Classifications

• • 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
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D129/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Coating compositions based on hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Coating compositions based on derivatives of such polymers
  • C09D129/02—Homopolymers or copolymers of unsaturated alcohols
  • C09D129/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• • 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
  • C08F16/00—Homopolymers and 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
  • C08F16/02—Homopolymers and 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
  • C08F16/04—Acyclic compounds
  • C08F16/06—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
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0016—Plasticisers
• • 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
  • G02B5/00—Optical elements other than lenses
  • G02B5/30—Polarising elements
• • 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
  • C08F116/00—Homopolymers 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
  • C08F116/02—Homopolymers 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
  • C08F116/04—Acyclic compounds
  • C08F116/06—Polyvinyl alcohol ; Vinyl alcohol
• • 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
• • 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
  • C08J2429/00—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
  • C08J2429/02—Homopolymers or copolymers of unsaturated alcohols
  • C08J2429/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids

Definitions

• the present invention relates to a polyvinyl alcohol-based resin film, an optical film, a water-soluble film, and a polyvinyl alcohol-based resin composition.
• polyvinyl alcohol-based resins have been applied in many fields due to their excellent properties combined with a wide range of qualities. They have excellent gas barrier properties, mechanical strength, transparency, gloss, water solubility, etc., and are used in a wide range of fields, such as optical film applications, packaging for food and healthcare applications, medical infusion bags, packaging for various pharmaceuticals such as liquid detergents and pesticides, and seed tapes for containing seeds.
• Films using these polyvinyl alcohol-based resins are produced by dissolving the polyvinyl alcohol-based resin in a solvent such as water to prepare a stock solution, forming the stock solution into a film using a casting mold such as a metal roll or belt by a solution casting method (casting method), and drying the film using a metal heating roll, a floating dryer, or the like.
• films using polyvinyl alcohol-based resins are widely used as optical polarizing films and individual packaging films for food, health care, and liquid detergents.
• the film performance required for these applications has increased, and for example, in optical applications, the screens of liquid crystal televisions and the like are becoming increasingly bright and high-definition, so that the film is required to have even greater transparency than conventional products.
• liquid detergent packaging applications there is a growing trend to place importance on package design that adds a sense of luxury through ingenious color schemes and designs for liquid detergents as a means of increasing product value, and there is a demand for polyvinyl alcohol-based films with even greater transparency than conventional products.
• Patent Document 1 discloses a method of improving transparency by using a polyvinyl alcohol-based resin having a high degree of polymerization and a polyvinyl alcohol-based resin having a low degree of polymerization and reducing the difference in the degree of saponification between the two types of polyvinyl alcohol-based resins (see Patent Document 1).
• a method has been disclosed in which the generation of droplets in the resulting polyvinyl alcohol-based film can be suppressed by adding a specific surfactant to the film-forming raw material (aqueous solution of a polyvinyl alcohol-based resin), thereby obtaining a high-quality optical film with low haze (see Patent Document 2).
• the present invention provides a polyvinyl alcohol-based resin film, an optical film, a water-soluble film, and a polyvinyl alcohol-based resin composition that can reduce the internal haze caused by additives even when the amount of additives used is reduced, and can control the unevenness near the film surface and reduce the external haze by improving the peelability, etc.
• a plasticizer B
• An optical film comprising the polyvinyl alcohol-based resin film according to any one of [1] to [7].
• a water-soluble film comprising the polyvinyl alcohol-based resin film according to any one of [1] to [6].
• a polyvinyl alcohol-based resin composition containing a polyvinyl alcohol-based resin (A), the polyvinyl alcohol-based resin (A) containing radioactive carbon C14, and a film obtained by solution casting of the polyvinyl alcohol-based resin composition has a total haze value of 1.9 or less.
• a polyvinyl alcohol-based resin film comprising the polyvinyl alcohol-based resin composition according to [11] or [12].
• the polyvinyl alcohol resin film of the present invention has excellent transparency.
• the amount of surfactants used to improve transparency can be reduced, and when the film is formed, the occurrence of surfactant aggregation, surfactant-derived decomposition products, and film defects caused by these can be suppressed.
• the film since the film has excellent peelability, when the film is formed, unevenness on the film surface is reduced, and light scattering on the surface that causes the film to appear cloudy can be suppressed.
• x and/or y (x and y are optional configurations)" means at least one of x and y, and means three possibilities: x only, y only, and x and y.
• X to Y (X and Y are arbitrary numbers)
• it is expressed as "X or more” (X is any number) or "Y or less” (Y is any number) it also means that "it is preferably greater than X” or "it is preferably less than Y”.
• the upper or lower limit of a numerical range described in stages can be arbitrarily combined with the upper or lower limit of a numerical range of another stage.
• the upper or lower limit of the numerical range can be replaced with a value shown in the examples.
• the term “film” also includes the terms “tape” and "sheet.”
• the term “main component” means a component that has a significant effect on the properties of the target object, and the content of the component in the target object is usually 50 mass % or more, preferably 55 mass % or more, more preferably 60 mass % or more, and even more preferably 70 mass % or more, and may be 100 mass %.
• the polyvinyl alcohol-based resin film (hereinafter, sometimes referred to as "the present polyvinyl alcohol-based resin film") contains a polyvinyl alcohol-based resin containing radioactive carbon C14, and the total haze of the polyvinyl alcohol-based resin film is 1.9 or less.
• the total haze of the polyvinyl alcohol-based resin film must be 1.9 or less, preferably 1.8 or less, particularly preferably 1.7 or less, and further preferably 1.65 or less.
• the lower limit of the total haze is preferably 0 or more, since the lower the better.
• the polyvinyl alcohol resin film needs to contain at least a polyvinyl alcohol resin (A), and preferably contains a plasticizer (B) as another component, and may contain surfactants (C), starch (D), water-soluble polymers other than (A) (E), etc., as necessary.
• the present polyvinyl alcohol-based resin film is required to contain at least one type of "polyvinyl alcohol-based resin (A1) in which all or a part of the carbon constituting the polyvinyl alcohol-based resin is derived from biological ethylene.”
