| 摘要 |
PURPOSE:To obtain superior positively electrostatically chargeable developer without requiring addition of a charge controller by using a binder resin composed essentially of a specified polyester resin, and a copolymer of a hydrophobic monomer and a monomer contg. an amino group, and using a carrier coated with a vinyl chloride type copolymer. CONSTITUTION:A polyester resin is obtained by polymerizing an acid component consisting of bi-valent or higher valent carboxylic acid, its anhydride, or its lower alkyl ester, and an diol component represented by formula I in which R is ethylene or propylene group, x, y are each an integer of >=1, and the average value of the sum of them is 2-7. A copolymer is obtained by polymerizing with an azonitrile type initiator, a mixture of 95.0-99.95wt% hydrophobic copolymerizable monomer and 5.0-0.05wt% copolymerizable monomer having a tertiary amino group represented by formula II in which R1 is H or methyl, R2, R3 are each 1-4C alkyl or aryl, X is ester or amide, and n is an integer of 1-4. A binder resin consists of 10-50pts.wt. of said polyester resin and 50-90pts.wt. of said copolymer resin. A carrier is coated with a vinyl chloride- vinyl acetate copolymer in a weight ratio of (70-98):(2-30). Each of said polyester and said copolymer has a softening point of 100-180 deg.C. As a result, a sharp image free from background stains can be obtained and storage stability of an image stored in a file made of PVC is good. |
