A yellowing-resistant high-transmittance liquid silicone rubber and a preparation method thereof

Abstract

The application belongs to the technical field of liquid silicone rubber, and particularly relates to a liquid silicone rubber with high light transmittance and yellowing resistance and a preparation method thereof. The liquid silicone rubber comprises component A and component B. The component A comprises the following raw materials: base glue and a catalyst. The component B comprises the following raw materials: base glue, hydrogen-containing silicone oil and an inhibitor. The base glue comprises the following raw materials in mass fractions: 100 parts of vinyl silicone oil, 3-8 parts of white carbon black, 25-35 parts of silicone resin, 0.5-1 part of modifier A and 0.5-1 part of modifier B. The modifier A is hexamethyldisilazane, and the modifier B has the following structural formula. The liquid silicone rubber provided by the application has high light transmittance and excellent yellowing resistance under the conditions of ultraviolet light, high temperature and double 85, and is suitable for application as a car lens material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid silicone rubber, and particularly relates to a liquid silicone rubber with yellowing resistance and high light transmittance and a preparation method thereof. BACKGROUND

[0002] Liquid silicone rubber is a liquid elastomer material based on polysiloxane, which is in a fluid state at room temperature and can be cured into a high-performance elastomer through cross-linking. It is widely used in the fields of electronics and electrical appliances, food contact materials, medical devices, and automobiles. Among them, the light transmittance of optical-grade liquid silicone rubber is above 90%, and it is mainly used in products with high light transmittance requirements such as automobile headlights, high-transmittance mobile phone cases, sports goggles, earplugs, and glasses nose pads.

[0003] The performance requirements of liquid silicone rubber are different when it is applied in different products. When liquid silicone rubber is used in automobile headlights, it not only needs to have high light transmittance, but also needs to meet the performance requirements of automobile use scenarios. When it is used as a lens material, it needs to have long-term high-temperature resistance and ultraviolet resistance due to the heat and radiation of the LED light source.

[0004] The existing technology mainly focuses on the light transmittance and mechanical properties of liquid silicone rubber. For example, a Chinese patent with publication number CN119552510A discloses a high-refractive low-haze addition-type liquid silicone rubber and its preparation method. It is composed of vinyl silicone oil, catalyst, inhibitor, cross-linking agent, hydrophobic white carbon black, and white carbon black surface treatment agent. This technical solution realizes the addition-type liquid silicone rubber with high refractive index, high light transmittance, and low haze by adjusting the surface state of white carbon black and the refractive index of silicone oil. The addition-type liquid silicone rubber has good mechanical properties and good flowability, can adapt to continuous extrusion production, and has a Shore A hardness of 50-53, a light transmittance of above 94%, a haze of below 3%, a refractive index of 1.54 or above, and can be applied in the fields of optical devices and LED packaging.

[0005] A Chinese patent with publication number CN 118994921A discloses a high-transparency liquid silicone rubber composition and a preparation method thereof, which comprises: (A) linear polyorganosiloxane 30-50 parts by weight; (B) polyorganosiloxane with resin structure 50-70 parts by weight; (C) linear hydrogenated silicon functional polyorganosiloxane 0.5-6 parts by weight; (D) branched hydrogenated silicon functional polyorganosiloxane 0.8-8 parts by weight; (E) hydrogen silane reaction catalyst 0.3-0.7 parts by weight; (F) inhibitor 0.05-0.2 parts by weight. The high-transparency liquid silicone rubber composition provided by the technical solution can realize good overall interaction by using specific components in specific amounts, minimize T90, and maintain the strength and optical performance of the high-transparency silicone rubber composition without increasing the concentration of hydrogen silane catalyst and hydrogenated silicon functional groups under curing conditions of 120℃ / 5 minutes.

[0006] However, the above technical solutions do not pay attention to the yellowing resistance under ultraviolet, high temperature and double 85 conditions for a long time. At present, there are few reports on liquid silicone rubber that can be used as automobile lens material. SUMMARY

[0007] Based on the defects of the prior art, the purpose of the present application is to provide a yellowing-resistant high-transparency liquid silicone rubber and a preparation method thereof, which aims to make the liquid silicone rubber have high-transparency and excellent yellowing resistance under ultraviolet, high temperature and double 85 conditions, and is suitable for application as an automobile lens material.

