High-temperature-resistant organic silicon rubber composition and preparation process thereof

Abstract

The invention relates to the technical field of organic silicon rubber, and particularly discloses a high-temperature-resistant organic silicon rubber composition and a preparation process thereof.The high-temperature-resistant organic silicon rubber composition is prepared from vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, a functional monomer, a phosphorus-nitrogen-containing copolymer, a cross-linking agent and an accelerant; the preparation process comprises the following steps: premixing vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinyl pyrrolidone, adding a functional monomer and a phosphorus-nitrogen-containing copolymer, and continuously and uniformly mixing to obtain a mixture; heating the mixture, keeping the temperature and carrying out polymerization reaction, adding a cross-linking agent and an accelerant, uniformly mixing, injecting into a mold, and carrying out curing molding, so as to obtain the high-temperature-resistant organic silicon rubber composition. The flame retardant property and the high temperature resistance of the organic silicon rubber composition are remarkably enhanced, and the aging resistance and the mechanical strength of the organic silicon rubber composition in a high-temperature environment are also improved.

Description

Technical Field

[0001] The present application relates to the technical field of organic silicone rubber, and more specifically, to a high temperature resistant organic silicone rubber composition and a preparation process thereof. Background Art

[0002] With the continuous development of industrial technology, the demand for high temperature resistant materials is growing. Although traditional silicone rubber has certain advantages in high temperature resistance, it still has deficiencies in flame retardancy, mechanical properties and long-term stability. Therefore, it is particularly important to develop a silicone rubber composition with both superior high temperature resistance and flame retardancy.

[0003] At present, China's invention patent publication number CN117701006A discloses a high temperature resistant silicone rubber composition and its preparation process, which is prepared by adding dithiol DOPO intermediate, tri(alkenylnaphthalene) isocyanurate, and benzoin dimethyl ether to N,N-dimethylformamide for reaction, and then adding tri(alkenylnaphthalene) isocyanurate for reaction and end-capping to obtain an alkenyl-end-capped isocyanurate-DOPO polymer; then methyl vinyl silicone rubber, methyl silicone oil, isocyanurate-DOPO polymer, vulcanizing agent, and auxiliary cross-linking agent are mixed and vulcanized to obtain a high temperature resistant silicone rubber composition. Although the flame retardant and high temperature resistance of the silicone rubber composition are improved, the molecular structure of the related polymer is complex, resulting in increased processing difficulty and reduced processing efficiency, and the compatibility of methyl vinyl silicone rubber and isocyanurate-DOPO polymer is insufficient, resulting in unsatisfactory interface bonding performance of the material, and the aging resistance and strength under high temperature environment still cannot meet the high performance requirements. Based on the above statement, the present application proposes a high temperature resistant silicone rubber composition and its preparation process. Summary of the invention

[0004] In order to solve the problems of poor aging resistance and strength of existing silicone rubber compositions in high temperature environments, the present application provides a high temperature resistant silicone rubber composition and a preparation process thereof.

[0005] In the first aspect, the present application provides a high temperature resistant silicone rubber composition, which adopts the following technical solution:

[0006] A high temperature resistant organic silicone rubber composition comprises the following raw materials in parts by weight: 18-25 parts of vinyl-terminated polydimethylsiloxane, 10-20 parts of methylcyclosiloxane, 5-10 parts of N-vinyl pyrrolidone, 5-10 parts of functional monomers, 24-30 parts of phosphorus-nitrogen-containing copolymers, 1-3 parts of crosslinking agents, and 1-2 parts of accelerators.

[0007] Preferably, the functional monomer is obtained by mixing methylphenyl silicone oil, amino-terminated polydimethylsiloxane and styrene in a mass ratio of 7-9:3-5:1.

[0008] Preferably, the phosphorus-nitrogen-containing copolymer is prepared by the following method:

[0009] Silicon dioxide and talcum powder are mixed and ground, and then sieved to obtain a mixed powder. After adding silane coupling agent hydrolyzate and ultrasonically dispersing, triethyl phosphate and triethylenetetramine are added and stirred to mix evenly, phosphoric acid is added to adjust the pH value to 2.7-3.2, and the mixture is heated to 80-120°C while stirring. After keeping the temperature for reaction for 2-4 hours, the mixture is cooled and dried to obtain the desired phosphorus-nitrogen-containing copolymer.

