CN116430485A

CN116430485A - Optical laminate and coated optical film

Info

Publication number: CN116430485A
Application number: CN202211663675.5A
Authority: CN
Inventors: 三浦大生; 野田美菜子
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2021-12-24
Filing date: 2022-12-23
Publication date: 2023-07-14
Also published as: JP2023095056A; KR20230098051A; TW202332580A

Abstract

An optical laminate and a coated optical film suitable for shaping without cutting the coated film are provided. The optical laminate (X) is provided with a cover film (20), an adhesive layer (40), a functional optical film layer (10), an adhesive layer (50), and a pixel panel layer (30) in that order along the thickness direction (D). The product P of Young's modulus (MPa) at 23 ℃ and light transmittance (%) at 355nm and thickness (μm) of the cover film (20) ₁ Young's modulus (MPa) at 23 ℃ and wavelength 355nm greater than each layer (adhesive layer (40), functional optical film layer (10), adhesive layer (50) and pixel panel layer (30))The sum S of the products of the light transmittance (%) and the thickness (μm) ₁ . The coated optical film (Y) is used for an optical laminate (X) and comprises, in the thickness direction (D), a coating film (20), an adhesive layer (40), a functional optical film layer (10), and an adhesive layer (50) in that order.

Description

Optical laminate and coated optical film

Technical Field

The present invention relates to an optical laminate and a coated optical film.

Background

The display panel has a laminated structure including, for example, an optical member such as a pixel panel, a polarizing plate, and a surface coating layer. On the other hand, in smart phone applications and tablet terminal applications, development of display panels capable of being repeatedly folded (foldable) has been performed. In particular, the foldable display panel is capable of repeatedly deforming between a curved shape and a flat non-curved shape. In such a foldable display panel, each optical member in the laminated structure is manufactured as an optical member that can be repeatedly bent. A thin adhesive layer is used in the bonding between the optical members.

In the manufacturing process of the foldable display panel, an optical laminate for forming a part of the laminated structure is manufactured in advance. Such an optical stack is fed to a production line of foldable display panels. Examples of the optical laminate include an optical laminate including a pixel panel layer, an adhesive layer, a polarizing film, and a surface adhesive layer in this order in the thickness direction. The optical laminate is manufactured in a manner such that the surface adhesive layer is covered with a cover film. The cover film is peeled off from the surface adhesive layer at a predetermined timing. For example, patent document 1 below describes an optical laminate for flexible device applications such as a foldable display panel.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2021-91117

Disclosure of Invention

Problems to be solved by the invention

The adhesive layer in a flexible device is required to be highly soft so as to have sufficient follow-up property to an adherend and excellent stress relaxation property when the device is bent. However, the softer the adhesive layer, the more difficult it is to cut the optical laminate by a cutting blade at the time of the contour processing in the manufacturing process of the optical laminate with a cover film. This is because the adhesive layer will adhere to the cutting edge. Thus, it is conceivable to shape the optical laminate by laser light.

However, when the optical laminate with the cover film is cut by a laser in the thickness direction, thermal fusion between adjacent layers (thermal fusion also occurs between the surface adhesive layer and the cover film) occurs at the end face formed by the cutting. In order to separate the cover film from the surface adhesive layer at the cut end face where the heat fusion occurs, a larger force is required than in the case where the heat fusion does not occur. As a result, it is difficult to peel the cover film from the surface adhesive layer.

The present invention provides an optical laminate and a coated optical film suitable for shaping without cutting the coated film.

Solution for solving the problem

The invention [1 ]]Comprises an optical laminate comprising, in order in the thickness direction, a cover film, a first adhesive layer, a functional optical film layer, a second adhesive layer, and a pixel panel layer, wherein the cover film has a Young's modulus (MPa) at 23 ℃ multiplied by the product P of the light transmittance (%) at 355nm and the thickness (μm) ₁ Is greater than the sum S of the product of Young' S modulus (MPa) at 23 ℃ and light transmittance (%) and thickness (mum) of each layer at 355nm wavelength ₁ 。

The invention [2 ]]Comprises the above [1 ]]The optical laminate, wherein the product P ₁ Is 0.5X10 ⁷ The above.

The invention [3 ]]Comprises the above [1]]Or [2 ]]The optical laminate, wherein the product P ₁ Sum S with the above ₁ The difference is 1X 10 ⁷ The above.

The invention [4 ]]Comprises the above [1]]～[3]The optical laminate according to any one of claims, wherein the cover film has a product P of young's modulus (MPa) at 23 ℃ and light transmittance (%) at 355nm ₂ A total S of the product of Young' S modulus (MPa) at 23 ℃ and light transmittance (%) at 355nm of each layer is larger than that of the layers ₂ 。

The invention [5 ]]Comprises the above [4 ]]The optical laminate, wherein the product P ₂ Is 1X 10 ⁵ The above.

The invention [6]]Comprises the above [4 ]]Or [5 ]]The said processAn optical laminate, wherein the product P ₂ Sum S with the above ₂ The difference is 1X 10 ⁵ The above.

The invention [7] includes the optical laminate according to any one of the above [1] to [6], wherein the functional optical film is a polarizing film.

The invention [8] includes a coated optical film for use in the optical laminate of any one of [1] to [7], the coated optical film comprising, in order in a thickness direction, the coating film, the first adhesive layer, the functional optical film layer, and the second adhesive layer.

ADVANTAGEOUS EFFECTS OF INVENTION

In the optical laminate of the present invention, as described above, the product P of Young's modulus (MPa) at 23 ℃ and transmittance (%) at 355nm wavelength and thickness (μm) of the cover film is obtained ₁ A total S of products of Young' S modulus (MPa) at 23 ℃ and light transmittance (%) at 355nm and thickness (μm) of the respective layers (functional optical film layer, first adhesive layer/second adhesive layer, pixel panel layer) ₁ . That is, in the optical laminate, the easiness of dicing (laser dicing) by laser is significantly different between the cover film and each layer. The cover film is more difficult to laser cut than a portion from the pixel panel layer to the first adhesive layer. Such an optical laminate is suitable for shaping a portion from the pixel panel layer to the first adhesive layer by irradiating the pixel panel layer side with laser light in the thickness direction without cutting the cover film.

Drawings

FIG. 1 is a schematic cross-sectional view of one embodiment of an optical stack of the present invention.

Fig. 2 a to 2C show a method of processing the outer shape of the optical laminate. Fig. 2 a shows laser irradiation of an optical laminate. Fig. 2B shows the optical laminate after laser dicing. Fig. 2C shows the optical laminate after the unnecessary portion is removed.

Fig. 3 a and 3B illustrate an example of a method for manufacturing the optical layered body shown in fig. 1. Fig. 3 a shows a step of obtaining a coated optical film, and fig. 3B shows a step of bonding the coated optical film to a pixel panel layer.

Description of the reference numerals

X-ray laminate

Y-coated optical film

D thickness direction

10. Functional optical film layer

11. First surface

12. A second surface

20. Cover film

30. Pixel panel layer

40. Adhesive layer (first adhesive layer)

41. 51 adhesive surface

50. Adhesive layer (second adhesive layer)

Detailed Description

As shown in fig. 1, an optical laminate X, which is an embodiment of the optical laminate of the present invention, includes a functional optical film layer 10, a cover film 20, a pixel panel layer 30, an adhesive layer 40 (first adhesive layer), and an adhesive layer 50 (second adhesive layer). The optical laminate X has a sheet shape of a predetermined thickness, and extends in a direction (plane direction) orthogonal to the thickness direction D. Specifically, the optical laminate X includes, in order along the thickness direction D, a cover film 20, an adhesive layer 40, a functional optical film layer 10, an adhesive layer 50, and a pixel panel layer 30. The cover film 20 is in contact with the adhesive layer 40. The adhesive layer 40 is in contact with the functional optical film 10. The functional optical film 10 is in contact with the adhesive layer 50. The adhesive layer 40 is in contact with the pixel panel layer 30. Such an optical laminate X is an optically transparent laminate. The optical layered body X is disposed at a light passing portion in the flexible device. As the flexible device, for example, a flexible display panel can be cited. As the flexible display panel, for example, a foldable display panel and a rollable display panel can be cited. When the optical laminate X is supplied to a production line of flexible display panels, the cover film 20 is peeled off from the adhesive layer 40 at a predetermined timing.

