Polysulfide mixtures, method for the production thereof, and use of the polysulfide mixtures in rubber mixtures

Abstract

The present invention relates to novel polysulfides mixtures comprising compounds of the formula (I) ##STR00001##
where n is from 2 to 6, and R is C.sub.1-C.sub.8-alkyl, to processes for the production of said polysulfides mixtures, to use of these for the production of rubber matures, and to rubber vulcanizates produced therefrom.

Claims

1. A polysulfide mixture comprising two or more compounds of the formula (I), ##STR00011## where each R is a C.sub.2-alkylene; each of the two moieties R is identical or different, and is methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, tert-butyl, or C.sub.5-C.sub.8 alkyl; and for at least one of the two or more compounds, n is 4, and for others of the two or more compounds, n is 2, 3, 5 or 6, wherein: the polysulfide mixture comprises a first proportion (x mol %) of the compounds of the formula (I) where n=4, and a second proportion (y mol %)of the compounds of the formula (I) where n is 2,3,5, or 6, and, based on a 100 mol % total quantity of the compounds of the formula (I)
80 mol %(x)[100 mol %(y)].

2. The polysulfide mixture as claimed in claim 1, wherein, for others of the two or more compounds of the formula (I), n is 3, and a proportion of the compounds of the formula (I) where n=3 is less than 10 mol %, of the total quantity of polysulfide compounds of the formula (I).

3. The polysulfide mixture as claimed in claim 1, wherein, for others of the two or more compounds of the formula (I), n is 5, and a proportion of the compounds of the formula (I) where n=5 is less than 10 mol % of the total quantity of polysulfide compounds of the formula (I).

4. The polysulfide mixture as claimed in claim 1, wherein the mixture contains compounds that do not correspond to the formula (I), and a proportion of the compounds which do not correspond to the formula (I) is less than 10 mol %.

5. The polysulfide mixture as claimed in claim 1, wherein each R is methyl.

6. A process for the production of the polysulfide mixture as claimed in claim 1, the process comprising: contacting alkyl 3-mercaptooropionate and S.sub.2Cl.sub.2 in an inert medium, wherein, alkyl is methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, tert-butyl, or C.sub.5-C.sub.8 alkyl.

7. The process as claimed in claim 6, wherein: the inert medium is a first initial amount of the compounds of the formula (I) and the process comprises contacting the alkyl 3-mercaptopropionate and the S.sub.2Cl.sub.2 in the inert medium of compounds of the formula (I) to produce a resultant mixture of the first initial amount of compounds of the formula (I) plus an additional amount of reaction products of the compounds of the formula (I); the contacting of the alkyl 3-mercaptopropionate and the S.sub.2Cl.sub.2 in the inert medium takes place at temperatures of 0 C. to 60 C.; and since the inert medium comprises compounds of the formula (I) and the resultant reaction product are compounds of the formula(I) an additional separtion step of separating the resultant products from the inert medium is not required.

8. The process as claimed in claim 6, wherein HCI gas is produced as a reaction byproduct during the contacting and the method further comprises removing all or some of the resultant HCI gas from the mixture during the reaction via passage of inert gas and/or via application of vacuum.

9. A rubber mixture comprising: at least one rubber, and the polysulfide mixture as claimed in claim 1.

10. The rubber mixture as claimed in claim 9, further comprising: at least one sulfur-containing alkoxysiane, and at least one silica-based filler.

11. The rubber mixture as claimed in claim 9, further comprising at least one crosslinking agent.

12. The rubber mixture as claimed in claim 9, wherein the at least one rubber comprises at least one SBR rubber and at least one BR rubber, in a ratio by weight of SBR rubber to BR rubber of 60:40 to 90:10.

13. The rubber mixture as claimed in claim 12, further comprising at least one NR rubber, in a ratio by weight of SBR rubber to BR rubber to NR rubber of from 60 to 85:10 to 35:5 to 20.

