Preparation method and application of tackifier for organosilicone heat-conducting pouring sealant

Abstract

The invention discloses a preparation method and application of a tackifier for an organic silicon heat-conducting pouring sealant, and relates to the technical field of tackifiers and pouring sealants applying the tackifiers. According to the scheme, diphenylsilanediol, trimethylolpropane monoallyl ether and other components are adopted as raw materials to prepare a tackifier, on the basis, vinyl silicone oil, the tackifier, hydrogen-containing silicone oil, alkynyl cyclohexanol and other components are mixed to prepare the organic silicon pouring sealant, aluminum oxide and aluminum hydroxide are selected to be compounded as filler, and the filler is selected to be mixed with the tackifier to prepare the organic silicon pouring sealant. According to the organic silicon pouring sealant, the heat-conducting property and the flame-retardant property of the organic silicon pouring sealant are improved, the filler is pretreated by adopting the branched bonding accelerant, the dispersing property and the system compatibility of the filler are improved, the finally prepared organic silicon pouring sealant is excellent in heat-conducting property and flame-retardant property, and the bonding property of the pouring sealant is greatly improved; the mechanical property is relatively excellent.

Description

Technical Field

[0001] The present invention relates to the technical field of potting adhesives for tackifiers and their applications, and specifically to a preparation method and application of a tackifier for silicone thermal conductive potting adhesives. Background Art

[0002] Silicone potting adhesives have good high and low temperature resistance, weather resistance, electrical insulation, chemical reagent resistance, etc., and are one of the adhesives that have received extensive attention nowadays. However, with the development of electronic components towards high-end, refined and intelligent directions, enterprises' requirements for the bonding strength, mechanical strength and other properties of silicone potting adhesives are constantly increasing. Therefore, which tackifiers are used to increase the viscosity of silicone potting adhesives and how to improve the mechanical properties of silicone potting adhesives have become important topics for R & D personnel.

[0003] Patent CN201210421580.2 discloses a preparation method of a tackifier for addition-type silicone potting adhesives. This patent uses raw materials such as acrylic hydroxy esters, glycidyl ether alkoxysilanes, and titanate to react to prepare a new type of tackifier. After adding the synthesized tackifier to the silicone potting adhesive, the bonding performance, water resistance and thermal conductivity of the potting adhesive are all improved. Patent CN201811193114.7 discloses the preparation and application of a tackifier for addition-type silicone thermal conductive potting adhesives. This patent introduces vinyl groups and aniline groups into the structure of the tackifier. The vinyl participates in the reaction of the addition-type silicone thermal conductive potting adhesive, and the potting adhesive and the tackifier are bonded through a chemical bond reaction. The introduction of active groups greatly improves the bonding performance of the potting adhesive. However, the processing cost of the tackifiers disclosed in the above two solutions is relatively high, and the tackifying effect of the prepared tackifiers still cannot meet the actual application requirements.

[0004] At the same time, Patent CN202411120893.3, a low-viscosity high-thermal-conductivity silicone bonding potting adhesive and its preparation method, uses two tackifiers in combination. The prepared thermal conductive potting adhesive has a high thermal conductivity, and the potting adhesive has a good bonding effect on substrates such as aluminum, PVC, PMMA, and PCB boards. However, in this solution, the thermal conductive filler is not optimized and modified, and the thermal conductive filler is prone to agglomeration, affecting the comprehensive bonding performance of the potting adhesive.

[0005] Based on the above situation, the present application discloses a preparation method and application of a tackifier for silicone thermal conductive potting adhesives, modifies the tackifier, and improves the bonding performance and mechanical properties of the silicone potting adhesive. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method and application of a tackifier for silicone thermal conductive potting adhesives to solve the problems raised in the above background art.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: A preparation method of a tackifier for silicone thermal conductive potting adhesive, comprising the following steps: Step 1: Mix 3-glycidoxypropyl dimethoxymethylsilane, diphenylsilanediol and barium hydroxide, stir evenly, heat up to 80°C - 85°C under a nitrogen atmosphere, react for 3h - 5h, add trimethylolpropane monoallyl ether, and continue to react at 80°C - 90°C for 3h - 5h, purify and separate, and vacuum dry at 60°C - 70°C to obtain a linear adhesion promoter; Mix 3-glycidoxypropyl trimethoxysilane, diphenylsilanediol and barium hydroxide, stir evenly, heat up to 80°C - 85°C under a nitrogen atmosphere, react for 3h - 5h, add trimethylolpropane monoallyl ether, and continue to react at 80°C - 90°C for 3h - 5h, purify and separate, and vacuum dry at 60°C - 70°C to obtain a branched adhesion promoter; Step 2: Compound and mix the linear adhesion promoter and the branched adhesion promoter to obtain the tackifier for the potting adhesive.

