Corona-resistant, high-wear-resistant modified polyimide insulating paint and preparation method thereof

Abstract

The present application relates to the technical field of insulating paint, in particular to a corona-resistant and high-wear-resistant modified polyimide insulating paint and a preparation method thereof. The corona-resistant and high-wear-resistant modified polyimide insulating paint comprises a polyamide acid resin and nano inorganic particles; the polyamide acid resin is synthesized from a dianhydride and a diamine, and the diamine includes a diamine containing a POSS structure and an aromatic diamine. The polyimide insulating paint prepared by the present application has the characteristics of corona resistance, high adhesion and high wear resistance, and can be used as an insulating paint for special motors and remains stable during long-time operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of insulating paint, in particular to a corona-resistant and high-wear-resistant modified polyimide insulating paint and a preparation method thereof. BACKGROUND

[0002] As the insulating paint of special motor, it needs to maintain stability in long time work, especially in some extreme environments, so it puts forward very high requirements for its long-term wear resistance. Polyimide has excellent thermodynamic properties. However, the friction coefficient and wear rate of polyimide are large, which greatly limits its long-term application in the field of special motor. Most of the existing reports on polyimide insulating paint are from the research on improving its heat resistance, mechanical properties and corona resistance, but there are few reports on the improvement of the large friction coefficient and high wear rate of polyimide in the field of insulating paint.

[0003] The patent technology document CN116179075A discloses a preparation method of POSS modified polyimide insulating paint. The raw materials of the insulating paint include: a resin containing a polyimide or a polyamide acid structure, a POSS modifier and nano inorganic particles, wherein the POSS modifier is a cage-shaped silsesquioxane with a single amino group. The POSS modified polyimide insulating paint of the application not only retains the advantages of polyimide, but also improves the corona resistance as an insulating paint. However, the cage-shaped silsesquioxane with a single amino group is only grafted at both ends of the polyimide chain, and the grafting amount is low, which is difficult to fully play the role of POSS in polyimide. Moreover, the patent does not mention the role of POSS-containing polyimide in improving wear resistance. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a corona-resistant and high-wear-resistant modified polyimide insulating paint and a preparation method thereof, so as to improve the large friction coefficient and high wear rate of polyimide in the field of insulating paint, and at the same time have corona resistance and high adhesion.

[0005] In order to achieve the above purpose, the present application provides a corona-resistant and high-wear-resistant modified polyimide insulating paint, which is characterized by comprising a polyamide acid resin and nano inorganic particles; the polyamide acid resin is synthesized by a dianhydride and a diamine, and the diamine includes a diamine containing a POSS structure and an aromatic diamine.

[0006] Further, the molar ratio of the dianhydride and the diamine is 0.8-1.1:1.

[0007] Further, the molar ratio of the diamine containing a POSS structure and the aromatic diamine is 0.1-0.2:1.

[0008] Further, the dianhydride is selected from one or more of the group consisting of pyromellitic dianhydride, cyclobutane tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, and bisphenol A type diether dianhydride.

[0009] Further, the POSS structure containing diamine is a mixture of Formula I and Formula II at a molar ratio of 1:0.5-1.

[0010]

[0011] Further, the aromatic diamine is selected from one or more of the group consisting of 4,4'-diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 4,4'-diaminobenzanilide.

[0012] Further, the nano inorganic particle contains MoS2 nanoparticles with a size of 1-100 nm.

[0013] Preferably, the content of the MoS2 nanoparticles is 0.1-30 wt% of the polyamic acid resin.

[0014] Further, the nano inorganic particle further contains one or more of the group consisting of an auxiliary modified silicon dioxide, an auxiliary modified titanium dioxide, and an auxiliary modified aluminum trioxide.

[0015] Further, the auxiliary is selected from one or more of the group consisting of polymethylphenyl acrylate, polyvinyl alcohol, polycarbonate, and polyvinyl acetonitrile.

