JPH0562327B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to positively chargeable color toners for developing negatively electrostatically charged images formed in electrophotography.

Conventional technology and problems Conventionally, in electrophotography, positively charged toner and iron powder, etc. are used to develop negatively electrostatically charged images formed on photoreceptors such as zinc oxide (ZnO) and organic photoconductors. A positively chargeable two-component developer is used, which is a mixture of a carrier and a carrier. In this case, the positively chargeable toner is usually obtained by melt-kneading a resin, a colorant, and a charge control agent, and then finely pulverizing the mixture, and a nigrosine dye is generally used as the charge control agent.

However, when producing a positively chargeable color toner, clear color tones such as red, blue, yellow, etc. are required, so the nigrosine dye having a black color tone cannot be used.

In order to avoid such color disturbances caused by the charge control agent, for example, JP-A-58-211763 uses colorless calcium stearate as the charge control agent, and uses a mixture of this, a resin, and a coloring agent. toner is suggested. However, in this case, although a clear toner color tone can be obtained, there are problems such as an increased tendency of the toner to agglomerate, poor fluidity, and the possibility of toner filming on the photoreceptor. However, the drawback was that it lacked durability for long-term use.

On the other hand, many of the colorants themselves have inherent triboelectric charging properties, which causes problems such as variations in the amount of charge of the toner and adversely affects stability during continuous use.

Purpose of the Invention The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a positively chargeable color toner having vivid red, blue, yellow, etc. tones. It is in.

Another object of the present invention is that the amount of toner charge is uniform and stable for a long period of time, so that the toner can be positively charged without deteriorating image quality such as fogging or brush marks or contaminating the inside of the device due to toner scattering during high-speed copying or continuous copying. Our goal is to provide color toner.

Structure of the Invention To achieve the above object, the positively chargeable color toner of the present invention is characterized in that it is composed of at least a resin and a colorant, and the colorant is surface-treated with a metal soap.

Various known resin components can be used as the resin component of the color toner of the present invention. For example, polystyrene or styrene-acrylate copolymer,
Alternatively, styrene-methacrylate copolymers, epoxy resins, polyester resins, etc. may be mentioned.

Furthermore, various known dyes and inorganic or organic pigments can be used as coloring agents as other constituent components. Particularly suitable are organic pigments. in particular,
Examples include soluble and insoluble azo pigments such as β-naphthol type and naphthol AS type, phthalocyanine type pigments, perylene pigments, quinacridone pigments, and condensed polycyclic pigments such as dioxazine pigments.

The positively chargeable color toner of the present invention includes at least a resin and a colorant such as the above-mentioned organic pigment whose surface is treated with a metal soap as essential components.

The metal soap used in the present invention refers to metal salts such as fatty acids and resin acids, and specifically includes fatty acids such as stearic acid, oleic acid, and abietic acid, and aluminum, calcium, and resin acids.
Examples include metal salts such as zinc, barium, and magnesium.

Various methods can be considered for treating the surface of a colorant such as an organic pigment with a metal soap in order to fix the metal soap to the surface of the colorant. After adding and mixing an aqueous alkaline acid solution, a metal salt solution containing a necessary metal is further added to deposit a desired metal soap on the surface of the pigment particles. Then, the particle size may be adjusted by purifying, drying, and crushing.

In the present invention, the metal soap contains, per colorant,
About 0.5 to 20% by weight, preferably 1 to 20% by weight, on its surface
It is recommended that the content be 10% by weight. If the content of the metal soap is higher than the above range, agglomeration and fusion may easily occur during storage or continuous use of the toner.
Further, filming tends to occur on the surface of the photoreceptor, which is undesirable. In addition, if the content is less than the above range, the surface treatment of the colorant by the metal soap will be insufficient and uneven, resulting in a lack of stability in the amount of charge on the toner, resulting in image quality deterioration during continuous use, etc. This is not preferable as it tends to cause

In the positively chargeable color toner of the present invention, 1 to 20 parts by weight, preferably 3 parts by weight of the colorant surface-treated with the metal soap, is added to 100 parts by weight of the resin.
It is preferable to use up to 10 parts by weight. Further, in order to adjust the color tone, two or more types of colorants treated with metal soap may be used in combination. In this case, the total amount used is preferably within the above range.

The positively chargeable color toner of the present invention may contain a known colorless or light-colored charge control agent, if necessary. Examples of this type include quaternary ammonium salts, polyamine resins, amino group-containing styrene resins, and amines such as acetoguanamine. The amount used is 100 resin.
A suitable amount is about 0.1 to 10 parts by weight.

