Adhesive layer, adhesive film, liquid crystal panel, and organic EL panel

Abstract

The present invention provides an adhesive layer, adhesive film, liquid crystal panel, and organic EL panel that can maintain high performance even when the thickness of the adhesive layer is 15 μm or less. [Solution] An adhesive layer 10 for bonding a polarizing plate 11 and a panel 12, wherein the thickness of the adhesive layer 10 is 1 to 15 μm, and after bonding the polarizing plate to the panel via an adhesive layer with a thickness of 10 μm and undergoing durability tests at 80°C × 500h, 85°C × 85%RH × 500h, and 105°C × 500h, there is no peeling or foaming between the polarizing plate and the adhesive layer with a thickness of 10 μm, and after aging is completed with the adhesive layer with a thickness of 10 μm bonded to the polarizing plate, the adhesive strength after 20 minutes with the adhesive layer with a thickness of 10 μm bonded to alkali-free glass is 5.0 N / 25 mm or less, and the adhesive strength after 10 days at 23°C with the adhesive layer bonded to alkali-free glass is 10 N / 25 mm or less.

Description

[Technical Field]

[0001] The present invention relates to an adhesive layer, an adhesive film, a liquid crystal panel, and an organic EL panel. [Background technology]

[0002] Adhesive films are used in bonding optical components such as polarizing plates, as well as in the assembly and processing of components in electronic devices such as liquid crystal panels and organic EL panels. For example, Patent Document 1 describes using an adhesive layer formed by crosslinking an adhesive composition for bonding optical components such as polarizing plates. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5422629 [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventional technology maintained high performance with an adhesive layer thickness of 20-25 μm, but recent demands for volume reduction and thinner films necessitate thinner adhesive layers. However, actually thinning the adhesive layer makes it difficult to maintain the performance achieved previously.

[0005] The present invention has been made in view of the above circumstances, and aims to provide an adhesive layer, an adhesive film, a liquid crystal panel, and an organic EL panel that can maintain high performance even when the thickness of the adhesive layer is 15 μm or less. [Means for solving the problem]

[0006] The present invention includes the following embodiments. [1] An adhesive layer for bonding a polarizing plate and a panel, wherein the thickness of the adhesive layer is 1 to 15 μm, and after bonding a polarizing plate to a panel via an adhesive layer with a thickness of 10 μm and undergoing a durability test at 80°C × 500 h, there is no peeling or foaming between the polarizing plate and the adhesive layer with a thickness of 10 μm, and after bonding a polarizing plate to a panel via an adhesive layer with a thickness of 10 μm and undergoing a durability test at 85°C × 85% RH × 500 h, there is no peeling or foaming between the polarizing plate and the adhesive layer with a thickness of 10 μm, and a polarizing plate is bonded to a panel via an adhesive layer with a thickness of 10 μm An adhesive layer characterized in that, even after bonding and undergoing a durability test at 105°C for 500 hours, there is no peeling or foaming between the polarizing plate and the adhesive layer having a thickness of 10 μm, the adhesive strength after 20 minutes of bonding the adhesive layer having a thickness of 10 μm to alkali-free glass after aging is completed with the adhesive layer having a thickness of 10 μm to the polarizing plate is 5.0 N / 25 mm or less, and the adhesive strength after 10 days at 23°C with the adhesive layer having a thickness of 10 μm to the alkali-free glass after aging is completed with the adhesive layer having a thickness of 10 μm to the polarizing plate is 10 N / 25 mm or less.

