A thermally conductive potting compound that prevents sedimentation and its preparation method

Abstract

This invention relates to the field of potting compound technology and discloses a non-precipitating thermally conductive potting compound and its preparation method. The thermally conductive potting compound comprises component A: 100 parts by weight of vinyl silicone oil, 20-120 parts by weight of organosilicon-modified silicon carbide, and 9-13 parts by weight of hydrogen-containing silicone oil; and component B: 100 parts by weight of vinyl silicone oil and 0.0006-0.001 parts by weight of catalyst. The polymer molecular chains grafted onto the surface of the organosilicon-modified silicon carbide contain siloxane structural units, which have good interfacial compatibility with vinyl silicone oil. This allows for the formation of continuous thermally conductive pathways within the uniformly dispersed silicon carbide potting compound matrix, significantly improving the thermal conductivity and thermal performance of the potting compound. Simultaneously, the grafted polymer molecular chains contain alkenyl groups, which can undergo a curing reaction with vinyl silicone oil and hydrogen-containing silicone oil, providing excellent reinforcement and improving the tensile strength and elongation at break of the potting compound.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of pouring sealant, in particular to a heat-conducting pouring sealant capable of preventing precipitation and a preparation method thereof. BACKGROUND

[0002] Vinyl silicone oil is a polysiloxane polymer, and can be made into products such as silicone rubber and silicone pouring sealant. The silicone pouring sealant is widely used in electronic products, medical equipment, optical instruments and the like. The addition of a heat-conducting filler to the silicone pouring sealant can improve the heat-conducting performance of the pouring sealant and expand the practical application field thereof. Silicon carbide is an inorganic material with high thermal conductivity, high mechanical strength, high hardness and strong wear resistance, and has important applications in pouring sealants, conductive adhesives and coatings. The addition of silicon carbide to the silicone pouring sealant can improve the heat-conducting performance and mechanical strength and the like. However, the silicon carbide has poor compatibility with organic silicone polymer materials, poor dispersibility and is prone to precipitation, which affects the performance of the material. Patent CN114773857B discloses a binary composite silicone rubber material and a preparation method and application thereof. The binary composite silicone rubber material is obtained by mixing phenyl silicone rubber, vinyl silicone rubber raw rubber and coupling agent modified nano silicon carbide, and has good electrical conductivity and the like. However, the nano silicon carbide does not improve the heat-conducting performance and tensile strength of the silicone rubber material. SUMMARY

[0003] The application provides a heat-conducting pouring sealant capable of preventing precipitation, and solves the problem of easy precipitation of silicon carbide in the silicone pouring sealant, and improves the heat-conducting performance and mechanical performance of the pouring sealant.

[0004] Technical scheme: The heat-conducting pouring sealant capable of preventing precipitation comprises the following components in parts by weight: 100 parts of vinyl silicone oil, 20-120 parts of silicone-modified silicon carbide, 9-13 parts of hydrogen-containing silicone oil and 0.003-0.004 parts of an inhibitor alkynylcyclohexanol; and 100 parts of vinyl silicone oil and 0.0006-0.001 parts of a platinum catalyst.

[0005] The preparation method of the heat-conducting pouring sealant capable of preventing precipitation comprises the following steps: adding the vinyl silicone oil, the silicone-modified silicon carbide, the hydrogen-containing silicone oil and the inhibitor alkynylcyclohexanol into a stirrer, stirring and mixing to obtain component A; adding the vinyl silicone oil and the platinum catalyst into the stirrer, stirring and mixing to obtain component B; adding the component B into the component A and uniformly mixing to obtain the heat-conducting pouring sealant capable of preventing precipitation.

[0006] The preparation method of the organic silicon modified silicon carbide is that: KH550 modified silicon carbide is added into N,N-dimethylformamide, stirred and dispersed, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 5-(allyloxy)isophthaloyl chloride and triethylamine are added in a nitrogen atmosphere, and the reaction is carried out at 40-60 DEG C for 12-18 h, then filtered, washed with water and ethanol, and dried to obtain the organic silicon modified silicon carbide.

[0007]

[0008] Further, the amount of KH550 modified silicon carbide is 100 parts by weight, the amount of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane is 5-15 parts by weight, the amount of 5-(allyloxy)isophthaloyl chloride is 6-20 parts by weight, and the amount of triethylamine is 4.4-13 parts by weight.

