Preparation method and application of polyester lubricant for polyimide paint

Abstract

The invention belongs to the technical field of polyimide paint, and particularly relates 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 that S1, adipic acid, 1, 9-nonanediol, 1, 5-naphthyridine-4, 8-diol and 6-(hydroxymethyl)-1H-indole-4-ol are sequentially added into a container, stirring is conducted for 1-3 h, and then the mixture is cooled to room temperature; raising the temperature to 140 DEG C to 150 DEG C, and keeping the constant temperature for 0.5 hour to 1.5 hours; s2, the temperature is raised to 220 DEG C to 230 DEG C, and the constant temperature is kept for 0.5 hour to 1.5 hours; s3, adding tetrabutyl titanate, reacting until the acid value is qualified, cooling and packaging. The polyester lubricant for polyimide prepared by the preparation method disclosed by the invention is uniform in coating, not easy to fall off, excellent in self-lubrication and wear resistance, and excellent in high-temperature thermal shock resistance, and the high-temperature thermal shock resistance temperature reaches 260 DEG C.

Description

Technical Field

[0001] The present 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] Due to its excellent electrical insulation, heat resistance, and chemical corrosion resistance, polyimide varnish has now been widely used in the fields of electronics and electrical appliances, medical devices, and aerospace. Polyimide varnish is a polyimide varnish solution obtained by dissolving a polyimide or a polyimide precursor in an organic solvent. When this solution is applied to a substrate and heat-treated, a polyimide coating film can be formed on the substrate. Lubricants are required during the use of polyimide paint to increase its lubricating performance and wear resistance. The lubricants used for polyimide paint mainly include solid lubricants, waxes, and polyurethane lubricants.

[0003] The Chinese invention patent with the publication number CN1197925C reported a polyimide-based high-temperature and radiation-resistant lubricating coating, which uses molybdenum disulfide as a lubricant and adds modifiers such as lead phosphite and antimony trioxide to prepare a polyimide coating with excellent high-temperature resistance (temperature resistance up to 300°C - 370°C), strong radiation resistance, and good lubricating performance. The Chinese invention patent application with the publication number CN1772812A reported a reinforced, toughened, and wear-resistant polyimide composite material, which uses polytetrafluoroethylene, molybdenum disulfide, and graphite as solid lubricants, and the prepared material has characteristics such as low friction and wear resistance. The Chinese invention patent application with the publication number CN112661948A reported a polyester polyol for producing high heat-resistant grade polyurethane enameled wire paint and its preparation method, which uses polyhydric alcohols and acids such as ethylene glycol, neopentyl glycol, 2-methyl-1,3-propanediol, tetrabutyl titanate, adipic acid, and phthalic anhydride for reaction, but the polyurethane paint prepared has a short heat shock time resistance at 230°C. The Chinese invention patent application with the publication number CN103725194A reported an H-grade low-temperature direct-soldering polyurethane enameled wire paint 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 has good adhesion performance, but its heat resistance grade only reaches 185°C.

[0004] Existing solid lubricants such as graphite, molybdenum disulfide, and fluorides used in polyimide paint have problems in use, such as uneven coating, rough surface that cannot meet the use requirements, poor compatibility, and easy shedding. Moreover, the heat resistance of polyester lubricants is not ideal enough, they cannot be used for a long time in high-temperature environments, have poor binding force with polyimide resin, and poor high-temperature heat shock resistance. Summary of the Invention

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

[0006] The technical solution of the present invention to solve the above technical problems is as follows: A preparation method of a polyester lubricant for polyimide paints specifically includes the following steps: S1. Add adipic acid, 1,9-nonanediol, 1,5-naphthyridine-4,8-diol, and 6-(hydroxymethyl)-1H-indol-4-ol into a container in sequence, heat up to 140°C to 150°C, and keep the temperature constant for 0.5 hour to 1.5 hours; S2. Heat up to 220°C to 230°C, and keep the temperature constant for 0.5 hour to 1.5 hours; S3. Add tetrabutyl titanate, react until the acid value is qualified, and then cool down and package.

[0007] On the basis of the above technical solution, the present invention can also make the following improvements: Further, the molar ratio of 1,9-nonanediol, 1,5-naphthyridine-4,8-diol, and 6-(hydroxymethyl)-1H-indol-4-ol is 7 to 11:1 to 3:1 to 3.