[0008] In order to achieve the above purpose, the technical solution adopted by the present application is:

[0009] In the first aspect, the present application provides a yellowing-resistant high-transparency liquid silicone rubber, which comprises A component and B component. The A component comprises the following raw materials in mass fraction: base glue 50-80 parts, catalyst 0.5-1 part. The B component comprises the following raw materials in mass fraction: base glue 50-80 parts, hydrogen-containing silicone oil 20-30 parts, inhibitor 0.01-1 part.

[0010] In some preferred embodiments, the base glue comprises the following raw materials in mass fraction: vinyl silicone oil 100 parts, white carbon black 3-8 parts, silicone resin 25-35 parts, modifier A 0.5-1 part, and modifier B 0.5-1 part.

[0011] In some preferred embodiments, the vinyl silicone oil comprises vinyl silicone oil A and vinyl silicone oil B.

[0012] Preferably, the molecular structure formula of the vinyl silicone oil A is as follows:

[0013] (CH2=CH)(CH3)2SiO[(CH3)2SiO] m [(CH2=CH)(CH3)SiO] n Si(CH3)2(CH2=CH).

[0014] Preferably, the vinyl silicone oil A has a vinyl content of 0.25-0.65 mmol / g and a viscosity of 500-1500 cP at 25°C.

[0015] Preferably, the vinyl silicone oil B has a molecular structure as follows: (CH2=CH)(CH3)2SiO[(CH3)2SiO] n Si(CH3)2(CH=CH2).

[0016] Preferably, the mass ratio of the vinyl silicone oil A and the vinyl silicone oil B is 3-6:1-3.

[0017] The present application uses the vinyl silicone oil A and the vinyl silicone oil B with different structures to improve the cross-linking degree of the liquid silicone rubber while avoiding the appearance of bubbles after curing, thereby improving the light transmittance.

[0018] Preferably, the specific surface area of the white carbon black is 100-200 m 2 / g.

[0019] Preferably, the silicone resin comprises a sheet-shaped silicone resin and a spherical silicone resin.

[0020] Preferably, the sheet-shaped silicone resin has a silicon hydroxyl content of 5-6 wt% and a phenyl / methyl ratio of 0.6-1.3:1.

[0021] Preferably, the spherical silicone resin is polymethylsilsesquioxane with an average particle size of 2-6 μm.

[0022] Preferably, the mass ratio of the sheet-shaped silicone resin and the spherical silicone resin is 1-2:0.1-0.2.

[0023] In the prior art, MQ resin is often used to replace part of the white carbon black to improve the light transmittance of the liquid silicone rubber. However, the present inventors found in the experiment that the liquid silicone rubber obtained by using MQ resin has poor yellowing resistance and discoloration after long-time ultraviolet lamp irradiation, double 85 test and 180°C high temperature test. The present inventors accidentally found that the use of sheet-shaped silicone resin and spherical silicone resin to replace white carbon black not only effectively reduces the amount of white carbon black, but also makes the liquid silicone rubber have optical-grade light transmittance, and has excellent yellowing resistance without discoloration after long-time ultraviolet lamp irradiation, double 85 test and 180°C high temperature test.

[0024] The types and specifications of the sheet-shaped silicone resins and the spherical silicone resins from different manufacturers on the market are different. The inventors have accidentally found that when the spherical silicone resin is polymethylsilsesquioxane and the silicon hydroxyl content of the sheet-shaped silicone resin is 5-6 wt% and the phenyl / methyl ratio is 0.6-1.3:1, the obtained liquid silicone rubber has excellent yellowing resistance. This may be because, on the one hand, the polymethylsilsesquioxane and the sheet-shaped silicone resin with a small phenyl / methyl ratio can jointly act with the vinyl silicone oil to optimize the molecular structure and form a physical barrier, thereby improving the yellowing resistance of the liquid silicone rubber under long-term ultraviolet light irradiation, double 85 test and 180℃ condition.