In optical laminationIn the body X, the Young's modulus E (MPa) at 23 ℃ of the cover film 20 is multiplied by the product P of the light transmittance T (%) at 355nm and the thickness H (μm) ₁ (E x T x H) is greater than the sum S of Young' S modulus E (MPa) at 23 ℃ and the product of light transmittance T (%) and thickness H (μm) (E x T x H) at a wavelength of 355nm of each layer (functional optical film layer 10, pixel panel layer 30, adhesive layer 40, adhesive layer 50) ₁ . The respective measurement methods of young's modulus and light transmittance are described later for examples. Examples of the method for adjusting the light transmittance of the cover film 20 and the layers include changing the material, adding a light absorbing material to the material, and changing the thickness.

In this optical laminate X, the easiness of dicing (laser dicing) by laser is significantly different between the cover film 20 and each layer. The cover film 20 is more difficult to laser cut than the portion from the pixel panel layer 30 to the adhesive layer 40. Such an optical laminate X is suitable for performing contour processing on a portion from the pixel panel layer 30 to the adhesive layer 40 without cutting the cover film 20 by irradiating the pixel panel layer 30 side with laser light in the thickness direction D.

In the outline processing, as shown in fig. 2 a, the laser light R is irradiated to the pixel panel layer 30 side of the optical laminate X in the thickness direction D. As a result, as shown in fig. 2B, the portion of the optical laminate X from the pixel panel layer 30 to the adhesive layer 40 is cut. The cut end face 100 is formed at a portion from the pixel panel layer 30 to the adhesive layer 40. The cover film 20 is not cut. After this dicing, as shown in fig. 2C, unnecessary portions from the diced pixel panel layer 30 to the adhesive layer 40 can be removed. In the optical laminate X after such shaping, the cover film 20 has a projecting end portion 20A. The projecting end portion 20A projects in the face direction from the cut end face 100. The cover film 20 having the protruding end portion 20A is easily peeled from the adhesive layer 50.

From the standpoint of shaping the portion from the pixel panel layer 30 to the adhesive layer 40 without cutting the cover film 20, the product P ₁ And sum S ₁ Difference (P) ₁ -S ₁ ) Preferably 0.5X10 ⁷ The above is more preferably 1×10 ⁷ The above is more preferably 1.5X10 ⁷ The above is preferably 2×10 ⁷ The above. Difference (P) ₁ -S ₁ ) For example 20X 10 ⁷ The following is given.

From the viewpoint of suppressing laser processability of the cover film 20, the product P ₁ Preferably 0.5X10 ⁷ The above is more preferably 1×10 ⁷ The above is more preferably 1.5X10 ⁷ The above is more preferably 2×10 ⁷ The above. Product P ₁ For example 20X 10 ⁷ The following is given.

The product P of Young's modulus E (MPa) at 23 ℃ and light transmittance T (%) at 355nm of the cover film 20 ₂ (E×T) is preferably greater than the sum S of the products (E×T) of Young' S modulus E (MPa) at 23 ℃ and light transmittance T (%) at 355nm of the respective layers (functional optical film layer 10, pixel panel layer 30, adhesive layers 40, 50) ₂ . In this optical laminate X, the easiness of laser cutting of the cover film 20 is significantly different from that of the above layers. The cover film 20 is more difficult to laser cut than the portion from the pixel panel layer 30 to the adhesive layer 40. As shown in fig. 2, such an optical laminate X is suitable for performing contour processing on a portion from the pixel panel layer 30 to the adhesive layer 40 by irradiating the pixel panel layer 30 side with the laser light R in the thickness direction D without cutting the cover film 20.

Depending on the type of functional optical film layer 10, the optical laminate X may have a product P ₂ (E x T) is greater than total S ₂ The above-described constitution (second constitution) of (a) replaces the product P ₁ (E x T x H) is greater than the total S ₁ The above constitution (first constitution). When the functional optical film layer 10 is, for example, a polarizing film, a retardation film, or a combination thereof, the optical laminate X may preferably have the second configuration and optionally the first configuration.

From the standpoint of shaping the portion from the pixel panel layer 30 to the adhesive layer 40 without cutting the cover film 20, the product P ₂ And sum S ₂ Difference (P) ₂ -S ₂ ) Preferably 1X 10 ⁵ The above is more preferably 2×10 ⁵ The above is more preferably 3×10 ⁵ The above is particularly preferably 4×10 ⁵ The above. Difference (P) ₂ -S ₂ ) For example 20X 10 ⁵ The following is given.

From the viewpoint of suppressing laser processability of the cover film 20, the product P ₂ Preferably 1X 10 ⁵ The above is more preferably 2×10 ⁵ The above is more preferably 3×10 ⁵ The above is particularly preferably 4×10 ⁵ The above. Product P ₂ For example 20X 10 ⁵ The following is given.

As described above, the functional optical film layer 10 is a layer formed of a functional optical film. Examples of the functional optical film include a film-like polarizing plate (polarizing film), a retardation film, and a combination thereof.

Examples of the polarizing film include a hydrophilic polymer film subjected to dyeing treatment with a dichroic substance and subsequent stretching treatment. Examples of the dichroic substance include iodine and a dichroic dye. Examples of the hydrophilic polymer film include a polyvinyl alcohol (PVA) film, a partially formalized PVA film, and a partially saponified film of an ethylene-vinyl acetate copolymer. The polarizing film may be a polyene oriented film. Examples of the material of the polyene oriented film include a dehydrated product of PVA and a desalted product of polyvinyl chloride. The thickness of the functional optical film layer 10 as a polarizing film is preferably 2 μm or more, more preferably 4 μm or more, from the viewpoint of securing the function and strength of the functional optical film layer 10. The thickness of the functional optical film layer 10 as a polarizing film is preferably 10 μm or less, more preferably 8 μm or less, from the viewpoint of thinning the optical laminate X.

As the polarizer, a thin polarizer having a thickness of 10 μm or less can be used. Examples of the thin polarizer include polarizers described in Japanese patent application laid-open No. 51-069644, japanese patent application laid-open No. 2000-338329, WO2010/100917, japanese patent No. 4691205 and Japanese patent No. 4751481.

Examples of the retardation film include a λ/2 wavelength film, a λ/4 wavelength film, and a viewing angle compensation film. Examples of the material of the retardation film include a polymer film which is birefringent by stretching. Examples of the polymer film include a cellulose film and a polyester film. Examples of the cellulose film include cellulose triacetate film. Examples of the polyester film include polyethylene terephthalate film and polyethylene naphthalate film. As the retardation film, a film having a substrate such as a cellulose film and an alignment layer of a liquid crystal compound such as a liquid crystalline polymer on the substrate can be preferably used. The thickness of the functional optical film layer 10 as a retardation film is preferably 0.5 μm or more, more preferably 1 μm or more, from the viewpoint of securing the function and strength of the functional optical film layer 10. The thickness of the functional optical film layer 10 as the retardation film is preferably 5 μm or less, more preferably 3 μm or less, from the viewpoint of thinning the optical laminate X.

The cover film 20 is a release liner in this embodiment. Examples of the material of the cover film 20 include polyester, polyolefin, polyamide, and cellulose. Examples of the polyester include polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate. Examples of the polyolefin include polyethylene, polypropylene, and cycloolefin polymer (COP). Examples of the polyamide include polyamide 6,6 and partially aromatic polyamide. These materials may be used alone or in combination of two or more.

