Preparation method and application of polyester lubricant for polyimide paint

Abstract

The invention belongs to the technical field of polyimide paint, and in particular to a preparation method and application of a polyester lubricant for polyimide paint. The preparation method of the polyester lubricant for polyimide paint specifically comprises the following steps: S1, adding adipic acid, 1,9-nonanediol, 1,5-naphthyridine-4,8-diol and 6-(hydroxymethyl)-1H-indole-4-ol into a container in sequence, heating the temperature to 140-150°C, and keeping the temperature constant for 0.5-1.5 hours; S2, heating the temperature to 220-230°C, and keeping the temperature constant for 0.5-1.5 hours; S3, adding n-butyl titanate, reacting until the acid value is qualified, cooling and packaging. The polyester lubricant for polyimide obtained by the preparation method of the present invention is evenly coated, not easy to fall off, has excellent self-lubrication, wear resistance, and has excellent high temperature thermal shock resistance, with a high temperature thermal shock temperature of 260°C.

Description

Technical Field

[0001] The invention relates to a preparation method and application of a polyester lubricant for polyimide paint, belonging to the technical field of polyimide paint. Background Art

[0002] Polyimide varnish, due to its excellent electrical insulation, heat resistance, and chemical corrosion resistance, is now widely used in the electronics, medical devices, and aerospace industries. Polyimide varnish is a polyimide varnish solution consisting of polyimide or a polyimide precursor dissolved in an organic solvent. This solution is applied to a substrate and, through heat treatment, forms a polyimide coating. Polyimide varnish requires the use of a lubricant during use to enhance its lubricity and wear resistance. Lubricants used in polyimide varnish primarily include solid lubricants, waxes, and polyurethane lubricants.

[0003] Chinese invention patent publication number CN1197925C reports on a polyimide-based high-temperature and radiation-resistant lubricating coating. Using molybdenum disulfide as a lubricant, and adding modifiers such as lead phosphite and antimony trioxide, the resulting polyimide coating exhibits high-temperature resistance (up to 300°C-370°C), strong radiation resistance, and excellent lubricity. Chinese invention patent application publication number CN1772812A reports on a reinforced, toughened, and wear-resistant polyimide composite material. Using polytetrafluoroethylene, molybdenum disulfide, and graphite as solid lubricants, the resulting material exhibits low friction and wear resistance. Chinese invention patent application publication number CN112661948A reports a polyester polyol for producing high-heat-resistant polyurethane wire enamel and its preparation method. The method uses ethylene glycol, neopentyl glycol, 2-methyl-1,3-propanediol, butyl orthotitanate, and polyfunctional alcohols and acids such as adipic acid and phthalic anhydride. However, the resulting polyurethane enamel has a short 230°C heat shock resistance time. Chinese invention patent application publication number CN103725194A reports an H-grade, low-temperature, direct-weld polyurethane wire enamel and its preparation method. Using terephthalic acid, neopentyl glycol, 2-methyl-1,3-propanediol, adipic acid, phthalic anhydride, and additives such as nylon 12 and zinc borate, the product exhibits good adhesion, but its heat resistance only reaches 185°C.

[0004] Existing solid lubricants used in polyimide lacquers, such as graphite, molybdenum disulfide, and fluoride, suffer from uneven coating, rough surfaces that fail to meet application requirements, poor compatibility, and easy shedding. Polyester lubricants, on the other hand, lack ideal heat resistance and cannot be used in high-temperature environments for extended periods. They also have poor bonding with polyimide resins and offer poor resistance to high-temperature thermal shock. Summary of the Invention

[0005] The present invention aims to solve the technical problems that traditional polyester lubricant paints have low heat resistance and poor bonding strength with polyimide resins, and provides a preparation method and application of a polyester lubricant for polyimide paint.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: a method for preparing a polyester lubricant for polyimide paint, specifically comprising the following steps:

[0007] S1. Add adipic acid, 1,9-nonanediol, 1,5-naphthyridine-4,8-diol and 6-(hydroxymethyl)-1H-indole-4-ol to a container in sequence, raise the temperature to 140° C. to 150° C., and keep the temperature constant for 0.5 to 1.5 hours;

[0008] S2. Raise the temperature to 220°C to 230°C and keep the temperature constant for 0.5 to 1.5 hours;

[0009] S3. Add n-butyl titanate, react until the acid value meets the requirements, cool down and package.

[0010] On the basis of the above technical solution, the present invention can also make the following improvements:

[0011] Furthermore, the molar ratio of the 1,9-nonanediol, 1,5-naphthyridine-4,8-diol, and 6-(hydroxymethyl)-1H-indole-4-ol is 7-11:1-3:1-3.

[0012] Further, the amounts of raw materials used are as follows:

[0013] Adipic acid 5.50 mol to 7.00 mol;

[0014] 1,9-nonanediol 3.00 mol to 6.00 mol;

[0015] 1,5-naphthyridine-4,8-diol 0.50 mol to 2.00 mol;

[0016] 6-(Hydroxymethyl)-1H-indol-4-ol 0.50 mol to 2.00 mol;

[0017] n-Butyl Titanate 1.6x10 -4 mol~2.6x10 -4 mol.

