US1739766A - Method of making compressed dehydrated cellulose sheets - Google Patents

Description

Dec. 17, 1929. w, MORRIS 1,739,766

METHOD OF MAKING COMPRESSED DEHYDRATED CELLULOSE SHEETS Filed May 11, 192'? INVENTOR ATTORNEY- paratus used for carrying out my invention.

Patented Dec. 17, 1929 UNITED STATES PATENT OFFICE ALBERT w.- moimis, or SPRINGFIELD, MASSACHUSETTS, AssIeNoE 'ro GEORGE E.

COBLENS, OF NEW YoBKpN. Y?

METHOD OF MAKING COMPRESSED Application filed May 11,

My invention relates to a new and improved method of making and drying articles formed from wood pulp and other species of pulp and a new and improved article made of pulp. One of the objects of my invention is to provide a method whereby articles consisting of wood pulp-or the like may be economically dried and set into any desired shape.

Another object of my invention is to provide a method whereby moisture will be extracted from .the said pulp to an extent sufficient to set the article, by electrical means in contradistinction to the ordinary thermal treatment heretofore utilized.

Another object of myinvention is to provide a molded article made of cellulose such as pulp or the like.

Other objects of my invention will be set forth in the following description and drawings which illustrate a' p referred embodiment thereof, it being understood that the above general statement of the objects of my invention is intended to generally explain the .same and not to limit it in any manner.

Fig. 1 is a sect-ion on the line 1-1 of Fig. 2 and diagrammatically illustrates the ap- Fig. 2 is a plan view of one-half of a cigar holder, this being one of the, articles which can be made according to my invention.

'I-Iei'etofore in making v arious articles from cellulose material such as pulp, such as papercigar cases and the like, it has been customary to mold the moist pulp into the proper shape by means of dies and then to heat the said articles by currents of heated air or the like set. After the pulp has been set until they had been thoroughly dried and set. Heated steam has also been used for this purpose. This treatment was lengthy and expensive and in addition there was always more orx-less difficulty in keeping theshape of the article during the drying process. Cigar cases and other similar articles have a thickness of about of an inch when the is wet and before the article has been and dried, the thicknessthereof is about of an inch.

5 e ;According to my invention, one of the pairs DEHYDBATED CELLULOSE SHEETS 1927/ Serial no. 190,527. I

of wire mesh dies 11 or 12- is placed in contact with a suitable suction die of the kind which is well known to the trade, so that when the suction die and the mesh member are placed in a receptacle containing wood pulp or the like, a layer of the wood pulp is sucked. into the "interstices of the mesh and also forms a] layer coveringathe inner side of the mesh. The two mesh dies 11 and 12 are'then forced towards each other with considerable pressure while these mesh dies 11 and 12 are provided with perforated backing dies which have the same shape. The pressure applied to the backing dies and the mesh dies may be as hi h as two thousand pounds per square inch dependent upon the thickness of the article which is being made so that as much moisture as possible is squeezed out of. the

mate contact between the mesh dies 11 and 12 and the pulp 10 while leaving a layer of pulp between the mesh dies as illustrated in Fig. 1.

The perforated backing dies are then removed and the mesh dies are respectively connected to the positive pole or terminal 13 and to-the negative terminal 14 of the source of electric current.

I prefer that the mesh dies .lland 12 should be made of a material has a relatively high resistance, and which is resistant to oxidation when heated. However, I do not limit myself to any particular metal or alloy for forming said mesh dies.

I likewise have found it desirable to make the mesh dies 11 and 12 of rather coarse mesh.

such as nichrome which responding to 60 cycles per second, although i I do not wish to limit myselfto the constants above specified. Neither do I wish to restrict myself to an alternating current although I have found this superior to a direct current The direct current above mentioned causes the moisture to travel from the interior of the pulp to the cathode sheet. This cathode sheet should be the bottom sheet because the force of gravity will naturally tend to make the water travel downwardly. Observation has shown that the pulp article 10 adjacent the anode sheet 11 dries first and that drops of moisture form adjacent the cathode 12. If desired, the drying of the cathode side can be accelerated by any suitable means such as a by means of said pressure, as'otherwise the efficiency of the operation is greatly lowered.

