Fluorosilicone compound rubber anti-stress relaxation agent, low stress relaxation fluorosilicone compound rubber and its preparation and application

Abstract

The present invention relates to a fluorosilicone rubber compound anti-stress relaxation agent, a low stress relaxation fluorosilicone rubber compound and its preparation and application. The anti-stress relaxation agent is butyl allyl hydroxy trifluoropropyl polysiloxane, and the low stress relaxation fluorosilicone rubber compound is composed of the following formula by weight: 100 parts of fluorosilicone raw rubber, 0.2-20 parts of dispersant, 10-80 parts of reinforcing agent, 0.2-10 parts of heat-resistant agent, 0.2-3 parts of vulcanizing agent, and 0.2-5 parts of anti-stress relaxation agent. The anti-stress relaxation agent of the present invention contains butyl allyl and allyl in the molecular structure, and the vinyl on the fluorosilicone rubber has different chain lengths of unsaturated double bonds, which can form a cross-linked network with different spatial dimensions when the rubber is cross-linked, so that the entire cross-linked network is more stable, effectively resisting the occurrence of large-scale breakage or collapse of the cross-linked network, and maintaining it for a long time, thereby reducing the speed of stress relaxation.

Description

Technical Field

[0001] The invention relates to the technical field of fluorosilicone rubber compounds, and in particular to a fluorosilicone rubber compound anti-stress relaxation agent, a low-stress relaxation fluorosilicone rubber compound, and preparation and application thereof. Background Art

[0002] Fluorosilicone rubber has excellent oil resistance, can maintain a volume change rate of 20% in fuel, and has low temperature and high temperature resistance. It can be used for a long time in an environment of -60℃~250℃, so it is widely used in aerospace, shipbuilding, automobile and other fields. The specific main application parts are seals, such as O-rings, gaskets, etc. However, because fluorosilicone rubber has a rapid stress relaxation phenomenon, when used as a static seal for a long time, it will cause leakage problems in pressure-bearing seals such as seals and gaskets, thereby losing the sealing effect, which greatly limits the application scope of fluorosilicone rubber. For example, the fuel injector seal ring in the engine is used in a high-temperature oil-related environment for a long time. Its sealing effect comes from the resistance stress generated by the workpiece when it is locked. However, as time goes by, the stress will decay. When it reaches a certain level, the sealing effect will be lost, and maintenance and replacement are very troublesome, and accidents are prone to occur. Therefore, how to reduce the speed of delaying this stress decay and thus extend the service life of fluorosilicone rubber has become an urgent problem to be solved.

[0003] Chinese patent CN114196214A discloses a silicone rubber foam sealing material and a preparation method thereof, which reduces stress relaxation by simultaneously adding vinyl silicone oil and vinyl MQ silicone resin rich in a large amount of vinyl. Although the above method can improve the ability to resist stress relaxation to a certain extent, because all of its cross-linking points come from vinyls with the same bond length, it is impossible to form a cross-linking network with a layered progressive structure. Instead, it will lead to excessive concentration of cross-linking points, resulting in an effect of too much or too little, and the strength of the rubber product is too low and brittle.

[0004] Chinese patent CN110294941A discloses a silicone rubber with excellent compressive stress relaxation performance and a preparation method thereof. By adding nano-calcium carbonate and white carbon black as fillers, the compressive stress relaxation performance of silicone rubber is improved, while taking into account the tensile strength of silicone rubber and reducing production costs. However, this technology uses nano-calcium carbonate with a specific surface area of ​​40㎡ / g. The use of fillers with a low specific surface area can improve the compressive stress relaxation performance, but it will reduce the tensile strength of silicone rubber. The tensile strength is about 5MPa, which is relatively low. Secondly, due to the limitations of the silicone rubber material itself, its oil resistance is poor and it cannot be used for a long time in some high-temperature and oil-resistant environments. In summary, its application is greatly restricted and its application range is small.

[0005] At present, in rubbers with -Si-O- as the main chain, most of the methods used to reduce stress relaxation are by increasing the degree of crosslinking or using low specific surface area fillers that are conducive to dispersion. However, the existing methods of increasing the degree of crosslinking will cause the crosslinking points to be too concentrated in a small space, which will cause the rubber to become brittle and the performance to deteriorate. The low specific surface area fillers that are conducive to dispersion have fewer filler particles that can be combined with the raw rubber under the same quality conditions, so the mechanical properties are not strong, the effect is not good, and it cannot solve the problem of long-term use of rubber seals in high-temperature oil-related working conditions. In order to solve the deficiencies of the prior art, the present invention is proposed. Summary of the invention

[0006] In view of the above technical status, the inventors of the present invention have conducted a lot of research on the stress relaxation resistance of fluorosilicone rubber mixes and found that using butylallyl trifluoropropyl hydroxy polysiloxane as an anti-stress relaxation agent to prepare fluorosilicone rubber can effectively reduce the stress relaxation rate of fluorosilicone rubber. The present invention is completed based on the above findings.

[0007] Therefore, an object of the present invention is to provide a fluorosilicone rubber anti-stress relaxation agent and a preparation method thereof, wherein the anti-stress relaxation agent can effectively reduce the stress relaxation rate of fluorosilicone rubber.

[0008] The second object of the present invention is to provide the use of butyl allyl trifluoropropyl hydroxy polysiloxane as an anti-stress relaxation agent for fluorosilicone rubber. The trifluoropropyl contained in butyl allyl trifluoropropyl hydroxy polysiloxane can promote fusion with fluorosilicone rubber while having good oil resistance. At the same time, the butyl allyl (-CH2CH2CH=CH2) and allyl (-CH2CH=CH2) on the anti-stress relaxation agent can form a cross-linked network of different chain lengths with the vinyl (-CH=CH2) on the fluorosilicone rubber, thus forming a three-dimensional cross-linked network composed of multiple chain lengths, which can effectively prevent the breakage and collapse of the cross-linked network, and at the same time effectively avoid the problem of performance degradation caused by excessively dense cross-linking points beyond a certain range when the cross-linked network is formed entirely by the opening of bonds of vinyls with shorter chain lengths.

