High-thermal-conductivity insulating aluminum substrate and preparation method thereof

Abstract

The invention discloses a high-thermal-conductivity insulating aluminum substrate and a preparation method thereof, and belongs to the technical field of insulating materials. The high-thermal-conductivity insulating aluminum substrate comprises an aluminum substrate and a thermal conductive coating uniformly coated on the surface of the aluminum substrate; the preparation method of the heat-conducting coating comprises the following steps: adding the modified boron nitride into the epoxy resin, uniformly mixing, adding the epoxy curing agent, the flatting agent, the anti-settling agent, the defoaming agent and the acetone, and uniformly mixing and stirring to obtain the heat-conducting coating. The modified boron nitride is added into the heat-conducting coating, so that the flexibility and corrosion resistance of the heat-conducting coating are remarkably improved, the service life of the heat-conducting coating is prolonged, and the aluminum substrate is well protected.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating materials, and particularly to a highly thermally conductive insulating aluminum substrate and a preparation method thereof. Background Art

[0002] With the rapid development of electronic technology, the integration and power density of electronic devices have been continuously improved, resulting in a significant increase in the heat generated by electronic components during operation. How to effectively conduct these heats quickly to ensure the stable operation of electronic devices has become an important problem to be solved urgently in the field of electronic manufacturing. In this context, highly thermally conductive insulating aluminum substrates have gradually become key materials in the fields of electronic packaging and heat dissipation due to their excellent thermal conductivity and electrical insulation properties.

[0003] The core advantage of the aluminum substrate is that it can quickly transfer the heat generated by electronic components through the insulating layer to the aluminum substrate, and then diffuse it to the external radiator or the environment through the aluminum substrate, thereby effectively reducing the operating temperature of the components and extending their service life.

[0004] Chinese Patent Document CN105062358A provides a highly thermally conductive insulating aluminum substrate. The highly thermally conductive insulating aluminum substrate includes an aluminum plate and a heat dissipation coating layer provided on the surface of the aluminum plate; the heat dissipation coating is mainly made of the following components: by weight, 50 - 75 parts of a methoxy-containing silicone resin, 24 - 43 parts of a filler, and 1 - 3 parts of a coupling agent; the filler is alumina, or a combination of one or more of calcium oxide, zirconium oxide, magnesium oxide, mica and alumina. The highly thermally conductive insulating aluminum substrate of this invention has many advantages such as high thermal conductivity coefficient, excellent insulation, high and low temperature resistance, chemical corrosion resistance, and good compatibility with other materials. However, the heat dissipation coating layer obtained by this patent may be affected by mechanical stress or friction during actual application, and the coating is prone to cracking or peeling, resulting in a decline in the coating performance. Summary of the Invention

[0005] The main object of the present invention is to propose a highly thermally conductive insulating aluminum substrate and a preparation method thereof. By uniformly coating a thermal conductive coating on the surface of the aluminum substrate, the aluminum substrate can be well protected and its service life can be extended.

[0006] To achieve the above object, the present invention proposes a highly thermally conductive insulating aluminum substrate, including an aluminum substrate and a thermal conductive coating uniformly coated on the surface of the aluminum substrate; the preparation method of the thermal conductive coating is: adding modified boron nitride to epoxy resin, mixing evenly and then adding an epoxy curing agent, a leveling agent, an anti-settling agent, an anti-foaming agent and acetone, and mixing and stirring evenly to obtain the thermal conductive coating.

[0007] Preferably, the mass ratio of the modified boron nitride, epoxy resin, epoxy curing agent, leveling agent, anti-settling agent, defoaming agent, and water is 10-20:40-60:3-5:1-2:1-3:1-3:15-25.

[0008] Preferably, the preparation method of the modified boron nitride is as follows:

[0009] 1) Disperse boron nitride in an aqueous sodium hydroxide solution and heat to react to obtain pretreated boron nitride; add the pretreated boron nitride to an aqueous ethanol solution, add vinyl silane coupling agent, and heat and stir to react to obtain vinyl boron nitride; dissolve 4-propenylthiocarbohydrazide in dimethyl sulfoxide, add vinyl boron nitride and initiator, and heat to react to obtain intermediate 1;

[0010] 2) Under a nitrogen atmosphere, dissolve 2-amino-5-methylthiazole in toluene, add hexamethylene diisocyanate and mix evenly, add 1,3-dimethyl-2-imidazolidinone, and heat to react to obtain intermediate 2;

[0011] 3) Mix intermediate 1, intermediate 2, and N,N-dimethylformamide evenly, add dibutyltin dilaurate, adjust the pH value to weakly alkaline, and heat to react under a N2 atmosphere to obtain modified boron nitride.