[0025] Preferably, the modifier A is hexamethyldisilazane.

[0026] Preferably, the modifier B has the following structure:

[0027]

[0028] In order to improve the dispersibility of the white carbon black in the base rubber, it is necessary to modify it with a modifier. The inventors have found in the test process that when only hexamethyldisilazane or hexamethyldisilazane and vinyl dimethyl ethoxy silane are used as the modifier and 2,6-di-tert-butyl-4-methyl phenol is added as the modifier, the obtained liquid silicone rubber not only cannot reach a transparency rate of 94% or above, but also appears discoloration under long-term ultraviolet light irradiation, double 85 test and 180℃ condition. However, only when hexamethyldisilazane and vinyl dimethyl ethoxy silane are used as the modifier together, the obtained liquid silicone rubber does not appear discoloration after long-term ultraviolet light irradiation, double 85 test and 180℃ high temperature test.

[0029] In addition, the inventors have found in the test process that when the addition amount of the modifier B is less than 0.5 parts, discoloration appears after long-term ultraviolet light irradiation, double 85 test and 180℃ high temperature test due to the small addition amount. When the addition amount of the modifier B is more than 1 part, discoloration also appears after long-term ultraviolet light irradiation, double 85 test and 180℃ high temperature test. This may be due to the presence of amino groups in the modifier B. Therefore, it is necessary to strictly control the addition amount of the modifier B.

[0030] In some preferred embodiments, the preparation method of the base rubber comprises the following steps: mixing and stirring the vinyl silicone oil, the white carbon black, the silicone resin, the modifier A and the modifier B, kneading at 25-30℃ for 1-2h, increasing the temperature to 110-120℃ and kneading for 1-2h, increasing the temperature to 150-160℃ and kneading under vacuum for 1-2h, to obtain the base rubber.

[0031] In some preferred embodiments, the catalyst is a Karstedt platinum gold catalyst.​

[0032] Preferably, the platinum concentration in the Karstedt's platinum catalyst is 2000-3000 ppm.

[0033] In some preferred embodiments, the hydrogen-containing silicone oil is a terminal hydrogen-containing silicone oil.

[0034] Preferably, the hydrogen-containing silicone oil has a hydrogen content of 0.1-0.15%, and a viscosity of 17-25 cP at 25°C.

[0035] In some preferred embodiments, the inhibitor is selected from at least one of 1,4-butynediol and 1-ethynyl-1-cyclohexanol.

[0036] In a second aspect, the present application provides a preparation method of the yellowing-resistant high-transmittance liquid silicone rubber described above, comprising the following steps: adding a catalyst to a base rubber, and mixing to obtain component A; adding a hydrogen-containing silicone oil and an inhibitor to the base rubber, and mixing to obtain component B.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] 1. The present application uses vinyl silicone oil A and vinyl silicone oil B with different structures to improve the crosslinking degree of the liquid silicone rubber while avoiding the appearance of bubbles after curing, thereby improving the light transmittance thereof.

[0039] 2. The present application uses sheet-shaped silicone resin and spherical silicone resin to replace white carbon black, which not only effectively reduces the amount of white carbon black, so that the liquid silicone rubber has an optical-grade light transmittance, but also does not appear discoloration after long-time ultraviolet lamp irradiation, double 85 test and 180°C high-temperature test, and has excellent yellowing resistance.

[0040] 3. The present application controls the spherical silicone resin to be polymethylsilsesquioxane, and the silicon hydroxyl content of the sheet-shaped silicone resin to be 5-6 wt%, and the phenyl / methyl ratio to be 0.6-1.3:1, thereby improving the yellowing resistance of the liquid silicone rubber.

[0041] 4. The present application uses hexamethyldisilazane and as a modifier together, so that the liquid silicone rubber does not appear discoloration after long-time ultraviolet lamp irradiation, double 85 test and 180°C high-temperature test.

