Conformable and die-cuttable biaxially oriented films and labelstocks

Abstract

This invention relates to die-cuttable stretch oriented films wherein the tensile modulus of the film in the machine direction is greater than the tensile modulus in the cross direction and the tensile modulus in the cross direction is about 150,000 psi or less. The oriented films are useful in particular for preparing adhesive containing labelstock for use in adhesive labels.

1 . A die-cuttable, stretch-oriented multilayer film comprising 
 (A) a base layer having an upper surface and a lower surface, and comprising polyethylene having a density of about 0.940 g/cm 3  or less, a propylene homopolymer or copolymer, or mixtures thereof wherein the base layer is free of copolymers of ethylene with an ethylenically unsaturated carboxylic acid or ester, and    (B) a first skin layer of a thermoplastic polymer bonded to the upper surface of the base layer, wherein the tensile modulus of the multilayer film in the machine direction is greater than the tensile modulus in the cross direction, and the tensile modulus in the cross direction is about 150,000 psi or less.    
     
     
         2 . The film of  claim 1  wherein the base layer is free of inert particulate filler.  
     
     
         3 . The multilayer film of  claim 1  wherein the base layer comprises a propylene copolymer.  
     
     
         4 . The multilayer film of  claim 1  wherein the base layer comprises a propylene copolymer which is a copolymer of propylene and up to about 40% by weight of at least one α-olefin selected from ethylene and α-olefins containing from 4 to about 8 carbon atoms.  
     
     
         5 . The film of  claim 4  wherein the α-olefin is ethylene or 1-butene.  
     
     
         6 . The multilayer film of  claim 1  wherein the base layer comprises polyethylene having a density of from about 0.890 to about 0.925 g/cm 3 .  
     
     
         7 . The multilayer film of  claim 1  wherein the first skin layer (B) contains inert particulate filler.  
     
     
         8 . The multilayer film of  claim 1  wherein the first skin layer (B) is free of inert particulate filler.  
     
     
         9 . The multilayer film of  claim 1  having a haze of less than 10%.  
     
     
         10 . The multilayer film of  claim 1  having a haze of less than 6%.  
     
     
         11 . The multilayer film of  claim 1  wherein the first skin layer comprises at least one polyolefin, polyamide, polystyrene, polystyrene-butadiene, polyester, polyester copolymer, polyurethane, polysulfone, polyvinylidene chloride, styrene-maleic anhydride copolymer, styrene acrylonitrile copolymer, ionomer based on sodium or zinc salts of ethylene methacrylic acid, polymethyl methacrylate, cellulosic, fluoroplastic, acrylic polymer and copolymer, polycarbonate, polyacrylonitrile, ethylene-vinyl acetate copolymer, and mixtures thereof.  
     
     
         12 . The multilayer film of  claim 1  wherein the base layer and the first skin layer are formed by coextrusion.  
     
     
         13 . The multilayer film of  claim 1  wherein the stretch-orientation in the machine direction is greater than the orientation in the cross direction by at least 10%.  
     
     
         14 . The multilayer film of  claim 1  which has been oriented in the machine direction at a stretch ratio of from about 5:1 to about 10:1.  
     
     
         15 . The multilayer film of  claim 1  wherein the base layer or first skin layer, or both, also contain a nucleating agent.  
     
     
         16 . The multilayer film of  claim 1  containing a second skin layer bonded to the lower surface of the base layer.  
     
     
         17 . The multilayer film of  claim 16  wherein the composition of the second skin layer is different from the composition of the first skin layer.  
     
     
         18 . The multilayer film of  claim 1  having a Gurley stiffness in the machine direction of from about 10 to about 50.  
     
     
         19 . The multilayer film of  claim 1  having an overall thickness of from about 2 to about 3 mils.  
     
     
         20 . The multilayer film of  claim 1  wherein the film has been biaxially stretch-oriented and heat set.  
     
     
         21 . The multilayer film of  claim 1  wherein the multilayer film has been stretch oriented in the machine direction at a ratio of from about 9:1 to about 10:1, and in the cross direction at a ratio of from greater than 1:1 to about 3:1.  
     
     
         22 . The multilayer film of  claim 1  having a friction energy of less than 120.  
     
     
         23 . The multilayer film of  claim 1  having a friction energy of less than 80.  
     
     
         24 . The multilayer film of  claim 1  having an overall thickness of from 1 to about 3.5 mils.  
     
     
         25 . The multilayer film of  claim 1  wherein the film has been stretched in the cross direction at a ratio of from greater than 1:1 up to about 5:1.  
     
     
         26 . The film of  claim 1  wherein the biaxially oriented film is prepared by a simultaneous biaxial orientation process.  
     
