Articles having improved clarity, prepared from propylene-ethylene copolymers

Abstract

Molded articles are prepared from propylene-ethylene copolymers and exhibiting improved clarity and strength properties. Articles prepared include bottles and other thin-walled articles. The articles are prepared using an isotactic propylene-ethylene random copolymer resin having an ethylene content of from about 0.5 to about 3 percent by total weight of copolymer, with a xylene solubles content of less than about 1.5 percent. The injection molded article may exhibit less than about 20 percent haze, as determined by ASTM D1003, at a thickness of about 0.08 inch (2.03 mm). Articles may also be prepared from similar copolymers having an ethylene content greater than about 3 percent by total weight of copolymer, with a xylene solubles content of less than about 4 percent by total weight of copolymer. These articles may exhibit less than about 13 percent haze, as determined by ASTM D1003, at a thickness of about 0.08 inch (2.03 mm).

1 . A molded article comprising an isotactic propylene-ethylene random copolymer resin having an ethylene content of from about 0.5 to about 3 percent by total weight of copolymer, with a xylene solubles content of less than about 1.5 percent by total weight of copolymer, suitable to form an injection molded article exhibiting less than about 20 percent haze, as determined by ASTM D1003, at a thickness of about 0.08 inch (2.03 mm).  
   
   
       2 . The article of  claim 1 , wherein the resin has a melt flow rate of less than about 20 g/10 min, as determined by ASTM D-1238, Procedure B, and the injection molded article exhibits less than 13 percent haze, as determined by ASTM D1003, at a thickness of about 0.08 inch (2.03 mm).  
   
   
       3 . The article of  claim 2 , wherein the resin has a melt flow rate of from about 7 g/10 min to about 15 g/10 min.  
   
   
       4 . The article of  claim 1 , wherein the resin has a melt flow rate of greater than about 20 g/10 min, as determined by ASTM D-1238, Procedure B.  
   
   
       5 . The article of  claim 4 , wherein the resin is suitable to form an injection molded article exhibiting a flexural modulus of less than about 2.25×10 5  psi (1551 mPa), as determined by ASTM D790-97.  
   
   
       6 . The article of  claim 1- , wherein the resin comprises a clarity-enhancing agent in an amount of from about 0.01 to about 0.5 percent by total weight of resin.  
   
   
       7 . The article of  claim 6 , wherein the clarity-enhancing agent is selected from the group consisting of acetals of sorbitols, acetals of xylitols, phosphate ester salts, minerals, aromatic carboxylic salts, dicarboxylic acid salts, and combinations thereof.  
   
   
       8 . The article of  claim 1 , wherein the resin has an ethylene content of from about 0.5 to about 2 percent by total weight of copolymer.  
   
   
       9 . The article of  claim 1 , wherein the article is prepared by injection molding or blow-molding the resin.  
   
   
       10 . The article of  claim 1 , wherein the article is selected from a group consisting of housewares, food storage containers, cooking utensils, plates, cups, drinking cups, measuring cups, strainers, turkey basters, non-food storage containers, filing cabinets, cabinet drawers, general storage devices, organizers, totes, sweater boxes, rigid packaging, deli containers, deli container lids, dairy containers, dairy container lids, personal care products, bottles and jars, furniture, furniture components, building materials and building container components, films, coatings, fibers, bags, adhesives, yarn and fabric.  
   
   
       11 . A molded article comprising an isotactic propylene-ethylene random copolymer resin having an ethylene content of greater than about 3 percent by total weight of copolymer, with a xylene solubles content of less than about 4 percent by total weight of copolymer, suitable to form an injection molded article exhibiting less than about 13 percent haze, as determined by ASTM D1003, at a thickness of about 0.08 inch (2.03 mm).  
   
   
       12 . The article of  claim 11 , wherein the resin has a melt flow rate of less than about 20 g/10 min, as determined by ASTM D-1238, Procedure B, and the injection molded article exhibits less than 10 percent haze, as determined by ASTM D1003, at a thickness of about 0.08 inch (2.03 mm).  
   
   
       13 . The article of  claim 11 , wherein the resin has a melt flow rate of from about 7 g/10 min to about 15 g/10 min.  
   
   
       14 . The article of  claim 11 , wherein the resin has a melt flow rate of greater than about 20 g/10 min, as determined by ASTM D-1238, Procedure B.  
   
   
       15 . The article of  claim 11 , wherein the resin is suitable to form an injection molded article exhibiting a flexural modulus of less than 1.5×10 5  psi (1034 mPa), as determined by ASTM D790-97.  
   
   
       16 . The article of  claim 11 , wherein the resin contains a clarity-enhancing agent in an amount of from about 0.01 to about 0.75 percent by total weight of resin.  
   
   
       17 . The article of  claim 16 , wherein the clarity-enhancing agent is selected from the group consisting of acetals of sorbitols, acetals of xylitols, phosphate ester salts, minerals, aromatic carboxylic salts, dicarboxylic acid salts, and combinations thereof.  
   
   
       18 . The article of  claim 11 , wherein the resin has an ethylene content of from about 3 to about 5 percent by total weight of copolymer.  
   
   
       19 . The article of  claim 11 , wherein the article is prepared by injection molding or blow-molding the resin.  
   
   
       20 . The article of  claim 11 , wherein the article is selected from the group consisting of housewares, food storage containers, cooking utensils, plates, cups, drinking cups, measuring cups, strainers, turkey basters, non-food storage containers, filing cabinets, cabinet drawers, general storage devices, organizers, totes, sweater boxes, rigid packaging, deli containers, deli container lids, dairy containers, dairy container lids, personal care products, bottles, jars, furniture, furniture components, building materials and building container components, films, coatings, fibers, bags, adhesives, yarn and fabric.