[0007] [2] The adhesive layer is an adhesive layer obtained by crosslinking an adhesive composition comprising an acrylic polymer and (D) a crosslinking agent, wherein the acrylic polymer is a copolymer obtained by copolymerizing (A) at least one alkyl (meth)acrylate monomer having C1 to C18 C atoms in the alkyl group, (B) at least one hydroxyl group-containing copolymerizable vinyl monomer, and (C) at least one selected from the group consisting of alkoxy group-containing vinyl monomer and nitrogen-containing vinyl monomer, and the weight-average molecular weight of the acrylic polymer is 1.5 million to 3.5 million. The acrylic polymer does not contain carboxyl group-containing copolymerizable vinyl monomers, the acid value of the acrylic polymer is 0.1 or less, and of the total 100 parts by mass of the acrylic polymer, the (A) alkyl (meth)acrylate monomer having C1 to C18 carbon atoms in the alkyl group contains at least 50 parts by mass of butyl acrylate, and the (C) at least one selected from the group consisting of alkoxy group-containing vinyl monomers and nitrogen-containing vinyl monomers is 10 parts by mass or more, and the (A) alkyl group has carbon The ratio ((A) / (C)) of the total mass parts of at least one alkyl (meth)acrylate monomer having C1 to C18 to the total mass parts of at least one selected from the group consisting of (C) alkoxy group-containing vinyl monomers and nitrogen-containing vinyl monomers is 1.50 to 8.99, the (B) hydroxyl group-containing copolymerizable vinyl monomer is 0.1 to 2.0 parts by mass, and the (D) crosslinking agent is from the group consisting of trimethylolpropane adduct derivatives of tolylene diisocyanate and isocyanurate compounds of tolylene diisocyanate. The adhesive layer according to [1], wherein the adhesive composition contains at least one selected from the above, and the adhesive composition further contains 0.01 to 1.5 parts by mass of the (D) crosslinking agent per 100 parts by mass of the total acrylic polymer, and the adhesive composition further contains 0.01 to 5.0 parts by mass of an oligomer-type silane coupling agent having at least one organic functional group selected from the group consisting of epoxy groups, mercapto groups, and (meth)acryloyl groups as an (E) silane coupling agent per 100 parts by mass of the total acrylic polymer.

[0008] [3] The adhesive layer according to [1] or [2], characterized in that the gel fraction of the adhesive layer is 50 to 75% by mass, as measured by the gel fraction measurement method described below. • Method for measuring gel fraction: After the aging process is completed by bonding the adhesive layer, which has a thickness of 10 μm, to a polarizing plate, the mass of the sample to be measured is accurately measured from the adhesive layer, which has a thickness of 10 μm, on the surface of the polarizing plate. The sample is then immersed in toluene for 24 hours and filtered through a 200-mesh wire mesh. After drying the filtrate at 100°C for 1 hour, the mass of the residue is accurately measured, and the gel fraction of the adhesive layer is calculated from the following formula (1). Gel fraction (%) = Mass of residue (g) / Mass of sample (g) × 100 ... Equation (1)

[0009] [4] The adhesive layer according to [2], characterized in that the (B) hydroxyl group-containing copolymerizable vinyl monomer is at least one selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide.

[0010] [5] The adhesive composition contains (F) an ionic compound with a melting point of 25°C or higher as an antistatic agent in a proportion of 0.01 to 5.0 parts by mass per 100 parts by mass of the total acrylic polymer, and the surface resistivity of the adhesive layer formed by crosslinking the adhesive composition is 9.0 × 10 11 The adhesive layer according to [2] or [4], characterized in that it is Ω / □ or less.

[0011] [6] The adhesive layer according to any one of [1] to [5], characterized in that the adhesive layer having a thickness of 10 μm is bonded to a polarizing plate having a thickness of 105 μm and a surface substrate of PMMA or COP, and after aging is completed, it is bonded to a panel having an alkali-free glass surface and a screen size of 254 mm (10 inches), and even after a durability test of 105°C × 500 h, there is no peeling or foaming between the polarizing plate and the adhesive layer having a thickness of 10 μm, and the adhesive layer having a thickness of 10 μm is bonded to a polarizing plate having a thickness of 105 μm and a surface substrate of PMMA or COP, and after aging is completed, it is bonded to a panel having an alkali-free glass surface and a screen size of 254 mm (10 inches), and even after a durability test of 85°C × 85% RH × 500 h, there is no peeling or foaming between the polarizing plate and the adhesive layer having a thickness of 10 μm.

[0012] [7] The adhesive layer according to any one of [1] to [6], characterized in that the adhesive layer having a thickness of 10 μm is bonded to a polarizing plate having a thickness of 105 μm and a surface substrate of PMMA or COP, and after aging is completed, it is bonded to a panel having an alkali-free glass surface and a screen size of 254 mm (10 inches), and even after undergoing a durability test at 85°C × 85% RH × 500 h, the haze value of the adhesive layer having a thickness of 10 μm is 1.5% or less.

[0013] [8] An adhesive film characterized in that an adhesive layer according to any one of [1] to [7] is laminated on one side of a resin film. An adhesive film characterized by being an adhesive film for polarizing plates using the adhesive film described in [9] [8].

[10] An adhesive film characterized by having a release film / adhesive layer / release film configuration, wherein an adhesive layer described in any one of [1] to [7] is formed on one side of the release film with a thickness of 1 to 15 μm.

