CN114573853A - Polyester film and preparation method thereof - Google Patents

Polyester film and preparation method thereof Download PDF

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Publication number
CN114573853A
CN114573853A CN202111576765.6A CN202111576765A CN114573853A CN 114573853 A CN114573853 A CN 114573853A CN 202111576765 A CN202111576765 A CN 202111576765A CN 114573853 A CN114573853 A CN 114573853A
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China
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polyester film
polyester
film
temperature
crosslinking agent
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CN202111576765.6A
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Chinese (zh)
Inventor
孙月
牛运峰
程新星
姚晔
郑云霞
祁晓然
李�瑞
刘洋
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Hefei Lucky Science and Technology Industry Co Ltd
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Hefei Lucky Science and Technology Industry Co Ltd
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Priority to CN202111576765.6A priority Critical patent/CN114573853A/en
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    • 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
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/043—Improving the adhesiveness of the coatings per se, e.g. forming primers
    • 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
    • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
    • 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
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/0427—Coating with only one layer of a composition containing a polymer binder
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • 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
    • C09D5/002—Priming paints
    • 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
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/63—Additives non-macromolecular organic
    • 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
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/65—Additives macromolecular
    • 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
    • B32B2255/00—Coating on the layer surface
    • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
    • 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
    • B32B2255/00—Coating on the layer surface
    • B32B2255/26—Polymeric coating
    • 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
    • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • 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
    • C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers

Abstract

The invention belongs to the technical field of polyester films, and relates to a polyester film and a preparation method thereof, wherein the polyester film comprises a base film and a primer coating coated on at least one surface of the base film; the base coat comprises the following substances in parts by weight: 20-65 parts of polyester, 30-50 parts of polyurethane and a crosslinking agent5-30 parts; the cross-linking agent comprises a cross-linking agent A, a cross-linking agent B and a cross-linking agent C in any weight ratio, wherein the cross-linking temperature of the cross-linking agent A is as follows: t isA<80 ℃; the crosslinking temperature of the crosslinking agent B is as follows: t is not less than 80 DEG CBNot more than 120 ℃; crosslinking temperature of the crosslinking agent C: t isCMore than 120 ℃. The polyester film can effectively inhibit the precipitation of surface oligomers, and has good adhesive force on a hard coating, an adhesive layer and a release layer.

Description

Polyester film and preparation method thereof
Technical Field
The invention belongs to the technical field of polyester films, and relates to a polyester film and a preparation method thereof.
Background
Because the polyester film has good dimensional stability, chemical resistance, high transparency and good processability compared with other plastic films, the polyester film is widely applied to the deep processing of polyester film materials for various functional films, such as functional film materials of transparent conductive films, high-temperature resistant protective films, polarizer release films and the like. The high-temperature-resistant IMD film has good thermal stability, printability, impact resistance, scratch resistance and chemical stability, and is applied to the field of high-grade IMD in-film decoration processing.
For the applications, the functional layers such as a hard coating layer, an adhesive layer, a release layer and the like need to be reprocessed on the surface of the polyester film, and the polyester film is subjected to oven heat treatment in the reprocessing process; in the application process of various functional film materials, high-temperature or high-temperature and high-humidity treatment can be carried out for a long time, and both the processes can cause the formation of oligomers in the polyester film and the migration and precipitation of the oligomers to the surface of the film, so that the white fog of the functional film materials or the color difference of decorative devices can be caused. After the oligomer is precipitated on the surface of the film, the film roll is polluted by the oligomer in the unwinding and winding processes, and the optical and application characteristics of the final product are deteriorated. In order to prevent the migration of oligomers in the polyester film, the oligomer content is reduced during the polymerization of the polyester film, but oligomers are generated and migrate to the surface under high temperature or high temperature and high humidity conditions.
Therefore, how to effectively solve the problem of oligomer precipitation of the polyester film, especially how to keep the low surface precipitation of the film during long-time high-temperature treatment, and meanwhile, how to have good adhesion to the hard coating layer, the adhesive layer and the release layer is a problem of great interest in the industry.
