Toner for developing electrostatic image and process for production thereof

A process for producing a toner, comprising the steps of:

• (i) melt-kneading a mixture including a binder resin, a colorant, and a release agent in amounts from 1-40 wt. parts per 100 wt. parts of the binder resin, said release agent comprising an ester compound having 1 to 4 ester groups selected from the group consisting of ester compounds (a), (b) and (c) shown below:
• (a) a poly-functional ester having a tertiary carbon or/and a quaternary carbon and obtained from an alcohol compound or carboxylic compound having at least two functional groups,
• (b) a mono-functional ester having a tertiary carbon or/and a quaternary carbon, and
• (c) a poly-functional ester having a primary or secondary carbon having at least two functional groups represented by the following formula (1):
• ##STR21## wherein A denotes a carbon atom or alicyclic group, R.sub.1 and R.sub.2 independently denote an organic group having 1-35 carbon atoms, Y.sub.1 and Y.sub.2 independently denote a hydrogen atom, halogen atom or organic group, m and n denote 0 or an integer of at least 1, X.sub.1 and X.sub.2 independently denote an oxygen atom or sulfur atom, and Z.sub.1 and Z.sub.2 independently denote an oxygen atom or sulfur atom, with the proviso that
• at least one of Y.sub.1 and Y.sub.2 denotes an organic group when A denotes a carbon atom and m and n are 0,
• at least one of Y.sub.1 and Y.sub.2 denotes a hydrogen atom or halogen atom when A denotes a carbon atom and either one of m and n denotes an integer of at least 1, and
• Y.sub.1 and Y.sub.2 denote a hydrogen atom or halogen atom with the proviso that at least one of Y.sub.1 and Y.sub.2 is a halogen atom when A denotes a carbon atom and m and n are an integer of at least 1, thereby to form a melt-kneaded product,
• (ii) cooling the melt-kneaded product,
• (iii) pulverizing the cooled melt-kneaded product to obtain a pulverized product, and
• (iv) classifying the pulverized product to obtain toner particles.

A process for producing a toner, comprising the steps of:

• (i) forming into particles a mixture including a polymerizable monomer, a colorant, and a release agent in amounts from 1-40 wt. parts per 100 wt. parts of the binder resin, said release agent comprising an ester compound having 1 to 4 ester groups selected from the group consisting of ester compounds (a), (b) and (c) shown below:
• (a) a poly-functional ester having a tertiary carbon or/and a quaternary carbon and obtained from an alcohol compound or carboxylic compound having at least two functional groups,
• (b) a mono-functional ester having a tertiary carbon or/and a quaternary carbon, and
• (c) a poly-functional ester having a primary or secondary carbon having at least two functional groups represented by the following formula (1):
• ##STR22## wherein A denotes a carbon atom or alicyclic group, R.sub.1 and R.sub.2 independently denote an organic group having 1-35 carbon atoms, Y.sub.1 and Y.sub.2 independently denote a hydrogen atom, halogen atom or organic group, m and n denote 0 or an integer of at least 1, X.sub.1 and X.sub.2 independently denote an oxygen atom or sulfur atom, and Z.sub.1 and Z.sub.2 independently denote an oxygen atom or sulfur atom, with the proviso that
• at least one of Y.sub.1 and Y.sub.2 denotes an organic group when A denotes a carbon atom and m and n are 0,
• at least one of Y.sub.1 and Y.sub.2 denotes a hydrogen atom or halogen atom when A denotes a carbon atom and either one of m and n denotes an integer of at least 1, and
• Y.sub.1 and Y.sub.2 denote a hydrogen atom or halogen atom with the proviso that at least one of Y.sub.1 and Y.sub.2 is a halogen atom when A denotes a carbon atom and m and n are an integer of at least 1;
• and
• (ii) polymerizing the particles of the mixture to obtain toner particles.