Provided is a toner containing a toner particle including a binder resin, a wax, and a colorant. The softening point of the toner is at least 80 C. and not more than 140 C. The average circularity of the toner is at least 0.940. The integrated value of stress in the toner at 150 C. which is measured by using a tackiness tester is at least 78 g.Math.m/sec.

The invention provides: an electrostatic image-developing toner external additive including granulated silica which is a granulated material of silica powders each having a primary particle size of 5 to 50 nm and a degree of hydrophobization of 50% or more, the granulated silica having a loose bulk density of 150 g/L or more; and a toner including the electrostatic image-developing toner external additive. These provide an electrostatic image-developing toner external additive excellent in handleability and workability and also capable of improving image quality, and a toner using the external additive.

The invention relates to a hydrophobic silica powder which is unprecedentedly insensitive to environmental humidity with which electrophotographic toner can possess stable electro static charge that leads to stable quality of printed image. The hydrophobic silica powder has the following physicochemical properties; average primary particle size (D) is 30-2000 nm, B*D<430 nm, while B stands for weight % of adsorbed water vapor on silica (100 weight %) when the partial pressure of water to the equilibrium vapor pressure of water at 25 C. is 80% and D stands for average primary particle size (nm) of the silica powder, B/C<2.7, while C stands for weight % of adsorbed water vapor on silica (100 weight %) when the partial pressure of water to the equilibrium vapor pressure of water at 25 C. is 20%, and carbon content>0.30 wt.-%.

An electrostatic latent image developing toner includes a plurality of toner particles (10) each including a toner mother particle (11) and an external additive adhering to a surface of the toner mother particle (11). The toner mother particles (11) contain a crystalline polyester resin and a non-crystalline polyester resin. The toner particles (10) include, as the external additive, crystal nucleating agent particles (13) containing a crystal nucleating agent for promoting crystallization of the crystalline polyester resin. On a differential scanning calorimetry spectrum of the toner before fixing, an endotherm quantity of a heat absorption peak originating from a crystalline region of the crystalline polyester resin is less than 2.0 mJ/mg. On a differential scanning calorimetry spectrum of the toner after fixing, an endotherm quantity of a heat absorption peak originating from a crystalline region of the crystalline polyester resin is at least 6.0 mJ/mg.

To provide a toner for electrophotography exhibiting an excellent charge rise property, and a process for producing the same.

[1] A toner for electrophotography containing a binder resin, and a polyhydroxyamine compound represented by the following formula (1) in an amount of 0.001 part by mass or more and 5.0 parts by mass or less per 100 parts by mass of the binder resin, and [2] a process for producing a toner for electrophotography, including: melt-kneading a toner raw material mixture containing a binder resin, and a polyhydroxyamine compound represented by the following formula (1) in an amount of 0.001 part by mass or more and 5.0 parts by mass or less per 100 parts by mass of the binder resin; and pulverizing a resulting melt-kneaded material.

A toner contains toner particles, titanate fine particles having a Group II element, and hydrotalcite compound fine particles as an external additive and satisfying 10Lt80 and 100LhWeight average particle diameter (D4) of toner particles0.50, when the number average particle diameter (D1) of primary particles of the titanate fine particles is defined as Lt (nm) and the number average particle diameter (D1) of primary particles of the hydrotalcite compound fine particles is defined as Lh (nm).

An electrostatic latent image developing toner includes toner particles having silica particles as an external additive on surfaces of toner base particles, wherein surfaces of a part or all of the silica particles are modified with silicone oil, and the following relational formula (1) is satisfied.

0.30Si(B)/Si(A)0.65relational formula (1)

[In the relational formula (1), Si(A) represents a NET intensity of a Si element contained in the electrostatic latent image developing toner, measured by a wavelength dispersive X-ray fluorescence analyzer. Si(B) represents a NET intensity of a Si element contained in the electrostatic latent image developing toner ultrasonically dispersed in water, measured by a wavelength dispersive X-ray fluorescence analyzer.]

A developing device, includes a first storage chamber that stores developer; a first conveyor that is disposed in the first storage chamber and conveys developer; a developer supporter that is disposed so as to face an image supporter, supports developer conveyed from the first conveyor, and conveys the supported developer to a developing position where an electrostatic latent image formed on the image supporter is developed; a second storage chamber that stores developer conveyed via the developing position and communicates with the first storage chamber at a confluent opening; a second conveyor that is disposed in the second storage chamber and conveys developer conveyed via the developing position toward the confluent opening; and a third storage chamber that stores developer overflowing in a case where an amount of developer in the second storage chamber becomes a predetermined amount or more.

A developing device, includes a first storage chamber that stores developer; a first conveyor that is disposed in the first storage chamber and conveys developer; a developer supporter that is disposed so as to face an image supporter, supports developer conveyed from the first conveyor, and conveys the supported developer to a developing position where an electrostatic latent image formed on the image supporter is developed; a second storage chamber that stores developer conveyed via the developing position and communicates with the first storage chamber at a confluent opening; a second conveyor that is disposed in the second storage chamber and conveys developer conveyed via the developing position toward the confluent opening; and a third storage chamber that stores developer overflowing in a case where an amount of developer in the second storage chamber becomes a predetermined amount or more.

It is an object to suppress yellowing of a binder resin while obtaining an image with a high degree of whiteness and to suppress occurrence of image defects when printing at a high temperature and a high humidity. A toner for developing an electrostatic image, the toner including: white toner base particles containing a binder resin and titanium oxide having an average particle size of from 130 to 600 nm; and an external additive including strontium titanate.