Polyester film and preparation method thereof

Abstract

The invention relates to the technical field of films, and provides a polyester film and a preparation method thereof. The preparation method comprises the following steps: S100, mixing an aerogel solution with a polyester copolymer, and stirring to obtain a first mixture; s200, coating a plane base material with the first mixture through a casting machine, and carrying out drying treatment to form a thin film; and S300, carrying out longitudinal stretching and transverse stretching on the film, and carrying out heat treatment to completely cure the film, so as to obtain the polyester film. By introducing aerogel into the film and forming a porous structure, sound can be effectively absorbed and isolated, so that the sound insulation effect of the film is enhanced, meanwhile, the weight of the film is greatly reduced due to the lightweight characteristic of aerogel, the strength and toughness of the polyester film are kept, and finally, by utilizing the low heat conductivity of aerogel, the sound insulation effect of the film is improved. The heat insulation performance of the film is obviously improved; therefore, the defects of a traditional polyester film in the aspects of sound insulation, light weight, heat insulation and the like are overcome, and finally a film material with higher performance is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of films, and in particular to a polyester film and a preparation method thereof. Background Art

[0002] With the continuous development of science and technology, polyester film, as a common high-performance material, is widely used in packaging, electronics, optics, energy, construction and other fields. Traditional polyester film has excellent mechanical strength, transparency and chemical corrosion resistance, but in some specific applications, especially those that require excellent heat insulation, sound insulation and light weight, the existing polyester film is insufficient and cannot meet the needs of high-performance applications.

[0003] In order to solve these shortcomings of traditional polyester films, how to give polyester films better sound insulation, lightness and heat insulation has become a problem that current scholars urgently need to tackle. Summary of the invention

[0004] Therefore, the present invention provides a polyester film and a preparation method thereof. By introducing aerogel into the film and forming a porous structure, the sound can be effectively absorbed and isolated, thereby enhancing the sound insulation effect of the film. At the same time, the lightweight characteristics of the aerogel greatly reduce the weight of the film while maintaining the strength and toughness of the polyester film. Finally, the low thermal conductivity of the aerogel is utilized to significantly improve the thermal insulation performance of the film; thereby overcoming the deficiencies of traditional polyester films in sound insulation, lightness and thermal insulation, and ultimately achieving a higher performance film material.

[0005] To solve the above problems, the first object of the present invention is to provide a method for preparing a polyester film;

[0006] The second object of the present invention is to provide a polyester film;

[0007] To achieve the first objective of the present invention, the present invention provides a method for preparing a polyester film, which comprises the following steps: S100, mixing reaction: mixing an aerogel solution with a polyester copolymer, stirring to obtain a first mixture; S200, film forming: coating the first mixture on a flat substrate through a casting machine, drying to form a film; S300, stretching and curing the film: stretching the film longitudinally and transversely, and performing heat treatment to completely cure the film, thereby obtaining a polyester film.

[0008] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: by introducing aerogel into the polyester film, aerogel, as a material with high specific surface area and porous structure, has good thermal insulation properties, and can effectively prevent heat conduction without significantly increasing the thickness of the film, thereby improving the thermal insulation performance of the film, and the porous structure has good sound wave absorption and isolation functions, which can effectively improve the sound insulation performance of the film and reduce noise transmission; the stretching and curing process of the polyester film after heat treatment can effectively improve its tensile strength and tear resistance. After longitudinal and transverse stretching, the molecular structure of the film is more uniform, and the tensile properties are significantly improved, which is suitable for applications requiring the film to have strong tensile resistance and durability; and the combination of aerogel and polyester copolymer in the present invention can take into account both high transparency and high thermal insulation performance, and is suitable for various application scenarios requiring transparency and thermal insulation; through the process of coating by casting process and heat treatment curing, the polyester film not only obtains excellent thermal insulation effect, but also has better environmental adaptability, is not easy to age and fail, and extends the service life of the film; finally, the preparation method uses a casting machine to form the film, and completes the preparation of the film through simple stretching and curing steps. The process is simple and efficient, adapts to mass production needs, and has a relatively low production cost, which is suitable for commercial applications.

[0009] In a technical solution of the present invention, in step S100, the preparation method of the polyester copolymer adopts the following steps: S101, the polyester monomer and the comonomer are mixed and dissolved in a first solvent, a catalyst is added, and the polyester monomer is subjected to a condensation reaction by heating, and then cooled and filtered to obtain a polyester copolymer.

[0010] Compared with the prior art, the technical effect achieved by the technical solution is as follows: by mixing polyester monomers with comonomers and heating to initiate a polycondensation reaction, a polyester copolymer with specific properties can be synthesized; by selecting different comonomers (such as fluorine-containing monomers, acrylic monomers, etc.), different functional groups can be introduced into the polyester molecular chain to improve the properties of the film, so that the final polyester film not only has the advantages of traditional polyester materials, but also can show better performance in special environments or applications, such as better weather resistance, UV resistance and oxidation resistance; by heating and the action of a catalyst, the polyester monomer is induced to undergo a polycondensation reaction, and unreacted monomers or impurities are removed by cooling and filtering, thereby obtaining a high-purity polyester copolymer. This process not only improves the reactivity of the polyester copolymer, but also ensures the stability and consistency of the product, and avoids performance fluctuations caused by impurities or impure substances; by-products and unreacted products that may be generated during the reaction are removed by appropriate filtering steps, ensuring that the final polyester copolymer has high purity and uniform molecular structure, which can ensure good film structure and uniformity during film molding, thereby improving the strength, transparency and durability of the film, and ensuring the high performance of the film in practical applications.

[0011] In one technical solution of the present invention, in step S101, the comonomer includes at least one of a fluorine-containing monomer, an acrylic monomer, and an amino acid monomer; and / or the polyester monomer includes at least one of terephthalic acid and ethylene glycol; and / or the first solvent includes xylene; and / or the catalyst includes titanium tetrachloride; and / or the mass ratio of the polyester monomer to the comonomer is approximately (4-9):1; and / or the temperature of the heating treatment is between 170°C and 230°C.

