WO2018056710A1 - Optical transparent adhesive composition, optical transparent adhesive film comprising same, and flat panel display device - Google Patents

Abstract

The present invention provides an optical transparent adhesive composition, an optical transparent adhesive film comprising the same, and a flat panel display device, the optical transparent adhesive composition comprising a photo-curable (meth)acrylate copolymer, a polydimethylsiloxane-based (meth)acrylate compound, and a photo-polymerization initiator, wherein the photo-curable (meth)acrylate copolymer comprises, relative to the total weight of constituent units contained in the copolymer, 95-99.9 wt% of a hydroxy group-containing acryl-based copolymer and 0.1-5 wt% of an isocyanate group-containing (meth)acrylate-based monomer and the hydroxy group-containing acryl-based copolymer and the isocyanate group-containing (meth)acrylate-based monomer form a urethane bond, and wherein the hydroxy group-containing acryl-based copolymer comprises, relative to the total weight of monomers contained in the copolymer, 50-98 wt% of a C₁-C₁₂ linear or branched chain alkyl (meth)acrylate monomer and 2-50 wt% of a hydroxy group-containing polymerizable monomer and the weight average molecular weight of the hydroxy group-containing acryl-based copolymer is 200,000 to 1,000,000.

Description

Optical transparent adhesive composition, Optical transparent adhesive film and flat panel display device containing same

The present application relates to an optically transparent adhesive composition, an optically transparent adhesive film and a flat panel display device including the same.

The flat panel display includes a liquid crystal display (LCD), a plasma display panel (PDP), an organic electroluminescent display (OLED), and the like.

Such a flat panel display includes a display panel and an optical film. As said optical film, a polarizing film, a retardation film, an anti-glare film, a wide viewing angle compensation film, a brightness improving film, etc. are used. When these optical films are laminated to each other or the optical film is attached to the display panel, an optical transparent adhesive (OCA) is used. Therefore, optically clear adhesive (OCA) should basically have excellent moisture resistance, heat resistance and adhesion with optical properties.

In particular, recently, flexible display devices have been competitively developed. Since the flexible display apparatus is bent, rolled, or folded, the display panel and the optical films included in the apparatus are also subjected to bending stress. Therefore, optically transparent adhesives (OCAs) used in flexible displays require more enhanced and diversified physical properties.

For example, an optically clear adhesive (OCA) used in a flexible display device should have excellent folding properties to enable flexible folding of the device. In particular, when considering the case of using the flexible display device for a long time in the low temperature state, the folding characteristics at low temperature should be excellent.

In addition, an optically transparent adhesive (OCA) used in a flexible display device requires more enhanced heat and moisture resistance. Because the flexible display device repeats the folding and unfolding process during use, the likelihood of penetration of moisture through the folded and unfolded portion increases.

In addition, as the flexible display device is bent, rolled, or folded, display panels and optical films included in the device are also subjected to bending stress. Therefore, it is easy to be separated between the stacked display panel and the optical film is required for better adhesion, more excellent durability is also required.

However, the optically transparent adhesives (OCAs) known to date do not sufficiently provide the above properties required by the flexible display device.

[Preceding technical literature]

[Patent Documents]

(Patent Document 1) Republic of Korea Patent Publication No. 10-2016-0085759

The present invention has been made to solve the above problems of the prior art, to provide an optical transparent pressure-sensitive adhesive (OCA) composition that can sufficiently satisfy the folding properties, moist heat resistance, heat resistance and adhesion required in the flexible display device The purpose.

Another object of the present invention is to provide an optically transparent adhesive film and a flat panel display device including the optically transparent adhesive (OCA) composition.

The present invention

Photocurable (meth) acrylate copolymers; Polydimethylsiloxane-based (meth) acrylate compounds; And a photopolymerization initiator, comprising:

The photocurable (meth) acrylate copolymer includes 95 to 99.9 wt% of a hydroxy group-containing acrylic copolymer and 0.1 to 5 wt% of an isocyanate group-containing (meth) acrylate monomer based on the total weight of structural units included in the copolymer. The hydroxyl group-containing acrylic copolymer and the isocyanate group-containing (meth) acrylate monomer form a urethane bond,

The hydroxy group-containing acrylic copolymer is 50 to 98% by weight of C ₁ ~ C ₁₂ linear or branched alkyl (meth) acrylate monomers and 2 to 50% by weight of hydroxy group-containing polymerizable monomers based on the total weight of monomers in the copolymer. It includes, and provides an optically transparent adhesive composition, characterized in that the weight average molecular weight is 200,000 to 1 million.

In addition, the present invention

It provides an optical transparent pressure-sensitive adhesive film, which is prepared by coating the optical transparent pressure-sensitive adhesive composition of the present invention on a transfer film.

In addition, the present invention

It provides a flat panel display device comprising an adhesive layer formed of the optically transparent adhesive composition of the present invention.

