Highly transparent silicone rubber material and method for producing the same

Abstract

The application provides a high-transparency silicone rubber material and a preparation method thereof. The silicone rubber material comprises the following raw materials in parts by mass: 100 parts of methyl vinyl phenyl rubber, 10-30 parts of modified white carbon black, 3-5 parts of vinyl MQ silicone resin, 4-6 parts of polymethyl hydrogen siloxane, 1-1.5 parts of vinyl hydroxyl silicone oil and 0.001-0.003 parts of platinum catalyst. The modified white carbon black is obtained by grafting benzotriazole silane coupling agent and silicone oil onto the modified white carbon black. The benzotriazole silane coupling agent is obtained by urethane reaction of hydroxy benzotriazole compound and isocyanate silane coupling agent. The silicone oil grafting silane coupling agent is obtained by addition reaction of hydrogen-terminated polydimethylsiloxane and vinyl silane coupling agent. The silicone rubber material has good transparency and light stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone rubber, in particular to a high-transparency silicone rubber material and a preparation method thereof. BACKGROUND

[0002] Silicone rubber is widely used in optoelectronic devices, LED packaging, medical consumables, transparent structural parts and other fields with high requirements for optical performance and long-term reliability due to its excellent heat resistance, electrical insulation, flexibility and chemical stability. For the above applications, in addition to basic mechanical properties, the material is also required to have high transparency and good light stability. However, there are many factors affecting the transparency and optical stability of silicone rubber, including filler particle size and agglomeration degree, filler / matrix refractive index difference, interface compatibility, white carbon black water absorption, and slight yellowing under light. Therefore, the preparation of high-transparency silicone rubber has always been the focus of industry research.

[0003] Existing transparent silicone rubber usually improves transparency by reducing filler aggregation, improving filler and silicone rubber interface compatibility, and optimizing crosslinking structure. For example, CN114686001A reduces light scattering caused by water absorption by improving the hydrophobicity of precipitated white carbon black; CN116396619A adjusts the reinforcing structure to balance transparency and mechanical properties; CN116987389A focuses on improving the dispersion state of white carbon black to improve the light transmittance. The above technical solutions have improved the optical properties of transparent silicone rubber to some extent.

[0004] However, the existing technology still has the following deficiencies, for example, white carbon black, as a commonly used reinforcing filler in transparent silicone rubber, has a high surface hydroxyl density and strong adsorption, which makes it easy to agglomerate, and even if surface treatment is performed, uneven treatment may occur, resulting in mismatch between the local refractive index of the filler and the silicone rubber matrix, producing light scattering points and limiting the transparency of the material. In addition, the siloxane main chain is prone to free radical reaction under ultraviolet light or high-energy visible light (such as blue light), causing changes in crosslinking structure, which may cause slight yellowing or decrease in light transmittance. The existing technology uses conventional antioxidants or simple coating measures to reduce the influence of such light, but the long-term light stability is limited, and the transparency still decreases under long-term light.

[0005] In summary, although the existing technology has improved transparent silicone rubber from the aspects of filler treatment, dispersion optimization and formulation control, there are still deficiencies in further improving transparency, improving light stability and maintaining long-term optical performance. Therefore, a silicone rubber material that can simultaneously achieve high transparency and excellent light stability is needed. SUMMARY

[0006] The application provides a high-transparency silicone rubber material and a preparation method thereof, and aims to solve the technical problems of low transparency, unstable filler interface, easy yellowing under light, and insufficient long-term optical performance retention in existing transparent silicone rubber.

[0007] In a first aspect, the application provides a high-transparency silicone rubber material, which comprises the following raw materials by mass:

[0008] 100 parts of methyl vinyl phenyl rubber, 10-30 parts of modified white carbon black, 3-5 parts of vinyl MQ silicone resin, 4-6 parts of polymethyl hydrogen siloxane, 1-1.5 parts of vinyl hydroxyl silicone oil, and 0.001-0.003 parts of platinum catalyst.

[0009] The modified white carbon black is obtained by grafting a benzotriazole silane coupling agent and a silicone oil onto the modified white carbon black; the benzotriazole silane coupling agent is obtained by urethane reaction of a hydroxybenzotriazole compound and an isocyanate silane coupling agent; and the silicone oil grafting silane coupling agent is obtained by addition reaction of hydrogen-terminated polydimethylsiloxane and a vinyl silane coupling agent.

[0010] According to the application, the modified interface layer constructed by introducing a benzotriazole silane coupling agent and a silicone oil onto the surface of the white carbon black can significantly improve the dispersibility and interface stability of the filler in the silicone rubber matrix, thereby effectively reducing the interface refractive index difference and light scattering caused by filler aggregation, and realizing the high transparency of the silicone rubber material. Meanwhile, the benzotriazole structure can reduce the structural changes caused by the interface light excitation reaction under light, so that the optical retention and yellowing inhibition ability of the material under long-term light are improved.

[0011] Specifically, methyl vinyl phenyl rubber as a silicone rubber matrix provides good transparency and basic mechanical properties for the material; modified white carbon black as a reinforcing phase, in which the benzotriazole silane coupling agent forms a stable light absorption and energy dissipation layer on the surface of the white carbon black, the benzotriazole structure has higher interfacial compatibility with the siloxane matrix, and it is not easy to form a polar enrichment area on the surface of the white carbon black, so it is more conducive to maintaining the uniformity of the interfacial refractive index; in addition, the benzotriazole structure will not have adverse interactions with the platinum catalyst in the addition curing system, which can ensure that the crosslinking reaction proceeds uniformly; the light absorption and energy dissipation of benzotriazole can also inhibit the generation of trace radicals at the filler-matrix interface under light conditions, so that the material can maintain higher optical stability under blue light or ultraviolet light irradiation; the siloxane flexible segment introduced by the silicone oil grafted silane coupling agent has similar chemical composition and refractive index with the silicone rubber matrix, which can construct a flexible compatible layer, improve the spreading property and interfacial coverage of the filler during the mixing process; the synergistic effect of the two types of silane coupling agents makes the filler surface form a composite structure of “rigid light stabilization layer + flexible matching layer”, which on the one hand realizes the deep passivation of the hydroxyl group on the surface of the white carbon black, reduces the light scattering caused by the polarity difference; on the other hand, the smooth transition of the refractive index gradient improves the interfacial optical consistency, thereby significantly improving the light transmittance and transparency of the material. The composite interface structure can also improve the interfacial crosslinking uniformity during addition curing, avoid the formation of micro scattering points caused by local crosslinking density difference, and make the material maintain higher optical uniformity and transparency.