[0008] Preferably, when preparing the linear adhesion promoter, the molar ratio of 3-glycidoxypropyl dimethoxymethylsilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1:1.

[0009] Preferably, when preparing the branched adhesion promoter, the molar ratio of 3-glycidoxypropyl trimethoxysilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1.5:1.5.

[0010] Preferably, in Step 1, the dosage of barium hydroxide is 2% - 3% of the total molar amount of the reaction monomers in the system; in Step 2, the mass ratio of the linear adhesion promoter to the branched adhesion promoter is (3 - 4):1.

[0011] Preferably, a tackifier prepared by the preparation method of a tackifier for silicone thermal conductive potting adhesive according to any one of the above.

[0012] Preferably, an application of a tackifier for silicone thermal conductive potting adhesive, the tackifier is applied to silicone potting adhesive, and the specific steps are: Step A: Mix the filler and ethanol, add the branched adhesion promoter, react at 80°C - 85°C for 3h - 4h, centrifuge at a speed of 9000r / min - 10000r / min for 5min - 6min, wash, and vacuum dry to obtain a pretreated filler; the filler is any one or a combination of alumina, aluminum hydroxide, and zinc oxide; Step B: Mix vinyl silicone oil and pretreated filler, add the above-mentioned tackifier, stir for 5 min to 10 min, degas under vacuum for 15 min to 20 min, let stand for 2 h to 3 h, then add hydrogen-containing silicone oil, ethynylcyclohexanol and Karstedt catalyst, mix evenly, and degas under vacuum for 15 min to 20 min to obtain the silicone thermal conductive potting adhesive.

[0013] Preferably, in Step B, the specific amounts of each component are as follows: by mass, 100 parts of vinyl silicone oil, 160 - 180 parts of pretreated filler, 2 - 3 parts of tackifier, 7 - 8 parts of hydrogen-containing silicone oil, 0.01 - 0.02 parts of ethynylcyclohexanol, and 0.3 - 0.4 parts of Karstedt catalyst.

[0014] Preferably, in Step A, the filler is a compound of alumina and aluminum hydroxide, and the mass ratio of alumina to aluminum hydroxide is 4:1. The mass ratio of the filler to the branched adhesion promoter is 1:6. The particle size of the alumina is 4 μm to 5 μm, and the particle size of the aluminum hydroxide is 2 μm to 3 μm.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention discloses a tackifier for silicone thermal conductive potting adhesive. The scheme first uses diphenylsilanediol, trimethylolpropane monoallyl ether and other components as raw materials to react and prepare the tackifier. When 3-glycidoxypropyl dimethoxymethylsilane is used to participate in the reaction, it is bridged by diphenylsilanediol to prepare a polysiloxane containing epoxy groups, vinyl groups and phenyl groups (linear adhesion promoter), presenting a linear structure; while when 3-glycidoxypropyl trimethoxysilane is used to participate in the reaction, due to the existence of multiple reaction grafting points in 3-glycidoxypropyl trimethoxysilane, a branched polysiloxane (branched adhesion promoter) is prepared, and this branched polysiloxane also contains epoxy groups, vinyl groups and phenyl groups; the two polysiloxanes are compounded to obtain the tackifier. The presence of vinyl groups can react with the silicon-hydrogen bonds in the system, and the introduction of epoxy groups can improve the adhesion strength of the potting adhesive.

