KR20130101783A - Adhesive composition for optical use - Google Patents

Abstract

PURPOSE: An optical adhesive composition is provided to have low curing contraction while maintaining adhesion, to have uniform thickness, to prevent bleed-out, and to have excellent heat resistance, moisture resistance, and durability under a high temperature and high humidity environment. CONSTITUTION: An optical adhesive composition includes a polyfunctional urethane acrylate-based oligomer, a monofunctional (meth)acrylate-based monomer, a free-radical photoinitiator, and a block copolymer which contains polymethylmethacrylate and polybutylacrylate as a repeating unit and the glass transition temperature of which is 5,000-30,000. An adhesive film includes a transparent substrate film and an adhesive which is formed on one side of the transparent substrate film and is that the adhesive composition is cured.

Description

Optical adhesive composition {ADHESIVE COMPOSITION FOR OPTICAL USE}

The present invention relates to a pressure-sensitive adhesive composition for optics with less occurrence of hardening shrinkage while maintaining adhesive force and uniform thickness and no bleed out.

In general, a liquid crystal display device (LCD) includes a liquid crystal cell and a polarizing plate including liquid crystal, and an appropriate adhesive layer or an adhesive layer for bonding them should be used.

The pressure-sensitive adhesive layer (film) may be classified into a thin film type adhesive layer and a thick film type adhesive layer depending on the use of a solvent.

The double thick-film adhesive layer is generally prepared by photopolymerizing a composition containing an acrylate oligomer or a urethane acrylate oligomer.

However, the composition containing the acrylate oligomer has a problem that the curing process is too slow at the time of photopolymerization and the processability is low, and the composition containing the urethane acrylate oligomer has a fast curing process at the time of photopolymerization, but the physical properties of the adhesive layer such as adhesive force are lowered. There is a problem.

In addition, photopolymerization using a composition containing an oligomer having an acrylic functional group such as an acrylate oligomer and a urethane acrylate oligomer has a large curing shrinkage, resulting in uneven thickness of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive component moves to the surface to precipitate. There is a problem that a bleed out phenomenon occurs.

The present invention is to provide an optical pressure-sensitive adhesive composition that can fundamentally improve the bleed out phenomenon that hardening shrinkage occurs and the pressure-sensitive adhesive component moves to the surface while preserving physical properties (adhesive force) of the pressure-sensitive adhesive itself.

In order to achieve the above object, the present invention provides a monofunctional urethane acrylate oligomer, a monofunctional (meth) acrylate monomer, a free radical photoinitiator, and a repeating unit of polymethyl methacrylate and polybutyl acrylate and a glass transition temperature. It provides an optical pressure-sensitive adhesive composition comprising a block copolymer of 50 to 10 ℃.

Preferably, the glass transition temperature of the block copolymer may be -40 to 10 ℃.

The monofunctional urethane acrylate oligomer may have a weight average molecular weight of 5,000 to 30,000.

The monofunctional urethane acrylate oligomer may have a viscosity (25 ° C.) of 10,000 to 300,000 cPs.

30 to 80% by weight of the monofunctional urethane acrylate oligomer, 5 to 60% by weight of monofunctional (meth) acrylate monomer, 0.1 to 10% by weight of free radical photoinitiator, and the repeating unit is polymethyl methacrylate and butyl acrylate And it may include 10 to 35% by weight of the block copolymer having a glass transition temperature of -50 to 10 ℃.

In addition, the present invention may be an optical pressure-sensitive adhesive cured adhesive composition.

The present invention also relates to a transparent substrate film; It may be an adhesive film including the pressure-sensitive adhesive formed on one surface of the transparent base film.

The pressure-sensitive adhesive may have a thickness of 25 to 1000 mu m.

Optical pressure-sensitive adhesive composition according to the present invention has the advantage that there is little occurrence of hardening shrinkage while maintaining the adhesive force, the thickness is uniform and there is no bleed out (transition phenomenon, precipitation phenomenon).

