An impregnable molding heat shock resistant liquid silicone rubber, preparation method and application

Abstract

The present invention belongs to the technical field of silicone rubber processing, and specifically relates to a heat-shock-resistant liquid silicone rubber capable of dip molding, a preparation method and an application. Each component is included in parts by mass: 40-150 parts of vinyl silicone oil, 10-40 parts of hydrogen-containing silicone oil, 5-20 parts of vinyl MQ silicone resin, 20-50 parts of fumed silica, 0.01-0.05 parts of heat stabilizer and 0.01-0.5 parts of Karstedt catalyst, and the heat stabilizer is an organic substance containing imine bonds with different side groups; the liquid silicone rubber of the present invention has a relatively high heat-shock strength. After being immersed in a 100 °C mold for 4 h in a cycle, the performance does not change significantly, the service life of the liquid silicone rubber is prolonged, and the amount of deteriorated rubber liquid generated due to heat shock is reduced; it still has processability after being stored at 80 °C for more than 6 h, the storage performance of the liquid silicone rubber is improved, and after being impregnated on the mold, it can be quickly vulcanized and molded at 160 °C to obtain a silicone rubber product.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicone rubber processing, and particularly relates to an impregnable heat-resistant impact liquid silicone rubber, a preparation method and an application thereof. Background Art

[0002] As a synthetic organic polymer with a special structure, silicone rubber has better properties such as high and low temperature resistance, ultraviolet resistance, radiation resistance, weather resistance, electrical insulation and physiological inertness compared with ordinary rubber. Therefore, it is widely used in aerospace, medical and health, daily necessities and other aspects. At present, silicone rubber generally adopts forming processes such as injection, molding, calendering and casting. The impregnation molding process is widely used because of its simple forming process and equipment, low processing cost and easy processing. Preparing liquid silicone rubber products by the impregnation process can meet the needs of customers for various special-shaped products to meet the applications in various fields.

[0003] The impregnation process usually involves immersing the heated mold in liquid silicone rubber. Therefore, it is required that the prepared liquid silicone rubber can still have high stability at a specific temperature, that is, at a specific temperature, its viscosity changes slowly to ensure the controllability of the impregnation process. Therefore, a suitable catalytic inhibition system must be selected. In impregnation molding, since the hot mold is repeatedly immersed, the temperature of the impregnated adhesive solution will reach above 60°C. Common heat stabilizers such as alkynols, maleic acid diallyl esters, fumaric acid esters, etc. are difficult to play an inhibitory effect at this temperature, resulting in gelation and vulcanization of the impregnated liquid silicone rubber adhesive solution before molding, ultimately leading to product defects and even inability to process. Therefore, a reasonable catalytic inhibition system needs to be designed for the impregnated liquid silicone rubber to ensure that the liquid silicone rubber adhesive solution has high heat-resistant impact strength. Summary of the Invention

[0004] In order to overcome the deficiencies existing in the above technology, the present invention provides a preparation method of an impregnable heat-resistant impact liquid silicone rubber using a series of organic compounds containing imine with different side groups as an inhibition system, aiming to improve the heat-resistant impact strength of the liquid silicone rubber, extend the storage time of the liquid silicone rubber, and achieve stable processability of the liquid silicone rubber.

[0005] The present invention solves the technical problems by adopting the following technical solutions:

[0006] The present invention discloses an impregnable heat-resistant impact liquid silicone rubber, and each component is calculated by mass fraction and includes:

[0007] Preferably, the vinyl silicone oil is a mixture of a terminal vinyl silicone oil with a viscosity of 500 - 1500 mPa·s and a terminal vinyl silicone oil with a viscosity of 3000 - 5000 mPa·s;

[0008] Among them, the mass ratio of the vinyl-terminated silicone oil with a viscosity of 500 - 1500 mPa·s to the vinyl-terminated silicone oil with a viscosity of 3000 - 5000 mPa·s is 1:2 - 1:8. The vinyl content in the vinyl-terminated silicone oil with a viscosity of 500 - 1500 mPa·s is 0.29% - 0.42%, and the vinyl content in the vinyl-terminated silicone oil with a viscosity of 3000 - 5000 mPa·s is 0.15% - 0.25%.

[0009] Preferably, the vinyl content in the vinyl MQ silicone resin is 0.1% - 4%, and the M / Q value is 0.6 - 0.9.

[0010] Preferably, the hydrogen-containing silicone oil is a mixture of side-hydrogen-containing silicone oil and end-hydrogen-containing silicone oil;

[0011] Among them, the mass ratio of the side-hydrogen-containing silicone oil to the end-hydrogen-containing silicone oil is 1:1 - 1:4. The viscosity of the side-hydrogen-containing silicone oil is 10 - 50 mPa·s, and the hydrogen content is 0.3% - 1%. The viscosity of the end-hydrogen-containing silicone oil is 50 - 500 mPa·s, and the hydrogen content is 0.01% - 0.3%.

