WO2016059979A1 - 粘着剤層、粘着剤層付き偏光板および積層体 - Google Patents
粘着剤層、粘着剤層付き偏光板および積層体 Download PDFInfo
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- WO2016059979A1 WO2016059979A1 PCT/JP2015/078059 JP2015078059W WO2016059979A1 WO 2016059979 A1 WO2016059979 A1 WO 2016059979A1 JP 2015078059 W JP2015078059 W JP 2015078059W WO 2016059979 A1 WO2016059979 A1 WO 2016059979A1
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- adhesive layer
- mass
- sensitive adhesive
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- film
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
- C09J133/04—Homopolymers or copolymers of esters
- C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09J133/08—Homopolymers or copolymers of acrylic acid esters
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/02—Non-macromolecular additives
- C09J11/06—Non-macromolecular additives organic
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J201/00—Adhesives based on unspecified macromolecular compounds
- C09J201/02—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
- C09J201/06—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups containing oxygen atoms
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J201/00—Adhesives based on unspecified macromolecular compounds
- C09J201/02—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
- C09J201/06—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups containing oxygen atoms
- C09J201/08—Carboxyl groups
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
Definitions
- the present invention relates to a pressure-sensitive adhesive layer, a polarizing plate with a pressure-sensitive adhesive layer, and a laminate.
- image display devices are sometimes used not only for indoor use but also as part of in-vehicle monitors and field measurement devices.
- An optical film such as a polarizing film to be bonded to an image display device is produced by adsorbing a polarizing component such as a dichroic dye on a polymer film such as polyvinyl alcohol, and stretching and orienting it.
- a protective film is usually provided on the surface of the polyvinyl alcohol film.
- a triacetyl cellulose (TAC) film has been often used as a protective film for a polyvinyl alcohol film. It is known that the TAC film has a high hygroscopic property, and the TAC film is deformed due to an environmental difference between a high humidity heat condition and room temperature, and the entire polarizing plate is deformed accordingly. Moreover, since the polarizing plate is brittle, it is known that there is a problem that a crack occurs when the polarizing plate is deformed.
- a polycycloolefin-based (COP) film has been used in place of a TAC film as a protective film for a polyvinyl alcohol film in an image device that requires durability.
- the COP film has an advantage that it is less brittle and hygroscopic than the TAC film.
- the COP film is required to have high durability for suppressing the shrinkage of the entire polarizing plate caused by the shrinkage of the polyvinyl alcohol film and the performance of suppressing the “light leakage” of the image display device caused by the shrinkage of the polyvinyl alcohol film.
- the COP film has physical properties different from those of the TAC film, when a conventional pressure-sensitive adhesive used for adhesion between the TAC film and the adherend is used for adhesion between the COP film and the adherend, adhesion is reduced. There is a problem of being bad.
- Patent Document 1 discloses an acrylic pressure-sensitive adhesive composition containing a nuclear hydrogenated terpene phenol resin for the purpose of improving the fixability to polyolefin and cyclic polyolefin in a high temperature atmosphere. Yes.
- the pressure-sensitive adhesive layer obtained from the acrylic pressure-sensitive adhesive composition is used for a polarizing plate, the performance of suppressing light leakage is not sufficient.
- Patent Document 2 discloses a low-polarity film pressure-sensitive adhesive containing a high molecular weight polymer obtained by copolymerizing a monomer component containing an alicyclic monomer or an aromatic ring-containing monomer.
- the pressure-sensitive adhesive has insufficient durability and adhesion to a COP film.
- the object of the present invention is to exhibit excellent durability under high-temperature conditions and high-humidity conditions, reduce light leakage, and adhesion between the glass substrate and the polarizing plate whose protective film is a polycycloolefin film, And it is providing the adhesive layer excellent in adhesiveness with optical films, such as the said polarizing plate and retardation film.
- the contact angle between the pressure-sensitive adhesive layer surface and water is 90 ° or less, and it is formed from a pressure-sensitive adhesive composition that contains a copolymer obtained from a monomer mixture containing a specific amount of a specific monomer.
- the present inventors have found that the above-mentioned problems can be solved by using a pressure-sensitive adhesive layer.
- a pressure-sensitive adhesive layer for bonding a polarizing plate to an image display device, wherein the pressure-sensitive adhesive layer has a contact angle of 90 ° or less between the pressure-sensitive adhesive layer surface and water, and (A) a monomer mixture copolymer comprising the following monomers (a1) to (a5):
- a pressure-sensitive adhesive layer is provided, characterized in that it is obtained from a pressure-sensitive adhesive composition containing (B) 0.1 to 5 parts by mass of an isocyanate-based crosslinking agent with respect to 100 parts by mass of the copolymer (A).
- the pressure-sensitive adhesive layer is particularly effective when the polarizing plate has a polycycloolefin-based film as a protective film.
- This invention can also be a polarizing plate with an adhesive layer which has such an adhesive layer on the at least one surface of the said polarizing plate.
- the laminated body which bonded the polarizing plate with an adhesive layer further to the glass substrate is also provided.
- the glass substrate is particularly preferably a glass substrate used in an image display device.
- the present invention excellent durability is exhibited under high temperature conditions and high humidity conditions, and adhesion between a glass substrate and a polarizing plate whose protective film is a polycycloolefin-based film, and a polarizing plate and a retardation film It is possible to provide a pressure-sensitive adhesive layer having excellent adhesion to an optical film. Further, the pressure-sensitive adhesive layer can reduce light leakage of the image display device.
- FIG. 1 is a cross-sectional view schematically showing an example of a laminate according to an embodiment of the present invention.
- FIG. 2 is a cross-sectional view schematically showing an example of a laminate according to an embodiment of the present invention.
- parts means “parts by mass” and “%” means “mass%” unless otherwise specified.
- the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a copolymer (A) and an isocyanate-based crosslinking agent (B) described below as essential components.
- the agent layer is characterized in that the contact angle with water is 90 ° or less by a measurement method described later.
- the contact angle is an angle of a liquid contact portion generated when a liquid touches a solid surface.
- This contact angle is an important physical property that represents the wettability of a solid and a liquid when the surface tension (surface energy) of the solid and the liquid and the interfacial tension between the solid and the liquid are in a mechanical equilibrium state. And is defined by Young's equation (1).
- ⁇ s ⁇ l ⁇ cos ⁇ + ⁇ sl (1)
- ⁇ contact angle ⁇ s: surface tension of solid (surface energy)
- ⁇ l surface tension of liquid (surface energy)
- ⁇ sl Interfacial tension between solid and liquid
- the present inventor made contact with the polycycloolefin-based film by setting the contact angle ⁇ between the adhesive layer surface and water to 90 ° or less, more preferably 40 ° to 90 °. It has been found that a pressure-sensitive adhesive layer having excellent adhesion can be obtained. When the contact angle with water exceeds 90 °, the pressure-sensitive adhesive layer is inferior in adhesion to the polycycloolefin film.
- the hydrophilicity of the pressure-sensitive adhesive layer may be too high and the durability may deteriorate.
- the contact angle with water is 50 ° or more and 90 ° or less because the balance between adhesion and durability is particularly excellent.
- copolymer (A) (hereinafter sometimes simply referred to as “component (A)”) is a copolymer of a monomer mixture containing the monomers (a1) to (a4) as essential components. .
- the monomer (a1) is a polyoxyalkylene group- or alkoxyalkyl group-containing monomer.
- the monomer (a1) preferably has no crosslinkable group. Examples of the crosslinkable group include a hydroxyl group and a carboxyl group.
- the monomer (a1) is preferably a (meth) acrylic acid ester.
- the monomer (a1) is represented by, for example, the formula (a-1).
- CH 2 CR 1 -COOR 2 (a-1)
- R 1 is a hydrogen atom or a methyl group
- R 2 is a group represented by the formula (g-1).
- R 3 is an alkylene group
- R 4 is an alkyl group
- n is an integer of 1 or more.
- the carbon number of the alkylene group is usually 1 to 10, preferably 1 to 5.
- the alkyl group usually has 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms.
- n is preferably 1 to 20, more preferably 1 to 4, and still more preferably 1 to 2.
- Examples of the monomer (a1) include alkoxyalkyl (meth) acrylate and alkoxypolyalkylene glycol mono (meth) acrylate.
- Examples of the alkoxyalkyl (meth) acrylate include methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl ( And (meth) acrylate, 4-methoxybutyl (meth) acrylate, and 4-ethoxybutyl (meth) acrylate.
- alkoxypolyalkylene glycol mono (meth) acrylate examples include methoxydiethylene glycol mono (meth) acrylate, methoxydipropylene glycol mono (meth) acrylate, ethoxytriethylene glycol mono (meth) acrylate, ethoxydiethylene glycol mono (meth) acrylate, And methoxytriethylene glycol mono (meth) acrylate.
- the monomer (a1) an alkoxyalkyl (meth) acrylate in which R 2 in the formula (a-1) is an alkoxyalkyl group is preferable from the viewpoint of reactivity.
