JP5651073B2 - Adhesive, adhesive sheet and laminate for touch panel - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive used for a laminate for a touch panel, a pressure-sensitive adhesive sheet obtained by forming the pressure-sensitive adhesive into a sheet, and a laminate for a touch panel in which a member is attached using the pressure-sensitive adhesive sheet.

  At present, the touch panel units mainly used are roughly classified into a resistance film type touch panel and a capacitance type touch panel, both of which are laminates of various materials. System adhesive is used. Since the touch panel unit is disposed on the outermost surface of the screen, the acrylic pressure-sensitive adhesive to be used is required to have high transparency, and further, characteristics such as high heat resistance and moisture heat resistance are required. Specifically, since the touch panel unit, which is a laminate of various materials, is disposed on the outermost surface of the touch panel device, whitening may occur due to the ingress of moisture from the outside. Foaming by entraining and foaming by outgas generated from the material to be laminated are problematic in that appearance defects occur.

  Moreover, in the resistive film type touch panel which has been the mainstream of touch panels so far, various adhesives have been used for attaching polycarbonate (PC) or in-mold film (IMD).

  However, as a characteristic of the PC material, outgas is generated under a high temperature condition, so that foaming occurs under a heat resistant condition and it is difficult to suppress the whitening phenomenon of the pressure-sensitive adhesive layer due to moisture inflow under a wet heat condition. Furthermore, since the IMD has a step of submicron order, there is also a problem that the pressure-sensitive adhesive cannot follow the step and bubbles are involved.

  Conventionally, the above problems have been solved by adding an acid component to the pressure-sensitive adhesive. In other words, the acid component has the function of dispersing the mixed water and preventing it from being deposited, and the water that has entered the pressure-sensitive adhesive layer is dispersed and not precipitated in the pressure-sensitive adhesive layer by the dispersion force of the acid component. The pressure-sensitive adhesive layer was prevented from being whitened and also formed with hydrogen bonds, so the generation of bubbles in heat-resistant foaming was suppressed by the high cohesive force due to the hydrogen bonds.

  Recently, with the enhancement of functions such as multi-touch, capacitive touch panels are becoming the mainstream instead of resistive touch panels. In this capacitive touch panel, the characteristics required for the resistive touch panel are of course necessary, but in addition, because the adhesive is in direct contact with the conductive layer forming the wiring, The property that the adhesive does not change the properties of the conductive layer is required. The conductive layer is formed of a metal or metal oxide such as indium tin oxide (ITO), which causes corrosion due to contact with an acid and increases its resistance value. Means for securing properties such as heat resistance and wet heat resistance using components cannot be used.

  Regarding the corrosion of such transparent electrodes made of metals such as ITO or metal oxides, Patent Document 1 (Japanese Patent Laid-Open No. 2010-77287) discloses a polymer mainly composed of alkoxyalkyl acrylate. In this Patent Document 1, it is disclosed to use an alkoxyalkyl acrylate polymer having a weight average molecular weight of 400,000 to 1.6 million and not using a carboxyl group-containing monomer.

  Thus, by using 400,000 to 1.6 million alkoxyalkyl acrylate polymers without using carboxyl group-containing monomers, the corrosion of transparent electrodes made of metals such as ITO or metal oxides is improved to some extent. However, sufficient effects are not obtained with respect to performance such as wet heat whitening and heat resistant foaming. Furthermore, workability is not sufficient.

  Furthermore, since the weight average molecular weight of the polymer disclosed in Patent Document 1 is as large as 400,000 to 1.6 million, the viscosity of the polymer solution increases when the solid content increases when this is dissolved in a solvent to prepare a coating solution. Is too high. In touch panel applications, particularly capacitive touch panel applications, it is necessary to form a thick adhesive layer in order to adhere a surface support and a conductive film such as ITO, but the weight average molecular weight is 400,000 to Since a coating liquid with a high solid content cannot be prepared using 1.6 million alkoxyalkyl acrylate polymers, it is necessary to prepare a coating liquid with a low solid content and apply repeatedly. There is a problem that it is difficult to form an adhesive layer having a thickness required for coating.

JP 2010-77287 A

The present invention relates to a pressure-sensitive adhesive for a touch panel having a conductive film made of a metal or a metal oxide, having excellent heat resistance and heat-and-moisture stability, a non-corrosive pressure-sensitive adhesive to a metal or metal oxide, a pressure-sensitive adhesive sheet, and It aims at providing the laminated body for touchscreens using this.
Another object of the present invention is to provide a pressure-sensitive adhesive or pressure-sensitive adhesive sheet with good workability.

The pressure-sensitive adhesive of the present invention comprises the following components (a-1) and (a-2)
(A-1) Alkoxy (meth) acrylate 20 to 99.9% by weight
(A-2) Monomer having a crosslinkable functional group 0.1 to 10% by weight
A main acrylic polymer (A) having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which is substantially free of acidic groups obtained by copolymerizing a monomer containing styrene, and 100 parts by weight of the main acrylic polymer (A) Against
Low molecular weight (meth) acrylic polymer (B) having a hydrogen-bonding functional group and having substantially no acidic group and a weight average molecular weight of less than 100,000: 0.1 to 15 parts by weight;
Isocyanate crosslinking agent (C): 0.1 to 2 parts by weight is contained. However, the weight average molecular weight of the main acrylic polymer (A) in the pressure-sensitive adhesive and the weight average molecular weight of the low molecular weight (meth) acrylic polymer (B) have a relationship of A> B.

  The pressure-sensitive adhesive is preferably a pressure-sensitive adhesive for a capacitive touch panel that is in direct contact with a metal or metal oxide.

The pressure-sensitive adhesive sheet of the present invention comprises the following components (a-1) and (a-2)
(A-1) Alkoxy (meth) acrylate 20 to 99.9% by weight
(A-2) Monomer having a crosslinkable functional group 0.1 to 10% by weight
A main acrylic polymer (A) having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which is substantially free of acidic groups obtained by copolymerizing a monomer containing styrene, and 100 parts by weight of the main acrylic polymer (A) Against
Low molecular weight (meth) acrylic polymer (B) having a hydrogen-bonding functional group and having substantially no acidic group and a weight average molecular weight of less than 100,000: 0.1 to 15 parts by weight;
It is characterized by having a pressure-sensitive adhesive layer having a thickness in the range of 10 to 1000 μm formed from a pressure-sensitive adhesive containing isocyanate-based crosslinking agent (C): 0.1 to 2 parts by weight. However, the weight average molecular weight of the main acrylic polymer (A) in the pressure-sensitive adhesive and the weight average molecular weight of the low molecular weight (meth) acrylic polymer (B) have a relationship of A> B.

As for the adhesive sheet of this invention, it is preferable that the cover film which gave the peeling process is arrange | positioned on the at least one surface.
The pressure-sensitive adhesive or the pressure-sensitive adhesive forming the pressure-sensitive adhesive sheet is preferably a pressure-sensitive adhesive for a capacitive touch panel that is in direct contact with a metal or a metal oxide.

The laminate for a touch panel of the present invention includes the following components (a-1) and (a-2).
(A-1) Alkoxy (meth) acrylate 20 to 99.9% by weight
(A-2) Monomer having a crosslinkable functional group 0.1 to 10% by weight
A main acrylic polymer (A) having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which is substantially free of acidic groups obtained by copolymerizing a monomer containing styrene, and 100 parts by weight of the main acrylic polymer (A) Against
Low molecular weight (meth) acrylic polymer (B) having a hydrogen-bonding functional group and having substantially no acidic group and a weight average molecular weight of less than 100,000: 0.1 to 15 parts by weight;
Isocyanate-based crosslinking agent (C): a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive containing 0.1 to 2 parts by weight (within the pressure-sensitive adhesive) The weight average molecular weight of the main acrylic polymer (A) and the weight average molecular weight of the low molecular weight (meth) acrylic polymer (B) have a relationship of A> B.) A transparent conductive film made of metal, metal oxide, metal with electrode support or metal oxide is attached to the other surface of the pressure-sensitive adhesive sheet, with a frame printed surface support attached to the edge of the facing surface Is affixed.

