TWI883213B - Polarizing film with adhesive layer, image display panel, method for manufacturing image display panel, and adhesive layer - Google Patents

Abstract

The present invention provides a polarizing film with an adhesive layer, wherein the adhesive layer can maintain the reworkability after preheating even when attached to a conductive layer, and has durability in a high temperature environment. The polarizing film with an adhesive layer of the present invention has a polarizing film and an adhesive layer formed by an adhesive composition. The adhesive composition contains a compound (C) having an acid group or anhydride group and a polyether compound (D). For the adhesive layer, the adhesion P ₈₅ is less than 10.0N/25mm, and the adhesion P ₁₀₅ is greater than 10.0N/25mm.

Description

Polarizing film with adhesive layer, image display panel, method for manufacturing image display panel, and adhesive layer Invention Field

The present invention relates to a polarizing film with an adhesive layer, an image display panel, a method for manufacturing an image display panel, and an adhesive layer.

Background technology

The image display panel of an image display device such as a liquid crystal display device has a structure in which a polarizing film is attached to a transparent substrate through an adhesive layer. On the surface of the transparent substrate, in order to prevent the image display device from being charged, a conductive layer containing metal oxides such as indium tin oxide (ITO) is sometimes provided. When a conductive layer is provided on the surface of the transparent substrate, in the image display panel, the adhesive layer is usually directly connected to the conductive layer.

When manufacturing an image display panel, for example, a polarizing film with an adhesive layer that already has an adhesive layer and a polarizing film is attached to a transparent substrate. At this time, there may be a problem that the attachment position of the polarizing film with an adhesive layer deviates or foreign matter is mixed between the polarizing film with an adhesive layer and the transparent substrate. In this case, in order to improve the productivity of the image display panel, it is advisable to peel the polarizing film with an adhesive layer from the transparent substrate and reuse the component. Therefore, the polarizing film with an adhesive layer is required to be easily peeled off from the transparent substrate. In this manual, the ease of peeling off the polarizing film with adhesive layer from the transparent substrate or conductive layer is sometimes expressed as "the workability of the adhesive layer".

Prior art literature Patent Literature

Patent document 1: Japanese Patent No. 6071459

Summary of invention

When the moisture content of the polarizing film is high, if the image display device is used in a high temperature environment (for example, an environment with a temperature higher than 95°C), the optical properties of the image display device tend to decrease (for example, Patent Document 1). When the polarizer in the polarizing film contains polyvinyl alcohol, the decrease in optical properties in a high temperature environment will be particularly obvious. Therefore, when it is envisioned to use the image display device in a high temperature environment, for example, when the image display device is used as a vehicle-mounted display, the polarizing film with an adhesive layer must be heated (preheated) at a temperature of about 70°C to 95°C at the stage where the polarizing film with an adhesive layer is attached to the transparent substrate to reduce the moisture content of the polarizing film in advance.

However, the polarizing film or the transparent substrate may be damaged by the preheating. Therefore, it is required that the adhesive layer can maintain its reproducibility even after preheating, and the polarizing film with the adhesive layer attached can be peeled off from the transparent substrate. However, the adhesive layer in the polarizing film with the adhesive layer attached usually adjusts its composition to improve the adhesion in a high temperature environment. Therefore, when the above-mentioned preheating is performed, there is a tendency that the adhesion of the adhesive layer is improved and the reproducibility of the adhesive layer is reduced. According to the research of the inventors, when the adhesive layer is directly connected to the conductive layer, especially the ITO layer, the reproducibility is significantly reduced.

According to the research of the inventors, if an excessive amount of a compound that can enhance the reusability of the adhesive layer is added to the adhesive layer, it may be possible to suppress the decrease in the reusability of the adhesive layer caused by preheating. However, in this case, there is a tendency for the durability of the adhesive layer to be greatly reduced in a high temperature environment.

Therefore, the purpose of the present invention is to provide a polarizing film with an adhesive layer, the adhesive layer of which can maintain the reworkability after preheating even when attached to the conductive layer, and has durability in a high temperature environment.

The present invention provides a polarizing film with an adhesive layer, which comprises a polarizing film and an adhesive layer formed by an adhesive composition, wherein the adhesive composition contains a compound (C) having an acid group or anhydride group and a polyether compound (D), and the adhesive layer has an adhesive force P ₈₅ obtained by the following test 1 of less than 10.0 N/25 mm, and an adhesive force P ₁₀₅ obtained by the following test 2 of greater than 10.0 N/25 mm.

Test 1: The adhesive layer on the indium tin layer attached to the indium tin layer was heat treated at 85°C for 5 hours. The force required to peel the adhesive layer from the indium tin layer at a peeling speed of 300 mm/min and a peeling angle of 90° was measured (bonding force P ₈₅ ).

Test 2: The adhesive layer on the indium tin layer attached to the indium tin layer was heat treated at 105°C for 24 hours. The force required to peel the adhesive layer from the indium tin layer at a peeling speed of 300 mm/min and a peeling angle of 90° was measured (bonding force P ₁₀₅ ).

Furthermore, the present invention provides an image display panel, which comprises: the polarizing film with the above-mentioned adhesive layer; a conductive layer containing a metal oxide; and a transparent substrate; the above-mentioned adhesive layer is directly connected to the above-mentioned conductive layer.

Furthermore, the present invention provides a method for manufacturing an image display panel, which is a method for manufacturing the above-mentioned image display panel, comprising: after the polarizing film with the above-mentioned adhesive layer is attached to the above-mentioned conductive layer, the above-mentioned adhesive layer is subjected to a first heating treatment at 70°C to 95°C.

Furthermore, the present invention provides an adhesive layer, which is formed by an adhesive composition, and the aforementioned adhesive composition contains a compound (C) having an acid group or anhydride group and a polyether compound (D), and the adhesion force _P85 obtained by the following test 1 is less than 10.0N/25mm, and the adhesion force _P105 obtained by the following test 2 is greater than 10.0N/25mm.

Test 1: The adhesive layer on the indium tin layer attached to the indium tin layer was heat treated at 85°C for 5 hours. The force required to peel the adhesive layer from the indium tin layer at a peeling speed of 300 mm/min and a peeling angle of 90° was measured (bonding force P ₈₅ ).

Test 2: The adhesive layer on the indium tin layer attached to the indium tin layer was heat treated at 105°C for 24 hours. The force required to peel the adhesive layer from the indium tin layer at a peeling speed of 300 mm/min and a peeling angle of 90° was measured (bonding force P ₁₀₅ ).

According to the present invention, a polarizing film with an adhesive layer can be provided, wherein the adhesive layer can maintain the reworkability after preheating even when attached to the conductive layer, and has durability in a high temperature environment.

1,1a,1b: Adhesive layer

2,2a,2b: Polarizing film

3: Conductive layer

4,6:Transparent substrate

5: Liquid crystal layer

10,10a,10b: Polarizing film with adhesive layer

11: Layer 1

12: Layer 2

13: Layer 3

20: Liquid crystal unit

100,110: Image display panel

Figure 1 is a cross-sectional view of a polarizing film with an adhesive layer in one embodiment of the present invention.

Figure 2 is a diagram used to illustrate the characteristics of the adhesive layer contained in the polarizing film with an adhesive layer.

Figure 3 is a cross-sectional view of an image display panel in an embodiment of the present invention.

FIG4 is a cross-sectional view of a variation of an image display panel.

The form used to implement the invention

The following describes the details of the present invention, but the following description is not intended to limit the present invention to a specific implementation form.

(Implementation form of polarizing film with adhesive layer)

As shown in FIG. 1 , the polarizing film 10 with an adhesive layer of the present embodiment includes an adhesive layer 1 and a polarizing film 2. The adhesive layer 1 is, for example, directly in contact with the polarizing film 2. The surface of the adhesive layer 1 is, for example, exposed to the outside of the polarizing film 10 with an adhesive layer.

In the polarizing film 10 with an adhesive layer, for the adhesive layer 1, the adhesive force P ₈₅ obtained by test 1 is less than 10.0 N/25 mm, and the adhesive force P ₁₀₅ obtained by test 2 is greater than 10.0 N/25 mm.

Test 1 was conducted using the following method. First, the polarizing film 10 with an adhesive layer was cut into a thin rectangular shape of 150 mm in length and 25 mm in width to prepare a test piece. Next, a glass with an indium tin oxide (ITO) layer was prepared. The glass with the ITO layer, for example, has alkali-free glass and an ITO layer in contact with the alkali-free glass. Alkali-free glass is glass that does not substantially contain alkaline components (alkaline metal oxides). Specifically, the weight ratio of alkaline components in the glass is, for example, less than 1000 ppm, and further, less than 500 ppm. The alkali-free glass is, for example, in the form of a plate and has a thickness of more than 0.5 mm. The ITO layer, for example, is substantially composed of only non-crystalline (amorphous) ITO. However, the ITO layer may also contain impurities other than ITO. The ITO layer can be formed on the surface of alkali-free glass by physical deposition methods such as sputtering.

Next, the test piece is bonded to the ITO layer surface of the glass with the ITO layer using the adhesive layer 1. The bonding of the test piece to the ITO layer is performed using, for example, a laminating machine, and is performed in a manner that prevents bubbles from being mixed between the ITO layer and the adhesive layer 1. After the test piece has been bonded, it is placed in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes to homogenize the bonding between the ITO layer and the adhesive layer 1, and to make the adhesive layer 1 closely adhere to the ITO layer. Next, the test piece (adhesive layer 1) is subjected to a heat treatment for 5 hours in an atmospheric pressure environment at 85°C. Then, place the test piece in an ambient atmosphere at room temperature (e.g., 23°C) to lower the temperature of the test piece to room temperature. Peel the test piece off the ITO layer at a peeling speed of 300 mm/min and a peeling angle of 90° (measured length 80 mm). At this time, measure the force required to peel the test piece off the ITO layer at intervals of 1 time/0.5 s. The average value of the measured values is defined as the adhesion force P ₈₅ .

Test 2 can be performed in the same manner as Test 1 except that the heat treatment after homogenization of the bonding between the ITO layer and the adhesive layer 1 is performed in an autoclave under atmospheric pressure for 24 hours at 105°C.

According to the research of the inventors, when the adhesion force P ₈₅ is below 10.0N/25mm, the heavy workability of the adhesive layer 1 tends to be fully maintained after preheating. The adhesion force P ₈₅ is preferably below 9.0N/25mm, more preferably below 8.0N/25mm, more preferably below 7.0N/25mm, and even more preferably below 6.0N/25mm. From a practical point of view, the lower limit of the adhesion force P ₈₅ is, for example, 3.0N/25mm.

According to the inventors' research, when the adhesion force P ₁₀₅ is greater than 10.0 N/25 mm, the adhesive layer 1 tends to have sufficient durability in a high temperature environment. The adhesion force P ₁₀₅ is preferably greater than 11.0 N/25 mm, more preferably greater than 12.0 N/25 mm, more preferably greater than 13.0 N/25 mm, and even more preferably greater than 14.0 N/25 mm. There is no particular upper limit on the adhesion force P ₁₀₅ , for example, 30.0 N/25 mm.

Furthermore, in the polarizing film 10 with an adhesive layer, the adhesive layer 1 can have an adhesive force _P0 obtained by test 3 of 10.0 N/25 mm or less. Test 3 can be performed in the same manner as test 1, except that the ITO layer and the adhesive layer 1 are homogenized in an autoclave and then not subjected to a heat treatment. The adhesive force _P0 is preferably 9.0 N/25 mm or less, more preferably 8.0 N/25 mm or less, more preferably 7.0 N/25 mm or less, and even more preferably 6.0 N/25 mm or less. From a practical point of view, the lower limit of the adhesive force _P0 is, for example, 3.0 N/25 mm.

[Adhesive layer]

The adhesive layer 1 is formed by an adhesive composition. The adhesive composition contains a compound (C) having an acid group or anhydride group and a polyether compound (D), and further contains, for example, a base polymer. The "base polymer" is, for example, the polymer that contains the most by weight in the adhesive composition, and functions as a component that contributes to the adhesiveness of the adhesive layer 1.

<Compound (C)>

Compound (C) is, for example, a low molecular weight compound or an oligomer. The acid group possessed by compound (C) is, for example, a carboxyl group or an oxalyl group, preferably a carboxyl group. The acid group of compound (C) may also be a group generated by hydrolyzing an acid anhydride group. Specific examples of the acid anhydride group include carboxylic anhydride groups such as succinic anhydride group, phthalic anhydride group, and maleic anhydride group, preferably a succinic anhydride group. The total value of the content of the acid group and the content of the acid anhydride group in compound (C) is not particularly limited, for example, 5.0wt%~50wt%, preferably 8.3wt%~40wt%.

Compound (C) may also contain silicon atoms, and may further contain hydrolyzable groups (h1) bonded to silicon atoms. The hydrolyzable groups (h1) may, for example, form siloxane bonds by hydrolysis reaction and/or condensation reaction. Examples of hydrolyzable groups (h1) include halogen atoms, alkoxy groups, acyloxy groups, alkenyloxy groups, aminoformyl groups, amino groups, aminooxy groups, ketoxime groups, etc. When the hydrolyzable group (h1) has carbon atoms, its carbon number is, for example, 10 or less, preferably 6 or less, and more preferably 4 or less. In particular, alkoxy or alkenyloxy groups with a carbon number of 4 or less are preferred, and methoxy or ethoxy groups are particularly preferred. The content of the hydrolyzable group (h1) in compound (C) is, for example, 10wt% or more, preferably 13wt%~50wt%, and more preferably 13wt%~49wt%.

Compound (C) may also contain other functional groups besides acid groups, acid anhydride groups and hydrolyzable groups (h1), but it is preferred that they do not contain any. As an example, compound (C) does not contain a polyether group.