[0012] Preferably, the fumed silica is fumed silica, and the specific surface area range of the fumed silica is 160 - 300 m 2 / g.

[0013] Preferably, the heat stabilizer is any one of mono-nitrogen Schiff base, bis-nitrogen Schiff base, sulfur-nitrogen Schiff base, and oxygen-nitrogen Schiff base, and the specific structures are as follows:

[0014] ;

[0015] Among them, the structure of R 1 includes:

[0016] 、 、 、 any one of the four structures;

[0017] The structure of R 2 includes:

[0018] 、 、 、 any one of the four structures.

[0019] The present invention discloses a preparation method of the impregnable molding heat shock resistant liquid silicone rubber as described above, comprising the following steps:

[0020] Add vinyl-terminated silicone oil, vinyl MQ silicone resin, and fumed silica into a kneader, knead for 2 h, then add a heat stabilizer and stir. After stirring is completed, add hydrogen-containing silicone oil and Karstedt catalyst, and continue stirring for 1 - 3 h. After stirring is completed, perform vacuum degassing and filtration to obtain an impregnable and heat shock-resistant liquid silicone rubber.

[0021] Preferably, the impregnable and heat shock-resistant liquid silicone rubber can meet long-term storage at room temperature.

[0022] The present invention also discloses an application of the impregnable and heat shock-resistant liquid silicone rubber as described above;

[0023] The application includes preparing silicone rubber products using the impregnable and heat shock-resistant liquid silicone rubber;

[0024] The silicone rubber products are prepared by an impregnation molding process, which specifically includes the following steps:

[0025] Immerse a mold preheated to 200 °C into the impregnable and heat shock-resistant liquid silicone rubber. After standing for 60 - 180 s, take it out, place it at 160 °C for vulcanization, and the vulcanization time is 60 - 180 s. After vulcanization is completed, take it out, cool it, and remove it from the mold. Then perform secondary vulcanization at 160 °C for 2 h to obtain silicone rubber products.

[0026] The beneficial effects of the present invention are mainly reflected in the following:

[0027] A series of organic heat stabilizers with different structures and compositions are preferably selected, which have good compatibility with the liquid silicone rubber and improve the storage stability of the liquid silicone rubber. At the same time, the process is optimized, so that the heat shock resistance of the system is improved, the operation time of the impregnated silicone rubber system is preferably extended, and stable processing performance is ensured. When the liquid silicone rubber reaches the preset temperature, it can be quickly vulcanized and molded into silicone rubber products in a short time. Description of the Drawings

[0028] Figure 1 It is a graph showing the viscosity change trend of the impregnable and heat shock-resistant liquid silicone rubber prepared in Examples 1 - 16 of the present invention at 80 °C. Specific Embodiments

[0029] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0030] It should be understood that the present invention can be implemented in different forms and should not be construed as limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Unless otherwise specified, the "%" and "parts" shown in the following embodiments respectively refer to "mass %" and "parts by mass".

[0031] The present invention uses Schiff base organic compounds with different structures as heat stabilizers to improve the storage time and heat shock resistance of liquid silicone rubber at high temperatures, and can be well applied in silicone rubber impregnation molding and other special fields.

[0032] A heat shock-resistant impregnable liquid silicone rubber provided by the present invention and a preparation method thereof at least include raw materials such as vinyl silicone oil, hydrogen-containing silicone oil, MQ silicone resin, fumed silica, Karstedt catalyst, and heat stabilizer. The liquid silicone rubber obtained by the present invention has good heat shock resistance and good storage stability at higher temperatures, improving the operable space during impregnation molding.

[0033] In an embodiment of the present invention, in the heat shock-resistant impregnable liquid silicone rubber, the vinyl silicone oil is a mixture of a terminal vinyl silicone oil with a viscosity of 500 - 1500 mPa·s and a terminal vinyl silicone oil with a viscosity of 3000 - 5000 mPa·s. Among them, the mass ratio of the terminal vinyl silicone oil with a viscosity of 500 - 1500 mPa·s to the terminal vinyl silicone oil with a viscosity of 3000 - 5000 mPa·s is 1:2 - 1:8, the vinyl content of the terminal vinyl silicone oil with a viscosity of 500 - 1500 mPa·s is 0.29% - 0.42%, and the vinyl content of the terminal vinyl silicone oil with a viscosity of 3000 - 5000 mPa·s is 0.15% - 0.25%; for example, 20 parts of the terminal vinyl silicone oil with a viscosity of 1500 mPa·s and 40 parts of the terminal vinyl silicone oil with a viscosity of 5000 mPa·s.

