CN110920166B - Preparation method of double-layer polyester film and film-coated metal plate - Google Patents

Preparation method of double-layer polyester film and film-coated metal plate Download PDF

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Publication number
CN110920166B
CN110920166B CN201811090577.0A CN201811090577A CN110920166B CN 110920166 B CN110920166 B CN 110920166B CN 201811090577 A CN201811090577 A CN 201811090577A CN 110920166 B CN110920166 B CN 110920166B
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polyester film
copolyester
double
film
layer
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CN110920166A (en
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谢龙
陈红星
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Baoshan Iron and Steel Co Ltd
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Baoshan Iron and Steel Co Ltd
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    • 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
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B32B15/09—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising polyesters
    • 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
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/18—Layered products comprising a layer of metal comprising iron or steel
    • 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
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • 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
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D65/38—Packaging materials of special type or form
    • B65D65/40—Applications of laminates for particular packaging purposes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
    • C08G63/16—Dicarboxylic acids and dihydroxy compounds
    • C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
    • C08G63/181—Acids containing aromatic rings
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/78—Preparation processes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • 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 discloses a preparation method of a double-layer polyester film, which comprises the following steps: s1: preparation of modified copolyester: carrying out copolymerization reaction on isophthalic acid, 1, 4-cyclohexanedimethanol and neopentyl glycol to obtain modified copolyester; in the copolymerization reaction, SiO is added in an in-situ polymerization mode2To obtain SiO with the mass fraction of 1200ppm2The copolyester resin of (a); s2: preparation of a homogeneous mixture of copolyester and other resins: uniformly mixing the obtained copolyester with other resins to form a uniform mixture of the copolyester and the other resins; s3: preparing a double-layer polyester film: the polyester film having a two-layer structure of upper and lower layers is formed from a homogeneous mixture of a copolyester and other resins by a biaxial stretching method and a co-extrusion method. The double-layer polyester film has the advantages of excellent heat bonding property with a metal plate, excellent deep drawing processing resistance and complex deformation processing property, excellent corrosion resistance and the like, and can be widely applied to the metal packaging industry.

Description

Preparation method of double-layer polyester film and film-coated metal plate
Technical Field
The invention relates to the field of film-coated metal plates for metal packaging, in particular to a preparation method of a double-layer polyester film and a film-coated metal plate.
Background
In the metal can industry, the traditional method is to carry out can manufacturing and processing molding after the surface of a metal plate is coated, wherein the solvent type coating adopted in the coating treatment contains bisphenol A non-food safe substances, and a large amount of solvent is volatilized in the coating process to cause environmental protection problems and a large amount of energy consumption. In recent years, efforts have been made in the industry to find acceptable new materials to overcome the above difficulties.
The laminated iron is formed by directly bonding the flexible polyester film and the metal plate together in a hot melting mode, and can meet the requirements of downstream users on can manufacturing forming processing, differentiated printing, filling of various contents, high-temperature sterilization modes such as acid and alkali resistance and the like, and long shelf life.
With the trend of environmental protection policy and the rise of attention of people to food safety, the attention of the coated iron as an environment-friendly high-performance new material in the can making industry is higher and higher, and coated iron products of a part of enterprises enter the market for application in recent years. In order to meet the different requirements of different purposes, the raw materials and the film layer structure of the polyester film need to be optimally designed so as to meet different requirements of each downstream process.
Patent application No. CN1839036 discloses a film-coated metal plate and a drawn can used in the same, in which a double-layer film is laminated with a metal sheet, which is prone to generate defects such as delamination and falling-off in the can-making molding process, and a vinyl ionomer is used as an intermediate adhesive layer, which is poor in performance during filling and high-temperature sterilization.
Patent application No. CN 102432984A discloses a cast polyester film and a metal plate metal can used by the cast polyester film, and the cast polyester film is compounded with a metal thin plate, so that the performance of the prepared metal can is poor when the metal can is subjected to acid-base salt-resistant high-temperature sterilization during filling due to the insufficient barrier resistance.
