KR20180031330A - Optically Clear Adhesive Composition, and Optically Clear Adhesive Film comprising the Same, and Flat Panel Display - Google Patents

Abstract

Provided is an optical transparent adhesive composition containing (A) a photocurable (meth)acrylate copolymer; (B) an acrylate copolymer; and (C) a photopolymerization initiator. Moreover, provided are an optical transparent adhesive film comprising the same, and a flat display device. According to the present invention, it is possible to secure excellent durability.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical transparent pressure sensitive adhesive composition, an optical transparent pressure sensitive adhesive film containing the same, and a flat panel display device,

The present invention relates to an optical transparent pressure-sensitive adhesive composition, an optical transparent pressure-sensitive adhesive film containing the same, and a flat panel display.

A flat panel display device includes a liquid crystal display (LCD), a plasma display panel (PDP), and an organic electroluminescence display (OLED).

Such a flat panel display device includes a display panel and an optical film. As the optical film, a polarizing film, a retardation film, an anti-glare film, a wide viewing angle compensation film, a brightness enhancement film, and the like are used. When these optical films are laminated to each other or the optical film is adhered to the display panel, an optical transparent pressure-sensitive adhesive (OCA) is used. Therefore, optical transparent pressure sensitive adhesive (OCA) should have good heat resistance, heat resistance and adhesion with basic optical characteristics.

Particularly, in recent years, flexible display devices are being developed in a competitive manner. Flexible display devices are subject to bending stresses because the device itself is bending, rolling, and folding, so that the display panels and optical films included in the device are also subjected to bending stress. Therefore, the optical transparent pressure sensitive adhesive (OCA) used in flexible displays is required to be further strengthened and diversified in properties.

For example, the optical transparent tackifier (OCA) used in flexible display devices should have excellent folding properties to allow flexible folding of the device. Particularly, considering the case where the flexible display device is used for a long period of time at a low temperature, the folding property at low temperature should be excellent.

Further, the optical transparency adhesive (OCA) used in the flexible display device is required to have enhanced moisture resistance and heat resistance. This is because the flexible display device repeats the folding and unfolding process during use, so that the possibility of penetration of moisture through the folded and expanded portions is increased.

Also, display panels and optical films included in the device are subject to bending stresses as well, such as bending, rolling, folding, and the like. Therefore, since the laminated display panel and the optical films are easily separated from each other, better adhesion is required, and more excellent durability is also required.

However, optical transparent adhesives (OCA) known to date do not sufficiently provide the above-mentioned properties required for a flexible display device.

Korean Patent Publication No. 10-2016-0085759

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned problems of the prior art, and it is an object of the present invention to provide an optical transparent pressure-sensitive adhesive (OCA) composition capable of sufficiently satisfying the folding property, moisture resistance, heat resistance and adhesion required in a flexible display device The purpose.

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

According to the present invention,

A) a photocurable (meth) acrylate copolymer; B) acrylate copolymers; And C) a photopolymerization initiator,

(A) the photocurable (meth) acrylate copolymer contains 95 to 99.9% by weight of a hydroxy group-containing acrylic copolymer and 0.1 to 5% by weight of an isocyanate group-containing (meth) acrylate monomer based on the total weight of the constituent units contained in the copolymer, Wherein the hydroxy group-containing acrylic copolymer and the isocyanate group-containing (meth) acrylate monomer form a urethane bond,

The hydroxy group-containing acrylic copolymer is obtained by copolymerizing 80 to 98% by weight of a linear or branched C ₄ to C ₁₂ alkyl acrylate monomer having a glass transition temperature of -70 to -50 ° C. based on the total weight of the monomers contained in the copolymer, (Meth) acrylate copolymer comprising 2 to 20% by weight of a C ₂ to C ₆ linear or branched alkyl acrylate monomer and having a weight average molecular weight of 500,000 to 2,000,000,

The acrylate copolymer of B) is prepared by copolymerizing 80 to 95% by weight of a straight chain or branched alkyl acrylate monomer having ₄ to ₁₂ carbon atoms and an adhesion promoter-containing polymerizable monomer 5 (based on the total weight of the monomers contained in the copolymer) To 20% by weight, and does not contain a photopolymerizable group and has a weight average molecular weight of 10,000 to 100,000,

Wherein the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B) are contained in a weight ratio of 95: 5 to 70:30.

Further, according to the present invention,

The present invention provides an optical transparent pressure-sensitive adhesive film which is prepared by coating the above-mentioned optical transparent pressure-sensitive adhesive composition of the present invention onto a transfer film.

Further, according to the present invention,

And a pressure-sensitive adhesive layer formed from the optical transparent pressure-sensitive adhesive composition of the present invention.

The optical transparent pressure sensitive adhesive (OCA) composition and the optical transparent pressure sensitive adhesive film of the present invention provide not only a flat panel display but also a folding property, a wet heat resistance, a heat resistance and an adhesion property sufficient for use in a flexible display device, to provide.

