Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-03-26
2001-06-26
Mulcahy, Peter D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S387000, C524S388000
Reexamination Certificate
active
06251976
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to rubber mixtures consisting of at least one rubber and a specific proportion of a distillation residue from industrial trimethylolpropane production, and to the use of the rubber mixtures for the production of vulcanisates, especially for the production of highly reinforced, abrasion-resistant mouldings, particularly preferably for the production of tyres exhibiting low rolling resistance and high abrasion resistance.
BACKGROUND OF THE INVENTION
To produce tyres with reduced rolling resistance, a number of proposed solutions have been worked out. In DE-A 2 255 577 and 4 435 311, EP-A 670 347 and U.S. Pat. No. 4,709,065, specific polysulfidic silanes have been described as reinforcing fillers for silica-containing rubber vulcanisates. A disadvantage of the use of the polysulfidic silanes described there as reinforcing fillers for silica-containing rubber vulcanisates, however, is that relatively large quantities of the expensive polysulfidic silanes are needed to achieve acceptable processing properties.
To improve the processing properties of silica-containing rubber mixtures, other additives such as fatty acid esters, fatty acid salts or mineral oils have been proposed. However, these additives have the disadvantage of increasing flowability but, at the same time, reducing the moduli at greater elongation (e.g. 100 to 300%), so that the reinforcing effect of the filler is reduced.
In addition, it was known to add polyalcohols and polyglycols to rubber mixtures to improve their processing properties (cf. EP-A 761 734 and EP-A 738 755). Compared with the distillation residues from industrial trimethylolpropane production according to the invention, however, polyalcohols and polyglycols are expensive and inadequate in terms of improving flowability and scorch time.
SUMMARY OF THE INVENTION
The object of the present invention was therefore to find less expensive additives which greatly increase the flowability of rubber mixtures and increase the scorch time without exhibiting the disadvantages of the additives used up to the present, as described above.
DETAILED DESCRIPTION OF THE INVENTION
The present invention therefore provides rubber mixtures consisting of at least one rubber and 0.1 to 15 parts by weight, based on 100 parts by weight of the total quantity of rubbers used, of a distillation residue from industrial trimethylolpropane production, the distillation residue having a viscosity of 0.5 to 20 Pa.sec at 100° C.
A quantity of 0.3 to 10 parts by weight of a trimethylolpropane distillation residue is preferably added to the rubber mixtures according to the invention, particularly preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the total quantity of rubbers used.
The viscosity of the distillation residue from industrial trimethylolpropane production is preferably 0.5 to 10 Pa.sec at 100° C.
Trimethylolpropane (2-ethyl-2-(hydroxymethyl)-1,3-propanediol) is obtained industrially by aldol condensation and reduction of n-butyraldehyde with formaldehyde, in yields of approx. 90%. Milk of lime, alkali or basic ion exchangers are generally used as catalysts for aldol condensation. Excess formaldehyde and bases, such as e.g). sodium hydroxide solution, reduce the aldol formed to trimethylolpropane. The reaction mixture is worked up by extraction with solvents such as amyl alcohol, cyclohexanol or acetic ester and subsequent distillation of the trimethylolpropane. In connection with this, we refer to Ullmann, Verlag Chemie, Weinheim 1976 (4) 7, page 231 and to the literature cited there. The residue remaining after distillation of the trimethylolpropane has the viscosity stated above and generally contains less than 10 wt. %, preferably less than 5 wt. % trimethylolpropane.
The rubbers to be used for the production of the rubber mixtures according to the invention include natural rubber and synthetic rubbers. Preferred synthetic rubbers are described, for example, in W. Hofmann, Kautschuktechnologie, Genter Verlag, Stuttgart 1980. They include
BR—polybutadiene
ABR—butadiene/ C
1
-C
4
alkyl acrylate copolymers
CR—polychloroprene
IR—polyisoprene
SBR—styrene/butadiene copolymers with styrene contents of 1-60, preferably 20-50 wt. %.
