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
  • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L71/00—Compositions of polyethers obtained by reactions forming an ether link in the main chain; Compositions of derivatives of such polymers
• • 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
• • 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 is a polyvinyl alcohol containing polyvinyl alcohol (A), a nonionic surfactant (B), an anionic surfactant having no carboxyl group (C), and a surfactant having a carboxyl group (D).
• the present invention relates to a film and a method for producing a polarizing film using the film.
• Polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) film is used for various purposes by utilizing its unique properties such as transparency, optical properties, mechanical strength, and water solubility.
• a PVA film is used as a raw material (raw film) for manufacturing a polarizing film that constitutes a polarizing plate that is a basic component of a liquid crystal display (LCD) by utilizing its excellent optical characteristics.
• Raw film raw material
• polarizing film that constitutes a polarizing plate that is a basic component of a liquid crystal display (LCD) by utilizing its excellent optical characteristics.
• LCD liquid crystal display
• Applications are expanding.
• the polarizing plate for LCD is required to have high optical performance, and the polarizing film which is a component thereof is also required to have high optical performance.
• a polarizing plate is generally manufactured by subjecting a raw PVA film to dyeing, uniaxial stretching, and if necessary, fixing treatment with a boron compound or the like to produce a polarizing film, and then producing cellulose triacetate on the surface of the polarizing film. It is manufactured by laminating a protective film such as a (TAC) film.
• the raw PVA film is generally produced by a method such as a cast film forming method in which a PVA-containing stock solution is dried.
• Patent Document 1 the correlation length derived from the result of light scattering measurement using a He—Ne laser having a wavelength of 633 nm as a light source is 200 nm or less, and the content of fatty acid having 10 or more carbon atoms in the film is A polyvinyl alcohol-based film is described which is 1 to 100 ppm. According to this, since the light scatterer in the film has little influence on light in the visible light region, it is possible to obtain a polarizing film having excellent light transmittance by using the polyvinyl alcohol film. ing.
• Patent Document 2 when the film surface is subjected to negative ion analysis with a time-of-flight secondary ion mass spectrometer and the total detection intensity of all negative ions is set to 1, fats having 10 to 30 carbon atoms Polyvinyl wherein the total detection intensity a of the group carboxylic acid fragment ions, the total detection intensity b of the sulfur-containing fragment ions, and the total detection intensity c of the nitrogen-containing fragment ions are in the range of 0.0001 to 0.01. Alcohol-based films are described. According to this, there is no optical unevenness, and it is said that an excellent blocking resistance effect can be exhibited even during storage and transportation in a roll state.
• An object of the present invention is to provide a PVA film having excellent transparency and a method for producing a polarizing film using the PVA film.
• the above-mentioned problem is polyvinyl alcohol containing polyvinyl alcohol (A), nonionic surfactant (B), anionic surfactant (C) having no carboxyl group, and surfactant (D) having carboxyl group.
• a film The content of the nonionic surfactant (B) is 0.01 to 0.12 parts by mass with respect to 100 parts by mass of the polyvinyl alcohol (A), The content of the anionic surfactant (C) is 0.01 to 0.24 parts by mass with respect to 100 parts by mass of the polyvinyl alcohol (A),
• the surfactant (D) is an alkali metal salt or an amine salt, and the content of the surfactant (D) is 0.005 to 0.06 parts by mass with respect to 100 parts by mass of the polyvinyl alcohol (A).
• One solution is to provide a polyvinyl alcohol film.
• the content ratio (B:C) of the nonionic surfactant (B) and the anionic surfactant (C) is preferably 20:80 to 49:51.
• the anionic surfactant (C) is preferably a sulfonate type surfactant
• the surfactant (D) is a polyoxyethylene alkyl ether carboxylic acid represented by the following formula (I).
• the acid salt is preferred.
• R is an alkyl group having 8 to 18 carbon atoms, the number of polyoxyethylene chains (n) is 2 to 10, and M is an alkali metal or an amine.
• the surfactant (D) is an alkylaminocarboxylic acid salt represented by the following formula (II) or an alkylimide dicarboxylic acid salt represented by the following formula (III).
• R is an alkyl group having 8 to 18 carbon atoms, n is 1 to 3, and M is an alkali metal or an amine.
• the surfactant (D) is alkyl dimethyl betaine represented by the following formula (IV).
• R represents an alkyl group having 8 to 18 carbon atoms.
