A white carbon black dispersant for rubber, and a preparation method and application thereof

Abstract

This invention discloses a precipitated silica dispersant for rubber, its preparation method, and its application, relating to the field of rubber additives. The precipitated silica dispersant for rubber is made from raw materials comprising the following proportions: modified vegetable oil and hydroxide, wherein the molar ratio of the modified vegetable oil to the hydroxide is 1:(0.3-0.6), and the modified vegetable oil is copolymerized from vegetable oil monomers, benzene ring unsaturated monomers, and cashew nut phenol. This application provides an environmentally friendly and safe precipitated silica dispersant that can significantly improve the dispersibility of precipitated silica in rubber compounds while simultaneously improving the mechanical properties of the rubber compounds.

Description

Technical Field

[0001] This invention relates to the field of rubber additives, and in particular to a precipitated silica dispersant for rubber, its preparation method, and its application. Background Technology

[0002] Silica is widely used in the rubber industry as a reinforcing filler, especially in tire tread rubber. The large number of silanol groups on the surface of silica makes it easier for tires to interact with water molecules when driving on wet and slippery roads, thereby improving wet skid resistance. On the other hand, it also improves rolling resistance, wear resistance and other properties.

[0003] However, as highly polar nanoparticles, silica tends to agglomerate. The polysiloxanes within silica and the active silanol groups on its surface, along with their adsorbed water, make silica hydrophilic, hindering its wetting and dispersion in the rubber organic phase. When a large amount of silica is added, uneven dispersion leads to a significant increase in rubber viscosity, negatively impacting its processing properties. Therefore, it is necessary to add silica dispersants to improve its dispersion in rubber compounds.

[0004] There are currently three main types of silica dispersants: silane coupling agents, alcohols and alkanolamines, and zinc salts. However, the active groups in silica can weaken the effect of silane coupling agents and affect the performance of rubber compounds. Alcohols and alkanolamines are small molecule compounds with poor compatibility with rubber, and their improvement on silica dispersibility is limited. Zinc salts pose a risk of heavy metal emissions, have poor environmental performance, and have limited dispersion stability, which may interfere with the vulcanization system.

[0005] Based on the above factors, there is a need to develop an environmentally friendly and safe silica dispersant that can greatly improve the dispersibility of silica in rubber compounds, while also improving the mechanical properties of the rubber compounds. Summary of the Invention

[0006] To address the aforementioned issues, this application provides a precipitated silica dispersant for rubber, its preparation method, and its application.

[0007] This application provides a precipitate dispersant for rubber, its preparation method, and its application, employing the following technical solution: In a first aspect, this application provides a precipitated silica dispersant for rubber, made from raw materials comprising the following proportions: modified vegetable oil and hydroxide, wherein the molar ratio of the modified vegetable oil to the hydroxide is 1:(0.3-0.6), and the modified vegetable oil is copolymerized from vegetable oil monomers, benzene ring unsaturated monomers and cashew phenol.

[0008] By employing the above technical solution, partially saponified products of modified vegetable oil and hydroxides are selected. These products contain a mixture of fatty acid soaps, vegetable oil mono / diglycerides, and glycerol. The fatty acid soaps are anionic surfactants containing lipophilic long-chain fatty acid alkyl groups and hydrophilic carboxylic acid groups, which can adsorb onto the surface of silica and be compatible with the rubber matrix, reducing silica agglomeration. The vegetable oil mono / diglycerides can effectively entangle with rubber molecular chains, providing internal lubrication and exhibiting better compatibility with non-polar rubbers, reducing interfacial defects within the rubber compound. Glycerol can penetrate into the silica agglomerates, further enhancing dispersion. Therefore, the partially saponified products can promote silica dispersion and exhibit good compatibility with rubber, reducing the Mooney viscosity of the rubber compound and improving the tensile strength, abrasion resistance, and tear resistance of the vulcanized rubber.

[0009] The modified vegetable oil is a copolymer of vegetable oil monomers, benzene ring unsaturated monomers, and cashew phenol. Introducing benzene rings into the molecular chain of the modified vegetable oil can enhance its compatibility with non-polar rubber and improve the rigidity, heat resistance, and weather resistance of rubber products. The introduction of phenolic hydroxyl groups provides polar sites, which can further form strong hydrogen bonds with the hydroxyl groups on the surface of silica, thereby enhancing the dispersing effect.

