Mixture of N-(1,3-benzothiazol-2-ylsulfanyl)-2-methyl-cyclohexanamine and N-(1,3-benzothiazol-2-ylsulfanyl)-4-methyl-cyclohexanamine

Abstract

A composition comprising compound (I) of formula and compound (II) of formula wherein R.sup.2a and R.sup.2b independently from each other are a linear alkyl group with 1 to 4 carbon atoms and R.sup.1a, R.sup.1b, R.sup.3a to R.sup.6a and R.sup.3b to R.sup.6b independently from each other are a hydrogen atom or a linear alkyl group with 1 to 4 carbon atoms. ##STR00001##

Claims

1. A composition, comprising: compound (I) of formula: ##STR00009## and a compound (II) of formula: ##STR00010## wherein R.sup.2a and R.sup.2b independently from each other are a linear alkyl group with 1 to 4 carbon atoms and R.sup.1a, R.sup.1b, R.sup.3a to R.sup.6a and R.sup.3b to R.sup.6b independently from each other are a hydrogen atom or a linear alkyl group with 1 to 4 carbon atoms wherein a weight ratio of the compound (I) to the compound (II) is from 1:10 to 10:1.

2. The composition according claim 1, wherein both R.sup.2a and R.sup.2b are a methyl group.

3. The composition according to claim 1, wherein R.sup.1a, R.sup.1b, R.sup.3a to R.sup.6a and R.sup.3b to R.sup.6b are a hydrogen atom.

4. The composition according to any of claim 1, wherein a weight ratio of the compound (I) to the compound (II) is from 1:3 to 3:1.

5. The composition according to claim 1, comprising: at least 50% by weight of the compounds (I) and (II).

6. A method for accelerating vulcanization, the method comprising: accelerating vulcanization with the composition according to claim 1 as a vulcanization accelerator.

7. A rubber composition, comprising: the composition according to claim 1.

Description

EXAMPLES

(1) Products Used in the Examples

(2) N-(1,3-benzothiazol-2-ylsulfanyl)-2-methyl-cyclohexanamine and N-(1,3-benzothiazol-2-ylsulfanyl)-4-methyl-cyclohexanamine in a weight ratio of about 60:40, shortly referred to as Accelerator 1

(3) For comparison: N-(1,3-benzothiazol-2-ylsulfanyl)cyclohexanamine which is solid at 20 C. (1 bar), shortly referred to as CBS

(4) Neorub is a natural 1,4 polyisopren rubber.

(5) Sulfur is elementary sulfur having S8 modification.

Example 1Preparation of Accelarator I

(6) A mixture of ortho-cyclohexylamine and para-cyclohexylamine (25.1 g, about 60% ortho and 40% para) was added to sodium mercaptobenzothiazole (20 wt.-%, 30 g) and the solution (pH=12.3) was heated to 40 C. H.sub.2SO.sub.4 (20 wt. %, 34.8 g) was added over 30 minutes to sink the pH till 10.6. H.sub.2O.sub.2 (10 wt.-%, 52.3 g) was then added over 30 minutes followed by the addition of NaOCl (14 wt.-%, 28.7 g) over 30 minutes. NaOH conc. (5.8 g) was finally added to higher the pH of the solution to 11.6. The phases were separated and the organic one diluted with CH.sub.2Cl.sub.2 and washed with water. The crude residue was filtered through silica gel leaving a yellow oil after solvent removal (17.6 g).

Example 2Suitability of Accelerator I for Rubber

(7) In order to test the potency Accelerator I in comparison to the known standard accelerator CBS as a vulcanization accelerator a standard rubber compound based on natural rubber was manufactured according to DIN 53 670 part 2 (Testing of rubber and elastomers; testing of rubber in standard test mixes; natural rubber (NR)).

(8) In a first step a base compound without any accelerator has been prepared on a roller mill by mixing procedure according to DIN 53 670 as listed in table 1.

(9) TABLE-US-00001 TABLE 1 composition of base compound phr gram Neorub 100 1500 Carbon Black 30 450 ZnO 5 75 Stearic Acid 2 30 Sulfur 2.3 34.5 Total 139.3 2090

(10) The base compound has been divided in three parts:

(11) Test system A without vulcanization accelerator

(12) Test system B with accelerator CBS

(13) Test system C with Accelerator I.

(14) To each test system the accelerators and further additives as listed in table 2 were added. The preparation of the test systems has been carried out according to DIN 53 670 part 2.

(15) TABLE-US-00002 TABLE 2 A B C phr gram phr gram phr gram Base compound 139.3 696.5 139.3 696.5 139.3 696.5 Carbon Black 5 25 5 25 5 25 CBS 0.7 3.5 Accelerator 1 0.7 3.5 Total 144.3 721.5 145 725 145 725
Vulcanization Tests

(16) All compounds have been tested in a rotorless vulcameter (MDR 2000) according to DIN 53 529 part 3 at temperatures of 140 C. and 160 C.

(17) Vulcanization occurs in the vulcameter. An increase of viscosity and torsional moment is observed with proceeding crosslinking. Results are shown in Figure A and Figure B. A high torsional moment corresponds to a high fraction of crosslinked rubber.

(18) Figure A shows the increase of the torsional moment (Nm) over time (minutes) at 140 C.

(19) Figure B shows the increase of the torsional moment (Nm) over time (minutes) at 160 C.