[0009] The third object of the present invention is to provide a low stress relaxation fluorosilicone rubber compound and a preparation method thereof. By adding the anti-stress relaxation agent of the present invention, the stress relaxation rate of the prepared fluorosilicone rubber compound is greatly slowed down, and the performance of the fluorosilicone rubber compound will not be reduced due to too dense cross-linking points.

[0010] A fourth object of the present invention is to provide a use of a low stress relaxation fluorosilicone rubber compound in the field of preparing seals and the like.

[0011] The technical solution for achieving the above-mentioned invention object can be summarized as follows:

[0012] An anti-stress relaxation agent for fluorosilicone rubber compound, wherein the anti-stress relaxation agent is butylallylhydroxytrifluoropropyl polysiloxane; preferably, the polysiloxane has a structure shown in formula (I):

[0013]

[0014] In formula (I), n represents the average degree of polymerization, and 1≤n≤1500.

[0015] According to the present invention, preferably, the dynamic viscosity of the anti-stress relaxation agent at 25°C is 300 to 5000 cp, and more preferably 300 to 2000 cp;

[0016] According to the present invention, the allyl butyl allyl hydroxy trifluoropropyl polysiloxane having the structure represented by the above formula (I) is used as an anti-stress relaxation agent for fluorosilicone rubber compound.

[0017] According to the present invention, the method for preparing the above-mentioned anti-stress relaxation agent for fluorosilicone rubber compound comprises the following steps:

[0018] (1) using halobutylene and magnesium powder as raw materials to prepare butylene Grignard reagent; and then using butylene Grignard reagent and trifluoropropyltrichlorosilane as raw materials to prepare butylene trifluoropropyl dichlorosilane;

[0019] (2) using halogenated propylene and magnesium powder as raw materials to prepare an allyl Grignard reagent; and then using the allyl Grignard reagent and trifluoropropyltrichlorosilane as raw materials to prepare allyl trifluoropropyl dichlorosilane;

[0020] (3) Using butyltrifluoropropyldichlorosilane and allyltrifluoropropyldichlorosilane as raw materials, a hydrolysis copolymerization reaction is carried out to prepare an anti-stress relaxation agent for fluorosilicone compound rubber.

[0021] According to the present invention, preferably, the process of preparing the butylene Grignard reagent in step (1) is as follows:

[0022] Mix magnesium powder, tetrahydrofuran (THF) and a promoter 1,2-dibromoethane, start stirring and dropwise add a mixture of halogenated butylene and THF to react and obtain an olefinic butyl Grignard reagent;

[0023] Preferably, the mass ratio of magnesium powder to THF is 1:(3.5-5), and the mass ratio of halobutene to THF in the mixed solution of halobutene and THF is 1:(3-5);

[0024] Preferably, the halobutene is 4-chloro-1-butene, 4-bromo-1-butene or 4-iodo-1-butene;

[0025] Preferably, the reaction time is 2 to 4 hours, and the reaction temperature is controlled at 60 to 70°C.

[0026] According to the present invention, preferably, the process for preparing butyltrifluoropropyldichlorosilane in step (1) is as follows:

[0027] The butylene Grignard reagent is added dropwise to a mixed solution of trifluoropropyltrichlorosilane and THF, refluxed, and the reaction product is distilled to obtain butylenetrifluoropropyldichlorosilane;

[0028] Preferably, the molar ratio of the butylene Grignard reagent to trifluoropropyltrichlorosilane is 1:(1.2-2);

[0029] Preferably, the mass ratio of trifluoropropyltrichlorosilane to THF is 1:(2.3-3).

[0030] According to the present invention, preferably, the process of preparing the allyl Grignard reagent in step (2) is as follows:

[0031] Mix magnesium powder, tetrahydrofuran (THF) and a promoter 1,2-dibromoethane, start stirring and dropwise add a mixture of propylene halide and THF to react to obtain an allyl Grignard reagent;

[0032] Preferably, the mass ratio of magnesium powder to THF is 1:(4-6), and the mass ratio of halogenated propylene to THF in the mixed solution of halogenated propylene and THF is 1:(2.2-3.5);

[0033] Preferably, the halogenated propene is 3-chloro-1-propene or 3-bromo-1-propene or 3-iodo-1-propene;

[0034] Preferably, the reaction time is 2 to 4 hours, and the reaction temperature is controlled at 50 to 60°C.

[0035] According to the present invention, preferably, the process for preparing allyltrifluoropropyldichlorosilane in step (2) is as follows:

[0036] Adding allyl Grignard reagent dropwise to a mixed solution of trifluoropropyltrichlorosilane and THF, stirring and refluxing the mixture, and rectifying the reaction product to obtain allyltrifluoropropyldichlorosilane;

[0037] Preferably, the molar ratio of allyl Grignard reagent to trifluoropropyltrichlorosilane is: 1:(1.5-2);

[0038] Preferably, the mass ratio of trifluoropropyltrichlorosilane to THF is 1:(5-6.5).

[0039] According to the present invention, preferably, in step (3), a mixed solution of butyltrifluoropropyldichlorosilane, allyltrifluoropropyldichlorosilane and toluene is added dropwise to a mixed solution of water and toluene to carry out a hydrolysis reaction;

[0040] Preferably, the mass ratio of allyl trifluoropropyl dichlorosilane to allyl trifluoropropyl dichlorosilane is 1:(1-1.5), the mass ratio of allyl trifluoropropyl dichlorosilane to water is 1:(3-4.5), and the mass ratio of toluene to water is 1:(5.5-6.5);

[0041] Preferably, the hydrolysis reaction time is 4 to 6 hours, and the reaction temperature is controlled at 55 to 65°C.