• the polyvinyl alcohol-based resin (A) used may be a "polyvinyl alcohol-based resin (A1) in which all or a part of the carbon constituting the polyvinyl alcohol-based resin is derived from biological ethylene” alone, or a mixture of a "polyvinyl alcohol-based resin (A1) in which all or a part of the carbon constituting the polyvinyl alcohol-based resin is derived from biological ethylene” and a "polyvinyl alcohol-based resin (A'1) obtained only from raw materials derived from fossil fuels" may be used.
• polyvinyl alcohol-based resin (A1) in which all or a part of the carbon constituting the polyvinyl alcohol-based resin is derived from biological ethylene For example, (1) A method of obtaining only polyvinyl ester by polymerizing only biovinyl ester monomers obtained from bioethylene as a raw material, and saponifying the resulting polyvinyl ester alone; (2) A method for obtaining polyvinyl ester by polymerizing a biovinyl ester monomer using a mixture of bioethylene and ethylene derived from fossil fuels as raw materials, and saponifying the resulting polyvinyl ester; (3) A method for obtaining polyvinyl ester by saponifying a polyvinyl ester obtained by copolymerizing a biovinyl ester monomer obtained from bioethylene and a vinyl ester monomer obtained from ethylene derived from a fossil fuel; (4) A method of saponifying a mixture of polyvinyl ester obtained by
• the method (1) or (2) is preferred in that it is possible to efficiently produce a polyvinyl alcohol-based resin (A1) in which all or a part of the carbon constituting the polyvinyl alcohol-based resin is derived from biological ethylene.
• vinyl ester monomers examples include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and vinyl versatate, with vinyl acetate being preferred.
• vinyl ester monomer there are no particular limitations on the method for producing a vinyl ester monomer, and it can be obtained, for example, by reacting ethylene with a compound having a carboxy group represented by R-COOH.
• Vinyl acetate can be synthesized as follows. Usually, vinyl acetate can be obtained by a gas-phase reaction of ethylene, acetic acid, and oxygen in the presence of a catalyst. At this time, vinyl acetate containing a predetermined amount of C14 can be obtained by using ethylene containing a predetermined amount of C14 or acetic acid containing a predetermined amount of C14 as the compound having a carboxy group.
• An example of ethylene containing a predetermined amount of C14 is bioethylene.
• the polyvinyl ester is preferably one obtained by using one or more vinyl ester monomers, and more preferably one obtained by using only one vinyl ester monomer.
• the polyvinyl ester may also be a copolymer of one or more vinyl ester monomers with other monomers copolymerizable therewith.
• Ethylene is preferred as another monomer copolymerizable with the vinyl ester monomer. That is, the polyvinyl alcohol contained in the polyvinyl alcohol-based resin film of the present invention preferably contains an ethylene unit.
• the content of the ethylene unit is preferably 1 mol% or more, more preferably 1.5 mol% or more, based on the number of moles of all structural units constituting the vinyl ester polymer.
• the content of the ethylene unit is preferably less than 15 mol%, more preferably less than 10 mol%, based on the number of moles of all structural units constituting the vinyl ester polymer.
• the content of the ethylene unit is in the above range, when the polyvinyl alcohol-based resin film of the present invention is used as a raw film for manufacturing an optical film, the water resistance, etc. of the polyvinyl alcohol-based resin film can be improved without significantly impairing the optical properties of the polyvinyl alcohol-based resin film.
• the reason for this is not necessarily clear, but it is presumed that while the hydrophilicity is weakened by introducing the ethylene unit into the polymer main chain, the volume occupied by the ethylene unit in the crystal is not significantly different from the volume of the vinyl alcohol unit, so that the crystal structure of the polyvinyl alcohol is not significantly disturbed.
• vinyl ester monomers include, in addition to ethylene, olefins having 3 to 30 carbon atoms such as propylene, 1-butene, and isobutene; acrylic acid or its salts; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid or its salts; methyl methacrylate, ethyl methacrylate, Methacrylic acid esters such as n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-but
• the proportion of structural units derived from other monomers in the polyvinyl ester is preferably 15 mol % or less, and more preferably 5 mol % or less, based on the number of moles of all structural units constituting the polyvinyl ester, from the viewpoints of the strength of the resulting polyvinyl alcohol resin film and the optical performance when the polyvinyl alcohol resin film is used as a raw film for manufacturing optical films.
• Other monomers copolymerizable with vinyl ester monomers may be monomers derived from fossil fuels or monomers derived from plants.
• the weight average molecular weight of the polyvinyl alcohol resin (A) is preferably 20,000 to 150,000, particularly preferably 60,000 to 130,000, and even more preferably 70,000 to 120,000. If the weight average molecular weight is too small, the mechanical strength tends to decrease, while if it is too large, the productivity tends to decrease. Furthermore, if the weight average molecular weight is too small, it tends to be difficult to obtain sufficient optical performance when the polyvinyl alcohol resin is used as an optical film, while if it is too large, it tends to be difficult to stretch the polyvinyl alcohol resin film when a polarizing film is manufactured using the polyvinyl alcohol resin film.
• the weight average molecular weight of the polyvinyl alcohol resin is a weight average molecular weight measured by GPC.
• the polydispersity (weight average molecular weight/number average molecular weight) of the polyvinyl alcohol resin (A) is preferably from 1.95 to 3.50, particularly preferably from 1.96 to 2.50, and further preferably from 1.97 to 2.10. If the dispersity is too small, stretching tends to be difficult when a polarizing film is produced using the polyvinyl alcohol-based resin film, whereas if the dispersity is too large, sufficient optical performance tends to be difficult to obtain when the polyvinyl alcohol-based resin is used as an optical film.
• the weight average molecular weight and number average molecular weight when measuring the dispersity of the polyvinyl alcohol resin are those measured by a GPC method.