[0010] Preferably, the mass ratio of silicon dioxide to talc is 4-5:1, and the mixed mixture is ground and passed through a 300-350 mesh sieve.

[0011] Preferably, the silane coupling agent hydrolyzate is prepared by the following method:

[0012] γ-aminopropyltriethoxysilane, vinylmethyldiethoxysilane and 75-85 wt % ethanol solution are mixed and stirred at 50-70° C. for 1-2 hours to obtain a silane coupling agent hydrolyzate.

[0013] Preferably, the mass ratio of the γ-aminopropyltriethoxysilane, vinylmethyldiethoxysilane and ethanol solution is 2-5:1:60.

[0014] Preferably, the mass ratio of the mixed powder, hydrolyzed silane coupling agent, triethyl phosphate and triethylenetetramine is 8-10:40-50:3-5:1-2.

[0015] Preferably, the ultrasonic power is 300-400 W, the ultrasonic frequency is 28-35 kHz, and the ultrasonic time is 1-2 h.

[0016] Preferably, the crosslinking agent is vinyltriethoxysilane; and the accelerator comprises benzoyl peroxide and zinc oxide in a mass ratio of 2-3:1.

[0017] Preferably, the high temperature resistant silicone rubber composition comprises the following raw materials in parts by weight: 22 parts of vinyl-terminated polydimethylsiloxane, 15 parts of methylcyclosiloxane, 8 parts of N-vinylpyrrolidone, 8 parts of functional monomer, 27 parts of phosphorus-nitrogen-containing copolymer, 2 parts of cross-linking agent, and 1.5 parts of accelerator.

[0018] In a second aspect, the present application provides a preparation process of a high temperature resistant silicone rubber composition, which adopts the following technical solution:

[0019] A preparation process of a high temperature resistant silicone rubber composition comprises the following steps:

[0020] S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use;

[0021] S2, premixing vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone, adding functional monomers and phosphorus-nitrogen-containing copolymers, and continuing to mix uniformly to obtain a mixture;

[0022] S3. Heat the mixture to 80-120°C, keep it warm for 2-4 hours for polymerization reaction, add a crosslinking agent and an accelerator, mix them evenly, inject them into a mold for curing and molding, and obtain a high temperature resistant silicone rubber composition.

[0023] In summary, this application has the following beneficial effects:

[0024] The present application uses terminal vinyl polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomers, phosphorus-nitrogen copolymers, crosslinking agents, and accelerators as raw materials to prepare an organic silicone rubber composition, and strictly controls the content of each component to promote the interaction between the components, which not only significantly enhances the flame retardant and high temperature resistance of the organic silicone rubber composition, but also helps to improve the aging resistance and mechanical strength of the organic silicone rubber composition in a high temperature environment. The obtained organic silicone rubber composition can adapt to high temperature harsh environment and has broad market prospects.

[0025] The present application adopts terminal vinyl polydimethylsiloxane and methylcyclosiloxane as the main matrix materials of silicone rubber. The obtained silicone material not only has low thermal conductivity and low expansion coefficient, but also can maintain the dimensional stability of the material under high temperature conditions; the silicon-oxygen bonds and carbon-silicon bonds contained therein also have high binding energy, can maintain chemical stability at high temperatures, and are not prone to decomposition, carbonization or volatilization, making the material not easily corroded by oxidants, and can obtain high temperature resistance while giving the material excellent aging resistance.

[0026] The present application adds a homemade phosphorus-nitrogen copolymer as a functional filler. On the one hand, triethyl phosphate and triethylenetetramine are added to the phosphorus-nitrogen copolymer during the preparation process, which can significantly improve the flame retardant properties of the silicone rubber. The phosphorus element can be oxidized to phosphate at high temperature and generate a carbonized layer, which plays a role in isolating the combustion source and preventing the spread of flames. The nitrogen element can dilute the combustion gas and inhibit the combustion reaction. In addition, the carbonized layer of the phosphorus-nitrogen copolymer can also absorb the heat released by combustion and reduce the combustion rate of the material. On the other hand, the phosphorus element of the phosphorus-nitrogen copolymer can stabilize the molecular structure of the silicone material, making it have antioxidant and UV resistance, delaying the aging process of the material, and further improving the aging resistance of the material.

