Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
2000-06-27
2002-02-26
Moore, Margaret G. (Department: 1712)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S151000, C525S279000, C525S332900, C525S333200, C528S423000, C526S108000, C502S157000, C502S167000
Reexamination Certificate
active
06349753
ABSTRACT:
TECHNICAL FIELD
The subject invention relates to polymers made by anionic initiation with alkyllithium compounds containing cyclic amines, such as polymerizations of dienes and diene/comonomer mixtures resulting in diene polymer and copolymer elastomers. Polymers prepared with the compounds of the present invention exhibit improved characteristics such as for example, improved hysteresis loss characteristics, and reproducible, relatively narrow range molecular weight distributions.
BACKGROUND ART
When conducting polymerizations on a commercial basis, it is important to utilize process conditions and components which will allow the molecular weight of the end products to be narrowly and reproducibly defined. The characteristics of a given polymer and its usefulness, are dependent, among other things, upon its molecular weight. Hence, it is desirable to be able to predict with some certainty the molecular weight of the end product of the polymerization. When the molecular weight is not narrowly definable, or is not reproducible on a systematic basis, the process is at a commercial disadvantage.
Further, it is desirable to produce elastomeric compounds exhibiting improved characteristics such as reduced hysteresis loss characteristics. Such elastomers, when compounded to form articles such as tires, power belts and the like, will show an increase in rebound, a decrease in rolling resistance and less heat build-up when mechanical stresses are applied.
A major source of hysteretic power loss has been established to be due to the section of the polymer chain from the last cross link of the vulcanizate to the end of the polymer chain. This free end cannot be involved in an efficient elastic recovery process, and as a result, any energy transmitted to this section of the cured sample is lost as heat. It is known in the art that this type of mechanism can be reduced by preparing higher molecular weight polymers which will have fewer end groups. However, this procedure is not useful because processability of the rubber with compounding ingredients and during shaping operations decreases rapidly with increasing molecular weight of the rubber.
The present invention provides polymers made by anionic initiation with novel alkyl lithium compounds containing cyclic amines. Use of the compounds of the present invention allows the incorporation of a functionality from the initiator to be incorporated at least at the head of the polymer chain. The initiators used in the invention not only provide for improved polymerizations, but also result in polymers having a relatively predictable, controllable and reproducible molecular weight range distribution. Because of the incorporated functionality, the polymers and products of the invention exhibit improved (that is, reduced) hysteresis loss characteristics.
Certain aminoalkyllithium compounds are known in the art. For example, U.S. Pat. No. 4,935,471 discloses dialkylamino oligoalkenyl lithiums including piperidinyl and pyrrolidinyl oligoalkenyl lithiums. It has been found that when compounded with conventional vulcanizable rubber components, some of these materials do not interact effectively with carbon black. Others possess an odor which makes their commercial use undesirable. The present invention provides polymers derived from aminoalkyllithium compounds with improved interaction with carbon black and which do not have the objectionable odor associated with the piperidinyl and pyrrolidinyl compounds.
DISCLOSURE OF THE INVENTION
It is therefore, an object of the present invention to provide polymers formed by anionic polymerization initiators.
It is a further object of the invention to provide a polymerization initiator which using such to initiate a polymerization will reproducibly result in a polymer within a narrow, predictable molecular weight range.
It is an additional object of the invention to provide a polymerization initiator which using such to initiate a polymerization will allow for the incorporation of a functional group at both the head and tail of the resulting polymer.
It is another object of the present invention to provide elastomers formed with such a polymerization initiator.
It is yet another object of the present invention to provide elastomers having a plurality of polymer molecules wherein substantially each molecule has a functional group from the initiator.
It is also an object of certain embodiments of the present invention to provide diene polymers and copolymers having reduced hysteresis characteristics.
It is a further object of the present invention to provide vulcanizable elastomeric compounds.
Still another object of the present invention is to provide an improved tire formed from an elastomer as described hereinabove.
At least one or more of these objects together with the advantages thereof over the existing art, which shall become apparent from the specification which follows, are accomplished by the invention as hereinafter described and claimed.
In general, according to the invention, a functionalized polymer comprises a polymer molecule having the general formula AYLi where A is a cyclic amine-containing radical having the general formula (I)
wherein R
1
and R2 are as discussed hereinabove; and Y is a divalent polymer radical.
A functionalized polymer according to the present invention also comprises a polymer molecule having the general formula AYLi where A is a cyclic amine-containing radical having the general formula
wherein A, R
2
, R
5
and Y are as discussed hereinabove.
There is also provided according to the invention a method of preparing a polymer which comprises preparing a solution of 1 or more anionically polymerizable monomers in a solvent; and, polymerizing under effective conditions, the monomers in the presence of a polymerization initiator having the general formula
wherein R
1
and R
2
are as discussed hereinabove.
A method for preparing a polymer according to the present invention comprises preparing a solution of 1 or more anionically polymerizable monomers in a solvent; and polymerizing under affective conditions, the monomers in the presence of a polymerization initiator having the general formula
wherein R2 and R
5
are as discussed hereinabove.
PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION
As will become apparent from the description which follows, the present invention employs novel aminoalkyllithium compounds useful for example, as anionic polymerization initiators for the preparation of diene polymer and copolymer elastomers. It has been discovered herein that certain vulcanizable elastomeric compounds and articles thereof based upon such polymers formed using such initiators, exhibit useful properties, such as for example, reproducible relatively narrow molecular weight ranges. Furthermore, such polymers also contain a functionality from the initiator, which functionality is useful for example, in reducing hysteresis loss characteristics in the resulting polymers.
The preferred aminoalkyllithium compound used as anionic initiators in the invention contains a cyclic amine. The preferred initiator is therefore, an amine having the general formula ALi, wherein the component “A” represents the cyclic amine functionality to be incorporated at the initiation site or the head of the resulting polymer when the inventive amine compound is employed as an initiator. “A” is preferably a cyclic amine radical having the general formula (I)
wherein R
1
is a divalent alkylene, oxy- or amino-alkylene, or substituted alkylene moiety having from 6 to about 20 carbon atoms, more preferably from 6 to 12 carbon atoms; and, R
2
is a linear-, branched-, or cyclo-alkylene moiety having from about 2 to about 20 carbon atoms, and more preferably, from 3 to 12 carbon atoms. The lithium atom, Li, is bonded directly to a carbon atom of A.
Examples of R
1
include hexamethylene, heptamethylene, dodecamethylene and hexadecamethylene moieties and the like. Examples of preferred R
2
groups have from about 3 to about 6 carbon atoms and include propyl and hexyl moieties and the like. Hence, examp
Antkowiak Thomas A.
Hall James E.
Lawson David F.
Schreffler John R.
Stayer, Jr. Mark L.
Aylward D.
Bridgestone Corporation
Moore Margaret G.
Palmer Meredith E.
Reginelli Arthur M.
LandOfFree
Aminoalkyllithium compounds containing cyclic amines and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aminoalkyllithium compounds containing cyclic amines and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aminoalkyllithium compounds containing cyclic amines and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2973435