Silicone rubber raw materials, silicone rubber and preparation method, engine cooling water pipe, automobile

Abstract

The present invention discloses a silicone rubber raw material, silicone rubber and a preparation method, an engine cooling water pipe, and an automobile, and relates to the silicone rubber technical field. The silicone rubber raw material includes the following components in parts by mass: 65 to 70 parts of a first methyl vinyl silicone rubber raw rubber; 20 to 30 parts of a second methyl vinyl silicone rubber raw rubber; 8 to 12 parts of a third methyl vinyl silicone rubber raw rubber; 40 to 60 parts of a first white carbon black; 1 to 5 parts of a second white carbon black; 3 to 5 parts of hydroxy silicone oil; 3 to 5 parts of methoxy silicone oil; 1 to 3 parts of carbon black; 1 to 3 parts of cerium oxide; 1 to 3 parts of titanium oxide; 1 to 3 parts of a vulcanizing agent. The silicone rubber raw material provided by the technical solution of the present invention uses conventional white carbon black as a reinforcing agent, and does not require additional additives. The prepared silicone rubber has excellent high temperature resistance and anti-aging properties, has high plasticity, and also has good processing properties of non-stick rollers and a long storage time.

Description

Technical Field

[0001] The invention relates to the technical field of silicone rubber, and in particular to silicone rubber raw materials, silicone rubber and a preparation method, an engine cooling water pipe and an automobile. Background Art

[0002] High temperature vulcanized silicone rubber products have excellent comprehensive properties and have been widely used in aviation, electronics, electrical, chemical, instrumentation, automobile and other industrial fields, as well as medical and health care and daily life. The automobile engine cooling water pipe is an important component connecting the engine and the radiator, which plays the role of sealing, shock resistance and heat exchange. Since the surface temperature of the engine is as high as 200°C or above when it is working, the cooling water pipe in contact with it is required to have excellent high temperature aging resistance. There are two main types of existing radiator hoses: those made of EPDM rubber and those made of silicone. EPDM hoses are relatively affordable, but not as durable as silicone hoses; silicone hoses can withstand higher temperatures and pressures, have good processing properties and excellent high temperature resistance, so they are widely used in automobile engine cooling water pipes.

[0003] At present, the production process of heat dissipation silicone rubber tubes for automobile engines is as follows: first, the vulcanizer and silicone rubber are mixed evenly on the open mill, then the hose with a fixed shape is extruded through an extruder, and finally transferred to a steam tank for vulcanization molding. This process requires that the surface of the silicone rubber must have good dryness before vulcanization molding to ensure that it does not stick to the roller on the open mill, and no scratches are left on the surface of the rubber during the transfer to the steam tank. In order to ensure the non-stick roller performance of silicone rubber, some additives such as stearic acid, paraffin and talcum powder are usually added, but the addition of such additives will reduce the high temperature resistance of silicone rubber and seriously shorten the service life of silicone rubber.

[0004] Therefore, it is still of great significance to develop silicone rubber with excellent high temperature resistance and good non-stick roller processing performance. Summary of the invention

[0005] The main purpose of the invention is to provide a silicone rubber raw material, silicone rubber and a preparation method, an engine cooling water pipe, and an automobile, aiming to solve the problems of poor high temperature resistance and poor non-stick roller processing performance of silicone rubber.

[0006] To achieve the above object, the present invention provides a silicone rubber raw material, comprising the following components in parts by weight:

[0007] 65-70 parts of first methyl vinyl silicone rubber raw rubber;

[0008] 20-30 parts of second methyl vinyl silicone rubber raw rubber;

[0009] 8-12 parts of tertiary methyl vinyl silicone rubber;

[0010] 40-60 parts of first white carbon black;

[0011] 1 to 5 parts of second white carbon black;

[0012] 3-5 parts of hydroxy silicone oil;

[0013] 3-5 parts of methoxy silicone oil;

[0014] 1-3 parts of carbon black;

[0015] 1-3 parts of cerium oxide;

[0016] 1-3 parts of titanium oxide;

[0017] 1 to 3 parts of vulcanizing agent.

[0018] In one embodiment, the first methyl vinyl silicone rubber is a vinyl terminated methyl vinyl silicone rubber; and / or,

[0019] The second methyl vinyl silicone rubber raw rubber is a vinyl terminated methyl vinyl silicone rubber raw rubber; and / or,

[0020] The third methyl vinyl silicone rubber raw rubber is a vinyl terminated methyl vinyl silicone rubber raw rubber; and / or,

[0021] The first silica is fumed silica; and / or,

[0022] The specific surface area of ​​the first white carbon black is 180 to 220 m 2 / g; and / or,

[0023] The second silica is precipitated silica; and / or,

[0024] The specific surface area of ​​the second white carbon black is 180 to 220 m 2 / g; and / or,

[0025] The hydroxy silicone oil is a hydroxyl-terminated dimethyl silicone oil; and / or,

[0026] The hydroxyl content of the hydroxy silicone oil is 0.04-0.08%; and / or,

[0027] The methoxy silicone oil is methoxy-terminated dimethyl silicone oil; and / or,

[0028] The carbon black is furnace black; and / or,

[0029] The specific surface area of ​​the carbon black is 150 to 200 m 2 / g; and / or,

[0030] The particle size of the cerium oxide is 15 to 30 nm; and / or,

[0031] The particle size of the titanium oxide is 15 to 30 nm; and / or,

[0032] The vulcanizing agent includes at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, di-tert-butyl peroxide, dicumyl peroxide and cumyl hydroperoxide.

