US 5,852,116 AGranted

Crosslinkable bimodal polyolefin compositions

AssigneeThe Dow Chemical Company

InventorsStephen H. Cree, John Penfold, Line F. Fanichet, Craig A. Wilson

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Abstract

Crosslinkable polyolefin compositions, articles prepared from such compositions, and processes for making such compositions are described that possess both good processability and fast cure rates. The crosslinkable polyolefin compositions are bidisperse blends of ethylene polymers of the same polymer family having differing number average molecular weights as obtained by deconvolution in which M.sub.n1 /M.sub.n2 >7, M.sub.n2 >3000 and 0.7.gtoreq.(A.sub.1 /(A.sub.1 +A.sub.2)).gtoreq.0.15 wherein M.sub.n1 represents the number average molecular weight of the first deconvoluted component, M.sub.n2 represents the number average molecular weight of the second deconvoluted component, and A.sub.1 and A.sub.2 are the relative proportions of the first and second components. These crosslinkable polyolefin compositions are useful for the manufacture of various articles, such as wire and cable coatings, weather-stripping and seals, gaskets, articles made from foamed and/or sponge-like crosslinked polyolefin or either closed or open cell structure and/or combinations thereof, hollow containers, hollow tanks, medical appliances, drapes and coverings, items of health and personal care, fibers, tapes, tubes, pipes and hoses, bellows, boots, gaiters, footwear, etc.

Claims22

Dependent claims

A bimodal polyolefin composition comprising two or more ethylene polymer components and a crosslinking agent, activator, promoter or accelerator, said composition satisfying the following conditions:

M.sub.n1 /M.sub.n2 >7,
M.sub.n2 >3000 and
0.7.gtoreq.(A.sub.1 /(A.sub.1 +A.sub.2)).gtoreq.0.15,
wherein A.sub.1, A.sub.2, M.sub.n1, and M.sub.n2 are derived from the molecular weight distribution of the composition obtained via gel permeation chromatography (GPC) by deconvoluting the relative response (RR) as function of the molecular weight (MW) to fit RR and MW to the following function which is a weighted sum of two log normal distribution functions:
##EQU4## using a nonlinear regression technique to obtain values for A.sub.1, A.sub.2, .mu..sub.1, .mu..sub.2, .sigma..sub.1, and .sigma..sub.2, wherein
MW is the GPC molecular weight value,
RR is the relative response, which for an individual RR/M.sub.w data set is ##EQU5## in which the Normalized Height i! is the GPC output for the corresponding MW i!;
.mu..sub.1 and .sigma..sub.1.sup.2 represent the mean and standard deviation of the first log normal distribution;
.mu..sub.2 and .sigma..sub.2.sup.2 represent the mean and standard deviation of the second log normal distribution;
A.sub.1 +A.sub.2 =1 and 0<A.sub.1 <1;
M.sub.n1 =10.sup..mu.1 exp (-0.5(ln(10).times..sigma..sub.1).sup.2) and
M.sub.n2 =10.sup..mu.2 exp (-0.5(ln(10).times..sigma..sub.2).sup.2),
the composition having an overall density less than 0.907 g/cm.sup.3.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/703,263Filed 26 Aug 1996 · division
Priority: 3 Oct 1995
Granted: 22 Dec 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

C08L 23/04
Not modified by chemical after-treatment: homopolymers or copolymers of ethene
C08L 23/0815
With unsaturated hydrocarbons only containing four or more carbon atoms: with aliphatic 1-olefins containing one carbon-to-carbon double bond
C08L 2205/02
Polymer mixtures characterised by other features: containing two or more polymers of the same C08L -group
C08L
Compositions of macromolecular compounds