US1889642A - Sized fibrous product and method of and apparatus for producing the same - Google Patents

Description

NOV. 29, 1932. DAVIS 1,889,642

SIZED FIBROUS PRODUCT AND METHOD OF AND APPARATUS FOR PRODUCING THE SAME Filed Jan. 22, 1931 Jkrezg jam 4 J z fiarg awy Jake fmwa 3 50am 0/ J 024772267 18%;,

jive/ fiegz yej Patented Nov. 29, 1932 UNITED STATES PATENT OFFICE GEORGE E. DAVIS, 01 WALTHAM, MASSACHUSETTS SIZED FIBROUB PRODUCT AND METHOD OF AND APPARATUS FOR PRODUCING SAME Application filed January 22, 1931. Serial No. 510,403.

This invention relates to sized fibrous products and a method of and apparatus for producing the same. It is more particularly concerned with the production of such prod- 5 ucts from bulk fiber of suitable origin by a process which involves the sizing or waterproofing of the fibers in such bulk condition before forming the products. While not limited thereto, the. sized or waterproofed 1o bulk fiber is intended more particularly for fabrication into sheets or boards on machincry of the papermaking type.

Heretofore the sizing of bulk fiber has been customarily accomplished while such fiber is suspended in a comparatively large amount of water in the beater engine, the sizing agent being added during or after the beating operation. After the sizing agent was added to the aqueous suspension of fiber,

the agent was precipitated and fixed on the,

fiber by the use of a suitable acid reagent, usually alum. This well-known procedure of beater sizing is quite satisfactory for customary papermaking, but it is entirely ineffective' in those instances where the fiber stock is acid to-begin with and tends to generate a distinctly acid condition in the beater water.' In such latter instances, the size undergoes'precipitation immediately upon con- 0 tact with the beater water, without becoming anchored to the fibers. Rather, the fibers repel the sizing agent, which is hence liberated practically in entirety in free condition in the aqueous medium and is removed along with the white water during sheet formation.

In accordance with the present invention, I apply the sizing to the bulk fibers, in a dry, individualized condition,'wherefore there is no medium surrounding the fibers in which an acid condition can be developed. The sizing may be carried in an aqueous vehicle, but no such excess aqueous vehicle is used as would cause precipitation of free particles of sizing in the vehicle. Rather, the

vehicle is usedin such amount that it can be absorbed by the fibers while the sizing deposits upon the fibers to coat or envelop the same. The sized fiber may then be co- 0 mingled with suificient water to produce an aqueous suspension suitable for sheeting on a paper machine, but there is little tendency for the sizing material to become disattached from-the fibers and appear in free condition in the water. I prefer to spray the sizing material on the fibers while they are temporarily in suspension in a gaseous medium which holds the fibers in the desired separated or individualized condition, in which condition substantially all their surfaces are exposed to contact with the sizing material, es ecially if applied as a fine spray or mist.

he principles of my invention have valuable application in the production from previously-tanned leather scra (e. g., scrap leather) of a sheet or boar eminently satisfactory for making boot and shoe heels. Heretofore, when such leather scrap was used in making a heeling-board, the scrap was beaten in water for a long period, usually eight to twelve hours, to form a ulp. Darin the beatin period, considerab e of the va uable solub e content of the leather, amountin in some cases to as high as 35%, and inclu ing the soluble tanning agent, is leached out or extracted, resultin both in a loss of raw material and in an ultimate sheet which lacks the density, toughness, odor, and other qualities characteristic of leather. In

