High temperature resistant, low outgassing, transparent polyester film and method of making same

Abstract

The application discloses a high-temperature-resistant and low-extraction transparent polyester film and a preparation method thereof. The polyester film comprises a surface layer, a core layer and a pre-coating layer which are sequentially arranged. Raw material components of the surface layer comprise inorganic particles, polyester chips and an antistatic agent. Raw material components of the core layer are polyester chips. Raw material components of the pre-coating layer comprise polyurethane glue, a curing agent, inorganic particles, a cross-linking agent, an antistatic agent and deionized water. The transparent polyester film provided by the application has high light transmittance, good high-temperature resistance, excellent comprehensive performance and is particularly suitable for the fields of MLCC release film base film, protective film, adhesive tape and optical base film.

Description

Technical Field

[0001] This invention relates to the field of thin film materials, and in particular to a high-temperature resistant, low-emission transparent polyester film and its preparation method. Background Technology

[0002] Transparent polyester (PET) film is widely used in various fields such as MLCC release film, polarizer protective film, food processing protective film, tape, and optical base film. Currently, PET films available in the domestic market are generally used in the low-to-mid-end market due to their poor performance, while the high-end PET film market is largely monopolized by foreign companies such as Japan, the United States, and South Korea. Therefore, developing polyester film products with properties such as high temperature resistance, low exudation, and high light transmittance is of great significance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a high-temperature resistant, low-exudation transparent polyester film and its preparation method, addressing the shortcomings of the prior art.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a high-temperature resistant, low-exudation transparent polyester film, comprising a surface layer, a core layer, and a pre-coating layer stacked sequentially.

[0005] The raw material components of the surface layer include inorganic particles, polyester chips, and antistatic agents;

[0006] The raw material component of the core layer is polyester chips;

[0007] The raw material components of the pre-coating include polyurethane adhesive, curing agent, inorganic particles, crosslinking agent, antistatic agent and deionized water.

[0008] Preferably, the raw material components in the surface layer, by weight percentage, are as follows:

[0009] Inorganic particles 0.5-2.0%, antistatic agent 0.5-2%, the remainder is polyester chips.

[0010] Preferably, the raw material components in the pre-coating layer, by weight percentage, are as follows:

[0011] The composition consists of 25% polyurethane adhesive, 2-8% curing agent, 0.1-1% inorganic particles, 0.005-0.1% crosslinking agent, 0.2-1% antistatic agent, and the remainder is deionized water.

[0012] Preferably, the viscosity of the polyester chips in the surface layer is 0.70-0.82 dl / g, and the viscosity of the polyester chips in the core layer is 0.62-0.72 dl / g.

[0013] Preferably, the polyester chips in the outer layer and the core layer are selected from one or more of polyethylene terephthalate (PET), polyethylene terephthalate-1,4-cyclohexanediethanol (PETG), polyethylene naphthalate (PEN), and polyethylene terephthalate-1,4-cyclohexanediethanol (PCT).

[0014] Preferably, the inorganic particles in the surface layer and the core layer are selected from one or more of silicon dioxide, calcium carbonate, barium sulfate, and aluminum oxide.

[0015] Preferably, the inorganic particles in the surface layer are a mixture of silicon dioxide and calcium carbonate, and the mass ratio of silicon dioxide to calcium carbonate is 1:1.

[0016] The silica consists of irregular spheres with a particle size of 50-200 nm, and the calcium carbonate consists of irregular spheres with a particle size of 150-300 nm.

[0017] Preferably, the antistatic agent in the surface layer is selected from cationic, nonionic, anionic, and conductive polymers.

[0018] Preferably, the curing agent in the pre-coating is one of hydroxyl acrylic resin isocyanate, pyridine, amino resin, epoxy group-containing resin, and tetraisopropoxy titanium.

[0019] The inorganic particles in the pre-coating are silicon dioxide, which are irregular spheres with a particle size of 50-100 nm.

[0020] The antistatic agent in the pre-coating is a cationic quaternary ammonium salt compound;

[0021] The crosslinking agent is selected from one of oxazoline, melamine, carbodiimide, and epoxy compounds.

