Resin film with pressure-sensitive adhesive and optical laminate including same

Abstract

The object of the present invention is to provide an adhesive-attached resin film that uses a resin film with high ion permeability as an adherend for the adhesive, and that can maintain stable antistatic properties over a long period of time, and further to provide an optical laminate by laminating the adhesive-attached resin film to a glass substrate, a typical example of which is a liquid crystal cell. [Solution] An adhesive-backed resin film having a resin film and an adhesive layer provided on at least one side of the resin film, wherein the adhesive layer is composed of a resin and an adhesive containing an ionic compound whose solubility in water at 60°C is 0.4 g / 100 g or less, and the resin film is immersed in a 50 mass % aqueous potassium iodide solution for 4.5 hours in an atmospheric atmosphere of 23°C and 55% RH, washed with water for 15 seconds, and dried in a dark place for 15 hours, after which the maximum change in the amount of light absorbed at wavelengths of 355 to 365 nm compared to before the treatment is 5% or more.

Description

[Technical Field]

[0001] The present invention relates to a resin film having a pressure-sensitive adhesive layer formed thereon, i.e., a pressure-sensitive adhesive-attached resin film. The present invention also relates to an optical laminate for a liquid crystal display using the resin film having a pressure-sensitive adhesive layer formed thereon. [Background technology]

[0002] When a liquid crystal display device is charged with static electricity, the display function may be impaired. Therefore, it is desirable that components such as polarizing plates constituting a liquid crystal display device have an antistatic function. For example, a protective film, which is a type of resin film, is laminated on one or both sides of a polarizing film to form a polarizing plate, and the antistatic function may be imparted to the pressure-sensitive adhesive layer. Polarizing plates are generally distributed in a state in which an adhesive layer is formed on at least one surface of the protective film, and a release film is attached to the adhesive layer.

[0003] One known method for imparting antistatic properties to a pressure-sensitive adhesive is to blend an antistatic agent into the adhesive. Patent Document 1 describes that by incorporating a specific ionic compound that becomes solid at room temperature (25°C) into the adhesive, a pressure-sensitive adhesive resin film that does not change over time even when a polarizing plate coated with the adhesive is left standing for a long period of time and has excellent antistatic properties and durability can be obtained.

[0004] However, some resin films that are adherends for pressure-sensitive adhesives have high ion permeability and allow ionic compounds to easily permeate and migrate through them, and for such adherends, even when the ionic compounds described in the above patent documents are added to the pressure-sensitive adhesive, the desired antistatic properties may not be maintained for a long period of time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-79205 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to provide an adhesive-attached resin film that uses a resin film with high ion permeability as an adherend for the adhesive, and that can maintain stable antistatic properties over a long period of time, and further to provide an optical laminate in which the adhesive-attached resin film is bonded to a glass substrate, a typical example of which is a liquid crystal cell. [Means for solving the problem]

[0007] The inventors conducted extensive research to solve this problem for polarizing plates that use a resin film with high ion permeability as the transparent protective film that is the substrate of the adhesive, and as a result, they discovered that by incorporating a specific ionic compound into the adhesive as an antistatic agent, it is possible to obtain a resin film with an adhesive that can stably maintain antistatic properties for a long period of time. Furthermore, it has been found that the pressure-sensitive adhesive resin film obtained by the present invention has excellent durability and reworkability when it is stuck to glass to obtain an optical laminate.

[0008] The present invention provides the following preferred embodiments [1] to [6]. [1] A resin film with a pressure-sensitive adhesive, comprising a resin film and a pressure-sensitive adhesive layer provided on at least one side of the resin film, the pressure-sensitive adhesive layer is composed of a resin and a pressure-sensitive adhesive containing an ionic compound having a solubility in water at 60°C of 0.4 g / 100 g or less, The resin film is immersed in a 50% by mass aqueous solution of potassium iodide for 4.5 hours in an atmospheric environment of 23°C and 55% RH, washed with water for 15 seconds, and then dried in a dark place for 15 hours, after which the maximum change in the amount of absorbance of light at a wavelength of 355 to 365 nm compared to before the treatment is 5% or more. [2] A resin film with a pressure-sensitive adhesive, comprising a resin film and a pressure-sensitive adhesive layer provided on at least one side of the resin film, The pressure-sensitive adhesive layer comprises a resin and a compound represented by the following formula (I): [ka] [In the formula, R1 is H or a linear alkyl group having 1 to 3 carbon atoms, and R2 is a linear alkyl group having 5 to 14 carbon atoms or an aralkyl group having 7 to 13 carbon atoms.] The adhesive comprises an ionic compound which is a pyridinium salt represented by the formula: The resin film is immersed in a 50% by mass aqueous solution of potassium iodide for 4.5 hours in an atmospheric environment of 23°C and 55% RH, washed with water for 15 seconds, and then dried in a dark place for 15 hours, after which the maximum change in the amount of absorbance of light at a wavelength of 355 to 365 nm compared to before the treatment is 5% or more. [3] The adhesive resin film according to [1] or [2], wherein the adhesive contains 0.05 to 8 parts by mass of the ionic compound per 100 parts by mass of the resin. [4] The pressure-sensitive adhesive resin film according to any one of [1] to [3] above, wherein the resin is a (meth)acrylic resin. [5] The pressure-sensitive adhesive resin film according to any one of [1] to [4] above, wherein the resin film has a thickness of 10 to 200 μm. [6] An optical laminate comprising the pressure-sensitive adhesive resin film according to any one of [1] to [5] above, and a glass substrate laminated on the pressure-sensitive adhesive layer side. [Effects of the Invention]

[0009] The pressure-sensitive adhesive resin film of the present invention can exhibit stable antistatic properties over a long period of time, even when a resin film with high ion permeability is used as an adherend for the pressure-sensitive adhesive. Furthermore, when the pressure-sensitive adhesive resin film of the present invention is laminated to glass, the optical laminate can exhibit excellent durability. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a layer structure of an optical laminate according to one embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically illustrating an example of a layer structure of an optical laminate according to one embodiment of the present invention. [Figure 3] 1 is a cross-sectional view schematically illustrating an example of a layer structure of an optical laminate according to one embodiment of the present invention. [Figure 4] 1 is a cross-sectional view schematically illustrating an example of a layer structure of an optical laminate according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The adhesive-backed resin film of the present invention comprises a resin film and an adhesive layer on at least one side of the resin film, the adhesive layer being composed of a resin and an adhesive containing a specific ionic compound.

[0012] <Adhesive layer> In the present invention, the pressure-sensitive adhesive layer is provided on at least one side of the resin film and is composed of a pressure-sensitive adhesive. The pressure-sensitive adhesive contains a resin and the above-mentioned ionic compound. Each component constituting the pressure-sensitive adhesive in the present invention will be described below.

