In-cell liquid crystal panel

Abstract

The present invention provides an adhesive composition having high durability. The present invention relates to an In-cell type liquid crystal panel (1) which is an In-cell type liquid crystal panel (1) comprising a first polarizing film (30a), a first transparent substrate (10a), and an adhesive layer (20a) disposed between them, the adhesive layer (20a) being formed from an adhesive composition containing a (meth)acrylic polymer, a crosslinking agent, and an antistatic agent, the (meth)acrylic polymer being a polymer of a monomer composition containing more than 50 mass% of an alkoxyalkyl (meth)acrylate and 0.1 to 15 mass% of a functional group-containing monomer.

Description

Technical Field

[0001] The present invention relates to an In-cell type liquid crystal panel, and more particularly to an In-cell type liquid crystal panel having high durability. Background Art

[0002] Liquid crystal panels usually have a structure in which a liquid crystal cell array is sandwiched between two transparent substrates and a polarizing film is installed on the outside. Here, one transparent substrate is usually a glass substrate with a color filter and electrodes, and the other is a glass substrate with a thin film transistor circuit.

[0003] Touch panel type liquid crystal panels can be divided into external liquid crystal panels and internal liquid crystal panels. As internal liquid crystal panels, on-cell liquid crystal panels and in-cell liquid crystal panels are known. External liquid crystal panels are a method of placing a touch panel outside the liquid crystal, which requires a physical space between the liquid crystal and the touch panel, so the thickness becomes larger.

[0004] For built-in On-cell type LCD panels and In-cell type LCD panels, the components with touch panel functions are different. On-cell type LCD panels are a method in which a touch sensor is inserted between the glass substrate and the polarizing film on the viewing side (front side), while In-cell type LCD panels are a method in which the touch sensor is combined with two glass substrates and the liquid crystal unit array.

[0005] Figure 1 The layer structure of the In-cell type liquid crystal panel is shown as an example. The In-cell type liquid crystal panel 1 has a first polarizing film 30a, a first adhesive layer 20a, a first transparent substrate 10a, a liquid crystal layer 4, a touch sensing functional unit 5, a second transparent substrate 10b, a second adhesive layer 20b, and a second polarizing film 30b. The first adhesive layer 20a and the second adhesive layer 20b not only need to have the bonding property between the polarizing film and the transparent substrate, but also must have a low surface resistance, so they contain an antistatic agent. Compared with the On-cell type liquid crystal unit having a sensor electrode on the transparent substrate of the liquid crystal unit, the In-cell type liquid crystal panel is easy to be charged, so a lower surface resistance is required.

[0006] Patent Document 1 discloses such an In-cell type liquid crystal panel including an adhesive layer.

[0007] Prior art literature Patent Literature Patent Document 1: International Publication No. 2018 / 181490 Summary of the invention Problem that the invention aims to solve The present invention provides an In-cell type liquid crystal panel with high durability.

[0008] Means used to solve problems The present inventors have found that the above-mentioned problems can be solved by the present invention having the following aspects.

[0009] <Option 1> An In-cell type liquid crystal panel comprises a first polarizing film, a first transparent substrate, and an adhesive layer disposed between the first polarizing film and the first transparent substrate. The adhesive layer is formed of an adhesive composition containing a (meth)acrylic polymer, a crosslinking agent, and an antistatic agent. The (meth)acrylic polymer is a polymer of a monomer composition containing more than 50% by mass of an alkoxyalkyl (meth)acrylate and 0.1 to 15% by mass of a functional group-containing monomer.

[0010] <Option 2> The In-cell liquid crystal panel according to claim 1, wherein the monomer composition contains 80% by mass or more of an alkoxyalkyl (meth)acrylate.

[0011] <Option 3> The In-cell liquid crystal panel according to claim 1, wherein the (meth)acrylic polymer has a weight average molecular weight of 1.2 million or more.

[0012] <Option 4> An In-cell type liquid crystal panel according to Scheme 1, wherein the variation ratio (b / a) of the surface resistivity of the adhesive layer before and after the durability test is 5.0 or less, wherein a is the surface resistivity of the adhesive layer just after peeling off the release film of a polarizing film with an adhesive layer in a state where a release film is provided on the adhesive layer, and b is the surface resistivity of the adhesive layer just after peeling off the release film after placing the polarizing film with the adhesive layer affixed with the release film in a humidified environment of 85°C×85%RH for 24 hours and further drying at 40°C for 1 hour.

[0013] <Option 5> The In-cell type liquid crystal panel according to Scheme 1, wherein the polarization degree after the durability test is 99.0% or more, and the polarization degree after the durability test refers to the polarization degree measured after a polarizing film with an adhesive layer is adhered to the In-cell type liquid crystal unit, kept in an autoclave adjusted to 50°C / 5 atmospheric pressure for 20 minutes, and then placed in a humidified environment of 85°C and 85%RH for 24 hours.

[0014] <Option 6> The In-cell liquid crystal panel according to any one of claims 1 to 5, comprising An in-cell type liquid crystal unit comprises a liquid crystal layer, a first transparent substrate and a second transparent substrate sandwiching the liquid crystal layer on both sides, and a touch sensing functional part between the first transparent substrate and the second transparent substrate. The device further comprises a first polarizing film disposed on the viewing side of the in-cell type liquid crystal unit, a second polarizing film disposed on the opposite side to the viewing side, and the adhesive layer disposed between the first polarizing film and the first transparent substrate of the in-cell type liquid crystal unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The layer structure of an In-cell type liquid crystal panel is exemplified.

[0016] Figure 2 It is a cross-sectional view schematically showing an example of a laminated body.

