Organosilicone gel capable of being cured at normal temperature as well as preparation method and application of organosilicone gel

Abstract

The invention relates to the technical field of organosilicone materials, in particular to organosilicone gel capable of being cured at the normal temperature and a preparation method and application thereof.The organosilicone gel comprises an initiator, a cross-linking agent, a catalyst, a tackifier and modified organosilicone resin, the initiator is a water-soluble redox system initiator, and the cross-linking agent is a water-soluble polycarboxylate water-soluble polycarboxylate water-soluble polycarboxylate water-soluble polycarboxylate water-soluble polycarboxylate water-soluble polycarboxylate water-soluble polycarboxylate water-soluble polycarboxylate. The modified organic silicon resin comprises an epoxy-organic silicon copolymer and a curing agent, and the molar ratio of the epoxy-organic silicon copolymer to the curing agent is (1-3): (1-1.5); the epoxy-organosilicon copolymer comprises a silane monomer containing a benzyl group and dimethyl diethoxy silane, and the curing agent is aliphatic polyamine. The prepared organosilicone gel is short in curing time and can be cured at normal temperature, and the weather resistance and water resistance of the organosilicone gel are improved.

Description

Technical Field

[0001] The present application relates to the technical field of preparation of organic silicon materials, and specifically to a room-temperature curable organic silicon gel, a preparation method thereof, and an application thereof. Background Art

[0002] Silicone compounds are compounds with repeating Si-O-Si groups as the backbone, with other organic groups attached to the silicon atoms. Simply put, silicone elastomers are silicon-containing network polymers that exist in various forms and have varying degrees of crosslinking. They are primarily categorized by their properties: white, smooth powder-like silicone resin microspheres, silicone resin emulsions, and colorless, gel-like silicone elastomer gels. Silicone elastomers are widely used in industries such as electronics, medical, leather, shipbuilding, and daily chemicals due to their excellent thermal stability, electrical insulation, ozone resistance, and physiological inertness.

[0003] Silicone gel has good thermal stability, high oxidative stability, and good radiation resistance. However, the curing temperature of silicone gel is relatively high and the curing time is long. This makes it difficult to cure silicone at room temperature when used as a coating material.

[0004] Therefore, we still need to further research and develop it to overcome the problems existing in the existing technology. Summary of the Invention

[0005] The present invention aims to address the problems existing in the prior art by providing a room-temperature curable organosilicon gel, its preparation method, and its application. This solution features a simple and easy preparation method, enabling the organosilicon gel to cure at room temperature, further shortening the curing time and further improving its weather resistance and water resistance. It is suitable for use as a coating material on automotive windows, building glass windows, or glass exterior walls.

[0006] In order to achieve the above object of the invention, the specific technical solution of the present invention is:

[0007] In a first aspect, the present invention provides a room-temperature curable silicone gel, comprising an initiator, a crosslinking agent, a catalyst, a tackifier, and a modified silicone resin; the initiator is a water-soluble redox system initiator; the modified silicone resin comprises an epoxy-silicone copolymer and a curing agent, wherein the mass ratio of the epoxy-silicone copolymer to the curing agent is 1-3:1-1.5;

[0008] The epoxy-organic silicon copolymer comprises a benzyl-containing silane monomer, an epoxy resin, and dimethyldiethoxysilane, and the curing agent is an aliphatic polyamine;

[0009] The mass ratio of the initiator, the crosslinking agent and the modified silicone resin is 1:3-7:1-10; the mass ratio of the catalyst and the tackifier is 1-3:2-4; and the ratio of the total mass of the initiator, the crosslinking agent and the modified silicone resin to the total mass of the catalyst and the tackifier is 1-3:2-5.

[0010] Furthermore, in a room temperature curable silicone gel, by introducing a modified silicone resin and a water-soluble redox system initiator, during the curing process of the silicone gel, the Ph-OH group and the silanol (Si-OH) in the silicone resin react to form a new Si-O-Ph bond. The formation of this Si-O-Ph bond not only further consumes the residual Si-OH groups at the end of the resin molecular chain, but also increases the cross-linking degree of the resin, thereby effectively inhibiting the "back-biting" reaction caused by Si-OH at high temperatures. For general silicone resins that do not contain phenolic hydroxyl groups, simply increasing the curing temperature has a very limited effect on improving the thermal properties of the resin. In the presence of oxygen, the additional Si-O-Ph cross-linking network increases the stability of the resin structure, hinders the dissolution and diffusion of oxygen at high temperatures, and inhibits the oxidative degradation of organic groups.

