US2398297A - Shot shell wad - Google Patents

Description

Patented Apr. 9, 1946 UNITED STATES .PATZEI N T OFFICE SHOT SHELL Walter L. Finlay, Fairfield, Conn, assignor to Remington Arms Company, ='Inc.-, Bridgepbrt, Conn., a corporation of Delaware No Drawing. Application May 8, 1942, Serial 'No. 442,229

40laims.

Thisinvention relates, in general, to shot shell wads, and, particularly to an improved material for-wads.

"An object of the invention is to provide an improved material for shot shell wads which is more economical to produce than hair felts and the like.

A further object is to provide a moldable material for wads containing fibers substantially free from water soluble deleterious materials. A further object is to provide a molded wad comprising a coherent body of \lignocellulose fibers and a suitable binder.

The invention lends itself particularly to the method o'f -moldlng wads such as described in the patent to Woodford 2,026,765. According to the patented process, a water suspension is prepared of suitable wad-forming materials which may be an intimate mixture of fibers of varying lengths andsurface characteristics witha granular .filler. Hair, felt, waste cotton, etc., are disclosed as suitable long fibers, and unhydrated wood pulp as a shortfiber. The filler used is-sawdust, wood flour, cork, or other granular material.

More specifically, the present inventionhas its inception ina modificationof the Woodtord proc-' ess wherein a mixture has been used'comprising scrap cattle hair felt, mechanical wood pulp, and a bonding material of such a character that it may be added as discrete particles during the process of manufacture, be filteredout as discrete particles during the laying or melding of the wad-forming material, and then, or subsequently, be gelatinized or otherwise so dispersed as to acquire "adhesive properties. Among such bonding materials, starch was found to be particularly adapted to use in a process in which the wadforming material is laid in a fibr ous stock, the latter consisting specifically of water containing granulated raw starch and substantially 1% of scrap cattle hair felt and mechanical wood .ipulp in suspension.

The terms mechanical wood pulp or mechanical pulp will be understood to mean ungelatinized wood pulp consisting of short, chopped up fibers or fiber bundles, while the term laid, as used, means the formation of a self -sustaining, semicoherent body or mat of the solidand fibrous materials contained in the stock. Such a body or mat is obtained by draining ofi the stock liquid through a screen, as commonly practiced in the paper making industry, or preferably in the manner more fully explained in the above identified Woodford patent wherein -'a iportion of the stock may "be placed in "a wad mold. from which the liquid is drained.

As the liquid is drained oif, a small percentage of the starch particles are filtered out 'of the liquid and substantially uniformly dispersed throughout the fibrous mat, the amount of starch filtered out being governed in general by the porosity of the mat and the fibrillous character of the interlocked fibers. 1

Following the laying or felting 'of the fibrous material, either in a form of a mat or molded article, sufficient heat maybe applied to the material to gelatinize the starch.

Although highly satisfactory shot she'll wads have been produced in the above manner, yet these processes are relatively expensive. This is borne out by the fact that in order tola'y'downa fibrous mat or molded wad of substantially halfinch thickness from stock of 1% fiber suspension, a relatively large volume of water and starch is required of which substantially to of the starch is wasted when the stock liquid is drained away; and {of all the ingredients used in making the wad material, the starch is the most expensive. The necessity for discarding the stock water arises from the fact that the scrap "cattle hair felt almost invariably includes some Water soluble deleterious material and in specific instan'c'e's has been "found to contain substantiall 30% of water soluble dextrine. Thus it happens that by recirculation of the stock, the dextrine rapidly accumulates in the water so that it becomes gummy thereby contributing a gelatinous quality to the "felted'material prior to the mol'd'ing'of the wad, whereby the wad-punches, such as used in the above identified 'Wood'ford process, become dirty and clogged "and the molded wads "them selves are of inferior quality. A further "factor contributing to the 'expensiveness of this process is the relatively high cost of c'attle'hai-r.

