Oligomeric organosilanes, the production thereof and the use thereof in rubber mixtures

Abstract

The present invention relates to oligomeric organosilanes containing at least two different structural units within a molecule, selected from the structural units A, B, C and D joined in any desired linear, branched or cyclic arrangement, ##STR00001##
wherein at least one R, R.sup.1, R.sup.2, R.sup.3, R.sup.4 or R.sup.7 group is an alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6,
to the preparation thereof and to the use thereof in rubber mixtures.

Claims

1. An oligomeric organosilane, comprising structural unit A and at least one structural unit selected from structural units B, C and D joined in a linear, branched or cyclic arrangement; ##STR00007## wherein: Y represents H, F, Cl, Br, I, SCN, SH, —S.sub.x—(CH.sub.2).sub.nSiRR.sup.1R.sup.2 or —N(R.sup.8).sub.2; R.sup.8 independently represents H, (C.sub.1-C.sub.16) alkyl, —(CH.sub.2).sub.2NH.sub.2, —(CH.sub.2).sub.2NH—(CH.sub.2).sub.2NH.sub.2 or —(CH.sub.2).sub.2N[(CH.sub.2).sub.2NH.sub.2].sub.2; n represents 1-8; G represents H, F, Cl, Br, I, SCN, SH, —S.sub.x—(CH.sub.2).sub.nSiRR.sup.1R.sup.2 or —N(R.sup.8).sub.2, such that G is different from Y; R, R.sup.1, R.sup.2, R.sup.3, R.sup.4, each independently represent OH, (C.sub.1-C.sub.16)alkyl, (C.sub.2-C.sub.16)alkenyl, (C.sub.6-C.sub.14)aryl, (C.sub.1-C.sub.4)alkoxy, an OSiR.sup.1R.sup.2R.sup.3 group or an alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6; R.sup.5 independently represents a branched or unbranched, saturated or unsaturated, aliphatic divalent C1-C30 hydrocarbon group; m on average is 1 to 30; R.sup.6 represents an unsubstituted or substituted, branched or unbranched C.sub.1-C.sub.30 alkyl group, C.sub.2-C.sub.30 alkenyl group, a C.sub.6-C.sub.14 aryl group, or a C.sub.7-C.sub.40 aralkyl group; R.sup.7 represents an alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6; x on statistical average is 1-6; and z on statistical average is 1-6.

2. The oligomeric organosilane of claim 1, wherein an molecular weight of the oligomeric organosilane is between 400 and 100,000 g/mol.

3. The oligomeric organosilane of claim 1, wherein: the oligomeric organosilane comprises the structural units A and B and C; and R.sup.7 represents the alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6.

4. The oligomeric organosilane of claim 3, wherein; in structural unit A, n represents 3, and Y represents SH; in structural unit B, R.sup.1 represents ethoxy or alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6, R.sup.2 represents ethoxy or alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6, n represents 3, and z represents 2-4; and in structural unit C, R represents phenyl, propyl or octyl, and R.sup.3 represents ethoxy or alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6.

5. The oligomeric organosilane of claim 1, wherein: the oligomeric organosilane comprises the structural units A and B; and R.sup.7 represents the alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6.

6. The oligomeric organosilane of 5, wherein: in structural unit A, n represents 3, and Y represents SH; and in structural unit B, R.sup.1 represents ethoxy or alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6, R.sup.2 represents ethoxy or alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6, n represents 3, and z represents 2-4.

7. The oligomeric organosilane of claim 1, wherein: the oligomeric organosilane comprises the structural units A and D; and R.sup.7 represents the alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6.

8. The oligomeric organosilane of claim 7, wherein: in structural unit A, n represents 3, and Y represents SH; and in structural unit D, G represents Cl or NH.sub.2, n represents 3, and R.sup.4 represents ethoxy or alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6.

9. The oligomeric organosilane of claim 1, wherein: the oligomeric organosilane comprises the structural units A and C and D, R.sup.7 represents the alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6.

