Silane, rubber mixture containing the silane, and vehicle tire having the rubber mixture in at least one component

Abstract

The invention relates to a silane, to a rubber mixture containing the silane and to a vehicle tire comprising the rubber mixture in at least one component. The silane according to the invention has the following formula I)
(R.sup.1).sub.oSiR.sup.2X-A-Y[R.sup.7Y].sub.mR.sup.7S-G,I)
wherein according to the invention it has a spacer group between the silyl group and the S-G moiety, wherein the spacer group has an aromatic group A and at least one further aromatic group and/or an alkylene group and also the linking units X and Y, wherein the group X is selected from the groups HNC(?O), C(?O)NH, C(?O)O, OC(?O), OC(?O)NH, HNC(?O)O, R.sup.3NC(?O)NR.sup.3, R.sup.3NC(?NR.sup.3)NR.sup.3, R.sup.3NC(?S)NR.sup.3, wherein at least one R.sup.3 within the group X is a hydrogen atom, and wherein the groups Y are selected from the groups HNC(?O), C(?O)NH, C(?O)O, OC(?O), OC(?O)NH, HNC(?O)O, R.sup.4NC(?O)NR.sup.4, R.sup.4NC(?NR.sup.4)NR.sup.4, R.sup.4NC(?S)NR.sup.4, wherein at least one R.sup.4 within each group Y is a hydrogen atom, and wherein the radicals R.sup.7 are selected from aromatic groups A and alkylene radicals having 1 to 20 carbon atoms, which may have cyclic, branched and/or aliphatically unsaturated groups; and wherein G is a hydrogen atom or a C(?O)R.sup.8 group or a SiR.sup.8.sub.3 group, wherein R.sup.8 is selected from linear, branched and cyclic C.sub.1-C.sub.20-alkyl groups, C.sub.6-C.sub.20-aryl groups, C.sub.2-C.sub.20-alkenyl groups and C.sub.7-C.sub.20-aralkyl groups, and wherein m can take the values 0 to 4. The rubber mixture according to the invention contains at least one silane according to the invention.

Claims

1. A silane of formula I):
(R))SiR2-X-A-Y[RY-]n-RS-G,I) wherein o can be 1, 2 or 3; and, the radicals R.sup.1 within the silyl groups (R.sup.1).sub.oSi are identical or different from each other and are selected from alkoxy groups having 1 to 10 carbon atoms, cycloalkoxy groups having 4 to 10 carbon atoms, phenoxy groups having 6 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms, aralkyl groups having 7 to 20 carbon atoms, halides, or the radicals R1 are alkyl polyether groups O(R.sup.6O),R.sup.5 wherein R.sup.6 are identical or different and are branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic bridging C.sub.1-C.sub.30 hydrocarbon groups, r is an integer from 1 to 30, and R.sup.5 are unsubstituted or substituted, branched or unbranched, terminal alkyl, alkenyl, aryl or aralkyl groups, or two R.sup.1 form a cyclic dialkoxy group having 2 to 10 carbon atoms in which case 0 is <3, or two or more silanes of formula I) can be bridged via radicals R.sup.1; and wherein the radical R.sup.2 is selected from the group consisting of linear and branched alkylene groups having 1 to 20 carbon atoms, cycloalkyl groups having 4 to 12 carbon atoms, aryl groups having 6 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms and aralkyl groups having 7 to 20 carbon atoms; and wherein the group X is selected from the groups HNC(?O), C(?O)NH, C(?O)O, OC(?O), OC(?O)NH, HNC(?O)O, R.sup.3NC(?O)NR.sup.3, R.sup.3NC(?NR.sup.3)NR.sup.3, R.sup.3NC(?S)NR.sup.3, wherein the radicals R3 within the group X may be identical or different and are selected from a hydrogen atom or as defined for R2 under the condition that at least one R3 within the group X is a hydrogen atom; and wherein the groups A within a molecule may be identical or different from each other and are aromatic groups; and wherein the radicals R within a molecule may be identical or different and are selected from aromatic groups A and alkylene radicals having 1 to 20 carbon atoms, which may have cyclic, branched and/or aliphatically unsaturated groups; and wherein G is a hydrogen atom or a C(?O)R.sup.8 group or a SiR.sup.8.sub.3; group, wherein R.sup.8 is selected from linear, branched and cyclic C.sub.1-C.sub.20-alkyl groups, C.sub.6-C.sub.20-aryl groups, C.sub.2-C.sub.20-alkenyl groups and C.sub.7-C.sub.20-aralkyl groups; and wherein the groups Y within a molecule may be identical or different from each other and are selected from the groups HNC(?O), C(?O)NH, C(?O)O, OC(?O), OC(?O)NH, HNC(?O)O, R.sup.4NC(?O)NR.sup.4, R4NC(?NR.sup.4)NR.sup.4, R.sup.4NC(?S)NR.sup.4, wherein the radicals R.sup.4 within a group Y and within a molecule may be identical or different and are selected from a hydrogen atom or as defined for R.sup.2 under the condition that at least one R.sup.4 within each group Y is a hydrogen atom; and wherein m is an integer from 0 to 4, and wherein the silane may also be in the form of oligomers which are formed by hydrolysis and condensation of silanes of formula I).