[11] A liquid crystal panel characterized in that an adhesive layer polarizing plate is used, wherein an adhesive layer according to any one of [1] to [7] is laminated on one side of the polarizing plate. An organic EL panel characterized in that a polarizing plate with an adhesive layer, in which the adhesive layer according to any one of [1] to [7] is laminated on one side of the polarizing plate, is used.

Effects of the Invention

[0014] According to the present invention, it is possible to provide an adhesive layer, an adhesive film, a liquid crystal panel, and an organic EL panel that can maintain high performance even when the thickness of the adhesive layer is 15 μm or less.

Brief Description of the Drawings

[0015] [Figure 1] It is a cross-sectional view showing an example of the use of the adhesive layer of the present invention.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the present invention will be described based on preferred embodiments.

[0017] FIG. 1 shows an example of the use of the adhesive layer. The adhesive layer 10 is an adhesive layer for bonding the layer between the polarizing plate 11 and the panel 12, and the thickness of the adhesive layer 10 is 1 to 15 μm.

[0018] When the adhesive layer 10 of the present embodiment is an adhesive layer having a thickness of 10 μm, it maintains the same high performance as that held by an adhesive layer having a thickness of 20 to 25 μm in the prior art. Specifically, the following performances can be mentioned. (1) to (3) represent the durability performance at high temperature or high temperature and high humidity. (4) to (5) represent the degree to which the adhesive force increases after bonding.

[0019] (1) Even after a durability test of bonding the polarizing plate to the panel through an adhesive layer having a thickness of 10 μm and passing through a durability test of 80 ° C. × 500 h, there is no peeling or foaming between the polarizing plate and the adhesive layer having a thickness of 10 μm. (2) After bonding the polarizing plate to the panel via an adhesive layer with a thickness of 10 μm and undergoing a durability test at 85°C × 85% RH × 500 h, there was no peeling or foaming between the polarizing plate and the adhesive layer with a thickness of 10 μm. (3) After bonding the polarizing plate to the panel via an adhesive layer with a thickness of 10 μm and undergoing a durability test at 105°C for 500 hours, there was no peeling or foaming between the polarizing plate and the adhesive layer with a thickness of 10 μm. (4) After bonding a 10 μm thick adhesive layer to a polarizing plate and completing the aging process, the 10 μm thick adhesive layer is bonded to alkali-free glass, and the adhesive strength after 20 minutes is 5.0 N / 25 mm or less. (5) After bonding a 10 μm thick adhesive layer to a polarizing plate and completing the aging process, the 10 μm thick adhesive layer is bonded to alkali-free glass, and the adhesive strength after 10 days at 23°C is 10 N / 25 mm or less.

[0020] In this embodiment, the adhesive layer is preferably an adhesive layer formed by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent. The adhesive composition of this embodiment comprises an acrylic polymer and a crosslinking agent. By crosslinking the adhesive composition of this embodiment, the adhesive layer of this embodiment can be manufactured.

[0021] In the adhesive composition of this embodiment, it is preferable that the acrylic polymer is a copolymer obtained by copolymerizing (A) at least one alkyl (meth)acrylate monomer having C1 to C18 carbon atoms in the alkyl group, (B) at least one hydroxyl group-containing copolymerizable vinyl monomer, and (C) at least one selected from the group consisting of alkoxy group-containing vinyl monomer and nitrogen-containing vinyl monomer.

[0022] In this specification, a (meth)acrylate monomer is a monomer having (meth)acrylate as a polymerizable functional group. The (meth)acrylate may be either acrylate and / or methacrylate, or both.

[0023] (A) The alkyl group of the alkyl(meth)acrylate monomer [component (A)] having C1 to C18 carbon atoms in the alkyl group can be one or more selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, cyclopentyl, cyclohexyl, etc.

[0024] The alkyl group of component (A) may be acyclic (linear or branched) or cyclic. Specific examples of linear alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-octyl, n-nonyl, n-decyl, lauryl, myristyl, palmityl, and stearyl. Specific examples of branched alkyl groups include isopropyl, isobutyl, sec-butyl, tert-butyl, isooctyl, 2-ethylhexyl, 2-octyl, isononyl, isodecyl, isomiristyl, isopalmityl, and isostearyl.

[0025] It is preferable that component (A) of the total 100 parts by mass of the acrylic polymer contains at least 50 parts by mass of butyl acrylate, and more preferably at least 50 parts by mass of n-butyl acrylate.

