Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides an environment-friendly flexible matte polyester film for a door plate, which is made of a specific material into a three-layer structure, has good flexibility, overcomes the problem that the local position adhesion fastness of the polyester film is not enough in the mould pressing process, and simultaneously solves the problem that the corner position of PVC is whitish in the plastic suction mould pressing process.
The environment-friendly flexible matte polyester film for the door plate comprises a core layer, an upper surface layer compounded on the upper surface of the core layer and a lower surface layer compounded on the lower surface of the core layer; the core layer is composed of a crystalline PET homopolymer and a PET copolymer modified by 1, 4-cyclohexanedimethanol and 1, 4-butanediol.
Furthermore, the upper surface layer mainly comprises a crystalline PET homopolymer and a micron inorganic substance modified crystalline PET copolymer; preferably, the lower surface layer mainly comprises crystalline PET copolymer modified by micron inorganic matter and isophthalic acid and 1, 4-butanediol, or mainly comprises crystalline PET homopolymer and micron inorganic matter and isophthalic acid and 1, 4-butanediol modified crystalline PET copolymer.
Furthermore, the mass percentage of the crystalline PET homopolymer, the 1, 4-cyclohexanedimethanol and 1, 4-butanediol modified PET copolymer in the core layer is 0-50%: 50-100%; the mass percentage of the crystalline PET homopolymer and the micron inorganic substance modified crystalline PET copolymer in the upper surface layer is 70-80%: 20-30%; preferably, the mass percentage of the crystalline PET homopolymer in the lower surface layer, the crystalline PET copolymer modified by the micron inorganic matter, the isophthalic acid and the 1, 4-butanediol is 70-80% to 20-30%.
Further, the micron inorganic substance modified crystalline PET copolymer is prepared according to the following steps: mixing the micron inorganic substance, terephthalic acid and ethylene glycol according to the weight ratio of 1.0-2.0%: 50-70%: 30-45% of the raw materials are mixed, esterified and polycondensed; preferably, the 1, 4-cyclohexanedimethanol and 1, 4-butanediol modified PET copolymer is prepared by the following steps: mixing terephthalic acid, ethylene glycol, 1, 4-cyclohexane glycol and 1, 4-butanediol according to the mass ratio of 50-70:5-15:10-25:15-25, esterifying and polycondensing; preferably, the PET copolymer modified by micron inorganic matter, isophthalic acid and 1, 4-butanediol is prepared by the following steps: mixing the micron inorganic substance, terephthalic acid, isophthalic acid, ethylene glycol and 1-4 butanediol according to the mass ratio of 0.2-0.3:20-55:13-40:15-20:15-30, esterifying and polycondensing.
Furthermore, the esterification conditions of the micron inorganic substance modified crystalline PET copolymer are as follows: the pressure is 0.1-0.15 MPa, the temperature is 255-270 ℃, the reaction is carried out for 100-150 min, and the polycondensation reaction conditions are as follows: the vacuum degree is 45-55 pa, the temperature is 275-285 ℃, and the reaction time is 3-4 h; preferably, the esterification conditions of the PET copolymer modified by 1, 4-cyclohexanedimethanol and 1, 4-butanediol are as follows: the pressure is 0.1-0.15 MPa, the temperature is 255-270 ℃, the reaction is carried out for 100-150 min, and the polycondensation reaction conditions are as follows: the vacuum degree is 45-55 pa, the temperature is 275-285 ℃, and the reaction time is 3-4 h; preferably, the esterification conditions of the micron inorganic substance, the isophthalic acid and the 1, 4-butanediol modified PET copolymer are as follows: the pressure is 0.1-0.15 MPa, the temperature is 255-270 ℃, the reaction is carried out for 100-150 min, and the polycondensation reaction conditions are as follows: the vacuum degree is 45-55 pa, the temperature is 275-285 ℃, and the reaction time is 3-4 h.