The touch panel laminate is preferably a member forming a capacitive touch panel.
Moreover, the thickness of the said frame printing is in the range of 10-50 micrometers normally.
Furthermore, the transparent electrode film is a wiring pattern using ITO, ATO or tin oxide as a metal oxide, and is particularly useful for a touch panel laminate in which the adhesive sheet is in direct contact with the wiring pattern.
Here, the thickness of the surface support is usually in the range of 25 to 2000 μm, and the thickness of the transparent conductive film is usually in the range of 10 to 100 nm.

In the pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and touch panel laminate of the present invention, the monomer (a-2) having a crosslinkable functional group forming the main acrylic polymer (A) is preferably a hydroxyl group-containing monomer.
Furthermore, in the pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and touch panel laminate of the present invention, the hydrogen bonding functional group introduced into the low molecular weight (meth) acrylic polymer (B) is an amino group-containing monomer or an amide group-containing monomer. And a group introduced by copolymerizing at least one monomer selected from the group consisting of a monomer containing a nitrogen-based heterocyclic ring and a monomer containing a cyano group.

  In the pressure-sensitive adhesive, pressure-sensitive adhesive sheet and touch panel laminate of the present invention, the glass transition temperature (Tg-1) of the main acrylic polymer (A) is in the range of −70 ° C. to 0 ° C., and has a low molecular weight ( The glass transition temperature (Tg-2) of the (meth) acrylic polymer (B) is in the range of 50 ° C. to 110 ° C., and the glass transition temperature (Tg-2) of the low molecular weight (meth) acrylic polymer (B). ) And the glass transition temperature (Tg-1) of the main acrylic polymer (A) [(Tg-2)-(Tg-1)] is preferably 50 ° C or higher.

Since the pressure-sensitive adhesive of the present invention does not substantially contain an acid component, deterioration due to corrosion of a metal or metal oxide such as silver, ITO, ATO, or tin oxide can be effectively suppressed.
Furthermore, since the pressure-sensitive adhesive of the present invention has a weight average molecular weight (Mw) of 50,000 or more and less than 400,000, the solid content can be kept at a high concentration in the solvent, and a sufficient thickness can be obtained by a single coating process. Can be painted.

In addition, the main polymer is an acrylic polymer having a specific weight average molecular weight mainly composed of alkoxy (meth) acrylate, and by adding a low molecular weight polymer to this, the hydrogen bonding functional group in the low molecular weight polymer is reduced. Acts as a pseudo-crosslinking material.
And since a crosslinked structure is formed with an isocyanate type crosslinking agent, the adhesive of this invention is excellent in heat resistance and heat-and-moisture-resistant stability, and has very favorable level | step difference followability (step level followable | trackability).

  Therefore, the pressure-sensitive adhesive of the present invention, the pressure-sensitive adhesive sheet having this pressure-sensitive adhesive as a pressure-sensitive adhesive layer, and the touch panel laminate using this pressure-sensitive adhesive sheet are transparent conductive materials made of metals such as ITO, ATO, and tin oxide, or metal oxides. Corrosion with respect to the film hardly occurs, and the electrical characteristics of the transparent conductive film hardly change, and whitening and foaming hardly occur.

FIG. 1 is a cross-sectional view schematically showing an example of a touch panel unit in a resistive film type touch panel incorporating the laminate for a touch panel of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a touch panel unit in a capacitive touch panel incorporating the laminate for a touch panel of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of the configuration of the end of the capacitive touch panel. FIG. 4 is a cross-sectional view schematically showing the adhesive state of the adhesive sheet to the frame print portion formed at the end of the touch panel. FIG. 5 is a cross-sectional view for explaining the state of foaming that occurs in the laminate for a touch panel. FIG. 6 is a cross-sectional view for explaining the occurrence of a whitening phenomenon that occurs in the laminate for a touch panel.

Next, the pressure-sensitive adhesive, pressure-sensitive adhesive sheet and touch panel laminate of the present invention will be specifically described.
The pressure-sensitive adhesive of the present invention comprises a main acrylic polymer (A), a low molecular weight (meth) acrylic polymer (B), and an isocyanate crosslinking agent (C).

In the present invention, the main acrylic polymer (A) comprises the following components (a-1) and (a-2)
(A-1) alkoxy (meth) acrylate,
(A-2) A polymer obtained by copolymerizing a monomer having a crosslinkable functional group.

  Examples of the (a-1) alkoxy (meth) acrylate constituting the main acrylic polymer (A) used here include 2-methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2- Mention may be made of ethoxyethyl acrylate, methoxydiethylene glycol (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate. it can. Among these (a-1) alkoxyalkyl (meth) acrylates, 2-methoxyethyl (meth) acrylate and methoxydiethylene glycol (meth) acrylate are preferably used, and these can be used alone or in combination.

  In the main acrylic polymer of the present invention, the (a-1) alkoxy (meth) acrylate is 20 to 99.9% by weight, preferably 30 to 99.5% by weight, more preferably 50 to 98.8% by weight. Is copolymerized in the amount of (A-1) When the amount of the alkoxy (meth) acrylate is more than 99.5% by weight, the amount of the monomer having a crosslinkable functional group is inevitably reduced and a sufficient crosslinking density cannot be achieved. On the other hand, when it is less than 20% by weight, the whitening resistance of the pressure-sensitive adhesive of the present invention is lowered.

  The monomer (a-2) having a crosslinkable functional group that is copolymerized with the above (a-1) alkoxy (meth) acrylate to form a main monomer is a (meth) acrylate compound having a hydroxyl group as the crosslinkable functional group Examples of such (meth) acrylate compounds having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, Examples include 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl (meth) acrylate. As the (meth) acrylate compound having a hydroxyl group as described above, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable, and the (meth) acrylate compound having these hydroxyl groups may be used alone or Can be used in combination.

  In the main acrylic polymer (A) used in the present invention, (a-2) the monomer having a crosslinkable functional group is 0.1 to 10% by weight, preferably 0.5 to 9% by weight, more preferably Copolymerized in an amount in the range of 1.2 to 6% by weight.

  (A-2) If the amount of the monomer having a crosslinkable functional group is less than the above, a crosslinked structure by the isocyanate crosslinking agent may not be sufficiently formed, and if the monomer having a crosslinkable functional group is more than 10% by weight, The cross-linked structure becomes too dense, and the step following ability may deteriorate.

  Furthermore, the main acrylic polymer of the present invention is a range that does not impair the characteristics of the main acrylic polymer in addition to the (a-1) alkoxy (meth) acrylate and (a-2) monomer having a crosslinkable functional group. Other acrylic monomers may be copolymerized therein.

  Here, examples of other monomers forming the main acrylic polymer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl ( (Meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) Mention may be made of acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undeca (meth) acrylate and dideca (meth) acrylate. These (meth) acrylates can be used alone or in combination. Among these, it is preferable to use butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, methyl (meth) acrylate, and iso-butyl (meth) acrylate. These (meth) acrylates are generally in the component (A) in an amount in the range of 0 to 79.9% by weight, preferably 0 to 69.5% by weight, more preferably 0 to 48.8% by weight. Can be used in

  Further, in the main acrylic polymer (A) used in the present invention, in addition to the above acrylic monomer, a compound having active hydrogen such as an amino group, an amide group, an imide group or the like can be used. Examples of such compounds having active hydrogen include amino group-containing monomers such as (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate: maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, Mention may be made of maleimide group-containing monomers such as maleimide monomers such as butyl maleimide, hexyl maleimide, octyl maleimide, dodecyl maleimide, stearyl maleimide, phenyl maleimide and cyclohexyl maleimide. Furthermore, vinyl acetate; (meth) acrylonitrile; cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate; styrene, methylstyrene, dimethylstyrene, trimethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptyl Styrene monomers such as alkyl styrene such as styrene and octyl styrene, fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodostyrene, nitrostyrene, acetylstyrene and methoxystyrene; glycidyl (meth) acrylate It can be used in a range that does not impair the effects, preferably 0 to 5% by weight.