[0016] Preferably, the auxiliary is polyvinyl alcohol.

[0017] Preferably, the molecular weight of the polyvinyl alcohol is 1000-10000.

[0018] Further, the preparation method of the auxiliary modified silicon dioxide is as follows: first, modify the silicon dioxide with a silane coupling agent, and then mix it with polyvinyl alcohol.

[0019] Further, the polyamic acid resin is synthesized in an organic solvent.

[0020] Preferably, the organic solvent is selected from one or more of the group consisting of N-methylpyrrolidone, N,N'-dimethylacetamide, N,N'-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, propylene glycol methyl ether acetate, propylene glycol diacetate, ethylene glycol monomethyl ether acetate, and ethylene glycol monoethyl ether acetate.

[0021] Further, the application also provides a preparation method of the above-mentioned corona-resistant and high-wear-resistant modified polyimide insulating paint, comprising the following steps:

[0022] (1) mixing and stirring a dianhydride and a diamine in an organic solvent to obtain a POSS-modified polyamic acid resin;

[0023] (2) adding nano inorganic particles to the POSS-modified polyamic acid resin and fully stirring to obtain the corona-resistant and high-wear-resistant modified polyimide insulating paint.

[0024] Further, the application also provides an application of the above-mentioned corona-resistant and high-wear-resistant modified polyimide insulating paint, which is used for preparing an electromagnetic wire in an electric vehicle or a high-voltage driving motor.

[0025] Preferably, the use method of the insulating paint is to coat the insulating paint on the surface of a copper wire, to cure at 100-500 DEG C for 1-5 h, and to form an insulating layer with a polyimide structure with a thickness of 10-500 microns.

[0026] The application has the following beneficial effects:

[0027] The polyimide insulating paint prepared by the application has the characteristics of corona resistance, high adhesion and high wear resistance, the diamine with the POSS structure is used as a polyimide synthesis monomer, the dielectric property and voltage resistance of the polyimide insulating paint are effectively improved, the polyimide insulating paint further has excellent corona resistance, and the POSS structure also helps to improve the adhesion and wear resistance and mechanical property.

[0028] The application further introduces the POSS structure into the main chain and the side chain of the polyimide, the POSS on the main chain and the POSS on the side chain synergistically improve the wear resistance, and the wear rate of the polyimide insulating paint with the POSS structure on the main chain or the side chain alone is greatly reduced.

[0029] The application further introduces the MoS2 nano particles into the polyimide insulating paint, and the synergistic effect of the POSS structure and the MoS2 can effectively improve the adhesion and wear resistance of the paint film.

[0030] The application further introduces the modified silica particles and other particles into the polyimide insulating paint, effectively improves the corona resistance of the paint film, the silica nano particles and other nano particles can also be directly introduced by physical blending, but the electrostatic effect and van der Waals force between the inorganic particles make the solution stability poor, and the corona resistance is affected, the modified silica nano particles in the solution can make the compatibility between the components in the insulating paint better, the storage is more stable, and the excellent corona resistance is provided. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with specific examples.

[0032] The molecular formula of the diamine A containing the POSS structure in the present application is:

[0033]

[0034] The molecular formula of the diamine B containing the POSS structure is:

[0035]

[0036] Preparation Example 1: Preparation of polyvinyl alcohol modified silica nanoparticles

[0037] 10 g of 50 nm silica nanoparticles were dispersed in 30 g of ethanol and 70 g of deionized water, uniformly dispersed, then 0.5 g of silane coupling agent KH-570 was added, heated to 60°C, stirred for 5 h, then 5 g of polyvinyl alcohol with a molecular weight of 5000 was added, uniformly dispersed, and dried to obtain polyvinyl alcohol modified silica nanoparticles.

