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HK1136357A1 - Curable resin composition for sealing liquid crystal, and method for production of liquid crystal display panel using the same - Google Patents

Curable resin composition for sealing liquid crystal, and method for production of liquid crystal display panel using the same Download PDF

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Publication number
HK1136357A1
HK1136357A1 HK10103219.7A HK10103219A HK1136357A1 HK 1136357 A1 HK1136357 A1 HK 1136357A1 HK 10103219 A HK10103219 A HK 10103219A HK 1136357 A1 HK1136357 A1 HK 1136357A1
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Hong Kong
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liquid crystal
group
resin
resin composition
curable resin
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HK10103219.7A
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Chinese (zh)
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HK1136357B (en
Inventor
水田康司
中村健一
五味俊一
大塚裕明
宫胁孝久
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三井化学株式会社
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Publication of HK1136357A1 publication Critical patent/HK1136357A1/en
Publication of HK1136357B publication Critical patent/HK1136357B/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C09J133/062—Copolymers with monomers not covered by C09J133/06
    • C09J133/068—Copolymers with monomers not covered by C09J133/06 containing glycidyl groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
    • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
    • C08G59/20—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the epoxy compounds used
    • C08G59/32—Epoxy compounds containing three or more epoxy groups
    • C08G59/3209—Epoxy compounds containing three or more epoxy groups obtained by polymerisation of unsaturated mono-epoxy compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
    • C08L33/062—Copolymers with monomers not covered by C08L33/06
    • C08L33/068—Copolymers with monomers not covered by C08L33/06 containing glycidyl groups
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J163/00—Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2190/00—Compositions for sealing or packing joints
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
    • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
    • C08L2666/04—Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
    • C08L33/062—Copolymers with monomers not covered by C08L33/06
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
    • C08L33/08—Homopolymers or copolymers of acrylic acid esters
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1341—Filling or closing of cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2202/00—Materials and properties
    • G02F2202/02—Materials and properties organic material
    • G02F2202/022—Materials and properties organic material polymeric
    • G02F2202/023—Materials and properties organic material polymeric curable
    • G02F2202/025—Materials and properties organic material polymeric curable thermocurable

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Sealing Material Composition (AREA)
  • Liquid Crystal (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Polymerisation Methods In General (AREA)
  • Epoxy Resins (AREA)

Abstract

Disclosed is a curable resin composition for sealing a liquid crystal, which can be used as a sealing agent for a liquid crystal. The curable resin composition comprises an acrylic resin and/or a (meth)acrylic modified epoxy resin having at least one epoxy group and at least one (meth)acrylate group per molecule, a thermal radical polymerization initiator and a filler. The viscosity of the curable resin composition is 50 to 500 Pa s as measured at 25°C and 1.0 rpm on an E-type viscometer, and is greater than 500 Pa s as measured at 80°C and 1.0 rpm on an E-type viscometer. The curable resin composition has a high curing rate, and therefore can prevent the leakage of a liquid crystal and the contamination in a liquid crystal. A liquid crystal sealing agent comprising the curable resin composition can be used for producing a high-quality liquid crystal display panel at a high productivity rate.

Description

Curable resin composition for sealing liquid crystal and method for producing liquid crystal display panel using same
Technical Field
The present invention relates to a curable resin composition for sealing liquid crystal and a method for manufacturing a liquid crystal display panel using the same.
Background
In recent years, liquid crystal display panels have been widely used as display panels for various electronic devices including mobile phones, because of their characteristics such as thinness, lightness, and high definition. The liquid crystal display panel is a device which has a structure in which the outer periphery of liquid crystal sandwiched between 2 substrates is sealed with a liquid crystal sealant, controls the alignment of the liquid crystal by applying a voltage to the liquid crystal, and displays an image by adjusting the modulation of transmitted light.
The liquid crystal display panel is manufactured by, for example, a liquid crystal injection method as described below. In the liquid crystal injection method, a liquid crystal sealing agent is first applied to any one of 2 substrates to form a frame, and then the frame-shaped liquid crystal sealing agent is dried by a pre-curing treatment. Here, a notch to be a liquid crystal injection port is provided in advance in a part of the frame. Subsequently, after the 2 substrates were opposed and stacked, the substrates were bonded to each other by heating and pressing them. Thus, a cell for sealing liquid crystal was formed between 2 substrates. Subsequently, after liquid crystal is injected into the empty cell from the liquid crystal injection port in vacuum, the liquid crystal injection port is sealed with a liquid crystal sealant or the like, thereby manufacturing a liquid crystal display panel.
As a liquid crystal sealing agent for a liquid crystal injection method, for example, a thermosetting liquid crystal sealing agent (hereinafter, simply referred to as a thermosetting sealing agent) containing an epoxy resin as a main component has been proposed (for example, see patent document 1).
However, in recent years, the demand for liquid crystal display panels has increased dramatically with the miniaturization, thinness, high image quality, and the like of electronic devices. Therefore, in the field of manufacturing liquid crystal display panels, improvement in productivity including reduction in manufacturing time and the like, and improvement in quality of products are strongly desired. However, the above-mentioned liquid crystal injection method has a problem of low productivity because of a long injection time of the liquid crystal and the need of heat treatment at a temperature of 120 to 150 ℃ for several hours for curing the thermosetting sealing agent.
In view of this, recently, a liquid crystal dropping method has been attracting attention as a method for manufacturing a liquid crystal display panel capable of improving productivity. The liquid crystal dropping method generally comprises the following steps. First, a liquid crystal sealant is applied to any of 2 substrates constituting a liquid crystal display panel by a dispenser, screen printing, or the like to form a frame filled with liquid crystal. Next, after dropping an appropriate amount of liquid crystal into the frame, 2 substrates were stacked with a liquid crystal sealant in an uncured state in a high vacuum. Subsequently, the stacked 2 substrates are returned to atmospheric pressure or the like to bond the substrates to each other, and then the liquid crystal sealant is cured to manufacture a liquid crystal display panel in which liquid crystal is sealed between the 2 substrates. In the present invention, a frame made of a liquid crystal sealing agent is referred to as a sealing portion or a seal pattern.
In addition, in the liquid crystal dropping method, for the purpose of shortening the curing time of the liquid crystal sealing agent, the following method is adopted: a photo-and thermosetting liquid crystal sealing agent is used, and the liquid crystal sealing agent is once cured by irradiating ultraviolet rays or the like to the liquid crystal sealing agent and then post-cured by heating (for example, see patent documents 2 and 3). According to this liquid crystal dropping method, liquid crystal can be sealed between substrates in a shorter time than in the conventional liquid crystal injection method, and the curing time of the liquid crystal sealing agent is shortened, so that productivity is improved, and this method has recently become a mainstream method for manufacturing a liquid crystal display panel.
However, with the increasing complication of wiring mounted on a small panel such as a mobile phone, a seal pattern and the wiring are overlapped with each other, and a light shielding portion which does not directly contact light is likely to be generated on the seal pattern. However, in the light shielding portion, the liquid crystal sealant is insufficiently cured, and thus, in the post-curing by heating, leakage of the liquid crystal, in which the liquid crystal penetrates into the seal pattern to deform the seal pattern or the liquid crystal penetrates the seal pattern to leak, often occurs. If the liquid crystal leaks, the display characteristics of the liquid crystal display panel are significantly degraded, which is a serious problem.
Further, if the liquid crystal comes into contact with the liquid crystal sealant in an uncured state, the uncured liquid crystal sealant is eluted into the liquid crystal, and the liquid crystal is easily contaminated, and the contamination of the liquid crystal significantly degrades the display characteristics of the liquid crystal display panel. Accordingly, it is desired to provide a liquid crystal sealing agent which can suppress leakage of liquid crystal and contamination of liquid crystal.
Heretofore, as a liquid crystal sealing agent capable of improving leakage of liquid crystal, for example, a curable resin composition for a liquid crystal display element has been proposed, which has a viscosity of 200 to 400Pa · s measured with an E-type viscometer under a measurement condition of 25 ℃ and 1.0rpm and a viscosity of 20 to 500Pa · s measured under a measurement condition of 80 ℃ and 1.0rpm (see, for example, patent documents 4 and 5). As a liquid crystal sealing agent that can be sufficiently cured even in a light-shielding portion, for example, a liquid crystal sealing agent including a photocurable resin, a photo radical polymerization initiator, and a radical chain transfer agent having a disulfide bond has been proposed (for example, see patent document 6).
Patent document 7 proposes a liquid crystal sealing agent capable of suppressing contamination of liquid crystal, in which the amount of hydrogen-binding functional groups in 1 molecule is 3.5 × 10-3The above thermosetting resin for liquid crystal sealing. The amount of the hydrogen-bonding functional group in 1 molecule in the document is defined by the number of the hydrogen-bonding functional groups per molecular weight, and the document describes that the value is 3.5X 10-3The above resin has low affinity for liquid crystal, and thus can reduce contamination of liquid crystal when prepared into a liquid crystal sealing agent.
Patent document 1: international publication No. 2004/039885 pamphlet
Patent document 2: japanese patent laid-open publication No. 2001-133794
Patent document 3: japanese laid-open patent publication No. 2002-
Patent document 4: japanese patent laid-open publication No. 2005-308811
Patent document 5: japanese patent laid-open publication No. 2006 and 023580
Patent document 6: japanese patent laid-open publication No. 2006-030481
Patent document 7: japanese patent laid-open publication No. 2005-308813
Disclosure of Invention
However, in recent years, as the amount of information increases, the higher definition of the liquid crystal display panel has further progressed, and the proportion of the light shielding portion on the liquid crystal display panel has increased. The conventional techniques disclosed in the above-mentioned documents cannot sufficiently suppress deformation of the seal portion and leakage of liquid crystal into the seal portion during heat curing. In addition, in the liquid crystal sealing agent using high activation energy of photo radicals as in patent document 6, it is difficult to cure the liquid crystal sealing agent without leaving uncured portions in the conventional high definition.
As an effective method for reducing the uncured state of the liquid crystal sealing agent in the light shielding portion, there can be conceived: 1) the seal pattern is designed in consideration of the irradiation of light, and 2) the ultraviolet irradiation at the time of curing the liquid crystal sealing agent is changed to a heating method or the like in the liquid crystal dropping method. However, the method 1) is not preferable because of restrictions on panel design. Further, the photocurable liquid crystal sealing agent conventionally has a cost in terms of equipment cost for ultraviolet irradiation and energy cost, and thus has a problem in terms of manufacturing cost. On the other hand, the method of 2) is that the thermal curing reaction is generally slower than the photo curing reaction, and the viscosity of the resin is easily lowered upon heating. Therefore, the liquid crystal sealing agent using the thermosetting resin has a problem that it is difficult to solve the problem of liquid crystal leakage.
In view of this, the present inventors have previously studied a liquid crystal sealing agent having excellent leakage resistance. As a result, it was found that 1) the viscosity of the liquid crystal sealing agent at the time of heat curing, and 2) the composition of the liquid crystal sealing agent according to the radical chain transfer agent, the curable resin contained in the liquid crystal sealing agent, and the like affect the curability and the leak resistance.
In addition, the present inventors have studied the leakage resistance of the liquid crystal sealing agent disclosed in patent document 7 in the preliminary study, and as a result, found that the leakage resistance is insufficient. In this study, the amount of the functional group containing hydrogen bonding described in the comparative example of the document was 2.1 × 10-3The amount of epoxy groups was 2.9X 10-3The leakage resistance of the resin liquid crystal sealant of (3) was also investigated, and it was confirmed that the leakage resistance of the sealant was insufficient.
In view of the above problems, an object of the present invention is to provide a curable resin composition for liquid crystal sealing which can suppress liquid crystal leakage and liquid crystal contamination, and a method for manufacturing a high-quality liquid crystal display panel using the curable resin composition for liquid crystal sealing with high productivity.
The present inventors have conducted extensive studies and, as a result, have focused on the composition of the resin composition and the viscosity of the resin composition at the time of heat curing, have completed the present invention. That is, the above problems can be solved by the curable resin composition for liquid crystal sealing of the present invention.
A curable resin composition for sealing liquid crystals, which comprises an acrylic resin and/or a (meth) acrylic-modified epoxy resin having 1 or more epoxy groups and 1 or more (meth) acryloyl groups in each molecule, a thermal radical polymerization initiator, and a filler,
the viscosity at 25 ℃ and 1.0rpm measured by an E-type viscometer is 50 to 500 pas, and the viscosity at 80 ℃ and 1.0rpm is more than 500 pas.
Above-mentioned [1]The curable resin composition for sealing liquid crystals has an average primary particle diameter of the filler of 1.5 [ mu ] m or less and a specific surface area of 1 to 500m2In terms of the amount of the acrylic resin and (meth) acrylic acidThe total amount of the epoxy resin is 1 to 50 parts by mass,
the thixotropic index defined by [ viscosity at 25 ℃ and 0.5rpm measured by an E-type viscometer ]/[ viscosity at 25 ℃ and 5.0rpm measured by an E-type viscometer ] is 1.1 to 5.0.
The curable resin composition for sealing a liquid crystal according to the above [1] or [2], wherein the thermal radical polymerization initiator has a 10-hour half-life temperature of 40 to 80 ℃ defined as a temperature at which the concentration of the thermal radical polymerization initiator becomes half when the thermal decomposition reaction is carried out at a certain temperature for 10 hours.
A curable resin composition for sealing liquid crystals, which comprises a radical-curable resin having a radically polymerizable carbon-carbon double bond in 1 molecule, a thermal radical polymerization initiator, a radical chain transfer agent, and a filler.
The curable resin composition for sealing a liquid crystal according to [4], wherein the radical chain transfer agent is a thiol.
The curable resin composition for sealing a liquid crystal according to [4] or [5], wherein the thiol as the radical chain transfer agent is a secondary thiol having a number average molecular weight of 400 to 2000.
The curable resin composition for liquid crystal sealing according to any one of [4] to [6], which has a viscosity of 50 to 500 pas at 25 ℃ and 1.0rpm and a viscosity of more than 500 pas at 80 ℃ and 1.0rpm, as measured by an E-type viscometer.
A curable resin composition for sealing liquid crystals, which comprises a resin composition containing a radically polymerizable carbon-carbon double bond, a hydrogen-bonding functional group and an epoxy group, a thermal radical polymerization initiator and a filler; the resin composition comprises a resin composition consisting of (1A) a resin having a hydrogen-bonding functional group in 1 molecule and 2 carbon-carbon double bonds capable of radical polymerization, wherein the amount of the hydrogen-bonding functional group is 1.5X 10-3～6.0×10-3A radical reactive resin in mol/g, wherein (1B) has a hydrogen-bonding functional group in 1 molecule and an epoxy groupA radical and a radically polymerizable carbon-carbon double bond, the amount of the hydrogen-bonding functional group being 1.0X 10-4～5.0×10-3A radical reactive resin in mol/g, and (1C) 2 or more resins selected from the group consisting of epoxy resins having an epoxy group in 1 molecule but no radically polymerizable carbon-carbon double bond, a softening point of 40 ℃ or higher as measured by a ring and ball method, and a weight average molecular weight of 500 to 5000; the amount of the hydrogen-binding functional group in the resin composition is 1.0X 10-4～6.0×10-3mol/g, the amount of epoxy groups in the resin composition is 1.0X 10-4～2.6×10-3mol/g。
The curable resin composition for sealing a liquid crystal according to [8], wherein the hydrogen-bonding functional group in the resin composition is a hydroxyl group.
The curable resin composition for sealing a liquid crystal according to [8] or [9], wherein the radical-reactive resin (1A) is a resin represented by the following general formula (a1) or general formula (a 2);
[ solution 1]
General formula (a 1):
r in the above general formula (a1)1、R2、R3、R4Each independently represents a hydrogen atom or a methyl group, RmEach independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group, a hydroxyalkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, n represents an integer of 1 to 4, 1 represents an integer of 1 to 4, A represents a group represented by-CH2-、-C(CH3)2-、-SO2-or-O-represents an organic group;
[ solution 2]
General formula (a 2):
r in the above general formula (a2)5、R6、R7、R8Each independently represents a hydrogen atom or a methyl group, RqEach independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group, a hydroxyalkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, r represents an integer of 1 to 4, and p represents an integer of 1 to 4.
The curable resin composition for liquid crystal sealing according to any one of [8] to [10], wherein the radical-reactive resin (1A) is a resin represented by the following general formula (a3) or general formula (a 4);
[ solution 3]
General formula (a 3):
r in the above general formula (a3)1、R2Each independently represents a hydrogen atom or a methyl group, RmEach independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group, a hydroxyalkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, n represents an integer of 1 to 4, A represents a group represented by-CH2-、-C(CH3)2-、-SO2-or-O-represents an organic group;
[ solution 4]
General formula (a 4):
r in the above general formula (a4)5、R6Each independently representA hydrogen atom or a methyl group.
The curable resin composition for liquid crystal sealing according to [8], which has a viscosity of 50 to 500 pas at 25 ℃ and 1.0rpm and a viscosity of more than 500 pas at 80 ℃ and 1.0rpm, as measured by an E-type viscometer.
The curable resin composition for liquid crystal sealing according to [8], further comprising a radical chain transfer agent.
The curable resin composition for liquid crystal sealing according to [13], which has a viscosity of 50 to 500 pas at 25 ℃ and 1.0rpm and a viscosity of more than 500 pas at 80 ℃ and 1.0rpm, as measured by an E-type viscometer.
The above problems can be solved by a method for manufacturing a liquid crystal display panel according to the present invention.
A method for manufacturing a liquid crystal display panel in which 2 substrates facing each other are bonded to each other with a curable resin composition for liquid crystal sealing, comprising: preparing a1 st substrate including a frame-shaped display region in which a pixel array region is surrounded by the curable resin composition for liquid crystal sealing described in [1], [4], or [8 ]; dropping a liquid crystal into the display region in an uncured state or into another substrate; a step of superposing the 1 st substrate and the 2 nd substrate opposed thereto; and curing the resin composition for sealing liquid crystal by heating.
The present invention can provide a curable resin composition for sealing liquid crystal, which can suppress leakage of liquid crystal and contamination of liquid crystal, and a method for manufacturing a high-quality liquid crystal display panel using the resin composition with high productivity.
Detailed Description
The present invention will be described in detail. In the following description, the numerical range is defined by "to", and the term "to" in the present invention includes the end values thereof. For example, "10 to 100" means 10 or more and 100 or less.
In the present invention, "liquid crystal sealing" means "sealing liquid crystal" and "sealing liquid crystal" means "sealing liquid crystal in a certain space". Accordingly, the term "curable resin composition for liquid crystal sealing" as used in the present invention generally refers to the same substances as those referred to as "liquid crystal sealing agents". The "liquid crystal sealant" seals liquid crystal between 2 substrates in the liquid crystal display panel, and functions as an adhesive for attaching the 2 substrates. In the present invention, a sealant used in a liquid crystal dropping method among liquid crystal sealants may be referred to as a "liquid crystal sealant for a liquid crystal dropping method". In the following description, the "curable resin composition for liquid crystal sealing" may be referred to as a "composition", a "liquid crystal sealing agent" or a "sealing agent".
1. Curable resin composition for sealing liquid crystal
The first curable resin composition for sealing liquid crystals is characterized by comprising (1) an acrylic resin and/or (2) a (meth) acrylic-modified epoxy resin having at least one epoxy group and at least one (meth) acryloyl group in 1 molecule, (3) a thermal radical polymerization initiator, and (4) a filler, and has a viscosity of 50 to 500 pas at 25 ℃ and 1.0rpm, and a viscosity of more than 500 pas at 80 ℃ and 1.0rpm, as measured by an E-type viscometer. In the present invention, acryloyl and methacryloyl are collectively referred to as (meth) acryloyl. The curable resin composition for liquid crystal sealing of the present invention having the above-described characteristics is also referred to as a "curable resin composition for liquid crystal sealing" or a "resin composition".
