Multilayer high clarity shrink film comprising monovinylarene-conjugated diene copolymer

Abstract

We disclose a shrink film comprising a first layer comprising a monovinylarene-conjugated diene copolymer; a second layer comprising low density polyethylene (LDPE) and linear low density polyethylene (LLDPE); and a third layer comprising a monovinylarene-conjugated diene copolymer; wherein the second layer is disposed between the first layer and the third layer. We also disclose methods of using the shrink film to prepare bundled or fully enclosed groups of objects.

1 . A shrink film, comprising: 
 a first layer comprising a monovinylarene-conjugated diene copolymer;    a second layer comprising low density polyethylene (LDPE) and linear low density polyethylene (LLDPE); and    a third layer comprising a monovinylarene-conjugated diene copolymer;    wherein the second layer is disposed between the first layer and the third layer.    
   
   
       2 . The shrink film of  claim 1 , wherein the first layer and the third layer together comprise from about 10 wt % to about 40 wt % of the shrink film, and the second layer comprises from about 30 wt % to about 80 wt % of the shrink film.  
   
   
       3 . The shrink film of  claim 1 , further comprising a first tie layer between the first layer and the second layer, a second tie layer between the third layer and the second layer, or both.  
   
   
       4 . The shrink film of  claim 3 , wherein the first tie layer comprises an ethylene-vinyl acetate copolymer (EVA) or an anhydride-modified EVA.  
   
   
       5 . The shrink film of  claim 3 , wherein the second tie layer comprises an ethylene-vinyl acetate copolymer (EVA) or an anhydride-modified EVA.  
   
   
       6 . The shrink film of  claim 1 , wherein the monovinylarene-conjugated diene copolymer is a styrene-butadiene block copolymer.  
   
   
       7 . The shrink film of  claim 1 , wherein the first layer, the third layer, or both further comprise polystyrene (PS).  
   
   
       8 . The shrink film of  claim 1 , wherein the first layer, the third layer, or both further comprise an antiblock agent, a slip agent, or both.  
   
   
       9 . The shrink film of  claim 8 , wherein the antiblock agent is a high impact polystyrene (PS).  
   
   
       10 . The shrink film of  claim 1 , wherein the LDPE is a clarity-grade LDPE.  
   
   
       11 . The shrink film of  claim 1 , wherein the LLDPE is a metallocene-catalyzed LLDPE (mLLDPE).  
   
   
       12 . A method of bundling a group of objects, comprising: 
 wrapping the group of objects with a shrink film comprising a first layer comprising a monovinylarene-conjugated diene copolymer; a second layer comprising low density polyethylene (LDPE) and linear low density polyethylene (LLDPE); and a third layer comprising a monovinylarene-conjugated diene copolymer; wherein the second layer is disposed between the first layer and the third layer and the shrink film has a higher shrink in a first direction than in a second direction, to yield a wrapped group of objects, and    heating the wrapped group of objects to a temperature and for a duration sufficient to shrink the shrink film, to yield a bundled group of objects.    
   
   
       13 . The method of  claim 12 , wherein in the shrink film the first layer and the third layer together comprise from about 10 wt % to about 40 wt % of the shrink film, and the second layer comprises from about 30 wt % to about 80 wt % of the shrink film.  
   
   
       14 . The method of  claim 12 , wherein the shrink film further comprises a first tie layer between the first layer and the second layer, a second tie layer between the third layer and the second layer, or both.  
   
   
       15 . The method of  claim 12 , wherein in the shrink film the monovinylarene-conjugated diene copolymer is a styrene-butadiene block copolymer.  
   
   
       16 . A method of fully enclosing a group of objects, comprising: 
 wrapping the group of objects with a shrink film comprising a first layer comprising a monovinylarene-conjugated diene copolymer; a second layer comprising low density polyethylene (LDPE) and linear low density polyethylene (LLDPE); and a third layer comprising a monovinylarene-conjugated diene copolymer; wherein the second layer is disposed between the first layer and the third layer and the shrink film has substantially similar shrink in both a first direction and a second direction, to yield a wrapped group of objects, and    heating the wrapped group of objects to a temperature and for a duration sufficient to shrink the shrink film, to yield a fully enclosed group of objects.    
   
   
       17 . The method of  claim 16 , wherein in the shrink film the first layer and the third layer together comprise from about 10 wt % to about 40 wt % of the shrink film, and the second layer comprises from about 30 wt % to about 80 wt % of the shrink film.  
   
   
       18 . The method of  claim 16 , wherein the shrink film further comprises a first tie layer between the first layer and the second layer, a second tie layer between the third layer and the second layer, or both.  
   
   
       19 . The method of  claim 16 , wherein in the shrink film the monovinylarene-conjugated diene copolymer is a styrene-butadiene block copolymer.