Tear-resistant silicone rubber and preparation method thereof

Abstract

The invention relates to tear-resistant silicone rubber and a preparation method thereof. The tear-resistant silicone rubber comprises the following components: hydroxyl-terminated polydimethylsiloxane serving as base rubber, boric acid, high vinyl silicone oil, dimethyl silicone oil, filler, a structured control agent, an accelerant and a heat-resistant additive. The preparation method comprises the following steps: mixing high vinyl silicone oil with dimethyl silicone oil, reacting hydroxyl-terminated polydimethylsiloxane with boric acid at 20-30 DEG C to obtain polyboron-containing dimethyl siloxane, blending the two solutions, adding into a high-speed dispersion machine, adding the filler, zinc oxide and the structured control agent, stirring, controlling the temperature of the material to be 20-40 DEG C, and carrying out uniform mixing to obtain the polyboron-containing dimethyl siloxane. The preparation method comprises the following steps: reacting for 2 hours, then dehydrating for 2 hours to obtain a preformed silica gel material, then adding zinc 1, 5-pentylidene dithiocarbamate and zinc oxide, and then carrying out vulcanization molding and cooling to obtain the high-tear-resistance silicone rubber product.

Description

Technical Field

[0001] The invention relates to the preparation of silicone rubber materials, in particular to tear-resistant silicone rubber and a preparation method thereof. Background Art

[0002] Silicone rubber refers to a type of elastomer with an inorganic structure of -Si-O- in the main chain of the molecule and an organic group in the side chain. It has excellent weather resistance, adhesion, good heat resistance, aging resistance, cold resistance and electrical insulation. It is easy to apply and is suitable for a wide range of substrates. It is currently widely developed and used in door and window building decoration, traffic bridge waterproofing, electronic and electrical bonding, home furnishing and furniture caulking, as well as chemical, military and other national economic fields. There are three types of silicone rubber: deketoxime type, deacidification type and dealcoholization type. Among them, the dealcoholization type silicone sealant has the characteristics of low corrosion, no irritating odor, cleaner and more environmentally friendly, and good adhesion to aluminum, glass and other substrates, and is welcomed by the majority of users.

[0003] However, due to its chemical structure, the mechanical strength of silicone rubber is lower than that of natural rubber. In order to further improve the mechanical strength of silicone rubber, especially the tear strength, it becomes increasingly important. In addition, even if some silicone rubbers have high tear strength, their mechanical properties will gradually decrease during the use of silicone rubber products due to the influence of ambient temperature. Therefore, improving the tear strength of silicone rubber and maintaining the corresponding high tear performance at higher temperatures has become one of the important research directions.

[0004] Therefore, it is necessary to develop a silicone rubber with good thermal stability and high tear strength and a preparation method thereof. Summary of the invention

[0005] In view of the deficiencies of the prior art, the primary purpose of the present invention is to prepare a tear-resistant silicone rubber and a preparation method thereof, which are mainly used to improve the tear resistance of rubber materials.

[0006] To achieve the above-mentioned purpose, the present invention proposes a tear-resistant silicone rubber, comprising: 90-100 parts by weight of terminal hydroxyl polydimethylsiloxane as a base rubber, 0.5-2 parts by weight of boric acid, 0.5-5 parts by weight of high vinyl silicone oil, 5-30 parts by weight of dimethyl silicone oil, 30-70 parts by weight of filler, 3-8 parts by weight of a structuring control agent, 1-5 parts by weight of an accelerator, and 0.5-3 parts by weight of a heat-resistant additive.

[0007] The accelerator is zinc 1,5-pentylidene dithiocarbamate.

[0008] The heat-resistant additive is zinc oxide.

[0009] Preferably, the filler is fumed silica.

[0010] Preferably, the structuring control agent is any one or more of dimethyldimethoxysilane, hexamethyldisilazane, vinyldisilazane and / or hydroxy silicone oil.

[0011] Preferably, the method for preparing the tear-resistant silicone rubber comprises the following steps:

[0012] (1) High vinyl silicone oil and dimethyl silicone oil are mixed in a mass ratio of 1:5-10 to obtain a mixed solution A.

