High-temperature-resistant polyester film and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant polyester film which can be of a single-layer structure or a three-layer structure, and the polyester film of the single-layer structure is prepared from 70wt%-100wt% of high-temperature-resistant PET functional master batch and PET for a common film; the polyester film with the three-layer structure comprises a surface layer A, a core layer B and a bottom layer C, the layer A and the layer C are arranged on the two sides of the layer B respectively and made of 70-100 wt% of high-temperature-resistant PET functional master batch and PET for common films, and the layer B is made of PET for common films. The invention further discloses a preparation method corresponding to the high-temperature-resistant polyester film with the single-layer structure and the three-layer structure. According to the polyester film, the optimized functional master batch is adopted, and compared with polyester films with other functional master batches or component raw materials, the polyester film obviously has more excellent high-temperature resistance and can be applied to high-temperature-resistant, high-mechanical-strength, chemical-corrosion-resistant and other environments in the application fields of electronics and electricity, automobiles, packaging, machinery, medical instruments, optics and the like.

Description

Technical Field

[0001] The present application relates to a polymer film that can be used in industries such as high temperature resistance, high mechanical strength, and chemical corrosion resistance, and in particular to a high temperature resistant polyester film and a preparation method thereof. Background Art

[0002] High-temperature-resistant polyester films (such as polyethylene terephthalate (PET) films) possess a range of excellent properties. For example, they maintain stable physical properties even in high-temperature environments, exhibit high tensile strength and tear resistance, a hard surface, and good impact resistance, making them suitable for applications requiring resistance to mechanical stress. They also possess excellent electrical insulation properties and are widely used as insulating materials in the electrical and electronic fields. They also exhibit excellent chemical corrosion resistance, resisting corrosion from a variety of chemicals, including oils, acids, and bases. Their low hygroscopicity allows them to maintain good mechanical strength and electrical properties even in humid environments. Their high transparency makes them widely used in optical devices and packaging materials. Their surface can be easily processed by coating, printing, and metallization to enhance their functionality and added value. High-temperature-resistant polyester films are widely used in the electrical and electronic fields as electrical insulation materials, and are widely used as insulation layers in motors, transformers, and capacitors. They can also be used to form insulation layers for flexible printed circuit boards (FPCs), cables, and wires. High-temperature-resistant polyester films are commonly used in high-temperature packaging for food, pharmaceuticals, and other applications, particularly those requiring high strength and corrosion resistance. High-temperature-resistant polyester film is used as a key component in optical devices such as backlights for liquid crystal displays (LCDs) and protective films for solar panels. Due to its high transparency and excellent surface finish, high-temperature-resistant polyester film is used in printed labels, advertising decorations, and protective layers for cards. High-temperature-resistant polyester film is also used in the aerospace and automotive industries as a thermal and insulating material for high-temperature environments. Due to its unique combination of properties, high-temperature-resistant polyester film has a wide range of applications in various fields, particularly where high strength, heat resistance, and corrosion resistance are required.

[0003] The prior art describes a variety of different high-temperature-resistant polyester films and their application examples. For example, CN109054311B discloses a high-temperature-resistant polyester film and its preparation method. The film comprises two surface layers, one on top and one on the bottom, and a core layer in the middle. The surface layers have the same composition, consisting of 90-97% by weight of PEN chips, 0-7% by weight of PET chips, and 3% by weight of a PET anti-blocking agent masterbatch. The core layer comprises 50-70% by weight of PEN chips, 25-40% by weight of PET chips, and 5-10% by weight of a modified montmorillonite masterbatch. The modified montmorillonite masterbatch is primarily made of the following components in the following weight percentages: 10% by weight of modified montmorillonite and 90% by weight of PET.

[0004] CN 117024806 B discloses a method for preparing a high-temperature resistant enhanced PET release film, which comprises the following steps, in parts by weight: taking 20-35 parts of PET, adding 5-10 parts of dimethylamide, heating and stirring, and obtaining a mixture A; mixing a NaOH solution, cerium-barium co-modified zirconium dioxide particles, and sodium hexametaphosphate to obtain a mixture B; adding 0.5-1 parts of a plasticizer and 1-5 parts of the mixture B to the mixture A, stirring at a speed of 1500-2000 rpm for 2 hours; ultrasonically dispersing for 25-40 minutes; standing for 24-48 hours to degas; casting onto a horizontal glass plate, and drying at 130-170°C for 12-24 hours to obtain the high-temperature resistant enhanced PET release film.

[0005] In existing polyester films, high-temperature resistance is often enhanced by adding modifying materials. While these modification processes can reduce agglomeration and improve dispersibility, good dispersibility does not guarantee uniform distribution of the modified material in the melt. Especially when small amounts of modifying components are added, the poor fluidity of the melt requires prolonged heating and stirring to evenly disperse the small amount of modified material in the molten polyester. However, prolonged high-temperature stirring reduces the crystallinity of the polyester, making it difficult to produce a product of uniform quality. Summary of the Invention

[0006] The technical problem to be solved by the present application is to provide a high-temperature resistant polyester film and a preparation method thereof, so as to reduce or avoid the problems mentioned above.