10. The oligomeric organosilane of claim 9, wherein: in structural unit A, n represents 3, and Y represents SH; in structural unit C, R represents phenyl, propyl or octyl, and R.sup.3 represents ethoxy or alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6; and in structural unit D, G represents Cl or NH.sub.2, R.sup.4 represents ethoxy or alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6, and n represents 3.

11. The oligomeric organosilane of claim 1, wherein: the oligomeric organosilane comprises the structural units A and C; and R.sup.7 represents the alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6.

12. The oligomeric organosilane of claim 11, wherein: in structural unit A, n represents 3, and Y represents SH; and in structural unit C, R represents phenyl, propyl or octyl, and R.sup.3 represents ethoxy or alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6.

13. A process for preparing the oligomeric organosilane of claim 1, the process comprising: oligomerizing/polymerizing the compound of formula I and at least one of the compounds of formulae II-IV: ##STR00008## in the presence of water at temperatures of 0-150° C., to form an intermediate; and reacting the intermediate with an alkyl polyether alcohol of formula HO—(R.sup.5—O).sub.m—R.sup.6, to form the oligomeric organosilane, wherein: Y, G, R, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, n, m, u, x and z are each as defined in claim 1; and R.sup.9 independently represents H, F, Cl, Br, I, or (C.sub.1-C.sub.16)alkoxy.

14. The process of claim 13, wherein the oligomerizing/polymerizing, the reacting, or both, occurs in the presence of a catalyst.

15. The process of claim 14, wherein: the oligomerizing/polymerizing occurs in the present of HCl as catalyst; and the reacting occurs in the present of tetrabutyl orthotitanate as catalyst.

16. The process of claim 13, wherein the oligomerizing/polymerizing, the reacting, or both, occurs in the presence of a solvent which is ethyl acetate or ethanol.

17. A rubber mixture, comprising the oligomeric organosilane of claim 1.

18. A tire, profile, cable sheath, hose, drive belt, conveyor belt, tyre cover, shoe sole, gasket ring or damping element comprising the rubber mixture of claim 17.

19. An oligomeric organosilane obtained by the process of claim 13.

20. An oligomeric organosilane, comprising structural unit D and at least one structural unit selected from structural units A, B and C, joined in a linear, branched or cyclic arrangement: ##STR00009## wherein: Y represents H, F, Cl, Br, I, SCN, SH, —S.sub.x—(CH.sub.2).sub.nSiRR.sup.1R.sup.2 or —N(R.sup.8).sub.2; R.sup.8 independently represents H, (C.sub.1-C.sub.16) alkyl, —(CH.sub.2).sub.2NH.sub.2, —(CH.sub.2).sub.2NH—(CH.sub.2).sub.2NH.sub.2 or —(CH.sub.2).sub.2N[(CH.sub.2).sub.2NH.sub.2].sub.2; n represents 1-8; G represents H, F, Cl, Br, I, SCN, SH, —S.sub.x—(CH.sub.2).sub.nSiRR.sup.1R.sup.2 or —N(R.sup.8).sub.2, such that G is different from Y; R, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.7 each independently represent OH, (C.sub.1-C.sub.16)alkyl, (C.sub.2-C.sub.16)alkenyl, (C.sub.6-C.sub.14)aryl, (C.sub.1-C.sub.4)alkoxy, an OSiR.sup.1R.sup.2R.sup.3 group or an alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6; R.sup.5 independently represents a branched or unbranched, saturated or unsaturated, aliphatic divalent C1-C30 hydrocarbon group; m on average is 1 to 30; R.sup.6 represents an unsubstituted or substituted, branched or unbranched C.sub.1-C.sub.30 alkyl group, C.sub.2-C.sub.30 alkenyl group, a C.sub.6-C.sub.14 aryl group, or a C.sub.7-C.sub.40 aralkyl group; x on statistical average is 1-6; z on statistical average is 1-6; and at least one R, R.sup.1, R.sup.2, R.sup.3, R.sup.4 or R.sup.7 group is an alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6.