In addition, the optical pressure-sensitive adhesive composition according to the present invention has an advantage of excellent durability, such as heat and moisture resistant heat under high temperature or high temperature and high humidity environment.

The present invention relates to a pressure-sensitive adhesive composition for optics with less occurrence of hardening shrinkage while maintaining adhesive force and uniform thickness and no bleed-out occurrence.

Hereinafter, the present invention will be described in detail.

The optical pressure-sensitive adhesive composition of the present invention is a monofunctional urethane acrylate oligomer, a monofunctional (meth) acrylate monomer, a free radical photoinitiator, and a repeating unit of polymethyl methacrylate and polybutyl acrylate and a glass transition temperature of -50. To block copolymers of 10 ° C.

The urethane acrylate oligomer is a component for imparting physical properties as an adhesive, and generally, a urethane acrylate oligomer is made of polyester polyol and polyether polyol. Among them, polyether polyol is preferred in order to have high molecular weight and low viscosity, and it is particularly preferable to prepare a urethane (meth) acrylate oligomer with polypropylene glycol having a molecular weight of 800 to 4,500 as a main chain.

Moreover, it is preferable that the urethane (meth) acrylate oligomer of this invention is a monofunctional urethane (meth) acrylate oligomer which is not polyfunctional. In the case of using a polyfunctional urethane (meth) acrylate oligomer, the tacky of the surface of the pressure-sensitive adhesive layer is reduced and the cohesive force is excessively high, so that the expression of the adhesive physical properties is not easy.

The monofunctional urethane (meth) acrylate oligomer is a polymer obtained by the reaction of a polypropylene glycol, an isocyanate compound and a hydroxyl group-containing (meth) acrylate monomer having a molecular weight of 800 to 4,500. Polypropylene glycol has an effect of controlling the viscosity of the pressure-sensitive adhesive composition to lower the hydrogen bond between the urethane bonds when the oligomerization containing a methyl group, it is advantageous in terms of cost and low cost.

It is preferable that polypropylene glycol has a molecular weight of 800-4,500. When the molecular weight is less than 800, the viscosity of the oligomer may be increased in the process of high molecular weight oligomer, and when the molecular weight is greater than 4,500, the polypropylene glycol portion, which is a soft segment (amorphous), is too large in the oligomer molecule. Can fall and the durability of heat and moisture resistance becomes weak.

The kind of isocyanate type compound is not specifically limited, For example, isophorone diisocyanate, 2, 4- toluene diisocyanate, 2, 6- toluene diisocyanate, 1, 4- butylene diisocyanate, 1, 6- hexamethylene diisocyanate, Lysine diisocyanate, trimethylhexamethylene diisocyanate, 2,2-bis-4'-propane isocyanate, 6-isopropyl-1,3-phenyldiisocyanate, bis (2-isocyanate ethyl) -fumarate, 1,6- Hexane diisocyanate, 4,4'- diphenylene diisocyanate, 3,3'- dimethylphenylene diisocyanate, 3,3'- dimethyl-4,4'- diphenylmethane diisocyanate, p-phenylenedi isocyanate, m- Phenylene diisocyanate, 1,4-naphthalene diisocyanate, 1,5-naphthalene diisocyanate, 1,4- xylene diisocyanate, 1,3- xylene diisocyanate, cyclopentylene-1,3-diisocyanate Y, 4,4'-dicyclohexylmethane diisocyanate, cyclohexene-1,4-diisocyanate, 4,4'-methylenebis (phenylisocyanate), 2,2-diphenylpropane-4,4'-di Isocyanate, azobenzene-4,4'-diisocyanate, tetramethylxylene diisocyanate, 1-chlorobenzene-2,4-diisocyanate or oligomers thereof and the like, and isophorone diisocyanate, 1,6- Hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, etc. are preferable. These can be used individually or in mixture of 2 or more types.

