Silane mixtures and process for preparing same

Abstract

The invention relates to silane mixtures comprising a silane of the formula I
((R.sup.1).sub.y(R.sup.2).sub.3-ySi—R.sup.3—SH  (I)
and a silane of the formula II
(R.sup.1).sub.y(R.sup.2).sub.3-ySi—R.sup.3—(S—R.sup.4).sub.z—Si(R.sup.1).sub.y(R.sup.2).sub.3-y  (II)
where the molar ratio of silane of the formula I to silane of the formula II is 20:80-85:15. The silane mixture according to the invention can be prepared by mixing the silanes of the formula I and silanes of the formula II.

Claims

1. A silane mixture comprising: a silane of formula I
(R.sup.1).sub.y(R.sup.2).sub.3-ySi—R.sup.3—SH  (I) and a silane of formula II
(R.sup.1).sub.y(R.sup.2).sub.3-ySi—R.sup.3—(S—R.sup.4).sub.z—Si(R.sup.1).sub.y(R.sup.2).sub.3-y  (II) wherein R.sup.1 are each independently a C1-C10-alkoxy group, a phenoxy group, a C4-C10-cycloalkoxy group or an alkyl polyether group —O—(R.sup.5—O).sub.r—R.sup.6 wherein R.sup.5 are each independently a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group, r is an integer from 1 to 30 and R.sup.6 is unsubstituted or substituted, branched or unbranched monovalent alkyl, alkenyl, aryl or aralkyl group, R.sup.2 are each independently a C6-C20-aryl group, a C1-C 10-alkyl group, a C2-C20-alkenyl group, a C7-C20-aralkyl group or halogen, R.sup.3 are each independently a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group, R.sup.4 are each independently a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic: divalent C1-C30 hydrocarbon group, and y are each independently 1, 2 or 3, z is 2 or 3, and the molar ratio of the silane of formula I to the silane of formula II is from 20:80 to 85:15.

2. The silane mixture according to claim 1, wherein z is 2.

3. The silane mixture according to claim 1, wherein the silane of the formula I is (EtO).sub.3Si—(CH.sub.2).sub.3—SH and the silane of the formula II is (EtO).sub.3—Si—(CH.sub.2).sub.3—S—(CH.sub.2).sub.6—S—(CH.sub.2).sub.3—Si(OEt).sub.3, (EtO).sub.3-Si—(CH.sub.2).sub.3—Si(OEt).sub.3 or (EtO).sub.3Si—(CH.sub.2).sub.3—S—(CH.sub.2).sub.3Si(OEt).sub.3.

4. The silane mixture according to claim 1, wherein the molar ratio of silane of the formula I to silane of the formula II is 50:50-85:15.

5. A process for preparing a silane mixture according to claim 1, wherein the silane of formula I
(R.sup.1).sub.y(R.sup.2).sub.3-ySi—R.sup.3—SH  (I) and the silane of formula II
(R.sup.1).sub.y(R.sup.2).sub.3-ySi—R.sup.3—(S—R.sup.4).sub.z—Si(R.sup.1).sub.y(R.sup.2).sub.3-y  (II) are mixed in a molar ratio of 20:80-85:15.

6. The process for preparing a silane mixture according to claim 5, wherein z=2.

7. The process for preparing a silane mixture according to claim 5, wherein the molar ratio of the silane of formula I to the silane of formula II is from 50:50 to 85:15.

8. The process for preparing a silane mixture according to claim 7, wherein the silane of formula I is (EtO).sub.3Si—(CH.sub.2).sub.3—SH and the silane of formula II is (EtO).sub.3Si—(CH.sub.2).sub.3—S—(CH.sub.2).sub.6—S—(CH.sub.2).sub.3—Si(OEt).sub.3, (EtO).sub.3Si—(CH.sub.2).sub.8—Si(OEt).sub.3 or (EtO).sub.3Si—(CH.sub.2).sub.3—S—(CH.sub.2).sub.3Si(OEt).sub.3.

