WO2021103681A1 - Hardening coating solution for flexible cover plate - Google Patents

Abstract

Disclosed is a hardening coating solution for a flexible cover plate. Raw materials of the hardening coating solution comprise, in parts by weight, 40-50 parts of a pre-polymer, 0.8-1.4 parts of an active monomer, 0.5-1 part of a photo-initiator and 30-40 parts of a solvent. The hardening coating solution is obtained by mixing the raw materials, and the hardening coating solution is applied to a CPI film and cured by means of ultraviolet light. Same can be used for a flexible cover plate and has a high hardness and abrasive resistance in addition to a high toughness.

Description

A hardened coating liquid for flexible cover plates Technical field

The present invention relates to the technical field of optical hardened films, and more specifically, the present invention relates to a hardened coating liquid for flexible cover plates.

Background technique

With the continuous development and improvement of curved screen technology, flexible display products that can achieve arbitrary bending will become an important development direction. The bottleneck of current hand-flexible display products is not the display itself, but the flexible cover. In fact, at present, the display part can be bent repeatedly with a certain curvature, which can meet the daily needs of users, and the touch part of the display, using thin-film metal grids or nano silver wires can also meet the requirements. Only the cover will not work.

The flexible cover must also have the ability to bend repeatedly, be transparent, ultra-thin, and have sufficient rigidity. It is not easy to find materials with these characteristics at the same time. The conventional requirement is to be able to bend more than 200,000 times under a curvature of 10 mm diameter. Of course, this is not a hard standard. In theory, it is possible for glass with a thickness of less than 100 microns to meet these characteristics, but there is still a lack of sufficient data to support the bending performance. At present, the use of colorless transparent polyimide (CPI) and hard coating is the focus of research and development to solve the problem of flexible cover plates.

CN106896424A provides a solvent-free UV curing coating solution, which includes high-official aliphatic urethane acrylate, low-official aliphatic urethane acrylate, hydroxyethyl methacrylate, 2(2-ethoxy) ethyl acrylate, and light curing Initiators and surface additives have the advantages of high light transmittance, low haze and high hardness. CN103869387B provides an ultraviolet light curing coating liquid, which includes a UV light curing resin, a reactive diluent, a photoinitiator, and an auxiliary agent. The surface roughness is less than or equal to 0.01 micrometers, and the rainbow pattern is basically invisible.

CN110358439A provides a hardening liquid for transparent polyimide hardened film, including high-functionality polyurethane acrylate, multi-functionality polyether acrylate, flexible monomer, active diluent, photoinitiator, thermal initiator, and good solvent , High boiling point poor solvents, anti-fingerprint additives and inorganic nanoparticles, with good toughness and avoid warping. Therefore, there are existing hardened films that have good hardness, wear resistance or toughness, but it is difficult to have high toughness and good hardness and wear resistance at the same time.

Summary of the invention

In order to solve the above problems, the first aspect of the present invention provides a hardened coating liquid for flexible cover plates. The preparation raw materials of the hardened coating liquid include 40-50 parts of prepolymer and 0.8 parts by weight. -1.4 parts of active monomer, 0.5-1 part of photoinitiator and 30-40 parts of solvent.

As a preferred technical solution of the present invention, the preparation method of the prepolymer includes the following steps:

Pretreatment: Add isocyanate and catalyst to the solvent and mix to obtain isocyanate solution;

Synthesis of hyperbranched polyurethane: Add the hydroxyl-terminated hyperbranched polyester dropwise to the isocyanate solution at 40～50℃, keep it for 0.5～2h to obtain the hyperbranched polyurethane mixture;

Prepolymer synthesis: The hyperbranched polyurethane mixture is heated to 60-70°C, hydroxy acrylate is added dropwise, and the temperature is lowered to 30-40°C, fluorine-substituted acrylate is added, and the temperature is maintained for 1.5-2.5 hours to obtain a prepolymer.

As a preferred technical solution of the present invention, the weight ratio of the hydroxyl-terminated hyperbranched polyester, isocyanate and hydroxyacrylate is (1.5-2.5):1:(1-1.5).

As a preferred technical solution of the present invention, the isocyanate is an alicyclic diisocyanate and/or an aliphatic diisocyanate.

As a preferred technical solution of the present invention, the hydroxy acrylate includes a difunctional hydroxy acrylate and a tetrafunctional hydroxy acrylate, and the weight ratio is 1: (0.3-0.5).

As a preferred technical solution of the present invention, the number of fluorine substitutions in the fluorine-substituted acrylate is 3-6.

As a preferred technical solution of the present invention, the reactive monomer includes a high-functionality acrylate, and the high-functionality acrylate has a functionality of 10-15.

As a preferred technical solution of the present invention, the reactive monomer further includes acrylic silicone oil, and the weight ratio of the high-functionality acrylate to acrylic silicone oil is (3 to 4): (3 to 4).

As a preferred technical solution of the present invention, the preparation raw material of the hardened coating liquid further includes modified nanoparticles, and the weight ratio of the modified nanoparticles to the active monomer is 1: (1.5-2.5).

The second aspect of the present invention provides a method for preparing a hardened coating liquid for a flexible cover plate as described above, which includes the following steps:

The preparation raw materials of the hard coating liquid are mixed to obtain the hard coating liquid.

Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a hardened coating solution for flexible cover plates, which is obtained by mixing prepolymers with hyperbranched structures and active monomers, etc. The liquid is coated on the CPI film and cured by ultraviolet light, which can be used for flexible cover plates. It has high toughness and high hardness and wear resistance; the applicant controls the preparation of hyperbranched prepolymer materials and processes , Active monomer types and modified nanoparticles can promote the balance of toughness and hardness, and further increase toughness, hardness and wear resistance.