The present invention is in the discovery that molded or felted shot shell wads may be produccd at 'considerab'ly less cost and at greater production rates by using lignocellulose'fibers known as Asplund fibers.

The term Asplund'j as used in this specification, shall be understood to designate lignocellulcse fibers obtained by the Asplund defibrillatin'g process which is fully described in United States Patents 2,145,851; 2,008,892 and 2,047,170. These fibers are obtained from wood chips by separating the individual fibers from the fiber bundles in relatively long unbroken lengths, and are distinguishable over other'typesof wood'fibers in that the lignin which, with cellulose, constitutes an essential part of Wood tissue, is not dissolved out of the fiber during the process of defibrillating. The term Asplund shall also be understood to designate lignocellulose fibers known in the trade as Chemical Asplund fibers.

Previous to the Asplund lignocellulose fiber, all wood fibers have been obtained either by mechanical or chemical processes or combinations thereof, whereby the fibers were separated either as broken-up, relatively short lengths or in a degenerated form due to the loss of a substantial quantity of lignin. The Asplund fibers are, however, defibrillated wood fibers having a structure closely resembling the original fibers with more pliability and strength than any wood fibers heretofore made.

The Asplund fibers are particularly adapted to wad materials in that the relatively long unbroken length of the individual fiber is closeto ideal for felted or molded wad processes. These fibers are also substantially free from water soluble materials and hence do not gum up the stock, and, consequently, the stock water remains substantially clean after laying or molding a wad and may be recirculated for subsequent laying or molding processes thus preserving in suspension relatively large quantities of the costly granulated starch.

It has likewise been found that the surface of the Asplund fiber is substantially smooth. This characteristic is of considerable importance in the commercial production of wads since the rate,

of production, in large measure, will be determined by the rate of draining of the stock which relatively thick fibril fuzz, then a mat laid down 7 from such stock would be so slow draining as to preclude the use of such fibers. On the other hand, a mat formed from substantially smooth fibers would normally havefree draining characteristics. as undesirable as excessively slow drainage, since, in the former case, there will be substantially no filtering of starch particles by the matted fibers. However, the drainage characteristics of stock comprising smooth fibers may be controlled to give an optimum rate of drainage attended by proper dispersion of starch throughout the laid mat.

One satisfactory method of forming wad materials from an Asplund fiber stock is to use Asplund fibers which have been partially fibrillated either by a mechanical or chemical process or the combination thereof so that the naturally smooth surface of the fibers will have fibrils formed thereon in an amount commensurate with the optimum drainage and filtering requirements. Thus, when the Asplund stock is drained, starch particles are impeded by the interlaced fibrils and prevented from escaping with the stock water and are filtered out substantially uniformly throughout the fibrous mat.

Inasmuch as the Asplund fibers are normally smooth surfaced, the rate of drainage of the stock and the amount of filtered starch in the mat will be substantially proportional to the degree of fibrillation of the fibers which factor may be varied to accord with individual requirements.

' A specific example of the use of Asplund fibers for making shot shell wads is as follows:

A stock of a concentration of about 1% is prepared from about 60 parts of partially fibrillated Excessively free drainage is, of course, 7

Asplund fibers and 40 parts of a bonding agent, for example, raw granular starch. The stock is beaten to secure uniform dispersion and distribution, but not hydration of the fibrous materials. The prepared stock is then delivered to the laying or molding apparatus which, in the latter case, may be of the form described in the abovementioned patent to Woodford. .Of the 40 parts of bonding agent in suspension in the stock, about 8 parts are filtered out into the laid material by the interlaced fiber fibrils while the remainder is carried away in the stock water.

However, since the Asplund fibers contain no water soluble materials, the stock water is clean and free from any deleterious substances, and, therefore, may be continuously recirculated for successive mat layings 'or moldings with the addition of only that quantity of starch sufllcient to secure the initial concentration.

The wads leaving the molding machine may contain substantial quantities of water and accordingly they are then dried by heat, the starch being colloidally dispersed in situ in the wadmaterial or molded wad during this heat treatment.

