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WO2015115359A1 - Master film for producing optical film - Google Patents

Master film for producing optical film Download PDF

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Publication number
WO2015115359A1
WO2015115359A1 PCT/JP2015/052002 JP2015052002W WO2015115359A1 WO 2015115359 A1 WO2015115359 A1 WO 2015115359A1 JP 2015052002 W JP2015052002 W JP 2015052002W WO 2015115359 A1 WO2015115359 A1 WO 2015115359A1
Authority
WO
WIPO (PCT)
Prior art keywords
film
producing
optical film
optical
raw
Prior art date
Application number
PCT/JP2015/052002
Other languages
French (fr)
Japanese (ja)
Inventor
勝啓 高藤
磯▲ざき▼ 孝徳
加藤 雅己
Original Assignee
株式会社クラレ
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社クラレ filed Critical 株式会社クラレ
Priority to KR1020167018581A priority Critical patent/KR102232980B1/en
Priority to CN201580006076.8A priority patent/CN105917256B/en
Priority to JP2015527725A priority patent/JP6408989B2/en
Publication of WO2015115359A1 publication Critical patent/WO2015115359A1/en

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Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/30Polarising elements
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B29C55/04Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08FMACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F216/00Copolymers 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
    • C08F216/02Copolymers 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 by an alcohol radical
    • C08F216/04Acyclic compounds
    • C08F216/06Polyvinyl alcohol ; Vinyl alcohol
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08FMACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F218/00Copolymers 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 acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid
    • C08F218/02Esters of monocarboxylic acids
    • C08F218/04Vinyl esters
    • C08F218/08Vinyl acetate
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08FMACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00Chemical modification by after-treatment
    • C08F8/12Hydrolysis
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18Manufacture of films or sheets
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/30Polarising elements
    • G02B5/3025Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033Polarisers, 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
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08FMACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2800/00Copolymer characterised by the proportions of the comonomers expressed
    • C08F2800/10Copolymer characterised by the proportions of the comonomers expressed as molar percentages
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2300/00Characterised by the use of unspecified polymers
    • C08J2300/10Polymers characterised by the presence of specified groups, e.g. terminal or pendant functional groups
    • C08J2300/104Polymers characterised by the presence of specified groups, e.g. terminal or pendant functional groups containing oxygen atoms
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2329/00Characterised 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
    • C08J2329/02Homopolymers or copolymers of unsaturated alcohols
    • C08J2329/04Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids

Definitions

  • the present invention relates to a raw film for producing an optical film such as a polarizing film containing a specific hydroxymethyl group-containing vinyl alcohol polymer and a method for producing an optical film using the same.
  • a polarizing plate having a light transmission and shielding function is a basic component of a liquid crystal display (LCD) together with a liquid crystal that changes a polarization state of light.
  • LCD liquid crystal display
  • Many polarizing plates have a structure in which a protective film such as a cellulose triacetate (TAC) film is bonded to the surface of a polarizing film.
  • TAC cellulose triacetate
  • a polarizing film a vinyl alcohol polymer film (hereinafter referred to as “vinyl alcohol-based heavy film”) is used.
  • iodine based dye coalescing the may be referred to as" PVA ) in a matrix formed by uniaxial stretching (I 3 - and I 5 -, etc.) or a dichroic dye such as dichroic organic dyes which are adsorbed Has become the mainstream.
  • LCDs have come to be used in a wide range of small devices such as calculators and watches, mobile phones, notebook computers, liquid crystal monitors, liquid crystal color projectors, liquid crystal televisions, in-vehicle navigation systems, and measurement devices used indoors and outdoors.
  • polarizing film there has been a demand for higher display quality.
  • high performance is also demanded for the polarizing film, and specifically, there is a demand for a polarizing film that has a high degree of polarization and transparency, excellent optical properties, and excellent hue.
  • high durability is also required for the polarizing film.
  • a polyvinyl alcohol film for a polarizing film made of a specific PVA containing 0.01 to 1 mol% of a hydrophilic functional group such as a carboxylic acid group or an ⁇ -hydroxy- ⁇ -olefin group is stretched and oriented. It is known that the processability and the adsorption processability of the dichroic substance are excellent (see Patent Document 1). In addition, it is known that a specific optical PVA film containing PVA containing a 1,2-glycol bond in the side chain is excellent in optical properties and stretchability (see Patent Document 2).
  • the present invention provides a raw film for producing an optical film that can easily produce an optical film with low shrinkage stress that is excellent in all of optical properties, hue, and durability, and a method for producing an optical film using the same.
  • the purpose is to provide.
  • a raw film for producing an optical film comprising a hydroxymethyl group-containing PVA having a structural unit content represented by the following formula (1) of 0.1 to 1.9 mol%;
  • R 1 represents an alkyl group having 1 to 3 carbon atoms.
  • [2] The raw film for producing an optical film according to [1], wherein the degree of polymerization of the hydroxymethyl group-containing PVA exceeds 2,000; [3] The raw film for producing an optical film according to [1] or [2], wherein the saponification degree of the hydroxymethyl group-containing PVA is 95 mol% or more; [4] The raw film for producing an optical film according to any one of [1] to [3], wherein the 1,2-glycol bond amount of the hydroxymethyl group-containing PVA is 1.5 mol% or less; [5] The raw film for producing an optical film according to any one of [1] to [4], wherein R 1 of the structural unit represented by the formula (1) is a methyl group; [6] The raw film for producing an optical film according to any one of [1] to [5], having a thickness of 60 ⁇ m or less; [7] The original film for producing an optical film according to any one of [1] to [1
  • the raw film for optical film manufacture which can manufacture easily the optical film with the low shrinkage stress which is excellent in all of an optical characteristic, a hue, and durability, and the manufacturing method of an optical film using the same Is provided.
  • the raw film for producing an optical film of the present invention contains a hydroxymethyl group-containing PVA in which the content of the structural unit represented by the following formula (1) is 0.1 to 1.9 mol%.
  • R 1 represents an alkyl group having 1 to 3 carbon atoms.
  • the raw film for producing an optical film of the present invention includes any one of optical properties, hues, and durability because the hydroxymethyl group-containing PVA contained therein contains the structural unit represented by the above formula (1) with a specific content. In addition, it is possible to easily produce an optical film having a low shrinkage stress.
  • the present invention is not limited in any way, the reason why the above-described advantages are obtained is that there is an influence of the crystallinity reduction based on the methylene group of the hydroxymethyl group in the structural unit represented by the formula (1), and the hydroxy group. This may be due to the high hydrogen bonding force based on the hydroxyl group of the methyl group.
  • R 1 represents an alkyl group having 1 to 3 carbon atoms.
  • the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.
  • R 1 is preferably a methyl group or an ethyl group, preferably a methyl group, since the hue of the optical film produced therefrom is improved as the crystallinity of the resulting optical film for producing an optical film decreases. Is particularly preferred.
  • the content of the structural unit represented by the formula (1) in the hydroxymethyl group-containing PVA is 0.1 to 1.9 mol%, where the number of moles of all the structural units constituting the hydroxymethyl group-containing PVA is 100 mol%. It is necessary to be within the range, and the content is preferably 0.2 mol% or more, more preferably 0.3 mol% or more, and further preferably 0.4 mol% or more. Preferably, it is preferably 1.8 mol% or less, more preferably 1.7 mol% or less, for example, 1.2 mol% or less, or 1.1 mol% or less.
  • the hue of the optical film manufactured from the raw film for optical film manufacture obtained by the said content rate being 0.1 mol% or more improves.
  • the structural unit refers to a repeating unit constituting a polymer.
  • the degree of polymerization degree of hydroxymethyl group containing PVA preferably exceeds 2,000, more preferably exceeds 2,100, and more preferably exceeds 2,200.
  • the upper limit of the degree of polymerization is not particularly limited, but the degree of polymerization is preferably 6,000 or less from the viewpoints of production cost and process passability during film formation.
  • the polymerization degree of the hydroxymethyl group-containing PVA in the present specification means an average polymerization degree measured according to the description of JIS K6726-1994.
  • the degree of saponification of the hydroxymethyl group-containing PVA is preferably 95 mol% or more, preferably 96 mol% or more, from the viewpoint of the water resistance of an optical film such as a polarizing film produced from the resulting optical film production raw film. More preferably, it is 98 mol% or more, for example, it may be 99 mol% or more, 99.7 mol% or more, or 99.8 mol% or more.
  • the degree of saponification of hydroxymethyl group-containing PVA is a structural unit (typical) of hydroxymethyl group-containing PVA that can be converted into vinyl alcohol units (—CH 2 —CH (OH) —) by saponification.
  • the degree of saponification can be measured according to the description of JIS K6726-1994, taking into consideration the amount of the structural unit represented by formula (1) and its derivatives.
  • the method for producing the hydroxymethyl group-containing PVA is not particularly limited.
  • a vinyl ester copolymer obtained by copolymerizing a vinyl ester monomer and an unsaturated monomer copolymerizable therewith and convertible to the structural unit represented by the formula (1) A method of converting a vinyl ester unit of the above into a vinyl alcohol unit, and further converting a structural unit derived from an unsaturated monomer that can be converted into a structural unit represented by the formula (1) into a structural unit represented by the formula (1) Is mentioned.
  • a specific example of the unsaturated monomer that can be converted into the structural unit represented by the formula (1) is shown in the following formula (2).
  • R 1 represents an alkyl group having 1 to 3 carbon atoms
  • R 2 represents an alkyl group having 1 to 10 carbon atoms.
  • R 2 is not particularly limited, and may be a linear alkyl group, or may partially have a branched or cyclic structure. Moreover, a part may be substituted with other functional groups.
  • R 2 is preferably an alkyl group having 1 to 5 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. And a linear or branched alkyl group such as a pentyl group.
  • Examples of the unsaturated monomer represented by the formula (2) include 2-methyl-2-propenyl acetate (methallyl acetate), 2-ethyl-2-propenyl acetate and the like. Of these, 2-methyl-2-propenyl acetate (methallyl acetate) is preferably used in terms of safety and ease of production.
  • the vinyl ester monomer used for the production of the hydroxymethyl group-containing PVA is not particularly limited.
  • vinyl acidate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl oleate, and vinyl benzoate from the economical viewpoint, vinyl acetate is preferred.
  • the polymerization method for copolymerizing the unsaturated monomer represented by formula (2) and the vinyl ester monomer may be any method such as batch polymerization, semi-batch polymerization, continuous polymerization, and semi-continuous polymerization.
  • the polymerization method known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method can be applied.
  • a bulk polymerization method or a solution polymerization method in which polymerization proceeds in a solvent-free or solvent such as alcohol is usually employed.
  • an emulsion polymerization method is also preferred.
  • the solvent of the solution polymerization method is not particularly limited, for example, alcohol.
  • the alcohol used as the solvent for the solution polymerization method is, for example, a lower alcohol such as methanol, ethanol, or propanol.
  • the amount of solvent used in the polymerization system may be selected in consideration of the chain transfer of the solvent in accordance with the degree of polymerization of the target hydroxymethyl group-containing PVA. For example, when the solvent is methanol, it is included in the solvent and the polymerization system.
  • the polymerization initiator used for copolymerization of the unsaturated monomer represented by the formula (2) and the vinyl ester monomer is a known polymerization initiator such as an azo initiator or a peroxide initiator.
  • the redox initiator may be selected according to the polymerization method.
  • Examples of the azo initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4- Dimethylvaleronitrile).
  • peroxide initiator examples include percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate; t-butyl peroxyneodecanate, ⁇ - Perester compounds such as cumylperoxyneodecanate; acetylcyclohexylsulfonyl peroxide; 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate; acetyl peroxide. Potassium persulfate, ammonium persulfate, hydrogen peroxide, or the like may be combined with the above initiator to form a polymerization initiator.
  • percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate
  • the redox initiator is, for example, a polymerization initiator in which the peroxide initiator is combined with a reducing agent such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, or longalite.
  • a reducing agent such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, or longalite.
  • the amount of the polymerization initiator used varies depending on the type of the polymerization initiator and cannot be determined unconditionally, but may be selected according to the polymerization rate. For example, when 2,2′-azobisisobutyronitrile or acetyl peroxide is used as the polymerization initiator, 0.01 to 0.2 mol% is preferable with respect to the vinyl ester monomer, and 0.02 to 0 More preferred is 15 mol%.
  • the copolymerization of the unsaturated monomer represented by the formula (2) and the vinyl ester monomer may be performed in the presence of a chain transfer agent.
  • the chain transfer agent include aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; mercaptans such as 2-hydroxyethanethiol; and phosphinic acid salts such as sodium phosphinate monohydrate. Of these, aldehydes and ketones are preferably used.
  • the amount of chain transfer agent used can be determined according to the chain transfer coefficient of the chain transfer agent to be used and the degree of polymerization of the target hydroxymethyl group-containing PVA. The amount is preferably 0.1 to 10 parts by mass.
  • the above hydroxymethyl group-containing PVA can be obtained by saponifying a vinyl ester copolymer obtained by copolymerization of an unsaturated monomer represented by formula (2) and a vinyl ester monomer. .
  • the vinyl ester unit in the vinyl ester copolymer is converted to a vinyl alcohol unit.
  • the ester bond of the structural unit derived from the unsaturated monomer represented by the formula (2) is also saponified and converted to the structural unit represented by the formula (1). Therefore, the hydroxymethyl group-containing PVA can be produced without further reaction such as hydrolysis after saponification.
  • the saponification of the vinyl ester copolymer can be performed in a state where the vinyl ester copolymer is dissolved in, for example, alcohol or hydrous alcohol.
  • the alcohol used for saponification include lower alcohols such as methanol and ethanol, preferably methanol.
  • the alcohol used for saponification may contain other solvents such as acetone, methyl acetate, ethyl acetate, and benzene at a ratio of 40% by mass or less of the mass, for example.
  • the catalyst used for saponification is, for example, an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide, an alkali catalyst such as sodium methylate, or an acid catalyst such as mineral acid.
  • the temperature at which saponification is performed is not limited, but is preferably within the range of 20 to 60 ° C.
  • the product is pulverized, washed and dried to obtain a hydroxymethyl group-containing PVA.
  • the saponification method is not limited to the method described above, and a known method can be applied.
  • the hydroxymethyl group-containing PVA can further include other structural units other than the structural unit represented by the formula (1), the vinyl alcohol unit, and the vinyl ester unit.
  • the other structural unit include a structural unit derived from an ethylenically unsaturated monomer copolymerizable with a vinyl ester monomer.
  • the proportion of the total of the structural unit represented by the formula (1), the vinyl alcohol unit and the vinyl ester unit is 100 mol% of the number of moles of all the structural units constituting the hydroxymethyl group-containing PVA. 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, particularly preferably 99 mol% or more, and 100 mol%. Also good.
  • ethylenically unsaturated monomer examples include ⁇ -olefins such as ethylene, propylene, n-butene, isobutylene and 1-hexene; acrylic acid and salts thereof; unsaturated monomer having an acrylate group.
  • Body methacrylic acid and salts thereof; unsaturated monomer having methacrylic ester group; acrylamide; N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and salts thereof Acrylamide derivatives such as acrylamidepropyldimethylamine and salts thereof (for example, quaternary salts); methacrylamide; N-methyl methacrylamide, N-ethyl methacrylamide, methacrylamide propane sulfonic acid and salts thereof, methacrylamide propylene Methacrylamide derivatives such as dimethylamine and its salts (eg quaternary salts); methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether , Vinyl
  • the arrangement order of the structural unit represented by the formula (1) in the hydroxymethyl group-containing PVA, the vinyl alcohol unit, and other arbitrary structural units is not particularly limited, and may be any of random, block, alternating, and the like.
  • the 1,2-glycol bond amount of the hydroxymethyl group-containing PVA is preferably 1.5 mol% or less, more preferably 1.4 mol% or less, and 1.2 mol% or less. Further preferred. When the 1,2-glycol bond amount of the hydroxymethyl group-containing PVA is within the above range, the durability of the optical film produced from the resulting optical film production raw film is improved.
  • a hydroxymethyl group-containing PVA having a 1,2-glycol bond content of 1.5 mol% or less is a raw material of a vinyl ester copolymer obtained by polymerizing a vinyl ester monomer at a temperature of 40 ° C. or less. Can be manufactured as.
  • the industrially possible lower limit of the polymerization temperature is about ⁇ 50 ° C.
  • the lower limit of the 1,2-glycol bond amount of the hydroxymethyl group-containing PVA is 0. Often about 5 mol% is the limit.
  • the 1,2-glycol bond amount is the number of moles of bonds between adjacent vinyl alcohol units bonded by 1,2-glycol bonds to the total number of moles of bonds between adjacent vinyl alcohol units.
  • the ratio (mol%) is referred to and can be determined by NMR measurement.
  • the raw film for producing an optical film of the present invention can contain a plasticizer in addition to the hydroxymethyl group-containing PVA.
  • Preferred plasticizers include polyhydric alcohols, and specific examples include ethylene glycol, glycerin, propylene glycol, diethylene glycol, diglycerin, triethylene glycol, tetraethylene glycol, trimethylolpropane, and the like.
  • the raw film for producing an optical film of the present invention can contain one or more of these plasticizers. Among these, glycerin is preferable in terms of the effect of improving stretchability.
  • the plasticizer content in the raw film for producing an optical film of the present invention is preferably in the range of 1 to 20 parts by mass with respect to 100 parts by mass of the hydroxymethyl group-containing PVA contained therein. More preferably, it is within the range of 5 parts by weight, and even more preferably within the range of 5 to 15 parts by weight.
  • the content is 1 part by mass or more, the stretchability of the film is further improved.
  • the content is 20 parts by mass or less, it is possible to prevent the film from becoming too flexible and handling properties from being lowered.
  • the raw film for producing an optical film of the present invention further includes a filler, a processing stabilizer such as a copper compound, a weather resistance stabilizer, a colorant, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, Flame retardants, other thermoplastic resins, lubricants, fragrances, defoamers, deodorants, extenders, release agents, mold release agents, reinforcing agents, cross-linking agents, fungicides, preservatives, crystallization rate retarders Additives such as can be blended as needed.
  • a processing stabilizer such as a copper compound, a weather resistance stabilizer, a colorant, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, Flame retardants, other thermoplastic resins, lubricants, fragrances, defoamers, deodorants, extenders, release agents, mold release agents, reinforcing agents, cross-linking agents, fungicides, preservatives, crystallization rate retarders
  • the proportion of the total of the hydroxymethyl group-containing PVA and the plasticizer in the raw film for producing an optical film of the present invention is preferably 80% by mass or more based on the mass of the original film for producing an optical film, 90 More preferably, it is more than 95 mass%, and it is still more preferable that it is 95 mass% or more.
  • the degree of swelling of the original film for producing an optical film of the present invention is preferably in the range of 160 to 240%, more preferably in the range of 170 to 230%, and in the range of 180 to 220%. It is particularly preferred.
  • the swelling degree is 160% or more, the film can be stably stretched to a higher magnification.
  • the degree of swelling is 240% or less, dissolution during stretching is suppressed, and stretching is possible even under higher temperature conditions.
  • the degree of swelling of the optical film-producing original film refers to the mass when the optical film-producing original film is immersed in distilled water at 30 ° C. for 30 minutes, and is dried at 105 ° C. for 16 hours after immersion.
  • the degree of swelling can be adjusted, for example, by changing the conditions for heat treatment, and the degree of swelling can usually be lowered by increasing the heat treatment temperature and lengthening the heat treatment time.
  • an optical film having excellent shrinkage stress and excellent optical characteristics, hue and durability can be easily produced. It can be used particularly effectively in a raw film for production.
  • the thickness of the raw film for producing an optical film is preferably 60 ⁇ m or less, more preferably 55 ⁇ m or less, further preferably 50 ⁇ m or less, particularly preferably 40 ⁇ m or less, and 35 ⁇ m or less. Is most preferable, and may be 25 ⁇ m or less, and further 20 ⁇ m or less. When the thickness is too thick, stretch spots tend to occur during uniaxial stretching for producing an optical film.
  • the thickness is preferably 1 ⁇ m or more because there is a tendency that stretching breakage is likely to occur during uniaxial stretching treatment for producing an optical film such as a polarizing film, More preferably, it is 5 ⁇ m or more, and further preferably 10 ⁇ m or more.
  • the width of the original film for producing an optical film of the present invention is not particularly limited, and can be determined according to the use of the produced optical film. In recent years, since the enlargement of screens of liquid crystal televisions and liquid crystal monitors has progressed, it is preferable for these applications to have a width of the original film for producing optical films of 3 m or more. On the other hand, if the width of the raw film for producing an optical film is too large, it is difficult to uniformly carry out uniaxial stretching itself when producing an optical film with an apparatus that has been put into practical use.
  • the width of the anti-film is preferably 7 m or less.
  • the production method of the raw film for producing an optical film of the present invention is not particularly limited, and a production method in which the thickness and width of the film after film formation are more uniform can be preferably employed.
  • Film formation in which one or two or more of the above-mentioned hydroxymethyl group-containing PVA constituting the anti-film and the above-described plasticizer, additive and surfactant described later are dissolved in a liquid medium as necessary.
  • the film-forming stock solution contains at least one of a plasticizer, an additive, and a surfactant, it is preferable that these components are uniformly mixed.
  • liquid medium used for the preparation of the membrane forming stock solution examples include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol. , Trimethylolpropane, ethylenediamine, diethylenetriamine and the like, and one or more of them can be used. Among these, water is preferable from the viewpoint of environmental load and recoverability.
  • the volatile fraction of the film-forming stock solution (content ratio in the film-forming stock solution of volatile components such as liquid media removed by volatilization or evaporation during film formation) varies depending on the film-forming method, film-forming conditions, etc. Specifically, it is preferably in the range of 50 to 95% by mass, more preferably in the range of 55 to 90% by mass, and still more preferably in the range of 60 to 85% by mass.
  • the film-forming stock solution has a volatile content of 50% by mass or more, so that the viscosity of the film-forming stock solution does not become too high, and filtration and defoaming are smoothly performed during the preparation of the film-forming stock solution, and there are few foreign substances and defects. Is easy to manufacture.
  • the volatile fraction of the film-forming stock solution is 95% by mass or less, the concentration of the film-forming stock solution does not become too low, and industrial film production is facilitated.
  • the film forming stock solution preferably contains a surfactant.
  • a surfactant By including the surfactant, the film-forming property is improved and the occurrence of uneven thickness of the film is suppressed, and the film is easily peeled off from the metal roll or belt used for film formation.
  • the film may contain a surfactant.
  • the kind of said surfactant is not specifically limited, From a viewpoint of the peelability from a metal roll or a belt, an anionic surfactant or a nonionic surfactant is preferable.
  • anionic surfactant for example, a carboxylic acid type such as potassium laurate; a sulfuric acid ester type such as polyoxyethylene lauryl ether sulfate and octyl sulfate; and a sulfonic acid type such as dodecylbenzene sulfonate are suitable.
  • a carboxylic acid type such as potassium laurate
  • a sulfuric acid ester type such as polyoxyethylene lauryl ether sulfate and octyl sulfate
  • a sulfonic acid type such as dodecylbenzene sulfonate
  • Nonionic surfactants include, for example, alkyl ether types such as polyoxyethylene oleyl ether; alkylphenyl ether types such as polyoxyethylene octylphenyl ether; alkyl ester types such as polyoxyethylene laurate; polyoxyethylene laurylamino Alkylamine type such as ether; alkylamide type such as polyoxyethylene lauric acid amide; polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether; alkanolamide type such as lauric acid diethanolamide and oleic acid diethanolamide; polyoxy An allyl phenyl ether type such as alkylene allyl phenyl ether is preferred.
  • surfactants can be used alone or in combination of two or more.
  • the content thereof is preferably in the range of 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the hydroxymethyl group-containing PVA contained in the film-forming stock solution.
  • the content is more preferably in the range of 0.02 to 0.3 parts by mass, and particularly preferably in the range of 0.05 to 0.1 parts by mass.
  • the content is 0.01 mass part or more, film forming property and peelability improve more.
  • the content is 0.5 parts by mass or less, it is possible to suppress that the surfactant bleeds out to the surface of the optical film-producing raw film, resulting in blocking and deterioration in handling properties. it can.
  • Examples of the film forming method for forming an optical film manufacturing raw film using the above film forming stock solution include a cast film forming method, an extrusion film forming method, a wet film forming method, and a gel film forming method. Can be mentioned. These film forming methods may be used alone or in combination of two or more. Among these film forming methods, the cast film forming method and the extrusion film forming method are preferable because a raw film for producing an optical film having a uniform thickness and width and good physical properties can be obtained. The formed film can be dried or heat-treated as necessary.
  • a method for producing a raw film for producing an optical film of the present invention for example, using the T-type slit die, hopper plate, I-die, lip coater die, etc.
  • the film discharged or cast uniformly on the peripheral surface of the rotating heated first roll (or belt) located on the upstream side and discharged or cast on the peripheral surface of the first roll (or belt) Volatile components are evaporated and dried from one side, and then further dried on the peripheral surface of one or more rotating heated rolls arranged downstream thereof, or in a hot air dryer
  • the method of winding with a winding device can be preferably employed industrially. Drying with a heated roll and drying with a hot air dryer may be performed in an appropriate combination.
  • the original film for producing an optical film of the present invention is used as an original film for producing an optical film.
  • Examples of such an optical film include a polarizing film and a retardation film, and a polarizing film is preferable.
  • Such an optical film can be produced, for example, by a method using the raw film for producing an optical film of the present invention, and a method having a uniaxial stretching process. Specifically, the optical film of the present invention is produced.
  • Film or the film derived from the original film for producing an optical film of the present invention hereinafter referred to as “the original film for producing an optical film of the present invention”).
  • the “films derived from the raw film for producing an optical film of the present invention” may be collectively referred to as “films according to the present invention”), and may be produced by a method having a step of uniaxially stretching.
  • the method for producing a polarizing film using the original film for producing an optical film of the present invention is not particularly limited, and any conventionally employed method may be adopted. Examples of such a method include a method in which a film based on the present invention is dyed and uniaxially stretched, or a film based on the present invention containing a dye is uniaxially stretched.
  • the film based on the present invention is subjected to swelling, dyeing, uniaxial stretching, and, if necessary, crosslinking treatment, fixing treatment, drying, heat treatment, etc.
  • a method is mentioned.
  • the order of each treatment such as swelling, dyeing, crosslinking treatment, uniaxial stretching, and fixing treatment is not particularly limited, and one or two or more treatments can be performed simultaneously. Also, one or more of each process can be performed twice or more.
  • Swelling can be performed by immersing the film according to the present invention in water.
  • the temperature of the water when immersed in water is preferably in the range of 20 to 40 ° C., more preferably in the range of 22 to 38 ° C., and preferably in the range of 25 to 35 ° C. Further preferred.
  • the time for immersion in water is preferably in the range of 0.1 to 5 minutes, for example, and more preferably in the range of 0.5 to 3 minutes.
  • the water at the time of immersing in water is not limited to pure water, The aqueous solution in which various components melt
  • Dyeing can be performed by bringing a dichroic dye into contact with the film according to the present invention.
  • the dichroic dye an iodine dye is generally used.
  • the dyeing time may be any stage before uniaxial stretching, during uniaxial stretching, or after uniaxial stretching.
  • Dyeing is generally performed by immersing the PVA film in a solution (particularly an aqueous solution) containing iodine-potassium iodide which is a dyeing bath, and such a dyeing method is also suitably employed in the present invention.
  • the iodine concentration in the dyeing bath is preferably in the range of 0.01 to 0.5% by mass, and the potassium iodide concentration is preferably in the range of 0.01 to 10% by mass.
  • the temperature of the dyeing bath is preferably 20 to 50 ° C., particularly 25 to 40 ° C.
  • the crosslinking treatment is preferably performed after the treatment for bringing the dichroic dye into contact and before the uniaxial stretching.
  • the crosslinking treatment can be performed by immersing the film according to the present invention in an aqueous solution containing a crosslinking agent.
  • a crosslinking agent one or more of boron compounds such as boric acid and borate such as borax can be used.
  • the concentration of the crosslinking agent in the aqueous solution containing the crosslinking agent is preferably in the range of 1 to 15% by mass, more preferably in the range of 2 to 7% by mass, and in the range of 3 to 6% by mass. More preferably. Sufficient stretchability can be maintained when the concentration of the crosslinking agent is in the range of 1 to 15% by mass.
  • the aqueous solution containing a crosslinking agent may contain potassium iodide and the like.
  • the temperature of the aqueous solution containing the crosslinking agent is preferably in the range of 20 to 50 ° C., particularly in the range of 25 to 40 ° C. By setting the temperature within the range of 20 to 50 ° C., crosslinking can be performed efficiently.
  • Uniaxial stretching of the film according to the present invention may be performed by either a wet stretching method or a dry stretching method.
  • the wet stretching method it can be carried out in an aqueous solution containing boric acid, or can be carried out in the dyeing bath described above or in a fixing treatment bath described later.
  • the stretching may be performed at room temperature, may be performed while heating, or may be performed in the air using the film based on the present invention after water absorption.
  • the wet stretching method is preferable because it can be uniformly stretched in the width direction, and uniaxial stretching is more preferable in an aqueous solution containing boric acid.
  • the concentration of boric acid in the boric acid aqueous solution is preferably within the range of 0.5 to 6.0% by mass, more preferably within the range of 1.0 to 5.0% by mass, It is particularly preferably within the range of ⁇ 4.0% by mass.
  • the aqueous boric acid solution may contain potassium iodide, and the concentration of potassium iodide is preferably in the range of 0.01 to 10% by mass.
  • the stretching temperature in the uniaxial stretching is preferably in the range of 30 to 90 ° C, more preferably in the range of 40 to 80 ° C, and particularly preferably in the range of 50 to 70 ° C.
  • the draw ratio in uniaxial stretching is preferably 6.6 times or more, more preferably 6.8 times or more, and 7.0 times or more from the viewpoint of the polarizing performance of the obtained polarizing film. Is particularly preferred.
  • the upper limit of the draw ratio is not particularly limited, but the draw ratio is preferably 8 times or less.
  • uniaxial stretching in the case of uniaxially stretching a long film according to the present invention there is no particular limitation on the direction of uniaxial stretching in the case of uniaxially stretching a long film according to the present invention, and uniaxial stretching or lateral uniaxial stretching in the long direction can be adopted. Since it is obtained, uniaxial stretching in the longitudinal direction is preferable. Uniaxial stretching in the longitudinal direction can be performed by changing the peripheral speed between the rolls using a stretching apparatus including a plurality of rolls parallel to each other. On the other hand, lateral uniaxial stretching can be performed using a tenter type stretching machine.
  • the fixing treatment bath used for the fixing treatment an aqueous solution containing one or more of boron compounds such as boric acid and borax can be used. Moreover, you may add an iodine compound and a metal compound in a fixed treatment bath as needed.
  • the concentration of the boron compound in the fixing treatment bath is generally about 2 to 15% by mass, particularly about 3 to 10% by mass. By setting the concentration within the range of 2 to 15% by mass, the adsorption of the dichroic dye can be further strengthened.
  • the temperature of the fixing treatment bath is preferably 15 to 60 ° C., particularly 25 to 40 ° C.
  • Drying conditions are not particularly limited, but it is preferable to perform the drying at a temperature within the range of 30 to 150 ° C, particularly within the range of 50 to 130 ° C.
  • a polarizing film excellent in dimensional stability can be easily obtained by drying at a temperature in the range of 30 to 150 ° C.
  • the contraction stress of the obtained polarizing film is 3 as the contraction stress in the length direction (stretching direction at the time of manufacturing the polarizing film) in the polarizing film after the humidity control is performed under the conditions of a temperature of 20 ° C. and a relative humidity of 20%. It is preferably 5 N / mm 2 or less. When the shrinkage stress is 3.5 N / mm 2 or less, the polarizing film is less likely to warp the LCD.
  • the shrinkage stress is more preferably 3.2 N / mm 2 or less, still more preferably 3N / mm 2 or less, particularly not less 2.7 N / mm 2 or less preferable.
  • the shrinkage stress for example 1N / mm 2 or more, or even at 2N / mm 2 or more.
  • the shrinkage stress can be measured as follows. That is, a humidity control process is first performed on a polarizing film sample (length 12 cm ⁇ width 1.5 cm) to be measured under conditions of a temperature of 20 ° C. and a relative humidity of 20%. Here, the humidity control process is performed to measure the shrinkage stress. When the humidity control process is not performed, the value of the contraction stress usually increases, but by performing this process, the value of the contraction stress can be decreased and a more accurate value can be obtained. . After performing the humidity control treatment, the length direction of this sample was fixed at 5 cm between chucks, and then stretched in the length direction under conditions of a temperature of 40 ° C. and a relative humidity of 5%, and the tension reached 2N.
  • the stretching is sometimes stopped and held, and in that state, the shrinkage stress (N / mm 2 ) in the length direction when the temperature is raised to 80 ° C. and 4 hours elapses is obtained. More specifically, the shrinkage stress can be measured by the method described later in the examples.
  • the polarizing film obtained as described above is usually used as a polarizing plate by attaching an optically transparent protective film having mechanical strength to both sides or one side.
  • an optically transparent protective film having mechanical strength to both sides or one side.
  • a cellulose triacetate (TAC) film, a cycloolefin polymer (COP) film, an acetic acid / cellulose butyrate (CAB) film, an acrylic film, a polyester film, or the like is used.
  • the adhesive for bonding include PVA adhesives, urethane adhesives, acrylate ultraviolet curable adhesives, and the like.
  • the polarizing plate obtained as described above can be used as an LCD component after being coated with an acrylic adhesive or the like and bonded to a glass substrate. At the same time, it may be bonded to a retardation film, a viewing angle improving film, a brightness improving film, or the like.
  • PVA Primary structure of PVA
  • the width of the width 5 cm ⁇ length 5 cm is uniaxially stretched.
  • a 5 cm ⁇ 8 cm long sample was cut. This sample was uniaxially stretched in the length direction by a factor of 1.5 while being immersed in pure water at 30 ° C. Subsequently, while being immersed in an aqueous solution (dyeing bath) (temperature 30 ° C.) containing 0.03% by mass of iodine and 3.0% by mass of potassium iodide for 60 seconds, the ratio is 1.6 times (2.4 in total). Uniaxially stretching in the length direction to adsorb iodine.
  • the length was 1.1 times (2.6 times in total) while being immersed in an aqueous solution (crosslinking bath) (temperature 30 ° C.) containing 3% by weight of boric acid and 3% by weight of potassium iodide. Uniaxially stretched in the direction. Further, while being immersed in an aqueous solution (stretching bath) containing 4% by mass of boric acid and 6% by mass of potassium iodide, the film is uniaxially stretched in the length direction until it is cut, and the raw film for producing an optical film before stretching.
  • the ratio of the length at the time of cutting with respect to the length of the film was defined as the limit stretch ratio.
  • the temperature of the stretching bath was changed by 1 ° C. from an appropriate temperature, the limiting stretching ratio was measured, and the temperature at which the limiting stretching ratio was the highest was selected.
  • Optical properties of polarizing film (dichroic ratio) (1) Measurement of transmittance Ts From the central part of the polarizing film obtained in the following examples or comparative examples, two 2 cm samples were taken in the length direction of the polarizing film, and a spectrophotometer with an integrating sphere (Japan) Using “V7100” manufactured by Spectroscopic Co., Ltd., in accordance with JIS Z 8722 (measuring method of object color), the visibility of the visible light region of the C light source and 2 ° field of view is corrected.
  • the transmittance Ts (%) and the degree of polarization V (%) were determined by the method described above, and the transmittance Ts (%) was plotted on the horizontal axis and the degree of polarization for each example and comparative example.
  • V (%) as the vertical axis, a total of 5 points including one point based on the transmittance Ts (%) and the degree of polarization V (%) of the polarizing film obtained in each example or comparative example are plotted on a graph.
  • V (%) as the vertical axis
  • a total of 5 points including one point based on the transmittance Ts (%) and the degree of polarization V (%) of the polarizing film obtained in each example or comparative example are plotted on a graph.
  • an approximate curve was obtained, and from the approximate curve, the degree of polarization V 44 (%) when the transmittance Ts (%) was 44% was obtained.
  • the dichroic ratio at a transmittance of 44% was determined by the following formula (6) and used as an index of polarization performance.
  • the higher the dichroic ratio the better the optical properties of the polarizing film.
  • Dichroic ratio when the transmittance 44% log (44 / 100-44 / 100 ⁇ V 44/100) / log (44/100 + 44/100 ⁇ V 44/100) (6)
  • the four polarizing films produced in the above-mentioned “Optical characteristics of the polarizing film (dichroic ratio)” with different amounts of adsorption of the dichroic dye, and each example or comparative example were obtained.
  • the absorbance (orthogonal absorbance) at a wavelength of 610 nm obtained when the transmittance was in the range of 44 to 45% and the transmittance T ⁇ (%) was measured out of the total of five polarizing films obtained.
  • One polarizing film of 2.95 to 3.05 was selected. The polarizing film was exposed for 4 hours in an environment of 60 ° C.
  • the residual rate of orthogonal absorbance (absorbance residual rate) D (%) determined by 7) was evaluated as the durability of the polarizing film. The higher the residual absorbance rate, the better the durability of the polarizing film. When the residual absorbance rate is 33% or more, it is judged as “ ⁇ ” (good), and when it is less than 33%, “x” (bad). It was determined. D (%) 100 ⁇ A 4h / A 0h (7)
  • the film was stretched in the length direction at a speed, and when the tension reached 2N, the stretching was stopped and held, and in that state, the temperature was raised to 80 ° C., and the tension after 4 hours was measured.
  • the contraction stress (contraction stress in the length direction) of the polarizing film was determined.
  • a case where the shrinkage stress was 3.5 N / mm 2 or less was determined as “ ⁇ ” (good), and a case where the shrinkage stress exceeded 3.5 N / mm 2 was determined as “x” (defective).
  • Example 1 100 parts by mass of a hydroxymethyl group-containing PVA shown in Table 1 obtained by saponifying a copolymer of vinyl acetate and 2-methyl-2-propenyl acetate as a modified PVA, 10 parts by mass of glycerin as a plasticizer, And an aqueous solution containing 0.1 part by mass of polyoxyethylene lauryl ether sodium sulfate as a surfactant and having a modified PVA content of 10% by mass as a film-forming stock solution, and drying it on a metal roll at 80 ° C.
  • the degree of swelling was adjusted to 200% by subjecting the obtained film to a heat treatment at a predetermined temperature for 1 minute in a hot air dryer to produce an original film for producing an optical film having a thickness of 30 ⁇ m.
  • the stretchability was evaluated by the above-described method using the obtained optical film for optical film production. The results are shown in Table 1.
  • the length was 1.1 times (2.6 times in total) while being immersed in an aqueous solution (crosslinking bath) (temperature 30 ° C.) containing 3% by weight of boric acid and 3% by weight of potassium iodide. Uniaxially stretched in the direction. Further, an aqueous solution (stretching bath) containing 4% by mass of boric acid and 6% by mass of potassium iodide (a temperature at which the limit stretching ratio determined in the above “stretchability of the raw film for producing optical film” becomes the highest) ) was uniaxially stretched in the length direction to a magnification 0.2 times lower than the limit draw ratio.
  • Example 2 In Example 1, hydroxymethyl group-containing PVA (Examples 2 to 5) shown in Table 1 obtained by saponifying a copolymer of vinyl acetate and 2-methyl-2-propenyl acetate as a modified PVA was used. Except for the above, a raw film for producing an optical film and a polarizing film were produced in the same manner as in Example 1, and each measurement or evaluation was performed. The results are shown in Table 1.
  • Example 1 unmodified PVA shown in Table 1 obtained by saponifying a homopolymer of vinyl acetate instead of modified PVA (Comparative Example 1); vinyl acetate and 2-methyl-2-acetate as modified PVA Hydroxymethyl group-containing PVA shown in Table 1 obtained by saponifying a copolymer with propenyl (Comparative Example 2); As a modified PVA, a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene was used.
  • Modified PVA shown in Table 1 obtained by saponification (Comparative Example 3); Modified PVA shown in Table 1 obtained by saponifying a copolymer of vinyl acetate and itaconic acid as modified PVA (Comparative Example 4) Or modified PVA shown in Table 1 obtained by saponifying a copolymer of vinyl acetate and 7-acetoxy-1-heptene as modified PVA (Reference Example 1) Except for the use respectively, to produce a raw film and polarizing film for an optical film prepared in the same manner as in Example 1 were each measured or evaluated. The results are shown in Table 1.
  • the optical film having a low shrinkage stress which is excellent in all of optical characteristics, hue and durability. It can be seen that can be easily manufactured.