Patent No. CN 106142782B discloses an iron-clad heat-sealable polyester film and a method for preparing the same, which is characterized in that a three-layer polyester film is laminated with a metal sheet, and the properties of the film are limited by its highly crystalline lower surface layer, resulting in insufficient processing and forming properties, and thus, the film is not suitable for deep drawing and complex deformation.
The patent application disclosed in the best CN 102463725A discloses a polyester film and a preparation method thereof, the polyester film is of a three-layer (ABA) structure and is used in the field of electronic tags, and the polyester film is characterized in that two surface layers are made of the same resin, so that the polyester film is difficult to simultaneously meet various performance requirements such as adhesion with a metal plate, contact with a mold, forming processing, contact with contents in a tank and the like, the performance is easily compromised, and the polyester film is not suitable for the tank making industry.
In the prior art, a single-layer film meeting the deep drawing processing requirement of a film-coated metal plate is deficient in filling acid-base salt-resistant high-temperature sterilization performance, and a multilayer film meeting the filling acid-base salt-resistant high-temperature sterilization requirement cannot meet the deep drawing processing requirement; the traditional double-layer film is easy to cause interlayer peeling of the film during deep processing and forming. The traditional film adopts a silicon-containing slice master batch mode to add the opening agent, so that the types of resin in the film are too diverse, and the film is not suitable for deep drawing processing.
Disclosure of Invention
The invention aims to provide a preparation method of a double-layer polyester film and a film-coated metal plate, which can meet the performance requirements of a metal container for food and beverage packaging, which meets the requirements of deep drawing and complex deformation.
In order to achieve the above object, the present invention adopts the following technical solutions.
According to an aspect of the present invention, there is provided a method for preparing a double-layered polyester film for middle and high-end food and beverage packaging, the double-layered polyester film comprising upper and lower layers, each of the upper and lower layers comprising a copolyester and other resins, the method comprising the steps of:
s1: preparation of modified copolyester:
carrying out copolymerization reaction on isophthalic acid, 1, 4-cyclohexanedimethanol and neopentyl glycol to obtain modified copolyester; in the copolymerization reaction, SiO is added in an in-situ polymerization mode2To obtain SiO with the mass fraction of 1200ppm2The copolyester resin of (a);
s2: preparation of a homogeneous mixture of copolyester and other resins:
uniformly mixing the obtained copolyester with other resins to form a uniform mixture of the copolyester and the other resins;
s3: preparing a double-layer polyester film:
the polyester film having a two-layer structure of upper and lower layers is formed from a homogeneous mixture of a copolyester and other resins by a biaxial stretching method and a co-extrusion method.
In the method for preparing the double-layered polyester film for middle and high-end food and beverage packages according to one aspect of the present invention, the co-extrusion and biaxial stretching methods are used to prepare the polyester film with a double-layered structure at the temperature of 250-280 ℃ in step S3.
In the method for preparing the double-layer polyester film applied to the middle-high-end food and beverage packaging according to one aspect of the invention, the other resin is selected from one of homopolyester resin, titanium-containing powdery master batch polyester resin and a mixture of homopolyester resin and golden master batch resin.
In the preparation method of the double-layer polyester film applied to the packaging of middle-high-end food and beverage according to one aspect of the invention, the proportion of other resins in the upper layer film is not more than 40 percent, and the proportion of other resins in the lower layer film is not more than 10 percent
Preferably, the proportion of other resins in the upper film is not more than 30%
In the preparation method of the double-layer polyester film applied to the packaging of middle and high-end food and beverage according to one aspect of the invention, the thickness of the upper layer is 8-25 μm, and the thickness of the lower layer is 3-6 μm.
Preferably, the thickness of the lower layer is 4-5 μm.
In the preparation method of the double-layer polyester film applied to the middle and high-end food and beverage packaging according to one aspect of the invention, the melting point of the copolyester is between 200 ℃ and 240 ℃.
Preferably, the melting point of the copolyester is between 210 ℃ and 230 ℃.
According to another aspect of the present invention, there is provided a film-coated metal plate comprising a metal substrate and the above-mentioned double-layer polyester film coated on a surface of the metal substrate.
