Addition type liquid silicone rubber with high refractive index and low haze and preparation method thereof

Abstract

The invention relates to the technical field of liquid silicone rubber, in particular to high-refractive-index low-haze addition type liquid silicone rubber and a preparation method thereof, and the high-refractive-index low-haze addition type liquid silicone rubber is prepared from vinyl silicone oil, a catalyst, an inhibitor, a cross-linking agent, hydrophobic white carbon black, a white carbon black surface treating agent and the like. According to the method, by regulating and controlling the surface state of the white carbon black and the refractive index of the silicone oil, the addition type liquid silicone rubber with high refractive index, high light transmittance and low haze at the same time is realized, and the addition type liquid silicone rubber is good in mechanical property and fluidity, can adapt to continuous extrusion production, and is suitable for large-scale production. After vulcanization, the Shore A hardness is 50-53, the light transmittance is 94% or above, the haze is lower than 3%, the refractive index reaches 1.54 or above, and the polyurethane resin can be applied to the fields of optical devices, LED packaging and the like.

Description

Technical Field

[0001] The invention relates to the technical field of liquid silicone rubber, in particular to an addition-type liquid silicone rubber with high refractive index and low haze and a preparation method thereof. Background Art

[0002] Addition-type liquid silicone rubber has good stability, low heat shrinkage, simple vulcanization process, no by-products during vulcanization, strong mechanical properties, etc., so it has great application prospects in the field of optoelectronic devices. Traditional epoxy resin materials are prone to yellowing and reduced light transmittance during use in the field of optical electronic devices such as LEDs, which seriously affects their application. The high transparency of liquid silicone rubber not only enables it to meet the transmittance requirements of optical electronic devices, but also its high high temperature and ultraviolet stability can ensure the normal operation of the device for a long time. However, the refractive index of traditional liquid silicone rubber is between 1.4 and 1.45, which is difficult to meet the high refractive index performance requirements of high-end optoelectronic device packaging materials. The high refractive index can reduce the loss of light in the material, make the light more uniform, and improve the brightness and efficiency of optoelectronic devices. Therefore, improving the performance and process of addition-type liquid silicone rubber so that it has high transmittance, high refractive index and low haze performance has become an urgent problem to be solved in this field.

[0003] For achieving high light transmittance of liquid silicone rubber, the existing technical means can be divided into three categories: 1) Most of the hydroxyl groups on the surface of silica are treated with silica surface treatment agents. Surface treatment agents for silica mainly include alcohol, cyclosiloxane, zinc stearate, hexamethyldisilazane, etc. By treating the hydroxyl groups on the hydrophilic surface of silica, it has a certain lipophilicity and is more evenly dispersed in silicone oil, thereby improving the light transmittance of liquid silicone rubber; however, although excessive treatment of the surface of silica can improve its dispersibility, it will cause a significant decrease in the mechanical properties of the rubber after vulcanization. 2) Replacing silica with vinyl silicone resin can improve the light transmittance of the rubber and improve the mechanical properties of the rubber; however, completely replacing silica with vinyl silicone resin will greatly increase production costs and make it difficult to meet the low-price market demand. 3) Using silica with a high specific surface area can improve the light transmittance of liquid silicone rubber; however, silica is more likely to aggregate in the rubber and will cause the viscosity of the rubber to rise sharply. 4) Using high-quality raw materials, such as high-quality vinyl silicone oil, white carbon black and other raw materials, can appropriately reduce the yellowing and uniformity of the rubber; however, this method has high requirements on raw materials, has limitations, and the price and selection space of high-quality raw materials are small.

[0004] For achieving high refractive index of liquid silicone rubber, existing technical means can be divided into three categories: 1) By adding phenyl vinyl silicone oil, the refractive index of the rubber can be increased. Phenyl has the characteristics of high refractive index and can improve the rubber's resistance to high and low temperatures and ultraviolet radiation; however, the refractive index of high phenyl silicone oil is quite different from that of white carbon black, which will lead to a decrease in the transmittance of the obtained rubber and an increase in haze. 2) The use of phenyl-containing hydrogen-containing silicone oil can also appropriately increase the refractive index of the rubber; however, the proportion of hydrogen-containing silicone oil in the rubber is small, and the increase in the refractive index of the rubber is small. 3) Adding phenyl-containing vinyl silicone resin can increase the refractive index of the rubber and play a role in improving mechanical properties; however, adding a large amount will lead to a large increase in costs.

