Title of Invention

"AN ORGANOSILICON COMPOUND AND THE PROCESS FOR PREPARING THE SAME"

Abstract The invention provides organosilicon compounds of the general formula I R1R2R3Si-R4-S-Zn-S-R4-SiR1R2R3 (I) wherein R1, R2, R3 independently, represent H, a halogen, alkyl or alkoxy and R4 represents an alkylidene group, their preparation and their use in rubber mixtures.
Full Text -1A-
Description
The present invention provides an organosilicon compound, a process for its preparation and its use.
It is known that sulfur-containing organosilicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercapto-propyltriethoxysilane, 3-thiocyanatopropyltriethoxysilane or bis-(3-[triethoxysilyl]-propyl)tetrasulfane are used as silane bonding agents or reinforcing additives in oxidically filled rubber mixtures. The rubber mixtures are used, inter alia, for industrial rubber items and for parts of rubber types, in particular for treads (IN 140550,
IN 140550, IN 140550).
It is also known that the alkoxysilyl function, generally a trimethoxysilyl or triethoxysilyl group, reacts with silanol groups on the fillers, generally silica, during mixing-preparation and thus the silane becomes fixed onto the surface of the filler. Production of the filler/rubber bond then takes place during the vulcanisation process, via the sulfur groupings on the fixed silane. Accordingly, the resulting properties of this type of vulcanisate, for a given constant amount of silane, depends critically on how high the coupling yield of the silane is and what network structure is produced. Furthermore, it is known that silanes with polysulfane functions such as, for example, bis-(3-[triethoxysilyl]-propyl)tetrasulfane, tend to participate in disadvantageous premature cross-linking during the mixing process, at appropriately high temperatures. Therefore, it is important that a maximum batch temperature of about 155°C is not exceeded when using these silanes.
The object of the present invention is to provide organosilicon compounds which have higher coupling yields.

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improved rubber properties and higher process reliability than the silanes known hitherto, when used as a bonding agent or reinforcing additive in rubber mixtures.
The invention provides an organosilicon compound of the general formula I
R1R2R3Si-R4-S-Zn-S-R4-SiR1R2R3 (I)
wherein R1, R2, R3, independently, represent H, a halogen, a straight-chain or branched alkyl group or a straight-chain or branched alkoxy group and R4 represents a straight-chain or branched alkylidene group.
The straight-chain alkyl groups may be methyl, ethyl, n-propyl, n-butyl-, n-pentyl- or n-hexyl groups. The branched alkyl groups may be iso-propyl, iso-butyl or tert-butyl groups. The halogen may be fluorine, chlorine, bromine or iodine. The alkoxy groups may be methoxy, ethoxy, propoxy, butoxy, isopropoxy, isobutoxy or pentoxy groups.
In the organosilicon compound in accordance with formula I, R1, R2, R3 preferably represent ethoxy and R4 preferably represents CH2CH2CH2 or isobutylidene.
The invention also provides a process for preparing the organosilicon compound of the general formula I, characterised in that a mercaptan compound of the general formula II
R1R2R3Si-R4-S-H (II)
wherein R1, R2, R3, independently, represent H, a halogen, a straight-chain or branched alkyl group or a straight-chain or branched alkoxy group and R4 represents a straight-chain or branched alkylidene group.

