Benzothiazole-containing silanes, method for the preparation and use thereof

Abstract

The invention relates to benzothiazole-containing silanes of the formula I ##STR00001##
which are prepared by reacting benzothiazole-containing silanes of the formula II ##STR00002##
with a compound of formula III
R.sup.2—H  (III). The benzothiazole-containing silanes of the formula I can be used in rubber mixtures.

Claims

1. A benzothiazole-containing silane of the formula (I): ##STR00008## wherein: R.sup.1 is the same or different and is an R.sup.4O— group with R.sup.4 being H, methyl, ethyl, propyl, C9-C30 branched or unbranched monovalent alkyl, alkenyl, aryl or aralkyl group, R.sup.2 is an alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6 with R.sup.5 being the same or different and being a branched or unbranched, saturated or unsaturated, aliphatic divalent C1-C30 hydrocarbon group, m is 1 to 30, and R.sup.6 is a branched or unbranched C1-C30-alkyl group, R.sup.3 is a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group, and x=2-10, and n=0, 1 or 2.

2. The benzothiazole-containing silane according to claim 1, wherein R.sup.1 is methoxy or ethoxy.

3. The benzothiazole-containing silane according to claim 1, wherein R.sup.2=—O—(CH.sub.2CH.sub.2O).sub.5—C.sub.13H.sub.27.

4. The benzothiazole-containing silane according to claim 1, wherein: R.sup.1=—O—C.sub.2H.sub.5, R.sup.2=—O—(CH.sub.2CH.sub.2O).sub.5—C.sub.13H.sub.27, R.sup.3=(CH.sub.2).sub.3, X=2, and n=2.

5. A process for preparing the benzothiazole-containing silane of claim 1, comprising: reacting a benzothiazole-containing silane of the formula (II): ##STR00009## with a compound of formula (III):
R.sup.2—H  (III), to obtain the benzothiazole-containing silane, wherein: R.sup.1 is the same or different and is an R.sup.4O— group with R.sup.4 being H, methyl, ethyl, propyl, C9-C30 branched or unbranched monovalent alkyl, alkenyl, aryl or aralkyl group, R.sup.2 is an alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6 with R.sup.5 being the same or different and being a branched or unbranched, saturated or unsaturated, aliphatic divalent C1-C30 hydrocarbon group, m is 1 to 30, and R.sup.6 is a branched or unbranched C1-C30-alkyl group, R.sup.3 is a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group, and x=2-10, and n=0, 1 or 2.

6. The process according to claim 5, wherein the reaction is conducted in the presence of a catalyst with elimination of R.sup.1—H.

7. A filled rubber mixture, comprising the benzothiazole-containing silane of claim 1 as a coupling reagent.

8. A rubber mixture, comprising: (A) a rubber or a mixture of rubbers, (B) a filler, and (C) at least one benzothiazole-containing silane of claim 1.

9. The rubber mixture according to claim 8, wherein a ratio of the at least one benzothiazole-containing silane to a vulcanization accelerator contained in the rubber mixture is greater than 5.

10. The rubber mixture according to claim 8, comprising a natural rubber.

Description

EXAMPLES

Comparative Example 1: Preparation of 2-[[3-(triethoxysilyl)propyl]dithio]benzothiazole

(1) 2-[[3-(Triethoxysilyl)propyl]dithio]benzothiazole is prepared as described in U.S. Pat. No. 6,465,581 in Example 1, but with CH.sub.2Cl.sub.2 as solvent.

Example 1: Preparation of 2-[[((3,6,9,12,15-pentaoxaoctacosoxy)(diethoxy)silyl)propyl]dithio]benzothiazole

(2) To 2-[[3-(triethoxysilyl)propyl]dithio]benzothiazole (0.150 mol) from Comparative Example 1 are added 3,6,9,12,15-pentaoxaoctacosan-1-ol (0.150 mol) and Ti(OnBu).sub.4 (0.05% by weight/2-[[3-(triethoxysilyl)propyl]dithio]benzothiazole). The mixture is heated to 140° C., the ethanol formed is distilled off and, after 1 h, a pressure of 400-600 mbar is established. After 1 h, the pressure is reduced to 16-200 mbar and the mixture is stirred for 4 h. Subsequently, the reaction mixture is allowed to cool to room temperature and the reaction product is filtered. 2-[[((3,6,9,12,15-Pentaoxaoctacosoxy)(diethoxy)silyl)propyl]dithio]benzothiazole (yield: 85%, transesterification level 31%=0.93 mol polyether alcohol/Si) is obtained as a viscous liquid.