[0013] [resin] In the present invention, the type of resin contained in the pressure-sensitive adhesive is not particularly limited, and examples thereof include (meth)acrylic resins, silicone resins, urethane resins, and rubber. The resins can be used alone or in combination. Among these, it is preferable to use a (meth)acrylic resin (A) as the resin, since functionality can be easily imparted to the pressure-sensitive adhesive by selecting the type of monomer introduced into the resin. The structural units constituting the (meth)acrylic resin (A) are also not limited. Examples of the (meth)acrylic resin (A) include polymers primarily composed of structural units derived from a (meth)acrylic acid ester represented by the following formula (II) (hereinafter also referred to as "monomer (II)"). In the present invention, the term "polymer primarily composed of structural units derived from monomer (II)" means that the structural units derived from monomer (II) account for preferably 40% by mass or more, more preferably 60% by mass or more, for example 80% by mass or more, of the total structural units constituting the polymer. In this case, the structural units derived from the monomer (II) are contained in an amount of usually 100% by mass or less, preferably 90% by mass or less, based on the total structural units constituting the polymer.

[0014] [ka]

[0015] In formula (II), R3 is a hydrogen atom or a methyl group, and R4 is an alkyl or aralkyl group usually having 14 or less carbon atoms, preferably 10 or less carbon atoms.

[0016] In one embodiment of the present invention, the (meth)acrylic resin (A) may contain, in addition to structural units derived from (meth)acrylic acid esters, other structural units, particularly structural units derived from monomers having polar functional groups, preferably structural units derived from (meth)acrylic acid compounds having polar functional groups. Examples of polar functional groups include carboxyl groups, hydroxyl groups, amino groups, and heterocyclic groups such as epoxy rings. Examples of (meth)acrylic acid compounds having polar functional groups include (meth)acrylic acid, 2-(dimethylamino)ethyl acrylate, 2-hydroxyethyl (meth)acrylate, and glycidyl acrylate. Furthermore, the (meth)acrylic resin (A) may contain structural units derived from monomers other than the monomer (II) that do not have polar functional groups. Suitable structural units (monomers) include structural units derived from monomers having one olefinic double bond and at least one aromatic ring in the molecule, preferably structural units derived from (meth)acrylic acid compounds having aromatic rings. In this specification, (meth)acrylic acid means either acrylic acid or methacrylic acid, and the "(meth)" in (meth)acrylate and the like has the same meaning.

[0017] More specific examples of the monomer (II) in which R4 is an alkyl group include linear acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, n-octyl acrylate, and lauryl acrylate; branched acrylates such as isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; linear methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, and lauryl methacrylate; and branched methacrylates such as isobutyl methacrylate, 2-ethylhexyl methacrylate, and isooctyl methacrylate.

[0018] Among these, n-butyl acrylate is preferred, and specifically, it is preferred that n-butyl acrylate accounts for 50 mass% or more of all structural units (monomers) constituting the (meth)acrylic resin (A) and that the above-mentioned requirement for the monomer (II) is satisfied.

[0019] Among the monomers (II), specific examples of the monomers in which R4 is an aralkyl group include benzyl acrylate and benzyl methacrylate.

[0020] These monomers (II) can be used alone or in combination.

[0021] The alkyl group or aralkyl group constituting R4 in the formula (II) is a group in which the hydrogen atom is replaced by -O-(C2H4O) n It may be substituted with -R5.

[0022] In the formula (II), the hydrogen atom of the alkyl group or aralkyl group constituting R4 is a group -O-(C2H4O) n When substituted with -R5, n is preferably 0 or an integer of 1 to 4, and more preferably 0, 1, or 2. R5 is an alkyl group or aryl group having 12 or less carbon atoms, and may be linear or branched as long as the alkyl group has 3 or more carbon atoms. Examples of aryl groups constituting R5 include phenyl and naphthyl, as well as tolyl, xylyl, phenyl substituted with a nuclear alkyl group including ethylphenyl, and biphenylyl (or phenylphenyl). It is particularly preferable that R5 be any of these aryl groups.

[0023] In formula (II), R4 is an alkyl group or an aralkyl group, and a hydrogen atom of the alkyl group or aralkyl group of R4 is a group -O-(C2H4O) nSpecific examples of the (meth)acrylic acid ester substituted with -R5 include alkoxyalkyl-, aryloxyalkyl-, or aryloxyethoxyalkyl-esters of acrylic acid such as 2-methoxyethyl acrylate, ethoxymethyl acrylate, 2-phenoxyethyl acrylate, 2-(2-phenoxyethoxy)ethyl acrylate, and 2-(o-phenylphenoxy)ethyl acrylate; and alkoxyalkyl-, aryloxyalkyl-, or aryloxyethoxyalkyl-esters of methacrylic acid such as 2-methoxyethyl methacrylate, ethoxymethyl methacrylate, 2-phenoxyethyl methacrylate, 2-(2-phenoxyethoxy)ethyl methacrylate, and 2-(o-phenylphenoxy)ethyl methacrylate.

[0024] The (meth)acrylic resin (A) in the present invention may contain a structural unit derived from a monomer other than the monomer (II) having no polar functional group. Examples of the monomer other than the monomer (II) having no polar functional group include a (meth)acrylic acid ester monomer having an alicyclic structure in the molecule, a styrene-based monomer, a vinyl-based monomer, a (meth)acrylamide derivative, and a monomer having multiple (meth)acryloyl groups in the molecule.

[0025] (Meth)acrylic acid ester monomers having an alicyclic structure in the molecule will be described. The alicyclic structure is a cycloparaffin structure having typically 5 or more carbon atoms, preferably about 5 to 7. Specific examples of acrylic acid ester monomers having an alicyclic structure include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, trimethylcyclohexyl acrylate, tert-butylcyclohexyl acrylate, α-ethoxycyclohexyl acrylate, and cyclohexylphenyl acrylate. Specific examples of methacrylic acid ester monomers having an alicyclic structure include isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, cyclododecyl methacrylate, methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, and cyclohexylphenyl methacrylate.

[0026] Examples of styrene-based monomers include, in addition to styrene, alkylstyrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; and further, nitrostyrene, acetylstyrene, methoxystyrene, divinylbenzene, and the like.

[0027] Examples of vinyl monomers include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl laurate; vinyl halides such as vinyl chloride and vinyl bromide; vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinylpyridine, vinylpyrrolidone, and vinylcarbazole; conjugated diene monomers such as butadiene, isoprene, and chloroprene; and acrylonitrile, methacrylonitrile, and the like.

[0028] Examples of (meth)acrylamide derivatives include N-methylol (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide, N-(4-hydroxybutyl) (meth)acrylamide, N-(5-hydroxypentyl) (meth)acrylamide, N-(6-hydroxyhexyl) (meth)acrylamide, N-(methoxymethyl) (meth)acrylamide, N-(ethoxymethyl) (meth)acrylamide, and N-(propoxymethyl) (meth)acrylamide. )(meth)acrylamide, N-(butoxymethyl)(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-(3-dimethylaminopropyl)(meth)acrylamide, N-(1,1-dimethyl-3-oxobutyl)(meth)acrylamide, N-[2-(2-oxo-1-imidazolidinyl)ethyl](meth)acrylamide, 2-acryloylamino-2-methyl-1-propanesulfonic acid, etc.

[0029] Examples of monomers having multiple (meth)acryloyl groups in the molecule include monomers having two (meth)acryloyl groups in the molecule, such as 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate; and monomers having three (meth)acryloyl groups in the molecule, such as trimethylolpropane tri(meth)acrylate.

[0030] The monomer constituting the (meth)acrylic resin (A) may be a mixture of two or more types of monomers other than the (meth)acrylic acid ester represented by the formula (II) described above, and / or a monomer having a polar functional group, and the monomer (II) not having a polar functional group.

