High-performance oil-resistant addition type liquid silicone rubber and preparation method thereof

Abstract

The invention discloses high-performance oil-resistant addition type liquid silicone rubber and a preparation method thereof. The addition type liquid silicone rubber comprises a component A and a component B which are equal in mass, the component A comprises base rubber, vinyl silicone oil, a compound oil-resistant additive and a catalyst; the component B comprises base rubber, vinyl silicone oil, hydrogen-containing silicone oil and an inhibitor; the base rubber comprises vinyl silicone oil and high-performance high-dispersion precipitated silica # imgabs0 # C368 with the specific surface area of 100-200m < 2 > / g; the compound oil-resistant additive is diatomite, cerium oxide and calcium silicate. The oil-resistant additive is compounded to obviously improve the oil resistance of the addition type liquid silicone rubber in an oil immersion environment, and meanwhile, the specific high-performance high-dispersion precipitation method silicon dioxide is adopted as a reinforcing filler, so that the prepared addition type liquid silicone rubber has excellent mechanical properties and flowability. Compared with the traditional solid oil-resistant silicone rubber, the solid oil-resistant silicone rubber has the advantages of higher production efficiency and wider application scene.

Description

Technical Field

[0001] The invention relates to the technical field of modified liquid silicone rubber, and more specifically to a high-performance oil-resistant addition-type liquid silicone rubber and a preparation method thereof. Background Art

[0002] Silicone rubber has excellent properties such as high and low temperature resistance, weather resistance, and physiological inertness, and is widely used in automotive accessories, daily life, medical care, aerospace, and other fields. However, silicone rubber generally has poor oil resistance. It will swell after being immersed in fuel and various mineral oils for a long time, and its mechanical properties will drop significantly, which cannot meet the high temperature and oil resistance requirements of silicone rubber seals in automobiles and industrial equipment. Although the existing fluorosilicone rubber has good oil resistance, its cost is relatively high and cannot be widely used. In addition, traditional oil-resistant silicone rubber is generally solid silicone rubber, which has low production efficiency, no fluidity, and relatively few application scenarios compared to liquid silicone rubber. Therefore, it is of great significance to develop oil-resistant liquid silicone rubber.

[0003] Addition-type liquid silicone rubber is composed of linear polysiloxane containing vinyl as the base polymer, low-polymerization hydrogenated silicone oil as the crosslinking agent, and transition metal complex as the catalyst, and an elastomer with a network structure is formed through an addition reaction. At present, the method of improving the oil resistance of addition-type liquid silicone rubber in the prior art is usually to introduce a methyltrifluoropropylsiloxane structure into the liquid silicone rubber, and use alkaline earth metal oxide or hydroxide acceptor fillers, for example. However, as mentioned above, the introduction of fluorine-containing groups is costly and cannot be widely used. The use of alkaline earth metal oxide or hydroxide acceptor fillers is low in cost and has the prospect of widespread use. However, while alkaline earth metal oxide or hydroxide acceptor fillers improve oil resistance, they will have an adverse effect on other properties of silicone rubber, such as mechanical properties, fluidity, etc. At the same time, the use of alkaline earth metal oxide or hydroxide acceptor fillers alone has limited improvement in oil resistance. Summary of the invention

[0004] The purpose of the present invention is to overcome the above defects and deficiencies in the prior art and provide a high-performance oil-resistant addition-type liquid silicone rubber. The oil resistance of the addition-type liquid silicone rubber in an oil-immersion environment is significantly improved by adding a compound oil-resistant additive. As reinforcing fillers, the prepared addition-type liquid silicone rubber has both excellent mechanical properties and fluidity.

[0005] The second object of the present invention is to provide a method for preparing the high-performance oil-resistant addition-type liquid silicone rubber.

[0006] The third object of the present invention is to provide an application of the high-performance oil-resistant addition-type liquid silicone rubber.