[0034] In an embodiment of the present invention, in the heat shock-resistant impregnable liquid silicone rubber, the vinyl content in the vinyl MQ silicone resin is 0.1% - 4%, and the M / Q value is 0.6 - 0.9. For example, a vinyl MQ silicone resin with a vinyl content of 2% and an M / Q value of 0.8 is selected; the content of the vinyl MQ silicone resin is 5 - 20 parts by mass. For example, the mass fraction of the vinyl MQ silicone resin can be any value within the range of 5 parts, 15 parts, or 20 parts.

[0035] In one embodiment of the present invention, in the heat-resistant impact liquid silicone rubber that can be impregnated and molded, the hydrogen-containing silicone oil is a mixture of side-hydrogen-containing silicone oil and end-hydrogen-containing silicone oil, wherein the mass ratio of the side-hydrogen-containing silicone oil to the end-hydrogen-containing silicone oil is 1:1 - 1:4, the viscosity of the side-hydrogen-containing silicone oil is 10 - 50 mPa·s, the hydrogen content is 0.3% - 1%, the viscosity of the end-hydrogen-containing silicone oil is 50 - 500 mPa·s, and the hydrogen content is 0.01% - 0.3%; for example, 10 parts of side-end-hydrogen-containing silicone oil with a viscosity of 20 mPa·s and 20 parts of end-hydrogen-containing silicone oil with a viscosity of 200 mPa·s are selected.

[0036] In one embodiment of the present invention, in the heat-resistant impact liquid silicone rubber that can be impregnated and molded, the content of the Karstedt catalyst is 0.01 - 0.5 parts, and for another example, the mass fraction of the Karstedt catalyst can be any value within the above range, such as 0.01 part, 0.05 part or 0.10 part, etc.

[0037] In one embodiment of the present invention, in the heat-resistant impact liquid silicone rubber that can be impregnated and molded, the white carbon black is fumed white carbon black, and the specific surface area range of the fumed white carbon black is 160 - 300 m 2 / g, for example, fumed white carbon black with a specific surface area of 200 m 2 / g is selected as the reinforcing filler; the content of the fumed white carbon black is 20 - 50 parts by mass, and for example, the mass fraction of the fumed white carbon black can be any value within the above range, such as 30 parts or 40 parts, etc.

[0038] In one embodiment of the present invention, in the heat-resistant impact liquid silicone rubber that can be impregnated and molded, the content of the heat stabilizer is 0.01 - 0.05 parts, and the type of the heat stabilizer is one of the mono-nitrogen system, di-nitrogen system, sulfur-nitrogen system and oxygen-nitrogen system; for example, 0.02 parts of the di-nitrogen system.

[0039] The present invention provides a preparation method of a heat-resistant impact liquid silicone rubber that can be impregnated and molded, comprising the following steps:

[0040] Add the end-vinyl silicone oil, vinyl MQ silicone resin and white carbon black into a kneader, knead for 2 h, then add the heat stabilizer and stir. After the stirring is completed, add the hydrogen-containing silicone oil and the Karstedt catalyst, and continue to stir for 1 - 3 h. After the stirring is completed, perform vacuum degassing and filtration to obtain the heat-resistant impact liquid silicone rubber that can be impregnated and molded.

[0041] The application includes using the heat-resistant impact liquid silicone rubber that can be impregnated and molded to prepare silicone rubber products;

[0042] The silicone rubber products are prepared by an impregnation molding process, specifically comprising the following steps:

[0043] Immerse a mold preheated to 200 °C in a heat-resistant impact liquid silicone rubber for impregnation molding. After standing for 60 - 180 s, take it out and place it at 160 °C for vulcanization. The vulcanization time is 60 - 180 s. After vulcanization is completed, take it out, cool it, and then remove it from the mold. Conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0044] Example 1

[0045] Add 20 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 40 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 5 parts of MQ silicone resin with a vinyl content of 2% and an M / Q value of 0.8, and 20 parts of fumed silica with a specific surface area of 200 m 2 / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Add 0.01 parts of Karstedt catalyst, 10 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 3 h. Finally, conduct vacuum degassing and filtration to obtain a heat-resistant impact liquid silicone rubber for impregnation molding;

[0046] Among them, the heat stabilizer is a dimethyl mono-nitrogen Schiff base, and the specific structural formula is:

[0047] .

[0048] Example 2

[0049] Add 20 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 40 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 5 parts of MQ silicone resin with a vinyl content of 2% and an M / Q value of 0.8, and 30 parts of fumed silica with a specific surface area of 200 m 2 / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Add 0.01 parts of Karstedt catalyst, 10 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 3 h. Finally, conduct vacuum degassing and filtration to obtain a heat-resistant impact liquid silicone rubber for impregnation molding;

[0050] Among them, the heat stabilizer is a dimethyl di-nitrogen Schiff base, and the specific structural formula is:

[0051] .