[0013] (2) reacting terminal hydroxyl polydimethylsiloxane and boric acid at 20-30° C. to obtain polyborodimethylsiloxane, and blending the polyborodimethylsiloxane solution with mixed solution A to obtain a boron-oxygen bond-containing mixed solution B.

[0014] (3) Add the mixed solution B to the high-speed disperser, add 50-70 parts by weight of filler in 3 batches, add zinc oxide additive and structuring control agent, then start high-speed stirring to increase the temperature to 120°C and the stirring speed to 1200-1400 / r·min -1 After stirring for 5-10 minutes, control the material temperature at 20-40℃, and then 1100-1300 / r·min -1 After stirring for 20-30 minutes, open the vacuum valve and dehydrate for 2 hours to obtain a preformed silica gel material.

[0015] (4) Add zinc 1,5-pentylidene dithiocarbamate to zinc oxide to obtain a zinc 1,5-pentylidene dithiocarbamate solution containing zinc groups.

[0016] (5) adding the solution of step (4) to the preformed silicone material of step (3) for calendering, and then vulcanizing and cooling to obtain a high tear-resistant silicone rubber product.

[0017] Preferably, the mixing temperature in step (1) is 30-100°C and the stirring speed is 500-800 / r·min -1 .

[0018] Preferably, the material temperature in step (3) is 26°C.

[0019] Preferably, the reaction temperature in step (4) is 100-150°C.

[0020] Preferably, the material-liquid ratio in step (5) is 90-150:1; the vulcanization molding temperature is 120-130° C., and the vulcanization molding time is 5-10 min.

[0021] Beneficial effects: (1) The present invention utilizes high vinyl silicone oil and dimethyl silicone oil to blend in a certain proportion to improve the fluidity, formability and elasticity of silicone rubber, thereby effectively improving the performance of silicone rubber products. In step (2), polyboron dimethyl siloxane is synthesized with hydroxyl-terminated polydimethyl siloxane and boric acid, and the boron atom forms a boron / oxygen bond with the adjacent oxygen atom, thereby generating a cross-linked network. At the same time, the reaction process is carried out under low temperature conditions. The silicone rubber bonding mechanical effect of dealcoholized silicone rubber prepared under high temperature conditions will be much worse than that prepared by low temperature processes, because after cross-linking at high temperature, a three-dimensional network structure with high cross-linking density and easy to crack when stretched will be formed during the water reaction process. Therefore, controlling the temperature at 20-30°C can significantly improve the tear resistance of silicone rubber.

[0022] (2) The use of zinc 1,5-pentylidene dithiocarbamate can not only increase the density of the cross-linking bonds and the effect of stress homogenization, but also increase the vulcanization rate during the vulcanization process. At the same time, zinc 1,5-pentylidene dithiocarbamate has a unique structure and properties, a high melting point, is not easy to decompose at high temperatures, and has very good stability.

[0023] In step (4), a zinc ion coordination complex is obtained by introducing a 1,5-pentamethylenedithiocarbamate zinc solution containing zinc metal particles. The ion coordination complex can significantly improve its solubility in rubber, and the increase in solubility helps to improve the uniformity of the silicone rubber system. At the same time, the coordination complex formed in step (4) attracts the ZnO particles, so that the coordination complex produced by the reaction is adsorbed on the rubber surface. Due to the increase in rubber solubility, ZnO is more easily encapsulated by rubber, thereby significantly increasing the contact between the rubber and the active coordination complex, thereby improving the reaction efficiency and tear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a reaction flow chart of the highly tear-resistant silicone rubber prepared in Example 1. DETAILED DESCRIPTION

[0025] The invention provides a tear-resistant silicone rubber with good thermal stability and a preparation method thereof, which are used to solve the technical problem in the prior art that the tear strength of silicone rubber needs to be improved.

[0026] The technical solution of the present application will be described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0027] Except for those with indicated sources, all other substances used in the following examples are commercially available.