[0022] The present invention also provides a method for preparing the high-temperature resistant, low-exudation transparent polyester film as described above, characterized by comprising the following steps:

[0023] 1) Casting:

[0024] The process employs a two-layer co-extrusion technique. Polyester chips, antistatic agents, and inorganic particles in the surface layer are melted and extruded, then filtered and introduced into the die orifice. Simultaneously, polyester chips in the core layer are melted and extruded, then filtered and introduced into the die orifice. The two layers are then co-extruded to obtain a molten sheet, which is then cooled by a cold drum to obtain a cast sheet. The surface layer is the surface that adheres to the cold drum.

[0025] 2) Stretching into a film:

[0026] 2-1) Preparation of pre-coating solution:

[0027] The raw material components of the pre-coating layer, namely polyurethane adhesive, curing agent, inorganic particles, crosslinking agent, antistatic agent, and deionized water, are mixed evenly to obtain the pre-coating liquid.

[0028] 2-2) The casting obtained in step 1) is first stretched longitudinally by 2.8-4.0 times, then the pre-coating liquid is applied to the core layer surface, then stretched transversely by 3-5 times, and heat-set to form a pre-coating layer. Finally, after winding, slitting and packaging, the high-temperature resistant, low-exudation transparent polyester film is obtained.

[0029] The beneficial effects of this invention are:

[0030] The transparent polyester film provided by the present invention comprises a surface layer, a core layer and a pre-coating layer stacked in sequence. It has high light transmittance, good high temperature resistance and excellent comprehensive performance, and is particularly suitable for MLCC release film base film, protective film, tape, optical base film and other fields. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0032] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0033] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available. For examples where specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer are followed. For reagents or instruments whose manufacturers are not specified, they are all commercially available products.

[0034] This invention provides a high-temperature resistant, low-emission transparent polyester film, comprising a surface layer, a core layer, and a pre-coating layer stacked sequentially.

[0035] The surface layer, by weight percentage, comprises: 0.5-2.0% inorganic particles, 0.5-2% antistatic agent, and the remainder polyester chips.

[0036] The pre-coating consists of the following components by weight percentage: 25% polyurethane adhesive, 2-8% curing agent, 0.1-1% inorganic particles, 0.005-0.1% crosslinking agent, 0.2-1% antistatic agent, and the remainder is deionized water.

[0037] The core layer is made of polyester chips.

[0038] In a preferred embodiment, the polyester chips in the outer layer and the core layer are selected from one or more of polyethylene terephthalate (PET), polyethylene terephthalate-1,4-cyclohexanediethanol (PETG), polyethylene naphthalate (PEN), and polyethylene terephthalate-1,4-cyclohexanediethanol (PCT).

[0039] More preferably, the polyester chips in the surface layer are PET chips. The viscosity of the polyester chips in the surface layer is 0.70-0.82 dl / g, and the viscosity of the polyester chips in the core layer is 0.62-0.72 dl / g. The viscosity of the core layer is higher than that of the surface layer in order to reduce the precipitation of precipitates from the core layer to the surface, thereby reducing the impact on the haze of the membrane.

[0040] In a preferred embodiment, the inorganic particles in the surface layer and the core layer are selected from one or more of silicon dioxide, calcium carbonate, barium sulfate, and aluminum oxide.

[0041] In a preferred embodiment, the inorganic particles in the surface layer are a mixture of silica and calcium carbonate, with a mass ratio of silica to calcium carbonate of 1:1. The silica consists of irregular spheres with a particle size of 50-200 nm and an average particle size of 100 nm; the calcium carbonate consists of irregular spheres with a particle size of 150-300 nm and an average particle size of 200 nm. Adding silica particles to the surface layer can improve the mechanical properties of the film and also has an anti-adhesion effect, while the addition of calcium carbonate makes the film have better anti-adhesion properties. Too little inorganic particles will not have an anti-adhesion effect, while too many inorganic particles will cause the film to have excessive haze, which is not conducive to subsequent applications. Therefore, the amount of inorganic particles added to the surface layer is 0.5-2.0%.