Furthermore, the melting point of the crystalline PET homopolymer is 256-262 ℃, and the intrinsic viscosity is 0.66-0.70 dl/g; preferably, the melting point of the micron inorganic substance modified crystalline PET copolymer is 252-262 ℃, and the intrinsic viscosity is 0.66-0.70 dl/g; preferably, the melting point of the 1, 4-cyclohexanedimethanol and 1, 4-butanediol modified PET copolymer is 210-235 ℃, and the intrinsic viscosity is 0.80-0.85 dl/g; preferably, the melting point of the micrometer inorganic substance, isophthalic acid and 1, 4-butanediol modified PET copolymer is 200-235 ℃, and the intrinsic viscosity is 0.8-1.0 dl/g.
Specifically, the micron inorganic matter is selected from sodium silicate and SiO2One or more than two of calcium carbonate and montmorillonite; preferably, the particle size of the micron inorganic substance is 3.5-4.5 μm, and more preferably 3.5-4.0 μm.
Specifically, the density of the environment-friendly flexible matte film for the door panel is 1.25-1.30 g/m2The thickness is 15-22 mu m; the thickness of the upper surface layer and the lower surface layer is 1.5-4.0 μm.
The invention also aims to provide a method for preparing the environment-friendly flexible matte polyester film for the door panel, which comprises the following steps:
s1, taking a crystalline PET homopolymer, a 1, 4-cyclohexanedimethanol and 1, 4-butanediol modified PET copolymer as a core layer raw material, and performing pre-crystallization, drying, melting and extrusion;
s2, taking a mixture of a crystalline PET homopolymer and a micron inorganic substance modified crystalline PET copolymer as an upper surface layer raw material, and performing pre-crystallization, drying, melting and extrusion;
s3, taking a crystalline PET copolymer modified by micron inorganic matters, isophthalic acid and 1, 4-butanediol as a lower surface layer raw material, or taking a mixture of a crystalline PET homopolymer and the crystalline PET copolymer modified by the micron inorganic matters, the isophthalic acid and the 1, 4-butanediol as a lower surface layer raw material, and pre-crystallizing, drying, melting and extruding the mixture;
and S4, co-extruding and molding the core layer raw material, the upper surface layer raw material and the lower surface layer raw material which are subjected to melt extrusion through a composite die head, respectively compounding the upper surface layer raw material and the lower surface layer raw material on the upper surface and the lower surface of the core layer raw material, quenching to form a casting sheet, preheating the casting sheet, longitudinally stretching to obtain a primary membrane, preheating again, transversely stretching to obtain a base membrane, cooling, cutting, eliminating static electricity and rolling to obtain the composite membrane.
Further, the melting temperature of the S1-S3 is 260-280 ℃, and a single-screw extruder is used for extruding; preferably, the longitudinal stretching multiple in S4 is 2.5-3.4, and the transverse stretching multiple is 3.4-4.4; preferably, the temperature for rapidly cooling into the cast sheet in the step S4 is 15-40 ℃; the preheating temperature is 50-80 ℃; the temperature during longitudinal stretching is 60-88 ℃; preferably, the temperature for preheating again is 90-100 ℃; the temperature during transverse stretching is 100-110 ℃.
The invention adopts the technical scheme to achieve the following beneficial effects:
the core layer of the flexible matte polyester film for the door panel is the PET copolymer modified by 1, 4-cyclohexanedimethanol and 1, 4-butanediol, so that the common polyester film does not have flexibility, and the phenomenon of insufficient adhesion fastness cannot occur in the compression molding process after the door panel is coated with a film; because the upper surface layer mainly comprises the crystalline PET homopolymer and the crystalline PET copolymer modified by the micron inorganic substance, the micron inorganic substance ensures that the flexible matte film for the door plate has the effects of scratch resistance and good appearance.
Detailed Description
The present invention will be described in more detail with reference to specific preferred embodiments, but the present invention is not limited to the following embodiments.
The crystalline PET homopolymer used in the present invention may be FG600 produced by instrumented company or polyester chip 5011 produced by three-lane company.
When the invention is used for preparing the micron inorganic substance modified crystal type PET copolymer, the used micron inorganic substance can also use sodium silicate, calcium carbonate and montmorillonite.
