Low-hardness oil-leakage-free addition type liquid silicone rubber as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of silicone rubber, and particularly relates to low-hardness oil-leakage-free addition type liquid silicone rubber as well as a preparation method and application thereof. According to the low-hardness oil-leakage-free addition type liquid silicone rubber provided by the invention, polydimethylsiloxane with double-end methyl side chain vinyl is introduced into a formula to replace part of alpha, omega-vinyl polydimethylsiloxane, and a vinyl active group of the polydimethylsiloxane with the double-end methyl side chain vinyl is positioned on a side chain; vinyl active groups are adjusted to side chains from the molecular chain tail ends of siloxane chains, the vinyl active groups are surrounded by the surrounding siloxane chains, the steric hindrance is large, only a small amount of vinyl active groups can be smoothly subjected to hydrosilylation reaction, and the hydrosilylation effect is good. The prepared addition type liquid silicone rubber has dual properties of low hardness and no oil leakage, so that the technical problem that the existing low-hardness addition type liquid silicone rubber is easy to leak oil is solved.

Description

Technical Field

[0001] The present application belongs to the field of silicone rubber technology, and in particular relates to a low-hardness, oil-free addition-type liquid silicone rubber, a preparation method, and an application thereof. Background Art

[0002] Compared with condensation-type liquid silicone rubber, addition-type liquid silicone rubber usually uses a catalyst to catalyze the reaction of a vinyl-containing base polymer and a cross-linker containing Si-H bonds. After the catalytic reaction, it can achieve higher tensile strength and tear strength. At the same time, no small molecule by-products are produced, the safety is better, and it is easier to meet food grade and medical grade requirements. For example, addition-type liquid silicone rubber is used to prepare adult products, silicone dolls, baby toys, human masks, food molds, human prostheses, movie makeup special effects products and other products.

[0003] Adult products, silicone dolls, baby toys, human masks, food molds, human prostheses, movie makeup and special effects products, and other products have requirements for the hardness of liquid silicone rubber. Currently, low-hardness addition-type liquid silicone rubber is used as the raw material. However, the existing preparation process of low-hardness addition-type liquid silicone rubber usually fills a large amount of non-reactive polydimethylsiloxane to reduce the hardness, thereby preparing low-hardness addition-type liquid silicone rubber. The low-hardness addition-type liquid silicone rubber made in this way is filled with a large amount of non-reactive polydimethylsiloxane. When the product is stored for a long time, the product surface is prone to oil, which makes it difficult to meet market demand. Summary of the Invention

[0004] In view of this, the present application provides a low-hardness, oil-free addition-type liquid silicone rubber and its preparation method and application, which are used to solve the technical problem that the existing low-hardness addition-type liquid silicone rubber is prone to oil leakage.

[0005] In a first aspect, the present application provides a low-hardness, oil-free, addition-type liquid silicone rubber, comprising component A glue and component B glue;

[0006] Component A glue includes: base rubber and hydrosilylation reaction catalyst;

[0007] Component B adhesive includes: base adhesive, hydrogen-containing polydimethylsiloxane and hydrosilylation reaction inhibitor;

[0008] The basic rubber material comprises: α,ω-vinyl polydimethylsiloxane and polydimethylsiloxane with double-terminal methyl side chain vinyl.

[0009] Preferably, the molar fraction of vinyl groups in the dual-terminal methyl side chain vinyl group polydimethylsiloxane is 0.1% to 0.5%.

[0010] More preferably, the molar fraction of vinyl groups in the dual-terminal methyl side chain vinyl polydimethylsiloxane is 0.2% to 0.4%.

[0011] Preferably, the mass fraction of hydrogen in the hydrogen-containing polydimethylsiloxane is 0.05% to 0.3%.

[0012] More preferably, the mass fraction of hydrogen in the hydrogen-containing polydimethylsiloxane is 0.1% to 0.2%.

[0013] Preferably, the base rubber material further comprises: an oleophilic treatment agent and an inorganic filler.

