PROCESS FOR PREPARING POLYSULFANE SILANES BY MEANS OF PHASE TRANSFER CATALYSIS

Abstract

A process for preparing polysulfane silanes of formula (I):

(R.sup.1).sub.3-mR.sup.2.sub.mSi—R.sup.3—S.sub.x—R.sup.3—SiR.sup.2.sub.m(OR.sup.1).sub.3-m  (I),

may include reacting at least one halosilane of formula (II):

(R.sup.1).sub.3-mR.sup.2.sub.mSi—R.sup.3-Hal  (II),

with M(SH).sub.y and/or M.sub.zS and sulfur, in the presence of a phase transfer catalyst, a base and an aqueous phase, wherein the phase transfer catalyst is an alkylguanidinium catalyst of the formula (III):

##STR00001##

and at least two groups of R.sup.4, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 are —(CH.sub.2).sub.2CH.sub.3, —CH.sub.2CH.sub.3, or —CH.sub.3.

Claims

1. A process for preparing one or more polysulfane silanes formula (I)
(R.sup.1).sub.3-mR.sup.2.sub.mSi—R.sup.3—S.sub.x—R.sup.3—SiR.sup.2.sub.m(OR.sup.1).sub.3-m  (I) the process comprising: reacting at least one halosilane of formula (II):
(R.sup.1).sub.3-mR.sup.2.sub.mSi—R.sup.3-Hal  (II), with M(SH).sub.y and/or M.sub.zS and sulfur, in the presence of a phase transfer catalyst, a base, and an aqueous phase, wherein R.sup.1 are independently a C.sub.1-C.sub.10-alkoxy group, phenoxy group, or (R′—O).sub.rR″ where R′ is independently a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C.sub.1-C.sub.30 hydrocarbon group, r is an integer in a range of from 1 to 30, and R″ is unsubstituted or substituted, branched or unbranched, monovalent alkyl, alkenyl, aryl, or aralkyl group, R.sup.2 are independently C.sub.6-C.sub.20 aryl, C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.20 alkenyl, C.sub.7-C.sub.20 aralkyl, or halogen, R.sup.3 are independently a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C.sub.1-C.sub.30 hydrocarbon group, m is the same or different and are 0, 1, 2 or 3, x is 2-10, Hal is Cl, Br, or I y is 1 or 2, and M is Na or K when y is 1, and M is Ca or Mg when y is 2, z is 1 or 2, and M is Ca or Mg when z is 1, and M is Na or K when z is 2, and wherein the phase transfer catalyst is an alkylguanidinium catalyst of formula (III) ##STR00003## wherein Y is an element of main group 5, R.sup.4, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 are independently —(CH.sub.2).sub.kCH.sub.3 alkyl radicals, where k is in a range of from 0 to 9, or one or two ring closures —(CH.sub.2).sub.p—, where p is in a range of from 1 to 5, is present between different substituents, R.sup.9 is an n-valent substituted, saturated or unsaturated, branched or unbranched hydrocarbon group, and at least two groups of R.sup.4, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 are —(CH.sub.2).sub.2CH.sub.3, —CH.sub.2CH.sub.3, or —CH.sub.3, n is 1, 2, 3, or 4, and X.sup.− is Cl.sup.−, F.sup.−, I.sup.−, Br.sup.−, ClO.sub.4.sup.−, PF.sub.6.sup.−, BF.sub.4.sup.−, (C.sub.6H.sub.5).sub.4B.sup.−, H.sub.2PO.sub.4.sup.−, CH.sub.3SO.sub.3.sup.−, C.sub.6H.sub.5SO.sub.3.sup.−, HSO.sub.4.sup.−, NO.sub.3.sup.−, or (SO.sub.4.sup.2−).sub.1/2.

2. The process of claim 1, wherein R.sup.1 is ethoxy, m is 0, R.sup.3 is (CH.sub.2).sub.3, M is Na, and Hal Hal is Cl.

3. The process of claim 1, wherein Y is N.

4. The process of claim 1, wherein n is 1, and at least two groups of R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8 and R.sup.9 are —(CH.sub.2).sub.2CH.sub.3, —CH.sub.2CH.sub.3, or —CH.sub.3.

5. The process of claim 4, wherein at least four groups of R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8 and R.sup.9 are —CH.sub.2CH.sub.3 or —CH.sub.3.