[0010] Optionally, in the modified vegetable oil, the molar ratio of vegetable oil monomer, benzene ring unsaturated monomer and cashew phenol is 1:(0.8-1.2):(0.6-1).

[0011] By adopting the above technical solutions, the excessive cross-linking of double bonds in vegetable oils can be avoided by controlling the monomer ratio, thus controlling the degree of cross-linking and molecular weight of modified vegetable oils and avoiding subsequent saponification difficulties. At the same time, excessive cashew phenol can be avoided to prevent the oxidation of phenolic hydroxyl groups, which would cause the copolymer to turn yellow, and cashew phenol residue can be avoided to delay rubber vulcanization.

[0012] Optionally, the vegetable oil monomer may be selected from one of soybean oil, castor oil, sunflower seed oil, flaxseed oil, corn oil, or peanut oil.

[0013] By adopting the above technical solution, vegetable oils with unsaturated double bonds are selected, with triglycerides as the main component. These oils can be saponified and copolymerized, and the cost is relatively low.

[0014] Optionally, the benzene ring unsaturated monomer is selected from one of 2,6-di-tert-butyl-4-vinylphenol, p-tert-butylvinylbenzene, and p-tert-butyl-α-methylstyrene.

[0015] By adopting the above technical solution, monomers with benzene rings and unsaturated double bonds are selected. These monomers are not easy to self-polymerize and can copolymerize with vegetable oils at low temperatures. Benzene rings and tert-butyl groups can be introduced into modified vegetable oils, increasing rigidity. When added to rubber as a silica dispersant, the heat resistance and aging resistance of the rubber are improved.

[0016] Optionally, the cashew phenol is selected from maleic anhydride-grafted cashew phenol and is prepared through the following steps: Add cashew phenol to the reactor, purge the air in the reactor with nitrogen, heat to 110-120℃, weigh maleic anhydride and add it to the reactor in 3 portions, 15-20 min apart each time, add p-toluenesulfonic acid, heat to 160-180℃, keep the reaction under nitrogen for 2-3 h, cool to 80-100℃, filter to obtain maleic anhydride grafted cashew phenol.

[0017] By adopting the above technical solution, the phenolic hydroxyl groups of cashew phenol undergo ring-opening esterification with maleic anhydride, thereby introducing carboxyl groups into the maleic anhydride-grafted cashew phenol. This forms a dual effect of hydrogen bonds and ionic bonds with silica, enhancing the affinity for silica. At the same time, the carboxyl groups participate in the subsequent saponification reaction, further improving the dispersion efficiency. The double bonds in maleic anhydride can also enter the copolymerization system, further improving rigidity and crosslinking degree.

[0018] Optionally, the p-toluenesulfonic acid accounts for 2%-4% of the mass of cashew phenol, and the molar ratio of maleic anhydride to cashew phenol is (0.8-1):1.

[0019] Optionally, the hydroxide may be selected from sodium hydroxide or potassium hydroxide.

[0020] Secondly, this application provides a method for preparing a silica dispersant for rubber, comprising the following steps: The modified vegetable oil was heated to 65-70℃ under a nitrogen atmosphere and stirred until the oil became transparent and uniform. The hydroxide was mixed with deionized water and glycerin to obtain a hydroxide solution. The hydroxide solution was slowly added to the modified vegetable oil in three portions, and the temperature was raised to 90-95℃. The reaction was maintained at this temperature for 2.5-3 hours. Stop the reaction and cool to 60℃. Add citric acid to adjust the pH of the reaction system to 7-8. Dehydrate the reaction product at 100-110℃ and -0.085--0.09MPa for 1.5-2h until the product moisture content is ≤0.5%. Cool the dehydrated product to 80℃ for later use. The product is pumped to the hopper of the steel belt granulator at a discharge speed of 5-8 kg / h and a running speed of 0.3-0.5 m / s. Cooling water flows under the steel belt, and the product is cooled and solidified to form granules. After sieving, the product is obtained as a silica dispersant.

