Environment-friendly polyimide insulating paint, preparation method and application thereof

Abstract

The application provides an environmentally friendly polyimide insulating paint and a preparation method and application thereof, and relates to the field of insulating paint; raw materials of the polyimide insulating paint are specific dianhydride and diamine, and a green biomass solvent is used simultaneously, so that the polyimide insulating paint has excellent performance, and can effectively improve the long-term exposure risk of an operator in a preparation process and meet the demand for environmental protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of insulating paint, in particular to an environment-friendly polyimide insulating paint and its preparation method and application. BACKGROUND

[0002] Polyimide (PI) is the preferred insulating material for preparing high-performance flat wire enameled wire, has the advantages of molecular structure, process scheduling, and high performance PI insulating paint with high solid content and high viscosity can improve the uniformity of R angle coating of flat wire.

[0003] Generally, PI insulating paint is prepared by reacting diamine and dianhydride in polar aprotic solvent, the most commonly used solvents include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N-methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO) and the like, for example: patent CN116162407A discloses a high-voltage resistant and corona resistant polyimide insulating paint material and its preparation method, the raw materials of the polyimide insulating paint material include resin and nano inorganic particles, wherein the resin contains polyimide and / or polyamide acid structure, the resin is prepared from dianhydride and diamine, the diamine includes silane and / or siloxane containing bisamino structure, and aromatic diamine, the mass ratio of the resin to the solid in the nano inorganic particles is 99:1-50:50. The solvent is selected from one or more of DMF, DMAc, NMP, gamma-hexalactone, toluene and xylene. The polyimide insulating paint material in the invention has excellent heat resistance, mechanical toughness, high-voltage resistance and corona resistance, and has the advantages of simple processing, excellent storage stability, high solid content and low viscosity.

[0004] For example, patent CN106336795A discloses an aromatic polyimide enameled wire paint and its preparation method, the raw materials thereof include component A and component B, the weight ratio of the component A to the component B is 1:10.5-17.5, the component A includes the following components: nano filler, silane coupling agent, organic solvent, the component B includes the following components: polyimide enameled wire paint, anti-settling agent, sodium silicate, wherein the organic solvent is a combination of one or more of DMF, DMAc, NMP, DMSO, toluene and xylene. The aromatic polyimide enameled wire paint provided by the invention can reach a thermal level of 260 or above, and can adapt to a working environment with higher temperature; other performance indicators also meet the standard requirements.

[0005] The proportion of solvents in the PI insulating paint product is more than 60%, but the solvents such as DMAc, DMF, NMP and DMSO are toxic to human health, and the waste liquid generated in the production process will further harm nature and the environment, so a large amount of protection and treatment resources must be invested in the process of processing and using the PI insulating paint containing these solvents to reduce and avoid harm to the human body and the environment. Therefore, it is necessary to develop a green and environmentally friendly polyimide insulating paint with excellent performance. SUMMARY

[0006] The present application provides an environmentally friendly polyimide insulating paint, its preparation method and application, which can effectively improve the long-term exposure risk of operating personnel in the preparation process of polyimide insulating paint, and meet the demand of environmental protection.

[0007] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0008] The present application provides a polyimide insulating paint, the raw materials of which include dianhydride, diamine and solvent.

[0009] The dianhydride includes one or more of p-phenyl bis(trimellitate) diacid anhydride (TAHQ), bisphenol A diether dianhydride (BPDAD), pyromellitic dianhydride (PMDA), biphenyl tetracarboxylic dianhydride (BPDA), diphenyl ether tetracarboxylic dianhydride (ODPA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), bisphenol AF diester dianhydride, p- biphenylene-bis-trimellitate dianhydride and bisphenol S diester dianhydride.

[0010] The diamine includes one or more of 4,4'-diamino diphenyl ether (ODA), 2,2'-bis[4-(4-aminophenoxyphenyl)]propane (BAPP), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,3-bis(4-aminophenoxy)benzene (134APB), 1,4-bis(4-aminophenoxy)benzene (144APB), 4,4'-diamino-2,2'-dimethylbiphenyl (M-Tolidine), 3,4'-diaminobenzanilide, bisphenol A diester diamine, bisphenol S diester diamine and bis(4-aminophenyl)terephthalate.