• the surfactant (D) is preferably an alkali metal salt or amine salt of a fatty acid having 12 or more carbon atoms.
• the film width is preferably 1.5 m or more, and the film length is preferably 3000 m or more. It is also preferable that the film thickness is 10 to 70 ⁇ m.
• the above problems can also be solved by providing a method for producing a polarizing film having a step of dyeing and a step of stretching the polyvinyl alcohol film.
• a good quality PVA film having a small number of optical defects, optical spots, and activator aggregates and a low haze value can be obtained. Therefore, by using the PVA film as a raw fabric, a polarizing film having excellent in-plane uniformity and light transmittance can be obtained.
• the PVA film of the present invention contains PVA (A), a nonionic surfactant (B), an anionic surfactant having no carboxyl group (C), and a surfactant having a carboxyl group (D). ..
• the present inventors provide a PVA film containing PVA (A), a nonionic surfactant (B), an anionic surfactant (C), and a surfactant (D) having a carboxyl group in a fixed amount.
• the surfactant (D) is an alkali metal salt or an amine salt, a PVA film of good quality having a small number of optical defects, optical spots and aggregates of an active agent and a low haze value can be obtained. I found that And it became clear that a polarizing film excellent in in-plane uniformity and light transmittance can be obtained by using such a PVA film.
• the present inventors have found that when the contents of PVA (A), nonionic surfactant (B), anionic surfactant (C) and surfactant (D) are not within a certain range, good quality PVA is obtained. It was confirmed that a film could not be obtained, and the in-plane uniformity and light transmittance when processed into a polarizing film were poor. Further, the present inventors have found that when the surfactant (D) having a carboxyl group is an aliphatic carboxylic acid instead of an alkali metal salt or an amine salt, the number of activator aggregates is large and the haze value is large. It is confirmed that the light transmittance is low when processed into a polarizing film.
• PVA (A), nonionic surfactant (B), anionic surfactant (C), and surfactant (D) having a carboxyl group are each contained in a fixed amount, and It is important that the surfactant (D) is a PVA film in which an alkali metal salt or an amine salt is used.
• the PVA film has a small number of optical defects, optical spots and activator aggregates, a low haze value, and excellent in-plane uniformity and light transmittance when processed into a polarizing film. Can be obtained.
• PVA (A) As the PVA (A), a product produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester can be used.
• the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate and the like. These may be used alone or in combination of two or more, but the former is preferred.
• Vinyl acetate is preferable as the vinyl ester from the viewpoints of availability, cost, PVA (A) productivity, and the like.
• Other monomers copolymerizable with vinyl ester include, for example, ethylene; olefins having 3 to 30 carbon atoms such as propylene, 1-butene, and isobutene; acrylic acid or salts thereof; methyl acrylate, ethyl acrylate, acrylic acid Acrylic esters such as n-propyl, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methacryl Acids or salts thereof; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexy
• Methacrylic acid esters such as dodecyl methacrylate and octadecyl methacrylate; acrylamide, N-methyl acrylamide, N-ethyl acrylamide, N,N-dimethyl acrylamide, diacetone acrylamide, acrylamide propane sulfonic acid or its salt, acrylamide propyl dimethyl amine or Acrylamide derivatives such as salts thereof, N-methylolacrylamide or derivatives thereof; methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or salts thereof, methacrylamidepropyldimethylamine or salts thereof, N- Methacrylic amide derivatives such as methylol methacrylamide or derivatives thereof; N-vinyl amides such as N-vinyl formamide, N-vinyl acetamide, N-vinyl pyrrolidone; methyl vinyl ether, ethyl vinyl
• These other monomers may be used alone or in combination of two or more. Among them, ethylene and olefins having 3 to 30 carbon atoms are preferable as the other monomer, and ethylene is more preferable.
• the ratio of the structural units derived from the other monomer in the vinyl ester polymer is not particularly limited, but is 15 mol% or less based on the number of moles of all structural units constituting the vinyl ester polymer. It is preferably 5 mol% or less, and more preferably 5 mol% or less.
• the degree of polymerization of PVA (A) is not necessarily limited, but it is preferably 200 or more, more preferably 300 or more, and further preferably 400 or more because the film strength tends to decrease as the polymerization degree decreases. It is particularly preferably 500 or more. Further, if the polymerization degree is too high, the viscosity of the aqueous solution of PVA (A) or the melted PVA (A) tends to be high, and film formation tends to be difficult, so that it is preferably 10,000 or less, and more preferable. Is preferably 9,000 or less, more preferably 8,000 or less, and particularly preferably 7,000 or less.