Compound (C) contains, for example, at least one selected from the group consisting of an alkoxysilane compound (S1) having an acid group or an acid anhydride group, an organic polysiloxane compound (S2) having an acid group or an acid anhydride group, and hydrolyzed condensates thereof, preferably an organic polysiloxane compound (S2).

The alkoxysilane compound (S1) is represented by the following formula (1), for example.

R ¹ R ² _a Si(OR ³ ) _3-a (1)

In formula (1), ^R1 is an organic group with 1 to 20 carbon atoms and an acid group or an acid anhydride group. The organic group may be linear, branched, or cyclic. ^R2 is independent of each other and is a monovalent hydrocarbon group with 1 to 20 carbon atoms that may be substituted by a hydrogen atom or a halogen atom. ^R3 is independent of each other and is an alkyl group with 1 to 10 carbon atoms, preferably a methyl group or an ethyl group. a is 0 or 1.

From the viewpoint of easy availability of the alkoxysilane compound (S1), ^R1 is preferably an organic group represented by the following formula (2).

In formula (2), A is a linear or branched alkylene group or alkenylene group with 2 to 10 carbon atoms, and preferably a linear or branched alkylene group with 2 to 6 carbon atoms. Specific examples of A are ethylene group, propane-1,3-diyl, etc.

Examples of the alkoxysilane compound (S1) include 2-trimethoxysilylethyl succinic anhydride, 3-trimethoxysilylpropyl succinic anhydride (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-12-967C"), 3-triethoxysilylpropyl succinic anhydride, 3-methyldiethoxysilylpropyl succinic anhydride, 1-carboxy-3-triethoxysilylpropyl succinic anhydride, etc.

The organic polysiloxane compound (S2) is a compound having a siloxane bond, and for example contains a siloxane unit (U1) represented by the following formula (3). The organic polysiloxane compound (S2) may further contain a siloxane unit (U2) represented by the following formula (4).

In formula (3), X is an organic group having an acid group or an acid anhydride group, and preferably an organic group represented by formula (2). In formula (3) and formula (4), R ⁴ is independent of each other and is a hydrogen atom, an alkoxy group having 1 to 10 carbon atoms, or a monovalent alkyl group having 1 to 20 carbon atoms which may be substituted by a halogen atom. The alkoxy group of R ⁴ is preferably a methoxy group or an ethoxy group. The alkyl group of R ⁴ is, for example, a methyl group.

The amount of siloxane units (U1) contained in the organic polysiloxane compound (S2) is not particularly limited, for example, 1 to 100, preferably 1 to 50, and more preferably 1 to 20. The amount of siloxane units (U2) contained in the organic polysiloxane compound (S2) is not particularly limited, for example, 0 to 100, preferably 0 to 50, and more preferably 0 to 20. The organic polysiloxane compound (S2) preferably contains at least 1 siloxane unit (U2).

The organic polysiloxane compound (S2) may also have the following structure: at least one siloxane unit (U1) is inserted between the O-Si bonds contained in the alkoxysilane or its partial hydrolyzed condensate represented by the following formula (5). Both the siloxane unit (U1) and the siloxane unit (U2) may be inserted between the O-Si bonds. Among a plurality of O-Si bonds, the siloxane unit (U1) may be inserted between some of the O-Si bonds, and the siloxane unit (U2) may be inserted between the other O-Si bonds.

R ⁵ _n Si(OR ⁶ ) _3-n (5)

In formula (5), R ⁵ is independent of each other and is a monovalent alkyl group having 1 to 20 carbon atoms which may be substituted by a hydrogen atom or a halogen atom. ^{R 6} is independent of each other and is an alkyl group having 1 to 10 carbon atoms. n is 0 or 1.

The alkoxysilane or its partially hydrolyzed condensate represented by formula (5) can be exemplified by tetramethoxysilane, methyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, and compounds in which one or more of these alkoxysilanes have been partially hydrolyzed and condensed.

The organic polysiloxane compound (S2) can be produced by a known production method described in, for example, Japanese Patent Publication No. 2013-129809 and Japanese Patent Publication No. 2013-129691.

As long as the compound (C) has an acid group or an anhydride group, it is not limited to the above-mentioned alkoxysilane compound (S1) and organic polysiloxane compound (S2). The compound (C) may also contain a (meth)acrylic oligomer (B) having an acid group or an anhydride group. For example, the (meth)acrylic oligomer (B) contains a structural unit derived from an alkyl (meth)acrylate as a main component, and also contains a structural unit derived from a (meth)acrylate having an acid group or an anhydride group. In this specification, "(meth)acrylate" means acrylate and/or methacrylate. "Main component" means the structural unit containing the most by weight in the polymer.

Examples of the alkyl (meth)acrylate constituting the (meth)acrylic oligomer (B) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, dibutyl (meth)acrylate, tertiary butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. Examples of (meth)acrylates with acid groups include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and other (meth)acrylates containing carboxyl groups.

Other monomers constituting the (meth)acrylic acid oligomer (B) include, for example, esters of (meth)acrylic acid and alicyclic alcohols such as cyclohexyl (meth)acrylate, isoborneol (meth)acrylate, and dicyclopentyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate and benzyl (meth)acrylate; (meth)acrylates obtained from terpene compound derivative alcohols; ether-bonded alkyl (meth)acrylates such as methoxyethyl (meth)acrylate and phenoxyethyl (meth)acrylate. Such (meth)acrylates can be used alone or in combination of two or more. The monomers constituting the (meth)acrylic acid oligomer (B) can also be monomers constituting the (meth)acrylic acid polymer (A) described later.

The polymerization method of (meth)acrylic acid oligomer (B) is the same as that of (meth)acrylic acid polymer (A) described below, and examples thereof include solution polymerization, emulsion polymerization, block polymerization, emulsion polymerization, polymerization using heat or active energy ray irradiation (thermal polymerization, active energy ray polymerization), etc. Among them, solution polymerization and active energy ray polymerization are preferred from the perspectives of transparency, water resistance, cost, etc. The obtained (meth)acrylic acid oligomer (B) may be any of a random copolymer, a block copolymer, a graft copolymer, etc.

From the perspective of improving the durability, corrosion resistance and heavy workability of the adhesive layer 1, the content of the compound (C) in the adhesive composition is preferably 0.05 to 10 parts by weight, preferably 3 parts by weight or less, more preferably 2 parts by weight or less, particularly preferably 1 part by weight or less, and most preferably 0.6 parts by weight or less, relative to 100 parts by weight of the base polymer. The content of the compound (C) is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, and particularly preferably 0.4 parts by weight or more relative to 100 parts by weight of the base polymer.

The weight average molecular weight of compound (C) is not particularly limited, for example, it is less than 10,000, preferably less than 8,000, more preferably less than 5,000, still more preferably less than 3,000, and particularly preferably less than 1,500. The lower limit of the weight average molecular weight of compound (C) is not particularly limited, for example, it is 100.

Compound (C) may be derived from an acid group and have a low acidity constant pKa. The pKa (especially the first acidity constant) of compound (C) is, for example, 12 or less, preferably 11 or less, more preferably 8 or less, still more preferably 6 or less, and particularly preferably 5 or less. The lower limit of the pKa of compound (C) is not particularly limited, and is, for example, 1. In this specification, pKa is the value in water at 25°C.

<Polyether compound (D)>

The polyether compound (D) is a compound having a polyether skeleton. The polyether skeleton may be a linear chain or a branched chain. The polyether skeleton possessed by the polyether compound (D) contains, for example, an oxyalkylene unit (U3) represented by the following formula (6).

In formula (6), ^R7 is a linear or branched alkylene group having 1 to 10 carbon atoms. The carbon number of ^R7 is preferably 2 to 6, more preferably 3. The polyether compound (D) may contain one or more oxyalkylene units (U3). The polyether compound (D) may be a random copolymer or a block copolymer. Specific examples of the oxyalkylene unit (U3) include oxyethylene, oxypropylene, oxybutylene, etc. From the viewpoint of ease of material production and material stability, the oxyalkylene unit (U3) is preferably oxypropylene (especially _-CH2CH ( _CH3 )O-).

The polyether compound (D) may also contain silicon atoms, and may further contain hydrolyzable groups (h2) bonded to silicon atoms. The hydrolyzable groups (h2) may, for example, form siloxane bonds by hydrolysis reaction and/or condensation reaction. Examples of the hydrolyzable groups (h2) include halogen atoms, alkoxy groups, acyloxy groups, alkenyloxy groups, aminoformyl groups, amino groups, aminooxy groups, ketoxime groups, and the like. When the hydrolyzable group (h2) has carbon atoms, its carbon number is, for example, 10 or less, preferably 6 or less, and more preferably 4 or less. In particular, alkoxy or alkenyloxy groups having a carbon number of 4 or less are preferred, and methoxy or ethoxy groups are particularly preferred. The content of the hydrolyzable groups (h2) in the polyether compound (D) is, for example, 14 wt% or less, preferably less than 13 wt%, and more preferably less than 10 wt%. There is no special limit on the lower limit of the content of the hydrolyzable group (h2), for example, 2.0wt%, 2.5wt%, or 3.0wt%. Depending on the situation, the content of the hydrolyzable group (h2) may be less than 2.0wt%.

The hydrolyzable group (h2) bonded to the silicon atom is, for example, located at the end of the polyether compound (D). As an example, the polyether compound (D) has a reactive silicon group (b) represented by the following formula (7) at at least one end.

-SiR ⁸ _a M _3-a (7)

In formula (7), ^R8 is independent of each other and is a monovalent organic group having 1 to 20 carbon atoms which may have a substituent. ^R8 is preferably a linear or branched alkyl group having 1 to 8 carbon atoms, a fluoroalkyl group having 1 to 8 carbon atoms or a phenyl group, more preferably an alkyl group having 1 to 6 carbon atoms, and most preferably a methyl group. When a plurality of ^R8 are present in the polyether compound (D), the plurality of ^R8 may be the same as or different from each other. M is independent of each other and is a hydroxyl group or a hydrolyzable group (h2). When a plurality of M are present in the polyether compound (D), the plurality of M may be the same as or different from each other. a is an integer of 0 to 2.

For example, the polyether compound (D) has at least one reactive silyl group (b) per molecule at its end. When the polyether compound (D) is in a linear chain, the polyether compound (D) may have one or two reactive silyl groups (b) at its end, preferably two reactive silyl groups (b). When the polyether compound (D) is in a branched chain, the polyether compound (D) has at least one reactive silyl group (b) at the end of the main chain or the end of the side chain. The number of reactive silyl groups (b) can be appropriately adjusted according to the number of ends of the polyether compound (D), preferably more than two, and may be more than three.

The polyether compound (D) preferably has a reactive silicon group (b) at least at a portion of its molecular ends, and has at least 1, preferably 1.1 to 5, and more preferably 1.1 to 3 reactive silicon groups (b) in the molecule.

The reactive silyl group (b) is preferably an alkoxysilyl group (b1) represented by the following formula (8) or an alkoxysilyl group (b2) represented by the following formula (9).

[Chemical formula 6]

In formula (8) and formula (9), R ⁹ , R ¹⁰ and R ¹¹ are each independent of each other and are monovalent hydrocarbon groups having 1 to 6 carbon atoms, such as linear or branched alkyl groups having 1 to 6 carbon atoms, linear or branched alkenyl groups having 2 to 6 carbon atoms, cycloalkyl groups having 5 to 6 carbon atoms, phenyl groups, etc. Specific examples of -OR ⁹ , -OR ¹⁰ and -OR ¹¹ in formula (8) and formula (9) include methoxy groups, ethoxy groups, propoxy groups, propenyloxy groups, phenoxy groups, etc., preferably methoxy groups and ethoxy groups, and particularly preferably methoxy groups.

The polyether compound (D) preferably has a main chain substantially composed of a polyether skeleton in addition to the reactive silyl group (b). However, the main chain of the polyether compound (D) may also contain a small amount of other chemical structures. Other chemical structures may include, for example, the chemical structure of the initiator used to form the oxyalkylene unit (U3), and the linking group between the polyether skeleton and the reactive silyl group (b). The content of the oxyalkylene unit (U3) in the polyether compound (D) is preferably 50% by weight or more, and more preferably 80% by weight or more.

The polyether compound (D) is represented by the following formula (10), for example.

R ¹² _a M _3-a Si-XY-(AO) _n -Z (10)

In formula (10), R ¹² is independent of each other and is a monovalent organic group having 1 to 20 carbon atoms which may have a substituent. M is independent of each other and is a hydroxyl group or a hydrolyzable group (h2). a is an integer of 0 to 2. AO is a linear or branched oxyalkylene group having 1 to 10 carbon atoms. n represents the average added molar number of the oxyalkylene group and is 1 to 1700. X is a linear or branched alkylene group having 1 to 20 carbon atoms. Y is an ether bond, an ester bond, a urethane bond or a carbonate bond. Z is a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a group represented by the following formula (11) or a group represented by the following formula (12).

-Y ¹ -X-SiR ¹² _a M _3-a (11)

-Q{-(OA) _n -YX-SiR ¹² _a M _3-a } _m (12)

In formula (11), R ¹² , M and X are the same as those in formula (10). ^{Y 1} is a single bond, a -CO- bond, a -CONH- bond or a -COO- bond. In formula (12), R ¹² , M, X, Y and n are the same as those in formula (10). OA is the same as AO in formula (10). Q is a divalent or higher alkyl group having 1 to 10 carbon atoms. m is the alkyl group valence of Q minus 1.

X in formula (10) is a linear or branched alkylene group with 1 to 20 carbon atoms. The alkylene group preferably has 2 to 10 carbon atoms, more preferably 3 carbon atoms.

