Document RaLd5MdvvEzVpJbnNRbVLjrmz

FILE NAME: DuPont - Remington (DRM) DATE: 1966 Sept 6 DOC#: DRM001 DOCUMENT DESCRIPTION: Patent - Cartridge Wad and Process for the Manufacture Thereof U nited States Patent Office Patented Se3pt,2. 760, ,1697616 1 2 eral. Asbestos dust, when added to wood dust, retards 3,270,671 explosion and burning. CARTRIDGE WAD AND PROCESS FOR THE Varying compositions of asbestos were mixed with vary MANUFACTURE THEREOF ing quantities of wood flour, "Silvacon" (bark fibre), and Benjamin K. Daubenspeck and Edward A. Rickey, Strat ford, Conn., assignors to Remington Arms Company, 5 wood fiber with varying quantities of binder to successfully .Inc., Bridgeport, Conn., a corporation of Delaware make basewads by using the dry molding process. An No Drawing. Filed Apr. 29, 1965, Ser. No. 452,007 important consideration in limiting the amount of asbestos 7 Claims. (Cl. 102--95) is the weight factor since various functional problems including shell ejection are encountered when too great a This application is a continuation-in-part of copending 10 quantity of relatively heavy asbestos is used. application Serial Number 211,108, filed July 19, 1962, In general, it was found that all ligneous cellulose mate now abandoned. rials are suitable for use as filler materials with asbestos This invention relates, in general, to shot shell wads, fibers. Such synthetic materials as plastic flour (phenol- and, particularly to an improved combination of materials ics), cellulose acetate, polyvinyl alcohol, and polyvinyl for wads. 15 acetate also can be prepared in fibrous form and used as An object of the invention is to provide an improved filler material with asbestos and still be compatible with cartridge wad which is practical and economical to pro the wax binders. duce. It was found that mierocrystalline wax or paraffin or Another object of the invention is to provide an im blends of both with an additive to add strength and re- proved molded cartridge wad having fire and explosion 20 siliency thereto (e.g. butyl rubber) could satisfactorily resisting characteristics. be used as a binder, the exact composition depending on Other objects will be apparent from reading the speci the product desired and the manufacturing circumstances fication and the appended claims. involved. Thus, microcrystalline wax is very plastic at The following discussion will refer mostly to the manu about 100 F. and is a source of some manufacturing facture of molded basewads. However, it must be ap 25 problems at this temperature. Paraffin wax is hard and preciated that the discussion is not intended to be limited brittle and may exhibit some objectionable fracturing char to basewads only. acteristics on firing. The ultimate, of course, is to find Although there are various processes of making base a formula which has the best compressibility characteris wads, most basewads which are made today are made by tics and which is not sensitive to manufacturing condi- either a convolute wound process whereby a strip of 30 tions. paper is wound continuously to form the wad or a wet In general, a wax binder would be suitable if the melt process whereby the wads are molded from a fibrous ing point was not substantially lower than about 120 slurry. One of the main disadvantages of the wet proc F. and not substantially greater than about 200 F. ess, however, is that the wads made by this process are (ASTM Test D127-49) and if its hardness or needle. variable and difficult to control. The wound basewad, 35 penetration was between about 5 to about 100 tenths of- on the other hand, is more expensive and has a serious a millimeter at 77 F. and under a 100 gram load (ASTM deficiency in that its gas-sealing properties are poor. Test D1321-57T). Some manufacturers of wound basewads find it necessary A preferred composition which can be utilized in mak to place an overlay over the wound basewads to seal ing basewads by the cold-dry molding process comprises the gas. This dual construction, however, is more ex 40 about: pensive and has functional problems in that the overlay is not adequately fastened and sometimes comes loose in 40% asbestos; 60% wood fiber; firing the shell. A leaking basewad is objectionable be 8% of microcrystalline wax by weight of the above mix cause of its hard extraction, especially with steel or alumi , _ lure of asbestos and wood fiber. num heads and poor reloading characteristics. 