Hydrolysis-resistant heat-conductive polyurethane potting adhesive and preparation method thereof

Abstract

The present invention belongs to the technical field of polyurethane potting glue, and specifically relates to a hydrolysis-resistant heat-conductive polyurethane potting glue and a preparation method thereof. The hydrolysis-resistant heat-conductive polyurethane potting glue of the present invention is made of component A and component B in a mass ratio of 100: (18.5-20.5), and component A includes the following raw materials: amine ether polyol, modified castor oil, flame retardant, heat-conductive filler, silane coupling agent, catalyst; component B includes the following raw materials: polymerized MDI, MDI-50, carbodiimide-modified MDI; the amine ether polyol is prepared by reacting 3,3'-dimethyl-4,4'diaminodiphenylmethane and propylene oxide. The hydrolysis-resistant heat-conductive polyurethane potting glue of the present invention not only has good process operation performance and thermal conductivity, but also has excellent hydrolysis resistance, and still has good mechanical properties and electrical insulation properties after aging; the present invention also provides a scientific, reasonable, simple and easy preparation method.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane potting adhesives, and in particular relates to a hydrolysis-resistant heat-conducting polyurethane potting adhesive and a preparation method thereof. Background Art

[0002] As an important thermal conductive potting material, polyurethane products have both the strength of epoxy products and the toughness of silicone products. They have been widely used in new energy vehicle power batteries, electronic appliances and other fields. With the rapid development of the industry, the above industries have put forward higher requirements on the high temperature resistance and hydrolysis resistance of the products. However, the comprehensive performance of polyurethane products is currently difficult to fully meet the actual needs of the industry.

[0003] The main process requirements of thermal conductive polyurethane potting glue are: lower material viscosity and longer operation time. Only when the above process requirements are met can all gaps be fully filled with materials. However, electronic or battery products are generally not heated for curing. Longer operation time is generally achieved by reducing the amount of catalyst added. However, reducing the amount of catalyst added will lead to lower final strength of room temperature curing (generally the performance after 7 days of room temperature curing is the final performance). Although it can meet the mechanical performance requirements, insufficient reaction will lead to poor hydrolysis resistance of the product.

[0004] CN117447958A discloses a high temperature resistant and aging resistant heat conductive polyurethane structural adhesive and a preparation method thereof. The raw materials consist of component A and component B. Component A uses an amine ether polyol made by reacting 4,4'-diaminodiphenylmethane and propylene oxide; component B uses a prepolymer made from polyester polyol, 1,5-naphthalene diisocyanate, diphenylmethane diisocyanate, and carbodiimide modified isocyanate. The polyurethane structural adhesive finally prepared has not only good thermal conductivity, adhesion and flexibility, but also excellent high temperature resistance and aging resistance. It still has good adhesion and toughness under high temperature and long-term aging conditions. However, the amine ether polyol used in the patent has small steric hindrance, high activity, and short operation time, and is not suitable for use as a potting adhesive.

[0005] CN118931466A discloses a low-hardness, high-toughness, hydrolysis-resistant insulating polyurethane potting glue and a preparation method thereof. Castor oil polyol, bio-based polyol, hydrolysis-resistant polyester polyol, defoamer, pigment, and additive are component A, and MDI-50 diphenylmethane diisocyanate, castor oil polyol, bio-based polyol, hydrolysis-resistant polyester polyol, and chain extender are component B. By adjusting the formula, the prepared polyurethane potting glue has high toughness and hydrolysis resistance, as well as good tensile strength and insulation. The patent adopts hydrolysis-resistant polyester polyol to improve the hydrolysis resistance of the potting glue, but the hydrolysis resistance effect provided by the hydrolysis-resistant polyester polyol is limited and is significantly lower than that of the polyether polyol system. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a hydrolysis-resistant thermally conductive polyurethane potting glue, which not only has good process operation performance and thermal conductivity, but also has excellent hydrolysis resistance, and still has good mechanical properties and electrical insulation properties after aging; the present invention also provides a scientific, reasonable, simple and easy preparation method.