[0011] Among room-temperature curable silicone gels, epoxy resins, in addition to their excellent adhesion, heat resistance, and mechanical properties, also boast a distinct advantage: a wide selection of curing agents. This allows for the preparation of epoxy resin materials with varying properties. Common curing agents for epoxy resins include amines, anhydrides, and phenols. In addition to these low-molecular-weight compounds, many organic resins can also be cured through the use of active functional groups within their molecules (such as amino, hydroxyl, and carboxyl groups), thereby achieving copolymerization. The copolymerization reaction between epoxy and silicone resins is typically achieved through the interaction of the terminal hydroxyl groups in the silicone resin with the secondary hydroxyl and epoxy groups in the epoxy resin.

[0012] In a room-temperature curable silicone gel, the curing agent causes the epoxy resin's curing reaction to occur primarily at the epoxy group. Due to the inductive effect, the oxygen atoms on the epoxy group have a higher negative charge, while the terminal carbon atom has a higher positive charge. Therefore, electrophilic reagents (anhydrides) and nucleophilic reagents (primary and secondary amines) can react with the epoxy group to cause ring-opening polymerization, thereby improving the curing efficiency of the silicone resin.

[0013] Furthermore, in a room temperature curable organic silicone gel, the water-soluble redox system initiator is iron-persulfate-sodium formaldehyde sulfoxylate.

[0014] Due to the redox reaction, the activation energy is greatly reduced, and free radicals can be effectively generated in the aqueous phase at low temperatures (20°C-40°C), initiating polymerization and increasing the polymerization rate.

[0015] Furthermore, in a room temperature curable silicone gel, the crosslinking agent is any one of benzoyl peroxide and NN-methylenebisacrylamide.

[0016] The role of the cross-linking agent is to produce chemical bonds between linear molecules, so that the linear molecules are connected to each other to form a network structure, thereby improving the strength and elasticity of the polymer material. Acyl and amino groups can combine with polymers and complexes, thereby improving the curing efficiency of silicone gel.

[0017] Furthermore, in a room temperature curable silicone gel, the catalyst is any one of dibutyltin dilaurate, a tin complex, and dioctyltin.

[0018] By adding a catalyst to introduce an inorganic functional group, the curing time of the modified silicone resin is shortened and the thermal stability of the modified silicone resin is improved.

[0019] Furthermore, in a room temperature curable silicone gel, the tackifier is any one of polyvinyl pyrrolidone K120, cellulose derivatives, and ethylene acid polymers.

[0020] The thickener is easily soluble in water, alcohol, amine and halogenated hydrocarbons, but insoluble in acetone, ether, etc. It has excellent solubility, biocompatibility, physiological inertness, film-forming properties, film protection ability and the ability to composite with various organic and inorganic compounds. It is relatively stable to acid, salt and heat.

[0021] Furthermore, in a room temperature curable silicone gel, the preparation method of the modified silicone resin comprises the following steps:

[0022] S1: weighing a benzyl-containing silane monomer and dimethyldiethoxysilane in proportion, and then subjecting them to hydrolysis, condensation and catalytic hydrogenation to prepare a linear phenolic hydroxyl-containing silicone resin;

[0023] S2: The linear phenolic hydroxyl-containing silicone resin prepared in S1 is mixed with the epoxy resin in a certain proportion, acetone is added thereto for dilution, the mixture is stirred at room temperature to mix uniformly, and the acetone is removed under vacuum to prepare an epoxy-organic silicone copolymer;

[0024] S3: polymerizing the epoxy-organic silicone copolymer prepared in S2 with aliphatic polyamine to prepare a modified silicone resin.

[0025] Further, the preparation of the benzyl-containing silane monomer is as follows:

[0026] Drying and purification of tetrahydrofuran: First, add solid NaOH to a dry reflux condenser for preliminary dehydration. Then, transfer the supernatant to a reflux condenser with a liquid collection flask, add a small amount of sodium filament and benzophenone as an indicator, and further dehydrate until the solution turns blue or blue-purple.

[0027] Preparation of benzyl-containing silane monomers by Grignard reaction: Under anhydrous nitrogen atmosphere, iodine is used to catalyze the reaction of magnesium metal with 1-bromo-4-benzyloxybenzene to produce a benzyloxy-containing Grignard reagent. This benzyloxy-containing Grignard reagent is then reacted with methyltriethoxysilane under certain conditions to produce a benzyl-containing silane monomer.

[0028] Furthermore, in the preparation method of the modified silicone resin, the molar ratio of the benzyl-containing silane monomer to dimethyldiethoxysilane is 1:1-2.

[0029] Furthermore, in the preparation method of the modified silicone resin, the mass ratio of the linear phenolic hydroxyl-containing silicone resin prepared in S1 to the epoxy resin is 2-1:2-4.

[0030] Furthermore, in the preparation method of the modified silicone resin, the aliphatic polyamine is any one of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, and m-xylylenediamine, or a mixture of two thereof.

