Tear-resistant and temperature-resistant composite film sealing material based on high-performance copolyester

Abstract

The invention discloses preparation and application of a high-performance copolyester tear-resistant and temperature-resistant composite film sealing material taking methyl m-hydroxybenzoate as a starting material, and belongs to the field of polymer synthesis and composite film materials. High-performance copolyester is obtained through transesterification and catalytic polycondensation reaction, then the high-performance copolyester, a tear-resistant modifier, an antioxidant and the like are subjected to composite processing to obtain the tear-resistant and temperature-resistant composite film sealing material, and the tear-resistant and temperature-resistant composite film sealing material is applied to temperature-resistant and tear-resistant sealing of electrical, mechanical, chemical and other equipment instruments and parts thereof.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of preparation and application of tear-resistant temperature-resistant copolyester composite film sealing material, belong to polymer synthesis and composite film material field, the composite film sealing material is applied to the sealing of electrical, machinery, chemical equipment and its parts, ensure that the good sealing of composite film material to equipment or the contact surface of parts under high temperature or severe cold environment. BACKGROUND

[0002] Polyester film has good thermodynamic performance, and shows considerable application prospect in the fields of chemical industry, machinery, communication, electrical equipment and hydraulic equipment and its parts. China, as a populous country, has huge power system and numerous chemical equipment and instruments, and the number of cable electrical equipment is large. Various factors such as gas, moisture in natural environment and working environment of equipment operation have high requirements for film sealing materials used in these fields. The use of film sealing material can effectively block the penetration of gas, liquid and solid particles, ensure the airtightness and safety of the system, especially the film sealing material used for related equipment and parts in high temperature and severe cold environment. High-performance film material with good sealing property can prevent the influence of harsh medium environment and ensure the safe use of equipment and parts.

[0003] High sealing film such as polyolefin, polyvinyl chloride, oxide film, multilayer co-extrusion film and other technologies have been developed and applied in all directions. Polyvinyl chloride is not resistant to high temperature, and has gradually withdrawn from the market due to safety and environmental factors. Polyolefin has good chemical stability, and has good safety and environmental friendly characteristics, and is suitable for some medical related material packaging, but its sealing performance and water vapor barrier performance are not enough to meet the sealing requirements of electrical equipment and medical instruments. With the continuous development of technology, high sealing polyester film is more and more widely used, and it is of great significance to develop high-performance polyester film sealing material.

[0004] In addition to the need to consider high temperature or cold medium temperature use environment, the tear resistance of the film sealing material is also very important for the use of chemical, electrical equipment and parts in some scenarios. Improving the tear resistance of polyester film material can be achieved by chemical copolymerization and physical blending methods. Most physical blending is to add elastomers to achieve the effect of tear resistance and toughness. Hyeri Kim reported a kind of polyester composite material, by adding a small amount of cellulose nanocrystals, the tensile strength and toughness of the composite material were improved, and a kind of polyester film with excellent tear resistance was prepared, the ultimate tensile strength was 64 MPa, the elongation at break was 690%, the ultimate tear strength was 1.4 KN / cm, and the tear toughness was 32 J / cm([1] Hyeri Kim, Hyeonyeol Jeon. Biodegradable nanocomposite of poly(ester-co-carbonate) and cellulose nanocrystals for tough tear-resistant disposable bags[J]. Green Chem. 2021, 23, 2293-2298.). Material blending to form composite material plays an important role in improving the comprehensive performance of the material.

[0005] In recent years, the development and application of organic sealing materials in the market are more and more widely, and polyvinyl chloride and polyurethane are more used, but they have defects such as poor high temperature resistance and weak ultraviolet resistance, and they are easy to release harmful gas when meeting high temperature, so the performance and environmental properties need to be improved. Graphite, ceramic and alloy, especially graphite, have excellent corrosion resistance and chemical stability, but their tensile strength is low and their tear resistance is weak, so the application scene of the material is limited, the alloy material has extremely high hardness and excellent wear resistance, but its impact toughness is low and its brittleness is high, and it is difficult to process, and alloy film sealing material has not been applied in the field of electrification and chemical equipment; polyester material is simple to synthesize and has good safety and environmental protection, and is a kind of material with excellent corrosion resistance and aging resistance, and has high tensile strength and ductility, and the polyester film sealing material is used in electrical, chemical machinery and equipment and various parts, and can maintain good sealing performance in the environment with sharp temperature change. The application discloses preparation and application of high-performance copolyester tear-resistant temperature-resistant composite film sealing material taking methyl m-hydroxybenzoate as a starting raw material. High-performance copolyester is obtained through ester exchange reaction and catalytic polycondensation reaction, and then the high-performance copolyester is compounded and processed with tear-resistant additives, antioxidants and the like to obtain tear-resistant temperature-resistant composite film sealing material, which is applied to temperature-resistant tear-resistant sealing of electrical, mechanical, chemical and the like equipment and parts thereof, such as sealing between pump equipment and parts such as chemical pumps, sealing of automobile engine gearbox parts, and the like, to ensure stable equipment performance and prolong equipment service life. The application is applied to end cover sealing of tower and tank and the like storage and transportation containers, sealing of natural gas pipeline interfaces, sealing of industrial liquid nitrogen equipment pipelines and parts, to ensure safe and effective transportation. In summary, the 5-300 mu m composite film sealing material of the patent application is applied to sealing of electrical, mechanical, chemical and the like equipment and parts thereof, and the tear-resistant temperature-resistant composite film sealing material of the application has a temperature resistance range of-210 DEG C to 400 DEG C, and can ensure good sealing of the composite film material on the contact surface of the equipment or parts in high temperature or severe cold environment. SUMMARY

[0006] In view of the above-mentioned status and problems, the present application aims to provide a preparation and application of a high-performance copolyester based on methyl-m-hydroxybenzoate and a tear-resistant and temperature-resistant copolyester composite film sealing material. The composite material has excellent strength and sealing performance, can be used for sealing of automobile engine gearbox components, protects internal components from damage, prevents water vapor from entering, and prolongs the service life of the product. It can also be used for sealing of end covers of tower and tank type storage and transportation containers, and sealing of natural gas pipeline interfaces to ensure safety and effectiveness during use. Specifically, a diester monomer M1 is obtained by coupling of methyl-m-hydroxybenzoate and 4,4-dichloro diphenyl ether, and a diol monomer M2 is obtained by coupling of 3-hydroxy-4-methoxybenzyl alcohol and dibromoethane. The diester monomer M1, the diol monomer M2, and dimethyl biphenyl-4,4-dicarboxylate are subjected to ester exchange reaction and catalytic polycondensation reaction to obtain a copolyester, which is further processed to prepare a tear-resistant and temperature-resistant composite film sealing material. The material can provide reliable sealing protection in various complex and harsh environments, and ensure the performance and service life of equipment and components.

