Low-VOC (volatile organic compound) silane polymer for tire processing and synthesis method of low-VOC silane polymer

Abstract

The invention relates to a low-VOC (volatile organic compound) silane polymer for tire processing and a synthesis method of the low-VOC silane polymer. The method comprises the following steps: mixing long-chain polyether or polyether polyol with sulfur-containing silane, continuously introducing hydrogen sulfide gas, carrying out ester exchange reaction in the presence of a corresponding catalyst, and finally synthesizing the corresponding silane polymer. The silane polymer can effectively improve the dispersion effect of white carbon black in the tire synthesis stage, meanwhile, no VOC gas is generated in the production process, the safety during tire processing can be effectively improved, meanwhile, compared with a traditional sulfydryl silane coupling agent, silane can remarkably balance the wet skid resistance and rolling friction resistance of a tire, and the service life of the tire is prolonged. The application performance of the tire is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silane coupling agents, and in particular to a low-VOC silane polymer for tire processing and a synthesis method thereof. Background Art

[0002] Sulfur-containing silane is an important organosilicon intermediate, mainly used in compounding with precipitated silica to produce "green tires". Compared with carbon black, tires filled with silica have excellent traction performance and wear life while reducing fuel consumption. Therefore, the new generation of low rolling resistance and low fuel consumption "green tires" filled with silica are the mainstream of tire industry development in recent years. However, the surface of precipitated silica contains a large number of hydroxyl groups, which makes it highly acidic, hygroscopic and hydrophilic, and has poor compatibility with rubber. The mixing process will have problems such as prolonged vulcanization time and reduced crosslinking degree. Adding silane coupling agent to modify the surface of silica can reduce the surface polarity of silica and improve its compatibility with rubber.

[0003] The most commonly used silanes in "green tires" are bis-[3-(triethoxysilyl)-propyl]-tetrasulfide (Si-69 or TESPT) and bis-[3-(triethoxysilyl)-propyl]-disulfide (Si-75). However, on the one hand, the polysulfide bonds of the silane coupling agents are terminated by alkoxysilanes during tire processing, which means that the vulcanization time of the tire is relatively long and the processing efficiency is relatively low during the processing. On the other hand, during the high-temperature process of rubber mixing, the ethoxy group will fall off by itself to form volatile ethanol gas, which greatly increases the danger during tire processing due to its own flammability. To solve this problem, the industry has conducted some experimental explorations.

[0004] Another silane coupling agent commonly used in tires is thiooctanoylpropyltriethoxysilane, which introduces octyl alkane into its structure, enhancing the dispersibility of silane in white carbon black. On the other hand, its synthesis process requires the use of octanoyl chloride as a synthetic raw material, which will quickly decompose into octanoic acid and hydrochloric acid when exposed to air, seriously endangering human health. At the same time, its inherent ethoxy group also fails to avoid the VOC emission problem in the tire production process.

[0005] The US patent introduces another sulfur-containing silane polymer, which uses thiooctanoylpropyltriethoxysilane and mercaptopropyltriethoxysilane as raw materials, uses alcohols for chain extension, and synthesizes macromolecular silane polymers, which 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 is completed, alkaline substances such as sodium ethanol are needed to neutralize the catalyst. Part of the thiooctanoylpropyltriethoxysilane will decompose in the presence of the catalyst, resulting in poor batch stability of the product. Summary of the invention

[0006] In order to solve the VOC emission problem in the tire production process on the market and the low production efficiency and high price of silane coupling agents, the purpose of the present invention is to provide a low-VOC silane polymer for tire processing and a synthesis method thereof.

[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 of the following two materials a and b:

[0009] a):

[0010]

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

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

[0013] b):

[0014]

[0015] Wherein M is a methyl group or a hydroxyl group, and at least one end is a hydroxyl group, and m and n are integers of 0-15 (e.g., 0, 1, 5, 10, 13, 15, etc.), and are not 0 at the same time;

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

[0017] In the method of the present invention, further, hydrogen sulfide needs to be continuously introduced during the reaction process to promote the cleavage of the polysulfide bonds of the component a), thereby improving the reaction activity 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 hydroxyl groups thereof, and the calculation formula is: the amount of hydroxyl groups of material b*the molar amount of material b=the molar amount of material a*3.5;

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

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

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

[0022] The present invention also relates to the application of the silane polymer prepared above, which is used for preparing tire rubber products.

[0023] A tire rubber product uses the above-mentioned silane polymer as a coupling agent and uses an internal mixer to mix rubber.

