JPS63101854A - Electrostatic charge image developer - Google Patents

Abstract

PURPOSE:To prevent agglomeration of a toner powder and to restrain staining of a carrier and the surface of a photoconductive layer by using a toner containing polymethylsilsesquioxane powder having negative electrification characteristics. CONSTITUTION:The toner contains the polymethylsilsesquioxane (A) powder having negative electrification characteristics. The preferable component A is obtained by hydrolyzing and condensing methyltrialkoxysilane or its hydrolyzed and partially condensed product in an aqueous solution ammonia or aminies, and it is preferred for each particle to be independent of each other and to have an almost true spherical form. The addition of the component A permits almost all of agglomeration of the toner particles to be prevented, staining of he carrier and the surface of the photoconductive layer to be remarkably restrained, and consequently, always fog-free sharp images to be obtained.

Description

[Detailed Description of the Invention] [Detailed Description of the Invention] The present invention relates to an electrostatic charge image developer, and more particularly to an electrostatic charge image developer that can clearly develop an electrostatic charge image without fogging and has extremely stable development characteristics. Regarding developer.

[Technical background of the invention and its problems] As is well known, in electrophotography, a required electrostatic charge image or electrostatic charge pattern (latent image) is formed on the surface of a photoconductor, and on this electrostatic latent image, A developer containing a colored powder (toner) having an opposite charge is brought into contact and the toner is deposited to form a visible image. By the way, the visualization, that is, development, of the electrostatic charge image is carried out by a cascade development method using a mixed developer of toner and carrier, or by a magnetic brush development method.
Alternatively, it is carried out by a fur brush development method, a touchdown development method, etc. using a developer consisting only of toner.

However, with these conventional development methods, deterioration of the developer due to contamination of the carrier surface (development characteristics are likely to be impaired), or development problems due to the scavenging effect of the developed image or lack of the development electrode effect. Disadvantages include that the photoconductor surface (photosensitive surface) is easily contaminated due to poor image quality or poor transfer characteristics of the developed image.

In order to solve these problems, there are electrostatic image developers having a total oxide powder or a silicon dioxide powder as a component of the toner. However, when mixing these totally bent oxide powders or silicon dioxide powders with resin and carbon black, which are the base resin of powder toner, it takes a long time to disperse them, and the produced toner powders tend to aggregate. There is room for improvement in terms of ease of transfer and transfer characteristics.

[Object of the invention] The present invention has excellent workability during toner production,
In addition, an electrostatic image developer made of a toner that hardly causes aggregation between toner powders, can significantly suppress the occurrence of contamination on the carrier or photoconductor surface, and exhibits strong negative charging characteristics. The purpose is to provide

[Configuration of the Invention] The electrostatic image developer of the present invention is characterized by comprising a toner containing polymethylsilsesquioxane powder having negative charging characteristics.

The polymethylsilsesquioxane powder, which is a component of the toner of the present invention, has good dispersibility in resin during toner production, has extremely low agglomeration, and has excellent fluidity. The polymethylsilsesquioxane used in the present invention is obtained by hydrolysis condensation of methyltrialkoxysilane or its hydrolysis/partial condensate in an aqueous solution of ammonia or amines. The thing is chlorine atom,
It is preferable because it has almost no impurities such as alkaline earth metals and alkali metals, and it is spherical and has excellent free flow properties.In particular, it is preferable that the particles are independent and almost perfectly spherical, giving the toner excellent flow properties. This is preferable in that it can provide the following properties.

Although the average particle diameter of such polymethylsilsesquioxane powder is not particularly limited, it is preferably 0.1 to 1O-.

Such polymethylsilsesquioxane powder has strong negative charging characteristics. This polymethylsilsesquioxane powder can be used as it is as a raw material for the toner of the present invention, and in order to treat hydroxyl groups remaining on the powder surface and adjust the amount of negative charge, organotrialkoxysilane It is also possible to use a surface treated with a silicon compound such as methyldisilazane or a titanium compound such as tetrabutyl titanate and/or a hydrolyzed condensate thereof.

The toner constituting the developer of the present invention contains the thus obtained polymethylsilsesquioxane powder having negative charging characteristics, a resin serving as a binder, a colorant, and other components as necessary. It can be obtained by blending, kneading until uniform, then crushing and classifying. Incidentally, when producing such a toner, the surface treatment of the polymethylsilsesquioxane powder and the production of the toner can be carried out simultaneously by blending a surface treatment agent such as the above-mentioned silicon compound or titanium compound.

