US1490362A - Waterproof fiberboard - Google Patents

Description

Patented Apr. 15,19 24.

UNITED STATES PATENT OFFICE.-

ALBERT L. CLAPP, F DANVERS, MASSACHUSETTS, ASSIGNOR T0 BECKWITH MANU- FACTURING COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

WATERPROOF FIBERIBOARD.

No Drawing.

To all whom it may concern:

Be it. known that I. ALBERT L. CLAPP, a citizen of the United States, residing at Danvers, in the county of Essex and State of Massachusetts, have invented new and useful Improvements in \Vaterproof Fiberboard, of which the following is a specification.

This invention has for its object the utilization of material for which there has been no commercial use, namely, box toe waste, i. e, the scraps left after cutting box-toe blanks from a sheet of fibrous material containing bitumens, resins, waxes, or other thermo-plastic stiffening agents, alone or in admixture. It has hitherto been the practice, in the manufacture of box-toes, toform a sheet' of fibrous material, such. as fielt formed either on a felting machine or a paper machine, to impregnate or saturate the sheet with a thermo-plastic compound, adapted to be softened upon the application of moderate heat, and then to ,cut the boxtoe blanks of appropriate size and shape from the sheet, and insome cases to subject such blanks to a calendering operation. Due

' flammability of the solvent, the cost of re-' to the shape of the blanks, there is neces sarily' a wastage of the sheet material due to the formation of scraps and cuttings, for which no use has heretofore been found. Attempt has been made by the use of a solvent to extract the valuable gums, resins or other stiffening agents from'the waste scrap material, but this has proved commer clally to possess little value, due to the incovery, and the other necessary operations which are expensive. Then, again, the stiffening agent usually comprises-several ingredients blended together to impart to the box-toe the desired characteristics, and these ingredients may be varied acording to. thevarying costs thereof. Among these thermo-plastic materials are montan and carnauba wax, common or blown asphalt, rosin and copal-resin, I resin soaps, drying oils, etc., some or all of which, included by the term thermo-plastic compound, are used in varying proportions, to produce a compound or mixture which will readily penetrate the fibrous sheet, soften at a moderate temperature, while not affected by body or solar heat, set rapidly when cold, and impart stiffness and rigidity to the molded toe box. Such compounds are usually characterized Application filed December a, 1922. Serial No. 605,721.

y though they have no sharp or critical melt ing and solidifying points. 7

I have found that it is possible to use such waste box-toe material in the production of a water-repellent fiberboard for a number of uses in the arts, wherein both the fibrous material and the thermo-plastic compound possess great value. Ordinarily the proportion of thermo-plastic compound to fiber by weight is relatively large, and although additional fibrous material is supplied for the manufacture of fiberboard, the thermoplastic compound is suflicient, when coalesced, in the sheet, to furnish the necessary or desirable water-proof or water-repellent qualities.

After much experimentation, I have found that it is possible to disintegrate the boxtoe waste by grinding it while dry in a suitable grinding machine, such as an Abbe grinder. It is desirable from time to time to throw a handful of talc into the grinder to prevent the thermo-plastic compound from sticking to the knives. When disintegrated to a relatively fine dry state, the material is now ready for use.

I place'in a beating engine a quantity of cellulose fiber, such, for example, as chemical wood pulp, or sulphite, or sulphate screenings, waste kraft or manilla paper, or other paper making stock, together with suflicient a relatively short melting point lag,

ably subject the stock to a prolonged beating sufficient to produce a fairly hydrated or slow stock. Then while continuing the beating' operation, I add (say four parts) a quantity of the disintegrated box-toe waste, and thoroughly mix it with the hydrated paper stock until a homogeneous pulpy mass is produced. The stock is now sheeted by any approved papermachine, such as a wet machine, a multi-cylinder machine, or a Fourdrinier machine. When first formed and dried, it is relatively porous, but I now subject the sheet to both heat and pressure, as by .the use of heated rolls, by which the thermo-plastic compound, which is distributed throughout the fibersof the sheet, is fiuxed or softened and coalesced into a state of continuity throughout the sheet, so as to enclose the fibers and protect them against the access of moisture. In the foregoing example, the mucilaginous hydrate on thecellulose fibers and fibrillaa is sufiicient toretain in the pulp those particles of the thermoplastic compound which were freed from adherence to the fibers by the grinding operation, during the forming of the sheet and the removal of water therefrom, but the ex- 40 parts cellulosic stock, and 80 to (50 parts box-toe Waste, by dry weight.

In many cases I regard it as desirable to use some additional device for fixing the thermo-plastic particles on the fibers to prevent their waste with the white water, since I may also thereby reduce the length of the beating and decrease the extent of colloidal hydration. To this end, I add to the stock in the beater and incorporate therein a suitable sizing compoufid, which I then precipitate by a suitable precipitating agent, so that the free particles of thermo-plastic compound are coagulated, carried down and fixed upon the fibers. I employ a rosin size, or silicate of soda, or both, as the sizing compound, and precipitate the same with alum or other suitable precipitant.

As indicating the proportions which may be used, the following will serve as examples, though it will be understood that these proportions may be greatly increased.

Example Example '11.

. 70 parts box-toe waste 30 parts sulphite pulp 10 partsrosm size 2 parts silicate of soda 15 parts alum and pigments or dyes.

Example 111.

2040 parts sulphite pulp, beaten from to 4 hours 80-60 parts box-toe waste.

The final product forms, after subjection to heat and pressure, a hard dense highl water-repellent or water-proof fiberboar which may be molded, and which may be used in the manufacture ofi trunks, containers, automobile flooring, etc., and which lends itself to many other uses in the arts.

What I claim is:

1. A process of making fiberboard which comprises disintegrating box-toe waste having a thermo-plastic compound incorporated therein, forming an aqueous pulp of said disintegrated material together with cellulosic material, and sheeting said pulp on a paper machine.

2. A process of makin fiberboard which comprises disintegrating ioxtoe waste having a thermo-plastic compound incorporated therein, while maintaining said waste in a dry state, pulping said disintegrated material together with cellulosic material and water, and forming said pulp into a sheet.

3. A process of makin fiberboard which comprises disintegrating %OX-t0 waste having a thermo-plastic compound incorporated therein, while maintaining said waste in a dry state, pulping said disintegrated material together with cellulosic material and water, forming said pulp into a sheet, and

subjecting such sheet to heat and pressure to flux and cause the coalescence of the thermoplastic compound.

4. A process of makin fiberboard which comprises disintegrating %)0Xt08 waste having a thermo-plastic compound incorporated therein, beating cellulosic material with water to form a pulp, incorporating the disintegrated waste material together witha sizing compound in said pulp, adding a precipitating agent, and then sheeting the resultant pulpy mass on a paper machine.

5. A process of makin comprises disintegrating ox-toe waste having a thermo-plastic compound incorporated therein, beating cellulosic material with water to form a pulp, incorporating the disintegrated waste material together with a sizing compound in said pulp, adding-a precipitating agent, sheeting the resultant pulpy mass on a paper machine, and finally y heat and ressure fluxing the particles of thermo-plastic compound incorporated in the sheet. v

6. A water-repellant fiberboard comprising cellulosic material, and disintegrated fibrous box:toe waste having a thermo-plastic compound incorporated therein, all with the fibers in felted relation and protected by the said thermo-plastic com ound.

fiberboard which a In testimony whereof I ave aflixed my 7 signature.

ALBERT L. CLAPP.