WO2023095657A1

WO2023095657A1 - Covered optical adhesive sheet

Info

Publication number: WO2023095657A1
Application number: PCT/JP2022/042207
Authority: WO
Inventors: 和広山村; 新藤原
Original assignee: 日東電工株式会社
Priority date: 2021-11-26
Filing date: 2022-11-14
Publication date: 2023-06-01
Also published as: TW202330834A

Abstract

An optical adhesive sheet (X), as a covered optical adhesive sheet according to the present invention, comprises an optical adhesive sheet (10), a transparent separation liner (20), and a surface protection film (30), in this order in the thickness direction (H). The optical adhesive sheet (10) has a first surface (11) and a second surface (12) on the reverse side from the first surface (11). The transparent separation liner (20) is disposed on the first surface (11). The surface protection film (30) has an adhesive surface (30a) and is affixed to the transparent separation liner (20) via the adhesive surface (30a). A first peeling force between the surface protection film (30) and the transparent separation liner (20) under the conditions of a peeling angle of 180° and a pulling speed of 300 mm/minute is smaller than a second peeling force between the transparent separation liner (20) and the optical adhesive sheet (10) under said conditions.

Description

Covered optical adhesive sheet

The present invention relates to a covered optical pressure-sensitive adhesive sheet.

A light-transmitting pressure-sensitive adhesive sheet (optical pressure-sensitive adhesive sheet) is used to manufacture optical articles such as display panels. A display panel has a laminated structure including a pixel panel, a cover member, and the like. In the display panel manufacturing process, the optical adhesive sheet is used for bonding between elements included in a laminate structure, for example, on the light exit side (image display side) of the pixel panel. Thus, the optical pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet that is placed at a portion of the optical article through which light passes. Further, the optical adhesive sheet is conventionally manufactured in the form of a release liner-attached optical adhesive sheet in which one or both sides of the same sheet are coated with a release liner. Techniques related to such an optical adhesive sheet are described, for example, in Patent Document 1 below.

JP 2012-62345 A

In the manufacturing process of the optical adhesive sheet, the presence or absence of foreign matter inside and on the surface of the optical adhesive sheet is inspected by irradiating the optical adhesive sheet with a release liner with light of a predetermined wavelength. Further, in the manufacturing process of optical articles, after an optical pressure-sensitive adhesive sheet coated with a release liner on one side is attached to a component of an optical article, the optical pressure-sensitive adhesive sheet with a release liner is irradiated with light of a predetermined wavelength. inspects the presence or absence of foreign matter inside and on the surface of the same sheet (foreign matter inspection of optical adhesive sheet in optical article manufacturing process).

On the other hand, in the technical field of optoelectronics, various optical products are becoming more sophisticated. For example, in the technical field of image display, the number of pixels in display panels is increasing. As optical articles become more sophisticated, a higher degree of cleanness is required for the light-passing portion of the optical article. An optical pressure-sensitive adhesive sheet is required to be supplied to an optical article manufacturing process with a high degree of cleanliness. As the degree of cleanness required is higher, detection of minute foreign matter is required in foreign matter inspection (that is, more precise inspection is required).

However, in a conventional optical pressure-sensitive adhesive sheet with a release liner, after the optical pressure-sensitive adhesive sheet is manufactured, until the optical pressure-sensitive adhesive sheet is supplied to the manufacturing process of an optical article (for example, the process of transporting and conveying the same sheet), Environmental contaminants may adhere to the exposed surface of the release liner, and scratches may occur. In such a case, it becomes difficult to perform a precise inspection in the foreign matter inspection of the optical adhesive sheet in the optical article manufacturing process. This is because it is impossible to distinguish between the above-mentioned subsequent environmental contaminants and scratches on the release liner and contaminants on the optical pressure-sensitive adhesive sheet itself. Such a conventional optical pressure-sensitive adhesive sheet with a release liner is not suitable for supplying an optical pressure-sensitive adhesive sheet with a high degree of cleanliness to the manufacturing process of optical articles.

The present invention provides a covered optical pressure-sensitive adhesive sheet suitable for supplying an optical pressure-sensitive adhesive sheet with a high degree of cleanliness to the manufacturing process of optical articles.

The present invention [1] comprises an optical adhesive sheet, a transparent release liner, and a surface protective film in this order in the thickness direction, and the optical adhesive sheet has a first surface and a second surface opposite to the first surface. The transparent release liner is disposed on the first surface, and the surface protection film has an adhesive surface and adheres to the transparent release liner at the adhesive surface. , the first peel force between the surface protective film and the transparent release liner under the conditions of a peel angle of 180° and a tensile speed of 300 mm/min is a covered optical adhesive sheet having a second peel force of less than .

The covered optical adhesive sheet, as described above, comprises an optical adhesive sheet, a transparent release liner on the first surface of the sheet, and a surface protective film on the liner. Such a configuration prevents adhesion of environmental foreign matter to the transparent release liner on the first surface side of the optical pressure-sensitive adhesive sheet until the covered optical pressure-sensitive adhesive sheet is supplied to the optical article manufacturing process after the covered optical pressure-sensitive adhesive sheet is manufactured. It is suitable for preventing the release liner from being damaged by the surface protection film. Also, in the covered optical pressure-sensitive adhesive sheet, as described above, the first peel force between the surface protection film and the transparent release liner is smaller than the second peel force between the transparent release liner and the optical pressure-sensitive adhesive sheet. In such a configuration, after the optical pressure-sensitive adhesive sheet side of the covered optical pressure-sensitive adhesive sheet is adhered to the components of the optical article, the transparent release liner is kept adhered to the optical pressure-sensitive adhesive sheet on the optical article. Suitable for appropriately peeling the surface protective film from the transparent release liner (peeling step). After peeling the surface protective film, the optical pressure-sensitive adhesive sheet with the transparent release liner can be properly inspected. Therefore, the covered optical pressure-sensitive adhesive sheet of the present invention is suitable for supplying an optical pressure-sensitive adhesive sheet with a high degree of cleanliness to the manufacturing process of optical articles.

In the present invention [2], after the surface protection film has been laminated to the cycloolefin polymer film, 1.0 N is applied to the cycloolefin polymer film under the conditions of a peeling angle of 180° and a tensile speed of 300 mm/min. / The covered optical pressure-sensitive adhesive sheet according to [1] above, which has a peel strength of 50 mm or less.

In such a configuration, after the optical pressure-sensitive adhesive sheet side of the covered optical pressure-sensitive adhesive sheet is adhered to the optical article, the transparent release liner is kept attached to the optical pressure-sensitive adhesive sheet on the optical article. It is preferable for properly peeling the surface protective film from the liner.

In the present invention [3], after the surface protection film is laminated to the cycloolefin polymer film, the cycloolefin polymer film is subjected to a third peeling force under the conditions of a peeling angle of 180° and a tensile speed of 300 mm/min. After two weeks at 50° C. from the bonding of the surface protective film to the cycloolefin polymer film, the fourth peel is applied to the cycloolefin polymer film under the conditions of a peeling angle of 180° and a tensile speed of 300 mm/min. The covered optical pressure-sensitive adhesive sheet according to [1] or [2] above, wherein the ratio of the fourth peel force to the third peel force is 0.8 or more and 1.5 or less.

Such a configuration is preferable from the viewpoint of stabilizing the peeling force required for peeling the surface protective film in the peeling process.

The present invention [4] is the above [1] to [3], wherein the surface protection film has an adhesive layer forming the adhesive surface, and the adhesive layer has a gel fraction of 80% or more. The covered optical pressure-sensitive adhesive sheet according to any one is included.

Such a configuration is preferable for realizing a peeling force (slight adhesiveness) of about 1.0 N/50 mm or less for the adhesive surface of the surface protection film.

The present invention [5] is the covered optical pressure-sensitive adhesive sheet according to any one of [1] to [4] above, wherein the surface of the transparent release liner on the surface protection film side has a surface roughness Ra of 20 nm or less. including.

Such a configuration is preferable from the viewpoint of achieving both the slight adhesion of the surface protective film to the transparent release liner and the suppression of adhesive residue on the surface of the transparent release liner after the surface protective film is peeled off.