Description

EXAMPLES

(1) NMR method: The molar ratios and proportions by mass reported as analysis results in the examples come from .sup.13C NMR measurements with the following indices: 100.6 MHz, 1000 scans, solvent: CDCl.sub.3, internal standard for calibration: tetramethylsilane, relaxation aid: Cr(acac).sub.3; for the determination of the proportion by mass in the product, a defined amount of dimethyl sulfone is added as internal standard and the molar ratios of the products are used to calculate the proportion by mass.

Comparative Example 1

(2) bis(triethoxysilylpropyl) disulfide from Evonik Industries AG.

Comparative Example 2

(3) 3-octanoylthio-1-propyltriethoxysilane, NXT Silane from Momentive Performance Materials.

Comparative Example 3

(4) (3-mercaptopropyl)triethoxysilane.

Comparative Example 4

(5) bistriethoxysilyloctane from ABCR GmbH.

Comparative Example 5: bis(triethoxysilylpropyl) Sulfide

(6) To a solution of chloropropyltriethoxysilane (361 g; 1.5 mol; 1.92 eq) in ethanol (360 ml) was added Na.sub.2S (61.5 g; 0.78 mol; 1.00 eq) in portions at such a rate as to not exceed 60° C. Completion of addition was followed by heating at reflux for 3 h, before leaving to cool to room temperature. The reaction product was freed of precipitated salts by filtration. By distillative purification (0.04 mbar; 110° C.), the product (yield: 73%, purity: >99% by .sup.13C NMR) was obtained as a clear liquid.

Comparative Example 6: 1,6-bis(thiopropyltriethoxysilyl)hexane

(7) Sodium ethoxide (21% in EtOH; 82.3 g; 0.254 mol; 2.05 eq) was metered into mercaptopropyltriethoxysilane (62.0 g; 0.260 mol; 2.10 eq) at such a rate that the reaction temperature did not exceed 35° C. On completion of addition, the mixture was heated at reflux for 2 h. Then the reaction mixture was added to 1,6-dichlorohexane (19.2 g; 0.124 mol; 1.00 eq) at 80° C. over the course of 1.5 h. On completion of addition, the mixture was heated at reflux for 3 h and then allowed to cool down to room temperature. Precipitated salts were filtered off and the product was freed of the solvent under reduced pressure. The product (yield: 88%, purity: >99% in .sup.13C NMR) was obtained as a clear liquid.

Comparative Example 7

(8) 6.84 parts by weight of Comparative Example 1 together with 2.65 parts by weight of Comparative Example 5 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 71% (EtO).sub.3Si(CH.sub.2).sub.3S.sub.2(CH.sub.2).sub.3Si(OEt).sub.3 and 29% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.3Si(OEt).sub.3.

Comparative Example 8

(9) 6.84 parts by weight of Comparative Example 1 together with 3.65 parts by weight of Comparative Example 5 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 64% (EtO).sub.3Si(CH.sub.2).sub.3S.sub.2(CH.sub.2).sub.3Si(OEt).sub.3 and 36% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.3Si(OEt).sub.3.

Comparative Example 9

(10) 6.84 parts by weight of Comparative Example 1 together with 4.87 parts by weight of Comparative Example 5 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 57% (EtO).sub.3Si(CH.sub.2).sub.3S.sub.2(CH.sub.2).sub.3Si(OEt).sub.3 and 43% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.3Si(OEt).sub.3.

Comparative Example 10

(11) 6.84 parts by weight of Comparative Example 2 together with 2.10 parts by weight of Comparative Example 6 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 83% (EtO).sub.3Si(CH.sub.2).sub.3SCO(CH.sub.2).sub.6CH.sub.3 and 17% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.6S(CH.sub.2).sub.3Si(OEt).sub.3.

Comparative Example 11

(12) 6.84 parts by weight of Comparative Example 2 together with 3.15 parts by weight of Comparative Example 6 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 77% (EtO).sub.3Si(CH.sub.2).sub.3SCO(CH.sub.2).sub.6CH.sub.3 and 23% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.6S(CH.sub.2).sub.3Si(OEt).sub.3.

