Electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive, preparation method and application thereof

Abstract

The application belongs to polyurethane hot melt adhesive, and relates to a single-component silicon-modified heat-conducting polyurethane hot melt adhesive which can be electrically disassembled, a preparation method and application thereof. The single-component silicon-modified heat-conducting polyurethane hot melt adhesive contains a silicon-modified polyurethane prepolymer and a modified filler composition, and optionally a catalyst and a water absorbent, the modified filler composition contains a heat-conducting filler, an electrolyte salt and a silane coupling agent, and optionally a polar solvent compound; the bonding strength attenuation of the single-component silicon-modified heat-conducting polyurethane hot melt adhesive after being electrified under a voltage of 1-100 V is above 80%. The single-component silicon-modified heat-conducting polyurethane hot melt adhesive provided by the application has the advantages of good heat-conducting performance, excellent bonding performance and electrically disassembled advantage, and has a wide practical application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to polyurethane hot melt adhesive, and relates to a single-component silicone-modified thermally conductive polyurethane hot melt adhesive which can be electrically disassembled, a preparation method and application thereof. BACKGROUND

[0002] With the continuous development and maturity of the electronic industry, the size of internal devices of electronic equipment gradually decreases, and the device density in unit volume is higher and higher. The internal environment temperature of the equipment is rising when working, which makes the heat accumulate rapidly. At this time, the effective heat dissipation of the electronic equipment is crucial to the safe operation of the whole system. In electronic products such as smart phones and tablet computers, a thermally conductive structural adhesive is often needed. The common thermally conductive structural adhesive is polyurethane hot melt adhesive. The polyurethane hot melt adhesive takes isocyanate-terminated oligomer as the main body. The isocyanate group in the isocyanate-terminated oligomer can react with moisture in the air. After complete curing, a cross-linked chemical structure can be formed, thereby realizing high bonding strength. However, the covalent bond obtained by the reaction of the isocyanate group with moisture is irreversible, and the cross-linked structure is difficult to be destroyed. After complete curing, it is usually difficult to realize the disassembly of the adhesive. If the bonded materials need to be separated, a large external force, high temperature, chemical reagent and the like are often needed, and in the process of disassembling the adhesive, the bonded materials may be damaged, causing great economic loss.

[0003] In recent years, technology has given polyurethane hot melt adhesive the function of being disassembled under the condition of power supply by adding electrolyte salt in the polyurethane hot melt adhesive. However, although the existing electrically disassembled polyurethane hot melt adhesive can achieve the attenuation of bonding strength under the condition of power supply, the thermal conductivity is low, which is not conducive to application in structural bonding of bonding parts that are prone to heat and need to dissipate heat, such as heat that is difficult to dissipate continuously, which may also have a large safety hazard, and cannot meet the bonding requirements of high heat dissipation performance. Since the components of polyurethane hot melt adhesive are mainly high molecular materials, the thermal conductivity of high molecular materials is poor, and the existing thermal conductive polyurethane hot melt adhesive usually relies on the addition of thermal conductive fillers with excellent thermal conductivity performance in the adhesive component, and relies on the addition of high filling amount of thermal conductive fillers to give the polyurethane hot melt adhesive certain thermal conductivity. However, the thermal conductive filler is usually an inorganic non-metallic material, and the inorganic material has poor compatibility with the polyurethane material of the organic system, and usually needs to be surface treated and modified, and the corresponding adhesive material also needs to be modified. The existing technology uses silane to completely cap isocyanate, and cooperates with thermal conductive fillers to prepare a silane modified polyurethane adhesive with thermal conductivity function, but the existing thermal conductive silane modified polyurethane adhesive still has the problems of slow curing speed, the need for long time curing to establish high bonding strength, and the difficulty in disassembly after complete curing. In addition, the existing one-component polyurethane structural adhesive is prone to bubble problems during the curing process, which can easily form bonding defects and affect the bonding strength, and in the application of thermal conductive bonding, the bubbles can also form cavities to block the conduction of heat.

[0004] Therefore, it is urgent to develop a thermal conductive adhesive with good thermal conductivity, excellent bonding performance and electrically disassembled to meet the market demand for high-performance disassembled thermal conductive adhesive. SUMMARY

[0005] One of the purposes of the present application is to provide a one-component silane modified thermal conductive polyurethane hot melt adhesive with good thermal conductivity, excellent bonding performance and electrically disassembled.

[0006] The second purpose of the present application is to provide a preparation method of the above-mentioned one-component silane modified thermal conductive polyurethane hot melt adhesive.

[0007] The third purpose of the present application is to provide the application of the above-mentioned one-component silane modified thermal conductive polyurethane hot melt adhesive in electronic product bonding.

[0008] The application provides a single-component electrically detachable silicone modified heat-conductive polyurethane hot melt adhesive, which contains a silicone modified polyurethane prepolymer, a modified filler composition, and optionally a catalyst and a water absorbent, the modified filler composition contains a heat-conductive filler, an electrolyte salt, and a silane coupling agent, and optionally a polar solvent compound, the content of isocyanate groups in the single-component electrically detachable silicone modified heat-conductive polyurethane hot melt adhesive is 0.2-0.8%, and the mass ratio of the silicone modified polyurethane prepolymer to the modified filler composition is 1:(1.5-7.5); the adhesive strength attenuation of the single-component electrically detachable silicone modified heat-conductive polyurethane hot melt adhesive after being electrified under a voltage of 1-100 V is more than 80%.

[0009] The application provides a preparation method of the single-component electrically detachable silicone modified heat-conductive polyurethane hot melt adhesive, which comprises uniformly mixing the silicone modified polyurethane prepolymer, the modified filler composition, and optionally the catalyst and the water absorbent, so as to obtain the single-component electrically detachable silicone modified heat-conductive polyurethane hot melt adhesive.

[0010] The inventors of the application find through in-depth and extensive research that the existing single-component polyurethane hot melt adhesive has low adhesive strength and poor heat-conductive performance, mainly because: on the one hand, the existing single-component silane-terminated polyurethane adhesive is completely terminated by using a siloxane group, although the use of siloxane to terminate isocyanate is conducive to improving the compatibility of the heat-conductive filler and the polymeric adhesive, but the siloxane wet curing speed is much lower than the isocyanate wet curing speed, and a long time is usually needed for complete curing, and the adhesive strength after siloxane wet curing is also lower than the adhesive strength after isocyanate wet curing. On the other hand, the compatibility of the existing heat-conductive filler and the electrically detachable polyurethane hot melt adhesive is poor, and direct addition of the heat-conductive filler to the electrically detachable polyurethane hot melt adhesive is easy to form defects at the interface between the heat-conductive filler and the polyurethane hot melt adhesive, which is not conducive to the formation of an effective heat-conductive network, thereby affecting the realization of the heat-conductive function. On the other hand, the curing principle of the existing polyurethane hot melt adhesive is that the residual isocyanate groups in the polyurethane hot melt adhesive react with the moisture in the air, but the reaction of isocyanate and moisture produces carbon dioxide gas, which is sometimes difficult to discharge under conditions such as thick adhesive layers, and forms a gas cavity in the adhesive system, and the formation of the gas cavity blocks the heat transfer, thereby affecting the adhesive properties and heat-conductive properties of the adhesive.

[0011] The electrolyte salt, silane coupling agent and optional polar solvent compound are used to pre-treat the heat-conductive filler to obtain a modified filler composition, which can increase the compatibility of the heat-conductive filler and the polyurethane material, and the electrolyte salt introduced into the modified filler composition can provide the possibility of Faraday reaction of anions and cations under the condition of power supply. The modified filler composition introduced into the adhesive system can impart the electrical disassembly performance of the adhesive. In addition, the siloxane modified polyurethane prepolymer is used as the main body, which can greatly reduce the generation of bubbles in the curing process of the adhesive, avoid the formation of bonding defects due to bubbles to affect the bonding strength, and avoid the blockage of heat conduction due to the formation of cavities. In addition, the content of isocyanate groups in the siloxane modified polyurethane prepolymer is controlled within the range of the present application, which can well make up for the defect of lower bonding strength after siloxane wet curing. That is, the "bubble effect" avoided by siloxane and the post-curing tackiness of specific isocyanate groups can effectively impart the adhesive with good bonding strength. On the other hand, the compatibility of the siloxane modified polyurethane prepolymer with the heat-conductive filler is higher, which greatly increases the compatibility between the heat-conductive filler and the organic polymer adhesive, and can effectively volatilize the heat-conductive effect of the heat-conductive filler. That is, the "bubble cavity heat resistance" avoided by siloxane and the compatibility of siloxane can effectively impart the adhesive with good thermal conductivity. In summary, the one-component silane modified heat-conductive polyurethane hot melt adhesive provided by the present application has the advantages of good thermal conductivity, excellent bonding performance and electrical disassembly, and has a wide practical application prospect. DETAILED DESCRIPTION

[0012] The electrically detachable single-component silicone-modified heat-conductive polyurethane hot melt adhesive provided by the present application has a decay rate of bonding strength of more than 80% after being powered at a voltage of 1-100 V, and specifically can be 80%, 82%, 85%, 88%, 90%, 92%, 95%, 98%, 99%, 100% or any value therebetween. The voltage required for powering the electrically detachable single-component silicone-modified heat-conductive polyurethane hot melt adhesive is preferably 1-100 V, and specifically can be 1 V, 3 V, 5 V, 7 V, 9 V, 10 V, 20 V, 30 V, 40 V, 50 V, 60 V, 70 V, 80 V, 90 V, 100 V or any value therebetween; the time required for powering is preferably 1 s-60 min, such as 1 s, 2 s, 5 s, 15 s, 30 s, 40 s, 50 s, 1 min, 5 min, 10 min, 15 min, 20 min, 30 min, 40 min, 50 min, 60 min or any value therebetween. The content of isocyanate groups in the electrically detachable single-component silicone-modified heat-conductive polyurethane hot melt adhesive is 0.2-0.8%, and specifically can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% or any value therebetween.

[0013] The electrically detachable single-component silicone-modified heat-conductive polyurethane hot melt adhesive provided by the present application contains a silicone-modified polyurethane prepolymer and a modified filler composition, and optionally a catalyst and a water absorbent. The total content of the silicone-modified polyurethane prepolymer and the modified filler composition is preferably 90-99.8% based on the total weight of the electrically detachable single-component silicone-modified heat-conductive polyurethane hot melt adhesive, the content of the catalyst is preferably 0.1-5%, and the content of the water absorbent is preferably 0.1-5%. Specifically, the total content of the silicone-modified polyurethane prepolymer and the modified filler composition is preferably 90%, 92%, 94%, 96%, 98%, 99%, 99.5%, 99.8% or any value therebetween. The content of the catalyst and the water absorbent is preferably independently 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% or any value therebetween. The mass ratio of the silicone-modified polyurethane prepolymer to the modified filler composition is preferably 1:(1.5-7.5), and specifically can be 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5 or any value therebetween.

[0014] In the present application, the siloxane-modified polyurethane prepolymer can be commercially available or prepared according to various methods known in the art. In a preferred embodiment, the siloxane-modified polyurethane prepolymer is prepared by the following method: S11, first addition reaction of a polyol compound with a polyisocyanate compound, optionally in the presence of a catalyst, to obtain an isocyanate double-terminated polyurethane prepolymer; S12, second addition reaction of the isocyanate double-terminated polyurethane prepolymer with a monomercapto silane compound, to obtain the siloxane-modified polyurethane prepolymer.

[0015] In the preparation of the siloxane-modified polyurethane prepolymer, the molar ratio of the hydroxyl groups in the polyol compound, the isocyanate groups in the polyisocyanate compound, and the mercapto groups in the monomercapto silane compound is preferably 1:(2-2.5):(0.3-0.9). In this case, the siloxane-modified polyurethane prepolymer prepared has not only a low bubble content and good compatibility with the thermally conductive filler, which can provide good thermal conductivity, but also excellent adhesion and fast curing speed. Specifically, based on 1 mol of the hydroxyl groups in the polyol compound, the content of the isocyanate groups in the polyisocyanate compound is preferably 2.0-2.5 mol, such as 2.0 mol, 2.1 mol, 2.2 mol, 2.3 mol, 2.4 mol, 2.5 mol, or any value therebetween; and the content of the mercapto groups in the monomercapto silane compound is preferably 0.3-0.9 mol, such as 0.3 mol, 0.4 mol, 0.5 mol, 0.6 mol, 0.7 mol, 0.8 mol, 0.9 mol, or any value therebetween.

[0016] In the preparation of the siloxane-modified polyurethane prepolymer, the polyol compound can be any of the various polyol compounds commonly used in polyurethane production, such as at least one of a polyester polyol, a polyether polyol, a polycarbonate polyol, a polyalkylene polyol, etc. These polyol compounds can be used alone or in combination of two or more. The number average molecular weight of the polyol compound is preferably 1000-4000 g / mol, and can be specifically 1000, 1500, 2000, 2500, 3000, 3500, 4000 g / mol, or any value therebetween.

[0017] The polyester polyol can be a polyester polyol obtained by reacting a polycarboxylic acid with a polyhydric alcohol or a poly-ε-caprolactone polyol obtained by ring-opening polymerization of ε-caprolactone, etc. The polycarboxylic acid can include at least one of terephthalic acid, isophthalic acid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid, etc. The polyhydric alcohol can include at least one of ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, etc.

[0018] The polyether polyol can be selected from the group consisting of ring-opening polymers of ethylene glycol, propylene glycol, tetrahydrofuran, 3-methyltetrahydrofuran or be a random copolymer or a block copolymer of ethylene glycol, propylene glycol, tetrahydrofuran, 3-methyltetrahydrofuran or derivatives thereof or be a polyoxyalkylene modifier of bisphenol type. The polyoxyalkylene modifier of bisphenol type is a polyether polyol obtained by addition reaction of an alkylene oxide to the active hydrogen portion of the bisphenol type molecular skeleton and can be a random copolymer or a block copolymer. The alkylene oxide can be selected from at least one of ethylene oxide, propylene oxide, butylene oxide and isobutylene oxide.

[0019] The polycarbonate polyol can be selected from at least one of polycarbonate 1,6-hexanediol polyol, polycarbonate-1,4-butanediol-1,6-hexanediol diol, polycarbonate-1,5-pentanediol-1,6-hexanediol diol, polycaprolactone hexylene carbonate diol, polycarbonate-1,4-cyclohexanedimethanol-1,6-hexanediol diol, polyethylene carbonate diol, polypropylene carbonate diol, polybutylene carbonate diol, polyhexylene carbonate diol.

[0020] The polyalkylene polyol can be selected from at least one of polybutadiene polyol, hydrogenated polybutadiene polyol, hydrogenated polyisoprene polyol.

[0021] In the preparation of the above-mentioned silicone-modified polyurethane prepolymer, the polyisocyanate compound can be selected from at least one of isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, hydrogenated xylylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-pentane diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate, tetramethyl xylene diisocyanate, norbornane dimethylene isocyanate, lysine diisocyanate, triphenylmethane triisocyanate, thiophosphoric acid triphenyl isocyanate and 1,6,11-undecane triisocyanate.

[0022] In the preparation of the above-mentioned siloxane-modified polyurethane prepolymer, the monomercapto siloxane compound can be selected from at least one of 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, 3-mercaptopropyl methyl dimethoxysilane, and 3-mercaptopropyl methyl diethoxysilane.

[0023] In the preparation of the above-mentioned siloxane-modified polyurethane prepolymer, the conditions of the first addition reaction and the second addition reaction each independently include a temperature of preferably 70-90°C, such as 70°C, 75°C, 80°C, 85°C, 90°C, or any value therebetween; and a time of preferably 1-5h, such as 1h, 2h, 3h, 4h, 5h, or any value therebetween.

[0024] In the present application, the modified filler composition contains a thermally conductive filler, an electrolyte salt, and a silane coupling agent, and optionally a polar solvent compound. Among them, the content of the thermally conductive filler is preferably 70-85 parts by weight, such as 70, 72, 75, 78, 80, 82, 85 parts by weight, or any value therebetween; the content of the electrolyte salt is preferably 5-15 parts by weight, such as 5, 8, 10, 12, 15 parts by weight, or any value therebetween; the content of the silane coupling agent is preferably 2-7 parts by weight, such as 2, 3, 4, 5, 6, 7 parts by weight, or any value therebetween; and the content of the polar solvent compound is 0-15 parts by weight, such as 0, 1, 3, 5, 7, 9, 11, 13, 15 parts by weight, or any value therebetween.

[0025] In the present application, the thermally conductive filler is mainly inorganic, and the thermally conductive filler is first modified with an electrolyte salt and a silane coupling agent, and optionally a polar solvent compound. Among them, the siloxane in the silane coupling agent can modify the surface of the inorganic thermally conductive filler, the siloxane end of the silane coupling agent has good adhesion to the inorganic thermally conductive filler, and the organic functional groups such as mercapto, epoxy, isocyanate on the other end of the silane coupling agent have good compatibility with the organic polymer in the adhesive, and through the coupling effect, it can promote the subsequent mixing with the adhesive components and improve the compatibility. Among them, the modification of the thermally conductive filler before adding it into the adhesive has two effects, on the one hand, the silane coupling agent can be used to fully modify the surface of the inorganic thermally conductive filler; on the other hand, it also has the effect of removing the residual moisture in the components such as solvents, fillers, and electrolyte salts in the modified filler composition, avoiding the influence of moisture in the next step of mixing with the adhesive to cause side reactions. That is, the pre-mixing process can make the inorganic thermally conductive filler more fully modified and the water removed more thoroughly, thereby improving the compatibility of the thermally conductive filler with the adhesive. In addition, the polar solvent compound can act as a dispersion and mixing medium for the thermally conductive filler, the silane coupling agent, and the electrolyte salt.

[0026] The modified filler composition can be obtained by mixing the thermally conductive filler, the electrolyte salt, the silane coupling agent and the optional polar solvent compound in any manner. In a preferred embodiment, the modified filler composition is prepared by the following method: S21, vacuum stirring and dehydrating the electrolyte salt, the silane coupling agent and the optional polar solvent compound at 100-120℃ at a rotation speed of 100-200r / min for 1-5h to obtain a pretreated product; S22, vacuum stirring and reacting the pretreated product with the thermally conductive filler at 100-120℃ at a rotation speed of 100-200r / min for 3-6h to obtain the modified filler composition.

[0027] In the preparation process of the modified filler composition, in step S21, the temperature for vacuum stirring and dehydration is 100-120℃, such as 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, 112℃, 114℃, 116℃, 118℃, 120℃ or any value therebetween; the rotation speed is 100-200r / min, such as 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200r / min or any value therebetween; and the time is 1-5h, such as 1h, 2h, 3h, 4h, 5h or any value therebetween.

[0028] In the preparation process of the modified filler composition, in step S22, the temperature for vacuum stirring and reaction is 100-120℃, such as 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, 112℃, 114℃, 116℃, 118℃, 120℃ or any value therebetween; the rotation speed is 100-200r / min, such as 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200r / min or any value therebetween; and the time is 3-6h, such as 3h, 4h, 5h, 6h or any value therebetween.

[0029] In the present application, the thermally conductive filler can be at least one of alumina, magnesia, zinc oxide, nickel oxide, aluminum nitride, silicon nitride, boron nitride and silicon carbide. In addition, the particle size of the thermally conductive filler is preferably 1nm-100μm, such as 1nm, 50nm, 100nm, 500nm, 1μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm or any value therebetween.

[0030] In the present application, the electrolyte salt can be an alkali metal salt and / or an ionic liquid. Among them, the alkali metal salt can be a salt of an alkali metal cation and an organic acid anion or an inorganic acid anion or an organic sulfimide anion, and at least one of lithium triflate, lithium bistrifluoromethanesulfonimide, lithium chloride, lithium sulfate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium hexafluoroantimonate, sodium triflate, sodium bistrifluoromethanesulfonimide, sodium chloride, sodium sulfate, sodium tetrafluoroborate, sodium hexafluorophosphate, sodium hexafluoroantimonate, potassium triflate, potassium bistrifluoromethanesulfonimide, potassium chloride, potassium sulfate, potassium tetrafluoroborate, potassium hexafluorophosphate, and potassium hexafluoroantimonate can be cited. The ionic liquid is a molten salt in a liquid state at room temperature (25°C) and can be composed of an organic cation and an anion. Specific examples of the organic cation include, but are not limited to, imidazolium cations, pyrrolidinium cations, quaternary ammonium salt cations, quaternary phosphonium salt cations, pyrrolidinium cations, and piperidinium cations. Specific examples of the anion include, but are not limited to, triflate anions, tetrafluoroborate anions, hexafluorophosphate anions, bistrifluoromethanesulfonimide anions, hydrogen sulfate anions, ethyl sulfate anions, and p-toluenesulfonate anions. Specific examples of the ionic liquid can include, but are not limited to, at least one of 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium triflate, 1-ethyl-2,3-dimethylimidazolium triflate, 1-octyl-3-methylimidazolium triflate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-propyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-2,3-dimethylimidazolium tetrafluoroborate, 1-propyl-2,3-dimethylimidazolium tetrafluoroborate, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-2,3-dimethylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-diethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,2-dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide, 1-ethyl-2,3-dimethylimidazolium bisfluorosulfonimide, N-butylpyridinium tetrafluoroborate, hexyltriethylammonium bis(trifluoromethanesulfonyl)imide, methyltrioctylphosphonium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bisfluorosulfonimide, N-butyl-N-methylpyrrolidinium triflate, and N-propyl-N-methylpiperidinium bis(trifluoromethanesulfonyl)imide.

[0031] In the present application, specific examples of the silane coupling agent include, but are not limited to, at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane.

[0032] In the present application, the polar solvent compound can be selected from at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, dimethoxy methane, 1,3-dimethoxypropane, 1,3-dioxolane, ethoxymethoxyethane, poly(ethylene glycol)dimethyl ether, poly(ethylene glycol)methyl ether methacrylate, poly(ethylene glycol)methyl ether, poly(ethylene glycol)methyl ether acrylate, poly(ethylene glycol)diglycidyl ether, poly(ethylene glycol)ethyl ether methacrylate, poly(ethylene glycol)-bis(2-ethylhexanoate), poly(ethylene glycol)octyl ether, poly(ethylene glycol)phenyl ether acrylate, poly(ethylene glycol)tetrahydrofurfuryl ether, poly(ethylene glycol)methyl ether tosylate.

[0033] In the present application, the catalyst can be exemplified by at least one of dibutyltin dilaurate, stannous octoate, zinc isooctoate, bismuth isooctoate, triethylamine, diethylenetriamine, triethylenediamine, N-ethylmorpholine, 2,2-dimorpholinodiethylether.

[0034] In the present application, the water absorbing agent can be exemplified by at least one of molecular sieve desiccant, oxazolidine water scavenger, p-toluenesulfonylisocyanate, and triethyl orthoformate.

[0035] The present application provides a preparation method of the electrically detachable one-component siloxane-modified thermally conductive polyurethane hot melt adhesive, which comprises uniformly mixing a siloxane-modified polyurethane prepolymer and a modified filler composition, and optionally a catalyst and a water absorbing agent, to obtain the electrically detachable one-component siloxane-modified thermally conductive polyurethane hot melt adhesive.

[0036] The mixing method is not particularly limited, and the materials can be mixed in any order. In a preferred embodiment, the mixing step comprises:

[0037] S31, polyol compound and optional water absorption agent are vacuum stirred at 100-120℃ and 100-200r / min for 1-5h, then cooled to 70-90℃ to obtain a pretreated product;

[0038] S32, polyisocyanate compound and optional catalyst are added to the pretreated product, and vacuum stirring is carried out at 70-90℃ and 100-200r / min for 1-5h to obtain an isocyanate double-terminated polyurethane prepolymer;

[0039] S33, the isocyanate double-terminated polyurethane prepolymer and monomercaptosilane compound are vacuum stirred at 70-90℃ and 100-200r / min for 1-5h to obtain a siloxane modified polyurethane prepolymer;

[0040] S34, the siloxane modified polyurethane prepolymer and modified filler composition are vacuum stirred at 70-90℃ and 100-200r / min for 0.5-2h to obtain an electrically detachable one-component siloxane modified thermal conductive polyurethane hot melt adhesive.

[0041] In the preparation process of the above electrically detachable one-component siloxane modified thermal conductive polyurethane hot melt adhesive, in step S31, the temperature of vacuum stirring dehydration is 100-120℃, such as 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, 112℃, 114℃, 116℃, 118℃, 120℃ or any value between them; the rotation speed is 100-200r / min, such as 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200r / min or any value between them; the time is 1-5h, such as 1h, 2h, 3h, 4h, 5h or any value between them.

[0042] In the preparation process of the above electrically detachable one-component siloxane modified thermal conductive polyurethane hot melt adhesive, in step S32, the temperature of vacuum stirring reaction is 70-90℃, such as 70℃, 72℃, 75℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃, 90℃ or any value between them; the rotation speed is 100-200r / min, such as 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200r / min or any value between them; the time is 1-5h, such as 1h, 2h, 3h, 4h, 5h or any value between them.

[0043] In the preparation process of the electrically detachable one-component silicone-modified heat-conducting polyurethane hot melt adhesive, in step S33, the temperature of the vacuum stirring reaction is 70-90℃, such as 70℃, 72℃, 75℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃, 90℃ or any value between them; the rotating speed is 100-200 r / min, such as 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 r / min or any value between them; and the time is 1-5 h, such as 1 h, 2 h, 3 h, 4 h, 5 h or any value between them.

[0044] In the preparation process of the electrically detachable one-component silicone-modified heat-conducting polyurethane hot melt adhesive, in step S34, the temperature of the vacuum stirring reaction is 70-90℃, such as 70℃, 72℃, 75℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃, 90℃ or any value between them; the rotating speed is 100-200 r / min, such as 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 r / min or any value between them; and the time is 0.5-2 h, such as 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h or any value between them.

[0045] The application further provides the use of the electrically detachable one-component silicone-modified heat-conducting polyurethane hot melt adhesive in the bonding of electronic products.

[0046] The application will be described in detail below through examples.

[0047] The electrically detachable one-component silicone-modified heat-conducting polyurethane hot melt adhesive provided by the application is suitable for bonding substrates with electric conductivity.

[0048] The application will be described in detail below through examples and comparative examples.

[0049] In the following examples and comparative examples, the parts of each raw material refer to weight parts.

[0050] Preparation Example 1 modified filler composition

[0051] According to parts by weight, 9.88 parts of 1-propyl-3-methylimidazole tetrafluoroborate, 6.17 parts of propylene carbonate, 3.70 parts of 3-aminopropyltrimethoxysilane were added to the reaction kettle, heated to 110°C, vacuum dehydration for 2h under the condition of 150r / min stirring, 40.25 parts of alumina with particle size of 8-10μm (Foshan Weikede material, GTC-21K), 40.0 parts of magnesium oxide with particle size of 30-50nm (Hangzhou Hengna New Material, HN-Mg50D) were added to the reaction kettle, vacuum dehydration for 4h under the condition of 110°C, 150r / min stirring and mixing, to obtain modified filler composition A-1, which was vacuum sealed and stored for standby.

[0052] Modified filler composition of preparation example 2

[0053] According to parts by weight, 11.90 parts of 1-propyl-3-methylimidazole bis(trifluoromethanesulfonyl) imide salt, 4.0 parts of 3-epoxypropoxypropyltrimethoxysilane were added to the reaction kettle, heated to 110°C, vacuum dehydration for 2h under the condition of 150r / min stirring, 63.33 parts of alumina with particle size of 6-9μm (Foshan Weikede material, GTC-31K), 20.0 parts of boron nitride with particle size of 60-75μm (Shanghai Bitu, GBN-60) were added to the reaction kettle, vacuum dehydration for 4h under the condition of 110°C, 150r / min stirring and mixing, to obtain modified filler composition A-2, which was vacuum sealed and stored for standby.

[0054] Modified filler composition of preparation example 3

[0055] According to parts by weight, 7.69 parts of hexyltriethylammonium bis(trifluoromethanesulfonyl) imide salt, 4.62 parts of poly(ethylene glycol) diglycidyl ether, 3.08 parts of vinyltrimethoxysilane were added to the reaction kettle, heated to 110°C, vacuum dehydration for 2h under the condition of 150r / min stirring, 34.32 parts of alumina with particle size of 8-10μm (Foshan Weikede material, GTC-066B), 50.30 parts of alumina with particle size of 2.5-4.0μm (Foshan Weikede material, DR-50) were added to the reaction kettle, vacuum dehydration for 4h under the condition of 110°C, 150r / min stirring and mixing, to obtain modified filler composition A-3, which was vacuum sealed and stored for standby.

[0056] Modified filler composition of preparation example 4

[0057] By weight parts, 6.82 parts of lithium bistrifluoromethanesulfonimide, 11.36 parts of ethylene carbonate, 5.68 parts of 3-isocyanate propyl trimethoxysilane were added to the reaction kettle, heated to 110°C, vacuum dehydration for 2h under the condition of 150r / min stirring, 33.12 parts of magnesium oxide with particle size of 30-50nm (Hangzhou Hengna New Material, HN-Mg50D), 43.02 parts of alumina with particle size of 8-10μm (Foshan Weikede Material, GTC-066B) were added to the reaction kettle, vacuum dehydration for 4h under the condition of 110°C, 150r / min stirring and mixing, to obtain modified filler composition A-4, which was vacuum sealed and stored for later use.

[0058] Modified filler composition of preparation example 5

[0059] By weight parts, 8.86 parts of lithium tetrafluoroborate, 10.13 parts of polyethylene glycol-bis(2-ethylhexanoate), 5.06 parts of 3-mercapto propyl trimethoxysilane were added to the reaction kettle, heated to 110°C, vacuum dehydration for 2h under the condition of 150r / min stirring, 60.53 parts of alumina with particle size of 8-10μm (Foshan Weikede Material, GTC-21K), 15.42 parts of boron nitride with particle size of 60-75μm (Shanghai Bitu, GBN-60) were added to the reaction kettle, vacuum dehydration for 4h under the condition of 110°C, 150r / min stirring and mixing, to obtain modified filler composition A-5, which was vacuum sealed and stored for later use.

[0060] Modified filler composition of comparative preparation example 1

[0061] The modified filler composition was prepared in the manner of preparation example 3, except that the hexyl triethylammonium bis(trifluoromethanesulfonyl) imide salt in preparation example 3 was removed, as follows:

[0062] By weight parts, 4.62 parts of poly(ethylene glycol) diglycidyl ether, 3.08 parts of vinyl trimethoxysilane were added to the reaction kettle, heated to 110°C, vacuum dehydration for 2h under the condition of 150r / min stirring, 34.32 parts of alumina with particle size of 8-10μm (Foshan Weikede Material, GTC-066B), 50.30 parts of alumina with particle size of 2.5-4.0μm (Foshan Weikede Material, DR-50) were added to the reaction kettle, vacuum dehydration for 4h under the condition of 110°C, 150r / min stirring and mixing, to obtain modified filler composition C-1, which was vacuum sealed and stored for later use.

[0063] Modified filler composition of comparative preparation example 2

[0064] The modified filler composition was prepared in the manner of preparation example 1, except that the 3-aminopropyl trimethoxysilane in preparation example 1 was removed, as follows:

[0065] 9.88 parts of 1-propyl-3-methylimidazole tetrafluoroborate and 6.17 parts of propylene carbonate were added into a reaction kettle, heated to 110°C, vacuum dehydration for 2h under the condition of stirring at 150r / min, 40.25 parts of alumina with particle size of 8-10μm (Foshan Weikede Material, GTC-21K) and 40.0 parts of magnesium oxide with particle size of 30-50nm (Hangzhou Hengna New Material, HN-Mg50D) were added into the reaction kettle, vacuum dehydration for 4h under the condition of stirring at 110°C and 150r / min to obtain modified filler composition C-2, which was vacuum sealed and stored for later use.

[0066] Example 1

[0067] 4.88g (9.763mmol) of polyhexanediol adipate diol with number average molecular weight of 1000, 4.88g (9.763mmol) of polyoxypropylene ether diol with number average molecular weight of 1000, 0.5g of water absorption agent Additive TI were added into a reaction kettle, heated to 110°C, vacuum dehydration for 2h under the condition of stirring at 150r / min; then cooled to 80°C, 5.86g (46.863mmol) of 4,4'-diphenyl methane diisocyanate (MDI), 0.2g of stannous octoate were added, reacted for 2h under the condition of stirring at 150r / min, 2.68g (13.668mmol) of 3-mercaptopropyl trimethylsilane was added, reacted for 2h under the condition of vacuum stirring at 80°C and 150r / min, then 81.0g of modified filler composition A1 was added, mixed for 1h under the condition of vacuum stirring at 80°C and 150r / min, then discharged to obtain electrically detachable one-component silicone modified thermally conductive polyurethane hot melt adhesive, in which the content of isocyanate group was 0.57%, which was vacuum sealed and stored.

[0068] Example 2

[0069] By weight, 4.09 g (8.185 mmol) of polybutylene adipate diol with a number average molecular weight of 1000, 4.09 g (8.185 mmol) of polytetramethylene ether glycol with a number average molecular weight of 1000, 0.2 g of water absorption agent Additive OF, were heated to 110°C, vacuum dehydrated for 2h under the condition of stirring at 150r / min; then cooled to 80°C, 5.36 g (40.927 mmol) of 4,4-diisocyanate dicyclohexyl methane (HMDI), 0.5 g of dibutyl tin dilaurate were added, and reacted for 2h under the condition of stirring at 150r / min, 1.75 g (7.367 mmol) of 3-mercaptopropyl triethoxysilane was added, and after vacuum stirring at 80°C and 150r / min for 2h, 84.0 g of modified filler composition A2 was added, and after mixing at 80°C, 150r / min under vacuum for 1h, the product was discharged to obtain an electrically detachable one-component silicone modified thermally conductive polyurethane hot melt adhesive, wherein the content of isocyanate group is 0.72%, and the product was vacuum sealed and stored.

[0070] Example 3

[0071] By weight, 14.27 g (4.758 mmol) of polytetramethylene ether glycol with a number average molecular weight of 3000, 14.27 g (4.758 mmol) of polycaprolactone diol with a number average molecular weight of 2000, 0.6 g of water absorption agent Siliporite SA1702, were heated to 110°C, vacuum dehydrated for 2h under the condition of stirring at 150r / min; then cooled to 80°C, 3.52 g (20.936 mmol) of hexamethylene diisocyanate (HDI), 1.1 g of 2,2-dimorpholinyl diethyl ether were added, and reacted for 2h under the condition of stirring at 150r / min, 1.23 g (6.852 mmol) of 3-mercaptopropyl methyl dimethoxysilane was added, and after vacuum stirring at 80°C and 150r / min for 2h, 65.0 g of modified filler composition A3 was added, and after mixing at 80°C, 150r / min under vacuum for 1h, the product was discharged to obtain an electrically detachable one-component silicone modified thermally conductive polyurethane hot melt adhesive, wherein the content of isocyanate group is 0.67%, and the product was vacuum sealed and stored.

[0072] Example 4

[0073] By weight, 3.09 g (3.086 mmol) of polycarbonate 1,6 hexanediol diol with a number average molecular weight of 1000, 3.09 g (3.086 mmol) of polybutylene adipate diol with a number average molecular weight of 1000, 0.2 g of water absorption agent Additive TI, heated to 110°C, vacuum dehydration for 2h under the condition of stirring at 150r / min; then cooled to 80°C, 2.74 g (12.345 mmol) of isophorone diisocyanate (IPDI), 1.3 g of zinc isooctoate were added, and reacted for 2h under the condition of stirring at 150r / min, 1.59 g (6.667 mmol) of 3-mercaptopropyl triethoxysilane was added, and after vacuum stirring at 80°C and 150r / min for 2h, 88.0 g of modified filler composition A4 was added, and after mixing at 80°C, 150r / min under vacuum for 1h, the product was discharged to obtain an electrically detachable one-component silicone modified thermally conductive polyurethane hot melt adhesive, wherein the content of isocyanate group is 0.24%, and the product was vacuum sealed for storage.

[0074] Example 5

[0075] By weight, 7.57 g (3.783 mmol) of polybutylene succinate diol with a number average molecular weight of 2000, 7.57 g (3.783 mmol) of polycaprolactone diol with a number average molecular weight of 2000, 0.4 g of water absorption agent Additive OF, heated to 110°C, vacuum dehydration for 2h under the condition of stirring at 150r / min; then cooled to 80°C, 3.78 g (15.134 mmol) of 4,4'-diphenyl methane diisocyanate (MDI), 0.2 g of bismuth isooctoate were added, and reacted for 2h under the condition of stirring at 150r / min, 1.48 g (7.567 mmol) of 3-mercaptopropyl trimethylsilane was added, and after vacuum stirring at 80°C and 150r / min for 2h, 79.0 g of modified filler composition A5 was added, and after mixing at 80°C, 150r / min under vacuum for 1h, the product was discharged to obtain an electrically detachable one-component silicone modified thermally conductive polyurethane hot melt adhesive, wherein the content of isocyanate group is 0.32%, and the product was vacuum sealed for storage.

[0076] Comparative Example 1

[0077] By weight, 29.2 g (14.6 mmol) of polyoxypropylene ether diol with a number average molecular weight of 2000, 29.2 g (14.6 mmol) of polyhexanediol adipate with a number average molecular weight of 2000, 8.0 g of lithium trifluoromethanesulfonate, 8.0 g of propylene carbonate, 10.0 g of acrylic resin BR113, 0.5 g of water-absorbing agent Additive OF, and 0.5 g of other ingredients were added. 3-Aminopropyltrimethoxysilane was heated to 110°C and vacuum dehydrated for 2 hours under stirring at 150 r / min. Then, it was cooled to 80°C, and 14.6 g (58.4 mmol) of 4,4'-diphenylmethane diisocyanate (MDI) and 0.2 g of dibutyltin dilaurate were added. The mixture was reacted for 2 hours under stirring at 150 r / min and then discharged to obtain a reference electrically detachable one-component siloxane-modified thermally conductive polyurethane hot melt adhesive, wherein the isocyanate group content was 2.45%, and it was stored under vacuum sealing.

[0078] Comparative Example 2

[0079] The electrically detachable one-component siloxane-modified thermally conductive polyurethane hot melt adhesive was prepared according to the method described in Example 3, except that the electrolyte salt in Example 3 was removed, as detailed below:

[0080] By weight, 14.27 g (4.758 mmol) of polytetrahydrofuran ether glycol with a number average molecular weight of 3000, 14.27 g (4.758 mmol) of polycaprolactone glycol with a number average molecular weight of 2000, and 0.6 g of water-absorbing agent Siliporite SA1702 were heated to 110 °C and vacuum dehydrated for 2 h under stirring at 150 r / min; then cooled to 80 °C, and 3.52 g (20.936 mmol) of hexamethylene diisocyanate (HDI) and 1.1 g of... 2,2-Dimorpholinodiethyl ether was reacted at 150 r / min for 2 h with stirring. 1.23 g (6.852 mmol) of 3-mercaptopropylmethyldimethoxysilane was added, and the mixture was stirred under vacuum at 80 °C and 150 r / min for 2 h. Then, 65.0 g of modified filler composition C1 was added, and the mixture was stirred under vacuum at 80 °C and 150 r / min for 1 h before being discharged to obtain a reference single-component siloxane-modified thermally conductive polyurethane hot melt adhesive with an isocyanate group content of 0.67%. The adhesive was stored under vacuum sealing.

[0081] Comparative Example 3

[0082] The electrically detachable one-component siloxane-modified thermally conductive polyurethane hot melt adhesive was prepared according to the method described in Example 3, except that the components of the modified filler composition from Example 3 were directly added to the adhesive system, as detailed below:

[0083] The 14.27 g (4.758 mmol) of polytetrahydrofuran ether diol with a number average molecular weight of 3000, 14.27 g (4.758 mmol) of polycaprolactone diol with a number average molecular weight of 2000, and 0.6 g of water absorption agent Siliporite SA1702 were heated to 110°C, vacuum dehydrated for 2 h under the condition of stirring at 150 r / min, then cooled to 80°C, 3.52 g (20.936 mmol) of hexamethylene diisocyanate (HDI) and 1.1 g of 2,2-dimorpholinyl diethyl ether were added, and reacted for 2 h under the condition of stirring at 150 r / min, 1.23 g (6.852 mmol) of 3-mercaptopropyl methyl dimethoxy silane was added, and after vacuum stirring at 80°C and 150 r / min for 2 h, 5.0 g of hexyl triethyl ammonium bis(trifluoromethane sulfonate) imide salt, 3.0 g of poly(ethylene glycol) diglycidyl ether, and 2.0 g of vinyl trimethoxy silane were added to the reaction kettle, heated to 110°C, vacuum dehydrated for 2 h under the condition of stirring at 150 r / min, 22.31 g of alumina with a particle size of 8-10 μm (Foshan Weikede Material, GTC-066B) and 32.69 g of alumina with a particle size of 2.5-4.0 μm (Foshan Weikede Material, DR-50) were mixed under the condition of vacuum stirring at 80°C and 150 r / min for 1 h, and then discharged to obtain a reference single-component siloxane modified thermally conductive polyurethane hot melt adhesive, wherein the content of isocyanate groups was 0.67%, and the vacuum sealed preservation was performed.

[0084] Comparative Example 4

[0085] The electrically detachable single-component siloxane modified thermally conductive polyurethane hot melt adhesive was prepared in the same manner as in Example 1, except that the proportion of the mercapto siloxane component in the siloxane end-capping modified prepolymer was reduced so that the content of isocyanate groups in the obtained electrically detachable single-component siloxane modified thermally conductive polyurethane hot melt adhesive exceeded 0.8%, and the details were as follows:

[0086] By weight, 5.62 g (11.245 mmol) of polyhexanediol adipate diol with a number average molecular weight of 1000, 5.62 g (11.245 mmol) of polyoxypropylene ether diol with a number average molecular weight of 1000, 0.5 g of water absorption agent Additive TI, were heated to 110°C, vacuum dehydrated for 2 h under the condition of stirring at 150 r / min; then cooled to 80°C, 6.75 g (53.974 mmol) of 4,4'-diphenyl methane diisocyanate (MDI), 0.2 g of stannous octoate were added, and reacted for 2 h under the condition of stirring at 150 r / min, 0.31 g (1.574 mmol) of 3-mercaptopropyl trimethyl silane was added, and after vacuum stirring at 80°C and 150 r / min for 2 h, 81.0 g of modified filler composition A1 was added, and after mixing at 80°C, 150 r / min under vacuum for 1 h, the product was discharged to obtain a reference electrically dismountable one-component siloxane modified thermal conductive polyurethane hot melt adhesive, wherein the content of isocyanate group was 1.26%, and the product was vacuum sealed and stored.

[0087] Comparative Example 5

[0088] The electrically dismountable one-component siloxane modified thermal conductive polyurethane hot melt adhesive was prepared in the manner of Example 1, except that 3- aminopropyl trimethoxysilane in Example 1 was removed, and the specific process was as follows:

[0089] By weight, 4.88 g (9.763 mmol) of polyhexanediol adipate diol with a number average molecular weight of 1000, 4.88 g (9.763 mmol) of polyoxypropylene ether diol with a number average molecular weight of 1000, 0.5 g of water absorption agent Additive TI, were heated to 110°C, vacuum dehydrated for 2 h under the condition of stirring at 150 r / min; then cooled to 80°C, 5.86 g (46.863 mmol) of 4,4'-diphenyl methane diisocyanate (MDI), 0.2 g of stannous octoate were added, and reacted for 2 h under the condition of stirring at 150 r / min, 2.68 g (13.668 mmol) of 3-mercaptopropyl trimethyl silane was added, and after vacuum stirring at 80°C and 150 r / min for 2 h, 81.0 g of modified filler composition C2 was added, and after mixing at 80°C, 150 r / min under vacuum for 1 h, the product was discharged to obtain a reference electrically dismountable one-component siloxane modified thermal conductive polyurethane hot melt adhesive, wherein the content of isocyanate group was 0.57%, and the product was vacuum sealed and stored.

[0090] Test Example

[0091] (1) Solidification bubble performance: The electrically detachable single-component silicone-modified thermally conductive polyurethane hot melt adhesive obtained in the examples and comparative examples was melted at 110°C, and after melting was completed, a 400-μm doctor blade was used to coat a film on a release film. The film was placed in a 25°C, 50 RH% oven for 4h and then the appearance of the film was observed. Whether bubbles were generated on the film was recorded. The results are shown in Table 1.

[0092] (2) Bonding strength at different curing times (1h, 1d, 7d): The electrically detachable single-component silicone-modified thermally conductive polyurethane hot melt adhesive obtained in the examples and comparative examples was dispensed at 110°C using a dispenser, and a 25mm*4mm rectangular glue line was coated on a stainless steel substrate. Then, another stainless steel substrate was attached to the stainless steel substrate. After attachment, the sample was cured in a 25°C, 50% RH environment for 1h, 1d, and 7d. Then, the bonding sample was run at a speed of 10mm / min until the sample was bonded to fail along the shear direction using a universal material testing machine. The maximum force value displayed by the instrument was recorded, and the shear bonding strength of the stainless steel substrate after the adhesive was cured for different times was calculated in combination with the bonding area. The results are shown in Table 1.

[0093] (3) Bonding strength after power on: The electrically detachable single-component silicone-modified thermally conductive polyurethane hot melt adhesive obtained in the examples and comparative examples was dispensed at 110°C using a dispenser, and a 25mm*4mm rectangular glue line was coated on a stainless steel substrate. Then, another stainless steel substrate was attached to the stainless steel substrate. After attachment, the sample was cured in a 25°C, 50% RH environment for 48h. Then, the positive and negative leads of a direct current power supply were clamped at both ends of the shear sample, and a certain voltage was applied for a certain time. After power on, the shear sample was removed, and the bonding sample was run at a speed of 10mm / min until the sample was bonded to fail along the shear direction using a universal material testing machine. The maximum force value displayed by the instrument was recorded, and the shear bonding strength of the stainless steel substrate after power on was calculated in combination with the bonding area. The results are shown in Table 1.

[0094] (4) Thermal conductivity: The electrically detachable single-component silicone-modified thermally conductive polyurethane hot melt adhesive obtained in the examples and comparative examples was coated on a clean PET film and cured in a 25°C, 50% RH environment for 7d. Then, the thermal conductivity was tested according to the method of national standard GB / T11205-2009.

[0095] Table 1

[0096]

[0097] As can be seen from the results in Table 1, the electrically detachable single-component silicone-modified heat-conductive polyurethane hot melt adhesive provided by the present application is free of bubbles and has a high thermal conductivity, which is beneficial to faster heat transfer of the adhesive, thereby helping the bonded parts to achieve the function of rapid heat dissipation and reducing the influence of rapid heat increase on the operability and safety of the electronic parts. According to practical experience, an adhesive with a bonding strength of 2.0 MPa or less at room temperature is detachable, and otherwise it is not. As can be seen from the results in Table 1, the electrically detachable single-component silicone-modified heat-conductive polyurethane hot melt adhesive provided by the present application can obviously attenuate the bonding strength after being electrified, and can even directly fall off, thus having excellent electrically detachable performance.

[0098] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those of ordinary skill in the art can make changes, modifications, replacements and variations to the above embodiments without departing from the principles and spirit of the present application within the scope of the present application.

