Low voc silane polymer for tire processing and method of synthesis thereof

Abstract

The present application relates to a kind of low VOC silane polymer for tire processing and its synthesis method.The method includes mixing long-chain polyether or polyether polyol with sulfur-containing silane phase, and by constantly introducing hydrogen sulfide gas, ester exchange reaction is carried out under corresponding catalyst, and finally corresponding silane polymer is synthesized.The silane polymer can effectively improve the dispersion effect of white carbon black during tire synthesis stage, while the production process does not produce VOC gas, can effectively improve the safety during tire processing, while compared with traditional mercapto silane coupling agent, the silane of the present application can significantly balance the wet skid resistance and rolling friction resistance of tire, improve the application performance of tire.

Description

Technical Field

[0001] This invention relates to the field of silane coupling agent technology, specifically to a low-VOC silane polymer for tire processing and its synthesis method. Background Technology

[0002] Sulfur-containing silanes are important organosilicon intermediates, mainly used in compounding with precipitated silica to produce "green tires." Compared to carbon black, precipitated silica-filled tires offer superior traction and wear life while reducing fuel consumption. Therefore, the new generation of low-rolling-resistance, low-fuel-consumption "green tires" filled with precipitated silica has become the mainstream of the tire industry in recent years. However, precipitated silica contains a large number of hydroxyl groups on its surface, resulting in high acidity, hygroscopicity, and hydrophilicity, leading to poor compatibility with rubber. This results in problems such as prolonged vulcanization time and reduced cross-linking during the compounding process. Adding silane coupling agents to modify the surface of precipitated silica can reduce its surface polarity and improve its compatibility with rubber.

[0003] The most commonly used silanes in "green tires" are bis-[3-(triethoxysilane)-propyl]-tetrasulfide (Si-69 or TESPT) and bis-[3-(triethoxysilane)-propyl]-disulfide (Si-75). However, on the one hand, because the polysulfide bonds in these silane coupling agents are capped by alkoxysilanes during tire processing, the vulcanization time is relatively long and the processing efficiency is relatively low. On the other hand, during the high-temperature rubber compounding process, the ethoxy groups can spontaneously detach, forming volatile ethanol gas. Due to its flammability and explosiveness, this greatly increases the danger during tire processing. To address this issue, the industry has conducted some experimental explorations.

[0004] Another commonly used silane coupling agent for tires is thiooctanopropyltriethoxysilane, which introduces octyl alkane into its structure, enhancing the dispersibility of silane in silica. However, its synthesis requires octanoyl chloride as a raw material, which decomposes rapidly into octanoic acid and hydrochloric acid when exposed to air, seriously endangering human health. At the same time, its inherent ethoxy group does not avoid the VOC emission problem during tire production.

[0005] The US patent describes another sulfur-containing silane polymer that uses thiooctanoylpropyltriethoxysilane and mercaptopropyltriethoxysilane as raw materials and uses alcohols for chain extension to synthesize a large molecular weight silane polymer. This solves the VOC emission problem in the production process. However, on the one hand, the raw materials used are expensive, and on the other hand, the synthesis process is unstable. After the reaction, an alkaline substance such as sodium ethoxide is needed for catalyst neutralization. Some thiooctanoylpropyltriethoxysilane will decompose in the presence of the catalyst, resulting in poor batch stability of the product. Summary of the Invention

[0006] To address the VOC emissions problem in tire manufacturing processes and the low production efficiency and high price of silane coupling agents, the present invention aims to provide a low-VOC silane polymer for tire processing and its synthesis method.

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] A method for synthesizing a low-VOC silane polymer for tire processing, wherein the silane polymer is synthesized by transesterification reaction using two materials, a and b, as follows:

[0009] a):

[0010]

[0011] Where n is 1 to 4, and n is the average sulfur content of the mixture, which may not be an integer; preferably, n = 1, 2, 3, 4;

[0012] Preferably, a) the component is Si-69 or Si-75;

[0013] b):

[0014]

[0015] Where M is a methyl or hydroxyl group, and at least one end is a hydroxyl group, and m and n are integers from 0 to 15 (e.g., 0, 1, 5, 10, 13, 15, etc.), and are not both 0;

[0016] The preparation process includes: first, adding a compound containing component a) into the reactor, raising the reaction temperature to 60-80°C, adding a catalyst into the reaction solution, then slowly adding component b), maintaining the reaction temperature at 60-80°C, the pressure at 0-300 mbar, preferably 100-250 mbar, and reacting for 2-3 hours.