The optically clear adhesive (OCA) composition and the optically clear adhesive film of the present invention provide sufficient folding properties, heat-and-moisture resistance, heat resistance, and adhesion to be used in a flat panel display as well as a flexible display device, thereby providing excellent durability. to provide.

Since the flat panel display device of the present invention is manufactured using the above-described pressure-sensitive adhesive composition, it is possible to provide excellent folding characteristics, heat and humidity resistance, heat resistance, adhesiveness, and excellent durability.

The present invention, photocurable (meth) acrylate copolymer; Polydimethylsiloxane-based (meth) acrylate compounds; And a photopolymerization initiator, comprising:

The photocurable (meth) acrylate copolymer includes 95 to 99.9 wt% of a hydroxy group-containing acrylic copolymer and 0.1 to 5 wt% of an isocyanate group-containing (meth) acrylate monomer based on the total weight of structural units included in the copolymer. The hydroxyl group-containing acrylic copolymer and the isocyanate group-containing (meth) acrylate monomer form a urethane bond,

The hydroxy group-containing acrylic copolymer is 50 to 98% by weight of C ₁ ~ C ₁₂ linear or branched alkyl (meth) acrylate monomers and 2 to 50% by weight of hydroxy group-containing polymerizable monomers based on the total weight of monomers in the copolymer. It includes, and relates to an optically transparent adhesive composition, characterized in that the weight average molecular weight is 200,000 to 1 million.

The optically transparent adhesive composition of the present invention includes a photocurable acrylate copolymer having a polarity and a low Tg polydimethylsiloxane-based (meth) acrylate compound, thereby being excellent in folding property, heat-and-moisture resistance property, and adhesiveness, and photocurability. It is characterized by providing an optically transparent adhesive composition excellent in heat resistance and durability by photocrosslinking between an acrylate copolymer and a low Tg polydimethylsiloxane-based (meth) acrylate compound.

In the present invention, the "(meth) acrylate" means "acrylate" or "methacrylate".

The photocurable (meth) acrylate copolymer copolymerizes a C ₁ to C ₁₂ straight or branched chain alkyl (meth) acrylate monomer and a hydroxy group-containing polymerizable monomer, whereby a thermosetting functional group (hydroxy group) By introducing the introduced hydroxyl group-containing acrylic copolymer main chain, and then reacting the isocyanate group-containing (meth) acrylate monomer with the main chain under appropriate conditions, at least a part of the thermosetting functional group (hydroxy group) of the main chain contains an isocyanate group ( It may be prepared by substitution with a meta) acrylate monomer.

The structure of the photocurable (meth) acrylate copolymer can be illustrated by Formula A:

[Formula A]

In the above formula

R ₁ is a C ₁ to C ₁₂ straight or branched alkyl group,

R ₂ is a C ₁ to C ₁₀ linear or branched alkylene group,

Each R ₃ is independently hydrogen or methyl,

o and p are each independently a natural number of 2 to 6,

1, m, and n each have a value formed according to the range of usage of the monomers described above.

The main chain is, for example, through a conventional polymerization method such as solution polymerization, photo polymerization, bulk polymerization, suspension polymerization or emulsion polymerization. Can be prepared.

As the polydimethylsiloxane-based (meth) acrylate compound, for example, one or more selected from compounds represented by the following Chemical Formulas 1 to 3 may be used:

[Formula 1]

[Formula 2]

[Formula 3]

In Chemical Formulas 1 to 3,

Each R ₁ is independently hydrogen or methyl;

R ₂ is a C ₁ to C ₅ straight or branched alkylene group,

Each R ₃ is independently a group derived from a diisocyanate compound with an —N (H) —C (O) — group bonded to both sides thereof,

R ₄ is a C ₁ to C ₅ straight or branched alkylene group,

P, Q, and R are each independently a natural number of 3 to 100.

Examples of the diisocyanate compounds include HDI (Hexamethylene Diisocyanate), IPDI (Isophorone Diisocyanate), TDI (Toluene Diisocyanate), and the like, but are not limited thereto.

A C ₁ ~ C ₁₂ straight-chain or a branched-chain alkyl (meth) acrylate monomer contained in the polymerization to form the hydroxyl group-containing acrylic copolymer is a C ₁ ~ C glass transition temperature (Tg) of -70 ~ -50 ℃ A straight or branched chain alkyl (meth) acrylate monomer of ₁₂ may be preferably used, more preferably C4 to C12 straight or branched chain alkyl acrylate monomer having a glass transition temperature (Tg) of -70 to -50 ° C. Can be used.

Examples of C ₄ to C ₁₂ straight or branched chain alkyl acrylate monomers having a glass transition temperature (Tg) of -70 to -50 ° C include n-butyl acrylate, t-butyl acrylate, sec-butyl acrylate, Pentyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, isononyl acrylate and the like, and these may be used alone or in combination of two or more thereof. Can be used. Of these, n-butyl acrylate and 2-ethylhexyl acrylate can be preferably used.