In the film-coated metal plate according to another aspect of the present invention, the double-layer polyester film is thermally bonded to the surface of the metal substrate under a pressure of 2 to 10Kg and a temperature of 180 to 260 ℃.
In another aspect of the present invention, the coated metal sheet has a metal substrate thickness of 0.10 to 0.50mm, and the metal substrate is selected from a chromium-plated steel sheet, a tin-plated steel sheet, a low-tin steel sheet, a zinc-plated steel sheet, a cold-rolled steel sheet, and a stainless steel sheet.
According to still another aspect of the present invention, there is provided a metal container for packaging medium-high-end food and beverage, the metal container being made of the film-coated metal plate as described above.
Compared with the prior art, the invention has the following beneficial effects: the double-layer polyester film of the present invention has excellent thermal bonding properties with a metal plate, and is more characterized in that it can be used for deep drawing and various complicated deformation processes without delamination in the film, and the double-layer polyester film of the present invention imparts more excellent corrosion resistance than a single-layer film.
SiO2 is added into the polymer through in-situ polymerization, so that the crystallization performance of the polyester film is uniformly improved on the whole; and avoids the addition of high melting point resin into the film by improving the traditional way of adding SiO2 in the form of master batch. The two points obviously improve the comprehensive performance of the polyester film, and the complex processing resistance, the corrosion resistance and the like of the coated iron containing the film are obviously improved.
Detailed Description
The objects, features, and advantages of the present invention will become more apparent in the detailed description set forth below by way of non-limiting examples, the contents of which are sufficient to enable one skilled in the art to understand and practice the present invention.
Example 1
The production method of the polyester film adopts a biaxial stretching method, the production temperature is 250-280 ℃, the polyester film comprises copolyester and other resins, the copolyester is PET polyester modified by copolymerization of isophthalic acid, 1/4-cyclohexanedimethanol and neopentyl glycol, and the melting point is 230 ℃. The polyester film is manufactured by a co-extrusion method, and comprises an upper layer and a lower layer, wherein the upper layer and the lower layer are both a mixture of the copolyester and other resins which are uniformly mixed, and the upper layer and the lower layer are respectively 70% of the copolyester with the melting point of 230 ℃ and 30% of the homopolyester with the melting point of 262 ℃; 90 percent of copolyester with the melting point of 230 ℃ and 10 percent of lower film by mass percentThe homopolyester resin with the melting point of 262 ℃ in percentage by mass. The copolyester contained 1200ppm of SiO2。
Preparing a film-coated metal plate: and thermally laminating the prepared biaxially oriented polyester film on the surface of a 0.10-0.50 mm thin metal plate under the pressure of 2-10 Kg and the temperature of 180-260 ℃ to obtain the film-coated metal plate.
The preparation method of the double-layer polyester film comprises the following steps:
s1: preparation of modified copolyester:
carrying out copolymerization reaction on isophthalic acid, 1, 4-cyclohexanedimethanol and neopentyl glycol to obtain modified copolyester; in the copolymerization reaction, SiO is added in an in-situ polymerization mode2To obtain SiO with the mass fraction of 1200ppm2The copolyester resin of (a);
s2: preparation of a homogeneous mixture of copolyester and other resins:
uniformly mixing the obtained copolyester with other resins to form a uniform mixture of the copolyester and the other resins;
s3: preparing a double-layer polyester film:
the polyester film having a two-layer structure of upper and lower layers is formed from a homogeneous mixture of a copolyester and other resins by a biaxial stretching method and a co-extrusion method. The method is characterized in that: the double-layered polyester film comprises an upper layer and a lower layer, each of the upper layer and the lower layer comprises copolyester and other resin,
in step S3, a polyester film with a double-layer structure is prepared at the temperature of 250-280 ℃ by adopting a co-extrusion biaxial stretching method.
In the polyester film with the double-layer structure, the thickness of the upper layer is 8-25 mu m, and the thickness of the lower layer is 3-6 mu m.
Example 2
A production method of a polyester film, wherein the polyester film is manufactured by a biaxial stretching method at the manufacturing temperature of 250-280 ℃.