[0042] According to the present invention, preferably, after the hydrolysis reaction in step (3) is completed, the hydrolyzate is washed with water until the hydrolyzate is neutral;

[0043] Preferably, after distilling the toluene in the hydrolyzate, a cation exchange resin is added to carry out a catalytic equilibrium polymerization reaction; preferably, the catalytic equilibrium polymerization reaction time is 5 to 7 hours, and the reaction temperature is controlled at 35 to 45° C.;

[0044] Preferably, after the catalytic equilibrium polymerization reaction is completed, the cation exchange resin is removed and vacuum distillation is performed to obtain an anti-stress relaxation agent; further preferably, the vacuum distillation conditions are -0.095 to -0.1 MPa, the interception temperature is 105 to 108° C., and the reflux ratio is 10:1.

[0045] A low stress relaxation fluorosilicone rubber compound, comprising the anti-stress relaxation agent, comprises the following components by weight:

[0046] 100 parts of fluorosilicone raw rubber, 0.2-20 parts of dispersant, 10-80 parts of reinforcing agent, 0.2-10 parts of heat-resistant agent, 0.2-3 parts of vulcanizing agent, and 0.2-5 parts of anti-stress relaxation agent.

[0047] According to the present invention, preferably, the fluorosilicone rubber has a structure shown in formula (II):

[0048] R-(R F MeSiO) x -(R Vi MeSiO) w -R

[0049] (II)

[0050] In formula (II), the end capping R is vinyl or methyl or hydroxyl, R F is a CF3CH2CH2-chain member, R Vi It is vinyl, 1000≤x≤15000, 0≤w≤800.

[0051] According to the present invention, preferably, the dispersant is selected from at least one of the following substances: hydroxysiloxane or methylsiloxane, or silazane containing vinyl, methyl, ethoxy or methoxy.

[0052] According to the present invention, preferably, the reinforcing agent is fumed silica with a BET specific surface area of ​​100-400 m 2 / g.

[0053] According to the present invention, preferably, the heat-resistant agent is iron oxide, cerium oxide or hydroxide.

[0054] According to the present invention, preferably, the vulcanizing agent is 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane, di-tert-butyl peroxide or dicumyl peroxide.

[0055] According to the present invention, the method for preparing the low stress relaxation fluorosilicone rubber compound comprises the following steps:

[0056] (1) In a kneading machine, all the fluorosilicone raw rubber, dispersant, heat-resistant additive, anti-stress relaxation agent and 1 / 5 of the reinforcing agent are respectively added according to weight parts, and the kneading function is turned on. When the reinforcing agent is completely absorbed, 1 / 5 of the reinforcing agent is added again, and the cycle is repeated until the reinforcing agent is completely absorbed;

[0057] (2) After the reinforcing agent is fully absorbed, continue kneading, and then start heating. When the temperature reaches 160-170°C, start the vacuum, and maintain the vacuum at -0.095-0.1MPa. This process lasts for 3-4h.

[0058] After the rubber is cooled, add the vulcanizing agent on the open mill and pass it through the mill 15 to 20 times to obtain a low stress relaxation fluorosilicone compound rubber.

[0059] According to the present invention, the low stress relaxation fluorosilicone rubber compound is used in the preparation of sealing components.

[0060] The technical features and beneficial effects of the present invention are as follows:

[0061] 1. The present invention connects butylene and trifluoropropyl to the same silicon atom through a Grignard reaction, and also connects allyl and trifluoropropyl to the same atom, and then forms an anti-stress relaxation agent containing butylene, allyl and trifluoropropyl structures simultaneously through cationic catalysis copolymerization. Because the structure contains unsaturated olefins of different chain lengths, the steric hindrance of unsaturated olefins during bond breaking and crosslinking can be reduced, thereby obtaining more crosslinking points, and forming a spatial crosslinking network of different chain lengths, thereby enhancing resistance to external stress.

[0062] 2. The anti-stress relaxation agent of the present invention contains the same trifluoropropyl group as fluorosilicone rubber in its molecular structure, which increases compatibility while ensuring oil resistance.

[0063] 3. The anti-stress relaxation agent of the present invention is used in very small amounts and will not cause cost pressure. At the same time, the addition process is also directly added as an auxiliary agent during the mixing process, without adding additional steps and having no effect on production efficiency.

[0064] 4. The fluorosilicone rubber of the present invention can not only slow down the rate of stress relaxation, but also avoid the problem of performance degradation due to overly dense cross-linking points. It has good tensile strength and elongation, and can be used in some high-demand aerospace fields and industrial and mining machinery under harsh conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 This is the H-NMR spectrum of the anti-stress relaxation agent prepared in Example 1. DETAILED DESCRIPTION

[0066] In the present invention, butylallyl trifluoropropyl hydroxy polysiloxane is used as an anti-stress relaxation agent to prepare fluorosilicone rubber, which can effectively reduce the stress relaxation rate of the fluorosilicone rubber.

[0067] The anti-stress relaxation agent for the fluorosilicone rubber compound of the present invention is butyl allyl hydroxy trifluoropropyl polysiloxane;

[0068] In one or more preferred embodiments, the polysiloxane has a structure shown in formula (I):

[0069]

[0070] In formula (I), n represents the average degree of polymerization, and 1≤n≤1500.

[0071] According to the present invention, the trifluoropropyl contained in the butyl allyl trifluoropropyl hydroxy polysiloxane can promote fusion with fluorosilicone rubber while having good oil resistance. At the same time, the butyl allyl (-CH2CH2CH=CH2) and allyl (-CH2CH=CH2) on the anti-stress relaxation agent can form a cross-linked network of different chain lengths with the vinyl (-CH=CH2) on the fluorosilicone rubber, thereby forming a three-dimensional cross-linked network composed of multiple chain lengths, which can effectively prevent the breakage and collapse of the cross-linked network, and at the same time effectively avoid the problem of performance degradation caused by excessively dense cross-linking points beyond a certain range when the cross-linked network is formed entirely by the opening of bonds of vinyls with shorter chain lengths.

