Fluorine-containing polyester integrating high hydrophobicity, low dielectric property and flame retardance

Abstract

The invention relates to fluorine-containing polyester, in particular to fluorine-containing polyester integrating high hydrophobicity, low dielectric property and flame retardance. In order to overcome the defects that an existing flame retardant is easy to migrate and poor in durability, the dielectric constant of polyester is increased and the like, the fluorine-containing polyester is synthesized by hydroxyl-terminated binary fluorine-containing alcohol and a multi-component monomer through a direct esterification method and an ester exchange method. The invention belongs to the technical field of manufacturing of durable, low-dielectric and bulk flame-retardant polyester. The hydroxyl-terminated binary fluorine-containing alcohol is characterized in that the hydroxyl-terminated binary fluorine-containing alcohol is prepared by reducing fluorine-containing plastic and rubber after thermal oxygen alkaline hydrolysis, and has the advantages of high fluorine content and low dielectric constant, and the fluorine content of a polyester body can be effectively improved under the condition of a small addition amount; therefore, the effects of improving the durability, reducing the dielectric constant and realizing the flame-retardant effect of the body are achieved.

Description

Technical Field

[0001] The invention relates to a fluorine-containing polyester and belongs to the technical field of flame retardant manufacturing. Background Art

[0002] At present, PET film for electrical insulation has been widely used in the fields of wires and cables, transformers, motors, electronic equipment, etc. due to its excellent insulation performance, mechanical strength, heat resistance and good processability. With the development of new energy and power industries, PET film for electrical insulation will face higher technical requirements and a broader market space. Research and development directions include developing films with lower dielectric loss to improve circuit sensitivity and transmission efficiency, higher flame retardancy to improve safe use, and better weather resistance to increase its service life. However, the polarity of PET molecular structure is relatively high, so the dielectric constant is relatively high (between 3.5-4.5); PET molecules contain a large number of ester groups, and their long-term moisture and UV resistance are relatively weak; currently, PET flame retardant mostly uses external flame retardants. Since the compatibility of flame retardants with PET still needs to be improved, there is still a migration problem. After the flame retardant groups are introduced into PET by copolymerization, such as phosphorus, nitrogen and other element groups, they can indeed play a flame retardant effect and will not migrate, but the chemical bonds connecting such groups with PET are extremely unstable, which can easily cause PET degradation. Some documents and patents use fluorine-containing diacids and fluorine-containing diols, such as tetrafluoroterephthalic acid and hexafluorobutanediol. The former has a low fluorine content and has limited effect on performance changes, while the latter is an industrial-grade product and is expensive. The present invention uses a fluorine-containing diol prepared by thermal alkali oxygen degradation of industrial-grade fluororubber and fluoroplastics and copolymerizes it with other monomers of PET. The fluorine-containing diol has a low cost, a fluorine content of more than 50%, a low molecular weight, does not affect the conventional polymerization process of PET, and can be introduced into PET to effectively and at a low cost improve the durability of PET, reduce dielectric properties, and improve permanent flame retardancy. Summary of the invention

[0003] The present invention aims to solve the problem that the existing flame retardants use fluorine-containing diacids and fluorine-containing diols, such as tetrafluoroterephthalic acid and hexafluorobutanediol, etc. The former has a low fluorine content and has limited effect on performance changes, while the latter is an industrial-grade product with high prices. A fluorine-containing polyester with high hydrophobicity, low dielectric and flame retardancy is proposed.

[0004] The technical solution adopted by the present invention to solve the above problems is: the fluorine-containing polyester of the present invention is synthesized from binary fluorine-containing alcohol and multi-component monomers through direct esterification and ester exchange.

[0005] Further, the direct esterification method comprises:

[0006] Step 1: synthesize the materials in a reactor, and preheat the reactor for 30 minutes before adding the materials;

[0007] Step 2: Under a nitrogen atmosphere, add all the mixed monomer raw materials with a molar ratio of 1:1 into a reaction kettle, and increase the temperature until the raw materials are evenly mixed;

[0008] Step 3, adding a catalyst, a water-carrying agent and an antioxidant, gradually increasing the temperature, maintaining the pressure, ensuring that the by-products can be discharged smoothly under the action of the condensation equipment, until no by-products are discharged after the temperature is increased for 20 minutes, stopping the reaction, and releasing the pressure in the reactor to normal pressure;

[0009] Step 4: Use nitrogen to press out the final product, and after pelletizing and drying, a fluorine-containing polyester material with multiple functions in one can be obtained.