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Abstract

[Problem] To provide: a master film for producing an optical film, which enables easy production of an optical film that has excellent optical characteristics, hue and durability, while having low contraction stress; and a method for producing an optical film, which uses this master film. [Solution] A master film for producing an optical film, which contains a hydroxymethyl group-containing vinyl alcohol polymer that contains 0.1-1.9% by mole of a structural unit represented by formula (1); and a method for producing an optical film using this master film for producing an optical film, which comprises a step for uniaxial stretching. (In the formula, R1 represents an alkyl group having 1-3 carbon atoms.)

Description

光学フィルム製造用原反フィルムRaw film for optical film production
 本発明は、特定のヒドロキシメチル基含有ビニルアルコール系重合体を含む、偏光フィルム等の光学フィルムを製造するための原反フィルムと、それを用いた光学フィルムの製造方法に関する。 The present invention relates to a raw film for producing an optical film such as a polarizing film containing a specific hydroxymethyl group-containing vinyl alcohol polymer and a method for producing an optical film using the same.
 光の透過及び遮蔽機能を有する偏光板は、光の偏光状態を変化させる液晶と共に液晶ディスプレイ(LCD)の基本的な構成要素である。多くの偏光板は偏光フィルムの表面に三酢酸セルロース(TAC)フィルムなどの保護膜が貼り合わされた構造を有しており、偏光フィルムとしてはビニルアルコール系重合体フィルム(以下、「ビニルアルコール系重合体」を「PVA」と称することがある)を一軸延伸してなるマトリックスにヨウ素系色素(I やI 等)や二色性有機染料といった二色性色素が吸着しているものが主流となっている。 A polarizing plate having a light transmission and shielding function is a basic component of a liquid crystal display (LCD) together with a liquid crystal that changes a polarization state of light. Many polarizing plates have a structure in which a protective film such as a cellulose triacetate (TAC) film is bonded to the surface of a polarizing film. As a polarizing film, a vinyl alcohol polymer film (hereinafter referred to as “vinyl alcohol-based heavy film”) is used. iodine based dye coalescing "the may be referred to as" PVA ") in a matrix formed by uniaxial stretching (I 3 - and I 5 -, etc.) or a dichroic dye such as dichroic organic dyes which are adsorbed Has become the mainstream.
 LCDは、電卓及び腕時計などの小型機器、携帯電話、ノートパソコン、液晶モニター、液晶カラープロジェクター、液晶テレビ、車載用ナビゲーションシステム、屋内外で用いられる計測機器などの広範囲において用いられるようになってきており、近年、特に表示品質の高級化が要求されている。これに伴い、偏光フィルムに対しても高性能化が求められており、具体的には、偏光度や透過度が高くて光学特性に優れると共に、色相にも優れる偏光フィルムが求められている。一方で、偏光フィルムには高い耐久性も求められている。 LCDs have come to be used in a wide range of small devices such as calculators and watches, mobile phones, notebook computers, liquid crystal monitors, liquid crystal color projectors, liquid crystal televisions, in-vehicle navigation systems, and measurement devices used indoors and outdoors. In recent years, there has been a demand for higher display quality. Along with this, high performance is also demanded for the polarizing film, and specifically, there is a demand for a polarizing film that has a high degree of polarization and transparency, excellent optical properties, and excellent hue. On the other hand, high durability is also required for the polarizing film.
 ところで、変性PVAを含む光学フィルム製造用原反フィルムがいくつか知られている。例えば、カルボン酸基やω-ヒドロキシ-α-オレフィン基などの親水性の官能基を0.01~1モル%含有する特定のPVAからなる偏光膜の原反用ポリビニルアルコールフィルムが、延伸・配向処理性及び二色性物質の吸着処理性に優れることが知られている(特許文献1を参照)。また、側鎖に1,2-グリコール結合を含有するPVAを含む特定の光学用PVAフィルムが、光学特性及び延伸性に優れることが知られている(特許文献2を参照)。 By the way, several raw film films for producing optical films containing modified PVA are known. For example, a polyvinyl alcohol film for a polarizing film made of a specific PVA containing 0.01 to 1 mol% of a hydrophilic functional group such as a carboxylic acid group or an ω-hydroxy-α-olefin group is stretched and oriented. It is known that the processability and the adsorption processability of the dichroic substance are excellent (see Patent Document 1). In addition, it is known that a specific optical PVA film containing PVA containing a 1,2-glycol bond in the side chain is excellent in optical properties and stretchability (see Patent Document 2).
特開平8-201626号公報JP-A-8-201626 特開2009-24076号公報JP 2009-24076 A
 しかしながら、従来公知の変性PVAを含む光学フィルム製造用原反フィルムを用いた場合には、光学特性、色相及び耐久性のいずれにも優れる光学フィルムを得るという点で、さらなる改良の余地があった。また最近ではLCDの薄型化が進行しており、これを達成するための手段としてLCDに用いられるガラスを薄型化することが挙げられるが、これに伴う偏光フィルム等の光学フィルムの収縮応力によるガラスの反りの問題を解消するなどの観点から、収縮応力の低い光学フィルムが望まれる。 However, in the case of using a conventionally known raw film for producing an optical film containing modified PVA, there is room for further improvement in that an optical film having excellent optical properties, hue, and durability is obtained. . In recent years, LCDs have been made thinner, and as a means for achieving this, it is possible to reduce the thickness of glass used in LCDs. From the standpoint of solving the problem of warping, an optical film having a low shrinkage stress is desired.
 そこで本発明は、光学特性、色相及び耐久性のいずれにも優れる収縮応力の低い光学フィルムを容易に製造することのできる光学フィルム製造用原反フィルムと、それを用いた光学フィルムの製造方法を提供することを目的とする。 Therefore, the present invention provides a raw film for producing an optical film that can easily produce an optical film with low shrinkage stress that is excellent in all of optical properties, hue, and durability, and a method for producing an optical film using the same. The purpose is to provide.
 本発明者らが上記の目的を達成すべく鋭意検討を重ねた結果、特定の構造単位を主鎖に含む特定のヒドロキシメチル基含有PVAを含むフィルムによれば上記課題が解決されることを見出し、当該知見に基づいてさらに検討を重ねて本発明を完成させた。 As a result of intensive studies by the present inventors to achieve the above object, it has been found that the above problems can be solved by a film containing a specific hydroxymethyl group-containing PVA containing a specific structural unit in the main chain. The present invention was completed through further studies based on the findings.
 すなわち、本発明は、
[1]下記式(1)で示される構造単位の含有率が0.1~1.9モル%であるヒドロキシメチル基含有PVAを含む、光学フィルム製造用原反フィルム;
That is, the present invention
[1] A raw film for producing an optical film, comprising a hydroxymethyl group-containing PVA having a structural unit content represented by the following formula (1) of 0.1 to 1.9 mol%;
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
[式中、Rは炭素数1~3のアルキル基を示す。]
[2]前記ヒドロキシメチル基含有PVAの重合度が2,000を超える、[1]に記載の光学フィルム製造用原反フィルム;
[3]前記ヒドロキシメチル基含有PVAのけん化度が95モル%以上である、[1]または[2]に記載の光学フィルム製造用原反フィルム;
[4]前記ヒドロキシメチル基含有PVAの1,2-グリコール結合量が1.5モル%以下である、[1]~[3]のいずれか1つに記載の光学フィルム製造用原反フィルム;
[5]前記式(1)で示される構造単位のRがメチル基である、[1]~[4]のいずれか1つに記載の光学フィルム製造用原反フィルム;
[6]厚みが60μm以下である、[1]~[5]のいずれか1つに記載の光学フィルム製造用原反フィルム;
[7]偏光フィルム製造用原反フィルムである、[1]~[6]のいずれか1つに記載の光学フィルム製造用原反フィルム;
[8][1]~[7]のいずれか1つに記載の光学フィルム製造用原反フィルムを用いる光学フィルムの製造方法であって一軸延伸する工程を有する製造方法;
に関する。
[Wherein R 1 represents an alkyl group having 1 to 3 carbon atoms. ]
[2] The raw film for producing an optical film according to [1], wherein the degree of polymerization of the hydroxymethyl group-containing PVA exceeds 2,000;
[3] The raw film for producing an optical film according to [1] or [2], wherein the saponification degree of the hydroxymethyl group-containing PVA is 95 mol% or more;
[4] The raw film for producing an optical film according to any one of [1] to [3], wherein the 1,2-glycol bond amount of the hydroxymethyl group-containing PVA is 1.5 mol% or less;
[5] The raw film for producing an optical film according to any one of [1] to [4], wherein R 1 of the structural unit represented by the formula (1) is a methyl group;
[6] The raw film for producing an optical film according to any one of [1] to [5], having a thickness of 60 μm or less;
[7] The original film for producing an optical film according to any one of [1] to [6], which is an original film for producing a polarizing film;
[8] A method for producing an optical film using the raw film for producing an optical film according to any one of [1] to [7], comprising a step of uniaxial stretching;
About.
 本発明によれば、光学特性、色相及び耐久性のいずれにも優れる収縮応力の低い光学フィルムを容易に製造することのできる光学フィルム製造用原反フィルムと、それを用いた光学フィルムの製造方法が提供される。 ADVANTAGE OF THE INVENTION According to this invention, the raw film for optical film manufacture which can manufacture easily the optical film with the low shrinkage stress which is excellent in all of an optical characteristic, a hue, and durability, and the manufacturing method of an optical film using the same Is provided.
 本発明の光学フィルム製造用原反フィルムは、下記式(1)で示される構造単位の含有率が0.1~1.9モル%であるヒドロキシメチル基含有PVAを含む。 The raw film for producing an optical film of the present invention contains a hydroxymethyl group-containing PVA in which the content of the structural unit represented by the following formula (1) is 0.1 to 1.9 mol%.
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
[式中、Rは炭素数1~3のアルキル基を示す。] [Wherein R 1 represents an alkyl group having 1 to 3 carbon atoms. ]
 本発明の光学フィルム製造用原反フィルムは、それに含まれるヒドロキシメチル基含有PVAが上記式(1)で示される構造単位を特定の含有量で含むことにより、光学特性、色相及び耐久性のいずれにも優れる収縮応力の低い光学フィルムを容易に製造することができる。本発明を何ら限定するものではないが、上記のような利点が得られる理由としては、式(1)で示される構造単位におけるヒドロキシメチル基のメチレン基に基づく結晶性低下の影響と、当該ヒドロキシメチル基のヒドロキシル基に基づく高い水素結合力による影響とが考えられる。 The raw film for producing an optical film of the present invention includes any one of optical properties, hues, and durability because the hydroxymethyl group-containing PVA contained therein contains the structural unit represented by the above formula (1) with a specific content. In addition, it is possible to easily produce an optical film having a low shrinkage stress. Although the present invention is not limited in any way, the reason why the above-described advantages are obtained is that there is an influence of the crystallinity reduction based on the methylene group of the hydroxymethyl group in the structural unit represented by the formula (1), and the hydroxy group. This may be due to the high hydrogen bonding force based on the hydroxyl group of the methyl group.
 上記式(1)で示される構造単位において、Rは炭素数1~3のアルキル基を示す。当該炭素数1~3のアルキル基としては、例えば、メチル基、エチル基、n-プロピル基、イソプロピル基が挙げられる。得られる光学フィルム製造用原反フィルムの結晶性が低下するほど、それから製造される光学フィルムの色相が向上することから、Rはメチル基またはエチル基であることが好ましく、メチル基であることが特に好ましい。 In the structural unit represented by the above formula (1), R 1 represents an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. R 1 is preferably a methyl group or an ethyl group, preferably a methyl group, since the hue of the optical film produced therefrom is improved as the crystallinity of the resulting optical film for producing an optical film decreases. Is particularly preferred.
 ヒドロキシメチル基含有PVAにおける式(1)で示される構造単位の含有率は、ヒドロキシメチル基含有PVAを構成する全構造単位のモル数を100モル%として、0.1~1.9モル%の範囲内であることが必要であり、当該含有率は0.2モル%以上であることが好ましく、0.3モル%以上であることがより好ましく、0.4モル%以上であることがさらに好ましく、また、1.8モル%以下であることが好ましく、1.7モル%以下であることがより好ましく、例えば、1.2モル%以下、あるいは1.1モル%以下としてもよい。当該含有率が0.1モル%以上であることにより、得られる光学フィルム製造用原反フィルムから製造される光学フィルムの色相が向上する。一方、当該含有率が1.9モル%以下であることにより、得られる光学フィルム製造用原反フィルムを用いて光学フィルムを製造する際におけるフィルムの溶解が効果的に防止され、また当該光学フィルム製造用原反フィルムから製造される光学フィルムの光学特性が向上する。なお本明細書において、構造単位とは重合体を構成する繰り返し単位のことをいう。 The content of the structural unit represented by the formula (1) in the hydroxymethyl group-containing PVA is 0.1 to 1.9 mol%, where the number of moles of all the structural units constituting the hydroxymethyl group-containing PVA is 100 mol%. It is necessary to be within the range, and the content is preferably 0.2 mol% or more, more preferably 0.3 mol% or more, and further preferably 0.4 mol% or more. Preferably, it is preferably 1.8 mol% or less, more preferably 1.7 mol% or less, for example, 1.2 mol% or less, or 1.1 mol% or less. The hue of the optical film manufactured from the raw film for optical film manufacture obtained by the said content rate being 0.1 mol% or more improves. On the other hand, when the content is 1.9 mol% or less, dissolution of the film when the optical film is produced using the obtained optical film production raw film is effectively prevented, and the optical film is produced. The optical properties of the optical film produced from the production raw film are improved. In the present specification, the structural unit refers to a repeating unit constituting a polymer.
 ヒドロキシメチル基含有PVAの重合度に特に制限はなく、例えば、1,500以上とすることができるが、得られる光学フィルム製造用原反フィルムから製造される光学フィルムの光学特性及び耐久性が向上することから、当該重合度は、2,000を超えることが好ましく、2,100を超えることがより好ましく、2,200を超えることがさらに好ましい。一方、当該重合度の上限にも特に制限はないが、製造コストや、製膜時における工程通過性などの観点から、当該重合度は6,000以下であることが好ましい。なお、本明細書におけるヒドロキシメチル基含有PVAの重合度は、JIS K6726-1994の記載に準じて測定した平均重合度を意味する。 There is no restriction | limiting in particular in the polymerization degree of hydroxymethyl group containing PVA, For example, although it can be set to 1,500 or more, the optical characteristic and durability of the optical film manufactured from the raw film for optical film manufacture obtained improve Therefore, the degree of polymerization preferably exceeds 2,000, more preferably exceeds 2,100, and more preferably exceeds 2,200. On the other hand, the upper limit of the degree of polymerization is not particularly limited, but the degree of polymerization is preferably 6,000 or less from the viewpoints of production cost and process passability during film formation. In addition, the polymerization degree of the hydroxymethyl group-containing PVA in the present specification means an average polymerization degree measured according to the description of JIS K6726-1994.
 ヒドロキシメチル基含有PVAのけん化度は、得られる光学フィルム製造用原反フィルムから製造される偏光フィルム等の光学フィルムの耐水性の点から、95モル%以上であることが好ましく、96モル%以上であることがより好ましく、98モル%以上であることがさらに好ましく、例えば、99モル%以上、99.7モル%以上、あるいは99.8モル%以上としてもよい。なお、本明細書におけるヒドロキシメチル基含有PVAのけん化度とは、ヒドロキシメチル基含有PVAが有する、けん化によってビニルアルコール単位(-CH-CH(OH)-)に変換され得る構造単位(典型的にはビニルエステル単位)とビニルアルコール単位との合計モル数に対して、当該ビニルアルコール単位のモル数が占める割合(モル%)をいう。当該けん化度は、式(1)で示される構造単位やその誘導体の量も勘案した上でJIS K6726-1994の記載に準じて測定することができる。 The degree of saponification of the hydroxymethyl group-containing PVA is preferably 95 mol% or more, preferably 96 mol% or more, from the viewpoint of the water resistance of an optical film such as a polarizing film produced from the resulting optical film production raw film. More preferably, it is 98 mol% or more, for example, it may be 99 mol% or more, 99.7 mol% or more, or 99.8 mol% or more. In this specification, the degree of saponification of hydroxymethyl group-containing PVA is a structural unit (typical) of hydroxymethyl group-containing PVA that can be converted into vinyl alcohol units (—CH 2 —CH (OH) —) by saponification. Is the ratio (mol%) of the number of moles of the vinyl alcohol unit to the total number of moles of the vinyl ester unit) and the vinyl alcohol unit. The degree of saponification can be measured according to the description of JIS K6726-1994, taking into consideration the amount of the structural unit represented by formula (1) and its derivatives.
 ヒドロキシメチル基含有PVAの製造方法は特に限定されない。例えば、ビニルエステル系単量体と、それと共重合可能でありかつ式(1)で示される構造単位に変換可能な不飽和単量体とを共重合し、得られたビニルエステル系共重合体のビニルエステル単位をビニルアルコール単位に変換し、さらに式(1)で示される構造単位に変換可能な不飽和単量体に由来する構造単位を式(1)で示される構造単位に変換する方法が挙げられる。式(1)で示される構造単位に変換可能な不飽和単量体の具体例を以下の式(2)に示す。 The method for producing the hydroxymethyl group-containing PVA is not particularly limited. For example, a vinyl ester copolymer obtained by copolymerizing a vinyl ester monomer and an unsaturated monomer copolymerizable therewith and convertible to the structural unit represented by the formula (1) A method of converting a vinyl ester unit of the above into a vinyl alcohol unit, and further converting a structural unit derived from an unsaturated monomer that can be converted into a structural unit represented by the formula (1) into a structural unit represented by the formula (1) Is mentioned. A specific example of the unsaturated monomer that can be converted into the structural unit represented by the formula (1) is shown in the following formula (2).
Figure JPOXMLDOC01-appb-C000004
Figure JPOXMLDOC01-appb-C000004
[式中、Rは炭素数1~3のアルキル基を示し、Rは炭素数1~10のアルキル基を示す。] [Wherein R 1 represents an alkyl group having 1 to 3 carbon atoms, and R 2 represents an alkyl group having 1 to 10 carbon atoms. ]
 式(2)において、Rに関する説明は、式(1)におけるRのものと同様であり、ここでは重複する記載を省略する。 In the formula (2), description of R 1 are the same as those of R 1 in the formula (1) are omitted, wherein the overlapping here.
 式(2)において、Rの構造としては特に限定されず、直鎖アルキル基であってもよいし、一部に分岐、環状構造を有していてもよい。また、一部が他の官能基で置換されていてもよい。Rは好ましくは炭素数1~5のアルキル基であり、該アルキル基の例としては、メチル基、エチル基、n-プロピル基、イソプロピル基、n-ブチル基、イソブチル基、tert-ブチル基、ペンチル基などの直鎖または分岐を有するアルキル基が挙げられる。 In the formula (2), the structure of R 2 is not particularly limited, and may be a linear alkyl group, or may partially have a branched or cyclic structure. Moreover, a part may be substituted with other functional groups. R 2 is preferably an alkyl group having 1 to 5 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. And a linear or branched alkyl group such as a pentyl group.
 式(2)で示される不飽和単量体としては、例えば、酢酸2-メチル-2-プロペニル(酢酸メタリル)、酢酸2-エチル-2-プロペニルなどが挙げられる。中でも、酢酸2-メチル-2-プロペニル(酢酸メタリル)が安全性及び製造容易性の点で好ましく用いられる。 Examples of the unsaturated monomer represented by the formula (2) include 2-methyl-2-propenyl acetate (methallyl acetate), 2-ethyl-2-propenyl acetate and the like. Of these, 2-methyl-2-propenyl acetate (methallyl acetate) is preferably used in terms of safety and ease of production.
 ヒドロキシメチル基含有PVAの製造に用いられるビニルエステル系単量体は特に限定されないが、例えば、蟻酸ビニル、酢酸ビニル、プロピオン酸ビニル、酪酸ビニル、イソ酪酸ビニル、ピバリン酸ビニル、バーサチック酸ビニル、カプロン酸ビニル、カプリル酸ビニル、カプリン酸ビニル、ラウリン酸ビニル、パルミチン酸ビニル、ステアリン酸ビニル、オレイン酸ビニル、安息香酸ビニルなどが挙げられる。経済的観点からは酢酸ビニルが好ましい。 The vinyl ester monomer used for the production of the hydroxymethyl group-containing PVA is not particularly limited. For example, vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, capron Examples thereof include vinyl acidate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl oleate, and vinyl benzoate. From the economical viewpoint, vinyl acetate is preferred.
 式(2)で示される不飽和単量体とビニルエステル系単量体とを共重合する際の重合方式は、回分重合、半回分重合、連続重合、半連続重合などのいずれの方式でもよく、重合方法としては、塊状重合法、溶液重合法、懸濁重合法、乳化重合法などの公知の方法を適用することができる。無溶媒またはアルコールなどの溶媒中で重合を進行させる塊状重合法または溶液重合法が通常採用される。高重合度のビニルエステル系共重合体を得る場合には乳化重合法も好ましい。溶液重合法の溶媒は特に限定されないが、例えばアルコールである。溶液重合法の溶媒に使用されるアルコールは、例えばメタノール、エタノール、プロパノールなどの低級アルコールである。重合系における溶媒の使用量は、目的とするヒドロキシメチル基含有PVAの重合度に応じて溶媒の連鎖移動を考慮して選択すればよく、例えば溶媒がメタノールの場合、溶媒と重合系に含まれる全単量体との質量比{=(溶媒)/(全単量体)}として、好ましくは0.01~10の範囲内、より好ましくは0.05~3の範囲内から選択される。 The polymerization method for copolymerizing the unsaturated monomer represented by formula (2) and the vinyl ester monomer may be any method such as batch polymerization, semi-batch polymerization, continuous polymerization, and semi-continuous polymerization. As the polymerization method, known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method can be applied. A bulk polymerization method or a solution polymerization method in which polymerization proceeds in a solvent-free or solvent such as alcohol is usually employed. In order to obtain a vinyl ester copolymer having a high degree of polymerization, an emulsion polymerization method is also preferred. Although the solvent of the solution polymerization method is not particularly limited, for example, alcohol. The alcohol used as the solvent for the solution polymerization method is, for example, a lower alcohol such as methanol, ethanol, or propanol. The amount of solvent used in the polymerization system may be selected in consideration of the chain transfer of the solvent in accordance with the degree of polymerization of the target hydroxymethyl group-containing PVA. For example, when the solvent is methanol, it is included in the solvent and the polymerization system. The mass ratio with respect to all monomers {= (solvent) / (total monomers)} is preferably selected within the range of 0.01 to 10, more preferably within the range of 0.05 to 3.
 式(2)で示される不飽和単量体とビニルエステル系単量体との共重合に使用される重合開始剤は、公知の重合開始剤、例えばアゾ系開始剤、過酸化物系開始剤、レドックス系開始剤から重合方法に応じて選択すればよい。アゾ系開始剤は、例えば2,2’-アゾビスイソブチロニトリル、2,2’-アゾビス(2,4-ジメチルバレロニトリル)、2,2’-アゾビス(4-メトキシ-2,4-ジメチルバレロニトリル)である。過酸化物系開始剤は、例えばジイソプロピルパーオキシジカーボネート、ジ-2-エチルヘキシルパーオキシジカーボネート、ジエトキシエチルパーオキシジカーボネートなどのパーカーボネート系化合物;t-ブチルパーオキシネオデカネート、α-クミルパーオキシネオデカネートなどのパーエステル系化合物;アセチルシクロヘキシルスルホニルパーオキシド;2,4,4-トリメチルペンチル-2-パーオキシフェノキシアセテート;過酸化アセチルである。過硫酸カリウム、過硫酸アンモニウム、過酸化水素などを上記開始剤に組み合わせて重合開始剤としてもよい。レドックス系開始剤は、例えば上記の過酸化物系開始剤と亜硫酸水素ナトリウム、炭酸水素ナトリウム、酒石酸、L-アスコルビン酸、ロンガリットなどの還元剤とを組み合わせた重合開始剤である。重合開始剤の使用量は、重合開始剤の種類により異なるために一概には決められないが、重合速度に応じて選択すればよい。例えば重合開始剤に2,2’-アゾビスイソブチロニトリルあるいは過酸化アセチルを用いる場合、ビニルエステル系単量体に対して0.01~0.2モル%が好ましく、0.02~0.15モル%がより好ましい。 The polymerization initiator used for copolymerization of the unsaturated monomer represented by the formula (2) and the vinyl ester monomer is a known polymerization initiator such as an azo initiator or a peroxide initiator. The redox initiator may be selected according to the polymerization method. Examples of the azo initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4- Dimethylvaleronitrile). Examples of the peroxide initiator include percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate; t-butyl peroxyneodecanate, α- Perester compounds such as cumylperoxyneodecanate; acetylcyclohexylsulfonyl peroxide; 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate; acetyl peroxide. Potassium persulfate, ammonium persulfate, hydrogen peroxide, or the like may be combined with the above initiator to form a polymerization initiator. The redox initiator is, for example, a polymerization initiator in which the peroxide initiator is combined with a reducing agent such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, or longalite. The amount of the polymerization initiator used varies depending on the type of the polymerization initiator and cannot be determined unconditionally, but may be selected according to the polymerization rate. For example, when 2,2′-azobisisobutyronitrile or acetyl peroxide is used as the polymerization initiator, 0.01 to 0.2 mol% is preferable with respect to the vinyl ester monomer, and 0.02 to 0 More preferred is 15 mol%.