[0017] Figure 3 It is a cross-sectional view schematically showing another example of the laminated body. DETAILED DESCRIPTION

[0018] <In-cell type LCD panel> In one embodiment, the present invention relates to an In-cell type liquid crystal panel. The In-cell type liquid crystal panel includes a first polarizing film, a first transparent substrate, and an adhesive layer disposed between the first polarizing film and the first transparent substrate, wherein the adhesive layer is formed by an adhesive composition containing a (meth)acrylic polymer, a crosslinking agent, and an antistatic agent. Here, the (meth)acrylic polymer is a polymer of a monomer composition containing more than 50% by mass of an alkoxyalkyl (meth)acrylate and 0.1 to 15% by mass of a functional group-containing monomer.

[0019] The present inventors have found that, with the adhesive layer formed from such an adhesive composition, the surface resistivity can be sufficiently reduced even when the amount of the antistatic agent is reduced compared to the prior art. In addition, even when the amount of the antistatic agent is increased, since the (meth) acrylic polymer has good compatibility with the antistatic agent, the In-cell type liquid crystal panel of the present invention can suppress the leakage of the antistatic agent even when it is placed for a long time under high temperature and high humidity conditions, thereby having high durability.

[0020] In the In-cell type liquid crystal panel, the structure other than the adhesive layer can be the same as that of the known In-cell type liquid crystal panel. For example, the In-cell type liquid crystal panel has: an In-cell type liquid crystal unit, which has a liquid crystal layer, a first transparent substrate and a second transparent substrate sandwiching the liquid crystal layer on both sides, and a touch sensing functional part between the first transparent substrate and the second transparent substrate; and a first polarizing film arranged on the visual recognition side of the In-cell type liquid crystal unit and a second polarizing film arranged on the opposite side of the visual recognition side, and the above-mentioned adhesive layer is arranged between the first polarizing film and the first transparent substrate of the In-cell type liquid crystal unit. Here, the touch sensing functional part can be composed of a touch sensor and a touch sensing electrode part related to the touch drive function. These various structures are also well known, for example, the same structure as Patent Document 1 can be adopted.

[0021] like Figure 1 As shown, the In-cell type liquid crystal panel 1 can have a first polarizing film 30a, a first adhesive layer 20a, a first transparent substrate 10a, a liquid crystal layer 4, a touch sensing functional part 5, a second transparent substrate 10b, a second adhesive layer 20b, and a second polarizing film 30b in sequence. The touch sensing functional part 5 can be configured in various positions depending on the relationship with the liquid crystal layer 4 as disclosed in patent document 1.

[0022] The first and second polarizing films are bonded to the first and second adhesive layers, respectively, and a polarizing film having a transparent protective film on one or both sides of the polarizing element is generally used. The polarizing element is not particularly limited, and a polarizing element containing a polyvinyl alcohol film and a dichroic substance such as iodine is preferably used. As the material constituting the transparent protective film, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture shielding, isotropy, etc. can be used, and cellulose resins such as triacetyl cellulose, cyclic olefin resins, etc. can be cited. The polarizing element and the transparent protective film are bonded by a known bonding agent.

[0023] Between the polarizing film and the adhesive layer, there may be an anchor layer as described in Patent Document 1. The anchor layer may be formed of a composition comprising a conductive polymer and a binder. As the conductive polymer, polyaniline, polythiophene, etc. may be used, and as the binder, polyurethane resins, polyester resins, acrylic resins, etc. may be cited in particular.

[0024] The first and second transparent substrates are bonded to the first and second adhesive layers, respectively, and may be made of glass or a polymer film. As the polymer film, for example, a film comprising polyethylene terephthalate, a cyclic olefin resin, a polycarbonate, etc. may be mentioned. When the transparent substrate is formed of glass, its thickness may be set to, for example, about 0.1 mm to 1 mm. When the transparent substrate is formed of a polymer film, its thickness may be set to, for example, about 10 μm to 200 μm. The transparent substrate may have an easy bonding layer or a hard coating layer on its surface.

[0025] The first and second adhesive layers include the adhesive composition described below. The adhesive layers can be obtained, for example, by coating, drying and / or curing the following adhesive composition.

[0026] The adhesive layer can be formed by coating the adhesive composition on a polarizing film and / or a transparent substrate as an adherend, or on the surface of a release film (spacer), for example, drying at 50°C to 150°C depending on the type of solvent, attaching a release film to the surface of the adhesive layer that does not contact other layers, and then curing at 23°C to 50°C for, for example, 3 to 10 days.

[0027] Examples of the method for coating the adhesive composition include known methods such as spin coating, knife coating, roll coating, rod coating, blade coating, die coating, and gravure coating, and blade coating is particularly preferred.

[0028] The thickness of the adhesive layer may be 5 μm or more, 7 μm or more, 10 μm or more, or 15 μm or less, or 50 μm or less, 30 μm or less, 20 μm or less, or 15 μm or less. For example, the thickness of the adhesive layer may be 5 μm or more and 50 μm or less, or 10 μm or more and 30 μm or less.

[0029] When the surface resistivity of the adhesive layer is measured by the method described in the Examples, it can be 1.0×10 10 Ω / □ or less, 5.0×10 9 Ω / □ or less, 2.0×10 9 Ω / □ or less, 1.0×10 9 Ω / □ or less, 5.0×10 8 Ω / □ or less, or 3.0×10 8 Ω / □ or less, can be 1.0×10 7 Ω / □ or more, 5.0×10 7 Ω / □ or more, 1.0×10 8 Ω / □ or more, or 5.0×10 8 Ω / □ or more.

