KR20130019894A - Adhesive composition for optical use - Google Patents

Abstract

PURPOSE: An optical adhesive composition is provided to have excellent adhesion and gel fraction while maintaining adhesion and to maintain uniform thickness. CONSTITUTION: An optical adhesive composition comprises: 25-80 weight% of a monofunctional urethane acrylate-based oligomer with one or more hydroxy group(-OH) at the end thereof; 15-70 weight% of an acrylate-based monomer; and 0.1-5 weight% of a free-radical. The monofunctional urethane acrylate-based oligomer comprises a backbone, an ether backbone, and a mixed backbone thereof and has a weight-average molecular weight of 5,000-50,000. The acrylate-based monomer has 1-4 functionalities.

Description

Optical adhesive composition {ADHESIVE COMPOSITION FOR OPTICAL USE}

The present invention relates to an optical pressure-sensitive adhesive composition having excellent durability due to less curing shrinkage while maintaining physical properties of the pressure-sensitive adhesive itself, uniform thickness, and improved adhesion and gel fraction.

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 of low processability because the curing process is too slow during photopolymerization, and the composition containing the urethane acrylate oligomer is faster than the acrylate oligomer although the curing process is quick during photopolymerization. There exists a problem that physical properties, such as adhesive force, fall.

The composition containing the urethane acrylate oligomer has been proposed to use a monofunctional urethane acrylate oligomer to improve the adhesive force. However, since the gel fraction is lowered because the crosslinking density and cohesive force of the composition are low, there is a disadvantage in that durability such as heat and moisture resistance is low.

In addition, the composition containing a bifunctional urethane acrylate oligomer has a high gel fraction, but has a relatively low adhesive strength.

The present invention is to provide a pressure-sensitive adhesive composition for optics excellent at the same time while maintaining the physical properties of the pressure-sensitive adhesive itself.

In addition, the present invention is to provide a pressure-sensitive adhesive composition for optics is less thickness hardening shrinkage occurs.

In the present invention, the pressure-sensitive adhesive composition containing at least one hydroxyl group (-OH) as a reactive end group of the monofunctional urethane acrylate oligomer is induced by hydrogen bonding between the oligomers by the hydroxyl group (-OH), thereby increasing the gel fraction at the same time as the adhesive force. It has been found to be excellent to complete the present invention.

Therefore, the present invention is a monofunctional urethane acrylate oligomer having at least one hydroxyl group (-OH) at the terminal; Acrylate monomers; And it provides an optical pressure-sensitive adhesive composition containing a free radical initiator.

The monofunctional urethane acrylate oligomer may be one or two hydroxyl groups (-OH) at the terminal.

The monofunctional urethane acrylate oligomer may include an ester main chain, an ether main chain or a main chain of a mixed structure thereof.

The monofunctional urethane acrylate oligomer may have a weight average molecular weight of 5,000 to 50,000.

The acrylate monomer may be 1 to 4 functional.

25 to 80% by weight of a monofunctional urethane acrylate oligomer having at least one hydroxy group (-OH) at the terminal; 15 to 70% by weight of acrylate monomers; And 0.1 to 5% by weight free radical initiator.

In addition, the present invention provides a pressure-sensitive adhesive of the pressure-sensitive adhesive composition.

In addition, the present invention is a transparent substrate film; It provides an adhesive film comprising 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㎛.

The pressure-sensitive adhesive composition of the present invention is excellent in adhesive strength and gel fraction at the same time, and excellent in durability, such as heat and moisture resistance. The adhesive force is excellent not only for plastic materials but also for inorganic materials.

In addition, the pressure-sensitive adhesive composition of the present invention is less likely to be cured shrinkage is possible to maintain a uniform thickness.

In addition, since the pressure-sensitive adhesive composition of the present invention does not contain a separate solvent, it is possible to manufacture a thick-film pressure-sensitive adhesive film.

The present invention relates to an optical pressure-sensitive adhesive composition having excellent durability due to less curing shrinkage while maintaining physical properties of the pressure-sensitive adhesive itself, uniform thickness, and improved adhesion and gel fraction.

Hereinafter, the present invention will be described in detail.

Optical pressure-sensitive adhesive composition of the present invention is a monofunctional urethane acrylate oligomer having at least one hydroxyl group (-OH) at the terminal; Acrylate monomers; And free radical initiators.