2. The silane as claimed in claim 1, wherein m=0.

3. The silane as claimed in claim 1, wherein X is selected from the group consisting of: HNC(?O), C(?O)NH, OC(?O)NH, HNC(?O)O, R.sup.3NC(?O)NR.sup.3, R.sup.3NC(?NR.sup.3)NR.sup.3, and R.sup.3NC(?S)NR.sup.3.

4. The silane as claimed in claim 1, wherein Y is selected from the group consisting of: HNC(?O), C(?O)NH, OC(?O)NH, HNC(?O)O, R.sup.4NC(?O)NR.sup.4, R.sup.4NC(?NR.sup.4)NR.sup.4, and R.sup.4NC(?S)NR.sup.4.

5. The silane as claimed in claim 1, wherein the radicals R are linear or branched alkylene radicals having 1 to 20 carbon atoms, or cycloalkyl groups having 4 to 8 carbon atoms.

6. The silane as claimed in claim 1, wherein the radicals R.sup.7 are aromatic groups A.

7. The silane as claimed in claim 1, wherein A is selected from the group consisting of phenylene, naphthylene, pyridyl, pyridazyl, pyrimidyl, pyrazyl, triazyl, quinolyl, pyrrolyl, furanyl, thiophenyl, pyrazolyl, imidazolyl, thiazolyl and oxazolyl radicals, and derivatives of the groups thereof.

8. The silane as claimed in claim 1 having formula II): ##STR00012##

9. The silane as claimed in claim 1 having formula III): ##STR00013##

10. The silane as claimed in claim 1, wherein the radicals R.sup.7 are a linear alkylene radical.

11. The silane as claimed in claim 1, wherein the radicals R are a linear alkylene radical, and G is an alkanoyl group.

12. The silane as claimed in claim 1 having formula VIII): ##STR00014##

13. The silane as claimed in claim 1 further comprised on the surface of silica.

14. The silane as claimed in claim 13 further comprised in a rubber mixture.

15. The silane as claimed in claim 14 further comprised in at least one component of a vehicle tire.

Description

(1) The invention shall be explained in more detail hereinbelow with reference to exemplary embodiments.

(2) The silane of formula III), as an example according to the invention, was prepared in the following way:

1. Preparation of 1-(4-Aminophenyl)-3-(3-(Triethoxysilyl)Propyl)Urea According to the Synthesis Scheme of Formula IV)

(3) ##STR00004##
3-(Isocyanatopropyl)triethoxysilane (11.44 ml, 11.44 g, 46.2 mmol, 1.0 eq.) was added dropwise at room temperature (RT) to a solution of para-phenylenediamine (10.00 g, 92.5 mmol, 2.0 eq.) in dichloromethane (300 ml of DCM). After stirring overnight, the solvent was removed on a rotary evaporator, affording a gray solid (21.57 g) as the crude product.

(4) Purification by column chromatography was performed in a plurality of small portions of approx. 3-4 g each (approx. 74% by weight yield in each case) on silica gel (DCM/ethanol 9:1).

(5) After drying under high vacuum, the target compound was isolated in the form of a light gray solid (extrapolated for the total product: 15.96 g, 44.9 mmol, 97% based on silane).