[0012] In addition, it is worth noting that although benzotriazole compounds have strong coordination ability in the free state, affecting the catalytic action of Karstedt type platinum catalyst, in this application, the benzotriazole modified white carbon black still has good curing; the reason may be that the benzotriazole group is connected to the silane coupling agent molecule by a carbamate bond and is further fixed on the surface of the white carbon black by hydrolysis and condensation, its coordination electron density is significantly reduced, and the interface layer composed of siloxane bonds is spatially separated from the continuous phase of the silicone rubber where the platinum catalyst is located, and it is not a free compound, plus the flexible PDMS interface layer constructed by the silicone oil grafted silane coupling agent on the surface of the white carbon black further blocks the direct contact between benzotriazole and the catalyst, so the modified white carbon black in this application can improve the long-lasting transparency while maintaining good curing level.

[0013] Vinyl MQ silicone resin can form a uniform network reinforcing structure with the silicone rubber matrix, which improves the mechanical properties of the material without significantly affecting the transparency; polymethylhydrogen siloxane as an addition crosslinking agent enables the material to form a three-dimensional crosslinked network through addition reaction; vinyl hydroxyl silicone oil helps to adjust the rheological properties and crosslinking uniformity of the system; platinum catalyst is used to promote the addition reaction of vinyl and Si-H, so that the curing process is fast and uniform. The synergistic effect between the above components enables the silicone rubber material to have excellent transparency and light stability.

[0014] In some embodiments, the benzotriazole silane coupling agent is prepared by dispersing a hydroxybenzotriazole compound and an isocyanate silane coupling agent in toluene, and reacting at 25-35°C for 1-3h to obtain the benzotriazole silane coupling agent.

[0015] In some embodiments described above, the benzotriazole structure is fixed in a stable covalent form in the silane molecule by urethane bond connection between the hydroxybenzotriazole compound and the isocyanate silane coupling agent under mild conditions, avoiding group detachment or structure destruction caused by light and thermal oxygen conditions, thereby ensuring the effective fixation of the anti-aging structure on the surface of the white carbon black. Compared with directly mixing benzotriazole into silicone rubber, the silanized structure constructed by the preparation method can form a more compact and uniform interface layer after hydrolysis and condensation, improve the coverage of the white carbon black surface and reduce the polar residual area, which is conducive to improving the dispersion of the filler in the silicone rubber and the consistency of the interface refractive index, thereby further improving the transparency and light stability of the material.

[0016] In some embodiments, the hydroxybenzotriazole compound is obtained by Williamson etherification reaction of 2-(2-hydroxy-5-methylphenyl) benzotriazole and bromine propyl alcohol.

[0017] In some embodiments described above, the 2-(2-hydroxy-5-methylphenyl) benzotriazole structure introduces an additional ortho-phenyl and methyl substitution, making the benzotriazole group present a larger conjugated skeleton and steric hindrance. This structure, on the one hand, improves the absorption capacity of ultraviolet light and high-energy blue light, and can form a more stable light stable layer at the filler interface; on the other hand, due to the restraint of the additional aromatic ring on the lone pair of electrons of the triazole ring and its significant steric hindrance, it further reduces the catalytic interference of Karstedt platinum catalyst.

[0018] In addition, the inventors found that compared with the direct reaction of 2-(2-hydroxy-5-methylphenyl) benzotriazole without etherification modification with isocyanate silane, the hydroxybenzotriazole obtained by Williamson etherification is more conducive to improving the light stability and long-term transparency of the transparent silicone rubber material of the present application. The possible reason is that by etherification reaction of 2-(2-hydroxy-5-methylphenyl) benzotriazole with bromine propyl alcohol, a flexible alkyl chain containing hydroxyl group is introduced into the molecule, forming a flexible bridge chain with moderate length between the benzotriazole group and the silane skeleton. This structure can not only provide a reactive site for isocyanate, but also improve the spreading property of benzotriazole on the surface of white carbon black, reduce the interface accumulation and uneven orientation caused by the high rigidity of benzotriazole body, improve the continuity of the interface layer, and strengthen the optical stability, thereby further optimizing the long-term optical performance.

[0019] Therefore, compared with unetherified benzotriazole, the hydroxybenzotriazole obtained by Williamson etherification is more suitable for the transparent silicone rubber system of the present application in terms of interface coverage, reaction controllability and light stability.

[0020] In some embodiments, the molar ratio of the hydroxybenzotriazole compound and the isocyanate silane coupling agent is 1:1 to 1.02, and the solid content of the reaction system is 40wt% to 50wt%.

[0021] In some of the above embodiments, the hydroxybenzotriazole compound and the isocyanate silane coupling agent are controlled to react at a substantially equimolar ratio, which can ensure the generation of urethane bonds to be more complete, avoiding side reactions or crosslinking tendency caused by excess isocyanate; when the isocyanate is slightly excessive, it can also compensate for the incomplete reaction of the hydroxybenzotriazole molecule due to the large steric hindrance, so that the structure of the benzotriazole silane coupling agent formed finally is more stable and has less monomer residue. In addition, the solid content of the reaction system is controlled in the range of 40wt% to 50wt%, which can not only ensure the sufficient dissolution and dispersion of hydroxybenzotriazole, but also enable the silane coupling agent to maintain appropriate fluidity, improve the reaction contact efficiency, reduce the incomplete reaction caused by low concentration or the partial condensation of silane caused by high concentration, so that the obtained benzotriazole silane has good structural uniformity and use stability, thereby helping to improve the transparency, interface refractive index consistency and light stability of the final silicone rubber material.

[0022] In some embodiments, the silicone oil grafted silane coupling agent is prepared by dispersing hydrogen-terminated polydimethylsiloxane, vinyl silane coupling agent and Karstedt catalyst in toluene, and reacting at 70-90°C for 3-5h to obtain the silicone oil grafted silane coupling agent.