[0007] In order to achieve the purpose of the present application, the technical solution adopted by the present application is as follows:

[0008] In order to achieve the technical solution of the present application, the present application discloses a preparation method and application of a tear-resistant and temperature-resistant composite film sealing material copolyester based on methyl-m-hydroxybenzoate. The application and the preparation method are described as follows:

[0009] 1. A preparation and application of a tear-resistant and temperature-resistant composite film sealing material based on high-performance copolyester, characterized in that the preparation adopts the following process method: 90 parts by mass of a high-performance copolyester P based on methyl-m-hydroxybenzoate, 5 parts of a tear-resistant modifier EN-01, and 5 parts of an antioxidant THP-24 are mixed uniformly by internal mixing, then extruded and pelletized by a double-screw extruder to obtain a tear-resistant and temperature-resistant composite material based on high-performance copolyester, and finally a film with a thickness of 5-300 μm is prepared by melt flow slushing and quenching process; the application of a tear-resistant and temperature-resistant composite film sealing material based on high-performance copolyester is characterized in that the composite film sealing material is applied to sealing surfaces of electrical, mechanical, chemical, and other equipment and components to ensure good sealing of the composite film sealing material to the contact surface of the equipment or components at a temperature not higher than 400℃ and not lower than -210℃.

[0010] The structure of the high-performance copolyester P based on methyl-m-hydroxybenzoate is shown in formula I:

[0011] In formula I, m is 55-65, and n is 65-80.

[0012] 2. Preparation and use of a high-performance copolyester-based tear-resistant temperature-resistant composite film sealing material, characterized in that the preparation of the high-performance copolyester P based on methyl meta-hydroxybenzoate comprises the following steps:

[0013] (1) Synthesis of diester monomer M1: methyl meta-hydroxybenzoate is added to a reactor, and tetrahydrofuran is added for stirring to dissolve it. The reactor is placed in an ice water bath, and triethylamine is added dropwise under stirring. 4,4-dichlorodiphenyl ether with CAS number 7158-32-9 is dissolved in tetrahydrofuran, and then added to the above reactor under stirring. The molar ratio of 4,4-dichlorodiphenyl ether, methyl meta-hydroxybenzoate, and triethylamine is 1:(2.0-2.2):1. It is placed in an ice water bath environment and continuously stirred for 2-3 hours. After being poured into ice water and standing for 1 hour, a solid is precipitated. The crude product of the reaction is washed three times with 5% sodium hydroxide aqueous solution. The filtered solid is washed with distilled water until it is neutral. It is dried in a 50°C oven for 1-2 hours to obtain diester monomer M1, which has the structure of Formula II:

[0014]

[0015] (2) Synthesis of diol monomer M2: dibromoethane and 3-hydroxy-4-methoxybenzyl alcohol with CAS number 124-05-0 are added to a reactor according to a substance amount ratio of 1:(2.0-2.2). N,N-dimethylformamide is added for stirring to dissolve it. Then, 1-1.2 times the substance amount of potassium carbonate is added. The reaction mixture is then heated to 80°C, and continuously stirred for 2-3 hours. After being poured into ice water, a solid is precipitated. The solid is filtered, and washed with distilled water until it is neutral. The solid is recrystallized with chloroform, and then filtered again. The solid is dried in a 50°C oven for 1-2 hours to obtain diol monomer M2, which has the structure of Formula III:

[0016]

[0017] (3) Preparation of high-performance copolyester P based on methyl meta-hydroxybenzoate:

[0018] Synthesis of crude copolyester: diester monomer M1 with the structure of , diol monomer M2 with the structure of , and dimethyl biphenyl-4,4-dicarboxylate with CAS number 792-74-5 are added to a reactor according to a certain molar ratio. A certain amount of catalyst is added. The reaction is stirred at a temperature of 220°C and under N2 atmosphere for 2 hours. Then, the reaction system is controlled at a vacuum degree of 120-130 Pa and a temperature of 320°C for polycondensation reaction for 1-2 hours to obtain crude copolyester;

[0019] Purification of copolyester: the crude copolyester was dissolved in chloroform, and the insoluble matter was filtered out. A sufficient amount of methanol was added dropwise to the clear solution until the white precipitate no longer increased. The precipitate filtered out was washed with cooled methanol for 2-3 times, and then dried in a 50℃ oven for 1-2h to obtain the desired high-performance copolyester P based on methyl m-hydroxybenzoate.

[0020] 3. Preparation of high-performance copolyester P based on methyl m-hydroxybenzoate, characterized in that the catalyst used in the synthesis of the copolyester is one of titanium (III) chloride, bismuth (III) neodecanoate, and dibutyl tin (II) oxide, and the amount of the catalyst used is 2%-3% of the mass of the diester monomer M1.

[0021] 4. A method for preparing high-performance copolyester P based on methyl m-hydroxybenzoate, characterized in that the molar ratio of the diester monomer M1 to the dimethyl biphenyl-4,4-dicarboxylate to the diol monomer M2 is 1:(1.0-1.2):(2.0-2.2).

[0022] Advantages

[0023] 1. The synthesis method of the copolyester based on methyl m-hydroxybenzoate prepared by the present application adopts a melt polycondensation method, and has the advantages of simple preparation process, easy control of reaction conditions, simple synthesis process, and environmentally friendly raw materials.

[0024] 2. Hyeri Kim ([1] Hyeri Kim, Hyeonyeol Jeon, Giyoung Shin, et al. Biodegradable nanocomposite of poly(ester-co-carbonate) and cellulose nanocrystals for tough tear-resistant disposable bags [J]. Green Chem. 2021, 23: 2293-2298.) reported a tear-resistant composite material with an ultimate tensile strength of 64 MPa, an elongation at break of 690%, an ultimate tear strength of 1.4 KN / cm, and a tear toughness of 32 J / cm. The copolyester composite material based on methyl m-hydroxybenzoate prepared by the present application has an ultimate tensile strength of 92-102 MPa, an elongation at break of 1070%-1210%, an ultimate tear strength of 2.1-2.3 KN / cm, and a tear toughness of 56-59 J / cm. In comparison, the mechanical properties of the copolyester composite material based on methyl m-hydroxybenzoate prepared by the present application are significantly enhanced and exhibit excellent tear resistance.

[0025] 3、Polytetrafluoroethylene film temperature resistance is -190℃~370℃, its tensile strength is about 8MPa, the copolyester composite film material based on m-hydroxybenzoic acid methyl ester prepared by the application has temperature resistance of -210℃~400℃, the temperature resistance range is wider, the tensile strength after 400℃ high temperature nitrogen and ultra-low temperature liquid nitrogen circulation treatment is 68~73MPa, and good mechanical properties are still maintained, which is superior to polytetrafluoroethylene and Hyeri Kim [1] The tensile strength of the reported composite material is excellent in temperature resistance and mechanical properties.