The thickness of the cover film 20 is preferably 50 μm or more, more preferably 75 μm or more, from the viewpoint of securing the surface protection function by the cover film 20.

From the viewpoint of securing the surface protection function by the cover film 20, the Young's modulus E of the cover film 20 at 23℃is preferably 3000MPa or more, more preferably 4000MPa or more, and still more preferably 5000MPa or more. From the viewpoint of securing flexibility of the cover film 20, the young's modulus E of the cover film 20 is preferably 10000MPa or less, more preferably 8000MPa or less, still more preferably 6000MPa or less, particularly preferably 5500MPa or less.

The surface of the cover film 20 on the adhesive layer 40 side is preferably subjected to a peeling treatment. Examples of the stripping treatment include a silicone stripping treatment and a fluorine stripping treatment.

The pixel panel layer 30 is a thin film-like pixel panel in the present embodiment. As the pixel panel, for example, an organic EL panel and a liquid crystal panel are cited. From the viewpoint of ensuring the function of the pixel panel layer 30, the thickness of the pixel panel layer 30 is preferably 10 μm or more, more preferably 15 μm or more. From the viewpoint of thinning the optical laminate X, the thickness of the pixel panel layer 30 is preferably 50 μm or less, more preferably 40 μm or less.

The adhesive layer 40 is a pressure sensitive adhesive layer formed from a first adhesive composition. The adhesive layer 40 has transparency (visible light transmittance). The first adhesive composition contains at least a base polymer.

The base polymer is an adhesive component that causes the adhesive layer 40 to exhibit adhesiveness. Examples of the base polymer include acrylic polymers, silicone polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyvinyl ether polymers, vinyl acetate/vinyl chloride copolymers, modified polyolefin polymers, epoxy polymers, fluoropolymers, and rubber polymers. The base polymer may be used alone or in combination of two or more. From the viewpoint of ensuring good transparency and adhesion of the adhesive layer 40, an acrylic polymer is preferably used as the base polymer.

The acrylic polymer is a copolymer containing a monomer component of an alkyl (meth) acrylate in a proportion of 50 mass% or more. "(meth) acrylic" refers to acrylic and/or methacrylic.

As the alkyl (meth) acrylate, an alkyl (meth) acrylate having an alkyl group with 1 to 20 carbon atoms is suitably used. The alkyl (meth) acrylate may have a linear or branched alkyl group or a cyclic alkyl group such as an alicyclic alkyl group.

Examples of alkyl (meth) acrylates having a linear alkyl group or branched alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (i.e., lauryl (meth) acrylate, isotridecyl (meth) acrylate, tetradecyl (meth) acrylate, isotetradecyl (meth) acrylate, pentadecyl (meth) acrylate, cetyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate), isostearyl (meth) acrylate and nonadecyl (meth) acrylate.

Examples of the alkyl (meth) acrylate having an alicyclic alkyl group include cycloalkyl (meth) acrylate, a (meth) acrylate having a bicyclic aliphatic hydrocarbon ring, and a (meth) acrylate having an aliphatic hydrocarbon ring having three or more rings. Examples of cycloalkyl (meth) acrylates include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate. Examples of the (meth) acrylate having a bicyclic aliphatic hydrocarbon ring include isobornyl (meth) acrylate. Examples of the (meth) acrylic acid ester having an aliphatic hydrocarbon ring having a tricyclic or higher group include dicyclopentyl (meth) acrylate, dicyclopentyloxyethyl (meth) acrylate, tricyclopentyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, and 2-ethyl-2-adamantyl (meth) acrylate.

As the alkyl (meth) acrylate, an alkyl acrylate having an alkyl group having 3 to 15 carbon atoms is preferably used, and at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate and dodecyl acrylate is more preferably used.

The proportion of the alkyl (meth) acrylate in the monomer component is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more, from the viewpoint of appropriately exhibiting basic characteristics such as adhesiveness in the adhesive layer 40. The ratio is, for example, 99 mass% or less.

The monomer component may contain a copolymerizable monomer copolymerizable with the alkyl (meth) acrylate. Examples of the copolymerizable monomer include monomers having a polar group. Examples of the polar group-containing monomer include monomers having a ring containing a nitrogen atom, hydroxyl group-containing monomers, and carboxyl group-containing monomers. The polar group-containing monomer contributes to the introduction of crosslinking points into the acrylic polymer and ensures the modification of the acrylic polymer such as the cohesive force of the acrylic polymer.

Examples of the monomer having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methyl vinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyridine, N-vinylpiperazine, N-vinylpyrzine, N-vinylpyrrolidone, N-vinylimidazole, N-vinyloxazole, N- (meth) acryl-2-pyrrolidone, N- (meth) acryl piperidine, N- (meth) acryl pyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, N-vinyl-3, 5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole and N-vinylisothiazole. As the monomer having a nitrogen atom-containing ring, N-vinyl-2-pyrrolidone is preferably used.

The proportion of the monomer having a ring containing a nitrogen atom in the monomer component is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and still more preferably 0.55 mass% or more, from the viewpoint of securing cohesive force of the adhesive layer 40 and securing adhesion force to an adherend of the adhesive layer 40. From the viewpoints of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (regarding the compatibility of various additive components in the adhesive layer 40 and the acrylic polymer), the ratio is preferably 30 mass% or less, more preferably 20 mass% or less.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate. As hydroxyl group-containing monomers, 4-hydroxybutyl (meth) acrylate is preferably used, and 4-hydroxybutyl acrylate is more preferably used.

The proportion of the hydroxyl group-containing monomer in the monomer component is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and still more preferably 0.8 mass% or more, from the viewpoints of introducing a crosslinked structure into the acrylic polymer and securing cohesive force of the adhesive layer 40. From the viewpoint of adjusting the polarity of the acrylic polymer (regarding the compatibility of various additive components and the acrylic polymer in the adhesive layer 40), the ratio is preferably 20 mass% or less, more preferably 10 mass% or less.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

The proportion of the carboxyl group-containing monomer in the monomer component is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and still more preferably 0.8 mass% or more, from the viewpoints of introducing a crosslinked structure into the acrylic polymer, ensuring cohesive force of the adhesive layer 40, and ensuring adhesion to an adherend of the adhesive layer 40. From the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend by acid, the ratio is preferably 30 mass% or less, more preferably 20 mass% or less.

In order to prevent corrosion of metal elements such as electrodes in the foldable display panel due to acid components, the adhesive layer 40 preferably has a small acid content. In the case where the adhesive layer 40 is used for bonding a polarizing film, the adhesive layer 40 preferably has a small acid content in order to suppress the polyvinyl alcohol polarizer from being multi-olefinated by an acid component. The content of the organic acid monomer (e.g., (meth) acrylic acid and carboxyl group-containing monomer) in the acid-free adhesive layer 40 is preferably 100ppm or less, more preferably 70ppm or less, and still more preferably 50ppm or less. The organic acid monomer content of the adhesive layer 40 was determined as follows: the adhesive layer 40 was immersed in pure water, heated at 100℃for 45 minutes, and the acid monomer extracted into the water by ion chromatography was quantitatively determined.

From the standpoint of acid-free, the base polymer in the adhesive layer 40 preferably contains substantially no organic acid monomer as a monomer component. From the viewpoint of acid-free, the ratio of the organic acid monomer in the monomer component is preferably 0.5 mass% or less, more preferably 0.1 mass% or less, still more preferably 0.05 mass%, and most preferably 0.

The monomer component may comprise other copolymerizable monomers. Examples of the other copolymerizable monomer include an acid anhydride monomer, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, an epoxy group-containing monomer, a cyano group-containing monomer, an alkoxy group-containing monomer, and an aromatic vinyl compound. These other copolymerizable monomers may be used alone or in combination of two or more.