[0023] In some embodiments described above, by allowing hydrogen-terminated polydimethylsiloxane to react with vinyl silane coupling agent in the presence of Karstedt catalyst, a hydrolyzable condensation silane structure can be introduced at the end of the PDMS segment, so that the resulting coupling agent has both siloxane flexible segment and silane interfacial reaction group. The silicone oil grafted silane coupling agent prepared by the above addition reaction not only retains the flexible properties of the polydimethylsiloxane segment, but also has high compatibility with the silicone rubber matrix. It can also participate in hydrolytic condensation on the surface of white carbon black through the silane group to achieve firm grafting, effectively improve the flexibility and chemical bonding degree of the filler interface layer, and improve the spreading ability and dispersion stability of the filler in the silicone rubber. The coupling agent obtained in this embodiment can form a more stable flexible interface layer on the surface of the filler, making the refractive index of the interface closer to the silicone rubber matrix, thereby further improving the transparency and long-term optical stability of the material.

[0024] In some embodiments, the number average molecular weight of the hydrogen-terminated polydimethylsiloxane is 1000-2000; the molar ratio of the hydrogen-terminated polydimethylsiloxane and the vinyl silane coupling agent is 1:1-1.02, and the concentration of the Karstedt catalyst in the reaction system is 0.001wt%-0.01wt%; the solid content of the reaction system is 20wt%-40wt%.

[0025] In some embodiments described above, the molecular weight of the hydrogen-terminated polydimethylsiloxane is controlled in the range of 1000-2000, which can make the PDMS segment have appropriate molecular size while maintaining flexibility, so that it can form an effective flexible cover layer on the surface of the white carbon black, without causing insufficient interface stability due to too short chain segment or affecting grafting efficiency due to limited condensation reaction caused by too long chain segment. Controlling the molar ratio of hydrogen-terminated PDMS and vinyl silane coupling agent to 1:1-1:1.02 can ensure that the Si-H / C=C addition reaction is more complete, avoiding the residual of unadded Si-H due to insufficient vinyl group. Controlling the concentration of Karstedt catalyst in the range of 0.001wt%-0.01wt% can ensure that the addition reaction proceeds efficiently, making the structure of the silicone oil grafted silane coupling agent more uniform and stable. Controlling the solid content of the reaction system in the range of 20wt%-40wt% can ensure the flowability and mixing efficiency of the reactants, avoid silane condensation side reactions caused by too high solid content, and prevent the problem of decreased reaction efficiency or uneven distribution of molecular segments caused by too low solid content.

[0026] Therefore, by controlling the molecular weight of the hydrogen-terminated polydimethylsiloxane, the molar ratio of the addition reaction, and the amount of Karstedt catalyst used, and limiting the reaction solid content within an appropriate range, the resulting silicone oil grafted silane coupling agent has a more uniform molecular structure and higher grafting efficiency, making the flexible interface layer formed on the surface of the white carbon black more complete and continuous, thereby further improving the optical properties and long-term stability of the silicone rubber material.

[0027] In some embodiments, the modified white carbon black is prepared by the following steps:

[0028] S1: dispersing the white carbon black and the benzotriazole silane coupling agent in an aqueous ethanol solution, allowing the benzotriazole silane coupling agent to hydrolyze and condense onto the surface of the white carbon black, to obtain benzotriazole grafted white carbon black;

[0029] S2: dispersing the benzotriazole grafted white carbon black and the silicone oil grafted silane coupling agent in an aqueous ethanol solution, allowing the silicone oil grafted silane coupling agent to hydrolyze and condense onto the surface of the white carbon black, to obtain the modified white carbon black.

[0030] In some of the above embodiments, by preferentially hydrolyzing and condensing the benzotriazole silane coupling agent onto the surface of the white carbon black in the first step, an initial interface layer mainly composed of benzotriazole groups can be formed on the surface layer of the filler. Since the benzotriazole structure has a strong ability to absorb high-energy photons and can inhibit the generation of photo-excited free radicals on the surface of the white carbon black through energy dissipation, this step can effectively reduce the photosensitivity of the white carbon black under ultraviolet and blue light conditions. In addition, the benzotriazole silane coupling agent can undergo a highly efficient condensation reaction with the hydroxyl groups on the surface of the white carbon black, allowing the benzotriazole structure to be firmly attached to the surface of the filler in the form of a covalent bond, thereby improving the stability of the interface layer; at the same time, this interface layer can significantly reduce the polarity of the surface of the white carbon black, making it easier for the subsequent silicone oil grafted silane to spread and graft on the surface, reducing the phenomenon of local condensation deficiency or uneven coverage caused by differences in surface polarity.

[0031] Therefore, by using the benzotriazole silane coupling agent as the first step for surface modification of the white carbon black, a stable and uniform light-stable layer can be obtained on the surface of the filler, effectively inhibiting the structural degradation of the filler interface under light conditions and reducing the tendency of the white carbon black to agglomerate; in combination with the flexible matching layer constructed by the silicone oil grafted silane coupling agent in the second step, the refractive index consistency of the filler interface can be further improved, significantly improving the dispersibility and transparency of the white carbon black in the silicone rubber, thereby enhancing the light stability and long-term light transmission performance of the final silicone rubber material.

[0032] In some embodiments, the modified white carbon black is prepared by the following steps:

[0033] S1: dispersing 100 parts of white carbon black with an average particle size of 10-20 nm and 6-10 parts of benzotriazole silane coupling agent in 400-600 parts of an ethanol aqueous solution, and reacting at 50-70℃ for 2-4 h to obtain benzotriazole grafted white carbon black;

[0034] S2: dispersing 100 parts of benzotriazole grafted white carbon black and 4-6 parts of silicone oil grafted silane coupling agent in 400-600 parts of an ethanol aqueous solution, and reacting at 50-70℃ for 3-5 h to obtain modified white carbon black.

[0035] In some of the above embodiments, the amount of benzotriazole silane coupling agent used in the first step is controlled to be 6-10 parts, which can make the benzotriazole silane preferentially hydrolyze and condense with part of the hydroxyl groups on the surface of the white carbon black to form an initial interface layer mainly composed of benzotriazole groups, while still retaining a certain number of unreacted silanol sites, facilitating the condensation of the silicone oil grafted silane in the second step. This "partial coverage + uniform distribution" structure can effectively reduce the polarity of the surface of the white carbon black, improve the dispersion stability of the filler, and provide reasonable chemical sites for the construction of the flexible siloxane interface layer in the second step.