[0007] To solve the above technical problems, the present application proposes a high-temperature resistant polyester film, which is a single-layer polyester film, wherein the single-layer polyester film is made of 70wt%-100wt% of a high-temperature resistant PET functional masterbatch and ordinary film-use PET, wherein the high-temperature resistant PET functional masterbatch is prepared from the following raw materials in parts by weight: 50-100 parts by weight of terephthalic acid, 20-45 parts by weight of ethylene glycol, 5-10 parts by weight of dimethyl 2,6-naphthalene dicarboxylate, 0.02-0.04 parts by weight of acetic anhydride, 0.03-0.05 parts by weight of acetone, 0.005-0.01 parts by weight of antimony dioxide, 0.01-0.03 parts by weight of triethyl phosphate, 0.01-0.03 parts by weight of sodium dodecylbenzenesulfonate, 0.05-0.10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.10-0.15 parts by weight of ethanol, and 0.01-0.03 parts by weight of cellulose acetate.

[0008] The present application also provides another high-temperature resistant polyester film, which is a three-layer co-extruded structure, including a surface layer A, a core layer B and a bottom layer C, characterized in that the A layer and the C layer are respectively arranged on both sides of the B layer and are both made of 70wt%-100wt% of a high-temperature resistant PET functional masterbatch and ordinary film PET, and the B layer is made of ordinary film PET, wherein the high-temperature resistant PET functional masterbatch is prepared from the following raw materials in parts by weight: 50-100 parts by weight of terephthalic acid, 20-45 parts by weight of ethylene glycol, 5-10 parts by weight of dimethyl 2,6-naphthalene dicarboxylate, 0.02-0.04 parts by weight of acetic anhydride, 0.03-0.05 parts by weight of acetone, 0.005-0.01 parts by weight of antimony dioxide, 0.01-0.03 parts by weight of triethyl phosphate, 0.01-0.03 parts by weight of sodium dodecylbenzenesulfonate, 0.05-0.10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.10-0.15 parts by weight of ethanol, and 0.01-0.03 parts by weight of cellulose acetate.

[0009] Preferably, the thickness of the high temperature resistant polyester film is 10-500 μm and the width is 1500-5000 mm.

[0010] Preferably, the thickness of the high temperature resistant polyester film is 50-250 μm and the width is 1500-5000 mm.

[0011] Preferably, the thickness of the A layer and the C layer of the high temperature resistant polyester film is 5-25 μm, and the thickness of the B layer is 5-450 μm.

[0012] Preferably, the thickness of the A layer and the C layer of the high temperature resistant polyester film is 10-25 μm, and the thickness of the B layer is 30-200 μm.

[0013] The present application also provides a preparation method corresponding to the above-mentioned single-layer high-temperature resistant polyester film, comprising the following steps: mixing the prepared high-temperature resistant PET functional masterbatch with ordinary film PET slices according to 70wt%-100wt% of the total mass of the film layer, and making a single-layer polyester film through melt extrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting.

[0014] The present application also provides another preparation method corresponding to the above-mentioned three-layer structure of high-temperature resistant polyester film, comprising the following steps: adding the prepared high-temperature resistant PET functional masterbatch in an amount of 70wt%-100wt% of the total mass of the surface layer, uniformly mixing it with PET polyester chips for ordinary film, and using it as the surface layer raw material; using PET chips for ordinary film as the core layer raw material, and making a polyester film with an ABC three-layer structure through melt co-extrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting.

[0015] Preferably, the above preparation method further includes the steps of preparing a high-temperature resistant PET functional masterbatch: uniformly mixing 0.02-0.04 parts by weight of acetic anhydride and 0.03-0.05 parts by weight of acetone, then adding 0.005-0.01 parts by weight of antimony dioxide, and uniformly mixing and reacting for more than 30 minutes to prepare a solution A for use; uniformly mixing 0.01-0.03 parts by weight of sodium dodecylbenzenesulfonate, 0.05-0.10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.10-0.15 parts by weight of ethanol and 0.01-0.03 parts by weight of cellulose acetate, heating to 50° C., and standing for hydrolysis for more than 1 hour to prepare a solution B for use; and uniformly mixing 50-100 parts by weight of terephthalic acid, 20- 45 parts by weight of ethylene glycol and 5-10 parts by weight of dimethyl 2,6-naphthalenedicarboxylate are added to an esterification tank and mixed uniformly. Solution A is then stirred uniformly and added to the esterification tank for reaction. The reaction temperature is 180-260 degrees Celsius and the gauge pressure is 0.2-0.3 MPa. When the water output reaches 1200 ml, the pressure is released to normal pressure, and the reaction product is filtered and then added to a polycondensation tank. Solution B is then stirred uniformly and added to the polycondensation tank. 0.01-0.03 parts by weight of triethyl phosphate is added to the polycondensation tank, and the mixture is stirred at normal pressure for 30-60 minutes. The mixture is reacted at a temperature of 230-280 degrees Celsius and a pressure below 100 Pa for 3-5 hours. The reaction product in the polycondensation tank is extruded and sliced. The slices are then placed in a vacuum drying tank for drying and reaction for more than 10 hours to obtain the high-temperature resistant PET functional masterbatch.

