Thiadiazole derivatives, processes for their preparation and use

Abstract

The application discloses a thiadiazole derivative and a preparation method and application thereof, and is obtained by the reaction of 2,5-dithiolate thiadiazole and N-halogenated maleimide. Compared with traditional benzothiazole sulfenamide rubber and plastic accelerators, the compound has the advantages of higher accelerating efficiency, better processing safety and anti-vulcanization reversion performance, avoids the use of 2-mercaptobenzothiazole with a bitter taste, and is more friendly to the production environment, and has good market and economic prospects.

Description

Technical Field

[0001] This invention relates to a novel thiadiazole derivative, its preparation method, and its application in the rubber industry, belonging to the field of fine chemical technology. Background Technology

[0002] Traditional benzothiazole sulfenamide accelerators for rubber and plastics are unstable under normal humid and hot storage conditions, easily decomposing to produce benzothiazole residues. Incomplete reactions can also leave benzothiazole residues, posing a scorching safety hazard during rubber compounding, which is drawing significant attention from tire manufacturers. US Patent 4182873 describes a thiazole sulfenamide accelerator prepared using 2-mercaptothiazole and its derivatives. While this avoids the drawbacks of traditional sulfenamide accelerators that use 2-mercaptobenzothiazole, it, like traditional sulfenamide accelerators, only has one anti-scorching group and one activating group, meaning that issues related to rubber compound processing safety and vulcanization performance still exist.

[0003] Therefore, researching and developing a rubber and plastic accelerator with superior processing safety performance has become an urgent requirement in the current rubber industry. Summary of the Invention

[0004] The purpose of this invention is to provide a thiadiazole derivative, which is obtained by reacting 2,5-dithiol thiadiazole and N-halogenated maleimide. Its molecular structure contains two accelerator groups, two scorch-resistant groups and two active groups. Its processing safety and vulcanization characteristics are superior to those of existing benzothiazole sulfenamide rubber and plastic accelerators.

[0005] The specific technical solution of this invention is as follows: A thiadiazole derivative, the structural formula of which is shown below: Furthermore, the present invention also provides a method for preparing the thiadiazole derivative, which is obtained by reacting the 2,5-dithiol thiadiazole shown in Formula 1 with the N-halogenated maleimide shown in Formula 2; the reaction formula is as follows: Furthermore, in Formula 1, M is sodium or potassium. In Formula 2, X is a halogen, such as chlorine, bromine, or fluorine.

[0006] Furthermore, in the above preparation method, the molar ratio of 2,5-dithiol thiadiazole and N-halogenated maleimide is 1:(2.0-2.2).

[0007] Furthermore, 2,5-dithiol thiadiazole can be purchased from the market or obtained by reacting 2,5-dimercaptothiadiazole with sodium hydroxide or potassium hydroxide, with a molar ratio of 2,5-dimercaptothiadiazole to alkali (sodium hydroxide or potassium hydroxide) of 1:(2-2.05).

[0008] Furthermore, in the above preparation method, N-halogenated maleimide is dissolved in a polar aprotic solvent, 2,5-dithiol thiadiazole is dissolved in water, and then the N-halogenated maleimide solution is added dropwise to the 2,5-dithiol thiadiazole solution to carry out the reaction.

[0009] Furthermore, the polar aprotic solvent is an organic solvent such as DMF (N,N-dimethylformamide), tetrahydrofuran (THF), N,N-diethylformamide (DEF), or dimethyl sulfoxide (DMSO). The amount of solvent used can be adjusted as needed.

[0010] Furthermore, in the above preparation method, the reaction temperature is 0-25℃, such as 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, etc.

[0011] Furthermore, the N-halogenated maleimide solution is added dropwise over a period of 0.5-3 hours, for example, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours. After the addition is complete, the reaction is continued at the specified temperature for another 0.5-1 hour.

[0012] Furthermore, in the above preparation method, after the reaction is completed, a filter cake is obtained by filtration, and the filter cake is washed and dried to obtain the final product.

[0013] Compared with traditional benzothiazole sulfenamide rubber and plastic accelerators, the thiadiazole derivatives of this invention have advantages such as higher acceleration efficiency, better processing safety and resistance to reversion. Therefore, their application in the rubber field is also within the scope of protection.

[0014] Furthermore, the present invention also provides the application of the above-mentioned thiadiazole derivatives as rubber additives.