[0036] In the second step, the silicone oil grafted silane coupling agent continues to hydrolyze and condense on the residual silanol sites, forming a flexible siloxane matching layer outside the benzotriazole initial layer, making the interface refractive index closer to the silicone rubber matrix. This layer not only provides flexibility, but also improves the interface compatibility, making the filler more easily dispersed in the mixing process.

[0037] Therefore, by the above-mentioned preferred two-step modification method, a composite interface structure composed of a "benzotriazole light stabilization layer + silicone oil flexible matching layer" can be constructed on the surface of the white carbon black, effectively balancing light stability, refractive index consistency and dispersion, thereby further improving the transparency and long-term optical stability of the final silicone rubber material.

[0038] In some embodiments, the methyl vinyl phenyl rubber has a viscosity of 10-50 Pa·s at 25℃, a vinyl content of 0.1mol%-0.3mol%, and a phenyl content of 4mol%-8mol%. Based on the above embodiments, the moderate viscosity and vinyl content can ensure that the silicone rubber matrix has good flow dispersion during mixing, making the modified white carbon black more easily spread uniformly in the system; controlling the phenyl content within a certain range can improve the degree of matching of the interface refractive index between the matrix and the filler, so that the material has higher transparency while maintaining more stable optical properties.

[0039] In some embodiments, the vinyl MQ silicone resin has a viscosity of 5000-15000 mPa·s at 25℃, a value of M / Q of 0.7-0.9, and a vinyl content of 0.5-2 wt%. Based on the above embodiments, the suitable viscosity and M / Q ratio can make the MQ structure form a uniform and dense three-dimensional reinforcing network, thereby improving the transparency and mechanical strength of the molded silicone rubber; and the vinyl content kept in the appropriate range can make the addition reaction with the matrix more uniform.

[0040] In some embodiments, the polymethylhydrogenosiloxane has a viscosity of 0.01-0.1 Pa·s at 25℃, and a hydrogen content of 0.1 wt%-1 wt%. Based on the above embodiments, the low viscosity PMHS can be quickly dispersed and participate in addition curing in the mixing process, so that the crosslinking network is more uniform; and the hydrogen content controlled in the appropriate range can avoid excessive or insufficient local crosslinking, so that the refractive index of the cured film is stable and consistent, which helps to improve the transparency and light stability of the entire material.

[0041] In some embodiments, the vinyl-hydroxyl silicone oil has a viscosity of 20-100 mPa·s at 25℃, a vinyl content of 6 mol%-7 mol%, and a hydroxyl content of 5.5 mol%-6.5 mol%. Based on the above embodiments, the vinyl-hydroxyl silicone oil can not only supplement the crosslinking active sites, but also form an auxiliary effect through the hydroxyl and filler interface, so that the density of the flexible segment at the interface is increased, and the passivation is supplemented; and the viscosity and vinyl content controlled in the appropriate range can improve the crosslinking uniformity and reduce the interface light scattering points, thereby improving the transparency.

[0042] In some embodiments, the vinyl-hydroxyl silicone oil has a viscosity of 20-100 mPa·s at 25℃, and the platinum catalyst includes Karstedt catalyst. Based on the above embodiments, the Karstedt catalyst has high and mild addition catalytic activity, which can make the silicone rubber system achieve sufficient crosslinking at a lower catalyst dosage, thereby improving the transparency and light stability of the material.

[0043] In a second aspect, the present application provides a method for preparing a high-transparency silicone rubber material, comprising:

[0044] providing raw materials of the silicone rubber according to any one of the embodiments of the first aspect;

[0045] mixing and curing the raw materials to obtain a high-transparency silicone rubber material.

[0046] According to the present application, by mixing, uniformly dispersing and addition curing the base rubber, modified white carbon black, silicone resin, silicon-hydrogen crosslinking agent and platinum catalyst in sequence according to the formula system of the first aspect, a uniform and continuous siloxane three-dimensional network structure can be constructed in the curing process, and a composite interface system of "benzotriazole light stabilization layer-silicone oil flexible matching layer" can be formed at the filler interface. The above method not only can ensure the uniform dispersion of the filler during the mixing process, keep the interface refractive index stable and consistent, so that the cured silicone rubber material has higher transparency, but also can maintain the chemical stability of the interface after curing, improve the anti-yellowing ability and long-term optical stability of the material during light irradiation. Therefore, the silicone rubber material prepared by the method of the present application can obtain better comprehensive performance in transparency and light stability.

[0047] Compared with the prior art, the present application has at least the following beneficial effects:

[0048] By simultaneously using benzotriazole silane coupling agent and silicone oil grafted silane coupling agent for double interface modification of the white carbon black, a composite interface layer with light stability and refractive index matching function can be constructed on the surface of the filler, so that the white carbon black has higher dispersion uniformity and interface stability in the silicone rubber, thereby significantly reducing light scattering and improving the transparency of the material. At the same time, the benzotriazole structure can inhibit the color change induced by light irradiation, and cooperates with the silicone oil segment to effectively improve the long-term optical stability of the silicone rubber under ultraviolet light and high-energy blue light. In combination with the optimized silicone rubber matrix and crosslinking system, the obtained silicone rubber material has higher transparency, better interface stability and better light stability, thereby improving its application performance and service life in optoelectronic display, LED packaging and high-end transparent products. DETAILED DESCRIPTION

[0049] Each embodiment or implementation in the present specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments.

[0050] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the implementation or example are included in at least one implementation or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more implementations or examples in a suitable manner.

[0051] Moreover, the terms "first", "second", etc. are used herein for descriptive purposes only and should not be construed as indicating or implying relative importance or an ordered sequence. Thus, features referring to "first", "second" etc. can include at least one of the features, explicitly or implicitly.

[0052] In the description of the present specification, "parts" means "mass parts" unless otherwise specified.

[0053] Hereinafter, the examples of the present application will be described. The examples described below are illustrative and are intended to explain the present application, and are not to be construed as limiting the present application. In the examples, the specific techniques or conditions not mentioned are performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be obtained on the market.

