Two-component condensation type heat-conducting silicone sealant and preparation method thereof

Abstract

The present application relates to a kind of two-component condensation type heat-conducting silicone sealant, comprising the following mass parts of component: component A: alpha, omega-dihydroxy polydimethylsiloxane 0~90 parts, side chain contains epoxy group's end hydroxyl polydimethylsiloxane 10~100 parts, heat-conducting filler I 250~330 parts, deep curing accelerator 1~5 parts;Component B: alkoxyl-terminated polydimethylsiloxane 0~90 parts, amino group-containing alkoxyl-terminated polydimethylsiloxane 10~100 parts, heat-conducting filler II 250~330 parts, plasticizer 0~50 parts, coupling agent 0~20 parts, catalyst 0.05~0.5 parts, hydroxyl scavenger 1.0~5.0 parts.The present application realizes deep curing under closed condition and has good high temperature and high humidity resistance, simultaneously, has good storage stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of silicone sealant, and particularly relates to a two-component condensation type heat-conducting silicone sealant and a preparation method thereof. BACKGROUND

[0002] Heat-conducting sealant is widely used in the fields of electronic appliances, new energy, 5G, automobiles, etc. Heat-conducting sealant is classified into epoxy, acrylic, polyurethane, silicone, etc. according to the material category. Among them, silicone heat-conducting sealant has obvious advantages in insulation, temperature resistance, weather resistance and flexibility, and therefore is increasingly concerned by the market. Silicone sealant is classified into single-component and two-component according to the packaging form, and is classified into condensation type and addition type according to the reaction mechanism. Although single-component addition type silicone sealant can be rapidly cured by heating, the adhesion is generally far inferior to that of condensation type. The curing of single-component condensation type silicone sealant requires additional moisture, and deep curing cannot be achieved in the absence of moisture. Even if moisture is not isolated, it is difficult to achieve a curing depth of more than 10 mm, and the curing speed is relatively slow. In the absence of moisture isolation, it generally takes at least 3 to 7 days to achieve a curing depth of 6 mm.

[0003] Two-component addition type silicone sealant generally requires heating for vulcanization, and the catalyst is sensitive and easily affected to cause uncuring. In addition, the adhesion of addition type silicone sealant is generally weak. Two-component condensation type silicone sealant can be rapidly cured at room temperature without additional moisture, and the catalyst is not easily affected by elements such as nitrogen, phosphorus and sulfur. However, the condensation reaction continuously proceeds in the positive direction during the curing process of two-component condensation type sealant, so the curing degree is often affected in a closed condition. In a serious case, the sealant does not even cure in a closed condition. In addition, the curing agent component of two-component condensation type silicone sealant generally has poor storage stability, and it is generally difficult to achieve a shelf life of more than 6 months. After 6 months, the curing speed is slow, the hardness is reduced, and the adhesive strength is significantly reduced. In order to improve the curing degree in a closed condition, the content of hydroxyl groups or water in the A component is generally increased. However, if water is added alone in the A component, delamination may occur during storage due to the incomplete compatibility of water with the system, and the curing is non-uniform due to the large difference in water content in different parts. In order to improve the storage stability of the B component, additional alkoxysilane or hydroxyl scavenger is generally added, which can extend the shelf life of the B component to a certain extent. However, on the other hand, it will affect the curing degree of the system in a closed environment, because excessive alkoxyl or hydroxyl scavenger will preferentially react with hydroxyl groups when the A and B components are mixed, and thus the crosslinking network is not complete, resulting in low mechanical properties such as hardness and strength. That is, it is generally difficult to simultaneously consider complete moisture isolation and curing and the storage stability of the B component in the prior art.

[0004] CN110240888A discloses a two-component condensation type heat-conducting silicone gel and a preparation method thereof, comprising the following components by weight fraction: component A: alpha, omega-dihydroxy polydimethylsiloxane 35-60 parts; silicon powder 40-60 parts; zinc-containing compound 0.5-5 parts; catalyst 0.03-0.1 parts; component B: alkoxyl-terminated polydimethylsiloxane 30-55 parts; silicon powder 40-60 parts; crosslinking agent 2-10 parts; coupling agent 1-5 parts. The application uses a zinc-containing compound in the formula to achieve deep curing of the silicone gel, but does not involve improvement of storage stability, and the thermal conductivity is relatively low, less than 0.8 W / (m·K).