The present invention [6] further comprises an additional transparent release liner and an additional surface protection film on the second surface side of the optical adhesive sheet, wherein the additional transparent release liner is attached to the optical adhesive sheet. Arranged on the second surface, the additional surface protection film has an adhesive surface and is attached to the additional transparent release liner with the adhesive surface of [1] to [5] above. The covered optical pressure-sensitive adhesive sheet according to any one is included.

Such a covered optical pressure-sensitive adhesive sheet is subject to adhesion of environmental foreign matter to the transparent release liner on the second surface side of the optical pressure-sensitive adhesive sheet until it is supplied to the optical article manufacturing process after the sheet is manufactured, and Suitable for protecting the transparent release liner from damage by the surface protection film.

The present invention [7] is the covered optical adhesive according to [6] above, wherein the second peel force is smaller than the fifth peel force under the conditions between the additional transparent release liner and the optical adhesive sheet. Including sheet.

When using the covered optical pressure-sensitive adhesive sheet in the manufacturing process of an optical article, such a configuration can maintain the additional transparent release liner adhered to the second surface of the optical pressure-sensitive adhesive sheet, and the optical pressure-sensitive adhesive sheet. It is preferred for proper release of the clear release liner from the first surface.

The present invention [8] includes the covered optical pressure-sensitive adhesive sheet according to any one of [1] to [5] above, further comprising a polarizer film disposed on the second surface of the optical pressure-sensitive adhesive sheet. .

According to such a configuration, the polarizer with an adhesive layer, in which the adhesive layer is formed on the surface of the polarizer by the optical adhesive sheet, can be used as an optical article in a state where the optical adhesive sheet (adhesive layer) has a high degree of cleanliness. Can be fed into the manufacturing process.

1 is a cross-sectional view of one embodiment of a covered optical pressure-sensitive adhesive sheet of the present invention; FIG. FIG. 4 is a cross-sectional view of a modified example of the covered optical pressure-sensitive adhesive sheet of the present invention. In this modification, a polarizer film is arranged on the second surface of the optical adhesive sheet.

An optical adhesive sheet X as an embodiment of the covered optical adhesive sheet of the present invention comprises an optical adhesive sheet 10,

transparent release liners

20 and 40, and surface

protective films

30 and 50, as shown in FIG. Specifically, the optical adhesive sheet X includes a surface protection film 30, a transparent release liner 20, an optical adhesive sheet 10, a transparent release liner 40 (additional transparent release liner), and a surface protection film 50 (additional surface protective film) in order in the thickness direction H. The optical adhesive sheet X has a sheet shape that spreads in a direction perpendicular to the thickness direction H (plane direction). The optical adhesive sheet X has a first surface 11 (first adhesive surface) on one surface in the thickness direction H and a second surface 12 (second adhesive surface) on the other surface in the thickness direction H.

The optical adhesive sheet 10 is an optically transparent adhesive sheet. The optical pressure-sensitive adhesive sheet 10 is a transparent pressure-sensitive adhesive sheet that is placed at a light-passing portion of an optical article, and is used as a component of the optical article. Optical articles include, for example, display panels. A display panel has a laminated structure including a pixel panel, a cover member, and the like. In the manufacturing process of the display panel, predetermined elements arranged on the image display side of the pixel panel are bonded together via, for example, an optical adhesive sheet. Such display panels include ultra-high-definition display panels for VR (Virtual Reality) applications, AR (Augmented Reality) applications, and the like.

A transparent release liner 20 is placed on the first surface 11 of the optical adhesive sheet 10 . The transparent release liner 20 protects the first surface 11 side of the optical adhesive sheet 10 . The surface protective film 30 has an adhesive surface 30a and is adhered to the transparent release liner 20 with the adhesive surface 30a. The surface protective film 30 protects the transparent release liner 20 and the optical adhesive sheet 10 on the first surface 11 side of the optical adhesive sheet 10 .

In the optical adhesive sheet X, the first peel force between the surface protective film 30 and the transparent release liner 20 under the conditions of a peeling angle of 180° and a tensile speed of 300 mm/min (peeling of the surface protective film 30 from the transparent release liner 20 (the force required to release the transparent release liner 20 from the optical adhesive sheet 10) is smaller than the second release force (the force required to release the transparent release liner 20 from the optical adhesive sheet 10) between the transparent release liner 20 and the optical adhesive sheet 10 under the above conditions.

As long as the first peel force is smaller than the second peel force, it is preferably 0.01 N/50 mm or more, more preferably 0.02 N/50 mm or more, still more preferably 0.03 N/50 mm or more, and still more preferably 0.05 N. /50 mm or more, particularly preferably 0.1 N/50 mm or more, preferably 0.95 N/50 mm or less, more preferably 0.9 N/50 mm or less, still more preferably 0.8 N/50 mm or less, still more preferably 0.6 N/50 mm or less, particularly preferably 0.5 N/50 mm or less. This configuration regarding the first peel force is preferable for achieving both adhesion and retention of the surface protective film 30 to the transparent release liner 20 and good peelability of the surface protective film 30 from the transparent release liner 20 . The high adhesion retention of the surface protective film 30 to the transparent release liner 20 helps to prevent foreign matter from entering between the transparent release liner 20 and the surface protective film 30 .

The second peel force is preferably 0.02 N/50 mm or more, more preferably 0.03 N/50 mm or more, still more preferably 0.05 N/50 mm or more, still more preferably 0.1 N/50 mm or more, and particularly preferably 0. 15 N/50 mm or more, preferably 1.0 N/50 mm or less, more preferably 0.95 N/50 mm or less, still more preferably 0.9 N/50 mm or less, still more preferably 0.8 N/50 mm or less, and particularly preferably is 0.7N/50mm or less. This configuration regarding the second release force is preferable for achieving both adhesion and retention of the transparent release liner 20 to the optical adhesive sheet 10 and good releasability of the transparent release liner 20 from the optical adhesive sheet 10 . The high adherence retention of the transparent release liner 20 to the optical adhesive sheet 10 helps to prevent foreign matter from entering between the optical adhesive sheet 10 and the transparent release liner 20 .

A transparent release liner 40 is placed on the second surface 12 of the optical adhesive sheet 10 . A transparent release liner 40 protects the second surface 12 side of the optical adhesive sheet 10 . The surface protective film 50 has an adhesive surface 50a and is adhered to the transparent release liner 40 with the adhesive surface 50a. The surface protective film 50 protects the transparent release liner 40 and the optical adhesive sheet 10 on the second surface 12 side of the optical adhesive sheet 10 .

In the optical adhesive sheet X, the force required to peel the transparent release liner 20 from the optical adhesive sheet 10 (second peel force) and the force required to peel the transparent release liner 40 from the optical adhesive sheet 10 (second 5 peel force) may be the same or different. For example, the second peel force is less than the fifth peel force. In this case, the transparent release liner 20 is a light release liner with relatively low release force, and the transparent release liner 40 is a heavy release liner with relatively high release force.

The optical adhesive sheet X is used in the manufacturing process of optical articles. For example, after integrally peeling the transparent release liner 20 and the surface protection film 30 from the optical adhesive sheet 10 of the optical adhesive sheet X, the first surface 11 of the optical adhesive sheet 10 is adhered to a predetermined first member, and the optical adhesive sheet is After integrally peeling the transparent release liner 40 and the surface protection film 50 from the optical adhesive sheet 10, the second surface 12 of the optical adhesive sheet 10 is adhered to a predetermined second member (the first member and the second member are optical articles, respectively). is one element in the laminated structure of In this way, the first member and the second member can be bonded via the optical adhesive sheet 10 .

The optical adhesive sheet X comprises the optical adhesive sheet 10, the transparent release liner 20 on the first surface 11 of the sheet, and the surface protective film 30 on the liner, as described above. Such a configuration prevents environmental foreign matter from adhering to the transparent release liner 20 on the first surface 11 side of the optical adhesive sheet 10 until it is supplied to the optical article manufacturing process after the optical adhesive sheet X is manufactured. Also, the surface protection film 30 is suitable for preventing the transparent release liner 20 from being damaged.

In the optical adhesive sheet X, as described above, the first peel force between the surface protective film 30 and the transparent release liner 20 is greater than the second peel force between the transparent release liner 20 and the optical adhesive sheet 10. small. Such a configuration is suitable for appropriately peeling the surface protective film 30 from the transparent release liner 20 while maintaining the state in which the transparent release liner 20 is adhered to the optical adhesive sheet 10 . After the surface protective film 30 is peeled off, the optical adhesive sheet 10 with the transparent release liner 20 can be properly inspected in detail in the inspection process.