Y in formula (10) is a bond formed by the reaction of the oxyalkylene group at the end of the polyether skeleton and the hydroxyl group, preferably an ether bond or a urethane bond, more preferably a urethane bond.

Z is derived from, for example, an initiator used in the synthesis of an oxyalkylene polymer, i.e., a hydroxyl compound, and the aforementioned oxyalkylene polymer is used in the preparation of the polyether compound (D) represented by formula (10). Z is, for example, a hydrogen atom or a monovalent carbonyl group having 1 to 10 carbon atoms. In this case, the polyether compound (D) represented by formula (10) has a reactive silicon group (b) at its end. When Z is a hydrogen atom, it is equivalent to the case where the hydroxyl compound uses the same structural unit as the oxyalkylene polymer. When Z is a monovalent carbonyl group having 1 to 10 carbon atoms, it is equivalent to the case where a hydroxyl compound having 1 hydroxyl group is used.

On the other hand, when Z is represented by formula (11) or formula (12), the polyether compound (D) has a plurality of reactive silyl groups (b) at its terminal. When Z is represented by formula (11), it is equivalent to the case where the hydroxyl compound uses the same structural unit as the oxyalkylene polymer. When Z is represented by formula (12), it is equivalent to the case where a hydroxyl compound having two hydroxyl groups and a structural unit different from that of the oxyalkylene polymer is used. In addition, ^Y1 in formula (11) is the same as Y in formula (10), and is a bond formed by the reaction of the oxyalkylene group at the terminal of the polyether skeleton with the hydroxyl group.

From the viewpoint of heavy workability, the polyether compound (D) is preferably represented by the following formula (13), formula (14) or formula (15).

Z ⁰ -A ² -O-(A ¹ O) _n -Z ¹ (13)

Z ⁰ -A ² -NHCOO-(A ¹ O) _n -Z ² (14)

Z ³ -O-(A ¹ O) _n -CH{-CH ₂ -(A ¹ O) _n -Z ³ } ₂ (15)

In formula (13) to (15), ^Z0 is an alkoxysilyl group represented by formula (8) or (9). ^A1O is an oxyalkylene group having 2 to 6 carbon atoms, preferably an oxypropylene group. The oxyalkylene group of ^A1O may be a linear chain or a branched chain. n represents the average addition molar number of ^A1O , which is 1 to 1700. ^A2 in formula (13) and formula (14) is an alkylene group having 2 to 6 carbon atoms, preferably ^an alkylene group. The alkylene group of ^A2 may be a linear chain or a branched chain. ^Z1 in formula (13) is a hydrogen atom or -A2- ^Z0 . ^Z2 in formula (14) is a hydrogen atom or -CONH- ^A2 - ^Z0 . In formula (15), Z ³ is a hydrogen atom or -A ² -Z ⁰ , and at least one Z ³ is -A ² -Z ⁰ .

The compound represented by formula (14) is preferably, for example, a compound represented by the following formula (16).

In formula (16), R ⁹ , R ¹⁰ and R ¹¹ are each independent of each other and are monovalent hydrocarbon groups having 1 to 6 carbon atoms. n represents the average number of moles of oxypropylene groups added and is 1 to 1700. ^{Z 21} is a hydrogen atom or a trialkoxysilyl group represented by the following formula (17).

In the formula (17), R ⁹ , R ¹⁰ and R ¹¹ are the same as those in the formula (16).

From the viewpoint of heavy workability, the number average molecular weight of the polyether compound (D) is preferably 300 to 100,000. The number average molecular weight is preferably 500 or more, further 1,000 or more, further 2,000 or more, further 3,000 or more, further 4,000 or more, further 5,000 or more, and preferably 50,000 or less, further 40,000 or less, further 30,000 or less, further 20,000 or less, further 10,000 or less. n (the average added molar number of oxyalkylene groups in the polyether skeleton) in the above formulas (10) to (16) can be appropriately adjusted, for example, so that the number average molecular weight of the polyether compound (D) is within the above range. When the number average molecular weight of the polyether compound (D) is 1,000 or more, the above n is usually 10 to 1,700.

The Mw (weight average molecular weight)/Mn (number average molecular weight) of the polyether compound (D) is preferably less than 3.0, more preferably less than 1.6, and particularly preferably less than 1.5. In order to obtain a polyether compound (D) with a small Mw/Mn, the following method is preferably used: using the following composite metal cyanide complex as a catalyst, and in the presence of an initiator, polymerizing a cyclic ether to obtain an oxyalkylene polymer, and modifying the terminal of the oxyalkylene polymer to introduce a reactive silicon group.

The polyether compound (D) can be produced, for example, as follows: an oxyalkylene polymer having a functional group at the molecular end is used as a raw material, and a reactive silicon group is bonded to the molecular end through an organic group such as an alkylene group. The oxyalkylene polymer used as a raw material is preferably a polymer having a hydroxyl group at the terminal obtained by ring-opening polymerization of a cyclic ether in the presence of a catalyst and an initiator.

The above-mentioned initiator can use a compound having more than one active hydrogen atom per molecule, such as a hydroxy compound having more than one hydroxy group per molecule. Examples of the initiator include: ethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, hexamethylene glycol, hydrogenated bisphenol A, neopentyl glycol, polybutadiene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, allyl alcohol, methyl allyl alcohol, glycerol, trihydroxymethylmethane, trihydroxymethylpropane, neopentyltrol and hydroxy compounds such as alkylene oxide adducts thereof. The initiator can be one or more than two.

When a cyclic ether is subjected to ring-opening polymerization in the presence of an initiator, a polymerization catalyst can be used. Examples of polymerization catalysts include: alkali metal compounds such as potassium hydroxide and potassium methoxide, cesium compounds such as cesium hydroxide, complex metal cyanide complexes, metal porphyrin complexes, compounds with a P=N bond, etc.

The polyether skeleton (polyoxyalkylene chain) in the polyether compound (D) is preferably composed of oxyalkylene units formed by ring-opening polymerization of alkylene oxides having 2 to 6 carbon atoms, more preferably composed of oxyalkylene units formed by ring-opening polymerization of at least one oxyalkylene oxide selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide, and particularly preferably composed of oxyalkylene units formed by ring-opening polymerization of propylene oxide. When the polyoxyalkylene chain is composed of two or more oxyalkylene units, the arrangement of the two or more oxyalkylene units may be block-shaped or random.

The polyether compound (D) represented by the above formula (14) can be prepared, for example, by the following method: for a polymer having a polyoxyalkylene chain and a hydroxyl group, a compound having a reactive silyl group (b) and an isocyanate group is used to carry out a urethanization reaction. The polyether compound (D) represented by the formula (14) can also be prepared by the following method: on an oxyalkylene polymer having an unsaturated group, for example, an allyl-terminated polyoxypropylene monol obtained by polymerizing epoxide using allyl alcohol as an initiator, a hydrosilane or a silyl group is added to the unsaturated group to introduce a reactive silyl group (b) at the molecular end.

There is no particular limitation on the method of introducing a reactive silyl group (b) into the terminal group of a hydroxyl-terminated oxyalkylene polymer obtained by ring-opening polymerization of a cyclic ether in the presence of an initiator. Generally, the following methods (a) to (c) are preferably used, wherein the terminal group is further linked to the reactive silyl group via an organic group.

(a) A method of introducing an unsaturated group into the terminal of an oxyalkylene polymer having a hydroxyl group and then bonding a reactive silicon group (b) to the unsaturated group.

This method can be further exemplified by the following two methods (a-1) and (a-2).

(a-1) A method of so-called silylation reaction in which a silane compound is reacted with the above-mentioned unsaturated group in the presence of a catalyst such as a platinum compound.

(a-2) A method of reacting a silane compound with an unsaturated group.

Examples of the silane compound (a-2) include 3-butyltrimethoxysilane, 3-butyltriethoxysilane, 3-butyltriisopropenyloxysilane, 3-butylmethyldimethoxysilane, 3-butyldimethylmonomethoxysilane, 3-butylmethyldiethoxysilane, etc.

When the unsaturated group and the alkyl group are reacted, a compound such as a free radical generator used as a free radical polymerization initiator may be used, or the reaction may be carried out using radiation or heat without using a free radical polymerization initiator as desired. Examples of free radical polymerization initiators include peroxide-based, azo-based, and redox-based polymerization initiators and metal compound catalysts, and specifically, examples include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, benzoyl peroxide, tertiary alkyl peroxide, acetyl peroxide, and diisopropyl peroxycarbonate. The reaction conditions when using free radical polymerization initiators to make unsaturated groups react with hydroxyl groups vary according to the decomposition temperature (half-life temperature) of the polymerization initiator. For example, the reaction temperature is preferably 20~200℃, preferably 50~150℃, and the reaction is carried out for several hours to dozens of hours.

The method of introducing an unsaturated group at the end of an oxyalkylene polymer may be exemplified by the following method: reacting a reactant with an oxyalkylene polymer, wherein the reactant has a functional group that can be linked to the terminal hydroxyl group of the oxyalkylene polymer by an ether bond, an ester bond, a urethane bond, or a carbonate bond, and an unsaturated group. The following method may also be used: when polymerizing a cyclic ether in the presence of an initiator, copolymerizing an epoxy compound containing an unsaturated group such as allyl epoxypropyl ether, thereby introducing an unsaturated group at least partially at the end of the oxyalkylene polymer.

The silicification reaction is preferably carried out at a temperature of 60~120℃. Generally speaking, the silicification reaction can be fully carried out within a few hours.

(b) A method of reacting an oxyalkylene polymer having a hydroxyl group at the end with an isocyanate silane compound having a reactive silyl group (b).

Examples of the isocyanate silane compound include 1-isocyanate methyl trimethoxy silane, 1-isocyanate methyl triethoxy silane, 1-isocyanate propyl trimethoxy silane, 1-isocyanate propyl triethoxy silane, 3-isocyanate propyl trimethoxy silane, 3-isocyanate propyl triethoxy silane, 1-isocyanate methyl methyl dimethoxy silane, 1-isocyanate methyl dimethyl monomethoxy silane, Isocyanate silane compounds such as silane, 1-isocyanate methyl methyl diethoxy silane, 1-isocyanate propyl methyl dimethoxy silane, 1-isocyanate propyl dimethyl monomethoxy silane, 1-isocyanate propyl methyl diethoxy silane, 3-isocyanate propyl methyl dimethoxy silane, 3-isocyanate propyl dimethyl monomethoxy silane and 3-isocyanate propyl methyl diethoxy silane. Among them, 3-isocyanate propyl trimethoxy silane and 1-isocyanate methyl methyl dimethoxy silane are more preferred, and 3-isocyanate propyl trimethoxy silane is particularly preferred.

The reaction of the oxyalkylene polymer and the isocyanate silane compound is preferably carried out at a molar ratio of the isocyanate group (NCO) of the isocyanate silane compound to the hydroxyl group (OH) of the oxyalkylene polymer of NCO/OH=0.80~1.05. This method has a small number of manufacturing steps, so the step time can be greatly shortened. In addition, there are few impurities produced during the manufacturing steps, so there is no need for complicated operations such as purification. The more ideal molar ratio of NCO group to OH group is NCO/OH=0.85~1.00. When the NCO ratio is low, the residual OH group will react with the reactive silane group, thereby reducing the storage stability. In this case, it is advisable to re-react with an isocyanate silane compound or a monoisocyanate compound to consume the excess OH groups and thereby adjust to the predetermined silicidation rate.

When the hydroxyl group of the oxyalkylene polymer reacts with the above-mentioned isocyanate silane compound, a known urethanization catalyst can also be used. Depending on whether the urethanization catalyst is used and the amount used, the reaction temperature and the reaction time required before the reaction is completed will be different. The reaction of the oxyalkylene polymer and the isocyanate silane compound is preferably carried out at a temperature of 20~200℃, preferably 50~150℃ for several hours.

(c) A method of reacting a polyisocyanate compound with an oxyalkylene polymer having a hydroxyl group at the molecular end under the condition of excess isocyanate groups to produce an oxyalkylene polymer having an isocyanate group at at least a portion of the terminal, and then reacting a silicon compound having a functional group with the isocyanate group.

The functional group of the silicon compound is at least one group containing active hydrogen selected from the group consisting of hydroxyl, carboxyl, butyl, primary amine and secondary amine. Examples of the silicon compound include aminosilane compounds such as N-phenyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane; and butylsilane compounds such as 3-butyltrimethoxysilane and 3-butylmethyldimethoxysilane. When reacting the oxyalkylene polymer with the above silicon compound, a known urethanization catalyst may also be used. Depending on whether or not a catalyst is used in the urethanization reaction and the amount used, the reaction temperature and the reaction time required for the reaction to be completed will be different. For example, the above reaction is preferably carried out at a temperature of 20-200°C, preferably 50-150°C, for several hours.

Specific examples of polyether compounds (D) include: MS polymers S203, S303, S810 manufactured by KANEKA Corporation; SILYL EST250, EST280; SAT10, SAT200, SAT220, SAT350, SAT400; EXCESTAR S2410, S2420, S3430 manufactured by Asahi Glass Co., Ltd., etc.

The content of the polyether compound (D) in the adhesive composition is preferably 0.001 to 20 parts by weight relative to 100 parts by weight of the base polymer. By making the content above 0.001 parts by weight, there is a tendency that the workability of the adhesive layer 1 is sufficiently improved. The content of the polyether compound (D) is preferably above 0.01 parts by weight, and more preferably above 0.02 parts by weight, further above 0.1 parts by weight, and further above 0.5 parts by weight. When the content of the polyether compound (D) is below 20 parts by weight, the adhesive layer 1 has sufficient moisture resistance and is not prone to peeling in reliability tests, etc. The content of the polyether compound (D) is preferably below 10 parts by weight, and more preferably below 5 parts by weight, and further below 3 parts by weight. The content of the polyether compound (D) may also be below 1 part by weight, and further below 0.5 parts by weight.