• the average saponification degree of the polyvinyl alcohol-based resin (A) is preferably 80 mol% or more, more preferably 87 mol% or more, particularly preferably 99 mol% or more, further preferably 99.5 mol% or more, and particularly preferably 99.8 mol% or more. If the average saponification degree is too low, sufficient optical properties tend not to be obtained when the polyvinyl alcohol-based resin film is used as a polarizing film.
• the average degree of saponification in this specification is measured in accordance with JIS K6726.
• the polyvinyl alcohol resin (A) contains radioactive carbon C14.
• the term "containing radioactive carbon C14” means that the biomass content measured by ASTM D6866 (Method B) specified by the American Society of Testing and Materials is greater than 0%.
• the biomass degree calculated from the measured value of radiocarbon C14 is preferably 5% or more, more preferably 45% or more, even more preferably 50% or more, and particularly preferably 55% or more. It is also preferably less than 100%, more preferably 95% or less, even more preferably 90% or less, and particularly preferably 83% or less.
• the polyvinyl alcohol resin used as the base resin has excellent transparency, and furthermore, it is possible to reduce the amount of surfactant used that affects the decrease in transparency, and when forming a film, it is possible to suppress the occurrence of surfactant aggregation, surfactant-derived decomposition products, and film defects caused by them, etc. Furthermore, since it has excellent peelability, when forming a film, the unevenness of the film surface is mitigated, and it is also possible to suppress the film from appearing cloudy due to light scattering on the surface.
• polyvinyl alcohol-based resin (A) one type of polyvinyl alcohol may be used, or two or more types of polyvinyl alcohols having different degrees of polymerization, saponification, or modification may be blended.
• plasticizer (B) examples include glycerols such as glycerin, diglycerin, and triglycerin, alkylene glycols such as triethylene glycol, polyethylene glycol, polypropylene glycol, dipropylene glycol, and propylene glycol, and sugar alcohols such as trimethylolpropane, sorbitol, xylitol, and maltitol. These can be used alone or in combination of two or more. Among them, glycerin, polyethylene glycol, and diglycerin are preferably used because they are easily available and can obtain a plasticizing effect in a small amount.
• glycerols such as glycerin, diglycerin, and triglycerin
• alkylene glycols such as triethylene glycol, polyethylene glycol, polypropylene glycol, dipropylene glycol, and propylene glycol
• sugar alcohols such as trimethylolpropane
• the content of the plasticizer (B) is preferably 1 to 45 parts by mass, more preferably 3 to 30 parts by mass, and even more preferably 5 to 25 parts by mass, per 100 parts by mass of the polyvinyl alcohol-based resin (A). If the content of the plasticizer (B) is too low, the stretchability during the preparation of the polarizing film tends to decrease, and if the content is too high, the strength of the resulting polyvinyl alcohol-based resin film tends to decrease.
• the surfactant (C) generally serves to smooth the film surface and to inhibit adhesion of the films to each other when wound into a roll.
• nonionic surfactants, anionic surfactants, and cationic surfactants can be used alone or in combination of two or more thereof.
• nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene hexyl ether, polyoxyethylene heptyl ether, polyoxyethylene octyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene dodecyl ether, polyoxyethylene tetradecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene octadecyl ether, polyoxyethylene eicosyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, coconut oil reduced alcohol ethylene oxide adduct, and beef tallow reduced alcohol ethylene oxide adduct; caproic acid mono- or diethanolamide, caprylic acid mono- or diethanolamide, capric acid mono- or diethanolamide, lauric acid mono- or diethanolamide, palmitic acid mono- or diethanolamide, stearic acid mono- or diethanolamide, oleic acid
• higher fatty acid amides such as capric acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, and oleic acid amide, hydroxyethyl laurylamine, polyoxyethylene hexylamine, polyoxyethylene heptylamine, polyoxyethylene octylamine, polyoxyethylene nonylamine, polyoxyethylene decylamine, polyoxyethylene dodecylamine, polyoxyethylene tetradecylamine, polyoxyethylene hexadecylamine, polyoxyethylene octadecylamine, polyoxyethylene oleylamine, polyoxyethylene laurylamine, polyoxyethylene Examples of such amines include polyoxyethylene alkylamines such as oxyethylene eicosylamine, polyoxyethylene caproic acid amide, polyoxyethylene caprylic acid amide, polyoxyethylene capric acid amide, polyoxyethylene lauric acid amide, polyoxyethylene palmitic acid amide, polyoxyethylene
• anionic surfactants include, for example, alkyl sulfate ester salts such as sulfate ester salts, sodium hexyl sulfate, sodium heptyl sulfate, sodium octyl sulfate, sodium nonyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium hexadecyl sulfate, sodium octadecyl sulfate, sodium eicosyl sulfate, or potassium salts, calcium salts, ammonium salts, etc.; polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene hexyl ether sulfate, sodium polyoxyethylene heptyl ether sulfate, sodium polyoxyethylene octyl ether sulfate, sodium poly
• examples of the sulfate salt type include fatty acid soaps, N-acylamino acids and their salts, polyoxyethylene alkyl ester carboxylates, acylated peptides, and other carboxylate salt types; alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, formalin polycondensates of naphthalene sulfonic acid salts, formalin condensates of melamine sulfonic acid salts, dialkyl sulfosuccinate ester salts, alkyl sulfosuccinate disalts, polyoxyethylene alkyl sulfosuccinate disalts, alkyl sulfoacetates, ⁇ -olefin sulfonates, N-acyl methyl taurine salts, and dimethyl-5-sulfoisophthalate sodium
• Examples of the cationic surfactant include laurylamine hydrochloride, lauryltrimethylammonium chloride, laurylpyridinium chloride, etc.
• nonionic surfactants are preferred, and higher fatty acid alkanolamides are particularly preferred, with lauric acid mono- or diethanolamide, palmitic acid mono- or diethanolamide, stearic acid mono- or diethanolamide, and oleic acid mono- or diethanolamide being even more preferred, with lauric acid mono- or diethanolamide being even more preferred, and lauric acid diethanolamide being even more preferred.
