WO2015141340A1 - 偏光板保護フィルム、その製造方法、偏光板及び液晶表示装置 - Google Patents
偏光板保護フィルム、その製造方法、偏光板及び液晶表示装置 Download PDFInfo
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- WO2015141340A1 WO2015141340A1 PCT/JP2015/053907 JP2015053907W WO2015141340A1 WO 2015141340 A1 WO2015141340 A1 WO 2015141340A1 JP 2015053907 W JP2015053907 W JP 2015053907W WO 2015141340 A1 WO2015141340 A1 WO 2015141340A1
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- protective film
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
- B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/04—Interconnection of layers
- B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L25/00—Compositions of, 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 an aromatic carbocyclic ring; Compositions of derivatives of such polymers
- C08L25/02—Homopolymers or copolymers of hydrocarbons
- C08L25/04—Homopolymers or copolymers of styrene
- C08L25/08—Copolymers of styrene
- C08L25/12—Copolymers of styrene with unsaturated nitriles
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/30—Properties of the layers or laminate having particular thermal properties
- B32B2307/306—Resistant to heat
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/40—Properties of the layers or laminate having particular optical properties
- B32B2307/42—Polarizing, birefringent, filtering
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/726—Permeability to liquids, absorption
- B32B2307/7265—Non-permeable
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2457/00—Electrical equipment
- B32B2457/20—Displays, e.g. liquid crystal displays, plasma displays
- B32B2457/202—LCD, i.e. liquid crystal displays
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2329/00—Characterised by the use of 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 an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
- C08J2329/02—Homopolymers or copolymers of unsaturated alcohols
- C08J2329/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
Definitions
- the present invention relates to a polarizing plate protective film, a manufacturing method thereof, a polarizing plate and a liquid crystal display device. More specifically, polarized light that has high water resistance, suppresses the occurrence of bend unevenness in a liquid crystal display device, and has good adhesion to a polarizer in combination with either water glue or an active energy ray-curable adhesive. It is related with a board protective film, its manufacturing method, a polarizing plate, and a liquid crystal display device.
- a polarizing plate provided in a liquid crystal display device generally has a polarizer and a pair of polarizing plate protective films sandwiching the polarizer.
- the polarizing plate protective film is highly transparent and can be saponified with an alkaline aqueous solution and used with a polyvinyl alcohol-based adhesive (also referred to as a water glue in the present application), thereby providing good adhesiveness with a polarizer. Since it is easy, the cellulose-ester film has been used conventionally.
- the cellulose ester film easily develops a desired retardation by an additive or stretching treatment, and is also used as a retardation film disposed on the liquid crystal cell side.
- the cellulose ester film has high moisture permeability. For example, when the film thickness is reduced, the amount of moisture permeation increases.
- liquid crystal display panel (a polarizing plate / liquid crystal cell / laminate of polarizing plates) including a thin glass substrate.
- a thin glass substrate When a thin glass substrate is used, There has been a problem that the glass substrate tends to bend (bend) due to heat from the backlight.
- the polarizing plate protective film and the polarizer constituting the polarizing plate are easily shrunk due to the moisture contained in the backlight due to the heat of the backlight. It was found that the liquid crystal display panel including the glass substrate is bent (bend), and as a result, display unevenness (bend unevenness) occurs in the liquid crystal display device.
- the polarizing plate protective film on the viewing side or the backlight side is required to have high water resistance in order to suppress the change of environment such as temperature and humidity and the evaporation of moisture due to the influence of the heat of the backlight.
- a polarizing plate protective film having high water resistance it is known to use an acrylic resin film, for example, an optical film using a polymethyl methacrylate film, as the polarizing plate protective film (for example, see Patent Document 1).
- the acrylic resin film is excellent in water resistance, it is inferior in adhesiveness with a polarizer which is a polyvinyl alcohol resin as compared with a cellulose ester film, and an easy-adhesion layer or the like is used from the viewpoint of improving adhesiveness.
- a polarizer which is a polyvinyl alcohol resin as compared with a cellulose ester film, and an easy-adhesion layer or the like is used from the viewpoint of improving adhesiveness.
- an adhesive a technique using an active energy ray-curable adhesive other than the above water paste is disclosed (for example, see Patent Documents 2 to 4), and the adhesive is an acrylic resin film and a polarizer. It is said that it is useful for pasting. However, a polarizing plate in which the acrylic resin film is bonded to a polarizer using an active energy ray curable adhesive is still not sufficient as an adhesive force, and film peeling or the like is likely to occur.
- JP 2012-180422 A JP 2010-230806 A JP 2010-077199 A JP 2011-123169 A
- the present invention has been made in view of the above-described problems and situations, and the solution is to suppress the occurrence of display unevenness (bend unevenness) in a liquid crystal display device, and to use water paste and active energy. It is to provide a polarizing plate protective film having good adhesion to a polarizer in any combination with a line curable adhesive, a method for producing the same, a polarizing plate provided with the polarizing plate protective film, and a liquid crystal display device. .
- the present inventor has obtained a copolymer obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer as a main component of a thermoplastic resin in the course of examining the cause of the above-mentioned problem. And a copolymer having an imide ring structure at a specific ratio, the polarizing plate protective film has high water resistance and heat resistance, and is either water glue or an active energy ray-curable adhesive. The present inventors have found that a polarizing plate protective film excellent in adhesiveness to a polarizer can be obtained even in combination.
- the polarizing plate protective film characterized by containing.
- the copolymer (A) obtained by polymerizing the aromatic vinyl monomer and the unsaturated nitrile monomer contains an aromatic vinyl monomer unit in the range of 50 to 75 mol% and an unsaturated nitrile monomer unit in the range of 25 to 50 mol.
- At least one of acid, alcohol, metal salt, nonionic surfactant or nonreactive quaternary ammonium salt type surfactant having a linear or branched alkyl group having 8 to 22 carbon atoms Any one of the first to fourth items, wherein the copolymer (A) and (B) are contained within a range of 0.1 to 1.0% by mass relative to the total mass of the copolymer (A) and (B) The polarizing plate protective film of description.
- Protective film
- the unreacted monomer of the aromatic vinyl monomer and unsaturated nitrile monomer contained in the copolymer (A) is 0.1% by mass or less based on the total mass of the copolymer (A).
- the polyvinyl alcohol-based polarizer can be bonded using any of a polyvinyl alcohol-based adhesive and an active energy ray-curable adhesive, according to any one of the first to eighth items.
- Polarizing plate protective film
- the said polarizing plate protective film is manufactured by the solution casting method, It is characterized by the above-mentioned.
- a method for producing a polarizing plate protective film is a manufacturing method of the polarizing plate protective film which manufactures the polarizing plate protective film as described in any one of Claim 1 to 9, Comprising: The said polarizing plate protective film is manufactured by the solution casting method, It is characterized by the above-mentioned. A method for producing a polarizing plate protective film.
- a polarizing plate wherein the polarizing plate protective film according to any one of items 1 to 9 and a polarizer are bonded using a polyvinyl alcohol-based adhesive.
- a polarizing plate wherein the polarizing plate protective film according to any one of items 1 to 9 and a polarizer are bonded using an active energy ray-curable adhesive.
- Item 14 The polarizing plate according to any one of items 11 to 13, wherein the adhesive on both sides of the polarizer is the same type of adhesive.
- a liquid crystal display device comprising: the polarizing plate protective film according to any one of items 1 to 9 disposed on a viewing side of a viewing side polarizing plate and a backlight side of a backlight side polarizing plate. .
- the present invention has high water resistance and heat resistance, suppresses occurrence of display unevenness (bend unevenness) of a liquid crystal display device, and can be polarized in combination with either water glue or an active energy ray-curable adhesive.
- the polarizing plate protective film which has favorable adhesiveness with a child, its manufacturing method, the polarizing plate provided with the said polarizing plate protective film, and a liquid crystal display device can be provided.
- the reason why the polarizing plate protective film of the present invention exhibits excellent adhesiveness with a polyvinyl alcohol polarizer with either a polyvinyl alcohol adhesive or an active energy ray curable adhesive is the copolymer according to the present invention (
- the imide ring constituting the acrylonitrile monomer constituting the A) and the copolymer (B) has a CN group and thus has a high polarity. Therefore, it is presumed that the adhesiveness is good due to the interaction with the water paste having the hydrophilic group. Is done.
- the copolymer (A) has an aromatic vinyl monomer such as styrene
- the tertiary carbon generates radicals by corona treatment or plasma treatment, and thus has good adhesion to an active energy ray-curable adhesive. It is inferred that
- the display unevenness (bend unevenness) of the liquid crystal display device since the aromatic vinyl monomer such as styrene constituting the copolymer (A) is hydrophobic, the water resistance is improved, and the film is caused by the loss of moisture from the film. Therefore, it is assumed that the panel is less likely to warp and the display unevenness (bend unevenness) is improved.
- the schematic diagram which shows an example of the solution casting film forming process flow applicable to manufacture of the polarizing plate protective film of this invention The schematic diagram which shows an example of a structure of the polarizing plate of this invention Sectional drawing which shows an example of a structure of the liquid crystal display device of this invention
- the copolymer (A) obtained by polymerizing the aromatic vinyl monomer and the unsaturated nitrile monomer contains 50 to 50 aromatic vinyl monomer units. It is highly water-resistant to contain an unsaturated nitrile monomer unit in a ratio of 75 mol% and 25 to 50 mol%, and it can be used as a water glue or an active energy ray-curable adhesive. Even if it uses, it is preferable from a viewpoint of providing the favorable adhesiveness with a polarizer.
- the aromatic vinyl monomer is styrene and the unsaturated nitrile monomer is acrylonitrile because compatibility with a compound having an imide ring structure is obtained in addition to the effects of the present invention.
- the Tg of the copolymer is increased to further improve the heat resistance, suppress panel deflection due to heat, and display unevenness (bend unevenness). Further improvements can be made.
- the dope is easily peeled off from the metal support, and the linear or branched alkyl having 8 to 22 carbon atoms is used to suppress the increase in haze and the occurrence of horizontal steps.
- At least one kind of group-containing acid, alcohol, metal salt, nonionic surfactant, or nonreactive quaternary ammonium salt type surfactant is used with respect to the total mass of the copolymers (A) and (B). It is preferably contained within the range of 0.1 to 1.0% by mass.
- the aromatic vinyl monomer and the unreacted monomer of an unsaturated nitrile monomer which the said copolymer (A) contains are 0.1 mass% or less with respect to the total mass of the said copolymer (A), respectively.
- the polarizing plate protective film of the present invention preferably has a haze of 1.0% or less and a yellow index (YI) of 1.0 or less as an optical film application requiring transparency. .
- the polarizing plate protective film of the present invention can be bonded to a polyvinyl alcohol polarizer by using either a polyvinyl alcohol-based adhesive or an active energy ray-curable adhesive. From the viewpoint of improving productivity and productivity.
- the method for producing a polarizing plate protective film of the present invention is preferably produced by a solution casting method, which reduces haze and yellow index (YI), and can provide excellent physical properties and optical properties as optical film applications. It is.
- the polarizing plate protective film of the present invention and the polarizing plate protective film on the opposite side across the polarizer are cellulose ester films, and the polarizing plate has excellent optical properties such as handleability, reworkability and visibility. Since it can provide, it is a preferable aspect.
- the adhesives on both sides of the polarizer are the same type of adhesive, which simplifies the bonding process and is advantageous in terms of cost.
- the polarizing plate protective film of the present invention can be disposed on the viewing side of the viewing side polarizing plate of the liquid crystal display device and the backlight side of the backlight side polarizing plate, due to high water resistance and heat resistance. This is a preferable arrangement from the viewpoint of suppressing bend unevenness.
- ⁇ is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
- the polarizing plate protective film which suppresses generation
- the polarizing plate protective film of the present invention contains the copolymer (A) and the copolymer (B) as main components of a thermoplastic resin used in the film.
- the “main component” as used herein means that 60% by mass or more of the thermoplastic resin constituting the polarizing plate protective film is the total amount of the copolymer (A) and the copolymer (B). Preferably it is 80 mass% or more, More preferably, it is 90 mass% or more, Most preferably, it is 95 mass% or more.
- the method for producing a polarizing plate protective film of the present invention is preferably produced by a solution casting method because haze and coloring (yellow index; YI) can be reduced.
- the polarizing plate protective film of the present invention is disposed on the viewing side of the viewing side polarizing plate of the liquid crystal display device and on the backlight side of the backlight side polarizing plate, thereby imparting high water resistance and heat resistance to the polarizing plate. This is preferable from the viewpoint of suppressing the occurrence of bend unevenness in the apparatus.
- the polarizing plate of the present invention has a configuration in which the polarizer is sandwiched between the polarizing plate protective film of the present invention and the cellulose ester phase difference film, thereby suppressing bend unevenness and excellent visibility. This is a preferred embodiment.
- the polarizing plate protective film of the present invention has good adhesiveness with a polarizer in combination with either water paste or an active energy ray curable adhesive, in the manufacturing process of a polarizing plate, water paste or active energy is used. What is necessary is just to prepare any one adhesive and the bonding apparatus of a line hardening type adhesive agent, and a bonding process does not become complicated and is advantageous also on cost.
- the monomer constituting the copolymer is referred to as “ ⁇ unit”.
- the aromatic vinyl monomer has a function of increasing the water resistance of the copolymer (A).
- the aromatic vinyl monomer is preferably a styrene compound.
- the styrenic compound examples include styrene; alkyl-substituted styrenes such as ⁇ -methylstyrene, ⁇ -methylstyrene, and p-methylstyrene; halogen-substituted styrenes such as 4-chlorostyrene and 4-bromostyrene; p- Hydroxystyrenes such as hydroxystyrene, ⁇ -methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3,4-dihydroxystyrene; vinylbenzyl alcohols; p-methoxystyrene, p-tert-butoxystyrene, alkoxy-substituted styrenes such as m-tert-butoxystyrene; vinyl benzoic acids such as 3-vinylbenzoic acid and 4-vinylbenzoic acid; 4-vinylbenzyl acetate
- styrene and ⁇ -methylstyrene are preferable, and styrene is particularly preferable because it is compatible with other styrene resins and (meth) acrylic resins.
- aromatic vinyl monomers may be used alone or in combination of two or more.
- Specific examples of the unsaturated nitrile monomer include vinyl cyanide compounds such as acrylonitrile, methacrylonitrile, ethacrylonitrile, fumaronitrile, and among them, acrylonitrile is preferable.
- the acrylonitrile monomer has a CN group and thus has high polarity, and has good adhesion due to interaction with water paste having a hydrophilic group.
- the unsaturated nitrile monomer may be used alone or in combination of two or more.
- the copolymer (A) according to the present invention may contain other monomers copolymerizable with the component (a) and / or the component (b).
- Examples of such copolymerizable monomer (c) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethyl (meth) acrylate, and 2-ethylhexyl methacrylate.
- Alkyl (meth) acrylates such as acrylates; (meth) acrylic acids such as acrylic acid and methacrylic acid; ⁇ , ⁇ -unsaturated carboxylic acids such as maleic anhydride; N-phenylmaleimide, N-methylmaleimide, N-cyclohexylmaleimide And glycidyl group-containing monomers such as glycidyl methacrylate.
- alkyl (meth) acrylates such as methyl acrylate are preferable.
- the other monomer (c) may be used alone or in combination of two or more.
- the copolymer (A) according to the present invention may be copolymerized at a ratio of the aromatic vinyl monomer unit in the range of 50 to 75 mol% and the unsaturated nitrile monomer unit in the range of 25 to 50 mol%. It is preferable in terms of compatibility with the copolymer (B) having an imide ring structure by balancing the water resistance and the adhesiveness of water paste. When other monomer units are used, it is preferable that they are copolymerized at a ratio in the range of 0 to 25% by mass.
- aromatic vinyl monomer units are used in the range of 65 to 75 mol%, unsaturated nitrile monomer units in the range of 25 to 35 mol%, and other monomer units in the range of 0 to 25 mol%. That is.
- the aromatic vinyl monomer unit is in the range of 50 to 75 mol%, the polarizing plate protective film can be imparted with high water resistance, and if the unsaturated nitrile monomer unit is in the range of 25 to 50 mol%, the hydrophilic property is obtained. Excellent adhesion to water paste having a base.
- emulsion polymerization method for example, in the production of styrene-acrylonitrile copolymer, emulsion polymerization method, suspension polymerization method and bulk polymerization method are generally used.
- a method for narrowing the composition distribution a complete mixing type in bulk polymerization is used. Examples include the production method used by the reactor.
- polymerization initiator a normal peroxide type or azo type can be used, and a redox type can also be used.
- suspension or emulsion polymerization can be carried out in a temperature range of 30 to 100 ° C.
- bulk or solution polymerization can be carried out in a temperature range of 80 to 160 ° C.
- polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.
- the polymerization is carried out using a fully mixed reactor in a full liquid state without the presence of a gas layer part, and the unreacted monomer after polymerization is preferably removed quickly.
- the removal of the unreacted monomer can be performed with a single-stage or multi-stage decompression device.
- the unreacted monomer of the aromatic vinyl monomer and unsaturated nitrile monomer which the said copolymer (A) contains is 0.1 mass% or less with respect to the total mass of the said copolymer (A), respectively. It is preferable from the viewpoint of preventing a decrease in the viscosity of the dope and preventing a deterioration in the toughness of the film.
- the value of the unreacted monomer ratio varies depending on the composition ratio of the copolymer (A).
- the unreacted unsaturated nitrile monomer unit is preferably in the range of 0.001 to 0.005%, If the aromatic vinyl monomer unit is in the range of 0.05 to 0.1%, the above effect can be exhibited, which is preferable.
- the unreacted monomer content can be controlled by controlling the polymerization temperature and polymerization time in the polymerization reactor, the heating temperature in the heater, the melting temperature in the devolatilizing extruder, and the unreacted monomer from the vent of the devolatilizing extruder. It can be adjusted by the displacement of volatile components. In order to reduce the content of the unreacted monomer, for example, it is preferable to lengthen the polymerization time in the polymerization reactor or increase the exhaust amount of volatile components from the vent of the devolatilizing extruder.