<Adhesive>

Adhesives contained in the adhesive composition include, for example, rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, cellulose adhesives, etc. From the perspective of excellent optical transparency, moderate wettability, cohesion, adhesion and other adhesive properties, as well as excellent weather resistance and heat resistance, the adhesive is preferably an acrylic adhesive.

The adhesive composition containing an acrylic adhesive contains a (meth)acrylic polymer (A) as a base polymer. The (meth)acrylic polymer (A) contains, for example, a structural unit derived from an alkyl (meth)acrylate as a main component.

<(Meth)acrylic acid polymer (A)>

The carbon number of the alkyl group contained in the (meth)acrylic acid alkyl ester used to form the main skeleton of the (meth)acrylic polymer (A) is not particularly limited, and is, for example, 1 to 18. The alkyl group may be a straight chain, a branched chain, or a ring. Examples of the alkyl group include: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, etc. (meth)acrylic acid alkyl esters may be used alone or in combination. The average carbon number of the alkyl group is preferably 3 to 9.

The monomers constituting the (meth)acrylic acid polymer (A) may be, in addition to (meth)acrylic acid alkyl esters, one or more copolymer monomers selected from the group consisting of aromatic ring-containing (meth)acrylic acid esters, amide-containing monomers, carboxyl-containing monomers, and hydroxyl-containing monomers. The copolymer monomers may be used alone or in combination. The (meth)acrylic acid polymer (A) preferably has an acid group derived from a copolymer monomer such as a carboxyl-containing monomer. The (meth)acrylic acid polymer (A) having an acid group is suitable for maintaining the heavy workability of the adhesive layer 1 after preheating.

Aromatic ring-containing (meth)acrylate is a compound containing an aromatic ring structure and a (meth)acryloyl group in its structure. Examples of aromatic rings include benzene rings, naphthalene rings, biphenyl rings, etc. Aromatic ring-containing (meth)acrylate has the effect of adjusting the phase difference generated when stress is applied to the adhesive layer 1 due to the contraction of optical films such as polarizing films 2, and can suppress light leakage caused by the contraction of optical films.

Examples of the (meth)acrylate containing an aromatic ring include benzyl (meth)acrylate, phenyl (meth)acrylate, o-phenylphenol (meth)acrylate, phenoxy (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, ethylene oxide modified nonylphenol (meth)acrylate, ethylene oxide modified cresol (meth)acrylate, phenol ethylene oxide modified (meth)acrylate, Those having a benzene ring, such as 2-hydroxy-3-phenoxypropyl (meth)acrylate, methoxybenzyl (meth)acrylate, benzyl (meth)acrylate chloride, toluene (meth)acrylate, polystyrene (meth)acrylate, etc.; those having a naphthyl ring, such as hydroxyethylated β-naphthol acrylate, 2-naphthylethyl (meth)acrylate, 2-naphthyloxyethyl acrylate, 2-(4-methoxy-1-naphthyloxy)ethyl (meth)acrylate, etc.; those having a biphenyl ring, such as biphenyl (meth)acrylate, etc. Among them, benzyl (meth)acrylate and phenoxyethyl (meth)acrylate are preferred from the viewpoint of improving the adhesive properties or durability of the adhesive layer 1.

啉、N-(甲基)丙烯醯基哌啶、N-(甲基)丙烯醯基吡咯啶等N-丙烯醯基雜環單體；N-乙烯基吡咯啶酮、N-乙烯基-ε-己內醯胺等含N-乙烯基之內醯胺系單體等。該等之中，從提升黏著劑層1對導電層之耐久性之觀點來看，又以含N-乙烯基之內醯胺系單體為佳。 The amide group-containing monomer is a compound having an amide group and a polymerizable unsaturated double bond such as a (meth)acryl group or a vinyl group in its structure. Examples of the amide group-containing monomer include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxymethyl-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, ethylmethyl(meth)acrylamide, ethylethyl(meth)acrylamide and the like acrylamide monomers; N-(meth)acrylamide

N-(methyl)acrylpiperidine, N-(methyl)acrylpyrrolidine and other N-acryl heterocyclic monomers; N-vinylpyrrolidone, N-vinyl-ε-caprolactam and other N-vinyl lactam monomers, etc. Among them, from the perspective of improving the durability of the adhesive layer 1 to the conductive layer, the N-vinyl lactam monomer is preferred.

The carboxyl-containing monomer is a compound containing a carboxyl group and a polymerizable unsaturated double bond such as a (meth)acrylic acid group and a vinyl group in its structure. Examples of the carboxyl-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, etc. Among them, acrylic acid is preferred from the perspective of copolymerizability, price, and improving the adhesive properties of the adhesive layer 1.

A hydroxyl-containing monomer is a compound containing a hydroxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryl group or a vinyl group. Examples of hydroxyl-containing monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; (4-hydroxymethylcyclohexyl)-methacrylate, and the like. Among them, from the perspective of improving the durability of the adhesive layer 1, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 4-hydroxybutyl (meth)acrylate is more preferred.

The copolymer monomer will become a reaction point with the crosslinking agent. Carboxyl-containing monomers and hydroxyl-containing monomers are rich in reactivity with intermolecular crosslinking agents, so they are suitable for improving the cohesion or heat resistance of the adhesive layer 1. Carboxyl-containing monomers are better in terms of both durability and workability, while hydroxyl-containing monomers are better in terms of improving workability.

From the perspective of improving the adhesion of the adhesive layer 1, the ratio of the (meth)acrylate alkyl ester to the total monomer components forming the (meth)acrylic polymer (A) is preferably 50% by weight or more.

When using an aromatic ring-containing (meth)acrylate as a monomer component, from the perspective of improving the durability of the adhesive layer 1, the ratio of the aromatic ring-containing (meth)acrylate to the total monomer components forming the (meth)acrylic polymer (A) is preferably 3 to 25% by weight, preferably 22% by weight or less, and more preferably 20% by weight or less. The ratio is more preferably 8% by weight or more, and more preferably 12% by weight or more. By adjusting the copolymerization rate of the aromatic ring-containing (meth)acrylate to the above range, light leakage caused by the shrinkage of the optical film can be suppressed, and there is a tendency to improve the workability of the adhesive layer 1.

When a hydroxyl-containing monomer is used as a monomer component, from the perspective of improving the adhesive properties and durability of the adhesive layer 1, the ratio of the hydroxyl-containing monomer to the total monomer components forming the (meth)acrylic polymer (A) is preferably 0.01-10% by weight, preferably 5% by weight or less, more preferably 2% by weight or less, and particularly preferably 1% by weight or less. The ratio is more preferably 0.03% by weight or more, and more preferably 0.05% by weight or more. By adjusting the copolymerization rate of the hydroxyl-containing monomer to the above range, the adhesive can be fully crosslinked in the adhesive layer 1, and the adhesive is inhibited from hardening, thereby tending to improve the durability of the adhesive layer 1.

In addition to the (meth)acrylic acid alkyl ester and the above-mentioned copolymer monomers, other copolymer monomers having polymerizable functional groups containing unsaturated double bonds such as (meth)acrylic acid or vinyl groups may be used as monomer components for the purpose of improving the adhesion and heat resistance of the adhesive layer 1. Other copolymer monomers may be used alone or in combination.

Other copolymer monomers include, for example, monomers containing anhydride groups such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; monomers containing sulfonic acid groups such as allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, and sulfopropyl (meth)acrylate; monomers containing phosphate groups such as 2-hydroxyethylacryl phosphate; (meth)acrylic acid aminoethyl esters such as (meth)acrylic acid N,N-dimethylaminoethyl ester and (meth)acrylic acid tertiary butylaminoethyl ester; (meth)acrylic acid methoxyethyl ester and (meth)acrylic acid ethoxyethyl ester; esters, etc.; succinimide monomers such as N-(meth)acryloxymethylenesuccinimide, N-(meth)acryl-6-oxyhexamethylenesuccinimide, N-(meth)acryl-8-oxyoctylsuccinimide, etc.; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.; N-methyliconimide, N-ethyliconimide, N-butyliconimide, N-octyliconimide, N-2-ethylhexyliconimide , N-cyclohexylicarboxyliconimide, N-lauryliconimide and other icarboxyliconimide monomers; vinyl acetate, vinyl propionate and other vinyl monomers; acrylonitrile, methacrylonitrile and other cyanoacrylate monomers; epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate and other glycol (meth)acrylates; tetrahydrofurfuryl (meth)acrylate, fluoro (meth)acrylate, polysilicone (meth)acrylate, propylene glycol (meth)acrylate and other (meth)acrylates; (Meth)acrylate monomers such as 2-methoxyethyl acrylate; silane monomers containing silicon atoms such as 3-acryloxypropyl triethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, 4-vinyl butyl trimethoxysilane, 4-vinyl butyl triethoxysilane, 8-vinyl octyl trimethoxysilane, 8-vinyl octyl triethoxysilane, 10-methacryloxy decyl trimethoxysilane, 10-acryloxy decyl trimethoxysilane, 10-methacryloxy decyl triethoxysilane, 10-acryloxy decyl triethoxysilane, etc.

Furthermore, other copolymer monomers include, for example, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, neopentyl glycol di(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and other multifunctional monomers having two or more unsaturated double bonds.

When other copolymers are used as monomer components, the ratio of other copolymers to the total monomer components forming the (meth)acrylic polymer (A) is preferably 10% by weight or less, preferably 7% by weight or less, and more preferably 5% by weight or less.

<Method for producing (meth)acrylic acid polymer (A)>

The (meth)acrylic polymer (A) can be produced by known polymerization methods such as solution polymerization, electron beam or UV radiation polymerization, block polymerization, emulsion polymerization and other free radical polymerization. The produced (meth)acrylic polymer (A) can be any of a random copolymer, a block copolymer, a graft copolymer and the like.

In solution polymerization, the polymerization solvent may be ethyl acetate, toluene, etc. Solution polymerization is carried out under reaction conditions of about 50-70°C and about 5-30 hours by adding a polymerization initiator under an inert gas flow such as nitrogen.

The polymerization initiator, chain transfer agent, emulsifier, etc. used for free radical polymerization are not particularly limited and can be appropriately selected. The weight average molecular weight of the (meth)acrylic polymer (A) can be controlled by the amount of polymerization initiator and chain transfer agent used, reaction conditions, etc. Therefore, the amount of polymerization initiator and chain transfer agent used can be appropriately adjusted according to their composition.

Examples of polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-carboxamidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(N Azo initiators such as 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate (Wako Pure Chemical Industries, Ltd., VA-057); persulfates such as potassium persulfate and ammonium persulfate; di(2-ethylhexyl) peroxydicarbonate, di(4-tert-butyl) peroxydicarbonate Peroxide initiators such as cyclohexyl) ester, di-butyl peroxydicarbonate, tertiary butyl peroxyneodecanoate, tertiary hexyl peroxytrimethylacetate, tertiary butyl peroxytrimethylacetate, dilauryl peroxide, di-n-octyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, dibenzoyl peroxide, tertiary butyl peroxyisobutyrate, 1,1-di(tertiary hexylperoxy)cyclohexane, tertiary butyl hydroperoxide, hydrogen peroxide, etc.; redox initiators in which peroxide and a reducing agent are combined, such as a combination of persulfate and sodium bisulfite, a combination of peroxide and sodium ascorbate, etc., but are not limited to the above.

The polymerization initiator can be used alone or in combination. The total usage is preferably about 0.005 to 1 part by weight, and more preferably about 0.01 to 0.5 part by weight, relative to 100 parts by weight of the monomer component.

Chain transfer agents include, for example, lauryl mercaptan, glycidyl mercaptan, ethylene glycol, 2-ethylhexyl thioglycolate, 2,3-diethylene-1-propanol, etc. Chain transfer agents can be used alone or in combination of two or more. The total amount used is less than 0.1 parts by weight relative to 100 parts by weight of the monomer component.

Emulsifiers used in emulsion polymerization include, for example, anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, polyoxyethylene alkyl ether ammonium sulfate, polyoxyethylene alkyl phenyl ether sodium sulfate, and nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene-polyoxypropylene block polymer, etc. Emulsifiers can be used alone or in combination.

Reactive emulsifiers include emulsifiers that have been introduced with free radical polymerizable functional groups such as propylene and allyl ether groups. Specific examples of such emulsifiers include: AQUALON HS-10, HS-20, KH-10, BC-05, BC-10, BC-20 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), ADEKA REASOAP SE10N (manufactured by ADEKA Corporation), etc. Reactive emulsifiers are more ideal because they will be incorporated into the polymer chain after polymerization and improve water resistance. The amount of emulsifier used is preferably 0.3 to 5 parts by weight relative to the total amount of 100 parts by weight of the monomer components, and is more preferably 0.5 to 1 part by weight in terms of polymerization stability or mechanical stability.

Radiation polymerization is to polymerize the monomer components by irradiating them with radiation such as electron rays, UV rays, etc., and to produce a (meth)acrylic polymer (A). When radiation polymerization is performed using electron rays, it is not necessary to specifically make the monomer components contain a photopolymerization initiator. When radiation polymerization is performed using UV, the monomer components may contain a photopolymerization initiator for the advantage of shortening the polymerization time. Photopolymerization initiators may be used alone or in combination.