- a monomer (a1) may be used individually by 1 type, and may use 2 or more types.
- the pressure-sensitive adhesive layer can exert a birefringence adjusting function, so that the photoelastic coefficient can be optimized. Light leakage of the image display device can be prevented.
- the content of the monomer (a1) in the monomer mixture is 30 to 98.8% by mass, and 50 It is preferably ⁇ 98.8% by mass, and more preferably 50 to 98.3% by mass. In one embodiment, the content of the monomer (a1) in the monomer mixture may be 50 to 97.7% by mass.
- Monomer (a2) The hydroxyl group-containing monomer as the monomer (a2) can impart a crosslinking point with the isocyanate-based crosslinking agent (B) to the component (A).
- the content of the monomer (a2) in the monomer mixture is 0.1 to 10% by mass, preferably 0.1 to 5% by mass. More preferably, the content is 0.1 to 2% by mass.
- the monomer (a2) has a polymerizable double bond in addition to the hydroxyl group. However, a monomer having a carboxyl group is excluded from the monomer (a2).
- the monomer (a2) include hydroxyalkyl (meth) acrylate and alkylene glycol (meth) acrylate. Specific examples of the hydroxyalkyl (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. 8-hydroxyoctyl (meth) acrylate and 2-hydroxy-3-phenoxypropyl (meth) acrylate.
- alkylene glycol (meth) acrylate examples include polyethylene glycol (meth) acrylate, propylene glycol (meth) acrylate, and polypropylene glycol (meth) acrylate.
- a monomer (a2) may be used individually by 1 type, and may use 2 or more types.
- Monomer (a3) (A) component which has a carboxyl group is obtained by copolymerizing the monomer mixture containing the carboxyl group-containing monomer which is a monomer (a3).
- the carboxyl group of the component (A) forms a hydrogen bond in the pressure-sensitive adhesive composition, it is possible to impart cohesive force to the pressure-sensitive adhesive layer and improve the durability of the pressure-sensitive adhesive layer.
- the adhesive layer can improve the adhesive force with respect to a to-be-adhered body by using (A) component which has a carboxyl group.
- the content of the monomer (a3) in the monomer mixture is 0.1 to 10% by mass, and is 0.1 to 5% by mass. Is preferable, 0.1 to 2% by mass is more preferable, and 0.6 to 2% by mass is particularly preferable.
- the content of the monomer (a3) in the monomer mixture may be 1.2 to 2% by mass.
- the carboxyl group-containing monomer that is the monomer (a3) has a polymerizable double bond-containing group in addition to the carboxyl group.
- the monomer (a3) include (meth) acrylic acid, carboxyl group-containing (meth) acrylate, and a monomer having a carboxyl group and a polymerizable double bond without having a (meth) acryloyl group.
- the carboxyl group-containing (meth) acrylate include ⁇ -carboxyethyl (meth) acrylate and 5-carboxypentyl (meth) acrylate.
- a carboxyl group-containing monomer such as itaconic acid, maleic acid, fumaric acid, crotonic acid, or isocrotonic acid or its anhydride (Such as maleic anhydride).
- the monomer (a3) is preferably (meth) acrylic acid and a carboxyl group-containing (meth) acrylate.
- the (meth) acrylic acid alkyl ester monomer which is the monomer (a4) does not contain any of a polyoxyalkylene group, an alkoxyalkyl group and a crosslinkable group.
- the carbon number of the alkyl group of the (meth) acrylic acid alkyl ester monomer which is the monomer (a4) is usually 1 to 24.
- Examples of the monomer (a4) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth) acrylate.
- a monomer (a4) may be used individually by 1 type, and may use 2 or more types.
- the number of carbon atoms in the alkyl chain of the monomer (a4) is preferably 1 to 20, more preferably 1 to 10.
- the content of the monomer (a4) in the monomer mixture is 1 to 69.8% by mass, and 1 to 50% by mass. It is preferably 1 to 49.3 mass%.
- the monomer mixture may contain a copolymerizable monomer other than the above (a1) to (a4) which is the monomer (a5).
- the monomer (a5) include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, N, N— Dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, t- Amide group or amino group-containing (meth) acrylic monomers such as octyl (meth) acrylamide and diacetone (meth) acrylamide; other nitrogen-containing monomers
- Total amount of monomers (a1) to (a4) in the pressure-sensitive adhesive layer of the present invention excellent durability, high adhesion between the glass substrate and the polycycloolefin film, and between the polycycloolefin films
- the total amount of the monomers (a1), (a2), (a3) and (a4) in the monomer mixture is 70 to 100% by mass. It is preferably 80 to 100% by mass.
- the polymerization method of the component (A) is not particularly limited and can be polymerized by a known method such as solution polymerization, emulsion polymerization, suspension polymerization or the like. It is preferable to polymerize by solution polymerization from the viewpoint that the treatment process is relatively simple and can be carried out in a short time when the pressure-sensitive adhesive composition is used.
- At least one of an organic solvent, a monomer, and a polymerization initiator may be sequentially added to the reaction system.
- the organic solvent include aromatic hydrocarbons such as benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and aromatic naphtha; n Aliphatic or alicyclic hydrocarbons such as hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, turpentine oil; ethyl acetate, n-butyl acetate, Esters such as n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybut
- organic solvents in the polymerization of the component (A), it is preferable to use an organic solvent that does not easily cause chain transfer during the polymerization reaction, for example, an ester or a ketone. From the viewpoint of ease of reaction, use of ethyl acetate, methyl ethyl ketone, acetone or the like is preferable.
- organic peroxides examples include t-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, and di-i-propyl peroxydicarbonate.
- azo compound examples include 2,2′-azobis-i-butyronitrile, 2,2 ′. -Azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and the like. These polymerization initiators can be used alone or in admixture of two or more.
- polymerization initiators that do not cause a graft reaction during the polymerization reaction of component (A) are preferable, and azo compounds are particularly preferable.
- the amount of the polymerization initiator used is usually 0.01 to 2 parts by weight, preferably 0.1 to 1.0 part by weight, based on 100 parts by weight of the total monomer mixture.
- a chain transfer agent can be used as necessary within the range not impairing the object and effect of the present invention.
- chain transfer agents examples include cyanoacetic acid; alkyl esters having 1 to 8 carbon atoms of cyanoacetic acid; bromoacetic acid; alkyl esters having 1 to 8 carbon atoms of bromoacetic acid; anthracene, phenanthrene, fluorene, 9-phenyl Aromatic compounds such as fluorene; aromatic nitro compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene; benzoquinone, 2,3,5,6-tetramethyl Benzoquinone derivatives such as p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane 3-
- the polymerization temperature in the production of the component (A) is generally about 30 to 180 ° C., preferably 40 to 150 ° C., more preferably 50 to 90 ° C.
- the reaction time is generally 4 to 20 hours.
- Weight average molecular weight and dispersion index (A) The weight average molecular weight (Mw) of component is the adhesion between the glass substrate and the polycycloolefin film and the polycycloolefin system. From the viewpoint of enhancing the adhesion between films, preventing light leakage, and enhancing durability, the film thickness is preferably 400,000 to 2,000,000, more preferably 750,000 to 1,500,000. When the Mw of the component (A) is less than 400,000, durability may be inferior. On the other hand, when it exceeds 2 million, light leakage may not be sufficiently reduced.
- the dispersion index (PDI, Mw / Mn) of the component (A) is preferably 10 to 20, and preferably 11 to 15 from the viewpoint of obtaining a pressure-sensitive adhesive layer having excellent adhesion to the polycycloolefin-based film. It is more preferable.
- PDI of the component (A) is in the above range, a pressure-sensitive adhesive layer excellent in durability can be obtained with a small amount of low molecular weight component in the component (A).
- Mw and Mn of (A) component are calculated
- the glass transition temperature (Tg) of the component (A) is ⁇ 70 to 0 ° C. It is preferably -50 to -10 ° C.
- the Tg of the component (A) is a value calculated by the following formula (2) (FOX formula).
- Tg A represents the glass transition temperature (K) of the component (A)
- Tg a1 , Tg a2 , Tg a3 , Tg a4 , Tg a5 are the monomers (a1), (a2), (A3), (a4), (a5) shows the glass transition temperature (Tg (K)) of the homopolymer prepared from (a5), W a1 , W a2 , W a3 , W a4 , W a5 are respectively (A) (The weight fraction of all structural units derived from the monomers (a1), (a2), (a3), (a4), and (a5) contained in the components) is shown.
- the monomer (aX) contains two or more monomers (for example, (aX-1) and (aX-2)) (X is an integer of 1 to 5).
- the term relating to the monomer (aX) of the above formula (2) can be expressed as the following formula (3).
- Tg aX-1 and Tg aX - 2 represent the glass transition temperature (Tg (K)) of the homopolymer prepared from the monomers (aX-1) and (aX-2), respectively, and W aX-1 and W aX-2 are the weight fractions of the structural unit amounts derived from the monomers (aX-1) and (aX-2), respectively, contained in the component (A). Show.)