21. A process for preparing the oligomeric organosilane of claim 20, the process comprising: oligomerizing/polymerizing the compound of formula IV and at least one of the compounds of formulae I-III: ##STR00010## in the presence of water at temperatures of 0-150° C., to form an intermediate; and reacting the intermediate with an alkyl polyether alcohol of formula HO—(R.sup.5—O).sub.m—R.sup.6, to form the oligomeric organosilane, wherein: Y, G, R, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, n, m, u, x and z are each as defined in claim 20; and R.sup.9 independently represents H, F, Cl, Br, I, or (C.sub.1-C.sub.16)alkoxy.

Description

EXAMPLES

(1) Octyltriethoxysilane, propyltriethoxysilane, Dynasylan® 9265 (phenyltriethoxysilane), Si 690® (bis(triethoxysilylpropyl) tetrasulphide) and VP Si 263® (3-mercaptopropyltriethoxysilane) are silanes from Evonik Industries.

(2) Marlosol is a polyether alcohol of the formula HO—(R.sup.5—O).sub.m—R.sup.6 where R.sup.5═CH.sub.2CH.sub.2, R.sup.6═C.sub.13H.sub.27 and m=5 from Sasol.

Example 1

(3) Preparation from VP Si 263®/octyltriethoxysilane/Marlosol (1:0.5:0.5)-0.8 eq H.sub.2O.

(4) A stirred apparatus is initially charged with VP Si 263® (417 g) and octyltriethoxysilane (242 g) and heated to 85° C. A mixture of H.sub.2O (38 g) and conc. HCl (0.3 g, 37%) in EtOH (363 g) is added dropwise and then the mixture is stirred for 8.5 h. After the oligomerization reaction has ended, the solvent and alcohol formed in the hydrolysis are removed under reduced pressure. Marlosol (368 g) and tetra-n-butyl titanate (0.5 g) are added and the reaction is heated to 140° C. for 1 h. The EtOH formed is removed by distillation under reduced pressure. The bottom product (793 g, 95% of theory) is a viscous orange liquid.

(5) Density (20° C.): 1.012 g/cm.sup.3

(6) 29Si NMR: 3% silane (VP Si 263®, octyltriethoxysilane), 49% M structures, 40% D structures, 9% T structures

(7) GPC: Mn=967 g/mol, Mw=1234, Mz=1536, PDI=1.2761

(8) Molar ratio of the alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6 to silicon=0.33

Example 2

(9) Preparation from VP Si 2630®/propyltriethoxysilane/Marlosol (1:0.5:0.5)-0.8 eq H.sub.2O

(10) A stirred apparatus is initially charged with VP Si 2630® (417 g) and propyltriethoxysilane (181 g) and heated to 85° C. A mixture of H.sub.2O (38 g) and conc. HCl (0.3 g, 37%) in EtOH (363 g) is added dropwise and then the mixture is stirred for 8 h. After the oligomerization reaction has ended, the solvent and alcohol formed in the hydrolysis are removed under reduced pressure. Marlosol (368 g) and tetra-n-butyl titanate (0.5 g) are added and the reaction is heated to 140° C. for 1 h. The EtOH formed is removed by distillation under reduced pressure. The bottom product (751 g, 94% of theory) is a viscous colourless liquid.