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

(A) a photocurable (meth) acrylate copolymer; B) acrylate copolymers; And C) a photopolymerization initiator,

(A) the photocurable (meth) acrylate copolymer contains 95 to 99.9% by weight of a hydroxy group-containing acrylic copolymer and 0.1 to 5% by weight of an isocyanate group-containing (meth) acrylate monomer based on the total weight of the constituent units contained in the copolymer, Wherein the hydroxy group-containing acrylic copolymer and the isocyanate group-containing (meth) acrylate monomer form a urethane bond,

The hydroxy group-containing acrylic copolymer is obtained by copolymerizing 80 to 98% by weight of a linear or branched C ₄ to C ₁₂ alkyl acrylate monomer having a glass transition temperature of -70 to -50 ° C. based on the total weight of the monomers contained in the copolymer, (Meth) acrylate copolymer comprising 2 to 20% by weight of a C ₂ to C ₆ linear or branched alkyl acrylate monomer and having a weight average molecular weight of 500,000 to 2,000,000,

The acrylate copolymer of B) is prepared by copolymerizing 80 to 95% by weight of C4 to C12 linear or branched alkyl acrylate monomers with 5 to 20% by weight of an adhesion promoter, based on the total weight of the monomers contained in the copolymer % By weight, an acrylate copolymer containing no photo-crosslinkable functional group and having a weight average molecular weight of 10,000 to 100,000,

Wherein the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B) are contained in a weight ratio of 95: 5 to 70:30.

In the optical transparent pressure-sensitive adhesive composition of the present invention, the photo-curable (meth) acrylate copolymer of A) includes C ₄ to C ₁₂ linear or branched alkyl acrylate monomers having a glass transition temperature of -70 to -50 ° C, High molecular weight and high crosslinking density through radical crosslinking between the acrylic functional groups connected by urethane bond, which is excellent in heat resistance and durability, and the hydroxy C ₂ -C ₆ linear or branched alkyl acrylate monomer It is excellent in resistance to moisture and heat, and adhesion.

Further, in the optical transparent pressure-sensitive adhesive composition of the present invention, the acrylate copolymer of B) is low in molecular weight and does not contain a photo-crosslinkable functional group and does not form a crosslinking even after the photo-crosslinking reaction, When the copolymer is contained in a large amount, the low molecular weight acrylate copolymer after the formation of the pressure-sensitive adhesive layer migrates at the interface and bleeds-out, thereby improving the durability and deteriorating the adhesive strength. Containing polymerizable monomer is contained in a large amount, excellent heat and humidity resistance and adhesion can be obtained.

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

The photocurable (meth) acrylate copolymer of A) comprises 80 to 98 parts by weight of a linear or branched C ₄ to C ₁₂ alkyl (meth) acrylate monomer having a glass transition temperature of -70 to -50 ° C, hydroxy C ₂ ~ C ₆ linear or preparing a branched chain alkyl acrylate monomer, 2 to 20 parts by weight of a branched or end-acrylate copolymer main chain of the thermosetting functional group (hydroxyl group) introduced by copolymerizing and then containing an isocyanate group ( (Meth) acrylate monomer with an isocyanate group-containing (meth) acrylate monomer by reacting at least part of the thermosetting functional group (hydroxyl group) of the main chain with an isocyanate group-containing monomer by reacting the main chain with the main chain.

The main chain can be produced by a conventional polymerization method such as solution polymerization, photo polymerization, bulk polymerization, suspension polymerization or emulsion polymerization. .

Examples of C ₄ to C ₁₂ linear or branched alkyl (meth) acrylate monomers having a glass transition temperature of -70 to -50 ° C, contained in a polymerized form in the photocurable (meth) acrylate copolymer of A) n-propyl acrylate, n-butyl acrylate, t-butyl acrylate, sec-butyl acrylate, pentyl acrylate, 2- ethylbutyl acrylate, And the like. These may be used alone or in combination of two or more, and one or more monomers selected from n-butyl acrylate and 2-ethylhexyl acrylate may be preferably used.

When the glass transition temperature (Tg) of the C ₄ to C ₁₂ linear or branched alkyl acrylate monomer is less than -70 ° C, it is difficult to use because of economical efficiency. When the glass transition temperature is higher than -50 ° C, A problem of degradation occurs.

Examples of the hydroxy C ₂ -C ₆ linear or branched alkyl acrylate monomer contained in the form of the polymerizable (meth) acrylate copolymer of A) include 2-hydroxyethyl acrylate, 3-hydroxy Propyl acrylate, 4-hydroxybutyl acrylate, 5-hydroxypentyl acrylate, and 6-hydroxyhexyl acrylate. These may be used singly or in combination of two or more. The hydroxy C ₂ -C ₆ linear or branched alkyl acrylate monomer contained in polymerized form in the photocurable (meth) acrylate copolymer of A) is preferably 2-hydroxybutyl acrylate and 4-hydroxy Hydroxybutyl acrylate, hydroxybutyl acrylate, and hydroxybutyl acrylate.