When the glass transition temperature (Tg) of the C ₁ ~ C ₁₂ linear or branched alkyl acrylate monomer is -70 ° C, it is difficult to use it because of economic efficiency, and when it exceeds -50 ° C, the folding property at low temperature is The problem of deterioration arises.

As the hydroxy group-containing polymerizable monomer included in a polymerized form in the hydroxy group-containing acrylic copolymer, a monomer having one hydroxy group and one ethylenically unsaturated bond in a molecule may be preferably used. In addition, more preferably, a hydroxy group-containing acrylate monomer having a glass transition temperature (Tg) of -60 to -40 ° C may be used.

The glass transition temperature (Tg) is -60 ~ As the hydroxyl group-containing acrylate monomer at -40 ° C, a hydroxy C ₄ to C ₆ straight or branched chain alkyl acrylate monomer may be preferably used.

Examples of the hydroxy C ₄ to C ₆ linear or branched alkyl acrylate monomers include 4-hydroxybutyl acrylate, 5-hydroxypentyl acrylate, 6-hydroxyhexyl acrylate, and the like. It may be used alone or in combination of two or more. Of these, 4-hydroxybutyl acrylate can be preferably used.

The monomer having a glass transition temperature (Tg) of the hydroxyl group-containing acrylate monomer in the above is less than -60 ℃, it is difficult to exist, when the temperature exceeds -40 ℃ may cause a problem that the folding properties at low temperatures.

In the hydroxy group-containing acrylic copolymer, C ₁ ~ C ₁₂ linear or branched alkyl (meth) acrylate monomers are contained in 50 to 98% by weight, hydroxy group-containing polymerizable monomer may be included in 2 to 50% by weight. have.

More preferably, the C ₁ ~ C ₁₂ linear or branched alkyl (meth) acrylate monomer is included in 50 to 89% by weight, hydroxy group-containing polymerizable monomer may be included in 11 to 50% by weight.

In the case where the hydroxyl group-containing polymerizable monomer is included in less than 11% by weight, the hydroxy group which is a hydrophilic group is insufficient in the pressure-sensitive adhesive, the moisture is released from the pressure-sensitive adhesive layer and the moisture is discharged to the interface, resulting in poor adhesion due to damp-heat-resistant conditions. This may occur, when included in excess of 50% by weight, the pressure-sensitive adhesive absorbs excess moisture, expands the volume, and decreases cohesion, which may cause problems such as interfacial peeling and bubbles.

The hydroxy group-containing acrylic copolymer may further include other copolymerizable monomers known in the art in a polymerized form. The kind of the other copolymerizable monomer is not particularly limited, and examples thereof include (meth) acrylonitrile, (meth) acrylamide, N-methyl (meth) acrylamide or N-butoxy methyl (meth) acrylamide. Such nitrogen-containing monomers; Styrene-based monomers such as styrene or methyl styrene; Glycidyl (meth) acrylate; Or vinyl esters of carboxylic acids such as vinyl acetate, but are not limited thereto.

When the other copolymerizable monomer is included, in consideration of flexibility and peeling force, etc., the content thereof is preferably adjusted to 20 parts by weight or less based on 100 parts by weight of the total monomers described above.

In the hydroxy group-containing acrylic copolymer, the weight average molecular weight means a converted value with respect to standard polystyrene measured by gel permeation chromatograph (GPC).

Isocyanate C ₁ to C ₁₀ straight or branched chain alkyl (meth) acrylates may be used as the isocyanate group-containing (meth) acrylate monomers included in the photocurable (meth) acrylate copolymer. In the above, the C ₁ ~ C ₁₀ linear or branched alkyl group may be methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, Nonyl, decanyl, etc. are mentioned, Among these, ethyl, propyl, etc. can be used preferably.

The isocyanate group-containing (meth) acrylate-based monomer may be included in an amount of 0.1 parts by weight to 5.0% by weight based on the total weight of the structural units included in the photocurable (meth) acrylate copolymer. When the isocyanate group-containing (meth) acrylate-based monomer is included in less than 0.1% by weight, the cohesive force and heat resistance of the pressure-sensitive adhesive composition may be lowered, and when it exceeds 5.0% by weight, the cohesive force of the pressure-sensitive adhesive becomes too strong This can be degraded.

The polydimethylsiloxane-based (meth) acrylate compound included in the optically transparent adhesive composition of the present invention is 10 to 50 parts by weight, more preferably 15 to 30 parts by weight based on 100 parts by weight of the photocurable (meth) acrylate copolymer. It can be included as a wealth. When the polydimethylsiloxane-based (meth) acrylate compound is included in less than 10 parts by weight, it is difficult to secure the low-temperature folding characteristics, when containing more than 50 parts by weight it is difficult to secure the adhesive force to cause a problem that the heat resistance is lowered Can be.