(11) Density (20° C.): 1.029 g/cm.sup.3

(12) 13C NMR: 78.6 mol % SiOEt, 21.4 mol % SiOR

(13) 29Si NMR: <1% silane (VP Si 263®, propyltriethoxysilane), 60% M structures, 35% D structures, 4% T structures

(14) GPC: Mn=757 g/mol, Mw=1066, Mz=1417, PDI=1.4082

(15) Molar ratio of the alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6 to silicon=0.33

Example 3

(16) Preparation from VP Si 263®/phenyltriethoxysilane (Dynasylan® 9265)/Marlosol (1:0.5:0.5)-0.8 eq H.sub.2O

(17) A stirred apparatus is initially charged with VP Si 263® (417 g) and Dynasylan® 9265 (210 g) and heated to 88° C. A mixture of H.sub.2O (38 g) and conc. HCl (0.3 g, 37%) in EtOH (363 g) is added dropwise and then the mixture is stirred for 6 h. After the oligomerization reaction has ended, the solvent and alcohol formed in the hydrolysis are removed under reduced pressure. Marlosol (368 g) and tetra-n-butyl titanate (0.5 g) are added and the reaction is heated to 140° C. for 1 h. The EtOH formed is removed by distillation under reduced pressure. The bottom product (797 g, 99% of theory) is a viscous, pale yellow liquid.

(18) Density (20° C.): 1.050 g/cm.sup.3

(19) 29Si NMR: 3% VP Si 263®, 1% Dynasylan® 9265, 51% M structures, 37% D structures, 8% T structures

(20) GPC: Mn=770 g/mol, Mw=1013, Mz=1300, PDI=1.3156

(21) Molar ratio of the alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6 to silicon=0.33

Example 4

(22) Inventive: Preparation from VP Si 263®/Si 69®/Marlosol (1:0.5:0.5)-0.8 eq H.sub.2O

(23) A stirred apparatus is initially charged with VP Si 263® (417 g) and Si 69® (466 g) and heated to 98° C. A mixture of H.sub.2O (38 g) and conc. HCl (0.3 g, 37%) in EtOH (363 g) is added dropwise and then the mixture is stirred for 8 h. After the oligomerization reaction has ended, the solvent and alcohol formed in the hydrolysis are removed under reduced pressure. Marlosol (368 g) and tetra-n-butyl titanate (0.5 g) are added and the reaction is heated to 140° C. for 1 h. The EtOH formed is removed by distillation under reduced pressure. The bottom product (1028 g, 98% of theory) is a viscous yellow liquid.

(24) Density (20° C.): 1.082 g/cm.sup.3

(25) 1H NMR: 40 mol % SH, 22 mol % S2, 27 mol % S3, 11 mol % Sx

(26) 13C NMR: 87.5 mol % SiOEt, 22.5 mol % SiOR

(27) 29Si NMR: 9% silane, 72% M structures, 19% D structures

(28) GPC: Mn=1317 g/mol, Mw=5501, Mz=12291, PDI=4.1778

(29) Molar ratio of the alkyl polyether group —O—(R.sup.5—O).sub.m—R.sup.6 to silicon=0.33

Comparative Example 5

(30) Reference according to EP 0964021: Preparation from Si 69®/PTEO (1:5)-0.8 eq H.sub.2O

(31) A stirred apparatus is initially charged with Si 69® (240 g) and PTEO (464 g) and heated to 75° C. A mixture of H.sub.2O (45 g) and conc. HCl (0.5 g, 37%) in EtOH (436 g) is added dropwise and then the mixture is stirred for 12 h. After the oligomerization reaction has ended, the solvent and alcohol formed in the hydrolysis are removed under reduced pressure. The bottom product (518 g, >99% of theory) is a viscous yellow liquid.

(32) 29Si NMR: 0% silane PTEO, 0.4% silane Si 69®, 1% M structures of PTEO, 69% M structures of Si 69+D structures of PTEO, 28% D structures of Si 69®+T structures of PTEO, 1% T structures of Si 69®

(33) GPC: Mn=871 g/mol, Mw=1473, Mz=2337, PDI=1.6916

Example 6

(34) 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 by weight of the raw rubber used. The oligomeric silanes are used in isomolar amounts, based on the silane used in situ. The mixtures are prepared in a 1.5 l mixer (E type) at a batch temperature of 155° C.