[0031] Furthermore, in the preparation method of the modified silicone resin, the molar ratio of the epoxy-silicone copolymer prepared in S2 to the aliphatic polyamine is 1-3:1-1.5.

[0032] In a second aspect, the present invention discloses a method for preparing a room temperature curable silicone gel, comprising the following steps:

[0033] (1) Preparation of component A: Mix the initiator, crosslinking agent and modified silicone resin in proportion and stir to prepare component A;

[0034] (2) Preparation of component B: Mix the catalyst and the tackifier in proportion to prepare component B;

[0035] (3) Preparation of organic silicone gel: Add the component A and the component B in proportion to a power mixer and stir under vacuum. After mixing evenly, the organic silicone gel is obtained.

[0036] Furthermore, the mass ratio of the component A to the component B is 1-3:2-5.

[0037] There are two types of reactions in the curing process of epoxy-silicone blends. The first type of reaction occurs between the epoxy resin and the silicone resin, that is, the secondary hydroxyl and epoxy groups in the epoxy resin react with the silanol and phenolic hydroxyl groups in the silicone resin. The second type of reaction occurs in the silicone resin itself, that is, the phenolic hydroxyl groups in the silicone resin form Si-O-Ph bonds with the silanol groups to establish an additional cross-linking network.

[0038] The active groups in the resin exhibit a certain degree of selectivity during cross-linking reactions. At lower temperatures, the silanol and phenolic hydroxyl groups will each first cross-link with the epoxy groups. Once the epoxy groups are consumed, the remaining phenolic hydroxyl groups will react with the silanol groups to form Si-O-Ph bonds at higher temperatures. Reducing the content of phenolic and silanol groups, as well as increasing the degree of cross-linking in the early stages of curing, are detrimental to the formation of Si-O-Ph bonds.

[0039] Preferably, in step (1), the specific conditions for mixing and stirring are vacuum heating at 80-110° C. and stirring for 1-2 hours.

[0040] The vacuum stirring time in step (3) is 20 to 30 minutes, and the vacuum degree is maintained below -0.08 MPa.

[0041] The prepared organic silicone gel has a short curing time and can be cured at room temperature, thereby improving the weather resistance and waterproofness of the organic silicone gel.

[0042] In a third aspect, the present invention discloses an application of the above-mentioned room-temperature curable organic silicone gel, wherein the organic silicone gel is applied as a coating material to automobile windows, glass windows of buildings, and glass exterior walls.

[0043] Compared with the existing technology, the beneficial effects of the present invention are:

[0044] 1. Because the Ph-OH group in this application reacts with the silanol (Si-OH) in the silicone resin to form a new Si-O-Ph bond. The formation of this Si-O-Ph bond not only further consumes the residual Si-OH group at the end of the resin molecular chain, but also increases the cross-linking degree of the resin, thereby effectively inhibiting the "back-bite" reaction caused by Si-OH at high temperature. The formation of the Si-O-Ph bond not only further consumes the residual Si-OH group at the end of the resin molecular chain, but also increases the cross-linking degree of the resin, thereby effectively inhibiting the "back-bite" reaction caused by Si-OH at high temperature. For general silicone resins that do not contain phenolic hydroxyl groups, simply increasing the curing temperature has a very limited effect on improving the thermal properties of the resin. The introduction of phenolic hydroxyl groups can effectively weaken the "unbuttoning" degradation caused by the "back-bite" reaction, thereby greatly improving the thermal stability of the resin. In the presence of oxygen, the additional Si-O-Ph cross-linking network increases the stability of the resin structure, hinders the dissolution and diffusion of oxygen at high temperature, inhibits the oxidative degradation of organic groups, and further improves the thermal stability of the modified silicone resin.

[0045] 2. In the present application, two types of reactions occur during the curing process of the epoxy-silicone blend. The first type of reaction occurs between the epoxy resin and the silicone resin, i.e., the secondary hydroxyl groups and epoxy groups in the epoxy resin react with the silanol groups and phenolic hydroxyl groups in the silicone resin. The second type of reaction occurs within the silicone resin itself, i.e., the phenolic hydroxyl groups in the silicone resin form Si-O-Ph bonds with the silanol groups to establish an additional cross-linking network. The active groups in the resin have a certain degree of selectivity when undergoing cross-linking reactions. i.e., at lower temperatures, the silanol groups and phenolic hydroxyl groups will each first cross-link with the epoxy groups. When the epoxy groups are consumed, the remaining phenolic hydroxyl groups will react with the silanol groups to form Si-O-Ph bonds at higher temperatures. The reduction in the content of phenolic hydroxyl groups and silanol groups and the increase in the cross-linking degree of the resin in the early stage of curing are not conducive to the formation of Si-O-Ph bonds.