[0009] Further, the preparation method of 5-(allyloxy)isophthaloyl chloride is that: 100 parts by weight of 5-(allyloxy)isophthalic acid is added into 600-800 parts by weight of thionyl chloride, and the reaction is carried out at 70-75 DEG C for 3-5 h, then the thionyl chloride is removed by vacuum concentration, and dried to obtain 5-(allyloxy)isophthaloyl chloride.

[0010]

[0011] Further, the preparation method of KH550 modified silicon carbide is that: silicon carbide powder is added into toluene, ultrasonic dispersion, KH550 is added, and the reaction is carried out in a nitrogen atmosphere, then filtered, washed and dried to obtain the KH550 modified silicon carbide.

[0012] The technical effect of the present application is that: the surface of the silicon carbide powder is modified by KH550 to introduce amino groups, then in-situ graft polymerization reaction is carried out with 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 5-(allyloxy)isophthaloyl chloride, so that the polymer molecular chain is grafted on the surface of the silicon carbide, and the organic silicon modified silicon carbide is obtained, finally, the vinyl silicone oil is used as the base glue, the hydrogen-containing silicone oil is used as the crosslinking agent, and the platinum catalyst is used as the curing agent, and the heat-conducting pouring sealant is obtained by blending.

[0013] The polymer molecular chain grafted on the surface of the organic silicon modified silicon carbide contains siloxane structural units, which has good interface compatibility with the vinyl silicone oil, so that the silicon carbide can be uniformly dispersed in the potting adhesive matrix to form a continuous heat conduction path, and the heat conduction coefficient and the heat conduction performance of the potting adhesive are significantly improved. Meanwhile, the grafted polymer molecular chain contains an alkenyl group, which can react with the vinyl silicone oil and the hydrogen-containing silicone oil to further improve the interface bonding performance between the silicon carbide and the vinyl silicone oil, so that the silicon carbide can play a good reinforcing role. By adding a proper amount of modified silicon carbide, the tensile strength and elongation at break of the potting adhesive can be obviously improved. DETAILED DESCRIPTION

[0014] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in combination with specific examples.

[0015] The vinyl silicone oil of the embodiment of the present application is model Vi-200K, Shanghai Yezhuang New Material Technology Co., Ltd. The hydrogen-containing silicone oil is model 202, Shenzhen Jipeng Silicon Fluorine Material Co., Ltd. The silicon carbide powder has an average particle size of 50 nm, Hebei Guangtuo Welding Material Co., Ltd. The platinum catalyst is Karstedt catalyst, Shanghai Fuli Hydrogen New Energy Technology Co., Ltd.

[0016] 5-(Allyloxy)isophthalic acid has a CAS number of 88194-15-4. 1,3-Bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane has a CAS number of 2469-55-8.

[0017] Example 1:

[0018] (1) 50 g of silicon carbide powder was added to 400 mL of toluene and ultrasonically dispersed, 1.2 g of KH550 was added, and the mixture was stirred at 90°C for 6 h in a nitrogen atmosphere. After filtration, the product was washed with water and ethanol and dried to obtain KH550 modified silicon carbide.

[0019] (2) 20 g of 5-(allyloxy)isophthalic acid was added to 120 g of thionyl chloride, and the mixture was stirred at 70°C for 5 h. During the reaction, the mixture was refluxed and condensed. Thionyl chloride was removed by vacuum concentration, and the product was dried to obtain 5-(allyloxy)isophthaloyl chloride.

[0020] (3) 50 g of KH550 modified silicon carbide was added to 700 mL of N,N-dimethylformamide and stirred and dispersed. 4.2 g of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 5.3 g of 5-(allyloxy)isophthaloyl chloride and 3.3 g of triethylamine were added in a nitrogen atmosphere, and the mixture was stirred at 40°C for 18 h. After filtration, the product was washed with water and ethanol and dried to obtain organic silicon modified silicon carbide.

[0021] (4) Add 1 kg of vinyl silicone oil, 0.2 kg of organosilicon modified silicon carbide, 100 g of hydrogen-containing silicone oil, and 0.034 g of inhibitor alkynylcyclohexanol to the stirrer and stir to obtain component A; add 1 kg of vinyl silicone oil and 0.007 g of platinum catalyst to the stirrer and stir to obtain component B; add component B to component A and mix well to obtain a heat-conducting potting compound that prevents precipitation.

[0022] Example 2:

[0023] (1) Add 20g of 5-(allyloxy)isophthalic acid to 160g of thionyl chloride, stir the reaction at 75℃ for 3h, reflux the reaction, concentrate under reduced pressure to remove thionyl chloride, and dry to obtain 5-(allyloxy)isophthaloyl chloride.