The viscosity was measured using an E-type rotational viscometer (for example, DII-III ULTRA, digital rheometer manufactured by Boehringer corporation) using a CP-52 cone-plate type sensor having a radius of 12mm and an angle of 3 degrees, with the number of revolutions set at 1.0 rpm. The viscosity at 25 ℃ is measured at a predetermined temperature, and the viscosity at 25 ℃ is measured by the above-mentioned method after leaving the curable resin composition for liquid crystal sealing I at 25 ℃ for 5 minutes. The viscosity at 80 ℃ means the viscosity measured by the above method after placing the above composition in a cup of an E-type rotational viscometer, raising the temperature to 80 ℃ at a rate of 5 ℃/minute, and then leaving it at 80 ℃ for 5 minutes.
When the viscosity at 1.0rpm measured by the E-type rotational viscometer is greater than 780 pas, the measurement is preferably carried out by the parallel plate method. This is because the E-type rotational viscometer uses a rotor No. 5, and about 780Pa · s is a measurement limit. The measurement by the parallel plate method can be performed by a standard method of the model using a viscoelastic type measuring instrument such as RheoStress RS150 (manufactured by HAAKE).
The curable resin composition I for liquid crystal sealing is characterized in that the viscosity at 25 ℃ and 1.0rpm is 50 to 500 pas, the viscosity at 80 ℃ and 1.0rpm is more than 500 pas, and the viscosity at 25 ℃ and 1.0rpm is more preferably 100 to 400 pas. Such a composition can easily remove bubbles contained in the liquid crystal sealing agent in the step of applying the composition as the liquid crystal sealing agent to the substrate, and can provide a high-quality liquid crystal display panel.
The curable resin composition I for liquid crystal sealing is characterized by having a viscosity of more than 500 pas at 80 ℃ and 1.0 rpm. Generally, the viscosity of a thermosetting resin is temporarily lowered when the resin is cured by heating, and then the viscosity is raised again as the curing reaction proceeds. The curing temperature of the liquid crystal sealing agent in the manufacture of the liquid crystal display panel is usually about 80 to 150 ℃. As described above, when the viscosity of the composition is too low in the curing step, problems such as leakage of liquid crystal occur.
Therefore, in order to prevent the leakage of the liquid crystal (to improve the leakage resistance), it is effective to suppress the decrease in the viscosity of the composition during heat curing. In order to suppress the decrease in viscosity of the composition during heat curing, it is effective to increase the viscosity of the composition by carrying out a curing reaction of the composition before the decrease in viscosity occurs. In addition, to suppress the leakage of liquid crystal, the temperature was 80 ℃ and the temperature was 1.0rThe viscosity of the composition in pm is 500 pas, a reference value. Therefore, the resin composition I of the present invention is designed in composition by using a thermal radical polymerization initiator or the like having a 10-hour half-life temperature in a predetermined range as described later, so as to accelerate curing of the composition. Thus, the viscosity of the composition at 80 ℃ and 1.0rpm is more than 500 pas, and the viscosity of the composition can be increased before the viscosity is reduced, so that the viscosity reduction during heat curing can be suppressed. Here, the viscosity at 80 ℃ is preferably 10 from the viewpoint of further suppressing the decrease in viscosity of the composition3～109Pa · s, more preferably 103～107Pa·s。
Further, the thixotropic index defined by [ viscosity at 25 ℃ and 0.5rpm ]/[ viscosity at 25 ℃ and 5.0rpm ] of the curable resin composition I for liquid crystal sealing is 1.1 to 5.0, preferably 1.2 to 2.5. Thixotropic index refers to the ratio of viscosity measured at a relatively low shear rate to viscosity measured at a relatively high shear rate. At high values, the fluid exhibits high viscosity at low shear rates, but low viscosity at high shear rates.
In the production of a liquid crystal display panel, the liquid crystal sealant is in a state of relatively high shear rate in the step of applying the liquid crystal sealant to the substrate, and then in a state of extremely low shear rate in the step of laminating the substrates and post-curing. Here, in the step of applying the liquid crystal sealing agent to the substrate (high shear rate region), it is necessary to facilitate the application and the defoaming of the liquid crystal sealing agent, and therefore the liquid crystal sealing agent is preferably low in viscosity. In addition, in the curing process (low shear region), the liquid crystal sealant is preferably high in viscosity so as not to cause leakage of the liquid crystal as described above. From such a viewpoint, the thixotropic index of the curable resin composition I for liquid crystal sealing is set in the above range in order to improve coatability, defoaming property, and reliability when used as a liquid crystal sealing agent.
The composition I is characterized by having (1) an acrylic resin and/or (2) a (meth) acrylic-modified epoxy resin having at least one epoxy group and one (meth) acryloyl group in 1 molecule, respectively, as a base resin, and containing therein (3) a thermal radical polymerization initiator and (4) a filler, and is a so-called one-pack curable resin composition in which a main agent (curable resin) in an uncured state and a curing agent (curing accelerator) are mixed. The one-pack curable resin composition is excellent in workability because it does not require mixing of a main agent and a curing agent at the time of use.
Next, the respective components of the curable resin composition I for liquid crystal sealing of the present invention will be described.
(1) Acrylic resin
The acrylic resin of the present invention means an acrylate and/or methacrylate monomer, or an oligomer thereof. These examples include the following.
Diacrylate and/or dimethacrylate of polyethylene glycol, propylene glycol, polypropylene glycol, etc., diacrylate and/or dimethacrylate of tris (2-hydroxyethyl) isocyanurate, diacrylate and/or dimethacrylate of diol obtained by adding 4mol or more of ethylene oxide or propylene oxide to 1mol of neopentyl glycol, diacrylate and/or dimethacrylate of diol obtained by adding 2mol or more of ethylene oxide or propylene oxide to 1mol of bisphenol A, di-or triacrylate and/or di-or trimethacrylate of triol obtained by adding 3mol or more of ethylene oxide or propylene oxide to 1mol of trimethylolpropane, diacrylate and/or dimethacrylate of diol obtained by adding 4mol or more of ethylene oxide or propylene oxide to 1mol of bisphenol A, tris (2-hydroxyethyl) isocyanurate triacrylate and/or trimethacrylate, trimethylolpropane triacrylate and/or trimethacrylate, or an oligomer thereof, pentaerythritol triacrylate and/or trimethacrylate, or an oligomer thereof, polyacrylate and/or polymethacrylate of dipentaerythritol, tris (acryloyloxyethyl) isocyanurate, caprolactone-modified tris (methacryloyloxyethyl) isocyanurate, polyacrylate and/or polymethacrylate of alkyl-modified dipentaerythritol, polyacrylate and/or polymethacrylate of caprolactone-modified dipentaerythritol, hydroxypivalic acid neopentyl glycol diacrylate and/or dimethacrylate, caprolactone-modified hydroxypivalic acid neopentyl glycol diacrylate and/or dimethacrylate, ethylene oxide-modified phosphoric acid acrylate and/or dimethacrylate, ethylene oxide-modified alkylated phosphoric acid acrylate and/or methacrylate, oligomeric acrylates and/or oligomeric methacrylates of neopentyl glycol, trimethylolpropane, pentaerythritol and the like.
Specific examples of the acrylic resin include resins obtained by reacting all epoxy groups of cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol a type epoxy resin, bisphenol F type epoxy resin, triphenol methane type epoxy resin, triphenol ethane type epoxy resin, triphenol type epoxy resin, diphenyl ether type epoxy resin, dicyclopentadiene type epoxy resin, biphenyl type epoxy resin, and the like with (meth) acrylic acid, and the epoxy resins are completely (meth) acrylated. Further, the acrylic resin of the present invention is preferably highly purified by a water washing method or the like.
The acrylic resin of the invention preferably has a number average molecular weight of 300-2000 and a Fedors theoretical solubility parameter (sp value) of 10.0-13.0 (cal/cm)3)1/2The range of (1). Such an acrylic resin is preferable because it has low solubility and diffusibility in liquid crystal, and a liquid crystal sealing agent containing the resin can provide a liquid crystal display panel having good display characteristics. Further, since the compatibility with the epoxy resin (6) described later is also good, a homogeneous liquid crystal sealing agent can be provided. The number average molecular weight can be measured, for example, by Gel Permeation Chromatography (GPC) using polystyrene as a standard.
There are various means and methods for calculating the solubility parameter (sp value), and the theoretical solubility parameter in the present invention is preferably a parameter based on a calculation method created by Fedors (see Japanese society for subsequent study , vol.22, No.10(1986) ((53), (566)), etc.). This is because the calculation does not require density values and the solubility parameter can be easily calculated. The theoretical solubility parameter of the above-mentioned Fedors is calculated by the following formula.
[ number 1]
sp value (∑ Δ el/∑ Δ vl)1/2
Where Σ Δ el ═ Δ H-RT and Σ Δ vl ═ the sum of the molar capacities
When the solubility parameter is within the above range, the acrylic resin is preferably low in solubility in liquid crystal, and contamination of liquid crystal is suppressed, so that display characteristics of the liquid crystal display panel are improved.
The acrylic resin may be a mixture of a plurality of the above resins in combination. In this case, the theoretical solubility parameter of the entire mixed composition can be calculated based on the sum of the mole fractions of the acrylate monomers and/or methacrylate monomers, or oligomers thereof to be mixed. The value is preferably 10.0 to 13.0 (cal/cm)3)1/2。
The number average molecular weight is 300-2000, and the theoretical solubility parameter of Fedors is 10.0-13.0 (cal/cm)3)1/2Examples of the acrylic resin within the above range include pentaerythritol tetraacrylate (number average molecular weight: 352, sp value 12.1).
(2) (meth) acrylic-modified epoxy resin having 1 or more epoxy groups and 1 or more (meth) acryloyl groups in each molecule
The "(meth) acrylic-modified epoxy resin having 1 or more epoxy groups and (meth) acryloyl groups in 1 molecule (may be simply referred to as" modified epoxy resin ") in the present invention" refers to a compound having both a (meth) acryloyl group and an epoxy group in 1 molecule.
Examples of the modified epoxy resin include resins obtained by reacting an epoxy resin such as a bisphenol type epoxy resin or a novolak type epoxy resin with (meth) acrylic acid or phenyl methacrylate in the presence of an alkali catalyst.
Examples of the epoxy resin as a raw material of the above-mentioned modified epoxy resin include cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol a type epoxy resin, bisphenol F type epoxy resin, triphenol methane type epoxy resin, triphenol ethane type epoxy resin, triphenol type epoxy resin, dicyclopentadiene type epoxy resin, biphenyl type epoxy resin and the like.
Among them, a bifunctional epoxy resin having 2 epoxy groups in the molecule, such as a bisphenol a type epoxy resin and a bisphenol F type epoxy resin, is preferably reacted with acrylic acid at a molar ratio of epoxy group to acrylic acid of approximately 1: 1. The epoxy resin is preferably purified by a molecular distillation method, a washing method, or the like.
The modified epoxy resin has both an epoxy group and a (meth) acryloyl group in the resin skeleton, and therefore has excellent compatibility with (1) an acrylic resin and (6) an epoxy resin described later in the curable resin composition for liquid crystal sealing. Thus, a cured product of the composition having a high glass transition temperature (Tg) and excellent adhesiveness can be provided. The excellent adhesiveness of the cured product of the composition means that the cured product has high adhesive strength with the substrate, and a high-quality liquid crystal display panel can be provided.
In the present invention, (1) the acrylic resin and (2) the modified epoxy resin may be used in an arbitrary ratio. The examples include a) a mode in which the modified epoxy resin of (2) is not used and only the acrylic resin of (1) is used, and b) a mode in which the acrylic resin of (1) is not used and only the modified epoxy resin of (2) is used. In this case, the case of a), a curable resin composition for liquid crystal sealing having good leakage resistance can be provided. b) In the case of (2), the modified epoxy resin and the epoxy curing agent (5) described later are appropriately combined to provide a curable resin composition for sealing liquid crystals, which has high adhesive strength. In the present invention, among the properties of the liquid crystal sealing agent, the property that the liquid crystal sealing agent has a high adhesive strength to a member to be bonded such as a substrate is referred to as excellent adhesion reliability.
In addition, (1) an acrylic resin and (2) a modified epoxy resin may be used in combination. The mixing ratio of the acrylic resin (1) and the modified epoxy resin (2) is preferably 10-70: 90-30, more preferably 20-50: 80-50, in terms of weight ratio. Thus, a curable resin composition for sealing liquid crystals having excellent adhesion reliability can be provided. In the present invention, a resin composition containing (1) an acrylic resin and (2) a modified epoxy resin is sometimes referred to as a "resin unit".
(3) Thermal radical polymerization initiator
The thermal radical polymerization initiator is a compound which generates radicals when heated, that is, a compound which generates radical species by being decomposed after absorbing heat energy. Such a thermal radical polymerization initiator is suitable for curing a liquid crystal sealing agent by heating after a substrate is attached.
The thermal radical polymerization initiator preferably has a 10-hour half-life temperature within a range of 30 to 80 ℃, more preferably 40 to 80 ℃, and particularly preferably 50 to 70 ℃. The 10-hour half-life temperature is a temperature at which the concentration of the thermal radical polymerization initiator becomes half of the original concentration when the thermal radical polymerization initiator is subjected to a thermal decomposition reaction for 10 hours at a certain temperature under an inert gas. The liquid crystal sealant using the thermal radical polymerization initiator having the 10-hour half-life temperature within the above range has a good balance between viscosity stability and curability.
As described above, from the viewpoint of suppressing leakage of liquid crystal due to excessive viscosity reduction during heat curing, the above-described viscosity reduction is preferably suppressed in the curable resin composition for liquid crystal sealing, and this can be achieved by accelerating the curing reaction of the composition and accelerating gelation. From the viewpoint of accelerating gelation, the 10-hour half-life temperature of the thermal radical polymerization initiator is preferably 80 ℃ or less, and more preferably 70 ℃ or less. Thus, radicals are easily generated when the composition is heat-cured (usually, the curing temperature is 80 to 150 ℃), the curing reaction is accelerated, and the viscosity reduction during heat curing is suppressed.
On the other hand, if the 10-hour half-life temperature of the thermal radical polymerization initiator is too low, the curing reaction is easily progressed even at room temperature, so that the stability of the liquid crystal sealing agent is deteriorated. From this viewpoint, if the 10-hour half-life temperature of the thermal radical polymerization initiator is 30 ℃, preferably 40 ℃ or higher, the stability of the liquid crystal sealing agent during storage and in the coating step (usually performed at room temperature) on the substrate is good.
Here, the thermal radical polymerization initiator having a 10-hour half-life temperature of more than 80 ℃ hardly generates radicals. Therefore, the liquid crystal sealing agent containing the thermal radical polymerization initiator is not preferable because it has low curability. On the other hand, in the case where the 10-hour half-life temperature of the thermal radical polymerization initiator is less than 30 ℃, since the curing reaction is easily performed even at room temperature, the viscosity stability of the liquid crystal sealing agent containing the thermal radical polymerization initiator is remarkably lowered. As described above, the 10-hour half-life temperature of the thermal radical polymerization initiator is preferably within the above range.
The 10-hour half-life temperature is specifically determined as follows. First, when the thermal decomposition reaction is expressed as a primary reaction formula, the following relation is established.
[ number 2]
ln(C0/Ct)＝kd×t
C0: initial concentration of thermal radical generator
Ct: concentration of thermal radical generator after time t
kd: rate constant of thermal decomposition
t: reaction time
The half-life is C when the concentration of the thermal radical polymerization initiator becomes halft＝C0The case of/2. Thus, it is established when the thermal radical polymerization initiator has reached a half-life after t hoursThe following formula.
[ number 3]
kd＝(1/t)×ln2
On the other hand, the temperature dependence of the velocity constant is expressed by the arrhenius equation, and the following equation is established.
[ number 4]
kd＝Aexp(-ΔE/RT)
The following formula can be derived from the above formula.
[ number 5]
(1/t)×ln2＝Aexp(-ΔE/RT)
A: frequency factor
Δ E: activation energy
R: gas constant (8.314J/mol. K)
T: absolute temperature (K)
The values of A and Δ E are described in Polymer Handboot four edition, J.Brandrup et al, volume 1, II-2 to II-69, WILEY-INTERSCIENCE, (1999). As described above, if T is set to 10 hours, the 10-hour half-life temperature T can be obtained.
As the thermal radical polymerization initiator, a known compound can be used. Representative examples thereof include organic peroxides and azo compounds.
The organic peroxide is preferably an organic peroxide classified into ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, peroxydicarbonate, and is not particularly limited, and a known organic peroxide can be used.
Specific examples of the organic peroxide are shown below. The number in parentheses indicates the 10-hour half-life temperature (see Wako pure chemical industries, catalogues of API Co., Ltd., and the above-mentioned Polymer handbook).
Examples of the ketone peroxides include methyl ethyl ketone peroxide (109 ℃ C.), cyclohexanone peroxide (100 ℃ C.), etc. In addition, examples of the peroxyketals include 1, 1-bis (t-hexylperoxy) 3, 3, 5-trimethylcyclohexane (87 ℃ C.), 1-bis (t-hexylperoxy) cyclohexane (87 ℃ C.), 1-bis (t-butylperoxy) cyclohexane (91 ℃ C.), 2-bis (t-butylperoxy) butane (103 ℃ C.), 1- (t-amylperoxy) cyclohexane (93 ℃ C.), n-butyl-4, 4-bis (t-butylperoxy) valerate (105 ℃ C.), 2-bis (4, 4-di-t-butylperoxycyclohexyl) propane (95 ℃ C.).
Examples of hydroperoxides include p-menthane hydroperoxide (128 deg.C), diisopropylbenzene peroxide (145 deg.C), 1, 3, 3-tetramethylbutyl hydroperoxide (153 deg.C), cumene hydroperoxide (156 deg.C), tert-butyl hydroperoxide (167 deg.C), and the like.
Examples of the dialkyl peroxides include α, α -di (t-butylperoxy) diisopropylbenzene (119 ℃), dicumyl peroxide (116 ℃), 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane (118 ℃), t-butylcumyl peroxide (120 ℃), t-amyl peroxide (123 ℃), di-t-butyl peroxide (124 ℃), 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexene-3 (129 ℃).
Examples of the peroxyesters include cumylperoxidate neodecanoate (37 ℃ C.), 1, 3, 3-tetramethylbutylperoxyneodecanoate (41 ℃ C.), t-hexylperoxyneodecanoate (45 ℃ C.), t-butylperoxyneodecanoate (46 ℃ C.), t-amylperoxyneodecanoate (46 ℃ C.), t-hexylperoxypivalate (53 ℃ C.), t-butylperoxypivalate (55 ℃ C.), t-amylperoxypivalate (55 ℃ C.), 1, 3, 3-tetramethylbutylperoxy-2-ethylhexanoate (65 ℃ C.), 2, 5-dimethyl-2, 5-di (2-ethylhexanoylperoxy) hexane (66 ℃ C.), t-hexylperoxy-2-ethylhexanoate (70 ℃ C.), t-butylperoxy-2-ethylhexanoate (72 ℃ C.), and mixtures thereof, T-amyl peroxy-2-ethylhexanoate (75 ℃), t-butyl peroxy isobutyrate (82 ℃), t-hexyl peroxy isopropyl monocarbonate (95 ℃), t-butyl peroxy maleate (96 ℃), t-amyl peroxy n-octanoate (96 ℃), t-amyl peroxy isononanoate (96 ℃), t-butyl peroxy-3, 5, 5-trimethyl hexanoate (97 ℃), t-butyl peroxy laurate (98 ℃), t-butyl peroxy isopropyl monocarbonate (99 ℃), t-butyl peroxy-2-ethylhexyl monocarbonate (99 ℃), t-hexyl peroxy benzoate (99 ℃), 2, 5-dimethyl-2, 5-di (benzoyl peroxy) hexane (100 ℃), t-amyl peroxy acetate (100 ℃), t-amyl peroxy benzoate (100 ℃), sodium tert-butyl peroxy isopropyl peroxybenzoate (95 ℃), sodium tert-butyl peroxy-3, 5, 5-trimethyl hexanoate (97 ℃), sodium tert-butyl peroxy-propyl peroxybenzoate (99 ℃), sodium tert, T-butyl peroxyacetate (102 ℃ C.), t-butyl peroxybenzoate (104 ℃ C.).