[0030] The variation ratio (b / a) of the surface resistivity before and after the durability test is preferably less than 10.0, less than 5.0, less than 3.0, less than 2.0, or less than 1.5. That is, the surface resistivity of the adhesive layer is preferably unchanged before and after the durability test. Here, a refers to the surface resistivity of the adhesive layer just after the release film is peeled off, in which a polarizing film with an adhesive layer is prepared in a state where a release film is provided on the adhesive layer. In addition, b refers to the surface resistivity of the adhesive layer side just after the release film is released after the polarizing film with an adhesive layer affixed with a release film is placed in a humidified environment of 85°C×85%RH for 24 hours and further dried at 40°C for 1 hour.

[0031] The polarization degree of the adhesive layer after the durability test is preferably 99.00% or more, 99.50% or more, 99.80% or more, 99.90% or more, or 99.95% or more. Here, the polarization degree after the durability test refers to the polarization degree measured after the polarizing film with the adhesive layer is bonded to the In-cell type liquid crystal unit, kept in an autoclave adjusted to 50°C / 5 atmosphere for 20 minutes, and then placed in a humidified environment of 85°C and 85%RH for 24 hours. The polarization degree is measured by the method described in the examples.

[0032] <Adhesive composition> In one embodiment, the present invention relates to an adhesive composition. The adhesive composition is particularly suitable for bonding a polarizing film and a transparent substrate of a liquid crystal panel.

[0033] <(Meth)acrylic acid polymer> The adhesive composition forming the adhesive layer contains a (meth)acrylic polymer, which is a polymer of a monomer composition containing more than 50% by mass of an alkoxyalkyl (meth)acrylate and 0.1 to 15% by mass of a functional group-containing monomer.

[0034] The (meth)acrylic acid polymer preferably has a weight average molecular weight (Mw) of 600,000 or more. The weight average molecular weight may be 800,000 or more, 1,000,000 or more, 1,200,000 or more, 1,300,000 or more, 1,500,000 or more, 1,650,000 or more, 1,800,000 or more, or 1,900,000 or more, and may be 3,000,000 or less, 2,800,000 or less, 2,500,000 or less, 2,200,000 or less, 1,800,000 or less, or 1,650,000 or less. For example, the weight average molecular weight may be 1,200,000 or more and 3,000,000 or less, or 1,300,000 or more and 2,000,000 or less. If it is within such a range, it will not cause the problem of coating property to the adhesive composition, and can bring extremely high heat resistance to the obtained adhesive layer.

[0035] The polydispersity (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) of the (meth)acrylic polymer to the number average molecular weight (Mn) may be 15.0 or less, 10.0 or less, 8.0 or less, 6.0 or less, or 5.0 or less, and may be 1.5 or more, 2.0 or more, 3.0 or more, or 4.0 or more. For example, the polydispersity of the (meth)acrylic polymer may be 1.5 or more and 15.0 or less, or 2.0 or more and 8.0 or less.

[0036] The weight average molecular weight and the number average molecular weight were determined in terms of standard polystyrene using GPC (gel permeation chromatography) under the following conditions.

[0037] <GPC measurement conditions> Measuring device: HLC-8120GPC (manufactured by Tosoh) GPC column composition: The following five columns (all manufactured by Tosoh) (1) TSK-GEL HXL-H (guard column) (2) TSK-GEL G7000HXL (3) TSK-GEL GMHXL (4) TSK-GEL GMHXL (5) TSK-GEL G2500HXL Sample concentration: 1.0 mg / cm 3 dilute with tetrahydrofuran Mobile phase solvent: tetrahydrofuran Flow rate: 1.0cm 3 / point Column temperature: 40°C <(Meth)acrylic acid polymer-(meth)acrylate alkoxyalkyl ester> The monomer composition for obtaining the (meth)acrylic polymer contains an alkoxyalkyl (meth)acrylate. The alkoxyalkyl (meth)acrylate is a monomer in which at least one hydrogen atom of the alkyl group of the alkyl (meth)acrylate is substituted with an alkoxy group or a compound having an alkoxy group. Examples of the compound in which at least one hydrogen atom of the alkyl group of the alkyl (meth)acrylate is substituted with a compound having an alkoxy group include polyalkylene glycol (meth)acrylate.

[0038] For example, the monomer is represented by CH2=CR1-COO-R2, where R1 is a hydrogen atom or a methyl group, R2 is a linear or branched alkyl or aralkyl group having 14 or less carbon atoms, and at least one of the hydrogen atoms constituting these groups is replaced by a -O-(C n H 2n O) m-R3 is substituted, n represents an integer of 1 to 4, m represents 0 or an integer of 1 to 10, and R3 constitutes a linear or branched alkyl group having 14 or less carbon atoms.

[0039] Specifically, examples of the alkoxyalkyl (meth)acrylate include methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, ethyl carbitol acrylate, 2-ethylhexyl-diethylene glycol acrylate, methoxy-polyethylene glycol acrylate, ethoxy-diethylene glycol acrylate, and the like. Among these, 2-methoxyethyl (meth)acrylate can be particularly mentioned.

[0040] The (meth) alkoxyalkyl ester contains more than 50% by mass in the monomer composition. For example, in the monomer composition, the (meth) alkoxyalkyl ester may contain 51% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, or 98% by mass or more, and may contain 99.9% by mass or less, 99.5% by mass or less, 99.0% by mass or less, 98% by mass or less, 95% by mass or less, 90% by mass or less, or 80% by mass or less. For example, in the monomer composition, the (meth) alkoxyalkyl ester may contain 70% by mass or more and 99.9% by mass or less, or 85% by mass or more and 99.9% by mass or less.

[0041] Compared with other monomers used in the art, when the content of (meth)acrylic acid alkoxyalkyl ester in the (meth)acrylic polymer is in a high range as described above, the resistance of the adhesive layer can be reduced. Generally, the adhesive layer reduces the resistance by using an antistatic agent such as an ionic compound, but the resistance can be further reduced by changing the composition of the (meth)acrylic polymer. In addition, the above-mentioned (meth)acrylic polymer has high compatibility with the antistatic agent commonly used in the art, suppresses the seepage of the antistatic agent, and can provide high durability for the In-cell type liquid crystal panel.