[0024] (2) Add 50g of KH550 modified silicon carbide (prepared in the same way as in Example 1) to 800mL of N,N-dimethylformamide, stir and disperse, add 7.5g of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 10g of 5-(allyloxy)isophthaloyl chloride and 6.5g of triethylamine in a nitrogen atmosphere, stir and react at 50℃ for 18h, filter, wash with water and ethanol, and dry to obtain organosilicon modified silicon carbide.

[0025] (3) Add 1 kg of vinyl silicone oil, 0.5 kg of organosilicon modified silicon carbide, 130 g of hydrogen-containing silicone oil, and 0.04 g of inhibitor alkynylcyclohexanol to the stirrer and stir to obtain component A; add 1 kg of vinyl silicone oil and 0.01 g of platinum catalyst to the stirrer and stir to obtain component B; add component B to component A and mix well to obtain a heat-conducting potting compound that prevents precipitation.

[0026] Example 3:

[0027] (1) Add 50g of KH550 modified silicon carbide (prepared in the same way as in Example 1) to 600mL of N,N-dimethylformamide, stir and disperse, add 2.5g of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 3g of 5-(allyloxy)isophthaloyl chloride (prepared in the same way as in Example 1), and 2.2g of triethylamine in a nitrogen atmosphere, stir and react at 40℃ for 18h, filter, wash with water and ethanol, and dry to obtain organosilicon modified silicon carbide.

[0028] (2) Add 1 kg of vinyl silicone oil, 0.2 kg of organosilicon modified silicon carbide, 90 g of hydrogen-containing silicone oil, and 0.03 g of inhibitor alkynylcyclohexanol to the stirrer and stir to obtain component A; add 1 kg of vinyl silicone oil and 0.006 g of platinum catalyst to the stirrer and stir to obtain component B; add component B to component A and mix well to obtain a heat-conducting potting compound that prevents precipitation.

[0029] Example 4:

[0030] (1) Add 50g of KH550 modified silicon carbide (prepared in the same way as in Example 1) to 800mL of N,N-dimethylformamide, stir and disperse, add 5.7g of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 7.6g of 5-(allyloxy)isophthaloyl chloride (prepared in the same way as in Example 1), and 4.3g of triethylamine in a nitrogen atmosphere, stir and react at 60℃ for 12h, filter, wash with water and ethanol, and dry to obtain organosilicon modified silicon carbide.

[0031] (2) Add 1 kg of vinyl silicone oil, 1.2 kg of organosilicon modified silicon carbide, 120 g of hydrogen-containing silicone oil, and 0.04 g of inhibitor alkynylcyclohexanol to the stirrer and stir to obtain component A; add 1 kg of vinyl silicone oil and 0.008 g of platinum catalyst to the stirrer and stir to obtain component B; add component B to component A and mix well to obtain a heat-conducting potting compound that prevents precipitation.

[0032] Comparative Example 1:

[0033] (1) Add 1kg vinyl silicone oil, 100g hydrogen-containing silicone oil and 0.034g inhibitor alkynylcyclohexanol to a stirrer and stir to obtain component A; add 1kg vinyl silicone oil and 0.007g platinum catalyst to a stirrer and stir to obtain component B; add component B to component A and mix well to obtain a heat-conducting potting compound that prevents precipitation.

[0034] Comparative Example 2:

[0035] (4) Add 1 kg of vinyl silicone oil, 0.2 kg of silicon carbide micro powder, 100 g of hydrogen-containing silicone oil, and 0.034 g of inhibitor alkynylcyclohexanol to the stirrer and stir to obtain component A; add 1 kg of vinyl silicone oil and 0.007 g of platinum catalyst to the stirrer and stir to obtain component B; add component B to component A and mix well to obtain a heat-conducting potting compound that prevents precipitation.

[0036] Comparative Example 3:

[0037] (4) Add 1 kg of vinyl silicone oil, 0.2 kg of KH550 modified silicon carbide (prepared in the same way as in Example 1), 100 g of hydrogen-containing silicone oil, and 0.034 g of inhibitor alkynylcyclohexanol to the stirrer and stir to obtain component A; add 1 kg of vinyl silicone oil and 0.007 g of platinum catalyst to the stirrer and stir to obtain component B; add component B to component A and mix well to obtain a thermally conductive potting compound that prevents precipitation.