• the surfactant (C) may be used alone or in combination of two or more kinds, and it is preferable to use an anionic surfactant and a nonionic surfactant in combination in terms of film transparency.
• the content of the surfactant (C) is preferably 0.01 to 1 part by mass, particularly preferably 0.02 to 0.5 parts by mass, and even more preferably 0.03 to 0.2 parts by mass, per 100 parts by mass of the polyvinyl alcohol-based resin (A). If the content of the surfactant (C) is too low, it tends to be difficult to achieve the blocking prevention effect, and if it is too high, the transparency of the film tends to decrease.
• the amount of the anionic surfactant is preferably 0.01 to 1 part by mass, particularly 0.02 to 0.2 parts by mass, and more preferably 0.03 to 0.1 parts by mass
• the amount of the nonionic surfactant is preferably 0.01 to 1 part by mass, particularly 0.02 to 0.2 parts by mass, and more preferably 0.03 to 0.1 parts by mass, per 100 parts by mass of the polyvinyl alcohol resin (A).
• the amount of the anionic surfactant is too small, the dispersibility of the dye during the preparation of the polarizing film tends to decrease, and dyeing spots tend to increase, while if the amount is too large, foaming occurs violently when the polyvinyl alcohol resin is dissolved, and air bubbles tend to be mixed into the film, making it impossible to use the film for optical purposes. If the amount of the nonionic surfactant is too small, it is difficult to obtain an anti-blocking effect, and if the amount is too large, the transparency and flatness of the film tend to decrease.
• starch (D) examples include raw starch (corn starch, potato starch, sweet potato starch, wheat starch, cassava starch, sago starch, tapioca starch, sorghum starch, rice starch, bean starch, kudzu starch, bracken starch, lotus starch, water chestnut starch, etc.), physically modified starch ( ⁇ -starch, fractionated amylose, moist heat treated starch, etc.), enzyme modified starch (hydrolyzed dextrin, enzymatically decomposed dextrin, amylose, etc.), chemically decomposed modified starch (acid treated starch, hypochlorite oxidized starch, dialdehyde starch, etc.), chemically modified starch derivatives (esterified starch, etherified starch, cationized starch, crosslinked starch, etc.), etc.
• raw starch particularly corn starch and rice starch, are preferably used
• the content of such starch (D) is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of polyvinyl alcohol-based resin (A). If the amount of starch (D) is more than 15 parts by mass, there is a risk of the process passability being deteriorated during the production of the polyvinyl alcohol-based resin film.
• examples of the water-soluble polymer (E) other than the polyvinyl alcohol-based resin (A) include dextrin, gelatin, glue, casein, shellac, gum arabic, polyacrylic acid amide, sodium polyacrylate, polyvinyl methyl ether, a copolymer of methyl vinyl ether and maleic anhydride, a copolymer of vinyl acetate and itaconic acid, polyvinylpyrrolidone, cellulose, acetyl cellulose, acetyl butyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, sodium alginate, etc. These may be used alone or in combination of two or more kinds.
• the content of the water-soluble polymer (E) is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the polyvinyl alcohol-based resin (A). If the content of the water-soluble polymer (E) is more than 15 parts by mass, the physical properties of the polyvinyl alcohol-based resin film may be impaired.
• the polyvinyl alcohol-based resin film may contain components such as water, antioxidants, ultraviolet absorbers, lubricants, crosslinking agents, colorants, fillers, preservatives, antifungal agents, other polymer compounds, etc., in addition to plasticizers, surfactants, starch, and water-soluble polymers other than the polyvinyl alcohol-based resin (A), as long as the effects of the present invention are not impaired. These may be used alone or in combination of two or more kinds.
• the polyvinyl alcohol-based resin film is preferably a film obtained using a polyvinyl alcohol-based resin composition.
• the method for producing the polyvinyl alcohol-based resin film includes using a film-forming stock solution (aqueous solution of a polyvinyl alcohol-based resin composition) obtained by adding a solvent, additives, etc.
• the polyvinyl alcohol-based resin (A) to homogenize it, and forming the film by any method, such as a casting film-forming method, a wet film-forming method (discharging into a poor solvent), a dry-wet film-forming method, a gel film-forming method (a method in which the film-forming stock solution is cooled and gelled, and then the solvent is extracted and removed to obtain a polyvinyl alcohol-based resin film), or a combination of these methods, or a melt extrusion film-forming method or inflation molding method in which the film-forming stock solution is obtained using an extruder or the like and extruded from a T-die or the like to form a film.
• a casting film-forming method such as a casting film-forming method, a wet film-forming method (discharging into a poor solvent), a dry-wet film-forming method, a gel film-forming method (a method in which the film-forming stock solution is cooled and gelled, and then the solvent is extracted and
• the casting film-forming method and the melt extrusion film-forming method are preferred because they can produce a homogeneous film with good productivity.
• the casting film-forming method and the melt extrusion film-forming method of the polyvinyl alcohol-based resin film will be described.
• the film production solution is degassed, cast in the form of a film onto a support such as a metal roll or a metal belt, and heated to remove the solvent, thereby solidifying and forming a film.
• degassing methods include static degassing and degassing using a multi-screw extruder with a vent.
• a multi-screw extruder with a vent a twin-screw extruder with a vent is usually used.
• the solidified film is peeled off from the support, dried using a drying roll or drying oven, etc. as necessary, and further heat-treated as necessary, and wound up to obtain a long roll of polyvinyl alcohol-based resin film.
• the resin concentration of the film-forming solution (the concentration of non-volatile components such as polyvinyl alcohol resins that are not removed by volatilization or evaporation during film formation, etc.) is preferably 10 to 60% by mass, particularly preferably 12 to 55% by mass, and even more preferably 20 to 50% by mass. If the resin concentration of such an aqueous solution is too low, the drying load will be large and production capacity will tend to decrease, and if it is too high, the viscosity will be too high and it will tend to be difficult to dissolve uniformly.
• the "resin concentration of the film-forming solution” refers to the volatile content calculated using the following formula.
