JP7808935B2 - Polarizing film with separator and adhesive layer - Google Patents

Description

The present invention relates to a polarizing film with a separator and an adhesive layer.

Polarizing films are used in image display devices such as liquid crystal display devices. Adhesives are typically used to attach polarizing films to display panels such as liquid crystal panels. Generally, adhesive-coated polarizing films are used, in which an adhesive is pre-applied as an adhesive layer on one side of the polarizing film, due to advantages such as the fact that no drying process is required to attach the polarizing film. Furthermore, adhesive-coated polarizing films typically have a separator (also known as a release film or release liner) on the surface of the adhesive layer to protect the adhesive layer before application.

In recent years, polarized films with adhesive layers have become thinner and less stiff, which has led to the problem of the separator being difficult to peel from the adhesive layer. This has led to a demand for separators with easier peeling. Meanwhile, the adhesive layer is required to have functionality such as conductivity and reworkability, and efforts are underway to develop polarized films with separators and adhesive layers that combine easy-to-peel separators with the functionality of the adhesive layer.

For example, Patent Document 1 describes a polyester film for substrate-less double-sided PSA sheets that can minimize peel speed dependency, has good releasability, and low migration, and
A polyester film has been proposed that is characterized by having a reactive silicone resin having alkenyl groups and alkyl groups as functional groups, an unreactive silicone resin having a mass average molecular weight of 400,000 or more, and a silicone-based release layer containing a platinum-based catalyst.

Furthermore, Patent Document 2 discloses a release sheet that exhibits a very small release force and can be used as an ultra-light release sheet,
The film comprises a substrate and a release agent layer provided on at least one surface of the substrate,
the substrate is made of a plastic film,
the release agent layer is formed from a release agent composition containing a polyorganosiloxane having a weight average molecular weight of 5,000 or more and 100,000 or less,
A release sheet has been proposed in which the thickness of the release agent layer is 0.3 μm or more and 1.0 μm or less.

JP 2015-208863 A JP 2017-149048 A

However, even when a separator having a silicone-based release layer as described in Patent Document 1 or a release agent layer as described in Patent Document 2 is used, the problem of difficulty in peeling the separator from the adhesive layer of a thinned polarized film with an adhesive layer could not be solved.

The objective of the present invention is to provide a polarized film with a separator and adhesive layer that has conductive properties, while also achieving easy peelability of the separator and reworkability of the adhesive layer.

As a result of extensive research into resolving the above-mentioned problems, the inventors discovered that the above problems could be solved by using a polarizing film with an adhesive layer having the following separator, leading to the completion of the present invention.

The present invention provides a separator-attached pressure-sensitive adhesive layer polarizing film, in which a separator-attached pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer on a separator is provided on one or both sides of a polarizing film,
the separator has a release layer on a substrate film,
the release layer contains a reactive silicone resin having a reactive functional group and a non-reactive silicone resin having a weight average molecular weight of 400,000 or more;
the content of the reactive silicone resin is 50 to 70 mass% and the content of the non-reactive silicone resin is 30 to 50 mass% relative to 100 mass% of the total content of the reactive silicone resin and the non-reactive silicone resin;
The release layer has an elastic modulus of less than 1.5 MPa,
the pressure-sensitive adhesive layer is provided on the release layer,
the pressure-sensitive adhesive layer contains a conductive agent,
The present invention relates to a polarizing film with a pressure-sensitive adhesive layer having a separator, wherein the pressure-sensitive adhesive layer contains a base polymer containing less than 0.5% by mass of a carboxy group-containing monomer as a monomer unit.

The conductive agent is preferably an alkali metal salt and/or an organic cation-anion salt.

The pressure-sensitive adhesive layer preferably has a surface resistance of 1.0×10 ¹² Ω/□ or less.

Furthermore, it is preferable that the peel force when peeling the separator from the pressure-sensitive adhesive layer be 0.09 N/50 mm or less.

It is also preferable that the adhesive strength of the adhesive layer is 8 N/25 mm or less.

Furthermore, it is preferable that the thickness of the polarizing film be 75 μm or less.

The separator of the present invention contains a specific ratio of a reactive silicone resin having reactive functional groups and a non-reactive silicone resin having a weight-average molecular weight of 400,000 or more, and has a release layer with an elastic modulus of less than 1.5 MPa. Therefore, even in a thin polarized film with a pressure-sensitive adhesive layer, the separator can be easily peeled from the pressure-sensitive adhesive layer. Furthermore, the pressure-sensitive adhesive layer of the present invention contains a conductive agent that segregates on the release layer side of the pressure-sensitive adhesive layer, making it extremely easy to peel the separator from the pressure-sensitive adhesive layer. Furthermore, the pressure-sensitive adhesive layer of the present invention contains a base polymer containing less than 0.5% by mass of a carboxyl group-containing monomer as a monomer unit, resulting in low adhesive strength and excellent reworkability. By using the separator and pressure-sensitive adhesive layer in combination, a polarized film with a separator and a pressure-sensitive adhesive layer can be obtained that has conductive properties and combines the easy peelability of the separator with the reworkability of the pressure-sensitive adhesive layer.

The polarizing film with a separator and an adhesive layer of the present invention has a separator-attached adhesive layer, which has an adhesive layer on a separator, provided on one or both sides of the polarizing film. Each component will be described in detail below.

<Separator-attached adhesive layer>
The separator-attached pressure-sensitive adhesive layer of the present invention has a pressure-sensitive adhesive layer on a separator, and the separator has a release layer on a substrate film. The pressure-sensitive adhesive layer is provided on the release layer. The separator may also have an oligomer blocking layer between the substrate film and the release layer.

<Base film>
The substrate film can be a plastic film. Examples of the plastic film include polyolefin films such as polyethylene film, polypropylene film, polybutene film, polybutadiene film, and polymethylpentene film; vinyl chloride films such as polyvinyl chloride film and vinyl chloride copolymer film; polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polynaphthylene terephthalate film; and polyurethane films and ethylene-vinyl acetate copolymer films. Of the plastic films, polyester films are preferably used.

The thickness of the substrate film is typically 5 to 200 μm, preferably 5 to 100 μm, and more preferably 10 to 50 μm. The substrate film may be subjected to a surface treatment such as corona treatment or plasma treatment.

<Release layer>
The release layer is provided to improve releasability from the pressure-sensitive adhesive layer. The release layer is formed from a silicone-based release agent, which contains a reactive silicone resin having a reactive functional group and a non-reactive silicone resin having a weight-average molecular weight of 400,000 or more. By using a reactive silicone resin having a reactive functional group, a crosslinked structure via the reactive functional group can be formed in the release layer by heating or active energy ray irradiation, making it easier to adjust the elastic modulus of the release layer to the desired range. Furthermore, by using a non-reactive silicone resin having a weight-average molecular weight of 400,000 or more, easy releasability can be imparted. The release layer can be formed as a coating layer on a substrate film or an oligomer blocking layer. The release layer can also be formed by transfer.