[0014] Preferably, the base rubber material comprises, in parts by mass, 40 to 100 parts by mass of α,ω-vinyl polydimethylsiloxane, 80 to 160 parts by mass of polydimethylsiloxane with double-terminal methyl side chain vinyl groups, 10 to 25 parts by mass of a lipophilic treatment agent, and 60 to 120 parts by mass of an inorganic filler.

[0015] Preferably, the A-component adhesive comprises, by weight, 80 to 120 parts by weight of a base adhesive and 0.1 to 1 part by weight of a hydrosilylation reaction catalyst;

[0016] The B component glue comprises: 80-120 parts by mass of a base rubber material, 10-30 parts by mass of hydrogen-containing polydimethylsiloxane and 0.01-0.2 parts by mass of a hydrosilylation reaction inhibitor.

[0017] Preferably, the mass ratio of the component A glue to the component B glue is 1~1.2:1~1.2.

[0018] Preferably, the lipophilic treatment agent in the base rubber is at least one selected from hexamethyldisilazane, KH550 silane coupling agent, KH560 silane coupling agent, and KH570 silane coupling agent;

[0019] The inorganic filler is selected from at least one of white carbon black, calcium carbonate, quartz powder and titanium dioxide.

[0020] Preferably, the hydrosilylation reaction catalyst in the A-component glue is selected from platinum complexes or compounds.

[0021] The hydrosilylation reaction inhibitor in the B component glue is selected from one of maleate inhibitors, acetylene alcohol inhibitors, and vinyl ring inhibitors.

[0022] Preferably, the hydrosilylation reaction catalyst is selected from at least one of tetramethyldisiloxane chloroplatinic acid complex, chloroplatinic acid hydrate, platinum acetylacetonate supported on silicone oil, and (trimethyl)methylcyclopentadiene platinum supported on silicone oil;

[0023] The hydrosilylation reaction inhibitor is selected from at least one of dimethyl maleate, diallyl maleate, fumarates, methyl butynol, acetylene cyclohexanol, 3,5-dimethyl-1-hexyn-3-ol, 3,7,11-trimethyldodecyn-3-ol, 3-methyl-1-butynol and tetramethyltetravinylcyclotetrasiloxane complex.

[0024] A second aspect of the present application provides a method for preparing a low-hardness, oil-free addition-type liquid silicone rubber, which can be used to prepare the low-hardness, oil-free addition-type liquid silicone rubber described in the first aspect. The preparation method comprises the following steps:

[0025] The steps of preparing a base rubber material include kneading α,ω-vinyl polydimethylsiloxane, polydimethylsiloxane with double-terminal methyl side chain vinyl, a lipophilic treatment agent, an inorganic filler, and distilled water in sequence, heating and refluxing the mixture, performing a vacuum heat treatment, and grinding the mixture after cooling to obtain the base rubber material;

[0026] The step of preparing the A-component adhesive is to uniformly mix the base adhesive and the hydrosilylation reaction catalyst and degas to obtain the A-component adhesive;

[0027] The steps of preparing the B component glue are as follows: mixing the basic glue material, hydrogen-containing polydimethylsiloxane and the hydrosilylation reaction inhibitor uniformly and degassing to obtain the B component glue.

[0028] Preferably, in the step of preparing the base rubber material, kneading is specifically kneading in a kneader for 1 to 3 hours;

[0029] The heating reflux heat treatment is specifically heating to 110-130° C. and reflux heat treatment for 2-5 hours;

[0030] The vacuum heat treatment specifically comprises heating to 150-190° C. and vacuuming at -0.09 to -0.1 MPa for 2-5 hours.

[0031] The third aspect of the present application provides the use of the low-hardness, oil-free addition-type liquid silicone rubber described in the first aspect in the preparation of adult products, silicone dolls, baby toys, human masks, food molds, human prostheses, and movie makeup special effects products.

