Preparation method of post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate

Abstract

The invention provides a method for preparing a post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate, comprising the following steps: adding 1,6-dichlorohexane, sodium sulfite, sulfur and a catalyst to water, reacting under reflux conditions; after the reaction is completed, cooling to room temperature, adding a precipitating agent for crystallization, and then filtering and drying to obtain a post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate. The preparation method of the present invention has a high yield of obtained products, low industrialization cost, and good use effect. The method of the present invention is a novel synthesis route, and the process operation is simple and safe.

Description

Technical Field

[0001] The invention relates to a preparation method of post-vulcanization stabilizer hexamethylene-1,6-sodium dithiosulfate dihydrate, and belongs to the field of fine chemical synthesis technology. Background Art

[0002] Rubber is the main raw material for rubber products such as tires. Whether it is natural rubber or synthetic rubber, it needs to be vulcanized to form a vulcanized cross-linking network so that the rubber has excellent mechanical and dynamic properties. However, rubber will experience vulcanization reversion during high temperature or long-term vulcanization. Vulcanization reversion will reduce the cross-linking density of the vulcanized rubber, thereby reducing the mechanical and dynamic properties of the vulcanized rubber. As a new type of post-vulcanization stabilizer, hexamethylene-1,6-sodium bisthiosulfate dihydrate has the ability to improve the anti-vulcanization reversion performance of rubber vulcanization. The use of this post-vulcanization stabilizer can keep the vulcanized rubber at a high mechanical and dynamic performance.

[0003] At present, the synthesis process of post-vulcanization stabilizer hexamethylene-1,6-dithiosulfate sodium dihydrate is mainly based on sodium thiosulfate pentahydrate and 1,6-dichlorohexane as raw materials, synthesized in water or alcohol solvent, and then the product is obtained by cooling or alcohol precipitation. For example: Chinese patent document CN103819377A discloses a preparation method of hexamethylene 1,6-dithiosulfate disodium salt dihydrate. It includes the following steps: first add an ethanol aqueous solution with an ethanol content of 50-70% or apply the mother liquor to the reactor, then add sodium thiosulfate pentahydrate and 1.6-dichlorohexane, stir and heat, prepare sodium hydroxide aqueous solution, when no more sodium hydroxide aqueous solution is added, continue to reflux and stir, under low-speed stirring, cool to below 40°C, discharge the material for centrifugal separation, dry, add oil, crush, and package to obtain the finished product of anti-sulfurization reversion agent. Chinese patent document CN100509780A provides a method for preparing a post-vulcanizing agent, hexamethylene 1,6-dithiosulfate disodium salt, dihydrate, which uses sodium thiosulfate, dichlorohexane or dibromohexane as raw materials, ethanol as solvent, and reacts at 60-135°C under reflux and stirring conditions. After the reaction, ethanol is added, and reflux is continued at 70-90°C, then cooled to 60-70°C, water is added, filtered, and a crystallized product is obtained, which is then dried. However, the above preparation method has the following disadvantages: 1. The reaction yield is low, and the industrial yield is generally around 70%; 2. Because the product yield is low, the industrial manufacturing cost is high, which increases the customer's use burden.

[0004] Therefore, developing a synthesis process of disodium thiosulfate with simple preparation method, low cost and high yield and purity has always been the research and development direction of those skilled in the art. For this reason, the present invention is proposed. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a preparation method of post-vulcanization stabilizer hexamethylene-1,6-sodium dithiosulfate dihydrate. The preparation method of the present invention has high product yield, low industrialization cost and good use effect.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate comprises the following steps:

[0008] 1,6-dichlorohexane, sodium sulfite, sulfur and a catalyst are added into water and reacted under reflux conditions; after the reaction is completed, the temperature is cooled to room temperature, a precipitating agent is added for crystallization, and then filtered and dried to obtain a post-vulcanization stabilizer hexamethylene-1,6-sodium dithiosulfate dihydrate.

[0009] Preferably according to the present invention, the molar ratio of 1,6-dichlorohexane to sodium sulfite is 1:(1.8-2.4), and more preferably 1:(2.0-2.4).

[0010] Preferably according to the present invention, the molar ratio of 1,6-dichlorohexane to sulfur is 1:(2.0-2.3), wherein the molar number of sulfur is calculated as S.

[0011] Preferably according to the present invention, the catalyst is KI or KBr, and the added mass of the catalyst is 0.5-1.5% of the mass of 1,6-dichlorohexane.

[0012] Preferably according to the present invention, the mass ratio of 1,6-dichlorohexane to water is 0.05-0.15:1.

[0013] Preferably, according to the present invention, the temperature of the reflux reaction process is controlled at 85-110° C.; and the reaction time is 8-12 h.

[0014] Preferably according to the present invention, the precipitation agent is methanol, ethanol or isopropanol; the added mass of the precipitation agent is 100-200% of the mass of water.

[0015] Preferably according to the present invention, the crystallization time is 1-2 hours; and the drying is performed at 55-65° C. for 3-5 hours.