[0031] The weight-average molecular weight (Mw) of the resin contained in the adhesive, measured by gel permeation chromatography (GPC) in terms of standard polystyrene, is not particularly limited, but is preferably in the range of 500,000 to 2,000,000, and more preferably in the range of 500,000 to 1,800,000. A weight-average molecular weight (Mw) of 500,000 or more in terms of standard polystyrene improves adhesion under high-temperature and high-humidity conditions, tends to reduce the likelihood of lifting or peeling between the glass substrate and the adhesive layer, and also tends to improve reworkability. Furthermore, a weight-average molecular weight of 2,000,000 or less is preferred because the adhesive layer follows the dimensional changes of the resin film attached to the adhesive layer, eliminating the difference in brightness between the periphery and center of the liquid crystal cell and tending to suppress whiteout and color unevenness. The molecular weight distribution, expressed as the ratio Mw / Mn of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is not particularly limited, but is preferably in the range of, for example, approximately 3 to 15.

[0032] The resin contained in the pressure-sensitive adhesive can be produced by various known methods, such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. A polymerization initiator may be used in the production of the resin, and the amount added is about 0.001 to 5 parts by mass per 100 parts by mass of the total of all monomers used in the production of the resin.

[0033] The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator. Examples of the photopolymerization initiator include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone. Examples of the thermal polymerization initiator include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-hydroxymethylpropionitrile); lauryl peroxide. Examples of the polymerization initiator include organic peroxides such as tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, and (3,5,5-trimethylhexanoyl)peroxide; and inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide. Redox initiators using a combination of a peroxide and a reducing agent can also be used as the polymerization initiator.

[0034] Among the methods listed above, solution polymerization is preferred as a method for producing the (meth)acrylic resin (A). A specific example of solution polymerization involves mixing the desired monomers and an organic solvent, adding a thermal polymerization initiator under a nitrogen atmosphere, and stirring for 3 to 15 hours at about 40 to 90°C, preferably about 50 to 80°C. To control the reaction, the monomers and the thermal polymerization initiator may be added continuously or intermittently during polymerization, or may be added in a dissolved state in an organic solvent. Examples of organic solvents that can be used include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as propyl alcohol and isopropyl alcohol; and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0035] [Ionic compounds] The adhesive constituting the adhesive-attached resin film of the present invention contains an ionic compound, which is an antistatic agent for imparting antistatic properties to the adhesive layer.

[0036] In one embodiment of the present invention, the ionic compound has a solubility in water at 60°C of 0.4 g / 100 g or less, preferably 0.35 g / 100 g or less, more preferably 0.32 g / 100 g or less, and typically 0.001 g / 100 g or more. When the solubility in water at 60°C of the ionic compound contained in the pressure-sensitive adhesive layer is equal to or less than the above upper limit, the antistatic function of the pressure-sensitive adhesive can be enhanced. Examples of such ionic compounds include pyridinium salts represented by formula (I). In the present invention, solubility refers to the solubility (g) of the ionic compound in 100 g of water at 60°C. In another embodiment of the present invention, there is also provided an adhesive-attached resin film having a resin film and an adhesive layer provided on at least one side of the resin film, wherein the adhesive layer is an adhesive containing a resin and an ionic compound which is a pyridinium salt represented by the following formula (I), and the resin film has a specific maximum change amount.

[0037] The pyridinium salt represented by formula (I) is a chemically stable salt. From the viewpoint of obtaining high antistatic properties, the melting point of the pyridinium salt is preferably 30°C or higher. On the other hand, from the viewpoint of good compatibility with resins, the pyridinium salt preferably has a melting point of 90°C or lower, more preferably 70°C or lower, even more preferably 50°C or lower, and even more preferably lower than 50°C.

[0038] Furthermore, from the viewpoints of durability when attached to glass via an adhesive layer and compatibility in the adhesive, the pyridinium cation, which is the cationic component of the pyridinium salt represented by formula (I), is one in which R2 in formula (I) is a linear alkyl group having 5 to 14 carbon atoms or an aralkyl group having 7 to 13 carbon atoms, for example, a linear alkyl group having 7 to 10 carbon atoms or an aralkyl group having 7 to 10 carbon atoms. Specific examples of this cationic component include those listed below.

[0039] N-pentylpyridinium ion N-hexylpyridinium ion N-heptylpyridinium ion N-octylpyridinium ion N-nonylpyridinium ion N-decylpyridinium ion N-dodecylpyridinium ion N-tridecylpyridinium ion N-tetradecylpyridinium ion N-octyl-2-methylpyridinium ion N-octyl-3-methylpyridinium ion N-octyl-4-methylpyridinium ion N-nonyl-4-methylpyridinium ion N-decyl-4-methylpyridinium ion N-dodecyl-4-methylpyridinium ion N-tridecyl-4-methylpyridinium ion N-tetradecyl-4-methylpyridinium ion N-benzylpyridinium ion N-phenethylpyridinium ion N-benzyl-2-methylpyridinium ion N-benzyl-2-methylpyridinium ion N-benzyl-3-methylpyridinium ion N-benzyl-4-methylpyridinium ion

[0040] If the carbon number of R2 in the pyridinium salt represented by formula (I) is 4 or less, the pyridinium salt will migrate to the highly ion-permeable resin film (e.g., triacetylcellulose substrate) used as the adherend for the pressure-sensitive adhesive, making it difficult to maintain stable antistatic properties over a long period of time. Also, if the carbon number of R2 is 15 or more, the crystallinity of the pyridinium salt will increase, and the compatibility of the pyridinium salt in the pressure-sensitive adhesive will decrease.

[0041] The pyridinium salt represented by formula (I) can be used by appropriately selecting from the combinations of the cation component and the anion component, bis(fluorosulfonyl)imide ion, as described above. Specific examples of such combinations include the following:

[0042] N-Pentylpyridinium bis(fluorosulfonyl)imide N-Hexylpyridinium bis(fluorosulfonyl)imide N-Heptylpyridinium bis(fluorosulfonyl)imide N-Octylpyridinium bis(fluorosulfonyl)imide N-Nonylpyridinium bis(fluorosulfonyl)imide N-Decylpyridinium bis(fluorosulfonyl)imide N-Dodecylpyridinium bis(fluorosulfonyl)imide N-Tetradecylpyridinium bis(fluorosulfonyl)imide N-Dodecyl-4-methylpyridinium bis(fluorosulfonyl)imide N-Tetradecyl-4-methylpyridinium bis(fluorosulfonyl)imide N-Benzylpyridinium bis(fluorosulfonyl)imide N-Benzyl-2-methylpyridinium bis(fluorosulfonyl)imide N-Benzyl-4-methylpyridinium bis(fluorosulfonyl)imide

[0043] The pyridinium salt represented by formula (I) can be obtained by a known method. For example, the pyridinium salt represented by formula (I) can be produced by an ion exchange reaction between an alkylpyridinium bromide represented by formula (III) below (wherein R1 and R2 are as defined above in formula (I)) and a lithium salt Li(FSO2)2N, followed by washing with water to transfer the resulting lithium bromide to the aqueous phase and recovering the organic phase. The pyridinium salt represented by formula (I) can be used alone or in combination of two or more. Of course, examples of the pyridinium salt are not limited to the compounds listed above.