• the degree of polymerization of PVA (A) means the average degree of polymerization measured according to the description of JIS K6726-1994, and the degree of polymerization of PVA (A) is measured again in water at 30° C. after resaponification and purification.
• the degree of saponification of PVA (A) is not particularly limited, and for example, 60 mol% or more of PVA (A) can be used. However, from the viewpoint of use as a raw film for producing an optical film such as a polarizing film, PVA (PVA) is used.
• the degree of saponification of (A) is preferably 95 mol% or more, more preferably 98 mol% or more, still more preferably 99 mol% or more.
• the degree of saponification of PVA (A) means the total number of moles of structural units (typically vinyl ester-based monomer units) and vinyl alcohol units that PVA (A) can convert into vinyl alcohol units by saponification. In contrast, the ratio (mol %) occupied by the number of moles of the vinyl alcohol unit.
• the degree of saponification of PVA (A) can be measured according to the description of JIS K6726-1994.
• PVA (A) one type of PVA may be used alone, or two or more types of PVA having different degrees of polymerization, degree of saponification, degree of modification and the like may be used in combination.
• the PVA film has a PVA having an acidic functional group such as a carboxyl group or a sulfonic acid group; a PVA having an acid anhydride group; a PVA having a basic functional group such as an amino group;
• PVA having a functional group that promotes the above is contained, the secondary processability of the PVA film may be deteriorated due to a crosslinking reaction between PVA molecules.
• PVA (A) having an acidic functional group PVA having an acid anhydride group
• basic The content of PVA having a functional group and the neutralized product thereof is preferably 0.1% by mass or less, and more preferably none of them is contained.
• the content of PVA (A) in the PVA film is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 85% by mass or more.
• the content of PVA (A) is usually 90% by mass or less.
• Nonionic surfactant (B) used in the present invention is not particularly limited, but it is an alkyl ether type such as polyoxyethylene oleyl ether; an alkylphenyl ether type such as polyoxyethylene octylphenyl ether; a polyoxyethylene laurate etc. Alkyl ester type; polyoxyethylene lauryl amino ether, etc. alkylamine type; polyoxyethylene lauric acid amide, etc. alkylamide type; polyoxyethylene polyoxypropylene ether, etc.
• alkyl ether type such as polyoxyethylene oleyl ether
• an alkylphenyl ether type such as polyoxyethylene octylphenyl ether
• Alkyl ester type polyoxyethylene lauryl amino ether, etc. alkylamine type
• polyoxyethylene lauric acid amide, etc. alkylamide type polyoxyethylene polyoxypropylene ether, etc.
• the aliphatic alkanolamide type is more preferably used as the nonionic surfactant (B).
• B the nonionic surfactant
• a secondary amide type aliphatic alkanolamide represented by the following formula (V) is more preferably used.
• R is an alkyl group having 8 to 18 carbon atoms, and the number of polyoxyethylene chains (n) is 2 to 10].
• R is an alkyl group having 8 to 18 carbon atoms.
• the alkyl group may be linear or branched, but is preferably linear.
• the carbon number (alkyl chain length) of R is preferably 9 or more, and more preferably 10 or more.
• the carbon number (alkyl chain length) of R is preferably 15 or less, and more preferably 13 or less.
• the number of polyoxyethylene chains (n) is 2-10. If the number of polyoxyethylene chains (n) is less than 2, problems such as a large number of activator aggregates in the PVA film and a high haze value may occur.
• the polyoxyethylene chain number (n) is preferably 4 or more. On the other hand, when the number of polyoxyethylene chains (n) is more than 10, many optical defects may occur in the PVA film.
• the polyoxyethylene chain number (n) is preferably 8 or less.
• the content of the nonionic surfactant (B) is 0.01 to 0.12 parts by mass with respect to 100 parts by mass of PVA (A).
• the content of the nonionic surfactant (B) is preferably 0.02 or more, more preferably 0.03 or more.
• the content of the nonionic surfactant (B) exceeds 0.12 parts by mass, there arise problems that the number of activator aggregates in the PVA film increases and the haze value increases.
• the content of the nonionic surfactant (B) is preferably 0.1 part by mass or less, more preferably 0.08 part by mass or less, and further preferably 0.06 part by mass or less. ..
