Self-adhesive single-component liquid silicone rubber with low compression set and preparation method thereof

Abstract

The invention discloses self-adhesive single-component liquid silicone rubber with low compression set and a preparation method thereof. The preparation method comprises the following steps: kneading high-viscosity double-end vinyl polydimethylsiloxane, white carbon black, hexamethyldisilazane and water to prepare base rubber; and uniformly mixing and stirring the base rubber with double-end vinyl polydimethylsiloxane, polydimethylmethylvinylsiloxane, polydimethylmethylhydrosiloxane, a first functional aid, a second functional aid, an inhibitor and a catalyst in proportion to prepare the single-component liquid silicone rubber. The silicone rubber has excellent bonding performance on various substrates such as stainless steel, aluminum materials, copper materials, kovar alloys, nylon, polycarbonate and PBT (polybutylene terephthalate), has excellent mechanical properties and low compression set rate, is suitable for sealing and bonding of various automobile, industrial and electronic components, and has wide application prospects. The present invention relates to a sealing strip, in particular to a sealing adhesive scenario for in-situ curing sealing gasket (CIPG) applications, instead of a conventional sealing strip.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon materials, specifically relating to a self-adhesive single-component liquid silicone rubber with low compression set and its preparation method. Background Technology

[0002] Organosilicon materials, with their excellent high and low temperature resistance, weather resistance, high elasticity over a wide temperature range, and electrical insulation properties, have been widely used in various sectors of the national economy. With the rapid development of the new energy industry, airtightness and precision are crucial factors in the design and manufacturing of new energy electric vehicles, especially in harsh environments such as high pressure, high temperature, and high humidity. CIPG (Cured-In-Place Gasket) technology provides the best sealing solution for new energy vehicle batteries, BMS battery management systems, electronic control units, and OBC modules. It is a method of directly applying liquid silicone rubber to the surface of components, and after the silicone rubber cures by heating, achieving sealing protection through mechanical locking (i.e., compression). This process can directly replace traditional pre-formed gaskets, reducing labor costs. Based on the sealing stroke design, automated dispensing equipment can achieve precise positioning and quickly adapt to system changes, exhibiting good complexity and positioning accuracy. It avoids deviations caused by manual installation, greatly improving the product qualification rate. It has advantages such as low cost, good sealing performance, and high production efficiency. The liquid silicone rubber is required to have properties such as adhesion, resistance to high and low temperatures, resistance to high humidity, and resistance to high pressure compression.

[0003] Existing patent document CN116904161A discloses a self-adhesive silicone rubber with low compression set and its preparation method. It uses nano-calcium carbonate, nano-organic montmorillonite, fused silica powder and other materials as reinforcing fillers, and titanium dioxide, cerium oxide, zinc carbonate and zinc oxide as functional additives. Although the introduction of these heavy fillers can improve the tensile strength of the material and reduce the compression set, it will significantly reduce the elongation at break (the elongation at break of the material is <200%) and increase the density of the material. Patent document CN115386333A discloses a low compression set one-component thermosetting silicone sealant and its preparation method. It uses vinyl MQ silicone resin in combination with cyclic or chain siloxane tackifiers, and platinum-alkynyl group complexes and long-chain alkynols or phenylalkynols in combination to obtain a one-component thermosetting silicone sealant with a long shelf life. When tetraisooctyl titanate and other titanates are added to the adhesive as tackifiers in this patent, the titanates have poor stability and are easily hydrolyzed, thus losing their activity. In addition, there may be a side reaction in which titanates catalyze the dehydrogenation condensation of hydrogen-containing silicone oil and residual silanols in the system.

[0004] Addition-cured liquid silicone rubber exhibits weak adhesion to many substrates (such as stainless steel, aluminum, and plastics), and its resilience after compression at high temperatures fails to meet the sealing compression requirements of automotive components. Therefore, developing a low-compression-period single-component liquid silicone rubber with excellent adhesion to substrates after heat curing for sealing and bonding in various automotive, industrial, and electronic components, especially for sealing and bonding applications of in-situ curing gaskets (CIPG), to replace traditional sealing strips, is of significant research and development importance. Summary of the Invention