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

(A)

In the above formula

R ₁ is a C ₄ to C ₁₂ linear or branched alkyl group,

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

R < ₃ > is hydrogen or methyl,

O is a natural number from 2 to 6,

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

In the hydroxy group-containing acrylic copolymer, the C ₄ -C ₁₂ straight chain or branched alkyl acrylate monomer having a glass transition temperature (Tg) of -70 to -50 ° C. is contained in an amount of 80 to 98% by weight, and a hydroxy C It is preferable that the ₂ to ₆ linear or branched alkyl acrylate monomers are contained in an amount of 2 to 20% by weight. When the amount of the hydroxy C ₂ -C ₆ linear or branched alkyl acrylate monomer is less than 2 parts by weight, the hydroxy group, which is a hydrophilic group, is insufficient in the pressure-sensitive adhesive, so moisture can not be caught in the pressure-sensitive adhesive layer, In the case where the pressure-sensitive adhesive contains more than 20 parts by weight, the pressure-sensitive adhesive absorbs excess moisture to expand the volume and lower the cohesive force, resulting in interfacial peeling and air bubbles. do.

The photocurable (meth) acrylate copolymer of A) above may further comprise polymerized forms of other copolymerizable monomers known in the art. The kind of the other copolymerizable monomer is not particularly limited and includes, for example, (meth) acrylonitrile, (meth) acrylamide, N-methyl (meth) acrylamide or N-butoxymethyl The same nitrogen containing monomers; Styrene-based monomers such as styrene or methylstyrene; Glycidyl (meth) acrylate; Or vinyl esters of carboxy acid such as vinyl acetate, but are not limited thereto.

When the other copolymerizable monomers are included, the content thereof is preferably adjusted to 20 parts by weight or less based on 100 parts by weight of the total amount of monomers described above in consideration of flexibility and peel strength.

In the photocurable (meth) acrylate copolymer of A), the weight average molecular weight means a value converted to standard polystyrene measured by GPC (Gel Permeation Chromatograph).

As the isocyanate group-containing (meth) acrylate monomer, isocyanato C ₁ -C ₁₀ linear or branched alkyl (meth) acrylate may be used. Examples of the C ₁ -C ₁₀ linear or branched alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, Nonyl, decanyl, etc. Of these, ethyl, propyl Etc. may be preferably used.

For example, the isocyanate group-containing (meth) acrylate-based monomer may be a compound represented by the following formula (B).

≪ Formula B >

In the formula (A), R is -H or -CH ₃ , and n is an integer of 1 to 10.

The isocyanate group-containing (meth) acrylate monomer may be a compound in which R is -CH ₃ and n is an integer of 2, that is, 2-isocyanatoethyl methacrylate. have.

The isocyanate group-containing (meth) acrylate monomer may be contained in an amount of 0.1 to 5.0% by weight based on the total weight of the constituent units contained in the photocurable (meth) acrylate copolymer. When the isocyanate group-containing (meth) acrylate monomer is contained in an amount of less than 0.1% by weight, the cohesive force and heat resistance of the pressure-sensitive adhesive composition may deteriorate. When the amount exceeds 5.0% by weight, Can be lowered.

The adhesion promoter-containing polymerizable monomer is a polymerizable monomer containing a polar group or a reactive functional group.

The adhesion promoter-containing polymerizable monomer is a compound of formula (1); A compound of formula 2; A compound of formula 3; A chemical of formula 4; A compound of formula 5; A compound of formula 6; A compound of formula 7; And a compound of formula (8).

≪ Formula 1 >

(2)

(3)

≪ Formula 4 >

≪ Formula 5 >

(6)

≪ Formula 7 >

(8)

X is a conjugate base of a strong acid with pKa < -3, X is, for example, PF5, SbF6, mesylate (OMs), tosylate (OTs), triflate Bis (fluorosulfonyl) imide (FSI), bis (trifluoromethylsulfonyl) imide (TFSI), and the like.

Butyl acrylate, t-butyl (meth) acrylate, sec. (Meth) acrylate, and the like. Examples of the C ₄ to C ₁₂ linear or branched alkyl (meth) (Meth) acrylate, isooctyl (meth) acrylate, isooctyl (meth) acrylate, isohexyl (meth) acrylate, Nonyl (meth) acrylate, etc. These may be used singly or in combination of two or more kinds. One or more monomers selected from n-butyl acrylate and 2-ethylhexyl acrylate are preferably used .

B), the C ₄ -C ₁₂ linear or branched alkyl acrylate monomer is contained in an amount of 80 to 95% by weight, the polymerizable monomer containing an adhesion promoter is contained in an amount of 5 to 20% by weight, . When the amount of the polymerizable monomer containing an adhesion promoter is less than 5% by weight, the low molecular weight acrylate copolymer migrates at the interface and bleeds out, thereby reducing the durability and the adhesive strength. If it exceeds 20% by weight, the flexibility of the pressure-sensitive adhesive layer may be insufficient and the folding property may be deteriorated.

When the weight average molecular weight of the acrylate copolymer of B) is less than 10,000, bleeding out is serious and durability may be deteriorated. When the weight average molecular weight is more than 100,000, there is a problem that the effect of improving the adhesion strength may be insufficient have.

In the optical transparent pressure-sensitive adhesive composition, it is preferable that the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B) are contained in a weight ratio of 95: 5 to 70:30. If the acrylate copolymer of (B) is less than 5 parts by weight based on 100 parts by weight of the total content of the photocurable (meth) acrylate copolymer of (A) and the acrylate copolymer of (B) When the acrylate copolymer of B) exceeds 30 parts by weight based on 100 parts by weight of the total content of the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B), the folding property is lowered Problems can arise.