- Tg A is calculated as an absolute temperature (K) according to the above equation (2), it is converted to a Celsius temperature (° C.) as necessary.
- K absolute temperature
- Tg of homopolymers prepared from typical monomers is described, for example, in Polymer Handbook 4th Edition (Polymer Handbook Forth Edition, Wiley-Interscience, 2003).
- Isocyanate-based crosslinking agent (B) Isocyanate-based crosslinking agent (B) (hereinafter sometimes simply referred to as “component (B)”) is not particularly limited as long as it is a crosslinking agent capable of crosslinking with component (A) at room temperature or under heating.
- isocyanate monomers such as xylylene diisocyanate, tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, and divalent or higher divalents such as trimethylolpropane
- isocyanate compound or an isocyanurate obtained by addition reaction with an alcohol compound or the like is exemplified.
- urethane prepolymer type isocyanates obtained by addition reaction of isocyanate compounds with known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and the like can be mentioned.
- tolylene diisocyanate and derivatives thereof are preferably used as the component (B).
- the content of the component (B) in the pressure-sensitive adhesive composition is 0.1 to 5 parts by mass with respect to 100 parts by mass of the component (A) from the viewpoint of achieving a predetermined gel fraction (eg, 50 to 90%). It is preferably 0.2 to 1 part by mass.
- the pressure-sensitive adhesive composition according to this embodiment can further contain components other than the component (A) and the component (B) as necessary.
- the pressure-sensitive adhesive composition according to the present embodiment includes (C) a silane coupling agent (hereinafter sometimes simply referred to as “component (C)”), as long as the effects of the present invention are not impaired.
- component (D) an ionic compound (hereinafter sometimes simply referred to as “component (D)”)
- component (E) an organic solvent hereinafter sometimes simply referred to as “component (E)”
- oxidation An inhibitor, an ultraviolet absorber, a tackifier, a plasticizer, and the like may be blended.
- Component (C) is, for example, a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane, or methacryloxypropyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxy Silicon compounds having an epoxy structure such as propylmethyldimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxy Amino group-containing silicon compounds such as silane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; oligomer type silane coupling agent.
- a polymerizable unsaturated group-containing silicon compound such as
- the silane coupling agent which has a functional group which reacts with the functional group contained in (A) component is preferable at the point that it is hard to produce peeling in a high-humidity heat environment.
- the content of the component (C) in the pressure-sensitive adhesive composition is 0.1 to 5 parts by mass with respect to 100 parts by mass of the component (A) from the viewpoint of maintaining good adhesion to the adherend.
- the amount is preferably 0.2 to 1 part by mass.
- the adhesive composition which concerns on this embodiment may contain the ionic compound (D).
- the component (D) include an ionic compound that is composed of an anion and a cation and is liquid or solid at 25 ° C., specifically, an alkali metal salt, an ionic liquid (liquid at 25 ° C. Shape), surfactants and the like.
- the pressure-sensitive adhesive composition according to this embodiment contains the component (D)
- the oxygen atom of the polyoxyalkylene group or alkoxyalkyl group derived from the component (a1) constituting the component (A) is replaced with the component (D).
- alkali metal salt examples include compounds comprising an alkali metal cation such as lithium, sodium and potassium and an anion.
- the cation constituting the ionic liquid includes pyridinium cation, piperidinium cation, pyrrolidinium cation, cation having pyrroline skeleton, cation having pyrrole skeleton, imidazolium cation, tetrahydropyridinium cation, dihydropyridinium cation, pyrazo
- the anion constituting the ionic liquid include Cl ⁇ , Br ⁇ , I ⁇ , AlCl 4 ⁇ , and the like.
- ionic liquid it is comprised from these cations and anions, and a liquid ionic compound is mentioned at 25 degreeC.
- ionic liquids include 2-methyl-1-pyrroline tetrafluoroborate, 1-ethyl-2-phenylindole tetrafluoroborate, 1,2-dimethylindole tetrafluoroborate, and 1-ethyl.
- Carbazole tetrafluoroborate 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazole 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium perfluorobutanesulfonate, 1-ethyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, Til-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-3-methylimidazolium tris (tri
- any of nonionic surfactants, cationic surfactants, anionic surfactants and amphoteric surfactants can be used.
- nonionic surfactant examples include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyethylene alkyls such as polyoxyethylene octylphenyl ether and polyoxyethylene nonielphenyl ether Sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate and other sorbitan higher fatty acid esters; polyoxyethylene sorbitan monolaurate and other polyoxyethylene sorbitan higher fatty acid esters; polyoxyethylene monolaurate, polyoxyethylene Polyoxyethylene higher fatty acid esters such as monostearate; oleic acid monoglyceride, stearic acid monoglyceride, etc. Glycerin higher fatty acid esters; polyoxyethylene, polyoxypropylene, polyoxypropylene polyoxybutylene and the like; and their block copolymers.
- cationic surfactant examples include alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, benzalkonium chloride salt, and alkyldimethylammonium ethosulphate.
- anionic surfactant examples include sodium laurate, sodium oleate, N-acyl-N-methylglycine sodium salt, sodium carboxylate such as sodium polyoxyethylene lauryl ether carboxylate, sodium dodecylbenzenesulfonate, Dialkylsulfosuccinate esters, sulfonates such as sodium dimethyl-5-sulfoisophthalate, sulfate esters such as sodium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene nonylphenyl ether sulfate, polyoxyethylene lauryl Examples thereof include phosphoric acid ester salts such as sodium phosphate and polyoxyethylene nonylphenyl ether sodium phosphate.
- amphoteric surfactant examples include carboxybetaine surfactants, aminocarboxylates, imidazolinium petines, lecithins, and alkylamine oxides.
- a conductive polymer a conductive polymer, conductive carbon, ammonium chloride, aluminum chloride, copper chloride, iron chloride, ammonium sulfate, and the like can be used. Among these, it is preferable to use an alkali metal salt as the component (D).
- the content of the component (D) in the pressure-sensitive adhesive composition is 0.1 to 10 masses per 100 parts by mass of the component (A). Part, preferably 0.5 to 5 parts by weight.
- the pressure-sensitive adhesive composition according to this embodiment preferably contains the component (E) in order to adjust its coating property. Examples of the component (E) include the organic solvents described in the section “(7) Polymerization method”.
- the content of the component (E) in the composition can be 50 to 90 parts by mass, and preferably 60 to 90 parts by mass with respect to 100 parts by mass of the component (A).
- the adhesive composition which concerns on this embodiment is normally prepared by mixing the said (A) and (B) component and arbitrary components as needed simultaneously or in arbitrary orders. Moreover, when mixing (A) component and (B) component, when preparing (A) component by solution polymerization, (B) component is added to the solution containing (A) component after the completion of polymerization. In addition, when the component (A) is prepared by bulk polymerization, uniform mixing becomes difficult after the completion of the polymerization. Therefore, it is preferable to add and mix the component (B) during the polymerization.
- the adhesive layer of this invention is formed from the above-mentioned adhesive composition.
- the pressure-sensitive adhesive layer can be obtained by proceeding with the crosslinking reaction in the above-mentioned pressure-sensitive adhesive composition, specifically, by crosslinking the component (A) with the component (B).
- the conditions for forming the pressure-sensitive adhesive layer are, for example, as follows.
- the pressure-sensitive adhesive composition is coated on a support, and varies depending on the type of solvent, but is usually dried at 50 to 150 ° C., preferably 60 to 100 ° C., usually 1 to 10 minutes, preferably 2 to 7 minutes.
- the solvent is removed to form a coating film.
- the film thickness of the dried coating film is usually 5 to 75 ⁇ m, preferably 10 to 50 ⁇ m.
- the pressure-sensitive adhesive layer is preferably formed under the following conditions. After the pressure-sensitive adhesive composition is applied to a support and a release film is applied on the coating film formed under the above conditions, it is usually 3 days or more, preferably 7 to 10 days, usually 5 to 60 ° C., preferably 15 Curing is performed in an environment of ⁇ 40 ° C., usually 30 to 70% RH, preferably 40 to 70% RH. When crosslinking is performed under the aging conditions as described above, a crosslinked body (network polymer) can be efficiently formed.
- a known thickness such as a spin coating method, a knife coating method, a roll coating method, a bar coating method, a blade coating method, a die coating method, or a gravure coating method may be used.
- the method of applying and drying can be used.
- polyester films such as polyethylene terephthalate (PET); and plastic films such as polyolefin films such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.
- PET polyethylene terephthalate
- plastic films such as polyolefin films such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.
- the pressure-sensitive adhesive according to the present embodiment is capable of preventing light leakage and enhancing the durability and adhesion between the adherend and the polycycloolefin-based film.
- the gel fraction of the agent composition is preferably 50 to 90%, more preferably 60 to 80%.
- the gel fraction is, for example, the types and amounts of the components (a2) and (a3) in the monomer mixture used when preparing the pressure-sensitive adhesive composition, ( It can adjust with the kind and usage-amount of the crosslinking agent which is B) component.