Examples of diacyl peroxides include diisobutyl peroxide (33 ℃ C.), bis-3, 5, 5-trimethylhexanoyl peroxide (60 ℃ C.), dilauroyl peroxide (62 ℃ C.), disuccinic acid peroxide (66 ℃ C.), dibenzoyl peroxide (73 ℃ C.).
Examples of peroxydicarbonates include di-n-propyl peroxydicarbonate (40 ℃ C.), diisopropyl peroxydicarbonate (41 ℃ C.), bis (4-t-butylcyclohexyl) peroxydicarbonate (41 ℃ C.), bis-2-ethylhexyl peroxydicarbonate (44 ℃ C.), t-amyl peroxypropyl dicarbonate (96 ℃ C.), t-amyl peroxy2-ethylhexyl dicarbonate (99 ℃ C.).
Next, an azo compound which functions as a thermal radical polymerization initiator (may be referred to as an "azo thermal radical polymerization initiator") will be described. Examples of the azo-based thermal radical polymerization initiator include water-soluble azo-based thermal radical polymerization initiators, oil-soluble azo-based thermal radical polymerization initiators, and macromolecular azo-based thermal radical polymerization initiators.
Examples of the water-soluble azo-based thermal radical polymerization initiator include 2, 2 ' -azobis [2- (2-imidazolin-2-yl) propane ] disulfate dihydrate (46 ℃ C.), 2 ' -azobis [ N- (2-carboxyethyl) -2-methylpropionamidine ] hydrate (57 ℃ C.), 2 ' -azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl ] propane } hydrogen dichloride (60 ℃ C.), 2 ' -azobis (1-imino-1-pyrrolidinyl-2-ethylpropane) hydrogen chloride (67 ℃ C.), 2 ' -azobis [ 2-methyl-N- (2-hydroxyethyl) propionamide (87 ℃ C.), 2, 2 '-azobis [2- (2-imidazolin-2-yl) propane ] dichloride (44 ℃), 2' -azobis (2-methylpropionamidine) dichloride (56 ℃), 2 '-azobis [2- (2-imidazolin-2-yl) propane ] (61 ℃), 2' -azobis { 2-methyl-N- [1, 1-bis (hydroxymethyl) -2-hydroxyethyl ] propionamide } (80 ℃).
Examples of the oil-soluble azo-based thermal radical polymerization initiator include 2, 2 '-azobis (4-methoxy-2, 4-dimethylvaleronitrile) (30 ℃ C.), dimethyl-2, 2' -azobis (2-methylpropionate) (66 ℃ C.), 1 '-azobis (cyclohexane-1-carbonitrile) (88 ℃ C.), 1' - [ (cyano-1-methylethyl) azo ] formamide (104 ℃ C.), 2 '-azobis (N-cyclohexyl-2-methylpropionamide) (111 ℃ C.), 2' -azobis (2, 4-dimethylpentanenitrile) (51 ℃ C.), 2 '-azobis (2-methylbutyronitrile) (67 ℃ C.), 2' -azobis [ N- (2-propenyl) -2-methylpropionamide ] (96 ℃ C.), 2, 2' -azobis (N-butyl-2-methylpropionamide) (110 ℃ C.).
Examples of the polymer azo-based thermal radical polymerization initiator include a polymer azo-based thermal radical polymerization initiator containing a polydimethylsiloxane unit, a polymer azo-based thermal radical polymerization initiator containing a polyethylene glycol unit, and the like. Further, a mixture of these compounds in any combination can also be used as a thermal radical polymerization initiator.
The thermal radical polymerization initiator is preferably 0.01 to 3.0 parts by mass per 100 parts by mass of the resin unit containing the above (1) and (2). When the amount of the thermal radical polymerization initiator is too large, the viscosity stability becomes poor; when too small, curability becomes poor.
(4) Filler material
The filler of the present invention is a filler added for the purpose of controlling the viscosity of a liquid crystal sealing agent, improving the strength of a cured product, controlling linear expansion, and the like. By filling the filler, the adhesion reliability of the liquid crystal sealing agent can be improved. The filler is not limited as long as it is a filler generally used in the field of electronic materials.
Examples of the filler include inorganic fillers such as calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, zirconium silicate, iron oxide, titanium oxide, aluminum oxide (alumina), zinc oxide, silica, potassium titanate, kaolin, talc, glass beads, sericite activated clay, bentonite, aluminum nitride, and silicon nitride.
In addition, organic fillers may also be used in the present invention. The organic filler is usually an organic compound having a softening point temperature of more than 120 ℃ as measured by the ring and ball method (JACT test method: RS-2). The rubber particles having a softening point of room temperature or lower in the present invention are also effective as an organic filler. Examples of the organic filler include polymethyl methacrylate, polystyrene, and a copolymer obtained by copolymerizing monomers copolymerizable therewith, polyester particles, polyurethane particles, and rubber particles.
Among these, inorganic fillers are preferable as fillers in terms of reducing the linear expansion coefficient of the liquid crystal sealing agent and maintaining the shape thereof well. Among them, silica and talc are particularly preferable because ultraviolet rays are hardly transmitted.
The shape of the filler is not particularly limited, regardless of the difference between inorganic and organic. That is, any filler having a definite shape or an indefinite shape such as a spherical shape, a plate shape, or a needle shape can be used. The filler preferably has an average primary particle diameter of 1.5 μm or less and a specific surface area of 1 to 500m2(ii) in terms of/g. The curable resin composition for sealing liquid crystals, which contains such a filler, has a good balance between thixotropy and viscosity. The average primary particle diameter of the filler can be measured by a laser diffraction method described in JIS Z8825-1, and the specific surface area can be measured by a BET method described in JIS Z8830.
In addition, from the viewpoint of suppressing the leakage of the liquid crystal, it is preferable to use 2 or more kinds of fillers in combination. The 2 or more fillers are 2 or more different in material, 2 or more different in average particle diameter with the same material, or a combination thereof. When the average particle diameters are different, the average particle diameters of the fillers are preferably different by 0.3 μm or more.
The amount of the filler to be filled is preferably 1 to 50 parts by mass, more preferably 10 to 30 parts by mass, per 100 parts by mass of the resin unit containing the above (1) and (2). When the amount of the filler is within the above range, the thixotropic index of the curable resin composition for liquid crystal sealing can be easily controlled to 1.1 to 5.0, which is preferable. The thixotropic index is a value obtained by [ viscosity at 25 ℃ C. and 0.5rpm measured by an E-type viscometer ]/[ viscosity at 25 ℃ C. and 5.0rpm measured by an E-type viscometer ].
(5) Epoxy curing agent
The curable resin composition I for liquid crystal sealing may further contain an epoxy curing agent. Among them, a latent epoxy curing agent is preferable as the epoxy curing agent. The latent epoxy curing agent is a curing agent which does not cure an epoxy resin even when mixed in an epoxy resin in a state where the resin is normally stored (room temperature, under visible light, etc.), but cures the epoxy resin by heat or light. By using the latent epoxy curing agent, the thermosetting property of the curable resin composition for liquid crystal sealing I is improved.
As the latent epoxy curing agent, known ones can be used. Among these, from the viewpoint of excellent viscosity stability, a latent epoxy curing agent having a melting point or a softening point temperature measured by the ring and ball method of 100 ℃ or higher is preferable. The composition containing the latent epoxy curing agent is effective as a one-pack type. Examples of the latent epoxy curing agent include organic acid dihydrazide compounds, imidazole and its derivatives, dicyandiamide, aromatic amines, and the like. These curing agents may also be used as a mixture in an appropriate combination.
In screen printing and dispensing devices used for coating of a composition, since the residence time of the composition in the device is long, it is difficult to use a composition having poor storage stability. In this respect, particularly, a composition containing an amine-based latent curing agent having a melting point or a softening point temperature measured by a ring and ball method of 100 ℃ or higher is effective because it has extremely good viscosity stability at room temperature and can be used for a long time in screen printing and a dispenser.
Examples of the amine-based latent curing agent include dicyandiamide (melting point 209 ℃ C.), dicyandiamide (melting point 181 ℃ C.), organic acid dihydrazides such as adipic acid dihydrazide (melting point 181 ℃ C.), 1, 3-bis (hydrazinocarbonylethyl) -5-isopropylhydantoin (melting point 120 ℃ C.), dodecanedioic acid dihydrazide (melting point 190 ℃ C.), sebacic acid dihydrazide (melting point 189 ℃ C.), 2, 4-diamino-6- [2 '-ethylimidazol-1' -yl ] -ethyltriazine (melting point 215 to 225 ℃ C.), 2-phenylimidazole (melting point 137 to 147 ℃ C.), and other imidazole derivatives.
From the viewpoint of obtaining a curable resin composition I for liquid crystal sealing excellent in viscosity stability and adhesion reliability, the content of the latent epoxy curing agent is preferably 3 to 30 parts by mass per 100 parts by mass of the resin unit. The latent epoxy curing agent is preferably highly purified by a water washing method, a recrystallization method, or the like.
(6) Epoxy resin
The curable resin composition I for liquid crystal sealing may further contain an epoxy resin. The epoxy resin of the present invention is a compound having 1 or more epoxy groups in the molecule (except for the modified epoxy resin (2) described above).
Examples of epoxy resins applicable in the present invention include: aromatic polyglycidyl ether compounds (hereinafter, for example, an epoxy resin obtained from bisphenol a is referred to as "bisphenol a-type epoxy resin") obtained by reacting epichlorohydrin with aromatic glycols represented by bisphenol a, bisphenol S, bisphenol F, bisphenol AD and the like, and glycols obtained by modifying these with ethylene glycol, propylene glycol, or alkylene glycol; a novolak-type polyglycidyl ether compound obtained by reacting a novolak resin derived from phenol or cresol and formaldehyde, a polyphenol represented by a polyallyphenol and a copolymer thereof, and the like, with epichlorohydrin; glycidyl ether compounds of xylyl phenol resins.
Among them, cresol novolac type epoxy resins, phenol novolac type epoxy resins, bisphenol a type epoxy resins, bisphenol F type epoxy resins, triphenol methane type epoxy resins, triphenol ethane type epoxy resins, trisphenol type epoxy resins, dicyclopentadiene type epoxy resins, diphenyl ether type epoxy resins, and biphenyl type epoxy resins are preferable as the epoxy resins. These resins may also be used in combination. The epoxy resin is preferably a resin which has been subjected to a high-purity treatment by a molecular distillation method or the like.
The epoxy resin preferably has a softening point of 40 ℃ or higher as measured by a ring and ball method and a weight average molecular weight of 500 to 10000. This is because when the softening point and the weight average molecular weight of the epoxy resin are within the above ranges, the solubility and the diffusivity of the epoxy resin to the liquid crystal are low, and the display characteristics of the obtained liquid crystal display panel are good. Further, since the curable resin composition for liquid crystal sealing has good compatibility with the acrylic resin (1), the adhesion reliability of the curable resin composition for liquid crystal sealing to the member to be adhered is improved. From such a viewpoint, the weight average molecular weight of the epoxy resin is particularly preferably in the range of 1000 to 2000. The weight average molecular weight of the epoxy resin can be measured, for example, by GPC with polystyrene as a standard.
(7) Photo-radical polymerization initiator
The curable resin composition for liquid crystal sealing I may further contain a photo radical polymerization initiator. The photo radical polymerization initiator refers to a compound that generates radicals by light. The curable resin composition I for liquid crystal sealing containing a photo radical polymerization initiator can be temporarily cured by photocuring, and therefore, the workability becomes easy. Needless to say, the curable resin composition I for liquid crystal sealing may not contain a photo radical polymerization initiator. The curable resin composition for sealing liquid crystal, which does not contain a photo radical polymerization initiator, is cured only by heating, and therefore, there is an advantage that a photo curing step which imposes a large burden on cost can be omitted.
The photo radical polymerization initiator is not particularly limited, and a known compound can be used. Examples of the compound include benzoin compounds, acetophenones, benzophenones, thioxanthones, α -acyloxime esters, phenylglyoxylic acids, benzil compounds, azo compounds, diphenyl sulfide compounds, acylphosphine oxide compounds, organic dye compounds, iron-phthalocyanine compounds, benzoin ethers, and anthraquinones.
The content of the photo radical polymerization initiator is preferably 0.1 to 5.0 parts by mass, more preferably 0.3 to 5.0 parts by mass, per 100 parts by mass of the resin unit. The composition containing the photo-radical polymerization initiator in an amount of 0.3 parts by mass or more has good curability by light irradiation. On the other hand, the composition having a content of 5.0 parts by mass or less is excellent in stability when applied to a substrate.
When the resin composition containing the photo radical polymerization initiator is cured, the light source is preferably ultraviolet light, visible light, or the like. The dose of light irradiation is preferably 500 to 1800mJ/cm2。
(8) Thermoplastic polymers
The curable resin composition I for liquid crystal sealing may further contain a thermoplastic polymer. The thermoplastic polymer is a polymer compound that softens when heated and can be molded into a desired shape.
The softening point temperature of the thermoplastic polymer applicable to the present invention is usually 50 to 120 ℃, preferably 60 to 80 ℃. When the softening point temperature is within the above range, the thermoplastic polymer melts in the resin composition during the thermosetting of the resin composition and is compatible with the acrylic resin (1), the modified epoxy resin (2), and the epoxy resin (6), whereby the decrease in viscosity of the composition during heating can be suppressed, and the leakage of liquid crystal and the like can be suppressed.
The content of the thermoplastic polymer is preferably 1 to 30 parts by mass per 100 parts by mass of the resin unit. The softening point temperature is measured by the ring and ball method (JACT test method: RS-2).
In addition, the thermoplastic polymer is desired to have an average particle diameter of usually 0.05 to 5 μm, preferably 0.07 to 3 μm, in order to exhibit good compatibility with the curable resin composition for a liquid crystal sealing agent. As such a thermoplastic polymer, a known polymer can be used, and a copolymer obtained by copolymerizing a (meth) acrylate monomer and a monomer copolymerizable with the (meth) acrylate monomer in an amount of 50 to 99.9 mass% to 50 to 0.1 mass% (more preferably 60 to 80 mass% to 40 to 20 mass%) is preferable. Further, the copolymer is preferably polymerized in an emulsion state by emulsion polymerization, suspension polymerization or the like.
Examples of the above-mentioned (meth) acrylate ester monomer include monofunctional (meth) acrylate ester monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl acrylate, 2-ethylhexyl (meth) acrylate, pentyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, butoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, and the like, or mixtures thereof. Among them, methyl (meth) acrylate, butyl acrylate, 2-ethylhexyl (meth) acrylate, or a mixture thereof is preferable.
Examples of the monomer copolymerizable with the (meth) acrylic acid ester monomer include acid monomers such as acrylamides, (meth) acrylic acid, itaconic acid and maleic acid, aromatic vinyl compounds such as styrene and styrene derivatives, conjugated dienes such as 1, 3-butadiene, 1, 3-pentadiene, isoprene, 1, 3-hexadiene and chloroprene, and polyfunctional monomers such as divinylbenzene and diacrylates. These may be used in combination.
(9) Other additives
The curable resin composition I for liquid crystal sealing may further contain additives such as a coupling agent such as a silane coupling agent, an ion scavenger, an ion exchanger, a leveling agent, a pigment, a dye, a plasticizer, and an antifoaming agent, if necessary. In addition, spacers and the like may be incorporated to adjust the gap of the liquid crystal display panel.
The second curable resin composition for liquid crystal sealing of the present invention is characterized by comprising, in addition to the thermal radical polymerization initiator (3) and the filler (4), a radical curable resin (10) having a radically polymerizable carbon-carbon double bond in 1 molecule and a radical chain transfer agent (11). The curable resin composition for liquid crystal sealing of the present invention having such characteristics is also referred to as "curable resin composition II for liquid crystal sealing" or "resin composition II".
Specific examples of (3) the thermal radical polymerization initiator and (4) the filler contained in the resin composition II are the same as those described above. Among them, the thermal radical polymerization initiator (3) of the resin composition II is particularly preferably an organic peroxide, an azo compound, benzoins, benzoin ethers, or acetophenones.
(10) Radically curable resin having radically polymerizable carbon-carbon double bond in 1 molecule
The radical-curable resin having a radically polymerizable carbon-carbon double bond in 1 molecule (may be simply referred to as "radical-curable resin") of the present invention refers to a compound having a radically polymerizable carbon-carbon double bond such as an ethylenically unsaturated bond in 1 molecule.
Examples of the radical curable resin include (meth) acrylate monomers or oligomers thereof, allyl alcohol derivatives, and vinyl compounds, and are not particularly limited. The above-mentioned (1) acrylic resin and (2) modified epoxy resin are included in the radical curable resin.
The (meth) acrylate monomer or its oligomer is not particularly limited, and includes, for example, those exemplified in the above (1) acrylic resin.
Examples of the above allyl alcohol derivatives include triallyl cyanurate, triallyl isocyanurate, diallyl maleate, diallyl adipate, diallyl phthalate, diallyl isophthalate, triallyl trimellitate, tetraallyl pyromellitate, glycerol diallyl ether, trimethylolpropane diallyl ether, pentaerythritol triallyl ether, allyl ester resins. Examples of the above vinyl compounds include divinylbenzene.
In addition, as the radical curable resin, a compound having 1 molecule and containing different kinds of functional groups such as a functional group having a carbon-carbon double bond and an epoxy group can be used. The carbon-carbon double bond is preferably a (meth) acryloyl group, and the different functional group is preferably an epoxy group. The radical-curable resin contains both an epoxy group and a (meth) acryloyl group in the resin skeleton, and therefore has high compatibility with other radical-curable resins and the above-mentioned (6) epoxy resin which can be an optional component of the composition II. Therefore, the composition containing the radical curable resin becomes homogeneous, the appearance of the seal is improved, and the adhesion reliability is good.
The number average molecular weight of the radical curable resin and the theoretical solubility parameter (sp value) of Fedors are also preferably within the same ranges as those of the acrylic resin (1) described above. That is, the number average molecular weight is in the range of 300 to 2000, and the theoretical solubility parameter is 10.0 to 13.0 (cal/cm)3)1/2. The radical-curable resin has low solubility and diffusivity for liquid crystal, and a composition containing the radical-curable resin can provide a liquid crystal display panel having good display characteristics. Further, since the radical curable resin has good compatibility with the epoxy resin (6), a homogeneous composition can be provided, and a resin composition having excellent adhesion reliability can be provided. The method for obtaining the number average molecular weight and the solubility parameter (sp value) is the same as the method mentioned in the description of the acrylic resin of the above (1), and therefore, the description thereof is omitted.
(11) Radical chain transfer agent
The radical chain transfer agent of the present invention is a compound which transfers a reactive active site by a chain transfer reaction in a radical polymerization reaction. The radical chain transfer agent (T) reacts with the growing radical (P. cndot.) as shown in the following formula (1) to form a new radical (T. cndot.) having a polymerization activity. The growth radical (P. cndot.) is a radical generated by adding a polymerizable compound to radicals generated by decomposition of an initiator one by one. The new radical (T. cndot.) thus generated reacts with the polymerizable compound (M) as shown in the following formula (2) to generate a growing radical (P1. cndot.).
On the other hand, as shown in the following formula (3), the growth radical reacts with the polymerizable compound to generate a growth radical P2. Assuming that the rightward growth rate constant at this time is KpAssuming that the rightward reaction rate constant of the following formula (1) is ktrIn order to cause radical chain transfer reaction, K is requiredp＜ktr. The details of the radical reaction described here are described in, for example, P38 of handbook for radical polymerization (ラジカル coincidence ハンドブツク) (1999).