Therefore, the optical adhesive sheet X is suitable for supplying an optical adhesive sheet with a high degree of cleanliness to the manufacturing process of optical articles.

After the surface protection film 30 is attached to the cycloolefin polymer (COP) film, the peel angle is 180° and the tensile speed is 300 mm/min. It has a third peel force of 50 mm or less. Specifically, the third peeling force is the force required to peel the surface protection film 30 from the COP film under the above conditions. The third peel force is more preferably 0.95 N/50 mm or less, still more preferably 0.9 N/50 mm or less, even more preferably 0.8 N/50 mm or less, still more preferably 0.6 N/50 mm or less, and particularly preferably It is 0.5N/50mm or less. Such a configuration is preferable for appropriately peeling the surface protective film 30 from the transparent release liner 20 while maintaining the state in which the transparent release liner 20 is adhered to the optical adhesive sheet 10 . The third peel force is preferably 0.02 N/50 mm or more, more preferably 0.03 N/50 mm or more, still more preferably 0.05 N/50 mm or more, still more preferably 0.1 N/50 mm or more, and particularly preferably 0.15N/50mm or more. Such a configuration is preferable for ensuring the adhered state of the surface protective film 30 to the transparent release liner 20 during the transportation process of the optical adhesive sheet X, for example.

The surface protective film 30 has a fourth peel force against the cycloolefin polymer film under the conditions of a peel angle of 180° and a tensile speed of 300 mm/min after two weeks have passed at 50° C. from bonding to the cycloolefin polymer film. and the ratio of the fourth peel force to the third peel force is preferably 0.8 or more, more preferably 0.9 or more, and preferably 1.5 or less, more preferably 1.3 or less (The fourth peeling force is the force required to peel the surface protective film 30 from the COP film under the above conditions after two weeks have passed at 50° C. from the bonding). Such a configuration is preferable from the viewpoint of stabilizing the peeling force required for peeling the surface protective film 30 . The fourth peel force is preferably 0.02 N/50 mm or more, more preferably 0.03 N/50 mm or more, still more preferably 0.05 N/50 mm or more, still more preferably 0.1 N/50 mm or more, and particularly preferably 0.15 N/50 mm or less, preferably 0.95 N/50 mm or less, more preferably 0.9 N/50 mm or less, even more preferably 0.8 N/50 mm or less, still more preferably 0.6 N/50 mm or less, Particularly preferably, it is 0.5 N/50 mm or less.

The surface protection film 30 preferably has an adhesive layer that forms the adhesive surface 30a, and the adhesive layer has a gel fraction of 80% or more. The gel fraction is more preferably 85% or higher, still more preferably 90% or higher. Such a configuration is preferable for realizing a peeling force (slight adhesiveness) of about 1.0 N/50 mm or less for the adhesive surface of the surface protective film. The gel fraction is, for example, 95% or less. The gel fraction can be measured by the method described below with respect to the examples.

The surface roughness Ra (arithmetic mean surface roughness according to JIS B 0601-2001) of the surface of the transparent release liner 20 on the surface protective film 30 side is preferably 20 nm or less, more preferably 17 nm or less, and even more preferably 15 nm or less. , particularly preferably 12 nm or less, more preferably 10 nm or less, even more preferably 8 nm or less, particularly preferably 6 nm or less, and extremely preferably 5 nm or less. Such a configuration is preferable from the viewpoint of achieving both the slight adhesion of the surface protective film 30 to the transparent release liner 20 and the suppression of adhesive residue on the surface of the transparent release liner 20 after the surface protective film 30 is peeled off. The surface roughness Ra is, for example, 0.1 nm or more.

The surface roughness Rz (maximum height according to JIS B 0601-2001) of the surface of the transparent release liner 20 on the side of the surface protective film 30 is preferably 600 nm or less, more preferably 400 nm or less, still more preferably 300 nm or less. It is preferably 200 nm or less, more preferably 100 nm or less, still more preferably 80 nm or less, particularly preferably 60 nm or less, and extremely preferably 50 nm or less. Such a configuration is preferable from the viewpoint of achieving both the slight adhesion of the surface protective film 30 to the transparent release liner 20 and the suppression of adhesive residue on the surface of the transparent release liner 20 after the surface protective film 30 is peeled off. The surface roughness Rz is, for example, 1 nm or more.

As described above, the optical adhesive sheet X has a transparent release liner 40 on the second surface 12 side of the optical adhesive sheet 10 and a surface protection film 50 on the liner. Such a configuration prevents environmental foreign matter from adhering to the transparent release liner 40 on the second surface 12 side of the optical adhesive sheet 10 until it is supplied to the optical article manufacturing process after the optical adhesive sheet X is manufactured. Also, the surface protection film 50 is suitable for preventing the transparent release liner 40 from being damaged.

In the optical adhesive sheet X, the fifth peel force between the transparent release liner 40 and the optical adhesive sheet 10 under the conditions of a peeling angle of 180° and a tensile speed of 300 mm/min (peeling of the transparent release liner 40 from the optical adhesive sheet 10 The second peeling force between the transparent release liner 20 and the optical adhesive sheet 10 is preferably smaller than the force required for peeling. With such a configuration, when the optical adhesive sheet X is used in the manufacturing process of an optical article, the optical adhesive sheet is kept attached to the second surface 12 of the optical adhesive sheet 10 while the transparent release liner 40 is maintained. Preferred for proper release of clear release liner 20 from first side 11 of 10 . The fifth peel force is preferably 0.03 N/50 mm or more, more preferably 0.05 N/50 mm or more, still more preferably 0.08 N/50 mm or more, still more preferably 0.12 N/50 mm or more, and particularly preferably 0.08 N/50 mm or more. It is 18 N/50 mm or more, preferably 2.0 N/50 mm or less, more preferably 1.5 N/50 mm or less, still more preferably 1.2 N/50 mm or less, and particularly preferably 1.0 N/50 mm or less.

The optical adhesive sheet 10 is a transparent adhesive sheet. The optical adhesive sheet 10 is a pressure-sensitive adhesive layer formed from an adhesive composition (first adhesive composition). The first PSA composition contains a base polymer.

The base polymer is an adhesive component for developing adhesiveness in the optical adhesive sheet 10 . The base polymer exhibits rubber elasticity in the room temperature range. Base polymers include, for example, acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluoropolymers. From the viewpoint of ensuring good transparency and adhesiveness in the optical adhesive sheet 10, an acrylic base polymer is preferably used as the base polymer.

The acrylic base polymer (first acrylic base polymer) is a copolymer of a monomer component (first monomer component) containing 50% by mass or more of (meth)acrylic acid alkyl ester. "(Meth)acrylic acid" means acrylic acid and/or methacrylic acid.

As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, that is, a (meth)acrylic acid C _1-20 alkyl ester is preferably used. The (meth)acrylic acid alkyl ester may have a linear or branched alkyl group, or may have a cyclic alkyl group such as an alicyclic alkyl group.

Examples of (meth)acrylic acid alkyl esters having a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate. , s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, (meth)acrylate Heptyl acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, (meth) ) isodecyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, isotridecyl (meth) acrylate, tetradecyl (meth) acrylate, isotetradecyl (meth) acrylate, pentadecyl (meth) acrylate, ( cetyl meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, and nonadecyl (meth)acrylate.

Examples of (meth)acrylic acid alkyl esters having an alicyclic alkyl group include (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring, and tricyclic (Meth)acrylic acid esters having the above aliphatic hydrocarbon ring can be mentioned. Cycloalkyl (meth)acrylates include, for example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Examples of (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring include isobornyl (meth)acrylate. (Meth)acrylic esters having a tricyclic or higher aliphatic hydrocarbon ring include, for example, dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate , 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

The amount of the (meth)acrylic acid alkyl ester relative to a total of 100 parts by mass of the first monomer component is, for example, 60 parts by mass or more and, for example, 100 parts by mass or less.

The first acrylic base polymer preferably contains a polar group-containing monomer as the first monomer component in addition to the (meth)acrylic acid alkyl ester described above. Polar group-containing monomers include, for example, hydroxyl group-containing monomers, carboxy group-containing monomers, and nitrogen-containing monomers. By including the polar group-containing monomer in the first monomer component, the cohesive force of the polymer tends to be enhanced, and the adhesion retention at high temperatures tends to be improved. In addition, when a cross-linking structure is introduced into the first acrylic base polymer with a cross-linking agent such as an isocyanate cross-linking agent or an epoxy cross-linking agent, the hydroxy group or the carboxy group serves as the introduction point of the cross-linking structure.