6. The process of claim 4, wherein the alkylguanidinium catalyst of the formula (III) is hexaethylguanidinium chloride, hexapropylguanidinium chloride, dimethyltetrabutylguanidinium chloride, tetramethyldibutylguanidinium chloride, diethyltetrabutylguanidinium chloride, tetrabutyldipropylguanidinium chloride, dibutyltetrapropylguanidinium chloride, diethyltetrapropylguanidinium chloride, tetraethyldipropylguanidinium chloride, tetraethyldibutylguanidinium chloride, tetraethyldipentylguanidinium chloride, tetramethyldipentylguanidinium chloride, dipentyltetrapropylguanidinium chloride tetraethyldihexylguanidinium chloride, or dihexyltetramethylguanidinium chloride.

7. The process of claim 5, wherein the alkylguanidinium catalyst of the formula (III) is hexaethylguanidinium chloride, tetraethyldihexylguanidinium chloride, tetraethyldipentylguanidinium chloride, or dibutyltetraethylguanidinium chloride.

8. The process of claim 1, wherein the base is M.sub.3-wCO.sub.3, M(OH).sub.w, M.sub.3-w(HPO.sub.4), M(H.sub.2PO.sub.4).sub.w, or M.sub.3(PO.sub.4).sub.w, wherein w is 1 or 2, and M is Na or K when w is 1, and M is Ca or Mg when w is 2.

9. The process of claim 8, wherein the base is Na.sub.2CO.sub.3.

10. The process of claim 1, wherein the reacting is conducted at a temperature in a range of from 60° C. to 110° C.

11. The process of claim 4, wherein the alkylguanidinium catalyst of the formula (III) is hexaethylguanidinium chloride, hexapropylguanidinium chloride, dimethyltetrabutylguanidinium chloride, tetramethyldibutylguanidinium chloride, diethyltetrabutylguanidinium chloride, tetrabutyldipropylguanidinium chloride, dibutyltetrapropylguanidinium chloride, diethyltetrapropylguanidinium chloride, tetraethyldipropylguanidinium chloride, tetraethyldibutylguanidinium chloride, tetraethyldipentylguanidinium chloride, tetramethyldipentylguanidinium chloride, dipentyltetrapropylguanidinium chloride tetraethyldihexylguanidinium chloride, or dihexyltetramethylguanidinium chloride, and wherein the base is M.sub.3-wCO.sub.3, M(OH).sub.w, M.sub.3-w(HPO.sub.4), M(H.sub.2PO.sub.4).sub.w, or M.sub.3(PO.sub.4).sub.w, W being 1 or 2, with M being Na or K when w is 1, and M being Ca or Mg when w is 2.

12. The process of claim 5, wherein the alkylguanidinium catalyst comprises hexaethylguanidinium chloride.

13. The process of claim 5, wherein the alkylguanidinium catalyst comprises tetraethyldihexylguanidinium chloride.

14. The process of claim 5, wherein the alkylguanidinium catalyst comprises tetraethyldipentylguanidinium chloride.

15. The process of claim 5, wherein the alkylguanidinium catalyst comprises dibutyltetraethylguanidinium chloride.

16. The process of claim 8, wherein the base is NaOH.

17. The process of claim 2, wherein the base is Na.sub.2CO.sub.3 or NaOH.

18. The process of claim 6, wherein the base is Na.sub.2CO.sub.3 or NaOH.

Description

EXAMPLES

Comparative Example 1: Bis(Triethoxysilylpropyl)Tetrasulfane Using Tetra-n-Butylammonium Bromide (from EP 19217272.4 Comparative Example 2)

[0145] For preparation of bis(triethoxysilylpropyl)tetrasulfane by means of phase transfer catalysis, a mixture of sodium hydroxide (81 g, 1.0 mol, 1.0 equiv.), sodium hydrogensulfide (284 g, 2.0 mol, 2.0 equiv., 40.0% aqueous solution) and water (158 g, 8.8 mol, 4.2 equiv.) was heated to 70° C. The reaction mixture was first stirred at 70° C. for 10 min, then sulfur (184 g, 5.7 mol, 2.8 equiv.) was added to the mixture, which was stirred at 72° C. for a further 15 minutes. Tetra-n-butylammonium bromide (17 g, 0.03 mol, 0.01 equiv., 50% aqueous solution) and (3-chloropropyl)triethoxysilane (999 g, 4.2 mol, 2.0 equiv.) were added successively to the reaction mixture at 70-80° C. The suspension was stirred at 75° C. for 2 hours (GC conversion after 2 hours=98%). After the reaction had ended, water (249 g) was added and the phases were separated at 71° C. The crude product (1.1 kg) was obtained as a yellow liquid. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 10 mbar abs., such that the bis(triethoxysilylpropyl)tetrasulfane was isolated as bottom product and then filtered.