Formula (1) P · + T → P + T ·
Formula (2) T · + M → P1 ·
Formula (3) P + M → P2 ·
As described above, the growing radical P generated in the curing reaction of the curable resin composition for liquid crystal sealing II of the present invention containing a radical chain transfer agent is more likely to cause the reaction of the formula (1) than the reaction of the formula (3). That is, the radical T. is easily generated. T is P1. produced by the reaction of the formula (2) with a polymerizable compound. P1. further, a new T.radical is generated by the reaction of the formula (1). Since the reactions of the formulae (1) and (2) proceed continuously, radicals such as T.cndot.P 1 are generated in a large amount in the liquid crystal sealing agent, and the curing reaction proceeds efficiently up to the corners of the liquid crystal sealing agent. As a result, the consumption rate of the polymerizable compound increases, the curing time of the liquid crystal sealant is shortened, and the amount of uncured polymerizable compound contained in the cured liquid crystal sealant decreases.
Examples of such radical chain transfer agents include i) thiols, ii) α -methylstyrene dimers, iii) terminally unsaturated methacrylates, iv) disulfides such as diphenyl disulfide, and v) porphyrin cobalt complexes (ポルフイリンコバルト mer).
i) Thiols
Among these, i) thiols are preferable as the radical chain transfer agent for the following reasons. Thiols are compounds containing thiol groups within 1 molecule. Since the thiol group is rich in reactivity, the carbon-carbon double bond of the radical curable resin of the above item (10) shows addition reactivity which other radical chain transfer agents do not have. Therefore, when a thiol group is used as the radical chain transfer agent, the addition reaction occurs in addition to the radical chain transfer reaction, and the curing speed of the liquid crystal sealing agent is further improved.
In addition, a thiol group also exhibits addition reactivity to an epoxy group. Therefore, as described later, the resin composition II of the present invention may further contain an epoxy group-containing compound such as the above-mentioned (6) epoxy resin in addition to the above-mentioned components, and the curing speed of such a resin composition II is further improved.
In addition, although the curing reaction accompanying the radical chain transfer reaction generally increases the curing rate, the molecular weight of the cured product may decrease. However, when a thiol is used as the radical chain transfer agent, the molecular enlargement effect of the cured product due to the addition reaction can be expected, and further effects such as improvement in the strength of the liquid crystal sealing agent after curing can be obtained.
Examples of the mercaptans which can be effectively used as the radical chain transfer agent include (i-1) mercaptoesters, (i-2) aliphatic polythiols, (i-3) aromatic polythiols, and (i-4) mercaptan-modified reactive silicone oils.
The mercapto ester (i-1) is an ester-based thiol compound obtained by reacting a mercapto carboxylic acid with a polyhydric alcohol. Next, the mercaptocarboxylic acids, the polyhydric alcohols, and the mercaptoesters effective for obtaining the mercaptoesters will be described.
Examples of the above-mentioned mercaptocarboxylic acids include mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, 2-mercaptoisobutyric acid, 3-mercaptoisobutyric acid. Examples of the above-mentioned polyhydric alcohols include ethylene glycol, propylene glycol, 1, 4-butanediol, 1, 6-hexanediol, glycerin, trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, 1, 3, 5-tris (2-hydroxyethyl) isocyanuric acid, sorbitol.
Examples of the above mercapto esters include trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate), and 2-ethylhexyl-3-mercaptopropionate.
(i-2) examples of the aliphatic polythiol group include decane thiol, ethane dithiol, propane dithiol, hexamethylene dithiol, decamethylene dithiol, diethylene glycol dithiol, triethylene glycol dithiol, tetraethylene glycol dithiol, thiodiethylene glycol dithiol, thiotriethylene glycol dithiol, thiotetraethylene glycol dithiol. In addition, cyclic sulfide compounds such as 1, 4-dithiane-containing cyclic polythiol compounds, episulfide resin-modified polythiols obtained by addition reaction of an episulfide resin and an active hydrogen compound such as amine, and the like are also included in aliphatic polythiols.
Examples of (i-3) the aromatic polythiol include benzylidene-2, 4-dithiol, ditolyldiol. In addition, (i-4) examples of the thiol-modified reactive silicone oils include mercapto-modified dimethylsiloxane and mercapto-modified diphenylsiloxane.
The above-mentioned thiols include primary thiols and secondary thiols. Primary thiols are thiol compounds in which 1 hydrocarbon group is bonded to the carbon to which the thiol group is bonded. A secondary thiol is a thiol compound having 2 hydrocarbon groups bonded to the carbon to which the thiol group is bonded.
When a primary thiol is used as the radical chain transfer agent, the addition reactivity with a carbon-carbon double bond group is excellent as described above, and thus there is an advantage that the physical properties of a cured product are excellent. However, since the reactivity is high, the storage stability of the liquid crystal sealing agent may be lowered. On the other hand, since the addition reactivity of the secondary thiol to the carbon-carbon double bond group is not as high as that of the primary thiol, the liquid crystal sealing agent has an advantage of excellent storage stability. Thus, secondary mercaptans are more preferred as the free radical chain transfer agent of the present invention. A liquid crystal sealing agent containing such a secondary thiol is particularly suitable as a so-called one-pack type liquid crystal sealing agent as described later.
Among them, the secondary thiol is preferably a thiol having 2 or more secondary thiol groups in a molecule and a number average molecular weight of 400 to 2000. When a liquid crystal sealing agent containing a radical chain transfer agent is cured, if the radical chain transfer agent does not enter a crosslinked material but remains as a monomer in the cured product, the radical chain transfer agent may dissolve and diffuse into the liquid crystal, and the display characteristics of the produced liquid crystal display panel may be degraded. On the other hand, a polyfunctional secondary thiol having a number average molecular weight of 400 to 2000 is easily incorporated into the crosslinked material. Therefore, the liquid crystal sealing agent containing the radical chain transfer agent is difficult to dissolve and diffuse into the liquid crystal, and thus the display characteristics of the manufactured liquid crystal display panel are good.
The secondary thiol is preferably a thiol obtained by reacting a secondary mercaptocarboxylic acid with a polyhydric alcohol, as described above. Examples of the secondary thiol having a number average molecular weight of 400 to 2000 include pentaerythritol tetrakis (3-mercaptobutanoate) (number average molecular weight 544.8) and 1, 3, 5-tris (3-mercaptobutyloxyethyl) -1, 3, 5-triazine-2, 4, 6(1H, 3H, 5H) -trione (number average molecular weight 567.7) described above. The number average molecular weight of the radical chain transfer agent can be measured, for example, by GPC using polystyrene as a standard.
Next, a chain transfer agent other than thiols will be described.
ii) alpha-methylstyrene dimers
The α -methylstyrene dimer is a compound having a reactive carbon-carbon double bond in 1 molecule and having a function as an addition-fragmentation chain transfer agent. Examples thereof include 2, 4-diphenyl-4-methyl-1-pentene, 2, 4-diphenyl-4-methyl-2-pentene and 1, 1, 3-trimethyl-3-phenylindane. The α -methylstyrene dimer of the present invention is not particularly limited, and known ones can be used.
iii) terminally unsaturated methacrylates
The terminally unsaturated methacrylate is a methacrylate compound having an unsaturated bond at the terminal and contributing to an addition reaction. Examples of such terminally unsaturated methacrylates include monomers, dimers, and n-polymers.
iv) disulfides
Examples of disulfides include diphenyl sulfide, polysulfide modified epoxy resins, diethoxymethane polysulfide polymers.
v) porphyrin cobalt complexes
Examples of porphyrin cobalt complexes include the tetrakistrimethylporphyrin CoIII complex, tetraphenylporphyrin CoIII complex. The Co complex may be Co-CH2C(CH3)3、Co-CH(CO2CH3)CH3、Co-CH(CO2CH3)CH2CH(CO2CH3)CH3。
The radical chain transfer agent may also be a chain transfer agent having the properties of an initiation-transfer-termination agent (iniferter). The initiation-transfer-terminator property refers to the property of realizing three functions of a free radical polymerization initiator, a free radical chain transfer agent and a free radical terminator. The radical chain transfer agent having such an initiation-transfer-termination agent property can cause the reverse reaction of the above formula (1) by applying light or thermal energy, and can improve the curability of the liquid crystal sealing agent while transferring the radical chain.
Examples of the radical chain transfer agent having the initiation-transfer-termination property include thiocarbamate-based compounds such as tetraethylthiuram disulfide, triphenylmethylazobenzene, tetraphenylethane derivatives.
The curable resin composition II for liquid crystal sealing may further include the epoxy curing agent (5), the epoxy resin (6), the photo radical polymerization initiator (7), the thermoplastic polymer (8), and other additives (9) in addition to the components (3), (4), (10), and (11). Details concerning these compounds and the like are the same as those already described, and explanation thereof is omitted here.
The amount of each component to be blended in the resin composition II is not particularly limited, but the content of the (3) thermal radical polymerization initiator is preferably 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the (10) radical-curable resin from the viewpoint of curability, storage stability and the like of the resin composition II. The resin composition II has good curability due to thermal radicals, and the cured product thereof has high adhesive strength with a substrate. However, when the content of (3) the thermal radical polymerization initiator is more than 5.0 parts by mass relative to (10) the radical curable resin, the viscosity stability of the resin composition II is deteriorated. On the other hand, when the content is less than 0.01 parts by mass, the amount of the thermal radical polymerization initiator is too small, and the curability of the resin composition II may be lowered.
The content of the radical chain transfer agent (11) is preferably 0.01 to 5.0 parts by mass, more preferably 0.05 to 3.0 parts by mass, relative to the radical curable resin (10). This resin composition II is excellent in viscosity stability, and when wiring on a substrate is complicated and fine, the curing reaction of the resin composition II proceeds sufficiently, and the uncured portion is extremely small, so that leakage of liquid crystal and contamination of liquid crystal can be suppressed. However, when the content of the (11) radical chain transfer agent is more than 5.0 parts by mass relative to the (10) radical curable resin, the curing reaction may not proceed properly, for example, the reaction between the (10) radical curable resin and the (6) epoxy resin proceeds excessively, and the viscosity stability may deteriorate. On the other hand, when the content of the (11) radical chain transfer agent is less than 0.01 part by mass, the effect of causing radical chain transfer is low, and the curability of the resin composition II may be lowered.
The content of the filler (4) is preferably 1 to 30 parts by mass, more preferably 5 to 25 parts by mass, per 100 parts by mass of the resin composition II. Although the resin composition II is useful as an inorganic filler from the viewpoint of improving moisture resistance, the resin composition II containing a large amount of an inorganic filler has a high viscosity and a low fluidity, and thus is difficult to be applied to a substrate, and the cured product of the resin composition II after curing may have a low curing strength. On the other hand, when the amount of the inorganic filler is small, the moisture resistance may be lowered. In this respect, the resin composition II in which the content of the inorganic filler is adjusted within the above range has high adhesive strength between the cured product and the substrate.
The content of the (5) epoxy curing agent is preferably 1 to 10 parts by mass, more preferably 2 to 5 parts by mass, per 100 parts by mass of the (10) radical-curable resin, from the viewpoint of further improving various properties such as curability and storage stability of the resin composition II. The resin composition II in which the content of the epoxy curing agent is adjusted within the above range can maintain excellent viscosity stability and can produce a liquid crystal display panel having high adhesion reliability. In addition, the content of the epoxy resin (6) in the resin composition II is preferably 1 to 40 parts by mass with respect to 100 parts by mass of the radical-curable resin (10).
The resin composition II preferably has a viscosity of 50 to 500 pas, more preferably 150 to 450 pas at 25 ℃ and 2.5rpm as measured by an E-type viscometer. The viscosity of the resin composition II can be appropriately adjusted depending on the blending amount of each component and the like. The viscosity (initial viscosity) of the resin composition II measured by an E-type viscometer at 25 ℃ and 2.5rpm is in the above range, so that coating unevenness does not occur on the substrate, and the coating workability is extremely good.
In particular, when the initial viscosity is 50 pas or more, the shape retention of the coated weather strip is particularly excellent. The seal strip shape retention property is a property of retaining the shape of the seal strip without changing even after the lapse of time from the coating. When the initial viscosity is 150 pas or more, the shape retention of the weather strip is more excellent. Further, if the initial viscosity is 450 pas or less, the coating workability is good even if the nozzle diameter is as small as 0.15 to 0.5mm when the liquid crystal sealing agent is coated by the dispenser.
The thixotropic index of the resin composition II, i.e., the ratio eta 1/eta 2 of the viscosity eta 1 at 25 ℃ and 0.5rpm to the viscosity eta 2 at 25 ℃ and 5.0rpm measured by an E-type viscometer, is preferably 1.1 to 5.0, more preferably 1.2 to 2.5. The viscosity of the resin composition II is a value measured by using an E-type rotational viscometer (for example, a digital rheometer manufactured by Bolefei, model DV-III ULTRA) and a CP-52 cone plate type sensor having a radius of 12mm and an angle of 3 ℃ for 5 minutes after the liquid crystal sealing agent is left at a predetermined temperature.
As described above, the thixotropic index is a ratio of a viscosity measured from a relatively low shear rate to a viscosity measured from a relatively high shear rate, so that a fluid having a high thixotropic index has a high viscosity at a low shear rate but exhibits a low viscosity at a high shear rate. Therefore, when the resin composition II is applied at a high shear rate, the viscosity of the resin composition II is low, and the coating property on the substrate is good. The seal bar portion formed of the resin composition II is less likely to cause liquid crystal leakage, and the resin composition II is excellent in defoaming property, so that the reliability of the manufactured liquid crystal display panel is excellent.
The third curable resin composition for liquid crystal sealing of the present invention is characterized by further comprising (12) a resin composition containing a radical polymerizable carbon-carbon double bond, a hydrogen bonding functional group and an epoxy group in addition to the above-mentioned (3) thermal radical polymerization initiator and (4) filler, the resin composition comprising two or more resins selected from the group consisting of the specific resins described later, and the amount of the hydrogen bonding functional group in the resin composition of (12) is 1.0 × 10-4～6.0×10-3mol/g, the amount of epoxy groups in the resin composition of the above (12) is 1.0X 10-4～2.6×10-3mol/g. The curable resin composition for liquid crystal sealing of the present invention having such characteristics is also referred to as "curable resin composition III for liquid crystal sealing" or "resin composition III".
(12) Resin composition containing radically polymerizable carbon-carbon double bond, hydrogen-bonding functional group, and epoxy group
The curable resin composition III for liquid crystal sealing of the present invention includes two or more resins selected from a specific group of resins, and includes a resin composition having a radically polymerizable carbon-carbon double bond, a hydrogen-bonding functional group, and an epoxy group (also simply referred to as "curable resin" in some cases).
A free-radically polymerizable carbon-carbon double bond refers to a functional group capable of undergoing polymerization by a free radical. Preferred examples of the radical polymerizable carbon-carbon double bond include vinyl group, allyl group, acryloyl group, methacryloyl group. Among them, the radical polymerizable carbon-carbon double bond is preferably a (meth) acryloyl group.
The hydrogen-binding functional group means a functional group or a binding group having hydrogen-binding property. Examples of the functional group having hydrogen bonding property include-OH group, -NH group2A group, -NHR group (R represents an aliphatic hydrocarbon group or an aromatic group), -CONH2Radical, -NH-radical, -NHOH radical. Examples of the binding group having hydrogen binding property include an-NHCO-binding group, -CONHCO-binding group, or-NH-binding group. Among them, the hydrogen-binding functional group in the present invention is preferably a hydroxyl group represented by-OH or a urethane-binding group represented by-NHCO- (which may be simply referred to as "urethane group").
The curable resin (12) contains a radically polymerizable carbon-carbon double bond such as a (meth) acryloyl group. Thus, the curable resin of (12) is included in the above-mentioned radical curable resin of (10).
As described above, the liquid crystal sealing agent is required to have excellent leakage resistance. Since liquid crystal tends to leak when the liquid crystal sealing agent is cured slowly, if a light shielding portion is present during curing with light, the liquid crystal leaks more significantly, and it is preferable that the liquid crystal sealing agent be cured only with heat. However, in general, the viscosity of the liquid crystal sealing agent is lowered during heat curing, and the liquid crystal leaks out even when the liquid crystal is cured by heat. Therefore, it is effective to reduce the viscosity reduction of the liquid crystal sealing agent when heated. In order to reduce the viscosity decrease of the liquid crystal sealing agent when heated, it is preferable to increase the curability of the curable resin contained in the liquid crystal sealing agent.
In this regard, the curable resin contained in the resin composition III has a 1.0 × 10-4～6.0×10-3The amount of hydrogen-binding functional groups in mol/g is high, and therefore, the curing speed is high. The mechanism is not clear, and it is assumed that when a certain amount of hydrogen-bonding functional groups are present, molecules of the curable resin are drawn together by hydrogen bonding and are present close to each other, and the curing reaction is more likely to proceed. In other words, it is considered that the reaction between the adjacent radical polymerizable carbon-carbon double bonds and the reaction between the adjacent epoxy groups are fast, and thus the curing speed of the curable resin of the present invention is fast.
The amount of the hydrogen-binding functional group is determined by dividing the amount of the hydrogen-binding functional group by the molecular weight of the radical-reactive resin, and the unit is mol/g. When the amount of the hydrogen-bonding functional group in the curable resin is greater than the above upper limit, the water resistance of a liquid crystal sealing agent containing the curable resin may be reduced. On the other hand, when the amount of the hydrogen-bonding functional group in the curable resin is less than the lower limit value, the curability of the liquid crystal sealing agent containing the curable resin is lowered. In this regard, the amount of the hydrogen-containing bonding functional group was 1.0X 10-4～6.0×10-3The liquid crystal sealing agent of the resin of mol/g has excellent balance between water resistance and curing property.
The hydrogen-binding functional group is also involved in contamination of the liquid crystal. In general, liquid crystals are hydrophobic and thus have difficulty in affinity with compounds having polar groups. In this regard, when the amount of the hydrogen-binding functional group in the compound is increased, the polarity of the compound becomes high, and it becomes difficult to have affinity with the liquid crystal. Thus, the amount of the hydrogen-containing functional group is 1.0X 10-4～6.0×10-3A liquid crystal sealing agent containing a curable resin in a mol/g ratio hardly contaminates a liquid crystal.
As described above, the curable resin of the present invention has an epoxy group in a molecule. The epoxy group means a group represented by the following structural formula.
[ solution 5]
The amount of epoxy groups in the curable resin of the present invention is 1.0X 10-4～2.6×10-3mol/g. The epoxy group amount is determined by dividing the number of epoxy groups by the molecular weight of the curable resin, and the unit is mol/g. Since the epoxy group has high addition polymerizability, the curable resin having an epoxy group has high curability. Further, the epoxy group improves the adhesion between the liquid crystal sealing agent and the glass substrate.
The curable resin of the present invention is obtained by blending two or more resins selected from the group consisting of the resins shown below.
(1A) Has a hydrogen-bonding functional group and 2 carbon-carbon double bonds capable of free radical polymerization in the molecule, and the amount of the hydrogen-bonding functional group is 1.5X 10-3～6.0×10-3mol/g of a free radical reactive resin;
(1B) has a hydrogen-bonding functional group, an epoxy group and a radically polymerizable carbon-carbon double bond in a molecule, and the amount of the hydrogen-bonding functional group is 1.0X 10-4～5.0×10-3mol/g of a free radical reactive resin;
(1C) an epoxy resin having an epoxy group in the molecule but no radically polymerizable carbon-carbon double bond, a softening point of 40 ℃ or higher as measured by a ring and ball method, and a weight average molecular weight of 500 to 5000
The curable resin of the present invention is compounded by appropriately selecting the resins (1A) to (1C), and the amount of the hydrogen-bonding functional group and the amount of the epoxy group are adjusted within the above ranges. The amount of the hydrogen-bonding functional group in the curable resin of the present invention containing the resins (1A) to (1C) is determined as follows.
Assuming that the number of hydrogen-binding functional groups of (1A) is Na (n), the molecular weight is Ma (g/mol), the compounding ratio is a (mass%), (1B) is Nb (n), the molecular weight is Mb (g/mol), the compounding ratio is B (mass%), (1C) is Nc (n), the molecular weight is Mc (g/mol), and the compounding ratio is C (mass%), the amount of hydrogen-binding functional groups of the curable resin is determined by the following formula.
Amount of hydrogen-bonding functional group of curable resin
(Na)/(Ma)×a/100+(Nb)/(Mb)×b/100+(Nc)/(Mc)×c/100
The epoxy group content of the curable resin was also determined in the same manner.