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is reacted with a zinc alcoholate. The reaction may be performed in alcoholic solution. The reaction may be performed in a temperature range of 20° to 200°C, preferably 50° to 80°C.
Zinc ethanolate may be used as the zinc alcoholate. Ethanol may be used to prepare the alcoholic solution. The zinc alcoholate may be prepared by reacting zinc chloride with sodium ethanolate in alcoholic solution. The zinc alcoholate may be reacted with double the molar amount of mercaptan compound II in alcoholic solution.
3-mercaptopropyltriethoxysilane may be used as a mercaptan compound. In one embodiment, a compound of the formula II with R1, R2, R3 = ethoxy and R4 = CH2CH2CH2, may be reacted with zinc ethanolate in ethanolic solution.
The organosilicon compound according to the invention is highly reactive and may be used in rubber mixtures.
Rubber mixtures which contain the organosilicon compound according to the invention as a bonding agent or as a reinforcing additive and the moulded items which are produced after a vulcanisation step, in particular pneumatic tyres or tyre treads, have a low rolling resistance with a simultaneously good wet adhesion and a high resistance to abrasion.
The invention also provides rubber mixtures, characterised in that they contain rubber, fillers, preferably precipitated silica, at least one organosilicon compound of the formula (I) and optionally other rubber auxiliary substances.
The organosilicon compound of the formula I may be used in amounts of 0.1 to 15 wt.%, preferably 5-10 wt.%, with respect to the amount of filler used.
Natural rubber and/or synthetic rubber may be used as the rubber. Preferred synthetic rubbers are described, for

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example, in W. Hofmann, Kautschuktechnologie, Center Verlag, Stuttgart 1980. The rubbers may be used individually or else in combination. Anionic polymerised S-SBR rubbers with a glass transition temperature above -50°C and its mixtures with high-cis diene rubbers are used in particular for preparing motor vehicle tyres.
The following may be used as fillers:
carbon blacks, which are prepared by the lamp, furnace or channel process and have a BET surface area of 20 to 200 m2/g,
highly disperse silicas prepared, for example, by precipitation from silicate solutions or by flame hydrolysis from silicon halides, with specific surface areas of 5 to 1000 mVg, preferably 20 to 400 m2/g (BET surface area) and with primary particle sizes of 10 to 4 00 nm, optionally also as mixed oxides with other metal oxides such as Al, Mg, Ca, Ba, Zn and titanium oxides,
synthetic silicates such as aluminium silicate, alkaline earth silicates such as, for example, magnesium silicate or calcium silicate, with BET surface areas of 20 to 400 m2/g and primary particle diameters of 10 to 400 nm,
natural silicates such as kaolin and other naturally occurring silicas,
glass fibres and glass fibre products (mats, ropes) or glass microbeads.
The rubber mixtures may contain synthetic rubber and silica as a filler. Highly disperse silicas, prepared by precipitation from silicate solutions, with BET surface areas of 20 to 400 m2/g are preferably used, in amounts of 10 to 150 parts by weight, with respect to 100 parts by weight of rubber.

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The fillers mentioned may be used individually or as a mixture.
In a particularly preferred embodiment of the rubber mixture, 10 to 150 parts by weight of a pale filler, optionally together with 0 to 100 parts by weight of carbon black, with respect to 100 parts by weight of rubber, and 0.1 to 15 parts by weight, preferably 5 to 10 parts by weight of a compound of the formula (I), with respect to 100 parts by weight of the filler used, may be used to prepare the mixtures.
The organosilicon compounds according to the invention may be used either in the pure form or attached to an inert organic or inorganic support. Preferred support materials may be silica, natural or synthetic silicates, aluminium oxide or carbon black. The organosilicon compound according to the invention may be used on its own or combined with other organosilicon compounds, in particular monofunctional alkylalkoxysilanes.
Rubber auxiliary products which may be used are reaction accelerators, reaction delayers, antioxidants, stabilisers, processing aids, plasticisers, waxes, metal oxides and activators such as triethanolamine, polyethylene glycol or hexanetriol which are well-known in the rubber industry.
The rubber auxiliary substances may be used in conventional amounts which are governed, inter alia, by the ultimate application. Conventional amounts may be 0.1 to 50 wt.%, with respect to rubber. The organosilicon compounds may be activated by adding sulfur and accelerators before the actual cross-linking reaction. This activation may take place during the vulcanisation step. Suitable vulcanisation accelerators may be mercaptobenzthiazoles, sulfenamides, guanidines, thiurams, dithiocarbamates, thioureas and thiocarbonates. The vulcanisation accelerator and sulfur or peroxides may be

