| 摘要 |
PURPOSE: To obtain a magnetic ink which makes it possible to prevent the forgery of printed matter and distinguish the true from the false by dispersing a magnetic powder serving as a light-colored pigment and comprising bismuth/ rare earth element/iron garnet crystal particles ground to a specified particle diameter in a binder resin. CONSTITUTION: A solvent is added to a mixture of a magnetic powder serving as a light-colored pigment and comprising bismuth/rare earth element/iron garnet crystal particles of the formula (wherein 1.8<=x<=3.0; 0<=y<=5; R is Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu; Bi is an element that substitutes for R; Fe is an element that substitutes for M; M is Al, Ga, Cr, Mn, Sc, In, Ru, Rh, Co, Cu, Ni, etc.; and R, Bi and Fe, M and O respectively occupy the c, a and/or d, h sites in the garnet crystal structure) ground to 10-50nm and a binder resin at a weight ratio of (1 to 5):1 to form a dispersion, thus giving a magnetic ink. The use of this ink for the ground tint 2 in the number area of a lottery ticket 1 can prevent an illegality. |