45 The gas-sealing ability of the present dry-mix cold- However, it must be appreciated that the preferred molded basewads is in itself an important improvement in percentages are not limiting in the exercise of the pres the art. ent invention. For example, basewads can be produced In the present new process, low cost fibrous materials of 100% asbestos plus binder or 100% wood fiber plus are blended dry, and adhesive material is added, and the 50 binder. Obviously, at these extremes, it will be neces completed dry free-flowing mix is molded directly into sary to sacrifice various physical characteristics which wads with no further treatment required. may make the wads unacceptable for various -types of Various combinations of biddable fibrous materials were shot-shell use. It has been found that acceptable base tried in order to find a combination of materials which wads for most general uses can be produced by varying would have the necessary physical characteristics which 55 the asbestos not substantially less than 30%' and not sub would permit the dry-mixed material to be molded di stantially more than 60%. Conversely, the wood fiber rectly into the completed wad in one step. In addition to or whatever other filler material is used can be varied the characteristics which would permit molding, the mix from not substantially less than 40% and not substan ture also had to have sufficient strength and other physical tially more than 70%. Finally, the binder, e.g., micro- characteristics to be used as a shot shell basewad. 60 crystalline wax, can be present in an amount equal to It was found that asbestos, not previously used in base 5-15% of the weight of the bindable fibrous materials. wads construction, had the necessary characteristics which permitted its use in this process. First of all, asbestos Process flows readily so that it can be controlled to plus or minus 5 Assuming that the fibrous bindable material is to be grains--an important consideration in basewads where the 65 the preferred mixture, i.e., asbestos and wood fiber, this weight must be carefully regulated. Secondly, asbestos mixture is blended in a ribbon mixer and the mixture is readily compressible so that in a short molding time, air is heated to a temperature of about 120 F.-200 F., is removed and the wad will hold its dimensions. Fur although the preferred range is about 180 F.-200 F. thermore, asbestos has good strength qualities, is a natural Molten microcrystalline wax or a blend thereof is -then binder, is cheap and available, and is stable in heat, mois 70 sprayed on the hot fibrous mixture and the mixture and ture, or corrosive atmospheres. Finally, asbestos is a binder blended. It is possible to add the binder with well-known non-combustible and chemically resistant min- the original fibers, but spraying the molten adhesive on ,3 270,071 3 4 the pre-blended fibers appears to give a more uniform ferred to another ribbon mixer where it is cooled and mixture. . sufficient water added to bring the moisture content to As mentioned above, the preferred range to which about 4- 6V2 percent. _ the fibrous mixture is heated is about 180 F.-200 F. As in the first process, in general all ligneous cellulose However, the mixture can be heated above 200 F. with 5 materials are suitable as filler materials with asbestos a corresponding result that more moisture is driven out fibers. Such synthetic materials as plastic flour (pheno- of the mixture, which moisture must be replaced before lics); cellulose acetate; polyvinyl alcohol; and polyvinyl the final molding of the wad. The temperature is kept acetate also can be prepared in fibrous form and used as low to keep as much inherent water in the fibers as pos filler material. sible. 10 What is claimed is: _ After blending the heated fibrous mixture and the mol 1. In a shotshell cartridge wherein a basewad is posi ten wax binder, the mixture is cooled and moisture added tioned at the rear end thereof, said basewad comprising to bring the moisture content to the original content of an individually molded structure coherent under firing the fibers (4 to 616% wet basis). If the moisture is not conditions and consisting essentially of a mixture of 30 brought up to the original content, the final wad will 15 60% of asbestos fibers and 70-40% of wood fibers held take on moisture from the air and swell. If there is too together by a wax binder means to form a compact mass much moisture in the mixture the final wad will give off of sufficient density and strength to prevent gas leakage the excess moisture and shrinking will result. The mix and rupture upon firing. ture can be cooled at room temperature or by feeding 2. In a shotshell cartridge as described in claim 1 the mixture to a cooler. Also, the moisture content can 20 wherein said wax binder means consists essentially of a be raised or lowered as circumstances require. mixture of microcrystalline wax, paraffin wax, and an ad From the cooler, the mixture goes to a storage hopper ditive added to the wax to add strength and resiliency and then to feeders which feed the cooled-dry mix to thereto. the tableting or compressing machine where the mix is 3. In a shotshell catridge as described in claim 2 where individually apportioned and molded at pressures rang 25 in said additive is butyl rubber and wherein said wax is ing from 10,000 to 40,000 pounds per square inch. present in an amount equal to 5-15% of the weight of It is possible to mold the basewads without cooling said fiber mixture. the blended mixture of fibrous material and wax binder. 