US1675666A - Method of making fiber board - Google Patents

Description

- July 3, 1928. 1,675,666

W. M. SHOEMAKER, JR

METHOD OF MAKING FIBER BOARD Filed Dec. 27, 1926 v 5 Sheets-Sheet l A TTORNEY July 3, 1928.

W. M. SHOEMAKER, JR

METHOD OF MAKING FIBER BOARD Filed Dec 27, 1926 s Sheets-Sheet 2 QOOOOOO II. I T

hawk. 3 WM m $6 l I l l l l I II 11v VENTOR 1 and mHflMema/fer 1/7, W MW A TTORNEY July 3, 1928.

w. M. SHOEMAKER, JR

METHOD OF MAKING FIBER BOARD Filed Dec. 27, 1925 I5 Sheets-Sheet [N VENTOR ATTORNEY li atented July 3, 1928.

UNlTED STATES PATENT OFFICE.

WILLIAM M. SHOEMAKEB, JR., OF KENNETH. SQUARE, PENNSYLVANIA, ASSIGNOB TO NATIONAL VULCANIZED FIBRE COMPANY, 01' WILMINGTON, DELAWARE, A COR- PORATION OF DELAWARE.

' METHOD OF MAKING FIBER BOARD.

Application filed December 27, 1926. Serial No. 157,218.

The present invention relates to the manufacture of fiber sheets or fiber board quite generally known in the trade as vulcanized fiber, in which a plurality of thin sheets of cellulosic material may be united to form a single sheet; or a single sheet may be employed which may be rolled up over a heated drum or cylinder to produce a sheet of the thickness required.

Heretofore in the manufacture of fiber board the practice has been, as far as I am aware, to subject thin sheets preferably of unsized cotton cellulose paper, to the action of a suitable metallic salt such as zinc chloride in solution in water by passing the said sheets through such a solution having a strength of about 70 Baum and at a temperature ranging from ordinary room temperature to about 35 C, and conducting the sheets'from the said solution directly to and between heated drums or cylinders by means of which the said'sheets are subjected to pressure and heat and union thereof effected to form a single sheet.

In the manufacture of fiber boardit is necessary, after the impregnation of the sheets with a suitable solution, usually consisting of a suitable chemical in water, that heat be applied thereto. Heretofore the heated pressure drums or cylinders or other pressure means, between which the sheets havebeen compressed to effect union thereof, have been relied upon for supplying the heat necessary to be applied to the said sheets. By this method the heat is applied directly only to the outer surfaces or sides of the top and bottom plies or sheets of the plurality of sheets being unlted. In

order that there may be no question but that the sheet or sheets which enter into the final product shall have been subjected to the same treatment it is desirable that heat be applied to each sheet separately referably, though not necessarily, to both s1 es thereof sinmltaneously. As a result of so applym the heat and thereby effecting uniformity 0 application of heat to each sheet a product having uniform texture throughout 1s assured.

The general object, therefore, of the present invention is to provide a novel method by the employment of which a plurality of sheets of cellulosic material may be united to form a fiber board or fiber sheet having improved structural characteristics and qualities.

Other and further objects of the invent1on are to provide a novel method by the employment of which both sides of each of a plurality of sheets of cellulosic material WlllCll may be united to form a single sheet may be subjected to the action of heat at a temperature requisite to and for the manufacture of fiber board, or vulcanized fiber as it is generally called in the trade; to provide a novel method wherein and whereby the respective plies orsheets ofcellulosic material are each subjected to the same degree of temperature; to provide a novel method wherein and whereby the plies or sheets which form the interior of the final product shall have been subjected to the same degree of temperature as the sheets forming the outer sides or surfaces thereof; and to provide other improvements as will be set forth hereinafter.

As a result of the application of heat at the temperature required to the separate sheets which are to be united I have discovered that a more satisfactory product may be obtained than has been obtainable .by the employment of the methods heretofore known and employed in the manufacture of fiber board.