[0021] By adopting the above technical solution, a composite product is obtained by using modified vegetable oil and hydroxide for controlled partial saponification, followed by dehydration and granulation. Furthermore, by adding citric acid to control the residual free alkali, the resulting product can be added to the rubber system as a silica dispersant. This is environmentally friendly and safe, and can greatly improve the dispersibility of silica and the mechanical properties of rubber products.

[0022] Optionally, the modified vegetable oil is prepared by the following steps: Mix vegetable oil monomers, benzene ring unsaturated monomers, cashew phenol and anhydrous n-hexane, purge the air with nitrogen, heat to 40-45℃ and stir for 30-40 minutes to form an oil phase solution. The oil phase solution was cooled to 5-10℃, a solid acid catalyst was added, and the reaction was stopped after 6-6.5 h at low temperature. The solid acid catalyst was separated by vacuum filtration, and the filtrate was distilled under reduced pressure to remove the hexane solvent. The product was dried at 60-65℃ for 1-2 h to obtain the modified vegetable oil.

[0023] By adopting the above technical solution and selecting a solid acid catalyst, the controllable copolymerization of ternary monomers is achieved under low temperature conditions. The product retains the triglyceride skeleton of vegetable oil and introduces phenolic hydroxyl groups and benzene rings, with no catalyst residue, which is suitable for the preparation of silica dispersants.

[0024] Thirdly, this application provides the application of a silica dispersant for rubber in silica-filled rubber products.

[0025] In summary, this application has at least one of the following beneficial effects: 1. Partial saponification products of modified vegetable oil and hydroxides are selected. These products contain a mixture of fatty acid soaps, mono / diglycerides of vegetable oil, and glycerol. The fatty acid soaps are anionic surfactants containing lipophilic long-chain fatty acid alkyl groups and hydrophilic carboxylic acid groups, which can adsorb onto the surface of silica and are compatible with the rubber matrix, reducing silica agglomeration. The mono / diglycerides of vegetable oil can effectively entangle with rubber molecular chains, acting as internal lubricants and exhibiting better compatibility with non-polar rubbers, reducing interfacial defects within the rubber compound. Glycerol can penetrate into the silica agglomerates, further enhancing dispersion. Therefore, the partially saponified products can promote silica dispersion and have good compatibility with rubber, reducing the Mooney viscosity of the rubber compound and improving the tensile strength, abrasion resistance, and tear resistance of the vulcanized rubber.

[0026] The modified vegetable oil is a copolymer of vegetable oil monomers, benzene ring unsaturated monomers, and cashew phenol. Introducing benzene rings into the molecular chain of the modified vegetable oil can enhance its compatibility with non-polar rubber and improve the rigidity, heat resistance, and weather resistance of rubber products. The introduction of phenolic hydroxyl groups provides polar sites, which can further form strong hydrogen bonds with the hydroxyl groups on the surface of silica, thereby enhancing the dispersing effect.

[0027] 2. The phenolic hydroxyl groups of cashew phenol undergo ring-opening esterification with maleic anhydride, thereby introducing carboxyl groups into the maleic anhydride-grafted cashew phenol. This forms a dual effect of hydrogen bonds and ionic bonds with silica, enhancing the affinity for silica. At the same time, the carboxyl groups participate in the subsequent saponification reaction, further improving the dispersion efficiency. The double bonds in maleic anhydride can also enter the copolymerization system, further improving rigidity and crosslinking degree. Detailed Implementation

[0028] The following provides a more detailed explanation of this application in conjunction with application examples 1-6 and comparative application examples 1-3.

[0029] Raw material source: The solid acid catalyst used was Maghnite-Na solid acid, purchased from Wuhan Kemic Biopharmaceutical Co., Ltd. Example

[0030] Example 1 A dispersant for rubber-grade silica is made from a raw material comprising a modified vegetable oil and a hydroxide in a molar ratio of 1:0.3, wherein the hydroxide is sodium hydroxide.

[0031] The modified vegetable oil is copolymerized from vegetable oil monomers, benzene ring unsaturated monomers and cashew phenol in a molar ratio of 1:0.8:0.6. The vegetable oil monomer is soybean oil, and the benzene ring unsaturated monomer is 2,6-di-tert-butyl-4-vinylphenol.

