| 摘要 |
PURPOSE:To ensure superior electrostatic chargeability of positive polarity without using an additive, such as charge controller and to sharpen an image by using a composition consisting of a specified polyester resin, a copolymer of a hydrophobic monomer and a monomer contg. an amino group, and a rubber-like elastomer. 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 composition used for a toner binder resin consists of 19.5- 89.5wt% of said polyester resin, 10-80wt% of said copolymer resin, and 0.5-20wt% of a rubber-like elastomer, such as polybutadiene, especially 1,2-polybutadiene, having a number average mol.wt. of 3,000-200,000, and a m.p. of 50-120 deg.C. Each of said polyester and said copolymer has a softening point of 100-180 deg.C. |