Detailed ways

The content of the present invention can be more easily understood by referring to the following detailed description of the preferred implementation method of the present invention and the included examples. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. In case of conflict, the definition in this specification shall prevail.

As used herein, the term "prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing" or any other variations as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, product, or device containing the listed elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent in such a composition, step, method, product, or device Elements.

The conjunction "consisting of" excludes any unspecified elements, steps or components. If used in a claim, this phrase will make the claim closed so that it does not contain materials other than those described, except for the conventional impurities associated with it. When the phrase "consisting of" appears in a clause of the subject of a claim rather than immediately after the subject, it is only limited to the elements described in the clause; other elements are not excluded from the claim as a whole Beyond the requirements.

When the amount, concentration, or other value or parameter is expressed in a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing the upper limit or preferred value of any range and the lower limit of any range. Or all ranges formed by any pair of preferred values, regardless of whether the ranges are separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5" , "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

The singular form includes the plural discussion object, unless the context clearly indicates otherwise. "Optional" or "any one" means that the event or event described later can occur or not occur, and the description includes the situation where the event occurs and the situation where the event does not occur.

The approximate terms in the specification and claims are used to modify the quantity, which means that the present invention is not limited to the specific quantity, but also includes an acceptable modified part close to the quantity that does not lead to changes in related basic functions. Correspondingly, modifying a value with "about", "about", etc. means that the present invention is not limited to the precise value. In some instances, approximate terms may correspond to the accuracy of the instrument used to measure the value. In the specification and claims of the present application, the range definitions can be combined and/or interchanged, and unless otherwise stated, these ranges include all sub-ranges contained in between.

In addition, the indefinite articles "a" and "an" before an element or component of the present invention have no limitation on the quantity requirement (ie, the number of occurrences) of the element or component. Therefore, "a" or "an" should be read as including one or at least one, and elements or components in the singular form also include the plural form, unless the number clearly refers to the singular form.

The present invention is described below through specific embodiments, but is not limited to the specific examples given below.

The first aspect of the present invention provides a hardened coating liquid for flexible cover plates. The preparation raw materials of the hardened coating liquid include 40-50 parts of prepolymer and 0.8-1.4 parts of active monomer in parts by weight. Body, 0.5 to 1 part of photoinitiator and 30 to 40 parts of solvent.

In a preferred embodiment, the raw materials for preparing the hard coating liquid of the present invention include 40 parts by weight of prepolymer, 1 part of active monomer, 1 part of photoinitiator and 30 parts of solvent.

Prepolymer

In one embodiment, the preparation method of the prepolymer of the present invention includes the following steps:

Pretreatment: Add isocyanate and catalyst to the solvent and mix to obtain isocyanate solution;

Synthesis of hyperbranched polyurethane: Add the hydroxyl-terminated hyperbranched polyester dropwise to the isocyanate solution at 40～50℃, keep it for 0.5～2h to obtain the hyperbranched polyurethane mixture;

Prepolymer synthesis: The hyperbranched polyurethane mixture is heated to 60-70°C, hydroxy acrylate is added dropwise, and the temperature is lowered to 30-40°C, fluorine-substituted acrylate is added, and the temperature is maintained for 1.5-2.5 hours to obtain a prepolymer.

Preferably, the weight ratio of the hydroxyl-terminated hyperbranched polyester, isocyanate and hydroxyacrylate of the present invention is (1.5~2.5):1:(1~1.5); further, the hydroxyl-terminated hyperbranched polyester of the present invention The weight ratio of isocyanate and hydroxy acrylate is 2:1:1.3.

Hyperbranched polymers have a three-dimensional structure and a large number of active end groups. Many branched structures with approximate relative molecular mass and narrow relative molecular mass distribution extend from the core to the surroundings. The compactness of the structure gives it special physical properties and Chemical properties, it is a highly branched dendrimer with the advantages of less entanglement between molecules, low viscosity, easy film formation, high reactivity and good solubility. Hyperbranched polymers contain a large number of end groups that can be modified. A large number of active end groups have a great influence on the viscosity, solubility, thermal stability, glass transition temperature and relative molecular mass distribution of hyperbranched polymers. Hyperbranched polyesters are widely used in thermosetting resins, drugs and coatings, but their flexibility is poor and they are brittle. The hyperbranched polyester of the present invention is a hydroxyl-terminated hyperbranched polyester, which is not specifically limited. In a preferred embodiment, the hydroxyl-terminated hyperbranched polyester of the present invention is purchased from Pertorp, Sweden, under the brand name Boltorn H20.

More preferably, the catalyst of the present invention accounts for 0.4 to 0.6 wt% of the isocyanate; the catalyst of the present invention accounts for 0.5 wt% of the isocyanate.

The present invention does not specifically limit the catalyst. Examples include triethylamine (TEA), 1,4-diazabicyclo[2.2.2]octane (DABCO), dibutyltin dilaurate (DBTDL), octanoic acid Stannous (SO); In a preferred embodiment, the catalyst of the present invention is dibutyltin dilaurate.

Further preferably, the solvent of the present invention is selected from one or more of acetone, ethanol or ethyl acetate; further, the solvent of the present invention is acetone.

More preferably, the isocyanate of the present invention is an alicyclic diisocyanate and/or an aliphatic diisocyanate; further, the isocyanate of the present invention is an alicyclic diisocyanate; further, the alicyclic diisocyanate of the present invention is Isophorone diisocyanate.