- the content of unreacted monomer is the polymerization temperature and polymerization time in the polymerization reactor, the heating temperature in the heater, the melting temperature in the devolatilizing extruder, and the vent of the devolatilizing extruder (including the unreacted monomer). It can be adjusted by the displacement of volatile components. In order to reduce the content of the unreacted monomer, for example, the polymerization time in the polymerization reactor may be increased, or the exhaust amount of the volatile component from the vent of the devolatilizing extruder may be increased.
- Unreacted monomer can be measured by the following method.
- the content of the unreacted monomer contained in the copolymer according to the present invention can be measured by the following method.
- the content (% by mass) of the unreacted monomer with respect to the total mass of the copolymer contained in the sample solution is measured by GC / MS.
- the measuring apparatus and measuring conditions of GC / MS are as follows.
- the weight average molecular weight (Mw) of the copolymer according to the present invention is preferably in the range of 1,000 to 2,000,000, more preferably in the range of 5,000 to 1,000,000, and more preferably 1 in terms of styrene conversion molecular weight. It is in the range of 10,000 to 500,000, particularly preferably in the range of 50,000 to 500,000.
- the weight average molecular weight is measured using a gel permeation chromatography (HLC8220GPC manufactured by Tosoh Corporation) and a column (TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL in series) manufactured by Tosoh Corporation.
- HSC8220GPC gel permeation chromatography
- TSK-GEL G6000HXL-G5000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL in series manufactured by Tosoh Corporation.
- a sample 20 mg ⁇ 0.5 mg was dissolved in 10 ml of tetrahydrofuran and filtered through a 0.45 mm filter. 100 ml of this solution is injected at a column temperature of 40 ° C., measured at a detector RI temperature of 40 ° C., and converted into styrene.
- the polarizing plate protective film of this invention contains the copolymer (B) which has an imide ring structure in a structure from a viewpoint of the heat resistance improvement of a film with the said copolymer (A).
- the copolymer (B) having an imide ring structure is preferably an acrylic resin having an imide ring structure in the structure.
- acrylic resin having an imide structure examples include (meth) acrylic resins having an imide ring structure described in JP2009-270021A, JP2010-117451A, and JP2013-109285A. .
- the (meth) acrylic resin having an imide ring structure is preferably a maleimide structure represented by the following general formula (1) or an acrylic resin having a glutarimide structure represented by the following general formula (2). .
- R 1 and R 2 in the general formula (1) are each independently a hydrogen atom or a methyl group.
- R 3 is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, a benzyl group, a phenyl group, a methoxyphenyl group, a trichlorophenyl group, an ethylphenyl group, a tolyl group, a naphthyl group, or a xylyl group.
- the ring structure represented by the general formula (1) is an N-substituted maleimide structure.
- the N-substituted maleimide structure can be formed, for example, by polymerizing an N-substituted maleimide such as phenylmaleimide and a (meth) acrylic acid ester.
- N-phenylmaleimide N-benzylmaleimide, N-cyclohexylmaleimide and N-methylmaleimide are preferred because the acrylic resin has excellent heat resistance.
- These second monomers may be used alone or in combination of two or more.
- Examples of the (meth) acrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, and methacrylic acid 2 -Ethylhexyl; cyclopentyl methacrylate, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, fine cyclooctyl methacrylate, tricyclododecyl methacrylate, isobornyl methacrylate, phenyl methacrylate, benzyl methacrylate, 1-methacrylate Examples include phenylethyl, 2-phenoxyethyl methacrylate, 3-phenylpropyl methacrylate, 2,4,6-tribromophenyl
- the acrylic resin is preferably made into a copolymer by further using other monomers.
- other monomers include styrene, vinyltoluene, ⁇ -methylstyrene, ⁇ -hydroxymethylstyrene, ⁇ -hydroxyethylstyrene, and chlorostyrene.
- Allyl alcohol such as acrylonitrile, methacrylonitrile, methyl vinyl ketone, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, methallyl alcohol, allyl alcohol, 2-hydroxymethyl-1-butene, acrylic acid, methacryl (Meth) acrylic acid such as acid, crotonic acid, 2- (hydroxymethyl) acrylic acid ester such as methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, 2- (hydroxyethyl) acrylic Acid etc.
- styrene, ⁇ -methylstyrene, acrylonitrile, methacrylonitrile and the like are preferable, and styrene is more preferable.
- These other units may be directly copolymerized or graft copolymerized in the maleimide acrylic resin.
- An acrylic resin whose ring structure is a maleimide structure can be produced, for example, by the method described in JP-A-57-153008 and JP-A-2007-31537.
- a copolymer of the monomer having the N-substituted maleimide structure and the other monomer for example, in order to improve adhesion to water glue, acrylonitrile or methacrylo From the viewpoint of adhesion to a nitrile unit such as nitrile and an active energy ray-curable adhesive, it is preferable to use a copolymer with an aromatic vinyl unit such as styrene or ⁇ -methylstyrene. -Phenylmaleimide-styrene copolymer, N-phenylmaleimide-styrene-acrylonitrile copolymer and the like.
- R 4 and R 5 in the general formula (2) are each independently a hydrogen atom or a methyl group
- R 6 is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, A benzyl group or a phenyl group.
- the ring structure represented by the general formula (2) is a glutarimide structure, and the glutarimide structure can be formed, for example, by imidizing a (meth) acrylic acid ester polymer with an imidizing agent such as methylamine.
- the acrylic resin having the glutarimide ring structure preferably contains an aromatic vinyl unit such as styrene or ⁇ -methylstyrene, and further, in order to improve adhesiveness, It preferably contains a nitrile unit such as acrylonitrile or methacrylonitrile.
- These other units may be directly copolymerized or graft copolymerized in the glutarimide resin.
- a (meth) acrylic resin having a glutarimide ring structure can be produced by, for example, the methods described in International Publication No. 2007/26659 and International Publication No. 2005/108438.
- the content ratio of the imide ring structure of the acrylic resin having an imide ring structure is preferably in the range of 5 to 90% by mass, more preferably in the range of 10 to 70% by mass.
- the content of the imide ring structure in the structure of the acrylic resin having an imide ring structure is 5% by mass or more, sufficient heat resistance, solvent resistance, and surface hardness can be obtained.
- the content ratio of the imide ring structure of the acrylic resin having an imide ring structure is 90% by mass or less, transparency and good film forming property can be obtained.
- the acrylic resin having an imide ring structure preferably has a weight average molecular weight in the range of 1,000 to 2,000,000, more preferably in the range of 5,000 to 1,000,000, still more preferably in the range of 10,000 to 500,000, and particularly preferably. It is in the range of 50,000 to 500,000.
- a weight average molecular weight within the above range is preferable from the viewpoint of moldability.
- the weight average molecular weight can be determined in terms of polystyrene by gel permeation chromatography (GPC system, manufactured by Tosoh Corporation) using tetrahydrofuran as a solvent.
- the acrylic resin having an imide structure preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 125 ° C. or higher, still more preferably 130 ° C. or higher, particularly preferably 135 ° C. or higher, and most preferably 140 ° C. or higher.
- Tg glass transition temperature
- Setting Tg in the above range is preferable from the viewpoint of obtaining a polarizing plate having small dimensional change and optical property change even in a high temperature environment.
- the upper limit of Tg of the acrylic resin having the imide ring structure is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability and the like.
- Copolymers (A) and (B) according to the present invention can be used in combination with other resins as long as the effects of the present invention are not impaired.
- other resins other styrene resins and (meth) acrylic resins can be preferably used.
- styrene resins may be those obtained by copolymerizing styrene monomers, unsaturated carboxylic acid monomers and / or unsaturated dicarboxylic anhydride monomers with other monomer components.
- Other monomers that can be copolymerized include alkyl methacrylates such as methyl methacrylate, cyclohexyl methacrylate, methylphenyl methacrylate, and isopropyl methacrylate, and alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate.
- Saturated carboxylic acid alkyl ester monomers such as N-phenylmaleimide and N-cyclohexylmaleimide; 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl- Examples thereof include conjugated dienes such as 1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like, and two or more of these may be copolymerized.
- (Meth) acrylic resin includes structural units derived from (meth) acrylic acid esters.
- (meth) acrylic acid esters include alkyl acrylates having 4 to 18 carbon atoms such as methyl acrylate, ethyl acrylate and butyl acrylate; and those having 5 to 18 carbon atoms such as methyl methacrylate, ethyl methacrylate and butyl methacrylate.
- Methacrylic acid alkyl esters are included. Of these, methyl methacrylate is preferable because it is easily polymerized. Another monomer may be used by 1 type and may use 2 or more types together.
- the (meth) acrylic resin may further contain a structural unit derived from another monomer as necessary.
- examples of other monomers include ⁇ , ⁇ -unsaturated acids such as acrylic acid and methacrylic acid; cyclics such as maleic anhydride, itaconic anhydride, glutaric anhydride, citraconic anhydride, aconitic anhydride, etc. Acid anhydride monomers; vinyl esters such as vinyl acetate and vinyl benzoate; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propio vinyl ether.
- Another monomer may be used by 1 type and may use 2 or more types together.
- the weight average molecular weight of the resin is preferably 100,000 or more, preferably 150,000 or more, and more preferably 200,000 to 1,500,000 in order to further improve the brittleness of the resulting film.
- the weight average molecular weight (Mw) of the resin is measured in the same manner as described above.
- the polarizing plate protective film of the present invention comprises a copolymer (A) obtained by polymerizing an aromatic vinyl monomer and an unsaturated nitrile monomer and a copolymer (B) having an imide ring structure in a mass ratio of A.
- : B 100: 0 to 50:50 is characteristic, and if it is within the range, it has high water resistance and heat resistance, and display unevenness (bend unevenness) of the liquid crystal display device occurs.
- a polarizing plate protective film having good adhesion to a polarizer can be obtained in combination with either water glue or an active energy ray-curable adhesive.
- the content ratio of the copolymer (A) is less than 50, the water resistance, heat resistance and toughness are inferior. Therefore, in order to express the effect of the present invention, the content mass ratio of the copolymer (A) needs to be within the above range.
- A: B is in the range of 90:10 to 55:45, and more preferably in the range of 80:20 to 60:40.
- the polarizing plate protective film of the present invention comprises a peeling aid, an antistatic agent, an antioxidant, an ultraviolet absorber, fine particles (matting agent) for imparting slipperiness, and an impact reinforcing material for enhancing toughness, if necessary. And various other additives.
- the film-like material containing the copolymer of the aromatic vinyl monomer and the unsaturated nitrile monomer according to the present invention has high adhesion to the metal support, so that it is easy to peel off from the metal support, and the elongation at the time of peeling is In order to make the thickness of the film obtained by suppressing the above, it is preferable to contain a peeling aid or an antistatic agent.
- the stripping assistant is at least one of acid, alcohol, metal salt, nonionic surfactant or nonreactive quaternary ammonium salt type surfactant having a linear or branched alkyl group having 8 to 22 carbon atoms. It is preferable that the releasability is enhanced by containing them in the range of 0.1 to 1.0% by mass with respect to the total mass of the copolymers (A) and (B).
- Examples of the compound include alkyl sulfonate and alkyl benzene sulfonate.
- Examples of the salt include sodium salt, potassium salt, amine salt, ammonium salt, phosphonium salt and the like.
- Specific examples include sodium decylsulfonate, sodium decylbenzenesulfonate, potassium decylbenzenesulfonate, sodium dodecylsulfonate, potassium dodecylsulfonate, sodium dodecylbenzenesulfonate, potassium dodecylbenzenesulfonate, tetrabutyl dodecylbenzenesulfonate.
- Examples of these commercially available products include Hostastat HS-1 manufactured by Clariant Japan Co., Ltd., Elecut S-412-2 and Elecut S-418 manufactured by Takemoto Yushi Co., Ltd., Neoperex G65 manufactured by Kao Co., Ltd., and the like. It is done.
- Examples of the alcohol include octan-1-ol, nonan-1-ol, decan-1-ol, undecan-1-ol, dodecan-1-ol, tridecan-1-ol, tetradecan-1-ol, pentadecane -1-ol, hexadecan-1-ol, heptadecan-1-ol, octadecan-1-ol, nonadecan-1-ol, Examples thereof include icosan-1-ol, heneicosan-1-ol, and docosan-1-ol, and octadecan-1-ol (stearyl alcohol) is preferred.
- nonionic surfactant as a peeling aid, for example, polyoxyalkylene glycol such as polyoxyethylene polyoxypropylene glycol, polyoxyalkylene styrenation such as polyoxyethylene styrenated phenyl ether, etc.
- Polyoxyalkylene glycols such as phenyl ether, polyoxyethylene tridecyl ether and polyoxyethylene lauryl ether, polyoxyalkylene glycols such as polyoxyethylene sorbitan monococoate, polyoxyethylene sorbitan monostearate and polyoxyethylene hydrogenated castor oil
- Nonionic surfactants, such as these are mentioned, These may be used independently and may use 2 or more types together. Examples of these commercially available products include Epan manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
- non-reactive quaternary ammonium salt type surfactant as a peeling aid, and among them, a non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups is useful.
- the surfactant is not particularly limited, and examples of the non-reactive quaternary ammonium salt type surfactant having one methyl group include polyoxypropylene methyldiethylammonium chloride, methyldiethyl (2-methoxyethyl).
- Ammonium chloride octyl bis polyoxyethylene methyl ammonium chloride, lauryl bis polyoxyethylene methyl ammonium chloride, oleyl bis polyoxyethylene methyl ammonium chloride, polyoxyethylene dodecyl monomethyl ammonium chloride, etc., which have two methyl groups
- reactive quaternary ammonium salt type surfactants include aliphatic alkyl quaternary ammonium salts such as octyldimethylethylammonium ethyl sulfate, lauric acid, and the like.
- the surfactant preferably contains an alkylene oxide (AO) group.
- alkylene oxide group those contained in either or both of an anionic component and a cationic component of the surfactant can be used.
- alkylene oxide (AO) group examples include polyoxypropylene methyldiethylammonium chloride, methyldiethyl (2-methoxyethyl) ammonium chloride, octyl bispolyoxyethylene methylammonium chloride, and lauryl bispolyoxyethylene.
- methylammonium chloride oleyl bispolyoxyethylene methylammonium chloride, polyoxyethylene dodecyl monomethylammonium chloride, and ethyldimethyl (2-methoxyethyl) ammonium chloride is also a more preferred embodiment.
- These surfactants may be used alone or in combination of two or more.
- non-reactive quaternary ammonium salt type surfactants commercially available products can be used.
- the trade name “ADEKA COAL CC-36” (number of methyl groups: 1, manufactured by ADEKA Corporation), “ADEKA COAL” CC-42 ”(number of methyl groups: 1 product, manufactured by ADEKA Corporation), trade name“ cationic L-207 ”(number of methyl groups: 1 product, manufactured by NOF Corporation), trade name“ Katiogen ES-L ”( Number of methyl groups: 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), trade name “Katiogen ES-O” (number of methyl groups: 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), trade name “Katiogen ES-OW” ( Number of methyl groups: 2 (Daiichi Kogyo Seiyaku Co., Ltd.), trade name “Katiogen ES-WS-L-9” (2
- Antioxidant in this invention, what is generally known can be used as an antioxidant.
- lactone, sulfur, phenol, double bond, hindered amine, and phosphorus compounds can be preferably used.
- Irgafos XP40, Irgafos XP60 commercially available from BASF Japan Ltd. can be mentioned.
- the phenolic compound preferably has a 2,6-dialkylphenol structure.
- “Irganox 1076”, “Irganox 1010” commercially available from BASF Japan KK, and commercially available from ADEKA Corporation.
- “Adeka Stub AO-50” can be mentioned.
- Examples of the phosphorus compound include “Sumizer GP” commercially available from Sumitomo Chemical Co., Ltd., “ADK STAB PEP-24G”, “ADK STAB PEP-36”, and “ADK STAB 3010” commercially available from ADEKA Corporation. “IRGAFOS P-EPQ” commercially available from BASF Japan Ltd. and “GSY-P101” commercially available from Sakai Chemical Industry Ltd.
- hindered amine compound examples include “Tinvin 144” and “Tinvin 770” commercially available from BASF Japan, and “ADK STAB LA-52” commercially available from ADEKA.
- sulfur compound examples include “Sumilizer TPL-R” and “Sumilizer TP-D” commercially available from Sumitomo Chemical Co., Ltd.
- the above-mentioned double bond compound is commercially available from Sumitomo Chemical Co., Ltd. under the trade names of “Sumilizer GM” and “Sumilizer GS”.
- the polarizing plate protective film according to the present invention preferably contains an ultraviolet absorber, and applicable ultraviolet absorbers include ultraviolet absorbers such as benzotriazole, 2-hydroxybenzophenone, salicylic acid phenyl ester, and triazine. Agents.
- 2- (5-methyl-2-hydroxyphenyl) benzotriazole 2- [2-hydroxy-3,5-bis ( ⁇ , ⁇ -dimethylbenzyl) phenyl] -2H-benzotriazole
- 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone And benzophenones.
- UV absorbers for example, Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928, etc. manufactured by BASF Japan, or 2,2 '-Methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (molecular weight 659; examples of commercially available products are manufactured by ADEKA Corporation LA31) can be preferably used.
- matting agent In the present invention, it is preferable to add a matting agent in order to impart slipperiness to the polarizing plate protective film.
- the matting agent used in the present invention may be either an inorganic compound or an organic compound as long as it does not impair the transparency of the resulting film and has heat resistance in the film forming process. These matting agents can be used alone or in combination of two or more.
- High transparency and slipperiness can be achieved at the same time by using particles having different particle sizes and shapes (for example, needle shape and spherical shape).
- silicon dioxide is particularly preferably used from the viewpoint of excellent transparency (haze).
- silicon dioxide examples include Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (above, Nippon Aerosil Co., Ltd.), Sea Hoster KEP-10, Sea Hoster KEP -30, Seahoster KEP-50 (above, manufactured by Nippon Shokubai Co., Ltd.), Silo Hovic 100 (produced by Fuji Silysia), Nip Seal E220A (produced by Nippon Silica Industry), Admafine SO (produced by Admatechs), etc. A commercial item etc. can be used preferably.
- the shape of the matting agent particles can be used without particular limitation, such as indefinite shape, needle shape, flat shape, and spherical shape.