[0042] 5. The liquid silicone rubber of the present application also has good mechanical properties. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 A physical picture of a sheet prepared using the liquid silicone rubber of Example 1 of the present application after being placed at 180°C for 360h;

[0044] Figure 2 The physical picture of the sheet prepared by using the liquid silicone rubber of embodiment 4 of the present application after being placed at 180℃ for 360h. DETAILED DESCRIPTION

[0045] In order to make the skilled in the art more clearly understand the technical solutions described in the present application, the following examples are listed for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the present application.

[0046] The raw materials, reagents or devices used in the following examples and comparative examples are commercially available or can be obtained by known methods unless otherwise specified.

[0047] Base rubber A:

[0048] Composed of the following raw materials in mass fraction:

[0049] Vinyl silicone oil 100 parts, white carbon black 5 parts, silicone resin 30 parts, modifier A 0.6 parts, modifier B 0.6 parts.

[0050] The vinyl silicone oil is vinyl silicone oil A and vinyl silicone oil B in a mass ratio of 5:3.

[0051] The molecular structure formula of the vinyl silicone oil A is as follows:

[0052] (CH2=CH)(CH3)2SiO[(CH3)2SiO] m [(CH2=CH)(CH3)SiO] n Si(CH3)2(CH2=CH), vinyl content 0.509-0.623 mmol / g, viscosity 1300±70 cP, 25℃, Shandong Dayi Chemical Co., Ltd., Model: V421-1300.

[0053] The molecular structure formula of the vinyl silicone oil B is as follows:

[0054] (CH2=CH)(CH3)2SiO[(CH3)2SiO] n Si(CH3)2(CH=CH2), vinyl content 0.040-0.081 mmol / g, viscosity 5000±250 cP, 25℃, Shandong Dayi Chemical Co., Ltd., Model: V401-5000.

[0055] The specific surface area of the white carbon black is 150-170 m 2 / g, Jin Sanjiang (Zhaoqing) Silicon Material Co., Ltd., Model: BACOSIL C366.

[0056] The silicone resin is a flaky silicone resin and a spherical silicone resin with a mass ratio of 1:0.1.

[0057] The silicon hydroxyl content of the flaky silicone resin is 5 wt%, and the phenyl / methyl ratio is 1.3:1, Shanghai Boting Chemical Co., Ltd., DOWSIL TM RSN-0233.

[0058] The spherical silicone resin is polymethylsilsesquioxane with an average particle size of 2 μm, Jiujiang Youmei New Material Technology Co., Ltd., Model: YGF-102.

[0059] The modifier A is hexamethyldisilazane.

[0060] The structural formula of the modifier B is as follows:

[0061] Guangzhou Haoyi New Material Technology Co., Ltd., Model: Shin-Etsu TMPS-E.

[0062] The preparation method of the above base glue A comprises the following steps: mixing and stirring the vinyl silicone oil, the white carbon black, the silicone resin, the modifier A and the modifier B, kneading at 25 °C for 2 h, increasing the temperature to 20 °C and kneading for 2 h, increasing the temperature to 160 °C, and kneading under vacuum for 2 h to obtain the base glue.

[0063] Base glue B

[0064] The only difference between the base glue A and the base glue B is that the base glue B is composed of the following raw materials in mass fraction: 100 parts of the vinyl silicone oil, 3 parts of the white carbon black, 32 parts of the silicone resin, 0.5 parts of the modifier A and 0.5 parts of the modifier B; the rest are the same.

[0065] Base glue C

[0066] The only difference between the base glue A and the base glue C is that the modifier B is replaced by the same mass of the modifier A; the rest are the same.

[0067] Base glue D

[0068] The only difference between the base glue A and the base glue D is that the modifier B is replaced by the same mass of the vinyl dimethylethoxysilane, and 1 mass part of 2,6-di-tert-butyl-4-methylphenol is additionally added; the rest are the same.

[0069] Base glue E

[0070] The only difference between the base glue A and the base glue E is that the mass fraction of the modifier B is 0.4 parts; the rest are the same.

[0071] Base glue F

[0072] The only difference between the base glue A and the base glue F is that the mass fraction of the modifier B is 1.1 parts; the rest are the same.

[0073] Base G

[0074] The only difference from base adhesive A is that the spherical silicone resin is replaced with an equal mass of methyl MQ resin (Shandong Dayi Chemical Co., Ltd., model: DY-MQ803); all other aspects are the same.

