Processing aids for enhanced machine direction orientation rates and property enhancement of polyolefin films using hydrocarbon waxes

Abstract

The present invention disclose a method for the orientation of a high density polyethylene (“HDPE”) film. The process of the invention comprises forming a HDPE-wax mixture by adding to a HDPE batch a normally solid hydrocarbon wax. The HDPE-wax mixture is subsequently stretched into a film at an orientation temperature below the film's melt temperature. The hydrocarbon wax is characterized by having a drop point equal to or lower than the melting point of the HDPE film. The present invention also provides a film made by the process of the invention and a master batch thereof.

1 - 11 . (canceled)  
     
     
         12 . A substantially microvoid-free oriented HDPE film comprising: 
 a) HDPE having a density from 0.93 to 0.965 g/cm 3 , and    b) a hydrocarbon wax in an amount of about 0.02% to about 1% of the weight of the HDPE film,    wherein the hydrocarbon wax has a drop point below the temperature at which said film becomes oriented and said HDPE film has a draw ratio that is greater than 3.    
     
     
         13 . The film of  claim 12  wherein the hydrocarbon waxes are polyethylene waxes, polypropylene waxes, micro-crystalline waxes, and mixtures thereof.  
     
     
         14 . The film of  claim 12 , wherein said hydrocarbon wax is selected from hydrocarbon waxes having drop points below 170° C.  
     
     
         15 . The film of  claim 12  wherein said hydrocarbon wax is selected from hydrocarbon waxs having drop points between 60° C. and 170° C.  
     
     
         16 . The film of  claim 12  wherein said hydrocarbon wax has a molecular weight between about 500 and 5000.  
     
     
         17 . The film of  claim 12  wherein said hydrocarbon wax has a molecular weight between about 1000 and 4000.  
     
     
         18 . The film of  claim 12  wherein said hydrocarbon wax is described by Formula I or branched isomers of Formula I:  
         CH 3 (CH 2 ) n CH 3    I  
       where n is from about 30 to about 360.  
     
     
         19 . The film of  claim 12  wherein said orientation temperature is below melting temperature of the film.  
     
     
         20 . A master batch for addition to HDPE to increase the amount or rate of stretch without breakage or stretch resonance or to decrease the frequency of breakage at a given amount and rate of stretch, said master batch comprising HDPE or a mixture of HDPE and another polyethylene homo- or co-polymer of lower density, and from 1 to about 6 weight percent of a normally solid hydrocarbon wax having a drop point less than or equal to 170° C.  
     
     
         21 . The match batch of  claim 20  wherein the hydrocarbon waxes are polyethylene waxes, polypropylene waxes, micro-crystalline waxes, and mixtures thereof.  
     
     
         22 . The master batch of  claim 20  wherein said hydrocarbon wax is described by Formula I or branched isomers of Formula I:  
         CH 3 (CH 2 ) n CH 3    I  
       where n is from about 30 to about 360.