[0016] It should be emphasized that in this solution, 3-glycidoxypropyl dimethoxymethylsilane is first used as a reaction raw material. This substance has a disiloxane functionality. Therefore, the solution defines that "the molar ratio of 3-glycidoxypropyl dimethoxymethylsilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1:1", so as to react to generate a linear adhesion promoter. The active groups in the linear adhesion promoter participate in the system reaction to improve the adhesion performance. While 3-glycidoxypropyl trimethoxysilane has a trisiloxane functionality. Therefore, the solution defines that "the molar ratio of 3-glycidoxypropyl trimethoxysilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1.5:1.5". Under this parameter ratio, a branched polysiloxane is generated. The branched polysiloxane (branched adhesion promoter) partially replaces the linear adhesion promoter, and the crosslinking density of the system is increased through the branched structure, comprehensively improving the adhesion performance and mechanical properties of the silicone potting adhesive. However, if the branched polysiloxane (branched adhesion promoter) is excessive, it will instead reduce the performance of the silicone potting adhesive. Therefore, this solution defines that "the mass ratio of the linear adhesion promoter to the branched adhesion promoter is (3~4):1". Through this defined parameter, a tackifier is prepared by compounding, and it has the most excellent improvement in the mechanical properties, adhesion performance, etc. of the silicone potting adhesive.

[0017] On this basis, the solution mixes components such as vinyl silicone oil, tackifier, hydrogen-containing silicone oil, and ethynylcyclohexanol to prepare a silicone potting adhesive. Among them, alumina and aluminum hydroxide are selected as the fillers in combination to improve the thermal conductivity and flame retardancy of the silicone potting adhesive, and the branched adhesion promoter is used to pretreat the fillers to improve the dispersion performance and system compatibility of the fillers. Finally, the prepared silicone potting adhesive not only has excellent thermal conductivity and flame retardancy, but also has a greatly improved adhesion performance of the potting adhesive, and the mechanical properties are also excellent. It should be reminded that in this solution, in order to optimize the modification effect of the fillers, the branched adhesion promoter is used to modify them instead of the linear adhesion promoter. The purpose is to introduce more active groups to participate in the system reaction, and the interfacial action of the fillers in the system after pretreatment modification is more excellent and the compatibility is higher.

[0018] The present invention discloses a tackifier for a silicone thermal conductive potting adhesive and a silicone potting adhesive using the same. The solution is adjusted based on the current silicone potting adhesive formula, and the preparation process and dosage of the tackifier are improved. Finally, the prepared silicone potting adhesive has excellent adhesion performance and can be widely used in the encapsulation of electronic components, with high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the potting adhesive of Sample 2 prepared by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] In the following embodiments, the particle size of the alumina is 5 μm, and the particle size of the aluminum hydroxide is 3 μm; vinyl silicone oil: terminal vinyl silicone oil, with a vinyl content of 0.28% and a viscosity of 500 cp, provided by Zhejiang Runhe Chemical New Materials Co., Ltd.; the hydrogen content of the hydrogen-containing silicone oil is 0.18% and the viscosity is 80 cp, provided by Zhejiang Runhe Chemical New Materials Co., Ltd.

[0022] Example 1: A preparation method of a tackifier for organosilicon thermal conductive potting adhesive, comprising the following steps: Step 1: Mix 3-glycidoxypropyl dimethoxymethylsilane (0.1 mol), diphenylsilanediol (0.1 mol) and barium hydroxide (7.5 mmol), stir evenly, heat to 80 °C under a nitrogen atmosphere, react for 5 h, add trimethylolpropane monoallyl ether (0.1 mol), and continue to react at 80 °C for 5 h, purify and separate, and vacuum dry at 70 °C to obtain a linear adhesion promoter. The molar ratio of 3-glycidoxypropyl dimethoxymethylsilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1:1.

[0023] Mix 3-glycidoxypropyl trimethoxysilane (0.1 mol), diphenylsilanediol (0.15 mol) and barium hydroxide (10 mmol), stir evenly, heat to 85 °C under a nitrogen atmosphere, react for 3 h, add trimethylolpropane monoallyl ether (0.15 mol), and continue to react at 90 °C for 3 h, purify and separate, and vacuum dry at 70 °C to obtain a branched adhesion promoter. The molar ratio of 3-glycidoxypropyl trimethoxysilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1.5:1.5.

