Polyolefin additive composition comprising 3,4-dimethyl dibenzylidene sorbitol and p-methyl dibenzylidene sorbitol and method of using such composition in a polyolefin

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 - 3 . (canceled)  
   
   
       4 . A polyolefin additive composition comprising a combination of at least two compounds, comprising: 
 (a) a first compound having from about 5 to about 95 percent by weight of the total combination, said first compound comprising bis(3,4-dimethylbenzylidene) sorbitol; and    (b) a second compound having from about 5 to about 95 percent by weight of the total combination, said second compound comprising bis(p-methylbenzylidene) sorbitol.    
   
   
       5 . The polyolefin additive composition of  claim 4 , said composition further comprising: from about 10 to 90 percent bis(3,4-dimethylbenzylidene) sorbitol and from about 10 to about 90 percent bis(p-methylbenzylidene) sorbitol by weight of the total combination.  
   
   
       6 . The polyolefin additive composition of  claim 4  wherein said composition comprises: from about 10 to about 80 percent of bis(3,4-dimethylbenzylidene) sorbitol and from about 20 to 90 percent of bis(p-methylbenzylidene) sorbitol by weight of the total combination.  
   
   
       7 . The polyolefin additive composition of  claim 4  wherein said composition comprises from about 20 to about 50 percent of bis(3,4-dimethylbenzylidene) sorbitol and from about 50 to 80 percent of bis(p-methylbenzylidene) sorbitol by weight of the total combination, said polyolefin comprising polypropylene.  
   
   
       8 . A solid polyolefin article comprising the composition of  claim 4 .  
   
   
       9 . A solid polyolefin article comprising the composition of  claim 5 .  
   
   
       10 . A solid polyolefin article comprising the composition of  claim 6 .  
   
   
       11 . A solid polypropylene article comprising the composition of  claim 7 .  
   
   
       12 . The article of  claim 11  wherein said article comprises a random copolymer of polypropylene.  
   
   
       13 . The solid polyolefin article of  claim 12  wherein said composition further comprises an acid neutralizer.  
   
   
       14 . A solid polyolefin article made of the composition of  claim 4 , said article comprising a random copolymer of polypropylene, wherein said polypropylene provides at least some amount of ethylene content.  
   
   
       15 . A method of nucleating a polyolefin comprising the steps of: 
 (a) providing an additive nucleator composition comprising at least 1000 ppm of an combination of from 5 to 95% of bis(3,4-dimethylbenzylidene) sorbitol and from 5 to 95% of bis(p-methylbenzylidene) sorbitol, such percentages being based upon the total weight of the combination of said compounds within said additive nucleator composition;    (b) providing a polyolefin formulation;    (c) mixing said additive nucleator 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.    
   
   
       16 . The method of  claim 15  wherein said polyolefin comprises polypropylene.  
   
   
       17 . The method of  claim 15  wherein said composition comprises from about 10 to about 80 percent of bis(3,4-dimethylbenzylidene) sorbitol and from about 20 to 90 percent of bis(p-methylbenzylidene) sorbitol by weight of the total combination.  
   
   
       18 . The method of  claim 15  wherein said polyolefin composition comprises a random copolymer of polypropylene, further wherein said composition applied in said method comprises from about 20 to about 50 percent of bis(3,4-dimethylbenzylidene) sorbitol and from about 50 to 80 percent of bis(p-methylbenzylidene) sorbitol by weight of the total combination.  
   
   
       19 . A polyolefin article made by the method of  claim 15 .  
   
   
       20 . A polypropylene article made by the method of  claim 18.