[0033] In one embodiment, the average molecular weight of the first methyl vinyl silicone rubber is 650,000 to 700,000, the average molecular weight of the second methyl vinyl silicone rubber is 550,000 to 650,000, and the average molecular weight of the third methyl vinyl silicone rubber is 550,000 to 650,000; and / or,

[0034] The molar percentage of vinyl in the first methyl vinyl silicone rubber raw rubber is greater than that in the second methyl vinyl silicone rubber raw rubber, and the molar percentage of vinyl in the second methyl vinyl silicone rubber raw rubber is greater than that in the third methyl vinyl silicone rubber raw rubber.

[0035] In one embodiment, the molar percentage of vinyl in the first methyl vinyl silicone rubber is 0.06-0.08%, the molar percentage of vinyl in the second methyl vinyl silicone rubber is 0.20-0.25%, and the molar percentage of vinyl in the third methyl vinyl silicone rubber is 0.95-1.05%.

[0036] In one embodiment, the silicone rubber raw material includes the following components in parts by weight:

[0037] 65 parts of first methyl vinyl silicone rubber;

[0038] 25 parts of second methyl vinyl silicone rubber;

[0039] 10 parts of tertiary methyl vinyl silicone rubber;

[0040] 50 parts of first white carbon black;

[0041] 1 to 5 parts of second white carbon black;

[0042] 5 parts of hydroxy silicone oil;

[0043] 5 parts of methoxy silicone oil;

[0044] 1 part carbon black;

[0045] 1 part cerium oxide;

[0046] 1 part titanium oxide;

[0047] 1 part vulcanizing agent.

[0048] The present invention provides a method for preparing silicone rubber, which uses the silicone rubber raw material to prepare silicone rubber. The method for preparing silicone rubber comprises the following steps:

[0049] S10, mixing the first methyl vinyl silicone rubber raw rubber, the second methyl vinyl silicone rubber raw rubber, the third methyl vinyl silicone rubber raw rubber, hydroxy silicone oil, methoxy silicone oil and the first white carbon black, and performing a first heat refining to obtain a first mixture;

[0050] S20, mixing the first mixed material with the second white carbon black, and performing a second heat refining to obtain a second mixed material;

[0051] S30, mixing the second mixed material, carbon black, cerium oxide and titanium oxide, and refining the mixture to obtain a silicone rubber compound;

[0052] S40, mixing the silicone rubber compound with a vulcanizing agent, and vulcanizing the mixture to obtain silicone rubber.

[0053] In one embodiment, the temperature of the first heat treatment is 160-170° C.; and / or,

[0054] The first heat treatment time is 1 to 2 hours.

[0055] In one embodiment, the temperature of the second heat treatment is 160-170° C.; and / or,

[0056] The second heat treatment time is 1 to 2 hours.

[0057] In one embodiment, the temperature of the open refining is 20-40° C.; and / or,

[0058] The refining time is 15 to 20 minutes.

[0059] In one embodiment, the vulcanization method includes compression vulcanization on a flat vulcanizer, and the vulcanization temperature is 160-180° C.; and / or,

[0060] The vulcanization time is 5 to 15 minutes.

[0061] The present invention provides a silicone rubber, which is prepared according to the silicone rubber preparation method.

[0062] The present invention provides an engine cooling water pipe, which comprises the silicone rubber.

[0063] The present invention provides a car, comprising the engine cooling water pipe.

[0064] The silicone rubber raw material provided by the technical solution of the present invention uses white carbon black as a reinforcing agent, and utilizes the adsorption and chemical reaction of small molecules by the surface hydroxyl groups of white carbon black to reduce the small molecule residues, thereby improving the non-stick roller performance of the silicone rubber. The silicone rubber prepared by the technical solution of the present invention has excellent high temperature resistance and anti-aging performance, high plasticity, good non-stick roller processing performance and long storage time, and can be used to solve the problems of poor high temperature resistance and poor non-stick roller processing performance of silicone rubber. DETAILED DESCRIPTION

[0065] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0067] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0068] The cooling water pipe of automobile engine is an important part connecting the engine and radiator, which plays the role of sealing, shock resistance and heat exchange. Since the surface temperature of the engine reaches above 200℃ when it is working, the cooling water pipe in contact with it is required to have excellent high temperature aging resistance. There are two main types of existing radiator hoses: those made of EPDM rubber and those made of silicone. EPDM hoses are relatively affordable, but not as durable as silicone hoses; silicone hoses can withstand higher temperatures and pressures, have good processing performance and excellent high temperature resistance, so they are widely used in automobile engine cooling water pipes.

[0069] At present, the production process of heat dissipation silicone rubber tubes for automobile engines is to first mix the vulcanizer and silicone rubber evenly on an open mill, then extrude the hose into a fixed shape through an extruder, and finally transfer it to a steam tank for vulcanization and molding. This process requires that the surface of the silicone rubber has good dryness before vulcanization and molding to ensure that it does not stick to the roller on the open mill, and that no scratches are left on the surface of the rubber during the transfer to the steam tank. In order to ensure the non-stick roller performance of silicone rubber, some additives such as stearic acid, paraffin and talcum powder are usually added. The addition of such additives can improve the non-stick roller performance, but it will reduce the high temperature resistance of silicone rubber and seriously shorten the service life of silicone rubber.

[0070] Therefore, it is of great significance to develop silicone rubber for automobile engine cooling water pipes with excellent high temperature resistance and good non-stick roller processing performance.

[0071] In view of this, the present invention provides a silicone rubber raw material, comprising the following components in parts by weight:

[0072] 65-70 parts of first methyl vinyl silicone rubber raw rubber;

[0073] 20-30 parts of second methyl vinyl silicone rubber raw rubber;

[0074] 8-12 parts of tertiary methyl vinyl silicone rubber;

[0075] 40-60 parts of first white carbon black;

[0076] 1 to 5 parts of second white carbon black;

[0077] 3-5 parts of hydroxy silicone oil;

[0078] 3-5 parts of methoxy silicone oil;

[0079] 1-3 parts of carbon black;

[0080] 1-3 parts of cerium oxide;

[0081] 1 to 3 parts of titanium oxide;

[0082] 1 to 3 parts of vulcanizing agent.