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used in amounts of 0.1 to 10 wt.%, preferably 0.1 to 5 wt.%, with respect to rubber.
Use of organosilicon compounds according to the invention in rubber mixtures results in advantages in the static and dynamic vulcanisate data as compared with mixtures according to the prior art. This is shown in particular by a higher tensile strength, a higher 300% stress modulus, and an improved 300% / 100% stress modulus reinforcing ratio. In addition, mixtures according to the invention exhibit a decreased build-up of heat (Goodrich flexometer test), which indicates a positive hysteresis behaviour, and an advantageously low loss factor tan d (60°C), which correlates with the rolling resistance value.
The invention also provides a process for preparing rubber mixtures, characterised in that rubber is mixed with fillers, at least one organosilicon compound of the formula I and optionally other rubber auxiliary substances.
The organosilicon compounds according to the invention and the fillers may preferably be incorporated at bulk temperatures of 100 to 200°C, but may also be incorporated later at lower temperatures (40 to 100°C), for example together with other rubber auxiliary substances. Mixing the constituents may be performed in conventional mixing equipment such as rollers, internal mixers and mixer extruders.
Vulcanisation of rubber mixtures according to the invention may take place at temperatures of 100 to 200°C, preferably 130 to 180°C, and optionally under a pressure of 10 to 200 bar. Rubber vulcanisates according to the invention may be moulded items, for example pneumatic tyres, tyre treads, cable sheathing, hoses, drive belts, conveyer belts, roller coverings, tyres, soles of shoes, sealing rings and damping elements.

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The use of organosilicon compounds according to the invention as bonding agents or reinforcing additives in rubber mixtures leads to much higher coupling yields, and a correspondingly improved set of rubber properties, than known silanes. Organosilicon compounds according to the invention do not exhibit the known tendency to premature cross-linking of the unaccelerated mixture at high mixing temperatures. Thus, much higher processing temperatures can be tolerated with greater process reliability. Activation of the sulfur-functional group can take place only during vulcanisation with the addition of sulfur and accelerator.

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Examples
Example 1: Preparing the zinc organosilicon compound
Example 1 describes preparation pf an organosilicon compound in accordance with the invention.
To prepare a sodium ethanolate solution, 750 ml of ethanol is initially introduced into a11 flask under an atmosphere of argon and then pieces of sodium (46 g, 2 mol) are added in portions.
To prepare the zinc organosilicon compound, 7 50 ml of ethanol and 136.3 g (1 mol) of zinc chloride are initially introduced into a 4 1 four-necked flask with a stirrer, condenser, thermometer and dropping funnel. The freshly prepared sodium ethanolate solution is then transferred to the dropping funnel and added dropwise over a period of
1 hour with stirring and heating to 78°C. The mixture is allowed to stand overnight in order to complete post-reaction and then 446.8 g (2 mol) of 3-mercaptopropyl-triethoxysilane are added dropwise over the course of
2 hours with heating. Stirring is continued for a further 4 hours at 78°C and the mixture is then cooled to room temperature, the suspension is filtered and washed 3 times with 100 ml of ethanol. The filtrate is evaporated down to dryness and the remaining solid is dried under vacuum at 120°C and then milled.
514.8 g of solid product are obtained, which corresponds to 95.5% of theoretical.
Elemental analysis: C: 38.66%, calc. 40.02%
H: 7.64%, calc. 7.84% S: 11.92%, calc. 11.87% Cl:
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Examples 2-5: Preparing the rubber mixtures and vulcanisates
In examples 2 to 5, the preparation of rubber mixtures and vulcanisates is described. On the basis of example 5, which contains the organosilicon compound according to the invention from example 1 as bonding agent, the superior properties of compounds according to the invention, as compared with the prior art (examples 2 to 4) are clear.
General methods used
The formulation used for the rubber mixtures is given in table 1 below. The units phr represent the proportion by weight with respect to 100 parts of crude rubber used.
Table 1