Comparative Example 12

(13) 6.84 parts by weight of Comparative Example 2 together with 4.20 parts by weight of Comparative Example 6 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 71% (EtO).sub.3Si(CH.sub.2).sub.3SCO(CH.sub.2).sub.6CH.sub.3 and 29% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.6S(CH.sub.2).sub.3Si(OEt).sub.3.

Comparative Example 13

(14) 6.84 parts by weight of Comparative Example 2 together with 1.65 parts by weight of Comparative Example 4 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 83% (EtO).sub.3Si(CH.sub.2).sub.3SCO(CH.sub.2).sub.6CH.sub.3 and 17% (EtO).sub.3Si(CH.sub.2).sub.8Si(OEt).sub.3.

Comparative Example 14

(15) 6.84 parts by weight of Comparative Example 2 together with 2.47 parts by weight of Comparative Example 4 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 77% (EtO).sub.3Si(CH.sub.2).sub.3SCO(CH.sub.2).sub.6CH.sub.3 and 23% (EtO).sub.3Si(CH.sub.2).sub.8Si(OEt).sub.3.

Comparative Example 15

(16) 6.84 parts by weight of Comparative Example 2 together with 3.29 parts by weight of Comparative Example 4 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 71% (EtO).sub.3Si(CH.sub.2).sub.3SCO(CH.sub.2).sub.6CH.sub.3 and 29% (EtO).sub.3Si(CH.sub.2).sub.8Si(OEt).sub.3.

Example 1

(17) 6.84 parts by weight of Comparative Example 3 together with 3.21 parts by weight of Comparative Example 6 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 83% (EtO).sub.3Si(CH.sub.2).sub.3SH and 17% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.6S(CH.sub.2).sub.3Si(OEt).sub.3.

Example 2

(18) 6.84 parts by weight of Comparative Example 3 together with 4.81 parts by weight of Comparative Example 6 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 77% (EtO).sub.3Si(CH.sub.2).sub.3SH and 23% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.6S(CH.sub.2).sub.3Si(OEt).sub.3.

Example 3

(19) 6.84 parts by weight of Comparative Example 3 together with 2.52 parts by weight of Comparative Example 4 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 83% (EtO).sub.3Si(CH.sub.2).sub.3SH and 17% (EtO).sub.3Si(CH.sub.2).sub.8Si(OEt).sub.3.

Example 4

(20) 6.84 parts by weight of Comparative Example 3 together with 3.78 parts by weight of Comparative Example 4 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 77% (EtO).sub.3Si(CH.sub.2).sub.3SH and 23% (EtO).sub.3Si(CH.sub.2).sub.8Si(OEt).sub.3.

Example 5

(21) 6.84 parts by weight of Comparative Example 3 together with 2.54 parts by weight of Comparative Example 5 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 83% (EtO).sub.3Si(CH.sub.2).sub.3SH and 17% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.3Si(OEt).sub.3.

Example 6

(22) 6.84 parts by weight of Comparative Example 3 together with 3.81 parts by weight of Comparative Example 5 were weighed into a flat PE bag and mixed. This mixture corresponds to a molar ratio: 77% (EtO).sub.3Si(CH.sub.2).sub.3SH and 23% (EtO).sub.3Si(CH.sub.2).sub.3S(CH.sub.2).sub.3Si(OEt).sub.3.

Example 7: Rubber Tests

(23) The formulation used for the rubber mixtures is specified in Table 1 below. The unit phr means parts by weight based on 100 parts of the raw rubber used. The silane mixtures all contain an identical phr amount of silane of the formula I which reacts with the rubber during the vulcanization and different phr amounts of the silane of the formula II.