[0016] The synthetic route of the present invention is as follows:

[0017]

[0018]

[0019] The technical features and beneficial effects of the present invention are as follows:

[0020] 1. The present invention uses 1,6-dichlorohexane, sodium sulfite and sulfur as raw materials, and in the presence of a catalyst, a one-pot method is used to prepare a vulcanization stabilizer hexamethylene-1,6-sodium dithiosulfate dihydrate. The method of the present invention is a new synthetic route with simple and safe process operation. In the method of the present invention, 1,6-dichlorohexane and sodium sulfite undergo a nucleophilic substitution reaction to generate hexamethylene-1,6 sodium disulfite, which then undergoes an addition reaction with sulfur to obtain a vulcanization stabilizer hexamethylene-1,6-sodium dithiosulfate dihydrate. Sodium thiosulfate is not used in the reaction process, which eliminates the occurrence of side reactions such as hexanedithiol, and the process operation is simple, safe and environmentally friendly.

[0021] 2. The method of the present invention has high yield and purity of the product, which improves the yield of the product, reduces the production cost, and solves the cost pressure of customers. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the infrared spectrum of the control sample hexamethylene-1,6-sodium bisthiosulfate dihydrate.

[0023] Figure 2 This is the infrared spectrum of the hexamethylene-1,6-sodium bisthiosulfate dihydrate product obtained in Example 1. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto.

[0025] Meanwhile, the experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents, materials and equipment described are all commercially available unless otherwise specified.

[0026] Example 1

[0027] A method for preparing a post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate comprises the following steps:

[0028] To a 1000mL three-necked flask, 31g of 1,6-dichlorohexane, 55.6g of sodium sulfite, 14.1g of sulfur, 0.3g of potassium iodide and 350g of water were added, a condenser was connected, stirring was started, the temperature was raised to 102°C with an electric heating mantle, the system was refluxed, and the reaction was stirred for 10 hours under reflux. After the reaction was completed, it was naturally cooled to room temperature, 400g of ethanol was added, and the mixture was allowed to stand for crystallization for 1 hour, and then filtered to obtain a white filter cake. The filter cake was dried at 60°C for 4h to obtain 74.4g of white solid hexamethylene-1,6-sodium disodium thiosulfate dihydrate, with a yield of 95.4% and a purity of 99.3%.

[0029] The infrared spectrum of the post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate prepared in this example is as follows: Figure 2 As shown, compared with the infrared spectrum of the control sample ( Figure 1 ) comparison, indicating the successful preparation of the product.

[0030] Example 2

[0031] A method for preparing a post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate is as described in Example 1, except that: the catalyst is 0.3 g potassium bromide, and after drying, 74.2 g of hexamethylene-1,6-sodium bisthiosulfate dihydrate is obtained, with a yield of 95.1% and a purity of 99.4%.

[0032] Example 3

[0033] A preparation method of a post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate is as described in Example 1, except that: the amount of solvent water is 300 g, the precipitating agent is isopropanol, the amount of isopropanol is 500 g, and finally 71.6 g of hexamethylene-1,6-sodium bisthiosulfate dihydrate is obtained, the yield is 91.8%, and the purity is 99.6%.

[0034] Comparative Example 1

[0035] A method for preparing a post-vulcanization stabilizer sodium hexamethylene-1,6-bisthiosulfate dihydrate is the same as Example 1, except that the amount of sodium sulfite added is 37.9 g, and the amount of sulfur added is 9.6 g. Finally, 41.34 g of the product is obtained, with a yield of 53.0% and a purity of 97.6%.

[0036] Comparative Example 2

[0037] A method for preparing a post-vulcanization stabilizer sodium hexamethylene-1,6-bisthiosulfate dihydrate is the same as that in Example 1, except that the temperature during the reflux reaction is controlled at 80° C., and 65.59 g of a product is finally obtained with a yield of 84% and a purity of 97.9%.

[0038] Comparative Example 3

[0039] A method for preparing a post-vulcanization stabilizer sodium hexamethylene-1,6-bisthiosulfate dihydrate is the same as Example 1, except that the amount of sodium sulfite added is 75.6 g, and the amount of sulfur added is 19.2 g. Finally, 67.23 g of the product is obtained, with a yield of 86.1% and a purity of 98.2%.

Claims

1. A method for preparing a post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate, comprising the following steps: 1,6-dichlorohexane, sodium sulfite, sulfur and a catalyst are added into water and reacted under reflux conditions; after the reaction is completed, the temperature is cooled to room temperature, a precipitating agent is added for crystallization, and then filtered and dried to obtain a post-vulcanization stabilizer hexamethylene-1,6-sodium dithiosulfate dihydrate; the molar ratio of the 1,6-dichlorohexane to the sodium sulfite is 1:(1.8-2.4); the molar ratio of the 1,6-dichlorohexane to the sulfur is 1:(2.0-2.3); the catalyst is KI or KBr, and the added mass of the catalyst is 0.5-1.5% of the mass of 1,6-dichlorohexane; the temperature of the reflux reaction process is controlled at 85-110°C; the precipitating agent is methanol, ethanol or isopropanol.

2. The method for preparing the post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate according to claim 1, characterized in that: The molar ratio of 1,6-dichlorohexane to sodium sulfite is 1:(2.0-2.4).

3. The method for preparing the post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate according to claim 1, characterized in that: The mass ratio of the 1,6-dichlorohexane to water is 0.05-0.15:

1.

4. The method for preparing the post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate according to claim 1, characterized in that: The reaction time is 8-12h.

5. The method for preparing the post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate according to claim 1, characterized in that: The added mass of the precipitation agent is 100-200% of the mass of the solvent water.

6. The method for preparing the post-vulcanization stabilizer hexamethylene-1,6-sodium bisthiosulfate dihydrate according to claim 1, characterized in that: The crystallization time is 1-2 hours; the drying is performed at 55-65° C. for 3-5 hours.

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