CN105524546A - Polyimide paint for enameled wire with high heat resistant grade - Google Patents

Abstract

The invention discloses a polyimide paint for enameled wire with high heat-resistant grade and a preparation method thereof. Diamine monomers including 1,3-bis(3-aminophenoxy)benzene are stirred and dissolved in a strong pole in a non-protic solvent, and then add dianhydride monomers including 1,2-bis(3,4-dicarboxyphenoxy)phthalic anhydride in batches, stir and dissolve in an ice-water bath at 5-10°C, After 3-5 hours of polymerization reaction, add an end-capping agent containing unsaturated groups and react for 2-5 hours to obtain the polyimide paint. The preparation method of the invention is simple, and the prepared paint liquid has high temperature-resistant grade and low apparent viscosity, and is suitable for the production of polyimide enameled wire above grade 250.

Description

A kind of polyimide varnish for enameled wire with high heat resistance grade

technical field

The invention relates to the field of preparation of polymer coating materials, in particular to a preparation method of polyimide paint for high temperature resistant enameled wires.

Background technique

Enameled wire varnish is an insulating material commonly used in electrical appliances. It is coated on the outside of bare wires during use. After curing, it is wound into a coil, and each turn of wire is then dipped in bonding resin to form an enameled wire. The heat resistance of wire enamel is directly related to the technical indicators and operating life of electrical equipment (Fan Liangzi, Yu Xinhai, Wu Shuang, etc., Insulation Materials, 2012, 45(1): p.30-33). Especially in recent years, motors and appliances are developing toward smaller size and higher power, which makes the coil generate more heat during motion, so the requirements for the heat resistance level of insulating materials are getting higher and higher.

Polyimide enameled wire is currently the most heat-resistant organic polymer enameled wire, which can meet the requirements of long-term use at 220°C. Polyimide wire enamel has excellent comprehensive properties and is the main variety of 240-grade high temperature resistant wire enamel in the world. It has good heat resistance and mechanical properties at the same time, and it also performs excellent in chemical corrosion resistance and freezing resistance. At present, in my country's enameled wire market, 240-grade aromatic polyimide enameled wire is the enameled wire with the highest heat resistance level. Patent CN202749117U discloses a polyimide enameled wire, that is, the outer surface of the conductor is evenly coated with polyimide insulating paint film, and the obtained enameled wire can work in a high temperature environment with a temperature of about 240 °C for a long time, and can be used as a nuclear power motor , oil drilling motors, explosion-proof motors and other insulated winding wires. Sun Fei et al. (Sun Fei, Sun Xuyang, Qi Shengli, Tian Guofeng, Wu Dezhen, China Plastics, 2014, 28(1): p.24-37) used 3,3',4,4'-biphenyltetracarboxylic acid di Preparation of polyamide by blending anhydride/4,4'-diaminodiphenyl ether (BPDA/ODA) and pyromellitic dianhydride/4,4'-diaminodiphenyl ether (PMDA/ODA) polyamic acid Imine film, the film can maintain good mechanical properties, and its elongation at break will be significantly improved under a suitable blending ratio, while still maintaining its good heat resistance, and the dielectric loss temperature rises sharply at 250 ℃ and above, it is expected to be widely used in the production of enameled wire above 240 grade.

Patent CN103965770A mixes polyamic acid solution and chain-extended bismaleimide prepolymer solution in proportion, adds organic solvent to adjust the solid content and viscosity of the paint solution, and obtains wine red transparent viscous polyimide wire enamelled varnish . The enameled wire enamel has good storage stability, and its high temperature resistance, softening breakdown temperature and breakdown voltage are significantly higher than the national standard of 240-grade polyimide enamelled round copper wire, and can be used for high-load, high-power, refrigerant-resistant motors Insulation, the market prospect is broad. The patent CN103102796A relates to a benzimidazole-type polyimide wire enamel and its preparation method. The obtained product has excellent comprehensive performance and has a good application prospect.

However, after research, it is found that the current polyimide wire enamel has the following problems: (1) the solid content of the paint liquid is low, and the apparent viscosity is large, which increases the difficulty of coating during enameled wire production; (2) the enameled wire enamel contains toxic Solvents pollute the environment; (3) At present, polyimide enameled wires cannot be used for a long time at a temperature above 240°C.

Contents of the invention

The purpose of the present invention is to provide a polyimide paint for enameled wires with heat resistance grade above 250 and low apparent viscosity.

The technical solution to realize the object of the present invention is: a kind of polyimide varnish for enameled wire of high heat-resistant grade, comprises the following steps: the diamine monolayer that comprises 1,3-bis(3-aminophenoxy)benzene Stir and dissolve the body in a strong polar aprotic solvent, then add dianhydride monomers including 1,2-bis(3,4-dicarboxyphenoxy)phthalic anhydride in batches, at 5-10°C Stir and dissolve in an ice-water bath, polymerize for 3-5 hours, then add an end-capping agent containing an unsaturated group and react for 2-5 hours to obtain the polyimide paint.

Further, the end-capping agent is selected from one or more of p-aminostyrene, 4-phenylethynylphthalic anhydride, norbornene anhydride, and 3-phenylethynylaniline.