Disclosure of Invention
The invention aims to provide a polyester film and a preparation method thereof, which can effectively inhibit the precipitation of surface oligomers, particularly keep low surface precipitation of the film during long-time high-temperature treatment, and have good adhesive force to a hard coating, an adhesive layer and a release layer.
In order to solve the technical problems, the invention adopts the following technical scheme: a polyester film comprises a base film and a primer coating coated on at least one surface of the base film; the base coat comprises the following substances in parts by weight:
20 to 65 portions of polyester
30-50 parts of polyurethane
5-30 parts of a cross-linking agent;
the cross-linking agent comprises a cross-linking agent A, a cross-linking agent B and a cross-linking agent C in any weight ratio, wherein the cross-linking temperature of the cross-linking agent A is as follows: t isA<80 ℃; the crosslinking temperature of the crosslinking agent B is as follows: t is not less than 80 DEG CBNot more than 120 ℃; crosslinking temperature of the crosslinking agent C: t isC﹥120℃。
As an improved technical scheme of the application, after the polyester film is subjected to heat treatment at 80 ℃ for 250 hours, the precipitation amount of oligomer on the surface of a bottom coating is 3.0 x 10－4mg/cm2The following.
As a modified mode of the present application, the polyester is a naphthalenedicarboxylic acid polyester.
As an improved technical solution of the present application, the polyurethane is a polycarbonate-based polyurethane.
As an improved technical scheme of the application, the base coating is coated after the base film is longitudinally stretched and before the base film is transversely stretched.
In a further embodiment of the present invention, the film is coated with a primer layer, held by a gripper and introduced into a preheating zone stretched in the transverse direction, the temperature of the preheating zone being 120 ℃ or lower.
As a technical scheme of improvement of the application, the preheating zone comprises at least two sections, and the temperature of the first section of the preheating zone is less than 100 ℃.
As an improved technical scheme of the application, the temperature of the transverse stretching area is more than 120 ℃.
As an improved technical scheme of the application, the cross-linking agent A is one of aziridine and a carbodiimide cross-linking agent or two of the aziridine and the carbodiimide cross-linking agent in any weight ratio,
as an improved technical scheme of the application, the crosslinking agent B is one or two of oxazoline and blocked isocyanate crosslinking agent in any weight ratio.
As an improved technical scheme of the application, the crosslinking agent C is one of melamine and epoxy crosslinking agent or two of the melamine and the epoxy crosslinking agent in any weight ratio.
As a technical proposal for improvement of the application, the ratio of the cross-linking agent A, B, C is 1:1: 2.
It is another object of the present application to provide a method for preparing an optical polyester film, comprising the steps of:
a. sending the raw material of the base film into a corresponding extrusion system for melt extrusion, wherein the melt extrusion temperature is 260-285 ℃;
b. forming the melt of the base film into an unoriented cast thick sheet on a rotating cooling roller through a die head;
c. preheating the cooled casting thick sheet and longitudinally stretching the casting thick sheet by 3.0-3.8 times;
d. coating the primer coating liquid on one surface or two surfaces of the longitudinally stretched membrane;
e. the diaphragm coated with the base coat is held by a clamp and guided into a transverse stretching preheating zone, and after preheating and drying at 80-120 ℃, the diaphragm is transversely stretched by 2.5-4.5 times at 121-160 ℃;
f. and (3) performing heat setting on the stretched film at the heat setting temperature of 160-235 ℃, cooling and rolling to obtain the optical polyester film.
