A high-temperature resistant silicone rubber compound reinforced with rice husk ash-precipitated silica, its preparation method and application

Abstract

The present invention uses rice husk ash to precipitate silica to reinforce methyl vinyl silicone rubber raw rubber, and cooperates with other components to prepare a silicone rubber masterbatch. It has good strength characteristics of conventional silicone rubber and better temperature resistance characteristics than conventional ordinary silicone rubber. The application of rice husk precipitated silica in the preparation of silicone rubber masterbatch greatly improves the application expansion of rice husk precipitated silica in the civilian field and is conducive to resource recycling.

Description

Technical Field

[0001] The present invention belongs to the field of silicone rubber masterbatch, and particularly relates to a high-temperature resistant silicone rubber masterbatch reinforced by rice husk ash precipitated silica, a preparation method thereof and an application thereof. Background Art

[0002] At present, silicone rubber masterbatches at home and abroad generally use fumed silica (fumed white carbon black) or precipitated silica (precipitated white carbon black) prepared by the water glass method to reinforce raw rubber. Although the obtained silicone rubber masterbatch has high strength and good transparency, the preparation cost remains high, and the heat resistance is not high. Usually, materials such as transition metals are also needed to improve the heat resistance of the silicone rubber masterbatch. Summary of the Invention

[0003] The present invention provides a silicone rubber masterbatch, and its preparation raw materials include: methyl vinyl silicone rubber raw rubber, silica and a structure control agent, and at least rice husk ash precipitated silica is included in the silica.

[0004] According to an embodiment of the present invention, the preparation raw materials include: methyl vinyl silicone rubber raw rubber, silica accounting for 10-60% by weight of the raw rubber, a structure control agent accounting for 5-12% by weight of the silica, and at least rice husk ash precipitated silica is included in the silica.

[0005] According to an embodiment of the present invention, the silica accounts for 20-55% by weight of the raw rubber, such as 30-45%, and exemplary are 35%, 40%, 42%, 45%, etc.

[0006] According to an embodiment of the present invention, the structure control agent accounts for 6-11% by weight of the silica, such as 6-9%, and exemplary are 7%, 7.8%, 8%, etc.

[0007] According to an embodiment of the present invention, the methyl vinyl silicone rubber raw rubber is selected from at least one of methyl vinyl silicone rubber raw rubbers with a vinyl molar content in the range of 0.01-8%, such as selected from at least one of methyl vinyl silicone rubber raw rubbers with a vinyl molar content of 0.03%, 0.05%, 0.08%, 0.14%, 0.18%, 0.22%, 1.0%, 3.0%, 5.0%; exemplary selected from methyl vinyl silicone rubber raw rubber with a vinyl molar content of 0.05% and methyl vinyl silicone rubber raw rubber with a vinyl molar content of 0.22%, for example: a mixture of methyl vinyl silicone rubber raw rubber with a vinyl molar content of 0.03-0.08% and methyl vinyl silicone rubber raw rubber with a vinyl molar content of 0.15-0.30% with a mass ratio of (1-3):(2-4).

[0008] According to an embodiment of the present invention, the silica may be only rice husk ash precipitated silica, or a mixture of non-rice husk ash precipitated silica and rice husk ash precipitated silica. Further, the rice husk ash precipitated silica accounts for more than 0 to 100% by weight of the silica, such as 30%, 33.3%, 50%, 66%, 100%, and is preferably 5-70%.

[0009] The "rice husk ash precipitated silica" refers to silica prepared by a precipitation method using rice husk or rice husk ash as a raw material. According to the present invention, the particle size of the rice husk ash precipitated silica is preferably 1-50 nm, such as 2-15 nm; the BET specific surface area is preferably 10-200 m 2 / g, such as 20-70 m 2 / g; the pore volume is preferably 0.05-1 cm 2 / g, such as 0.1-0.5 cm 2 / g.

[0010] The "non-rice husk ash precipitated silica" refers to other silica except rice husk ash precipitated silica, such as fumed silica, calcined silica, direct precipitation silica, sol-gel silica, ultrasonic silica, etc.