[0012] Preferably, in step 1), the mass ratio of the pretreated boron nitride, vinyl silane coupling agent, 4-propenylthiocarbohydrazide, and initiator is 15-25:3-5:5-8:0.2-0.5.

[0013] Preferably, in step 2), the mass ratio of 2-amino-5-methylthiazole, hexamethylene diisocyanate, and 1,3-dimethyl-2-imidazolidinone is 1:1-1.5:0.3-0.5.

[0014] Preferably, in step 3), the mass ratio of intermediate 1 and intermediate 2 is 2-4:1.

[0015] The preparation of the modified boron nitride of the present invention is first to treat boron nitride with an alkali to enhance surface activity, and then perform surface treatment with a vinyl silane coupling agent to introduce vinyl groups on its surface, and then graft 4-propenylthiocarbohydrazide onto boron nitride under the action of an initiator to obtain intermediate 1; the amino group on 2-amino-5-methylthiazole reacts with a part of the isocyanate groups on hexamethylene diisocyanate to obtain intermediate 2 with a thiazole group and an aliphatic chain, and finally the surplus isocyanate groups on intermediate 2 react with the amino groups on intermediate 1 to obtain; by modifying boron nitride, the flexibility and anti-corrosion properties of the thermal conductive coating are significantly improved.

[0016] Preferably, the epoxy curing agent is selected from one of 4,4'-diaminodiphenylmethane, 4,4'-diaminodicyclohexylmethane, m-phenylenediamine, and diethyltoluenediamine.

[0017] Preferably, the leveling agent is BYK-111.

[0018] Preferably, the anti-settling agent is at least one of hydrophilic bentonite, silicate, polyamide wax, and montmorillonite.

[0019] Preferably, the defoaming agent is at least one of phosphate ester hydrophobic defoaming agents, polysiloxanes, and organic alcohol compounds.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) By coating the heat-conducting coating on the aluminum substrate, the present invention endows the aluminum substrate with good heat-conducting performance and insulating performance, while enhancing its flexibility and corrosion resistance. By adding modified boron nitride to the heat-conducting coating, it is beneficial to improve the service life of the heat-conducting coating and provide good protection for the aluminum substrate, enabling it to work stably for a long time in high-temperature, high-humidity, and harsh environments, extending the service life of the aluminum substrate, and meeting the requirements for high heat-conducting insulating materials in the fields of electronics, electricity, etc.

[0022] (2) Boron nitride has excellent heat-conducting, insulating, and wear-resistant properties. After being added to the heat-conducting coating through modification treatment, its dispersibility in the epoxy resin matrix is significantly improved, and a more uniform heat-conducting network structure can be formed, thereby greatly enhancing the heat-conducting efficiency of the heat-conducting coating, meeting the high heat-conducting requirements, and significantly improving the wear resistance of the coating, effectively avoiding damage to the coating caused by external force or friction during use and extending the service life of the coating. By grafting 4-allylthiocarbamide on the modified boron nitride, on the one hand, it is beneficial to subsequent reactions, and on the other hand, the thiourea group in its structure can adsorb on the aluminum substrate, inhibiting the reduction reaction occurring at the cathode and effectively blocking the penetration path of the corrosive medium, effectively protecting the aluminum substrate and improving the corrosion resistance of the heat-conducting coating. 2-Amino-5-methylthiazole reacts with hexamethylene diisocyanate to obtain intermediate 2; then the isocyanate group on intermediate 2 further reacts with the amino group on intermediate 1 to graft the intermediate 2 with thiazolyl and aliphatic chains onto boron nitride. The N and S heteroatoms on the thiazolyl can, on the one hand, bind to the metal substrate through coordination to enhance the coating adhesion; on the other hand, they act as electron donors to form a chemical barrier to further inhibit electrochemical corrosion. Its aliphatic chain is beneficial to crosslink with the resin matrix, thereby forming a dense coating, playing a toughening role and further improving the mechanical properties of the heat-conducting coating. Specific embodiments

[0023] To avoid repetition, the items used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0024] The sources of some raw materials used in the present invention are as follows:

[0025] Epoxy resin, grade E44, epoxy value 0.5 eq / 100 g, purchased from Guangzhou Taili Chemical Industry Co., Ltd.

[0026] Boron nitride, hexagonal boron nitride, particle size 1 - 10 μm, model H-BN, purchased from Weifang Zhuoyu New Material Technology Co., Ltd.