[0016] Preferably, the drying temperature of the vacuum drying tank is 230-250 degrees Celsius and the pressure is below 100 Pa.

[0017] This application adopts an optimized esterification dispersion catalytic system and adds a grid-like polysiloxane chain at the beginning of the condensation stage when the molecular chain is relatively small, so that it can be relatively easily dispersed into the masterbatch without affecting the crystallinity of the polyester, thereby achieving excellent high-temperature resistance.

[0018] In addition, the polyester film of the present application uses an optimized functional masterbatch. Compared with polyester films made of other functional masterbatches or ingredients, it has significantly better high-temperature resistance and can be used in high-temperature resistance, high mechanical strength, chemical corrosion resistance and other environments in application fields such as electronics and electrical, automobiles, packaging, machinery, medical equipment, and optics. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following drawings are only intended to illustrate and explain the present application and are not intended to limit the scope of the present application.

[0020] Figure 1 Shown is a schematic diagram of the cross-sectional structure of a high-temperature resistant polyester film according to a specific embodiment of the present application.

[0021] Figure 2 Shown is a schematic diagram of the cross-sectional structure of a high-temperature resistant polyester film according to another specific embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to have a clearer understanding of the technical features, objectives and effects of this application, the specific implementation of this application is now described with reference to the accompanying drawings, wherein the same components are marked with the same reference numerals.

[0023] In view of the problems of the prior art, the present application proposes a high-temperature resistant polyester film and a preparation method thereof. The high-temperature resistant polyester film can maintain its performance unchanged at higher temperatures and can be applied to electronic and electrical, automotive, packaging, machinery, medical equipment, optics and other application fields.

[0024] like Figure 1 , which shows a schematic cross-sectional structure diagram of a heat-resistant polyester film according to a specific embodiment of the present application. The heat-resistant polyester film according to this embodiment is a single-layer polyester film, which can be made of 70wt%-100wt% of a heat-resistant PET functional masterbatch and ordinary film-grade PET.

[0025] The single-layer polyester film preferably has a thickness of 10-500 μm, more preferably 50-250 μm, and a width of 1500-5000 mm.

[0026] like Figure 2 FIG2 shows a schematic cross-sectional structure diagram of a heat-resistant polyester film according to another specific embodiment of the present application. The heat-resistant polyester film of this embodiment has a three-layer co-extruded structure, comprising a surface layer A, a core layer B, and a bottom layer C. Layers A and C are disposed on either side of layer B and can be made of 70 wt% to 100 wt% of a heat-resistant PET functional masterbatch and conventional film-grade PET. Layer B is made of conventional film-grade PET.

[0027] The total thickness of the three-layer polyester film is preferably 10-500 μm, wherein the thicknesses of layers A and C are 5-25 μm, and the thickness of layer B is 5-450 μm. Furthermore, the total thickness of the three-layer polyester film is preferably 50-250 μm, wherein the thicknesses of layers A and C are 10-25 μm, and the thickness of layer B is 30-200 μm. The width of the three-layer polyester film is 1500-5000 mm.

[0028] Furthermore, the high-temperature resistant PET functional masterbatch used in the high-temperature resistant polyester film can be prepared from the following raw materials in parts by weight: 50-100 parts by weight of terephthalic acid, 20-45 parts by weight of ethylene glycol, 5-10 parts by weight of dimethyl 2,6-naphthalene dicarboxylate, 0.02-0.04 parts by weight of acetic anhydride, 0.03-0.05 parts by weight of acetone, 0.005-0.01 parts by weight of antimony dioxide, 0.01-0.03 parts by weight of triethyl phosphate, 0.01-0.03 parts by weight of sodium dodecylbenzenesulfonate, 0.05-0.10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.10-0.15 parts by weight of ethanol, and 0.01-0.03 parts by weight of cellulose acetate. The cellulose acetate is commercially available powder having an acetyl content of 37% to 40%.

[0029] The preparation method of the high temperature resistant PET functional masterbatch of the present application comprises the following steps:

[0030] 0.02-0.04 parts by weight of acetic anhydride and 0.03-0.05 parts by weight of acetone are uniformly mixed, and then 0.005-0.01 parts by weight of antimony dioxide is added. The mixture is uniformly mixed and reacted for more than 30 minutes to prepare a solution A for use.