[0038] Example 1: Preparation of corona-resistant and high-wear-resistant modified polyimide insulating paint

[0039] (1) 0.009 mol of diamine A containing the POSS structure and 0.091 mol of 4,4'-diamino diphenyl ether were added to 130 g of N,N'-dimethylacetamide, stirred at 45°C for 20 min, then 0.04 mol of pyromellitic dianhydride was added, stirred at 35°C for 45 min, then 0.04 mol of pyromellitic dianhydride was added again, stirred at 65°C for 4 h, then heated to 85°C and stirred for 45 min to obtain a polyamic acid resin;

[0040] (2) 0.1 g of MoS2 nanoparticles with a particle size of 50 nm was added to 100 g of the polyamic acid resin, stirred at room temperature for 30 min to obtain a corona-resistant and high-wear-resistant modified polyimide insulating paint.

[0041] Example 2: Preparation of corona-resistant and high-wear-resistant modified polyimide insulating paint

[0042] (1) 0.012 mol of diamine A containing the POSS structure and 0.088 mol of 4,4'-diamino diphenyl ether were added to 150 g of N,N'-dimethylacetamide, stirred at 50°C for 15 min, then 0.045 mol of pyromellitic dianhydride was added, stirred at 40°C for 30 min, then 0.045 mol of pyromellitic dianhydride was added again, stirred at 70°C for 3 h, then heated to 90°C and stirred for 30 min to obtain a polyamic acid resin;

[0043] (2) In 100 g of the polyamic acid resin, 5 g of MoS2 nanoparticles with a particle size of 50 nm were added, and stirred at room temperature for 30-45 min to obtain a corona-resistant and high-wear-resistant modified polyimide insulating paint.

[0044] Example 3: Preparation of a corona-resistant and high-wear-resistant modified polyimide insulating paint:

[0045] (1) 0.017 mol of POSS-structured diamine A and 0.083 mol of 4,4'-oxydianiline were added to 140 g of N,N'-dimethylacetamide, stirred at 50°C for 20 min, then 0.055 mol of pyromellitic dianhydride was added, stirred at 40°C for 45 min, then 0.055 mol of pyromellitic dianhydride was added again, stirred at 70°C for 4 h, then the temperature was raised to 90°C, and stirred for 45 min to obtain a polyamic acid resin;

[0046] (2) In 100 g of the polyamic acid resin, 5 g of MoS2 nanoparticles with a particle size of 50 nm and 5 g of polyvinyl alcohol-modified silica nanoparticles prepared in Preparation Example 1 were added, and stirred at room temperature for 30-45 min to obtain a corona-resistant and high-wear-resistant modified polyimide insulating paint.

[0047] Example 4: Preparation of a corona-resistant and high-wear-resistant modified polyimide insulating paint:

[0048] (1) 0.012 mol of POSS-structured diamine B and 0.088 mol of 4,4'-oxydianiline were added to 150 g of N,N'-dimethylacetamide, stirred at 50°C for 15 min, then 0.045 mol of pyromellitic dianhydride was added, stirred at 40°C for 30 min, then 0.045 mol of pyromellitic dianhydride was added again, stirred at 70°C for 3 h, then the temperature was raised to 90°C, and stirred for 30 min to obtain a polyamic acid resin;

[0049] (2) In 100 g of the polyamic acid resin, 5 g of MoS2 nanoparticles with a particle size of 50 nm were added, and stirred at room temperature for 30-45 min to obtain a corona-resistant and high-wear-resistant modified polyimide insulating paint.

[0050] Example 5: Preparation of a corona-resistant and high-wear-resistant modified polyimide insulating paint:

[0051] (1) 0.008 mol of POSS-structured diamine A, 0.004 mol of POSS-structured diamine B and 0.088 mol of 4,4'-diamino diphenyl ether were added into 150 g of N,N'-dimethylacetamide, stirred at 50°C for 15 min, then 0.045 mol of pyromellitic dianhydride was added, stirred at 40°C for 30 min, then 0.045 mol of pyromellitic dianhydride was added again, stirred at 70°C for 3 h, then the temperature was increased to 90°C, and stirred for 30 min to obtain a polyamic acid resin;

[0052] (2) 5 g of MoS2 nanoparticles with a particle size of 50 nm were added into 100 g of the polyamic acid resin, stirred at room temperature for 30-45 min to obtain a corona-resistant and high-wear-resistant modified polyimide insulating paint.