(3) The purity is determined by means of .sup.13C NMR. In the NMR, the shift of the CH.sub.2 group of 61.8 ppm (adjacent to the OH group) compared to the bound variant at 62.1 ppm is characteristic, and it is possible to make a comparison against remaining epoxy groups on the silicon atom at 58.0 ppm.

Example 2: Preparation of 2-[[((bis-3,6,9,12,15-pentaoxaoctacosoxy)(ethoxy)silyl)propyl]dithio]benzothiazole

(4) To 2-[[3-(triethoxysilyl)propyl]dithio]benzothiazole (0.150 mol) from Comparative Example 1 are added 3,6,9,12,15-pentaoxaoctacosan-1-ol (0.300 mol) and Ti(OnBu).sub.4 (0.05% by weight/2-[[3-(triethoxysilyl)propyl]dithio]benzothiazole). The mixture is heated to 140° C., the ethanol formed is distilled off and, after 1 h, a pressure of 400-600 mbar is established. After 1 h, the pressure is reduced to 16-200 mbar and the mixture is stirred for 4 h. Subsequently, the reaction mixture is allowed to cool to room temperature and the reaction product is filtered. 2-[[((Bis-3,6,9,12,15-pentaoxaoctacosoxy)(ethoxy)silyl)propyl]dithio]benzothiazole (yield: 98%, transesterification level 65%=1.95 mol polyether alcohol/Si) is obtained as a viscous liquid.

(5) The purity is determined by means of .sup.13C NMR. In the NMR, the shift of the CH.sub.2 group of 61.8 ppm (adjacent to the OH group) compared to the bound variant at 62.1 ppm is characteristic, and it is possible to make a comparison against remaining epoxy groups on the silicon atom at 58.0 ppm.

Example 3: Preparation of 2-[[((tris-3,6,9,12,15-pentaoxaoctacosoxy)silyl)propyl]dithio]benzothiazole

(6) To 2-[[3-(triethoxysilyl)propyl]dithio]benzothiazole (0.150 mol) from Comparative Example 1 are added 3,6,9,12,15-pentaoxaoctacosan-1-ol (0.450 mol) and Ti(OnBu).sub.4 (0.05% by weight/2-[[3-(triethoxysilyl)propyl]dithio]benzothiazole). The mixture is heated to 140° C., the ethanol formed is distilled off and, after 1 h, a pressure of 400-600 mbar is established. After 1 h, the pressure is reduced to 16-200 mbar and the mixture is stirred for 4 h. Subsequently, the reaction mixture is allowed to cool to room temperature and the reaction product is filtered. 2-[[(Tris-3,6,9,12,15-pentaoxaoctacosoxy)silyl)propyl]dithio]benzothiazole (yield: 94%, transesterification level >95%=>2.85 mol polyether alcohol/Si) is obtained as a viscous liquid.

(7) The purity is determined by means of .sup.13C NMR. In the NMR, the shift of the CH.sub.2 group of 61.8 ppm (adjacent to the OH group) compared to the bound variant at 62.1 ppm is characteristic, and it is possible to make a comparison against remaining epoxy groups on the silicon atom at 58.0 ppm.

Example 4: Rubber Mixtures

(8) In this example, the silanes according to the invention are compared to the benzothiazole-containing silanes known from the prior art.

(9) The formulation used for the rubber mixtures is specified in Table 1 below. In this table, the unit phr means parts by weight based on 100 parts of the crude rubber employed.

(10) The inventive silane I used for example mixture I is the inventive silane prepared in Example I. The structure thereof corresponds to the general formula I with R.sup.1=ethoxy, R.sup.2=O(C.sub.2H.sub.4O).sub.5C.sub.13H.sub.27, R.sup.3=—CH.sub.2CH.sub.2CH.sub.2— and n=2.

(11) The inventive silane II used for example mixture II is the inventive silane II prepared in Example II. The structure thereof corresponds to the general formula I with R.sup.1=ethoxy, R.sup.2=O(C.sub.2H.sub.4O).sub.5C.sub.13H.sub.27, R.sup.3=—CH.sub.2CH.sub.2CH.sub.2— and n=1.