[0018] Furthermore, step S1 is performed under nitrogen atmosphere protection.

[0019] Furthermore, in step S2, the heating rate is 40°C / hour.

[0020] Furthermore, in step S3, the reaction is carried out until the acid value is less than 0.50 mg KOH / g.

[0021] Furthermore, in step S1, the temperature is raised to 145° C. and the constant temperature time is 1 hour.

[0022] Furthermore, in step S2, the temperature is raised to 225° C. and the constant temperature time is 1 hour.

[0023] A polyimide paint comprises a polyester lubricant for polyimide paint prepared by the above-mentioned method for preparing the polyester lubricant for polyimide paint.

[0024] Furthermore, the polyimide paint comprises the following components by mass fraction:

[0025] Polyimide resin 40wt%~50wt%;

[0026] The polyester lubricant for the polyimide paint is 9wt% to 11wt%;

[0027] Diphenylmethane diisocyanate 13wt%~15wt%;

[0028] Trimethylolpropane 0.4wt%~ 0.6wt%;

[0029] Fumed silica 1wt%~2wt%;

[0030] Nano-alumina 1wt%~2wt%;

[0031] The balance is solvent.

[0032] Furthermore, the solvent is N-methylpyrrolidone and / or N,N-dimethylacetamide.

[0033] Traditional polyimide paint uses polyester lubricants prepared from diols such as ethylene glycol, neopentyl glycol, and 2-methyl-1,3-propylene glycol. It has a low heat resistance level and does not have strong bonding with polyimide resin.

[0034] The beneficial effects of the present invention are as follows: the small molecule alcohols used in the present invention are 1,9-nonanediol, 1,5-naphthyridine-4,8-diol and 6-(hydroxymethyl)-1H-indole-4-ol; the long-chain 1,9-nonanediol with an odd number of carbon atoms has poor crystallinity; therefore, the polyester lubricant prepared using the long-chain 1,9-nonanediol has low viscosity, thereby having good high-temperature oxidation resistance and wear resistance; the introduction of the benzene ring structures of 1,5-naphthyridine-4,8-diol and 6-(hydroxymethyl)-1H-indole-4-ol enables the polyester lubricant to have a strong π-π stacking effect with the aromatic polyimide, and the NH bond structure in 6-(hydroxymethyl)-1H-indole-4-ol has a strong hydrogen bond interaction with the imide; in addition, the introduction of the biheteroaromatic ring of 1,5-naphthyridine-4,8-diol enables the polyester product to have excellent heat resistance. The polyester lubricant for polyimide prepared by the preparation method of the present invention is evenly coated and not easy to fall off, has excellent self-lubrication and wear resistance, and has excellent high-temperature thermal shock resistance, and the high-temperature thermal shock resistance temperature reaches 260°C. DETAILED DESCRIPTION

[0035] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0036] Example 1

[0037] The preparation method of a polyester lubricant for polyimide paint specifically comprises the following steps:

[0038] Under nitrogen atmosphere, 6.06 mol of adipic acid, 4.981 mol of 1,9-nonanediol, 0.99 mol of 1,5-naphthyridine-4,8-diol and 0.99 mol of 6-(hydroxymethyl)-1H-indole-4-ol were added to a 2000 mL reaction bottle in sequence, and the temperature was raised to 145 ° C and kept at this temperature for 1 hour. Then, the temperature was raised to 225 ° C at a rate of 20 ° C in 30 minutes and kept at this temperature for 1 hour. 2.0x10 -4 mol n-butyl titanate.

[0039] React until the acid value is <0.50mg KOH / g and the hydroxyl value is 56 mg KOH / g~59 mg KOH / g. After the hydroxyl value is qualified, cool down and package.

[0040] The raw material dosages and experimental results of Examples 1 to 6 are shown in Table 1 below. The preparation processes of Examples 2 to 6 are the same as those of Example 1 and will not be described in detail.

[0041] Table 1 Material ratios and experimental results of Examples 1 to 6

[0042]

[0043] Examples 7 to 12

[0044] The polyester lubricant AF for polyimide paint prepared in Examples 1 to 6 (10% by mass) was reacted with diphenylmethane diisocyanate (14% by mass) and trimethylolpropane (0.5% by mass). After the NCO content was qualified (i.e., the NCO% was 1.9% to 2.1%), lubricant 2 was obtained. Lubricant 2 was uniformly mixed with a polyimide resin, a filler, and an organic solvent to obtain a polyimide paint, which was then wrapped and coated onto a copper flat wire for physical property testing.

[0045] The polyimide paint comprises the following components in the following mass ratios:

[0046] Polyimide resin 40 wt% to 50 wt%;

[0047] Lubricant 2 22.4wt%~26.6wt%wt%

[0048] Fumed silica 1 wt% to 2 wt%;

[0049] Nano-alumina 1 wt% to 2 wt%;

[0050] The remaining components are the solvents N-methylpyrrolidone (NMP) and N,N-dimethylacetamide (DMAc).