     
         27 . A die-cuttable, biaxially stretch-oriented multilayer film comprising 
 (A) a base layer having an upper surface and a lower surface, and comprising polyethylene having a density of from about 0.940 g/cm 3  or less, a propylene polymer or copolymer, or mixtures thereof wherein the base layer is free of copolymers of ethylene with an ethylenically unsaturated carboxylic acid or ester, and    (B) a first skin layer of a thermoplastic polymer bonded to the upper surface of the base layer, wherein the stretch-orientation of the multilayer film in the machine direction is greater than the stretch-orientation in the cross direction by at least 10%, and the tensile modulus of the multilayer film in the cross direction is 150,000 psi or less.    
     
     
         28 . The film of  claim 27  wherein the stretch-orientation in the machine direction is greater than the stretch-orientation in the cross direction by at least about 20%.  
     
     
         29 . The film of  claim 27  wherein the film has been stretched in the machine direction at a ratio of from about 5:1 to about 10:1.  
     
     
         30 . The film of  claim 27  wherein the base layer comprises a copolymer of propylene and up to about 40% by weight of at least one α-olefin selected from ethylene and α-olefins containing from 4 to about 8 carbon atoms.  
     
     
         31 . The film of  claim 27  wherein the base layer comprises a polyethylene having a density of from about 0.890 to about 0.925 g/cm 3 .  
     
     
         32 . The multilayer film of  claim 27  having an overall thickness of from 1 to about 3.5 mils.  
     
     
         33 . The multilayer film of  claim 27  wherein the film has been stretched in the cross direction at a ratio of from greater than 1:1 up to about 5:1.  
     
     
         34 . The multilayer film of  claim 27  having a haze of less than 10%.  
     
     
         35 . The multilayer film of  claim 27  wherein the biaxially oriented film is prepared by a simultaneous biaxial orientation process.  
     
     
         36 . A die-cuttable, stretch-oriented multilayer film having an overall thickness of from about 1 mil to about 3.5 mils and comprising 
 (A) a base layer having an upper surface and a lower surface, and comprising polyethylene having a density of about 0.940 g/cm 3  or less, a propylene homopolymer or copolymer, or mixtures thereof wherein the base layer is free of copolymers of ethylene with an ethylenically unsaturated carboxylic acid or ester, and    (B) a first skin layer of a thermoplastic polymer bonded to the upper surface of the base layer, wherein the tensile modulus of the multilayer film in the machine direction is greater than the tensile modulus in the cross direction, the tensile modulus in the cross direction is about 150,000 psi or less, the multilayer film has been oriented in the machine direction at a stretch ratio of from about 5:1 to about 10:1 and in cross-direction at a stretch ratio of from greater than 1:1 up to about 5:1 provided the stretch ratio in the cross direction is less than the stretch ratio in the machine direction, and the film is free of copolymers of ethylene with an ethylenically unsaturated carboxylic acid or ester.    
     
     
         37 . A die-cuttable, biaxially stretch-oriented multilayer film having an overall thickness of from about 1 mil to about 3.5 mils and comprising 
 (A) a base layer having an upper surface and a lower surface, and comprising polyethylene having a density of from about 0.940 g/cm 3  or less, a propylene polymer or copolymer, or mixtures thereof wherein the base layer is free of copolymers of ethylene with an ethylenically unsaturated carboxylic acid or ester, and    (B) a first skin layer of a thermoplastic polymer bonded to the upper surface of the base layer, wherein the stretch-orientation of the multilayer film in the machine direction is greater than the stretch-orientation in the cross direction by at least 10%, the tensile modulus of the multilayer film in the cross direction is 150,000 psi or less, the multilayer film has been oriented in the machine direction at a stretch ratio of from about 5:1 to about 10:1 and in cross-direction at a stretch ratio of from greater than 1:1 up to about 5:1, and the film is free of copolymers of ethylene with an ethylenically unsaturated carboxylic acid or ester.    
     
     
         38 . A die-cuttable, biaxially stretch oriented monolayer film comprising at least one polyolefin wherein the film has been stretch oriented in the machine direction at a stretch ratio of about 9:1 to about 10:1, and in the cross direction at a stretch ratio of from greater than 1:1 to about 3:1.  
     
     
         39 . The film of  claim 38  wherein the stretch ratio in the cross direction is less than 2:1.  
     
     
         40 . The film of  claim 38  wherein the film comprises, polyethylene, a propylene polymer or copolymer, or mixtures thereof.  
     
     
         41 . The film of  claim 38  wherein the film comprises a copolymer or propylene and ethylene or at least one a-olefin containing from 4 to about 8 carbon atoms.  
     
     
         42 . A die-cuttable, stretch oriented multilayer film comprising 
 (A) a base layer having an upper surface and a lower surface, and comprising at least one polyolefin,    (B) a first skin layer of thermoplastic polymers bonded to the upper surface of the base layer wherein the multilayer film has been stretch oriented in the machine direction at a stretch ratio of from 9:1 to about 10:1, and in the cross direction at a stretch ratio of greater than 1:1 to about 3:1.    
     
     
         43 . The multilayer film of  claim 42  wherein the multilayer film has been stretch oriented in the cross direction at a ratio of less than 2:1.