High-temperature and hydrolysis resistant heat-conducting polyurethane structural adhesive and preparation method thereof

Abstract

The application belongs to the technical field of polyurethane adhesive, and particularly relates to a heat-conducting polyurethane structural adhesive with high temperature resistance and hydrolysis resistance and a preparation method thereof. The structural adhesive comprises component A and component B. Component A comprises the following raw materials in parts by weight: polyhydric alcohol 5.0-6.5 parts, castor oil 19.0-21.0 parts, heat-conducting filler 70.0-72.0 parts, thixotropic agent 0.1-1.0 parts, silane coupling agent 0.5-1.0 parts, water absorption agent 0-5.0 parts, and catalyst 0.1-0.3 parts. Component B comprises the following raw materials in parts by weight: isocyanate 17.0-21.0 parts, polyester polyol 5.0-10.0 parts, water removal agent 0.1-0.3 parts, heat-conducting filler 70.0-72.0 parts, thixotropic agent 0.1-1.0 parts, and inhibitor 0.01-0.5 parts. The application improves the high temperature resistance, has a long operation time, and has high toughness, elongation and hydrolysis resistance.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane adhesive technology, specifically relating to a high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive and its preparation method. Background Technology

[0002] In recent years, with the rapid development of the new energy industry, the new energy vehicle industry has also experienced rapid growth. As the heart of new energy vehicles, the power battery pack faces increasingly stringent requirements regarding materials, structure, and performance. Thermally conductive polyurethane structural adhesive is a crucial component of the power battery pack, and the requirements for its performance stability, aging resistance, and hydrolysis properties are also becoming increasingly stringent.

[0003] Chinese invention patent application publication number CN115612438A discloses a thermally conductive polyurethane structural adhesive for improving high-temperature retention. This thermally conductive structural adhesive has good high-temperature resistance, but in practical applications, it suffers from low toughness and short operating time.

[0004] Chinese invention patent application publication number CN115785879A discloses a flame-retardant and high-temperature resistant two-component polyurethane structural adhesive. The isocyanate in this patent is mainly highly active MDI-100 or PM200, which results in a short system operation time and cannot meet the on-site operation requirements. At the same time, this patent is a low thermal conductivity polyurethane structural adhesive, and there is a lot of room for improvement in thermal conductivity. In addition, the amount of filler added is large, making it difficult to guarantee the toughness and mechanical properties of the product.

[0005] Currently, thermally conductive polyurethane structural adhesives mostly improve high-temperature resistance by using bisphenol A polyether, aspartic acid, or amine chain extenders. Among them, bisphenol A polyether has a generally poor high-temperature resistance effect, while aspartic acid or amine chain extenders have high reactivity and rigidity. Adding a small amount has little effect, while adding a large amount can lead to brittleness and poor toughness. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive, which improves high-temperature resistance, extends working time, and exhibits high toughness, elongation, and hydrolysis resistance. This invention also provides a preparation method that is simple and efficient in production.

[0007] The high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive of the present invention comprises component A and component B in a weight ratio of 100:(90~110);

[0008] Component A comprises the following raw materials in parts by weight:

[0009] 5.0-6.5 parts of polyol,

[0010] Castor oil 19.0~21.0 parts,

[0011] 70.0~72.0 parts of thermally conductive filler.

[0012] Thixotropic agent 0.1~1.0 parts,

[0013] 0.5~1.0 parts of silane coupling agent,

[0014] Water absorbent 0-5.0 parts,

[0015] Catalyst 0.1~0.3 parts;

[0016] Component B contains the following parts by weight of raw materials:

[0017] Isocyanate 17.0~21.0 parts,

[0018] Polyester polyol 5.0~10.0 parts,

[0019] Water-removing agent 0.1~0.3 parts,

[0020] 70.0~72.0 parts of thermally conductive filler.

[0021] Thixotropic agent 0.1~1.0 parts,

[0022] Inhibitor 0.01~0.5 parts.

[0023] Preferably, the polyol is a mixture of polyether polyol and amine ether polyol; the polyether polyol has a functionality of 3 and a number-average molecular weight of 300-500; the amine ether polyol is prepared by reacting diethyltoluene diamine and propylene oxide, has a functionality of 4, and a number-average molecular weight of 300-500.