[0075] Base adhesive H

[0076] The only difference from base adhesive A is that the spherical silicone resin is replaced with an equal mass of vinyl silicone resin (Jiujiang Runhe Synthetic Materials Co., Ltd., model: RH-S0826H); all other aspects are the same.

[0077] Base I

[0078] The only difference from base adhesive A is that the silanol content of the sheet-like silicone resin is 6 wt%, and the phenyl / methyl ratio is 2:1. (Shanghai Boding Chemical Co., Ltd., Model: DOWSIL) TM RSN-0220; all others are the same.

[0079] Base adhesive J

[0080] The only difference from base adhesive A is that the sheet-like silicone resin is a hydroxyl-terminated phenylsilsesquioxane with a silanol content of 6 wt%. (Shanghai Boding Chemical Co., Ltd., Model: DOWSIL) TM RSN-0217; all others are the same.

[0081] Example 1

[0082] A liquid silicone rubber with high light transmittance and resistance to yellowing includes component A and component B. Component A includes the following raw materials in parts by weight: 60 parts of base rubber A and 0.6 parts of catalyst.

[0083] Component B comprises the following raw materials in parts by weight: 60 parts of base adhesive A, 25 parts of hydrogen-containing silicone oil, and 0.3 parts of inhibitor.

[0084] The catalyst is a Castells platinum catalyst with a platinum concentration of 2000 ppm, manufactured by Shanghai Silicon Power Materials Co., Ltd.

[0085] The hydrogen-containing silicone oil is an end-hydrogen silicone oil with a hydrogen content of 0.11-0.13%, a viscosity of 17-22 cP, and a temperature of 25°C. It is manufactured by Ningbo Runhe High-Tech Materials Technology Co., Ltd., and its model number is RH-H45.

[0086] The inhibitor is 1-ethynyl-1-cyclohexanol.

[0087] The preparation method of the above-mentioned liquid silicone rubber with high light transmittance and resistance to yellowing includes the following steps: adding a catalyst to base rubber A and mixing to obtain component A; adding hydrogen-containing silicone oil and inhibitor to base rubber A and mixing to obtain component B.

[0088] Example 2

[0089] The only difference between Example 1 and Example 2 is that Base Glue A is replaced by Base Glue B in the same mass fraction; the rest is the same.

[0090] Example 3

[0091] The only difference between Example 1 and Example 3 is that Base Glue A is replaced by Base Glue C in the same mass fraction; the rest is the same.

[0092] Example 4

[0093] The only difference between Example 1 and Example 4 is that Base Glue A is replaced by Base Glue D in the same mass fraction; the rest is the same.

[0094] Example 5

[0095] The only difference between Example 1 and Example 5 is that Base Glue A is replaced by Base Glue E in the same mass fraction; the rest is the same.

[0096] Example 6

[0097] The only difference between Example 1 and Example 6 is that Base Glue A is replaced by Base Glue F in the same mass fraction; the rest is the same.

[0098] Example 7

[0099] The only difference between Example 1 and Example 7 is that Base Glue A is replaced by Base Glue G in the same mass fraction; the rest is the same.

[0100] Example 8

[0101] The only difference between Example 1 and Example 8 is that Base Glue A is replaced by Base Glue H in the same mass fraction; the rest is the same.

[0102] Example 9

[0103] The only difference between Example 1 and Example 9 is that Base Glue A is replaced by Base Glue I in the same mass fraction; the rest is the same.

[0104] Example 10

[0105] The only difference between Example 1 and Example 10 is that Base Glue A is replaced by Base Glue J in the same mass fraction; the rest is the same.