[0032] Compared with the prior art, the low-hardness, oil-free, addition-type liquid silicone rubber provided by this application has at least the following beneficial effects:

[0033] 1. The base rubber material of the low-hardness and oil-free addition-type liquid silicone rubber provided by the present application includes α,ω-vinyl polydimethylsiloxane and polydimethylsiloxane with double-terminal methyl side chains and vinyl groups. Both are reactive polydimethylsiloxanes. However, since the active groups in the polydimethylsiloxane with double-terminal methyl side chains are located in the side chains, the active groups are surrounded by the surrounding siloxane chains and have large steric hindrance. Only a small amount of vinyl active groups can smoothly undergo the hydrosilylation reaction. This makes the addition-type liquid silicone rubber provided by the present application not only meet the requirements of low hardness, but also not prone to oil bleeding.

[0034] 2. In the low-hardness, oil-free addition-type liquid silicone rubber provided in the present application, in addition to introducing polydimethylsiloxane with double-terminal methyl side chain vinyl groups during the preparation of the base rubber material, a lipophilic treatment agent is also used to treat silica. This allows the polydimethylsiloxane with double-terminal methyl side chain vinyl groups and silica to be mixed more thoroughly, so that it will not come out of the system, thereby reducing the oil bleeding phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] Figure 1 This is a schematic flow chart of a method for preparing a low-hardness, oil-free, addition-type liquid silicone rubber provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] The present application provides a low-hardness, oil-free addition-type liquid silicone rubber, a preparation method, and an application thereof, which are used to solve the technical problem that the existing low-hardness addition-type liquid silicone rubber is prone to oil leakage.

[0038] The following will clearly and completely describe the technical solution of this application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0039] At present, in the process of preparing low-hardness addition-type liquid silicone rubber, a large amount of non-reactive polydimethylsiloxane is used to reduce the hardness, which leads to poor storage performance of low-hardness addition-type liquid silicone rubber, and it is easy to leak oil after being stored for a certain period of time; in view of this, the present application provides a low-hardness and oil-free addition-type liquid silicone rubber, whose formula composition includes component A glue and component B glue, component A glue includes: base glue and silicon hydrogen addition reaction catalyst, component B glue includes: base glue, hydrogen-containing polydimethylsiloxane and silicon hydrogen addition reaction inhibitor, the base glue includes: α, ω-vinyl polydimethylsiloxane and polydimethylsiloxane with double-terminal methyl side chain vinyl; the α, ω-vinyl polydimethylsiloxane and double-terminal methyl side chain vinyl in the base glue Chain vinyl polydimethylsiloxane can undergo silanol hydroaddition reaction with hydrogen-containing polydimethylsiloxane to form addition-type liquid silicone rubber, but the vinyl group in α,ω-vinyl polydimethylsiloxane is located at the end group and is an end group active group, while the end group of polydimethylsiloxane with double-terminal methyl side chain vinyl is methyl, there is no active group, and the vinyl active group is located in the side chain; the terminal vinyl active group is at the end of the siloxane chain, with less steric hindrance and easier to move and orient. The terminal vinyl group in α,ω-vinyl polydimethylsiloxane easily undergoes silanol hydroaddition reaction with hydrogen-containing polydimethylsiloxane, while the side chain vinyl active group is surrounded by the surrounding siloxane chains, the vinyl is confined to the interior of the molecular structure, the activity is restricted, and the reaction site is not easy to contact Si-H bond, and it is difficult to undergo silanol addition reaction with hydrogen-containing polydimethylsiloxane. Only a small amount of vinyl active groups in polydimethylsiloxane with double-terminal methyl side chain vinyl can smoothly undergo silanol addition reaction and be connected to the three-dimensional cross-linked network of addition-type liquid silicone rubber; the low-hardness addition-type liquid silicone rubber provided by the present application introduces a specific polydimethylsiloxane with double-terminal methyl side chain vinyl in the formula, replaces part of the α, ω-vinyl polydimethylsiloxane, adjusts the vinyl active group from the molecular chain end of the siloxane chain to the side chain, reduces the silanol addition reaction of the vinyl active group and the Si-H bond, reduces the cross-linking degree of the addition-type liquid silicone rubber, and is a low-hardness liquid silicone rubber. At the same time, it can also be connected to the three-dimensional cross-linked network of the addition-type liquid silicone rubber and is not easy to oil. Therefore, the present application provides a low-hardness addition-type liquid silicone rubber with good storage performance and no oiling after storage for 7 days, 15 days, or even one month.