[0044] [ka]

[0045] In the present invention, the pressure-sensitive adhesive contains an ionic compound (e.g., a pyridinium salt represented by formula (I)) in an amount of preferably 0.05 to 8 parts by mass, more preferably 0.1 to 7 parts by mass, and even more preferably 0.3 to 6 parts by mass per 100 parts by mass of the resin contained in the pressure-sensitive adhesive. In the present invention, when the content of the ionic compound in the pressure-sensitive adhesive is equal to or greater than the above-mentioned lower limit, the antistatic properties can be further improved. When the content of the ionic compound in the pressure-sensitive adhesive is equal to or less than the above-mentioned upper limit, durability can be easily maintained and antistatic function can be obtained according to the content, which is economically advantageous and further prevents deterioration in the optical performance of the optical film due to the presence of an excess of the ionic compound.

[0046] [Additives] The adhesive constituting the adhesive layer in the adhesive-backed resin film of the present invention may contain other additives in addition to the resin and the above-mentioned ionic compound, for example, the pyridinium salt represented by formula (1). Examples of other additives include crosslinking agents, silane compounds, crosslinking catalysts, weathering stabilizers, tackifiers, plasticizers, softeners, dyes, pigments, inorganic fillers, organic acids, and organic acid metal salts.

[0047] Furthermore, it is also useful to compound an ultraviolet-curable compound into the adhesive and, after the adhesive layer is formed, to cure it by irradiating it with ultraviolet light, thereby forming a harder adhesive layer.

[0048] (Crosslinking agent) The crosslinking agent that can be contained in the pressure-sensitive adhesive is a compound having at least two functional groups in the molecule that can crosslink the resin contained in the pressure-sensitive adhesive, such as an isocyanate compound, an epoxy compound, a metal chelate compound, and an aziridine compound.

[0049] The isocyanate compound is a compound having at least two isocyanato groups (-NCO) in the molecule, and examples thereof include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Adducts obtained by reacting these isocyanate compounds with polyols such as glycerol and trimethylolpropane, as well as dimers, trimers, and the like of isocyanate compounds, can also be used as crosslinking agents for adhesives. Two or more isocyanate compounds can also be used in combination.

[0050] The epoxy compound is a compound having at least two epoxy groups in the molecule, and examples thereof include bisphenol A epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N,N-diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylylenediamine, etc. Two or more epoxy compounds can also be used in combination.

[0051] Examples of metal chelate compounds include compounds in which acetylacetone or ethyl acetoacetate is coordinated with a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, or zirconium.

[0052] Aziridine compounds are compounds that have at least two three-membered ring skeletons, each consisting of one nitrogen atom and two carbon atoms, also known as ethyleneimines, within the molecule. Examples include diphenylmethane-4,4'-bis(1-aziridinecarboxamide), toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, isophthaloylbis-1-(2-methylaziridine), tris-1-aziridinylphosphine oxide, hexamethylene-1,6-bis(1-aziridinecarboxamide), trimethylolpropane tris-β-aziridinylpropionate, and tetramethylolmethane tris-β-aziridinylpropionate.

[0053] Of these crosslinking agents, isocyanate compounds, particularly an adduct obtained by reacting tolylene diisocyanate with a polyol, a dimer of tolylene diisocyanate, a trimer of tolylene diisocyanate, an adduct obtained by reacting hexamethylene diisocyanate with a polyol, a dimer of hexamethylene diisocyanate, a trimer of hexamethylene diisocyanate, an adduct obtained by reacting xylene diisocyanate with a polyol, an adduct obtained by reacting hydrogenated xylylene diisocyanate with a polyol, isophorone diisocyanate and / or an adduct obtained by reacting isophorone diisocyanate with a polyol, and mixtures of these isocyanate compounds are preferably used.

[0054] The content of the crosslinking agent in the adhesive is usually about 0.01 to 5 parts by mass, preferably 0.03 to 2 parts by mass, and more preferably 0.1 to 1.5 parts by mass, per 100 parts by mass of the resin contained in the adhesive.

[0055] (Silane compounds) The adhesive constituting the adhesive-attached resin film of the present invention preferably contains a silane-based compound from the viewpoint of improving adhesion to a glass substrate when the adhesive-attached resin film or the adhesive-attached polarizing plate is laminated to a glass substrate after formation of the film. In particular, it is preferable to incorporate the silane-based compound into the resin before blending with the crosslinking agent.

[0056] Examples of silane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, and 3-glycidoxypropylethoxydimethylsilane. Two or more silane compounds may be used.

[0057] The silane-based compound may be a silicone oligomer type. When the silicone oligomer is expressed in the form of a (monomer)-(monomer) copolymer, for example, the following can be mentioned:

[0058] mercaptopropyl group-containing copolymers such as 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer;

[0059] mercaptomethyl group-containing copolymers such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer;

[0060] methacryloyloxypropyl group-containing copolymers such as 3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer;

[0061] acryloyloxypropyl group-containing copolymers such as 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer;

[0062] vinyl group-containing copolymers such as vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer;

[0063] These silane compounds are often liquids. The content of the silane compound in the adhesive is usually about 0.01 to 10 parts by mass, preferably 0.03 to 2 parts by mass, and more preferably 0.03 to 1 part by mass, per 100 parts by mass of the resin contained in the adhesive.

[0064] <Resin film> In a resin film with a pressure-sensitive adhesive, the pressure-sensitive adhesive layer and the resin film are in direct contact with each other, that is, the pressure-sensitive adhesive layer and the resin film are laminated together.

[0065] The resin film constituting the pressure-sensitive adhesive resin film of the present invention is not particularly limited, but examples thereof include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; fluorinated polyolefin resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyethylene fluoride; polyester resins such as polyethylene naphthate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymers; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose resins such as triacetyl cellulose, diacetyl cellulose, and cellophane; (meth)acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; and other resin films composed of polystyrene, polycarbonate, polyarylate, polyimide, etc.

[0066] In the present invention, the resin film may contain various additives. Examples of additives include ultraviolet absorbers, antioxidants, surfactants, plasticizers, lubricants, and antiblocking agents. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, triazine compounds, cyanoacrylate compounds, and nickel complex salt compounds. The resin film can be produced by film formation and stretching using a known method.

[0067] In the present invention, the thickness of the resin film is preferably 10 μm or more, more preferably 12 μm or more, even more preferably 15 μm or more, and preferably 200 μm or less, more preferably 180 μm or less, and even more preferably 150 μm or less. When the thickness of the resin film is above the above-mentioned lower limit, the total amount of ionic compound absorbed or adsorbed into the substrate increases, thereby enhancing the effect of selecting the ionic compound of the present invention, such as a pyridinium salt. When the thickness of the resin film is below the above-mentioned upper limit, when a polarizer is combined with the surface of the resin film opposite to the surface in contact with the pressure-sensitive adhesive layer, the total amount of ionic compound that migrates to the resin film and reaches the polarizer via the resin film increases, making it more likely that the polarizer will be deteriorated by the ionic compound, thereby enhancing the effect of suppressing the migration of ionic compounds according to the present invention.