  The main acrylic polymer (A) used in the present invention has substantially no acidic group. Here, “having no acidic group” means that no monomer having an acidic group is intentionally added during copolymerization, and it is usually 0.5 or less in terms of the acid value of the resulting polymer. Examples of the monomer having an acidic group include a monomer having a carboxyl group such as (meth) acrylic acid, maleic acid, and itaconic acid, a monomer having a phosphoric acid group, and a monomer having a sulfuric acid group. In the present invention, the main acrylic polymer (A) is not copolymerized with the acidic group-containing monomer as described above. Since the acid group-containing monomer is not copolymerized in this way, the main acrylic polymer (A) of the present invention does not corrode even if it is in direct contact with the wiring made of metal or metal oxide. The pressure-sensitive adhesive of the invention can be given a characteristic that the resistance value of the wiring is not changed over a long period of time.

Further, the main acrylic monomer (A) used in the present invention has a weight average molecular weight of 50,000 or more and less than 400,000, preferably 200,000 to 380,000.
The pressure-sensitive adhesive that has been used in the past used a high molecular weight acrylic polymer having a weight average molecular weight of about 400,000 to 1,600,000. By using the main acrylic monomer (A) having a low weight average molecular weight, the pressure-sensitive adhesive becomes soft and the shape following property is improved, and further, it is difficult to entrap bubbles when sticking a pressure-sensitive adhesive sheet using this pressure-sensitive adhesive. . Even if the main acrylic polymer (A) having a weight average molecular weight of less than 50,000 is used, sufficient cohesive force cannot be obtained.

  In the present invention, when the main acrylic polymer (A) as described above is produced, the glass transition temperature (Tg) of the main acrylic polymer obtained by the Fox formula obtained is usually −70 ° C. to 0 ° C., The monomer is preferably selected to be within the range of -70 ° C to -30 ° C. By using the main acrylic polymer (A) having such a glass transition temperature (Tg), a pressure-sensitive adhesive having excellent adhesive strength at room temperature can be obtained.

The pressure-sensitive adhesive of the present invention contains a low molecular weight (meth) acrylic polymer (B) having a hydrogen-bonding functional group and having substantially no acidic group and a weight average molecular weight of less than 100,000.
Here, as the hydrogen-bonding functional group-containing monomer that forms the low molecular weight (meth) acrylic polymer, any one of an amino group-containing monomer, an amide group-containing monomer, a nitrogen-based heterocyclic ring-containing monomer, and a cyano group-containing monomer is used. Is preferred.

Examples of amino group-containing monomers include (meth) acrylamide, dimethylaminoethyl (meth) acrylate, and diethylaminoethyl (meth) acrylate.
Examples of amide group-containing monomers include (meth) acrylamide and acetoacryl (meth) acrylic acid.

Further, examples of the nitrogen-based heterocyclic ring-containing monomer include vinyl pyrrolidone and acryloylmorpholine.
Moreover, cyano (meth) acrylate can be mentioned as an example of a cyano group containing monomer.
Moreover, it is also possible to use the above-mentioned hydroxyl group-containing monomer as the hydrogen bond functional group-containing monomer.
These can be used alone or in combination.

  The low molecular weight (meth) acrylic polymer (B) used in the present invention is usually a copolymer of the above-mentioned hydrogen bonding functional group-containing monomer and another monomer.

  Examples of other monomers used herein include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso -Butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) ) Acrylate, decyl (meth) acrylate, undeca (meth) acrylate, dideca (meth) acrylate etc. aliphatic (meth) acrylates; cyclohexyl (meth) acrylate, isobornyl (meth) acrylate etc. Alicyclic (meth) acrylates; aromatic (meth) acrylates such as benzyl (meth) acrylate and phenyl (meth) acrylate; styrene, methylstyrene, dimethylstyrene, trimethylstyrene, propylstyrene, butylstyrene, hexyl Styrenic monomers such as styrene, alkyl styrene such as heptyl styrene and octyl styrene, fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodinated styrene, nitrostyrene, acetylstyrene and methoxystyrene; glycidyl (meth) acrylate, Examples thereof include vinyl acetate and acrylonitrile. In the present invention, methyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and the like can be preferably used. These monomers can be used alone or in combination.

  In the low molecular weight (meth) acrylic polymer (B) used in the present invention, the hydrogen bondable functional group-containing monomer and the other monomer are usually in a weight ratio of 0.1 to 20: 99.9 to 80, preferably Is copolymerized in a weight ratio of 0.5 to 15: 99.5 to 85.

  The low molecular weight (meth) acrylic polymer (B) used in the present invention has a weight average molecular weight (Mw) of less than 100,000, preferably 5,000 or more and less than 50,000. When the low molecular weight (meth) acrylic polymer (B) having such a weight average molecular weight (Mw) is used together with the above main acrylic polymer (A), it acts like a pseudo-crosslinking agent and is good. Cohesive force and step following ability are developed.

  In addition, the low molecular weight (meth) acrylic polymer (B) used in the present invention also has substantially no acidic group. Here, having no acidic group is synonymous with that in the main acrylic monomer (A). Thus, since the low molecular weight (meth) acrylic polymer (B) used in the present invention is not copolymerized with an acidic group-containing monomer, the low molecular weight (meth) acrylic polymer (B) of the present invention is Even if it is in direct contact with a wiring made of a metal or metal oxide, these are not corroded, and the pressure-sensitive adhesive of the present invention can be given a characteristic that the resistance value of the wiring is not changed over a long period of time.

  In the present invention, when the low molecular weight (meth) acrylic polymer (B) as described above is produced, the glass transition temperature (Tg) of the low molecular weight (meth) acrylic polymer obtained by the Fox formula obtained is usually The monomer is selected so that it falls within the range of 50 ° C to 110 ° C, preferably 60 ° C to 100 ° C. By using the low molecular weight (meth) acrylic polymer (B) having such a glass transition temperature (Tg), a pressure-sensitive adhesive having excellent adhesive strength at room temperature can be obtained.

  Particularly in the pressure-sensitive adhesive of the present invention, the main acrylic polymer (A) and the low molecular weight (meth) acrylic polymer (B) are mixed and used, but the glass transition temperature of the main acrylic polymer (A) at this time is used. The difference [(Tg-2)-(Tg-1)] between (Tg-1) and the glass transition temperature (Tg) of the low molecular weight (meth) acrylic polymer (B) is usually 50 ° C. or higher, preferably 100 By making it in the range of -180 degreeC, it can be set as the adhesive excellent in whitening resistance, form followability, and foaming resistance.

  The pressure-sensitive adhesive of the present invention uses the main acrylic polymer (A) and the low molecular weight (meth) acrylic polymer (B). In this pressure-sensitive adhesive, the weight average molecular weight of the main acrylic polymer (A) is used. And the weight average molecular weight of the low molecular weight (meth) acrylic polymer (B) has a relationship of A> B, the weight average molecular weight of the main acrylic polymer (A) and the low molecular weight (meth) acrylic It is preferable to select the main acrylic polymer (A) and the low molecular weight (meth) acrylic polymer (B) so that the difference from the weight average molecular weight of the polymer (B) is in the range of 80,000 to 390,000. .

