JP2009263325A - Novel sulfur supplying vulcanizing agent and vulcanization accelerator for rubber not generating nitrosamine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sulfur supplying vulcanizing agent and delayed effect vulcanization accelerator for a rubber which does not act as a generation source of harmful nitrosamine. <P>SOLUTION: A 2-(dibenzyl amino dithio)benzothiazole represented by the formula is used as a vulcanization accelerator and/or a vulcanizing agent for a rubber. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber vulcanization accelerator and a sulfur-donating vulcanizing agent, and more particularly to a sulfenamide rubber vulcanization accelerator belonging to thiazoles that do not become a source of harmful nitrosamines.

A sulfenamide compound is used as a vulcanization accelerator for rubber and is characterized by imparting a slow effect to the vulcanization reaction, and is generally referred to as a sulfenamide vulcanization accelerator. Rubber has poor thermal conductivity, and it is difficult to uniformly vulcanize it in the production of thick rubber products. In that case, use a sulfenamide-based vulcanization accelerator that gives a slow effect to the vulcanization reaction. Is valid. A sulfenamide vulcanization accelerator having a disulfide structure also functions as a sulfur-donating vulcanization agent, and has better physical properties than the monosulfide sulfenamide vulcanization accelerator. Rubber is obtained.
Specifically, among the commercially available sulfenamide vulcanization accelerators, 2- (4′-morpholinodithio) benzothiazole (abbreviation: MDB) and N-oxydiethylene-2-benzothiazole sulfenamide (abbreviation: OBS) as monosulfide type sulfenamide vulcanization accelerators, both of which contain a morpholine structure. This may be a source of harmful N-nitrosomorpholine (see Non-Patent Documents 1, 2, and 3).

  In addition, Patent Document 1 describes a monosulfide type sulfenamide vulcanization accelerator that does not become a source of harmful nitrosamines, specifically N, N-dibenzylbenzothiazole sulfenamide. Is not described. Non-Patent Document 4 describes that dibenzylamine contained in 2- (dibenzylaminodithio) benzothiazole according to the present invention does not become a source of harmful nitrosamines.

S—N compound as a slow-acting vulcanizing agent (1), Journal of the Japan Rubber Association, Vol. 51, No. 11, 1978, pages 842-852 SN compound as a slow-acting vulcanizing agent (part 2), Journal of the Japan Rubber Association, Vol. 51, No. 12, 1978, pp. 905-910 S—N compound as a slow-acting vulcanizing agent (Part 3), Journal of the Japan Rubber Association, Vol. 52, No. 1, 1979, pp. 34-40 TRGS552 (N-Nitrosamine) JP-A-8-253463

Problems to be solved by the invention

  It was an object to provide a slow-acting vulcanization accelerator for sulfur and a sulfur-donating vulcanizing agent that would not be a source of harmful nitrosamines.

Means for solving the problem

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is, it succeeds in the synthesis of 2- (dibenzylaminodithio) benzothiazole represented by Chemical Formula 1, and functions as a slow-acting vulcanization accelerator for rubber and a sulfur-donating vulcanizing agent that does not become a source of harmful nitrosamines. It was confirmed.

The invention's effect

  2- (Dibenzylaminodithio) benzothiasol represented by Chemical Formula 1 is useful as a slow-acting vulcanization accelerator for rubber and a sulfur-donating vulcanizing agent that does not generate harmful nitrosamines.

Hereinafter, the present invention will be described in more detail with reference to specific embodiments. However, the present invention is not limited to the examples.

Synthesis example of 2- (dibenzylaminodithio) benzothiazole 3-L four-necked flask was charged with 120.0 g (0.33 mol) of 2- (dibenzylaminothio) benzothiazole (DBzZ) and 11.1 g (0.35 mol) of sulfur. , 130.6 g (0.66 mol) of N, N-dibenzylamine and 1200 ml of methanol were charged and the temperature was raised to 65 ° C. over 30 minutes. After stirring for 15 hours, the mixture was cooled to room temperature to precipitate crystals. After filtration, the crystals were washed twice with 80 ml of methanol to obtain crude crystals. The crude crystals were heated and washed with 1200 ml of methanol at 65 ° C. for 30 minutes, cooled to 2 ° C. and filtered. The obtained crystals were washed with 80 ml of methanol and vacuum-dried at 25 ° C. to obtain 87.9 g of 2- (dibenzylaminodithio) benzothiazole (DBzZ-SS) as an off-white crystalline powder (yield 68%).
m / z 394 (M ⁺ )
IR (KBr) 3029, 2838, 1493, 1454, 1418, 1365, 1310, 1095, 1029, 998, 946, 905, 753, 721, 698, 613, 499, 453 cm ⁻¹

As a comparative substance, N, N-dibenzylbenzothiazole sulfenamide represented by Chemical Formula 2 was used.

Synthesis example of N, N-dibenzylbenzothiazole sulfenamide 3 L 4-necked flask was charged with 200 g (0.60 mol) of 2-benzothiazolyl disulfide and 2400 g of toluene until the internal temperature reached 110 ° C. Azeotropic dehydration was carried out (distilled portion 198.6 g). After cooling to room temperature, 44.8 g (0.63 mol) of chlorine gas was blown in over 1.25 hours. After stirring for 1 hour, the mixture was cooled to 2 ° C. and 475.0 g (2.40 mol) of N, N-dibenzylamine was added dropwise over 1.5 hours. After warming to room temperature and stirring for 15 hours, the precipitated salt was filtered and washed with 800 ml of toluene. The filtrate and washing solution were combined, washed and separated with a 1.8 w% aqueous sodium hydroxide solution, and further washed twice with 500 ml of distilled water. The toluene layer was concentrated at 45 ° C., 10 times the amount of methanol as the crude product was added, and recrystallization was performed. 0.8 g was obtained (yield 36%).
m / z 362 (M ⁺ )
IR (KBr) 2919, 1631, 1493, 1466, 1453, 1428, 1240, 1078, 1026, 910, 754, 729, 700, 607, 459, 425, 408 cm ⁻¹

Rubber test results Table 1 shows the rubber test results of the substance of the present invention and the comparative substance. Each rubber compounding was kneaded by an ordinary method using a closed mixer and an open roll, and a vulcanized rubber for a test was obtained under a predetermined condition using a vulcanizing press. The Mooney scorch test was conducted according to JIS K6300. The vulcanization test using the vibration vulcanization tester was conducted by Alpha Technologies Co., Ltd. D. R. Measured using 2000. Vulcanized rubber physical properties tests were conducted in accordance with JIS K6251 and JIS K6253, respectively.

  From the rubber test results shown in Table 1, the Example substance represented by Chemical Formula 1 in the present invention has the same scorch stability (t5) and the equivalent vulcanization rate (tc ( 90)) and was shown to function as a slow-acting vulcanization accelerator for rubber. In addition, since the example materials have higher vulcanization torque (MH), vulcanized rubber hardness (Hs), and vulcanized rubber tensile properties than the comparative example materials, they also function as sulfur-donating vulcanizing agents. It has been shown.

Claims (3)

2- (dibenzylaminodithio) benzothiazole represented by the formula 1.

  A rubber vulcanization accelerator and / or a rubber vulcanizer comprising as a main component the compound represented by Chemical Formula 1 according to claim 1.   A rubber composition comprising 0.1 to 5.0 parts by weight of the compound represented by Chemical Formula 1 according to claim 1 with respect to 100 parts by weight of rubber.