- the use of spherical particles is particularly preferable because the resulting film can have good transparency.
- the size of the matting agent particles is preferably smaller than the wavelength of visible light because the light is scattered and the transparency is lowered when the particle size is close to the wavelength of visible light. It is preferable that it is 2 or less. However, if the size of the matting agent particles is too small, the effect of improving the slipping property may not be exhibited. Therefore, the particle diameter is particularly preferably in the range of 80 to 180 nm.
- the particle size means the size of the aggregate when the particle is an aggregate of primary particles. Moreover, when a particle is not spherical, it means the diameter of a circle corresponding to the projected area.
- the polarizing plate protective film according to the present invention may contain at least one of core / shell type acrylic fine particles, a styrene-conjugated diene compound, or a butyl acrylate compound as an impact reinforcing material in order to increase impact resistance. preferable.
- core / shell type acrylic fine particles are obtained by polymerizing a mixture of 80 to 98.9% by weight of methyl methacrylate, 1 to 20% by weight of alkyl acrylate and 0.01 to 0.3% by weight of a polyfunctional grafting agent. Obtained by polymerizing a mixture of 75 to 98.5% by mass of an alkyl acrylate, 0.01 to 5% by mass of a polyfunctional crosslinking agent, and 0.5 to 5% by mass of a polyfunctional grafting agent. And an outermost hard layer obtained by polymerizing a mixture of 80 to 99% by weight of methyl methacrylate and 1 to 20% by weight of alkyl acrylate.
- the styrene-conjugated diene compound is preferably a styrene-butadiene copolymer.
- the copolymer may be a rubber-like elastic body or an elastic organic fine particle.
- the elastic organic fine particle is preferably a core-shell type particle.
- the core part is preferably composed of a soft polymer; and the shell part covering the periphery of the core part is preferably composed of another polymer having high compatibility with the copolymer according to the present invention and other resins.
- the soft polymer includes a structural unit derived from a conjugated diene monomer and, if necessary, a structural unit derived from another monomer.
- the conjugated diene monomer include 1,3-butadiene (hereinafter sometimes simply referred to as “butadiene”), isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, -Chloro-1,3-butadiene, myrcene and the like are included, and butadiene and isoprene are preferable.
- Examples of other monomers include styrene components such as styrene and ⁇ -methylstyrene.
- the content ratio of the structural unit derived from the conjugated diene monomer in the soft polymer is usually 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more.
- Examples of other polymers include copolymers of acrylonitrile and styrene, and polymers mainly composed of methacrylic acid esters such as methyl methacrylate.
- the elastic organic fine particles preferably have a volume average particle size of 0.35 ⁇ m or less, more preferably 0.01 to 0.35 ⁇ m, and still more preferably 0.05 to 0.30 ⁇ m. If the particle size is a certain value or more, sufficient impact absorbability can be imparted to the film; if the particle size is a certain value or less, the transparency of the resulting film is hardly impaired.
- Commercially available products include, for example, Metabrene C-140A, C-215A (manufactured by Mitsubishi Rayon Co., Ltd.), Toughprene 126, Asaflex 800, Asaflex 825 (manufactured by Asahi Kasei Chemicals Corporation), TR2000, TR2250. (Above, manufactured by JSR Corporation).
- Examples of other rubber-like elastic bodies include acrylate-based rubber-like polymers, and rubber-like polymers containing acrylate-based polymers containing butyl acrylate as the main component are preferred.
- the rubber-like elastic body using butyl acrylate may be elastic particles or may be a layered structure of two types of polymers.
- a typical example is a grafted rubber elastic component of alkyl acrylate such as butyl acrylate and styrene, and a hard resin layer made of a copolymer of polymethyl methacrylate and / or methyl methacrylate and alkyl acrylate in a core / shell structure. And elastic particles forming the.
- the content of the shock absorbing material is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass with respect to the total amount with the copolymer and other resins according to the present invention. .
- the refractive index is the same as that of the styrene-acrylonitrile copolymer used in the present invention, or the difference in refractive index is ⁇ 0.01 or less. From the viewpoint of maintaining the transparency of the film.
- a method for producing the polarizing plate protective film of the present invention the usual inflation method, T-die method, calendar method, cutting method, casting method, emulsion method, hot press method, etc. can be used, but coloring suppression From the viewpoints of suppressing foreign matter defects, optical defects such as die lines, etc., a film casting method can be selected from a solution casting film forming method and a melt casting film forming method, and particularly a solution casting film forming method. In addition to the effect of controlling the resin distribution state to suppress panel bend, a uniform and smooth surface can be obtained, and this is preferable from the viewpoint of reducing haze and yellow index (YI).
- YI yellow index
- the production of the polarizing plate protective film of the present invention is a step of preparing a dope by dissolving at least a copolymer according to the present invention, compounds such as other resins and additives in a solvent, and filtering the prepared dope.
- a step of casting on a drum-shaped metal support to form a web a step of peeling the formed web from the metal support to form a film, a step of stretching and drying the film, and a cooling of the dried film It is performed by a step of winding it into a post-roll shape.
- any organic solvent useful for forming a dope can be used without limitation as long as it dissolves a resin and other compounds simultaneously.
- methylene chloride as a non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, etc.
- methylene chloride, methyl acetate, ethyl acetate, and acetone can be preferably used as the main solvent. Particularly preferably
- the dope preferably contains a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in the range of 1 to 40% by mass.
- a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in the range of 1 to 40% by mass.
- the web gels, and peeling from the metal support becomes easy.
- the proportion of alcohol is small, the resin and other compounds can be dissolved in a non-chlorine organic solvent system.
- the dope having an alcohol concentration in the range of 0.5 to 15.0% by mass is formed from the viewpoint of improving the flatness of the obtained polarizing plate protective film. The method to do can be applied.
- a dope composition in which a resin and other compounds are dissolved in a total amount of 15 to 45% by mass in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms.
- a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms Preferably there is.
- linear or branched aliphatic alcohol having 1 to 4 carbon atoms examples include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Methanol and ethanol are preferred because of the stability, boiling point of these inner dopes, and good drying properties.
- a method carried out at normal pressure a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9-95557
- Various melting methods such as a method of performing a cooling dissolution as described in JP-A-9-95538, a method of performing at a high pressure as described in JP-A-11-21379, In particular, a method of pressurizing at a temperature equal to or higher than the boiling point of the main solvent is preferable.
- the concentration of the resin in the dope is preferably in the range of 10 to 40% by mass.
- the filtration of the dope it is preferable to filter the dope with a filter medium having a 90% collection particle diameter of 10 to 100 times the average particle diameter of the fine particles, for example, in the main filter 3 having a leaf disk filter.
- the filter medium used for filtration preferably has a low absolute filtration accuracy.
- the absolute filtration accuracy is too small, the filter medium is likely to be clogged, and the filter medium must be frequently replaced. There is a problem of lowering productivity.
- the filter medium used for the dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably in the range of 0.001 to 0.008 mm, and more preferably in the range of 0.003 to 0.006 mm.
- a filter medium is more preferable.
- the material of the filter medium there are no particular restrictions on the material of the filter medium, and normal filter media can be used. However, plastic fiber filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel fibers are used to remove fibers. This is preferable.
- the flow rate of the dope during filtration is preferably 10 to 80 kg / (h ⁇ m 2 ), preferably 20 to 60 kg / (h ⁇ m 2 ).
- the flow rate of the dope at the time of filtration is 10 kg / (h ⁇ m 2 ) or more, it becomes efficient productivity, and the flow rate of the dope at the time of filtration is within 80 kg / (h ⁇ m 2 ). If so, the pressure applied to the filter medium is appropriate, and the filter medium is not damaged, which is preferable.
- the filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and even more preferably 2500 kPa or less.
- the filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.
- FIG. 1 is a schematic view showing an example of a solution casting film forming process flow applicable to the production of the polarizing plate protective film of the present invention.
- the large agglomerates are removed from the dope prepared in the charging kettle 41 by the filter 44 and fed to the stock kettle 42. Thereafter, various additive solutions are added from the stock kettle 42 to the main dope dissolving kettle 1.
- the main dope is filtered by the main filter 3, and a matting agent dispersion liquid, an ultraviolet absorber additive liquid, and the like are added in-line through the conduit 16.
- the main dope may contain about 10 to 50% by weight of recycled material.
- the return material is, for example, a product obtained by finely pulverizing the polarizing plate protective film of the present invention, which occurs when the polarizing plate protective film is formed.
- the raw material for the polarizing plate protective film exceeding the value is used.
- a resin and other compounds previously pelletized can be preferably used as a raw material of the resin used for preparing the dope.
- the metal support in the casting process is preferably a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support.
- the cast width can be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, more preferably in the range of 2 to 2.8 m.
- the surface temperature of the metal support in the casting step is set in the range of ⁇ 50 ° C. to below the temperature at which the solvent boils and does not foam, more preferably in the range of ⁇ 30 to 100 ° C. A higher temperature is preferred because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate.
- a preferable support temperature is appropriately determined at 0 to 100 ° C., and more preferably within a range of 5 to 30 ° C.
- the method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short.
- ⁇ Pressure dies that can adjust the slit shape of the die base and make the film thickness uniform are preferred.
- the pressure die include a coat hanger die and a T die, and any of them is preferably used.
- the surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and laminated.
- the web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or heat by means such as infrared rays.
- Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process as a film.
- the temperature at the peeling position on the metal support is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C.
- the amount of residual solvent at the time of peeling of the web on the metal support at the time of peeling is preferably 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, and the like.
- the amount of solvent is determined.
- the residual solvent amount of the web is defined by the following formula (Z).
- Residual solvent amount (%) (mass before web heat treatment ⁇ mass after web heat treatment) / (mass after web heat treatment) ⁇ 100 Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.
- peeling tension when peeling the metal support from the film is usually in the range of 196 to 245 N / m. However, if wrinkles are likely to occur during peeling, peeling may be done with a tension of 190 N / m or less. preferable.
- the temperature at the peeling position on the metal support is preferably in the range of ⁇ 50 to 40 ° C., more preferably in the range of 10 to 40 ° C., and in the range of 15 to 30 ° C. Is most preferred.
- the drying step can be divided into a preliminary drying step and a main drying step.
- the web obtained by peeling from the metal support is dried.
- the web may be dried while being conveyed by a large number of rollers arranged above and below, or may be dried while being conveyed while fixing both ends of the web with clips like a tenter dryer. .
- the means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roller, microwave, or the like, but it is preferably performed with hot air in terms of simplicity.
- the drying temperature in the web drying step is preferably a glass transition point of the film of ⁇ 5 ° C. or lower, and it is effective to perform a heat treatment within a range of 10 minutes to 60 minutes at a temperature of 100 ° C. or higher. Drying is performed at a drying temperature in the range of 100 to 200 ° C, more preferably in the range of 110 to 160 ° C.
- the polarizing plate protective film of the present invention can control the orientation of molecules in the film by stretching, and can improve planarity or obtain toughness.
- the polarizing plate protective film of the present invention is preferably stretched in the longitudinal direction (also referred to as MD direction) and / or the width direction (also referred to as TD direction), and at least 1 in the longitudinal direction or the width direction as a stretching ratio. It is preferable to stretch within a range of 0.01 to 10 times.
- the stretching operation may be performed in multiple stages.
- simultaneous biaxial stretching may be performed or may be performed stepwise.
- stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible.
- the residual solvent amount at the start of stretching is preferably in the range of 2 to 10% by mass.
- the amount of the residual solvent is 2% by mass or more, the film thickness deviation is small and is preferable from the viewpoint of flatness, and if it is within 10% by mass, the unevenness of the surface is reduced and the flatness is improved.
- the polarizing plate protective film of the present invention has a film transition temperature in the MD direction and / or TD direction, preferably in the TD direction so that the film thickness after stretching is in a desired range. It is preferable to stretch in the temperature range of Tg + 15) to (Tg + 50) ° C. If it extends in the said temperature range, since a extending
- the stretching temperature is preferably in the range of (Tg + 20) to (Tg + 40) ° C.
- the web is preferably stretched at least in the MD direction or TD direction within a range of 1.01 to 10 times, but the stretching range is 1.1 to 10 with respect to the original width.
- the range is preferably double, and more preferably 1.2 to 8 times. If it is in the said range, a film will become toughness, a film can be thinned, and the flatness of a film can be improved.
- peeling is preferably performed at a peeling tension of 130 N / m or more, particularly preferably 150 to 170 N / m. Since the web after peeling is in a high residual solvent state, stretching in the MD direction can be performed by maintaining the same tension as the peeling tension. As the web dries and the residual solvent amount decreases, the stretch ratio in the MD direction decreases.
- the drawing of MD direction can use the roller drawing machine using the peripheral speed difference of a roller, and a draw ratio can be calculated from the rotational speed of a belt support body, and the operating speed of a roller drawing machine.
- the entire drying process or a part of the process as shown in Japanese Patent Application Laid-Open No. 62-46625 is held in the width direction by holding the width ends of the web with clips or pins.
- a method of drying while drying (called a tenter method), among them, a tenter method using a clip and a pin tenter method using a pin are preferably used.
- stretching in the TD direction stretching in the width direction of the film at a stretching speed of 250 to 500% / min is preferable from the viewpoint of improving the flatness of the film.
- the stretching speed is 250% / min or more, the planarity is improved and the film can be processed at a high speed, which is preferable from the viewpoint of production aptitude, and if it is within 500% / min, the film is broken. Can be processed without any problem.
- a preferable stretching speed is in the range of 300 to 400% / min.
- the stretching speed is defined by the following formula (E).
- the polarizing plate protective film of the present invention has a retardation value (Ro) defined by the following formula (i) in the range of 0 to 70 nm, and the retardation value (Rt) defined by the following formula (ii)
- Ro retardation value
- Rt retardation value
- a thickness in the range of ⁇ 50 to 10 nm is particularly preferable when the polarizing plate protective film does not require retardation.
- the polarizing plate protective film can be stretched while adjusting the stretching ratio at least in the MD direction or the TD direction.
- n x represents a refractive index in the direction x in which the refractive index is maximized in the plane direction of the film.
- n y in-plane direction of the film, the refractive index in the direction y perpendicular to the direction x.
- nz represents the refractive index in the thickness direction z of the film.
- d represents the thickness (nm) of the film.
- the knurling process can be formed by pressing a heated embossing roller. Fine embossing is formed on the embossing roller, and by pressing the embossing roller, unevenness can be formed on the film and the end can be made bulky.
- the height of the knurling at both ends of the width of the polarizing plate protective film of the present invention is preferably 4 to 20 ⁇ m and the width is 5 to 20 mm.
- the knurling process is preferably provided after the drying in the film forming process and before winding.
- Winding step This is a step of winding as a film after the residual solvent amount in the web is 2% by mass or less, and the film having good dimensional stability by making the residual solvent amount 0.4% by mass or less. Can be obtained.
- a winding method As a winding method, a commonly used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, etc., and these may be used properly.
- the polarizing plate protective film of the present invention can also be formed by a melt casting method.
- the melt casting method refers to heating and melting a composition containing the copolymer and other compounds according to the present invention to a temperature showing fluidity, and then casting the fluid melt.
- melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy.
- a plurality of raw materials used for melt extrusion are usually preferably kneaded and pelletized in advance.
- Pelletization may be performed by a known method.
- the copolymer according to the present invention and other compounds are fed to an extruder with a feeder and kneaded using a uniaxial or biaxial extruder, and formed into a strand form from a die. It can be done by extrusion, water cooling or air cooling and cutting.
- Additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.
- a small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.
- the extruder is preferably processed at a temperature as low as possible so that it can be pelletized so that the shearing force is suppressed and the resin does not deteriorate (molecular weight reduction, coloring, gel formation, etc.).
- a temperature as low as possible so that it can be pelletized so that the shearing force is suppressed and the resin does not deteriorate (molecular weight reduction, coloring, gel formation, etc.).
- the resin does not deteriorate (molecular weight reduction, coloring, gel formation, etc.).
- a twin screw extruder it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.
- Film formation is performed using the pellets obtained as described above.
- the raw material powder can be directly fed to the extruder by a feeder without being pelletized to form a film as it is.
- the pellets are melted at a temperature of about 200 to 300 ° C., filtered through a leaf disk type filter or the like to remove foreign matter, and then flowed from the T die into a film. Then, the film is nipped with a cooling roller and an elastic touch roller, and solidified on the cooling roller to form a polarizing plate protective film.
- the extrusion flow rate is preferably adjusted stably by introducing a gear pump or the like.
- a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances.
- the stainless steel fiber sintered filter is a united stainless steel fiber body that is intricately intertwined and compressed, and the contact points are sintered and integrated. The density of the fiber is changed depending on the thickness of the fiber and the amount of compression, and the filtration accuracy is improved. Can be adjusted.
- Additives such as antioxidants and particles may be mixed with the resin in advance, or may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer.
- the polarizing plate protective film temperature on the touch roller side when the polarizing plate protective film is nipped by the cooling roller and the elastic touch roller is preferably set to Tg or more (Tg + 110 ° C.) or less of the film.
- a known roller can be used as the roller having an elastic surface used for such purposes.
- the elastic touch roller is also called a pinching rotary body.
- a commercially available one can be used as the elastic touch roller.
- the film obtained as described above is stretched by the stretching operation after passing through the step of contacting the cooling roller.
- the stretching method a known roller stretching machine or tenter can be preferably used.
- the stretching temperature is usually preferably in the temperature range of Tg to (Tg + 60) ° C. of the resin constituting the film.
- the end Before winding, the end may be slit and cut to the product width, and knurled (embossed) may be applied to both ends to prevent sticking and scratching during winding.
- the knurling method can be performed by heating or pressurizing using a metal ring having an uneven pattern on the side surface.
- the polarizing plate protective film has deform
- the polarizing plate protective film of the present invention preferably has a haze of 1.0% or less, and more preferably 0.5% or less. By setting the haze to 1.0% or less, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as a film for optical applications.
- the haze is measured with a haze meter (turbidity meter) (model: NDH 2000, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K-7136.
- YI is preferably 1.0 or less, and more preferably 0.5 or less.
- YI is preferably 1.0 or less, and more preferably 0.5 or less.
- the yellow index (YI) referred to in the present invention can be obtained by the method described in JIS standard K7105-6.3.