'In describing the method embodying my invention it is preferable that reference be made to an ap aratus which may be em ployed for han ling the sheets of cellulosic material and effecting the necessary treatment thereof and the uniting of the same to form relatively thick sheets of fiber boa-rd. Accordingly, therefore, I have invented and designed an apparatus of novel construction whlch may be employed in the carrying out of the method invented by me and to which reference will be made in connection with the description of the said method.

In the accompanying drawings I have illustrated one form of apparatus embodying the novel means invented b me for forming one or a luralit of s eets into fiber board or vu canize fiber and to which I shall refer in detail in the following descri tion.

11 the rawings.

Fig. 1 is a view in side elevation of a portion of a machine or apparatus by the stituting a part of the means for heating able chemical such as zinc chloride or other separately and individually the sheets of cellulosic material. the union of which is to be effected, the said view showing a portion of the heating means in plan; and

Fig. 4 is a transverse sectional view taken on the line 4-4 of Fig 3.

In the drawings I have shown a magazine 10 or supply of plies or sheets of cellulosic material, a tank 11 containing a suitsuitable metallic salt or other chemical in solution in a suitable solvent. such as water, for impregnating the said sheets, a heating means 12 for the application ofheat at the requisite temperature simultaneously to both sides of each of the chemically treated plies or sheets, and a compressing means 13 wherein the plies or sheets are superposed and merged by pressure into a single sheet. This sheet, after the usual treatment to effect removal of the chemical with which the respective sheets were impregnated or saturated and after having been dried, becomes what is known as fiber board or vulcanized fiber. The plies or sheets usually consist of cotton cellulose but may consist of cellulose obtained from other sources and may also consist of a mixture of cellulose obtained from different vegetable sources.

Themagazine 10 preferably is of open frame-construction having journals 1 1 suitably mounted on side bars 14" to rotatably support the rolls 15 of paper (cellulose sheets) which depend in number upon the number of sheets or plies to be used to form the finished product; that is, the fiber board sheet. Thus, if a five-ply material is to be made only five rolls 15 will be used; while if a fifteen-ply material is to be made there will be fifteen rolls 15 in operation.

' The solution 16 gpreferably ofzinc chlo ride or other suitab e metal salt) of suitable strength, say around Baum, in the tank 11 is provided in sufficient quantity to insure the complete immersion of the maximum number of plies or sheets which may be employed. The temperature of the solution as employed may range from ordinary room temperature to a temperature of about 35 C. One end of the tank 11 is of arc shape as shown in order to provide clearance to permit lateral movement of the pivoted spacing guide cage 17 toward the left in Fig. 2 of the drawings, and upwardly to a position above thetank 11 to facilitate the insertion or threading of the plies or sheets 21 bet-ween the spaced guides 18 and20 provided in two series located in two spaced upwardly converging planes, as shown in Fig. 2. Each guide of one series is located in a position horizontally opposite that of the corresponding guide in the other series. After the sheets 21 have been threaded through the cage 17 underneath opposing guides 18 and 20 and said cage is lowered into the tank 11 as shown in Fig. 2 the said sheets, as they travel forward, are held in spaced substantially parallel relation to each other while in and as they pass through the bath or solution 16. The parallel relationship is unimportant but it is important that they be held spaced from each other. It will be noted that the upper plies or sheets 21 remain in the said bath or solution for a shorter period than do the successive lower plies or sheets. It follows, therefore, that the speed of travel or movement of the sheets through the bath or solution must be such as to allow suflicient time for the necessary impregnation of the uppermost sheets. This is a practical matter 2nd may be readily controlled or provided "To provide for the operation of the cage 17 it is mounted upon a swinging frame 22 which includes lifting arms 23 and a chain hoist 24 whereby it can be swung out of and above the bath 16 for the purpose previously.

stated.