Examples of alicyclic diisocyanates include, but are not limited to, 1,4-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,2-diisocyanatocyclohexane Hexane, 4,4'-bis(isocyanatocyclohexyl)methane, 2,4'-bis(isocyanatocyclohexyl)methane, isophorone diisocyanate, 1,3-bis(isocyanate Acidomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 2,4-diisocyanato-1-methylcyclohexane, 2,6-diisocyanate Cyanato-1-methylcyclohexane, 3(or 4),8(or 9)-bis(isocyanatomethyl)tricyclo[5.2.1.02,6]decane isomer mixture.

Examples of aliphatic diisocyanates include, but are not limited to, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, ten Tetramethylene diisocyanate, derivatives of lysine diisocyanate, trimethylhexane diisocyanate or tetramethylhexane diisocyanate.

In a preferred embodiment, the hydroxy acrylate of the present invention includes two-functional hydroxy acrylate and four-functional hydroxy acrylate, and the weight ratio is 1: (0.3-0.5); further, the two-functional hydroxy acrylate of the present invention The weight ratio of functional hydroxy acrylate to tetrafunctional hydroxy acrylate is 1:0.4.

Examples of difunctional hydroxy acrylates include, but are not limited to, 2-hydroxyethyl acrylate, hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, 3-hydroxy-1-adamantyl methyl Acrylate (CAS number: 115372-36-6), caprolactone acrylate.

As an example of tetrafunctional hydroxy acrylate, it includes, but is not limited to, pentaerythritol triacrylate.

The functionality is the number of functional groups in a molecule of monomer that can participate in the reaction in the condensation reaction.

In a more preferred embodiment, the difunctional hydroxy acrylate of the present invention is selected from 2-hydroxyethyl acrylate, hydroxyethyl methacrylate, 4-hydroxybutyl acrylate or 3-hydroxy- One or more of 1-adamantyl methacrylate; further, the difunctional hydroxy acrylate of the present invention includes 2-hydroxyethyl acrylate and 3-hydroxy-1-adamantyl methacrylate Base acrylate, the weight ratio is 1: (0.3-0.4); further, the weight ratio of 2-hydroxyethyl acrylate and 3-hydroxy-1-adamantyl methacrylate of the present invention is 1: 0.3.

In a further preferred embodiment, the tetrafunctional hydroxy acrylate of the present invention is pentaerythritol triacrylate.

The applicant found that by using isocyanate as a bridge, the hydroxyl acrylate is connected to the end of the hydroxyl-terminated hyperbranched polyester, so that polymerization reaction occurs at the end of the hyperbranched polyester to form a polyurethane acrylate prepolymer, which can improve the hyperbranched polyester. The disadvantage of poor toughness, and the applicant found that by controlling the double bond content in the hydroxy acrylate, it is beneficial to control the molecular weight and crosslinking degree of the prepolymer, thereby promoting the balance of toughness and hardness. This may be due to the control of the hydroxy acrylic acid. The double bond content of the ester, especially the hydroxy acrylate containing one double bond and three double bonds. Among them, the two-functional hydroxy acrylate, such as 2-hydroxyethyl acrylate, is compared with the four-functionality hydroxy acrylate. Hydroxy acrylates such as pentaerythritol triacrylate have lower steric hindrance and viscosity, and are easier to contact with the hydroxyl-terminated hyperbranched polyester. The hyperbranched polyester end is more prone to self-polymerization of a double-bonded hydroxyacrylate to form a branch. Structures with fewer chains, and as the distance from the end of the hyperbranched polyester is farther, tetrafunctional hydroxy acrylate and difunctional hydroxy acrylate with greater viscosity and steric hindrance, such as 3-hydroxy-1-adamant Alkyl methacrylate gradually participates in the reaction, and the degree of branching gradually increases, while the large side groups of 3-hydroxy-1-adamantyl methacrylate will prevent the tetrafunctional hydroxy acrylate from causing local crosslinking density to be too large , The formation of a cross-linked network with different density is beneficial to improve toughness and hardness.

In a further preferred embodiment, the weight ratio of the fluorine-substituted acrylate and the hydroxy acrylate of the present invention is 1: (10-20); further, the fluorine-substituted acrylate and the hydroxy acrylate of the present invention are The weight ratio of fluorine-substituted acrylate is 1:10; further, the number of fluorine substitutions in the fluorine-substituted acrylate of the present invention is 3-6; further, the fluorine-substituted acrylate of the present invention is trifluoroethyl methacrylate.

The applicant unexpectedly discovered that when fluorine-substituted acrylate, especially trifluoro-substituted acrylate, is added to the prepolymer, such as trifluoroethyl methacrylate, it is beneficial to the improvement of the hardness, toughness and abrasion resistance of the present invention. . This may be because, unlike the structure of hydroxy acrylate, fluorine-substituted acrylate fluorine has high electronegativity, and has a strong binding ability to electron clouds, which is beneficial to the formation of hydrogen bonds with the amino and hydroxyl groups of PUA, thereby increasing The polymerization efficiency of fluorine-substituted acrylate, and by controlling the temperature, the molecular weight and viscosity of the final prepolymer can be controlled to ensure the balance of toughness and hardness, and the hydrogen bond forms physical cross-linking points, which is conducive to the hardness and toughness. Increase, and the presence of fluorine atoms is conducive to increase the contact angle, reduce surface energy, thereby increasing wear resistance. In addition, due to the large steric hindrance of fluorine atoms, the polymerization rate of fluorine-substituted acrylates is slow, which is also conducive to the copolymerization of fluorine-substituted acrylates and hydroxy acrylates to form a structure with alternating fluorine substituents and hydroxyl substituents. It is easier to form hydrogen bonds, which is also conducive to the improvement of toughness and hardness. The prepolymer formed by the present invention has a molecular weight of 3000-5000 and a viscosity of 180-300 cps, and through the combined action of the prepolymer and active monomers of the present invention, the prepared hard coating liquid can be applied to flexible cover plates. It can be coated on transparent polyimide, and cured by ultraviolet light to form a hard coating liquid. It has high optical transmittance and mechanical properties. It has strong adhesion to transparent polyimide and is resistant to Repeated bending, with good toughness, hardness and wear resistance.

