Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
  • B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F216/00—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
  • C08F216/02—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 by an alcohol radical
  • C08F216/04—Acyclic compounds
  • C08F216/06—Polyvinyl alcohol ; Vinyl alcohol
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/12—Hydrolysis
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
  • C08L29/02—Homopolymers or copolymers of unsaturated alcohols
  • C08L29/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/30—Polarising elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/30—Polarising elements
  • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
  • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/133528—Polarisers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2329/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
  • C08J2329/02—Homopolymers or copolymers of unsaturated alcohols
  • C08J2329/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids

Definitions

• the present invention relates to a specific film useful as a raw film for producing an optical film such as a polarizing film, which includes a hydroxymethyl group-containing vinyl alcohol polymer having a 1,3-diol structure, and the same.
• the present invention relates to a method for producing an optical film.
• 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 cellulose triacetate (TAC) film is bonded to the surface of the polarizing film in order to prevent the polarizing film from fading or to prevent the polarizing film from shrinking.
• TAC cellulose triacetate
• a vinyl alcohol polymer film (hereinafter, “vinyl alcohol polymer” may be referred to as “PVA”) is uniaxially stretched into a matrix formed with an iodine dye (I 3 - and I 5 -, etc.) or a dichroic dye such as dichroic organic dyes has become mainstream those adsorbed.
• 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.
• reduction in thickness and weight has been demanded.
• thinning of each member of the LCD is progressing, and there is a concern that the function of preventing the contraction of the polarizing film is lowered with the thinning of the protective film of the polarizing plate. Accordingly, there is a demand for a polarizing film that has high degree of polarization and transparency, excellent optical characteristics, and reduced shrinkage.
• 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 it has excellent processability and adsorption processability of dichroic substances, and exhibits good optical performance (see Patent Document 1 and the like).
• a specific optical PVA film containing a specific PVA containing a 1,2-glycol bond in the side chain is excellent in optical properties and stretchability (see Patent Document 2).
• an object of the present invention is to provide a film capable of easily producing an optical film excellent in optical properties and shrinkage reduction, and a method for producing an optical film using the film.
• the present invention includes a hydroxymethyl group-containing PVA containing a specific structural unit having a 1,3-diol structure in the main chain, and the softening point is within a specific range.
• the present inventors have found that the above-mentioned problems can be solved by a certain film, and have further studied based on the knowledge to complete the present invention.
• the present invention [1] A film containing a vinyl alcohol unit and a hydroxymethyl group-containing PVA containing a structural unit represented by the following formula (1) and having a softening point of 63 ° C. or lower;
• a film capable of easily producing an optical film excellent in optical characteristics and shrinkage reduction, and a method for producing an optical film using the film are provided.
• the film of the present invention contains a vinyl alcohol unit and a hydroxymethyl group-containing PVA containing a structural unit represented by the following formula (1).
• the film of the present invention has improved stretchability because the hydroxymethyl group-containing PVA contained therein contains a structural unit having a 1,3-diol structure represented by the above formula (1). According to this, an optical film having excellent optical properties can be easily produced. Moreover, it has the characteristic that the shrinkage force of an optical film reduces.
• the present invention is not limited in any way, the reason why the above-described advantages can be obtained is that the crystallinity is lowered by the structural unit represented by the formula (1) and the high based on the 1,3-diol structure. The influence of hydrogen bonding force is considered.
• the content of the structural unit represented by the formula (1) in the hydroxymethyl group-containing PVA is not particularly limited, but is 0.1 to 2 when the number of moles of all structural units constituting the hydroxymethyl group-containing PVA is 100 mol%. It is preferably in the range of mol%, more preferably in the range of 0.2 to 1.9 mol%, still more preferably in the range of 0.3 to 1.8 mol%.
• the content is 0.1 mol% or more, the stretchability of the film is further improved, and an optical film that is excellent by reducing the shrinkage force can be obtained.
• the content is 2 mol% or less, dissolution of the film during the production of the optical film can be more effectively prevented, and an optical film excellent in optical properties can be obtained.