[0042] In a preferred embodiment, the antistatic agent in the surface layer is selected from cationic, nonionic, anionic, and conductive polymers, and more preferably a cationic quaternary ammonium salt.

[0043] In a preferred embodiment, the curing agent in the pre-coating is one of hydroxyl acrylic resin isocyanate, pyridine, amino resin, epoxy group-containing resin, and tetraisopropoxy titanium; more preferably, it is hydroxyl acrylic resin isocyanate.

[0044] The inorganic particles in the pre-coating are silica, which consists of irregular spheres with a particle size of 50-100 nm and an average particle size of 65 nm. Their function is to improve the film's transmittance. Particles that are too large will scatter light because silica has a very low surface free energy. Particles that are too small will agglomerate, leading to film defects and reduced transmittance. The inorganic particle content in the pre-coating is 0.1-1.0% of the coating liquid weight. Too much content will cause silica agglomeration, while too little content will have no effect on transmittance.

[0045] The antistatic agent in the pre-coating is a cationic quaternary ammonium salt compound; and the content is preferably 0.5% of the weight of the pre-coating liquid. Too much antistatic agent will cause the film surface to fog up, and too little will not play an antistatic role.

[0046] The crosslinking agent is selected from one of oxazoline, melamine, carbodiimide, and epoxy compounds. Epoxy compounds are preferred.

[0047] The preferred pre-coating thickness is 60-100 nm, and more preferably around 80 nm. Within the visible light range, 550 nm is the wavelength the human eye is most sensitive to. According to the principle of destructive interference, a coating thickness of 80 nm is optimal.

[0048] In a preferred embodiment, the total thickness of the high-temperature resistant, low-emission transparent polyester film is preferably 30μm-100μm. If the film is too thin, the mechanical properties will decrease and it will not meet the requirements for optical film applications. If the film is too thick, the light transmittance will decrease.

[0049] In a preferred embodiment, the surface roughness Sa of the pre-coated layer of the present invention is 0.004-0.012 μm, while simultaneously satisfying the maximum height of the surface protrusion Sz ≤ 1 μm; the polyester film is dimensionally stable when used at high temperatures, with the absolute value of the dimensional change rate at 150°C for 2 hours being MD < 1.5% and TD < 0.5%; the light transmittance of the polyester film satisfies T ≥ 90%, haze H ≤ 0.5, and after baking at 150°C for 1 hour, the light transmittance change value is ≤ 0.2%, and the haze change value is ≤ 1.0%.

[0050] The polyester film of the present invention is particularly suitable for use in MLCC release film base film, protective film, tape, optical base film and other fields.

[0051] The present invention also provides a method for preparing the above-mentioned high-temperature resistant, low-exudation transparent polyester film, characterized by comprising the following steps:

[0052] 1) Casting:

[0053] The process employs a two-layer co-extrusion technique. Polyester chips, antistatic agents, and inorganic particles in the surface layer are melted and extruded, then filtered and introduced into the die orifice. Simultaneously, polyester chips in the core layer are melted and extruded, then filtered and introduced into the die orifice. The two layers are then co-extruded to obtain a molten sheet, which is then cooled by a cold drum to obtain a cast sheet. The surface layer is the surface that adheres to the cold drum.

[0054] 2) Stretching into a film:

[0055] 2-1) Preparation of pre-coating solution:

[0056] The raw material components of the pre-coating layer, namely polyurethane adhesive, curing agent, inorganic particles, crosslinking agent, antistatic agent, and deionized water, are mixed evenly to obtain the pre-coating liquid.

[0057] 2-2) The casting obtained in step 1) is first stretched longitudinally by 2.8-4.0 times, then the pre-coating liquid is applied to the core layer surface, and then stretched transversely by 3-5 times and heat-set at 180-240℃ to form a pre-coating layer. Finally, after winding, slitting and packaging, a high-temperature resistant, low-exudation transparent polyester film is obtained.

[0058] The above is the overall concept of the present invention. Detailed embodiments and comparative examples are provided below to further illustrate the present invention.