[0072] In one or more preferred embodiments, the anti-stress relaxation agent has a dynamic viscosity of 300 to 5000 cp at 25°C, more preferably 800 to 3000 cp;

[0073] According to the present invention, the allyl butyl allyl hydroxy trifluoropropyl polysiloxane having the structure represented by the above formula (I) is used as an anti-stress relaxation agent for fluorosilicone rubber compound.

[0074] According to the present invention, the method for preparing the above-mentioned anti-stress relaxation agent for fluorosilicone rubber compound comprises the following steps:

[0075] (1) using halobutylene and magnesium powder as raw materials to prepare butylene Grignard reagent; and then using butylene Grignard reagent and trifluoropropyltrichlorosilane as raw materials to prepare butylene trifluoropropyl dichlorosilane;

[0076] (2) using halogenated propylene and magnesium powder as raw materials to prepare an allyl Grignard reagent; and then using the allyl Grignard reagent and trifluoropropyltrichlorosilane as raw materials to prepare allyl trifluoropropyl dichlorosilane;

[0077] (3) Using butyltrifluoropropyldichlorosilane and allyltrifluoropropyldichlorosilane as raw materials, a hydrolysis copolymerization reaction is carried out to prepare an anti-stress relaxation agent for fluorosilicone compound rubber.

[0078] According to the present invention, during the preparation of the anti-stress relaxation agent for fluorosilicone rubber compound, the experimental materials are dried and the reaction system is kept dry, otherwise water will inhibit the reaction.

[0079] In one or more preferred embodiments, the process for preparing the butylene Grignard reagent in step (1) is as follows:

[0080] Mix magnesium powder, tetrahydrofuran (THF) and a promoter 1,2-dibromoethane, start stirring and dropwise add a mixture of halogenated butylene and THF to react and obtain an olefinic butyl Grignard reagent;

[0081] Preferably, the mass ratio of magnesium powder to THF is 1:(3.5-5), and the mass ratio of halobutylene to THF in the mixed solution of halopropylene and THF is 1:(3-5);

[0082] Preferably, the halobutene is 4-chloro-1-butene, 4-bromo-1-butene or 4-iodo-1-butene;

[0083] Preferably, the reaction time is 2 to 4 hours, and the reaction temperature is controlled at 60 to 70°C.

[0084] In one or more preferred embodiments, the process for preparing butyltrifluoropropyldichlorosilane in step (1) is as follows:

[0085] The butylene Grignard reagent is added dropwise to a mixed solution of trifluoropropyltrichlorosilane and THF, refluxed, and the reaction product is distilled to obtain butylenetrifluoropropyldichlorosilane;

[0086] Preferably, the molar ratio of the butylene Grignard reagent to trifluoropropyltrichlorosilane is 1:(1.2-2);

[0087] Preferably, the mass ratio of trifluoropropyltrichlorosilane to THF is 1:(2.3-3).

[0088] In one or more preferred embodiments, the process for preparing the allyl Grignard reagent in step (2) is as follows:

[0089] Mix magnesium powder, tetrahydrofuran (THF) and a promoter 1,2-dibromoethane, start stirring and dropwise add a mixture of propylene halide and THF to react to obtain an allyl Grignard reagent;

[0090] Preferably, the mass ratio of magnesium powder to THF is 1:(4-6), and the mass ratio of halogenated propylene to THF in the mixed solution of halogenated propylene and THF is 1:(2.2-3.5);

[0091] Preferably, the halogenated propene is 3-chloro-1-propene or 3-bromo-1-propene or 3-iodo-1-propene;

[0092] Preferably, the reaction time is 2 to 4 hours, and the reaction temperature is controlled at 50 to 60°C.

[0093] In one or more preferred embodiments, the process for preparing allyltrifluoropropyldichlorosilane in step (2) is as follows:

[0094] Adding allyl Grignard reagent dropwise to a mixed solution of trifluoropropyltrichlorosilane and THF, stirring and refluxing the mixture, and rectifying the reaction product to obtain allyltrifluoropropyldichlorosilane;

[0095] Preferably, the molar ratio of allyl Grignard reagent to trifluoropropyltrichlorosilane is: 1:(1.5-2);

[0096] Preferably, the mass ratio of trifluoropropyltrichlorosilane to THF is 1:(5-6.5).

[0097] In one or more preferred embodiments, in step (3), a mixed solution of allyl trifluoropropyl dichlorosilane, allyl trifluoropropyl dichlorosilane and toluene is added dropwise to a mixed solution of water and toluene to carry out a hydrolysis reaction; preferably, the mass ratio of allyl trifluoropropyl dichlorosilane to allyl trifluoropropyl dichlorosilane is 1:(1-1.5), the mass ratio of allyl trifluoropropyl dichlorosilane to water is 1:(3-4.5), and the mass ratio of toluene to water is 1:(5.5-6.5);

[0098] Preferably, the hydrolysis reaction time is 4 to 6 hours, and the reaction temperature is controlled at 55 to 65°C.

[0099] In one or more preferred embodiments, after the hydrolysis reaction in step (3) is completed, the hydrolyzate is washed with water until the hydrolyzate is neutral;

[0100] Preferably, after distilling the toluene in the hydrolyzate, a cation exchange resin is added to carry out a catalytic equilibrium polymerization reaction; preferably, the catalytic equilibrium polymerization reaction time is 5 to 7 hours, and the reaction temperature is controlled at 35 to 45° C.;

[0101] Preferably, after the catalytic equilibrium polymerization reaction is completed, the cation exchange resin is removed and vacuum distillation is performed to obtain an anti-stress relaxation agent; preferably, the vacuum distillation conditions are -0.095 to -0.1 MPa, the interception temperature is 105 to 108°C, and the reflux ratio is 10:1.

