A kind of high temperature vulcanized fluorosilicone rubber for bonding metal and its preparation and use method

Abstract

The present invention relates to a metal-bonded high-temperature vulcanized fluorosilicone rubber and a preparation and use method thereof, wherein the fluorosilicone rubber comprises the following components in parts by weight: 100 parts of fluorosilicone raw rubber, 20 to 60 parts of modified reinforcing fillers, 2 to 10.0 parts of tackifiers, 0.5 to 5.0 parts of heat-resistant agents, and 0.5 to 2.0 parts of cross-linking agents. The present invention adds a hydroxyl-terminated vinyl organopolysiloxane tackifier and simultaneously modifies the vinyl of the reinforcing filler, so that the fluorosilicone rubber obtains excellent bonding properties with metals during high-temperature vulcanization, and maintains excellent bonding properties for a long time in harsh oil environments, and can be better applied to rubber-metal composite components such as oil pressure system seals and pump diaphragms.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber materials, and in particular relates to a metal bonding high-temperature vulcanized fluorosilicone rubber and a preparation method thereof. Background Art

[0002] Fluorosilicone rubber is a high-performance elastomer with trifluoropropyl groups introduced on the side chains of the silicone chain. It has good oil resistance, heat resistance, weather resistance, electrical insulation, resilience, solvent resistance and saturated steam resistance. It has better high-temperature mechanical properties, cold resistance, compression permanent set and processing properties than fluororubber. Its application is increasingly valued and can be widely used in modern military industry, automobile industry, aerospace industry, petrochemical industry, machinery and other fields, and has gradually become an indispensable new polymer material in national defense and national economy.

[0003] However, since the main chain of the fluorosilicone rubber system is Si-O chain, the surface free energy is very low, the surface wettability and bonding properties are poor, and it is a surface inert elastomer. It is difficult to form effective bonding with many materials such as metals, and there are difficulties in bonding, which severely limits its use in composite materials combined with metals. Therefore, how to improve the bonding between fluorosilicone rubber and such materials has become an urgent problem to be solved.

[0004] Chinese patent document CN108219688A discloses a method for bonding silicone rubber parts to metal parts, which uses silicone rubber film to dissolve in ethyl acetate solvent to prepare silicone rubber raw slurry, and then applies it to the metal part that has been coated with adhesive, and performs co-vulcanization to achieve the bonding of silicone rubber parts to metal parts. Chinese patent document CN110128827A uses bisamide silane coupling agent or vinyl silane coupling agent as a tackifier in silicone rubber, and adds an appropriate amount of polyhydroxy-containing cross-linking agent trimethylolpropane trimethacrylate to improve the bonding strength between silicone rubber and metal. The disadvantage is that when the methods of the two patents are used for fluorosilicone rubber, the bonding and co-vulcanization are performed with metal, and the bonding effect is not ideal, and it cannot meet the bonding performance of fluorosilicone rubber and metal in a high-temperature oil environment. U.S. Patent US 4980396A uses tris(trialkoxysilyl) triisocyanate as a primer to improve the bonding performance of fluorosilicone rubber to metals, plastics and other materials, so that fluorosilicone rubber has better bonding with metals. However, due to the small force between fluorosilicone rubber, the adhesive and the metal end, the bonding between fluorosilicone rubber and metal cannot be guaranteed in harsh oil environments. Chinese patent document CN101531881A provides an adhesive for bonding fluorosilicone rubber to metal and a preparation method thereof. The adhesive comprises the following components: a fluorosilicone rubber compound, a silane coupling agent containing a peroxide group, a silane coupling agent containing an olefin functional group, a ketone solvent and an ester solvent. However, in order to avoid the chaotic reaction of the components or the excessive reaction to cause unstable product performance, the adhesive needs to be operated strictly according to a certain component mixing procedure: first, component A is prepared and mixed, and then component D and component E are mixed in a specified proportion, sealed and parked for 1 to 2 days, then unsealed, the reaction gas is released, stirred evenly, component C is mixed, sealed and parked for 1 to 2 days, then unsealed, the reaction gas is released, stirred evenly, component B is mixed, sealed and parked for 1 to 2 days, then unsealed, the reaction gas is released, stirred evenly, and the adhesive product is prepared. The process is relatively complex, the cycle is long, and there are unstable factors, which is not conducive to industrial production.

