Process for the catalytic oxidation preparation of the vulcanization accelerator CBS
By using a combination of Mg2+ and Mn2+ salt catalysts with hydrogen peroxide in the synthesis of CBS, the problem of industrial waste salt pollution was solved, and high-yield, green and environmentally friendly CBS production was achieved, which is suitable for large-scale industrialization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG SUNSINE CHEM
- Filing Date
- 2024-02-01
- Publication Date
- 2026-06-23
Smart Images
Figure SMS_1 
Figure SMS_2
Abstract
Description
Technical Field
[0001] This invention belongs to the field of rubber vulcanization accelerator production technology, and relates to a method for preparing vulcanization accelerator CBS by catalytic oxidation. Background Technology
[0002] CBS (N-cyclohexyl-2-benzothiazole sulfenamide), a rubber vulcanization accelerator, belongs to the sulfenamide class and is a post-effect semi-ultra-fast vulcanization accelerator. It can significantly improve the aging resistance and physical properties of rubber products. It features anti-scorching properties and short vulcanization time. When used in combination with accelerators MBT, TMTD, and MBTS, it can improve the tensile strength and elongation of the vulcanizate. It is particularly suitable for natural rubber, synthetic rubber, and rubber products containing carbon black and reclaimed rubber. It exhibits slight discoloration, no blooming, and excellent aging resistance of the vulcanizate. It is mainly used in the manufacture of tires, rubber shoes, rubber hoses, rubber belts, cables, and general industrial products, and its unique superior properties are highly welcomed by users.
[0003] The main synthesis processes for CBS accelerators include sodium hypochlorite oxidation, oxygen oxidation, hydrogen peroxide oxidation, mixed oxidation, and oxidant-free oxidation. In China, sodium hypochlorite oxidation is the primary method for CBS preparation. This method has a mature process route, is easy to control, has relatively simple equipment requirements, and offers a high yield, currently reaching 94% in industrial production. However, this process generates a large amount of difficult-to-treat industrial waste salt, putting pressure on the environment. Oxygen oxidation is currently a more advanced CBS synthesis process, and oxygen is considered a "green" oxidant. However, the oxygen oxidation process is not yet mature, requiring certain pressure conditions and demanding high equipment sealing, which poses relatively significant safety risks and hinders its industrial application. Oxidant-free oxidation produces CBS accelerators under alkaline conditions. Although the yield is high, the recovery rate of related auxiliary materials is low. The addition of sodium nitrite results in the emission of NO gas, which is highly toxic, pollutes the environment, and is detrimental to safe production. Furthermore, a large amount of Na2SO4 aqueous solution needs to be treated. Therefore, this process has not yet been adopted by manufacturers both domestically and internationally. The mixed oxidation method uses hydrogen peroxide and sodium hypochlorite as oxidants. A certain amount of hydrogen peroxide is added dropwise, and then sodium hypochlorite is used to oxidize to the reaction endpoint. This method can ensure the quality and yield of CBS, but it cannot fundamentally solve the problem of salinity in industrial wastewater.
[0004] The hydrogen peroxide oxidation method for preparing CBS theoretically produces no industrial waste salt, making it a green and environmentally friendly route. However, hydrogen peroxide exhibits poor oxidative selectivity in the later stages of the reaction, resulting in a low product yield and hindering its industrial production. Therefore, finding a clean and green process route that ensures product quality and yield while producing no industrial waste salt has become a top priority for researchers. Summary of the Invention
[0005] This invention proposes a novel, green method for the catalytic oxidation preparation of CBS (sulfurization accelerator) to address the problems existing in traditional CBS industrial production.
[0006] This invention utilizes hydrogen peroxide as the oxidant only during the production process in the presence of a catalyst. The raw materials used in catalyst preparation are inexpensive and readily available, and can be directly used after simple synthesis during production. This process generates no industrial saline wastewater (only a small amount of waste salt is generated during catalyst preparation, which is negligible), facilitates large-scale synthesis of the promoter CBS, and produces high-quality CBS with high yield.
[0007] The process provided by this invention involves the following reaction:
[0008]
[0009] To achieve the above objectives, the present invention is implemented using the following technical solution:
[0010] Step 1: Add a certain mass of water-soluble Mg 2+ Salt and Mn 2+ Salt is placed in a reactor, and a certain amount of distilled water is added. The mixture is stirred until all the solid is dissolved.