[0040] Preferably, in the low-hardness addition-type liquid silicone rubber provided by the present application, the polydimethylsiloxane with double-terminal methyl side chain vinyl groups introduced has a vinyl mole fraction of 0.1% to 0.5%; more preferably, the mole fraction is 0.2% to 0.4%; and the viscosity is about 50 mPa.s to 1000 mPa.s.

[0041] Preferably, in the low-hardness addition-type liquid silicone rubber provided in the present application, the amounts of α,ω-vinyl polydimethylsiloxane and polydimethylsiloxane with double-terminal methyl side chains are also controlled, and the mass ratio of α,ω-vinyl polydimethylsiloxane to polydimethylsiloxane with double-terminal methyl side chains is approximately 40~100:80~160.

[0042] Preferably, in the low-hardness addition-type liquid silicone rubber provided in the present application, a lipophilic treatment agent and an inorganic filler are also introduced into the base rubber material. The inorganic filler is usually white carbon black, etc., which can be used to regulate the strength of the addition-type liquid silicone rubber, and the lipophilic treatment agent is usually hexamethyldisilazane and a silane coupling agent, the purpose of which is to perform lipophilic treatment on inorganic fillers such as white carbon black, which allows organic components such as polydimethylsiloxane with double-terminal methyl side chain vinyl to mix more thoroughly with inorganic fillers such as white carbon, so that they will not emerge from the system, thereby reducing the occurrence of oil bleeding.

[0043] The low-hardness, oil-free, addition-type liquid silicone rubber provided by the present application will be specifically described below with reference to embodiments and experimental examples.

[0044] Example 1

[0045] Example 1 of the present application provides a method for preparing low-hardness, oil-free, addition-type liquid silicone rubber. The preparation method includes: a step of preparing a base rubber material, a step of preparing component A rubber, and a step of preparing component B rubber.

[0046] The steps of preparing the basic rubber compound include: adding 80g of precipitated silica, 40g of 1000mPa.s α,ω-vinyl polydimethylsiloxane, 160g of 200mPa.s polydimethylsiloxane with very few vinyl groups in the double-end methyl side chain (vinyl mole fraction 0.3%, Jiangxi Andeli High-tech Technology Co., Ltd., brand: ADL-V02MA), 20g of lipophilic treatment agent hexamethyldisilazane, and 4g of distilled water into a kneader and cold-kneading for 2h, then heating to 110-130°C and reflux heat treatment for 3h, then heating to 150-190°C, vacuuming at -0.09 to -0.1Mpa for 4h, cooling and grinding to obtain the basic rubber compound.

[0047] The steps of preparing component A glue include: mixing 100g of base glue and 0.23g of tetramethyldisiloxane chloroplatinic acid complex with a platinum metal content of 5000ppm as a hydrosilylation reaction catalyst, and degassing to prepare component A glue.

[0048] The steps of preparing component B glue include: adding 16 g of hydrogenated polydimethylsiloxane (hydrogen content 0.1% by mass), 0.02 g of 3-methyl-1-butynol and tetramethyltetravinylcyclotetrasiloxane complex inhibitor as a hydrosilylation reaction inhibitor to 100 g of base glue, mixing evenly and degassing to prepare component B glue.

[0049] The combination of component A and component B is a two-component, low-hardness, oil-free, addition-type liquid silicone rubber.

[0050] Example 2

[0051] Example 2 of the present application provides a method for preparing low-hardness, oil-free, addition-type liquid silicone rubber. The difference from Example 1 is that the amount of raw materials is adjusted. The preparation method includes: the steps of preparing a base rubber material, preparing component A rubber, and preparing component B rubber.