[0005] At present, researchers have achieved the properties of "high transmittance", "high refractive index" and "low haze" of liquid silicone rubber. However, it is worth noting that it is difficult to achieve liquid silicone rubber with the above properties at the same time. For example, in order to achieve "high transmittance" and "low haze", some patents adopt the following technical route: using high specific surface area white carbon black and increasing the amount of white carbon black surface treatment agent to improve the compatibility between white carbon black and silicone oil, so that the overall material has good transmittance and low haze. However, due to the use of high specific surface area carbon black, the material viscosity is high and the refractive index is low. There is also a solution to use silicone resin to replace part of the white carbon black. Although this method can reduce the viscosity of the material and improve the optical performance, the solution is costly and the material has a low refractive index. In order to improve the refractive index of the material, some patents adopt the following technical route: using high-refractive-index phenyl vinyl silicone oil as raw material to replace terminal vinyl methyl silicone oil, or adding phenyl-containing silicone resin. This method can significantly improve the refractive index of the material. However, the high-refractive-index phenyl vinyl silicone oil or silicone resin used has a large difference in refractive index with that of white carbon black, which causes more scattering of light inside the material, resulting in a significant increase in the haze of the rubber.

[0006] In summary, we disclose an addition-type liquid silicone rubber with high refractive index and low haze and a preparation method thereof to solve the technical problem. Summary of the invention

[0007] In order to solve the above problems, this patent provides a high refractive index and low haze addition type liquid silicone rubber, which can be vulcanized and molded at 100°C. After vulcanization, the transparency of the rubber can reach more than 94%, the refractive index can reach more than 1.54, and the haze is less than 3%.

[0008] A high-refractive-index and low-haze addition-type liquid silicone rubber and a preparation method thereof, characterized in that the addition-type liquid silicone rubber consists of component A and component B.

[0009] The component A is composed of 15 to 50 parts of base rubber, 0.001 to 0.5 parts of catalyst, 0.3 to 3 parts of polyvinyl silicone oil and 1 to 20 parts of inhibitor.

[0010] The B component consists of 15 to 50 parts of base rubber, 1 to 20 parts of cross-linking agent, and 0.01 to 1 part of tackifier.

[0011] The base rubber of component A and component B is composed of 10 to 50 parts of hydrophobic white carbon black, 10 to 50 parts of vinyl silicone oil, 0 to 15 parts of white carbon black surface treatment agent and 1 to 5 parts of water.

[0012] The surface treatment method of hydrophobic silica is as follows: the hydrophobic silica needs to be treated during the preparation of the base rubber. According to the formula, the hydrophobic silica, silica surface treatment agent, vinyl silicone oil and deionized water are added into the kneader in sequence, stirred at room temperature for 1 to 3 hours, then heated at 70 to 200°C for 1 to 5 hours, and then vacuum treated at -0.1 MPa for 1 hour to obtain the base rubber.

[0013] The vinyl silicone oil is at least one of vinyl-terminated polysiloxane and vinyl-terminated phenyl polysiloxane.

[0014] Another technical solution of the present invention is to make the modified hydrophobic silica and silicone oil (vinyl silicone oil) have extremely close refractive indices by treating the silica surface with a surface treatment agent. The difference in refractive index between the modified hydrophobic silica and silicone oil is controlled to be less than 0.02. At the same time, by introducing long-chain polysiloxane and vinyl groups on the surface of silica, the compatibility between silica and silicone oil is improved.

[0015] The white carbon black has a specific surface area of ​​100 to 400 m 2 / g of hydrophobic silica; in the process of base rubber preparation, the silica surface is modified by a silica surface treatment agent to obtain modified hydrophobic silica.

[0016] The white carbon black surface treatment agent is selected from at least one of 1,3-biphenyltetramethyldisilazane, ethoxytriphenylsilane, methoxytriphenylsilane, methyldiphenylethoxysilane, methyldiphenylmethoxysilane, ethoxydimethyl (phenyl) silane, methoxydimethyl (phenyl) silane, and mono-terminated hydroxyl silicone oil.

[0017] The catalyst is a 100-20000 ppm Custer catalyst, and the solvent is a vinyl-terminated silicone oil with a viscosity of 300-800 mPa.s.

[0018] The polyvinyl silicone oil is a polyvinyl silicone oil with a vinyl content of 0.2 to 1.5%; The crosslinking agent is at least one of a side hydrogen-containing polysiloxane having a hydrogen content of 0.45% to 1.2% and a terminal hydrogen-containing polysiloxane having a hydrogen content of 0.02% to 0.2%; The inhibitor is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol or tert-butanol; The tackifier is at least one of 3-glycidylpropyltrimethoxysilane, methyl trimethoxyacetate, ethyl triethoxyacetate, triethoxysilane, and trimethoxysilane.

[0019] The preferred specific surface area of ​​the hydrophobic white carbon black is 300 m 2 / g of hydrophobic fumed silica, and the hydrophobic fumed silica is subjected to the above-mentioned surface modification treatment. The preferred surface treatment agent for silica is methyl diphenylethoxysilane, 300 viscosity single-end hydroxy silicone oil, vinyl dimethylethoxysilane, 1,3-biphenyl tetramethyl disilazane, ethoxy triphenyl silane. The treatment method is the same as above.