(35) TABLE-US-00001 TABLE 1 Amount Amount [phr] Amount Amount Amount Amount [phr] Amount Inv. [phr] [phr] [phr] [phr] Ref. [phr] rubber Inv. Inv. Inv. Ref. rubber Ref. mixture rubber rubber rubber rubber mixture rubber I, mixture mixture mixture mixture I II, mixture cont. II, III, IV, “in “in III, inv. cont. cont. cont. Substance situ” situ” comp. ex. 5 ex. 1 inv. ex. 2 inv. ex. 3 inv. ex. 4 1st stage Buna VSL 96.25 96.25 96.25 96.25 96.25 96.25 96.25 5025-2 Buna CB 24 30 30 30 30 30 30 30 Ultrasil 80 80 80 80 80 80 80 7000 GR ZnO RS 2 2 2 2 2 2 2 Edenor ST1 1 1 1 1 1 1 1 Vivatec 500 8.75 8.75 8.75 8.75 8.75 8.75 8.75 Rhenogran 2.5 2.5 2.5 2.5 2.5 2.5 2.5 DPG-80 Protector 2 2 2 2 2 2 2 G 3108 Vulkanox- 2 2 2 2 2 2 2 4020/LG Vulkanox- 1.5 1.5 1.5 1.5 1.5 1.5 1.5 HS/LG Aktiplast 3.5 3.5 3.5 3.5 3.5 3.5 3.5 ST Si 69 ® 6.4 — — — — — — VP Si 363 ® — 10 — — — — — Reference — — 3.1 — — — — silane according to comp. ex. 5 Inv. silane — — — 6.0 — — — according to ex. 1 Inv. silane — — — — 5.6 — — according to ex. 2 Inv. silane — — — — — 5.8 — according to ex. 3 Inv. silane — — — — — — 7.3 according to ex. 4 2nd stage Batch Stage 1 3rd stage Batch Stage 2 Perkacit 0.2 0.2 0.2 0.2 0.2 0.2 0.2 TBzTD Vulkacit 1.6 1.6 1.6 1.6 1.6 1.6 1.6 CZ/EG-C Sulphur 2.1 2.1 2.1 2.1 2.1 2.1 2.1

(36) The polymer VSL 5025-2 is a solution-polymerized SBR copolymer from Bayer AG, having a styrene content of 25% by weight and a vinyl fraction of 50% by weight. The copolymer contains 37.5 phr TDAE oil and has a Mooney viscosity (ML 1+4/100° C.) of 47.

(37) 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±5.

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

(39) The TDAE oil used is Vivatec 500 from Klaus Dahleke KG, Vulkanox 4020 is 6PPD from Lanxess Europe GmbH & Co. KG, Vulkanox HS/LG is TMQ from Lanxess and Protektor G3108 is an antiozonant wax from Paramelt B.V.; ZnO RS is ZnO from Arnsperger Chemikalien GmbH; EDENOR ST1 GS 2.0 is palmitic/stearic acid from Caldic Deutschland GmbH & Co. KG; Aktiplast ST is a plasticizer from RheinChemie, which consists of a blend of hydrocarbons, zinc soaps and fillers. Rhenogran DPG-80 consists of 80% DPG on an EVA/EPDM carrier from RheinChemie, and Vulkacit CZ is CBS from Lanxess Europe GmbH & Co. KG. Perkacit TBzTD (tetrabenzylthiuram disulphide) is a product from Flexsys N.V.

(40) The rubber mixture is produced in three stages in an internal mixer according to Table 2.