[0028] Example 1

[0029] A method for preparing tear-resistant silicone rubber comprises the following steps:

[0030] (1) High vinyl silicone oil and dimethyl silicone oil are mixed in a mass ratio of 1:5 to obtain a mixed solution A.

[0031] (2) The terminal hydroxyl polydimethylsiloxane and boric acid are reacted at 26° C. to obtain polyborodimethylsiloxane, and the polyborodimethylsiloxane solution is blended with the mixed solution A to obtain a mixed solution B containing boron oxygen bonds.

[0032] (3) Add the boron-oxygen bond mixed solution B to a high-speed disperser, add 20 parts by weight of fumed silica in three batches, add zinc oxide additive, and structure control agent dimethyldimethoxysilane, then start high-speed stirring to increase the temperature to 120°C and the stirring speed to 1200 / r·min -1 After stirring for 8 minutes, the material temperature was controlled at 22°C and then the -1 After stirring for 25 minutes, open the vacuum valve and dehydrate for 2 hours to obtain a preformed silica gel material.

[0033] (4) Add zinc oxide to 1,5-pentylidene dithiocarbamate and react at a temperature of 120° C. to obtain a zinc 1,5-pentylidene dithiocarbamate solution containing a zinc group.

[0034] (5) adding the solution of step (4) to the preformed silicone material of step (3) at a material-liquid ratio of 90:1 for calendering, and then vulcanizing and cooling. The vulcanization temperature is 120° C. and the vulcanization time is 5 min to obtain a high tear-resistant silicone rubber product.

[0035] Example 2

[0036] A method for preparing tear-resistant silicone rubber comprises the following steps:

[0037] (1) High vinyl silicone oil and dimethyl silicone oil are mixed in a mass ratio of 1:10 to obtain a mixed solution A.

[0038] (2) The terminal hydroxyl polydimethylsiloxane and boric acid are reacted at 30° C. to obtain polyborodimethylsiloxane, and the polyborodimethylsiloxane solution is blended with the mixed solution A to obtain a boron-oxygen bond-containing mixed solution B.

[0039] (3) Add the mixed solution B to the high-speed disperser, add 25 parts by weight of filler in 3 batches, add zinc oxide additive and structure control agent, and then start high-speed stirring to increase the temperature to 120°C and the stirring speed to 1400 / r·min -1 After stirring for 10 minutes, the material temperature was controlled at 40°C and then 1300 / r·min-1 After stirring for 30 minutes, open the vacuum valve and dehydrate for 2 hours to obtain a preformed silica gel material.

[0040] (4) Add zinc 1,5-pentylidene dithiocarbamate to zinc oxide to obtain a zinc 1,5-pentylidene dithiocarbamate solution containing zinc groups.

[0041] (5) adding the solution of step (4) to the preformed silicone material of step (3) at a material-liquid ratio of 100:1 for calendering, and then vulcanizing and cooling. The vulcanization temperature is 120° C. and the vulcanization time is 5 min to obtain a high tear-resistant silicone rubber product.

[0042] Example 3

[0043] A method for preparing tear-resistant silicone rubber comprises the following steps:

[0044] (1) High vinyl silicone oil and dimethyl silicone oil are mixed in a mass ratio of 1:8 to obtain a mixed solution A.

[0045] (2) The terminal hydroxyl polydimethylsiloxane and boric acid are reacted at 26° C. to obtain polyborodimethylsiloxane, and the polyborodimethylsiloxane solution is blended with the mixed solution A to obtain a mixed solution B containing boron oxygen bonds.

[0046] (3) Add the mixed solution B to the high-speed disperser, add 25 parts by weight of filler in 3 batches, add zinc oxide additive and structure control agent, and then start high-speed stirring to increase the temperature to 120°C and the stirring speed to 1300 / r·min -1 After stirring for 8 minutes, the material temperature was controlled at 25°C and then the speed was 1200 / r·min -1 After stirring for 25 minutes, open the vacuum valve and dehydrate for 2 hours to obtain a preformed silica gel material.

[0047] (4) Add zinc 1,5-pentylidene dithiocarbamate to zinc oxide to obtain a zinc 1,5-pentylidene dithiocarbamate solution containing zinc groups.