[0005] CN104293231 B discloses a dealcoholization type sealant with long storage stability and a preparation method thereof, wherein a self-made hydroxyl scavenger is used in the preparation process, which is prepared from an amino silane coupling agent and a diisocyanate compound. The hydroxyl scavenger has the dual functions of removing hydroxyl groups and increasing adhesion, and when applied in silicone sealant, it has a storage stability period of at least 12 months and excellent adhesion to various substrates, especially to solar photovoltaic modules, aluminum frame, back plate and junction box. However, the application does not involve the high temperature and high humidity resistance of the silicone sealant. SUMMARY

[0006] In view of the above problems existing in the prior art, the application provides a two-component condensation type heat-conducting silicone sealant and a preparation method thereof, which can be deep-cured in a closed state and has good storage stability, and also has good high temperature and high humidity resistance and high thermal conductivity.

[0007] The application achieves the above-mentioned purposes through the following technical solutions:

[0008] A two-component condensation type heat-conducting silicone sealant, comprising the following components by mass fraction:

[0009] Component A:

[0010]

[0011] The total fraction of the alpha, omega-dihydroxy polydimethylsiloxane and the side chain epoxy group-containing end hydroxyl polydimethylsiloxane is 100 parts;

[0012] Component B:

[0013]

[0014] The total fraction of the alkoxyl-terminated polydimethylsiloxane, the end amino group-containing alkoxyl-terminated polydimethylsiloxane and the plasticizer is 100 parts;

[0015] The mass ratio of the A component and the B component is 1:(0.5-1.2).

[0016] In the present application, the side chain epoxy-containing end hydroxyl polydimethylsiloxane in the A component and the end amino-containing alkoxyl-terminated polydimethylsiloxane in the B component can react in the absence of moisture, thereby making up for the defect that the glue cannot be deeply cured in a sealed state, and also bringing about the improvement of the glue bulk strength and bonding strength, and the significant improvement of the high temperature and high humidity resistance. In addition, the deep curing accelerator further promotes the deep curing of the glue layer in the case of moisture isolation. The present application finally obtains the two-component heat-conducting organic silicone sealant with storage stability, deep curing in a sealed state, high bonding strength and excellent high temperature and high humidity resistance by introducing the side chain epoxy-containing end hydroxyl polydimethylsiloxane and the end amino-containing alkoxyl-terminated polydimethylsiloxane, and the specific ratio of the above raw materials.

[0017] Further, the side chain epoxy-containing end hydroxyl polydimethylsiloxane in the A component has the following structural formula:

[0018]

[0019] wherein m is an integer of 10-5000, n is an integer of 1-500, and 100

[0020] R1 is methyl, ethyl or epoxypropoxypropyl;

[0021] R2 and R3 are independently methyl or ethyl.

[0022] The side chain epoxy-containing end hydroxyl polydimethylsiloxane in the A component can be prepared by the following method:

[0023] Octamethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetrakis(propyl glycidyl ether) cyclotetrasiloxane and water are subjected to ring-opening copolymerization reaction under the action of a catalyst, and low-boiling substances are removed by high-temperature and reduced-pressure after the reaction is completed.

[0024] The reaction formula is shown as follows:

[0025]

[0026] Preferably, the amount of 2,4,6,8-tetramethyl-2,4,6,8-tetra(propyl glycidyl ether) cyclotetrasiloxane is 2-8 wt% of octamethylcyclotetrasiloxane, more preferably 3-6 wt%; the amount of water is 0.005%-0.3% of the total mass of octamethylcyclotetrasiloxane and 2,4,6,8-tetramethyl-2,4,6,8-tetra(propyl glycidyl ether) cyclotetrasiloxane, more preferably 0.05%-0.15%. Water is a capping agent, and its amount affects the values of the polymerization degrees m and n; the greater the amount of water, the smaller the polymerization degree, and vice versa. The catalyst is tetramethylammonium hydroxide, and its amount is 0.01%-0.05% of the total mass of octamethylcyclotetrasiloxane and 2,4,6,8-tetramethyl-2,4,6,8-tetra(propyl glycidyl ether) cyclotetrasiloxane.

[0027] Preferably, the conditions of the ring-opening copolymerization are 80-110°C for 4-8 h; and the conditions of the high-temperature and reduced-pressure removal are vacuuming to -0.09 MPa or lower and heating to 150-160°C for 3-8 h to remove low-boiling substances. The catalyst is decomposed into low-boiling substances under high-temperature conditions and removed under reduced pressure.

[0028] Further, the viscosity of the α,ω-dihydroxypolydimethylsiloxane in the A component is 400-10,000 cps at 25°C, preferably 700-3,000 cps, which can be adjusted to the desired viscosity by compounding different viscosity α,ω-dihydroxypolydimethylsiloxanes; the amount of D3-D10 residual mixed cyclic bodies in the α,ω-dihydroxypolydimethylsiloxane is less than 0.1 wt%; and the amount of the α,ω-dihydroxypolydimethylsiloxane in the A component is preferably 40-80 parts, which can be 40 parts, 50 parts, 60 parts, 70 parts, or 80 parts.