The content of polymethylsilsesquioxane powder in such a toner is not particularly limited, but is approximately 0.1 to 40% by weight. If the content of polymethylsilsesquioxane powder is too small, the positive charging characteristics will be poor.
If the content is too large, it becomes difficult to prepare the toner.

The electrostatic image developer of the present invention can be composed of only the above-mentioned toner, but it can also be composed of a mixed system with a carrier such as glass beads or iron powder.

[Effects of the Invention] As explained above, according to the developer of the present invention in which polymethylsilsesquioxane powder having negative charging characteristics is used as a component of the toner, the electrostatic charge image (
It can develop electrostatic patterns or latent images into clear, fog-free images. Therefore, it becomes easy to adhere to the electrostatic image surface, and thereafter not only shows good transfer characteristics, but also has an abrasive effect on the adhesion of toner to the photoconductor surface and carrier. Therefore, clear images without fog can always be obtained during development.
Moreover, the developer of the present invention can maintain and exhibit predetermined development characteristics over a long period of time. Therefore, the developer according to the present invention has the advantage of being able to obtain the above-mentioned clear images, greatly suppressing contamination of the photoconductor surface compared to conventional developers, and being easy to clean. It can be said that it brings many advantages.

[Examples] The present invention will be described below with reference to Examples. In addition, all "r parts" in Examples represent "parts by weight."

Production Example 1 4.000 parts of water and 50 parts of a 28% ammonia aqueous solution were charged into a 4-tube flask equipped with a thermometer, a reflux device, and a stirrer, and stirred for 10 minutes at 100 R, P, and an oven to form a uniform ammonia aqueous solution. To this ammonia aqueous solution, add 60 methyltrimethoxysilane of 10 ppi+ in terms of chlorine atom.
0 part was quickly added to the ammonia aqueous solution while rotating the stirrer at 5 r, p, m so as not to mix, so that a two-layer state was formed: a methyltrimethoxysilane layer in the upper layer and an ammonia aqueous solution layer in the lower layer. Next, the stirring speed of the stirrer was set to 2 Or, p, m, and while maintaining the two-layer state, the hydrolysis reaction proceeded at the interface between methyltrimethoxysilane and the ammonia aqueous solution. As the reaction progressed, the reactants It gradually settled to the lower layer, and the lower layer became cloudy due to floating reactants, and the upper methyltrimethoxysilane layer gradually became thinner and disappeared in about 3 hours (confirmed visually). maintained at ~60°C,
After stirring for 3 hours under the same conditions, the precipitated product was cooled to 25°C and passed through a 100-mesh wire mesh.
It was dehydrated by centrifugation to form a cake, and the cake layer was dried in a drying oven at 200°C. This was crushed using a lab jet to obtain a white powder.

When the polymethylsilsesquioxane powder thus obtained was observed with an electron microscope, it was found to be almost perfectly spherical with a particle size ratio of 1.0 to 1.2. The diameter was about 1.9μ.

Production Example 2 The amount of the 28% ammonia aqueous solution in Production Example 1 was reduced to 1
00 parts, the stirring speed after forming a two-layer state was 3 Or, p,
True spherical polymethylsilsesquioxane powder with an average particle diameter of 3.0-m was obtained in the same manner as in Production Example 1, except that the particle size was changed to m.

Production Examples 3 and 4 200 parts of the polymethylsilsesquioxane obtained in Production Example 2 was weighed into a cylindrical glass flask, stirred to uniformly disperse it, and then the temperature inside the flask was lowered to 80°C. ℃
was held at Surface treatment agent solution 20 with the compounding ratio shown in Table 1
After 6 drops were added over 2 hours while stirring the inside of the flask, the temperature inside the flask was raised to 150°C, and while maintaining this temperature, the pressure was reduced to room ■ Hg, and unnecessary substances such as methanol were removed. was removed. After methanol and the like were completely removed, stirring was further performed at 150° C. for 2 hours to obtain surface-treated polymethylsilsesquioxane powder.

Production Example 1
It was measured in the same manner. The results are shown in the table.

Example 1 Epoxy resin Epicoat 1 was added to 20 parts of the surface-treated polymethylsilsesquioxane powder obtained in Production Example 1.
004 (manufactured by Shell, trade name) and 10 parts of carbon black were added and mixed and blended at 100° C. for about 2 hours. After cooling, the kneaded material was crushed and classified to obtain a powder toner having a diameter of 5 to 20 mm. This toner is housed in a Faraday cage consisting of a metal cylinder whose one end is sealed with a 300-mesh wire mesh, and high-pressure gas is blown from the other end to measure the amount of contact charge when the toner is removed through the wire mesh. When measured (blow-off method), the toner showed clear negative charge.