Example 1
The flexible matte polyester film for the door panel, described in example 1, was prepared according to the following steps:
1) the PET copolymer modified by crystalline PET homopolymer, 1, 4-cyclohexanedimethanol and 1, 4-butanediol according to the mass ratio of 20%: 80% of the mixture is mixed to be used as a core layer raw material, the core layer raw material is pre-crystallized and dried to the moisture content of below 100ppm, the core layer raw material is melted at 260-280 ℃, the core layer raw material is extruded by a single-screw extruder, and the extruded polymer in a molten state enters a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
the preparation method of the PET copolymer (melting point 235 ℃ and specific viscosity 0.8) modified by 1, 4-cyclohexanedimethanol and 1, 4-butanediol is as follows: carrying out esterification reaction on terephthalic acid, ethylene glycol, 1, 4-cyclohexanediol and 1, 4-butanediol at a mass ratio of 55:15:10:20 under the pressure of 0.1-0.15 MPa and at the temperature of 255-270 ℃ for 100-150 min; and then carrying out polycondensation reaction under the conditions of vacuum degree of 45-55 pa and temperature of 275-285 ℃, wherein the reaction time is 3-4 h.
2) 80% by mass of a crystalline PET homopolymer (melting point 260 ℃ and intrinsic viscosity 0.66) and a crystalline PET copolymer modified with a micron inorganic substance (melting point 260 ℃ and intrinsic viscosity 0.66): mixing 20 percent of the mixture serving as an upper surface layer raw material, pre-crystallizing and drying the mixture until the water content is below 100ppm, melting the mixture at 260-280 ℃, extruding the molten mixture by using a single-screw extruder, and feeding the extruded molten mixture into a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
wherein the micron inorganic modified crystalline PET copolymer (melting point 260 ℃ and intrinsic viscosity 0.66) is prepared according to a method comprising the following steps: mixing a micron inorganic substance, terephthalic acid and ethylene glycol according to a mass ratio of 1.0:50:30, and carrying out esterification reaction for 100-150 min under the conditions of a pressure of 0.1-0.15 MPa and a temperature of 255-270 ℃; and then carrying out polycondensation reaction under the conditions of vacuum degree of 45-55 pa and temperature of 275-285 ℃, wherein the reaction time is 3-4 h.
3) Taking a micron inorganic substance, isophthalic acid and 1, 4-butanediol modified crystalline PET copolymer (melting point 235 ℃ and intrinsic viscosity 0.8) as a lower surface layer raw material, carrying out vacuum drum pre-crystallization and drying treatment, then feeding the raw material into a single-screw extruder, carrying out melt extrusion at 275 ℃, and feeding the extruded molten mixture into a die head through a pre-filter with the precision of 60 microns, a metering pump and a main filter with the precision of 25 microns;
the preparation method of the micron inorganic matter, isophthalic acid and 1, 4-butanediol modified crystalline PET copolymer (melting point 235 ℃ and intrinsic viscosity 0.8) comprises the following steps: mixing montmorillonite with the particle size of 3.5 microns, terephthalic acid, isophthalic acid, ethylene glycol and 1, 4-butanediol according to the mass ratio of 0.3:55:13:15:16.7, and carrying out esterification reaction for 100-150 min at the pressure of 0.1-0.15 MPa and the temperature of 255-270 ℃; and then carrying out polycondensation reaction under the conditions of vacuum degree of 45-55 pa and temperature of 275-285 ℃, wherein the reaction time is 3-4 h.
The particle size of the micron inorganic substance is 3.5-4.5 um, and more preferably 3.5-4.0 um.
4) Merging the core layer raw material, the upper surface layer raw material and the lower surface layer raw material which are subjected to melt extrusion through a composite die head, then carrying out co-extrusion molding, respectively compounding the upper surface layer raw material and the lower surface layer raw material on the upper surface and the lower surface of the core layer raw material, and rapidly cooling the materials on a quenching roller at 20 ℃ to form a casting sheet; preheating the cast sheet obtained by cooling at 60 ℃, then longitudinally stretching at 80 ℃ to obtain a primary membrane sheet with the stretching ratio of 2.8, preheating the longitudinally stretched primary membrane sheet again at 95 ℃, and then transversely stretching at 100 ℃ to obtain a base membrane with the stretching ratio of 3.6. And cooling the obtained base film to normal temperature, cutting, eliminating static electricity and rolling to obtain the flexible matte polyester film for the door panel.
