US1921504A - Composite web and method of making the same - Google Patents

Description

Aug. 8, 1933. H. A. CHASE ET AL 1,921,504

COMPOSITE WEB AND METHOD OF MAKING THE SAME Oniginal Filed April 27, 1928 lizmzim Jmy & M6; i Z

li atented Aug. 8, 1933 UNET COMPOSTE WEB AND METHOD OF THE SAME Henry Albert Chase and Harold Ray Titus,

Berlin, N. H.,

assignors to Brown (Company,

Berlin, N. H., a Corporation of Maine Application April 2'7, 1928, Serial No. 273,299 Renewed September 10, 1932 9 Claims.

This invention relates to a composite web which is adapted for a variety of uses, such, for

instance, as filter sheet, medical gauze, or a foundation for various coated or impregnated products. It also relates to a continuous and economical method of making the same, using machinery of the papermaking type.

According to the present invention, we produce a pulp web which is reinforced by fibrous material in the form of a comparatively open, knitted, or woven fabric, or in the form of yarns or threads, with or without lateral tying or filling strands, the term fabric as hereinafter employed in the specification and claims, unless otherwise specified, being intended to mean fibrous material in any one of these forms. The reinforcement of the web may be effected either by felting the pulp fibers on the fabric while it is continuously passing over and being supported on a moving foraminous backing such as Fourdrinier wire,'or else by felting the pulp fibers on the backing and progressively superimposing the fabric on the felting fibers and preferably con-- tinuing felting on the fabric. The composite web is then dried by any suitable method, the product comprising a pulp web reinforced either exteriorly or interiorly by the fabric, the pulp fibers being felted to and entangled in the fabric so that there is little inherent tendency for the pulp to separate therefrom.

The present invention may be applied to advantage when producing a highly absorbent pulp web, the fibers of which exist in a substantially uncompacted but interfelted condition. Such a web may be produced on a paper machine if during the felting and drying of the web it does not undergo substantial compressing or compacting. As heretofore made without such fabric reinforcement, a web of this character is eminently suitable for uses where high absorbency is desired, but it possesses the disadvantage of being difficult to handle without tearing. This disadvantage renders the absorbent web unsuitable for use as a raw material in a process which places it under stress, as it tends to break, even under comparatively low tensions. By reinforcing such a web in accordance with the present invention, it may even be drawn through baths of liquid saturant quite satisfactorily, the resulting product containing a maximum amount of saturant due to its highly absorptive character. For instance, by passing the reinforced web through a rubber-containing bath, e. g., a rubber-benzine solution, rubber latex, or an aqueous dispersion of rubber, a product having very high rubber content and possessing ex- .cellent characteristics for use as an artificial leather is produced. The reinforced web also lends itself well to coating or saturation with thermoplastic materials such as asphalt, or

waxes such as Montan and carnauba, with varnishes or lacquers of the nitrocellulose type, and with other materials.

The present invention will be specifically de-' scribed as applied in the manufacture of, a highly absorbent web, the web being substantially uncompacted during the course of its manufacture, but it is to be understood that the web may, if desired, be more or less compacted, either while wet or after drying. With these and other features and objects in view, the invention may be best understood from the following more detailed description thereof when considered in conjunction with the accompanying drawing, wherein Figures 1 and 2 are diagrammatic and conventional views of one type of web-forming apparatus, respectively illustrating the methods of internally and externally reinforcing the web.

Figure 3 represents a somewhat modified type of apparatus.

Figure 4 illustrates a method of forming a web with a plurality of fabric reinforcements, using an apparatus similar to those shown in Figures 1 and 2.

Figures 5 and 6 are diagrammatic representations of the web-forming end of a paper machine of the Fourdrinier type, illustrating, respectively, methods of internally and externally reinforcing the web.

Figure '7 is an enlarged section through a reinforced web made in accordance with the present invention, showing how the pulp fibers become entangled in the fabric.

Figures 8, 9, 10 and 11 are enlarged sections through various types of reinforced webs which may be produced by the methods of our invention.