[0005] Therefore, it is of great significance to develop a fluorosilicone rubber having excellent bonding properties to metals and higher bonding strength in harsh high-temperature oil environments. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention provides a metal-bonded high-temperature vulcanized fluorosilicone rubber and a preparation and use method thereof. The metal-bonded high-temperature vulcanized fluorosilicone rubber of the present invention is added with a hydroxyl-terminated vinyl organopolysiloxane tackifier, and is reinforced with a vinyl-modified filler. During the high-temperature vulcanization process, the hydroxyl-terminated vinyl organopolysiloxane tackifier will migrate to the surface of the fluorosilicone rubber, and the vinyl groups on its chain segments can combine with a large number of vinyl groups in the vinyl-modified reinforcing filler and the vinyl in the fluorosilicone raw rubber, while the terminal hydroxyl groups with higher activity can promote the primer to form a stable combination with the hydroxyl groups on the metal surface, thereby achieving high-temperature vulcanization bonding between the fluorosilicone rubber end and the metal end. The fluorosilicone rubber-metal composite prepared by this method can still maintain excellent bonding between the fluorosilicone rubber and the metal in a high-temperature oil environment. The preparation method of the present invention is simple and easy to implement. The bonding between the fluorosilicone rubber and the metal can be achieved by coating the existing commercially available metal primer, and is suitable for application in industrial applications such as compression vulcanization and injection molding.

[0007] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0008] A metal bonding high temperature vulcanized fluorosilicone rubber, comprising the following components by weight: 100 parts of fluorosilicone raw rubber, 2 to 10 parts of tackifier, 20 to 60 parts of modified reinforcing filler, 0.5 to 5 parts of heat resistant agent, and 0.5 to 2 parts of cross-linking agent;

[0009] The tackifier is a hydroxyl-terminated vinyl organopolysiloxane tackifier.

[0010] According to the preferred embodiment of the present invention, the fluorosilicone rubber is polymethyltrifluoropropylsiloxane having the structure shown in the general formula (I):

[0011]

[0012] In the general formula (I), R1 and R2 are each independently selected from methyl, vinyl or hydroxyl, x is an integer ≥ 3000, and y is an integer from 1 to 100;

[0013] Further preferably, the molecular weight of the fluorosilicone rubber is 60×10 4 ~160×10 4 g / mol, and the vinyl content is 0.01 to 2 mol%.

[0014] Preferably, according to the present invention, the modified reinforcing filler is vinyl-modified fumed silica, and the modifier used for the vinyl-modified fumed silica is a compound containing an active group that can react with a hydroxyl group on the surface of silica and containing a vinyl group. Preferably, the modifier is one or a combination of two or more of vinyltrimethoxysilane, vinyltriethoxysilane, methylvinyldimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltri-tert-butoxysilane, vinyltriacetoxysilane, dimethylvinylchlorosilane, and methylvinyldichlorosilane.

[0015] Preferably, the modified reinforcing filler is prepared according to the following method: adding fumed silica to a mixing device, heating to a reaction temperature, dripping a modifier into the mixing device, and reacting under nitrogen protection; after the reaction is completed, heat treatment is performed to remove small molecular substances and water produced during the reaction to obtain vinyl-modified fumed silica, which is the modified reinforcing filler;

[0016] Further preferably, there is no special requirement for the BET specific surface area of ​​the fumed silica, which can be adjusted according to the basic properties of the fluorosilicone rubber. Preferably, the BET specific surface area of ​​the fumed silica is 100 to 400 m 2 / g;

[0017] Further preferably, the mass ratio of the fumed silica to the modifier is 100:(10-20);

[0018] Further preferably, the reaction temperature is 100-150° C.; the reaction time is 2-6 hours;

[0019] More preferably, the heat treatment temperature is 90-100° C., and the heat treatment is performed until constant weight.

[0020] Preferably, according to the present invention, the tackifier has a structure shown in general formula (II):

[0021]

[0022] In the general formula (II), R3 and R4 are each independently selected from a saturated hydrocarbon group or an aromatic group; p is an integer of 1 to 100, and q is an integer of 1 to 200;

[0023] Further preferably, R3 and R4 are each independently selected from methyl, ethyl, propyl, isopropyl, butyl, hexyl, 2-ethylhexyl, octyl, isooctyl, decyl or phenyl; more preferably, R3 and R4 are each independently selected from methyl, ethyl, propyl.

