Rubber mixes containing polyether/diolefin rubbers and use...

Details Rubber mixes containing polyether/diolefin rubbers and use... Rubber mixes containing polyether/diolefin rubbers and use...

2001-11-14

2003-02-11

Seidleck, James J. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S359200, C525S162000, C525S118000, C525S098000, C525S088000

Reexamination Certificate

active

06518369

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to filled rubber mixes made from special rubbers based on polyethers and diolefins and optionally vinyl aromatics. The rubber mixes according to the present invention are suitable for the production of highly reinforced, abrasion-resistant moldings, in particular, for the production of tires which exhibit low rolling resistance and elevated wet skid resistance.
BACKGROUND OF THE INVENTION
Anionically polymerized solution rubbers containing double bonds, such as solution polybutadiene and solution styrene/butadiene rubbers, have advantages over corresponding emulsion rubbers in the production of tire treads with low rolling resistance. The advantages reside inter alia in the controllability of the vinyl content and thus, of glass transition temperature and molecular branching, which are associated therewith. In practice, this gives rise to particular advantages with regard to the tire's relationship of wet skid resistance to rolling resistance. Accordingly, U.S. Pat. No. 5,227,425 describes the production of tire treads from a solution SBR rubber and silica. In order to achieve a further improvement in properties, numerous methods have been developed for modifying end groups, as described in EP-A 334 042, with dimethylaminopropylacrylamide, or, as described in EP-A 447 066, with silyl ethers. However, due to the elevated molecular weight of the rubbers, the content by weight of the end group is low and is thus, able to have only a slight influence upon the interaction between the filler and the rubber molecule. The object of the present invention was to provide solution rubbers having a higher content by weight of effective polar groups.
U.S. Pat. No. 3,360,571 describes a process for the production of polyether/diolefin block polymers by anionic solution polymerization of a diolefin and further reaction of the living polymer anion with ethylene oxide. The use of ethylene oxide entails elaborate processing technology. The listed polyethylene oxide/diolefin block copolymers moreover have low molecular weights (500 to 50,000) and are primarily intended for coatings.
U.S. Pat. No. 3,419,505 describes a process for the production of ethylene oxide/diolefin copolymers, wherein polymerization is performed in the presence of iron, aluminum and phosphorus catalysts. The process has the disadvantage that large quantities of catalysts containing iron are required, the presence of which is undesirable in the finished rubber, because iron compounds have a negative impact upon ageing characteristics. The cited document makes no reference to the use of the rubbers in low-damping tires.
German patent application no. 100 099 092 describes rubbers with polyether side groups. These rubbers differ with regard to their chemical structure from the rubbers of the present invention. The polyether side groups in the cited application are attached as side groups to the polymer chain via sulfur atoms, whereas in the present invention they act as a binding link in the polymer chain.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide rubber mixes made from special, anionically polymerized polyether/diolefin block polymers together with a simple production process, from which polymers it is possible to produce tires having improved wet skid resistance, lower rolling resistance together with elevated mechanical strength and improved abrasion behavior.
DETAILED DESCRIPTION OF THE INVENTION
Accordingly, the present invention provides rubber mixes made from polyether/diolefin rubbers, which have a content of diolefin incorporated by polymerization of 49.99 to 99.99 wt. %, preferably of 60 to 99.9 wt. %, a content of vinyl aromatic compounds of 0 to 50 wt. %, preferably of 0 to 40 wt. %, and a content of polyether incorporated into the polymer chain of 0.01 to 5 wt. %, preferably of 0.1 to 2 wt. %, wherein the percentages add up to 100 wt. %, and 10 to 500 parts by weight, preferably 20 to 150 parts by weight of filler, relative to 100 parts by weight of rubber.