• the method for preparing the film-forming solution includes dissolving polyvinyl alcohol resin (A) and additives such as plasticizer (B) and surfactant (C) in a dissolution tank, or melt-kneading hydrous polyvinyl alcohol together with plasticizer (B), surfactant (C), etc., using a single-screw extruder or twin-screw extruder.
• additives such as plasticizer (B) and surfactant (C) in a dissolution tank, or melt-kneading hydrous polyvinyl alcohol together with plasticizer (B), surfactant (C), etc.
• the film-producing solution is cast in the form of a film onto a support such as a metal roll or metal belt from a film-producing device, and is heated to remove the solvent, solidifying it into a film.
• the surface temperature of the support onto which the film-forming solution is cast is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher.
• the surface temperature of the support onto which the film-forming solution is cast is preferably 110°C or lower, more preferably 100°C or lower, and even more preferably 95°C or lower. If the surface temperature is too low, the film obtained by film-forming tends to have poor releasability when peeled from the cast mold, and if the surface temperature is too high, foaming tends to occur.
• the drying speed may be adjusted by uniformly blowing hot air at a speed of 1 to 10 m/sec onto the entire area of the non-contact side of the polyvinyl alcohol film while heating the polyvinyl alcohol resin film on the support.
• the temperature of the hot air blown onto the non-contact side is preferably 50°C or higher, and more preferably 70°C or higher.
• the temperature of the hot air blown onto the non-contact side is preferably 150°C or lower, and more preferably 120°C or lower.
• the polyvinyl alcohol-based resin film peeled off from the support is dried on the support preferably until the volatile content is 5 to 50% by mass, and then peeled off, and further dried as necessary.
• the drying method includes contacting with a drying oven or a drying roll.
• a drying oven or a drying roll When drying is performed using a plurality of drying rolls, it is preferable to alternately contact one side and the other side of the film with the drying rolls in order to make both sides uniform.
• the number of drying rolls is preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more.
• the number of drying rolls is preferably 30 or less.
• the time for which each drying roll contacts the film is preferably 1 to 60 seconds, particularly preferably 2 to 30 seconds, more preferably 3 to 20 seconds, and especially preferably 4 to 10 seconds. If the contact time is too short, the film tends to be insufficiently dried, and if the contact time is too long, the load on the equipment tends to increase.
• the temperatures of all drying ovens and drying rolls used are preferably 40 to 150°C, particularly preferably 50 to 140°C, further preferably 60 to 130°C, and particularly preferably 70 to 120°C. If the temperature of the drying oven or drying roll is too low, the drying tends to be insufficient, whereas if it is too high, crystallization of the polyvinyl alcohol resin proceeds, tending to make the film too hard.
• the dried polyvinyl alcohol resin film may be further heat-treated as necessary for the purpose of adjusting physical properties such as strength and water solubility.
• the heat treatment in the present invention is preferably performed from both sides of the film, since it can make both sides of the film uniformly dry. Examples of such heat treatment methods include a method of blowing hot air onto both sides of the film using a floating dryer, and a method of irradiating both sides of the film with near-infrared rays using an infrared lamp.
• the heat treatment temperature is preferably 50 to 150° C., and particularly preferably 70 to 120° C.
• the heat treatment time is not particularly limited, but when a floating dryer is used, it is preferably 10 to 100 seconds, and particularly preferably 20 to 80 seconds.
• the polyvinyl alcohol resin film produced in this manner is further subjected to humidity conditioning treatment and cutting of both ends (edges) of the film as necessary, then wound into a roll on a cylindrical core and packaged in a moisture-proof package to complete the product.
• the volatile content of the polyvinyl alcohol-based resin film finally obtained by the above-mentioned series of processes is not necessarily limited.
• the volatile content of the polyvinyl alcohol-based resin film is preferably 1% by mass or more, and more preferably 2% by mass or more.
• the volatile content of the polyvinyl alcohol-based resin film is preferably 10% by mass or less, and more preferably 5% by mass or less.
• the length of the polyvinyl alcohol resin film thus obtained is preferably 0.5 km or more from the viewpoint of production efficiency, more preferably 1 km or more, and particularly preferably 5 to 50 km from the viewpoint of transportation weight. If the length is too short, switching the film tends to be troublesome, and if it is too long, there is a tendency for the film to become too heavy or have a poor appearance due to tight winding.
• the width of the polyvinyl alcohol resin film is appropriately selected depending on the application, etc., but is preferably 300 to 8,000 mm, particularly preferably 500 to 7,000 mm, and even more preferably 600 to 6,000 mm. If the width is too narrow, production efficiency tends to decrease, and if it is too wide, sagging and control of film thickness tend to become difficult.
• the thickness of the polyvinyl alcohol resin film is selected appropriately depending on the application, etc., but is preferably 10 to 130 ⁇ m, particularly preferably 15 to 110 ⁇ m, and even more preferably 15 to 60 ⁇ m. If the thickness is too thin, the mechanical strength of the film tends to decrease, and if it is too thick, the film production efficiency tends to decrease.
• the polyvinyl alcohol-based resin film has a peel strength of preferably 4.49 N/m or less, more preferably 4.45 N/m or less, even more preferably 4.38 N/m or less, and particularly preferably 4.30 N/m or less, when the film is subjected to the following peel test under an atmosphere of 23° C. and 40% RH.
• the lower limit of the peel strength is not particularly specified, but a value closer to zero is preferable, and from the viewpoint of transport stability, a value of 0.10 N/m or more is more preferable, and a value of 0.15 N/m or more is even more preferable.
• the stainless steel plate coated with the polyvinyl alcohol-based resin composition is then placed on the fixed table of an autograph (manufactured by Shimadzu Corporation, AG-IS), and the strength (N) when peeled 180 degrees from the coated end face in the length direction at a speed of 300 mm/min is measured using a precision universal testing machine (manufactured by Shimadzu Corporation, AG-IS).
• the average value of the strength in the 100 mm section in the center of the length direction, excluding the section 50 mm from the start of peeling and the section 50 mm before the end of peeling is converted to the strength per 1 m of width and is taken as the peel strength (N/m).