The optical transparent pressure-sensitive adhesive composition of the present invention comprises C) a photopolymerization initiator in order to efficiently induce a reaction of a radical polymerizable group. The C) photopolymerization initiator can be used in polymerization of the hydroxy group-containing acrylic copolymer, and ultimately, the optical transparent pressure-sensitive adhesive composition is included together with the photocurable (meth) acrylate copolymer.

The C) photopolymerization initiator is not particularly limited, and a photopolymerization initiator known in the art may be used. Specifically, typical initiators that can initiate photopolymerization by generating radicals by irradiation with ultraviolet rays or the like, such as benzoin-based initiators, hydroxyketone-based initiators, amino ketone-based initiators, or phosphine oxide-based initiators.

If the content of the C) photopolymerization initiator is too small, the effect due to the addition may be insignificant. If the content is too large, the physical properties such as durability and transparency may be adversely affected. .

The C) photopolymerization initiator is preferably used 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 total content of the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B) .

The optical transparent pressure sensitive adhesive composition of the present invention may further comprise a multifunctional crosslinking agent. Such a polyfunctional crosslinking agent is not particularly limited, and those known in the art can be used. Specific examples thereof include a thermosetting polyfunctional isocyanate crosslinking agent and a polyfunctional (meth) acrylate crosslinking agent.

The multifunctional crosslinking agent may further comprise 0.02 to 5 parts by weight based on 100 parts by weight of the total content of the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B).

The optical transparent pressure sensitive adhesive composition of the present invention may further comprise a silane coupling agent. The kind of the coupling agent is not particularly limited, and coupling agents conventionally known in the art of pressure-sensitive adhesive production can be used. Examples of the silane coupling agent include gamma-glycidoxypropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, gamma-glycidoxypropyltriethoxy Silane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-methacryloxypropyltriethoxysilane, gamma -aminopropyl Trimethoxysilane, gamma-aminopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, and the like.

The initiator of the silane coupling agent is used in an amount of 0.01 to 5 parts by weight, preferably 0.01 part by weight, based on 100 parts by weight, of the total content of the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B) To 1 part by weight.

The optical transparent pressure sensitive adhesive composition of the present invention may further comprise a tackifier for adjusting the tack performance.

In addition, it may further include at least one additive selected from the group consisting of an epoxy resin, a curing agent, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, a defoamer, a surfactant and a plasticizer.

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

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

The solvent may include 40 to 85 parts by weight based on 100 parts by weight of the total content of the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B).

The viscosity of the optical transparent pressure-sensitive adhesive composition of the present invention preferably ranges from 500 cP to 2,500 Cp at 23 캜.

The method for producing the optical transparent pressure-sensitive adhesive composition of the present invention can 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 can be used without limitation.

The method of applying the optical transparency pressure-sensitive adhesive composition of the present invention is not particularly limited, and examples thereof include a bar coating method, a spin coating method, a comma coating method, and a gravure coating method. Can be performed in a general-purpose manner. From the viewpoint of performing a uniform coating process, it is preferable to control the crosslinking reaction of functional groups of the polyfunctional crosslinking agent contained in the pressure-sensitive adhesive composition in the coating process. Through this, the crosslinking agent forms a crosslinked structure during the curing and aging process after the coating operation, so that the cohesive force, the adhesive property and the cuttability of the pressure-sensitive adhesive can be improved.

Further, the application process is preferably performed after sufficiently removing the bubble-inducing component such as volatile components or reaction residues in the pressure-sensitive adhesive composition. Accordingly, the crosslinking density or the molecular weight of the pressure-sensitive adhesive is too low to lower the elastic modulus, and bubbles existing between the glass plate and the pressure-sensitive adhesive layer at a high temperature are increased to form a scattering body therein.

After forming a coating layer of the optical transparent pressure-sensitive adhesive composition, it is cured by light irradiation. In the present application, for example, in the case of applying the ultraviolet ray irradiation method, the ultraviolet ray irradiation can be performed by means of a high-pressure mercury lamp, an electrodeless lamp, or a xenon lamp.

In addition, a suitable aging step may be carried out before or after the light irradiation step to induce the 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 a proper crosslinking reaction can take place .

The pressure-sensitive adhesive composition for an optical film of the present invention can be obtained by, for example, laminating 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, And may be used for adhering to an adherend such as a panel or the like.

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

In addition,

Wherein the optical transparent pressure-sensitive adhesive composition is prepared by coating the above-mentioned optical transparent pressure-sensitive adhesive composition onto a transfer film.

As the transfer film used in the optical transparent pressure-sensitive adhesive film, films known in this field can be used without limitation. In addition, a method for producing an optical transparent pressure-sensitive adhesive film can be used without limitation in a method known in the art.

In addition,

And a pressure-sensitive adhesive layer formed from the optical transparent pressure-sensitive adhesive composition of the present invention.

It is more preferable that the flat panel display device is a flexible display device.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are intended to illustrate the present invention, and the present invention is not limited by the following examples, but may be variously modified and changed.