[0048] (5) adding the solution of step (4) to the preformed silicone material of step (3) for calendering, and then vulcanizing and cooling to obtain a high tear-resistant silicone rubber product.

[0049] Comparative Example 1

[0050] A method for preparing tear-resistant silicone rubber comprises the following steps:

[0051] (1) High vinyl silicone oil and dimethyl silicone oil are mixed in a mass ratio of 1:5 to obtain a mixed solution A.

[0052] (2) The terminal hydroxyl polydimethylsiloxane and boric acid are reacted at 100° C. to obtain polyborodimethylsiloxane, and the polyborodimethylsiloxane solution is blended with the mixed solution A to obtain a boron-oxygen bond-containing mixed solution B.

[0053] (3) Add the mixed solution B to the high-speed disperser, add 20 parts by weight of filler in 3 batches, add zinc oxide additive and structure control agent, and then start high-speed stirring to increase the temperature to 120°C and the stirring speed to 1200 / r·min. -1 After stirring for 5 minutes, the material temperature was controlled at 20°C and then 1100 / r·min -1 After stirring for 20 minutes, open the vacuum valve and dehydrate for 2 hours to obtain a preformed silica gel material.

[0054] (4) Add zinc 1,5-pentylidene dithiocarbamate to zinc oxide to obtain a zinc 1,5-pentylidene dithiocarbamate solution containing zinc groups.

[0055] (5) adding the solution of step (4) to the preformed silicone material of step (3) for calendering, and then vulcanizing and cooling to obtain a high tear-resistant silicone rubber product.

[0056] Comparative Example 2

[0057] A method for preparing tear-resistant silicone rubber comprises the following steps:

[0058] (1) High vinyl silicone oil and dimethyl silicone oil are mixed in a mass ratio of 1:10 to obtain a mixed solution A.

[0059] (2) Add the mixed solution A and the hydroxy-terminated polydimethylsiloxane into a high-speed disperser, add 30 parts by weight of filler in three batches, add zinc oxide additive and structure control agent, and then start high-speed stirring to increase the temperature to 120°C and the stirring speed to 1400 / r·min. -1 After stirring for 10 minutes, the material temperature was controlled at 40°C and then 1300 / r·min -1 After stirring for 30 minutes, open the vacuum valve and dehydrate for 2 hours to obtain a preformed silica gel material.

[0060] (4) Add zinc 1,5-pentylidene dithiocarbamate to zinc oxide to obtain a zinc 1,5-pentylidene dithiocarbamate solution containing zinc groups.

[0061] (5) adding the solution of step (4) to the preformed silicone material of step (3) for calendering, and then vulcanizing and cooling to obtain a silicone rubber product.

[0062] Comparative Example 3

[0063] A method for preparing tear-resistant silicone rubber comprises the following steps:

[0064] (1) High vinyl silicone oil and dimethyl silicone oil are mixed in a mass ratio of 1:8 to obtain a mixed solution A.

[0065] (2) The terminal hydroxyl polydimethylsiloxane and boric acid are reacted at 25° C. to obtain polyborodimethylsiloxane, and the polyborodimethylsiloxane solution is blended with the mixed solution A to obtain a boron-oxygen bond-containing mixed solution B.

[0066] (3) Add the mixed solution B to the high-speed disperser, add 25 parts by weight of filler in 3 batches, add zinc oxide additive and structure control agent, and then start high-speed stirring to increase the temperature to 120°C and the stirring speed to 1300 / r·min -1 After stirring for 8 minutes, control the material temperature at 20-40°C and then 1100-1300 / r·min -1 After stirring for 20-30 minutes, open the vacuum valve and dehydrate for 2 hours to obtain a preformed silica gel material.

[0067] (4) The silicone material preformed in step (3) is subjected to calendering, and then subjected to vulcanization, molding, and cooling to obtain a silicone rubber product.