Examples of reactive silicone resins having reactive functional groups include polyorganosiloxanes having reactive functional groups. Examples of polyorganosiloxanes include polydimethylsiloxane, polyphenylmethylsiloxane, and polydiphenylsiloxane. One type of polyorganosiloxane may be used alone, or two or more types may be used in combination. The reactive functional group may be introduced into one end of the polyorganosiloxane, both ends, or a side chain. Examples of reactive functional groups include alkenyl groups having 2 to 10 carbon atoms. Examples of the alkenyl group include vinyl groups, allyl groups, propenyl groups, butenyl groups, pentenyl groups, hexenyl groups, heptenyl groups, and octenyl groups.

Examples of reactive silicone resins having reactive functional groups include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, X-62-1387, X-62-5039, X-62-5040, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A/B, X-62-7052, X-62-7028A/B, X-62-7619, and X-62-7213 manufactured by Shin-Etsu Chemical Co., Ltd.; and YSR-3022, TPR-6700, TPR-6720, and TPR- 6721, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775, XS56-A2982, XS56-C6010, XS56-C4880, UV9430, TPR6600, TPR6604, TPR6605; SRX357 and SRX211 manufactured by Dow Corning Toray Co., Ltd. Examples include SD7220, SD7292, LTC750A, LTC760A, LTC303E, LTC300B, LTC856, SP7259, BY24-468C, SP7248S, BY24-452, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, and DKQ3-210.

Examples of non-reactive silicone resins having a weight average molecular weight of 400,000 or more include polyorganosiloxanes having a weight average molecular weight of 400,000 or more, and preferably polyorganosiloxanes represented by the following general formula (A).
R ₃ SiO (R ₂ SiO) _n SiR ₃ (A)
(In the formula, each R is independently a hydrocarbon group having no aliphatic unsaturated bond, and n is a positive integer.)

The weight-average molecular weight of the non-reactive silicone resin is preferably 500,000 or more, more preferably 600,000 or more, from the viewpoint of imparting easy releasability to the release layer, and is preferably 1,000,000 or less, more preferably 900,000 or less, from the viewpoint of preventing the release layer from becoming too elastic. The weight-average molecular weight is measured by GPC (gel permeation chromatography) and calculated in polystyrene equivalent terms.

In order to adjust the modulus of elasticity of the release layer to less than 1.5 MPa and impart excellent easy releasability to the release layer, the content of the reactive silicone resin is 50 to 70% by mass and the content of the non-reactive silicone resin is 30 to 50% by mass, based on a total content of 100% by mass of the reactive silicone resin and the non-reactive silicone resin. Preferably, the content of the reactive silicone resin is 55 to 65% by mass and the content of the non-reactive silicone resin is 35 to 45% by mass. More preferably, the content of the reactive silicone resin is 57 to 63% by mass and the content of the non-reactive silicone resin is 37 to 43% by mass.

In addition to the silicone resin, the release layer may also contain a crosslinking agent, a catalyst, a reaction inhibitor, an adhesion improver, etc.

The release layer can be formed, for example, by applying a composition containing the above materials to the substrate film or oligomer blocking layer using a conventional coating method such as reverse gravure coating, bar coating, or die coating, and then curing the composition by heat treatment, typically at approximately 120 to 200°C for 30 seconds to 30 minutes. If necessary, heat treatment and irradiation with active energy rays such as ultraviolet light may be used in combination.

The thickness of the release layer is typically 10 to 2000 nm, preferably 10 to 1000 nm, more preferably 10 to 500 nm, and even more preferably 50 to 300 nm.

From the viewpoint of imparting excellent easy releasability to the release layer, the elastic modulus of the release layer is less than 1.5 MPa, preferably 1.4 MPa or less, more preferably 1.3 MPa or less, and even more preferably 1.2 MPa or less. Furthermore, from the viewpoint of preventing the release layer from falling off, the elastic modulus of the release layer is preferably 0.5 MPa or more, more preferably 0.75 MPa or more, and even more preferably 0.9 MPa or more. The elastic modulus of the release layer is measured by the method described in the examples.

<Oligomer Prevention Layer>
The oligomer blocking layer is a functional layer that prevents oligomers contained in the substrate film from eluting into the pressure-sensitive adhesive layer. The oligomer blocking layer can be formed from an inorganic or organic material, or a composite thereof. Examples of inorganic materials include silica-based materials, metals such as gold, silver, platinum, palladium, copper, aluminum, nickel, chromium, titanium, iron, cobalt, or tin, or alloys thereof, metal oxides such as indium oxide, tin oxide, titanium oxide, cadmium oxide, or mixtures thereof, and other metal compounds such as copper iodide. Examples of organic materials include polyvinyl alcohol-based resins, acrylic resins, urethane-based resins, melamine-based resins, UV-curable resins, and epoxy-based resins. Examples of composite materials include mixtures of the organic materials with inorganic particles such as alumina, silica, or mica.

The oligomer prevention layer is preferably formed from a composition containing a silica-based material and a polyvinyl alcohol-based resin.

<Silica-based materials>
The silica-based material may be, for example, an organosiloxane represented by the following general formula (I).

In the general formula (I), ^R1 and ^R2 are each independently an organic group containing an epoxy group such as a γ-glycidoxypropyl group or a 3,4-epoxycyclohexylethyl group, or an alkoxy group such as a methoxy group or an ethoxy group, and ^R3 is an alkoxy group such as a methoxy group or an ethoxy group, or a group represented by the following general formula (II), where n and m are integers of 0 to 10.

In the general formula (II), ^R4 is the same epoxy group-containing organic group or alkoxy group as ^R1 or ^R2 .

Specific examples of the organosiloxane include monomers such as γ-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 5,6-epoxycyclohexyltriethoxysilane, and tetraethoxysilane, as well as hydrolysis products (oligomers) of these monomers or mixtures of these monomers.

The silica-based material may be a silane compound having an amino group, and the silane compound having an amino group is preferably an alkoxysilane represented by the following general formula (III):
Y-R-Si-(X) ₃ (III)
(In the general formula (III), Y represents an amino group, R represents an alkylene group such as methylene, ethylene, or propylene, and X represents an alkoxy group such as a methoxy group or an ethoxy group, an alkyl group, or an organic functional group having any of these groups, and at least one of them is an alkoxy group.)

Specific examples of silane compounds having an amino group include N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane.