[0027] The vinyl-terminated polydimethylsiloxane and methylcyclosiloxane in the silicone rubber composition of the present application have good elasticity and flexibility, and can provide good mechanical strength and tensile resistance. At the same time, the added functional monomers methylphenyl silicone oil, amino-terminated polydimethylsiloxane and styrene can enhance the degree of crosslinking of the material under the action of a crosslinking agent, thereby improving the hardness and wear resistance of the material. DETAILED DESCRIPTION

[0028] The present application is further described in detail below in conjunction with embodiments.

[0029] Unless otherwise specified, the experimental methods used in the examples of this application are all conventional methods.

[0030] Unless otherwise specified, the materials, reagents, etc. used in the examples of this application can be obtained from commercial sources.

[0031] Preparation Examples 1-3 and Comparative Preparation Examples 1-2 provide methods for preparing phosphorus-nitrogen-containing copolymers.

[0032] Preparation Example 1

[0033] The phosphorus-nitrogen-containing copolymer is prepared by the following method:

[0034] γ-aminopropyltriethoxysilane, vinylmethyldiethoxysilane and 75wt% ethanol solution were mixed in a mass ratio of 2:1:60, and stirred at 50°C for 2h to obtain a silane coupling agent hydrolyzate;

[0035] Silicon dioxide and talcum powder were mixed and ground in a mass ratio of 4:1, and then sieved through a 350-mesh sieve to obtain a mixed powder. After adding silane coupling agent hydrolyzate, ultrasonic dispersion was performed for 1 hour. The ultrasonic power was 400 W and the ultrasonic frequency was 35 kHz. After the ultrasonic dispersion was completed, triethyl phosphate and triethylenetetramine were added and stirred at a speed of 300 r / min for 40 minutes until the mixture was uniformly mixed. Phosphoric acid was added to adjust the pH value to 2.7, and the mixture was heated to 80°C while stirring. After the reaction was kept warm for 4 hours, it was dried at 60°C to obtain the desired phosphorus-nitrogen-containing copolymer. The mass ratio of the mixed powder, silane coupling agent hydrolyzate, triethyl phosphate and triethylenetetramine was 8:40:3:1.

[0036] Preparation Example 2

[0037] The phosphorus-nitrogen-containing copolymer is prepared by the following method:

[0038] γ-aminopropyltriethoxysilane, vinylmethyldiethoxysilane and 80wt% ethanol solution were mixed in a mass ratio of 3.5:1:60, and stirred at 60°C for 1.5h to obtain a silane coupling agent hydrolyzate;

[0039] Silicon dioxide and talcum powder were mixed and ground in a mass ratio of 4.5:1, and then sieved through a 325-mesh sieve to obtain a mixed powder. After adding silane coupling agent hydrolyzate, ultrasonic dispersion was performed for 1.5 hours, with an ultrasonic power of 350 W and an ultrasonic frequency of 32 kHz. After the ultrasonic dispersion was completed, triethyl phosphate and triethylenetetramine were added and stirred at a speed of 400 r / min for 30 minutes until the mixture was uniformly mixed. Phosphoric acid was added to adjust the pH value to 3.0, and the mixture was heated to 100°C while stirring. After the reaction was kept warm for 3 hours, it was dried at 70°C to obtain the desired phosphorus-nitrogen-containing copolymer. The mass ratio of the mixed powder, silane coupling agent hydrolyzate, triethyl phosphate and triethylenetetramine was 9:45:4:1.5.

[0040] Preparation Example 3

[0041] The phosphorus-nitrogen-containing copolymer is prepared by the following method:

[0042] γ-aminopropyltriethoxysilane, vinylmethyldiethoxysilane and 85wt% ethanol solution were mixed in a mass ratio of 5:1:60, and stirred at 70°C for 1 hour to obtain a silane coupling agent hydrolyzate;

[0043] Silicon dioxide and talcum powder were mixed and ground in a mass ratio of 5:1, and then sieved through a 300-mesh sieve to obtain a mixed powder. After adding silane coupling agent hydrolyzate, ultrasonic dispersion was performed for 2 hours, with an ultrasonic power of 300 W and an ultrasonic frequency of 28 kHz. After the ultrasonic dispersion was completed, triethyl phosphate and triethylenetetramine were added and stirred at a speed of 500 r / min for 20 minutes until the mixture was uniformly mixed. Phosphoric acid was added to adjust the pH value to 3.2, and the mixture was heated to 120°C while stirring. After the reaction was kept warm for 2 hours, the mixture was dried at 80°C to obtain the desired phosphorus-nitrogen-containing copolymer. The mass ratio of the mixed powder, silane coupling agent hydrolyzate, triethyl phosphate and triethylenetetramine was 10:50:5:2.