  The main acrylic polymer (A) and the low molecular weight (meth) acrylic polymer (B) can be produced by a known method, but are preferably produced by solution polymerization. In the solution polymerization, for example, ethyl acetate, methyl ethyl ketone, toluene, acetone or the like can be used as a polymerization solvent. Specifically, a polymerization solvent and a monomer are charged into a reaction vessel, a polymerization initiator is added in an inert gas atmosphere such as nitrogen gas, and the reaction is performed at a reaction temperature of about 50 to 90 ° C. and allowed to react for 4 to 20 hours.

  Examples of the reaction initiator used for solution polymerization include azo initiators and peroxide initiators. These initiators are usually used in an amount in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the monomer. Further, a polymerization initiator, a chain transfer agent, a monomer, and a solvent may be appropriately added during the polymerization reaction.

Under the above conditions, the weight average molecular weight can be adjusted by adjusting the reaction conditions such as the type of solvent used, the type and amount of polymerization initiator, the reaction time, and the reaction temperature in accordance with known techniques.
The pressure-sensitive adhesive of the present invention further contains an isocyanate-based crosslinking agent (C).

  Examples of the isocyanate-based crosslinking agent (C) used in the present invention include molecules such as tolylene diisocyanate, xylylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate. A compound having two or more isocyanate groups: a compound obtained by addition reaction with a polyhydric alcohol such as trimethylolpropane or pentaerythritol, an isocyanurate compound, a burette type compound, and a known polyether polyol or polyester polyol, Two or more isocyanates in a urethane prepolymer type molecule that has undergone addition reaction with acrylic polyol, polybutadiene polyol, polyisoprene, etc. It includes a compound having a sulfonate group.

  Among these, xylylene diisocyanate and its trimethylolpropane adduct are preferable in that it can improve conformability to the adherend and reduce entrainment of bubbles during bonding, and can suppress outgassing at high temperatures, In addition, hexamethylene diisocyanate, its trimethylolpropane adduct, and isocyanurate are preferable because they can improve the followability of the step on the attachment surface and improve the heat-resistant foaming property.

Such isocyanate-based crosslinking agents (C) can be used alone or in combination.
By blending the isocyanate-based crosslinking agent (C) in this way, the cohesive force of the pressure-sensitive adhesive is improved, and even if air bubbles are slightly involved at the time of pasting, expansion of the air bubbles can be suppressed.

  The pressure-sensitive adhesive of the present invention is 0.1 to 15 weight percent of the low molecular weight (meth) acrylic polymer (B) with respect to the main acrylic polymer (A) and 100 weight parts of the main acrylic polymer (A). Parts, preferably 1 to 10 parts by weight, and 0.1 to 2 parts by weight, preferably 0.1 to 1 part by weight of the isocyanate-based crosslinking agent (C).

  In the pressure-sensitive adhesive of the present invention, an antioxidant, a light stabilizer, a metal corrosion inhibitor, a tackifier, a plasticizer, an antistatic agent, a crosslinking accelerator, as long as the effect of the pressure-sensitive adhesive of the present invention is not impaired. A reworking agent or the like can also be blended.

  The pressure-sensitive adhesive thus obtained can be used for bonding various members by coating and drying after dilution to an appropriate concentration, in the same manner as known pressure-sensitive adhesives. The coating solution containing the main acrylic polymer (A), the low molecular weight (meth) acrylic polymer (B), and the isocyanate crosslinking agent (C) used in the present invention in the solvent is the weight of the main acrylic polymer (A). Since the average molecular weight (Mw) is low, the concentration of non-volatile components can be adjusted to a desired concentration using a solvent such as ethyl acetate, methyl ethyl ketone, acetone, and toluene. Therefore, by using the pressure-sensitive adhesive of the present invention, the thickness of the pressure-sensitive adhesive after coating can be easily set to a desired thickness. In particular, since the pressure-sensitive adhesive of the present invention can easily prepare a solution having a high nonvolatile content, for example, the nonvolatile content can be adjusted within a range of 10 to 70%, preferably 30 to 60%. A pressure-sensitive adhesive layer having a desired thickness can be formed with a small number of coatings. Further, by using a solution having a high nonvolatile content as described above, the leveling property of the coating film after coating and drying is improved, and the drying time is shortened and the workability is improved. Furthermore, since the amount of volatile solvent is small, the burden on the environment is also reduced.

  Utilizing such characteristics, the pressure-sensitive adhesive sheet of the present invention is coated with the above pressure-sensitive adhesive to a thickness in the range of 25 to 1000 μm, preferably in the range of 25 to 500 μm, and after removing the solvent. It is obtained by curing.

  This pressure-sensitive adhesive sheet is usually made of a support (eg, release-treated PET or the like) whose surface has been subjected to a pressure-sensitive adhesive coating solution whose non-volatile content is adjusted to 10 to 70%, preferably 30 to 60%. After the surface is coated so that the dry thickness is within the range of 10 to 1000 μm, preferably within the range of 25 to 500 μm and the solvent is removed, the surface is formed on the surface of the formed adhesive layer. It is obtained by sticking the peel-treated cover film and usually curing at a temperature of 0 to 50 ° C. for 1 to 10 days.

The gel fraction of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet thus obtained is usually in the range of 50 to 80%, preferably 60 to 70%.
The pressure-sensitive adhesive sheet thus obtained can be attached to various members, and is particularly suitable for attaching a laminate for a touch panel in which different types of members are attached.

As shown in FIGS. 1 and 2, the touch panel unit includes a resistive touch panel unit (see FIG. 1) and a capacitive touch panel unit (see FIG. 2).
FIG. 1 shows an example of a resistive film type touch panel unit 10-1.
As shown in FIG. 1, the resistive touch panel unit 10-1 bonds the upper stacked body 11-1 and the lower stacked body 13-1 so that the gap 34 is formed by the bonding agent 30. A spacer 32 is disposed in the gap 34 in order to effectively secure the gap width.

  In the upper laminate 11-1, a transparent conductive film 27-1 made of metal or metal oxide is disposed facing the gap 34. The transparent conductive film 27-1 is made of a conductive material having transparency such as ITO (indium tin oxide), ATO (antimony tin oxide), tin oxide, and is usually made of polyethylene terephthalate (as shown in FIG. It is formed on the surface of the upper electrode support 25-1 made of a transparent member such as PET, polycarbonate (PC), polymethyl methacrylate (PMMA) or glass.

  A surface support 21-1 is disposed on the outermost surface of the upper laminate 11-1, and this surface support 21-1 is usually a transparent member such as highly transparent glass, polycarbonate (PC), or polyethylene. It is a transparent plastic film or plastic plate such as terephthalate (PET), polymethyl methacrylate (PMMA), or cycloolefin polymer (COP).

In order to adhere the surface support 21-1 and the upper electrode support 25-1, an adhesive layer 23-1 made of the adhesive of the present invention is formed.
Similarly, the lower laminated body 13-1 is formed with a transparent conductive film 27-2 made of a metal or a metal oxide so as to face the gap 34. The transparent conductive film 27-2 includes ITO, ATO, It is formed of a conductive material having transparency such as tin oxide. Usually, as shown in FIG. 1, a transparent film such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), or transparent such as glass It is formed on the surface of the lower electrode support 25-2 made of a member.

  A deep surface support 21-2 is formed at the deepest portion of the lower laminated body 13-1 so as to face the surface of the display. The deep surface support 21-2 is a transparent member such as glass or It is formed from highly transparent members such as polycarbonate (PC), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), a transparent plastic film such as cycloolefin polymer (COP), and a plastic plate.

In the lower laminate 13-1, an adhesive layer 23-2 made of the adhesive of the present invention is formed in order to adhere the deep surface support 21-2 and the lower electrode support 25-2.
Moreover, the adhesive of this invention may be used as the bonding agent 30. FIG.

  The transparent conductive films 27-1 and 27-2 are formed with a circuit, and by applying pressure with a finger or the like from above the surface support 21-1, the gap 34 where the pressure is applied disappears. Then, the transparent conductive films 27-1 and 27-2 are in contact with each other to be energized to detect the pressurized portion.

