High-heat-dissipation lubricating coating material for coating aluminum sheet and preparation method of high-heat-dissipation lubricating coating material

Abstract

The invention belongs to the technical field of functional coatings, and particularly relates to a high-heat-dissipation lubricating coating material for coating an aluminum sheet and a preparation method of the high-heat-dissipation lubricating coating material. The coating material comprises a polyimide precursor, a filler, a solid lubricant and an organic solvent. The core is that a novel polyimide precursor is prepared through a specific synthesis process to serve as film-forming resin, and a rigid structural unit containing a triazole ring is introduced into a molecular chain of the resin. The triazole ring and the imide bond have a synergistic effect, and an effective phonon transmission channel is constructed by enhancing intermolecular hydrogen bonds and a pi-pi conjugation effect, so that the thermal conductivity of the coating is remarkably improved. Meanwhile, the molecular structure endows the coating with the characteristic of easy interlayer slippage, and the added molybdenum disulfide solid lubricant is combined to jointly realize excellent lubricating performance. By regulating and controlling the ratio of the rigid triazole ring to the flexible chain segment, the heat conduction, lubricating property, film-forming property and adhesive force of the coating are successfully balanced. The coating is particularly suitable for an aluminum-coated cover plate for PCB drilling, can effectively solve the problems of overheating and abrasion of a drill point, adhesion of drilling cuttings and the like, and improves the drilling quality and efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional coating, and particularly relates to a high-heat-dissipation and lubricating coating material for coated aluminum sheet and a preparation method thereof. BACKGROUND

[0002] Printed circuit board (PCB) is a key component in electronic equipment, and the drilling process in its manufacturing process is crucial to the precision and reliability of the final product. The hole wall quality and hole position accuracy are the core indicators to measure the drilling quality, which are complexly affected by various factors such as substrate material, drill needle and drilling process conditions. In order to protect the board and improve the drilling quality, the industry generally uses cover plate materials, among which the coated aluminum sheet has better effect than ordinary aluminum sheet due to the synergistic effect of its surface coating and aluminum matrix.

[0003] However, the existing coated aluminum sheet technology has obvious defects. The traditional adhesive resin coating has insufficient performance, and the currently widely used adhesive resin coating has poor heat dissipation and lubrication. This leads to the inability to effectively dissipate the high heat generated by the drill needle during drilling, and also cannot reduce the friction between the drill needle and the workpiece, thereby causing the drill needle to overheat and wear out, which ultimately seriously affects the drilling quality and hole position accuracy. This can cause serious adhesion of drill chips to the drill needle, aluminum sheet and PCB substrate, causing problems such as wire entanglement, hole plugging, residual drill chips and dust accumulation. These defects not only cause processing abnormalities such as drill needle breakage and hole position deviation, but also seriously restrict the further improvement of drilling efficiency and quality. Therefore, it is urgent to develop a high-heat-dissipation and lubricating coating for coated aluminum sheet to overcome the above problems. SUMMARY

[0004] The present application provides a high-heat-dissipation and lubricating coating material for coated aluminum sheet and a preparation method thereof. The obtained coating has high heat dissipation and lubrication, and also has good film forming property and adhesion, meeting the performance requirements of aluminum-coated cover plate in the PCB drilling application process.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0006] The present application provides a high-heat-dissipation and lubricating coating material for coated aluminum sheet, which comprises the following components: polyimide precursor, filler, solid lubricant and organic solvent.

[0007] Further, the high-heat-dissipation and lubricating coating material for coated aluminum sheet, by weight, the amount of each component is: 50-70 parts of polyimide precursor, 2-5 parts of filler, 3-5 parts of solid lubricant and 30-100 parts of organic solvent.

[0008] Further, the preparation process of the polyimide precursor comprises the following steps:

[0009] S1, under the protection of nitrogen, 4 mmol of 4,4'-diaminodiphenyl methane is added to a mixture of deionized water and concentrated hydrochloric acid, the reaction mixture is stirred at 3°C, 30 mL of sodium nitrite solution is added dropwise, stirring is continued for 1 h, 10 mL of sodium azide aqueous solution is added dropwise and the reaction is continued for 2 h, the system is allowed to stand for 8 h and then filtered to obtain 4,4'-diazidodiphenyl methane;

[0010] The specific reaction process of step S1 is as follows:

[0011]

[0012] S2, under the protection of nitrogen, 10 mmol of 4,4'-diazidodiphenyl methane prepared in step S1, 20 mmol of 3-aminophenylacetylene are dissolved in N,N-dimethylacetamide to form a mixture, and then appropriate amounts of CuSO4·5H2O, sodium ascorbate and triethylamine are added and stirred uniformly, then the temperature is raised to 60°C and the reaction is carried out for 6 hours, then a saturated solution of disodium ethylenediaminetetraacetate is added to form a precipitate, the precipitate is filtered, washed and vacuum dried to obtain intermediate 1;