[0042] <(Meth)acrylic polymer-functional group-containing monomer> The monomer composition for obtaining the (meth)acrylic polymer contains a functional group-containing monomer. The functional group of the functional group-containing monomer can serve as a crosslinking point for reacting with a crosslinking agent contained in the PSA composition, and the gel fraction of the obtained PSA layer can be adjusted to an appropriate range.

[0043] Examples of the functional group-containing monomer include a hydroxyl group-containing monomer and an acid group-containing monomer.

[0044] The hydroxyl group-containing monomer is not particularly limited as long as it is a monomer having a hydroxyl group and a polymerizable group. Examples of the polymerizable group include groups having a polymerizable double bond such as a vinyl group and a (meth)acryloyl group.

[0045] Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate.

[0046] The acidic group-containing monomer may include a carboxyl group-containing monomer, for example, (meth)acrylic acid, β-carboxyethyl (meth)acrylate, 5-carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, methacrylic acid or the like carboxyl group-containing monomers or their anhydrides (maleic anhydride, etc.).

[0047] The functional group-containing monomer may contain 0.1% by mass or more and 15% by mass or less in the monomer composition. For example, the functional group-containing monomer may contain 0.3% by mass or more, 0.5% by mass or more, 0.8% by mass or more, or 1.0% by mass or more in the monomer composition, and may contain 10% by mass or less, 8.0% by mass or less, 5.0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, or 1.5% by mass or less. For example, the functional group-containing monomer may contain 0.3% by mass or more and 5.0% by mass or less, or 0.5% by mass or more and 2.0% by mass or less in the monomer composition.

[0048] <(Meth)acrylic acid polymer-other monomer components> The monomer composition for obtaining the (meth)acrylic polymer may further contain other monomers in addition to the (meth)acrylate alkoxyalkyl ester and the functional group-containing monomer within a range in which the advantageous effects of the present invention can be obtained.

[0049] Examples of other monomers include (meth)acrylic acid alkyl esters having an alkyl group with a carbon number of 1 to 20. The alkyl group of the (meth)acrylic acid alkyl ester is linear or branched, and the carbon number of the alkyl group can be in the range of 1 to 20, 1 to 10, or 2 to 8.

[0050] Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, n-stearyl (meth)acrylate, and isostearyl (meth)acrylate.

[0051] In addition, as other monomers, for example, nitrogen-containing monomers such as (meth)acrylamide, N-(meth)acryloylpiperidine, N-vinylpyrrolidone, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate, and N,N-diethylaminoethyl methacrylate; (meth)acrylates having an aromatic ring group such as benzyl (meth)acrylate, 2-naphthyl acrylate, and phenoxyethyl acrylate; styrene-based monomers such as styrene, α-methylstyrene, o-methylstyrene, and p-methylstyrene; carboxylic acid vinyl esters such as vinyl acetate; macromonomers containing a vinyl (meth)acryloyl group, etc.

[0052] Other monomers can contain more than 0 mass %, more than 5 mass %, more than 10 mass %, or more than 15 mass % in the monomer composition, and can contain less than 49 mass %, less than 48 mass %, less than 40 mass %, less than 30 mass %, less than 20 mass %, less than 10 mass %, less than 5.0 mass %, less than 3.0 mass %, or less than 1.0 mass %. For example, other monomers can contain more than 0 mass % and less than 48 mass %, or more than 0 mass % and less than 10 mass % in the monomer composition. According to the research of the inventors, it is known that when the content of other monomers is many, there is also a situation that the various physical properties of the obtained adhesive layer are adversely affected. Therefore, other monomers can be substantially not contained in the monomer composition.

[0053] In this specification, "substantially free of" means that the component may be contained within a range that does not impair the advantageous effects of the present invention. For example, substantially free of the component in the composition may mean that the component is less than 0.50 mass %, less than 0.30 mass %, less than 0.20 mass %, less than 0.10 mass %, or less than 0.05 mass % in the composition.

[0054] <(Meth)acrylic acid polymer-polymerization initiator> The (meth)acrylic polymer can be polymerized by a known polymerization initiator. As the polymerization initiator, an organic peroxide or azo compound that can be used in free radical polymerization can be used. Specifically, as the polymerization initiator, organic peroxides such as tert-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, and benzoyl peroxide, and azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, and 2,2'azobis-4-methoxy-2,4-dimethylvaleronitrile can be cited.

[0055] The polymerization initiator can be used in an amount of 0.01 parts by mass to 2.0 parts by mass, or 0.1 parts by mass to 1.0 parts by mass, based on 100 parts by mass of the total monomer components.

[0056] <(Meth)acrylic polymer-solvent> The monomer composition may contain a solvent depending on the polymerization method. For example, when a polymer is obtained by solution polymerization, an organic solvent capable of dissolving the monomer components may be used.

[0057] Specifically, as organic solvents, for example, aromatic hydrocarbons such as benzene, toluene, ethylbenzene, tert-butylbenzene, xylene, and aromatic naphtha; aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, dipentene, petroleum spirit, naphtha, and turpentine; esters such as ethyl acetate, n-butyl acetate, n-amyl acetate, and methyl benzoate; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; glycol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; and alcohols such as methanol, ethanol, and tert-butyl alcohol can be used alone or in combination of two or more. For example, it is particularly preferred to use organic solvents such as esters and ketones that are difficult to cause chain transfer during the polymerization reaction. In particular, ethyl acetate, methyl ethyl ketone, acetone, and the like can be used from the perspective of the solubility of the monomer components and the ease of the polymerization reaction.

