High-compression-strength surface hydrophobic silicone rubber foam and preparation method thereof

Abstract

The invention relates to the technical field of silicone rubber foam materials, in particular to high-compression-strength surface hydrophobic silicone rubber foam and a preparation method thereof. The high-compression-strength surface hydrophobic silicone rubber foam comprises the following substances in parts by weight: 300-500 parts of heat vulcanized silicone rubber and 2-8 parts of a hydrophobic modifier, 0.1 to 1.0 part of a photoinitiator; the hydrophobic modifier comprises a compound with a sulfydryl group and a compound with a hydrophobic group. According to the technical scheme, the components of the surface hydrophobic silicone rubber foam are optimized, the heat vulcanized silicone rubber provides necessary mechanical strength and durability, and the hydrophobic modifier obtains a hydrophobic or hydrophilic surface on the surface of a polymer through a simple mercaptan-ene click reaction; the method has the advantages of simple preparation process, high selectivity, no by-product, mild reaction conditions and short reaction time, meets the requirements of industrial production, and is beneficial to application in production practice.

Description

Technical Field

[0001] The invention relates to the technical field of silicone rubber foam materials, in particular to a high-compression-strength surface-hydrophobic silicone rubber foam and a preparation method thereof. Background Art

[0002] Silicone rubber foam is a silicone-based foam material that is widely used in many fields due to its unique physical and chemical properties. Compared with conventional foam materials, silicone rubber foam can recover its original shape to a large extent, so it excels in applications such as shock absorption, sound insulation and sealing. Its low density and lightweight properties enable weight reduction in many applications, thereby improving efficiency.

[0003] However, the existing silicone rubber foam materials have poor surface hydrophobicity, and materials with special wettability play an important role in liquid transportation, coatings, waterproofing, construction and medical fields. Superhydrophobic materials are often used in the fields of surface anti-fogging, self-cleaning, drag reduction, anti-icing, corrosion resistance, etc. Therefore, improving the hydrophobicity of silicone rubber foam materials can further expand the scope of use of silicone rubber foam materials.

[0004] The existing hydrophobic modification of silicone rubber surface usually enhances the hydrophobic effect of the material by roughening its surface or introducing low surface energy materials on the microstructure surface. The main methods include physical deposition, chemical etching, spraying, etc. However, the materials prepared by the above technical solutions are easy to reduce the compressive strength and mechanical properties of silicone rubber foam. At the same time, the overall production process is complicated and the production time is long. It cannot be prepared and used on a large scale, which greatly limits its scope of application. Summary of the invention

[0005] Based on the technical problems existing in the above-mentioned prior art, the present invention provides a high compressive strength surface hydrophobic silicone rubber foam and a preparation method thereof.

[0006] In the first aspect, the present application provides a high compressive strength surface hydrophobic silicone rubber foam, which adopts the following technical solution: A high compressive strength surface hydrophobic silicone rubber foam comprises the following materials in parts by weight: 300-500 parts of heat-cured silicone rubber; 2-8 parts of hydrophobic modifier; Photoinitiator 0.1-1.0 part; The hydrophobic modifier includes a compound having both a mercapto group and a hydrophobic group.

[0007] Through the above technical scheme, the technical scheme of this application optimizes the components of the surface hydrophobic silicone rubber foam. The heat-vulcanized silicone rubber provides the necessary mechanical strength and durability, and the addition of the hydrophobic modifier is intended to improve the surface properties of the foam so that it has excellent hydrophobicity. This hydrophobicity can prevent the adsorption of water, thereby improving the service life and applicability of the foam. The addition of the photoinitiator is to promote the chemical reaction of the hydrophobic modifier through photopolymerization in the subsequent production process to form a stable hydrophobic coating. Overall, the design emphasizes the relationship between the structure and performance of the material, laying the foundation for the development of high-performance silicone rubber foam.