[0008] Further, the specific amounts of raw materials used 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; Tetrabutyl titanate: 1.6x10 -4 mol to 2.6x10 -4 mol.

[0009] Further, step S1 is carried out under the protection of a nitrogen atmosphere.

[0010] Further, in step S2, the heating rate is 40°C / hour.

[0011] Further, in step S3, the reaction is carried out until the acid value < 0.50 mg KOH / g.

[0012] Further, in step S1, the temperature is raised to 145°C, and the constant temperature time is 1 hour.

[0013] Further, in step S2, the temperature is raised to 225°C, and the constant temperature time is 1 hour.

[0014] A polyimide paint, the components of which include the polyester lubricant for polyimide paint prepared by the preparation method of the polyester lubricant for polyimide paint described above.

[0015] Furthermore, this polyimide paint, by mass fraction, includes the following components: Polyimide resin 40wt% - 50wt%; The polyester lubricant for polyimide paint described above 9wt% - 11wt%; Diphenylmethane diisocyanate 13wt% - 15wt%; Trimethylolpropane 0.4wt% - 0.6wt%; Fumed silica 1wt% - 2wt%; Nanometer alumina 1wt% - 2wt%; The balance is solvent.

[0016] Furthermore, the solvent is N-methylpyrrolidone and / or N,N-dimethylacetamide.

[0017] Traditional polyimide paints use polyester lubricants prepared from diols such as ethylene glycol, neopentyl glycol, and 2-methyl-1,3-propanediol, which have a relatively low heat resistance grade and do not have a strong binding force with polyimide resin.

[0018] 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 therefrom has a relatively low viscosity, so that it has 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 interaction with aromatic polyimide, and the N-H bond structure in 6-(hydroxymethyl)-1H-indole-4-ol has a strong hydrogen bond interaction with the imide. In addition, the introduction of the double heteroaromatic ring of 1,5-naphthyridine-4,8-diol makes the polyester product 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-lubricating and wear-resistant properties, and has excellent high-temperature thermal shock resistance, and the high-temperature thermal shock temperature reaches 260°C. Specific embodiments

[0019] The principles and features of the present invention are described below in conjunction with examples. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0020] Example 1 The preparation method of the polyester lubricant for polyimide paint specifically includes the following steps: Under the protection of 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 successively added to a 2000 mL reaction flask. The temperature was raised to 145 °C and kept constant for 1 hour. Then, at a heating rate of 20 °C every 30 minutes, the temperature was raised to 225 °C and kept constant for 1 hour, and 2.0x10 -4 mol of tetrabutyl titanate was added.

[0021] React until the acid value is <0.50 mg KOH / g and the hydroxyl value is 56 mg KOH / g to 59 mg KOH / g. After the hydroxyl value is qualified, cool down and package.

[0022] The raw material dosages and experimental results of Examples 1 to 6 are shown in Table 1 below. The preparation processes of Examples 2 - 6 are the same as that of Example 1 and will not be elaborated here.

[0023] Table 1 Material ratios and experimental results of Examples 1 to 6

[0024] Examples 7 - 12 The polyester lubricants A - F for polyimide paint (mass ratio 10%) prepared in Examples 1 to 6 above were reacted with diphenylmethane diisocyanate (mass ratio 14%) and trimethylolpropane (mass ratio 0.5%). After the NCO was qualified (i.e., NCO% was 1.9% - 2.1%), lubricant two was obtained. Lubricant two was mixed evenly with polyimide resin, filler, organic solvent, etc. to obtain polyimide paint, which was wound and coated on copper flat wires for physical property testing.

[0025] The polyimide paint comprises the following components in the following mass ratios: Polyimide resin 40 wt% - 50 wt%; Lubricant two 22.4 wt% - 26.6 wt%wt%; Fumed silica 1 wt% - 2 wt%; Nanometer alumina 1 wt% - 2 wt%; The remaining components are the solvents N-methylpyrrolidone (NMP) and N,N-dimethylacetamide (DMAc).

[0026] The material ratios of Examples 7 - 12 and Comparative Examples 1 - 6 are shown in Table 2.

[0027] The test results of Examples 7 - 12 and Comparative Examples 1 - 6 are shown in Table 3.

[0028] Performance testing was carried out according to the following test standards: Film thickness test standard: GB / T 6109-2008; Temperature resistance grade test standard: GB / T 6109-2008; Elongation rate test standard: GB / T 6109-2008; Adhesion test standard: GB / T 6109-2008.