• the difference between the breaking strength and the yield strength is preferably 4 N/mm2 or more , more preferably 5 N/mm2 or more, even more preferably 6 N/ mm2 or more, and particularly preferably 7 N/mm2 or more .
• the polyvinyl alcohol-based resin film is conditioned at 23°C and 50% RH for 24 hours or more, and cut into a strip of 15 mm wide x 120 mm long with the coating direction as the longitudinal direction to obtain a test piece.
• a tensile test is performed using a precision universal testing machine (Shimadzu Corporation, AG-IS) in accordance with JIS K 7127 under conditions of a chuck distance of 50 mm and a tensile test speed of 1000 mm/min, and the yield strength (N/ mm2 ) and breaking strength (N/ mm2 ) are measured with the film thickness at the center of the test piece being the thickness of the test piece.
• the above tensile test is performed three times, and the average values are taken as the yield strength and breaking strength of the polyvinyl alcohol-based resin film, and the difference between the yield strength and breaking strength of the polyvinyl alcohol-based resin film is calculated.
• the polyvinyl alcohol-based resin used in the polyvinyl alcohol-based resin film has a biomass degree calculated from the measured value of radiocarbon C14 of preferably 3% or more, more preferably 5% or more, even more preferably 8% or more, and particularly preferably 9% or more. Also, it is preferably less than 50%, more preferably 45% or less, even more preferably 40% or less, and particularly preferably 35% or less.
• the polyvinyl alcohol-based resin used as a base resin has excellent transparency, and further, breakage of the polyvinyl alcohol-based resin film can be further suppressed in applications where stretching processing is performed, such as in the production of polarizing films.
• the polyvinyl alcohol resin film thus obtained is characterized by its high transparency and excellent antistatic properties, and is therefore useful for polarizing film applications requiring high optical properties (such as liquid crystal televisions, smartphones, tablets, personal computers, projectors, and in-vehicle panels) and water-soluble film applications (unit packaging applications for pharmaceuticals such as pesticides and detergents, (hydraulic) transfer films, sanitary products such as napkins and disposable diapers, waste disposal products such as ostomy bags, medical products such as blood-absorbing sheets, and temporary substrates such as seedling sheets, seed tapes, and embroidery base fabrics).
• polarizing film applications requiring high optical properties such as liquid crystal televisions, smartphones, tablets, personal computers, projectors, and in-vehicle panels
• water-soluble film applications unit packaging applications for pharmaceuticals such as pesticides and detergents, (hydraulic) transfer films, sanitary products such as napkins and disposable diapers, waste disposal products such as ostomy bags, medical products such as blood-absorbing sheets, and temporary substrates such as seed
• the polarizing film a method for producing a polarizing film according to one embodiment of the present invention (hereinafter, sometimes referred to as “the polarizing film”).
• This polarizing film is produced by unrolling the polyvinyl alcohol resin film from a roll and transporting it horizontally, then going through processes such as swelling, dyeing, crosslinking, stretching, washing, and drying.
• the swelling process is carried out before the dyeing process.
• the swelling process not only cleans dirt from the surface of the polyvinyl alcohol resin film, but also prevents uneven dyeing by swelling the polyvinyl alcohol resin film.
• water is usually used as the treatment liquid. If the treatment liquid is mainly composed of water, it may contain small amounts of additives such as iodide compounds and surfactants, alcohol, etc.
• the temperature of the swelling bath is usually around 10 to 45°C, and the immersion time in the swelling bath is usually around 0.1 to 10 minutes.
• the dyeing process is carried out by contacting the film with a liquid containing iodine or a dichroic dye.
• a liquid containing iodine or a dichroic dye usually, an aqueous solution of iodine-potassium iodide is used, with the iodine concentration usually being 0.1-2 g/L and the potassium iodide concentration usually being 1-100 g/L.
• a practical dyeing time is usually about 30-500 seconds.
• the temperature of the treatment bath is preferably 5-50°C.
• the aqueous solution may contain a small amount of an organic solvent that is compatible with water in addition to the water solvent.
• the crosslinking step is carried out using a boron compound such as boric acid or borax.
• the boron compound is used in the form of an aqueous solution or an aqueous-organic solvent mixture at a concentration of usually about 10 to 100 g/L, and it is preferable to have potassium iodide coexist in the solution from the viewpoint of stabilizing the polarizing performance.
• the treatment temperature is usually about 30 to 70° C., and the treatment time is preferably about 0.1 to 20 minutes. If necessary, a stretching operation may be carried out during the treatment.
• the stretching process is preferably performed 3 to 10 times in one axial direction, and particularly preferably 3.5 to 6 times. At this time, slight stretching (stretching to the extent that shrinkage in the width direction is prevented, or even more) may also be performed in the direction perpendicular to the stretching direction.
• the temperature during stretching is preferably 30 to 170°C.
• the final stretching ratio need only be set within the above range, and the stretching operation may be performed not only in one stage, but in any range of stages in the manufacturing process.
• the cleaning process is carried out, for example, by immersing the polyvinyl alcohol resin film in water or an aqueous solution of an iodide such as potassium iodide, and can remove precipitates that form on the surface of the film.
• an aqueous solution of potassium iodide such as potassium iodide
• the potassium iodide concentration may be about 1 to 80 g/L.
• the temperature during the cleaning process is usually 5 to 50°C, preferably 10 to 45°C.
• the processing time is usually 1 to 300 seconds, preferably 10 to 240 seconds. Note that water cleaning and cleaning with an aqueous solution of potassium iodide may be combined as appropriate.
• the drying process can be carried out in normal air at 40 to 80°C for 1 to 10 minutes.
• the polarization degree of the polarizing film is preferably 99.8% or more, and particularly preferably 99.9% or more. If the polarization degree is too low, it tends to be difficult to ensure contrast in a liquid crystal display.