[0026] (B) Hydroxyl group-containing copolymerizable vinyl monomers [component (B)] include monomers that have a hydroxyl group and also contain one unsaturated double bond in the molecule as a polymerizable functional group, such as a vinyl group, an allyl group, or a (meth)acrylate group. A (meth)acrylate group is preferred as the unsaturated double bond in component (B). However, component (B) is a monomer that does not contain a carboxyl group.

[0027] Specific examples of component (B) include at least one selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide.

[0028] As at least one selected from the group consisting of an alkoxy group-containing vinyl monomer and a nitrogen-containing vinyl monomer [(component (C))], there are monomers that contain an alkoxy group or a nitrogen atom and contain one unsaturated double bond such as a vinyl group, an allyl group, or a (meth)acrylate group as a polymerizable functional group in the molecule. However, component (C) is a monomer that contains neither a hydroxyl group nor a carboxyl group.

[0029] Examples of the alkoxy group-containing vinyl monomer include compounds represented by the general formula CH2=CH(R 1 )-CO-O-(R 2 O)nR 3 (where R 1 is a hydrogen atom or methyl, R 2 is alkylene, R 3 is alkyl, and n is an integer of 1 or more).

[0030] Examples of the alkylene of R 2 in the above general formula include one or more selected from ethylene, propylene, butylene, etc. Examples of the alkyl of R 3 include methyl, ethyl, etc. Specific examples of the alkoxy group-containing vinyl monomer include methoxyalkyl (meth)acrylate, ethoxyalkyl (meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, ethoxypolyalkylene glycol (meth)acrylate, etc.

[0031] Nitrogen-containing vinyl monomers are not particularly limited, but examples include N,N-dialkyl-substituted acrylic monomers, N-vinyl-substituted lactams, and N-(meth)acryloyl-substituted cyclic amines. Examples of N,N-dialkyl-substituted acrylic monomers (containing an amino group or amide group) include N,N-dialkyl(meth)acrylamide, (dialkylamino)alkyl(meth)acrylate, and (dialkylamino)alkyl(meth)acrylamide. The alkyl group in N,N-dialkyl-substituted acrylic monomers can be one or more selected from methyl, ethyl, propyl, butyl, etc. Examples of N-vinyl-substituted lactams include N-vinylpyrrolidone and N-vinylcaprolactam. Examples of N-(meth)acryloyl-substituted cyclic amines include N-(meth)acryloylpyrrolidine, N-(meth)acryloylpiperidine, and N-(meth)acryloylmorpholine.

[0032] To maintain high performance even when the adhesive layer thickness is 15 μm or less, it is preferable that, of the total 100 parts by mass of the acrylic polymer, component (C) is 10 parts by mass or more, the ratio of parts by mass of component (A) to parts by mass of component (C) ((A) / (C)) is 1.50 to 8.99, and component (B) is 0.1 to 2.0 parts by mass. Furthermore, it is preferable that the acrylic polymer does not contain carboxyl group-containing copolymerizable vinyl monomers and that the acid value of the acrylic polymer is 0.1 or less. Acrylic polymers with a low acid value can be obtained by not copolymerizing monomers having acidic functional groups such as carboxyl groups.

[0033] To maintain high performance even when the adhesive layer thickness is 15 μm or less, the weight-average molecular weight (MW) of the acrylic polymer is preferably 1.5 million to 3.5 million. The polymerization method of the copolymer used as the acrylic polymer is not particularly limited, and any known polymerization method such as solution polymerization or emulsion polymerization can be used as appropriate.

[0034] The adhesive composition of this embodiment contains a crosslinking agent (D) [component (D)]. Component (D) is preferably a polyisocyanate compound with two or more functions, and more preferably a polyisocyanate compound with three or more functions. To maintain high performance even when the adhesive layer thickness is 15 μm or less, component (D) is preferably at least one selected from the group consisting of trimethylolpropane adducts of tolylene diisocyanate and isocyanurate compounds of tolylene diisocyanate. The proportion of component (D) is preferably 0.01 to 1.5 parts by mass per 100 parts by mass of the total acrylic polymer.