Compared with the prior art, the invention has the following advantages;
1. the polyester film of the invention has a primer layer containing polyester, polyurethane and a crosslinking agent A, B, C, and is applied after longitudinal stretching and before transverse stretching of a base film. In the preheating and transverse stretching processes of the film, the polyester and polyurethane in the coating liquid and the first section of the preheating zone of the crosslinking agent A can perform preliminary crosslinking reaction. As the temperature of the preheating zone rises, the water in the coating liquid is evaporated, the polyester and the polyurethane in the base coat and the cross-linking agent approach each other, and the cross-linking agent B can perform further cross-linking reaction with the polyester and the polyurethane. When the film is transversely stretched, the transverse stretching is carried out after the moisture of the base coat is completely evaporated along with the increase of the temperature of a stretching area. Since transverse stretching generally reduces the crosslink density of the primer layer, the polyester, polyurethane and crosslinker C of the present invention can continue the crosslinking reaction in the stretched zone, reducing the adverse effect of stretching on the crosslinking of the primer layer. The bottom coating of the invention is subjected to three stages of preheating, drying and stretching in a preheating and stretching area of the polyester film, and is subjected to sufficient crosslinking reaction by the crosslinking agents with different crosslinking temperatures, and the polyester and the polyurethane in the bottom coating form a compact interpenetrating network structure through the crosslinking of the crosslinking agents, so that the precipitation of oligomers on the surface of the base film can be effectively inhibited. In the subsequent processing and using process, even in a high-temperature or high-temperature and high-humidity environment for a long time, the low precipitation amount of the surface oligomer can be kept, so that the using effect of the polyester film is not influenced.
2. The polyester film of the present invention has a base coat layer containing a naphthalenedicarboxylic acid polyester, a polycarbonate polyurethane and a crosslinking agent A, B, C in a ratio of 1:1: 2. The naphthalenedicarboxylic acid polyester can block the oligomer in the film, does not migrate to the surface of the film, and has good adhesion to various cured layers, adhesive layers and release layers through a primer layer formed with polycarbonate polyurethane and a crosslinking agent.
3. The polyester film has the characteristics of low precipitation and high adhesion, and is suitable for the fields of high-end film materials such as hardened films, polarizer protective films, polarizer release films and the like in display devices.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.
The base film is preferably a plastic film, and may be a polymer film. Polyester film, polyethylene terephthalate (PET), polycarbonate film (PC), polymethyl methacrylate film (PMMA), composite film of ABS (acrylonitrile-butadiene-styrene) and PET, composite film of PET and PEN (polyethylene naphthalate), composite film of PC and PMMA, polypropylene terephthalate, polybutylene terephthalate, polyethylene 2, 6-naphthalate, syndiotactic styrene, norbornene polymer, polycarbonate, polyarylate, and the like can be used.
The above-mentioned base film (plastic film) may be a single layer structure, a two-layer structure, or a multilayer structure of three or more layers. The interlayer structure can be a/b, a/b/a, a/b/c, a/b/c/a, a/b/c/b/a and the like, and preferably is a/b/a three-layer structure. The thickness of the base film used in the present invention is not particularly limited, and may be arbitrarily selected in the range of 12 to 380 μm according to the specification of the use application.
The invention coats a base coat on at least one surface of a biaxial stretching basal membrane, the base coat comprises polyester, polyurethane and a cross-linking agent A, a cross-linking agent B and a cross-linking agent C, the reaction temperature of the cross-linking agent A is as follows: t isA<80 ℃, crosslinking temperature of crosslinking agent B: t is not less than 80 DEG CBAt most 120 ℃, the crosslinking temperature of the crosslinking agent C is as follows: t isCTg is higher than 120 ℃, the base coating is coated after longitudinal stretching and before transverse stretching of the base film, the film is held by a clamp after the base coating is coated and is led into a transverse stretching preheating zone, the preheating zone at least comprises two sections, the temperature of the preheating zone is lower than or equal to 120 ℃, and the first section of the preheating zoneIs less than 100 ℃; the temperature of the transverse stretching zone is greater than 120 ℃.