[0024] Preferably, the amine ether polyol is prepared by reacting diethyltoluene diamine and propylene oxide in a molar ratio of 1:(2.1~2.3).

[0025] The preparation method of amine ether polyol is as follows: Diethyltoluene diamine is added to a reaction vessel, and after N2 replacement, stirring is started and the temperature is raised to 90°C. 15%~20% of the total amount of propylene oxide is added to the reaction vessel to start the reaction. When the pressure in the vessel drops from 0.3~0.4 MPa to 0.15 MPa, heating is stopped, and cooling water is circulated to prevent overheating. The remaining propylene oxide is added to the reaction vessel, and the temperature is controlled not to exceed 110°C. The reaction is carried out at 95~105°C. When the pressure in the vessel drops to about zero, the reaction vessel is cooled down. After cooling to room temperature, a sample is taken for analysis. If it is qualified, the material is discharged.

[0026] Further preferred, the polyether polyol is DV125 produced by Shandong Lanxing Dongda Co., Ltd.

[0027] Further preferred, the amine ether polyol is E403 produced by Shandong Yinuowei Polyurethane Co., Ltd.

[0028] Preferably, the thermally conductive filler is one or more of alumina, aluminum hydroxide, and magnesium hydroxide; more preferably, it is JAZ-058 produced by Guangdong Jingge New Materials Co., Ltd.

[0029] Preferably, the thixotropic agent is a hydrophobic fumed silica silane; more preferably, it is XH-202 produced by Evonik Specialty Chemicals (Shanghai) Co., Ltd.

[0030] Preferably, the coupling agent is one or more of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane.

[0031] Preferably, the water absorbent is 3A molecular sieve; more preferably, it is XS-3A produced by Lianhaixin Chemical Co., Ltd.

[0032] Preferably, the dehydrating agent is p-toluenesulfonyl isocyanate (TI).

[0033] Preferably, the catalyst is one or more of bismuth catalysts, zinc catalysts and tin catalysts; more preferably, it is dibutyltin dilaurate.

[0034] Preferably, the isocyanate is one or both of isoflurane diisocyanate (IPDI) and dicyclohexylmethane diisocyanate (HMDI).

[0035] Preferably, the inhibitor is N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine.

[0036] Preferably, the polyester polyol is one or both of PE-2000IS and PE-1000IS produced by Shandong Yinuowei Polyurethane Co., Ltd.

[0037] The preparation method of the high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive of the present invention includes the following steps:

[0038] (1) Preparation of component A:

[0039] Add the polyol, castor oil, thermally conductive filler, and silane coupling agent from component A into the reactor, heat to 100-110℃, dehydrate to less than 0.5‰, cool to room temperature, and then add thixotropic agent, water absorbent, and catalyst. Stir for 1-2 hours to obtain component A.

[0040] (2) Preparation of component B:

[0041] First, the polyester polyol, isocyanate and inhibitor are mixed and heated to 90~95℃ and kept at that temperature for 3~5 hours. After cooling to room temperature, a dehydrating agent is added to obtain a prepolymer with an isocyanate mass percentage of 19.0%~22.0%. Then, the prepolymer, thermally conductive filler and thixotropic agent are added to the reactor and stirred evenly under vacuum to obtain component B.

[0042] (3) When using, mix component A and component B at a weight ratio of 100:(90~110) and let it stand at room temperature for seven days to achieve the desired performance.

[0043] This invention overcomes the technical difficulty of poor toughness when introducing diamine chain extenders into existing systems. By modifying diamine chain extenders into small molecule amine ethers, the reactivity is reduced and the operating time is extended, thereby improving the toughness and elongation of the product even with a large amount of filler added.

[0044] This invention improves the formulation of component B. In the conventional production of component B, inhibitors are usually added to prevent excessively rapid reactions or irregular chain segment arrangement. Commonly used inhibitors are phosphoric acid or acyl chloride. The addition of these inhibitors affects the hydrolysis resistance of the product. Although they can meet the requirements for use in most environments, prolonged use under high temperature and high humidity conditions will lead to a significant decrease in the product's performance retention rate, which is a drawback. This invention uses a novel adjuvant to replace the conventional inhibitors in component B. This adjuvant acts as an inhibitor in the system while improving the hydrolysis resistance of the product.