[0058] <(Meth)acrylic acid polymer-Other components> The monomer composition may contain other components within the range that does not impair the advantageous effects of the present invention. For example, the monomer component may contain a chain transfer agent, and may contain an emulsifier, a dispersant, a dispersion medium, etc. depending on the polymerization method.

[0059] Examples of the chain transfer agent include cyanoacetic acid, bromoacetic acid, or their alkyl esters having 1 to 8 carbon atoms; aromatic compounds such as anthracene, phenanthrene, and fluorene; aromatic nitro compounds such as p-nitroaniline, nitrobenzene, and p-nitrobenzoic acid; benzoquinone derivatives such as benzoquinone and 2,3,5,6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; halogenated hydrocarbons such as carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, and 3-chloro-1-propylene; aldehydes such as trichloroacetaldehyde and furfural; alkyl mercaptans having 1 to 18 carbon atoms; aromatic mercaptans such as thiophenol and toluene mercaptan; thioglycolic acid and its alkyl esters having 1 to 10 carbon atoms; hydroxyalkyl mercaptans having 1 to 12 carbon atoms; and terpenes such as pinene and terpinolene.

[0060] <(Meth)acrylic acid polymer-polymerization method> The polymerization method of the (meth)acrylic polymer is not particularly limited, and the polymer may be obtained by known methods such as solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, etc. When the polymer is used to produce the adhesive composition, it is preferably obtained by solution polymerization because the processing step is relatively simple and can be carried out in a short time.

[0061] <Cross-linking agent> The adhesive composition may contain a crosslinking agent. By containing a crosslinking agent, the gel fraction of the obtained adhesive layer can be within an appropriate range. As the crosslinking agent, an isocyanate crosslinking agent known in the art can be used, for example, a crosslinking agent having two or more isocyanate groups or isocyanurate groups and a hydrocarbon group with a carbon number of 1 to 20 optionally containing an oxygen atom can be used.

[0062] Specifically, as the isocyanate crosslinking agent, there is no particular limitation as long as it is a crosslinking agent that can crosslink with a functional group-containing monomer at room temperature or under heating, and examples thereof include isocyanate monomers such as xylylene diisocyanate, toluene diisocyanate, chlorophenyl diisocyanate, and hexamethylene diisocyanate, and isocyanate compounds and isocyanurates thereof that undergo addition reactions with divalent or higher alcohol compounds such as trimethylolpropane. In addition, as the isocyanate crosslinking agent, urethane prepolymer-type isocyanates that undergo addition reactions with isocyanate compounds and known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and the like can also be cited.

[0063] In addition, as a crosslinking agent, an epoxy crosslinking agent can be used. As an epoxy crosslinking agent, an epoxy compound having two or more epoxy groups in one molecule can be used, specifically, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl meta-xylylene diamine, N,N,N',N'-tetraglycidylaminophenylmethane, triglycidyl isocyanurate, meta-N,N-diglycidylaminophenyl glycidyl ether, N,N-diglycidyl toluidine, and N,N-diglycidyl aniline can be used.

[0064] In addition, as a crosslinking agent, a metal chelate crosslinking agent can be used. As a metal chelate crosslinking agent, a compound in which an alkoxide, acetylacetone, ethyl acetoacetate, etc. are coordinated to a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium, etc. can be used. Specifically, aluminum isopropoxide, aluminum sec-butyrate, ethyl acetoacetate / aluminum diisopropoxide, aluminum triethylacetoacetate, aluminum triacetylacetonate can be used.

[0065] In the adhesive composition, the crosslinking agent may be contained in an amount of 0.01 parts by mass or more, 0.1 parts by mass or more, 0.2 parts by mass or more, 0.3 parts by mass or more, or 0.5 parts by mass or more, and may be contained in an amount of 3.0 parts by mass or less, 1.0 parts by mass or less, 0.5 parts by mass or less, or 0.2 parts by mass or less. For example, the crosslinking agent may be contained in an amount of 0.01 parts by mass or more and 3.0 parts by mass or less, or 0.1 parts by mass or more and 0.5 parts by mass or less, based on 100 parts by mass of the (meth)acrylic acid polymer.

[0066] For the adhesive layer formed by the adhesive composition, the gel fraction measured by the method described in the examples after the crosslinking agent crosslinks the polymer may be 50% or more, 55% or more, 60% or more, 62% or more, 64% or more, 66% or more, or 68% or more, and may be 90% or less, 85% or less, 80% or less, 75% or less, or 70% or less. For example, the gel fraction of the adhesive layer may be 50% or more and 90% or less, or 62% or more and 90% or less.

[0067] <Antistatic Agent> The pressure-sensitive adhesive composition may contain an antistatic agent containing an ionic compound. It is believed that the pressure-sensitive adhesive composition containing the antistatic agent can achieve high antistatic performance because the oxygen atom of the alkoxyalkyl group of the (meth)acrylic polymer is coordinated to the ionic group contained in the antistatic agent.

[0068] Examples of the antistatic agent include ionic compounds, surfactants, etc. The ionic compound includes cations and anions, and may be solid or liquid at 25°C.

[0069] Examples of cations constituting the ionic compound include inorganic cations and organic cations. Examples of inorganic cations include Li ＋ 、Na ＋ , K ＋ Examples of the organic cation include pyridinium cations, piperidinium cations, pyrrolidinium cations, pyrrolinium cations, pyrrole cations, imidazolium cations, tetrahydropyrimidinium cations, dihydropyrimidinium cations, pyrazolium cations, pyrazolinium cations, tetraalkylammonium cations, trialkylsulfonium cations, tetraalkylphosphonium cations, and derivatives thereof.