The polyester film comprises copolyester and other resins, wherein the copolyester is PET polyester copolymerized and modified by isophthalic acid, 1/4-cyclohexanedimethanol and neopentyl glycol, and the PET polyester is moltenThe point was 230 ℃. The polyester film is manufactured by a co-extrusion method, and comprises an upper layer and a lower layer, wherein the upper layer and the lower layer are both a mixture of the copolyester and other resins which are uniformly mixed, the upper layer and the lower layer are the copolyester with the mass percentage of 70% and the melting point of 230 ℃ and the titanium-containing white powder master batch polyester resin with the mass percentage of 30% and the melting point of 260 ℃, and TiO in the titanium-containing white powder master batch polyester resin2The content is 60 percent by mass; 95 percent of copolyester with the melting point of 230 ℃ and 5 percent of homopolyester with the melting point of 262 ℃ in mass percent of the lower film. The copolyester contained 1200ppm of SiO 2.
The preparation method of the double-layer polyester film and the film-coated metal plate is the same as that of example 1.
Example 3
A production method of a polyester film, wherein the polyester film is manufactured by a biaxial stretching method at the manufacturing temperature of 250-280 ℃.
The polyester film comprises copolyester and other resins, wherein the copolyester is PET polyester subjected to copolymerization modification by isophthalic acid, 1/4-cyclohexanedimethanol and neopentyl glycol, and the melting point of the PET polyester is 230 ℃. The polyester film is manufactured by a co-extrusion method, and comprises an upper layer and a lower layer, wherein the upper layer and the lower layer are both a mixture of the copolyester and other resins which are uniformly mixed, the upper layer and the lower layer are 70 mass percent of the copolyester with the melting point of 230 ℃ and 30 mass percent of other resins in the upper layer of the film, and the other resins comprise 1/3 mass percent of homopolyester with the melting point of 262 ℃ and 2/3 mass percent of golden polyester master batch resin with the melting point of 262 ℃; 98 percent of copolyester with the melting point of 230 ℃ and 2 percent of homopolyester resin with the melting point of 262 ℃ in percentage by mass of the lower film. The copolyester contained 1200ppm of SiO 2.
The preparation method of the double-layer polyester film and the film-coated metal plate is the same as that of example 1.
Example 4
The production process of polyester film with bi-directional stretching temperature of 250-280 deg.c includes copolymerization of polyester and other resinThe polyester is PET polyester modified by copolymerization of isophthalic acid, 1/4-cyclohexanedimethanol and neopentyl glycol, and the melting point of the polyester is 230 ℃. The polyester film is manufactured by a co-extrusion method, and comprises an upper layer and a lower layer, wherein the upper layer and the lower layer are both a mixture of the copolyester and other resins which are uniformly mixed, and the upper layer and the lower layer are respectively 90% of copolyester with a melting point of 230 ℃ by mass and 10% of homopolypolyester with a temperature of 262 ℃ by mass; 100 percent of copolyester with the melting point of 230 ℃ in mass percent of the lower film. The copolyester contained 1200ppm of SiO2。
The preparation method of the double-layer polyester film and the film-coated metal plate is the same as that of example 1.
Example 5
The production method of the polyester film adopts a biaxial stretching method, the production temperature is 250-280 ℃, the polyester film comprises copolyester and other resins, the copolyester is PET polyester modified by copolymerization of isophthalic acid, 1/4-cyclohexanedimethanol and neopentyl glycol, and the melting point is 230 ℃. The polyester film is manufactured by adopting an upper, middle and lower layer co-extrusion method, the upper, middle and lower layers are the mixture of the copolyester and the other resins which are uniformly mixed, the resins of the upper, middle and lower layers in the three-layer structure are completely the same, and 90 mass percent of the copolyester with the melting point of 230 ℃ and 10 mass percent of homopolyester with the temperature of 262 ℃ are contained in the upper, middle and lower layers of the film, and the film is of a substantially one-layer structure; 100 percent of copolyester with the melting point of 230 ℃ in mass percent of the lower film. The copolyester contained 1200ppm of SiO 2.