[0032] A method for preparing a silica dispersant for rubber includes the following steps: Vegetable oil monomers, benzene ring unsaturated monomers, cashew phenols and anhydrous n-hexane were mixed, with the mass of anhydrous n-hexane being 2.5 times the mass of vegetable oil monomers. Nitrogen gas was introduced to replace the air, and the mixture was heated to 40°C and stirred for 30 minutes to form an oil phase solution. The oil phase solution was cooled to 5°C, a solid acid catalyst was added, and the reaction was stopped after 6 hours at low temperature. The solid acid catalyst was separated by vacuum filtration, and the filtrate was distilled under reduced pressure to remove the hexane solvent. The product was dried at 60°C for 2 hours to obtain the modified vegetable oil.

[0033] The modified vegetable oil was heated to 65°C under a nitrogen atmosphere and stirred until the oil became transparent and uniform. The hydroxide, deionized water and glycerol were mixed to obtain a hydroxide solution. The mass of deionized water was twice that of the hydroxide and the mass of glycerol was 2.5 times that of the hydroxide. The hydroxide solution was slowly added to the modified vegetable oil in three portions. The temperature was raised to 90°C and the reaction was maintained for 2.5 hours. Stop the reaction and cool to 60°C. Add citric acid to adjust the pH of the reaction system to 7-8. Dehydrate the reaction product at 100°C and -0.085MPa for 1.5 hours until the product moisture content is ≤0.5%. Cool the dehydrated product to 80°C for later use. The product is pumped to the hopper of the steel belt granulator at a discharge speed of 5 kg / h and a running speed of 0.3 m / s. Cooling water flows under the steel belt, and the product is cooled and solidified to form granules. After sieving, a silica dispersant with a particle size of 2 mm is obtained.

[0034] Example 2 A dispersant for rubber-grade silica is made from a raw material comprising a modified vegetable oil and a hydroxide in a molar ratio of 1:0.6, wherein the hydroxide is sodium hydroxide.

[0035] The modified vegetable oil is copolymerized from vegetable oil monomers, benzene ring unsaturated monomers and cashew phenol in a molar ratio of 1:1.2:1. Soybean oil is selected as the vegetable oil monomer and 2,6-di-tert-butyl-4-vinylphenol is selected as the benzene ring unsaturated monomer.

[0036] A method for preparing a silica dispersant for rubber includes the following steps: Vegetable oil monomers, benzene ring unsaturated monomers, cashew phenols and anhydrous n-hexane were mixed, with the mass of anhydrous n-hexane being twice the mass of vegetable oil monomers. Nitrogen gas was introduced to replace the air, and the mixture was heated to 45°C and stirred for 40 minutes to form an oil phase solution. The oil phase solution was cooled to 10°C, a solid acid catalyst was added, and the reaction was stopped after 6.5 h at low temperature. The solid acid catalyst was separated by vacuum filtration, and the filtrate was distilled under reduced pressure to remove the hexane solvent. The product was dried at 65°C for 1 h to obtain the modified vegetable oil.

[0037] The modified vegetable oil was heated to 70°C under a nitrogen atmosphere and stirred until the oil became transparent and uniform. The hydroxide, deionized water and glycerol were mixed to obtain a hydroxide solution. The mass of deionized water was 3 times that of hydroxide and the mass of glycerol was 2.5 times that of hydroxide. The hydroxide solution was slowly added to the modified vegetable oil in 3 portions. The temperature was raised to 95°C and the reaction was maintained for 3 hours. Stop the reaction and cool to 60°C. Add citric acid to adjust the pH of the reaction system to 7-8. Dehydrate the reaction product at 110°C and -0.09MPa for 2 hours until the product moisture content is ≤0.5%. Cool the dehydrated product to 80°C for later use. The product is pumped to the hopper of the steel belt granulator at a discharge speed of 8 kg / h and a running speed of 0.5 m / s. Cooling water flows under the steel belt, and the product is cooled and solidified to form granules. After sieving, a silica dispersant with a particle size of 3 mm is obtained.

[0038] Example 3 A precipitated silica dispersant for rubber, the difference between this embodiment and Example 1 is that it is made from a raw material containing modified vegetable oil and hydroxide in a molar ratio of 1:0.3, wherein potassium hydroxide is selected as the hydroxide.

