JPH0395563A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To improve the flowability of a toner and developer and to prevent the generation of unequal images by coating at least a part of the surface of fine powder with a compd. having a specific compsn. and resistance. CONSTITUTION:At least a part of the surface of the fine powder of an oxide dielectric material having 0.005 to 3.0mum grain size is coated with the compd. which has <=10<9>OMEGA.cm specific volume resistivity and is expressed by formula. The flowability of the toner and developer is then improved and the generation of the unequal images is obviated. The electrostatic charge quantity of the toner is stably maintained even if the toner is repetitively used. In the formula, n denotes 1 to 6 number; M denotes Fe, Zn, Mg, Mn, Cu, Ba, Ni, Co or Cd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner for developing electrostatic images used in fields such as electrophotography.

More specifically, the present invention relates to a toner for developing an electrostatic image that has good charge stability in a developer tank of -1- and excellent durability with little change in image density.

[Prior Art] Conventionally, as a developer for developing an electrostatic charge image formed on a latent image holding surface of an electrophotographic photoreceptor, a certain bipartite developer and a carrier and a toner have been used. One-part type developers that do not require a carrier are known.

The toner particles constituting these developers are usually colored fine particles containing a resin, a colorant, a charge control agent, and the like.

When a certain developer made of these toner particles is repeatedly used in a plain paper copying machine, etc., there is a problem that the amount of triboelectric charge of the toner becomes unstable, resulting in a decrease in the image quality of copies, a decrease in image density, and fogging. .

Attempts to improve these drawbacks include, for example, a method of coating the carrier with various resins, a method of adding oxide dielectric fine powder such as Si02 as an external additive, and the like.

-2- [Problems to be Solved by the Invention] However, a carrier coated with a resin has a high resistance and therefore has a problem that the etching effect is strong and the solid portion is not uniform. Furthermore, in the case of adding oxide dielectric fine powder, it is possible to improve the fluidity of the developer and obtain image quality without image unevenness, but since the oxide dielectric fine powder itself has a relatively strong charging property, While it is effective in improving the charging characteristics of l-ner,
When added to toners having the same polarity, image density decreases, and when added to toners with opposite polarity, fogging, toner scattering, etc. occur.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems of conventional toners, and its main purpose is to improve the fluidity of toner and developer to prevent image unevenness. The electrostatic charge that maintains the toner charge amount stably during repeated use, that is, maintains a constant image density without causing any change in image density, and does not cause fogging, toner scattering, or contamination of the copied image 3. An object of the present invention is to provide a toner for image development.

[Means for Solving the Problems] However, an object of the present invention is to provide a toner for developing an electrostatic image containing toner particles containing a binder resin and a colorant, and an oxide dielectric fine powder. The particle size of the fine powder is 0.005 to 3.0 μm, and at least a part of the surface of the fine powder has a volume resistivity of 109 ohm-c.
m or less general formula MO-nFe2O3 (where n is a number from 1 to 6, M is Fe, Zn, Mg, Mn, C
This can be easily achieved by toners for developing electrostatic images characterized by being coated with one or more compounds represented by U, Ba, Ni, Co, or Cd.

(Function) The toner of the present invention impairs the effect of improving the fluidity of the oxide dielectric by coating the surface of the oxide dielectric fine powder, which is normally used for the purpose of improving fluidity, with a specific conductive substance. The toner's chargeability is kept stable at all times, making it possible to keep the image density stable for an extremely long period of time, and solving the problem of image quality deterioration. did it. As the oxide dielectric fine powder, known ones are used. For example, Si○2, Ti02, Al2O3, BaTi, which have been widely used as toner fluidity improvers,
03, SrTi03, etc. can be used.

The dielectric material covering the surface of these oxide dielectric fine powders has a volume resistivity of 10" ohm-cm or less and has a general formula M.
O - nFe2Oa (where n is a number from 1 to 6, M is Fe, Zn, Mg, Mn, Cu, Ba
, Ni, Co, or Cd), there is no problem in using oxides, composite oxides, or various combinations thereof. These are appropriately selected depending on the type, particle size, shape, etc. of the oxide dielectric.

In addition, in the present application, the volume resistivity is 1090hm・
Substances with a diameter of cm or less are referred to as conductive substances.