• the degree of polarization is calculated according to the following formula using the light transmittance (H11) measured at a wavelength ⁇ when two polarizing films are stacked together so that their orientation directions are in the same direction, and the light transmittance (H1) measured at a wavelength ⁇ when two polarizing films are stacked together so that their orientation directions are perpendicular to each other. [(H11-H1)/(H11+H1)] 1/2
• the single transmittance of the polarizing film is preferably 42% or more, and particularly preferably 43% or more. If the single transmittance is too low, it tends not to be possible to achieve high brightness in liquid crystal displays.
• the single transmittance is a value obtained by measuring the light transmittance of the polarizing film alone using a spectrophotometer.
• the polarizing film is obtained, which is suitable for producing polarizing plates with minimal unevenness in the degree of polarization.
• the obtained polarizing film can also be used as a polarizing plate by laminating and adhering an optically isotropic polymer film or sheet as a protective film on one or both sides thereof.
• the protective film include films or sheets of cellulose triacetate, cellulose diacetate, polycarbonate, polymethyl methacrylate, crosslinked methacrylate resins, cycloolefin polymers, cycloolefin copolymers, polystyrene, polyethersulfone, polyarylene ester, poly-4-methylpentene, polyphenylene oxide, etc.
• a curable resin such as a urethane resin, an acrylic resin, or a urea resin may be applied to one or both sides of the polarizing film, instead of the protective film, and then cured and laminated.
• the polarizing film obtained from this polyvinyl alcohol-based resin film has no color unevenness and has excellent in-plane uniformity of polarization performance, and is preferably used in, for example, liquid crystal display devices such as portable information terminals, personal computers, televisions, projectors, signage, electronic desk calculators, electronic clocks, word processors, electronic paper, game consoles, videos, cameras, photo albums, thermometers, audio equipment, instruments for automobiles and machinery, sunglasses, anti-glare glasses, 3D glasses, wearable displays, anti-reflection layers for display elements (CRT, LCD, organic EL, electronic paper, etc.), optical communication devices, medical devices, building materials, toys, etc.
• liquid crystal display devices such as portable information terminals, personal computers, televisions, projectors, signage, electronic desk calculators, electronic clocks, word processors, electronic paper, game consoles, videos, cameras, photo albums, thermometers, audio equipment, instruments for automobiles and machinery, sunglasses, anti-glare glasses, 3D glasses, wearable displays, anti-reflection layers
• GPC gel permeation chromatography
• Detector RI, Shodex RI-501 Column: TSKgel ⁇ -M 13 ⁇ m 7.8 mm ID ⁇ 30 cm manufactured by Tosoh Corporation was used.
• ⁇ Peel strength> The obtained aqueous solution of the polyvinyl alcohol-based resin composition was applied to a chrome-plated stainless steel plate placed on a hot plate heated to 90° C. using an applicator (width 150 mm) to a length of 200 mm so that the film thickness after drying was 45 ⁇ m, and the plate was left to stand on the hot plate at 90° C. for 2.5 minutes, and the coated end was cut off horizontally in the width direction by 10 mm to be trimmed.
• an applicator width 150 mm
• the stainless steel plate coated with the polyvinyl alcohol-based resin composition was placed on the fixed table of an autograph (manufactured by Shimadzu Corporation, AG-IS), and the strength (N) when peeled 180 degrees from the coated end face in the length direction at a speed of 300 mm/min was measured using a precision universal testing machine (manufactured by Shimadzu Corporation, AG-IS).
• the average value of the strength in the central 100 mm section in the length direction, excluding the section 50 mm from the start of peeling and the section 50 mm before the end of peeling was converted to the strength per 1 m of width and used as the peel strength (N/m). All of these operations were carried out in an atmosphere of 23° C. and 40% RH.
• the peel strength (N/m) was measured five times, and the average value is shown in Table 1 as the peel strength of the polyvinyl alcohol-based resin film.
• ⁇ Tensile test> The obtained polyvinyl alcohol-based resin film was conditioned at 23°C and 50% RH for 24 hours or more, and cut into a strip shape with a width of 15 mm and a length of 120 mm with the coating direction as the longitudinal direction to obtain a test piece.
• a tensile test was carried out using a precision universal testing machine (Shimadzu Corporation, AG-IS) in accordance with JIS K 7127 under conditions of a chuck distance of 50 mm and a tensile test speed of 1000 mm/min, and the yield strength (N/ mm2 ) and breaking strength (N/ mm2 ) were obtained with the film thickness at the center of the test piece being the thickness of the test piece.
• the thus obtained methanol solution of polyvinyl acetate was diluted with methanol to a concentration of 4% by mass, and 2500 parts by mass of this polyvinyl acetate methanol solution (100 parts by mass as polyvinyl acetate) was charged into the same reactor as above.
• the reactor was immersed in a water bath and heated to an internal temperature of 65°C. 26.7 parts by mass of a 3.5% by mass solution of sodium hydroxide in methanol was added thereto to start the saponification reaction. As the saponification reaction proceeds, a saponified product precipitates, but stirring was continued as it is.
• the washed saponified product was dried in a vacuum dryer at 50° C. for 12 hours to obtain a polyvinyl alcohol resin (A1) (bio-derived PVA resin) (weight average molecular weight 81000; biomass degree 95%; saponification degree 99.8 mol%).
• A1 bio-derived PVA resin
• the thus obtained methanol solution of polyvinyl acetate was diluted with methanol to a concentration of 6% by mass, and 2000 parts by mass of this polyvinyl acetate methanol solution (120 parts by mass as polyvinyl acetate) was charged into the same reactor as above.
• the reactor was immersed in a water bath and heated to an internal temperature of 50°C. 128 parts by mass of a 3.5% by mass solution of sodium hydroxide in methanol was added thereto to start the saponification reaction. As the saponification reaction proceeds, a saponified product precipitates, but stirring was continued as it is.