During the preheating and transverse stretching of the film, the polyester and polyurethane in the coating liquid and the crosslinking agent A in the preheating zone can have primary crosslinking reaction in the first section. As the temperature of the preheating zone rises, the water in the coating liquid evaporates, the polyester and the polyurethane in the base coat and the cross-linking agent approach each other, and the cross-linking agent B can perform further cross-linking reaction with the polyester and the polyurethane. When the film is transversely stretched, the transverse stretching is carried out after the moisture of the base coat is completely evaporated along with the increase of the temperature of a stretching area. Since transverse stretching generally reduces the crosslink density of the primer layer, the aqueous resin and crosslinker C of the present invention can continue the crosslinking reaction in the stretched zone, reducing the adverse effect of stretching on the crosslinking of the primer layer. The bottom coating of the invention is subjected to three stages of preheating, drying and stretching in a preheating and stretching area of the polyester film, and is subjected to sufficient crosslinking reaction by the crosslinking agents with different crosslinking temperatures, and the polyester and the polyurethane in the bottom coating form a compact interpenetrating network structure through the crosslinking of the crosslinking agents, so that the precipitation of oligomers on the surface of the base film can be effectively inhibited. In the subsequent processing and using process, even in a high-temperature or high-temperature and high-humidity environment for a long time, the low precipitation amount of the surface oligomer can be kept, so that the using effect of the polyester film is not influenced.
According to the polyester film, a base coat comprises the following substances in parts by weight:
32 to 65 portions of polyester
30-50 parts of polyurethane
5-30 parts of a cross-linking agent;
the polyester is a naphthalenedicarboxylic acid-based polyester, the polyurethane is a polycarbonate-based polyurethane, and the naphthalenedicarboxylic acid-based polyester has a naphthalene ring structure, so that the oligomer can be confined in the film and does not migrate and precipitate to the surface of the film. But the adhesion of the naphthalenedicarboxylic acid polyester to the functional layer of the subsequent processing is insufficient, the naphthalenedicarboxylic acid polyester of the present invention has good adhesion to various hard coatings, adhesive layers and release layers through the primer layer formed by the naphthalenedicarboxylic acid polyester, polycarbonate-based polyurethane and a crosslinking agent, and the adhesion is excellent after the high temperature and high humidity treatment. The naphthalenedicarboxylic acid based polyester is obtained by polycondensation of a naphthalenedicarboxylic acid with a diol, such as 1, 4-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid with an aliphatic dibasic acid or an aromatic dibasic acid. The polycarbonate polyurethane is obtained by polymerizing an aliphatic polycarbonate polyol and a polyisocyanate.
In the invention, the cross-linking agent accounts for 5-30 parts of the weight of the base coat, and the cross-linking agent A, the cross-linking agent B and the cross-linking agent C can adopt any weight ratio, and the preferable ratio is 1:1: 2. Crosslinking temperature of crosslinking agent a: t isA<A is one or two of aziridine and carbodiimide crosslinking agents at 80 ℃; crosslinking temperature of crosslinking agent B: 100<TBB is one or two of oxazoline and blocked isocyanate crosslinking agent at the temperature of less than or equal to 120 ℃; crosslinking temperature of crosslinking agent C: t isCTg is more than 120 ℃, and C is one or two of melamine and epoxy crosslinking agents. The crosslinking agent may be a known water-dispersible or water-soluble crosslinking agent, and is preferably a crosslinking agent having good compatibility with an aqueous resin and good transparency.
Wherein the aziridine-based crosslinking agent may be selected from compounds containing an aziridine structure. The carbodiimide-based crosslinking agent may be selected from compounds having a carbodiimide structure. The oxazoline-based cross-linking agent may be selected from compounds containing oxazoline structures, such as oxazoline-based acrylates, which are copolymers of acrylic monomers and oxazoline-based monomers. The isocyanate crosslinking agent can be selected from compounds containing isocyanate structures, and because isocyanate groups are easy to react with water, the isocyanate in the invention is a blocked isocyanate crosslinking agent, the deblocking temperature is 100-120 ℃, and the crosslinking reaction is carried out in the drying stage of the coating liquid, thereby being beneficial to improving the adhesion of the base coat and ensuring the effective period of the coating liquid. The melamine-based crosslinking agent may be selected from compounds having a melamine structure. The epoxy crosslinking agent may be selected from compounds having an epoxy structure.