[0027] Example 1

[0028] A thermal conductive coating, and its preparation method is: add 15 g of modified boron nitride to 50 g of epoxy resin, after mixing evenly, add 4.2 g of 4,4'-diaminodiphenylmethane, 1.5 g of leveling agent BYK-111, 2 g of polyamide wax micropowder, 2 g of tributyl phosphate and 20 g of acetone, and mix and stir evenly to obtain the thermal conductive coating.

[0029] The preparation method of the modified boron nitride is as follows:

[0030] 1) Disperse 30 g of hexagonal boron nitride in 200 mL of 3 mol / L sodium hydroxide aqueous solution, heat and react at 80 °C for 3 h, cool, filter, collect the solid and wash and dry to obtain pretreated boron nitride; add 20 g of pretreated boron nitride to 200 mL of 50 wt% ethanol aqueous solution, add 4.2 g of vinyltriisopropoxysilane, heat and stir at 50 °C for 4 h, cool, filter, collect the solid and wash and dry to obtain vinyl boron nitride; dissolve 6.8 g of 4-propenylthiocarbazide in 200 mL of dimethyl sulfoxide, add vinyl boron nitride and 0.38 g of ammonium persulfate, heat and react at 80 °C for 5 h, cool, filter, collect the solid and wash and dry to obtain intermediate 1;

[0031] 2) Under a nitrogen atmosphere, dissolve 5 g of 2-amino-5-methylthiazole in 150 mL of toluene, add 6.2 g of hexamethylene diisocyanate and mix evenly, then add 2 g of 1,3-dimethyl-2-imidazolidinone, react at 100 °C for 10 h, after the reaction is completed, add 20 mL of chloroform to fully dissolve the product, then add 15 mL of a mixed solution of cyclohexane and methyl tert-butyl ether with a volume ratio of 1:2, precipitate is generated, filter, collect the solid and dry to obtain intermediate 2;

[0032] 3) Mix 15.6 g of intermediate 1, 5 g of intermediate 2 and 200 mL of N,N-dimethylformamide evenly, add 0.8 g of dibutyltin dilaurate, adjust the pH value to 9, under a N2 atmosphere, heat and react at 80 °C for 30 to obtain modified boron nitride.

[0033] Example 2

[0034] A thermal conductive coating, and its preparation method is as follows: Add 10 g of modified boron nitride to 40 g of epoxy resin, mix evenly, then add 3 g of 4,4'-diaminodiphenylmethane, 1 g of leveling agent BYK-111, 1 g of polyamide wax micropowder, 1 g of tributyl phosphate and 15 g of acetone, and mix and stir evenly to obtain the thermal conductive coating.

[0035] The preparation method of the modified boron nitride is as follows:

[0036] 1) Disperse 30 g of hexagonal boron nitride in 200 mL of 3 mol / L sodium hydroxide aqueous solution, heat and react at 80 °C for 3 h, cool, filter, collect the solid, wash and dry to obtain pretreated boron nitride; Add 15 g of pretreated boron nitride to 200 mL of 50 wt% ethanol aqueous solution, add 3.2 g of vinyltriisopropoxysilane, heat and stir at 50 °C for 4 h, cool, filter, collect the solid, wash and dry to obtain vinyl boron nitride; Dissolve 5 g of 4-propenylthiocarbazide in 200 mL of dimethyl sulfoxide, add vinyl boron nitride and 0.2 g of ammonium persulfate, heat and react at 80 °C for 5 h, cool, filter, collect the solid, wash and dry to obtain intermediate 1;

[0037] 2) Under a nitrogen atmosphere, dissolve 5 g of 2-amino-5-methylthiazole in 150 mL of toluene, add 5 g of hexamethylene diisocyanate and mix evenly, then add 1.5 g of 1,3-dimethyl-2-imidazolidinone, react at 100 °C for 10 h. After the reaction is completed, add 20 mL of chloroform to fully dissolve the product, then add 15 mL of a mixed solution of cyclohexane and methyl tert-butyl ether with a volume ratio of 1:2 to produce precipitation, filter, collect the solid and dry to obtain intermediate 2;

[0038] 3) Mix 10 g of intermediate 1, 5 g of intermediate 2 and 200 mL of N,N-dimethylformamide evenly, add 0.6 g of dibutyltin dilaurate, adjust the pH value to 9, under a N2 atmosphere, heat and react at 80 °C for 30 to obtain modified boron nitride.

