Polyethylene useful for producing film and molded articles in a process which uses solid state stretching

Abstract

Applicants have discovered that certain polyethylene (PE) homopolymers or copolymers of ethylene and C 3 to C 10 alpha-olefin monomers are more suitable for oriented processes than other polyethylene resins In an aspect, the PE has a MFI of 0.3 g/10 min. to 5.0 g/10 min., a melting point of from 110° C. to 140° C., a density of from 0.912 g/cm 3 to 0.965 g/cm 3 (%), a haze of 10% or less, a clarity of at least 90, and a gloss of at least 60. The polyethylene is heated and formed into an article, cooled, and then the article is stretch oriented. In an embodiment, the film, tape, the melt extruded, injection blow molded, injection stretch blow molded, cast, and thermoformed articles that can be produced with this polyethylene has a thickness of 0.1 mil to 100 mils. The polyethylene exhibits excellent elasticity, toughness, stretch and optical properties for such applications.

1 . An article comprised of:
 polyethylene having a melt flow index of from 0.3 g/10 min to 5.0 g/10 min, a density of from 0.912 g/cm 3  to 0.965 g/cm 3 , and a melting point of from 110° C. to 140° C., wherein said polyethylene is formed into an article by melt extrusion, injection molding, blow molding, or casting;   wherein said formed article is cooled and then oriented uniaxially or biaxially into an oriented article; and   wherein the oriented article has a thickness of 0.1 mil to 100 mils, a haze of 10% or less, a clarity of at least 90, and a gloss of at least 60%.   
     
     
         2 . The article of  claim 1 , wherein the polyethylene is further comprised of a copolymer. 
     
     
         3 . The article of  claim 1  wherein the polyethylene is produced using a single site catalyst, such as a metallocene catalyst. 
     
     
         4 . The article of  claim 1 , wherein the article is cast. 
     
     
         5 . The article of  claim 1 , wherein the article is extruded blown film. 
     
     
         6 . The article of  claim 1 , wherein the article is in a form of a seamless tube. 
     
     
         7 . The article of  claim 1 , wherein the article is a bag. 
     
     
         8 . The article of  claim 1 , wherein the article is a packaging or a container. 
     
     
         9 . The article of  claim 1 , wherein the article is injection blow molded. 
     
     
         10 . The article of  claim 1 , wherein the article is injection stretch blow molded. 
     
     
         11 . The article of  claim 1 , wherein the article is thermoformed. 
     
     
         12 . A method of making an article, comprising the steps of:
 providing an extrusion grade polyethylene homopolymer or copolymer having a melt flow index of from 0.3 g/10 min to 5.0 g/10 min, a density of from 0.912 g/cm 3  to 0.965 g/cm 3 , and a melting point of from 110° C. to 140° C.;   heating said polyethylene and forming an extruded, molded, or cast article;   allowing the formed article to cool to a solid state;   reheating the formed article; and   orienting the article uniaxially or biaxially, thereby forming an oriented article.   
     
     
         13 . The method of  claim 12 , wherein the article is uniaxially oriented by stretching said article in a machine direction. 
     
     
         14 . The method of  claim 12 , wherein the article is biaxially oriented by stretching said article in a machine direction and then separately stretching said article in a transverse direction to produce a biaxially-oriented article. 
     
     
         15 . The method of  claim 12 , wherein the article is biaxially oriented by simultaneously stretching said article in a machine direction and stretching said article in a transverse direction to produce a biaxially-oriented article. 
     
     
         16 . The method of  claim 12 , wherein the article is a seamless tube. 
     
     
         17 . The method of  claim 12 , wherein the article is a bag. 
     
     
         18 . The method of  claim 12 , wherein the article is packaging or a container. 
     
     
         19 . The method of  claim 12 , wherein the article is tape. 
     
     
         20 . The method of  claim 12 , wherein the article is a fiber or a monofilament.