[0015] The present invention has the following beneficial effects: 1. This invention uses 2,5-dithiol thiadiazole instead of benzothiazole as a raw material, which avoids the bitterness of benzothiazole, makes the production environment more environmentally friendly, and has higher reactivity.

[0016] 2. The thiadiazole derivative of this invention contains two promoting groups, two anti-scorching groups, and two active groups in its molecular structure, resulting in excellent accelerator efficiency, processing safety, and vulcanization characteristics. It is not easily decomposed under normal humid and hot storage conditions, and the product exhibits excellent storage stability. The 2,5-dimercaptothiazole produced during rubber processing can connect with free radicals generated by rubber double bonds at both ends to form sulfur-carbon bonds, thus having a similar effect to vulcanizing agents and reversion agents.

[0017] 3. The thiadiazole derivative of this invention has a simple structure and a simple and easy preparation process. Compared with traditional benzothiazole sulfenamide accelerators, it has superior performance and has broad application and development prospects. Detailed Implementation

[0018] The present invention will be described in detail below through specific embodiments. However, the uses and purposes of these exemplary embodiments are only for illustrating the present invention and do not constitute any limitation on the actual protection scope of the present invention, nor are they intended to limit the protection scope of the present invention to these embodiments.

[0019] In the following examples, product yield = product mass / (molar amount of 2,5-dimercaptothiadiazole) (Product molecular weight) 100.

[0020] Example 1 First, 22.54 g (0.15 mol) of 2,5-dimercaptothiadiazole (molecular weight M = 150.25) and 62 g of 20% sodium hydroxide solution were dissolved in a reaction vessel by stirring and cooling to 5 °C. Then, 54.1 g (0.31 mol) of N-bromomaleimide (molecular weight M = 175.98) was dissolved in 400 g of DMF and transferred to a constant pressure dropping funnel. The N-bromomaleimide solution was then added dropwise to the reaction vessel, maintaining the temperature of the material in the vessel at 5 °C ± 1 °C for 1.5 hours. After the addition was complete, the reaction was maintained at this temperature for half an hour. The mixture was then filtered, the filter cake was washed with water, and then vacuum dried at 80 °C to obtain 48.92 g (molecular weight M = 340.41) of product (yield 95.8%) with a purity (HPLC) of 98.6%.

[0021] Example 2 First, 15 g (0.1 mol) of 2,5-dimercaptothiadiazole (molecular weight M = 150.25) and 40 g of 20% sodium hydroxide solution were dissolved in a reaction vessel by stirring and cooling to 10 °C. Then, 36.56 g (0.21 mol) of N-bromomaleimide (molecular weight M = 175.98) was dissolved in 300 g of DMSO and transferred to a constant pressure dropping funnel. The N-bromomaleimide solution was then added dropwise to the reaction vessel, maintaining the temperature of the material in the vessel at 10 °C ± 1 °C during the addition process. The addition time was 1 hour, and after the addition was completed, the reaction was kept at this temperature for half an hour. The mixture was then filtered, the filter cake was washed with water, and then vacuum dried at 80 °C to obtain 31.69 g (molecular weight M = 340.41) of the present invention sample (yield 93.1%), with a purity (HPLC) of 98.0%.

[0022] Example 3 First, 30.05 g (0.2 mol) of 2,5-dimercaptothiadiazole (molecular weight M = 150.25) and 82 g of 20% sodium hydroxide solution were dissolved in a reaction vessel by stirring and cooling to 0 °C. Then, 73.91 g (0.42 mol) of N-bromomaleimide (molecular weight M = 175.98) was dissolved in 550 g of tetrahydrofuran and transferred to a constant pressure dropping funnel. The N-bromomaleimide solution was then added dropwise to the reaction vessel, maintaining the temperature of the material in the vessel at 0 °C ± 1 °C for 3 hours. After the addition was complete, the reaction was kept at this temperature for half an hour. The mixture was then filtered, the filter cake was washed with water, and then vacuum dried at 80 °C to obtain 63.72 g (molecular weight M = 340.41) of the present invention sample (yield 93.6%), with a purity (HPLC) of 98.2%.