The polyester film of the present invention, after heat treatment at 80 ℃ for 250 hours, had an oligomer precipitation amount on the surface of the primer layer of 3.0X 10－4mg/cm2The content is preferably 2.0X 10－4mg/cm2The following. Guarantee lightIn the subsequent use process of the chemical polyester film, the chemical polyester film is not polluted by oligomer even in a high-temperature or high-temperature and high-humidity environment for a long time, and the application characteristics such as the optical performance of a final product are not influenced.
The haze of the polyester film of the present invention is less than 5.0%, preferably less than 3.0%. The total light transmittance is greater than 89%, preferably greater than 90%.
The solid content of the coating liquid of the present invention can be controlled in the range of 2.0% to 20%, and the coating amount can be selected in the range of 2g/m2～15g/m2And (3) a range.
To the undercoat layer coating liquid, a cosolvent, a wetting agent, a pH adjuster, a catalyst, a surfactant, an antistatic agent, and the like may be added as necessary.
The method of applying the base coat layer on at least one side of the base film may employ one or more of known coating methods such as gravure coating, bar coating, spray coating, air knife coating, dip coating, etc.; the polyester film after biaxial stretching may be coated with an undercoat layer (on-line coating), or may be coated with a non-stretched polyester film or uniaxially stretched and then subjected to biaxial stretching (in-line coating); the latter in-line coating process is preferred in the present invention.
The present invention may be selected from processing techniques known in the art such as tube film processes, flat film processes, preferably flat film processes, and the molten polyester melt is coextruded from a T die onto a chilled roll to ensure that the polyester is chilled to an amorphous state and then stretch oriented to provide a polymer film. The stretching of the polymer film may be either monoaxially or biaxially oriented, but it is preferred that the polymer film is biaxially oriented in two mutually perpendicular directions in the plane to obtain excellent mechanical and physical properties.
The method for producing the optical polyester film of the present invention preferably comprises the steps of:
1. sending the raw material of the base film into a corresponding extrusion system for melt extrusion, wherein the melt extrusion temperature is 260-285 ℃;
2. forming the melt of the base film into an unoriented cast thick sheet on a rotating cooling roller through a die head;
3. preheating the cooled casting thick sheet and longitudinally stretching the casting thick sheet by 3.0-3.8 times;
4. coating the primer coating liquid on one surface or two surfaces of the longitudinally stretched membrane;
5. the diaphragm coated with the base coat is held by a clamp and guided into a transverse stretching preheating zone, and after preheating and drying at 80-120 ℃, the diaphragm is transversely stretched by 2.5-4.5 times at 121-160 ℃;
6. and (3) performing heat setting on the stretched film at the heat setting temperature of 160-235 ℃, cooling and rolling to obtain the optical polyester film.
The polyester film of the present invention is further illustrated by the following specific examples, but the scope of the present invention is not limited to these examples.
Example 1
Preparation of undercoat coating liquid (1)
Figure BDA0003425466150000071
0.10g of aziridine CX-100 (solid content: 100%, Kyoho, Guangzhou), 0.10g of isocyanate Ultra 3100 (solid content: 100%, COVESTRO), 0.29g of melamine resin PM-80 (solid content: 70%, DIC), 26.00g of naphthalene-containing polyester Z-592 (solid content: 20%, GOO Chemical), and 6.86g of polycarbonate-based polyurethane
Figure BDA0003425466150000073
DL 2077 (35% solids, COVESTRO) and 66.65g deionized water were dispersed uniformly by a high shear emulsifier to give a primer coating solution with a solids content of 8%.
Preparation of optical polyester film
Taking polyethylene terephthalate polyester chips as a core layer, uniformly mixing the polyethylene terephthalate polyester chips with 2.0 mu m silicon dioxide master batch chips to obtain a surface layer, wherein the 2.0 mu m silicon dioxide accounts for 50ppm of the total polyethylene terephthalate polyester chips, and melting, mixing and extruding the two materials at 275 ℃; casting the melt into a casting sheet roller to be cooled into an unoriented casting thick sheet, and then performing longitudinal stretching at a longitudinal stretching ratio of 3.5 times; then coating the prepared primer coating liquid on one surface of the longitudinal stretching sheet; the film coated with the primer was introduced into a transverse stretching preheating zone by holding with a clip, preheated at 90 ℃/110 ℃ in two preheating zones, transversely stretched 4.2-fold in three stretching zones at 121 ℃/128 ℃/135 ℃ and heat-set at 235 ℃ for winding to obtain a 75 μm thick polyester film, and the properties thereof were measured (see Table 2).