A surface coating method using a conductive substance according to the present invention includes, for example, converting an aqueous solution based on chloride metal ions into complex salt water by a galvanic treatment method, and mixing raw material particles into the metal ion aqueous solution. There is a composite metal oxide surface coating method in which the raw material particles are then neutralized and reduced with an alkali to form a film of metal oxide on the surface of the raw material particles in the form of nuclei. Regardless of the method, a method that can cover at least a portion or the entire surface of the oxide dielectric can be adopted.

The particle size of the oxide dielectric is 0.005 to 3.011 m,
Preferably, the thickness is 0.01 to 1.0 μm. If it is too fine, the charging property will be too high and the roller will not function as a roller to improve the fluidity of the toner. Moreover, if it is too large, a problem of scattering will occur.

The amount of surface coating of the conductive material varies depending on the type and shape of the oxide dielectric material serving as the core and the type of conductive material to be coated, but it is usually 0.01% of the oxide dielectric fine particles of the raw material particles serving as the core. ~50wt%, preferably 0.1-30wt
% is good. If the amount is too small, the effect cannot be achieved, and if the amount is too large, the conductivity becomes too large and the image quality deteriorates.

Various binder resins can be used in the toner structure, such as polystyrene, chlorobolystyrene, poly10-methylstyrene, styrene-rostyrene copolymer, styrene-propylene copolymer, Styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (
Styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid Ester copolymers (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-10-chloroacrylic acid Styrenic resins such as methyl copolymers and styrene-acrylonitrile-acrylic acid ester copolymers (unipolymers or copolymers containing styrene or styrene substitutes), vinyl chloride resins, rosin-modified maleic acid resins, Phenolic resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin,
Ketone resin, ethylene-ethyl acrylate copolymer,
Examples include xylene resins and polyvinyl butyral resins, and particularly preferred resins for use in the present invention include styrene resins, saturated or unsaturated polyester resins, and epoxy resins. Moreover, the above resins are not limited to being used alone, but can also be used in combination of two or more.

The charge control of the toner may be performed using the binder resin or the colorant itself, but if necessary, a charge control agent including known ones may be used. For example, there are nigrosine dyes, quaternary ammonium salts, polyamine resins, etc. for positive charging.
Azo dyes containing metals such as Cr, Co, and A1, metal salts of alkyl salicylic acids, and the like are known for negative charging. The amount used is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight based on 100 parts by weight of the binder resin. The charge control agent may be used in the form of being mixed into the binder resin or attached to the surface of the toner particles.

As the coloring agent, for example, carbon black, Ti02
, In addition to inorganic pigments such as red iron, phthalocyanine blue,
Known organic pigments and dyes such as Diaresin Red, dyes for full color 1 and color, and pigments can be used. The amount used is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the binder resin. In addition, magnetic toners containing magnetic compounds such as magnetite and ferrite 1 are used in an amount of 30% to 50% by weight based on the total weight.
is good.

In the toner for developing an electrostatic image of the present invention, the oxide dielectric fine powder whose surface is coated with a conductive substance contains toner 10.
1 part by weight or less, more preferably 0.0 part by weight
It is preferably added in an amount of 5 to 0.5 parts by weight.

In addition, auxiliary agents such as various plasticizers and mold release agents may be added to the toner for the purpose of adjusting thermal properties, physical properties, etc. The amount added is suitably 0.1 to 10 parts by weight per 100 parts by weight of the binder resin.

A general method for producing toner is as follows.

Resin, colorant, charge control agent, etc. are uniformly dispersed using a Henschel mixer, etc., and this dispersion is melt-kneaded using a kneader, extruder, roll mill, etc. After coarsely pulverizing this with a hammer mill, cutter mill, etc., it is finely pulverized with a jet mill, type mill, etc. Subsequently, the finely pulverized material is classified using a dispersion classifier, a zigzag classifier, or the like. Thereafter, external additives such as oxide dielectric fine powder are dispersed into the classified toner particles using a Henschel mixer or the like.

Further, depending on the case, a treatment may be performed to cause the oxide dielectric fine powder to be embedded into the toner particles to some extent using a hybridizer or the like.

