A method for preventing the formation of amine oil in the production accelerator CBS

Abstract

This invention belongs to the field of fine chemical product manufacturing, and specifically relates to a method for preventing the formation of amine oil in the production of the accelerator CBS. The method for recovering cyclohexylamine during the CBS accelerator production process uses MBT, cyclohexylamine, and sodium hypochlorite as raw materials. The cyclohexylamine recovery method involves adding sodium sulfate and nonylphenol polyoxyethylene ether, followed by air purging. The recovered cyclohexylamine is reused, added in a specific ratio with fresh cyclohexylamine for the production of CBS accelerator. This effectively prevents the formation of amine oil during CBS production, avoiding the problems of decreased product melting point, increased methanol insoluble matter and free amine, and increased cyclohexylamine consumption caused by amine oil formation. This invention has a simple operating process, significant effects, and is easy to implement industrially, making it suitable for widespread use in actual factory production.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical product manufacturing, and specifically relates to a method for preventing the formation of amine oil in the production accelerator CBS. Background Technology

[0002] CBS, a vulcanization accelerator, is a widely used delayed-action vulcanization accelerator both domestically and internationally. It combines excellent anti-scorching properties with a short vulcanization time, and is mainly used in the manufacture of tires, hoses, rubber shoes, and wires. Furthermore, it does not produce carcinogenic nitrosamines during the vulcanization process, making it one of the most commonly used environmentally friendly accelerators worldwide.

[0003] Currently, the main method for producing CBS (Cumulative Blotching Accelerator) in the industry is the sodium hypochlorite oxidation method. Cyclohexylamine is fed in a large proportion, and unreacted cyclohexylamine is recovered and reused in CBS production; this recovered cyclohexylamine is called recycled cyclohexylamine. The cyclohexylamine used for the first time is called fresh cyclohexylamine. During large-scale CBS production, an oily layer floats on top of the mixture, leading to a decrease in the quality of the produced CBS, a lower melting point, increased methanol-insoluble matter and free amines, and increased cyclohexylamine consumption, posing significant risks to production. For many years, researchers have focused on preventing the formation of amine oil during CBS production, but a suitable method has not yet been found. How to prevent the formation of amine oil during CBS production has become a technical challenge. Summary of the Invention

[0004] This invention addresses the problem of amine oil formation during CBS production by proposing a novel method to prevent the formation of amine oil in the production accelerator CBS.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] A method for recovering cyclohexylamine during the production of accelerator CBS. The production of accelerator CBS uses MBT, cyclohexylamine and sodium hypochlorite as raw materials. The method for recovering cyclohexylamine is as follows: sodium sulfate and nonylphenol polyoxyethylene ether are added, and air is introduced to obtain recovered cyclohexylamine.

[0007] As a preferred option, the amount of sodium sulfate used is 5-20g per liter of recovered cyclohexylamine, and the amount of nonylphenol polyoxyethylene ether used is 0.1-2g; the time for purging air is 1-6h.

[0008] Preferably, the amount of cyclohexylamine recovered per mole of MBT used in the method described in claim 1 or 2 is 400-700 mL, and the amount of fresh cyclohexylamine used is 100-250 mL. The production process is as follows: sodium sulfate and nonylphenol polyoxyethylene ether are added to the recovered cyclohexylamine, and air is introduced; MBT and water are mixed, and the recovered cyclohexylamine and fresh cyclohexylamine are added under stirring, and sodium hypochlorite is added dropwise to carry out the oxidation reaction; after the oxidation endpoint, the mixture is washed with water and dried to obtain the rubber accelerator CBS.

[0009] Preferably, the oxidation reaction temperature is 20-65℃.

[0010] As a preferred option, the sodium sulfate is industrial sodium sulfate.

[0011] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0012] 1. The proposed method of this invention involves adding sodium sulfate and nonylphenol polyoxyethylene ether to recycled cyclohexylamine, purging with air, and reusing the treated recycled cyclohexylamine. It is then used in conjunction with fresh cyclohexylamine in a certain proportion to produce the accelerator CBS. This effectively prevents the generation of amine oil during CBS production, avoiding the problems of decreased product melting point, increased methanol insoluble matter and free amine, and increased cyclohexylamine consumption caused by the generation of amine oil.

[0013] 2. The processing technology of this invention is simple to operate, has significant effects, and is easy to implement in industrial settings, making it suitable for promotion and use in actual factory production. Attached Figure Description

[0014] Figure 1 This is a photograph of the product from Example 1 after it has been left to stand.