[0024] According to the preferred embodiment of the present invention, the kinematic viscosity of the tackifier at 25°C is 50 to 500 mm 2 / s, when the viscosity is lower than 50mm 2 / s, the viscosity enhancer easily seeps out of the surface, causing the loss of fluorosilicone rubber components and making the mixing process difficult. When the viscosity is higher than 500mm 2 / s, during the high-temperature co-vulcanization process, the tackifier is not easy to migrate to the rubber surface, and the bonding effect between fluorosilicone rubber and metal cannot be guaranteed.

[0025] Preferably according to the present invention, the vinyl content of the tackifier is 2 to 10 mol%. When it is lower than 2 mol%, the bonding effect between the fluorosilicone rubber and the metal is poor. When the vinyl content of the tackifier is higher than 10 mol%, it is easy to cause the vinyl content in the fluorosilicone rubber to be too high, resulting in an excessive degree of local cross-linking, which affects the basic mechanical properties.

[0026] Preferably according to the present invention, the heat-resistant agent is one or a combination of two or more of iron oxide, cerium oxide, tin oxide, zinc oxide, magnesium oxide and titanium dioxide.

[0027] Preferably, according to the present invention, the crosslinking agent is an organic peroxide crosslinking agent; preferably, the crosslinking agent is one or a combination of two or more of benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, diisopropylbenzene peroxide, di-tert-butyl peroxide, and 1,1-di(tert-butylperoxide)-3,3,5-trimethylcyclohexane.

[0028] The present invention also provides a method for preparing the above-mentioned metal bonding high temperature vulcanized fluorosilicone rubber, comprising the following steps:

[0029] (1) Adding fluorosilicone raw rubber to a rubber mixing device, and adding modified reinforcing fillers in 3 to 6 batches for mixing, and kneading for 0.5 h to 2 h after mixing evenly, and then performing heat treatment;

[0030] (2) Lowering the temperature of the rubber compound to below 50°C, adding a tackifier to the rubber compound and mixing until the materials are evenly mixed;

[0031] (3) controlling the temperature of the rubber compound to be below 50° C., adding a heat-resistant agent to the rubber compound and mixing the mixture until the mixture is uniform to obtain a mixed rubber;

[0032] (4) Add a crosslinking agent to the rubber mixture obtained above, mix until uniform, and obtain a high-temperature vulcanized fluorosilicone rubber for bonding metals.

[0033] Preferably, according to the present invention, the heat treatment conditions in step (1) are: carried out under nitrogen protection or vacuum conditions, the vacuum treatment needs to maintain a pressure of -0.06MPa to -0.099MPa; the heat treatment temperature is 140 to 200°C; and the heat treatment time is 2 to 6h.

[0034] According to the present invention, a method for using the above-mentioned high-temperature vulcanized fluorosilicone rubber for bonding metals is also provided, comprising the following steps:

[0035] (1) Treat the metal surface to remove oil, dust, solvent and moisture, then apply a primer on the metal surface and dry it;

[0036] (2) After the treated metal is bonded to the bonding metal high temperature vulcanized fluorosilicone rubber, high temperature vulcanization is performed to complete the metal bonding.

[0037] According to the present invention, preferably, the primer described in step (1) is a conventional commercial product, preferably Chemlock 608 primer.

[0038] According to the present invention, preferably, the high temperature vulcanization conditions in step (2) are: a first stage vulcanization at 170°C for 15 min and a second stage vulcanization at 200°C for 4 h.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] 1. The metal bonding high temperature vulcanized fluorosilicone rubber of the present invention has excellent bonding properties with metals such as steel, iron, and aluminum, has high bonding strength in harsh high temperature oil environments, and can achieve peeling cohesive failure of most contact surfaces.

[0041] 2. The tackifier in the formula of the present invention will precipitate to the surface during the high-temperature vulcanization process of the fluorosilicone rubber. Its terminal hydroxyl group has high activity and can enhance the combination of the primer and the hydroxyl group on the metal surface, thereby enhancing the bonding strength with the metal end.

[0042] 3. The vinyl-modified silica used in the formula of the present invention has a relatively high concentration of vinyl groups, which can react with the vinyl groups in the tackifier to enhance the bonding strength with the fluorosilicone rubber end.

