KR101988075B1 - Adhesive sheet for optical use - Google Patents

Adhesive sheet for optical use Download PDF

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Publication number
KR101988075B1
KR101988075B1 KR1020150088521A KR20150088521A KR101988075B1 KR 101988075 B1 KR101988075 B1 KR 101988075B1 KR 1020150088521 A KR1020150088521 A KR 1020150088521A KR 20150088521 A KR20150088521 A KR 20150088521A KR 101988075 B1 KR101988075 B1 KR 101988075B1
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South Korea
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sensitive adhesive
pressure
meth
adhesive layer
surface roughness
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KR1020150088521A
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Korean (ko)
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KR20170000035A (en
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장애정
김장순
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주식회사 엘지화학
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
    • C09J4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/385—Acrylic polymers

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Adhesive Tapes (AREA)
  • Chemical Kinetics & Catalysis (AREA)

Abstract

The present invention relates to an optical pressure-sensitive adhesive sheet, and more particularly, to an optical pressure-sensitive adhesive sheet which relieves an increase in surface roughness of a pressure-sensitive adhesive layer according to a release paper having a relatively large surface roughness.

Description

ADHESIVE SHEET FOR OPTICAL USE

The present invention relates to an optical pressure-sensitive adhesive sheet, and more particularly, to an optical pressure-sensitive adhesive sheet which relieves an increase in surface roughness of a pressure-sensitive adhesive layer according to a release paper having a relatively large surface roughness.

Electronic devices such as PDAs, mobile communication terminals, and navigation systems for vehicles are forming a large market. The technical goals pursued in such electronic devices are thinning, weight reduction, low power consumption, high resolution, and high brightness. In such an electronic device, a touch screen panel capable of operating a screen by touching with a finger or the like is applied, and a transparent conductive plastic film or the like is used to fill a gap between the panel and the LCD.

For example, there is a film formed of a polyethylene terephthalate (PET) film as a base material and a conductive layer such as indium tin oxide (ITO) formed on one surface thereof. The film may be a pressure- Conductive glass, a reinforcing material or a decoupled film by a sheet. The optical pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet is required to have various physical properties such as optical properties and durability.

In recent years, an attempt has been made to thin the optical adhesive sheet in order to achieve the aforementioned technical goals. Particularly, attempts have been repeated to reduce the thickness of the pressure-sensitive adhesive layer interposed between the pressure-sensitive adhesive sheets. When the thickness of the pressure-sensitive adhesive layer is interposed at a certain level or less, physical properties such as adhesion properties and durability .

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an optical adhesive sheet for optical applications which can alleviate an increase in surface roughness of a pressure-sensitive adhesive layer according to a release paper having a relatively large surface roughness.

Another object of the present invention is to provide an optical adhesive sheet having improved physical properties such as adhesiveness, durability and the like by alleviating an increase in surface roughness of the pressure-sensitive adhesive layer by the release paper.

According to an aspect of the present invention, an adhesive layer is interposed between a release paper having a surface roughness (R 1 ) of 400 nm or more and a plastic film, and the upper surface roughness (R 2 ) of the pressure- A difference in lower surface roughness (R 3 ) of the pressure-sensitive adhesive layer in contact with the pressure-sensitive adhesive sheet for optical use of 500 nm or more can be provided.

Here, the difference between the upper surface roughness (R 2 ) of the pressure-sensitive adhesive layer and the lower surface roughness (R 4 ) of the plastic film in contact with the pressure-sensitive adhesive layer may be less than 50 nm.

Here, the difference between the lower surface roughness (R 3 ) of the pressure-sensitive adhesive layer and the surface roughness (R 1 ) of the release paper in contact with the pressure-sensitive adhesive layer may be 400 nm or more.

Here, the thickness of the pressure-sensitive adhesive layer may be 50 μm or more and less than 150 μm.

Here, the upper surface roughness (R 2 ) of the pressure-sensitive adhesive layer may be 100 nm or less.