The molecular weight is the sum of the relative atomic mass of each atom in the chemical formula. The molecular weight in the present invention is obtained by testing according to a method well known to those skilled in the art, and is not further limited.

Viscosity refers to the measurement of the internal friction force generated between molecules when the liquid moves under the action of external force, and represents the flow resistance of the liquid itself. The viscosity of the present invention is measured according to a method well known to those skilled in the art, and is not further limited.

The applicant found that when the number of fluorine substitutions in the fluorine-substituted acrylate is large, due to the larger group and polarity of fluorine, the movement of the chain segment will be hindered, thereby reducing the toughness, and as the number of fluorine substitutions increases, The compatibility with the polyester segment and the acrylate segment is reduced, which is likely to cause defects, thereby reducing toughness and hardness.

Active monomer

In one embodiment, the reactive monomer of the present invention includes a high-functionality acrylate, and the functionality of the high-functionality acrylate is 10-15; further, the functionality of the high-functionality acrylate of the present invention is The degree is 15; further, the high-functionality acrylate of the present invention is purchased from Shenzhen Keda Science and Technology New Materials Co., Ltd., and the brand is UV9600.

The functionality of the high-functionality acrylate of the UV9600 is 15.

Preferably, the reactive monomer of the present invention also includes acrylic silicone oil, and the weight ratio of the high-functionality acrylate to acrylic silicone oil is (3～4):(3～4); further, the high-functionality acrylate of the present invention The weight ratio of acrylic ester and acrylic silicone oil is 1:1.

The acrylic silicone oil of the present invention is an organosilicon diacrylate, which contains a siloxane main chain and two acrylate side chains. It can be used as a reactive monomer and prepolymer to participate in the curing reaction to form a cross-linked high Molecular system.

More preferably, the acrylic silicone oil of the present invention is purchased from allnex, and the brand name is EBECRYL 350.

The applicant found that by adding active monomers, especially high-functionality acrylates as active monomers, it is beneficial to increase the hardness, but the toughness will be greatly reduced. This is mainly because the addition of high-functionality active monomers leads to cross-linking The density of the network increases rapidly, and the excessive viscosity of the high-functionality acrylate can also easily cause uneven dispersion, thereby significantly reducing the toughness. However, the applicant found that when acrylic silicone oil and high-functionality acrylate work together, As a reactive monomer, it can increase the hardness while preventing the decrease in toughness. This may be because when acrylic silicone oil, high-functional acrylate and prepolymer work together, it can improve the viscosity of high-functional acrylate. Promote the uniform dispersion of high-functionality acrylates, and due to the presence of double bonds in the acrylic silicone oil, the acrylic silicone oil reacts with the prepolymer, thereby embedding the silicone oil chain on the main chain of the prepolymer, due to the substitution of fluorine in the silicone oil and the prepolymer The joint action of the base can make the contact angle greater than 107 and reduce the surface energy, thereby increasing the hardness. In addition, during the curing stage, the high-functionality acrylate is uniformly dispersed around the prepolymer along with the silicone oil, making the high-functionality acrylate and When the prepolymer is polymerized, it will also polymerize with the double bonds in the acrylic silicone oil to form a prepolymer-high-functionality acrylate-silicone oil triblock system. The crosslinking density is controlled in an appropriate range, and the hardness is improved at the same time. It is also conducive to the maintenance of toughness.

In one embodiment, the raw materials for preparing the hard coating liquid of the present invention further include modified nanoparticles, and the weight ratio of the modified nanoparticles to the active monomer is 1: (1.5-2.5).

In a more preferred embodiment, the weight ratio of the modified nanoparticles and active monomers of the present invention is 1:2.

Modified nanoparticles

In one embodiment, the modified nanoparticles of the present invention are selected from one of modified nano silicon carbide, modified nano zirconium dioxide or modified nano boron nitride; further, the modified nano particles of the present invention The nano particles are modified nano silicon carbide.

Silicon carbide (SiC) is a kind of non-oxide material with excellent performance. It has the advantages of high hardness, high elastic modulus, heat resistance, wear resistance and corrosion resistance. It has a wide range of applications in aerospace, electronics, chemical and other fields. Many scholars at home and abroad are actively working on the application of SiC. However, due to the small particle size and high surface energy of ultrafine powders, especially nano-sized powders, it is easy to agglomerate to form secondary particles, so that surface area effects, volume effects, and quantum size effects cannot be exhibited. It is difficult to achieve uniform dispersion between particles of different phases in the nanoscale range and compatibility with the matrix during sintering and forming, which in turn affects the improvement of composite material performance. Therefore, it is necessary to modify the surface of silicon carbide to obtain modified silicon carbide to prevent agglomeration and improve compatibility with the matrix.

Surface modification methods of modified silicon carbide include surface physical modification and surface chemical modification. The physical modification of the surface relies on physical methods or van der Waals force connection modification methods. According to the difference of the process, methods such as electroless plating, electroplating, vapor deposition, sol-gel, radiation and mechanical coating can be cited. The modifiers used for surface physical modification mainly include surfactants, hyperdispersants, and inorganic substances. Surface chemical modification is accomplished by chemical reaction or chemical adsorption between the surface modifier and the silicon carbide surface. The surface modifiers for surface chemical modification include coupling agents, higher fatty acids and their salts, and unsaturated Organic acids and silicones, etc. The present invention does not limit the specific modification method of modified silicon carbide, and the modified silicon carbide can be purchased or self-made. The particle size of the modified nano silicon carbide of the present invention is 4-60 nm.