[0029] Among them, the lubricants used in Examples 7 to 12 are successively Lubricant Two obtained by reacting corresponding polyol lubricants A to F (mass ratio 10%) prepared in Examples 1 to 6 with diphenylmethane diisocyanate (mass ratio 14%) and trimethylolpropane (mass ratio 0.5%); the lubricants used in Comparative Examples 1 to 6 are one or a combination of more of the same mass ratio of solid, wax or other polyester lubricants. Among them, Polyester Lubricant 1 used in the comparative example is neopentyl glycol and 2-methyl-1,3-propanediol series polyols with a molecular weight of 2000, and its mixing ratio composition is adipic acid: terephthalic acid: phthalic anhydride: neopentyl glycol: 2-methyl-1,3-propanediol molar ratio = 11:2:9:8:16. Polyester Lubricant 2 is neopentyl glycol and ethylene glycol series polyols with a molecular weight of 2000, and its mixing ratio composition is adipic acid: trimellitic anhydride: phthalic anhydride: neopentyl glycol: ethylene glycol molar ratio = 1:10:6.5:5.6:14.

[0030] Table 2 Material Mixing Ratios of Examples 7 to 12 and Comparative Examples 1 to 6

[0031] Table 3 Test Results of Examples 7 to 12 and Comparative Examples 1 to 6

[0032] It can be seen from the experimental data of Examples 7 to 12 and Comparative Examples 1 to 6 that in the process of synthesizing polyester polyol of the present invention, 1,9-nonanediol, 1,5-naphthyridine-4,8-diol, and 6-(hydroxymethyl)-1H-indol-4-ol are creatively introduced, and the molar ratio of the three is preferably 7 to 11:1 to 3:1 to 3. The polyester lubricant for polyimide prepared by the present invention has excellent anti-load bearing, lubrication and wear resistance, is evenly coated and not easy to fall off, is higher than ordinary inorganic solid lubricants, and can be used in a high temperature environment of 260°C for a long time without obvious change in product physical properties.

[0033] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a polyester lubricant for polyimide paint, characterized in that: The specific steps include: S1. Add adipic acid, 1,9-nonanediol, 1,5-naphthyridine-4,8-diol and 6-(hydroxymethyl)-1H-indol-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℃~230℃, and keep the temperature constant for 0.5 hour~1.5 hours; S3. Add n-butyl titanate, react until the acid value reaches a qualified value, cool down and package.

2. The method for preparing a polyester lubricant for 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-indol-4-ol is 7-11:1-3:1-3.

3. The method for preparing a polyester lubricant for polyimide paint according to claim 2, characterized in that: The specific amounts of raw materials used are as follows: Adipic acid 5.50 mol~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; Butyl Titanate 1.6x10 -4 mol~2.6x10 -4 mol.

4. The method for preparing a polyester lubricant for polyimide paint according to claim 3, characterized in that: Step S1 is performed under the protection of a nitrogen atmosphere.

5. The method for preparing a polyester lubricant for polyimide paint according to claim 3, characterized in that: In step S2, the heating rate is 40°C / hour.

6. The method for preparing a polyester lubricant for polyimide paint according to claim 3, characterized in that: In step S3, the reaction is performed until the acid value is less than 0.50 mg KOH / g.

7. The method for preparing a polyester lubricant for polyimide paint according to claim 4, characterized in that: In step S1, the temperature is raised to 145°C and the constant temperature time is 1 hour.

8. The method for preparing a polyester lubricant for polyimide paint according to claim 5 or 7, characterized in that: In step S2, the temperature is raised to 225°C and the constant temperature time is 1 hour.

9. A polyimide paint, characterized in that: The component comprises the polyester lubricant for polyimide paint prepared by the preparation method of the polyester lubricant for polyimide paint according to any one of claims 1 to 8.

10. The polyimide paint according to claim 9, characterized in that: In terms of mass fraction, it includes the following components: Polyimide resin 40wt%~50wt%; The polyester lubricant for the polyimide paint is 9% to 11wt%; Diphenylmethane diisocyanate 13wt%~15wt%; Trimethylolpropane 0.4wt%~0.6wt%; Fumed silica 1wt%~2wt%; Nano-alumina 1wt%~2wt%; The balance is solvent.

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