• the nonionic surfactant (B) used in the present invention may be used alone or in combination of two or more.
• the anionic surfactant (C) used in the present invention does not have a carboxyl group, and is preferably at least one selected from the group consisting of sulfate ester type and sulfonate type.
• Examples of the sulfate ester salt type include sodium alkyl sulfate, potassium alkyl sulfate, ammonium alkyl sulfate, triethanolamine alkyl sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxypropylene alkyl ether sulfate, and sodium polyoxyethylene alkylphenyl ether sulfate.
• the alkyl is preferably an alkyl having 8 to 20 carbons, and more preferably an alkyl having 10 to 16 carbons.
• Examples of the sulfonate type include sodium alkyl sulfonate, potassium alkyl sulfonate, ammonium alkyl sulfonate, triethanolamine alkyl sulfonate, sodium alkylbenzene sulfonate, disodium dodecyl diphenyl ether disulfonate, sodium alkylnaphthalene sulfonate, alkyl sulfosuccinate. Examples thereof include disodium acid salt and disodium polyoxyethylene alkylsulfosuccinate.
• the alkyl is preferably an alkyl having 8 to 20 carbons, and more preferably an alkyl having 10 to 16 carbons.
• the anionic surfactant (C) is preferably a sulfonate type from the viewpoint that the number of aggregates of the active agent is small and the haze value is low.
• the content of the anionic surfactant (C) is 0.01 to 0.24 parts by mass with respect to 100 parts by mass of PVA (A).
• the content of the anionic surfactant (C) is preferably 0.02 parts by mass or more, and more preferably 0.03 parts by mass or more.
• the content of the anionic surfactant (C) is preferably 0.18 or less, more preferably 0.16 parts by mass or less, further preferably 0.14 parts by mass or less, and 0 It is particularly preferable that the amount is 0.12 parts by mass or less.
• the content ratio (B:C) of the nonionic surfactant (B) and the anionic surfactant (C) is preferably 20:80 to 49:51.
• the content ratio (B:C) is less than 20:80, many optical defects may occur in the PVA film.
• the content mass ratio (B:C) is more preferably 25:75 or more, further preferably 30:70 or more.
• the content ratio (B:C) is more preferably 47:53 or less, further preferably 45:55 or less.
• the surfactant (D) used in the present invention has a carboxyl group and is composed of an alkali metal salt or an amine salt.
• the present inventors have found that when an aliphatic carboxylic acid is used instead of an alkali metal salt or an amine salt, the number of activator aggregates is large, the haze value is high, and light transmission when processed into a polarizing film. It is confirmed that the sex is inferior. Therefore, it is important that the surfactant (D) has a carboxyl group and is an alkali metal salt or an amine salt.
• the alkali metal is preferably at least one selected from the group consisting of lithium, sodium, potassium and cesium, and more preferably at least one selected from the group consisting of sodium and potassium.
• the amine is preferably at least one selected from the group consisting of ammonia, monomethanolamine, monoethanolamine, diethanolamine and triethanolamine, and more preferably diethanolamine.
• the surfactant (D) used in the present invention includes a polyoxyethylene alkyl ether carboxylate represented by the following formula (I), an alkylaminocarboxylate represented by the following formula (II), and a following formula ( At least one selected from the group consisting of an alkylimide dicarboxylic acid salt represented by III), an alkyldimethyl betaine represented by the following formula (IV), and an alkali metal salt or amine salt of a fatty acid having 12 or more carbon atoms. It is preferable to have.
• R is an alkyl group having 8 to 18 carbon atoms, the number of polyoxyethylene chains (n) is 2 to 10, and M is an alkali metal or an amine. ]
• R is an alkyl group having 8 to 18 carbon atoms, n is 1 to 3, and M is an alkali metal or an amine.
• R represents an alkyl group having 8 to 18 carbon atoms.
• R is an alkyl group having 8 to 18 carbon atoms.
• the alkyl group may be linear or branched, but is preferably linear.
• the carbon number of R (alkyl chain length) of R is preferably 9 or more, and more preferably 10 or more.
• M is an alkali metal or amine. As the specific alkali metal or amine, the above-mentioned ones can be preferably used.
• the number of polyoxyethylene chains (n) is 2-10.
• the polyoxyethylene chain number (n) is preferably 4 or more.