[0005] The purpose of this invention is to provide a self-adhesive single-component liquid silicone rubber with low compression set and its preparation method. This silicone rubber exhibits excellent adhesion to various substrates such as stainless steel, aluminum, copper, Kovar alloy, nylon, polycarbonate, and PBT; it also exhibits excellent compression set after high-temperature aging; it can be stored at 25°C for more than 9 months and can be rapidly and completely cured within 5 minutes when heated at 150°C; its tensile strength is ≥6MPa, elongation at break is ≥350%, and Shore A hardness is 40-50. It can be used in the in-situ curing gasket (CIPG) process for waterproof sealing of housings in new energy electric vehicles, household appliances, etc.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] The main objective of this invention is to provide a self-adhesive single-component liquid silicone rubber with low compression set, comprising the following components in parts by weight:

[0008] The composition includes: 100-150 parts of divinyl dimethylsiloxane, 30-50 parts of silica, 6-10 parts of hexamethyldisilazane, 0-0.3 parts of tetramethyldisilazane, 7-15 parts of polydimethylmethylvinylsiloxane, 4-10 parts of polydimethylmethylhydrosiloxane, 0.3-0.5 parts of inhibitor, 0.2-0.5 parts of catalyst, 0.05-0.5 parts of primary functional additive, and 0.3-1 parts of secondary functional additive.

[0009] The first functional adjuvant is one or more compounds having the structure shown in formula (I):

[0010]

[0011] The second functional additive is an addition reaction product of 1,3,5,7-tetramethylcyclotetrasiloxane with glycidyl methacrylate / or glycidyl acrylate, as well as 4-allyl catechol and N-allyl maleimide derivatives under the action of platinum catalyst.

[0012] In this invention, the preparation method of the first functional additive is as follows: triazole compounds and o-diphenol 4-chlorophenylboronic acid react in a mixed solution of tris(dibenzylacetone)dipalladium(O), tri-tert-butylphosphine, 1,4-dioxane, toluene and potassium acetate. After reacting at 100°C under a nitrogen atmosphere for 5-8 hours, water is added for washing. The aqueous phase is then extracted with ethyl acetate and combined with the organic phase. The organic phase is dried over anhydrous magnesium sulfate, filtered, concentrated, and purified by rapid column chromatography to obtain the first functional additive.

[0013] Further, the triazole compound is one of benzotriazole, 5-methyl-1H-benzotriazole, 1,2,4-triazole, and 1H-1,2,3-triazole; the molar ratio of the triazole compound to o-diphenol 4-chlorophenylboronic acid is 1 to 1.05:1.

[0014] In this invention, the preparation method of the second functional additive is as follows: 1,3,5,7-tetramethylcyclotetrasiloxane, toluene and platinum catalyst are added to a three-necked flask and mixed and stirred evenly. The temperature is raised to 80°C and glycidyl methacrylate / or glycidyl acrylate, as well as 4-allyl catechol and N-allyl maleimide derivatives are added dropwise in sequence. After the addition is completed, the temperature is raised to 110°C and stirred for 4-8 hours. After the reaction is completed, the mixture is cooled to room temperature, filtered, and concentrated to obtain the second functional additive.

[0015] Furthermore, the N-allylmaleimide derivative is a Michael addition product of N-allylmaleimide and γ-mercaptopropyltrimethoxysilane / or γ-mercaptopropyltriethoxysilane / or γ-mercaptopropylmethyldimethoxysilane, i.e. One of the following: the molar ratio of 1,3,5,7-tetramethylcyclotetrasiloxane to glycidyl methacrylate / or glycidyl acrylate, and 4-allyl catechol and N-allyl maleimide derivatives is 1:1:1:0.1 to 0.5; the mass of toluene is 50% to 80% of the mass of 1,3,5,7-tetramethylcyclotetrasiloxane; the platinum catalyst is selected from platinum catalysts supported on alumina, titanium dioxide, activated carbon, etc.; the mass content of platinum atoms in the reaction system is 10 to 20 ppm.