  In the resistive film type touch panel unit 10-1, the thickness of the surface support 21-1 is usually 25 to 2000 μm, and the thickness of the upper transparent electrode film 27-1 is usually 25 to 100 μm. The thickness of the body 25-1 is usually 25 to 2000 μm. As described above, the thickness of the pressure-sensitive adhesive layer 23-1 for laminating them is in the range of 10 to 1000 μm, preferably in the range of 25 to 500 μm.

Similarly, in the resistive film type touch panel unit, the thickness of the deep support 21-2 is usually 25 to 2000 μm, and the thickness of the lower transparent electrode film 27-2 is usually 25 to 100 μm. The thickness of the body 25-2 is usually 25 to 2000 μm. The thickness of the pressure-sensitive adhesive layer 23-2 on which these are laminated is in the range of 25 to 1000 μm, preferably in the range of 25 to 500 μm, as described above.
Further, in the resistive film type touch panel unit 10-1, the width of the gap formed at the center is usually in the range of 1 to 2000 μm.

  On the other hand, the capacitive touch panel unit 10-2 generally includes a central support 60 made of a highly transparent member such as glass, polycarbonate (PC), polyethylene terephthalate, cycloolefin polymer (COP), or polymethyl methacrylate. In many cases, the upper laminate 15-1 and the lower laminate 15-2 are arranged to be sandwiched.

  In the upper laminate 15-1 of the capacitive touch panel 10-2, a transparent conductive film 57-1 is disposed in contact with the central support 60, and the outermost surface is a cover glass or polyethylene terephthalate (PET). A surface support 51-1 made of a light transmissive member such as polycarbonate (PC), polymethyl methacrylate (PMMA), or cycloolefin polymer (COP) is disposed. The pressure-sensitive adhesive layer 53-1 made of the pressure-sensitive adhesive sheet of the present invention is disposed so as to bond the transparent conductive film 57-1 and the surface support 51-1. It is in direct contact with the membrane 57-1.

On the other hand, in the upper laminate 15-2 in the capacitive touch panel unit 10-2, the transparent conductive film 57-2 is disposed in contact with the central support 60, and in the deepest part, a cover glass or polyethylene is provided. A surface support 51-2 made of a light transmitting member such as terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), cycloolefin polymer (COP) is disposed. The pressure-sensitive adhesive layer 53-2 made of the pressure-sensitive adhesive sheet of the present invention is arranged so as to bond the transparent conductive film 57-2 and the deepest surface support 51-2, and the pressure-sensitive adhesive layer 53-2 In direct contact with the transparent conductive film 57-2.
In the capacitive touch panel unit 10-2, the deepest surface support 51-2 is arranged to face the display.

  In the capacitive touch panel unit 10-2, the thickness of the upper laminate 51-1 is usually 175 to 3000 μm, and the thickness of the upper transparent electrode film 57-1 is usually 25 to 100 μm. The thickness of the adhesive layer 53-1 to be bonded is 10 to 1000 μm as described above. In the lower laminate 15-2, the thickness of the lower transparent electrode film 57-2 is usually 25 to 100 μm, and the thickness of the deepest surface support 51-2 is usually 25 to 2000 μm. As described above, the thickness of the pressure-sensitive adhesive layer for adhering is 25 to 1000 μm. In addition, the thickness of the central support 60 between the upper laminate 15-1 and the lower laminate 15-2 is usually in the range of 25 to 2000 μm.

The upper electrode film 51-1 and the lower electrode film 51-2 form a circuit. Further, in the capacitive touch panel unit 10-2 shown in FIG. 2, the upper electrode film 10-2 is formed as two series of circuits provided independently in the X-axis direction and the Y-axis direction, respectively. The laminated body 15-2 can also be omitted.
In the capacitive touch panel, the contact position is detected by reading the change in the capacitance of the contact portion caused by the finger touching the surface of the touch panel unit 10-2.

For the touch panel unit as described above, for example, frame printing is performed on the surface of the edge surface support 51-1 that is in contact with the adhesive shown in FIG. This frame printing portion is shown in an enlarged manner in FIG. In FIG. 3, the frame printing portion is indicated by the number 62. The thickness (t ₀ ) of the frame printing portion 62 is usually 10 to 50 μm, and its cross section is formed in a substantially rectangular shape. Since the pressure-sensitive adhesive layer 53-1 is formed by sticking the above-mentioned pressure-sensitive adhesive sheet of the present invention to the surface support 51-1, the pressure-sensitive adhesive layer formed on the pressure-sensitive adhesive sheet is hard and has poor shape following properties. As shown in FIG. 4 (a), the adhesive layer 53-1 is located between the surface support 51-1 and the frame printing portion 62 at the end of the frame printing portion 62 and between the surface support 51-1. A gap 64 that is not in contact with any of the edges is formed. Originally, as shown in FIG. 4 (b), the adhesive layer 53-1 must be in close contact with the edge portions of the surface support 51-1 and the frame printing portion 62 without forming the gap 64.

  However, in the pressure-sensitive adhesive based on a pressure-sensitive adhesive having a weight average molecular weight of 400,000 to 1.6 million as in the past, the shape of the pressure-sensitive adhesive layer cannot be changed due to such a very fine shape change, and the gap 64 is formed. It will be formed.

  The pressure-sensitive adhesive layer 53-1 constituting the laminate for a touch panel of the present invention in which a surface support, a pressure-sensitive adhesive layer, and a transparent electrode film (which may have a support) are laminated has a specific composition as described above. And a main acrylic polymer (A) having a weight average molecular weight (Mw) of 50,000 or more and less than 400,000 and a low molecular weight (meth) acrylic polymer (B) having a specific composition and a weight average molecular weight of less than 100,000 ) Are cross-linked with an isocyanate cross-linking agent (C), and have excellent shape followability, and no voids 64 are formed around the frame print portion 62.

  Moreover, when the laminated body for touchscreens of this invention uses the member which is easy to generate | occur | produce outgas like polycarbonate (PC) as a support body 51-2 as shown in FIG. 5, on the conditions of 80 degreeC of heat test conditions, for example When the test is performed, outgas from the support may be generated, and bubbles 66 may be generated between the support and the pressure-sensitive adhesive layer. Even if a support that does not generate outgas is used, bubbles 68 may be involved when the support and the pressure-sensitive adhesive layer are bonded to each other, and if this bubble grows due to a temperature change, it will cause foaming. The pressure-sensitive adhesive of the present invention uses a main acrylic polymer (A) having a specific composition and having a weight average molecular weight (Mw) of 50,000 or more and less than 400,000, and has a specific composition and a weight average molecular weight of less than 100,000. The low molecular weight (meth) acrylic polymer (B) is cross-linked with the isocyanate cross-linking agent (C), and thus has a very high cohesive force. Foaming due to the growth of entrained bubbles can be suppressed by a high cohesive force. Therefore, in the laminated body for touch panels of this invention, the above foaming can be hardly observed.

  Moreover, in the laminated body for touch panels, when a member is left under durability test conditions (60 ° C., 90%), moisture may enter from the support side and the end as shown in FIG. Under high temperature conditions, the infiltrated moisture does not precipitate, but when the temperature decreases, the infiltrated moisture precipitates, forming visible droplets, and the touch panel laminate is whitened. The haze value increases. The pressure-sensitive adhesive layer forming the laminate for a touch panel of the present invention has a specific composition, so that even if moisture enters from the support layer or the edge, the moisture is dispersed in the pressure-sensitive adhesive layer and is visible. Therefore, the haze value is hardly increased due to the whitening phenomenon.

  Furthermore, since the pressure-sensitive adhesive of the present invention does not substantially contain an acidic group, even if this pressure-sensitive adhesive directly contacts a transparent conductive film made of a metal or metal oxide, the resistance value of the transparent electrode film changes. Is about 10% at the maximum, and this amount of change is an amount which does not cause any problem in driving the touch panel.

