Toner producing method using recycled extra-fine toner particles

A toner producing method in which the normal process is carried out by the steps of:

• mixing starting materials comprising a binder resin, a coloring agent, and a charge control agent;
• fusing and kneading the mixture to provide a kneaded compound;
• cooling the kneaded compound;
• crushing the cooled compound into particles;
• and classifying the particles into toner particles having a desired particle size diameter and extra-fine powder toner equal to or below a prescribed size,
• said method comprising the steps of:
• recycling the extra-fine powder toner by mixing it with the starting materials to provide a mixture;
• fusing and kneading the mixture to provide a kneaded compound;
• cooling the kneaded compound;
• crushing the compound into toner particles;
• and
• classifying the particles to remove extra-fine toner particles,
• being characterized in that when the extra-fine powder toner is blended with the starting materials, the blending ratio of the extra-fine powder toner to the starting material is set between 5 wt. % and 10 wt. %, and the blending ratios of the charge control agent and the coloring agent are set equal to those of the normal process.

A toner producing method in which the normal process is carried out by the steps of:

• mixing starting materials comprising a binder resin, a coloring agent, and a charge control agent;
• fusing and kneading the mixture to provide a kneaded compound;
• cooling the kneaded compound;
• crushing the cooled compound into particles;
• and classifying the particles into toner particles having a desired particle size diameter and extra-fine powder toner equal to or below a prescribed size,
• said method comprising the steps of:
• recycling the extra-fine powder toner by mixing it with the starting materials to provide a mixture;
• fusing and kneading the mixture to provide a kneaded compound;
• cooling the kneaded compound;
• crushing the compound into toner particles;
• and
• classifying the particles to remove extra-fine toner particles,
• being characterized in that when the extra-fine powder toner is blended with the starting materials, the blending ratio of the extra-fine powder toner to the starting material is set between 10 wt. % and 20 wt. %, and the blending ratio of the coloring agent is set equal to that of the coloring agent in the normal process while the blending ratio of the charge control agent is set between 1.5 and 2 times that of the normal process.

A toner producing method in which the normal process is carried out by the steps of:

• mixing starting materials comprising a binder resin, a coloring agent, and a charge control agent;
• fusing and kneading the mixture to provide a kneaded compound;
• cooling the kneaded compound;
• crushing the cooled compound into particles;
• and classifying the particles into toner particles having a desired particle size diameter and extra-fine powder toner equal to or below a prescribed size,
• said method comprising the steps of:
• recycling the extra-fine powder toner by mixing it with the starting materials to provide a mixture;
• fusing and kneading the mixture to provide a kneaded compound;
• cooling the kneaded compound;
• crushing the compound into toner particles;
• and
• classifying the particles to remove extra-fine toner particles,
• being characterized in that when the extra-fine powder toner is blended with the starting materials, the blending ratio of the extra-fine powder toner to the starting material is set between 10 wt. % and 20 wt. %, and the blending ratio of the charge control agent is set equal to that of the charge control agent in the normal process while the blending ratio of the coloring agent is set between 0.66 and 0.83 times that of the normal process.

A toner producing method in which the normal process is carried out by the steps of:

• mixing starting materials comprising a binder resin, a coloring agent, and a charge control agent;
• fusing and kneading the mixture to provide a kneaded compound;
• cooling the kneaded compound;
• crushing the cooled compound into particles;
• and classifying the particles into toner particles having a desired particle size diameter and extra-fine powder toner equal to or below a prescribed size,
• said method comprising the steps of:
• recycling the extra-fine powder toner by mixing it with the starting materials to provide a mixture;
• fusing and kneading the mixture to provide a kneaded compound;
• cooling the kneaded compound;
• crushing the compound into toner particles;
• and
• classifying the particles to remove extra-fine toner particles,
• being characterized in that when the extra-fine powder toner is blended with the starting materials, the blending ratio of the extra-fine powder toner to the starting material is set between 10 wt. % and 15 wt. %, and the blending ratio of the charge control agent is set between 1.6 and 1.8 times that in the normal process while the blending ratio of the coloring agent is set between 0.7 and 0.75 times that of the normal process.

A toner producing method for producing toner particles having a prescribed particle size, said method comprising the steps of:

• mixing a coloring agent and a binder resin as main components to provide a mixture;
• heating and kneading the mixture to provide a kneaded compound;
• cooling the kneaded compound;
• crushing the cooled compound into toner particles;
• classifying the particles to remove extra-fine toner particles;
• and
• returning the extra-fine toner particles smaller than the prescribed size to the mixing step for recycling;
• wherein the binder resin has a particle size, which is set so that the tractive ability of the compound entering the kneading shaft during kneading is equivalent to that of the case where no extra-fine toner is added, and this binder resin is blended with the extra-fine toner so as to eject a constant amount of the kneaded compound,
• wherein the binder resin is composed of particles having a particle size diameter a (mm) which satisfies the following condition:
• 3.0.ltoreq.a.ltoreq.k.times.(1/b).times.c.sup.2
• where b is the mean particle diameter (.mu.m) of the extra-fine toner, c is the blending ratio (wt. %) of the extra-fine toner, and k is equal to 1.8.times.10.sup.-2.