Other examples of the silica-based material include (meth)acrylic group-containing silane compounds such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane, and isocyanate group-containing silane compounds such as 3-isocyanatepropyltriethoxysilane.

Specific examples of the silica-based material include KR-401N, X-40-9227, X-40-9247, KR-510, KR-9218, KR-213, KR-217, X-41-1053, X-40-1056, X-41-1805, X-41-1810, X-40-2651, X-40-2652B, X-40-2655A, X-40-2761, and X-40-2672 manufactured by Shin-Etsu Chemical Co., Ltd.

The silica-based material may be used alone or in combination with two or more types.

The oligomer blocking layer formed from the silica-based material may contain, as necessary, an organic compound containing a metal element (a metal compound such as a metal chelate), a catalyst, etc. Only one type of metal organic compound containing a metal element may be used, or two or more types may be used.

Among the organic metal compounds containing the above-mentioned metal elements, organic compounds containing aluminum, titanium, and zirconium, which have a chelate structure, are preferred because they have particularly good oligomer elution prevention properties. Such compounds are specifically described in the "Crosslinker Handbook" (edited by Yamashita Shinzo and Kaneko Tosuke, Taiseisha Co., Ltd., 1990 edition).

The oligomer blocking layer made of the silica-based material can be formed by dissolving the silica-based material in a solvent such as alcohol, applying the solution to the substrate film, and then drying. The concentration of the solution containing the silica-based material is not particularly limited, but is preferably approximately 0.1 to 40% by weight. The drying temperature after application is not particularly limited, but is preferably approximately 100 to 150°C. The drying time after application is also not particularly limited, but is preferably approximately 30 seconds to 30 minutes.

<Composition containing polyvinyl alcohol-based resin>
The polyvinyl alcohol resin may be polyvinyl alcohol or a derivative thereof. Examples of polyvinyl alcohol derivatives include polyvinyl formal, polyvinyl acetal, etc., as well as those modified with olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and alkyl esters thereof, and acrylamide. Only one type of polyvinyl alcohol resin may be used, or two or more types may be used.

The degree of polymerization of the polyvinyl alcohol resin is not particularly limited, but is typically 100 or higher, preferably 300 to 40,000. On the other hand, the degree of saponification of the polyvinyl alcohol resin is not particularly limited, but is preferably 70 mol% or higher, preferably 80 mol% or higher and 99.9 mol% or lower.

The composition containing the polyvinyl alcohol resin can contain a binder polymer. Examples of binder polymers include polyacrylamide, polyalkylene glycol, polyalkyleneimine, methyl cellulose, hydroxycellulose, starches, polyurethane, polyester, polyacrylate, chlorine-based polymers (such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymer), and polyolefin. Among these, when the oligomer blocking layer is applied by the coating and stretching method, organic polymers that can be used as nonionic, cationic, or amphoteric aqueous solutions or dispersions are recommended. Among these, polyurethane, polyester, and polyacrylate provide excellent adhesion. These polymers can be made hydrophilic and dispersible in water by copolymerizing a nonionic, cationic, or amphoteric hydrophilic component as one of their monomer components.

The composition containing the polyvinyl alcohol resin may contain a crosslinking agent. Examples of crosslinking agents include methylolated or alkylolated urea, melamine, guanamine, acrylamide, and polyamide compounds, epoxy compounds, aziridine compounds, blocked polyisocyanates, silane coupling agents, titanium coupling agents, and zircoaluminate coupling agents. These crosslinking components may be pre-bonded to the binder polymer.

The composition containing the polyvinyl alcohol resin may contain inorganic particles to improve the adhesion and slip properties of the oligomer prevention layer. Examples of inorganic particles include silica, alumina, kaolin, calcium carbonate, titanium oxide, and barium salts.

The oligomer blocking layer can be formed by applying a solution of the polyvinyl alcohol-based resin-containing composition dissolved in a solvent such as water or alcohol to a substrate film and then drying the solution. The solution may be stretched during drying. The concentration of the solution containing the polyvinyl alcohol-based resin-containing composition is not particularly limited, but is preferably approximately 0.1 to 40% by weight. The drying temperature after application is not particularly limited, but is preferably approximately 60 to 200°C. The drying time after application is not particularly limited, but is preferably approximately 3 to 60 seconds. If necessary, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination.

The content of the polyvinyl alcohol resin in the oligomer blocking layer is not particularly limited, but is preferably in the range of 10 to 100% by weight, more preferably 20 to 90% by weight, and most preferably 30 to 80% by weight.

The method for forming the oligomer blocking layer is not particularly limited and may be selected appropriately depending on the material used. Methods that can be used include coating, spraying, spin coating, and in-line coating. Vacuum deposition, sputtering, ion plating, spray pyrolysis, chemical plating, and electroplating can also be used.

The thickness of the oligomer blocking layer is preferably set appropriately in the range of 5 to 100 nm, and more preferably 10 to 70 nm.

<Adhesive Layer>
The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition. Examples of the pressure-sensitive adhesive composition include a rubber-based pressure-sensitive adhesive composition, an acrylic-based pressure-sensitive adhesive composition, a silicone-based pressure-sensitive adhesive composition, a urethane-based pressure-sensitive adhesive composition, a vinyl alkyl ether-based pressure-sensitive adhesive composition, a polyvinyl alcohol-based pressure-sensitive adhesive composition, a polyvinylpyrrolidone-based pressure-sensitive adhesive composition, a polyacrylamide-based pressure-sensitive adhesive composition, and a cellulose-based pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition preferably contains a base polymer.

<Base polymer>
The base polymer is selected from adhesive base polymers depending on the type of the adhesive composition.

From the viewpoint of improving the reworkability of the pressure-sensitive adhesive layer and reducing the peeling force when peeling the separator from the pressure-sensitive adhesive layer, the base polymer preferably contains less than 0.5% by mass of carboxyl group-containing monomers as monomer units, preferably 0.3% by mass or less, more preferably 0.2% by mass or less, and even more preferably 0% by mass, i.e., no carboxyl group-containing monomers.

Among the above-mentioned pressure-sensitive adhesive compositions, acrylic pressure-sensitive adhesive compositions are preferred because they have excellent optical transparency, exhibit appropriate adhesive properties such as wettability, cohesion, and adhesion, and are excellent in weather resistance and heat resistance. Acrylic pressure-sensitive adhesive compositions preferably contain a (meth)acrylic polymer as the adhesive base polymer. (Meth)acrylic polymers typically contain alkyl (meth)acrylate as a main component as a monomer unit. Note that (meth)acrylate refers to acrylate and/or methacrylate, and (meth) in the present invention has the same meaning.