  As described above, the laminate for a touch panel of the present invention has a main acrylic polymer (A) having a specific composition as an adhesive and a weight average molecular weight of 50,000 to less than 400,000, and a low molecular weight (meth) having a specific group. The support and the transparent conductive film are adhered using an adhesive having an acrylic polymer (B) and an isocyanate-based cross-linking agent (C), and has an excellent shape following property. No gaps are formed in the frame printed part, and both foaming due to entrainment and foaming due to outgas can be suppressed. Furthermore, since no moisture is precipitated, the pressure-sensitive adhesive layer is whitened and the haze value is increased. I don't have to.

EXAMPLES Next, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto.
The weight average molecular weight, gel fraction, non-volatile content, wet heat whitening property, heat-resistant foaming property, ITO corrosivity, coating property, workability, step following property, and adhesive strength of the pressure sensitive adhesive were measured by the following methods.

〔Measuring method〕
<Molecular weight>
The weight average molecular weight (Mw) in terms of standard polystyrene was determined using gel permeation chromatography (GPC).
Measuring condition apparatus: HLC-8120GPC (manufactured by Tosoh Corporation)
Column: TSK-GEL HXL-H (guard column, manufactured by Tosoh Corporation)
TSK-GEL 7000HXL (manufactured by Tosoh Corporation)
TSK-GEL GMHXL (manufactured by Tosoh Corporation)
TSK-GEL GMHXL (manufactured by Tosoh Corporation)
TSK-GEL G2500HXL (manufactured by Tosoh Corporation)
Diluted with tetrahydrofuran so that the sample concentration is 1.0 mg / cm ³ Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 cm ³ / min
Column temperature: 40 ° C

<Gel fraction>
About 0.1 g of adhesive after aging at 23 ° C. for 7 days was collected in a sampling bottle, 30 cc of ethyl acetate was added and shaken for 4 hours, and then the contents of this sample bottle were filtered through a 200 mesh stainless steel wire mesh. The residue on the wire mesh was dried at 100 ° C. for 2 hours, and the dry weight was measured.
Gel fraction (%) = (Dry weight / Adhesive sampling weight) × 100

<Haze>
The release sheet on one side of the obtained pressure-sensitive adhesive sheet was peeled off, and a 25 μm-thick polyethylene terephthalate film was bonded together and cut into a size of 50 mm × 50 mm. Next, the other release film was peeled off, bonded to a 2 mm thick PC plate, treated in an autoclave at 50 ° C. and 5 atm for 20 minutes, and then allowed to stand for 1 hour to prepare a test piece.

After measuring the haze before the endurance test of the prepared test piece, it was allowed to stand at 60 ° C., 90% environment, 85 ° C., 85% environment. After 500 hours, the test piece was taken out and allowed to stand at room temperature for 1 hour, and then the haze was measured to determine the difference from the haze before the durability test.
For the measurement of haze, MH-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.) was used.

<Foaming>
The release sheet on one side of the obtained pressure-sensitive adhesive sheet was peeled off, and a 25 μm-thick polyethylene terephthalate film on which ITO was deposited was bonded and cut into a size of 50 mm × 50 mm. Next, the other release film was peeled off, bonded to a 2 mm thick PC plate, treated in an autoclave at 50 ° C. and 5 atm for 2 minutes, and then allowed to stand for 1 hour to prepare a test piece.

After the haze for the durability test of the prepared test piece was measured, it was allowed to stand at 60 ° C., 90% environment, 85 ° C., dry environment, 85 ° C., 85% environment. The test piece after the elapse of 500 hours was taken out and allowed to stand at room temperature for 1 hour, and then the degree of foaming was visually confirmed.
The evaluation criteria are as follows:

(Evaluation) (Content)
A: No bubbles can be visually confirmed in the pressure-sensitive adhesive layer.
○: Slight bubbles can be visually confirmed.
Δ: Although practical, bubbles can be clearly observed visually.
X: Large bubbles can be confirmed. Further, the pressure-sensitive adhesive layer floats from the base material or the adherend.

<ITO resistance change rate>
In the foaming test, the resistance value before the foaming test was measured in advance, and then the resistance value of the test piece placed in an environment of 85 ° C. and 85% was measured to obtain the rate of change of the resistance value.
The resistance value was measured using a tester (manufactured by Sanwa Denki Keiki Co., Ltd., Digital Multimeter PC510).

<Adhesive strength to ITO>
A peeled polyethylene terephthalate film (PET film) on one side of the obtained pressure-sensitive adhesive sheet was peeled off, a 25 μm PET film was bonded, and cut into a width of 25 mm to prepare a test piece.
Next, the other peelable PET film of the test piece was peeled off and bonded to a PET film on which ITO was deposited.
The test piece was peeled off and the adhesive strength against ITO was determined from the peel strength.

<Step following capability>
The peeled PET film on one side of the obtained pressure-sensitive adhesive sheet was peeled off, a 25 μm PET film was bonded, and cut into 50 mm × 50 mm to prepare a test piece.
Next, a PET film cut to 25 mm × 25 mm is placed on a glass plate, the peeled PET film on the other side of the prepared test piece is peeled off, and the PET film on the glass plate is pasted so as to cover the entire surface. The sample was allowed to stand in an 80 ° C. environment for 500 hours and then allowed to stand at room temperature for 1 hour, and the appearance of the step portion was visually observed.

(Evaluation) (Content)
A: Bubbles cannot be visually confirmed at the stepped portion.
○: A slight amount of air bubbles can be confirmed at the stepped portion by visual attachment.
Δ: Although it is practically usable, bubbles can be clearly observed visually at the pasted stepped portion.
X: Large bubbles can be confirmed at the stepped portion. Further, the pressure-sensitive adhesive layer floats from the base material or the adherend.

<Nonvolatile content>
About 1 g of (meth) acrylic polymer solution was added to the weighed tin plate (n1), and the total weight (n2) was weighed, followed by heating at 105 ° C. for 3 hours. Thereafter, the tin plate was allowed to stand in a desiccator at room temperature for 1 hour, then weighed again, and the total weight (n3) after heating was measured. The nonvolatile content was calculated from the following formula using the obtained weight measurement values (n1 to n3).
Nonvolatile content (%) = 100 × [weight after heating (n3-n1) / weight before heating (n2-n1)]

<Synthesis example of main acrylic polymer>
[Production Example 1]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of methoxyethyl acrylate (MEA), 36 parts by weight of butyl acrylate (BA), 4 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.

Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 1 (main polymer 1) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -51 degreeC.

[Production Example 2]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of ethoxydiethylene glycol acrylate (ECA), 36 parts by weight of butyl acrylate (BA), 4 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 2 (main polymer 2) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -60 degreeC.

[Production Example 3]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 90 parts by weight of methoxyethyl acrylate (MEA), 6 parts by weight of butyl acrylate (BA), 4 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 3 (main polymer 3) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -48 degreeC.

[Production Example 4]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of methoxyethyl acrylate (MEA), 33 parts by weight of butyl acrylate (BA), 7 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 4 (main polymer 4) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -49 degreeC.

[Production Example 5]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 20 parts by weight of methoxyethyl acrylate (MEA), 76 parts by weight of butyl acrylate (BA), 4 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 5 (main polymer 5) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -52 degreeC.

[Production Example 6]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube, 20 parts by weight of methoxyethyl acrylate (MEA), 16 parts by weight of butyl acrylate (BA), 60 parts by weight of 2-ethylhexyl acrylate (2-EHA) Then, 4 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 6 (main polymer 6) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -61 degreeC.

[Production Example 7]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of methoxyethyl acrylate (MEA), 39 parts by weight of butyl acrylate (BA), 1 part by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 7 (main polymer 7) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -52 degreeC.