Manufacturing example  1-1. Acrylate  Preparation of Copolymer (A1)

80 parts by weight of n-butyl acrylate (n-BA) and 20 parts by weight of 4-hydroxybutyl acrylate (4-HBA) were added to a 1 L reactor equipped with a cooling device to easily regulate the temperature, . After 120 parts by weight of ethyl acetate (EAc; ethyl acetate) was added as a solvent, nitrogen gas was purged for oxygen removal for 60 minutes. Thereafter, the temperature was maintained at 70 占 폚, and 0.5 parts by weight of AIBN (azobisisobutyronitrile) as a reaction initiator was added thereto and reacted for 12 hours to prepare an acrylate polymer (A1) having a weight average molecular weight of 1,200,000.

Manufacturing example  1-2. Acrylate  Preparation of Copolymer (A2)

Except that 90 parts by weight of n-butyl acrylate (n-BA) and 10 parts by weight of 4-hydroxybutyl acrylate (4-HBA) were used in Production Example 1, An acrylate polymer (A2) having a molecular weight of 1,280,000 was prepared.

Manufacturing example  1-3. Acrylate  Preparation of Copolymer (A3)

Polymerization was carried out in the same manner as in Production Example 1 except that 98 parts by weight of n-butyl acrylate (n-BA) and 2 parts by weight of 4-hydroxybutyl acrylate (4-HBA) An acrylate polymer (A3) having a molecular weight of 1.19 million was prepared.

Manufacturing example  1-4. Acrylate  Preparation of Copolymer (A4)

Except that 99.5 parts by weight of n-butyl acrylate (n-BA) and 0.5 part by weight of 2-hydroxyethyl acrylate (2-HBA) were used in Production Example 1, An acrylate polymer (A4) having a molecular weight of 1,600,000 was prepared.

Manufacturing example  2-1: Photocurable  ( Meta ) Acrylate  Preparation of Copolymer (B1)

100 parts by weight of the solid content of the acrylate copolymer (A1) and 1 part by weight of 2-isocyanatoethyl methacrylate (1-isocyanatoethyl methacrylate) were added to a 1 L reactor equipped with a cooling device And 0.1 part by weight of dibutyl tin dilaurate (DBTDL). Subsequently, the reaction was carried out at a temperature of 40 ° C and at normal pressure for 4 hours or more to prepare a photocurable (meth) acrylate copolymer (B1).

Manufacturing example  2-2: Photocurable  ( Meta ) Acrylate  Preparation of Copolymer (B2)

(Meth) acrylate copolymer (B2) was prepared in the same manner as in Production Example 2-1 except that the acrylate copolymer (A2) was used.

Manufacturing example  2-3: Photocurable  ( Meta ) Acrylate  Preparation of Copolymer (B3)

(Meth) acrylate copolymer (B3) was prepared in the same manner as in Production Example 2-1 except that the acrylate copolymer (A3) was used.

Manufacturing example  2-4: Photocurable  ( Meta ) Acrylate  Preparation of Copolymer (B4)

100 parts by weight of the solid content of the acrylate copolymer (A4) and 2 parts by weight of 2-isocyanatoethyl methacrylate (0.1 parts by weight) were added to a 1 L reactor equipped with a cooling device to easily regulate the temperature, And 0.1 part by weight of dibutyl tin dilaurate (DBTDL). Subsequently, the reaction was carried out at a temperature of 40 ° C and at normal pressure for 4 hours or more to prepare a photocurable (meth) acrylate copolymer (B4).

Manufacturing example  3-1. Acrylate  Preparation of Copolymer (C1)

90.9 parts by weight of n-butyl acrylate (n-BA) and 9.1 parts by weight of the monomer represented by the formula (2) were added to a 1 L reactor equipped with a cooling device to easily regulate the temperature. After 120 parts by weight of ethyl acetate (EAc; ethyl acetate) was added as a solvent, nitrogen gas was purged for oxygen removal for 60 minutes. Thereafter, the temperature was maintained at 70 占 폚, and 0.5 part by weight of AIBN (azobisisobutyronitrile) as a reaction initiator was added and reacted for 12 hours to prepare an acrylate polymer (C1) having a weight average molecular weight of 55,000.

(2)

Manufacturing example  3-2. Acrylate  Preparation of Copolymer (C2)

An acrylate polymer (C2) having a weight average molecular weight of 69,000 was prepared in the same manner as in Production Example 3-1, except that the monomer of the formula (3) was used instead of the monomer of the formula (2).

(3)

Manufacturing example  3-3. Acrylate  Preparation of Copolymer (C3)

An acrylate polymer (C3) having a weight average molecular weight of 51,000 was prepared in the same manner as in Production Example 3-1, except that the monomer of the formula (4) was used instead of the monomer of the formula (2).

&Lt; Formula 4 >

Manufacturing example  3-4. Acrylate  Preparation of Copolymer (C4)

An acrylate polymer (C4) having a weight average molecular weight of 51,000 was prepared in the same manner as in Production Example 3-1, except that the monomer of the formula (6) was used instead of the monomer of the formula (2).

(6)

Manufacturing example  3-5. Acrylate  Preparation of Copolymer (C5)

An acrylate polymer (C5) having a weight average molecular weight of 78,000 was prepared in the same manner as in Production Example 3-1 except that the monomer of the formula (6) was used instead of the monomer of the formula (2).

&Lt; Formula 7 >

, 여기서 X는 = 트리플레이트(Triflate; OTf)임.