When the above toner was adhered to a bar magnet and the surface of the organic photoconductor having a positive electrostatic charge image was developed by a so-called magnetic brush development method, a clear positive image was obtained, and the positive image had good transfer characteristics.

Example 2 10 parts of carbon black was added to 100 parts of a styrene-acrylic (70:30) copolymer having a melting point of 120°C, followed by hot kneading, pulverization, and classification. 5 parts of the polymethylsilsesquioxane powder obtained in Production Example 2 was added and mixed per 100 parts of the thus obtained particle size of 5 to 20, and the mixture was heated to 50 to 70°C and housed in a rotating metal cylinder. Thereafter, a toner was prepared by mixing once. When this toner was observed using a scanning electron microscope, it was found that the surfaces of the resin-carbon black particles were almost uniformly coated with the surface-treated polymethylsilsesquioxane powder.

A developer was obtained by mixing 5 parts of the above-prepared toner and 100 parts of iron oxide powder with a particle size of 100 -, and the charge amount of this developer was measured by the blow-off method as in Example 1. It showed a charge of . Further, when a positive electrostatic charge image on an organic photoconductor was developed by a magnetic brush method using this developer, a clear black positive image was obtained. This developed image had excellent transfer characteristics, and the photoconductor was easy to clean, and no change in the properties of the developer or the photoconductor was observed even after 30,000 copies were made.

Comparative Example 1 The same procedure was carried out except that instead of the polymethylsilsesquioxane powder obtained in Production Example 3, 7 Aerosil 130 (fumed silica; trade name, manufactured by Nippon Aerosil Co., Ltd.) treated at a ratio of 5 parts was used. A toner was prepared in the same manner as in Example 2, and development was carried out in the same manner. Although the developed imager exhibited a negative charge, cleaning of the photoconductor surface became difficult after 10,000 copies.

Example 3 A mixture of 100 parts of epoxy resin Nippyfu 1004 (manufactured by Shell, trade name), 80 parts of acicular γ-ferrite powder with a particle size of 0.1 to 0.3, and 5 parts of carbon black was mixed into 1
The mixture was heat-kneaded at 00°C for about 3 hours. Production Example 3 per 100 parts by weight of powder with a particle size of 5 to 20 obtained by finely pulverizing and classifying after cooling.
Add 10 parts of polymethylsilsesquioxane powder obtained from
Hot air (80 cm
A toner consisting of edge-shaped particles was prepared by dropping the toner into a metal cylinder through which a temperature of ~90° C.) was flowing.

When a positive electrostatic charge image on zinc-sensitive paper was developed by a magnetic brush method using a developer consisting only of toner thus obtained, a clear black positive image was obtained. The transfer characteristics of this developed image to plain paper were extremely good, and cleaning of the photosensitive surface after transfer was easy.

Example 4 80 parts of a styrene-acrylic copolymer having a melting point of 120°C and 5 parts of phthalocyanine blue were added to the polymethylsilsesquioxane powder obtained in Production Example 4, and the mixture was heat-kneaded at 120°C for about 3 hours. After cooling this mixed wire material, it is crushed and classified.
A toner having a particle size of 5 to 20% was obtained.

Two parts of the toner thus obtained were mixed with 100 parts of iron balls having an average particle size of 300 μm to prepare a developer.

When a positive electrostatic charge image on an organic photoconductor was developed using this developer by a cascade method, a clear blue positive image was obtained. This developed image had excellent transfer characteristics, and cleaning of the photoconductor surface after transfer was extremely easy, and almost no change was observed in the developed image even after 60,000 copies were made.

Comparative Example 2 A toner was prepared in the same manner as in Example 4, except that 20 parts of talc with an average particle size of 1741+ was used instead of the polymethylsilsesquioxane powder obtained in Production Example 4, and the same method was used. Developed with. The results also showed that the developer was negatively charged, but after 30,000 copies, the cleaning performance of the surface of the photocharger became poor.

Claims (2)

[Claims] (1) An electrostatic image developer comprising a toner containing polymethylsilsesquioxane powder having negative charging characteristics. (2) The electrostatic image developer according to claim 1, wherein the particles of polymethylsilsesquioxane powder are independent, substantially spherical polymethylsilsesquioxane powders.