Referring in detail first to Figure 1 of the drawing,'1 indicates a cylinder mould which rotates in a pulp suspension maintained in a vat 2, a moving Fourdrinier wire 3 being guided into contact with the unsubmerged portion of the roll and passing around the submerged portion of the mould. The pulp suspension delivered into the vat is pref erably of very dilute consistency, containing, say, 005% to 01% fiber, preferably in an unbeaten condition, especially when a highly absorbent web is desired. A fabric, preferably of an open weave, such as cheesecloth, is shown being unwound from a roll 4 and passing into the pulp suspension and into contact with the wire 3 about the mould at a point somewhat removed from the surface of the pulp suspension. As the wire passes into the pulp suspension and around the mould, a layer of pulp fibers is deposited thereon. As soon as the fabric comes into contact with the wet pulp layer, pulp fibers deposit on the fabric as the water continues to pass into the cylinder mould from which it is removed, so that the fabric lies between two pulp layers the fibers of which are entangled therewith. The wire moves out of the pulp suspension, carrying a wet pulp web reinforced interiorly with a fabric layer as shown in Figure 8. This entangling of the fibers with the fabric is illustrated in Figures '7 and 8, the fabric first having been brought into contact with wet pulp the fibers of which have penetrated thereinto, whereupon felting of other fibers has been produced directly on the opposite face of the fabric fibers penetrating the fabric from that face. To obtain a product of maximum absorbency, the web should be dewatered without a substantial compacting of its fibers.

As shown in Figure 1, this may be accomplished by passing the wire with the wet web thereon around one or more drum dryers 5, the dry web produced being removed from the wire and reeled, and the wire returning to the cylinder mould. If the web is to be reinforced exteriorly, the fabric may be passed into contact with the unsubmerged portion of the cylinder mould, as shown in Figure 2, the pulp fibers being felted on the outer face of the fabric and penetrating the fabric from that face, resulting in a product a section of which is illustrated in Figure 9.

Instead of completely drying the web while on the wire, it may be partially dried while on the wire and then dried to completion after removal therefrom. Such a procedure is illustrated in Figure 3, the web being on the wire while passing over a suction box 6, and over a heating device 7, and then being transferred from the wire and passed around a drum dryer, the wire returning over a guide roll 8 to the cylinder mould.

A web having a plurality of fabric layers spaced apart may also be formed by the method of our invention. This may be done, as shown in Figure 4, by passing a plurality of webs of fabric to the cylinder mould at different levels of submergence, pulp being deposited on each of the fabric layers before the succeeding fabric layer is applied. This method results in a product shown in section in Figure 10, a plurality of spaced layers of fabric 1 being embedded in the pulp web, the fibers of which are more or less entangled in the fabric layers.

Reinforced webs such as hereinbefore described may be produced on paper machines of the Fourdrinier type, by passing the fabric superposed on the Fourdrinier wire and running the pulp out on the fabric to produce a web reinforced exteriorly, or running the pulp out on the wire above and below the fabric, so as to embed the fabric in the pulp. The first-mentioned method is illustrated in Figure 5, the fabric being unwound from a roll and fed through a supply of pulp suspension maintained in a fiow box 9. The fabric is drawn through the pulp suspension by a pair of rolls 10 at the same rate of speed as the rate of travel of a Fourdrinier wire 11 onto which the fabric and pulp discharges through a transverse opening 13 in the box, and

over an apron 14 extending from the lower edge overlying the wire, and the pulp overlying the fabric. The pulp which passes through the opening then felts or deposits on the fabric to produce a web reinforced exteriorly with fabric, as illustrated in Figure 9. According to the second method, the fabric is guided midway of the opening 13, so as to divide the pulp flowing through the opening, one portion of the stream passing under the fabric and felting on the wire, and the other portion passing above the fabric and felting on the fabric. This produces a web reinforced by the fabric between its faces, as illustrated in Figure 8. The wet web may be either partially or completely dried on the Fourdrinier wire, as already described. Where the fabric is woven, as in the case of cheesecloth, webs which are reinforced transversely and longitudinally are produced. All that may be necessary in some cases, however, is to reinforce the web lengitudinally, so that it may be drawn or subjected to longitudinal tension only without breaking.