, Where X = triflate (OTf).

Manufacturing example  4: Flexibility  For evaluation Hard coating  Production of film

&Lt; Preparation of epoxy siloxane resin &

3-glycidoxypropyltrimethoxysilane (GPTS, Gelest) and water were mixed at 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 as a catalyst to the mixture, and the mixture was stirred at 60 ° C for 6 hours to prepare a silanol acid sol.

&Lt; Preparation of hard coating composition >

The silylated sol and diglycidyl ether were mixed in a weight ratio of 100: 10, and 2 parts by weight of triarylsulfonium hexafluoroantimonate salt was mixed with 100 parts by weight of the mixture to prepare a hard coating composition. .

&Lt; Preparation of hard coating film &

The hard coating composition was coated on a COP (cycloolefin polymer, ZF-16, Zeon Co.) film having a thickness of 40 탆, which had been surface treated with corona, to a thickness of 50 탆 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 triarylsulfonium hexafluoroantimonate salt to generate an acid, And subjected to water heat treatment for 60 minutes under a relative humidity condition to form a hard coating film.

Example  1: Preparation of optical transparent pressure-sensitive adhesive composition

80 parts by weight of the photocurable (meth) acrylate copolymer (B1) prepared in Preparation Example 2-1 and 20 parts by weight of the (meth) acrylate copolymer (C1) prepared in Preparation Example 3-1, 0.5 parts by weight of a polyfunctional isocyanate crosslinking agent (Coronate L, manufactured by NPU of Japan) based on 100 parts by weight of the total content of the photocurable (meth) acrylate copolymer (B1) and the acrylate copolymer (C1), 0.5 parts by weight of a photopolymerization initiator Hexyl phenyl ketone, irgacure 184, and 0.2 part by weight of Ciba Specialty Chemicals, Switzerland) to prepare a pressure-sensitive adhesive composition.

Example  2: Preparation of optical transparent pressure-sensitive adhesive composition

Except that 70 parts by weight of the photocurable (meth) acrylate copolymer (B2) prepared in Preparation Example 2-1 and 30 parts by weight of the (meth) acrylate copolymer (C2) prepared in Preparation Example 3-2 were used And a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1.

Example  3: Preparation of optical transparent pressure-sensitive adhesive composition

Except that 75 parts by weight of the photocurable (meth) acrylate copolymer (B2) prepared in Preparation Example 2-1 and 25 parts by weight of the (meth) acrylate copolymer (C3) prepared in Preparation Example 3-3 were used And a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1.

Example  4: Preparation of optical transparent pressure-sensitive adhesive composition

Except that 85 parts by weight of the photocurable (meth) acrylate copolymer (B2) prepared in Preparation Example 2-1 and 15 parts by weight of the (meth) acrylate copolymer (C4) prepared in Preparation Example 3-3 were used And a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1.

Example  5: Preparation of optical transparent pressure-sensitive adhesive composition

Except that 95 parts by weight of the photocurable (meth) acrylate copolymer (B2) prepared in Preparation Example 2-1 and 5 parts by weight of the (meth) acrylate copolymer (C5) prepared in Preparation Example 3-3 were used And a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1.

Comparative Example  One: Preparation of optical transparent pressure-sensitive adhesive composition

0.5 part by weight of a polyfunctional isocyanate crosslinking agent (Coronate L, manufactured by NPU, Japan) was added to 100 parts by weight of the photocurable (meth) acrylate copolymer (B4) prepared in Production Example 2-4, 0.5 part by weight of a photopolymerization initiator (hydroxycyclohexyl Phenyl ketone, irgacure 184, and 0.2 parts by weight of Ciba Specialty Chemicals, Switzerland) were mixed to prepare a pressure-sensitive adhesive composition.

Comparative Example  2. Preparation of optical transparent pressure-sensitive adhesive composition

A pressure-sensitive adhesive composition was prepared by mixing 0.5 part by weight of a polyfunctional isocyanate crosslinking agent (Coronate L, manufactured by NPU, Japan) with respect to the acrylate copolymer (C1) weight part prepared in the above 3-1.

Example  6: Preparation of optical transparent pressure-sensitive adhesive film

Each of the optical transparent pressure sensitive adhesive compositions prepared in Examples 1 to 5 and Comparative Examples 1 and 2 was coated on a 50 탆 thick PET film coated with a silicone release agent to a thickness of 100 탆 after curing, (Using the optical transparent pressure-sensitive adhesive composition of Example 1), Example 6-2 (using the optical transparent pressure-sensitive adhesive composition of Example 2), and Example 6-3 (using the optical transparent pressure-sensitive adhesive of Example 3) (Using the optical transparent pressure-sensitive adhesive composition of Example 5), Example 6-5 (using the optical transparent pressure-sensitive adhesive composition of Example 5), Comparative Example 3-1 (Comparative Example 3-1) Sensitive adhesive composition of Comparative Example 3-2 (using the optical transparent pressure-sensitive adhesive composition of Comparative Example 2).

