JP2560706B2 - Dry toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a dry toner for the present electrostatic charge used for development in electrophotography, electrostatic recording and the like.

[Conventional technology]

In the electrophotographic method, an electrostatic latent image formed on a photoconductor is usually developed with resin powder containing a pigment, the obtained visible image is transferred onto a transfer paper, and fixed by heat, pressure, and the combination thereof. In recent years, it has been required to perform this fixing process from high speed to high efficiency.

To this end, in the case of the pressure fixing toner, a substance that easily causes plastic deformation is used for the binder, and in the case of the heat fixing toner, in order to perform high-speed fixing with low power consumption, the toner of the toner is used. An effective means is to lower the softening point of the binder material and lower the melt viscosity.

In the binder polymer (binder resin) that is usually used as the main binder material of the toner, if the softening point is lowered, the fluidity tends to decrease due to caking during toner storage, and if the melt viscosity is lowered, the offset phenomenon may occur. Image stains are more likely to occur.

For this reason, a device for supplying a releasing agent such as silicone oil to the hot roll is provided to prevent offset, increase the glass transition point of the main binder polymer, or use silica or other inorganic ultrafine powder on the toner surface. A method of preventing caking during storage by using it as an external additive has been conventionally proposed.

[Problems to be Solved by the Invention] However, in order to supply silicone oil to the heat roll,
Since a supply mechanism is required, the cost of the device must be reduced, and maintenance for oil supply is also required.

Further, if the glass transition point of the main binder polymer is set high, the softening temperature becomes high, so that low temperature fixing tends to be difficult.

Further, also in the case of the pressure fixing toner, when a material that easily causes plastic deformation is used, fluidity is deteriorated and caking is likely to occur, and filming of the toner material onto the photoconductor is likely to occur. The image is likely to deteriorate, and the image tends to deteriorate over time.

Therefore, it is an object of the present invention to provide a dry toner capable of efficiently fixing at a high speed.

Another object of the present invention is to provide a dry toner which is less likely to cause caking during storage.

Another object of the present invention is to provide a dry toner having high fluidity and capable of forming a uniform image.

Another object of the present invention is to provide a dry toner which hardly causes photoconductor filming.

Another object of the present invention is to provide a dry toner having a good cleaning property.

Furthermore, another object of the present invention is to provide a dry toner capable of providing a stable image for a long period of time.

[Means for solving problems]

In order to solve the above problems, a multi-layer structure toner represented by a microcapsule type has been conventionally proposed. In this case, it is common to use a component that is easily melted by heat as an internal material, a material having a high melting point as a material for the outermost layer, and a material having good fluidity and anti-caking properties as a toner. Usually, waxes or resins having a low glass transition point (Tg) or a low molecular weight are used as a binder as the inner material, and the outermost layer material has a high Tg, a high molecular weight, or a crosslinked structure. Binder is used.

However, unless the pressure responsiveness and the heat deformability of the outermost layer material are strictly optimized, the fixing energy often becomes high, and the fixing-caking resistance functional separation is not necessarily performed.

In addition, a means for improving the fluidity and the resistance to caking resistance by adding inorganic fine powder such as silica, alumina, and titania has been put into practical use. Although it is coated in a substantially capsule shape, it is not completely adhered, and the instability of the adhered state easily causes deterioration of the image with time and deterioration of anti-caking property.

As a result of intensive studies, the present inventors have succeeded in directly depositing and adhering an inorganic compound to the outermost layer of the toner by utilizing a precipitation forming reaction, and completed the present invention.
That is, the present invention is a dry toner in which an inorganic compound is deposited on the surface of the toner by a precipitation forming reaction.

In the dry toner of the present invention, since the inorganic compound is deposited and adhered to the outermost layer of the toner, it has excellent stability over time, and since an inorganic material that is generally difficult to plastically deform can be used, the anti-caking property even in a thin layer state, It is possible to obtain an extremely excellent effect on fluidity.

In order to deposit an inorganic substance in the dry toner of the present invention, a reaction of forming a solid from a solution can be widely used.