The base polymer has a crosslinked structure in this embodiment. As a method for introducing a crosslinked structure into a base polymer, there can be mentioned: a method of compounding a base polymer having a functional group capable of reacting with a crosslinking agent and a crosslinking agent into a first adhesive composition to react the base polymer and the crosslinking agent in the adhesive layer 40 (first method); and a method (second method) in which a polyfunctional monomer is contained in a monomer component forming a base polymer, and a base polymer having a branched structure (crosslinked structure) introduced into a polymer chain is formed by polymerization of the monomer component. These methods may be used in combination.

Examples of the crosslinking agent used in the first method include compounds that react with functional groups (hydroxyl groups, carboxyl groups, and the like) included in the base polymer. Examples of such a crosslinking agent include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, carbodiimide crosslinking agents, and metal chelate crosslinking agents. The crosslinking agent may be used alone or in combination of two or more. As the crosslinking agent, an isocyanate crosslinking agent, a peroxide crosslinking agent, and an epoxy crosslinking agent are preferably used in view of high reactivity with hydroxyl groups and carboxyl groups in the base polymer and easy introduction of a crosslinked structure.

Examples of the isocyanate crosslinking agent include toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate and polymethylene polyphenyl isocyanate. In addition, as the isocyanate crosslinking agent, derivatives of these isocyanates can be mentioned. Examples of the isocyanate derivative include isocyanurate modified products and polyol modified products. Examples of the commercial products of the isocyanate crosslinking agent include CORONATE L (trimethylolpropane adduct of toluene diisocyanate, manufactured by eastern corporation), CORONATE HL (trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by eastern corporation), CORONATE HX (isocyanurate of hexamethylene diisocyanate, manufactured by eastern corporation), and TAKENATE D N (trimethylolpropane adduct of xylylene diisocyanate, manufactured by mitsunobu chemical corporation).

Examples of the peroxide crosslinking agent include dibenzoyl peroxide, di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, and t-butyl peroxypivalate.

Examples of the epoxy crosslinking agent include bisphenol a, epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol triglycidyl ether, 1, 6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidylamine, N' -tetraglycidyl m-xylylenediamine and 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane.

From the viewpoint of ensuring moderate flexibility (thus bendability) of the adhesive layer 40, isocyanate crosslinking agents (particularly difunctional isocyanate crosslinking agents) and peroxide crosslinking agents are preferable. From the viewpoint of ensuring the durability of the adhesive layer 40, an isocyanate crosslinking agent (particularly, a trifunctional isocyanate crosslinking agent) is preferable. In contrast to the base polymer, which forms softer two-dimensional crosslinks, the difunctional isocyanate crosslinker and the peroxide crosslinker form stronger three-dimensional crosslinks. From the viewpoint of achieving both durability and flexibility of the adhesive layer 40, it is preferable to use a trifunctional isocyanate crosslinking agent in combination with a peroxide crosslinking agent and/or a difunctional isocyanate crosslinking agent.

From the viewpoint of ensuring cohesive force of the adhesive layer 40, the blending amount of the crosslinking agent is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, more preferably 0.07 parts by mass or more, relative to 100 parts by mass of the base polymer. From the viewpoint of ensuring good tackiness in the pressure-sensitive adhesive layer 40, the amount of the crosslinking agent blended with respect to 100 parts by mass of the base polymer is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

In the second method described above, the monomer component (including the polyfunctional monomer for introducing a crosslinked structure and other monomers) may be polymerized at one time or may be polymerized in a plurality of stages. In the multistage polymerization method, first, a monofunctional monomer used for forming a base polymer is polymerized (prepolymerized), thereby producing a prepolymer composition containing a part of a polymer (a mixture of a polymer having a low degree of polymerization and an unreacted monomer). Next, after adding the polyfunctional monomer to the prepolymer composition, a part of the polymer and the polyfunctional monomer are polymerized (main polymerization).

Examples of the polyfunctional monomer include polyfunctional (meth) acrylates having 2 or more ethylenically unsaturated double bonds in 1 molecule. The polyfunctional monomer is preferably a polyfunctional acrylate from the viewpoint of being capable of introducing a crosslinked structure by active energy ray polymerization (photopolymerization).

Examples of the multifunctional (meth) acrylate include difunctional (meth) acrylate, trifunctional (meth) acrylate, and tetrafunctional or higher multifunctional (meth) acrylate.

Examples of the difunctional (meth) acrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 9-nonanediol di (meth) acrylate, glycerol di (meth) acrylate, neopentyl glycol di (meth) acrylate, stearic acid modified pentaerythritol di (meth) acrylate, dicyclopentenyl diacrylate, di (meth) acryl isocyanurate, and alkylene oxide modified bisphenol di (meth) acrylate.

Examples of the trifunctional (meth) acrylate include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and tris (acryloxyethyl) isocyanurate.

Examples of the polyfunctional (meth) acrylate having four or more functions include ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxy penta (meth) acrylate, alkyl-modified dipentaerythritol pentaacrylate, and dipentaerythritol hexa (meth) acrylate.

The acrylic polymer can be formed by polymerizing the above monomer components. Examples of the polymerization method include solution polymerization, bulk polymerization and emulsion polymerization. From the viewpoints of transparency, water resistance, and cost of the adhesive layer 40, solution polymerization is preferable. As the solvent for the solution polymerization, for example, ethyl acetate and toluene are used. As the initiator for polymerization, for example, a thermal polymerization initiator and a photopolymerization initiator are used. The amount of the polymerization initiator is, for example, 0.05 parts by mass or more and 1 part by mass or less based on 100 parts by mass of the monomer component.

Examples of the thermal polymerization initiator include azo polymerization initiators and peroxide polymerization initiators. Examples of the azo polymerization initiator include 2,2' -azobisisobutyronitrile, 2' -azobis-2-methylbutyronitrile, dimethyl 2,2' -azobis (2-methylpropionate), 4' -azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2' -azobis (2-amidinopropane) dihydrochloride, 2' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, 2' -azobis (2-methylpropionamidine) disulfate, and 2,2' -azobis (N, N ' -dimethyleneisobutyl amidine) dihydrochloride. Examples of the peroxide polymerization initiator include dibenzoyl peroxide, t-butyl peroxymaleate, and lauroyl peroxide.

Examples of the photopolymerization initiator include benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α -ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactive oxime photopolymerization initiator, benzoin photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, thioxanthone photopolymerization initiator, and acylphosphine oxide photopolymerization initiator.

In the polymerization, a chain transfer agent and/or a polymerization inhibitor (polymerization retarder) may be used for the purpose of adjusting the molecular weight or the like. Examples of the chain transfer agent include α -thioglycerol, lauryl mercaptan, glycidyl mercaptan, thioglycolic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2, 3-dimercapto-1-propanol, and α -methylstyrene dimer.

The molecular weight of the base polymer can be adjusted by adjusting the kind and/or amount of the polymerization initiator. For example, in radical polymerization, the higher the amount of the polymerization initiator, the higher the radical concentration of the reaction system, and therefore, the density of the reaction initiation point tends to be high and the molecular weight of the base polymer formed tends to be small. In contrast, the smaller the amount of the polymerization initiator, the lower the density of the reaction initiation point, and therefore, the polymer chain tends to be easily elongated, and the molecular weight of the base polymer to be formed tends to be large.

From the viewpoint of ensuring cohesive force of the adhesive layer 40, the weight average molecular weight of the acrylic polymer is preferably 10 ten thousand or more, more preferably 30 ten thousand or more, and still more preferably 50 ten thousand or more. The weight average molecular weight is preferably 500 ten thousand or less, more preferably 300 ten thousand or less, and still more preferably 200 ten thousand or less. The weight average molecular weight of the acrylic polymer was measured by Gel Permeation Chromatography (GPC) and calculated by polystyrene conversion.

