Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J167/00—Adhesives based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Adhesives based on 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
• • 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
  • 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
  • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
• • 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
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
  • C09J7/22—Plastics; Metallised plastics
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/14—Protective coatings, e.g. hard coatings
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
• • 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
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
  • C09J2203/318—Applications of adhesives in processes or use of adhesives in the form of films or foils for the production of liquid crystal displays
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
  • C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2429/00—Presence of polyvinyl alcohol
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2467/00—Presence of polyester
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2467/00—Presence of polyester
  • C09J2467/006—Presence of polyester in the substrate
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/133528—Polarisers
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
  • G02F2201/50—Protective arrangements
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F2202/00—Materials and properties
  • G02F2202/28—Adhesive materials or arrangements

Definitions

• the present invention relates to an easily adhesive polyester film for protecting a polarizer used for protecting a polarizer.
• it is related with the easily-adhesive polyester film for polarizer protection excellent in adhesiveness with a polarizer.
• polarizing plates are arranged on both sides of a glass substrate that forms the surface of the liquid crystal panel due to the image forming method.
• the polarizing plate generally has a configuration in which a polarizer protective film is bonded to both surfaces of a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine via a hydrophilic adhesive such as a polyvinyl alcohol resin.
• a protective film used for protecting a polarizer a triacetyl cellulose film has been conventionally used from the viewpoint of optical properties and transparency.
• triacetyl cellulose is not sufficiently durable, and when a polarizing plate using a triacetyl cellulose film as a polarizer protective film is used at high temperature or high humidity, the performance of the polarizing plate such as the degree of polarization and the hue deteriorates. There is a case. In recent years, there has been a demand for thinning the polarizing plate in order to cope with the thinning of the display. However, from the viewpoint of maintaining moisture barrier properties, there has been a limit to thinning the triacetyl cellulose film. Accordingly, it has been proposed to use a polyester film as a polarizer protective film having durability and moisture barrier properties (see Patent Documents 1 to 5).
• the triacetyl cellulose film used as a polarizer protective film is subjected to alkali treatment on the surface, and has an extremely high affinity with a hydrophilic adhesive. Therefore, the protective film made of a triacetyl cellulose film has extremely high adhesiveness with a polarizer coated with a hydrophilic adhesive.
• the polyester film has insufficient adhesion to the hydrophilic adhesive, and this tendency becomes more prominent particularly in the case of a polyester film having orientation by a stretching treatment. Therefore, Patent Documents 1 to 3 and 5 propose providing a polyester film with an easy-adhesion layer in order to improve the adhesion to the polarizer or the hydrophilic adhesive applied to the polarizer.
• the polyester film has a low affinity for water, and this tendency is particularly remarkable in the polyester film having an aromatic dicarboxylic acid as a dicarboxylic acid component. Moreover, the polyester film which has crystal orientation by extending
• the polarizer and the adhesive applied on the polarizer are mainly composed of a polyvinyl alcohol-based resin and have high hydrophilicity. Due to the difference in properties, the polyester film, the polarizer, and the adhesive have low affinity, and it has been difficult to firmly bond the two. Therefore, even the polyester film having the easy-adhesion layer disclosed in Patent Documents 1 to 3 and 5 has not yet obtained sufficient adhesion as compared with the triacetyl cellulose film.
• an object of the present invention is to provide a polyester film provided with means for firmly bonding the polyester film and a polarizer or a polyvinyl alcohol-based resin layer such as an adhesive applied on the polarizer. For the purpose.
• the inventors of the present invention have made extensive studies and examinations to solve the above problems, and have a polyester resin having a high affinity with a polyester film and a polyvinyl alcohol resin having a high affinity with a polyvinyl alcohol resin layer and a crosslinking agent. It came to the idea of providing the layer to contain between a polyester film and a polyvinyl alcohol-type resin layer. However, the present inventors have found that the function of closely adhering the polyester film and the polyvinyl alcohol-based resin layer due to each component cannot be sufficiently exhibited by simply combining these components.
• the present inventors adopted a polyester resin having a certain acid value as the polyester resin in the above concept, and further, polyvinyl alcohol having a certain degree of saponification as the polyvinyl alcohol resin. It has been found that by using a system resin, it is possible to effectively exert the adhesive action of each component with a resin layer having high affinity.
• the present inventors have adopted a cross-linking agent having high reactivity with a hydroxyl group, so that a polyester film and a polyvinyl alcohol resin layer such as a polarizer and an adhesive are used. It has been found that it is possible to adhere to each other more firmly. Based on these findings, the present inventors have made further investigations and improvements and invented the present invention. *
• the 1st invention is a polyester film which has an easily bonding layer on at least one surface,
• the said easily bonding layer contains a polyester-type resin (A), a polyvinyl alcohol-type resin (B), and a crosslinking agent (C),
• the polyester resin (A) has an acid value of 20 KOH mg / g or less, and the polyvinyl alcohol resin (B) has a saponification degree of 60 to 85 mol%.
