Cross-linked polymers and their use in packaging films and injection molded articles

Abstract

Provided are novel cross-linked polymers and their use in various materials, including packaging films and injection molded articles. These polymers, which comprise certain hydroxyl-containing crosslinking compounds, as well as optionally adjuvants, show improved creep resistance when compared to conventional ethylene acrylic or methacrylic acid copolymers and their ionomers.

1 . A polymer composition comprising an ethylene copolymer, said ethylene copolymer comprising copolymerized units of ethylene, about 5 to about 90 wt % of copolymerized units of a first α,β-unsaturated carboxylic acid having 3 to 10 carbon atoms; and optionally about 2 to about 40 wt % of copolymerized units of a derivative of a second α,β-unsaturated carboxylic acid having 3 to 10 carbon atoms; wherein the weight percentages of the copolymerized units are based on the total weight of the ethylene copolymer and the sum of the weight percentages of the copolymerized units is 100 wt %; and wherein optionally at least a portion of the carboxylic acid groups of the copolymerized units of the α,β-unsaturated carboxylic acid units are neutralized to form carboxylate salts;
 a hydroxyl-containing crosslinking agent; and a silane adjuvant. 
 
     
     
         2 . A product of cross-linking the polymer composition of  claim 1 , wherein at least a portion of the carboxylic acid groups or carboxylate groups of two or more ethylene copolymers are reacted with at least two of the hydroxyl groups of the hydroxyl-containing crosslinking agent, so that the hydroxyl-containing crosslinking agent forms a cross-link between two or more ethylene copolymer molecules. 
     
     
         3 . The polymer composition of  claim 1 , wherein about 5% to about 90% of the total content of the carboxylic acid groups present in the ethylene copolymer have been neutralized to form carboxylate groups having counterions. 
     
     
         4 . The polymer composition of  claim 1 , wherein the ethylene copolymer comprises about 10 wt % to about 30 wt % of copolymerized units of the α,β-ethylenically unsaturated carboxylic acid. 
     
     
         5 . The polymer composition of  claim 4 , wherein the α,β-ethylenically unsaturated carboxylic acid is selected from the group consisting of acrylic acids, methacrylic acids, and mixtures of two or more of an acrylic acid and a methacrylic acid. 
     
     
         6 . The polymer composition of  claim 1 , wherein the hydroxyl-containing crosslinking agent comprises a diol. 
     
     
         7 . The polymer composition of  claim 6 , wherein the hydroxyl-containing crosslinking agent comprises 1,4-butanediol. 
     
     
         8 . The polymer composition of  claim 1 , wherein the silane adjuvant comprises a silanc is selected from the group consisting of N-(2-aminoethyl-3-aminopropyl) trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, and combinations of N-(2-aminoethyl-3-aminopropyl) trimethoxysilane and 3-glycidoxypropyl trimethoxysilane, and wherein the silane adjuvant is present in amounts an amount of between about 0.025 and 2.0 wt %, based on the total weight of the polymer composition. 
     
     
         9 . A film comprising the composition of  claim 1 . 
     
     
         10 . An injection molded article comprising the composition of  claim 1 . 
     
     
         11 . A golf ball comprising the composition of  claim 1 . 
     
     
         12 . The polymer composition of  claim 1 , exhibiting an elongation of at least 10%, as determined by ASTM D2990-09. 
     
     
         13 . The polymer composition of  claim 3 , wherein the counter ion is sodium or zinc. 
     
     
         14 . A package comprising the film of  claim 9 . 
     
     
         15 . A film comprising the composition of  claim 2 . 
     
     
         16 . An injection molded article comprising the composition of  claim 2 . 
     
     
         17 . A golf ball comprising the composition of  claim 2 . 
     
     
         18 . A film comprising the composition of  claim 3 . 
     
     
         19 . An injection molded article comprising the composition of  claim 3 . 
     
     
         20 . A golf ball comprising the composition of  claim 3 .