[0011] The "fumed silica" refers to silica prepared by reacting silicon halide, oxygen (or air) and hydrogen at high temperature.

[0012] The "calcined silica" is silica prepared by mixing a mineral containing a silicon source with a reagent and then calcining.

[0013] The "direct precipitation silica" refers to silica prepared by a precipitation method using silicate and sulfuric acid (or hydrochloric acid or pure carbon dioxide) as raw materials.

[0014] The "sol-gel silica" refers to silica obtained by using a metal salt of silicon as a silicon source, hydrolyzing to form a silica gel, and drying after removing the organic solvent.

[0015] The "ultrasonic silica" is silica prepared by mixing a mineral containing a silicon source with a reagent and utilizing the chemical effect and mechanical effect generated during ultrasonic cavitation.

[0016] The rice husk ash precipitated silica and non-rice husk ash precipitated silica can be prepared by methods known in the art or purchased through commercial channels. For example, the rice husk ash precipitated silica can be purchased from Green Sugar AG.

[0017] According to an embodiment of the present invention, the rice husk ash precipitated silica may be selected from iron oxide-coated rice husk ash precipitated silica.

[0018] The structured control agent may be selected from the structured control agents known in the art, for example, hydroxy silicone oil, hexamethyldisilazane, methoxy silicone oil, dimethyldiethoxysilane, dimethyldimethoxysilane, etc. In one embodiment of the present invention, the structured control agent is hydroxy silicone oil. According to an embodiment of the present invention, the hydroxy silicone oil is medium-viscosity hydroxy silicone oil or low-viscosity hydroxy silicone oil. For example, the viscosity of the medium-viscosity hydroxy silicone oil is 46 - 100 mm / s 2 , and the viscosity of the low-viscosity hydroxy silicone oil is 25 - 45 mm / s 2 . Further, the hydroxy content in the hydroxy silicone oil is 4 - 9.5 wt%, exemplarily 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%.

[0019] According to an embodiment of the present invention, the preparation raw materials may further include a release agent, such as zinc stearate, etc.

[0020] According to an embodiment of the present invention, the preparation raw materials may further contain a heat-resistant agent, such as iron(III) oxide, etc.

[0021] According to an embodiment of the present invention, the preparation raw materials may further contain other additives, such as a flame retardant, etc. The flame retardant is, for example, aluminum hydroxide, etc.

[0022] According to an exemplary embodiment of the present invention, the preparation raw materials of the silicone rubber masterbatch include, by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 42 parts of rice husk ash precipitated silica, and 3.3 parts of low-viscosity hydroxy silicone oil;

[0023] The methyl vinyl silicone rubber raw rubber includes methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.05% and methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.22% in a mass ratio of 2:3;

[0024] The hydroxy content of the low-viscosity hydroxy silicone oil is 9 wt%.

[0025] According to an exemplary embodiment of the present invention, the preparation raw materials of the silicone rubber masterbatch include, by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 28 parts of rice husk ash precipitated silica, 14 parts of non-rice husk ash precipitation method silica, and 3.3 parts of low-viscosity hydroxy silicone oil;

[0026] The methyl vinyl silicone rubber raw rubber includes methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.05% and methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.22% in a mass ratio of 2:3;

[0027] The hydroxyl content of the low-viscosity hydroxyl silicone oil is 9 wt%.

[0028] According to an exemplary embodiment of the present invention, the raw materials for preparing the silicone rubber masterbatch include, by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 21 parts of rice husk ash-precipitated silica, 21 parts of non-rice husk ash-precipitated silica, and 3.3 parts of low-viscosity hydroxyl silicone oil;

[0029] The methyl vinyl silicone rubber raw rubber includes methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.05% and methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.22% in a mass ratio of 2:3;

[0030] The hydroxyl content of the low-viscosity hydroxyl silicone oil is 9 wt%.