[0059] In the following examples and comparative examples, the polyester chips in layer A are PET, selected from FG720 produced by Sinopec Yizheng Chemical Fiber; the antistatic agent is a cationic quaternary ammonium salt, selected from SN type antistatic agent produced by Shanghai Tiantan Additives Co., Ltd.

[0060] The B-layer polyester chips are selected from FG600 produced by Sinopec Yizheng Chemical Fiber.

[0061] The polyurethane adhesive for layer C is DF-1307 produced by BASF AG, Germany. The antistatic agent is a cationic quaternary ammonium salt compound, selected from the SN type antistatic agent produced by Shanghai Tiantan Additives Co., Ltd. The crosslinking agent is an epoxy compound, selected from epoxy resin E-44 produced by Sinopec.

[0062] The following examples and comparative examples use the same method for preparing high-temperature resistant, low-exudation transparent polyester films, with the specific steps as follows:

[0063] 1) Casting:

[0064] The process employs a two-layer co-extrusion technique. The surface layer and core layer raw materials are crystallized and dried at 170°C for 4 hours, and then fed into twin-screw and single-screw extruders respectively. After being melt-extruded at 280°C and filtered, they are introduced into the die head. The surface layer and core layer melts are combined in the die head and then flow to a 30°C cooling drum to obtain a 2.0m casting sheet, in which the surface layer is attached to the cooling drum surface.

[0065] 2) Stretching into a film:

[0066] 2-1) Preparation of pre-coating solution:

[0067] The raw material components of the pre-coating layer, namely polyurethane adhesive, curing agent, inorganic particles, crosslinking agent, antistatic agent, and deionized water, are mixed evenly to obtain the pre-coating liquid.

[0068] 2-2) The cast sheet obtained in step 1) is heated to 90°C by a longitudinal preheating roller, stretched longitudinally by 3.7 times, and then the pre-coating liquid is applied to the core layer surface. After stretching transversely by 4.2 times and passing through 5 ovens, each with a temperature set at 220°C, 230°C, 230°C, 200°C and 180°C respectively, a pre-coating layer is formed. Finally, after winding, slitting and packaging, a high-temperature resistant, low-exudation transparent polyester film is obtained.

[0069] The total thickness of the high-temperature resistant, low-emission transparent polyester film is 50μm.

[0070] Example 1

[0071] A high-temperature resistant, low-exudation transparent polyester film, wherein:

[0072] In the surface layer: the PET chips have a viscosity of 0.75 dl / g and a content of 98.5%, an antistatic agent content of 1%, and inorganic particles are silica and calcium carbonate with particle sizes of 100 nm and 200 nm, respectively, in a mass ratio of 1:1. The inorganic particle content of layer A is 0.5%. The above percentages are the mass fractions of layer A by weight.

[0073] In layer B: the viscosity of the polyester chips is 0.65 dl / g, and the content is 100%. The above percentages are the mass fraction of layer B by weight.

[0074] The pre-coating consists of: 25% polyurethane adhesive, 4.0% hydroxyl acrylic resin isocyanate, 0.1% silica particles with a particle size of 65nm, 0.01% crosslinking agent, and 0.5% antistatic agent. The above percentages are the mass fractions of the C-layer coating liquid. Other components in the coating liquid are deionized water, and the pre-coating thickness is 80nm.

[0075] Example 2

[0076] This example is basically the same as Example 1. The main differences are listed below.

[0077] In the surface layer: the viscosity of PET chips is 0.78 dl / g.

[0078] Example 3

[0079] This example is basically the same as Example 1. The main differences are listed below.

[0080] In the surface layer: the viscosity of PET chips is 0.82 dl / g.

[0081] Example 4

[0082] This example is basically the same as Example 2, and the main differences are listed below.

[0083] In the surface layer: the PET chips have a viscosity of 0.78 dl / g and a content of 98.0%, an antistatic agent content of 1%, and inorganic particles are silica and calcium carbonate with particle sizes of 100 nm and 200 nm, respectively, in a mass ratio of 1:1. The inorganic particle content of layer A is 1.0%. The above percentages are the mass fractions of layer A by weight.

[0084] Example 5

[0085] This example is basically the same as Example 2, and the main differences are listed below.