[0012] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: through the selection of these copolymer monomers, the characteristics of the film can be customized according to the specific application requirements, so that it has stronger UV resistance, corrosion resistance, water resistance or oxidation resistance. Fluorine-containing monomers enhance the chemical corrosion resistance, high temperature resistance and UV resistance of the film; acrylic monomers improve the water resistance, flexibility and processing performance of the film; amino acid monomers provide good biodegradability and stronger hydrophilicity;

[0013] Terephthalic acid and ethylene glycol are the basic raw materials for preparing polyester copolymers. They form polyester chains through polycondensation reactions, providing a structural basis for the film. Terephthalic acid increases the thermal stability and rigidity of the film; ethylene glycol increases the flexibility and transparency of the film.

[0014] Xylene as a solvent can effectively dissolve polyester monomers and comonomers and promote the reaction. Xylene has low volatility and good solubility, and is suitable for the synthesis of polyester copolymers. It can ensure the uniformity of the reaction system, avoid incomplete dissolution or incomplete reaction of the polyester copolymer caused by poor solvent, and ensure the stability of the quality of the final polyester copolymer.

[0015] Titanium tetrachloride, as a catalyst, can effectively accelerate the polycondensation reaction of polyester monomers and comonomers. By adding the catalyst, the reaction efficiency can be improved, the reaction time can be shortened, a polyester copolymer with a large molecular weight can be obtained, and the mechanical strength, durability and thermal stability of the polyester film can be improved;

[0016] The mass ratio of polyester monomer to comonomer affects the molecular structure and properties of polyester copolymers. A higher polyester monomer ratio helps to improve the strength and durability of the film, while a higher comonomer ratio helps to adjust the flexibility and functionality of the film. By adjusting the mass ratio of polyester monomer to comonomer, the structure and properties of polyester copolymers can be precisely controlled so that they can meet the strength requirements and have the required special functions (such as UV resistance, water resistance, etc.);

[0017] The heating treatment temperature directly affects the condensation reaction rate of the polyester copolymer and the molecular weight of the product. A higher temperature helps to accelerate the reaction process and increase the degree of polymerization, but too high a temperature may lead to side reactions. The temperature is controlled within the range of 170-230°C to ensure the increase of the degree of polymerization during the synthesis of the polyester copolymer and obtain a suitable molecular weight, thereby making the film perform better in terms of mechanical properties, thermal stability and transparency.

[0018] In a technical solution of the present invention, in step S100, the preparation method of the aerogel solution adopts the following steps: S111, adding a silicon source to an alcohol solvent, and then adding water and a catalyst to carry out hydrolysis reaction and polycondensation reaction, and forming a gel solution after standing for a certain period of time; S112, soaking the gel solution in a displacement solvent, and after the displacement solvent completely penetrates the gel, drying it to obtain an aerogel solution.

[0019] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: adding a silicon source to an alcohol solvent, and then adding water and a catalyst to carry out hydrolysis and polycondensation reactions. In the hydrolysis reaction, the ethoxy group in the silicon source reacts with water to generate silanol; in the subsequent polycondensation reaction, the silanol molecules form silicon-oxygen bonds through condensation reactions, and gradually build up the network structure of the aerogel; through this process, the silicon source is converted into a gel solution with a three-dimensional structure, which is a precursor of the aerogel, has a high specific surface area and low density, and lays the foundation for the subsequent solvent replacement and drying steps; after the gel solution is formed, it is necessary to The alcohol solvent used in the reaction is removed by solvent replacement, usually with a more polar solvent, and the gel solution is immersed in the new solvent to ensure the final purity of the aerogel, ensure that the original solvent is completely replaced, and avoid the influence of residual solvent on the properties of the aerogel; after the replacement process is completed, the gel enters the drying stage. The drying treatment removes the solvent and retains the porous structure of the aerogel, giving it excellent thermal insulation, low density and high specific surface area. Characteristics ensure that the aerogel solution can be effectively added to the polyester film to improve the film's thermal insulation, sound insulation, lightweight and other properties.

[0020] In a technical solution of the present invention, in step S111, the catalyst includes at least one of hydrochloric acid and ammonia water; and / or the alcohol solvent includes at least one of methanol and n-butanol; and / or the silicon source includes at least one of tetraethoxysilane and tetraethyl orthosilicate; and / or the ratio of the silicon source, the alcohol solvent and water is 1:(4-6):(2-4); and / or the pH value of the hydrolysis reaction is in the range of 1-3; and / or the pH value of the condensation reaction is in the range of 5-7.

[0021] Compared with the prior art, the technical effect achieved by adopting the technical solution is as follows: in step S111, the selection of catalyst, solvent, silicon source and the setting of reaction conditions play a vital role in the formation of aerogel solution and the final effect of aerogel performance; the catalyst is used to promote the hydrolysis and polycondensation reactions. By selecting a suitable acidic or alkaline catalyst, the rate and efficiency of the hydrolysis and polycondensation reactions can be optimized at different reaction stages, thereby controlling the structure and performance of the aerogel. Hydrochloric acid is used to promote hydrolysis, and ammonia water is used to promote polycondensation, which helps to form a more stable three-dimensional silicon-oxygen network;

[0022] Alcohol solvents are used to dissolve silicon sources and promote hydrolysis reactions during the synthesis of aerogels. By selecting different alcohol solvents, the pore structure, specific surface area, and viscosity of the gel solution of the aerogel can be controlled. Methanol can accelerate the reaction, while n-butanol helps to adjust the structural properties of the aerogel.

[0023] Silicon source is the key component of aerogel synthesis and determines the basic structure of aerogel. By selecting a suitable silicon source, the pore structure, specific surface area and final thermal conductivity and sound insulation performance of aerogel can be adjusted. Tetraethoxysilane provides high reactivity, allowing aerogel to quickly form a stable network structure.