[0017] In the method of the present invention, hydrogen sulfide is continuously introduced during the reaction process to promote the breaking of polysulfide bonds in component a), thereby improving the reactivity of the product; preferably, the molar amount of hydrogen sulfide introduced per hour is 4-16% of the molar amount of component a).

[0018] Furthermore, the amount of component b) added in the reaction should be determined according to the number of its hydroxyl groups, and the calculation formula is: number of hydroxyl groups in component b * molar amount of component b = molar amount of component a * 3.5;

[0019] Furthermore, the catalyst added to the reaction is a titanate (such as tetrabutyl titanate) or sulfuric acid;

[0020] When using titanate, the catalyst mass is 0.5%-1.4% of the total reactant mass; when using concentrated sulfuric acid, the mass is 0.3%-0.5% of the total reactant mass.

[0021] Furthermore, after the reaction is complete, the product needs to be filtered.

[0022] This invention also relates to the application of the silane polymer prepared above, for use in the preparation of tire rubber products.

[0023] A tire rubber product, using the aforementioned silane polymer as a coupling agent and mixing the rubber using an internal mixer.

[0024] Compared with the prior art, the outstanding effect of the present invention is as follows:

[0025] This invention utilizes transesterification to react polyethers or polyether polyols with a series of inexpensive sulfur-containing silanes such as Si-69 and Si-75, significantly reducing or eliminating the amount of ethanol produced during the rubber vulcanization stage and ensuring production safety. Simultaneously, using polyether molecules to react with the corresponding sulfur-containing silanes effectively improves the dispersibility of silica on rubber molecules, enhancing the mixing effect. The resulting tire rubber products can better balance wet grip and rolling resistance. Detailed Implementation

[0026] The following examples further illustrate the synthesis method of the low-VOC silane polymer for tire processing according to the present invention.

[0027] Comparative Example 1

[0028] 3-Thiooctanoylpropyltriethoxysilane (293.5 g, 0.81 mol) and 3-mercaptopropyltriethoxysilane (32.6 g, 0.12 mol) were added to a round-bottom flask. Sulfuric acid (0.29 g) was added to the reaction flask, and 2-methyl-1,3-propanediol (254.6 g, 2.82 mol) was added through a funnel. The flask was heated to 50 °C under a vacuum of 50 Torr. Ethanol (112.7 g) was collected, and a 21% ethanol solution of sodium ethoxide (0.73 g) was added to obtain the product, designated S-1.

[0029]

Example 1

[0030] Si-69 (300g, 0.56mol) was added to a round-bottom flask, and the reaction temperature was increased to 75°C. Tetrabutyl titanate (6g) was added to the flask, and isomeric tridecyl alcohol polyoxyethylene ether (ES-1305, 825g, 1.96mol) was added through a liquid funnel. The reaction temperature was maintained at 75°C, and hydrogen sulfide gas was introduced during the reaction, with a flow rate of 10mL / min. At the same time, the vacuum pump was turned on to maintain the system pressure at 200mbar. The isomeric tridecyl alcohol polyoxyethylene ether (ES-1305) was added dropwise over a period of about 1 hour. After the addition was completed, the reaction was continued for another 2 hours. After the reaction was completed, the product was filtered through a 20μm filter membrane and the product was recovered. The product code was A-1.

[0031]

Example 2

[0032] Si-69 (300g, 0.56mol) and Si-75 (200g, 0.41mol) were added to a round-bottom flask, and the reaction temperature was increased to 70℃. Tetrabutyl titanate (12g) was added to the reaction flask, and isomeric decayl alcohol polyoxyethylene ether (ES-1003) (988g, 3.395mol) was added through a funnel. The reaction temperature was maintained at 70℃, and hydrogen sulfide gas was introduced during the reaction, with a flow rate of 18mL / min. At the same time, the vacuum pump was turned on to maintain the system pressure at 200mbar. The isomeric decayl alcohol polyoxyethylene ether (ES-1003) was added dropwise over a period of about 1 hour. After the addition was completed, the reaction was continued for another 2 hours. After the reaction was completed, the product was filtered through a 20μm filter membrane and the product was recovered. The product code was A-2.