[0007] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0008] A high-performance oil-resistant addition-type liquid silicone rubber composition, comprising a component A and a component B of equal mass;

[0009] The component A comprises the following raw materials in parts by weight: 70-80 parts of base rubber, 18-22 parts of vinyl silicone oil, 10-30 parts of compound oil-resistant additive, and 0.01-0.1 parts of catalyst;

[0010] The component B comprises the following raw materials in parts by weight: 80-90 parts of base rubber, 8-12 parts of vinyl silicone oil, and 4-6 parts of hydrogenated silicone oil;

[0011] The base rubber in component A and component B comprises the following raw materials in parts by weight: 90 to 110 parts of vinyl silicon, 35 to 45 parts of a specific surface area of ​​100 to 200 m 2 / g high performance and highly dispersed precipitated silica 35-45 parts of vinyl silicone oil;

[0012] The compound oil-resistant auxiliary agent is diatomaceous earth, cerium oxide and calcium silicate, and the mass ratio is 1-3:1-3:5-7.

[0013] The present invention significantly improves the oil resistance of addition-type liquid silicone rubber in an oil-immersed environment by adding a specific compound oil-resistant additive, and also adopts the high-performance and highly dispersed precipitated silica developed by the applicant in the early stage. As reinforcing fillers, the addition-type liquid silicone rubber has excellent mechanical properties and fluidity. Compared with traditional solid oil-resistant silicone rubber, it has higher production efficiency and wider application scenarios.

[0014] Furthermore, the component A also includes 0.1 to 1 part of a structure control agent. The structure control agent can be added to improve processing performance, enhance product performance stability, adjust vulcanization characteristics, etc.

[0015] Furthermore, the structure control agent includes but is not limited to hydroxy silicone oil.

[0016] Preferably, the hydroxyl mass content of the hydroxyl silicone oil is 3% to 9%.

[0017] Preferably, the viscosity of the hydroxy silicone oil is 20 to 500 mPa·s.

[0018] Preferably, the structure is controlled to be a hydroxyl-terminated polysiloxane with a viscosity of 50 mPa·s and a hydroxyl mass content of 8%.

[0019] Furthermore, the component B also includes 0.01 to 0.1 parts of a silica inhibitor. Since the base rubber, the crosslinking agent and the catalyst can undergo a hydrosilylation reaction once they come into contact, and the reaction can also proceed slowly at room temperature, in order to obtain a longer service life or "shelf life", the activity of the catalyst at room temperature can be delayed or inhibited by adding an appropriate silica inhibitor.

[0020] Furthermore, the silica gel inhibitor is an acetylenic alcohol compound or an organic peroxide.

[0021] Preferably, the silica gel inhibitor includes but is not limited to any one or more of 1-ethynyl-1-cyclohexanol, tetramethyltetravinylcyclotetrasiloxane, 2-methyl-3-butynyl-2-ol, 3-methyl-1-ethynyl-3-ol, 3,5-dimethyl-1-hexynyl-3-ol, and 3-methyl-1-dodecyn-3-ol.

[0022] Preferably, the silica gel inhibitor is 1-ethynyl-1-cyclohexanol.

[0023] Furthermore, the base rubber also includes 5 to 20 parts of hexamethyldisilazane, 1 to 5 parts of dimethylvinylethoxysilane, and 1 to 5 parts of pure water. By adding hexamethyldisilazane and dimethylvinylethoxysilane and controlling their dosage, the mechanical strength of the silicone rubber can be further adjusted by controlling the surface hydroxyl groups of the precipitated silica treated as a reinforcing agent.

[0024] Furthermore, the viscosity of the vinyl silicone oil is 500 to 100,000 mPa·s, and the mass content of vinyl is 0.06 to 3.0%.

[0025] Preferably, the viscosity of the vinyl silicone oil in component A and component B is 10000 mPa·s, and the mass content of vinyl is 0.1%; the viscosity of the vinyl silicone oil in the base rubber is 20000 mPa·s, and the mass content of vinyl is 0.08%.

[0026] More preferably, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane.

[0027] Furthermore, the hydrogen-containing silicone oil comprises polydimethylhydrogensiloxane containing Si-H in the side chain; wherein the hydrogen content of the polydimethylhydrogensiloxane is 0.1-2.0%.

[0028] Furthermore, the high-performance, highly dispersed precipitated silica has a surface area of ​​140 to 160 m 2 / g.

[0029] Preferably, the high-performance, highly dispersed precipitated silica has a surface area of ​​150 m 2 / g.

[0030] Furthermore, the catalyst is a platinum catalyst.

[0031] Furthermore, the concentration of the platinum catalyst is 1000-5000 ppm.