[0008] Furthermore, the compound having both a thiol group and a hydrophobic group is a fluorine-containing thiol or an alkyl thiol, and the fluorine-containing thiol includes at least one of 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexanethiol, 1H,1H,2H,2H-perfluorohexanethiol, 1H,1H,2H,2H-perfluoropentanethiol, 4,4,5,5,5-pentafluoropentanethiol, 1H,1H,2H,2H-perfluorodecanethiol, perfluorohexylethylthiol, and perfluorooctanethiol; the alkyl thiol has a carbon chain length of 10 to 20, and the alkyl thiol with a carbon chain length of 10 to 20 includes at least one of hexadecanethiol and lauryl mercaptan.

[0009] Through the above technical scheme, the technical scheme of the present application optimizes the components of the compound with a thiol group, wherein the special molecular structure of the fluorinated mercaptan can significantly improve the hydrophobicity of the material. The alkyl mercaptan with a carbon chain length of 10 to 20 and a longer carbon chain structure help to improve the hydrophobicity of the material and form a stable hydrophobic layer, thereby effectively preventing the penetration of water. The present application uses fluorinated mercaptan or alkyl mercaptan to form a chemical bond with the double bond of silicone rubber, thereby enhancing the adhesion of the hydrophobic layer, reducing the surface energy, and forming a larger contact angle when it contacts water, thereby achieving excellent hydrophobic properties.

[0010] Furthermore, the heat-vulcanized silicone rubber is prepared by stacking a plurality of silicone rubber resin substrates alternately and then molding them into sheets, and the silicone rubber resin substrate includes the following weight substances: Vinyl silicone rubber 100 parts; 25-45 parts of white carbon black; 1-8 parts of structural modifier; 1-3 parts of vulcanizing agent.

[0011] Through the above technical scheme, the technical scheme of the present application defines the composition of heat-vulcanized silicone rubber, including vinyl silicone rubber, white carbon black, structural modifier and vulcanizing agent. Among them, the present application optimizes the composition of heat-vulcanized silicone rubber, and prepares it by alternately stacking a variety of silicone rubber resin substrates and then molding them into sheets. On the one hand, after silicone rubbers of different formulations are alternately stacked, the pore volumes of foamed molded products of different formulations are different. Silicone rubber with small pore structure can effectively improve the compression strength of heat-vulcanized rubber, and silicone rubber with larger pores can reduce the overall density of the material, so that the prepared silicone rubber can provide good mechanical strength and excellent lightweight performance, and white carbon black as a filler enhances the strength and toughness of the material. The structural modifier can improve the rheological properties of silicone rubber and enhance its processability. The vulcanizer improves the heat resistance and mechanical properties of the material through cross-linking reactions.

[0012] Furthermore, the content of the structure modifier contained in each silicone rubber resin substrate is different.

[0013] Furthermore, the structure modifier includes at least one of hydroxy silicone oil, methyl silicone oil, terminal hydroxymethylphenyl silicone oil, diphenylsilanediol, and silazane.

[0014] Through the above technical scheme, the technical scheme of the present application selects structural modifier materials of different qualities to improve the internal structure and pore volume of the prepared heat-vulcanized silicone rubber, thereby making it have excellent mechanical strength and good lightweight performance.

[0015] Further, the photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,2-carboxymethylpropionic acid, 2,2-dimethoxy-2-phenylacetophenone, benzophenone, thioxanthone, camphorquinone or azobisisobutyronitrile.

[0016] Furthermore, the vulcanizing agent includes at least one of DCP, DBPMH, BP, DCBP, TBPB, and BIPB.

[0017] Furthermore, the heat-vulcanized silicone rubber is made by the following scheme: According to different structural modifier formulas, at least two portions of vinyl silicone rubber, white carbon black, and structural modifier are mixed and placed in a mixing device for mixing; after the mixing is completed, a vulcanizing agent is added and placed in a mixing device for back mixing at room temperature to prepare at least two mixed rubbers; The heat-vulcanized silicone rubber can be prepared by stacking at least two different mixed rubbers alternately, molding them, and vulcanizing them.