The urethane acrylate oligomer comprises a reactive end group and a urethane bond group in a main chain component such as polyether, polyester and polycarbonate.

The present invention necessarily includes at least one hydroxyl group (—OH), preferably one or two reactive groups.

The hydroxyl group (-OH) formed at the end forms a hydrogen bond between the urethane acrylate oligomers, so that the crosslinking density of the pressure-sensitive adhesive composition is increased, thereby increasing the gel fraction. The elevated gel fraction exhibits a range similar to that of a pressure-sensitive adhesive composition containing a conventional bifunctional urethane acrylate oligomer, which makes the pressure-sensitive adhesive composition durable (such as heat and moisture resistance).

In addition, the present invention is excellent in adhesive strength because the acrylic equivalent by the mono-light urethane acrylate oligomer is high, the internal stress of the pressure-sensitive adhesive is reduced and has excellent TACK (TACK).

That is, the present invention provides a pressure-sensitive adhesive composition having a high adhesive force and a gel fraction by including one hydroxyl group (-OH) as a reactive end group of the monofunctional urethane acrylate oligomer.

The main chain component is preferably polyether in terms of low viscosity and low cost.

Polyethers consist primarily of polymeric diols or polyols and hydroxy acid components, and polyols suitable for use include polyether diols, hydrocarbon diols, polycarbonate diols, polyacrylate polyols (hydroxy functional acrylic polymers), polycaprolactone Diols and the like. These polyols can be used individually or in combination of 2 or more.

The method of polymerizing each structural unit of the polyol is not particularly limited, but block polymerization or graft polymerization may be used.

The polyether diol is obtained by ring-opening copolymerization of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, polydecamethylene glycol, two or more ion-polymerized cyclic compounds, and the like. Can lose.

The ion-polymerized cyclic compound may be, for example, ethylene oxide, propylene oxide, butene-1-oxide, isobutene oxide, 3,3'-bischloromethyloxetane, tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, dioxane, trioxane, tetraoxane, cyclohexene oxide, styrene oxide, epichlorohydrin, glycidyl methacrylate, allyl glycidyl ether, allyl glycidyl carbonate, butadiene monoxide Cyclic ethers such as isoprene monoxide, vinyl oxetane, vinyltetrahydrofuran, vinyl cyclohexene oxide, phenyl glycidyl ether, butyl glycidyl ether and glycidylbenzoate and the like.

Specific examples of the polyether diol obtained by ring-opening copolymerization of two or more forms of such ion-polymerized cyclic compounds include tetrahydrofuran and propylene oxide; Tetrahydrofuran and 2-methyltetrahydrofuran; Tetrahydrofuran and 3-methyltetrahydrofuran; Tetrahydrofuran and ethylene oxide; Propylene oxide and ethylene oxide; And copolymers obtained by the combination of ethylene oxide and butene-1-oxide, tertiary copolymers obtained by the combination of tetrahydrofuran, ethylene oxide and butene-1-oxide.

In addition, one of the ion-copolymerized cyclic compounds described above and cyclic imines such as ethylene imine; cyclic lactones such as β-propiolactone and glycolic acid lactide; Or polyether diol obtained by ring-opening copolymerization of dimethylcyclopolysiloxane can also be used. The ring-opening copolymer of such ion-polymerized cyclic compounds may be random copolymers or block copolymers.

In consideration of the improvement in adhesive force and gel fraction, the mono- photoactive urethane acrylate oligomer of the present invention preferably has a weight average molecular weight of 5,000 to 50,000 and more preferably a weight average molecular weight of 7,000 to 35,000.

In addition, when the weight average molecular weight is less than 5,000, the durability may be lowered. When the weight average molecular weight is greater than 50,000, the viscosity may increase, resulting in a decrease in workability and low uniformity of thickness, thereby causing problems in durability.

The monofunctional urethane acrylate oligomer contains 25 to 80% by weight based on the total amount of the pressure-sensitive adhesive composition (100% by weight), and when the content is less than 25% by weight, the content of the acrylate monomer is increased to increase the curing shrinkage. It may occur and if the amount exceeds 80% by weight there is a problem that the degree of curing is lowered.