[0102] According to the present invention, there is also provided a low stress relaxation fluorosilicone rubber compound, comprising the anti-stress relaxation agent, and comprising the following components in parts by weight:

[0103] 100 parts of fluorosilicone raw rubber, 0.2-20 parts of dispersant, 10-80 parts of reinforcing agent, 0.2-10 parts of heat-resistant agent, 0.2-3 parts of vulcanizing agent, and 0.2-5 parts of anti-stress relaxation agent.

[0104] In one or more preferred embodiments, the fluorosilicone rubber has a structure shown in formula (II):

[0105] R-(R F MeSiO) x -(R Vi MeSiO) w -R

[0106] (II)

[0107] In formula (II), the end capping R is vinyl or methyl or hydroxyl, R F is a CF3CH2CH2-chain member, R Vi It is vinyl, 1000≤x≤15000, 0≤w≤800.

[0108] According to the present invention, the addition of the dispersant can make the white carbon black better integrated and dispersed into the fluorosilicone rubber system, thereby preventing the generation of structuring.

[0109] In one or more preferred embodiments, the dispersant is selected from at least one of the following substances: hydroxysiloxane or methylsiloxane, or silazane containing vinyl, methyl, ethoxy or methoxy groups.

[0110] According to the present invention, the addition of the reinforcing agent can make the fluorosilicone rubber have higher performance strength, and the water content of the reinforcing agent is ≤2%.

[0111] In one or more preferred embodiments, the reinforcing agent is fumed silica with a BET specific surface area of ​​100-400 m 2 / g.

[0112] According to the present invention, the addition of a heat-resistant agent can enable the fluorosilicone rubber to be used for a long time under higher temperature conditions, and a metal oxide or hydroxide is selected.

[0113] In one or more preferred embodiments, the heat-resistant agent is iron oxide, cerium oxide or hydroxide.

[0114] According to the present invention, the addition of the vulcanizing agent can cause the double bonds on the fluorosilicone rubber to open and crosslink under the action of free radicals.

[0115] In one or more preferred embodiments, the vulcanizing agent is 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane, di-tert-butyl peroxide or dicumyl peroxide.

[0116] According to the present invention, the method for preparing the low stress relaxation fluorosilicone rubber compound comprises the following steps:

[0117] (1) In a kneading machine, all the fluorosilicone raw rubber, dispersant, heat-resistant additive, anti-stress relaxation agent and 1 / 5 of the reinforcing agent are respectively added according to weight parts, and the kneading function is turned on. When the reinforcing agent is completely absorbed, 1 / 5 of the reinforcing agent is added again, and the cycle is repeated until the reinforcing agent is completely absorbed;

[0118] (2) After the reinforcing agent is fully absorbed, continue kneading, and then start heating. When the temperature reaches 160-170°C, start the vacuum, and maintain the vacuum at -0.095-0.1MPa. This process lasts for 3-4h.

[0119] After the rubber is cooled, add the vulcanizing agent on the open mill and pass it through the mill 15 to 20 times to obtain a low stress relaxation fluorosilicone compound rubber.

[0120] According to the present invention, the low stress relaxation fluorosilicone rubber compound is used in the preparation of sealing components.

[0121] The synthetic route of the anti-stress relaxation agent for fluorosilicone rubber compound of the present invention is as follows: (1)

[0123] H2C=HC-CH2-CH2-X+Mg→H2C=CH-CH2-CH2-MgX (2)

[0125] (3)

[0127] H2C=CH-CH2-X+Mg→H2C=CH-CH2-MgX (4)

[0129] (5)

[0131]

[0132] To facilitate understanding and explanation of the present invention, some specific embodiments are provided below for illustration, but the present invention is not limited to the following embodiments.

[0133] Example 1

[0134] The preparation of 1# anti-stress relaxation agent comprises the following steps:

[0135] (1) Dry the entire reaction system to remove moisture, add 280 g of magnesium powder and 5 g of promoter 1,2-dibromoethane to 1200 ml of THF, start stirring, and dropwise add a mixed solution consisting of 1200 g of 4-chloro-1-butene and 4300 ml of THF. Control the reaction rate. After the reaction stops, 1370 g of butylene Grignard reagent is obtained.

[0136] (2) 1370 g of butylated Grignard reagent was added dropwise to 3300 g of trifluoropropyltrichlorosilane and 9500 ml of THF, and stirring was started at the same time. Attention was paid to controlling the reaction rate and maintaining a slight boiling state. After boiling stopped, reflux reaction was carried out and distillation was performed to obtain 3805 g of butylated trifluoropropyldichlorosilane.

[0137] (3) Dry the entire reaction system to remove moisture, add 240 g of magnesium powder and 5 g of promoter 1,2-dibromoethane to 1140 ml of THF, start stirring, and dropwise add a mixed solution consisting of 1120 g of 3-chloro-1-propylene and 4130 ml of THF. Control the reaction rate. After the reaction stops, 1150 g of butyl Grignard reagent is obtained.

[0138] (4) 1150 g of allyl Grignard reagent was added dropwise to 3100 g of trifluoropropyltrichlorosilane and 8900 ml of THF, and stirring was started at the same time. Attention was paid to controlling the reaction rate and maintaining a slight boiling state. After boiling stopped, reflux reaction was carried out and distillation was performed to obtain 3402 g of allyltrifluoropropyldichlorosilane.

[0139] (5) A mixed solution of 3805 g of butyltrifluoropropyldichlorosilane, 3402 g of allyltrifluoropropyldichlorosilane and 1984 g of toluene was slowly added dropwise to a mixed solution of 11900 ml of water and 1650 g of toluene to carry out a hydrolysis reaction. The temperature was controlled at about 60° C. and the mixture was stirred continuously for 4 hours. After the reaction was completed, the mixture was washed with water to remove acid until it was neutral and the toluene solution was evaporated to obtain 7152 g of a co-hydrolyzed prepolymer.

[0140] (6) Add 50 g of activated cation exchange resin to the above co-hydrolyzed prepolymer, heat slowly, control the material temperature at 40° C., and carry out catalytic equilibrium polymerization for 6 hours.