[0031] According to an exemplary embodiment of the present invention, the raw materials for preparing the silicone rubber masterbatch include, by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 14 parts of rice husk ash-precipitated silica, 28 parts of non-rice husk ash-precipitated silica, and 3.3 parts of low-viscosity hydroxyl silicone oil;

[0032] The methyl vinyl silicone rubber raw rubber includes methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.05% and methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.22% in a mass ratio of 2:3;

[0033] The hydroxyl content of the low-viscosity hydroxyl silicone oil is 9 wt%.

[0034] The present invention also provides a method for preparing the above silicone rubber masterbatch, which includes the following steps: preparing the silicone rubber masterbatch from the above raw materials.

[0035] According to an embodiment of the present invention, the preparation method includes the following steps:

[0036] (1) Mixing methyl vinyl silicone rubber raw rubber and a structure control agent;

[0037] (2) Adding silica to the mixture obtained in step (1);

[0038] (3) Heating the mixture obtained in step (2).

[0039] According to the present invention, in step (1), under the protection of an inert gas, methyl vinyl silicone rubber raw rubber and a structure control agent are mixed, and the inert gas is, for example, nitrogen.

[0040] According to the present invention, in step (2), the silica is added in batches.

[0041] According to the present invention, in step (3), after the materials in step (2) are mixed evenly, the first temperature increase is carried out. After the temperature increase is completed, vacuum is pumped, then the second temperature increase is carried out and heat preservation is carried out, and then the vacuum is released, and the temperature is cooled down under the protection of inert gas.

[0042] Preferably, each raw material has the dosage as described above.

[0043] According to an embodiment of the present invention, in step (2), silicon dioxide can be added in at least 3 times, for example, 4 times, 5 times or 6 times. For example, with the increase in the number of times, the addition amount of silicon dioxide generally shows a decreasing trend; exemplarily, when added in 5 times, the addition is carried out in accordance with the proportions of 30%, 25%, 25%, 15%, and 5% of the total amount of silicon dioxide in sequence.

[0044] According to an embodiment of the present invention, in step (2), after each batch of silicon dioxide is added, it is necessary to mix it evenly with other materials before adding the next batch of silicon dioxide.

[0045] According to an embodiment of the present invention, in step (3), inert gas is passed throughout the first temperature increase process for protection.

[0046] According to an embodiment of the present invention, in step (3), the temperature reached during the first temperature increase is 110 - 130 °C, for example, 115 - 125 °C, and exemplarily 115 °C, 120 °C, 125 °C.

[0047] According to an embodiment of the present invention, in step (3), after the vacuum is pumped, the vacuum degree is -0.1 to -0.05 MPa, and exemplarily -0.09 MPa.

[0048] According to an embodiment of the present invention, in step (3), the temperature reached during the second temperature increase is 145 - 165 °C, for example, 150 - 160 °C, and exemplarily 150 °C, 155 °C, 160 °C.

[0049] According to an embodiment of the present invention, in step (3), the heat preservation time is 1 - 3 h, for example, 1.5 - 2.5 h, and exemplarily 1.5 h, 2 h, 2.5 h.

[0050] According to an embodiment of the present invention, in step (3), the temperature to which it is cooled down is below 100 °C, for example, below 80 °C.

[0051] According to an embodiment of the present invention, in step (3), after cooling down, it further includes the steps of discharging and filtering.

[0052] The present invention also provides a silicone rubber masterbatch prepared by the above method.

[0053] The present invention also provides the use of rice husk ash precipitated silica in the preparation of silicone rubber masterbatch.

[0054] Preferably, the rice husk ash precipitated silica is iron oxide-coated rice husk precipitated silica.

[0055] Wherein, the silicone rubber masterbatch has the meaning as described above.

[0056] The present invention also provides the use of the silicone rubber masterbatch in the preparation of silicone rubbers such as general-purpose silicone rubber, seals, wire and cable, nipples, insulating silicone rubber, high-temperature resistant silicone rubber, flame-retardant silicone rubber, rubber rollers, swimming caps, steam-resistant silicone rubber, conductive silicone rubber, automotive silicone rubber, etc., preferably in the preparation of high-temperature resistant seals.