Examples of hydroxy group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, ( 8-hydroxyoctyl meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate.

Carboxy group-containing monomers include, for example, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

Nitrogen-containing monomers include, for example, nitrogen-containing vinyl monomers and cyanoacrylate monomers. Nitrogen-containing vinylic monomers include, for example, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, and N-vinylcaprolactam. Cyanoacrylate monomers include, for example, acrylonitrile and methacrylonitrile.

From the viewpoint of ensuring good adhesive strength in the optical adhesive sheet 10, the amount of the polar group-containing monomer relative to the total 100 parts by mass of the first monomer component is, for example, 5 parts by mass or more and, for example, 25 parts by mass or less. .

As a method for introducing a crosslinked structure into a base polymer, for example, after polymerizing a base polymer having a functional group capable of reacting with a crosslinker, a method of adding a crosslinker and reacting the base polymer and the crosslinker (Second 1 method), and a method of introducing a branched structure (crosslinked structure) into the polymer chain by including a polyfunctional compound in the polymerization component of the base polymer (second method). These may be used in combination to introduce multiple types of crosslinked structures into the base polymer.

In the first method, a cross-linked structure is introduced into the base polymer by adding a cross-linking agent to the polymerized base polymer and heating as necessary. Cross-linking agents include compounds that react with functional groups (eg, hydroxy and carboxy groups) contained in the base polymer. Crosslinkers include, for example, isocyanate crosslinkers, epoxy crosslinkers, oxazoline crosslinkers, aziridine crosslinkers, carbodiimide crosslinkers, and metal chelate crosslinkers.

As the cross-linking agent in the first method, an isocyanate cross-linking agent and an epoxy cross-linking agent are used because they are highly reactive with the functional groups (e.g., hydroxy groups and carboxy groups) of the base polymer and facilitate the introduction of a cross-linked structure. preferable. These cross-linking agents react with functional groups (eg, hydroxy groups and carboxy groups) introduced into the base polymer to form a cross-linked structure. For acid-free pressure-sensitive adhesives in which the base polymer does not contain carboxyl groups, it is preferable to use an isocyanate cross-linking agent to form a cross-linked structure by reacting the hydroxy groups in the base polymer with the isocyanate cross-linking agent.

In the second method, the first monomer component constituting the first acrylic base polymer and the total amount of the polyfunctional compound for introducing the crosslinked structure may be reacted (polymerized) at once, or in multiple stages. It may be polymerized. In the multistage polymerization method, for example, first, a monofunctional monomer constituting the base polymer is polymerized (prepolymerized) to prepare a partially polymerized product (prepolymer composition). Next, a polyfunctional compound such as a polyfunctional (meth)acrylate is added to the prepolymer composition, and the prepolymer composition and the polyfunctional monomer are polymerized (main polymerization). The prepolymer composition is a partially polymerized product containing a polymer with a low degree of polymerization and unreacted monomers.

Examples of polyfunctional compounds used for introducing a crosslinked structure include compounds containing two or more polymerizable functional groups (ethylenically unsaturated groups) having unsaturated double bonds in one molecule. As the polyfunctional compound, polyfunctional (meth)acrylates are preferred because they are easily copolymerized with the first monomer component of the first acrylic base polymer. When introducing a branched (crosslinked) structure by active energy ray polymerization (photopolymerization), polyfunctional acrylates are preferred.

Polyfunctional (meth)acrylates include, for example, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, bisphenol A ethylene oxide-modified di(meth)acrylate, bisphenol A Propylene oxide-modified di(meth)acrylate, alkanediol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol Di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol poly( meth)acrylates, dipentaerythritol hexa(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin di(meth)acrylate, epoxy (meth)acrylate, butadiene (meth)acrylate, and isoprene (meth)acrylate. be done.

Examples of polymerization methods for the first acrylic base polymer include solution polymerization, active energy ray polymerization, bulk polymerization, and emulsion polymerization. Solution polymerization and active energy ray polymerization (for example, UV polymerization) are preferred from the viewpoints of transparency, water resistance, and cost of the pressure-sensitive adhesive. Solvents for solution polymerization include, for example, ethyl acetate and toluene.

In preparing the first acrylic base polymer, a polymerization initiator may be used depending on the type of polymerization reaction. Polymerization initiators include, for example, photopolymerization initiators and thermal polymerization initiators. Examples of photopolymerization initiators include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, and photoactive oxime-based photopolymerization initiators. benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator, benzophenone-based photopolymerization initiator, ketal-based photopolymerization initiator, thioxanthone-based photopolymerization initiator, and acylphosphine oxide-based photopolymerization initiator. be done. Thermal polymerization initiators include, for example, azo initiators, peroxide initiators, and redox initiators obtained by combining a peroxide and a reducing agent (for example, a combination of persulfate and sodium hydrogen sulfite, and combinations of peroxides and sodium ascorbate).

In polymerization, a chain transfer agent and a polymerization inhibitor (polymerization retarder) may be used, for example, from the viewpoint of molecular weight adjustment. Examples of chain transfer agents include thiols such as α-thioglycerol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. , and α-methylstyrene dimer.

In the first pressure-sensitive adhesive composition, the content of the first acrylic base polymer (or prepolymer composition) relative to the total non-volatile content is preferably 50% by mass or more, more preferably 70% by mass, and 80% by mass. % or more, and particularly preferably 90 mass % or more.

The first pressure-sensitive adhesive composition may contain other components than those mentioned above. Other components include, for example, silane coupling agents, tackifiers, plasticizers, softeners, antidegradants, fillers, colorants, UV absorbers, antioxidants, surfactants, and antistatic agents. mentioned.

The thickness of the optical adhesive sheet 10 is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of ensuring sufficient adhesion to the adherend. From the viewpoint of handleability of the optical adhesive sheet 10, the thickness of the optical adhesive sheet 10 is preferably 300 μm or less, more preferably 200 μm or less.

The haze of the optical adhesive sheet 10 is preferably 3% or less, more preferably 2% or less. The haze of the optical adhesive sheet 10 can be measured using a haze meter according to JIS K7136 (2000). Examples of the haze meter include "NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd. and "HM-150 type" manufactured by Murakami Color Research Laboratory.

The transmittance of light emitted from the white LED light source in the optical adhesive sheet 10 is, for example, 50% or more, preferably 80% or more, and more preferably 90% or more. Such a configuration is preferable from the viewpoint of appropriately performing a foreign matter inspection using a white LED light source. In addition, the infrared transmittance of the optical adhesive sheet 10 is, for example, 50% or more, preferably 80% or more, and more preferably 90% or more. Such a configuration is preferable from the viewpoint of appropriately performing a foreign matter inspection using infrared rays.

The transparent release liner 20 is a flexible transparent resin film. Examples of materials for the resin film include polyolefin, polyester, polyamide, polyimide, polyvinyl chloride, polyvinylidene chloride, cellulose, modified cellulose, polystyrene, and polycarbonate. Examples of polyolefin include polyethylene, polypropylene, cycloolefin polymer (COP), poly-1-butene, poly-4-methyl-1-pentene, ethylene/propylene copolymer, ethylene/1-butene copolymer, ethylene - vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, and ethylene-vinyl alcohol copolymers. Polyesters include, for example, polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Polyamides include, for example, polyamide 6, polyamide 6,6, and partially aromatic polyamides. Examples of modified cellulose include triacetyl cellulose (TAC). These resin materials may be used alone, or two or more of them may be used in combination. As a material for the transparent release liner 20, a material with a high degree of cleanliness that is used for optical purposes is preferable. From the viewpoint of obtaining a transparent release liner 20 with a high degree of cleanliness, polyolefin is preferably used as the material for the transparent release liner 20, and COP is more preferably used.

Also, the resin material preferably contains no or substantially no filler. On the other hand, when the resin material contains a filler, the filler is preferably a nanofiller (nanofiller refers to particles with a maximum length of 100 nm or less). These configurations are preferable from the viewpoint of obtaining a transparent release liner 20 with a high degree of cleanness.