The kind of the hydroxy group-containing (meth) acrylate monomer is not particularly limited, and for example, hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxypentyl (meth) Acrylate, hydroxyhexyl (meth) acrylate, hydroxyethylene glycol (meth) acrylate, hydroxypropylene glycol (meth) acrylate, hydroxybutyl vinyl ether, and the like, among which hydroxyethyl (meth) ) Acrylates are preferred. These can be used individually or in mixture of 2 or more types.

The manufacturing method of a monofunctional urethane (meth) acrylate oligomer is not specifically limited, A conventional one-shot method, a prepolymer method, etc. can be used. For example, the one-shot method mixes polypropylene glycol, a (meth) acrylate monomer having a hydroxy group, and a primary alcohol, and then reacts the isocyanate compound with an excess of an isocyanate compound in an appropriate equivalent ratio, preferably in order to improve the reaction efficiency. It is a method of manufacturing a monofunctional urethane (meth) acrylate oligomer. In addition, the prepolymer method mixes polypropylene glycol and an isocyanate compound, reacts with an isocyanate group [-NCO] of the polypropylene glycol and an isocyanate compound to obtain a prepolymer having a urethane bond, and then has a (meth) acrylate having a hydroxy group thereon. A method of preparing a monofunctional urethane (meth) acrylate oligomer by reacting a solution in which a monomer and a primary alcohol are mixed in an equivalent ratio of 1: 1.

It is preferable that the number of urethane bonds of the monofunctional urethane (meth) acrylate oligomer is 3 to 15. When the number of urethane bonds is less than 3, it may be difficult to manufacture a uniform composition and the cohesion may be weakened, and when the number of the urethane bonds is greater than 15, the cohesion may be too high and the initial tackiness may be worsened. At this time, the number of urethane bonds can be adjusted in consideration of the molecular weight of polypropylene glycol and the weight average molecular weight of the monofunctional urethane (meth) acrylate oligomer to be prepared.

The weight average molecular weight of the monofunctional urethane (meth) acrylate oligomer affects the adhesion and viscosity. Usually, the smaller the weight average molecular weight, the lower the viscosity but the lower the adhesive strength. On the contrary, the larger the weight average molecular weight, the better the adhesive strength but the viscosity. Becomes higher. In the present invention, the weight average molecular weight is particularly preferably 5,000 to 30,000, more preferably 10,000 to 30,000. If the weight average molecular weight is less than 5,000, the viscosity is too low, the coating property is not good and it is difficult to obtain the effect of the use of the diluent monomer, if it is over 30,000, the viscosity is too high, poor handling.

In addition, the viscosity of the monofunctional urethane (meth) acrylate oligomer is preferably 10,000 to 300,000 cPs, more preferably 10,000 to 150,000 cPs. If the viscosity is less than 10,000 cPs it is difficult to control the appropriate coating viscosity using a diluent monomer, and if it is more than 300,000 cPs it may be difficult to control the adhesion and durability by using excessive diluent monomer to obtain the proper viscosity.

The monofunctional urethane (meth) acrylate oligomer is preferably contained in 30 to 80% by weight, more preferably 40 to 75% by weight in 100% by weight of the total pressure-sensitive adhesive composition. If the content is less than 30% by weight, the viscosity of the pressure-sensitive adhesive composition is poor, coating property is not good, if it is more than 80% by weight, the viscosity is high, the processability may be lowered, and may be difficult to apply for optical.

The (meth) acrylate monomer is a monomer having a functional group capable of crosslinking with a monofunctional urethane (meth) acrylate oligomer while controlling the viscosity of the pressure-sensitive adhesive composition that is solventless.

The kind of the monofunctional (meth) acrylate monomer is not particularly limited, and for example, n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acryl Latex, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, Pentyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-methylbutyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate , Isoamyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, octadecyl (meth) acrylate, isobornyl (meth) acrylate, 4-methyl-2-pentyl ( Meta) acrylate, dodecyl (meth) acrylate, 2-dodecylthio Ethyl (meth) acrylate, lauryl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl ( Meth) acrylate, hydroxybutyl (meth) acrylate, allyl (meth) acrylate, stearyl (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, acrylo Ilmorpholine etc. are mentioned. These can be used individually or in mixture of 2 or more types.