[0054] 2-(2-hydroxy-5-methylphenyl)benzotriazole, CAS No. 2440-22-4;

[0055] Bromopropanol, i.e. 3-bromo-1-propanol, CAS No. 627-18-9;

[0056] Isocyanato propyl triethoxysilane, CAS No. 24801-88-5;

[0057] Vinyltrimethoxysilane, CAS No. 2768-02-7;

[0058] White carbon black, model No. JiPeng CY-SP15, average particle size 15 nm;

[0059] Methyl vinyl phenyl rubber, viscosity at 25°C 40 Pa s, vinyl content 0.2 mol%, phenyl content 6%;

[0060] Vinyl MQ silicone resin, i.e. methyl vinyl MQ silicone resin, viscosity at 25°C 9000 mPa s, M / Q value 0.8, vinyl content 1.5 wt%;

[0061] Vinyl hydroxy silicone oil, viscosity at 25°C 35 mPa s, vinyl content 6.5 mol%, hydroxyl content 6 mol%;

[0062] Polymethyl hydrogen siloxane, viscosity at 25°C 0.05 Pa s, hydrogen content 0.5 wt%.

[0063] Preparation Example 1-1

[0064] Preparation of benzotriazole silane coupling agent:

[0065] In a three-necked flask, 2-(2-hydroxy-5-methylphenyl)benzotriazole and 3-bromopropanol were added, the molar ratio was controlled to be 1:1.05, anhydrous potassium carbonate was added as an acid capturing agent (1.2 times of the molar amount of 2-(2-hydroxy-5-methylphenyl)benzotriazole), and anhydrous DMF was added as a solvent, so that the solid content of the system was 40wt%. The reaction temperature was controlled to be 70°C under a nitrogen atmosphere, and the reaction was carried out for 6h. After the reaction was completed, the product was poured into ice water, and concentrated under reduced pressure to obtain an etherification product, which was dried to obtain a hydroxybenzotriazole intermediate;

[0066] The above hydroxybenzotriazole intermediate and isocyanate propyl triethoxysilane were added to toluene, the molar ratio of the two was controlled to be 1:1.01, and the solid content of the system was adjusted to be 45wt%. The hydroxyl group and the isocyanate group were subjected to a carbamate reaction under stirring at 30°C for 2h under the protection of nitrogen. After the reaction was completed, the system was cooled to room temperature, and toluene was removed by rotary evaporation. The product was recorded as benzotriazole silane coupling agent A.

[0067] Preparation Example 1-2

[0068] Preparation of a benzotriazole silane coupling agent:

[0069] The above hydroxybenzotriazole intermediate and isocyanate propyl triethoxysilane were added to toluene, the molar ratio of the two was controlled to be 1:1.01, and the solid content of the system was adjusted to be 45wt%. The hydroxyl group and the isocyanate group were subjected to a carbamate reaction under stirring at 30°C for 2h under the protection of nitrogen. After the reaction was completed, the system was cooled to room temperature, and toluene was removed by rotary evaporation. The product was recorded as benzotriazole silane coupling agent A.

[0070] Preparation Example 2-1

[0071] Preparation of a benzotriazole silane coupling agent:

[0072] Hydrogen-terminated polydimethylsiloxane with a number average molecular weight of about 1500 and vinyl triethoxysilane were added to a three-necked flask, toluene was added as a solvent, the molar ratio of the hydrogen-terminated polydimethylsiloxane and the vinyl triethoxysilane was controlled to be 1:1.01, and the solid content of the system was adjusted to be 30wt%. Karstedt catalyst was added to the system, so that the mass fraction of the catalyst in the reaction system was 0.005wt%. The reaction was carried out under stirring at 80°C for 4h under a nitrogen atmosphere. After the reaction was completed, the system was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was recorded as silicone oil grafted silane coupling agent A.

[0073] Preparation Example 2-2

[0074] Preparation of a benzotriazole silane coupling agent:

[0075] Hydrogen-terminated polydimethylsiloxane with number average molecular weight of about 500 and vinyltriethoxysilane were added into a three-necked flask, toluene was added as solvent, the molar ratio of hydrogen-terminated polydimethylsiloxane to vinyltriethoxysilane was controlled to be 1:1.01, and the solid content of the system was adjusted to be 30wt%. Karstedt catalyst was added into the system, so that the mass fraction of Karstedt catalyst in the reaction system was 0.005wt%. The reaction was stirred at 80°C for 4h under a nitrogen atmosphere, and after the reaction was completed, the system was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was denoted as silicone oil grafted silane coupling agent B.

[0076] Preparation Example 2-3

[0077] Preparation of silicone oil grafted silane coupling agent:

[0078] Hydrogen-terminated polydimethylsiloxane with number average molecular weight of about 2500 and vinyltriethoxysilane were added into a three-necked flask, toluene was added as solvent, the molar ratio of hydrogen-terminated polydimethylsiloxane to vinyltriethoxysilane was controlled to be 1:1.01, and the solid content of the system was adjusted to be 30wt%. Karstedt catalyst was added into the system, so that the mass fraction of Karstedt catalyst in the reaction system was 0.005wt%. The reaction was stirred at 80°C for 4h under a nitrogen atmosphere, and after the reaction was completed, the system was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was denoted as silicone oil grafted silane coupling agent C.

[0079] Preparation Example 3-1

[0080] Preparation of modified white carbon black:

[0081] Into a three-necked flask, 100 parts of white carbon black with an average particle size of 15nm and 8 parts of benzotriazole silane coupling agent A were added, and 500 parts of a mixed solution of ethanol / water (volume fraction 95:5) was added. The system was uniformly dispersed by starting mechanical stirring. The reaction was carried out at 60°C for 3h, so that the benzotriazole silane coupling agent was hydrolyzed and condensed and grafted onto the surface of the white carbon black. After the reaction was completed, the system was cooled to room temperature, and unreacted substances and low molecular weight impurities were removed by suction filtration and water washing. The system was dried at 80°C to obtain benzotriazole grafted white carbon black.

[0082] Into a new reaction kettle, 100 parts of the above obtained benzotriazole grafted white carbon black and 5 parts of silicone oil grafted silane coupling agent A were added, and 500 parts of a mixed solution of ethanol / water (volume fraction 95:5) was added. After the system was uniformly dispersed by stirring, the reaction was carried out at 60°C for 4h, so that the silicone oil grafted silane coupling agent was further hydrolyzed and condensed and formed a flexible siloxane interface layer on the surface of the white carbon black. After the reaction was completed, the system was cooled to room temperature, and the solid was suction filtered and washed with ethanol and deionized water in sequence. The system was dried at 80°C to obtain modified white carbon black A.