The acrylate-based monomers impart durability to the film including the pressure-sensitive adhesive composition and maintain viscoelasticity, and serve to improve the coatability of the composition by controlling the viscosity.

As the acrylate monomer, 1 to 4 functional acrylic monomers may be used. Specific examples include ethyl acrylate, methyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, butyl acrylate, and isobutyl acrylate. , Allyl methacrylate, 2-ethoxyethyl (meth) acrylate, isodecyl (meth) acrylate, 2-dodecylthioethyl methacrylate, octyl acrylate, isooctyl acrylate, 2-methoxyethyl acryl Rate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, stearyl (meth) Acrylate, tetraperfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, octadecyl methacrylate, isobornyl (meth) acrylate, tetrahydrofuryl a A monofunctional monomer such as a relay agent, one know acryloyl morpholine; 1,3-butanedioldi (meth) acrylate, 1,4-butanedioldi (meth) acrylate, 1,6-hexanedioldi (meth) acrylate, ethylene glycoldi (meth) acrylate, bisphenol A-ethylene Glycol diacrylate, 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 dicyclopentenyldi (meth) acrylate, ethylene oxide modified phosphoric acid Di (meth) acrylate, bis (2-hydroxyethyl) isocyanurate di (meth) acrylate, di (acryloxyethyl) isocyanurate, allylated cyclohexyldi (meth) acrylate Difunctional monomers such as hydrate, dimethylol dicyclopentanediacrylate, ethylene oxide modified hexahydrophthalic acid diacrylate, tricyclodecane dimethanol acrylate, neopentyl glycol modified trimethylolpropane diacrylate, adamantane diacrylate ; Trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane Trifunctional monomers such as tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, and glycerol tri (meth) acrylate ; Tetrafunctional monomers such as diglycerin tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, and ditrimethylolpropane tetra (meth) acrylate; and the like, and these may be used alone or in combination of two or more thereof. Can be.

The acrylate monomer is preferably 15 to 70% by weight, preferably 20 to 50% by weight, based on the total content of the pressure-sensitive adhesive composition (100% by weight), when the content is less than 15% by weight, the curing rate is low or the storage modulus is low. This may be too low to cause cohesive failure, and if it exceeds 70% by weight, there is a serious hardening shrinkage may have a problem in coatability.

The free radical photoinitiator plays a role of sufficiently advancing the internal and surface hardening of the pressure-sensitive adhesive, and the type is not particularly limited as long as it is known in the art.

Specific examples of the free radical photoinitiator include 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-chronolo Acetophenone, 4,4-dimethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4-hydroxycyclophenylketone, 1-hydroxycyclohexylphenylketone, 2-methyl -1- [4- (methylthio) phenyl] -2-morpholino-propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzo Phenone, p-phenylbenzophenone, 4,4-diaminobenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t Butyl Ant Quinone, 2-aminoanthraquinone, 2-methyl thioxanthone, 2-ethyl thioxanthone, 2-chlorothioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyldimethyl Ketal, diphenyl ketone benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, fluorene, triphenylamine, carbazole and the like. have. Moreover, as a commercially available product, brand names Darocur 1173, Igacure 184, Igacure 907, Igacure-1700 (Ciba company), etc. can also be used. These can be used individually or in combination of 2 or more types.

The free radical photoinitiator may be used in an appropriate range in consideration of radiation characteristics, strength, content of each component, and the like, and may be included in an amount of 0.1 to 5 wt% based on the total amount of the adhesive composition (100 wt%).

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㎛.

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.

In the polymerization using ultraviolet rays, the light source has a light emission distribution having a wavelength of 400 nm or less, preferably 150 to 400 nm, more preferably 200 to 380 nm. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, and a chemical lamp , Black light lamps, microwave excited mercury lamps and metal halide lamps.

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 1500mJ / ㎠. 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.

Example 1

(1) pressure-sensitive adhesive composition

Monofunctional urethane acrylate oligomer (trade name DFCN-27, Negami Chemical, weight average molecular weight = 30,000, ether main chain, propylene glycol introduced into the reactive terminal group, the number of hydroxy groups (-OH) at the terminal: 68), The pressure-sensitive adhesive composition was prepared by mixing 30% by weight of isobornyl acrylate and 2% by weight of a free radical photoinitiator (Ciba, Darocur-1173) as an acrylate monomer.