[0032] Preferably, the platinum catalyst is a 3000 ppm Custer platinum catalyst.

[0033] As a preferred implementation method, the high-performance oil-resistant addition-type liquid silicone rubber composition comprises component A and component B of equal mass;

[0034] The component A comprises the following raw materials in parts by weight: 75 parts of base rubber, 20 parts of vinyl silicone oil, 20 parts of compound oil-resistant additive, 0.5 parts of structure control agent, and 0.05 parts of catalyst;

[0035] The component B comprises the following raw materials in parts by weight: 85 parts of base rubber, 10 parts of vinyl silicone oil, 5 parts of hydrogenated silicone oil, and 0.01 parts of silicone inhibitor;

[0036] The base glue in component A and component B contains the following raw materials in parts by weight: 60 parts of vinyl silicon, 10 parts of hexamethyldisilazane, 3 parts of dimethylvinylethoxysilane, 3 parts of pure water, 40 parts of a specific surface area of ​​150m 2 / g high performance and highly dispersed precipitated silica 40 parts of vinyl silicone oil;

[0037] The compound oil-resistant additive is diatomaceous earth, cerium oxide and calcium silicate, and the mass ratio is 2:2:6.

[0038] The present invention also provides a method for preparing any of the above-mentioned addition-type liquid silicone rubbers, which comprises mixing component A and component B of any of the above-mentioned addition-type liquid silicone rubber compositions, and mixing them in vacuum to obtain the addition-type liquid silicone rubber compound.

[0039] Furthermore, the preparation method of the component A is to add vinyl silicone oil, a compound oil-resistant additive, a structure control agent and a catalyst into the base rubber, and mix them in vacuum to obtain the component A.

[0040] Furthermore, the preparation method of the component B is to add vinyl silicone oil, hydrogen-containing silicone oil and silicone inhibitor into the base rubber, and mix them in vacuum to obtain the component B.

[0041] Furthermore, the preparation method of the base glue is to first mix 50% to 70% vinyl silicone oil, high-performance high-dispersion precipitated silica, hexamethyldisilazane, dimethylvinylethoxysilane, and pure water, heat and knead them in a vacuum, then add the remaining 30% to 50% vinyl silicone oil to dilute, heat and knead them in a vacuum, and obtain the base glue.

[0042] The present invention also provides the use of any of the above-mentioned addition-type liquid silicone rubber compositions in the preparation of high-performance oil-resistant addition-type silicone rubber. The high performance refers to strong mechanical properties and good fluidity.

[0043] The present invention also provides use of any of the above-mentioned addition-type liquid silicone rubber compositions in preparing sealing elements.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention provides a high-performance oil-resistant addition-type liquid silicone rubber. The present invention significantly improves the oil resistance of the addition-type liquid silicone rubber in an oil-immersed environment by adding a compounded oil-resistant additive. At the same time, high-performance and highly dispersed precipitated silica is used. As reinforcing fillers, the addition-type liquid silicone rubber has excellent mechanical properties and fluidity. Compared with traditional solid oil-resistant silicone rubber, it has higher production efficiency and wider application scenarios. DETAILED DESCRIPTION

[0046] The present invention is further described below in conjunction with specific examples of the specification, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0047] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0048] Vinyl silicone oil: vinyl-terminated polydimethylsiloxane, viscosity 10000mPa·s, vinyl mass content 0.1%, Shenzhen Jipeng Silicone Fluoride Materials; viscosity 20000mPa·s, vinyl mass content 0.08%, Shenzhen Jipeng Silicone Fluoride Materials.

[0049] Hydrogen-containing silicone oil: polydimethylhydrogensiloxane, hydrogen content 1.6%, Xingchi Chemical;

[0050] Structure control agent: Hydroxy silicone oil: hydroxyl-terminated polysiloxane, viscosity 50 mPa·s, hydroxyl mass content 8%, Xingchi Chemical.

[0051] Platinum catalyst: Custer platinum catalyst, content is 3000ppm, Guangzhou Siyou New Materials.

[0052] Silica gel inhibitor: 1-ethynyl-1-cyclohexanol, general type, Guangzhou Siyou New Materials.

[0053] Diatomaceous earth: ultra white 600 mesh diatomaceous earth powder, Jiangsu Bosite Chemical.