[0146] LC-MS: 50 ppm TBAB (PTC catalyst)

[0147] GC: 0.38% tributylamine (degradation product of the PTC catalyst)

[0148] HPLC: monomer content 93.8%

[0149] Storage stability: HPLC monomer content (3 months): 92.9%

Comparative Example 2: Bis(Triethoxysilylpropyl)Disulfane Using Tetra-n-Butylammonium Bromide (from EP 19217272.4 Comparative Example 1)

[0150] For preparation of bis(triethoxysilylpropyl)disulfane by means of phase transfer catalysis, a mixture of sodium carbonate (189 g, 1.8 mol, 1.2 equiv.), sodium hydrogensulfide (225 g, 1.6 mol, 1.0 equiv., 40.0% aqueous solution) and water (572 g, 32 mol, 21 equiv.) was heated to 72° C. The reaction mixture was first stirred at 72° C. for 10 min, then sulfur (55 g, 1.7 mol, 1.1 equiv.) was added to the mixture, which was stirred at 72° C. for a further 45 minutes. Tetra-n-butylammonium bromide (20 g, 0.03 mol, 0.02 equiv., 50% aqueous solution) and (3-chloropropyl)triethoxysilane (743 g, 3.1 mol, 2.0 equiv.) were added successively to the reaction mixture at 70-80° C. The suspension was stirred at 75° C. for 3 hours (GC conversion after 1 hour=98%). After the reaction had ended, water (589 g) was added and the phases were separated at 71° C. The crude product (793 g) was obtained as a yellow liquid. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 10 mbar abs., such that the bis(triethoxysilylpropyl)disulfane was isolated as bottom product and then filtered.

[0151] LC-MS: 4 ppm TBAB (PTC catalyst)

[0152] GC: 0.54% tributylamine (degradation product of the PTC catalyst)

[0153] HPLC: monomer content 91.5%

[0154] Storage stability: HPLC monomer content (3 months): 90.7%

Comparative Example 3: Bis(Triethoxysilylpropyl)Disulfane Using Hexabutylguanidinium Chloride

[0155] For preparation of bis(triethoxysilylpropyl)disulfane by means of phase transfer catalysis, a mixture of sodium carbonate (94 g, 0.9 mol, 1.2 equiv.), sodium hydrogensulfide (107.9 g, 0.77 mol, 1.0 equiv., 40.0% aqueous solution) and water (286 g, 15.9 mol, 20.6 equiv.) was heated to 75° C. The reaction mixture was first stirred at 75° C. for 10 min, then sulfur (27.8 g, 0.9 mol, 1.1 equiv.) was added to the mixture, which was stirred at 75° C. for a further 45 minutes. Hexabutylguanidinium chloride (2.8 g, 0.003 mol, 0.004 equiv., 50% aqueous solution) and (3-chloropropyl)triethoxysilane (372 g, 1.5 mol, 2.0 equiv.) were added successively to the reaction mixture at 70-80° C. The suspension was stirred at 75° C. for 3 hours. After the reaction had ended, water (426 g) was added and the phases were separated at 71° C. The crude product (355.32 g) was obtained as a yellow liquid. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 10 mbar abs., such that the bis(triethoxysilylpropyl)disulfane was isolated as bottom product and then filtered.

[0156] LC-MS: 0.2% HBG-Cl (PTC catalyst)

[0157] GC: 0.00% tributylamine

[0158] HPLC: monomer content 89.4%

[0159] Storage stability: HPLC monomer content (3 months): 86.8%

Comparative Example 4: Bis(Triethoxysilylpropyl)Tetrasulfane Using Hexabutylguanidinium Chloride

[0160] For preparation of bis(triethoxysilylpropyl)tetrasulfane by means of phase transfer catalysis, a mixture of sodium hydroxide (21 g, 0.5 mol, 1.0 equiv.), sodium hydrogensulfide (71 g, 0.5 mol, 1.0 equiv., 40.0% aqueous solution) and water (40 g, 2.2 mol, 4.2 equiv.) was heated to 70° C. The reaction mixture was first stirred at 70° C. for 10 min, then sulfur (184 g, 5.7 mol, 2.8 equiv.) was added to the mixture, which was stirred at 72° C. for a further 15 minutes. Hexabutylguanidinium chloride (1.1 g, 0.001 mol, 0.003 equiv., 50% aqueous solution) and (3-chloropropyl)triethoxysilane (250 g, 1.0 mol, 2.0 equiv.) were added successively to the reaction mixture at 70-80° C. The suspension was stirred at 75° C. for 2 hours (GC conversion after 2 hours=98%). After the reaction had ended, water (98 g) was added and the phases were separated at 71° C. The crude product (277.91 g) was obtained as an orange to brown liquid. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 10 mbar abs., such that the bis(triethoxysilylpropyl)tetrasulfane was isolated as bottom product and then filtered.