[0011] Step 2: Prepare a NaOH solution of a certain concentration and volume. Heat the reactor to bring the liquid to a boil, and then slowly add the prepared NaOH solution dropwise into the reactor. During the dropwise addition, a large amount of precipitate will be produced in the system.
[0012] Step 3: After the addition is complete, cool the suspension to room temperature (the solution must be alkaline according to the pH test paper; otherwise, continue to add sodium hydroxide solution to ensure sufficient precipitation of metal ions), filter, wash the precipitate with distilled water, and then place the precipitate in an oven to dry to constant weight. Grind it into powder in a mortar to obtain the catalyst, which can be used for the catalytic oxidation process in subsequent production processes.
[0013] Step 4: Mix a certain mass of catalyst, accelerator MBT and a certain volume of distilled water in a reaction vessel and stir thoroughly. After mixing evenly, add a certain amount of cyclohexylamine and stir to form M-cyclohexylamine salt.
[0014] Step 5: At a certain temperature, add a certain concentration of hydrogen peroxide solution dropwise into the reactor at a certain rate. Use an indicator to detect the endpoint of the oxidation reaction. Stop adding hydrogen peroxide solution when the oxidation reaction is complete.
[0015] Step 6: Cool the reaction vessel system to room temperature naturally, separate the solid and liquid, wash with water until neutral, place the obtained wet product in an oven to dry, and the finished product CBS is obtained after drying.
[0016] Preferably, in step 1, the water-soluble Mg used is... 2+ Salt, Mn 2+ The salts are MgSO4·7H2O and MnSO4·H2O, with a molar ratio of MgSO4·7H2O to MnSO4·H2O of 5-20:1. The total concentration of the metal salts, C(MgSO4·7H2O) + C(MnSO4·H2O), is 0.4-0.7 mol / L.
[0017] Preferably, in step 2, the concentration of the added alkaline NaOH solution is 1.2-1.4 mol / L, and its molar equivalent is slightly greater than that of Mg. 2+ and Mn 2+ Twice the molar equivalent of Mg 2+ Mn 2+ When precipitation is complete, the total time for adding the alkaline solution dropwise into boiling water is 0.5-1 hour.
[0018] Preferably, in step 3, the drying temperature of the precipitate in the oven is 110°C. o C, drying time is 8-12 hours.
[0019] Preferably, in step 4, the amount of catalyst used accounts for 4-6‰ of the mass of 2-mercaptobenzothiazole, the mass ratio of distilled water to 2-mercaptobenzothiazole is 3-3.5:1, and the mass ratio of cyclohexylamine to MBT is 1.2-1.4:1.
[0020] Preferably, in step 4, distilled water, catalyst, and 2-mercaptobenzothiazole (MBT) are added sequentially to the reactor under stirring and stirred until homogeneous. Then, cyclohexylamine is added to the reactor and slurryed. The temperature is maintained at 30-40°C throughout the entire process. o C. The mixing and beating time is 0.5-1 hour.
[0021] Preferably, in step 5, the hydrogen peroxide concentration is 6-10%. In a typical process, when the total reaction volume is 180-250 ml, the hydrogen peroxide is added at a rate of 25-30 ml / h, the volume ratio of the hydrogen peroxide solution to the mass of MBT is 2.25-3 L / kg, and the reaction temperature is 30-40 °C. o C.
[0022] Preferably, in step 5, the endpoint detection indicator is ammonium sulfate and starch-potassium iodide reagent. A small amount of reaction solution is added to the indicator, and the indicator turns blue, which indicates the reaction endpoint.
[0023] Preferably, in step 6, the solid obtained after solid-liquid separation is placed at 60-70°C. o Dry in an oven at temperature C for 8-12 hours.
[0024] The production of the CBS accelerator according to this invention mainly involves two steps: catalyst preparation and the use of the prepared catalyst to carry out the synthesis reaction of the CBS accelerator. Experimental verification shows that the catalyst in this invention significantly alters the oxidation selectivity of hydrogen peroxide, thereby improving the yield of the CBS product.
[0025] Compared with the prior art, the advantages and positive effects of the present invention are as follows:
[0026] 1. This invention, using only hydrogen peroxide as an oxidant in the presence of a small amount of catalyst, significantly improves the yield of CBS compared to the case without using a catalyst, without altering the quality of the CBS product.