The glass transition temperature (Tg) of the base polymer is preferably 0℃or lower, more preferably-10℃or lower, and still more preferably-20℃or lower. The glass transition temperature is, for example, at least-80 ℃.

As the glass transition temperature (Tg) of the base polymer, a glass transition temperature (theoretical value) obtained from the following Fox expression can be used. The Fox formula is a relation between the glass transition temperature Tg of the polymer and the glass transition temperature Tgi of the homopolymer of the monomers constituting the polymer. In the following Fox formula, tg represents the glass transition temperature (. Degree. C.) of the polymer, wi represents the weight fraction of the monomer i constituting the polymer, tgi represents the glass transition temperature (. Degree. C.) of the homopolymer formed from the monomer i. As regards the glass transition temperature of the homopolymer, literature values can be used. For example, glass transition temperatures of various homopolymers are listed in "Polymer Handbook" (4 th edition, john Wiley & Sons, inc., 1999) and "synthetic resin entrance for New Polymer library 7 paint" (North Korea, polymer journal, 1995). On the other hand, the glass transition temperature of the homopolymer of the monomer can be obtained by a method specifically described in JP-A2007-51271.

Fox 1/(273+tg) =Σ [ Wi/(273+tgi) ]

The first adhesive composition may comprise one or two or more oligomers on the basis of the base polymer. In the case of using an acrylic polymer as a base polymer, an acrylic oligomer is preferably used as the oligomer. The acrylic oligomer is a copolymer containing a monomer component of an alkyl (meth) acrylate in an amount of 50 mass% or more, and has a weight average molecular weight of, for example, 1000 to 30000.

The glass transition temperature of the acrylic oligomer is preferably 60℃or higher, more preferably 80℃or higher, still more preferably 100℃or higher, particularly preferably 110℃or higher. The glass transition temperature of the acrylic oligomer is, for example, 200℃or lower, preferably 180℃or lower, and more preferably 160℃or lower. The adhesive force of the adhesive layer 40, particularly at high temperature, is improved by using a combination of a low Tg acrylic polymer (base polymer) having a crosslinked structure introduced therein and a high Tg acrylic oligomer. The glass transition temperature of the acrylic oligomer is calculated using the above Fox equation.

The acrylic oligomer having a glass transition temperature of 60 ℃ or higher is preferably a polymer containing a monomer component of an alkyl (meth) acrylate having a chain alkyl group (a chain alkyl (meth) acrylate) and an alkyl (meth) acrylate having an alicyclic alkyl group (an alicyclic alkyl (meth) acrylate). Specific examples of these alkyl (meth) acrylates include, for example, the alkyl (meth) acrylates described above as monomer components of the acrylic polymer.

The chain alkyl (meth) acrylate is preferably methyl methacrylate because of its high glass transition temperature and excellent compatibility with the base polymer. The alicyclic alkyl (meth) acrylate is preferably dicyclopentyl acrylate, dicyclopentyl methacrylate, cyclohexyl acrylate or cyclohexyl methacrylate. That is, the acrylic oligomer is preferably a polymer containing 1 or more monomer components selected from the group consisting of dicyclopentyl acrylate, dicyclopentyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate and methyl methacrylate.

The proportion of the alicyclic alkyl (meth) acrylate in the monomer component of the acrylic oligomer is preferably 10% by weight or more, more preferably 20% by weight or more, and still more preferably 30% by weight or more. The proportion is preferably 90% by weight or less, more preferably 80% by weight or less, and still more preferably 70% by weight or less. The proportion of the chain alkyl (meth) acrylate in the monomer component of the acrylic oligomer is preferably 90% by weight or less, more preferably 80% by weight or less, and still more preferably 70% by weight or less. The proportion is preferably 10% by weight or more, more preferably 20% by weight or more, and still more preferably 30% by weight or more.

The weight average molecular weight of the acrylic oligomer is preferably 1000 or more, more preferably 1500 or more, and still more preferably 2000 or more. The molecular weight is preferably 30000 or less, more preferably 10000 or less, and further preferably 8000 or less. The molecular weight range of such an acrylic oligomer is preferable for securing the adhesive force and the adhesive holding force of the adhesive layer 40.

The acrylic oligomer can be obtained by polymerizing the monomer components of the acrylic oligomer. Examples of the polymerization method include solution polymerization, active energy ray polymerization (for example, UV polymerization), bulk polymerization, and emulsion polymerization. In the polymerization of the acrylic oligomer, a polymerization initiator may be used, or a chain transfer agent may be used for the purpose of adjusting the molecular weight.

In order to sufficiently improve the adhesive force of the adhesive layer 40, the content of the acrylic oligomer in the adhesive layer 40 is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and still more preferably 1 part by mass or more relative to 100 parts by mass of the base polymer. On the other hand, from the viewpoint of ensuring the transparency of the adhesive layer 40, the content of the acrylic oligomer in the adhesive layer 40 is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and still more preferably 3 parts by mass or less relative to 100 parts by mass of the base polymer. When the content of the acrylic oligomer in the pressure-sensitive adhesive layer 40 is too large, the compatibility of the acrylic oligomer decreases, and haze tends to increase and transparency tends to decrease.

The first adhesive composition may contain a silane coupling agent. The content of the silane coupling agent in the first adhesive composition is preferably 0.1 part by mass or more, more preferably 0.2 part by mass or more, relative to 100 parts by mass of the base polymer. The content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less.

The first adhesive composition may contain other components as needed. Examples of the other components include tackifiers, plasticizers, softeners, anti-deterioration agents, fillers, colorants, ultraviolet absorbers, antioxidants, surfactants, and antistatic agents.

The haze of the adhesive layer 40 is preferably 3% or less, more preferably 2% or less, and still more preferably 1% or less. The haze of the adhesive layer 40 can be measured in accordance with JIS K7136 (year 2000) using a haze meter. Examples of the haze meter include "NDH2000" manufactured by Nippon electric color industry Co., ltd. And "HM-150" manufactured by Country color technology research Co., ltd.

The total light transmittance of the adhesive layer 40 is preferably 60% or more, more preferably 80% or more, and still more preferably 85% or more. The total light transmittance of the adhesive layer 40 is, for example, 100% or less. The total light transmittance of the adhesive layer 40 can be measured in accordance with JIS K7375 (2008).

The adhesive layer 50 is a pressure sensitive adhesive layer formed of a second adhesive composition. The adhesive layer 50 has transparency. The second adhesive composition contains at least a base polymer. The base polymer contained in the second adhesive composition includes, for example, the base polymer described above for the first adhesive composition. The base polymer in the first adhesive composition may be the same as or different from the base polymer in the second adhesive composition. The second adhesive composition may contain ingredients other than the base polymer. Examples of the component contained in the second adhesive composition include components other than the base polymer described above for the first adhesive composition. The composition of the first adhesive composition may be the same as or different from the composition of the second adhesive composition.

The haze of the adhesive layer 50 is preferably 3% or less, more preferably 2% or less, and still more preferably 1% or less. The haze of the adhesive layer 50 can be measured according to JIS K7136 (year 2000) using a haze meter.

The total light transmittance of the adhesive layer 50 is preferably 60% or more, more preferably 80% or more, and still more preferably 85% or more. The total light transmittance of the adhesive layer 50 is, for example, 100% or less. The total light transmittance of the adhesive layer 50 can be measured in accordance with JIS K7375 (2008).

The optical laminate X can be manufactured, for example, as follows.

First, the functional optical film layer 10, the pressure-sensitive adhesive layer 40 with the cover film 20, the pressure-sensitive adhesive layer 50 with a release liner, and the pixel panel layer 30 (film-like pixel panel) are prepared (preparation step).