(6) .sup.1H NMR (nuclear magnetic resonance) (500 MHz, DMSO-d.sub.6) ? 7.82 (s, 1H), 6.98 (d, J=8.7 Hz, 2H), 6.45 (d, J=8.7 Hz, 2H), 5.91 (t, J=5.8 Hz, 1H), 4.66 (s, 2H), 3.74 (q, J=7.0 Hz, 6H), 3.00 (q, J=6.8 Hz, 2H), 1.48-1.39 (m, 2H), 1.14 (t, J=7.0 Hz, 9H), 0.57-0.49 (m, 2H).

(7) .sup.13C NMR (126 MHz, DMSO-d.sub.6) ? 155.69, 143.33, 129.62, 120.22, 114.12, 57.70, 41.81, 23.49, 18.24, 7.25.

2. Preparation of 4-(Octanoylthio)Benzoic Acid According to the Synthesis Scheme of Formula V)

(8) ##STR00005##

(9) Octanoyl chloride (1.7 ml, 1.63 g, 10.0 mmol, 1.0 eq.) was added dropwise at RT to a solution of 4-mercaptobenzoic acid (1.54 g, 10.0 mmol, 1.0 eq.) and pyridine (5.0 ml, 4.91 g, 62.1 mmol, 6.2 eq.) in THF (15 ml; tetrahydrofuran).

(10) The resulting suspension was stirred overnight at RT and subsequently poured onto ice in order to remove the pyridinium salt and precipitate out the target molecule. The reaction mixture was stirred for 30 min.

(11) The resulting light brown precipitate was filtered off using a Buchner funnel and washed with cold demineralized water (2?50 ml).

(12) After drying under high vacuum, the target compound was isolated in the form of a light brown powder (1.38 g, 4.9 mmol, 49%).

(13) Melting point: 170? C.

(14) .sup.1H NMR (500 MHz, DMSO-d.sub.6) ? 14.10 (s, 1H), 8.89 (d, J=8.0 Hz, 2H), 8.44 (d, J=7.9 Hz, 2H), 3.62 (t, J=7.4 Hz, 2H), 2.04-2.27 (m, 8H), 1.75 (t, J=6.6 Hz, 3H).

(15) .sup.13C NMR (126 MHz, DMSO-d.sub.6) ? 195.88, 166.77, 134.24, 132.90, 131.47, 129.95, 43.30, 31.12, 28.38, 28.21, 25.00, 22.09, 13.99.

(16) ESI-MS (electrospray ionization mass spectrometry) m/z (%): 281.12 [M+H].sup.+ (100), 303.10 [M+Na].sup.+ (73), 583.21 [2M+Na].sup.+ (59).

3. Preparation of 4-(Octanoylthio)Benzoyl Chloride (In Situ) According to the Synthesis Scheme of Formula VI)

(17) ##STR00006##

(18) DMF (0.1 ml, 1.3 mmol) was added to a suspension of 4-(octanoylthio)benzoic acid (0.84 g, 3.0 mmol, 1.0 eq.) in THF (20 ml). Oxalyl chloride (1.3 ml, 1.91 g, 15.0 mmol, 5.0 eq.) was added dropwise to the reaction mixture at 0? C. and the mixture was stirred for 30 min at this temperature.

(19) The resulting yellow solution was then stirred for a further 3 h at RT. Thereafter, the solvent and excess oxalyl chloride were removed by means of a high vacuum and cold trap.

(20) A yellow solid was isolated that was used for the next synthesis step without further analysis or purification (on account of its reactivity).

4. Preparation of the Silane of Formula Iii) According to the Synthesis Scheme of Formula VII)

(21) ##STR00007##

(22) A solution of 4-(octanoylthio)benzoyl chloride (0.90 g, 3.0 mmol, 1.0 eq.) in THF (10 ml) was added dropwise at RT, over a period of 15 min, to a solution of 1-(4-aminophenyl)-3-(3-(triethoxysilyl)propyl)urea (1.07 g, 3.0 mmol, 1.0 eq.) and triethylamine (2.1 ml, 1.52 g, 15.0 mmol, 5.0 eq.) in THF (10 ml).

(23) The resulting white suspension was stirred overnight at RT and then filtered off using a Buchner funnel. The filter cake was washed with cold THF (2?50 ml) and demineralized water (4?50 ml). The powder obtained after drying was resuspended in water for 30 min in order to remove ammonium salts still present.

(24) After drying under high vacuum, the target compound was isolated in the form of a white powder (1.45 g, 2.3 mmol, 78% yield).

(25) Melting point: 158? C.