[0044] Comparative Preparation Example 1

[0045] The phosphorus-nitrogen-containing copolymer is prepared by the following method:

[0046] γ-aminopropyltriethoxysilane and 75wt% ethanol solution were mixed at a mass ratio of 3:60, and stirred at 50°C for 2h to obtain a silane coupling agent hydrolyzate;

[0047] Silicon dioxide and talcum powder were mixed and ground in a mass ratio of 4:1, and then sieved through a 350-mesh sieve to obtain a mixed powder. After adding silane coupling agent hydrolyzate, ultrasonic dispersion was performed for 1 hour. The ultrasonic power was 400 W and the ultrasonic frequency was 35 kHz. After the ultrasonic dispersion was completed, triethyl phosphate and triethylenetetramine were added and stirred at a speed of 300 r / min for 40 minutes until the mixture was uniformly mixed. Phosphoric acid was added to adjust the pH value to 2.7, and the mixture was heated to 80°C while stirring. After the reaction was kept warm for 4 hours, it was dried at 60°C to obtain the desired phosphorus-nitrogen-containing copolymer. The mass ratio of the mixed powder, silane coupling agent hydrolyzate, triethyl phosphate and triethylenetetramine was 8:40:3:1.

[0048] Comparative Preparation Example 2

[0049] The phosphorus-nitrogen-containing copolymer is prepared by the following method:

[0050] γ-aminopropyltriethoxysilane, vinylmethyldiethoxysilane and 75wt% ethanol solution were mixed in a mass ratio of 2:1:60, and stirred at 50°C for 2h to obtain a silane coupling agent hydrolyzate;

[0051] The silica was ground and passed through a 350-mesh sieve to obtain silica powder, and the silane coupling agent hydrolyzate was added for ultrasonic dispersion for 1 hour, with an ultrasonic power of 400 W and an ultrasonic frequency of 35 kHz. After the ultrasonic dispersion was completed, triethyl phosphate and triethylenetetramine were added and stirred at a speed of 300 r / min for 40 minutes until the mixture was uniformly mixed, and phosphoric acid was added to adjust the pH value to 2.7. The mixture was heated to 80°C while stirring, and the reaction was kept warm for 4 hours, and then dried at 60°C to obtain the desired phosphorus-nitrogen-containing copolymer; wherein the mass ratio of silica powder, silane coupling agent hydrolyzate, triethyl phosphate and triethylenetetramine was 8:40:3:1.

[0052] Embodiment 1-3 provides a high temperature resistant silicone rubber composition and a preparation process thereof.

[0053] Example 1

[0054] A high temperature resistant silicone rubber composition, comprising the following raw materials in parts by weight: 18 parts of vinyl-terminated polydimethylsiloxane, 10 parts of methylcyclosiloxane, 5 parts of N-vinyl pyrrolidone, 5 parts of functional monomers, 24 parts of phosphorus-nitrogen-containing copolymers, 1 part of crosslinking agents, and 1 part of accelerators;

[0055] The functional monomer is obtained by mixing methylphenyl silicone oil (CAS No.: 63148-58-3), amino-terminated polydimethylsiloxane (CAS No.: 97917-34-5) and styrene (CAS No.: 100-42-5) in a mass ratio of 7:3:1; the phosphorus-nitrogen-containing copolymer is prepared by Preparation Example 1; the cross-linking agent is vinyl triethoxysilane; and the accelerator includes benzoyl peroxide and zinc oxide in a mass ratio of 2:1.

[0056] A preparation process of a high temperature resistant silicone rubber composition comprises the following steps:

[0057] S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use;

[0058] S2, setting the speed to 80r / min, premixing the vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone for 20 minutes, adding the functional monomer and the phosphorus-nitrogen-containing copolymer, and continuing to mix for 20 minutes until a uniform mixture is obtained;

[0059] S3. Heat the mixture to 80°C, keep it warm and polymerize for 4 hours, then add a crosslinking agent and an accelerator, control the mixing pressure to 4MPa, the mixing temperature to 140°C, the mixing speed to 80r / min, mix for 12 minutes until it is uniform, inject it into the mold, control the vulcanization pressure to 12MPa, the vulcanization temperature to 160°C, the vulcanization time to 50min, and cure it to obtain a high temperature resistant silicone rubber composition.