[0057] Advantages of the present invention:

[0058] The present invention uses rice husk ash precipitated silica to reinforce the raw rubber of methyl vinyl silicone rubber, and cooperates with other components to prepare a silicone rubber masterbatch, which has good strength characteristics of conventional silicone rubber and better temperature resistance characteristics than conventional ordinary silicone rubber.

[0059] Moreover, the application of rice husk precipitated silica in the preparation of silicone rubber masterbatch greatly improves the application expansion of rice husk precipitated silica in the civil field, contributes to resource recycling and reduction of social waste. Especially when using iron oxide-coated rice husk precipitated silica to reinforce the raw rubber of methyl vinyl silicone rubber, no other heat-resistant agents need to be added, and the heat resistance of the prepared masterbatch product is better than that of conventional precipitated silica. Specific embodiments

[0060] The technical solutions of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to illustrate and explain the present invention exemplarily, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0061] Unless otherwise specified, the raw materials and reagents used in the following embodiments are all commercially available products or can be prepared by known methods.

[0062] Example 1

[0063] 40 parts of raw rubber of methyl vinyl silicone rubber with a vinyl molar fraction of 0.05% and 60 parts of raw rubber of methyl vinyl silicone rubber with a vinyl molar fraction of 0.22%, 3.3 parts of low-viscosity hydroxyl silicone oil with a hydroxyl content of 9 wt% (30 mm / s 2)Put it into a kneader and conduct nitrogen passivation treatment on the kneader. Add 42 parts of precipitated silica from rice husk ash (Green Sugar AG, particle size: 5 - 6 nm, BET specific surface area: 49.4 m 2 / g, purity: ≥98.5%, pore volume: 0.174 cm 2 / g) into the kneader in 5 portions, adding them in sequence according to the proportions of 30%, 25%, 25%, 15%, and 5% of the total amount of precipitated silica from rice husk ash respectively. After each addition, wait until the batch is mixed evenly before adding the next batch of precipitated silica from rice husk ash. After all the precipitated silica from rice husk ash is mixed evenly with the materials in the kneader, gradually raise the temperature, keep nitrogen flowing throughout the process for protection, raise the temperature to 120°C, turn off the nitrogen, start to pump vacuum, with a vacuum degree of -0.09 Mpa, gradually raise the temperature to 155°C, and maintain for 1.5 hours. Then release the vacuum and switch to nitrogen flow; Cool the obtained product to below 100°C, discharge, filter, and obtain the silicone rubber masterbatch.

[0064] Example 2

[0065] Put 40 parts of raw methyl vinyl silicone rubber with a vinyl molar fraction of 0.05% and 60 parts of raw methyl vinyl silicone rubber with a vinyl molar fraction of 0.22%, and 3.3 parts of low-viscosity hydroxyl silicone oil with a hydroxyl content of 9 wt% (30 mm / s 2 ) into a kneader and conduct nitrogen passivation treatment on the kneader. Mix 28 mass parts of precipitated silica from rice husk ash (Green Sugar AG, particle size: 5 - 6 nm, BET specific surface area: 49.4 m 2 / g, purity: ≥98.5%, pore volume: 0.174 cm 2 / g) and 14 parts of ordinary precipitated silica YX900A evenly. Add the mixed silica into the kneader in 5 portions, adding them in sequence according to the proportions of 30%, 25%, 25%, 15%, and 5% of the total amount of silica respectively. After each addition, wait until the batch is mixed evenly before adding the next batch of silica. After all the silica is mixed evenly, gradually raise the temperature, keep nitrogen flowing throughout the process for protection, raise the temperature to 120°C, turn off the nitrogen, start to pump vacuum, with a vacuum degree of -0.09 Mpa, gradually raise the temperature to 155°C, and maintain for 1.5 hours. Then release the vacuum and switch to nitrogen flow; Cool the obtained product to below 100°C, discharge, filter, and obtain the silicone rubber masterbatch.