[0031] 0.01-0.03 parts by weight of sodium dodecylbenzenesulfonate, 0.05-0.10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.10-0.15 parts by weight of ethanol, and 0.01-0.03 parts by weight of cellulose acetate are uniformly mixed, heated to 50-60° C., and allowed to stand for hydrolysis for more than 1 hour to prepare Solution B for later use.

[0032] Add 50-100 parts by weight of terephthalic acid, 20-45 parts by weight of ethylene glycol, and 5-10 parts by weight of dimethyl 2,6-naphthalene dicarboxylate to an esterification tank and mix uniformly. Then, stir solution A evenly and add it to the esterification tank for reaction. The reaction temperature is 180-260°C and the gauge pressure is 0.2-0.3 MPa. When the water output reaches 1200 ml, release the pressure to atmospheric pressure. Filter the reaction product and transfer it to a polycondensation tank.

[0033] Then, solution B is stirred evenly and added to a polycondensation tank. 0.01-0.03 parts by weight of triethyl phosphate is added to the polycondensation tank. Stir at normal pressure for 30-60 minutes, and react at a temperature of 230-280°C and a pressure below 100 Pa for 3-5 hours. The reaction product in the polycondensation tank is extruded and sliced.

[0034] The slices are placed in a vacuum drying tank for drying and reacting for more than 10 hours to obtain the high-temperature resistant PET functional masterbatch of the present application. The drying temperature of the vacuum drying tank is 230-250 degrees Celsius and the pressure is below 100 Pa.

[0035] Solution A forms a partial suspension containing antimony acetate, which is fully dispersed throughout the system during the esterification process, serving as a catalyst for multi-system esterification and improving the high-temperature resistance of the subsequent polymerization product. In solution B, 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone hydrolyzes in the alkaline environment of sodium dodecylbenzenesulfonate and ethanol to produce silanols, which polymerize into polysiloxane chains. These are then dispersed into the cellulose acetate emulsion, forming a grid-like dispersion. During the polycondensation reaction, the dispersed polysiloxane chains firmly connect the PET and PEN, significantly improving the high-temperature resistance of the functional masterbatch. The small amount of unhydrolyzed 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone still provides UV protection, further enhancing the anti-aging properties of the functional masterbatch.

[0036] Example 1

[0037] 0.02 parts by weight of acetic anhydride and 0.03 parts by weight of acetone were uniformly mixed, and then 0.005 parts by weight of antimony dioxide was added, and the mixture was uniformly mixed and reacted for 30 minutes to prepare a solution A for use.

[0038] 0.01 parts by weight of sodium dodecylbenzenesulfonate, 0.05 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.10 parts by weight of ethanol, and 0.01 parts by weight of cellulose acetate were uniformly mixed, heated to 50° C., and allowed to stand for hydrolysis for 1 hour to prepare Solution B for later use.

[0039] Add 50 parts by weight of terephthalic acid, 20 parts by weight of ethylene glycol, and 5 parts by weight of dimethyl 2,6-naphthalene dicarboxylate to an esterification tank and mix thoroughly. Then, stir Solution A thoroughly and add it to the esterification tank for reaction. The reaction temperature is 180°C and the gauge pressure is 0.2 MPa. When the water output reaches 1200 ml, release the pressure to atmospheric pressure. Filter the reaction product and transfer it to a polycondensation tank.

[0040] Then, solution B was stirred evenly and added to the polycondensation tank, and 0.01 parts by weight of triethyl phosphate was added to the polycondensation tank. The mixture was stirred at normal pressure for 30 minutes and reacted at a temperature of 230° C. and a pressure of 100 Pa for 3 hours. The reaction product in the polycondensation tank was extruded and sliced.

[0041] The slices were placed in a vacuum drying tank for drying and reacting for 10 hours to obtain the high-temperature resistant PET functional masterbatch of the present application. The drying temperature of the vacuum drying tank was 230 degrees Celsius and the pressure was 100 Pa.

[0042] The prepared high-temperature resistant PET functional masterbatch was mixed with conventional PET chips at 70, 85, or 100 weight percent of the total film mass. The resulting single-layer polyester film was produced through melt extrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting. The resulting films had a width of 1500 mm and a thickness of 30 μm.

[0043] The performance parameters of the three single-layer polyester films prepared in Example 1 were measured, among which the tensile strengths at 25°C were 285 MPa, 293 MPa, and 297 MPa, respectively; the transverse thermal shrinkages at 120°C and 30 minutes were all less than 0.01%; the transverse thermal shrinkages at 200°C and 30 minutes were 0.06%, 0.05%, and 0.04%, respectively; the light transmittances were 93.1%, 93.2%, and 93.3%, respectively; and the tensile strengths at 300°C were 167 MPa, 170 MPa, and 174 MPa, respectively.

