A method for chain modification of solution polymerized styrene-butadiene rubber and its use

Abstract

This invention provides a method for in-chain modification of solution-polymerized styrene-butadiene rubber (SBR) and its application. The modification method includes the following steps: S1, mixing styrene monomers and butadiene, solvent toluene, and a polar modifier, single-ended hydrogen-containing silicone oil, and adding an alkyl lithium initiator for reaction; S2, adding a platinum catalyst to the product obtained in S1 for reaction; S3, precipitating the product in S2 using methanol as a precipitant, filtering, and drying. This method uses single-ended hydrogen-containing silicone oil as a polarity modifier to prepare randomized SBR. After the reaction, the single-ended hydrogen-containing silicone oil is added to the raw rubber chain via hydrosilylation, changing the polarity of the raw rubber, improving the interfacial bonding force between SBR and filler silica, and making the filler more uniformly dispersed in the rubber compound, thereby improving the mechanical properties and wet skid resistance of the rubber and reducing its rolling resistance.

Description

Technical Field

[0001] This invention relates to the field of styrene-butadiene rubber (SBR) synthesis, and more specifically, to a method for in-chain modification of randomized solution-polymerized SBR, the resulting solution-polymerized SBR being an excellent tire material. Background Technology

[0002] With the rapid development of new energy vehicles, people have higher requirements for tires, demanding not only good wear resistance but also good wet skid resistance and low rolling resistance. Among many rubber materials, solution-polymerized styrene-butadiene rubber (SBR) has advantages such as good wear resistance, low fatigue strain heat generation, low extrusion expansion and ash content, and fast vulcanization speed. Furthermore, it also possesses advantages such as good wet skid resistance, excellent wear resistance, and low rolling resistance, making it widely used in the development of high-performance tires.

[0003] Solution-polymerized styrene-butadiene rubber (SBR) is a butadiene-styrene copolymer produced by solution polymerization of styrene and butadiene monomers. During the synthesis of SBR, the large styrene blocks severely impair the rubber's strength, elasticity, and abrasion resistance, leading to increased heat generation and rolling resistance. Therefore, researchers often use atacticing agents to reduce the content of large styrene blocks. In patent CN102344530A, the inventors used tetrahydrofuran and potassium alkoxy as atacticing agents to ensure the random distribution of styrene during the polymerization process.

[0004] On the other hand, as a non-polar rubber, solution-polymerized styrene-butadiene rubber (SBR) has poor interaction with fillers such as silica, resulting in poor powder absorption and further affecting various properties of the rubber. Currently, many researchers are focusing on the modification of SBR to enhance its interaction with fillers. Conventional in-chain modification methods for SBR mainly involve copolymerizing functionalized monomers with styrene and butadiene to introduce heteroatoms such as O, S, N, Si, and Sn into the rubber chain, thereby enhancing the polarity of the raw rubber. For example, in patent CN104017133A, the inventors copolymerized 1,1-bis(4-dimethylaminophenyl)ethylene as a functionalized monomer with styrene and butadiene via anionic polymerization to prepare nitrogen-containing in-chain functionalized SBR. This improved the dispersion of carbon black in the rubber matrix, enhancing its reinforcing effect, and effectively controlled the frictional heat generated by the movement of active polymer chains. In patent CN107082920A, the inventors modified solution-polymerized styrene-butadiene rubber (SBR) with a pyrolytically degradable monomer with a weak carbon-carbon bond structure. The weak side chains of the carbon-carbon weak-bond functionalized SBR can break upon heating, generating polymer radicals that can form strong interfacial interactions with carbon black through covalent bonds. This improves the dispersion of carbon black in the rubber matrix and enhances its reinforcing effect on the rubber matrix.

[0005] However, when functionalized monomers are copolymerized with styrene and butadiene, the functionalized monomers can affect the copolymerization effect of styrene and butadiene, influencing their randomization and consequently affecting the rolling resistance and wet skid resistance of the rubber. Simultaneously, the use of some randomizing agents can also affect subsequent rubber modifications, such as reducing coupling efficiency and end-capping efficiency. Summary of the Invention

[0006] This invention provides a method for in-chain modification of solution-polymerized styrene-butadiene rubber (SBR), which improves the interaction between SBR and silica without affecting the randomization of SBR. The in-chain modification method provided by this invention ensures the randomization of butadiene and styrene during polymerization, and allows the attributing agent to be reused after the reaction. Siloxane links are branched to the main chain through addition reactions, enhancing the nonpolarity of the raw rubber chain segments and improving the dispersibility of fillers in the rubber matrix without affecting the polymerization reaction.