Through detection, the flexible matte polyester film with the three-layer structure prepared in the embodiment 1 has good flexibility, overcomes the problem of insufficient adhesion fastness of local positions of the polyester film in the molding process, simultaneously solves the problem of whitening of corner positions of PVC in the plastic suction molding process, and has good environmental protection (PET is an environmental-friendly material), the film has the thickness of 20 microns, the thickness of the lower surface layer is 2.5 microns, the thickness of the upper surface layer is 2.2 microns, and the thickness of the core layer is 15.3 microns.
Example 2
The flexible matte polyester film for the door panel, described in example 2, was prepared according to the following steps:
1) the PET copolymer modified by crystalline PET homopolymer, 1, 4-cyclohexanedimethanol and 1, 4-butanediol according to the mass ratio of 20%: 80% of the mixture is mixed to be a core layer raw material, the core layer raw material is pre-crystallized and dried to the moisture content of below 100ppm, the core layer raw material is melted at the temperature of 260-280 ℃, the core layer raw material is extruded by a single-screw extruder, and the extruded polymer in a molten state enters a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
2) 70% by mass of a crystalline PET homopolymer (melting point 260 ℃ and intrinsic viscosity 0.66) and a crystalline PET copolymer modified with a micron inorganic substance (melting point 260 ℃ and intrinsic viscosity 0.66): mixing 30 percent of the mixture as an upper surface layer raw material, performing pre-crystallization and drying treatment on the mixture until the water content is below 100ppm, melting the mixture at 260-280 ℃, extruding the molten mixture by using a single-screw extruder, and feeding the extruded molten mixture into a die head through a pre-filter with the precision of 60 microns, a metering pump and a main filter with the precision of 60 microns;
wherein the micron inorganic modified crystalline PET copolymer (melting point 260 ℃ and intrinsic viscosity 0.66) is prepared according to a method comprising the following steps: mixing a micron inorganic substance, terephthalic acid and ethylene glycol according to a mass ratio of 2.0:70:45, and carrying out esterification reaction for 100-150 min under the conditions of a pressure of 0.1-0.15 MPa and a temperature of 255-270 ℃; and then carrying out polycondensation reaction under the conditions of vacuum degree of 45-55 pa and temperature of 275-285 ℃, wherein the reaction time is 3-4 h.
3) A crystalline PET copolymer (melting point 235 degrees, intrinsic viscosity 0.8) modified by a crystalline PET homopolymer (melting point 260 degrees, intrinsic viscosity 0.66) and a micron inorganic substance, isophthalic acid and 1, 4-butanediol, wherein the mass fraction of the crystalline PET copolymer is 80%: mixing the raw materials with the proportion of 20 percent as the raw material of the lower surface layer, performing vacuum drum pre-crystallization and drying treatment, then feeding the mixture into a single-screw extruder, performing melt extrusion at 275 ℃, and feeding the extruded mixture in a molten state into a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
4) merging the melted and extruded core layer raw material, the upper surface layer raw material and the lower surface layer raw material through a composite die head, then co-extruding and molding, respectively compounding the upper surface layer raw material and the lower surface layer raw material on the upper surface and the lower surface of the core layer raw material, and rapidly cooling on a quenching roller at 25 ℃ to form a casting sheet; preheating the cast sheet obtained by cooling at 65 ℃, then longitudinally stretching at 85 ℃ to obtain a primary membrane sheet, wherein the stretching ratio is 3.0, preheating the longitudinally stretched primary membrane sheet again at 98 ℃, and then transversely stretching at 105 ℃ to obtain a base membrane, wherein the stretching ratio is 3.6. And cooling, cutting, eliminating static electricity and winding the obtained base film to obtain the flexible matte polyester film for the door panel.
Through detection, the prepared flexible matte polyester film with the three-layer structure is good in flexibility, the problem that the adhesion fastness of a local position of the polyester film is not enough in the mould pressing process is solved, the problem that edges and corners of PVC are whitish in the plastic suction mould pressing process is solved, the environment is protected, the thickness of the film is 20 micrometers, the thickness of a lower surface layer is 3 micrometers, the thickness of an upper surface layer is 2 micrometers, and the thickness of a core layer is 15 micrometers.