14. A process for the production of the rubber mixture as claimed in claim 9, the process comprising mixing the at least one rubber and the polysulfide mixture as claimed in claim 1.

15. A process for the production of vulcanizates, the process comprising vulcanizing the rubber mixture as claimed in claim 9 at a temperature of 100 to 200 C.

16. A vulcanizate obtained via vulcanization of the rubber mixture as claimed in claim 9.

17. A rubber product comprising the vulcanizate as claimed in claim 16.

18. A vehicle comprising the rubber product as claimed in claim 17.

19. An additive composition comprising at least one sulfur-containing alkoxysilane and a polysuifide mixture as claimed in claim 1.

20. A method for producing the additive composition as claimed in claim 19, the method comprising combining the polysulfide mixture as claimed in claim 1 with the at least one sulfur-containing alkoxysilane.

21. A process for reducing the roving resistance of tires, the process comprising mixing the polysulfide mixture as claimed in claim 1 with a non-crosslinked or partially crosslinked rubber mixture, forming at least parts of the tire from the rubber mixture, and vulcanizing the mixture.

22. The polysulfide mixture as claimed in claim 1, wherein: a proportion of compounds where n=4 is at least 85%; for another of the two or more compounds of the formula (I), n is 4, and a proportion of the compounds of the formula (I) where n=3 is less than 6% based on the total quantity of polysulfide compounds of the formula (I); and for another of the two or more compounds of the formula (I), n is 5, and a proportion of the compounds of the formula (I) where n=5 is less than 6% based on the total quantity of polysulfide compounds of the formula (I); and the mixture contains compounds that do not correspond to the formula (I) and a proportion of compounds which do not correspond to the formula (I) is less than 3%.

23. The polysulfide mixture as claimed in claim 1, wherein: each R is methyl, ethyl, n-propyl, n-butyl, or isooctyl, a proportion of compounds where n=4 is at least 90%; for another of the two or more compounds of the formula (I), n is 3, and a proportion of the compounds of the formula (I) where n=3 is less than 4% based on the total quantity of polysulfide compounds of the formula (I); and for another of the two or more compounds of the formula (I), n is 5, and a proportion of the compounds of the formula (I) where n=5 is less than 4% based on the total quantity of polysulfide compounds of the formula (I); the mixture contains compounds that do not correspond to the formula (I) and a proportion of compounds which do not correspond to the formula (I) is less than 1%.

24. The polysulficie mixture as claimed in claim 1, wherein: each R is methyl; a proportion of compounds where n=4 is 95-99 mol %; for another of the two or more compounds of the formula (I), n is 3, and a proportion of the compounds of the formula (I) where n=3 is less than 2 mol % based on the total quantity of polysulfide compounds of the formula (I); and for another of the two or more compounds of the formula (I), n is 5, and a proportion of the compounds of the formula (I) where n=5 is less than 3 mol % based on the total quantity of polysulfide compounds of the formula (I); and the mixture contains compounds that do not correspond to the formula (I) and a proportion of compounds which do not correspond to the formula (I) is less than 0.2 mol % of compound of the polysulfide mixture.

25. The process as claimed in claim 6, wherein: the contacting of the alkyl 3-mercaptopropionate and the S.sub.2Cl.sub.2 is carried out at a temperature of 10 C. to 45 C. to form the compounds of the formula (I)in inert medium; and the process comprises removing the inert medium from the compounds of the formula (I) at a temperature no higher than 40 C.

26. The process as claimed in claim 6, wherein: the contacting of the alkyl 3-mercaptopropionate and S.sub.2Cl.sub.2 is carried out at a temperature of 15 C. to 35 C. to form the compounds of the formula (I) in inert medium; and the process comprises removing the inert medium from the compound of the formula (I) at temperature higher than 35 C.