[0029] Further, the deep curing accelerator in the A component is compounded from white carbon black, water, and an emulsifier in a mass ratio of 100:(5-50):(0.5-5); and the emulsifier is at least one of glycerol monostearate, soybean phospholipid, sodium dodecyl sulfate, fatty acid soap, polyoxyethylene ether, polyoxypropylene ether, and polyether silicone oil, preferably polyether silicone oil. The deep curing accelerator can provide sufficient silicon hydroxyl groups and free water to promote deep curing of the product in complete isolation from moisture, but white carbon black and water have poor compatibility when directly added, and water is prone to precipitation. The present application significantly increases the compatibility of white carbon black, water, and the system by compounding with an emulsifier. In addition, the amount of the deep curing accelerator cannot be excessive, as excessive amounts can cause the curing speed to slow down and the product to become sticky.

[0030] Further, the structure of the amino-terminated alkoxyl-terminated polydimethylsiloxane in the B component is as follows:

[0031]

[0032] Where m1 is an integer between 50 and 5000;

[0033] R5 and R6 are independently methoxy, ethoxy, or propoxy;

[0034] R7 is aminopropyl, aminoethylaminopropyl, diethylaminopropyl, diethylaminomethyl, n-butylaminopropyl, or n-butylaminomethyl.

[0035] The amino-terminated alkoxy-terminated polydimethylsiloxane in component B can be prepared by the following method:

[0036] α,ω-dihydroxypolydimethylsiloxane and aminoalkoxysilane undergo a condensation reaction under the action of a catalyst, and low-boiling substances are removed under reduced pressure after the reaction is completed.

[0037] Preferably, the aminoalkoxysilane is at least one selected from N-aminoethyl-3-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, diethylaminomethyltriethoxysilane, and n-butylaminomethyltriethoxysilane, and its amount is 5-8 wt% of α,ω-dihydroxypolydimethylsiloxane; the catalyst is butanone oxime, and its amount is 0.5-1 wt% of α,ω-dihydroxypolydimethylsiloxane; the reaction conditions are 80-100°C for 6-8 h; the conditions for removing low-boiling substances under reduced pressure are: removing low-boiling substances by heating to 120-130°C under a vacuum of -0.09 MPa for 1-2 h.

[0038] Furthermore, the alkoxy-terminated polydimethylsiloxane in component B is at least one selected from dimethoxy-terminated polydimethylsiloxane, trimethoxy-terminated polydimethylsiloxane, diethoxy-terminated polydimethylsiloxane, triethoxy-terminated polydimethylsiloxane, trimethoxysilylethyl-terminated polydimethylsiloxane, and triethoxysilylethyl-terminated polydimethylsiloxane. The alkoxy-terminated polydimethylsiloxane in component B can be prepared in-house or commercially available.

[0039] Furthermore, the viscosity of the alkoxy-terminated polydimethylsiloxane in component B at 25°C is 400–10000 cps, preferably 700–5000 cps, and can be adjusted to the desired viscosity by compounding alkoxy-terminated polydimethylsiloxanes of different viscosities; the mass fraction of the alkoxy-terminated polydimethylsiloxane is preferably 30–50 parts, specifically 30 parts, 40 parts, or 50 parts.

[0040] Furthermore, each of the thermally conductive fillers I and II independently comprises at least one of aluminum hydroxide, alumina, quartz powder, zinc oxide, aluminum nitride, boron nitride, magnesium oxide, zinc borate, expanded graphite, nitrogen-phosphorus flame retardant, phosphorus-silicon flame retardant, and platinum complex; its particle size is 0.5–20 μm, preferably with a particle size distribution of 50–60 wt% for particles with a diameter of 0.5–5 μm and 40–50 wt% for particles with a diameter of 10–20 μm. Smaller particle size thermally conductive fillers provide better anti-settling effects, while larger particle size thermally conductive fillers are more conducive to improving thermal conductivity. The above-mentioned particle size distribution can achieve better overall performance.

[0041] Preferably, the thermally conductive filler I and thermally conductive filler II undergo surface hydrophobic treatment, and the hydrophobic treatment agent is an aminosilane coupling agent, such as KH550, KH540, KH792 or KH602; the amount of aminosilane coupling agent is 0.1wt% to 1wt% of the thermally conductive filler.

[0042] Furthermore, the plasticizer described in component B is polydimethylsiloxane, with a viscosity of 50–500 cps at 25°C; and / or

[0043] The coupling agent is at least one of aminosilane coupling agents, bisaminosilane coupling agents, bisaminosilane coupling agent oligomers, and 1,3,5-tris(trimethoxysilylpropyl)polyisocyanate, for example, at least one of JH-AP1231, KH-550, and KH-792; and / or

[0044] The catalyst is at least one of dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dimethyl dinedecanoate, and chelated organotin.