Substance Amount [phr]
1st stage
Buna VSL 5025-1 96.0
Buna CB 24 30.0
Ultrasil 7000 GR 80.0
ZnO 3.0
Stearic acid 2.0
Naftolen ZD 10.0
Vulkanox 4020 1.5
Protector G35P 1.0
Silane as stated in
the example
2nd stage
Batch from stage 1
3rd stage
Batch from stage 2
Vulkacit D 2.0
Vulkacit CZ 1.5
Sulfur as stated in
The example
The polymer VSL 5025-1 is a SBR copolymer from Bayer AG, polymerised in solution, with a styrene content of 25 wt.%

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and a butadiene content of 75 wt.%. 73% of the butadiene is 1,2 linked, 10% is cis-1,4 and 17% is trans-1,4 linked. The copolymer contains 37.5 phr of oil and has a Mooney viscosity (ML 1+4/100°C) of about 50.
The polymer Buna CB 24 is a cis-1,4-polybutadiene (Neodyme type) from Bayer AG, with a cis-1,4 content of 97%, a trans-1,4 content of 2%, a 1,2 content of 1% and a Mooney viscosity between 4 4 and 50 ME.
Ultrasil 7000 GR is a readily dispersible silica from Degussa-Huls AG and has a BET surface area of 175 m2/g.
The silane with the tradename Si 69 is bis-(3-[triethoxy-silyl]-propyl)tetrasulfane, the silane Si 264 is 3-thio-cyanatopropyltriethoxysilane and Dynasilan 3201 is 3-mercaptopropyltriethoxysilane. The silanes mentioned above are sold by Degussa-Huls AG.
Naftolen ZD from Chemetall is used as an aromatic oil, Vulkanox 4020 is PPD from Bayer AG and protector G35P is an anti-ozonant wax from HB-Fuller GmbH. Vulkacit D (DPG) and Vulkacit CZ (CBS) are commercial products from Bayer AG.
The rubber mixture is prepared in three stages, using an internal mixer, in accordance with table 2.

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Table 2:

Stage 1
Settings
Mixing unit Werner & Pfleiderer
Friction 1:1.11
Speed 70 min-1
Internal 5.5 bar
pressure
Empty volume 1.6 1
Extent filled 0.55
Flow-through 70°C
temp.
Mixing process
0 to 1 min Buna VSL 5025-1 + Buna CB 24
1 to 3 min ½ Ultrasil 7000 GR, ZnO, Stearic acid Naftol-en ZD, silane
3 to 4 min ½ Ultrasil 7000 GR, Vulkanox 4020, Protector G35P
4 min Clean
4 to 5 min Mix
5 min Clean
5 to 6 min mix and discharge
Batch temp. 140-150°C
Storage 24 h at room temperature

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Stage 2
Settings
Mixing unit same as stage 1 down to:
Speed 80 min-1
Extent filled 0.53
Flow-thru temp. 80°C
Mixing process
0 to 2 min Break up batch from stage 1
2 to 5 min Batch temperature 150°C maintained varying the speed by
5 min Discharge
Batch temp. 150-155°C
Storage 4 h at room temperature

Stage 3
Settings
Mixing unit same as in stage 1 down to
Speed 40 min-1
Extent filled 0.51
Flow-thru temp. 50°C
Mixing process
0 to 2 min Batch from stage 2 + Vulkacit CZ + Vulkazit D + sulfur
2 min discharge and form a sheet on a laboratory mixing roller unit
(diameter 200 mm, length 4 50 mm,
flow-through temperature 50°C)
Homogenise:
3* to the left, 3* to the right cut into and fold over and also pass through
8* with a narrow roller gap (1 mm) and
3* with a wide roller gap (3.5 mm) then draw out into a sheet and
Batch temp. 90-100°C

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The general method for preparing rubber mixtures and their vulcanisates is described in "Rubber Technology Handbook", W. Hofmann, Hanser Verlag 1994.
Rubber engineering tests were performed in accordance with the test methods cited in table 3.
Table 3