[0007] The hydrolysis-resistant heat-conductive polyurethane potting adhesive of the present invention is prepared from component A and component B in a mass ratio of 100:(18.5-20.5), wherein component A includes the following raw materials in parts by mass:

[0008] Amine ether polyol: 8-20 parts;

[0009] Modified castor oil: 15-30 parts;

[0010] Flame retardant: 2-5 parts;

[0011] Thermal conductive filler: 80-90 parts;

[0012] Silane coupling agent: 0.5-2.0 parts;

[0013] Catalyst: 0.01-0.06 parts;

[0014] Component B includes the following raw materials in parts by weight:

[0015] Polymeric MDI: 30-90 parts;

[0016] MDI-50: 5-30 parts;

[0017] Carbodiimide modified MDI: 5-50 parts.

[0018] The amine ether polyol is prepared by the reaction of 3,3'-dimethyl-4,4'-diaminodiphenylmethane (MDT) and propylene oxide, has a functionality of 4 and a number average molecular weight of 775-835.

[0019] The specific preparation method of the amine ether polyol is as follows: raw materials are prepared according to a molar ratio of 3,3'-dimethyl-4,4'-diaminodiphenylmethane to propylene oxide of 1:(9.5-10.5); after ensuring that the reaction container is dry and free of impurities, all 3,3'-dimethyl-4,4'-diaminodiphenylmethane is added to the reaction container; stirring is started and the temperature is raised to 120-135° C.; 20-30wt.% of the total amount of propylene oxide is added to the reaction container to start the reaction; when the pressure of the reaction container drops to 0.15MPa, heating is stopped, the remaining propylene oxide is added, the temperature is controlled not to exceed 110° C., and the reaction is carried out at 95-105° C. for 24-30 hours to obtain the polyol.

[0020] The modified castor oil is A4130 produced by Shanghai Jingri New Material Technology Co., Ltd.

[0021] The flame retardant is resorcinol bis(diphenyl phosphate), preferably WSFR-RDP produced by Zhejiang Wansheng Co., Ltd.

[0022] The thermal conductive filler is one or both of aluminum oxide and aluminum hydroxide, preferably GD-S117G produced by Guangdong Jinge New Materials Co., Ltd.

[0023] The silane coupling agent is one or more of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane, preferably γ-glycidyloxypropyltrimethoxysilane (KH-560).

[0024] The catalyst is one or more of a bismuth catalyst, a zinc catalyst, an amine catalyst and a tin catalyst, preferably bismuth neodecanoate (CB-18) among the bismuth catalysts.

[0025] The polymeric MDI is preferably PM-200 produced by Yantai Wanhua Chemical Group Co., Ltd., the MDI-50 is preferably MDI-50 produced by Yantai Wanhua Chemical Group Co., Ltd., and the carbodiimide-modified MDI is preferably CD-C produced by Covestro Polymers China Ltd.

[0026] The method for preparing the hydrolysis-resistant thermally conductive polyurethane potting adhesive comprises the following steps:

[0027] (1) Preparation of component A: Add amine ether polyol, modified castor oil, flame retardant, thermal conductive filler and silane coupling agent into a planetary mixer, heat to 100-110°C, vacuum dehydrate for 2-3h, cool to 50-70°C, add catalyst, stir evenly, and obtain component A;

[0028] (2) Preparation of component B: Add polymerized MDI, MDI-50, and carbodiimide-modified MDI into a planetary mixer, heat to 50-70°C, and stir evenly to obtain component B;

[0029] (3) When in use, mix component A and component B and leave them at room temperature to obtain a hydrolysis-resistant thermally conductive polyurethane potting adhesive.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The hydrolysis-resistant thermally conductive polyurethane encapsulant of the present invention adopts amine ether polyol as a raw material. The amine ether polyol is prepared by reacting propylene oxide with MDT as an initiator. The molecular structure contains a tertiary amine structure and has self-catalytic reaction activity. At the same time, the methyl group ortho to the amine group of the initiator MDT has a certain steric hindrance effect, which can appropriately delay the catalytic activity of the tertiary amine structure. This special amine ether polyol allows the product to have a long operating time at room temperature and can be cured at room temperature for 7 days without high-temperature vulcanization. The reaction is fully carried out and the product has excellent hydrolysis resistance.