• A′1 polyvinyl
• Example 1 The polyvinyl alcohol-based resin (A1) (bio-derived PVA resin) and polyvinyl alcohol-based resin (A'1) (petroleum-derived PVA resin) obtained in the above Synthesis Example were mixed in a mass ratio of 60:40 to obtain 100 parts by mass of polyvinyl alcohol-based resin (A), and 12 parts by mass of glycerin (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., special grade reagent) was added as a plasticizer (B). Ion-exchanged water was added to the composition so that the concentration of the composition became 19% by mass, and the mixture was dissolved at 130°C for 1 hour using an autoclave to obtain an aqueous polyvinyl alcohol-based resin composition.
• A1 bio-derived PVA resin
• the aqueous solution of the polyvinyl alcohol-based resin composition was applied to a chrome-plated stainless steel plate placed on a hot plate heated to 90° C. using an applicator (coating width 150 mm) so that the film thickness after drying would be 45 ⁇ m, and the film was dried on the hot plate at 90° C. for 2.5 minutes, and then peeled off. Thereafter, the film was heat-treated in a dryer at 120° C. for 1 minute to obtain a polyvinyl alcohol-based resin film (1) having a thickness of 45 ⁇ m.
• Example 2 A polyvinyl alcohol-based resin film (2) was obtained in the same manner as in Example 1, except that the polyvinyl alcohol-based resin (A1) (bio-derived PVA resin) and the polyvinyl alcohol-based resin (A'1) (petroleum-derived PVA resin) obtained in the above synthesis example were mixed in a mass ratio of 70:30.
• A1 bio-derived PVA resin
• A'1 commercially-derived PVA resin
• Example 3 A polyvinyl alcohol-based resin film (3) was obtained in the same manner as in Example 1, except that the polyvinyl alcohol-based resin (A1) (bio-derived PVA resin) and the polyvinyl alcohol-based resin (A'1) (petroleum-derived PVA resin) obtained in the above synthesis example were mixed in a mass ratio of 80:20.
• Example 4 A polyvinyl alcohol-based resin film (4) was obtained in the same manner as in Example 1, except that the polyvinyl alcohol-based resin (A1) (bio-derived PVA resin) and the polyvinyl alcohol-based resin (A'1) (petroleum-derived PVA resin) obtained in the above synthesis example were mixed in a mass ratio of 10:90.
• Example 5 A polyvinyl alcohol-based resin film (5) was obtained in the same manner as in Example 1, except that the polyvinyl alcohol-based resin (A1) (bio-derived PVA resin) and the polyvinyl alcohol-based resin (A'1) (petroleum-derived PVA resin) obtained in the above synthesis example were mixed in a mass ratio of 25:75.
• Comparative Example 1 A composition was prepared by blending 100 parts by mass of the polyvinyl alcohol-based resin (A'1) (petroleum-derived PVA resin) obtained in the above synthesis example with 12 parts by mass of glycerin (special grade reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a plasticizer (B), to which ion-exchanged water was added so that the concentration of the composition became 19% by mass.
• the composition was then dissolved at 130°C for 1 hour using an autoclave to obtain an aqueous solution of a polyvinyl alcohol-based resin composition.
• the aqueous solution of the polyvinyl alcohol-based resin composition was applied to a chrome plate placed on a hot plate heated to 90° C.
• the total haze was measured using the polyvinyl alcohol-based resin films (1) to (3) and (1') obtained above.
• the peel strength of the film was measured using an aqueous solution of the polyvinyl alcohol-based resin composition obtained above. The results are shown in Table 1 below.
• the polyvinyl alcohol-based resin (A) used to prepare the polyvinyl alcohol-based resin films of Examples 1 to 3 has a biomass ratio of more than 0% as measured by ASTM D6866 (Method B) and contains radioactive carbon C14. As a result, a film with excellent peelability, a film haze of 1.9 or less, and excellent transparency could be obtained.
• the polyvinyl alcohol-based resin (A) used to prepare the polyvinyl alcohol-based resin film of Comparative Example 1 has a biomass ratio of 0% as measured by ASTM D6866 (Method B) and does not contain radioactive carbon C14. Therefore, it is found that the polyvinyl alcohol-based resin film has poor peelability and a total haze of 1.9 or more, resulting in poor transparency.
• the polyvinyl alcohol-based resin films (4), (5), and (1') obtained above were used to measure the total haze.
• a tensile test was performed on the film using the polyvinyl alcohol-based resin aqueous solution obtained above, and the difference between the breaking strength and the yield strength was calculated. The results are shown in Table 2 below.
• the polyvinyl alcohol-based resin (A) used to prepare the polyvinyl alcohol-based resin films of Examples 4 and 5 has a biomass ratio of more than 0% as measured by ASTM D6866 (Method B) and contains radioactive carbon C14. As a result, the difference between the breaking strength and the yield strength was large, the stretching processability was excellent, and the film had a haze of 1.9 or less, making it possible to obtain a film with excellent transparency.
• the polyvinyl alcohol-based resin (A) used to prepare the polyvinyl alcohol-based resin film of Comparative Example 1 has a biomass content of 0% as measured by ASTM D6866 (Method B) and does not contain radioactive carbon C14. For this reason, the difference between the breaking strength and the yield strength is small, the stretching processability is poor, and the total haze is 1.9 or more, indicating that the polyvinyl alcohol-based resin film is poor in transparency.
• the polyvinyl alcohol-based resin film of the present invention is useful for optical applications such as optical films, films with excellent appearance, packaging applications, and water-soluble films.
• the polarizing film obtained from the polyvinyl alcohol-based resin film has no color unevenness and has excellent in-plane uniformity of polarization performance, and is preferably used for, for example, liquid crystal display devices such as portable information terminals, personal computers, televisions, projectors, signage, electronic desk calculators, electronic clocks, word processors, electronic paper, game consoles, videos, cameras, photo albums, thermometers, audio equipment, instruments for automobiles and machinery, sunglasses, anti-glare glasses, stereoscopic glasses, wearable displays, anti-reflection layers for display elements (CRT, LCD, organic EL, electronic paper, etc.), optical communication devices, medical devices, building materials, toys, etc.
• liquid crystal display devices such as portable information terminals, personal computers, televisions, projectors, signage, electronic desk calculators, electronic clocks, word processors, electronic paper, game consoles, videos

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