[0016] In this invention, the viscosity of the double-ended vinyl polydimethylsiloxane is 500–20000 mPa·s; the viscosity of the polydimethylmethylvinylsiloxane is 1000–3000 mPa·s, and the vinyl content is 3–8 wt%; the viscosity of the polydimethylmethylhydrosiloxane is 20–80 mPa·s, and the hydrogen content is 0.4–0.7 wt%; the silica is 300 m... 2 / g、380m 2 / g、400m 2 / g of fumed silica (silica produced by gas-phase polymerization); the catalyst is a platinum complex of bis(phenylacetylene)(cyclooct-1,5-diene), a platinum complex of bis(1-ethynylcyclohexanol)(cyclooct-1,5-diene), a platinum complex of bis(phenylacetylene)(1,5-dimethylcyclooct-1,5-diene), a platinum complex of bis(1-ethynylcyclohexanol)(1,5-dimethylcyclooct-1,5-diene), or a platinum complex of bis(3-phenyl-1-butyn-3-ol). One of the (cyclooctyl-1,5-diene)platinum complexes, wherein the effective content of platinum atoms is 5000-15000 ppm; the inhibitor is one or more of 1-ethynylcyclohexanol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-dodecyn-3-ol, 3,7,11-trimethyldodecyn-3-ol, di[(1,1,dimethyl-2-propynyl)oxy]dimethylsilane, and diallyl maleate.

[0017] Another objective of this invention is to provide a method for preparing a self-adhesive single-component liquid silicone rubber with low compression set. The method involves kneading 30-50 parts of silica, 100 parts of diethylenedimethylsiloxane, 6-10 parts of hexamethyldisilazane, and 1.5-3 parts of water in a kneader for 5-8 hours, then heating to 150°C, maintaining a vacuum of ≤-0.08 MPa, and continuing kneading for 2-4 hours. After cooling to room temperature, the mixture is ground using a three-roll mill to obtain a base rubber. Then, the base rubber, 0-50 parts of... A self-adhesive single-component liquid silicone rubber with low compression set is prepared by mixing 7-15 parts of dimethyl methyl vinyl siloxane, 4-10 parts of dimethyl methyl hydrosiloxane, 0.05-0.5 parts of a first functional additive, 0.3-1 part of a second functional additive, 0.3-0.5 parts of an inhibitor, and 0.2-0.5 parts of a catalyst in a planetary mixer at room temperature for 30 minutes, followed by vacuum degassing treatment at room temperature for 15 minutes.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. The liquid silicone rubber prepared by this invention exhibits excellent self-adhesive properties to various substrates such as stainless steel, aluminum, copper, Kovar alloy, nylon, polycarbonate, and PBT. The designed and synthesized first and second functional additives have borate ester, alkoxy, imide, thioether, catechol, ester, epoxy, and silanol groups. During heat curing, some of these groups can react with the hydroxyl groups on the surface of the substrate (stainless steel, aluminum, copper, Kovar alloy, nylon, polycarbonate, PBT, etc.) to form chemical bonds or non-covalent bonds with the substrate. The silanol groups can participate in the crosslinking network of the silicone rubber. The additives act as a "bridge" between the silicone rubber and the substrate, thereby achieving a strong bond.

[0020] 2. The liquid silicone rubber prepared by this invention exhibits excellent compression set properties after high-temperature aging, meeting the sealing and compression requirements of automotive parts. In addition to the aforementioned thickening effect, the designed and synthesized first and second functional additives also act as low-pressure deformation control agents. The triazole and thioether groups in their molecular structure can capture free radicals to prevent the oxidative decomposition of side chain groups, improving the high-temperature aging thermal stability of the silicone rubber. This allows the silicone rubber to retain good resilience after high-temperature aging compression, facilitating the disassembly and repair of automotive, industrial, and electronic components without damage.

[0021] 3. The liquid silicone rubber prepared by this invention is a single component and can be used directly. It will not cause material instability due to uneven mixing of the rubber compound, and the dispensing construction is convenient. The storage period at 25°C is ≥9 months. Compared with the single-component addition-curing liquid silicone rubber on the market, the silicone rubber of this invention does not require cold chain transportation and frozen storage, and has a longer storage time. The first and second functional additives will not affect the curing of the silicone rubber. When used, it can be quickly and completely cured within 5 minutes by heating to 150°C.

[0022] 4. The liquid silicone rubber prepared by this invention meets the dispensing process requirements of the In-Situ Curing Gasket (CIPG) process before curing, and meets the waterproof sealing requirements of the In-Situ Curing Gasket (CIPG) process after curing and assembly. Detailed Implementation

[0023] To better explain the present invention, the following detailed description is provided in conjunction with embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0024] Example 1

