| 摘要 |
1471436 Corrugated paperboard INTERNATIONAL PAPER CO 14 May 1974 [29 May 1973] 21354/74 Heading B5N Corrugated paperboard, e.g. for use for containers, comprising a corrugated medium having at least one liner attached thereto is produced by applying to at least the corrugated medium or to the liner a rapidly collapsible foam of a dispersion or solution of a water resistant resin, a flame retardant, a fire retardant, a mould inhibitor, a fungicide, an insecticide or a mixture thereof, placing the corrugated medium and liner in adhesive contact with each other, heating the resultant composite to complete collapsing of the foam and to complete impregnations of the liner and corrugated medium with the collapsed foam and drying the composite after the completion of the collapse of the foam by further heating. The foam may be applied in a first stage at the time of assembling the corrugated medium and first liner, in a second stage to the exposed fluted single faced corrugated medium and in a third stage to the second liner prior to contact with the single faced corrugated medium. The foam which may also contain a surfactant and a filler, e.g. starch, wood flour or clay, may be produced by blowing air into an aqueous solution or dispersion of the resin or other additives. The water resistant resin may be a ureamelamine- or phenol-formaldehyde resin, polyester, polyamide, epoxy resin, polyvinyl chloride, polyvinylidene chloride, polymethyl methacrylate, butadiene-styrene, acrylonitrile - butadiene - styrene, polyisoprene, polystyrene, polybutadiene, vinyl chloride-vinyl acetate copolymer, ethyl cellulose or cellulose acetate, the fire retardant may be ammonium phosphate or antimony-trioxide, the mould inhibitor may be copper naphthenate and the fungicide may be a zinc salt of methyl-dithio carbamic acid or 2-mercaptobenzothiazole. Suitable adhesives applied to the crests of the fluted medium are starch/urea formaldehyde resin, resorcinol-starch and starch/polyvinyl alcohol adhesives. In Fig. 1 foam from applicator A is applied to liner 2 which is then applied at corrugator 4 to corrugated medium 1 having adhesive applied to the tips of the flutes by applicator 2A. Further foam is applied to the medium by applicator B and the single faced medium heated and dried in oven 5 prior to the application thereto of further adhesive at applicator 6, and a further liner 7 coated with resin by reverse roll applicator C. The double-backed medium is then heated by passage over steam chests 9 and through curing oven 9a and cut into desired lengths at 10. Foam collapse may be accelerated by incorporating a defoaming agent into the paper or by spraying a solution thereof on to the applied foam. |