While the above method discloses the use of Asplund fibers which have been fibrillated so as to accomplish the proper drainage and filtering necessary to produce wad mats or molded wads, it is also possible to use various mixtures of the substantially smooth Asplund fiber and a fiber or fibers having the necessary fibrillous character.

Fibers having fibrils and sufilciently economical for carrying out the present invention may include such materials as mechanical wood pulp, sulphite screenings, and kraft.

A specific example of the practice of the invention using a mixture of smooth Asplund fibers and fibrillous fibers is as follows:

A stock of a concentration about 1% is prepared from substantially 40 parts of sulphite screenings and 10 parts mechanical pulp and beaten to secure even dispersion but not hydration of the fibrous materials. To this stock is added about 30 parts of smooth Asplund fibers, 10 parts of wood flour and about 60 parts of the bonding agent. The stock is again beaten to secure uniform dispersion and distribution. The molded wad or felted wad material is then formed from this prepared stock in the manner already describedywith only about 10 of the 60 parts of bonding agent being retained in the molded wad.

Other stocks adapted to the practice of the invention as above described, may have substantially the following compositions, after molding:

55 parts Asplund fibers;

'35 parts mechanical wood pulp;

Although starch has been specified as a suitable bonding agent, it will be understood that other materials may be used which are substantially insoluble in neutral water but which, in the presence of alkalies, form colloidal dispersions. ples of such materials are the salts formed by the Examreaction of casein and alkalies, and cellulose glycolic acid, and its salts, particularly the alkali metal salts of which sodium salt is typical. These agents may be added to the stock in the same manner as starch and remain as separate, substantially solid particles in the stock during the laying of the felted or molded wad. However, upon treatment with an alkali such as ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, dimethylamine, trlmethylamine or other low boiling point amines, they are colloidally dispersed. The alkali may be applied to the felted material as a dilute solution either during or subsequent to the laying of the wad forming body.

While the above described stock compositions have been found in practice to produce relatively inexpensive wad material or molded wads of good quality, this invention is not to be considered as limited to the specific materials and operations herein described by way of illustration, since it extends to all equivalent materials and processes falling within the scope of the appended claims, which are to be broadly construed.

What is claimed is:

1. A shot shell wad comprising a resilient cylindrical felted structure coherent under shot shell firing conditions and consisting essentially of fibrillated Asplund fibers interlaced to provide binder segregating interstices and segregated portions of a starch paste binder adhering essentially to the interlaced fibers only of the respective interstices throughout said structure to provide a permeable structure and to hold together said interlaced fibers.

2. A shot shell wad comprising a resilient cylindrical felted structure coherent under shot shell firing conditions and consisting essentially of Asplund fibers and fibrillated kraft, said fibers and fibrillated kraft being interlaced to provide binder segregating interstices and segregated portions of a starch paste binder adhering essentially to the interlaced fibers and kraft only of the respective interstices throughout said structure to provide a permeable structure, said Asplund fibers and fibrillated kraft being held together by the combined action of said interlaced fibers and kraft and the segregated portions of said starch binder.

3. A shot shell wad comprising a resilient individually molded structure coherent under shot shell firing conditions and consisting essentially of fibrillated Asplund fibers interlaced and disposed in a multiplicity of randomly oriented planes throughout said structure to form interstices therein, and a starch paste binder only partially filling said interstices throughout said structure to provide a permeable structure and to hold together said interlaced fibers.

4. A shot shell wad comprising a resilient individually molded structure coherent under shot shell firing conditions and consisting essentially of Asplund fibers and fibrillated kraft interlaced and disposed in a multiplicity of randomly oriented planes throughout said structure to form interstices therein and a starch paste binder only partially filling said interstices throughout said structure to provide a permeable structure, said Asplund fibers and fibrillated kraft being held together by the combined action of said interlaced fibers and kraft and said binder.

. WALTER. L. FINLAY.