[0086] In the surface layer: the PET chips have a viscosity of 0.78 dl / g and a content of 97.5%, an antistatic agent content of 1%, and inorganic particles are silica and calcium carbonate with particle sizes of 100 nm and 200 nm, respectively, in a mass ratio of 1:1. The inorganic particle content of layer A is 1.5%. The above percentages are the mass fraction of layer A by weight.

[0087] Example 6

[0088] This example is basically the same as Example 2, and the main differences are listed below.

[0089] In the surface layer: the PET chips have a viscosity of 0.78 dl / g and a content of 97.0%, an antistatic agent content of 1%, and inorganic particles are silica and calcium carbonate with particle sizes of 100 nm and 200 nm, respectively, in a mass ratio of 1:1. The inorganic particle content of layer A is 2.0%. The above percentages are the mass fractions of layer A by weight.

[0090] Example 7

[0091] This example is basically the same as Example 5, and the main differences are listed below.

[0092] In layer B: the viscosity of the polyester chips is 0.68 dl / g, and the content is 100%. The above percentages are the mass fraction of layer B by weight.

[0093] Example 8

[0094] This example is basically the same as Example 5, and the main differences are listed below.

[0095] In layer B: the viscosity of the polyester chips is 0.70 dl / g, and the content is 100%. The above percentages are the mass fraction of layer B by weight.

[0096] Example 9

[0097] This example is basically the same as Example 5, and the main differences are listed below.

[0098] In layer B: the viscosity of the polyester chips is 0.72 dl / g, and the content is 100%. The above percentages are the mass fraction of layer B by weight.

[0099] Example 10

[0100] This example is basically the same as Example 8, and the main differences are listed below.

[0101] The pre-coating consists of: 25% polyurethane adhesive, 4.0% hydroxyl acrylic resin isocyanate, 0.4% silica particles with a particle size of 65nm, 0.01% crosslinking agent, and 0.5% antistatic agent. The above percentages are the mass fractions of the C-layer coating liquid. Other components in the coating liquid are deionized water, and the pre-coating thickness is 80nm.

[0102] Example 11

[0103] This example is basically the same as Example 8, and the main differences are listed below.

[0104] The pre-coating consists of: 25% polyurethane adhesive, 4.0% hydroxyl acrylic resin isocyanate, 0.8% silica particles with a particle size of 65nm, 0.01% crosslinking agent, and 0.5% antistatic agent. The above percentages are the mass fractions of the C-layer coating liquid. Other components in the coating liquid are deionized water, and the pre-coating thickness is 80nm.

[0105] Example 12

[0106] This example is basically the same as Example 8, and the main differences are listed below.

[0107] The pre-coating consists of: 25% polyurethane adhesive, 4.0% hydroxyl acrylic resin isocyanate, 1.0% silica particles with a particle size of 65nm, 0.01% crosslinking agent, and 0.5% antistatic agent. The above percentages are the mass fractions of the C-layer coating liquid. Other components in the coating liquid are deionized water, and the pre-coating thickness is 80nm.

[0108] Example 13

[0109] This example is basically the same as Example 11. The main differences are listed below.

[0110] The pre-coating consists of: 25% polyurethane adhesive, 4.0% hydroxyl acrylic resin isocyanate, 0.8% silica particles with a particle size of 65nm, 0.01% crosslinking agent, and 0.5% antistatic agent. The above percentages are the mass fractions of the C-layer coating liquid. Other components in the coating liquid are deionized water, and the pre-coating thickness is 60nm.

[0111] Example 14

[0112] This example is basically the same as Example 11. The main differences are listed below.

[0113] The pre-coating consists of: 25% polyurethane adhesive, 4.0% hydroxyl acrylic resin isocyanate, 0.8% silica particles with a particle size of 65nm, 0.01% crosslinking agent, and 0.5% antistatic agent. The above percentages are the mass fractions of the C-layer coating liquid. Other components in the coating liquid are deionized water, and the pre-coating thickness is 90nm.

[0114] Example 15

[0115] This example is basically the same as Example 11. The main differences are listed below.

