Treatment of fibrous material
AssigneeKarl Kroyer St. Anne's Limited
InventorsDenis Raymond Hicklin, Derek Graham Walter White, Brian William Attwood
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Abstract
A process for making a multi-ply consolidated dry-formed fibrous web having at least three plies, the outer plies are impregnated with a stiffening agent (e.g. starch) and the intermediate plies are impregnated with a sizing agent (e.g. wax/rosin size) to render them impervious to the stiffening agent. After the web has been consolidated by hot moist pressing, its outer surfaces may be further sized and hot moulded.
Claims15
A method of making a multi-ply consolidated dry-formed essentially cellulosic fibrous web having at least three plies including an outer ply, at least one intermediate ply and a second outer ply, and wherein the intermediate ply or plies is or are impregnated with a sizing agent and in continuous contact with the outer plies, comprising the steps of:
- dry-forming said outer ply, dry forming at least one said intermediate ply and dry forming said second outer ply, including sandwiching the intermediate ply between said outer plies in continuous contact therewith and consolidating the three plies together by hot moist pressing thereof into a self-sustaining multi-ply web, each said dry forming step including laying down the cellulosic fibers as a ply in a dry state, and including adding moisture to the dry laid plies prior to said consolidating step,
- impregnating said outer plies with a stiffening agent to render them stiffer than the intermediate ply or plies,
- and wherein said sizing agent of the intermediate ply or plies has the characteristic of rendering the intermediate ply or plies relatively impervious to the stiffening agent of the outer plies.
A multi-ply consolidated web comprising a pair of outer plies of dry-formed essentially cellulosic fibrous material impregnated with a stiffening agent, and an intermediate ply of said dry-formed essentially cellulosic fibrous material which is impregnated with an agent rendering is relatively impervious to the stiffening agent of the outer plies, said stiffening agent being present in an amount sufficient to render the outer plies stiffer than the intermediate ply, each of said plies having the characteristics of having been dry formed by the laying down of cellulosic fibers thereof as a ply in a dry state followed by consolidation of the plies resulting from hot moist pressing thereof, and said intermediate ply being in continuous contact over both of its surfaces with the two outer plies.
Dependencies are inferred from the claim text.