Example  7: The pressure-  Formed Of the laminate  Produce

The optical transparent pressure-sensitive adhesive films prepared in Examples 6-1, 6-2, 6-3, 6-4, 6-5, Comparative Examples 3-1, and 3-2 each embodiment is irradiated with light amount of 1000mJ / cm ² using a UV lamp (Fusion Co.) in the direction of laminating the pressure-sensitive adhesive layer and a release film on 100㎛ of the PET film (manufactured by Mitsubishi 100um PET) thickness using example 7-1 , Example 7-2, Example 7-3, Example 7-4, Example 7-5, Comparative Example 4-1, and Comparative Example 4-2 were prepared.

Example  8: Flexibility  For evaluation Hard coating  film/ Adhesive layer / PET Of the laminate  Produce

The laminate of Example 7-1, Example 7-2, Example 7-3, Example 7-4, Example 7-5, Comparative Example 4-1, and Comparative Example 4-2 was laminated on a 50 mm x And cut into a size of 100 mm. Then, the release PET film adhered to the pressure-sensitive adhesive layer of the cut laminate was peeled off, adhered onto the hard coating film for flexural evaluation prepared in Production Example 3 of 50 mm x 100 mm size, and autoclave , 5 atmospheric pressure) for about 20 minutes and cured for 24 hours under constant temperature and humidity conditions (23 ° C, 50% relative humidity) to obtain Examples 8-1, 8-2, 8-3, Hard coat film / pressure-sensitive adhesive layer / PET (100 占 퐉) laminate for evaluation of flexural properties according to Examples 8-4, 8-5, Comparative Examples 5-1 and 5-2.

Test Example : Evaluation of physical properties of optical transparent pressure-sensitive adhesive composition

One. Folding characteristic  evaluation

<Evaluation method>

Evaluation standard: IEC 62715

Evaluation equipment: Face-to-face unloaded U-folding tester (DLDMLH-FS)

Equipment maker: YUASA SYSTEM (Japan)

Evaluation conditions: -20 占 폚 / 10,000 times (bending such that the hard coating side is folded inward)

Examples 8-1, 8-2, 8-3, 8-4, 8-5, Comparative Example 5-1, and Comparative Example 5-2 prepared in Example 8 The hard coating film / adhesive layer / PET laminate for evaluation of flexibility was evaluated for folding properties according to the above evaluation method, and is shown in Table 1 below.

<Evaluation Criteria>

○: No defective modes such as bubbles, peeling, cracks were observed in the laminate

DELTA: A minute defective mode was visually visually observed in the laminate.

X: Bad mode clearly visible in the folded part of the laminate.

2. Evaluation of durability

(1) Evaluation of heat resistance

Examples 8-1, 8-2, 8-3, 8-4, 8-5, Comparative Example 5-1, and Comparative Example 5-2 prepared in Example 8 The hard coat film for evaluation of bendability / adhesive layer / PET laminate was allowed to stand at a temperature of 80 DEG C for 1,000 hours, and then the occurrence of bubbles or peeling was observed to evaluate heat resistance. The results are shown in Table 1 below.

<Evaluation Criteria>

◎: No bubble or peeling

○: Bubbles or peeling <5

?: 5 pieces? Bubbles or peeling <10 pieces

X: 10 pieces &lt; bubble &

(2) Humidity Durability  evaluation

Examples 8-1, 8-2, 8-3, 8-4, 8-5, Comparative Example 5-1, and Comparative Example 5-2 prepared in Example 8 The hard coating film for flexural evaluation / adhesive layer / PET laminate was allowed to stand at a temperature of 60 DEG C and a temperature of 90% RH for 1,000 hours, and then the occurrence of bubbles or peeling was observed. At this time, the sample was allowed to stand at room temperature for 24 hours immediately before the evaluation of the state of the specimen, and then the heat and humidity resistance was evaluated. The results are shown in Table 1 below.

<Evaluation Criteria>

◎: No bubble or peeling

○: Bubbles or peeling <5

?: 5 pieces? Bubbles or peeling <10 pieces

X: 10 pieces &lt; bubble &

3. Adhesion evaluation

Example 7-1, Example 7-2, Example 7-3, Example 7-4, Example 7-5, Comparative Example 4-1, and Comparative Example 4-2 prepared in Example 7 were conducted The laminate having the pressure-sensitive adhesive layer prepared in Example 5-1, Example 5-2, Example 5-3, Comparative Example 5-1, and Comparative Example 5-2 was cut to a size of 25 mm x 100 mm, . Then, the releasing PET film adhered to the pressure-sensitive adhesive layer was peeled off, and the laminate having the pressure-sensitive adhesive layer formed thereon was adhered to the alkali-free glass using a roller of 2 kg in accordance with JIS Z 0237. The alkali-free glass with the laminate was subjected to compression treatment for 20 minutes in an autoclave (50 ° C, 5 atmospheric pressure) and stored at room temperature and humidity (23 ° C, 50% relative humidity) for 24 hours to prepare samples. Thereafter, the adhesive agent was peeled from the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 180 degrees using a TA instrument (Texture Analyzer, manufactured by Stable Micro Systems, UK) Respectively.

[Table 1]

[Table 2]

As can be seen from the test results shown in Tables 1 and 2, the optical transparent pressure-sensitive adhesive compositions of Examples of the present invention were found to have excellent folding characteristics, heat resistance, heat resistance, and adhesion. Particularly, the folding properties were confirmed to be remarkably excellent as compared with the optical transparent pressure-sensitive adhesive compositions of the comparative examples.