From the viewpoint of ensuring the strength of the transparent release liner 20, the thickness of the transparent release liner 20 is preferably 5 µm or more, more preferably 10 µm or more, and more preferably 20 µm or more. From the viewpoint of ensuring appropriate flexibility in the transparent release liner 20, the thickness of the transparent release liner 20 is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less.

The haze of the transparent release liner 20 is preferably 3% or less, more preferably 2% or less, even more preferably 1% or less. The haze of the transparent release liner 20 can be measured using a haze meter according to JIS K7136 (2000).

The transmittance of the light emitted from the white LED light source in the transparent release liner 20 is, for example, 50% or more, preferably 80% or more, and more preferably 90% or more. Such a configuration is preferable from the viewpoint of appropriately performing a foreign matter inspection using a white LED light source. The infrared transmittance of the transparent release liner 20 is, for example, 50% or higher, preferably 80% or higher, and more preferably 90% or higher. Such a configuration is preferable from the viewpoint of appropriately performing a foreign matter inspection using infrared rays.

The surface protection film 30 includes a base film 31 and an adhesive layer 32 on the base film 31 in this embodiment. In the surface protection film 30, the adhesive layer 32 forms an adhesive surface 30a.

The base film 31 is a flexible transparent resin film. Examples of materials for the resin film include the materials described above as materials for the resin film of the transparent release liner 20 . The thickness of the base film 31 is, for example, preferably 5 μm or more, more preferably 10 μm or more, and more preferably 20 μm or more, from the viewpoint of ensuring the strength of the surface protection film 30 . From the viewpoint of ensuring appropriate flexibility in the surface protection film 30, the thickness of the surface protection film 30 is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less.

The adhesive layer 32 is a pressure-sensitive adhesive layer formed from an adhesive composition (second adhesive composition). The second PSA composition contains a base polymer. The base polymer includes the base polymer described above with respect to the first pressure-sensitive adhesive composition. From the viewpoint of ensuring good transparency and adhesiveness in the pressure-sensitive adhesive layer 32, an acrylic base polymer (second acrylic base polymer) is preferably used as the base polymer of the second pressure-sensitive adhesive composition. Examples of the monomer component forming the second acrylic base polymer (second monomer component) include the monomer components described above as the first monomer component forming the first acrylic base polymer in the optical adhesive sheet 10 .

The second monomer component, as the (meth)acrylic acid alkyl ester, preferably contains a (meth)acrylic acid alkyl ester having an alkyl group having 3 to 10 carbon atoms, more preferably butyl acrylate and 2- At least one selected from the group consisting of ethylhexyl. The amount of (meth)acrylic acid alkyl ester having an alkyl group having 3 to 10 carbon atoms is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and still more preferably 100 parts by mass in total of the second monomer component. It is 93 parts by mass or more and, for example, 100 parts by mass or less, preferably 99 parts by mass or less, more preferably 98 parts by mass or less.

As a polar group-containing monomer, the second monomer component preferably contains at least one selected from the group consisting of a hydroxyl group-containing monomer and a carboxy group-containing monomer, more preferably acrylic acid and 2-hydroxy acrylate. At least one selected from the group consisting of ethyl. The amount of the polar group-containing monomer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, and preferably 10 parts by mass with respect to the total 100 parts by mass of the second monomer component. parts or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less.

The thickness of the adhesive layer 32 is preferably 1 µm or more, more preferably 3 µm or more, still more preferably 5 µm or more, and is preferably 30 µm or less, more preferably 25 µm or less, and still more preferably 20 µm or less.

The transparent release liner 40 is a flexible transparent resin film. The material, thickness, haze and transmittance of clear release liner 40 are similar to the material, thickness, haze and transmittance described above for clear release liner 20 .

The transparent release liner 40 preferably has a release layer on the optical adhesive sheet 10 side. The release layer is a layer for ensuring releasability of the transparent release liner 40 from the surface of the optical adhesive sheet 10 . Materials for the release layer include, for example, silicone resins, long-chain alkyl resins, and fatty acid amide resins. These resins may contain fluorine atoms in polymer side chains. For example, the silicone resin may be a fluorinated silicone resin containing fluorine atoms in side chains. When the transparent release liner 40 has a release layer on the optical adhesive sheet 10 side, methods for adjusting the release force between the transparent release liner 40 and the optical adhesive sheet 10 include, for example, the type of release layer material and adjusting the concentration of the release layer material.

The surface protective film 50 includes a base film 51 and an adhesive layer 52 on the base film 51 in this embodiment. In the surface protection film 50, the adhesive layer 52 forms an adhesive surface 50a.

The base film 51 is a flexible transparent resin film. Examples of materials for the resin film include the materials described above as materials for the resin film of the transparent release liner 20 . The thickness of the base film 51 is, for example, preferably 5 μm or more, more preferably 10 μm or more, and more preferably 20 μm or more, from the viewpoint of ensuring the strength of the surface protection film 50 . From the viewpoint of ensuring appropriate flexibility in the surface protection film 50, the thickness of the surface protection film 50 is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less.

The adhesive layer 52 is a pressure-sensitive adhesive layer formed from an adhesive composition (third adhesive composition). The third PSA composition contains a base polymer. The base polymer includes the base polymer described above with respect to the first pressure-sensitive adhesive composition. From the viewpoint of ensuring good transparency and adhesiveness in the pressure-sensitive adhesive layer 52, an acrylic base polymer (third acrylic base polymer) is preferably used as the base polymer of the third pressure-sensitive adhesive composition. Examples of the monomer component forming the third acrylic base polymer (third monomer component) include the monomer components described above as the first monomer component forming the first acrylic base polymer in the optical adhesive sheet 10 .

The third monomer component, as the (meth)acrylic acid alkyl ester, preferably contains a (meth)acrylic acid alkyl ester having an alkyl group having 3 to 10 carbon atoms, more preferably butyl acrylate and 2- At least one selected from the group consisting of ethylhexyl. The amount of (meth)acrylic acid alkyl ester having an alkyl group having 3 to 10 carbon atoms is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and still more preferably 100 parts by mass of the total of the third monomer component. It is 93 parts by mass or more and, for example, 100 parts by mass or less, preferably 99 parts by mass or less, more preferably 98 parts by mass or less.

As a polar group-containing monomer, the third monomer component preferably contains at least one selected from the group consisting of a hydroxyl group-containing monomer and a carboxy group-containing monomer, more preferably acrylic acid and 2-hydroxy acrylate. At least one selected from the group consisting of ethyl. The amount of the polar group-containing monomer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, and preferably 10 parts by mass with respect to the total 100 parts by mass of the third monomer component. parts or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less.

The thickness of the adhesive layer 52 is preferably 1 µm or more, more preferably 3 µm or more, still more preferably 5 µm or more, and is preferably 30 µm or less, more preferably 25 µm or less, and still more preferably 20 µm or less.

The optical adhesive sheet X can be produced, for example, by preparing the optical adhesive sheet 10 with the

transparent release liners

20 and 40 and the surface

protective films

30 and 50, respectively, and then laminating them together. The optical adhesive sheet X is preferably manufactured in a clean room.
The higher the air cleanliness in the production line of the optical adhesive sheet X (for example, the air cleanliness in the clean room), the smaller the environmental foreign matter inside and on the surface of the manufactured optical adhesive sheet X, and the smaller the size of the environmental foreign matter. The air cleanliness of the production line is preferably class 3 or less, more preferably class 2 or less, and even more preferably class 1 in the ISO 14644-1 standard.

The manufacturing method of the optical adhesive sheet 10 with the

transparent release liners

20, 40 is, for example, as follows.

First, the first pressure-sensitive adhesive composition described above is applied onto the transparent release liner 20 to form a coating film, and then the coating film is dried. Examples of the method of applying the first pressure-sensitive adhesive composition include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, Lip coating and die coating can be mentioned (the same applies to the coating method of the pressure-sensitive adhesive composition, which will be described later). When the first pressure-sensitive adhesive composition contains a cross-linking agent, the cross-linking reaction proceeds simultaneously with the above-described drying or by subsequent aging. Aging conditions are appropriately set according to the type of cross-linking agent. Also, before or after aging, a further transparent release liner 40 is laminated onto the optical adhesive sheet 10 on the transparent release liner 20 .