[0054] Cerium oxide: D50 is 50nm, Liaoning Lanen Environmental Protection Technology.

[0055] Calcium silicate: ultrafine 300 mesh calcium silicate powder, Zhengzhou Wanchuang Chemical.

[0056] High performance and highly dispersed precipitated silica: Jinsanjiang Silicon Materials.

[0057] Commercially available conventional precipitated silica: Commercially available conventional type.

[0058] Hexamethyldisilazane: KH-620, Hangzhou Jessica Chemical.

[0059] Dimethylvinylethoxysilane: VM-17, Zhejiang Jiahui New Materials.

[0060] Example 1

[0061] (1) 60 parts of vinyl silicone oil with a viscosity of 20,000 mPa·s and a vinyl content of 0.08% were added to a vacuum kneader, and 10 parts of hexamethyldisilazane, 3 parts of dimethylvinylethoxysilane and 3 parts of pure water were added and mixed evenly. A total of 40 parts of a specific surface area of ​​150 m 2 / g of high-performance, highly dispersed precipitated silica, kneading at room temperature for 100 minutes, turning on the heating mode, turning on the vacuum equipment after reaching the target temperature of 180 degrees Celsius, kneading for 100 minutes under vacuum heating, adding 40 parts of vinyl silicone oil with a viscosity of 20000mPa·s and a vinyl mass content of 0.08% to dilute the rubber, and continuing to knead for 100 minutes under vacuum to obtain a base rubber for standby use;

[0062] (2) 75 parts of base rubber, 20 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl content of 0.1%, 20 parts of a composite oil-resistant additive (the mass ratio of the components is diatomaceous earth: cerium oxide: calcium silicate = 2:2:6), 0.5 parts of a structure control agent, and 0.05 parts of a 3000 ppm platinum catalyst are mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there are no obvious bubbles in the rubber to obtain component A;

[0063] (3) 85 parts of base rubber, 10 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl content of 0.1%, 5 parts of hydrogenated silicone oil with a hydrogen content of 1.6%, and 0.01 parts of a silicone inhibitor were mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there were no obvious bubbles in the rubber, to obtain component B;

[0064] (4) Component A and component B are mixed in a vacuum at a weight ratio of 1:1 to obtain a rubber compound.

[0065] Example 2

[0066] (1) 60 parts of vinyl silicone oil with a viscosity of 20,000 mPa·s and a vinyl content of 0.08% were added to a vacuum kneader, and 5 parts of hexamethyldisilazane, 1 part of dimethylvinylethoxysilane and 2 parts of pure water were added and mixed evenly. A total of 40 parts of a specific surface area of ​​150 m 2 / g of high-performance, highly dispersed precipitated silica, kneading at room temperature for 100 minutes, turning on the heating mode, turning on the vacuum equipment after reaching the target temperature of 180 degrees Celsius, kneading for 100 minutes under vacuum heating, adding 40 parts of vinyl silicone oil with a viscosity of 20000mPa·s and a vinyl mass content of 0.08% to dilute the rubber, and continue kneading for 100 minutes under vacuum to obtain a base rubber for standby use;

[0067] (2) 75 parts of base rubber, 20 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl content of 0.1%, 20 parts of a composite oil-resistant additive (the mass ratio of the components is diatomaceous earth: cerium oxide: calcium silicate = 2:2:6), 0.5 parts of a structure control agent, and 0.05 parts of a 3000 ppm platinum catalyst are mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there are no obvious bubbles in the rubber to obtain component A;

[0068] (3) 85 parts of base rubber, 10 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl mass content of 0.1%, 5 parts of hydrogenated silicone oil with a hydrogen content of 1.6%, and 0.01 parts of a silicone inhibitor were mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there were no obvious bubbles in the rubber, thereby obtaining component B;

[0069] (4) Component A and component B are mixed in a vacuum at a weight ratio of 1:1 to obtain a rubber compound.