[0043] 4. The metal-bonded high-temperature vulcanized fluorosilicone rubber provided by the present invention can achieve the bonding of fluorosilicone rubber and metal ends using existing commercially available metal primers, is suitable for compression vulcanization, injection molding vulcanization, etc., has simple operation, strong applicability, low cost, and can be applied to industrial-scale production. DETAILED DESCRIPTION

[0044] In order to better reflect the advantages of the present invention, the present invention is further described by the following specific examples, but it does not constitute any limitation to the present invention. The raw materials used in the examples are all conventional raw materials, commercial products, and the equipment used is all conventional equipment.

[0045] In Examples 1-5 and Comparative Examples 1 to 5, metal bonding high temperature vulcanized fluorosilicone rubber was prepared, and the structural formula of the fluorosilicone raw rubber used is as follows:

[0046]

[0047] Here, x is an integer ≥3000, and y is an integer from 1 to 100.

[0048] The fluorosilicone rubber in the present invention is a conventional raw material, which can be purchased from the market or prepared according to the prior art, and can be prepared by referring to the method mentioned in Chinese patent CN 103012801A "A method for preparing fluorosilicone rubber with controllable molecular weight".

[0049] The tackifier in the present invention is a hydroxyl-terminated vinyl organic polysiloxane tackifier, which can be purchased commercially or prepared according to the prior art. The preparation method can be as follows: according to the required vinyl content, cyclosiloxane and vinyl cyclosiloxane are added to a reaction kettle with stirring, heating and vacuuming, and the temperature is raised to 50° C. and dehydrated under reduced pressure for 1 hour; a tetramethylammonium hydroxide catalyst of 0.01% of the total amount of siloxane is added, and distilled water as a capping agent is added according to the viscosity requirement; the temperature is raised to 90° C. for insulation, and a balanced polymerization reaction is carried out for 2 hours under N2 protection; the temperature is raised to 150° C. for a catalyst breaking treatment for 1 hour; the temperature is continued to be raised to 180° C., and small molecular substances are removed under the condition of a vacuum degree of>-0.098MPa, and the mixture is cooled to room temperature to complete the preparation of the hydroxyl-terminated vinyl organic polysiloxane tackifier.

[0050] The structural formula of the tackifier used in Examples 1-3 is as follows:

[0051]

[0052] Here, p is an integer of 1 to 100, and q is an integer of 1 to 200.

[0053] Example 1

[0054] A high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following components by weight: 100 parts of fluorosilicone raw rubber, 35 parts of modified reinforcing filler, 8 parts of tackifier, 1 part of heat-resistant agent and 0.6 part of cross-linking agent.

[0055] The fluorosilicone rubber has a vinyl content of 0.1 mol% and a molecular weight of 84×10 4 g / mol.

[0056] The modified reinforcing filler is prepared according to the following method: 100 parts by weight of a BET specific surface area of ​​300 m2 is added to a high-speed mixer. 2 / g fumed silica, raise the temperature to 120°C, add 10 parts by weight of vinyl tri(β-methoxyethoxy)silane dropwise, the adding time is 50 min, after the adding is completed, high-speed mixing is carried out under nitrogen protection conditions, the rotation speed is 500 r / min, the reaction time is 4 h, and the obtained reactant is placed in a 100°C oven for heat treatment to constant weight to obtain the product.

[0057] The tackifier is hydroxyl-terminated methyl vinyl silicone oil, and the kinematic viscosity at 25°C is 185 mm 2 / s, vinyl content 7.6 mol%.

[0058] The heat-resistant agent is cerium oxide; the cross-linking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide

[0059] The preparation method of the above-mentioned high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following steps:

[0060] Add fluorosilicone raw rubber to a vacuum kneader, add modified reinforcing fillers in 4 batches, and knead for 1 hour; after mixing evenly, evacuate and heat treat the materials at 160°C × 2h and a pressure of -0.09MPa to -0.099MPa; cool to 50°C, add a viscosity enhancer to the materials, and mix until uniform; then add a heat-resistant agent, mix until uniform, and obtain a rubber mixture; add a cross-linking agent to the rubber mixture on an open mill, thin it, and sheet it to complete the preparation of the fluorosilicone rubber.

[0061] Example 2

[0062] A high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following components by weight: 100 parts of fluorosilicone raw rubber, 30 parts of modified reinforcing filler, 4 parts of tackifier, 2 parts of heat-resistant agent and 0.8 parts of cross-linking agent.

[0063] The fluorosilicone rubber has an ethylene content of 0.3 mol% and a molecular weight of 107×10 4 g / mol.