[0068] Table 1 Performance test results

[0069] Tear strength (KN / m) Tensile strength(MPa) Elongation at break (%) Hardness (Shore A) Example 1 70 38 720 53 Example 2 65 36 703 58 Example 3 68 35 698 54 Comparative Example 1 41 27 561 54 Comparative Example 2 46 25 570 50 Comparative Example 3 39 28 545 53

[0070] Conclusion: From the performance test data in Table 1, it can be seen that according to Comparative Example 1 of the present invention, the performance of the silicone rubber product obtained by reacting the terminal hydroxyl polydimethylsiloxane with boric acid at high temperature is relatively low. Comparative Example 2 does not add step (2) of boric acid for reaction, resulting in low performance of the silicone rubber product, especially in terms of tear resistance. Comparative Example 3 does not add step (4) of 1,5-pentylenedithiocarbamate zinc and zinc oxide, resulting in low performance of the silicone rubber product, especially in terms of tear resistance and elongation at break.

[0071] The above is a detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the described embodiments. For ordinary technicians in this field, without departing from the concept of the present invention, several changes, modifications, substitutions and variations are made to these embodiments, which still fall within the protection scope of the present invention.

Claims

1. A tear-resistant silicone rubber, characterized in that: include: 90-100 parts by weight of terminal hydroxyl polydimethylsiloxane as base glue, 0.5-2 parts by weight of boric acid, 0.5-5 parts by weight of high vinyl silicone oil, 5-30 parts by weight of dimethyl silicone oil, 30-70 parts by weight of filler, 3-8 parts by weight of structuring control agent, 1-5 parts by weight of accelerator, and 0.5-3 parts by weight of heat-resistant auxiliary agent; The accelerator is zinc 1,5-pentylidene dithiocarbamate; The heat-resistant auxiliary agent is a zinc oxide auxiliary agent.

2. The tear-resistant silicone rubber according to claim 1, characterized in that: The filler is fumed silica.

3. The tear-resistant silicone rubber according to claim 1, characterized in that: The structure control agent is any one or more of dimethyldimethoxysilane, hexamethyldisilazane, vinyldisilazane and / or hydroxy silicone oil.

4. The method for preparing tear-resistant silicone rubber according to claim 1, characterized in that: The following steps are involved: (1) mixing high vinyl silicone oil and dimethyl silicone oil in a mass ratio of 1:5-10 to obtain a mixed solution A; (2) reacting terminal hydroxyl polydimethylsiloxane and boric acid at 20-30° C. to obtain polyborodimethylsiloxane, and blending the polyborodimethylsiloxane solution with the mixed solution A to obtain a boron-oxygen bond-containing mixed solution B; (3) Add the mixed solution B to the high-speed disperser, add 50-70 parts by weight of filler in 3 batches, add zinc oxide additive and structuring control agent, then start high-speed stirring to increase the temperature to 120°C and the stirring speed to 1200-1400 / r·min -1 After stirring for 5-10 minutes, control the material temperature at 20-40℃, and then 1100-1300 / r·min -1 After stirring for 20-30 minutes, open the vacuum valve and dehydrate for 2 hours to obtain a preformed silica gel material; (4) adding zinc 1,5-pentylidene dithiocarbamate to zinc oxide to obtain a zinc 1,5-pentylidene dithiocarbamate solution containing a zinc group; (5) adding the solution of step (4) to the preformed silicone material of step (3) for calendering, and then vulcanizing and cooling to obtain a high tear-resistant silicone rubber product.

5. The method for preparing tear-resistant silicone rubber according to claim 4, characterized in that: The mixing temperature in step (1) is 30-100°C and the stirring speed is 500-800 / r·min -1 .

6. The method for preparing tear-resistant silicone rubber according to claim 4, characterized in that: In step (3), the material temperature is controlled to be 26°C.

7. The method for preparing tear-resistant silicone rubber according to claim 4, characterized in that: The reaction temperature in step (4) is 100-150°C.

8. The method for preparing tear-resistant silicone rubber according to claim 4, characterized in that: In step (5), the material-liquid ratio is 90-150:1; the vulcanization molding temperature is 120-130° C., and the vulcanization molding time is 5-10 minutes.

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