[0052] The steps of preparing the basic rubber compound include: adding 80g of precipitated silica, 60g of 1000mPa.s α,ω-vinyl polydimethylsiloxane, 140g of 200mPa.s polydimethylsiloxane with very few vinyl groups in the double-end methyl side chain (vinyl mole fraction 0.3%, Jiangxi Andeli High-tech Technology Co., Ltd., brand: ADL-V02MA), 20g of lipophilic treatment agent hexamethyldisilazane, and 4g of distilled water into a kneader and cold-kneading for 2h, then heating to 110-130°C and reflux heat treatment for 3h, then heating to 150-190°C, vacuuming at -0.09 to -0.1Mpa for 4h, cooling and grinding to obtain the basic rubber compound.

[0053] The steps of preparing component A glue include: mixing 100g of base glue and 0.23g of tetramethyldisiloxane chloroplatinic acid complex with a platinum metal content of 5000ppm as a hydrosilylation reaction catalyst, and degassing to prepare component A glue.

[0054] The steps of preparing component B glue include: mixing 100g of base glue, 20g of hydrogenated polydimethylsiloxane (hydrogen content 0.1% by mass), 0.025g of 3-methyl-1-butynol and tetramethyltetravinylcyclotetrasiloxane complex inhibitor as a hydrosilylation reaction inhibitor, and degassing to prepare component B glue.

[0055] The combination of component A and component B is a two-component, low-hardness, oil-free, addition-type liquid silicone rubber.

[0056] Example 3

[0057] Example 3 of the present application provides a method for preparing low-hardness, oil-free, addition-type liquid silicone rubber. The difference from Example 1 is that the amount of raw materials is adjusted. The preparation method includes: the steps of preparing a base rubber material, preparing component A rubber, and preparing component B rubber.

[0058] The steps of preparing the basic rubber compound include: adding 80g of precipitated silica, 60g of 500mpa.s α,ω-vinyl polydimethylsiloxane, 140g of 200mpa.s polydimethylsiloxane with very few vinyl groups in the double-end methyl side chain (vinyl mole fraction 0.3%, Jiangxi Andeli High-tech Technology Co., Ltd., brand: ADL-V02MA), 20g of lipophilic treatment agent hexamethyldisilazane, and 4g of distilled water into a kneader and cold-kneading for 2h, then heating to 110-130°C and reflux heat treatment for 3h, then heating to 150-190°C, vacuuming at -0.09 to -0.1Mpa for 4h, cooling and grinding to obtain the basic rubber compound.

[0059] The steps of preparing component A glue include: mixing 100g of base glue and 0.23g of tetramethyldisiloxane chloroplatinic acid complex with a platinum metal content of 5000ppm as a hydrosilylation reaction catalyst, and degassing to prepare component A glue.

[0060] The steps of preparing component B glue include: mixing 100g of base glue, 22g of hydrogenated polydimethylsiloxane (hydrogen content 0.1% by mass), 0.025g of 3-methyl-1-butynol and tetramethyltetravinylcyclotetrasiloxane complex inhibitor as a hydrosilylation reaction inhibitor, and degassing to prepare component B glue.

[0061] The combination of component A and component B is a two-component, low-hardness, oil-free, addition-type liquid silicone rubber.

[0062] Example 4

[0063] Example 4 of the present application provides a method for preparing low-hardness, oil-free, addition-type liquid silicone rubber. The difference from Example 1 is that the amount of raw materials is adjusted. The preparation method includes: the steps of preparing a base rubber material, preparing component A rubber, and preparing component B rubber.

[0064] The steps of preparing the basic rubber compound include: adding 80g of precipitated silica, 40g of 1000mPa.s α,ω-vinyl polydimethylsiloxane, 160g of 200mPa.s polydimethylsiloxane with very few vinyl groups in the double-end methyl side chain (vinyl mole fraction 0.2%, Jiangxi Andeli High-tech Technology Co., Ltd., brand: ADL-V02MA), 20g of lipophilic treatment agent hexamethyldisilazane, and 4g of distilled water into a kneader and cold-kneading for 2h, then heating to 110-130°C and reflux heat treatment for 3h, then heating to 150-190°C, vacuuming at -0.09 to -0.1Mpa for 4h, cooling and grinding to obtain the basic rubber compound.

[0065] The steps of preparing component A glue include: mixing 100g of base glue and 0.23g of tetramethyldisiloxane chloroplatinic acid complex with a platinum metal content of 5000ppm as a hydrosilylation reaction catalyst, and degassing to prepare component A glue.