[0044] Example 2

[0045] 0.03 parts by weight of acetic anhydride and 0.04 parts by weight of acetone were uniformly mixed, and then 0.008 parts by weight of antimony dioxide was added, and the mixture was uniformly mixed and reacted for 40 minutes to prepare a solution A for use.

[0046] 0.02 parts by weight of sodium dodecylbenzenesulfonate, 0.08 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.12 parts by weight of ethanol, and 0.02 parts by weight of cellulose acetate were uniformly mixed, heated to 55° C., and allowed to stand for hydrolysis for 1.5 hours to prepare Solution B for later use.

[0047] 80 parts by weight of terephthalic acid, 35 parts by weight of ethylene glycol, and 8 parts by weight of dimethyl 2,6-naphthalene dicarboxylate were added to an esterification tank and mixed evenly. Solution A was then stirred evenly and added to the esterification tank for reaction. The reaction temperature was 220°C and the gauge pressure was 0.25 MPa. When the water output reached 1200 ml, the pressure was released to atmospheric pressure. The reaction product was filtered and then transferred to a polycondensation tank.

[0048] Then, solution B was stirred evenly and added to the polycondensation tank, and 0.02 parts by weight of triethyl phosphate was added to the polycondensation tank. The mixture was stirred at normal pressure for 45 minutes, and then reacted at a temperature of 255° C. and a pressure of 90 Pa for 4 hours. The reaction product in the polycondensation tank was extruded and sliced.

[0049] The slices were placed in a vacuum drying tank and dried for 11 hours to obtain the high-temperature resistant PET functional masterbatch of the present application. The drying temperature of the vacuum drying tank was 240 degrees Celsius and the pressure was 90 Pa.

[0050] The prepared high-temperature resistant PET functional masterbatch was mixed with conventional PET chips at 70, 85, or 100 weight percent of the total film mass. The resulting single-layer polyester film was produced through melt extrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting. The resulting films had a width of 3000 mm and a thickness of 100 μm.

[0051] The performance parameters of the three single-layer polyester films prepared in Example 2 were measured, among which the tensile strengths at 25°C were 287 MPa, 297 MPa, and 301 MPa, respectively; the transverse thermal shrinkages at 120°C and 30 minutes were all less than 0.01%; the transverse thermal shrinkages at 200°C and 30 minutes were 0.05%, 0.04%, and 0.03%, respectively; the light transmittances were 92.7%, 92.8%, and 92.9%, respectively; and the tensile strengths at 300°C were 177 MPa, 176 MPa, and 179 MPa, respectively.

[0052] Example 3

[0053] 0.04 parts by weight of acetic anhydride and 0.05 parts by weight of acetone were uniformly mixed, and then 0.003 parts by weight of antimony dioxide was added, and the mixture was uniformly mixed and reacted for 50 minutes to prepare a solution A for use.

[0054] 0.03 parts by weight of sodium dodecylbenzenesulfonate, 0.10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.15 parts by weight of ethanol, and 0.03 parts by weight of cellulose acetate were uniformly mixed, heated to 60° C., and allowed to stand for hydrolysis for 2 hours to prepare Solution B for later use.

[0055] 100 parts by weight of terephthalic acid, 45 parts by weight of ethylene glycol, and 10 parts by weight of dimethyl 2,6-naphthalate were added to an esterification tank and mixed evenly. Solution A was then stirred evenly and added to the esterification tank for reaction. The reaction temperature was 260°C and the gauge pressure was 0.3 MPa. When the water output reached 1200 ml, the pressure was released to atmospheric pressure. The reaction product was filtered and then transferred to a polycondensation tank.

[0056] Then, solution B was stirred evenly and added to the polycondensation tank, and 0.03 parts by weight of triethyl phosphate was added to the polycondensation tank. The mixture was stirred at normal pressure for 60 minutes, and then reacted at a temperature of 280° C. and a pressure of 80 Pa for 5 hours. The reaction product in the polycondensation tank was extruded and sliced.

[0057] The slices were placed in a vacuum drying tank for drying and reacting for 12 hours to obtain the high-temperature resistant PET functional masterbatch of the present application. The drying temperature of the vacuum drying tank was 250 degrees Celsius and the pressure was 80 Pa.

[0058] The prepared high-temperature resistant PET functional masterbatch was mixed with conventional PET chips at 70, 85, or 100 weight percent of the total film mass. The resulting single-layer polyester film was produced through melt extrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting. The resulting films had a width of 5000 mm and a thickness of 250 μm.

[0059] The performance parameters of the three single-layer polyester films prepared in Example 3 were measured, among which the tensile strengths at 25°C were 301 MPa, 302 MPa, and 305 MPa, respectively; the transverse thermal shrinkages at 120°C and 30 minutes were all less than 0.01%; the transverse thermal shrinkages at 200°C and 30 minutes were 0.02%, 0.01%, and 0.03%, respectively; the light transmittances were 94.2%, 94.3%, and 94.1%, respectively; and the tensile strengths at 300°C were 171 MPa, 177 MPa, and 183 MPa, respectively.