• the structural unit refers to a repeating unit constituting a polymer.
• the degree of polymerization of the hydroxymethyl group-containing PVA is preferably in the range of 1,500 to 6,000, more preferably in the range of 1,800 to 5,000, and 2,000 to 4,000. More preferably, it is in the range.
• the degree of polymerization is 1,500 or more, the durability of an optical film such as a polarizing film obtained by uniaxially stretching the film can be further improved.
• the degree of polymerization is 6,000 or less, it is possible to suppress an increase in manufacturing cost, poor process passability during film formation, and the like.
• 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 saponification degree of the hydroxymethyl group-containing PVA is preferably 95 mol% or more, more preferably 96 mol% or more from the viewpoint of water resistance of an optical film such as a polarizing film obtained by uniaxially stretching the film. Preferably, it is 98 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. 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.
• 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) are converted to vinyl alcohol units, while structural units derived from unsaturated monomers that can be converted to structural units represented by formula (1) are converted to structural units represented by formula (1).
• a method 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 represents an alkyl group having 1 to 10 carbon atoms.
• the structure of R is not particularly limited, and may partially have a branched or cyclic structure. Moreover, a part may be substituted with other functional groups.
• R 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, a tert-butyl group, Examples thereof include a linear or branched alkyl group such as a pentyl group. Examples of the substituent that R may have include an alkoxy group, a halogen atom, and a hydroxyl group. A plurality of R may be the same or different from each other.
• Examples of the unsaturated monomer represented by the formula (2) include 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyryloxy-2. -Methylenepropane and the like. Of these, 1,3-diacetoxy-2-methylenepropane is preferably used from the viewpoint of ease of production.
• the unsaturated monomer represented by the formula (2) is a vinyl ester monomer compared with other allylic unsaturated monomers (for example, allyl glycidyl ether) generally used for modification of PVA.
• the copolymerization reaction proceeds easily. Therefore, there are few restrictions on the amount of modification and the degree of polymerization during polymerization, and a hydroxymethyl group-containing PVA having a high degree of modification and a high degree of polymerization can be easily obtained.
• the hydroxymethyl group-containing PVA in the present invention is excellent in terms of environment and cost during industrial production. Yes.
• 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 is allowed to proceed 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 polymerization temperature is not particularly limited, but is suitably about room temperature to 150 ° C., preferably 40 ° C
• 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 into a structural unit having a 1,3-diol structure 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, and may be 99 mol% or more.
• 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
• an unsaturated dicarboxylic acid and a salt or ester thereof; vinylsilyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate since the stretchability is improved and the film can be stretched at a higher temperature, the occurrence of troubles such as breakage of the stretch during the production of the optical film is reduced, and the productivity of the optical film is further improved. preferable.
• the hydroxymethyl group-containing PVA contains an ethylene unit
• the content of the ethylene unit is 100 in terms of the number of moles of all structural units constituting the hydroxymethyl group-containing PVA from the viewpoints of stretchability and stretchable temperature as described above.
• the mol% is preferably 1 to 4 mol%, particularly preferably 2 to 3 mol%.
• 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 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 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 film of the present invention is preferably in the range of 1 to 20 parts by mass, preferably in the range of 3 to 17 parts by mass with respect to 100 parts by mass of the hydroxymethyl group-containing PVA contained therein. More preferably, the content is in the range of 5 to 15 parts by mass. 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.
• the 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, a flame retardant, and other heat.
• 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, a flame retardant, and other heat.
• Additives such as plastic resins, lubricants, fragrances, defoamers, deodorants, extenders, release agents, mold release agents, reinforcing agents, crosslinking agents, fungicides, preservatives, crystallization rate retarders, It can mix
• the proportion of the total of the hydroxymethyl group-containing PVA and the plasticizer in the film of the present invention is preferably 80% by mass or more, more preferably 90% by mass or more based on the mass of the film, and 95% by mass. % Or more is more preferable.
• the film of the present invention has a softening point of 63 ° C. or lower.
• the softening point is preferably 60 ° C. or lower, more preferably 57 ° C. or lower, and further preferably 55 ° C. or lower.