[0083] Preparation Example 3-2

[0084] Preparation of modified white carbon black:

[0085] In a three-necked flask, 100 parts of white carbon black with an average particle size of 15 nm and 8 parts of benzotriazole silane coupling agent B were added, and 500 parts of a mixed solution of ethanol / water (volume fraction of 95:5) was added. The system was uniformly dispersed by opening the mechanical stirring. The benzotriazole silane coupling agent was allowed to undergo hydrolysis and condensation and grafting to the surface of the white carbon black at 60°C for 3 h. After the reaction was completed, it was cooled to room temperature, and unreacted substances and low molecular weight impurities were removed by suction filtration and water washing, and dried at 80°C to obtain benzotriazole grafted white carbon black.

[0086] The above obtained 100 parts of benzotriazole grafted white carbon black and 5 parts of silicone oil grafted silane coupling agent A were added to a new reaction kettle, 500 parts of a mixed solution of ethanol / water (volume fraction of 95:5) was added, and after uniform dispersion by stirring, the silicone oil grafted silane coupling agent was allowed to continue to undergo hydrolysis and condensation on the surface of the white carbon black and form a flexible siloxane interface layer at 60°C for 4 h. After the reaction was completed, it was cooled to room temperature, the solid was suction filtered, washed with ethanol and deionized water in turn, and dried at 80°C to obtain modified white carbon black B.

[0087] Preparation Example 3-3

[0088] Preparation of modified white carbon black:

[0089] In a three-necked flask, 100 parts of white carbon black with an average particle size of 15 nm and 8 parts of benzotriazole silane coupling agent A were added, and 500 parts of a mixed solution of ethanol / water (volume fraction of 95:5) was added. The system was uniformly dispersed by opening the mechanical stirring. The benzotriazole silane coupling agent was allowed to undergo hydrolysis and condensation and grafting to the surface of the white carbon black at 60°C for 3 h. After the reaction was completed, it was cooled to room temperature, and unreacted substances and low molecular weight impurities were removed by suction filtration and water washing, and dried at 80°C to obtain benzotriazole grafted white carbon black.

[0090] The above obtained 100 parts of benzotriazole grafted white carbon black and 5 parts of silicone oil grafted silane coupling agent B were added to a new reaction kettle, 500 parts of a mixed solution of ethanol / water (volume fraction of 95:5) was added, and after uniform dispersion by stirring, the silicone oil grafted silane coupling agent was allowed to continue to undergo hydrolysis and condensation on the surface of the white carbon black and form a flexible siloxane interface layer at 60°C for 4 h. After the reaction was completed, it was cooled to room temperature, the solid was suction filtered, washed with ethanol and deionized water in turn, and dried at 80°C to obtain modified white carbon black C.

[0091] Preparation Example 3-4

[0092] Preparation of modified white carbon black:

[0093] Into a three-necked flask, 100 parts of white carbon black with an average particle size of 15 nm and 8 parts of benzotriazole silane coupling agent A were added, and 500 parts of a mixed solution of ethanol / water (volume fraction of 95:5) was added. The system was uniformly dispersed by opening the mechanical stirring. The benzotriazole silane coupling agent was allowed to hydrolyze and condense and graft onto the surface of the white carbon black at 60°C for 3h. After the reaction was completed, it was cooled to room temperature, and unreacted substances and low molecular weight impurities were removed by suction filtration and water washing. Drying was performed at 80°C to obtain benzotriazole grafted white carbon black.

[0094] Into a new reaction kettle, 100 parts of the above obtained benzotriazole grafted white carbon black and 5 parts of silicone oil grafted silane coupling agent C were added, and 500 parts of a mixed solution of ethanol / water (volume fraction of 95:5) was added. After uniform dispersion by stirring, the silicone oil grafted silane coupling agent was allowed to continue to hydrolyze and condense on the surface of the white carbon black and form a flexible siloxane interface layer at 60°C for 4h. After the reaction was completed, it was cooled to room temperature, and the solid was suction filtered, washed with ethanol and deionized water in sequence, and dried at 80°C to obtain modified white carbon black D.

[0095] Preparation Example 3-5

[0096] Preparation of modified white carbon black:

[0097] Into a three-necked flask, 100 parts of white carbon black with an average particle size of 15 nm, 8 parts of benzotriazole silane coupling agent A and 5 parts of silicone oil grafted silane coupling agent A were added, and 1000 parts of a mixed solution of ethanol / water (volume fraction of 95:5) was added. The system was uniformly dispersed by opening the mechanical stirring. The benzotriazole silane coupling agent and the silicone oil grafted silane coupling agent were allowed to hydrolyze and condense and graft onto the surface of the white carbon black at 60°C for 5h. After the reaction was completed, it was cooled to room temperature, and unreacted substances and low molecular weight impurities were removed by suction filtration and water washing. Drying was performed at 80°C to obtain modified white carbon black E.

[0098] Comparative Preparation Example 3-1

[0099] Preparation of modified white carbon black:

[0100] Into a three-necked flask, 100 parts of white carbon black with an average particle size of 15 nm, 8 parts of benzotriazole silane coupling agent A and 5 parts of silicone oil grafted silane coupling agent A were added, and 1000 parts of a mixed solution of ethanol / water (volume fraction of 95:5) was added. The system was uniformly dispersed by opening the mechanical stirring. The benzotriazole silane coupling agent and the silicone oil grafted silane coupling agent were allowed to hydrolyze and condense and graft onto the surface of the white carbon black at 60°C for 5h. After the reaction was completed, it was cooled to room temperature, and unreacted substances and low molecular weight impurities were removed by suction filtration and water washing. Drying was performed at 80°C to obtain modified white carbon black E.

[0101] Comparative Preparation Example 3-2

[0102] Preparation of modified white carbon black:

[0103] In a three-neck flask, 100 parts of white carbon black with an average particle size of 15 nm, 13 parts of silicone oil grafted silane coupling agent A, 1000 parts of a mixed solution of ethanol / water (volume fraction of 95:5) were added, and mechanical stirring was started to uniformly disperse the system. Hydrolysis and condensation of the silicone oil grafted silane coupling agent and grafting to the surface of the white carbon black were carried out at 60°C for 6h. After the reaction was completed, the system was cooled to room temperature, and unreacted substances and low molecular weight impurities were removed by suction filtration and water washing. Drying was carried out at 80°C to obtain modified white carbon black G.