- the gel fraction 0.1 g (dry weight (1)) of the crosslinked adhesive was collected in a sample bottle, and 30 cc of ethyl acetate was further added to the sample bottle and shaken for 24 hours. After that, the contents of the sample bottle were filtered with a 200 mesh stainless steel wire mesh, the residue on the wire mesh was dried at 100 ° C. for 2 hours, and the dry weight (dry weight (2)) was measured. 4).
- Gel fraction (%) (dry weight (2) / dry weight (1)) ⁇ 100 (4)
- Polarizing plate As the polarizing plate, one used for forming an image display device such as a liquid crystal display device is used. In this specification, “polarizing plate” is used to include “polarizing film”.
- polarizing plate a conventionally known polarizing plate can be used, and examples thereof include a polarizing plate having a polarizer and a protective film disposed on one side or both sides of the polarizer.
- Examples of the polarizer include a stretched film obtained by adding a polarizing component to a film made of a polyvinyl alcohol resin and stretching the film.
- Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, and a saponified product of an ethylene / vinyl acetate copolymer.
- Examples of the polarizing component include iodine or a dichroic dye.
- the protective film examples include films made of cellulose such as triacetylcellulose and acetylcellulose such as diacetylcellulose, polycarbonate films, polyethersulfone films, and polycycloolefin films.
- the protective film of a polarizer is a polycycloolefin type film, since shrinkage
- the thickness of the polarizing plate is usually 30 to 250 ⁇ m, preferably 50 to 200 ⁇ m.
- the polarizing plate may be laminated with a layer having other functions such as an antiglare layer, a retardation layer, and a viewing angle improving layer.
- the “polycycloolefin-based film” includes at least 50% of a skeleton derived from polycycloolefin in a structural unit.
- the polycycloolefin-based film may be a polycycloolefin copolymer.
- the polycycloolefin copolymer may be formed by, for example, ethylene and polycycloolefin (for example, tetracyclododecene) under a Ziegler catalyst. It can be obtained by copolymerization.
- a commercially available polycycloolefin film can be used as the polycycloolefin film.
- Examples of commercially available polycycloolefin-based films include ZEONOR films (manufactured by ZEON CORPORATION) and ARTON films (manufactured by JSR).
- the surface of the polarizing plate is preferably subjected to corona treatment.
- the untreated polycycloolefin-based film has a contact angle of around 100 °, but the contact angle decreases to 40-50 ° by corona treatment.
- a normal pressure-sensitive adhesive has a contact angle of around 110 °, and even if it is a polycycloolefin film subjected to corona treatment, adhesion between the pressure-sensitive adhesive and the polycycloolefin film is extremely difficult.
- the pressure-sensitive adhesive layer of the present invention has a contact angle of 90 ° or less and has extremely high adhesion to a corona-treated polycycloolefin film.
- the polarizing plate with an adhesive layer and a laminate The polarizing plate with an adhesive layer is a polarizing plate in which the adhesive layer is formed on at least one surface of the polarizing plate surface.
- the method for forming the pressure-sensitive adhesive layer on the surface of the polarizing plate is not particularly limited.
- the method for applying the pressure-sensitive adhesive composition directly to the surface of the polarizing plate using a bar coater and drying and aging, the pressure-sensitive adhesive layer of the present invention as the polarizing plate A method of transferring to the surface and aging is mentioned.
- a double-sided pressure-sensitive adhesive sheet having only the pressure-sensitive adhesive layer, the above-mentioned pressure-sensitive adhesive layer formed on both surfaces of the base material and the base material A double-sided pressure-sensitive adhesive sheet having a base material, a single-sided pressure-sensitive adhesive sheet having the above-mentioned pressure-sensitive adhesive layer formed on one surface of the base material, and a surface of the pressure-sensitive adhesive sheet that is not in contact with the base material were peeled off
- An adhesive sheet to which a cover film is attached is mentioned.
- a base material and a cover film it is the same as that of the material illustrated in the column of the said adhesive layer.
- the formation conditions and gel fraction of the pressure-sensitive adhesive layer are the same as the conditions described in the column of the pressure-sensitive adhesive layer.
- the thickness of the pressure-sensitive adhesive layer is usually 5 to 75 ⁇ m, preferably 10 to 50 ⁇ m, from the viewpoint of maintaining adhesive performance.
- the film thickness of the substrate and the cover film is not particularly limited, but is usually 10 to 125 ⁇ m, preferably 25 to 75 ⁇ m.
- a liquid crystal element is manufactured by providing the polarizing plate with the pressure-sensitive adhesive layer on the substrate surface of the liquid crystal cell.
- the liquid crystal cell has a structure in which a liquid crystal layer is sandwiched between two substrates.
- the polarizing plate has a polarizer and a protective film disposed on the polarizer, and the polarizer, the protective film, the pressure-sensitive adhesive layer of the present invention, and a glass substrate are provided.
- a laminated body laminated in this order can be manufactured.
- FIG. 1 is a cross-sectional view schematically showing an example (laminate 100) of a laminate according to an embodiment of the present invention.
- the laminate 100 includes a glass substrate 10, a polycycloolefin-based film 32, and an adhesive layer 20 provided between the glass substrate 10 and the polycycloolefin-based film 32.
- the laminate 100 includes a polarizing film 30, and the polarizing film 30 can include a polycycloolefin-based film 32.
- the laminate 100 includes a glass substrate 10, a pressure-sensitive adhesive layer 20 provided on the glass substrate 10, and a polarizing film 30 provided on the glass substrate 10 via the pressure-sensitive adhesive layer 20.
- the polarizing film 30 includes a polycycloolefin film 32, a polyvinyl alcohol film 34 provided on the polycycloolefin film 32, and a TAC film 36 provided on the polyvinyl alcohol film 34.
- the glass substrate 10 and the polycycloolefin film 32 are bonded via the pressure-sensitive adhesive layer 20.
- FIG. 2 is a cross-sectional view schematically showing another example (laminate 200) of the laminate according to one embodiment of the present invention.
- the laminate 200 includes a glass substrate 10, a polycycloolefin film (retardation film) 32, and a polarizing film 130, and includes the glass substrate 10, the polycycloolefin film 32, and The polarizing film 130 is laminated in this order.
- the polycycloolefin-based film 32 can be a retardation film.
- the polycycloolefin film 32 and the polarizing film 130 are bonded via the pressure-sensitive adhesive layer 20. Further, the glass substrate 10 and the polycycloolefin-based film 32 are bonded via the pressure-sensitive adhesive layer 22.
- the polarizing film 130 includes a layer (second polycycloolefin film) 38 that is a polycycloolefin film or TAC film, a polyvinyl alcohol film 34 provided on the layer 38, and a polyvinyl alcohol film 34. And a TAC film 36 provided.
- the polycycloolefin-based film (first polycycloolefin-based film) 32 and the layer (second polycycloolefin-based film) 38 are bonded via the pressure-sensitive adhesive layer 20.
- the adhesive layers 20 and 22 in FIGS. 1 and 2 are adherends (in the adhesive layer 20 in FIG. 1 and the adhesive layer 22 in FIG. 2, the adherend is the glass substrate 10 or the polycycloolefin-based film 32.
- the adherend is formed on the surface of the polycycloolefin-based film 32 or the layer 38).
- the pressure-sensitive adhesive composition is applied to the surface of a release film (separator) with good smoothness, the coating film is dried, and then the coating is performed.
- the transfer method which transfers a film
- the laminate according to the present embodiment is used in, for example, an image display device (particularly a liquid crystal display device). More specifically, the laminate according to the present embodiment can be used for an image display device for a touch panel, for example.
- the glass substrate included in the laminate according to the present embodiment is preferably a glass substrate for a liquid crystal display device.
- the glass substrate constituting the laminate according to the present embodiment can be a glass substrate used for an image display device.
- the image display device can be, for example, a TFT (thin film transistor) liquid crystal display device used for a liquid crystal television, a computer monitor, a mobile phone, a tablet, and the like.
- the pressure-sensitive adhesive layer for bonding the polarizing plate according to the present embodiment to the image display device is kept in good contact with the adherend by adjusting the contact angle of the pressure-sensitive adhesive layer to a predetermined range. And has an excellent durability effect.
- the monomer (a1) in the monomer mixture for forming the component (A) provides moderate anchoring properties and light leakage prevention effects to the pressure-sensitive adhesive layer. That is, the present invention includes the component (A) by the component (A) formed from the monomer mixture containing a specific amount of the polyoxyalkylene group or alkoxyalkyl group-containing monomer that is the monomer (a1).
- the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition can obtain a pressure-sensitive adhesive layer having an elastic modulus suitable for a polycycloolefin-based film, the adhesiveness with the polycycloolefin-based film can be improved. Furthermore, it is based on a novel and original idea that can achieve both the light leakage prevention effect and the durability by adjusting the blending of the monomers (a2) to (a4) within a predetermined range.