[0068] In the present invention, a resin film is immersed in a 50% by weight aqueous potassium iodide solution for 4.5 hours in an air atmosphere at 23°C and 55% RH, rinsed with water for 15 seconds, and dried in a dark place at 23°C and 55% RH for 15 hours. After this treatment, the maximum change D in the absorbance of light at a wavelength of 355 to 365 nm compared to before the treatment is 5% or more, preferably 8% or more. When the maximum change D is equal to or greater than the lower limit, the resin film has high ion permeability, allowing various ionic compounds to easily pass through. However, the ion permeability of the ionic compounds of the present invention, particularly pyridinium salts, is very low, allowing the antistatic function to be maintained and minimizing adverse effects on the optical performance (e.g., polarization performance) of the optical film. The maximum change D is defined by Equation (3) below and is typically 50% or less, e.g., 25% or less. D can also be calculated from absorbance.

[0069] Such a resin film has a high ability to allow potassium iodide, a common ionic compound, to penetrate into the substrate, and similarly, the ionic compound of the present invention, such as a pyridinium salt, also easily penetrates into the substrate.

[0070] Examples of resin films with high ion permeability defined by the above method include "ZRD40" and "ZRE34" manufactured by Fujifilm Corporation. Examples of resin films with low ion permeability include "Fujitac TD," "Z-TAC," and "KC4ZDW" manufactured by Fujifilm Corporation, and "Konica Minolta TAC Film KC" and "Zero Tac" manufactured by Konica Minolta Opto, Inc.

[0071] Examples of resin films that are the subject of the present invention include optical films including polarizing films, protective films, and / or retardation films, and surface protection films that are attached to the surface of the optical film opposite the pressure-sensitive adhesive layer and protect the surface until use. When the resin film is a surface protection film, the pressure-sensitive adhesive resin film of the present invention can be attached to the surface of an optical film to form a surface protection film that protects the surface until use. In this case, it exhibits excellent antistatic properties, and can reduce static electricity generated when, for example, the optical film is attached to a liquid crystal cell via the pressure-sensitive adhesive layer on the opposite side of the surface protection film, and then the surface protection film is peeled off.

[0072] <Preparation of adhesive and formation of adhesive layer> The above-mentioned components constituting the pressure-sensitive adhesive are mixed in a solvent, and after forming a solution, the solution is applied to a suitable substrate and dried to form a pressure-sensitive adhesive layer sheet.The substrate used here is generally a plastic film, and a typical example thereof can be a release film that has been subjected to a release treatment.The release film can be, for example, a film made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyarylate, etc., on the surface on which the pressure-sensitive adhesive layer sheet is formed, which has been subjected to a release treatment such as silicone treatment.In addition, the pressure-sensitive adhesive layer can also be formed by directly applying the pressure-sensitive adhesive to a resin film and drying it.

[0073] <Adhesive-backed resin film and adhesive-backed polarizing plate> The pressure-sensitive adhesive resin film of the present invention comprises a pressure-sensitive adhesive layer sheet composed of the above-described pressure-sensitive adhesive provided on at least one side of a resin film. In this way, a pressure-sensitive adhesive resin film is formed in which the pressure-sensitive adhesive layer sheet is bonded to the resin film. The pressure-sensitive adhesive resin film of the present invention comprises a resin film and a pressure-sensitive adhesive layer provided on at least one side of the resin film. Furthermore, when the resin film used as the adherend is laminated with a polarizing film, a pressure-sensitive adhesive polarizing plate is formed. The pressure-sensitive adhesive layer sheet may also be simply referred to as the "pressure-sensitive adhesive layer" in this specification.

[0074] The polarizing film used in the adhesive polarizing plate refers to a film in which a transparent protective film (transparent resin film) is laminated on one or both sides of a polarizer. Specific examples of polarizing films include a uniaxially stretched polyvinyl alcohol resin film in which dichroic pigments such as iodine and dichroic dyes are adsorbed and aligned. The thickness of the polarizing film is not particularly limited, but a film having a thickness of 0.5 to 35 μm is usually used. In addition, the resin film used here may be a zero-phase difference film or a phase difference film. The zero-phase difference film is a film having a front retardation R e and retardation R th The retardation film is an optically isotropic film with a small front retardation R e and retardation R th At least one of the retardation values ​​is −15 to 15 nm.

[0075] In addition, the front retardation R e and retardation R in the thickness direction th is defined by the following equations (1) and (2). R th = (n x +n y ) / 2-n z 〕×d (1) R e =(n x -n y)×d (2)

[0076] In the formula, n x is the refractive index in the slow axis direction (x-axis direction) in the film plane, and n y is the refractive index in the fast axis direction in the film plane (the y-axis direction perpendicular to the x-axis in the plane), and n z is the refractive index in the thickness direction of the film (z-axis direction perpendicular to the film surface), and d is the thickness of the film.

[0077] Here, the retardation value can be a value at any wavelength within the range of about 500 to 650 nm, which is near the center of the visible light spectrum, but in this specification, the retardation value at a wavelength of 590 nm is used as the standard. th and in-plane retardation R e can be measured using various commercially available retardation meters.

[0078] In the present invention, the adhesive can also be applied directly onto a polarizing plate which is a laminate of a polarizing film and a resin film, and then dried to provide a polarizing plate with the adhesive.

[0079] Furthermore, in another embodiment of the present invention, there is also provided a pressure-sensitive adhesive resin film having the above-mentioned resin film and the above-mentioned pressure-sensitive adhesive layer provided on at least one side of the resin film, wherein the pressure-sensitive adhesive layer is composed of the above-mentioned resin and a pressure-sensitive adhesive containing an ionic compound that is a pyridinium salt represented by the above-mentioned formula (1), and wherein the resin film is immersed in a 50% by mass aqueous potassium iodide solution for 4.5 hours in an atmospheric atmosphere of 23°C and 55% RH, washed with water for 15 seconds, and dried in a dark place for 15 hours, after which the maximum change in the amount of light absorbed at a wavelength of 355 to 365 nm compared to before the treatment is 5% or more.

[0080] <Optical laminate> In the present invention, an optical laminate (hereinafter also referred to as "the optical laminate of the present invention") can be formed by laminating the adhesive layer side of the above-mentioned adhesive-attached resin film or adhesive-attached polarizing plate on a glass substrate. That is, the optical laminate of the present invention comprises the above-mentioned adhesive-attached resin film and a glass substrate laminated on the adhesive layer side. To form an optical laminate by laminating an adhesive-attached resin film or adhesive-attached polarizing plate on a glass substrate, for example, the release film may be peeled off from the adhesive-attached resin film obtained as described above, and the exposed adhesive layer surface may be attached to the surface of the glass substrate. Examples of glass substrates include glass substrates for liquid crystal cells, anti-glare glass, and glass for sunglasses. Among these, an optical laminate formed by laminating an adhesive-attached polarizing plate (upper polarizing plate) on a glass substrate on the front side (viewing side) of a liquid crystal cell and another adhesive-attached polarizing plate (lower polarizing plate) on a glass substrate on the back side of the liquid crystal cell is preferred because it can be used as a panel for a liquid crystal display device (liquid crystal panel). Examples of materials for the glass substrate include soda lime glass, low alkali glass, and non-alkali glass, but non-alkali glass is preferably used for the liquid crystal cell.

