GB147522A - Improved casing for "sticks" of fragile and soft materials for drawing, writing and the like purposes - Google Patents

Abstract

147,522. Soc. Anon. des Anciens Etablissements J. M. Paillard. May 25, 1919, [Convention date]. Pencils and crayons.-Sticks or " leads " of plumbago, chalk, pastels, &c. are enclosed in a casing formed from a plastic mass composed of vegetable organic materials, inert mineral substances, and agglomerating-materials, which is applied directly upon the sticks or " leads " by means of an apparatus of known form comprising a die fed under pressure. The plastic material consists preferably of 30 parts of vegetable materials, such as wood, cork, or rags, finely divided or pulverized, 6 parts of mineral materials, such as talc, clay, lime, gypsum, &c., and 10 parts of agglomerating-materials, such as casein, potassium or sodium silicates, glues, resins, or gums. The material is mixed and kneaded with about an equal weight of water, and may have any desired pigment or dye incorporated with it. The die consists of two concentric tubes 1, 2, Fig. 1, the inner one receiving the leads y, which are placed end to end, and the outer one receiving the pasty material through a pipe 3 under mechanical, hydraulic, or air pressure. The tube 2 is contracted opposite to the end of the tube 1, and its continuation is formed of circular, elliptical, or polygonal section according to the desired form of the casing. The sticks are drawn through the die by the pressure of the plastic material, the successively encased sticks breaking away and being dried by suitable means. The encasing may be effected in successive layers which are separately dried, and the outer layers mav be harder than the inner layers and differently coloured. The material may be fed by a rotary screw 7, Fig. 6, enclosed in a casing 10 having a feed-hopper 13.