Medical multilayer sealant films and methods for producing the same

Abstract

A multilayer sealant film for use in the medical field at least comprises as its innermost layer a first layer comprising at least one resin selected from the group consisting of linear low-density polyethylene, low-density polyethylene, polypropylene and polybutene-1, and a third layer comprising an ethylene-vinyl alcohol copolymer and laminated to the outer side of the first layer with a second layer serving as an adhesive layer and comprising a resin containing, as a main component, at least one of an amorphous polyolefin, adherent polyolefin and ethylene-vinyl acetate copolymer. The ethylene-vinyl alcohol copolymer forming the third layer functions as a barrier for preventing contaminants from migrating from outside of the third layer toward the first layer (innermost layer). Further, it is possible to improve the formability of the multilayer film since the difference in density between the resin for forming the first layer and the resin for forming the second layer is set to be 0.02 g/cm 3 or less.

1 . A medical multilayer sealant film which is a multilayer sealant film having as the innermost layer a first layer comprising at least one resin selected from the group consisting of linear low-density polyethylene, low-density polyethylene, polypropylene and polybutene-1, the sealant film being characterized in that a third layer comprising an ethylene-vinyl alcohol copolymer is laminated to the outer side of the first layer with a second layer serving as an adhesive layer and comprising a resin containing, as a main component, at least one of an amorphous polyolefin, adherent polyolefin and ethylene-vinyl acetate copolymer, wherein the difference in density between the resin constituting the first layer and the resin constituting the second layer is 0.02 g/cm 3  or less.  
     
     
         2 . A sealant film according to    claim 1   , wherein a co-extrusion inflation process is used to form the multilayer film comprising a first layer, a second layer and a third layer, and wherein the lay flat width of the film is set to be 420-1100 mm and the film take-off speed is set to be 7.0-15.0 m/min during formation of the film.  
     
     
         3 . A sealant film as defined in    claim 1    or    2    wherein the first layer comprises linear low-density polyethylene or low-density polyethylene, and the second layer comprises an adherent polyethylene or ethylene-vinyl acetate copolymer.  
     
     
         4 . A sealant film as defined in any one of claims  1  to 3 wherein the first layer has a thickness of 10 to 40 μm, the second layer has a thickness of 5 to 25 μm, and the third layer has a thickness of 10 to 25 μm.  
     
     
         5 . A sealant film as defined in any one of    claims 1    to    4    which is characterized in that a fifth layer comprising at least one resin selected from the group consisting of linear low-density polyethylene, low-density polyethylene, polypropylene and polybutene-1 is laminated to the outer side of the third layer with a fourth layer serving as an adhesive layer and comprising a resin containing, as a main component, at least one of an amorphous polyolefin, adherent polyolefin and ethylene-vinyl acetate copolymer, wherein the difference in density between the resin constituting the forth layer and the resin constituting the fifth layer is 0.02 g/cm 3  or less.  
     
     
         6 . A sealant film as defined in    claim 5    wherein the fourth layer comprises an adherent polyethylene or ethylene-vinyl acetate copolymer, and the fifth layer comprises linear low-density polyethylene or low-density polyethylene.  
     
     
         7 . A sealant film as defined in    claim 5    or    6    wherein the fourth layer has a thickness of 5 to 25 μm, and the fifth layer has a thickness of 10 to 40 μm.  
     
     
         8 . A sealant film as defined in any one of    claims 1    to    7    wherein the film is 50 to 80 μm in overall thickness.  
     
     
         9 . A film for medical containers which comprises as the innermost layer of a film for a medical container a sealant film defined in any one of    claims 1    to    8   .  
     
     
         10 . A film for packaging medical containers which comprises as the innermost layer of a film for packaging a sealant film defined in any one of    claims 1    to    8   .  
     
     
         11 . A film for covering medical containers which comprises at the innermost layer of a film for a cover a sealant film as defined in any one of    claims 1    to    8   .  
     
     
         12 . A product formed from a film as defined in    claim 9   ,    10    or  11 .  
     
     
         13 . A method of producing a medical multilayer sealant film employing a co-extrusion inflation process, the medical multilayer sealant film having, as the innermost layer, a first layer comprising at least one resin selected from the group consisting of linear low-density polyethylene, low-density polyethylene, polypropylene and polybutene-1, and the sealant film being characterized in that a third layer comprising an ethylene-vinyl alcohol copolymer is laminated to the outer side of the first layer with a second layer serving as an adhesive layer and comprising a resin containing, as a main component, at least one of an amorphous polyolefin, adherent polyolefin and ethylene-vinyl acetate copolymer, wherein the difference in density between the resin used for forming the first layer and the resin used for forming the second layer is 0.02 g/cm or less, and wherein the lay flat width of the film is set to be 420 mm-1100 mm and the film take-off speed is set to be 7.0-15.0 m/min during formation of the film