Here, the difference between the upper surface roughness (R 2 ) of the pressure-sensitive adhesive layer and the surface roughness (R 1 ) of the release paper in contact with the pressure-sensitive adhesive layer may be 500 nm or more.

Here, the pressure-sensitive adhesive layer may be formed by curing a resin composition which is a polymeric compound of a crosslinkable monomer containing a (meth) acrylic acid ester monomer and a carboxyl group.

Here, the resin composition may be a polymer of 80 to 95 parts by weight of a (meth) acrylic acid ester monomer and 5 to 20 parts by weight of a crosslinkable monomer containing a carboxyl group.

The (meth) acrylic ester monomer may be at least one selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) (meth) acrylate, 2-ethylhexyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (Meth) acrylate, isooctyl (meth) acrylate, isobonyl (meth) acrylate, isononyl (meth) acrylate, and any combination thereof.

Here, the crosslinking monomer containing a carboxyl group may be selected from the group consisting of acrylic acid, methacrylic acid, 2- (meth) acryloyloxyacetic acid, 3- (meth) acryloyloxypropyl acid, 4- (meth) Maleic acid, maleic acid, maleic acid, maleic acid, maleic acid, maleic acid, and combinations thereof.

Here, the resin composition may further include a first curing agent having a weight average molecular weight of 3,000 to 7,000,000 and a second curing agent having a weight average molecular weight of 200 to 300.

Here, the weight ratio of the first curing agent to the second curing agent may be 1: 2 to 2: 1.

The first curing agent may be selected from the group consisting of polyethylene glycol diacrylate, polypropylene glycol diacrylate, tetraethylene glycol diacrylate, and any combination thereof. ≪ / RTI >

Here, the second curing agent may be 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate (1,3-butylene glycol dimethacrylate 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol dimethacrylate, But are not limited to, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol divinyl ether, And any combination thereof.

Here, the plastic film may be a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, Urethane film, and ethylene-vinyl acetate copolymer film.

The optical pressure-sensitive adhesive sheet according to an embodiment of the present invention alleviates an increase in surface roughness of a pressure-sensitive adhesive layer according to a release paper having a relatively large surface roughness, thereby improving physical properties such as adhesion property and durability.

1 schematically shows an optical adhesive sheet according to an embodiment of the present invention.

Certain terms are hereby defined for convenience in order to facilitate a better understanding of the present invention. Unless otherwise defined herein, scientific and technical terms used in the present invention shall have the meanings commonly understood by one of ordinary skill in the art. Also, unless the context clearly indicates otherwise, the singular form of the term also includes plural forms thereof, and plural forms of the term should be understood as including its singular form.

Hereinafter, the optical adhesive sheet according to one embodiment of the present invention will be described in more detail.

According to one aspect of the present invention, an optical adhesive sheet having a pressure-sensitive adhesive layer 200 interposed between a release paper 100 and a plastic film 300 may be provided.

Here, the release paper 100 may be suitably selected and used according to the application, for example, a plastic film 300 such as polyethylene, polypropylene, polyethylene terephthalate and polyester film, paper, cloth or nonwoven fabric, , Paper having a surface roughness (R 1 ) of 400 nm or more can be suitably used.

As used herein, the term surface roughness refers to the degree of irregular irregularities having a short period occurring on the surface of the substrate or layer and having a relatively small amplitude, and may also be referred to as surface roughness. In addition, the term surface roughness as used herein can be understood as an arithmetic average roughness (JIS B 0601 (1994)).

Here, the plastic film 300 may be a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, A film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

The type and thickness of the release paper 100 and the plastic film 300 can be appropriately selected depending on the application in which the optical adhesive sheet is used and the required properties.

The pressure-sensitive adhesive layer 200 interposed between the release paper 100 and the plastic film 300 may be formed by curing a resin composition which is a polymer of a crosslinkable monomer containing a (meth) acrylic acid ester monomer and a carboxyl group.