The optically transparent adhesive composition of this invention contains a photoinitiator in order to induce reaction of a radically polymerizable group efficiently. The photopolymerization initiator may be used in the polymerization of the hydroxyl group-containing acrylic copolymer, and finally included in the optically transparent adhesive composition together with the photocurable (meth) acrylate copolymer.

The photopolymerization initiator is not particularly limited and photopolymerization initiators known in the art may be used. Specifically, general initiators such as benzoin initiators, hydroxyketone initiators, amino ketone initiators or phosphine oxide initiators can be used to generate radicals by irradiation with ultraviolet rays to initiate photopolymerization.

When the content of the photopolymerization initiator is too small, the effect of the addition may be insignificant, and when too large, it may adversely affect physical properties such as durability and transparency, so that an appropriate content range may be selected in consideration of this point. .

The photopolymerization initiator may be included in an amount of 0.1 to 5 parts by weight, more preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the photocurable (meth) acrylate copolymer.

The optically transparent adhesive composition of this invention may further contain a polyfunctional crosslinking agent. Such a multifunctional crosslinking agent is not particularly limited, and those known in the art may be used. Specifically, a thermosetting polyfunctional isocyanate crosslinking agent, a polyfunctional (meth) acrylate crosslinking agent, etc. are mentioned.

The multifunctional crosslinking agent may be further included in an amount of 0.02 to 5 parts by weight based on 100 parts by weight of the photocurable (meth) acrylate copolymer.

The optically transparent adhesive composition of this invention may further contain a silane coupling agent. The kind of coupling agent is not particularly limited, and a coupling agent commonly known in the art of adhesive production can be used. For example, as a silane coupling agent, gamma-glycidoxypropyl triethoxy silane, gamma-glycidoxypropyl trimethoxy silane, gamma-glycidoxypropyl methyldiethoxy silane, gamma-glycidoxypropyl triethoxy Silane, 3-mercaptopropyl trimethoxy silane, vinyltrimethoxysilane, vinyltriethoxy silane, gamma-methacryloxypropyl trimethoxy silane, gamma-methacryloxy propyl triethoxy silane, gamma-aminopropyl Trimethoxy silane, gamma-aminopropyl triethoxy silane, 3-isocyanatopropyl triethoxy silane, etc. are mentioned.

The silane coupling agent may be included in an amount of 0.01 to 5 parts by weight, preferably 0.01 to 1 part by weight, based on 100 parts by weight of the photocurable (meth) acrylate copolymer.

The optically transparent adhesive composition of this invention may further contain a tackifier for control of adhesive performance.

It may further comprise one or more additives selected from the group consisting of epoxy resins, curing agents, ultraviolet stabilizers, antioxidants, colorants, reinforcing agents, fillers, antifoaming agents, surfactants and plasticizers.

The optically transparent adhesive composition of this invention may further contain a solvent. As the solvent, any solvent known in the art may be used without limitation as long as it can dissolve monomers and copolymers used in the optically transparent adhesive composition.

Representative examples of the solvent include ethyl acetate, methyl ethyl ketone, toluene, acetonitrile and the like.

The solvent may be included in an amount of 40 to 85 parts by weight based on 100 parts by weight of the solids contained in the optically transparent adhesive composition.

In the optically transparent adhesive composition of the present invention, the polydimethylsiloxane-based (meth) acrylate compound may be present in a blended state with the photocurable (meth) acrylate copolymer.

The viscosity of the optically transparent adhesive composition of the present invention may be preferably used in the range of 500 cP to 2,500 Cp at 23 ° C.

The optically transparent adhesive composition of the present invention uses a monomer having a low glass transition temperature and a polydimethylsiloxane-based (meth) acrylate compound to secure folding properties, and is based on a curing system based on radical polymerization, a crosslinking agent, and a thermosetting functional group (hydroxy group). By employing a curing system as appropriate, it has a feature of ensuring moisture heat resistance, heat resistance and durability.

The method of preparing the optically transparent adhesive composition of the present invention may be carried out by a method commonly used in this field except as described above. At this time, molecular weight regulators, catalysts and the like used in this field may also be used without limitation.

The method of applying the optically transparent adhesive composition of the present invention is not particularly limited, and examples thereof include bar coating, spin coating, comma coating, gravure coating, and the like. This can be done in a general purpose way. In the coating process, it is preferable to control so that the crosslinking reaction of the functional group of the polyfunctional crosslinking agent contained in an adhesive composition may not progress, from a viewpoint of performing a uniform coating process. Through this, the crosslinking agent forms a crosslinked structure in the curing and aging process after the coating operation, thereby improving the cohesion, adhesive properties, and cuttability of the pressure-sensitive adhesive.

In addition, the application process is preferably performed after sufficiently removing the bubble-inducing components such as volatile components or reaction residues inside the pressure-sensitive adhesive composition. As a result, the crosslinking density or molecular weight of the pressure-sensitive adhesive is too low, the elastic modulus is lowered, and bubbles present between the glass plate and the pressure-sensitive adhesive layer in a high temperature state may be increased to prevent a phenomenon in which scattering bodies are formed inside.