[0045] Furthermore, the hydroxyl scavenger in component B is an anhydride derivative, such as at least one of 2-methoxyacetic anhydride, 2-ethoxyacetic anhydride, 4-methoxyphenylacetic anhydride, and phenoxyacetic anhydride. During storage, hydroxyl groups or water within or outside the system can cause premature hydrolysis of the coupling agent and polymer terminal alkoxy groups in component B, leading to a rearrangement reaction under the action of a catalyst. The resulting product has low curing activity, affecting the curing and adhesive properties of the product during use, i.e., affecting the storage stability of component B. The dosage of the hydroxyl scavenger must be controlled within an appropriate range. Too low a dosage has little effect on improving the storage stability of component B; too high a dosage will react with the polysiloxane in component A, thus affecting the crosslinking and curing of the entire system. Therefore, the dosage of the hydroxyl scavenger must be within the aforementioned range. Compared to conventional silazane-based hydroxyl scavengers, the use of anhydride-based hydroxyl scavengers does not significantly reduce the adhesive strength of the adhesive system and does not produce unpleasant odors during the reaction. Therefore, its dosage range can be wider, i.e., the dosage is easier to control.

[0046] The placement of each functional reagent in this invention is crucial. For example, the catalyst and coupling agent can only be in component B. If they are placed in component A, the viscosity of component A will increase during storage, affecting its usability. Aqueous component A, under the catalytic action of the catalyst, causes dihydroxypolydimethylsiloxane to degrade slowly, thus slowing down the product's curing speed. Aqueous component A also causes the coupling agent to hydrolyze and crosslink, affecting the product's deep curing.

[0047] Preferably, in this invention, the mass ratio of component A to component B is 1:(0.8 to 1.2).

[0048] This invention also provides a method for preparing the above-mentioned two-component condensation-type thermally conductive silicone sealant, comprising the following steps:

[0049] (S1) Preparation of component A: α,ω-dihydroxy polydimethylsiloxane, hydroxyl-terminated polydimethylsiloxane with epoxy groups on the side chain, thermally conductive filler I, and deep curing accelerator are added to a mixing tank, stirred and mixed, and vacuum degassed. Then, the mixture is dispensed and stored in a moisture-free environment to obtain component A.

[0050] (S2) Preparation of component B: Alkoxy-terminated polydimethylsiloxane, amino-terminated alkoxy-terminated polydimethylsiloxane, thermally conductive filler II, and plasticizer are added to a stirred tank, stirred and mixed, and vacuum dehydrated. After cooling to room temperature, coupling agent, catalyst and hydroxyl scavenger are added. Then, the mixture is stirred under vacuum at room temperature, dispensed, and stored in the absence of moisture to obtain component B.

[0051] Preferably, the stirring, mixing and vacuum degassing in step (S1) is performed by stirring at a speed of 200-500 r / min for 30-90 min, while maintaining a vacuum of -0.05 to -0.1 MPa.

[0052] Preferably, the stirring and vacuum dehydration in step (S2) is to stir at a speed of 200-500 r / min at 80-150°C for 30-90 min, while maintaining a vacuum degree of -0.05 to -0.1 MPa; the vacuum stirring is to stir at a vacuum degree of -0.05 to -0.1 MPa for 10-60 min.

[0053] The present invention also provides the above-mentioned condensation-type two-component thermally conductive silicone sealant for thermal management, sealing and bonding and thermally conductive bonding in the fields of electronics, 5G, new energy and automobiles, and is especially suitable for thermally conductive bonding related to new energy battery packs.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0055] (1) In this invention, a hydroxyl-terminated polydimethylsiloxane with epoxy groups on the side chain is introduced into component A, and an alkoxy-terminated polydimethylsiloxane with amino groups is introduced into component B. The amino and epoxy groups can react in the absence of moisture, which on the one hand compensates for the deep curing of the adhesive in a completely sealed state, and on the other hand can significantly improve the strength of the adhesive itself and the adhesive strength, and can even completely replace the coupling agent. In addition, since the epoxy groups preferentially react to remove the most active hydrogen on the amino group during the curing process, a steric hindrance effect is brought about, which greatly suppresses the negative effects of the presence of amino groups in the system that cause poor resistance to high temperature and high humidity, and ultimately the cured adhesive system still has good resistance to high temperature and high humidity.

[0056] (2) The present invention introduces an appropriate amount of deep curing accelerator into component A, thereby further promoting the deep curing of the product under conditions of complete moisture isolation.