The resins (1A) to (1C) will be described below.
(1A) Of (2) a resin
(1A) The resin (2) has a hydrogen-bonding functional group and a radically polymerizable 2-carbon double bond in the molecule, and the amount of the hydrogen-bonding functional group is 1.5X 10-3～6.0×10-3mol/g resin. In the present invention, the 2 carbon-carbon double bonds capable of radical polymerization are also simply referred to as "double bonds", and the resin of (1A) is sometimes referred to as "radical bifunctional resin". The free radical difunctional resin preferably does not contain epoxy groups.
The hydrogen-bonding functional group of the radical bifunctional resin was determined as described above. Its value is 1.5X 10-3～6.0×10-3mol/g, preferably 1.5X 10-3～3.4×10-3mol/g. The molecular weight of the radical bifunctional resin used for calculation of the amount of the hydrogen-bonding functional group is preferably determined by conversion to polystyrene by GPC. In this case, the number average molecular weight and the weight average molecular weight are calculated, and the amount of the hydrogen-binding functional group is preferably calculated from the number average molecular weight.
The radical bifunctional resin is obtained, for example, by subjecting a "compound having a double bond and a carboxylic acid in a molecule" and a "compound having a double bond and a hydroxyl group in a molecule" to an esterification reaction.
Examples of the "compound having a double bond and a carboxylic acid in the molecule" include (meth) acrylic acid, and a (meth) acrylic acid derivative obtained by reacting (meth) acrylic acid with an acid anhydride. The "compound having a double bond and a carboxylic acid in the molecule" may be a compound obtained by adding 6-caprolactone to hydroxyalkyl acrylate and further reacting the compound with an acid anhydride. Examples of hydroxyalkyl acrylates include hydroxyethyl acrylate, hydroxybutyl acrylate.
Examples of the "compound having a double bond and a hydroxyl group in the molecule" include hydroxyalkyl acrylates, 4-pentaerythritol tri (meth) acrylate, sorbitol tri (meth) acrylate.
The radical bifunctional resin can also be obtained by a ring-opening addition reaction of a carboxyl group of a "compound having a double bond and a carboxylic acid in a molecule" and an epoxy group of an "aromatic diol-based polyglycidyl ether compound".
Examples of the "polyglycidyl ether compound of an aromatic diol" include polyglycidyl ether compounds of bisphenol A, bisphenol S, bisphenol F, bisphenol AD, diphenyl ether, resorcinol, and the like.
Among them, the radical bifunctional resin is preferably a resin obtained by the reaction of a polyglycidyl ether compound and (meth) acrylic acid, and more preferably a resin represented by the following general formulae (a1) to (a4), or a mixture thereof.
[ solution 6]
General formula (a 1):
r in the formula (a1)1、R2、R3、R4Each independently represents a hydrogen atom or a methyl group, RmEach independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group, a hydroxyalkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, n represents an integer of 1 to 4, l represents an integer of 1 to 4, A represents a group represented by-CH2-、-C(CH3)2-、-SO2-or-O-represents an organic group.
[ solution 7]
General formula (a 2):
r in the formula (a2)5、R6、R7、R8Each independently represents a hydrogen atom or a methyl group, RqIndependently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group, a hydroxyalkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, r represents an integer of 1 to 4, and p represents an integer of 1 to 4.
[ solution 8]
General formula (a 3):
r in the formula (a3)1、R2、RmN and A are as defined for formula (a 1).
[ solution 9]
General formula (a 4):
r in the formula (a4)5、R6Is defined by the formula(a2) The same as in (1).
Among them, the radical bifunctional resin of the present invention is particularly preferably a resin represented by the general formula (a3) or (a 4).
(1B) Of (2) a resin
(1B) The resin (2) has a hydrogen-bonding functional group, an epoxy group and a double bond in a molecule, and the amount of the hydrogen-bonding functional group is 1.0X 10-4mol/g～5.0×10-3mol/g resin. (1B) The resin of (2) is obtained by reacting an epoxy group of the epoxy resin with a carboxyl group of (meth) acrylic acid or a derivative thereof.
(1B) The amount of the hydrogen-bonding functional group of the resin (3) is determined as described above. The preferred value of the amount of the hydrogen-binding functional group is 1.0X 10-4～5.0×10-3mol/g, more preferably 1.0X 10-4～3.4×10-3mol/g. The molecular weight used for determining the amount of the hydrogen-bonding functional group is preferably a number average molecular weight determined by GPC, similarly to the radical bifunctional resin.
(1B) The epoxy group content of the resin (A) is not particularly limited, but is preferably 1.0X 10-4～6.0×10-3mol/g, more preferably 1.0X 10-4～3.5×10-3mol/g。
(1B) The number average molecular weight of the resin (C) is preferably 300 to 2000. When the number average molecular weight is within this range, the solubility and diffusivity of the curable resin to the liquid crystal are low. Therefore, the liquid crystal sealing agent containing the resin hardly contaminates the liquid crystal.
Examples of the epoxy resin to be a raw material of the resin (1B) include cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol a type epoxy resin, bisphenol F type epoxy resin, triphenol methane type epoxy resin, triphenol ethane type epoxy resin, triphenol type epoxy resin, dicyclopentadiene type epoxy resin, biphenyl type epoxy resin. These epoxy resins are preferably purified by a molecular distillation method, a washing method, or the like.
Examples of the (meth) acryloyl derivative which becomes the raw material of the resin of (1B) include compounds having a group reactive with an epoxy group and a (meth) acryloyl group. Specific examples of such a compound include compounds having a carboxyl group as a reactant of a polycarboxylic acid and a hydroxy (meth) acrylate.
Specific examples of the polycarboxylic acid include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, succinic anhydride, maleic anhydride, fumaric acid, adipic anhydride, 4- (meth) acryloyloxyethyl trimellitic anhydride.
Specific examples of the hydroxy (meth) acrylates include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, an ethylene oxide adduct of (meth) acrylic acid, a propylene oxide adduct of (meth) acrylic acid, and a caprolactone-modified product of (meth) acrylic acid.
(1B) The resin (2) has both an epoxy group and a double bond in the molecule, and thus has excellent compatibility with the (1A) radical bifunctional resin and the (1C) epoxy resin. Therefore, a liquid crystal sealant comprising the resin of (1B) and the radical bifunctional resin of (1A) or the epoxy resin of (1C) can provide a uniform cured product. Such a liquid crystal sealing agent has a high glass transition temperature (Tg) and high adhesive strength.
(1C) Of (2) a resin
(1C) The resin (2) has not an ethylenically unsaturated double bond in the molecule but 1 or more epoxy groups. The epoxy resin has a softening point of 40 ℃ or higher measured by a ring and ball method, and has a weight average molecular weight of 500-5000.
(1C) The softening point and molecular weight of the resin (b) have an influence on the viscosity of the liquid crystal sealing composition. The viscosity of the curable resin in the liquid crystal sealing agent containing the resin having the softening point and the weight average molecular weight of (1C) within the above ranges is not excessively low, and is within an appropriate range, and thus the seal pattern is less likely to be deformed and has excellent leakage resistance. The softening point is not particularly limited as long as it is 40 ℃ or higher, but it is preferably 160 ℃ or lower in order to keep the viscosity in the liquid crystal sealing agent within an appropriate range.
In addition, since the liquid crystal sealing agent containing the resin (1C) having the softening point and the weight average molecular weight within the above ranges has low solubility and diffusibility in liquid crystal, the resin (1C) is less likely to contaminate the liquid crystal. (1C) The weight average molecular weight of the resin (2) can be measured by GPC using polystyrene as a standard, for example.
Examples of the resin of the above (1C) include the following resins having a softening point and a weight average molecular weight within the above ranges.
Aromatic polyglycidyl ether compounds obtained by reacting epichlorohydrin with aromatic diols represented by bisphenol a, bisphenol S, bisphenol F, bisphenol AD, and the like, or diols obtained by modifying these with ethylene glycol, propylene glycol, or alkylene glycol.
A novolak-type polyglycidyl ether compound obtained by reacting a novolak resin derived from phenol or cresol and formaldehyde, or a polyphenol represented by a polyalkenylphenol and a copolymer thereof, with epichlorohydrin.
Glycidyl ether compounds of xylyl phenol resins.
Specific examples of the novolak type polyglycidyl ether compound include cresol novolak type epoxy resins and phenol novolak type epoxy resins. Specific examples of the aromatic polyglycidyl ether compound include bisphenol a type epoxy resin, bisphenol F type epoxy resin, triphenolmethane type epoxy resin, triphenolethane type epoxy resin, triphenolic type epoxy resin, dicyclopentadiene type epoxy resin, diphenyl ether type epoxy resin, biphenyl type epoxy resin.
(1C) The epoxy group amount of the resin (2) is determined by dividing the number of epoxy groups by the molecular weight of the resin (1C) in the same manner as the resin (1B). The molecular weight is preferably determined from the epoxy equivalent weight. (1C) The same applies to the method for determining the amount of the hydrogen-bonding functional group in the case where the resin (2) has the hydrogen-bonding functional group.
The amount of epoxy groups is equal to the reciprocal of the epoxy equivalent, and can be determined by measuring the epoxy equivalent of the resin of (1C). The epoxy equivalent can be calculated from the amount of hydrochloric acid consumed by the sample by dissolving the sample in dioxane, adding a hydrochloric acid-dioxane solution, standing, adding a mixed solution of ethanol and toluene, and using cresol red as an indicator.
A liquid crystal sealing agent including a curable resin composed of the resin of (1A) and the resin of (1C) is particularly excellent in the balance between leakage resistance and adhesive strength. Further, a liquid crystal sealing agent including a curable resin composed of the resin of (1B) and the resin of (1C) is particularly excellent in adhesive strength. Further, a liquid crystal sealing agent including a curable resin composed of the resin of (1A) and the resin of (1B) is particularly excellent in leakage resistance.
In the case where the liquid crystal sealing agent includes the resin (1A) and the resin (1C) as the curable resin, the mixing ratio of the resin (1A) and the resin (1C) is preferably 70 to 97: 30 to 3 in terms of mass ratio. When the liquid crystal sealing agent comprises the resin (1A) and the resin (1B) as curable resins, the mixing ratio of the resin (1A) and the resin (1B) is preferably 10-70: 90-30 by mass. When the liquid crystal sealing agent comprises the resin (1B) and the resin (1C) as the curable resin, the mixing ratio of the resin (1B) and the resin (1C) is preferably 70-97: 30-3 by mass. When the liquid crystal sealing agent comprises the resin (1A), the resin (1B) and the resin (1C) as the curable resin, the mixing ratio of the resin (1A), the resin (1B) and the resin (1C) is preferably 10-87: 3-30 by mass ratio.
The curable resin composition III for liquid crystal sealing may further include the epoxy curing agent (5), the epoxy resin (6), the photo radical polymerization initiator (7), the thermoplastic polymer (8), and other additives (9) in addition to the above-described components (3), (4), and (12). Details concerning these compounds and the like are the same as those described above, and the description thereof is omitted here.
2. Method for producing curable resin composition for sealing liquid crystal
The curable resin composition for liquid crystal sealing of the present invention can be produced arbitrarily, for example, by mixing the components described above, within a range not impairing the effects of the present invention. The mixing method is not particularly limited, and known mixing equipment such as a double-blade mixer, a roll mixer, a twin-screw extruder, a ball mill mixer, and a planetary mixer can be used. The roll temperature is preferably set to 15 to 35 ℃ and more preferably 25 to 35 ℃ in order to uniformly knead the mixture without gelling the mixture. In view of improving the viscosity stability of the composition, the temperature of the mixture during preparation is preferably in the range of 15 ℃ to 30 ℃. The finally obtained mixture was filtered with a filter as needed, vacuum defoamed, and then hermetically filled in a glass bottle or a plastic container.
3. Method for manufacturing liquid crystal display panel
The liquid crystal display panel of the present invention can be produced using the curable resin composition for liquid crystal sealing of the present invention, and a preferred production method will be described below.
The method for manufacturing a liquid crystal display panel is a method for manufacturing a liquid crystal display panel in which 2 substrates facing each other are bonded to each other with a curable resin composition for liquid crystal sealing, and is characterized by comprising:
1) a step of preparing a1 st substrate including a frame-shaped display region in which a pixel array region is surrounded by the curable resin composition for sealing liquid crystal according to the present invention;
2) dropping a liquid crystal into the display region in an uncured state or into another substrate;
3) a step of superposing the 1 st substrate and the 2 nd substrate opposed thereto; and
4) and curing the liquid crystal sealing resin composition by heating.
In the step 1), a substrate on which a frame-shaped display region is arranged is prepared by applying a liquid crystal sealing agent to any of 2 substrates. The frame-shaped display region refers to the shape of the weatherstrip drawn by the resin composition, and is also referred to as a seal pattern. The substrate is a member constituting the base of the display panel, and is generally made of 2 sheets of glass or the like. Examples of the 2-piece substrate used for the liquid crystal display panel include a glass substrate in which TFTs are formed in a matrix shape, and a substrate in which color filters and black matrices are formed. Examples of the material of the substrate include glass, and plastics such as polycarbonate, polyethylene terephthalate, polyether sulfone, and PMMA.
An alignment film may be formed on the opposing surface of each substrate. The alignment film is not particularly limited, and for example, an alignment film made of a known organic alignment agent or inorganic alignment agent can be used. The spacers may be dispersed in advance on the substrate. The spacers are generally spherical silica particles, and are effective in uniformly maintaining the cell gap. In-plane spacers in a state of being dispersed on a substrate in advance or spacers included in a liquid crystal sealant are generally used. The type and size of the spacer are not particularly limited, and a known spacer may be used according to the desired size of the cell gap.
Examples of the method of applying the liquid crystal sealing agent on the substrate include application by a dispenser, application by screen printing, and the like, and there is no particular limitation, and a known technique can be used. In the case of manufacturing a small-sized liquid crystal display panel, application by screen printing is preferable from the viewpoint of improving productivity.
In the step 2), a proper amount of liquid crystal is dropped into the uncured display region or the other substrate. The "uncured state" means a state in which the curing reaction of the resin composition does not proceed to the gelation point. The liquid crystal dropping is usually carried out under atmospheric pressure.
The dropping amount of the liquid crystal is preferably adjusted according to the size of the frame so that the liquid crystal is accommodated in the frame. Thus, the capacity of the liquid crystal does not exceed the capacity of the space (cell) surrounded by the liquid crystal sealant existing between the 2 substrates, so that excessive pressure is not applied to the frame, and the seal tape for manufacturing the frame is not broken. In the case of dropping the liquid onto the other substrate on which the display region is not formed in the step (2), the liquid may be dropped into a region which can be a display region when the substrates are stacked.
In the step 3), the substrate to which the liquid crystal is dropped is overlapped with another substrate. In the lamination, since the substrates are bonded to each other by a difference in air pressure, it is preferable to perform the lamination under reduced pressure using a vacuum bonding apparatus or the like.
The step 3) may be followed by a step of returning the stacked 2 substrates from a reduced pressure to an atmospheric pressure. When the two substrates stacked under reduced pressure are returned from the reduced pressure to the atmospheric pressure environment, a pressure difference is generated between the inside and the outside of the frame, and 2 substrates are pressed from the outside, and the two substrates are bonded.
In the step 4), the liquid crystal sealing agent located between the substrates is cured. The liquid crystal sealant of the present invention can be rapidly cured only by heating. The curing conditions such as heating temperature and time may be appropriately selected depending on the composition of the liquid crystal sealing agent. 4) The step (2) may include a step of curing the liquid crystal sealing agent by irradiating light. In this case, the liquid crystal sealing agent may be once cured by light irradiation and then post-cured by heating. The light irradiation means irradiation of light (preferably ultraviolet light) having energy capable of reacting the curable resin. From the viewpoint of simplifying the steps in manufacturing the panel, the step of 4) is preferably a step of curing the liquid crystal sealing agent only by heating.
In the case where the liquid crystal sealing agent is cured only by heating in the step 4), the heating condition is preferably 80 to 150 ℃ for 10 to 240 minutes, more preferably 100 to 130 ℃ for 30 to 120 minutes. On the other hand, when the curing is carried out by irradiation with light and heating, the heating condition is preferably 40 to 90 ℃ for 1 to 120 minutes. In any case, the post-curing may be carried out at 110 to 150 ℃ for 30 to 90 minutes as required.
In addition, in recent liquid crystal dropping methods, the following methods are employed for further improving productivity: after a plurality of frames are formed on the substrates by the liquid crystal sealing agent, an appropriate amount of liquid crystal is dropped into each frame or the pair of substrates, and then 2 substrates are attached to each other. This method is effective also in cutting out the respective liquid crystal display panels by cutting the outer periphery of the frame after the substrates are bonded to each other.
The liquid crystal sealing agent of the present invention is cured quickly and sufficiently by heating without using light. Therefore, there is no need to consider the problem of the uncured portion remaining in the light shielding portion, and the restrictions on the panel design are also very small. Further, since it is not necessary to use an ultraviolet irradiation device or the like for curing the liquid crystal sealing agent, the manufacturing cost can be reduced. Further, since the liquid crystal sealing agent of the present invention contains a predetermined thermal radical polymerization initiator and a chain transfer agent as in the above compositions I to III, when the liquid crystal sealing agent is heated, the curing proceeds sufficiently in a short time after the activation of radicals and the like. Therefore, even when a liquid crystal display panel having a complicated black matrix and wiring is manufactured, such as a small panel mounted on a mobile phone, there is no problem that the light shielding portion has an uncured portion.
Here, the black matrix is defined by a photoresist, and includes a lattice-shaped outline surrounding the 3 primary colors of light constituting the color filter, R (red), G (green), and B (blue). Also, the means for ultraviolet irradiation or heating is not particularly limited. Examples of heating devices that can be used in the present invention include ovens, hot plates, and hot presses.
In the above method, the liquid crystal display panel produced using the curable resin composition for liquid crystal sealing of the present invention has excellent leakage resistance, is suppressed in liquid crystal contamination, and has good display characteristics because the cured product of the liquid crystal sealing agent has high adhesion strength to the substrate.
Examples
The present invention will be described in more detail below with reference to examples and comparative examples related to the present invention. However, the present invention is not limited to the embodiment illustrated herein. In addition, "%" and "part" described below mean "% by mass" and "part by mass", respectively.
First, examples and comparative examples of the curable resin composition I for liquid crystal sealing of the present invention will be described.
[ preparations of materials used in examples I-1 to 13 and comparative examples I-1 to 4]
(1) Acrylic resin
The following resin was diluted with toluene, washed with ultrapure water, and the process was repeated 12 times to carry out a high-purity treatment.
Acrylic resin 1: bisphenol A epoxy resin-modified diacrylate (3002A, molecular weight 600, chemical Co., Ltd.)
Acrylic resin 2: bisphenol A epoxy resin-modified diacrylate (EB 3700: 485 molecular weight, manufactured by DAICEL-CYTEC Co., Ltd.)
(2) Modified epoxy resin
A modified epoxy resin synthesized by the following method was prepared (Synthesis example I-1).
[ Synthesis example I-1]
160g of bisphenol F type epoxy resin (EPOTETYDF-8170C, manufactured by Tokyo chemical Co., Ltd.), 36g of acrylic acid and 0.2g of triethanolamine were charged into a 500ml four-necked flask equipped with a stirrer, a gas inlet, a thermometer and a condenser, and heated and stirred at 110 ℃ for 5 hours under a dry air flow to obtain an acrylic acid-modified epoxy resin. The obtained resin was washed with ultrapure water 12 times.
(3) Thermal radical polymerization initiator
Thermal radical polymerization initiator 88: 1, 1-azobis (2, 4-cyclohexane-1-carbonitrile) (V-40: manufactured by Wako pure chemical industries, 10-hour half-life temperature 88 ℃ C.)
Thermal radical polymerization initiator 75: tert-amyl peroxy-2-ethylhexanoate (Lupasol 575: 75 ℃ C. 10-hour half-life temperature, manufactured by API Co., Ltd.)