• the second invention is the above-mentioned easily adhesive polyester film for protecting a polarizer, wherein the polyester resin (A) contains a 5-sulfoisophthalic acid component in an amount of 1 to 15 mol% in the dicarboxylic acid component.
• 3rd invention is the said easily adhesive polyester film for polarizer protection whose said crosslinking agent (C) is an isocyanate compound or a melamine compound.
• the mass ratio of the polyester resin (A), the polyvinyl alcohol resin (B) and the cross-linking agent (C) satisfies the following formula: It is a polyester film. 0.8 ⁇ (A) / (B) ⁇ 5 2 ⁇ ((A) + (B)) / (C) ⁇ 50
• 5th invention is a polarizing plate which has a polarizer protective film on both surfaces of a polarizer, Comprising: The polarizing plate whose polarizer protective film of at least one surface is the said easily-adhesive polyester film for polarizer protection It is.
• the easy-adhesive polyester film for protecting a polarizer of the present invention is excellent in adhesion to a polarizer or a polyvinyl alcohol-based resin layer typified by an adhesive applied thereon. Therefore, the polyester film of the present invention can be suitably used as a protective film for a polarizer.
• a polyester film of the present invention As a protective film for a polarizer, it is possible to produce a polarizing plate having superior durability and water barrier properties at a lower cost than before.
• the polarizing plate of the present invention is excellent in durability, it can be made thinner than before. Therefore, it is possible to further reduce the thickness of the liquid crystal display by using the polarizing plate of the present invention.
• the polyester film used as a substrate in the present invention is a film mainly composed of a polyester resin.
• a film mainly composed of a polyester resin is a film formed from a resin composition containing 50% by mass or more of a polyester resin. When blended with another polymer, the polyester resin is 50% by mass. % When it is copolymerized with other monomers, it means that 50 mol% or more of the polyester structural unit is contained.
• the polyester film contains a polyester resin in an amount of 90% by mass or more, more preferably 95% by mass or more, and still more preferably 100% by mass.
• the material of the polyester resin is not particularly limited, but a copolymer formed by polycondensation of a dicarboxylic acid component and a diol component or a blend resin thereof can be used.
• the dicarboxylic acid component include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, diphenyl Carboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydro Isophthalic
• diol component constituting the polyester resin examples include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1,3- Examples thereof include propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone.
• the dicarboxylic acid component and the diol component constituting the polyester resin may be used alone or in combination of two or more. Further, other acid components such as trimellitic acid and other hydroxyl components such as trimethylolpropane may be appropriately added.
• polyester resin examples include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.
• polyethylene terephthalate is preferable from the balance of physical properties and cost.
• other copolymer components or other polymers are included.
• Preferred copolymer components from the viewpoint of controlling the optical properties of the polyester film include diethylene glycol and copolymer components having norbornene in the side chain.
• the polyester film of the present invention is used as a protective film for a polarizer, it preferably has high transparency.
• the transparency of the polyester film for protecting a polarizer of the present invention is preferably such that the total light transmittance is 85% or more, more preferably 87% or more, still more preferably 88% or more, and even more preferably 89% or more. 90% or more is particularly preferable.
• the haze is preferably 3% or less, more preferably 2.5% or less, further preferably 2% or less, and particularly preferably 1.5% or less.
• the total light transmittance of a polyester film can be measured according to the method described in the Example mentioned later, for example.
• inert particles may be included in the film.
• the inert particles in the film may be included.
• the content is preferably as low as possible. Therefore, a multilayer structure in which particles are included only in the surface layer of the film, or particles are substantially not included in the film, and particles are included only in the easy-adhesion layer laminated on at least one side of the polyester film. It is preferable.
• “Substantially no particles” means, for example, in the case of inorganic particles, when the element derived from the particles is quantitatively analyzed by fluorescent X-ray analysis, 50 ppm or less, preferably 10 ppm or less, most preferably detected The content is below the limit. This means that even if particles are not actively added to the base film, contaminants derived from foreign substances and raw material resin or dirt adhering to the line or equipment in the film manufacturing process will be peeled off and mixed into the film. It is because there is a case to do.
• the base film has a multi-layer structure
• the two-layer / three-layer structure that does not substantially contain inert particles in the inner layer and contains inert particles only in the outermost layer achieves both transparency and workability. It is possible and preferable.
• the thickness of the film is not particularly limited.
• the thickness of the film is preferably 200 ⁇ m or less, and more preferably 100 ⁇ m or less.
• the thickness of the film is preferably 10 ⁇ m or more, more preferably 12 ⁇ m or more, and further preferably 20 ⁇ m or more.
• the polyester film serving as the substrate may be a single layer or a laminate of two or more layers.
• various additives can be contained in a film as needed.
• the additive include an antioxidant, a light resistance agent, an antigelling agent, an organic wetting agent, an antistatic agent, an ultraviolet absorber, and a surfactant.
• an additive according to the function of each layer as needed.
• the polyester film can be obtained by, for example, a method in which the above polyester resin is melt-extruded into a film shape and cooled and solidified with a casting drum to form a film.