• the number of polyoxyethylene chains (n) exceeds 10, the amount of segregation on the film surface is small and the optical unevenness may become large.
• the polyoxyethylene chain number (n) is preferably 8 or less.
• n in the above formulas (II) and (III) is preferably 2 to 3.
• an alkali metal salt or amine salt of a fatty acid having 12 or more carbon atoms is also suitably used as the surfactant (D).
• the carbon chain of the fatty acid may be linear or branched, but is preferably linear.
• the number of carbon atoms in the fatty acid is preferably 18 or less, more preferably 16 or less.
• the fatty acid may be saturated fatty acid or unsaturated fatty acid, but saturated fatty acid is preferable.
• Specific examples of the alkali metal salt or amine salt of a fatty acid having 12 or more carbon atoms include alkali metal salts or amine salts of lauric acid, myristic acid, pentadecyl acid, palmitic acid, stearic acid and the like.
• an alkali metal salt or amine salt of at least one fatty acid selected from the group consisting of lauric acid, myristic acid, pentadecyl acid and palmitic acid is more preferably used as the surfactant (D).
• the specific alkali metal or amine the above-mentioned ones can be preferably used.
• the content of the surfactant (D) is 0.005 to 0.06 parts by mass with respect to 100 parts by mass of PVA (A).
• the content of the surfactant (D) is preferably 0.008 parts by mass or more, and more preferably 0.01 parts by mass or more.
• the content of the surfactant (D) exceeds 0.06 parts by mass, there arises a problem that the number of aggregates of the surfactant increases and the haze value increases.
• the content of the surfactant (D) is preferably 0.05 part by mass or less, more preferably 0.04 part by mass or less, and further preferably 0.03 part by mass or less.
• the PVA film of the present invention preferably contains a plasticizer.
• plasticizers include polyhydric alcohols, and specific examples thereof include ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane. These may use only 1 type of plasticizer, and may use 2 or more types of plasticizers together. Among them, ethylene glycol or glycerin is preferable from the viewpoint of compatibility with PVA (A) and availability.
• the content of the plasticizer is preferably in the range of 1 to 30 parts by mass with respect to 100 parts by mass of PVA (A).
• the content of the plasticizer is 1 part by mass or more, problems with mechanical properties such as impact strength and process passability during secondary processing are less likely to occur.
• the content of the plasticizer is 30 parts by mass or less, the film becomes moderately flexible and the handleability is improved.
• the PVA film of the present invention contains PVA (A), a nonionic surfactant (B), an anionic surfactant (C), a surfactant (D) and a component other than a plasticizer, if necessary. Further, it may be contained.
• PVA a nonionic surfactant
• anionic surfactant C
• surfactant D
• a component other than a plasticizer if necessary. Further, it may be contained.
• other components include water, antioxidants, ultraviolet absorbers, lubricants, colorants, fillers (inorganic particles/starch, etc.), preservatives, antifungal agents, and components other than the above-mentioned components. Examples thereof include polymer compounds.
• the content of other components in the PVA film is preferably 10% by mass or less.
• the width of the PVA film of the present invention there is no particular limitation on the width of the PVA film of the present invention. Since a polarizing film having a wide width is required in recent years, the width is preferably 1.5 m or more. Further, if the width of the PVA film is too wide, the manufacturing cost of the film forming apparatus for forming the PVA film increases, and further, when the optical film is manufactured by a practically used manufacturing apparatus, it is uniform. The width of the PVA film is usually 7.5 m or less because it may be difficult to stretch the PVA film.
• the shape of the PVA film of the present invention is not particularly limited, but it is long because of the fact that a more uniform PVA film can be continuously and smoothly produced, and that it is continuously used when producing an optical film or the like. It is preferably a full length film.
• the length of the long film (length in the flow direction) is not particularly limited and can be set appropriately.
• the length of the film is preferably 3000 m or more.
• the length of the film is preferably 30,000 m or less.
• a long film is preferably wound into a core to form a film roll.
• the thickness of the PVA film of the present invention is not particularly limited and can be set appropriately.
• the thickness of the film is preferably 10 to 70 ⁇ m from the viewpoint of use as a raw film for producing an optical film such as a polarizing film.
• the thickness of the PVA film can be obtained as an average value of values measured at arbitrary 10 places.
• the haze of the PVA film of the present invention and the number of activator aggregates are measured by the methods described in the examples below.
