Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
2001-08-14
2002-06-11
Woodward, Ana (Department: 1711)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C525S192000, C525S194000, C525S197000, C525S205000, C152S510000, C152S548000
Reexamination Certificate
active
06401776
ABSTRACT:
BACKGROUND OF THE INVENTION
Thermoplastic elastomers (TPEs) are well known. These materials combine the processing characteristics of thermoplastics with the physical properties of vulcanized rubbers, and they are therefore useful in many applications. TPEs are typically two-phase systems that include a hard thermoplastic phase that is coupled to a soft elastomeric phase, thus resulting in a material that exhibits the combined properties of the two phases.
Well known TPEs include styrene-butadiene-styrene and styrene-ethylene/butylene-styrene copolymers. In these polymers, the hard polystyrene domains are coupled to the soft, elastomeric butadiene or ethylene/butadiene domains. When subject to processing temperatures of roughly 102° C. and above, the polystyrene domains melt and the polymers are readily processable. Below the processing temperature, the polystyrene domains harden and the network is formed. These polymers are useful in coatings, membranes, extruded parts, and many other applications.
Notably, polystyrene domains typically have glass transition temperatures of about 100° C., and therefore TPEs made therewith are stable below this temperature. Above this temperature, however, the advantageous properties attributable to the polystyrene are diminished. Therefore, a need exists for TPEs having thermoplastic domains with higher glass transition temperatures.
SUMMARY OF THE INVENTION
In general the present invention provides a thermoplastic elastomer prepared by a process comprising reacting an elastomer containing at least one reactive halogen atom with a poly(R
1
(R
2
)ethylene-co-maleimide) in the presence of a compatibilizer that reduces surface tension between the elastomer and the poly(R
1
(R
2
)ethylene-co-maleimide) and in the presence of a Lewis base catalyst, where R
1
is a monovalent organic group and R
2
is hydrogen or a monovalent organic group.
The present invention also includes a thermoplastic elastomer produced by a process comprising the steps of in an internal mixer, mixing a poly(R
1
(R
2
) ethylene-co-maleimide) and a compatibilizer, where R
1
is a monovalent organic group and R
2
is a hydrogen or a monovalent organic group, charging to the mixer an elastomer having at least one reactive halogen atom, charging a catalyst to the mixer, and allowing the poly(R
1
(R
2
)ethylene-co-maleimide) and elastomer to react in the presence of the catalyst.
As end products, the method herein provides thermoplastic elastomer comprising a copolymer having at least one of each of the following [I], [II], and [III] units arranged in a block, statistical, or random configuration:
where R
1
is a monovalent organic group, R
2
is hydrogen or a monovalent organic group, and E is an elastomer.
The shortcomings of the prior art have advantageously been overcome by providing a TPE with thermoplastic domains that include maleimide units. As a result, these TPEs are stable at temperatures exceeding 160° C. Further, the synthesis of these TPEs has been facilitated by the discovery that a certain group of extenders, including propylene carbonate, allow soft, elastomeric polymers to be grafted to (co)polymers containing the maleimide units.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
TPEs of this invention include soft domains that derive from an elastomeric polymer and hard domains that derive from copolymers containing maleimide units. The hard and soft domains are chemically bonded to one another.
The TPEs are prepared by reacting a copolymer containing maleimide units with an elastomeric polymer containing at least one reactive halogen. This reaction preferably takes place in the presence of a compatibilizer and a catalyst. In one embodiment, the compatibilizer is propylene carbonate and the reaction is catalyzed by an organic base.
The copolymer containing maleimide units is preferably a poly(R
1
(R
2
)ethylene-co-maleimide) which, includes random and stereo-specific copolymers, including copolymers having alternating R
1
(R
2
)ethylene and maleimide monomer units along the polymer backbone. These molecules may be defined as poly(R
1
(R
2
)ethylene-alt-maleimide) or poly(R
1
(R
2
)ethylene-co-maleimide).
R
1
is a monovalent organic group, and R
2
may be either a hydrogen atom (H) or a monovalent organic group. Preferably, R
1
is selected from hydrocarbyl groups such as alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, cycloalkenyl, substituted cycloalkenyl, aryl, substituted aryl, aralkyl, alkaryl, allyl, and alkynyl groups, with each group preferably containing from 1 carbon atom, or the appropriate minimum number of carbon atoms to form these groups, up to about 20 carbon atoms. These hydrocarbyl groups may contain heteroatoms, such as, but not limited to, N, O, Si, S, and P.