[0038] Comparative Example 4:

[0039] (1) Add 50g of KH550 modified silicon carbide (prepared from Example 1) to 700mL of N,N-dimethylformamide, stir and disperse, add 4.2g of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 5.3g of isophthaloyl chloride and 3.3g of triethylamine under a nitrogen atmosphere, stir and react at 40℃ for 18h, filter, wash with water and ethanol, and dry to obtain organosilicon modified silicon carbide.

[0040] (2) Add 1 kg of vinyl silicone oil, 0.2 kg of organosilicon modified silicon carbide, 100 g of hydrogen-containing silicone oil, and 0.034 g of inhibitor alkynylcyclohexanol to the stirrer and stir to obtain component A; add 1 kg of vinyl silicone oil and 0.007 g of platinum catalyst to the stirrer and stir to obtain component B; add component B to component A and mix well to obtain a heat-conducting potting compound that prevents precipitation.

[0041] Comparative Example 5:

[0042] (1) Add 50g of KH550 modified silicon carbide (prepared from Example 1) to 700mL of N,N-dimethylformamide, stir and disperse, add 4.2g of ethylenediamine, 5.3g of 5-(allyloxy)isophthaloyl chloride and 3.3g of triethylamine under a nitrogen atmosphere, stir and react at 40℃ for 18h, filter, wash with water and ethanol, and dry to obtain modified silicon carbide.

[0043] (2) Add 1 kg of vinyl silicone oil, 0.2 kg of modified silicon carbide, 100 g of hydrogen-containing silicone oil, and 0.034 g of inhibitor alkynylcyclohexanol to the stirrer and stir to obtain component A; add 1 kg of vinyl silicone oil and 0.007 g of platinum catalyst to the stirrer and stir to obtain component B; add component B to component A and mix well to obtain a heat-conducting potting compound that prevents precipitation.

[0044] Dispersibility test: Taking Example 1 as an example, 1 kg of vinyl silicone oil, 0.2 kg of organosilicon-modified silicon carbide, 100 g of hydrogen-containing silicone oil, and 0.034 g of the inhibitor alkynylcyclohexanol were added to a stirrer and mixed to obtain component A; 1 kg of vinyl silicone oil (without platinum catalyst) was added to a stirrer and mixed to obtain component B. Component B was added to component A and mixed thoroughly to obtain the potting compound. The dispersibility of the potting compound was observed after standing at 25°C for 48 h. No platinum catalyst was added in any of the examples and comparative examples.

[0045] Table 1. Dispersibility Test of Encapsulant

[0046]

[0047]

[0048] The potting compound (with a platinum catalyst) was vulcanized at 25°C for 24 hours to prepare test pieces. The thermal conductivity was tested according to the national standard GB / T11205-2009. The tensile properties were tested according to the national standard GB / T 528-2009.

[0049] Table 2 Performance Tests of Encapsulating Compounds

[0050]

[0051] As shown in Tables 1 and 2, the silicone potting compound of Comparative Example 1 did not contain silicon carbide micro powder, resulting in a very low thermal conductivity and poor thermal performance.

[0052] In Comparative Example 2, no silicon carbide micropowder was added to the silicone potting compound. Due to the poor compatibility between silicon carbide micropowder and vinyl silicone oil, it was poorly dispersed in the potting compound matrix, easily agglomerated, and formed a large amount of sediment. This resulted in a decrease in the tensile strength and elongation at break of the potting compound, affecting its mechanical properties. Furthermore, the silicon carbide micropowder was not uniformly dispersed in the potting compound matrix, and did not form a good continuous thermal conductivity path, resulting in a low thermal conductivity and poor thermal conductivity of the silicone potting compound.

[0053] Examples 1-4 incorporated organosilicon-modified silicon carbide. The polymer grafted onto the silicon carbide surface contains siloxane structural units, exhibiting excellent interfacial compatibility with vinyl silicone oil. This allows for the formation of continuous thermally conductive pathways within the uniformly dispersed silicon carbide potting compound matrix, significantly improving the thermal conductivity and thermal performance of the potting compound. Simultaneously, the polymer molecular chain contains alkenyl groups, enabling it to undergo curing reactions with vinyl silicone oil and hydrogen-containing silicone oil, further enhancing the interfacial bonding between silicon carbide and vinyl silicone oil. This allows the silicon carbide to provide excellent reinforcement, and the addition of an appropriate amount of modified silicon carbide can significantly improve the tensile strength and elongation at break of the potting compound.