- ⁇ GPC measurement conditions About the acrylic polymer, the weight average molecular weight (Mw) and the dispersion index (PDI) were calculated
- Measuring device HLC-8120GPC (manufactured by Tosoh Corporation)
- GPC column configuration The following five columns (all manufactured by Tosoh Corporation) (I) TSK-GEL HXL-H (guard column) (Ii) TSK-GEL G7000HXL (Iii) TSK-GEL GMHXL (Iv) TSK-GEL GMHXL (V) TSK-GEL G2500HXL Diluted with tetrahydrofuran so that the sample concentration is 1.0 mg / cm 3
- Mobile phase solvent Tetrahydrofuran Flow rate: 1.0 cm 3 / min Column temperature: 40 ° C Standard polystyrene conversion
- the reaction was carried out for 8 hours while maintaining the temperature of the contents in the flask at 70 ° C. After 8 hours, 140 parts by mass of ethyl acetate was added to the reaction mixture to obtain a polymer solution 1 containing the acrylic polymer 1.
- the heating residue (nV%) at 105 ° C. of the obtained polymer solution 1 was 25.2%, and the viscosity at 23 ° C. was 5.2 Pa ⁇ s.
- Mw measured by GPC about the obtained acrylic polymer 1 was 902,000, and PDI was 12.
- the reaction was carried out for 3 hours while maintaining the temperature of the contents in the flask at 65 ° C. Thereafter, 160 parts by mass of ethyl acetate was added dropwise, and at the same time, the contents in the flask were heated to 75 ° C. and reacted for 5 hours. Eight hours after the start of the reaction, 120 parts by mass of ethyl acetate was added to the reaction mixture to obtain a polymer solution 6 containing an acrylic polymer 6. The obtained polymer solution 6 had a heating residue (nV%) of 20% and a viscosity at 23 ° C. of 3.8 Pa ⁇ s. Moreover, Mw measured by GPC about the obtained acrylic polymer 9 was 1.1 million, and PDI was 24.
- the unit of the numerical value of the monomer in Table 1 is part by mass.
- the abbreviation in Table 1 has the following meaning.
- BA butyl acrylate (Tg of homopolymer: ⁇ 50 ° C.)
- EHA 2-ethylhexyl acrylate (homopolymer Tg: -70 ° C)
- MEA 2-methoxyethyl acrylate (Tg of homopolymer: ⁇ 50 ° C.)
- AA Acrylic acid (Tg of homopolymer: 106 ° C.)
- HEA 2-hydroxyethyl acrylate (Tg of homopolymer: ⁇ 15 ° C.)
- Example 1 (1) Preparation of pressure-sensitive adhesive composition
- component (B) and (C) with respect to 100 parts by mass of the solid content of the polymer solution 1
- the ingredients were blended at the blending ratios in Table 2 below and mixed well.
- solid content means all the components remove
- Example 2 [Examples 2 to 9 and Comparative Examples 1 to 3]
- Example 1 the adhesive composition, the adhesive sheet, and the polarizing plate with an adhesive layer were obtained like Example 1 except having changed the compounding composition as described in Table 2.
- Photoelastic coefficient A pressure-sensitive adhesive layer prepared by peeling a PET film from the pressure-sensitive adhesive sheet for evaluation obtained in Examples and Comparative Examples and bonding the pressure-sensitive adhesive layers having a thickness of 25 ⁇ m to each other multiple times to adjust the thickness to 1 mm. Then, an automatic wavelength scanning ellipsometer (M220 type, manufactured by JASCO Corp.) was used for measurement under the condition of a measurement wavelength of 600 nm, and the obtained measurement value was used as a photoelastic coefficient.
- M220 type manufactured by JASCO Corp.
- the polarizing plate with the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples was cut into a size of 80 mm ⁇ 140 mm, and the polarization axis was on both sides of a non-alkali glass plate having a thickness of 1.1 mm.
- a test plate was prepared by sticking with a laminator roll so as to be orthogonal to each other, and then holding for 20 minutes in an autoclave adjusted to 50 ° C. and 5 atm. This test plate was allowed to stand for 500 hours at a temperature of 80 ° C., and light leakage was observed according to the following criteria. (Standard) AA: No light leakage was observed. BB: Slight light leakage was observed. CC: Light leakage was clearly observed.
- the unit of the numerical value of the pressure-sensitive adhesive composition in Table 2 is part by mass.
- the abbreviation in Table 2 has the following meaning.
- L-45 TDI curing agent (manufactured by Soken Chemical Co., Ltd.)
- KBM403 Silane coupling agent (manufactured by Shin-Etsu Silicone)
