Label Film for a Blow Moulding Method

Abstract

The invention relates to a biaxial oriented film with a microporous layer, comprising a propylene polymer and at least one β-nucleating agent the microporosity of which is generated by conversion of β-crystalline polypropylene on drawing the film and the use thereof for the labelling of containers in blow moulding. The Gurley value for the film is 10,000 to 300,000 Gurley.

1 - 15 . (canceled) 
   
   
       16 . A biaxially-oriented film with microporous layer comprising propylene polymers and at least one β-nucleating agent, wherein the microporosity of said biaxially-oriented film is achieved by transforming β-crystalline polypropylene by stretching said biaxially-oriented film, and wherein said microporous layer has a Gurley value of from 10000 to 300000 sec and forms an outer layer of said biaxially-oriented film. 
   
   
       17 . The biaxially-oriented film of  claim 16 , wherein said microporous layer has a Gurley value of from 30000 to 150000 sec. 
   
   
       18 . The biaxially-oriented film of  claim 17 , wherein the density of said biaxially-oriented film is from 0.3 to 0.85 g/cm 3 . 
   
   
       19 . The biaxially-oriented film of  claim 17 , wherein said microporous layer comprises a propylene homopolymer, a propylene block copolymer, or mixtures thereof. 
   
   
       20 . The biaxially-oriented film of  claim 16 , wherein said microporous layer comprises a mixture of propylene homopolymer and propylene block copolymer in a ratio of from 90:10 to 10:90. 
   
   
       21 . The biaxially-oriented film of  claim 16 , wherein said microporous layer comprises from 0.001 to 5% by weight of β-nucleating agent relative to the weight of said microporous layer. 
   
   
       22 . The biaxially-oriented film of  claim 16 , wherein said nucleating agent is a calcium salt of pimelic acid, a calcium salt of suberic acid, or a carboxamide. 
   
   
       23 . The biaxially-oriented film of  claim 16 , wherein said biaxially-oriented film is manufactured according to one of the stenter methods and the outfeed roller temperature is from 60 to 130° C. 
   
   
       24 . The biaxially-oriented film of  claim 16 , wherein said biaxially-oriented film consists of a single microporous layer. 
   
   
       25 . The biaxially-oriented film of  claim 16 , wherein said biaxially-oriented film is multi-layered and wherein one surface of said microporous layer comprises an additional top layer. 
   
   
       26 . The biaxially-oriented film of  claim 25 , wherein said additional top layer is applied by means of coextrusion, coating, or lamination. 
   
   
       27 . A biaxially-oriented film with microporous layer comprising propylene polymers and at least one β-nucleating agent, wherein the microporosity of said biaxially-oriented film is achieved by transforming β-crystalline polypropylene by stretching said biaxially-oriented film, wherein said microporous layer forms an outer layer of the film, wherein an outer side of said microporous layer further comprises a top layer, and wherein said biaxially-oriented film is prepared by biaxial stretching of an unstretched prefilm with a β-crystalline polypropylene content of 20 to 60%. 
   
   
       28 . A method for manufacturing a labelled container by means of a blow-moulding method, wherein in said method a thermoplastic polymer is extruded through a tubular die as a fusion tube into a two-part mould, wherein a film or at least one film segment is inserted, and through clasps of the two-part mould the fusion tube is squeezed at one end and at the opposite end air is introduced in such a way that the fusion tube is inflated and adapts itself to the mould in such a way that thereby a hollow body is formed and simultaneously the inserted label is applied, wherein said label comprises the biaxially-oriented film of  claim 16  and wherein the microporous layer of said film joins itself to the container. 
   
   
       29 . A labeled contained prepared by the method of  claim 28 . 
   
   
       30 . A method for manufacturing a film with microporous layer, comprising extruding as a single layer or as the outer layer of a multi-layered film a mixture of at least one polypropylene polymer and at least one β-nucleating agent to form a prefilm, extracting and cooling said prefilm on an outfeed roller, and stretching said prefilm in longitudinal and lateral directions, wherein said cooling is performed so that the β-crystalline polypropylene content in said single layer or in said outer layer of a multi-layered film is from 20 to 60% prior to stretching.