Rubber mixtures containing 1,4-butenediol (polyether)

Details Rubber mixtures containing 1,4-butenediol (polyether) Rubber mixtures containing 1,4-butenediol (polyether)

2002-07-15

2004-11-09

Wu, David W. (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...

C524S386000, C524S380000, C524S377000, C524S378000

Reexamination Certificate

active

06815484

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to rubber mixtures that contain, in addition to at least one rubber, also 1,4-butenediol and/or 1,4-butenediol polyether as well as fillers, as well as the use of the rubber mixtures for the production of vulcanizates, in particular for the production of highly reinforced, abrasion-resistant molded articles, more preferably for the production of tires that have a low rolling resistance and a high abrasion resistance.
BACKGROUND OF THE INVENTION
A number of proposed solutions have been elaborated for producing tires having a reduced rolling resistance. Specific polysulfide silanes as reinforcing additives for silicic acid-containing rubber vulcanizates have been described in DE-A-2 255 577 and 4 435 311, EP-A1 0 670 347 as well as U.S. Pat. No. 4,709,065. However, a disadvantage of the use of the polysulfide silanes described there as reinforcing additives for silicic acid-containing rubber vulcanizates is that relatively large amounts of the expensive polysulfide silanes have to be used in order to achieve an acceptable compatibility.
In order to improve the processing of silicic acid-containing rubber mixtures, further additives have been proposed such as fatty acid esters, fatty acid salts or mineral oils. The aforementioned additives have the disadvantage that they raise the flowability but at the same time reduce the tensile modulus values at relatively large elongation (e.g. 100% to 300%), with the result that the reinforcing action of the filler is impaired.
It has also been known to add polyalcohols and polyglycols to rubber mixtures. For example, rubber mixtures that contain specific polyethylene oxides are described in EP-A1 0 869 145 and EP-A1 0 738 755. The structures of the polyethers used are not disclosed. According to the teaching of the specified documents the aforementioned polyethylene oxides scarcely improve the processability of the unvulcanized rubber mixtures, but affect in particular the properties of the vulcanizates, in particular the antistatic properties and the abrasion behavior.
Rubber mixtures containing specific 1,2-diols and 1,3-diols are known from EP-A 761 734. These rubber mixtures containing 1,2-diols and 1,3-diols tend however to stick to the roller and have an adverse effect on the mechanical properties of the vulcanizates.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention was to provide additives that, inter alia, improve the flowability of rubber mixtures without however reducing the activity of the fillers contained in the mixtures, and to provide vulcanizates having good properties, in particular with respect to abrasion, rolling resistance and wet anti-skid properties in tires.
It has now been found that 1,4-butenediol and 1,4-butenediol polyethers significantly improve the flowability of rubber mixtures and lead to vulcanizates having a good reinforcing behavior, favorable dynamic damping and good abrasion behavior.
Accordingly, the present invention provides rubber mixtures containing at least one rubber, 0.05 to 25 parts by weight with respect to 100 parts by weight of employed rubber, of 1,4-butenediol or 1,4-butenediol polyether or mixtures thereof, the butenediol polyether corresponding to the structure
wherein
R
1
and R
2
independently of one another denote hydrogen or a C
1
to C
4
alkyl radical, preferably methyl or ethyl, and
n and m independently of one another denote integers from 0 to 10, preferably 0 to 5, with the proviso that n and m cannot at the same time be 0,
as well as 1 to 500 parts by weight of filler referred to 100 parts by weight of employed rubber.