[0070] Example 3

[0071] (1) 60 parts of vinyl silicone oil with a viscosity of 20,000 mPa·s and a vinyl content of 0.08% were added to a vacuum kneader, and 20 parts of hexamethyldisilazane, 5 parts of dimethylvinylethoxysilane and 5 parts of pure water were added and mixed evenly. A total of 40 parts of a specific surface area of ​​150 m 2 / g of high-performance, highly dispersed precipitated silica, kneading at room temperature for 100 minutes, turning on the heating mode, turning on the vacuum equipment after reaching the target temperature of 180 degrees Celsius, kneading for 100 minutes under vacuum heating, adding 40 parts of vinyl silicone oil with a viscosity of 20000mPa·s and a vinyl mass content of 0.08% to dilute the rubber, and continue kneading for 100 minutes under vacuum to obtain a base rubber for standby use;

[0072] (2) 75 parts of base rubber, 20 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl content of 0.1%, 20 parts of a composite oil-resistant additive (the mass ratio of the components is diatomaceous earth: cerium oxide: calcium silicate = 2:2:6), 0.5 parts of a structure control agent, and 0.05 parts of a 3000 ppm platinum catalyst are mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there are no obvious bubbles in the rubber to obtain component A;

[0073] (3) 85 parts of base rubber, 10 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl mass content of 0.1%, 5 parts of hydrogenated silicone oil with a hydrogen content of 1.6%, and 0.01 parts of a silicone inhibitor were mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there were no obvious bubbles in the rubber, thereby obtaining component B;

[0074] (4) Component A and component B are mixed in a vacuum at a weight ratio of 1:1 to obtain a rubber compound.

[0075] Example 4

[0076] (1) 60 parts of vinyl silicone oil with a viscosity of 20,000 mPa·s and a vinyl content of 0.08% were added to a vacuum kneader, and 10 parts of hexamethyldisilazane, 3 parts of dimethylvinylethoxysilane and 3 parts of pure water were added and mixed evenly. A total of 40 parts of a specific surface area of ​​150 m 2 / g of high-performance, highly dispersed precipitated silica, kneading at room temperature for 100 minutes, turning on the heating mode, turning on the vacuum equipment after reaching the target temperature of 180 degrees Celsius, kneading for 100 minutes under vacuum heating, adding 40 parts of vinyl silicone oil with a viscosity of 20000mPa·s and a vinyl mass content of 0.08% to dilute the rubber, and continuing to knead for 100 minutes under vacuum to obtain a base rubber for standby use;

[0077] (2) 75 parts of base rubber, 20 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl content of 0.1%, 30 parts of a composite oil-resistant additive (the mass ratio of the components is diatomaceous earth: cerium oxide: calcium silicate = 2:2:6), 0.5 parts of a structure control agent, and 0.05 parts of a 3000 ppm platinum catalyst were mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there were no obvious bubbles in the rubber, to obtain component A;

[0078] (3) 85 parts of base rubber, 10 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl mass content of 0.1%, 5 parts of hydrogenated silicone oil with a hydrogen content of 1.6%, and 0.01 parts of a silicone inhibitor were mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there were no obvious bubbles in the rubber, thereby obtaining component B;

[0079] (4) Component A and component B are mixed in a vacuum at a weight ratio of 1:1 to obtain a rubber compound.

[0080] Example 5

[0081] (1) 60 parts of vinyl silicone oil with a viscosity of 20,000 mPa·s and a vinyl content of 0.08% were added to a vacuum kneader, and 10 parts of hexamethyldisilazane, 3 parts of dimethylvinylethoxysilane and 3 parts of pure water were added and mixed evenly. A total of 40 parts of a specific surface area of ​​150 m 2 / g of high-performance, highly dispersed precipitated silica, kneading at room temperature for 100 minutes, turning on the heating mode, turning on the vacuum equipment after reaching the target temperature of 180 degrees Celsius, kneading for 100 minutes under vacuum heating, adding 40 parts of vinyl silicone oil with a viscosity of 20000mPa·s and a vinyl mass content of 0.08% to dilute the rubber, and continuing to knead for 100 minutes under vacuum to obtain a base rubber for standby use;

[0082] (2) 75 parts of base rubber, 20 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl content of 0.1%, 10 parts of a composite oil-resistant additive (the mass ratio of the components is diatomaceous earth: cerium oxide: calcium silicate = 2:2:6), 0.5 parts of a structure control agent, and 0.05 parts of a 3000 ppm platinum catalyst were mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there were no obvious bubbles in the rubber, to obtain component A;

[0083] (3) 85 parts of base rubber, 10 parts of vinyl silicone oil with a viscosity of 10000 mPa·s and a vinyl mass content of 0.1%, 5 parts of hydrogenated silicone oil with a hydrogen content of 1.6%, and 0.01 parts of a silicone inhibitor were mixed and stirred manually for 5 minutes, and then vacuumed for 10 minutes until there were no obvious bubbles in the rubber, thereby obtaining component B;

[0084] (4) Component A and component B are mixed in a vacuum at a weight ratio of 1:1 to obtain a rubber compound.

