Dip-moldable thermal shock resistant liquid silicone rubber, and preparation method and application thereof

Abstract

The invention belongs to the technical field of silicone rubber processing, and particularly relates to heat-shock-resistant liquid silicone rubber capable of being subjected to dip forming, a preparation method and application. The high-temperature-resistant silicone rubber comprises the following components 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 silicon resin, 20-50 parts of white carbon black, 0.01-0.05 part of a heat stabilizer and 0.01-0.5 part of a Karst catalyst, wherein the heat stabilizer is an imine bond-containing organic matter with different side groups; the liquid silicone rubber disclosed by the invention has relatively high thermal shock resistance, and the performance of the liquid silicone rubber is not obviously changed after the liquid silicone rubber is circularly immersed in a 100 DEG C mold for 4 hours, so that the service life of the liquid silicone rubber is prolonged, and the amount of deteriorated rubber liquid generated by thermal shock is reduced; the liquid silicone rubber still has processability after being stored for more than 6 hours at 80 DEG C, the storage performance of the liquid silicone rubber is improved, and the liquid silicone rubber can be quickly vulcanized and molded at 160 DEG C after being soaked in a mold to obtain a silicone rubber product.

Description

Technical Field

[0001] The invention belongs to the technical field of silicone rubber processing, and in particular relates to a heat-shock-resistant liquid silicone rubber that can be dip-formed, a preparation method and an application thereof. Background Art

[0002] Silicone rubber is a synthetic organic polymer with a special structure. Compared with ordinary rubber, it has better resistance to high and low temperatures, UV resistance, radiation resistance, weather resistance, electrical insulation and physiological inertness. Therefore, it is widely used in aerospace, medical and health care, and daily necessities. At present, silicone rubber is generally formed by injection, molding, calendaring and pouring, while the dipping molding process is widely used due to its simple molding process and equipment, low processing cost and easy processing. The preparation of liquid silicone rubber products by dipping process can meet customers' needs for various special-shaped products to meet the application of various fields.

[0003] The dipping process usually involves dipping the heated mold into liquid silicone rubber. Therefore, the prepared liquid silicone rubber is required to have high stability at a specific temperature, that is, its viscosity changes slowly at a specific temperature to ensure the controllability of the dipping process. Therefore, a suitable catalytic inhibition system must be selected. In dipping molding, repeated dipping of the hot mold will cause the temperature of the dipping glue to reach above 60°C. Common heat stabilizers such as acetylenic alcohols, maleic acid diene esters, and fumaric acid esters are difficult to exert an inhibitory effect at this temperature, causing the dipping liquid silicone rubber to gel and vulcanize before molding, ultimately resulting in product defects or even inability to process. Therefore, a reasonable catalytic inhibition system needs to be designed for dipping liquid silicone rubber to ensure that the liquid silicone rubber has high heat shock resistance. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned technology, the present invention provides a method for preparing a dip-moldable heat-shock-resistant liquid silicone rubber using a series of organic substances containing imines with different side groups as an inhibition system, the purpose of which is to improve the heat-shock resistance of the liquid silicone rubber, prolong the storage time of the liquid silicone rubber, and achieve stable processability of the liquid silicone rubber.

[0005] The present invention solves the technical problem by adopting the following technical solution: The present invention discloses a heat-shock-resistant liquid silicone rubber that can be dip-formed. The components, calculated by weight, include: Preferably, the vinyl silicone oil is a mixture of a vinyl-terminated silicone oil having a viscosity of 500-1500 mPa·s and a vinyl-terminated silicone oil having 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%.

[0006] Preferably, the vinyl content in the vinyl MQ silicone resin is 0.1%-4%, and the M / Q value is 0.6-0.9.

[0007] Preferably, 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%.

[0008] Preferably, 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 160-300 m 2 / g.

[0009] Preferably, 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.

[0010] The present invention discloses a method for preparing the above-mentioned heat-shock-resistant liquid silicone rubber capable of being dip-molded, comprising the following steps: 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.

[0011] Preferably, the dip-moldable heat-shock-resistant liquid silicone rubber can be stored for a long time at room temperature.

[0012] The present invention also discloses an application of the above-mentioned heat-shock-resistant liquid silicone rubber capable of being dip-molded; 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.