• a non-stretched film or a stretched film can be used, but a stretched film is preferable from the viewpoint of durability such as mechanical strength and chemical resistance.
• the stretching method is not particularly limited, and a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse sequential biaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, and the like can be employed.
• the polyester film of the present invention has an acid value of 20 KOHmg / g or less on at least one surface thereof in order to improve the adhesion between the polarizer and a polyvinyl alcohol resin layer such as a water-based adhesive provided on one surface or both surfaces thereof.
• An easy adhesion layer formed from a resin composition containing a certain polyester resin (A), a polyvinyl alcohol resin (B) having a saponification degree of 60 to 85 mol%, and a crosslinking agent (C) is laminated. Yes.
• the easy adhesion layer may be provided on both sides of the polyester film, may be provided only on one side of the polyester film, and a different type of resin coating layer may be provided on the other side.
• the polyester-based resin and the polyvinyl alcohol-based resin form separate domain units in the easy-adhesion layer, and form a phase separation structure generally called a sea-island structure.
• the adhesiveness to the polyester film by the domain constituted by the polyester resin and the adhesiveness to the polyvinyl alcohol resin layer by the domain constituted by the polyvinyl alcohol resin are two. It is considered that the two functions are preferably compatible with each other without being impaired.
• the crosslinking agent (C) is considered to promote and maintain the formation of the domain structure by crosslinking and aggregating the polyvinyl alcohol resin (B).
• polyester resin (A) used in the easy-adhesion layer of the present invention is a copolymer obtained by polycondensation of a dicarboxylic acid component and a diol component, and the dicarboxylic acid component and the diol component are polyesters as the above-mentioned base material. Film materials can be used. From the viewpoint of improving the adhesion to the polyester film substrate, a dicarboxylic acid component having the same or similar structure and properties as the dicarboxylic acid component in the polyester film as the substrate is used as the dicarboxylic acid component of the polyester resin (A). It is preferable to use it.
• an aromatic dicarboxylic acid when employed as the dicarboxylic acid component of the polyester film, it is preferable to use the aromatic dicarboxylic acid as the dicarboxylic acid component of the polyester resin (A).
• aromatic dicarboxylic acid component terephthalic acid and isophthalic acid are most preferred.
• Other aromatic dicarboxylic acids may be added and copolymerized within a range of 10 mol% or less with respect to the total dicarboxylic acid component.
• glycol component of the polyester-based resin (A) it is preferable to use ethylene glycol and branched glycol as constituent components.
• ethylene glycol and branched glycol By having a branched structure, it is considered that it contributes to stress relaxation in the easy-adhesion layer, and it is possible to suitably exhibit adhesion.
• the branched glycol component include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, and 2-methyl-2-butyl-1,3.
• the molar ratio of the branched glycol component is preferably 10 mol%, particularly preferably 20 mol%, based on the total glycol component.
• the upper limit is preferably 80 mol%, more preferably 70 mol%, and particularly preferably 60 mol%. If necessary, diethylene glycol, propylene glycol, butanediol, hexanediol, 1,4-cyclohexanedimethanol or the like may be used in combination.
• the polyester resin (A) used in the present invention is preferably a water-soluble or water-dispersible resin from the viewpoint of compatibility with the polyvinyl alcohol resin (B).
• a compound containing a hydrophilic group such as a sulfonate group or a carboxylate group.
• a dicarboxylic acid component having a sulfonate group is preferable from the viewpoint of imparting hydrophilicity while keeping the acid value of the polyester-based resin (A) low and controlling the reactivity with the crosslinking agent.
• dicarboxylic acid component having a sulfonate group examples include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfonaphthaleneisophthalic acid-2,7-dicarboxylic acid, and 5- (4-sulfophenoxy) isophthalic acid or an alkali thereof.
• metal salt examples include 5-sulfoisophthalic acid.
• the dicarboxylic acid component having a sulfonic acid group is preferably 1 to 15 mol%, more preferably 1.5 to 12 mol%, still more preferably 2 to 10 mol% in the dicarboxylic acid component of the polyester resin (A).
• the dicarboxylic acid component having a sulfonate group is at least the above lower limit, it is suitable for water-solubilization or water-dispersion of the polyester resin. Moreover, when the dicarboxylic acid component which has a sulfonate group is below the said upper limit, it is suitable for adhesiveness with a polyester film base material.
• the polyester resin (A) preferably has fewer carboxylic acid groups which are reactive groups with the crosslinking agent (C).
• the crosslinking agent (C) By reducing the number of carboxyl groups that are reactive with the cross-linking agent, the reactivity with the cross-linking agent is reduced. As a result, the cross-linking polyvinyl alcohol-based resin does not completely mix with the polyvinyl alcohol-based resin. It is considered possible to maintain the domain structure that is formed.
• the acid value of the polyester resin (A) is 20 KOHmg / g or less, preferably 15 KOHmg / g or less, more preferably 10 KOHmg / g or less, further preferably 8 KOHmg / g or less, and still more preferably 5 KOHmg. / G or less.
