Rubber toughened blends

Details Rubber toughened blends Rubber toughened blends

1998-07-17

2001-10-16

Woodward, Ana (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S064000, C525S066000, C525S067000

Reexamination Certificate

active

06303688

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a rubber toughened thermoplastic composition comprising a functionalized ethylene polymer, an elastomer and a thermoplastic polymer.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,346,963 describes substantially linear olefin polymers produced by Dow Chemical Company's “constrained geometry” catalysts grafted with an unsaturated organic compound which exhibit adhesive properties as well as imparting desirable impact properties to various thermoplastic polymer blends. The disclosure does not describe however the combination of a grafted ethylene polymer and an elastomer used to modify a thermoplastic polymer to achieve improved low temperature impact properties.
SUMMARY OF THE INVENTION
This invention relates to a rubber toughened thermoplastic composition comprising an ethylene copolymer grafted with an unsaturated acid or anhydride, an elastomer and a thermoplastic polymer comprising a functional group capable of interacting with the unsaturated acid or anhydride.
DETAILED DESCRIPTION
This invention relates to a rubber toughened thermoplastic composition comprising:
a) 5 to 50 weight % of an ethylene polymer having a Composition Distribution Breadth Index of 50% or more grafted with an unsaturated acid or anhydride and an elastomer; and
b) 95 to 50 weight percent of a thermoplastic polymer comprising a functional group capable of interacting with the unsaturated acid or anhydride.
In a preferred embodiment the ethylene polymer and the elastomer, which together make up component a) above, are present at 5 to 30 weight percent, even more preferably 10 to 25 weight percent and the thermoplastic polymer is present at 95 to 70 weight percent, more preferably 90 to 75 weight percent, based upon the weight of the ethylene polymer, the elastomer and the thermoplastic polymer.
In a preferred embodiment component a) comprises about 10 to about 70 weight % ethylene polymer, more preferably 15 to 50 weight percent ethylene polymer and about 90 to 30 weight percent elastomer, even more preferably 85 to 50 weight percent, based upon the weight of the ethylene polymer and the elastomer.
In a preferred embodiment the ethylene polymer is homopolymer of ethylene or copolymer of ethylene and an &agr;-olefin, preferably a C
3
to C
40
&agr;-olefin, even more preferably a C
3
to C
18
&agr;-olefin, even more preferably a C
3
to a C
12
&agr;-olefin. In a preferred embodiment the ethylene polymer has a molecular weight distribution (Mw/Mn) of 4 or less, preferably 3 or less, even more preferably 2 or less, even more preferably between 2 and 1. In another preferred embodiment the ethylene copolymer has a Composition Distribution Breadth Index (CDBI)of 50% or more, preferably 60% or more, even more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more. CDBI is a measure of the uniformity of comonomer distribution within a given sample and is measured according to the method described in PCT publication WO 93-03093, published Feb. 18, 1993. A homopolymer has a CDBI of 100%. The ethylene polymer may have an Melt Index of 150 g/10 min or less, preferably 20 g/10 min or less, even more preferably 10 g/10 min or less, even more preferably 5g/10 min or less.
The ethylene polymer further comprises an unsaturated acid or anhydride. Preferred unsaturated acid or anhydride include any unsaturated organic compound containing at least one double bond and at least one carbonyl group. Representative acids include carboxylic acids, anhydrides, esters and their salts, both metallic and non-metallic. Preferably the organic compound contains an ethylenic unsaturation conjugated with a carbonyl group (—C═O). Examples include maleic, fumaric, acrylic, methacrylic, itaconic, crotonic, &agr;-methyl crotonic, and cinnamic acids as well as their anhydrides, ester and salt derivatives. Maleic anhydride is particularly preferred. The unsaturated acid or anhydride is preferably present at about 0.1 weight % to about 10 weight %, preferably at about 0.5 weight % to about 5 weight %, even more preferably at about 1 to about 3 weight %, based upon the weight of the ethylene polymer and the unsaturated acid or anhydride.