[0085] Example 6

[0086] Compared with Example 1, step (2) comprises a composite oil-resistant additive (the mass ratio of the components is diatomaceous earth: cerium oxide: calcium silicate = 1:3:5), and the rest is the same as Example 1.

[0087] Example 7

[0088] Compared with Example 1, step (2) is to prepare a composite oil-resistant additive (the mass ratio of the components is diatomaceous earth: cerium oxide: calcium silicate = 3:1:7), and the rest is the same as Example 1.

[0089] Comparative Example 1

[0090] Compared with Example 1, the difference is that: in step (2), no composite oil-resistant additive is added, and the rest is the same as Example 1.

[0091] Comparative Example 2

[0092] Compared with Example 1, the difference is that: in step (2), 40 parts of composite oil-resistant additive (the component ratio is diatomaceous earth: cerium oxide: calcium silicate = 2:2:6) are added, and the rest is the same as Example 1.

[0093] Comparative Example 3

[0094] Compared with Example 1, the difference is that in step (2), 5 parts of composite oil-resistant additive (the component ratio is diatomaceous earth: cerium oxide: calcium silicate = 2:2:6) are added, and the rest is the same as Example 1.

[0095] Comparative Example 4

[0096] Compared with Example 1, the difference is that: in step (2), 20 parts of oil-resistant additive (component is calcium silicate) are added, and the rest is the same as Example 1.

[0097] Comparative Example 5

[0098] Compared with Example 1, the difference is that in step (2), 20 parts of oil-resistant additive (component is cerium oxide) are added, and the rest is the same as Example 1.

[0099] Comparative Example 6

[0100] Compared with Example 1, the difference is that in step (2), 20 parts of oil-resistant additive (component is diatomaceous earth) are added, and the rest is the same as Example 1.

[0101] Comparative Example 7

[0102] Compared with Example 1, the difference is that the reinforcing filler used in step (1) is a commercially available conventional 150m 2 / g of precipitated silica, and the rest is the same as in Example 1.

[0103] Test Example 1

[0104] (1) The rubber materials obtained in Examples 1 to 7 and Comparative Examples 1 to 7 were made into standard specimens at 130° C. for 5 min, and hardness test, tensile strength test, tear strength test and elongation at break test were performed (refer to standard GBT528-2009).

[0105] (2) The rubber materials obtained in Examples 1 to 7 and Comparative Examples 1 to 7 were made into standard specimens at 130° C. for 5 min. The mechanical properties and volume change rate of the specimens after immersion in 903 oil at 150° C. for 120 h were tested according to ASTM D471 (referring to GBT1690-2010).

[0106] The properties of the silicone rubber obtained in Examples 1 to 7 and Comparative Examples 1 to 7 are shown in Table 1 and Table 2.

[0107] Table 1 Silicone rubber performance test results

[0108] sample Hardness shoreA Tensile strengthMpa Elongation at break % Tear strength KN / m Example 1 43 5.7 370 14.6 Example 2 42 5.5 366 14.4 Example 3 43 5.8 357 14 Example 4 45 4.8 320 11.7 Example 5 42 6 353 14.8 Example 6 43 5.4 311 12.1 Example 7 42 5.5 339 13.5 Comparative Example 1 40 6.8 524 15.7 Comparative Example 2 47 4.2 311 12.5 Comparative Example 3 41 6.1 344 14.3 Comparative Example 4 43 5.2 329 12.6 Comparative Example 5 43 5.1 328 12 Comparative Example 6 42 6.9 522 15.4 Comparative Example 7 43 5.2 330 13.2

[0109] Table 2 Silicone rubber oil immersion test performance change results

[0110]

[0111]