(2) Preparation of adhesive film

The pressure-sensitive adhesive composition prepared in (1) was applied on a transparent base film coated with a silicone release agent to have a thickness of 300 μm, and the same transparent base film was laminated thereon, followed by a speed of 4 m / min (600 mJ / cm 2) It was irradiated and completely cured to form an adhesive.

Example 2-6 and Comparative Example 1-2

It carried out similarly to Example 1, but the composition of each component was used as shown in Table 1 below.

division
(weight%) Monofunctional urethane acrylate oligomer Bifunctional urethane acrylate oligomer Acrylate
Monomer Free radical initiator A-1 A-2 A-3 B-1 B-2 B-3 Example 1 68 - - - 30 - - 2 Example 2 68 - - - 28 2 - 2 Example 3 68 - - - - - 30 2 Example 4 58 - - - 40 - - 2 Example 5 40 - - - 58 - - 2 Example 6 - 68 - - 30 - - 2 Comparative Example 1 - - 68 - 30 - - 2 Comparative Example 2 - - - 68 30 - - 2 A-1: Brand name DFCN-27, Negami chemistry, Weight average molecular weight (Mw) = 30,000, Ether main chain, Monofunctional urethane acrylate, Propylene glycol is introduce | transduced into a reactive terminal group, The number of terminal hydroxyl groups (-OH): 1 dog
A-2: Brand name DFCN-28, Negami chemistry, Weight average molecular weight (Mw) = 30,000, Ether main chain, Monofunctional urethane acrylate, Glycerol is introduce | transduced into a reactive terminal group, The number of terminal hydroxyl groups (-OH): 2
A-3: trade name DFCN-5, Negami Chemical, weight average molecular weight (Mw) = 30,000, ether main chain, monofunctional urethane acrylate, butanol introduced into the reactive terminal group, the number of terminal hydroxyl groups (-OH): 0
Bifunctional urethane acrylate oligomer: trade name DFCN-6, negative chemical, weight average molecular weight (Mw) = 35,000, ether main chain, the number of hydroxyl groups (-OH) at the terminal: 0,
B-1: Isobonylacrylate
B-2: trimethylolpropane triacrylate
B-3: hydroxypropyl acrylate
Free radical photoinitiator: Ciba, Darocur-1173

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 / 25mm)

① Glass adhesion

After peeling off the base film coated with a release agent laminated on the adhesive film, the PET base film was not laminated. The adhesive sheet was cut into a size of 25 mm × 250 mm using a super cutter, bonded to glass, fixed to an autograph, and then peeled by 180 ° PEEL at a speed of 300 m / min to measure adhesive force.

② Polyethylene terephthalate (PET) film adhesion

PET film was attached to the glass using a double-sided tape to prepare a glass to which the PET film adhered. After peeling the base film coated with the release agent on the prepared adhesive film, it was laminated on the PET film. The adhesive sheet was cut into a size of 25 mm × 250 mm using a super cutter, bonded to a PET film-attached glass, and then fixed to an autograph, and then peeled by 180 ° PEEL at a speed of 300 m / min.

2. Gel fraction

The pressure sensitive adhesive sheet was cut into a size of about 8 cm x 8 cm, bonded to a metal mesh of SUS304 of about 10 cm x 10 cm, and the weight thereof was Wm. The weight of the adhesive sheet bonded to the metal mesh was measured and referred to as Ws. Thereafter, folded four times as if the pressure-sensitive adhesive was wrapped with a stapler to measure the weight, the weight was Wb. The stapler was fixed in a glass container, 60 ml of ethyl acetate was added thereto, and the mixture was stored at room temperature for 3 days. The metal mesh was taken out of the glass container, dried at 100 ° C. for 2 hours, and the weight thereof was determined as Wa to calculate the gel fraction by the following Equation 1.

3. Heat resistance

After peeling off the base film coated with the release agent laminated on the adhesive film, it was laminated on the unreleased PET film. The pressure-sensitive adhesive sheet was cut into A4 size using a super cutter, bonded to glass, and then treated in an autoclave for 20 minutes at 50 ° and 5 atmospheres, and then left in an 80 ° heat oven for 100 hours.