Thermal radical polymerization initiator 65: 2, 2' -azobis (2-methylpropionate) (V-601: manufactured by Wako pure chemical industries, 10-hour half-life temperature 65 ℃ C.)
Thermal radical polymerization initiator 51: 2, 2' -azobis (2, 4-dimethylvaleronitrile) (V-65: manufactured by Wako pure chemical industries, 10-hour half-life temperature 51 ℃ C.)
(4) Filler material
Packing 1: spherical silica (Seahostar, シ - フオスタ one) S-30: produced by Japanese catalyst, having an average primary particle diameter of 0.3 μm and a specific surface area of 11m2/g)
And (3) filler 2: spherical silica (SO-C2: manufactured by Admatechs Co., Ltd., average primary particle diameter 0.9 μm, specific surface area 4m2/g)
(5) Epoxy curing agent
Latent epoxy curing agent 1: 1, 3-bis (hydrazinocarbonylethyl) -5-isopropylhydantoin (AmicureVDH: Melonin Co., Ltd., melting point 120 ℃ C.)
Latent epoxy curing agent 2: adipic acid dihydrazide (ADH: melting point 181 ℃ C., manufactured by Otsuka chemical Co.)
(6) Epoxy resin
Epoxy resin 1: o-cresol novolac type solid epoxy resin (EOCN-1020-75: 75 softening point of 75 ℃ and epoxy equivalent of 215g/eq, measured by the Ring and ball method, manufactured by Nippon chemical Co., Ltd.)
Epoxy resin 2: bisphenol A type epoxy resin (EPIKOTE 828 EL: JER, epoxy equivalent 190g/eq)
(7) Photo-radical polymerization initiator
Photo radical polymerization initiator 1: 1-Hydroxycyclohexyl phenyl ketone (Irgacure 184: manufactured by Ciba specialty Co., Ltd.)
Photo radical polymerization initiator 2: 2, 2-dimethoxy-2-phenylacetophenone (Irgacure 651: manufactured by Ciba specialty Chemicals Co., Ltd.)
(8) Thermoplastic polymers
Alkyl methacrylate copolymer particles (F-325: 0.5 μm average primary particle diameter, manufactured by ZEON, Japan) were prepared.
[ evaluation method ]
The evaluation methods performed in examples I-1 to 13 and comparative examples I-1 to 4 will be described. Here, i) viscosity measurement, ii) leakage resistance of the liquid crystal sealing agent, iii) coatability of the liquid crystal sealing agent, and iv) adhesive strength were measured, and characteristics of the liquid crystal sealing agent were evaluated. Details of each measurement and evaluation method are as follows.
i) Viscosity measurement
The measurement was performed under the following conditions using an E-type rotary viscometer (digital rheometer, model DII-III ULTRA: manufactured by Boleyawa Co.) and a CP-52 type cone-plate sensor having a radius of 12mm and an angle of 3 degrees at 1.0 rpm.
Viscosity at 25 ℃: the liquid crystal sealant of the present invention was left at 25 ℃ for 5 minutes and then measured.
Viscosity at 80 ℃: the liquid crystal sealing agent of the present invention was placed in a cup of an E-type rotational viscometer, heated to 80 ℃ at a heating rate of 5 ℃/min, and left at 80 ℃ for 5 minutes, and then measured.
In the above-mentioned measurement method, the viscosity of the liquid crystal sealing agent at 80 ℃ is not measured when it exceeds the measurement limit, and the measurement is carried out by the parallel plate method (RheoStress RS 150: manufactured by HAAKE). Measurement by the parallel plate method was carried out immediately after the temperature was raised to 80 ℃ at a temperature raising rate of 5 ℃ per minute according to the standard method of the above-mentioned model.
ii) leakage resistance of liquid Crystal sealant
A liquid crystal sealing agent to which 1 part of 5 μm glass fiber was added was drawn as a 35mm x 40mm frame shape with a line width of 0.5mm and a thickness of 50 μm on a 40mm x 45mm glass substrate (RT-DM88 PIN: manufactured by EHC) with a transparent electrode and an alignment film by using a dispenser (manufactured by SHOTMASTER GmbH).
Next, a liquid crystal material (MLC-11900:. 000: Merck) was precisely dropped by a dispenser in an amount corresponding to the content of the pasted panel. Subsequently, the opposed glass substrates were stacked under a reduced pressure of 90Pa, fixed by applying a load, and cured by heating at 120 ℃ for 60 minutes after opening the atmosphere.
The sealing linearity of the obtained liquid crystal display panel was evaluated according to the following criteria.
[ ratio of maximum width to minimum width of weatherstrip ]% ([ minimum width of weatherstrip ]/[ maximum width of weatherstrip ] × 100%
The above ratio is 95% or more: o (Excellent)
50% or more and less than 95%: delta (slightly good)
Less than 50% of cases: x (poor)
iii) coatability of liquid crystal sealing agent
A glass substrate for a liquid crystal display panel (manufactured by Nippon electric glass Co., Ltd.) having a tip diameter of 0.4mm was filled with a liquid crystal sealing agent containing 1% 5 μm glass fibers under vacuum. Next, 50 frame shapes of 35mm by 40mm were drawn by a dispenser (SHOTMASTER, manufactured by Shottes high-tech Co., Ltd.) under conditions of a discharge pressure of 0.3MPa, a coating thickness of 20 μm, and a coating speed of 100 mm/sec.
The seal shape of the drawn seal pattern was evaluated by the following criteria.
The number of frame types which do not generate seal interruption and seal flash at all is 48-50: o (Excellent)
The number of the frame shapes is more than 45 and less than 48: delta (slightly good)
The number of the frame types is less than 44: x (poor)
iv) adhesive strength
A liquid crystal sealing agent containing 1% of 5 μm glass fibers was screen-printed on an alkali-free glass having a diameter of 1mm in a circular shape of 25 mm. times.45 mm. times.5 mm in thickness, and the same glass was bonded to each other and heated at 120 ℃ for 1 hour while fixing, to prepare an adhesion test piece. The obtained test piece was peeled off at a speed of 2mm/min in a direction parallel to the bottom surface of the glass using a tensile tester (model 210: manufactured by Institox corporation), and the in-plane tensile strength was measured.
The adhesive strength was evaluated according to the following criteria.
Tensile strength of 10MPa or more: o (Excellent)
A tensile strength of 7MPa or more and less than 10 MPa: delta (slightly good)
Tensile strength less than 7 MPa: x (poor)
[ example I-1]
30 parts of acrylic resin 1, 70 parts of the methacrylic-modified epoxy resin obtained in Synthesis example I-1, 1 part of a thermal radical polymerization initiator 75 having a 10-hour half-life temperature of 75 ℃ and 20 parts of a filler 1 were premixed in a mixer, and then kneaded with a three-roll mill until the solid material became 5 μm or less. Subsequently, the composition was filtered through a filter having a pore size of 10 μm (MSP-10-E10S: manufactured by ADVANTEC) and subjected to vacuum defoaming treatment to obtain a resin composition for sealing liquid crystals.
The viscosity at 25 ℃ of the obtained resin composition for liquid crystal sealing was 260 pas at 0.5rpm, 180 pas at 1.0rpm, and 120 pas at 5 rpm.
The viscosity of the E-type rotary viscometer at 80 ℃ exceeded 780 pas, and was measured by the parallel plate method (RheoStress RS 150: manufactured by HAAKE), and was 9.00E +05 pas. In addition, the thixotropic index was 2.2.
Subsequently, the respective measurements of the resin composition for liquid crystal sealing were carried out by the above-mentioned evaluation methods, and the characteristics thereof were evaluated.
[ examples I-2 to 13]
A resin composition for sealing liquid crystal having the composition shown in Table 1 and Table 2 was obtained in the same manner as in example I-1. Further, the same evaluation as in example I-1 was carried out.
Comparative examples I-1 to 2
A resin composition for liquid crystal sealing having a composition shown in table 3 was obtained in the same manner as in example 1. Further, the same evaluation as in example 1 was performed.
Comparative example I-3
60 parts of acrylic resin 2 and 40 parts of epoxy resin 2 were mixed and stirred by a planetary stirring apparatus.
Subsequently, 2 parts of photo radical polymerization initiator 2, 10 parts of thermoplastic polymer, 1 part of silane coupling agent (S510: manufactured by Chilean corporation), 10 parts of filler 2, and 10 parts of latent epoxy curing agent 2 were further added to the resin, and mixed and stirred by a planetary stirring device. Subsequently, the mixture was mixed by a ceramic three-roll mill to obtain a resin composition for sealing liquid crystal. The obtained resin composition was evaluated in the same manner as in example 1.
Comparative example I-4
60 parts of acrylic resin 2 and 40 parts of epoxy resin 2 were mixed and stirred by a planetary stirring apparatus.
Then, 10 parts of a thermoplastic polymer, 1 part of a silane coupling agent (S510: manufactured by Chilean corporation), 10 parts of a filler 2, and 10 parts of a latent epoxy curing agent 2 were further blended with the resin, and mixed and stirred by a planetary stirring device. Subsequently, the mixture was further mixed by a ceramic three-roll mill to obtain a resin composition for liquid crystal sealing. The obtained resin composition was evaluated in the same manner as in example 1.
The results of the leakage property, coating property and adhesive strength of the sealants for liquid crystal dropping methods prepared in examples I-1 to 13 and comparative examples I-1 to 4 are shown in tables 1 to 3.
TABLE 1
TABLE 2
TABLE 3
The liquid crystal sealing agents shown in examples I-1 to 13 were excellent in the leakage resistance, the coatability and the adhesive strength. When these results are compared with the results of comparative examples I-1, 3 and 4, it is found that the liquid crystal sealing agent has a viscosity of 500 pas or less at 80 ℃ and a problem in the leakage resistance is caused. Further, when the example is compared with comparative example I-2, it is understood that if the viscosity at 25 ℃ and 1.0rpm is more than 500 pas and the thixotropic index is more than 5, a problem occurs in coatability. Further, it is understood from the results of examples I-1 to 13 and comparative examples I-3 and 4 that when the content of the filler is small, the adhesive strength becomes problematic.
Next, examples and comparative examples of the curable resin composition II for liquid crystal sealing of the present invention will be described.
Examples II-1 to 6 and comparative examples II-1 and 2
The materials used in the examples and the like are as follows.
(3) Thermal radical polymerization initiator
Thermal radical polymerization initiator: 2, 2' -azobis (2-methylpropionate) (trade name V-601 manufactured by Wako pure chemical industries, 10-hour half-life temperature 65 ℃ C.)
(4) Filler material
Filling: spherical silica (Xifosta S-30: manufactured by Japan catalyst, average primary particle diameter 0.3 μm, specific surface area 11m2/g)
(5) Epoxy curing agent
Heat latent epoxy curing agent: 1, 3-bis (hydrazinocarbonylethyl) -5-isopropylhydantoin (AmicureVDH: Melonin Co., Ltd., melting point 120 ℃ C.)
(6) Epoxy resin
Epoxy resin: o-cresol novolac type solid epoxy resin (EOCN-1020-75: 75 softening point of 75 ℃ and epoxy equivalent of 215g/eq, measured by the Ring and ball method, manufactured by Nippon chemical Co., Ltd.)
(9) Other additives
Silane coupling agent (gamma-glycidoxypropyltrimethoxysilane KBM-403 manufactured by shin-Etsu chemical industries, Ltd.)
(10) Radically curable resin
Each resin shown below was diluted with toluene, and the procedure of washing with ultrapure water was repeated to prepare a high-purity radical-curable resin. The radical-curable resin 2 described below was synthesized by the method of synthesis example II-1 described below.
Radical-curable resin 1: bisphenol A epoxy resin-modified diacrylate (3002A, molecular weight 600, chemical Co., Ltd.)
Radical-curable resin 2: (meth) acrylic acid-modified epoxy resin having epoxy group and (meth) acryloyl group in 1 molecule
[ Synthesis example II-1]
160g of bisphenol F type epoxy resin (EPOTATE YDF-8170C, manufactured by Tokyo chemical Co., Ltd.), 36g of acrylic acid and 0.2g of triethanolamine were charged into a 500ml four-necked flask equipped with a stirrer, a gas inlet, a thermometer and a condenser, and heated and stirred at 110 ℃ for 5 hours under a dry air flow to obtain an acrylic acid-modified epoxy resin. The obtained resin was washed with ultrapure water 12 times.
(11) Radical chain transfer agent
Radical chain transfer agent 1: 1, 3, 5-tris (3-mercaptobutyloxyethyl) -1, 3, 5-triazine-2, 4, 6(1H, 3H, 5H) -trione (Karenz MT NR-1: manufactured by Showa Denko K.K.)
Radical chain transfer agent 2: tetraethylthiuram disulfide (manufactured by Wako pure chemical industries)
Radical chain transfer agent 3: diethoxymethane polysulfide polymer (Thiokol LP-2: manufactured by Tooli Fine chemical Co., Ltd.)
Radical chain transfer agent 4: tert-dodecyl mercaptan
[ evaluation method ]
The evaluation methods performed in examples II-1 to 6 and comparative examples II-1 and II-2 will be described. Here, i) the display property of the liquid crystal display panel, ii) the sealing property of the liquid crystal sealant, and iii) the adhesive strength of the liquid crystal sealant after curing were measured, and the properties of the liquid crystal sealant were evaluated. Details of each measurement and evaluation method are as follows.
i) Display property of liquid crystal display panel
A35 mm × 40mm frame shape was drawn with a line width of 0.5mm and a thickness of 50 μm on a 40mm × 45mm glass substrate (RT-DM88 PIN: manufactured by EHC) with a transparent electrode and an alignment film, using a liquid crystal sealant containing 1% of 5 μm glass fibers. A dispenser (SHOTMASTER: manufactured by Wucang high-tech Co., Ltd.) is used for the drawing.
Next, a liquid crystal material (MLC-6848-. Next, 2 glass substrates were stacked in an opposed manner under a reduced pressure of 90Pa, fixed by applying a load, and further, both substrates were bonded by returning to atmospheric pressure from the reduced pressure. Subsequently, the bonded substrates were put into a circulating oven, heated at 70 ℃ for 30 minutes, and then further heated at 120 ℃ for 60 minutes to cure the liquid crystal sealing agent.
Polarizing films were attached to both surfaces of the 2 substrates to form a liquid crystal display panel. The liquid crystal display panel is driven by applying a voltage of 5V to the liquid crystal display panel by a dc power supply device. At this time, whether the liquid crystal display function in the vicinity of the seal tape formed of the liquid crystal sealing agent normally functions from the initial stage of driving was visually observed, and the display performance of the liquid crystal display panel was evaluated based on the following criteria.
Until the sealing strip all plays the condition of showing the function: o (good display)
No display function is performed up to a position deviated from the vicinity of the weather strip by more than 0.3 mm: x (remarkably poor in display)
ii) sealing property of liquid crystal sealing agent
3 liquid crystal display panels were produced in the same manner as the above-described liquid crystal display panel production method, and the sealing properties of the frame (seal bar) serving as the display region in each liquid crystal display panel were evaluated at 4 levels by the following criteria.
The case where the main seal is not broken and does not intrude into the seal line from the liquid crystal (hereinafter referred to as insertion): very good
See the inserted but not broken primary seal: o-
1 primary seal strip rupture case: delta
2 case of rupture of the above primary seal: is prepared from
iii) adhesive strength of cured liquid crystal sealing agent
First, a liquid crystal sealing agent containing 1% of 5 μm glass fibers was screen-printed on alkali-free glass 25 mm. times.45 mm. times.5 mm in thickness in a circular shape having a diameter of 1mm, and a pair of the same glasses was cross-pasted. Subsequently, the 2 adhered substrates were placed in a circulating oven while being held between clamps and loaded, and then heated at 70 ℃ for 30 minutes and further at 120 ℃ for 60 minutes to cure the liquid crystal sealing agent. Subsequently, a deflection film was attached to each of both surfaces of 2 substrates, and then the substrates were heated at 120 ℃ for 60 minutes in a nitrogen atmosphere to prepare test pieces in which the liquid crystal sealing agent was cured only by heating.
The obtained test piece was peeled off in a direction parallel to the bottom surface of the glass at a tensile speed of 2mm/min using a tensile tester (model 210: manufactured by Institox corporation), and the in-plane tensile strength was measured.
The adhesive strength was evaluated according to the following criteria.
Tensile strength of 10MPa or more: o (good adhesion)
Case where the tensile strength is less than 10 MPa: x (poor adhesion)
iv) viscosity stability of liquid Crystal sealant
The viscosity stability of the liquid crystal sealing agent prepared by the method described below was measured with an E-type rotary viscometer (model DII-III ULTRA, manufactured by Boehringer corporation). At this time, the viscosity of the liquid crystal sealing agent immediately after the preparation and the viscosity after 5 days of storage at 25 ℃ were measured. In the measurement, a CP-52 type conical plate sensor having a radius of 12mm and an angle of 3 ℃ was used, and the number of revolutions was set to 2.5 rpm.
Of the measured viscosities of the liquid crystal sealing agents, the viscosity immediately after the preparation was η 1, and the viscosity after 5 days of storage at 25 ℃ was η 2, and the viscosity stability of the liquid crystal sealing agent was evaluated by the following criteria.
Case where the value of η 2/η 1 is less than 1.5: o-
A value of η 2/η 1 of 1.5 or more and less than 2.0: delta
A value of η 2/η 1 of 2.0 or more: is prepared from
[ example II-1]
15 parts of the epoxy resin and 45 parts of the radical curable resin 1 were dissolved by heating at 100 ℃ for 1 hour to form a uniform solution. Then, after cooling the solution, 20 parts of the radical curable resin 2 obtained in Synthesis example II-1, 0.5 part of the radical chain transfer agent 1, 15 parts of the filler, 3 parts of the latent epoxy curing agent and 1 part of the silane coupling agent as an additive were added, and the mixture was premixed by a mixer and kneaded by a three-roll mill until the solid material became 5 μm or less. Subsequently, the mixture was filtered through a filter having a pore diameter of 10 μm (MSP-10-E10S: manufactured by ADVANTEC Co., Ltd.), 0.5 part of a thermal radical polymerization initiator was added thereto, and the mixture was subjected to vacuum agitation and defoaming treatment with a planetary mixer to prepare a liquid crystal sealing agent.
[ example II-2]
A liquid crystal sealing agent was prepared in the same manner as in example II-1 except that the radical chain transfer agent 2 was used.
[ example II-3]
A liquid crystal sealing agent was prepared in the same manner as in example II-1 except that the radical chain transfer agent 3 was used.
[ example II-4]
A liquid crystal sealing agent was prepared in the same manner as in example II-1 except that the amounts of the radical-curable resin 1, the radical-curable resin 2, the radical chain transfer agent 1 and the filler were 42.5 parts, 15 parts, 2.5 parts and 20.5 parts, respectively.
[ example II-5]
A liquid crystal sealing agent was prepared in the same manner as in example II-1 except that 48 parts of the radical-curable resin 1, 15 parts of the radical-curable resin 2, 22 parts of the filler, and 10 parts of the epoxy resin were used.
[ examples II-6]
A liquid crystal sealing agent was prepared in the same manner as in example II-1 except that the amount of the radical chain transfer agent 4 was changed to 0.5 part.
Comparative example II-1
A liquid crystal sealing agent was prepared in the same manner as in example II-1 except that the radical chain transfer agent was not used at all, and 45.5 parts of the radical-curable resin 1 and 20 parts of the radical-curable resin 2 were used.
Comparative example II-2
A liquid crystal sealing agent was prepared in the same manner as in example II-1 except that the amount of the radical curable resin 1 was changed to 45.5 parts without using a thermal radical polymerization initiator.
The amounts of the components of the liquid crystal sealing agents used in the examples and comparative examples, and the evaluation results on the sealing properties and adhesive strength of the prepared liquid crystal sealing agents and the display properties of the liquid crystal display panels using the liquid crystal sealing agents are summarized in table 4.