[0010] Further, the transesterification method comprises:

[0011] Step 1: synthesize the materials in a reactor, and preheat the reactor for 30 minutes before adding the materials;

[0012] Step 2: Add mixed monomer, water-carrying agent and catalyst in proportion under nitrogen atmosphere, wherein the molar ratio of alcohol to acid in the mixed monomer is 1:1.2;

[0013] Step 3: Raise the temperature and pressure until the by-products can be discharged smoothly from the condenser;

[0014] Step 4: Maintain the temperature and pressure until no liquid is discharged within 30 minutes, open the reactor and release the internal pressure to normal pressure;

[0015] Step 5, continue the reaction at normal pressure and temperature for 30 minutes and then add an antioxidant;

[0016] Step 6: Turn on the vacuum pump and gradually reduce the pressure to below 60 Pa within 2 hours until liquid precipitates out of the condenser. Continue the reaction until the power of the reactor reaches 40 W and then stop the reaction.

[0017] Step 7: Return the internal pressure to normal pressure, press out the final product with nitrogen, pelletize and dry to obtain a multifunctional fluorine-containing polyester material.

[0018] Furthermore, the binary fluorine-containing alcohol is a fluorine-containing diol obtained by reducing fluorine-containing elastomer, fluorine-containing rubber and fluorine-containing plastic through thermal alkali oxidation degradation, and the number average molecular weight Mn is between 800 and 2000.

[0019] Furthermore, the polymonomers are dibasic acids and acid anhydrides.

[0020] Furthermore, the catalyst is one of an organic tin catalyst and a Lewis acid catalyst, wherein the general formula of the organic tin catalyst is RnSnX4-n, wherein n=1 to 4, and R is an alkyl group or an aromatic group.

[0021] Furthermore, the antioxidant is one or more of a phenolic antioxidant, an amine antioxidant and an ester antioxidant.

[0022] The beneficial effects of the present invention are as follows: the present invention introduces fluorine-containing segments into the polyester main chain by a polymerization method, thereby effectively improving the hydrophobicity of the fluorine-containing polyester, while reducing the dielectric constant of the material and improving the flame retardant performance of the polyester. DETAILED DESCRIPTION

[0023] Specific implementation method 1: A fluorine-containing polyester with high hydrophobicity, low dielectric and flame retardancy, wherein the fluorine-containing polyester is synthesized from a binary fluorine-containing alcohol and a multi-component monomer by direct esterification and ester exchange.

[0024] Wherein, the direct esterification method comprises:

[0025] Step 1: synthesize the materials in a reactor, and preheat the reactor for 30 minutes before adding the materials;

[0026] Step 2: Under a nitrogen atmosphere, add all the mixed monomer raw materials with a molar ratio of 1:1 into a reaction kettle, and increase the temperature until the raw materials are evenly mixed;

[0027] Step 3, adding a catalyst, a water-carrying agent and an antioxidant, gradually increasing the temperature, maintaining the pressure, ensuring that the by-products can be discharged smoothly under the action of the condensation equipment, until no by-products are discharged after the temperature is increased for 20 minutes, stopping the reaction, and releasing the pressure in the reactor to normal pressure;

[0028] Step 4: Use nitrogen to press out the final product, and after pelletizing and drying, a fluorine-containing polyester material with multiple functions in one can be obtained.