[0018] Through the above technical scheme, the technical scheme of the present application is prepared by alternately stacking a variety of silicone rubber resin substrates and then molding them into sheets. On the one hand, after silicone rubbers of different formulations are alternately stacked, the pore volumes of foamed molded products of different formulations are different. Silicone rubber with small pore structure can effectively improve the compressive strength of heat-vulcanized rubber, and silicone rubber with larger pores can reduce the overall density of the material, so that the prepared silicone rubber can provide good mechanical strength and excellent lightweight performance.

[0019] In the second aspect, the technical solution of the present application provides a method for preparing a high compressive strength surface hydrophobic silicone rubber foam, using the following technical solution: A method for preparing a high compressive strength surface hydrophobic silicone rubber foam comprises the following preparation steps: A hydrophobic modifier and a photoinitiator are mixed and placed in a solvent to prepare a coating liquid; The coating liquid is applied to the surface of the heat-vulcanized silicone rubber, dried at room temperature, irradiated with ultraviolet light, and after the photopolymerization is completed, washed and collected to obtain a surface hydrophobic modified film; The surface hydrophobic modified film is placed in a high-pressure device, subjected to supercritical foaming treatment, heated and vacuum vulcanized, and the high compressive strength surface hydrophobic silicone rubber foam can be prepared.

[0020] Through the above technical scheme, the technical scheme of the present application first prepares the coating liquid and applies it on the surface of the silicone rubber, realizes the photopolymerization reaction by ultraviolet light irradiation, forms a hydrophobic modified film, and finally obtains the desired foam by supercritical foaming treatment and vacuum vulcanization. Since the hot-vulcanized silicone rubber used in this application is obtained by stacking silicone rubber sheets obtained from different formulas and then molding and vulcanizing them, different pore structures are obtained after supercritical foaming, which enhances the compression performance of the material. This is because the structure of the small pores in the structure can provide high support during the compression process, thereby obtaining better compression performance than the silicone rubber foam with a large pore structure, and the larger part of the pores can provide the foam material with a low density. The combination of physical and chemical methods in the technical scheme of the present application improves the foam structure and its performance through supercritical technology.

[0021] Furthermore, the solvent includes at least one of ethanol, methanol, acetonitrile, acetone, dimethyl sulfoxide, tetrahydrofuran, toluene, ethyl acetate, dichloromethane, chloroform, trifluoroethanol, N,N-dimethylformamide or N,N-dimethylacetamide.

[0022] In summary, this application has the following beneficial effects: First, the technical solution of this application optimizes the components of the surface hydrophobic silicone rubber foam. The heat-vulcanized silicone rubber provides the necessary mechanical strength and durability, and the addition of the hydrophobic modifier is intended to improve the surface properties of the foam, making it have excellent hydrophobicity. This hydrophobicity can prevent the adsorption of water, thereby improving the service life and applicability of the foam. The addition of the photoinitiator is to promote the chemical reaction of the hydrophobic modifier through photopolymerization in the subsequent production process to form a stable hydrophobic coating. Overall, the design of this claim emphasizes the relationship between the structure and performance of the material, laying the foundation for the development of high-performance silicone rubber foam.

[0023] Second, the technical solution of this application optimizes the components of compounds with thiol and hydrophobic groups. The fluorine-containing compounds are selected because of their special molecular structure, which can significantly improve the hydrophobic properties of the material; and the alkylthiols with a carbon chain length of 10 to 20, the longer carbon chain structure helps to improve the hydrophobicity of the material and form a stable hydrophobic layer, thereby effectively preventing the penetration of water. The thiol group reacts chemically with the double bond of the silicone rubber to form a strong chemical connection, thereby improving the adhesion and stability of the modifier. The introduction of this compound not only enhances the hydrophobicity of the foam, but also improves its chemical resistance and weather resistance. DETAILED DESCRIPTION

[0024] The present application is further described in detail below with reference to the embodiments.