[0064] The modified reinforcing filler is prepared according to the following method: 100 parts by weight of a BET specific surface area of ​​200 m2 is added to a high-speed mixer. 2 / g fumed silica, raise the temperature to 120°C, add 10 parts by weight of vinyltrimethoxysilane dropwise, the adding time is 50 min, after the adding is completed, high-speed mixing is carried out under nitrogen protection conditions, the rotation speed is 500r / min, the reaction time is 4h, and the obtained reactant is placed in a 100°C oven for heat treatment to constant weight to obtain the product.

[0065] The tackifier is hydroxyl-terminated methyl vinyl silicone oil, and the kinematic viscosity at 25°C is 65 mm 2 / s, vinyl content 4.2 mol%.

[0066] The heat-resistant agent is iron oxide; and the cross-linking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide.

[0067] The preparation method of the above-mentioned high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following steps:

[0068] Add fluorosilicone raw rubber to a vacuum kneader, add modified reinforcing fillers in 3 batches, and knead for 1 hour; after mixing evenly, evacuate and heat treat the materials at 150°C × 2h and a pressure of -0.09MPa to -0.099MPa; cool to 50°C, add a viscosity enhancer to the materials, and mix until uniform; then add a heat-resistant agent, mix until uniform, and obtain a rubber mixture; add a cross-linking agent to the rubber mixture on an open mill, thin it, and sheet it to complete the preparation of the fluorosilicone rubber.

[0069] Example 3

[0070] A high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following components by weight: 100 parts of fluorosilicone raw rubber, 38 parts of modified reinforcing filler, 4 parts of tackifier, 2 parts of heat-resistant agent and 0.5 parts of cross-linking agent.

[0071] The fluorosilicone rubber has an ethylene content of 0.2 mol% and a molecular weight of 103×10 4 g / mol.

[0072] The modified reinforcing filler is prepared according to the following method: 100 parts by weight of a BET specific surface area of ​​300 m2 is added to a high-speed mixer. 2 / g fumed silica, raise the temperature to 120°C, add 15 parts by weight of dimethylvinylchlorosilane dropwise, the adding time is 50 min, after the adding is completed, high-speed mixing is carried out under nitrogen protection conditions, the rotation speed is 500r / min, the reaction time is 4h, and the obtained reactant is placed in a 100°C oven for heat treatment to constant weight to obtain the product.

[0073] The tackifier is hydroxyl-terminated methyl vinyl silicone oil, and the kinematic viscosity at 25°C is 326 mm 2 / s, vinyl content 4.3 mol%.

[0074] The heat-resistant agent is titanium dioxide; and the cross-linking agent is dicumyl peroxide.

[0075] The preparation method of the above-mentioned high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following steps:

[0076] Add fluorosilicone raw rubber to a vacuum kneader, add modified reinforcing fillers in 4 batches, and knead for 1 hour; after mixing evenly, evacuate and heat treat the materials at 150°C × 2h and a pressure of -0.09MPa to -0.099MPa; cool to 50°C, add a viscosity enhancer to the materials, and mix until uniform; then add a heat-resistant agent, mix until uniform, and obtain a rubber mixture; add a cross-linking agent to the rubber mixture on an open mill, thin it, and sheet it to complete the preparation of the fluorosilicone rubber.

[0077] The structural formula of the tackifier used in Examples 4 and 5 is as follows:

[0078]

[0079] Wherein, p is an integer from 1 to 100, and q is an integer from 1 to 200;

[0080] Example 4

[0081] A high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following components by weight: 100 parts of fluorosilicone raw rubber, 40 parts of modified reinforcing filler, 8 parts of tackifier, 1 part of heat-resistant agent and 0.6 part of cross-linking agent.

[0082] The fluorosilicone rubber has an ethylene content of 0.08 mol% and a molecular weight of 82×10 4 g / mol.

[0083] The modified reinforcing filler is prepared according to the following method: 100 parts by weight of a BET specific surface area of ​​200 m2 is added to a high-speed mixer. 2 / g fumed silica, raise the temperature to 120°C, add 12 parts by weight of vinyl tri-tert-butoxysilane dropwise, the adding time is 50 min, after the adding is completed, high-speed mixing is carried out under nitrogen protection conditions, the rotation speed is 500r / min, the reaction time is 4h, and the obtained reactant is placed in a 100°C oven for heat treatment to constant weight to obtain the product.