[0024] Compared with the prior art, the outstanding effects of the present invention are:

[0025] The present invention allows polyether or polyether polyol to react with a series of low-cost sulfur-containing silanes such as Si-69 and Si-75 through ester exchange reaction, which can significantly reduce or eliminate the amount of ethanol produced in the rubber vulcanization stage, ensuring the safety of production. At the same time, using polyether molecules to react with corresponding sulfur-containing silanes can effectively improve the dispersibility of white carbon black on rubber molecules and improve the mixing effect. The tire rubber products produced can better balance the wet grip and rolling resistance of the tire. DETAILED DESCRIPTION

[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-Thiocapryloylpropyltriethoxysilane (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 an addition 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, product number S-1.

[0029] [Example 1]

[0030] Si-69 (300 g, 0.56 mol) was added to a round-bottom flask, the reaction temperature was increased to 75°C, tetrabutyl titanate (6 g) was added to the reaction flask, and isomeric tridecanol polyoxyethylene ether (ES-1305, 825 g, 1.96 mol) was added through an addition funnel, the reaction temperature was maintained at 75°C, hydrogen sulfide gas was introduced during the reaction, the flow rate was controlled at 10 mL / min, and the vacuum pump was turned on at the same time to maintain the system pressure at 200 mbar. The isomeric tridecanol polyoxyethylene ether (ES-1305) was added dropwise for about 1 h, and the reaction was continued for 2 h after the addition was completed. After the reaction was completed, the product was filtered using a 20 μm filter membrane to recover the product, product code A-1.

[0031] [Example 2]

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

[0033] [Example 3]

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

[0035] Use the silica and rubber formula shown in the following table and mix them in a slow internal mixer. First, add 60% styrene butadiene rubber and all other raw materials into the internal mixer, mix them at 110°C for 9 minutes to make a masterbatch, then add the remaining styrene butadiene rubber, maintain the temperature at 110°C, mix for 6 minutes, then discharge the materials for tableting, cool, park, and rubber molding.

[0036]

[0037]

[0038] The test data of the obtained rubber tire is shown in the following table:

[0039]

[0040] Among them, the dynamic viscoelastic performance test is used to characterize the anti-skid performance and rolling resistance performance of the tire. The instruments used are dynamic modulus meter and viscoelastic spectrometer. Under the action of periodic external force, the dynamic modulus and loss factor (tanδ) are characterized.

[0041] Usually, we characterize tanδ(0℃) as the anti-skid performance. The higher the value, the greater the tire friction, the less likely the tire is to slip, and the better the anti-skid performance of the product. Tanδ(60℃) is characterized as the rolling resistance of the tire. The lower the value, the smaller the resistance generated by the tire, the more fuel-efficient it is, and the better the rolling resistance performance.

[0042] Compared with the embodiment, the tire produced using this patent can better balance the anti-skid performance and rolling resistance, and has better application performance.

[0043] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A silane polymer, wherein the silane polymer is obtained by reacting the following two components: a and b: a)： Where n is 1 to 4, n is the average sulfur content of the mixture, which may not be an integer; Preferably, a) component is Si-69 or Si-75; b): Wherein M is a methyl group or a hydroxyl group, and at least one end is a hydroxyl group, and m and n are integers of 0-15 respectively.

2. The silane polymer according to claim 1, wherein b) The amount of component fed and its hydroxyl number satisfy the following: hydroxyl number of component b*molar amount of component b fed = molar amount of component a*3.

5.

3. The silane polymer according to claim 1 or 2, wherein the preparation process comprises: First, add component a) into the reactor, increase the reaction temperature, add a catalyst into the reaction solution, then slowly dropwise add component b) and maintain the reaction temperature to react.

4. The silane polymer according to claim 3, wherein b) The amount of component fed and its hydroxyl number satisfy the following: hydroxyl number of component b*molar amount of component b fed = molar amount of component a*3.

5.

5. The silane polymer according to claim 3 or 4, wherein The reaction temperature is 60-80°C, and the pressure is 0-300 mbar, preferably 100-250 mbar.

6. The silane polymer according to any one of claims 3 to 5, wherein Hydrogen sulfide is continuously introduced during the reaction; preferably, 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 any one of claims 3 to 5, wherein The catalyst is titanate (such as tetrabutyl titanate) or concentrated sulfuric acid.

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

9. Use of the silane polymer according to any one of claims 1 to 8 for preparing tire rubber products.

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