At this time, the thickness of the pressure-sensitive adhesive layer 200 formed by curing the resin composition is preferably less than 150 m. The influence of the surface roughness of the release paper 100 on the pressure-sensitive adhesive layer 200 decreases as the thickness of the pressure-sensitive adhesive layer 200 increases. Generally, the thickness of the pressure-sensitive adhesive layer 200 in the optical pressure- The upper surface roughness of the pressure sensitive adhesive layer 200 is less than the lower surface of the plastic film 300 contacting the upper portion of the pressure sensitive adhesive layer 200 than the release paper 100 contacting the lower portion of the pressure sensitive adhesive layer 200, And the surface roughness of the surface. Therefore, when the thickness of the pressure-sensitive adhesive layer 200 is about 200 μm, the upper surface roughness of the pressure-sensitive adhesive layer 200 is maintained at a low level unless the surface roughness of the lower surface of the plastic film 300 is excessively large Is possible.

However, it is necessary to further reduce the thickness of the pressure-sensitive adhesive sheet, that is, the thickness of the pressure-sensitive adhesive layer 200, in accordance with the trend toward thinness of various electronic appliances to which the optical pressure-sensitive adhesive sheet is applied. The upper surface roughness of the pressure sensitive adhesive layer 200 is lower than the upper surface of the release paper 100 contacting the lower portion of the pressure sensitive adhesive layer 200 than the plastic film 300 contacting the upper portion of the pressure sensitive adhesive layer 200. [ Surface roughness.

Therefore, in such a case, the upper surface roughness of the pressure-sensitive adhesive layer 200 is generally formed at a level similar to or higher than the surface roughness of the release paper 100. This causes deterioration of the physical properties of the pressure-sensitive adhesive sheet such as adhesive property, durability and the like.

Therefore, the present invention is directed to an optical pressure-sensitive adhesive sheet which can maintain the upper surface roughness of the pressure-sensitive adhesive layer 200 at a low level even when the thickness of the pressure-sensitive adhesive layer 200 is less than 150 μm.

The (meth) acrylate monomer may be selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, (Meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, (Meth) acrylate, isooctyl (meth) acrylate, isobonyl (meth) acrylate, isononyl (meth) acrylate, and any combination thereof.

The crosslinkable monomer containing a carboxyl group may be selected from the group consisting of acrylic acid, methacrylic acid, 2- (meth) acryloyloxyacetic acid, 3- (meth) acryloyloxypropyl acid, 4- (meth) acryloyloxybutyric acid, Acrylic acid dimer, itaconic acid, maleic acid, and any combination thereof. The crosslinkable monomer has high reactivity and is excellent in cohesive force when copolymerized with other monomers, so that the cross-linking density of the pressure-sensitive adhesive layer 200 formed by curing can be increased.

Here, the resin composition may be a polymer of 80 to 95 parts by weight of a (meth) acrylic acid ester monomer and 5 to 20 parts by weight of a crosslinkable monomer containing a carboxyl group. Unlike the homopolymer formed by polymerization of the (meth) acrylic acid ester monomer alone, the resin composition forms a copolymer by the crosslinkable monomer containing a (meth) acrylic acid ester monomer and a carboxyl group, so that the pressure sensitive adhesive layer 200 has appropriate flexibility The crosslinking density can be controlled so that the crosslinking density is maintained.

If the amount of the (meth) acrylic ester monomer exceeds 95 parts by weight, the homopolymerization of the (meth) acrylic acid ester-based monomer increases, thereby further increasing the crosslinking density. In this case, the pressure-sensitive adhesive layer 200 formed by curing the resin composition has a low flexibility and is greatly affected by the release paper 100 having a relatively large surface roughness. As a result, the surface roughness of the pressure-sensitive adhesive layer 200 increases, which drastically reduces the physical properties such as adhesion property, durability and the like.