[0084] The tackifier is hydroxyl-terminated methyl ethyl vinyl silicone oil, and the kinematic viscosity at 25°C is 102 mm 2 / s, vinyl content 4.5 mol%.

[0085] The heat-resistant agent is cerium oxide; and the cross-linking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide.

[0086] The preparation method of the above-mentioned high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following steps:

[0087] Add fluorosilicone raw rubber to a vacuum kneader, add modified reinforcing fillers in 4 batches, and knead for 1 hour; after mixing evenly, evacuate and heat treat the materials at 160°C × 2h and a pressure of -0.09MPa to -0.099MPa; cool to 50°C, add a viscosity enhancer to the materials, and mix until uniform; then add a heat-resistant agent, mix until uniform, and obtain a rubber mixture; add a cross-linking agent to the rubber mixture on an open mill, thin it, and sheet it to complete the preparation of the fluorosilicone rubber.

[0088] Example 5

[0089] A high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following components by weight: 100 parts of fluorosilicone raw rubber, 30 parts of modified reinforcing filler, 6 parts of tackifier, 1 part of heat-resistant agent and 0.6 parts of cross-linking agent.

[0090] The fluorosilicone rubber has an ethylene content of 0.01 mol% and a molecular weight of 110×10 4 g / mol.

[0091] The modified reinforcing filler is prepared according to the following method: 100 parts by weight of a BET specific surface area of ​​200 m2 is added to a high-speed mixer. 2 / g fumed silica, raise the temperature to 120°C, add 10 parts by weight of vinyltrimethoxysilane dropwise, the adding time is 50 min, after the adding is completed, high-speed mixing is carried out under nitrogen protection conditions, the rotation speed is 500r / min, the reaction time is 4h, and the obtained reactant is placed in a 100°C oven for heat treatment to constant weight to obtain the product.

[0092] The tackifier is hydroxyl-terminated methyl ethyl vinyl silicone oil, and the kinematic viscosity at 25°C is 102 mm 2 / s, vinyl content 4.5 mol%.

[0093] The heat-resistant agent is cerium oxide; and the cross-linking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide.

[0094] The preparation method of the above-mentioned high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following steps:

[0095] Add fluorosilicone raw rubber to a vacuum kneader, add modified reinforcing fillers in 3 batches, and knead for 2 hours; after mixing evenly, evacuate and heat treat the materials at 160°C × 2h and a pressure of -0.09MPa to -0.099MPa; cool to 50°C, add a viscosity enhancer to the materials, and mix until uniform; then add a heat-resistant agent, mix until uniform, and obtain a rubber mixture; add a cross-linking agent to the rubber mixture on an open mill, thin it, and sheet it to complete the preparation of the fluorosilicone rubber.

[0096] Comparative Example 1

[0097] A metal bonding high temperature vulcanized fluorosilicone rubber as described in Example 2, except that: the tackifier is hydroxyl-terminated methyl silicone oil, and the kinematic viscosity at 25°C is 70 mm 2 / s.

[0098] Comparative Example 2

[0099] A metal bonding high temperature vulcanized fluorosilicone rubber as described in Example 2, except that: the tackifier is trimethyl terminated methyl vinyl silicone oil, and the kinematic viscosity at 25°C is 74 mm 2 / s, vinyl content 5 mol%.

[0100] Comparative Example 3

[0101] A metal bonding high temperature vulcanized fluorosilicone rubber as described in Example 2, except that: the tackifier is hydroxyl terminated vinyl fluorosilicone oil, and the kinematic viscosity at 25°C is 81 mm 2 / s, vinyl content 4.5 mol%.

[0102] Comparative Example 4

[0103] A high-temperature vulcanized fluorosilicone rubber for bonding metals is as described in Example 3, except that the modifier used for treating the filler is trimethylchlorosilane.

[0104] Comparative Example 5

[0105] A high-temperature vulcanized fluorosilicone rubber for bonding metals comprises the following components by weight: 100 parts of fluorosilicone raw rubber, 38 parts of reinforcing filler, 8 parts of hydroxy fluorosilicone oil, 4 parts of tackifier, 2 parts of heat-resistant agent and 0.5 parts of cross-linking agent.

[0106] Wherein, the reinforcing filler is a BET specific surface area of ​​300m2 that has not been treated with a modifier. 2 / g fumed silica; the fluorosilicone rubber, tackifier, heat-resistant agent and cross-linking agent are as described in Example 3.