 式(2)で示される不飽和単量体とビニルエステル系単量体との共重合は、連鎖移動剤の存在下で行ってもよい。連鎖移動剤は、例えばアセトアルデヒド、プロピオンアルデヒドなどのアルデヒド類;アセトン、メチルエチルケトンなどのケトン類;2-ヒドロキシエタンチオールなどのメルカプタン類;ホスフィン酸ナトリウム一水和物などのホスフィン酸塩類などである。中でもアルデヒド類及びケトン類が好適に用いられる。連鎖移動剤の使用量は、使用する連鎖移動剤の連鎖移動係数及び目的とするヒドロキシメチル基含有PVAの重合度に応じて決定することができるが、一般にビニルエステル系単量体100質量部に対して0.1~10質量部が好ましい。 The copolymerization of the unsaturated monomer represented by the formula (2) and the vinyl ester monomer may be performed in the presence of a chain transfer agent. Examples of the chain transfer agent include aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; mercaptans such as 2-hydroxyethanethiol; and phosphinic acid salts such as sodium phosphinate monohydrate. Of these, aldehydes and ketones are preferably used. The amount of chain transfer agent used can be determined according to the chain transfer coefficient of the chain transfer agent to be used and the degree of polymerization of the target hydroxymethyl group-containing PVA. The amount is preferably 0.1 to 10 parts by mass.
 式(2)で示される不飽和単量体とビニルエステル系単量体との共重合により得られるビニルエステル系共重合体をけん化することにより、上記のヒドロキシメチル基含有PVAを得ることができる。当該ビニルエステル系共重合体をけん化することによって、ビニルエステル系共重合体中のビニルエステル単位はビニルアルコール単位に変換される。また、式(2)で示される不飽和単量体に由来する構造単位のエステル結合もけん化され、式(1)で示される構造単位に変換される。したがって、当該ヒドロキシメチル基含有PVAは、けん化後にさらに加水分解等の反応を行わなくても製造することができる。 The above hydroxymethyl group-containing PVA can be obtained by saponifying a vinyl ester copolymer obtained by copolymerization of an unsaturated monomer represented by formula (2) and a vinyl ester monomer. . By saponifying the vinyl ester copolymer, the vinyl ester unit in the vinyl ester copolymer is converted to a vinyl alcohol unit. In addition, the ester bond of the structural unit derived from the unsaturated monomer represented by the formula (2) is also saponified and converted to the structural unit represented by the formula (1). Therefore, the hydroxymethyl group-containing PVA can be produced without further reaction such as hydrolysis after saponification.
 ビニルエステル系共重合体のけん化は、例えばアルコールまたは含水アルコールに当該ビニルエステル系共重合体が溶解した状態で行うことができる。けん化に使用するアルコールは、例えばメタノール、エタノールなどの低級アルコールが挙げられ、好ましくはメタノールである。けん化に使用するアルコールは、例えばその質量の40質量%以下の割合で、アセトン、酢酸メチル、酢酸エチル、ベンゼンなどの他の溶媒を含んでもよい。けん化に使用する触媒は、例えば水酸化カリウム、水酸化ナトリウムなどのアルカリ金属の水酸化物、ナトリウムメチラートなどのアルカリ触媒、鉱酸などの酸触媒である。けん化を行う温度は限定されないが、20~60℃の範囲内が好適である。けん化の進行にしたがってゲル状の生成物が析出してくる場合には、生成物を粉砕した後、洗浄、乾燥して、ヒドロキシメチル基含有PVAを得ることができる。けん化方法は、前述した方法に限らず公知の方法を適用できる。 The saponification of the vinyl ester copolymer can be performed in a state where the vinyl ester copolymer is dissolved in, for example, alcohol or hydrous alcohol. Examples of the alcohol used for saponification include lower alcohols such as methanol and ethanol, preferably methanol. The alcohol used for saponification may contain other solvents such as acetone, methyl acetate, ethyl acetate, and benzene at a ratio of 40% by mass or less of the mass, for example. The catalyst used for saponification is, for example, an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide, an alkali catalyst such as sodium methylate, or an acid catalyst such as mineral acid. The temperature at which saponification is performed is not limited, but is preferably within the range of 20 to 60 ° C. When a gel-like product precipitates as saponification proceeds, the product is pulverized, washed and dried to obtain a hydroxymethyl group-containing PVA. The saponification method is not limited to the method described above, and a known method can be applied.
 ヒドロキシメチル基含有PVAは、式(1)で示される構造単位、ビニルアルコール単位及びビニルエステル単位以外の他の構造単位をさらに含むことができる。当該他の構造単位としては、例えばビニルエステル系単量体と共重合可能なエチレン性不飽和単量体に由来する構造単位が挙げられる。また、上記したビニルエステル系単量体と共重合可能でありかつ式(1)で示される構造単位に変換可能な不飽和単量体に由来する構造単位(けん化により式(1)で示される構造単位に変換されなかった構造単位)を含むこともできる。 The hydroxymethyl group-containing PVA can further include other structural units other than the structural unit represented by the formula (1), the vinyl alcohol unit, and the vinyl ester unit. Examples of the other structural unit include a structural unit derived from an ethylenically unsaturated monomer copolymerizable with a vinyl ester monomer. Further, a structural unit derived from an unsaturated monomer that can be copolymerized with the above-described vinyl ester monomer and can be converted to a structural unit represented by the formula (1) (shown by the formula (1) by saponification). A structural unit that has not been converted to a structural unit).
 ヒドロキシメチル基含有PVAにおける、式(1)で示される構造単位、ビニルアルコール単位及びビニルエステル単位の合計の占める割合は、ヒドロキシメチル基含有PVAを構成する全構造単位のモル数を100モル%として、80モル%以上であることが好ましく、90モル%以上であることがより好ましく、95モル%以上であることがさらに好ましく、99モル%以上であることが特に好ましく、100モル%であってもよい。 In the hydroxymethyl group-containing PVA, the proportion of the total of the structural unit represented by the formula (1), the vinyl alcohol unit and the vinyl ester unit is 100 mol% of the number of moles of all the structural units constituting the hydroxymethyl group-containing PVA. 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, particularly preferably 99 mol% or more, and 100 mol%. Also good.
 上記のエチレン性不飽和単量体としては、例えば、エチレン、プロピレン、n-ブテン、イソブチレン、1-ヘキセンなどのα-オレフィン類;アクリル酸及びその塩;アクリル酸エステル基を有する不飽和単量体;メタクリル酸及びその塩;メタクリル酸エステル基を有する不飽和単量体;アクリルアミド;N-メチルアクリルアミド、N-エチルアクリルアミド、N,N-ジメチルアクリルアミド、ジアセトンアクリルアミド、アクリルアミドプロパンスルホン酸及びその塩、アクリルアミドプロピルジメチルアミン及びその塩(例えば4級塩)などのアクリルアミド誘導体;メタクリルアミド;N-メチルメタクリルアミド、N-エチルメタクリルアミド、メタクリルアミドプロパンスルホン酸及びその塩、メタクリルアミドプロピルジメチルアミン及びその塩(例えば4級塩)などのメタクリルアミド誘導体;メチルビニルエーテル、エチルビニルエーテル、n-プロピルビニルエーテル、i-プロピルビニルエーテル、n-ブチルビニルエーテル、i-ブチルビニルエーテル、t-ブチルビニルエーテル、ドデシルビニルエーテル、ステアリルビニルエーテル、2,3-ジアセトキシ-1-ビニルオキシプロパンなどのビニルエーテル類;アクリロニトリル、メタクリロニトリルなどのシアン化ビニル類;塩化ビニル、フッ化ビニルなどのハロゲン化ビニル類;塩化ビニリデン、フッ化ビニリデンなどのハロゲン化ビニリデン類;酢酸アリル、2,3-ジアセトキシ-1-アリルオキシプロパン、塩化アリルなどのアリル化合物;マレイン酸、イタコン酸、フマル酸などの不飽和ジカルボン酸及びその塩またはエステル;ビニルトリメトキシシランなどのビニルシリル化合物;酢酸イソプロペニルである。 Examples of the ethylenically unsaturated monomer include α-olefins such as ethylene, propylene, n-butene, isobutylene and 1-hexene; acrylic acid and salts thereof; unsaturated monomer having an acrylate group. Body; methacrylic acid and salts thereof; unsaturated monomer having methacrylic ester group; acrylamide; N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and salts thereof Acrylamide derivatives such as acrylamidepropyldimethylamine and salts thereof (for example, quaternary salts); methacrylamide; N-methyl methacrylamide, N-ethyl methacrylamide, methacrylamide propane sulfonic acid and salts thereof, methacrylamide propylene Methacrylamide derivatives such as dimethylamine and its salts (eg quaternary salts); methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether , Vinyl ethers such as stearyl vinyl ether and 2,3-diacetoxy-1-vinyloxypropane; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene chloride and fluoride Vinylidene halides such as vinylidene; allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, allyl chloride; maleic acid, itaconic acid, fumaric acid, etc. Unsaturated dicarboxylic acids and salts or esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate.
 ヒドロキシメチル基含有PVAにおける式(1)で示される構造単位、ビニルアルコール単位及びその他任意の構成単位の配列順序には特に制限はなく、ランダム、ブロック、交互などのいずれであってもよい。 The arrangement order of the structural unit represented by the formula (1) in the hydroxymethyl group-containing PVA, the vinyl alcohol unit, and other arbitrary structural units is not particularly limited, and may be any of random, block, alternating, and the like.
 ヒドロキシメチル基含有PVAの1,2-グリコール結合量は、1.5モル%以下であることが好ましく、1.4モル%以下であることがより好ましく、1.2モル%以下であることがさらに好ましい。ヒドロキシメチル基含有PVAの1,2-グリコール結合量が上記範囲にあることにより、得られる光学フィルム製造用原反フィルムから製造される光学フィルムの耐久性が向上する。1,2-グリコール結合量が1.5モル%以下のヒドロキシメチル基含有PVAは、ビニルエステル系単量体を40℃以下の温度で重合することにより得られたビニルエステル系共重合体を原料として製造することができる。ビニルエステル系単量体の重合速度の点から工業的に可能な重合温度の下限は-50℃程度であり、この観点から、ヒドロキシメチル基含有PVAの1,2-グリコール結合量の下限は0.5モル%程度が限度であることが多い。なお、1,2-グリコール結合量とは隣接するビニルアルコール単位間の結合の全モル数に対して1,2-グリコール結合で結合している隣接するビニルアルコール単位間の結合のモル数が占める割合(モル%)をいい、NMR測定法により求めることができる。 The 1,2-glycol bond amount of the hydroxymethyl group-containing PVA is preferably 1.5 mol% or less, more preferably 1.4 mol% or less, and 1.2 mol% or less. Further preferred. When the 1,2-glycol bond amount of the hydroxymethyl group-containing PVA is within the above range, the durability of the optical film produced from the resulting optical film production raw film is improved. A hydroxymethyl group-containing PVA having a 1,2-glycol bond content of 1.5 mol% or less is a raw material of a vinyl ester copolymer obtained by polymerizing a vinyl ester monomer at a temperature of 40 ° C. or less. Can be manufactured as. From the viewpoint of the polymerization rate of the vinyl ester monomer, the industrially possible lower limit of the polymerization temperature is about −50 ° C. From this viewpoint, the lower limit of the 1,2-glycol bond amount of the hydroxymethyl group-containing PVA is 0. Often about 5 mol% is the limit. The 1,2-glycol bond amount is the number of moles of bonds between adjacent vinyl alcohol units bonded by 1,2-glycol bonds to the total number of moles of bonds between adjacent vinyl alcohol units. The ratio (mol%) is referred to and can be determined by NMR measurement.
 本発明の光学フィルム製造用原反フィルムは、上記のヒドロキシメチル基含有PVAの他に可塑剤を含むことができる。好ましい可塑剤としては多価アルコールが挙げられ、具体例としては、エチレングリコール、グリセリン、プロピレングリコール、ジエチレングリコール、ジグリセリン、トリエチレングリコール、テトラエチレングリコール、トリメチロールプロパンなどが挙げられる。本発明の光学フィルム製造用原反フィルムはこれらの可塑剤の1種または2種以上を含むことができる。これらの中でも、延伸性の向上効果の点からグリセリンが好ましい。 The raw film for producing an optical film of the present invention can contain a plasticizer in addition to the hydroxymethyl group-containing PVA. Preferred plasticizers include polyhydric alcohols, and specific examples include ethylene glycol, glycerin, propylene glycol, diethylene glycol, diglycerin, triethylene glycol, tetraethylene glycol, trimethylolpropane, and the like. The raw film for producing an optical film of the present invention can contain one or more of these plasticizers. Among these, glycerin is preferable in terms of the effect of improving stretchability.
 本発明の光学フィルム製造用原反フィルムにおける可塑剤の含有量は、それに含まれるヒドロキシメチル基含有PVA100質量部に対して、1~20質量部の範囲内であることが好ましく、3~17質量部の範囲内であることがより好ましく、5~15質量部の範囲内であることがさらに好ましい。当該含有量が1質量部以上であることによりフィルムの延伸性がより向上する。一方、当該含有量が20質量部以下であることにより、フィルムが柔軟になり過ぎて取り扱い性が低下するのを抑制することができる。 The plasticizer content in the raw film for producing an optical film of the present invention is preferably in the range of 1 to 20 parts by mass with respect to 100 parts by mass of the hydroxymethyl group-containing PVA contained therein. More preferably, it is within the range of 5 parts by weight, and even more preferably within the range of 5 to 15 parts by weight. When the content is 1 part by mass or more, the stretchability of the film is further improved. On the other hand, when the content is 20 parts by mass or less, it is possible to prevent the film from becoming too flexible and handling properties from being lowered.
 本発明の光学フィルム製造用原反フィルムには、さらに、充填剤、銅化合物などの加工安定剤、耐候性安定剤、着色剤、紫外線吸収剤、光安定剤、酸化防止剤、帯電防止剤、難燃剤、他の熱可塑性樹脂、潤滑剤、香料、消泡剤、消臭剤、増量剤、剥離剤、離型剤、補強剤、架橋剤、防かび剤、防腐剤、結晶化速度遅延剤などの添加剤を、必要に応じて適宜配合できる。 The raw film for producing an optical film of the present invention further includes a filler, a processing stabilizer such as a copper compound, a weather resistance stabilizer, a colorant, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, Flame retardants, other thermoplastic resins, lubricants, fragrances, defoamers, deodorants, extenders, release agents, mold release agents, reinforcing agents, cross-linking agents, fungicides, preservatives, crystallization rate retarders Additives such as can be blended as needed.
 本発明の光学フィルム製造用原反フィルムにおけるヒドロキシメチル基含有PVA及び可塑剤の合計の占める割合は、光学フィルム製造用原反フィルムの質量に基づいて、80質量%以上であることが好ましく、90質量%以上であることがより好ましく、95質量%以上であることがさらに好ましい。 The proportion of the total of the hydroxymethyl group-containing PVA and the plasticizer in the raw film for producing an optical film of the present invention is preferably 80% by mass or more based on the mass of the original film for producing an optical film, 90 More preferably, it is more than 95 mass%, and it is still more preferable that it is 95 mass% or more.
 本発明の光学フィルム製造用原反フィルムの膨潤度は、160~240%の範囲内であることが好ましく、170~230%の範囲内であることがより好ましく、180~220%の範囲内であることが特に好ましい。膨潤度が160%以上であることにより、安定してより高倍率まで延伸することができる。一方、膨潤度が240%以下であることにより、延伸時の溶解が抑制され、より高温の条件下でも延伸することが可能となる。なお本明細書において、光学フィルム製造用原反フィルムの膨潤度とは、光学フィルム製造用原反フィルムを30℃の蒸留水中に30分間浸漬した際の質量を、浸漬後105℃で16時間乾燥した後の質量で除して得られる値の百分率を意味し、具体的には実施例において後述する方法により測定することができる。膨潤度は例えば熱処理の条件を変更することによって調整することができ、通常、熱処理温度を高くして熱処理時間を長くすることによって膨潤度を低下させることができる。 The degree of swelling of the original film for producing an optical film of the present invention is preferably in the range of 160 to 240%, more preferably in the range of 170 to 230%, and in the range of 180 to 220%. It is particularly preferred. When the swelling degree is 160% or more, the film can be stably stretched to a higher magnification. On the other hand, when the degree of swelling is 240% or less, dissolution during stretching is suppressed, and stretching is possible even under higher temperature conditions. In this specification, the degree of swelling of the optical film-producing original film refers to the mass when the optical film-producing original film is immersed in distilled water at 30 ° C. for 30 minutes, and is dried at 105 ° C. for 16 hours after immersion. It means the percentage of the value obtained by dividing by the mass after the measurement, and can be specifically measured by the method described later in the examples. The degree of swelling can be adjusted, for example, by changing the conditions for heat treatment, and the degree of swelling can usually be lowered by increasing the heat treatment temperature and lengthening the heat treatment time.
 本発明の光学フィルム製造用原反フィルムによれば、光学特性、色相及び耐久性のいずれにも優れる収縮応力の低い光学フィルムを容易に製造することができることから、従来よりも厚みの薄い光学フィルム製造用原反フィルムにおいて特に有効に用いることができる。光学フィルム製造用原反フィルムの厚みは60μm以下であることが好ましく、55μm以下であることがより好ましく、50μm以下であることがさらに好ましく、40μm以下であることが特に好ましく、35μm以下であることが最も好ましく、25μm以下、さらには20μm以下であってもよい。当該厚みが厚すぎると、光学フィルムを製造するための一軸延伸処理時に延伸斑が発生しやすくなる傾向がある。なお、当該厚みが薄すぎると、偏光フィルム等の光学フィルムを製造するための一軸延伸処理時に、延伸切れが発生しやすくなる傾向があることから、当該厚みは、1μm以上であることが好ましく、5μm以上であることがより好ましく、10μm以上であることがさらに好ましい。 According to the raw film for producing an optical film of the present invention, an optical film having excellent shrinkage stress and excellent optical characteristics, hue and durability can be easily produced. It can be used particularly effectively in a raw film for production. The thickness of the raw film for producing an optical film is preferably 60 μm or less, more preferably 55 μm or less, further preferably 50 μm or less, particularly preferably 40 μm or less, and 35 μm or less. Is most preferable, and may be 25 μm or less, and further 20 μm or less. When the thickness is too thick, stretch spots tend to occur during uniaxial stretching for producing an optical film. In addition, when the thickness is too thin, the thickness is preferably 1 μm or more because there is a tendency that stretching breakage is likely to occur during uniaxial stretching treatment for producing an optical film such as a polarizing film, More preferably, it is 5 μm or more, and further preferably 10 μm or more.
 本発明の光学フィルム製造用原反フィルムの幅は特に制限されず、製造される光学フィルムの用途などに応じて決めることができる。近年、液晶テレビや液晶モニターの大画面化が進行している点から光学フィルム製造用原反フィルムの幅を3m以上にしておくと、これらの用途に好適である。一方、光学フィルム製造用原反フィルムの幅があまりに大きすぎると実用化されている装置で光学フィルムを製造する場合に一軸延伸自体を均一に行うことが困難になりやすいので、光学フィルム製造用原反フィルムの幅は7m以下であることが好ましい。 The width of the original film for producing an optical film of the present invention is not particularly limited, and can be determined according to the use of the produced optical film. In recent years, since the enlargement of screens of liquid crystal televisions and liquid crystal monitors has progressed, it is preferable for these applications to have a width of the original film for producing optical films of 3 m or more. On the other hand, if the width of the raw film for producing an optical film is too large, it is difficult to uniformly carry out uniaxial stretching itself when producing an optical film with an apparatus that has been put into practical use. The width of the anti-film is preferably 7 m or less.
 本発明の光学フィルム製造用原反フィルムの製造方法は特に限定されず、製膜後のフィルムの厚み及び幅がより均一になる製造方法を好ましく採用することができ、例えば、光学フィルム製造用原反フィルムを構成する上記したヒドロキシメチル基含有PVA及び必要に応じてさらに上記した可塑剤、添加剤及び後述する界面活性剤などのうちの1種または2種以上が液体媒体中に溶解した製膜原液や、ヒドロキシメチル基含有PVA及び必要に応じてさらに可塑剤、添加剤、界面活性剤及び液体媒体などのうちの1種または2種以上を含み、ヒドロキシメチル基含有PVAが溶融している製膜原液を用いて製造することができる。当該製膜原液が可塑剤、添加剤及び界面活性剤の少なくとも1種を含有する場合には、それらの成分が均一に混合されていることが好ましい。 The production method of the raw film for producing an optical film of the present invention is not particularly limited, and a production method in which the thickness and width of the film after film formation are more uniform can be preferably employed. Film formation in which one or two or more of the above-mentioned hydroxymethyl group-containing PVA constituting the anti-film and the above-described plasticizer, additive and surfactant described later are dissolved in a liquid medium as necessary. A raw material, a hydroxymethyl group-containing PVA and, if necessary, a plasticizer, an additive, a surfactant, a liquid medium, etc. It can be produced using a membrane stock solution. When the film-forming stock solution contains at least one of a plasticizer, an additive, and a surfactant, it is preferable that these components are uniformly mixed.
 製膜原液の調製に使用される上記液体媒体としては、例えば、水、ジメチルスルホキシド、ジメチルホルムアミド、ジメチルアセトアミド、N-メチルピロリドン、エチレングリコール、グリセリン、プロピレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、トリメチロールプロパン、エチレンジアミン、ジエチレントリアミンなどを挙げることができ、これらのうちの1種または2種以上を使用することができる。そのうちでも、環境に与える負荷や回収性の点から水が好ましい。 Examples of the liquid medium used for the preparation of the membrane forming stock solution include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol. , Trimethylolpropane, ethylenediamine, diethylenetriamine and the like, and one or more of them can be used. Among these, water is preferable from the viewpoint of environmental load and recoverability.
 製膜原液の揮発分率(製膜時に揮発や蒸発によって除去される液体媒体などの揮発性成分の製膜原液中における含有割合)は、製膜方法、製膜条件などによっても異なるが、一般的には、50~95質量%の範囲内であることが好ましく、55~90質量%の範囲内であることがより好ましく、60~85質量%の範囲内であることがさらに好ましい。製膜原液の揮発分率が50質量%以上であることにより、製膜原液の粘度が高くなり過ぎず、製膜原液調製時の濾過や脱泡が円滑に行われ、異物や欠点の少ないフィルムの製造が容易になる。一方、製膜原液の揮発分率が95質量%以下であることにより、製膜原液の濃度が低くなり過ぎず、工業的なフィルムの製造が容易になる。 The volatile fraction of the film-forming stock solution (content ratio in the film-forming stock solution of volatile components such as liquid media removed by volatilization or evaporation during film formation) varies depending on the film-forming method, film-forming conditions, etc. Specifically, it is preferably in the range of 50 to 95% by mass, more preferably in the range of 55 to 90% by mass, and still more preferably in the range of 60 to 85% by mass. The film-forming stock solution has a volatile content of 50% by mass or more, so that the viscosity of the film-forming stock solution does not become too high, and filtration and defoaming are smoothly performed during the preparation of the film-forming stock solution, and there are few foreign substances and defects. Is easy to manufacture. On the other hand, when the volatile fraction of the film-forming stock solution is 95% by mass or less, the concentration of the film-forming stock solution does not become too low, and industrial film production is facilitated.
 製膜原液は界面活性剤を含むことが好ましい。界面活性剤を含むことにより、製膜性が向上してフィルムの厚み斑の発生が抑制されると共に、製膜に使用する金属ロールやベルトからのフィルムの剥離が容易になる。界面活性剤を含む製膜原液から光学フィルム製造用原反フィルムを製造した場合には、当該フィルム中には界面活性剤が含有され得る。上記の界面活性剤の種類は特に限定されないが、金属ロールやベルトからの剥離性の観点などから、アニオン性界面活性剤またはノニオン性界面活性剤が好ましい。 The film forming stock solution preferably contains a surfactant. By including the surfactant, the film-forming property is improved and the occurrence of uneven thickness of the film is suppressed, and the film is easily peeled off from the metal roll or belt used for film formation. When a raw film for producing an optical film is produced from a film-forming stock solution containing a surfactant, the film may contain a surfactant. Although the kind of said surfactant is not specifically limited, From a viewpoint of the peelability from a metal roll or a belt, an anionic surfactant or a nonionic surfactant is preferable.