In addition, bifunctional (meth) acrylate monomers, trifunctional (meth) acrylate monomers, or mixtures thereof may be mixed with a monofunctional (meth) acrylate monomer within a range that does not impair the effects of the present invention. have. As the bifunctional (meth) acrylate monomer, 1,3-butanedioldi (meth) acrylate, 1,4-butanedioldi (meth) acrylate, 1,6-hexanedioldi (meth) acrylate, ethylene glycol di (Meth) acrylate, bisphenol A- ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (Meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dicyclopentanyldi (meth) acrylate, caprolactone modified dish Clopentenyl di (meth) acrylate, ethylene oxide modified phosphate di (meth) acrylate, bis (2-hydroxyethyl) isocyanurate di (meth) acrylate, di (acryloxyethyl) isocyanu Acrylate, allylated cyclohexyldi (meth) acrylate, dimethyloldicyclopentanedi (meth) acrylate, ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecanedimethanol (meth) acrylate, neopentyl Glycol modified trimethylolpropanedi (meth) acrylate, adamantanedi (meth) acrylate, and the like. As the trifunctional (meth) acrylate monomer, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tree (Meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, glycerol Tri (meth) acrylate etc. are mentioned. These can be used individually or in mixture of 2 or more types.

The monofunctional (meth) acrylate monomer is preferably included at 5 to 60% by weight in 100% by weight of the total pressure-sensitive adhesive composition, more preferably 10 to 50% by weight, most preferably 20 to 45% by weight. It is good. If the content is less than 5% by weight, the curing rate may be lowered, and if it is more than 60% by weight, curing shrinkage may occur seriously and the coatability may be reduced.

A free radical photoinitiator is a component for fully advancing hardening of the surface as well as the inside of the coated adhesive composition, If it is a thing known in the art, the kind will not be specifically limited. Specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, hydroxydimethylacetophenone, dimethylaminoacetophenone, Dimethoxy-2-phenylacetophenone, 3-methylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 4-chronolocetophenone, 4, 4-dimethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4-hydroxycyclophenylketone, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4 -(Methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenyl Benzophenone, 4,4-diaminobenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-meth Tyl thioxanthone, 2-ethyl thioxanthone, 2-chloro thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyl dimethyl ketal, diphenyl ketone benzyl dimethyl ketal, acetophenone Dimethyl ketal, p-dimethylaminobenzoic acid ester, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, fluorene, triphenylamine, carbazole and the like. Further, commercially available products such as Darocur 1173, Irgacure 184, Irgacure 907, Irgacure 1700 and TPO-L (BASF) can also be used. These can be used individually or in combination of 2 or more types.

The free radical photoinitiator is preferably included in 0.1 to 10% by weight in 100% by weight of the total pressure-sensitive adhesive composition, more preferably 0.1 to 5% by weight. When the content is less than 0.1% by weight, the curing rate may be slow and sufficient curing may be difficult to proceed, and when the content is more than 10% by weight, the molecular weight of the polymer to be photopolymerized may be reduced, thereby reducing durability.

Block copolymers are those in which polymethyl methacrylate repeating units and polybutyl acrylate repeating units are irregular or regularly polymerized.

The polymethyl methacrylate (PMMA) has high transparency, crystallinity, and glass transition temperature (Tg) of about 100 to 120 ° C., which makes it difficult to apply a general adhesive. In addition, butyl acrylate of polybutyl acrylate (BA) is a monomer commonly used as an acrylic pressure-sensitive adhesive, the glass transition temperature (Tg) is about -50 to -60 ℃ degree and has the adhesiveness.

