Pressure-fixing toner for electrophotography and process for preparation thereof

Claim 2

A pressure-fixable toner suitable for use in electrophotography, which toner comprises electroscopic particles of irregular shape and comprising, as a pressure-fixing binder component, a composite binder component comprising (A) a wax component and (B) a resin component composed mainly of styrene-acrylic copolymer at an (A): (B) weight ratio of from 54:46 to 20:80, the wax component (A) being present in the form of spherical particles having an average particle size of smaller than 10 pm in a continuous phase of the resin component (B).

Claim 3

A toner according to claim 1, wherein the wax component (A) is an olefin polymer wax having a molecular weight of 500 to 10,000.

Claim 4

A toner according to claim 1 or 2, wherein the molecular weight of the styrene-acrylic copolymer is from 3,000 to 300,000.

Claim 5

A toner according to any one of the preceding claims, wherein, in the styrene-acrylic copolymer, the styrene-type monomer is present in an amount from 90 to 30% by weight and the acrylic monomer is present in an amount of from 10 to 70% by weight.

Claim 6

A toner according to any one of the preceding claims, which further comprises a pigment in an amount of 1 to 500% by weight based on the composite binder.

Claim 7

A toner according to any one of the preceding claims, wherein the electroscopic particles of irregular shape have an average particle size of from 1 to 50 microns.

Claim 8

A process for the preparation of a pressure-fixable toner suitable for use in electrophotography, which process comprises cooling a solution obtained by hot-dissolving a wax component (A) in an aromatic solvent to precipitate spherical particles of the wax component (A) having an average particle size of smaller than 10 microns and copolymerizing a styrene-type monomer with an acrylic monomer in the system containing the spherical particles of the wax component (A) to form a composite binder comprising the wax component (A) and the resin component (B) composed mainly of the resulting styrene-acrylic copolymer at an (A):(B) weight ratio of from 54:46 to 20:80, the wax component (A) being present in the form of spherical particles having an average particle size of smaller than 10 microns in a continuous phase of he resin component (B),'kneading the composite binder, and cooling and pulverizing the kneaded composite binder to form particles of irregular shape.

Claim 9

A process for the preparation of a pressure-fixable toner suitable for use in electrophotography, which process comprises cooling a solution obtained by hot-dissolving a wax component (A) in an aromatic solvent to precipitate spherical particles of the wax component (A) having an average particle size of smaller than 10 microns and copolymerizing a styrene-type monomer with an acrylic monomer in the system containing the spherical particles of the wax component (A) to form a composite binder comprising the wax component (A) and the resin component (B) composed mainly of the resulting styrene-acrylic copolymer at an (A):(B) weight ratio of from 54:46 to 20:80, the wax component (A) being present in the form of spherical particles having an average particle size of smaller than 10 microns in a continuous phase of he resin component (B),'kneading the composite binder, and cooling and pulverizing the kneaded composite binder to form particles of irregular shape.

Claim 10

A process for the preparation of a pressure-fixable toner suitable for use in electrophotography, which process comprises cooling a solution obtained by hot-dissolving a wax component (A) in an aromatic solvent to precipitate spherical particles of the wax component (A) having an average particle size of smaller than 10 microns, uniformly mixing and dispersing the resulting emulsion of the wax component (A) with a solution of a styrene-acrylic copolymer and removing the solvent under such conditions that re-dissolution or growth of the particles of the wax component (A) is not caused, to form a composite binder comprising the wax component (A) and a resin component (B) composed mainly of the styrene-acrylic polymer at an (A):(B) weight ratio of from 54:46 to 20:80, the wax component (A) being present in the form of spherical particles having an average particle size of smaller than 10 microns in a continuous phase of the resin component (B), kneading the composite binder, and cooling and pulverizing the kneaded composite binder to form particles of irregular shape.

Claim 11

A process for the preparation of a pressure-fixable toner suitable for use in electrophotography, which process comprises cooling a solution obtained by hot-dissolving a wax component (A) in an aromatic solvent to precipitate spherical particles of the wax component (A) having an average particle size of smaller than 10 microns, uniformly mixing and dispersing the resulting emulsion of the wax component (A) with a solution of a styrene-acrylic copolymer and removing the solvent under such conditions that re-dissolution or growth of the particles of the wax component (A) is not caused, to form a composite binder comprising the wax component (A) and a resin component (B) composed mainly of the styrene-acrylic polymer at an (A):(B) weight ratio of from 54:46 to 20:80, the wax component (A) being present in the form of spherical particles having an average particle size of smaller than 10 microns in a continuous phase of the resin component (B), kneading the composite binder, and cooling and pulverizing the kneaded composite binder to form particles of irregular shape.

Claim 12

A process according to claim 7 or 8, wherein the composite binder is kneaded together with a pigment.

Claim 13

Use of pressure-fixable toner as claimed in any one of claims 1 to 6 or which has been produced by a process as claimed in any one of claims 7 to 9, in electrophotography in the development of electrostatic latent images.