[0025] Based on mass parts, 50 parts with a specific surface area of ​​380 m² 2 / g of fumed silica, 100 parts of divinyl-terminated polydimethylsiloxane with a viscosity of 10000mPa.s, 9 parts of hexamethyldisilazane, and 2.5 parts of water were kneaded in a kneader for 7 hours. The material was then heated to 150℃, and kneaded for another 3 hours while maintaining a vacuum of ≤-0.08MPa. After cooling, the mixture was ground through a three-roll mill to obtain the base adhesive. Then, 150 parts of the base adhesive, 50 parts of divinyl-terminated polydimethylsiloxane with a viscosity of 500mPa.s, and 7 parts of polydimethylmethylethylene with a viscosity of 2000mPa.s and a vinyl content of 6wt% were combined. The following mixtures were prepared by mixing 8 parts of polydimethylmethylhydrosiloxane with a viscosity of 50 mPa·s and a hydrogen content of 0.7 wt%, 0.3 parts of primary functional additive A, 0.75 parts of secondary functional additive A, 0.3 parts of inhibitor (1-ethynylcyclohexanol), and 0.4 parts of catalyst [bis(phenylacetylene)(cyclooctyl-1,5-diene)platinum complex with an effective platinum atom content of 5000 ppm] in a planetary mixer at room temperature for 30 min, followed by vacuum degassing treatment at room temperature for 15 min to obtain a self-adhesive single-component liquid silicone rubber 1 with low compression set.

[0026] Of the above components,

[0027] The first functional adjuvant A is a compound having the following structural formula:

[0028]

[0029] The first functional additive A was prepared by the following method, with the specific steps as follows: Under a nitrogen atmosphere, 122.69 g (1.03 mol) benzotriazole, 230.45 g (1.0 mol) o-diphenol 4-chlorophenylboronic acid, 2.29 g (2.5 mmol) tris(dibenzylacetone)dipalladium(O), 1.01 g (5 mmol) tri-tert-butylphosphine, 117.77 g (1.2 mol) potassium acetate, 800 mL 1,4-dioxane and 200 mL toluene were mixed evenly and stirred at 100 °C for 8 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water, and then the aqueous phase was extracted with ethyl acetate and combined with the organic phase. The organic phase was dried over anhydrous magnesium sulfate, filtered, concentrated, and purified by rapid column chromatography to obtain the first functional additive A.

[0030] The second functional additive A was prepared by the following method, with the specific steps as follows: 240.51 g (1.0 mol) of 1,3,5,7-tetramethylcyclotetrasiloxane, 2.8 g of platinum catalyst supported on an alumina support (the amount of platinum atoms in the reaction system was 10 ppm), and 150 g of toluene were added to a three-necked flask and mixed thoroughly. The mixture was then heated to 80 °C and added dropwise in the following order: 142.15 g (1.0 mol) of glycidyl methacrylate, 150.17 g (1.0 mol) of 4-allyl catechol, and 100.0 g (0.3 mol) of... After the addition is complete, the temperature is raised to 110℃ and stirred for 6 hours. After the reaction is complete, the mixture is cooled to room temperature, filtered, and concentrated to obtain the second functional additive A.

[0031] Example 2

[0032] Based on mass fractions, 45 parts with a specific surface area of ​​400 m² 2 / g of fumed silica, 100 parts of double-ended vinyl polydimethylsiloxane with a viscosity of 8000 mPa·s, 10 parts of hexamethyldisilazane, and 3 parts of water were kneaded in a kneader for 8 hours. The material was then heated to 150°C, and kneaded for another 4 hours while maintaining a vacuum of ≤-0.08 MPa. After cooling, the mixture was ground through a three-roll mill to obtain the base colloid. Then, 145 parts of the base colloid, 45 parts of double-ended vinyl polydimethylsiloxane with a viscosity of 3000 mPa·s, 10 parts of polydimethylmethylvinylsiloxane with a viscosity of 1000 mPa·s and a vinyl content of 3 wt%, and 4 parts of... A self-adhesive single-component liquid silicone rubber with low compression set was prepared by mixing polydimethylmethylhydrosiloxane with a viscosity of 30 mPa·s and a hydrogen content of 0.45 wt%, 0.5 parts of primary functional additive B, 0.3 parts of secondary functional additive B, 0.5 parts of inhibitor (3-methyl-1-dodecyn-3-ol), and 0.2 parts of catalyst [bis(phenylacetylene)(1,5-dimethylcyclooctyl-1,5-diene)platinum complex with an effective platinum atom content of 10000 ppm] in a planetary mixer at room temperature for 30 min, followed by vacuum degassing treatment at room temperature for 15 min.