Examples of the alkyl (meth)acrylate that constitutes the main skeleton of the (meth)acrylic polymer include linear or branched alkyl groups having 1 to 18 carbon atoms. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. Only one type of alkyl (meth)acrylate may be used, or two or more types may be used. The average carbon number of these alkyl groups is preferably 3 to 9.

Alkyl (meth)acrylates containing aromatic rings, such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate, can be used as the alkyl (meth)acrylate from the standpoints of adhesive properties, durability, retardation adjustment, refractive index adjustment, etc.

In order to improve adhesion and heat resistance, one or more copolymerizable monomers having a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, can be introduced into the (meth)acrylic polymer by copolymerization. Specific examples of copolymerizable monomers include hydroxy group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate; (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate. Examples include carboxyl group-containing monomers such as acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate.

As described above, the (meth)acrylic polymer contains less than 0.5 mass% of the carboxy group-containing monomer as monomer units from the viewpoints of improving the reworkability of the pressure-sensitive adhesive layer and reducing the peel force when peeling the separator from the pressure-sensitive adhesive layer. The preferred content is as described above.

The (meth)acrylic polymer contains alkyl (meth)acrylate as the main component in the mass ratio of all constituent monomers. The proportion of the copolymerizable monomer is not particularly limited, but is preferably approximately 0 to 20%, approximately 0.1 to 15%, or even approximately 0.1 to 10% in the mass ratio of all constituent monomers.

The (meth)acrylic polymer typically has a weight-average molecular weight (Mw) in the range of 500,000 to 3,000,000. Considering durability, particularly heat resistance, it is preferable to use a weight-average molecular weight (Mw) of 700,000 to 2,700,000, and more preferably 800,000 to 2,500,000. A weight-average molecular weight (Mw) of less than 500,000 is undesirable in terms of heat resistance. Furthermore, a weight-average molecular weight (Mw) greater than 3,000,000 is undesirable because a large amount of dilution solvent is required to adjust the viscosity for application, resulting in increased costs. The weight-average molecular weight (Mw) is measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

The (meth)acrylic polymer can be produced by any known production method, such as solution polymerization, bulk polymerization, emulsion polymerization, or various radical polymerizations. Furthermore, the resulting (meth)acrylic polymer may be a random copolymer, block copolymer, graft copolymer, or the like.

The polymerization initiator, chain transfer agent, emulsifier, etc. used in the radical polymerization are not particularly limited and can be selected as appropriate. The weight-average molecular weight (Mw) of the (meth)acrylic polymer can be controlled by the amounts of polymerization initiator and chain transfer agent used and the reaction conditions, and the amounts used are adjusted appropriately depending on the type of these.

In the solution polymerization, ethyl acetate, toluene, or the like is used as the polymerization solvent. In a specific example of solution polymerization, the reaction is carried out under a stream of inert gas such as nitrogen, with the addition of a polymerization initiator, typically at about 50 to 70°C, for about 5 to 30 hours.

<Conductive agent>
The pressure-sensitive adhesive composition contains, in addition to the base polymer, a conductive agent, such as an ionic compound, an ionic surfactant, a conductive polymer, or a metal oxide.

As the ionic compound, alkali metal salts and/or organic cation-anion salts can be preferably used. The use of alkali metal salts can effectively reduce the surface resistance of the pressure-sensitive adhesive layer. Furthermore, the use of organic cation-anion salts not only reduces the surface resistance of the pressure-sensitive adhesive layer, but also improves the easy peelability of the separator due to their large molecular size. The alkali metal salts can be organic or inorganic salts of alkali metals. In this specification, "organic cation-anion salt" refers to an organic salt whose cation moiety is composed of an organic substance, and whose anion moiety may be either organic or inorganic. "Organic cation-anion salts" are also referred to as ionic liquids or ionic solids. Only one type of ionic compound may be used, or two or more types may be used.

Examples of alkali metal ions that make up the cation portion of the alkali metal salt include lithium, sodium, and potassium ions. Of these alkali metal ions, lithium ions are preferred.

The anion moiety of the alkali metal salt may be composed of an organic substance or an inorganic substance. Examples of the anion moiety constituting the organic salt include _{CH3COO- ,} ^CF3COO- , _CH3SO3- , ^CF3SO3- , ⁽ _CF3SO2 ) _{3C- , C4F9SO3-} , ^{C3F7COO- ,} ( ^CF3SO2 )( _CF3CO ) ^N- _{, -O3S ( CF2 ) 3SO3-} ^{, PF6- ,} _CO32- , _{and the} ^anions represented _{by the} following general formulas ⁽ ₁ ) to _{( 4 )} :
(1): (CnF _2n+1 SO ₂ ) ₂ N ⁻ (where n is an integer from 1 to 10),
(2): CF ₂ (C _m F _{2 m} SO ₂ ) ₂ N ⁻ (wherein m is an integer of 1 to 10);
(3): ^- O ₃ S(CF ₂ ) _l SO ₃ ^- (where l is an integer from 1 to 10),
(4): (C _p F _2p+1 SO ₂ )N ⁻ (C _q F _2q+1 SO ₂ ), (where p and q are integers of 1 to 10), and the like are used. In particular, an anion moiety containing a fluorine atom is preferably used because it gives an ionic compound with good ionic dissociation properties. Examples of an anion moiety that constitutes an inorganic salt include Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , (CN) ₂ N ⁻ , and the like. As the anion moiety, (perfluoroalkylsulfonyl)imides represented by the general formula (1), such as (CF ₃ SO ₂ ) ₂ N ⁻ and (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , are preferred, and (trifluoromethanesulfonyl)imides represented by (CF ₃ SO ₂ ) ₂ N ⁻ are particularly preferred.

Specific examples of organic salts of alkali metals include sodium acetate, sodium alginate, sodium lignosulfonate, sodium toluenesulfonate, _LiCF3SO3 , Li( _CF3SO2 ) _2N , Li( _C2F5SO2 ) _2N , Li( _C4F9SO2 ) _2N , Li( _CF3SO2 ) _3C , _{KO3S ( CF2 ) 3SO3K} , _{and LiO3S} ( _CF2 ) _{3SO3K .} Of these _{, LiCF3SO3 , Li ( CF3SO2 )2N , Li} ( _{C2F5SO2 ) 2N , and} Li _{( C4F9SO2 ) 2} N, Li( _CF3SO2 ) _{3C ,} etc. are preferred, fluorine _{-containing lithium imide salts such as Li(CF3SO2)2N, Li(C2F5SO2 )2N, and Li(C4F9SO2)2N are more preferred , and ( perfluoroalkylsulfonyl ) imide} lithium salts are particularly preferred.

Furthermore, examples of inorganic salts of alkali metals include lithium perchlorate and lithium iodide.