Claims (13)

A) a photocurable (meth) acrylate copolymer; B) acrylate copolymers; And C) a photopolymerization initiator,
(A) the photocurable (meth) acrylate copolymer contains 95 to 99.9% by weight of a hydroxy group-containing acrylic copolymer and 0.1 to 5% by weight of an isocyanate group-containing (meth) acrylate monomer based on the total weight of the constituent units contained in the copolymer, Wherein the hydroxy group-containing acrylic copolymer and the isocyanate group-containing (meth) acrylate monomer form a urethane bond,
The hydroxy group-containing acrylic copolymer is obtained by copolymerizing 80 to 98% by weight of a linear or branched C ₄ to C ₁₂ alkyl acrylate monomer having a glass transition temperature of -70 to -50 ° C. based on the total weight of the monomers contained in the copolymer, (Meth) acrylate copolymer comprising 2 to 20% by weight of a C ₂ to C ₆ linear or branched alkyl acrylate monomer and having a weight average molecular weight of 500,000 to 2,000,000,
The acrylate copolymer of B) is prepared by copolymerizing 80 to 95% by weight of linear or branched alkyl acrylate monomer having ₄ to ₁₂ carbon atoms and 5 to 20% by weight of an adhesion promoting agent-containing polymerizable monomer based on the total weight of the monomers contained in the copolymer, , An acrylate copolymer containing no photo-crosslinkable functional group and having a weight average molecular weight of 10,000 to 100,000,
Wherein the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B) are contained in a weight ratio of 95: 5 to 70:30. The method according to claim 1,
C ₄ to C ₁₂ linear or branched alkyl acrylate monomers having a glass transition temperature of -70 to -50 ° C, which is used for producing the photocurable (meth) acrylate copolymer of A), are n-butyl acrylate butyl acrylate, t-butyl acrylate, sec-butyl acrylate, pentyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate and isononyl acrylate At least one monomer selected,
Hydroxy C ₂ -C ₆ linear or branched alkyl acrylate monomers include 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 5-hydroxypentyl acrylate and 6- Acrylate, and hydroxyhexyl acrylate. The method of claim 2,
C ₄ to C ₁₂ linear or branched alkyl acrylate monomers having a glass transition temperature of -70 to -50 ° C, which is used for producing the photocurable (meth) acrylate copolymer of A), are n-butyl acrylate And 2-ethylhexyl acrylate,
Wherein the hydroxy C ₂ -C ₆ linear or branched alkyl acrylate monomer is at least one monomer selected from 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate. The optical transparent pressure-sensitive adhesive composition according to claim 1, wherein the isocyanate group-containing (meth) acrylate monomer is isocyanato C ₁ -C ₁₀ alkyl (meth) acrylate. The optical transparent pressure-sensitive adhesive composition according to claim 4, wherein the isocyanate group-containing (meth) acrylate monomer is 2-isocyanatoethyl methacrylate. [2] The composition of claim 1, wherein the adhesion promoting agent-containing polymerizable monomer is a compound of Formula 1; A compound of formula 2; A compound of formula 3; A chemical of formula 4; A compound of formula 5; A compound of formula 6; A compound of formula 7; And a compound of the formula (8).
&Lt; Formula 1 >

(2)

(3)

&Lt; Formula 4 >

&Lt; Formula 5 >

(6)

&Lt; Formula 7 >

(8)

In the above formula (7), X is at least one selected from the group consisting of PF5, SbF6, mesylate (OMs), tosylate (OTs), triflate (OTf), bis (fluorosulfonyl) imide; FSI), and bis (trifluoromethylsulfonyl) imide (TFSI). The method of claim 1, wherein the C ₄ to C ₁₂ linear or branched alkyl (meth) acrylate monomers used to prepare the acrylate copolymer of B) are selected from the group consisting of n-butyl acrylate, t-butyl acrylate, sec At least one monomer selected from the group consisting of butyl acrylate, pentyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate and isononyl acrylate The photopolymerizable composition according to claim 1, wherein the C) photopolymerization initiator is an optical transparent pressure-sensitive adhesive composition comprising 0.1 to 5 parts by weight based on 100 parts by weight of the total content of the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B) Composition. The optical transparent pressure sensitive adhesive composition according to claim 1, wherein the optical transparent pressure sensitive adhesive composition further comprises 40 to 85 parts by weight of a solvent based on 100 parts by weight of the total content of the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B) Wherein the optical transparent pressure-sensitive adhesive composition is an optically transparent pressure-sensitive adhesive composition. The optical transparent pressure sensitive adhesive composition according to claim 1, wherein the optical transparent pressure sensitive adhesive composition comprises 0.02 to 5 parts by weight of a multifunctional crosslinking agent based on 100 parts by weight of the total content of the photocurable (meth) acrylate copolymer of A) and the acrylate copolymer of B) Lt; / RTI &gt; An optical transparent pressure-sensitive adhesive film produced by coating the optical transparency pressure-sensitive adhesive composition of claim 1 onto a transfer film. A flat panel display comprising an adhesive layer formed from the optical transparent pressure sensitive adhesive composition of claim 1. The method of claim 12,
Wherein the flat panel display device is a flexible display device.