When this is the case, the web may be reinforced by using strand material such as yarns or threads in place of fabric such as cheesecloth, the strands being arranged in generally parallel relationship while felting of the pulp fibers is being effected. This results in a product such as illustrated in section in Figure 11, the strands of fibrous material being embedded in the web and reinforcing it longitudinally, or of course the strands may be positioned at one face only of the web, in a manner similar to the woven fabric reinforcements shown in Figures 7 and 9.

While fiber of any suitable origin, for instance, sulphite or kraft pulp, may be'employed as a raw material in the production of the web of the present invention, if a high grade absorbent product suitable for use as filter sheet or medical gauze is desired, we preferably use cotton or rag fiber or wood fiber which has been refined to high alpha cellulose content. If the product is to be coated or saturated with rubber or with other materials, it'may be preferable to employ fibers of comparatively high average fiberlength, such as jute, hemp, and manila, owing to the particular physical characteristics which such fibers impart to the product.

Having thus described certain embodiments of this invention, it is evident to those skilled in the art that various changes and modifications might be made therein without departing from the spirit or scope of invention as defined in the appended claims.

What we claim is:

1. A method of making an absorbent reinforced pulp web, which comprises passing a fabric of the nature of cheesecloth over a moving foraminous backing, felting pulp fibers on and into the fabric, and drying the resulting web while maintained in substantially uncompacted condition, thereby keeping the felted bond between the pulp fibers and fabric undisturbed.

2. A method of making an absorbent reinforced pulp web, which comprises passing a fabric of the nature of cheesecloth over a moving Fourdrinier wire, felting pulp fibers on and into the fabric, and drying the resulting web in substantially uncompressed condition while it is supported by the wire, thereby keeping the felted bond between the pulp fibers and fabric undisturbed.

3. A method of making a reinforced pulp web, which comprises felting-the fiber on a foraminous moving backing, progressively superimposing a fabric of the nature of cheesecloth on the felting face of the pulp suspension and after a layer of pulp has been deposited on said wire, passing a porous fabric of the nature of cheesecloth about said mould into contact with said pulp layer to cause pulp to deposit on and to penetrate into the fabric as water continues to pass into the cylinder mould; and drying the composite web in substantially uncompressed condition, therebypreserving unimpaired the union between the pulp and fabric.

5. A method of making a reinforced pulp web, which comprises maintaining a vat of aqueous pulp suspension in which rotates a cylinder mould into which water of the pulp suspension may pass; passing about said mould a Fourdrinier wire on which pulp may deposit While water is passing into the mould; at a point below the surface of the pulp suspension and after a layer of pulp has been deposited on said wire passing a porous fabric of the nature of cheesecloth about said mould into contact with said pulp layer to produce a wet pulp web felted to, and reinforced interiorly with, a fabric layer; and dewatering and drying the reinforced web in substantially pulp suspension in which rotates a cylinder mould; passing about said mould a Fourdrinier wire on which pulp may deposit; at different levels of submergence passing porous webs of fabric of the nature of cheesecloth about the cylinder mould to effect a deposition of pulp on, and felting of pulp to, each of the fabric webs before the succeeding fabric web is applied; and drying the composite web while maintained in substatnially uncompacted condition, thereby keeping the felted bond between the pulp fibers and fabric undisturbed.

'7. An article of manufacture consisting of a web of pulp reinforced by an open, loosely woven textile fabric of the nature of cheesecloth, the pulp fibers having been deposited and felted on and into the fabric from aqueous suspension and having been dried while maintained in substantially the same uncompacted condition and bonded relation with the fabric as deposited from aqueous suspension.

8. An article of manufacture consisting of a web of substantially unbeaten wood pulp reinforced by an open, loosely woven textile fabric of the nature of cheesecloth, the pulp fibers having been deposited and felted on and into the fabric from aqueous suspension and having been dried while maintained in substantially the same uncompacted condition and bonded relation with the fabric as deposited from aqueous suspension.

9. An article of manufacture consisting of a web of substantially unbeaten wood pulp refined to high alpha cellulose content and reinforced by an open, loosely woven textile fabric of the nature of cheesecloth, the pulp fibers having been deposited and felted on and into the fabric from aqueous suspension and having been dried while maintained in substantially the same uncompacted condition and bonded relation with the fabric as deposited from aqueous suspension.

HENRY ALBERT CHASE. HAROLD RAY TITUS.

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