[0161] LC-MS: 0.2% HBG-Cl (PTC catalyst)

[0162] GC: 0.00% tributylamine

[0163] monomer content 88.1%

[0164] Storage stability: HPLC monomer content (3 months): 82.8%

Example 1: Bis(Triethoxysilylpropyl)Disulfane Using Tetraethyldibutylguanidinium Chloride

[0165] For preparation of bis(triethoxysilylpropyl)disulfane by means of phase transfer catalysis, a mixture of sodium carbonate (94 g, 0.89 mol, 1.15 equiv.), sodium hydrogensulfide (107.9 g, 0.77 mol, 1.0 equiv., 40.0% aqueous solution) and water (286 g, 15.9 mol, 20.6 equiv.) was heated to 75° C. The reaction mixture was first stirred at 75° C. for 10 min, then sulfur (27.7 g, 0.9 mol, 1.12 equiv.) was added to the mixture, which was stirred at 75° C. for a further 45 minutes.

[0166] Tetraethyldibutylguanidinium chloride (4.1 g, 0.006 mol, 0.008 equiv., 50% aqueous solution) and (3-chloropropyl)triethoxysilane (372 g, 1.5 mol, 2.0 equiv.) were added successively to the reaction mixture at 70-80° C. The suspension was stirred at 75° C. for 3 hours. After the reaction had ended, water (450.00 g) was added and the phases were separated at 71° C. The crude product (361.16 g) was obtained as a colourless to pale green liquid. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 10 mbar abs., such that the bis(triethoxysilylpropyl)disulfane was isolated as bottom product and then filtered.

[0167] GC-MS analysis did not show any presence of catalyst degradation products (diethylamine, dibutylamine) in the product.

[0168] 6 ppm TEDBG-Cl (PTC catalyst)

[0169] GC: 0.00% tributylamine

[0170] HPLC: monomer content) 94.7%

[0171] Storage stability: HPLC monomer content (3 months): 94.4%

Example 2: Bis(Triethoxysilylpropyl)Tetrasulfane Using Tetraethyldibutylguanidinium Chloride

[0172] For preparation of bis(triethoxysilylpropyl)tetrasulfane by means of phase transfer catalysis, a mixture of sodium hydroxide (41 g, 1.0 mol, 1.0 equiv.), sodium hydrogensulfide (143 g, 1.01 mol, 0.98 equiv., 40.1% aqueous solution) and water (78 g, 4.4 mol, 4.24 equiv.) was heated to 70° C., then sulfur (94 g, 2.1 mol, 2.82 equiv.) was added to the mixture which was stirred at 70° C. for a further 15 minutes. Tetraethyldibutylguanidinium chloride (3.32 g, 0.005 mol, 0.005 equiv., 50% aqueous solution) and (3-chloropropyl)triethoxysilane (501 g, 2.1 mol, 2.0 equiv.) were added successively to the reaction mixture at 72° C.-78° C. The suspension was stirred at 75° C. for 3 hours. After the reaction had ended, water (122.00 g) was added and the phases were separated at 70° C.

[0173] The crude product (559.68 g) was obtained as a dark brown liquid. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 10 mbar abs., such that the bis(triethoxysilylpropyl)tetrasulfane was isolated as bottom product and then filtered.

[0174] GC-MS analysis did not show any presence of catalyst degradation products (diethylamine, dibutylamine) in the product.