 アニオン性界面活性剤としては、例えば、ラウリン酸カリウム等のカルボン酸型;ポリオキシエチレンラウリルエーテル硫酸塩、オクチルサルフェート等の硫酸エステル型;ドデシルベンゼンスルホネート等のスルホン酸型などが好適である。 As the anionic surfactant, for example, a carboxylic acid type such as potassium laurate; a sulfuric acid ester type such as polyoxyethylene lauryl ether sulfate and octyl sulfate; and a sulfonic acid type such as dodecylbenzene sulfonate are suitable.
 ノニオン性界面活性剤としては、例えば、ポリオキシエチレンオレイルエーテル等のアルキルエーテル型;ポリオキシエチレンオクチルフェニルエーテル等のアルキルフェニルエーテル型;ポリオキシエチレンラウレート等のアルキルエステル型;ポリオキシエチレンラウリルアミノエーテル等のアルキルアミン型;ポリオキシエチレンラウリン酸アミド等のアルキルアミド型;ポリオキシエチレンポリオキシプロピレンエーテル等のポリプロピレングリコールエーテル型;ラウリン酸ジエタノールアミド、オレイン酸ジエタノールアミド等のアルカノールアミド型;ポリオキシアルキレンアリルフェニルエーテル等のアリルフェニルエーテル型などが好適である。 Nonionic surfactants include, for example, alkyl ether types such as polyoxyethylene oleyl ether; alkylphenyl ether types such as polyoxyethylene octylphenyl ether; alkyl ester types such as polyoxyethylene laurate; polyoxyethylene laurylamino Alkylamine type such as ether; alkylamide type such as polyoxyethylene lauric acid amide; polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether; alkanolamide type such as lauric acid diethanolamide and oleic acid diethanolamide; polyoxy An allyl phenyl ether type such as alkylene allyl phenyl ether is preferred.
 これらの界面活性剤は1種を単独で、または2種以上を組み合わせて使用することができる。 These surfactants can be used alone or in combination of two or more.
 製膜原液が界面活性剤を含む場合、その含有量は、製膜原液に含まれるヒドロキシメチル基含有PVA100質量部に対して、0.01~0.5質量部の範囲内であることが好ましく、0.02~0.3質量部の範囲内であることがより好ましく、0.05~0.1質量部の範囲内であることが特に好ましい。当該含有量が0.01質量部以上であることにより製膜性及び剥離性がより向上する。一方、当該含有量が0.5質量部以下であることにより、界面活性剤が光学フィルム製造用原反フィルムの表面にブリードアウトしてブロッキングが生じ、取り扱い性が低下することを抑制することができる。 When the film-forming stock solution contains a surfactant, the content thereof is preferably in the range of 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the hydroxymethyl group-containing PVA contained in the film-forming stock solution. The content is more preferably in the range of 0.02 to 0.3 parts by mass, and particularly preferably in the range of 0.05 to 0.1 parts by mass. When the said content is 0.01 mass part or more, film forming property and peelability improve more. On the other hand, when the content is 0.5 parts by mass or less, it is possible to suppress that the surfactant bleeds out to the surface of the optical film-producing raw film, resulting in blocking and deterioration in handling properties. it can.
 上記した製膜原液を用いて光学フィルム製造用原反フィルムを製膜する際の製膜方法としては、例えば、キャスト製膜法、押出製膜法、湿式製膜法、ゲル製膜法などが挙げられる。これらの製膜方法は1種のみを採用しても2種以上を組み合わせて採用してもよい。これらの製膜方法の中でもキャスト製膜法、押出製膜法が、厚み及び幅が均一で物性の良好な光学フィルム製造用原反フィルムが得られることから好ましい。製膜されたフィルムには必要に応じて乾燥や熱処理を行うことができる。 Examples of the film forming method for forming an optical film manufacturing raw film using the above film forming stock solution include a cast film forming method, an extrusion film forming method, a wet film forming method, and a gel film forming method. Can be mentioned. These film forming methods may be used alone or in combination of two or more. Among these film forming methods, the cast film forming method and the extrusion film forming method are preferable because a raw film for producing an optical film having a uniform thickness and width and good physical properties can be obtained. The formed film can be dried or heat-treated as necessary.
 本発明の光学フィルム製造用原反フィルムの具体的な製造方法の例としては、例えば、T型スリットダイ、ホッパープレート、I-ダイ、リップコーターダイ等を用いて、上記の製膜原液を最上流側に位置する回転する加熱した第1ロール(あるいはベルト)の周面上に均一に吐出または流延し、この第1ロール(あるいはベルト)の周面上に吐出または流延された膜の一方の面から揮発性成分を蒸発させて乾燥し、続いてその下流側に配置した1個または複数個の回転する加熱したロールの周面上でさらに乾燥するか、または熱風乾燥装置の中を通過させてさらに乾燥した後、巻き取り装置により巻き取る方法を工業的に好ましく採用することができる。加熱したロールによる乾燥と熱風乾燥装置による乾燥とは、適宜組み合わせて実施してもよい。 As a specific example of a method for producing a raw film for producing an optical film of the present invention, for example, using the T-type slit die, hopper plate, I-die, lip coater die, etc. The film discharged or cast uniformly on the peripheral surface of the rotating heated first roll (or belt) located on the upstream side and discharged or cast on the peripheral surface of the first roll (or belt) Volatile components are evaporated and dried from one side, and then further dried on the peripheral surface of one or more rotating heated rolls arranged downstream thereof, or in a hot air dryer After passing and further drying, the method of winding with a winding device can be preferably employed industrially. Drying with a heated roll and drying with a hot air dryer may be performed in an appropriate combination.
 本発明の光学フィルム製造用原反フィルムは、光学フィルムを製造するための原反フィルムとして使用される。このような光学フィルムとしては、例えば、偏光フィルムや位相差フィルムなどが挙げられ、偏光フィルムであることが好ましい。このような光学フィルムは、例えば、本発明の光学フィルム製造用原反フィルムを用いる方法であって一軸延伸する工程を有する方法により製造することができ、具体的には、本発明の光学フィルム製造用原反フィルムそのもの、あるいは、後述する膨潤処理等を施すなどして生じた本発明の光学フィルム製造用原反フィルムに由来するフィルム(以下、「本発明の光学フィルム製造用原反フィルム」と「本発明の光学フィルム製造用原反フィルムに由来するフィルム」をまとめて「本発明に基づくフィルム」と称することがある)を一軸延伸する工程を有する方法により製造することができる。 The original film for producing an optical film of the present invention is used as an original film for producing an optical film. Examples of such an optical film include a polarizing film and a retardation film, and a polarizing film is preferable. Such an optical film can be produced, for example, by a method using the raw film for producing an optical film of the present invention, and a method having a uniaxial stretching process. Specifically, the optical film of the present invention is produced. Film or the film derived from the original film for producing an optical film of the present invention (hereinafter referred to as “the original film for producing an optical film of the present invention”). The “films derived from the raw film for producing an optical film of the present invention” may be collectively referred to as “films according to the present invention”), and may be produced by a method having a step of uniaxially stretching.
 本発明の光学フィルム製造用原反フィルムを用いて偏光フィルムを製造する際の方法は特に制限されず、従来から採用されているいずれの方法を採用してもよい。このような方法としては、例えば、本発明に基づくフィルムに対して染色及び一軸延伸を施したり、染料を含有する本発明に基づくフィルムに対して一軸延伸を施したりする方法が挙げられる。偏光フィルムを製造するためのより具体的な方法としては、本発明に基づくフィルムに対して、膨潤、染色、一軸延伸、及び必要に応じてさらに、架橋処理、固定処理、乾燥、熱処理などを施す方法が挙げられる。この場合、膨潤、染色、架橋処理、一軸延伸、固定処理などの各処理の順序は特に制限されず、1つまたは2つ以上の処理を同時に行うこともできる。また、各処理の1つまたは2つ以上を2回またはそれ以上行うこともできる。 The method for producing a polarizing film using the original film for producing an optical film of the present invention is not particularly limited, and any conventionally employed method may be adopted. Examples of such a method include a method in which a film based on the present invention is dyed and uniaxially stretched, or a film based on the present invention containing a dye is uniaxially stretched. As a more specific method for producing a polarizing film, the film based on the present invention is subjected to swelling, dyeing, uniaxial stretching, and, if necessary, crosslinking treatment, fixing treatment, drying, heat treatment, etc. A method is mentioned. In this case, the order of each treatment such as swelling, dyeing, crosslinking treatment, uniaxial stretching, and fixing treatment is not particularly limited, and one or two or more treatments can be performed simultaneously. Also, one or more of each process can be performed twice or more.
 膨潤は、本発明に基づくフィルムを水に浸漬することにより行うことができる。水に浸漬する際の水の温度としては、20~40℃の範囲内であることが好ましく、22~38℃の範囲内であることがより好ましく、25~35℃の範囲内であることがさらに好ましい。また、水に浸漬する時間としては、例えば、0.1~5分間の範囲内であることが好ましく、0.5~3分間の範囲内であることがより好ましい。なお、水に浸漬する際の水は純水に限定されず、各種成分が溶解した水溶液であってもよいし、水と水性媒体との混合物であってもよい。 Swelling can be performed by immersing the film according to the present invention in water. The temperature of the water when immersed in water is preferably in the range of 20 to 40 ° C., more preferably in the range of 22 to 38 ° C., and preferably in the range of 25 to 35 ° C. Further preferred. The time for immersion in water is preferably in the range of 0.1 to 5 minutes, for example, and more preferably in the range of 0.5 to 3 minutes. In addition, the water at the time of immersing in water is not limited to pure water, The aqueous solution in which various components melt | dissolved may be sufficient, and the mixture of water and an aqueous medium may be sufficient.
 染色は、本発明に基づくフィルムに対して二色性色素を接触させることにより行うことができる。二色性色素としてはヨウ素系色素を用いるのが一般的である。染色の時期としては、一軸延伸前、一軸延伸時、一軸延伸後のいずれの段階であってもよい。染色はPVAフィルムを染色浴であるヨウ素-ヨウ化カリウムを含有する溶液(特に水溶液)中に浸漬させることにより行うのが一般的であり、本発明においてもこのような染色方法が好適に採用される。染色浴におけるヨウ素の濃度は0.01~0.5質量%の範囲内であることが好ましく、ヨウ化カリウムの濃度は0.01~10質量%の範囲内であることが好ましい。また、染色浴の温度は20~50℃、特に25~40℃とすることが好ましい。 Dyeing can be performed by bringing a dichroic dye into contact with the film according to the present invention. As the dichroic dye, an iodine dye is generally used. The dyeing time may be any stage before uniaxial stretching, during uniaxial stretching, or after uniaxial stretching. Dyeing is generally performed by immersing the PVA film in a solution (particularly an aqueous solution) containing iodine-potassium iodide which is a dyeing bath, and such a dyeing method is also suitably employed in the present invention. The The iodine concentration in the dyeing bath is preferably in the range of 0.01 to 0.5% by mass, and the potassium iodide concentration is preferably in the range of 0.01 to 10% by mass. The temperature of the dyeing bath is preferably 20 to 50 ° C., particularly 25 to 40 ° C.
 本発明に基づくフィルムに対して架橋処理を施すことで、高温で湿式延伸する際にヒドロキシメチル基含有PVAが水へ溶出するのをより効果的に防止することができる。この観点から架橋処理は二色性色素を接触させる処理の後であって一軸延伸の前に行うのが好ましい。架橋処理は、架橋剤を含む水溶液に本発明に基づくフィルムを浸漬することにより行うことができる。当該架橋剤としては、ホウ酸、ホウ砂等のホウ酸塩などのホウ素化合物の1種または2種以上を使用することができる。架橋剤を含む水溶液における架橋剤の濃度は1~15質量%の範囲内であることが好ましく、2~7質量%の範囲内であることがより好ましく、3~6質量%の範囲内であることがさらに好ましい。架橋剤の濃度が1~15質量%の範囲内にあることで十分な延伸性を維持することができる。架橋剤を含む水溶液はヨウ化カリウム等を含有してもよい。架橋剤を含む水溶液の温度は、20~50℃の範囲内、特に25~40℃の範囲内とすることが好ましい。当該温度を20~50℃の範囲内にすることで効率良く架橋することができる。 By subjecting the film based on the present invention to a crosslinking treatment, it is possible to more effectively prevent the hydroxymethyl group-containing PVA from eluting into water when wet-stretching at a high temperature. From this viewpoint, the crosslinking treatment is preferably performed after the treatment for bringing the dichroic dye into contact and before the uniaxial stretching. The crosslinking treatment can be performed by immersing the film according to the present invention in an aqueous solution containing a crosslinking agent. As the crosslinking agent, one or more of boron compounds such as boric acid and borate such as borax can be used. The concentration of the crosslinking agent in the aqueous solution containing the crosslinking agent is preferably in the range of 1 to 15% by mass, more preferably in the range of 2 to 7% by mass, and in the range of 3 to 6% by mass. More preferably. Sufficient stretchability can be maintained when the concentration of the crosslinking agent is in the range of 1 to 15% by mass. The aqueous solution containing a crosslinking agent may contain potassium iodide and the like. The temperature of the aqueous solution containing the crosslinking agent is preferably in the range of 20 to 50 ° C., particularly in the range of 25 to 40 ° C. By setting the temperature within the range of 20 to 50 ° C., crosslinking can be performed efficiently.
 本発明に基づくフィルムの一軸延伸は、湿式延伸法または乾式延伸法のいずれで行ってもよい。湿式延伸法の場合は、ホウ酸を含む水溶液中で行うこともできるし、上記した染色浴中や後述する固定処理浴中で行うこともできる。また乾式延伸法の場合は、室温のまま延伸を行ってもよいし、加熱しながら延伸してもよいし、吸水後の本発明に基づくフィルムを用いて空気中で行うこともできる。これらの中でも、幅方向に均一に延伸することができることから湿式延伸法が好ましく、ホウ酸を含む水溶液中で一軸延伸するのがより好ましい。ホウ酸水溶液中におけるホウ酸の濃度は0.5~6.0質量%の範囲内であることが好ましく、1.0~5.0質量%の範囲内であることがより好ましく、1.5~4.0質量%の範囲内であることが特に好ましい。また、ホウ酸水溶液はヨウ化カリウムを含有してもよく、ヨウ化カリウムの濃度は0.01~10質量%の範囲内にすることが好ましい。
 一軸延伸における延伸温度は、30~90℃の範囲内であることが好ましく、40~80℃の範囲内であることがより好ましく、50~70℃の範囲内であることが特に好ましい。
 また、一軸延伸における延伸倍率は、得られる偏光フィルムの偏光性能の点から6.6倍以上であることが好ましく、6.8倍以上であることがより好ましく、7.0倍以上であることが特に好ましい。延伸倍率の上限は特に制限されないが、延伸倍率は8倍以下であることが好ましい。
Uniaxial stretching of the film according to the present invention may be performed by either a wet stretching method or a dry stretching method. In the case of the wet stretching method, it can be carried out in an aqueous solution containing boric acid, or can be carried out in the dyeing bath described above or in a fixing treatment bath described later. In the case of the dry stretching method, the stretching may be performed at room temperature, may be performed while heating, or may be performed in the air using the film based on the present invention after water absorption. Among these, the wet stretching method is preferable because it can be uniformly stretched in the width direction, and uniaxial stretching is more preferable in an aqueous solution containing boric acid. The concentration of boric acid in the boric acid aqueous solution is preferably within the range of 0.5 to 6.0% by mass, more preferably within the range of 1.0 to 5.0% by mass, It is particularly preferably within the range of ˜4.0% by mass. The aqueous boric acid solution may contain potassium iodide, and the concentration of potassium iodide is preferably in the range of 0.01 to 10% by mass.
The stretching temperature in the uniaxial stretching is preferably in the range of 30 to 90 ° C, more preferably in the range of 40 to 80 ° C, and particularly preferably in the range of 50 to 70 ° C.
In addition, the draw ratio in uniaxial stretching is preferably 6.6 times or more, more preferably 6.8 times or more, and 7.0 times or more from the viewpoint of the polarizing performance of the obtained polarizing film. Is particularly preferred. The upper limit of the draw ratio is not particularly limited, but the draw ratio is preferably 8 times or less.
 長尺の本発明に基づくフィルムを一軸延伸する場合における一軸延伸の方向に特に制限はなく、長尺方向への一軸延伸や横一軸延伸を採用することができるが、偏光性能に優れる偏光フィルムが得られることから長尺方向への一軸延伸が好ましい。長尺方向への一軸延伸は、互いに平行な複数のロールを備える延伸装置を使用して、各ロール間の周速を変えることにより行うことができる。一方、横一軸延伸はテンター型延伸機を用いて行うことができる。 There is no particular limitation on the direction of uniaxial stretching in the case of uniaxially stretching a long film according to the present invention, and uniaxial stretching or lateral uniaxial stretching in the long direction can be adopted. Since it is obtained, uniaxial stretching in the longitudinal direction is preferable. Uniaxial stretching in the longitudinal direction can be performed by changing the peripheral speed between the rolls using a stretching apparatus including a plurality of rolls parallel to each other. On the other hand, lateral uniaxial stretching can be performed using a tenter type stretching machine.
 偏光フィルムの製造にあたっては、フィルムへの二色性色素(ヨウ素系色素等)の吸着を強固にするために固定処理を行うことが好ましい。固定処理に使用する固定処理浴としては、ホウ酸、硼砂等のホウ素化合物の1種または2種以上を含む水溶液を使用することができる。また、必要に応じて、固定処理浴中にヨウ素化合物や金属化合物を添加してもよい。固定処理浴におけるホウ素化合物の濃度は、一般に2~15質量%、特に3~10質量%程度であることが好ましい。当該濃度を2~15質量%の範囲内にすることで二色性色素の吸着をより強固にすることができる。固定処理浴の温度は、15~60℃、特に25~40℃であることが好ましい。 In the production of the polarizing film, it is preferable to perform a fixing treatment in order to strengthen the adsorption of the dichroic dye (iodine dye or the like) to the film. As the fixing treatment bath used for the fixing treatment, an aqueous solution containing one or more of boron compounds such as boric acid and borax can be used. Moreover, you may add an iodine compound and a metal compound in a fixed treatment bath as needed. The concentration of the boron compound in the fixing treatment bath is generally about 2 to 15% by mass, particularly about 3 to 10% by mass. By setting the concentration within the range of 2 to 15% by mass, the adsorption of the dichroic dye can be further strengthened. The temperature of the fixing treatment bath is preferably 15 to 60 ° C., particularly 25 to 40 ° C.
 乾燥の条件は特に制限されないが、30~150℃の範囲内、特に50~130℃の範囲内の温度で乾燥を行うことが好ましい。30~150℃の範囲内の温度で乾燥することで寸法安定性に優れる偏光フィルムが得られやすい。 Drying conditions are not particularly limited, but it is preferable to perform the drying at a temperature within the range of 30 to 150 ° C, particularly within the range of 50 to 130 ° C. A polarizing film excellent in dimensional stability can be easily obtained by drying at a temperature in the range of 30 to 150 ° C.
 本発明の光学フィルム製造用原反フィルムによれば収縮応力の低い光学フィルムを容易に製造することができる。得られる偏光フィルムの収縮応力は、温度20℃、相対湿度20%の条件下で調湿処理を施した後の偏光フィルムにおける長さ方向(偏光フィルム製造時の延伸方向)の収縮応力として、3.5N/mm以下であることが好ましい。当該収縮応力が3.5N/mm以下であることにより、LCDの反りが生じにくい偏光フィルムとなる。LCDの反りの観点から、当該収縮応力は、3.2N/mm以下であることがより好ましく、3N/mm以下であることがさらに好ましく、2.7N/mm以下であることが特に好ましい。当該収縮応力の下限に特に制限はないが、当該収縮応力は、例えば1N/mm以上、さらには2N/mm以上であってもよい。 According to the raw film for producing an optical film of the present invention, an optical film having a low shrinkage stress can be easily produced. The contraction stress of the obtained polarizing film is 3 as the contraction stress in the length direction (stretching direction at the time of manufacturing the polarizing film) in the polarizing film after the humidity control is performed under the conditions of a temperature of 20 ° C. and a relative humidity of 20%. It is preferably 5 N / mm 2 or less. When the shrinkage stress is 3.5 N / mm 2 or less, the polarizing film is less likely to warp the LCD. In view of the LCD of warpage, the shrinkage stress is more preferably 3.2 N / mm 2 or less, still more preferably 3N / mm 2 or less, particularly not less 2.7 N / mm 2 or less preferable. There is no particular limitation on the lower limit of the shrinkage stress, the shrinkage stress, for example 1N / mm 2 or more, or even at 2N / mm 2 or more.
 上記の収縮応力は、次のようにして測定することができる。すなわち、測定対象となる偏光フィルムのサンプル(長さ12cm×幅1.5cm)に対して、まず、温度20℃、相対湿度20%の条件下で調湿処理を施す。ここで当該調湿処理は収縮応力測定のために行う。当該調湿処理をしない場合には、通常、収縮応力の値が大きくなるが、本処理をすることにより、収縮応力の値を小さくすることができるとともに、より一層正確な値を得ることができる。上記調湿処理を施した後、このサンプルをチャック間5cmで長さ方向を固定し、次いで、温度40℃、相対湿度5%の条件下で長さ方向に延伸し、張力が2Nに達したときに延伸を停止して保持し、その状態で80℃に昇温して4時間経過した際の長さ方向の収縮応力(N/mm)を求める。当該収縮応力は、より具体的には実施例において後述する方法により測定することができる。 The shrinkage stress can be measured as follows. That is, a humidity control process is first performed on a polarizing film sample (length 12 cm × width 1.5 cm) to be measured under conditions of a temperature of 20 ° C. and a relative humidity of 20%. Here, the humidity control process is performed to measure the shrinkage stress. When the humidity control process is not performed, the value of the contraction stress usually increases, but by performing this process, the value of the contraction stress can be decreased and a more accurate value can be obtained. . After performing the humidity control treatment, the length direction of this sample was fixed at 5 cm between chucks, and then stretched in the length direction under conditions of a temperature of 40 ° C. and a relative humidity of 5%, and the tension reached 2N. The stretching is sometimes stopped and held, and in that state, the shrinkage stress (N / mm 2 ) in the length direction when the temperature is raised to 80 ° C. and 4 hours elapses is obtained. More specifically, the shrinkage stress can be measured by the method described later in the examples.
 以上のようにして得られた偏光フィルムは、通常、その両面または片面に、光学的に透明で且つ機械的強度を有する保護膜を貼り合わせて偏光板にして使用される。保護膜としては、三酢酸セルロース(TAC)フィルム、シクロオレフィンポリマー(COP)フィルム、酢酸・酪酸セルロース(CAB)フィルム、アクリル系フィルム、ポリエステル系フィルムなどが使用される。また、貼り合わせのための接着剤としては、PVA系接着剤、ウレタン系接着剤、アクリレート系紫外線硬化型接着剤などを挙げることができる。 The polarizing film obtained as described above is usually used as a polarizing plate by attaching an optically transparent protective film having mechanical strength to both sides or one side. As the protective film, a cellulose triacetate (TAC) film, a cycloolefin polymer (COP) film, an acetic acid / cellulose butyrate (CAB) film, an acrylic film, a polyester film, or the like is used. Examples of the adhesive for bonding include PVA adhesives, urethane adhesives, acrylate ultraviolet curable adhesives, and the like.
 上記のようにして得られた偏光板は、アクリル系等の粘着剤をコートした後、ガラス基板に貼り合わせてLCDの部品として使用することができる。同時に位相差フィルムや視野角向上フィルム、輝度向上フィルム等と貼り合わせてもよい。 The polarizing plate obtained as described above can be used as an LCD component after being coated with an acrylic adhesive or the like and bonded to a glass substrate. At the same time, it may be bonded to a retardation film, a viewing angle improving film, a brightness improving film, or the like.
 以下、実施例により本発明をより詳細に説明するが、本発明はこれらの実施例により何ら限定されるものではない。なお、以下の実施例及び比較例において採用された各測定または評価方法を以下に示す。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, each measurement or evaluation method employ | adopted in the following examples and comparative examples is shown below.
PVAの一次構造
 以下の実施例及び比較例で使用したPVA(実施例におけるヒドロキシメチル基含有PVAや比較例における各種変性PVA)の一次構造は、400MHz H-NMRを用いて分析した。H-NMR測定時の溶媒は重水素化DMSOを用いた。
Primary structure of PVA The primary structure of PVA (hydroxymethyl group-containing PVA in Examples and various modified PVA in Comparative Examples) used in the following Examples and Comparative Examples was analyzed using 400 MHz 1 H-NMR. Deuterated DMSO was used as a solvent for the 1 H-NMR measurement.
光学フィルム製造用原反フィルムの膨潤度
 以下の実施例または比較例で得られた光学フィルム製造用原反フィルムを1.5gとなるようにカットし、30℃の蒸留水中に30分間浸漬した。30分間浸漬後に当該フィルムを取り出し、ろ紙で表面の水を取り、質量「N」を求めた。続いてそのフィルムを105℃の乾燥機で16時間乾燥した後、質量「M」を求めた。得られた質量「N」及び「M」から、下記式(3)により光学フィルム製造用原反フィルムの膨潤度を算出した。
   膨潤度(%) = 100 × N/M   (3)
 