When the first pressure-sensitive adhesive composition is a photopolymerizable composition containing a prepolymer composition, a polyfunctional compound, etc., after applying the first pressure-sensitive adhesive composition on the transparent release liner 20 to form a coating film Photocuring is performed by irradiating the coating film with actinic rays. When performing photocuring, a transparent release liner 40 is laminated on the coating film, and the coating film is sandwiched between the two release liners and irradiated with actinic rays to prevent polymerization inhibition due to oxygen. preferable.

Actinic rays are selected according to the types of monomer components, polymerizable components (for example, polyfunctional (meth)acrylates), and photopolymerization initiators. Generally, ultraviolet and/or short wavelength visible light is used. The integrated light quantity of the irradiation light is, for example, about 100 to 5000 mJ/cm ² . As a light source for light irradiation, a light source capable of irradiating light in the wavelength range to which the photopolymerization initiator contained in the pressure-sensitive adhesive composition is sensitive is used. Light sources include, for example, LED light sources, high pressure mercury lamps, ultra high pressure mercury lamps, metal halide lamps, and xenon lamps.

As described above, the optical adhesive sheet 10 with the

transparent release liners

20 and 40 can be manufactured.

The surface protection film 30 is formed, for example, by applying the above-described second adhesive composition on the base film 31 to form a coating film, and then drying the coating film to form the adhesive layer 32. can be manufactured.

The surface protection film 50 is formed, for example, by applying the above-described third adhesive composition on the base film 51 to form a coating film, and then drying the coating film to form the adhesive layer 52. can be manufactured.

Then, the optical adhesive sheet 10 with the

transparent release liners

20 and 40 is laminated with the surface protective film 30 on the side of the transparent release liner 20 with the adhesive layer 32 , and the surface protective film 50 is transparent with the adhesive layer 52 . It is attached to the release liner 40 side. Thereby, the optical adhesive sheet X is obtained.

The optical adhesive sheet X may include a polarizer film 60 instead of the transparent release liner 40 and surface protective film 50, as shown in FIG. The optical adhesive sheet X shown in FIG. 2 includes a surface protection film 30, a transparent release liner 20, an optical adhesive sheet 10, and a polarizer film 60 in the thickness direction H in this order. The optical adhesive sheet 10 is bonded to the polarizer film 60 . According to such optical adhesive sheet X, the polarizer film with an adhesive layer, in which an adhesive layer is formed on the surface of the polarizer film 60 by the optical adhesive sheet 10, is adjusted to the degree of cleanness of the optical adhesive sheet 10 (adhesive layer). can be supplied to the optical article manufacturing process in a state of high

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples. In addition, the specific numerical values such as the compounding amount (content), physical property values, parameters, etc. described below are the corresponding compounding amounts ( content), physical property values, parameters, etc., upper limits (values defined as “less than” or “less than”) or lower limits (values defined as “greater than” or “greater than”).

[Preparation of surface protective film SPV1]
<Adjustment of first acrylic polymer>
96.2 parts by mass of 2-ethylhexyl acrylate (2EHA) and 3.8 parts by mass of 2-hydroxyethyl acrylate (HEA) were placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube. parts, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and 150 parts by mass of ethyl acetate as a solvent, at 65 ° C. for 6 hours, Stirred under a nitrogen atmosphere (polymerization reaction). As a result, a first polymer solution (solid concentration: 40% by mass) containing the first acrylic polymer was obtained. The weight average molecular weight of the first acrylic polymer was 540,000.

<Preparation of adhesive composition>
After adjusting the solid content concentration to 20% by mass by adding ethyl acetate to the first polymer solution, a cross-linking agent (product name “Coronate HX”, isocyanate of hexamethylene diisocyanate) is added to the polymer solution per 100 parts by mass of the first acrylic polymer. Nurate body, manufactured by Tosoh) (3 parts by mass) and 0.03 parts by mass of dibutyltin dilaurate as a crosslinking catalyst were added and mixed to obtain a first pressure-sensitive adhesive composition.

<Formation of adhesive layer>
After corona-treating one side of a polyethylene terephthalate (PET) film (product name "Diafoil T100C-38", thickness 38 μm, manufactured by Mitsubishi Chemical), the first adhesive composition was applied to the corona-treated side of the PET film. A coating was formed. Next, the coating film on the PET film was dried by heating at 130° C. for 2 minutes to form a first pressure-sensitive adhesive layer with a thickness of 23 μm.

A surface protective film SPV1 was produced as described above. The surface protective film SPV1 has a laminate structure of a PET film and a first adhesive layer (thickness 23 μm, first acrylic polymer), and has an adhesive surface on one side.

[Preparation of surface protective film SPV2]
A surface protective film SPV2 was produced in the same manner as the surface protective film SPV1 except for the following. In the preparation of the pressure-sensitive adhesive composition, the amount of dibutyltin dilaurate was set to 0.04 parts by mass. In forming the adhesive layer, the thickness of the adhesive layer formed on the PET film was set to 10 μm.

The surface protective film SPV2 has a laminated structure of a PET film and a second adhesive layer (thickness 10 μm, first acrylic polymer), and has an adhesive surface on one side.

[Preparation of surface protective film SPV3]
<Adjustment of second acrylic polymer>
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 95 parts by mass of butyl acrylate (BA), 5 parts by mass of acrylic acid (AA), and AIBN0 as a thermal polymerization initiator. A mixture containing .2 parts by weight and 186 parts by weight of ethyl acetate as solvent was stirred at 63° C. for 10 hours under a nitrogen atmosphere (polymerization reaction). As a result, a second polymer solution (solid concentration: 35% by mass) containing the second acrylic polymer was obtained. The weight average molecular weight of the second acrylic polymer was 500,000.

<Preparation of adhesive composition>
After adjusting the solid content concentration to 20% by mass by adding ethyl acetate to the second polymer solution, a cross-linking agent (product name “Tetrad C”, 1,3-bis (N,N-diglycidylaminomethyl)cyclohexane, manufactured by Mitsubishi Gas Chemical) (5 parts by mass) was added and mixed to obtain a second adhesive composition.

<Formation of adhesive layer>
After one side of a PET film (product name “Diafoil T100C-38”, thickness 38 μm, manufactured by Mitsubishi Chemical) is subjected to corona treatment, a second adhesive composition is applied to the corona-treated surface of the PET film to form a coating film. bottom. Next, the coating film on the PET film was dried by heating at 130° C. for 2 minutes to form a third pressure-sensitive adhesive layer with a thickness of 5 μm.

A surface protective film SPV3 was produced as described above. The surface protection film SPV3 has a laminate structure of a PET film and a third adhesive layer (thickness 5 μm, second acrylic polymer), and has an adhesive surface on one side.

[Example 1]
A covered optical pressure-sensitive adhesive sheet was produced in a clean room as follows.

First, a cycloolefin polymer (COP) film (trade name "Zeonor Film ZF16", thickness 50 μm, manufactured by Nippon Zeon Corporation) was prepared as a base film for the first transparent release liner. Next, the adhesive surface side of the surface protection film SPV3 was attached to one surface of this COP film. Next, a first silicone release layer was formed on the other surface of the COP film. Specifically, first, 30 parts by mass of an addition-type silicone composition (trade name “LTC761”, manufactured by Dow Corning Toray) and 0 part of a silicone dispersion (trade name “BY 24-850” manufactured by Dow Corning Toray) A mixture of 9 parts by mass and 2 parts by mass of a platinum catalyst for curing silicone (trade name “SRX 212” manufactured by Dow Corning Toray) was added to a mixed solvent of toluene and hexane (the volume ratio of toluene and hexane was 1:1). 1) to prepare a release agent solution. Next, this solution was applied to the other side of the COP film and dried by heating in a hot air dryer at 130° C. for 1 minute. As a result, a first transparent release liner with surface protection film SPV3 was obtained.

On the other hand, a cycloolefin polymer (COP) film (trade name "Zeonor Film ZF16", thickness 50 μm, manufactured by Nippon Zeon) was prepared as a base film for the second transparent release liner. Next, the adhesive surface side of the surface protective film SPV1 was attached to one surface of this COP film. Next, a second silicone release layer was formed on the other surface of the COP film. As a result, a second transparent release liner with surface protection film SPV1 was obtained. The second silicone-based release layer has a different composition and thickness than the first silicone-based release layer of the first transparent release liner, and has a higher release force than the first silicone-based release layer.