• the acid value of the polyester resin (A) can be theoretically determined from the result of component analysis by titration method described later or NMR.
• the introduction amount of the carboxylic acid base for water solubilization or water dispersion is reduced, or hydrophilic groups other than the carboxylic acid base are employed.
• lowering the carboxylic acid terminal concentration of the polyester resin it is preferable to employ a polyester resin in which the carboxylic acid terminal group is modified, or a polyester resin having a large number average molecular weight of the polyester resin.
• the number average molecular weight of the polyester resin (A) is preferably 5000 or more, more preferably 6000 or more, and further preferably 10,000 or more.
• the glass transition temperature of the polyester resin (A) is not particularly limited, but is preferably 20 to 90 ° C, and more preferably 30 to 80 ° C. When the glass transition temperature is not less than the above lower limit, it is suitable for blocking resistance, and when the glass transition temperature is not more than the above upper limit, it is suitable for adhesiveness to a polyester film substrate.
• 40 mass% or more and 90 mass% or less are preferable, as for content of the polyester-type resin (A) in an easily bonding layer, 45 mass% or more and 85 mass% or less are more preferable, and 50 mass% or more and 80 mass% or less are more preferable.
• the content of the polyester resin (A) is not less than the above lower limit, it is suitable for adhesion to the polyester film substrate, and if it is not more than the above upper limit, it is with the polyvinyl alcohol resin such as a polarizer and a hydrophilic adhesive. Suitable for adhesiveness.
• the polyvinyl alcohol-based resin is not particularly limited.
• polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; and a saponified product of a copolymer of vinyl acetate and a monomer having copolymerizability; And modified polyvinyl alcohol obtained by converting polyvinyl alcohol into acetalized, urethanized, etherified, grafted, phosphoric acid ester or the like.
• Examples of the monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof; ⁇ -olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkylmalate), disulfonic acid soda alkylmalate, N-methylolacrylamide, acrylamide alkylsulfonic acid alkali salt, N-vinylpyrrolidone, and N-vinylpyrrolidone derivatives. . These polyvinyl alcohol resins may be used alone or in combination of two or more.
• Examples of the polyvinyl alcohol resin (B) used in the present invention include vinyl alcohol-vinyl acetate copolymer, vinyl alcohol-vinyl butyral copolymer, and ethylene-vinyl alcohol copolymer. Among these, vinyl alcohol-vinyl acetate A copolymer and an ethylene-vinyl alcohol copolymer are preferred.
• the polymerization degree of the polyvinyl alcohol-based resin (B) is not particularly limited, but the polymerization degree is preferably 3000 or less from the viewpoint of the coating solution viscosity.
• the copolymerization ratio of vinyl alcohol is represented by the degree of saponification.
• the saponification degree of the polyvinyl alcohol resin (B) of the present invention is preferably 60 mol% or more and 85 mol% or less, more preferably 65 mol% or more and 83 mol% or less, further preferably 68 mol% or more and 80 mol% or less, and 70 More preferably, it is more than mol% and less than 80 mol%, still more preferably 71 mol% or more and 78 mol% or less, and particularly preferably 73 mol% or more and 75 mol% or less.
• the degree of saponification of the polyvinyl alcohol resin (B) is not less than the above lower limit, a crosslinked structure can be more suitably formed with the crosslinking agent (C). Further, when the degree of saponification of the polyvinyl alcohol-based resin (B) is not more than the above upper limit (or less), compatibility with the polyester-based resin (A) can be more suitably achieved.
• the degree of saponification of the vinyl alcohol-based resin can be determined by the amount of alkali consumption required for hydrolysis of copolymer units such as vinyl acetate or the composition analysis by NMR.
• the content of the polyvinyl alcohol resin (B) is preferably 10% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 55% by mass or less, and more preferably 20% by mass or more and 50% by mass or less in the easy-adhesion layer. Further preferred.
• the content of the polyvinyl alcohol resin (B) is not less than the above lower limit, it is suitable for adhesiveness with a polyvinyl alcohol resin layer such as a polarizer and an adhesive, and when the content is not more than the above upper limit, Suitable for adhesiveness.
• the crosslinking agent (C) is not particularly limited as long as it has crosslinkability with a hydroxyl group, and examples thereof include melamine-based, isocyanate-based, carbodiimide-based, oxazoline-based, and epoxy-based compounds. Melamine-based, isocyanate-based, carbodiimide-based, and oxazoline-based compounds are preferable from the viewpoint of the temporal stability of the coating solution.
• the crosslinking agent is preferably a melamine compound or an isocyanate compound that suitably cross-links with the hydroxyl group of the polyvinyl alcohol resin (B).
• a carbodiimide-based cross-linking agent reacts with a carboxyl group
• a melamine-based compound or an isocyanate-based compound reacts with a hydroxyl group
• a polyvinyl alcohol resin (B) having a hydroxyl group as a functional group is more preferably a crosslinked structure.