[0015] Figure 2 This is a photograph of the product of Comparative Example 1 after it has been left to stand. Detailed Implementation

[0016] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0017] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0018] Example 1

[0019] The recovered cyclohexylamine used in this embodiment and the following embodiments refers to the cyclohexylamine to be reused, which is separated from the product obtained from the industrial production process of the accelerator CBS. The industrial production process of the accelerator CBS and the recovery of cyclohexylamine are already very mature existing processes, and will not be described in detail in this embodiment. The main components of the recovered cyclohexylamine are cyclohexylamine and water.

[0020] Add 8g of sodium sulfate and 0.1g of nonylphenol polyoxyethylene ether to 1L of recovered cyclohexylamine. Place the aerator connected to a blower into the recovered cyclohexylamine and purge with air for 3 hours. Add 40g of accelerator MBT and 60ml of water to a three-necked flask equipped with a stirrer, thermometer, and water bath. Start stirring at 150 rpm for 10 minutes. Then slowly add 120ml of treated recovered cyclohexylamine and 40ml of fresh cyclohexylamine. Stir for 10 minutes, then adjust the water bath temperature to 30-60℃. Add sodium hypochlorite dropwise. Near the endpoint, use a mixture of starch, potassium iodide, and ammonium sulfate for endpoint detection. A blue color indicates the endpoint. Stop the reaction and let it stand at room temperature for 30 minutes. Observe the mixture; no oily substance should precipitate (see Appendix). Figure 1 The product is a CBS accelerator, which is obtained by washing and drying. The product has a melting point of 99.8℃, 0.12% methanol insoluble matter, and 0.25% free amine. The mother liquor and wash water are distilled to recover cyclohexylamine. The cyclohexylamine consumption is 388 kg per ton of CBS product.

[0021] Example 2

[0022] Add 12g of sodium sulfate and 0.3g of nonylphenol polyoxyethylene ether to 1L of recovered cyclohexylamine, and purge with air for 2 hours. Add 40g of accelerator MBT and 60ml of water to a three-necked flask equipped with a stirrer, thermometer, and water bath. Start stirring at 150 rpm for 10 minutes. Slowly add 120ml of treated recovered cyclohexylamine and 40ml of fresh cyclohexylamine, and stir for 10 minutes. At a temperature of 30-60℃, add sodium hypochlorite dropwise. Near the endpoint, use a mixture of starch, potassium iodide, and ammonium sulfate for endpoint detection; a blue color indicates the endpoint. Stop the reaction and let it stand at room temperature for 30 minutes. Observe the mixture; no oily substance should precipitate. Wash with water and dry to obtain the accelerator CBS product. The melting point is 99.6℃, methanol-insoluble matter is 0.11%, and free amine is 0.23%. Distill the resulting mother liquor and wash water to recover cyclohexylamine. The cyclohexylamine consumption is 387kg per ton of CBS product.

[0023] Example 3

[0024] Add 12g of sodium sulfate and 0.3g of nonylphenol polyoxyethylene ether to 1L of recovered cyclohexylamine, and purge with air for 2 hours. Add 200g of accelerator MBT and 300ml of water to a three-necked flask equipped with a stirrer, thermometer, and water bath. Start stirring at 150 rpm for 10 minutes. Slowly add 600ml of treated recovered cyclohexylamine and 200ml of fresh cyclohexylamine, and stir for 10 minutes. At a temperature of 30-60℃, add sodium hypochlorite dropwise. Near the endpoint, use a mixture of starch, potassium iodide, and ammonium sulfate for endpoint detection; a blue color indicates the endpoint. Stop the reaction and let it stand at room temperature for 30 minutes. Observe the mixture; no oily substance should precipitate. Wash with water and dry to obtain the accelerator CBS product. The melting point is 100.1℃, methanol-insoluble matter is 0.10%, and free amine is 0.27%. Distill the resulting mother liquor and wash water to recover cyclohexylamine. The cyclohexylamine consumption is 385kg per ton of CBS product.