[0052] Example 3

[0053] Add 20 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 40 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 5 parts of MQ silicone resin with a vinyl content of 2% and an M / Q value of 0.8, and 25 parts of fumed silica with a specific surface area of 200 m 2 / g into a kneader, knead for 2 h, then add 0.02 parts of heat stabilizer and stir, add 0.01 parts of Karstedt catalyst, 10 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%, continue to stir for 3 h, and finally perform vacuum degassing and filtration to obtain an impregnable and heat-shock-resistant liquid silicone rubber;

[0054] Among them, the heat stabilizer is a dimethylthionitrogen Schiff base, and the specific structural formula is:

[0055] 。

[0056] Example 4

[0057] Add 20 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 40 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 5 parts of MQ silicone resin with a vinyl content of 2% and an M / Q value of 0.8, and 25 parts of fumed silica with a specific surface area of 200 m 2 / g into a kneader, knead for 2 h, then add 0.02 parts of heat stabilizer and stir, add 0.01 parts of Karstedt catalyst, 10 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%, continue to stir for 3 h, and finally perform vacuum degassing and filtration to obtain an impregnable and heat-shock-resistant liquid silicone rubber;

[0058] Among them, the heat stabilizer is a dimethyloxonitrogen Schiff base, and the specific structural formula is:

[0059] 。

[0060] Example 5

[0061] Add 30 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 60 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 10 parts of MQ silicone resin with a vinyl content of 0.5% and an M / Q value of 0.6, and 25 parts of fumed silica with a specific surface area of 200 m 2Add fumed silica with a specific surface area of 300 m² / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Next, add 0.1 part of Karstedt catalyst, 10 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h. Finally, perform vacuum degassing and filtration to obtain a heat-resistant impact liquid silicone rubber that can be impregnated and molded;

[0062] Among them, the heat stabilizer is a mono-nitrogen Schiff base containing a hydroxyl group, and the specific structural formula is:

[0063] 。

[0064] Example 6

[0065] Add 30 parts of end vinyl silicone oil with a viscosity of 1500 mPa·s, 60 parts of end vinyl silicone oil with a viscosity of 5000 mPa·s, 10 parts of MQ silicone resin with a vinyl content of 0.5% and an M / Q value of 0.6, and 25 parts of fumed silica with a specific surface area of 300 m 2 / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Next, add 0.1 part of Karstedt catalyst, 10 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h. Finally, perform vacuum degassing and filtration to obtain a heat-resistant impact liquid silicone rubber that can be impregnated and molded;

[0066] Among them, the heat stabilizer is a bis-nitrogen Schiff base containing a hydroxyl group, and the specific structural formula is:

[0067] 。

[0068] Example 7

[0069] Add 30 parts of end vinyl silicone oil with a viscosity of 1500 mPa·s, 60 parts of end vinyl silicone oil with a viscosity of 5000 mPa·s, 10 parts of MQ silicone resin with a vinyl content of 0.5% and an M / Q value of 0.6, and 25 parts of fumed silica with a specific surface area of 300 m 2 / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Next, add 0.1 part of Karstedt catalyst, 15 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h. Finally, perform vacuum degassing and filtration to obtain a heat-resistant impact liquid silicone rubber that can be impregnated and molded;

[0070] Among them, the heat stabilizer is a sulfur-nitrogen Schiff base containing a hydroxyl group, and the specific structural formula is:

[0071] .

[0072] Example 8

[0073] Add 30 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 60 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 10 parts of MQ silicone resin with a vinyl content of 0.5% and an M / Q value of 0.6, and 25 parts of fumed silica with a specific surface area of 300 m 2 / g into a kneader, knead for 2 h, then add 0.02 parts of heat stabilizer and stir, add 0.1 part of Karstedt catalyst, 15 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%, continue to stir for 2 h, and finally perform vacuum degassing and filtration to obtain an impregnable and moldable heat-resistant shock liquid silicone rubber;

[0074] Among them, the heat stabilizer is an oxime Schiff base containing hydroxyl groups, and the specific structural formula is:

[0075] .

[0076] Example 9

[0077] Add 25 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 50 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 15 parts of MQ silicone resin with a vinyl content of 1% and an M / Q value of 0.7, and 30 parts of fumed silica with a specific surface area of 300 m 2 / g into a kneader, knead for 2 h, then add 0.02 parts of heat stabilizer and stir, add 0.1 part of Karstedt catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%, continue to stir for 2 h, and finally perform vacuum degassing and filtration to obtain an impregnable and moldable heat-resistant shock liquid silicone rubber;

[0078] Among them, the heat stabilizer is a biphenyl monoazide Schiff base, and the specific structural formula is:

[0079] .