[0116] The pre-coating consists of: 25% polyurethane adhesive, 4.0% hydroxyl acrylic resin isocyanate, 0.8% silica particles with a particle size of 65nm, 0.01% crosslinking agent, and 0.5% antistatic agent. The above percentages are the mass fractions of the C-layer coating liquid. Other components in the coating liquid are deionized water, and the pre-coating thickness is 100nm.

[0117] Comparative Example 1

[0118] Stik's G11 three-layer co-extruded film product has a thickness of 50μm, and both the surface and core layers use FG600.

[0119] The following performance tests were performed on the products of Examples 1-15 and Comparative Example 1.

[0120] (1) Surface roughness & maximum height of surface protrusion Sz: According to GB / T 1031-1995 standard, VK-X160K (Keyence) was used to test the surface roughness and maximum height of surface protrusion of the membrane material at 1000X. Five sets of data were taken for each model, and then the average value was taken as Sa & Sz of that model.

[0121] (2) Transmittance & Haze: According to GB / T2410-2008 standard, a lambda950 UV / Vis / NIR spectrophotometer (manufactured by PerkinElmer) was used to test the transmittance and haze under D65 light source conditions using an integrating sphere d / 8° structure. The transmittance and haze data are the weighted average of transmittance at 10nm intervals from 380-780nm, with the weights corresponding to the energy distribution curve of the D65 light source.

[0122] (3) Dimensional change rate: According to GB / T27584-2011 standard, three sets of data were taken for each sample. The sample size was 250mm*250mm in length and MD and TD directions were specified. The samples were placed in a 150℃ oven for 2 hours, then removed and cooled to room temperature before the dimensional change rate was measured. The dimensional change rate was calculated as follows: Dimensional change rate = (L 前 -L 后 ) / L 前*100%, the dimensions before L are the dimensions before testing, and the dimensions after L are the dimensions in the same direction after cooling to room temperature in the oven. Negative values ​​indicate film expansion, and positive values ​​indicate shrinkage.

[0123] (4) Thin film orientation angle: The JAWoollam M-2000 was used for testing. Samples were taken at 5cm intervals in the width direction. The MD direction was used as the reference edge for testing. The software automatically fitted the value and read the orientation angle at 589nm, which is the orientation angle of the sample.

[0124] (5) Pre-coating thickness: JAWoollam M-2000 was used for testing and data fitting was performed. Three groups of samples were tested for each group, and the average value was then calculated as the pre-coating thickness.

[0125] The basic performance test results of the examples and comparative examples are shown in Table 1 below:

[0126] Table 1

[0127]

[0128]

[0129] In summary, the higher the proportion of inorganic particles added, the lower the light transmittance and the greater the haze; the smaller the alignment angle difference, the smaller the performance difference of the film along the TD direction; the smaller the MD / TD dimensional change rate of the film, the more stable the film's dimensions are during use. The test results show that in Examples 1-9, increased addition of surface inorganic particles leads to decreased light transmittance and increased haze; in Examples 10-15, increased addition of pre-coating inorganic particles leads to decreased light transmittance and increased haze; the pre-coating thickness of 60-100 μm has little effect on light transmittance and haze; Examples 1-3 provide optical PET films with good overall performance, with a light transmittance ≥92.3%; among them, Example 2 has the best performance, with a light transmittance of 92.4%, a haze of 0.36%, an absolute value of the alignment angle difference of 4.5°, a coating thickness of 80 nm, a dimensional change rate of 1.20 / 0.32, a surface roughness of 0.004 μm, and a maximum protrusion height of 0.4 μm.

[0130] The overall performance of Examples 1-15 is better than that of Comparative Example 1.

[0131] High-Temperature Low-Deposition Optical Polyester Film Performance Testing

[0132] Take the film samples from Examples 1-15 and Comparative Example 1, and take 10 film samples at equal intervals across the full width. Cut them into A4 paper sizes and measure their optical properties. Then place the samples in a 150°C constant temperature oven for 1 hour. After cooling, measure their optical properties. The change in optical properties before and after high temperature treatment can reflect the film's resistance to 150°C high temperature and low precipitation.