[0025] In the examples of the present application, the raw materials and instruments used are as follows, but not limited thereto. Raw materials not otherwise specified are of analytical grade.

[0026] Preparation Example 1 Heat vulcanized silicone rubber1 100 parts of methyl vinyl silicone rubber, 40 parts of fumed silica and 4.5 parts of hydroxy silicone oil were added into a rubber internal mixer at 105°C and mixed evenly. The mixture was discharged after mixing for 30 minutes, allowed to stand and cool, and then placed in the internal mixer for back-mixing at room temperature for 10 minutes. 1 part of DCP was added and mixed for 15 minutes to prepare a mixed rubber material A.

[0027] 100 parts of methyl vinyl silicone rubber, 40 parts of fumed silica and 1.2 parts of hydroxy silicone oil were added into a rubber internal mixer at 105°C and mixed evenly. The material was discharged after mixing for 30 minutes, allowed to stand and cool, and then back-mixed in the internal mixer at room temperature for 10 minutes. 1 part of DCP was added and mixed for 15 minutes to prepare a mixed rubber material B.

[0028] Rubber materials A and B were extruded into films with a thickness of 0.3 mm respectively, and then films A and B were alternately stacked in ten layers in turn, placed on a vulcanizer for molding, and the vulcanization temperature was controlled to be 125° C. and the pressure was 10 MPa. After molding for 5 minutes, a heat-vulcanized silicone rubber film 1 was prepared.

[0029] Preparation Example 2 Heat vulcanized silicone rubber 2 The preparation method of the mixed rubber material is consistent with the overlapping method and the heat-vulcanized silicone rubber 1. The difference is that the overlapped sheets are subjected to the vulcanization temperature of 125°C, the pressure of 10 MPa, and the molding time of 5.5 min to prepare the heat-vulcanized silicone rubber sheet 2.

[0030] Example 1 A high compression strength surface hydrophobic silicone rubber foam comprises 300-500 parts of a heat-vulcanized silicone rubber film 1, 4 parts of perfluorodeoxythiophene and 0.4 parts of benzophenone.

[0031] A method for preparing a high-compression-strength surface-hydrophobic silicone rubber foam comprises the following preparation steps: 4 parts of perfluorodeoxythiol and 0.4 parts of benzophenone were mixed in 12 parts of ethanol to prepare a coating solution.

[0032] The coating solution was evenly coated on the surface of the heat-cured silicone rubber film 1. After the solvent evaporated at room temperature, the UV intensity was 2500 mW / cm 2 The film was irradiated with ultraviolet light for 5 minutes to fully react, and the photoinitiator and a small amount of surface modifier remaining on the film surface were washed away with ethanol. After the solvent was evaporated, a heat-vulcanized silicone rubber film 1 with a hydrophobic surface modification was obtained.

[0033] The surface hydrophobic modified heat-cured silicone rubber film 1 is placed in an autoclave, and the gas in the autoclave is replaced with nitrogen / carbon dioxide, and then filled with high-pressure nitrogen / carbon dioxide, and immersed at 50°C and 16Mpa for 2 hours; then the pressure is quickly released to zero. The foamed sample is placed in a vacuum oven at 170°C for vulcanization for 1 hour, and then the temperature is raised to 200°C for further treatment for 2 hours, and a high compressive strength surface hydrophobic silicone rubber foam can be prepared.

[0034] Example 2 A high compression strength surface hydrophobic silicone rubber foam comprises 300-500 parts of a heat-vulcanized silicone rubber film 1, 4 parts of lauryl mercaptan and 0.8 parts of benzophenone.

[0035] A method for preparing a high-compression-strength surface-hydrophobic silicone rubber foam comprises the following preparation steps: 4 parts of lauryl mercaptan and 0.8 parts of benzophenone were mixed in 12 parts of ethanol to prepare a coating solution.