[0026] 4、Yang Yu([2]Yu Yang, Liu Sixiao, Liu Huan, et al. A renewable tricyclic building block towards synthesis of biobased polyesters with high-performance and hydrolyzability[J]. Polymer Degradation and Stability. 2023, 217: 110514-110524.) reported a new type of polyester CBPC material, the number average molecular weight M n n of which is 3.2×10 4 g / mol, the molecular weight distribution coefficient PDI is 2.38, the glass transition temperature T g is 100.8℃, the melting point T m is 248.6℃, and the thermal decomposition temperature T d(5％) is 372℃. The number average molecular weight M n of the high-performance copolyester P based on m-hydroxybenzoic acid methyl ester prepared by the application is 5.9×10 4 ~6.3×10 4 g / mol, the molecular weight distribution coefficient PDI is 2.61~2.73, the glass transition temperature T g is 128.4~136.2℃, the melting point T m is 446.8~453.2℃, and the thermal decomposition temperature T d(5％) is 517.3~525.9℃. Compared with the above, the molecular weight and thermal stability of the copolyester P based on m-hydroxybenzoic acid methyl ester prepared by the application are significantly improved.

[0027] 5、Manyuan Yin([3]Manyuan Yin,Xiaoqin Zhang,Hao Wang,et al.High-Barrier-Property Copolyesters Based on Spiroglycol with Controlled Degradation[J].ACS Sustainable Chem.Eng.2024,12:6343-6354.) reported a kind of polyester material PBAT, its CO2 permeability coefficient is 5.9 x 10 -10 cm 3 ·cm / cm 2· s·cm, O2 permeability coefficient is 7.6 x 10 -11 cm 3 ·cm / cm 2 ·s·cm, water vapor transmission rate is 3.52 x 10 -13 g·cm / cm 2 ·s·Pa;The CO2 permeability coefficient of the copolyester composite material based on m-hydroxybenzoic acid methyl ester prepared by the application is 2.1 x 10 -12 ~ 2.7 x 10 -12 cm 3 ·cm / cm 2 ·s·cm, O2 permeability coefficient is 8.1 x 10 -13 ~ 8.9 x 10 -13 cm 3 ·cm / cm 2 ·s·cm, water vapor transmission rate is 1.37 x 10 -15 ~ 1.47 x 10 -15 g·cm / cm 2 ·s·Pa, the CO2 permeability coefficient and O2 permeability coefficient of the copolyester composite material prepared by the application are determined at different temperatures (-20℃, 25℃, 200℃), the CO2 permeability coefficient of the copolyester composite material is between 2.1 x 10 -12 ~ 4.8 x 10 -12 cm 3 ·cm / cm 2 ·s·cm, O2 permeability coefficient is between 8.1 x 10 -13 ~ 1.9 x 10 -12 cm 3 ·cm / cm 2 ·s·cm, it can be seen that the sealing performance of the copolyester composite film material at different temperatures is very stable. In contrast, the copolyester composite material based on m-hydroxybenzoic acid methyl ester prepared by the application shows excellent sealing performance.

[0028] Specific implementation cases

[0029] To further illustrate the specific circumstances of the present application, the following further illustrates the present application in conjunction with specific examples, but the present application is not limited by the examples, and the required raw materials are all commonly sold drugs on the market.

[0030] Molecular weight test in the examples: gel permeation chromatography test was tested by Waters GPC instrument (Waters 410), eluent was chromatographic grade chloroform, and standard solution was polystyrene solution.

[0031] Thermal stability test in the examples: DSC test was tested by TAQ2000 instrument, and the test method was: under nitrogen atmosphere, 10℃ / min, from 30℃ to 500℃, 10min at 500℃, 10℃ / min, from 30℃ to 500℃, and the same rate was increased to 500℃. Thermal gravimetric analysis (TGA) test was carried out by Perkin-Elmer (Pyris 1TGA) instrument, sample type was polyester powder, and test method was: under nitrogen atmosphere, 10min at 100℃, 10℃ / min from 100℃ to 800℃.

[0032] Mechanical property test in the examples: sample test bar tensile test was carried out according to the standard requirements of GB / T1040.2-2006, and the tensile rate was 20mm / min. Elongation at break test was carried out according to the standard requirements of GB / T1040.3-2006.

[0033] Temperature resistance test in the examples: the sample was subjected to high and low temperature cycle treatment, i.e. high and low temperature cycle treatment after high temperature nitrogen treatment at 400℃ and low temperature liquid nitrogen cooling at-210℃, and the sample was subjected to tensile test according to the standard requirements of GB / T1040.2-2006.

[0034] Sealing performance test in the examples: GPT-201H differential pressure gas permeation instrument was used to detect the gas permeability of the sample under different temperatures at 50% relative humidity. The sample was made into a circular film with a diameter of 95mm and a surface area of 33.18cm 2 . After the sample was melted at normal pressure, the permeability coefficient of the film sample to two kinds of gas at different temperatures was determined under the conditions of high purity oxygen and high purity carbon dioxide respectively; LabtrinkW3-060 water vapor transmission rate tester was used to make the sample into a circular film with a diameter of 74mm and a surface area of 33cm 2 . The water vapor transmission rate of the sample film was measured under 90% relative humidity.

[0035] Example 1

[0036] Synthesis of diester monomer M1 : 6.6468 g (0.04 mol) of methyl m-hydroxybenzoate was added into a 100 mL round-bottom flask, 20 mL of tetrahydrofuran was added to stir to dissolve, the round-bottom flask was placed in an ice-water bath, 2.0238 g (0.02 mol) of triethylamine was added dropwise under stirring, then 5.9024 g (0.02 mol) of 4,4-dichloro-diphenyl ether was dissolved in 20 mL of tetrahydrofuran, which was then added to the above-mentioned round-bottom flask under stirring, the reaction was continuously stirred in an ice-water bath environment for 2 hours, the solid was precipitated after being poured into ice water and standing for 1 hour, the crude product of the reaction was washed three times with 5% sodium hydroxide aqueous solution, the filtered solid was washed with distilled water until neutral, and was dried in a 50°C oven for 2 h to obtain diester monomer M1 : 9.4272 g, yield: 84.94%. Synthesis of diol monomer M2: 3.7572 g (0.02 mol) of dibromoethane and 6.1665 g (0.040 mol) of 3-hydroxy-4-methoxybenzyl alcohol were added into a 100 mL round-bottom flask, 30 mL of N,N-dimethylformamide was added as a reaction solvent, a magnetic stirrer was added to stir to dissolve, then 2.7641 g of potassium carbonate was added, and then the reaction mixture was heated to 80°C, continuously stirred for 2 hours, then poured into ice water to precipitate a solid, the solid was filtered, washed with distilled water until neutral, and then recrystallized with chloroform, the filtered solid was dried in a 50°C oven for 2 h to obtain diol monomer M2: 5.8172 g, yield: 86.99%.