After the moisture has been substantially re-' moved by the electrical treatment thus mentioned, the pulp article is set so that it retains the predetermined desired shape. It

- isobvious that the members 11 and 12 could be made in a variety of shapes so as to-make or dry articles having a corresponding variety of shapes. The completed article has surface markings corresponding to the membersll and 12. Experience has shown that if an alternating current be supplied to the members 11 and 12, so as to produce a difference of potential between them which is about 118 volts, that drops of water form upon the lower face of the paper, pulp, or the likewhich is being treated. That is, if the currentsupply is temporarily. discontinued drops of water can be-noticedupon the lower face of the sheet of naterial which is being treated. If :the' current supply is discontinned, these drops of, water are quickly reabsorbed by-the porous material.

Since the-sheet of material which is being treated has considerable resistance, especially as more and more moisture is removed therefrom, the passage ofthe current through the sheet of material tends to heat themembers 11 and 12 sothat any moisture which is forced to the surface thereof is vaporized.

, However, as beforestate d, direct heat may be applied to the faces, of thematerial which is being treatedbecause this is more economical than passing an electric current through the high resistances of the sheet of material whlch is being heated, to heat the members" 11 'and'12.

Ho'weveryany heat produced in the members 11 and 12 by means of an electric current,

hasa very high efficiency in vaporizing the moisture at the surface of the sheet of matee ial which is being treated, because. the

:2 bers 11 and 12 are in intimate contact- 1th sa1d material, due to the pressure utilized for forcing the wire mesh into said material. Although I prefer forming the electrodes 11 and 12 of wire mesh, this is not absolutely necessary for the purposes for which my invention may be utilized. For example,

in drying paper it may be desirable to treat the faces of thebody with smooth electrodes made of thin sheets of nichrome metal for example. It will be noted'that the wire mesh dies are placed. close to each other, since a paper cigar case, is formed of thin sheets of cellulose so that enough current can pass through the pulp, or the like to produce the electric osmosis. Likewise the material treated can readily absorb water, and can permit the free passage of water from the interior thereof to the outside faces thereof,

in contradistinction to materials like wood,

.' which are so slightly absorbent that they have an electric current passed through them by means of. liquid electrodes.

I have described a preferred embodiment ofmy invention, but'it is clear that numerous changes and omissions could be made without departing from its spirit.

I claim: k

1. In the art of drying and setting a cellulose body, that step in the art which consists in subjecting the opposite faces of themoist cellulose body to the action of an electric current passing through the said body, while permitting the moisture to freely escape from the said faces of the body. v

2. In the art of drying and setting a moist cellulose body, that step in the art which consists of passing an alternating current through the said body between opposite faces thereof to force the moisture out therefrom, while permitting the said moisture to freely escape from the said faces.

3. In the art of making a compressed dehydrated cellulose sheet, those steps which consist in compressing the wet cellulose materlal to form a sheet while allowing the expressed water to escape from said sheet, and passing an electric current through saidsheet from one face to the other by means of electrodes which have the shape desired for said sheet,

while maintaining s aid electodes in firm contact with said opposite faces to maintain sa1d sheet in desired shape during the dehydration thereof, the moisture being permitted to escape from said sheet during the passage. of

said current to permit said sheet to be-xsufi ficiently dehydrated to become coherent. 4. In the art of making a compressed dehydrated cellulose sheet, those steps WlllCh consist in compressing the wet cellulose material to form a sheet while allowing the expressed water to escape from said sheet. and passmg analternating electric'current thhough said sheet from one face to the other by means of electrodes which .have the shape desired for saidsheet, while maintaining said electrodes firm contact with said opposite faces to maintain said sheet in said desired shape during the dehydration thereof, the moisture being permitted to escape from said sheet during the passage of said alternating current to be sufliciently dehydrated to become coherent.

5. In the art of making a compressed dehydrated cellulose sheet, those steps which consist in compressing the Wet cellulose between a pair of electrodes having openings therein to permit the expressed Water to freely escape, and then passing an electric current through said sheet from one electrode to the other While said electrodes are maintained in intimate contact with the opposite faces of said sheet, moisture being permitted to escape from said opposite faces While the current is passing through said sheet, to. permit said sheet to be sufiiciently dehydrated to become coherent.

In testimony whereof I afiix my signature.

ALBERT W. MORRIS.

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