GB1050711A - - Google Patents

Abstract

1,050,711. Melt-spinning. COLUMBIA RIBBON CARBON MANUFACTURING CO. Inc. Aug. 4, 1964 [Oct. 4, 1963], No. 30900/64. Heading B5B. [Also in Divisions B6 and D1] A pressure-sensitive ink-ribbon woven from synthetic plastic filaments is characterized in that the filaments are porous and have within the pores a liquid, pressure-exudable ink composition. The filaments used for weaving or matting of the ink ribbon are extruded from synthetic plastic materials including polyolefins such as polyethylene or polypropylene; vinyl resins such as polystyrene, polyvinyl chloride, polyvinyl acetate or copolymers thereof or polyvinylidene chloride; polyamides such as nylon; polyethylene terephthalate polyester, polyacrylonitrile and cellulosic plastics such as rayon acetates. Prior to extrusion the synthetic plastic material is uniformly compounded with an amount of a pore-forming agent which may be a liquid or a gas, but in the preferred embodiment a finally particulate solid is used. The pore-forming agents may be gaseous materials such as freon, nitrogen, ammonia or carbon dioxide; volatile liquids, which are non-solvents for the particular plastics material used such as water, toluene, ethanol or ammonium hydroxide; or solid materials, which decompose at the elevated temperatures of the process to liberate gaseous or volatile liquid material and viz. benzenesulphonyl hydrazide, dinitroso therephthalamide, diazo-aninobenzine, diniprosopentamethylenitetramine, which decompose at temperatures above 90‹ C. to evolve such gases as nitrogen oxide, carbon dioxide or water vapour. The preferred amount ranges between 1 to about 5 parts by weight of the extrusion composition. The extrusion composition is then agitated to obtain a uniform dispersion and introduced into an extrusion machine where the temperature is maintained between 125‹ to 300‹ C. to melt the synthetic plastic and to vaporize or decompose the agent to form the gases, which are dispersed throughout the composition by pressures varying between slightly above atmospheric to a pressure of 40 to 50 atmospheres. As soon as the composition is extruded into the atmosphere, the gases are liberated to form a porous network within said filaments. The filaments are then passed through a liquid coolant such as water or a salt solution and may thereafter be woven or matted into a fabric and subsequently impregnated with oil and colouring matter. Following extrusion the filaments, if desired, may be stretched by passing them over rollers, contacting them with steam to stretch the filaments to the required thickness. In the preferred embodiment the filaments are reduced to a denier ranging between 0À05 and 4. Prior to weaving, the extruded filaments may be twisted together in groups of 10 to 40 to form multi-filament strands. The filaments may also be woven together using an admixture of conventional filaments.