The three-layer polyester film and the coated metal sheet were prepared in the same manner as in example 1.
Example 6
The production process of polyester film with bi-directional stretching temperature of 250-280 deg.c includes copolymerization polyester of PET modified with isophthalic acid, 1/4-cyclohexane dimethanol and neopentyl glycol and melting point of 200 deg.c and other resin. The polyester film is manufactured by a co-extrusion method, and comprises an upper layer and a lower layer, wherein the upper layer and the lower layer are both a mixture of the copolyester and other resins which are uniformly mixed, and 70% of the copolyester with the melting point of 200 ℃ in mass percent and 30% of homopolypolyester with the temperature of 262 ℃ in mass percent are contained in the upper layer of the film; 90 percent of copolyester with the melting point of 200 ℃ and 10 percent of homopolyester resin with the temperature of 262 ℃ in percentage by mass of the lower film. The copolyester contained 1200ppm of SiO 2.
The preparation method of the double-layer polyester film and the film-coated metal plate is the same as that of example 1.
Example 7
The production process of polyester film with bi-directional stretching temperature of 250-280 deg.c includes copolymerization polyester of PET modified with isophthalic acid, 1/4-cyclohexane dimethanol and neopentyl glycol and melting point of 240 deg.c and other resin. The polyester film is manufactured by a co-extrusion method, and comprises an upper layer and a lower layer, wherein the upper layer and the lower layer are both a mixture of the copolyester and other resins which are uniformly mixed, and 70% of the copolyester with the melting point of 240 ℃ in mass percent and 30% of homopolypolyester with the temperature of 262 ℃ in mass percent are contained in the upper layer of the film; 90 percent of copolyester with the melting point of 240 ℃ and 10 percent of homopolyester resin with the melting point of 262 ℃ in percentage by mass of the lower film. The copolyester contained 1200ppm of SiO 2.
The preparation method of the double-layer polyester film and the film-coated metal plate is the same as that of example 1.
Example 8
The production process of polyester film with bi-directional stretching temperature of 250-280 deg.c includes copolymerization polyester of PET modified with isophthalic acid, 1/4-cyclohexane dimethanol and neopentyl glycol and melting point of 210 deg.c and other resin. The polyester film is manufactured by a co-extrusion method, and comprises an upper layer and a lower layer, wherein the upper layer and the lower layer are both a mixture of the copolyester and other resins which are uniformly mixed, and the upper layer of the film comprises 70% of the copolyester with the mass percent of 210 ℃ and 30% of homopolyester with the mass percent of 262 ℃; 90 percent of copolyester with the melting point of 210 ℃ and 10 percent of homopolyester resin with the temperature of 262 ℃ by mass percent of the lower film. The copolyester contained 1200ppm of SiO 2.
The preparation method of the double-layer polyester film and the film-coated metal plate is the same as that of example 1.
In the eight examples, the copolyester and other resins were blended to prepare a film having a two-layer structure, and the film had good moldability in both casting and biaxial stretching, and a polyester film having a small thickness was obtained. The polyester film and the metal plate have the advantages of excellent thermal bonding property, deep drawing processing resistance, complex deformation processing property, excellent corrosion resistance and the like, and can be widely applied to the metal packaging industry.
By adding SiO in the copolyester by in-situ synthesis2Because the common silicon-containing polyester chip is not used in the polyester film, the intervention of various polyester resins (the melting point is higher than 245 ℃) is avoided, the basic requirement of the opening agent is met, and the comprehensive performance of the film is obviously improved.
Finally, it should be noted that while the present invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be construed as limiting the present invention, and various equivalent changes and substitutions may be made therein without departing from the spirit of the present invention, and therefore, it is intended that all changes and modifications to the above embodiments within the spirit and scope of the present invention be covered by the appended claims.