[0046] 3. The Si-O-Ph cross-linked network in this application increases the stability of the resin structure, hinders the dissolution and diffusion of oxygen at high temperatures, and inhibits the oxidative degradation of organic groups. The epoxy-organic silicone blend reacts simultaneously with the cyclic curing agent and initiator, allowing the secondary hydroxyl and epoxy groups in the epoxy resin to react with the silanol and phenolic hydroxyl groups in the silicone resin, thereby increasing the curing rate of the organogel. The addition of a catalyst to introduce inorganic functional groups shortens the curing time of the modified silicone resin.

[0047] 4. The organic silicone gel prepared in this application has a short curing time and can be cured at room temperature, thereby improving the weather resistance and waterproofness of the organic silicone gel.

[0048] It should be understood that the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the scope of protection of the present disclosure. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with examples. It should be understood that the specific examples described herein are merely used to explain the present invention and are not intended to limit the present invention. In addition, it should be understood that after reading the content of the present invention, those skilled in the art can make various changes and modifications to the present invention, but these equivalent forms also fall within the scope defined by the appended claims of the application.

[0050] It should be noted that if no specific conditions are specified in the following examples, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0051] In the following embodiments:

[0052] The initiator was iron-persulfate-sodium formaldehyde sulfoxylate, provided by Shanghai Yingxin Laboratory Equipment Co., Ltd.

[0053] The cross-linking agent was NN-methylenebisacrylamide;

[0054] The catalyst is dibutyltin dilaurate;

[0055] The viscosity enhancer is polyvinyl pyrrolidone K120.

[0056] Example 1: Preparation of raw materials and / or intermediates

[0057] A method for preparing a modified silicone resin comprises the following steps:

[0058] S1: 65 g of a benzyl-containing silane monomer and 65 g of dimethyldiethoxysilane were added to 700 mL of tetrahydrofuran, the pH was adjusted to 4 with a 1 mol / L dilute hydrochloric acid solution, the temperature was raised to 70°C and stirred for 7 h for hydrolysis and condensation reaction, and the reaction was concentrated under reduced pressure after completion of the reaction. The concentrated product was added to a mixed solvent of 400 mL of toluene and 300 mL of tetrahydrofuran, followed by addition of 1 g of TFA. 6.5 g of palladium-carbon catalyst was added under a H2 atmosphere, and the temperature was raised to 50°C for catalytic hydrogenation to obtain a linear phenolic hydroxyl-containing silicone resin;

[0059] S2: 40 g of the silicone resin prepared in S1 was mixed with 40 g of the epoxy resin, diluted with acetone, stirred at room temperature, mixed evenly, and the acetone was removed under vacuum to obtain an epoxy-organic silicone copolymer;

[0060] S3: 43 g of the epoxy-silicone copolymer prepared in S2 and 58 g of an aliphatic polyamine were mixed, 600 mL of toluene was added, the temperature was raised to 80° C., and the mixture was stirred at the constant temperature for 1 hour to obtain a modified silicone resin, wherein the aliphatic polyamine was diethylenetriamine.

[0061] The preparation method of the benzyl-containing silane monomer comprises the following steps:

[0062] Drying treatment of tetrahydrofuran (THF): Pour the newly opened analytically pure THF into a 500mL three-necked flask, add an appropriate amount of solid NaOH, install a condenser and a drying tube, and stir and reflux at 85°C for 24h. Subsequently, cool to room temperature and let stand to allow the sodium hydroxide solid to settle. Transfer the supernatant to another 500mL three-necked flask, install a reflux condenser with a liquid collection bottle, and then cut a small amount of metallic sodium into filaments and add it to the flask. Add a small spoonful of benzophenone and maintain reflux at 85°C. When the THF in the flask turns blue or blue-purple, it means that the remaining trace water has been removed, and the THF at this time can be used for Grignard reaction.

[0063] Grignard Reaction: Magnesium turnings (4.43 g, 0.18 mol), methyltriethoxysilane (32.52 g, 0.18 mol), and 80 mL of anhydrous THF were added to a three-necked flask and mixed thoroughly. A small amount of iodine crystals was then added and the mixture was heated to 70°C under a nitrogen atmosphere. 1-Bromo-4-benzyloxybenzene (40.00 g, 0.15 mol) was dissolved in 120 mL of anhydrous THF and transferred to a dropping funnel. Approximately 5 mL of the solution was then discharged into the flask. After the reaction initiated (the solution color gradually changed from yellow-brown to colorless), the temperature was raised to 75°C. The remaining solution in the dropping funnel was added dropwise to the reaction system over 2 hours. After the addition was complete, the mixture was stirred continuously at reflux for 24 hours. The reaction apparatus was converted to an atmospheric distillation apparatus to remove the THF from the mixture. 400 mL of n-hexane was then added. After stirring for 5 minutes, the mixture was allowed to settle. The supernatant was collected and the solvent removed using a rotary evaporator. The crude product is purified by pressure distillation to obtain a colorless, clear, oily liquid, i.e., a benzyl-containing silane monomer.

[0064] Example 2

[0065] A method for preparing a modified silicone resin comprises the following steps:

[0066] S1: 75 g of a benzyl-containing silane monomer and 60 g of dimethyldiethoxysilane were added to 700 mL of tetrahydrofuran, the pH was adjusted to 4 with a 1 mol / L dilute hydrochloric acid solution, the temperature was raised to 70°C and stirred for 7 h for hydrolysis and condensation reaction, and the reaction was concentrated under reduced pressure after completion of the reaction. The concentrated product was added to a mixed solvent of 400 mL of toluene and 300 mL of tetrahydrofuran, followed by addition of 1 g of TFA, and 6.5 g of palladium-carbon catalyst was added under a H2 atmosphere. The temperature was raised to 50°C for catalytic hydrogenation to obtain a linear phenolic hydroxyl-containing silicone resin;

[0067] S2: 55 g of the silicone resin prepared in S1 was mixed with 42 g of the epoxy resin, diluted with acetone, stirred at room temperature, mixed evenly, and the acetone was removed under vacuum to obtain an epoxy-organic silicone copolymer;

[0068] S3: 49 g of the epoxy-silicone copolymer prepared in S2 and 23 g of an aliphatic polyamine were mixed, 600 mL of toluene was added, the temperature was raised to 80° C., and the mixture was stirred at a constant temperature for 1 hour to obtain a modified silicone resin, wherein the aliphatic polyamine was diethylenetriamine.

[0069] The preparation method of the benzyl-containing silane monomer comprises the following steps:

[0070] Drying treatment of tetrahydrofuran (THF): Pour the newly opened analytically pure THF into a 500mL three-necked flask, add an appropriate amount of solid NaOH, install a condenser and a drying tube, and stir and reflux at 85°C for 24h. Subsequently, cool to room temperature and let stand to allow the sodium hydroxide solid to settle. Transfer the supernatant to another 500mL three-necked flask, install a reflux condenser with a liquid collection bottle, and then cut a small amount of metallic sodium into filaments and add it to the flask. Add a small spoonful of benzophenone and maintain reflux at 85°C. When the THF in the flask turns blue or blue-purple, it means that the remaining trace water has been removed, and the THF at this time can be used for Grignard reaction.

[0071] The preparation was carried out by referring to the Grignard reaction in Example 1 to obtain a benzyl-containing silane monomer.

[0072] Example 3

[0073] A method for preparing a modified silicone resin comprises the following steps:

[0074] S1: 88 g of a benzyl-containing silane monomer and 60 g of dimethyldiethoxysilane were added to 700 mL of tetrahydrofuran, the pH was adjusted to 4 with a 1 mol / L dilute hydrochloric acid solution, the temperature was raised to 70°C and stirred for 7 h for hydrolysis and condensation reaction, and the reaction was concentrated under reduced pressure after completion of the reaction. The concentrated product was added to a mixed solvent of 400 mL of toluene and 300 mL of tetrahydrofuran, followed by addition of 1 g of TFA, and 6.5 g of palladium-carbon catalyst was added under a H2 atmosphere. The temperature was raised to 50°C for catalytic hydrogenation to obtain a linear phenolic hydroxyl-containing silicone resin;

[0075] S2: 44 g of the silicone resin prepared in S1 was mixed with 36 g of the epoxy resin, diluted with acetone, stirred at room temperature, mixed evenly, and the acetone was removed under vacuum to obtain an epoxy-organic silicone copolymer;

[0076] S3: 68 g of the epoxy-silicone copolymer prepared in S2 and 32 g of an aliphatic polyamine were mixed, 600 mL of toluene was added, the temperature was raised to 80° C., and the mixture was stirred at a constant temperature for 1 hour to obtain a modified silicone resin, wherein the aliphatic polyamine was diethylenetriamine.

[0077] The preparation method of the benzyl-containing silane monomer comprises the following steps:

[0078] Drying treatment of tetrahydrofuran (THF): Pour the newly opened analytically pure THF into a 500mL three-necked flask, add an appropriate amount of solid NaOH, install a condenser and a drying tube, and stir and reflux at 85°C for 24h. Subsequently, cool to room temperature and let stand to allow the sodium hydroxide solid to settle. Transfer the supernatant to another 500mL three-necked flask, install a reflux condenser with a liquid collection bottle, and then cut a small amount of metallic sodium into filaments and add it to the flask. Add a small spoonful of benzophenone and maintain reflux at 85°C. When the THF in the flask turns blue or blue-purple, it means that the remaining trace water has been removed, and the THF at this time can be used for Grignard reaction.