- the color tristimulus values X, Y, and Z are obtained using a spectrophotometer U-3200 manufactured by Hitachi, Ltd. and the attached saturation calculation program, etc. The yellow index value is obtained.
- the total light transmittance of the polarizing plate protective film is preferably 90% or more, more preferably 93% or more.
- the total light transmittance can be measured in accordance with JIS7573 “Plastics—Determination of total light transmittance and total light reflectance”.
- the equilibrium water content at 25 ° C. and relative humidity 55% is preferably 3% or less, and more preferably 2% or less.
- the equilibrium moisture content is preferable to easily cope with a change in humidity and to hardly change the optical characteristics and dimensions.
- the polarizing plate protective film of the present invention is preferably long, specifically, preferably has a length of about 100 to 10,000 m, and is wound up in a roll shape.
- the width of the polarizing plate protective film of the present invention is preferably 1 m or more, more preferably 1.4 m or more, and particularly preferably 1.4 to 4 m.
- the film thickness is preferably in the range of 10 to 100 ⁇ m, more preferably in the range of 10 to 60 ⁇ m, from the viewpoint of thinning the display device and productivity. If the film thickness is 10 ⁇ m or more, a certain level of film strength and retardation can be expressed. When the film thickness is 100 ⁇ m or less, the film has a desired retardation and can be applied to make the polarizing plate and the display device thinner. In order to balance the bend unevenness and the thin film, the thickness is preferably in the range of 20 to 50 ⁇ m.
- the moisture permeability at 40 ° C. and 90% RH of the polarizing plate protective film is preferably 300 g / m 2 ⁇ day or less, more preferably 200 g / m 2 ⁇ day or less, and 10 to 100 g / m 2 ⁇ day. This range is particularly preferable for suppressing bend unevenness. This is for suppressing the change in the size of the polarizer due to the transmitted water in a high temperature and high humidity environment.
- the moisture permeability is measured under the condition of 40 ° C. and 90% RH in accordance with the method described in JIS Z 0208.
- the moisture permeability of the polarizing plate protective film can be adjusted by, for example, the content ratio of the structural unit derived from the aromatic vinyl monomer in the copolymer. In order to reduce the moisture permeability, for example, the content ratio of the structural unit derived from the aromatic vinyl monomer in these polymers may be increased.
- the tear strength of the polarizing plate protective film at 23 ° C. and 55% RH is preferably 15 mN or more, more preferably 20 mN or more, and further preferably 30 mN or more.
- the upper limit of the tear strength is, for example, about 50 mN.
- the tear strength of the polarizing plate protective film can be measured by the following method. That is, the polarizing plate protective film is cut out to obtain a sample film having a width of 50 mm and a length of 64 mm. The sample film is conditioned at 23 ° C. and 55% RH for 24 hours, and then the Elmendorf tear strength is measured according to ISO 6383 / 2-1983. The Elmendorf tear strength can be measured using a Toyo Seiki Co., Ltd. light weight tear tester. The tear strength was measured for each of the case where the film was torn in the length direction (MD direction) of the film and the width direction (TD direction) of the film at 23 ° C. and 55% RH. Desired.
- the tear strength of the polarizing plate protective film can be adjusted by, for example, the molecular weight of a copolymer or other resin.
- the molecular weight of the copolymer or other resin may be increased.
- the polarizing plate protective film of the present invention is characterized in that it can be bonded to a polarizer by using either a polyvinyl alcohol-based adhesive or an active energy ray-curable adhesive.
- the polarizing plate protective film of the present invention is bonded to at least one surface of the polarizer using water glue or an ultraviolet curable adhesive.
- a cellulose ester phase difference film is bonded to the polarizer using water glue or an active energy ray curable adhesive. Bonding is preferred from the viewpoints of handleability, reworkability, and optical properties.
- the outer film is a film having low moisture permeability
- the inner film is a cellulose ester film
- the influence of moisture from the outside is reduced.
- the internal moisture is easily released, and the durability of the polarizing plate against humidity fluctuation is improved overall.
- the polarizing plate of the present invention has a configuration in which the polarizer is sandwiched between the polarizing plate protective film of the present invention and the cellulose ester phase difference film, which improves durability, suppresses bend unevenness, and is excellent. From the viewpoint of providing visibility to the liquid crystal display device, this is a preferred embodiment.
- the viewing side film of the polarizing plate is an antiglare layer or a clear hard coat layer, an antireflection layer, an antistatic layer, an antifouling layer, etc. It is preferable to provide a functional layer.
- the polarizer which is the main component of the polarizing plate of the present invention, is an element that passes only light having a plane of polarization in a certain direction
- a typical known polarizer is a polyvinyl alcohol polarizing film.
- the polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.
- polarizer a polarizer obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxial stretching or dyeing and then uniaxially stretching and then preferably performing a durability treatment with a boron compound may be used.
- the film thickness of the polarizer is in the range of 5 to 15 ⁇ m, and particularly preferably in the range of 5 to 10 ⁇ m.
- the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%
- the degree of polymerization is 2000 to 4000
- the degree of saponification is 99.0 to 99.99 mol%.
- the ethylene-modified polyvinyl alcohol is also preferably used.
- an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used.
- a polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has little color unevenness, and is particularly preferably used for a large liquid crystal display device.
- the polarizing plate of the present invention is preferably a thin film, and the thickness of the polarizer is particularly preferably in the range of 2 to 15 ⁇ m from the viewpoint of achieving both the strength of the polarizing plate and the reduction of the thickness.
- a laminated film type polarizer can be produced by the method described in JP 2011-1000016 A, JP 4691205 A, JP 4751481 A, and JP 4804589 A. Is preferred.
- the polarizing plate of the present invention can be produced by a general method.
- the polarizer side of the polarizing plate protective film of the present invention is subjected to surface treatment such as corona treatment, plasma treatment, or excimer light treatment, and is immersed in an iodine solution and stretched on at least one surface of the polarizer. It can bond together using chemical-ized polyvinyl alcohol aqueous solution (water paste).
- the following retardation film and polarizer are similarly bonded by a completely saponified polyvinyl alcohol aqueous solution (water paste).
- the retardation film is a cellulose ester film
- the surface is preferably saponified.
- the direction of bonding with the polarizer is preferably bonded so that, for example, the absorption axis of the polarizer and the slow axis of the polarizing plate protective film are orthogonal to each other.
- polarizing plate protective film can be bonded to the other surface of the polarizer.
- a conventional polarizing plate protective film a commercially available cellulose ester film (for example, Konica Minoltak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC4FR, KC4KR, KC4DR, KC4SR, KC8UY, KC6UY, KC6UY, KC4 KC8UE, KC8UY-HA, KC8UX-RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Co., Ltd.) are preferably used.
- a retardation film is preferably disposed on one surface of the polarizer in order to improve visibility such as widening the viewing angle and improving contrast provided in the VA liquid crystal auxiliary display device.
- the retardation film is not particularly limited, and may be, for example, a cellulose ester film.
- cellulose esters contained in the cellulose ester film include cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose acetate propionate benzoate, cellulose propionate, and cellulose butyrate.
- the cellulose ester preferably has a total acyl group substitution degree in the range of 1.5 to 2.5, and more preferably satisfies the following formulas (a) and (b).
- Mw weight average molecular weight of the cellulose ester is preferably 75,000 or more, more preferably 100,000 to 1,000,000, from the viewpoints of film strength and appropriate viscosity during film formation. It is particularly preferable that it is ⁇ 500,000.
- the cellulose ester film may be a single layer film or a laminated film.
- the cellulose ester film is a laminated film, it is a laminate of a core layer mainly composed of a cellulose ester having a low degree of substitution and a skin layer mainly composed of a cellulose ester having a high degree of substitution disposed on both sides thereof. It is preferable.
- the cellulose ester having a low degree of substitution preferably satisfies the above formulas (a) and (b), and the cellulose ester having a high degree of substitution preferably has a total acyl group substitution degree of more than 2.5, and preferably 2.7. It is preferably within the range of ⁇ 2.98, and all the acyl groups contained in the cellulose ester are preferably acetyl groups.
- the retardation of the retardation film can be set according to the type of liquid crystal cell to be combined.
- the retardation value Ro in the in-plane direction measured at 23 ° C. and 55% RH and at a wavelength of 590 nm is preferably in the range of 30 to 150 nm, and the retardation value Rt in the thickness direction is 70 to A range of 300 nm is preferable.
- a retardation film having a retardation value in the above range can be preferably used as a retardation film such as a VA liquid crystal cell.
- Ro and Rt are defined as described above.
- the thickness of the retardation film is not particularly limited, but is preferably in the range of 10 to 250 ⁇ m, more preferably in the range of 10 to 100 ⁇ m, and particularly preferably in the range of 30 to 60 ⁇ m. preferable.
- the polarizing plate protective film of this invention demonstrated above and at least one surface of a polarizer are bonded by the active energy ray hardening-type adhesive agent.
- the said retardation film and polarizer are similarly bonded by the active energy ray hardening-type adhesive agent.
- the active energy ray-curable adhesive to the bonding of the polarizing plate protective film and the polarizer of the present invention, or the bonding of the retardation film and the polarizer, with high productivity, It is easy to suppress the deformation of the polarizing plate, and it is possible to obtain characteristics with excellent flatness.
- composition of active energy ray-curable adhesive examples include a photo radical polymerization composition utilizing photo radical polymerization, a photo cation polymerization composition utilizing photo cation polymerization, and photo radical polymerization.
- a hybrid composition using both photocationic polymerization and photocationic polymerization is known.
- the radical photopolymerizable composition includes a radically polymerizable compound containing a polar group such as a hydroxy group and a carboxy group described in JP-A-2008-009329 and a radically polymerizable compound not containing a polar group at a specific ratio.
- Composition) and the like are known.
- the radical polymerizable compound is preferably a compound having a radical polymerizable ethylenically unsaturated bond.
- the compound having an ethylenically unsaturated bond capable of radical polymerization include a compound having a (meth) acryloyl group.
- Examples of the compound having a (meth) acryloyl group include an N-substituted (meth) acrylamide compound and a (meth) acrylate compound.
- (Meth) acrylamide means acrylamide or methacrylamide.
- cationic photopolymerization type composition as disclosed in JP2011-08234A, ( ⁇ ) a cationic polymerizable compound, ( ⁇ ) a cationic photopolymerization initiator, and ( ⁇ ) a wavelength longer than 380 nm.
- an active energy ray-curable adhesive composition containing each of the components of a photosensitizer exhibiting maximum absorption in the light of ( ⁇ ) and a naphthalene-based photosensitization aid.
- active energy ray-curable adhesives may be used.
- the active ray curable adhesive used in the present invention it is preferable to use an ultraviolet curable adhesive as described in the above publication.
- Adhesive application step of applying the following active energy ray-curable adhesive to at least one of the adhesive surfaces of the polarizer and the polarizing plate protective film of the present invention; 2) A bonding step in which a polarizer and a polarizing plate protective film are bonded and bonded together via an adhesive layer; 3) A curing step of curing the adhesive layer in a state where the polarizer and the polarizing plate protective film are bonded via the adhesive layer, Can be mentioned.
- Pretreatment process an easy adhesion treatment is performed on the surface of the polarizing plate protective film adhered to the polarizer.
- the polarizing plate protective film 102 and the retardation film 105 are bonded to both surfaces of the polarizer 104 via the active energy ray curable adhesives 103 ⁇ / b> A and 103 ⁇ / b> B, the respective polarizing plates are used.
- the adhesion surface of the protective film 102 and the retardation film 105 is subjected to easy adhesion treatment.
- the surface subjected to the easy adhesion treatment is treated as a bonding surface with the polarizer, and therefore the active energy ray-curable resin layer 103A is bonded to both surfaces of the polarizing plate protective film.
- the surface to be treated is subjected to an easy adhesion treatment.
- Examples of the easy adhesion treatment include corona treatment, plasma treatment, and excimer light treatment.
- the active energy ray-curable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the polarizing plate protective film.
- an active energy ray hardening-type adhesive directly on the surface of a polarizer or a polarizing plate protective film
- various wet coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used.
- the method of pressurizing with a roller etc. and spreading uniformly can also be utilized.
- Bonding process After apply
- this bonding step for example, when an active energy ray-curable adhesive is applied to the surface of the polarizer in the previous application step, a polarizing plate protective film is superimposed there.
- a polarizer is superimposed thereon.
- an active energy ray hardening-type adhesive agent is cast between a polarizer and a polarizing plate protective film, a polarizer and a polarizing plate protective film are piled up in that state.
- both sides When a polarizing plate protective film and a retardation film are bonded to both sides of a polarizer, and both surfaces use an active energy ray-curable adhesive, an active energy ray-curable adhesive is applied to both sides of the polarizer.
- a polarizing plate protective film and a retardation film are superimposed on each other.
- both sides when a polarizing plate protective film is superimposed on one side of the polarizer, the polarizing plate protective film and the retardation film are provided on both sides of the polarizer and the polarizing plate protective film side.
- pressure is applied between the polarizing plate protective film and the retardation film side of both surfaces with a roller or the like.
- the material of the roller metal, rubber or the like can be used.
- the rollers arranged on both sides may be made of the same material or different materials.
- an active energy ray curable adhesive is irradiated with active energy rays, and a cationic polymerizable compound (for example, an epoxy compound or an oxetane compound) or a radical polymerizable compound (for example, an acrylate compound or an acrylamide compound).
- a cationic polymerizable compound for example, an epoxy compound or an oxetane compound
- a radical polymerizable compound for example, an acrylate compound or an acrylamide compound.
- Visible light, ultraviolet rays, X-rays, electron beams, etc. can be used as the active energy rays applied for curing, but electron beams and ultraviolet rays are generally preferred because they are easy to handle and have a sufficient curing rate. Used.
- a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.
- An ArF excimer laser, a KrF excimer laser, an excimer lamp, synchrotron radiation, or the like can also be used.
- an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a xenon arc, and a metal halide lamp are preferably used.
- the electron beam 50 to 1000 keV emitted from various electron beam accelerators such as Cockloft Walton type, Bande graph type, resonance transformation type, insulation core transformation type, linear type, dynamitron type, and high frequency type, preferably 100
- An electron beam having an energy in the range of up to 300 keV can be mentioned.
- the acceleration voltage is preferably in the range of 5 to 300 kV, more preferably in the range of 10 to 250 kV. If the acceleration voltage is 5 kV or more, the electron beam can reach the adhesive sufficiently to obtain the desired curing conditions, and if the acceleration voltage is 300 kV or less, the penetration force through the bonding unit becomes excessively strong. It can suppress that a transparent polarizing plate protective film and a polarizer are damaged.
- the irradiation dose is in the range of 5 to 100 kGy, more preferably in the range of 10 to 75 kGy.
- the active energy ray-curable adhesive is sufficiently cured.
- the irradiation dose is 100 kGy or less, the polarizing plate protective film and the polarizer are not damaged, and the mechanical strength is reduced. Changes can be prevented, and predetermined optical characteristics can be obtained.
- the dose of ultraviolet rays is preferably in accumulated light amount is within the range of 50 ⁇ 1500mJ / cm 2, and even more preferably in the range of 100 ⁇ 500mJ / cm 2.
- the line speed depends on the curing time of the active energy ray-curable adhesive, but is preferably in the range of 1 to 500 m / min, more preferably 5 to 300 m / min, and further Preferably, it is within the range of 10 to 100 m / min.
- the line speed is 1 m / min or more, appropriate productivity can be secured, damage to the transparent polarizing plate protective film can be suppressed, and a polarizing plate that can withstand a durability test can be produced.
- the line speed is 500 m / min or less, the resulting adhesive is sufficiently cured, and the desired adhesiveness can be obtained.
- the thickness of the active energy ray-curable adhesive layer is not particularly limited, but is usually in the range of 0.01 to 10 ⁇ m, preferably 0.5 to 5 ⁇ m. Within range.
- the first polarizing plate A, the liquid crystal cell, and the second polarizing plate B are arranged in this order from the viewing surface side, and the polarizing plate A and the polarizing plate B are Both are polarizing plates of the present invention, and from the viewing surface side, the first polarizing plate A is composed of a polarizing plate protective film T1, a polarizer and a retardation film T2, and the second polarizing plate B is a retardation.
- polarizing plate protective film T1 and polarizing plate protective film T4 are polarizing plate protective films which consist of a structure prescribed
- a functional layer such as a hard coat layer, an antireflection layer or an antiglare layer on the viewing side of the polarizing plate protective film T1.
- the polarizing plate protective film of the present invention is excellent in water resistance, heat resistance, flatness, etc.
- the glass substrate constituting the liquid crystal cell is thinned by providing the liquid crystal display device with the polarizing plate of the present invention. As a result, a liquid crystal display device in which thinning is achieved can be obtained.
- glass substrate examples include soda lime glass, silicate glass, and the like, and preferably silicate glass, specifically, silica glass or borosilicate glass. More preferably.
- the glass constituting the glass substrate is preferably a non-alkali glass that does not substantially contain an alkali component, specifically, a glass having an alkali component content of 1000 ppm or less.
- the content of the alkali component in the glass substrate is preferably 500 ppm or less, and more preferably 300 ppm or less.
- substitution of cations occurs on the film surface, and soda blowing phenomenon tends to occur. Thereby, the density of the film surface layer tends to be lowered, and the glass substrate is easily damaged.
- the thickness of the glass substrate of the liquid crystal cell constituting the liquid crystal display device is preferably in the range of 0.4 to 0.6 mm. Such a thickness is preferable in that it can contribute to the formation of a thin liquid crystal display device.
- the glass substrate can be formed by a known method such as a float method, a down draw method, an overflow down draw method or the like.
- the overflow downdraw method is preferable because the surface of the glass substrate does not come into contact with the molded member during molding and the surface of the glass substrate to be obtained is hardly damaged.
- such a glass base material can also be obtained as a commercial item, for example, non-alkali glass AN100 (thickness 500 ⁇ m) manufactured by Asahi Glass Co., Ltd., a glass substrate EAGLE XG (r) Slim (thickness manufactured by Corning) 300 ⁇ m, 400 ⁇ m, etc.), a glass substrate (thickness 100 to 200 ⁇ m) manufactured by Nippon Electric Glass Co., Ltd., and the like.