- the pressure-sensitive adhesive layer was formed from a pressure-sensitive adhesive composition containing the component (A) and the component (B), and the pressure-sensitive adhesive layer surface, water, And the component (A) is a copolymer of a monomer mixture containing the monomers (a1) to (a5) satisfying a predetermined condition, so that an adhesive is used. It can be understood that the adhesion between the glass substrate and the polyolefin-based film and the adhesion between the polycycloolefin-based films are excellent through the layers, high durability is achieved, and light leakage can be reduced.
- the pressure-sensitive adhesive layer has a monomer (a1) content of less than 30% by mass among the monomers constituting the component (A).
- the elastic modulus was not appropriate and light leakage occurred.
- the contact angle exceeded 90 degreeC, the adhesiveness to COP did not obtain a favorable result.
- the pressure-sensitive adhesive sheet of Comparative Example 2 did not contain the monomer (a2) in the monomer mixture constituting the component (A), the durability was inferior and the light leakage test could not be evaluated. Can understand.
- the pressure-sensitive adhesive sheet of Comparative Example 3 is inferior in durability because the amount of the monomers (a2) and (a3) in the monomer mixture constituting the component (A) is excessive. Understandable.
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Abstract
Description
(A)下記単量体(a1)~(a5)を含む単量体混合物の共重合体と、
(B)イソシアネート系架橋剤を前記共重合体(A)100質量部に対して0.1~5質量部と
を含む粘着剤組成物から得られることを特徴とする、粘着剤層が提供される。
(a1)ポリオキシアルキレン基またはアルコキシアルキル基含有単量体30~98.8質量%;
(a2)水酸基含有単量体0.1~10質量%;
(a3)カルボキシル基含有単量体0.1~10質量%;
(a4)(メタ)アクリル酸アルキルエステル単量体1~69.8質量%;
(a5)前記(a1)~(a4)以外の共重合性単量体0~30質量%;
ただし、前記単量体(a1)~(a5)を足し合わせて100質量%である。
前記粘着剤層は、前記偏光板が、保護フィルムとしてポリシクロオレフィン系フィルムを有する場合に特に有効である。
本発明はまた、このような粘着剤層を前記偏光板の少なくとも一方の面に有する粘着剤層付き偏光板であることもできる。
本発明によれば、粘着剤層付き偏光板をさらにガラス基板に貼り合わせた積層体も提供される。
前記ガラス基板は、特に画像表示装置に用いられるガラス基板であることが好ましい。
本実施形態に係る粘着剤層は、後述の共重合体(A)およびイソシアネート系架橋剤(B)を必須成分として含む粘着剤組成物から形成された粘着剤層であり、該粘着剤層は後述する測定方法によって水との接触角が90°以下であることを特徴とする。
一般に、接触角とは、固体表面上に液体が触れたときに生じる接液部分の角度である。この接触角は、固体および液体の表面張力(表面エネルギー)と、固体および液体の界面張力とが力学的な平衡状態にあるときに固体と液体との濡れ性を表す重要な物性で、濡れ現象の重要な尺度であり、Youngの式(1)により規定される。
γs=γl・cosθ+γsl ・・・(1)
θ :接触角
γs :固体の表面張力(表面エネルギー)
γl :液体の表面張力(表面エネルギー)
γsl:固体と液体の界面張力
本発明者は、粘着剤層表面と水との接触角θを90°以下、さらに好ましくは40°以上90°以下にすることにより、ポリシクロオレフィン系フィルムとの密着性に優れた粘着剤層が得られることを見出した。水との接触角が90°を超える場合、粘着剤層はポリシクロオレフィン系フィルムとの密着性に劣る。一方、40°未満の場合、粘着剤層の親水性が高すぎて耐久性が悪化することがある。なお、水との接触角が、50°以上90°以下であると、密着性と耐久性とのバランスが特に優れるのでより好ましい。
1.2.1.共重合体(A)
共重合体(A)(以下、単に「(A)成分」と記載することもある。)は、単量体(a1)~(a4)を必須とする単量体混合物の共重合体である。
単量体(a1)は、ポリオキシアルキレン基またはアルコキシアルキル基含有単量体である。単量体(a1)は架橋性基を有しないことが好ましい。架橋性基としては、例えば、水酸基、カルボキシル基が挙げられる。また、単量体(a1)は(メタ)アクリル酸エステルであることが望ましい。
単量体(a1)は、例えば、式(a-1)で表される。
CH2=CR1-COOR2・・・(a-1)
R1は水素原子またはメチル基であり、R2は、式(g-1)で表される基である。
-(R3O)nR4・・・(g-1)
R3はアルキレン基であり、R4はアルキル基であり、nは1以上の整数である。アルキレン基の炭素数は、通常1~10、好ましくは1~5である。アルキル基の炭素数は、通常1~10、好ましくは1~4である。nは、好ましくは1~20、より好ましくは1~4、さらに好ましくは1~2である。
単量体(a1)としては、これらの中でも、反応性の観点から、式(a-1)のR2がアルコキシアルキル基であるアルコキシアルキル(メタ)アクリレートが好ましい。
単量体(a1)は1種単独で用いてもよく、2種以上を用いてもよい。
単量体(a2)である水酸基含有単量体は、イソシアネート系架橋剤(B)との架橋点を(A)成分に付与することができる。粘着剤層の耐久性を確保するため、単量体混合物中の単量体(a2)の含有量は、0.1~10質量%であり、0.1~5質量%であることが好ましく、0.1~2質量%であることがより好ましい。
単量体(a2)としては、例えば、ヒドロキシアルキル(メタ)アクリレート、アルキレングリコール(メタ)アクリレートが挙げられる。具体的にはヒドロキシアルキル(メタ)アクリレートとして、例えば、2-ヒドロキシエチル(メタ)アクリレート、2-ヒドロキシプロピル(メタ)アクリレート、4-ヒドロシキブチル(メタ)アクリレート、6-ヒドロキシヘキシル(メタ)アクリレート、8-ヒドロキシオクチル(メタ)アクリレート、2-ヒドロキシ-3-フェノキシプロピル(メタ)アクリレートが挙げられる。アルキレングリコール(メタ)アクリレートとして、例えば、ポリエチレングリコール(メタ)アクリレート、プロピレングリコール(メタ)アクリレート、ポリプロピレングリコール(メタ)アクリレートが挙げられる。
単量体(a2)は1種単独で用いてもよく、2種以上を用いてもよい。
単量体(a3)であるカルボキシル基含有単量体を含む単量体混合物を共重合させることにより、カルボキシル基を有する(A)成分が得られる。(A)成分のカルボキシル基が粘着剤組成物内で水素結合を形成することにより、粘着剤層に凝集力を付与し、粘着剤層の耐久性を向上させることができる。また、カルボキシル基を有する(A)成分を用いることにより、粘着剤層は、被着体に対する粘着力を向上させることができる。高い耐久性を有する粘着剤層を得る観点から、単量体混合物中の単量体(a3)の含有量は、0.1~10質量%であり、0.1~5質量%であることが好ましく、0.1~2質量%であることがより好ましく、0.6~2質量%であることが特に好ましい。また、一実施形態として、単量体混合物中の単量体(a3)の含有量を、1.2~2質量%とすることもできる。
単量体(a3)としては、(メタ)アクリル酸、カルボキシル基含有(メタ)アクリレート、(メタ)アクリロイル基を有さずカルボキシル基および重合性二重結合を有する単量体等が挙げられる。カルボキシル基含有(メタ)アクリレートとしては、例えば、β-カルボキシエチル(メタ)アクリレート、5-カルボキシペンチル(メタ)アクリレートが挙げられる。(メタ)アクリロイル基を有さずカルボキシル基および重合性二重結合を有する単量体としては、イタコン酸、マレイン酸、フマル酸、クロトン酸、イソクロトン酸などのカルボキシル基含有単量体又はその無水物(無水マレイン酸など)が挙げられる。このうち、共重合性の観点から、単量体(a3)は、(メタ)アクリル酸およびカルボキシル基含有(メタ)アクリレートが好ましい。
単量体(a4)である(メタ)アクリル酸アルキルエステル単量体は、ポリオキシアルキレン基、アルコキシアルキル基および架橋性基のいずれも含まない。
単量体(a4)は1種単独で用いてもよく、2種以上を用いてもよい。
単量体混合物は、単量体(a5)である前記(a1)~(a4)以外の共重合性単量体を含んでいてもよい。単量体(a5)としては、例えば、N,N-ジメチルアミノエチル(メタ)アクリレート、N,N-ジエチルアミノエチル(メタ)アクリレート、N,N-ジメチルアミノプロピル(メタ)アクリルアミド、N,N-ジメチル(メタ)アクリルアミド、N,N-ジエチル(メタ)アクリルアミド、N,N-ジメチルアミノエチル(メタ)アクリルアミド、N,N-ジメチルアミノプロピル(メタ)アクリルアミド、N-イソプロピル(メタ)アクリルアミド、t-オクチル(メタ)アクリルアミド、ダイアセトン(メタ)アクリルアミド等のアミド基またはアミノ基含有(メタ)アクリル系単量体;アクリルアミド、ペンタメチルピペリジン(メタ)アクリレート、アクリロイルモルホリン等のその他の窒素含有単量体;ベンジル(メタ)アクリレート、2-ナフチル(メタ)アクリレート、フェノキシエチル(メタ)アクリレート等のエステル部位に芳香環基を有する(メタ)アクリル酸エステル単量体;シクロヘキシル(メタ)アクリレート、イソボルニル(メタ)アクリレート等の脂環基を有する(メタ)アクリル酸エステル単量体;グリシジル(メタ)アクリレート、テトラヒドロフルフリル(メタ)アクリレート等のエーテル環を有する(メタ)アクリレート;アクリロニトリル等のアクリロイル基を有する単量体;スチレン、α-メチルスチレン、o-メチルスチレン、p-メチルスチレン等のスチレン系モノマー;酢酸ビニル等のカルボン酸ビニルエステル;ビニルピリジン、N-ビニルピロリドン、ビニルカプロラクタム、ビニル(メタ)アクリロイル基含有マクロモノマーが挙げられる。