Further, diamine monomers also include 4,4'-diaminodiphenylmethane, 4,4'-diaminobiphenyl, p-phenylenediamine, m-phenylenediamine, 33'-dimethyl-4, 4'-Diaminodiphenylmethane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 4,4'-bis(4-aminophenoxy)benzophenone, 4 ,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 1,4-bis(3-aminophenoxy)benzene, 2,2 - One or more of bis[4-(4-aminophenoxy)phenyl]propane.

Further, dianhydride monomers also include pyromellitic dianhydride, 3,3',4,4'-tetracarboxylic biphenyl dianhydride, 3,3',4,4'-tetracarboxylic benzophenone dianhydride , 3,3',4,4'-tetracarboxylic diphenyl ether dianhydride, 1,4-bis(3,4-dicarboxylic acid phenoxy)phthalic anhydride, 1,3-bis(3,4- One or more of dicarboxylic acid phenoxy) phthalic anhydrides.

Further, the mole fraction of 1,2-bis(3,4-dicarboxyphenoxy)phthalic anhydride in the dianhydride monomer is not less than 55%.

Further, the mole fraction of 1,3-bis(3-aminophenoxy)benzene in the diamine monomer is not less than 60%.

Further, the molar ratio of the dianhydride monomer to the diamine monomer is 0.95-1.03:1.

Further, the amount of the end-capping agent is 0.5-2% of the total moles of the dianhydride monomers, more preferably 1.0-1.5% of the total moles of the dianhydride monomers.

Further, the number of batches is not less than 6 times.

The solid content of the polyimide paint prepared by the present invention is controlled between 17-25%, more preferably the solid content is controlled at 20-22%.

Gained polyimide paint of the present invention has following beneficial effect:

1) The temperature index of the obtained enameled wire can reach more than 250 grades, and the highest can reach 270 grades.

2) The apparent viscosity of the paint liquid is low, between 2000 and 4000 centipoise, which greatly reduces the difficulty of coating when producing enameled wires.

3) The preparation method is simple and meets the requirements of environmental protection.

detailed description

The implementation method of the present invention is described below with specific examples. It should be noted that the present invention is not limited to the scope of the examples.

Example 1

In a reactor equipped with a thermometer and mechanical stirring, under the condition of not higher than 30°C, add 0.60mol of 1,3-bis(4-aminophenoxy)benzene, 0.20mol of 4,4'-diamino Diphenyl ether and 0.20mol of p-phenylenediamine were dissolved in N,N-dimethylacetamide, then the temperature was lowered to 10°C, and 0.56mol of 1,2-bis(3 , 4-dicarboxyphenoxy) phthalic anhydride, 0.435mol of pyromellitic dianhydride, reacted for 1 hour, then added 0.01mol of 4-phenylethynylphthalic anhydride, and reacted for 3 hours to obtain the present invention. The polyimide paint described above. Stir continuously during the whole process, and the solid content of the final solution is controlled at 20%.

Example 2

In a reactor equipped with a thermometer and mechanical stirring, 0.70 mol of 1,3-bis(4-aminophenoxy)benzene, 0.20 mol of m-phenylenediamine and 0.10 mol of 2,2-bis[4-(3-aminophenoxy)phenyl]propane was dissolved in N,N-dimethylacetamide, then the temperature was lowered to 10°C, and added in 7 times within 2 hours 0.65mol of 1,2-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 0.344mol of 3,3',4,4'-tetracarboxylic biphenyldianhydride, reacted for 1 hour, then added 0.012mol of 3-phenylacetylene aniline was reacted for another 3 hours to obtain the polyimide paint of the present invention. Stir continuously during the whole process, and the solid content of the final solution is controlled at 20%.

Example 3

In a reactor equipped with a thermometer and mechanical stirring, under the condition of not higher than 30°C, add 0.80mol of 1,3-bis(4-aminophenoxy)benzene, 0.20mol of 4,4'-diamino Diphenyl ether was dissolved in N-methylpyrrolidone, then the temperature was lowered to 10°C, and 0.74mol of 1,2-bis(3,4-dicarboxyphenoxy)phthalic anhydride was added in 7 times within 2 hours , 0.13mol of 3,3',4,4'-tetracarboxylic diphenyl ether dianhydride and 0.123mol of pyromellitic dianhydride were reacted for 1 hour, then 0.014mol of norbornene anhydride was added and reacted for another 3 hours , to obtain the polyimide paint of the present invention. Stir continuously during the whole process, and the solid content of the final solution is controlled at 20%.

Example 4

In a reactor equipped with a thermometer and mechanical stirring, 0.90 mol of 1,3-bis(4-aminophenoxy)benzene, 0.07 mol of 2,2-bis(3 -Amino-4-aminophenyl)propane and 0.03mol of 4,4'-bis(4-aminophenoxy)benzophenone were dissolved in N,N-dimethylacetamide, and then the temperature was lowered to 10°C, add 0.80 mol of 1,2-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 0.20 mol of 3,3',4,4'-tetracarboxylic acid di Benzophenone dianhydride was reacted for 1 hour, followed by adding 0.015 mol of 4-phenylethynylphthalic anhydride, and reacted for another 3 hours to obtain the polyimide paint of the present invention. Stir continuously during the whole process, and the solid content of the final solution is controlled at 20%.