[0024] Step 2: In terms of parts by mass, compound and mix 2.25 parts of the linear adhesion promoter and 0.75 parts of the branched adhesion promoter to obtain the tackifier for the potting adhesive. The mass ratio of the linear adhesion promoter to the branched adhesion promoter is 3:1.

[0025] Example 2: A preparation method of a tackifier for organosilicon thermal conductive potting adhesive, comprising the following steps: Step 1: Mix 3-glycidoxypropyl dimethoxymethylsilane (0.1 mol), diphenylsilanediol (0.1 mol) and barium hydroxide (7.5 mmol), stir evenly, heat up to 85 °C under a nitrogen atmosphere, react for 4 h, add trimethylolpropane monoallyl ether (0.1 mol), and continue to react at 85 °C for 4 h. Then, carry out purification and separation, and vacuum dry at 70 °C to obtain a linear adhesion promoter. The molar ratio of 3-glycidoxypropyl dimethoxymethylsilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1:1.

[0026] Mix 3-glycidoxypropyl trimethoxysilane (0.1 mol), diphenylsilanediol (0.15 mol) and barium hydroxide (10 mmol), stir evenly, heat up to 85 °C under a nitrogen atmosphere, react for 4 h, add trimethylolpropane monoallyl ether (0.15 mol), and continue to react at 85 °C for 4 h. Then, carry out purification and separation, and vacuum dry at 70 °C to obtain a branched adhesion promoter. The molar ratio of 3-glycidoxypropyl trimethoxysilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1.5:1.5.

[0027] Step 2: Mix 2.4 parts by mass of the linear adhesion promoter and 0.6 parts by mass of the branched adhesion promoter to obtain the tackifier for potting adhesive. The mass ratio of the linear adhesion promoter to the branched adhesion promoter is 4:1.

[0028] Example 3: A preparation method of a tackifier for organosilicon thermal conductive potting adhesive, comprising the following steps: Step 1: Mix 3-glycidoxypropyl dimethoxymethylsilane (0.1 mol), diphenylsilanediol (0.1 mol) and barium hydroxide (7.5 mmol), stir evenly, heat up to 85 °C under a nitrogen atmosphere, react for 3 h, add trimethylolpropane monoallyl ether (0.1 mol), and continue to react at 90 °C for 3 h. Then, carry out purification and separation, and vacuum dry at 70 °C to obtain a linear adhesion promoter. The molar ratio of 3-glycidoxypropyl dimethoxymethylsilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1:1.

[0029] Mix 3-glycidoxypropyl trimethoxysilane (0.1 mol), diphenylsilanediol (0.15 mol) and barium hydroxide (10 mmol), stir evenly, heat up to 80 °C under a nitrogen atmosphere, react for 5 h, add trimethylolpropane monoallyl ether (0.15 mol), and continue to react at 80 °C for 5 h. Then, carry out purification and separation, and vacuum dry at 70 °C to obtain a branched adhesion promoter. The molar ratio of 3-glycidoxypropyl trimethoxysilane, diphenylsilanediol, and trimethylolpropane monoallyl ether is 1:1.5:1.5.

[0030] Step 2: Take 2 parts by mass of linear adhesion promoter and 0.5 part by mass of branched adhesion promoter, compound and mix them to obtain the tackifier for potting adhesive. The mass ratio of the linear adhesion promoter to the branched adhesion promoter is 4:1.

[0031] Example 4: A preparation method of an organosilicon heat-conducting potting adhesive, comprising the following steps: Step A: Mix 5 g of filler and 120 mL of ethanol, add the branched adhesion promoter, react at 85 °C for 3 h, centrifuge at a speed of 10,000 r / min for 5 min, wash, and vacuum dry to obtain pretreated filler; the filler is a compound of alumina and aluminum hydroxide, and the mass ratio of alumina to aluminum hydroxide is 4:1. The mass ratio of the filler to the branched adhesion promoter is 1:6.

[0032] Step B: Mix vinyl silicone oil and pretreated filler, add the tackifier, stir for 10 min, vacuum degas for 15 min, stand for 2 h, then add hydrogen-containing silicone oil, ethynyl cyclohexanol and Karstedt catalyst, mix evenly, and vacuum degas for 20 min to obtain the organosilicon heat-conducting potting adhesive.

[0033] Take the tackifiers prepared in Examples 1 to 3, and prepare organosilicon potting adhesive samples 1 to 3 according to the method disclosed in Example 4; when preparing samples 1 to 3, the filler modification also correspondingly uses the branched adhesion promoters prepared in Examples 1 to 3 respectively; the specific dosages of samples 1 to 3 are shown in Table 1 below: Table 1 Specific component dosages of samples 1 to 3 (by mass) Comparative Example 1: The sample prepared in Comparative Example 1 is compared with Sample 2. In Comparative Example 1, a linear adhesion promoter is used as the tackifier, and no branched adhesion promoter is added to the tackifier.

[0034] A preparation method of an organosilicon heat-conducting potting adhesive, comprising the following steps: Step A: Mix 5 g of filler and 120 mL of ethanol, add the branched adhesion promoter, react at 85 °C for 3 h, centrifuge at a speed of 10,000 r / min for 5 min, wash, and vacuum dry to obtain pretreated filler; the filler is a compound of alumina and aluminum hydroxide, and the mass ratio of alumina to aluminum hydroxide is 4:1. The mass ratio of the filler to the branched adhesion promoter is 1:6.

[0035] Step B: Mix vinyl silicone oil and pretreated filler, add the linear adhesion promoter, stir for 10 min, vacuum degas for 15 min, stand for 2 h, then add hydrogen-containing silicone oil, ethynyl cyclohexanol and Karstedt catalyst, mix evenly, and vacuum degas for 20 min to obtain the organosilicon heat-conducting potting adhesive (Sample 4).

[0036] The specific amounts of each component are as follows: by mass, 100 parts of vinyl silicone oil, 165 parts of pretreated filler, 3 parts of linear adhesion promoter, 8 parts of hydrogen-containing silicone oil, 0.01 part of ethynylcyclohexanol, and 0.35 part of Karstedt catalyst.

[0037] The specific preparation steps of the branched adhesion promoter and linear adhesion promoter used therein are as follows: Mix 3-glycidoxypropyl dimethoxymethylsilane (0.1 mol), diphenylsilanediol (0.1 mol), and barium hydroxide (7.5 mmol), stir evenly, heat to 85 °C under a nitrogen atmosphere, react for 4 h, add trimethylolpropane monoallyl ether (0.1 mol), and continue to react at 85 °C for 4 h. Then, perform purification and separation, and vacuum dry at 70 °C to obtain the linear adhesion promoter.

[0038] Mix 3-glycidoxypropyl trimethoxysilane (0.1 mol), diphenylsilanediol (0.15 mol), and barium hydroxide (10 mmol), stir evenly, heat to 85 °C under a nitrogen atmosphere, react for 4 h, add trimethylolpropane monoallyl ether (0.15 mol), and continue to react at 85 °C for 4 h. Then, perform purification and separation, and vacuum dry at 70 °C to obtain the branched adhesion promoter.

[0039] Comparative Example 2: The sample prepared in Comparative Example 2 was compared with Sample 2. In Comparative Example 2, a linear adhesion promoter was used as the filler modifier.

[0040] A preparation method of an organosilicon thermal conductive potting adhesive includes the following steps: Step A: Mix 5 g of filler and 120 mL of ethanol, add the linear adhesion promoter, react at 85 °C for 3 h, centrifuge at a speed of 10000 r / min for 5 min, wash, and vacuum dry to obtain the pretreated filler; the filler is a compound of alumina and aluminum hydroxide, and the mass ratio of alumina to aluminum hydroxide is 4:1. The mass ratio of the filler to the linear adhesion promoter is 1:6.

[0041] Step B: Mix the vinyl silicone oil and the pretreated filler, add the tackifier, stir for 10 min, vacuum degas for 15 min, let stand for 2 h, then add the hydrogen-containing silicone oil, ethynylcyclohexanol, and Karstedt catalyst, mix evenly, and vacuum degas for 20 min to obtain the organosilicon thermal conductive potting adhesive (Sample 5).

[0042] The specific amounts of each component are as follows: by mass, 100 parts of vinyl silicone oil, 165 parts of pretreated filler, 3 parts of tackifier, 8 parts of hydrogen-containing silicone oil, 0.01 part of ethynylcyclohexanol, and 0.35 part of Karstedt catalyst.

[0043] The specific preparation steps of the tackifier and linear adhesion promoter used therein are as follows: Step 1: Mix 3-glycidoxypropyl dimethoxymethylsilane (0.1 mol), diphenylsilanediol (0.1 mol) and barium hydroxide (7.5 mmol), stir evenly, heat up to 85 °C under nitrogen atmosphere, react for 4 h, add trimethylolpropane monoallyl ether (0.1 mol), continue to react at 85 °C for 4 h, purify and separate, and dry in vacuum at 70 °C to obtain a linear adhesion promoter.

[0044] Mix 3-glycidoxypropyltrimethoxysilane (0.1 mol), diphenylsilanediol (0.15 mol) and barium hydroxide (10 mmol), stir evenly, heat up to 85 °C under nitrogen atmosphere, react for 4 h, add trimethylolpropane monoallyl ether (0.15 mol), continue to react at 85 °C for 4 h, purify and separate, and dry in vacuum at 70 °C to obtain a branched adhesion promoter.

[0045] Step 2: Take 2.4 parts by mass of the linear adhesion promoter and 0.6 parts by mass of the branched adhesion promoter, mix them compoundly to obtain the tackifier for the potting adhesive. The mass ratio of the linear adhesion promoter to the branched adhesion promoter is 4:1.

[0046] Comparative Example 3: The sample prepared in Comparative Example 2 is compared with Sample 2. In Comparative Example 3, the branched adhesion promoter is not used to modify the filler, and only the silane coupling agent KH-570 is used.

[0047] A preparation method of an organosilicon thermal conductive potting adhesive includes the following steps: Step A: Mix 5 g of filler and 120 mL of ethanol, add the silane coupling agent KH-570, react at 85 °C for 3 h, centrifuge at 10000 r / min for 5 min, wash, and dry in vacuum to obtain a pretreated filler; the filler is a compound of alumina and aluminum hydroxide, and the mass ratio of alumina to aluminum hydroxide is 4:1. The mass ratio of the filler to the silane coupling agent KH-570 is 1:4.

[0048] Step B: Mix vinyl silicone oil and the pretreated filler, add the tackifier, stir for 10 min, degas in vacuum for 15 min, let stand for 2 h, then add hydrogen-containing silicone oil, ethynylcyclohexanol and Karstedt catalyst, mix evenly, and degas in vacuum for 20 min to obtain the organosilicon thermal conductive potting adhesive (Sample 6).

[0049] The specific dosage of each component is as follows: by mass, 100 parts of vinyl silicone oil, 165 parts of pretreated filler, 3 parts of tackifier, 8 parts of hydrogen-containing silicone oil, 0.01 part of ethynylcyclohexanol, and 0.35 part of Karstedt catalyst.

[0050] Among them, the specific preparation steps of the tackifier are as follows: Step 1: Mix 3-glycidoxypropyl dimethoxymethylsilane (0.1 mol), diphenylsilanediol (0.1 mol) and barium hydroxide (7.5 mmol), stir evenly, heat up to 85 °C under a nitrogen atmosphere, react for 4 h, add trimethylolpropane monoallyl ether (0.1 mol), and continue to react at 85 °C for 4 h. Purify and separate, and dry under vacuum at 70 °C to obtain a linear adhesion promoter.

[0051] Mix 3-glycidoxypropyl trimethoxysilane (0.1 mol), diphenylsilanediol (0.15 mol) and barium hydroxide (10 mmol), stir evenly, heat up to 85 °C under a nitrogen atmosphere, react for 4 h, add trimethylolpropane monoallyl ether (0.15 mol), and continue to react at 85 °C for 4 h. Purify and separate, and dry under vacuum at 70 °C to obtain a branched adhesion promoter.

[0052] Step 2: Take 2.4 parts by mass of the linear adhesion promoter and 0.6 parts by mass of the branched adhesion promoter, mix them compoundly to obtain the tackifier for potting adhesive. The mass ratio of the linear adhesion promoter to the branched adhesion promoter is 4:1.

[0053] Detection experiment: According to the above examples and comparative examples, prepare potting adhesive samples 1-3 and samples 4-6 (prepared according to the methods disclosed in Comparative Examples 1-3), and conduct the following tests: 1. Pour each sample into a mold and cure at 130 °C for 2 h to obtain specimens. Detect the tensile strength of each specimen according to the method disclosed in GB / T528-2009. The specimens are dumbbell-shaped, with a thickness of 2 mm and a tensile rate of 500 mm / min; according to the method disclosed in GB / T11205-2009, test the thermal conductivity, and the specimen size is 150 mm×150 mm×3 mm; detect the limiting oxygen index of each specimen according to the method disclosed in GB / T10707-2008.

[0054] 2. According to the method disclosed in GB / T13936-2014, test the adhesion strength of the potting adhesive sample to the aluminum sheet; when testing, clean the surface of the aluminum sheet with alcohol and deionized water, and conduct the standard test. The curing temperature is 130 °C, the curing time is 2 h, the bonding area between the potting adhesive and the aluminum sheet is 25 mm×12.5 mm, the thickness of the potting adhesive is 2 mm, and the tensile rate is 50 mm / min.

[0055] High temperature resistance performance: Place the aluminum sheet specimen bonded with the potting adhesive sample in a constant temperature oven at 350 °C and bake for 24 h, then cool, observe whether there are cracks or debonding in the bonded part of the aluminum sheet specimen, and record the data.

[0056] 3. The volume resistivity was tested according to the method disclosed in GB / T 1692-2008, and the specimen size was 100 mm × 100 mm × 2 mm.

[0057] The test data are shown in Table 2 below; " / " indicates that the data was not tested or not recorded. (The filler dosage in Samples 4-6 was not adjusted, and the products prepared from Samples 1-3 were sufficient to prove that the potting adhesive had excellent thermal conductivity, limiting oxygen index and insulation performance. Therefore, the inventors did not test the thermal conductivity and limiting oxygen index of Samples 4-6, and the data was not recorded, marked with " / ") Table 2 Conclusion: From the data in the above table, when preparing silicone potting adhesive Samples 1-3 with the tackifier disclosed in Examples 1-3, the tackifier dosage of Samples 1 and 2 was 3 parts, while the tackifier dosage of Sample 3 was 2.5 parts. Therefore, the tensile strength and bonding strength of Samples 1 and 2 were significantly better than those of Sample 3; and the mass ratio of the linear bonding promoter to the branched bonding promoter in Sample 1 was 3:1, and the mass ratio of the linear bonding promoter to the branched bonding promoter in Sample 2 was 4:1. From the result data, it can be seen that the comprehensive performance of Sample 2 was the most excellent; at the same time, the dosage of the pretreated filler in Sample 1 was significantly lower than that in Samples 2 and 3, and finally the limiting oxygen index of Sample 1 was also slightly lower than that in Samples 2 and 3.

[0058] Among Samples 4-6 (prepared according to the methods disclosed in Comparative Examples 1-3), Sample 4 only used a linear bonding promoter as the tackifier and did not add a branched bonding promoter for auxiliary compounding; Sample 5 used a linear bonding promoter to modify the filler instead of a branched bonding promoter, while Sample 6 used a conventional silane coupling agent KH-570 to modify the filler. From the test results, it can be seen that the comprehensive performance of Sample 4 was significantly worse than that of other samples, which was sufficient to prove the improvement of the product performance by the technical feature of "using a linear bonding promoter and a branched bonding promoter for auxiliary compounding"; and from the data of Samples 5 and 6, it can be seen that using a branched bonding promoter to modify the filler had the most excellent effect.

[0059] The present invention discloses a tackifier for silicone thermal conductive potting adhesive and the silicone potting adhesive using the same. The scheme is adjusted on the basis of the existing silicone potting adhesive formula, and the preparation process and dosage of the tackifier are improved. Finally, the obtained silicone potting adhesive has excellent bonding performance and can be widely used in the encapsulation of electronic components, with high practicality.