Example 2
The base coat coating liquid (1) in example 1 was changed to a base coat coating liquid (2), and the base coat coated film sheet was treated at the preheating and stretching temperatures in table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see table 2).
Figure BDA0003425466150000072
Figure BDA0003425466150000081
Example 3
The undercoat layer coating liquid (1) in example 1 was changed to the undercoat layer coating liquid (3), and the undercoat film sheet was treated at the preheating and stretching temperatures in Table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see Table 2).
Preparation of undercoat layer coating liquid (3)
Figure BDA0003425466150000082
Example 4
The undercoat layer coating liquid (1) in example 1 was changed to the undercoat layer coating liquid (4), and the undercoat film sheet was treated at the preheating and stretching temperatures in Table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see Table 2).
Preparation of undercoat layer coating liquid (4)
Figure BDA0003425466150000083
Example 5
The undercoat layer coating liquid (1) in example 1 was changed to the undercoat layer coating liquid (5), and the undercoat film sheet was treated at the preheating and stretching temperatures in Table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see Table 2).
Preparation of undercoat layer coating liquid (5)
Figure BDA0003425466150000091
Comparative example 1
The undercoat layer coating liquid (1) in example 1 was changed to the undercoat layer coating liquid (6), and the undercoat film sheet was treated at the preheating and stretching temperatures in Table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see Table 2).
Preparation of undercoat-coating liquid (6)
Figure BDA0003425466150000092
Comparative example 2
The base coat coating liquid (1) in example 1 was changed to a base coat coating liquid (7), and the base coat coated film sheet was treated at the preheating and stretching temperatures in table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see table 2).
Preparation of undercoat layer coating liquid (7)
Figure BDA0003425466150000101
Comparative example 3
The undercoat layer coating liquid (1) in example 1 was changed to the undercoat layer coating liquid (8), and the undercoat film sheet was treated at the preheating and stretching temperatures in Table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see Table 2).
Preparation of undercoat coating liquid (8)
Figure BDA0003425466150000102
Comparative example 4
The undercoat layer coating liquid (1) in example 1 was changed to the undercoat layer coating liquid (9), and the undercoat film sheet was treated at the preheating and stretching temperatures in Table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see Table 2).
Preparation of undercoat coating liquid (9)
Figure BDA0003425466150000103
Figure BDA0003425466150000111
Comparative example 5
The base coat coating liquid (1) in example 1 was changed to a base coat coating liquid (10), and the base coat coated film sheet was treated at the preheating and stretching temperatures in table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see table 2).
Preparation of undercoat coating liquid (10)
Figure BDA0003425466150000112
Comparative example 6
The base coat coating liquid (1) in example 1 was changed to a base coat coating liquid (11), and the base coat coated film sheet was treated at the preheating and stretching temperatures in table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see table 2).
Preparation of undercoat layer coating liquid (11)
Figure BDA0003425466150000113
Comparative example 7
The undercoat layer coating liquid (1) in example 1 was changed to the undercoat layer coating liquid (12), and the undercoat film sheet was treated at the preheating and stretching temperatures in Table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see Table 2).
Preparation of undercoat coating liquid (12)
Figure BDA0003425466150000121
Comparative example 8
The undercoat layer coating liquid (1) in example 1 was changed to the undercoat layer coating liquid (3), and the undercoat film sheet was treated at the preheating and stretching temperatures in Table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see Table 2).
Comparative example 9
The undercoat layer coating liquid (1) in example 1 was changed to the undercoat layer coating liquid (3), and the undercoat film sheet was treated at the preheating and stretching temperatures in Table 1 in the same manner as in example 1 to obtain a polyester film, and the properties thereof were measured (see Table 2).