In order to effect uniform heating of eachply or sheet 21. after its passage through the bath 16 and prior to the union of the'shcets, the heating means 12 is provided. In its preferred form the said means consists of a plurality of heating units each of which comprises plates 25 and 27 spaced from and in parallel relation to each other to form a wide thin chamber as indicated-in Figs. 2, 3 and 4 of the drawings For supplying a heating medium to the respective chambers formed by the spaced plates 25 and 27 I have provided in each chamber a tubular structure comprising side members 30 and 31 which are connected by cross-wise extending tubes 32 having openings 32' in the opposite sides thereof. For heating the respective units steam is supplied to the pipes of the tubular frame structure of each unit and escapes throughthe'openings in the cross tubes 32 and through openings 33 in the inner sides of the side tubes 30 and 31 into the chamber between the plates 25 and 27 and is condensed so that the said chamber becomes filled with water at a temperature sufficient to supply the heat to be applied to the respective sheets 21 as they travel through the passageways 26 between the adjoining units. The temperature to which the said sheets may be subjected may range from about 38 C to about 93 C. The upper surface of the plate 25 of each unit preferably is slightly convex as shown. As

the respective sheets 21 are conducted through the passageways 26 they contact with the convex surfaces of the plates 25 of the respective units. The adjoining units are located close together so that the spaces 26 through which the sheets travelers quite narrow. The heat, in the construction shown, is applied to the lower sides of the respective sheets as they pass through the passagewt Iys' 26 by conduction from the plates 25 wit which they are in contact, while to the opposite sides thereof heat is applied by radiation from the plates 27 of adjoining units. The plates 27 of adjoining units are so close to the upper sides of the sheets as they travel through the spaces 26 that each side of each sheet is subjected simultaneously to heatat substantially the same temperature. The'sheets being quite thin it follows that the particles thereof are affected in substantially equal degree. The result of this is that the characteristics of therespective sheets are the same or substantially the I same so that when they are combined into a single sheet a product having uniform and improved characteristics and qualities as compared with products as heretofore manufactured is the result.

Although it is preferred to apply heat to both sides of" each sheet as above described, it is to be understood that my invention comprehends the application of heat to one side only of each sheet. When the said sheets are thin it is apparent that such application usually would accomplish the result desired.

In the case of sheets of c'ellulosic material of relatively low absorbtivity usually char-. acterized as hard, it will be found thatupon the passage of the same through the solution the outer portions of the opposite sides thereof will be sufficiently impregnated to cause efficient union thereof upon their passage between the compression cylinders or drums 35 and 36. It maybe that the portions of such sheets betweenthe said outer )ort-ions upon the o iposite sides thereof will I b not be impregnate'c, or only partially impregnated, but such a condition will not interfere with the efficient union of adjoFning sheets. All of the sheets which maybe passed through the solution and thereafter united will have been subjected to identical treatment and will have substantially the same characteristics.

The respective heating units are supported in spaced relation to each other to provide the passageways 26, to which reference has been made, by the interconnection of the tubes (through which the heating medium is supplied to the respective units) between the said units, and the heating'means 12 as a whole is supported by the common supporting frame 34.

In undergoing the treatment as thus far described impregnation of the sheets with the salt solution or other chemical solution in the tank 11 and gelatinization thereof have been effected. They are now in condition and ready to be superposed and subjected to pressure to effect union thereof to formthe product desired, namely. fiber board or vulcanized fiber as it is generally called.

For effecting union of the sheets which" to the pressure means 13 comprising the heated cooperating )ressure drums or cylinders 35 and 36. y reason of the fact that the individual plies or sheets have been subjected already to the action of heat by the heating means 12 it is not necessary that these drums or cylinders 35 and 36 be maintained at as high, a temperature as heretofore has been the practice. The sheets to be united arev conducted over the (lltlil'l or cylinder- 35, around a portion thereof, and between the said drums or cylinders 35 and 36 and thereby subjected to heavy pressure in known manner 'whcreby union thereof is effected to form a sheet having a combined thickness of the united plies or sheets. The sheet'or board formed by the uniting of the said plies or sheets is led away from the pressure drums as indicated at 37 and may be cut into sections of such length as may be desired. These sections then are subjected to the usual treatment to effect removal of the chemical with which the respective sheets were impregnated as they moved or passed through the solution 16 in the tank 11. After the removal of such chemical, usually zinc chloride, the sheets are dried. However, the present invention is not concerned with the treatment of the sheets after they leave the pressure means 13.