• the haze value is preferably 0.4 or less, more preferably 0.3 or less, and further preferably 0.2 or less.
• the number of such activator aggregates is preferably 140 or less, more preferably 120 or less, and further preferably 110 or less.
• the method for producing the PVA film of the present invention is not particularly limited.
• a method of manufacturing which comprises mixing PVA (A), a nonionic surfactant (B), an anionic surfactant (C), and a surfactant (D) to prepare a stock solution for film formation
• the method is a method for producing a PVA film, which comprises a step of forming a film using a film forming solution.
• a liquid medium can be further mixed in the step of preparing the film-forming stock solution.
• the liquid medium at this time include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, ethylenediamine, Examples thereof include diethylenetriamine, and one or more of these can be used. Among them, water is preferable from the viewpoints of low environmental load and recoverability.
• PVA (A) nonionic surfactant (B), anionic surfactant (C), surfactant (D), liquid medium
• a known method such as a casting film forming method or a melt extrusion film forming method can be adopted by using the film forming stock solution containing the above-mentioned plasticizer and other components.
• the film-forming stock solution may be PVA (A) dissolved in a liquid medium or may be PVA (A) melted.
• the volatile content ratio of the stock solution for film formation (content ratio of volatile components such as liquid medium removed by volatilization or evaporation during film formation in the stock solution for film formation) varies depending on the film forming method, film forming conditions, etc. It is preferably in the range of 90% by mass, more preferably in the range of 55 to 80% by mass.
• the volatile content of the film-forming stock solution is 50% by mass or more, the viscosity of the film-forming stock solution does not become too high, and film formation is facilitated.
• the volatile matter content of the film-forming stock solution is 90 mass% or less, the thickness uniformity of the PVA film obtained can be improved without the viscosity of the film-forming stock solution becoming too low.
• the PVA film of the present invention is preferably produced by the casting film forming method or the melt extrusion film forming method using the above film forming solution.
• the specific manufacturing method at this time is not particularly limited, and for example, it is obtained by casting or discharging the film-forming stock solution in the form of a film on a support such as a drum or a belt, and drying on the support. You can If necessary, the obtained film may be further dried by a drying roll or a hot air drying device, may be heat-treated by a heat treatment device, or may be moisture-conditioned by a humidity control device.
• the manufactured PVA film is preferably wound into a core to form a film roll. Further, both ends in the width direction of the manufactured PVA film may be cut off.
• the PVA film of the present invention can be suitably used as a raw film for producing a polarizing film, a retardation film, a special light condensing film and the like. According to the present invention, it is possible to obtain a PVA film having excellent in-plane uniformity and light transmittance and high quality. Therefore, the optical PVA film is a preferred embodiment of the present invention.
• a preferred embodiment of the present invention is a method for producing a polarizing film having a step of dyeing the PVA film and a step of stretching.
• the manufacturing method may further include a fixing treatment step, a drying treatment step, a heat treatment step, and the like.
• the order of dyeing and stretching is not particularly limited, and the dyeing treatment may be performed before the stretching treatment, the dyeing treatment may be performed simultaneously with the stretching treatment, or the dyeing treatment may be performed after the stretching treatment. .. Further, the steps such as stretching and dyeing may be repeated multiple times. Particularly, it is preferable to divide the drawing into two or more stages because uniform drawing can be easily performed.
• Dyes used for dyeing PVA films include iodine or dichroic organic dyes (for example, DirectBlack 17, 19, 154; DirectBrown 44, 106, 195, 210, 223; DirectRed 2, 23, 28, 31, 37, 39). , 79, 81, 240, 242, 247; DirectBlue 1, 15, 22, 78, 90, 98, 151, 168, 202, 236, 249, 270; DirectViolet 9, 12, 51, 98; DirectGreen 1, 85; Direct Yellow 8, 12, 44, 86, 87; dichroic dyes such as Direct Orange 26, 39, 106, 107) and the like can be used. These dyes can be used alone or in combination of two or more. Dyeing can usually be performed by immersing the PVA film in a solution containing the above dye, but the treatment conditions and treatment method are not particularly limited.
• the uniaxial stretching for stretching the PVA film in the machine direction (MD) or the like may be performed by either a wet stretching method or a dry heat stretching method, but the wet stretching method is used from the viewpoint of stability of performance and quality of the obtained polarizing film. Is preferred.