(26) .sup.1H NMR (500 MHz, DMSO-d.sub.6) ? 10.23 (s, 1H), 8.37 (s, 1H), 7.95-8.02 (m, 2H), 7.58-7.64 (m, 2H), 7.52-7.57 (m, 2H), 7.33-7.39 (m, 2H), 6.14 (t, J=5.7 Hz, 1H), 3.75 (q, J=7.0 Hz, 6H), 3.05 (q, J=6.6 Hz, 2H), 2.74 (t, J=7.4 Hz, 2H), 1.57-1.65 (m, 2H), 1.48 (ddd, J=10.8, 5.2, 2.8 Hz, 2H), 1.21-1.34 (m, 8H), 1.15 (t, J=7.0 Hz, 9H), 0.83-0.89 (m, 3H), 0.51-0.59 (m, 2H).

(27) .sup.13C NMR (126 MHz, DMSO-d.sub.6) ? 196.18, 164.35, 155.23, 136.76, 135.86, 134.14, 132.48, 131.01, 128.37, 121.08, 117.73, 57.75, 43.26, 41.80, 31.12, 28.38, 28.22, 25.02, 23.42, 22.09, 18.28, 13.99, 7.29.

(28) .sup.29Si NMR (99 MHz, DMSO-d.sub.6) ? ?44.56.

(29) ESI-MS m/z (%): 618.30 [M+H].sup.+ (100), 640.28 [M+Na].sup.+ (18).

(30) The silane of formula VIII), as a further example according to the invention, is prepared for example in the following way:

1. Preparation of 3-(Acetylthio)Propionic Acid According to the Synthesis Scheme of Formula IX)

(31) ##STR00008##

(32) This introduces a thioacetyl group by nucleophilic substitution of 3-chloropropionic acid with potassium thioacetate (KSAc) and DMF (dimethylformamide) as solvent.

2. Preparation of 3-(Acetylthio)Propionyl Chloride (In Situ) According to the Synthesis Scheme of Formula X)

(33) ##STR00009##

(34) This activates the acid functionality with oxalyl chloride (COCl).sub.2 and catalytic amounts of DMF in THF as solvent.

3. Preparation of 1-(4-Aminophenyl)-3-(3-(Triethoxysilyl)Propyl)Urea According to the Synthesis Scheme of Formula XI)

(35) ##STR00010##

(36) This forms the urea by reaction of para-phenylenediamine and one equivalent of 3-(isocyanatopropyl)triethoxysilane in DCM (dichloromethane) as solvent.

4. Preparation of the Silane Of Formula Viii) According to the Synthesis Scheme of Formula XII)

(37) ##STR00011##

(38) This forms the amide by reaction of 3-(acetylthio)propionyl chloride with 1-(4-aminophenyl)-3-(3-triethoxysilyl)propyl)urea in the presence of triethylamine as auxiliary base and THF as solvent.

(39) The silane of formula VIII) can also be prepared by starting from 3-chloropropionyl chloride and converting it to the amide with 1-(4-aminophenyl)-3-(3-triethoxysilyl)propyl)urea and only then introducing the thioacetyl group by nucleophilic substitution of the chloride (with potassium thioacetate).

(40) The prepared silane of formula III) and/or VIII) is mixed into a rubber mixture according to the invention containing at least one diene rubber and at least one silica as filler. To this end, the silane of formula III) and/or VIII) is preferably adsorbed onto a silica beforehand and subsequently added in this form to the rubber mixture.

(41) Adsorption onto silica is carried out, for example, as follows:

(42) To a suspension of silica, for example granulated silica, in DMF is added, at room temperature, a solution of the silane of formula III) and/or VIII) dissolved in DMF in the desired silica/silane ratio. For example, 30.0 g of silica (VN3, Evonik) and 4.43 g of the silane of formula III) or 3.32 g of the silane of formula VIII) are used.

(43) The resulting suspension is for example stirred overnight at 120? C. and the solvent is subsequently removed under reduced pressure. After drying for one day under high vacuum at 40? C., the modified silica thus obtained is comminuted by means of a mortar possibly according to the fineness desired. It is then for example dried under high vacuum for a further day at 40? C.

(44) The rubber mixture according to the invention is by way of example applied in the form of a preformed tread of a vehicle tire (as described above) to a green tire and subsequently vulcanized with the latter.