[0080] Example 10

[0081] Add 25 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 50 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 15 parts of MQ silicone resin with a vinyl content of 1% and an M / Q value of 0.7, and 30 parts of fumed silica with a specific surface area of 300 m 2Add fumed silica with a specific surface area of 200 m² / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Next, add 0.1 part of Karstedt's catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h. Finally, perform vacuum degassing and filtration to obtain a heat-resistant shock liquid silicone rubber that can be impregnated and molded;

[0082] Among them, the heat stabilizer is a biphenyl bis-nitrogen Schiff base, and the specific structural formula is:

[0083] 。

[0084] Example 11

[0085] Add 25 parts of terminal vinyl silicone oil with a viscosity of 1500 mPa·s, 50 parts of terminal vinyl silicone oil with a viscosity of 5000 mPa·s, 15 parts of MQ silicone resin with a vinyl content of 1% and an M / Q value of 0.7, and 30 parts of fumed silica with a specific surface area of 200 m² / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Next, add 0.1 part of Karstedt's catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h. Finally, perform vacuum degassing and filtration to obtain a heat-resistant shock liquid silicone rubber that can be impregnated and molded; 2 Add fumed silica with a specific surface area of 200 m² / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Next, add 0.1 part of Karstedt's catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h. Finally, perform vacuum degassing and filtration to obtain a heat-resistant shock liquid silicone rubber that can be impregnated and molded;

[0086] Among them, the heat stabilizer is a biphenyl oxynitrogen Schiff base, and the specific structural formula is:

[0087] 。

[0088] Example 12

[0089] Add 25 parts of terminal vinyl silicone oil with a viscosity of 1500 mPa·s, 50 parts of terminal vinyl silicone oil with a viscosity of 5000 mPa·s, 15 parts of MQ silicone resin with a vinyl content of 1% and an M / Q value of 0.7, and 30 parts of fumed silica with a specific surface area of 200 m² / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Next, add 0.1 part of Karstedt's catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h. Finally, perform vacuum degassing and filtration to obtain a heat-resistant shock liquid silicone rubber that can be impregnated and molded; 2 Add fumed silica with a specific surface area of 200 m² / g into a kneader and knead for 2 h. Then add 0.02 parts of heat stabilizer and stir. Next, add 0.1 part of Karstedt's catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h. Finally, perform vacuum degassing and filtration to obtain a heat-resistant shock liquid silicone rubber that can be impregnated and molded;

[0090] Among them, the heat stabilizer is a biphenyl thionitrogen Schiff base, and the specific structural formula is:

[0091] .

[0092] Example 13

[0093] Add 25 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 50 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 15 parts of MQ silicone resin with a vinyl content of 1% and an M / Q value of 0.7, and 30 parts of fumed silica with a specific surface area of 200 m 2 / g into a kneader, knead for 2 h, then add 0.02 parts of heat stabilizer and stir, add 0.1 parts of Karstedt catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%, continue to stir for 2 h, and finally perform vacuum degassing and filtration to obtain an impregnable and heat shock-resistant liquid silicone rubber;

[0094] Among them, the heat stabilizer is bis(isopropyl)monoazido Schiff base, and the specific structural formula is:

[0095] .

[0096] Example 14

[0097] Add 25 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 50 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 15 parts of MQ silicone resin with a vinyl content of 1% and an M / Q value of 0.7, and 30 parts of fumed silica with a specific surface area of 200 m 2 / g into a kneader, knead for 2 h, then add 0.02 parts of heat stabilizer and stir, add 0.1 parts of Karstedt catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of end hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%, continue to stir for 2 h, and finally perform vacuum degassing and filtration to obtain an impregnable and heat shock-resistant liquid silicone rubber;

[0098] Among them, the heat stabilizer is bis(isopropyl)diazido Schiff base, and the specific structural formula is:

[0099] .

[0100] Example 15

[0101] Add 25 parts of vinyl-terminated silicone oil with a viscosity of 1500 mPa·s, 50 parts of vinyl-terminated silicone oil with a viscosity of 5000 mPa·s, 15 parts of MQ silicone resin with a vinyl content of 1% and an M / Q value of 0.7, and 30 parts of fumed silica with a specific surface area of 200 m 2Add fumed silica at / g into a kneader, knead for 2 h, then add 0.02 part of heat stabilizer and stir. Add 0.1 part of Cast catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h, and finally perform vacuum degassing and filtration to obtain an impregnable and heat-shock-resistant liquid silicone rubber;

[0102] Among them, the heat stabilizer is a diisopropyl thionitrogen Schiff base, and the specific structural formula is:

[0103] 。

[0104] Example 16

[0105] Add 25 parts of terminal vinyl silicone oil with a viscosity of 1500 mPa·s, 50 parts of terminal vinyl silicone oil with a viscosity of 5000 mPa·s, 15 parts of MQ silicone resin with a vinyl content of 1% and an M / Q value of 0.7, and 30 parts of specific surface area of 200 m 2 Add fumed silica at / g into a kneader, knead for 2 h, then add 0.02 part of heat stabilizer and stir. Add 0.1 part of Cast catalyst, 20 parts of side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 30 parts of terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2%. Continue to stir for 2 h, and finally perform vacuum degassing and filtration to obtain an impregnable and heat-shock-resistant liquid silicone rubber;