[0024] The ratio of silicon source, alcohol solvent and water is a key parameter in aerogel synthesis, which directly affects the rate of hydrolysis and polycondensation reaction, the formation of gel and the structural characteristics of the final aerogel. Controlling the ratio of water to silicon source in the reaction helps to adjust the rate and balance of hydrolysis and polycondensation reaction, thereby controlling the formation rate and pore structure of aerogel, and also avoids uneven aerogel structure or unstable performance caused by too fast or too slow reaction.

[0025] By controlling the pH value of the hydrolysis reaction within the range of 1-3, it is possible to ensure that the silicon source is completely hydrolyzed and the reaction rate is moderate, thereby obtaining a high-quality gel solution. Too high a pH value may cause the hydrolysis reaction to be too intense, resulting in an uneven gel.

[0026] A neutral environment facilitates the polycondensation reaction between silanols and promotes the formation of silicon-oxygen bonds, thereby constructing the three-dimensional network structure of the aerogel. A neutral pH can avoid the influence of excessively acidic or alkaline conditions on the aerogel structure, ensuring its uniformity and stability.

[0027] In a technical solution of the present invention, in step S112, the replacement solvent includes at least one of ethanol and propanol; and / or the drying process includes any one of supercritical drying or atmospheric pressure drying.

[0028] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: in step S112, the replacement solvent is used to replace the original solvent, helping to remove the residual solvent in the reaction process, ensuring the purity of the aerogel, and improving the pore structure of the aerogel so that its specific surface area and porosity reach the optimal state. Using ethanol or propanol as the replacement solvent can more effectively remove the original solvent while avoiding any organic solvent residue that may affect the performance of the aerogel;

[0029] Drying is a key step in removing solvents and completing the aerogel formation process. The supercritical drying method can maximize the preservation of the original porous structure of the aerogel, avoid pore collapse, and ensure its excellent thermal insulation and lightness properties. Drying at normal pressure is simpler and more economical.

[0030] In a technical solution of the present invention, in step S200, the coating thickness is between 10-100 μm; and / or the coating speed of the casting machine is between 5-20 m / min; and / or the drying temperature is between 40-60° C. and the time is between 10-30 minutes.

[0031] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: in step S200, the coating thickness, the coating speed of the casting machine, and the temperature and time of the drying process can affect the uniformity and quality of the polyester film;

[0032] By controlling the coating thickness, the properties of the film can be balanced to ensure its optimal effect in a specific application. The appropriate thickness can achieve better comprehensive properties such as mechanical strength, thermal isolation and audio isolation while maintaining a low weight.

[0033] The coating speed of the cast film machine directly affects the uniformity and quality of the film during the coating process. A higher coating speed can improve production efficiency, but may lead to uneven coating or inconsistent thickness. Although a lower coating speed can improve coating uniformity, it will affect production efficiency. By reasonably selecting the coating speed, production efficiency can be improved while ensuring film uniformity, avoiding performance fluctuations caused by uneven coating.

[0034] The temperature and time of the drying process have an important impact on the quality and final performance of the film. Too high a temperature or too long a time may cause deformation or thermal damage to the film, while too low a temperature or too short a time may result in incomplete removal of moisture from the film, affecting the structural stability of the film. By properly selecting the drying temperature and time, the residual solvent in the coating process can be effectively removed to ensure the stability and uniformity of the film. At the same time, it can also avoid structural damage to the polyester film caused by too high a drying temperature or too long a drying time.

[0035] In one technical solution of the present invention, in step S300, the temperature of longitudinal stretching is between 80-95°C, and the stretching rate is between 600-800 mm / min; and / or the temperature of transverse stretching is between 90-120°C, and the stretching rate is 700-1000 mm / min; and / or the temperature of heat treatment is between 120-160°C.

[0036] Compared with the prior art, the technical effects achieved by adopting this technical solution are as follows: longitudinal stretching is a key step in the film production process. The film is stretched to improve its mechanical properties and enhance its strength and toughness. At this stage, the molecular chains of the film will be stretched in the longitudinal direction to increase the longitudinal strength and rigidity of the film. The lower stretching temperature can avoid thermal damage to the film, but it is still sufficient to make the molecular chains flow and rearrange, thereby enhancing the mechanical properties of the film. Within this temperature range, the film has sufficient ductility and will not deform excessively. A moderate stretching rate helps to form a uniform molecular orientation, avoiding film rupture due to excessive stretching, or uneven stretching due to excessive stretching. This rate helps to maintain the quality of the film while ensuring production efficiency. By controlling the temperature and rate of longitudinal stretching, the longitudinal strength, toughness and durability of the film can be effectively improved, while avoiding deformation or performance degradation of the film due to excessive stretching.

[0037] Transverse stretching helps to improve the transverse strength and dimensional stability of the film. The film will be stretched in the transverse direction, so that the molecular chains are more orderly arranged in the transverse direction, thereby improving the strength and tear resistance of the film; higher stretching temperature can improve the flexibility of polyester film and reduce cracks and fractures during stretching. This temperature range helps to enhance the ductility of the film in the transverse direction, making the film less prone to brittle fracture during transverse stretching; moderate transverse stretching rate ensures that the film can be stretched evenly to avoid uneven stretching or internal stress. Too fast a stretching rate may cause uneven film stretching, while too slow a stretching rate will affect production efficiency; by optimizing the temperature and rate of transverse stretching, a more uniform transverse strength can be obtained, the tear resistance and durability of the film can be improved, and the stability and durability of the film in actual use can be ensured.

[0038] Heat treatment is a key step to ensure that the film is fully cured, remove residual stress and further improve the film performance. By heating at high temperature, the arrangement and crystallization of the polyester molecular chains will further enhance the mechanical properties and thermal stability of the film; the temperature at 120-160°C helps promote the crystallization process of the polyester film, improve its dimensional stability and heat resistance, and the appropriate heat treatment temperature can make the molecular structure of the polyester film more orderly, further improving its mechanical strength, thermal stability and aging resistance.