[0020] The preferred vinyl-terminated polysiloxane is vinyl-terminated polysiloxane with a viscosity of 10000-15000 mPa.s and phenylvinyl polysiloxane with a viscosity of 1000 mPa.s, a phenyl content of 45 wt% and a vinyl content of 0.65 wt%.

[0021] Preferably, the catalyst is 20000 ppm of Custer catalyst.

[0022] Preferably, the polyvinyl silicone oil is a polyvinyl silicone oil with a vinyl content of 1.22%.

[0023] Preferably, the crosslinking agent is a hydrogen-containing silicone oil having a hydrogen content of 0.45 to 1.2%.

[0024] Preferably the inhibitor is isopropanol.

[0025] The preferred viscosity of the tackifier is 3-glycidylpropyltrimethoxysilane.

[0026] Based on the above technical solution, the technical effects achieved by the present invention are: The present invention optimizes the liquid silicone rubber formula and process to obtain an addition-type liquid silicone rubber with high refractive index and low haze. The addition-type liquid silicone rubber has the characteristics of low viscosity, high light transmittance, high refractive index, low haze, and good mechanical properties. It can meet most LED packaging requirements and has great market value. The test results show that the AB glue of the present invention can be operated for 48 hours after mixing, the vulcanization temperature is 100°C, the initial viscosity after mixing is 240000-270000 mPa.s, the Shore hardness after vulcanization is 50-53A, the light transmittance is above 94%, more preferably above 96%, more preferably above 98%, the haze is less than 3%, more preferably less than 3%, more preferably less than 1%, the refractive index is above 1.54, more preferably above 1.55, and more preferably can reach 1.57 or more.

[0027] Through the above technical solution, the present invention has the following technical effects: (1) The addition-type liquid silicone rubber solution provided by the present invention adjusts the phenyl content on the surface of hydrophobic silica and the refractive index of silicone oil so that the refractive indexes of the two are close to each other. The obtained material has a high refractive index and low haze.

[0028] (2) The addition-type liquid silicone rubber solution provided by the present invention introduces long-chain siloxane on the surface of hydrophobic silica, making the surface of hydrophobic silica close to the chemical properties of silicone oil, thereby improving the dispersion effect of hydrophobic silica in silicone oil, reducing the interface effect between hydrophobic silica and silicone oil, and improving the light transmittance of the material.

[0029] (3) The addition-type liquid silicone rubber solution provided by the present invention introduces vinyl groups on the surface of hydrophobic silica, so that it is linked to silicone oil through chemical bonds, thereby further reducing the interface effect between hydrophobic silica and silicone oil and improving the optical properties of the material.

[0030] (4) The addition type liquid silicone rubber solution provided by the present invention can achieve high light transmittance and low haze without using MQ silicone resin. The experimental results show that 300m 2 / g specific surface area of ​​hydrophobic silica can also reach a transmittance of over 98%. DETAILED DESCRIPTION

[0031] The object of the present invention is to provide an addition-type liquid silicone rubber with high refractive index and low haze to solve the problems raised in the above background technology.

[0032] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. The present invention provides preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0034] In order to solve the above technical problems, the present invention provides the following technical solutions: Example 1: A high refractive index and low haze addition type liquid silicone rubber and a preparation method thereof, the specific preparation steps are: Preparation of modified silica base rubber: 15 parts of vinyl-terminated long-chain polysiloxane with a viscosity of 10000 mPa·s (terminated vinyl polysiloxane), 15 parts of vinylphenyl polysiloxane with a viscosity of 1000 mPa·s (phenyl content of 45 wt%, vinyl content of 0.65 wt%), 14.5 parts of polysiloxane with a specific surface area of ​​300 m 2 / g of hydrophobic silica, silica surface treatment agent (1.7 parts of methyl diphenyl ethoxy silane), and 1.2 parts of deionized water are kneaded in a kneader for 1 hour until the materials are evenly dispersed, and the heating is turned on. When the material temperature reaches 120°C, it is mixed for 1 hour, and then vacuum treated for 1 hour. After the vacuum is ended, the heating is turned off to obtain a base rubber.

[0035] Preparation of component A: Add 20 parts of base rubber, 0.007 parts of 20000PPM Custer catalyst, 1 part of polyvinyl silicone oil with a vinyl content of 1.22%, and 2 parts of isopropanol into a planetary mixer and mix and stir for 2 hours at -0.1MPa; Preparation of component B: 20 ​​parts of base rubber, 3.2 parts of side hydrogenated silicone oil with a hydrogen content of 0.58%, and 0.02 parts of 3-glycidylpropyl trimethoxysilane were added into a planetary mixer and mixed and stirred at -0.1 MPa for 2 hours; Mix evenly in the ratio of component A: group B by mass fraction = 1:1. After degassing in a degassing machine for 30 minutes, take 70g of the evenly mixed sample and put it into the mold. Vulcanize it at 100°C for 10 minutes to obtain transparent silicone rubber. The product was tested for performance. After mixing, the sample had a viscosity of 272458mpa·s, a transmittance of 94.2%, a haze of 2.8%, a refractive index of 1.54, a hardness of 52, a tensile strength of 7.62Mpa, a tear strength of 23.45KN\m, and an elongation at break of 422%. The base rubber was translucent and not yellow.