That is, for example, in an inorganic chemical reaction in an aqueous solution represented by the following reaction formula A + B → C + D, a core toner is dispersed in an aqueous solution of a compound of A or B, and then this is mixed with an organic solvent. After emulsification to form a water-in-oil emulsion, the mixture is mixed with the other aqueous solution to cause a precipitation-forming reaction on the surface of the aqueous solution droplet in the emulsion, and an inorganic compound wall is formed on the toner surface.

Compounds A and B are water-soluble inorganic salts, inorganic acids, inorganic bases, etc., and organic solvents having low solubility in water are used.

When stirring and / or centrifugal sedimentation is carried out during the reaction, an oil layer and an aqueous layer are separated, so that the toner having a multi-layer structure may be separated from the aqueous layer and dried by a usual spray dryer method.

During the reaction, a surfactant may be used in combination to improve the stability of emulsion.

Specific examples of the reaction that can be used to form the wall of the inorganic compound in the outermost layer of the toner include General precipitation-forming reaction such as.

Also, adding an alkaline solution to ferrous and ferric salts,
Although the precipitation reaction of iron hydroxide or iron hydrate obtained by oxidation can be used, it is not necessarily limited to these, and most precipitation reaction of inorganic compounds can be used.

The reaction mode is generally the precipitation formation reaction by the emulsion described above. However, the component A is attached to the toner surface using a fluidized bed and the like, and then the component B is added to carry out the precipitation formation reaction in the gas phase. Is also possible.

Further, as the core particles, all usual toner compositions are used.

The toner as a core may be produced by any method such as a kneading and pulverizing method, a suspension polymerization method, a spray drying method, and a melt dispersion method.

Further, a conventionally used inorganic compound may be added to and dispersed in a multilayer structure toner in which an inorganic substance is deposited on the surface.

〔Example〕

First, 70 parts by weight of amide wax (melting point 65 ° C.) containing ricinoleic acid amide as a main component, 15 parts by weight of polyethylene wax, and 15 parts by weight of carbon black were kneaded and pulverized to obtain a nuclear toner having an average particle size of 10 μm. Is designated as Toner A.).

This was dispersed in a 1 mol / calcium carbonate aqueous solution in the presence of a surfactant, then dispersed in a benzene solution also containing a surfactant, and agitated with a disperser to temporarily generate emulsion. This emulsion was mixed with 0.2 mol / calcium chloride aqueous solution with vigorous stirring, and stirring was continued for 20 minutes.

After that, it is subjected to a centrifugal separator to separate it into an oil layer and an aqueous layer, the toner is separated from the aqueous layer, washed with water, and then dried by a spray drying method, whereby a toner having much better fluidity than Toner A is obtained. (This is designated as Toner B).

Toner A (untreated) and Toner B (calcium carbonate capsule toner) were respectively subjected to a caking test at 50 ° C. for 24 hours. As a result, Toner A showed a lot of aggregation, and Toner B was almost the same as before the test. It was

When A and B toners were mixed with iron powder carrier and a fixing test was conducted with a modified FX3500 (Fuji Zerox Co., Ltd.), both showed a sufficient degree of fixing at a roller temperature of 140 ° C.

〔The invention's effect〕

The present invention provides a dry toner in which an inorganic compound is deposited on the surface of a toner by utilizing a precipitation-forming reaction, and the inorganic substance is attached to the outermost layer in a more stable state as compared with a conventional toner having an inorganic substance added thereto. Therefore, it is possible to perform fixing at high speed and efficiently, to prevent caking during storage, to form a uniform image with high fluidity, to prevent filming of the photosensitive pair, and to be excellent in cleaning property. It has the excellent features of being able to obtain stable images over a long period of time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Chiaki Suzuki 1600 Takematsu, Minamiashigara City, Fuji Xerox Co., Ltd. Takematsu Works (72) Inventor Ikutaro Nagatsuka 1600 Takematsu, Minami Ashigara City, Fuji Xerox Co., Ltd. Takematsu Works (56) Reference References JP-A-51-30743 (JP, A) JP-A-53-138736 (JP, A) JP-A-52-136635 (JP, A) JP-A-60-66262 (JP, A) JP-A-60- 198558 (JP, A) JP 62-10654 (JP, A)

Claims (1)

(57) [Claims] 1. A dry toner in which an inorganic compound is deposited on the surface of the toner by a precipitation-forming reaction.