[0013] The beneficial effects of the present invention are mainly reflected in the following: A series of organic heat stabilizers with different structures and compositions are selected to have good compatibility with liquid silicone rubber, which improves the storage stability of liquid silicone rubber; at the same time, the process is optimized to improve the thermal shock resistance of the system, which effectively prolongs the operation time of the impregnated silicone rubber system and ensures stable processing performance. When the liquid silicone rubber reaches the preset temperature, it can be quickly vulcanized and formed into silicone rubber products in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a viscosity variation trend diagram of the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Examples 1-16 of the present invention at 80°C. DETAILED DESCRIPTION

[0015] The following describes the implementation of the present invention through specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0016] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make disclosure thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. If not otherwise specified, the "%" and "parts" shown in the following examples refer to "mass %" and "mass parts" respectively.

[0017] The present invention uses Schiff base organic substances 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 to silicone rubber dipping molding and other special fields.

[0018] The present invention provides a heat-shock-resistant liquid silicone rubber capable of being dip-molded and a preparation method thereof, which comprises at least raw materials such as vinyl silicone oil, hydrogen-containing silicone oil, MQ silicone resin, white carbon black, a Custer catalyst, and a heat stabilizer. The liquid silicone rubber obtained by the present invention has good heat-shock resistance and good storage stability at a higher temperature, thereby increasing the operability space during dip molding.

[0019] In one embodiment of the present invention, in the dip-moldable heat-shock-resistant 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, wherein the mass ratio of the terminal vinyl silicone oil with a viscosity of 500-1500 mPa·s and 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.

[0020] In one embodiment of the present invention, in the dip-moldable heat-shock-resistant 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 above range of 5 parts, 15 parts or 20 parts.

[0021] In one embodiment of the present invention, in the dip-moldable heat-shock-resistant liquid silicone rubber, 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 side hydrogen-containing silicone oil has a viscosity of 10-50 mPa·s, and a hydrogen content of 0.3%-1%, and the end hydrogen-containing silicone oil has a viscosity of 50-500 mPa·s, and a hydrogen content of 0.01%-0.3%; for example, 10 parts of end side 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.

[0022] In one embodiment of the present invention, in the dip-moldable heat-shock resistant liquid silicone rubber, the content of the Custer catalyst is 0.01-0.5 parts. For example, the mass fraction of the Custer catalyst can be any value within the above range, such as 0.01 parts, 0.05 parts or 0.10 parts.

[0023] In one embodiment of the present invention, in the heat-shock-resistant liquid silicone rubber that can be dip-molded, 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 160-300 m 2 / g, for example, choose a specific surface area of ​​200m 2 / g of fumed silica as a reinforcing filler; the content of fumed silica is 20-50 parts by mass, for example, the mass fraction of fumed silica can be 30 parts or 40 parts, or any other value within the above range.

[0024] In one embodiment of the present invention, in the dip-moldable heat-shock-resistant liquid silicone rubber, the content of the heat stabilizer is 0.01-0.05 parts, and the type of the heat stabilizer is one of the mononitrogen system, the dinitrogen system, the sulfur-nitrogen system and the oxygen-nitrogen system; for example, the dinitrogen system is 0.02 parts.

[0025] The present invention provides a method for preparing a heat-shock-resistant liquid silicone rubber capable of being dip-molded, comprising the following steps: 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.

[0026] 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.

[0027] Example 1

[0028] 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2 hours, then 0.02 parts of a heat stabilizer was added and stirred, 0.01 parts of a Custer catalyst, 10 parts of a side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 3 hours, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a dimethyl nitrogen Schiff base, and the specific structural formula is: .

[0029] Example 2 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2 hours, then 0.02 parts of a heat stabilizer was added and stirred, 0.01 parts of a Custer catalyst, 10 parts of a side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 3 hours, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a dimethyl dinitrogen Schiff base, and the specific structural formula is: .

[0030] Example 3 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2 hours, then 0.02 parts of a heat stabilizer was added and stirred, 0.01 parts of a Custer catalyst, 10 parts of a side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 3 hours, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a dimethylsulfur-nitrogen Schiff base, and the specific structural formula is: .

[0031] Example 4 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2 hours, then 0.02 parts of a heat stabilizer was added and stirred, 0.01 parts of a Custer catalyst, 10 parts of a side hydrogen-containing silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 1%, and 20 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200 mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 3 hours, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a dimethyloxygen-nitrogen Schiff base, and the specific structural formula is: .

[0032] Example 5 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 10 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 20 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a mononitrogen Schiff base containing a hydroxyl group, and the specific structural formula is: .

[0033] Example 6 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 a specific surface area of ​​300 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 10 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 20 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a dinitrogen Schiff base containing a hydroxyl group, and the specific structural formula is: .

[0034] Example 7 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 a specific surface area of ​​300 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 15 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 20 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a sulfur-nitrogen Schiff base containing a hydroxyl group, and the specific structural formula is: .