- the polarizing plate of the present invention By using the polarizing plate of the present invention, even if the screen using the thin film glass substrate for a liquid crystal cell is a large-screen liquid crystal display device of 30 type or more, display unevenness (bend unevenness) is suppressed and the front surface is suppressed. A liquid crystal display device having excellent visibility such as contrast can be obtained.
- FIG. 3 is a schematic sectional view showing an example of the configuration of the liquid crystal display device 106 including the polarizing plate 101 of the present invention.
- a liquid crystal cell 107 is sandwiched between the retardation film 105 constituting the polarizing plate 101A and the retardation film 105 constituting the polarizing plate 101B described in FIG. Yes.
- a polarizing plate protective film 102 is disposed on the surface portion as an optical film, which is referred to as a polarizing plate protective film T ⁇ b> 1, and further below the polarizer 104.
- the phase difference film 105 is arrange
- the functional layer described above is formed on the viewing side of the polarizing plate protective film 102 that is T1.
- a polarizing plate 101B is disposed on the opposite surface of the liquid crystal cell 107, and a polarizing plate protective film 102 is disposed as an optical film from the outermost surface. In the present invention, this is referred to as a polarizing plate protective film T4. Further, a retardation film 105 is disposed under the polarizer 104 (on the liquid crystal cell side), and this is referred to as a retardation film T3.
- the polarizing plate protective film of the present invention includes the polarizing plate protective film 102 of the polarizing plate 101A (polarizing plate protective film T1) and the polarizing plate protective film 102 of the polarizing plate 101B (polarizing plate). This is a protective film T4).
- Bonding between the surface of the polarizing plate on the side of the retardation film and at least one surface of the liquid crystal cell can be performed by a known method. Depending on the case, it may be bonded via an adhesive layer or an adhesive layer.
- the mode (driving method) of the liquid crystal display device is not particularly limited, and liquid crystal display devices in various drive modes such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, and OCB can be used.
- a VA (MVA, PVA) type liquid crystal display device is preferable. Note that the direction of bonding of the polarizing plate in the VA mode liquid crystal display device can be performed with reference to JP-A-2005-234431.
- a liquid crystal display device having excellent visibility such as unevenness of the liquid crystal display device can be obtained even for a liquid crystal display device with a large screen of 30 type or more. be able to.
- the obtained polymerization solution was continuously supplied to an extruder to perform extrusion molding, and unreacted monomer and solvent were collected by the extruder to obtain styrene-acrylonitrile copolymer pellets.
- the obtained copolymer was colorless and transparent, and as a result of composition analysis by the following method, the content of styrene units was 70 mol%, and the content of acrylonitrile units was 30 mol%. Moreover, the weight average molecular weight was 200,000 as a result of the weight average molecular weight measurement by GPC (polystyrene conversion of the GPC system manufactured by Tosoh Corporation).
- the content ratio of the structural unit of the obtained copolymer (A) was measured by the following method.
- copolymer 2 a styrene-acrylonitrile copolymer having a styrene unit content of 60 mol% and an acrylonitrile unit content of 40 mol% was prepared, and a copolymer having a weight average molecular weight of 200,000 shown in Table 1 was prepared. Polymer 2 was prepared.
- copolymer 3 a copolymer having a styrene unit content of 45 mol%, an acrylonitrile unit content of 30 mol%, and an N-phenylmaleimide unit content of 25 mol% was prepared.
- copolymer 4 a copolymer having a styrene unit content of 55 mol%, an acrylonitrile unit content of 20 mol%, and an N-phenylmaleimide unit content of 25 mol% was prepared.
- Copolymer 5 a copolymer having a styrene unit content of 50 mol%, an acrylonitrile unit content of 25 mol%, and a cyclohexylmaleimide unit content of 25 mol% was prepared.
- Copolymer 6 a copolymer having a styrene unit content of 55 mol%, an acrylonitrile unit content of 25 mol%, and a benzylmaleimide unit content of 20 mol% was prepared. A copolymer 6 having a weight average molecular weight of 200,000 was prepared.
- Copolymer 7 ⁇ -methylstyrene was used in place of styrene to prepare a copolymer having an ⁇ -methylstyrene unit content of 70 mol% and an acrylonitrile unit content of 30 mol%.
- a copolymer 7 having a weight average molecular weight of 150,000 shown in Table 1 was prepared.
- copolymer 8 In the preparation of copolymer 1, a copolymer having a styrene unit content of 70 mol% and methacrylonitrile instead of acrylonitrile was used to prepare a copolymer having a methacrylonitrile unit content of 30 mol%. The described copolymer 8 having a weight average molecular weight of 200,000 was prepared.
- the polymerization solution thus obtained was dried at 240 ° C. under reduced pressure for 1 hour, and the content of N-funmaleimide units was 30 mol% and the content of styrene units was 70 mol%.
- a transparent copolymer (B) having a weight average molecular weight of 150,000 was obtained.
- Copolymer 10 was prepared as shown in Table 1, except that the mixing ratio of copolymer (A) and copolymer (B) was 30:70 in the preparation of copolymer 9. .
- ⁇ Preparation of copolymer 19> In the preparation of copolymer 1, a styrene-acrylonitrile copolymer having a styrene unit content of 90 mol% and an acrylonitrile unit content of 10 mol% was prepared, and the copolymer having a weight average molecular weight of 250,000 shown in Table 1 was prepared. Polymer 19 was prepared. ⁇ Preparation of copolymer 20> By a conventional method, a copolymer 20 that was polymethyl methacrylate having a methyl methacrylate unit content of 95 mol% and a methacrylic acid unit content of 5 mol% was prepared. The weight average molecular weight was 200,000 and used alone as described in Table 1.
- the content (mass%) of the unreacted monomer with respect to the total mass of the copolymer (A) contained in the sample solution is measured by GC / MS.
- the measuring apparatus and measuring conditions of GC / MS are as follows.
- Stripping aid (Compound 1) 1-1: ELECUT S-412-2 (manufactured by Takemoto Yushi Co., Ltd.): sodium dodecylbenzenesulfonate 1-2: Epan 750 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): nonionic surfactant 1-3 : Stearyl alcohol (3) Rubber particles (Compound 2) 2-1: Tufprene 126S (Asahi Kasei Chemicals Corporation) styrene-butadiene copolymer 2-2: TR2003 (JSR Corporation) styrene-butadiene copolymer 2-3: The following particles 1 2-4: Particle 2 below ⁇ Particle 1: Acrylic particles synthesized by the following method> (Acrylic particles C1) A reactor with a reflux condenser with an internal volume of 60 liters is charged with 38.2 liters of ion-exchanged water and 111.6 g of sodium diocty
- n-OM n-octyl mercaptan
- the polymer latex thus obtained was poured into a 3% by weight sodium sulfate aqueous solution, salted out and coagulated, then dehydrated and washed repeatedly, then dried and acrylic having a three-layer structure. Particles were obtained.
- the average particle size determined by the absorbance method was 100 nm.
- ⁇ Particle 2 Elastic organic fine particles synthesized by the following method> (Elastic organic fine particles (B1)) In a pressure-resistant reaction vessel equipped with a stirrer, 70 parts of deionized water, 0.5 part of sodium pyrophosphate, 0.2 part of potassium oleate, 0.005 part of ferrous sulfate, 0.2 part of dextrose, p-menthane A mixture comprising 0.1 part of hydroperoxide and 28 parts of 1,3-butadiene was added, the temperature was raised to 65 ° C., and a polymerization reaction was carried out for 2 hours.
- the internal temperature was raised to 80 ° C. and polymerization was continued for 2 hours.
- the mixture was passed through a 300 mesh wire net to obtain an emulsion polymerization liquid of elastic organic fine particles.
- the obtained emulsion polymerization liquid of elastic organic fine particles was salted out and solidified with calcium chloride, washed with water and dried to obtain powdery elastic organic fine particles.
- the volume average particle diameter of the elastic organic fine particles was 0.260 ⁇ m.
- the peeled film-like product was dried at a drying temperature of 135 ° C. while evaporating the solvent at 35 ° C. and stretching it 1.25 times in the width direction (TD direction) by tenter stretching.
- the residual solvent amount at the start of stretching by zone stretching was 20.0%, and the residual solvent amount at the start of stretching by tenter was 8.0%.
- the obtained film was slit to a width of 1.5 m, a knurling process having a width of 10 mm and a height of 5 ⁇ m was applied to both ends of the film, and then wound around a core to prepare a polarizing plate protective film 101.
- the produced protective film 101 had a thickness of 40 ⁇ m and a winding length of 4000 m.
- the obtained mixture was melt-kneaded at 235 ° C. with a twin-screw extruder and extruded into a strand shape.
- the resin composition extruded in a strand form was cooled with water and then cut to obtain pellets.
- the obtained pellets were put into a single screw extruder and melt kneaded at 250 ° C. in a nitrogen atmosphere. Then, it extruded from the die
- polarizing plate protective films 127 and 128 In the production of the polarizing plate protective film 126, a polarizing plate protective film 127 having a thickness of 40 ⁇ m was obtained in the same manner except that the copolymer 9 was used. Similarly, a polarizing plate protective film 128 was obtained using the copolymer 20.
- Heat resistance Heat resistance is evaluated by the glass transition temperature Tg (° C) of the polarizing plate protective film, and the higher the Tg (° C), the better the heat resistance.
- the glass transition temperature Tg (° C.) is measured using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Inc. according to JIS K-7121.
- sample film About 10 mg of sample film is set, and the temperature is raised from room temperature to 250 ° C. at 20 ° C./min under a nitrogen flow rate of 50 ml / min. The temperature was lowered to 30 ° C. and held for 10 minutes (2nd scan), further raised to 250 ° C. at 20 ° C./min (3rd scan), a DSC curve was created, and the glass transition temperature was obtained from the obtained 3rd scan DSC curve Obtain Tg.
- Tg glass transition temperature
- the glass transition temperature is 120 ° C. or higher.
- ⁇ The glass transition temperature is in the range of 110 ° C. or higher and lower than 120 ° C.
- ⁇ The glass transition temperature is in the range of 100 ° C. or higher and lower than 110 ° C.
- ⁇ Glass transition temperature is less than 100 ° C.
- Haze Haze is a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K-7136. Measure with
- Yellow index (YI) The yellow index (YI) is obtained by the method described in JIS K-7105-6.3. As a specific method for measuring the yellow index value, the color tristimulus values X, Y, and Z are obtained using a spectrophotometer U-3200 manufactured by Hitachi, Ltd. and the attached saturation calculation program, etc. The yellow index value is obtained.
- the polarizing plate protective films 101 to 109 and 113 to 127 of the present invention are excellent in heat resistance, haze, yellow index (YI), and bending resistance. Moreover, the polarizing plate protective film 130 to which the rubber particles (Compound 2) were not added had slightly inferior bending resistance.
- the polarizing plate protective films 126 and 127 produced by the melt casting method have a slightly high yellow index (YI) value, and coloring is observed.
- the solution casting method is used. It turns out that it is preferable to employ.
- the polarizing plate protective films 110 to 112 which are comparative examples, have a high mixing ratio of the copolymer (B) or use only the copolymer (B), so that the bending resistance is inferior and is difficult to use practically. It is. Moreover, the polarizing plate protective film 128 using polymethylmethacrylate alone was inferior in heat resistance and bending resistance.
- composition of dope for core layer Cellulose acetate (total substitution degree 2.45, acetyl group substitution degree 2.45, weight average molecular weight 180,000) 100 parts by mass Compound C (retardation increasing agent) 3 parts by mass Compound D (terephthalic acid / succinic acid / ethanediol / Propanediol (80/20/50/50 molar ratio) condensate having both ends sealed with acetyl ester groups) 10 parts by weight Dichloromethane 406 parts by weight Methanol 61 parts by weight (Composition of dope for skin B layer) Cellulose acetate (total substitution degree 2.93, acetyl group substitution degree 2.93, weight average molecular weight 280,000) 100 parts by mass Compound E (terephthalic acid / succinic acid / ethylene glycol copolymer (50/50/100 molar ratio) , Molecular weight 2000, retardation developing agent) 4 parts by mass Aerosil R972
- the obtained core layer dope, skin A layer dope and skin B layer dope were co-cast from a casting die on a traveling casting band (simultaneous multilayer casting).
- the co-casting was performed so that the dope for the skin B layer was in contact with the casting band.
- the cast film was peeled off from the cast band and then dried with a tenter to obtain a film-like material.
- the residual solvent amount of the film-like material immediately after peeling off was about 30% by mass.
- the film-like material was stretched in the width direction with a tenter at a stretching ratio of 30% and then relaxed at 140 ° C. for 60 seconds to have a three-layer structure of skin B layer / core layer / skin A layer, film thickness of 40 ⁇ m A retardation film A was obtained.
- Phase difference film B The following components are put into a mixing tank and stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 ⁇ m and a sintered metal filter having an average pore size of 10 ⁇ m. Layer dope and skin A layer dope were prepared respectively.
- Three layers of skin B layer / core layer / skin A layer were prepared in the same manner as in the preparation of the retardation film A except that the obtained core layer dope, skin A layer dope, and skin B layer dope were used.
- a retardation film B having a structure and a film thickness of 40 ⁇ m was obtained.
- Phase difference film C The following components were stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to obtain a fine particle dispersion 1.
- Fine particle dispersion 1 Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11 parts by mass Ethanol 89 parts by mass The above-prepared fine particle dispersion 1 was slowly added to a dissolution tank containing methylene chloride while stirring sufficiently. The resulting solution was dispersed with an attritor so that the secondary particles had a predetermined particle size, and then filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1 did.
- Fine particle dispersion 1 5 parts by mass
- a main dope having the following composition was prepared. First, after adding methylene chloride and ethanol to the pressure dissolution tank, the cellulose acetate, sugar ester compound, polycondensation ester, retardation increasing agent and fine particle additive solution 1 having an acetyl group substitution degree of 2.40 are added with stirring. did. This was heated and dissolved completely with stirring. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. The main dope was prepared by filtration using 244.
- the obtained film was peeled from the stainless steel belt support with a peeling tension of 130 N / m.
- the film-like material obtained by peeling was stretched 30% in the width direction using a tenter while applying heat at 150 ° C.
- the residual solvent at the start of stretching was 15%.
- drying was terminated while the drying zone was conveyed by a number of rolls.
- the drying temperature was 130 ° C. and the transport tension was 100 N / m.
- a retardation film C having a dry film thickness of 35 ⁇ m was obtained.
- 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate 45 parts by mass Epolide GT-301 (alicyclic epoxy resin manufactured by Daicel Chemical Industries) 40 parts by mass 1,4-butanediol diglycidyl ether 15 parts by mass Triarylsulfonium hexafluorophosphate 2.3 parts by mass 9,10-dibutoxyanthracene 0.1 parts by mass 1,4-diethoxynaphthalene 2.0 parts by mass 4)
- Preparation of polarizing plate A phase difference film C was prepared, and its surface was subjected to corona discharge treatment.
- the corona discharge treatment was performed at a corona output intensity of 2.0 kW and a line speed of 18 m / min.
- the prepared water paste or active energy ray-curable adhesive liquid is applied to the corona discharge-treated surface of the retardation film C with a bar coater so that the film thickness after curing is about 3 ⁇ m.
- a paste layer or an active energy ray-curable adhesive layer was formed.
- the prepared polarizer having a thickness of 15 ⁇ m was bonded to the obtained water paste layer or active energy ray-curable adhesive layer.
- a polarizing plate protective film 101 was prepared as a polarizing plate protective film, and the surface of the polarizing plate protective film 101 was subjected to corona discharge treatment.
- the conditions for the corona discharge treatment were a corona output intensity of 2.0 kW and a line speed of 18 m / min.
- the prepared water paste or active energy ray-curable adhesive liquid is applied to the corona discharge-treated surface of the polarizing plate protective film 101 with a bar coater so that the film thickness after curing is about 3 ⁇ m.
- a water paste layer or an active energy ray-curable adhesive layer was formed.
- a polarizer bonded to one side of the retardation film C is laminated on the water paste layer or active energy ray-curable adhesive layer of the polarizing plate protective film, and the polarizing plate protective film 101 / water paste layer / polarizer.
- a polarizing plate 101P which is a laminate of / water glue layer / retardation film C was produced. The obtained polarizing plate 101P was dried at 80 ° C.
- the laminate was performed so that the slow axis of the retardation film C and the absorption axis of the polarizer were orthogonal to each other.
- polarizing plate 101U which is a laminate of polarizing plate protective film 101 / active energy ray-curable adhesive layer / polarizer / active energy ray-curable adhesive layer / retardation film C was obtained.
- the polarizing plate 101U uses an ultraviolet irradiation device with a belt conveyor (the lamp uses a D bulb manufactured by Fusion UV Systems) from the phase difference film C side so that the accumulated light amount is 750 mJ / cm 2. Irradiation was performed to cure the active energy ray-curable adhesive layer.
- the prepared liquid crystal display panel was placed to obtain the liquid crystal display device 101.
- the absorption axis of the polarizing plate of the attached liquid crystal display panel was set to be in the same direction as the absorption axis of the polarizing plate attached in advance.
- liquid crystal display devices 102 to 130 were produced using polarizing plates 102U to 130U.
- the bend unevenness of the obtained liquid crystal display device was measured by the following method.
- the polarizing plate protective films 101 to 109 and 113 to 127, 129, and 130 of the present invention are compared with the comparative example with either a water paste or an active energy ray-curable adhesive. It turns out that it is excellent in adhesiveness. Moreover, it is clear that the polarizing plate having a polarizer sandwiched between the polarizing plate protective film and the cellulose ester phase difference film of the present invention is excellent in bend unevenness when it is provided in a liquid crystal display device.
- the composition of the polarizing plate protective film of the present invention has high water resistance and suppresses the occurrence of bend unevenness in the liquid crystal display device, and water glue and active energy ray-curable adhesive It was found that an excellent polarizing plate protective film having good adhesion to the polarizer can be obtained by combining with any of the above.
- the polarizing plate protective film of the present invention has high water resistance and heat resistance, suppresses the occurrence of bend unevenness in the liquid crystal display device, and can be used as a polarizer in combination with either water glue or an active energy ray-curable adhesive. Therefore, it is suitably used for polarizing plates and liquid crystal display devices.