[0060] With reference to the preparation process parameters of Examples 1-3, some raw material ratios were adjusted and comparative experiments were carried out respectively.

[0061] Comparative Example 1

[0062] A functional masterbatch was prepared using the same process parameters as in Example 1. Solution A was omitted during the preparation process, but was replaced with 0.005 parts by weight of antimony acetate during the step of adding solution A. 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone was omitted from the preparation of solution B. The remaining process parameters and raw material weights were the same as in Example 1.

[0063] As in Example 1, the prepared functional masterbatch was mixed with PET chips for ordinary film at 70wt%, 85wt% and 100wt% of the total mass of the film layer, respectively, and then melt-extruded, die-cast, stretched horizontally and longitudinally, cooled and shaped, and wound and slit to make a single-layer polyester film.

[0064] The performance parameters of the three single-layer polyester films prepared in Comparative Example 1 were measured, among which the tensile strengths at 25°C were 288 MPa, 209 MPa, and 213 MPa, respectively; the transverse thermal shrinkages at 120°C and 30 minutes were 6.7%, 6.6%, and 6.5%, respectively; the transverse thermal shrinkages at 200°C and 30 minutes were 10.3%, 10.0%, and 9.8%, respectively; the light transmittances were 82.3%, 82.4%, and 82.1%, respectively; and the tensile strengths at 300°C were 12 MPa, 13 MPa, and 15 MPa, respectively.

[0065] Comparative Example 2

[0066] A functional masterbatch was prepared using the same process parameters as in Example 2. Solution A was omitted during the preparation process, but was replaced with 0.008 parts by weight of antimony acetate during the step of adding solution A. When preparing solution B, neither 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone nor cellulose acetate was added. The remaining process parameters and raw material weights were the same as in Example 2.

[0067] As in Example 2, the prepared functional masterbatch was mixed with PET chips for ordinary film at 70wt%, 85wt% and 100wt% of the total mass of the film layer, respectively, and then melt-extruded, die-cast, stretched horizontally and longitudinally, cooled and shaped, and wound and slit to make a single-layer polyester film.

[0068] The performance parameters of the three single-layer polyester films prepared in Comparative Example 2 were measured, among which the tensile strengths at 25°C were 219 MPa, 218 MPa, and 221 MPa, respectively; the transverse thermal shrinkages at 120°C and 30 minutes were 2.5%, 2.8%, and 2.7%, respectively; the transverse thermal shrinkages at 200°C and 30 minutes were 3.3%, 3.4%, and 3.8%, respectively; the light transmittances were 87.8%, 87.3%, and 87.2%, respectively; and the tensile strengths at 300°C were 42 MPa, 43 MPa, and 45 MPa, respectively.

[0069] Comparative Example 3

[0070] A functional masterbatch was prepared using the same process parameters as in Example 3. Solution A was omitted during the preparation process, but was replaced with 0.01 parts by weight of antimony acetate during the step of adding solution A. When preparing solution B, neither 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone nor sodium dodecylbenzenesulfonate was added. The remaining process parameters and raw material weights were the same as in Example 3.

[0071] As in Example 3, the prepared functional masterbatch was mixed with PET chips for ordinary film at 70wt%, 85wt% and 100wt% of the total mass of the film layer, respectively, and then melt-extruded, die-cast, stretched horizontally and longitudinally, cooled and shaped, and wound and slit to make a single-layer polyester film.

[0072] The performance parameters of the three single-layer polyester films prepared in Comparative Example 3 were measured, among which the tensile strengths at 25°C were 188 MPa, 191 MPa, and 195 MPa, respectively; the transverse thermal shrinkages at 120°C and 30 minutes were 5.5%, 5.2%, and 4.6%, respectively; the transverse thermal shrinkages at 200°C and 30 minutes were 7.9%, 7.7%, and 7.6%, respectively; the light transmittances were 83.2%, 83.3%, and 83.0%, respectively; and the tensile strengths at 300°C were 20 MPa, 22 MPa, and 24 MPa, respectively.

[0073] The weight parameters of the raw materials of Examples 1-3 and Comparative Examples 1-3 are shown in the following table. Among them, some of the raw material names in each Example and Comparative Example are represented by the following abbreviations or codes.

[0074] Terephthalic acid: PTA Ethylene glycol: EG Dimethyl 2,6-naphthalene dicarboxylate: NDC

[0075] Triethyl phosphate: TEP Sodium dodecylbenzenesulfonate: SDBS

[0076] 2-Hydroxy-4-(3-triethoxysilylpropoxy)benzophenone: Y Cellulose acetate: CA

[0077]

[0078] Examples 1-3 and Comparative Examples 1-3 were prepared according to the aforementioned preparation methods. The underlined parts in the table indicate that the corresponding components were not added during the preparation process. In Comparative Examples 1-3, antimony acetate was used instead of antimony dioxide in Examples 1-3.