Specific implementations of the polyester film include the following example 1:
TABLE 1 parts by weight of components of the base coat, preheating zone and stretching zone temperatures
Figure BDA0003425466150000122
Figure BDA0003425466150000131
The polyester films provided in the examples of the present invention and the comparative examples were tested for their main properties in the following manner.
1. Haze degree
Measured according to the method specified in GB/T25273.
2. Light transmittance
Measured according to the method specified in GB/T2410.
3. Oligomer precipitation amount on the surface of the primer layer:
the polyester films of examples and comparative examples were placed in an oven and heat-treated at 80 ℃ for 250 hours, and then the oligomer precipitated on the surface of the undercoat layer was dissolved in tetrahydrofuran, and the content of the oligomer was measured by high performance liquid chromatography.
4. Adhesion test of primer and hard coat
From the polyester films obtained in examples and comparative examples, a UV-curable hard coat layer was applied on the undercoat layer and cured to obtain a polyester functional film.
Testing the initial adhesion: the adhesion of the hardened layer was tested with a hundred grid knife, according to standard GBT9286-1998, which was rated 6 from high to low on a scale of 0, 1, 2, 3, 4 and 5.
Testing high-temperature and high-humidity resistance adhesive force: the polyester functional film is placed in a constant temperature and humidity box and is placed for 500 hours under the conditions that the temperature is 65 ℃ and the relative humidity is 95 percent. Then, the polyester functional film was taken out and left to stand at room temperature under normal humidity for 12 hours. With reference to standard GBT9286-1998, the hard coat side adhesion of polyester functional films was tested with a penny knife, with a total of 6 ratings from high to low of 0, 1, 2, 3, 4 and 5.
5. Adhesion test of primer and adhesive layers
From the polyester films obtained in examples and comparative examples, a thermosetting adhesive layer was coated on the primer layer and cured to obtain a polyester functional film.
Testing the initial adhesion: the adhesion of the adhesive layer was tested with a hundred grid knife, according to standard GBT9286-1998, and was rated 6 from high to low on a scale of 0, 1, 2, 3, 4 and 5.
Testing high-temperature and high-humidity resistance adhesive force: the polyester functional film is placed in a constant temperature and humidity box and is placed for 500 hours under the conditions that the temperature is 65 ℃ and the relative humidity is 95 percent. Then, the polyester functional film was taken out and left to stand at room temperature under normal humidity for 12 hours. With reference to standard GBT9286-1998, the adhesion of the polyester functional film on the adhesive side was tested with a penny knife, which was rated 6 from high to low on a scale of 0, 1, 2, 3, 4 and 5.
Table 2 results of performance test of the polyester film and the polyester functional film in each of examples and comparative examples:
Figure BDA0003425466150000141
as demonstrated in examples 1-5 in Table 2, the optical polyester film obtained by the technical scheme of the invention can effectively inhibit the precipitation of surface oligomers, particularly keep low surface precipitation during long-time high-temperature treatment, and simultaneously has good adhesion. Further, as shown in comparative example 1, it was confirmed that when the polycarbonate-based polyurethane was not contained in the undercoat layer, the film could keep the surface deposition low, but the adhesion was remarkably decreased. As shown in comparative examples 2 to 9, it was confirmed that when the composition of matter, the weight percentage or the crosslinker component in the undercoat layer was changed, the undercoat layer could not effectively suppress the precipitation of surface oligomers, and the adhesion was decreased. As shown in comparative examples 8 and 9, it was confirmed that the effect of the undercoat layer to suppress surface oligomers and the adhesion were reduced when the temperatures of the transverse drawing preheating zone and the stretching zone were changed.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

Claims (13)

1. The polyester film is characterized by comprising a base film and a primer coating coated on at least one surface of the base film; the base coat comprises the following substances in parts by weight:
20 to 65 portions of polyester
30-50 parts of polyurethane
5-30 parts of a cross-linking agent;
the cross-linking agent comprises any weight ratioCrosslinking agent A, crosslinking agent B and crosslinking agent C, wherein the crosslinking temperature of the crosslinking agent A is as follows: t isA<80 ℃; the crosslinking temperature of the crosslinking agent B is as follows: t is not less than 80 DEG CBNot more than 120 ℃; crosslinking temperature of the crosslinking agent C: t isC﹥120℃。
2. The polyester film according to claim 1, wherein the oligomer precipitation amount on the surface of the primer layer after the polyester film is heat-treated at 80 ℃ for 250 hours is 3.0X 10－4mg/cm2The following.