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Abstract
Description
本発明の偏光板保護フィルムは、熱可塑性樹脂の主成分として、芳香族ビニルモノマーと不飽和ニトリルモノマーとを重合して得られる共重合体(A)と、イミド環構造を有する共重合体(B)とを、質量比率でA:B=100:0~50:50の範囲内で含有することを特徴とし、かかる構成によって、高い耐水性及び耐熱性を有して液晶表示装置の表示ムラ(ベンドムラ又は)の発生を抑制し、かつ水糊及び活性エネルギー線硬化型接着剤のどちらとの組み合わせでも偏光子との良好な接着性を有する偏光板保護フィルムを得ることができる。
<共重合体>
本発明の偏光板保護フィルムは、熱可塑性樹脂の主成分として、芳香族ビニルモノマーと不飽和ニトリルモノマーとを重合して得られる共重合体(A)と、イミド環構造を有する共重合体(B)とを、質量比率でA:B=100:0~50:50の範囲内で含有することが特徴である。なお、共重合体を構成するモノマーのことを「~単位」という。
〔芳香族ビニルモノマー;成分(a)〕
芳香族ビニルモノマーは、共重合体(A)の耐水性を高める機能を有している。芳香族ビニルモノマーは、スチレン系化合物であることが好ましい。スチレン系化合物の具体例には、スチレン;α-メチルスチレン、β-メチルスチレン、p-メチルスチレンなどのアルキル置換スチレン類;4-クロロスチレン、4-ブロモスチレンなどのハロゲン置換スチレン類;p-ヒドロキシスチレン、α-メチル-p-ヒドロキシスチレン、2-メチル-4-ヒドロキシスチレン、3,4-ジヒドロキシスチレンなどのヒドロキシスチレン類;ビニルベンジルアルコール類;p-メトキシスチレン、p-tert-ブトキシスチレン、m-tert-ブトキシスチレンなどのアルコキシ置換スチレン類;3-ビニル安息香酸、4-ビニル安息香酸などのビニル安息香酸類;4-ビニルベンジルアセテート;4-アセトキシスチレン;2-ブチルアミドスチレン、4-メチルアミドスチレン、p-スルホンアミドスチレンなどのアミドスチレン類;3-アミノスチレン、4-アミノスチレン、2-イソプロペニルアニリン、ビニルベンジルジメチルアミンなどのアミノスチレン類;3-ニトロスチレン、4-ニトロスチレンなどのニトロスチレン類;3-シアノスチレン、4-シアノスチレンなどのシアノスチレン類;ビニルフェニルアセトニトリル;フェニルスチレンなどのアリールスチレン類、インデン類などが含まれる。
不飽和ニトリルモノマーの具体例としては、アクリロニトリル、メタクリロニトリル、エタクリロニトリル、フマロニトリル等のシアン化ビニル化合物が挙げられ、中でもアクリロニトリルが好ましい。アクリロニトリルモノマーはCN基を有するため極性が高く、親水性基を有する水糊との相互作用により接着性がよい。
また、本発明に係るス共重合体(A)は、成分(a)及び/又は成分(b)と共重合可能な他のモノマーを含んでも良い。そのような共重合可能なモノマー(c)としては、メチル(メタ)アクリレート、エチル(メタ)アクリレート、プロピル(メタ)アクリレート、ブチル(メタ)アクリレート、2-エチル(メタ)アクリレート、2-エチルヘキシルメタアクリレート等のアルキル(メタ)アクリレート;アクリル酸、メタクリル酸などの(メタ)アクリル酸;無水マレイン酸等のα、β―不飽和カルボン酸;N-フェニルマレイミド、N-メチルマレイミド、N-シクロヘキシルマレイミド等のマレイミド;グリシジルメタクリレート等のグリシジル基含有モノマーが挙げられる。これらの中でも、メチルアクリレートのようなアルキル(メタ)アクリレート等が好ましい。他のモノマー(c)は一種類で用いてもよいし、二種類以上を併用してもよい。
本発明に係る共重合体(A)は、芳香族ビニルモノマー単位を50~75モル%の範囲内と不飽和ニトリルモノマー単位を25~50モル%の範囲内の比率で共重合することが、耐水性と水糊との接着性のバランスをとり、イミド環構造を有する共重合体(B)との相溶性の点で好ましい。また、その他のモノマー単位を使用する場合は0~25質量%の範囲内の比率で共重合されていることが、好ましい。
本発明に係る共重合体を得る方法としては、例えば、完全撹拌混合槽に、モノマー、開始剤、溶媒等を連続的にフィードし、連続的に反応槽から抜き出し、熱時、脱揮系で揮発分を除去する方法が挙げられる。脱揮系でのポリマー滞留は極力少なくすることが好ましい。
本発明に係る共重合体に含まれる未反応モノマーの含有量は、以下の方法で測定できる。
カラム:J&W社製 DB-624(0.25mmi.d.×30ml)
オーブンプログラム:40℃(3min)-20℃/min-230℃(8min)
Inj:160℃
AUX:250℃ 本発明に係る共重合体の重量平均分子量(Mw)としては、スチレン換算分子量で好ましくは1000~200万の範囲内、より好ましくは5000~100万の範囲内、さらに好ましくは1万~50万の範囲内、特に好ましくは5万~50万の範囲内である。
重量平均分子量はゲル浸透クロマトグラフィー(東ソー社製 HLC8220GPC)、カラム(東ソー社製 TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL 直列)を用いて測定する。試料 20mg±0.5mgをテトラヒドロフラン 10mlに溶解し、0.45mmのフィルターで濾過した。この溶液をカラム温度40℃に100ml注入し、検出器RI温度 40℃で測定しスチレン換算した値を用いる。
本発明の偏光板保護フィルムは、フィルムの耐熱性向上の観点から、構造中にイミド環構造を有する共重合体(B)を、前記共重合体(A)とともに含有する。
環構造がマレイミド構造であるアクリル樹脂は、例えば特開昭57-153008号公報、特開2007-31537号公報に記載の方法により製造できる。
本発明に係る共重合体(A)及び(B)は、本発明の効果を阻害しない範囲で、その他の樹脂を併用することができる。その他の樹脂としては、他のスチレン系樹脂や(メタ)アクリル樹脂を好ましく用いることができる。
本発明の偏光板保護フィルムは、芳香族ビニルモノマーと不飽和ニトリルモノマーとを重合して得られる共重合体(A)とイミド環構造を有する共重合体(B)とを、質量比率でA:B=100:0~50:50の範囲内で含有することが特徴であり、当該範囲内であれば、高い耐水性及び耐熱性を有して液晶表示装置の表示ムラ(ベンドムラ)の発生を抑制し、かつ水糊及び活性エネルギー線硬化型接着剤のどちらとの組み合わせでも偏光子との良好な接着性を有する偏光板保護フィルムを得ることができる。
本発明の偏光板保護フィルムは、必要に応じて剥離助剤、耐電防止剤、酸化防止剤、紫外線吸収剤、滑り性を付与するための微粒子(マット剤)、靱性を高めるための衝撃補強材などの各種添加剤をさらに含むことができる。
本発明に係る芳香族ビニルモノマーと不飽和ニトリルモノマーとの共重合体を含む膜状物は、金属支持体との密着性が高いことから、金属支持体から剥離しやすくし、剥離時の伸びを抑制して得られるフィルムの厚さ均一にするために、剥離助剤又は帯電防止剤を含有させることが好ましい。
イコサン-1-オール、ヘネイコサン-1-オール 、及びドコサン-1-オール等が挙げられ、オクタデカン-1-オール(ステアリルアルコール)が好ましい。
また、剥離助剤として非イオン性界面活性剤を用いることも有用であり、例えば、ポリオキシエチレンポリオキシプロピレングリコールなどのポリオキシアルキレングリコール、ポリオキシエチレンスチレン化フェニルエーテルなどのポリオキシアルキレンスチレン化フェニルエーテル、ポリオキシエチレントリデシルエーテル及びポリオキシエチレンラウリルエーテルなどのポリオキシアルキレングリコール、ポリオキシエチレンソルビタンモノココエート、ポリオキシエチレンソルビタンモノステアレート及びポリオキシエチレン硬化ひまし油などのポリオキシアルキレン脂肪酸エステルなどの非イオン性界面活性剤が挙げられ、これらは単独で使用してもよく、2種以上を併用してもよい。またこれらの市販品としては、第一工業製薬(株)製エパン等が挙げられる。
本発明では、酸化防止剤としては、通常知られているものを使用することができる。特に、ラクトン系、イオウ系、フェノール系、二重結合系、ヒンダードアミン系、リン系の各化合物を好ましく用いることができる。
本発明に係る偏光板保護フィルムは、紫外線吸収剤を含有することが好ましく、適用可能な紫外線吸収剤としては、ベンゾトリアゾール系、2-ヒドロキシベンゾフェノン系又はサリチル酸フェニルエステル系、トリアジン系等の紫外線吸収剤が挙げられる。例えば、2-(5-メチル-2-ヒドロキシフェニル)ベンゾトリアゾール、2-[2-ヒドロキシ-3,5-ビス(α,α-ジメチルベンジル)フェニル]-2H-ベンゾトリアゾール、2-(3,5-ジ-t-ブチル-2-ヒドロキシフェニル)ベンゾトリアゾール等のトリアゾール類、2-ヒドロキシ-4-メトキシベンゾフェノン、2-ヒドロキシ-4-オクトキシベンゾフェノン、2,2′-ジヒドロキシ-4-メトキシベンゾフェノン等のベンゾフェノン類を例示することができる。
本発明では、偏光板保護フィルムに滑り性を付与するため、マット剤を添加することが好ましい。
本発明に係る偏光板保護フィルムには、耐衝撃性を高めるために、衝撃補強材として、コア・シェルタイプのアクリル微粒子、スチレン-共役ジエン系化合物又はブチルアクリレート化合物の少なくとも一種を含有することが好ましい。
市販品としては、例えば、メタブレンC-140A、C-215A(以上、三菱レイヨン(株)製)、タフプレン126、アサフレックス800、アサフレックス825(以上、旭化成ケミカルズ(株)製)、TR2000 、TR2250(以上、JSR(株)製)などが挙げられる。
本発明の偏光板保護フィルムの製造方法としては、通常のインフレーション法、T-ダイ法、カレンダー法、切削法、流延法、エマルジョン法、ホットプレス法等の製造法が使用できるが、着色抑制、異物欠点の抑制、ダイラインなどの光学欠点の抑制などの観点から、製膜方法は溶液流延製膜法と溶融流延製膜法が選択でき、特に溶液流延製膜法であることが、樹脂の分布状態を制御してパネルベンドを抑制する効果に加えて、均一で平滑な表面を得ることができ、さらにヘイズ及びイエローインデックス(YI)を低減する観点から好ましい。
以下、本発明の偏光板保護フィルムを溶液流延法で製造する製造例について説明する。
樹脂に対する良溶媒を主とする有機溶媒に、溶解釜中で当該樹脂、場合によって、その他の化合物を撹拌しながら溶解しドープを形成する工程、又は当該樹脂溶液に、前記その他の化合物溶液を混合して主溶解液であるドープを形成する工程である。
(2-1)ドープの流延
ドープを、送液ポンプ(例えば、加圧型定量ギヤポンプ)を通して加圧ダイ30に送液し、無限に移送する無端の金属支持体31、例えば、ステンレスベルト、あるいは回転する金属ドラム等の金属支持体上の流延位置に、加圧ダイスリットからドープを流延する工程である。
ウェブ(流延用支持体上にドープを流延し、形成されたドープ膜をウェブという。)を流延用支持体上で加熱し、溶媒を蒸発させる工程である。
金属支持体上で溶媒が蒸発したウェブを、剥離位置で剥離する工程である。剥離されたウェブはフィルムとして次工程に送られる。
残留溶媒量(%)=(ウェブの加熱処理前質量-ウェブの加熱処理後質量)/(ウェブの加熱処理後質量)×100
なお、残留溶媒量を測定する際の加熱処理とは、115℃で1時間の加熱処理を行うことを表す。
乾燥工程は予備乾燥工程、本乾燥工程に分けて行うこともできる。
金属支持体から剥離して得られたウェブを乾燥させる。ウェブの乾燥は、ウェブを、上下に配置した多数のローラーにより搬送しながら乾燥させてもよいし、テンター乾燥機のようにウェブの両端部をクリップで固定して搬送しながら乾燥させてもよい。
本発明の偏光板保護フィルムは、延伸処理することでフィルム内の分子の配向を制御することができ、平面性を向上したり、強靭性を得たりすることができる。
・流延方向に延伸→幅手方向に延伸→流延方向に延伸→流延方向に延伸
・幅手方向に延伸→幅手方向に延伸→流延方向に延伸→流延方向に延伸
また、同時二軸延伸には、一方向に延伸し、もう一方を、張力を緩和して収縮する場合も含まれる。
(式(E)において、d1は延伸後の樹脂フィルムの前記延伸方向の幅寸法であり、d2は延伸前の樹脂フィルムの前記延伸方向の幅寸法であり、tは延伸に要する時間(min)である。)
本発明の偏光板保護フィルムの面内リターデーション値Ro、及び厚さ方向のリターデーション値Rtは自動複屈折率計アクソスキャン(Axo Scan Mueller Matrix Polarimeter:アクソメトリックス社製)を用いて、23℃・55%RHの環境下、590nmの波長において、三次元屈折率測定を行い、得られた屈折率nx、ny、nzから算出することができる。
式(ii):Rt={(nx+ny)/2-nz}×d(nm)
〔式(i)及び式(ii)において、nxは、フィルムの面内方向において屈折率が最大になる方向xにおける屈折率を表す。nyは、フィルムの面内方向において、前記方向xと直交する方向yにおける屈折率を表す。nzは、フィルムの厚さ方向zにおける屈折率を表す。dは、フィルムの厚さ(nm)を表す。〕
〈ナーリング加工〉
所定の熱処理又は冷却処理の後、巻取り前にスリッターを設けて端部を切り落とすことが良好な巻姿を得るため好ましい。更に、幅手両端部にはナーリング加工をすることが好ましい。
ウェブ中の残留溶媒量が2質量%以下となってからフィルムとして巻取る工程であり、残留溶媒量を0.4質量%以下にすることにより寸法安定性の良好なフィルムを得ることができる。
本発明の偏光板保護フィルムは、溶融流延法によって製膜することもできる。溶融流延法は、本発明に係る共重合体及びその他の化合物を含む組成物を、流動性を示す温度まで加熱溶融し、その後、流動性の溶融物を流延することをいう。
〈ヘイズ〉
本発明の偏光板保護フィルムは、ヘイズが1.0%以下であることが好ましく、0.5%以下であることがより好ましい。ヘイズを1.0%以下とすることにより、フィルムの透明性がより高くなり、光学用途のフィルムとしてより用いやすくなるという利点がある。
本発明の偏光板保護フィルムは、YIが1.0以下であることが好ましく、0.5以下であることがより好ましい。YIを1.0以下とすることにより、フィルムの透明性がより高くなり、光学用途のフィルムとしてより用いやすくなるという利点がある。特に本発明の偏光板保護フィルムを溶液流延法で製造することは、YIを低減する観点から好ましい製造方法である。
〈全光線透過率〉
偏光板保護フィルムの全光線透過率は、好ましくは90%以上であり、より好ましくは93%以上である。全光線透過率は、JIS7573「プラスチック‐全光線透過率及び全光線反射率の求め方」に従って測定することができる。
本発明の偏光板保護フィルムは、25℃、相対湿度55%における平衡含水率が3%以下であることが好ましく、2%以下であることがより好ましい。平衡含水率を3%以下とすることにより、湿度変化に対応しやすく、光学特性や寸法がより変化しにくく好ましい。
本発明の偏光板保護フィルムは、長尺であることが好ましく、具体的には、100~10000m程度の長さであることが好ましく、ロール状に巻き取られる。また、本発明の偏光板保護フィルムの幅は1m以上であることが好ましく、更に好ましくは1.4m以上であり、特に1.4~4mであることが好ましい。
偏光板保護フィルムの40℃90%RHにおける透湿度は、300g/m2・day以下であることが好ましく、200g/m2・day以下であることがより好ましく、10~100g/m2・dayの範囲が、ベンドムラを抑制する上で特に好ましい。高温高湿環境下において、透過した水分による偏光子の寸法変化を抑制するためである。透湿度は、JIS Z 0208に記載の方法に準拠して40℃90%RHの条件にて測定される。
偏光板保護フィルムの23℃55%RH下における引き裂き強度は、15mN以上であることが好ましく、20mN以上であることがより好ましく、30mN以上であることがさらに好ましい。引き裂き強度の上限は、例えば50mN程度である。
本発明の偏光板保護フィルムは、偏光子に対して、ポリビニルアルコール系接着剤又は活性エネルギー線硬化型接着剤のいずれを用いても貼合できることが特徴である。
本発明の偏光板の主たる構成要素である偏光子は、一定方向の偏波面の光だけを通す素子であり、現在知られている代表的な偏光子は、ポリビニルアルコール系偏光フィルムである。ポリビニルアルコール系偏光フィルムには、ポリビニルアルコール系フィルムにヨウ素を染色させたものと、二色性染料を染色させたものとがある。
また、本発明の偏光板は薄膜とすることが好ましく、偏光子の厚さは2~15μmの範囲内であることが、偏光板の強度と薄膜化を両立する観点から特に好ましい。
〔水糊を用いた偏光板の作製〕
本発明の偏光板は一般的な方法で作製することができる。本発明の偏光板保護フィルムの偏光子側をコロナ処理、プラズマ処理又はエキシマ光処理等の表面処理を行い、ヨウ素溶液中に浸漬延伸して作製した前記偏光子の少なくとも一方の面に、完全ケン化型ポリビニルアルコール水溶液(水糊)を用いて貼り合わせることができる。
偏光子の一方の面には、位相差フィルムを配置することが、VA型液晶補表示装置に具備され視野角拡大やコントラスト向上等の視認性の改善のために好ましい。
式(b) 0≦Y≦1.5
(式中、Xはアセチル基の置換度を示し、Yはプロピオニル基又はブチリル基、若しくはそれらの混合物の置換度を示す)
セルロースエステルの重量平均分子量(Mw)は、フィルム強度と製膜時の適正粘度との観点から、7.5万以上であることが好ましく、10万~100万であることがより好
ましく、10万~50万であることが特に好ましい。