The polymethyl methacrylate and polybutyl acrylate are heterogeneous and have surface energy values of 40 to 42 mN / m (polymethyl methacrylate) and 24 to 26 mN / m (polybutyl acrylate), respectively. There is a problem that haze occurs due to the difference in the surface energy value. Therefore, the present invention performs copolymerization to suppress the generation of haze.

The present invention is characterized in that it contains a block copolymer polymerized by mixing the two repeating units in a ratio at which no haze occurs. The polymerization ratio of these two repeat units can be inferred by the glass transition temperature (Tg) of the polymerized block copolymer.

That is, the glass transition temperature of the block copolymer is a property range obtained by controlling the polymerization ratio of the repeating unit to a specific range, and haze generation is suppressed through the control of the polymerization ratio.

In general, a method of inferring a mixing ratio using a glass transition temperature is as follows. The method for estimating the synthetic glass transition temperature of the acrylic copolymer can be calculated by the formula of 1 / Tg = W1 / Tg1 + W2 / Tg2, called The Fox's Equation.

In this case, Tg is the glass transition temperature of the synthesized copolymer, W1 and W2 are the weight ratio of monomer 1 and monomer 2 used in the synthesis, respectively, Tg1 and Tg2 is the glass transition temperature of monomer 1 and glass of monomer 2 used in the synthesis. Transition temperature. In addition, the glass transition temperature is calculated by K (Kelvin, absolute temperature), and then converted to ℃ (Celsius).

The copolymer has an appropriate viscosity that is easy to mix, and the glass transition temperature (Tg) of the synthesized copolymer is preferably -50 to 10 ° C. in order to help adhesion. To obtain such Tg value, polymethyl methacrylate and poly The proportion of butyl acrylate is preferably 50:50 to 10:90 by weight. More preferably, the glass transition temperature (Tg) of the copolymer is -40 to 10 ° C.

Examples of the block copolymer include Kuraray TL3320 Kuraiti, LA1114 Kuraiti, and the like. They can maintain physical properties as adhesives without any haze on the optical. In addition, it is excellent in solubility, and physical crosslinking is formed by the polymethyl methacrylate and the polybutyl acrylate expressing an entanglement effect without the need for a separate crosslinking agent. By such physical crosslinking, the bleed out phenomenon can be suppressed.

The adhesive composition of the present invention can be cured to form an adhesive. In addition, transparent substrate film; An adhesive film may be formed by including the adhesive formed on one surface of the transparent base film.

The pressure-sensitive adhesive may have a thickness of 25 to 1000 mu m.

The transparent base film is not particularly limited as it is excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like.

The curing is used in the art, but is not particularly limited, photocuring using ultraviolet light is generally.

The light source in the polymerization using ultraviolet rays has a light emission distribution of 400 nm or less, preferably 150 to 400 nm, and more preferably 200 to 380 nm. The light source may be a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, , A black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

The intensity of the light irradiation can be appropriately adjusted according to the required physical properties of the pressure-sensitive adhesive, the amount of accumulated light useful for the activity of the free radical photoinitiator is preferably 10 to 5000mJ / ㎠, more preferably 200 to 800mJ / ㎠. It is preferable to have an appropriate curing reaction time within the above range, and do not cause a decrease in cohesion, yellowing or deterioration of the support of the cured product produced by heat radiated from the lamp and exotherm during the polymerization reaction.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Preparation example: Urethane (meth) acrylate oligomer

A 10 L four-necked flask equipped with a thermometer and a stirring device and capable of refluxing nitrogen was immersed in an oil bath, and 3038 g of polypropylene glycol (Sannix PP-4000, Samyang Chemical) with a molecular weight of 4,000 was placed in this flask. 337 g and 0.3 g of dibutyl tin dilaurate as urethane-forming catalysts were added, followed by stirring at a reaction temperature of 60 ° C. for 2 hours to obtain a urethane prepolymer. After the reaction temperature was lowered to 40 ° C., 0.3 g of dibutyltin dilaurate, a urethaneization catalyst, and 0.5 g of 2,6-t-butyl-4-methylphenol (BHT), a polymerization inhibitor, were added thereto. A mixture of 56 g of butanol and 88 g of 2-hydroxyethyl acrylate (Osaka Organic Chemical Co., Ltd.) was reacted with a slow dropwise addition for 30 minutes. The reaction temperature was then raised to 70 ° C. and stirred to obtain a monofunctional urethane acrylate oligomer having a weight average molecular weight of 26,600.