[0057] (3) In a preferred embodiment of the present invention, an acid anhydride hydroxyl scavenger is introduced into component B. It has no significant negative effect on reducing the adhesive strength of the adhesive system, and the dosage range is wider, that is, the dosage is easier to control, and it can more effectively improve the storage stability of component B.

[0058] (4) The mixing ratio of component A and component B of the present invention is 1:(0.5 to 1.2), which has a higher tolerance for equipment glue application than products with a ratio of 10:1 or 6:1. Detailed Implementation

[0059] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0060] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; all parts are parts by weight; and all reagents and materials are commercially available unless otherwise specified.

[0061] The raw materials used in the preparation examples, embodiments, and comparative examples are as follows:

[0062] α,ω-dihydroxypolydimethylsiloxane:

[0063] Model Viscosity (cps) D3-D10 content Supplier HP48V750 750 ＜0.1％ Jiangxi Lansheng Starfire Silicone Co., Ltd. OP48V1500 1500 ＜0.03％ Jiangxi Lansheng Starfire Silicone Co., Ltd. HP48V5000 5000 ＜0.1％ Jiangxi Lansheng Starfire Silicone Co., Ltd.

[0064] Vinyl-terminated silicone oil:

[0065]

[0066]

[0067] Plasticizer polydimethylsiloxane: model H47V100, viscosity 100cps, selected from Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd.

[0068] Silane-modified polyether: Model AG-550, selected from Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd.

[0069] N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792): Industrial grade, selected from Jingzhou Jianghan Fine Chemical Co., Ltd.

[0070] Silica YX-200S, Fujian Yuanxiang New Materials Co., Ltd.

[0071] 2-Methoxyacetic anhydride, propionic anhydride, butanone oxime, trimethoxysilane, chloroplatinic acid hexahydrate, 2,4,6,8-tetramethyl-2,4,6,8-tetra(propylglycidyl ether)cyclotetrasiloxane, octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, and dibutyltin dilaurate are all selected from Aladdin.

[0072] Aluminum hydroxide (D50 = 3 μm) and aluminum oxide (D50 = 15 μm) were selected from Guangdong Jingge New Materials Co., Ltd.

[0073] Preparation Example a1---Preparation of hydroxyl-terminated polydimethylsiloxanes with epoxy groups in the side chain

[0074] 95 parts of octamethylcyclotetrasiloxane, 5 parts of 2,4,6,8-tetramethyl-2,4,6,8-tetra(propyl glycidyl ether)cyclotetrasiloxane, 0.06 parts of deionized water, and 0.03 parts of tetramethylammonium hydroxide were added to a reaction vessel equipped with a stirrer, heater, and vacuum device. The mixture was stirred continuously under nitrogen protection and heated to 90°C for 6 hours. The temperature was then raised to 160°C, and the vacuum was evacuated to -0.095 MPa while stirring continuously for 6 hours to remove low-boiling substances. The mixture was then cooled to room temperature to obtain a hydroxyl-terminated polydimethylsiloxane with epoxy groups on the side chain, labeled a1.

[0075] Preparation Example b1---Preparation of alkoxy-terminated polydimethylsiloxanes containing terminal amino groups

[0076] 100 parts of α,ω-dihydroxypolydimethylsiloxane OP48V1500, 6 parts of KH792 (N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane), and 0.5 parts of butanone oxime were added to a high-speed stirred tank equipped with a nitrogen system, a vacuum system, and a heating and cooling system. The mixture was continuously stirred and heated to 100°C under dry nitrogen protection for 8 hours. Then, the mixture was evacuated to -0.095 MPa at 120°C and stirred continuously for 1 hour to remove low-boiling substances. The mixture was then cooled to room temperature to obtain an amino-terminated alkoxy-terminated polydimethylsiloxane with a viscosity of 1980 cps (mPa·s), labeled as b1.

[0077] Preparation of alkoxyl-terminated polydimethylsiloxane

[0078] Preparation Example 1

[0079] 20 parts of α,ω-dihydroxypolydimethylsiloxane HP48V750, 30 parts of α,ω-dihydroxypolydimethylsiloxane OP48V1500, and 50 parts of α,ω-dihydroxypolydimethylsiloxane HP48V5000 were added to a high-speed stirred tank equipped with a nitrogen system, a vacuum system, and a heating and cooling system. Then, 3 parts of vinyltrimethoxysilane were added and mixed thoroughly. Next, 0.5 parts of butanone oxime were added. The mixture was then stirred continuously under nitrogen protection and gradually heated to 100°C for 24 hours. Finally, the low-boiling substances were removed under vacuum at 120°C and cooled to room temperature to obtain dimethoxy-terminated polydimethylsiloxane, labeled as polyX1.