[0106] Performance test:

[0107] The A component and the B component of Example 1-Example 10 are mixed uniformly in a mass fraction of 1:1, degassed, and vulcanized at 120°C for 1h to obtain a sheet with a thickness of 6mm. The sheet is subjected to the following performance tests:

[0108] 1. Optical performance:

[0109] Transmittance: The transmittance was tested by spectrophotometer at 450 nm wavelength;

[0110] 2. Anti-yellowing property

[0111] (1) Using UVA-340m ultraviolet lamp irradiation, the intensity was 60 W / m 2 , the temperature was 30℃, after 360h, the spectrophotometer was used to measure the yellowing index ΔYi;

[0112] (2) After 3000h at 85℃, 85% humidity, the spectrophotometer was used to measure the yellowing index ΔYi;

[0113] (3) After 360h at 180℃, the spectrophotometer was used to measure the yellowing index ΔYi;

[0114] The following standards were recorded:

[0115] 0 grade: no discoloration, ΔYi≤1.5;

[0116] 1 grade: very slight discoloration, 1.6<ΔYi≤3.0;

[0117] 2 grade: slight discoloration, 3.1<ΔYi≤6.0;

[0118] 3 grade: obvious discoloration, 6.1<ΔYi≤9.0;

[0119] 4 grade: larger discoloration, 9.1<ΔYi≤12.0;

[0120] 5 grade: severe discoloration, 12.0<ΔYi.

[0121] The results are shown in Table 1 below.

[0122] Table 1 Performance test results of liquid silicone rubber of Example 1-Example 8

[0123]

[0124]

[0125] From Table 1, it can be seen that:

[0126] The liquid silicone rubber provided by Example 1 and Example 2 has high transmittance and excellent anti-yellowing property, and has no discoloration after 360h of ultraviolet light irradiation, 3000h of double 85 test and 360h of 180℃ test;

[0127] The replacement of the modifier B in the base glue of Example 3 with the same amount of modifier A, i.e. the absence of modifier A, results in liquid silicone rubber which not only causes the light transmittance to decrease, but also causes the UV resistance, double 85 resistance and high temperature yellowing resistance to decrease significantly;

[0128] The replacement of the modifier B in the base glue of Example 4 with the same amount of vinyl dimethyl ethoxy silane and the additional addition of 1 part by mass of 2, 6-di-tert-butyl-4-methyl phenol results in liquid silicone rubber which has slightly improved light transmittance compared with the liquid silicone rubber obtained in Example 3, but still appears yellowing after the UV resistance, double 85 resistance and high temperature resistance tests, indicating that the modifier A has a significant influence on the light transmittance and yellowing resistance of the liquid silicone rubber.

[0129] The addition amount of the modifier B in the base glue of Example 5 is lower than the range defined in the present application, and the addition amount of the modifier B in the base glue of Example 6 is higher than the range defined in the present application, resulting in liquid silicone rubber which has little change in light transmittance, but the UV resistance, double 85 resistance and high temperature yellowing resistance of which all decrease;

[0130] Examples 5 and 6 show that the addition amount of the modifier B in the base glue influences the UV resistance, double 85 resistance and high temperature yellowing resistance of the liquid silicone rubber, and lower or higher than the range defined in the present application will both result in poor performance.

[0131] The replacement of the spherical silicone resin in the base glue of Example 7 with the same amount of methyl MQ resin results in liquid silicone rubber which has little change in light transmittance, but the UV resistance, double 85 resistance and high temperature yellowing resistance of which decrease;

[0132] The replacement of the spherical silicone resin in the base glue of Example 8 with the same amount of vinyl silicone resin results in liquid silicone rubber which has little change in light transmittance, but the UV resistance, double 85 resistance and high temperature yellowing resistance of which decrease;

[0133] Examples 7 and 8 show that the spherical silicone resin used in the base glue can significantly improve the yellowing resistance of the liquid silicone rubber compared with the silicone resin in the prior art.

[0134] The silicon hydroxyl content of the flaky silicone resin in Example 9 is 6wt%, and the phenyl / methyl ratio is 2:1, and the flaky silicone resin in Example 10 is a hydroxyl-terminated phenyl silsesquioxane with a silicon hydroxyl content of 6wt%, resulting in liquid silicone rubber which has little change in light transmittance, but the UV resistance, double 85 resistance and high temperature yellowing resistance of which decrease;

[0135] Examples 9 and 10 show that the phenyl / methyl ratio and composition of the flaky silicone resin in the base glue also affect the yellowing resistance of the liquid silicone rubber.