[0007] The technical solution of the present invention is as follows:

[0008] A method for in-chain modification of solution-polymerized styrene-butadiene rubber, comprising the following steps:

[0009] S1. Mix styrene monomer and butadiene, solvent toluene, polar modifier single-ended hydrogen-containing silicone oil, add alkyl lithium initiator, and react;

[0010] S2. Add a platinum catalyst to the product obtained in S1 and react.

[0011] S3. Use methanol as a precipitant to precipitate the product of S2, then filter and dry.

[0012] As a preferred embodiment, in S1 of the present invention, the mixing temperature is 30-60°C.

[0013] As a preferred embodiment, in S1 of the present invention, the maximum reaction temperature is controlled to be <100°C.

[0014] As a preferred embodiment, in step S1, the reaction is kept at a constant temperature for 30-60 minutes after completion.

[0015] As a preferred embodiment, the reaction time in S2 is 1-2 hours.

[0016] As a preferred embodiment, in S1 of the present invention, the butadiene used has a purity of >99.99% and a water content of <5ppm.

[0017] As a preferred embodiment, in S1 of the present invention, the styrene used has a purity of >99.95% and a water content of <5ppm.

[0018] As a preferred embodiment, the solid content of the mixture obtained after mixing in S1 is 10-40%, preferably 20-30%.

[0019] As a preferred embodiment, in S1, the styrene content is 10-40%, preferably 20-30%, calculated based on the mass of styrene and butadiene.

[0020] As a preferred embodiment, in S1 of the present invention, the amount of single-ended hydrogen-containing silicone oil added is 0.1-0.7% of the total mass of the monomers, preferably 0.2-0.5%.

[0021] As a preferred embodiment, in S1 of the present invention, the degree of polymerization of the single-end hydrogen-containing silicone oil is ≤8, preferably ≤6.

[0022] As a preferred embodiment, the reaction temperature in S2 of the present invention is 30-80°C, preferably 40-60°C.

[0023] As a preferred embodiment, in S1 of the present invention, the alkyl lithium initiator includes one or more of n-butyllithium, sec-butyllithium, and tert-butyllithium, preferably n-butyllithium.

[0024] As a preferred embodiment, in S1 of the present invention, the platinum catalyst includes one or more of the following: a Speier catalyst, a Karstedt catalyst, and a supported platinum complex catalyst.

[0025] The modified solution-polymerized styrene-butadiene rubber described in this invention is mainly used in the tire industry.

[0026] The modified solution-polymerized styrene-butadiene rubber showed significantly improved compatibility with the filler silica during the mixing process, enhancing the mechanical properties of the rubber when used as a tire, reducing rolling resistance, and improving wet skid resistance. Detailed Implementation

[0027] The present invention can be further illustrated by the following embodiments, but the embodiments are not intended to limit the scope of protection of the present invention.

[0028] In the embodiments, the mechanical properties were tested as follows: tensile strength was tested according to GB / T528-2009, and tear strength was tested according to GB / T529-2008.

[0029] Dynamic mechanical property testing: Dynamic mechanical property testing was conducted using a DMAQ800 / RSA3 dynamic thermomechanical analyzer (USA).

[0030] Example 1

[0031] 288g of toluene was added to a 1L stainless steel reactor, followed by 18g of styrene, 54g of butadiene, and 0.2g of single-ended hydrogen-containing silicone oil (Runhe, RH-H222-4, degree of polymerization 4). The temperature was raised to 40℃. 0.5mL of 1.6M n-butyllithium was added to initiate the reaction, and the mixture was kept at 80℃ for 30min. 1.5ppm of Castrol catalyst (2% platinum content) was added, and the mixture was kept at 80℃ for 60min. The mother liquor was poured into 400g of methanol, then filtered and dried to obtain modified styrene-butadiene rubber A1.