Examples of unsubstituted and substituted alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, cyclopropyl, 2,2-dimethylcyclopropyl, cyclopentyl, cyclohexyl, methoxymethyl, methoxyethyl, methoxypropyl, methoxybutyl, methoxypentyl, methoxyhexyl, methoxyheptyl, methoxyoctyl, methoxynonyl, methoxydecyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, ethoxybutyl, ethoxypentyl, ethoxyhexyl, ethoxyheptyl, ethoxyoctyl, ethoxynonyl, ethoxydecyl, propoxymethyl, propoxyethyl, propoxypropyl, propoxybutyl, propoxypentyl, propoxyhexyl, propoxyheptyl, propoxyoctyl, propoxynonyl, propoxydecyl, butoxybutoxymethyl, butoxyethyl, butoxypropyl, butoxybutyl, butoxypentyl, butoxyhexyl, butoxyheptyl, butoxyoctyl, butoxynonyl, butoxydecyl, pentyloxymethyl, pentyloxyethyl, pentyloxypropyl, pentyloxybutyl, pentyloxypentyl, pentyloxyhexyl, pentyloxyoctyl, pentyloxynonyl, pentyloxydecyl, hexyloxymethyl, hexyloxyethyl, hexyloxypropyl, hexyloxybutyl, hexyloxypentyl, hexyloxyhexyl, hexyloxyheptyl, hexyloxyoctyl, hexyloxynonyl, hexyloxydecyl, heptyloxymethyl, heptyloxyethyl, heptyloxypropyl, heptyloxybutyl, hexyloxypentyl, heptyloxyhexyl, heptyloxyheptyl, heptyloxyoctyl, heptyloxynonyl, heptyloxydecyl, octyloxymethyl, octyloxyethyl, octyloxypropyl, octyloxybutyl, octyloxypentyl, octyloxyhexyl, octyloxyheptyl, octyloxynonyl, octyloxyoctyl, decyloxymethyl, decyloxyethyl, decyloxypropyl, decyloxybutyl, decyloxypentyl, decyloxyhexyl, decyloxyheptyl, 1-methylethyl, 1-methylpropyl, 1-methylbutyl, 1-methylpentyl, 1-methylhexyl, 1-methylheptyl, 1-methyloctyl, 1-methylnonyl, 1-methyldecyl, 2-methylpropyl, 2-methylbutyl, 2-methylpentyl, 2-methylhexyl, 2-methylheptyl, 2-methyloctyl, 2,3-dimethylbutyl, 2,3,3-trimethylbutyl, 3-methylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 2,3,3,4-tetramethylpentyl, 3-methylhexyl, 2,5-dimethylhexyl and similar groups.
Specific examples of poly(R
1
(R
2
)ethylene-co-maleimide) copolymers include poly(isobutylene-co-maleimide), poly(styrene-co-maleimide), poly(&agr;-methylstyrene-co-maleimide), poly(octadecylene-co-maleimide), or mixtures thereof.
Poly(R
1
(R
2
)ethylene-co-maleimide) is preferably formed by imidizing a poly(R
1
(R
2
)ethylene-co-maleic anhydride)with an amine, where R
1
and R
2
are as defined above.
(R
1
(R
2
)ethylene-co-maleic anhydride) polymers are prepared by reacting R
1
(R
2
)ethylene with maleic anhydride. Processes for forming (R
1
(R
2
)ethylene-co-maleic anhydride) are known. For example, preparing these copolymers from electron donor monomers, such as disubstituted ethylene, and electron acceptor monomers, such as maleic anhydride, by complexing the electron acceptor monomers may be carried out in the absence or presence of an organic free radical initiator in bulk, or in an inert hydrocarbon or halogenated hydrocarbon solvents such as benzene, toluene, hexane, carbon tetrachloride, chloroform, as disclosed in Gaylord et al., J. POLY. Sci., Part B, 7, 145 (1969) and M
ACROMOLECULES
, 2, 442 (1969); and Takahashi et al., J M
ACROMOL. SCI
. (Chemistry), A4, 127 (1970).
Copolymers of poly(R
1
(R
2
)ethylene-co-maleic anhydride) are commerci
Foltz Victor J.
Hall James E.
Wang Xiaorong
Bridgestone Corporation
Burleson David G.
Reginelli Arthur M.
Woodward Ana
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