| 摘要 |
<p>PROBLEM TO BE SOLVED: To produce a binder type carrier not causing the problem of image deficiency such as voids with high productivity by melting and kneading a mixture of a resin binder with magnetic powder under specified conditions by means of a specified extruding-kneading machine. SOLUTION: A mixture of a resin binder with magnetic powder is melted and kneaded by means of an extruding-kneading machine with a conveying part 2 and a kneading part 3 in the axial direction in a cylinder 1. When the full length of the conveying part is represented by L, the length of the kneading part in the axial direction by Lnd, the diameter of a screw by D and the length of the conveying part up to the kneading part by L1 , L/D>=23, Lnd/D<=4 and 0.05<=L1 /L<=0.87 are satisfied. The temp. (c) ( deg.C) of the cylinder and the magnetic powder content (a1 ) of the resultant carrier are set so as to satisfy the equation c=7.2(a1 -75)+K1 (where a1 is 75-95wt.% and K1 is the softening point of the resin binder to (the softening point) + 48 deg.C, preferably (the softening point) + 12 deg.C to (the softening point) + 36 deg.C.</p> |