[0013] The specific reaction process of step S2 is as follows:

[0014]

[0015] S3, under the protection of nitrogen, intermediate 1 prepared in step S2, 4,4'-diphenyl ether diamine are dissolved in N,N-dimethylacetamide to form a mixed solution, and phthalic anhydride is added in batches, stirred at 4°C for 12 h, then a certain amount of acetic anhydride and triethylamine are added for dehydration and cyclization, and the product is filtered, washed and vacuum dried to obtain the polyimide precursor;

[0016] The specific reaction process of step S3 is as follows:

[0017]

[0018] Further, the molar ratio of intermediate 1 to 4,4'-diphenyl ether diamine in step S3 is 1:1-3.

[0019] Further, the solid lubricant is molybdenum disulfide powder with a particle size of 0.5-1.0 um.

[0020] Further, the filler is one or more of calcium carbonate, calcined kaolin, mica powder and silicon dioxide.

[0021] Further, the organic solvent is N,N-dimethylacetamide.

[0022] The application further provides a preparation method of the coating material for the aluminum sheet, which comprises the following steps: uniformly coating the high-heat-dissipation lubricating coating material on the ground aluminum sheet substrate by using one of a brushing method, a spin coating method or a dip coating method, and then performing a defoaming procedure and a thermal imidization procedure to obtain the coating.

[0023] The defoaming procedure comprises the following steps in sequence: 80 DEG C for 12 h, 100 DEG C for 2 h and 120 DEG C for 12 h.

[0024] The thermal imidization procedure comprises the following steps in sequence: 150 DEG C for 1 h, 200 DEG C for 1 h, 250 DEG C for 1 h and 300 DEG C for 1 h under a nitrogen atmosphere.

[0025] Compared with the prior art, the application has the following advantages and technical effects:

[0026] 1. The polyimide precursor prepared by using the specific preparation process is used as a film-forming resin to be cured and formed into a film, the triazole ring structure is introduced into the polyimide resin, the triazole ring structure is a five-membered heterocyclic compound containing three nitrogen atoms, has similar properties to the imide bond in terms of strong dipole moment, hydrogen bond accepting ability and aromatic characteristics, can enhance the pi-pi conjugation effect, can also form a hydrogen bond with the carbonyl oxygen atom in the imide bond, the combination of the hydrogen bond and the pi-pi conjugation non-covalent interaction reduces phonon scattering, promotes heat transfer and long-range phonon transmission, and finally improves the heat conduction of the coating film. Meanwhile, the pi-pi conjugation stacking effect between the molecular chains can promote the relative slipping between the molecular chain segments when subjected to a shear force, and the effect cooperates with the interlayer slipping of the added molybdenum disulfide solid lubricant to jointly impart excellent macroscopic lubricating properties to the coating.

[0027] 2. The application also adjusts the amount of the raw material in the preparation process of the polyimide precursor, controls the introduction proportion of the rigid triazole ring, connects the rigid triazole ring with the flexible chain segment, ensures the best balance between the node rigidity and the spacer flexibility, and makes the coating film exhibit excellent heat conduction, lubricating properties, good film-forming properties and adhesion. DETAILED DESCRIPTION

[0028] In order to further illustrate the technical means and effects adopted by the application to achieve the predetermined application purposes, the specific embodiments, structures, features and effects according to the application are described in detail below.

[0029] The main products used in the following embodiments are as follows: 4,4'-diaminodiphenylmethane is purchased from Shanghai Aladdin Biochem Technology Co., Ltd.; sodium azide is purchased from Shanghai Jiachen Chemical Industry Co., Ltd.; 4,4'-oxydianiline is purchased from Tokyo Chemical Industry Co., Ltd.; pyromellitic dianhydride is purchased from Tokyo Chemical Industry Co., Ltd.; N,N-dimethylacetamide is purchased from Shanghai Titan Scientific Co., Ltd.; 3-aminophenylacetylene is purchased from Shanghai Aladdin Biochem Technology Co., Ltd..

[0030] Example 1

[0031] The present embodiment provides a high-heat-dissipation lubricating coating material for the coated aluminum sheet, and the amount of each component is 70 parts of polyimide precursor, 5 parts of silicon dioxide, 3 parts of molybdenum disulfide powder and 70 parts of N,N-dimethylacetamide by weight.