[0104] Example 1

[0105] Preparation of high-transparency silicone rubber material:

[0106] In an internal mixer, 100 parts of methylvinylphenyl silicone rubber were added, and stirring was started. Then, 20 parts of modified white carbon black A and 4 parts of vinyl MQ silicone resin were added in sequence to completely wet and uniformly disperse the fillers, and the mixing temperature was maintained at 120°C for 15 min.

[0107] Then, 5 parts of polymethylhydrogen silicone and 1.2 parts of vinyl hydroxyl silicone oil were added to the system. Mixing was continued for 10 min to fully compatibilize them with the matrix.

[0108] Finally, 0.002 parts of Karstedt platinum catalyst were added, and mixing was continued for 3 min to uniformly disperse the catalyst. Mixing was stopped, and the rubber compound was placed in a vacuum deaerator for deaeration at 60°C for 10 min to obtain a transparent and uniform silicone rubber compound.

[0109] The deaerated rubber compound was placed in a mold at 150°C, and hot vulcanization was carried out at 10 MPa for 10 min, followed by two-stage vulcanization at 180°C for 2h to obtain a high-transparency silicone rubber material with a transparent appearance, uniformity, and no bubbles.

[0110] Example 2

[0111] Preparation of high-transparency silicone rubber material:

[0112] The preparation was basically the same as in Example 1, except that modified white carbon black B was used instead of modified white carbon black A.

[0113] Example 3

[0114] Preparation of high-transparency silicone rubber material:

[0115] The preparation was basically the same as in Example 1, except that modified white carbon black C was used instead of modified white carbon black A.

[0116] Example 4

[0117] Preparation of high-transparency silicone rubber material:

[0118] The same as Example 1, except that modified white carbon black D is used instead of modified white carbon black A.

[0119] Example 5

[0120] Preparation of high transparent silicone rubber material:

[0121] The same as Example 1, except that modified white carbon black E is used instead of modified white carbon black A.

[0122] Comparative Example 1

[0123] Preparation of high transparent silicone rubber material:

[0124] The same as Example 1, except that modified white carbon black F is used instead of modified white carbon black A.

[0125] Comparative Example 2

[0126] Preparation of high transparent silicone rubber material:

[0127] The same as Example 1, except that modified white carbon black G is used instead of modified white carbon black A.

[0128] Comparative Example 3

[0129] Preparation of high transparent silicone rubber material:

[0130] Into a mixer, 100 parts of methyl vinyl phenyl silicone rubber was added and the stirring was started. Then 20 parts of white carbon black, 1.6 parts of benzotriazole silane coupling agent A, 1 part of silicone oil grafted silane coupling agent A and 4 parts of vinyl MQ silicone resin were added in sequence to make the fillers fully wetted and uniformly dispersed, and the mixing temperature was kept at 120°C and the mixing time was 15 min.

[0131] Then 5 parts of polymethyl hydrogen silicone and 1.2 parts of vinyl hydroxyl silicone oil were added into the system. The mixing was continued for 10 min to make them fully compatible with the matrix.

[0132] Finally, 0.002 parts of Karstedt platinum catalyst was added and the mixing was continued for 3 min to make the catalyst uniformly dispersed. The mixing was stopped and the rubber compound was placed in a vacuum deaerator to be deaerated at 60°C for 10 min to obtain a transparent and uniform silicone rubber compound.

[0133] The deaerated rubber compound was placed in a mold at 150°C and hot pressed at 10 MPa for 10 min, and then two-stage vulcanized at 180°C for 2 h to obtain a high transparent silicone rubber material with transparent appearance, uniformity and no bubbles.

[0134] Test Part

[0135] The high transparent silicone rubber materials obtained in the above examples and comparative examples were cut into samples with a thickness of 2±0.1 mm for the following tests:

[0136] Transmittance test: According to GB / T 2410-2008, the sample was placed in the light path of the transmittance tester, and the transmittance T0(%) was measured under visible light with a wavelength of 550 nm. The results are shown in Table 1.

[0137] Transmittance retention rate test after light aging: the sample was placed in a light aging oven, a blue light LED light source with a main peak wavelength of about 450 nm was used, the sample surface irradiance was controlled at 20 W / m 2 , the distance between the sample and the light source was kept constant, and the sample was continuously irradiated at 25°C for 100 h. After irradiation, the transmittance T1(%) after light aging was tested according to the above transmittance test method, and the transmittance retention rate δ(%) after light aging was calculated as T1 / T0x100%. The results are shown in Table 1.

[0138] Table 1

[0139]

[0140] According to Table 1, the initial transmittance T0of each example is significantly higher than that of Comparative Examples 1-3, and each example has a high transmittance retention rate δ after light aging, indicating that the transparent silicone rubber material provided by the present application has significant advantages in both transparency and light aging stability. The possible reason is that in Comparative Example 1, the surface of the white carbon black is only grafted with a benzotriazole silane coupling agent, and there is a lack of flexible siloxane chain segments in the interface layer to adjust the refractive index, causing a refractive index mutation at the local interface and forming light scattering points, thereby significantly reducing the initial transmittance. In Comparative Example 2, the surface of the white carbon black is only grafted with a silicone oil grafted silane coupling agent, which is beneficial to improving the initial transparency, but the system lacks effective anti-aging structures, and the free radicals generated by the silicone rubber main chain under blue light irradiation are difficult to be captured in time, resulting in a significantly lower transmittance retention rate. In Comparative Example 3, the benzotriazole silane coupling agent and the silicone oil grafted silane coupling agent are added in a physical blending manner, which fails to form a uniform and stable interface layer on the surface of the white carbon black, resulting in uneven distribution of the two types of functional groups in the mixing gum. In addition, a small amount of free benzotriazole silane coupling agent in the system may have a certain toxic effect on Karstedt catalyst, resulting in a significant decrease in transparency and light stability compared to the examples.

[0141] According to Example 1 and Example 2, the hydroxybenzotriazole structure obtained by Williamson etherification can obtain better performance in both transparency and light retention, indicating that the molecular configuration of the benzotriazole structure has a significant impact on the uniformity and light stability of the interface layer. After etherification modification, the benzotriazole group can be more fully spread on the surface of the white carbon black through the flexible alkyl chain segment, forming a more uniform and complete anti-aging layer, while avoiding the local accumulation and interface discontinuity that may occur when the unmodified benzotriazole directly contacts the interface. Therefore, the benzotriazole silane coupling agent modified by etherification can better play a comprehensive role in stabilizing transparency and inhibiting photodegradation in the transparent silicone rubber system.