• an isocyanate type compound from a viewpoint that it forms a crosslinking reaction suitably with the hydroxyl group of polyvinyl alcohol-type resin, and is excellent in transparency.
• you may use a catalyst etc. suitably as needed.
• isocyanate compound a low molecular or high molecular diisocyanate or a trivalent or higher polyisocyanate can be used.
• isocyanate compounds include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 1,5 -Naphthylene diisocyanate, 1,4-naphthylene diisocyanate, phenylene diisocyanate, tetramethylxylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane- 4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4
• aliphatic diisocyanates such as alicyclic diisocyanates, hexamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate, and trimers of these isocyanate compounds.
• an excess amount of these isocyanate compounds and low molecular active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, or polyester polyols, poly Mention may be made of a polymer containing a terminal isocyanate group of a polymer obtained by reacting a polymer active hydrogen compound such as ether polyols and polyamides.
• a melamine compound substituted with a substituent-(CH2) n-O-R (wherein n is an integer of 1 to 3 and R is an alkyl group having 1 to 4 carbon atoms) R in the above formula is preferably methyl.
• the number of the above substituents in one melamine structure is preferably 3-6.
• Specific examples of the melamine compound include Sumitomo Chemical's Sumtex Resin Series M-3, MK, M-6, M-100, MC, etc. and Miwa Chemical Co., Ltd. methylated melamine resin MW-22, MX. -706, MX-042 and the like.
• a blocked isocyanate compound is also preferable. By adding the blocked isocyanate compound, it is possible to more suitably improve the temporal stability of the coating solution.
• the blocked isocyanate compound can be prepared by subjecting the above isocyanate compound and blocking agent to an addition reaction by a conventionally known method.
• the isocyanate blocking agent include phenols such as phenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol; thiophenols such as thiophenol and methylthiophenol; oximes such as acetoxime, methyl etiketooxime, and cyclohexanone oxime.
• Alcohols such as methanol, ethanol, propanol and butanol; halogen-substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol; tertiary alcohols such as t-butanol and t-pentanol ; Lactams such as ⁇ -caprolactam, ⁇ -valerolactam, ⁇ -butyrolactam, ⁇ -propyllactam; aromatic amines; imides; acetylacetone, acetoacetate Active methylene compounds such as malonic acid ethyl ester; mercaptans; imines; ureas; diaryl compounds; and sodium bisulfite and the like.
• a crosslinking agent (C) As content of a crosslinking agent (C), 2 to 50 mass% is preferable in an easily bonding layer, 5 to 40 mass% is more preferable, 8 to 30 mass% is further more preferable. .
• the content of the crosslinking agent (C) is not less than the above lower limit, it is suitable for forming a crosslinked polyvinyl alcohol resin, and when it is not more than the above upper limit, it is suitable for expression of an adhesive effect by the binder resin.
• the blending ratio (A) / (B) of the polyester resin (A) and the polyvinyl alcohol resin (B) is preferably 0.8 to 5, more preferably 1 to 4, more preferably 2 Is more preferably 4 and particularly preferably 2.5 to 3.5.
• (A) / (B) is not less than the above lower limit, it is suitable for adhesiveness with a polyester film substrate, and when it is not more than the above upper limit, it is possible to adhere to a polyvinyl alcohol resin layer such as a polarizer or an adhesive. Is preferred.
• the blending ratio ((A) + (B)) / (C) of the polyester resin (A) and polyvinyl alcohol resin (B) to the crosslinking agent (C) is preferably 2 to 50 in terms of mass ratio. More preferably, it is ⁇ 40, and more preferably 8-30.
• ((A) + (B)) / (C) is not less than the above lower limit, it is suitable for expression of the adhesive effect by the binder resin component, and when it is not more than the above upper limit, it is suitable for the adhesive effect by phase separation. .
• the easy-adhesion layer of the present invention adopts the above composition, and exhibits high adhesiveness equivalent to that of triacetyl cellulose to polarizers and aqueous adhesives, particularly polyvinyl alcohol-based polarizers and aqueous adhesives.
• the remaining area after peeling once is preferably 90% or more, more preferably 95% or more, and further preferably 100% with respect to the water-based adhesive according to the adhesive test described later.
• the remaining area after is preferably 75% or more, more preferably 85% or more, further preferably 95% or more, and the remaining area after 10 continuous peelings is preferably 50% or more, more preferably 80% or more, Preferably it is 90% or more, More preferably, it is 93% or more, Most preferably, it is 95% or more.
• additives such as surfactants, antioxidants, catalysts, heat stabilizers, weathering stabilizers, UV absorbers, organic absorbers, and the like within a range that does not inhibit the effects of the present invention.
• Lubricants, pigments, dyes, organic or inorganic particles, antistatic agents, nucleating agents, and the like may be added.
• the particles contained in the easy-adhesion layer in the present invention include titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay and the like, or a mixture thereof.
• Inorganic particles such as calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, calcium fluoride and other inorganic particles, styrene-based, acrylic-based, melamine-based, benzoguanamine-based, silicone-based Examples include organic polymer particles.