[0070] The anion constituting the ionic compound is not particularly limited as long as it can form an ionic compound by ion bonding with the above-mentioned cation, and examples thereof include F － , Cl － Br － ,I － 、AlCl4 － 、Al2Cl7 － 、BF4 － PF6 － 、SCN － 、ClO4 － 、NO3 － 、CH3COO － CF3COO － 、CH3SO3 － CF3SO3 － 、(CF3SO2)2N － 、(F2SO2)2N － 、(CF3SO2)3C － 、AsF6 － 、SbF6 － 、NbF6 － 、TaF6 － 、F(HF)n － 、(CN)2N － 、C4F9SO3 － 、(C2F5SO2)2N － 、C3F7COO － and (CF3SO2)(CF3CO)N － .

[0071] As the ionic compound, which is composed of these cations and anions, specifically, there can be mentioned lithium bis(trifluoromethanesulfonyl)imide, lithium bis(difluorosulfonyl)imide, lithium tris(trifluoromethanesulfonyl)methane, potassium bis(trifluoromethanesulfonyl)imide, potassium bis(difluorosulfonyl)imide, 1-ethylpyridinium hexafluorophosphate, 1-butyl-4-pyridinium hexafluorophosphate, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium hexafluorophosphate, 4-Methylpyridinium bis(fluorosulfonyl)imide, 1-octyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide, (N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, butyltrimethylammonium bis(trifluoromethanesulfonyl)imide, 1-octylpyridinium fluorophosphonium imide, 1-octyl-3-methylpyridinium, trifluorosulfonium imide.

[0072] As the above-mentioned surfactant, any one of a nonionic surfactant, a cationic surfactant, an anionic surfactant and an amphoteric surfactant can be used. In addition, as an antistatic agent, conductive polymers, conductive carbon, ammonium chloride, aluminum chloride, cupric chloride, ferric chloride, ammonium sulfate, etc. can be used.

[0073] In the adhesive composition, the antistatic agent may be contained in an amount of 0.1 parts by mass or more, 0.3 parts by mass or more, 0.5 parts by mass or more, 1.0 parts by mass or more, or 2.0 parts by mass or more, and may be contained in an amount of 15 parts by mass or less, 10 parts by mass or less, 5.0 parts by mass or less, 3.0 parts by mass or less, or 2.0 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer. For example, the antistatic agent may be contained in an amount of 0.1 parts by mass or more and 10 parts by mass or less, or 0.5 parts by mass or more and 5.0 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer.

[0074] <Silane coupling agent> The adhesive composition may contain a silane coupling agent. The adhesive composition containing a silane coupling agent can well maintain the bonding between the adherend and the adhesive layer.

[0075] As the silane coupling agent, any silane coupling agent known in the art can be used, for example, silicon compounds containing polymerizable unsaturated groups such as vinyl trimethoxysilane; silicon compounds having epoxy structures such as 3-glycidyloxypropyl trimethoxysilane; silicon compounds containing amino groups such as 3-aminopropyl trimethoxysilane; 3-chloropropyl trimethoxysilane; oligomer type silane coupling agents. Among these, silane coupling agents having functional groups reactive with functional groups contained in (meth) acrylic polymers or their monomer components are particularly preferred in that the adhesive layer is not easily peeled off from the adherend in a high humidity and heat environment.

[0076] In the adhesive composition, the silane coupling agent may be contained in an amount of 0.05 mass part or more, 0.1 mass part or more, 0.2 mass part or more, 0.3 mass part or more, or 0.5 mass part or more, and may be contained in an amount of 1.0 mass part or less, 0.5 mass part or less, 0.3 mass part or less, or 0.2 mass part or less. For example, the silane coupling agent may be contained in an amount of 0.05 mass part or more and 1.0 mass part or less, or 0.1 mass part or more and 0.5 mass part or less, relative to 100 mass parts of the (meth)acrylic polymer.

[0077] <Solvent> The pressure-sensitive adhesive composition may contain a solvent in order to adjust coating properties. The type of the solvent may be the same as the polymerization solvent used for polymerizing the (meth)acrylic polymer.

[0078] By making the adhesive composition contain a solvent, the solid content concentration can be adjusted. The solid content concentration of the adhesive composition can be 10% by mass or more, 12% by mass or more, 14% by mass or more, or 16% by mass or more, and can be 40% by mass or less, 30% by mass or less, 20% by mass or less, or 18% by mass or less. For example, the solid content concentration of the adhesive composition can be 10% by mass or more and 30% by mass or less, or 12% by mass or more and 20% by mass or less.

[0079] In addition to the above components, the adhesive composition may contain components selected from ultraviolet absorbers, antioxidants, tackifying resins, plasticizers, defoamers, fillers, stabilizers, softeners, and wettability regulators within a range that does not impair the effects of the present invention.

[0080] <Laminated body> In one embodiment, the present invention is a laminate. The laminate comprises a first component, a second component, and an adhesive layer joining them, wherein the adhesive layer is formed by the above-mentioned adhesive composition. The adhesive layer can be the same adhesive layer as the adhesive layer of the In-cell type liquid crystal panel, and can be obtained in the same manner as when the adhesive layer is formed.

[0081] Figure 2 It is a cross-sectional view schematically showing an example of a laminated body.

[0082] like Figure 2 As shown, the laminate 100 includes a glass substrate 10 as a first component, a polarizing film 30 as a second component, and an adhesive layer 20 for bonding them. The polarizing film 30 includes a polycycloolefin film 32, a polyvinyl alcohol film 34 on the polycycloolefin film 32, and a TAC film 36 on the polyvinyl alcohol film 34. The glass substrate 10 and the polycycloolefin film 32 are bonded by the adhesive layer 20.

[0083] Figure 3 It is a cross-sectional view schematically showing another example of the laminated body.