Similarly, when the amount of the crosslinkable monomer containing the carboxyl group is more than 20 parts by weight, the cohesive force and the like are improved when copolymerized with the (meth) acrylate monomer, so that the crosslinking density is further increased. The pressure-sensitive adhesive layer 200 is greatly affected by the release paper 100 having low flexibility and relatively large surface roughness. As a result, the surface roughness of the pressure-sensitive adhesive layer 200 increases, which drastically reduces the physical properties such as adhesion property, durability and the like.

On the other hand, when the content of the (meth) acrylic acid ester-based monomer and the crosslinkable monomer containing a crosslinkable monomer and / or carboxyl group is excessively low, it is difficult to achieve the crosslinking density for ensuring adequate weatherability.

In another modified example, in order to ensure the flexibility and viscoelasticity of the resin composition during copolymerization, the resin composition may further include a crosslinkable monomer containing a hydroxyl group. The cross-linkable monomer containing a hydroxyl group can effectively lower the cross-link density by widening the interval between the monomers during copolymerization.

Examples of the crosslinkable monomer containing a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) (Meth) acrylate, 2-hydroxypropyleneglycol (meth) acrylate, 2-hydroxypropyleneglycol (meth) acrylate, 2-hydroxypropyleneglycol And the like can be used.

The resin composition may further include a first curing agent having a weight average molecular weight of 3,000 to 7,000,000 and a second curing agent having a weight average molecular weight of 200 to 300. [ The first curing agent and the second curing agent may be included in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the resin composition.

Here, the weight ratio of the first curing agent to the second curing agent may be 1: 2 to 2: 1. The weight ratio between the first curing agent and the second curing agent may vary depending on the surface roughness of the release paper 100 contacting the pressure-sensitive adhesive layer 200 and the surface of the plastic film 300, Can be adjusted accordingly.

The flexibility or elasticity of the cured PSA layer 200 may vary depending on the weight ratio of the first curing agent and the second curing agent and the flexibility and elasticity of the PSA layer 200 may be increased as the weight ratio of the first curing agent to the second curing agent increases. The elasticity increases. On the contrary, as the weight ratio of the second curing agent to the first curing agent increases, the flexibility and elasticity of the pressure-sensitive adhesive layer 200 decrease.

That is, the lower the surface roughness of the pressure-sensitive adhesive layer 200 as the thickness of the pressure-sensitive adhesive layer 200 becomes, the lower the surface roughness of the pressure-sensitive adhesive layer 200, Along the surface roughness of the upper surface of the substrate 100.

Therefore, it is necessary to increase the flexibility and elasticity of the pressure-sensitive adhesive layer 200 as the thickness of the pressure-sensitive adhesive layer 200 becomes thinner. Therefore, it is preferable to increase the weight ratio of the first curing agent to the second curing agent as the thickness of the pressure-sensitive adhesive layer 200 becomes thinner.

The first curing agent may be selected from the group consisting of polyethylene glycol diacrylate, polypropylene glycol diacrylate, tetraethylene glycol diacrylate, and any combination thereof. ≪ / RTI >

Here, the second curing agent may be 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate (1,3-butylene glycol dimethacrylate 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol dimethacrylate, But are not limited to, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol divinyl ether, And any combination thereof.

Further, the resin composition may use a photoinitiator that initiates photo-curing reaction with light of about 295 nm to about 420 nm. As the photoinitiator, for example, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (TPO) -based compounds or acylphosphine-based compounds Compounds.

The optical adhesive sheet according to an embodiment of the present invention has been described with reference to the composition of the pressure-sensitive adhesive layer 200 interposed between the release paper 100 and the plastic film 300. In the following, The optical adhesive sheet according to one embodiment of the present invention will be described focusing on the surface roughness of the optical sheet 200.

According to one aspect of the present invention, a pressure-sensitive adhesive layer 200 is interposed between a release paper 100 having a surface roughness R 1 of 400 nm or more and a plastic film 300, The difference between the upper surface roughness R 2 of the adhesive layer 200 and the lower surface roughness R 3 of the pressure-sensitive adhesive layer 200 in contact with the release paper 100 is 500 nm or more.