(thioxanthone)系等。光聚合引發劑之使用量相對於單體成分100重量份為0.05~1.5重量份，較佳為0.1~1重量份。光聚合引發劑可單獨或組合使用。 The photopolymerization initiator is not particularly limited as long as it can initiate photopolymerization, and commonly used photopolymerization initiators can be used. For example, benzoin ether-based, acetophenone-based, α-ketol-based, photoactive oxime-based, benzoin-based, diphenylethylene-based, diphenyl ketone-based, ketal-based, 9-oxysulfur-based,

(thioxanthone) series, etc. The amount of the photopolymerization initiator used is 0.05 to 1.5 parts by weight, preferably 0.1 to 1 part by weight, relative to 100 parts by weight of the monomer component. The photopolymerization initiator can be used alone or in combination.

The weight average molecular weight of the (meth)acrylic polymer (A) is usually 1 million to 2.5 million. If durability, especially heat resistance, is taken into consideration, the weight average molecular weight of the (meth)acrylic polymer (A) is preferably 1.2 million to 2 million. A weight average molecular weight of 1 million or more is more ideal from the perspective of heat resistance. If the weight average molecular weight is less than 2.5 million, the adhesive is less likely to harden and tends to be less likely to peel off. The weight average molecular weight (Mw)/number average molecular weight (Mn) of the molecular weight distribution is preferably 1.8 to 10, preferably 1.8 to 7, and more preferably 1.8 to 5. A molecular weight distribution (Mw/Mn) of less than 10 is more ideal from the perspective of durability. The weight average molecular weight and molecular weight distribution (Mw/Mn) are measured by GPC (gel permeation chromatography) and obtained from the values calculated based on polystyrene conversion.

<Silane coupling agent>

In addition to the compound (C) and the polyether compound (D), the adhesive composition may further contain a silane coupling agent (E). The silane coupling agent (E) may have a reactive functional group other than an acid group and an anhydride group. The reactive functional group is preferably at least one selected from the group consisting of an epoxy group, an amine group, an isocyanate group, a triisocyanate group, a vinyl group, a styrene group, an acetyl group, a urea group, a thiourea group, a (meth)acryl group and a heterocyclic group. The silane coupling agent (E) may be used alone or in combination.

The silane coupling agent (E) may include, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and other silane coupling agents containing epoxy groups; 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, N ... -phenyl-γ-aminopropyl trimethoxysilane and other amino group-containing silane coupling agents; 3-isocyanate propyl triethoxysilane and other isocyanate group-containing silane coupling agents; vinyl trimethoxy silane, vinyl triethoxy silane and other vinyl group-containing silane coupling agents; p-phenylene trimethoxy silane and other styrene group-containing silane coupling agents; 3-acryloxypropyl trimethoxy silane, 3-methacryloxypropyl triethoxy silane and other (meth)acryl group-containing silane coupling agents, etc. Among them, epoxy group-containing silane coupling agents are preferred.

Silane coupling agent (E) can also be used in silane coupling agents having multiple alkoxy silane groups in the molecule (oligomer silane coupling agent). Specific examples of oligomer silane coupling agents include: oligomer silane coupling agents containing epoxy groups manufactured by Shin-Etsu Chemical Co., Ltd., with trade names such as "X-41-1053", "X-41-1059A", "X-41-1056", "X-40-2651", etc. Oligomer silane coupling agents are not easy to volatilize, and have multiple alkoxy silane groups, so they can effectively improve the durability of the adhesive layer 1, so they are better.

When the adhesive composition contains a silane coupling agent (E), the content of the silane coupling agent (E) in the adhesive composition is preferably 0.001 to 5 parts by weight relative to 100 parts by weight of the base polymer, preferably less than 1 part by weight, and more preferably less than 0.6 parts by weight. The content of the silane coupling agent (E) relative to 100 parts by weight of the base polymer is more preferably 0.01 parts by weight or more, and more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more. By appropriately adjusting the content of the silane coupling agent (E), the durability of the adhesive layer 1 tends to be improved.

When the adhesive composition contains a silane coupling agent (E), from the perspective of improving the durability of the adhesive layer 1, the weight ratio of the compound (C) to the silane coupling agent (E) (compound (C)/silane coupling agent (E)) is preferably 0.1 or more, preferably 0.5 or more, more preferably 1 or more, and preferably 50 or less, preferably 15 or less, and more preferably 5 or less.

<Crosslinking agent>

The adhesive composition may further contain a crosslinking agent. The crosslinking agent may be an organic crosslinking agent, a multifunctional metal chelate, etc. Examples of organic crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. Multifunctional metal chelates are covalently bonded or coordinately bonded polyvalent metal atoms and organic compounds. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Covalently bonded or coordinately bonded organic compounds include, for example, oxygen atoms, and preferably, alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds. Crosslinking agents can be used alone or in combination.

The crosslinking agent is preferably an isocyanate crosslinking agent and/or a peroxide crosslinking agent, and more preferably, an isocyanate crosslinking agent and a peroxide crosslinking agent are used together.

Isocyanate crosslinking agents may be compounds having at least two isocyanate groups (including isocyanate regeneration functional groups that have been temporarily protected by blocking agents or polymerization). For example, well-known aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, etc., which are generally used for urethanization reactions, may be used.

Aliphatic polyisocyanates include, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propyl diisocyanate, 1,3-butyl diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc.

Examples of alicyclic isocyanates include: 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, diisocyanate, toluene diisocyanate, tetramethylol diisocyanate, etc.

Aromatic diisocyanates include, for example, phenyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, stubyl diisocyanate, etc.

Examples of isocyanate crosslinking agents include: polymers (dimers, trimers, pentamers, etc.) of the above-mentioned diisocyanates, urethane modified products reacted with polyols such as trihydroxymethylpropane, urea modified products, biuret modified products, allophanate modified products, isocyanurate modified products, carbodiimide modified products, etc.

Examples of commercially available isocyanate crosslinking agents include: Tosoh Corporation’s products “Millionate MT”, “Millionate MTL”, “Millionate MR-200”, “Millionate MR-400”, “Coronate L”, “Coronate HL”, “Coronate HX”, and Mitsui Chemicals’ products “TAKENATE D-110N”, “TAKENATE D-120N”, “TAKENATE D-140N”, “TAKENATE D-160N”, “TAKENATE D-165N”, “TAKENATE D-170HN”, “TAKENATE D-178N”, “TAKENATE500”, “TAKENATE600”, etc.

Isocyanate crosslinking agents are preferably aromatic polyisocyanates and their modified aromatic polyisocyanate compounds, aliphatic polyisocyanates and their modified aliphatic polyisocyanate compounds. Aromatic polyisocyanate compounds have a good balance between crosslinking speed and pot life and are suitable for use. Among aromatic polyisocyanate compounds, toluene diisocyanate and its modified products are particularly preferred.

As peroxides, any peroxide that generates free radical active species upon heating or light irradiation to crosslink the base polymer of the adhesive composition (e.g., (meth)acrylic polymer (A)) can be used appropriately. However, in consideration of workability or stability, peroxides with a half-life temperature of 80°C to 160°C per minute are preferred, and peroxides with a half-life temperature of 90°C to 140°C are more preferred.

Peroxides include, for example, di(2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6°C), di(4-tert-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1°C), di-di-butyl peroxydicarbonate (1 minute half-life temperature: 92.4°C), tri-butyl peroxyneodecanoate (1 minute half-life temperature: 103.5°C), tri-hexyl peroxypivalate (1 minute half-life temperature: 109.1°C), tri-butyl peroxypivalate (1 minute half-life temperature: 110.3°C), dilauryl peroxide (1 Half-life temperature of 1 minute: 116.4℃), dioctyl peroxide (half-life temperature of 1 minute: 117.4℃), 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (half-life temperature of 1 minute: 124.3℃), di(4-methylbenzoyl) peroxide (half-life temperature of 1 minute: 128.2℃), dibenzoyl peroxide (half-life temperature of 1 minute: 130.0℃), tertiary butyl peroxyisobutyrate (half-life temperature of 1 minute: 136.1℃), 1,1-di(tertiary hexylperoxy)cyclohexane (half-life temperature of 1 minute: 149.2℃), etc. Among them, in terms of excellent crosslinking reaction efficiency, examples include di(4-tert-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1°C), dilauryl peroxide (1 minute half-life temperature: 116.4°C), and dibenzoyl peroxide (1 minute half-life temperature: 130.0°C).

The half-life of peroxide is an indicator of the decomposition rate of peroxide, which means the time until the residual amount of peroxide becomes half. The decomposition temperature used to reach the half-life within a certain time, or the half-life time at a certain temperature, is recorded in the manufacturer's catalog, such as the "Organic Peroxide Catalog 9th Edition (May 2003)" of NOF Corporation.

When a crosslinking agent is blended into the adhesive composition, the blending amount of the crosslinking agent is preferably 0.01 to 3 parts by weight, preferably 0.02 to 2 parts by weight, and more preferably 0.03 to 1 part by weight relative to 100 parts by weight of the base polymer. When the blending amount of the crosslinking agent is more than 0.01 parts by weight, the adhesive layer 1 will be fully crosslinked and tend to have improved durability or adhesive properties. On the other hand, when the blending amount of the crosslinking agent is less than 3 parts by weight, the adhesive layer 1 will become hard and tend to suppress the decrease in durability.

When an isocyanate crosslinking agent is blended into the adhesive composition, the blending amount of the isocyanate crosslinking agent is preferably 0.01 to 2 parts by weight, preferably 0.02 to 2 parts by weight, and more preferably 0.05 to 1.5 parts by weight relative to 100 parts by weight of the base polymer. When the blending amount of the isocyanate crosslinking agent is within the above range, the cohesive force of the adhesive layer 1 will be enhanced and the tendency to peel off in the durability test will be suppressed.

When peroxide is mixed in the adhesive composition, the amount of peroxide mixed is preferably 0.01 to 2 parts by weight, preferably 0.04 to 1.5 parts by weight, and more preferably 0.05 to 1 part by weight relative to 100 parts by weight of the base polymer. When the amount of peroxide mixed is within the above range, the processability, crosslinking stability, etc. of the adhesive layer 1 can be easily adjusted.

<Other ingredients>

The adhesive composition may further contain an ionic compound. There is no particular limitation on the ionic compound, and those used in the field may be used appropriately. Examples of the ionic compound include those described in Japanese Patent Publication No. 2015-4861, among which (perfluoroalkylsulfonyl)imide lithium salt is preferred, and bis(trifluoromethanesulfonylimide) lithium is more preferred. There is no particular limitation on the amount of the ionic compound blended, and it may be set within a range that does not impair the effect of the invention, for example, relative to 100 parts by weight of the base polymer, it is preferably 10 parts by weight or less, preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and particularly preferably 1 part by weight or less.

The adhesive composition may also contain other known additives, such as colorants, pigment powders, dyes, surfactants, plasticizers, adhesives, surface lubricants, levelers, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, foils, etc., according to the application. Furthermore, a redox system with a reducing agent added may be used within a controllable range. Such additives are preferably used in an amount of less than 5 parts by weight, further less than 3 parts by weight, and further less than 1 part by weight relative to 100 parts by weight of the base polymer.

<Manufacturing method of adhesive layer>

When the adhesive layer 1 is formed from the adhesive composition, it is advisable to adjust the overall amount of the crosslinking agent added relative to the adhesive composition, while fully considering the effect of the crosslinking treatment temperature or crosslinking treatment time.

Depending on the crosslinking agent used, the crosslinking treatment temperature or crosslinking treatment time can be appropriately adjusted. The crosslinking treatment temperature is preferably below 170°C. The crosslinking treatment can be performed at the temperature of the adhesive layer 1 during the drying step, or a crosslinking treatment step can be set after the drying step. The crosslinking treatment time can be set in consideration of productivity or workability, usually about 0.2 to 20 minutes, preferably about 0.5 to 10 minutes.

The method for forming the adhesive layer 1 is not particularly limited, and may be the following method: applying an adhesive composition on various substrates, and drying it in a dryer such as a hot oven to volatilize the solvent, and performing a crosslinking treatment as needed to form the adhesive layer 1, and transferring the adhesive layer 1 to the polarizing film 2; or directly applying the adhesive composition on the polarizing film 2 to form the adhesive layer 1.

There is no particular limitation on the substrate, and examples thereof include various substrates such as release films and transparent resin film substrates.

Various methods can be used to apply the adhesive composition to the substrate or polarizing film 2. Specifically, for example, there can be cited: injection coating machine, roller coating, contact roller coating, gravure coating, reverse coating, roller brush, spray coating, dip roller coating, rod coating, scraper coating, air knife coating, curtain coating, die lip coating, extrusion coating using a die coating machine, etc.

The above drying conditions (temperature, time) are not particularly limited and can be appropriately set according to the composition and concentration of the adhesive composition, for example, about 80~170℃, preferably 90~200℃, and 1~60 minutes, preferably 2~30 minutes. After drying, crosslinking treatment can be performed as needed, and the conditions are as mentioned above.

The thickness of the adhesive layer 1 (after drying) is preferably 5 to 100 μm, preferably 7 to 70 μm, and more preferably 10 to 50 μm. If the thickness of the adhesive layer 1 is above 5 μm, the adhesion to the adherend will be improved and it tends to have sufficient durability under humidified conditions. On the other hand, when the thickness of the adhesive layer is below 100 μm, the adhesive composition can be dried sufficiently when forming the adhesive layer 1, which can suppress the remaining bubbles or uneven thickness of the adhesive layer 1, and it tends to be less likely to cause appearance problems.