[0066] Example 3

[0067] Put 40 parts of raw methyl vinyl silicone rubber with a vinyl molar fraction of 0.05% and 60 parts of raw methyl vinyl silicone rubber with a vinyl molar fraction of 0.22%, and 3.3 parts of low-viscosity hydroxyl silicone oil with a hydroxyl content of 9 wt% (30 mm / s 2)Put it into a kneader and conduct nitrogen passivation treatment on the kneader; Mix 21 parts by mass of rice husk ash precipitated silica (Green Sugar AG, particle size: 5 - 6 nm, BET specific surface area: 49.4 m 2 / g, purity: ≥98.5%, pore volume: 0.174 cm 2 / g) and 21 parts of ordinary precipitated silica YX900A evenly. Add the mixed silica into the kneader in 5 portions respectively, and add them in portions according to the proportions of 30%, 25%, 25%, 15%, and 5% of the total amount of silica in sequence. After each addition, wait until the batch is evenly mixed before adding the next batch of silica. After all the silica is evenly mixed, gradually raise the temperature, protect with nitrogen throughout the process, raise the temperature to 120 °C, turn off the nitrogen, start to pump vacuum, the vacuum degree is -0.09 Mpa, gradually raise the temperature to 155 °C, and maintain for 1.5 hours, then relieve the vacuum and switch to nitrogen; Cool the obtained product to below 100 °C, discharge, filter, and obtain the silicone rubber masterbatch.

[0068] Example 4

[0069] Put 40 parts of methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.05% and 60 parts of methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.22%, and 3.3 parts of low-viscosity hydroxyl silicone oil with a hydroxyl content of 9 wt% (30 mm / s 2 ) into a kneader and conduct nitrogen passivation treatment on the kneader; Mix 14 parts by mass of rice husk ash precipitated silica (Green Sugar AG, particle size: 5 - 6 nm, BET specific surface area: 49.4 m 2 / g, purity: ≥98.5%, pore volume: 0.174 cm 2 / g) and 28 parts of ordinary precipitated silica YX900A evenly. Add the mixed silica into the kneader in 5 portions respectively, and add them in portions according to the proportions of 30%, 25%, 25%, 15%, and 5% of the total amount of silica in sequence. After each addition, wait until the batch of silica is evenly mixed before adding the next batch of silica. After all the silica is evenly mixed, gradually raise the temperature, protect with nitrogen throughout the process, raise the temperature to 120 °C, turn off the nitrogen, start to pump vacuum, the vacuum degree is -0.09 Mpa, gradually raise the temperature to 155 °C, and maintain for 1.5 hours, then relieve the vacuum and switch to nitrogen; Cool the obtained product to below 100 °C, discharge, filter, and obtain the silicone rubber masterbatch.

[0070] Properties of the silicone rubber masterbatch prepared in Examples 1 - 4

[0071]

[0072] Note: Hardness is measured in accordance with ASTM D-2240, tensile strength in accordance with ASTM D412, elongation at break in accordance with ASTM D412, and aging in accordance with ASTM D573.

[0073] As can be seen from the above data, the silicone rubber compound reinforced with rice husk ash-precipitated silica has better property retention after aging.

[0074] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A silicone rubber compound, characterized in that, the raw materials for preparing the silicone rubber compound consist of methyl vinyl silicone rubber raw rubber, silica, and a structure control agent. The silica accounts for 30-45% by weight of the raw rubber, the structure control agent accounts for 6-9% by weight of the silica, and the silica contains at least rice husk ash precipitated silica, and the rice husk ash precipitated silica accounts for 30-70% by weight of the silica; the methyl vinyl silicone rubber raw rubber is a mixture of a methyl vinyl silicone rubber raw rubber with a vinyl molar content of 0.03-0.08% and a methyl vinyl silicone rubber raw rubber with a vinyl molar content of 0.15-0.30% in a mass ratio of (1-3):(2-4); the structure control agent is medium-viscosity hydroxy silicone oil or low-viscosity hydroxy silicone oil, and the hydroxy content in the hydroxy silicone oil is 4-9.5 wt%.

