Soft flame-resistant winding film

Abstract

Halogen-free, flame-retardant winding film made of polypropylene copolymers, useful for wrapping ventilation lines in air conditioning units, wires or cables and for bundling, insulating, marking, sealing or protecting.

1 . A winding film of polypropylene copolymer, having a thickness of 30 to 180 μm, wherein 
 the force in machine direction at 1% elongation has a value of 0.6 to 4 N/cm and    the force at 100% elongation has a value of 2 to 20 N/cm,    the crystallite melting point of the polypropylene copolymer is less than 166° C., and    the fraction of flame retardant is at least 40 phr.    
   
   
       2 . The winding film of  claim 1 , wherein 
 the thickness of the winding film is 50 to 150 μm,    the force in machine direction at 1% elongation is 1 to 3 N/cm and/or    the force at 100% elongation is 3 to 10 N/cm.    
   
   
       3 . The winding of  claim 1  wherein 
 the winding film comprises at least one polypropylene copolymer    having a flexural modulus of less than 500 MPa,    and/or    having a crystallite melting point of below 148° C.    
   
   
       4 . The winding film of  claim 1 , wherein the polypropylene copolymer is produced in a process in which a PP homopolymer or random PP copolymer is further reacted with ethylene and propylene.  
   
   
       5 . The winding film of  claim 1 , wherein said winding film is free from red phosphorus.  
   
   
       6 . The winding film of  claim 1 , wherein said winding film has on one or both sides a layer of adhesive, which is based on polyisoprene, ethylene-vinyl acetate copolymer and/or polyacrylate, and 
 optionally has a primer layer between film and adhesive layer,    the amount of adhesive in the adhesive layer being 10 to 40 g/m 2 ,    the bond strength to steel being 1.5 to 3 N/cm,    the unwind force being 1.2 to 6.0 N/cm at 300 mm/min unwind speed, and/or    the holding power being more than 150 min.    
   
   
       7 . The winding film of  claim 1  comprising a solvent-free pressure-sensitive adhesive which is produced by coextrusion, melt coating or dispersion coating, said adhesive being joined to the surface of the carrier film by means of flame or corona pretreatment or of an adhesion promoter layer which is applied by coextrusion or coating.  
   
   
       8 . The winding film of  claim 1 , wherein the flame-retardant filler is added at 70 to 200 phr, 
 and is a magnesium hydroxide.    
   
   
       9 . The winding film of  claim 1 , wherein the backing film, adhesive or any other layer of the winding film comprises a carbon black pigment in an amount of at least 5 phr, the carbon black having a pH of 6 to 8.  
   
   
       10 . The winding film of  claim 1 , wherein said winding film is plasticizer-free or the plasticizer content is so low that the fogging number is above 90%.  
   
   
       11 . A process for producing the winding film of  claim 1 , wherein 
 the compounding is performed in a kneader or extruder so thoroughly that the film manufactured from the compound achieves a breakdown voltage of at least 3 kV/100 μm,    the flame-retardant filler is added not all at once when producing the compound, but instead in at least two portions, and/or    the compound is supplied as a melt without an intermediate stage in solid form to the operation of film production by extrusion or calendering.    
   
   
       12 . A process for producing the winding film of  claim 1  by 
 calender processing, in which case the melt index of the polypropylene copolymer is below 5 g/10 min,    and/or    extrusion processing, in which case the melt index of the polypropylene copolymer is between 1 and 20 g/10 min.    
   
   
       13 . A process for producing the winding film of  claim 1 , wherein 
 the winding film is wound to logs, which then, to increase the unwind force, are heat-treated and subsequently slit into rolls, the unwind force of the material thus produced at 300 mm/min being higher by at least 50% than without such a measure, or    the winding film, for the purpose of increasing the unwind force, is subjected to a flame or corona treatment or is provided with a polar coextrusion layer and is subsequently processed into rolls, the unwind force of the material thus produced at 300 mm/min being higher by at least 50% than without such a measure, or    the winding film is slit by a process which leads, as a result of rough slit edges, to easier hand tearability, the breaking elongation of the winding-film rolls thus slit being lower by at least 30% than in the case of slitting with sharp blades,    the winding film is slit by a process which leads, as a result of rough slit edges, to easier hand tearability, the breaking elongation of the winding-film rolls thus slit being in the range from 200 to 500%,    the winding film is slit on an automatic slitter with defined knife advancement speed,    the winding film is wound on a core with an inside diameter of 30 to 40 mm.    
   
   
       14 . A method for bundling, protecting, labeling, insulating or sealing ventilation pipes or wires or cables and for sheathing cable harnesses in vehicles or field coils for picture tubes which compress s bundling, protecting, labeling, insulating, s aling or sheathing same with the winding film of  claim 1.