[0080] Preparation Example 2

[0081] 50 parts of vinyl-terminated silicone oil L621V1000 and 50 parts of vinyl-terminated silicone oil L621V5000 were added to a high-speed stirred tank equipped with a nitrogen system, a vacuum system, and a heating and cooling system. Then, trimethoxysilane and chloroplatinic acid hexahydrate (20 ppm total amount) were added in an equimolar ratio to the vinyl-terminated silicone oil. The mixture was then reacted at 50°C for 24 h under nitrogen protection. Finally, the low-boiling substances were removed under vacuum at 120°C and cooled to room temperature to obtain trimethoxysilyl ethyl-terminated polydimethylsiloxane, labeled as X2.

[0082] Example 1

[0083]

[0084]

[0085] Prepare component A and component B according to the amounts of each raw material used in the table above:

[0086] (S1) Preparation of component A: α,ω-dihydroxypolydimethylsiloxane, thermally conductive filler I, and deep curing accelerator were added to a stirring tank and stirred at 400 r / min and vacuum degree -0.095 MPa for 60 min. Then the mixture was dispensed and stored in a moisture-free environment to obtain component A.

[0087] (S2) Preparation of component B: Alkoxy-terminated polydimethylsiloxane, thermally conductive filler II, and plasticizer were added to a stirred tank and vacuum dehydrated for 90 min at 400 r / min, vacuum degree -0.095 MPa, and temperature 100℃. After cooling to room temperature, coupling agent, catalyst, and hydroxyl scavenger were added, and the mixture was vacuum stirred for 20 min at room temperature. The mixture was then dispensed and stored in a moisture-free environment to obtain component B.

[0088] When using, mix component A and component B in a 1:1 mass ratio.

[0089] Example 2

[0090]

[0091]

[0092] Following the preparation method of Embodiment 1, and using the raw material ratios in this embodiment, components A and B are prepared. When used, components A and B are mixed at a mass ratio of 1:1.

[0093] Example 3

[0094]

[0095]

[0096] Following the preparation method of Embodiment 1, and using the raw material ratios in this embodiment, components A and B are prepared.

[0097] When using, mix component A and component B at a mass ratio of 1:1.

[0098] Example 4

[0099] The rest is the same as in Example 1, except that when using it, components A and B are mixed at a mass ratio of 1:0.5.

[0100] Example 5

[0101] The rest is the same as in Example 1, except that when using it, components A and B are mixed at a mass ratio of 1:1.2.

[0102] Example 6

[0103] The rest is the same as in Example 1, except that in component A, there are 0 parts of α,ω-dihydroxy polydimethylsiloxane HP48V750 and 100 parts of terminal hydroxyl polydimethylsiloxane with epoxy groups in the side chain.

[0104] Example 7

[0105] The rest is the same as in Example 1, except that 90 parts of α,ω-dihydroxy polydimethylsiloxane HP48V750 and 10 parts of terminal hydroxyl polydimethylsiloxane with epoxy groups in the side chain are in component A.

[0106] Example 8

[0107] The rest is the same as in Example 1, except that in component B, there are 0 parts of alkoxy-terminated polydimethylsiloxane, 100 parts of alkoxy-terminated polydimethylsiloxane containing amino groups, and 0 parts of plasticizer.

[0108] Example 9

[0109] The rest is the same as in Example 1, except that in component B, there are 90 parts of alkoxy-terminated polydimethylsiloxane, 10 parts of alkoxy-terminated polydimethylsiloxane containing amino groups, and 0 parts of plasticizer.

[0110] Example 10

[0111] The rest is the same as in Example 1, except that hexamethyldisilazane hydroxyl scavenger is used instead of 2-methoxyacetic anhydride in component B.

[0112] Comparative Example 1

[0113] The rest is the same as in Example 1, except that component B, α,ω-dimethoxy-terminated polydimethylsiloxane, is 70 parts, and alkoxy-terminated polydimethylsiloxane b1 containing amino groups is 0 parts.

[0114] Comparative Example 2

[0115] The rest is the same as in Example 1, except that 100 parts of α,ω-dihydroxy polydimethylsiloxane HP48V750 are in component A, and 0 parts of terminal hydroxyl polydimethylsiloxane a1 with epoxy groups in the side chain are in component A.

[0116] Comparative Example 3

[0117] The rest is the same as in Example 1, except that in component A, 95 parts of α,ω-dihydroxy polydimethylsiloxane HP48V750 and 5 parts of terminal hydroxyl polydimethylsiloxane a1 with epoxy groups in the side chain are used; in component B, 65 parts of α,ω-dimethoxy-terminated polydimethylsiloxane and 5 parts of alkoxy-terminated polydimethylsiloxane b1 with amino groups are used.