27. The process as claimed in claim 6, wherein: the contacting of the alkyl 3-mercaptopropionate and S.sub.2Cl.sub.2 is carried out at a temperature of 20C. to 30C. to form the compound of the formula(I) in inert medium; the process comprises removing the inert medium from the compound of the formula (I)at a temperature no higher than 30 C.; and the alkyl 3-mercaptopropionate is methyl 3-mercaptopropionate.

28. The process for the production of vulcanizates as claimed in claim 15, wherein the temperature is 130 to 180 C.

29. The additive composition as claimed in claim 19, wherein the at least one sulfur-containing alkoxysilahe is selected from the group consisting of bis(triethoxysilyipropyl) tetrasulfane, bis(triethoxysilylpropyl) disulfane, 3-(triethoxysilyl)-1-propanethiol, polyether-functionalized meroaptosilane, and thioester-functionalized alkoxysilane.

Description

EXAMPLE 1

(1) ##STR00005##

(2) Apparatus: 500 ml four-necked flask with thermometer, dropping funnel with pressure equalizer, reflux condenser with gas outlet attachment (bubble counter), and hose, stirrer, gas inlet tube

(3) Initial charge: 92 g (0.75 mol) of methyl 3-mercaptopropionate (Acros, 98%) 250 ml of cyclohexane (p.A., Merck dried over molecular sieve)

(4) Feed: 51.2 g (0.375 mol) of disulfur dichloride (99%, from Merck)

(5) Dry cyclohexane and methyl 3-mercaptopropionate were used as initial charge in the nitrogen-purged apparatus. Once the methyl 3-mercaptopropionate had dissolved completely, the disulfur dichloride was added dropwise within about 1 h at a temperature of from 5-10 C. while nitrogen was passed through the system. Adjustment of metering rate was such that a temperature of 10 C. was not exceeded. Once the reaction had ended, stirring of the mixture was continued overnight at room temperature while nitrogen was passed through the system. The reaction solution was then concentrated at 50 C. on a rotary evaporator, and drying was continued at 60 C. in a vacuum drying oven to constant weight.

(6) Yield: 108.4 g (95.6%) of a polysulfide mixture of the idealized formula

(7) ##STR00006##

(8) Elemental Analysis:

(9) C:31.9% H:5.3% O:21.7% S: 42.0%

(10) The product was analyzed by RP-HPLC and time-of-flight mass spectrometry (TOF MS).

(11) The percentage data for the compounds of the formula (I) are derived from the HPLC area percentages, using RI detector.

(12) <1% of compound (II), 16% of compound (III), 65% of compound (IV), 15% of compound (V), 4% of compound (VI)

EXAMPLE 2

(13) ##STR00007##

(14) Apparatus: 500 ml four-necked flask with thermometer, dropping funnel with pressure equalizer, reflux condenser with gas outlet attachment (bubble counter), and hose, stirrer, gas inlet tube

(15) Initial charge: 92 g (0.75 mol) of methyl 3-mercaptopropionate (Acros, 98%) 250 ml of cyclohexane (p.A., Merck dried over molecular sieve)

(16) Feed: 51.2 g (0.375 mol) of disulfur dichloride (99%, from Merck)

(17) Dry cyclohexane and methyl 3-mercaptopropionate were used as initial charge in the nitrogen-purged apparatus. Once the methyl 3-mercaptopropionate had dissolved completely, the disulfur dichloride was added dropwise within about 30 min at a temperature of from 20-25 C. while nitrogen was passed through the system. Adjustment of metering rate was such that a temperature of 25 C. was not exceeded. Once the reaction had ended, stirring of the mixture continued overnight at room temperature while nitrogen was passed through the system. The reaction solution was then concentrated at 30 C. on a rotary evaporator.

(18) Yield: 115 g (101.4%) of a polysulfide mixture of the idealized formula

(19) ##STR00008##

(20) The quantities used of the starting materials are based on the minimum content guaranteed by the manufacturer, e.g. 98%. Because actual purities of the starting materials were higher, and because of inaccuracies due to rounding, the calculated yield was slightly above 100%.