[0032] 100 parts by weight of A1 and 40 parts by weight of silica (Qingdao Degussa) were mixed evenly in a mixer. Then, 1 part by weight of antioxidant 4020 (N-(1,3-dimethylbutyl)-N'-phenylhydroquinone), 1 part by weight of sulfur accelerator (tetramethylthiuram disulfide), and 1.7 parts by weight of sulfur were added. Finally, the mixture was vulcanized for 20 minutes to obtain vulcanized rubber A2.

[0033] Example 2

[0034] 288g of toluene was added to a 1L stainless steel reactor, followed by 18g of styrene, 54g of butadiene, and 0.3g of single-ended hydrogen-containing silicone oil (Runhe, RH-H222-3, degree of polymerization 3). The temperature was raised to 40℃. 0.5mL of 1.6M n-butyllithium was added to initiate the reaction, and the mixture was kept at 80℃ for 30min. 1.5ppm of Castrol catalyst (2% platinum content) was added, and the mixture was kept at 80℃ for 60min. The mother liquor was poured into 400g of methanol, then filtered and dried to obtain modified styrene-butadiene rubber B1.

[0035] 100 parts by weight of B1 and 40 parts by weight of silica (Qingdao Degussa) were mixed evenly in a mixer. Then, 1 part by weight of antioxidant 4020 (N-(1,3-dimethylbutyl)-N'-phenylhydroquinone), 1 part by weight of sulfur accelerator (tetramethylthiuram disulfide), and 1.7 parts by weight of sulfur were added. Finally, the mixture was vulcanized for 20 minutes to obtain vulcanized rubber B2.

[0036] Example 3

[0037] 288g of toluene was added to a 1L stainless steel reactor, followed by 18g of styrene, 54g of butadiene, and 0.3g of single-ended hydrogen-containing silicone oil (Runhe, RH-H222-4, degree of polymerization 4). The temperature was raised to 40℃. 0.5mL of 1.6M n-butyllithium was added to initiate the reaction, and the mixture was kept at 80℃ for 30min. 1.5ppm of Castrol catalyst (2% platinum content) was added, and the mixture was kept at 80℃ for 60min. The mother liquor was poured into 400g of methanol, then filtered and dried to obtain modified styrene-butadiene rubber C1.

[0038] 100 parts by weight of C1 and 40 parts by weight of silica (Qingdao Degussa) were mixed evenly in a mixer. Then, 1 part by weight of antioxidant 4020 (N-(1,3-dimethylbutyl)-N'-phenylhydroquinone), 1 part by weight of sulfur accelerator (tetramethylthiuram disulfide), and 1.7 parts by weight of sulfur were added. Finally, the mixture was vulcanized for 20 minutes to obtain vulcanized rubber C2.

[0039] Comparative Example 1

[0040] 288g of toluene was added to a 1L stainless steel reactor, followed by 18g of styrene and 54g of butadiene. The mixture was heated to 40°C. 0.5mL of 1.6M n-butyllithium was added to initiate the reaction, and the mixture was kept at 80°C for 30 minutes. The resulting mother liquor was poured into 400g of methanol, then filtered and dried to obtain modified styrene-butadiene rubber D1.

[0041] 100 parts by weight of D1 and 40 parts by weight of silica (Qingdao Degussa) were mixed evenly in a mixer. Then, 1 part by weight of antioxidant 4020 (N-(1,3-dimethylbutyl)-N'-phenylhydroquinone), 1 part by weight of sulfur accelerator (tetramethylthiuram disulfide), and 1.7 parts by weight of sulfur were added. Finally, the mixture was vulcanized for 20 minutes to obtain vulcanized rubber D2.

[0042] Comparative Example 2

[0043] 288g of toluene was added to a 1L stainless steel reactor, followed by 18g of styrene, 54g of butadiene, and 2g of single-ended hydrogen-containing silicone oil (Runhe, RH-H222-4, degree of polymerization 4). The temperature was raised to 40℃. 0.5mL of 1.6M n-butyllithium was added to initiate the reaction, and the mixture was kept at 80℃ for 30min. 1.5ppm of Castrol catalyst (2% platinum content) was added, and the mixture was kept at 80℃ for 60min. The mother liquor was poured into 400g of methanol, then filtered and dried to obtain modified styrene-butadiene rubber E1.