単量体(a5)は、1種単独で用いてもよく、2種以上を用いてもよい。単量体混合物中の単量体(a5)の含有量は、0~30質量%であり、0~20質量%であることが好ましい。
本発明の粘着剤層において、優れた耐久性、ならびにガラス基板とポリシクロオレフィン系フィルムとの高い密着性およびポリシクロオレフィン系フィルム同士の高い密着性を達成する観点から、前記単量体混合物中における前記単量体(a1)、(a2)、(a3)および(a4)の合計量は、70~100質量%であることができ、80~100質量%であることが好ましい。
(A)成分の重合方法は、特に制限されるものではなく、溶液重合、乳化重合、懸濁重合などの公知の方法により重合できるが、重合により得られた共重合体を用いて、粘着剤組成物を製造するにあたり、処理工程が比較的簡単でかつ短時間で行える観点から、溶液重合により重合することが好ましい。
これらの重合開始剤はそれぞれ単独で、又は2種以上混合して用いることができる。
(8-1)重量平均分子量および分散指数
(A)成分の重量平均分子量(Mw)は、ガラス基板とポリシクロオレフィン系フィルムとの密着性およびポリシクロオレフィン系フィルム同士の密着性を高め、光漏れを防止し、かつ耐久性を高めることができる観点から、40万~200万であることが好ましく、75万~150万であることがより好ましい。(A)成分のMwが40万未満であると、耐久性に劣ることがあり、一方、200万を超えると、光漏れを十分に低減することができないことがある。
ここで、(A)成分のMwおよびMnは、GPC(ゲルパーミエーションクロマトグラフィー)を用い、実施例に記載の条件で標準ポリスチレン換算により求めたものである。
光漏れを防止し、かつ耐久性および被着体とポリシクロオレフィン系フィルムとの密着性を高めることができる観点から、(A)成分のガラス転移温度(Tg)は-70~0℃であることが好ましく、-50~-10℃であることがより好ましい。なお、本発明において、(A)成分のTgは、下記式(2)(FOXの式)により算出された値である。
1/TgA=Wa1/Tga1+Wa2/Tga2+Wa3/Tga3+Wa4/Tga4+Wa5/Tga5 ・・・・(2)
(式中、TgAは、(A)成分のガラス転移温度(K)を示し、Tga1、Tga2、Tga3、Tga4、Tga5はそれぞれ、単量体(a1)、(a2)、(a3)、(a4)、(a5)から調製されたホモポリマーのガラス転移温度(Tg(K))を示し、Wa1、Wa2、Wa3、Wa4、Wa5はそれぞれ、(A)成分中に含まれる、単量体(a1)、(a2)、(a3)、(a4)、(a5)に由来する構造単位量の全構造単位中の重量分率を示す。)
なお、例えば、単量体(aX)中に、2種以上の単量体(例えば、(aX-1)および(aX-2))を含む場合(Xは1~5の整数である。)、上記式(2)の単量体(aX)に関する項は、下記式(3)のように書き表せる。
WaX/TgaX=WaX-1/TgaX-1+WaX-2/TgaX-2 ・・・・(3)
(式中、TgaX-1、TgaX―2はそれぞれ、単量体(aX-1)、(aX-2)から調製されたホモポリマーのガラス転移温度(Tg(K))を示し、WaX-1、WaX-2はそれぞれ、(A)成分中に含まれる、単量体(aX-1)、(aX-2)に由来する構造単位量の全構造単位中の重量分率を示す。)
イソシアネート系架橋剤(B)(以下、単に「(B)成分」と記載することもある。)は、常温又は加熱下で(A)成分と架橋し得る架橋剤であれば特に限定されないが、例えば、キシリレンジイソシアネート、トリレンジイソシアネート、クロルフェニレンジイソシアネート、ヘキサメチレンジイソシアネート、テトラメチレンジイソシアネート、イソホロンジイソシアネート、ジフェニルメタンジイソシアネート、水添されたジフェニルメタンジイソシアネートなどのイソシアネートモノマーや、それらをトリメチロールプロパンなどの2価以上のアルコール化合物等に付加反応させたイソシアネート化合物やイソシアヌレート化物等が例示される。
本実施形態に係る粘着剤組成物は、必要に応じて、(A)成分および(B)成分以外の成分をさらに含むことができる。例えば、本実施形態に係る粘着剤組成物には、本発明の効果を損なわない範囲で、(C)シランカップリング剤(以下、単に「(C)成分」と記載することもある。)、(D)イオン性化合物(以下、単に「(D)成分」と記載する場合もある。)、(E)有機溶媒(以下、単に「(E)成分」と記載する場合もある。)、酸化防止剤、紫外線吸収剤、粘着付与剤、可塑剤等が配合されていても良い。
本実施形態に係る粘着剤組成物が(C)成分を含むことにより、本実施形態に係る粘着剤組成物を用いて被着体の表面に粘着剤層を形成した場合、被着体と粘着剤との接着を良好に保つことができる。(C)成分は、例えば、ビニルトリメトキシシラン、ビニルトリエトキシシラン及びメタクリロキシプロピルトリメトキシシラン等の重合性不飽和基含有ケイ素化合物;3-グリシドキシプロピルトリメトキシシラン、3-グリシドキシプロピルメチルジメトキシシラン及び2-(3,4-エポキシシクロヘキシル)エチルトリメトキシシラン等のエポキシ構造を有するケイ素化合物;3-アミノプロピルトリメトキシシラン、N-(2-アミノエチル)3-アミノプロピルトリメトキシシラン及びN-(2-アミノエチル)-3-アミノプロピルメチルジメトキシシラン等のアミノ基含有ケイ素化合物;3-クロロプロピルトリメトキシシラン;オリゴマー型シランカップリング剤が挙げられる。中でも、(A)成分中に含まれる官能基と反応する官能基を有しているシランカップリング剤が高湿熱環境下でハガレを生じさせにくいという点で好ましい。(C)成分の粘着剤組成物中の含有量は、被着体との接着を良好に保つことができる観点から、(A)成分100質量部に対して0.1~5質量部であることができ、0.2~1質量部であることが好ましい。
また、本実施形態に係る粘着剤組成物は、イオン性化合物(D)を含んでいてもよい。
(D)成分としては、例えば、アニオンとカチオンとからなる、25℃で液体状、または固体状のイオン性化合物が挙げられ、具体的には、アルカリ金属塩、イオン性液体(25℃で液体状)、界面活性剤等が挙げられる。本実施形態に係る粘着剤組成物が(D)成分を含むことにより、(A)成分を構成する(a1)成分由来のポリオキシアルキレン基またはアルコキシアルキル基の酸素原子が、(D)成分を構成するカチオンに配位することにより、高い帯電防止性能を実現することができる。
このなかでも、(D)成分として、アルカリ金属塩を使用することが好ましい。
(E)有機溶媒
本実施形態に係る粘着剤組成物は、その塗布性を調製するため、(E)成分を含有することが好ましい。(E)成分としては、「(7)重合方法」の欄で説明した有機溶媒が挙げられる。(E)成分の組成物中の含有量は、(A)成分100質量部に対して、50~90質量部であることができ、60~90質量部であることが好ましい。
本実施形態に係る粘着剤組成物は、通常、前記(A)および(B)成分および必要に応じて任意成分を、同時にあるいは任意の順番で混合して調製される。また、(A)成分と(B)成分とを混合するにあたり、(A)成分を溶液重合により調製した場合は、重合完了後の(A)成分を含む溶液に(B)成分を添加してもよく、(A)成分を塊状重合により調製する場合は、重合完了後では均一混合が困難になるため、この重合の途中で(B)成分を添加して混合することが好ましい。
本発明の粘着剤層は、上述の粘着剤組成物から形成される。例えば、上述の粘着剤組成物中の架橋反応を進めることにより、具体的には(A)成分を(B)成分で架橋することにより、前記粘着剤層が得られる。粘着剤層の形成条件は、例えば以下のとおりである。前記粘着剤組成物を支持体上に塗布し、溶媒の種類によっても異なるが、通常50~150℃、好ましくは60~100℃で、通常1~10分間、好ましくは2~7分間乾燥して溶媒を除去し、塗膜を形成する。乾燥塗膜の膜厚は、通常5~75μm、好ましくは10~50μmである。
ゲル分率(%)=(乾燥重量(2)/乾燥重量(1))×100 ・・・(4)
偏光板としては、液晶表示装置等の画像表示装置の形成に用いられるものが使用される。なお、本明細書では、「偏光板」は「偏光フィルム」を包含する意味で用いる。
偏光板の厚さは、通常30~250μm、好ましくは50~200μmである。
粘着剤層付き偏光板は、前記粘着剤層が偏光板表面の少なくとも一方の面に形成された偏光板である。偏光板表面に粘着剤層を形成する方法に特に制限はなく、偏光板表面に直接バーコーター等を用いて粘着剤組成物を塗布し乾燥および熟成させる方法、本発明の粘着剤層を偏光板表面に転写し熟成させる方法が挙げられる。粘着剤層を偏光板表面に転写する場合には、粘着剤層の取りうる形態として、例えば粘着剤層のみを有する両面粘着シート、基材と基材の両面に形成された上記粘着剤層とを有する両面粘着シート、基材と基材の一方の面に形成された上記粘着剤層を有する片面粘着シート、およびそれら粘着シートの粘着剤層の基材と接していない面に剥離処理されたカバーフィルムが貼付された粘着シートが挙げられる。基材およびカバーフィルムとしては、前記粘着剤層の欄で例示した材料と同様である。粘着剤層の形成条件やゲル分率は、前記粘着剤層の欄に記載した条件と同様である。粘着剤層の膜厚は、粘着性能維持の観点から、通常5~75μm、好ましくは10~50μmである。基材およびカバーフィルムの膜厚は、特に限定されないが、通常10~125μm、好ましくは25~75μmである。
本発明の粘着剤層を用いて、上記偏光板が偏光子および前記偏光子上に配置された保護フィルムを有し、前記偏光子、前記保護フィルム、本発明の粘着剤層、およびガラス基板がこの順に積層されてなる積層体を製造することができる。
本実施形態に係る偏光板を画像表示装置に貼り合わせるための粘着剤層は、その粘着剤層の接触角を所定の範囲に調整することにより被着体との密着を良好に保ちつつ、耐久性に優れた効果を有する。(A)成分を形成するための単量体混合物中の単量体(a1)が、粘着剤層に適度な投錨性および光漏れ防止効果をもたらす。すなわち、本発明は、単量体(a1)であるポリオキシアルキレン基またはアルコキシアルキル基含有単量体を特定量含む単量体混合物から形成される(A)成分によって、(A)成分を含む粘着剤組成物から形成される粘着剤層はポリシクロオレフィン系フィルムに適した弾性率を有する粘着剤層を得ることができるため、ポリシクロオレフィン系フィルムとの密着性を高めることができる上、さらに単量体(a2)~(a4)の配合を所定の範囲にすることで光漏れ防止効果と耐久性を両立できる、新規でかつ独創的な発想に基づくものである。