[0054] Compared with Example 1, Comparative Example 3 added KH550 modified silicon carbide. After modification, the compatibility between silicon carbide and vinyl silicone oil improved, and the thermal conductivity, tensile strength and elongation at break were higher than those of Comparative Example 1. However, it does not contain siloxane structural units and alkenyl groups, and cannot undergo curing reaction with vinyl silicone oil and hydrogen-containing silicone oil. This results in lower interfacial bonding performance between silicon carbide and vinyl silicone oil, and poor reinforcing effect of silicon carbide. The tensile strength and elongation at break are lower than those of Example 1.

[0055] Comparative Example 4 involved in-situ polymerization of KH550-modified silicon carbide with 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and isophthaloyl chloride. The resulting organosilicon-modified silicon carbide lacked alkenyl groups and could not undergo curing reactions with vinyl silicone oil and hydrogen-containing silicone oil, resulting in poor reinforcing properties. Comparative Example 5 involved in-situ polymerization of KH550-modified silicon carbide with ethylenediamine and 5-(allyloxy)isophthaloyl chloride. The resulting modified silicon carbide lacked siloxane structural units and had low compatibility with vinyl silicone oil, leading to poor reinforcing properties. The tensile strength and elongation at break of both examples were significantly lower than those of Example 1.

[0056] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A non-settling, thermally conductive potting compound, characterized in that, The composition comprises A component: 100 parts by weight of vinyl silicone oil, 20-120 parts by weight of silicone modified silicon carbide, 9-13 parts by weight of hydrogen-containing silicone oil, 0.003-0.004 parts by weight of inhibitor; B component: 100 parts by weight of vinyl silicone oil, 0.0006-0.001 parts by weight of catalyst; The preparation method of the silicone modified silicon carbide comprises the following steps: adding KH550 modified silicon carbide into N,N-dimethylformamide, stirring and dispersing, adding 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 5-(allyloxy)isophthaloyl chloride and triethylamine into the mixture under nitrogen atmosphere, filtering after reaction, washing with water and ethanol, and drying to obtain the silicone modified silicon carbide.

2. The anti-settling, thermally conductive pour-in-place sealant of claim 1, wherein, The catalyst is platinum catalyst, and the inhibitor is alkynyl cyclohexanol.

3. The anti-settling, thermally conductive pour-in-place sealant of claim 1, wherein, The reaction is carried out at 40-60℃ for 12-18h.

4. The anti-settling, thermally conductive pour-in-place sealant of claim 1, wherein, The amount of the KH550 modified silicon carbide is 100 parts by weight, the amount of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane is 5-15 parts by weight, the amount of 5-(allyloxy)isophthaloyl chloride is 6-20 parts by weight, and the amount of triethylamine is 4.4-13 parts by weight.

5. The anti-settling, thermally conductive pour-in-place sealant of claim 4, wherein, The preparation method of the 5-(allyloxy)isophthaloyl chloride comprises the following steps: adding 5-(allyloxy)isophthalic acid into sulfuryl chloride, and removing sulfuryl chloride by vacuum concentration after reaction, and drying to obtain 5-(allyloxy)isophthaloyl chloride.

6. The anti-settling, thermally conductive pour-in-place sealant of claim 5, wherein, The amount of the sulfuryl chloride is 600-800 parts by weight, and the amount of 5-(allyloxy)isophthalic acid is 100 parts by weight.

7. The anti-settling, thermally conductive pour-in-place sealant of claim 5, wherein, The reaction is carried out at 70-75℃ for 3-5h.

8. The anti-settling, thermally conductive pour-in-place sealant of claim 4, wherein, The preparation method of the KH550 modified silicon carbide comprises the following steps: adding silicon carbide powder into toluene, ultrasonic dispersing, adding KH550, and reacting under nitrogen atmosphere, filtering, washing, and drying to obtain the KH550 modified silicon carbide.

9. A process for the preparation of a non-settling, thermally conductive pouring compound according to any one of claims 1 to 8, characterized in that The preparation method comprises the following steps: adding vinyl silicone oil, silicone modified silicon carbide, hydrogen-containing silicone oil and inhibitor into a stirrer, and stirring and mixing to obtain the A component; The preparation method comprises the following steps: adding vinyl silicone oil and catalyst into a stirrer, stirring and mixing to obtain the B component, adding the B component into the A component, and mixing uniformly to obtain the anti-settling heat-conducting pouring sealant.

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