(21) Elemental analysis:

(22) C:31.9% H:4.5% O:21.7% S:42.1% Cl:<10 ppm

(23) The product was analyzed by RP-HPLC and time-of-flight mass spectrometry (TOF MS).

(24) The percentage data for the compounds of the formula (I) are derived from the HPLC area percentages, using RI detector.

(25) <1% of compound (II), 1% of compound (III), 96% of compound (IV), 2% of compound (V), <1 % of compound (VI)

EXAMPLE 3

(26) ##STR00009##

(27) Apparatus: 500 ml four-necked flask with thermometer, dropping funnel with pressure equalizer, reflux condenser with gas outlet attachment (bubble counter), and hose, stirrer, gas inlet tube

(28) Initial charge; 92 g (0.75 mol) of methyl 3-mercaptopropionate (Acros, 98%) 200 g of polysulfide mixture produced by analogy with Example 2

(29) Feed: 51.2 g (0.375 mol) of disulfur dichloride (99%, from Merck)

(30) The polysulfide mixture (produced by analogy with Example 2) and methyl 3-mercaptopropionate were used as initial charge in the nitrogen-purged apparatus. Once the methyl 3-mercaptopropionate had dissolved completely, the disulfur dichloride was added dropwise within about 30 min at a temperature of from 20-25 C. while nitrogen was passed through the system. Adjustment of metering rate was such that a temperature of 25 C. was not exceeded. Once the reaction had ended, stirring of the mixture was continued overnight at room temperature while nitrogen was passed through the system. Treatment of the reaction solution then continued on a rotary evaporator at about 30 C. for 2 h.

(31) Yield: 200 g+115 g (101.4%) of a polysulfide mixture of the idealized formula

(32) ##STR00010##

(33) Elemental analysis:

(34) C:32.0% H:4.8% O:21.8% S:41.9% Cl:<10 ppm

(35) The product was analyzed by RP-HPLC. The percentage data for the compounds of the formula (I) are derived from the HPLC area percentages, using RI detector.

(36) <1% of compound (II), 1% of compound (III), 96% of compound (IV), 2% of compound (V), <1% of compound (VI)

(37) HPLC system with vacuum degasser, pump, column oven, injection system, and RI detector.

(38) Column type: Eclipse XDB-C8, 5 m

(39) Column length: 150 mm

(40) Internal column diameter: 4.6 mm

(41) Mobile phase: 33% of water, 67% of methanol

(42) Column temperature: 35 C.

(43) Flow rate: 0.8 ml/min

(44) Elution time: 30 min

(45) Injection volume: 2 l

(46) RI detector: Agilent 1100 series G1362A

(47) 10 ml of tetrahydrofuran were used as initial charge in a 25 ml beaded-rim bottle, and about 300 l of the sample were added, the mixture was homogenized, and chromatography of the solution then followed directly. Evaluation gives the area percentages.

(48) Production of Rubber Mixtures and of Rubber Vulcanizates

(49) The rubber formulations listed in table 1 were respectively mixed in accordance with multistage processes described below.

(50) 1st mixing stage: BUNA CB 24 and BUNA VSL 5025-2 were used as initial charge in an internal mixer and mixed for about 30 seconds addition of two thirds of VULKASIL S, two thirds of SI 69, and two thirds of the total quantity of polysulfide mixture of the invention, and mixing for about 60 seconds addition of one third of VULKASIL S, one third of SI 69, and one third of the total quantity of polysulfide mixture of the invention, and TUDALEN 1849-1, and mixing for about 60 seconds
addition of CORAX N 339, EDENOR C 18 98-100, VULKANOX 4020/LG, VULKANOX HS/LG, ROTSIEGEL ZINC WHITE, and also ANTILUX 654, and mixing for about 60 seconds. The mixing temperature was 150 C.