[0036] Example 2: A high refractive index and low haze addition type liquid silicone rubber and a preparation method thereof, the specific preparation steps are: Preparation of modified silica base rubber: 15 parts of vinyl-terminated long-chain polysiloxane with a viscosity of 10000 mPa·s (terminated vinyl polysiloxane), 15 parts of vinylphenyl polysiloxane with a viscosity of 1000 mPa·s (phenyl content of 45 wt%, vinyl content of 0.65 wt%), 14.5 parts of polysiloxane with a specific surface area of ​​300 m 2 / g of hydrophobic silica, silica surface treatment agent (1.7 parts of methyl diphenyl ethoxy silane, 2.1 parts of 300 viscosity single-end hydroxy silicone oil), 1.2 parts of deionized water, knead in a kneader for 1 hour until the materials are evenly dispersed, turn on the heating, and when the material temperature reaches 120°C, mix for 1 hour, then vacuum treat for 1 hour, end the vacuum and turn off the heating to obtain the base rubber.

[0037] Preparation of component A: Add 20 parts of base rubber, 0.007 parts of 20000PPM Custer catalyst, 1 part of polyvinyl silicone oil with a vinyl content of 1.22%, and 2 parts of isopropanol into a planetary mixer and mix and stir for 2 hours at -0.1MPa; Preparation of component B: 20 ​​parts of base rubber, 3.2 parts of side hydrogenated silicone oil with a hydrogen content of 0.58%, and 0.02 parts of 3-glycidylpropyl trimethoxysilane were added into a planetary mixer and mixed and stirred at -0.1 MPa for 2 hours; Mix evenly in the ratio of component A: group B by mass fraction = 1:1. After degassing in a degassing machine for 30 minutes, take 70g of the evenly mixed sample and put it into the mold. Vulcanize it at 100°C for 10 minutes to obtain transparent silicone rubber. The product was tested for performance. After mixing, the sample had a viscosity of 251324mpa·s, a transmittance of 96.3%, a haze of 2.2%, a refractive index of 1.55, a hardness of 53, a tensile strength of 7.51Mpa, a tear strength of 27.95KN\m, and an elongation at break of 413%. The base rubber was translucent and not yellow.

[0038] Example 3: A high refractive index and low haze addition type liquid silicone rubber and a preparation method thereof, the specific preparation steps are as follows: Preparation of modified silica base rubber: 15 parts of vinyl-terminated long-chain polysiloxane with a viscosity of 10000 mPa·s ((terminated vinyl polysiloxane)), 15 parts of vinylphenyl polysiloxane with a viscosity of 1000 mPa·s (phenyl content of 45 wt%, vinyl content of 0.65 wt%), 14.5 parts of polysiloxane with a specific surface area of ​​300 m 2 / g of hydrophobic silica, silica surface treatment agent (1.7 parts of methyl diphenyl ethoxy silane, 2.1 parts of 300 viscosity single-end hydroxy silicone oil, 0.3 parts of vinyl dimethyl ethoxy silane), and 1.2 parts of deionized water are kneaded in a kneader for 1 hour until the materials are evenly dispersed, and the heating is turned on. When the material temperature reaches 120°C, it is mixed for 1 hour, and then vacuum treated for 1 hour. After the vacuum is ended, the heating is turned off to obtain a base rubber.

[0039] Preparation of component A: Add 20 parts of base rubber, 0.007 parts of 20000PPM Custer catalyst, 1 part of polyvinyl silicone oil with a vinyl content of 1.22%, and 2 parts of isopropanol into a planetary mixer and mix and stir for 2 hours at -0.1MPa; Preparation of component B: 20 ​​parts of base rubber, 3.2 parts of side hydrogenated silicone oil with a hydrogen content of 0.58%, and 0.02 parts of 3-glycidylpropyl trimethoxysilane were added into a planetary mixer and mixed and stirred at -0.1 MPa for 2 hours; Mix evenly in the ratio of component A: group B by mass fraction = 1:1. After degassing in a degassing machine for 30 minutes, take 70g of the evenly mixed sample and put it into the mold. Vulcanize it at 100°C for 10 minutes to obtain transparent silicone rubber. The product was tested for performance. After mixing, the sample had a viscosity of 241236mpa·s, a transmittance of 98.3%, a haze of 1.2%, a refractive index of 1.56, a hardness of 53, a tensile strength of 8.45Mpa, a tear strength of 34.58KN\m, and an elongation at break of 438%. The base rubber was translucent and not yellow.