In addition, as carriers used in combination with the electrostatic image developing toner of the present invention in the two-command type developer, iron powder having an average particle size in the range of 2O to 2O0llm, Ferrite 1
・Powder, magnetite 1・Powder, magnetic powder resin 9-10 resin dispersion carrier, etc. can be preferably used. Iron powder, ferrite powder, magnetite powder, etc. may be coated carriers whose surfaces are coated with resin or the like.

The mixing weight ratio of carrier and toner is 100:1 to 10.
is suitable.

[Examples of the Invention] Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

Note that "parts" in the examples represent "parts by weight."

A fine oxide dielectric powder coated with a conductive substance was prepared by the method described below.

Oxide dielectric fine powder (1) 3wt% of Fe304 was attached to the surface of silicon oxide (trade name: Aerosil #200, manufactured by Nippon Aerosil Co., Ltd.) with a particle size of about 12 nm by a wet method based on iron chloride ions. .

Oxide dielectric fine powder (2) 10 wt% of CuO - Fe2O3 is added to silicon oxide (trade name Nipsir SS-150; manufactured by Nippon Silica Kogyo) with a particle size of about 1.3 μm by a wet method using iron chloride ions. It was attached to the lining.

Oxide dielectric fine powder (3): 3 wt % of Fe304 was attached to the surface of titanium oxide (trade name MT500B; manufactured by Teikoku Kako) with a particle size of about 35 nm by a wet method based on iron chloride ions.

Oxide dielectric fine powder (4): 10 wt % of Fe304 was attached to the surface of silicon oxide (trade name: Aerosil R9 72; manufactured by Nippon Aerosil Co., Ltd.) having a particle size of about 16 nm by a wet method based on iron chloride ions.

Example 1 Styrenic resin SBM-600 100 parts (manufactured by Sanyo Chemical Co., Ltd.) Carbon black MA-8 5 parts (manufactured by Mitsubishi Kakai Co., Ltd.) Alkyl salicylic acid glome complex E-81 2 parts (manufactured by Orient Chemical Co., Ltd.) Polypropylene wax 550P 2 Department (
(manufactured by Sanyo Chemical Co., Ltd.) The materials of the above formulation were melted and mixed in a hot roll mill, cooled, and then coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer.

The obtained fine powder was classified to have a particle size of 5 to 2 Oμm. After that, oxide dielectric fine powder (
The material to which 0.3 wt% of 1) was externally added was designated as 1-ner.

Along with 4 parts of this toner, 96 parts of carrier (Ferrai I powder with a particle size of about 100 μm coated with silicone resin) was mixed in a blender to prepare a developer. When we conducted a continuous copying test using this developer using a commercially available dry copying machine that uses selenium as a photoreceptor, we were able to obtain copies with clear image quality and no loss of image density even after 30,000 copies, demonstrating excellent durability. It turned out that it has.

The charge amount of the toner in the developer by the blow-off method is -22.3 pC/g initially and -24.1 pC after 30,000 sheets.
/g.

Comparative Example 1> Of the toner set of Example 1, oxide dielectric fine powder (1
) was changed to Aerosil #2O0, and a toner was produced in exactly the same manner as in Example 1. Hereinafter, a continuous photographing test was carried out using the same operations as in Example 1, but after 10,000 copies, a decrease in image density occurred. The amount of charge of the toner in the developer by the blow-off method is -24.4pc/g at the initial stage of 100
After 00 sheets, the value changed to -28.81 IC/g.

Example 2 Styrenic resin SBM-600 100 parts Carbon black #40 5 parts (manufactured by Mitsubishi Kakai) -13 -14 Nigrosine dyeing N-04 2 parts (
Orien 1 (manufactured by Kagaku) Polypropylene wax 550P 2 parts (manufactured by Sanyo Chemical) Using the above guidelines, oxide dielectric fine powder (2) 0.
l・
We created a ner.

To 4 parts of this toner, 9 G parts of carrier (fluorine resin-coated fly-1 powder having a particle size of about 100 μm) was mixed in a V-blender to obtain a developer. Using this developer, we conducted a continuous copying test using a dry copying machine using a commercially available organic photoconductor as a photoreceptor, and even after 30,000 copies, copies with clear image quality and no decrease in image density were obtained.
It was found to have excellent durability.