Preferably, the modified nano silicon carbide of the present invention is purchased from Carbodeon Ltd Oy, and the brand is 5007.

Silicon carbide has high hardness and wear resistance, but the incompatibility between silicon carbide and the base material easily causes silicon carbide to fall out during multiple bendings, thereby affecting toughness, cracking or whitening. However, the applicant found that, Adding fluorine-substituted acrylate to the prepolymer preparation raw materials makes the cross-linking system contain highly electronegative fluorine substituents, which is conducive to physical adsorption with the silicon carbide surface and prevents silicon carbide from falling out during multiple bending processes In addition, the high-functionality acrylate added to the active monomer contains more double bonds. During the curing process, some double bonds will not participate in the reaction, and the remaining polar double bonds will also increase the effect of silicon carbide Through the action of the fluorine substitute agent and the residual double bond, the silicon carbide is not easy to fall out during the multiple bending process, so that the silicon carbide can effectively increase the hardness and wear resistance of the CIP without affecting the toughness. . In addition, the applicant found that when the fluorine-substituted acrylate is not added in the preparation of the prepolymer, or the light energy of the high-functional acrylate is too low, the modified nanoparticles are easy to fall out during multiple bending processes, thereby Causes bleaching, bubbles and other phenomena, which reduces toughness.

Photoinitiator

Photoinitiators are compounds that can absorb a certain wavelength of energy in the ultraviolet light region (250-420nm) or visible light region (400-800nm), generate free radicals, cations, etc., thereby initiating monomer polymerization, crosslinking and curing. The present invention does not specifically limit the photoinitiator. Examples include 2959 photoinitiator, 184 photoinitiator, 1173 photoinitiator, 907 photoinitiator, TPO photoinitiator, TPO-L photoinitiator, IHT-PI 910 photoinitiator, 659 photoinitiator, MBF photoinitiator, IHT-PI 4265 photoinitiator, IHT-PI 1000 photoinitiator, IHT-PI 500 photoinitiator.

In one embodiment, the photoinitiator of the present invention includes 2959 photoinitiator and 184 photoinitiator, and the weight ratio is (5-8): (2-5); further, the 2959 photoinitiator of the present invention And 184 photoinitiator, the weight ratio is 7:3.

Solvent

The present invention does not specifically limit the solvent. Examples include propylene glycol monomethyl ether, propylene glycol methyl ether acetate, 2-propanol, n-butyl acetate, butanone, and methyl isobutyl ketone.

In one embodiment, the solvent of the present invention is propylene glycol monomethyl ether.

The second aspect of the present invention provides the above-mentioned preparation method of the hardened coating liquid for the flexible cover plate, which includes the following steps:

The preparation raw materials of the hard coating liquid are mixed to obtain the hard coating liquid.

The hardened coating solution prepared by the present invention can be applied to flexible cover plates, has high optical transmittance, and can significantly increase wear resistance and hardness while ensuring the high toughness of the flexible cover plates, especially for hardening coatings. The layer liquid is coated on the transparent polyimide film, such as by micro-gravure coating, etc., on the transparent polyimide film, and cured by ultraviolet light to prepare a hardened coating. The thickness of the coating can be 5～ 10μm.

Example

The present invention will be described in detail through the following examples. It is necessary to point out that the following examples are only used to further illustrate the present invention, and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements made by professionals in this field based on the above-mentioned content of the present invention And adjustments still belong to the protection scope of the present invention.

Example 1

Embodiment 1 of the present invention provides a hardened coating solution for flexible cover plates. The preparation raw materials of the hardened coating solution are based on parts by weight, including 50 parts of prepolymer, 1.4 parts of active monomer, and 0.9 parts of modified. Nano silicon carbide, 1 part photoinitiator, 40 parts propylene glycol monomethyl ether; the active monomer includes high-functionality acrylate and acrylic silicone oil, and the weight ratio is 3:4.

The preparation method of the prepolymer includes the following steps:

Pretreatment: Add isophorone diisocyanate and dibutyl tin dilaurate to acetone and mix to obtain an isophorone diisocyanate solution;

Synthesis of hyperbranched polyurethane: add the hydroxyl-terminated hyperbranched polyester dropwise to the isophorone diisocyanate solution at 45°C and keep it warm for 1 hour to obtain a hyperbranched polyurethane mixture;

Prepolymer synthesis: heat the hyperbranched polyurethane mixture to 65°C, add hydroxy acrylate dropwise, cool to 35°C, add trifluoroethyl methacrylate, and keep it for 2 hours to obtain a prepolymer;

The weight ratio of the hydroxyl-terminated hyperbranched polyester, isophorone diisocyanate and hydroxy acrylate is 2.5:1:1.5, and the dibutyltin dilaurate accounts for 0.6 wt% of the isophorone diisocyanate, The hydroxy acrylate includes difunctional hydroxy acrylate and pentaerythritol triacrylate in a weight ratio of 1:0.5, and the difunctional hydroxy acrylate includes 2-hydroxyethyl acrylate and 3-hydroxy-1-adamantyl The weight ratio of methacrylate is 1:0.4, and the weight ratio of trifluoroethyl methacrylate and hydroxyacrylate is 1:20.