[0027] 2. This invention uses only hydrogen peroxide as an oxidant and does not use sodium hypochlorite. Therefore, the industrial wastewater produced does not contain salt, and no industrial waste salt is produced (only a small amount of waste salt is produced during the catalyst production process, which can be ignored). It belongs to green process production.
[0028] 3. This invention uses only hydrogen peroxide as an oxidant, and its yield of the accelerator CBS is almost equivalent to the current industrial yield of CBS using sodium hypochlorite as an oxidant (or the yield of CBS using a mixed oxidation method), showing potential for large-scale industrial production.
[0029] 4. The entire operation process is relatively simple, the conditions are mild, and it is an environmentally friendly process, which is conducive to large-scale industrialization. Detailed Implementation
[0030] 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.
[0031] 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.
[0032] Example 1
[0033] This embodiment provides a method for catalyst preparation and CBS (sulfurization accelerator) production.
[0034] The catalyst preparation process was as follows: 100 ml of distilled water was added to a 500 ml four-necked flask, followed by the sequential addition of 12.335 g of MgSO4·7H2O and 0.423 g of MnSO4·H2O. The mixture was stirred at 200 rpm and heated to boiling until all the solids were dissolved. 4.29 g of solid NaOH was weighed and dissolved in 80 ml of distilled water. After complete dissolution, the alkali solution was slowly added dropwise to a boiling magnesium-manganese salt solution over 40 minutes. After the addition was complete, the resulting suspension was cooled to room temperature, and the precipitate was filtered out and placed at 110 °C. o The solid was dried in an oven for 10 hours, and then ground into powder in a mortar to obtain catalyst A.
[0035] Add 130 ml of distilled water and 0.2 g of catalyst A to a 500 ml three-necked flask and stir thoroughly. Place the entire reaction system at 35°C. o In a water bath at C, maintain a constant temperature. Then add 40g of MBT, stir well, and then quickly add 52g of cyclohexylamine dropwise over 1-2 minutes. After the addition is complete, stir and beat at 200-300 rpm for 40 minutes.
[0036] After homogenizing the pulp, slowly add an 8% hydrogen peroxide solution dropwise to the reaction system at a rate of 25-30 ml / h, and maintain the reaction temperature at 35°C throughout the entire addition process. o Around C. After about 4 hours of dripping, take a sample every 5 minutes and test the reaction system with ammonium sulfate and starch-potassium iodide indicators. If the indicator turns blue, the reaction is complete and the dripping should be stopped.
[0037] After stopping the dropwise addition for 10 minutes, rinse the outside of the three-necked flask with running tap water and cool the reaction system until the temperature drops to 20°C. o When the temperature is below 65°C, solid-liquid separation is performed by filtration, and the resulting solid product is washed with distilled water until neutral. The product is then placed at 65°C. o The product was dried in an oven at temperature C for 10 hours. After drying, it was weighed to obtain 59.33 g of rubber accelerator CBS, with a yield of 93.81%.
[0038] Example 2
[0039] This embodiment provides a method for preparing the catalyst and producing the sulfidation accelerator CBS. Unless otherwise specified, the preparation process is the same as in Example 1.
[0040] Add 100ml of distilled water to a 500ml four-necked flask, then add 12.335g of MgSO4·7H2O and 0.564g of MnSO4·H2O in sequence. Stir and heat to boiling to dissolve all the solids.
[0041] Weigh 4.37g of NaOH and dissolve it in 80ml of distilled water. After it is completely dissolved, slowly add the alkali solution dropwise to the boiling magnesium and manganese salt solution. The dropwise addition process takes 40 minutes.
[0042] After the addition was complete, the suspension was cooled to room temperature, the precipitate was filtered out, and placed at 110 °C. o The solid was dried in an oven for 10 hours, and then ground into powder in a mortar. This is the catalyst B.
[0043] Add 130 ml of distilled water and 0.2 g of catalyst B to a 500 ml three-necked flask, stir thoroughly, and maintain the entire reaction system at 35 °C. o Place the mixture in a water bath at C. Then add 40g of MBT, stir well, and then quickly add 52g of cyclohexylamine, and beat for 40 minutes.