The constituent materials of the release film include, for example, resin films such as polyethylene, polypropylene, polyethylene terephthalate, polyester film, porous materials such as paper, cloth, non-woven fabric, mesh, foam sheet, metal foil, and laminates thereof. From the perspective of excellent surface smoothness, the release film is suitable for using resin film. Examples of the resin film include, for example, polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

The thickness of the release film is usually 5~200μm, preferably about 5~100μm. If necessary, the release film can also be subjected to release treatment and anti-fouling treatment using release agents such as polysiloxane, fluorine, long-chain alkyl, fatty acid amide, silicon powder, etc., or anti-static treatment such as coating, kneading, and evaporation. In particular, by appropriately performing a release treatment such as polysiloxane treatment, long-chain alkyl treatment, and fluorine treatment on the surface of the release film, the release property of the self-adhesive layer 1 can be further improved.

There is no particular limitation on the transparent resin film substrate, and various transparent resin films can be used. The resin film is formed by one layer of film. For example, the material can include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyether sulfide resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, polyphenylene sulfide resins, etc. Among them, polyester resins, polyimide resins and polyether sulfide resins are particularly desirable. The thickness of the film substrate should be 15~200μm.

[Polarizing film]

The polarizing film 2 is a laminate containing a polarizer and a transparent protective film. The transparent protective film is arranged, for example, in contact with the main surface (surface with the largest area) of the layered polarizer. The polarizer can also be arranged between two transparent protective films.

There is no special restriction on the polarizer, and various polarizers can be used. Examples of polarizers include: hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified films of ethylene-vinyl acetate copolymers adsorbing dichroic substances such as iodine or dichroic dyes and uniaxially stretched; polyolefin-based oriented films such as dehydrated polyvinyl alcohol and dehydrogenated polyvinyl chloride. Among them, the polarizer composed of polyvinyl alcohol films and dichroic substances such as iodine is preferred, and the iodine-based polarizer containing iodine and/or iodine ions is more preferred. There is no special restriction on the thickness of the polarizer, which is generally about 5~80μm.

If it is a polyvinyl alcohol film, in a high temperature environment, polyvinyl alcohol will be polyene-degraded due to dehydration reaction, thereby reducing the optical properties of the film. Polyene-degradation tends to occur significantly when the water content of the polarizing film 2 is high. Therefore, when the polarizing element uses a polyvinyl alcohol film, preheating to reduce the water content of the polarizing film 2 in advance is particularly important.

The polarizer of the polyvinyl alcohol film dyed with iodine and uniaxially stretched can be made as follows: dyeing is performed by immersing the polyvinyl alcohol in an iodine aqueous solution and stretching it to 3 to 7 times the original length. If necessary, the polyvinyl alcohol can also be immersed in an aqueous solution of potassium iodide containing boric acid, zinc sulfate, zinc chloride, etc. If necessary, the polyvinyl alcohol film can be immersed in water and washed before dyeing. By washing the polyvinyl alcohol film with water, the dirt or anti-caking agent on the surface of the polyvinyl alcohol film can be washed away. In addition, it also has the effect of swelling the polyvinyl alcohol film and thus suppressing the occurrence of uneven dyeing. The stretching of the polyvinyl alcohol film can be performed after dyeing with iodine, while dyeing, or before dyeing with iodine. The stretching can be performed in an aqueous solution or water bath of boric acid, potassium iodide, etc.

The polarizer may also be a thin polarizer with a thickness of less than 10μm. From the perspective of thinness, the thickness of the polarizer is preferably 1~7μm. Such a thin polarizer has less uneven thickness, excellent visibility and less dimensional change, so it has excellent durability. Furthermore, it is more ideal in terms of seeking to thin the polarizing film 2.

Representative examples of thin polarizers include thin polarizing films described in Japanese Patent Publication No. 51-069644, Japanese Patent Publication No. 2000-338329, International Publication No. 2010/100917, Japanese Patent Publication No. 4751481, and Japanese Patent Publication No. 2012-073563. These thin polarizing films can be produced by a method comprising the following steps: a step of extending a polyvinyl alcohol resin (hereinafter, also referred to as a PVA resin) layer and an extending resin substrate in a laminated state; and a dyeing step. According to this manufacturing method, since the PVA resin layer is supported by the stretching resin substrate, even if the PVA resin layer is thin, defects such as breakage caused by stretching can be suppressed.

In the method including the step of stretching in a laminate state and the step of dyeing, from the viewpoint of being able to stretch to a high ratio and improving polarization performance, the method described in International Publication No. 2010/100917, Japanese Patent No. 4751481, and Japanese Patent Publication No. 2012-073563 is preferred, and the method includes the step of stretching in a boric acid aqueous solution, and in particular, the method described in Japanese Patent No. 4751481 or Japanese Patent Publication No. 2012-073563 is preferred, and the method includes the step of auxiliary air stretching before stretching in a boric acid aqueous solution.

The material for forming the transparent protective film disposed on one or both sides of the polarizer may be, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. Specific examples of such thermoplastic resins include cellulose resins such as cellulose triacetate, polyester resins, polyether sulphate resins, polysulphate resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material of the transparent protective film may also be a thermosetting resin or UV-curing resin such as (meth) acrylic acid, urethane, acrylic urethane, epoxy, or silicone. When the polarizing film 2 has two transparent protective films, the materials of the two transparent protective films may be the same or different. For example, a transparent protective film made of a thermoplastic resin may be attached to one main surface of the polarizer through an adhesive, and a transparent protective film made of a thermosetting resin or UV-curing resin may be attached to the other main surface of the polarizer. The transparent protective film may contain one or more arbitrary additives. Additives include, for example, ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, coloring agents, etc. The content of thermoplastic resin in the transparent protective film is preferably 50-100% by weight, preferably 50-99% by weight, more preferably 60-98% by weight, and particularly preferably 70-97% by weight. When the content of thermoplastic resin in the transparent protective film is above 50% by weight, the original high transparency of the thermoplastic resin tends to be fully manifested.

The thickness of the transparent protective film can be appropriately determined. Generally, it is about 10~200μm from the perspective of workability such as strength or handling, and film properties.

The moisture permeability of at least one transparent protective film contained in the polarizing film 2 is preferably 300 g/m ² . 24 h or more, preferably 500 g/m ^{2 .} 24 h or more, and more preferably 800 g/m ² . 24 h or more. When the moisture permeability of the transparent protective film is high, the moisture content of the polarizing film 2 can be easily reduced by preheating. On the other hand, if the moisture permeability of the transparent protective film is too high, the humidification durability of the polarizing film 2 will be reduced. Therefore, the moisture permeability of the transparent protective film is preferably 1600 g/m ² . 24 h or less, and more preferably 1300 g/m ² . 24 h or less. In addition, moisture permeability is the value measured according to the moisture permeability test (cup method) of JIS Z0208, and is the weight of water vapor that passes through a sample area of ^1m2 within 24 hours at 40℃ and a relative humidity difference of 90%.

Polarizers and transparent protective films are usually adhered to each other through water-based adhesives. Examples of water-based adhesives include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex adhesives, water-based polyurethane, and water-based polyester. Other adhesives other than the above adhesives include UV-curable adhesives and electron beam-curable adhesives. Electron beam-curable polarizing film adhesives show appropriate adhesion to various transparent protective films. Adhesives may also contain metal compound fillers.

In the polarizing film 2, a phase difference film can also be formed on the polarizing element to replace the transparent protective film. Other transparent protective films or phase difference films can also be further provided on the transparent protective film.

For the transparent protective film, a hard coating layer can be provided on the surface opposite to the surface connected to the polarizer, and treatments for the purpose of anti-reflection, anti-adhesion, diffusion, anti-glare, etc. can also be performed.

[Other components]

The polarizing film 10 with an adhesive layer may also have other optical films other than the polarizing film 2. Other optical films include reflective plates, reflective plates, phase difference films, viewing angle compensation films, brightness enhancement films, and other films used in liquid crystal display devices. Phase difference films include, for example, 1/2 wavelength plates, 1/4 wavelength plates, and the like. The polarizing film 10 with an adhesive layer may also have one or more of these other optical films.

The polarizing film 10 with an adhesive layer may further include an anchoring layer between the polarizing film 2 and the adhesive layer 1. The material forming the anchoring layer is not particularly limited, and examples thereof include various polymers, metal oxide sols, silica sols, etc. Among these, polymers are particularly suitable. The polymers may be used in any of the solvent-soluble, water-dispersible, and water-soluble forms.

Examples of the above-mentioned polymers include polyurethane resins, polyester resins, acrylic resins, polyether resins, cellulose resins, polyvinyl alcohol resins, polyvinyl pyrrolidone, polystyrene resins, etc.

When the adhesive layer 1 of the polarizing film 10 with an adhesive layer is exposed, a release film (separation film) can be used to protect the adhesive layer 1 until it is actually used. The release film can be exemplified by the aforementioned material. When making the adhesive layer 1, when the release film is used as a substrate, by laminating the adhesive layer 1 on the release film and the polarizing film 2, the release film can be used as the release film of the adhesive layer 1 of the polarizing film 10 with an adhesive layer, which can simplify the steps.

[Characteristics of the adhesive layer]

The adhesive layer 1 of the polarizing film 10 with an adhesive layer can maintain the reworkability after preheating even when attached to the conductive layer, and has durability in a high temperature environment. Next, the reason and the thinking mechanism are explained.

After the adhesive layer 1 is formed from the adhesive composition, the anhydride groups of the compound (C) in the adhesive layer 1 are hydrolyzed by the moisture in the air and are converted into acid groups. On the other hand, on the surface of the conductive layer containing metal oxides such as ITO, there are not only hydroxyl groups but also metal cations generated by the hydroxyl groups being released in the form of hydroxyl ions. As shown in FIG2 , when the polarizing film 10 with the adhesive layer attached is attached to the conductive layer 3 using the adhesive layer 1, the acid groups of the compound (C) are deprotonated by neutralization reaction with the hydroxyl ions existing near the surface of the conductive layer 3. The anions thus generated form ionic bonds with the metal cations on the surface of the conductive layer 3. That is, an acid-base reaction occurs between the acid group of the compound (C) and the conductive layer 3. It can be inferred that the compound (C) is segregated on the surface of the conductive layer 3, and the first layer 11 containing the compound (C) can be formed in the adhesive layer 1.

After the first layer 11 is formed, the polyether compound (D) tends to segregate on the surface of the first layer 11. Therefore, in the adhesive layer 1, the second layer 12 containing the polyether compound (D) can be formed on the first layer 11. In addition, when the adhesive layer 1 does not contain the compound (C), the polyether compound (D) hardly segregates on the surface of the conductive layer 3. Therefore, the first layer 11 can be regarded as a surface modification layer that modifies the surface of the conductive layer 3 and makes the polyether compound (D) easily segregate.

Thus, it can be inferred that by using the adhesive layer 1 to bond the polarizing film 10 with the adhesive layer to the conductive layer 3, the first layer 11 and the second layer 12 can be formed in the adhesive layer 1. By forming the first layer 11 and the second layer 12, the third layer 13 mainly containing the adhesive can be further formed in the adhesive layer 1. The first layer 11, the second layer 12, and the third layer 13 are arranged in order in the stacking direction.

Before preheating, the cohesion of the first layer 11 and the second layer 12 is smaller than that of the third layer 13. Therefore, before preheating, the polarizing film 10 with the adhesive layer can be easily peeled off from the conductive layer 3 by destroying the cohesion of the first layer 11 or the second layer 12.

When preheating is performed at a temperature of about 70°C to 95°C, for example, the cohesive force of the first layer 11 tends to increase significantly due to the reaction of the compound (C). The increase in the cohesive force of the first layer 11 is particularly significant when the compound (C) contains a hydrolyzable group (h1). On the other hand, the cohesive force of the second layer 12 is less likely to increase than that of the first layer 11. Therefore, after preheating, the polarizing film 10 with the adhesive layer can be easily peeled off from the conductive layer 3 by destroying the cohesion at the second layer 12 or at the interface between the first layer 11 and the second layer 12. That is, the second layer 12 functions as a layer that ensures the heavy workability of the adhesive layer 1 after preheating.

Furthermore, when the adhesive layer 1 is placed in an environment with a temperature higher than 95°C, the cohesive force of the second layer 12 tends to be greatly increased due to the reaction of the polyether compound (D). The increase in the cohesive force of the second layer 12 is particularly significant when the polyether compound (D) contains a hydrolyzable group (h2). As a result, the adhesion between the adhesive layer 1 and the conductive layer 3 is greatly increased, and the durability of the adhesive layer 1 tends to be improved.

From another aspect, the present invention provides an adhesive layer 1, which is formed by an adhesive composition, and the adhesive composition contains a compound (C) having an acid group or anhydride group and a polyether compound (D), and the adhesion force _P85 obtained by test 1 is less than 10.0N/25mm, and the adhesion force _P105 obtained by test 2 is greater than 10.0N/25mm.

(Implementation form of image display panel)

As shown in FIG3 , the image display panel 100 of the present embodiment has a polarizing film 10 with an adhesive layer, a conductive layer 3, and a transparent substrate 4. The conductive layer 3 and the transparent substrate 4 are components constituting the liquid crystal unit 20, for example. That is, the image display panel 100 is a liquid crystal display panel having the polarizing film 10 with an adhesive layer and the liquid crystal unit 20. However, the image display panel 100 may also have an organic EL unit instead of the liquid crystal unit 20. In the image display panel 100, the polarizing film 10 with an adhesive layer is, for example, located closer to the viewing side than the liquid crystal unit 20.

The polarizing film 10 with an adhesive layer, the conductive layer 3 and the transparent substrate 4 are arranged in sequence in the stacking direction, and the adhesive layer 1 of the polarizing film 10 with an adhesive layer is directly connected to the conductive layer 3. In other words, the polarizing film 10 with an adhesive layer is attached to the conductive layer 3 by the adhesive layer 1. The conductive layer 3 is directly connected to the transparent substrate 4, for example. Between the conductive layer 3 and the transparent substrate 4, other layers such as a primer layer and an anti-oligomer layer may also be arranged as needed.