[0051] The material ratios of Examples 7 to 12 and Comparative Examples 1 to 6 are shown in Table 2.

[0052] The test results of Examples 7 to 12 and Comparative Examples 1 to 6 are shown in Table 3.

[0053] Performance testing is carried out according to the following test standards:

[0054] Paint film thickness test standard GB / T 6109-2008;

[0055] Temperature resistance test standard GB / T 6109-2008;

[0056] Elongation test standard GB / T 6109-2008;

[0057] Adhesion test standard GB / T 6109-2008.

[0058] The lubricants used in Examples 7-12 were lubricant 2, obtained by reacting the polyol lubricants A-F (10% by mass) prepared in Examples 1-6 with diphenylmethane diisocyanate (14% by mass) and trimethylolpropane (0.5% by mass). The lubricants used in Comparative Examples 1-6 were combinations of one or more solid, wax, or other polyester lubricants in the same mass ratios. Polyester lubricant 1 used in the comparative examples was a polyol series consisting of neopentyl glycol and 2-methyl-1,3-propanediol, each with a molecular weight of 2000, in a molar ratio of adipic acid: terephthalic acid: phthalic anhydride: neopentyl glycol: 2-methyl-1,3-propanediol of 11:2:9:8:16. Polyester lubricant 2 is a polyol of neopentyl glycol and ethylene glycol series with a molecular weight of 2000, and its ratio composition is adipic acid: trimellitic anhydride: phthalic anhydride: neopentyl glycol: ethylene glycol with a molar ratio of 1:10:6.5:5.6:14.

[0059] Table 2 Material ratios of Examples 7 to 12 and Comparative Examples 1 to 6

[0060]

[0061] Table 3 Test results of Examples 7 to 12 and Comparative Examples 1 to 6

[0062]

[0063] The experimental data of Examples 7 to 12 and Comparative Examples 1 to 6 show that the present invention creatively introduces 1,9-nonanediol, 1,5-naphthyridine-4,8-diol, and 6-(hydroxymethyl)-1H-indole-4-ol into the polyester polyol synthesis process, with the molar ratio of the three preferably being 7 to 11:1 to 3:1 to 3. The polyester lubricant for polyimide prepared by the present invention has excellent load-bearing, lubrication, and wear resistance, is evenly coated and does not easily fall off, which is superior to ordinary inorganic solid lubricants, and can be used in a high-temperature environment of 260°C for a long time without significant changes in product properties.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A polyimide paint, characterized in that: Calculated by mass fraction, it includes the following components: Polyimide resin 40wt%~50wt%; Polyester lubricant for polyimide paint 9%~11wt%; Diphenylmethane diisocyanate 13wt%~15wt%; Trimethylolpropane 0.4wt%~0.6wt%; Fumed silica 1wt%~2wt%; Nano-alumina 1wt%~2wt%; The balance is solvent; The preparation method of the polyester lubricant for polyimide paint specifically comprises the following steps: S1. Add adipic acid, 1,9-nonanediol, 1,5-naphthyridine-4,8-diol and 6-(hydroxymethyl)-1H-indole-4-ol to a container in sequence, raise the temperature to 140° C. to 150° C., and keep the temperature constant for 0.5 to 1.5 hours; S2. Raise the temperature to 220°C to 230°C and keep the temperature constant for 0.5 to 1.5 hours; S3. Add n-butyl titanate, react until the acid value meets the requirements, cool down and package.

2. The polyimide paint according to claim 1, characterized in that The molar ratio of the 1,9-nonanediol, 1,5-naphthyridine-4,8-diol and 6-(hydroxymethyl)-1H-indole-4-ol is 7-11:1-3:1-3.

3. The polyimide paint according to claim 2, characterized in that The raw material dosages used in the preparation method of polyester lubricant for polyimide paint are as follows: Adipic acid 5.50 mol to 7.00 mol; 1,9-nonanediol 3.00 mol to 6.00 mol; 1,5-naphthyridine-4,8-diol 0.50 mol to 2.00 mol; 6-(Hydroxymethyl)-1H-indol-4-ol 0.50 mol to 2.00 mol; n-Butyl Titanate 1.6x10 -4 mol~2.6x10 -4 mol.

4. The polyimide paint according to claim 3, characterized in that Step S1 is performed under nitrogen atmosphere protection.

5. The polyimide paint according to claim 3, characterized in that In step S2, the heating rate is 40°C / hour.

6. The polyimide paint according to claim 3, characterized in that: In step S3, the reaction is carried out until the acid value is less than 0.50 mgKOH / g.

7. The polyimide paint according to claim 4, characterized in that: In step S1, the temperature is raised to 145° C. and the temperature is maintained for 1 hour.

8. The polyimide paint according to claim 5 or 7, characterized in that: In step S2, the temperature is raised to 225° C. and the temperature is maintained for 1 hour.

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