[0112] Comprehensive data from Tables 1 and 2 show that Example 1 is the best (medium to high mechanical properties, medium to high oil resistance); Example 2 uses too little surface treatment agent (mechanical properties are slightly weaker, and oil resistance is close to Example 1); Example 3 uses too much surface treatment agent (mechanical properties are similar to Example 1, but there is no obvious improvement, high cost, and oil resistance is close to Example 1); Example 4 The composite oil-resistant additive is 30 parts (hardness increases, mechanical properties decrease significantly, and oil resistance is not significantly improved); Example 5 The composite oil-resistant additive is 10 parts (mechanical properties decrease less, but oil resistance is poor); Example 6 The composite oil-resistant additive has a higher proportion of cerium oxide compared to Example 1 (cerium oxide causes a significant decrease in mechanical properties, but the oil resistance is close to Example 1); Example 7 The composite oil-resistant additive has a lower proportion of cerium oxide compared to Example 1, and the proportion of diatomaceous earth and calcium silicate components is increased (mechanical properties have no significant change compared to Example 1, oil resistance Performance deteriorates); Comparative Example 1 has no oil-resistant additive (the best mechanical properties, but the worst oil resistance); Comparative Example 2 has 40 parts of composite oil-resistant additive (the more the amount, the higher the hardness, the more obvious the decline in mechanical properties, but the oil resistance is indeed improved, but the normal required mechanical properties are lost; Comparative Example 3 has 5 parts of composite oil-resistant additive (better mechanical properties than Example 1, but poor oil resistance, worse than Example 5); Comparative Example 4 The oil-resistant additive is calcium silicate (compared with Example 1, the performance is slightly lower, and the oil resistance is not good enough); Comparative Example 5 The oil-resistant additive is cerium oxide (compared with Example 1, the mechanical properties are significantly reduced, but the oil resistance is slightly better); Comparative Example 6 The oil-resistant additive is diatomaceous earth (compared with no addition, the strength is slightly improved, but there is basically no oil resistance, which is slightly better than no addition); Comparative Example 7 uses commercially available conventional precipitated silica as a reinforcing material, and the rest is the same as Example 1 (the overall mechanical properties are worse than Example 1, and the oil resistance is similar).

[0113] From the data of Examples 1 to 3 in Tables 1 and 2 above, it can be seen that hexamethyldisilazane and dimethylvinylethoxysilane can further treat precipitated silica to improve the strength of liquid silicone rubber, but this measure has no obvious effect on improving the oil resistance of liquid silicone rubber.

[0114] It can be seen from the data of Example 1 and Comparative Examples 4-5 in Table 1 and Table 2 above that when calcium silicate is used alone as an oil-resistant additive, it has a certain oil resistance, but it is poorer than the compound oil-resistant additive; when cerium oxide is used alone as an oil-resistant additive, although it has good oil resistance, the performance of silicone rubber decreases too much; and when diatomaceous earth is used alone as an oil-resistant additive, the hardness of silicone rubber increases slightly, some mechanical properties are improved, but the oil resistance is general.

[0115] From the data of Example 1, Examples 4 to 5, and Comparative Examples 1 to 3 in Table 1 and Table 2 above, it can be seen that when no composite oil-resistant additive is added, the tensile strength and elongation at break are greatly reduced after the oil immersion test, and the volume change rate is high; Example 4, Example 5, Comparative Example 2, and Comparative Example 3 respectively add different amounts of composite oil-resistant additives. Although they have certain oil resistance, excessive addition will cause the mechanical properties of the silicone rubber itself to drop significantly, while too little addition will result in insufficient oil resistance. The more suitable addition amount of the composite oil-resistant additive is in the range of 10 to 30 parts.

[0116] Test Example 2

[0117] Use a putty consistency tester to test the adhesives obtained in Example 1, Comparative Example 1 and Comparative Example 7. Fill the pump with the sample (without leaving any gaps) and then use the pump plug to press the sample out of the pump. Cut the cylindrical sample with a paint knife and place it in the center of the glass plate. Start a stopwatch at the same time. After 5 minutes, observe the scale on the coordinate paper on which the sample freely flows and spreads on the glass plate, record its diameter in centimeters, and test its fluidity. The test results are shown in Table 3.