(24) TABLE-US-00001 TABLE 1 Mixture 1/ Mixture 2/ Mixture 3/ Mixture 4/ Mixture 5/ Mixture 6/ Mixture 7/ Mixture 8/ phr phr phr phr phr phr phr phr 1st stage NR.sup.a) 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 BR.sup.b) 18.0 18.0 18.0 18.0 18.0 18.0 18.0 18.0 S-SBR.sup.c) 72.0 72.0 72.0 72.0 72.0 72.0 72.0 72.0 Silica.sup.d) 95.0 95.0 95.0 95.0 95.0 95.0 95.0 95.0 TDAE oil.sup.e) 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 6PPD.sup.f) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Antiozonant wax 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Stearic acid 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Comp. Ex. 1 6.8 Comp. Ex. 7 9.5 Comp. Ex. 8 10.5 Comp. Ex. 9 11.7 Comp. Ex. 5 6.1 Comp. Ex. 2 6.8 Comp. Ex. 10 8.9 Comp. Ex. 11 10.0 Comp. Ex. 12 Comp. Ex. 13 Comp. Ex. 14 Comp. Ex. 15 Comp. Ex. 4 Comp. Ex. 3 2nd stage Stage 1 batch 3rd stage Stage 2 batch DPG.sup.g) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 CBS.sup.h) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Sulfur.sup.i) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Mixture 9/ Mixture 10/ Mixture 11/ Mixture 12/ Mixture 13/ Mixture 14/ phr phr phr phr phr phr 1st stage NR.sup.a) 10.0 10.0 10.0 10.0 10.0 10.0 BR.sup.b) 18.0 18.0 18.0 18.0 18.0 18.0 S-SBR.sup.c) 72.0 72.0 72.0 72.0 72.0 72.0 Silica.sup.d) 95.0 95.0 95.0 95.0 95.0 95.0 TDAE oil.sup.e) 50.0 50.0 50.0 50.0 50.0 50.0 6PPD.sup.f) 2.0 2.0 2.0 2.0 2.0 2.0 Antiozonant wax 2.0 2.0 2.0 2.0 2.0 2.0 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 Stearic acid 2.5 2.5 2.5 2.5 2.5 2.5 Comp. Ex. 1 Comp. Ex. 7 Comp. Ex. 8 Comp. Ex. 9 Comp. Ex. 5 Comp. Ex. 2 Comp. Ex. 10 Comp. Ex. 11 Comp. Ex. 12 11.0 Comp. Ex. 13 8.5 Comp. Ex. 14 9.3 Comp. Ex. 15 10.1 Comp. Ex. 4 6.8 Comp. Ex. 3 6.8 2nd stage Stage 1 batch 3rd stage Stage 2 batch DPG.sup.g) 2.0 2.0 2.0 2.0 2.0 2.0 CBS.sup.h) 2.0 2.0 2.0 2.0 2.0 2.0 Sulfur.sup.i) 2.0 2.0 2.0 2.0 2.0 2.0 Mixture 15/ Mixture 16/ Mixture 17/ Mixture 18/ Mixture 19/ Mixture 20/ Mixture 21/ Mixture 22/ phr phr phr Inv. phr Inv. phr Inv. phr Inv. phr Inv. phr Inv. 1st stage NR.sup.a) 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 BR.sup.b) 18.0 18.0 18.0 18.0 18.0 18.0 18.0 18.0 S-SBR.sup.c) 72.0 72.0 72.0 72.0 72.0 72.0 72.0 72.0 Silica.sup.d) 95.0 95.0 95.0 95.0 95.0 95.0 95.0 95.0 TDAE oil.sup.e) 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 6PPD.sup.f) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Antiozonant wax 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Stearic acid 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Comp. Ex. 5 6.8 Comp. Ex. 6 8.1 Example 1 10.1 Example 2 11.7 Example 3 9.4 Example 4 10.6 Example 5 9.4 Example 6 10.7 2nd stage Stage 1 batch 3rd stage Stage 2 batch DPG.sup.g) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 CBS.sup.h) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Sulfur.sup.i) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Substances used: .sup.a)NR TSR: natural rubber (TSR = technically specified rubber). .sup.b)Europrene Neocis BR 40, from Polimeri. .sup.c)S-SBR: Sprintan ® SLR-4601, from Trinseo. .sup.d)Silica: ULTRASIL ® VN 3 GR from Evonik Industries AG (precipitated silica, BET surface area = 175 m.sup.2/g). .sup.e)TDAE oil: TDAE = treated distillate aromatic extract. .sup.f)6PPD: N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD). .sup.g)DPG: N,N′-diphenylguanidine (DPG). .sup.h)CBS: N-cyclohexyl-2-benzothiazolesulfenamide. .sup.i)Sulfur: ground sulfur.