[0045] Compared with the prior art, the beneficial effects of the present invention are:

[0046] 1. This invention improves the high-temperature resistance of the product by adding amine ether polyols, while ensuring the bonding strength and toughness; at the same time, the addition of a novel inhibitor to component B can significantly extend the product's hydrolysis resistance retention rate.

[0047] 2. The thermally conductive polyurethane structural adhesive of the present invention can be operated at room temperature with sufficient operating time. While ensuring excellent high temperature resistance and hydrolysis resistance, it also maintains good toughness and high tensile strength.

[0048] 3. The preparation method of the present invention is simple and reasonable, the raw materials are readily available, and it is convenient for industrial production. Detailed Implementation

[0049] The present invention will be further described below with reference to the embodiments. Unless otherwise specified, the raw materials used in the embodiments are all commercially available conventional raw materials; unless otherwise specified, the process methods used in the embodiments are all conventional methods in the art.

[0050] The following is a description of some of the raw materials used in the examples:

[0051] DV125: Polyether polyol, number average molecular weight 375, functionality 3, Shandong Lanxing Dongda Co., Ltd.

[0052] E403: Amine ether polyol, number average molecular weight 300, functionality 4, Shandong Yinuowei Polyurethane Co., Ltd.

[0053] The preparation method of E403 is as follows: Diethyltoluene diamine is added to a reaction vessel, and after N2 replacement, stirring is started and the temperature is raised to 90°C. 15% of the total amount of propylene oxide is added to the reaction vessel to start the reaction. When the pressure in the vessel drops from 0.3~0.4 MPa to 0.15 MPa, heating is stopped, and cooling water is circulated to prevent overheating. The remaining propylene oxide is added to the reaction vessel, and the temperature is controlled not to exceed 110°C. The reaction is carried out at 95~105°C. When the pressure in the vessel drops to about zero, the reaction vessel is cooled down. After cooling to room temperature, a sample is taken for analysis. If it is qualified, the material is discharged. The molar ratio of diethyltoluene diamine to propylene oxide is 1:2.1.

[0054] R403: Polyether polyol, number average molecular weight 300, functionality 4, Shandong Lanxing Dongda Co., Ltd.

[0055] BMY: Castor oil, number-average molecular weight 690, functionality 2, Weifang Huanyu Oil Co., Ltd.

[0056] DL2000: Number average molecular weight 2000, functionality 2, Shandong Yinuowei New Materials Co., Ltd.

[0057] JAZ-058: Thermally conductive filler, Guangdong Jingge New Material Co., Ltd.;

[0058] XH-202: Thixotropic agent, hydrophobic fumed silica, Evonik Specialty Chemicals (Shanghai) Co., Ltd.;

[0059] KH560: Silane coupling agent, γ-glycidoxypropyltrimethoxysilane, Eastman Technologies Inc.

[0060] XS-3A: Water absorbent, 3A molecular sieve, Dalian Haixin Chemical Co., Ltd.;

[0061] TI: Dehydrating agent, p-toluenesulfonyl isocyanate, Tianjin Zhongxin Kaitai Chemical Co., Ltd.;

[0062] T-12: Catalyst, dibutyltin dilaurate, Evonik Specialty Chemicals (Shanghai) Co., Ltd.;

[0063] CB-18: Catalyst, bismuth neodecanoate, Taixing Shenglin Co., Ltd.;

[0064] HMDI: Dicyclohexylmethane diisocyanate, number average molecular weight 262, Bayer AG, Germany;

[0065] CD-C: Carbodiimide-modified isocyanate, number average molecular weight 300, Covestro Polymers China Ltd.;

[0066] MDI-100: Diphenylmethane diisocyanate, number average molecular weight 250, Yantai Wanhua Chemical Group Co., Ltd.

[0067] E100: Chain extender, dihexyltoluenediamine, Guangdong Shantou Hailiang New Materials Co., Ltd.;

[0068] PE-1000IS: Number average molecular weight 1000, functionality 2, polyester polyol, Shandong Yinuowei Polyurethane Co., Ltd.

[0069] PE-2000IS: Number average molecular weight 2000, functionality 2, polyester polyol, Shandong Yinuowei Polyurethane Co., Ltd.

[0070] PE-5504: Number average molecular weight 500, functionality 2, polyester polyol, Shandong Yinuowei Polyurethane Co., Ltd.