The crystalline PET copolymer modified with the micron inorganic substance, isophthalic acid and 1, 4-butanediol used in this example was obtained in the same manner as in example 1.
In this example, the PET copolymer modified with 1, 4-cyclohexanedimethanol or 1, 4-butanediol was prepared in the same manner as in example 1.
Example 3
The flexible matte polyester film for the door panel, described in example 3, was prepared according to the following steps:
1) the PET copolymer modified by crystalline PET homopolymer, 1, 4-cyclohexanedimethanol and 1, 4-butanediol according to the mass ratio of 20%: 80 percent of the mixture is used as a core layer raw material, the core layer raw material is pre-crystallized and dried until the moisture content is below 100ppm, the core layer raw material is melted at 260 to 280 ℃, the core layer raw material is extruded by a single-screw extruder, and the extruded polymer in a molten state enters a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
2) 75% by mass of a crystalline PET homopolymer (melting point 260 ℃ and intrinsic viscosity 0.66) and a crystalline PET copolymer modified with a micron inorganic substance (melting point 260 ℃ and intrinsic viscosity 0.66): mixing 25 percent of the mixture serving as an upper surface layer raw material, performing pre-crystallization and drying treatment on the mixture until the water content is below 100ppm, melting the mixture at 260-280 ℃, extruding the molten mixture by using a single-screw extruder, and feeding the extruded molten mixture into a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 30 micrometers;
wherein the micron inorganic modified crystalline PET copolymer (melting point 260 ℃ and intrinsic viscosity 0.66) is prepared according to a method comprising the following steps: mixing the micron inorganic substance, terephthalic acid and ethylene glycol according to the mass ratio of 1.5:60:38, and carrying out esterification reaction for 100-150 min under the conditions that the pressure is 0.1-0.15 MPa and the temperature is 255-270 ℃; and then carrying out polycondensation reaction under the conditions of vacuum degree of 45-55 pa and temperature of 275-285 ℃, wherein the reaction time is 3-4 h.
3) 75% by mass of a crystalline PET homopolymer (melting point 260 ℃ and intrinsic viscosity 0.66) and a crystalline PET copolymer (melting point 235 ℃ and intrinsic viscosity 0.8) modified with a micron inorganic substance, isophthalic acid and 1, 4-butanediol: mixing the raw materials with the proportion of 25 percent to be used as a lower surface layer raw material, performing vacuum drum pre-crystallization and drying treatment, then feeding the mixture into a single-screw extruder, performing melt extrusion at 275 ℃, and feeding the extruded mixture in a molten state into a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
4) merging the core layer raw material, the upper surface layer raw material and the lower surface layer raw material which are subjected to melt extrusion through a composite die head, then carrying out co-extrusion molding, respectively compounding the upper surface layer raw material and the lower surface layer raw material on the upper surface and the lower surface of the core layer raw material, and rapidly cooling the materials on a quenching roller at 28 ℃ to form a casting sheet; preheating the cast sheet obtained by cooling at 67 ℃, longitudinally stretching at 86 ℃ to obtain a primary membrane sheet with the stretching ratio of 3.2, preheating the longitudinally stretched primary membrane sheet again at 100 ℃, and transversely stretching at 106 ℃ to obtain a base membrane with the stretching ratio of 3.8. And cooling, cutting, eliminating static electricity and winding the obtained base film to obtain the flexible matte polyester film for the door panel.
The detection proves that the prepared flexible matte polyester film with the three-layer structure has good flexibility, overcomes the problem of insufficient adhesion fastness of local positions in the process of mould pressing of the polyester film, solves the problem of whitening of corner positions in the process of plastic suction mould pressing of PVC, and is good in environmental protection, the thickness of the film is 19 micrometers, the thickness of the lower surface layer is 3.8 micrometers, the thickness of the upper surface layer is 2.3 micrometers, and the thickness of the core layer is 12.9 micrometers.