(12) The inventive silane III used for example mixture III is the inventive silane prepared in Example III. The structure thereof corresponds to the general formula I with R.sup.2=O(C.sub.2H.sub.4O).sub.5C.sub.13H.sub.27, R.sup.3=—CH.sub.2CH.sub.2CH.sub.2— and n=0.

(13) The silanes according to the invention were metered in such that the ratio of silane to the vulcanization accelerator Vulkacit CZ exceeds the value of 5.

(14) Typically, amounts of vulcanization accelerator of 1.5 phr to 2.5 phr are used in rubber mixtures. In this example, only 0.8 phr of the vulcanization accelerator Vulkacit CZ is used, and so the ratio of the silane used to the accelerator is greater than 5 in each case.

(15) The silanes Si 266® and Si 363™ used for the reference mixtures I and II are commercially available from Evonik Industries AG. The silane used for reference mixture III is 2-[[3-(triethoxysilyl)propyl]dithio]benzothiazole, prepared in Comparative Example 1.

(16) TABLE-US-00001 TABLE 1 Reference Reference Reference Example Example Example Mixture Mixture Mixture Mixture Mixture Mixture I II III I II III Stage 1 Buna VSL 4526-2 phr 96.3 96.3 96.3 96.3 96.3 96.3 Buna CB 24 phr 30.0 30.0 30.0 30.0 30.0 30.0 ULTRASIL ® 7000 GR phr 80.0 80.0 80.0 80.0 80.0 80.0 Si 266 ® phr 5.80 Si 363 ™ phr 9.00 2-[[3(Triethoxysilyl)propyl] phr 3.68 dithio]benzothiazole Silane from Example 1 phr 7.09 Silane from Example 2 phr 10.51 Silane from Example 3 phr 13.92 N 330 phr 5.0 5.0 5.0 5.0 5.0 5.0 ZnO phr 2.0 2.0 2.0 2.0 2.0 2.0 Stearic acid phr 2.0 2.0 2.0 2.0 2.0 2.0 Oil phr 8.8 8.8 8.8 8.8 8.8 8.8 Wax phr 2.0 2.0 2.0 2.0 2.0 2.0 6 PPD phr 2.0 2.0 2.0 2.0 2.0 2.0 TMQ phr 1.5 1.5 1.5 1.5 1.5 1.5 Stage 2 Stage 1 batch Stage 3 Stage 2 batch CBS phr 0.8 0.8 0.8 0.8 0.8 0.8 Sulfur phr 2.0 2.0 2.0 2.0 2.0 2.0 TBzTD phr 0.4 0.4 0.4 0.4 0.4 0.4
Substances used:

(17) .sup.a The polymer VSL 4526-2 is a solution-polymerized SBR copolymer from Lanxess AG, having a styrene content of 26% by weight and a butadiene content of 74% by weight. The copolymer contains 26% by weight of oil and has a Mooney viscosity (ML 1+4/100° C.) of 50.

(18) The polymer Buna CB 24 is a cis-1,4-polybutadiene (neodymium type) from Bayer AG, having a cis-1,4 content of at least 96% and a Mooney viscosity of 44.

(19) ULTRASIL® 7000 GR is a readily dispersible silica from Evonik Industries AG and has a BET surface area of 170 m.sup.2/g.

(20) The process oil used is Vivatec 500 from Hansen & Rosenthal KG. Vulkanox 4020 (6PPD), Vulkacit CZ (CBS) and Vulkacit D (DPG) are commercial products from Lanxess Deutschland GmbH, and Protektor G3108 is an antiozonant wax from Paramelt B.V. The coactivator Perkacit Richon TBzTD (tetrabenzylthiuram tetrasulfide) is a product from Weber & Schaer GmbH & Co KG.

(21) Corax N330 is a commercial carbon black from Orion Engineered Carbons GmbH.

(22) The mixtures are prepared in three stages in a 1.5 I internal mixer (E-type) at a batch temperature of 155° C. in accordance with the mixing instructions described in Table 2.