[0175] LC-MS: 190 ppm TEDBG-Cl (PTC catalyst)

[0176] GC: 0.00% tributylamine

[0177] HPLC: monomer content 95.1%

[0178] Storage stability: HPLC monomer content (3 months): 93.9%

Example 3: Bis(Triethoxysilylpropyl)Tetrasulfane Using Hexaethylguanidinium Chloride

[0179] For preparation of bis(triethoxysilylpropyl)tetrasulfane by means of phase transfer catalysis, a mixture of sodium hydroxide (0.730 g, 18.2 mol, 1.0 equiv.), sodium hydrogensulfide (1.003 kg, 17.9 mol, 0.980 equiv., 40.1% aqueous solution) and water (1.394 kg, 77.4 mol, 4.24 equiv.) was heated to 106° C., then sulfur (1.653 kg, 51.6 mol, 2.825 equiv.) was added to the mixture which was stirred at 106° C. for a further 15 minutes. Hexaethylguanidinium chloride (39 g, 0.1 mol, 0.008 equiv., 35% aqueous solution) and (3-chloropropyl)triethoxysilane (8.789 kg, 36.5 mol, 2.0 equiv.) were added successively to the reaction mixture at 106° C.-112° C. The suspension was stirred at 106° C. for 3 hours (GC conversion after 2 hours=98%). After the reaction had ended, water (2.559 kg) was added and the phases were separated at 80° C. The crude product (10.076 kg) was obtained as a yellow liquid. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 10 mbar abs., such that the bis(triethoxysilylpropyl)tetrasulfane was isolated as bottom product and then filtered.

[0180] GC-MS analysis did not show any presence of catalyst degradation products (diethylamine) in the product.

[0181] LC-MS: 30 ppm HEG-Cl

[0182] GC: 0.00% tributylamine

[0183] HPLC: monomer content 92.7%

[0184] Storage stability: HPLC monomer content (3 months): 91.6%

[0185] Table 1 shows all values of comparative examples 1-4 and examples 1-3. Comparative example 1 and 2 using TBAB as catalyst show tributylamine (TBA) in the end product. TBA is classified as hazardous to health. The products prepared using the process according to the invention (examples 1-3) show no tributylamine (TBA) in the end product.

[0186] Comparison of comparative example 3 with example 1 (preparation of bis(triethoxysilylpropyl)disulfane) reveals better storage stability (smaller alteration in the monomer content) for the inventive example.

[0187] Comparison of comparative example 4 with example 2 and 3 (both preparation of bis(triethoxysilylpropyl)tetrasulfane) reveals better storage stability (smaller alteration in the monomer content) for the inventive examples.

TABLE-US-00001 TABLE 1 Monomer Monomer TBA content content content in the Catalyst content Product Catalyst 0 months 3 months product in the product Comparative examples 1 Bis(triethoxysilyl- TBAB 93.8 92.9 0.38% 50 ppm TBAB propyl)tetrasulfane 2 Bis(triethoxysilyl- TBAB 91.5 90.7 0.54% 4 ppm TBAB propyl)disulfane 3 Bis(triethoxysilyl- HBG-Cl 89.4 86.8 0.00% 0.2% HBG-Cl propyl)disulfane 4 Bis(triethoxysilyl- HBG-Cl 88.1 82.8 0.00% 0.2% HBG-Cl propyl)tetrasulfane Examples 1 Bis(triethoxysilyl- TEDBG-Cl 94.7 94.4 0.00% 6 ppm TEDBG-Cl propyl)disulfane 2 Bis(triethoxysilyl- TEDBG-Cl 95.1 93.9 0.00% 190 ppm TEDBG-Cl propyl)tetrasulfane 3 Bis(triethoxysilyl- HEG-Cl 92.7 91.6 0.00% 30 ppm HEG-Cl propyl)tetrasulfane

Example 4: Examination of Rubber Characteristics

[0188] The materials used are listed in Table 2. Test methods used for the mixtures and vulcanizates thereof were effected according to Table 3. The rubber mixtures were produced with a GK 1.5E internal mixer from Harburg Freudenberger Maschinenbau GmbH.

TABLE-US-00002 TABLE 2 List of materials used in the examples S-SBR BUNA ® VSL 4526-2, Ultrapolymers Deutschland GmbH BR BUNA ® CB 24, Ultrapolymers Deutschland GmbH Silica ULTRASIL ® 7000 GR, Evonik Industries AG Carbon black CORAX ® N330, Gustav Grolmann GmbH & Co. KG Silane prepared using HBG-Cl catalyst (comparative example 4 after 3 months' storage) Silane with HEG-Cl catalyst (example 3 after 3 months' storage) ZnO Zinkweiss Rotsiegel, Grillo Zinkoxid GmbH Stearic acid Edenor ST1, Caldic Deutschland GmbH Oil Vivatec 500, Hansen & Rosenthal KG Wax Protektor G 3108, Paramelt B. V. 6PPD Vulkanox ® 4020/LG, Rhein-Chemie GmbH TMQ Vulkanox ® HS/LG, Rhein-Chemie GmbH DPG Rhenogran ® DPG-80, Rhein-Chemie GmbH CBS Vulkacit ® CZ/EG-C, Rhein-Chemie GmbH Sulfur ground sulfur, Azelis S. A. TBzTD Richon TBzTD OP, Weber & Schaer GmbH & Co. KG