[0071] PE-230B: Number average molecular weight 573, functionality 2.3, bio-based polyol, Shandong Yinuowei Polyurethane Co., Ltd.;

[0072] ZX: Inhibitor, Phosphoric acid, Tianjin Fuyu Fine Chemical Co., Ltd.;

[0073] 65012: Inhibitor, N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, Beijing Jiyi Holding Group Co., Ltd.

[0074] Example 1

[0075] (1) Preparation of component A:

[0076] The total weight of component A is 100 parts by weight. First, add 2.5 parts of DV125, 3.8 parts of E403, 19.1 parts of BMY, 70.0 parts of JAZ-058, and 0.5 parts of KH560 to the reactor. Heat to 100°C and dehydrate under vacuum for 1 hour until the moisture content is less than 0.5‰. Cool to room temperature and then add 0.5 parts of XH-202, 3.5 parts of XS-3A, and 0.1 parts of T12. Stir under vacuum for 1 hour to obtain component A.

[0077] (2) Preparation of component B:

[0078] The total weight of component B is 100 parts by weight. First, 9.5 parts of PE-2000IS, 0.2 parts of 65012, and 19.0 parts of HMDI are added to a reactor, heated to 95°C and kept at that temperature for 3 hours. After cooling to room temperature, 0.2 parts of TI are added, and the mixture is packed into a container to obtain a prepolymer with an isocyanate content of 20.0% for later use. Then, 28.9 parts of the above prepolymer, 70.6 parts of JAZ-058, and 0.5 parts of XH-202 are added to the reactor, and the mixture is stirred evenly under vacuum to obtain component B.

[0079] (3) When using, mix component A and component B at a weight ratio of 100:100 and let it stand at room temperature for seven days to achieve the desired performance.

[0080] Example 2

[0081] (1) Preparation of component A:

[0082] The total weight of component A is 100 parts by weight. First, add 3.8 parts of DV125, 2.5 parts of E403, 19.1 parts of BMY, 70.0 parts of JAZ-058, and 0.5 parts of KH560 to the reactor. Heat to 100℃ and dehydrate under vacuum for 2 hours until the moisture content is less than 0.5‰. Cool to room temperature, then add 0.6 parts of XH-202, 3.3 parts of XS-3A, and 0.2 parts of T12. Stir under vacuum for 1.5 hours to obtain component A.

[0083] (2) Preparation of component B:

[0084] The total weight of component B is 100 parts by weight. First, 7.6 parts of PE-1000IS, 0.2 parts of 65012, and 20.9 parts of HMDI are added to a reactor, heated to 90°C and kept at that temperature for 5 hours. After cooling to room temperature, 0.2 parts of TI are added, and the mixture is packed into a container to obtain a prepolymer with an isocyanate content of 21.2% for later use. Then, 28.9 parts of the above prepolymer, 70.4 parts of JAZ-058, and 0.7 parts of XH-202 are added to the reactor, and the mixture is stirred evenly under vacuum to obtain component B.

[0085] (3) When using, mix components A and B at a weight ratio of 100:90 and let it stand at room temperature for seven days to achieve the desired performance.

[0086] Example 3

[0087] (1) Preparation of component A:

[0088] The total weight of component A is 100 parts by weight. First, add 5.1 parts of E403, 20.4 parts of BMY, 70.0 parts of JAZ-058 and 0.5 parts of KH560 to the reactor, heat to 100℃ and dehydrate under vacuum for 1 hour until the moisture content is less than 0.5‰, cool to room temperature, and then add 0.5 parts of XH-202, 3.4 parts of XS-3A and 0.1 parts of T12. Stir under vacuum for 2 hours to obtain component A.

[0089] (2) Preparation of component B:

[0090] The total weight of component B is 100 parts by weight. First, 9.5 parts of PE-2000IS, 0.2 parts of 65012, and 19.0 parts of HMDI are added to a reactor, heated to 92°C and kept at that temperature for 3 hours. After cooling to room temperature, 0.2 parts of TI are added, and the mixture is packed into a container to obtain a prepolymer with an isocyanate content of 20.0% for later use. Then, 28.9 parts of the above prepolymer, 70.3 parts of JAZ-058, and 0.8 parts of XH-202 are added to the reactor, and the mixture is stirred evenly under vacuum to obtain component B.

[0091] (3) When using, mix components A and B at a weight ratio of 100:110 and let it stand at room temperature for seven days to achieve the desired performance.