[0039] In a technical solution of the present invention, after step S300, the method further includes: S400, surface treatment of the membrane: coating a polytetrafluoroethylene coating on the surface of the polyester film.

[0040] Compared with the existing technology, the technical effect achieved by adopting this technical solution is: by coating the surface of the polyester film with a polytetrafluoroethylene coating, not only can the chemical resistance, high temperature resistance, water resistance, anti-stickiness and wear resistance of the film be significantly enhanced, but also its sliding performance and appearance gloss can be improved. These improvements make the application field of polyester film more extensive.

[0041] To achieve the second purpose of the present invention, the present invention provides a polyester film, which is prepared by a preparation method as described in any one of the above-mentioned technical solutions. Therefore, the polyester film of the present invention has all the beneficial effects of the preparation method of the polyester film as described in any one of the technical solutions of the present invention, which will not be repeated here.

[0042] After adopting the technical solution of the present invention, the following technical effects can be achieved:

[0043] (1) The porous aerogel introduced into the film can effectively absorb and isolate sound waves, thereby significantly improving the sound insulation effect. In addition, the low thermal conductivity of aerogel can greatly improve the thermal insulation effect of the film, overcoming the shortcomings of traditional polyester film in sound insulation and heat insulation. Finally, the lightweight characteristics of aerogel keep the film at a low weight, and the stretching and heat treatment process of the film significantly enhances its tensile strength and durability. It is suitable for application scenarios with high requirements for strength and toughness, especially in occasions where the film needs to be lightweight.

[0044] (2) By improving the molecular structure, the tensile strength, tear resistance and wear resistance of the modified polyester film have been improved, making it suitable for applications requiring high durability, such as electronic and electrical protective films or industrial films;

[0045] (3) Through surface coating technology, polyester film can obtain different surface properties, further broadening its application range. DETAILED DESCRIPTION

[0046] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In order to solve the shortcomings of traditional polyester films in the fields of heat insulation, sound insulation and lightweight properties, the present embodiment provides a polyester film and a preparation method thereof. By introducing aerogel into the film and forming a porous structure, the sound can be effectively absorbed and isolated, thereby enhancing the sound insulation effect of the film. At the same time, the lightweight properties of the aerogel greatly reduce the weight of the film while maintaining the strength and toughness of the polyester film. Finally, the low thermal conductivity of the aerogel is utilized to significantly improve the thermal insulation performance of the film; thereby overcoming the shortcomings of traditional polyester films in sound insulation, lightness and heat insulation, and ultimately achieving a higher performance film material.

[0048] The method for preparing the polyester film of this embodiment comprises the following steps:

[0049] S100, mixing reaction: mixing the aerogel solution and the polyester copolymer, and stirring to obtain a first mixture;

[0050] The preparation method of the polyester copolymer comprises the following steps:

[0051] S101, mixing the polyester monomer and the comonomer, dissolving them in a first solvent, adding a catalyst, heating the polyester monomer to cause a polycondensation reaction, cooling and filtering the mixture, and obtaining a polyester copolymer.

[0052] Preferably, the comonomer includes at least one of a fluorine-containing monomer, an acrylic monomer, and an amino acid monomer. By selecting these comonomers, the properties of the film can be customized according to specific application requirements so that it has stronger UV resistance, corrosion resistance, water resistance or oxidation resistance. The fluorine-containing monomer enhances the film's chemical corrosion resistance, high temperature resistance and UV resistance; the acrylic monomer improves the film's water resistance, flexibility and processing properties; the amino acid monomer provides good biodegradability and stronger hydrophilicity.

[0053] The polyester monomer includes at least one of terephthalic acid and ethylene glycol; terephthalic acid and ethylene glycol are the basic raw materials for preparing polyester copolymers, and polyester chains are generated through condensation reactions to provide a structural basis for the film. Terephthalic acid increases the thermal stability and rigidity of the film; ethylene glycol increases the flexibility and transparency of the film.

[0054] The first solvent includes xylene. Xylene as a solvent can effectively dissolve polyester monomers and comonomers and promote the reaction. Xylene has low volatility and good solubility, and is suitable for the synthesis of polyester copolymers. It can ensure the uniformity of the reaction system and avoid incomplete dissolution or incomplete reaction of the polyester copolymer due to poor solvent, thereby ensuring the stable quality of the final polyester copolymer.

[0055] Catalysts include titanium tetrachloride, which can effectively accelerate the condensation reaction of polyester monomers and comonomers. The addition of catalysts can improve reaction efficiency, shorten reaction time, obtain polyester copolymers with larger molecular weight, and improve the mechanical strength, durability and thermal stability of polyester films.

[0056] The mass ratio of polyester monomer to comonomer is approximately (4-9):1. The mass ratio of polyester monomer to comonomer affects the molecular structure and properties of polyester copolymers. A higher polyester monomer ratio helps to improve the strength and durability of the film, while a higher comonomer ratio helps to adjust the flexibility and functionality of the film. By adjusting the mass ratio of polyester monomer to comonomer, the structure and properties of polyester copolymers can be precisely controlled so that they can meet the strength requirements and have the required special functions (such as UV resistance, water resistance, etc.).

[0057] The heating treatment temperature is 170-230°C. The heating treatment temperature directly affects the condensation reaction rate of the polyester copolymer and the molecular weight of the product. A higher temperature helps to accelerate the reaction process and increase the degree of polymerization, but too high a temperature may lead to side reactions. The temperature is controlled within the range of 170-230°C to ensure the increase in the degree of polymerization during the synthesis of the polyester copolymer and obtain a suitable molecular weight, thereby making the film perform better in terms of mechanical properties, thermal stability and transparency.