Preferably, butenediols or their polyethers are used that contain 0.1 to 10 moles of ethylene oxide and/or propylene oxide per hydroxyl group, more preferably 0.7 to 7 moles of ethylene oxide and/or propylene oxide per mole of hydroxyl groups, and that have molecular weights in the range from 88 to 1500, preferably in the range from 88 to 700. Most preferably, the corresponding polyethers are based on cis-1,4-butenediol. The production of such addition products and polyaddition products of 1,4-butenediol is known in the prior art and is described for example in Houben-Weyl, Methoden der Organischen Chemie, Vol. XIV/2, Thieme Verlag, Stuttgart, 1963 pp. 436-440 and p. 450. Such polyethers are also commercially available and, depending on their production, are preferably used as a mixture of the corresponding polyethylene oxides and polypropylene oxides. Preferably, the rubber mixtures according to the present invention contain the 1,4-butenediol or its polyether of the above formula in amounts of 0.3 to 15 parts by weight, in particular, in amounts of 0.5 to 6 parts by weight, most preferably in amounts of 1 to 5 parts by weight.
The rubbers to be used for the production of the rubber mixtures according to the present invention include natural rubber and synthetic rubbers. Preferred synthetic rubbers are for example described in W. Hofmann, Kautschuktechnologie, Genter Verlag, Stuttgart 1980. These synthetic rubbers include, inter alia
BR—
polybutadiene
ABR—
butadiene/acrylic acid C
1
-C
4
alkyl ester copolymers
CR—
polychloroprene
IR—
polyisoprene
SBR—
stirene/butadiene copolymers with stirene contents in the
range from 1 to 60 wt. %, preferably in the range from 20 to
50 wt. %
IIR—
isobutylene/isoprene copolymers
NBR—
butadiene/acrylonitrile copolymers with acrylonitrile contents
in the range from 5 to 60 wt. %, preferably in the range from
10 to 40 wt. %
HNBR—
partially hydrogenated or completely hydrogenated NBR
rubber
EPDM—
ethylene/propylene/diene copolymers
as well as mixtures of these rubbers.
Mixtures of, in particular, natural rubber, emulsion SBR rubber as well as solution SBR rubber and polybutadiene rubber are of importance in the production of vehicle tires. Of particular interest is the use of solution SBR rubbers with a vinyl content in the range from 20 to 60 wt. % as well as polybutadiene rubbers with a high 1,4-cis content (>90%) that have been produced using catalysts based on nickel, cobalt, titanium and/or neodymium, as well as polybutadiene rubber with a vinyl content of up to 75 wt. % as well as the mixtures of the aforementioned solution SBR and polybutadiene rubbers. Most preferred are corresponding solution SBR and polybutadiene rubbers with an additional content of bound functional groups, in particular hydroxyl and/or carboxyl groups. Preferred contents of hydroxyl and/or carboxyl groups are in the range from 0.05 to 3 wt. % with respect to the rubber. More preferred rubbers according to the present invention are described, for example, in German patent applications DE-A1 19 832 549, DE-A1 19 852 648, DE-A1 19 914 848, DE-A1 19 920 788, DE-A1 19 920 814 as well as DE-A 2 653 144 and EP A1 0 464 478.
Furthermore, the rubber mixtures according to the present invention preferably contain 5 to 300 parts by weight of fillers. Particularly suitable as fillers are oxidic and/or silicate fillers and/or carbon blacks. Oxidic and/or silicate fillers are preferred.
The following suitable oxidic and/or silicate fillers are preferably used:
Highly dispersed silicic acid produced, for example, by precipitating solutions of silicates or by flame hydrolysis of silicates, silicon halides with specific surfaces in the range from 5 to 1000 m
2
/g, preferably in the range from 20 to 400 m
2
/g (BET surface) and with a primary particle size in the range from 10 to 400 nm. The silicic acids 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 aluminum silicate, alkaline earth silicates such as magnesium silicate or calcium silicate with BET surfaces in the range from 20 to 400 m
2
/g and primary particle diameters in the range from 10 to 400 nm.
Natural silicates such as kaolin and other naturally occurring silicic acids.
Glass fibers and glass fiber products (mats, strands) or micro glass spheres.
Metal oxides such as zinc oxide, calcium oxide, magnesium oxide, aluminum oxide.
Metal

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