[0083] In order to improve the non-stick roller performance of silicone rubber, conventional silicone rubber raw materials are added with additives such as stearic acid, paraffin and talcum powder on the basis of white carbon black. Although the addition of these additives can improve the non-stick roller performance of silicone rubber, it will reduce the high temperature resistance of silicone rubber and seriously shorten the service life of silicone rubber. In the technical solution of the present invention, the silicone rubber raw material provided uses white carbon black as a reinforcing agent, and silicone rubber with high temperature resistance and good non-stick roller performance can be prepared without the need to add additional additives. The silicone rubber raw material provided by the technical solution of the present invention can not only improve the processing performance of the non-stick roller, but also has excellent high temperature resistance and anti-aging properties, has high plasticity and long storage time, and can be used to solve the problems of poor high temperature resistance and poor non-stick roller processing performance of silicone rubber.

[0084] It should be noted that small molecule residues have high mobility and are easy to migrate from the inside of the silicone rubber to the surface under heating or pressure, forming a thin "oily" layer, causing the silicone rubber surface to become sticky, thereby increasing the adhesion between the rubber and the roller, making the rubber's non-stick roller performance worse; these small molecule residues may also affect the curing process of the silicone rubber, resulting in incomplete surface curing or minor defects, which in turn affects the smoothness and flatness of the silicone rubber surface, making the rubber and the roller more likely to stick, and the non-stick roller performance worse. After adding the second silica, the small molecule residues can be reduced by utilizing the adsorption and chemical reaction of the surface hydroxyl groups of silica to small molecules, thereby improving the non-stick roller performance of the silicone rubber.

[0085] In an embodiment of the present invention, the first methyl vinyl silicone rubber raw rubber is a vinyl terminated methyl vinyl silicone rubber raw rubber.

[0086] In an embodiment of the present invention, the second methyl vinyl silicone rubber raw rubber is a vinyl terminated methyl vinyl silicone rubber raw rubber.

[0087] In an embodiment of the present invention, the third methyl vinyl silicone rubber raw rubber is a vinyl terminated methyl vinyl silicone rubber raw rubber.

[0088] The vinyl terminated methyl vinyl silicone rubber has excellent heat resistance, weather resistance, mechanical properties, electrical insulation properties, and processing properties. In an embodiment of the present invention, the first methyl vinyl silicone rubber, the second methyl vinyl silicone rubber, and the third methyl vinyl silicone rubber are all vinyl terminated methyl vinyl silicone rubber.

[0089] In an embodiment of the present invention, the average molecular weight of the first methyl vinyl silicone rubber raw rubber is 650,000 to 700,000, the average molecular weight of the second methyl vinyl silicone rubber raw rubber is 550,000 to 650,000, and the average molecular weight of the third methyl vinyl silicone rubber raw rubber is 550,000 to 650,000. The selection of methyl vinyl silicone rubber raw rubbers with different molecular weights can improve the processing performance. When the average molecular weight of the methyl vinyl silicone rubber raw rubber is too low, the strength of the rubber is low and it is easy to stick to the roller; when the average molecular weight of the methyl vinyl silicone rubber raw rubber is too high, the fluidity of the rubber is poor, which is not conducive to the processing of the rubber. The selection of the first methyl vinyl silicone rubber raw rubber, the second methyl vinyl silicone rubber raw rubber and the third methyl vinyl silicone rubber raw rubber within the above molecular weight range can achieve better physical properties and processing performance.

[0090] In an embodiment of the present invention, the molar percentage of vinyl in the first methyl vinyl silicone rubber is greater than that in the second methyl vinyl silicone rubber, and the molar percentage of vinyl in the second methyl vinyl silicone rubber is greater than that in the third methyl vinyl silicone rubber. The selection of methyl vinyl silicone rubber with different ethylene contents can improve processing performance. Different vinyl contents in methyl vinyl silicone rubber will also affect the vulcanization activity, heat aging resistance and high temperature compression deformation resistance of silicone rubber, thereby affecting the vulcanization speed of the rubber and the comprehensive performance of the product.

[0091] In an embodiment of the present invention, the molar percentage of vinyl in the first methyl vinyl silicone rubber raw rubber is 0.06-0.08%, the molar percentage of vinyl in the second methyl vinyl silicone rubber raw rubber is 0.20-0.25%, and the molar percentage of vinyl in the third methyl vinyl silicone rubber raw rubber is 0.95-1.05%. Silicone rubber with high vinyl content will form more crosslinking points during the crosslinking process, thereby increasing the crosslinking density. The silicone rubber prepared from the silicone rubber with high crosslinking density has higher mechanical strength, hardness and heat resistance, but the elasticity will decrease; the silicone rubber with low vinyl content has a lower crosslinking density, better elasticity and flexibility, but relatively poor mechanical strength and heat resistance. The ethylene content of the first methyl vinyl silicone rubber raw rubber, the second methyl vinyl silicone rubber raw rubber, and the third methyl vinyl silicone rubber raw rubber is set in the above range, and the strength and heat resistance of the prepared silicone rubber are better. In one embodiment of the present invention, the molecular weight of the first methyl vinyl silicone rubber raw rubber is set to 630,000, and the ethylene content is 0.07%; the molecular weight of the second methyl vinyl silicone rubber raw rubber is set to 630,000, and the ethylene content is 0.23%; the molecular weight of the third methyl vinyl silicone rubber raw rubber is set to 630,000, and the ethylene content is 1.0%.

[0092] In an embodiment of the present invention, the first silica is fumed silica, which can be used as a reinforcing filler to improve the mechanical properties of silicone rubber.