The crystalline PET copolymer modified with the micron inorganic substance, isophthalic acid and 1, 4-butanediol used in this example was obtained in the same manner as in example 1.
In this example, the PET copolymer modified with 1, 4-cyclohexanedimethanol or 1, 4-butanediol was prepared in the same manner as in example 1.
Example 4
The flexible matte polyester film for the door panel, described in example 4, was prepared according to the following steps:
1) the PET copolymer modified by crystalline PET homopolymer, 1, 4-cyclohexanedimethanol and 1, 4-butanediol according to the mass ratio of 20%: 80% of the mixture is mixed to be a core layer raw material, the core layer raw material is pre-crystallized and dried to the moisture content of below 100ppm, the core layer raw material is melted at the temperature of 260-280 ℃, the core layer raw material is extruded by a single-screw extruder, and the extruded polymer in a molten state enters a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
2) 78% by mass of a crystalline PET homopolymer (melting point 260 ℃ and intrinsic viscosity 0.66) and a crystalline PET copolymer modified with a micron inorganic substance (melting point 260 ℃ and intrinsic viscosity 0.66): mixing 22 percent of the mixture serving as an upper surface layer raw material, performing pre-crystallization and drying treatment on the mixture until the moisture content is below 100ppm, melting the mixture at 260-280 ℃, extruding the mixture by using a single-screw extruder, and feeding the extruded mixture in a molten state into a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 40 micrometers;
wherein the micron inorganic modified crystalline PET copolymer (melting point 260 ℃ and intrinsic viscosity 0.66) is prepared according to a method comprising the following steps: mixing a micron inorganic substance, terephthalic acid and ethylene glycol according to a mass ratio of 1.5:60:40, and performing an esterification reaction for 100-150 min under the conditions that the pressure is 0.1-0.15 MPa and the temperature is 255-270 ℃; and then carrying out polycondensation reaction under the conditions of vacuum degree of 45-55 pa and temperature of 275-285 ℃, wherein the reaction time is 3-4 h.
3) A crystalline PET copolymer (melting point 235 degrees, intrinsic viscosity 0.8) modified with a crystalline PET homopolymer (melting point 260 degrees, intrinsic viscosity 0.66) and a micromineral, isophthalic acid, and 1, 4-butanediol, in a mass fraction of 78%: mixing the materials in a proportion of 22 percent to serve as a lower surface layer raw material, performing vacuum drum pre-crystallization and drying treatment, then feeding the mixture into a single-screw extruder, performing melt extrusion at 275 ℃, and feeding the extruded mixture in a molten state into a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
4) merging the core layer raw material, the upper surface layer raw material and the lower surface layer raw material which are subjected to melt extrusion through a composite die head, then carrying out co-extrusion molding, respectively compounding the upper surface layer raw material and the lower surface layer raw material on the upper surface and the lower surface of the core layer raw material, and rapidly cooling the materials on a quenching roller at 30 ℃ to obtain a casting sheet; preheating the cast sheet obtained by cooling at 68 ℃, then longitudinally stretching at 88 ℃ to obtain a primary membrane sheet, wherein the stretching ratio is 3.4, preheating the longitudinally stretched primary membrane sheet again at 102 ℃, and then transversely stretching at 108 ℃ to obtain a base membrane, wherein the stretching ratio is 3.9. And cooling, cutting, eliminating static electricity and winding the obtained base film to obtain the flexible matte polyester film for the door panel.
The detection proves that the prepared flexible matte polyester film with the three-layer structure has good flexibility, overcomes the problem of insufficient adhesion fastness of local positions in the process of mould pressing of the polyester film, solves the problem of whitening of corner positions in the process of plastic suction mould pressing of PVC, and is good in environmental protection, the thickness of the film is 18 microns, the thickness of the lower surface layer is 4 microns, the thickness of the upper surface layer is 2.5 microns, and the thickness of the core layer is 11.5 microns.
The crystalline PET copolymer modified with the micron inorganic substance, isophthalic acid and 1, 4-butanediol used in this example was obtained in the same manner as in example 1.
In this example, the PET copolymer modified with 1, 4-cyclohexanedimethanol or 1, 4-butanediol was obtained in the same manner as in example 1.