[0029] The transesterification method comprises:

[0030] Step 1: synthesize the materials in a reactor, and preheat the reactor for 30 minutes before adding the materials;

[0031] Step 2: Add mixed monomer, water-carrying agent and catalyst in proportion under nitrogen atmosphere, wherein the molar ratio of alcohol to acid in the mixed monomer is 1:1.2;

[0032] Step 3: Raise the temperature and pressure until the by-products can be discharged smoothly from the condenser;

[0033] Step 4: Maintain the temperature and pressure until no liquid is discharged within 30 minutes, open the reactor and release the internal pressure to normal pressure;

[0034] Step 5, continue the reaction at normal pressure and temperature for 30 minutes and then add an antioxidant;

[0035] Step 6: Turn on the vacuum pump and gradually reduce the pressure to below 60 Pa within 2 hours until liquid precipitates out of the condenser. Continue the reaction until the power of the reactor reaches 40 W and then stop the reaction.

[0036] Step 7: Return the internal pressure to normal pressure, press out the final product with nitrogen, pelletize and dry to obtain a multifunctional fluorine-containing polyester material.

[0037] The binary fluorine-containing alcohol is a fluorine-containing diol obtained by reducing fluorine-containing elastomer, fluorine-containing rubber and fluorine-containing plastic through thermal alkali oxidation degradation, and the number average molecular weight Mn is between 800 and 2000.

[0038] The polymonomers are dibasic acids and acid anhydrides.

[0039] The catalyst is one of an organic tin catalyst and a Lewis acid catalyst, wherein the general formula of the organic tin catalyst is RnSnX4-n, wherein n=1-4, and R is an alkyl group or an aromatic group.

[0040] Among them, the reactor has a separate condensing device with a collector; the reactor has a controllable vacuum system that can pressurize and depressurize the inside of the system; and the reactor has a separate vent that can control the internal gas atmosphere; and the reactor has a feeding port at the top and a discharging port at the bottom; and the reactor has a stirring power display system.

[0041] Example

[0042] Example 1

[0043] Ethylene glycol, difluoro alcohol and terephthalic acid are used as raw materials, mixed in proportion, and fed at a molar ratio of terephthalic acid / difluoro alcohol / ethylene glycol of 1 / 0.1 / 1.3. The polymerization reaction is divided into esterification and polycondensation processes. The esterification reaction is carried out under nitrogen protection and a pressure of 0.4MPa. Terephthalic acid and ethylene glycol undergo an esterification reaction to form a prepolymer. The reaction temperature is 220°C and the reaction time is 3h. The polycondensation reaction is firstly carried out at high temperature and normal pressure, the reaction temperature is 260°C, and the reaction time is maintained for 3h; then, the post-polycondensation is carried out under high temperature and high vacuum conditions, the vacuum degree is lower than 60Pa, the reaction temperature is 270°C, and the material is discharged under reduced pressure when the torque reaches a predetermined value.

[0044] Example 2

[0045] Ethylene glycol, difluoro alcohol and terephthalic acid are used as raw materials, mixed in proportion, and fed at a molar ratio of terephthalic acid / difluoro alcohol / ethylene glycol of 1 / 0.2 / 1. The polymerization reaction is divided into esterification and polycondensation processes. The esterification reaction is carried out under nitrogen protection and a pressure of 0.4MPa. Terephthalic acid and ethylene glycol undergo esterification reaction to form a prepolymer. The reaction temperature is 220°C and the reaction time is 3h. The polycondensation reaction is firstly carried out at high temperature and normal pressure, the reaction temperature is 260°C, and the reaction time is maintained for 3h; then, the post-polycondensation is carried out at high temperature and high vacuum conditions, the vacuum degree is lower than 60Pa, the reaction temperature is 270°C, and the material is discharged under reduced pressure when the torque reaches a predetermined value.

[0046] Example 3

[0047] Ethylene glycol, difluoro alcohol and terephthalic acid are used as raw materials, mixed in proportion, and fed according to the molar ratio of terephthalic acid / difluoro alcohol / ethylene glycol of 1 / 0.3 / 0.9. The polymerization reaction is divided into esterification and polycondensation processes. The esterification reaction is carried out under nitrogen protection and at a pressure of 0.4MPa. Terephthalic acid and ethylene glycol undergo esterification reaction to form a prepolymer. The reaction temperature is 220℃ and the reaction time is 3h. The polycondensation reaction is firstly carried out at high temperature and normal pressure, at a reaction temperature of 260℃ and maintained for 3h; then, the post-polycondensation is carried out under high temperature and high vacuum conditions, at a vacuum degree of less than 60Pa and a reaction temperature of 270℃. When the torque reaches a predetermined value, the material is discharged under reduced pressure.