[0093] In an embodiment of the present invention, the specific surface area of ​​the first white carbon black is 180 to 220 m 2 / g. The specific surface area is set at 180-220m 2 / g of the first silica has good processing performance and has a good reinforcement effect, and can improve the tensile strength, tear strength and wear resistance of silicone rubber.

[0094] In an embodiment of the present invention, the second silica is precipitated silica. Adding a small amount of precipitated silica is beneficial to improving the non-stick roller performance of silicone rubber.

[0095] In an embodiment of the present invention, the specific surface area of ​​the second white carbon black is 180 to 220 m 2 / g. The specific surface area is set at 180-220m 2 / g of second silica has good processing performance and can be used to improve the mechanical properties of silicone rubber.

[0096] In an embodiment of the present invention, the hydroxy silicone oil is a hydroxyl-terminated dimethyl silicone oil. The hydroxyl groups in the hydroxy silicone oil can react with the active groups in the silicone rubber to promote the vulcanization process, thereby improving the processing performance, vulcanization performance, mechanical properties, heat resistance and aging resistance of the silicone rubber.

[0097] In the embodiment of the present invention, the hydroxyl content in the hydroxy silicone oil is 0.04-0.08%. Too high a hydroxyl content may result in too high viscosity of the silicone rubber, difficult processing, and unstable performance after vulcanization; too low a hydroxyl content may result in a slow vulcanization speed and no significant improvement in mechanical properties. The silicone rubber prepared by using hydroxyl-terminated dimethyl silicone oil with a hydroxyl content of 0.04-0.08% has better comprehensive performance.

[0098] In an embodiment of the present invention, the methoxy silicone oil is methoxy-terminated dimethyl silicone oil. Methoxy-terminated dimethyl silicone oil has a lower viscosity, which can effectively reduce the viscosity of the silicone rubber mixture, making it easier to process and mix, and can significantly improve the processing performance, mechanical properties, heat resistance and aging resistance of the silicone rubber.

[0099] In an embodiment of the present invention, the carbon black is furnace black. Adding furnace black can significantly improve the mechanical properties of rubber.

[0100] In an embodiment of the present invention, the specific surface area of ​​the carbon black is 150 to 200 m 2 / g. The specific surface area is set at 150-200m 2 / g furnace carbon black has good processing performance.

[0101] In an embodiment of the present invention, the cerium oxide is nano-sized cerium dioxide, and the median particle size (D50) of the cerium oxide is 15 to 30 nm. Cerium dioxide can improve the heat resistance and anti-aging properties of silicone rubber, and the selection of nano-sized cerium dioxide is conducive to uniform filling of cerium oxide into silicone rubber.

[0102] In the embodiment of the present invention, the titanium oxide is nano-sized titanium dioxide, and the median particle size (D50) of the titanium oxide is 15 to 30 nm. Titanium dioxide can improve the heat resistance, anti-aging performance and mechanical properties of silicone rubber. The selection of nano-sized titanium dioxide is conducive to uniform filling of titanium dioxide into silicone rubber.

[0103] In an embodiment of the present invention, the vulcanizing agent includes at least one of 2,5-dimethyl-2.5-bis(tert-butylperoxy)hexane, di-tert-butyl peroxide, diisopropylbenzene peroxide and isopropylbenzene hydroperoxide. The vulcanizing agent is used to promote the silicone rubber to form a stable cross-linked network structure. The peroxide vulcanizing agent is selected as the vulcanizing agent, and the vulcanization effect is better. The prepared silicone rubber has good physical properties, heat resistance and aging resistance.

[0104] In an embodiment of the present invention, the raw material of the silicone rubber includes the following components in parts by weight:

[0105] 65 parts of first methyl vinyl silicone rubber;

[0106] 25 parts of second methyl vinyl silicone rubber;

[0107] 10 parts of tertiary methyl vinyl silicone rubber;

[0108] 50 parts of first white carbon black;

[0109] 1 to 5 parts of second white carbon black;

[0110] 5 parts of hydroxy silicone oil;

[0111] 5 parts of methoxy silicone oil;

[0112] 1 part carbon black;

[0113] 1 part cerium oxide;

[0114] 1 part titanium oxide;

[0115] 1 part vulcanizing agent.

[0116] The present invention provides a method for preparing silicone rubber, which uses the silicone rubber raw material described in the above technical solution to prepare silicone rubber. The method for preparing silicone rubber comprises the following steps:

[0117] S10, mixing the first methyl vinyl silicone rubber raw rubber, the second methyl vinyl silicone rubber raw rubber, the third methyl vinyl silicone rubber raw rubber, hydroxy silicone oil, methoxy silicone oil and the first white carbon black, and performing a first heat refining to obtain a first mixture;

[0118] S20, mixing the first mixed material with the second white carbon black, and performing a second heat refining to obtain a second mixed material;

[0119] S30, mixing the second mixed material, carbon black, cerium oxide and titanium oxide, and refining the mixture to obtain a silicone rubber compound;

[0120] S40, mixing the silicone rubber compound with a vulcanizing agent, and vulcanizing the mixture to obtain silicone rubber.

[0121] The technical solution of the present invention prepares silicone rubber with good high temperature resistance and non-stick roller performance by adding a small amount of second white carbon black, adjusts the addition order and addition process of the second white carbon black, and chooses to add a small amount of the second white carbon black after the first heat refining. The silicone rubber prepared by the preparation method described in the above technical solution has excellent high temperature resistance and anti-aging performance, high plasticity, good non-stick roller processing performance and long storage time, and can be used to solve the problems of poor high temperature resistance and poor non-stick roller processing performance of automobile engine cooling water pipes.