[Production Example 8]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of methoxyethyl acrylate (MEA), 37 parts by weight of butyl acrylate (BA), 3 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 8 (main polymer 8) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -50 degreeC.

[Production Example 9]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of methoxyethyl acrylate (MEA), 35 parts by weight of butyl acrylate (BA), 5 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 9 (main polymer 9) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -50 degreeC.

[Production Example 10]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of methoxyethyl acrylate (MEA), 31 parts by weight of butyl acrylate (BA), 9 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 10 (main polymer 10) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -49 degreeC.

[Production Example 11]
A reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube was charged with 60 parts by weight of methoxyethyl acrylate (MEA), 39 parts by weight of butyl acrylate (BA), 1 part by weight of acrylic acid (AA) and ethyl acetate ( EtAc) 100 parts by weight and methyl ethyl ketone (MEK) 20 parts by weight were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 11 (main polymer 11) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -51 degreeC.

[Production Example 12]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 10 parts by weight of methoxyethyl acrylate (MEA), 86 parts by weight of butyl acrylate (BA), 4 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 12 (main polymer 12) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -52 degreeC.

[Production Example 13]
In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 10 parts by weight of methoxyethyl acrylate (MEA), 86 parts by weight of 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2- 4 parts by weight of HEA, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 13 (main polymer 13) having a weight average molecular weight of 300,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -65 degreeC.

[Production Example 14]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of methoxyethyl acrylate (MEA), 36 parts by weight of butyl acrylate (BA), 4 parts by weight of 2-hydroxyethyl acrylate (2-HEA) And 120 parts by weight of ethyl acetate (EtAc) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.2 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 14 (main polymer 14) having a weight average molecular weight of 600,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -50 degreeC.

[Production Example 15]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of methoxyethyl acrylate (MEA), 36 parts by weight of butyl acrylate (BA), 4 parts by weight of 2-hydroxyethyl acrylate (2-HEA) And 150 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain a main acrylic polymer 15 (main polymer 15) having a weight average molecular weight of 30,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained main polymer is -50 degreeC.

<Synthesis of low molecular weight (meth) acrylic polymer>
[Production Example 16]
A reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube was charged with 90 parts by weight of cyclohexyl methacrylate (CHMA), 10 parts by weight of dimethylaminoethyl methacrylate (DM) and 100 parts by weight of toluene, and nitrogen gas was introduced. The temperature was raised to 85 ° C.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 1 (low molecular weight body 1) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 60 degreeC.

[Production Example 17]
A reactor equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube was charged with 90 parts by weight of cyclohexyl methacrylate (CHMA), 10 parts by weight of acrylamide (AM) and 100 parts by weight of toluene, while introducing nitrogen gas. The temperature was raised to ° C.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 2 (low molecular weight body 2) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 73 degreeC.

[Production Example 18]
A reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube was charged with 90 parts by weight of cyclohexyl methacrylate (CHMA), 10 parts by weight of acryloylmorpholine (ACMO) and 100 parts by weight of toluene while introducing nitrogen gas. The temperature was raised to 87 ° C.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 3 (low molecular weight body 3) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 72 degreeC.

[Production Example 19]
A reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube was charged with 90 parts by weight of cyclohexyl methacrylate (CHMA), 10 parts by weight of n-vinylpyrrolidone (n-VP) and 100 parts by weight of toluene, and nitrogen gas The temperature was raised to 88 ° C. while introducing.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 4 (low molecular weight body 4) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 67 degreeC.

[Production Example 20]
A reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube was charged with 90 parts by weight of methyl methacrylate (MMA), 10 parts by weight of dimethylaminoethyl methacrylate (DM) and 100 parts by weight of toluene, and nitrogen gas was introduced. The temperature was raised to 89 ° C.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 5 (low molecular weight body 5) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 94 degreeC.

[Production Example 21]
A reactor equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube was charged with 90 parts by weight of isobornyl acrylate (IBXA), 10 parts by weight of dimethylaminoethyl methacrylate (DM) and 100 parts by weight of toluene, and nitrogen gas. The temperature was raised to 90 ° C. while introducing.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 6 (low molecular weight body 6) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 87 degreeC.

[Production Example 22]
A reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube was charged with 40 parts by weight of cyclohexyl methacrylate (CHMA), 50 parts by weight of methyl methacrylate (MMA), 10 parts by weight of dimethylaminoethyl methacrylate (DM) and toluene 100. A weight part was charged, and the temperature was raised to 91 ° C. while introducing nitrogen gas.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 7 (low molecular weight body 7) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 74 degreeC.

[Production Example 23]
A reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube was charged with 97 parts by weight of cyclohexyl methacrylate (CHMA), 3 parts by weight of dimethylaminoethyl methacrylate (DM) and 100 parts by weight of toluene, and nitrogen gas was introduced. The temperature was raised to 92 ° C.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 8 (low molecular weight body 8) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 64 degreeC.

[Production Example 24]
A reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube was charged with 95 parts by weight of methyl methacrylate (MMA), 5 parts by weight of dimethylaminoethyl methacrylate (DM) and 100 parts by weight of toluene, and nitrogen gas was introduced. The temperature was raised to 93 ° C.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 9 (low molecular weight body 9) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 92 degreeC.

[Production Example 25]
A reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube was charged with 90 parts by weight of cyclohexyl methacrylate (CHMA), 10 parts by weight of acrylic acid (AA) and 100 parts by weight of toluene while introducing nitrogen gas. The temperature was raised to 94 ° C.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 10 (low molecular weight body 10) having a weight average molecular weight of 10,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 97 degreeC.

[Production Example 26]
A reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube was charged with 90 parts by weight of cyclohexyl methacrylate (CHMA), 10 parts by weight of dimethylaminoethyl acrylate (DM) and 100 parts by weight of toluene, and nitrogen gas was introduced. The temperature was raised to 95 ° C.
Next, 0.5 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with toluene and adjusted to a solid content concentration of 30% to obtain a low molecular weight (meth) acrylic polymer 11 (low molecular weight body 11) having a weight average molecular weight of 120,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained low molecular weight body is 94 degreeC.

[Examples 1 to 21]
The main polymer and the low molecular weight material were mixed in the proportions (solid content) shown in Tables 3 and 4 below, and a curing agent was added to obtain an adhesive composition (solid content: 30% by weight). ).
The obtained pressure-sensitive adhesive composition was applied onto a polyethylene terephthalate (PET) film that had been subjected to a release treatment so that the dry thickness was 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.
Using the obtained pressure-sensitive adhesive sheet, the gel fraction, haze change, foaming, step following property (step following property), ITO resistance change rate and adhesive strength against ITO were measured. The results are shown in Table 3 and Table 4 together.

[Comparative Examples 1 to 10]
The main polymer and the low molecular weight material were mixed at the ratio (solid content) shown in Table 5 below, and a curing agent was added to obtain a pressure-sensitive adhesive composition (solid content: 30% by weight).
The obtained pressure-sensitive adhesive composition was applied onto a polyethylene terephthalate (PET) film that had been subjected to a release treatment so that the dry thickness was 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.
Using the obtained pressure-sensitive adhesive sheet, the gel fraction, haze change, foaming, step following property (step following property), ITO resistance change rate and adhesive strength against ITO were measured. The results are also shown in Table 5.