[0058] Furthermore, polyester copolymers with specific properties can be synthesized by mixing polyester monomers with comonomers and heating to initiate polycondensation reactions. By selecting different comonomers (such as fluorine-containing monomers, acrylic monomers, etc.), different functional groups can be introduced into the polyester molecular chain to improve the properties of the film, so that the final polyester film not only has the advantages of traditional polyester materials, but also exhibits better performance in special environments or applications, such as better weather resistance, UV resistance and oxidation resistance. By heating and the action of catalysts, the polyester monomers are induced to undergo polycondensation reactions, and unreacted monomers or impurities are removed by cooling and filtering, thereby obtaining high-purity polyester copolymers. This process not only improves the reactivity of the polyester copolymer, but also ensures the stability and consistency of the product, and avoids performance fluctuations caused by impurities or impure substances. Appropriate filtration steps are used to remove byproducts and unreacted products that may be generated during the reaction, ensuring that the final polyester copolymer has high purity and uniform molecular structure, which can ensure good film structure and uniformity during film molding, thereby improving the strength, transparency and durability of the film, and ensuring high performance of the film in practical applications.

[0059] In addition, the preparation method of the aerogel solution adopts the following steps:

[0060] S111, adding a silicon source to an alcohol solvent, and then adding water and a catalyst to carry out a hydrolysis reaction and a polycondensation reaction, and forming a gel solution after standing for a certain period of time;

[0061] Preferably, the catalyst includes at least one of hydrochloric acid and ammonia water. The catalyst is used to promote the hydrolysis and polycondensation reactions. By selecting a suitable acidic or alkaline catalyst, the rate and efficiency of the hydrolysis and polycondensation reactions can be optimized at different reaction stages, thereby controlling the structure and performance of the aerogel. Hydrochloric acid is used to promote hydrolysis, and ammonia water is used to promote polycondensation, which helps to form a more stable three-dimensional silicon-oxygen network. Hydrochloric acid, as an acidic catalyst, can accelerate the hydrolysis reaction, help the ethoxy group in the silicon source react with water to form silanol, and hydrochloric acid can provide an acidic environment, reduce the energy barrier of the hydrolysis reaction, and promote the hydrolysis process of the silicon source. Ammonia water, as an alkaline catalyst, can increase the rate of the polycondensation reaction. Ammonia water provides alkaline conditions in the reaction, helps the silanol molecules to form silicon-oxygen bonds through condensation reactions, and accelerates the formation of the network structure of the aerogel.

[0062] The alcohol solvent includes at least one of methanol and n-butanol. The alcohol solvent is used to dissolve the silicon source and promote the hydrolysis reaction during the synthesis of the aerogel. By selecting different alcohol solvents, the pore structure, specific surface area and viscosity of the aerogel solution can be controlled. Methanol can accelerate the reaction, while n-butanol helps to adjust the structural characteristics of the aerogel. Due to its smaller molecular structure and higher polarity, methanol can better dissolve the silicon source and can effectively react with water and catalysts to help accelerate hydrolysis and condensation reactions. n-butanol has larger molecules than methanol and lower polarity, so its solubility is slightly worse, and it is suitable for preparing gel solutions with higher viscosity, and can adjust the pore structure of the aerogel and affect the specific surface area of ​​the final product.

[0063] The silicon source includes at least one of tetraethoxysilane and tetraethyl orthosilicate. The silicon source is a key component for the synthesis of aerogel and determines the basic structure of aerogel. By selecting a suitable silicon source, the pore structure, specific surface area and final thermal conductivity and sound insulation performance of the aerogel can be adjusted. Tetraethoxysilane provides higher reactivity, allowing the aerogel to quickly form a stable network structure; tetraethoxysilane is a common silicon source with high reactivity. It can quickly undergo hydrolysis reaction to generate silanols, and further form silicon oxygen bonds (Si-O-Si) through condensation reaction, thereby constructing a three-dimensional network structure of aerogel; tetraethyl orthosilicate is also a commonly used silicon source, and its reaction properties are similar to those of tetraethoxysilane.

[0064] The ratio of silicon source, alcohol solvent and water is 1:(4-6):(2-4). The ratio of silicon source, alcohol solvent and water is a key parameter in aerogel synthesis, which directly affects the rate of hydrolysis and polycondensation reaction, the formation of gel and the structural characteristics of the final aerogel. Controlling the ratio of water to silicon source in the reaction helps to adjust the rate and balance of hydrolysis and polycondensation reaction, thereby controlling the formation rate and pore structure of aerogel, and also avoids uneven aerogel structure or unstable performance caused by too fast or too slow reaction.

[0065] By controlling the pH value of the hydrolysis reaction within the range of 1-3, it is possible to ensure that the silicon source is completely hydrolyzed and the reaction rate is moderate, thereby obtaining a high-quality gel solution. Too high a pH value may cause the hydrolysis reaction to be too intense, resulting in an uneven gel.

[0066] A neutral environment facilitates the polycondensation reaction between silanols and promotes the formation of silicon-oxygen bonds, thereby constructing the three-dimensional network structure of the aerogel. A neutral pH can avoid the influence of excessively acidic or alkaline conditions on the aerogel structure, ensuring its uniformity and stability.

[0067] Furthermore, a silicon source is added to an alcohol solvent, and then water and a catalyst are added to carry out hydrolysis and polycondensation reactions. In the hydrolysis reaction, the ethoxy group in the silicon source reacts with water to generate silanol. In the subsequent polycondensation reaction, the silanol molecules form silicon-oxygen bonds through condensation reactions, and gradually build up the network structure of the aerogel. Through this process, the silicon source is converted into a gel solution with a three-dimensional structure, which is a precursor of aerogel, has a high specific surface area and low density, and lays the foundation for the subsequent solvent replacement and drying steps. After the gel solution is formed, it is necessary to remove the alcohol solvent used in the reaction through solvent replacement, usually using a more polar solvent for replacement, and soaking the gel solution in a new solvent to ensure the final purity of the aerogel, ensure that the original solvent is completely replaced, and avoid the influence of residual solvent on the properties of the aerogel. After the replacement process is completed, the gel enters the drying stage, and the drying process removes the solvent and retains the porous structure of the aerogel, so that it has excellent thermal insulation, low density and high specific surface area, etc., ensuring that the aerogel solution can be effectively added to the polyester film to improve the thermal insulation, sound insulation, lightness and other properties of the film.