Next, in a clean room, a coating film (thickness: 50 μm) was formed by applying an ultraviolet-curing pressure-sensitive adhesive composition to the surface of the first transparent release liner on the release layer side. Next, the release layer side surface of the second transparent release liner was attached to the exposed surface of the coating film to obtain a laminate. This laminate was irradiated with ultraviolet rays from the side of the second transparent release liner to photo-cure the adhesive composition coating film to form an adhesive layer. As a light source for ultraviolet irradiation, a black light whose position was adjusted so that the irradiation intensity on the irradiated surface immediately below the lamp was 5 mW/cm ² was used (the same applies to ultraviolet irradiation described later).

The covered optical pressure-sensitive adhesive sheet of Example 1 was produced as described above. The covered optical pressure-sensitive adhesive sheet of Example 1 comprises a surface protection film SPV3, a first transparent release liner (light release liner), an optical pressure-sensitive adhesive sheet, a second transparent release liner (heavy release liner), and a surface protection film SPV1. are provided in order in the thickness direction.

[Example 2]
A covered optical pressure-sensitive adhesive sheet of Example 2 was produced in the same manner as the covered optical pressure-sensitive adhesive sheet of Example 1, except that the surface protection film SPV2 was used instead of the surface protection film SPV1.

The covered optical pressure-sensitive adhesive sheet of Example 2 comprises a surface protection film SPV3, a first transparent release liner (light release liner), an optical pressure-sensitive adhesive sheet, a second transparent release liner (heavy release liner), and a surface protection film SPV2. are provided in order in the thickness direction.

[Example 3]
A covered optical pressure-sensitive adhesive sheet was produced in a clean room as follows.

First, a first transparent release liner with a surface protective film SPV3 was produced in the same manner as the first transparent release liner with a surface protective film SPV3 in the covered optical pressure-sensitive adhesive sheet of Example 1.

On the other hand, a UV-curable pressure-sensitive adhesive composition was applied to the release layer side surface of a predetermined first release liner having a release layer on one side to form a coating film (thickness: 50 µm). Next, the release layer side surface of a predetermined second release liner having a release layer on one side was adhered to the exposed surface of the coating film to obtain a laminate. This laminate was irradiated with ultraviolet rays from the second release liner side to photo-cure the adhesive composition coating film to form an adhesive layer. Next, after peeling off the second release liner from the adhesive layer, a polarizer film (thickness: 34 μm) was attached to the exposed adhesive layer. Next, after peeling off the first release liner from the pressure-sensitive adhesive layer with the polarizer film, the release layer side of the first transparent release liner with the surface protective film SPV3 was attached to the exposed pressure-sensitive adhesive layer.

The covered optical pressure-sensitive adhesive sheet of Example 3 was produced as described above. The covered optical pressure-sensitive adhesive sheet of Example 3 comprises a surface protection film SPV3, a first transparent release liner, an optical pressure-sensitive adhesive sheet, and a polarizer film in this order in the thickness direction.

[Example 4]
A covered optical pressure-sensitive adhesive sheet was produced in a clean room as follows.

First, as a base film for the first transparent release liner, a COP film (trade name "Zeonor Film ZF16", thickness 50 μm, manufactured by Nippon Zeon) was prepared. Next, the adhesive surface side of a surface protection film SPV4 (product name: "PEARL PREMIUM", Tredeger) having an adhesive surface on one side was attached to one surface of this COP film. Next, a first silicone-based release layer was formed on the other surface of the COP film (the method of forming the first silicone-based release layer is the same as described above with respect to Example 1). As a result, a first transparent release liner with surface protection film SPV4 was obtained.

Then, in the same manner as the covered optical pressure-sensitive adhesive sheet of Example 3, except that the first transparent release liner with surface protective film SPV4 was used instead of the first transparent release liner with surface protective film SPV3, Example 4 A covered optical pressure-sensitive adhesive sheet was produced. The covered optical pressure-sensitive adhesive sheet of Example 4 comprises a surface protective film SPV4, a first transparent release liner, an optical pressure-sensitive adhesive sheet, and a polarizer film in this order in the thickness direction.

[Comparative Example 1]
A covered optical pressure-sensitive adhesive sheet was produced in a clean room as follows.

First, two first transparent release liners with the surface protection film SPV1 described above with respect to Example 1 were produced. Next, in a clean room, a coating film (thickness: 50 μm) was formed by applying an ultraviolet-curing pressure-sensitive adhesive composition to the release layer-side surface of one of the first transparent release liners. Next, the release layer side surface of the other first transparent release liner was attached to the exposed surface of the coating film to obtain a laminate. This laminate was irradiated with ultraviolet rays from the other first transparent release liner side to photo-cure the adhesive composition coating film to form an adhesive layer.

A covered optical pressure-sensitive adhesive sheet of Comparative Example 1 was produced as described above. The covered optical pressure-sensitive adhesive sheet of Comparative Example 1 includes a surface protection film SPV1, a first transparent release liner, an optical pressure-sensitive adhesive sheet, a first transparent release liner, and a surface protection film SPV1 in order in the thickness direction.

<Release force between transparent release liner and surface protective film>
The peel force required to peel off the surface protective films SPV1 to SPV4 from the above-mentioned COP film (trade name “Zeonor Film ZF16”, thickness 50 μm, manufactured by Nippon Zeon) used as a transparent release liner was measured (first measurement). .

In preparing the test piece for measurement, first, the adhesive surface side of the surface protection film was attached to the COP film. In this lamination, the surface protection film was pressure-bonded to the COP film by reciprocating a 2-kg hand roller once under an environment of 23°C. Next, the strong adhesive layer side of a PET substrate having a strong adhesive layer formed on one side thereof was attached to the COP film side to obtain a laminate. Next, a test piece (width 50 mm×length 100 mm) was cut out from this laminate (PET substrate/strong adhesive layer/COP film/surface protection film). A test piece for measurement was produced as described above.

Next, after the test piece for measurement was allowed to stand at 23°C for 1 hour, a peel test was conducted in which the surface protective film of the test piece for measurement was peeled off from the COP film, and the peel force was measured. For this measurement, a tensile tester (product name “Autograph AG-50NX plus”, manufactured by Shimadzu Corporation) was used. In this measurement, the measurement temperature was 23° C., the peel angle was 180°, the tensile speed was 300 mm/min, and the peel length was 50 mm. The measured peel force is shown in Table 1 as a peel force f1 (N/50 mm). The peeling force f1 corresponds to the third peeling force in the present invention.

Also, the peeling force f1 for peeling the surface protective film SPV3 from the COP film is shown in Table 2 as the peeling force F1 in Examples 1, 2, and 3. The peeling force F1 is the force required to peel the first surface protective film from the first transparent release liner, and corresponds to the first peeling force in the present invention (the same applies to the peeling force F1 described later). The peeling force f1 for peeling the surface protective film SPV2 from the COP film is shown in Table 2 as the peeling force F3 in Example 2. The peeling force f1 for peeling the surface protective film SPV4 from the COP film is shown in Table 2 as the peeling force F1 in Example 4. The peeling force f1 for peeling the surface protective film SPV1 from the COP film is shown in Table 2 as the peeling force F1 in Comparative Example 1. The peeling force f1 for peeling the surface protective film SPV1 from the COP film is shown in Table 2 as the peeling force F3 in Example 1 and Comparative Example 1. The peeling force F3 is the force required to peel the second surface protective film from the second transparent release liner (the same applies to the peeling force F3 described later).

On the other hand, in the same manner as in the first measurement except for the following, COP film (trade name "Zeonor film ZF16", thickness 50 μm, manufactured by Nippon Zeon) Each peeling force required to peel the surface protection films SPV1 to SPV4 from was measured. The prepared test piece for measurement was stored at 50° C. for 2 weeks, then stored for 1 day at 23° C. and 50% relative humidity, and the peel strength of the test piece for measurement after such storage was measured. The measurement conditions are the same as those for the first measurement described above. The measured peel force is shown in Table 1 as a peel force f1' (N/50 mm). The peel force f1' corresponds to the fourth peel force in the present invention. Table 1 also shows the ratio of the peel force f1' to the peel force f1 (f1'/f1).