[0066] The steps of preparing component B glue include: mixing 100g of base glue, 16g of hydrogenated polydimethylsiloxane (hydrogen content 0.1% by mass), 0.025g of 3-methyl-1-butynol and tetramethyltetravinylcyclotetrasiloxane complex inhibitor as a hydrosilylation reaction inhibitor, and degassing to prepare component B glue.

[0067] The combination of component A and component B is a two-component, low-hardness, oil-free, addition-type liquid silicone rubber.

[0068] Example 5

[0069] Example 5 of the present application provides a method for preparing low-hardness addition-type liquid silicone rubber. As a first comparison of Examples 1-4, the preparation method includes: a step of preparing a base rubber material, a step of preparing component A rubber, and a step of preparing component B rubber.

[0070] The steps of preparing the basic rubber compound include: adding 80g of precipitated silica, 60g of 1000mpa.s α,ω-vinyl polydimethylsiloxane, 140g of 200mpa.s polydimethylsiloxane (dimethyl silicone oil, non-reactive type), 20g of lipophilic treatment agent hexamethyldisilazane, and 4g of distilled water into a kneader and cold-kneading for 2h, then heating to 110-130°C and reflux heat treatment for 3h, then heating to 150-190°C, vacuuming at -0.09 to -0.1Mpa for 4h, cooling and grinding to obtain the basic rubber compound.

[0071] The steps of preparing component A glue include: mixing 100g of base glue and 0.23g of tetramethyldisiloxane chloroplatinic acid complex with a platinum metal content of 5000ppm as a hydrosilylation reaction catalyst, and degassing to prepare component A glue.

[0072] The steps of preparing component B glue include: mixing 100g of base glue, 15g of hydrogenated polydimethylsiloxane (hydrogen content 0.1% by mass), 0.02g of 3-methyl-1-butynol and tetramethyltetravinylcyclotetrasiloxane complex inhibitor as a hydrosilylation reaction inhibitor, and degassing to prepare component B glue.

[0073] The combination of component A and component B is a two-component low-hardness addition-type liquid silicone rubber.

[0074] Example 6

[0075] Example 6 of the present application provides a method for preparing low-hardness addition-type liquid silicone rubber. As a second comparison to Examples 1-4, the preparation method includes: a step of preparing a base rubber material, a step of preparing component A rubber, and a step of preparing component B rubber.

[0076] The steps of preparing the basic rubber material include: adding 80g of precipitated silica, 60g of 1000mpa.s α,ω-vinyl polydimethylsiloxane, 20g of lipophilic treatment agent hexamethyldisilazane, and 4g of distilled water into a kneader and cold-kneading for 2h, then heating to 110-130°C and reflux heat treatment for 3h, then heating to 150-190°C, vacuuming at -0.09 to -0.1Mpa for 4h, cooling and grinding to obtain the basic rubber material.

[0077] The steps for preparing component A glue include: mixing 100g of base glue, 50g of polydimethylsiloxane (vinyl molar fraction 0.3%) with very little vinyl in the double-terminal methyl side chain, and 0.23g of tetramethyldisiloxane chloroplatinic acid complex with a platinum metal content of 5000ppm as a hydrosilylation reaction catalyst, and degassing to prepare component A glue.

[0078] The steps of preparing component B glue include: mixing 100g of basic glue, 15g of hydrogen-containing polydimethylsiloxane (hydrogen content 0.1% by mass), 50g of polydimethylsiloxane with very few vinyl groups in double-terminal methyl side chains (vinyl molar fraction 0.3%), 0.02g of 3-methyl-1-butynol and tetramethyltetravinylcyclotetrasiloxane complex inhibitor as a hydrosilylation reaction inhibitor, and degassing to prepare component B glue.

[0079] The combination of component A and component B is a two-component low-hardness addition-type liquid silicone rubber.

[0080] Example 7

[0081] Example 7 of the present application provides a method for preparing low-hardness, oil-free, addition-type liquid silicone rubber. As a third comparison of Examples 1-4, the preparation method includes: a step of preparing a base rubber material, a step of preparing component A rubber, and a step of preparing component B rubber.