The hydroxyl-terminated hyperbranched polyester was purchased from Pertorp, Sweden, under the brand name Boltorn H20.

The high-functionality acrylate was purchased from Shenzhen Keda Science and Technology New Materials Co., Ltd., the brand was UV9600, and the functionality was 15.

The acrylic silicone oil was purchased from allnex, and the brand was EBECRYL 350.

The modified nano silicon carbide was purchased from Carbodeon Ltd Oy, and the brand was 5007.

The photoinitiator includes 2959 photoinitiator and 184 photoinitiator, and the weight ratio is 5:2.

Example 2

Embodiment 2 of the present invention provides a hardened coating solution for flexible cover plates. The preparation raw materials of the hardened coating solution are based on parts by weight, including 40 parts of prepolymer, 0.8 parts of active monomer, and 0.35 parts of modification. Nano silicon carbide, 0.5 parts photoinitiator, 30 parts propylene glycol monomethyl ether; the active monomer includes high-functionality acrylate and acrylic silicone oil, and the weight ratio is 4:3.

The preparation method of the prepolymer includes the following steps:

Pretreatment: Add isophorone diisocyanate and dibutyl tin dilaurate to acetone and mix to obtain an isophorone diisocyanate solution;

Synthesis of hyperbranched polyurethane: add the hydroxyl-terminated hyperbranched polyester dropwise to the isophorone diisocyanate solution at 45°C and keep it for 1 hour to obtain a hyperbranched polyurethane mixture;

Prepolymer synthesis: heat the hyperbranched polyurethane mixture to 65°C, add hydroxy acrylate dropwise, cool to 35°C, add trifluoroethyl methacrylate, and keep it for 2 hours to obtain a prepolymer;

The weight ratio of the hydroxyl-terminated hyperbranched polyester, isophorone diisocyanate and hydroxy acrylate is 1.5:1:1, and the dibutyltin dilaurate accounts for 0.4wt% of the isophorone diisocyanate, The hydroxy acrylate includes difunctional hydroxy acrylate and pentaerythritol triacrylate in a weight ratio of 1:0.3, and the difunctional hydroxy acrylate includes 2-hydroxyethyl acrylate and 3-hydroxy-1-adamantyl The weight ratio of methacrylate is 1:0.3, and the weight ratio of trifluoroethyl methacrylate and hydroxyacrylate is 1:10.

The hydroxyl-terminated hyperbranched polyester was purchased from Pertorp, Sweden, under the brand name Boltorn H20.

The high-functionality acrylate was purchased from Shenzhen Keda Science and Technology New Materials Co., Ltd., the brand was UV9600, and the functionality was 15.

The acrylic silicone oil was purchased from allnex, and the brand was EBECRYL 350.

The modified nano silicon carbide was purchased from Carbodeon Ltd Oy, and the brand was 5007.

The photoinitiator includes 2959 photoinitiator and 184 photoinitiator, and the weight ratio is 4:1.

Example 3

Embodiment 3 of the present invention provides a hardened coating solution for flexible cover plates. The preparation raw materials of the hardened coating solution are based on parts by weight, including 40 parts of prepolymer, 1 part of active monomer, and 0.5 parts of modified material. Nano silicon carbide, 1 part of photoinitiator and 30 parts of propylene glycol monomethyl ether, the active monomers include high-functionality acrylate and acrylic silicone oil, and the weight ratio is 1:1.

The preparation method of the prepolymer includes the following steps:

Pretreatment: Add isophorone diisocyanate and dibutyl tin dilaurate to acetone and mix to obtain an isophorone diisocyanate solution;

Synthesis of hyperbranched polyurethane: add the hydroxyl-terminated hyperbranched polyester dropwise to the isophorone diisocyanate solution at 45°C and keep it warm for 1 hour to obtain a hyperbranched polyurethane mixture;

Prepolymer synthesis: heat the hyperbranched polyurethane mixture to 65°C, add hydroxy acrylate dropwise, cool to 35°C, add trifluoroethyl methacrylate, and keep it for 2 hours to obtain a prepolymer;

The weight ratio of the hydroxyl-terminated hyperbranched polyester, isocyanate, and hydroxyacrylate is 2:1:1.3, the dibutyltin dilaurate accounts for 0.5wt% of the isophorone diisocyanate, and the hydroxyacrylate It includes difunctional hydroxy acrylate and pentaerythritol triacrylate in a weight ratio of 1:0.4. The difunctional hydroxy acrylate includes 2-hydroxyethyl acrylate and 3-hydroxy-1-adamantyl methacrylate. The weight ratio of ester is 1:0.3, and the weight ratio of trifluoroethyl methacrylate and hydroxyacrylate is 1:10.

The hydroxyl-terminated hyperbranched polyester was purchased from Pertorp, Sweden, under the brand name Boltorn H20.

The high-functionality acrylate was purchased from Shenzhen Keda Science and Technology New Materials Co., Ltd., the brand was UV9600, and the functionality was 15.

The acrylic silicone oil was purchased from allnex, and the brand was EBECRYL 350.

The modified nano silicon carbide was purchased from Carbodeon Ltd Oy, and the brand was 5007.

The photoinitiator includes 2959 photoinitiator and 184 photoinitiator, and the weight ratio is 7:3.

Example 4

Embodiment 4 of the present invention provides a hardened coating solution for flexible cover plates. The preparation raw materials of the hardened coating solution are based on parts by weight, including 40 parts of prepolymer, 1 part of active monomer, and 1 part of light. Initiator and 30 parts of propylene glycol monomethyl ether, the active monomer includes high-functionality acrylate and acrylic silicone oil, and the weight ratio is 1:1.