[0032] The preparation process of the polyimide precursor includes the following steps:

[0033] S1, under the protection of nitrogen, 4 mmol of 4,4'-diaminodiphenylmethane is added to a mixture of deionized water and concentrated hydrochloric acid, the reaction mixture is stirred at 3°C, 30 mL of sodium nitrite solution is added dropwise, stirring is continued for 1 h, 10 mL of sodium azide aqueous solution is added dropwise and the reaction is continued for 2 h, the system is filtered after standing for 8 h to obtain 4,4'-diazidodiphenylmethane;

[0034] S2, under the protection of nitrogen, 10 mmol of 4,4'-diazidodiphenylmethane prepared in step S1 and 20 mmol of 3-aminophenylacetylene are dissolved in N,N-dimethylacetamide to form a mixture, 1 mmol of CuSO4·5H2O, 2 mmol of sodium ascorbate and 10 mmol of triethylamine are added in sequence and stirred uniformly, then the temperature is raised to 60°C and the reaction is carried out for 6 hours, then a saturated solution of disodium ethylenediaminetetraacetate is added to form a precipitate, the precipitate is filtered, washed and vacuum dried to obtain intermediate 1;

[0035] S3, under the protection of nitrogen, intermediate 1 prepared in step S2 and 4,4'-oxydianiline are dissolved in N,N-dimethylacetamide to form a mixed solution, pyromellitic dianhydride is added in batches, stirring is carried out at 4°C for 12 h, then a certain amount of acetic anhydride and triethylamine are added for dehydration and cyclization, the product is filtered, washed and vacuum dried to obtain the polyimide precursor; wherein the molar amount ratio of intermediate 1 to 4,4'-oxydianiline is 1:1.

[0036] The embodiment also provides a preparation method of the coating material for coating the aluminum sheet, and the preparation method comprises the following steps: uniformly coating the high-heat-dissipation lubricating coating material on the ground aluminum sheet substrate by using a brushing method, and then performing a defoaming procedure and a thermal imidization procedure to obtain the coating.

[0037] The defoaming procedure comprises the following steps in sequence: 80℃ for 12h, 100℃ for 2h, and 120℃ for 12h.

[0038] The thermal imidization procedure comprises the following steps in sequence: 150℃ for 1h under a nitrogen atmosphere, 200℃ for 1h, 250℃ for 1h, and 300℃ for 1h.

[0039] Embodiment 2

[0040] The embodiment provides a high-heat-dissipation lubricating coating material for coating an aluminum sheet and a preparation method thereof, wherein, compared with the embodiment 1, the molar ratio of the intermediate 1,4,4'-diphenyl ether diamine in step S3 in the preparation process of the polyimide precursor is 1:2, and the rest of the components, the preparation steps and the parameters are consistent.

[0041] Embodiment 3

[0042] The embodiment provides a high-heat-dissipation lubricating coating material for coating an aluminum sheet and a preparation method thereof, wherein, compared with the embodiment 1, the molar ratio of the intermediate 1,4,4'-diphenyl ether diamine in step S3 in the preparation process of the polyimide precursor is 1:3, and the rest of the components, the preparation steps and the parameters are consistent.

[0043] Comparative Example 1

[0044] The comparative example provides a high-heat-dissipation lubricating coating material for coating an aluminum sheet and a preparation method thereof, wherein, compared with the embodiment 1, the molar ratio of the intermediate 1,4,4'-diphenyl ether diamine in step S3 in the preparation process of the polyimide precursor is 1:0.5, and the rest of the components, the preparation steps and the parameters are consistent.

[0045] Comparative Example 2

[0046] The comparative example provides a high-heat-dissipation lubricating coating material for coating an aluminum sheet and a preparation method thereof, wherein, compared with the embodiment 1, the molar ratio of the intermediate 1,4,4'-diphenyl ether diamine in step S3 in the preparation process of the polyimide precursor is 1:4, and the rest of the components, the preparation steps and the parameters are consistent.

[0047] Comparative Example 3

[0048] The comparative example provides a high-heat-dissipation lubricating coating material for coating aluminum sheets and a preparation method thereof. Compared with Example 1, the molar amount ratio of intermediate 1, 4,4'-diphenyl ether diamine in step S3 in the preparation process of the polyimide precursor is 1:0, and the remaining components, preparation steps and parameters are consistent.

[0049] Comparative Example 4

[0050] The comparative example provides a high-heat-dissipation lubricating coating material for coating aluminum sheets and a preparation method thereof. Compared with Example 1, the polyimide precursor is prepared by the following method: under the protection of nitrogen, 4,4'-diphenyl ether diamine is dissolved in N,N-dimethylacetamide to form a mixed solution, 4,4'-diphenyl ether diamine is added in batches, stirred at 4°C for 12h, then a certain amount of acetic anhydride and triethylamine are added for dehydration and cyclization, and the product is filtered, washed and vacuum dried to obtain the polyimide precursor, and the remaining components, preparation steps and parameters are consistent.