(51) 2nd mixing stage:

(52) After conclusion of the first mixing stage, the mixture was passed to a downstream roll mill, shaped to give a sheet, and stored for 24 hours at room temperature. The processing temperatures here were below 60 C.

(53) 3rd mixing stage:

(54) The third mixing stage involved further mastication at 150 C. in a kneader.

(55) 4th mixing stage:

(56) Addition of the additional substances CHANCEL 90/95 GROUND SULFUR, VULKACIT CZ/C, VULKACIT D/C on a roll at temperatures below 80 C.

(57) The rubber mixtures were then fully vulcanized at 170 C. Table 2 gives the properties of the rubber preparations produced and of vulcanizates of these.

(58) TABLE-US-00002 TABLE 1 Rubber formulation Rubber Rubber Rubber formula- formula- formula- Reference tion 1 tion 2 tion 3 BUNA CB 24 30 30 30 30 BUNA VSL 5025-5 96 96 96 96 CORAX N 339 6.4 6.4 6.4 6.4 VULKASIL S 80 80 80 80 TUDALEN 1849-1 8 8 8 8 EDENOR C 18 98-100 1 1 1 1 VULKANOX 4020/LG 1 1 1 1 VULKANOX HS/LG 1 1 1 1 ROTSIEGEL ZINC 2.5 2.5 2.5 2.5 WHITE ANTILUX 654 1.5 1.5 1.5 1.5 SI 69 6.4 6.4 6.4 6.4 VULKACIT D/C 2 2 2 2 VULKACIT CZ/C 1.5 1.5 1.5 1.5 CHANCEL 90/95 1.5 1.5 1.5 1.5 GROUND SULFUR Compound 1 1 Compound 2 1 Compound 3 1

(59) Quantitative Data in Phr (Parts by Weight Per 100 Parts of Rubber)

(60) TABLE-US-00003 Producer/ Trade name Description Marketed by BUNA CB 24 BR Lanxess Deutschland GmbH BUNA VSL SBR Lanxess 5025-2 Deutschland GmbH CORAX N 339 Carbon black Degussa-Evonik GmbH VULKASIL S Silica Lanxess Deutschland GmbH TUDALEN Mineral oil Hansen&Rosenthal 1849-1 KG EDENOR C Stearic acid Cognis 18 98-100 Deutschland GmbH VULKANOX N-1,3-Dimethylbutyl-N-phenyl-p- Lanxess 4020/LG phenylenediamine Deutschland GmbH VULKANOX Polymerized 2,2,4-trimethyl-1,2- Lanxess HS/LG dihydroquinoline Deutschland GmbH ROTSIEGEL Zinc oxide Grillo ZINC WHITE Zinkoxid GmbH ANTILUX 654 Light-stabilizer wax RheinChemie Rheinau GmbH SI 69 Bis(triethoxysilylpropyl) Evonik tetrasulfide Industries VULKACIT 1,3-Diphenylguanidine Lanxess D/C Deutschland GmbH VULKACIT N-Cyclohexyl-2- Lanxess CZ/C benzothiazolesulfenamide Deutschland GmbH CHANCEL Sulfur Solvay 90/95 Deutschland GROUND GmbH SULFUR

(61) TABLE-US-00004 TABLE 2 Summary of results Rubber Rubber formulation formulation Parameter Unit DIN Reference 1 2 Mooney viscosity (ML 1 + 4) [MU] 53523 95 82 87 Mooney scorch for 130 C. (t5) Sec ASTM 1253 1244 884 D5289-95 Full vulcanization for 170 C./ Sec 53529 1417 1617 1648 t95 Shore A hardness at 23 C. [Shore A] 53505 66 72 69 300 modulus MPa 53504 15 17 14 Elongation at break % 53504 349 346 350 Tensile strength MPa 53504 19 20 17 Abrasion mm 53516 74 95 73 Rolling resistance (tan 0.133 0.168 0.107 (60 C.))