(23) TABLE-US-00002 TABLE 2 Stage 1 Settings Mixing unit HF Mixing Group GmbH; type GK 1.5 E Fill level 0.73 Speed 80 min.sup.−1 Ram pressure 5.5 bar Flow temp. 80° C. Mixing procedure 0 to 0.5 min Rubbers 0.5 to 1.0 min 6 PPD, TMQ 1.0 to 2.0 min ½ of silica, silane, ZnO, fatty acid 2.0 min vent and purge 2.0 to 3.0 min ½ of silica, carbon black, TDAE oil, antiozonant wax 3.0 min vent 3.0 to 5.0 min mix at 140-155° C., optionally adjusting temperature by varying speed 5.0 min discharge batch and form a milled sheet on laboratory mixing roll mill for 45 s (laboratory roll mill: diameter 250 mm, length 190 mm, roll nip 4 mm, flow temperature 60° C.) 24 h storage at room temperature Stage 2 Settings Mixing unit as in stage 1 except Fill level 0.69 Speed 80 min.sup.−1 Flow temp. 90° C. Mixing procedure 0 to 1.0 min break up stage 1 batch 1.0 to 3.0 min mix at 140-155° C., optionally adjusting temperature by varying speed 3.0 min discharge batch and form a milled sheet on laboratory mixing roll mill for 45 s (laboratory roll mill: diameter 250 mm, length 190 mm, roll nip 4 mm, flow temperature 60° C.) 3 h storage at room temperature Stage 3 Settings Mixing unit as in stage 1 except Fill level 0.67 Speed 40 min.sup.−1 Flow temp. 50° C. Mixing procedure 0 to 2.0 min break up stage 2 batch, accelerator and sulfur, mix at 100° C., optionally adjusting temperature by varying speed 2.0 min discharge batch and form a milled sheet on laboratory mixing roll mill for 20 s (laboratory roll mill: diameter 250 mm, length 190 mm, roll nip 4 mm, flow temperature 80° C.)

(24) The general process for producing rubber mixtures and vulcanizates thereof is described in “Rubber Technology Handbook”, W. Hofmann, Hanser Verlag 1994.

(25) Rubber testing is effected in accordance with the test methods specified in Table 3.

(26) TABLE-US-00003 TABLE 3 Physical testing Standard/conditions ML 1 + 4, 100° C. (3rd stage) ISO 289-1 Vulkameter test, 165° C. ISO 6502 M.sub.H − M.sub.L t10% t80%-t20% Bar tensile test, 23° C. ISO 37 Shore A hardness, 23° C. ISO 7619-1 Ball rebound, 60° C. ISO 8307 Drop height 500 mm Steel ball 19 mm, 28 g Abrasion resistance, determined with an ISO 4649 instrument with a rotating cylinder drum, 10N Viscoelastic properties ISO 4664-1 0 and 60° C., 16 Hz, initial force 50N and amplitude force 25N Complex modulus E* (MPa) Loss factor tan δ (—)

(27) All mixtures are used to produce test specimens by vulcanization under pressure at 165° C. for fifteen minutes. Table 4 states the rubber data obtained.

(28) TABLE-US-00004 TABLE 4 Reference Reference Reference Example Example Example mixture mixture mixture mixture mixture mixture I II III I II III ML(1 + 4) [100° C.] ME 61 80 96 64 50 44 MDR: 165° C.; 0.5° M.sub.L dNm 2.4 2.8 4.1 2.7 2.0 1.6 M.sub.H dNm 19.6 15.2 27.3 25.7 23.2 20.1 M.sub.H−ML dNm 17.2 12.4 23.2 23.0 21.2 18.5 t 10% min 1.5 0.6 0.3 0.6 1.5 3.1 t 20% min 3.6 0.8 0.9 3.0 4.0 4.4 t 90% min 14.5 3.1 7.5 7.3 7.8 8.4 t 80% − t 20% min 6.4 1.3 5.2 3.2 2.6 2.5 Bar tensile test (6 S1 bars, 23° C.) Tensile strength MPa 15.4 16.6 15.3 17.6 16.3 15.5 100% modulus MPa 2.2 2.6 3.0 2.4 2.3 2.2 300% modulus MPa 9.3 14.6 12.5 11.4 10.5 9.8 300%/100% modulus — 4.2 5.6 4.2 4.8 4.6 4.5 Elongation at break % 442 330 352 417 415 425 Shore A hardness SH 63 59 70 67 65 62 Abrasion resistance mm.sup.3 72 51 70 74 78 89 Ball rebound, 60° C. % 59.5 71.7 59.9 62.5 64.8 64.0 Zwick, 16 Hz, 50N +/− 25N E*; 0° C. MPa 20.7 12.2 41.0 20.0 14.2 12.4 E*; 60° C. MPa 8.8 7.6 16.3 9.7 8.3 7.4 tan δ; 0° C. — 0.439 0.353 0.311 0.392 0.354 0.349 tan δ; 60° C. — 0.153 0.093 0.151 0.127 0.105 0.100