[0141] (7) The material after the catalytic equilibrium polymerization was subjected to vacuum distillation at -0.096 MPa with a reflux ratio of 10:1, and the product at 105-108° C. was cut to obtain 4325 g of butylallyl trifluoropropyl hydroxy polysiloxane.

[0142] The NMR spectrum of the product is Figure 1 As shown. In the spectrum, 0.64ppm is the chemical shift of hydrogen in -CH2- connected to silicon in the butyl group, 0.85ppm is the chemical shift of hydrogen in -CH2- connected to silicon in the trifluoropropyl group, 1.53ppm is the chemical shift of hydrogen in -CH2- connected to silicon in the allyl group, 2.09ppm is the chemical shift of hydrogen in the middle -CH2- in the trifluoropropyl group and hydrogen in -CH2- connected to the carbon-carbon double bond in the butyl group, and 4.84-5.93ppm is the chemical shift of hydrogen on the carbon-carbon double bond. The synthesized compound characterized by nuclear magnetic resonance spectrum is butyl butyl trifluoropropyl hydroxysiloxane, having the structure shown in formula (I):

[0143]

[0144] The average degree of polymerization in formula (I) is 45. The dynamic viscosity of the anti-stress relaxation agent prepared in this embodiment at 25° C. is 500 cp.

[0145] Example 2

[0146] The preparation steps of 2# anti-stress relaxation agent are the same as those of Example 1, except that:

[0147] The anti-stress relaxation agent prepared in this example has an average degree of polymerization of 54 and a dynamic viscosity of 600 cp at 25°C.

[0148] Example 3

[0149] The preparation steps of 3# anti-stress relaxation agent are the same as those of Example 1, except that:

[0150] The anti-stress relaxation agent prepared in this example has an average degree of polymerization of 73 and a dynamic viscosity of 800 cp at 25°C.

[0151] The anti-stress relaxation agent added in the following Examples 4-8 all refers to the anti-stress relaxation agent prepared in Example 1.

[0152] Example 4

[0153] Add 100 parts of fluorosilicone rubber with a vinyl content of 0.3% to the kneader, add 9.5 parts of hydroxy fluorosilicone oil, 0.5 parts of tetramethyl divinyl disilazane, 40 parts of white carbon black, 0.6 parts of cerium hydroxide, and 1 part of anti-stress relaxation agent in batches, and after mixing and eating powder, heat up to 165°C and keep it at -0.096MPa vacuum for 4 hours. After the heat treatment is completed, cool to room temperature, add 1 part of 2,5-dimethyl-2,5-diperoxy tert-butyl hexane vulcanizer on the open mill, pass it through the open mill 18 times, and take off the sheet. Hot vulcanize in a vulcanizer at 170°C for 15 minutes, and then vulcanize in a second stage in a 200°C oven for 4 hours. Test basic physical properties and stress relaxation.

[0154] Stress relaxation test standard: GBT 1685-2008, the specimen is type I in the cylindrical shape, the test temperature is 150°C, the test time is 168h, and the test is conducted using method A in the GBT 1685-2008 standard.

[0155] Example 5

[0156] Add 100 parts of fluorosilicone rubber with a vinyl content of 0.2% in a kneader, add 10 parts of hydroxyfluorosilicone oil, 42 parts of white carbon black, 0.6 parts of cerium hydroxide, and 0.5 parts of anti-stress relaxation agent in batches, and after mixing and eating powder, heat up to 165°C and keep it at -0.096MPa vacuum for 4 hours. After the heat treatment is completed, cool to room temperature, add 1 part of 2,5-dimethyl-2,5-diperoxy tert-butyl hexane vulcanizer on the open mill, pass it through the open mill 18 times, and take off the sheet. Hot vulcanize in a vulcanizer at 170°C for 15 minutes, and then vulcanize in a second stage in a 200°C oven for 4 hours. Test basic physical properties and stress relaxation.

[0157] Stress relaxation test standard: GBT 1685-2008, the specimen is type I in the cylindrical shape, the test temperature is 150℃, the test time is 168h, and the test is carried out using method A in the standard.

[0158] Example 6

[0159] Add 100 parts of fluorosilicone rubber with a vinyl content of 0.3% to the kneader, add 10 parts of hydroxyfluorosilicone oil, 1 part of hexamethyldisilazane, 45 parts of white carbon black, 0.6 parts of cerium hydroxide, and 1.5 parts of anti-stress relaxation agent in batches, and after mixing and eating powder, heat up to 165°C and keep it at -0.096MPa vacuum for 4 hours. After the heat treatment is completed, cool to room temperature, add 1 part of 2,5-dimethyl-2,5-diperoxy tert-butyl hexane vulcanizer on the open mill, pass it through the open mill 18 times, and take off the sheet. Hot vulcanize in a vulcanizer at 170°C for 15 minutes, and then vulcanize in a second stage in a 200°C oven for 4 hours. Test basic physical properties and stress relaxation.

[0160] Stress relaxation test standard: GBT 1685-2008, the specimen is type I in the cylindrical shape, the test temperature is 150℃, the test time is 168h, and the test is carried out using method A in the standard.

[0161] Example 7

[0162] Add 100 parts of fluorosilicone rubber with a vinyl content of 0.3% to the kneader, add 9 parts of hydroxyfluorosilicone oil, 1 part of hexamethyldisilazane, 38 parts of white carbon black, 0.6 parts of cerium hydroxide, and 1.7 parts of anti-stress relaxation agent in batches, and after mixing and eating powder, heat up to 165°C and keep it at -0.096MPa vacuum for 4 hours. After the heat treatment is completed, cool to room temperature, add 1 part of 2,5-dimethyl-2,5-diperoxy tert-butyl hexane vulcanizer on the open mill, pass it through the open mill 18 times, and take off the sheet. Hot vulcanize in a vulcanizer at 170°C for 15 minutes, and then vulcanize in a second stage in a 200°C oven for 4 hours. Test basic physical properties and stress relaxation.