10-1 ... resistive film type touch panel unit 10-2 ... capacitive touch panel unit 11-1 ... upper laminate 13-1 ... lower laminate 15-1 ... upper part Laminate 15-2 ... Lower laminate 21-1 ... Surface support 21-2 ... Deep surface support 23-1 ... Adhesive layer 23-2 ... Adhesive layer 25 -1 ... upper electrode support 25-2 ... lower electrode support 27-1 ... transparent conductive film 27-2 ... transparent conductive film 30 ... bonding agent 32 ... spacer 34 ... Gap 51-1 ... Surface support 51-2 ... Surface support 53-1 ... Adhesive layer 57-1 ... Transparent conductive film 57-2 ... Transparent conductive film 60 ... Center support 62 ... Frame printing part 64 ... Gap 66 ... Bubble 68 ... Bubble

Claims (20)

The following components (a-1) and (a-2)
(A-1) Alkoxy (meth) acrylate 20 to 99.9% by weight
(A-2) Monomer having a crosslinkable functional group 0.1 to 10% by weight
A main acrylic polymer (A) having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which is substantially free of acidic groups obtained by copolymerizing a monomer containing styrene, and 100 parts by weight of the main acrylic polymer (A) Against
Low molecular weight (meth) acrylic polymer (B) having a hydrogen-bonding functional group and having substantially no acidic group and a weight average molecular weight of less than 100,000: 0.1 to 15 parts by weight;
Isocyanate-based crosslinking agent (C): 0.1 to 2 parts by weight of an adhesive (however, the weight average molecular weight of the main acrylic polymer (A) in the adhesive and the low molecular weight ( (It has a relationship of A> B with the weight average molecular weight of the (meth) acrylic polymer (B)).   The pressure-sensitive adhesive according to claim 1, wherein the monomer (a-2) having a crosslinkable functional group forming the main acrylic polymer (A) is a hydroxyl group-containing monomer.   The hydrogen bonding functional group introduced into the low molecular weight (meth) acrylic polymer (B) is selected from the group consisting of an amino group-containing monomer, an amide group-containing monomer, a nitrogen-based heterocyclic ring-containing monomer, and a cyano group-containing monomer. The pressure-sensitive adhesive according to claim 1, wherein the pressure-sensitive adhesive is a group introduced by copolymerizing at least one kind of monomer.   The main acrylic polymer (A) has a glass transition temperature (Tg-1) in the range of -70 ° C to 0 ° C, and the glass transition temperature (Tg-2) of the low molecular weight (meth) acrylic polymer (B). Is in the range of 50 ° C. to 110 ° C., and the glass transition temperature (Tg-2) of the low molecular weight (meth) acrylic polymer (B) and the glass transition temperature (Tg-1) of the main acrylic polymer (A). The pressure-sensitive adhesive according to claim 1, wherein the difference [(Tg-2)-(Tg-1)] is 50 ° C or higher.   The pressure-sensitive adhesive according to claim 1, wherein the pressure-sensitive adhesive is a pressure-sensitive adhesive for a capacitive touch panel that is in direct contact with a metal or metal oxide. The following components (a-1) and (a-2)
(A-1) Alkoxy (meth) acrylate 20 to 99.9% by weight
(A-2) Monomer having a crosslinkable functional group 0.1 to 10% by weight
A main acrylic polymer (A) having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which is substantially free of acidic groups obtained by copolymerizing a monomer containing styrene, and 100 parts by weight of the main acrylic polymer (A) Against
Low molecular weight (meth) acrylic polymer (B) having a hydrogen-bonding functional group and having substantially no acidic group and a weight average molecular weight of less than 100,000: 0.1 to 15 parts by weight;
Isocyanate-based crosslinking agent (C): a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness in the range of 10 to 1000 μm formed from a pressure-sensitive adhesive containing 0.1 to 2 parts by weight (however, The weight average molecular weight of the main acrylic polymer (A) in the pressure-sensitive adhesive and the weight average molecular weight of the low molecular weight (meth) acrylic polymer (B) have a relationship of A> B.)   The pressure-sensitive adhesive sheet according to claim 6, wherein the monomer (a-2) having a crosslinkable functional group forming the main acrylic polymer (A) is a hydroxyl group-containing monomer.   The hydrogen bonding functional group introduced into the low molecular weight (meth) acrylic polymer (B) is selected from the group consisting of an amino group-containing monomer, an amide group-containing monomer, a nitrogen-based heterocyclic ring-containing monomer, and a cyano group-containing monomer. The pressure-sensitive adhesive sheet according to claim 6, wherein the pressure-sensitive adhesive sheet is a group introduced by copolymerizing at least one monomer.   The main acrylic polymer (A) has a glass transition temperature (Tg-1) in the range of -70 ° C to 0 ° C, and the glass transition temperature (Tg-2) of the low molecular weight (meth) acrylic polymer (B). Is in the range of 50 ° C. to 110 ° C., and the glass transition temperature (Tg-2) of the low molecular weight (meth) acrylic polymer (B) and the glass transition temperature (Tg-1) of the main acrylic polymer (A). The pressure-sensitive adhesive sheet according to claim 6, wherein the difference [(Tg−2) − (Tg−1)] is 50 ° C. or more.   The pressure-sensitive adhesive sheet according to claim 6, wherein the pressure-sensitive adhesive forming the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive for a capacitive touch panel in direct contact with a metal or metal oxide.   The pressure-sensitive adhesive sheet according to claim 6, wherein a cover film subjected to a peeling treatment is disposed on at least one surface of the pressure-sensitive adhesive sheet. The following components (a-1) and (a-2)
(A-1) Alkoxy (meth) acrylate 20 to 99.9% by weight
(A-2) Monomer having a crosslinkable functional group 0.1 to 10% by weight
A main acrylic polymer (A) having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which is substantially free of acidic groups obtained by copolymerizing a monomer containing styrene, and 100 parts by weight of the main acrylic polymer (A) Against
Low molecular weight (meth) acrylic polymer (B) having a hydrogen-bonding functional group and having substantially no acidic group and a weight average molecular weight of less than 100,000: 0.1 to 15 parts by weight;
Isocyanate-based crosslinking agent (C): a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive containing 0.1 to 2 parts by weight (within the pressure-sensitive adhesive) The weight average molecular weight of the main acrylic polymer (A) and the weight average molecular weight of the low molecular weight (meth) acrylic polymer (B) have a relationship of A> B.) A frame-printed surface support is attached to the edge of the facing surface, and a transparent conductive film made of metal or metal oxide or metal with electrode support or metal oxide is attached to the other surface of the adhesive sheet. A laminate for a touch panel, characterized in that it is adhered.   The laminate for a touch panel according to claim 12, wherein the laminate for a touch panel is a member forming a capacitive touch panel.   The laminate for a touch panel according to claim 12, wherein a thickness of the frame printing is in a range of 10 to 50 µm.   13. The touch panel according to claim 12, wherein the transparent electrode film is a wiring pattern using ITO, ATO or tin oxide as a metal oxide, and the adhesive sheet is in direct contact with the wiring pattern. Laminated body.   The laminate for a touch panel according to claim 12, wherein the thickness of the surface support is in the range of 25 to 2000 µm.   The laminate for a touch panel according to claim 12, wherein the transparent conductive film has a thickness in the range of 25 to 100 µm.   The laminate for a touch panel according to claim 12, wherein the monomer (a-2) having a crosslinkable functional group forming the main acrylic polymer (A) is a hydroxyl group-containing monomer.   The hydrogen bonding functional group introduced into the low molecular weight (meth) acrylic polymer (B) is selected from the group consisting of an amino group-containing monomer, an amide group-containing monomer, a nitrogen-based heterocyclic ring-containing monomer, and a cyano group-containing monomer. The laminate for a touch panel according to claim 12, which is a group introduced by copolymerizing at least one kind of monomer.   The main acrylic polymer (A) has a glass transition temperature (Tg-1) in the range of -70 ° C to 0 ° C, and the glass transition temperature (Tg-2) of the low molecular weight (meth) acrylic polymer (B). Is in the range of 50 ° C. to 110 ° C., and the glass transition temperature (Tg-2) of the low molecular weight (meth) acrylic polymer (B) and the glass transition temperature (Tg-1) of the main acrylic polymer (A). The difference [(Tg-2)-(Tg-1)] with a) is 50 degreeC or more, The laminated body for touchscreens of Claim 12 characterized by the above-mentioned.