[0033] Of the above components,

[0034] The first functional adjuvant B is a compound having the following structural formula:

[0035]

[0036] The first functional additive B was prepared by the following method, with the specific steps as follows: Under a nitrogen atmosphere, 139.81 g (1.05 mol) of 5-methyl-1H-benzotriazole, 230.45 g (1.0 mol) of o-diphenol 4-chlorophenylboronic acid, 2.29 g (2.5 mmol) of tris(dibenzylacetone)dipalladium(O), 1.01 g (5 mmol) of tri-tert-butylphosphine, 117.77 g (1.2 mol) of potassium acetate, 800 mL of 1,4-dioxane, and 200 mL of toluene were mixed evenly and stirred at 100 °C for 8 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water, and then the aqueous phase was extracted with ethyl acetate and combined with the organic phase. The organic phase was dried over anhydrous magnesium sulfate, filtered, concentrated, and purified by rapid column chromatography to obtain the first functional additive B.

[0037] The second functional additive B was prepared by the following method, with the specific steps as follows: 240.51 g (1.0 mol) of 1,3,5,7-tetramethylcyclotetrasiloxane, 4.5 g of platinum catalyst supported on titanium oxide (the amount of platinum atoms in the reaction system was 15 ppm), and 170 g of toluene were added to a three-necked flask and mixed thoroughly. The mixture was then heated to 80 °C and added dropwise in the following order: 128.13 g (1.0 mol) of glycidyl acrylate, 150.17 g (1.0 mol) of 4-allyl catechol, and 166.74 g (0.5 mol). After the addition is complete, the temperature is raised to 110℃ and stirred for 8 hours. After the reaction is complete, the mixture is cooled to room temperature, filtered, and concentrated to obtain the second functional additive B.

[0038] Example 3

[0039] Based on mass fractions, 45 parts with a specific surface area of ​​300 m² 2 / g of fumed silica, 100 parts of divinyl-terminated polydimethylsiloxane with a viscosity of 20000 mPa·s, 7 parts of hexamethyldisilazane, and 2 parts of water were kneaded in a kneader for 6 hours. The material was then heated to 150℃, and kneaded for another 2 hours while maintaining a vacuum of ≤-0.08 MPa. After cooling, the mixture was ground through a three-roll mill to obtain the base adhesive. Then, 145 parts of the base adhesive, 25 parts of divinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, 8 parts of polydimethylmethylvinylsiloxane with a viscosity of 1200 mPa·s and a vinyl content of 5 wt%, and 6 parts of water with a viscosity of 70 mPa·s were added to obtain the base adhesive. The following components were mixed in a planetary mixer at room temperature for 30 min: 0.6 wt% polydimethylmethylhydrosiloxane, 0.3 parts of primary functional additive C, 0.5 parts of secondary functional additive C, 0.4 parts of inhibitor {di[(1,1,dimethyl-2-propynyl)oxy]dimethylsilane}, and 0.5 parts of catalyst [bis(1-ethynylcyclohexanol)(1,5-dimethylcyclooctyl-1,5-diene)platinum complex with an effective platinum atom content of 5000 ppm]. The mixture was then vacuum degassing at room temperature for 15 min to obtain a self-adhesive single-component liquid silicone rubber with low compression set 3.

[0040] Of the above components,

[0041] The first functional adjuvant C is a compound having the following structural formula:

[0042]

[0043] The first functional additive C was prepared by the following method, with the specific steps as follows: Under a nitrogen atmosphere, 70.45 g (1.02 mol) of 1,2,4-triazole, 230.45 g (1.0 mol) of o-diphenol 4-chlorophenylboronic acid, 1.83 g (2.0 mmol) of tris(dibenzylacetone)dipalladium(O), 0.81 g (4 mmol) of tri-tert-butylphosphine, 107.96 g (1.1 mol) of potassium acetate, 700 mL of 1,4-dioxane, and 175 mL of toluene were mixed evenly and stirred at 100 °C for 8 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water, and then the aqueous phase was extracted with ethyl acetate and combined with the organic phase. The organic phase was dried over anhydrous magnesium sulfate, filtered, concentrated, and purified by rapid column chromatography to obtain the first functional additive C.