[0092] Example 4

[0093] (1) Preparation of component A:

[0094] The total weight of component A is 100 parts by weight. First, add 3.8 parts of DV125, 2.5 parts of E403, 19.1 parts of BMY, 70.0 parts of JAZ-058, and 0.5 parts of KH560 to the reactor. Heat to 100°C and dehydrate under vacuum for 1 hour until the moisture content is less than 0.5‰. Cool to room temperature and then add 0.6 parts of XH-202, 3.3 parts of XS-3A, and 0.2 parts of T12. Stir under vacuum for 1.5 hours to obtain component A.

[0095] (2) Preparation of component B:

[0096] The total weight of component B is 100 parts by weight. First, 8.5 parts of PE-2000IS, 0.2 parts of 65012, and 20.0 parts of HMDI are added to a reactor, heated to 90°C and kept at that temperature for 4 hours. After cooling to room temperature, 0.2 parts of TI are added, and the mixture is packed into a container to obtain a prepolymer with an isocyanate content of 21.2% for later use. Then, 28.9 parts of the above prepolymer, 70.5 parts of JAZ-058, and 0.6 parts of XH-202 are added to the reactor, and the mixture is stirred evenly under vacuum to obtain component B.

[0097] (3) When using, mix component A and component B at a weight ratio of 100:100 and let it stand at room temperature for seven days to achieve the desired performance.

[0098] Comparative Example 1

[0099] (1) Preparation of component A:

[0100] The total weight of component A is 100 parts by weight. First, add 3.8 parts of DV125, 2.5 parts of E403, 19.1 parts of BMY, 70.0 parts of JAZ-058, and 0.5 parts of KH560 to the reactor. Heat to 100°C and dehydrate under vacuum for 1 hour until the moisture content is less than 0.5‰. Cool to room temperature, then add 0.6 parts of XH-202, 3.3 parts of XS-3A, and 0.2 parts of T12. Stir under vacuum until homogeneous to obtain component A.

[0101] (2) Preparation of component B:

[0102] The total weight of component B is 100 parts by weight. First, 8.5 parts of PE-2000IS, 0.01 parts of phosphoric acid, and 19.99 parts of HMDI are added to a reactor, heated to 90°C and kept at that temperature for 4 hours. After cooling to room temperature, 0.2 parts of TI are added, and the mixture is packed into a container to obtain a prepolymer with an isocyanate content of 21.2% for later use. Then, 28.7 parts of the above prepolymer, 70.7 parts of JAZ-058, and 0.6 parts of XH-202 are added to the reactor, and the mixture is stirred evenly under vacuum to obtain component B.

[0103] (3) When using, mix component A and component B at a weight ratio of 100:100 and let it stand at room temperature for seven days to achieve the desired performance.

[0104] Comparative Example 2

[0105] (1) Preparation of component A:

[0106] The total weight of component A is 100 parts by weight. First, add 3.8 parts of DV125, 2.5 parts of E403, 19.1 parts of BMY, 70.0 parts of JAZ-058, and 0.5 parts of KH560 to the reactor. Heat to 100°C and dehydrate under vacuum for 1 hour until the moisture content is less than 0.5‰. Cool to room temperature, then add 0.6 parts of XH-202, 3.3 parts of XS-3A, and 0.2 parts of T12. Stir under vacuum until homogeneous to obtain component A.

[0107] (2) Preparation of component B:

[0108] The total weight of component B is 100 parts by weight. First, 8.5 parts of DL2000, 0.01 parts of phosphoric acid, and 19.99 parts of HMDI are added to a reactor, heated to 90°C and kept at that temperature for 4 hours. After cooling to room temperature, 0.2 parts of TI are added, and the mixture is packed into a container to obtain a prepolymer with an isocyanate content of 21.2% for later use. Then, 28.7 parts of the above prepolymer, 70.7 parts of JAZ-058, and 0.6 parts of XH-202 are added to the reactor, and the mixture is stirred evenly under vacuum to obtain component B.

[0109] (3) When using, mix component A and component B at a weight ratio of 100:100 and let it stand at room temperature for seven days to achieve the desired performance.