fact, a board as heretofore made from. only soaked with water and dried. This defect is one which has not heretofore been remedied in a practical way, for the beating of leather scrap to the point where it has been transformed into a pulp causes a highly acid condition in the beater water. Inasmuch as the size should properly be added to the completely pulped leather and at this stage the beater water may have a pH value of 3 or even lower, the contacting of size with the water releases or precipitates the size in a free condition in the water before it has even had an opportunity to get to the fiber. That the sizing effect on the fiber is practically nil in such case will be readily appreciated from the fact that a pH value in the beater water of at least 6 is required to combine the usual aqueous sizes and the pulp stock properly before the addition of a precipitat is capable of being suspended in water to form a pulp, and then sheeted on a wet machine with little, if any beating. The dry, fiufiy mass is then suspended in air as by blowing into an expansion chamber, and a suitable sizing or waterproofing agent is sprayed onto substantially all the surfaces of the suspended fibers. Preferably, an aqueous solution or dispersion of sizing agent from which the agent is precipitable with an acidic substance is used. This type of sizing agent is common and lends itself to easy, inexpensive and effective application. Upon contact with the tanned leather fibers, which are of acidic nature, the sizing agent is precipitated on the fibers and becomes aflixed thereto. The size-encased fibers are resistant to the extraction of their water-soluble content, including tannin, upon subsequent dilution with the amount of water necessary for sheeting on paper machines. The sizing agent may be a solution of rosin size or an aqueous dispersion of wax, asphalt, resin, rubber, or other waterproofing material, stabilized by a soap or other protective colloid which undergoes precipitation by acid."

With the foregoing and other features and objects in view, I shall now describe my invention in conjunction with the accompanying drawing, which shows diagrammatically and conventionally some of the instrumentalities employed for carrying out my process.

'On the accompanying drawing, 1 represents a conduit into which the fluffy mass of finely shredded leather fiber is delivered by a blower 10 from a suitable shredding machine (not shown). The mass offibers is conducted downwardly into a preferably circular expansion chamber 2, in which the fibers are While, they are thus in suspension, they receive a fine mist of sizing material carried in an aqueous vehicle from spray nozzles 3 arranged at spaced intervals inside the chamber near its upper end. The nozzles communicate with flexible hose connections 4 leading to an annular manifold 5, outside the chamber and thence to a valved pipe 6, through which a pump 20 passes the sizing material under the desired pressure from a suitable source of supply (not shown). The sized fibers descend'through the expansion chamber and in their descent the water absorbed by the fibers causes the water-soluble acid materials to diffuse to their surfaces, where precipitation of the size on the fibers progressively takes place, with a simultaneous fixation of the size. The sized fiber may be discharged from the expansion chamber directly into a stufi chest 7 wherein it is diluted with water to the desired consistency and is preferably treated with sufficient additional acidic chemical, such as alum, to ensure the precipitation and fixation of all the size on the fibers. The sized fiber emerges from the expansion chamber as large chunks, for upon receiving a fine spray of the aqueous sizing material, the fibers tend to settle out and condense into a more or less slushy mass. The fibers of the mass are preferably given suflicient time to precipitate and retain the size on their surfaces, as by remaining for some time on an inclined platform 8, on which they slide downwardly and then finally drop into the batch of diluted stock being produced in the chest.

The stock being produced in the chest may be of a consistency of about 5%, some of the water requisite for such consistency having been introduced into the fiber along with the size in the expansion chamber, and some having been added along with the alum to the sized fiber delivered into the chest. Various proportions of sizing agent may be used for waterproofing the fibers, but about 2% to 5% dry size based on the dry weight of fiber is suitable when the finished product is to serve as a heeling-boardi An amount of alum equal to that of the size may be added to the sized fibers to ensure complete precipitation of the size on the fibers. This amount of alum is actually in excess of that required, as the size has already largely undergone precipitation by the action of the acidic content of the leather fibers thereon. In arriving at the 5% stock consistency in the stuff chest, 2000 parts of water must be added for every 100 parts of dry leather fiber. Preferably one-half or less of this amount of water is used along with the size, not only for the reason that it is undesirable to treat the dry, unsized fibers with so much water that there is an aqueous medium surrounding themin which the size is liberated in free condition, but further because some aqueous sizing materials, especially aqueous dispersions of waxes and asphalts, may themselves be unstable upon great dilution and tend to throw out or precipitate the size.

The sized fiber in the stuff chest may be used as such for forming into sheets or boards on a wet machine, so called, but,if desired, slight beating of the fibers may be effected, in order to enhance the formation or feltability of the fibers into a uniform sheet. Lit,- tle, if any, of the soluble constituents of the fibers are lost, for thereason that these constituents have already been sealed by waterproofing material against extraction by water. In fact, unless the water-repellant coatings on the fibers were destroyed, the watersoluble constituents of the fibers cannot be leached out by water; and finely shredded leather, such as I use as a raw material, does not require more than about twenty minutes of light brushing in a beater to yield an excellent pulp for forming into sheets. There would, in fact, be no pointin beating the fibers to such an extent that their water-repellant coatings are destroyed, for the fibers would then have been shortened in length to such an extent that the resulting product would be unsatisfactory for the purposes desired. The sized fiber is pumped from the stuff chest into a cylinder or wet machine, where it is diluted to about 1% and run off into sheets of the'caliper desired for heel lifts. The sheets are then dried, calendered, and finally cut into heel blocks or lifts.