[0122] In the technical solution of the present invention, the first silica is fumed silica, and the second silica is precipitated silica. Conventional preparation of silicone rubber usually uses a single fumed silica or a single precipitated silica, or uses equivalent amounts of fumed silica and precipitated silica together as fillers. In the conventional preparation of silicone rubber, silica and rubber raw rubber are usually added before heat refining, while the technical solution of the present application chooses to add fumed silica before the first heat refining, add precipitated silica after the first heat refining, and perform heat refining again after adding precipitated silica. Compared with the conventional adding method, adding precipitated silica after heat refining is beneficial to improving the non-stick roller performance of silicone rubber and obtaining silicone rubber with good comprehensive performance.

[0123] In an embodiment of the present invention, in step S10, the first white carbon black is added in multiple batches, and the step of adding in multiple batches comprises:

[0124] The first silica is added in multiple batches, wherein the time interval between each batch addition is 15 to 30 minutes. Adding the first silica in batches can improve the dispersibility of the first silica in the material system, which is beneficial to improving the mechanical properties of the prepared silicone rubber. In one embodiment of the present invention, the first silica is added in 4 times, and after each addition of the first silica, the next batch of fumed silica is added after stirring for 30 minutes.

[0125] In an embodiment of the present invention, in step S10, the temperature of the first heat treatment is 160-170°C.

[0126] In an embodiment of the present invention, the first heat treatment lasts for 1 to 2 hours.

[0127] The first heat refining is carried out in a kneader. The process parameters for the first heat refining are set within the above range, so that the raw materials can fully undergo chemical reactions. When the temperature is lower than the above range, the reaction is incomplete, and when the temperature is higher than the above range, the reaction efficiency is low. In one embodiment of the present invention, the temperature of the first heat refining is set to 160° C., and the time of the first heat refining is 1 hour.

[0128] In an embodiment of the present invention, in step S20, the temperature of the second heat treatment is 160-170°C.

[0129] In an embodiment of the present invention, the second heat treatment lasts for 1 to 2 hours.

[0130] The second heat refining is carried out in a kneader. The process parameters for the second heat refining are set within the above range, so that the raw materials can fully undergo chemical reactions. When the temperature is lower than the above range, the reaction is incomplete. When the temperature is higher than the above range, the reaction efficiency is low. In one embodiment of the present invention, the temperature of the second heat refining is set to 160° C., and the time of the second heat refining is 1 hour.

[0131] In an embodiment of the present invention, in step S30, the step of mixing the cooled second mixed material, carbon black, cerium oxide and titanium oxide, refining, filtering and obtaining the silicone rubber compound comprises:

[0132] After the temperature of the second mixed material is reduced to 70-90° C., the second mixed material after the temperature is reduced, carbon black, cerium oxide and titanium oxide are mixed and kneaded to obtain a silicone rubber compound.

[0133] After the second mixture is cooled to 70-90°C, carbon black, cerium oxide and titanium oxide are added to avoid adverse reactions of the rubber material and premature hardening. In one embodiment of the present invention, carbon black, cerium oxide and titanium oxide are added after the second mixture is cooled to 80°C.

[0134] In an embodiment of the present invention, the temperature of the open refining is 20-40°C.

[0135] In an embodiment of the present invention, the time of the open refining is 15 to 20 minutes.

[0136] The step of opening and refining is carried out in a kneader, and the process parameters of the opening and refining are set within the above range to make the raw materials mixed evenly. In one embodiment of the present invention, the opening and refining temperature is set to 40° C. and the opening and refining time is set to 15 minutes.

[0137] In an embodiment of the present invention, in step S40, the vulcanization method includes compression vulcanization on a flat vulcanizer, and the vulcanization temperature is 160-180°C.

[0138] In an embodiment of the present invention, the vulcanization time is 5 to 15 minutes.

[0139] When the process parameters during vulcanization are set within this range, the vulcanization reaction can be fully carried out, the generation of bubbles and cracks is reduced, and the surface quality of the silicone rubber product is high. In one embodiment of the present invention, the vulcanization temperature is set to 170° C. and the vulcanization time is set to 10 minutes.

[0140] The present invention provides a silicone rubber, which is prepared according to the silicone rubber preparation method.

[0141] The present invention provides an engine cooling water pipe, which includes the silicone rubber. The engine cooling water pipe includes all technical solutions of the silicone rubber, and thus has all the beneficial effects of the silicone rubber, which will not be described in detail in the present invention.

[0142] The present invention provides a car, the car includes the engine cooling water pipe, and the car includes all technical solutions of the engine cooling water pipe, thus having all the beneficial effects of the engine cooling water pipe, which will not be described in detail in the present invention.

[0143] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0144] Example 1

[0145] A silicone rubber raw material, comprising the following components in parts by weight:

[0146] 70 parts of the first methyl vinyl silicone rubber raw rubber, 22 parts of the second methyl vinyl silicone rubber raw rubber, 8 parts of the third methyl vinyl silicone rubber raw rubber, 40 parts of fumed silica, 1 part of precipitated silica, 3 parts of hydroxy silicone oil, 3 parts of methoxy silicone oil, 3 parts of furnace carbon black, 3 parts of cerium oxide, and 3 parts of titanium oxide;

[0147] Wherein, the molecular weight of the first methyl vinyl silicone rubber raw rubber is 630,000 and the ethylene content is 0.07%;

[0148] The molecular weight of the second methyl vinyl silicone rubber raw rubber is 630,000 and the ethylene content is 0.23%;

[0149] The molecular weight of the third methyl vinyl silicone rubber raw rubber is 630,000 and the ethylene content is 1.0%;

[0150] The fumed silica is HL200 with a specific surface area of ​​205 m 2 / g;

[0151] The specific surface area of ​​the precipitated white carbon black is 200 m 2 / g;

[0152] The hydroxy silicone oil is hydroxy-terminated polydimethyl polysiloxane, with a hydroxyl content of 8%;

[0153] The methoxy silicone oil is methoxy-terminated polydimethyl polysiloxane;

[0154] The specific surface area of ​​the furnace carbon black is 200m 2 / g.