After forming the coating layer of the optically transparent adhesive composition, it is cured through light irradiation. In the present application, for example, when applying an ultraviolet irradiation method, the ultraviolet irradiation may be performed using a means such as a high pressure mercury lamp, an electrodeless lamp or a xenon lamp.

Further, before or after the light irradiation process, an appropriate aging process may be conducted to induce reaction of the functional group of the crosslinking agent in the composition with the thermosetting functional group of the polymer, and the conditions in the process are not particularly limited as long as an appropriate crosslinking reaction can occur. .

The pressure-sensitive adhesive composition for an optical film of the present invention, for example, laminated optical films such as a polarizing film, a retardation film, an anti-glare film, a wide viewing angle compensation film or a brightness enhancement film, or displays the optical film or a laminate thereof. It can be used for the purpose of attaching to adherends such as panels.

In particular, the pressure-sensitive adhesive composition for an optical film of the present invention can be preferably used in a flexible display device.

In addition, the present invention

It provides an optical transparent pressure-sensitive adhesive film, which is prepared by coating the optical transparent pressure-sensitive adhesive composition on a transfer film.

As the transfer film used in the optically transparent adhesive film, a film known in the art may be used without limitation. In addition, the method of manufacturing the optically transparent adhesive film can be used without limitation methods known in the art.

In addition, the present invention

It provides a flat panel display device comprising an adhesive layer formed of the optically transparent adhesive composition of the present invention.

The flat panel display is more preferably a flexible display device.

Hereinafter, the present invention will be described in more detail using examples and comparative examples. However, the following examples are provided to illustrate the present invention, and the present invention is not limited to the following examples and may be variously modified and changed.

Production Example  1-1: Preparation of Acrylic Polymer (A1)

Nitrogen gas was refluxed, and 60 parts by weight of n-butyl acrylate (n-BA) and 40 parts by weight of 4-hydroxybutyl acrylate (4-HBA) were added to a 1 L reactor equipped with a cooling device for easy temperature control. . 120 parts by weight of ethyl acetate (EAc) was added as a solvent, and then nitrogen gas was purged for 60 minutes to remove oxygen. Thereafter, the temperature was maintained at 70 ° C, 0.1 parts by weight of AIBN (azobisisobutyronitrile) as a reaction initiator was added thereto, and reacted for 12 hours to prepare an acrylic polymer (A1) having a weight average molecular weight of 450,000.

Preparation Example 1-2: Preparation of Acrylic Polymer (A2)

Except for using 89 parts by weight of n-butyl acrylate (n-BA) and 11 parts by weight of 4-hydroxybutyl acrylate (4-HBA) in Preparation Example 1 carried out the polymerization reaction in the same manner as the weight average An acrylic polymer (A2) having a molecular weight of 470,000 was prepared.

Preparation Example 1-3: Preparation of Acrylic Polymer (A3)

60 parts by weight of n-butyl acrylate (n-BA) and 40 parts by weight of 4-hydroxybutyl acrylate (4-HBA) in Preparation Example 1 80 parts by weight of n-butyl acrylate (n-BA) and 2- Except that 20 parts by weight of hydroxyethyl acrylate (2-HEA) was used, the polymerization was carried out in the same manner to prepare an acrylic polymer (A3) having a weight average molecular weight of 450,000.

Preparation Example 1-4: Preparation of Acrylic Polymer (A4)

In Preparation Example 1 90 parts by weight of n-butyl acrylate (n-BA) and 90 parts by weight of n-butyl acrylate (n-BA) instead of 20 parts by weight of 4-hydroxybutyl acrylate (4-HBA) and 4- Except that 10 parts by weight of hydroxybutyl acrylate (4-HBA) was used, the polymerization was carried out in the same manner to prepare an acrylic polymer (A4) having a weight average molecular weight of 390,000.

Preparation Example 2-1 Preparation of Photocurable (meth) acrylate Copolymer (B1)

100 parts by weight of the acrylic polymer (A1) solids and 1 part by weight of 2-isocyanatoethyl methacrylate in a 1 L reactor in which nitrogen gas was refluxed and a cooling device was installed to facilitate temperature control. And 0.1 part by weight of dibutyl tindilaulate (DBTDL). Subsequently, the mixture was reacted for 4 hours or more at a temperature of 40 ° C. and atmospheric pressure to prepare a photocurable (meth) acrylate copolymer (B1).

Preparation Example 2-2 Preparation of Photocurable (meth) acrylate Copolymer (B2)

A photocurable (meth) acrylate copolymer (B2) was prepared in the same manner as in Production Example 2-1, except that the acrylic polymer (A2) was used.

Preparation Example 2-3 Preparation of Photocurable (meth) acrylate Copolymer (B3)

A photocurable (meth) acrylate copolymer (B3) was prepared in the same manner as in Production Example 2-1, except that the acrylic polymer (A3) was used.