[0133] The test results of high-temperature, low-precipitation optical performance are shown in Table 2 below:

[0134] Table 2

[0135]

[0136] Note: T / %: transmittance; △T / %: transmittance change.

[0137] H / %: Haze; △H / %: Haze change value.

[0138] In summary, the viscosity of the raw material has a certain impact on high temperature and low precipitation. The main difference is that the greater the viscosity difference of the raw material on the new surface, the better the high temperature and low precipitation performance.

[0139] The high-temperature, low-precipitation performance of Examples 1-15 is superior to that of Comparative Example 1.

[0140] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A high-temperature resistant, low-emission transparent polyester film, characterized in that, It includes a surface layer, a core layer, and a pre-coating layer stacked sequentially: The raw material components of the surface layer are inorganic particles, polyester chips, and antistatic agent; The raw material component of the core layer is polyester chips; The raw material components of the pre-coating are polyurethane adhesive, curing agent, inorganic particles, crosslinking agent, antistatic agent and deionized water; The specific components of the raw materials in the surface layer, by weight percentage, are as follows: Inorganic particles 0.5-2.0%, antistatic agent 0.5-2%, the remainder is polyester chips; The inorganic particles in the surface layer are a mixture of silicon dioxide and calcium carbonate, and the mass ratio of silicon dioxide to calcium carbonate is 1:

1. The silica consists of irregular spheres with a particle size of 50-200 nm, and the calcium carbonate consists of irregular spheres with a particle size of 150-300 nm. The curing agent in the pre-coating is one of hydroxyl acrylic resin isocyanate and amino resin; The inorganic particles in the pre-coating are silicon dioxide, which are irregular spheres with a particle size of 50-100 nm. The antistatic agent in the pre-coating is a cationic quaternary ammonium salt compound; The crosslinking agent is selected from one of oxazoline, melamine, carbodiimide, and epoxy compounds; The viscosity of the polyester chips in the surface layer is 0.70-0.82 dl / g, and the viscosity of the polyester chips in the core layer is 0.62-0.72 dl / g.

2. The high-temperature resistant, low-emission transparent polyester film according to claim 1, characterized in that, The pre-coating consists of the following raw material components by weight percentage: The composition consists of 25% polyurethane adhesive, 2-8% curing agent, 0.1-1% inorganic particles, 0.005-0.1% crosslinking agent, 0.2-1% antistatic agent, and the remainder is deionized water.

3. The high-temperature resistant, low-emission transparent polyester film according to claim 1, characterized in that, The polyester chips in the outer and core layers are selected from one or more of polyethylene terephthalate, polyethylene terephthalate-1,4-cyclohexanediethanol, polyethylene naphthalate, and polyethylene terephthalate-1,4-cyclohexanediethanol.

4. The high-temperature resistant, low-emission transparent polyester film according to claim 1, characterized in that, The antistatic agent in the surface layer is selected from cationic, nonionic, anionic, and conductive polymers.

5. A method for preparing a high-temperature resistant, low-exudation transparent polyester film as described in any one of claims 1-4, characterized in that, Includes the following steps: 1) Casting: The process employs a two-layer co-extrusion technique. Polyester chips, antistatic agents, and inorganic particles in the surface layer are melted and extruded, then filtered and introduced into the die orifice. Simultaneously, polyester chips in the core layer are melted and extruded, then filtered and introduced into the die orifice. The two layers are then co-extruded to obtain a molten sheet, which is then cooled by a cold drum to obtain a cast sheet. The surface layer is the surface that adheres to the cold drum. 2) Stretching into a film: 2-1) Preparation of pre-coating solution: The raw material components of the pre-coating layer, namely polyurethane adhesive, curing agent, inorganic particles, crosslinking agent, antistatic agent, and deionized water, are mixed evenly to obtain the pre-coating liquid. 2-2) The casting obtained in step 1) is first stretched longitudinally by 2.8-4.0 times, then the pre-coating liquid is applied to the core layer surface, then stretched transversely by 3-5 times, and heat-set to form a pre-coating layer. Finally, after winding, slitting and packaging, the high-temperature resistant, low-exudation transparent polyester film is obtained.

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