[0110] Comparative Example 3

[0111] (1) Preparation of component A:

[0112] The total weight of component A is 100 parts by weight. First, add 1.2 parts of DV125, 2.4 parts of E100, 20.3 parts of PE-230B, 71.0 parts of JAZ-058, and 0.6 parts of KH560 to the reactor. Heat to 100℃ and dehydrate under vacuum for 2 hours until the moisture content is less than 0.5‰. Cool to room temperature, then add 0.8 parts of XH-202, 3.5 parts of XS-3A, and 0.2 parts of T12. Stir under vacuum until homogeneous to obtain component A.

[0113] (2) Preparation of component B:

[0114] The total weight of component B is 100 parts by weight. First, 5.6 parts of PE-2000IS, 2.4 parts of PE-5504, 0.01 parts of phosphoric acid, and 3.69 parts of MDI-100 are added to the reactor. The temperature is raised to 80°C and held for 2 hours. Then, 14.7 parts of HMDI are added, and the temperature is raised to 90°C-95°C and held for 3 hours. After cooling to room temperature, 0.2 parts of TI are added. The mixture is then packed into a container to obtain a prepolymer with an isocyanate content of 20.3% for later use. Next, 26.6 parts of the above prepolymer, 72 parts of JAZ-058, 0.8 parts of XH-202, and 0.6 parts of KH560 are added to the reactor and stirred under vacuum until homogeneous to obtain component B.

[0115] (3) When using, mix component A and component B at a weight ratio of 100:100 and let it stand at room temperature for seven days to achieve the desired performance.

[0116] Comparative Example 4

[0117] (1) Preparation of component A:

[0118] The total weight of component A is 100 parts by weight. First, add 3.5 parts of R403, 17.7 parts of BMY, 2.4 parts of DV125, 71.2 parts of JAZ-058, and 0.6 parts of KH560 to the reactor. Heat to 100°C and dehydrate under vacuum for 2 hours until the moisture content is less than 0.5‰. Then cool to room temperature and add 0.8 parts of XH-202, 3.5 parts of XS-3A, and 0.3 parts of CB-18. Stir under vacuum until homogeneous to obtain component A.

[0119] (2) Preparation of component B:

[0120] The total weight of component B is 100 parts by weight. First, 6.8 parts of PE-1000IS, 0.01 parts of phosphoric acid and 21.79 parts of CD-C are added to the reactor, heated to 80°C and kept at that temperature for 3 hours. After cooling, 0.2 parts of TI are added, and the mixture is packed into a barrel to obtain a prepolymer with an isocyanate content of 20.4% for later use. Then, 28.8 parts of the above prepolymer, 70 parts of JAZ-058, 0.6 parts of JAZ-058 XH-202, and 0.6 parts of KH560 are added to the reactor, and the mixture is stirred evenly under vacuum to obtain component B.

[0121] (3) When using, mix component A and component B at a weight ratio of 100:100 and let it stand at room temperature for seven days to achieve the desired performance.

[0122] Performance testing

[0123] The products prepared in Examples 1-4 and Comparative Examples 1-4 were subjected to performance tests. Hardness was tested according to standard GB / T531-1999; peel strength was tested according to standard GB / T2792-1998, with a strip width of 25 mm. The aluminum material was clamped onto a BLD2005 electronic peeling machine for testing, with a loading speed of 5 mm / s and a test temperature of 25℃; thermal conductivity was tested according to standard GB / T 10294-2008. The test results are shown in Table 1.

[0124] Table 1 Performance test results of Examples 1-4 and Comparative Examples 1-4

[0125]

[0126] As shown in Table 1, the elongation of the thermally conductive polyurethane structural adhesive was significantly improved after introducing the new amine ether while ensuring its high-temperature resistance. At the same time, the hydrolysis resistance was significantly improved after introducing the new inhibitor.

[0127] Compared with Comparative Example 1, Example 4 has the same basic properties, but the tensile strength after 21 days (70℃) of hydrolysis is 7.5 MPa and 5.2 MPa respectively, showing a large difference in hydrolysis resistance. This is mainly because phosphate inhibitors will reduce the hydrolysis resistance of the product to a certain extent. The novel inhibitor used in this invention, which replaces phosphate, has almost no effect on the hydrolysis resistance of the product.

[0128] Compared with Example 4, the aluminum-aluminum bonding performance of Comparative Example 2 is slightly worse. This is mainly because the B component used in Example 4 is a branched polyester polyol, which promotes bonding, while the B component used in Comparative Example 2 is a polyether polyol, which has slightly lower performance than the polyester polyol in Example 4.