Preparation Example 2-4 Preparation of Photocurable (Meta) acrylate Copolymer (B4)

A photocurable (meth) acrylate copolymer (B4) was prepared in the same manner as in Production Example 2-1, except that the acrylic polymer (A4) was used.

Preparation Example 3 Preparation of Hard Coating Film for Flexibility Evaluation

<Epoxy siloxane resin manufacturing>

3-Glycidoxypropyltrimethoxysilane (GPTS, Gelest, Inc.) and water were mixed in a ratio of 23.63 g: 2.70 g (0.1 mol: 0.15 mol) and placed in a 100 mL 2 neck flask. Then 0.05 mL of ammonia was added to the mixture as a catalyst and stirred at 60 ° C. for 6 hours to prepare a silonic acid sol.

<Hard Coating Composition Preparation>

The silonic acid sol and diglycidyl ether are mixed in a weight ratio of 100: 10, and 2 parts by weight of triarylsulfonium hexafluoroantimonate salt is mixed with 100 parts by weight of the mixture to prepare a hard coating composition. Prepared.

<Hard Coating Film Manufacturing>

The hard coating composition was coated with a thickness of 50 μm on a 40 μm thick COP (cycloolefin polymer, ZF-16, Zeon) film treated by corona to prepare a film. The film was exposed to a mercury UV (Ultra Violet) lamp (20 mW / cm ² ) for 5 minutes to initiate the reaction with the triarylsulfonium hexafluoroantimonate salt and at 50 ° C. and 50% relative humidity. Moisture heat treatment was performed for 60 minutes under the conditions to form a hard coat film.

Example 1: Preparation of Optical Transparent Adhesive Composition

To 100 parts by weight of the photocurable acrylate copolymer (B1) prepared in Preparation Example 2-1, 20 parts by weight of the monomer represented by the formula (1), 0.07 parts by weight of polyfunctional crosslinking agent (Coronate L, Japan NPU), Pressure-sensitive adhesive composition by mixing 0.2 part by weight of a photopolymerization initiator (hydroxycyclohexylphenyl ketone, irgacure 184, Swiss Chivas Medical Co., Ltd.) and 0.2 part by weight of 3-glycidoxypropyltrimethoxyl silane (Shin-Etsu Co., Ltd. KBM-403) Was prepared.

[Formula 1]

In the above formula

R ₁ is hydrogen,

P is 50.

Example 2: Preparation of Optical Transparent Adhesive Composition

The pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that the monomer represented by the following Formula 2 was used instead of the monomer represented by the formula 1 in Example 1.

[Formula 2]

In the above formula

R ₁ is a methyl group,

R ₂ is an ethylene group,

Q is 50.

Example 3: Preparation of Optical Transparent Adhesive Composition

To 100 parts by weight of the photocurable (meth) acrylate copolymer (B2) prepared in Preparation Example 2-2, 30 parts by weight of the monomer represented by the following formula (3), polyfunctional isocyanate crosslinking agent (Coronate L, manufactured by Japan NPU) A pressure-sensitive adhesive composition was prepared by mixing 0.5 parts by weight and 0.2 parts by weight of a photopolymerization initiator (hydroxycyclohexylphenyl ketone, irgacure 184, Swiss Chivas Specialty Chemical Co., Ltd.).

[Formula 3]

In Chemical Formula 3,

R ₁ is hydrogen,

R ₃ is a hexamethylene group,

R ₄ is an ethylene group,

R is 50.

Comparative Example 1: Preparation of Optical Transparent Adhesive Composition

0.07 parts by weight of a polyfunctional crosslinking agent (Coronate L, manufactured by Japan NPU), 100 parts by weight of the photocurable acrylate copolymer (B3) prepared in Preparation Example 2-3, a photopolymerization initiator (hydroxycyclohexylphenyl ketone, irgacure 184 , 0.2 parts by weight of Swiss Chivas Specialty Chemical (manufactured) and 0.2 parts by weight of 3-glycidoxypropyltrimethoxyl silane (Shin-Etsu Co., Ltd. KBM-403) were prepared to prepare an adhesive composition.

Comparative Example 2: Preparation of Optical Transparent Adhesive Composition

0.07 parts by weight of a polyfunctional crosslinking agent (Coronate L, manufactured by NPU, Japan), a photopolymerization initiator (hydroxycyclohexylphenyl ketone, irgacure 184 based on 100 parts by weight of the photocurable acrylate copolymer (B4) prepared in Preparation Example 2-4. , 0.2 parts by weight of Swiss Chivas Specialty Chemical (manufactured) and 0.2 parts by weight of 3-glycidoxypropyltrimethoxyl silane (Shin-Etsu Co., Ltd. KBM-403) were prepared to prepare an adhesive composition.