[0048] From the performance comparison in Table 1, it can be seen that adding fluorinated diols obtained by degradation and reduction of fluororubber and fluoroplastics can significantly improve the hydrophobicity of PET, thereby improving its weather resistance, significantly reduce the dielectric constant, and improve the flame retardant properties of PET, even at a very small addition amount.

[0049] Table 1 Performance comparison between fluorinated PET and PET

[0050]

[0051]

[0052] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A fluorinated polyester having high hydrophobicity, low dielectric and flame retardancy, characterized in that: The fluorine-containing polyester is synthesized from binary fluorine-containing alcohol and multi-monomers through direct esterification and ester exchange.

2. The fluorinated polyester having high hydrophobicity, low dielectric and flame retardancy according to claim 1, characterized in that: The direct esterification method comprises: Step 1: synthesize the materials in a reactor, and preheat the reactor for 30 minutes before adding the materials; Step 2: Under a nitrogen atmosphere, add all the mixed monomer raw materials with a molar ratio of 1:1 into a reaction kettle, and increase the temperature until the raw materials are evenly mixed; Step 3, adding a catalyst, a water-carrying agent and an antioxidant, gradually increasing the temperature, maintaining the pressure, ensuring that the by-products can be discharged smoothly under the action of the condensation equipment, until no by-products are discharged after the temperature is increased for 20 minutes, stopping the reaction, and releasing the pressure in the reactor to normal pressure; Step 4: Use nitrogen to press out the final product, and after pelletizing and drying, a fluorine-containing polyester material with multiple functions in one can be obtained.

3. The fluorinated polyester with high hydrophobicity, low dielectric and flame retardancy according to claim 1, characterized in that: The transesterification method comprises: Step 1: synthesize the materials in a reactor, and preheat the reactor for 30 minutes before adding the materials; Step 2: Add mixed monomer, water-carrying agent and catalyst in proportion under nitrogen atmosphere, wherein the molar ratio of alcohol to acid in the mixed monomer is 1:1.2; Step 3: Raise the temperature and pressure until the by-products can be discharged smoothly from the condenser; Step 4: Maintain the temperature and pressure until no liquid is discharged within 30 minutes, open the reactor and release the internal pressure to normal pressure; Step 5, continue the reaction at normal pressure and temperature for 30 minutes and then add an antioxidant; Step 6: Turn on the vacuum pump and gradually reduce the pressure to below 60 Pa within 2 hours until liquid precipitates out of the condenser. Continue the reaction until the power of the reactor reaches 40 W and then stop the reaction. Step 7: Return the internal pressure to normal pressure, press out the final product with nitrogen, pelletize and dry to obtain a multifunctional fluorine-containing polyester material.

4. The fluorinated polyester with high hydrophobicity, low dielectric and flame retardancy according to claim 1, characterized in that: The binary fluorine-containing alcohol is a fluorine-containing diol obtained by reducing fluorine-containing elastomer, fluorine-containing rubber and fluorine-containing plastic through thermal alkali oxidation degradation, and the number average molecular weight Mn is between 800 and 2000.

5. The fluorine-containing polyester with high hydrophobicity, low dielectric and flame retardancy according to claim 1, characterized in that: The polymonomers are dibasic acids and acid anhydrides.

6. A fluorine-containing polyester with high hydrophobicity, low dielectric and flame retardancy according to claim 2 or 3, characterized in that: The catalyst is one of an organic tin catalyst and a Lewis acid catalyst, wherein the general formula of the organic tin catalyst is RnSnX4-n, wherein n=1-4, and R is an alkyl group or an aromatic group.

7. A fluorine-containing polyester with high hydrophobicity, low dielectric and flame retardancy according to claim 2 or 3, characterized in that: The antioxidant is one or more of phenolic antioxidants, amine antioxidants and ester antioxidants.

Images