3. The polyester film according to claim 1, wherein the polyester is a naphthalenedicarboxylic acid polyester.
4. The polyester film according to claim 1, wherein the polyurethane is a polycarbonate-based polyurethane.
5. The polyester film according to claim 1, wherein the primer layer is applied after the base film is longitudinally stretched and before the base film is transversely stretched.
6. The polyester film according to claim 1, wherein after the film is coated with a primer layer, the film is held by a gripper and introduced into a transverse stretching preheating zone having a temperature of 120 ℃ or lower
7. The polyester film of claim 6, wherein said preheating zone comprises at least two sections, and wherein the temperature of the first section of said preheating zone is less than 100 ℃.
8. The polyester film of claim 6, wherein the temperature of said transverse stretching zone is greater than 120 ℃.
9. The polyester film according to claim 1, wherein the crosslinking agent A is one or two of aziridine and carbodiimide crosslinking agents in any weight ratio.
10. The polyester film according to claim 1, wherein the crosslinking agent B is one or two of oxazoline and blocked isocyanate crosslinking agent in any weight ratio.
11. The polyester film according to claim 1, wherein the crosslinking agent C is one or two of melamine and epoxy crosslinking agent at any weight ratio.
12. The polyester film according to claim 1, wherein the ratio of the crosslinking agent A, B, C is 1:1: 2.
13. A process for preparing a polyester film according to any of claims 1 to 12, comprising the steps of:
a. sending the raw material of the base film into a corresponding extrusion system for melt extrusion, wherein the melt extrusion temperature is 260-285 ℃;
b. forming the melt of the base film into an unoriented cast thick sheet on a rotating cooling roller through a die head;
c. preheating the cooled casting thick sheet and longitudinally stretching the casting thick sheet by 3.0-3.8 times;
d. coating the primer coating liquid on one surface or two surfaces of the longitudinally stretched membrane;
e. the diaphragm coated with the base coat is held by a clamp and guided into a transverse stretching preheating zone, and after preheating and drying at 80-120 ℃, the diaphragm is transversely stretched by 2.5-4.5 times at 121-160 ℃;
f. and (3) performing heat setting on the stretched film at the heat setting temperature of 160-235 ℃, cooling and rolling to obtain the optical polyester film.
CN202111576765.6A 2021-12-22 2021-12-22 Polyester film and preparation method thereof Pending CN114573853A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101866023A (en) * 2010-05-28 2010-10-20 中国乐凯胶片集团公司 Optical polyester film and preparation method thereof
CN102905899A (en) * 2010-05-29 2013-01-30 三菱树脂株式会社 Layered polyester film
CN102905898A (en) * 2010-05-29 2013-01-30 三菱树脂株式会社 Layered polyester film
CN105377968A (en) * 2013-07-16 2016-03-02 三菱树脂株式会社 Coated film
CN111073015A (en) * 2019-12-29 2020-04-28 合肥乐凯科技产业有限公司 Optical film

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101866023A (en) * 2010-05-28 2010-10-20 中国乐凯胶片集团公司 Optical polyester film and preparation method thereof
CN102905899A (en) * 2010-05-29 2013-01-30 三菱树脂株式会社 Layered polyester film
CN102905898A (en) * 2010-05-29 2013-01-30 三菱树脂株式会社 Layered polyester film
CN105377968A (en) * 2013-07-16 2016-03-02 三菱树脂株式会社 Coated film
CN111073015A (en) * 2019-12-29 2020-04-28 合肥乐凯科技产业有限公司 Optical film

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