MANUFACTURE OF MAGNETICALLY ENCODABLE CARD WITH UNIFORMLY DISPERSED MAGNETIC PARTICLES AS WHOLE

摘要

PROBLEM TO BE SOLVED: To obtain a magnetically encodable card by preparing a dispersion solution having ferromagnetic particles dispersed into an organic fluid medium, and closely mixing the dispersion solution with thermoplastic resin plasticized with the organic fluid medium to prepare a composite material. SOLUTION: Ferromagnetic particles such asγ-Fe2 O3 are dispersed into an organic fluid medium such as phosphoric ester to prepare a dispersion solution, and then the dispersion solution is mixed with thermoplastic resin such as polystyrene to prepare a composite material. During preparation of this composite material, a dispersing agent such as a product of phosphoric ester is included therein, but another of various types of dispersing agents may be used. In order to obtain a white color reflecting surface suitable for accommodation of image, etc., for example, particles ofα-alumina are added to pigment containing metal oxide or oxide mixture or metallic carbonate, e.g. zinc oxide for providing an anti-friction characteristic to thereby form a composite material. The composite material is formed into a magnetically encodable card. Since the magnetic particles are entirely uniformly dispersed, a magnetic signal in the card will not reduced even after the card is used many times.