The adhesive layer 40 with the cover film 20 may be formed by coating a first adhesive composition (varnish) on the cover film 20 to form a coating film, and then drying the coating film. Examples of the coating method of the first adhesive composition include roll coating, roll lick 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 (the same applies to the coating method described below for other adhesive compositions). An additional release liner may be further laminated on the adhesive layer 40 on the cover film 20. The release liner is released prior to the attachment of the functional optical film layer 10 to the adhesive layer 40.

The release liner-attached adhesive layer 50 may be formed by coating a second adhesive composition (varnish) on a release liner to form a coating film, and then drying the coating film. An additional release liner may be further laminated on the adhesive layer 50 on the release liner. The release liner is released prior to the attachment of the functional optical film layer 10 to the adhesive layer 50.

Next, the first surface 11 of the functional optical film layer 10 is bonded to the pressure-sensitive adhesive layer 40 side of the pressure-sensitive adhesive layer 40 with the cover film 20 (first bonding step). Next, the second surface 12 of the functional optical film layer 10 is bonded to the pressure-sensitive adhesive layer 50 side of the release liner-attached pressure-sensitive adhesive layer 50 (second bonding step). Preferably, it is: prior to their attachment, the first and second faces 11, 12 of the functional optical film layer 10, the exposed face of the adhesive layer 40 with the cover film 20, and the exposed face of the adhesive layer 50 with the release liner are subjected to a plasma treatment.

By the first bonding step and the second bonding step, a covered optical film Y is obtained as shown in a of fig. 3. The coated optical film Y includes, in order along the thickness direction D, a coating film 20, an adhesive layer 40, a functional optical film layer 10, and an adhesive layer 50.

Next, as shown in fig. 3B, the covered optical film Y is bonded to the pixel panel layer 30. Specifically, the pressure-sensitive adhesive layer 50 side of the covered optical film Y is bonded to one surface of the pixel panel layer 30 in the thickness direction. Before this bonding, the exposed surface of the adhesive layer 50 and one surface in the thickness direction of the pixel panel layer 30 are preferably subjected to plasma treatment.

In this way, the optical laminate X can be manufactured. As described above, the optical laminate X is suitable for performing the contour processing of the portion from the pixel panel layer 30 to the adhesive layer 40 without cutting the cover film 20 by irradiating the laser beam R to the pixel panel layer 30 side in the thickness direction D. Laser cutting is preferable as a profile processing method because it can process a profile with high precision. The optical laminate X after the contour processing is supplied to a production line of flexible display panels. The cover film 20 is peeled off from the adhesive layer 40 at a predetermined timing.

Examples of the laser beam for laser processing include a gas laser beam, a solid-state laser beam, and a semiconductor laser beam. Examples of the gas laser include excimer laser and CO ₂ Laser (10.6 μm) (the numbers in brackets indicate the laser wavelength. With respect to laser, the same applies hereinafter). Examples of the excimer laser include F ₂ Excimer laser (157 nm), arF excimer laser (193 nm), krF excimer laser (248 nm), and XeCl excimer laser (308 nm). Examples of the solid-state laser include a Nd/YAG laser (1064 nm), a second harmonic of the Nd/YAG laser (532 nm), a third harmonic of the Nd/YAG laser (355 nm), and a fourth harmonic of the Nd/YAG laser (266 nm). As the semiconductor laser, for example, a semiconductor laser having a wavelength of 405nm is cited. In laser processing, the pulse width of the irradiated laser is, for example, 0.5 to 50 μsec, the frequency of the pulse is, for example, 1 to 200kHz, and the laser output is, for example, 2 to 250W.

Examples

The present invention will be specifically described with reference to the following examples. The present invention is not limited to the examples. The specific numerical values of the compounding amounts (contents), physical property values, parameters and the like described below may be replaced with the upper limits (numerical values defined in the form of "below" or "less") or the lower limits (numerical values defined in the form of "above" or "exceeding") of the compounding amounts (contents), physical property values, parameters and the like described in the above-described "specific embodiments" corresponding thereto.

Preparation of acrylic base Polymer

In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube, a mixture comprising 64 parts by mass of 2-ethylhexyl acrylate (2 EHA), 30 parts by mass of N-Butyl Acrylate (BA), 4 parts by mass of Lauryl Acrylate (LA), 1 part by mass of 4-hydroxybutyl acrylate (4 HBA), 1 part by mass of N-vinyl-2-pyrrolidone (NVP), 0.3 part by mass of 2,2' -Azobisisobutyronitrile (AIBN) as a thermal polymerization initiator and ethyl acetate as a solvent was stirred at 56 ℃ under a nitrogen atmosphere for 6 hours (polymerization reaction). Thus, a polymer solution containing an acrylic base polymer was obtained. The weight average molecular weight of the acrylic base polymer in the polymer solution was about 200 ten thousand.

Preparation of acrylic oligomers

A mixture containing 95 parts by mass of cyclohexyl methacrylate (CHMA), 5 parts by mass of Acrylic Acid (AA), 10 parts by mass of an alpha-methylstyrene dimer as a chain transfer agent, and toluene as a solvent was stirred at room temperature under a nitrogen atmosphere for 1 hour in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube. Thereafter, 10 parts by mass of 2,2' -Azobisisobutyronitrile (AIBN) as a thermal polymerization initiator was added to the mixture to prepare a reaction solution, which was reacted at 85 ℃ for 5 hours under a nitrogen atmosphere (formation of an acrylic oligomer). Thus, an oligomer solution (solid content concentration: 50 mass%) containing the acrylic oligomer was obtained. The weight average molecular weight of the acrylic oligomer was 4000. In addition, the glass transition temperature (Tg) of the acrylic oligomer was 84 ℃.

Preparation of adhesive composition

To the polymer solution, 1.5 parts by mass of an acrylic oligomer, 0.26 parts by mass of a first crosslinking agent (product name "NIPER BMT-40SV", dibenzoyl peroxide, manufactured by Japanese fat and oil Co., ltd.), 0.02 parts by mass of a second crosslinking agent (product name "CORONATE L", trimethylolpropane adduct of toluene diisocyanate, manufactured by Tosoh Co., ltd.), and 0.3 parts by mass of a silane coupling agent (product name "KBM-403", manufactured by Xinyue chemical Co., ltd.) were added and mixed with respect to 100 parts by mass of the acrylic base polymer in the polymer solution to prepare an adhesive composition.

Production of adhesive sheet

The release liner L1 having one surface subjected to silicone release treatment is coated with the adhesive composition on the release treated surface to form a coating film. The release liner L1 was a polyethylene terephthalate (PET) film (product name "DIAFOIL MRV50", thickness 50 μm, manufactured by Mitsubishi chemical corporation) having one side subjected to silicone release treatment. Next, a release-treated surface of the release liner L2, which has been subjected to a silicone release treatment on one side, is bonded to the coating film on the release liner L1. The release liner L2 was a PET film (product name "DIAFOIL MRV50", thickness 50 μm, manufactured by Mitsubishi chemical Co., ltd.) having one side subjected to silicone release treatment. Then, the coating film sandwiched between the release liner L1 and the release liner L2 was dried by heating at 100 ℃ for 1 minute and then heating at 150 ℃ for 3 minutes, to form an adhesive sheet having a thickness of 50 μm and formed of a transparent adhesive layer. In the above manner, adhesive sheets (release liner L1/adhesive layer (thickness 50 μm)/release liner L2) with release liners L1, L2 were produced.

The release liner L3 was used instead of the release liner L1, and adhesive sheets with release liners L3 and L2 (release liner L3/adhesive layer (thickness 50 μm)/release liner L2) were produced in the same manner as the adhesive sheets with release liners L1 and L2. The release liner L3 was a PET film (product name "DIAFOIL MRV75", thickness 75 μm, manufactured by Mitsubishi chemical Co., ltd.) having one side subjected to silicone release treatment.