[0044] After homogenizing the pulp, slowly add an 8% hydrogen peroxide solution dropwise to the reaction system at a rate of 25-30 ml / h, and maintain the reaction temperature at 35°C throughout the entire addition process. o Around C. After about 4 hours of dripping, use ammonium sulfate and starch-potassium iodide indicators to check the reaction system. If the indicator turns blue, the reaction has reached its endpoint, and dripping should be stopped.
[0045] Ten minutes after stopping the droplet addition, the reaction system was cooled. When the temperature dropped to 20°C... o Below 65°C, perform solid-liquid separation and wash the resulting product with distilled water until neutral. Then place the product at 65°C. o The product was dried in an oven at temperature C for 10 hours. After drying, 59.51 g of rubber accelerator CBS was obtained, with a yield of 94.10%.
[0046] Example 3
[0047] This embodiment provides a method for preparing the catalyst and producing the sulfidation accelerator CBS. Unless otherwise specified, the preparation process is the same as in Example 1.
[0048] Add 100ml of distilled water to a 500ml four-necked flask, then add 12.335g of MgSO4·7H2O and 0.845g of MnSO4·H2O in sequence. Stir and heat to boiling to dissolve all the solids.
[0049] Weigh 4.50g of NaOH and dissolve it in 80ml of distilled water. After it is completely dissolved, slowly add the alkali solution dropwise to the boiling magnesium and manganese salt solution. The dropwise addition process takes 40 minutes.
[0050] After the addition was complete, the suspension was cooled to room temperature, the precipitate was filtered out, and placed at 110 °C.o The solid was dried in an oven for 10 hours, and then ground into powder in a mortar. This is the obtained catalyst C.
[0051] Add 130 ml of distilled water and 0.2 g of catalyst C to a 500 ml three-necked flask, stir thoroughly, and maintain the entire reaction system at 35 °C. o Place the mixture in a water bath at C. Then add 40g of MBT, stir well, and then quickly add 52g of cyclohexylamine, and beat for 40 minutes.
[0052] After homogenizing the pulp, slowly add an 8% hydrogen peroxide solution dropwise to the reaction system at a rate of 25-30 ml / h, and maintain the reaction temperature at 35°C throughout the entire addition process. o Around C. After about 4 hours of dripping, use ammonium sulfate and starch-potassium iodide indicators to check the reaction system. If the indicator turns blue, the reaction has reached its endpoint, and dripping should be stopped.
[0053] Ten minutes after stopping the droplet addition, the reaction system was cooled. When the temperature dropped to 20°C... o Below 65°C, perform solid-liquid separation and wash the resulting product with distilled water until neutral. Then place the product at 65°C. o The product was dried in an oven at temperature C for 10 hours. After drying, 59.57 g of rubber accelerator CBS was obtained, with a yield of 94.19%.
[0054] Example 4
[0055] This embodiment provides a method for preparing the catalyst and producing the sulfidation accelerator CBS. Unless otherwise specified, the preparation process is the same as in Example 1.
[0056] Add 100ml of distilled water to a 500ml four-necked flask, then add 12.335g of MgSO4·7H2O and 1.69g of MnSO4·H2O in sequence. Stir and heat to boiling to dissolve all the solids.
[0057] Weigh 4.91g of NaOH and dissolve it in 80ml of distilled water. After it is completely dissolved, slowly add the alkali solution dropwise to the boiling magnesium and manganese salt solution. The dropwise addition process takes 40 minutes.
[0058] After the addition was complete, the suspension was cooled to room temperature, the precipitate was filtered out, and placed at 110 °C. o The solid was dried in an oven for 10 hours, and then ground into powder in a mortar. This is the catalyst D.
[0059] Add 130 ml of distilled water and 0.2 g of catalyst D to a 500 ml three-necked flask, stir thoroughly, and maintain the entire reaction system at 35 °C. oPlace the mixture in a water bath at C. Then add 40g of MBT, stir well, and then quickly add 52g of cyclohexylamine, and beat for 40 minutes.
[0060] After homogenizing the pulp, slowly add an 8% hydrogen peroxide solution dropwise to the reaction system at a rate of 25-30 ml / h, and maintain the reaction temperature at 35°C throughout the entire addition process. o Around C. After about 4 hours of dripping, use ammonium sulfate and starch-potassium iodide indicators to check the reaction system. If the indicator turns blue, the reaction has reached its endpoint, and dripping should be stopped.