The specific example hereinbefore given may be departed from while still falling within the ambit of the present invention; For instance, along with the leather fibers, fibers of other origins, such as wood ulp, asbestos, wool, etc., may be employed, ut I prefer an all-leather fiber furnish for making heel-board, as in such case the resulting product more nearly simulates a tanned natural leather. So, too, it is possible to apply the waterproofing material to the fiber without an aqueous vehicle, for instance, in a liquid condition brought about by melting the size or by dissolving in suitable volatile solvents. It is distinctly preferable, however, to work with sizing materials carried by an aqueous vehicle and from which the sizing material is precipitated by more contact with an acid substance, as the operations are simple and inexpensive. A fiber sized in bulk, dry condition, as hereinbefore described, may be useful' in connections other than making sheets or boards, for instance, in the fabrication of moulded or pressed articles of any desired shape. So far as I am now aware, my siz ng process has its greatest utility when appl ed to finely shredded, tanned scrap leather 1ntended for conversion into a heeling board.

I claim: :1. A rocess which comprises suspending dry, bul fiber in a gaseous medium, spraying a sizing agent onto the fiber while thus suspended, forming an aqueous stock of the sized fibers, and forming the stock into the desired article.

2. A process which comprises suspending dry, bulk fiber in a gaseous medium, spraying onto the fibers while thus suspended a sizing agent carried by an aqueous vehicle and precipitable from said vehicle by an acid substance, forming an aqueous stock of the sized fiber, treating the stock with an acid substance, and forming the stock into the desired article.

3. A process which comprises finely shreddlng previously tanned leather to form a fluffy mass of dry fiber, suspending the dry fiber 1n air, spraying onto the fiber while thus suspended a sizing material carried by the aqueous Vehicle and precipitable from said yehicle by constituents in said leather, forming an aqueous stock of the sized fiber, and forming the stock into a board.

fl. A process which comprises finely shredding previously tanned leather to form a flufiy mass of dry fiber,vblowing the mass into a chamber to suspend the fiber in air, spraylng onto the fiber while thus suspended a sizmg agent carried by an aqueous vehicle and precipitable from said vehicle by constituents in said leather, forming an aqueous stock of the sized fiber, adding an acid substance to ensure complete precipitation of sald sizing agent on the stock, and forming the stock into a sheet.

5. An aqueous stock comprising previously tanned, substantially unbeaten leather fibers associated with substantially all of their water-soluble content, including tannin, man unextracted condition, and enveloped by a sizing agent.

6. An aqueous stock comprising previouslytanned, substantially unbeaten leather fibers associated with substantially all of their water-soluble content, including tannin, in an unextracted condition, and enveloped by a waterproofing agent precipitated from an aqueous vehicle by (acid constituents in said fibers.

7 An interfelted, sized fiber board, comprising previously tanned, substantially unbeaten leather fibers associated with substantially all of their water-soluble content, including tannin, in an unextracted condition, and enveloped by a sizing a cut.

8. An interfelted, sized ber board, comprising previously tanned, substantially unbeaten leather fibers associated with substantially all of their water-soluble content, including tannin, in an unextracted condition, and enveloped by a waterproofing agent precipitated from an aqueous medium by acid constituents in said fibers.

9. Apparatus of the class described, comprising in combination a cylindrical chamher 0 n at its upper and lower ends, means for b owing a mass of dry, flufi'y fiber into said upper end to suspend the fiber in air at the up er end of said chamber, means in said cham er near its upper end for spraying a sizing material onto the suspended fibers to coat them and to cause their settling, and means for supplying said sizing material to said spraying means under pressure.

In testimony whereof I have afiixed my signature.

GEORGE F. DAVIS.

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