The release liner L4 was used instead of the release liner L1, and adhesive sheets with release liners L4 and L2 (release liner L4/adhesive layer (thickness 50 μm)/release liner L2) were produced in the same manner as the adhesive sheets with release liners L1 and L2. The release liner L4 was a PET film (product name "DIAFOIL MRV100", thickness 100 μm, manufactured by Mitsubishi chemical Co., ltd.) having one side subjected to silicone release treatment.

The release liner L5 was used instead of the release liner L1, and adhesive sheets with release liners L5 and L2 (release liner L5/adhesive layer (thickness 50 μm)/release liner L2) were produced in the same manner as the adhesive sheets with release liners L1 and L2. The release liner L5 was a PET film (product name "DIAFOIL MRV125", thickness 125 μm, manufactured by Mitsubishi chemical Co., ltd.) having one side subjected to silicone release treatment.

[ example 1 ]

First, the release liner L2 is peeled from the adhesive sheet (first adhesive sheet) with the release liners L1, L2. Then, the exposed surface of the first adhesive sheet exposed by the peeling is subjected to plasma treatment. On the other hand, both sides (first side, second side) of the first polarizing film having a thickness of 31 μm were also subjected to plasma treatment. In each plasma treatment, a plasma irradiation apparatus (trade name "AP-TO5", manufactured by water industry Co., ltd.) was used, the voltage was set TO 160V, the frequency was set TO 10kHz, and the treatment speed was set TO 5000 mm/min (the same applies TO the plasma treatment described later). And bonding the exposed surface of the first adhesive sheet to the first surface of the first polarizing film. In this bonding, the pressure-sensitive adhesive sheet was pressure-bonded to the first polarizing film by a single operation of moving a 2kg roller back and forth at 25 ℃.

Next, the release liner L2 is peeled off from the other adhesive sheet (second adhesive sheet) with release liners L1, L2. Then, the exposed surface of the second pressure-sensitive adhesive sheet exposed by the peeling is subjected to plasma treatment. And bonding the exposed surface of the second adhesive sheet to the second surface of the first polarizing film.

Then, the release liner L1 is peeled off from the second adhesive sheet on the first polarizing film. Then, the exposed surface of the second pressure-sensitive adhesive sheet exposed by the peeling is subjected to plasma treatment. On the other hand, a Polyimide (PI) film (product name "UPILEX", manufactured by the company of yu, inc.) having a thickness of 50 μm was also subjected to plasma treatment. And bonding the exposed surface of the second adhesive sheet on the first polarizing film to the plasma-treated surface of the PI film.

In the above manner, the optical laminate of example 1 was produced. The optical laminate includes, in order in the thickness direction, a release liner L1 (thickness 50 μm) as a cover film, a first adhesive layer (thickness 50 μm), a first polarizing film (thickness 31 μm) as an optical film, a second adhesive layer (thickness 50 μm), and a PI film (thickness 50 μm). The PI film is an element imitating the pixel panel layer. The first pressure-sensitive adhesive layer, the first polarizing film, and the second pressure-sensitive adhesive layer form a polarizing film having pressure-sensitive adhesive layers on both sides (the same applies to examples 2 to 5 described below).

[ example 2 ]

An optical laminate of example 2 was produced in the same manner as the optical laminate of example 1, except that the first adhesive sheet with release liners L1 and L2 was replaced with the adhesive sheet with release liners L3 and L2. The optical laminate of example 2 had the same laminate structure as the optical laminate of example 1 except that the release liner L3 (thickness 75 μm) was provided as a cover film.

[ example 3 ]

An optical laminate of example 3 was produced in the same manner as the optical laminate of example 1, except that the second polarizing film having a thickness of 100 μm was used instead of the first polarizing film. The optical laminate of example 3 had the same laminate structure as the optical laminate of example 1 except that the second polarizing film (thickness 100 μm) was provided instead of the first polarizing film.

[ example 4 ]

An optical laminate of example 4 was produced in the same manner as the optical laminate of example 1, except that the first adhesive sheet with release liners L1 and L2 was replaced with the adhesive sheet with release liners L4 and L2. The optical laminate of example 4 had the same laminate structure as the optical laminate of example 1 except that the release liner L4 (thickness 100 μm) was provided as a cover film.

[ example 5 ]

An optical laminate of example 5 was produced in the same manner as the optical laminate of example 1, except that the first adhesive sheet with release liners L5 and L2 was replaced with the adhesive sheet with release liners L1 and L2. The optical laminate of example 5 had the same laminate structure as the optical laminate of example 1 except that the release liner L5 (thickness 125 μm) was provided as a cover film.

[ example 6 ]

An optical laminate of example 6 was produced in the same manner as the optical laminate of example 1, except that the first base film (product name "RV-20UB", acrylic film, thickness 20 μm, manufactured by eastern steel sheet company) was used instead of the first polarizing film. The optical laminate of example 6 was provided with a release liner L1 (thickness 50 μm), a first adhesive layer (thickness 50 μm), a first base film (thickness 20 μm), a second adhesive layer (thickness 50 μm) and a PI film (thickness 50 μm) as cover films, in this order, in the thickness direction. The first adhesive layer, the first substrate film, and the second adhesive layer form a double-sided adhesive sheet having a core substrate (the same applies to examples 7 to 13 and comparative example 1 described later).

Example 7

An optical laminate of example 7 was produced in the same manner as the optical laminate of example 1, except for the following matters. The first adhesive sheet with release liners L1, L2 is replaced with the adhesive sheet with release liners L4, L2. Instead of the first polarizing film, a first base film (trade name "RV-20UB", acrylic film, thickness 20 μm, manufactured by Toyo Steel plate Co., ltd.) was used.

The optical laminate of example 7 was provided with a release liner L4 (thickness 100 μm), a first adhesive layer (thickness 50 μm), an acrylic film (thickness 20 μm), a second adhesive layer (thickness 50 μm) and a PI film (thickness 50 μm) as cover films in this order in the thickness direction.

Example 8

An optical laminate of example 8 was produced in the same manner as the optical laminate of example 1, except that a second base film (product name "HX-40UF", acrylic film, thickness 40 μm, manufactured by Toyo Steel plate Co., ltd.) was used instead of the first polarizing film. The optical laminate of example 8 has the same laminate structure as the optical laminate of example 1, except that an acrylic film (thickness 40 μm) was provided as the optical film instead of the first polarizing film.

[ example 9 ]

An optical laminate of example 9 was produced in the same manner as the optical laminate of example 1, except for the following matters. The first adhesive sheet with release liners L1, L2 is replaced with the adhesive sheet with release liners L4, L2. A second base film (product name "HX-40UF", acrylic film, thickness 40 μm, manufactured by Toyo Steel plate Co., ltd.) was used instead of the first polarizing film.

The optical laminate of example 9 was provided with a release liner L4 (thickness 100 μm), a first adhesive layer (thickness 50 μm), an acrylic film (thickness 40 μm), a second adhesive layer (thickness 50 μm) and a PI film (thickness 50 μm) as a cover film in this order in the thickness direction.

[ example 10 ]

An optical laminate of example 10 was produced in the same manner as the optical laminate of example 1, except that a third base film (trade name "Lumirror s10#38", PET film, thickness 38 μm, manufactured by ori corporation) was used instead of the first polarizing film. The optical laminate of example 8 had the same laminate structure as the optical laminate of example 1 except that a PET film (thickness 38 μm) was provided as the optical film instead of the first polarizing film.

[ example 11 ]

An optical laminate of example 11 was produced in the same manner as the optical laminate of example 1, except for the following matters. The first adhesive sheet with release liners L1, L2 is replaced with the adhesive sheet with release liners L4, L2. A third base film (trade name "Lumirror s10#38", PET film, thickness 38 μm, manufactured by ori corporation) was used instead of the first polarizing film.