[0061] Step 6: After stopping the dropwise addition for 10 minutes, begin cooling the reaction system. When the temperature drops to 20°C... o Below 65°C, perform solid-liquid separation and wash the resulting product with distilled water until neutral. Then place the product at 65°C. o The product was dried in an oven at temperature C for 10 hours. After drying, 59.4 g of rubber accelerator CBS was obtained, with a yield of 93.92%.
[0062] Comparative Example 1
[0063] Unless otherwise specified, the preparation process in this comparative example is the same as that in Example 1.
[0064] Add 130 ml of distilled water to a 500 ml three-necked flask, and maintain the entire reaction system at 35°C. o Place the mixture in a water bath at C. Then add 40g of MBT, stir well, and then quickly add 52g of cyclohexylamine, and beat for 40 minutes.
[0065] After homogenizing the pulp, slowly add an 8% hydrogen peroxide solution dropwise to the reaction system at a rate of 25-30 ml / h, and maintain the reaction temperature at 35°C throughout the entire addition process. o Around C. After about 4 hours of dripping, use ammonium sulfate and starch-potassium iodide indicators to check the reaction system. If the indicator turns blue, the reaction has reached its endpoint, and dripping should be stopped.
[0066] Ten minutes after stopping the droplet addition, the reaction system was cooled. When the temperature dropped to 20°C... o Below 65°C, perform solid-liquid separation and wash the resulting product with distilled water until neutral. Then place the product at 65°C. o The product was dried in an oven at temperature C for 10 hours. After drying, 57.08 g of rubber accelerator CBS was obtained, with a yield of 90.25%.
[0067] Table 1 below shows the quality indicators of the CBS products of various embodiments of the present invention and the comparative embodiment CBS.
[0068] Table 1 Product Quality Inspection Results
[0069]
[0070] As can be seen from the above embodiments, the initial melting point of CBS obtained using the present invention reaches 99. o C. All other quality indicators exceeded national standards. The yield of CBS prepared in this example reached approximately 94%, comparable to the yield of CBS prepared industrially using the sodium hypochlorite oxidation method. Furthermore, the process of this invention is simple, easy to implement, highly operable, and safe, avoiding the use of strong alkalis like sodium hydroxide and hazardous gases like chlorine in sodium hypochlorite production. The entire process generates no industrial waste salt, making it a green and environmentally friendly process, conducive to large-scale industrial production.
[0071] 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. Use of Mg / Mn bimetallic ionic catalyst in the production of rubber accelerator CBS, characterized in that, The preparation process of the Mg / Mn bimetallic ion catalyst is as follows: dissolving soluble magnesium salt and manganese salt in deionized water, heating and boiling, slowly adding sodium hydroxide aqueous solution until precipitation is precipitated; after filtration, drying, grinding into powder to obtain the Mg / Mn bimetallic ion catalyst; The molar ratio of the soluble magnesium salt and the manganese salt is 5-20:1, the total concentration of the soluble magnesium salt and the manganese salt in the deionized water is 0.4-0.7 mol / L, and the concentration of the sodium hydroxide aqueous solution is 1.2-1.4 mol / L.
2. A process for the production of rubber accelerator CBS by catalytic oxidation, characterized in that, The catalyst used in the application of claim 1 is as follows: (1) 2-mercaptobenzothiazole, catalyst is added into distilled water, mixed with cyclohexylamine and stirred uniformly to obtain a mixed reaction liquid; (2) the mixed reaction liquid is heated to 30-40℃, and hydrogen peroxide solution is added dropwise for oxidation reaction; (3) the material obtained by the oxidation reaction is cooled to room temperature, filtered, and the obtained product is washed to neutral, dried to obtain rubber accelerator CBS.
3. The process for the production of rubber accelerator CBS by catalytic oxidation according to claim 2, characterized in that, In step (1), the mass of the catalyst accounts for 4-6‰ of the mass of 2-mercaptobenzothiazole, the mass ratio of distilled water, cyclohexylamine and 2-mercaptobenzothiazole is (3-3.5):(1.2-1.4):1, and the stirring time is 0.5-1 h.
4. The process for the production of rubber accelerator CBS by catalytic oxidation according to claim 2, characterized in that, In step (2), the mass concentration of the hydrogen peroxide solution is 6-10%, the volume of the hydrogen peroxide solution to the mass of 2-mercaptobenzothiazole is 2.25-3L / kg, and in step (3), the drying temperature is 60-70 o C, and the drying time is 8-12h.