2. The silicone rubber compound according to claim 1, characterized in that, the rice husk ash precipitated silica is iron oxide-coated rice husk ash precipitated silica.

3. The silicone rubber compound according to claim 1, characterized in that, the raw materials for preparing the silicone rubber compound consist of the following substances in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 42 parts of rice husk ash precipitated silica, and 3.3 parts of low-viscosity hydroxy silicone oil; the methyl vinyl silicone rubber raw rubber includes a methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.05% and a methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.22% in a mass ratio of 2:3; the hydroxy content of the low-viscosity hydroxy silicone oil is 9 wt%; or, the raw materials for preparing the silicone rubber compound consist of the following substances in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 28 parts of rice husk ash precipitated silica, 14 parts of non-rice husk ash precipitation method silica, and 3.3 parts of low-viscosity hydroxy silicone oil; the methyl vinyl silicone rubber raw rubber includes a methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.05% and a methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.22% in a mass ratio of 2:3; the hydroxy content of the low-viscosity hydroxy silicone oil is 9 wt%; or, the raw materials for preparing the silicone rubber compound consist of the following substances in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 21 parts of rice husk ash precipitated silica, 21 parts of non-rice husk ash precipitation method silica, and 3.3 parts of low-viscosity hydroxy silicone oil; the methyl vinyl silicone rubber raw rubber includes a methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.05% and a methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.22% in a mass ratio of 2:3; the hydroxy content of the low-viscosity hydroxy silicone oil is 9 wt%; or, The raw materials for preparing the silicone rubber compound are composed of the following substances in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 14 parts of rice husk ash precipitated silica, 28 parts of non-rice husk ash precipitated silica, and 3.3 parts of low-viscosity hydroxy silicone oil; the methyl vinyl silicone rubber raw rubber includes methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.05% and methyl vinyl silicone rubber raw rubber with a vinyl molar fraction of 0.22% in a mass ratio of 2:3; the hydroxy content of the low-viscosity hydroxy silicone oil is 9 wt%.

4. The silicone rubber compound according to any one of claims 1-3, characterized in that, the preparation raw materials further comprise a release agent, a heat-resistant agent and / or a flame retardant.

5. The preparation method of the silicone rubber compound according to any one of claims 1-4, characterized in that, comprises the following steps: (1) Mix methyl vinyl silicone rubber raw rubber and a structure control agent; (2) Add precipitated silica to the mixture obtained in step (1); (3) Heat the mixture obtained in step (2).

6. The preparation method according to claim 5, characterized in that, in step (1), under the protection of an inert gas, mix methyl vinyl silicone rubber raw rubber and a structure control agent.

7. The preparation method according to claim 5, characterized in that, in step (2), the precipitated silica is added in batches.

8. The preparation method according to any one of claims 5-7, characterized in that, in step (3), after the materials in step (2) are mixed evenly, conduct the first temperature rise, evacuate the vacuum after the temperature rise is completed, then conduct the second temperature rise and keep warm, and then release the vacuum, and cool down under the protection of an inert gas.

9. The preparation method according to claim 8, characterized in that, in step (3), an inert gas is passed through the whole process during the first temperature rise for protection.

10. The preparation method according to claim 8, characterized in that, in step (3), the temperature reached during the first temperature rise is 110-130 °C.

11. The preparation method according to claim 8, characterized in that, in step (3), after the vacuum is evacuated, the vacuum degree is -0.1~-0.05 MPa.

12. The preparation method according to claim 8, characterized in that, in step (3), the temperature reached during the second temperature rise is 145-165 °C.

13. The silicone rubber compound prepared by the preparation method according to any one of claims 5-12.

14. The application of the silicone rubber compound according to any one of claims 1-4 or the silicone rubber compound according to claim 13 in the preparation of silicone rubber.

15. The application according to claim 14, characterized in that, the silicone rubber is a high-temperature resistant seal.

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