Physical tests Standard/ Conditions
ML 1+4, 100°C (3rd stage) DIN 53523/3, ISO 667
Vulcameter test, 165°C DIN 53529/3, ISO 6502
Tensile test on a ring, 23°C DIN 53504, ISO 37
Tensile strength
Modulus
Extension at break
Shore-A hardness, 23°C DIN 53 505
Ball rebound, 23°C ASTM D 5308
Viscoelastic properties, . DIN 53 513,
0 and 60°C, 16 Hz, 50 N initial ISO 2856
force and 25 N amplitude force
Complex Modulus E*,
Loss factor tan 6
Goodrich Flexometer test, DIN 53 533
0.25 inch, 25 min, 23°C start ASTM D 623-A
Contact temperature
Centre temperature
Permanent set
DIN-abrasion, 10 N force DIN 53 516
Dispersion ISO/DIN 11345
Examples 2 to 5:
Examples 2 to 5 were performed in accordance, with "General methods used", wherein examples 2 to 4 are described as comparison examples from the prior art.
6.40 phr Si 69 and 1.5 phr sulfur were used in example 2, 6.32 phr Si 264 and 2.2 phr sulfur were used in example 3 and 5.75 phr Dynasilan 3201 and 2.2 phr sulfur were used

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in example 4, 6.47 phr of the organosilicon compound according to the invention from example 1 and 2.2 phr sulfur were used in example 5. This corresponds to equimolar addition with a sulfur content adjusted in accordance with one of the silanes.
Table 4 gives the rubber engineering data for the crude mixture and the vulcanisete.
Table 4:

Crude mixture results
Feature Units ex. 2 ex. 3 ex. 4 ex. 5
ML(1+4)at 100°C [ME] 58 57 63 63
Dmax-Dmin [dNm] 16.5 16.0 10.6 10.7
t 10% [min] 1.8 1.1 0.5 0.5
t 90% [min] 26.8 25.1 26.2 27.4
t 80% -1 20% [min] 10.2 8.2 9.9 10.4
Vulcanisation time [min] 50 50 40 50

Vulcanisate results
Feature Units ex. 2 ex. 3 ex. 4 ex. 5
Tensile strength [MPa] 14.4 13.7 13.4 13.0
Modulus 100% [MPa] 1.6 1.8 1.6 1.5
Modulus 300% [MPa] 8.2 10.0 9.3 9.5
Modulus 300/100% [-] 5.2 5.4 5.8 6.4
Extension at break [%] 420 360 360 350
Fracture energy [J] 81.3 64.6 58.0 52.7
Shore-A hardness [SH] 63 63 55 55
Bali rebound (23°C) [%] 32.9 34.1 38.3 36.5
DIN-abrasion [mm3] 89 75 58 65
Dyn. exp. modulus E* (OX) [MPa] 19.9 20.5 12.7 14.8
Dyn. exp. modulus E* (60°C) [MPa] 8.3 8.8 6.2 7.1
Loss factor tan 6 (0°C) H 0.505 0.482 0.454 0.473
Loss factor tan 5 (60°C) [-] 0.114 0.104 0.099 0.090
Contact temperature [°C] 67 68 62 61
Insertion temperature [°c] 118 118 113 112
Permanent set [%] 5.0 3.8 3.3 2.8
Dispersion Phillips [-] 8 9 7 9
The mixture from example 5 with the organosilicon compound according to the invention from example 1 shows, as

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compared with the reference mixtures, a very good set of static properties. In particular, the 300%/100% modulus reinforcement factor is significantly higher than the reference mixtures, which indicates a high yield of filler-rubber bonds. In addition, the loss factor tan 5 (60°C), which correlates with the rolling resistance, is advantageously low. Furthermore, the build-up of heat by the mixture in the Goodrich Flexometer test is lowest for the mixture from example 5.
In addition, the advantageous, high, thermal stability of the silane according to the invention is very obvious. Thus, there is hardly any increase in torque detected in the unaccelerated mixture at 165°C (Figure 1). This shows that the unaccelerated mixture with the silane according to the invention is much less sensitive to scorching during the mixing process than, for example, Si 69.