[0079] The performance parameters of the polyester films obtained by stretching the functional masterbatches prepared in Examples 1-3 and Comparative Examples 1-3 at a ratio of 100 wt % are shown in the following table.

[0080]

[0081] Through experimental data, the inventors analyzed and believed that the present application adopts an optimized esterification dispersion catalytic system and adds a grid-like polysiloxane chain at the beginning of the polycondensation stage when the molecular chain is relatively small, so that it can be dispersed into the masterbatch relatively easily without affecting the crystallinity of the polyester, thereby achieving excellent high-temperature resistance. Further experiments show that Examples 1-3 still did not show obvious shrinkage after being baked at a high temperature of 300 degrees Celsius for 30 minutes. In addition, in the accelerated aging experiment, the average number of color spots of Examples 1-3 over 6 months was much less than that of Comparative Examples 1-3 (less than 10%), indicating that the polyester film of the present application has excellent anti-aging properties, excellent corrosion resistance, and stable quality.

[0082] Based on the functional masterbatches prepared in Examples 1-3, three-layer polyester films were prepared.

[0083] Example 4

[0084] The functional masterbatch slices prepared in Example 1 were added in an amount of 70 wt% of the total mass of the surface layer and uniformly mixed with PET polyester slices for ordinary film to serve as the surface layer raw material; the ordinary film PET slices were used as the core layer raw material, and a polyester film with an ABC three-layer structure was prepared by melt coextrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting.

[0085] The thickness of the prepared polyester film A layer is 10 μm, the thickness of the B layer is 30 μm, the thickness of the C layer is 10 μm, the total thickness is 50 μm, and the width is 1500 mm.

[0086] Example 5

[0087] The functional masterbatch slices prepared in Example 2 were added in an amount of 85wt% of the total mass of the surface layer and uniformly mixed with PET polyester slices for ordinary film to serve as the surface layer raw material; the ordinary film PET slices were used as the core layer raw material, and a polyester film with an ABC three-layer structure was prepared by melt coextrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting.

[0088] The thickness of the prepared polyester film A layer is 20 μm, the thickness of the B layer is 110 μm, the thickness of the C layer is 20 μm, the total thickness is 150 μm, and the width is 3000 mm.

[0089] Example 6

[0090] The functional masterbatch slices prepared in Example 3 were added in an amount of 100wt% of the total mass of the surface layer and used as the surface layer raw material; ordinary film PET slices were used as the core layer raw material, and an ABC three-layer polyester film was made by melt coextrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting.

[0091] The thickness of the prepared polyester film A layer is 25 μm, the thickness of the B layer is 200 μm, the thickness of the C layer is 25 μm, the total thickness is 250 μm, and the width is 5000 mm.

[0092] Comparative Examples 4-6

[0093] Based on the functional masterbatch of Comparative Examples 1-3 and using the same technical parameters as Examples 4-6, polyester films with three-layer structures of Comparative Examples 4-6 were prepared accordingly.

[0094] The performance parameters of the three-layer polyester films of Examples 4-6 and Comparative Examples 4-6 are shown in the following table.

[0095]

[0096] Through comparison of experimental data, the three-layer polyester film of the present application, when using an optimized functional masterbatch, has significantly better high-temperature resistance than polyester films made of other functional masterbatches or ingredients. It can be used to prepare polymer products with high temperature resistance, high mechanical strength, and chemical corrosion resistance in the fields of electronics, automobiles, packaging, machinery, medical equipment, optics, and other application fields.

[0097] Those skilled in the art should understand that although this application is described in terms of multiple embodiments, not each embodiment contains only one independent technical solution. This description is only for the sake of clarity. Those skilled in the art should understand the description as a whole and understand the scope of protection of this application by considering the technical solutions involved in each embodiment as being combinable into different embodiments.

[0098] The above description is only an illustrative embodiment of the present application and is not intended to limit the scope of the present application. Any equivalent changes, modifications and combinations made by any person skilled in the art without departing from the concept and principle of the present application shall fall within the scope of protection of the present application.

Claims

1. A high temperature resistant polyester film, which is a single-layer polyester film, characterized in that: The single-layer polyester film is made of 70-100 wt% of a high-temperature resistant PET functional masterbatch and PET for ordinary films. The high-temperature resistant PET functional masterbatch is made of the following raw materials in parts by weight: 50-100 parts by weight of terephthalic acid, 20-45 parts by weight of ethylene glycol, 5-10 parts by weight of dimethyl 2,6-naphthalene dicarboxylate, 0.02-0.04 parts by weight of acetic anhydride, 0.03-0.05 parts by weight of acetone, 0.005-0.01 parts by weight of antimony dioxide, 0.01-0.03 parts by weight of triethyl phosphate, 0.01-0.03 parts by weight of sodium dodecylbenzenesulfonate, 0.05-0.10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.10-0.15 parts by weight of ethanol, and 0.01-0.03 parts by weight of cellulose acetate.