[0036] The coating solution was evenly coated on the surface of the heat-cured silicone rubber film 1. After the solvent evaporated at room temperature, the UV intensity was 2500 mW / cm 2 The film was irradiated with ultraviolet light for 5 minutes to fully react, and the photoinitiator and a small amount of surface modifier remaining on the film surface were washed away with ethanol. After the solvent was evaporated, a heat-vulcanized silicone rubber film 1 with a hydrophobic surface modification was obtained.

[0037] The surface hydrophobic modified heat-cured silicone rubber film 1 is placed in an autoclave, and the gas in the autoclave is replaced with nitrogen / carbon dioxide, and then filled with high-pressure nitrogen / carbon dioxide, and immersed at 50°C and 16Mpa for 2 hours; then the pressure is quickly released to zero. The foamed sample is placed in a vacuum oven at 170°C for vulcanization for 1 hour, and then the temperature is raised to 200°C for further treatment for 2 hours, and a high compressive strength surface hydrophobic silicone rubber foam can be prepared.

[0038] Comparative Example 1 A high compression strength surface hydrophobic silicone rubber foam comprises 300-500 parts of 1 heat-cured silicone rubber film, 2 parts of perfluorodeoxythiophene and 0.4 parts of benzophenone.

[0039] A method for preparing a high-compression-strength surface-hydrophobic silicone rubber foam comprises the following preparation steps: 2 parts of perfluorodeoxythiol and 0.4 parts of benzophenone were mixed in 12 parts of ethanol to prepare a coating solution.

[0040] The coating solution was evenly coated on the surface of the heat-cured silicone rubber film 1. After the solvent evaporated at room temperature, the UV intensity was 2500 mW / cm 2 The film was irradiated with ultraviolet light for 5 minutes to fully react, and the photoinitiator and a small amount of surface modifier remaining on the film surface were washed away with ethanol. After the solvent was evaporated, a heat-vulcanized silicone rubber film 1 with a hydrophobic surface modification was obtained.

[0041] The surface hydrophobic modified heat-cured silicone rubber film 1 is placed in an autoclave, and the gas in the autoclave is replaced with nitrogen / carbon dioxide, and then filled with high-pressure nitrogen / carbon dioxide, and immersed at 50°C and 16Mpa for 2 hours; then the pressure is quickly released to zero. The foamed sample is placed in a vacuum oven at 170°C for vulcanization for 1 hour, and then the temperature is raised to 200°C for further treatment for 2 hours, and a high compressive strength surface hydrophobic silicone rubber foam can be prepared.

[0042] Comparative Example 2 A high compression strength surface hydrophobic silicone rubber foam comprises 300-500 parts of a heat-vulcanized silicone rubber film 1 and 0.4 parts of benzophenone.

[0043] A method for preparing a high-compression-strength surface-hydrophobic silicone rubber foam comprises the following preparation steps: A coating solution was prepared by mixing 0.4 parts of benzophenone in 12 parts of ethanol.

[0044] The coating solution was evenly coated on the surface of the heat-cured silicone rubber film 2, and the UV intensity was 2500 mW / cm after the solvent evaporated at room temperature. 2 The film was irradiated with ultraviolet light for 5 minutes, and the photoinitiator and a small amount of surface modifier remaining on the surface of the film were washed away with ethanol. After the solvent was evaporated, a heat-vulcanized silicone rubber film 2 with a hydrophobic surface modification was obtained.

[0045] The surface hydrophobic modified heat-cured silicone rubber film 1 is placed in an autoclave, and the gas in the autoclave is replaced with nitrogen / carbon dioxide, and then filled with high-pressure nitrogen / carbon dioxide, and immersed at 50°C and 16Mpa for 2 hours; then the pressure is quickly released to zero. The foamed sample is placed in a vacuum oven at 170°C for vulcanization for 1 hour, and then the temperature is raised to 200°C for further treatment for 2 hours, and a high compressive strength surface hydrophobic silicone rubber foam can be prepared.

[0046] Comparative Example 3 Compared with Example 1, this comparative example 3 adopts the following scheme to prepare a heat-vulcanized silicone rubber film, and the remaining steps are the same as those of Example 1.