[0040] Example 4: A high refractive index and low haze addition type liquid silicone rubber and a preparation method thereof, the specific preparation steps are: Preparation of modified silica base rubber: 12 parts of vinyl-terminated long-chain polysiloxane with a viscosity of 10000 mPa·s ((terminated vinyl polysiloxane)), 18 parts of vinyl phenyl polysiloxane with a viscosity of 1000 mPa·s (phenyl content of 45 wt%, vinyl content of 0.65 wt%), 14.5 parts of polysiloxane with a specific surface area of ​​300 m 2 / g of hydrophobic silica, silica surface treatment agent (1.7 parts of methyl diphenylethoxysilane, 2.1 parts of 300 viscosity single-end hydroxy silicone oil, 0.3 parts of vinyl dimethylethoxysilane, 0.2 parts of 1,3-biphenyltetramethyldisilazane), 1.2 parts of deionized water, knead in a kneader for 1 hour until the material is evenly dispersed, turn on the heating, when the material temperature reaches 120°C, mix for 1 hour, then vacuum treat for 1 hour, end the vacuum and turn off the heating to obtain the base rubber.

[0041] Preparation of component A: Add 20 parts of base rubber, 0.007 parts of 20000PPM Custer catalyst, 1 part of polyvinyl silicone oil with a vinyl content of 1.22%, and 2 parts of isopropanol into a planetary mixer and mix and stir for 2 hours at -0.1MPa; Preparation of component B: 20 ​​parts of base rubber, 3.2 parts of side hydrogenated silicone oil with a hydrogen content of 0.58%, and 0.02 parts of 3-glycidylpropyl trimethoxysilane were added into a planetary mixer and mixed and stirred at -0.1 MPa for 2 hours; Mix evenly in the ratio of component A: group B by mass fraction = 1:1. After degassing in a degassing machine for 30 minutes, take 70g of the evenly mixed sample and put it into the mold. Vulcanize it at 100°C for 10 minutes to obtain transparent silicone rubber. The product was tested for performance. After mixing, the sample had a viscosity of 249247mpa·s, a transmittance of 98.41%, a haze of 1.3%, a refractive index of 1.56, a hardness of 52, a tensile strength of 8.86Mpa, a tear strength of 36.48KN\m, and an elongation at break of 438%. The base rubber was translucent and not yellow.

[0042] Example 5: A high refractive index and low haze addition type liquid silicone rubber and a preparation method thereof, the specific preparation steps are: Preparation of modified silica base rubber: 11.2 parts of vinyl-terminated long-chain polysiloxane with a viscosity of 10000 mPa·s (terminated vinyl polysiloxane), 18.8 parts of vinyl phenyl polysiloxane with a viscosity of 1000 mPa·s (phenyl content of 45 wt%, vinyl content of 0.65 wt%), 14.5 parts of polysiloxane with a specific surface area of ​​300 m 2 / g of hydrophobic silica, silica surface treatment agent (1.7 parts of methyl diphenylethoxysilane, 2.7 parts of 300 viscosity single-end hydroxy silicone oil, 0.3 parts of vinyl dimethylethoxysilane, 0.25 parts of ethoxytriphenylsilane), 1.2 parts of deionized water, knead in a kneader for 1 hour until the materials are evenly dispersed, turn on the heating, when the material temperature reaches 120°C, mix for 1 hour, then vacuum treat for 1 hour, end the vacuum and turn off the heating to obtain the base rubber.

[0043] Preparation of component A: Add 20 parts of base rubber, 0.007 parts of 20000PPM Custer catalyst, 1 part of polyvinyl silicone oil with a vinyl content of 1.22%, and 2 parts of isopropanol into a planetary mixer and mix and stir for 2 hours at -0.1MPa; Preparation of component B: 20 ​​parts of base rubber, 3.2 parts of side hydrogenated silicone oil with a hydrogen content of 0.58%, and 0.02 parts of 3-glycidylpropyl trimethoxysilane were added into a planetary mixer and mixed and stirred at -0.1 MPa for 2 hours; Mix evenly in the ratio of component A: group B by mass fraction = 1:1. After degassing in a degassing machine for 30 minutes, take 70g of the evenly mixed sample and put it into the mold. Vulcanize it at 100°C for 10 minutes to obtain transparent silicone rubber. The product was tested for performance. After mixing, the sample had a viscosity of 269724mpa·s, a transmittance of 98.81%, a haze of 0.9%, a refractive index of 1.57, a hardness of 53, a tensile strength of 8.87Mpa, a tear strength of 38.48KN\m, and an elongation at break of 389%. The base rubber was translucent and not yellow.