[0035] Example 8 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 a specific surface area of ​​300 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 15 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 20 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is an oxygen-nitrogen Schiff base containing a hydroxyl group, and the specific structural formula is: .

[0036] Example 9 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 a specific surface area of ​​300 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 20 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 30 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a diphenyl nitrogen Schiff base, and the specific structural formula is: .

[0037] Example 10 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 a specific surface area of ​​300 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 20 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 30 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a bisphenyl dinitrogen Schiff base, and the specific structural formula is: .

[0038] Embodiment 11 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 20 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 30 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a Schiff base of diphenyloxy nitrogen, and the specific structural formula is: .

[0039] Example 12 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 20 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 30 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a Schiff base of diphenylsulfuronium nitrogen, and the specific structural formula is: .

[0040] Embodiment 13 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 20 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 30 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a diisopropyl mononitrogen Schiff base, and the specific structural formula is: .

[0041] Embodiment 14 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 20 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 30 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a diisopropyl dinitrogen Schiff base, and the specific structural formula is: .

[0042] Embodiment 15 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 20 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 30 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a diisopropylsulfur-nitrogen Schiff base, and the specific structural formula is: .

[0043] Example 16 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 a specific surface area of ​​200 m 2 / g of fumed silica was added into a kneader and kneaded for 2h, then 0.02 parts of a heat stabilizer was added and stirred, 0.1 parts of a Custer catalyst, 20 parts of a side hydrogen-containing silicone oil with a viscosity of 50mPa·s and a hydrogen content of 1%, and 30 parts of a terminal hydrogen-containing silicone oil with a viscosity of 200mPa·s and a hydrogen content of 0.2% were added, and stirring was continued for 2h, and finally vacuum degassing and filtering were performed to obtain a heat-shock-resistant liquid silicone rubber that can be dip-molded; Among them, the heat stabilizer is a diisopropyloxy-nitrogen Schiff base, and the specific structural formula is: .

[0044] Embodiment 17 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 1, left for 60 seconds, taken out, and vulcanized at 160°C for 120 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0045] Embodiment 18 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 2, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 150 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0046] Embodiment 19 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 3, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 100 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0047] Embodiment 20 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 4, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 180 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0048] Embodiment 21 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 5, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 180 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0049] Embodiment 22 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 6, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 180 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0050] Embodiment 23 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 7, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 180 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0051] Embodiment 24 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 8, left for 80 seconds, taken out, and placed at 160°C for vulcanization for 120 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0052] Embodiment 25 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 9, left for 80 seconds, taken out, and placed at 160°C for vulcanization for 150 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0053] Embodiment 26 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 10, left for 80 seconds, taken out, and placed at 160°C for vulcanization for 150 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and subjected to secondary vulcanization at 160°C for 2 hours to obtain a silicone rubber product.

[0054] Embodiment 27 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 11, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 90 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0055] Embodiment 28 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 12, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 150 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0056] Embodiment 29 The mold preheated to 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 13, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 120 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and subjected to secondary vulcanization at 160°C for 2 hours to obtain a silicone rubber product.

[0057] Embodiment 30 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 14, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 180 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0058] Embodiment 31 The mold preheated at 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 15, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 180 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and secondary vulcanized at 160°C for 2 hours to obtain a silicone rubber product.

[0059] Embodiment 32 The mold preheated to 200°C was immersed in the dip-moldable heat-shock-resistant liquid silicone rubber prepared in Example 16, left for 60 seconds, taken out, and placed at 160°C for vulcanization for 180 seconds. After the vulcanization was completed, it was taken out, cooled, removed from the mold, and subjected to secondary vulcanization at 160°C for 2 hours to obtain a silicone rubber product.

[0060] Test Case (1) Viscosity stability test: The heat-shock-resistant liquid silicone rubber prepared in Examples 1-16 was placed at 80°C, taken out every 1 hour, and its viscosity was tested using a rotational viscometer. The average value was obtained by performing three tests each time. The viscosity change trend is shown in the following figure: Figure 1 As shown in the figure, the time when the viscosity reaches 15000 mPa·s is taken as the storage time of the dip-molded heat-shock-resistant liquid silicone rubber at 80°C. The measurement results of the storage time are shown in Table 1: Table 1 Storage time Storage time Example 1 5h Example 9 7h Example 2 6h Example 10 8h Example 3 5h Embodiment 11 8h Example 4 5h Example 12 8h Example 5 ＞12h Example 13 9h Example 6 ＞12h Embodiment 14 8h Example 7 ＞12h Embodiment 15 7h Example 8 ＞12h Example 16 7h Depend on Figure 1 As shown in Table 1, the presence of heat stabilizer allows the dip-moldable heat shock resistant liquid silicone rubber to have a certain storage time at 80°C, especially the dinitrogen system heat stabilizer makes the viscosity change trend of the dip-moldable heat shock resistant liquid silicone rubber at 80°C yeast, the storage time reaches more than 6h, among which the dip-moldable heat shock resistant liquid silicone rubber containing hydroxyl heat stabilizer can reach a viscosity of 15000mPa·S after being placed at 80°C for about 12h, which has excellent heat shock resistance, greatly improves the operating time, prolongs the service life of the dip-moldable heat shock resistant liquid silicone rubber, and reduces the amount of deterioration caused by heat shock.