}1? of 1・ner in the developer by blow-off method. The amount of electricity is initially +2O. +21 after 30,000 sheets at 111C/g
．． It was 611C/g.

Comparative Example 2> Oxide dielectric fine powder (2) in the toner set of Example 2
Example 2 except that the nib seal was changed to 88-50.
L-ner was prepared in exactly the same manner as described above. Below, Example 2
I performed a continuous live-action test using the same operation as , but it was soooo
After printing, the image quality deteriorated and fog became severe. The amount of charge of the toner in the developer by the blow-off method is initially +17
．． It was 8 pC/g, and after 8000 sheets, it was +11.2 pC/g.

Example 3> Styrenic resin SBM-600 100
4 parts carbon black MA-8 (
(manufactured by Mitsubishi Kasei) Nigrosine dye N-07 2 parts (manufactured by Orient Chemical) Polypropylene wax 550P 2 parts (manufactured by Sanyo Kasei) Using the above guidelines, oxide dielectric fine powder (3) 0.
A toner was produced in the same manner as in Example 2 except that 3 wt% was added externally.

Hereinafter, continuous live-action test I
As a result, it was found that even after 30,000 copies, copies with clear image quality and no decrease in image density were obtained and had excellent durability. The charge amount of the toner in the developer by the blow-off method is initially → -19.61 lC/g and 30
After 000 sheets +2O. It was 9 pC/g.

<Comparative Example 3> Oxide dielectric fine powder (3) in the toner composition of Example 3
Example 3 except that titanium oxide MT500B was used.
A toner was prepared in the same manner. Hereinafter, a continuous photographing test was carried out using the same operations as in Example 3, but after 10,000 sheets, image quality deterioration such as density unevenness occurred.

The amount of charge of the toner in the developer by the blow-off method is initially +
At 16.3 pC/g, after 10,000 sheets → -1.4.0
It's pC/g.

Example 4> Polyester resin 100 parts (Mw
/Mn. =13000/6000) Anthraquinone dye 5 parts (C.I. Solven
t Red 52) Charge control agent E-81
2 parts (Orien 1, Kagaku Co., Ltd.) Using 2 parts, oxide dielectric fine powder (4) 0
．． A toner was produced in the same manner as in Example 1, except that 4 wt% was externally added.

Hereinafter, a continuous photocopying test was carried out in the same manner as in Example 1, and it was found that even after 30,000 copies, copies with clear image quality and no decrease in image density were obtained and had excellent durability. The charge amount of the toner in the developer by the blow-off method is initially -26.411Clg, which is 30,000.
After the sheet, it was -25.2 pC/g.

Comparative Example 4> Of the toner composition of Example 4, oxide dielectric fine powder (4)
A toner was produced in the same manner as in Example 4 except that the toner was changed to Aerosil R972. Hereinafter, a continuous photographing test was carried out using the same operations as in Example 4, but a decrease in image density occurred after 3,000 copies.

The amount of charge of the toner in the developer by the blow-off method is initially -
-37. after 3000 sheets at 21.7 pC/g. OllC/
It was g.

[Effects of the Invention] As stated above, the electrostatic image developing toner 17-18 of the present invention improves the Yj conductivity of the toner by lowering the resistance of the surface of the externally polished oxide dielectric fine powder. The fluidity of the toner and developer is increased without impairing the image quality, and there is no deterioration in image quality such as brush lines.Therefore, if the toner for developing electrostatic images of the present invention is used, a developer with high durability over a long period of time can be obtained. Therefore, the present invention can provide an industrially useful toner for developing a charge image.

Claims (1)

[Claims] (1) In an electrostatic image developing toner containing toner particles containing a binder resin and a colorant and an oxide dielectric fine powder, the particle size of the oxide dielectric fine powder is 0.005 to 3.0.
μm, and at least a part of the surface of the fine powder has a volume resistivity of 10^9 ohm・cm or less with the general formula MO・nF
e_2O_3 (where n is a number from 1 to 6, M is Fe
, Zn, Mg, Mn, Cu, Ba, Ni, Co or Cd
A toner for developing an electrostatic image, characterized in that it is coated with one or more compounds represented by: