Preparation method of silicone rubber and silicone rubber

Abstract

The invention discloses a preparation method of silicone rubber and the silicone rubber, and belongs to the field of silicone rubber. The preparation method comprises the following steps: dispersing fumed silica in an acid solution to obtain a fumed silica solution, dispersing chitosan in a dilute acid solution to obtain a chitosan solution, mixing the fumed silica solution and the chitosan solution, stirring, centrifuging, washing and drying to obtain a coated product; mixing the coated product, magnesium hydroxide, raw rubber, a cross-linking agent, a vulcanizing agent and a catalyst, heating and kneading, and vacuumizing to obtain initial silicone rubber; the preparation method comprises the following steps: dissolving 1-hydroxycyclohexyl phenyl ketone into an organic solvent to obtain a solution A, mixing acrylic acid, phenyl bis (2, 4, 6-trimethylbenzoyl) phosphine oxide and titanium dioxide to obtain a solution B, soaking initial silicone rubber into the solution A, taking out, airing, soaking into the solution B, and carrying out ultraviolet curing, cleaning and airing to obtain the silicone rubber. The heat-conducting property, the mechanical property and the wet friction property of the silicone rubber are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicone rubber, and particularly relates to a preparation method of silicone rubber and the silicone rubber. Background Art

[0002] The application of silicone rubber in the synthetic leather field has been increasingly widespread. Under dry conditions, the surface of silicone rubber is astringent, and the frictional force with the surfaces of leather, floors, etc. is relatively large. However, in a humid environment with water, the frictional force will decrease significantly. Especially in rainy days or humid environments, the frictional force between the surface of silicone rubber and the surfaces of balls, floors, etc. decreases, resulting in a slipping phenomenon, thus affecting its normal use. Therefore, there is a need to provide a silicone rubber that can provide a high frictional force in a humid environment. Summary of the Invention

[0003] The main object of the present invention is to provide a preparation method of silicone rubber and the silicone rubber, so as to solve the technical problem that the hydrophilic property of silicone rubber is insufficient and it is difficult to provide a high frictional force in a humid environment.

[0004] To achieve the above object, the present invention provides a preparation method of silicone rubber, including the following steps: S10: Disperse fumed silica in an acid solution to obtain a fumed silica solution, disperse chitosan in a dilute acid solution to obtain a chitosan solution, then mix the fumed silica solution and the chitosan solution, and obtain a coated product through stirring, centrifugation, washing, and drying; S20: Mix the coated product, magnesium hydroxide, raw rubber, crosslinking agent, vulcanizing agent, and catalyst, heat and knead, and obtain an initial silicone rubber after evacuating; S30: Dissolve 1-hydroxycyclohexyl phenyl ketone in an organic solvent to obtain solution A, mix acrylic acid, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and titanium dioxide to obtain solution B, soak the initial silicone rubber in solution A, take it out and air-dry, then soak it in solution B, and perform ultraviolet curing, cleaning, and air-drying to obtain the silicone rubber.

[0005] In some embodiments of the present invention, the average particle size range of the fumed silica is 10 nm to 50 nm.

[0006] In some embodiments of the present invention, in the step of heat kneading, the heating temperature is 100 °C to 150 °C.

[0007] In some embodiments of the present invention, the magnesium hydroxide includes small particle size magnesium hydroxide and large particle size magnesium hydroxide, the average particle size of the small particle size magnesium hydroxide is 0.1 μm to 2 μm, and the average particle size of the large particle size magnesium hydroxide is 5 μm to 20 μm.

[0008] In some embodiments of the present invention, the raw rubber includes at least one of methyl vinyl silicone rubber raw rubber and α,ω-dihydroxypolydimethylsiloxane.

[0009] In some embodiments of the present invention, the raw rubber is α,ω-dihydroxypolydimethylsiloxane, and the viscosity of the α,ω-dihydroxypolydimethylsiloxane is 50000 cps to 60000 cps.

[0010] In some embodiments of the present invention, the crosslinking agent includes trimethoxysilane; and / or, the catalyst includes dibutyltin dilaurate; and / or, the vulcanizing agent includes at least one of bis(2,5-dimethyl-2,5-di(t-butylperoxy)hexane), bis(2,4-dichlorobenzoyl) peroxide, and platinum vulcanizing agent.

[0011] In some embodiments of the present invention, the mass ratio of the coated product, magnesium hydroxide, raw rubber, crosslinking agent, vulcanizing agent, and catalyst is (5 - 20):(10 - 30):(40 - 60):(2 - 5):(1 - 3):(0.1 - 1).

[0012] In some embodiments of the present invention, the mass ratio of acrylic acid, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and titanium dioxide is (50 - 70):(5 - 20):(5 - 20).

[0013] The present invention also provides a silicone rubber prepared by the preparation method as described above.

[0014] The beneficial effects that the present invention can achieve: The silicone rubber of the present invention uses fumed silica as a reinforcing filler, and the fumed silica is coated with chitosan, which can not only enhance the strength of the silicone rubber and improve the mechanical properties of the silicone rubber. In addition, a hydrophilic surface is formed by treating with acrylic acid and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and titanium dioxide is doped on the hydrophilic surface. Titanium dioxide can be firmly fixed to the silicone rubber by means of the hydrophilic surface energy, further improving the hydrophilic property of the silicone rubber. At the same time, the doping of titanium dioxide can also improve the stability of the hydrophilic surface of the silicone rubber, reduce the risk of shedding of the hydrophilic surface, especially in dynamic environments such as friction, extend the hydrophilic effect of the silicone rubber, enable it to quickly absorb the water film at the interface in a humid environment, reduce the water lubrication effect, increase the direct contact area between the silicone rubber and the ground, improve the friction force, and enhance the anti-slip effect. It can also help improve the heat resistance and aging resistance of the silicone rubber. In addition, the addition of magnesium hydroxide greatly improves the thermal conductivity and flame retardancy of the silicone rubber. The silicone rubber of the present invention has good mechanical properties, thermal conductivity, flame retardancy, heat resistance and aging resistance, and good hydrophilicity, and can be applied to fields such as medical treatment, electronics, clothing and shoes, and cables. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces the attached drawings required for the description of the embodiments or the prior art. Obviously, the attached drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other attached drawings can be obtained based on the structures shown in these attached drawings.

[0016] Figure 1 It is a schematic flow chart of the preparation of a silicone rubber of the present invention.

[0017] The realization of the object, functional features and advantages of the present invention will be further described with reference to the embodiments and the attached drawings. Specific embodiments

[0018] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the attached drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0020] In the present invention, descriptions such as "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0021] The present invention provides a silicone rubber and a preparation method thereof. Referring to Figure 1 , the preparation method includes the following steps: S10. Disperse fumed silica in an acid solution to obtain a fumed silica solution, disperse chitosan in a dilute acid solution to obtain a chitosan solution, then mix the fumed silica solution and the chitosan solution, and obtain a coated product through stirring, centrifugation, washing and drying; S20. Mix the coated product, magnesium hydroxide, raw rubber, crosslinking agent, vulcanizing agent and catalyst, heat and knead, and obtain the initial silicone rubber after vacuum pumping; S30. Dissolve 1-hydroxycyclohexyl phenyl ketone in an organic solvent to obtain solution A. Mix acrylic acid, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and titanium dioxide to obtain solution B. Immerse the initial silicone rubber in solution A, take it out and let it dry, then immerse it in solution B, and perform ultraviolet curing, followed by cleaning and drying to obtain the silicone rubber.

[0022] The silicone rubber of the present invention uses fumed silica as a reinforcing filler, and the fumed silica is coated with chitosan. This can not only enhance the strength of the silicone rubber and improve its mechanical properties. In addition, a hydrophilic surface is formed by treating with acrylic acid and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and titanium dioxide is doped on the hydrophilic surface. Titanium dioxide can be firmly fixed to the silicone rubber by virtue of the hydrophilic surface energy, further improving the hydrophilic property of the silicone rubber. At the same time, the doping of titanium dioxide can also improve the stability of the hydrophilic surface of the silicone rubber, reduce the risk of shedding of the hydrophilic surface, especially in dynamic environments such as friction, extend the hydrophilic effect of the silicone rubber, enable it to quickly absorb the water film at the interface in a humid environment, reduce the water lubrication effect, increase the direct contact area between the silicone rubber and the ground, improve the friction force, and enhance the anti-slip effect. It can also help improve the heat resistance and aging resistance of the silicone rubber. In addition, the addition of magnesium hydroxide greatly improves the thermal conductivity and flame retardancy of the silicone rubber. The silicone rubber of the present invention has good mechanical properties, thermal conductivity, flame retardancy, heat resistance and aging resistance, and good hydrophilicity, and can be applied to fields such as medical, electronics, clothing shoes, and cables.

[0023] The present invention uses fumed silica as the main reinforcing filler. The main component of fumed silica is SiO2, and there are a large number of silanol groups (Si-OH) on its surface, which has a high surface energy and is prone to particle agglomeration. Therefore, the present invention uses chitosan to coat the fumed silica. Chitosan, as a natural polysaccharide, has good biocompatibility. Its molecular chain contains hydroxyl and amino groups, and these groups can interact with the hydroxyl groups on the surface of fumed silica through hydrogen bonds, electrostatic interactions or chemical bonds. For example, the hydroxyl and amino groups on the surface of chitosan can form hydrogen bonds with the hydroxyl groups on the surface of fumed silica, so that chitosan is coated on the surface of fumed silica. Further, the amino groups on the surface of chitosan can undergo a condensation reaction with the hydroxyl groups on the surface of fumed silica to form chemical bonds, further enhancing the coating effect of chitosan on fumed silica. The long-chain structure of chitosan coated on the surface of fumed silica can form a physical barrier on the surface of fumed silica, reducing the direct contact between particles, thereby improving the dispersibility of fumed silica, enhancing the dispersion effect of fumed silica, and reducing agglomeration.

[0024] In some embodiments, the average particle size of the fumed silica is 10 nm to 50 nm.

[0025] In some embodiments, the specific surface area of the fumed silica is 100 m 2 / g to 400 m 2 / g, and it has a relatively high porosity.

[0026] In some embodiments, the purity of the fumed silica is above 99.8%.

[0027] In some embodiments, the acid solution includes at least one of hydrochloric acid solution and sulfuric acid solution.

[0028] In some embodiments, the mass concentration of the acid solution is 0.1 M to 1 M.

[0029] In some embodiments, the mass concentration of the fumed silica solution is 1% to 10%.

[0030] In some embodiments, after the fumed silica is dispersed into the acid solution, it is ultrasonically treated for 10 min to 20 min to better disperse the fumed silica.

[0031] In some embodiments, chitosan is dissolved in a dilute acid solution to obtain a chitosan solution. The dilute acid solution includes at least one of hydrochloric acid solution and sulfuric acid solution. The concentration of the dilute acid solution is 0.1 M to 1 M, and the mass concentration of the chitosan solution is 1% to 10%.

[0032] In some embodiments, the mass ratio of chitosan to fumed silica is 1:1:5:1.

[0033] In some embodiments, it is stirred at 25°C to 50°C for 2 h to 4 h to ensure that the chitosan fully coats the fumed silica.

[0034] In some embodiments, the centrifugation speed is 5000 rpm to 10000 rpm, and the centrifugation time is 10 min to 20 min to prevent the quality of the encapsulated product from being damaged due to too long centrifugation time.

[0035] In the present invention, the encapsulated product of fumed silica coated with chitosan is used as the main reinforcing filler, and at the same time, magnesium hydroxide, raw rubber, cross-linking agent, vulcanizing agent and catalyst are supplemented and kneaded to obtain a silicone rubber with better comprehensive performance.

[0036] In the present invention, the addition of magnesium hydroxide can form a heat conduction path in the silicone rubber, improving the heat conduction performance and flame retardancy of the silicone rubber. Among them, the structure of the heat conduction path greatly affects the heat conduction effect of the silicone rubber.

[0037] In some embodiments, magnesium hydroxide includes magnesium hydroxide with large particle size and magnesium hydroxide with small particle size. The average particle size of the magnesium hydroxide with large particle size ranges from 5 μm to 20 μm, and the average particle size of the magnesium hydroxide with small particle size ranges from 0.1 μm to 2 μm. The interface between the magnesium hydroxide with large particle size and the silicone rubber is small and the thermal resistance is low, so the thermal conductivity is high. However, if the dosage of the magnesium hydroxide with large particle size is too high, it is difficult to form effective packing between particles, and it is also difficult to form a continuous heat conduction network. In this embodiment, the magnesium hydroxide with large and small particle sizes are mixed and packed. The magnesium hydroxide with small particle size can enter the voids that cannot be filled between the magnesium hydroxide with large particle size. The cooperation between the magnesium hydroxide with large particle size and the magnesium hydroxide with small particle size can form a tight packing, thereby generating more inter-particle contact points, increasing the number of heat conduction paths, effectively improving the thermal conductivity of the silicone rubber, reducing the thermal resistance. In addition, the mechanical properties of the silicone rubber can also be improved. The magnesium hydroxide with small particle size is beneficial to the mechanical strength, while the magnesium hydroxide with large particle size can reduce the viscosity of the silicone rubber system. Therefore, the compounding of the magnesium hydroxide with small particle size and the magnesium hydroxide with large particle size can optimize the properties of the silicone rubber including heat dissipation, mechanical properties and aging resistance.

[0038] In some embodiments, the mass of the magnesium hydroxide with large particle size is greater than or equal to the mass of the magnesium hydroxide with small particle size.

[0039] In some embodiments, the mass ratio of the magnesium hydroxide with large particle size to the magnesium hydroxide with small particle size is 1:1 to 3:1.

[0040] In some embodiments, the raw rubber includes at least one of methyl vinyl silicone rubber raw rubber and α,ω-dihydroxypolydimethylsiloxane.

[0041] In some embodiments, the raw rubber is α,ω-dihydroxypolydimethylsiloxane. α,ω-dihydroxypolydimethylsiloxane contains terminal hydroxyl groups and can react with the reinforcing filler fumed silica to form a Si-O-Si network structure, improving the heat resistance and weather resistance of the silicone rubber.

[0042] In some embodiments, the raw rubber is α,ω-dihydroxypolydimethylsiloxane, and the viscosity of α,ω-dihydroxypolydimethylsiloxane is 50000 cps to 60000 cps.

[0043] In some embodiments, the crosslinking agent includes trimethoxysilane.

[0044] In some embodiments, the vulcanizing agent includes at least one of bis(2,5-dimethyl-2,5-di(t-butylperoxy)hexane), bis(2,4-dichlorobenzoyl peroxide), and platinum vulcanizing agent.

[0045] In some embodiments, the catalyst includes dibutyltin dilaurate.

[0046] In some embodiments, the mass ratio of the coated product, magnesium hydroxide, raw rubber, crosslinking agent, vulcanizing agent, and catalyst is (5-20):(10-30):(40-60):(2-5):(1-3):(0.1-1).

[0047] In some embodiments, the temperature of the heat kneading is 100°C - 150°C, which is beneficial to promoting the uniform molding of the primary silicone rubber.

[0048] In step S30, 1-hydroxycyclohexyl phenyl ketone is dissolved in an organic solvent to obtain solution A, and then the initial silicone rubber is soaked in solution A for pretreatment of the initial silicone rubber, preparing for forming a surface layer on the surface of the initial rubber for subsequent crosslinking initiation. After the initial silicone rubber is soaked in solution A, it is then soaked in solution B. Under the irradiation of ultraviolet light, a hydrophilic surface can grow on the surface of the silicone rubber, thereby greatly improving the hydrophilic property of the silicone rubber. In addition, titanium dioxide is added to solution B in the present invention. The surface of titanium dioxide contains abundant hydroxyl groups, which can further improve the hydrophilic property of the silicone rubber. Moreover, titanium dioxide increases the surface hardness and wear resistance of the silicone rubber, can effectively improve the durability of the hydrophilic surface of the silicone rubber, long-term play the hydrophilic effect of the silicone rubber, and effectively improve the wet friction property of the silicone rubber.

[0049] In some embodiments, the organic solvent used to dissolve 1-hydroxycyclohexyl phenyl ketone in the organic solvent includes at least one of ethanol and acetone.

[0050] In some embodiments, the mass concentration of 1-hydroxycyclohexyl phenyl ketone in solution A is 5% - 10%.

[0051] In some embodiments, the range of the average particle size of titanium dioxide is 10nm - 50nm.

[0052] In some embodiments, the soaking time of the initial silicone rubber in solution A is 10min - 20min.

[0053] In some embodiments, the mass ratio of acrylic acid, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and titanium dioxide is (50-70):(5-20):(5-20).

[0054] In some embodiments, after acrylic acid, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and titanium dioxide are mixed, they are further stirred to promote uniform dispersion.

[0055] In some embodiments, the wavelength of the ultraviolet light is 395nm.

[0056] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not used to limit the present invention.

[0057] Example 1 The preparation method of the silicone rubber in Example 1 is as follows: S10: Dispersed fumed silica with an average particle size of 50 nm in 0.1 M hydrochloric acid solution to obtain a fumed silica solution with a mass fraction of 6%. Dispersed chitosan in 0.1 M hydrochloric acid solution to obtain a chitosan solution with a mass concentration of 6%. Mixed the fumed silica solution and the chitosan solution, and ensured that the mass ratio of chitosan to fumed silica was 1:1. Stirred at 50 °C for 3 h, centrifuged at a speed of 10000 rpm for 10 min, and obtained the coated product after washing and drying.

[0058] S20: Mixed the coated product, magnesium hydroxide, raw rubber α,ω-dihydroxypolydimethylsiloxane with a viscosity of 50000 cps - 60000 cps, crosslinking agent trimethoxysilane, vulcanizing agent bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and catalyst dibutyltin dilaurate according to the mass ratio of 20:30:50:4:3:0.5, heated and kneaded at 150 °C, and obtained the initial silicone rubber after evacuating. Among them, the magnesium hydroxide was small particle size magnesium hydroxide with an average particle size of 2 μm and large particle size magnesium hydroxide with an average particle size of 20 μm, and the mass ratio of small particle size magnesium hydroxide to large particle size magnesium hydroxide was 1:1.

[0059] S30: Dissolved 1-hydroxycyclohexyl phenyl ketone in an organic solvent to obtain solution A with a mass concentration of 5%. Mixed acrylic acid, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and titanium dioxide with a particle size range of 50 nm according to the mass ratio of 70:15:15 to obtain solution B. Immersed the initial silicone rubber in solution A, took it out and dried it, then immersed it in solution B, and carried out ultraviolet curing. The wavelength of the ultraviolet light was 395 nm, and then washed and dried to obtain the silicone rubber.

[0060] Example 2 The silicone rubber in Example 2 was prepared with reference to the preparation method of Example 1. The difference was that in step S10, the mass ratio of chitosan to fumed silica was 5:1.

[0061] Example 3 The silicone rubber in Example 3 was prepared with reference to the preparation method of Example 1. The difference was that in step S20, the coated product, magnesium hydroxide, raw rubber α,ω-dihydroxypolydimethylsiloxane with a viscosity of 50000 cps - 60000 cps, crosslinking agent trimethoxysilane, vulcanizing agent bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and catalyst dibutyltin dilaurate were mixed according to the mass ratio of 20:10:30:4:2:1.

[0062] Example 4 Example 4 The silicone rubber was prepared with reference to the preparation method of Example 1, except that in step S20, the mass ratio of small particle size magnesium hydroxide to large particle size magnesium hydroxide was 3:1.

[0063] Example 5 Example 5 The silicone rubber was prepared with reference to the preparation method of Example 1, except that in step S30, the mass ratio of acrylic acid, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and titanium dioxide was 70:20:20.

[0064] Example 6 Example 6 The silicone rubber was prepared with reference to the preparation method of Example 1, except that in step S20, all of the small particle size magnesium hydroxide was replaced with an equal mass of large particle size magnesium hydroxide.

[0065] Comparative Example 1 Comparative Example 1 The silicone rubber was prepared with reference to the preparation method of Example 1, except that the silicone rubber was not used to wrap the fumed silica with chitosan to prepare the wrapped product.

[0066] Comparative Example 2 Comparative Example 2 The silicone rubber was prepared with reference to the preparation method of Example 1, except that the preparation was stopped after obtaining the initial silicone rubber, and the operation of subsequent step S30 was not carried out.

[0067] Comparative Example 3 Comparative Example 3 The silicone rubber was prepared with reference to the preparation method of Example 1, except that in step S30, titanium dioxide was not added.

[0068] Performance Test 1. Test the thermal conductivity and tensile strength of the silicone rubbers of the examples and comparative examples.

[0069] 2. Test the wet friction coefficient of the silicone rubbers of the examples and comparative examples: (1) Test its wet friction coefficient in the presence of water and humidity; (2) Use the same force to rub the silicone rubber on a rough surface 100 times and then test its wet friction coefficient in the presence of water and humidity.

[0070] Table 1

[0071] It can be seen from the examples that the silicone rubber prepared by the present invention has good thermal conductivity and mechanical properties, and a large wet friction coefficient. Even after 100 times of friction, it can still maintain a high wet friction coefficient.

[0072] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. A preparation method of silicone rubber, characterized in that, It includes the following steps: S10: Disperse fumed silica in an acid solution to obtain a fumed silica solution, disperse chitosan in a dilute acid solution to obtain a chitosan solution, then mix the fumed silica solution and the chitosan solution, and obtain a coated product through stirring, centrifugation, washing, and drying; S20: Mix the coated product, magnesium hydroxide, raw rubber, crosslinking agent, vulcanizing agent, and catalyst, heat and knead, and obtain the initial silicone rubber after evacuating; S30: Dissolve 1-hydroxycyclohexyl phenyl ketone in an organic solvent to obtain solution A, mix acrylic acid, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and titanium dioxide to obtain solution B, soak the initial silicone rubber in solution A, take it out and dry it, then soak it in solution B, and perform ultraviolet curing, cleaning, and drying to obtain the silicone rubber.

2. The preparation method of the silicone rubber according to claim 1, wherein The average particle size of the fumed silica ranges from 10 nm to 50 nm.

3. The preparation method of the silicone rubber according to claim 1, wherein, In the step of heat kneading, the heating temperature is 100°C to 150°C.

4. The preparation method of the silicone rubber according to claim 1, wherein The magnesium hydroxide includes small particle size magnesium hydroxide and large particle size magnesium hydroxide. The average particle size of the small particle size magnesium hydroxide is 0.1 μm to 2 μm, and the average particle size of the large particle size magnesium hydroxide is 5 μm to 20 μm.

5. The preparation method of the silicone rubber according to claim 1, wherein The raw rubber includes at least one of methyl vinyl silicone rubber raw rubber and α,ω-dihydroxypolydimethylsiloxane.

6. The preparation method of the silicone rubber according to claim 5, characterized in that, The raw rubber is α,ω-dihydroxypolydimethylsiloxane, and the viscosity of the α,ω-dihydroxypolydimethylsiloxane is 50000 cps to 60000 cps.

7. The preparation method of the silicone rubber according to claim 1, characterized in that, The crosslinking agent includes trimethoxysilane; and / or, the catalyst includes dibutyltin dilaurate; and / or, the vulcanizing agent includes at least one of bis(2,5-dimethyl-2,5-di(t-butylperoxy)hexane), bis(2,4-dichlorobenzoyl) peroxide, and platinum vulcanizing agent.

8. The preparation method of the silicone rubber according to claim 1, wherein, The mass ratio of the coated product, magnesium hydroxide, raw rubber, crosslinking agent, vulcanizing agent, and catalyst is (5 - 20):(10 - 30):(40 - 60):(2 - 5):(1 - 3):(0.1 - 1).

9. The preparation method of the silicone rubber according to claim 1, characterized in that, The mass ratio of acrylic acid, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and titanium dioxide is (50 - 70):(5 - 20):(5 - 20).

10. A silicone rubber, characterized in that, The silicone rubber is prepared by the preparation method described in any one of claims 1 to 9.

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