[0081] In the optical laminate of the present invention, the pressure-sensitive adhesive layer absorbs and relieves stress caused by dimensional changes in the optical film and glass substrate under humid and hot conditions, thereby reducing local stress concentration and suppressing lifting and peeling of the pressure-sensitive adhesive layer from the glass substrate. Furthermore, optical defects caused by uneven stress distribution are prevented, thereby suppressing whiteout. Furthermore, when the pressure-sensitive adhesive-attached resin film of the present invention is once laminated onto a glass substrate and then peeled again to resolve a defect, even if the resin film is peeled from the glass substrate together with the pressure-sensitive adhesive, there is little adhesive residue or cloudiness on the surface of the glass substrate after peeling, and the glass substrate can be reused, resulting in excellent reworkability.

[0082] Some examples of suitable layer structures for the optical laminate of the present invention are shown in cross-sectional schematic diagrams in Figures 1 to 4. In the example shown in Figure 1, a pressure-sensitive adhesive layer 20 is formed on one surface of a resin film 3 to form a pressure-sensitive adhesive-attached resin film 5. The surface of the pressure-sensitive adhesive layer 20 opposite to the resin film 3 is then attached to a liquid crystal cell 30, which is a glass substrate, to form an optical laminate 40.

[0083] 2, a polarizing plate 10 is constructed by attaching a first resin film 4 having a surface treatment layer 2 to one surface of a polarizer 1 on the side opposite the surface treatment layer 2, and attaching a second resin film 3 to the other surface of the polarizer 1. A pressure-sensitive adhesive layer 20 is provided on the outer side of the second resin film 3 constituting the polarizing plate 10, thereby constructing a pressure-sensitive adhesive-coated polarizing plate 15. The surface of the pressure-sensitive adhesive layer 20 opposite the polarizing plate 10 is then attached to a liquid crystal cell 30, which is a glass substrate, to construct an optical laminate 40.

[0084] 3, a resin film 4 having a surface treatment layer 2 is attached to one surface of a polarizer 1 on the side opposite the surface treatment layer 2, and a resin film 7 is attached to the side of the polarizer 1 opposite the resin film 4 via an interlayer adhesive 6, thereby forming a polarizing plate 10. An adhesive layer 20 is provided on the outer side of the resin film 7 constituting the polarizing plate 10, thereby forming an adhesive-coated polarizing plate 15. The surface of the adhesive layer 20 opposite the resin film 7 is then attached to a liquid crystal cell 30, which is a glass substrate, to form an optical laminate 40.

[0085] 4, a first resin film 4 having a surface treatment layer 2 is attached to one surface of a polarizer 1 on the side opposite to the surface treatment layer 2, a second resin film 3 is attached to the other surface of the polarizer 1, and a resin film 7 is attached to the outer side of the second resin film 3 via an interlayer adhesive 6, thereby forming a polarizing plate 10. An adhesive layer 20 is provided on the outer side of the resin film 7 constituting the polarizing plate 10, thereby forming an adhesive-coated polarizing plate 15. The surface of the adhesive layer 20 opposite to the resin film 7 is then attached to a liquid crystal cell 30, which is a glass substrate, to form an optical laminate 40.

[0086] In these examples, the first resin film 4 and the second resin film 3 are generally made of triacetyl cellulose films, but may also be made of the various transparent resin films described above. The surface treatment layer formed on the surface of the first resin film 4 may be a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, etc. It is also possible to provide a plurality of these layers.

[0087] When a resin film 7 is laminated in a polarizing plate 10 as in the examples shown in FIGS. 3 and 4 , a suitable example of the resin film 7 is a quarter-wave plate for small- to medium-sized liquid crystal display devices. In this case, the polarizer 1 and the resin film 7, which is a quarter-wave plate, are typically arranged so that their absorption axes intersect at approximately 45 degrees. However, this angle may be slightly shifted from 45 degrees depending on the characteristics of the liquid crystal cell 30. On the other hand, in large liquid crystal display devices such as televisions, retardation films having various retardation values ​​tailored to the characteristics of the liquid crystal cell 30 are used to compensate for the retardation and viewing angle of the liquid crystal cell 30. In this case, the resin film 7 is typically arranged so that its absorption axis is approximately perpendicular or parallel to the absorption axis of the polarizer 1. When the resin film 7 is configured as a quarter-wave plate, a uniaxially or biaxially stretched film is preferably used. Furthermore, when the resin film 7 is provided for the purpose of phase difference compensation or viewing angle compensation of the liquid crystal cell 30, in addition to a uniaxially or biaxially stretched film, what is called an optical compensation film, such as a film that is oriented in the thickness direction in addition to being uniaxially or biaxially stretched, or a film in which a phase difference-producing substance such as a liquid crystal is applied to a support film and the orientation is fixed, can also be used as the resin film 7.

[0088] Similarly, as in the examples shown in FIGS. 3 and 4 , when a resin film 7 is bonded to a polarizing plate 10 via an interlayer adhesive 6, a general acrylic adhesive is typically used as the interlayer adhesive 6. However, it is also possible to use the adhesive layer sheet defined in the present invention. When the absorption axis of the polarizer 1 and the slow axis of the resin film 7 are arranged to be substantially perpendicular or parallel, as in the large-size liquid crystal display device described above, roll-to-roll bonding can be used to bond the polarizer 1 and the resin film 7 via the interlayer adhesive 6 during the production of the polarizing plate 10. Furthermore, in applications where re-peelability between the polarizer 1 and the resin film 7 is not required, an adhesive that firmly bonds the two and becomes inseparable once bonded can be used instead of the interlayer adhesive 6 shown in FIGS. 3 and 4 . Examples of such adhesives include water-based adhesives composed of an aqueous solution or aqueous dispersion that exhibit adhesive strength upon evaporation of the solvent water, and ultraviolet-curable adhesives that harden and exhibit adhesive strength upon exposure to ultraviolet light.

[0089] 3 and 4, the resin film 7 having the adhesive layer 20 formed thereon can be distributed by itself and can be the adhesive-attached resin film of the present invention. The adhesive-attached resin film having the adhesive layer formed on the retardation film can be made into an optical laminate by laminating the adhesive layer to a liquid crystal cell, which is a glass substrate, and can also be made into another adhesive-attached resin film by laminating a polarizing plate to the retardation film side.

[0090] 1 to 4 show examples in which a pressure-sensitive adhesive resin film 5 or a pressure-sensitive adhesive polarizing plate 15 is disposed on the viewing side of a liquid crystal cell 30, but the pressure-sensitive adhesive resin film of the present invention can also be disposed on the rear side of the liquid crystal cell, i.e., on the backlight side. When the pressure-sensitive adhesive resin film of the present invention is disposed on the rear side of the liquid crystal cell, a resin film without a surface treatment layer can be used instead of the resin film 4 having the surface treatment layer 2 shown in FIGS. 1 to 4, and the rest of the configuration can be the same as in FIGS. 1 to 4, and the film can be attached to the liquid crystal cell 30 via a pressure-sensitive adhesive layer 20. In this case, it is also possible to provide various optical films known to be disposed on the rear side of liquid crystal cells, such as a brightness enhancement film, a light-collecting film, or a diffusion film, on the outer side of the resin film constituting the polarizing plate.