The preparation method of the prepolymer includes the following steps:

Pretreatment: Add isophorone diisocyanate and dibutyl tin dilaurate to acetone and mix to obtain an isophorone diisocyanate solution;

Synthesis of hyperbranched polyurethane: add the hydroxyl-terminated hyperbranched polyester dropwise to the isophorone diisocyanate solution at 45°C and keep it warm for 1 hour to obtain a hyperbranched polyurethane mixture;

Prepolymer synthesis: heat the hyperbranched polyurethane mixture to 65°C, add hydroxy acrylate dropwise, cool to 35°C, add trifluoroethyl methacrylate, and keep it for 2 hours to obtain a prepolymer;

The weight ratio of the hydroxyl-terminated hyperbranched polyester, isocyanate, and hydroxyacrylate is 2:1:1.3, the dibutyltin dilaurate accounts for 0.5wt% of the isophorone diisocyanate, and the hydroxyacrylate It includes difunctional hydroxy acrylate and pentaerythritol triacrylate in a weight ratio of 1:0.4. The difunctional hydroxy acrylate includes 2-hydroxyethyl acrylate and 3-hydroxy-1-adamantyl methacrylate. The weight ratio of ester is 1:0.3, and the weight ratio of trifluoroethyl methacrylate and hydroxyacrylate is 1:10.

The hydroxyl-terminated hyperbranched polyester was purchased from Pertorp, Sweden, under the brand name Boltorn H20.

The high-functionality acrylate was purchased from Shenzhen Keda Science and Technology New Materials Co., Ltd., the brand was UV9600, and the functionality was 15.

The acrylic silicone oil was purchased from allnex, and the brand was EBECRYL 350.

The photoinitiator includes 2959 photoinitiator and 184 photoinitiator, and the weight ratio is 7:3.

Comparative example 1

Comparative Example 1 of the present invention provides a hardened coating liquid for flexible cover plates. The specific implementation is the same as that of Example 3. The difference is that the difunctional hydroxy acrylate does not include 3-hydroxy-1- Adamantyl methacrylate.

Comparative example 2

Comparative Example 2 of the present invention provides a hardened coating solution for flexible cover plates. The specific implementation is the same as that of Example 3, except that the 2-hydroxyethyl acrylate is replaced with 4-hydroxybutyl. Base acrylate.

Comparative example 3

Comparative Example 3 of the present invention provides a hard coating liquid for flexible cover plates. The specific implementation is the same as that of Example 3, except that the hydroxy acrylate does not include tetrafunctional hydroxy acrylate.

Comparative example 4

Comparative Example 4 of the present invention provides a hardened coating liquid for flexible cover plates. The specific implementation is the same as that of Example 3, except that the weight ratio of the difunctional hydroxy acrylate and the tetrafunctional hydroxy acrylate is It is 1:1.

Comparative example 5

Comparative Example 5 of the present invention provides a hardened coating solution for flexible cover plates. The specific implementation is the same as that of Example 3. The difference is that in the preparation method of the prepolymer, methacrylic acid is not added. Trifluoroethyl acid.

Comparative example 6

Comparative Example 6 of the present invention provides a hardened coating liquid for flexible cover plates. The specific implementation is the same as that of Example 3, except that the weight ratio of the trifluoroethyl methacrylate and the hydroxy acrylate is It is 1:2.

Comparative example 7

Comparative Example 7 of the present invention provides a hardened coating solution for flexible cover plates. The specific implementation is the same as that of Example 3, except that the trifluoroethyl methacrylate is replaced with twelve methacrylate. Fluoroheptyl ester.

Comparative example 8

Comparative Example 8 of the present invention provides a hardened coating liquid for flexible cover plates. The specific implementation is the same as that of Example 3, except that the preparation method of the prepolymer includes the following steps:

Pretreatment: Add isophorone diisocyanate and dibutyl tin dilaurate to acetone and mix to obtain an isophorone diisocyanate solution;

Synthesis of hyperbranched polyurethane: dissolve the hydroxyl-terminated hyperbranched polyester in acetone, and add it dropwise to the isophorone diisocyanate solution at 45°C for 1 hour to obtain a hyperbranched polyurethane mixture;

Prepolymer synthesis: the hyperbranched polyurethane mixture is heated to 65°C, hydroxyacrylate is added dropwise, and the temperature is lowered to 65°C, trifluoroethyl methacrylate is added, and the temperature is maintained for 0.5h to obtain a prepolymer.

Comparative example 9

Comparative Example 9 of the present invention provides a hardened coating solution for flexible cover plates. The specific implementation is the same as that of Example 3, except that the high-functionality acrylate is replaced with dipentaerythritol pentaacrylate.

Comparative example 10

Comparative Example 10 of the present invention provides a hardened coating liquid for flexible cover plates. The specific implementation is the same as that of Example 3, except that the acrylic silicone oil is replaced with tripropylene glycol diacrylate.

Comparative example 11

Comparative Example 11 of the present invention provides a hard coating liquid for flexible cover plates. The specific implementation is the same as that of Example 3, except that the weight ratio of the high-functionality acrylate to the acrylic silicone oil is 1: 0.2.

Examples 1 to 4 and Comparative Examples 1 to 11 also provide a preparation method of a hardened coating solution for a flexible cover plate, which includes the following steps:

The preparation raw materials of the hard coating liquid are mixed to obtain the hard coating liquid.

Performance evaluation

1. Hardness test: The hardened coating liquids provided in Examples 1 to 4 and Comparative Examples 1 to 11 were coated on a transparent polyimide film and cured by ultraviolet light to test the pencil hardness. The results are shown in Table 1.