[0039] Example 3

[0040] A thermal conductive coating, and its preparation method is as follows: Add 20 g of modified boron nitride to 60 g of epoxy resin, mix evenly, then add 5 g of 4,4'-diaminodiphenylmethane, 2 g of leveling agent BYK-111, 3 g of polyamide wax micropowder, 3 g of tributyl phosphate and 25 g of acetone, and mix and stir evenly to obtain the thermal conductive coating.

[0041] The preparation method of the modified boron nitride is as follows:

[0042] 1) Disperse 30 g of hexagonal boron nitride in 200 mL of 3 mol / L aqueous sodium hydroxide solution, heat and react at 80 °C for 3 h, cool, filter, collect the solid, wash and dry to obtain pretreated boron nitride; add 25 g of pretreated boron nitride to 200 mL of 50 wt% ethanol aqueous solution, add 5 g of vinyltriisopropoxysilane, heat and stir at 50 °C for 4 h, cool, filter, collect the solid, wash and dry to obtain vinyl boron nitride; dissolve 8 g of 4-propenylthiocarbazide in 200 mL of dimethyl sulfoxide, add vinyl boron nitride and 0.5 g of ammonium persulfate, heat and react at 80 °C for 5 h, cool, filter, collect the solid, wash and dry to obtain intermediate 1;

[0043] 2) Under a nitrogen atmosphere, dissolve 5 g of 2-amino-5-methylthiazole in 150 mL of toluene, add 7.5 g of hexamethylene diisocyanate and mix evenly, then add 2.5 g of 1,3-dimethyl-2-imidazolidinone, react at 100 °C for 10 h. After the reaction is completed, add 20 mL of chloroform to fully dissolve the product, then add 15 mL of a mixed solution of cyclohexane and methyl tert-butyl ether with a volume ratio of 1:2 to produce precipitation, filter, collect the solid and dry to obtain intermediate 2;

[0044] 3) Mix 20 g of intermediate 1, 5 g of intermediate 2, and 200 mL of N,N-dimethylformamide evenly, add 1 g of dibutyltin dilaurate, adjust the pH value to 9, under a nitrogen atmosphere, heat and react at 80 °C for 30 to obtain modified boron nitride.

[0045] Comparative Example 1

[0046] A preparation method of a thermal conductive coating is similar to Example 1, the difference is that the modified boron nitride is boron nitride grafted with 4-propenylthiocarbazide, and the specific steps are as follows: add 15 g of modified boron nitride to 50 g of epoxy resin, mix evenly, then add 4.2 g of 4,4'-diaminodiphenylmethane, 1.5 g of leveling agent BYK-111, 2 g of polyamide wax micropowder, 2 g of tributyl phosphate and 20 g of acetone, and mix and stir evenly to obtain the thermal conductive coating.

[0047] The preparation method of the modified boron nitride is as follows:

[0048] Disperse 30 g of hexagonal boron nitride in 200 mL of 3 mol / L aqueous sodium hydroxide solution, heat and react at 80 °C for 3 h, cool, filter, collect the solid, wash and dry to obtain pretreated boron nitride; add 20 g of pretreated boron nitride to 200 mL of 50 wt% ethanol aqueous solution, add 4.2 g of vinyltriisopropoxysilane, heat and stir at 50 °C for 4 h, cool, filter, collect the solid, wash and dry to obtain vinyl boron nitride; dissolve 6.8 g of 4 - propenylthiocarbazide in 200 mL of dimethyl sulfoxide, add vinyl boron nitride and 0.38 g of ammonium persulfate, heat and react at 80 °C for 5 h, cool, filter, collect the solid, wash and dry to obtain modified boron nitride.

[0049] Comparative Example 2

[0050] A preparation method of a thermal conductive coating is similar to Example 1, the difference is that the boron nitride is not modified, and the specific steps are as follows: add 15 g of hexagonal boron nitride to 50 g of epoxy resin, mix evenly, then add 4.2 g of 4,4'-diaminodiphenylmethane, 1.5 g of leveling agent BYK - 111, 2 g of polyamide wax micropowder, 2 g of tributyl phosphate and 20 g of acetone, and mix and stir evenly to obtain the thermal conductive coating.

[0051] Performance test

[0052] Clean and dry the aluminum substrate, and then stir the thermal conductive coatings prepared in Examples 1 - 3 and Comparative Examples 1 - 2 at room temperature for 5 minutes, and then evenly spray them onto the aluminum substrate. The spraying thickness is 100 μm, and cure at 25 °C for 5 days to obtain the coatings for testing.

