Patent ID: 6030477
Filing Date: 2000-02-29
Classification: B29D,B31F,B32B,D21H,Y10T

Abstract:
A method of making a composite of paper and plastic film, comprising passing into and through the nip of a pair of nip rolls a web of Kraft paper and a web of plastic film of bioriented polyester, extruding a molten plastic impregnating and bonding agent of ethylene acrylic acid copolymer at a temperature of at least 500.degree. F. into the nip between said webs of a thickness such that the combined thickness of the molten plastic, the paper web and the plastic film web passing into the nip are greater than the least dimension of said nip; the porosity of the paper, the moisture content near an inner surface of the paper, the pressure of the nip rolls, and the thickness, temperature and viscosity of said molted plastic agent being such that part of said molten plastic agent impregnates partially into and becomes part of said paper web and a substantial part of the plastic agent extends outwardly of the inner surface of the paper and forms a new solidified surface on which the plastic film is supported and to which it is firmly bonded, wherein about three pounds of the plastic impregnating and bonding agent per thousand square feet is generally uniformly present between said film and the inner surface of the paper, and extracting from the nip rolls said composite consisting of paper at least partially impregnated with the plastic impregnating and bonding agent so as to be inseparable therefrom without destruction of the paper, the new surface of the plastic agent clear of the inner surface of the paper, and the plastic film web supported on and bonded to the new surface of plastic agent clear of the inner surface of the paper, the thickness of the composite being less than the combined thicknesses of the paper web, the extruded layer of molten plastic, and the plastic film web, passing into the nip, and the plastic impregnating and bonding agent being extruded generally uniformly over the area of the composite in an amount of at least six pounds per thousand square feet.