[0068] S112, soaking the gel solution in a displacement solvent, and drying the gel after the displacement solvent completely permeates the gel to obtain an aerogel solution.

[0069] Preferably, the replacement solvent includes at least one of ethanol and propanol. The replacement solvent is used to replace the original solvent, help remove the residual solvent in the reaction process, ensure the purity of the aerogel, and improve the pore structure of the aerogel so that its specific surface area and porosity reach the optimal state. Using ethanol or propanol as the replacement solvent can more effectively remove the original solvent while avoiding any organic solvent residue that may affect the performance of the aerogel; ethanol is a common solvent with high polarity, which can effectively dissolve and clean impurities in the solvent. Ethanol has a strong affinity with water and alcohol solvents, which helps to completely replace the original solvent during the replacement process; propanol has a larger molecule than ethanol and has a slightly lower polarity, and is often used to adjust the porosity and specific surface area of ​​the aerogel. It can control the pore structure and macroscopic morphology of the aerogel to a certain extent during the formation of the aerogel.

[0070] Drying treatment includes either supercritical drying or atmospheric pressure drying. Drying treatment is a key step in removing solvents and completing the aerogel formation process. The supercritical drying method can maximize the maintenance of the original porous structure of the aerogel, avoid the collapse of pores, and ensure its excellent thermal insulation and lightness. Atmospheric pressure drying is simpler and more economical. Supercritical drying is a drying process carried out under a supercritical state. Supercritical carbon dioxide is usually used as a drying medium. Since supercritical carbon dioxide has a lower surface tension, it can effectively remove the solvent while effectively retaining the high specific surface area and porous structure of the aerogel without destroying the pore structure of the aerogel, avoiding pore shrinkage or structural collapse caused by solvent evaporation during conventional drying. Supercritical drying can obtain higher quality and more uniform aerogels than conventional drying methods. It is carried out at room temperature, using air or hot air to evaporate the solvent in the aerogel, and the cost of atmospheric pressure drying is lower.

[0071] S200, film forming: coating the first mixture on a flat substrate through a casting machine, and forming a film after drying;

[0072] Preferably, by controlling the coating thickness, the properties of the film can be balanced to ensure its best effect in a specific application, and a moderate thickness can achieve better comprehensive properties, such as mechanical strength, thermal isolation and audio isolation performance, while maintaining a low weight.

[0073] The coating speed of the cast film machine directly affects the uniformity and quality of the film during the coating process. A higher coating speed can improve production efficiency, but may lead to uneven coating or inconsistent thickness. Although a lower coating speed can improve coating uniformity, it will affect production efficiency. By reasonably selecting the coating speed, production efficiency can be improved while ensuring film uniformity, avoiding performance fluctuations caused by uneven coating.

[0074] The temperature and time of the drying process have an important impact on the quality and final performance of the film. Too high a temperature or too long a time may cause deformation or thermal damage to the film, while too low a temperature or too short a time may result in incomplete removal of moisture from the film, affecting the structural stability of the film. By properly selecting the drying temperature and time, the residual solvent in the coating process can be effectively removed to ensure the stability and uniformity of the film. At the same time, it can also avoid structural damage to the polyester film caused by too high a drying temperature or too long a drying time.

[0075] The temperature is between 40-60°C. A lower drying temperature helps control the structure of the film and avoids the negative impact of excessive temperature on the performance of the aerogel component or polyester film. Within this temperature range, the evaporation rate of the film's solvent is moderate, which can ensure the drying effect without causing excessive shrinkage or deformation of the film; the time is between 10-30 minutes. A shorter drying time may result in incomplete removal of the solvent in the film, affecting the stability and final quality of the film. A longer drying time can ensure that the film is completely dried, but it is also necessary to control the impact of too much time on the film.

[0076] S300, stretching and curing of the film: the film is stretched longitudinally and transversely, and heat-treated to completely cure the film, thereby obtaining a polyester film.

[0077] Preferably, longitudinal stretching is a key step in the film production process. The film is stretched to improve its mechanical properties and increase its strength and toughness. At this stage, the molecular chains of the film will be stretched in the longitudinal direction to increase the longitudinal strength and rigidity of the film. A lower stretching temperature can avoid thermal damage to the film, but it is still sufficient to make the molecular chains flow and rearrange, thereby enhancing the mechanical properties of the film. Within this temperature range, the film has sufficient ductility and will not deform excessively. A moderate stretching rate helps to form a uniform molecular orientation, avoiding film rupture due to excessive stretching or uneven stretching due to excessive stretching. This rate helps to maintain the quality of the film while ensuring production efficiency. By controlling the temperature and rate of longitudinal stretching, the longitudinal strength, toughness and durability of the film can be effectively improved, while avoiding deformation or performance degradation of the film due to excessive stretching.

[0078] Transverse stretching helps to improve the transverse strength and dimensional stability of the film. The film will be stretched in the transverse direction, so that the molecular chains are more orderly arranged in the transverse direction, thereby improving the strength and tear resistance of the film; higher stretching temperature can improve the flexibility of polyester film and reduce cracks and fractures during stretching. This temperature range helps to enhance the ductility of the film in the transverse direction, making the film less prone to brittle fracture during transverse stretching; moderate transverse stretching rate ensures that the film can be stretched evenly to avoid uneven stretching or internal stress. Too fast a stretching rate may cause uneven film stretching, while too slow a stretching rate will affect production efficiency; by optimizing the temperature and rate of transverse stretching, a more uniform transverse strength can be obtained, the tear resistance and durability of the film can be improved, and the stability and durability of the film in actual use can be ensured.