[0118] Results and Analysis

[0119] The silicone sealants prepared in the above examples and comparative examples were subjected to the following performance tests, and the results are shown in Table 1.

[0120] Open-cure hardness: After mixing components AB evenly in proportion, cure in an environment of 23±2℃ and 50±5%RH for 72h, and then test according to GB / T 531.

[0121] Sealing curing hardness: After mixing components A and B evenly in proportion, the mixture is cured for 72 hours at 23±2℃ and 50±5%RH under completely moisture-free conditions. The sealing curing hardness of the silicone sealant prepared in the above example is then tested according to GB / T 531. After storing components A and B at room temperature for 6 months, the sealing curing hardness is tested again.

[0122] Adhesion strength: The adhesion strength of the silicone sealant prepared in the above examples to PET film and aluminum-plastic film was tested according to GB / T 7124, and the adhesion strength of components A and B was tested again after being stored at room temperature for 6 months.

[0123] "Double 85" 1000h: The sample is cured at 23±2℃ and 50±5%RH for 72h, then placed in a constant temperature and humidity environment of 85℃ and 85%RH for 1000h. After being removed, it is cured at 23±2℃ and 50±5%RH for 24h. Then the bonding strength is tested.

[0124] Thermal conductivity: tested according to ISO 22007.

[0125] Flame retardancy rating: Measured according to UL-94 test method.

[0126] Table 1 Performance Tests

[0127]

[0128] As can be seen from Table 1, the silicone sealant prepared in the embodiments of the present invention has high open-cure hardness and closed-cure hardness in the initial state, indicating that it has a high degree of curing both when exposed to moisture and when completely isolated from moisture; at the same time, it has high bonding strength. In contrast, although the open-cure hardness of Comparative Examples 1-3 is also high, the closed-cure hardness is significantly lower, and the bonding strength is also lower.

[0129] The silicone sealant prepared in this embodiment of the invention has good storage stability, and its bonding strength did not decrease significantly after being stored at room temperature for 6 months; it also has good resistance to high temperature and high humidity, and the bonding strength retention rate is above 88% after aging with double 85 for 1000 hours.

[0130] In Example 10, a conventional silicon nitride hydroxyl scavenger was used. Compared with Example 1, its adhesion strength and hardness were slightly reduced, indicating that the acid anhydride derivative hydroxyl scavenger is superior to the silicon nitride hydroxyl scavenger.

[0131] Furthermore, the silicone sealant prepared in the embodiments of the present invention meets the requirements of SVHC, which may be related to the use of raw materials with a D3-D10 cyclic content of <0.1% in the base polymer; and the silicone sealant prepared in the embodiments of the present invention has a high thermal conductivity, all greater than 1.0 W / (m·K), and its flame retardancy rating meets the V-0 level.

[0132] The above description is merely a preferred embodiment of the present invention and is not intended to limit the implementation of the present invention. Those skilled in the art can easily make corresponding modifications or alterations based on the main concept and spirit of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection claimed in the claims.

Claims

1. A two-component condensation type heat conductive silicone sealant, characterized by, Components comprising the following mass parts: A component: Alpha, omega-dihydroxypolydimethylsiloxane 0~90 parts, Side chain containing epoxy group end hydroxyl polydimethylsiloxane 10~100 parts, Thermal conductive filler I 250~330 parts, Deep curing accelerator 1~5 parts, The deep curing accelerator in the A component is a compound of white carbon black, water and emulsifier in a mass ratio of 100: (5~50): (0.5~5), and the total amount of alpha, omega-dihydroxypolydimethylsiloxane and side chain containing epoxy group end hydroxyl polydimethylsiloxane is 100 parts; B component: Alkoxyl-terminated polydimethylsiloxane 0~90 parts, Alkoxyl-terminated polydimethylsiloxane containing end amino group 10~100 parts, Thermal conductive filler II 250~330 parts, Plasticizer 0~50 parts, Coupling agent 0~20 parts, Catalyst 0.05~0.5 parts, Hydroxyl scavenger 1.0~5.0 parts, The hydroxyl scavenger is an acid anhydride derivative or a silazane compound, and the total amount of alkoxyl-terminated polydimethylsiloxane, alkoxyl-terminated polydimethylsiloxane containing end amino group and plasticizer is 100 parts; The mass ratio of the A component and the B component is 1: (0.5~1.2).

2. The two-component condensation type thermal conductive silicone sealant according to claim 1, characterized by, The structure formula of the side chain containing epoxy group end hydroxyl polydimethylsiloxane in the A component is as follows: ； Wherein, m is an integer of 10~5000, n is an integer of 1~500, and 100 R1is methyl, ethyl or epoxypropoxypropyl; R2and R3are independently methyl or ethyl.