[0082] The steps of preparing the basic rubber compound include: adding 80g of precipitated silica, 40g of 1000mpa.s α,ω-vinyl polydimethylsiloxane, 160g of 200mpa.s one-terminal methyl and one-terminal vinyl polydimethylsiloxane (vinyl mole fraction 0.3%), 20g of lipophilic treatment agent hexamethyldisilazane, and 4g of distilled water into a kneader and cold-kneading for 2h, then heating to 110-130°C and reflux heat treatment for 3h, then heating to 150-190°C, vacuuming at -0.09 to -0.1Mpa for 4h, cooling and grinding to obtain the basic rubber compound.

[0083] The steps of preparing component A glue include: mixing 100g of base glue and 0.23g of tetramethyldisiloxane chloroplatinic acid complex with a platinum metal content of 5000ppm as a hydrosilylation reaction catalyst, and degassing to prepare component A glue.

[0084] The steps of preparing component B glue include: adding 16 g of hydrogenated polydimethylsiloxane (hydrogen content 0.1% by mass), 0.02 g of 3-methyl-1-butynol and tetramethyltetravinylcyclotetrasiloxane complex inhibitor as a hydrosilylation reaction inhibitor to 100 g of base glue, mixing evenly and degassing to prepare component B glue.

[0085] The combination of component A and component B is a two-component low-hardness addition-type liquid silicone rubber.

[0086] Experimental Example 1

[0087] The present application conducts performance tests on the low-hardness, oil-free addition-type liquid silicone rubber provided in Examples 1-4 and the low-hardness, addition-type liquid silicone rubber provided in Examples 5-7.

[0088] The test process includes: first, the component A glue and the component B glue in the low-hardness, oil-free addition-type liquid silicone rubber provided in Example 1 are evenly mixed in a mass ratio of 1:1, poured into a cavity mold with a size of 150 mm × 150 mm × 6 mm, and then placed in a 100°C oven and baked for 15 minutes to obtain sample 1; according to the above method, the component A glue and the component B glue provided in Examples 2-7 are prepared into samples 2-7 in sequence; then, a hardness test and storage stability test are performed on samples 1-7 using a type A Shore hardness tester and oil-absorbing paper. The test results are shown in Table 1.

[0089] Table 1: Performance test results

[0090]

[0091] As can be seen from Table 1, the low-hardness addition-type liquid silicone rubber sample 5 provided in Example 5 has a relatively low hardness of only 1 degree. Oil stains appear on the surface of the oil-absorbing paper after seven days of storage, obvious oil stains appear after half a month, and substantial oil stains appear after one month. This indicates that the low-hardness addition-type liquid silicone rubber provided in Example 5, due to the addition of non-reactive polydimethylsiloxane in the formula, does not contain active vinyl groups and is unable to participate in the hydrosilylation reaction. This not only results in a low hardness of the addition-type liquid silicone rubber, but also causes oiling after 7 days of storage, more severe oiling after 15 days, and very severe oiling after 30 days. In contrast, the addition-type liquid silicone rubbers provided in Examples 1-4 and Example 6 have a relatively good hardness, not exceeding 5 shore A, and have good storage stability, with little oiling. Furthermore, the addition-type liquid silicone rubber provided in Example 7 has relatively good storage stability, with little oiling, but a relatively high hardness. This may be due to the high reactivity of the vinyl-terminated polydimethylsiloxane, which easily allows a large number of active vinyl groups to undergo hydrosilylation and be incorporated into the three-dimensional crosslinked network of the addition-type liquid silicone rubber, thereby increasing the crosslinking degree and hardness of the silicone rubber.

[0092] As can be further seen from Table 1, although the addition-type liquid silicone rubber provided in Example 6 did not cause oil stains on the surface of the oil-absorbing paper after being placed on the oil-absorbing paper for seven days, its long-term storage stability was not very good. The storage stability of the addition-type liquid silicone rubber provided in Example 6 was slightly lower than that of the addition-type liquid silicone rubber provided in Examples 1-4. This may be because the polydimethylsiloxane with dual-terminal methyl side chain vinyl groups was not pre-added to the base rubber material, resulting in a lack of thorough mixing with the silica.