[0084] like Figure 3 As shown, the laminate 200 includes a glass substrate 10 as a first component, a polycycloolefin film (phase difference film) 32 as a second component, and a polarizing film 130 as a third component, and includes adhesive layers 20 and 22 that join them. More specifically, the polycycloolefin film 32 and the polarizing film 130 are joined by the adhesive layer 20. In addition, the glass substrate 10 and the polycycloolefin film 32 are joined by the adhesive layer 22. The polarizing film 130 has a layer 38 of a polycycloolefin film (second polycycloolefin film) or a TAC film, a polyvinyl alcohol film 34 on the layer 38, and a TAC film 36 on the polyvinyl alcohol film 34. The polycycloolefin film (first polycycloolefin film) 32 and the layer (second polycycloolefin film) 38 are joined by the adhesive layer 20.

[0085] Figure 2 and Figure 3 The adhesive layers 20 and 22 are formed on the surface of the adherend. As a method for forming the adhesive composition on the surface of the adherend, for example, a transfer method can be mentioned, in which the adhesive composition is applied on the surface of a release film (spacer) with good smoothness, the coated film is dried, and then the coated film is transferred to the surface of a specific resin film.

[0086] The laminate can be used, for example, in an image display device, particularly a liquid crystal display device. More specifically, the laminate can be used, for example, in an image display device for a touch panel. In this case, the glass substrate included in the laminate can be a glass substrate for a liquid crystal display device.

[0087] The image display device may be, for example, a TFT (Thin Film Transistor) liquid crystal display device used in a liquid crystal television, a computer monitor, a mobile phone, a tablet computer, or the like.

[0088] The present invention is further described in detail by the following examples, but the present invention is not limited thereto.

[0089] Example <Manufacturing example> <Example 1> In a flask equipped with a stirring device, a nitrogen inlet pipe, a thermometer, and a reflux cooling tube, 98.8 parts by mass of 2-methoxyethyl acrylate, 1 part by mass of 4-hydroxybutyl acrylate, 0.2 parts by mass of acrylic acid, and 100 parts by mass of ethyl acetate were added. Then, while introducing nitrogen into the flask, the contents were heated to 65°C. Next, 0.05 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added to the flask fully substituted with nitrogen while stirring. The temperature of the contents in the flask was maintained at 65°C while reacting for 6 hours.

[0090] To the reaction mixture after 6 hours had passed, 300 parts by mass of ethyl acetate was further added to obtain a solution containing a (meth)acrylic acid-based polymer. The Mw of the obtained (meth)acrylic acid-based polymer measured by GPC was 1.9 million.

[0091] A crosslinking agent, an antistatic agent, and a silane coupling agent were mixed with 100 parts by mass of the solid content of the obtained solution containing a (meth)acrylic polymer in the amounts shown in Table 1 in terms of solid content, and then the mixture was fully mixed to obtain an adhesive composition. Here, the solid content refers to all components after removing the organic solvent from the adhesive composition.

[0092] <Examples 2 to 18, Comparative Examples 1 and 2> The adhesive compositions of Examples 2 to 18 and Comparative Examples 1 to 2 were obtained in the same manner as in Example 1 except that the components used were changed to those shown in Table 1. The amount of ethyl acetate initially charged was changed to 120 parts in Example 12, 150 parts in Example 13, and 80 parts in Example 14 for the reactions.

[0093] <Adhesive Sheet> The adhesive composition obtained in the examples and comparative examples was applied to the release-treated PET film at a liquid temperature of 25°C using a doctor blade so that the film thickness after drying was 25 μm. Thereafter, it was dried at 90°C for 3 minutes, and a release-treated PET film was further attached to the adhesive layer on the opposite side of the release-treated PET film. Then, it was left to stand at 50°C for 3 days to obtain an adhesive sheet.

[0094] <Polarizing film with adhesive layer> On the peeled PET film, the adhesive composition obtained in the examples and comparative examples was applied using a doctor blade at a liquid temperature of 25°C so that the film thickness after drying was 25μm. Thereafter, it was dried at 90°C for 3 minutes, and the adhesive layer on the opposite side of the peeled PET film was attached to the polarizing film (COP film 40μm / PVA film 20μm / TAC film 40μm) so that the adhesive layer was in contact with the COP film surface of the polarizing film. And, it was left to stand at 50°C for 3 days to obtain a polarizing film with an adhesive layer.

[0095] <Test method> <Gel fraction> Collect about 0.1g of adhesive from the adhesive sheet into a sampling bottle. Add 30mL of ethyl acetate to the sampling bottle and shake for 4 hours. Filter the contents of the sample bottle with a 200-mesh stainless steel wire mesh, and dry the residue on the wire mesh at 90°C for 2 hours to determine the dry weight. Calculate the gel fraction of the adhesive using the following formula.

[0096] Gel fraction (%) = (dry weight / adhesive collection weight) × 100 (%) <Wet heat durability> The polarizing film with the adhesive layer is cut into a size of 160 mm (MD direction) × 90 mm (TD direction) to prepare a test piece. The release film (peel-treated PET film) is peeled off from the test piece, and the adhesive layer is bonded to the glass substrate of the In-cell type liquid crystal unit on the visual side of the In-cell type liquid crystal unit. The obtained laminate is kept in an autoclave adjusted to 50°C / 5 atmospheric pressure for 20 minutes to prepare a test plate. The test plate is placed at a temperature of 85°C and 85% RH for 24 hours, and the appearance defects such as blistering of the adhesive layer of the test plate, cracking of the test plate, and peeling of the adhesive layer are visually observed and evaluated according to the following criteria.

[0097] ◎: No problem 〇: Slight defects in appearance confirmed, but no problem in actual use △: Appearance defects were confirmed, but the product can be used in practice. ×: Appearance defects were confirmed, but the product cannot be used in practice. <Whitening resistance> The polarizing film with an adhesive layer was cut into a size of 160 mm (MD direction) × 90 mm (TD direction) to prepare a test piece, which was left at 85°C 85% RH for 24 hours, and the whitening of the adhesive layer was visually observed and evaluated according to the following criteria.