[0039] The modified vegetable oil is copolymerized from vegetable oil monomers, benzene ring unsaturated monomers and cashew phenol in a molar ratio of 1:0.8:0.6. The vegetable oil monomer is castor oil and the benzene ring unsaturated monomer is p-tert-butylvinylbenzene.

[0040] Example 4 A precipitated silica dispersant for rubber, the difference between this embodiment and Example 1 is that it is made from raw materials containing modified vegetable oil and hydroxide in a molar ratio of 1:0.4, wherein potassium hydroxide is selected as the hydroxide.

[0041] The modified vegetable oil is copolymerized from vegetable oil monomers, benzene ring unsaturated monomers and cashew phenol in a molar ratio of 1:1:0.8. Sunflower seed oil is selected as the vegetable oil monomer, and p-tert-butyl-α-methylstyrene is selected as the benzene ring unsaturated monomer.

[0042] Example 5 A dispersant for precipitated silica used in rubber, the difference between this embodiment and Example 1 is that the cashew phenol in the modified vegetable oil is maleic anhydride-grafted cashew phenol, prepared through the following steps: Cashew phenol was added to the reactor, nitrogen gas was introduced to replace the air in the reactor, and the temperature was raised to 110°C. Maleic anhydride was weighed and added to the reactor in three portions with a molar ratio of maleic anhydride to cashew phenol of 0.8:1, with an interval of 15 minutes between each addition. 2% p-toluenesulfonic acid (based on the mass of cashew phenol) was added, and the temperature was raised to 160°C. The reaction was maintained under nitrogen for 2 hours, cooled to 80°C, and filtered to obtain maleic anhydride-grafted cashew phenol.

[0043] Example 6 A dispersant for precipitated silica used in rubber, the difference between this embodiment and Example 1 is that the cashew phenol in the modified vegetable oil is maleic anhydride-grafted cashew phenol, prepared through the following steps: Cashew phenol was added to the reactor, nitrogen gas was introduced to replace the air in the reactor, and the temperature was raised to 120°C. Maleic anhydride was weighed and added to the reactor in three portions with a molar ratio of maleic anhydride to cashew phenol of 1:1, with an interval of 20 min between each addition. 4% p-toluenesulfonic acid (by mass of cashew phenol) was added, and the temperature was raised to 180°C. The reaction was maintained under nitrogen for 3 hours, cooled to 100°C, and filtered to obtain maleic anhydride-grafted cashew phenol. Comparative Example

[0044] Comparative Example 1 A silica dispersant for rubber is described. The difference between this comparative example and Example 1 is that the silica dispersant used is an existing silica dispersant, specifically EFN-S20, which was purchased from Shandong Hasar Chemical Technology Co., Ltd.

[0045] Comparative Example 2 A dispersant for precipitated silica used in rubber, the difference between this comparative example and Example 2 is that the modified vegetable oil is copolymerized from vegetable oil monomers and benzene ring unsaturated monomers in a molar ratio of 1:0.8, wherein the vegetable oil monomer is selected from soybean oil and the benzene ring unsaturated monomer is selected from 2,6-di-tert-butyl-4-vinylphenol.

[0046] Comparative Example 3 A dispersant for precipitated silica used in rubber, the difference between this comparative example and Example 1 is that the modified vegetable oil is copolymerized from vegetable oil monomers and cashew phenol in a molar ratio of 1:0.6, wherein the vegetable oil monomer is selected from soybean oil. Application examples

[0047] The application of a precipitated silica dispersant for rubber in precipitated silica-filled rubber products, wherein the rubber products are tire tread rubber.

[0048] The tread compound is made from the following raw materials in parts by weight: 100 parts of styrene-butadiene rubber, SBR1502, a product of PetroChina Jilin Chemical Company; 50 parts of silica, silica N175, product of Qingdao Rhodia Company; 3 parts of silica dispersant; 5 parts zinc oxide; 1.5 parts stearic acid; 4 parts of silane coupling agent Si-69; Accelerator D, 1.7 parts, Qingdao Rhein Chemical Co., Ltd.; Accelerator DM 0.8 parts, Qingdao Rhein Chemical Co., Ltd.; 2.5 parts sulfur.

[0049] The silica dispersant can be prepared from Examples 1-6, thereby preparing the tread rubber of Application Examples 1-6 respectively.