[0032] (2) The hydrolysis-resistant thermally conductive polyurethane potting adhesive of the present invention contains a benzene ring structure with good high temperature resistance in the amine ether polyol, and the product has a high functionality. It is used in combination with low-viscosity modified castor oil, high-functionality isocyanate, and flame retardant. The product has a high degree of cross-linking, which further improves the hydrolysis resistance of the product. The use of low-viscosity raw materials makes the final prepared product have good fluidity and can fully meet the process operation performance.

[0033] (3) The preparation method of the hydrolysis-resistant thermally conductive polyurethane potting adhesive of the present invention has a simple and reasonable process, and the raw materials are readily available, which is convenient for industrial production. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the examples. The raw materials used in the examples and comparative examples are conventional commercially available raw materials unless otherwise specified. The process methods used are conventional methods in the art unless otherwise specified. The parts of the raw materials in the examples and comparative examples are all parts by mass.

[0035] The raw materials used in the embodiments and comparative examples are described as follows:

[0036] A4130: modified castor oil, hydroxyl value 230, functionality 3.9, Shanghai Jingri New Material Technology Co., Ltd.

[0037] BMY: refined castor oil, hydroxyl value 165, functionality 2.7, Dongying Shunli Biotechnology Co., Ltd.;

[0038] WSFR-RDP: resorcinol bis(diphenyl phosphate), Zhejiang Wansheng Co., Ltd.;

[0039] GD-S117G: thermal conductive filler, with alumina as the main component, Guangdong Jinge New Materials Co., Ltd.;

[0040] KH-560: γ-glycidyloxypropyltrimethoxysilane, Eastman Technology Co., Ltd.;

[0041] CB-18: catalyst, bismuth neodecanoate, Taixing Shengling Co., Ltd.;

[0042] PM-200: polymeric MDI, Yantai Wanhua Chemical Group Co., Ltd.;

[0043] MDI-50: Yantai Wanhua Chemical Group Co., Ltd.

[0044] CD-C: Carbodiimide modified MDI, Covestro Polymers China Co., Ltd.

[0045] The amine ether polyols used in the examples and comparative examples are described as follows:

[0046] Using 3,3'-dimethyl-4,4'-diaminodiphenylmethane and propylene oxide as raw materials, the number average molecular weight of the prepared amine ether polyol is 805±30, the functionality is 4, and the molar ratio of the raw material 3,3'-dimethyl-4,4'-diaminodiphenylmethane and propylene oxide is between 1: (9.5-10.5), and the obtained product indicators are all within the required range. Therefore, taking the molar ratio of 3,3'-dimethyl-4,4'-diaminodiphenylmethane and propylene oxide as 1:10 as an example to prepare amine ether polyol, the specific preparation process is as follows:

[0047] After ensuring that the reaction container is dry and free of impurities, add all the 3,3'-dimethyl-4,4'-diaminodiphenylmethane into the reaction container, start stirring and raise the temperature to 130°C, add 20wt.% of the total amount of propylene oxide into the reaction container to start the reaction, and when the pressure of the reaction container drops to 0.15MPa, stop heating, add the remaining propylene oxide, control the temperature not to exceed 110°C, and react at 100±5°C for 24h to obtain amine ether polyol with a number average molecular weight of 805 and a functionality of 4, which meet the required range.