[0155] Example 2

[0156] A silicone rubber raw material, comprising the following components in parts by weight:

[0157] 68 parts of the first methyl vinyl silicone rubber raw rubber, 20 parts of the second methyl vinyl silicone rubber raw rubber, 12 parts of the third methyl vinyl silicone rubber raw rubber, 60 parts of fumed silica, 1 part of precipitated silica, 4 parts of hydroxy silicone oil, 4 parts of methoxy silicone oil, 2 parts of furnace carbon black, 2 parts of cerium oxide, and 2 parts of titanium oxide.

[0158] Example 3

[0159] A silicone rubber raw material, comprising the following components in parts by weight:

[0160] 65 parts of the first methyl vinyl silicone rubber raw rubber, 25 parts of the second methyl vinyl silicone rubber raw rubber, 10 parts of the third methyl vinyl silicone rubber raw rubber, 50 parts of fumed silica, 1 part of precipitated silica, 5 parts of hydroxy silicone oil, 5 parts of methoxy silicone oil, 1 part of furnace carbon black, 1 part of cerium oxide, and 1 part of titanium oxide.

[0161] Example 4

[0162] Compared with Example 3, the difference is that the mass fraction of precipitated silica is 3 parts.

[0163] Example 5

[0164] Compared with Example 3, the difference is that the mass fraction of precipitated silica is 5 parts.

[0165] Example 6

[0166] A method for preparing silicone rubber comprises the following steps:

[0167] (1) 65 parts of a first methyl vinyl silicone rubber raw rubber, 25 parts of a second methyl vinyl silicone rubber raw rubber, 10 parts of a third methyl vinyl silicone rubber raw rubber, 5 parts of hydroxy silicone oil, and 5 parts of methoxy silicone oil are mixed and kneaded in a kneader for 3 to 5 minutes; then 50 parts of fumed silica are added to the kneader in 4 batches, and stirred for 30 minutes after each addition; after the fumed silica is added for the last time and stirred to form, the temperature is raised to 160° C., vacuumized, and the first heat refining is performed, and the first mixture is obtained after the heat refining for 1 hour;

[0168] (2) mixing the first mixed material obtained in step (1) with 1 part of precipitated silica, evacuating the mixture, and performing a second heat refining at 160° C. for 1 hour to obtain a second mixed material;

[0169] (3) After the second mixed material obtained in step (2) is cooled to 80° C., 1 part of furnace carbon black, 1 part of cerium oxide and 1 part of titanium oxide are added, kneading for 30 minutes, refining at 40° C. for 15 minutes, filtering, and obtaining a silicone rubber compound;

[0170] (4) The silicone rubber obtained in step (3) is mixed with 1 part of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and subjected to compression vulcanization on a flat vulcanizer at a vulcanization temperature of 170° C. for 10 min to obtain silicone rubber.

[0171] Comparative Example 1

[0172] Compared with Example 1, the difference is that no precipitated silica is contained.

[0173] Comparative Example 2

[0174] Compared with Example 6, the difference is that the precipitated silica is added before the hot refining, and the specific steps are as follows:

[0175] (1) 65 parts of a first methyl vinyl silicone rubber raw rubber, 25 parts of a second methyl vinyl silicone rubber raw rubber, 10 parts of a third methyl vinyl silicone rubber raw rubber, 5 parts of hydroxy silicone oil, and 5 parts of methoxy silicone oil are mixed and kneaded in a kneader for 3 to 5 minutes; then 50 parts of fumed silica are added to the kneader in 4 batches, and stirred for 30 minutes after each addition; when the fumed silica is added for the last time, the fumed silica and 1 part of precipitated silica are added to the kneader together and stirred to form, and then the temperature is raised to 160° C., vacuumized, and the first heat refining is performed, and the first mixture is obtained after the heat refining for 2 hours;

[0176] (2) Same as step (2) of Example 6;

[0177] (3) Same as step (3) of Example 6.

[0178] Comparative Example 3

[0179] Compared with Example 6, the difference is that precipitated silica, furnace carbon black, cerium oxide and titanium oxide are added together after cooling. The specific steps are as follows:

[0180] (1) 65 parts of a first methyl vinyl silicone rubber raw rubber, 25 parts of a second methyl vinyl silicone rubber raw rubber, 10 parts of a third methyl vinyl silicone rubber raw rubber, 5 parts of hydroxy silicone oil, and 5 parts of methoxy silicone oil are mixed and kneaded in a kneader for 3 to 5 minutes; then 50 parts of fumed silica are added to the kneader in 4 batches, and stirred for 30 minutes after each addition; after the fumed silica is added for the last time and stirred to form, the temperature is raised to 160° C., vacuumized, and the first heat refining is performed, and the first mixture is obtained after the heat refining for 2 hours;

[0181] (2) After the first mixed material obtained in step (1) is cooled to 80° C., 1 part of precipitated silica, 1 part of furnace carbon black, 1 part of cerium oxide and 1 part of titanium oxide are added, kneaded for 30 minutes, mixed and filtered to obtain a silicone rubber compound;

[0182] (3) Same as step (3) of Example 6.

[0183] Comparative Example 4

[0184] Compared with Example 6, the difference is that stearic acid is used instead of precipitated silica, and the specific steps are as follows:

[0185] (1) 65 parts of a first methyl vinyl silicone rubber raw rubber, 25 parts of a second methyl vinyl silicone rubber raw rubber, 10 parts of a third methyl vinyl silicone rubber raw rubber, 5 parts of hydroxy silicone oil, 5 parts of methoxy silicone oil and 0.2 parts of stearic acid are mixed and kneaded in a kneader for 3 to 5 minutes; then 50 parts of fumed silica are added to the kneader in 4 batches, and stirred for 30 minutes after each addition; after the fumed silica is added for the last time and stirred to form, the temperature is raised to 160° C., vacuumized, and the first heat refining is performed, and the first mixture is obtained after the heat refining for 2 hours;

[0186] (2) Same as step (2) of Example 6;

[0187] (3) Same as step (3) of Example 6.