Generally, when the thickness of the pressure-sensitive adhesive layer 200 is about 200 μm when the pressure-sensitive adhesive layer 200 is formed by curing the resin composition on the release paper 100 having a surface roughness R 1 of 400 nm or more, The upper surface roughness R 2 of the pressure-sensitive adhesive layer 200 is less than the roughness of the lower surface of the plastic film 300 contacting the upper portion of the pressure-sensitive adhesive layer 200 than the release paper 100 contacting the lower portion of the pressure- R 4 ).

That is, the upper surface roughness R 2 of the pressure-sensitive adhesive layer 200 and the roughness R 4 of the lower surface of the plastic film 300 have similar values.

On the other hand, when the thickness of the pressure-sensitive adhesive layer 200 is less than 150 μm when the pressure-sensitive adhesive layer 200 is formed on the release paper 100 having a surface roughness R 1 of 400 nm or more, The upper surface roughness R 2 of the adhesive layer 200 is greater than the roughness R 1 of the upper surface of the release paper 100 contacting the lower portion of the pressure sensitive adhesive layer 200 than the plastic film 300 contacting the upper portion of the pressure sensitive adhesive layer 200. ). ≪ / RTI >

That is, the upper surface roughness R 2 of the pressure-sensitive adhesive layer 200 and the roughness R 1 of the upper surface of the release paper 100 have similar values.

The adhesive sheet for optical use according to an embodiment of the present invention may be used when an adhesive layer 200 having a thickness of less than 150 μm is formed by curing the resin composition on a release paper 100 having a surface roughness R 1 of 400 nm or more The difference between the upper surface roughness R 2 of the pressure sensitive adhesive layer 200 contacting the plastic film 300 and the lower surface roughness R 3 of the pressure sensitive adhesive layer 200 contacting the release paper 100 is 500 nm Or more.

Accordingly, the surface roughness R 1 of the release paper 100 hardly affects the upper surface roughness R 2 of the pressure-sensitive adhesive layer 200, and the surface roughness R 1 of the release paper 100 is hardly affected by the release surface 100 having a relatively large surface roughness By modifying the increase in the surface roughness of the pressure-sensitive adhesive layer (200), physical properties such as adhesion property, durability and the like can be improved.

In the present invention, the surface roughness of each layer may vary depending on not only the layer thickness and composition but also the conditions of the manufacturing process, but it is important that each layer has a difference in surface roughness or surface roughness within the above-mentioned numerical range.

The difference between the upper surface roughness R 2 of the pressure sensitive adhesive layer 200 and the lower surface roughness R 4 of the plastic film 300 in contact with the pressure sensitive adhesive layer 200 is less than 50 nm, May be less than 20 nm.

That is, the upper surface roughness R 2 of the pressure-sensitive adhesive layer 200 has a value similar to the lower surface roughness R 4 of the plastic film 300 in contact with the pressure-sensitive adhesive layer 200.

Generally, the upper surface roughness R 2 of the pressure-sensitive adhesive layer 200 may also be formed at a level of about 100 nm or less, considering that the surface roughness of the plastic film 300 is about 100 nm or less.

Even though the pressure-sensitive adhesive layer 200 is formed on the release paper 100 having a relatively large surface roughness due to the curing of the resin composition having the above-described composition, the pressure-sensitive adhesive layer 200 may be formed by the flexibility and elasticity of the pressure- (R 1 ) of the upper surface of the release paper 100 in contact with the lower portion of the release paper 100.

The difference between the lower surface roughness R 3 of the pressure-sensitive adhesive layer 200 and the surface roughness R 1 of the release paper 100 in contact with the pressure-sensitive adhesive layer 200 is 400 nm or more.