[0107] In this comparative example, if white carbon black is not treated, the rubber compound will be structured. Therefore, hydroxy fluorosilicone oil is added as a structure control agent during the preparation of fluorosilicone rubber to prevent the rubber compound from being structured.

[0108] The preparation method of the above fluorosilicone rubber comprises the following steps:

[0109] Add 100 parts of fluorosilicone raw rubber and 8 parts of hydroxyfluorosilicone oil into a vacuum kneader, add reinforcing fillers in 4 batches, knead for 1 hour, and after mixing evenly, evacuate and heat treat the materials under the conditions of 150℃×2h and pressure of -0.09MPa to -0.099MPa; after cooling to 50℃, add viscosity enhancer to the materials and mix until uniform; then add heat-resistant agent and mix until uniform to obtain a rubber mixture; add a cross-linking agent to the rubber mixture on an open mill, thin it and sheet it to complete the preparation of fluorosilicone rubber.

[0110] Test example

[0111] The bonding performance of the metal-bonded high-temperature vulcanized fluorosilicone rubber prepared in Examples 1 to 5 and Comparative Examples 1 to 5 was tested, and the specific steps were as follows:

[0112] (1) Treat the metal test piece as follows:

[0113] The stainless steel sheet was wiped with ethanol to remove surface oil, dust, etc.; the stainless steel sheet was placed in an oven for baking at 100°C for 1h to remove residual solvent and moisture on the surface; the stainless steel sheet was taken out of the oven and placed in a dryer to cool to room temperature; a primer was applied to the stainless steel surface (the commercially available Chemlock 608 primer was selected in the embodiment and the comparative example), and the stainless steel sheet was placed in a dryer again, and the next step was performed after the solvent component in the primer was completely volatilized; the primer was applied to the stainless steel sheet twice and dried, and the treatment of the stainless steel sheet was completed.

[0114] (2) 100 g of the sample was laminated to the treated stainless steel sheet, and placed in a mold for a first-stage vulcanization at 170° C. for 15 min and a second-stage vulcanization at 200° C. for 4 h to complete the preparation of the peel-bond test piece;

[0115] (3) Testing the peel strength of the peel test piece and the peel strength after oil immersion, wherein the peel strength is tested according to GB / T 15254. The above embodiments and comparative examples select IRM 903 standard oil to conduct oil resistance test on the high temperature vulcanized fluorosilicone rubber and stainless steel bonding test pieces, the condition is 150°C×72h.

[0116] The performance data of the embodiments and comparative examples are shown in Table 1.

[0117] Table 1 Performance data of Examples 1 to 5 and Comparative Examples 1 to 5

[0118]

[0119] Cohesive failure refers to the visible failure at the fluorosilicone rubber end of the fluorosilicone rubber and stainless steel bonding test piece. From the comparison of the above experimental data, the fluorosilicone rubber prepared by the method of the present invention in Examples 1 to 5 has excellent bonding effect with the metal test piece, and can still maintain at least 80% peeling cohesive failure between the rubber and the metal in a high-temperature oil environment. The hydroxy silicone oil used in Comparative Example 1 does not contain vinyl, resulting in insufficient bonding with the fluorosilicone rubber end. The trimethyl-terminated methyl vinyl silicone oil used in Comparative Example 2 does not contain terminal hydroxyl groups, which affects the adhesion with the metal end. In Comparative Example 3, hydroxyl-terminated vinyl fluorosilicone oil is used as a tackifier. Since it contains a trifluoropropyl group, it has excellent compatibility with the molecular weight of fluorosilicone raw rubber, thereby affecting the amount of tackifier precipitated from the fluorosilicone rubber during the co-vulcanization process. The bonding strength between the fluorosilicone rubber and the metal has partial cohesive failure, but after the high-temperature oil environment test, the peel strength decreases to a poor degree. Comparative Examples 4 and 5 use a white carbon black treatment agent that does not contain vinyl and do not treat white carbon black, which greatly reduces the vinyl group content in the prepared fluorosilicone rubber, resulting in poor bonding between the fluorosilicone rubber and the metal.

[0120] The above embodiments are used to illustrate the present invention, but the present invention is not limited to the above examples, and modifications, additions and substitutions made to the contents involved in the present invention by those skilled in the art also fall within the protection scope of the present invention.