[0053] Thermal conductivity test: Use the TPS2200 thermal constant analyzer of HotDiSk Company in Sweden to test the thermal conductivity of the coating samples;

[0054] Flexibility test: Refer to GB / T1731 - 2020 "Determination method for flexibility of paint films and putty films" for testing;

[0055] Wear resistance test: Refer to GB / T 1768 - 2006 "Determination of abrasion resistance of paints and varnishes - Rotating rubber wheel method";

[0056] Corrosion resistance test: Refer to GB / T 31588.1 - 2015 "Determination of resistance of paints and varnishes to cyclic corrosion environments - Part 1: Humid (salt spray) / dry / moisture";

[0057] Insulation performance test: Refer to GB1408.1 - 2016 "Test method for electrical strength of insulating materials - Part 1: Tests at power frequency", and use the GJW - 50KV voltage breakdown tester of Changchun Intelligent Instrument and Equipment Co., Ltd. for testing. The test results are shown in Table 1:

[0058] Table 1 Performance test results of the thermal conductive coating

[0059]

[0060] It can be seen from the experimental results in Table 1 that the thermal conductive coating prepared in this application has good heat dissipation, flexibility, wear resistance, corrosion resistance and insulation properties.

[0061] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A high thermal conductivity insulating aluminum substrate, characterized in that: The invention comprises an aluminum substrate and a thermal conductive coating uniformly coated on the surface of the aluminum substrate; the preparation method of the thermal conductive coating comprises: adding modified boron nitride to epoxy resin, adding epoxy curing agent, leveling agent, anti-settling agent, defoaming agent and acetone after mixing, and mixing and stirring uniformly to obtain the thermal conductive coating.

2. The high thermal conductivity insulating aluminum substrate according to claim 1, characterized in that: The mass ratio of the modified boron nitride, epoxy resin, epoxy curing agent, leveling agent, anti-settling agent, defoaming agent and water is 10-20:40-60:3-5:1-2:1-3:1-3:15-25.

3. The high thermal conductivity insulating aluminum substrate according to claim 2, characterized in that: The preparation method of the modified boron nitride is as follows: 1) dispersing boron nitride in a sodium hydroxide aqueous solution and heating for reaction to obtain pretreated boron nitride; adding the pretreated boron nitride to an ethanol aqueous solution, adding a vinyl silane coupling agent, heating and stirring for reaction to obtain vinyl boron nitride; dissolving 4-propylene thiosemicarbazide in dimethyl sulfoxide, adding vinyl boron nitride and an initiator, and heating for reaction to obtain an intermediate 1; 2) Under a nitrogen atmosphere, 2-amino-5-methylthiazole was dissolved in toluene, hexamethylene diisocyanate was added and mixed evenly, 1,3-dimethyl-2-imidazolidinone was added, and the mixture was heated to react to obtain intermediate 2; 3) The intermediate 1, the intermediate 2 and N,N-dimethylformamide are uniformly mixed, dibutyltin laurate is added, the pH value is adjusted to be weakly alkaline, and the mixture is heated to react in a N2 atmosphere to obtain modified boron nitride.

4. The high thermal conductivity insulating aluminum substrate according to claim 3, characterized in that: In the step 1), the mass ratio of pretreated boron nitride, vinyl silane coupling agent, 4-propylene thiosemicarbazide and initiator is 15-25:3-5:5-8:0.2-0.

5.

5. The high thermal conductivity insulating aluminum substrate according to claim 3, characterized in that: In the step 2), the mass ratio of the 2-amino-5-methylthiazole, hexamethylene diisocyanate, and 1,3-dimethyl-2-imidazolidinone is 1:1-1.5:0.3-0.

5.

6. The high thermal conductivity insulating aluminum substrate according to claim 3, characterized in that: The mass ratio of the intermediate 1 to the intermediate 2 is 2-4:

1.

7. The high thermal conductivity insulating aluminum substrate according to claim 1 or 2, characterized in that: The epoxy curing agent is selected from one of 4,4'-diaminodiphenylmethane, 4,4'-diaminodicyclohexylmethane, meta-phenylenediamine and diethyltoluenediamine.

8. The highly thermally conductive insulating aluminum substrate according to claim 1 or 2, characterized in that: The leveling agent is BYK-111.

9. The high thermal conductivity insulating aluminum substrate according to claim 1 or 2, characterized in that: The anti-settling agent is at least one of hydrophilic bentonite, silicate, polyamide wax and montmorillonite.

10. The high thermal conductivity insulating aluminum substrate according to claim 1 or 2, characterized in that: The defoaming agent is at least one of a phosphate hydrophobic defoaming agent, polysiloxane, and an organic alcohol compound.

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