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US 5,182,333 AGranted
Production of rubbery isoolefin polymers
AssigneeExxon Chemical Patents Inc.
InventorsKenneth W. Powers, Hsien-Chang Wang, Debra C. Handy, James V. Fusco
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AssigneeExxon Chemical Patents Inc.
InventorsKenneth W. Powers, Hsien-Chang Wang, Debra C. Handy, James V. Fusco
Estimating the term…
A substantially gel free C.sub.4 to C.sub.7 isoolefin homopolymer rubber, butyl copolymer rubber, halogenated butyl rubber (e.g., chlorinated or brominated), or mixtures thereof, comprising a molecular weight distribution such that the ratio of the moments of said molecular weight distribution, Mz/Mw, is equal to or exceeds 2.0, and that portion of said molecular weight distribution which is equal to and greater than 4 times the peak molecular weight, Mp, comprises greater than 8 percent of the total polymer species, and Mp is greater than about 250,000 and wherein said polymer species of molecular weight less than Mp are substantially branch free. Various means are disclosed for effecting the molecular weight distribution including blending of homopolymers and/or copolymers of appropriate molecular weight and molecular weight distribution and direct polymerization using a functional reagent to introduce branching. The rubber compositions are particularly useful in applications in which butyl or halogenated butyl rubber is used and where it is desired to obtain high green strength in combination with an increased rate of stress relaxation. Such polymers are particularly well suited for use in tire innerliner compositions.
A process for producing a composition of matter comprising a C.sub.4 to C.sub.7 isoolefin homopolymer rubber, butyl copolymer rubber, or mixtures thereof, wherein the molecular weight distribution of said rubber or said mixture is such that the ratio of the moment of said molecular weight distribution, Mz/Mw, is equal to 2.0 to about 11.0 and that portion of said molecular weight distribution which is equal to or greater than 4 times the peak molecular weight, Mp comprises from about 8 to about 25 weight percent of the total polymer species, Mp is about 250,00 to about 850,000 and wherein said polymer species of molecular weight less than Mp are substantially branch free, said process comprising the step of polymerizing a C.sub.4 to C.sub.7 isoolefin, or a mixture of a C.sub.4 to C.sub.7 isoolefin and a C.sub.4 to C.sub.14 conjugated diene, and incorporating an effective amount of a cationically functional reagent during said polymerizing step, at conditions such that substantially all of said cationically functional reagent is grafted to said polymer.
Dependencies are inferred from the claim text.