[0037] Preparation of high-performance copolyester P1 based on methyl m-hydroxybenzoate: 1.1089 g (2 mmol) of diester monomer M1, 1.3375 g (4 mmol) of diol monomer M2, and 0.5406 g (2 mmol) of dimethyl biphenyl-4,4-dicarboxylate were added to a reaction vessel under nitrogen protection, 0.0268 g of titanium (III) chloride was added, and the reaction was stirred at a temperature of 220°C and under N2 atmosphere for 2 hours, then the vacuum degree of the reaction system was controlled at 120-130 Pa, and the polycondensation reaction was carried out at a temperature of 320°C for 1 hour to obtain a crude copolyester. The crude copolyester was dissolved with chloroform, the insoluble matter was filtered out, sufficient methanol was added dropwise to the clear solution until the white precipitate no longer increased, the filtered precipitate was washed with cooled methanol for 3 times, and then the obtained solid was dried in a 50°C oven for 1 h to obtain high-performance copolyester P1.

[0038] Further through composite processing, a high tear resistance and high sealing composite film material based on methyl m-hydroxybenzoate is prepared, which is applied to the sealing of liquid nitrogen equipment, pipelines and parts in industry, to ensure good sealing of the composite film material to the equipment in the ultra-low temperature working environment of-210℃, and to maintain normal operation. The composite film material is prepared by the following method: 90 parts by mass of high-performance copolyester P1, 5 parts of tear resistance modifier EN-01, and 5 parts of antioxidant THP-24 are mixed uniformly in a closed mixer, then extruded and pelletized by a twin-screw extruder, and finally prepared into a copolyester composite film with a thickness of 250 μm by a melt flow slaying and quenching process. The mechanical properties, thermal stability and sealing performance test results of the material are shown in Tables 1, 2, 3 and 4.

[0039] Example 2

[0040] Synthesis of diester monomer M1: 6.7797 g (0.0408 mol) of methyl m-hydroxybenzoate was added to a 100 mL round-bottom flask, 20 mL of tetrahydrofuran was added to stir to dissolve it, the round-bottom flask was placed in an ice water bath, 2.0238 g (0.02 mol) of triethylamine was added dropwise under stirring, then 5.9024 g (0.02 mol) of 4,4-dichloroformyl diphenyl ether was dissolved in 20 mL of tetrahydrofuran, then it was added to the above-mentioned round-bottom flask under stirring, the reaction was continuously stirred for 3 hours in an ice water bath environment, the solid was precipitated after being poured into ice water and standing for 1 hour, the crude product of the reaction was washed with 5% sodium hydroxide aqueous solution for three times, the filtered solid was washed with distilled water until it was neutral, and then it was dried in a 50℃ oven for 1 h to obtain diester monomer M1: 9.6312 g, yield: 86.78%.

[0041] Synthesis of diol monomer M2: 3.7572 g (0.02 mol) of dibromoethane and 6.5365 g (0.0424 mol) of 3-hydroxy-4-methoxybenzyl alcohol were added to a 100 mL round-bottom flask, 30 mL of N,N-dimethylformamide was added as a reaction solvent, a magnetic stirrer was added to stir to dissolve it, then 2.7641 g of potassium carbonate was added, and then the reaction mixture was heated to 80℃, continuously stirred for 2 hours, then poured into ice water to precipitate a solid, the solid was filtered, washed with distilled water until it was neutral, recrystallized with chloroform, and then the filtered solid was dried in a 50℃ oven for 2 h to obtain diol monomer M2: 5.8341 g, yield: 87.24%.

[0042] Preparation of high-performance copolyester P2 based on methyl-m-hydroxybenzoate: 1.1089 g (2 mmol) of diester monomer M1, 1.3375 g (4 mmol) of diol monomer M2 and 0.5946 g (2.2 mmol) of dimethyl biphenyl-4,4-dicarboxylate were added to a reaction vessel under nitrogen protection, 0.0401 g of titanium (III) chloride was added, and the reaction was stirred at a temperature of 220°C and under N2 atmosphere for 2 hours, after which the reaction system was controlled at a vacuum degree of 120-130 Pa and a temperature of 320°C for polycondensation for 1 hour to obtain a crude copolyester. The crude copolyester was dissolved with chloroform, and the insoluble matter was filtered out. Sufficient methanol was added dropwise to the clear solution until the white precipitate no longer increased. The precipitate filtered out was washed with cooled methanol for 3 times, and after being filtered again, the obtained solid was placed in a 50°C oven for drying for 1 h to obtain high-performance copolyester P2.

[0043] Further, a high-sealing composite film material based on methyl-m-hydroxybenzoate with high tear resistance was prepared through composite processing, which was applied to the sealing connection of automobile engine gearbox systems and components to ensure that the equipment maintains excellent sealing performance at high temperatures. The method for processing and preparing the composite film material is as follows: 90 parts by mass of high-performance copolyester P2, 5 parts of tear-resistant modifier EN-01 and 5 parts of antioxidant THP-24 were mixed uniformly by internal mixing, then extruded and granulated by a twin-screw extruder, and finally prepared into a copolyester composite film with a film thickness of 150 μm by melt flow slushing and quenching process. The test results of the mechanical properties, thermal stability and sealing performance of the material are shown in Tables 1, 2, 3 and 4.

[0044] Example 3

[0045] Synthesis of diester monomer Ml: 6.9127 g (0.0416 mol) of methyl m-hydroxybenzoate was added into a 100 mL round-bottom flask, 20 mL of tetrahydrofuran was added to stir to dissolve, the round-bottom flask was placed in an ice-water bath, 2.0238 g (0.02 mol) of triethylamine was added dropwise under stirring, then 5.9024 g (0.02 mol) of 4, 4-dicarbonyl dichloride diphenyl ether was dissolved in 20 mL of tetrahydrofuran, which was then added to the above-mentioned round-bottom flask under stirring, the reaction was continuously stirred in an ice-water bath environment for 2 hours, the solid was precipitated after being poured into ice water and standing for 1 hour, the crude product of the reaction was washed with 5% sodium hydroxide aqueous solution for three times, the filtered solid was washed with distilled water until neutral, and was dried in a 50°C oven for 2 h to obtain diester monomer Ml: 9.7265 g, yield: 87.72%. Synthesis of diol monomer M2: 3.7572 g (0.02 mol) of dibromoethane and 6.5982 g (0.0428 mol) of 3-hydroxy-4-methoxybenzyl alcohol were added into a 100 mL round-bottom flask, 30 mL of N, N-dimethylformamide was added as a reaction solvent, a magnetic stirrer was added to stir to dissolve, then 3.0405 g of potassium carbonate was added, and then the reaction mixture was heated to 80°C, continuously stirred for 2 hours, then poured into ice water to precipitate a solid, the solid was filtered, washed with distilled water until neutral, and the solid was recrystallized with chloroform, then filtered again, and the obtained solid was dried in a 50°C oven for 1 h to obtain diol monomer M2: 6.0537 g, yield: 90.58%.