The degree of swelling of the raw film for optical film production The raw film for optical film production obtained in the following examples or comparative examples was cut to 1.5 g and immersed in distilled water at 30 ° C. for 30 minutes. After immersion for 30 minutes, the film was taken out, the surface water was taken out with a filter paper, and the mass “N” was determined. Subsequently, the film was dried with a dryer at 105 ° C. for 16 hours, and then the mass “M” was determined. From the obtained masses “N” and “M”, the degree of swelling of the raw film for optical film production was calculated by the following formula (3).
Swelling degree (%) = 100 × N / M (3)
光学フィルム製造用原反フィルムの延伸性
 以下の実施例または比較例で得られた光学フィルム製造用原反フィルムの幅方向中央部から、幅5cm×長さ5cmの範囲が一軸延伸できるように幅5cm×長さ8cmのサンプルをカットした。このサンプルを30℃の純水に浸漬しつつ1.5倍に長さ方向に一軸延伸した。続いてヨウ素を0.03質量%及びヨウ化カリウムを3.0質量%の割合で含有する水溶液(染色浴)(温度30℃)に60秒間浸漬しつつ1.6倍(全体で2.4倍)に長さ方向に一軸延伸してヨウ素を吸着させた。次いで、ホウ酸を3質量%及びヨウ化カリウムを3質量%の割合で含有する水溶液(架橋浴)(温度30℃)に浸漬しつつ1.1倍(全体で2.6倍)に長さ方向に一軸延伸した。さらにホウ酸を4質量%及びヨウ化カリウムを6質量%の割合で含有する水溶液(延伸浴)に浸漬しつつ、切断するまで長さ方向に一軸延伸し、延伸前の光学フィルム製造用原反フィルムの長さに対する切断時の長さの倍率を限界延伸倍率とした。ただし、延伸浴の温度については、適当な温度から1℃ずつ変更して限界延伸倍率を測定し、限界延伸倍率が最も高くなる温度を選択した。
Stretchability of the optical film production raw film From the center in the width direction of the optical film production raw film obtained in the following examples or comparative examples, the width of the width 5 cm × length 5 cm is uniaxially stretched. A 5 cm × 8 cm long sample was cut. This sample was uniaxially stretched in the length direction by a factor of 1.5 while being immersed in pure water at 30 ° C. Subsequently, while being immersed in an aqueous solution (dyeing bath) (temperature 30 ° C.) containing 0.03% by mass of iodine and 3.0% by mass of potassium iodide for 60 seconds, the ratio is 1.6 times (2.4 in total). Uniaxially stretching in the length direction to adsorb iodine. Next, the length was 1.1 times (2.6 times in total) while being immersed in an aqueous solution (crosslinking bath) (temperature 30 ° C.) containing 3% by weight of boric acid and 3% by weight of potassium iodide. Uniaxially stretched in the direction. Further, while being immersed in an aqueous solution (stretching bath) containing 4% by mass of boric acid and 6% by mass of potassium iodide, the film is uniaxially stretched in the length direction until it is cut, and the raw film for producing an optical film before stretching. The ratio of the length at the time of cutting with respect to the length of the film was defined as the limit stretch ratio. However, the temperature of the stretching bath was changed by 1 ° C. from an appropriate temperature, the limiting stretching ratio was measured, and the temperature at which the limiting stretching ratio was the highest was selected.
偏光フィルムの光学特性(二色性比)
(1)透過率Tsの測定
 以下の実施例または比較例で得られた偏光フィルムの中央部から、偏光フィルムの長さ方向に2cmのサンプルを2枚採取し、積分球付き分光光度計(日本分光株式会社製「V7100」)を用いて、JIS Z 8722(物体色の測定方法)に準拠し、C光源、2°視野の可視光領域の視感度補正を行い、1枚のサンプルについて、長さ方向に対して+45°傾けた場合の光の透過率と-45°傾けた場合の光の透過率を測定して、それらの平均値Ts1(%)を求めた。もう1枚のサンプルについても同様にして、+45°傾けた場合の光の透過率と-45°傾けた場合の光の透過率を測定して、それらの平均値Ts2(%)を求めた。下記式(4)によりTs1とTs2を平均し、偏光フィルムの透過率Ts(%)とした。
   Ts = (Ts1+Ts2)/2   (4)
 