The rubber mixes according to the present invention may, of course, also contain further rubbers, rubber auxiliaries and vulcanizing agents, which are described below in greater detail.
The polyether/diolefin rubbers used according to the present invention in the rubber mixes are produced by reacting a living polymer anion, which has been obtained by polymerizing at least one diolefin and optionally vinyl aromatic compounds with an anionic initiator, with a reactive polyether of the general formula
in which
A denotes a mono- to tetravalent C
1
-C
24
alkyl residue, a mono- to trivalent C
6
-C
24
aryl residue or a mono- to trivalent C
7
-C
24
alkylaryl residue,
R
1
and R
2
mutually independently mean hydrogen or a methyl, ethyl, propyl or butyl group and
X denotes a halogen atom or a group from the range —O—C
1
-C
24
-alkyl, —O—C
6
-C
24
-aryl or —O—C
7
-C
24
-alkylaryl, providing that at least one residue X denotes a halogen atom,
m denotes an integer from 4 to 30, preferably from 5 to 20, and
q denotes an integer from 1 to 4, preferably from 1 to 3, most preferably 2,
at temperatures in the range from −100 to +150° C.
“A” preferably denotes a methyl, ethyl, propyl, butyl or phenyl group or a difunctional residue from the range —CH
2
CH
2
, —CH
2
CH
2
CH
2
—, —CH
2
C(CH
3
)— or a trifunctional CH
3
CH
2
—C(CH
2
)
3
residue or a tetrafunctional residue C(CH
2
)
4
. More preferred residues A are the methyl residue and the following difunctional groups: —CH
2
CH
2
—, —CH
2
CH
2
CH
2
—, CH
2
C(CH
3
)—, R
1
and R
2
preferably denote H or methyl, more preferably H and X preferably denotes chlorine.
Preferred diolefins for the production of the polyether/diolefin rubbers are 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 1-vinyl-1,3-butadiene and/or 1,3-hexadiene. 1,3-Butadiene and isoprene are more preferably used.
Vinyl aromatic monomers usable for the production of the polyether/diolefin rubbers which may be mentioned by way of example are styrene, o-, m- and p-methylstyrene, p-tert.-butylstyrene, &agr;-methylstyrene, vinyinaphthalene, diphenylethylene, divinylbenzene, trivinylbenzene and/or divinylnaphthalene. Styrene is more preferably used.
Preferred reactive polyethers are chlorine-terminated polyethylene oxides and chlorine-terminated polyethylene oxide/propylene oxide copolyethers having molecular weights in the range from 400 to 2500. Linear, &agr;,&ohgr;-chlorine-terminated polyethylene oxides having (number average) molecular weights of 450 to 1800 are more preferred.
The polyether/diolefin rubbers have average molecular weights (number average) of 100,000 to 2,000,000, preferably of 150,000 to 1,500,000, and glass transition temperatures of −100° to +20° C., preferably of −95° C. to 0° C., and Mooney viscosities ML 1+4 (100° C.) of 10 to 200, preferably of 30 to 150.
Anionic polymerization of the stated starting monomers preferably proceeds by means of an alkali metal-based catalyst, for example n-butyllithium, in an inert hydrocarbon as solvent. Known randomizers and control agents for developing the microstructure of the polymer may additionally be used. Such anionic solution polymerizations are known and are described, for example, in 1. Franta,
Elastomers
&
Rubber Compounding Materials
; Elsevier 1989, pp. 73-74, 92-94 and in Houben-Weyl,
Methoden der Organischen Chemie
, Thieme Verlag, Stuttgart, 1987, volume E20, pp. 114-134.
Examples of suitable alkali metal catalysts are lithium, sodium, potassium, rubidium, caesium metal and the hydrocarbon compounds thereof and complex compounds thereof with polar organic compounds.
Lithium and sodium hydrocarbon compounds having 2 to 20 carbon atoms are particularly preferably used, for example ethyllithium, n-propyllithium, i-propyllithium, n-butyllithium, sec.-butyllithium, tert.-octyllithium, n-decyllithium, phenyllithium, 2-naphthyllithium, 2-butylphenyllithium, cyclohexyllithium, 4-cyclopentyllithium, 1,4-dilithio-2-butene, sodium naphthalene,

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