[0079] The preparation was carried out by referring to the Grignard reaction in Example 1 to obtain a benzyl-containing silane monomer.

[0080] Example 4

[0081] A method for preparing a modified silicone resin comprises the following steps:

[0082] S1: 80 g of a benzyl-containing silane monomer and 55 g of dimethyldiethoxysilane were added to 700 mL of tetrahydrofuran, the pH was adjusted to 4 with a 1 mol / L dilute hydrochloric acid solution, the temperature was raised to 70°C and stirred for 7 h for hydrolysis and condensation reaction, and the reaction was concentrated under reduced pressure after completion of the reaction. The concentrated product was added to a mixed solvent of 400 mL of toluene and 300 mL of tetrahydrofuran, followed by addition of 1 g of TFA, and 6.5 g of palladium-carbon catalyst was added under a H2 atmosphere. The temperature was raised to 50°C for catalytic hydrogenation to obtain a linear phenolic hydroxyl-containing silicone resin;

[0083] S2: 58 g of the silicone resin prepared in S1 was mixed with 46 g of the epoxy resin, diluted with acetone, stirred at room temperature, mixed evenly, and the acetone was removed under vacuum to obtain an epoxy-organic silicone copolymer;

[0084] S3: 55 g of the epoxy-silicone copolymer prepared in S2 and 48 g of an aliphatic polyamine were mixed, 600 mL of toluene was added, the temperature was raised to 80° C., and the mixture was stirred at the constant temperature for 1 hour to obtain a modified silicone resin, wherein the aliphatic polyamine was diethylenetriamine.

[0085] The preparation method of the benzyl-containing silane monomer comprises the following steps:

[0086] Drying treatment of tetrahydrofuran (THF): Pour the newly opened analytically pure THF into a 500mL three-necked flask, add an appropriate amount of solid NaOH, install a condenser and a drying tube, and stir and reflux at 85°C for 24h. Subsequently, cool to room temperature and let stand to allow the sodium hydroxide solid to settle. Transfer the supernatant to another 500mL three-necked flask, install a reflux condenser with a liquid collection bottle, and then cut a small amount of metallic sodium into filaments and add it to the flask. Add a small spoonful of benzophenone and maintain reflux at 85°C. When the THF in the flask turns blue or blue-purple, it means that the remaining trace water has been removed, and the THF at this time can be used for Grignard reaction.

[0087] The preparation was carried out by referring to the Grignard reaction in Example 1 to obtain a benzyl-containing silane monomer.

[0088] Example 5

[0089] A method for preparing a room temperature curable silicone gel comprises the following steps:

[0090] (1) Preparation of Component A: 11 g of initiator, 35 g of crosslinker, and 67 g of modified silicone resin were mixed, heated to 90° C., and stirred for 1.5 h to prepare Component A; wherein the modified silicone resin was prepared in Example 1; (2) Preparation of Component B: 32 g of catalyst and 66 g of tackifier were mixed to prepare Component B;

[0091] (3) Preparation of silicone gel: 10 g of component A and 15 g of component B were added to a power mixer and stirred under vacuum for 25 min, with the vacuum degree maintained below -0.08 MPa. After mixing evenly, the silicone gel was obtained.

[0092] Example 6

[0093] A method for preparing a room temperature curable silicone gel comprises the following steps:

[0094] (1) Preparation of component A: 15 g of initiator, 58 g of crosslinker, and 128 g of modified silicone resin were mixed, heated to 80° C., and stirred for 2 h to prepare component A. The modified silicone resin was prepared in Example 2.

[0095] (2) Preparation of component B: 25 g of catalyst and 78 g of tackifier were mixed to prepare component B;

[0096] (3) Preparation of silicone gel: 12 g of component A and 25 g of component B were added to a power mixer and stirred under vacuum for 30 min, with the vacuum degree maintained below -0.08 MPa. After mixing evenly, the silicone gel was obtained.

[0097] Example 7

[0098] A method for preparing a room temperature curable silicone gel comprises the following steps:

[0099] (1) Preparation of component A: 10 g of initiator, 35 g of crosslinker and 88 g of modified silicone resin were mixed and heated to 110° C. and stirred for 1 h to prepare component A. The modified silicone resin was prepared in Example 3.