[0093] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A low-hardness, oil-free addition-type liquid silicone rubber, characterized in that: Including A component glue and B component glue; Component A glue includes: base rubber and hydrosilylation reaction catalyst; Component B adhesive includes: base adhesive, hydrogen-containing polydimethylsiloxane and hydrosilylation reaction inhibitor; The basic rubber material comprises: α,ω-vinyl polydimethylsiloxane and polydimethylsiloxane with double-terminal methyl side chain vinyl.

2. The low-hardness, oil-free addition-type liquid silicone rubber according to claim 1, characterized in that: The molar fraction of vinyl groups in the double-terminal methyl side chain vinyl group polydimethylsiloxane is 0.1% to 0.5%.

3. The low-hardness, oil-free addition-type liquid silicone rubber according to claim 1, characterized in that: The hydrogen content of the hydrogen-containing polydimethylsiloxane is 0.05% to 0.3%.

4. The low-hardness, oil-free addition-type liquid silicone rubber according to claim 1, characterized in that: The basic rubber material also includes: an oleophilic treatment agent and an inorganic filler.

5. The low-hardness, oil-free addition-type liquid silicone rubber according to claim 4, characterized in that: Calculated in parts by mass, the base rubber material includes: 40 to 100 parts by mass of α,ω-vinyl polydimethylsiloxane, 80 to 160 parts by mass of polydimethylsiloxane with double-terminal methyl side chain vinyl groups, 10 to 25 parts by mass of a lipophilic treatment agent, and 60 to 120 parts by mass of an inorganic filler.

6. The low-hardness, oil-free addition-type liquid silicone rubber according to claim 1, characterized in that: Calculated by mass, the A component glue includes: 80-120 mass parts of base rubber and 0.1-1 mass parts of hydrosilylation reaction catalyst; The B component glue comprises: 80-120 parts by mass of a base rubber material, 10-30 parts by mass of hydrogen-containing polydimethylsiloxane and 0.01-0.2 parts by mass of a hydrosilylation reaction inhibitor.

7. The low-hardness, oil-free addition-type liquid silicone rubber according to claim 4, characterized in that: The lipophilic treatment agent in the base rubber is selected from at least one of hexamethyldisilazane, KH550 silane coupling agent, KH560 silane coupling agent, and KH570 silane coupling agent; The inorganic filler is selected from at least one of white carbon black, calcium carbonate, quartz powder and titanium dioxide.

8. The low-hardness, oil-free addition-type liquid silicone rubber according to claim 1, characterized in that: The hydrosilylation reaction catalyst in the A-component glue is selected from a platinum complex or compound; The hydrosilylation reaction inhibitor in the B component glue is selected from one of maleate inhibitors, acetylene alcohol inhibitors, and vinyl ring inhibitors.

9. The method for preparing a low-hardness, oil-free addition-type liquid silicone rubber according to any one of claims 1 to 8, characterized in that: The following steps are involved: The steps of preparing a base rubber material include kneading α,ω-vinyl polydimethylsiloxane, polydimethylsiloxane with double-terminal methyl side chain vinyl, a lipophilic treatment agent, an inorganic filler, and distilled water in sequence, heating and refluxing the mixture, performing a vacuum heat treatment, and grinding the mixture after cooling to obtain the base rubber material; The step of preparing the A-component adhesive is to uniformly mix the base adhesive and the hydrosilylation reaction catalyst and degas to obtain the A-component adhesive; The steps of preparing the B component glue are as follows: mixing the basic glue material, hydrogen-containing polydimethylsiloxane and the hydrosilylation reaction inhibitor uniformly and degassing to obtain the B component glue.

10. Use of the low-hardness, oil-free addition-type liquid silicone rubber according to any one of claims 1 to 8 in the preparation of adult products, silicone dolls, baby toys, human masks, food molds, human prostheses, or movie makeup special effects products.

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