• the wet stretching method include a method of stretching a PVA film in pure water, an aqueous solution containing various components such as additives and water-soluble organic solvents, or an aqueous dispersion liquid in which various components are dispersed.
• the uniaxial stretching method by the wet stretching method include a method of uniaxially stretching in warm water containing boric acid, a method of uniaxially stretching in a solution containing the dye or in a fixing treatment bath described later.
• the PVA film after absorbing water may be uniaxially stretched in the air, or may be uniaxially stretched by another method.
• the stretching temperature during uniaxial stretching is not particularly limited, but in the case of wet stretching, a temperature within the range of preferably 20 to 90°C, more preferably 25 to 70°C, further preferably 30 to 65°C is adopted, and dry stretching is performed. In the case of hot stretching, a temperature within the range of 50 to 180° C. is preferably adopted.
• the stretching ratio of the uniaxial stretching treatment is preferably as much as possible until just before the film is cut from the viewpoint of polarization performance, specifically, 4 times or more. Is more preferable, 5 times or more is more preferable, and 5.5 times or more is further preferable.
• the upper limit of the stretching ratio is not particularly limited as long as the film is not broken, but it is preferably 8.0 times or less in order to perform uniform stretching.
• the fixing treatment a general method of immersing the PVA film in a treatment bath to which boric acid and/or a boron compound is added can be adopted. At that time, an iodine compound may be added to the treatment bath if necessary.
• the PVA film that has been uniaxially stretched or uniaxially stretched and fixed is then subjected to drying treatment or heat treatment.
• the temperature of the drying treatment or heat treatment is preferably 30 to 150°C, and particularly preferably 50 to 140°C. If the temperature is too low, the dimensional stability of the obtained polarizing film tends to decrease. On the other hand, if the temperature is too high, the polarization performance is likely to deteriorate due to decomposition of the dye.
• a protective film that is optically transparent and has mechanical strength can be attached to both sides or one side of the polarizing film obtained as described above to form a polarizing plate.
• a cellulose triacetate (TAC) film, an acetic acid/cellulose butyrate (CAB) film, an acrylic film, a polyester film, or the like is used as the protective film.
• a PVA-based adhesive or a urethane-based adhesive is generally used, and among them, the PVA-based adhesive is preferably used.
• the polarizing plate obtained as described above can be used as a component of a liquid crystal display device after being coated with an adhesive such as an acrylic resin and then attached to a glass substrate.
• an adhesive such as an acrylic resin
• a retardation film, a viewing angle improving film, a brightness improving film and the like may be attached at the same time.
• the optical spots were evaluated by measuring the retardation (Re) of the PVA film. Specifically, a sample piece of MD100 cm ⁇ TD30 cm (thickness 60 ⁇ m) was cut out from the TD-direction central portion of the PVA film rolls obtained in the following Examples and Comparative Examples, and further divided into four in the MD direction, The retardation (Re) was measured using a birefringence evaluation device. The maximum value and the minimum value of the retardation (Re) in the region of MD 100 cm ⁇ TD 30 cm were used as the index of optical spots, and evaluated according to the following criteria. A: The difference between the maximum value and the minimum value of Re is small and the level is suitable for products. B: A level where the difference between the maximum value and the minimum value of Re is large and is not suitable for products.
• Method for measuring the number of activator aggregates A region of 10 m from the surface layer side of the PVA film roll to be measured was cut out, and a sample piece of MD50 mm ⁇ TD50 mm (thickness 60 ⁇ m) was collected from an arbitrary position. Images of the collected samples were taken at positions of about 1 ⁇ m in the film thickness direction using a microscope VHX6000 manufactured by Keyence Corporation (magnification is 1000 times), and the number of activator aggregates reflected in the taken images was counted. ..
• the conditions for each of the above processes are as follows.
• the swelling treatment the PVA film was immersed in distilled water (temperature: 30° C.) for 1 minute, and during that time, it was uniaxially stretched in the length direction (MD) to 2.0 times the original length.
• a dyeing treatment it is immersed for 1 minute in an aqueous solution containing an iodine dye (iodine concentration: 0.02 to 0.05% by mass, potassium iodide concentration: 1.0% by mass, temperature: 32° C.), Meanwhile, it was uniaxially stretched in the length direction (MD) to 2.5 times the original length.
• an iodine dye iodine concentration: 0.02 to 0.05% by mass, potassium iodide concentration: 1.0% by mass, temperature: 32° C.