[0046] Preparation of high-performance copolyester P3 based on methyl m-hydroxybenzoate: 1.1089 g (2 mmol) of diester monomer Ml, 1.4043 g (4.2 mmol) of diol monomer M2, and 0.6487 g (2.4 mmol) of dimethyl biphenyl-4, 4-dicarboxylate were added to a reaction vessel under nitrogen protection, 0.0268 g of bismuth (III) neodecanoate was added, and the reaction was stirred at a temperature of 220°C and under N2 atmosphere for 2 hours, then the vacuum degree of the reaction system was controlled at 120-130 Pa, and the polycondensation reaction was carried out at a temperature of 320°C for 2 hours to obtain a crude copolyester. The crude copolyester was dissolved with chloroform, the insoluble matter was filtered out, sufficient methanol was added dropwise to the clear solution until the white precipitate no longer increased, the filtered precipitate was washed with cooled methanol for 3 times, and then filtered again, and the obtained solid was dried in a 50°C oven for 1 h to obtain high-performance copolyester P3.

[0047] Further through the composite processing preparation of a kind of based on methyl m-hydroxybenzoate tear resistance high sealing composite film material, applied to natural gas transportation field, the equipment, instrument and pipeline and its spare parts using the composite film material sealing connection, ensure the safe and effective transportation of gas, especially in extremely cold environment using the composite film sealing material, because its temperature resistance and tear resistance performance is good, its safety and service life are guaranteed. The method for preparing the composite film material is as follows: 90 parts of high-performance copolyester P3, 5 parts of tear resistance modifier EN-01 and 5 parts of antioxidant THP-24 are mixed uniformly in a closed mixer, then extruded and pelletized by a twin-screw extruder, and finally prepared into a copolyester composite film with a film thickness of 200 μm by a melt flow slushing and quenching process. The test results of the mechanical properties, thermal stability and sealing performance of the material are shown in Tables 1, 2, 3 and 4.

[0048] Example 4

[0049] Synthesis of diester monomer M1: 7.0456 g (0.0424 mol) of methyl m-hydroxybenzoate was added to a 100 mL round-bottom flask, 20 mL of tetrahydrofuran was added and stirred to dissolve it, the round-bottom flask was placed in an ice water bath, 2.0238 g (0.02 mol) of triethylamine was added dropwise under stirring, then 5.9024 g (0.02 mol) of 4,4-dichloroformyl diphenyl ether was dissolved in 20 mL of tetrahydrofuran, then it was added to the above-mentioned round-bottom flask under stirring, the reaction was continuously stirred for 3 hours in an ice water bath environment, after being poured into ice water and standing for 1 hour, a solid was precipitated, the crude product of the reaction was washed with 5% sodium hydroxide aqueous solution for three times, the filtered solid was washed with distilled water until it was neutral, and then it was dried in a 50°C oven for 1 h, to obtain diester monomer M1: 9.9382 g, yield: 89.62%. Synthesis of diol monomer M2: 3.7572 g (0.02 mol) of dibromoethane and 6.6598 g (0.0432 mol) of 3-hydroxy-4-methoxybenzyl alcohol were added to a 100 mL round-bottom flask, 30 mL of N,N-dimethylformamide was added as a reaction solvent, a magnetic stirrer was added to stir to dissolve it, then 3.0405 g of potassium carbonate was added, and then the reaction mixture was heated to 80°C, continuously stirred for 2 hours, then poured into ice water to precipitate a solid, the solid was filtered, washed with distilled water until it was neutral, and then recrystallized from chloroform, the filtered solid was dried in a 50°C oven for 2 h, to obtain diol monomer M2: 5.9873 g, yield: 89.53%.

[0050] Preparation of high-performance copolyester P4 based on methyl-m-hydroxybenzoate: 1.1089 g (2 mmol) of diester monomer M1, 1.4043 g (4.2 mmol) of diol monomer M2 and 0.6487 g (2.4 mmol) of dimethyl biphenyl-4,4-dicarboxylate were added to a reaction vessel under nitrogen protection, 0.0401 g of bismuth (III) neodecanoate was added, and the reaction was stirred at a temperature of 220°C under N2 atmosphere for 2 hours, and then the reaction system was controlled at a vacuum degree of 120-130 Pa and a temperature of 320°C for 1 hour of polycondensation reaction to obtain a crude copolyester. The crude copolyester was dissolved with chloroform, and the insoluble matter was filtered out. Sufficient methanol was added dropwise to the clear solution until the white precipitate no longer increased. The precipitate filtered out was washed with cooled methanol for 3 times, and then filtered again. The obtained solid was placed in a 50°C oven for drying for 1 h to obtain high-performance copolyester P4.

[0051] Further, a high-sealing composite film material based on methyl-m-hydroxybenzoate with high tear resistance was prepared by composite processing, which was applied to the end cap sealing of storage and transportation containers such as towers and tanks to strengthen the sealing performance. The method for processing and preparing the composite film material is as follows: 90 parts by mass of high-performance copolyester P4, 5 parts of tear-resistant modifier EN-01 and 5 parts of antioxidant THP-24 were mixed uniformly by internal mixing, then extruded and granulated by a twin-screw extruder, and finally prepared into a copolyester composite film with a film thickness of 50 μm by melt flow slush quenching process. The test results of the mechanical properties, thermal stability and sealing performance of the material are shown in Tables 1, 2, 3 and 4.