[0035] The gel fraction of the adhesive layer formed by crosslinking the adhesive composition containing component (D) is preferably 50 to 75% by mass, as measured by the gel fraction measurement method described below. • Method for measuring gel fraction: After bonding a 10 μm thick adhesive layer to a polarizing plate and completing the aging process, the mass of the sample is accurately measured from the 10 μm thick adhesive layer on the surface of the polarizing plate. The sample is then immersed in toluene for 24 hours and filtered through a 200-mesh wire mesh. The filtered material is then dried at 100°C for 1 hour, and the mass of the residue is accurately measured. The gel fraction of the adhesive layer is then calculated from the following formula (1). Gel fraction (%) = Mass of residue (g) / Mass of sample (g) × 100 ... Equation (1)

[0036] The adhesive composition of this embodiment contains (E) a silane coupling agent [component (E)]. Component (E) is an oligomer-type silane coupling agent having at least one organic functional group selected from the group consisting of epoxy groups, mercapto groups, and (meth)acryloyl groups. The proportion of component (E) is preferably 0.01 to 5.0 parts by mass per 100 parts by mass of the total acrylic polymer. Compared to monomer-type silane coupling agents having one alkoxysilyl group, oligomer-type silane coupling agents have a larger number of reactive organic functional groups.

[0037] The adhesive composition of this embodiment preferably contains (F) an antistatic agent [component (F)]. Examples of component (F) include ionic compounds with a melting point of 25°C or higher. The proportion of component (F) is preferably 0.01 to 5.0 parts by mass per 100 parts by mass of the total acrylic polymer. The surface resistivity of the adhesive layer formed by crosslinking the adhesive composition containing component (E) is 9.0 × 10⁻⁶. 11 It is preferable that the value is Ω / □ or less.

[0038] The cation of the ionic compound may be one selected from the group consisting of pyridinium, imidazolium, sulfonium, phosphonium, pyrrolidinium, guanidinium, ammonium, isouronium, thiouronium, piperidinium, pyrazolium, methylium, lithium, and ammonium. Of these, cations other than lithium (Li) may have one or more substituents. Examples of substituents include hydrocarbon groups such as alkyl, phenyl, and benzyl.

[0039] Anions of ionic compounds include sulfonate anions (XSO3 - ), imid anion (X2N - ), Methido anion (X3C - ), borate anion (X4B - Examples include the following. In these anions, X can be a group containing a fluorine atom. Examples of sulfonate anions include fluorogroup-containing alkane sulfonate anions. Examples of imide anions include bis(fluorogroup-containing sulfonyl)imide anions. Examples of borate anions include tetrakis(fluorogroup-containing phenyl)borate anions.

[0040] In addition to the examples given above, the adhesive composition of this embodiment may appropriately incorporate known additives such as antioxidants, surfactants, plasticizers, fillers, crosslinking catalysts, crosslinking accelerators, and crosslinking retarders as optional components. These may be used individually or in combination of two or more.

[0041] The adhesive layer in this embodiment is an adhesive layer with a thickness of 1 to 15 μm, but when the adhesive layer has a thickness of 10 μm, it is preferable that in addition to the above-mentioned (1) to (5), it also has at least one of the following properties (6) to (8).

[0042] (6) After the aging process is completed by bonding a 10 μm thick adhesive layer to a predetermined polarizing plate, and then bonding it to a predetermined panel, there is no peeling or foaming between the polarizing plate and the 10 μm thick adhesive layer even after a durability test at 105°C for 500 hours. (7) After bonding a 10 μm thick adhesive layer to a predetermined polarizing plate and completing the aging process, it is then bonded to a predetermined panel and subjected to a durability test at 85°C × 85% RH × 500 h. Even after this test, there is no peeling or foaming between the polarizing plate and the 10 μm thick adhesive layer. (8) After bonding a 10 μm thick adhesive layer to a predetermined polarizing plate and completing the aging process, it is then bonded to a predetermined panel and subjected to a durability test at 85°C × 85% RH × 500 h, and even after this test, the haze value of the 10 μm thick adhesive layer remains 1.5% or less.

[0043] In (6) to (8) above, a specified polarizing plate is a polarizing plate having a thickness of 105 μm and a surface substrate of polymethyl methacrylate (PMMA) or cycloolefin polymer (COP). A specified panel is a panel having an alkali-free glass surface and a screen size of 254 mm (10 inches).

[0044] The adhesive film of this embodiment may have a configuration in which the adhesive layer of this embodiment is laminated on one side of a resin film. The adhesive film of this embodiment may have a configuration of release film / adhesive layer / release film, in which the adhesive layer of this embodiment is formed on one side of a release film to a thickness of 1 to 15 μm. The adhesive film of this embodiment may be used as an adhesive film for polarizing plates.

[0045] The adhesive film of this embodiment can be used for interlayer bonding of optical components such as polarizing plates and panels. The applications of the adhesive film are not particularly limited, but include electronic devices such as liquid crystal panels, organic EL panels, and touch panels, as well as various optical films. Examples of optical films include polarizing films, phase difference films, lens films, anti-reflective films, hard coat films, transparent conductive films, anti-glare films, ultraviolet absorbing films, infrared absorbing films, optical compensation films, and brightness enhancement films.