本発明の偏光板においては、上記説明した本発明の偏光板保護フィルムと偏光子の少なくとも一方の面とが、活性エネルギー線硬化型接着剤により貼合されていることが好ましい態様である。その場合、同様に上記位相差フィルムと偏光子とが、活性エネルギー線硬化型接着剤により貼合されていることが好ましい。さらに、同一種類の活性エネルギー線硬化型接着剤により貼合されていることが好ましい。
偏光板の製造に適用可能な活性エネルギー線硬化型接着剤組成物としては、光ラジカル重合を利用した光ラジカル重合型組成物、光カチオン重合を利用した光カチオン重合型組成物、並びに光ラジカル重合及び光カチオン重合を併用したハイブリッド型組成物が知られている。
1)偏光子と本発明の偏光板保護フィルムとの接着面のうち、少なくとも一方に、下記の活性エネルギー線硬化型接着剤を塗布する接着剤塗布工程と、
2)接着剤層を介して偏光子と偏光板保護フィルムとを接着し、貼り合わせる貼合工程と、
3)接着剤層を介して偏光子と偏光板保護フィルムとが接着された状態で接着剤層を硬化させる硬化工程、
を挙げることができる。また、偏光板保護フィルムの偏光子を接着する面に対し、易接着処理する下記の前処理工程を有していてもよい。
前処理工程では、偏光子と接着する偏光板保護フィルムの表面に易接着処理を施す工程である。図2に例示したように、偏光子104の両面にそれぞれ偏光板保護フィルム102及び位相差フィルム105を、活性エネルギー線硬化型接着剤103A、103Bを介して接着する場合には、それぞれの偏光板保護フィルム102及び位相差フィルム105の接着面に対し、易接着処理が施される。
接着剤塗布工程では、偏光子と偏光板保護フィルムとの接着面のうち少なくとも一方の面側に、前記活性エネルギー線硬化型接着剤が塗布される。偏光子又は偏光板保護フィルムの表面に直接、活性エネルギー線硬化型接着剤を塗布する場合、その塗布方法に特別な限定はない。例えば、ドクターブレード、ワイヤーバー、ダイコーター、カンマコーター、グラビアコーター等、種々の湿式塗布方式が利用できる。また、偏光子と偏光板保護フィルムの間に、活性エネルギー線硬化型接着剤を流延させたのち、ローラー等で加圧して均一に押し広げる方法も利用できる。
上記の方法により活性エネルギー線硬化型接着剤を塗布した後は、貼合工程で処理される。この貼合工程では、例えば、先の塗布工程で偏光子の表面に活性エネルギー線硬化型接着剤を塗布した場合、そこに偏光板保護フィルムが重ね合わされる。先の塗布工程で偏光板保護フィルムの表面に活性エネルギー線硬化型接着剤を塗布した場合は、そこに偏光子が重ね合わされる。また、偏光子と偏光板保護フィルムの間に活性エネルギー線硬化型接着剤を流延させた場合は、その状態で偏光子と偏光板保護フィルムとが重ね合わされる。偏光子の両面に偏光板保護フィルム及び位相差フィルムを接着する場合であって、両面とも活性エネルギー線硬化型接着剤を用いる場合は、偏光子の両面にそれぞれ、活性エネルギー線硬化型接着剤を介して偏光板保護フィルム及び位相差フィルムが重ね合わされる。そして通常は、この状態で両面(偏光子の片面に偏光板保護フィルムを重ね合わせた場合は、偏光子側と偏光板保護フィルム側、また偏光子の両面に偏光板保護フィルム及び位相差フィルムを重ね合わせた場合は、その両面の偏光板保護フィルム及び位相差フィルム側)からローラー等で挟んで加圧することになる。ローラーの材質は、金属やゴム等を用いることが可能である。両面に配置されるローラーは、同じ材質であってもよいし、異なる材質であってもよい。
硬化工程では、未硬化の活性エネルギー線硬化型接着剤に活性エネルギー線を照射して、カチオン重合性化合物(例えば、エポキシ化合物やオキセタン化合物)やラジカル重合性化合物(例えば、アクリレート系化合物、アクリルアミド系化合物等)を含む活性エネルギー線硬化型樹脂層を硬化させ、活性エネルギー線硬化型接着剤を介して重ね合わせた偏光子と偏光板保護フィルム、又は偏光子と位相差フィルムとを接着させる。偏光子の片面に偏光板保護フィルムを貼合する場合、活性エネルギー線は、偏光子側又は偏光板保護フィルム側のいずれから照射してもよい。また、偏光子の両面に偏光板保護フィルム及び位相差フィルムを貼合する場合、偏光子の両面にそれぞれ活性エネルギー線硬化型接着剤を介して偏光板保護フィルム及び位相差フィルムを重ね合わせた状態で、活性エネルギー線を照射し、両面の活性エネルギー線硬化型接着剤を同時に硬化させるのが有利である。
本発明の液晶表示装置は、視認面側より、少なくとも第1の偏光板A、液晶セル、及び第2の偏光板Bを、この順序で配置し、前記偏光板A及び前記偏光板Bが、いずれも本発明の偏光板であり、視認面側より、前記第1の偏光板Aは偏光板保護フィルムT1、偏光子及び位相差フィルムT2から構成され、前記第2の偏光板Bは位相差フィルムT3、偏光子及び偏光板保護フィルムT4から構成されており、偏光板保護フィルムT1及び偏光板保護フィルムT4が、本発明で規定する構成からなる偏光板保護フィルムであることが好ましい。
EAGLE XG(r) Slim(厚さ300μm、400μm等)、日本電気硝子社製のガラス基材(厚さ100~200μm)等を挙げることができる。
図3に示す構成において、液晶セル107上の偏光板101Aでは、光学フィルムとして、表面部に偏光板保護フィルム102を配置し、これを偏光板保護フィルムT1と称し、更に偏光子104の下部には、位相差フィルム105が配置されており、これを位相差フィルムT2と称す。
なお、VAモード型液晶表示装置における上記偏光板の貼合の向きは、特開2005-234431号公報を参照して行うことができる。
(1)共重合体の合成及びブレンド
<共重合体1の調製>
〈共重合体(A)〉
(スチレン-アクリロニトリル共重合体)
撹拌機付き完全混合型連続反応機に、所定の配合比のスチレンとアクリロニトリルとからなるモノマー混合物を溶媒であるエチルベンゼンに混合したものを一定速度で連続的に添加しつつ、反応率を一定に保ち、150℃、滞留時間2時間で重合反応を行った。
共重合体1の調製において、スチレン単位の含有量が60モル%、アクリロニトリル単位の含有量が40モル%のスチレン-アクリロニトリル共重合体を調製し、表1に記載の重量平均分子量20万の共重合体2を調製した。
共重合体1の調製において、スチレン単位の含有量が45モル%、アクリロニトリル単位の含有量が30モル%、N-フェニルマレイミド単位の含有量が25モル%の共重合体を調製し、表1に記載の重量平均分子量20万の共重合体3を調製した。
共重合体3の調製において、スチレン単位の含有量が55モル%、アクリロニトリル単位の含有量が20モル%、N-フェニルマレイミド単位の含有量が25モル%の共重合体を調製し、表1に記載の重量平均分子量20万の共重合体4を調製した。
共重合体3の調製において、スチレン単位の含有量が50モル%、アクリロニトリル単位の含有量が25モル%、シクロヘキシルマレイミド単位の含有量が25モル%の共重合体を調製し、表1に記載の重量平均分子量20万の共重合体5を調製した。
共重合体3の調製において、スチレン単位の含有量が55モル%、アクリロニトリル単位の含有量が25モル%、ベンジルマレイミド単位の含有量が20モル%の共重合体を調製し、表1に記載の重量平均分子量20万の共重合体6を調製した。
共重合体1の調製において、スチレンの代わりにα-メチルスチレンを用いて、α-メチルスチレン単位の含有量が70モル%、アクリロニトリル単位の含有量が30モル%の共重合体を調製し、表1に記載の重量平均分子量15万の共重合体7を調製した。
共重合体1の調製において、スチレン単位の含有量が70モル%、アクリロニトリルの代わりにメタクリロニトリルを用いて、メタクリロニトリル単位の含有量が30モル%の共重合体を調製し表1に記載の、重量平均分子量20万の共重合体8を調製した。
〈共重合体(A)〉
共重合体1と同様にして、スチレン単位の含有量70モル%、アクリロニトリル単位の含有量30モル%であるスチレン-アクリロニトリル共重合体を調製した。以外は同様にして、表1に記載のように重量平均分子量20万の共重合体(A)を調製した。
撹拌装置、温度センサー、冷却管及び窒素導入管を備えた反応装置に、N-フェニルマレイミド52質量部と、スチレン73質量部と、重合連鎖移動剤としてn-ドデシルメルカプタン0.01質量部と、重合溶媒としてメチルイソブチルケトン100質量部とを仕込み、これに窒素を通じつつ、80℃まで昇温させた。昇温に伴う還流が始まったところで、重合開始剤として0.2質量部の2,2′-アゾビス(2-メチルイソブチロニトリル)を添加して、約80~85℃の環流下で7時間、溶液重合を進行させた。
上記調製した共重合体(A)及び共重合体(B)を表1に記載のように、質量比率70:30で混合して、表1に記載の共重合体9を調製した。
共重合体9の調製において、共重合体(A)及び共重合体(B)の混合比率を30:70とした以外は同様にして、表1に記載のように共重合体10を調製した。
共重合体9の調製において、共重合体(B)のみ使用(共重合体(A)及び共重合体(B)の混合比率を0:100)した以外は同様にして、表1に記載のように共重合体11を調製した。
〈共重合体(B)〉
共重合体9と同様にして、シクロヘキシルマレイミド単位の含有量が20モル%、メタクリル酸メチル単位の含有量が80モル%である、重量平均分子量15万の共重合体(B)を得た。
共重合体9の調製において、共重合体(B)のみ使用(共重合体(A)及び共重合体(B)の混合比率を0:100)した以外は同様にして、表1に記載のように共重合体12を調製した。
〈共重合体(A)〉
共重合体1と同様にして、スチレン単位の含有量70モル%、アクリロニトリル単位の含有量30モル%であるスチレン-アクリロニトリル共重合体を調製した。以外は同様にして、表1に記載のように重量平均分子量20万の共重合体(A)を調製した。
共重合体9と同様にして、シクロヘキシルマレイミド単位の含有量が30モル%、スチレン単位の含有量が70モル%である、重量平均分子量15万の共重合体(B)を得た。
上記調製した共重合体(A)及び共重合体(B)を表1に記載のように、質量比率70:30で混合して、表1に記載の共重合体13を調製した。
〈共重合体(A)〉
共重合体1と同様にして、スチレン単位の含有量55モル%、アクリロニトリル単位の含有量45モル%であるスチレン-アクリロニトリル共重合体を調製した。以外は同様にして、表1に記載のように重量平均分子量20万の共重合体(A)を調製した。
共重合体9と同様にして、N-フェニルマレイミド単位の含有量が25モル%、スチレン単位の含有量が55モル%、アクリロニトリル単位の含有量が20モル%である、重量平均分子量15万の共重合体(B)を得た。
上記調製した共重合体(A)及び共重合体(B)を表1に記載のように、質量比率70:30で混合して、表1に記載の共重合体14を調製した。
〈共重合体(A)〉
共重合体14と同様にして、スチレン単位の含有量55モル%、アクリロニトリル単位の含有量45モル%であるスチレン-アクリロニトリル共重合体を調製した。以外は同様にして、表1に記載のように重量平均分子量20万の共重合体(A)を調製した。
共重合体14と同様にして、N-フェニルマレイミド単位の含有量が25モル%、スチレン単位の含有量が55モル%、アクリロニトリル単位の含有量が20モル%である、重量平均分子量15万の共重合体(B)を得た。
上記調製した共重合体(A)及び共重合体(B)を表1に記載のように、質量比率90:10で混合して、表1に記載の共重合体15を調製した。
〈共重合体(A)〉
共重合体1と同様にして、スチレン単位の含有量70モル%、アクリロニトリル単位の含有量30モル%であるスチレン-アクリロニトリル共重合体を調製した。以外は同様にして、表1に記載のように重量平均分子量20万の共重合体(A)を調製した。
共重合体14と同様にして、N-フェニルマレイミド単位の含有量が20モル%、スチレン単位の含有量が20モル%、メタクリル酸メチル単位の含有量が60モル%である、重量平均分子量20万の共重合体(B)を得た。
上記調製した共重合体(A)及び共重合体(B)を表1に記載のように、質量比率70:30で混合して、表1に記載の共重合体16を調製した。
共重合体16の調製と同様にして、共重合体(A)、共重合体(B)を調製した。
上記調製した共重合体(A)及び共重合体(B)を表1に記載のように、質量比率50:50で混合して、表1に記載の共重合体17を調製した。
〈共重合体(A)〉
共重合体1と同様にして、スチレン単位の含有量70モル%、アクリロニトリル単位の含有量30モル%であるスチレン-アクリロニトリル共重合体を調製した。以外は同様にして、表1に記載のように重量平均分子量20万の共重合体(A)を調製した。
共重合体13と同様にして、シクロヘキシルマレイミド単位の含有量が20モル%、スチレン単位の含有量が20モル%、メタクリル酸メチル単位の含有量が60モル%である、重量平均分子量15万の共重合体(B)を得た。
上記調製した共重合体(A)及び共重合体(B)を表1に記載のように、質量比率70:30で混合して、表1に記載の共重合体18を調製した。
共重合体1の調製において、スチレン単位の含有量が90モル%、アクリロニトリル単位の含有量が10モル%のスチレン-アクリロニトリル共重合体を調製し、表1に記載の重量平均分子量25万の共重合体19を調製した。
<共重合体20の調製>
常法により、メタクリル酸メチル単位の含有量が95モル%、メタクリル酸単位の含有量が5モル%であるポリメチルメタクリレートである共重合体20を調製した。重量平均分子量は20万であり、表1に記載のように単独で使用した。
α-MSt:α-メチルスチレン
AN :アクリロニトリル
MN :メタクリロニトリル
PMI :N-フェニルマレイミド
CHMI :シクロヘキシルマレイミド
BzMI :ベンジルマレイミド
MMA :メタクリル酸メチル
MA :アクリル酸メチル
〈未反応モノマーの測定法〉
上記合成した共重合体1~10、13~19の共重合体(A)に含まれる未反応モノマーの含有量を、以下の方法で測定した。
カラム:J&W社製 DB-624(0.25mmi.d.×30ml)
オーブンプログラム:40℃(3min)-20℃/min-230℃(8min)
Inj:160℃
AUX:250℃
共重合体1~20の構成、及び共重合体1~10、13~19の上記未反応モノマーの測定結果を表1に示した。
1-1:エレカットS-412-2(竹本油脂(株)製):ドデシルベンゼンスルホン酸ナトリウム
1-2:エパン750(第一工業製薬(株)製):非イオン性界面活性剤
1-3:ステアリルアルコール
(3)ゴム粒子(化合物2)
2-1:タフプレン126S(旭化成ケミカルズ(株)製)スチレン-ブタジエン共重合体
2-2:TR2003(JSR(株)製)スチレン-ブタジエン共重合体
2-3:下記粒子1
2-4:下記粒子2
〈粒子1:下記方法で合成したアクリル粒子〉
(アクリル粒子C1)
内容積60リットルの還流冷却器付き反応器に、イオン交換水38.2リットル、ジオクチルスルホコハク酸ナトリウム111.6gを投入し、250rpmの回転数で撹拌しながら、窒素雰囲気下、75℃に昇温し、酸素の影響がない状態とした。過硫酸アンモニウム(APS)0.36gを投入し、5分間撹拌後にメチルメタクリレート(MMA)1657g、n-ブチルアクリレート(BA)21.6g、アリルメタクリレート(ALMA)1.68gからなる単量体の混合物を一括添加し、発熱ピークの検出後、さらに20分間保持して最内硬質層の重合を完結させた。
(弾性有機微粒子(B1))
撹拌機を備えた耐圧反応容器に、脱イオン水70部、ピロリン酸ナトリウム0.5部、オレイン酸カリウム0.2部、硫酸第一鉄0.005部、デキストロース0.2部、p-メンタンハイドロパーオキシド0.1部、1,3-ブタジエン28部からなる混合物を加え、65℃に昇温し、2時間重合反応を行った。次いで、得られた反応混合物に、p-メンタンハイドロパーオキシド0.2部を加えた後、1,3-ブタジエン72部、オレイン酸カリウム1.33部及び脱イオン水75部の混合物を2時間かけて連続滴下した。重合開始から21時間反応させて、体積平均粒子径0.240μmのブタジエン系ゴム重合体ラテックスを得た。
(偏光板保護フィルム101の作製)
下記成分を、撹拌及び加熱しながら十分に溶解させて、ドープ1を調製した。
共重合体1 100質量部
紫外線吸収剤 2-(2H-ベンゾトリアゾール-2-イル)-6-(1-メチル-1-フェニルエチル)-4-(1,1,3,3-テトラメチルブチル)フェノール](BASFジャパン社製のTi928) 3.0質量部
マット剤 R812(日本アエロジル社製、シリカ粒子、平均粒径8nm) 0.30質量部
剥離助剤 エレカットS-412-2(ドデシルベンゼンスルホン酸ナトリウム、竹本油脂社製) 0.20質量部
ゴム粒子 タフプレン126S(旭化成ケミカルズ(株)製)スチレン-ブタジエン共重合体 1質量部
ジクロロメタン 150質量部
エタノール 5質量部
調製したドープ1を、ベルト流延装置を用い、温度22℃、2m幅でステンレスバンド支持体に均一に流延した。ステンレスバンド支持体で、残留溶剤量が50%になるまで溶媒を蒸発させ、得られた膜状物を剥離張力162N/mでステンレスバンド支持体上から剥離した。
偏光板保護フィルム101の作製において、共重合体の種類(1~20)、化合物1及び化合物2の種類と量、及び膜厚をそれぞれ表3に記載のように変化させた以外は同様にして、偏光板保護フィルム102~125、129及び130を作製した。
(ペレットの作製)
共重合体1 100質量部
紫外線吸収剤 2,2′-メチレンビス[6-(2H-ベンゾトリアゾール-2-イル)-4-(1,1,3,3-テトラメチルブチル)フェノール](株式会社ADEKA製のLA31、分子量659) 3.0質量部
