Rubbers with polyether side groups

Details Rubbers with polyether side groups Rubbers with polyether side groups

2001-02-22

2003-02-18

Cain, Edward J. (Department: 1714)

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

active

06521698

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to rubbers based on diolefins with a particular lateral polyether group content and to the use of said rubbers for the preparation of rubber vulcanizates with improved tear propagation resistance and favorable dynamic damping. Additionally, the rubbers according to the present invention are suitable for the manufacture of highly reinforced rubber molded articles, particularly for tires of vehicles which are used both in road traffic and off-road because, in addition to high wet skid resistance, low rolling resistance, high road abrasion resistance, they have high tear propagation resistance with relatively good ability to withstand high stresses off-road.
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 manufacture of low rolling resistance tire treads. The advantages lie, i.a. in the ability to control the vinyl content and the associated glass transition temperature and molecule branching. This results in particular advantages in practical application in the relationship between the wet skid resistance and rolling resistance of the tire. U.S. Pat. No. 5,227,425 describes the manufacture of tire treads from a solution SBR rubber and silica. A disadvantage of such rubber mixtures is the limited tear propagation resistance. New types of motor vehicles which may be used both in road traffic and off-road (“Multi Utility Vehicles”), in addition to the known requirements in terms of rolling resistance, wet skid resistance and abrasion behavior, impose new demands in terms of high tear propagation resistance for the operation of the vehicle off-road.
Rubber mixtures of solution rubbers based on dienes with lateral functional groups are also described in German patent application no. 198 324 596. The hydroxyl groups described there lead to improvements in road-related properties such as rolling resistance, wet braking stability and abrasion, but for off-road use, further improvements in tear propagation resistance are desirable, especially in the silica-filled rubber mixtures with particularly low rolling resistance.
Rubber mixtures containing polyethers as additives are also described in EP-A 869 145. The polyethers, however, are used as antistatic agents. No details about the tear propagation resistance are given in EP-A 869 145.
SUMMARY OF THE INVENTION
The present invention provides for rubbers of diolefins and optionally other monomers with a relatively high content of effective polyether side groups, from which it is possible to manufacture tires with improved properties for both road and off-road use, more particularly with low rolling resistance, relatively high wet skid resistance, low abrasion and high tear propagation resistance.
Surprisingly, it has now been found that solution rubbers of diolefins with a particular hydroxyl group-free polyether side group content have particularly favorable properties for the manufacture of tires for the multi utility vehicles described.
DETAILED DESCRIPTION OF THE INVENTION
Therefore, the present invention provides rubbers based on diolefins and optionally other monounsaturated monomers containing 10 to 80 wt. %, preferably 20 to 60 wt. % of 1,2-bound diolefins (vinyl content), which are characterized in that they contain 0.01 to 20 wt. %, preferably 0.1 to 15 wt. %, most preferably 0.5 to 10 wt. %, based on the total amount of rubber, of hydroxyl group-free polyether side groups.
The hydroxyl group-free polyether side groups correspond to the formulae (I) or (II)
wherein
R
1
and R
2
independently of one another, is hydrogen or a C
1
to C
6
-alkyl
radical or a —COO—(CHR
3
—CHR
4
—O—)
m
—R
5
radical,
R
3
and R
4
independently of one another and regardless of their meaning
in the other repeat units, stand for hydrogen or a methyl
or ethyl group,
R
5
means a linear, branched or cyclic C
1
to C
24
-alkyl radical,
C
6
to C
18
-aryl or C
7
to C
24
-arylalkyl radical
and
n
stands for an integer from 1 to 6, preferably 1 to 4, and
m
stands for an integer from 1 to 100, preferably 3 to 30
Polyether side groups corresponding to the following formulae are preferred:
Polyethylene oxide polyether —R
5
Molecular weight 132 to about 1500
Polypropylene oxide polyether —R
5
Molecular weight 174 to about 1500
Propylene oxide/ethylene oxide mixed polyether —R
5
Molecular weight 146 to about 1500
Polyethylene oxide polyether —R
5
Molecular weight 132 to about 1500
Polypropylene oxide polyether —R
5
Molecular weight 174 to about 1500
Polypropylene oxide/ethylene oxide mixed polyether —R
5
Molecular weight 146 to about 1500
Polyethylene oxide polyether —R
5
Molecular weight 132 to about 1500
Polyethylene oxide polyether —R
5
Molecular weight 132 to about 1500
Polyethylene oxide polyether —R
5
Molecular weight 174 to about 1500
Polyethylene oxide polyether —R
5
Molecular weight 132 to about 1500
Polypropylene oxide/ethylene oxide mixed polyether —R
5
Molecular weight 146 to about 1500
The R
5
radicals herein stand for C
1
to C
24
-alkyl radicals, preferably C
1
to C
8
-alkyl radicals, C
6
to C
18
-aryl radicals, preferably C
6
to C
10
-aryl radicals, and C
7
to C
24
-arylalkyl radicals, preferably C
7
to C
18
-arylalkyl radicals. More preferred R
5
radicals are methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, octadecyl, phenyl, octyl-phenyl, nonylphenyl and dodecylphenyl groups. The most preferred groups are methyl, ethyl, propyl, butyl, hexyl and octyl groups.
Preferred rubbers according to the present invention are those containing 0.1 to 15 wt. %, based on the total amount of rubber, of polyether side groups corresponding to formula (I).
Preferred rubbers according to the present invention contain, in addition to the diolefins, 0.1 to 50 wt. %, preferably 10 to 40 wt. %, based on the total amount of rubber, of vinylaromatic monomers incorporated by polymerization as further unsaturated monomers.
Moreover, the rubbers according to the present invention may also contain a 1,4-trans proportion of up to 60 wt. %, preferably from 10 to 40 wt. %, based on the total amount of diolefin incorporated by polymerization.
Diolefins used according to the present invention for the preparation of the rubbers include, in particular, 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-diemethylbutadiene, 1-vinyl-1,3-butadiene and/or 1,3-hexadiene. 1,3-Butadiene and/or isoprene are preferred.
Examples of vinylaromatic monomers which may be used for polymerization include styrene, o-, m- and p-methylstyrene, p-tert.-butylstyrene, &agr;-methylstyrene, vinyl naphthalene, divinylbenzene, trivinylbenzene and/or divinylnaphthalene. Styrene is particularly preferred.
The rubbers according to the present invention have molecular weights (number-average) from about 50,000 to 2,000,000, preferably 100,000 to 1,000,000, glass transition temperatures from −120° C. to +20° C., preferably −60° C. to 0° C., and Mooney viscosities ML 1+4 (100° C.) from 10 to 200, preferably from 30 to 150.
The rubbers according to the present invention are prepared preferably by polymerization in solution in an inert organic solvent suitable for the purpose, using a suitable catalyst, preferably an anionic catalyst, for example, based on an alkali metal such as n-butyllithium. In addition, the well-known randomizers and control agents may be used in this polymerization to control the microstructure of the rubber. Anionic solution polymerization reactions of this kind are well known and described, e.g., in I. Franta Elastomers and Rubber Compounding Materials; Elsevier 1989, page 73-74, 92-94 and in Houben-Weyl, Methoden der Organischen Chemie, Thieme Verlag, Stuttgart, 1987, Vol. E 20, page 114-134.
The introduction of the polyether side groups into the rubber takes place preferably after polymerization of the monomers used has taken place in solution by reacting the polymers obtained, preferably in the presence of well known rad

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