[0046] The adhesive optical film of this embodiment has a structure in which the above-described adhesive layer is laminated on at least one surface of the optical film. When applied as an optical film to a polarizing plate, an adhesive-layered polarizing plate, in which the adhesive layer is laminated on one side of the polarizing plate, can be used in electronic devices such as liquid crystal panels, organic EL panels, and touch panels.

[0047] The surface treatment applied to the surface of a polarizing plate such as a polarizing film may be at least one selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment. Here, AG stands for Anti-Glare, LR stands for Low-Reflection, and AR stands for Anti-Reflection. [Examples]

[0048] The present invention will be specifically described below with reference to examples.

[0049] <Manufacturing of acrylic polymers> Nitrogen gas was introduced into a reactor equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube to replace the air in the reactor with nitrogen gas. Then, monomers (A), (B), and (C) shown in Table 1 and a solvent (ethyl acetate) were added, and polymerization was carried out dropwise while adding azobisisobutyronitrile as a polymerization initiator to obtain an acrylic polymer solution.

[0050] The meanings of the abbreviations for materials used in Table 1 are as follows. In columns (A) to (F) of Table 1, the numerical values ​​following the abbreviations for materials represent the values ​​in parts by mass.

[0051] Group (A) • BA: Butyl acrylate (preferably n-butyl acrylate) • EA: Ethyl acrylate • MA: Methyl acrylate MMA: Methyl methacrylate TBA: t-butyl acrylate PHEA: Phenoxyethyl acrylate

[0052] Group (B) • 8HOA: 8-Hydroxyoctylacrylate • 6HHA: 6-Hydroxyhexylacrylate • 4HBA: 4-hydroxybutyl acrylate • HEA: 2-hydroxyethyl acrylate AAc: Acrylic acid

[0053] Group (C) C-1: Methoxypolyethylene glycol methacrylate • C-2: Methoxyethyl acrylate C-3: Dimethylaminoethyl acrylate C-4: Dimethylacrylamide ·C-5:N-vinyl-2-pyrrolidone

[0054] (D) Group (Takenate® is a product name of Mitsui Chemicals, Inc.) • D-1: Takenate® D101E, trimethylolpropane (TMP) adduct of tolylene diisocyanate (TDI) (75% ethyl acetate solution) • D-2: Takenate (registered trademark) D262, tolylene diisocyanate (TDI) isocyanurate compound (75% butyl acetate solution) • D-3: Takenate® D-160N, trimethylolpropane (TMP) adduct of hexamethylene diisocyanate (HDI) (75% ethyl acetate solution) D-4: Benzoyl peroxide

[0055] (E) Group (all are product names of Shin-Etsu Chemical Co., Ltd.) • E-1: KR-519, mercapto group-containing oligomer • E-2: KR-516, epoxy group-containing oligomer • E-3:X-12-1154, mercapto group-containing oligomer • E-4: KR-513, acryloyl group-containing oligomer • E-5: KBM-403, epoxy group-containing silane coupling agent (monomer type)

[0056] (F) group F-1: Tributylmethylammonium N,N-bis(trifluoromethanesulfonyl)imide (melting point 27°C) F-2: 1-methyl-3-octylpyridinium nonafluorobutanesulfonate (melting point 41°C) F-3: Methoxymethyltriphenylphosphonium tetrakis(pentafluorophenyl)borate (melting point 149°C) F-4: 1-Butylpyridinium bis(trifluoromethanesulfonyl)imide (liquid)

[0057] [Table 1]

[0058] <Method for measuring adhesive strength> A 10 μm thick adhesive layer is transferred to one side of a polarizing plate to create a sample. The sample is then bonded to alkali-free glass using a 2 kg roller in one pass, and the adhesive strength is measured. For the adhesive strength measurement, two samples are prepared: one for measurement 20 minutes after bonding to alkali-free glass, and another for measurement 10 days at 23°C after bonding to alkali-free glass.