TABLE 4
As shown in Table 4, the liquid crystal sealing agents of examples II-1 to 6 to which the present invention was applied were confirmed to be excellent in the above-mentioned sealing property, adhesive strength and display property. On the other hand, in the case where no radical chain transfer agent was used, as shown in the results of comparative example II-1, it was found that the sealing property was poor although the display property was slightly inferior to that of the examples. Further, it was confirmed that when a thiol-based material is used as the heat curing agent, the viscosity stability of the liquid crystal sealing agent can be improved when a secondary thiol is used as compared with a primary thiol. On the other hand, in the case where the thermal radical polymerization initiator is not used, as shown in the result of comparative example II-2, it is clear that the sealing property, the adhesive strength and the display property are all significantly problematic.
Examples III-1 to 6 and comparative examples III-1 to 4
The following will describe examples and comparative examples carried out with respect to the curable resin composition III for liquid crystal sealing of the present invention.
[ preparations of materials used in examples III-1 to 6 and comparative examples III-1 to 4]
The materials used in the examples and the like are as follows.
(3) Thermal radical polymerization initiator
Thermal radical polymerization initiator 1: 2, 2' -azobis (2, 4-dimethylvaleronitrile) (V-65: manufactured with Wako pure chemical industries, 10-hour half-life temperature 51 ℃, heat release initiation temperature 51 ℃)
Thermal radical polymerization initiator 2: dimethyl-2, 2' -azobis (2-methylpropionate) (V-601 manufactured by Wako pure chemical industries, 10-hour half-life temperature 66 ℃ C., exothermic initiation temperature 60 ℃ C.)
Thermal radical polymerization initiator 3: tert-amyl peroxy-2-ethylhexanoate (Lupasol 575: produced by API Co., Ltd., 10-hour half-life temperature 75 ℃ C., exotherm onset temperature 88 ℃ C.)
Thermal radical polymerization initiator 4: 1, 1-azobis (2, 4-cyclohexane-1-carbonitrile) (PERHEXYL O manufactured by NOF corporation, 10-hour half-life temperature 70 ℃ C., exotherm starting temperature 105 ℃ C.)
(4) Filler material
Packing 1: spherical silica (Xifosta S-30: produced by Japan catalyst, average primary particle diameter0.3 μm, specific surface area 11m2/g)
And (3) filler 2: spherical silica (SO-C2: manufactured by Admatechs Co., Ltd., average primary particle diameter 0.9 μm, specific surface area 4m2/g)
And (3) filler: spherical silica (SO-C1: manufactured by Admatechs Co., Ltd., average primary particle diameter of 0.25 μm, specific surface area of 17.4m2/g)
And (4) filler: talc (SG-2000: manufactured by Nippon talc Co., Ltd., average primary particle diameter 1.0 μm, specific surface area 36.6m2/g)
(5) Epoxy curing agent
Latent epoxy curing agent 1: 1, 3-bis (hydrazinocarbonylethyl) -5-isopropylhydantoin (AmicureVDH: Melonin Co., Ltd., melting point 120 ℃ C.)
Latent epoxy curing agent 2: adipic acid dihydrazide (ADH: melting point 181 ℃ C., manufactured by Otsuka chemical Co.)
Latent epoxy curing agent 3: amicure PN-23J (melting point 105 ℃ C., manufactured by Ajinomoto Co.)
(7) Photo-radical polymerization initiator
Photo radical polymerization initiator 1: 2, 2-dimethoxy-2-phenylacetophenone (Irgacure 651: manufactured by Ciba specialty Chemicals Co., Ltd.)
(8) Thermoplastic polymers
Alkyl methacrylate copolymer Fine particles (F-325: 0.5 μm average primary particle diameter manufactured by ZEON Co., Ltd., Japan)
(9) Other additives
Coupling agent 1: silane coupling agent (S-510: manufactured by Chilean corporation)
Coupling agent 2: silane coupling agent (KBM-403: manufactured by shin-Etsu chemical Co., Ltd.)
(12) Curable resin
The resin (1A), the resin (1B) and the resin (1C) described below are preferably selected and used.
(1A) Resin (radical bifunctional resin)
Resin (A-1): resin synthesized by Synthesis example III-1 described below
Resin (A-2): resin synthesized by Synthesis example III-2
Resin (A-3): resin synthesized by Synthesis example III-3 described below
Resin (A-4): resin synthesized by Synthesis example III-4 described below
Resin (A-5): resin synthesized by Synthesis examples III-5 described below
Resin (A-6): bisphenol A type epoxy diacrylate
Resin (A-7): resin synthesized by Synthesis examples III-6 described below
(1B) Of (2) a resin
Resin (B-1): diphenyl ether type partially acrylated epoxy resin synthesized by synthetic examples III-7 described below
Resin (B-2): bisphenol F type partially acrylated epoxy resin synthesized by Synthesis examples III-8 described below
Resin (B-3): resorcinol diglycidyl ether type partially acrylated epoxy resin synthesized by Synthesis examples III-9 described below
Resin (B-4): resins synthesized by Synthesis examples III to 10 described below
Resin (B-5): resins synthesized by Synthesis examples III-11 described below
Resin (B-6): resins synthesized by Synthesis examples III-12 described below
(1C) Of (2) a resin
Resin (C-1): o-cresol novolac type solid epoxy resin (commercially available)
Resin (C-2): bisphenol A type epoxy resin (commercial product)
Resin (C-3) (for comparison): bisphenol A type epoxy resin (commercial product)
[ method of analyzing resin ]
In order to ascertain the quality and the like of the resin synthesized in each synthesis example, the measurement of the epoxy equivalent and the measurement of the acid value were appropriately carried out by the following methods.
1) Determination of epoxy equivalent
The epoxy equivalent is calculated by the following method: after dissolving the resin in a hydrochloric acid-dioxane solution, the amount of hydrochloric acid consumed by the epoxy group was titrated.
2) Acid value measurement
The acid value was measured as follows. First, a resin solution was prepared by dissolving a resin in a diethyl ether/ethanol solution. To the resin solution was added phenolphthalein ethanol solution. Subsequently, 0.1N KOH having alcoholic property was added dropwise to the resin solution, and the acid value was calculated from the amount of KOH consumed until the solution became colorless.
[ Synthesis example III-1]
Synthesis of the radical bifunctional resin (A-1)
A flask equipped with a thermometer, a condenser and a stirrer was prepared. 170g of bisphenol F diglycidyl ether (EPICLON 830S, epoxy equivalent 170g/eq, manufactured by Dainippon ink chemical Co., Ltd.), 79g of acrylic acid, 500g of toluene, and 0.1g of tert-butylammonium bromide were added to the flask, and stirred to form a uniform solution.
The solution was stirred at 90 ℃ for 2 hours, and then stirred under reflux for 36 hours to effect a reaction. Subsequently, the reaction solution was washed with ultrapure water, and toluene was removed to obtain a resin. The obtained resin had a number average molecular weight of 457 by GPC, and the peak thereof was a single peak. The obtained resin has 2 hydroxyl groups in the molecule, thereby having hydrogen bonding propertyThe amount of functional groups was calculated to be 4.38X 10-3mol/g. The structure of the resin obtained in this example is as follows.
[ solution 10]
[ Synthesis example III-2]
Synthesis of the radical bifunctional resin (A-2)
A flask equipped with a thermometer, a condenser and a stirrer was prepared. To the flask were added EPICLON850CRP (bisphenol A type epoxy resin: manufactured by Dainippon ink chemical industries), 200g, 100g of methacrylic acid, 900g of toluene, 0.4g of triethylamine, and 0.4g of p-methoxyphenol, and mixed. The mixture was stirred at 90 ℃ for 8 hours to allow reaction. After the reaction was completed, the reaction mixture was washed with ultrapure water and column-purified to obtain a resin in which 100% of the epoxy groups were methacrylated.
The obtained resin had a number average molecular weight of 513 as measured by GPC, and the peak thereof was a single peak. The obtained resin had 2 hydroxyl groups in the molecule, and the amount of the hydrogen-bonding functional group was calculated to be 3.90X 10-3mol/g. The structure of the resin obtained in this example is as follows.
[ solution 11]
[ Synthesis example III-3]
Synthesis of the radical bifunctional resin (A-3)
A flask equipped with a thermometer, a condenser and a stirrer was prepared. To the flask, 117g of resorcin diglycidyl ether (Denacol EX-201, epoxy equivalent 117eq/g, manufactured by chanchenoderma Kogyo Co., Ltd.), 79g of acrylic acid, 500g of toluene, and 1g of ammonium t-butyl bromide were added and stirred to form a uniform solution. The solution was stirred at 90 ℃ for 2 hours, and then further stirred under reflux for 6 hours to allow reaction.
Subsequently, the reaction solution was washed with ultrapure water, and toluene was removed to obtain a resin. The obtained resin had a number average molecular weight of 366 as measured by GPC, and the peak thereof was a single peak. The obtained resin had 2 hydroxyl groups in the molecule, and the amount of the hydrogen-bonding functional group was calculated to be 5.46X 10-3mol/g. The structure of the resin obtained in this example is as follows.
[ solution 12]
Synthesis examples III-4
Synthesis of the radical bifunctional resin (A-4)
A flask equipped with a thermometer, a condenser and a stirrer was prepared. 100g of diphenyl ether type epoxy resin (YSLV-80 DE, melting point 84 ℃ C., manufactured by Nippon iron chemical Co., Ltd.), 0.2g of p-methoxyphenol as a polymerization inhibitor, 0.2g of triethylamine as a reaction catalyst, 40g of acrylic acid and 500g of toluene were charged into the flask, and stirred to form a uniform solution. Then, the solution was reacted at 80 ℃ for 2 hours while feeding air into the flask, and further stirred for 36 hours while refluxing to effect a reaction.
Subsequently, the reaction mixture was washed with water with ultrapure water, and toluene was removed to obtain a resin having an epoxy group acrylated at 100%. The obtained resin had a number average molecular weight of 459 and a single peak, as measured by GPC. The obtained resin had 2 hydroxyl groups in the molecule, and the amount of the hydrogen-bonding functional group was calculated to be 4.36X 10-3mol/g. The structure of the resin obtained in this example is as follows.
[ solution 13]
[ Synthesis examples III-5]
Synthesis of the radical bifunctional resin (A-5)
A flask equipped with a thermometer, a condenser and a stirrer was prepared. 296.2g (2mol) of phthalic anhydride, 917.0g (2mol) of a 6-caprolactone adduct of 2-hydroxyethyl acrylate (Placcel FA3, molecular weight: 459g/mol, manufactured by Dailuo chemical Co., Ltd.), 4g of triethylamine and 0.9g of hydroquinone were added to the flask and mixed. The reaction mixture was stirred at 110 ℃ to allow it to react. The reaction was carried out while monitoring the acid value of the reaction mixture, and the reaction temperature was adjusted to 90 ℃ when the acid value of the reaction mixture became 48 mgKOH/g. Then, 680.82g (2mol) of bisphenol A diglycidyl ether and 1.6g of tetrabutylammonium bromide were added to the reaction mixture, and the mixture was reacted at 90 ℃ until the acid value of the reaction mixture became 2 mgKOH/g.
Subsequently, 144.1g (2mol) of acrylic acid and 1.8g of hydroquinone were further added to the reaction mixture, and the reaction was continued at 80 ℃ for 2 hours while feeding air into the flask, and further the temperature was raised to 90 ℃. The reaction was carried out until the acid value of the reaction mixture became 2 mgKOH/g.
The resin was obtained by subjecting the mixture after the completion of the reaction to ultrapure water washing and column purification. The resin is obtained by reacting one glycidyl group of bisphenol A diglycidyl ether with a carboxyl group of a compound obtained by reacting a 6-caprolactone adduct of 2-hydroxyethyl acrylate with phthalic anhydride, and reacting the other glycidyl group of bisphenol A diglycidyl ether with a carboxyl group of acrylic acid. The resin obtained in this example showed a single peak and a molecular weight of 1005 by GPC. The obtained resin had 2 hydroxyl groups in the molecule, and the amount of the hydrogen-bonding functional group was calculated to be 1.99X 10-3mol/g 。
Radical bifunctional resin (A-6)
Bisphenol A type epoxy diacrylate (EB 3700: manufactured by DAICEL-CYTEC Co., Ltd.) was used. The amount of the hydrogen-bonding functional group was 4.12X 10-3mol/g。
[ Synthesis examples III-6]
Synthesis of the radical bifunctional resin (A-7)
A flask equipped with a thermometer, a condenser and a stirrer was prepared. 172g of hexamethylene diisocyanate (manufactured by Kanto chemical Co., Ltd.) and 148g of glycidol (manufactured by Wako pure chemical industries, Ltd.) were added to the flask, and the mixture was stirred at 80 ℃ for 1 hour to mix. Subsequently, 0.05g of dibutyltin dilaurate was added to the reaction mixture, and the mixture was stirred at 80 ℃ for 2 hours to react. Further, 144g of acrylic acid was added to the reaction mixture, and the mixture was stirred at 90 ℃ for 12 hours to effect a reaction. Infrared spectroscopic analysis of the reaction mixture was performed to confirm that the absorption based on isocyanate disappeared.
Subsequently, the reaction mixture was subjected to ultrapure water washing and column refining to obtain 100% acrylate of hexamethylene diglycidyl diisocyanate. The resin obtained in this example showed a single peak and a molecular weight of 460 by GPC. The obtained resin had 2 hydroxyl groups in the molecule and 2 urethane bonding groups, so that the amount of the hydrogen-bonding functional group was calculated to be 8.70X 10-3mol/g。
(1B) Of (2) a resin
Synthesis examples III-7
Resin (B-1): synthesis of diphenyl ether type partially acrylated epoxy resin
A flask equipped with a thermometer, a condenser and a stirrer was prepared. 100g of diphenyl ether type epoxy resin (YSLV-80 DE, manufactured by Nippon iron chemical Co., Ltd., melting point 84 ℃ C.), 0.2g of p-methoxyphenol as a polymerization inhibitor, 20g of acrylic acid, 500g of toluene and 0.2g of triethylamine as a reaction catalyst were charged into the flask, and stirred to form a uniform solution. Then, the solution was stirred at 80 ℃ for 2 hours while feeding air into the flask, and further stirred for 24 hours while refluxing to allow the reaction.
After the reaction was completed, the reaction mixture was column-purified, and then washed with ultrapure water to further remove toluene, thereby obtaining a partially acrylated epoxy resin having 50% acrylated epoxy groups. The obtained resin had a number average molecular weight of 386 measured by GPC, and its peak was a single peak. The obtained resin had 1 hydroxyl group in the molecule, and the amount of the hydrogen-bonding functional group was calculated to be 2.59X 10-3mol/g. In addition, the resin had 1 epoxy group in the molecule, so that the amount of the epoxy group was calculated to be 2.59 × 10-3mol/g。
Synthesis examples III to 8
Resin (B-2): synthesis of bisphenol F type partially acrylated epoxy resin
A flask equipped with a thermometer, a condenser and a stirrer was prepared. 160g of bisphenol F type epoxy resin (EPOTATE YDF-8170C: manufactured by Tokyo chemical Co., Ltd.), 36g of acrylic acid and 0.2g of triethanolamine were charged into the flask and stirred. Subsequently, the mixture was stirred at 110 ℃ for 5 hours while blowing dry air into the flask, and the mixture was reacted to obtain an acrylic-modified epoxy resin. The obtained resin was column-purified and dissolved in toluene in the same amount as the resin.
After the toluene solution of the resin was washed with water using ultrapure water, toluene was further removed to obtain a partially acrylated epoxy resin having 50% acrylated epoxy groups. The obtained resin had a number average molecular weight of 384 as measured by GPC, and the peak thereof was a single peak. The obtained resin had 1 hydroxyl group in the molecule, and the amount of the hydrogen-bonding functional group was calculated to be 2.60X 10-3mol/g. In addition, the resin had 1 epoxy group in the molecule, so that the amount of the epoxy group was calculated to be 2.60 × 10-3mol/g。
Synthesis examples III-9
Resin (B-3): synthesis of resorcinol diglycidyl ether type partially acrylated epoxy resin
A flask equipped with a thermometer, a condenser and a stirrer was prepared. To the flask, 234g of resorcin diglycidyl ether (Denacol EX-201, epoxy equivalent 117eq/g, manufactured by Kasei Kogyo Co., Ltd.), 72g of acrylic acid, 500g of toluene, and 1g of ammonium t-butyl bromide were added and stirred to form a uniform solution. The solution was reacted at 90 ℃ for 2 hours, and further stirred under reflux for 6 hours to effect a reaction.
After the reaction was completed, the reaction mixture was subjected to column purification and ultrapure water washing to obtain a partially acrylated epoxy resin having an epoxy group acrylated by 50%. The obtained resin had a number average molecular weight of 294 as measured by GPC, and its peak was a single peak. The obtained resin had 1 hydroxyl group in the molecule, and the amount of the hydrogen-bonding functional group was calculated to be 3.40X 10-3mol/g. The obtained resin had 1 epoxy group in the molecule, so that the amount of the epoxy group was calculated to be 3.40X 10-3mol/g。
Synthesis examples III to 10
Synthesis of resin (B-4)
A flask equipped with a thermometer, a condenser and a stirrer was prepared. To the flask were added 296.2g (2mol) of phthalic anhydride, 1372.0g (2mol) of a 6-caprolactone adduct of 2-hydroxyethyl acrylate (Placcel FA5, molecular weight: 686g/mol, manufactured by Dailuo chemical Co., Ltd.), 4g of triethylamine and 0.9g of hydroquinone. The mixture was stirred at 110 ℃ to react. The reaction was carried out while monitoring the acid value, and the reaction temperature was adjusted to 90 ℃ when the acid value became 36 mgKOH/g.
Then, 680.82g (2mol) of bisphenol A diglycidyl ether and 1.6g of tetrabutylammonium bromide were added, and heating and stirring were continued until the acid value of the reaction mixture was 2 mgKOH/g.
After the reaction, the reaction mixture was washed with ultrapure water and column-purified to obtain a resin obtained by reacting a compound obtained by reacting 6-caprolactone adduct of 2-hydroxyethyl acrylate with phthalic anhydride with bisphenol A diglycidyl ether. The resin was analyzed by GPC, and the peak was a single peak having a number average molecular weightIs 1160. The obtained resin had 1 hydroxyl group in the molecule, and the amount of the hydrogen-bonding functional group was calculated to be 8.6X 10-4mol/g. The obtained resin had 1 epoxy group in the molecule, so that the amount of the epoxy group was calculated to be 8.6X 10-4mol/g。
Synthesis examples III-11
Synthesis of resin (B-5)
A flask equipped with a thermometer, a condenser and a stirrer was prepared. 190g of phenol novolac epoxy resin N-770 (manufactured by Dainippon ink) and 500ml of toluene were added to the flask, and stirred, and 0.1g of triphenylphosphine was further added thereto to prepare a uniform solution. This solution was brought to reflux, and 35g of acrylic acid was added dropwise over 2 hours while stirring. Subsequently, the reaction was stirred under reflux for 6 hours.
After the reaction, the reaction mixture was subjected to column purification and ultrapure water washing to obtain a resin. The resin was measured by GPC, and the peak was a single peak and the number average molecular weight was 1177. The epoxy equivalent of the obtained resin was measured, and it was confirmed that 50% of the epoxy groups were modified with acrylic acid. The obtained resin had 3 hydroxyl groups in the molecule, and the amount of the hydrogen-binding functional group was calculated to be 2.55X 10-3mol/g. The obtained resin had 3 epoxy groups in the molecule, so that the amount of the epoxy groups was calculated to be 2.55X 10-3mol/g。
Synthesis examples III-12
Synthesis of resin (B-6)
A flask equipped with a thermometer, a condenser and a stirrer was prepared. 172g of hexamethylene diisocyanate (manufactured by Kanto chemical Co., Ltd.) and 148g of glycidol (manufactured by Wako pure chemical industries, Ltd.) were added to the flask, and the mixture was stirred at 80 ℃ for 1 hour to react. Subsequently, 0.05g of dibutyltin dilaurate was added to the reaction mixture, and the mixture was stirred at 80 ℃ for 2 hours. Further, 72g of acrylic acid was added to the reaction mixture, and the mixture was stirred at 100 ℃ for 3 hours to mix.