[0060] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

Claims

1. A method for preparing a tackifier for silicone thermally conductive potting adhesive, characterized in that: The following steps are involved: Step 1: 3-glycidyloxypropyldimethoxymethylsilane, diphenylsilanediol and barium hydroxide are mixed and stirred evenly, heated to 80°C~85°C under a nitrogen atmosphere, reacted for 3h~5h, trimethylolpropane monoallyl ether is added, and the reaction is continued at 80°C~90°C for 3h~5h, purified and separated, and vacuum dried at 60°C~70°C to obtain a linear adhesion promoter; 3-glycidyloxypropyltrimethoxysilane, diphenylsilanediol and barium hydroxide are mixed and stirred evenly, heated to 80°C-85°C under a nitrogen atmosphere, reacted for 3h-5h, trimethylolpropane monoallyl ether is added, reacted at 80°C-90°C for 3h-5h, purified and separated, and vacuum dried at 60°C-70°C to obtain a branched adhesion promoter; Step 2: Compound and mix the linear adhesion promoter and the branched adhesion promoter to obtain the tackifier for the potting glue; the mass ratio of the linear adhesion promoter to the branched adhesion promoter is (3-4):

1.

2. The method for preparing a tackifier for silicone thermally conductive potting adhesive according to claim 1, characterized in that: When the linear adhesion promoter is prepared, the molar ratio of the 3-glycidyloxypropyl dimethoxymethylsilane, diphenylsilanediol and trimethylolpropane monoallyl ether is 1:1:

1.

3. The method for preparing a tackifier for silicone thermally conductive potting adhesive according to claim 1, characterized in that: When the branched adhesion promoter is prepared, the molar ratio of 3-glycidyloxypropyltrimethoxysilane, diphenylsilanediol and trimethylolpropane monoallyl ether is 1:1.5:1.

5.

4. The method for preparing a tackifier for silicone thermally conductive potting adhesive according to claim 1, characterized in that: In step 1, the amount of barium hydroxide used is 2% to 3% of the total molar amount of the reaction monomers in the system.

5. A tackifier prepared according to the method for preparing a tackifier for organic silicone thermal conductive potting adhesive according to any one of claims 1 to 4.

6. The use of a tackifier for silicone thermally conductive potting adhesive according to claim 5, characterized in that: The tackifier is applied to silicone potting adhesive, and the specific steps are as follows: Step A: Mix the filler and ethanol, add a branched adhesion promoter, react at 80°C to 85°C for 3h to 4h, centrifuge and wash, and vacuum dry to obtain a pretreated filler; the filler is a composite of any one or more of aluminum oxide, aluminum hydroxide, and zinc oxide; Step B: Mix the vinyl silicone oil and the pretreated filler, add a tackifier for the silicone thermal conductive potting glue, stir for 5 min to 10 min, vacuum degass for 15 min to 20 min, let stand for 2 h to 3 h, then add hydrogen-containing silicone oil, alkynyl cyclohexanol and Custer catalyst, mix evenly, vacuum degass for 15 min to 20 min, and obtain the silicone thermal conductive potting glue.

7. The use of a tackifier for silicone thermally conductive potting adhesive according to claim 6, characterized in that: In step B, the specific amount of each component is: in parts by mass, 100 parts of vinyl silicone oil, 160-180 parts of pretreated filler, 2-3 parts of tackifier, 7-8 parts of hydrogenated silicone oil, 0.01-0.02 parts of alkynyl cyclohexanol, and 0.3-0.4 parts of Custer catalyst.

8. The use of a tackifier for silicone thermally conductive potting adhesive according to claim 6, characterized in that: In step A, the filler is a composite of aluminum oxide and aluminum hydroxide, and the mass ratio of the aluminum oxide to the aluminum hydroxide is 4:

1.

9. The use of a tackifier for silicone thermally conductive potting adhesive according to claim 6, characterized in that: In step A, the mass ratio of the filler to the branched adhesion promoter is 1:

6.

10. The use of a tackifier for silicone thermally conductive potting adhesive according to claim 6, characterized in that: The particle size of the aluminum oxide is 4 μm to 5 μm, and the particle size of the aluminum hydroxide is 2 μm to 3 μm.

Images