マット剤 R972V(日本アエロジル社製、シリカ粒子、平均粒径16nm) 0.30質量部
剥離助剤 エレカットS-412-2(ドデシルベンゼンスルホン酸ナトリウム、竹本油脂社製) 0.20質量部
ゴム粒子 タフプレン126S(旭化成ケミカルズ(株)製)スチレン-ブタジエン共重合体 1質量部
上記材料を、真空ナウターミキサーにて70℃、減圧下で3時間乾燥させた後、室温まで冷却した。得られた混合物を、二軸式押出機にて235℃で溶融混練して、ストランド状に押し出した。ストランド状に押し出された樹脂組成物を水冷した後、カッティングしてペレットを得た。
偏光板保護フィルム126の作製において、共重合体9を用いた以外は同様にして、膜厚40μmの偏光板保護フィルム127を得た。同様に共重合体20を用いて偏光板保護フィルム128を得た。
作製した偏光板保護フィルム101~130を用いて下記評価を実施し、結果を表2に示した。
耐熱性は、偏光板保護フィルムのガラス転移温度Tg(℃)によって評価し、Tg(℃)が高い程耐熱性に優れる。ガラス転移温度Tg(℃)は、JIS K-7121に従って、セイコーインスツル(株)製の示差走査熱量計DSC220を用いて測定する。
○:ガラス転移温度が、110℃以上、120℃未満の範囲内である
△:ガラス転移温度が、100℃以上、110℃未満の範囲内である
×:ガラス転移温度が、100℃未満である
(2)ヘイズ
ヘイズは、JIS K-7136に準拠して、ヘイズメーター(濁度計)(型式:NDH 2000、日本電色工業(株)製)にて測定する。
イエローインデックス(YI)は、JIS K-7105-6.3に記載の方法で求める。具体的なイエローインデックス値の測定方法としては、日立製作所製の分光光度計U-3200と附属の彩度計算プログラム等を用いて、色の三刺激値X、Y、Zを求め、下式に従ってイエローインデックス値を求める。
(4)折り曲げ耐性
〔折り曲げ強度の評価〕
偏光板保護フィルムを100mm(TD)×10mm(MD)で切り出し、23℃・55%RHの環境下で1時間放置後、縦方向の中央部で山折り、谷折りと二つにそれぞれ1回ずつ折りまげ、この評価を3回測定して、以下のように評価した。なお、ここでの評価の折れるとは、割れて二つ以上のピースに分離したことを表す。
○:3回とも、折れの発生が認められないが折った箇所の筋がやや強い
△:3回のうち少なくとも1回で、折れが発生している
×:3回とも折れが発生している
偏光板保護フィルム101~130の構成と上記評価結果を下記表2に示す。
(位相差フィルムAの作製)
下記成分を、ミキシングタンクに投入し、撹拌して各成分を溶解させた後、平均孔径34μmの濾紙及び平均孔径10μmの焼結金属フィルターで濾過して、下記組成のコア層用ドープ、スキンB層用ドープ及びスキンA層用ドープをそれぞれ調製した。
セルロースアセテート(総置換度2.45、アセチル基置換度2.45、重量平均分子量18万) 100質量部
化合物C(リターデーション上昇剤) 3質量部
化合物D(テレフタル酸/コハク酸/エタンジオール/プロパンジオール(80/20/50/50モル比)の縮合物の両末端をアセチルエステル基で封止したもの) 10質量部
ジクロロメタン 406質量部
メタノール 61質量部
セルロースアセテート(総置換度2.93、アセチル基置換度2.93、重量平均分子量28万) 100質量部
化合物E(テレフタル酸/コハク酸/エチレングリコール共重合体(50/50/100モル比)、分子量2000、リターデーション発現剤) 4質量部
アエロジルR972(日本エアロジル(株)製、二酸化ケイ素微粒子(平均粒径15nm、マット剤) 0.12質量部
クエン酸ハーフエチルエステル(扶桑化学工業(株)製、剥離促進剤) 2質量部
ジクロロメタン 406質量部
メタノール 61質量部
(スキンA層用ドープの組成)
クエン酸の部分エチルエステル(剥離促進剤)を含有させなかった以外は上記スキンB層用ドープの組成と同様とした。
下記成分を、ミキシングタンクに投入し、撹拌して各成分を溶解させた後、平均孔径34μmの濾紙及び平均孔径10μmの焼結金属フィルターで濾過して、下記組成のコア層用ドープ、スキンB層用ドープ及びスキンA層用ドープを、それぞれ調製した。
セルロースアセテート(総置換度2.45、アセチル基置換度2.45、重量平均分子量18万) 100質量部
化合物F(リターデーション上昇剤) 3質量部
化合物G(コハク酸/アジピン酸/エチレングリコール共重合体(共重合比=3:2:5、分子量2000)、リターデーション低減剤) 10質量部
ジクロロメタン 406質量部
メタノール 61質量部
セルロースアセテート(総置換度2.93、アセチル基置換度2.93、重量平均分子量28万) 100質量部
化合物E(テレフタル酸/コハク酸/エチレングリコール共重合体(50/50/100モル比)、分子量2000、リターデーション発現剤) 4質量部
アエロジルR972(日本エアロジル(株)製、二酸化ケイ素微粒子(平均粒径15nm、マット剤) 0.12質量部
N-(2,6-ジエチルフェニルカルバモイルメチル)イミノジ酢酸(剥離促進剤) 2質量部
ジクロロメタン 406質量部
メタノール 61質量部
(スキンA層用ドープ)
上記スキンB層用ドープの調製において、N-(2,6-ジエチルフェニルカルバモイルメチル)イミノジ酢酸(剥離促進剤)を含有させなかった以外は同様にして調製して、スキンA層用ドープを得た。
下記成分を、ディゾルバーで50分間撹拌混合した後、マントンゴーリンで分散して微粒子分散液1を得た。
微粒子(アエロジル R812 日本アエロジル(株)製)
11質量部
エタノール 89質量部
メチレンクロライドを入れた溶解タンクに、上記作製した微粒子分散液1をゆっくりと添加しながら、十分に撹拌した。得られた溶液を、二次粒子の粒径が所定の大きさとなるようにアトライターにて分散した後、日本精線(株)製のファインメットNFで濾過して、微粒子添加液1を調製した。
メチレンクロライド 99質量部
微粒子分散液1 5質量部
下記組成の主ドープを調製した。まず、加圧溶解タンクに、メチレンクロライドとエタノールを添加した後、アセチル基置換度2.40のセルロースアセテート、糖エステル化合物、重縮合エステル、リターデーション上昇剤及び微粒子添加液1を撹拌しながら投入した。これを加熱し、撹拌しながら、完全に溶解させた。得られた溶液を、安積濾紙(株)製の安積濾紙No.244を使用して濾過し、主ドープを調製した。
メチレンクロライド 365質量部
エタノール 50質量部
セルロースアセテート(アセチル置換度2.40、重量平均分子量28万) 84質量部
糖エステル1:平均置換度5.5のスクロースベンゾエート 10質量部
重縮合エステル:(フタル酸/アジピン酸/1,2-プロパンジオール=25/75/100モル比の縮合物の両末端を安息香酸エステル基で封止したもの、分子量440) 3質量部
リターデーション調整剤(化合物A) 3質量部
微粒子添加液1 1質量部
(偏光板101P及び偏光板101Uの作製)
1)偏光子の作製
厚さ30μmのポリビニルアルコールフィルムを、35℃の水で膨潤させた。得られたフィルムを、ヨウ素0.075g、ヨウ化カリウム5g及び水100gからなる水溶液に60秒間浸漬し、更にヨウ化カリウム3g、ホウ酸7.5g及び水100gからなる45℃の水溶液に浸漬した。得られたフィルムを、延伸温度55℃、延伸倍率2倍の条件で一軸延伸した。この一軸延伸フィルムを、水洗した後、乾燥させて、厚さ15μmの偏光子を得た。同様にして、延伸倍率を変更して厚さ10μmの偏光子を作製した。
完全ケン化型ポリビニルアルコール接着剤として、ポリビニルアルコール(クラレ製PVA-117H)3%水溶液を準備した。
下記の各成分を混合した後、脱泡して、活性エネルギー線硬化型接着剤液を調製した。なお、トリアリールスルホニウムヘキサフルオロホスフェートは、50%プロピレンカーボネート溶液として配合し、下記にはトリアリールスルホニウムヘキサフルオロホスフェートの固形分量を表示した。
エポリードGT-301(ダイセル化学社製の脂環式エポキシ樹脂) 40質量部
1,4-ブタンジオールジグリシジルエーテル 15質量部
トリアリールスルホニウムヘキサフルオロホスフェート
2.3質量部
9,10-ジブトキシアントラセン 0.1質量部
1,4-ジエトキシナフタレン 2.0質量部
4)偏光板の作製
まず、位相差フィルムとして、上記位相差フィルムCを準備し、その表面にコロナ放電処理を施した。なお、コロナ放電処理の条件は、コロナ出力強度2.0kW、ライン速度18m/分とした。次いで、位相差フィルムCのコロナ放電処理面に、上記作製した水糊又は活性エネルギー線硬化型接着剤液を、硬化後の膜厚が約3μmとなるようにバーコーターで塗工して、水糊層又は活性エネルギー線硬化型接着剤層を形成した。得られた水糊層又は活性エネルギー線硬化型接着剤層に、上記作製した厚さ15μmの偏光子を貼り合わせた。
偏光板101Uは、位相差フィルムC側から、ベルトコンベア付き紫外線照射装置(ランプは、フュージョンUVシステムズ社製のDバルブを使用)を用いて、積算光量が750mJ/cm2となるように紫外線を照射し、活性エネルギー線硬化型接着剤層を硬化させた。
偏光板101P及び偏光板101Uの作製において、偏光子(厚さ10μm及び15μm)、偏光板保護フィルム102~130、及び位相差フィルムA、B及びCを、表3記載のように組み合わせた以外は同様にして、偏光板102P~130P及び102U~130Uを作製した。
作製した各偏光板を50mm×50mmの大きさの正方形に断裁し、23℃、55%RHの雰囲気下に24時間放置した後、角の部分から偏光子と保護フィルムの界面で剥がした。この操作を各偏光板について評価を行い、偏光子と保護フィルムの間で剥がれがみられるか否かを目視観察し、下記の基準に従って接着性を評価した。
○:ほぼ全面にわたり、膜剥がれの発生が認められない
△:偏光板の4隅の一部で、ごく弱い剥離が認められるが、実用上許容される品質である
×:明らかな膜剥がれの発生が認められ、実用上問題となる品質である
5.液晶表示装置の作製
液晶セルとして、厚さが0.5mmの二枚のガラス基板と、それらの間に配置された液晶層とを有するVA方式の液晶セルを準備した。そして、上記準備した液晶セルの両面に、リンテック社製の厚さ25μmの両面テープ(基材レステープ MO-3005C)を介して上記作製した偏光板101Uをそれぞれ貼り合わせて、液晶表示パネルを得た。貼り合わせは、偏光板101Uの位相差フィルムCが液晶セルのガラス基板と接するように行った。
方式)から、液晶表示パネル(視認側偏光板/液晶セル/バックライト側偏光板の積層物)を取り外した後、上記作製した液晶表示パネルを配置して、液晶表示装置101を得た。取り付けた液晶表示パネルの偏光板の吸収軸が、あらかじめ貼られていた偏光板の吸収軸と同じ向きになるようにした。
上記作製した液晶表示装置を、40℃95%RHの環境下で24時間放置した。次いで、40℃ドライの環境下で液晶表示装置を黒表示させた状態で、表示画面の4頂点付近の輝度と表示画面中央部付近の輝度との差(中心部と周辺部との画像ムラ)を目視観察した。
△:ベンドムラが僅かに認められるが、実用上は許容される品質である
×:明らかなベンドムラが認められる
偏光板101P~128P、偏光板101U~128Uの構成及び上記の評価結果を、下記表3にまとめて示す。
3、6、12、15 濾過器
4、13 ストックタンク
5、14 送液ポンプ
8、16 導管
10 紫外線吸収剤仕込釜
20 合流管
21 混合機
30 ダイ
31 金属支持体
32 ウェブ
33 剥離位置
34 テンター装置
35 ローラー乾燥装置
41 仕込釜
42 ストック釜
43 ポンプ
44 濾過器
101 偏光板
102 偏光板保護フィルム
103A、103B 活性エネルギー線硬化型接着層
104 偏光子
105 位相差フィルム
106 液晶表示装置
107 液晶セル
Claims (15)
- 熱可塑性樹脂の主成分として、芳香族ビニルモノマーと不飽和ニトリルモノマーとを重合して得られる共重合体(A)と、イミド環構造を有する共重合体(B)とを、質量比率でA:B=100:0~50:50の範囲内で含有することを特徴とする偏光板保護フィルム。
- 前記芳香族ビニルモノマーと不飽和ニトリルモノマーとを重合して得られる共重合体(A)が、芳香族ビニルモノマー単位を50~75モル%の範囲内と不飽和ニトリルモノマー単位を25~50モル%の範囲内の比率で含有することを特徴とする請求項1に記載の偏光板保護フィルム。
- 前記芳香族ビニルモノマーがスチレンであり、また前記不飽和ニトリルモノマーがアクリロニトリルであることを特徴とする請求項1又は請求項2に記載の偏光板保護フィルム。
- 前記イミド環構造が、マレイミド構造又はグルタルイミド構造であることを特徴とする請求項1から請求項3のいずれか一項に記載の偏光板保護フィルム。
- さらに、炭素数8~22の直鎖状又は分岐状のアルキル基を有する酸、アルコール、金属塩、非イオン性界面活性剤又は非反応性4級アンモニウム塩型界面活性剤の少なくとも一種を、前記共重合体(A)及び(B)全体の質量に対して0.1~1.0質量%の範囲内で含有することを特徴とする請求項1から請求項4までのいずれか一項に記載の偏光板保護フィルム。
- さらに、コア・シェルタイプのアクリル微粒子、スチレン-共役ジエン系化合物又はブチルアクリレート系化合物の少なくとも一種を含有することを特徴とする請求項1から請求項5までのいずれか一項に記載の偏光板保護フィルム。
- 前記共重合体(A)が含有する芳香族ビニルモノマーと不飽和ニトリルモノマーの未反応モノマーが、それぞれ当該共重合体(A)の全質量に対して0.1質量%以下であることを特徴とする請求項1から請求項6までのいずれか一項に記載の偏光板保護フィルム。
- ヘイズが1.0%以下であり、かつイエローインデックス(YI)が1.0以下であることを特徴とする請求項1から請求項7までのいずれか一項に記載の偏光板保護フィルム。
- ポリビニルアルコール系偏光子に対して、ポリビニルアルコール系接着剤又は活性エネルギー線硬化型接着剤のいずれを用いても貼合できることを特徴とする請求項1から請求項8までのいずれか一項に記載の偏光板保護フィルム。
- 請求項1から請求項9までのいずれか一項に記載の偏光板保護フィルムを製造する偏光板保護フィルムの製造方法であって、前記偏光板保護フィルムを溶液流延法によって製造することを特徴とする偏光板保護フィルムの製造方法。
- 請求項1から請求項9までのいずれか一項に記載の偏光板保護フィルムと偏光子とを、ポリビニルアルコール系接着剤を用いて貼合したことを特徴とする偏光板。
- 請求項1から請求項9までのいずれか一項に記載の偏光板保護フィルムと偏光子とを、活性エネルギー線硬化型接着剤を用いて貼合したことを特徴とする偏光板。
- 請求項1から請求項9までのいずれか一項に記載の偏光板保護フィルムと偏光子を挟んで反対側の偏光板保護フィルムが、セルロースエステルフィルムであることを特徴とする請求項11又は請求項12に記載の偏光板。
- 前記偏光子の両面の接着剤が同一種類の接着剤であることを特徴とする請求項11から請求項13までのいずれか一項に記載の偏光板。
- 請求項1項から請求項9までのいずれか一項に記載の偏光板保護フィルムを、視認側偏光板の視認側及びバックライト側偏光板のバックライト側に配置することを特徴とする液晶表示装置。
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JPWO2020027078A1 (ja) * | 2018-07-31 | 2021-08-26 | コニカミノルタ株式会社 | (メタ)アクリル系樹脂フィルムおよび光学フィルム、(メタ)アクリル系樹脂フィルムの製造方法 |
WO2020027078A1 (ja) * | 2018-07-31 | 2020-02-06 | コニカミノルタ株式会社 | (メタ)アクリル系樹脂フィルムおよび光学フィルム、(メタ)アクリル系樹脂フィルムの製造方法 |
JP7298617B2 (ja) | 2018-07-31 | 2023-06-27 | コニカミノルタ株式会社 | (メタ)アクリル系樹脂フィルムおよび光学フィルム、(メタ)アクリル系樹脂フィルムの製造方法 |
JP7250040B2 (ja) | 2018-10-30 | 2023-03-31 | 富士フイルム株式会社 | フィルム、フィルムの製造方法、光学デバイス、及びフォルダブルデバイス |
JPWO2020090338A1 (ja) * | 2018-10-30 | 2021-09-30 | 富士フイルム株式会社 | フィルム、フィルムの製造方法、光学デバイス、及びフォルダブルデバイス |
WO2020090338A1 (ja) * | 2018-10-30 | 2020-05-07 | 富士フイルム株式会社 | フィルム、フィルムの製造方法、光学デバイス、及びフォルダブルデバイス |
WO2021084625A1 (ja) * | 2019-10-29 | 2021-05-06 | コニカミノルタ株式会社 | 偏光板、偏光板の製造方法および液晶表示装置 |
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JP2021089301A (ja) * | 2019-12-02 | 2021-06-10 | コニカミノルタ株式会社 | 光学フィルム及び光学フィルムの製造方法 |
JP7294094B2 (ja) | 2019-12-02 | 2023-06-20 | コニカミノルタ株式会社 | 光学フィルム及び光学フィルムの製造方法 |
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