In the methods and apparatus heretofore employed in the manufacture of fiber board or vulcanized fiber the thickness of the sheets constituting the final product which might be manufactured has been restricted or limited. Such restriction and limitation h ave been due to the fact that the heated pressure drums or cylinders corresponding to those designated and 36 in the drawings have been relied upon to furnish the heat necessary to be applied to the respective sheets in order that satisfactory union thereof might be effected. As already indicated, when the pressure drums or cylinders were relied upon to supply the required heat the application thereof has been made only to the outer sides of the outer plies. It is apstrictions and limitations because of the application of heat at the required temperature to eachsheet of a- ,plurality of sheets which areto be united prior to the bringing of the same together between the pressure cylinders or drums of the compression means by which union thereof is effected.

An important and essential feature of my invention consists in the application of heat to the respective sheets which are to be united, preferably simultaneouly to both sides of each sheet, after the same has been impregnated with the solution of salt or other chemical 16 and prior to the bringing of the said sheets together and the subjectionof the same topressure within the compression means 13 to effect union thereof. I

While I have illustrated a plurality of plies or sheets treated and united to form a single sheet of 'fiber board it will be under stood that my invention may be employed in the formation of a fiber board sheetlfro'm .a single thin sheet of cellulosic material of proper character by winding the same up onthe drum or cylinder 36 to' obtain the required thickness. The removal of such sheet from the drum or. cylinder ma be effected in known manner by slitting t e same. a

It is to be understood that the invention is not limited to apparatus of the" specific con-- struction illustrated herein and that the-said invention is susceptible of embodiment in apparatus of other forms of construction than that shown, and also that the method invented by me may be practised and carried out by means other than that shown in the present apparatus.

Having thus described my invention, what I claim and desire tosecure by Letters Patent is:

'1. The method of forming a fiber sheet from a plurality of sheets of cellulosic' material, WlllCll consists in impregnating a plurality of said sheets of cellulosic material thereof; a a,

:5.- The method of forming fiber board,

metallic salt in solution to efiect impregnation thereof, thereafter subjecting the respective sheets to heat at the requisite tem- 'perature while holding the said sheets in spaced relation to eachother, and thereaf ter superposingthe said sheets and applylng,

pressure thereto to effect union thereof. A

The method of forming fiber board from a' lurality of sheets of cellulosi'c material, whichcomprises the subjection of the said sheets to the action of'a suitable chemi cal solution in water'to effect impregnation thereof, causing the said sheets to move through a zone of heat at requisite temperature, holding the said sheets while'moving through said zone "in spaced relation with respect each other, thereafter bringing the said'sheets'together, and subjecting the same to pressure to effect union thereof.

4. The method of forming fiber board,

which consists in passing a plurality of sheetsiof cellulosic material through a water solution-of a suitable metallic salt, .con-

ducting the said sheets in spaced relation.

to eachother away from the said solution andgwhile so spaced applying heat at re 'uisite' temperature simultaneously to bot sides of each sheet, and thereafter'brin'ging the said sheets together and ei fecting union which consists in conducting a plurality of 'cellulosic sheets in spaced relationto each other through a solution of zinc chloride,

thereafter supporting saidsheets in spaced relation to each other and applying heat at requisite temperature to each individual sheet to efiect'the necessary gelatinization,

and thereafter bringing the said sheets together and effecting union thereof to form a single sheet. I i

I 6L The method which comprises the-steps of impregnating a web of cellulosic material with a suitable gelatinizing agent, moving said web through a heat zone wherein heat at substantially the same temperature is applied simultaneously to both sides thereof,

and laminating said web, the steps being performed successively and continuously.

Signed at Wilmington, county of New Castle, State of Delaware, this 23rd day of December, 1926. I

WILLIAM M. "SHOEMAKER, JR.

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