The organic cation-anion salt is composed of a cation component and an anion component, and the cation component is an organic substance. Specific examples of the cation component include pyridinium cation, piperidinium cation, pyrrolidinium cation, cations having a pyrroline skeleton, cations having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, pyrazolium cation, pyrazolinium cation, tetraalkylammonium cation, trialkylsulfonium cation, and tetraalkylphosphonium cation.

Examples of the anion components include Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , C ₃ F ₇ COO ⁻ , ((CF ₃ SO ₂ )(CF ₃ CO)N ⁻ , ^−O ₃ S(CF ₂ ) ₃ SO ₃ ⁻ , or the following general formulas (1) to (4):
(1): (CnF _2n+1 SO ₂ ) ₂ N ⁻ (where n is an integer from 1 to 10),
(2): CF ₂ (C _m F _{2 m} SO ₂ ) ₂ N ⁻ (wherein m is an integer of 1 to 10);
(3): ^- O ₃ S(CF ₂ ) _l SO ₃ ^- (where l is an integer from 1 to 10),
(4): (C _p F _2p+1 SO ₂ )N ⁻ (C _q F _2q+1 SO ₂ ), where p and q are integers of 1 to 10, are used. Among these, an anion component containing a fluorine atom is preferably used because it gives an ionic compound with good ionic dissociation properties.

In addition to the alkali metal salts and organic cation-anion salts, examples of the ionic compounds include inorganic salts such as ammonium chloride, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, and ammonium sulfate.

Examples of the ionic surfactant include cationic surfactants (quaternary ammonium salt type, phosphonium salt type, sulfonium salt type, etc.), anionic surfactants (carboxylic acid type, sulfonate type, sulfate type, phosphate type, phosphite type, etc.), amphoteric surfactants (sulfobetaine type, alkylbetaine type, alkylimidazolium betaine type, etc.), and nonionic surfactants (polyhydric alcohol derivatives, β-cyclodextrin inclusion compounds, sorbitan fatty acid monoesters and diesters, polyalkylene oxide derivatives, amine oxides, etc.). Ionic surfactants may be used alone or in combination of two or more types.

Examples of the conductive polymer include polyaniline, polythiophene, polypyrrole, and polyquinoxaline polymers. Of these, polyaniline and polythiophene are preferred, as they are easily converted into water-soluble or water-dispersible conductive polymers. Polythiophene is particularly preferred. Only one type of conductive polymer may be used, or two or more types may be used.

Examples of the metal oxide include tin oxide, antimony oxide, indium oxide, and zinc oxide. Of these, tin oxide is preferred. Examples of tin oxide include tin oxide, antimony-doped tin oxide, indium-doped tin oxide, aluminum-doped tin oxide, tungsten-doped tin oxide, a titanium oxide-cerium oxide-tin oxide composite, and a titanium oxide-tin oxide composite. Only one type of metal oxide may be used, or two or more types may be used.

Further examples of conductive agents other than those mentioned above include acetylene black, ketjen black, natural graphite, artificial graphite, titanium black, homopolymers of monomers having ionic conductive groups of the cationic type (quaternary ammonium salts, etc.), amphoteric type (betaine compounds, etc.), anionic type (sulfonates, etc.), or nonionic type (glycerin, etc.), or copolymers of such monomers with other monomers, ionic conductive polymers such as polymers having moieties derived from acrylates or methacrylates having quaternary ammonium salt groups, and permanent antistatic agents in which hydrophilic polymers such as polyethylene methacrylate copolymers are alloyed with acrylic resins, etc.

It is preferable to use an ionic compound as the conductive agent, as it has high conductivity, excellent dispersibility and transparency in the adhesive, and storage stability in the adhesive.

The blending ratio of the conductive agent is preferably 0.0001 to 10 parts by weight per 100 parts by weight of base polymer. If the amount of conductive agent is less than 0.0001 parts by weight, the antistatic performance may not be sufficiently improved. On the other hand, if the amount of conductive agent is more than 10 parts by weight, durability may not be sufficient. The amount of conductive agent is preferably 0.01 parts by weight or more, and more preferably 0.1 parts by weight or more. The amount of conductive agent is also preferably 8 parts by weight or less, and more preferably 6 parts by weight or less.

The pressure-sensitive adhesive composition may further contain a crosslinking agent. Examples of crosslinking agents that can be used include organic crosslinking agents and polyfunctional metal chelates. Examples of organic crosslinking agents include isocyanate-based crosslinking agents, peroxide-based crosslinking agents, epoxy-based crosslinking agents, and imine-based crosslinking agents. Polyfunctional metal chelates are compounds in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Examples of atoms in the organic compound that form covalent or coordinate bonds include oxygen atoms. Examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds. Examples of crosslinking agents that can be used include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. Only one type of crosslinking agent may be used, or two or more types may be used.

The blending ratio of the crosslinking agent is preferably 0.01 to 20 parts by mass, and more preferably 0.03 to 10 parts by mass, per 100 parts by mass of base polymer. If the crosslinking agent is less than 0.01 part by mass, the adhesive tends to have insufficient cohesive strength and may foam when heated. On the other hand, if the crosslinking agent is more than 20 parts by mass, moisture resistance may be insufficient, and peeling may occur during reliability tests, etc.

The pressure-sensitive adhesive composition may further contain a silane coupling agent. Use of a silane coupling agent can improve durability. Only one type of silane coupling agent may be used, or two or more types may be used.

The blending ratio of the silane coupling agent is preferably 0.001 to 5 parts by mass, more preferably 0.01 to 1 part by mass, even more preferably 0.02 to 1 part by mass, and particularly preferably 0.05 to 0.6 parts by mass, per 100 parts by mass of base polymer. The blending ratio is selected appropriately within this range to improve durability and maintain adequate adhesive strength to optical components such as liquid crystal panels.

The pressure-sensitive adhesive composition may also contain other known additives, such as colorants, powders such as pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particulate or foil-like materials, etc., which can be added as appropriate depending on the intended use. Furthermore, a redox system may also be used by adding a reducing agent, within controllable limits.

The separator-attached pressure-sensitive adhesive layer can be produced by applying a solution containing the pressure-sensitive adhesive composition to the release layer of the separator and then drying to form a pressure-sensitive adhesive layer. When applying the pressure-sensitive adhesive composition, one or more additional solvents other than the polymerization solvent may be added as appropriate.

Various methods can be used to apply the pressure-sensitive adhesive composition. Specific examples include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and extrusion coating using a die coater, etc.

The thickness of the pressure-sensitive adhesive layer is not particularly limited and is approximately 1 to 100 μm. It is preferably 2 to 50 μm, more preferably 2 to 40 μm, and even more preferably 5 to 35 μm.