Optical properties of polarizing film (dichroic ratio)
(1) Measurement of transmittance Ts From the central part of the polarizing film obtained in the following examples or comparative examples, two 2 cm samples were taken in the length direction of the polarizing film, and a spectrophotometer with an integrating sphere (Japan) Using “V7100” manufactured by Spectroscopic Co., Ltd., in accordance with JIS Z 8722 (measuring method of object color), the visibility of the visible light region of the C light source and 2 ° field of view is corrected. The light transmittance when tilted by + 45 ° with respect to the vertical direction and the light transmittance when tilted by −45 ° were measured, and an average value Ts1 (%) thereof was obtained. Similarly, with respect to the other sample, the light transmittance when tilted by + 45 ° and the light transmittance when tilted by −45 ° were measured, and an average value Ts2 (%) thereof was obtained. Ts1 and Ts2 were averaged by the following formula (4) to obtain the transmittance Ts (%) of the polarizing film.
Ts = (Ts1 + Ts2) / 2 (4)
(2)偏光度Vの測定
 上記透過率Tsの測定で採取した2枚のサンプルを、その長さ方向が平行になるように重ねた場合の光の透過率T∥(%)、長さ方向が直交するように重ねた場合の光の透過率T⊥(%)を、上記「(1)透過率Tsの測定」の場合と同様にして測定し、下記式(5)により偏光度V(%)を求めた。
   V = {(T∥-T⊥)/(T∥+T⊥)}1/2×100   (5)
 
(2) Measurement of degree of polarization V Light transmittance T∥ (%) and length direction when two samples collected in the measurement of transmittance Ts are stacked so that their length directions are parallel. Are measured in the same manner as in the case of “(1) Measurement of transmittance Ts”, and the degree of polarization V ( %).
V = {(T∥−T⊥) / (T∥ + T⊥)} 1/2 × 100 (5)
(3)透過率44%時の二色性比の算出
 以下の各実施例及び比較例において、染色浴におけるヨウ素の濃度を0.02~0.04質量%及びヨウ化カリウムの濃度を2.0~4.0質量%の各範囲内で4回変更(ただし、ヨウ素の濃度:ヨウ化カリウムの濃度=1:100とする)して同様の操作を行い、各実施例または比較例で製造した偏光フィルムとは二色性色素の吸着量の異なる4枚の偏光フィルムを製造した。これら4枚の偏光フィルムのそれぞれについて上記した方法で透過率Ts(%)及び偏光度V(%)を求め、各実施例及び比較例毎に、透過率Ts(%)を横軸、偏光度V(%)を縦軸として、各実施例または比較例で得られた偏光フィルムの透過率Ts(%)及び偏光度V(%)に基づく1点も含めた合計5点をグラフにプロットして近似曲線を求め、当該近似曲線から、透過率Ts(%)が44%であるときの偏光度V44(%)を求めた。
 得られた偏光度V44(%)から、下記式(6)により透過率44%時の二色性比を求めて、偏光性能の指標とした。なお、二色性比が高いほど偏光フィルムの光学特性は良好であり、二色性比が66以上の場合を「○」(良好)と判定し、66未満の場合を「×」(不良)と判定した。
   透過率44%時の二色性比 = log(44/100-44/100×V44/100)/log(44/100+44/100×V44/100)   (6)
 