[0033]

Example 3

[0034] Si-69 (300g, 0.56mol) and Si-75 (200g, 0.41mol) were added to a round-bottom flask, and the reaction temperature was increased to 75°C. Concentrated sulfuric acid (4g) was added to the reaction flask, and polyethylene glycol (PEG400) (679g, 1.6975mol) was added through a funnel. The reaction temperature was maintained at 75°C, and hydrogen sulfide gas was introduced during the reaction, with a flow rate of 24mL / min. At the same time, the vacuum pump was turned on to maintain the system pressure at 200mbar. The polyethylene glycol (PEG400) was added dropwise over a period of about 1 hour. After the addition was completed, the reaction was continued for another 2 hours. After the reaction was completed, the product was filtered through a 20μm filter membrane and the product was recovered. The product code was A-3.

[0035] Using the silica and rubber formulation shown in the table below, the mixture is compounded in a slow internal mixer. First, 60% styrene-butadiene rubber and all other raw materials are added to the mixer and mixed at 110°C for 9 minutes to make a masterbatch. Then, the remaining styrene-butadiene rubber is added, and the temperature is maintained at 110°C for 6 minutes. After that, the material is discharged, pressed into sheets, cooled, and left to stand to form rubber.

[0036]

[0037]

[0038] The test data for the obtained rubber tires are shown in the table below:

[0039]

[0040] Among them, dynamic viscoelastic performance testing was used to characterize the tire's anti-slip performance and rolling resistance performance. The instruments used were a dynamic modulus meter and a viscoelastic spectrometer. Under the action of periodic external force, the dynamic modulus and loss factor (tanδ) were characterized.

[0041] Generally, we characterize tanδ(0℃) as the anti-slip performance. The higher the value, the greater the tire friction, the less likely the tire is to slip, and the better the product's anti-slip performance. On the other hand, we characterize tanδ(60℃) as the tire's rolling resistance. The lower the value, the less resistance the tire generates, the more fuel-efficient it is, and the better the rolling resistance performance.

[0042] Compared to the previous example, tires produced using this patent can better balance wet grip performance and rolling resistance, resulting in superior application performance.

[0043] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A silane polymer, said silane polymer being obtained by reacting two components, a and b, wherein, b) The amount of each component fed and the number of its hydroxyl groups satisfy the following condition: Number of hydroxyl groups in component b * Molar amount of component b = Molar amount of component a * 3.5 a）： Where n is 1 to 4, and n is the average sulfur content of the mixture, which may not be an integer; b）: Where M is methyl or hydroxyl, and at least one end is hydroxyl, and m and n are integers from 0 to 15.

2. The silane polymer according to claim 1, wherein, a) The composition is Si-69 or Si-75.

3. The silane polymer according to claim 1 or 2, wherein the preparation process comprises: First, add component a) to the reactor to increase the reaction temperature. Then, add a catalyst to the reaction solution. Next, slowly add component b) while maintaining the reaction temperature.

4. The silane polymer according to claim 3, wherein, The reaction temperature is 60-80℃ and the pressure is 0-300mbar.

5. The silane polymer according to claim 4, wherein, The pressure is 100-250 mbar.

6. The silane polymer according to claim 3, wherein, Hydrogen sulfide is continuously introduced during the reaction; the molar amount of hydrogen sulfide introduced per hour is 4-16% of the molar amount of component a).

7. The silane polymer according to claim 3, wherein, The catalyst is titanate or concentrated sulfuric acid.

8. The silane polymer according to claim 7, wherein, The titanate is tetrabutyl titanate.

9. The silane polymer according to claim 7, wherein, When using titanate, the mass of the catalyst is 0.5%-1.4% of the total reactant mass; when using concentrated sulfuric acid, the mass is 0.3%-0.5% of the total reactant mass.

10. The use of the silane polymer according to any one of claims 1-9 for the preparation of tire rubber products.

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