[0053] Example 6: Preparation of a corona-resistant and high-wear-resistant modified polyimide insulating paint:

[0054] (1) 0.006 mol of POSS-structured diamine A, 0.006 mol of POSS-structured diamine B and 0.088 mol of 4,4'-diamino diphenyl ether were added into 150 g of N,N'-dimethylacetamide, stirred at 50°C for 15 min, then 0.045 mol of pyromellitic dianhydride was added, stirred at 40°C for 30 min, then 0.045 mol of pyromellitic dianhydride was added again, stirred at 70°C for 3 h, then the temperature was increased to 90°C, and stirred for 30 min to obtain a polyamic acid resin;

[0055] (2) 5 g of MoS2 nanoparticles with a particle size of 50 nm were added into 100 g of the polyamic acid resin, stirred at room temperature for 30-45 min to obtain a corona-resistant and high-wear-resistant modified polyimide insulating paint.

[0056] Comparative Example 1:

[0057] The difference between Comparative Example 1 and Example 2 is that the POSS-structured diamine A is replaced by 4,4'-diamino diphenyl ether.

[0058] Comparative Example 2:

[0059] The difference between Comparative Example 2 and Example 2 is that the POSS-structured diamine A is replaced by N-phenylaminopropyl cage silsesquioxane.

[0060] Performance test:

[0061] Preparation of paint film: the copper wire was cleaned with alcohol, then placed in a drying oven and dried at 120°C for 2 h, cooled and taken out for use, then the insulating paint prepared in the examples and comparative examples was coated on the surface of the copper wire, and cured at 200°C for 3 h to obtain a paint film with a thickness of 100 μm.

[0062] Mechanical property test: measured by universal tensile testing machine, the tensile rate was 10 mm / min, and the test results were shown in Table 1.

[0063] Dielectric property test: dielectric property test was performed by a broadband dielectric impedance spectrometer, the test temperature was 25℃, the relative humidity was 30%, and the test results were shown in Table 1.

[0064] Breakdown test: the breakdown strength of the paint film was tested by a breakdown field strength tester, the voltage increasing rate was 1 kV / s, and the test results were shown in Table 1.

[0065] Wear resistance test: the friction and wear properties of the material were tested by a friction and wear tester, the friction load was 12 N, the wear time was 3600 s, the reciprocating friction was used, the frequency was 2 Hz, the wear rate was tested according to the formula W = ΔV / FL, wherein F was the normal load (N), L was the total sliding length (mm), ΔV was the volume wear amount (mm 3 ), and the test results were shown in Table 1.

[0066] Adhesion test: the adhesion between the paint film and the substrate was tested by a universal tensile testing machine, the tensile rate was 0.3 mm / min, and the test results were shown in Table 1.

[0067] Table 1 Performance test results

[0068]

[0069] Data analysis: from Examples 1-6, it can be seen that the polyimide insulating paint prepared in the application has excellent mechanical properties and adhesion, and has high dielectric constant and breakdown strength, which helps to improve the corona resistance of the insulating paint, and most importantly, has high wear resistance and can maintain stability for a long time. This is mainly due to the easy agglomeration of nano-inorganic particles, which has poor dispersion effect in the solution, and the introduction of POSS structure can well solve the agglomeration defect of nano-inorganic particles

[0070] From Examples 2 and 4-6, it can be seen that the simultaneous presence of cage silsesquioxane in the main chain and the side chain helps to further improve the wear resistance, which is mainly due to the improvement of the rigidity of the main chain and the interlocking effect of the side chain, which synergistically improves the wear resistance, and also has excellent mechanical properties and corona resistance.