The optical laminate of example 11 was provided with a release liner L4 (thickness 100 μm), a first adhesive layer (thickness 50 μm), a PET film (thickness 38 μm), a second adhesive layer (thickness 50 μm) and a PI film (thickness 50 μm) as a cover film in this order in the thickness direction.

[ example 12 ]

An optical laminate of example 12 was produced in the same manner as the optical laminate of example 1, except for the following matters. The first adhesive sheet with release liners L1, L2 is replaced with the adhesive sheet with release liners L3, L2. A fourth base film (trade name "Lumirror s10#50", PET film, thickness 50 μm, manufactured by ori corporation) was used instead of the first polarizing film.

The optical laminate of example 12 was provided with a release liner L3 (thickness 75 μm), a first adhesive layer (thickness 50 μm), a PET film (thickness 50 μm), a second adhesive layer (thickness 50 μm) and a PI film (thickness 50 μm) as a cover film in this order in the thickness direction.

[ example 13 ]

An optical laminate of example 13 was produced in the same manner as the optical laminate of example 1, except for the following matters. The first adhesive sheet with release liners L1, L2 is replaced with the adhesive sheet with release liners L4, L2. A fourth base film (trade name "Lumirror s10#50", PET film, thickness 50 μm, manufactured by ori corporation) was used instead of the first polarizing film.

The optical laminate of example 13 was provided with a release liner L4 (thickness 100 μm), a first adhesive layer (thickness 50 μm), a PET film (thickness 50 μm), a second adhesive layer (thickness 50 μm) and a PI film (thickness 50 μm) as a cover film in this order in the thickness direction.

Comparative example 1

An optical laminate of comparative example 1 was produced in the same manner as the optical laminate of example 1, except that a fifth base film (product name "Lumirror s10#75", PET film, thickness 75 μm, manufactured by ori corporation) was used instead of the first polarizing film. The optical laminate of comparative example 1 had the same laminate structure as the optical laminate of example 1 except that a PET film (thickness 75 μm) was provided as the optical film instead of the first polarizing film.

Light transmittance

The films and the adhesive layers used in examples 1 to 13 and comparative example 1 were each measured for light transmittance T at 355nm using a spectrophotometer (product name "U-4100", manufactured by Hitachi Ltd.). The measurement temperature was set at 23 ℃. In the measurement of the transmittance of the pressure-sensitive adhesive layer, a measurement sample obtained by bonding the pressure-sensitive adhesive layer to the glass plate was used, and the transmittance obtained by measuring only the glass plate under the same conditions was used as a base line. The measurement results are shown in 1 to 3.

Young's modulus

Young's modulus at 23℃was examined for each of the films and each of the adhesive layers used in examples 1 to 13 and comparative example 1. Specifically, the following is shown.

First, a test piece (width 10 mm. Times. Predetermined length) was cut out from a measurement object (film, adhesive layer). Next, a tensile test was performed on the test piece at 23℃and a relative humidity of 50% using a tensile tester (product name "Autograph AGS-J", manufactured by Shimadzu corporation), and tensile stress generated during the tensile process was measured. In the tensile test, the initial distance between chucks was set to 10mm, and the tensile speed was set to 200 mm/min. And, according to the tensile deformation (. Epsilon.) ₁ ) Tensile stress σ at 0.05% (=0.0005) ₁ And the tensile deformation (. Epsilon.) ₂ ) Tensile stress σ at 0.25% (=0.0025) ₂ Young's modulus E was obtained from the following equation. Tables 1 to 3 show the Young's modulus E (MPa) obtained.

E＝(σ ₂ -σ ₁ )/(ε ₂ -ε ₁ )

Tables 1 to 3 show the product (e×t) of young's modulus E (MPa) and light transmittance T (%) and the product (e×t×h) of young's modulus E (MPa) and light transmittance T (%) and thickness H (μm) for each film and each adhesive layer. The product P of Young's modulus E (MPa) and transmittance T (%) and thickness H (μm) of the cover film is obtained ₁ (E.times.T.times.H) and the total S of E.times.T.times.H of each layer except the cover film ₁ The differences are also shown in tables 1 to 3. Young's modulus E (MPa) of the cover film and the penetrationProduct P of light ratio T (%) ₂ (E×T) total S of E×T of layers other than the cover film ₂ The differences are also shown in tables 1 to 3.

Laser machining

The optical laminates of examples 1 to 13 and comparative example 1 were examined for laser processability in which the cover film was left and the portions other than the cover film were cut. Specifically, the following is shown.

First, a cutting process of irradiating a PI film side of an optical laminate with laser light from the laminate in the thickness direction and scanning a laser irradiation portion along a line to cut is tried a plurality of times by a picosecond laser processing apparatus according to laser output power. The laser processing apparatus was equipped with an oscillator manufactured by COHERENT corporation, and the maximum laser output was 4W. In each process, picosecond laser light having a wavelength of 355nm was used, the laser frequency was set to 50kHz, the pulse width was set to 0.2 μm, and the laser attenuator (attenuator) of the apparatus was set to a predetermined output, whereby the laser output power was adjusted to a predetermined value, the scanning speed was set to 10 mm/sec, and the number of times of scanning by laser irradiation along the line to be cut was set to 3. In the initial test among the plurality of tests of the dicing process, the Laser Attenuator (LA) output was set to 100%, and the LA output was successively reduced for each test, and the test was repeated until the predetermined LA output was cut from the PI film in the optical laminate to the first adhesive layer. Tables 1 to 3 show the maximum LA output (%) that can be cut from the PI film to the first adhesive layer in the optical laminate. The ratio of the laser output power at the maximum LA output power to the maximum laser output power (4W) was set as the dicing laser output power (%) and is shown in tables 1 to 3. The smaller the cutting laser output power, the easier it is to cut the portions other than the cover film while leaving the cover film. In the optical layered bodies of examples 1 to 13, the product P of the cover films ₁ (E x T x H) is greater than the total S of E x T x H of the layers except the cover film ₁ . Therefore, in the optical layered bodies of examples 1 to 13, the dicing laser output power was as low as 70% or less. In the optical layered bodies of examples 1 to 9, the product of the cover filmsP ₂ (E×T) is greater than the total S of E×T of the layers except the cover film ₂ . Therefore, in the optical layered bodies of examples 1 to 9, the dicing laser output power was further reduced to 50% or less.

TABLE 1

TABLE 2

TABLE 3

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Claims

1. An optical laminate comprising, in order in the thickness direction, a cover film, a first adhesive layer, a functional optical film layer, a second adhesive layer, and a pixel panel layer,

the cover film has a product P of Young's modulus (MPa) at 23 ℃ and light transmittance (%) at 355nm wavelength and thickness (μm) ₁ Is greater than the sum S of the Young' S modulus (MPa) at 23 ℃ and the product of the light transmittance (%) at 355nm wavelength and the thickness (mum) of each layer ₁ 。

2. The optical stack according to claim 1, wherein the product P ₁ Is 0.5X10 ⁷ The above.

3. The optical stack according to claim 1, wherein the product P ₁ And sum S with ₁ The difference is 1X 10 ⁷ The above.

4. The optical laminate according to claim 1, wherein the cover film has a young's modulus (MPa) at 23 ℃ ) Product P of light transmittance (%) at wavelength 355nm ₂ Is greater than the sum S of the product of Young' S modulus (MPa) at 23 ℃ and light transmittance (%) at 355nm wavelength of each layer ₂ 。

5. The optical stack according to claim 4, wherein the product P ₂ Is 1X 10 ⁵ The above.

6. The optical stack according to claim 4, wherein the product P ₂ And sum S with ₂ The difference is 1X 10 ⁵ The above.

7. The optical laminate according to any one of claims 1 to 6, wherein the functional optical film is a polarizing film.

8. A coated optical film for use in the optical laminate of claim 1 to 7,

the coated optical film includes, in order in a thickness direction, the coating film, the first adhesive layer, the functional optical film layer, and the second adhesive layer.