From the viewpoint of imparting conductivity to the separator-attached pressure-sensitive adhesive layer and suppressing white unevenness in the liquid crystal panel, the surface resistance value of the pressure-sensitive adhesive layer is preferably 1.0×10 ¹² Ω/□ or less, more preferably 1.0×10 ¹¹ Ω/□ or less, and even more preferably 1.0×10 ¹⁰ Ω/□ or less.

From the viewpoint of reworkability, the adhesive strength of the adhesive layer is preferably 8 N/25 mm or less, more preferably 6 N/25 mm or less, and even more preferably 4 N/25 mm or less.

<Polarizing film with separator and pressure-sensitive adhesive layer>
The separator-containing pressure-sensitive adhesive layer-attached polarizing film of the present invention is one in which the pressure-sensitive adhesive layer side of the separator-attached pressure-sensitive adhesive layer is attached to one or both surfaces of a polarizing film.

The polarizing film typically has a transparent protective film on one or both sides of the polarizer. There are no particular limitations on the polarizer, and various types can be used. Examples of polarizers include those obtained by uniaxially stretching a hydrophilic polymer film, such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or a partially saponified ethylene-vinyl acetate copolymer film, onto which a dichroic substance such as iodine or a dichroic dye has been adsorbed, and polyene-based oriented films, such as dehydrated polyvinyl alcohol or dehydrochlorinated polyvinyl chloride. Among these, polarizers made of a polyvinyl alcohol film and a dichroic substance such as iodine, are preferred. There are no particular limitations on the thickness of these polarizers, but they are generally approximately 80 μm or less.

The polarizer may be a thin polarizer having a thickness of 10 μm or less. From the perspective of thinning, the thickness is preferably 1 to 7 μm. Such thin polarizers have little thickness variation, excellent visibility, and excellent durability due to little dimensional change. Furthermore, they are preferable in that they can be used to reduce the thickness of the polarizing film.

The transparent protective film is made of a thermoplastic resin that exhibits excellent transparency, mechanical strength, thermal stability, moisture-blocking properties, and isotropy. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is attached to one side of the polarizer via an adhesive layer, while the other side of the film may be made of a thermosetting resin or ultraviolet-curable resin, such as a (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone-based resin. The transparent protective film may contain one or more suitable additives.

The adhesive used to bond the polarizer and transparent protective film is not particularly limited as long as it is optically transparent, and various types of adhesives such as water-based, solvent-based, hot-melt, radical-curing, and cationic-curing types can be used, but water-based or radical-curing adhesives are preferred.

From the perspective of achieving a thinner film, the thickness of the polarizing film is preferably 75 μm or less, more preferably 65 μm or less, and even more preferably 60 μm or less.

In the polarizing film with a pressure-sensitive adhesive layer having a separator of the present invention, the peel force required to peel the separator from the pressure-sensitive adhesive layer is preferably 0.09 N/50 mm or less, more preferably 0.08 N/50 mm or less, even more preferably 0.07 N/50 mm or less, and even more preferably 0.06 N/50 mm or less, from the viewpoint of easy peelability of the separator.

The polarized film with an adhesive layer and separator of the present invention has conductive properties and an adhesive layer with excellent reworkability and durability, making it suitable for use in mobile image display devices, etc.

Examples of the present invention are described below, but the present invention is not limited to these.

<Preparation of Polarizer: Thickness 12 μm>
A 30 μm-thick polyvinyl alcohol film with an average degree of polymerization of 2400 and a degree of saponification of 99.9 mol% was immersed in warm water at 30°C and uniaxially stretched while swelling to 2.0 times its original length. The film was then immersed in a 0.3 wt% iodine solution (weight ratio: iodine/potassium iodide = 0.5/8) at 30°C and dyed while uniaxially stretching to 3.0 times its original length. The film was then stretched in an aqueous solution of 4 wt% hexaboric acid and 5 wt% potassium iodide to 6 times its original length. The film was then impregnated with iodine ions in an aqueous solution of 3 wt% potassium iodide (iodine impregnation bath) and dried in an oven at 60°C for 4 minutes to obtain a 12 μm-thick polarizer.

<First Transparent Protective Film>
A 25 μm-thick triacetyl cellulose film that had been subjected to a saponification treatment was used as the substrate film. The moisture permeability of the substrate film was 1200 g/ ^m² ·24 h. A coating liquid with a solids concentration of 25 wt% obtained by dispersing an acrylic hard coat resin (Unidic 17-813, manufactured by Dainippon Ink and Chemicals, Inc.) in isopropyl alcohol was applied to one side of the substrate film, dried at 80°C for 2 minutes, and then treated with ultraviolet light to form a 7 μm-thick hard coat layer (pencil hardness 3H). The resulting transparent protective film with a surface treatment layer had a thickness of 32 μm and a moisture permeability of 400 g/ ^m² ·24 h.

<Second Transparent Protective Film>
A 13 μm thick cyclic polyolefin film (ZEONOR manufactured by Zeon Corporation) was subjected to corona treatment and used. The moisture permeability of the film was 12 g/m ² ·24 h.

<Moisture permeability>
Measurement was carried out based on the moisture permeability test method (cup method) for moisture-proof packaging materials described in JIS Z0208.

<Preparation of Polarizing Film>
A polyvinyl alcohol-based adhesive was applied to both sides of the polarizer (thickness: 12 μm) so that the thickness of the aqueous adhesive layer was 0.1 μm, and the first transparent protective film (the side without the surface treatment layer) and the second transparent protective film were bonded to each other. The resulting film was then dried at 50°C for 5 minutes to produce a polarized film (thickness: 57 μm).

<Preparation of Acrylic Polymer Solution (A)>
A solution was prepared by adding 100 parts of butyl acrylate, 5 parts of acrylic acid, 0.075 parts of 2-hydroxyethyl acrylate, and 0.3 parts of 2,2'-azobisisobutyronitrile together with ethyl acetate to a reaction vessel equipped with a condenser, a nitrogen inlet tube, a thermometer, and a stirrer. This solution was then stirred while blowing in nitrogen gas, and reacted at 60°C for 4 hours to obtain a solution containing an acrylic polymer having a weight-average molecular weight of 2,200,000. Further, ethyl acetate was added to this solution containing the acrylic polymer to adjust the solids concentration to 30%, thereby obtaining acrylic polymer solution (A).

<Preparation of Pressure-Sensitive Adhesive Compositions (A-1) to (A-3)>
A pressure-sensitive adhesive composition (A-1) was prepared by blending, in this order, 0.6 parts of a crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L") mainly composed of a compound having an isocyanate group as a crosslinking agent, 0.075 parts of γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KMB-403") as a silane coupling agent, and 0.3 parts of lithium bis(trifluoromethanesulfonyl)imide (LiTFSi, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) as an alkali metal salt, relative to 100 parts of the solid content of the acrylic polymer solution (A), and a pressure-sensitive adhesive composition (A-2) and a pressure-sensitive adhesive composition (A-3) were prepared in the same manner as above, except that the amount of LiTFSi blended was changed to 3 parts and 6 parts, respectively.