[0011] Preferably, the dianhydride and / or diamine contains an ester bond, the proportion of the dianhydride containing an ester bond in the total dianhydride content is ≥10 mol%, and / or the proportion of the diamine containing an ester bond in the total diamine content is ≥10 mol%. Here, ≥10 mol% means that there are more than 10 mol of dianhydride containing an ester bond in 100 mol of all dianhydride, and / or more than 10 mol of diamine containing an ester bond in 100 mol of all diamine.

[0012] Further, the dianhydride containing an ester bond includes one or more of p-phenyl bis(trimellitate) dianhydride, bisphenol AF diester dianhydride, p-biphenylene-bisbenzotrimellitate dianhydride, and bisphenol S diester dianhydride, and the diamine containing an ester bond includes one or more of bisphenol A diester diamine, bisphenol S diester diamine, and bis(4-aminophenyl) terephthalate.

[0013] Further, the solvent includes one or more of γ-butyrolactone (GBL), γ-valerolactone (GVL), TamiSolve (NxG), isosorbide dimethyl ether (DMI), dihydrolevoglucosenone (CyreneTM), water, methanol, ethanol, and isobutanol. The above-mentioned solvents have the characteristics of low volatility, low flammability, low toxicity, biodegradability, and recyclability.

[0014] Further, the polyimide insulating paint further includes a filler, and the filler includes one or more of aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon nitride, silicon carbide, boron carbide, graphite, silicon dioxide, and titanium dioxide.

[0015] Further, the polyimide insulating paint further includes an auxiliary agent, and the auxiliary agent includes one or more of a flame retardant, a plasticizer, an antifoaming agent, a leveling agent, a coupling agent, and a diluent. The above-mentioned auxiliary agent is preferably a bio-based auxiliary agent or a green auxiliary agent with little harm to the environment.

[0016] Preferably, the auxiliary agent includes one or more of triphenylphosphine, polyamine phosphate, aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, terephthalate diphenyl, bis(2-carboxyethyl)methyl phosphine oxide, tricresyl phosphate, dibutyl sebacate, and triphenyl phosphate.

[0017] Further, the weight average molecular weight of the polyimide insulating paint is 30000-200000 g / mol, the solid content of the prepolymer of the polyimide insulating paint is 5-50 wt%, and the solvent content is 50-95 wt%. The aforementioned solid content of the prepolymer is specifically the mass of the polyimide prepolymer / mass of the polyimide insulating paint.

[0018] Further, the molar ratio of the diamine and dianhydride is 1:(0.95-1.05). Preferably, it is 1:1.

[0019] Further, the polyimide insulating paint comprises 5-50 wt% of the polyimide prepolymer and the rest of the solvent.

[0020] Preferably, the polyimide insulating paint comprises 5-50 wt% of the polyimide prepolymer, 40-80 wt% of the solvent, 1-10 wt% of the filler and 1-10 wt% of the auxiliary.

[0021] Preferably, the polyimide insulating paint comprises 10-25 wt% of the polyimide prepolymer, 5-10 wt% of the auxiliary and the rest of the solvent.

[0022] Further preferably, the polyimide insulating paint comprises 10-25 wt% of the polyimide prepolymer, 1-5 wt% of the filler, 5-10 wt% of the auxiliary and the rest of the solvent.

[0023] Further, the application further provides a preparation method of the polyimide insulating paint, comprising the following steps: polycondensation of the diamine and the dianhydride in the solvent to obtain the polyimide prepolymer, and heating and imidization to obtain the polyimide insulating paint.

[0024] In some specific embodiments, the preparation method of the polyimide insulating paint comprises the following steps: polycondensation of the diamine and the dianhydride in the solvent to obtain the polyimide prepolymer, heating and stirring, and continuously adding the filler and the auxiliary to obtain the polyimide insulating paint.

[0025] Further, the heating temperature is 45℃, and the stirring time is 12h.

[0026] Further, the application provides the polyimide insulating paint or the polyimide insulating paint prepared by the preparation method.