[0044] The second functional additive C was prepared by the following method, with the specific steps as follows: 240.51 g (1.0 mol) of 1,3,5,7-tetramethylcyclotetrasiloxane, 8 g of platinum catalyst supported on activated carbon (the amount of platinum atoms in the reaction system was 20 ppm), and 190 g of toluene were added to a three-necked flask and mixed thoroughly. The mixture was then heated to 80 °C and added dropwise in the following order: 142.15 g (1.0 mol) of glycidyl methacrylate, 150.17 g (1.0 mol) of 4-allyl catechol, and 150.22 g (0.4 mol) of [the following ingredients were added]. After the addition is complete, the temperature is raised to 110℃ and stirred for 5 hours. After the reaction is complete, the mixture is cooled to room temperature, filtered, and concentrated to obtain the second functional additive C.

[0045] Example 4

[0046] Based on mass fractions, 38 parts with a specific surface area of ​​380 m² 2 / g of fumed silica, 100 parts of divinyl-terminated polydimethylsiloxane with a viscosity of 10000mPa.s, 7 parts of hexamethyldisilazane, and 2 parts of water were kneaded in a kneader for 7 hours. The material was then heated to 150℃, and kneaded for another 2 hours while maintaining a vacuum of ≤-0.08MPa. After cooling, the mixture was ground through a three-roll mill to obtain the base adhesive. Then, 138 parts of the base adhesive, 27 parts of divinyl-terminated polydimethylsiloxane with a viscosity of 1000mPa.s, and 13 parts of polydimethylmethylvinylsiloxane with a viscosity of 3000mPa.s and a vinyl content of 8wt% were combined. 10 parts of polydimethylmethylhydrosiloxane with a viscosity of 80 mPa·s and a hydrogen content of 0.5 wt%, 0.1 parts of primary functional additive D, 1 part of secondary functional additive D, 0.4 parts of inhibitor (dienyl maleate), and 0.2 parts of catalyst [bis(3-phenyl-1-butyn-3-ol)(cyclooctyl-1,5-diene)platinum complex with an effective platinum atom content of 15000 ppm] were stirred and mixed in a planetary mixer at room temperature for 30 min, and then vacuum degassed at room temperature for 15 min to obtain a self-adhesive single-component liquid silicone rubber with low compression set 4.

[0047] Of the above components,

[0048] The first functional adjuvant D is a compound having the following structural formula:

[0049]

[0050] The first functional additive D was prepared by the following method, with the specific steps as follows: Under a nitrogen atmosphere, 70.45 g (1.02 mol) 1H-1,2,3-triazole, 230.45 g (1.0 mol) o-diphenol 4-chlorophenylboronic acid, 2.29 g (2.5 mmol) tris(dibenzylacetone)dipalladium(O), 1.01 g (5 mmol) tritert-butylphosphine, 117.77 g (1.2 mol) potassium acetate, 700 mL 1,4-dioxane, and 175 mL toluene were mixed evenly and stirred at 100 °C for 5 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water, and then the aqueous phase was extracted with ethyl acetate and combined with the organic phase. The organic phase was dried over anhydrous magnesium sulfate, filtered, concentrated, and purified by rapid column chromatography to obtain the first functional additive D.

[0051] The second functional additive D was prepared by the following method, with the specific steps as follows: 240.51 g (1.0 mol) of 1,3,5,7-tetramethylcyclotetrasiloxane, 4.2 g of platinum catalyst supported on an alumina support (the amount of platinum atoms in the reaction system was 15 ppm), and 125 g of toluene were added to a three-necked flask and mixed thoroughly. The mixture was then heated to 80 °C and added dropwise in the following order: 128.13 g (1.0 mol) of glycidyl acrylate, 150.17 g (1.0 mol) of 4-allyl catechol, and 63.5 g (0.2 mol) of [the following ingredients were added]. After the addition is complete, the temperature is raised to 110℃ and stirred for 4 hours. After the reaction is complete, the mixture is cooled to room temperature, filtered, and concentrated to obtain the second functional additive D.

[0052] Comparative Example 1

[0053] This comparative example serves as a comparative example of Example 1. In Example 1, neither the first functional additive A nor the second functional additive A were added, and all other conditions were the same as in Example 1.

[0054] Comparative Example 2

[0055] This comparative example serves as a comparative example of Example 1. In Example 1, the first functional additive A was not added, and a conventional commercial silane coupling agent system [a mixture of γ-glycidoxypropyltrimethoxysilane (KH-560) and 3-(methacryloyloxy)propyltrimethoxysilane (KH-570) in equal weight ratios] was used to replace the second functional additive A. Other conditions were the same as in Example 1.