Example 5

In a reactor equipped with a thermometer and mechanical stirring, under the condition of not higher than 30°C, add 0.95mol of 1,3-bis(4-aminophenoxy)benzene, 0.05mol of 4,4'-diamino Diphenyl ether was dissolved in N-methylpyrrolidone, then the temperature was lowered to 10°C, and 0.87mol of 1,2-bis(3,4-dicarboxyphenoxy)phthalic anhydride was added in 7 times within 2 hours , 0.05mol of pyromellitic dianhydride, 0.05mol of 3,3',4,4'-tetracarboxylic benzophenone dianhydride, 0.06mol of 3,3',4,4'-tetracarboxylic biphenyl diphenyl The anhydride was reacted for 1 hour, followed by adding 0.01 mol of 3-phenylacetylene aniline, and then reacted for 3 hours to obtain the polyimide paint of the present invention. Stir continuously during the whole process, and the solid content of the final solution is controlled at 20%.

Performance Test of Polyimide Wire Enamel

The viscosity of the obtained polyimide paint was tested at 25°C with a digital viscometer produced by Shanghai Nirun Intelligent Technology Co., Ltd. The viscosity of the paint solution of Examples 1-5 was tested, and the results are shown in Table 1.

Table 1 Viscosity of paint liquid

Example Viscosity (cp) 1 3670 2 3556 3 3574 4 3492 5 3779

A round copper wire with a diameter of 0.5mm was used to prepare enameled wire on a horizontal enameled wire machine. The wind speed of the circulating fan is 3000 rpm, the furnace temperature is raised to 460°C, and the wire is released, continuously annealed and softened, the felt is baked and solidified after painting, the blower is forced to take up the wire with cold air, and the thickness of the paint film is 0.025mm.

According to GB/T6109.22QY-1/240, the enameled wire properties of the wire enameled wire varnishes of Examples 1-5 prepared by the method of this example were tested, and the test results are shown in Table 2.

Table 2 Performance Test

Claims (10)

1. a polyimide varnish for high heat-resistant grade enameled wire, is characterized in that, comprises the steps: will comprise 1,3-bis(3-aminophenoxy) benzene is stirred and dissolved in the diamine monomer In a strong polar aprotic solvent, then add dianhydride monomers including 1,2-bis(3,4-dicarboxyphenoxy)phthalic anhydride in batches, and stir in an ice-water bath at 5-10°C After dissolving and polymerizing for 3-5 hours, add an end-capping agent containing an unsaturated group and react for 2-5 hours to obtain the polyimide paint. 2. the polyimide varnish for high heat-resistant grade enameled wire as claimed in claim 1, is characterized in that, described end-capping agent is selected from p-aminostyrene, 4-phenylethynyl phthalic anhydride, norbornene anhydride, One or more of 3-phenylacetylene anilines. 3. The polyimide varnish for high heat-resistant enameled wire as claimed in claim 1, wherein the diamine monomer also includes 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane Biphenyl, p-phenylenediamine, m-phenylenediamine, 33'-dimethyl-4,4'-diaminodiphenylmethane, 2,2-bis[4-(3-aminophenoxy)phenyl] Propane, 4,4'-bis(4-aminophenoxy)benzophenone, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether One or more of diphenyl ether, 1,4-bis(3-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane. 4. The polyimide paint for high heat-resistant enameled wire as claimed in claim 1, wherein the dianhydride monomer also includes pyromellitic dianhydride, 3,3',4,4'-tetracarboxylic acid Biphenyl dianhydride, 3,3',4,4'-tetracarboxylic benzophenone dianhydride, 3,3',4,4'-tetracarboxylic diphenyl ether dianhydride, 1,4-bis(3,4 -One or more of dicarboxylic acid phenoxy)phthalic anhydride and 1,3-bis(3,4-dicarboxylic acid phenoxy)phthalic anhydride. 5. The polyimide varnish for high heat-resistant grade enameled wire as claimed in claim 1, is characterized in that, 1,2-two (3,4-dicarboxyphenoxy) phthalic anhydride in the dianhydride monomer Mole fraction of not less than 55%. 6. The polyimide varnish for high heat-resistant enameled wire as claimed in claim 1, wherein the molar fraction of 1,3-bis(3-aminophenoxy)benzene in the diamine monomer is not low at 60%. 7. The polyimide varnish for high heat-resistant enameled wires according to claim 1, characterized in that the molar ratio of dianhydride monomers to diamine monomers is 0.95-1.03:1. 8. The polyimide varnish for high heat-resistant enameled wire according to claim 1, wherein the amount of the end-capping agent is 0.5-2% of the total moles of dianhydride monomers. 9. The polyimide paint for high heat-resistant grade enameled wire as claimed in claim 1, characterized in that, the number of batches is not less than 6 times. 10. The preparation method of the polyimide varnish for high heat-resistant enameled wire as described in any one of claims 1-9.