[0048] The method for preparing the hydrolysis-resistant thermally conductive polyurethane potting adhesive comprises the following steps:

[0049] (1) Preparation of component A: 8-20 parts of amine ether polyol, 15-30 parts of modified castor oil, 2-5 parts of flame retardant, 80-90 parts of thermal conductive filler and 0.5-2.0 parts of silane coupling agent are added to a planetary mixer, heated to 100-110°C, vacuum dehydrated for 2-3 hours, cooled to 50-70°C, and then 0.01-0.06 parts of catalyst are added, and vacuum stirred to obtain component A;

[0050] (2) Preparation of component B: Add 30-90 parts of polymeric MDI, 5-30 parts of MDI-50, and 5-50 parts of carbodiimide-modified MDI into a planetary mixer, heat to 50-70°C, and stir evenly under vacuum to obtain component B;

[0051] (3) When in use, mix component A and component B in a mass ratio of 100:(18.5-20.5) and place them at room temperature for 7 days to obtain a hydrolysis-resistant thermally conductive polyurethane potting adhesive.

[0052] Example 1

[0053] The method for preparing the hydrolysis-resistant thermally conductive polyurethane potting adhesive comprises the following steps:

[0054] (1) Preparation of component A: by weight, add 15 parts of amine ether polyol, 25 parts of modified castor oil A4130, 3 parts of flame retardant WSFR-RDP, 85 parts of thermal conductive filler GD-S117G, and 1 part of silane coupling agent KH-560 into a planetary mixer, heat to 100°C, vacuum dehydrate for 2 hours, and then add 0.02 parts of catalyst CB-18 after cooling to 50°C. Vacuum stir and obtain component A.

[0055] (2) Preparation of component B: Add 70 parts by mass of PM-200, 20 parts by mass of MDI-50 and 10 parts by mass of CD-C into a planetary mixer, heat to 50°C, and stir in vacuum to obtain component B.

[0056] (3) When in use, mix component A and component B in a mass ratio of 100:20 and leave at room temperature for 7 days to obtain a hydrolysis-resistant thermally conductive polyurethane potting adhesive.

[0057] Example 2

[0058] The method for preparing the hydrolysis-resistant thermally conductive polyurethane potting adhesive comprises the following steps:

[0059] (1) Preparation of component A: by weight, add 15 parts of amine ether polyol, 25 parts of modified castor oil A4130, 3 parts of flame retardant WSFR-RDP, 85 parts of thermal conductive filler GD-S117G, and 1 part of silane coupling agent KH-560 into a planetary mixer, heat to 105°C, vacuum dehydrate for 3 hours, and then add 0.02 parts of catalyst CB-18 after cooling to 70°C. Vacuum stir to obtain component A;

[0060] (2) Preparation of component B: Add 90 parts by mass of PM-200, 5 parts by mass of MDI-50 and 5 parts by mass of CD-C into a planetary mixer, heat to 70°C, and stir in vacuum to obtain component B.

[0061] (3) When in use, mix component A and component B in a mass ratio of 100:20.3 and leave at room temperature for 7 days to obtain a hydrolysis-resistant thermally conductive polyurethane potting adhesive.

[0062] Example 3

[0063] The method for preparing the hydrolysis-resistant thermally conductive polyurethane potting adhesive comprises the following steps:

[0064] (1) Preparation of component A: by weight, add 15 parts of amine ether polyol, 25 parts of modified castor oil A4130, 3 parts of flame retardant WSFR-RDP, 85 parts of thermal conductive filler GD-S117G, and 1 part of silane coupling agent KH-560 into a planetary mixer, heat to 110°C, vacuum dehydrate for 2 hours, cool to 60°C, add 0.04 parts of catalyst CB-18, and vacuum stir to obtain component A;

[0065] (2) Preparation of component B: Add 30 parts by mass of PM-200, 20 parts by mass of MDI-50 and 50 parts by mass of CD-C into a planetary mixer, heat to 60°C, and stir evenly under vacuum to obtain component B;

[0066] (3) When in use, mix component A and component B in a mass ratio of 100:20.5 and leave at room temperature for 7 days to obtain a hydrolysis-resistant thermally conductive polyurethane potting adhesive.