Example 1

(1) pressure-sensitive adhesive composition

58% by weight of the urethane (meth) acrylate oligomer of Preparation Example 1, 15% by weight of acryloyl morpholine and 15% by weight of isobornyl acrylate, 2.0% by weight of photopolymerization initiator Tarocure 1173 (BASF), polymethyl methacrylate A pressure-sensitive adhesive composition was prepared by mixing 10 wt% of a block copolymer (PMMA) with a polybutyl acrylate (BA) (glass transition temperature of 10 ° C., manufactured by TL3320, Kurarith Co., Ltd.).

(2) adhesive film

On one transparent film coated with a silicone release agent on a polyethylene terephthalate (PET) film, the pressure-sensitive adhesive composition of (1) was coated so as to have a thickness of 300 μm after curing, followed by ultraviolet light (600 mJ / cm 2 at a speed of 4 m / min). ) Was investigated and completely cured. Thereafter, by bonding the same transparent film on the cured pressure-sensitive adhesive layer to prepare an adhesive film.

Examples 2-6 and Comparative Examples 1-4

To carry out the same as in Example 1, to prepare a pressure-sensitive adhesive film using the composition of Table 1.

division Monofunctional urethane acrylate oligomer Monofunctional (meth) acrylate monomer Free radical photoinitiator polymer A-1 A-2 B-1 B-2 B-3 B-4 Example 1 58 15 15 2 10 - - - Example 2 58 15 15 2 - 10 - - Example 3 48 15 15 2 - 20 - - Example 4 38 15 15 2 - 30 - - Example 5 33 15 15 2 - 35 - - Example 6 38 15 15 2 10 20 - - Comparative Example 1 68 15 15 2 - - - - Comparative Example 2 48 15 15 2 - - 20 - Comparative Example 3 48 15 15 2 - - - 20 Comparative Example 4 48 15 15 2 - - 10 10 A-1: Isobonylacrylate
A-2: Acrylomorpholine
B-1: PMMA / BA block copolymer, glass transition temperature 10 ℃, TL3320 Kuraiti products (solid), Kuraray
B-2: PMMA / BA block copolymer, glass transition temperature -35 ° C, LA1114 Kurarith product (liquid), Kurrayei
B-3: PMMA homopolymer, glass transition temperature 104 캜, solid phase
B-4: BA homopolymer, glass transition temperature -50 ° C, SY-061 product, Negisa
Free radical photoinitiator: Darocure 1173, BASF

Test Example

Physical properties of the pressure-sensitive adhesive composition and pressure-sensitive adhesive film prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 2 below.

1. Adhesion (N / 25㎜)

The prepared pressure-sensitive adhesive film was cut into a size of 25 mm × 250 mm using a super cutter, and then the release film was peeled off, bonded to a glass plate, and a specimen was prepared. The prepared specimen was fixed to a universal testing machine (UTM), and then peeled at 180 ° at a speed of 300 m / min to measure adhesion to glass. At this time, the adhesive force means the adhesive force of the surface irradiated with ultraviolet rays.

2. Adhesion durability (heat and moisture resistance)

The prepared pressure-sensitive adhesive film was cut to A4 size using a super cutter, and one transparent film was peeled off, and then bonded to a glass plate. The conjugate was treated in an autoclave for 20 minutes at 50 ° C. and 5 atmospheres to prepare a specimen. Heat-resistant durability was left for 100 hours in the specimen at 80 ℃ oven, heat-resistant durability was left for 100 hours in 60 ℃ and 90% RH oven, and then whether bubbles or peeling occurred on the bonding surface of the glass plate and the adhesive layer It was observed visually and evaluated based on the following criteria.