[0047] 100 parts of methyl vinyl silicone rubber, 40 parts of fumed silica and 4.5 parts of hydroxy silicone oil were added into a rubber internal mixer at 105°C and mixed evenly. The mixture was discharged after mixing for 30 minutes, allowed to stand and cool, and then placed in the internal mixer for back-mixing at room temperature for 10 minutes. 2 parts of DCP were added and mixed for 15 minutes, and then placed on a vulcanizer for molding. The vulcanization temperature was controlled to be 125°C and the pressure to be 10 MPa. After molding for 5 minutes, a hot-vulcanized silicone rubber sheet was prepared.

[0048] Comparative Example 4 Compared with Comparative Example 3, Comparative Example 3 of the present application uses the heat-vulcanized silicone rubber film prepared in Comparative Example 3 to prepare the silicone rubber foam material, and the specific steps are as follows: The pre-cured rubber sheet prepared in the same manner as in Comparative Example 3 was placed in an autoclave, and the gas in the autoclave was replaced with nitrogen / carbon dioxide, and then filled with high-pressure nitrogen / carbon dioxide, and immersed at 50°C and 16Mpa for 2 hours; then the pressure was quickly released to zero. The foamed sample was placed in a vacuum oven at 170°C for vulcanization for 1 hour, and then the temperature was raised to 200°C for further treatment for 2 hours, and a high compressive strength surface hydrophobic silicone rubber foam was prepared.

[0049] Comparative Example 5 A high compression strength surface hydrophobic silicone rubber foam comprises 300-500 parts of a heat-cured silicone rubber film 2, 4 parts of perfluorodeoxythiophene and 0.4 parts of benzophenone.

[0050] A method for preparing a high-compression-strength surface-hydrophobic silicone rubber foam comprises the following preparation steps: 4 parts of perfluorodeoxythiol and 0.4 parts of benzophenone were dissolved in 12 parts of ethanol to prepare a coating solution.

[0051] The coating solution was evenly coated on the surface of the heat-cured silicone rubber film 2, and the UV intensity was 2500 mW / cm after the solvent evaporated at room temperature. 2 The film was irradiated with ultraviolet light for 5 minutes to fully react, and the photoinitiator remaining on the surface of the film that did not participate in the reaction was washed away with ethanol. After the solvent was evaporated, a heat-vulcanized silicone rubber film 2 with a hydrophobic surface modification was obtained.

[0052] The surface hydrophobic modified heat-cured silicone rubber film 1 is placed in an autoclave, and the gas in the autoclave is replaced with nitrogen / carbon dioxide, and then filled with high-pressure nitrogen / carbon dioxide, and immersed at 50°C and 16Mpa for 2 hours; then the pressure is quickly released to zero. The foamed sample is placed in a vacuum oven at 170°C for vulcanization for 1 hour, and then the temperature is raised to 200°C for further treatment for 2 hours, and a high compressive strength surface hydrophobic silicone rubber foam can be prepared.

[0053] Performance Testing The silicone rubber foams prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to performance testing: Compression strength: The compression test was conducted according to ASTM D 1056, with a compression of 25%.

[0054] The results are shown in Table 1 below: Table 1 Performance test table

[0055] From the above examples 1, 2 and comparative examples 1-5, combined with the test results of Table 1, it can be found that after the pre-cured silicone rubber sheet is coated with a hydrophobic modifier and a catalyst, the silicone rubber foam material can show more significant hydrophobic properties than the silicone rubber foam material without surface hydrophobic modification through photocatalytic reaction, foaming and secondary vulcanization. It is found through example 1 and comparative example 3 that the compression properties of silicone rubber foam can be greatly improved by alternately laminating silicone rubbers of different formulations, performing molded pre-vulcanization treatment and then foaming.

[0056] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0057] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0058] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0059] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

Claims

1. A high compressive strength surface hydrophobic silicone rubber foam, characterized in that: The composition includes the following materials in parts by weight: 300-500 parts of heat-cured silicone rubber; 2-8 parts of hydrophobic modifier; Photoinitiator 0.1-1.0 part; The hydrophobic modifier includes a compound having a mercapto group and a compound having a hydrophobic group.