(41) TABLE-US-00002 TABLE 2 Stage 1 Settings Mixing unit Werner & Pfleiderer GK 1.5E Speed 80 min.sup.−1 Ram pressure 5.5 bar Flow temp. 80° C. Mixing process 0 to 0.5 min Buna VSL 5025-1 + Buna CB 24 0.5 min TMQ, 6PPD 0.5 bis 1 min mix 1 to 2 min ½ Ultrasil 7000 GR, silane or oligomeric organosilanes, ZnO 2 min clean and ventilate 2 to 3 min ½ Ultrasil 7000 GR, Protector G3108, stearic acid, Vivatec 500, DPG, plasticizer 3 min clean and ventilate 3 to 4 min mix and discharge at 150-160° C. Stage 2 Settings Mixing unit as in stage 1 except: Speed 90 min.sup.−1 Mixing process 0 to 1 min break up stage 1 batch 1 to 3 min mix at 155° C. 3 min discharge Stage 3 Settings Mixing unit as in stage 1 except Speed 40 min.sup.−1 Flow temp. 50° C. Mixing process 0 to 0.5 min stage 2 batch 0.5 to 2 min accelerator and sulphur 2 min discharge and form milled sheet on laboratory roll mill (diameter 200 mm, length 450 mm, flow temperature 50° C.) Homogenize: form a milled sheet with roll gap 3-4 mm for 20 s, and within a further 40 s: cut and fold over 3* to the left, 3* to the right and roll 3* with a narrow roll gap (3 mm) and then draw off a milled sheet. Batch temp. <110° C.

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

(43) The rubber testing is effected by the test methods specified in Table 3.

(44) TABLE-US-00003 TABLE 3 Physical testing Standard/conditions Moving die method: minimum torque DIN 53529/3, ISO 6502 Ring tensile test, 23° C. DIN 53504, ISO 37 Stress values DIN abrasion DIN ISO 4649, ISO 4649 Shore hardness DIN 53505, ISO 7619-1 Tear resistance, die C ASTM D 624 Ball rebound, 70° C. ASTM D 2632 Viscoelastic properties DIN 53 513, ISO 2856 0 and 60° C., 16 Hz, initial force 50 N and amplitude force 25 N Complex modulus E* (MPa)

(45) The vulcanization is effected at a temperature of 165° C. for a period of 15 minutes. Table 4 reports the rubber data for raw mixture and vulcanizate.

(46) TABLE-US-00004 TABLE 4 Inv. rubber Inv. Inv. Inv. Ref. Ref. Ref. mixture rubber rubber rubber rubber rubber rubber I, mixture mixture mixture mixture I mixture mixture cont. II, III, IV, “in II, III, inv. cont. cont. cont. Substance situ” “in situ” comp. ex. 5 ex. 1 inv. ex. 2 inv. ex. 3 inv. ex. 4 Crude mixture results: Moving die 2.3 2.9 2.1 2.7 2.1 1.9 method: minimum torque after 3rd stage [dNm] Vulcanizate results: 50% stress 1.2 1.05 1.15 1.2 1.1 1.1 value [mPa] 200% stress 7.2 4.8 8.9 9.2 8.3 7.6 value [mPa] Strengthening 6.0 4.6 7.7 7.7 7.5 6.9 index: 200%/50% stress value [—] DIN abrasion 95 105 104 67 61 69 72 [mm.sup.3] Shore 60 55 60 56 58 55 58 hardness Ball rebound, 65.0 68.8 63.0 72.1 71.6 70.8 70.1 70° C. [%] Tear 40.2 49 33.4 36.7 44.4 40.7 37.5 resistance, die C [N/mm] MTS, 16 Hz, 0.454 0.412 0.476 0.449 0.478 0.462 0.474 initial force 50 N, ampl. force 25 N, 0° C. [MPa] MTS, 16 Hz, 0.109 0.108 0.130 0.087 0.093 0.093 0.096 initial force 50 N, ampl. force 25 N, 60° C. [MPa]

(47) The rubber mixtures containing the inventive oligomeric silanes show improved processing characteristics (lower torque after the 3rd mixing stage), improved strengthening characteristics (higher moduli and better reinforcement index), improved rolling resistance and improved tear resistance compared to the isomolar in situ mixture or the oligomeric silane according to EP 0964021.