Example 5
The flexible matte polyester film for the door panel, described in example 5, was prepared according to the following steps:
1) the PET copolymer modified by crystalline PET homopolymer, 1, 4-cyclohexanedimethanol and 1, 4-butanediol according to the mass ratio of 20%: 80% of the mixture is mixed to be a core layer raw material, the core layer raw material is pre-crystallized and dried to the moisture content of below 100ppm, the core layer raw material is melted at the temperature of 260-280 ℃, the core layer raw material is extruded by a single-screw extruder, and the extruded polymer in a molten state enters a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
2) 72% by mass of a crystalline PET homopolymer (melting point 260 ℃ and intrinsic viscosity 0.66) and a crystalline PET copolymer modified with a micron inorganic substance (melting point 260 ℃ and intrinsic viscosity 0.66): mixing 28 percent of the mixture serving as an upper surface layer raw material, performing pre-crystallization and drying treatment on the mixture until the water content is below 100ppm, melting the mixture at 260-280 ℃, extruding the molten mixture by using a single-screw extruder, and feeding the extruded molten mixture into a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 20 micrometers;
wherein the micron inorganic modified crystalline PET copolymer (melting point 260 ℃ and intrinsic viscosity 0.66) is prepared according to a method comprising the following steps: mixing a micron inorganic substance, terephthalic acid and ethylene glycol according to a mass ratio of 1.8:65:42, and carrying out esterification reaction for 100-150 min under the conditions that the pressure is 0.1-0.15 MPa and the temperature is 255-270 ℃; and then carrying out polycondensation reaction under the conditions of vacuum degree of 45-55 pa and temperature of 275-285 ℃, wherein the reaction time is 3-4 h.
3) 72% by mass of a crystalline PET homopolymer (melting point 260 ℃ and intrinsic viscosity 0.66) and a crystalline PET copolymer (melting point 235 ℃ and intrinsic viscosity 0.8) modified with a micron inorganic substance, isophthalic acid and 1, 4-butanediol: mixing the raw materials with the proportion of 28 percent as the lower surface layer raw material, performing vacuum drum pre-crystallization and drying treatment, then feeding the mixture into a single-screw extruder, performing melt extrusion at 275 ℃, and feeding the extruded mixture in a molten state into a die head through a pre-filter with the precision of 60 micrometers, a metering pump and a main filter with the precision of 25 micrometers;
4) merging the core layer raw material, the upper surface layer raw material and the lower surface layer raw material which are subjected to melt extrusion through a composite die head, then carrying out co-extrusion molding, respectively compounding the upper surface layer raw material and the lower surface layer raw material on the upper surface and the lower surface of the core layer raw material, and rapidly cooling the materials on a quenching roller at 22 ℃ to form a casting sheet; preheating the cast sheet obtained by cooling at 63 ℃, then longitudinally stretching at 72 ℃ to obtain a primary membrane sheet with the stretching ratio of 2.9, preheating the longitudinally stretched primary membrane sheet again at 96 ℃, and then transversely stretching at 103 ℃ to obtain a base membrane with the stretching ratio of 3.7. And cooling, cutting, eliminating static electricity and winding the obtained base film to obtain the flexible matte polyester film for the door panel.
Through detection, the prepared flexible matt polyester film with the three-layer structure is good in flexibility, overcomes the problem that the adhesion fastness of a local position of the polyester film is not enough in the mould pressing process, solves the problem that edge and corner positions of PVC are whitish in the plastic suction mould pressing process, is good in environmental protection, and is 22 micrometers thick, 3.2 micrometers thick in the lower surface layer, 2.7 micrometers thick in the upper surface layer and 16.1 micrometers thick in the core layer.
The crystalline PET copolymer modified with the micron inorganic substance, isophthalic acid and 1, 4-butanediol used in this example was obtained in the same manner as in example 1.
In this example, the PET copolymer modified with 1, 4-cyclohexanedimethanol or 1, 4-butanediol was prepared in the same manner as in example 1.
Second, performance test
The performance of each of examples 1-5 was tested, and the specific data are shown in table 1:
TABLE 1 Performance test data in examples 1-5
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, so that any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.