• the average particle size of the sex particles in the easy-adhesion layer is preferably 0.04 to 2.0 ⁇ m, more preferably 0.1 to 1.0 ⁇ m. If the average particle size of the inert particles is less than 0.04 ⁇ m, the formation of irregularities on the film surface becomes insufficient, so that the handling properties such as the slipping property and the winding property of the film are deteriorated and the film is stuck. The workability at the time of alignment may deteriorate. On the other hand, if it exceeds 2.0 ⁇ m, the particles are likely to fall off, which is not preferable.
• the particle concentration in the easy-adhesion layer is preferably 1 to 20% by mass, more preferably 5 to 15% by mass in the solid component.
• the thickness of the easy-adhesion layer can be appropriately set in the range of 0.001 to 2.00 ⁇ m, but in order to achieve both workability and adhesiveness, the thickness is in the range of 0.01 to 1.00 ⁇ m. It is preferably 0.02 to 0.80 ⁇ m, more preferably 0.05 to 0.50 ⁇ m. Adhesiveness becomes inadequate that the thickness of an easily bonding layer is less than 0.01 micrometer. When the thickness of the easy adhesion layer exceeds 2.00 ⁇ m, blocking may occur.
• PET film Polyethylene terephthalate
• the unstretched PET sheet may have a single layer structure or a multilayer structure by a coextrusion method.
• the obtained unstretched PET sheet is subjected to crystal orientation by uniaxial stretching or biaxial stretching.
• the film is stretched 2.5 to 5.0 times in the longitudinal direction with a roll heated to 80 to 120 ° C. to obtain a uniaxially stretched PET film, and then the end of the film is held with a clip Then, it is led to a hot air zone heated to 80 to 180 ° C. and stretched 2.5 to 5.0 times in the width direction.
• uniaxial stretching the film is stretched 2.5 to 5.0 times in the tenter. After stretching, the film is led to a heat treatment zone of 140 to 240 ° C., and heat treatment is performed for 1 to 60 seconds to complete crystal orientation.
• the easy adhesion layer can be provided after the production of the film or in the production process.
• any known method can be used as a method for applying this coating solution to the PET film.
• reverse roll coating method gravure coating method, kiss coating method, die coater method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, curtain coating method, etc. It is done. These methods can be applied alone or in combination.
• the thickness of the easily adhesive layer finally obtained is preferably 0.03 to 0.20 g / m 2 . If it is less than 0.03 g / m ⁇ 2 >, adhesiveness will fall, and if it is thicker than 0.20 g / m ⁇ 2 >, since blocking property and slipperiness will fall, it is unpreferable.
• the polarizing plate of the present invention is a polarizing plate having a polarizer protective film on both sides of a polarizer, and the polarizer protective film on at least one surface is the above-mentioned easily adhesive polyester film for protecting a polarizer.
• the other polarizer protective film may be an easily adhesive polyester film for protecting a polarizer of the present invention, or a film having no birefringence such as a triacetyl cellulose film, an acrylic film, or a norbornene-based film. It is also preferable to use it.
• the polarizer examples include a polyvinyl alcohol film containing a dichroic material such as iodine.
• the polarizer protective film is bonded to the polarizer directly or via an adhesive layer, but it is preferable to bond the polarizer protective film via an adhesive from the viewpoint of improving adhesiveness. In that case, it is preferable to arrange
• a preferable polarizer for bonding the polyester film of the present invention for example, iodine or dichroic material is dyed and adsorbed on a polyvinyl alcohol film, uniaxially stretched in a boric acid aqueous solution, and the stretched state is maintained.
• cleaning and drying is mentioned.
• the stretching ratio of uniaxial stretching is usually about 4 to 8 times.
• Polyvinyl alcohol is suitable as the polyvinyl alcohol film.
• “Kuraray Vinylon” [manufactured by Kuraray Co., Ltd.]
• “Tosero Vinylon” [manufactured by Toh Cello Co., Ltd.]
• “Nichigo Vinylon” [Nippon Synthetic Chemical Co., Ltd.]
• Commercial products such as “made” can be used.
• Examples of the dichroic material include iodine, a disazo compound, and a polymethine dye.
• the adhesive applied to the polarizer is preferably an aqueous one, that is, an adhesive component dissolved in water or dispersed in water.
• a polyvinyl alcohol resin, a urethane resin, or the like is used as a main component, and a composition containing an isocyanate compound, an epoxy compound, or the like can be used as necessary in order to improve adhesiveness.
• the thickness of the adhesive layer is preferably 10 ⁇ m or less, more preferably 5 ⁇ m or less, and even more preferably 3 ⁇ m or less.
• polyvinyl alcohol resin As the main component of the adhesive, in addition to partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, amino group-modified A modified polyvinyl alcohol resin such as polyvinyl alcohol may be used.
• the concentration of the polyvinyl alcohol resin in the adhesive is preferably 1 to 10% by mass, and more preferably 2 to 7% by mass.