[0044] Comparative Example 1: A high refractive index and low haze addition type liquid silicone rubber and a preparation method thereof, wherein the specific preparation steps are as follows: Preparation of modified silica base rubber: Take 30 parts of vinyl-terminated long-chain polysiloxane (terminated vinyl polysiloxane) with a viscosity of 10000mPa·s and 15 parts of polysiloxane with a specific surface area of ​​300m 2 / g of hydrophobic silica and 1.2 parts of deionized water are kneaded in a kneader for 1 hour until the materials are evenly dispersed, and the heating is turned on. When the material temperature reaches 120°C, it is mixed for 1 hour, and then vacuum treated for 1 hour. After the vacuum is ended, the heating is turned off to obtain a base rubber.

[0045] Preparation of component A: Add 20 parts of base rubber, 0.007 parts of 20000PPM Custer catalyst, 1 part of polyvinyl silicone oil with a vinyl content of 1.22%, and 2 parts of isopropanol into a planetary mixer and mix and stir for 2 hours at -0.1MPa; Preparation of component B: 20 ​​parts of base rubber, 3.2 parts of side hydrogenated silicone oil with a hydrogen content of 0.58%, and 0.02 parts of 3-glycidylpropyl trimethoxysilane were added into a planetary mixer and mixed and stirred at -0.1 MPa for 2 hours; Mix evenly in the ratio of component A: group B by mass fraction = 1:1, degas in the degasser for 30 minutes, take 70g of the evenly mixed sample and put it into the mold, vulcanize it at 100℃ for 10 minutes to obtain transparent silicone rubber. After mixing, the sample has a viscosity of 357345mpa·s, a transmittance of 92.8%, a haze of 4.1%, a refractive index of 1.43, a hardness of 50, a tensile strength of 5.21Mpa, a tear strength of 15.48KN\m, and an elongation at break of 442%. The base rubber is bright and not yellow.

[0046] Comparative Example 2: A high refractive index and low haze addition type liquid silicone rubber and a preparation method thereof, wherein the specific preparation steps are as follows: Preparation of modified silica base rubber: Take 30 parts of vinyl-terminated long-chain polysiloxane (terminated vinyl polysiloxane) with a viscosity of 10000mPa·s and 15 parts of polysiloxane with a specific surface area of ​​300m 2 / g of hydrophobic silica, silica surface treatment agent (1.7 parts of methyl diphenyl ethoxy silane), and 1.2 parts of deionized water are kneaded in a kneader for 1 hour until the materials are evenly dispersed, and the heating is turned on. When the material temperature reaches 120°C, it is mixed for 1 hour, and then vacuum treated for 1 hour. After the vacuum is ended, the heating is turned off to obtain a base rubber.

[0047] Preparation of component A: Add 20 parts of base rubber, 0.007 parts of 20000PPM Custer catalyst, 1 part of polyvinyl silicone oil with a vinyl content of 1.22%, and 2 parts of isopropanol into a planetary mixer and mix and stir for 2 hours at -0.1MPa; Preparation of component B: 20 ​​parts of base rubber, 3.2 parts of side hydrogenated silicone oil with a hydrogen content of 0.58%, and 0.02 parts of 3-glycidylpropyl trimethoxysilane were added into a planetary mixer and mixed and stirred at -0.1 MPa for 2 hours; Mix evenly in the ratio of component A: group B by mass fraction = 1:1. After degassing in a degassing machine for 30 minutes, take 70g of the evenly mixed sample and put it into the mold. Vulcanize it at 100°C for 10 minutes to obtain transparent silicone rubber. The product was tested for performance. After mixing, the sample had a viscosity of 332451mpa·s, a transmittance of 90.4%, a haze of 8.1%, a refractive index of 1.49, a hardness of 53, a tensile strength of 6.21Mpa, a tear strength of 21.24KN\m, and an elongation at break of 424%. The base rubber was translucent and not yellow.

[0048] Comparative Example 3: A high refractive index and low haze addition type liquid silicone rubber and a preparation method thereof, wherein the specific preparation steps are as follows: Preparation of modified silica base rubber: Take 30 parts of vinyl-terminated long-chain polysiloxane (terminated vinyl polysiloxane) with a viscosity of 10000mPa·s, 15 parts of hydrophobic silica with a specific surface area of ​​300m2 / g, silica surface treatment agent (1.7 parts of methyl diphenyl ethoxy silane, 2.1 parts of 300 viscosity single-end hydroxy silicone oil, 0.3 parts of vinyl dimethyl ethoxy silane), 1.2 parts of deionized water, knead in a kneader for 1 hour until the material is evenly dispersed, turn on the heating, mix for 1 hour when the material temperature reaches 120°C, then vacuum treat for 1 hour, end the vacuum and turn off the heating to obtain the base rubber.