<Evaluation Criteria>

(Circle): There is no bubble and peeling phenomenon in a joining surface.

(Triangle | delta): Some bubble or peeling phenomenon exists in a joining surface.

X: There exist many bubbles and peeling phenomenon in a joining surface.

3. Haze

The prepared adhesive sheet was left to stand in -40 degreeC oven and 80 degreeC oven, respectively for 100 hours, and haze was measured (Equipment: HZ-02 of SUGA, Japan).

4. Hardening shrinkage

The pressure-sensitive adhesive composition was coated to have a thickness of 300 μm, and then cured by ultraviolet irradiation at a speed of 4 m / min (600 mJ / cm 2) using an ultraviolet irradiator. The cured coating layer surface was visually confirmed in reflection mode under fluorescent lamps.

<Evaluation Criteria>

(Double-circle): When shrinkage is not seen in reflection mode.

(Circle): When the shape of the fluorescent light source is inconsistent or the degree of shrinkage is weak in reflection mode.

X: The shrinkage degree is clearly seen in the reflection mode.

division Adhesion (N / 25mm) Hayes Adhesive durability Hardening shrinkage Example 1 18.5 0.4 ○ ○ Example 2 20.7 0.4 ○ ○ Example 3 22.3 0.5 ○ ◎ Example 4 25.6 0.5 ○ ◎ Example 5 24.1 0.6 ○ ◎ Example 6 21.2 0.4 ○ ◎ Comparative Example 1 14.5 0.4 ○ × Comparative Example 2 - - - - Comparative Example 3 4.2 0.6 × ○ Comparative Example 4 14.5 10.2 × ○

As shown in Table 2, the optical pressure-sensitive adhesive composition of Examples 1 to 6 according to the present invention is excellent in adhesive strength and less hardening shrinkage than the Comparative Examples 1, 3 and 4, has a low haze value and durability (heat resistance and heat resistance). Moist heat) was confirmed to be excellent.

In Comparative Example 2, the physical properties of the solid-state PMMA were not dissolved in the state of the composition in which the oligomer and the monomer were mixed.

Claims (8)

Monofunctional urethane acrylate oligomer, monofunctional (meth) acrylate monomer, free radical photoinitiator, and block copolymer having repeating units of polymethyl methacrylate and polybutyl acrylate and a glass transition temperature of -50 to 10 ° C Optical pressure-sensitive adhesive composition comprising a.
The optical adhesive composition of claim 1, wherein the block copolymer has a glass transition temperature of -40 to 10 ° C.
The optical pressure-sensitive adhesive composition of claim 1, wherein the monofunctional urethane acrylate oligomer has a weight average molecular weight of 5,000 to 30,000.
The optical pressure-sensitive adhesive composition of claim 1, wherein the monofunctional urethane acrylate oligomer has a viscosity (25 ° C) of 10,000 to 300,000 cPs.
The method according to claim 1, wherein 30 to 80% by weight of the monofunctional urethane acrylate oligomer, 5 to 60% by weight of the monofunctional (meth) acrylate monomer, 0.1 to 10% by weight of the free radical photoinitiator, and the repeating unit is polymethyl meta Optical adhesive composition comprising 10 to 35% by weight of a block copolymer having a acrylate and butyl acrylate and a glass transition temperature of -50 to 10 ℃.
Optical adhesive which the adhesive composition of any one of Claims 1-5 hardened | cured.
A transparent base film;
Adhesive film comprising the pressure-sensitive adhesive of claim 6 formed on one surface of the transparent base film.
The pressure-sensitive adhesive film of claim 7, wherein the pressure-sensitive adhesive has a thickness of 25 to 1000㎛.