3. The two-component condensation type thermal conductive silicone sealant according to claim 1, characterized by, The viscosity of the alpha, omega-dihydroxypolydimethylsiloxane in the A component at 25℃ is 400~10000 cps; The mass fraction is 40~80 parts.

4. The two-component condensation type thermal conductive silicone sealant according to claim 3, characterized by, The viscosity of the alpha, omega-dihydroxypolydimethylsiloxane in the A component at 25℃ is 700~3000 cps.

5. The two-component condensation type thermal conductive silicone sealant according to claim 1, characterized by, The emulsifier in the A component is at least one of glycerol monostearate, soybean phospholipid, sodium dodecyl sulfate, fatty acid soap, polyoxyethylene ether, polyoxypropylene ether and polyether silicone oil.

6. The two-component condensation type thermal conductive silicone sealant according to claim 1, characterized by, The structure formula of the alkoxyl-terminated polydimethylsiloxane containing end amino group in the B component is as follows: ； Wherein, m1is an integer of 50~5000; R5and R6are independently methoxy, ethoxy or propoxy; R7is aminopropyl, aminoethyl aminopropyl, diethylaminopropyl, diethylaminomethyl, n-butylaminopropyl or n-butylaminomethyl.

7. The two-component condensation type thermal conductive silicone sealant according to claim 1, characterized by, The alkoxyl-terminated polydimethylsiloxane in the B component is at least one of dimethoxyl-terminated polydimethylsiloxane, trimethoxyl-terminated polydimethylsiloxane, diethoxyl-terminated polydimethylsiloxane, triethoxyl-terminated polydimethylsiloxane, trimethoxysilyl ethyl-terminated polydimethylsiloxane and triethoxysilyl ethyl-terminated polydimethylsiloxane; its viscosity at 25℃ is 400~10000 cps; and its mass fraction is 30~50 parts.

8. The two-component condensation type thermal conductive silicone sealant according to claim 7, characterized by, The viscosity of the alkoxyl-terminated polydimethylsiloxane in the B component at 25℃ is 700~5000 cps.

9. The two-component condensation type thermal conductive silicone sealant according to claim 1, characterized by, The heat-conductive filler I and the heat-conductive filler II are each independently at least one of aluminum hydroxide, aluminum oxide, quartz powder, zinc oxide, aluminum nitride, boron nitride, magnesium oxide, and zinc borate.

10. The two-component condensation type thermal conductive silicone sealant according to claim 1, characterized by, The plasticizer in the B component is polydimethylsiloxane with a viscosity of 50-500 cps at 25°C; and / or The coupling agent is at least one of an amino silane coupling agent, a bis-amino silane coupling agent, a bis-amino silane coupling agent oligomer, and 1,3,5-tris(trimethoxysilylpropyl) polyisocyanate; and / or The catalyst is at least one of dibutyl tin dilaurate, dioctyl tin dilaurate, dibutyl tin diacetate, dimethyl tin dineodecanoate, and chelated organotin; and / or The hydroxyl scavenger is an anhydride derivative.

11. The two-component condensation type thermal conductive silicone sealant according to claim 1, characterized by, The mass ratio of the A component to the B component is 1: (0.8-1.2).

12. The method of producing the two-component condensation type heat conductive silicone sealant according to any one of claims 1 to 11, characterized by, The method comprises the following steps: (S1) Preparation of the A component: α, ω-dihydroxyl polydimethylsiloxane, side chain epoxy-containing terminal hydroxyl polydimethylsiloxane, heat-conductive filler I, and deep curing accelerator are added into a stirred tank for stirring and mixing, and vacuum degassing is performed, followed by packaging, moisture isolation, and storage to obtain the A component; (S2) Preparation of the B component: alkoxy-terminated polydimethylsiloxane, amino-containing alkoxy-terminated polydimethylsiloxane, heat-conductive filler II, and plasticizer are added into a stirred tank for stirring and mixing, and vacuum dehydration is performed, followed by cooling to room temperature, and then adding a coupling agent, a catalyst, and a hydroxyl scavenger, and vacuum stirring at room temperature, packaging, and moisture isolation and storage to obtain the B component.

13. The method of claim 12, wherein, In step (S1), the stirring and mixing and vacuum degassing are performed at a rotation speed of 200-500 r / min for 30-90 min, and the vacuum degree is maintained at -0.05 to -0.1 Mpa; in step (S2), the stirring and mixing and vacuum dehydration are performed at a rotation speed of 200-500 r / min at 80-150°C for 30-90 min, and the vacuum degree is maintained at -0.05 to -0.1 Mpa; and the vacuum stirring is performed at a rotation speed of 200-500 r / min for 10-60 min while maintaining the vacuum degree at -0.05 to -0.1 Mpa.

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