After the reaction is finished, carrying out the reactionInfrared spectroscopic analysis of the mixture confirmed the disappearance of the isocyanate-based absorption. Next, the reaction mixture was washed with ultrapure water and column-purified to obtain hexamethylene diisocyanate and 50% acrylate of glycidyl ether reactant. The resin was measured by GPC, and the peak was a single peak and the number average molecular weight was 388. The obtained resin had 2 urethane-binding groups in the molecule and 1 hydroxyl group, so that the amount of the hydrogen-binding functional group was calculated to be 7.73X 10-3mol/g. The obtained resin had 1 epoxy group in the molecule, so that the amount of the epoxy group was calculated to be 2.58X 10-3mol/g。
(1C) Of (2) a resin
Resin (C-1): o-cresol novolac type solid epoxy resin (EOCN-1020: 75 ℃ C. softening point and 215g/eq epoxy equivalent by ring and ball method, manufactured by Nippon chemical Co., Ltd.)
The epoxy equivalent of the resin was 215g/eq, so that the molecular weight of the resin (C-1) per 1 epoxy group was 215. Thus, the epoxy group amount of the resin was calculated to be 4.65X 10-3mol/g. Since this resin does not contain a hydrogen-bonding functional group, the amount of the hydrogen-bonding functional group is 0. The weight average molecular weight of the resin was measured by GPC, and the result was 1075.
Resin (C-2): bisphenol A type epoxy resin (manufactured by EPIKOTE 1003: JER, softening point of 89 ℃ by ring and ball method, epoxy equivalent of 720g/eq)
The resin contained 2 epoxy groups in the molecule, so that the molecular weight of the resin was calculated as 1440. The epoxy group content of the resin was calculated to be 1.39X 10-3mol/g. The resin had almost no molecular weight distribution, and thus the weight average molecular weight was also 1440. The resin is represented by the following structural formula, and each repeating unit (molecular weight 284.4) has 1 hydroxyl group. The molecular weight of the resin was 1440, so that n was calculated to be 3.87. Thus, there were 3.87 hydroxyl groups on average per 1 molecule, and the amount of the hydrogen-binding functional group was calculated to be 2.69X 10-3mol/g。
[ solution 14]
The numbers in the above formulae indicate the molecular weights.
Epoxy resin (C-3) (for comparison): bisphenol A type epoxy resin (EPIKOTE 828 EL: JER, epoxy equivalent 190g/eq)
The resin (C-3) contained 2 epoxy groups in the molecule, so that the molecular weight of the resin was calculated as 380. Thus, the epoxy group amount of the resin was calculated to be 5.26X 10-3mol/g. This resin also has a structure represented by formula (2), and n is calculated to be 0.14. Thus, since it has 0.14 hydroxyl groups, the amount of the hydrogen-binding functional group was calculated to be 3.7X 10-4mol/g. The resin is liquid at room temperature and thus has a softening point of less than 40 ℃.
[ evaluation method ]
The evaluation methods performed in examples III-1 to 6 and comparative examples III-1 to 4 will be described. Here, i) the leakage resistance of the liquid crystal sealing agent, ii) the coating property of the liquid crystal sealing agent, iii) the seal appearance and the adhesive strength, and iv) the viscosity of the liquid crystal sealing agent were measured, and the characteristics of the liquid crystal sealing agent were evaluated. Details of each evaluation measurement method are as follows.
i) Leakage resistance of liquid crystal sealing agent
To a liquid crystal sealing agent prepared by the method described later, 1 part of 4.8 μm spherical spacers was further added to prepare a spacer-added liquid crystal sealing agent. Next, a 40mm X45 mm glass substrate (RT-DM88 PIN: manufactured by EHC) having a transparent electrode and an alignment film was prepared. The composition was filled into a dispenser (manufactured by Hitachi Industrial devices and technologies Co., Ltd.), and a seal pattern of 35mm × 40mm square (cross-sectional area 3500 μm) was drawn on a glass substrate2)。
A dispenser (manufactured by Hitachi Industrial devices and technologies) was used to precisely drop a liquid crystal material (MLC-11900:000: Merck) in an amount corresponding to the inner volume of the panel after the attachment into the seal pattern of the substrate.
The glass substrate and the opposing glass substrate were stacked under a reduced pressure of 10Pa using a vacuum bonding apparatus (manufactured by shin & lten & gt engineering & ltSUB & gt). Then, the stacked glass substrates were sandwiched between 2 prepared glass substrates of 40mm × 45mm, and fixed by applying a load. The glass substrate used was a substrate having both surfaces subjected to a chromium sputtering treatment. Next, the stacked glass substrates were opened to the atmosphere and heated at 120 ℃ for 60 minutes to be cured (hereinafter referred to as "curing step in the leak resistance test").
The seal pattern linearity, i.e., the seal linearity of the liquid crystal display panel, which is an index of the leakage resistance, was evaluated by the following method.
[ ratio of maximum width to minimum width of weatherstrip ]% ([ minimum width of weatherstrip ]/[ maximum width of weatherstrip ] × 100%
The above ratio is 95% or more: very good (Excellent)
80% or more and less than 95%: o (slightly better)
Less than 80% of cases: x (poor)
ii) coatability of liquid crystal sealing agent
The liquid crystal sealant used in i) above was filled into a syringe under vacuum. Next, a syringe having a needle point with a diameter of 0.4mm was mounted in a dispenser (manufactured by hitachi industrial equipment and technology corporation), and 50 seal patterns of 35mm × 40mm were drawn on a glass substrate for a liquid crystal display panel (manufactured by japan electric glass company) of 300mm × 400mm using the syringe. At this time, the discharge pressure was set to 0.3MPa and the cross-sectional area was set to 3500 μm2The coating speed was 100 mm/sec.
The seal shape of the drawn seal pattern was evaluated by the following criteria.
The number of frame types which do not generate sealing interruption and sealing flash at all is 48-50: very good (Excellent)
The number of the frame shapes is more than 45 and less than 48: o (slightly better)
The number of the frame types is less than 44: x (poor)
iii) seal appearance and bond strength
The liquid crystal sealing agent prepared in 1) above was coated with a circular seal pattern having a diameter of 1mm on alkali-free glass having a thickness of 25mm × 45mm × 4mm using a screen printing plate. Subsequently, the alkali-free glass and a pair of the same glasses were fixed to each other in a crossed manner, and then the pair of fixed glasses was heated at 120 ℃ for 60 minutes to be bonded (hereinafter referred to as "curing step in adhesion test"). The obtained 2 glass plates (hereinafter referred to as "test pieces") were stored in a thermostatic bath at 25 ℃ and a humidity of 50% for 24 hours, and then the appearance of the seal was visually observed. The seal appearance is also a reference value for the liquid crystal contamination of the liquid crystal sealant.
The seal appearance was evaluated on the following criteria.
No voids and no bleeding were observed by visual inspection: very good (Excellent)
A few voids or bleeds were visually observed: delta (slightly good)
Visually, bleed and voids were found: x (poor)
Further, the planar tensile strength at a tensile rate of 2mm/min was measured with respect to the test piece taken out of the thermostatic bath using a tensile testing apparatus (manufactured by Institox).
The adhesive strength was evaluated according to the following criteria.
The bonding strength is more than 10 MPa: very good (Excellent)
The bonding strength is 7MPa or more and less than 10 MPa: o (slightly better)
The bonding strength is less than 7 MPa: x (poor)
iv) measurement of viscosity of liquid Crystal sealant
The viscosity of the composition was measured using an E-type rotary viscometer (manufactured by Boehringer corporation: digital rheometer, model DV-III ULTRA) and a CP-52 cone-plate type sensor having a radius of 12mm and an angle of 3 ℃ under the following conditions at a rotation speed of 1.0 rpm.
Viscosity at 25 ℃: the liquid crystal sealant of the present invention was left at 25 ℃ for 5 minutes and then measured.
Viscosity at 80 ℃: the liquid crystal sealing agent of the present invention was placed in a cup of an E-type rotational viscometer, heated to 80 ℃ at a heating rate of 5 ℃/min, and left at 80 ℃ for 5 minutes, and then measured.
In the above-mentioned measurement method, the viscosity of the liquid crystal sealing agent at 80 ℃ is not measured when it exceeds the measurement limit, and the measurement is carried out by the parallel plate method (RheoStress RS 150: manufactured by HAAKE). Measurement by the parallel plate method was carried out immediately after the temperature was raised to 80 ℃ at a temperature raising rate of 5 ℃ per minute according to the standard method of the above-mentioned model. The Thixotropic Index (TI) was measured at 25 ℃ at 0.5rpm and 5.0rpm using an E-type rotary viscometer (digital rheometer, model DV-III ULTRA: manufactured by Boleyfield) and a CP-52 cone-plate type sensor having a radius of 12mm and an angle of 3 ℃ and was expressed as a value of [ viscosity at 25 ℃ C. and 0.5rpm ]/[ viscosity at 25 ℃ C. and 5.0rpm ].
[ example III-1]
As the curable resin, 30 parts of resin (a-1), 30 parts of resin (a-3) and 30 parts of resin (a-5) were prepared, and 10 parts of epoxy resin 1, 20 parts of filler 1, 1 part of thermal radical polymerization initiator 1 and 8 parts of epoxy curing agent 1 were prepared. They are premixed with a mixer. Subsequently, the mixture was kneaded with a three-roll mill until the solid material became 4 μm or less. Subsequently, the kneaded mixture was filtered through a filter having a pore diameter of 10 μm (MSP-10-E10S: manufactured by ADVANTEC Co., Ltd.), and then subjected to vacuum defoaming treatment to obtain a liquid crystal sealing agent.
The amount of the hydrogen-bonding functional group in the curable resin contained in the liquid crystal sealing agent was 3.55X 10-3mol/g, epoxy group amount of 0.47X 10-3mol/g。
The viscosity at 25 ℃ of the thus obtained liquid crystal sealing agent was 440 pas at 0.5rpm, 350 pas at 1.0rpm, and 280 pas at 5 rpm.
The viscosity of the E-type rotary viscometer at 80 ℃ was measured by the parallel plate method (RheoStress RS 150: manufactured by HAAKE) because it exceeded 780 pas. As a result, 9.00E +05 pas was obtained. The thixotropic index was 1.6.
The liquid crystal sealing agent was evaluated by various tests.
[ examples III-2 to 6]
Each component shown in Table 5 described later was prepared, and a liquid crystal sealing agent was prepared in the same manner as in example III-1. The same evaluation as in example III-1 was carried out for each liquid crystal sealing agent.
Comparative example III-1
Each component shown in Table 6 described later was prepared, and a liquid crystal sealing agent was prepared in the same manner as in example III-1. The same evaluation as in example III-1 was carried out for each liquid crystal sealing agent. However, the "curing step in the evaluation of the leakage resistance" was carried out by irradiating 3000mJ of ultraviolet light before heating at 120 ℃ for 60 minutes. The "curing step in the adhesion test" was performed by irradiating 3000mJ of ultraviolet light even before heating at 120 ℃ for 60 minutes.
Comparative examples III-2 and 3
Each component shown in Table 6 described later was prepared, and a liquid crystal sealing agent was prepared in the same manner as in example III-1. The same evaluation as in example III-1 was carried out for each liquid crystal sealing agent.
Comparative examples III to 4
Each component shown in Table 6 described later was prepared, and a liquid crystal sealing agent was prepared in the same manner as in comparative example III-1. The same evaluation as in example III-1 was carried out for each liquid crystal sealing agent.
TABLE 5
TABLE 6
As is apparent from comparison of examples III-1 to 6 and comparative examples III-1 to 4, the liquid crystal sealing agent of the present invention containing a curable resin having a hydrogen bonding functional group amount and an epoxy group amount within specific ranges is excellent in leakage resistance, adhesiveness and coatability. In particular, as is apparent from comparison between each example and comparative example III-4, the liquid crystal sealing agent of the present invention containing an epoxy resin having a softening point and a molecular weight within specific ranges is superior in leakage resistance and adhesiveness to a liquid crystal sealing agent containing an epoxy resin having a softening point and a molecular weight outside these ranges.
Possibility of industrial utilization
The curable resin composition for sealing liquid crystals of the present invention can be cured quickly and sufficiently by heating without using light. Therefore, the liquid crystal sealing agent produced using the curable resin composition for liquid crystal sealing of the present invention has high curability and thus is excellent in leakage resistance, and liquid crystal contamination is suppressed, whereby it can be effectively used as a liquid crystal sealing agent capable of providing a liquid crystal display panel having good display characteristics.
The present application claims priority based on 1) application number JP2007-039938 applied on 2/20/2007, 2) application number JP2007-169749 applied on 27/6/2007, 3) application number JP2007-295925 applied on 14/11/2007. The contents described in these application specifications are incorporated herein in their entirety.

Claims (13)

1. A curable resin composition for sealing a liquid crystal,
comprises 100 parts by mass of an acrylic resin and/or a (meth) acrylic-modified epoxy resin having 1 or more epoxy groups and (meth) acryloyl groups in each molecule, 0.01 to 3.0 parts by mass of a thermal radical polymerization initiator, and 1 to 50 parts by mass of a filler,
the viscosity at 25 ℃ and 1.0rpm measured by an E-type viscometer is 50 to 500 pas, and the viscosity at 80 ℃ and 1.0rpm is more than 500 pas.
2. The curable resin composition for sealing liquid crystal according to claim 1,
the filler has an average primary particle diameter of 1.5A or less and a specific surface area of 1 to 500m2(ii) 1 to 50 parts by mass per 100 parts by mass of the total of the acrylic resin and the (meth) acrylic acid-modified epoxy resin,
the thixotropic index defined by [ viscosity at 25 ℃ and 0.5rpm measured by an E-type viscometer ]/[ viscosity at 25 ℃ and 5.0rpm measured by an E-type viscometer ] is 1.1 to 5.0.
3. The curable resin composition for sealing a liquid crystal according to claim 1, wherein the thermal radical polymerization initiator has a 10-hour half-life temperature defined as a temperature at which a concentration of the thermal radical polymerization initiator becomes half when a thermal decomposition reaction is carried out at a certain temperature for 10 hours, of 40 to 80 ℃.
4. A curable resin composition for sealing a liquid crystal,
comprises 100 parts by mass of a radical-curable resin having a carbon-carbon double bond capable of radical polymerization in 1 molecule, 0.01 to 5.0 parts by mass of a thermal radical polymerization initiator, 0.01 to 5.0 parts by mass of a radical chain transfer agent, and 1 to 30 parts by mass of a filler,
the viscosity at 25 ℃ and 1.0rpm measured by an E-type viscometer is 50 to 500 pas, and the viscosity at 80 ℃ and 1.0rpm is more than 500 pas.
5. The curable resin composition for sealing a liquid crystal according to claim 4, wherein the radical chain transfer agent is a thiol.
6. The curable resin composition for sealing a liquid crystal according to claim 4, wherein the thiol as the radical chain transfer agent is a secondary thiol having a number average molecular weight of 400 to 2000.
7. The curable resin composition for sealing liquid crystal according to claim 4, wherein the thermal radical polymerization initiator is an organic peroxide or an azo compound.
8. A curable resin composition for sealing a liquid crystal,
comprising 100 parts by mass of a resin composition containing a radically polymerizable carbon-carbon double bond, a hydrogen-bonding functional group, and an epoxy group; 0.01-5.0 parts by mass of a thermal radical polymerization initiator; and 1 to 30 parts by mass of a filler,
the resin composition comprises a mixture of (1A) a resin having a hydrogen-bonding functional group and a radically polymerizable 2-carbon double bond in 1 molecule, and the amount of the hydrogen-bonding functional group is 1.5X 10-3～6.0×10-3mol/g of a free radical reactive resin; (1B) has a hydrogen-bonding functional group, an epoxy group and a radically polymerizable carbon-carbon double bond in 1 molecule, and the amount of the hydrogen-bonding functional group is 1.0X 10- 4～5.0×10-3mol/g of a free radical reactive resin; and (1C) 2 or more resins selected from the group consisting of epoxy resins having an epoxy group in 1 molecule but no radically polymerizable carbon-carbon double bond, a softening point of 40 ℃ or higher as measured by the ring and ball method, and a weight average molecular weight of 500 to 5000,
the amount of the hydrogen-binding functional group in the resin composition is 1.0X 10-4～6.0×10-3mol/g，
The amount of epoxy groups in the resin composition was 1.0X 10-4～2.6×10-3mol/g，
The curable resin composition for sealing liquid crystal has a viscosity of 50 to 500 pas at 25 ℃ and 1.0rpm and a viscosity of more than 500 pas at 80 ℃ and 1.0rpm measured by an E-type viscometer
The hydrogen-binding functional group is at least one group selected from the group consisting of: a hydroxyl group; -NH2A group; -NHR group, wherein R represents an aliphatic hydrocarbon group or an aromatic group; -CONH2A group; -NH-group; -NHOH group; -NHCO-binding group, -CONHCO-binding group; or an-NH-NH-binding group.
9. The curable resin composition for sealing a liquid crystal according to claim 8, wherein the hydrogen-bonding functional group in the resin composition is a hydroxyl group.
10. The curable resin composition for sealing a liquid crystal according to claim 8, wherein the radical-reactive resin (1A) is a resin represented by the following general formula (a1) or general formula (a 2);
general formula (a 1):
r in the general formula (a1)1、R2、R3、R4Each independently represents a hydrogen atom or a methyl group, RmEach independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group, a hydroxyalkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, n represents an integer of 1 to 4, 1 represents an integer of 1 to 4, A represents a group represented by-CH2-、-C(CH3)2-、-SO2-or-O-represents an organic group;
general formula (a 2):
r in the general formula (a2)5、R6、R7、R8Each independently represents a hydrogen atom or a methyl group, RqEach independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group, a hydroxyalkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, r represents an integer of 1 to 4, and p represents an integer of 1 to 4.
11. The curable resin composition for sealing a liquid crystal according to claim 8, wherein the radical-reactive resin (1A) is a resin represented by the following general formula (a3) or general formula (a 4);
general formula (a 3):
r in the general formula (a3)1、R2Each independently represents a hydrogen atom or a methyl group, RmEach independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group, a hydroxyalkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, n represents an integer of 1 to 4, A represents a group represented by-CH2-、-C(CH3)2-、-SO2-or-O-represents an organic group;
general formula (a 4):
r in the general formula (a4)5、R6Each independently represents a hydrogen atom or a methyl group.
12. The curable resin composition for liquid crystal sealing according to claim 8, further comprising a radical chain transfer agent.
13. A method for manufacturing a liquid crystal display panel in which 2 substrates facing each other are bonded to each other with a curable resin composition for liquid crystal sealing, comprising:
preparing a1 st substrate including a frame-shaped display region in which a pixel array region is surrounded by the curable resin composition for sealing liquid crystal according to claim 1, 4, or 8;
dropping a liquid crystal into the display region in an uncured state or into another substrate;
a step of superposing the 1 st substrate and the 2 nd substrate opposed thereto;
and curing the liquid crystal sealing resin composition by heating.
HK10103219.7A 2007-02-20 2008-02-19 Curable resin composition for sealing liquid crystal, and method for production of liquid crystal display panel using the same HK1136357B (en)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
JP2007-039938 2007-02-20
JP2007039938 2007-02-20
JP2007-169749 2007-06-27
JP2007169749 2007-06-27
JP2007295925 2007-11-14
JP2007-295925 2007-11-14
PCT/JP2008/000273 WO2008102550A1 (en) 2007-02-20 2008-02-19 Curable resin composition for sealing liquid crystal, and method for production of liquid crystal display panel using the same

Publications (2)

Publication Number Publication Date
HK1136357A1 true HK1136357A1 (en) 2010-06-25
HK1136357B HK1136357B (en) 2013-02-08

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JP5060544B2 (en) 2012-10-31
CN101617267A (en) 2009-12-30
JPWO2008102550A1 (en) 2010-05-27
TW200900816A (en) 2009-01-01
TWI420205B (en) 2013-12-21
CN101617267B (en) 2012-08-15

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