Ethylene polymers having narrow Mw/Mn and high CDBI's can be produced by the methods described in U.S. Pat. No. 5,055,438; U.S. Pat. No. 5,507,475; U.S. Pat. No. 5,096,867; U.S. Pat. No. 5,264,405; U.S. Pat. No. 5,324,800; U.S. Pat. No. 5,017,714; U.S. Pat. No. 5,240,894; U.S. Pat. No. 5,198,401; U.S. Pat. No. 5,153,157; WO 92 00333; WO 94 03506; EPA 520,732; EPA 129,368; EPA 277,003; EPA 277,004; and CA 1,268,753, which are incorporated by reference herein. Such polymers are available from Exxon Chemical Company in Baytown, Tex. under the Tradenames EXCEED™ and EXACT
. These polymers can be modified to contain the unsaturated acid or anhydride group by methods known in the art, such as U.S. Pat. Nos. 3,326,917, 4,950,541 and 5,194,509, which are incorporated by reference herein.
In a preferred embodiment the elastomer is any elastomer typically known in the art, including but not limited to, ethylene based elastomers, such as styrene-butadiene rubber, ethylene propylene rubber, ethylene propylene diene monomer rubber; styrene based elastomers such as styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers; isobutylene based polymers such as polyisobutylene, isobutylene-isoprene rubber, isosbutylene-para-methylstyrene rubber, natural rubber. Other commercially available rubbers are also acceptable elastomers, such as polychloroprene, nitrile rubber, polybutadiene, polyisoprene, poly(butadiene-co-styrene). For more information on the properties of the various elastomers and their manufacture, see Morton,
Rubber Technology
, Van Nostrand Reinhold, London, England 1987. In another embodiment the elastomer is also functionalized with an unsaturated acid or anhydride group. For example maleated EPDM can be used as the elastomer. Typical molecular weights are greater than 50,000, even more preferably greater than 100,000.
In a particularly preferred embodiment, the elastomer is 30 an ethylene-higher &agr;-olefin, polymer composition comprising:
i) a first polymer fraction having a number average molecular weight of from 10,000 to 500,000, an ethylene content of from 30 to 80 weight %, preferably 40 to 80 weight %, even more preferably 50-70 weight %, and a diene content of from 1 to 12 weight %, preferably 1.5 to 10 weight %, even more preferably 2 to 6 weight %, based upon the weight of the polymer; and
ii) a second polymer fraction having a number average molecular weight of from 100,000 to 10,000,000, preferably 200,000 to 1,000,000, an ethylene content of from 40 to 90 weight %, preferably 40 to 80 weight %, even more preferably 50-70 weight %, and a diene content of from 0 to 12 weight %, preferably 0 to 8 weight %, even more preferably 0 to 6 weight %, based upon the weight of the polymer; provided that:
a) the second fraction has a higher molecular weight than the first fraction,
b) the second fraction has an equal or higher ethylene content than the first fraction,
c) the weight ratio of diene in the first fraction to diene in the second fraction can vary from 0.5 to 1, from 2.0 tol or even more (when the second fraction has no diene the ratio is of course infinity), in preferred embodiments the ratio is at least 0.5 to 1, preferably at least 0.8 to 1,
d) the Mw/Mn of each fraction is independently from 2 to 6.5, preferably 2 to 5, even more preferably 2 to 4 and
e) the first fraction comprises 60 to 95 weight %, preferably 70-95 weight % of the total polymer composition.
In general, however these ethylene-higher &agr;-olefin polymers are copolymers of ethylene and a C
3
to C
8
&agr;-olefin, preferably propylene and an optional diene, preferably a non-conjugated diene. Preferred dienes include straight chain alicyclic dienes (such as 1,4 hexadiene), branched chain dienes, acyclic dienes (such as 5-methyl-1,6-hexadiene), single ring alicyclic dienes (such as 1,4-cyclohexadiene),

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