• the transmittance of light when tilted at 45° with respect to the vertical direction and the transmittance of light when tilted at ⁇ 45° were measured, and an average value Ts1 (%) thereof was obtained.
• the light transmittance when tilted at 45° and the light transmittance when tilted at ⁇ 45° were measured, and their average value Ts2 (%) was determined.
• the transmittance Ts (%) of the polarizing film was calculated by averaging Ts1 and Ts2 by the following formula (1).
• Ts (Ts1+Ts2)/2 (1) (C) Measurement of Degree of Polarization V
• Light transmittance T ⁇ (%) and length of light when two samples collected in the above measurement of transmittance Ts are overlapped so that their length directions are parallel to each other, and The light transmittance T ⁇ (%) in the case where the light beams are overlapped so that the vertical directions are orthogonal to each other is measured in the same manner as in the above-mentioned “(b) Measurement of transmittance Ts”, and the polarization degree is calculated by the following formula (2). V (%) was calculated.
• Example 1 As PVA (A), chips of PVA (saponification product of homopolymer of vinyl acetate) having a degree of polymerization of 2400 and a degree of saponification of 99.9 mol% were used. After immersing 100 parts by mass of the PVA chip in 2500 parts by mass of distilled water at 35° C., centrifugal dehydration was performed to obtain a PVA water-containing chip having a volatile content of 60% by mass.
• PVA PVA
• the nonionic surfactant (B) used at this time was a polyoxyethylene fatty acid monoalkanolamide (having 12 carbon atoms in the alkyl group and 6 ethylene oxide additions (n)), and the anionic surfactant (B).
• C) was sodium alkyl sulfonate (having 15 carbon atoms in the alkyl group), and surfactant (D) having a carboxyl group was sodium imidodicarboxylate (R has 12 carbon atoms and n is 2). ..
• This stock solution for film formation was cooled to 100° C. by a heat exchanger, then extruded into a film having a surface temperature of 90° C. from a coat hanger die having a width of 180 cm, and further dried using a hot air dryer, and then, A PVA film having a thickness of 60 ⁇ m and a width of 165 cm was continuously manufactured by cutting off both ends of the film thickened by neck-in during film formation. Then, a length of 4000 m of the manufactured PVA film was wound on a cylindrical core to obtain a film roll. With respect to the obtained PVA film, the number of optical defects, optical spots, haze, and activator aggregates was evaluated by the methods described above. In addition, a polarizing film was manufactured using the obtained PVA film, and in-plane uniformity and light transmittance were evaluated as polarizing performance. The results are shown in Table 1.
• Example 2-10 Comparative Examples 1-8 Example 1 except that the types and amounts of the nonionic surfactant (B), anionic surfactant (C) and carboxyl group-containing surfactant (D) were changed as shown in Table 1. Similarly, a PVA film was produced and evaluated.
• the nonionic surfactant used in Example 3 was a tertiary amide type lauric acid diethanolamide, and the anionic surfactant (C) used in Example 4 was a sulfate ester type polyoxyethylene.
• the surfactant (D) having sodium lauryl ether sulfate (having 12 carbon atoms in the alkyl group and 3 additions of ethylene oxide) and having a carboxyl group used in Example 5 was sodium polyoxyethylene alkyl ether carboxylate. (R has 12 carbon atoms and n is 6), and the surfactant (D) having a carboxyl group used in Example 6 is alkyl dimethyl betaine (R has 12 carbon atoms).
• the PVA films of Examples 1 to 10 had a small number of optical defects, optical spots, and activator aggregates, a low haze value, and good quality. Further, the PVA films of Examples 1 to 10 were excellent in the in-plane uniformity and light transmittance of the polarizing film. On the other hand, many optical defects occurred in the PVA films of Comparative Example 1 containing a small amount of nonionic surfactant (B) and Comparative Example 4 containing a large amount of anionic surfactant (C).
• Comparative Example 2 containing a large amount of nonionic surfactant (B), Comparative Example 3 containing a small amount of anionic surfactant (C), Comparative Example 6 containing a large amount of surfactant (D) having a carboxyl group, and surfactant having a carboxyl group.
• PVA film of Comparative Example 8 not using the anionic surfactant (C) and using lauric acid as the surfactant (D) having a carboxyl group.
• the PVA film of Comparative Example 5 containing a small amount of the carboxyl group-containing surfactant (D) had large optical spots, and the in-plane uniformity of the polarizing film was not good.

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