[0051] The aluminum sheet samples prepared in the above examples and comparative examples are subjected to the following performance test experiments:

[0052] Drilling test: the aluminum sheet sample is subjected to 0.25mm aperture drilling test for hole wall roughness and hole position accuracy;

[0053] Thermal conductivity test: according to ASTM E1530 coating thermal conductivity test standard;

[0054] Adhesion test: adhesion test is carried out according to GB / T 9286-2021 test standard.

[0055] Table 1: Performance test results

[0056]

[0057] As can be seen from the comparison of the test results of Comparative Examples 1-2 and Example 1-3, by adjusting the relative amount of intermediate 1 and 4,4'-diphenyl ether diamine, the proportion of rigid triazole ring introduced into the film-forming resin polyimide can be controlled. When the molar amount ratio of intermediate 1 and 4,4'-diphenyl ether diamine is in the range of 1:1-3, the coating film can maintain high thermal conductivity while obtaining the best adhesion and drilling quality (low hole wall roughness), achieving the best balance of various performances. As can be seen from the comparison of the test results of Comparative Examples 3-4 and Example 1-3, when only intermediate 1 is used as the diamine raw material, the coating film is rigid and the film-forming effect is poor, resulting in poor adhesion to the substrate, and when only 4,4'-diphenyl ether diamine is used as the raw material, the coating film itself is significantly reduced in thermal conductivity and lubricity.

[0058] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, as long as the changes or modifications do not deviate from the technical solution of the present application. Any indirect modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present application still belong to the scope of the technical solution of the present application.

Claims

1. A high heat dissipating lubricating coating material for an aluminum sheet, characterized by, The amount of each component is 50-70 parts of polyimide precursor, 2-5 parts of filler, 3-5 parts of solid lubricant and 30-100 parts of organic solvent by weight.

2. The high heat dissipating lubricating coating material for an aluminum-coated sheet according to claim 1, characterized by, The preparation process of the polyimide precursor comprises the following steps: S1, under the protection of nitrogen, 4 mmol of 4, 4'-diaminodiphenyl methane is added into a mixture of deionized water and concentrated hydrochloric acid, the reaction mixture is stirred at 3°C, 30 mL of sodium nitrite solution is added dropwise, and after stirring for 1 h, 10 mL of sodium azide aqueous solution is added dropwise and continues to react for 2 h, and after standing for 8 h, the system is filtered to obtain 4, 4'-diazidomethane; S2, under the protection of nitrogen, 10 mmol of 4, 4'-diazidomethane prepared in step S1 and 20 mmol of 3-aminophenylacetylene are dissolved in N, N-dimethylacetamide to form a mixture, and then a proper amount of CuSO4·5H2O, sodium ascorbate and triethylamine are added and stirred uniformly, then heated to 60°C and reacted for 6 hours, then a saturated solution of disodium ethylenediaminetetraacetate is added to form a precipitate, and the precipitate is filtered, washed and vacuum dried to obtain intermediate 1; S3, under the protection of nitrogen, intermediate 1 prepared in step S2 and 4, 4'-diphenyl ether diamine are dissolved in N, N-dimethylacetamide to form a mixed solution, and 4, 4'-diphenyl ether diamine is added in batches, stirred at 4°C for 12 h, then a proper amount of acetic anhydride and triethylamine are added for dehydration and cyclization, and the product is filtered, washed and vacuum dried to obtain the polyimide precursor.

3. The high heat dissipating lubricating coating material for an aluminum-coated sheet according to claim 2, characterized by, The molar amount ratio of intermediate 1 to 4, 4'-diphenyl ether diamine in step S3 is 1:1-3.

4. The high heat dissipating lubricating coating material for an aluminum-coated sheet according to claim 1, characterized by, The solid lubricant is molybdenum disulfide powder with a particle size of 0.5-1.0 μm.

5. The high heat dissipating lubricating coating material for an aluminum-coated sheet according to claim 1, characterized by, The filler is one or more of calcium carbonate, calcined kaolin, mica powder and silicon dioxide.

6. The high heat dissipating lubricating coating material for an aluminum-coated sheet according to claim 1, characterized by, The organic solvent is N, N-dimethylacetamide.

7. A method of producing a high heat dissipating lubricating coating material for an aluminum sheet as claimed in any one of claims 1 to 6, characterized in that, The process comprises the following steps: one of the brushing method, the spin coating method or the dip coating method is used to uniformly coat the high heat dissipation lubricating coating material on the ground aluminum sheet substrate, and then the defoaming procedure and the thermal imidization procedure are carried out to obtain the coating; The defoaming procedure is in turn: 80°C for 12 h, 100°C for 2 h, 120°C for 12 h; The thermal imidization procedure is in turn: under the nitrogen atmosphere, 150°C for 1 h; 200°C for 1 h; 250°C for 1 h; 300°C for 1 h.

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