[0060] Example 2

[0061] A high temperature resistant silicone rubber composition, comprising the following raw materials in parts by weight: 22 parts of vinyl-terminated polydimethylsiloxane, 15 parts of methylcyclosiloxane, 8 parts of N-vinyl pyrrolidone, 8 parts of functional monomer, 27 parts of phosphorus-nitrogen-containing copolymer, 2 parts of crosslinking agent, and 1.5 parts of accelerator;

[0062] The functional monomer is obtained by mixing methylphenyl silicone oil (CAS No.: 63148-58-3), amino-terminated polydimethylsiloxane (CAS No.: 97917-34-5) and styrene (CAS No.: 100-42-5) in a mass ratio of 8:4:1; the phosphorus-nitrogen-containing copolymer is prepared by Preparation Example 2; the cross-linking agent is vinyl triethoxysilane; and the accelerator includes benzoyl peroxide and zinc oxide in a mass ratio of 2.5:1.

[0063] A preparation process of a high temperature resistant silicone rubber composition comprises the following steps:

[0064] S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use;

[0065] S2, setting the speed to 90r / min, premixing the vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone for 15 minutes, adding the functional monomer and the phosphorus-nitrogen-containing copolymer, and continuing to mix for 15 minutes until a uniform mixture is obtained;

[0066] S3. Heat the mixture to 100°C, keep it warm and polymerize for 3 hours, then add a crosslinking agent and an accelerator, control the mixing pressure to 5MPa, the mixing temperature to 150°C, the mixing speed to 90r / min, mix for 10 minutes until it is uniform, inject it into the mold, control the vulcanization pressure to 14MPa, the vulcanization temperature to 180°C, the vulcanization time to 40min, and cure it to obtain a high temperature resistant silicone rubber composition.

[0067] Example 3

[0068] A high temperature resistant silicone rubber composition, comprising the following raw materials in parts by weight: 25 parts of vinyl-terminated polydimethylsiloxane, 20 parts of methylcyclosiloxane, 10 parts of N-vinyl pyrrolidone, 10 parts of functional monomer, 30 parts of phosphorus-nitrogen-containing copolymer, 3 parts of crosslinking agent, and 2 parts of accelerator;

[0069] The functional monomer is obtained by mixing methylphenyl silicone oil (CAS No.: 63148-58-3), amino-terminated polydimethylsiloxane (CAS No.: 97917-34-5) and styrene (CAS No.: 100-42-5) in a mass ratio of 9:5:1; the phosphorus-nitrogen-containing copolymer is prepared by Preparation Example 3; the cross-linking agent is vinyl triethoxysilane; and the accelerator includes benzoyl peroxide and zinc oxide in a mass ratio of 3:1.

[0070] A preparation process of a high temperature resistant silicone rubber composition comprises the following steps:

[0071] S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use;

[0072] S2, setting the speed to 100 r / min, premixing the vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone for 10 minutes, adding the functional monomer and the phosphorus-nitrogen-containing copolymer, and continuing to mix for 10 minutes until a uniform mixture is obtained;

[0073] S3. Heat the mixture to 120°C, keep it warm and polymerize for 2 hours, then add a crosslinking agent and an accelerator, control the mixing pressure to 6MPa, the mixing temperature to 160°C, the mixing speed to 100r / min, mix for 8 minutes until it is uniform, inject it into the mold, control the vulcanization pressure to 16MPa, the vulcanization temperature to 200°C, the vulcanization time to 30min, and cure it to obtain a high temperature resistant silicone rubber composition.

[0074] In order to verify the comprehensive performance of the high temperature resistant silicone rubber composition prepared in Examples 1-3 of the present application, the applicant set up Comparative Examples 1-5, which are as follows:

[0075] Comparative Example 1

[0076] A high temperature resistant silicone rubber composition, comprising the following raw materials in parts by weight: 18 parts of vinyl-terminated polydimethylsiloxane, 10 parts of methylcyclosiloxane, 5 parts of N-vinyl pyrrolidone, 5 parts of functional monomers, 24 parts of phosphorus-nitrogen-containing copolymers, 1 part of crosslinking agents, and 1 part of accelerators;

[0077] The functional monomer is obtained by mixing methylphenyl silicone oil (CAS No.: 63148-58-3), amino-terminated polydimethylsiloxane (CAS No.: 97917-34-5) and styrene (CAS No.: 100-42-5) in a mass ratio of 7:3:1; the phosphorus-nitrogen-containing copolymer is prepared by comparative preparation example 1; the cross-linking agent is vinyl triethoxysilane; and the accelerator includes benzoyl peroxide and zinc oxide in a mass ratio of 2:1.