[0027] The application achieves the following technical effects:

[0028] The solvent used in the application has the characteristics of low volatility, low flammability, low toxicity, biodegradability and recyclability, and is used in combination with specific components of dianhydride and diamine, which can effectively improve the long-term exposure risk of the operator during the preparation process of the polyimide insulating paint, meet the environmental protection demand, and still has excellent performance under high temperature and high humidity conditions. DETAILED DESCRIPTION

[0029] Following are specific examples illustrating the embodiments of the present application, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the specification. The present application can also be implemented or applied by other different specific embodiments, and various modifications or changes can be made to the details in the specification based on different views and applications without departing from the spirit of the present application.

[0030] Before further describing the specific embodiments of the present application, it should be understood that the scope of protection of the present application is not limited to the following specific embodiments; it should also be understood that the terms used in the embodiments of the present application are for the purpose of describing the specific embodiments, and are not intended to limit the scope of protection of the present application.

[0031] When the embodiments give numerical ranges, it should be understood that, unless otherwise stated by the present application, both endpoints of each numerical range and any number between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0032] It is worth noting that TamiSolve (NxG) used in the present application is purchased from Eastman, isosorbide dimethyl ether (DMI) is purchased from Wuhan Xinxinjiali Biological Technology Co., Ltd., dihydrolevoglucosenone (CyreneTM) is purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd., and the rest of the raw materials are ordinary commercially available products, so their sources are not specifically limited.

[0033] Examples 1-8, Comparative Examples 1-4

[0034] Example 1: A method for preparing an environmentally friendly polyimide insulating paint, comprising the following steps:

[0035] In a 500ml three-necked flask with nitrogen, stirring paddle and condenser, 256.12g NxG solvent and 0.1mol p-PDA diamine monomer were added, and after fully stirring and dissolving at 45℃, 16.01g nano-alumina was added, followed by 0.07mol bisphenol AF diester dianhydride monomer and 0.03mol BPDA dianhydride, and after stirring for 12 hours, the viscosity was stable, then 3% triphenyl phosphate and 2% aminopropyl triethoxysilane were added, and the insulating paint of Example 1 was prepared. According to the synthesis method of Example 1, the insulating paints of Examples 2-8 and Comparative Examples 1-4 were prepared for analysis and comparison.

[0036] The performance of the above prepared insulating material was evaluated, and the specific method is shown as follows:

[0037] (1) Insulating paint viscosity

[0038] A small amount of insulating paint material was used to cover the test rotor, and a Bruker DVPlus cone and plate viscometer was used to test three times and take the average.

[0039] (2) GPC test

[0040] Waters-1515-2414 gel chromatograph, test speed 1 ml / min, mobile phase DMF, column temperature 35°C, detector 40°C.

[0041] (3) Insulated wire manufacturing method

[0042] The insulating paint of each example in the present application was coated on a copper wire with a circular cross-sectional area (d = 1 mm) three times, and baked at a high temperature of 350°C for 30 minutes and at 450°C for 20 minutes to obtain an insulating layer with a thickness of 15 μm.

[0043] The insulating paint of each example in the present application was coated on a copper wire with a flat cross-sectional area (a = 2.5 mm, b = 4 mm, R corner radius 0.8 mm) ten times, and baked at a high temperature of 350°C for 30 minutes and at 450°C for 20 minutes to obtain an insulating layer with a thickness of 80 μm. Used for adhesion after 85 RH%, 85°C storage for 30 days.

[0044] (4) PI film preparation

[0045] On the glass, the polyimide prepolymer resin was uniformly scraped to a certain thickness, pre-baked at 80°C for 1 hour, then heated to 400°C, heating time 2 hours, imidization was completed, after cooling, the polyimide film with a uniform thickness of 20 μm was obtained by peeling off from the glass substrate for dielectric constant test, elongation, insulation strength, flame retardant test after 85 RH%, 85°C storage for 30 days.

[0046] (5) Adhesion

[0047] According to GBT7095.6-2008, the circular and flat samples were respectively stretched to test the elongation. The circular and flat samples were respectively stretched to test 20%, and the distance of losing the adhesion of the insulating layer was less than 1b, which was qualified for adhesion. Universal electronic testing machine: Shimadzu XG-Plus.

[0048] (6) Dielectric constant

[0049] Agilent network analyzer E5063A-2H5, frequency 10 GHz.

[0050] (7) Vertical burning test

[0051] The polyimide film was tested after 85 RH%, 85°C storage for 30 days, referring to GB T 2408-2021 Standard Test Methods for Determining the Burning Behavior of Plastics by Horizontal and Vertical Methods.