[Adhesive layer]

As described above, when the polarizing film 10 with an adhesive layer is bonded to the conductive layer 3 using the adhesive layer 1, the first layer 11, the second layer 12, and the third layer 13 can be formed in the adhesive layer 1. The conductive layer 3, the first layer 11, the second layer 12, and the third layer 13 are arranged in sequence in the stacking direction, and the third layer 13 is located between the second layer 12 and the polarizing film 2.

The first layer 11 contains, for example, a compound (C) or a reactant (R1) thereof. When the compound (C) contains a hydrolyzable group (h1), the reactant (R1) is, for example, a hydrolysis condensate of a plurality of compounds (C), or a reactant of the compound (C) and a hydroxyl group on the surface of the conductive layer 3. The first layer 11 may also contain the compound (C) or a reactant (R1) thereof as a main component.

The second layer 12 contains, for example, a polyether compound (D) or its reactant (R2). When the polyether compound (D) contains a hydrolyzable group (h2), the reactant (R2) is, for example, a hydrolysis condensate of a plurality of polyether compounds (D). The second layer 12 may also contain a polyether compound (D) or its reactant (R2) as a main component.

The third layer 13 contains a base polymer such as a (meth)acrylic polymer (A) or a reactant (R3) thereof. When the adhesive composition forming the adhesive layer 1 contains a crosslinking agent, the reactant (R3) is, for example, a crosslinked product of the (meth)acrylic polymer (A). The third layer 13 may also contain a (meth)acrylic polymer (A) or a reactant (R3) thereof as a main component.

In addition, the adhesive layer 1 has the first layer 11, the second layer 12 and the third layer 13, which can also be confirmed by using methods such as time-of-flight secondary ion mass spectrometry (TOF-SIMS). For example, an adhesive composition for forming the adhesive layer 1 is prepared. The adhesive composition is applied to the conductive layer 3 to form a coating film with a thickness of about 1μm after drying. The film obtained by drying the coating film is analyzed by TOF-SIMS from its surface to the thickness direction of the film. In this way, it can be confirmed that the adhesive layer 1 has the first layer 11, the second layer 12 and the third layer 13.

[Conductive layer]

The conductive layer 3 is not particularly limited as long as it contains metal oxides. Metal oxides may include, for example, oxides containing the following metals: at least one selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium and tungsten. The conductive layer 3 is not only a metal oxide, but may also contain metals shown in the above group as needed. The material of the conductive layer 3 is preferably indium tin oxide, tin oxide containing antimony, etc. Indium tin oxide means indium oxide containing tin oxide, and is also called indium-tin composite oxide or ITO. The conductive layer 3 preferably contains ITO, and is more preferably substantially composed of ITO.

The content of indium oxide in the ITO contained in the conductive layer 3 is preferably 80 to 99% by weight. The content of tin oxide in ITO is preferably 1 to 20% by weight. ITO may be crystalline or non-crystalline (amorphous).

The thickness of the conductive layer 3 is not particularly limited, and is preferably greater than 10 nm, preferably 15 to 40 nm, and more preferably 20 to 30 nm.

There is no special restriction on the method for forming the conductive layer 3, and a conventionally known method can be used. Specifically, the conductive layer 3 can be made by vacuum evaporation, sputtering, ion plating, etc. These methods can be appropriately selected according to the required film thickness of the conductive layer 3.

[Transparent substrate]

The transparent substrate 4 can be any transparent substrate, and its material is not particularly limited. The transparent substrate 4 can be, for example, glass or a transparent resin film substrate. The transparent resin film substrate can be, for example, the above-mentioned ones.

[Liquid crystal unit]

For example, the liquid crystal unit 20 has a liquid crystal layer 5 and a transparent substrate 6 in addition to the conductive layer 3 and the transparent substrate 4. In the liquid crystal unit 20, the conductive layer 3, the transparent substrate 4, the liquid crystal layer 5 and the transparent substrate 6 are arranged in sequence in the stacking direction.

There is no special restriction on the liquid crystal layer 5, for example, TN type, STN type, π type, VA type, IPS type, etc. can be used arbitrarily. The transparent substrate 6 can be any transparent substrate, and its material is not particularly limited. The transparent substrate 6 can be, for example, glass or a transparent resin film substrate. The transparent resin film substrate can be, for example, the above-mentioned substances.

[Other components]

In addition to the polarizing film 10 with an adhesive layer and the liquid crystal unit 20, the image display panel 100 may also have optical films such as phase difference film, viewing angle compensation film, and brightness enhancement film.

[Manufacturing method of image display panel]

The manufacturing method of the image display panel 100 is not particularly limited, and for example includes: after the polarizing film 10 with the adhesive layer is attached to the conductive layer 3, the adhesive layer 1 is subjected to a first heating treatment at 70°C to 95°C.

The first heat treatment is equivalent to preheating for reducing the moisture content of the polarizing film 2. The temperature of the first heat treatment is preferably 80°C to 95°C. The time of the first heat treatment is not particularly limited, for example, 1 hour to 5 hours, preferably 3 hours to 5 hours.

The moisture content of the polarizing film 2 after the first heat treatment is not particularly limited, and is, for example, 7 g/m ² or less. The moisture content of the polarizing film 2 can be measured using the method described in Patent Document 1.

The manufacturing method of the image display panel 100 may further include: after the first heat treatment, performing a second heat treatment on the adhesive layer 1 at a temperature higher than 95°C. Through the second heat treatment, the adhesion of the adhesive layer 1 is greatly increased, and the durability of the adhesive layer 1 tends to be improved. The temperature of the second heat treatment may be 100°C to 150°C. There is no special limitation on the time of the second heat treatment, for example, 1 hour to 1000 hours, preferably more than 24 hours.

(Variation example of image display panel)

The image display panel 100 may also have two polarizing films 10 with adhesive layers. As shown in FIG. 4 , the image display panel 110 of this variant has two polarizing films 10a and 10b with adhesive layers. Except for the polarizing film 10b with adhesive layers, the structure of the image display panel 110 is the same as that of the image display panel 100. Therefore, the common elements in the image display panel 100 and the image display panel 110 of the variant are attached with the same reference symbols, and their descriptions are sometimes omitted.

The polarizing film 10b with an adhesive layer is attached to the transparent substrate 6 of the liquid crystal unit 20 by using the adhesive layer 1b. In the image display panel 110, the liquid crystal unit 20 is located between the polarizing films 10a and 10b with an adhesive layer, and is located closer to the viewing side than the polarizing film 10b with an adhesive layer.

The adhesive layer 1b and polarizing film 2b of the polarizing film 10b with an adhesive layer may be the same as or different from the adhesive layer 1a and polarizing film 2a of the polarizing film 10a with an adhesive layer. The adhesive layer 1b and polarizing film 2b may also be those used in the art in the past.

(Implementation form of image display device)

The image display device of this embodiment, for example, has an image display panel 100 and a lighting system. The image display panel 110 can also be used in the image display device to replace the image display panel 100. In the image display device, the image display panel 100 is, for example, arranged closer to the visual recognition side than the lighting system. The lighting system, for example, has a backlight source or a reflector, and irradiates light to the image display panel 100.

Image display devices include, for example, liquid crystal display devices, electroluminescent (EL) displays, plasma displays (PD), field emission displays (FED), etc. Such image display devices can be used for home appliances, in-vehicle applications, public information displays (PID), etc., and are particularly ideal for in-vehicle applications.

Implementation example

The present invention is described in more detail below using examples. The present invention is not limited to the examples shown below. In addition, below, unless otherwise stated, "%" means "weight %", "parts" means "weight parts", and "thickness" means "physical film thickness". Unless otherwise stated, the indoor temperature and humidity are 23°C and 65%RH.

(Acrylic polymer (A1))

In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler, a monomer mixture containing 100 parts by weight of butyl acrylate (BA), 0.075 parts by weight of 4-hydroxybutyl acrylate (HBA), and 5 parts by weight of acrylic acid (AA) was injected. Furthermore, 0.1 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) was injected as a polymerization initiator together with 100 parts by weight of ethyl acetate relative to 100 parts by weight of the monomer mixture, and nitrogen was introduced while slowly stirring to replace the nitrogen. The liquid temperature in the flask was maintained at about 55°C, and the polymerization reaction was carried out for 6 hours. In this way, a solution of an acrylic polymer (A1) with a weight average molecular weight of 2.4 million and Mw/Mn=4.5 was prepared.

(Acrylic polymer (A2))

Except for changing the monomers used as shown in Table 1, the solutions of acrylic polymer (A2) were prepared in the same manner as acrylic polymer (A1).

(Acrylic oligomer (B1))

In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler, 85 parts by weight of butyl acrylate (BA), 15 parts by weight of acrylic acid (AA), 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator, 100 parts by weight of toluene, and 3.5 parts by weight of α-thioglycerol were injected. While slowly stirring, nitrogen was introduced to fully replace the nitrogen. The liquid temperature in the flask was maintained at about 60°C, and the polymerization reaction was carried out for 4 hours to prepare a solution of acrylic oligomer (B1). The weight average molecular weight of acrylic oligomer (B1) is 6700.

(Acrylic oligomer (B2))

Except for changing the monomers used as shown in Table 1, the acrylic oligomer (B2) was prepared by the same method as the acrylic oligomer (B1).

The abbreviations in Table 1 are as follows.

BA: n-butyl acrylate

HBA: 4-Hydroxybutyl acrylate

AA: Acrylic acid

PEA: Phenoxyethyl acrylate

NVP: N-vinyl-2-pyrrolidone

MEA: 2-methoxyethyl acrylate

(Compound (C1))

According to the method described in Example 1 of Japanese Patent Publication No. 2013-129809, compound (C1) was prepared. Compound (C1) is an organic polysiloxane compound and contains the above-mentioned siloxane units (U1) and (U2). In the siloxane unit (U1), X is a propyl succinic anhydride group and ^R4 is a methyl group. In the siloxane unit (U2), both ^R4 are methoxy groups. The content of siloxane unit (U1) in compound (C1) is 27 mol%. The content of siloxane unit (U2) in compound (C1) is 73 mol%. The weight average molecular weight of compound (C1) is about 1000.

(Polarizing film)

[TAC film with HC]

First, a resin solution (DIC, trade name: UNIDIC17-806, solid content concentration: 80%) in which a UV-curable resin monomer or oligomer having urethane acrylate as the main component is dissolved in butyl acetate is prepared. Then, 5 parts of a photopolymerization initiator (BASF, trade name: IRGACURE907) and 0.1 parts of a leveling agent (DIC, trade name: GRANDIC PC4100) are added to the resin solution relative to 100 parts of the solid content of the resin solution. Next, cyclopentanone and propylene glycol monomethyl ether are added to the solution at a ratio of 45:55 so that the solid content concentration of the obtained solution reaches 36%, thereby preparing a material for forming a hard coating layer. Next, the material was coated on a TAC film (TJ40UL manufactured by FUJIFILM Corporation, raw material: cellulose triacetate polymer, thickness: 40μm) so that the thickness of the hard coating layer after curing reached 7μm to form a coating. Then, the coating was dried at 90°C for 1 minute, and then a high-pressure mercury lamp was used to irradiate the coating with ultraviolet light with an integrated light intensity of 300mJ/ ^cm2 , thereby curing the coating and forming a hard coating layer (HC). In this way, a TAC film with HC was produced.

[Acrylic film]

Into a 30L autoclave reactor equipped with a stirring device, a temperature sensor, a cooling tube, and a nitrogen inlet tube, 8,000g of methyl methacrylate (MMA), 2,000g of methyl 2-(hydroxymethyl)acrylate (MHMA), 10,000g of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), and 5g of n-dodecyl mercaptan were injected, nitrogen was passed through the reactor, and the temperature was raised to 105°C. At the beginning of reflux, 5.0 g of tertiary butyl peroxyisopropyl carbonate (KAYAKARUBON BIC-7, manufactured by KAYAKU AKZO) was added as a polymerization initiator. At the same time, a solution consisting of 10.0 g of tertiary butyl peroxyisopropyl carbonate and 230 g of MIBK was titrated for 4 hours, and solution polymerization was carried out at about 105-120°C under reflux, and then matured for another 4 hours.

30 g of octadecyl phosphate/dioctadecyl phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Industry) was added to the obtained polymer solution, and a cyclocondensation reaction was carried out at about 90-120°C for 5 hours under reflux. Then, the obtained polymer solution was introduced into a vented twin screw extruder (φ=29.75 mm, L/D=30) with a barrel temperature of 260°C, a rotation speed of 100 rpm, a reduced pressure of 13.3-400 hPa (10-300 mmHg), 1 rear vent hole, and 4 front vent holes at a processing speed of 2.0 kg/h in terms of resin amount. Devolatilization was carried out in the extruder together with the further cyclocondensation reaction. In this way, transparent pellets of polymers containing lactone rings are obtained.

When the obtained lactone ring-containing polymer was subjected to dynamic TG measurement, a mass loss of 0.17 mass % was detected. The weight average molecular weight of the lactone ring-containing polymer was 133,000, the melt flow rate was 6.5 g/10 min, and the glass transition temperature was 131°C.

The pellets were mixed and extruded with acrylonitrile-styrene (AS) resin (TOYO ASAS20, manufactured by Toyo Styrene Co., Ltd.) at a mass ratio of 90/10 using a single-screw extruder (screw 30 mm φ) to produce transparent pellets. The glass transition temperature of the pellets was 127°C.