[0078] A preparation process of a high temperature resistant silicone rubber composition comprises the following steps:

[0079] S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use;

[0080] S2, setting the speed to 80r / min, premixing the vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone for 20 minutes, adding the functional monomer and the phosphorus-nitrogen-containing copolymer, and continuing to mix for 20 minutes until a uniform mixture is obtained;

[0081] S3. Heat the mixture to 80°C, keep it warm and polymerize for 4 hours, then add a crosslinking agent and an accelerator, control the mixing pressure to 4MPa, the mixing temperature to 140°C, the mixing speed to 80r / min, mix for 12 minutes until it is uniform, inject it into the mold, control the vulcanization pressure to 12MPa, the vulcanization temperature to 160°C, the vulcanization time to 50min, and cure it to obtain a high temperature resistant silicone rubber composition.

[0082] Comparative Example 2

[0083] A high temperature resistant silicone rubber composition, comprising the following raw materials in parts by weight: 18 parts of vinyl-terminated polydimethylsiloxane, 10 parts of methylcyclosiloxane, 5 parts of N-vinyl pyrrolidone, 5 parts of functional monomers, 24 parts of phosphorus-nitrogen-containing copolymers, 1 part of crosslinking agents, and 1 part of accelerators;

[0084] Among them, the functional monomer is obtained by mixing methylphenyl silicone oil (CAS No.: 63148-58-3), amino-terminated polydimethylsiloxane (CAS No.: 97917-34-5) and styrene (CAS No.: 100-42-5) in a mass ratio of 7:3:1; the phosphorus-nitrogen-containing copolymer is prepared by comparative preparation example 2; the cross-linking agent is vinyl triethoxysilane; and the accelerator includes benzoyl peroxide and zinc oxide in a mass ratio of 2:1.

[0085] A preparation process of a high temperature resistant silicone rubber composition comprises the following steps:

[0086] S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use;

[0087] S2, setting the speed to 80r / min, premixing the vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone for 20 minutes, adding the functional monomer and the phosphorus-nitrogen-containing copolymer, and continuing to mix for 20 minutes until a uniform mixture is obtained;

[0088] S3. Heat the mixture to 80°C, keep it warm and polymerize for 4 hours, then add a crosslinking agent and an accelerator, control the mixing pressure to 4MPa, the mixing temperature to 140°C, the mixing speed to 80r / min, mix for 12 minutes until it is uniform, inject it into the mold, control the vulcanization pressure to 12MPa, the vulcanization temperature to 160°C, the vulcanization time to 50min, and cure it to obtain a high temperature resistant silicone rubber composition.

[0089] Comparative Example 3

[0090] A high temperature resistant silicone rubber composition, comprising the following raw materials in parts by weight: 18 parts of vinyl-terminated polydimethylsiloxane, 10 parts of methylcyclosiloxane, 5 parts of N-vinyl pyrrolidone, 5 parts of functional monomers, 24 parts of phosphorus-nitrogen-containing copolymers, 1 part of crosslinking agents, and 1 part of accelerators;

[0091] The functional monomer is obtained by mixing methylphenyl silicone oil (CAS No.: 63148-58-3) and styrene (CAS No.: 100-42-5) in a mass ratio of 10:1; the phosphorus-nitrogen-containing copolymer is prepared by Preparation Example 1; the crosslinking agent is vinyl triethoxysilane; and the accelerator includes benzoyl peroxide and zinc oxide in a mass ratio of 2:1.

[0092] A preparation process of a high temperature resistant silicone rubber composition comprises the following steps:

[0093] S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use;

[0094] S2, setting the speed to 80r / min, premixing the vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone for 20 minutes, adding the functional monomer and the phosphorus-nitrogen-containing copolymer, and continuing to mix for 20 minutes until a uniform mixture is obtained;

[0095] S3. Heat the mixture to 80°C, keep it warm and polymerize for 4 hours, then add a crosslinking agent and an accelerator, control the mixing pressure to 4MPa, the mixing temperature to 140°C, the mixing speed to 80r / min, mix for 12 minutes until it is uniform, inject it into the mold, control the vulcanization pressure to 12MPa, the vulcanization temperature to 160°C, the vulcanization time to 50min, and cure it to obtain a high temperature resistant silicone rubber composition.