[0106] Among them, the heat stabilizer is a diisopropyl oxonitrogen Schiff base, and the specific structural formula is:

[0107] 。

[0108] Example 17

[0109] Immerse a mold preheated to 200 °C into the impregnable and heat-shock-resistant liquid silicone rubber prepared in Example 1, let it stand for 60 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 120 s. After vulcanization is completed, take it out, cool it and remove it from the mold, and perform secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0110] Example 18

[0111] Immerse a mold preheated to 200 °C into the impregnable and heat-shock-resistant liquid silicone rubber prepared in Example 2, let it stand for 60 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 150 s. After vulcanization is completed, take it out, cool it and remove it from the mold, and perform secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0112] Example 19

[0113] Immerse the mold preheated to 200 °C into the impregnable heat-resistant impact liquid silicone rubber prepared in Example 3, let it stand for 60 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 100 s. After vulcanization is completed, take it out, cool it and remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0114] Example 20

[0115] Immerse the mold preheated to 200 °C into the impregnable heat-resistant impact liquid silicone rubber prepared in Example 4, let it stand for 60 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 180 s. After vulcanization is completed, take it out, cool it and remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0116] Example 21

[0117] Immerse the mold preheated to 200 °C into the impregnable heat-resistant impact liquid silicone rubber prepared in Example 5, let it stand for 60 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 180 s. After vulcanization is completed, take it out, cool it and remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0118] Example 22

[0119] Immerse the mold preheated to 200 °C into the impregnable heat-resistant impact liquid silicone rubber prepared in Example 6, let it stand for 60 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 180 s. After vulcanization is completed, take it out, cool it and remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0120] Example 23

[0121] Immerse the mold preheated to 200 °C into the impregnable heat-resistant impact liquid silicone rubber prepared in Example 7, let it stand for 60 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 180 s. After vulcanization is completed, take it out, cool it and remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0122] Example 24

[0123] Immerse the mold preheated to 200 °C into the impregnable and heat-resistant impact liquid silicone rubber prepared in Example 8, let it stand for 80 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 120 s. After vulcanization is completed, take it out, cool it and then remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0124] Example 25

[0125] Immerse the mold preheated to 200 °C into the impregnable and heat-resistant impact liquid silicone rubber prepared in Example 9, let it stand for 80 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 150 s. After vulcanization is completed, take it out, cool it and then remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0126] Example 26

[0127] Immerse the mold preheated to 200 °C into the impregnable and heat-resistant impact liquid silicone rubber prepared in Example 10, let it stand for 80 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 150 s. After vulcanization is completed, take it out, cool it and then remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0128] Example 27

[0129] Immerse the mold preheated to 200 °C into the impregnable and heat-resistant impact liquid silicone rubber prepared in Example 11, let it stand for 60 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 90 s. After vulcanization is completed, take it out, cool it and then remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0130] Example 28

[0131] Immerse the mold preheated to 200 °C into the impregnable and heat-resistant impact liquid silicone rubber prepared in Example 12, let it stand for 60 s, take it out, place it at 160 °C for vulcanization, the vulcanization time is 150 s. After vulcanization is completed, take it out, cool it and then remove it from the mold, and conduct secondary vulcanization at 160 °C for 2 h to obtain a silicone rubber product.

[0132] Example 29

[0133] The mold preheated to 200 °C was immersed in the impregnable heat-resistant impact liquid silicone rubber prepared in Example 13, parked for 60 s, taken out, placed at 160 °C for vulcanization, the vulcanization time was 120 s. After vulcanization was completed, it was taken out, cooled and removed from the mold, and secondary vulcanization was carried out at 160 °C for 2 h to obtain a silicone rubber product.

[0134] Example 30

[0135] The mold preheated to 200 °C was immersed in the impregnable heat-resistant impact liquid silicone rubber prepared in Example 14, parked for 60 s, taken out, placed at 160 °C for vulcanization, the vulcanization time was 180 s. After vulcanization was completed, it was taken out, cooled and removed from the mold, and secondary vulcanization was carried out at 160 °C for 2 h to obtain a silicone rubber product.

[0136] Example 31

[0137] The mold preheated to 200 °C was immersed in the impregnable heat-resistant impact liquid silicone rubber prepared in Example 15, parked for 60 s, taken out, placed at 160 °C for vulcanization, the vulcanization time was 180 s. After vulcanization was completed, it was taken out, cooled and removed from the mold, and secondary vulcanization was carried out at 160 °C for 2 h to obtain a silicone rubber product.

