# US 8,785,093 B2 · Image forming toner, and developer and process cartridge using the toner

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- Number: US 8,785,093 B2
- Document ID: US8785093B2
- Status: Granted
- Kind: B2
- Application number: 12/260,493
- Filed: 2008-10-29
- Published: 2009-06-04
- Granted: 2014-07-22
- Earliest claimed: 2007-11-30
- Assignees: Ricoh Company, Ltd.
- Applicants: Toyoshi Sawada; Tomomi Suzuki; Tsuneyasu Nagatomo; Satoshi Kojima
- Inventors: Toyoshi Sawada; Tomomi Suzuki; Tsuneyasu Nagatomo; Satoshi Kojima
- Web page: https://patentgrep.com/patent/US8785093B2

## CPC

- G03G 21/1814: {Details of parts of process cartridge, e.g. for charging, transfer, cleaning, developing (G03G21/1835 takes precedence)}
- G03G 9/0806: {whereby chemical synthesis of at least one of the toner components takes place}
- G03G 9/08755: {Polyesters}
- G03G 9/08782: {Waxes}
- G03G 9/08793: {Crosslinked polymers}
- G03G 9/08795: {characterised by their chemical properties, e.g. acidity, molecular weight, sensitivity to reactants}
- G03G 9/08797: {characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature}
- G03G 2215/0607: two-component
- G03G 2215/0614: one-component
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

An image forming toner, including a mother particle including a paraffin wax having a melting point of from 60 to 90° C. and a binder resin, wherein the mother particle has an endothermic peak of the paraffin wax of from 2.0 J/g to 5.5 J/g when measured by a DSC and an aspect ratio of from 0.8 to 0.90.

## Claims

### Claim 1

A developer, comprising:
(A) an image forming toner comprising:
(i) a mother particle, comprising:
(1-a) a paraffin wax having a melting point of from 60 to 90° C.; and
(1-b) a binder resin comprising a polyester resin,
wherein the mother particle has an endothermic peak of the paraffin wax of from 2.0 J/g to 5.5 J/g when measured by a DSC and an aspect ratio of from 0.8 to 0.90, and
wherein the mother particle has a shape factor SF-1 of from 130 to 160 and SF-2 of from 110 to 140; and
(B) a carrier coated with at least one of an acrylic resin a silicone resin.

### Claim 2 (depends on 1)

The developer of claim 1, wherein the carrier contains particulate alumina.

### Claim 3 (depends on 1)

The developer of claim 1, wherein the mother particle is prepared by a method comprising:
(1) dispersing at least a polyester prepolymer comprising a functional group comprising a nitrogen atom, a polyester resin, a colorant, the paraffin wax, and an inorganic filler in an organic solvent, to prepare a dispersion; and
(2) dispersing the dispersion in an aqueous medium to subject the polyester prepolymer to at least a crosslinking or an elongation reaction.

### Claim 4 (depends on 3)

The developer of claim 3, wherein the inorganic filler is montmorillonite or modified montmorillonite.

### Claim 5 (depends on 1)

The developer of claim 1, wherein the mother particle has a weight-average particle diameter of from 3 to 8 μm, and a ratio of the weight-average particle diameter to a number-average particle diameter of from 1.00 to 1.30.

### Claim 6 (depends on 1)

The developer of claim 1, wherein the mother particle has a glass transition temperature of from 40 to 60° C.

### Claim 7 (depends on 1)

The developer of claim 1, wherein the mother particle includes particles having a particle diameter not greater than 2 μm in an amount of from 1 to 10% by number.

### Claim 8 (depends on 1)

The developer of claim 1, wherein the mother particle has an average circularity of from 0.950 to 0.980.

### Claim 9 (depends on 1)

A process cartridge, comprising:
a photoreceptor;
the developer of claim 1; and
at least one of a charger and a cleaner, and
wherein the process cartridge is detachable from an image forming apparatus.