[0098] ○: No whitening △: Slight turbidity was observed, but it can be actually used ×: Whitening <Surface resistivity> The release film (release-treated PET film) was peeled off from the adhesive layer of the adhesive layer-attached polarizing film, and the surface resistivity a of the adhesive layer was measured at an applied voltage of 1000 V in accordance with JIS-K-6911 using a resistivity meter (Hiresta UX MCP-HT800, manufactured by Mitsubishi Chemical Analytech).

[0099] In addition, another polarizing film with an adhesive layer was placed in a humidified environment of 85°C and 85% RH for 24 hours, and then dried at 40°C for 1 hour. The release film (peel-treated PET film) was peeled off from the adhesive layer and the surface resistivity b was measured. The surface resistivity change ratio (b / a) was calculated from the surface resistivity a and the surface resistivity b.

[0100] <Polarization> The polarizing film with the adhesive layer was cut into a size of 20 mm (MD direction) × 30 mm (TD direction) to prepare two test pieces. The release film (PET film with a release treatment) was peeled off from the test piece, and a spectrophotometer V7100 (manufactured by JASCO Corporation) with an integrating sphere was used to perform visibility correction in the visible light region with a C light source and a 2° viewing angle in accordance with JIS Z8722 (Method for measuring color of an object). For this sample, the transmittance of light in the parallel Nicol state T∥ (%) and the transmittance of light in the orthogonal Nicol state T⊥ (%) were measured, and the degree of polarization was calculated by the following formula.

[0101] Polarization degree = {(T∥-T⊥) / (T∥+T⊥)} 1／2 ×100 For the degree of polarization after wet heat treatment, the release film (peeling-treated PET film) was peeled off from the test piece, and the laminate was attached to the visual side of the In-cell liquid crystal unit in such a manner that the adhesive layer was in contact with the transparent substrate of the In-cell liquid crystal unit. The obtained laminate was then kept in an autoclave adjusted to 50°C / 5% air pressure for 20 minutes, and then kept in a humidified environment of 85°C and 85% RH for 24 hours. Next, the polarizing film with the adhesive layer was peeled off from the In-cell liquid crystal unit, and the degree of polarization after wet heat treatment was calculated using the above method.

[0102] <Results> The results are shown in the following table.

[0103]

Table 1

Table 2

[0104] Referring to Examples 8 to 11, it can be seen that when the (meth)acrylic polymer is produced from a monomer containing a large amount of alkoxyalkyl (meth)acrylate, it is good in terms of wet heat durability, surface resistance, etc. If the comparative example 1 is further included, the advantageous effect of the alkoxyalkyl (meth)acrylate can be particularly understood. Comparative Example 2 has no problem in terms of wet heat durability, etc. due to the small amount of antistatic agent, but the surface resistance is very high.

[0105] Description of Reference Numerals 1 In-cell LCD panel 10a First transparent substrate 10b Second transparent substrate 20a First adhesive layer 20b Second adhesive layer 30a First polarizing film 30b Second polarizing film 4 Liquid crystal layer 5 Touch sensing function part 10 Glass Substrate 20, 22 Adhesive layer 30, 130 polarizing film 32 Phase difference film (polycycloolefin film) 34 Polyvinyl alcohol (PVA) film 36 TAC film 38 Polycycloolefin film or TAC film 100, 200 laminates.

Claims

1. An In-cell type liquid crystal panel, comprising a first polarizing film, a first transparent substrate, and an adhesive layer disposed between the first polarizing film and the first transparent substrate, The adhesive layer is formed of an adhesive composition containing a (meth)acrylic polymer, a crosslinking agent, and an antistatic agent. The (meth)acrylic polymer is a polymer of a monomer composition containing more than 50% by mass of an alkoxyalkyl (meth)acrylate and 0.1 to 15% by mass of a functional group-containing monomer.

2. The In-cell type liquid crystal panel according to claim 1, wherein: The monomer composition contains 80% by mass or more of an alkoxyalkyl (meth)acrylate.

3. The In-cell type liquid crystal panel according to claim 1, wherein: The (meth)acrylic acid-based polymer has a weight average molecular weight of 1.2 million or more.

4. The In-cell type liquid crystal panel according to claim 1, wherein: The change ratio b / a of the surface resistivity of the adhesive layer before and after the durability test is less than 5.0, wherein a is the surface resistivity of the adhesive layer just after the release film is peeled off, and b is the surface resistivity of the adhesive layer just after the release film is peeled off after the polarized film with the adhesive layer affixed with the release film is placed in a humidified environment of 85°C×85%RH for 24 hours and further dried at 40°C for 1 hour.

5. The In-cell type liquid crystal panel according to claim 1, wherein: The polarization degree after the durability test is above 99.0%. The polarization degree after the durability test is measured after the polarizing film with the adhesive layer is attached to the In-cell liquid crystal unit, kept in an autoclave adjusted to 50°C / 5 pressure for 20 minutes, and then placed in a humidified environment of 85°C and 85% RH for 24 hours.

6. The In-cell liquid crystal panel according to any one of claims 1 to 5, comprising An in-cell type liquid crystal unit comprises a liquid crystal layer, a first transparent substrate and a second transparent substrate sandwiching the liquid crystal layer on both sides, and a touch sensing functional part between the first transparent substrate and the second transparent substrate. The device further comprises a first polarizing film disposed on the viewing side of the in-cell type liquid crystal unit, a second polarizing film disposed on the opposite side to the viewing side, and the adhesive layer provided between the first polarizing film and the first transparent substrate of the in-cell type liquid crystal unit.

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