[0025] In the actual production process, the original process involved adding the accelerator MBT and water to a preparation tank, stirring them evenly, and then pumping them into a jacketed reactor equipped with a stirrer and thermometer. Recovered cyclohexylamine and fresh cyclohexylamine were slowly added in a specific ratio. At a temperature of 30-60℃, sodium hypochlorite was added dropwise to the reactor. Near the endpoint, a mixture of starch, potassium iodide, and ammonium sulfate was used for endpoint detection; a blue color indicated the endpoint, at which point the reaction was stopped. The mixture was then separated into solid and liquid phases, washed with water, and dried to obtain the accelerator CBS product. The mother liquor and wash water separated in the original production process were distilled to recover cyclohexylamine. Sodium sulfate and nonylphenol polyoxyethylene ether were then added to the recovered cyclohexylamine according to the method proposed in this invention. An aeration head connected to a blower was placed in the recovered cyclohexylamine, and air was introduced for 3 hours to obtain the treated recovered cyclohexylamine. This treated cyclohexylamine could then be reused by adding it in the original ratio of recovered to fresh cyclohexylamine, without requiring any changes to the original equipment.

[0026] Comparative Example 1

[0027] In this embodiment, the recovered cyclohexylamine is used directly without further processing. The amounts of other materials and the preparation process are the same as in Example 1. After the oxidation reaction is complete, the mixture is allowed to stand at room temperature for 30 minutes. The results are as follows: Figure 2 ,from Figure 2 Amine oil was clearly produced. Tests showed that the melting point of the accelerator CBS produced in this comparative example was significantly lower than that in Example 1, and the consumption of methanol-insoluble matter, free amine, and cyclohexylamine all increased.

[0028] Comparative Example 2

[0029] This comparative example of cyclohexylamine recovery does not involve the addition of sodium sulfate; the amounts of other materials and the preparation process are the same as in Example 1. After the oxidation reaction product was allowed to stand at room temperature for 30 minutes, amine oil was clearly observed to be produced. Testing revealed that the melting point of the produced accelerator CBS product was significantly lower than that of Example 1, and the consumption of methanol-insoluble matter, free amine, and cyclohexylamine all increased.

[0030] Comparative Example 3

[0031] The recycled cyclohexylamine used in Comparative Example 1 was not mixed with nonylphenol polyoxyethylene ether, and the other preparation conditions were the same as in Example 1. After the oxidation reaction was completed, the product was left to stand at room temperature for 30 minutes, during which amine oil was produced. The melting point of the produced accelerator CBS product was also lower than that in Example 1, and the consumption of methanol-insoluble matter, free amine, and cyclohexylamine all increased.

[0032] Comparative Example 4

[0033] Compared with Example 1, no air was introduced into the recovered cyclohexylamine in this comparative example, while the other conditions were the same as in Example 1. After the oxidation reaction was completed, the product was allowed to stand at room temperature for 30 minutes, during which amine oil was observed to be produced. Testing revealed that the melting point of the produced accelerator CBS product was also lower than that of Example 1, and the consumption of methanol-insoluble matter, free amine, and cyclohexylamine all increased.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A process for the treatment of cyclohexylamine recovered during the production of accelerator CBS, which is produced from MBT, cyclohexylamine and sodium hypochlorite, characterized in that, The treatment method of the recycled cyclohexylamine is adding sodium sulfate and nonylphenol polyoxyethylene ether, and introducing air to obtain treated recycled cyclohexylamine.

2. The process for the recovery of cyclohexylamine in the production of the accelerator CBS according to claim 1, characterized in that, The amount of sodium sulfate is 5-20 g per liter of recycled cyclohexylamine, and the amount of nonylphenol polyoxyethylene ether is 0.1-2 g per liter of recycled cyclohexylamine; the time for introducing air is 1-6 h.

3. A process for the production of promoter CBS, the production of promoter CBS being carried out using MBT, cyclohexylamine and sodium hypochlorite as raw materials, characterized in that, The amount of treated recycled cyclohexylamine is 400-700 mL per mole of MBT, wherein the treatment method of the recycled cyclohexylamine is adding sodium sulfate and nonylphenol polyoxyethylene ether, and introducing air to obtain treated recycled cyclohexylamine, and the amount of fresh cyclohexylamine is 100-250 mL; the production process is mixing MBT and water, adding treated recycled cyclohexylamine and fresh cyclohexylamine under stirring, and adding sodium hypochlorite dropwise for oxidation reaction; after the oxidation endpoint, washing with water and drying to obtain rubber accelerator CBS.

4. The method of producing the accelerator CBS according to claim 3, characterized by, The oxidation reaction temperature is 20-65℃.

Images