[0049] Preparation of component A: Add 20 parts of base rubber, 0.007 parts of 20000PPM Custer catalyst, 1 part of polyvinyl silicone oil with a vinyl content of 1.22%, and 2 parts of isopropanol into a planetary mixer and mix and stir for 2 hours at -0.1MPa; Preparation of component B: 20 ​​parts of base rubber, 3.2 parts of side hydrogenated silicone oil with a hydrogen content of 0.58%, and 0.02 parts of 3-glycidylpropyl trimethoxysilane were added into a planetary mixer and mixed and stirred at -0.1 MPa for 2 hours; Mix evenly in the ratio of component A: group B by mass fraction = 1:1. After degassing in a degassing machine for 30 minutes, take 70g of the evenly mixed sample and put it into the mold. Vulcanize it at 100°C for 10 minutes to obtain transparent silicone rubber. The product was tested for performance. After mixing, the sample had a viscosity of 287924mpa·s, a transmittance of 94.5%, a haze of 4.97%, a refractive index of 1.49, a hardness of 52, a tensile strength of 7.79Mpa, a tear strength of 30.45KN\m, and an elongation at break of 417%. The base rubber was translucent and not yellow.

[0050] Comparative Example 4: A high refractive index and low haze addition type liquid silicone rubber and a preparation method thereof, wherein the specific preparation steps are as follows: Preparation of modified silica base rubber: 15 parts of vinyl-terminated long-chain polysiloxane with a viscosity of 10000 mPa·s (terminated vinyl polysiloxane), 15 parts of vinylphenyl polysiloxane with a viscosity of 1000 mPa·s (phenyl content of 45 wt%, vinyl content of 0.65 wt%), 14.5 parts of polysiloxane with a specific surface area of ​​300 m 2 / g of hydrophobic silica and 1.2 parts of deionized water are kneaded in a kneader for 1 hour until the materials are evenly dispersed, and the heating is turned on. When the material temperature reaches 120°C, it is mixed for 1 hour, and then vacuum treated for 1 hour. After the vacuum is ended, the heating is turned off to obtain a base rubber.

[0051] Preparation of component A: Add 20 parts of base rubber, 0.007 parts of 20000PPM Custer catalyst, 1 part of polyvinyl silicone oil with a vinyl content of 1.22%, and 2 parts of isopropanol into a planetary mixer and mix and stir for 2 hours at -0.1MPa; Preparation of component B: 20 ​​parts of base rubber, 3.2 parts of side hydrogenated silicone oil with a hydrogen content of 0.58%, and 0.02 parts of 3-glycidylpropyl trimethoxysilane were added into a planetary mixer and mixed and stirred at -0.1 MPa for 2 hours; Mix evenly in the ratio of component A: group B by mass fraction = 1:1. After degassing in a degassing machine for 30 minutes, take 70g of the evenly mixed sample and put it into the mold. Vulcanize it at 100°C for 10 minutes to obtain transparent silicone rubber. The product was tested for performance. After mixing, the sample had a viscosity of 352487mpa·s, a transmittance of 91.95%, a haze of 8.85%, a refractive index of 1.50, a hardness of 49, a tensile strength of 5.48Mpa, a tear strength of 19.57KN\m, and an elongation at break of 417%. The base rubber was translucent and not yellow.

[0052] Comparative Example 1 shows that without using any white carbon black surface treatment agent, the rubber has a low refractive index and moderate transmittance and haze properties.

[0053] Comparative Example 2 and Comparative Example 1 show that the addition of white carbon black surface treatment agent (1.7 parts of methyl diphenyl ethoxy silane) significantly improves the refractive index of the rubber, but reduces the transmittance and haze performance.

[0054] Comparative Example 3 and Comparative Example 2 show that adding 2.1 parts of 300 viscosity single-end hydroxy silicone oil and 0.3 parts of vinyl dimethyl ethoxy silane as a white carbon surface treatment agent to Comparative Example 2 has little effect on the refractive index of the material, but improves the transmittance and haze performance.

[0055] Comparative Example 4 and Comparative Example 1 show that when 15 parts of the vinyl-terminated long-chain polysiloxane in Comparative Example 1 is replaced with vinylphenyl polysiloxane with a viscosity of 1000 mPa·s, the refractive index of the rubber is significantly improved, but the transmittance and haze performance are reduced.

[0056] Example 1 and Comparative Examples 2 and 4 show that the refractive indices of Comparative Examples 2 and 4 are similar. By replacing 15 parts of the vinyl-terminated long-chain polysiloxane in Comparative Example 2 with vinylphenyl polysiloxane with a viscosity of 1000 mPa·s, the refractive index of the rubber remains basically unchanged, but the haze is significantly reduced, indicating that when the refractive index of silicone oil is similar to that of white carbon black, the scattering inside the material will be significantly reduced.