• Glass transition temperature In accordance with JIS K7121, a differential scanning calorimeter (manufactured by Seiko Instruments Inc., DSC6200) is used to raise the temperature of a resin sample 10 mg at 20 ° C / min over a temperature range of 25 to 300 ° C. The extrapolated glass transition start temperature obtained from the curve was defined as the glass transition temperature.
• Acid value 1 g (solid content) of a sample was dissolved in 30 ml of chloroform or dimethylformamide, and titrated with 0.1 N potassium hydroxide ethanol solution using phenolphthalein as an indicator to determine the carboxyl groups per gram of the sample. The amount (mg) of KOH required for neutralization was determined.
• Saponification degree Residual acetic acid groups (mol%) of the polyvinyl alcohol resin were quantified using sodium hydroxide according to JIS-K6726, and the value was defined as the saponification degree (mol%). The sample was measured three times, and the average value was defined as the saponification degree (mol%).
• Total light transmittance of polyester film for protecting polarizer The total light transmittance of the polyester film for protecting a polarizer was measured using a turbidimeter (Nippon Denshoku, NDH2000) in accordance with JIS K7105.
• the polyvinyl alcohol resin layer after drying the polyvinyl alcohol aqueous solution (Pura117 made from Kuraray) adjusted to solid content concentration 5 mass% on the surface of the easily adhesive layer of the polyester film for protecting a polarizer is 2 ⁇ m. Then, it was applied with a wire bar and dried at 70 ° C. for 5 minutes.
• As the polyvinyl alcohol aqueous solution a solution in which a red dye was added so as to facilitate the determination was used.
• the prepared evaluation target film was attached to a glass plate having a thickness of 5 mm to which a double-sided tape was attached, and the opposite surface of the evaluation target laminated film on which the polyvinyl alcohol resin layer was formed was attached to the double-sided tape.
• the PVA adhesion rate was 100, and when all the PVA layer was peeled off, the PVA adhesion rate was 0. In addition, what was partially peeled within one square was also included in the number of peeled.
• copolyester resin (A-1) was light yellow and transparent.
• the reduced viscosity of the copolyester resin (A-1) was measured and found to be 0.70 dl / g.
• the glass transition temperature by DSC was 40 ° C.
• copolymer polyester resins (A-2) to (A-5) having different compositions were obtained.
• Table 1 shows the composition (mole% ratio) and other characteristics of these copolyester resins measured by 1 H-NMR.
• polyvinyl alcohol resins (B-2) to (B-7) were used in place of the polyvinyl alcohol resin (B-1) to prepare aqueous solutions, which were designated as (Bw-2) to (Bw-7), respectively.
• Table 2 shows the degree of saponification of the polyvinyl alcohol resins (B-1) to (B-7).
• reaction solution temperature was lowered to 50 ° C., and 47 parts by mass of methyl ethyl ketoxime was added dropwise.
• the infrared spectrum of the reaction solution was measured to confirm that the absorption of isocyanate groups had disappeared, and a block polyisocyanate aqueous dispersion (C-1) having a solid content of 75% by mass was obtained.
• Example 1 Adjustment of coating liquid The following coating agent was mixed and the coating liquid from which the mass ratio of polyester-type resin (A) / polyvinyl alcohol-type resin (B) became 70/30 was created.
• the polyester aqueous dispersion uses an aqueous dispersion (Aw-1) in which a polyester resin having an acid value of 2 KOH mg / g is dispersed, and the polyvinyl alcohol aqueous solution is an aqueous solution in which polyvinyl alcohol having a saponification degree of 74 mol% is dissolved. (Bw-4) was used.
• the unstretched PET sheet was heated to 100 ° C. with a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction with a roll group having a difference in peripheral speed to obtain a uniaxially stretched PET film.
• Example 2 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion was changed to an aqueous dispersion (Aw-2) in which a polyester resin having an acid value of 4 KOHmg / g was dispersed.
• Example 3 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion was changed to an aqueous dispersion (Aw-3) in which a polyester resin having an acid value of 6 KOHmg / g was dispersed.
• Example 4 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution was changed to a polyvinyl alcohol aqueous solution (Bw-3) in which the saponification degree of polyvinyl alcohol was 79 mol%.
• Example 5 A polarizer-protected polyester film was obtained in the same manner as in Example 1, except that the polyvinyl alcohol aqueous solution (Bw-2) had a saponification degree of polyvinyl alcohol of 83 mol%.
• Example 6 Polyester for protecting a polarizer in the same manner as in Example 1, except that the following coating agent was mixed and the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) was changed to 60/40. A film was obtained.