Claims

1. A high temperature vulcanized fluorosilicone rubber for bonding metals, characterized in that: The fluorosilicone rubber comprises the following components by weight: 100 parts of fluorosilicone raw rubber, 2-10 parts of tackifier, 20-60 parts of modified reinforcing filler, 0.5-5 parts of heat-resistant agent, and 0.5-2 parts of cross-linking agent; The fluorosilicone rubber is polymethyltrifluoropropylsiloxane, having the structure shown in the general formula (I): (I) In the general formula (I), R1 and R2 are each independently selected from methyl, vinyl or hydroxyl, x is an integer ≥ 3000, and y is an integer from 1 to 100; The tackifier is a hydroxyl-terminated vinyl organopolysiloxane tackifier, and the tackifier has a structure shown in general formula (II): (II) In the general formula (II), R3 and R4 are each independently selected from a saturated hydrocarbon group or an aromatic group; p is an integer of 1 to 100, and q is an integer of 1 to 200; The modified reinforcing filler is vinyl modified fumed silica.

2. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 1, characterized in that: The molecular weight of the fluorosilicone rubber is 60×10 4 ~160×10 4 g / mol, and the vinyl content is 0.01~2mol%.

3. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 1, characterized in that: The modifier used for the vinyl-modified fumed silica is one or a combination of two or more of vinyl trimethoxysilane, vinyl triethoxysilane, methyl vinyl dimethoxysilane, vinyl tri(β-methoxyethoxy) silane, vinyl tri-tert-butoxysilane, vinyl triacetoxysilane, dimethyl vinyl chlorosilane and methyl vinyl dichlorosilane.

4. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 1, characterized in that: The modified reinforcing filler is prepared according to the following method: adding fumed silica to a mixing device, heating to a reaction temperature, then dripping a modifier into the mixing device, and reacting under nitrogen protection; after the reaction is completed, heat treatment is performed to remove small molecular substances and water generated during the reaction to obtain vinyl-modified fumed silica, which is the modified reinforcing filler.

5. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 4, characterized in that: The BET specific surface area of ​​the fumed silica is 100-400 m 2 / g, and the mass ratio of the fumed silica to the modifier is 100:(10~20).

6. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 4, characterized in that: The reaction temperature is 100-150° C., and the reaction time is 2-6 hours. The heat treatment temperature is 90-100° C., and the heat treatment is performed until constant weight.

7. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 1, characterized in that: In the general formula (II), R3 and R4 are each independently selected from methyl, ethyl, propyl, isopropyl, butyl, hexyl, 2-ethylhexyl, octyl, isooctyl, decyl or phenyl.

8. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 1, characterized in that: The kinematic viscosity of the tackifier at 25°C is 50-500 mm 2 / s.

9. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 1, characterized in that: The vinyl content of the tackifier is 2-10 mol%.

10. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 1, characterized in that: The heat-resistant agent is one or a combination of two or more of iron oxide, cerium oxide, tin oxide, zinc oxide, magnesium oxide and titanium dioxide.

11. The metal bonding high temperature vulcanized fluorosilicone rubber according to claim 1, characterized in that: The crosslinking agent is an organic peroxide crosslinking agent.

12. The method for preparing the metal-bonded high-temperature vulcanized fluorosilicone rubber according to any one of claims 1 to 11, comprising the following steps: (1) Add fluorosilicone raw rubber to the rubber mixing equipment, and add modified reinforcing fillers in 3 to 6 batches for mixing. After mixing evenly, continue kneading for 0.5 h to 2 h, and then perform heat treatment; (2) Lower the temperature of the rubber compound to below 50°C, add a tackifier to the rubber compound and mix until the materials are evenly mixed; (3) Control the temperature of the rubber compound below 50°C, add a heat-resistant agent to the rubber compound and mix until the mixed material is uniform to obtain a mixed rubber; (4) Add a crosslinking agent to the rubber mixture obtained above and mix until uniform to obtain a high-temperature vulcanized fluorosilicone rubber for bonding metals.

13. The method for using the metal bonding high temperature vulcanized fluorosilicone rubber according to any one of claims 1 to 11, comprising the following steps: (1) Treat the metal surface to remove oil, dust, solvents and moisture, then apply a primer on the metal surface and dry it; (2) After the treated metal is bonded to the bonding metal high temperature vulcanized fluorosilicone rubber, high temperature vulcanization is performed to complete the metal bonding.

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