[0188] Performance Testing

[0189] The silicone rubber raw materials of Examples 1-5 and Comparative Example 1 were provided and prepared into silicone rubber according to the method of Example 6. The aging resistance of the silicone rubber prepared in Examples 1-5 and Comparative Example 1-4 was tested, and the aging resistance was evaluated by testing hardness, tensile strength, elongation and tear strength. The plasticity, accelerated structuring, storage time and ease of rolling off of the silicone rubber prepared in Examples 1-5 and Comparative Example 1-4 were tested.

[0190] Hardness test: Test the hardness of the material according to the test requirements of GB / T 528-2009. Place the sample on the test stand of the digital hardness tester, pull down the joystick, measure the hardness of different parts of each rubber block three times, and calculate the average value. There are two rubber blocks for each rubber material, and the average value is taken after the test. The test results are shown in Table 1.

[0191] Tensile strength test: According to GB / T 528-2008, a dumbbell or ring-shaped standard specimen is stretched on a tensile testing machine with a moving clamp or pulley moving at a constant speed. The force and elongation values ​​of the specimen during the continuous stretching process and when it breaks are recorded as required. The test results are shown in Table 1.

[0192] Elongation: According to GB / T 528-2008, a dumbbell or ring-shaped standard specimen is stretched on a tensile testing machine with a moving clamp or pulley moving at a constant speed. The force and elongation values ​​of the specimen during the continuous stretching process and when it breaks are recorded as required. The test results are shown in Table 1.

[0193] Tear strength: According to GB / T 529-2008, use a tensile testing machine to continuously stretch a sample with or without a cut at a specified speed until the sample is torn. The measured force value is calculated using the specified calculation method to calculate the tear strength.

[0194] Plasticity test: According to GB / T 12828-2006, a certain volume of sample is preheated at the specified test temperature for 15.0min±0.5min, and then a pressure of 49.0N is applied within the specified time to measure the height (plasticity value) of the sample. The tested sample is restored at the test temperature for a specified time. The height of the sample after recovery is measured, and the difference between the two heights is the recovery value. The test results are shown in Table 2.

[0195] Accelerated structural test: Take 100g of sample and bake it in a 105℃ oven for 72 hours. Take it out and cool it for 30 minutes. Then, mix it on a mixing mill until the raw edges of the rubber are smooth. The number of times the mixing mill is opened is recorded. The test results are shown in Table 2.

[0196] Storage time test: Take a 20KG sample and place it at room temperature. Take 100g of the rubber every 10 days to evaluate whether it is structured. The time when the structure begins to appear is the maximum storage time. The test results are shown in Table 2.

[0197] Roll-off ease test: Use a rolling ball method initial viscosity tester to test the viscosity of the rubber compound. The greater the viscosity, the worse the roll-off performance and the worse the non-stick roller performance. The test steps are as follows:

[0198] Adjust the inclined ball rolling device to a horizontal position, and adjust the inclination angle of the inclined plate to 30° (unless otherwise specified); roll out the rubber compound into a 3mm plane, place it on the inclined plate, and cover the specified position with a polyester film as an auxiliary rolling section. The 100mm range below the auxiliary rolling section is the test section. Use rubber compound to fix both sides of the auxiliary rolling section and the lower end of the sample on the inclined plate, so that the sample fits evenly on the plate;

[0199] Use tweezers to clamp the steel ball into the ball releaser so that the center of the steel ball is on the rolling starting line. After adjusting the ball release position, gently open the ball releaser and record the time it takes for the steel ball to roll from the top to the bottom.

[0200] The criteria for judging the ease of rolling off are shown in Table 2. The longer the rolling time of the steel ball is, the greater the viscosity of the rubber compound is. The test results of the ease of rolling off are shown in Table 3.

[0201] Table 1 Aging ability test results of Examples 1-5 and Comparative Examples 1-4

[0202]

[0203] Table 2 Criteria for judging the ease of roll removal

[0204]

[0205]

[0206] Table 3 Test results of plasticity, accelerated structuring, storage time and ease of roll removal of Examples 1-5 and Comparative Examples 1-4

[0207] Plasticity Accelerate structuring Storage time Ease of Rolling Off Example 1 260 5 210 days Level 5 Example 2 360 12 90 days Level 6 Example 3 300 7 210 days Level 6 Example 4 320 8 180 days Level 7 Example 5 330 12 90 days Level 8 Comparative Example 1 285 7 210 days Level 4 Comparative Example 2 290 7 210 days Level 4 Comparative Example 3 360 20 40 days Level 8 Comparative Example 4 286 7 210 days Level 6

[0208] It can be seen from the test results of Table 1, Table 2 and Table 3 that the plasticity and ease of rolling off of Examples 1-5 are better than those of Comparative Example 1, indicating that adding an appropriate amount of precipitated silica is beneficial to improving the plasticity and non-stick roller performance of silicone rubber; it can be seen from the test results of Examples 3-5 that with the increase in the addition amount of precipitated silica, the plasticity and non-stick roller performance of silicone rubber tend to improve, and the accelerated structuring and storage time test results tend to deteriorate, among which Example 4 has better comprehensive performance.

[0209] From the test results of Example 4 and Comparative Examples 2-3, it can be seen that Comparative Example 2 is more difficult to remove from the roller than Example 4, indicating that the non-stick roller performance of Example 4 is better than that of Comparative Example 2; the accelerated structuring result and storage time test result of Example 4 are better than those of Comparative Example 3. The above results show that the addition order and addition temperature of precipitated silica will affect the comprehensive properties of the prepared silicone rubber.