[0044] 100 parts by weight of E1 and 40 parts by weight of silica (Qingdao Degussa) were mixed evenly in a mixer. Then, 1 part by weight of antioxidant 4020 (N-(1,3-dimethylbutyl)-N'-phenylhydroquinone), 1 part by weight of sulfur accelerator (tetramethylthiuram disulfide), and 1.7 parts by weight of sulfur were added. Finally, the mixture was vulcanized for 20 minutes to obtain vulcanized rubber E2.

[0045] Comparative Example 3

[0046] 288g of toluene was added to a 1L stainless steel reactor, followed by 18g of styrene, 54g of butadiene, and 0.3g of single-ended hydrogen-containing silicone oil (Runhe, RH-H222-10, degree of polymerization 10). The temperature was raised to 40℃. 0.5mL of 1.6M n-butyllithium was added to initiate the reaction, and the mixture was kept at 80℃ for 30min. 1.5ppm of Castrol catalyst (2% platinum content) was added, and the mixture was kept at 80℃ for 60min. The mother liquor was poured into 400g of methanol, then filtered and dried to obtain modified styrene-butadiene rubber F1.

[0047] 100 parts by weight of F1 and 40 parts by weight of silica (Qingdao Degussa) were mixed evenly in a mixer. Then, 1 part by weight of antioxidant 4020 (N-(1,3-dimethylbutyl)-N'-phenylhydroquinone), 1 part by weight of sulfur accelerator (tetramethylthiuram disulfide), and 1.7 parts by weight of sulfur were added. Finally, the mixture was vulcanized for 20 minutes to obtain vulcanized rubber F2.

[0048] The test results for all embodiments and comparative examples are shown in Table 1.

[0049] Table 1 Test Results

[0050]

[0051]

[0052] The data shows that the chain-modified solution-polymerized styrene-butadiene rubber prepared according to the steps described in this invention not only has high tensile strength and tear strength, but also excellent anti-slip properties and low rolling resistance.

[0053] The above description is merely a specific embodiment of the present invention and does not limit the scope of the patent. Any equivalent process or reagent substitution made using the content described in the present invention specification, or any direct or indirect application in other related technical fields, are similarly included within the scope of protection of the present invention patent.

Claims

1. A method for in-chain modification of solution-polymerized styrene-butadiene rubber, comprising the following steps: S1. Mix styrene monomer and butadiene, solvent toluene, polar modifier single-ended hydrogen-containing silicone oil, add alkyl lithium initiator, and react; S2. Add a platinum catalyst to the product obtained in S1 and react. S3. Use methanol as a precipitant to precipitate the product of S2, then filter and dry.

2. The method according to claim 1, characterized in that, In step S1, the mixing temperature is 30-60℃; the maximum reaction temperature is controlled to be <100℃; and the temperature is maintained for 30-60 minutes after the reaction is completed.

3. The method according to claim 1 or 2, characterized in that, The solid content of the mixture obtained after mixing in S1 is 10-40%, preferably 20-30%.

4. The method according to any one of claims 1-3, characterized in that, In S1, the styrene content is 10-40%, preferably 20-30%, calculated based on the mass of styrene and butadiene.

5. The method according to any one of claims 1-4, characterized in that, In step S1, the amount of single-ended hydrogen-containing silicone oil added is 0.1-0.7% of the total mass of the monomers, preferably 0.2-0.5%.

6. The method according to any one of claims 1-5, characterized in that, In S1, the degree of polymerization of the single-end hydrogen-containing silicone oil is ≤8, preferably ≤6.

7. The method according to any one of claims 1-6, characterized in that, The reaction temperature in S2 is 30-80℃, preferably 40-60℃.

8. The method according to any one of claims 1-7, characterized in that, In S1, the alkyl lithium initiator includes one or more of n-butyllithium, sec-butyllithium, and tert-butyllithium, preferably n-butyllithium.

9. The method according to any one of claims 1-8, characterized in that, In S1, the platinum catalyst includes one or more of the following: Speier catalyst, Karstedt catalyst, and supported platinum complex catalyst.

10. The application of the modified solution-polymerized styrene-butadiene rubber prepared by the method according to any one of claims 1-9 in the tire industry.

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