Claims (13)

1. A preparation method of a double-layer polyester film is characterized by comprising the following steps: the double-layer polyester film comprises an upper layer and a lower layer, each of the upper layer and the lower layer comprises copolyester and homopolypolyester, and the preparation method comprises the following steps:
s1: preparation of modified copolyester:
carrying out copolymerization reaction on isophthalic acid, 1, 4-cyclohexanedimethanol and neopentyl glycol to obtain modified copolyester; in the copolymerization reaction, SiO is added in an in-situ polymerization mode2Obtaining SiO with the mass fraction of 1200ppm2The copolyester resin of (a);
s2: preparation of a homogeneous mixture of copolyester and homopolyester:
uniformly mixing the obtained copolyester with the homopolyester to form a uniform mixture of the copolyester and the homopolyester;
s3: preparing a double-layer polyester film:
a double-layer polyester film is formed by a uniform mixture of copolyester and homopolyester by adopting a co-extrusion and biaxial stretching method;
wherein the mass ratio of the homopolyester in the upper layer film is different from that of the homopolyester in the lower layer film.
2. The method for preparing a double-layered polyester film according to claim 1, wherein: in the step S3, a co-extrusion biaxial stretching method is adopted to prepare the double-layer polyester film at the temperature of 250-280 ℃.
3. The method for preparing a double-layered polyester film according to claim 1, wherein: the homopolyester also contains titanium dioxide master batch and/or golden polyester master batch.
4. The method for preparing a double-layered polyester film according to claim 1, wherein: the mass proportion of the homopolyester in the upper layer film is not more than 40 percent, and the mass proportion of the homopolyester in the lower layer film is not more than 10 percent.
5. The method for preparing a double-layered polyester film according to claim 1, wherein: the mass proportion of the homopolymerized polyester in the upper layer film is not more than 30 percent.
6. The method for preparing a double-layered polyester film according to claim 1, wherein: the thickness of the upper layer film is 8-25 mu m, and the thickness of the lower layer film is 3-6 mu m.
7. The method for preparing a double-layered polyester film according to claim 6, wherein: the thickness of the lower film is 4-5 mu m.
8. The method for preparing a double-layered polyester film according to claim 1, wherein: the melting point of the copolyester is between 200 ℃ and 240 ℃.
9. The method for preparing a double-layered polyester film according to claim 8, wherein: the melting point of the copolyester is between 210 ℃ and 230 ℃.
10. A coated metal sheet characterized by: comprising a metal substrate and a double-layer polyester film prepared by the preparation method of any one of claims 1 to 9 covering the surface of the metal substrate.
11. The coated metal sheet defined in claim 10, wherein: the double-layer polyester film is thermally bonded on the surface of the metal substrate at the temperature of 180-260 ℃ and at the temperature of 2-10 kgf.
12. The coated metal sheet defined in claim 10, wherein: the metal substrate is 0.10-0.50 mm thick and is selected from a chromium-plated steel sheet, a tin-plated steel sheet, a zinc-plated steel sheet, a cold-rolled steel sheet or a stainless steel sheet.
13. A metal container for packaging food and drink, characterized in that the metal container is made of the film-coated metal sheet according to any one of claims 10 to 12.
CN201811090577.0A 2018-09-19 2018-09-19 Preparation method of double-layer polyester film and film-coated metal plate Active CN110920166B (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05156040A (en) * 1991-12-03 1993-06-22 Teijin Ltd Polyester film for laminating molding processing of metallic plate
JPH07285206A (en) * 1994-04-19 1995-10-31 Toyobo Co Ltd Polyester composite film for laminating metal sheet
JPH10315412A (en) * 1997-05-19 1998-12-02 Teijin Ltd Polyester film for laminating metal plate
JPH11207909A (en) * 1998-01-26 1999-08-03 Teijin Ltd Laminated polyester film for metal sheet laminating molding processing

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05156040A (en) * 1991-12-03 1993-06-22 Teijin Ltd Polyester film for laminating molding processing of metallic plate
JPH07285206A (en) * 1994-04-19 1995-10-31 Toyobo Co Ltd Polyester composite film for laminating metal sheet
JPH10315412A (en) * 1997-05-19 1998-12-02 Teijin Ltd Polyester film for laminating metal plate
JPH11207909A (en) * 1998-01-26 1999-08-03 Teijin Ltd Laminated polyester film for metal sheet laminating molding processing

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