[0210] From the test results of Examples 1-5 and Comparative Example 4, it can be seen that after aging (250°C*72H), the tensile strength and elongation test results of the silicone rubber in Comparative Example 4 deteriorated, and the plasticity results deteriorated. The test results of the ease of roller removal of Examples 1-5 are equivalent to those of Comparative Example 4. The above results show that adding an appropriate amount of precipitated silica and stearic acid can improve the non-stick roller performance, but the aging resistance and plasticity when adding precipitated silica are better than those when adding stearic acid.

[0211] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the technical concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A silicone rubber raw material, characterized in that: The composition comprises the following components in parts by weight: 65-70 parts of first methyl vinyl silicone rubber raw rubber; 20-30 parts of second methyl vinyl silicone rubber raw rubber; 8-12 parts of tertiary methyl vinyl silicone rubber; 40-60 parts of first white carbon black; 1 to 5 parts of second white carbon black; 3-5 parts of hydroxy silicone oil; 3-5 parts of methoxy silicone oil; 1-3 parts of carbon black; 1-3 parts of cerium oxide; 1-3 parts of titanium oxide; 1 to 3 parts of vulcanizing agent.

2. The silicone rubber raw material according to claim 1, characterized in that: The first methyl vinyl silicone rubber raw rubber is a vinyl terminated methyl vinyl silicone rubber raw rubber; and / or, The second methyl vinyl silicone rubber raw rubber is a vinyl terminated methyl vinyl silicone rubber raw rubber; and / or, The third methyl vinyl silicone rubber raw rubber is a vinyl terminated methyl vinyl silicone rubber raw rubber; and / or, The first silica is fumed silica; and / or, The specific surface area of ​​the first white carbon black is 180 to 220 m 2 / g; and / or, The second silica is precipitated silica; and / or, The specific surface area of ​​the second white carbon black is 180 to 220 m 2 / g; and / or, The hydroxy silicone oil is a hydroxyl-terminated dimethyl silicone oil; and / or, The hydroxyl content of the hydroxy silicone oil is 0.04-0.08%; and / or, The methoxy silicone oil is methoxy-terminated dimethyl silicone oil; and / or, The carbon black is furnace black; and / or, The specific surface area of ​​the carbon black is 150 to 200 m 2 / g; and / or, The particle size of the cerium oxide is 15 to 30 nm; and / or, The particle size of the titanium oxide is 15 to 30 nm; and / or, The vulcanizing agent includes at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, di-tert-butyl peroxide, dicumyl peroxide and cumyl hydroperoxide.

3. The silicone rubber raw material according to claim 1, characterized in that: The average molecular weight of the first methyl vinyl silicone rubber raw rubber is 650,000 to 700,000, the average molecular weight of the second methyl vinyl silicone rubber raw rubber is 550,000 to 650,000, and the average molecular weight of the third methyl vinyl silicone rubber raw rubber is 550,000 to 650,000; and / or, The molar percentage of vinyl in the first methyl vinyl silicone rubber raw rubber is greater than that in the second methyl vinyl silicone rubber raw rubber, and the molar percentage of vinyl in the second methyl vinyl silicone rubber raw rubber is greater than that in the third methyl vinyl silicone rubber raw rubber.

4. The silicone rubber raw material according to claim 3, characterized in that: The molar percentage of vinyl in the first methyl vinyl silicone rubber is 0.06-0.08%, the molar percentage of vinyl in the second methyl vinyl silicone rubber is 0.20-0.25%, and the molar percentage of vinyl in the third methyl vinyl silicone rubber is 0.95-1.05%.

5. The silicone rubber raw material according to any one of claims 1 to 4, characterized in that: The composition comprises the following components in parts by weight: 65 parts of first methyl vinyl silicone rubber; 25 parts of second methyl vinyl silicone rubber; 10 parts of tertiary methyl vinyl silicone rubber; 50 parts of first white carbon black; 1 to 5 parts of second white carbon black; 5 parts of hydroxy silicone oil; 5 parts of methoxy silicone oil; 1 part carbon black; 1 part cerium oxide; 1 part titanium oxide; 1 part vulcanizing agent.

6. A method for preparing silicone rubber, characterized in that: Silicone rubber is prepared by using the silicone rubber raw material according to any one of claims 1 to 5, and the preparation method of the silicone rubber comprises the following steps: S10, mixing the first methyl vinyl silicone rubber raw rubber, the second methyl vinyl silicone rubber raw rubber, the third methyl vinyl silicone rubber raw rubber, hydroxy silicone oil, methoxy silicone oil and the first white carbon black, and performing a first heat refining to obtain a first mixture; S20, mixing the first mixed material with the second white carbon black, and performing a second heat refining to obtain a second mixed material; S30, mixing the second mixed material, carbon black, cerium oxide and titanium oxide, and refining the mixture to obtain a silicone rubber compound; S40, mixing the silicone rubber compound with a vulcanizing agent, and vulcanizing the mixture to obtain silicone rubber.

7. The method for preparing silicone rubber according to claim 6, characterized in that: The temperature of the first heat treatment is 160-170°C; and / or, The first heat treatment time is 1 to 2 hours; and / or, The temperature of the second heat treatment is 160-170°C; and / or, The second heat treatment time is 1 to 2 hours; and / or, The refining temperature is 20-40°C; and / or The refining time is 15 to 20 minutes; and / or, The vulcanization method includes compression vulcanization on a flat vulcanizer, and the vulcanization temperature is 160-180° C.; and / or, The vulcanization time is 5 to 15 minutes.

8. A silicone rubber, characterized in that: The silicone rubber is prepared according to the method for preparing silicone rubber according to claim 6 or 7.

9. An engine cooling water pipe, characterized in that: The engine cooling water pipe comprises the silicone rubber as claimed in claim 8.

10. An automobile, characterized in that: The automobile comprises the engine cooling water pipe according to claim 9.

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