[0100] (2) Preparation of component B: 26 g of catalyst and 109 g of tackifier were mixed to prepare component B;

[0101] (3) Preparation of silicone gel: 8 g of component A and 20 g of component B were added to a power mixer and stirred under vacuum for 20 min, with the vacuum degree maintained below -0.08 MPa. After mixing evenly, the silicone gel was obtained.

[0102] Example 8

[0103] A method for preparing a room temperature curable silicone gel comprises the following steps:

[0104] (1) Preparation of component A: 16 g of initiator, 86 g of crosslinker, and 102 g of modified silicone resin were mixed, heated to 90° C., and stirred for 1.5 h to prepare component A. The modified silicone resin was prepared in Example 4.

[0105] (2) Preparation of component B: 20 g of catalyst and 66 g of tackifier were mixed to prepare component B;

[0106] (3) Preparation of silicone gel: 15 g of component A and 35 g of component B were added to a power mixer and stirred under vacuum for 25 min, with the vacuum degree maintained below -0.08 MPa. After mixing evenly, the silicone gel was obtained.

[0107] Example 9

[0108] A method for preparing a room temperature curable silicone gel comprises the following steps:

[0109] (1) Preparation of component A: 8 g of initiator, 50 g of cross-linking agent and 43 g of modified silicone resin were mixed and heated to 90° C. and stirred for 1.5 h to prepare component A. The modified silicone resin was prepared in Example 2.

[0110] (2) Preparation of component B: 31 g of catalyst and 16 g of tackifier were mixed to prepare component B;

[0111] (3) Preparation of silicone gel: 10 g of component A and 27 g of component B were added to a power mixer and stirred under vacuum for 25 min, with the vacuum degree maintained below -0.08 MPa. After mixing evenly, the silicone gel was obtained.

[0112] Example 10

[0113] A method for preparing a room temperature curable silicone gel comprises the following steps:

[0114] (1) Preparation of component A: 13 g of initiator, 38 g of crosslinking agent and 67 g of modified silicone resin were mixed and heated to 90° C. and stirred for 1.5 h to prepare component A. The modified silicone resin was prepared in Example 2.

[0115] (2) Preparation of component B: 28 g of catalyst and 15 g of tackifier were mixed to prepare component B;

[0116] (3) Preparation of silicone gel: 18 g of component A and 45 g of component B were added to a power mixer and stirred under vacuum for 25 min, with the vacuum degree maintained below -0.08 MPa. After mixing evenly, the silicone gel was obtained.

[0117] Comparative Example 1

[0118] The room temperature curable silicone gel was prepared according to the method of Example 6, except that no modified silicone resin was added.

[0119] Comparative Example 2

[0120] A room temperature curable silicone gel was prepared according to the method of Example 6, except that the modified silicone resin was replaced by epoxy resin.

[0121] Comparative Example 3

[0122] The room temperature curable organosilicon gel was prepared according to the method of Example 6, except that the catalyst dibutyltin dilaurate was not added.

[0123] Comparative Example 4

[0124] The room temperature curable silicone gel was prepared according to the method of Example 6, except that the crosslinking agent was NN-methylenebisacrylamide.

[0125] Performance testing

[0126] Test 1: Curing time

[0127] The surface drying time of silicone gel was tested according to GB / T 13477.5-2002 (B method). The irradiation curing was carried out using UV light (365nm) with an irradiation energy of 2400mW / cm 2 , the curing time was detected at 25℃ and 45℃.

[0128] Test 2: Mechanical strength after full curing

[0129] The mechanical strength of silicone gel after complete curing was tested in accordance with GB / T 34709-2017.

[0130] Test samples: The room-temperature curable silicone gels of Examples 1-6 were used as example samples; the room-temperature curable silicone gels of Comparative Examples 1-4 were used as comparative example samples.

[0131] Test results: Test results of curing time and mechanical strength of room temperature curable silicone gels of Examples 1-6 and Comparative Examples 1-4 at different temperatures.

[0132] Table 1

[0133]

[0134] As shown in Table 1, among Examples 4-9, Example 5 has the shortest curing time at different temperatures and the best mechanical strength, indicating that the ratio of the initiator, crosslinking agent and modified silicone resin has a greater impact on the curing efficiency of the silicone gel.

[0135] As shown in Table 1, the curing time of the silicone gel prepared in Comparative Example 1 is the longest and the curing efficiency is low, which shows that the modified silicone resin has a great influence on the curing time of the silicone gel. The addition of the modified silicone resin significantly improves the curing performance of the silicone gel.

[0136] This background section is provided to generally present the context of the invention, and the work of the presently named inventors, the work to the extent described in this background section, and aspects of the description in this section that did not constitute prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art to the present invention.

[0137] The above-described embodiments merely represent specific implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection of the present application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the technical concept of the present application, and all such variations and improvements fall within the scope of protection of the present application.