(3) Calculation of dichroic ratio when transmittance is 44% In each of the following Examples and Comparative Examples, the iodine concentration in the dyeing bath is 0.02 to 0.04% by mass, and the potassium iodide concentration is 2. The same operation was carried out by changing 4 times within the range of 0 to 4.0% by mass (however, the concentration of iodine: concentration of potassium iodide = 1: 100). Four polarizing films having different dichroic dye adsorption amounts were produced. For each of these four polarizing films, the transmittance Ts (%) and the degree of polarization V (%) were determined by the method described above, and the transmittance Ts (%) was plotted on the horizontal axis and the degree of polarization for each example and comparative example. With V (%) as the vertical axis, a total of 5 points including one point based on the transmittance Ts (%) and the degree of polarization V (%) of the polarizing film obtained in each example or comparative example are plotted on a graph. Thus, an approximate curve was obtained, and from the approximate curve, the degree of polarization V 44 (%) when the transmittance Ts (%) was 44% was obtained.
From the obtained degree of polarization V 44 (%), the dichroic ratio at a transmittance of 44% was determined by the following formula (6) and used as an index of polarization performance. In addition, the higher the dichroic ratio, the better the optical properties of the polarizing film. When the dichroic ratio is 66 or more, it is determined as “◯” (good), and when it is less than 66, “X” (defect) It was determined.
Dichroic ratio when the transmittance 44% = log (44 / 100-44 / 100 × V 44/100) / log (44/100 + 44/100 × V 44/100) (6)
偏光フィルムの色相(平行b値)
 上記の「偏光フィルムの光学特性(二色性比)」において、二色性色素の吸着量の異なる4枚の偏光フィルムの偏光度Vを求める際に、透過率T∥(%)及び透過率T⊥(%)測定時にLab色空間を測定し、透過率T∥(%)の測定時のb値を平行b値とし、透過率T⊥(%)の測定時のb値を直交b値とした。各実施例及び比較例毎に、平行b値を横軸、直交b値を縦軸として、各実施例または比較例で得られた偏光フィルムの平行b値及び直交b値に基づく1点も含めた合計5点をグラフにプロットして近似曲線を求め、当該近似曲線から、直交b値が-4であるときの平行b値を求めた。なお、平行b値が0に近いほど偏光フィルムの色相は良好であり、平行b値が2.2未満の場合を「○」(良好)と判定し、2.2以上の場合を「×」(不良)と判定した。
Color of polarizing film (parallel b value)
In the above-mentioned “optical properties of the polarizing film (dichroic ratio)”, the transmittance T∥ (%) and the transmittance are obtained when the degree of polarization V of the four polarizing films having different dichroic dye adsorption amounts is obtained. Lab color space is measured when measuring T⊥ (%), b value when measuring transmittance T∥ (%) is a parallel b value, and b value when measuring transmittance T⊥ (%) is an orthogonal b value. It was. For each example and comparative example, including the parallel b value as the horizontal axis and the orthogonal b value as the vertical axis, including one point based on the parallel b value and orthogonal b value of the polarizing film obtained in each example or comparative example A total of 5 points were plotted on a graph to obtain an approximate curve, and a parallel b value when the orthogonal b value was −4 was obtained from the approximate curve. In addition, the hue of the polarizing film is better as the parallel b value is closer to 0, and the case where the parallel b value is less than 2.2 is determined as “◯” (good), and the case where the parallel b value is 2.2 or more is determined as “x”. (Defect) was determined.
偏光フィルムの耐久性(吸光度残存率)
 各実施例または比較例毎に、上記の「偏光フィルムの光学特性(二色性比)」において製造した二色性色素の吸着量の異なる4枚の偏光フィルム及び各実施例または比較例で得られた偏光フィルムの合計5枚の偏光フィルムの中から、透過率が44~45%の範囲にあり、且つ、透過率T⊥(%)測定時に求めた波長610nmでの吸光度(直交吸光度)が2.95~3.05である偏光フィルムを1枚選定した。
 その偏光フィルムを60℃、90%RHの環境下で4時間暴露し、初期の波長610nmでの直交吸光度をA0h及び4時間暴露後の波長610nmでの直交吸光度をA4hとして、下記式(7)により求めた直交吸光度の残存率(吸光度残存率)D(%)を偏光フィルムの耐久性として評価した。なお、吸光度残存率が高いほど偏光フィルムの耐久性は良好であり、吸光度残存率が33%以上の場合を「○」(良好)と判定し、33%未満の場合を「×」(不良)と判定した。
   D(%)=100 × A4h/A0h   (7)
 
Durability of polarizing film (absorbance remaining rate)
For each example or comparative example, the four polarizing films produced in the above-mentioned “Optical characteristics of the polarizing film (dichroic ratio)” with different amounts of adsorption of the dichroic dye, and each example or comparative example were obtained. The absorbance (orthogonal absorbance) at a wavelength of 610 nm obtained when the transmittance was in the range of 44 to 45% and the transmittance T⊥ (%) was measured out of the total of five polarizing films obtained. One polarizing film of 2.95 to 3.05 was selected.
The polarizing film was exposed for 4 hours in an environment of 60 ° C. and 90% RH, and the orthogonal absorbance at an initial wavelength of 610 nm was A 0h and the orthogonal absorbance at a wavelength of 610 nm after exposure for 4 hours was A 4h. The residual rate of orthogonal absorbance (absorbance residual rate) D (%) determined by 7) was evaluated as the durability of the polarizing film. The higher the residual absorbance rate, the better the durability of the polarizing film. When the residual absorbance rate is 33% or more, it is judged as “◯” (good), and when it is less than 33%, “x” (bad). It was determined.
D (%) = 100 × A 4h / A 0h (7)
偏光フィルムの収縮応力
 以下の実施例または比較例で得られた偏光フィルムの中央部から、偏光フィルムの長さ方向に12cm、幅方向に1.5cmの矩形のサンプルを採取し、温度20℃、相対湿度20%の条件下で16時間調湿した。次いでこのサンプルをチャック間5cmで長さ方向が固定されるように株式会社島津製作所製のオートグラフ「AG-X」に固定し、温度40℃、相対湿度5%の条件下、1mm/分の速度で長さ方向に延伸し、張力が2Nに達したときに延伸を停止して保持し、その状態で80℃に昇温して4時間後の張力を測定し、これをフィルムの断面積(単位:mm)で除すことにより、その偏光フィルムの収縮応力(長さ方向の収縮応力)を求めた。収縮応力が3.5N/mm以下の場合を「○」(良好)と判定し、3.5N/mmを超える場合を「×」(不良)と判定した。
From the central part of the polarizing film obtained in Examples or Comparative Examples below the contraction stress of the polarizing film, a rectangular sample of 12 cm in the length direction of the polarizing film and 1.5 cm in the width direction is collected, and the temperature is 20 ° C. The humidity was adjusted for 16 hours under the condition of a relative humidity of 20%. Next, this sample was fixed to an autograph “AG-X” manufactured by Shimadzu Corporation so that the length direction was fixed at 5 cm between chucks, and 1 mm / min under conditions of a temperature of 40 ° C. and a relative humidity of 5%. The film was stretched in the length direction at a speed, and when the tension reached 2N, the stretching was stopped and held, and in that state, the temperature was raised to 80 ° C., and the tension after 4 hours was measured. By dividing by (unit: mm 2 ), the contraction stress (contraction stress in the length direction) of the polarizing film was determined. A case where the shrinkage stress was 3.5 N / mm 2 or less was determined as “◯” (good), and a case where the shrinkage stress exceeded 3.5 N / mm 2 was determined as “x” (defective).
[実施例1]
(1)変性PVAとして酢酸ビニルと酢酸2-メチル-2-プロペニルとの共重合体をけん化することにより得られた表1に示すヒドロキシメチル基含有PVA100質量部、可塑剤としてグリセリン10質量部、及び界面活性剤としてポリオキシエチレンラウリルエーテル硫酸ナトリウム0.1質量部を含み、変性PVAの含有率が10質量%である水溶液を製膜原液として用いて、これを80℃の金属ロール上で乾燥し、得られたフィルムを熱風乾燥機中で所定の温度で1分間熱処理をすることにより膨潤度を200%に調整して、厚みが30μmの光学フィルム製造用原反フィルムを製造した。
 得られた光学フィルム製造用原反フィルムを用いて、上記した方法により延伸性を評価した。結果を表1に示した。
[Example 1]
(1) 100 parts by mass of a hydroxymethyl group-containing PVA shown in Table 1 obtained by saponifying a copolymer of vinyl acetate and 2-methyl-2-propenyl acetate as a modified PVA, 10 parts by mass of glycerin as a plasticizer, And an aqueous solution containing 0.1 part by mass of polyoxyethylene lauryl ether sodium sulfate as a surfactant and having a modified PVA content of 10% by mass as a film-forming stock solution, and drying it on a metal roll at 80 ° C. Then, the degree of swelling was adjusted to 200% by subjecting the obtained film to a heat treatment at a predetermined temperature for 1 minute in a hot air dryer to produce an original film for producing an optical film having a thickness of 30 μm.
The stretchability was evaluated by the above-described method using the obtained optical film for optical film production. The results are shown in Table 1.
(2)上記(1)で得られた光学フィルム製造用原反フィルムの幅方向中央部から、幅5cm×長さ5cmの範囲が一軸延伸できるように幅5cm×長さ8cmのサンプルをカットした。このサンプルを30℃の純水に浸漬しつつ1.5倍に長さ方向に一軸延伸した。続いてヨウ素を0.03質量%及びヨウ化カリウムを3.0質量%の割合で含有する水溶液(染色浴)(温度30℃)に60秒間浸漬しつつ1.6倍(全体で2.4倍)に長さ方向に一軸延伸してヨウ素を吸着させた。次いで、ホウ酸を3質量%及びヨウ化カリウムを3質量%の割合で含有する水溶液(架橋浴)(温度30℃)に浸漬しつつ1.1倍(全体で2.6倍)に長さ方向に一軸延伸した。さらにホウ酸を4質量%及びヨウ化カリウムを6質量%の割合で含有する水溶液(延伸浴)(上記「光学フィルム製造用原反フィルムの延伸性」で求めた限界延伸倍率が最も高くなる温度)に浸漬しつつ、限界延伸倍率よりも0.2倍低い倍率まで長さ方向に一軸延伸した。その後、ヨウ化カリウムを3質量%の割合で含有する水溶液(洗浄浴)(温度30℃)に5秒間浸漬し、最後に60℃で4分間乾燥して偏光フィルムを製造した。
 得られた偏光フィルムを用いて、上記した方法により偏光フィルムの光学特性(二色性比)、色相(平行b値)、耐久性及び収縮応力を評価した。結果を表1に示した。
(2) A sample having a width of 5 cm and a length of 8 cm was cut from the central portion in the width direction of the original film for producing an optical film obtained in (1) so that a range of width 5 cm × length 5 cm could be uniaxially stretched. . This sample was uniaxially stretched in the length direction by a factor of 1.5 while being immersed in pure water at 30 ° C. Subsequently, while being immersed in an aqueous solution (dyeing bath) (temperature 30 ° C.) containing 0.03% by mass of iodine and 3.0% by mass of potassium iodide for 60 seconds, the ratio is 1.6 times (2.4 in total). Uniaxially stretching in the length direction to adsorb iodine. Next, the length was 1.1 times (2.6 times in total) while being immersed in an aqueous solution (crosslinking bath) (temperature 30 ° C.) containing 3% by weight of boric acid and 3% by weight of potassium iodide. Uniaxially stretched in the direction. Further, an aqueous solution (stretching bath) containing 4% by mass of boric acid and 6% by mass of potassium iodide (a temperature at which the limit stretching ratio determined in the above “stretchability of the raw film for producing optical film” becomes the highest) ) Was uniaxially stretched in the length direction to a magnification 0.2 times lower than the limit draw ratio. Thereafter, it was immersed in an aqueous solution (cleaning bath) containing 3% by mass of potassium iodide (temperature 30 ° C.) for 5 seconds, and finally dried at 60 ° C. for 4 minutes to produce a polarizing film.
Using the obtained polarizing film, the optical properties (dichroic ratio), hue (parallel b value), durability and shrinkage stress of the polarizing film were evaluated by the method described above. The results are shown in Table 1.
[実施例2~5]
 実施例1において、変性PVAとして酢酸ビニルと酢酸2-メチル-2-プロペニルとの共重合体をけん化することにより得られた表1に示すヒドロキシメチル基含有PVA(実施例2~5)を用いたこと以外は、実施例1と同様にして光学フィルム製造用原反フィルム及び偏光フィルムを製造して、各測定または評価を行った。結果を表1に示した。
[Examples 2 to 5]
In Example 1, hydroxymethyl group-containing PVA (Examples 2 to 5) shown in Table 1 obtained by saponifying a copolymer of vinyl acetate and 2-methyl-2-propenyl acetate as a modified PVA was used. Except for the above, a raw film for producing an optical film and a polarizing film were produced in the same manner as in Example 1, and each measurement or evaluation was performed. The results are shown in Table 1.
[比較例1~4および参考例1]
 実施例1において、変性PVAの代わりに酢酸ビニルの単独重合体をけん化することにより得られた表1に示す未変性PVA(比較例1);変性PVAとして酢酸ビニルと酢酸2-メチル-2-プロペニルとの共重合体をけん化することにより得られた表1に示すヒドロキシメチル基含有PVA(比較例2);変性PVAとして酢酸ビニルと3,4-ジアセトキシ-1-ブテンとの共重合体をけん化することにより得られた表1に示す変性PVA(比較例3);変性PVAとして酢酸ビニルとイタコン酸との共重合体をけん化することにより得られた表1に示す変性PVA(比較例4);または、変性PVAとして酢酸ビニルと7-アセトキシ-1-ヘプテンとの共重合体をけん化することにより得られた表1に示す変性PVA(参考例1)をそれぞれ用いたこと以外は、実施例1と同様にして光学フィルム製造用原反フィルム及び偏光フィルムを製造して、各測定または評価を行った。結果を表1に示した。
[Comparative Examples 1 to 4 and Reference Example 1]
In Example 1, unmodified PVA shown in Table 1 obtained by saponifying a homopolymer of vinyl acetate instead of modified PVA (Comparative Example 1); vinyl acetate and 2-methyl-2-acetate as modified PVA Hydroxymethyl group-containing PVA shown in Table 1 obtained by saponifying a copolymer with propenyl (Comparative Example 2); As a modified PVA, a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene was used. Modified PVA shown in Table 1 obtained by saponification (Comparative Example 3); Modified PVA shown in Table 1 obtained by saponifying a copolymer of vinyl acetate and itaconic acid as modified PVA (Comparative Example 4) Or modified PVA shown in Table 1 obtained by saponifying a copolymer of vinyl acetate and 7-acetoxy-1-heptene as modified PVA (Reference Example 1) Except for the use respectively, to produce a raw film and polarizing film for an optical film prepared in the same manner as in Example 1 were each measured or evaluated. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
 以上の結果から明らかなように、本発明の規程を満たす実施例1~5の光学フィルム製造用原反フィルムによれば、光学特性、色相及び耐久性のいずれにも優れる収縮応力の低い光学フィルムを容易に製造できることが分かる。 As is clear from the above results, according to the raw film for producing an optical film of Examples 1 to 5 satisfying the regulations of the present invention, the optical film having a low shrinkage stress, which is excellent in all of optical characteristics, hue and durability. It can be seen that can be easily manufactured.

Claims (8)

  1.  下記式(1)で示される構造単位の含有率が0.1~1.9モル%であるヒドロキシメチル基含有ビニルアルコール系重合体を含む、光学フィルム製造用原反フィルム。
    Figure JPOXMLDOC01-appb-C000001
    [式中、Rは炭素数1~3のアルキル基を示す。]
    A raw film for producing an optical film comprising a hydroxymethyl group-containing vinyl alcohol polymer having a content of a structural unit represented by the following formula (1) of 0.1 to 1.9 mol%.
    Figure JPOXMLDOC01-appb-C000001
    [Wherein R 1 represents an alkyl group having 1 to 3 carbon atoms. ]
  2.  前記ヒドロキシメチル基含有ビニルアルコール系重合体の重合度が2,000を超える、請求項1に記載の光学フィルム製造用原反フィルム。 The raw film for producing an optical film according to claim 1, wherein the degree of polymerization of the hydroxymethyl group-containing vinyl alcohol polymer exceeds 2,000.
  3.  前記ヒドロキシメチル基含有ビニルアルコール系重合体のけん化度が95モル%以上である、請求項1または2に記載の光学フィルム製造用原反フィルム。 The raw film for producing an optical film according to claim 1 or 2, wherein the hydroxymethyl group-containing vinyl alcohol polymer has a saponification degree of 95 mol% or more.
  4.  前記ヒドロキシメチル基含有ビニルアルコール系重合体の1,2-グリコール結合量が1.5モル%以下である、請求項1~3のいずれか1項に記載の光学フィルム製造用原反フィルム。 The raw film for producing an optical film according to any one of claims 1 to 3, wherein the 1,2-glycol bond amount of the hydroxymethyl group-containing vinyl alcohol polymer is 1.5 mol% or less.
  5.  前記式(1)で示される構造単位のRがメチル基である、請求項1~4のいずれか1項に記載の光学フィルム製造用原反フィルム。 5. The raw film for producing an optical film according to claim 1 , wherein R 1 of the structural unit represented by the formula (1) is a methyl group.
  6.  厚みが60μm以下である、請求項1~5のいずれか1項に記載の光学フィルム製造用原反フィルム。 6. The raw film for producing an optical film according to claim 1, wherein the thickness is 60 μm or less.
  7.  偏光フィルム製造用原反フィルムである、請求項1~6のいずれか1項に記載の光学フィルム製造用原反フィルム。 The raw film for producing an optical film according to any one of claims 1 to 6, which is a raw film for producing a polarizing film.
  8.  請求項1~7のいずれか1項に記載の光学フィルム製造用原反フィルムを用いる光学フィルムの製造方法であって一軸延伸する工程を有する製造方法。 A method for producing an optical film using the raw film for producing an optical film according to any one of claims 1 to 7, wherein the method comprises a step of uniaxial stretching.
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