[0052] Example 5

[0053] Synthesis of diester monomer Ml: 7.1785 g (0.0432 mol) of methyl m-hydroxybenzoate was added into a 100 mL round bottom flask, 20 mL of tetrahydrofuran was added to stir to dissolve, the round bottom flask was placed in an ice water bath, 2.0238 g (0.02 mol) of triethylamine was added dropwise under stirring, then 5.9024 g (0.02 mol) of 4, 4-dicarbonyl dichloride diphenyl ether was dissolved in 20 mL of tetrahydrofuran, then it was added into the above-mentioned round bottom flask under stirring, the reaction was continuously stirred in an ice water bath environment for 3 hours, after being poured into ice water and standing for 1 hour, a solid was precipitated, the crude product of the reaction was washed with 5% sodium hydroxide aqueous solution for three times, the filtered solid was washed with distilled water until neutral, and dried in a 50°C oven for 2 h to obtain diester monomer Ml: 9.8726 g, yield: 89.03%. Synthesis of diol monomer M2: 3.7572 g (0.02 mol) of dibromoethane and 6.7215 g (0.0436 mol) of 3-hydroxy-4-methoxybenzyl alcohol were added into a 100 mL round bottom flask, 30 mL of N, N-dimethylformamide was added as a reaction solvent, a magnetic stirrer was added to stir to dissolve, then 3.3169 g of potassium carbonate was added, then the reaction mixture was heated to 80°C, after continuously stirring for 2 hours, the solid was precipitated by pouring into ice water, the solid was filtered, the solid was washed with distilled water until neutral, the solid was recrystallized with chloroform and then filtered again, and the obtained solid was dried in a 50°C oven for 1 h to obtain diol monomer M2: 5.9382 g, yield: 88.79%.

[0054] Preparation of high-performance copolyester P5 based on methyl m-hydroxybenzoate: 1.1089 g (2 mmol) of diester monomer Ml, 1.4712 g (4.4 mmol) of diol monomer M2, and 0.5406 g (2 mmol) of dimethyl biphenyl-4, 4-dicarboxylate were added into a reaction vessel, 0.0268 g of dibutyltin oxide (II) was added, and the reaction was stirred at a temperature of 220°C under N2 atmosphere for 2 hours, then the vacuum degree of the reaction system was controlled at 120-130 Pa, and the polycondensation reaction was carried out at a temperature of 320°C for 1 hour to obtain a crude copolyester. The crude copolyester was dissolved in chloroform, the insoluble matter was filtered out, sufficient methanol was added dropwise into the clear solution until the white precipitate no longer increased, the filtered precipitate was washed with cooled methanol for 2 times, and then the obtained solid was dried in a 50°C oven for 1 h to obtain high-performance copolyester P5.

[0055] Further through composite processing, a high tear resistance and high sealing composite film material based on methyl m-hydroxybenzoate is prepared, which is applied to the sealing treatment of the thread connection of the joint surface in the elbow, spigot and cylinder of the pipeline in water conservancy projects, to ensure the good sealing of the composite material to the equipment. The method for preparing the composite film material is as follows: 90 parts by mass of high-performance copolyester P5, 5 parts of tear resistance modifier EN-01 and 5 parts of antioxidant THP-24 are mixed uniformly in a closed mixer, then extruded and pelletized by a twin-screw extruder, and finally prepared into a copolyester composite film with a film thickness of 5 μm by a melt flow slushing and quenching process. The test results of the mechanical properties, thermal stability and sealing performance of the material are shown in Tables 1, 2, 3 and 4.

[0056] Example 6

[0057] Synthesis of diester monomer M1: 7.3115 g (0.044 mol) of methyl m-hydroxybenzoate was added to a 100 mL round-bottom flask, 20 mL of tetrahydrofuran was added for stirring to dissolve it, the round-bottom flask was placed in an ice water bath, 2.0238 g (0.02 mol) of triethylamine was added dropwise under stirring, then 5.9024 g (0.02 mol) of 4,4-dichloroformyl diphenyl ether was dissolved in 20 mL of tetrahydrofuran, then it was added to the above-mentioned round-bottom flask under stirring, the reaction was continuously stirred in an ice water bath environment for 3 hours, after being poured into ice water and standing for 1 hour, a solid was precipitated, the crude product of the reaction was washed with 5% sodium hydroxide aqueous solution for three times, the filtered solid was washed with distilled water until it was neutral, and then it was dried in a 50°C oven for 2 h, to obtain diester monomer M1: 9.764 g, yield: 88.05%. Synthesis of diol monomer M2: 3.7572 g (0.02 mol) of dibromoethane and 6.7832 g (0.044 mol) of 3-hydroxy-4-methoxybenzyl alcohol were added to a 100 mL round-bottom flask, 30 mL of N,N-dimethylformamide was added as a reaction solvent, a magnetic stirrer was added for stirring to dissolve it, then 3.3169 g of potassium carbonate was added, then the reaction mixture was heated to 80°C, and after continuously stirring for 2 hours, the solid was precipitated by pouring into ice water, the solid was filtered, washed with distilled water until it was neutral, and then recrystallized from chloroform, the filtered solid was dried in a 50°C oven for 2 h, to obtain diol monomer M2: 5.9175 g, yield: 88.49%.

[0058] Preparation of high-performance copolyester P6 based on methyl-m-hydroxybenzoate: 1.1089 g (2 mmol) of diester monomer M1, 1.4712 g (4.4 mmol) of diol monomer M2, and 0.5406 g (2 mmol) of dimethyl diphenyl-4,4-dicarboxylate were added to a reaction vessel under nitrogen protection, 0.0401 g of dibutyltin oxide (II) was added, and the reaction was stirred at a temperature of 220 ℃ and under N2 atmosphere for 2 hours, and then the vacuum degree of the reaction system was controlled at 120-130 Pa, and the temperature was controlled at 320 ℃ for 2 hours of polycondensation reaction to obtain a crude copolyester. The crude copolyester was dissolved in chloroform, and the insoluble matter was filtered out. Sufficient methanol was added dropwise to the clear liquid until the white precipitate no longer increased. The precipitate filtered out was washed with cooled methanol for 3 times, and then filtered again. The obtained solid was placed in a 50 ℃ oven for drying for 1 h to obtain a high-performance copolyester P6.

[0059] Further, a high-sealing composite film material based on methyl-m-hydroxybenzoate is prepared by composite processing, which is applied to the sealing of 250-400 ℃, 3.0-5.0 MP high-pressure high-temperature pipeline valves and joints to prevent the leakage of internal high-pressure high-temperature medium and ensure the good sealing connection of the composite film material to the pipeline and parts. The method for processing and preparing the composite film material is as follows: 90 parts by mass of high-performance copolyester P6, 5 parts of tear-resistant modifier EN-01, and 5 parts of antioxidant THP-24 are mixed uniformly by internal mixing, then extruded and granulated by a twin-screw extruder, and finally prepared into a copolyester composite film with a film thickness of 300 μm by a melt flow slush quenching process. The test results of the mechanical properties, thermal stability, and sealing performance of the material are shown in Tables 1, 2, 3, and 4.

[0060] Table 1 Comparison of mechanical property data of composite copolyester materials of Examples 1-6 and comparative samples

[0061]

[0062] [1] Hyeri Kim, Hyeonyeol Jeon, Giyoung Shin, et al. Biodegradable nanocomposite of poly(ester-co-carbonate) and cellulose nanocrystals for tough tear-resistant disposable bags [J]. Green Chem. 2021, 23: 2293-2298.