[0079] Heat treatment is a key step to ensure that the film is fully cured, remove residual stress and further improve the film performance. By heating at high temperature, the arrangement and crystallization of the polyester molecular chains will further enhance the mechanical properties and thermal stability of the film; the temperature at 120-160°C helps promote the crystallization process of the polyester film, improve its dimensional stability and heat resistance, and the appropriate heat treatment temperature can make the molecular structure of the polyester film more orderly, further improving its mechanical strength, thermal stability and aging resistance.

[0080] Furthermore, after step S300, it also includes: S400, surface treatment of the film: coating a polytetrafluoroethylene coating on the surface of the polyester film. By coating the polytetrafluoroethylene coating on the surface of the polyester film, not only can the chemical resistance, high temperature resistance, water resistance, anti-stickiness and wear resistance of the film be significantly enhanced, but also its sliding performance and appearance gloss can be improved. These improvements make the application field of the polyester film more extensive.

[0081] Example 1

[0082] This embodiment provides a polyester film and a preparation method thereof, and the specific operation steps are as follows:

[0083] S101, mixing terephthalic acid and tetrafluoroethylene in a mass ratio of 6:1 in a reactor, dissolving the mixture in xylene, adding titanium tetrachloride, heating the mixture at 200° C. to cause a polycondensation reaction, cooling the mixture, and filtering the mixture to obtain a polyester copolymer;

[0084] S111, adding tetraethoxysilane to a methanol solvent, and then adding water and hydrochloric acid to carry out a hydrolysis reaction and a polycondensation reaction, and forming a gel solution after standing for a certain period of time, wherein the ratio of the silicon source, the alcohol solvent and water is 1:5:3, the pH value of the hydrolysis reaction is 2, and the pH value of the polycondensation reaction is 6;

[0085] S112, soaking the gel solution in propanol, and after the propanol completely permeates the gel, drying it by supercritical drying to obtain an aerogel solution

[0086] S100, mixing reaction: mixing the aerogel solution and the polyester copolymer, and stirring to obtain a first mixture;

[0087] S200, film forming: coating the first mixture on a flat substrate through a tape casting machine, and drying it at a temperature of 50° C. for 20 minutes to form a film, wherein the coating thickness is 50 μm, and the coating speed of the tape casting machine is 15 m / min;

[0088] S300, stretching and curing the film: longitudinally stretching the film at a temperature of 85° C. and a rate of 700 mm / min and transversely stretching the film at a temperature of 110° C. and a rate of 800 mm / min, and heat-treating the film at a temperature of 140° C. to completely cure the film, thereby obtaining a polyester film;

[0089] S400, surface treatment of the membrane: coating the polyester film with a polytetrafluoroethylene coating to obtain the final product.

[0090] Example 2

[0091] This embodiment provides a polyester film and a preparation method thereof, and the specific operation steps are as follows:

[0092] S101, mixing ethylene glycol and acrylic acid in a mass ratio of 4:1 in a reaction kettle, dissolving the mixture in xylene, adding titanium tetrachloride, heating the mixture at 170° C. to cause a polycondensation reaction, cooling the mixture, filtering the mixture, and obtaining a polyester copolymer;

[0093] S111, adding tetraethyl orthosilicate to n-butanol solvent, and then adding water and ammonia water to carry out hydrolysis reaction and polycondensation reaction, and forming a gel solution after standing for a certain period of time, wherein the ratio of silicon source, alcohol solvent and water is 1:4:2, the pH value of hydrolysis reaction is 3, and the pH value of polycondensation reaction is 7;

[0094] S112, soaking the gel solution in ethanol, and after the ethanol completely permeates the gel, drying it by normal pressure drying method to obtain an aerogel solution

[0095] S100, mixing reaction: mixing the aerogel solution and the polyester copolymer, and stirring to obtain a first mixture;

[0096] S200, film forming: coating the first mixture on a flat substrate through a tape casting machine, and drying it at a temperature of 40° C. for 10 min to form a film, wherein the coating thickness is 10 μm, and the coating speed of the tape casting machine is 20 m / min;

[0097] S300, stretching and curing of the film: the film is longitudinally stretched at a temperature of 80°C and a rate of 600 mm / min and transversely stretched at a temperature of 90°C and a rate of 700 mm / min, and heat-treated at a temperature of 120°C to completely cure the film to obtain a polyester film.

[0098] Example 3

[0099] This embodiment provides a polyester film and a preparation method thereof, and the specific operation steps are as follows:

[0100] S101, mixing ethylene glycol and isocyanate in a mass ratio of 9:1 in a reaction kettle, dissolving them in xylene, adding titanium tetrachloride, heating them at a temperature of 230° C. to cause a polycondensation reaction, cooling them, filtering them, and obtaining a polyester copolymer;

[0101] S111, adding tetraethyl orthosilicate to n-butanol solvent, and then adding water and hydrochloric acid to carry out hydrolysis reaction and polycondensation reaction, and forming a gel solution after standing for a certain period of time, wherein the ratio of silicon source, alcohol solvent and water is 1:6:4, the pH value of hydrolysis reaction is 1, and the pH value of polycondensation reaction is 5;

[0102] S112, soaking the gel solution in ethanol, and after the ethanol completely permeates the gel, drying it by supercritical drying to obtain an aerogel solution

[0103] S100, mixing reaction: mixing the aerogel solution and the polyester copolymer, and stirring to obtain a first mixture;

[0104] S200, film forming: coating the first mixture on a flat substrate through a tape casting machine, and drying it at a temperature of 60° C. for 30 min to form a film, wherein the coating thickness is 100 μm, and the coating speed of the tape casting machine is 5 m / min;

[0105] S300, stretching and curing the film: longitudinally stretching the film at a temperature of 95°C and a rate of 800 mm / min and transversely stretching the film at a temperature of 120°C and a rate of 1000 mm / min, and heat-treating the film at a temperature of 160°C to completely cure the film to obtain a polyester film;

[0106] S400, surface treatment of the membrane: coating the polyester film with a polytetrafluoroethylene coating to obtain the final product.