4. A cartridge basewad comprising an individually However, the hotter the material, the more difficult it is molded structure coherent under firing conditions and to produce a physically strong basewad which can stand 30 consisting essentially of a mixture of asbestos fibers and the material handling of the wads after they come from at least one other filler material which can be easily and the tableting machine. The strength obtained in cool uniformly coated with a binder, said other filler material ing the mixture prior to tableting aids materially in the selected from the group of low density, fibrous materials handling of the wads after they are ejected from the consisting of ligneous cellulose fibers, plastic flour tableting machine. _ 35 (phenolics) when in fiber form, cellulose acetate fibers, A slightly modified process utilizes the addition of polyvinyl alcohol fibers, and polyvinyl acetate fibers, said calcium resinate to the wax or wax blend in order to asbestos and said other filler material being held together permit the use of higher percentages of wax (and wax by a binder to form a compact mass of sufficient density blends) binders without altering the obturating character and strength to prevent gas leakage and rupture upon istics of the basewad and without sacrificing rigidity and 40 firing, said binder having a melting point between about strength. The modified process is useful to cut down 120 F. to about 200 F. and a needle penetration index on the amount of "dusting" which occurs when basewads of between 5 to 100 tenths of a millimeter (at 77 F. and made according to the original process are used. With 100 gram load according to ASTM Test D1321-5'7T). the higher wax content, greatly improved moisture re 5. A cartridge basewood as recited in claim 4 wherein sistance is obtained as well as increased resistance to 45 said binder comprises a blend of microcrystalline wax, erosion and splitting tendencies of a dry mold basewad. paraffin wax, and calcium resinate. It is believed that the calcium resinate improves the bind 6. A cartridge basewood as recited in claim 5 wherein ing properties of the wax (adhesion and tensile strength) said binder is present in an amount equal to about 15 without inducing brittleness. 20% of the weight of the unblended mixture. Assuming that the fibers to be used in the modified 50 7. A cartridge wad consisting essentially of an individ process are asbestos and wood fibers, the mixture is ually cold-molded mixture of 30-60% of asbestos fibers, blended in a ribbon mixer and heated to a temperature 70-40% of lignous cellulose fibers, and a wax binder of about 120 F.-200 F., although the preferred range present in an amount equal to about 15-20% of the is about 180 F.-200" F. After several minutes mixing weight of the fibers, said wax binder having a melting or at such time that the asbestos and wood fibers have 55 point between 120 F. to 200 F. and a needle penetra been thoroughly mixed, precipitated calcium resinate is tion index of between 5 to 100 tenths of a millimeter (at added and the mixing continued to produce a homoge 77 F., 100 gram load according to ASTM Test D1321- neous blend. The percentage of precipitated calcium res 57T) and including calcium resinate equal to about 4 inate added is determined by the properties desired in 5% of the weight of the blended fibers. the molded basewad. In the present example where the 60 asbestos-wood fiber ratio is about 40-60, the calcium res References Cited by the Examiner inate addition is equal to about 4-5% of the total weight UNITED STATES PATENTS of the asbestos-wood fiber blend. To the above mixture, a molten binder, preferably a blend of microcrystalline wax and paraffin wax is sprayed 05 126,615 128,231 1,771,898 5/1872 W o o d ______________ 102--95 6/1872 L o v e tt_______________ 102--95 7/1930 O'Neil et a l . __________ 102--44 on to the mixture of fibers and calcium resinate. The 2,827,666 3/1958 W agner____________ 264-- 128 percentage of wax blend used depends on the properties 3,141,814 7/1964 S ch u ltz____________ 162-- 155 desired in the molded basewad and in the present ex 3,184,373 5/1965 Arledter ___________ 162-- 155 ample is equal to about 15-20% of the total weight of 3,188,369 6/1965 G u th rie ____________ 264-- 128 the asbestos-wood fiber mixture. After all the ingre 70 dients have been mixed at a temperature of about 180 BENJAMIN A. BORCHELT, Primary Examiner. F.-200 F. and thoroughly blended, the batch is trans- R. F. STAHL, Assistant Examiner.