[0063] Table 2 Comparison of performance data of copolyesters in Examples 1-6 and comparative samples CBPC

[0064] Example samples M n (g / mol) PID T g / ℃]] T m / ℃]] T d(5％) / ℃]] 1 5.9 x 10 4 ]]> 2.61 128.4 446.8 517.3 2 6.2 x 10 4 ]]> 2.65 130.6 448.7 520.8 3 6.0 x 10 4 ]]> 2.68 132.5 450.4 523.2 4 5.9 x 10 4 ]]> 2.71 133.9 449.4 522.9 5 6.1 x 10 4 ]]> 2.69 135.1 452.7 524.6 6 6.3 x 10 4 ]] 2.73 136.2 453.2 525.9 Control [2] ]] 3.2 x 10 4 ]]> 2.38 100.8 248.6 372

[0065] [2] Yu Yang, Liu Sixiao, Liu Huan, et al. A renewable tricyclic building block towards synthesis of biobased polyesters with high-performance and hydrolyzability [J]. Polymer Degradation and Stability. 2023, 217: 110514-110524.

[0066] Table 3 Sealing performance comparison of composite copolyester materials of examples 1-6 and comparative sample PBAT

[0067]

[0068] [3] Manyuan Yin, Xiaoqin Zhang, Hao Wang, et al. High-Barrier-Property Copolyesters Based on Spiroglycol with Controlled Degradation [J]. ACS Sustainable Chem. Eng. 2024, 12: 6343-6354.

[0069] Table 4 Sealing performance of composite copolyester materials of examples 1-6 at different temperatures

[0070]

[0071] From the data comparison in Table 1, the ultimate tensile strength of the high-performance copolyesters P1-P6 based on methyl m-hydroxybenzoate prepared by the present application is 92-102 MPa, the elongation at break is 1070%-1210%, the ultimate tear strength is 2.1-2.3 KN / cm, and the tear toughness is 56-59 J / cm. Compared with the polyester composite material reported by Hyeri Kim, the mechanical properties of the high-performance copolyesters P1-P6 prepared by the present application are significantly enhanced, the ultimate tensile strength is increased by 28-38 MPa compared with the polyester material reported by Hyeri Kim, the elongation at break is increased by 380%-520% compared with the polyester material reported by Hyeri Kim, the ultimate tear strength is increased by 0.7-0.9 KN / cm compared with the polyester material reported by Hyeri Kim, and the tear toughness is increased by 24-27 J / cm compared with the polyester material reported by Hyeri Kim. In comparison, the mechanical properties of the copolyester composite material based on methyl m-hydroxybenzoate prepared by the present application are significantly enhanced, and excellent tear resistance is exhibited. The tensile strength of the copolyester composite film material based on methyl m-hydroxybenzoate prepared by the present application after high-low temperature cycle treatment at 400℃ high temperature and liquid nitrogen cooling is 68-73 MPa, the temperature resistance of polytetrafluoroethylene is -190℃-370℃, and the tensile strength is about 8 MPa. It can be seen that the composite film material prepared by the present application is superior to the composite material reported by Hyeri Kim [1] and polytetrafluoroethylene. In comparison, the temperature resistance range of the copolyester composite material based on methyl m-hydroxybenzoate prepared by the present application is -210℃-400℃, and excellent temperature resistance is exhibited.

[0072] From the data comparison in Table 2, the copolyesters P1-P6 are synthesized by using diester monomer M1, diol monomer M2 and diphenyl-4,4-dicarboxylic acid dimethyl ester as raw materials. The number average molecular weight of the copolyesters P1-P6 based on methyl m-hydroxybenzoate prepared by the present application is 5.9x10 4 -6.3x10 4 g / mol, the molecular weight distribution coefficient PDI is 2.61-2.73, the glass transition temperature T g is 128.4-136.2℃, the melting point T m is 446.8-453.2℃, and the thermal decomposition temperature T d(5％) is 517.3-525.9℃. Compared with the polyester material CBPC reported by Yang Yu, the copolyesters P1-P6 prepared by the present application have improved molecular weight and thermal stability, the glass transition temperature T g is increased by 27.6-35.4℃ compared with the polyester material CBPC, the melting point T m is increased by 198-204.6℃ compared with the polyester material CBPC, and the thermal decomposition temperature T d(5％)Compared with the polyester material CBPC, the temperature is increased by 145.3-153.9 DEG C. In contrast, the molecular weight and thermal stability of the prepared copolyester P based on methyl m-hydroxybenzoate are significantly improved.

[0073] As can be seen from the data comparison in Table 3, the CO2permeability coefficient of the prepared high-performance copolyester P1-P6 based on methyl m-hydroxybenzoate is 2.1 x 10 -12 ~ 2.7 x 10 -12 cm 3 ·cm / cm 2 ·s·cm, the O2permeability coefficient is 8.1 x 10 -13 ~ 8.9 x 10 -13 cm 3 ·cm / cm 2 ·s·cm, and the water vapor transmission rate is 1.37 x 10 -15 ~ 1.47 x 10 -15 g·cm / cm 2 ·s·Pa. The sealing performance of the prepared copolyester P1-P6 is obviously enhanced compared with the polyester composite material PBAT reported by Manyuan Yin, the CO2permeability coefficient is reduced by about 280 times compared with the polyester material PBAT, the O2permeability coefficient is reduced by about 90 times compared with the polyester material PBAT, and the water vapor transmission rate is reduced by about 252 times compared with the polyester material PBAT. In contrast, the copolyester composite material based on methyl m-hydroxybenzoate prepared by the present application exhibits excellent sealing performance.

[0074] As can be seen from the data comparison in Table 4, the CO2permeability coefficient of the prepared copolyester composite film material P1-P6 based on methyl m-hydroxybenzoate is 2.1 x 10 -12 ~ 2.7 x 10 -12 cm 3 ·cm / cm 2 ·s·cm at 25 DEG C, the CO2permeability coefficient is 4.1 x 10 -12 ~ 4.8 x 10 -12 cm 3 ·cm / cm 2 ·s·cm at 200 DEG C, the CO2permeability coefficient of the material is 3.0 x 10 -12 ~ 3.9 x 10 -12 cm 3 ·cm / cm 2 ·s·cm at -20 DEG C; the O2permeability coefficient of the material is 8.1 x 10 -13 ~ 8.9 x 10 -13 cm 3 ·cm / cm 2• s cm, the O2 permeability coefficient of the material at 200°C is 1.0 x 10 -12 ~ 1.9 x 10 -12 cm 3 • cm / cm 2 • s cm, the O2 permeability coefficient of the material at -20°C is 9.0 x 10 -13 ~ 9.9 x 10 -13 cm 3 • cm / cm 2 • s cm, by contrast, the sealing performance of the copolyester composite material at different temperatures has almost no obvious change, and it exhibits stable and excellent sealing performance at high and low temperatures.