[0067] Example 4

[0068] The method for preparing the hydrolysis-resistant thermally conductive polyurethane potting adhesive comprises the following steps:

[0069] (1) Preparation of component A: by weight, add 8 parts of amine ether polyol, 30 parts of modified castor oil A4130, 5 parts of flame retardant WSFR-RDP, 80 parts of thermal conductive filler GD-S117G, and 2 parts of silane coupling agent KH-560 into a planetary mixer, heat to 100°C, vacuum dehydrate for 2 hours, and then add 0.06 parts of catalyst CB-18 after cooling to 65°C. Vacuum stir to obtain component A;

[0070] (2) Preparation of component B: Add 60 parts by mass of PM-200, 30 parts by mass of MDI-50 and 10 parts by mass of CD-C into a planetary mixer, heat to 65°C, and stir in vacuum to obtain component B.

[0071] (3) When in use, mix component A and component B in a mass ratio of 100:19 and leave them at room temperature for 7 days to obtain a hydrolysis-resistant thermally conductive polyurethane potting adhesive.

[0072] Example 5

[0073] The method for preparing the hydrolysis-resistant thermally conductive polyurethane potting adhesive comprises the following steps:

[0074] (1) Preparation of component A: By weight, 20 parts of homemade amine ether polyol, 15 parts of modified castor oil A4130, 2 parts of flame retardant WSFR-RDP, 90 parts of thermal conductive filler GD-S117G, and 0.5 parts of silane coupling agent KH-560 were added to a planetary mixer, heated to 100°C, vacuum dehydrated for 2 hours, and then cooled to 70°C, 0.01 parts of catalyst CB-18 were added, and vacuum stirred to obtain component A;

[0075] (2) Preparation of component B: Add 70 parts by mass of PM-200, 20 parts by mass of MDI-50 and 10 parts by mass of CD-C into a planetary mixer, heat to 70°C, and stir in vacuum to obtain component B.

[0076] (3) When in use, mix component A and component B in a mass ratio of 100:18.5 and leave them at room temperature for 7 days to obtain a hydrolysis-resistant thermally conductive polyurethane potting adhesive.

[0077] Comparative Example 1

[0078] This comparative example is the same as Example 1, except that the amine ether polyol in component A is replaced by an equal amount of common polyether R408 (prepared by reacting pentaerythritol as an initiator with propylene oxide in a molar ratio of 1:17.5, with the same preparation process as the amine ether polyol, the product functionality is 4, and the number average molecular weight is 800), and the amount of catalyst CB-18 is increased from 0.02 parts to 0.05 parts. Other than that, it is the same as Example 1.

[0079] Comparative Example 2

[0080] This comparative example is the same as Example 1, except that the modified castor oil A4130 in component A is replaced by unmodified refined BMY (hydroxyl value 165, functionality 2.7, Dongying Shunli Biotechnology Co., Ltd.) of equal mass, the amount of thermal conductive filler is changed to 80 parts, and when used, the mass ratio of component A to component B is changed to 100:17.3. Other than that, it is the same as Example 1.

[0081] Comparative Example 3

[0082] This comparative example is the same as Example 1, except that the isocyanate in component B is all MDI-50. When used, the mass ratio of component A to component B becomes 100:22.3. Other than that, it is the same as Example 1.

[0083] The hydrolysis-resistant thermally conductive polyurethane potting adhesives prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to performance tests. The thermal conductivity was tested according to GB / T10294-2008; the tensile strength was tested according to GB / T528-2009; and the volume resistivity was tested according to GB / T1410-2006. The results are shown in Table 1.