[0059] <Method for measuring gel fraction> According to the durability measurement method described below, a sample is taken from the aged adhesive layer, its mass is accurately measured, and it is immersed in toluene for 24 hours before being filtered through a 200-mesh wire mesh. After drying the filtrate at 100°C for 1 hour, the mass of the residue is accurately measured, and the gel fraction of the adhesive layer is calculated from the following formula (1). Gel fraction (%) = Mass of residue (g) / Mass of sample (g) × 100 ... Equation (1)

[0060] <Method for measuring surface resistivity> After the aging of the adhesive layer is completed according to the durability measurement method described below, the surface resistivity of the adhesive layer is measured using a resistivity meter. In Table 2, the surface resistivity value is given as "m × 10 +n This was expressed using the formula "mE+n" (where m is a decimal and n is an integer).

[0061] <Method for measuring durability> A 10 μm thick adhesive layer is transferred to one side of a polarizing plate, and after aging at 23°C for 4 days, it is bonded to an alkali-free glass (EAGLE XG®) with a thickness of 0.7 mm as the substrate. After autoclaving at 50°C at 5 atm for 20 minutes, the sample is placed in a predetermined durable atmosphere (3 types: 80°C, 85°C at 85% RH, and 105°C), and after a predetermined time (500 h), it is removed and the condition between the polarizing plate and the adhesive layer (presence or absence of peeling, foaming, etc.) is checked with a magnifying glass. ○: No peeling or foaming. △: Minor peeling and foaming present. ×: Peeling and foaming present

[0062] <Method for measuring haze> After completing the aging of the adhesive layer according to the durability measurement method described above, the haze value (%) of the adhesive layer is measured in accordance with JIS K7136 using a haze meter (product name: NDH4000) manufactured by Nippon Denshoku Industries Co., Ltd.

[0063] [Table 2]

[0064] When using polarizers for the evaluation in Table 2, polarizers equipped with the surface substrates (PMMA or COP) shown in Table 2 were used. According to Examples 1-5, high performance could be maintained even when the thickness of the adhesive layer was 15 μm or less. According to Comparative Examples 1-4, high performance could not be maintained when the thickness of the adhesive layer was 15 μm or less. [Explanation of Symbols]

[0065] 10...Adhesive layer, 11...Polarizing plate, 12...Panel.

Claims

1. An adhesive layer for bonding layers between a polarizing plate and a panel, The thickness of the adhesive layer is 1 to 15 μm. Even after bonding a polarizing plate to a panel via the adhesive layer with a thickness of 10 μm and undergoing a durability test at 80°C for 500 hours, there was no peeling or foaming between the polarizing plate and the adhesive layer with a thickness of 10 μm. Even after bonding a polarizing plate to a panel via the adhesive layer with a thickness of 10 μm and undergoing a durability test at 85°C × 85% RH × 500 h, there was no peeling or foaming between the polarizing plate and the adhesive layer with a thickness of 10 μm. Even after bonding a polarizing plate to a panel via the adhesive layer with a thickness of 10 μm and undergoing a durability test at 105°C for 500 hours, there was no peeling or foaming between the polarizing plate and the adhesive layer with a thickness of 10 μm. After bonding the adhesive layer with a thickness of 10 μm to a polarizing plate and completing the aging process, the adhesive layer with a thickness of 10 μm is bonded to alkali-free glass, and the adhesive strength after 20 minutes is 5.0 N / 25 mm or less. An adhesive layer characterized in that, after bonding the adhesive layer, which has a thickness of 10 μm, to a polarizing plate and completing the aging process, the adhesive layer, which has a thickness of 10 μm, is bonded to alkali-free glass, and the adhesive strength after 10 days at 23°C is 10 N / 25 mm or less.

2. The adhesive layer is an adhesive layer formed by crosslinking an adhesive composition containing an acrylic polymer and (D) a crosslinking agent. The aforementioned acrylic polymer (A) At least one alkyl (meth)acrylate monomer having C1 to C18 carbon atoms in the alkyl group, (B) At least one hydroxyl group-containing copolymerizable vinyl monomer, (C) A copolymer obtained by copolymerizing at least one selected from the group consisting of alkoxy group-containing vinyl monomers and nitrogen-containing vinyl monomers. The weight-average molecular weight of the aforementioned acrylic polymer is between 1.5 million and 3.5 million. The acrylic polymer does not contain a carboxyl group-containing copolymerizable vinyl monomer. The acid value of the aforementioned acrylic polymer is 0.1 or less. Of the total 100 parts by mass of the acrylic polymer, (A) the alkyl (meth)acrylate monomer having C1 to C18 in the alkyl group contains at least 50 parts by mass of butyl acrylate, (C) at least one selected from the group consisting of alkoxy group-containing vinyl monomers and nitrogen-containing vinyl monomers is 10 parts by mass or more, the ratio ((A) / (C)) of the total parts by mass of at least one of the alkyl (meth)acrylate monomers having C1 to C18 in the alkyl group to the total parts by mass of at least one selected from the group consisting of alkoxy group-containing vinyl monomers and nitrogen-containing vinyl monomers is 1.50 to 8.99, and (B) the hydroxyl group-containing copolymerizable vinyl monomer is 0.1 to 2.0 parts by mass. The (D) crosslinking agent is at least one selected from the group consisting of trimethylolpropane adduct compounds of tolylene diisocyanate and isocyanurate compounds of tolylene diisocyanate. The adhesive composition contains the (D) crosslinking agent in an amount of 0.01 to 1.5 parts by mass per 100 parts by mass of the total acrylic polymer. The adhesive layer according to claim 1, further characterized in that the adhesive composition contains (E) an oligomer-type silane coupling agent having at least one organic functional group selected from the group consisting of epoxy groups, mercapto groups, and (meth)acryloyl groups, in an amount of 0.01 to 5.0 parts by mass per 100 parts by mass of the total acrylic polymer.