<Preparation of Acrylic Polymer Solution (B)>
A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with a monomer mixture containing 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator was charged together with ethyl acetate for 100 parts of the monomer mixture (solid content). Nitrogen gas was introduced with gentle stirring to replace the atmosphere with nitrogen, and the liquid temperature in the flask was maintained at around 60°C, allowing the polymerization reaction to proceed for 7 hours. Ethyl acetate was then added to the resulting reaction solution to prepare a solution (B) containing an acrylic polymer with a weight-average molecular weight of 1,400,000, with a solid content adjusted to 30%.

<Preparation of Pressure-Sensitive Adhesive Compositions (B-1) to (B-4)>
Per 100 parts of the solids content of the acrylic polymer solution (B), 0.3 parts of ethylmethylpyrrolidinium-bis(trifluoromethanesulfonyl)imide (EMPTFSi, manufactured by Tokyo Chemical Industry Co., Ltd.) as an onium-anion salt, 0.095 parts of trimethylolpropane xylylene diisocyanate (trade name: Takenate D110N, manufactured by Mitsui Chemicals, Inc.) as a crosslinking agent, 0.3 parts of dibenzoyl peroxide (trade name: Niper BMT40SV, manufactured by Nippon Oil & Fats Co., Ltd.), and 0.2 parts of an acetoacetyl group-containing silane coupling agent (trade name: A-100, manufactured by Soken Chemical & Engineering Co., Ltd.) were blended to prepare a pressure-sensitive adhesive composition (B-1). Further, pressure-sensitive adhesive compositions (B-2) to (B-4) were prepared in the same manner as above, except that the amount of EMPTFSi blended was changed to 3 parts, 6 parts, and 0.

<Preparation of Acrylic Polymer Solution (C)>
A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with a monomer mixture containing 79.7 parts of butyl acrylate, 16 parts of phenoxyethyl acrylate, 3 parts of N-vinyl-2-pyrrolidone, 0.3 parts of acrylic acid, and 1 part of 4-hydroxybutyl acrylate. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts of ethyl acetate were charged relative to 100 parts of the monomer mixture (solid content). Nitrogen gas was introduced with gentle stirring to replace the atmosphere with nitrogen, and the liquid temperature in the flask was maintained at around 55°C, allowing the polymerization reaction to proceed for 8 hours to prepare a solution (C) containing an acrylic polymer having a weight average molecular weight (Mw) of 1,800,000.

<Preparation of Pressure-Sensitive Adhesive Compositions (C-1) to (C-4)>
Per 100 parts of the solids of the acrylic polymer solution (C), an isocyanate crosslinking agent (Takenate D160N manufactured by Mitsui Chemicals, Inc., trimethylolpropane hexamethylene diisocyanate) 0.2 parts, benzoyl peroxide (Niper BMT manufactured by NOF Corporation) 0.2 parts, as an alkali metal salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSi, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) 0.3 parts, and an acetoacetyl group-containing silane coupling agent (trade name: A-100, manufactured by Soken Chemical & Engineering Co., Ltd.) 0.2 parts were blended to prepare a pressure-sensitive adhesive composition (C-1). Further, pressure-sensitive adhesive compositions (C-2) to (C-4) were prepared in the same manner as above, except that the amount of LiTFSi blended was changed to 3 parts, 6 parts, and 0 parts.

<Preparation of Pressure-Sensitive Adhesive Compositions (C-5) to (C-7)>
Per 100 parts of the solids content of the acrylic polymer solution (C), 0.2 parts of an isocyanate crosslinking agent (Takenate D160N manufactured by Mitsui Chemicals, Inc., trimethylolpropane hexamethylene diisocyanate), 0.2 parts of benzoyl peroxide (Niper BMT manufactured by NOF Corporation), 0.3 parts of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (AS-110 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as an onium-anion salt, and 0.2 parts of an acetoacetyl group-containing silane coupling agent (trade name: A-100 manufactured by Soken Chemical & Engineering Co., Ltd.) were blended to prepare an acrylic pressure-sensitive adhesive composition (C-5). Furthermore, pressure-sensitive adhesive compositions (C-6) and (C-7) were prepared in the same manner as above, except that the amount of AS-110 blended was changed to 3 parts and 6 parts, respectively.

<Preparation of Separator X>
[Formation of Oligomer Blocking Layer]
A coating solution was prepared by diluting organosiloxane (Ethyl Silicate 48: Colcoat Co., Ltd.) as a silica-based material with isopropyl alcohol to a solids concentration of 1%. The resulting coating solution was applied to a polyester film (thickness: 38 μm) as a substrate film using a gravure coater so as to have a thickness of 50 nm after drying, and then dried at 120° C. for 30 seconds to form an oligomer blocking layer.

[Formation of Release Layer]
20 parts of a reactive silicone resin having a reactive functional group (LTC856: manufactured by Dow Corning Toray), 13.5 parts of a non-reactive silicone resin having a weight average molecular weight of 400,000 (BY24-850: manufactured by Dow Corning Toray), and 0.2 parts of a curing agent (SRX-212cat: manufactured by Dow Corning Toray) were diluted with 350 parts of a methyl ethyl ketone/toluene mixed solvent (mixing ratio 1:1) to prepare a silicone-based release agent solution. The obtained silicone-based release agent solution was applied to the oligomer prevention layer using a gravure coater so that the thickness after drying was 120 nm, and then dried at 120 ° C. for 30 seconds to form a release layer. A separator X having a polyester film/oligomer prevention layer/release layer configuration was produced. In the formed release layer, the content of the reactive silicone resin is 60% by mass and the content of the non-reactive silicone resin is 40% by mass, with the total content of the reactive silicone resin and the non-reactive silicone resin being 100% by mass.

<Preparation of Separator Y>
[Formation of Oligomer Blocking Layer]
A coating solution was prepared by diluting organosiloxane (Ethyl Silicate 48: Colcoat Co., Ltd.) as a silica-based material with isopropyl alcohol to a solids concentration of 1%. The resulting coating solution was applied to a polyester film (thickness: 38 μm) as a substrate film using a gravure coater so as to have a thickness of 50 nm after drying, and then dried at 120° C. for 30 seconds to form an oligomer blocking layer.