[0163] Stress relaxation test standard: GBT 1685-2008, the specimen is type I in the cylindrical shape, the test temperature is 150℃, the test time is 168h, and the test is carried out using method A in the standard.

[0164] Example 8

[0165] Add 100 parts of fluorosilicone rubber with a vinyl content of 0.4% to the kneader, add 7 parts of hydroxyfluorosilicone oil, 0.4 parts of tetramethylvinyldisilazane, 35 parts of white carbon black, 0.6 parts of cerium hydroxide, and 2 parts of anti-stress relaxation agent in batches, and after mixing and eating powder, heat up to 165°C and keep it at -0.096Mpa vacuum for 4 hours. After the heat treatment is completed, cool to room temperature, add 1 part of 2,5-dimethyl-2,5-diperoxy tert-butyl hexane vulcanizer on the open mill, pass it through the open mill 18 times, and take off the sheet. Hot vulcanize in a vulcanizer at 170°C for 15 minutes, and then vulcanize in a second stage in a 200°C oven for 4 hours. Test basic physical properties and stress relaxation.

[0166] Stress relaxation test standard: GBT 1685-2008, the specimen is type I in the cylindrical shape, the test temperature is 150℃, the test time is 168h, and the test is carried out using method A in the standard.

[0167] Comparative Example 1

[0168] The difference between Comparative Example 1 and Example 4 is that the anti-stress relaxation agent is removed, and no anti-stress relaxation agent is added in Comparative Example 1. The other preparation methods are the same.

[0169] Comparative Example 2

[0170] The difference between Comparative Example 2 and Example 4 is that no anti-stress relaxation agent is added in Comparative Example 2, but OH-[(CH2CH2 CF 3 )(CH2=CHCH2CH2CH2)SiO] m 1 part of butyl-containing hydroxyl-terminated fluorosilicone oil containing -H is substituted for the anti-stress relaxation agent, and the other preparation methods are the same.

[0171] Comparative Example 3

[0172] The difference between Comparative Example 3 and Example 4 is that no anti-stress relaxation agent is added in Comparative Example 3, but OH-[(CH2CH2 CF 3 )(CH2=CHCH2)SiO] m 1 part of allyl-containing hydroxyl-terminated fluorosilicone oil containing -H is used instead of the anti-stress relaxation agent, and the other preparation methods are the same.

[0173] Comparative Example 4

[0174] The difference between Comparative Example 4 and Example 4 is that no anti-stress relaxation agent is added in Comparative Example 4, but OH-[(CH2CH2 CF 3 )(CH2=CH)SiO] m -H-containing vinyl-containing hydroxyl-terminated fluorosilicone oil 1 part instead of the anti-stress relaxation agent, the other preparation methods are the same.

[0175] Test Example 1

[0176] The test data of test examples 4-8 and comparative examples 1-4 are shown in Table 1 below:

[0177] Table 1 Test data related to embodiments and comparative examples

[0178]

[0179]

[0180] It can be clearly seen from Table 1 that the stress relaxation data of Examples 4-8 are significantly lower than those of Comparative Examples 1-3, indicating that the addition of anti-stress relaxation agents can effectively reduce stress relaxation, that is, under the same time conditions, the rate of stress relaxation is greatly slowed down.

[0181] Comparing Comparative Example 1 with Example 4, the stress relaxation of Comparative Example 1 is 16.3% higher than that of Example 4. No anti-stress relaxation agent is added in Comparative Example 1, which shows that the effect of the anti-fatigue agent is very obvious.

[0182] Compared with Example 4, Comparative Example 2 has a stress relaxation of 15.1% higher than that of Example 5. Comparative Example 2 uses hydroxy fluorosilicone oil containing only allyl groups, which cannot form an effective layer-by-layer progressive spatial network structure during cross-linking, that is, the spatial network collapses easily when resisting stress relaxation, thereby losing resistance.

[0183] Comparing Comparative Example 3 with Example 4, the stress relaxation of Comparative Example 3 is 15.3% higher than that of Example 4. Comparative Example 3 uses hydroxy fluorosilicone oil containing only allyl groups. For the same reason as Comparative Example 2, the cross-linked network containing only allyl groups cannot effectively form a layer-by-layer progressive spatial network.

[0184] Compared with Example 4, Comparative Example 4 has a stress relaxation that is 15.9% higher than that of Example 4. Comparative Example 4 uses vinyl-containing fluorosilicone oil, which also cannot form an effective progressive cross-linking network, so the stress relaxation is also very high.

[0185] The above embodiments are only partial examples and cannot fully represent the present invention. In addition, the integration and reorganization of the relevant technical features in the present invention also fall within the protection scope of the present invention.

Claims

1. An anti-stress relaxation agent for fluorosilicone rubber compound, characterized in that: The anti-stress relaxation agent is butyl allyl hydroxy trifluoropropyl polysiloxane, and the polysiloxane has a structure shown in formula (I): In formula (I), n represents the average degree of polymerization, and 1≤n≤1500.

2. The anti-stress relaxation agent for fluorosilicone rubber compound according to claim 1, characterized in that: The anti-stress relaxation The dynamic viscosity of the agent at 25°C is 300~5000cp.

3. Use of the butylallylhydroxytrifluoropropyl polysiloxane described in claim 1 as an anti-stress relaxation agent for fluorosilicone rubber compounds.

4. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 1 or 2, comprising the following steps: (1) Using halobutylene and magnesium powder as raw materials, preparing butylene Grignard reagent; and then using butylene Grignard reagent and trifluoropropyltrichlorosilane as raw materials to prepare butylene trifluoropropyl dichlorosilane; (2) using halogenated propylene and magnesium powder as raw materials to prepare allyl Grignard reagent; and then using allyl Grignard reagent and trifluoropropyltrichlorosilane as raw materials to prepare allyl trifluoropropyl dichlorosilane; (3) Using butyltrifluoropropyldichlorosilane and allyltrifluoropropyldichlorosilane as raw materials, a hydrolysis copolymerization reaction was carried out to prepare an anti-stress relaxation agent for fluorosilicone compound rubber.

5. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 4, characterized in that: The process of preparing the butylene Grignard reagent in step (1) is as follows: Mix magnesium powder, tetrahydrofuran (THF) and a promoter 1,2-dibromoethane, start stirring and drop a mixture of halogenated butylene and THF to react and obtain an olefinic butyl Grignard reagent.

6. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 5, characterized in that: The mass ratio of magnesium powder to THF is 1:(3.5~5), and the mass ratio of halobutene to THF in the mixed solution of halobutene and THF is 1:(3~5).

7. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 5, characterized in that: The halobutene is 4-chloro-1-butene, 4-bromo-1-butene or 4-iodo-1-butene; the reaction time is 2-4 hours, and the reaction temperature is controlled at 60-70°C.

8. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 4, characterized in that: The process for preparing butyltrifluoropropyldichlorosilane in step (1) is as follows: The butylene Grignard reagent is added dropwise to a mixed solution of trifluoropropyltrichlorosilane and THF, and the mixture is refluxed for reaction. The reaction product is distilled to obtain butylenetrifluoropropyldichlorosilane.

9. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 8, characterized in that: The molar ratio of the butylated Grignard reagent to trifluoropropyltrichlorosilane is 1:(1.2~2), and the mass ratio of trifluoropropyltrichlorosilane to THF is 1:(2.3~3).

10. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 4, characterized in that: The process of preparing the allyl Grignard reagent in step (2) is as follows: Mix magnesium powder, tetrahydrofuran (THF) and the promoter 1,2-dibromoethane, start stirring and dropwise add the mixture of halogenated propylene and THF to react to obtain the allyl Grignard reagent.

11. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 10, characterized in that: The mass ratio of magnesium powder to THF is 1:(4~6), and the mass ratio of halogenated propylene to THF in the mixed solution of halogenated propylene and THF is 1:(2.2~3.5).

12. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 10, characterized in that: The halogenated propene is 3-chloro-1-propene, 3-bromo-1-propene or 3-iodo-1-propene, the reaction time is 2-4 hours, and the reaction temperature is controlled at 50-60°C.

13. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 4, characterized in that: The process for preparing allyltrifluoropropyldichlorosilane in step (2) is as follows: The allyl Grignard reagent is added dropwise to a mixed solution of trifluoropropyltrichlorosilane and THF, and stirring is started at the same time. The mixture is refluxed and the reaction product is distilled to obtain allyltrifluoropropyldichlorosilane.

14. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 13, characterized in that: The molar ratio of allyl Grignard reagent to trifluoropropyltrichlorosilane is 1:(1.5~2), and the mass ratio of trifluoropropyltrichlorosilane to THF is 1:(5~6.5).

15. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 4, characterized in that: In step (3), a mixed solution of butyltrifluoropropyldichlorosilane, allyltrifluoropropyldichlorosilane and toluene is added dropwise to a mixed solution of water and toluene to carry out a hydrolysis reaction.

16. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 15, characterized in that: The mass ratio of allyl trifluoropropyl dichlorosilane to allyl trifluoropropyl dichlorosilane is 1:(1~1.5), the mass ratio of allyl trifluoropropyl dichlorosilane to water is 1:(3~4.5), and the mass ratio of toluene to water is 1:(5.5~6.5).

17. The method for preparing the anti-stress relaxation agent for fluorosilicone rubber compound according to claim 16, characterized in that: The hydrolysis reaction time is 4~6h, and the reaction temperature is controlled at 55~65℃.

18. A low stress relaxation fluorosilicone rubber compound, comprising the anti-stress relaxation agent according to claim 1 or 2, and comprising the following components in parts by weight: 100 parts of fluorosilicone rubber, 0.2-20 parts of dispersant, 10-80 parts of reinforcing agent, 0.2-10 parts of heat-resistant agent, 0.2-3 parts of vulcanizing agent, 0.2-5 parts of anti-stress relaxation agent; The fluorosilicone rubber has a structure shown in formula (II): R-(R F MeSiO)x -(R Vi MeSiO)w -R (II) In formula (II), the end capping R is vinyl, methyl or hydroxyl, R F is a CF3CH2CH2-chain member, R Vi It is vinyl, 1000≤x≤15000, 0≤w≤800.

19. The low stress relaxation fluorosilicone rubber compound according to claim 18, characterized in that: The dispersant is selected from at least one of the following substances: hydroxysiloxane or methylsiloxane, or silazane containing vinyl, methyl, ethoxy or methoxy groups; the reinforcing agent is fumed silica with a BET specific surface area of ​​100-400 m 2 / g; the heat-resistant agent is iron oxide, cerium oxide or hydroxide; the vulcanizing agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, di-tert-butyl peroxide or dicumyl peroxide.

20. The method for preparing the low stress relaxation fluorosilicone rubber compound according to claim 18, comprising the following steps: (1) In a kneading machine, add all the fluorosilicone rubber, dispersant, heat-resistant additive, anti-stress relaxation agent and 1 / 5 of the reinforcing agent according to weight, start the kneading function, and when the reinforcing agent is completely absorbed, add 1 / 5 of the reinforcing agent again, and repeat this cycle until the reinforcing agent is completely absorbed; (2) After the reinforcing agent has finished eating the powder, continue kneading and then start heating. When the temperature reaches 160~170℃, start the vacuum and maintain the vacuum at -0.095~-0.1MPa. This process lasts for 3~4h. After the rubber has cooled, add the vulcanizing agent on the open mill and pass it through the mill 15 to 20 times to obtain a low stress relaxation fluorosilicone compound rubber.

21. Use of the low stress relaxation fluorosilicone rubber compound according to claim 18 in the preparation of sealing parts.

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