Also, the peeling force f1' for peeling the surface protective film SPV3 from the COP film is shown in Table 2 as the peeling force F1' in Examples 1, 2, and 3. The peeling force F1' is the peeling force for peeling the first surface protective film from the first transparent release liner after the heat storage (the same applies to the peeling force F1' described later). The peeling force f1' for peeling the surface protective film SPV4 from the COP film is shown in Table 2 as the peeling force F1' in Example 4. The peeling force f1' for peeling the surface protective film SPV1 from the COP film is shown in Table 2 as the peeling force F1' in Comparative Example 1.

<Gel fraction of adhesive layer of surface protective film>
The gel fraction of each adhesive layer of the surface protective films SPV1 to SPV3 was measured. Specifically, it is as follows.

First, about 0.1 g (mass: W ₁ mg) of adhesive sample was taken from the adhesive layer of the surface protection film. Next, the pressure-sensitive adhesive sample was wrapped in a tetrafluoroethylene resin porous membrane (mass: W ₂ mg) with an average pore size of 0.2 μm in the form of a purse, and the mouth was tied with a kite string (mass: W ₃ mg) and wrapped. got As the tetrafluoroethylene resin porous membrane, a porous membrane manufactured by Nitto Denko Corporation (trade name “Nitoflon NTF1122”) was used. The packets containing the adhesive samples were then placed in a 50 mL container, which was then filled with ethyl acetate (one container was used for each packet). After allowing this to stand at 23° C. for 7 days, the package was removed from the container and dried at 130° C. for 2 hours. The mass (W ₄ mg) of the packet was then determined. Then, the gel fraction of the pressure-sensitive adhesive layer was calculated by substituting the values of W ₁ to W ₄ into the following formula.
The values are shown in Table 1.

Gel fraction (%) = [( _W4 - _W2 - _W3 )/ _W1 ] x 100

<Release force between optical adhesive sheet and transparent release liner>
For each of the covered optical pressure-sensitive adhesive sheets of Examples 1-4, the release force required to peel the first transparent release liner from the optical pressure-sensitive adhesive sheet was measured. Specifically, first, a test piece for measurement was produced. In preparing the test piece, first, a sheet piece (width 50 mm x length 100 mm) was cut out from the covered optical pressure-sensitive adhesive sheet. Next, the surface protective films on both sides of the sheet piece were peeled off. Thus, a test piece for measurement was obtained. Next, after the test piece was allowed to stand at 23° C. for 60 minutes, a peel test was conducted by peeling the first transparent release liner of the test piece from the optical adhesive sheet, and the peel force was measured (second measurement). For this measurement, a tensile tester (product name “Autograph AG-50NX plus”, manufactured by Shimadzu Corporation) was used. In this measurement, the measurement temperature was 23° C., the peel angle was 180°, the tensile speed was 300 mm/min, and the peel length was 50 mm. The measured peel force is shown in Table 2 as peel force F2 (N/50 mm) in Examples 1-4. The peel force F2 is the force required to peel the first transparent release liner from the optical adhesive sheet (that is, the second peel force) (the same applies to the peel force F2 described later).

On the other hand, for each of the covered optical pressure-sensitive adhesive sheets of Examples 1 and 2, the peel force required to peel off the second transparent release liner from the optical pressure-sensitive adhesive sheet was measured. Specifically, first, a test piece for measurement was produced. In preparing the test piece, first, the first transparent release liner was peeled off together with the surface protective film thereon from the covered optical pressure-sensitive adhesive sheet. Next, a PET base material was attached to the exposed surface of the optical adhesive sheet exposed by the peeling to obtain a laminate. In this bonding, the PET base material was pressure-bonded to the optical adhesive sheet by reciprocating a 2-kg hand roller once under an environment of 23°C. Next, a test piece (width 50 mm×length 100 mm) was cut out from this laminate. Thus, a test piece for measurement was obtained. Next, after the test piece was allowed to stand at 23° C. for 60 minutes, a peel test was conducted by peeling the second transparent release liner of the test piece from the optical adhesive sheet, and the peel force was measured. Specifically, it is similar to the second measurement. The measured peel force is shown in Table 2 as peel force F4 (N/50 mm) in Examples 1 and 2. The peeling force F4 corresponds to the fifth peeling force in the present invention.

On the other hand, in the covered optical pressure-sensitive adhesive sheet of Comparative Example 1, the peel force required to peel one of the first transparent release liner from the optical pressure-sensitive adhesive sheet was measured. Specifically, first, a test piece for measurement was produced. In preparing the test piece, first, a sheet piece (width 50 mm x length 100 mm) was cut out from the covered optical pressure-sensitive adhesive sheet. Next, the surface protective films on both sides of the sheet piece were peeled off. Thus, a test piece for measurement was obtained. Next, after the test piece was allowed to stand at 23° C. for 60 minutes, a peel test was conducted by peeling one first transparent release liner of the test piece from the optical adhesive sheet, and the peel force was measured. Specifically, it is similar to the second measurement. The measured peel forces are shown in Table 2 as peel forces F2 and F4 (N/50 mm) in Comparative Example 1.

<Peelability evaluation of surface protective film>
In the covered optical pressure-sensitive adhesive sheets of Examples 1 to 4 and Comparative Example 1, the releasability of each surface protective film from the transparent release liner was examined.

Specifically, first, one of the surface protective films to be evaluated in the covered optical pressure-sensitive adhesive sheet was manually peeled off from the transparent release liner with which it was in contact. Regarding the releasability of the surface protective film, the case where the surface protective film could be peeled off while the transparent release liner remained on the optical adhesive sheet was evaluated as "good". When it was peeled off from the optical adhesive sheet, it was evaluated as "poor". Table 2 shows the evaluation results.

The covered optical pressure-sensitive adhesive sheet of the present invention is used, for example, as a supply material for optical pressure-sensitive adhesive sheets in the manufacturing process of display panels.

X optical adhesive sheet (covered optical adhesive sheet)
H: thickness direction 10: optical adhesive sheet 11: first surface 12: second surface 20, 40: transparent release liner 30, 50: surface

protective films

30a, 50a: adhesive surface 60: polarizer film

Claims

An optical adhesive sheet, a transparent release liner, and a surface protective film are provided in order in the thickness direction,
The optical adhesive sheet has a first surface and a second surface opposite to the first surface,
the transparent release liner is disposed on the first surface;
the surface protection film has an adhesive surface and is adhered to the transparent release liner with the adhesive surface;
The first peel force between the surface protective film and the transparent release liner under the conditions of a peel angle of 180° and a tensile speed of 300 mm/min is A covered optical pressure-sensitive adhesive sheet having a second peel force smaller than
After the surface protective film is attached to the cycloolefin polymer film, a peel force of 1.0 N/50 mm or less is applied to the cycloolefin polymer film under the conditions of a peel angle of 180° and a tensile speed of 300 mm/min. The covered optical pressure-sensitive adhesive sheet according to claim 1, comprising:
After the surface protection film is attached to the cycloolefin polymer film, it has a third peel force with respect to the cycloolefin polymer film under the conditions of a peel angle of 180° and a tensile speed of 300 mm/min,
After two weeks at 50° C. from bonding to the cycloolefin polymer film, the surface protection film exhibits a fourth peel force against the cycloolefin polymer film under the conditions of a peel angle of 180° and a tensile speed of 300 mm/min. death,
2. The covered optical pressure-sensitive adhesive sheet according to claim 1, wherein the ratio of said fourth peel force to said third peel force is 0.8 or more and 1.5 or less.
The covered optical pressure-sensitive adhesive sheet according to claim 1, wherein the surface protection film has a pressure-sensitive adhesive layer forming the pressure-sensitive adhesive surface, and the pressure-sensitive adhesive layer has a gel fraction of 80% or more.
The covered optical pressure-sensitive adhesive sheet according to claim 1, wherein the surface roughness Ra of the surface of the transparent release liner on the surface protective film side is 20 nm or less.
further comprising an additional transparent release liner and an additional surface protection film on the second surface side of the optical adhesive sheet;
the additional transparent release liner is disposed on the second side of the optical adhesive sheet;
The covered optical pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the additional surface protective film has an adhesive surface and is adhered to the additional transparent release liner with the adhesive surface. .
The covered optical adhesive sheet according to claim 6, wherein the second peel force is smaller than the fifth peel force under the conditions between the additional transparent release liner and the optical adhesive sheet.
The covered optical pressure-sensitive adhesive sheet according to any one of claims 1 to 5, further comprising a polarizer film arranged on said second surface of said optical pressure-sensitive adhesive sheet.