[0050] The preparation process of the tread compound is as follows: The masterbatch is mixed in an XM370 internal mixer with an automatic mixing process. The internal mixer rotor speed is 55 rpm, the top jack pressure is 0.5 MPa, and the initial temperature is 70℃. First, styrene-butadiene rubber is added and plasticized for 2 minutes. Then, zinc oxide, stearic acid, accelerator D, accelerator DM, and silica dispersant are added and mixed for 3 minutes. Silica and silane coupling agent Si-69 are added and mixed for 3 minutes. Then, the top jack is raised, and the mixture is cleaned for 3 minutes before being discharged. The discharge temperature is controlled at <130℃. The final rubber compounding was carried out in an F270 internal mixer. Sulfur was added to the masterbatch, and the discharge temperature was controlled at 100±5℃.

[0051] Comparative application examples The tread compound was prepared using the raw material ratio and preparation method in the application examples. The difference was that the silica dispersant in the tread compound was prepared by comparative examples 1-3, thus producing comparative application examples 1-3 respectively. Performance testing

[0052] Filler dispersibility test: The rubber compounds obtained from test cases 1-5 and comparative application cases 1-3 were tested using an RPA rheometer. The temperature was set at 60℃, the strain scan range was 0.3%-100%, and the frequency was 1Hz. The difference between the low strain modulus and the high strain modulus in the test results reflects the dispersibility of the filler. The test results are shown in Table 1.

[0053] Mooney viscosity of the rubber compound: The Mooney viscosity was tested according to the method of GB / T 1232.1-2000 "Determination of unvulcanized rubber by disc shear viscometer - Part 1: Determination of Mooney viscosity" under the conditions of ML(1+4) 100℃. The test results are shown in Table 1.

[0054] Mechanical property testing of tread rubber: The tensile strength and tear strength of the vulcanized tread rubber were tested. The tensile properties were tested according to GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", and the tear properties of the vulcanized rubber were tested according to GB / T 529-2008 "Determination of tear strength of vulcanized rubber or thermoplastic rubber (trouser-shaped, right-angled and crescent-shaped specimens)". The speed was set to 500 mm / min for both tests. The test results are shown in Table 1.

[0055] Table 1 Low strain (0.3%) modulus / KPa High strain (100%) modulus / KPa Mooney viscosity Tensile strength / MPa Tear strength / N / mm Application Example 1 548.8 136.5 53.6 23.5 58 Application Example 2 540.6 132.2 52.8 24.3 55 Application Example 3 544.1 134.7 53.1 24.1 55 Application Example 4 543.3 134.3 53.4 23.7 56 Application Example 5 529.4 129.4 52.1 25.8 62 Application Example 6 532.2 131.5 52.3 25.6 61 Comparative Example 1 675.1 138.7 58.9 17.8 48 Comparative Example 2 634.7 140.5 56.6 21.7 53 Comparative Example 3 659.2 143.8 55.8 21.3 51 As shown in Table 1, at low strain, the network structure formed by the filler in the rubber is relatively intact. However, as the strain increases, the weak physical bonds between the fillers are broken. This breakdown of the filler network releases the fixed rubber molecules, thus reducing the dynamic modulus. Therefore, the Payne effect is used to measure the filler network. The stronger the Payne effect, i.e., the greater the difference between the high and low strain moduli, the weaker the interaction between the fillers and the lower the dispersibility of the silica.

[0056] As shown in Table 1, and in conjunction with Application Examples 1-4, the silica dispersant prepared in this application, compared to commercially available silica dispersants, uses a composite product of modified vegetable oil and partially saponified hydroxide. After removing fatty acid soaps, it retains mono / diglycerides of vegetable oil, which can further improve the compatibility with rubber, thereby making the silica dispersibility stronger. As a result, the difference between the high strain modulus and the low strain modulus of the tread compound in Application Examples 1-4 is smaller.

[0057] Furthermore, after the silica dispersant in Examples 1-4 was added to the rubber compound, the Mooney viscosity of the compound decreased, the injection molding performance was improved, and the content of the binder increased significantly by increasing the contact area and compatibility between silica and rubber, resulting in a substantial improvement in the overall reinforcing properties of the rubber compound. Therefore, both the tensile strength and tear strength of the rubber compound were significantly enhanced.