In addition, the difference between the upper surface roughness R 2 of the pressure-sensitive adhesive layer 200 and the surface roughness R 1 of the release paper 100 contacting the pressure-sensitive adhesive layer 200 may be 300 nm or more.

That is, the influence of the upper surface roughness R 2 of the pressure-sensitive adhesive layer 200 on the surface roughness R 1 of the release paper 100 in contact with the pressure-sensitive adhesive layer 200 is minimized, The surface can be planarized as much as possible, thereby ensuring excellent adhesive properties.

Hereinafter, specific embodiments of the present invention will be described. However, the embodiments described below are only intended to illustrate or explain the present invention, and thus the present invention should not be limited thereto.

Example  And Comparative Example

Example  One

An acrylic resin was prepared by copolymerizing 2-ethylhexyl (meth) acrylate (800 g), methyl (meth) acrylate (140 g) and acrylic acid (60 g) using a bulk heat polymerization process. The weight average molecular weight of the acrylic resin was about 700,000 g / mol.

Then, based on 100 parts by weight of the acrylic resin, 0.5 part by weight of a photoinitiator (Irgacure 651), 0.5 part by weight of a curing agent (tetraethylene glycol diacrylate) and 10 parts by weight of an adhesion promoter (Foral 85) were mixed to prepare a resin composition.

A resin composition was formed to a thickness of 50 탆 on a release paper having a surface roughness (R 1 ) of 525 nm, a PET film having a surface roughness (R 4 ) of 83 nm was laminated thereon, Was cured to prepare an optical pressure-sensitive adhesive sheet.

Example  2

A pressure-sensitive adhesive layer was formed using the same resin composition as in Example 1, except that the pressure-sensitive adhesive layer had a thickness of 100 μm on a release paper having a surface roughness (R 1 ) of 525 nm.

Example  3

Except that 0.5 part by weight of 1,6-hexanediol dimethacrylate was used as a curing agent and a thickness of 125 μm was formed on a release paper having a surface roughness (R 1 ) of 525 nm, Sheet.

Comparative Example  One

Sensitive adhesive sheet for optical use was prepared in the same manner as in Example 1, except that 0.5 part by weight of 1,6-hexanediol dimethacrylate was used as a curing agent.

Comparative Example  2

Except that 0.5 part by weight of 1,6-hexanediol divinyl ether was used as a curing agent and a pressure-sensitive adhesive layer was formed to a thickness of 100 mu m on a release paper having a surface roughness (R 1 ) of 525 nm. Sensitive adhesive sheet was prepared.

The results of measuring the surface roughness of the pressure-sensitive adhesive layer at each interface of the optical pressure-sensitive adhesive sheet produced according to Examples and Comparative Examples are shown in Table 1 below. The surface roughness was measured according to JIS B 0601.

Illuminance Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 R 2 97 nm 81 nm 73 nm 442 nm 364 nm R 3 737 nm 715 nm 598 nm 787 nm 726 nm

* R 2 : upper surface roughness of the pressure-sensitive adhesive layer in contact with the PET film; R 3 : Lower surface roughness of the pressure-sensitive adhesive layer in contact with release paper.

Experimental Method

Durability measurement

Each of the pressure-sensitive adhesive sheets for optical sheets was prepared and stored for 3 days under the conditions of 85 ° C and 85% relative humidity, and visually observed for bubbles (no bubbles = pass; bubbles = fail).

Thermal shock  inspection

Each of the pressure-sensitive adhesive sheets for optical sheets was produced in accordance with Examples and Comparative Examples, and 30 cycles were performed for 1 hour at -40 ° C for 1 hour at 80 ° C for 30 cycles, Do not pass = bubble = fail.