[0023] Example 4 First, 22.54 g (0.15 mol) of 2,5-dimercaptothiadiazole (molecular weight M = 150.25) and 86 g of 20% potassium hydroxide solution were dissolved in a reaction vessel by stirring and cooling to 20 °C. Then, 54.1 g (0.31 mol) of N-bromomaleimide (molecular weight M = 175.98) was dissolved in 400 g of DMF and transferred to a constant pressure dropping funnel. The N-bromomaleimide solution was then added dropwise to the reaction vessel, maintaining the temperature of the material in the vessel at 20 °C ± 1 °C during the addition process. The addition time was 2 hours. After the addition was completed, the reaction was kept at this temperature for half an hour. The mixture was then filtered, the filter cake was washed with water, and then vacuum dried at 80 °C to obtain 47.33 g (molecular weight M = 340.41) of the present invention sample (yield 92.7%), with a purity (HPLC) of 97.4%.

[0024] Performance Applications The application of the sample prepared in Example 1 of this invention and the commercially available rubber and plastic accelerator NS in all-steel radial truck tires was compared.

[0025] I. Main Raw Materials and Equipment BR9000 and SSBR (products of Qilu Petrochemical Company), accelerator NS (product of Shandong Dongying Dairui New Materials Co., Ltd.).

[0026] 1.5L internal mixer (Germany Valrell GmbH), MDR2000 vulcanizer and MV Mooney viscometer (USA Alpha Corporation); XK-160 open mill (Guangdong Zhanjiang Machinery Factory).

[0027] II. Rubber Compound Formulation Parts by weight: SSBR 100 parts; BR9000 25 parts; carbon black 50 parts; silica 60 parts; silane coupling agent NXT 7.5 parts; sulfur 1.5 parts; accelerator 1.7 parts; zinc oxide 2 parts; stearic acid 3 parts; antioxidant 4020 2 parts; antioxidant RD 1 part; protective wax 2 parts. The accelerator is accelerator NS or the sample from Example 1 of this invention.

[0028] III. Rubber Compound Preparation This rubber compounding process is carried out in two stages: One stage is carried out in an internal mixer, with the following feeding sequence: IV. Sample Performance Testing 1. Mooney scorch characteristics (Mouney scorch time at 127℃, tested according to GB / T1233-92).

[0029] Table 1 As can be seen from the data in Table 1, the Mooney scorch time of the product of this invention is longer than that of the traditional accelerator NS, indicating that it has good processing safety performance.

[0030] 2. Vulcanization characteristics (150℃, tested according to GB / T16584-1996).

[0031] Table 2 As can be seen from the data in Table 2, the vulcanization speed of the product of this invention is better than that of the traditional accelerator NS.

[0032] 3. Resistance to reversion (vulcanization temperature 150℃, t95 point is taken as the test point, the torque reduction ratio of the rubber compound at t95 point (HF) is used to represent the resistance to reversion of the rubber compound. The smaller the ratio, the better the resistance to reversion of the rubber compound.

[0033] MH loss rate = (MF - MH) / (MH - ML) × 100.

[0034] Table 3 As can be seen from the data in Table 3, the anti-sulfurization reversion performance of the product of this invention is superior to that of the traditional accelerator NS.

Claims

1. A thiadiazole derivative, characterized in that: It has the following structural formula: 。 2. A method for preparing the thiadiazole derivative according to claim 1, characterized in that: It is obtained by reacting the 2,5-dithiol salt thiadiazole shown in Formula 1 with the N-halogenated maleimide shown in Formula 2; In Equation 1, M is sodium or potassium; In Equation 2, X is a halogen.

3. The preparation method according to claim 2, characterized in that: The molar ratio of 2,5-dithiol thiadiazole to N-halogenated maleimide is 1:(2.0-2.2).

4. The preparation method according to claim 2, characterized in that: N-Halogenimide was dissolved in a polar aprotic solvent, and 2,5-dithiol thiadiazole was dissolved in water. The N-halogenimide solution was then added dropwise to the 2,5-dithiol thiadiazole solution to carry out the reaction.

5. The preparation method according to claim 4, characterized in that: The polar aprotic solvent is at least one of DMF, tetrahydrofuran, N,N-diethylformamide, and dimethyl sulfoxide.

6. The preparation method according to claim 2 or 4, characterized in that: The reaction temperature is 0-25℃.

7. The preparation method according to claim 4, characterized in that: The N-halogenated maleimide solution was added dropwise over 0.5-3 hours, and the reaction was continued at the temperature for another 0.5-1 hour after the addition was complete.

8. The use of the thiadiazole derivative of claim 1 as a rubber additive.

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