• Block isocyanate-based crosslinking agent (C-1) 0.67% by mass 1.25% by mass of particles (Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
• Catalyst Organic tin compound, solid content concentration 14% by mass
• Example 7 A polyester for protecting a polarizer in the same manner as in Example 1, except that the following coating agent was mixed and the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) was changed to 80/20. A film was obtained. 43.95% by weight of water Isopropanol 30.00% by mass Polyester aqueous dispersion (Aw-1) 13.33% by mass Polyvinyl alcohol aqueous solution (Bw-4) 10.00% by mass Block isocyanate-based crosslinking agent (C-1) 0.67% by mass 1.25% by mass of particles (Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass) Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass Surfactant 0.5% by mass (Silicone, solid content concentration 10% by mass)
• Example 8 A polyester for protecting a polarizer in the same manner as in Example 1 except that the following coating agent was mixed and the mass ratio of polyester resin (A) / polyvinyl alcohol resin (B) was changed to 50/50. A film was obtained.
• Water 33.95% by mass Isopropanol 30.00% by mass Polyester aqueous dispersion (Aw-1) 8.33% by mass Polyvinyl alcohol aqueous solution (Bw-4) 25.00% by mass
• Catalyst Organic tin compound, solid content concentration 14% by mass
• 0.3% by mass Surfactant 0.5% by mass (Silicone, solid content concentration 10% by mass)
• Example 9 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the composition of the coating solution was changed as follows. 40.87% by mass of water Isopropanol 30.00% by mass Polyester water dispersion (Aw-1) 11.67% by mass Polyvinyl alcohol aqueous solution (Bw-4) 15.00% by mass Melamine-based crosslinking agent (C-2) 0.71% by mass (Nicarac MX-042, manufactured by Sanwa Chemical Co., Ltd., solid content 70%) 1.25% by mass of particles (Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass) Surfactant 0.5% by mass (Silicone, solid content concentration 10% by mass)
• Example 10 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the aqueous polyvinyl alcohol solution was changed to an aqueous solution (Bw-5) in which polyvinyl alcohol having a saponification degree of 70 mol% was dissolved. .
• Example 11 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution was changed to an aqueous solution (Bw-6) in which polyvinyl alcohol having a saponification degree of polyvinyl alcohol of 67 mol% was dissolved. .
• Example 12 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the composition of the coating solution was changed as follows. 40.33% by mass of water Isopropanol 30.00% by mass Polyester water dispersion (Aw-1) 11.67% by mass Polyvinyl alcohol aqueous solution (Bw-2) 15.00% by mass Oxazoline-based crosslinking agent (C-3) 1.25% by mass (Epocross WS-500, manufactured by Nippon Shokubai, solid concentration 40% by mass) 1.25% by mass of particles (Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass) Surfactant 0.5% by mass (Silicone, solid content concentration 10% by mass)
• Example 13 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion was changed to an aqueous dispersion (Aw-5) in which a polyester resin having an acid value of 10 KOHmg / g was dispersed.
• Comparative Example 1 Polyester for protecting a polarizer in the same manner as in Example 1, except that the following coating agent was mixed and the mass ratio of polyester resin (A) / polyvinyl alcohol resin (B) was changed to 100/0. A film was obtained.
• Block isocyanate-based crosslinking agent (C-1) 0.67% by mass 1.25% by mass of particles (Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
• Catalyst Organic tin compound, solid content concentration 14% by mass
• 0.3% by mass Surfactant 0.5% by mass (Silicone, solid content concentration 10% by mass)
• Comparative Example 2 A polyester for protecting a polarizer in the same manner as in Example 1 except that the following coating agent was mixed and the mass ratio of polyester resin (A) / polyvinyl alcohol resin (B) was changed to 0/100. A film was obtained. 17.28% by mass of water Isopropanol 30.00% by mass Polyvinyl alcohol aqueous solution (Bw-4) 50.00% by mass Block isocyanate-based crosslinking agent (C-1) 0.67% by mass 1.25% by mass of particles (Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass) Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass Surfactant 0.5% by mass (Silicone, solid content concentration 10% by mass)
• Comparative Example 3 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion was changed to an aqueous dispersion (Aw-4) in which a polyester resin having an acid value of 25 KOH mg / g was dispersed.
• Comparative Example 4 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution was changed to an aqueous solution (Bw-1) in which polyvinyl alcohol having a saponification degree of 88 mol% was dissolved.
• Comparative Example 5 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution was changed to an aqueous solution (Bw-7) in which polyvinyl alcohol having a saponification degree of 40 mol% was dissolved.
• Comparative Example 6 A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the following coating agent was mixed and the crosslinking agent was not mixed. 41.58% by mass of water Isopropanol 30.00% by mass Polyester water dispersion (Aw-1) 11.67% by mass Polyvinyl alcohol aqueous solution (Bw-4) 15.00% by mass 1.25% by mass of particles (Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass) Surfactant 0.5% by mass (Silicone, solid content concentration 10% by mass)
• Reference example 1 The result of having performed the said adhesive test using the TAC film (The Fuji Film Co., Ltd. product, thickness 80micrometer, saponification-processed) is shown as a film for polarizer protection.
• the easy-adhesive polyester film for protecting a polarizer of the present invention has high adhesiveness with a polarizer / water-based adhesive. Therefore, it can be suitably used as a polarizer protective member.

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