[0142] According to Example 1, Example 3 and Example 4, the molecular weight of the polydimethylsiloxane segment in the silicone oil grafted silane coupling agent has an impact on both transparency and light stability. Shorter segments are not easy to form a continuous flexible refractive index transition layer on the surface of the white carbon black, resulting in a lower initial light transmittance; too long segments may cause local stacking or curling, which will reduce the uniformity of the interface layer and also cause a slight increase in scattering. In contrast, the medium molecular weight silicone oil segment is more suitable for building a uniform flexible interface layer on the surface of the white carbon black, which can play a role in both refractive index matching and free radical buffering, so Example 1 shows better transparency and stability.

[0143] According to Example 1 and Example 5, the material prepared by the stepwise grafting method is better than the material prepared by the one-pot synchronous grafting method, indicating that the reaction order of the two types of coupling agents has a significant impact on the structure of the interface layer. Stepwise grafting can make benzotriazole form a dense and uniform light-stable layer on the surface of the white carbon black first, and then build a flexible refractive index adjusting layer by the silicone oil grafted silane coupling agent, thereby forming a more ordered double-layer interface structure; while synchronous grafting, the two types of coupling agents will compete for the same hydrolysis and condensation sites, which is easy to cause uneven distribution or incomplete local film, so the transparency and light stability are not as good as Example 1.

[0144] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A highly transparent silicone rubber material, characterized by, The raw materials include the following quality parts: 100 parts of methyl vinyl phenyl silicone rubber, 10-30 parts of modified white carbon black, 3-5 parts of vinyl MQ silicone resin, 4-6 parts of polymethyl hydrogen siloxane, 1-1.5 parts of vinyl hydroxyl silicone oil, and 0.001-0.003 parts of platinum catalyst; The modified white carbon black is obtained by grafting the white carbon black with a benzotriazole silane coupling agent and a silicone oil grafted silane coupling agent; the benzotriazole silane coupling agent is obtained by urethane reaction of a hydroxybenzotriazole compound and an isocyanate silane coupling agent; and the silicone oil grafted silane coupling agent is obtained by addition reaction of hydrogen-terminated polydimethylsiloxane and a vinyl silane coupling agent. The hydroxybenzotriazole compound is obtained by Williamson etherification reaction of 2-(2-hydroxy-5-methylphenyl) benzotriazole and bromine propyl alcohol.

2. The silicone rubber material according to claim 1, characterized in that, The benzotriazole silane coupling agent is prepared by the following method: The hydroxybenzotriazole compound and the isocyanate silane coupling agent are dispersed in toluene, and reacted at 25-35℃ for 1-3h to obtain the benzotriazole silane coupling agent.

3. The silicone rubber material according to claim 1, characterized in that, The molar ratio of the hydroxybenzotriazole compound and the isocyanate silane coupling agent is 1:1-1.02, and the solid content of the reaction system is 40wt%-50wt%.

4. The silicone rubber material according to claim 1, characterized in that, The silicone oil grafted silane coupling agent is prepared by the following method: The hydrogen-terminated polydimethylsiloxane, the vinyl silane coupling agent and the Karstedt catalyst are dispersed in toluene, and reacted at 70-90℃ for 3-5h to obtain the silicone oil grafted silane coupling agent.

5. The silicone rubber material according to claim 4, characterized in that, The number average molecular weight of the hydrogen-terminated polydimethylsiloxane is 1000-2000; the molar ratio of the hydrogen-terminated polydimethylsiloxane and the vinyl silane coupling agent is 1:1-1.02, and the concentration of the Karstedt catalyst in the reaction system is 0.001wt%-0.01wt%; and the solid content of the reaction system is 20wt%-40wt%.

6. The silicone rubber material according to claim 1, characterized in that, The modified white carbon black is prepared by the following steps: S1: dispersing the white carbon black and the benzotriazole silane coupling agent in an aqueous ethanol solution, and grafting the benzotriazole silane coupling agent onto part of the surface of the white carbon black by hydrolysis and condensation to obtain benzotriazole grafted white carbon black; S2: dispersing the benzotriazole grafted white carbon black and the silicone oil grafted silane coupling agent in an aqueous ethanol solution, and grafting the silicone oil grafted silane coupling agent onto the surface of the white carbon black by hydrolysis and condensation to obtain the modified white carbon black.

7. The silicone rubber material according to claim 6, characterized in that, The modified white carbon black is prepared by the following steps: S1: dispersing 100 parts of white carbon black with an average particle size of 10-20nm and 6-10 parts of benzotriazole silane coupling agent in 400-600 parts of aqueous ethanol solution, and reacting at 50-70℃ for 2-4h to obtain benzotriazole grafted white carbon black; S2: dispersing 100 parts of benzotriazole grafted white carbon black and 4-6 parts of silicone oil grafted silane coupling agent in 400-600 parts of aqueous ethanol solution, and reacting at 50-70℃ for 3-5h to obtain the modified white carbon black.

8. The silicone rubber material according to any one of claims 1 to 7, characterized in that, The raw materials satisfy at least one of the following conditions: 1) the viscosity of the methylvinylphenyl silicone rubber at 25℃ is 10~50Pa·s, the vinyl content is 0.1mol%~0.3mol%, the phenyl content is 4mol%~8mol%; 2) the viscosity of the vinyl MQ silicone resin at 25℃ is 5000~15000mPa·s, the value of M / Q is 0.7~0.9, the vinyl content is 0.5~2wt%; 3) the viscosity of the polymethylhydrogen silicone at 25℃ is 0.01~0.1Pa·s, the hydrogen content is 0.1wt%~1wt%; 4) the viscosity of the vinyl hydroxyl silicone oil at 25℃ is 20~100mPa·s, the vinyl content is 6mol%~7mol%, the hydroxyl content is 5.5mol%~6.5mol%; 5) the platinum catalyst includes Karstedt catalyst.

9. A process for the preparation of highly transparent silicone rubber material, characterized in that, Comprise: providing raw materials of the silicone rubber according to any one of claims 1~8; mixing and curing the raw materials to obtain high transparent silicone rubber material.

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