Polymer composition having elastomeric features
Polymer compositions having elastomeric features, such as an extended elastic domain, are provided. The polymer compositions of the invention, which are useful in packaging materials, for example pallet stretch hoods, comprise a polyolefin; an ethylene vinyl acetate copolymer, an ethylene methyl acrylate copolymer, or a combination of ethylene vinyl acetate copolymer and a ethylene methyl acrylate copolymer; a metallocene catalyzed polyethylene; and, optionally, an ethylene acid copolymer.
1 . A polymer composition comprising
a polyolefin;
an ethylene vinyl acetate copolymer, an ethylene methyl acrylate copolymer, or a combination of an ethylene vinyl acetate copolymer and an ethylene methyl acrylate copolymer; and
a metallocene catalyzed polyethylene; and, optionally, an acid copolymer, provided that the acid copolymer is present in a finite amount when the amount of ethylene methyl acrylate copolymer is zero;
said polymer composition having at least one elastomeric feature.
2 . The polymer composition of claim 1 , comprising
a finite amount of the polyolefin up to about 80 wt % based on the total weight of the polymer composition;
a finite amount of the ethylene vinyl acetate copolymer, the ethylene methyl acrylate copolymer, or the combination of ethylene vinyl acetate copolymer and ethylene methyl acrylate copolymer up to about 80 wt % based on the total weight of the polymer composition;
a finite amount of metallocene catalyzed polyethylene up to about 30 wt % based on the total weight of the polymer composition; and,
when the amount of ethylene methyl acrylate copolymer is zero, a finite amount of the acid copolymer up to about 30 wt % based on the total weight of the polymer composition.
3 . The polymer composition of claim 1 , comprising
about 20 to about 70 wt % of the polyolefin, based on the total weight of the polymer composition;
about 20 to about 70 wt % of the ethylene vinyl acetate copolymer, the ethylene methyl acrylate copolymer, or the combination of ethylene vinyl acetate copolymer and ethylene methyl acrylate copolymer, based on the total weight of the polymer composition;
about 20 to about 70 wt % of the metallocene catalyzed polyethylene, based on the total weight of the polymer composition; and
when the amount of ethylene methyl acrylate copolymer is zero, about 5 to about 20 wt % of the acid copolymer based on the total weight of the polymer composition.
4 . The polymer composition of claim 1 , comprising
about 5 to about 15 wt % of the polyolefin based on the total weight of the polymer composition;
about 40 to about 60 wt % of the ethylene vinyl acetate copolymer, the ethylene methyl acrylate copolymer, or the combination of ethylene vinyl acetate copolymer and ethylene methyl acrylate copolymer, based on the total weight of the polymer composition;
about 40 to about 60 wt % of the metallocene catalyzed polyethylene, based on the total weight of the polymer composition; and,
when the amount of ethylene methyl acrylate copolymer is zero, about 5 to about 15 wt % of acid copolymer based on the total weight of the polymer composition.
5 . The polymer composition of claim 1 , wherein the polyolefin is an ethylene polymer.
6 . The polymer composition of claim 5 , wherein the polyolefin is an ethylene homopolymer or an ethylene interpolymer selected from the group consisting of low density polyethylene, heterogeneously branched ethylene/α-olefin interpolymer, ultra low density polyethylene, substantially linear ethylene polymers, and homogeneously branched ethylene polymers.
7 . The polymer composition of claim 1 , wherein the ethylene vinyl acetate copolymer comprises 10 wt % to 25 wt % of vinyl acetate comonomer residues.
8 . The polymer composition of claim 7 , wherein the ethylene vinyl acetate copolymer comprises 12 wt % to 18 wt % of vinyl acetate comonomer residues.
9 . The polymer composition of claim 1 , wherein the ethylene vinyl acetate copolymer has a melting point greater than about 80° C.
10 . The polymer composition of claim 1 , wherein the ethylene vinyl acetate copolymer has a melt flow index between 0.1 g/10 min and 10 g/10 min when measured according to ASTM D1238.
11 . The polymer composition of claim 10 , wherein the ethylene vinyl acetate copolymer has a melt flow index between 0.3 g/10 min and 1 g/10 min when measured according to ASTM D1238.
12 . The polymer composition of claim 1 , wherein the ethylene methyl acrylate copolymer is prepared in a tubular reactor.
13 . The polymer composition of claim 1 , wherein the ethylene methyl acrylate copolymer comprises more than 10 wt % of methyl acrylate comonomer, based on the weight of the ethylene methyl acrylate copolymer.
14 . The polymer composition of claim 13 , wherein the ethylene methyl acrylate copolymer comprises more than 25 wt % of methyl acrylate comonomer, based on the weight of the ethylene methyl acrylate copolymer.
15 . The polymer composition of claim 1 , wherein the ethylene methyl acrylate copolymer has a melt flow index less than 5 g/10 min when measured according to ASTM D1238.
16 . The polymer composition of claim 15 , wherein the ethylene methyl acrylate copolymer has a melt flow index less than 1 g/10 min when measured according to ASTM D1238.
17 . The polymer composition of claim 1 , wherein the metallocene catalyzed polyethylene has a melt flow index less than 2.5 g/10 min when measured according to ASTM D1238.
18 . The polymer composition of claim 17 , wherein the metallocene catalyzed polyethylene has a melt flow index less than 1.0 g/10 min when measured according to ASTM D1238.
19 . The polymer composition of claim 18 , wherein the metallocene catalyzed polyethylene has a melt flow index less than 0.5 g/10 min when measured according to ASTM D1238.
20 . The polymer composition of claim 19 , wherein the metallocene catalyzed polyethylene has a melt flow index less than 0.3 g/10 min when measured according to ASTM D1238.
21 . The polymer composition of claim 1 , wherein the acid copolymer is selected from the group consisting of ethylene/(meth)acrylic acid, ethylene/(meth)acrylic acid/n-butyl(meth)acrylate, ethylene/(meth)acrylic acid/iso-butyl(meth)acrylate, ethylene/(meth)acrylic acid/methyl(meth)acrylate, and ethylene/(meth)acrylic acid/ethyl(meth)acrylate.
22 . An object comprising the polymer composition of claim 1 .
23 . A pallet stretch hood comprising the polymer composition of claim 1 .
24 . A method of increasing the elastic domain of a polymer blend, comprising the steps of:
providing a polyolefin and an ethylene vinyl acetate copolymer, an ethylene methyl acrylate copolymer, or a combination of an ethylene vinyl acetate copolymer and an ethylene methyl acrylate copolymer; and
blending the polyolefin and the ethylene vinyl acetate copolymer, the ethylene methyl acrylate copolymer, or the combination of ethylene vinyl acetate copolymer and ethylene methyl acrylate copolymer with a metallocene catalyzed polyethylene, and, optionally, an acid copolymer.