What is claimed is:
1. An electrostatic latent image developing agent comprising a toner and a carrier, wherein:
the surface of the toner is covered with one or more kinds of particles;
at least one kind of the one or more kinds of particles has a volume resistivity of 11014 cm or greater and an average primary particle diameter of 50 nm or less;
a total covering ratio of said at least one kind of particles is higher than a total covering ratio of other kinds of particles on the surface of the toner;
a shape factor SF1 of the toner is in the range of from 100 to 140;
the carrier is a resin coated carrier; and
at least a coating resin layer of the resin coated carrier comprises a positively charging resin and a quaternary ammonium salt compound.
2. An electrostatic latent image developing agent according to claim 1, wherein a volume resistivity of the carrier is in the range of from 1109 cm to 11013 cm.
3. An electrostatic latent image developing agent according to claim 1, wherein a core material component exposure ratio of the carrier is 20% or less.
4. An electrostatic latent image developing agent according to claim 1, wherein the toner is manufactured by a wet method.
5. An electrostatic latent image developing agent according to claim 1, wherein the particles comprise silicone-treated silica.
6. An electrostatic latent image developing agent according to claim 1, wherein a content of the quaternary ammonium salt compound is in the range of from 1 to 60 parts by mass per 100 parts by mass of the positively charging resin.
7. An electrostatic latent image developing agent according to claim 1, wherein an amount of the positively charging resin is in the range of from 0.05 to 5.0% by mass with respect to a total mass of the carrier.
8. An electrostatic latent image developing agent according to claim 1, wherein an average film thickness of the positively charging resin is in the range of from 0.1 to 10 m.
9. An electrostatic latent image developing agent according to claim 1, wherein a volume resistivity of the carrier is in the range of from 109 to 1013 cm at a development contrast potential in the range of from 103 to 104 Vcm.
10. An electrostatic latent image developing agent according to claim 1, wherein an amount of the particles is in the range of from 0.3 to 5 parts by mass per 100 parts by mass of the toner.
11. An electrostatic latent image developing agent according to claim 1, wherein a volume average particle diameter of the toner is in the range of from 2 to 12 m.
12. An electrostatic latent image developing agent according to claim 1, wherein a ratio of a volume average particle diameter of the carrier to a volume average particle diameter of the toner is in the range of from 2:1 to 15:1.
13. An image forming method comprising at least a charging step of charging a surface of an electrostatic latent image bearing member; an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image bearing member; a developing step of transforming the electrostatic latent image into a toner image by using an electrostatic latent image developing agent; a transfer step of transferring the toner image formed on the surface of the electrostatic latent image bearing member onto a surface of a receiving substrate; a fixing step of thermally fixing the toner image transferred onto the surface of the receiving substrate; and a cleaning step of removing the toner remaining on the surface of the electrostatic latent image bearing member,
wherein:
the electrostatic latent image developing agent comprises a toner and a carrier;
the surface of the toner is covered with one or more kinds of particles;
at least one kind of the one or more kinds of particles has a volume resistivity of 11014 cm or greater and an average primary particle diameter of 50 nm or less;
a total covering ratio of said at least one kind of particles is higher than a total covering ratio of other kinds of particles on the surface of the toner;
a shape factor SF1 of the toner is in the range of from 100 to 140;
the carrier is a resin coated carrier; and
at least a coating resin layer of the resin coated carrier comprises a positively charging resin and a quaternary ammonium salt compound.
14. An image forming method according to claim 13, wherein a volume resistivity of the carrier is in the range of from 1109 cm to 11013 cM.
15. An image forming method according to claim 13, wherein a core material component exposure ratio of the carrier is 20% or less.
16. An image forming method according to claim 13, wherein the toner is manufactured by a wet method.
17. An image forming method according to claim 13, wherein the particles comprise silicone-treated silica.
18. An image forming method according to claim 13, wherein a content of the quaternary ammonium salt compound is in the range of from 1 to 60 parts by mass per 100 parts by mass of the positively charging resin.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A process for preparing spherical polyamide particles having a mean diameter of less than 1mm, comprising the following steps:
a) preparing a dispersion of a first liquid which comprises a solution of polyamide monomers in a solvent, in a second inert liquid thereby forming a reaction medium, the reaction medium comprising two phases, a continuous phase formed by the second liquid, and a dispersed phase formed by the first liquid, the first and second liquids are essentially immiscible, wherein the ratio between the volume of the first liquid and the volume of the second liquid is greater than or equal to 0.5;
b) polymerizing the monomers by polycondensation andor polyaddition by heating the reaction medium and maintaining the heating at a temperature below the melting point of the polyamide with the desired degree of polymerization;
c) optionally, decompressing the reaction medium to atmospheric pressure;
d) optionally, gradually cooling the reaction medium; and
e) recovering the spherical polyamide particles therefrom.
2. The process as defined by claim 1, said first liquid comprising a solution of monomers in water.
3. The process as defined by claim 1, said monomers comprising caprolactam, adipic acid or hexamethylenediamine.
4. The process as defined by claim 1, said second liquid having a boiling point greater than 150\xb0 C. at atmospheric pressure.
5. The process as defined by claim 1, said second liquid comprising an aliphatic hydrocarbon or a mixture of aliphatic hydrocarbons.
6. The process as defined by claim 1, wherein the pressure during step b) ranges from 1 to 20 bar.
7. The process as defined by claim 1, wherein the temperature during step b) is greater than or equal to 150\xb0 C.
8. The process as defined by claim 1, wherein an azeotrope of the second liquid, of the solvent for the monomers of the first liquid and of the by-product of polycondensation is distilled during step b).
9. The process as defined by claim 1, wherein the duration of step b) ranges from 10 to 60 minutes.
10. The process as defined by claim 1, wherein the temperature during step c) is less than the melting point of the polyamide with the desired degree of polymerization.
11. The process as defined by claim 1, comprising a step f) for washing the spherical polyamide particles.
12. The process as defined by claim 1, comprising a step g) for drying the spherical polyamide particles.
13. The process as defined by claim 12, wherein the steps a) to g) are successive.
14. The process as defined by claim 1, wherein the spherical particles have a mean diameter of less than 100 \u03bcm.
15. The process as defined by claim 14, wherein the spherical particles have a mean diameter of less than or equal to 30 \u03bcm.
16. The process as defined by claim 1, said ratio being greater than or equal to 0.75.
17. The process as defined by claim 15, wherein the spherical particles have a mean diameter of less than or equal to 10 \u03bcm.
18. The process as defined by claim 15, wherein the spherical particles have a mean diameter of less than or equal to 5 \u03bcm.
19. The spherical particles of the process as defined by claim 1.
20. The process of claim 1, wherein the reaction medium is free of a dispersion-stabilizing agent or an emulsifying agent.