• the lower the softening point the lower the shrinkage force of the resulting optical film.
• the lower limit of the industrial softening point is about 50 ° C. from the viewpoint of process passability during use, such as when the film is uniaxially stretched.
• a film having a softening point in the above range can be easily produced by appropriately adjusting the modification amount of the hydroxymethyl group-containing PVA, the saponification degree of the hydroxymethyl group-containing PVA, the heat treatment temperature for the film, etc.
• a method of setting the temperature lower is simple and preferable.
• the specific heat treatment temperature is preferably 150 ° C. or lower, more preferably 140 ° C. or lower, further preferably 130 ° C. or lower, particularly preferably 120 ° C. or lower, and preferably a temperature exceeding 90 ° C.
• the softening point can be determined by a known measurement method, and specifically can be measured by the method described later in the examples.
• the degree of swelling of the film of the present invention is preferably in the range of 190 to 500%, more preferably in the range of 200 to 400%, and still more preferably in the range of 230 to 350%. A range of 270 to 320% is particularly preferable.
• the degree of swelling is 190% or more, crystallization can be prevented from proceeding extremely, and the film can be stably stretched to a higher magnification.
• the degree of swelling is 500% or less, dissolution during stretching is suppressed, and stretching is possible even under higher temperature conditions.
• the degree of swelling of the film is a value obtained by dividing the mass when the film is immersed in distilled water at 30 ° C. for 30 minutes by the mass after drying at 105 ° C. for 16 hours. It means percentage, and can be specifically measured by the method described later in Examples.
• the thickness of the film of the present invention is not particularly limited, but is generally 1 to 100 ⁇ m, more preferably 5 to 75 ⁇ m, and particularly preferably about 10 to 60 ⁇ m.
• the thickness is too thin, 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.
• the said thickness is too thick, at the time of the uniaxial stretching process for manufacturing an optical film, it will become easy to generate
• the width of the film of the present invention is not particularly limited, and can be determined according to the use of the optical film to be produced. In recent years, liquid crystal televisions and liquid crystal monitors have been increasing in screen size, so that the film width of 3 m or more is suitable for these applications. On the other hand, if the width of the film is too large, it is difficult to uniformly carry out uniaxial stretching per se when an optical film is produced with an apparatus that has been put into practical use. Therefore, the width of the film is preferably 7 m or less. .
• the production method of the 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.
• the above-described hydroxymethyl group-containing PVA constituting the film And, if necessary, a film-forming stock solution in which one or more of the plasticizers, additives, and surfactants described later are dissolved in a liquid medium, and a hydroxymethyl group-containing PVA, In addition, if necessary, it is produced using a film-forming stock solution containing one or more of plasticizers, additives, surfactants, liquid media, etc., in which the hydroxymethyl group-containing PVA is melted. can do.
• 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 prevent the surfactant from bleeding out on the surface of the film to cause blocking and lowering the handleability.
• Examples of the film forming method for forming a film using the above-described 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. 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 film having a uniform thickness and width and excellent physical properties can be obtained. The formed film can be dried or heat-treated as necessary.
• a T-type slit die, a hopper plate, an I-die, a lip coater die or the like is used to rotate the above film forming stock solution on the most upstream side.
• the ingredients are evaporated to dryness, followed by further drying on the circumference of one or more rotating heated rolls located downstream thereof, or by passing through a hot air drying apparatus for further drying.
• a 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 use of the film of the present invention is not particularly limited.
• an optical film excellent in optical properties, durability, and shrinkage reduction can be easily produced, and thus an optical film is produced.
• 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 subjecting the film of the present invention to a treatment such as uniaxial stretching.
• the method for producing a polarizing film using the film of the present invention is not particularly limited, and any method conventionally employed may be employed.
• dyeing and uniaxial stretching may be performed on the film of the present invention, or uniaxial stretching may be performed on the film of the present invention containing a dye.
• a method of subjecting the film of the present invention to swelling, dyeing, uniaxial stretching, and, if necessary, crosslinking treatment, fixing treatment, drying, heat treatment, etc. 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 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.