[Formation of Release Layer]
A solution of a silicone-based release agent was prepared by diluting 20 parts of a reactive silicone resin having a reactive functional group (KS-847H, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.2 parts of a curing agent (PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.) with 350 parts of a methyl ethyl ketone/toluene mixed solvent (mixing ratio 1:1). The obtained silicone-based release agent solution was applied to the oligomer blocking layer using a gravure coater so that the thickness after drying would be 100 nm, and then dried at 120°C for 30 seconds to form a release layer, thereby producing a separator Y having a configuration of polyester film/oligomer blocking layer/release layer.

Example 1
<Preparation of a polarizing film with a separator and pressure-sensitive adhesive layer>
The pressure-sensitive adhesive composition (C-1) was uniformly applied to the surface of the release layer of separator X using a fountain coater, and then dried for 2 minutes in an air-circulating constant-temperature oven at 155°C to form a pressure-sensitive adhesive layer with a thickness of 20 µm, thereby producing a pressure-sensitive adhesive layer with a separator. Next, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer with a separator prepared was attached to the second transparent protective film of the prepared polarizing film, thereby producing a polarizing film with a pressure-sensitive adhesive layer having a separator.

Examples 2 to 9, Comparative Examples 1 to 15
<Preparation of a polarizing film with a separator and pressure-sensitive adhesive layer>
A polarizing film with a pressure-sensitive adhesive layer having a separator was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive composition and separator shown in Table 1 were used.

<Measurement and evaluation methods>
(Elastic modulus of release layer)
The substrate film side of the prepared separator was attached to a stainless steel sample stage using double-sided adhesive tape. Subsequently, a force curve measurement was performed on the release layer side of the separator at 1 Hz using a probe microscope (Oxford Instruments, product name "Asylum Research MFP-3D-SA") equipped with a silicon probe (Olympus, product name "AC240TS", radius of curvature: 10 nm, spring constant: equivalent to 3 N/m) to obtain a load-displacement curve. The elastic modulus (MPa) of the release layer was calculated from the obtained load-displacement curve using the JKR two-point method.

(adhesive strength)
The prepared polarizing film with the pressure-sensitive adhesive layer was cut into a size of 120 mm length x 25 mm width to prepare a sample. The sample was attached to a 0.7 mm thick alkali-free glass plate (EG-XG, manufactured by Corning Incorporated) using a laminator and then autoclaved at 50°C and 5 atm for 15 minutes to ensure complete adhesion. The adhesive strength of the sample was then measured. The adhesive strength was determined by measuring the adhesive strength (N/25 mm, measurement length 80 mm) when the sample was peeled off at a peel angle of 90° and a peel rate of 300 mm/min using a tensile tester (Shimazu Autograph AG-1 1OKN). The measurement was performed 200 times at intervals of 0.5 s, and the average value was used as the measured value. Three samples were used. Evaluation was based on the following criteria.
◎: 3.9 or less ◯: More than 3.9 but less than 6 △: 6 or more but less than 8 ×: 8 or more

(Separator peeling force)
The prepared polarizing film with a separator and pressure-sensitive adhesive layer was cut into a size of 50 mm x 100 mm to prepare a measurement sample. The measurement sample was attached, with the surface-treated side facing down, to a flat peeling jig via double-sided pressure-sensitive adhesive tape. The separator was then peeled 10 mm from the surface of the pressure-sensitive adhesive layer. The peeled separator was then chucked and pulled using a tensile tester to measure the peel force (N/50 mm) (pulling direction: 180° relative to the surface of the polarizing film, tensile speed: 300 mm/min). 200 samples were taken at intervals of 0.5 s, and the average value was used as the measurement value. Three samples were used. Evaluation was based on the following criteria.
◯: 0.07 or less △: More than 0.07 but less than 0.10 ×: 0.10 or more

(Surface resistance value of pressure-sensitive adhesive layer)
The surface resistance value (Ω/□) of the pressure-sensitive adhesive layer was measured using MCP-HT450 manufactured by Mitsubishi Chemical Analytech Co., Ltd. The surface resistance value was evaluated according to the following criteria.
〇: 10 ¹⁰ or less △: 10 ¹¹ to 10 ¹²
×: Over

Table 1 shows that the adhesive layer-attached polarizing films having separators of Examples 1 to 9 have a low elastic modulus of the release layer, low peel force when peeling the separator from the adhesive layer, and low adhesive strength of the adhesive layer, resulting in excellent separator releasability and reworkability of the adhesive layer. On the other hand, the adhesive layer-attached polarizing films having separators of Comparative Examples 1 to 15 have a high elastic modulus of the release layer, high peel force when peeling the separator from the adhesive layer, resulting in poor separator releasability. Furthermore, the adhesive layer-attached polarizing films having separators of Comparative Examples 1 to 5 have a high content of carboxyl group-containing monomer in the base polymer of the adhesive layer, resulting in high adhesive strength of the adhesive layer and poor reworkability.

The polarizing film with a pressure-sensitive adhesive layer having the separator of the present invention is suitable for use in image display devices, such as mobile image display devices.

Claims (6)

A polarizing film with a separator and a pressure-sensitive adhesive layer, in which a separator-attached pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer on a separator is provided on one or both sides of the polarizing film,
the separator has a release layer on a substrate film,
the release layer contains a reactive silicone resin having a reactive functional group and a non-reactive silicone resin having a weight average molecular weight of 400,000 or more;
the reactive functional group is an alkenyl group having 2 to 10 carbon atoms,
the content of the reactive silicone resin is 50 to 70 mass% and the content of the non-reactive silicone resin is 30 to 50 mass% relative to 100 mass% of the total content of the reactive silicone resin and the non-reactive silicone resin;
The release layer has an elastic modulus of less than 1.5 MPa,
the pressure-sensitive adhesive layer is provided on the release layer,
the pressure-sensitive adhesive layer contains a conductive agent,
A polarizing film with a separator and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer contains a base polymer containing less than 0.5% by mass of a carboxyl group-containing monomer as a monomer unit. The polarized film with a pressure-sensitive adhesive layer and separator according to claim 1, wherein the conductive agent is an alkali metal salt and/or an organic cation-anion salt. 3. A polarized film with a pressure-sensitive adhesive layer comprising the separator according to claim 1, wherein the pressure-sensitive adhesive layer has a surface resistance value of 1.0×10 ¹² Ω/□ or less. A polarized film with a pressure-sensitive adhesive layer having the separator according to any one of claims 1 to 3, wherein the peel force required to peel the separator from the pressure-sensitive adhesive layer is 0.09 N/50 mm or less. A polarized film with an adhesive layer having the separator according to any one of claims 1 to 4, wherein the adhesive strength of the adhesive layer is 8 N/25 mm or less. A polarizing film with a pressure-sensitive adhesive layer, comprising the separator according to any one of claims 1 to 5, wherein the polarizing film has a thickness of 75 µm or less.