[0056] The silicone rubbers prepared in Examples 1-4 and Comparative Examples 1 and 2 were molded at 150°C for 30 min and then subjected to relevant performance tests according to the following methods:

[0057] 1. Hardness: The Shore A hardness of silicone rubber was tested according to GB / T 531.1-2008.

[0058] 2. Tensile strength and elongation at break: Tested according to GB / T 528-2009 method, with a tensile rate of 500 mm / min.

[0059] 3. Tear strength: Tested according to GB / T 529-2008 method, with a tensile rate of 500 mm / min.

[0060] 4. Shear strength: The shear strength of the silicone rubber against aluminum sheet / aluminum sheet, stainless steel / stainless steel, nylon / nylon, and polycarbonate / polycarbonate was tested according to GB / T 7124-2008. After sample preparation, the samples were baked in an oven at 150℃ for 30 minutes.

[0061] 5. Compression set: Tested according to GB / T7759.1-2015 method, with a compression rate of 25%, after compression baking at 177℃ for 22 hours.

[0062] The relevant performance results are shown in Table 1.

[0063] Table 1

[0064]

[0065] As can be seen from the data in Table 1, the liquid silicone rubber prepared by adding self-made first and second functional additives in Examples 1-4 of the present invention exhibits excellent mechanical properties after curing at 150°C for 30 minutes, with a tensile strength ≥6MPa and an elongation at break ≥350%; it also exhibits excellent compression set performance after high-temperature compression aging, with a compression set rate <15%; and it has excellent self-adhesive properties to aluminum sheets, stainless steel, nylon, and polycarbonate, with a shear strength >3.80MPa. The liquid silicone rubber prepared in Comparative Example 1 without the addition of functional additives had virtually no adhesive effect on aluminum sheets, stainless steel, nylon, and polycarbonate, and its compression set was also relatively high (41%). The liquid silicone rubber prepared in Comparative Example 2 with the addition of a conventional commercial silane coupling agent system had some adhesiveness to aluminum sheets and stainless steel, but its shear strength was far inferior to that of Examples 1-4, and its adhesive effect on nylon and polycarbonate was poor. Furthermore, the use of a conventional commercial silane coupling agent system increased the compression set of the silicone rubber from 41% to 58%.

[0066] The above results indicate that the single-component liquid silicone rubber prepared by adding self-made first and second functional additives has excellent mechanical properties, excellent self-adhesion properties to various substrates, and low compression set, which can meet the performance requirements of adhesives for in-situ curing gaskets (CIPG) for waterproof sealing of housings of new energy electric vehicles, household appliances, etc.

[0067] The above-described embodiments are merely preferred embodiments of the present invention. The implementation of the present invention is not limited to any of the embodiments described. Therefore, any modifications, alterations, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered as equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A low compression set, self-adhesive, one-component liquid silicone rubber, characterized in that: It is composed of the following components by mass fraction: double end vinyl polydimethylsiloxane 100-150 parts, white carbon black 30-50 parts, hexamethyl disilazane 6-10 parts, tetramethyl divinyl disilazane 0-0.3 parts, polydimethyl methyl vinyl siloxane 7-15 parts, polydimethyl methyl hydrogen siloxane 4-10 parts, inhibitor 0.3-0.5 parts, catalyst 0.2-0.5 parts, first functional aid 0.05-0.5 parts, second functional aid 0.3-1 parts; The first functional aid is one or more compounds with the structure shown in formula (I): The second functional aid is the addition reaction product of 1,3,5,7-tetramethylcyclotetrasiloxane and glycidyl methacrylate / or glycidyl acrylate, and 4-allyl catechol, N-allyl maleimide derivative under the action of platinum gold catalyst.

2. A low compression set, self-adhesive, one-component liquid silicone rubber according to claim 1, characterized in that: The preparation method of the first functional aid is as follows: triazole compound and 4-chlorobenzenesulfonic acid o-biphenol ester react in a mixed solution of tris(dibenzylideneacetone)dipalladium(0), tri-tert-butylphosphine, 1,4-dioxane, toluene and potassium acetate, after reacting at 100℃ for 5-8h under nitrogen atmosphere, water is added for washing, then the aqueous phase is extracted with ethyl acetate and combined into the organic phase, the organic phase is dried with anhydrous magnesium sulfate, filtered, concentrated, and then purified by flash column chromatography to obtain the first functional aid.