[0096] Comparative Example 4

[0097] A high temperature resistant silicone rubber composition, comprising the following raw materials in parts by weight: 18 parts of vinyl-terminated polydimethylsiloxane, 10 parts of methylcyclosiloxane, 5 parts of N-vinyl pyrrolidone, 5 parts of functional monomers, 24 parts of phosphorus-nitrogen-containing copolymers, 1 part of crosslinking agents, and 1 part of accelerators;

[0098] The functional monomer is obtained by mixing amino-terminated polydimethylsiloxane (CAS No.: 97917-34-5) and styrene (CAS No.: 100-42-5) in a mass ratio of 10:1; the phosphorus-nitrogen-containing copolymer is prepared by Preparation Example 1; the cross-linking agent is vinyl triethoxysilane; and the accelerator includes benzoyl peroxide and zinc oxide in a mass ratio of 2:1.

[0099] A preparation process of a high temperature resistant silicone rubber composition comprises the following steps:

[0100] S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use;

[0101] S2, setting the speed to 80r / min, premixing the vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone for 20 minutes, adding the functional monomer and the phosphorus-nitrogen-containing copolymer, and continuing to mix for 20 minutes until a uniform mixture is obtained;

[0102] S3. Heat the mixture to 80°C, keep it warm and polymerize for 4 hours, then add a crosslinking agent and an accelerator, control the mixing pressure to 4MPa, the mixing temperature to 140°C, the mixing speed to 80r / min, mix for 12 minutes until it is uniform, inject it into the mold, control the vulcanization pressure to 12MPa, the vulcanization temperature to 160°C, the vulcanization time to 50min, and cure it to obtain a high temperature resistant silicone rubber composition.

[0103] Comparative Example 5

[0104] A high temperature resistant silicone rubber composition, comprising the following raw materials in parts by weight: 18 parts of vinyl-terminated polydimethylsiloxane, 10 parts of methylcyclosiloxane, 5 parts of N-vinyl pyrrolidone, 5 parts of functional monomers, 24 parts of phosphorus-nitrogen-containing copolymers, 1 part of crosslinking agents, and 1 part of accelerators;

[0105] The functional monomer is obtained by mixing methylphenyl silicone oil (CAS No.: 63148-58-3) and amino-terminated polydimethylsiloxane (CAS No.: 97917-34-5) in a mass ratio of 7:3; the phosphorus-nitrogen-containing copolymer is prepared by Preparation Example 1; the cross-linking agent is vinyl triethoxysilane; and the accelerator includes benzoyl peroxide and zinc oxide in a mass ratio of 2:1.

[0106] A preparation process of a high temperature resistant silicone rubber composition comprises the following steps:

[0107] S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use;

[0108] S2, setting the speed to 80r / min, premixing the vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone for 20 minutes, adding the functional monomer and the phosphorus-nitrogen-containing copolymer, and continuing to mix for 20 minutes until a uniform mixture is obtained;

[0109] S3. Heat the mixture to 80°C, keep it warm and polymerize for 4 hours, then add a crosslinking agent and an accelerator, control the mixing pressure to 4MPa, the mixing temperature to 140°C, the mixing speed to 80r / min, mix for 12 minutes until it is uniform, inject it into the mold, control the vulcanization pressure to 12MPa, the vulcanization temperature to 160°C, the vulcanization time to 50min, and cure it to obtain a high temperature resistant silicone rubber composition.

[0110] Performance Testing

[0111] The comprehensive properties of the high temperature resistant silicone rubber compositions obtained in Examples 1-3 and Comparative Examples 1-5 of the present application were tested respectively, as follows:

[0112] 1. Use an oxygen index tester to test the flame retardant properties of the silicone rubber composition according to the method of GB / T 10707-2008, and the sample size is 80mm×7mm×3mm; use a vertical combustion tester to test the vertical combustion performance, and the sample size is 100mm×12mm×3mm;

[0113] 2. Use TG thermogravimetric analyzer to analyze the thermogravimetric properties of silicone rubber composition, nitrogen atmosphere, heating rate 10℃ / min, test temperature 20-700℃;

[0114] 3. Test the tensile strength of the silicone rubber composition according to the method of GB / T 528-2009;

[0115] 4. Heat age the silicone rubber composition at 180°C for 120 hours and test the tensile strength after heat aging;

[0116] 5. Place the silicone rubber composition in an oven at 150°C for 30 minutes. The sample thickness should be greater than 6 mm. After cooling to room temperature, measure the hardness using a Shore A durometer.