2. A high temperature resistant polyester film with a three-layer co-extrusion structure, comprising a surface layer A, a core layer B and a bottom layer C, characterized in that: The A layer and the C layer are respectively arranged on both sides of the B layer and are made of 70wt%-100wt% of a high temperature resistant PET functional masterbatch and a common film PET. The B layer is made of a common film PET. The high temperature resistant PET functional masterbatch is prepared from the following raw materials in parts by weight: 50-100 parts by weight of terephthalic acid, 20-45 parts by weight of ethylene glycol, 5-10 parts by weight of dimethyl 2,6-naphthalene dicarboxylate, 0.02-0.04 parts by weight of acetic anhydride, 0.03-0.05 parts by weight of acetone, 0.005-0.01 parts by weight of antimony dioxide, 0.01-0.03 parts by weight of triethyl phosphate, 0.01-0.03 parts by weight of sodium dodecylbenzenesulfonate, 0.05-0.10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.10-0.15 parts by weight of ethanol, and 0.01-0.03 parts by weight of cellulose acetate.

3. The high temperature resistant polyester film according to claim 1 or 2, characterized in that: The thickness of the high-temperature resistant polyester film is 10-500 μm, and the width is 1500-5000 mm.

4. The high temperature resistant polyester film according to claim 1 or 2, characterized in that: The thickness of the high-temperature resistant polyester film is 50-250 μm, and the width is 1500-5000 mm.

5. The high temperature resistant polyester film according to claim 2, characterized in that: The thickness of the A layer and the C layer of the high-temperature resistant polyester film is 5-25 μm, and the thickness of the B layer is 5-450 μm.

6. The high temperature resistant polyester film according to claim 2, wherein: The thickness of the A layer and the C layer of the high-temperature resistant polyester film is 10-25 μm, and the thickness of the B layer is 30-200 μm.

7. The method for preparing a high-temperature resistant polyester film according to claim 1 comprises the following steps: mixing the prepared high-temperature resistant PET functional masterbatch with ordinary film PET chips according to 70wt%-100wt% of the total mass of the film layer, and preparing a single-layer polyester film by melt extrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting.

8. The method for preparing a high-temperature resistant polyester film according to claim 2 comprises the following steps: uniformly mixing the prepared high-temperature resistant PET functional masterbatch with PET polyester chips for ordinary film in an amount of 70 wt% to 100 wt% of the total mass of the surface layer, and using the PET chips for ordinary film as the raw material for the surface layer; and using the PET chips for ordinary film as the raw material for the core layer, and preparing a polyester film with an ABC three-layer structure through melt coextrusion, die casting, transverse and longitudinal stretching, cooling and shaping, and winding and slitting.

9. The method according to claim 7 or 8, further comprising the step of preparing a high temperature resistant PET functional masterbatch: 0.02-0.04 parts by weight of acetic anhydride and 0.03-0.05 parts by weight of acetone are uniformly mixed, and then 0.005-0.01 parts by weight of antimony dioxide is added. The mixture is uniformly mixed and reacted for more than 30 minutes to prepare a solution A for use; 0.01-0.03 parts by weight of sodium dodecylbenzenesulfonate, 0.05-0.10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, 0.10-0.15 parts by weight of ethanol, and 0.01-0.03 parts by weight of cellulose acetate are uniformly mixed, heated to 50° C., and allowed to stand for hydrolysis for more than 1 hour to prepare a solution B for later use; 50-100 parts by weight of terephthalic acid, 20-45 parts by weight of ethylene glycol, and 5-10 parts by weight of dimethyl 2,6-naphthalene dicarboxylate are added to an esterification tank and uniformly mixed. Solution A is then stirred uniformly and added to the esterification tank for reaction. The reaction temperature is 180-260 degrees Celsius and the gauge pressure is 0.2-0.3 MPa. When the water output reaches 1200 ml, the pressure is released to normal pressure. The reaction product is filtered and then fed into a polycondensation tank. Then, solution B is stirred evenly and added to a polycondensation tank, and 0.01-0.03 parts by weight of triethyl phosphate is added to the polycondensation tank. The mixture is stirred at normal pressure for 30-60 minutes, and the reaction is carried out at a temperature of 230-280°C and a pressure below 100 Pa for 3-5 hours. The reaction product in the polycondensation tank is extruded and sliced. The slices were placed in a vacuum drying tank for drying and reacting for more than 10 hours to obtain the high-temperature resistant PET functional masterbatch.

10. The method according to claim 9, wherein The drying temperature of the vacuum drying tank is 230-250 degrees Celsius and the pressure is below 100 Pa.

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