TABLE-US-00003 TABLE 3 List of physical test methods used in example 4 Method Standard Determination of viscosity, ML DIN 53523/3, ISO 289-1 (1 + 4) (ME) Vulcameter testing, moving die DIN 53529/3, ISO 6502 method Time to conversion t90% (min) Tensile strain on ring 1 specimens DIN 53 504, ISO 37 at 23° C. Tensile strength (MPa) Shore A hardness DIN 53505/ISO 7619-1 Abrasion test (mm.sup.3) DIN ISO 4649 ASTM D5963 Tear resistance, DIE C (N/mm) ASTM D 624 Tear resistance, Graves (N/mm) DIN ISO 34-1 Tear resistance, DIN (N/mm) DIN ISO 34-1, ISO 34-1

[0189] The mixture formulation is listed in Table 4.

TABLE-US-00004 TABLE 4 Mixture formulation of the S-SBR/BR mixture Mixture 1 Substance (comparative example) Mixture 2 1st Stage S-SBR 96.3 96.3 BR 30 30 Silica 80 80 Silane from comparative example 6.4 — 4 after 3 months' storage Silane from example 3 after 3 — 6.4 months' storage Carbon black 5.0 5.0 ZnO 2.0 2.0 Stearic acid 2.0 2.0 Oil 8.75 8.75 Wax 2.0 2.0 6PPD 2.0 2.0 TMQ 1.5 1.5 2nd Stage 1st stage batch DPG 2.5 2.5 3rd Stage 2nd stage batch CBS 1.6 1.6 Sulfur 2.0 2.0 TBzTD 0.2 0.2

[0190] The mixture preparation is described in Table 5.

TABLE-US-00005 TABLE 5 Mixture production of the S-SBR/BR mixture 1st Stage GK 1.5 E, feed temp. 60° C., 70 rpm, filling factor 0.61 Batch temp.: 145-165° C. 0.0-0.15′ Polymers, TMQ, 6PPD 0.15-1.15′ 1/2 silica, silane 1.15-1.15′ Vent, purge 1.15-2.15′ a) premix carbon black and oil and add together b) 1/2 silica c) remaining constituents from the first stage 2.15-2.15′ Vent, purge 2.15-3.45′ ZnO and stearic acid Mix at 140-160° C., optionally varying speed Eject About 45 sec, on the roll (4 mm gap), eject sheet Storage: 24 h/RT 2nd Stage GK, 1.5 E, feed temp. 75° C., 75 rpm, filling factor 0.59 Batch temp.: 145-165° C. 0.0-1.0′ 1st stage batch 1.0-3.0′ DPG, mix at 145-155° C., optionally varying speed 3.0-3.0′ Eject About 45 sec, on the roll (4 mm gap), eject sheet Storage: 4-24 h/RT 3rd Stage GK, 1.5 E, feed temp. 50° C., 55 rpm, filling factor 0.57 Batch temp.: 90-110° C. 0.0-2.0′ 2nd stage batch, accelerator, sulfur 2.0-2.0′ Eject and process on the roll for about 20 sec, with gap 3-4 mm Storage: 12 h/RT

[0191] The results of physical tests on the rubber mixtures specified here and vulcanizates thereof are listed in Table 6. The vulcanizates were produced from the untreated mixtures from the third stage by heating at 165° C. for 20 min under 130 bar. Mixture 2 with the silane prepared by the process according to the invention shows improved tear resistance.

TABLE-US-00006 TABLE 6 Results of physical tests on the rubber mixtures and their vulcanizates Mixture 1 Method (comparative example) Mixture 2 Untreated mixture ML (1 + 4) at 100° C. 3rd stage 55 53 MDR: 165° C.; 0.5° t 90% 6.1 6.0 Vulcanizate Tensile strength at 23° C./MPa 13.4 15.0 Shore A hardness/SH 61 62 DIN abrasion/mm.sup.3 71 72 Tear resistance, DIE C/(N/mm) 35.2 41.0 Tear resistance, Graves (N/mm) 34.7 40.2 Tear resistance DIN (N/mm) 17.1 18.0