[0117] The test results are shown in Table 1 below:

[0118] Table 1:

[0119]

[0120]

[0121] It can be seen from the data shown in Table 1 above that the comprehensive performance of the high temperature resistant silicone rubber composition prepared in Examples 1-3 is significantly better than that of Comparative Examples 1-5, and has obvious advantages in flame retardancy, high temperature resistance, aging resistance and mechanical strength, and has broad market prospects.

[0122] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A high temperature resistant silicone rubber composition, characterized in that: The invention comprises the following raw materials in parts by weight: 18-25 parts of vinyl-terminated polydimethylsiloxane, 10-20 parts of methylcyclosiloxane, 5-10 parts of N-vinyl pyrrolidone, 5-10 parts of functional monomer, 24-30 parts of phosphorus-nitrogen-containing copolymer, 1-3 parts of crosslinking agent and 1-2 parts of accelerator.

2. The high temperature resistant silicone rubber composition according to claim 1, characterized in that: The functional monomer is obtained by mixing methylphenyl silicone oil, amino-terminated polydimethylsiloxane and styrene in a mass ratio of 7-9:3-5:

1.

3. The high temperature resistant silicone rubber composition according to claim 1, characterized in that: The phosphorus-nitrogen-containing copolymer is prepared by the following method: Silicon dioxide and talcum powder are mixed and ground, and then sieved to obtain a mixed powder. After adding silane coupling agent hydrolyzate and ultrasonically dispersing, triethyl phosphate and triethylenetetramine are added and stirred to mix evenly, phosphoric acid is added to adjust the pH value to 2.7-3.2, and the mixture is heated to 80-120°C while stirring. After keeping the temperature for reaction for 2-4 hours, the mixture is cooled and dried to obtain the desired phosphorus-nitrogen-containing copolymer.

4. The high temperature resistant silicone rubber composition according to claim 3, characterized in that: The mass ratio of the silicon dioxide to talc is 4-5:1, and the mixture is ground and passed through a 300-350 mesh sieve.

5. The high temperature resistant silicone rubber composition according to claim 4, characterized in that: The silane coupling agent hydrolyzate is prepared by the following method: γ-aminopropyltriethoxysilane, vinylmethyldiethoxysilane and 75-85 wt % ethanol solution are mixed and stirred at 50-70° C. for 1-2 hours to obtain a silane coupling agent hydrolyzate.

6. The high temperature resistant silicone rubber composition according to claim 5, characterized in that: The mass ratio of the mixed powder, hydrolyzed silane coupling agent, triethyl phosphate and triethylenetetramine is 8-10:40-50:3-5:1-2.

7. The high temperature resistant silicone rubber composition according to claim 3, characterized in that: The ultrasonic power is 300-400W, the ultrasonic frequency is 28-35kHz, and the ultrasonic time is 1-2h.

8. The high temperature resistant silicone rubber composition according to claim 1, characterized in that: The crosslinking agent is vinyl triethoxysilane; the accelerator comprises benzoyl peroxide and zinc oxide in a mass ratio of 2-3:

1.

9. The high temperature resistant silicone rubber composition according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 22 parts of vinyl-terminated polydimethylsiloxane, 15 parts of methylcyclosiloxane, 8 parts of N-vinyl pyrrolidone, 8 parts of functional monomer, 27 parts of phosphorus-nitrogen-containing copolymer, 2 parts of crosslinking agent and 1.5 parts of accelerator.

10. A process for preparing the high temperature resistant organic silicone rubber composition according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Weigh the raw materials, vinyl-terminated polydimethylsiloxane, methylcyclosiloxane, N-vinyl pyrrolidone, functional monomer, phosphorus-nitrogen-containing copolymer, crosslinking agent and accelerator, by weight for later use; S2, premixing vinyl-terminated polydimethylsiloxane, methylcyclosiloxane and N-vinylpyrrolidone, adding functional monomers and phosphorus-nitrogen-containing copolymers, and continuing to mix uniformly to obtain a mixture; S3. Heat the mixture to 80-120°C, keep it warm for 2-4 hours for polymerization reaction, add a crosslinking agent and an accelerator, mix them evenly, inject them into a mold for curing and molding, and obtain a high temperature resistant silicone rubber composition.

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