[0091] As explained above, the pressure-sensitive adhesive resin film and optical laminate of the present invention can be suitably used in organic EL displays and liquid crystal displays. Liquid crystal displays formed from the pressure-sensitive adhesive resin film and optical laminate of the present invention can be used, for example, in liquid crystal displays for personal computers including notebook-type, desktop-type, and PDAs (Personal Digital Assistants), televisions, in-vehicle displays, electronic dictionaries, digital cameras, digital video cameras, electronic desk calculators, clocks, etc. [Example]

[0092] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, parts and % representing amounts used or contents are by mass unless otherwise specified.

[0093] In the following examples, the weight-average molecular weight is a value measured in terms of standard polystyrene using a GPC apparatus equipped with five columns connected in series, four columns of "TSKgel XL" manufactured by Tosoh Corporation and one column of "Shodex GPC KF-802" manufactured by Showa Denko K.K., and tetrahydrofuran as the eluent, under the conditions of a sample concentration of 5 mg / mL, a sample introduction amount of 100 μL, a temperature of 40°C, and a flow rate of 1 mL / min.

[0094] "Solubility" refers to the solubility (g) of an ionic compound in 100 g of water at 60°C. The solubility was determined according to the following procedure. First, 300 mg of a precisely weighed ionic compound was mixed with 2 mL of pure water and then stored at 60°C for 24 hours with stirring. If the obtained ionic compound contained a solvent, the solvent was removed by vacuum distillation to obtain the dried ionic compound, which was then precisely weighed. Next, a portion (precisely weighed) of the aqueous layer was sampled and appropriately diluted with acetonitrile. The mass concentration of the ionic compound dissolved in the obtained measurement sample was quantified using the absolute calibration curve method of liquid chromatography-mass spectrometry (LC / MS). The LC / MS measurement conditions were as follows. The solubility of the ionic compound was determined based on the quantitative results. Each quantitative determination was performed twice, and the average value was used as the solubility of the ionic compound.

[0095] Analyzer: Agilent Technologies LC / MS instrument 1260 type / 6130 type Separation column: Kinetex 2.6u C18 100A (3.0 x 100mm, 2.7μm) Mobile phase: Gradient method using a mixed solvent of water / acetonitrile with 0.05% TFA Mobile phase flow rate: 0.5 mL / min. Sample injection volume: 2.5 μL Oven temperature: 40℃ UV detection wavelength: 254 nm MS detection conditions: Electrospray ionization (ESI) method Positive

[0096] [Preparation of adhesive] A pressure-sensitive adhesive was prepared using the following components, each of which will be described below.

[0097] <Acrylic resin> [Polymerization Example 1] A reaction vessel equipped with a condenser, nitrogen inlet, thermometer, and stirrer was charged with a mixture of 81.8 parts ethyl acetate as solvent, 69.4 parts butyl acrylate, 20.0 parts methyl acrylate, 8.0 parts 2-(2-phenoxyethoxy)ethyl acrylate, 1.0 parts 2-hydroxyethyl acrylate, and 0.6 parts acrylic acid. The air in the vessel was purged with nitrogen gas to remove oxygen, while the internal temperature was raised to 55°C. Then, a solution of 0.15 parts azobisisobutyronitrile (polymerization initiator) in 10 parts ethyl acetate was added in its entirety. One hour after the initiator addition, ethyl acetate was continuously added to the reaction vessel at a rate of 17.3 parts / hr to achieve a 30% acrylic resin concentration. The internal temperature was maintained at 54-56°C for 12 hours. Finally, ethyl acetate was added to the reaction vessel to adjust the concentration of the acrylic resin to 20%. The resulting acrylic resin had a weight average molecular weight (Mw) of 1.35 million, calculated as polystyrene by GPC, and an Mw / Mn ratio of 5.5. This acrylic resin will be referred to as "acrylic resin A" below.

[0098] <Ionic compounds> Ionic compound 1: N-benzylpyridinium bis(trifluoromethanesulfonyl)imide (powder at 30°C)

[0099] [ka]

[0100] Ionic compound 2: N-decylpyridinium bis(trifluoromethanesulfonyl)imide (powder at 30°C)

[0101] [ka]

[0102] Ionic compound 3: N-nonyl-4-methylpyridinium hexafluorophosphate (powder at 30°C)

[0103] [ka]

[0104] Ionic compound 4: N-methylpyridinium bis(trifluoromethanesulfonyl)imide (powder at 30°C)

[0105] [ka]

[0106] Ionic compound 5: N-propylpyridinium bis(trifluoromethanesulfonyl)imide (liquid at 25°C)

[0107] [ka]

[0108] <Crosslinking agent> Coronate L: Ethyl acetate solution of trimethylolpropane adduct of tolylene diisocyanate (resin concentration 75%), manufactured by Tosoh Corporation.

[0109] <Silane compounds> KBM-403: Glycidoxypropyltrimethoxysilane (liquid), manufactured by Shin-Etsu Chemical Co., Ltd.

[0110] 100 parts of acrylic resin A produced in Polymerization Example 1 was mixed with 0.5 parts of the above crosslinking agent and 1.5 parts of a silane-based compound, and then the ionic compounds shown in Table 1 were mixed in the amounts shown in Table 1, and ethyl acetate was added so that the resin concentration became 14%, to obtain each adhesive.

[0111] [Table 1]

[0112] [Examples 1 and 2 and Comparative Examples 1, 2, 4 and 5] Each of the pressure-sensitive adhesives listed in Table 1 was applied to the release-treated surface of a release-treated polyethylene terephthalate film (trade name "PET 3811," manufactured by Lintec Corporation; referred to as "separator") using an applicator to a dry thickness of 20 μm, and then dried at 100°C for 1 minute to form a sheet-like pressure-sensitive adhesive layer. Next, a three-layer polarizing plate (P1) was formed by laminating an 80 μm-thick acrylic resin film (trade name "Technoloy S001," manufactured by Sumitomo Chemical Co., Ltd.) containing a UV absorber to one side of an iodine-adsorbed and oriented polyvinyl alcohol polarizing film and a 32 μm-thick triacetyl cellulose-based transparent resin film (trade name "ZRE34," manufactured by Fujifilm Corporation) as a transparent resin film to the other side. The side of the sheet-like pressure-sensitive adhesive layer obtained above (the pressure-sensitive adhesive layer side) opposite the separator was then laminated to the triacetyl cellulose film side using a laminator to obtain a pressure-sensitive adhesive polarizing plate.

[0113] [Example 3 and Comparative Example 3] An adhesive-backed polarizing plate was obtained in the same manner as in Example 1, except that the adhesives listed in Table 1 were used instead of the above adhesives, and a three-layer polarizing plate (P2) was used instead of the polarizing plate (P1), in which an 80 μm thick film made of acrylic resin containing an ultraviolet absorber [product name "Technoloy S001", manufactured by Sumitomo Chemical Co., Ltd.] was attached to one side of an iodine-adsorbed and oriented polyvinyl alcohol polarizing film, and a 42 μm thick triacetyl cellulose-based transparent resin film (manufactured by Fujifilm Corporation, product name "ZRD40") was attached as a transparent resin film to the other side.