Adhesive strength measurement

The pressure-sensitive adhesive sheet prepared according to Examples and Comparative Examples was cut to a size of 25 mm * 40 mm (width * length), then the release paper was removed, and the paper was attached to the glass substrate one time with 2 kg rollers. Was peeled off in a direction of 180 DEG at a rate of 300 mm / min to measure the adhesive force.

division durability Thermal shock test Adhesion (g / in) Example 1 pass pass 1740 Example 2 pass pass 1623 Example 3 pass pass 1689 Comparative Example 1 fail fail 1242 Comparative Example 2 fail fail 1317

As a result of the test results shown in Table 2, it was confirmed that reliability of the optical adhesive sheets prepared according to Examples 1 to 3 was improved due to no durability and no bubbles as a result of the thermal shock test.

In addition, it was confirmed that even when the pressure-sensitive adhesive layer is formed thin on the release paper having a large surface roughness, the increase in the surface roughness of the pressure-sensitive adhesive layer is alleviated and the pressure-sensitive adhesive property is improved.

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 of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

Claims (14)

A pressure-sensitive adhesive layer is interposed between a release film having a surface roughness (R 1 ) of 400 nm or more and a plastic film,
Wherein the difference between the upper surface roughness (R 2 ) of the pressure-sensitive adhesive layer in contact with the plastic film and the lower surface roughness (R 3 ) of the pressure-sensitive adhesive layer in contact with the release paper is 500 nm or more.
The method according to claim 1,
Wherein the difference between the upper surface roughness (R 2 ) of the pressure-sensitive adhesive layer and the lower surface roughness (R 4 ) of the plastic film in contact with the pressure-sensitive adhesive layer is less than 50 nm.
The method according to claim 1,
Wherein the thickness of the pressure-sensitive adhesive layer is 50 占 퐉 or more and less than 150 占 퐉.
The method according to claim 1,
Wherein the pressure-sensitive adhesive layer has an upper surface roughness (R 2 ) of 100 nm or less.
The method according to claim 1,
Wherein the difference between the upper surface roughness (R 2 ) of the pressure-sensitive adhesive layer and the surface roughness (R 1 ) of the release paper in contact with the pressure-sensitive adhesive layer is 300 nm or more.
The method according to claim 1,
Wherein the pressure-sensitive adhesive layer is formed by curing a resin composition which is a polymeric compound of a crosslinkable monomer containing a (meth) acrylic acid ester monomer and a carboxyl group.
The method according to claim 6,
Wherein the resin composition is a polymer of 80 to 95 parts by weight of a (meth) acrylic acid ester monomer and 5 to 20 parts by weight of a crosslinkable monomer containing a carboxyl group.
The method according to claim 6,
The (meth) acrylic acid ester monomer may be selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, Ethyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, Isocyanate (meth) acrylate, isooctyl (meth) acrylate, isobonyl (meth) acrylate, isononyl (meth) acrylate and any combination thereof.
The method according to claim 6,
The crosslinkable monomer containing a carboxyl group may be selected from the group consisting of acrylic acid, methacrylic acid, 2- (meth) acryloyloxyacetic acid, 3- (meth) acryloyloxypropyl acid, 4- (meth) acryloyloxybutyric acid, Acrylic acid dimer, itaconic acid, maleic acid, and any combination thereof.
The method according to claim 6,
Wherein the resin composition further comprises a first curing agent having a weight average molecular weight of 3,000 to 7,000,000 and a second curing agent having a weight average molecular weight of 200 to 300. [
11. The method of claim 10,
Wherein the weight ratio of the first curing agent to the second curing agent is 1: 2 to 2: 1.
11. The method of claim 10,
Wherein the first curing agent is selected from the group consisting of polyethylene glycol diacrylate, polypropylene glycol diacrylate, tetraethylene glycol diacrylate, and any combination thereof. Wherein the pressure-sensitive adhesive sheet is an adhesive sheet for optical use.
11. The method of claim 10,
The second curing agent may be 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol divinyl ether, and the like. Wherein the pressure-sensitive adhesive sheet is an optical adhesive sheet.
The method according to claim 1,
The plastic film may be at least one selected from the group consisting of a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, And an ethylene-vinyl acetate copolymer film.
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