2. The high compressive strength surface hydrophobic silicone rubber foam according to claim 1, characterized in that: The compound with a thiol group is a fluorine-containing thiol or an alkyl thiol, and the fluorine-containing thiol includes at least one of 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexanethiol, 1H,1H,2H,2H-perfluorohexanethiol, 1H,1H,2H,2H-perfluoropentanethiol, 4,4,5,5,5-pentafluoropentanethiol, 1H,1H,2H,2H-perfluorodecanethiol, perfluorohexylethylthiol, and perfluorooctanethiol; the carbon chain length of the alkyl thiol is 10 to 20, and the alkyl thiol with a carbon chain length of 10 to 20 includes at least one of hexadecanethiol and lauryl mercaptan.

3. The high compressive strength surface hydrophobic silicone rubber foam according to claim 1, characterized in that: The heat-vulcanized silicone rubber is prepared by stacking a plurality of silicone rubber resin substrates alternately and then molding them into sheets. The silicone rubber resin substrate includes the following materials by weight: Vinyl silicone rubber 100 parts; 25-45 parts of white carbon black; 1-8 parts of structural modifier; 1-3 parts of vulcanizing agent.

4. The high compressive strength surface hydrophobic silicone rubber foam according to claim 3, characterized in that: The content of the structure modifier contained in each of the silicone rubber resin substrates is different.

5. The high compressive strength surface hydrophobic silicone rubber foam according to claim 3, characterized in that: The structure modifier includes at least one of hydroxy silicone oil, methyl silicone oil, terminal hydroxy methyl phenyl silicone oil, diphenylsilane diol and silazane.

6. The high compressive strength surface hydrophobic silicone rubber foam according to claim 3, characterized in that: The vulcanizing agent includes at least one of DCP, DBPMH, BP, DCBP, TBPB, and BIPB.

7. The high compressive strength surface hydrophobic silicone rubber foam according to claim 1, characterized in that: The photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,2-carboxymethylpropionic acid, 2,2-dimethoxy-2-phenylacetophenone, benzophenone, thioxanthone, camphorquinone or azobisisobutyronitrile.

8. The high compressive strength surface hydrophobic silicone rubber foam according to claim 3, characterized in that: The heat-vulcanized silicone rubber is made by the following scheme: According to different structural modifier formulas, at least two portions of vinyl silicone rubber, white carbon black, and structural modifier are mixed and placed in a mixing device for mixing; after the mixing is completed, a vulcanizing agent is added and placed in a mixing device for back mixing at room temperature to prepare at least two mixed rubbers; The heat-vulcanized silicone rubber can be prepared by stacking at least two different mixed rubbers alternately, molding them, and vulcanizing them.

9. A method for preparing a high compressive strength surface hydrophobic silicone rubber foam according to any one of claims 1 to 8, characterized in that: The method comprises the following preparation steps: A hydrophobic modifier and a photoinitiator are mixed and placed in a solvent to prepare a coating liquid; The coating liquid is applied to the surface of the heat-vulcanized silicone rubber, dried at room temperature, irradiated with ultraviolet light, and after the photopolymerization is completed, washed and collected to obtain a surface hydrophobic modified film; The surface hydrophobic modified film is placed in a high-pressure device, subjected to supercritical foaming treatment, heated and vacuum vulcanized, and the high compressive strength surface hydrophobic silicone rubber foam can be prepared.

10. The method for preparing a high compressive strength surface hydrophobic silicone rubber foam according to claim 9, characterized in that: The solvent includes at least one of ethanol, methanol, acetonitrile, acetone, dimethyl sulfoxide, tetrahydrofuran, toluene, ethyl acetate, dichloromethane, chloroform, trifluoroethanol, N,N-dimethylformamide or N,N-dimethylacetamide.

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