(29) All three example mixtures have a lower Mooney viscosity ML (1+4) [100° C.] than the reference mixtures II and Ill containing the silanes known from the prior art. The comparison with the reference mixture I containing the conventional silane Si 266® shows that the advantageous rubber values profile of the reference mixtures II and III is maintained in the example mixtures. The modulus at 300% elongation and the 300%/100% modulus strengthening index are still at a much higher level compared to reference mixture I. The hysteresis loss, expressed by the distinct lowering in the tan 6, 60° C. value, is greatly reduced.

(30) It is surprising, and unexpected to the person skilled in the art, that the example mixture I having the lowest dosage of the silanes according to the invention has the most balanced rubber values profile. It has the highest dynamic modulus E*, 0° C. of the example mixtures. The Mooney viscosity is in the same order of magnitude as reference mixture I containing the conventional silane Si 266®. There is an increase in tensile strength compared to the reference mixtures II and Ill. At the same time, it has a higher elongation at break.

Example 5

(31) In this example, the silanes according to the invention in a natural rubber-containing rubber mixture are compared to the benzothiazole-containing silanes known from the prior art.

(32) The formulation used for the rubber mixtures is specified in Table 5 below. The unit phr again means parts by weight based on 100 parts of the raw rubber used. The silane dosages are matched to the amount of silica used.

(33) The inventive silane I used for example mixture I is the inventive silane prepared in Example I. The structure thereof corresponds to the general formula I

(34) with R.sup.1=ethoxy, R.sup.2=O(C.sub.2H.sub.4O).sub.5C.sub.13H.sub.27, R.sup.3=—CH.sub.2CH.sub.2CH.sub.2— and n=2.

(35) The inventive silane II used for example mixture II is the inventive silane prepared in Example II.

(36) The structure thereof corresponds to the general formula I

(37) with R.sup.1=ethoxy, R.sup.2=O(C.sub.2H.sub.4O).sub.5C.sub.13H.sub.27, R.sup.3=—CH.sub.2CH.sub.2CH.sub.2— and n=1.

(38) The inventive silane III used for example mixture III is the inventive silane prepared in Example III.

(39) The structure thereof corresponds to the general formula I

(40) with R.sup.2=O(C.sub.2H.sub.4O).sub.5C.sub.13H.sub.27, R.sup.3=—CH.sub.2CH.sub.2CH.sub.2— and n=0.

(41) The silanes Si 266® and Si 363™ used for the reference mixtures I and II are commercially available from Evonik Industries AG. The silane used for reference mixture III is 2-[[3-(triethoxysilyl)propyl]dithio]benzothiazole, prepared in Comparative Example 1. The other chemicals are obtainable as described in Example 4.

(42) The silanes according to the invention are used in equimolar dosages.

(43) TABLE-US-00005 TABLE 5 Reference Reference Reference Example Example Example mixture mixture mixture mixture mixture mixture I II III I II III Stage 1 SMR 10 phr 100.0 100.0 100.0 100.0 100.0 100.0 N234 phr ULTRASIL ® 7000 GR phr 55.0 55.0 55.0 55.0 55.0 55.0 Si 266 ® phr 5.0 Si 363 ™ phr 6.2 2-[[3(Triethoxysilyl)propyl]- phr 2.5 dithio]benzothiazole Silane from Example 1 phr 4.9 Silane from Example 2 phr 7.2 Silane from Example 3 phr 9.6 Stearic acid phr 3.0 3.0 3.0 3.0 3.0 3.0 ZnO phr 3.0 3.0 3.0 3.0 3.0 3.0 6-PPD phr 1.0 1.0 1.0 1.0 1.0 1.0 TMQ phr 1.0 1.0 1.0 1.0 1.0 1.0 Wax phr 1.0 1.0 1.0 1.0 1.0 1.0 Stage 2 First stage batch Stage 3 Second stage batch CBS phr 1.0 1.0 1.0 1.0 1.0 1.0 Sulfur phr 2.0 2.0 2.0 2.0 2.0 2.0

(44) The mixtures are prepared in three stages in a 1.5 I internal mixer (E-type) at a batch temperature of 150° C. in accordance with the mixing instructions described in Table 6. All mixtures were used to produce test specimens by vulcanization under pressure at 150° C. Rubber testing is effected in accordance with the test methods specified in Table 3. The results are shown in Table 7.