[0071] From Examples 2 and Comparative Examples 1-2, it can be seen that the diamine containing POSS structure in the application can significantly improve the performance of the polyimide, especially the adhesion and wear resistance, which is due to the active groups of the POSS structure which is beneficial to the compatibility of MoS2 and polyimide, and the synergistic effect of POSS structure and MoS2 can effectively improve the adhesion and wear resistance of the paint film.

[0072] Those skilled in the art should understand that the above discussion of any embodiment is merely exemplary in nature and is not intended to imply that the present application is limited to these examples; any of the above embodiments or technical features among different embodiments can be combined, and steps can be implemented in any order, under the idea of the present application, and there are many other changes of different aspects of the present application as described above, which are not provided in details for the sake of brevity.

[0073] The present application is intended to cover all such alternatives, modifications, and variations as fall within the broad scope of the appended claims. Accordingly, any one of the above- described embodiments or technical features among different embodiments can be combined, and steps can be implemented in any order, under the idea of the present application, and any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A corona-resistant, high abrasion-resistant modified polyimide insulating paint, characterized by, The polyamic acid resin is synthesized from dianhydride and diamine; the diamine includes POSS structure containing diamine and aromatic diamine; the molar ratio of the POSS structure containing diamine and the aromatic diamine is 0.1-0.2:1; The diamine containing POSS structure is a mixture of Formula I and Formula II at a molar ratio of 1:0.5-1; (I) (II); The dianhydride is selected from pyromellitic dianhydride; the aromatic diamine is selected from 4,4'-diamino diphenyl ether; The nano inorganic particles contain MoS2 nanoparticles with a size of 1-100 nm, and the content of the MoS2 nanoparticles is 0.1-30 wt% of the polyamic acid resin.

2. The corona resistant, high abrasion resistant modified polyimide insulating paint according to claim 1, characterized in that, The nano inorganic particles also contain one or more of the following: auxiliary modified silicon dioxide, auxiliary modified titanium dioxide, and auxiliary modified aluminum trioxide; the auxiliary is selected from one or more of the following: polymethyl methacrylate, polyvinyl alcohol, polycarbonate, and polyvinyl acetate.

3. The corona resistant, high abrasion resistant modified polyimide insulating paint of claim 1, wherein, The molar ratio of the dianhydride and the diamine is 0.8-1.1:

1.

4. The corona resistant, high abrasion resistant modified polyimide insulating paint of claim 1, wherein, The polyamic acid resin is synthesized in an organic solvent; the organic solvent is selected from one or more of the following: N-methyl pyrrolidone, N,N'-dimethylacetamide, N,N'-dimethylformamide, dimethyl sulfoxide, gamma-butyrolactone, propylene glycol methyl ether acetate, propylene glycol diacetate, ethylene glycol monomethyl ether acetate, and ethylene glycol monoethyl ether acetate.

5. A process for the preparation of a corona resistant, high abrasion resistant modified polyimide insulating varnish according to any one of claims 1 to 4, characterized in that, The method includes the following steps: (1) mixing and stirring the dianhydride and the diamine in an organic solvent to obtain a POSS modified polyamic acid resin; (2) adding nano inorganic particles to the POSS modified polyamic acid resin and fully stirring to obtain a corona resistant and high wear resistant modified polyimide insulating paint.

6. Use of the corona-resistant, high abrasion-resistant modified polyimide insulating paint according to any one of claims 1 to 4, characterized in that, The insulating paint is used to prepare an electromagnetic wire in an electric vehicle or a high-voltage driving motor; the use method of the insulating paint is to coat the insulating paint on the surface of a copper wire, cure at 100-500°C for 1-5h, and form an insulating layer containing a polyimide structure with a thickness of 10-500μm.

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