• a 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 film in a solution (particularly an aqueous solution) containing iodine-potassium iodide as a dyeing bath, and such a dyeing method is also preferably used 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 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 an auxiliary agent such as potassium iodide.
• 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 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 a film after water absorption.
• the wet stretching method is preferable, 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. Further, the aqueous boric acid solution may contain potassium iodide, and its concentration 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 6.8 times or more, more preferably 6.9 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 longitudinal direction is preferred. 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 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 and urethane adhesives, among which PVA adhesives are suitable.
• 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.
• the softening point of the film was measured using an automatic softening point temperature measuring device manufactured by Elex Chemical. Specifically, the films obtained in the following examples, reference examples or comparative examples were cut so as to be 2.5 cm square, and this was fixed to a metal frame having a circular hole with a diameter of 1 cm. A sphere with a diameter of 0.95 cm and a mass of 3.526 g is placed in the center of the tube, and the temperature when the sphere drops 2.5 cm during the temperature rising process from 30 ° C to 5 ° C / min is measured by a sensor. did.
• Optical properties of polarizing film (dichroic ratio) (1) Measurement of transmittance Ts Two 2 cm samples were taken in the length direction of the polarizing film from the central part of the polarizing film obtained in the following Examples, Reference Examples or Comparative Examples, and the spectrophotometer with integrating sphere Using a meter (“V7100” manufactured by JASCO Corporation), in accordance with JIS Z 8722 (measuring method of object color), the visibility correction in the visible light region of C light source and 2 ° field of view is performed, and one sample The light transmittance when tilted by + 45 ° with respect to the length direction and the light transmittance when tilted by ⁇ 45 ° were measured, and the average value Ts1 (%) was obtained.
• V7100 manufactured by JASCO Corporation
• Ts1 and Ts2 were averaged by the following formula (4) to obtain the transmittance Ts (%) of the polarizing film.
• Ts (Ts1 + Ts2) / 2 (4)
• the transmittance Ts (%) and the degree of polarization V (%) were determined for each of these four polarizing films by the method described above, and the transmittance Ts (%) was plotted on the horizontal axis for each example, reference example, and comparative example.
• the points were plotted on a graph to obtain an approximate curve, and the degree of polarization V 44 (%) when the transmittance Ts (%) was 44% was obtained from the approximate curve.
• a rectangular sample of 12 cm in the length direction of the polarizing film and 1.5 cm in the width direction was collected from the central portion of the polarizing film obtained in the examples, reference examples or comparative examples below the shrinkage force of the polarizing film. Humidity was adjusted for 18 hours under the conditions of 20 ° C. and 20% relative humidity. 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%. Stretching in the length direction at a speed, when the tension reaches 2N, the stretching is stopped and held, and in that state, the temperature is raised to 80 ° C., and the tension is measured after 4 hours. Power.
• Example 1 (1) Hydroxymethyl group-containing PVA100 shown in Table 1 obtained by saponifying a copolymer obtained by copolymerizing vinyl acetate and 1,3-diacetoxy-2-methylenepropane at a polymerization temperature of 40 ° C.
• aqueous solution containing 10 parts by mass of glycerin as a plasticizer and 0.1 parts by mass of sodium polyoxyethylene lauryl ether sulfate as a surfactant and having a hydroxymethyl group-containing PVA content of 10% by mass
• the film was dried on a metal roll at 80 ° C., and the resulting film was heat-treated at a predetermined temperature for 1 minute in a hot air dryer to adjust the softening point to 63 ° C., and the thickness was 30 ⁇ m.
• the film was manufactured.
• 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) (temperature 56 ° C.) containing 4% by mass of boric acid and 6% by mass of potassium iodide, the film was uniaxially stretched in the length direction to the stretch ratio immediately before breaking.
• Example 2 [Examples 2 and 3 and Reference Example 1] Except that the temperature (heat treatment temperature) of the hot air dryer was adjusted to 60 ° C. (Example 2); 55 ° C. (Example 3); 64 ° C. (Reference Example 1) as shown in Table 1. A 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.

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