Polyolefin additive composition comprising 3,4-dimethyl dibenzylidene sorbitol and p-methyl dibenzylidene sorbitol

Abstract

A specific combination of two different polyolefin clarifying and nucleating agents, namely 3,4-dimethyldibenzylidene sorbitol and p-methyldibenzylidene sorbitol is provided. Such a combination surprisingly provides improved clarification and crystallization temperatures to polypropylene articles and formulations, better than bis-p-methyldibenzylidene sorbitol alone and equivalent or better than 3,4-dimethyldibenzylidene sorbitol. Such a combination of compounds thus permits the utilization of a new additive for the purpose of modifying polyolefin properties, such as polypropylene clarification and nucleation. The inventive combination may be introduced within any polyolefin composition, again preferably polypropylene, which may then be molded into any shape or form. A method of producing a polyolefin plastic utilizing the inventive combination of compounds is also provided.

1 . (canceled)  
     
     
         2 . (canceled)  
     
     
         3 . (canceled)  
     
     
         4 . An additive composition for polyolefins comprising a combination of at least two compounds, comprising: 
 (a) a first compound comprising bis(3,4-dimethybenzylidene) sorbitol; and    (b) a second compound comprising dibenzylidene sorbitol.    
     
     
         5 . The additive composition of  claim 4 , said composition having a ratio of said first compound to said second compound relative to said combination of about 1:1.  
     
     
         6 . The additive composition of  claim 4 , said composition having a ratio of said first compound to said second compound relative to said combination of about 1:3.  
     
     
         7 . A polyolefin, said polyolefin further comprising a nucleating agent composition, said nucleating agent combination composition comprising: 
 (a) a first compound comprising bis(3,4-dimethybenzylidene) sorbitol; and    (b) a second compound comprising dibenzylidene sorbitol.    
     
     
         8 . The polyolefin of  claim 7  wherein said first compound is provided in a concentration relative to said total polyolefin of about 1000 ppm.  
     
     
         9 . The polyolefin of  claim 7  wherein said second compound is provided in a concentration relative to said total polyolefin of about 1000 ppm.  
     
     
         10 . The polyolefin of  claim 7  wherein said first compound is provided in a concentration relative to said total polyolefin of about 500 ppm.  
     
     
         11 . The polyolefin of  claim 7  wherein said second compound is provided in a concentration relative to said total polyolefin of about 1500 ppm.  
     
     
         12 . The polyolefin of  claim 7  wherein said nucleating agent combination composition is provided in a concentration of from about 1000 ppm to about 4000 ppm of said total polyolefin.  
     
     
         13 . The polyolefin of  claim 7  wherein said nucleating agent combination composition is provided in a concentration of from about 1200 ppm to about 3000 ppm of said total polyolefin.  
     
     
         14 . The polyolefin of  claim 7  wherein said nucleating agent combination composition is provided in a concentration of from about 1500 ppm to about 2200 ppm relative to said total polyolefin.  
     
     
         15 . An additive composition for polyolefins comprising a combination of at least two compounds, comprising: 
 (a) a first compound comprising bis(3,4-dimethybenzylidene) sorbitol; and    (b) a second compound comprising dibenzylidene sorbitol; and    (c) wherein the ratio of said first compound to said second compound is in the range between about 1:3 and about 1:1.    
     
     
         16 . A polyolefin article comprising the additive composition of  claim 15 .  
     
     
         17 . The article of  claim 16  wherein said article comprises a random copolymer of polypropylene.  
     
     
         18 . A method of nucleating a polyolefin comprising the steps of: 
 (a) providing an additive nucleating composition comprising at least 1000 ppm of a combination of bis(34-dimethylbenzylidene) sorbitol and dibenzylidene sorbitol;    (b) providing a polyolefin formulation;    (c) mixing said additive nucleating composition of step “a” with the polyolefin formulation of step “b” to form a resultant mixture; and    (d) melting said resultant mixture of step “c” to form a polyolefin having said additive nucleator composition applied therein.    
     
     
         19 . A polyolefin article made by the method of  claim 18 .  
     
     
         20 . A polypropylene article made by the method of  claim 18 .  
     
     
         21 . The method of  claim 18  wherein the ratio of said bis(3,4-dimethylbenzylidene) sorbitol to said dibenzylidene sorbitol is in the range between about 1:3 and about 1:1.