<Evaluation Criteria>

(Double-circle): There is no defect, such as air bubble, after heat resistance evaluation.

○: After the heat resistance evaluation, less than 10 bubbles of less than 1 μm were generated on the outside.

(Triangle | delta): More than 10 bubbles of 1 micrometer or less generate | occur | produce in the outer side after heat-resistant evaluation.

X: Bubbles and lifting are severe after heat resistance evaluation.

4. Moisture and heat resistance

After peeling off the base film coated with the release agent laminated on the adhesive film, it was laminated on the unreleased PET film. The pressure-sensitive adhesive sheet was cut into A4 size using a super cutter, bonded to glass, and then treated in an autoclave for 20 minutes at 50 ° and 5 atmospheres, and then left for 100 hours in a 60 ° and 90 RH% moisture resistant oven.

<Evaluation Criteria>

(Double-circle): There is no defect, such as air bubble, after heat-and-moisture heat evaluation.

(Circle): Less than 10 bubbles of less than 1 micrometer generate | occur | produce in the outer side after evaluating moisture-heat.

(Triangle | delta): More than 10 bubbles of 1 micrometer or less generate | occur | produce in the outer side after evaluation of heat-and-moisture heat.

X: The bubble and the generation | occurrence | production of a float are severe after heat-and-moisture evaluation.

5. Hardening shrinkage

The prepared pressure-sensitive adhesive composition was coated to have a thickness of 300 μm, and then irradiated with UV at a speed of 600 mJ / cm 2 using an ultraviolet irradiator to cure it. The hardened coating layer surface was visually observed, and the results were evaluated based on the following criteria.

<Evaluation Criteria>

(Double-circle): Hardening shrinkage does not occur at all. The surface is uniform and clean.

(Circle): Hardening shrinkage generate | occur | produces but there is no problem in appearance. The surface is generally uniform and clean.

X: Problems with appearance due to curing shrinkage. Uneven surface and contamination (hardening of hardening).

division Adhesion (N / 25㎜) Gel fraction
(weight%) durability Hardening shrinkage Glass PET film Heat resistance Moisture and Heat Resistance Example 1 12 10 88 ◎ ◎ ◎ Example 2 10 10 93 ◎ ◎ ◎ Example 3 10 8 87 ◎ ◎ ○ Example 4 11 12 89 ◎ ◎ ◎ Example 5 12 10 88 ○ ◎ ◎ Example 6 10 8 91 ○ ◎ ◎ Comparative Example 1 17 13 68 × × × Comparative Example 2 One 0.5 92 × × ◎

As shown in the above table, when the pressure-sensitive adhesive was formed by using an oligomer having a hydroxyl group introduced at the end, as shown in Examples 1 to 6, while maintaining the high adhesive strength of the monofunctional urethane acrylate, it was similar to the bifunctional urethane acrylate. It was confirmed that the gel fraction. Thereby, it has high adhesive force and cohesion force, and can have the outstanding durability in heat resistant and moisture-resistant heat conditions.

Claims (9)

Monofunctional urethane acrylate oligomers having at least one hydroxy group (-OH) at the terminal; Acrylate monomers; And a pressure-sensitive adhesive composition for optics containing a free radical initiator.
The optical pressure-sensitive adhesive composition of claim 1, wherein the monofunctional urethane acrylate oligomer has one or two hydroxy groups (-OH) at its ends.
The optical pressure-sensitive adhesive composition of claim 1, wherein the monofunctional urethane acrylate oligomer comprises an ester main chain, an ether main chain, or a main chain of a mixed structure thereof.
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 50,000.
The optical pressure-sensitive adhesive composition of claim 1, wherein the acrylate monomer is 1 to 4 functional.
The method according to claim 1, 25 to 80% by weight of a monofunctional urethane acrylate oligomer having at least one hydroxyl group (-OH) at the terminal; 15 to 70% by weight of acrylate monomers; And 0.1 to 5% by weight of a free radical initiator.
The adhesive which hardened the adhesive composition of any one of Claims 1-6.
Transparent substrate film;
Adhesive film comprising the pressure-sensitive adhesive of claim 7 formed on one surface of the transparent base film.
The pressure-sensitive adhesive film of claim 8, wherein the pressure-sensitive adhesive has a thickness of 25 to 1000 μm.