[0058] Compared to Application Example 1, Application Examples 5-6 used maleic anhydride-grafted cashew phenol in the synthesis of modified vegetable oil. Carboxyl groups were introduced to replace the original hydroxyl groups of cashew phenol, which improved the crosslinking degree of the saponification product and the binding effect with silica. This improved the dispersibility and reinforcing effect of silica, and further enhanced the performance of the tread compound.

[0059] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A white carbon black dispersant for rubber, characterized by, It is made from raw materials comprising the following proportions: modified vegetable oil and hydroxide, wherein the molar ratio of the modified vegetable oil to the hydroxide is 1:(0.3-0.6), and the modified vegetable oil is copolymerized from vegetable oil monomers, benzene ring unsaturated monomers and cashew phenol.

2. The silica dispersing agent for rubber according to claim 1, characterized by: In the modified vegetable oil, the molar ratio of vegetable oil monomer, benzene ring unsaturated monomer and cashew phenol is 1:(0.8-1.2):(0.6-1).

3. The silica dispersing agent for rubber according to claim 2, characterized by: The vegetable oil monomer is selected from one of soybean oil, castor oil, sunflower seed oil, flaxseed oil, corn oil, and peanut oil.

4. The silica dispersing agent for rubber according to claim 2, characterized by: The benzene ring unsaturated monomer is selected from one of 2,6-di-tert-butyl-4-vinylphenol, p-tert-butylvinylbenzene, and p-tert-butyl-α-methylstyrene.

5. The silica dispersing agent for rubber according to claim 1, characterized by: The cashew phenol is selected from maleic anhydride-grafted cashew phenol and is prepared through the following steps: Add cashew phenol to the reactor, purge the air in the reactor with nitrogen, heat to 110-120℃, weigh maleic anhydride and add it to the reactor in 3 portions, 15-20 min apart each time, add p-toluenesulfonic acid, heat to 160-180℃, keep the reaction under nitrogen for 2-3 h, cool to 80-100℃, filter to obtain maleic anhydride grafted cashew phenol.

6. The silica dispersant for rubber according to claim 5, characterized by: The p-toluenesulfonic acid accounts for 2%-4% of the mass of cashew phenol, and the molar ratio of maleic anhydride to cashew phenol is (0.8-1):

1.

7. The silica dispersing agent for rubber according to claim 1, characterized by: The hydroxide is selected from either sodium hydroxide or potassium hydroxide.

8. The method of claim 1-7, wherein the method is characterized in that, Includes the following steps: The modified vegetable oil was heated to 65-70℃ under a nitrogen atmosphere and stirred until the oil became transparent and uniform. The hydroxide was mixed with deionized water and glycerin to obtain a hydroxide solution. The hydroxide solution was slowly added to the modified vegetable oil in three portions, and the temperature was raised to 90-95℃. The reaction was maintained at this temperature for 2.5-3 hours. Stop the reaction and cool to 60℃. Add citric acid to adjust the pH of the reaction system to 7-8. Dehydrate the reaction product at 100-110℃ and -0.085--0.09MPa for 1.5-2h until the product moisture content is ≤0.5%. Cool the dehydrated product to 80℃ for later use. The product is pumped to the hopper of the steel belt granulator at a discharge speed of 5-8 kg / h and a running speed of 0.3-0.5 m / s. Cooling water flows under the steel belt, and the product is cooled and solidified to form granules. After sieving, the product is obtained as a silica dispersant.

9. The method of claim 8, wherein the white carbon black dispersant for rubber is prepared by adding the silane coupling agent to the white carbon black and then adding the dispersant to the white carbon black. The modified vegetable oil is prepared through the following steps: Mix vegetable oil monomers, benzene ring unsaturated monomers, cashew phenol and anhydrous n-hexane, purge the air with nitrogen, heat to 40-45℃ and stir for 30-40 minutes to form an oil phase solution. The oil phase solution was cooled to 5-10℃, a solid acid catalyst was added, and the reaction was stopped after 6-6.5 h at low temperature. The solid acid catalyst was separated by vacuum filtration, and the filtrate was distilled under reduced pressure to remove the hexane solvent. The product was dried at 60-65℃ for 1-2 h to obtain the modified vegetable oil.

10. The use of the silica dispersant for rubber as described in any one of claims 1-7 in silica-filled rubber products.