[0052] (8) Elongation test

[0053] Polyimide film 85 RH%, tested after 30 days storage at 85℃, Shimadzu AG-X plus tensile machine, extensometer TR View X, sample width 10 cm, gauge length 50 mm, test speed 100 mm / min.

[0054] (9) Breakdown strength test

[0055] The test was performed according to GB-T 13542.6-2006 Thin film for electrical insulation - Part 6: Polyimide film for electrical insulation.

[0056] The raw material composition and performance of the polyimide insulating varnish in Examples 1-8 and Comparative Examples 1-4 are shown in Tables 1-2.

[0057] Table 1 Composition of polyimide insulating varnish in Examples 1-8 and Comparative Examples 1-4

[0058]

[0059]

[0060] (Note: The percentages in the above table are all weight percentages. The solid content = the mass of the polyimide prepolymer / the mass of the polyimide insulating varnish, excluding the polyimide prepolymer, fillers and additives, the remaining is the solvent content. The molar ratio of the dianhydride and diamine in each example is 1:1.)

[0061] Table 2 Performance of polyimide insulating varnish in Examples 1-8 and Comparative Examples 1-4

[0062]

[0063] Finally, it should be noted that the above content is only used to illustrate the technical solutions of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A polyimide insulating varnish, characterized in that: Ingredients include: p-Biphenylene trimellitic acid dianhydride, pyromellitic anhydride, 4,4'-diaminodiphenyl ether and a solvent, wherein the molar ratio of p-biphenylene trimellitic acid dianhydride, pyromellitic anhydride and 4,4'-diaminodiphenyl ether is 30:70:100, and the solvent is dihydro-levulinone; or p-phenylenediamine (trimellitic acid ester) dianhydride, 4,4'-diaminodiphenyl ether, and a solvent, wherein the molar ratio of p-phenylenediamine (trimellitic acid ester) dianhydride to 4,4'-diaminodiphenyl ether is 100:100, and the solvent is dimethyl isosorbide; or 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, bisphenol A diester diamine, and a solvent, wherein the molar ratio of the 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, and bisphenol A diester diamine is 100:50:50, and the solvent is gamma-valerolactone and ethanol in a mass ratio of 80:20; or Pyromellitic anhydride, 1,3-bis(3-aminophenoxy)benzene, bis(4-aminophenyl)terephthalate and a solvent; the molar ratio of the pyromellitic anhydride, 1,3-bis(3-aminophenoxy)benzene and bis(4-aminophenyl)terephthalate is 100:90:10; and the solvent is gamma-butyrolactone and water in a mass ratio of 90:

10.

2. The polyimide insulating varnish according to claim 1, characterized in that: The raw materials of the polyimide insulating varnish further include fillers, and the fillers include one or more of aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon nitride, silicon carbide, boron carbide, graphite, silicon dioxide and titanium dioxide.

3. The polyimide insulating varnish according to claim 1, wherein: The raw materials of the polyimide insulating varnish further include auxiliary agents, which include one or more of a flame retardant, a plasticizer, a defoaming agent, a leveling agent, a coupling agent and a diluent.

4. The polyimide insulating varnish according to claim 3, characterized in that: The auxiliary agent includes one or more of triphenylphosphine, polyamine phosphate, aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, diphenyl terephthalate, bis(2-carboxyethyl)methylphosphine oxide, tricresyl phosphate, dibutyl sebacate and triphenyl phosphate.

5. The polyimide insulating varnish according to claim 1, characterized in that: Calculated by weight percentage, the invention comprises 5-50 wt% of a polyimide prepolymer, 40-80 wt% of a solvent, 1-10 wt% of a filler and 1-10 wt% of an auxiliary agent.

6. The method for preparing a polyimide insulating varnish according to any one of claims 1 to 5, wherein: The following steps are involved: In a solvent, diamine and dianhydride are polycondensed to obtain a polyimide prepolymer, which is then heated for imidization to obtain a polyimide insulating varnish.

7. Use of the polyimide insulating varnish according to any one of claims 1 to 5 or the polyimide insulating varnish prepared by the preparation method according to claim 6 in new energy vehicles.

Images