Claims

1. An electrically dismountable one-component silicone-modified thermally conductive polyurethane hot melt adhesive, characterized in that, The electrically detachable single-component siloxane modified heat-conductive polyurethane hot melt adhesive contains a siloxane modified polyurethane prepolymer and a modified filler composition obtained by mixing a heat-conductive filler, an electrolyte salt and a silane coupling agent and optionally a polar solvent compound, and optionally a catalyst and a water absorbent, the content of isocyanate groups in the electrically detachable single-component siloxane modified heat-conductive polyurethane hot melt adhesive is 0.2-0.8%, the mass ratio of the siloxane modified polyurethane prepolymer to the modified filler composition is 1:(1.5-7.5), and the bonding strength attenuation of the electrically detachable single-component siloxane modified heat-conductive polyurethane hot melt adhesive after being electrified under a voltage of 1-100 V is more than 80%. The siloxane modified polyurethane prepolymer is prepared by the following method: S11, a first addition reaction of a polyol compound and a polyisocyanate compound, optionally in the presence of a catalyst, is carried out to obtain an isocyanate double-terminated polyurethane prepolymer; S12, a second addition reaction of the isocyanate double-terminated polyurethane prepolymer and a monomercapto siloxane compound is carried out to obtain a siloxane modified polyurethane prepolymer.

2. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive according to claim 1, characterized in that, The total content of the siloxane modified polyurethane prepolymer and the modified filler composition is 90-99.8%, the content of the catalyst is 0.1-5%, and the content of the water absorbent is 0.1-5%, based on the total weight of the electrically detachable single-component siloxane modified heat-conductive polyurethane hot melt adhesive.

3. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive according to claim 1, characterized in that, The molar ratio of hydroxyl groups in the polyol compound, isocyanate groups in the polyisocyanate compound and mercapto groups in the monomercapto siloxane compound is 1:(2-2.5):(0.3-0.9).

4. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 1, wherein, The polyol compound is at least one selected from polyester polyol, polyether polyol and polycarbonate polyol.

5. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 1, wherein, The polyisocyanate compound is at least one selected from isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, hydrogenated xylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-pentane diisocyanate, 1,4-phenylene diisocyanate, xylene diisocyanate, tetramethyl xylene diisocyanate, norbornane dimethylene isocyanate, lysine diisocyanate, triphenylmethane triisocyanate, thiophosphoric acid triphenyl isocyanate and 1,6,11-undecane triisocyanate.

6. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 1, wherein, The monomercapto siloxane compound is at least one selected from 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, 3-mercaptopropyl methyl dimethoxysilane and 3-mercaptopropyl methyl diethoxysilane.

7. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 1, wherein, The modified filler composition is prepared by the following method: S21, the electrolyte salt, the silane coupling agent and optionally the polar solvent compound are vacuum stirred at 100-120°C at a rotation speed of 100-200 r / min for 1-5 h to obtain a pretreated product; S22, vacuum stirring the pretreatment product with the thermally conductive filler at 100-120℃ and at a rotation speed of 100-200r / min for 3-6h to obtain the modified filler composition.

8. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive according to claim 7, characterized in that, The content of the thermally conductive filler in the modified filler composition is 70-85 parts by weight, the content of the electrolyte salt is 5-15 parts by weight, the content of the silane coupling agent is 2-7 parts by weight, and the content of the polar solvent compound is 0-15 parts by weight.

9. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 7, wherein, The thermally conductive filler is selected from at least one of alumina, magnesia, zinc oxide, nickel oxide, aluminum nitride, silicon nitride, boron nitride, and silicon carbide.

10. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 7, wherein, The electrolyte salt is an alkali metal salt and / or an ionic liquid.

11. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 7, wherein, The silane coupling agent is selected from at least one of 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, 3-mercaptopropyl methyl dimethoxysilane, 3-mercaptopropyl methyl diethoxysilane, 3-epoxypropoxypropyl trimethoxysilane, 3-epoxypropoxypropyl triethoxysilane, 3-epoxypropoxypropyl methyl dimethoxysilane, 3-epoxypropoxypropyl methyl diethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-epoxypropoxypropyl methyl diethoxysilane, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-(2-aminoethyl) aminopropyl trimethoxysilane, 3-(2-aminoethyl) aminopropyl triethoxysilane, 3-(2-aminoethyl) aminopropyl methyl dimethoxysilane, 3-(meth) acryloyloxypropyl trimethoxysilane, 3-(meth) acryloyloxypropyl triethoxysilane, 3-(meth) acryloyloxypropyl methyl dimethoxysilane, 3-(meth) acryloyloxypropyl methyl diethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, and 3-isocyanate propyl trimethoxysilane.

12. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 7, wherein, The polar solvent compound is selected from at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxy methane, 1,3-dimethoxypropane, 1,3-dioxolane, ethoxymethoxyethane, polyethylene glycol dimethyl ether, polyethylene glycol methyl ether methacrylate, polyethylene glycol methyl ether, polyethylene glycol methyl ether acrylate, polyethylene glycol diglycidyl ether, polyethylene glycol ethyl ether methacrylate, polyethylene glycol-bis-2-ethylhexanoate, polyethylene glycol octyl ether, polyethylene glycol phenyl ether acrylate, polyethylene glycol tetrahydrofurfuryl ether, polyethylene glycol methyl ether toluenesulfonate.

13. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 1, wherein, The catalyst is selected from at least one of dibutyl tin dilaurate, stannous octoate, zinc isooctoate, bismuth isooctoate, triethylamine, diethylenetriamine, triethylenediamine, N-ethylmorpholine, and 2,2-dimorpholinodiethyl ether.

14. The electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 1, wherein, The water absorbing agent is selected from at least one of molecular sieve desiccant, oxazolidine water scavenger, p-methylbenzenesulfonylisocyanate, and triethyl orthoformate.

15. The process for preparing the electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive according to any one of claims 1 to 14, characterized in that, The method comprises uniformly mixing the siloxane modified polyurethane prepolymer and the modified filler composition, and optionally the catalyst and the water absorbing agent, to obtain the electrically detachable one-component siloxane modified thermally conductive polyurethane hot melt adhesive.

16. The process for preparing the electrically detachable one-component silicone-modified thermally conductive polyurethane hot melt adhesive of claim 15, characterized in that, The mixing step comprises: S31, vacuum stirring and dehydrating the polyhydric alcohol compound and optional water absorbent at 100-120℃ and 100-200r / min for 1-5h, then cooling to 70-90℃ to obtain a pretreated product; S32, adding the polyisocyanate compound and optional catalyst to the pretreated product, vacuum stirring and reacting at 70-90℃ and 100-200r / min for 1-5h to obtain an isocyanate double-terminated polyurethane prepolymer; S33, vacuum stirring and reacting the isocyanate double-terminated polyurethane prepolymer and monomercaptosiloxane compound at 70-90℃ and 100-200r / min for 1-5h to obtain a siloxane modified polyurethane prepolymer; S34, vacuum stirring and reacting the siloxane modified polyurethane prepolymer and modified filler composition at 70-90℃ and 100-200r / min for 0.5-2h to obtain the electrically detachable one-component siloxane modified heat-conductive polyurethane hot melt adhesive.

17. Application of the electrically detachable one-component siloxane modified heat-conductive polyurethane hot melt adhesive of any one of claims 1-14 in bonding electronic products.

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