[0118] Table 3 Rubber fluidity test results

[0119] Serial number sample Leveling diameter(cm) 1 Example 1 9.9 2 Comparative Example 1 10.8 3 Comparative Example 7 8.5

[0120] From the data in Table 1, Table 2 and Table 3, it can be seen that adding a certain amount of compound oil-resistant additives will lead to poor fluidity of liquid silicone rubber. The reinforcing filler used in Comparative Example 7 is commercially available ordinary precipitated silica, which is different from the high-performance and highly dispersed precipitated silica used in Comparative Example 7. Compared with Example 1 of the present invention, the mechanical properties and fluidity of the liquid silicone rubber obtained in Example 1 are better than those in Comparative Example 7. Compared with other examples, Example 1 has better oil resistance and mechanical properties, and is the best example of the present invention. Therefore, the oil-resistant addition-type liquid silicone rubber prepared by the preparation method of the present invention has better mechanical properties, oil resistance and fluidity.

[0121] In summary, the present invention significantly improves the oil resistance of addition-type liquid silicone rubber in an oil-immersed environment by adding a compounded oil-resistant additive, and also uses the high-performance and highly dispersed precipitated silica developed by the applicant in the early stage. As reinforcing fillers, the addition-type liquid silicone rubber has excellent mechanical properties and fluidity. Compared with traditional solid oil-resistant silicone rubber, it has higher production efficiency and wider application scenarios.

Claims

1. An addition type liquid silicone rubber composition, characterized in that: It comprises component A and component B of equal mass; The component A comprises the following raw materials in parts by weight: 70-80 parts of base rubber, 18-22 parts of vinyl silicone oil, 10-30 parts of compound oil-resistant additive, and 0.01-0.1 parts of catalyst; The component B comprises the following raw materials in parts by weight: 80-90 parts of base rubber, 8-12 parts of vinyl silicone oil, and 4-6 parts of hydrogenated silicone oil; The base rubber in component A and component B includes the following raw materials in parts by weight: 90 to 110 parts of vinyl silicone oil, 35 to 45 parts of a specific surface area of ​​100 to 200 m 2 / g high performance and highly dispersed precipitated silica C368; The compound oil-resistant additive is diatomaceous earth, cerium oxide and calcium silicate, and the mass ratio thereof is 1-3:1-3:5-7.

2. The addition type liquid silicone rubber composition according to claim 1, characterized in that: The component A also includes 0.1 to 1 part of a structure control agent.

3. The addition type liquid silicone rubber composition according to claim 1, characterized in that: The component B also includes 0.01 to 0.1 parts of a silica gel inhibitor.

4. The addition type liquid silicone rubber composition according to claim 1, characterized in that: The base glue also includes 5 to 20 parts of hexamethyldisilazane, 1 to 5 parts of dimethylvinylethoxysilane and 1 to 5 parts of pure water.

5. The addition type liquid silicone rubber composition according to claim 1, characterized in that: The viscosity of the vinyl silicone oil is 500-100000 mPa·s, and the mass content of vinyl is 0.06-3.0%.

6. The addition type liquid silicone rubber composition according to claim 1, characterized in that: The hydrogen-containing silicone oil includes polydimethylhydrogensiloxane containing Si-H in the side chain and polydimethylhydrogensiloxane containing Si-H at both ends and in the side chain; wherein the hydrogen content of the polydimethylhydrogensiloxane is 0.1-2.0%.

7. A method for preparing an addition type liquid silicone rubber, characterized in that: The component A and the component B of the addition type liquid silicone rubber composition according to any one of claims 1 to 6 are mixed and mixed in vacuum to obtain the addition type liquid silicone rubber compound.

8. The preparation method according to claim 7, characterized in that: The preparation method of the component A is to add vinyl silicone oil, a compound oil-resistant additive, a structure control agent and a catalyst into the base rubber, and mix them in vacuum to obtain the component A.

9. The preparation method according to claim 7, characterized in that: The preparation method of the component B is to add vinyl silicone oil, hydrogen-containing silicone oil and silica gel inhibitor into the base rubber, and mix them in vacuum to obtain the component B.

10. The preparation method according to claim 7, characterized in that: The preparation method of the base rubber is as follows: firstly, 50-70% of vinyl silicone oil, high-performance and highly dispersed precipitated silica, hexamethyldisilazane, dimethylvinylethoxysilane and pure water are mixed, and vacuum heating and kneading are performed, and then the remaining 30%-50% of vinyl silicone oil is added for dilution, and vacuum heating and kneading are performed to obtain the base rubber.

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