[0061] (2) Mechanical properties 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 dip-molded heat-resistant shock-resistant liquid silicone rubber prepared in Examples 1-16, respectively) were tested and characterized according to the method in reference standard GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", and the Shore hardness was tested and characterized according to the method in reference standard GB / T531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber Part 1: Shore durometer method (Shore hardness)". The mechanical properties test results are shown in Table 2: Table 2 Tensile strength / MPa Elongation at break / % Shore hardness / HA Tensile strength / MPa Elongation at break / % Shore hardness / HA Embodiment 17 3.78 387.25 31 Embodiment 25 3.55 361.54 31 Embodiment 18 3.65 362.41 33 Embodiment 26 3.42 342.73 30 Embodiment 19 3.71 371.57 32 Embodiment 27 3.51 358.26 30 Embodiment 20 3.52 358.41 31 Embodiment 28 3.35 328.60 28 Embodiment 21 2.95 312.36 25 Embodiment 29 3.27 319.81 27 Embodiment 22 2.82 302.57 25 Embodiment 30 3.48 347.67 31 Embodiment 23 2.87 310.27 25 Embodiment 31 3.39 338.05 30 Embodiment 24 2.91 310.69 25 Embodiment 32 3.30 321.53 29 As can be seen from Table 2, the silicone rubber products made from the heat-shock-resistant liquid silicone rubber that can be dip-molded prepared by the present invention have good mechanical properties. When the liquid silicone rubber is dip-molded at 160°C and secondary vulcanized, the tensile strength of the silicone rubber products reaches above 2.8MPa, and the Shore hardness reaches above 25HA, and the performance of the silicone rubber products meets the actual application requirements.

[0062] (3) Swelling performance test: The silicone rubber products prepared in Examples 17-32 were tested for solvent resistance. The test method includes: immersing a weighed sample (referred to as W1, accurate to 0.1 mg) in a brown wide-mouthed frosted glass bottle with a stopper containing toluene solvent, and placing it in a constant temperature water bath at 30±1°C for about 4 hours to allow it to reach swelling equilibrium; taking out the sample, wiping off the surface solvent with dry filter paper, and immediately weighing it (referred to as W2); then placing the weighed swollen sample in a forced air drying oven at 80°C for about 6 hours until the mass no longer changes, and weighing the dried sample for the third time (referred to as W3); The dissolution rate and swelling ratio of silicone rubber are calculated according to Formula 1 and Formula 2 respectively: Dissolution rate = (W1-W3) / W1 (Formula 1); Swelling ratio = W2 / W3 (Formula 2); The dissolution rate and swelling ratio test results are shown in Table 3: Table 3 Dissolution rate / % Swelling ratio Dissolution rate / % Swelling ratio Embodiment 17 5.27 3.23 Embodiment 25 5.72 3.33 Embodiment 18 5.39 3.30 Embodiment 26 5.83 3.62 Embodiment 19 5.05 3.15 Embodiment 27 5.85 3.71 Embodiment 20 5.64 3.56 Embodiment 28 5.79 3.75 Embodiment 21 7.52 3.87 Embodiment 29 5.80 3.73 Embodiment 22 7.35 3.79 Embodiment 30 5.86 3.69 Embodiment 23 7.21 3.81 Embodiment 31 5.79 3.63 Embodiment 24 7.26 3.83 Embodiment 32 5.75 3.59 As can be seen from Table 3, the dissolution rate and swelling ratio of the silicone rubber product obtained by vulcanizing the dip-moldable heat-shock-resistant liquid silicone rubber prepared by the present invention at 160°C prove that the silicone rubber product has a high degree of vulcanization, indicating that the addition of the heat stabilizer does not affect the molding process of the dip-moldable heat-shock-resistant liquid silicone rubber, and a completely vulcanized silicone rubber product can be obtained.

[0063] 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 do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only 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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