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WE CLAIM:
1. An organosilicon compound of the general formula I
R1R2R3Si-R4-S-Zn-S-R4-SiR1R2R3 (I)
wherein R1, R3, R4, independently, represent H, a
halogen, a straight-chain or branched alkyl group or a straight-chain or branched alkoxy group and R4 represents a straight-chain or branched alkylidene group.
2. urganosilicon compounds as claimed in Claim 1,
wherein
R1, R3, R3 = ethoxy and R4 - CH2CH2CH2 or isobutylidene.
3. A process for preparing organosilicon compounds
as claimed in Claim 1,
wherein a mercaptan compound of the general formula II
R1R2R3Si-R4-S-H (II),
wherein R1, R3, R3, independently, represent H, a
halogen, a straight-chain or branched alkyl group or a straight-chain or branched alkoxy group and
R4 represents a straight-chain or branched alkylidene group,
is reacted with zinc alcoholate.
4. A process,for preparing organosilicon compounds
as claimed in Claim 3,
wherein
the reaction is performed in the temperature range 20° to 200°C.

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5. A process for preparing organositicon compounds as claimed in claim 3, wherein the reaction is performed in alcoholic solution.
6. A process for preparing organosilicon compounds as claimed In claim 3, wherein a compound of the formula II with R1 R2, R3 = ethoxy, R4 = CH2CH2CH2, is reacted with zinc ethanolate in ethanoiic solution.
7. Rubber mixtures, wherein they contain rubber, filler at least one organosilicon compound of the formula I and optionally other rubber auxiliary substances.
8. Rubber mixtures as claimed in claim 7, wherein the organosilicon compound of the formula I is used in an amount of 0.1 to 15 wt.%, with respect to the amount of filler used.
9. Rubber mixtures as claimed in claim 7. wherein they contain synthetic rubber and silica as filler.
10. A process for preparing rubber mixtures as claimed in claim 7, wherein
rubber, filler, at least one organosilicon compound of the formula I and
optionally other rubber auxiliary substances are mixed.
The invention provides organosilicon compounds of the general formula I
R1R2R3Si-R4-S-Zn-S-R4-SiR1R2R3 (I)
wherein R1, R2, R3 independently, represent H, a halogen, alkyl or alkoxy and R4 represents an alkylidene group,
their preparation and their use in rubber mixtures.

Documents:

00583-cal-2000 abstract.pdf

00583-cal-2000 claims.pdf

00583-cal-2000 correspondence.pdf

00583-cal-2000 description(complete).pdf

00583-cal-2000 drawings.pdf

00583-cal-2000 form-1.pdf

00583-cal-2000 form-18.pdf

00583-cal-2000 form-2.pdf

00583-cal-2000 form-3.pdf

00583-cal-2000 form-5.pdf

00583-cal-2000 g.p.a.pdf

00583-cal-2000 letters patent.pdf

00583-cal-2000 priority document others.pdf

00583-cal-2000 priority document.pdf

00583-cal-2000 reply f.e.r.pdf


Patent Number 207101
Indian Patent Application Number 583/CAL/2000
PG Journal Number 21/2007
Publication Date 25-May-2007
Grant Date 23-May-2007
Date of Filing 16-Oct-2000
Name of Patentee DEGUSSA AG..,
Applicant Address BENNIGSENPLATZ 1,D-40474 DUSSELDORF,
Inventors:
# Inventor's Name Inventor's Address
1 LUG INSLAND HANS-DETLEF RADERBERGER STRASSE 147, D-50968 KOLN;
2 BATZ-SOHN CHRISTOPH MOZARTSTRASSE 1,D-63452 HANAU;
3 MUNZENBERG JORG, FORSTHAUSTRASSE 11,D-63457 HANAU;
4 ZEZULKA GEARD RAINHARD AN DER MAINBRUICKE 19,D-63456 HANAU;
PCT International Classification Number C07F 3/06
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 19950608 1999-10-21 Germany