Example 4: Preparation of an optically transparent adhesive film

Each of the optically transparent adhesive compositions prepared in Examples 1, 2, 3, Comparative Example 1 and Comparative Example 2 so that the thickness after curing on a 50 μm-thick PET film coated with a silicone release agent is 100 μm. Apply | coated and dried at 100 degreeC for 5 minutes, Example 4-1 (using the optically transparent adhesive composition of Example 1), Example 4-2 (using the optically transparent adhesive composition of Example 2), Example 4-3 (The optical transparent adhesive composition of Example 3 used), the optical transparent adhesive film of Comparative Example 4-1 (using the optical transparent adhesive composition of Comparative Example 1), and Comparative Example 4-2 (using the optical transparent adhesive composition of Comparative Example 2) Was prepared.

Example 5: Preparation of Laminate with Pressure-sensitive Adhesive Layer

PET film having a thickness of 100 μm using the optically transparent adhesive film prepared in Examples 4-1, 4-4, 4-4, Comparative Example 4-1, and Comparative Example 4-2 (100um manufactured by Mitsubishi Corporation) PET) laminated on the pressure-sensitive adhesive layer, and irradiated with the amount of light of 1000mJ / cm ² using a UV lamp (fusion yarn) in the release film direction Example 5-1, Example 5-2, Example 5-3, The laminated body in which the adhesive layer of Comparative Example 5-1 and Comparative Example 5-2 was formed was manufactured.

Example 6: Preparation of Hard Coating Film / Adhesive Layer / PET Laminate for Flexibility Evaluation

The laminated body of Example 5-1, Example 5-2, Example 5-3, Comparative Example 5-1, and Comparative Example 5-2 was cut | judged to the magnitude | size of 50 mm x 100 mm. Subsequently, the release PET film attached to the pressure-sensitive adhesive layer of the cut laminate was peeled off, adhered onto a hard coating film for evaluation of flexibility prepared in Preparation Example 3 having a size of 50 mm × 100 mm, and an autoclave (50 ° C.). , 5 atmospheres) for about 20 minutes, and cured for 24 hours in a constant temperature and humidity conditions (23 ℃, 50% relative humidity), respectively Example 6-1, Example 6-2, Example 6-3, The hard coat film / adhesive layer / PET (100 micrometers) laminated body for the flexibility evaluation of the comparative example 6-1 and the comparative example 6-2 was manufactured.

Test Example: Evaluation of Physical Properties of Optical Transparent Adhesive Composition

1. Folding characteristic evaluation

<Evaluation method>

Evaluation standard: IEC 62715

Evaluation equipment: planar no-load U-fold tester (DLDMLH-FS)

Equipment maker: YUASA SYSTEM (Japan)

Evaluation condition: -20 ° C / 10,000 times (flexing the hard coating side to be folded inward)

Example 6-1, Example 6-2, Example 6-3, Comparative Example 6-1 and Comparative Example 6-2 prepared in Example 6 for the hard coating film / adhesive layer / PET laminate To evaluate the folding properties according to the above evaluation method is shown in Table 1 below.

<Evaluation Criteria>

(Circle): No defect modes, such as bubble, peeling, and a crack, are observed in a laminated body.

(Triangle | delta): Fine defect mode is visually visually recognized by a laminated body.

X: The defective mode which was visually recognized by the folding part of a laminated body is visually recognized.

2. Durability Rating

(1) heat resistance evaluation

Example 6-1, Example 6-2, Example 6-3, Comparative Example 6-1 and Comparative Example 6-2 prepared in Example 6 for the hard coating film / adhesive layer / PET laminate After leaving for 1,000 hours at a temperature of 80 ℃ to observe the occurrence of bubbles or peeling to evaluate the heat resistance and the results are shown in Table 1 below.

<Evaluation Criteria>

◎: no bubbles or peeling

○: bubble or peeling <5 pieces

△: 5 ≤ air bubbles or exfoliation <10

×: 10 ≤ air bubbles or peeling

(2) Moisture resistance test

Example 6-1, Example 6-2, Example 6-3, Comparative Example 6-1 and Comparative Example 6-2 prepared in Example 6 for the hard coating film / adhesive layer / PET laminate After being left for 1,000 hours at a temperature of 60 ° C. and 90% RH, it was observed whether bubbles or peeling occurred. At this time, immediately after evaluating the state of the specimen left at room temperature for 24 hours and observed to evaluate the heat and humidity resistance and the results are shown in Table 1 below.

<Evaluation Criteria>

◎: no bubbles or peeling

○: bubble or peeling <5 pieces

△: 5 ≤ air bubbles or exfoliation <10

×: 10 ≤ air bubbles or peeling

3. Evaluation of adhesion

The specimens were prepared by cutting the pressure-sensitive adhesive forming laminates prepared in Examples 5-1, 5-2, 5-5, Comparative Example 5-1, and Comparative Example 5-2 to a size of 25 mm × 100 mm. It was. Subsequently, the release PET film adhered to the adhesive layer was peeled off, and the lamination agent in which the adhesive layer was formed was attached to the alkali free glass using the roller of 2 kg according to the provision of JIS Z 0237. Samples were prepared by compressing the alkali free glass with the laminating agent in an autoclave (50 ° C., 5 atmospheres) for about 20 minutes and storing for 24 hours at constant temperature and humidity conditions (23 ° C., 50% relative humidity). After that, using the TA equipment (Texture Analyzer, manufactured by Stable Micro Systems Co., Ltd.), the adhesion was measured while peeling the laminate from an alkali free glass at a peel rate of 300 mm / min and a peel angle of 180 degrees. 1 is shown.