IIR—isobutylene/isoprene copolymers
NBR—butadiene/acrylonitrile copolymers with acrylonitrile contents of 5-60, preferably 10-40 wt. %
HNBR—partially hydrated or fully hydrated NBR rubber
EPDM—ethylene/propylene/diene copolymers
and mixtures of these rubbers.
For the production of vehicle tyres, mixtures of natural rubber, emulsion SBR and solution SBR and polybutadiene rubber are especially important. The use of solution SBR rubbers with a vinyl content of 20-60 wt. % and of polybutadiene rubbers with a high 1,4-cis content (>90%) produced with catalysts based on nickel, cobalt, titanium and/or neodymium, and polybutadiene rubber with a vinyl content of up to 75% and mixtures of these solution SBR and polybutadiene rubbers is of particular interest for use in the rubber mixtures according to the invention.
The rubber mixtures according to the invention may contain 0.1 to 300 parts by weight of many different fillers, based on 100 parts by weight of the total quantity of rubber. Oxide or silicate fillers, carbon blacks or rubber gels are particularly suitable as fillers. Oxide or silicate fillers are preferred.
The following are particularly preferred:
fine-particle silica, produced e.g. by precipitation of solutions of silicates or flame hydrolysis of silicates, from silicon halides with specific surfaces of 5-1000, preferably 20-400 m
2
/g (BET surface) and with a primary particle size of 10-400 nm. The silicas may optionally also be present as mixed oxides with other metal oxides, such as Al, Mg, Ca, Ba, Zn, Zr, Ti oxides.
synthetic silicates, such as aluminium silicate, alkaline earth silicates, such as magnesium silicate or calcium silicate, with BET surfaces of 20-400 m
2
/g and primary particle diameters of 10-400 nm.
natural silicates, such as kaolin and other naturally occurring silicas
glass fibres and glass-fibre products (mats, strands) or microglass beads
metal oxides, such as zinc oxide, calcium oxide, magnesium oxide, aluminium oxide
metal carbonates, such as magnesium carbonate, calcium carbonate, zinc carbonate
metal hydroxides, such as aluminium hydroxide, magnesium hydroxide.
The fillers mentioned are preferably used in quantities of 5 to 200 parts by weight, especially in quantities of 10 to 150 parts by weight, based on 100 parts by weight of rubbers used.
As mentioned, carbon blacks are also suitable as fillers. They are produced by the lamp black, furnace or gas black process and have BET surfaces of 20 to 200 m
2
/g, such as e.g. SAF, ISAF, HAF, FEF or GPF blacks.
In addition, rubber gels may also be added as fillers to the rubber mixtures according to the invention. These rubber gels are based on polybutadiene, polychloroprene, NBR or SBR rubbers.
In a particularly preferred embodiment the rubber mixtures according to the invention consist of 0.5-10 parts by weight distillation residue from industrial trimethylolpropane production, 10 to 100 parts by weight of oxide or silicate filler and 5 to 50 parts by weight of carbon black and/or rubber gels, each based on 100 parts by weight of rubbers used, in addition to at least one rubber.
To produce rubber vulcanisates, the known, conventional rubber auxiliaries may be added to the rubber mixtures according to the invention, especially vulcanisation accelerators, antioxidants, heat stabilisers, light stabilisers, ozone stabilisers, processing aids, plasticisers, tackifiers, blowing agents, dyes, pigments, waxes, extenders, organic acids, inhibitors, metal oxides, crosslinking agents and activators. In connection with this, we refer to I. Franta, Elastomers and Rubber Compounding Materials, Elsevier 1989.
The rubber auxiliaries are used in conventional quantities which depend, among other things, on the application. Conventional quantities are, e.g., quantities of 0.1-50 wt. %, based on the total quantity of
Noack Achim
Scholl Thomas
Steger Lothar
Weidenhaupt Herman-Josef
Bayer Aktiengesellschaft
Cheung Noland J.
Gil Joseph C.
Mulcahy Peter D.
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