(45) TABLE-US-00006 TABLE 6 Stage 1 Settings Mixing unit HF Mixing Group GmbH; type GK 1.5 E Fill level 0.73 Speed 80 min.sup.−1 Ram pressure 5.5 bar Flow temp. 80° C. Mixing procedure 0 to 0.5 min Rubber 0.5 to 1.5 min ½ of silica, silane, ZnO, fatty acid 1.5 min vent and purge 1.5 to 2.5 min ½ of silica, 6 PPD, TMQ, antiozonant wax 2.5 min vent and purge 2.5 to 4.0 min mix at 140-155° C. 4.0 min vent 4.0 to 5.5 min mix at 140-155° C., optionally adjusting temperature by varying speed 5.5 min discharge batch and form a milled sheet on laboratory mixing roll mill for 45 s (laboratory roll mill: diameter 250 mm, length 190 mm, roll nip 4 mm, flow temperature 60° C.) 23 h storage at room temperature Stage 2 Settings Mixing unit as in stage 1 except Fill level 0.69 Speed 80 min.sup.−1 Flow temp. 90° C. Mixing procedure 0 to 1.0 min break up stage 1 batch 1.0 to 3.0 min mix at 140-155° C., optionally adjusting temperature by varying speed 3.0 min discharge batch and form a milled sheet on laboratory mixing roll mill for 45 s (laboratory roll mill: diameter 250 mm, length 190 mm, roll nip 4 mm, flow temperature 60° C.) 3 h storage at room temperature Stage 3 Settings Mixing unit as in stage 1 except Fill level 0.67 Speed 40 min.sup.−1 Flow temp. 50° C. Mixing procedure 0 to 2.0 min break up stage 2 batch, accelerator and sulfur, mix at 100° C., optionally adjusting temperature by varying speed 2.0 min discharge batch and form a milled sheet on laboratory mixing roll mill for 20 s (laboratory roll mill: diameter 250 mm, length 190 mm, roll nip 4 mm, flow temperature 80° C.)

(46) TABLE-US-00007 TABLE 7 Reference Reference Reference Example Example Example Mixture mixture Mixture mixture mixture mixture I II III I II III ML(1 + 4) [100° C.] ME 60 58 65 63 58 53 MDR: 150° C.; 0.5° M.sub.L dNm 2.2 2.1 2.1 2.2 2.1 1.9 M.sub.H dNm 11.7 10.4 12.5 12.6 12.3 12.5 M.sub.H − M.sub.L dNm 9.5 8.4 10.3 10.5 10.2 10.6 t 10% min 8.3 2.7 3.2 9.5 12.0 11.9 t 20% min 11.7 3.9 8.5 12.8 14.1 13.9 t 90% min 29.2 15.3 23.2 22.6 21.8 20.9 t 80% − t 120% min 12.6 7.7 10.6 7.1 5.6 5.1 min Vulcanization time min 43 26 37 32 30 30 (150° C.) Tensile strength (6 S1 MPa 16.2 15.8 13.7 21.6 21.8 22.4 bars, 23° C.) 100% modulus MPa 1.0 1.0 1.0 1.2 1.2 1.1 300% modulus MPa 3.4 3.2 2.9 4.1 4.4 4.2 300%/100% modulus — 3.4 3.2 2.9 3.4 3.7 3.8 Elongation at break % 719 732 706 795 778 791 Shore A hardness SH 54 50 48 52 54 54 Abrasion resistance mm.sup.3 230 295 299 178 152 149 Ball rebound, 60° C. % 65.4 69.0 69.4 69.5 71.2 72.0 Zwick; 16 Hz; 50N +/− 25N E*; 0° C. MPa 9.0 7.8 7.6 7.3 7.5 7.1 E*; 60° C. MPa 6.3 5.5 6.0 5.6 6.0 5.7 tan δ; 0° C. — 0.241 0.227 0.201 0.208 0.216 0.209 tan δ; 60° C. — 0.144 0.124 0.142 0.113 0.093 0.085

(47) For all three example mixtures, the Mooney viscosities are below that of reference mixture III. All example mixtures have a higher tensile strength and higher 300% moduli than the three reference mixtures. At the same time, there is an increase in elongation at break for all of them. The increased values for 60° C. ball rebound and the lower tan 5, 60° C. values compared to the reference are further advantages.