Claims

1. A room temperature curable silicone gel, characterized in that: The organic silicone gel comprises an initiator, a cross-linking agent, a catalyst, a tackifier and a modified organic silicone resin; the initiator is a water-soluble redox system initiator; the modified organic silicone resin comprises an epoxy-organic silicone copolymer and a curing agent, and the mass ratio of the epoxy-organic silicone copolymer to the curing agent is 1-3:1-1.5; The epoxy-organic silicon copolymer comprises a benzyl-containing silane monomer, an epoxy resin, and dimethyldiethoxysilane, and the curing agent is an aliphatic polyamine; The mass ratio of the initiator, the crosslinking agent and the modified silicone resin is 1:3-7:1-10; the mass ratio of the catalyst and the tackifier is 1-3:2-4; and the ratio of the total mass of the initiator, the crosslinking agent and the modified silicone resin to the total mass of the catalyst and the tackifier is 1-3:2-5.

2. The room temperature curable silicone gel according to claim 1, characterized in that: The water-soluble redox system initiator is iron-persulfate-sodium formaldehyde sulfoxylate; the cross-linking agent is any one of benzoyl peroxide and NN-methylenebisacrylamide.

3. The room temperature curable silicone gel according to claim 1, characterized in that: The catalyst is any one of dibutyltin dilaurate, a tin complex, and dioctyltin.

4. The room temperature curable silicone gel according to claim 1, characterized in that The thickener is any one of polyvinyl pyrrolidone K120, cellulose derivatives, and ethylene acid polymers.

5. The room temperature curable silicone gel according to claim 1, characterized in that: The preparation method of the modified silicone resin comprises the following steps: S1: weighing a benzyl-containing silane monomer and dimethyldiethoxysilane in proportion, and then subjecting them to hydrolysis, condensation and catalytic hydrogenation to prepare a linear phenolic hydroxyl-containing silicone resin; S2: The linear phenolic hydroxyl-containing silicone resin prepared in S1 is mixed with the epoxy resin in a certain proportion, acetone is added thereto for dilution, the mixture is stirred at room temperature to mix uniformly, and the acetone is removed under vacuum to prepare an epoxy-organic silicone copolymer; S3: polymerizing the epoxy-organic silicone copolymer prepared in S2 with aliphatic polyamine to prepare a modified silicone resin.

6. The room temperature curable silicone gel according to claim 5, characterized in that: The preparation steps of the benzyl-containing silane monomer are as follows: Drying and purification of tetrahydrofuran: First, add solid NaOH to a drying reflux condenser for preliminary dehydration to obtain a supernatant; then transfer the supernatant to a reflux condenser with a liquid collection bottle, add a small amount of sodium filament and benzophenone indicator to further dehydrate, until the solution turns blue or blue-purple; Preparation of benzyl-containing silane monomers by Grignard reaction: In anhydrous and nitrogen atmosphere, iodine is used to catalyze the reaction of magnesium metal and 1-bromo-4-benzyloxybenzene to generate a benzyloxy-containing Grignard reagent. This benzyloxy-containing Grignard reagent is then reacted with methyltriethoxysilane under certain conditions to obtain a benzyl-containing silane monomer.

7. The room temperature curable silicone gel according to claim 5, characterized in that: In the preparation method of the modified silicone resin, the molar ratio of the benzyl-containing silane monomer to dimethyldiethoxysilane is 1:1-2; the mass ratio of the linear phenolic hydroxyl-containing silicone resin prepared in S1 to the epoxy resin is 2-1:2-4; the aliphatic polyamine is any one or a mixture of two of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, and meta-xylylenediamine; and the molar ratio of the epoxy-silicone copolymer prepared in S2 to the aliphatic polyamine is 1-3:1-1.

5.

8. The method for preparing a room temperature curable silicone gel according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Preparation of component A: Mix the initiator, crosslinking agent and modified silicone resin in proportion and stir to prepare component A; (2) Preparation of component B: Mix the catalyst and the tackifier in proportion to prepare component B; (3) Preparation of organic silicone gel: Add the component A and the component B in proportion to a power mixer and stir under vacuum. After mixing evenly, the organic silicone gel is obtained.

9. The method for preparing a room temperature curable silicone gel according to claim 8, characterized in that: In the step (1), the specific conditions for mixing and stirring are vacuum heating at 80-110° C. and stirring for 1-2 hours; The vacuum stirring time in step (3) is 20 to 30 minutes, and the vacuum degree is maintained below -0.08 MPa.

10. The use of a room temperature curable silicone gel according to any one of claims 1 to 7, characterized in that: The organosilicon gel is used as a coating material for automobile windows, glass windows or glass exterior walls of buildings.

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