3. A low compression set, self-adhesive, one-component liquid silicone rubber according to claim 2, characterized in that: The triazole compound is one of benzotriazole, 5-methyl-1H-benzotriazole, 1,2,4-triazole and 1H-1,2,3-triazole; the molar ratio of the triazole compound to 4-chlorobenzenesulfonic acid o-biphenol ester is 1-1.05:

1.

4. The self-adhesive one-part liquid silicone rubber with low compression set according to claim 1, characterized in that: The preparation method of the second functional aid is as follows: 1,3,5,7-tetramethylcyclotetrasiloxane, toluene and platinum gold catalyst are added to a three-necked flask and mixed and stirred uniformly, then glycidyl methacrylate / or glycidyl acrylate and 4-allyl catechol, N-allyl maleimide derivative are added dropwise in sequence at 80℃, after the addition is completed, the temperature is raised to 110℃ and stirring is carried out for 4-8h, after the reaction is completed, the reaction system is cooled to room temperature, filtered and concentrated to obtain the second functional aid.

5. A low compression set, self-adhesive, one-component liquid silicone rubber according to claim 1 or 4, characterized in that: The N-allylmaleimide derivative is a Michael addition product of N-allylmaleimide and γ-mercaptopropyltrimethoxysilane / or γ-mercaptopropyltriethoxysilane / or γ-mercaptopropylmethyldimethoxysilane, i.e. is one of the following compounds.

6. A low compression set, self-adhesive, one-component liquid silicone rubber according to claim 1 or 4, characterized in that: The molar ratio of 1,3,5,7-tetramethylcyclotetrasiloxane to glycidyl methacrylate / or glycidyl acrylate and 4-allyl catechol, N-allyl maleimide derivative is 1:1:1:0.1-0.

5.

7. A low compression set, self-adhesive, one-part liquid silicone rubber according to claim 1, characterized in that: The viscosity of the double end vinyl polydimethylsiloxane is 500-20000 mPa.s; the viscosity of the polydimethyl methyl vinyl siloxane is 1000-3000 mPa.s, and the vinyl content is 3-8 wt%; the viscosity of the polydimethyl methyl hydrogen siloxane is 20-80 mPa.s, and the hydrogen content is 0.4-0.7 wt%.

8. A low compression set, self-adhesive, one-part liquid silicone rubber according to claim 1, characterized in that: The white carbon black is one or more of a fumed white carbon black at 300 m 2 / g, 380 m 2 / g, 400 m 2 / g.

9. A low compression set, self-adhesive, one-part liquid silicone rubber according to claim 1, characterized in that: The catalyst is one of bis(phenylacetylene)(cycloocta-1,5-diene) platinum complex, bis(1-ethynylcyclohexanol)(cycloocta-1,5-diene) platinum complex, bis(phenylacetylene)(1,5-dimethylcycloocta-1,5-diene) platinum complex, bis(1-ethynylcyclohexanol)(1,5-dimethylcycloocta-1,5-diene) platinum complex, bis(3-phenyl-1-butyne-3-ol)(cycloocta-1,5-diene) platinum complex, wherein the effective content of platinum atom is 5000-15000 ppm.

10. A process for the preparation of a low compression set self-adhesive one-component liquid silicone rubber according to any one of claims 1 to 9, characterized in that: 30-50 parts of white carbon black, 100 parts of bis-vinyl terminated polydimethylsiloxane, 6-10 parts of hexamethyldisilazane and 1.5-3 parts of water are kneaded in a kneader for 5-8 hours, then the temperature is raised to 150 DEG C, the vacuum degree is kept at less than or equal to -0.08 MPa, and the kneading is continued for 2-4 hours; after cooling to room temperature, the base rubber is obtained by three-roll milling; then the base rubber, 0-50 parts of bis-vinyl terminated polydimethylsiloxane, 7-15 parts of polydimethylmethylvinylsiloxane, 4-10 parts of polydimethylmethylhydrosiloxane, 0.05-0.5 parts of the first functional aid, 0.3-1 parts of the second functional aid, 0.3-0.5 parts of the inhibitor and 0.2-0.5 parts of the catalyst are stirred and mixed in a planetary mixer at room temperature for 30 minutes, and then vacuum degassing treatment is carried out at room temperature for 15 minutes to obtain the low compression set self-adhesive single-component liquid silicone rubber.

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