The pellets were melt-extruded from a 400mm wide coat hanger T-die using a 50mm φ single-axis extruder to produce a 120μm thick film. The film was stretched 2.0 times in length and 2.0 times in width at 150°C using a double-axis stretching device to produce a 30μm thick stretched film (acrylic film). When the optical properties of the stretched film were measured, the total light transmittance was 93%, the in-plane phase difference △nd was 0.8nm, and the thickness direction phase difference Rth was 1.5nm.

Next, a polarizing film was produced using the following method. First, a polyvinyl alcohol film with a thickness of 45 μm was dyed in a 0.3% iodine solution (temperature 30°C) for 1 minute between multiple rollers with different speed ratios, and stretched to a stretching ratio of 3 times. Then, the stretched film was immersed in an aqueous solution of 4% boric acid and 10% potassium iodide (temperature 60°C) for 0.5 minutes, and stretched to a total stretching ratio of 6 times. Then, the stretched film was washed by immersing it in an aqueous solution containing 1.5% potassium iodide (temperature 30°C) for 10 seconds. The stretched film was then dried at 50°C for 4 minutes, thereby producing a polarizing element with a thickness of 18 μm. On one main surface of the polarizer, the saponified HC-attached TAC film is bonded via a polyvinyl alcohol adhesive. At this time, the cellulose triacetate film is located closer to the polarizer side than the hard coating layer. On the other main surface of the polarizer, the acrylic film is bonded via a polyvinyl alcohol adhesive. In this way, a polarizing film is obtained.

(Implementation Example 1)

To 100 parts of the solid content of the solution of the acrylic polymer (A1), 0.4 parts of the blending compound (C1), 0.4 parts of the polyether compound (D) (SILYL SAT10 manufactured by Kaneka Corporation), 0.5 parts of lithium bis(trifluoromethanesulfonyl)imide, 1 part of an isocyanate crosslinking agent (Coronate L manufactured by Tosoh Corporation, trihydroxymethylpropane diisocyanate toluene) and 0.2 parts of benzoyl peroxide (NYPER BMT manufactured by NOF Corporation) were added to prepare a solution of an acrylic adhesive composition. SILYL SAT10 is a compound represented by the above formula (13), wherein ^A1 is _-CH2CH ( _CH3 )-, ^A2 _{is -C3H6-} , ^Z1 is _-C3H6 - _Z0 , ^and the reactive silyl group ( ^Z0- ) is dimethoxymethylsilyl. The number average molecular weight of SILYL SAT10 is 5000.

Next, the prepared acrylic adhesive composition solution was applied to one side of a polyethylene terephthalate film (separation film: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone release agent until the adhesive layer had a thickness of 20 μm after drying. The coated film was dried at 155°C for 1 minute to form an adhesive layer on the surface of the separation film. Next, the adhesive layer formed on the separation film was transferred to the acrylic film side of the polarizing film to produce the polarizing film with an adhesive layer of Example 1.

(Examples 2 to 12, Comparative Examples 1 to 3)

Except for changing the composition of the acrylic adhesive composition as shown in Table 2, the polarizing films with adhesive layers of Examples 2 to 12 and Comparative Examples 1 to 3 were prepared by the same method as Example 1.

[Evaluation]

<Weight average molecular weight (Mw) of acrylic polymers and acrylic oligomers>

The weight average molecular weight (Mw) of the prepared acrylic polymer and acrylic oligomer was measured by GPC (gel permeation chromatography).

．Analysis device: HLC-8120GPC manufactured by TOSOH Corporation

． Column: Made by Tosoh, G7000H _XL +GMH _XL +GMH _XL

．Column size: 7.8mm φ×30cm each, 90cm in total

．Column temperature: 40℃

．Flow rate: 0.8ml/min

．Injection volume: 100μl

． Solvent: Tetrahydrofuran

．Detector: Differential Refractometer (RI)

． Standard sample: polystyrene

<Continue>

The adhesion of the adhesive layer obtained is P ₀ , P ₈₅ and P ₁₀₅ , which are implemented by the above-mentioned tests 1 to 3. The glass with ITO layer is produced by forming an ITO layer on an alkali-free glass with a thickness of 7 mm (manufactured by Corning, trade name "EG-XG"). The ITO layer is produced by sputtering. In the ITO layer, the ratio of the weight of Sn atoms to the total weight of Sn atoms and In atoms (Sn ratio) is 3 wt%. The surface of the ITO layer is analyzed under the following measurement conditions using an atomic force microscope (AFM, manufactured by Bruker, Dimension 3100+Nanoscope V). As a result, the average surface roughness Ra of the ITO layer was 0.2 nm, the root mean square roughness Rq was 0.3 nm, and the maximum height Rmax was 2.6 nm. The operation of peeling the test piece from the ITO layer was performed using a tensile testing machine (Autograph SHIMAZU AG-1 10KN).

(AFM measurement conditions)

．Measurement mode: tapping mode

．Cantilever: Si single crystal

．Measurement area: 10μm square

<Initial reworkability>

The glass with ITO layer used for measuring adhesion strength is subjected to a rework test using the following method. First, a thin rectangular shape of 230mm long and 120mm wide is cut from the polarizing film with adhesive layer to make a test piece. Then, the test piece is bonded to the surface of the ITO layer of the glass with ITO layer using the adhesive layer. The bonding of the test piece to the ITO layer is performed using a lamination machine. After the test piece has been bonded, it is placed in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes to homogenize the bond between the ITO layer and the adhesive layer and to allow the adhesive layer to adhere closely to the ITO layer. Then, the test piece is peeled off from the glass with ITO layer by hand. Repeat the rework test 3 times in the above sequence, and use the following criteria to evaluate the initial reworkability of the adhesive layer.

(Evaluation criteria)

A: All three tablets have no paste residue or film breakage and can be peeled off easily.

B: The film of one of the three pieces was broken due to peeling, but it can be peeled off by peeling again.

C: The film of all three pieces was broken due to peeling, but it can be peeled off by peeling again.

D: There is paste residue on all three pieces, or the film breaks after several attempts to peel it off and cannot be peeled off.

<Heavy workability after preheating>

In the rework test, the ITO layer and the adhesive layer were homogenized in an autoclave, and then heated for 5 hours in an atmospheric pressure environment at 85°C. After the heating treatment, the test piece was placed in an ambient air at room temperature to lower the temperature of the test piece to room temperature. In addition, the reworkability of the adhesive layer after preheating was evaluated using the same method as the above reworkability evaluation.

<Durability>

The glass with ITO layer used for measuring adhesion was subjected to durability test using the following method. First, the polarizing film with adhesive layer was cut into a thin rectangular shape of 300mm long and 220mm wide to make a test piece. Then, the test piece was bonded to the ITO layer surface of the glass with ITO layer using the adhesive layer. The bonding of the test piece to the ITO layer was performed using a lamination machine. After the test piece was bonded, it was placed in an autoclave at 50℃ and 0.5MPa for 15 minutes to homogenize the bonding between the ITO layer and the adhesive layer and to make the adhesive layer closely adhere to the ITO layer. Next, the test piece was heat treated for 500 hours in an atmospheric pressure environment at 105°C. The appearance of the adhesive layer between the polarizing film and the ITO layer was visually observed, and the durability of the adhesive layer was evaluated using the following criteria.

(Evaluation criteria)

A: There is absolutely no change in appearance such as foaming or peeling.

B: There is peeling or foaming at the end, but unless it is used for special purposes, it is not a practical problem.

C: There is obvious peeling at the end, which is problematic for practical use.

The abbreviations in Table 2 are as follows.

A1: Acrylic polymer (A1)

A2: Acrylic polymer (A2)

B1: Acrylic oligomer (B1)

B2: Acrylic oligomer (B2)

C1: Compound (C1)

X-12-967C: 3-Trimethoxysilylpropyl succinic anhydride (manufactured by Shin-Etsu Chemical Co., Ltd.)

SAT10: SILYL SAT10 (manufactured by KANEKA)

X-41-1056: Epoxy-containing oligomer-type silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.)

As can be seen from Table 2, the adhesive layer of the polarizing film with an adhesive layer of this embodiment can maintain the reworkability after preheating even when attached to the conductive layer, and has durability in a high temperature environment. In addition, in Comparative Examples 2 and 3 where the compound (C) does not exist, it can be inferred that under the conditions of measuring the adhesion force P ₀ and P ₈₅ , the SILYL SAT10 of the polyether compound (D) is almost not segregated on the surface of the ITO layer. On the other hand, under the conditions of measuring the adhesion force P ₁₀₅ , SILYL SAT10 is segregated on the surface of the ITO layer. Based on this, it is believed that in Comparative Examples 2 and 3, the adhesion force P ₁₀₅ is lower than the adhesion force P ₈₅ , and as a result, the durability after the heat treatment at 105°C is low.

Industrial availability

The polarizing film with adhesive layer of the present invention can be appropriately used in image display devices such as liquid crystal display devices, electroluminescent (EL) displays, plasma displays (PD), field emission displays (FED), etc.

1: Adhesive layer

2:Polarizing film

10: Polarizing film with adhesive layer

Claims (18)

A polarizing film with an adhesive layer comprises a polarizing film and an adhesive layer formed of an adhesive composition, wherein the adhesive composition contains a base polymer, a compound (C) having an acid group or anhydride group, and a polyether compound (D). In the adhesive composition, the content of the compound (C) is 0.4 parts by weight or more relative to 100 parts by weight of the base polymer. For the adhesive layer, the adhesion force P ₈₅ obtained by the following test 1 is less than 10.0 N/25 mm, and the adhesion force P ₁₀₅ obtained by the following test 2 is greater than 10.0 N/25 mm: Test 1: The adhesive layer on the indium tin layer attached to the indium tin layer was heat treated at 85°C for 5 hours; the force required to peel the adhesive layer from the indium tin layer at a peeling speed of 300 mm/min and a peeling angle of 90° was measured (bonding force P ₈₅ ); Test 2: The adhesive layer on the indium tin layer bonded to the indium tin layer was heat treated at 105°C for 24 hours; the force required to peel the adhesive layer from the indium tin layer at a peeling speed of 300 mm/min and a peeling angle of 90° was measured (bonding force P ₁₀₅ ). A polarizing film with an adhesive layer as claimed in claim 1, wherein the adhesion force _P0 of the adhesive layer is less than 10.0 N/25 mm as determined by the following test 3: Test 3: At a peeling speed of 300 mm/min and a peeling angle of 90°, the adhesive layer on the indium oxide tin layer adhered to the glass with an indium oxide tin layer is peeled off from the indium oxide tin layer; the force required at this time (adhesion force _P0 ) is measured. In the polarizing film with an adhesive layer as claimed in claim 1 or 2, the weight average molecular weight of the compound (C) and the number average molecular weight of the polyether compound (D) are both less than 10,000. The polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the acid anhydride group is a carboxylic acid anhydride group. The polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the compound (C) further comprises a silicon atom and a hydrolyzable group bonded to the silicon atom. In the polarizing film with an adhesive layer as claimed in claim 5, the content of the hydrolyzable group in the compound (C) is greater than 10 wt %. The polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the compound (C) has a siloxane bond. The polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the polyether compound (D) further has a silicon atom and a hydrolyzable group bonded to the silicon atom. The polarizing film with an adhesive layer as claimed in claim 8, wherein the content of the hydrolyzable group in the polyether compound (D) is less than 14 wt %. The polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the adhesive composition contains a (meth)acrylic polymer (A) as the base polymer. The polarizing film with an adhesive layer as claimed in claim 10, wherein the (meth)acrylic polymer (A) has an acid group. An image display panel comprising: A polarizing film with an adhesive layer as in any one of claims 1 to 11; A conductive layer containing a metal oxide; and A transparent substrate; The adhesive layer is directly connected to the conductive layer. An image display panel as claimed in claim 12, wherein the metal oxide contains indium tin oxide. The image display panel of claim 12 or 13, wherein the adhesive layer comprises: A first layer containing the compound (C) or its reactant; and A second layer containing the polyether compound (D) or its reactant; The conductive layer, the first layer and the second layer are arranged in sequence in the stacking direction. As for the image display panel of claim 14, the adhesive layer further has a third layer, the third layer contains a (meth)acrylic polymer (A) or its reactant, and the third layer is located between the second layer and the polarizing film. A method for manufacturing an image display panel is a method for manufacturing an image display panel as in any one of claims 12 to 15, comprising: After the polarizing film with the adhesive layer is attached to the conductive layer, the adhesive layer is subjected to a first heating treatment at 70°C to 95°C. The manufacturing method of the image display panel of claim 16 further comprises: after the first heat treatment, performing a second heat treatment on the adhesive layer at a temperature higher than 95°C. An adhesive layer is formed by an adhesive composition, wherein the adhesive composition contains a base polymer, a compound (C) having an acid group or anhydride group, and a polyether compound (D). In the adhesive composition, the content of the compound (C) is 0.4 parts by weight or more relative to 100 parts by weight of the base polymer. The adhesion force P ₈₅ obtained by the following test 1 is less than 10.0 N/25 mm, and the adhesion force P ₁₀₅ obtained by the following test 2 is greater than 10.0 N/25 mm: Test 1: The adhesive layer on the indium tin layer attached to the indium tin layer was heat treated at 85°C for 5 hours; the force required to peel the adhesive layer from the indium tin layer at a peeling speed of 300 mm/min and a peeling angle of 90° was measured (bonding force P ₈₅ ); Test 2: The adhesive layer on the indium tin layer bonded to the indium tin layer was heat treated at 105°C for 24 hours; the force required to peel the adhesive layer from the indium tin layer at a peeling speed of 300 mm/min and a peeling angle of 90° was measured (bonding force P ₁₀₅ ).

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