[0136] 3. Mechanical properties:

[0137] (1) Tensile strength: tested according to GB / T 528-2009;

[0138] (2) Tear strength: tested according to GB / T 529-2009;

[0139] (3) Elongation at break: tested according to GB / T 528-2009; the results are shown in Table 2.

[0140] Table 2: Test results of the properties of the liquid silicone rubber of Example 1-Example 2

[0141]

[0142] As can be seen from Table 2, the liquid silicone rubber of Example 1 and Example 2 also has good mechanical properties.

[0143] Finally, it should be noted that the above content is only used to illustrate the technical solutions of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A liquid silicone rubber with high light transmittance and resistance to yellowing, characterized in that, The product comprises component A and component B. Component A includes the following raw materials: base adhesive and catalyst; component B includes the following raw materials: base adhesive, hydrogen-containing silicone oil, and inhibitor. The base adhesive comprises the following raw materials in parts by weight: 100 parts vinyl silicone oil, 3-8 parts silica, 25-35 parts silicone resin, 0.5-1 part modifier A, and 0.5-1 part modifier B; The silicone resin comprises sheet-like silicone resin and spherical silicone resin in a mass ratio of 1-2:0.1-0.2; The sheet-like silicone resin has a silanol content of 5-6 wt% and a phenyl / methyl ratio of 0.6-1.3:1; the spherical silicone resin is polymethylsilsesquioxane with an average particle size of 2-6 μm. The modifier A is hexamethyldisilazane; The structural formula of the modifier B is as follows: .

2. The liquid silicone rubber with high light transmittance and resistance to yellowing according to claim 1, characterized in that, Component A comprises the following raw materials in parts by weight: 50-80 parts base adhesive and 0.5-1 parts catalyst; Component B comprises the following raw materials in parts by weight: 50-80 parts base adhesive, 20-30 parts hydrogen-containing silicone oil and 0.01-1 parts inhibitor.

3. The liquid silicone rubber with high light transmittance and resistance to yellowing according to claim 2, characterized in that, The vinyl silicone oil includes vinyl silicone oil A and vinyl silicone oil B; The molecular structural formula of the vinyl silicone oil A is as follows: (CH2=CH)(CH3)2SiO[(CH3)2SiO] m [(CH2=CH)(CH3)SiO] n Si(CH3)2(CH2=CH); The molecular structure of the vinyl silicone oil B is as follows: (CH2=CH)(CH3)2SiO[(CH3)2SiO] n Si(CH3)2(CH=CH2).

4. The liquid silicone rubber with high light transmittance and resistance to yellowing according to claim 3, characterized in that, The vinyl silicone oil A has a vinyl content of 0.25-0.65 mmol / g, a viscosity of 500-1500 cP, and operates at 25°C.

5. The liquid silicone rubber with high light transmittance and resistance to yellowing according to claim 3, characterized in that, The vinyl silicone oil B has a vinyl content of 0.040-0.081 mmol / g, a viscosity of 5000±250 cP, and a temperature of 25℃.

6. The liquid silicone rubber with high light transmittance and resistance to yellowing according to any one of claims 1-5, characterized in that, The preparation method of the base adhesive includes the following steps: mixing and stirring vinyl silicone oil, silica, silicone resin, modifier A and modifier B, kneading at 25-30℃ for 1-2 hours, heating to 110-120℃ and kneading for 1-2 hours, heating to 150-160℃ and kneading under vacuum for 1-2 hours to obtain the base adhesive.

7. The liquid silicone rubber with high light transmittance and resistance to yellowing according to claim 6, characterized in that, The hydrogen-containing silicone oil is an end-hydrogen-containing silicone oil; the hydrogen content of the end-hydrogen-containing silicone oil is 0.1-0.15%, the viscosity is 17-25 cP, and the temperature is 25°C.

8. The method for preparing the liquid silicone rubber with high light transmittance and resistance to yellowing as described in any one of claims 1-7, characterized in that, The process includes the following steps: adding a catalyst to the base adhesive and mixing to obtain component A; adding hydrogen-containing silicone oil and an inhibitor to the base adhesive and mixing to obtain component B.

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