(25) The mixture was produced by processes customary in the rubber industry in three stages in a laboratory mixer of capacity 300 millilitres to 3 litres, by first mixing, in the first mixing stage (base mixing stage), all the constituents apart from the vulcanization system (sulfur and vulcanization-influencing substances) at 145 to 165° C., target temperatures of 152 to 157° C., for 200 to 600 seconds. In the second stage, the mixture from stage 1 was thoroughly mixed once more, performing what is called a remill. Addition of the vulcanization system in the third stage (ready-mix stage) produced the finished mixture, with mixing at 90 to 120° C. for 180 to 300 seconds. All the mixtures were used to produce test specimens by vulcanization under pressure at 160° C.-170° C. after t95-t100 (measured on a moving disc rheometer to ASTM D 5289-12/ISO 6502).

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

(27) Rubber testing was effected in accordance with the test methods specified in Table 2. The results of the rubber testing are reported in Table 3.

(28) TABLE-US-00002 TABLE 2 Physical testing Standard/conditions Viscoelastic properties of the RPA (rubber process analyzer) vulcanizate at 70° C., strain sweep, 1 in accordance with ASTM Hz, 1%-100% elongation D6601, values recorded Loss factor tan δ at 10% elongation during the second strain sweep Viscoelastic properties of the from dynamic-mechanical vulcanizate at 55° C. measurement according to Maximum loss factor tan δ DIN 53 513, strain sweep Resilience at 70° C. Resilience/% according to ISO 4662 Tensile test at 23° C. according to DIN 53 504 Stress value at 200% elongation/MPa Abrasion, 10 N at 23° C. determined with an instrument Abrasion/mm.sup.3 having a rotating cylinder drum, loss of volume reported according to ISO 4649

(29) TABLE-US-00003 TABLE 3 Mixture 1 Mixture 2 Mixture 3 Mixture 4 Mixture 5 Mixture 6 tan δ (10%) at 70° C. 0.188 0.190 0.186 0.186 0.213 0.177 Maximum tan δ at 55° C. 0.174 0.168 0.169 0.164 0.207 0.179 Resilience/% 44.0 46.2 48.3 48.8 40.9 45.1 200% modulus/MPa 4.5 5.0 5.2 5.3 2.9 4.5 Abrasion/mm.sup.3 146 147 146 159 215 133 Mixture 7 Mixture 8 Mixture 9 Mixture 10 Mixture 11 Mixture 12 tan δ (10%) at 70° C. 0.171 0.171 0.169 0.238 0.236 0.235 Maximum tan δ at 55° C. 0.172 0.168 0.166 0.210 0.217 0.205 Resilience/% 47.5 49.1 49.3 38.6 38.4 39.2 200% modulus/MPa 4.7 4.9 5.0 1.8 1.8 1.8 Abrasion/mm.sup.3 134 143 143 282 287 268 Mixture 13 Mixture 14 Mixture 15 Mixture 16 tan δ (10%) at 70° C. 0.275 0.174 0.240 0.174 Maximum tan δ at 55° C. 0.218 0.176 0.209 0.192 Resilience/% 31.7 46.6 34.2 42.1 200% modulus/MPa 1.1 4.4 1.4 2.5 Abrasion/mm.sup.3 320 99 234 196 Mixture 17 Mixture 18 Mixture 19 Mixture 20 Mixture 21 Mixture 22 Inv. Inv. Inv. Inv. Inv. Inv. tan δ (10%) at 70° C. 0.144 0.149 0.148 0.141 0.155 0.152 Maximum tan δ at 55° C. 0.140 0.139 0.153 0.138 0.154 0.144 Resilience/% 52.9 54.7 51.9 53.7 51.5 52.9 200% modulus/MPa 5.9 6.3 7.1 7.6 6.1 6.4 Abrasion/mm.sup.3 81 86 67 76 72 85

(30) Compared to the comparative mixtures, the mixtures according to the invention feature advantages in rolling resistance (tan 6 measurements, resilience at 7000). Abrasion and reinforcement of the mixtures according to the invention are likewise improved compared to the prior art (abrasion, 200% modulus).