TABLE 1

TABLE 2

As confirmed from the test results of Table 1 and Table 2, the optically transparent pressure-sensitive adhesive composition of the embodiment of the present invention was confirmed that all excellent folding properties, heat-and-moisture resistance, heat resistance and adhesion. In particular, the folding properties were found to be remarkably superior compared to the optically transparent adhesive compositions of the comparative example. In the case of adhesion, it was confirmed that the polydimethylsiloxane-based (meth) acrylate compound was less than the comparative example.

Claims (12)

1. Photocurable (meth) acrylate copolymers; Polydimethylsiloxane-based (meth) acrylate compounds; And a photopolymerization initiator, comprising:

   The photocurable (meth) acrylate copolymer includes 95 to 99.9 wt% of a hydroxy group-containing acrylic copolymer and 0.1 to 5 wt% of an isocyanate group-containing (meth) acrylate monomer based on the total weight of structural units included in the copolymer. The hydroxyl group-containing acrylic copolymer and the isocyanate group-containing (meth) acrylate monomer form a urethane bond,

   The hydroxy group-containing acrylic copolymer is 50 to 98% by weight of C ₁ ~ C ₁₂ linear or branched alkyl (meth) acrylate monomers and 2 to 50% by weight of hydroxy group-containing polymerizable monomers based on the total weight of monomers in the copolymer. To include, the weight average molecular weight is 200,000 to 1 million optically transparent pressure-sensitive adhesive composition.
2. The method according to claim 1,

   The hydroxy group-containing polymerizable monomer is an optically transparent adhesive composition, characterized in that the monomer having one hydroxyl group and one ethylenically unsaturated bond in the molecule.
3. The method according to claim 2,

   Wherein the C ₁ ~ C straight or branched chain alkyl (meth) acrylate monomer of ₁₂ is straight or branched of the C ₁ ~ C ₁₂ The glass transition temperature of -70 ~ -50 ℃-chain alkyl (meth) acrylate monomer,

   The monomer having one hydroxyl group and one ethylenically unsaturated bond in the molecule is an optically transparent adhesive composition, characterized in that the hydroxyl group-containing acrylate monomer having a glass transition temperature of -60 ~ -40 ℃.
4. The method according to claim 1,

   The polydimethylsiloxane-based (meth) acrylate compound is an optically transparent adhesive composition, characterized in that at least one selected from the compounds represented by the following formula (1) to:

   [Formula 1]

   

   [Formula 2]

   

   [Formula 3]

   

   In Chemical Formulas 1 to 3,

   Each R ₁ is independently hydrogen or methyl;

   R ₂ is a C ₁ to C ₅ straight or branched alkylene group,

   Each R ₃ is independently a group derived from a diisocyanate compound with an —N (H) —C (O) — group bonded to both sides thereof,

   R ₄ is a C ₁ to C ₅ straight or branched alkylene group,

   P, Q, and R are each independently a natural number of 3 to 100.
5. The method according to claim 1,

   The optically transparent adhesive composition is based on 100 parts by weight of the photocurable (meth) acrylate copolymer 10 to 50 parts by weight of a polydimethylsiloxane (meth) acrylate compound and 0.1 to 5 photoinitiator An optically transparent adhesive composition comprising a weight part.
6. The method according to claim 5,

   The optically transparent adhesive composition further comprises 0.02 to 5 parts by weight of a multifunctional crosslinking agent based on 100 parts by weight of the photocurable (meth) acrylate copolymer.
7. The method according to claim 6,

   The polyfunctional crosslinking agent is a thermosetting polyfunctional isocyanate crosslinking agent or a polyfunctional (meth) acrylate crosslinking agent.
8. The method according to claim 5 or 6,

   The optically transparent adhesive composition further comprises 40 to 85 parts by weight of the solvent based on 100 parts by weight of the solids contained in the optically transparent adhesive composition.
9. The method according to claim 1,

   The isocyanate group-containing (meth) acrylate-based monomer is isocyanate C ₁ ~ C ₁₀ linear or branched chain alkyl (meth) acrylate, characterized in that the optically transparent adhesive composition.
10. An optically transparent adhesive film prepared by coating the optical transparent adhesive composition of claim 1 on a transfer film.
11. A flat panel display comprising an adhesive layer formed of the optically transparent adhesive composition of claim 1.
12. The method according to claim 10,

    The flat panel display device of claim 1, wherein the flat panel display device is a flexible display device.