[0107] Performance Testing

[0108] The comprehensive performance of the polyester films of Examples 1-3 was tested, and the specific test results are shown in Table 1;

[0109] The detection of each indicator in Table 1 is based on the following standards:

[0110] ①Tensile strength is measured with reference to GB / T1040.3-2006 "Determination of tensile properties of plastics Part 3: Test conditions for films and sheets";

[0111] ②The cutting area is 0.5m 2 , a polyester film with a thickness of 0.0001m is weighed;

[0112] ③The UV blocking rate is determined by referring to the UV transmittance in QC / T1170-2022 "Functional Films for Automotive Glass";

[0113] ④Vertical burning test of UL94VTM-0, VTM-1, VTM-2: Cut the polyester film into 200±5mm×50±1mm, make a mark along the length of 125mm, wrap it around a round rod with a diameter of 12.7mm, and glue the upper end with double-sided tape; Examples 1-3 each test 2 groups, each group of 10 samples, the first group is treated at (23±2)℃ and (50±5)%RH for 48 hours, and the second group is treated at (70±1)℃ for 168 hours. The final grade of the sample is based on the lowest grade of the two groups of samples;

[0114] Adjust the flame height to 20mm, apply the flame for 3s for the first time, anneal and record the flaming burning time t1, apply the flame for the second time for 3s, anneal and record the flaming burning time t2 and the flameless burning time t3, and record whether the burning exceeds the 125mm mark and whether there is any dripping that ignites the absorbent cotton below.

[0115] ⑤ Place microphones, receivers and test materials on both sides of the polyester film to ensure that the film material is sealed and fixed, measure the intensity of the sound on the sound source side and the receiving side respectively, and record the transmission loss in different frequency bands; calculate the Rw value: according to the ISO717-1 standard, combine the data of different frequency bands (, and calculate the sound insulation index of the polyester film;

[0116] Tensile strength / MPa Weight / g Flame retardant grade Sound insulation index / dB Example 1 7.5 58 VTM-0 54 Example 2 6.9 48 VTM-0 45 Example 3 7.4 60 VTM-0 52

[0117] It can be seen from the test results in Table 1 that the polyester film prepared by the present invention has excellent tensile strength, heat insulation, sound insulation, and is light in weight.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a polyester film, characterized in that: The preparation method of the polyester film comprises the following steps: S100, mixing reaction: mixing the aerogel solution and the polyester copolymer, and stirring to obtain a first mixture; S200, film forming: coating the first mixture on a flat substrate through a casting machine, and forming a film after drying; S300, stretching and curing the film: the film is stretched longitudinally and transversely, and heat-treated to completely cure the film, thereby obtaining the polyester film.

2. The preparation method according to claim 1, characterized in that: In the step S100, the method for preparing the polyester copolymer adopts the following steps: S101, mixing the polyester monomer and the comonomer, dissolving them in a first solvent, adding a catalyst, heating the polyester monomer to cause a polycondensation reaction, cooling and filtering the mixture, to obtain the polyester copolymer.

3. The preparation method according to claim 2, characterized in that: In step S101, The comonomer comprises at least one of a fluorine-containing monomer, an acrylic monomer, and an amino acid monomer; and / or The polyester monomer includes at least one of terephthalic acid and ethylene glycol; and / or The first solvent comprises xylene; and / or The catalyst includes, for example, titanium tetrachloride; and / or The mass ratio of the polyester monomer to the comonomer is about (4-9):1; and / or The temperature of the heating treatment is 170-230°C.

4. The preparation method according to claim 1, characterized in that: In step S100, the method for preparing the aerogel solution adopts the following steps: S111, adding a silicon source to an alcohol solvent, and then adding water and a catalyst to carry out a hydrolysis reaction and a polycondensation reaction, and forming a gel solution after standing for a certain period of time; S112, soaking the gel solution in a displacement solvent, and drying the gel after the displacement solvent completely permeates the gel to obtain the aerogel solution.

5. The preparation method according to claim 4, characterized in that: In step S111, The catalyst comprises at least one of hydrochloric acid and ammonia water; and / or The alcohol solvent includes at least one of methanol and n-butanol; and / or The silicon source comprises at least one of tetraethoxysilane and ethyl orthosilicate; and / or The ratio of the silicon source, the alcohol solvent and the water is 1:(4-6):(2-4); and / or The pH value of the hydrolysis reaction is in the range of 1-3; and / or The pH value of the polycondensation reaction is in the range of 5-7.

6. The preparation method according to claim 4, characterized in that: In step S112, The displacement solvent comprises at least one of ethanol and propanol; and / or The drying process includes supercritical drying or normal pressure drying.

7. The preparation method according to claim 1, characterized in that: In the step S200, The coating thickness is between 10-100 μm; and / or The coating speed of the casting machine is between 5-20 m / min; and / or The temperature of the drying process is between 40-60° C. and the time is between 10-30 minutes.

8. The preparation method according to claim 1, characterized in that: In step S300, The longitudinal stretching temperature is between 80-95°C and the stretching rate is between 600-800 mm / min; and / or The transverse stretching temperature is between 90-120°C and the stretching rate is 700-1000 mm / min; and / or The temperature of the heat treatment is 120-160°C.

9. The preparation method according to claim 1, characterized in that: After step S300, the method further includes: S400, surface treatment of the film: applying a polytetrafluoroethylene coating on the surface of the polyester film.

10. A polyester film, characterized in that: The polyester film is prepared by the preparation method according to any one of claims 1 to 9.