[0138] Example 32

[0139] The mold preheated to 200 °C was immersed in the impregnable heat-resistant impact liquid silicone rubber prepared in Example 16, parked for 60 s, taken out, placed at 160 °C for vulcanization, the vulcanization time was 180 s. After vulcanization was completed, it was taken out, cooled and removed from the mold, and secondary vulcanization was carried out at 160 °C for 2 h to obtain a silicone rubber product.

[0140] Test Example

[0141] (1) Viscosity stability test: The impregnable heat-resistant impact liquid silicone rubber prepared in Examples 1-16 was placed at 80 °C, taken out every 1 h, and its viscosity was measured using a rotational viscometer. The average value was obtained by measuring 3 times each time. The viscosity change trend is as Figure 1 shown. The time when the viscosity reached 15000 mPa·s was used as the storage time of the impregnable heat-resistant impact liquid silicone rubber at 80 °C. The measurement results of the storage time are shown in Table 1:

[0142] Table 1

[0143] Storage time Storage time Example 1 5h Example 9 7h Example 2 6h Example 10 8h Example 3 5h Example 11 8h Example 4 5h Example 12 8h Example 5 ＞12h Example 13 9h Example 6 ＞12h Example 14 8h Example 7 ＞12h Example 15 7h Example 8 ＞12h Example 16 7h

[0144] From Figure 1As can be seen from Table 1, the presence of heat stabilizers enables the impregnable heat-resistant impact liquid silicone rubber to have a certain storage time at 80°C. In particular, the heat stabilizers of the double-nitrogen system make the viscosity change trend of the impregnable heat-resistant impact liquid silicone rubber slower at 80°C, and the storage time reaches more than 6 hours. The impregnable heat-resistant impact liquid silicone rubber containing heat stabilizers with hydroxyl groups reaches a viscosity of about 15000 mPa·S after being placed at 80°C for about 12 hours. It has excellent heat-resistant impact strength, greatly improves the operable time, extends the service life of the impregnable heat-resistant impact liquid silicone rubber, and reduces the amount of deterioration caused by heat shock.

[0145] (2)Mechanical property test: The tensile strength, elongation at break and Shore hardness of the silicone rubber products prepared in Examples 17 - 32 (i.e., corresponding to the impregnable heat-resistant impact liquid silicone rubbers prepared in Examples 1 - 16 respectively) were tested. The tensile strength and elongation at break were tested and characterized according to the method in Standard GB / T528 - 2009 "Vulcanized rubber or thermoplastic rubber - Determination of tensile stress-strain properties", and the Shore hardness was tested and characterized according to the method in Standard GB / T531.1 - 2008 "Rubber, vulcanized or thermoplastic - Determination of indentation hardness - Part 1: Durometer method (Shore hardness)". The test results of mechanical properties are shown in Table 2:

[0146] Table 2

[0147] Tensile strength / MPa Elongation at break / % Shore hardness / HA Tensile strength / MPa Elongation at break / % Shore hardness / HA Example 17 3.78 387.25 31 Example 25 3.55 361.54 31 Example 18 3.65 362.41 33 Example 26 3.42 342.73 30 Example 19 3.71 371.57 32 Example 27 3.51 358.26 30 Example 20 3.52 358.41 31 Example 28 3.35 328.60 28 Example 21 2.95 312.36 25 Example 29 3.27 319.81 27 Example 22 2.82 302.57 25 Example 30 3.48 347.67 31 Example 23 2.87 310.27 25 Example 31 3.39 338.05 30 Example 24 2.91 310.69 25 Example 32 3.30 321.53 29

[0148] As can be seen from Table 2, the silicone rubber products prepared from the impregnable heat-resistant impact liquid silicone rubber prepared by the present invention have good mechanical properties. When the liquid silicone rubber is impregnated and formed at 160°C and then secondary vulcanized, the tensile strength of the silicone rubber products all reaches above 2.8 MPa, and the Shore hardness reaches above 25 HA. The properties of the silicone rubber products meet the actual application requirements.

[0149] (3)Swelling property test: The solvent resistance of the silicone rubber products prepared in Examples 17 - 32 was tested. The test method includes: immersing the weighed sample (denoted as W1, accurate to 0.1 mg) in a brown large-mouth stoppered frosted glass bottle filled with toluene solvent, placing it in a constant temperature water bath at 30 ± 1°C for about 4 hours to reach swelling equilibrium; taking out the sample, gently wiping off the surface solvent with a dry filter paper and immediately weighing it (denoted as W2); then placing the swollen sample after weighing in a blast drying oven at 80°C for about 6 hours until the mass no longer changes, and weighing the dried sample for the third time (denoted as W3);

[0150] The dissolution rate and swelling ratio of the silicone rubber are calculated according to the following formulas 1 and 2 respectively:

[0151] Dissolution rate = (W1 - W3) / W1 (Equation 1);

[0152] Swelling ratio = W2 / W3 (Equation 2);

[0153] The test results of the dissolution rate and swelling ratio are shown in Table 3 as follows:

[0154] Table 3

[0155] Dissolution rate / % Swelling ratio Dissolution rate / % Swelling ratio Example 17 5.27 3.23 Example 25 5.72 3.33 Example 18 5.39 3.30 Example 26 5.83 3.62 Example 19 5.05 3.15 Example 27 5.85 3.71 Example 20 5.64 3.56 Example 28 5.79 3.75 Example 21 7.52 3.87 Example 29 5.80 3.73 Example 22 7.35 3.79 Example 30 5.86 3.69 Example 23 7.21 3.81 Example 31 5.79 3.63 Example 24 7.26 3.83 Example 32 5.75 3.59

[0156] As can be seen from Table 3, for the silicone rubber product prepared by vulcanizing and molding the impregnable heat-resistant impact liquid silicone rubber prepared by the present invention at 160°C, its dissolution rate and swelling ratio prove that the degree of vulcanization of the silicone rubber product is high, indicating that the addition of the heat stabilizer does not affect the molding process of the impregnable heat-resistant impact liquid silicone rubber, and a fully vulcanized silicone rubber product can be obtained.

[0157] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A heat-shock-resistant liquid silicone rubber that can be dip-molded, characterized in that: The components are calculated by weight and include: 40-150 parts of vinyl silicone oil; 10-40 parts of hydrogen silicone oil; 5-20 parts of vinyl MQ silicone resin; 20-50 parts of white carbon black; Custer catalyst 0.01-0.5 parts; Heat stabilizer 0.01-0.05 parts; The heat stabilizer is any one of a mononitrogen Schiff base, a dinitrogen Schiff base, a sulfur-nitrogen Schiff base, and an oxygen-nitrogen Schiff base, and the specific structure is as follows: ； Wherein, the structure of R1 includes: , , , Any of the four structures; The structure of R2 includes: , , , Any of four structures.

2. The heat-shock-resistant liquid silicone rubber capable of being dip-molded according to claim 1, characterized in that: The vinyl silicone oil is a mixture of a vinyl-terminated silicone oil with a viscosity of 500-1500 mPa·s and a vinyl-terminated silicone oil with a viscosity of 3000-5000 mPa·s; Among them, the mass ratio of the vinyl-terminated silicone oil with a viscosity of 500-1500mPa·s and the vinyl-terminated silicone oil with a viscosity of 3000-5000mPa·s is 1:2-1:8, the vinyl content in the vinyl-terminated silicone oil with a viscosity of 500-1500mPa·s is 0.29%-0.42%, and the vinyl content in the vinyl-terminated silicone oil with a viscosity of 3000-5000mPa·s is 0.15%-0.25%.

3. The heat-shock-resistant liquid silicone rubber capable of being dip-molded according to claim 1, characterized in that: The vinyl content of the vinyl MQ silicone resin is 0.1%-4%, and the M / Q value is 0.6-0.

9.

4. The heat-shock-resistant liquid silicone rubber capable of being dip-molded according to claim 1, characterized in that: The hydrogen-containing silicone oil is a mixture of side hydrogen-containing silicone oil and terminal hydrogen-containing silicone oil; Among them, the mass ratio of side hydrogen-containing silicone oil to terminal hydrogen-containing silicone oil is 1:1-1:4, the viscosity of the side hydrogen-containing silicone oil is 10-50mPa·s, the hydrogen content is 0.3%-1%, the viscosity of the terminal hydrogen-containing silicone oil is 50-500mPa·s, and the hydrogen content is 0.01%-0.3%.

5. The heat-shock-resistant liquid silicone rubber capable of being dip-molded according to claim 1, characterized in that: The white carbon black is fumed white carbon black, and the specific surface area of ​​the fumed white carbon black is in the range of 160-300m 2 / g.

6. A method for preparing the dip-moldable heat-shock-resistant liquid silicone rubber according to any one of claims 1 to 5, characterized in that: The following steps are involved: Add terminal vinyl silicone oil, vinyl MQ silicone resin and white carbon black into a kneader, knead for 2 hours, then add a heat stabilizer and stir. After stirring, add hydrogen-containing silicone oil and Custer catalyst and continue stirring for 1-3 hours. After stirring, vacuum degassing and filtering are performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded.

7. An application of the dip-moldable heat-shock-resistant liquid silicone rubber according to any one of claims 1 to 5, characterized in that: The application includes preparing silicone rubber products by using the dip-molded heat-shock-resistant liquid silicone rubber; The silicone rubber product is prepared by a dipping molding process, which specifically includes the following steps: The mold preheated to 200°C is immersed in the dip-moldable heat-shock-resistant liquid silicone rubber, and after standing for 60-180s, it is taken out and placed at 160°C for vulcanization for 60-180s. After the vulcanization is completed, it is taken out and removed from the mold after cooling, and secondary vulcanization is performed at 160°C for 2h to obtain a silicone rubber product.

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