[0057] Further, Example 2 and Example 1 show that by adding 2.1 parts of 300 viscosity single-end hydroxyl silicone oil silica surface treatment agent on the basis of Example 1, the refractive index of the rubber remains basically unchanged, but the haze is reduced and the transmittance is increased, indicating that the compatibility between silicone oil and hydrophobic silica can be improved by introducing a longer polysiloxane chain on the surface of hydrophobic silica.

[0058] It is further shown through Examples 3 and 2 that by adding 0.3 parts of vinyldimethylethoxysilane as a white carbon black surface treatment agent to Example 1, the refractive index of the rubber remains basically unchanged, but the haze and transmittance performance are further improved, indicating that by introducing vinyl groups onto the surface of hydrophobic white carbon black, the chemical bond between silicone oil and hydrophobic white carbon black can be enhanced, thereby reducing the haze.

[0059] Further, on the basis of Example 3, Example 4 further improves the refractive index of the material by increasing 0.3 parts of 1000 mPa·s vinylphenyl polysiloxane and adding 0.2 parts of 1,3-biphenyl tetramethyl disilazane, and the transmittance and haze remain basically unchanged. Example 5 further improves the refractive index and compatibility of white carbon black and silicone oil by increasing 0.38 parts of 1000 mPa·s vinylphenyl polysiloxane and 0.25 parts of ethoxytriphenylsilane, and additionally adding 0.5 parts of 300 viscosity single-end hydroxy silicone oil, and obtains a material with higher transmittance and refractive index and lower haze.

Claims

1. A high refractive index and low haze addition type liquid silicone rubber, characterized in that: The addition type liquid silicone rubber consists of component A and component B: component A consists of base rubber, catalyst, polyvinyl silicone oil and inhibitor; component B consists of base rubber, crosslinking agent, inhibitor and tackifier.

2. The high refractive index and low haze addition type liquid silicone rubber according to claim 1, characterized in that: The base rubber comprises white carbon black, a white carbon black surface treatment agent, vinyl silicone oil and water; wherein the white carbon black is a hydrophobic white carbon black; and the vinyl silicone oil is at least one of vinyl-terminated polysiloxane and vinyl-terminated phenyl polysiloxane.

3. The high refractive index and low haze addition type liquid silicone rubber according to claim 2, characterized in that: The hydrophobic silica is activated by a silica surface treatment agent, wherein the silica surface treatment agent is selected from at least one of 1,3-biphenyltetramethyldisilazane, ethoxytriphenylsilane, methoxytriphenylsilane, methyldiphenylethoxysilane, methyldiphenylmethoxysilane, ethoxydimethyl (phenyl) silane, methoxydimethyl (phenyl) silane, and mono-terminated hydroxyl silicone oil.

4. The high refractive index and low haze addition type liquid silicone rubber according to claim 3, characterized in that: The surface treatment method of hydrophobic silica is as follows: the hydrophobic silica needs to be treated during the preparation of the base rubber. According to the formula, the hydrophobic silica, silica surface treatment agent, vinyl silicone oil and deionized water are added into the kneader in sequence, stirred at room temperature for 1 to 3 hours, then heated at 70 to 200°C for 1 to 5 hours, and then vacuum treated at -0.1 MPa for 1 hour to obtain the base rubber.

5. The high refractive index and low haze addition type liquid silicone rubber according to claim 1, characterized in that: The catalyst is 100-20000ppm of Custer catalyst.

6. The high refractive index and low haze addition type liquid silicone rubber according to claim 1, characterized in that: The polyvinyl silicone oil is a polyvinyl silicone oil with a vinyl content of 0.2 to 1.5%; The crosslinking agent is at least one of a side hydrogen-containing polysiloxane and a terminal hydrogen-containing polysiloxane; The inhibitor is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol or tert-butanol; The tackifier is at least one of 3-glycidylpropyltrimethoxysilane, methyl trimethoxyacetate, ethyl triethoxyacetate, triethoxysilane, and trimethoxysilane.

7. A method for preparing a high refractive index and low haze addition type liquid silicone rubber, characterized in that: The method comprises the addition type liquid silicone rubber with high refractive index and low haze according to any one of claims 1 to 6, and the steps are as follows: S1. Prepare component A: mix the base rubber, catalyst, polyvinyl silicone oil and inhibitor evenly according to the proportion; S2. Prepare component B: mix the base rubber, cross-linking agent and tackifier evenly according to the proportion; S3. Components A and B obtained in step S2 and step S3 are fully mixed and degassed in a vacuum degassing machine for 20 to 50 minutes, and then vulcanized at 80 to 120° C. for 10 minutes.

8. The method for preparing addition type liquid silicone rubber according to claim 7, characterized in that: The A and B components are mixed and cooled while being stirred to keep the temperature below 40°C.