<加熱残分>
精秤したブリキシャーレにポリマー溶液を1g程度入れ、合計重量を精秤した後、105℃で3時間加熱し、加熱残分(nV)を測定した。加熱残分は、JIS K 5407:1997に準じて測定した。
<粘度測定>
ポリマー溶液を、ワニス入りの500ml瓶を25℃の恒温水槽に浸し12時間静置後、B型粘度計の測定方法に従い、粘度を測定した。
<GPC測定条件>
アクリル系重合体について、ゲルパーミエーションクロマトグラフィー法(GPC法)により、下記条件で、重量平均分子量(Mw)および分散指数(PDI)を求めた。
測定装置:HLC-8120GPC(東ソー社製)
GPCカラム構成:以下の5連カラム(すべて東ソー社製)
(i)TSK-GEL HXL-H (ガードカラム)
(ii)TSK-GEL G7000HXL
(iii)TSK-GEL GMHXL
(iv)TSK-GEL GMHXL
(v)TSK-GEL G2500HXL
サンプル濃度:1.0mg/cm3となるように、テトラヒドロフランで希釈
移動相溶媒:テトラヒドロフラン
流量:1.0cm3/min
カラム温度:40℃
標準ポリスチレン換算
撹絆装置、窒素ガス導入管、温度計および還流冷却管を備えたフラスコに、ブチルアクリレート8質量部、アクリル酸2-メトキシエチル90質量部、アクリル酸1質量部、2-ヒドロキシエチルアクリレート1質量部、および酢酸エチル140質量部を仕込み、フラスコ内に窒素ガスを導入しながらフラスコの内容物を70℃に加熱した。次いで、窒素ガスで十分に置換されたフラスコ内に、2,2´-アゾビス-i-ブチロニトリル(AIBN)0.1質量部を撹絆下で添加した。フラスコ内の内容物の温度を70℃に維持しながら8時間反応させた。8時間経過後の反応混合物に酢酸エチル140質量部を添加して、アクリル系重合体1を含むポリマー溶液1を得た。得られたポリマー溶液1の105℃での加熱残分(nV%)は25.2%、23℃における粘度は5.2Pa・sであった。また、得られたアクリル系重合体1についてGPCにより測定されたMwは90.2万であり、PDIは12であった。
重合反応に用いた重合性単量体を表1に記載したとおりに変更したこと以外は合成例1と同様に行い、アクリル系重合体2~8または10~12を含む、ポリマー溶液を調製した。結果を表1に示す。
撹絆装置、窒素ガス導入管、温度計および還流冷却管を備えたフラスコに、ブチルアクリレート8質量部、アクリル酸2-メトキシエチル90質量部、アクリル酸1質量部、2-ヒドロキシエチルアクリレート1質量部、および酢酸エチル120質量部を仕込み、フラスコ内に窒素ガスを導入しながらフラスコの内容物を65℃に加熱した。次いで、窒素ガスで十分に置換されたフラスコ内に、AIBN0.05質量部を撹絆下で添加した。フラスコ内の内容物の温度を65℃に維持しながら3時間反応させた。その後、酢酸エチル160質量部を滴下すると同時に、フラスコ内の内容物が75℃になるまで加熱し、5時間反応させた。反応開始から8時間後、反応混合物に酢酸エチル120質量部を添加して、アクリル系重合体6を含むポリマー溶液6を得た。得られたポリマー溶液6の加熱残分(nV%)は20%、23℃における粘度は3.8Pa・sであった。また、得られたアクリル系重合体9についてGPCにより測定されたMwは110万であり、PDIは24であった。
なお、表1における略語は以下の意味である。
BA:ブチルアクリレート(ホモポリマーのTg:-50℃)
2EHA:2-エチルヘキシルアクリレート(ホモポリマーのTg:-70℃)
MEA:2-メトキシエチルアクリレート(ホモポリマーのTg:-50℃)
AA:アクリル酸(ホモポリマーのTg:106℃)
HEA:2-ヒドロキエチルアクリレート(ホモポリマーのTg:-15℃)
(1)粘着剤組成物の作成
前記合成例1で得られたアクリル系重合体1を含むポリマー溶液1に、前記ポリマー溶液1の固形分100質量部に対して(B)成分および(C)成分を下記表2の配合比率にて配合し、よく混合した。ここで、固形分とは、ポリマー溶液から有機溶媒を除いた全成分をいう。
上記(1)で得られた粘着剤組成物を、泡抜け後、剥離処理されたポリエチレンテレフタレートフィルム(PETフィルム)上に、ドクターブレードを用いて液温25℃で塗布し、90℃で3分間乾燥して、乾燥膜厚25μmの塗膜を形成した。塗膜の前記PETフィルムの貼付面とは反対面に、剥離処理されたPETフィルムをさらに貼り合わせ、23℃/50%RH環境下で7日間静置して熟成させて、2枚のPETフィルムに挟まれた厚さ25μmの粘着剤層を有する粘着シートを得た。
(1)で得られた粘着剤組成物を、泡抜け後、ドクターブレートを用いPETセパレーターに塗工し、90℃で3分間乾燥して厚さ25μmの粘着剤層を作製した。当該シートの塗膜面を、ポリシクロオレフィン系(COP)フィルムを一表面に有する偏光板のCOPフィルム面に貼り合わせ、室温23℃、湿度65%の条件下、1~7日間静置し粘着剤層付き偏光板を得た。
実施例1において、配合組成を表2に記載したとおりに変更したこと以外は実施例1と同様にして、粘着剤組成物、粘着シートおよび粘着剤層付き偏光板を得た。
(1)ゲル分率
実施例および比較例で得られた粘着シートから粘着剤層1gを採取し、酢酸エチル50mlに投入し、振盪機(型名shaker SA-300、ヤマト科学株式会社製)にかけた。ゲル分を200メッシュのステンレス網にてろ過し、乾燥させた。その後、ろ過後の試料の質量をろ過前の試料の質量で除した値をゲル分率として算出した。
実施例および比較例で得られた評価用粘着シートからPETフィルムを剥離して、厚さ25μmの粘着剤層同士を複数回貼り合わせて1mm厚に調整した粘着剤層を、自動波長走査型エリプソメータ(M220型、日本分光社製)で、測定波長600nmの条件で測定し、得られた測定値を光弾性係数とした。
実施例および比較例で得られた粘着剤層付き偏光板を50mm×50mmの大きさに裁断し、PETセパレーターをはがした。シリンジに充填したイオン交換水を流量1μL、流速0.5μL/sで粘着剤層表面に滴下し、接触角計(dataphysics社製OCA15EC)により粘着剤層の接触角を測定した。
実施例および比較例で得られた粘着剤層付き偏光板を150mm×250mmの大きさに裁断し、試験片を作成した。試験片からPETセパレーターをはがし、ガラス板の片面にラミネーターロールを用いて貼着し、次いで、50℃にて5気圧に調整されたオートクレーブに20分間保持して試験板を作成した。同様の試験板を2枚作成した。一方の試験板は、耐熱試験のため、80℃の条件下で500時間放置した。もう一方の試験板は、耐湿試験のため、60℃でかつ湿度95%RHの条件下に500時間放置した。それぞれ、以下の基準でガラス板-粘着剤層の界面のハガレ、発泡の発生等を目視で確認した。
(基準)
AA:ハガレ等の外観不良は観察されなかった。
BB:ハガレ等の外観不良が僅かに観察された。
CC:ハガレ等の外観不良が明らかに観察された。
実施例および比較例で得られた粘着剤層付き偏光板を、80mm×140mmの大きさに裁断し、厚さ1.1mmの無アルカリガラス板の両側に、偏光軸が互いに直交するようにラミネーターロールを用いて貼着し、次いで50℃、5気圧に調整されたオートクレーブに20分間保持して試験板を作成した。この試験板を温度80℃の条件下に500時間放置し、以下の基準で光漏れの観察を行った。
(基準)
AA:光漏れは観察されなかった。
BB:光漏れが僅かに観察された。
CC:光漏れが明らかに観察された。
上記耐湿試験後の試験板について、偏光板のCOPフィルム面および粘着剤層の界面の密着を目視で確認して、以下の基準で評価した。
(基準)
AA:ハガレ等の外観不良は観察されなかった。
BB:ハガレ等の外観不良が僅かに観察された。
CC:ハガレ等の外観不良が部分的に観察された。
DD:ハガレ等の外観不良が顕著に観察された。
20,22 粘着剤層
30,130 偏光フィルム
32 位相差フィルム(ポリシクロオレフィン系フィルム)
34 ポリビニルアルコール(PVA)フィルム
36 TACフィルム
38 ポリシクロオレフィン系フィルムまたはTACフィルム
100,200 積層体
Claims (5)
- 偏光板を画像表示装置に貼り合わせるための粘着剤層であって、該粘着剤層は、粘着剤層表面と水との接触角が90°以下であり、かつ
(A)下記単量体(a1)~(a5)を含む単量体混合物の共重合体と、
(B)イソシアネート系架橋剤を前記共重合体(A)100質量部に対して0.1~5質量部と
を含む粘着剤組成物から得られることを特徴とする、粘着剤層:
(a1)ポリオキシアルキレン基またはアルコキシアルキル基含有単量体30~98.8質量%;
(a2)水酸基含有単量体0.1~10質量%;
(a3)カルボキシル基含有単量体0.1~10質量%;
(a4)(メタ)アクリル酸アルキルエステル単量体1~69.8質量%;
(a5)前記(a1)~(a4)以外の共重合性単量体0~30質量%;
ただし、前記単量体(a1)~(a5)を足し合わせて100質量%である。 - 偏光板が、保護フィルムとしてポリシクロオレフィン系フィルムを有する請求項1に記載の粘着剤層。
- 偏光板の少なくとも一方の面に、請求項1または2に記載の粘着剤層を有する粘着剤層付き偏光板。
- 請求項3に記載の粘着剤層付き偏光板を、ガラス基板に貼り合わせた積層体。
- 前記ガラス基板は、画像表示装置に用いられるガラス基板である、請求項4に記載の積層体。
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JP2022024067A (ja) * | 2017-06-22 | 2022-02-08 | 株式会社寺岡製作所 | アクリル樹脂組成物、粘着剤組成物、粘着シート用基材及び粘着シート |
US11958967B2 (en) | 2017-06-22 | 2024-04-16 | Teraoka Seisakusho Co., Ltd. | Acrylic resin composition, adhesive agent composition, base for adhesive sheet, and adhesive sheet |
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