3. The adhesive layer according to claim 1, characterized in that the gel fraction of the adhesive layer is 50 to 75% by mass, as measured by the gel fraction measurement method described below. - Method for measuring gel fraction: After the aging process is completed by bonding the adhesive layer, which has a thickness of 10 μm, to a polarizing plate, the mass of the sample to be measured is accurately measured from the adhesive layer, which has a thickness of 10 μm, on the surface of the polarizing plate. The sample is then immersed in toluene for 24 hours and filtered through a 200-mesh wire mesh. After drying the filtered material at 100°C for 1 hour, the mass of the residue is accurately measured, and the gel fraction of the adhesive layer is calculated from the following formula (1). Gel fraction (%) = Mass of residue (g) / Mass of sample (g) × 100 ... Equation (1)

4. The adhesive layer according to claim 2, characterized in that the (B) hydroxyl group-containing copolymerizable vinyl monomer is at least one selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide.

5. The adhesive composition contains (F) an ionic compound with a melting point of 25°C or higher as an antistatic agent in a proportion of 0.01 to 5.0 parts by mass per 100 parts by mass of the total acrylic polymer. The surface resistivity of the crosslinked adhesive layer of the aforementioned adhesive composition is 9.0 × 10 １１ The adhesive layer according to claim 2, characterized in that it is less than or equal to Ω / □.

6. After bonding the 10 μm thick adhesive layer to a polarizing plate with a thickness of 105 μm and a surface substrate of PMMA or COP, and completing the aging process, it was bonded to a panel with an alkali-free glass surface and a screen size of 254 mm (10 inches), and even after a durability test at 105°C for 500 hours, there was no peeling or foaming between the polarizing plate and the 10 μm thick adhesive layer. The adhesive layer according to claim 1, characterized in that even after bonding the adhesive layer, which is 10 μm thick, to a polarizing plate with a thickness of 105 μm and a surface substrate of PMMA or COP, and completing the aging process, bonding it to a panel with an alkali-free glass surface and a screen size of 254 mm (10 inches), and undergoing a durability test at 85°C × 85% RH × 500 h, there is no peeling or foaming between the polarizing plate and the adhesive layer, which is 10 μm thick.

7. The adhesive layer according to claim 6, characterized in that even after bonding the adhesive layer, which is 10 μm thick, to a polarizing plate with a thickness of 105 μm and a surface substrate of PMMA or COP, and completing the aging process, bonding it to a panel with an alkali-free glass surface and a screen size of 254 mm (10 inches), and undergoing a durability test at 85°C × 85% RH × 500 h, the haze value of the adhesive layer, which is 10 μm thick, is 1.5% or less.

8. An adhesive film characterized in that an adhesive layer according to any one of claims 1 to 7 is laminated on one side of a resin film.

9. An adhesive film characterized by being an adhesive film for polarizing plates using the adhesive film described in claim 8.

10. An adhesive film characterized by having a release film / adhesive layer / release film configuration, wherein an adhesive layer according to any one of claims 1 to 7 is formed on one side of the release film with a thickness of 1 to 15 μm.

11. A liquid crystal panel characterized in that an adhesive layer-coated polarizing plate is used, wherein an adhesive layer according to any one of claims 1 to 7 is laminated on one side of the polarizing plate.

12. An organic EL panel characterized in that an adhesive-coated polarizing plate is used, wherein an adhesive layer according to any one of claims 1 to 7 is laminated on one side of the polarizing plate.

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