[0084] Table 1 Test results

[0085]

[0086] From the data in the table, it can be seen that the thermal conductivity of the polyurethane thermal conductive potting glue products prepared in Examples 1-5 is adjustable within the range of 0.71-0.90 W / (m·K). After the samples were immersed in 70°C hot water for 1000 hours, the tensile strength retention rate was above 90%, and the volume resistivity was greater than 10 12 Ω·cm.

[0087] Compared with Example 1, Comparative Example 1 uses PPG polyether with the same functionality and similar molecular weight to replace amine ether polyol. Due to the low activity of PPG polyether, it is necessary to increase the amount of catalyst to achieve a similar operating time. The tensile strength and volume resistivity of the product after hydrolysis are severely reduced, making it difficult to meet the hydrolysis resistance requirements of the product.

[0088] Compared with Example 1, Comparative Example 2 uses ordinary unmodified refined castor oil, and the amount of thermal conductive filler remains the same as that in Example 1. The tensile strength and volume resistivity of the sample after hydrolysis are severely reduced, which is mainly caused by the low functionality and insufficient cross-linking degree of ordinary refined castor oil.

[0089] Compared with Example 1, the isocyanate in Comparative Example 3 is all MDI-50. Due to the low activity and functionality, the tensile strength and volume resistivity of the product after hydrolysis are seriously reduced.

Claims

1. A hydrolysis-resistant thermally conductive polyurethane potting adhesive, characterized in that: It is made of component A and component B in a mass ratio of 100: (18.5-20.5), wherein component A includes the following raw materials in mass fractions: Amine ether polyol: 8-20 parts; Modified castor oil: 15-30 parts; Flame retardant: 2-5 parts; Thermal conductive filler: 80-90 parts; Silane coupling agent: 0.5-2.0 parts; Catalyst: 0.01-0.06 parts; Component B includes the following raw materials in parts by weight: Polymeric MDI: 30-90 parts; MDI-50: 5-30 parts; Carbodiimide modified MDI: 5-50 parts; The amine ether polyol is prepared by the reaction of 3,3'-dimethyl-4,4'diaminodiphenylmethane and propylene oxide, has a functionality of 4 and a number average molecular weight of 775-835; The modified castor oil is A4130.

2. The hydrolysis-resistant thermally conductive polyurethane potting adhesive according to claim 1, characterized in that: The molar ratio of 3,3'-dimethyl-4,4'-diaminodiphenylmethane to propylene oxide in the amine ether polyol is 1:(9.5-10.5).

3. The hydrolysis-resistant thermally conductive polyurethane potting adhesive according to claim 1, characterized in that: The flame retardant is resorcinol bis(diphenyl phosphate).

4. The hydrolysis-resistant thermally conductive polyurethane potting adhesive according to claim 1, characterized in that: The thermal conductive filler is one or both of aluminum oxide and aluminum hydroxide.

5. The hydrolysis-resistant thermally conductive polyurethane potting adhesive according to claim 1, characterized in that: The silane coupling agent is one or more of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane.

6. The hydrolysis-resistant thermally conductive polyurethane potting adhesive according to claim 1, characterized in that: The catalyst is one or more of a bismuth catalyst, a zinc catalyst, an amine catalyst and a tin catalyst.

7. A method for preparing the hydrolysis-resistant thermally conductive polyurethane potting adhesive according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Preparation of component A: Add amine ether polyol, modified castor oil, flame retardant, thermal conductive filler and silane coupling agent into a planetary mixer, heat to 100-110°C, vacuum dehydrate for 2-3h, cool to 50-70°C, add catalyst, stir evenly, and obtain component A; (2) Preparation of component B: Add polymerized MDI, MDI-50, and carbodiimide-modified MDI into a planetary mixer, heat to 50-70°C, and stir evenly to obtain component B; (3) When in use, mix component A and component B and leave them at room temperature to obtain a hydrolysis-resistant thermally conductive polyurethane potting adhesive.

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