[0075] The diester monomer M1 prepared from m-hydroxybenzoic acid methyl ester, the diol monomer M2 prepared from 3-hydroxy-4-methoxybenzyl alcohol and dibromoethane through coupling, and the copolyester P prepared from the diester monomer M1, the diol monomer M2 and diphenyl-4,4-dicarboxylic acid dimethyl ester through ester exchange melt polycondensation reaction have high molecular weight, good mechanical properties and thermal stability. The copolyester composite material based on m-hydroxybenzoic acid methyl ester exhibits excellent tear resistance and sealing performance, and its thermodynamic properties can also meet the application requirements. The copolyester composite material is used for preparing tear-resistant and high-sealing materials, and is applied to the sealing connection of pump equipment and parts such as centrifugal pumps and vortex pumps, the sealing of automobile engine gearbox parts, the sealing of end covers of storage containers such as towers and tanks, and the sealing connection of natural gas pipeline interfaces to ensure the safety and effectiveness of the transportation process. The prepared 5-300 μm composite film sealing material is applied to the sealing surface of electrical, mechanical and chemical equipment and parts to ensure good sealing of the composite film material to the contact surface of the equipment or parts in high-temperature or severe cold environments. In summary, the application of the "high-performance copolyester-based tear-resistant and temperature-resistant composite film sealing material" invention will have good market application prospects.

[0076] Although preferred embodiments of the application have been described, those skilled in the art will be able to make additional changes and modifications to these embodiments once they have been given the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all changes and modifications that fall within the scope of the application. Obviously, those skilled in the art can make various modifications and variations to the application without departing from the spirit and scope of the application. Thus, if these modifications and variations of the application fall within the scope of the claims of the application and their equivalents, the application is also intended to include these modifications and variations.

Claims

1. The preparation and use of a high performance copolyester based tear resistant heat resistant composite film sealing material characterized in that The preparation adopts the following process method: taking 90 parts by mass of a high-performance copolyester P based on methyl m-hydroxybenzoate, 5 parts of a tear-resistant modifier EN-01, and 5 parts of an antioxidant THP-24, mixing them uniformly in a mixer, and then extruding and granulating them through a double-screw extruder to obtain a tear-resistant and temperature-resistant composite material based on a high-performance copolyester; and finally, a melt flow and quenching process is used to prepare a high-performance copolyester-based tear-resistant and temperature-resistant composite film sealing material with a thickness of 5-300 μm; the application of a high-performance copolyester-based tear-resistant and temperature-resistant composite film sealing material, characterized in that the composite film sealing material is applied to the sealing of electrical, mechanical, and chemical equipment and instruments and their parts, and ensures good sealing of the composite film sealing material on the contact surface of the equipment or parts at a temperature not higher than 400℃ and not lower than -210℃. The structure of the high-performance copolyester P based on methyl m-hydroxybenzoate is shown in Formula I: In Formula I, m is 55-65, and n is 65-80.

2. The preparation and use of a high performance copolyester based tear resistant heat resistant composite film sealing material according to claim 1, characterized in that, The preparation of the high-performance copolyester P based on methyl m-hydroxybenzoate includes the following steps: (1) Synthesis of diester monomer M1: Synthesis of diester monomer M1: methyl m-hydroxybenzoate is added to a reactor, and tetrahydrofuran is added for stirring to dissolve it; the reactor is placed in an ice water bath, and triethylamine is added dropwise under stirring; 4,4-dichloro diphenyl ether with a CAS number of 7158-32-9 is dissolved in tetrahydrofuran, and then added to the above reactor under stirring; the molar ratio of 4,4-dichloro diphenyl ether, methyl m-hydroxybenzoate, and triethylamine is 1:(2.0-2.2):1; the mixture is continuously stirred in an ice water bath environment for 2-3 hours; after being poured into ice water and left to stand for 1 hour, solid is precipitated; the crude product of the reaction is washed with 5% sodium hydroxide aqueous solution for three times; the filtered solid is washed with distilled water until it is neutral; and the solid is dried in a 50℃ oven for 1-2 hours to obtain diester monomer M1, which has a structure shown in Formula II: (2) Synthesis of diol monomer M2 Synthesis of diol monomer M2: dibromoethane and 3-hydroxy-4-methoxybenzyl alcohol with a CAS number of 124-05-0 are added to a reactor according to a substance amount ratio of 1:(2.0-2.2); N,N-dimethylformamide is added for stirring to dissolve it; then, 1-1.2 times the substance amount of potassium carbonate is added; the reaction mixture is heated to 80℃; after continuous stirring for 2-3 hours, the solid is precipitated by pouring into ice water; the solid is filtered out and washed with distilled water until it is neutral; the solid is recrystallized with chloroform and then filtered again; and the filtered solid is dried in a 50℃ oven for 1-2 hours to obtain diol monomer M2, which has a structure shown in Formula III: (3) Preparation of high-performance copolyester P based on methyl m-hydroxybenzoate: Synthesis of the copolyester crude product: under nitrogen protection, diester monomer M1 with structural formula , diol monomer M2 with structural formula and dimethyl biphenyl-4,4-dicarboxylate with CAS number 792-74-5 were added into a reactor in a certain molar ratio, a certain mass of catalyst was added, and stirring reaction was carried out at a temperature of 220°C and under N2 atmosphere for 2 hours, after which the copolymerization reaction was carried out at a temperature of 320°C and a vacuum degree of 120-130 Pa for 1-2 hours, to obtain a copolyester crude product; Purification of the copolyester: the crude product of the copolyester is dissolved in chloroform, and the insoluble matter is filtered out; sufficient methanol is added dropwise to the clear solution until the white precipitate no longer increases; the precipitate filtered out is washed with cooled methanol for 2-3 times; the filtered solid is dried in a 50℃ oven for 1-2 hours to obtain the high-performance copolyester P based on methyl m-hydroxybenzoate.

3. The preparation of a high performance co-polyester P based on methyl meta-hydroxy benzoate according to claim 2, characterized in that: The catalyst used in the synthesis of the copolyester is one of titanium (III) chloride, bismuth (III) neodecanoate and dibutyl tin (II) oxide, and the amount of the catalyst used is 2% to 3% of the mass of the diester monomer M1.

4. A process for the preparation of a high performance co-polyester P based on methyl meta-hydroxy benzoate as claimed in claim 2, characterized in that: The ratio of the diester monomer M1 to the substance amount of the biphenyl-4,4-dicarboxylic acid dimethyl ester and the diol monomer M2 is 1:(1.0-1.2):(2.0-2.2).

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