[0129] Compared with Comparative Examples 3-4, Examples 1-4 generally have higher elongation and are superior to the Comparative Examples. This is mainly because the present invention uses a novel amine ether polyol, which, in an effective amount, achieves the purpose of improving the toughness of the product.

[0130] Compared with Comparative Examples 1-4, Examples 1-4 all showed better high-temperature hydrolysis resistance. This was mainly because one of the raw materials for the synthesis of the novel amine ether polyol was E100, which helps with high-temperature resistance. Increasing the amount of amine ether polyol while ensuring toughness further improves the high-temperature resistance. In contrast, Comparative Examples 1-2 showed a significant decrease in tensile strength after high-temperature hydrolysis, while Comparative Examples 3-4 showed a significant decrease in both tensile strength and toughness, all of which affected the product's service life.

[0131] Compared with Comparative Examples 3-4, Examples 1-4 showed a significant improvement in both operating time and elongation. This is because the amine ether polyols modified E100, resulting in reduced activity and increased toughness. In Comparative Examples 3-4, the modified MDI had high activity and a high temperature resistant system with many active groups, leading to a short operating time, which was not conducive to worker operation.

Claims

1. A high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive, characterized in that, It includes component A and component B in a weight ratio of 100:(90~110); Component A comprises the following raw materials in parts by weight: 5.0-6.5 parts of polyol, Castor oil 19.0~21.0 parts, 70.0~72.0 parts of thermally conductive filler. Thixotropic agent 0.1~1.0 parts, 0.5~1.0 parts of silane coupling agent, 0-5.0 parts of absorbent material Catalyst 0.1~0.3 parts; Component B contains the following parts by weight of raw materials: Isocyanate 17.0~21.0 parts, Polyester polyol 5.0~10.0 parts, Water-removing agent 0.1~0.3 parts, 70.0~72.0 parts of thermally conductive filler. Thixotropic agent 0.1~1.0 parts, Inhibitor 0.01~0.5 parts; The polyol is a mixture of polyether polyol and amine ether polyol; the polyether polyol has a functionality of 3 and a number-average molecular weight of 300-500; the amine ether polyol is prepared by reacting diethyltoluene diamine and propylene oxide, has a functionality of 4 and a number-average molecular weight of 300-500. The inhibitor is N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine.

2. The high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive according to claim 1, characterized in that, The amine ether polyol is prepared by reacting diethyltoluene diamine and propylene oxide in a molar ratio of 1:(2.1~2.3).

3. The high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive according to claim 1, characterized in that, The thermally conductive filler is one or more of alumina, aluminum hydroxide, and magnesium hydroxide.

4. The high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive according to claim 1, characterized in that, The thixotropic agent is hydrophobic fumed silica; the silane coupling agent is one or more of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane; the desiccant is 3A molecular sieve; and the dehydrating agent is p-toluenesulfonyl isocyanate.

5. The high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive according to claim 1, characterized in that, The catalyst is one or more of bismuth catalysts, zinc catalysts, and tin catalysts.

6. The high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive according to claim 1, characterized in that, The isocyanate is one or both of isoflurane diisocyanate and dicyclohexylmethane diisocyanate.

7. The high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive according to claim 1, characterized in that, The polyester polyol is one or both of PE-2000IS and PE-1000IS.

8. A method for preparing a high-temperature resistant and hydrolysis-resistant thermally conductive polyurethane structural adhesive according to any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Preparation of component A: Add the polyol, castor oil, thermally conductive filler, and silane coupling agent from component A into the reactor, heat to 100-110℃, dehydrate to less than 0.5‰, cool to room temperature, and then add thixotropic agent, water absorbent, and catalyst. Stir for 1-2 hours to obtain component A. (2) Preparation of component B: First, the polyester polyol, isocyanate and inhibitor are mixed and heated to 90~95℃ and kept at that temperature for 3~5 hours. After cooling to room temperature, a dehydrating agent is added to obtain a prepolymer with an isocyanate mass percentage of 19.0%~22.0%. Then, the prepolymer, thermally conductive filler and thixotropic agent are added to the reactor and stirred evenly under vacuum to obtain component B. (3) When using, mix component A and component B at a weight ratio of 100:(90~110) and let it stand at room temperature for seven days to achieve the desired performance.

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