[0114] [Reference Examples 1 and 2] An adhesive-backed polarizing plate was obtained in the same manner as in Example 1, except that the adhesives listed in Table 1 were used instead of the above adhesives, and a three-layer polarizing plate (P3) was used in place of the polarizing plate (P1), in which an 80 μm thick film made of acrylic resin containing an ultraviolet absorber [product name "Technoloy S001", manufactured by Sumitomo Chemical Co., Ltd.] was attached to one side of an iodine-adsorbed and oriented polyvinyl alcohol polarizing film, and a 41 μm thick triacetyl cellulose-based transparent resin film (manufactured by Konica Minolta, Inc., product name "KC4CR") was attached to the other side as a transparent resin film.

[0115] [Reference example 3] An adhesive-backed polarizing plate was obtained in the same manner as in Example 1, except that the adhesives listed in Table 1 were used instead of the above adhesives, and a three-layer polarizing plate (P4) was used in place of the polarizing plate (P1), in which an 80 μm thick film made of acrylic resin containing an ultraviolet absorber [product name "Technoloy S001", manufactured by Sumitomo Chemical Co., Ltd.] was attached to one side of an iodine-adsorbed and oriented polyvinyl alcohol polarizing film, and a 53 μm thick cycloolefin-based transparent resin film (manufactured by Zeon Corporation, product name "ZEONOR") was attached to the other side as a transparent resin film.

[0116] [Evaluation of ion permeability of transparent resin film] The ion permeability of each transparent resin film, which was an adherend of the adhesive used in producing the above polarizing plate with adhesive, was evaluated by the following procedure.

[0117] The transparent resin film was cut into a 4 cm x 4 cm square and the transmittance was measured using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-2450). The minimum value of the transmittance at wavelengths of 355 to 365 nm was designated as A0 [%]. After the measurement, the transparent resin film piece was immersed in a 50 mass % potassium iodide aqueous solution in an atmospheric atmosphere at 23°C and 55% RH for 4.5 hours, then removed, washed with running water for 15 seconds, and air-dried in a dark room for 15 hours, and then measured using the ultraviolet-visible spectrophotometer. The minimum value of the transmittance at wavelengths of 355 to 365 nm was designated as A0 [%]. 4.5 [%].

[0118] As an index showing the ion permeability of the transparent resin film, the maximum change (D) in the amount of absorbance before and after immersion of the film in an aqueous potassium iodide solution was defined as shown in the following formula (3). Maximum change in absorbance D [%] = A0 - A 4.5 (3) The ZRE34 used in this study had a D of 22%, and the ZRD40 had a D of 15%, while the KC4CR and ZEONOR had D < 5%.

[0119] [Evaluation of antistatic properties of adhesive-backed polarizing plates] The separators of the polarizing plates with adhesive obtained in each Example, Comparative Example, and Reference Example were peeled off, and the surface resistance value of the adhesive was measured using a surface resistivity measuring device ("Hirest-up MCP-HT450" (trade name) manufactured by Mitsubishi Chemical Corporation) to evaluate the antistatic properties. The evaluation was carried out after preparing the polarizing plate with adhesive and after curing it for 1 day and 14 days under the conditions of a temperature of 23°C and a relative humidity of 65%. In order to maintain good antistatic properties for a long period of time, the surface resistance value after curing (Rs1) for 1 day and the surface resistance value after curing (Rs 14 Specifically, as an index of the long-term stability of antistatic properties, the ratio of the surface resistance value after 1 day of aging to the surface resistance value after 14 days of aging was defined as the rate of change in surface resistance (E) by the following formula (4): Surface resistance change rate E [%] = Rs 14 / Rs1×100 (4) The results are summarized in Table 2.

[0120] [Table 2]

[0121] [Preparation of optical laminate and heat resistance durability test] After peeling the separator from the prepared polarizing plate with adhesive, the adhesive layer side was attached to one side of a glass substrate for liquid crystal cells ("Eagle XG" (trade name) manufactured by Corning Incorporated) to prepare an optical laminate. A heat resistance durability test was performed on this optical laminate, in which it was stored for 500 hours under dry conditions at a temperature of 80°C, and the optical laminate after the test was visually observed. After the test, the degree of lifting and peeling of the optical laminate from the glass substrate, i.e., the distance from the edge of the optical laminate to the position where peeling of the optical laminate occurred, was measured using a magnifying glass.

[0122] As a result, no changes in appearance such as lifting, peeling, or bubbling were observed in the optical laminates produced using the polarizing plates with pressure-sensitive adhesive obtained in Examples 1 to 3, Comparative Examples 1 to 5, and Reference Examples 1 and 2. On the other hand, in Reference Example 3, changes in appearance such as lifting, peeling, and bubbling were somewhat noticeable.

[0123] As is clear from the above, Examples 1 and 2, which use adhesives containing the ionic compounds specified in the present invention (ionic compounds 1 and 2), have smaller E values ​​when a triacetyl cellulose substrate with a D of 5% or more and high ion permeability is used as the adherend, compared to Comparative Examples 1, 2, 4 and 5, which contain ionic compounds 3 to 5 whose solubility in water at 60°C is outside the range specified in the present invention, and are therefore able to exhibit stable antistatic properties over a long period of time.

[0124] Furthermore, a comparison between Example 3 and Comparative Example 3 confirmed that even in the case of ZRD40, where D is smaller than ZRE34, it is possible to keep the E value low when using an adhesive containing the ionic compound defined in the present invention, and that antistatic properties can be maintained for a long period of time even when a resin film with even higher ion permeability is used as the adherend. [Industrial Applicability]

[0125] The pressure-sensitive adhesive resin film of the present invention provides stable antistatic properties for a long period of time even when a resin film with high ion permeability is used as the adherend. Furthermore, it has excellent durability even when attached to glass via the pressure-sensitive adhesive layer. This pressure-sensitive adhesive resin film and pressure-sensitive adhesive polarizing plate are suitable for use in liquid crystal displays by being attached to a glass substrate. [Explanation of symbols]

[0126] 1 polarizer 2. Surface treatment layer 3 (Second) Resin Film 4. First Resin Film 5. Adhesive resin film 6 Interlayer adhesive 7 Resin film 10 Polarizing plate 15 Polarizing plate with adhesive 20 adhesive layer 30 Liquid crystal cell (glass substrate) 40 Optical laminate

Claims

1. A resin film with a pressure-sensitive adhesive, comprising a resin film and a pressure-sensitive adhesive layer provided on at least one side of the resin film, the pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive containing a (meth)acrylic resin, an ionic compound having a solubility in water at 60°C of 0.4 g / 100 g or less, a crosslinking agent, and a silane-based compound; the ionic compound is a pyridinium salt, The resin film is immersed in a 50% by mass aqueous solution of potassium iodide for 4.5 hours in an atmospheric air atmosphere of 23°C and 55% RH, washed with water for 15 seconds, and then dried in a dark place for 15 hours, after which the maximum change in the amount of absorbance of light at a wavelength of 355 to 365 nm compared to before the treatment is 5% or more.

2. 2. The adhesive-attached resin film according to claim 1, wherein the adhesive contains 0.05 to 8 parts by mass of the ionic compound per 100 parts by mass of the resin.

3. 3. The pressure-sensitive adhesive resin film according to claim 1, wherein the resin film has a thickness of 10 to 200 μm.

4. An optical laminate comprising the pressure-sensitive adhesive resin film according to any one of claims 1 to 3 and a glass substrate laminated on the pressure-sensitive adhesive layer side.

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