2. Toughness test: The hardened coating liquids provided in Examples 1 to 4 and Comparative Examples 1 to 11 were subjected to dynamic bending and static bending tests. The specific test methods are as follows:

(1) Dynamic bending: Coat the hardened coating liquids provided in Examples 1 to 4 and Comparative Examples 1 to 11 on a transparent polyimide film, and after curing with UV light, observe the dynamic bending with a Yuasa bending tester. Folding R = 2mm 180 ° bending 150 thousand times, 200,000 times and 250,000 times whether there is peeling, cracking, whitening, bubbles, and turning over. Among them, O means no peeling, cracking, whitening, bubbles, and turning phenomena, X For the phenomenon of peeling, cracking, whitening, bubbles, and turning over, the results are shown in Table 1.

(2) Static bending: Coat the hardened coating liquid provided in Examples 1 to 3 on the transparent polyimide film, and after curing by UV light, observe the static bending (outside folding R4/ Inward bend R2, test environment 60°C, 90% humidity, and stand for 240hrs for cracks and whitening. It is found that the hardened coating solutions provided in Examples 1 to 3 have no cracks or whitening.

3. Abrasion resistance: The hardened coating liquids provided in Examples 1 to 4 and Comparative Examples 1 to 11 were coated on a transparent polyimide film, and after curing with ultraviolet light, a steel wool test was carried out (Bonstar 0000#, 1kgf, 2*2cm2, 40mm) test, observe 5000 times, 6000 times, 7000 times, 8000 times whether there are scratches, where O means scratches and X means no scratches. The results are shown in Table 1.

4. Performance test: The hard coating liquid provided in Examples 1 to 3 was tested for overall light transmittance, HC breaking elongation, initial water drop angle and eraser. The results are shown in Table 2. It is found that the hard coating liquid of the present invention Meet the specification requirements of hard coating liquid for flexible cover plate.

Table 1 Performance Characterization Test

Table 2 Performance Characterization Test

It can be seen from the test results of Table 1 and Table 2 that the hardened coating liquid provided by the present invention has high toughness, high hardness and wear resistance, and no peeling, cracking, whitening, and bleaching after dynamic bending more than 200,000 times. Bubbles, folding, static bending (external bending R4/inward bending R2, test environment 60℃, 90% humidity, standing for 240hrs), no cracks or whitening, and its pencil hardness reaches more than 8H, after 8000 times of steel wool The test has no scratches and can be used for flexible cover plates as the hardened layer of flexible cover plates, with high light transmittance and elongation at break.

The foregoing examples are only illustrative, and are used to explain some features of the method of the present invention. The appended claims are intended to require the widest possible scope conceivable, and the embodiments presented herein are only descriptions of selected implementations based on combinations of all possible embodiments. Therefore, the applicant's intention is that the appended claims are not limited by the selection of examples illustrating the characteristics of the present invention. Some numerical ranges used in the claims also include sub-ranges within them, and changes in these ranges should also be interpreted as being covered by the appended claims when possible.

Claims (10)

A hardened coating liquid for a flexible cover plate, characterized in that the preparation raw materials of the hardened coating liquid include 40-50 parts by weight of prepolymer, 0.8-1.4 parts of active monomer, 0.5-1.4 parts by weight. 1 part photoinitiator and 30-40 parts solvent. The hardened coating liquid for flexible cover plates according to claim 1, wherein the preparation method of the prepolymer comprises the following steps: Pretreatment: Add isocyanate and catalyst to the solvent and mix to obtain isocyanate solution; Synthesis of hyperbranched polyurethane: Add the hydroxyl-terminated hyperbranched polyester dropwise to the isocyanate solution at 40～50℃, keep it for 0.5～2h to obtain the hyperbranched polyurethane mixture; Prepolymer synthesis: The hyperbranched polyurethane mixture is heated to 60-70°C, hydroxy acrylate is added dropwise, and the temperature is lowered to 30-40°C, fluorine-substituted acrylate is added, and the temperature is maintained for 1.5-2.5 hours to obtain a prepolymer. The hardened coating liquid for flexible cover plates according to claim 2, wherein the weight ratio of the hydroxyl-terminated hyperbranched polyester, isocyanate and hydroxyacrylate is (1.5~2.5):1:(1 ~1.5). The hardened coating liquid for flexible cover plates according to claim 2, wherein the isocyanate is an alicyclic diisocyanate and/or an aliphatic diisocyanate. The hardened coating liquid for flexible cover plates according to claim 2, wherein the hydroxy acrylate comprises a difunctional hydroxy acrylate and a tetrafunctional hydroxy acrylate, and the weight ratio is 1: (0.3~ 0.5). The hardened coating liquid for flexible cover plates according to claim 2, wherein the number of fluorine substitutions in the fluorine-substituted acrylate is 3-6. The hardened coating liquid for flexible cover plates according to any one of claims 1 to 6, wherein the reactive monomer comprises a high-functionality acrylate, and the functionality of the high-functionality acrylate is 10-15. The hardened coating liquid for flexible cover plates according to claim 7, wherein the reactive monomer further comprises acrylic silicone oil, and the weight ratio of the high-functionality acrylate to acrylic silicone oil is (3～4 ): (3～4). The hardened coating liquid for flexible cover plates according to claim 1, wherein the preparation raw material of the hardened coating liquid further comprises modified nanoparticles, the weight of the modified nanoparticles and the active monomer The ratio is 1: (1.5～2.5). A method for preparing a hardened coating liquid for a flexible cover plate according to any one of claims 1-9, characterized in that it comprises the following steps: The preparation raw materials of the hard coating liquid are mixed to obtain the hard coating liquid.