In addition, additives such as a low molecular weight olefin polymer and finely powdered silica may be included as constituent components of the positively chargeable color toner of the present invention in order to improve fixing properties and fluidity.

The toner may be produced by kneading the above-mentioned components using a kneader or the like, cooling, pulverizing, and classifying. The average particle size of the toner is preferably 5 to 20 microns.

There are no particular restrictions on the carrier used in combination with the positively chargeable color toner of the present invention, but 10
Particularly preferred are iron powders with an average particle size of ~200 microns. In this case, it may be a so-called coated carrier coated with a fluororesin or the like for the purpose of improving durability during continuous use. Also, the mixing weight ratio of carrier and positively chargeable color toner is
100:1 to 10 is good.

Examples of the invention The following will explain the invention using examples.
indicates "parts by weight".

[Example 1] Styrenic resin (SBM-600, manufactured by Sanyo Chemical Co., Ltd.)
A coloring agent sample obtained by surface treating 100 parts of Dialite Red FGR (manufactured by Mitsubishi Chemical Industries, Ltd.) with zinc stearate (approximately 3% by weight of zinc stearate)
A red toner having an average particle size of about 12 microns was obtained by blending, kneading, pulverizing, and classifying 4 parts of the above powder.

A developer was prepared by mixing and stirring 5 parts of this toner and 100 parts of a fluororesin coating carrier having an average particle size of about 70 microns. The charge amount of this developer was measured by the blow-off method and was found to be 23 μC/g.

Next, when this developer was used for development in a copying machine using zinc oxide as a photoreceptor, very clear red copies were obtained.

Furthermore, when testing the durability of this developer by continuously copying approximately 10,000 sheets, it was found that there was almost no deterioration in image quality such as fogging or brush lines, or contamination within the device due to toner scattering. Furthermore, the developer charge amount was extremely stable at 22 μC/g.

[Example 2] A red toner and a developer were prepared in exactly the same manner as in Example 1 using "Dia Light Trend FGR" containing about 10% by weight of zinc stearate. The average particle size of the toner was approximately 14 microns. The amount of charge of the developer was 28 μC/g.

Next, when this developer was used for development in a copying machine using an organic photoconductor as a photoreceptor, extremely clear red copies were obtained.

Furthermore, we conducted a continuous test of approximately 10,000 sheets to examine the durability of this developer, and found that there was almost no deterioration in image quality or contamination within the device. Further, toner filming did not occur. The developer charge amount was also extremely stable at 30 μC/g.

[Example 3] In addition to the resin and colorant samples in Example 1, colorless 4
A red toner having an average particle size of about 10 microns was prepared in the same manner as in Example 1, except that 3 parts of grade ammonium salt ("Bontron P-51", manufactured by Orient Chemical Co., Ltd.) was added.

4 parts of this toner and 100 parts of iron oxide powder with an average particle size of about 100 microns were mixed and stirred to obtain a blow-off charge amount.
A developer of 19 μC/g was obtained.

Next, evaluation was carried out in exactly the same manner as in Example 1, and extremely clear red copies were obtained without deterioration in image quality or contamination within the apparatus through approximately 10,000 copies. The developer charge amount was also stable at 17 μC/g.

[Comparative Example 1] 100 parts of styrene resin (SBM-600) and “Dialyte Red” which is not treated with zinc stearate
A red toner and a developer were prepared in exactly the same manner as in Example 1.The average particle size of the toner was about 12 microns.
The amount of charge of the developer was 18 μC/g.

Next, evaluation was carried out in exactly the same manner as in Example 1, and after about 2000 sheets, fogging, scratches, etc. increased rapidly, and image quality deteriorated. In addition, the interior of the device was so contaminated by toner scattering that it became almost unusable. Also, the amount of charge on the developer at that time is
It was halved to 9μC/g.

[Comparative Example 2] 100 parts of styrene resin "Dialite Red"
A red toner and a developer were prepared in exactly the same manner as in Example 1 by mixing and kneading 4 parts of "FGR" and 3 parts of zinc stearate.The average particle size of the toner was about 12 microns. The amount of charge is
It was 21μC/g.

Next, evaluation was performed in exactly the same manner as in Example 1, and it was found that the fluidity of the toner and developer was poor from the beginning, and the image quality of the resulting copies was low in image density, uneven, and unclear. In addition, the image quality tends to deteriorate with continuous use, and it becomes almost unusable after about 2,000 sheets.

[Example 4] In Example 1, a coloring agent sample (containing about 5% by weight of calcium abietate) obtained by surface treating "Hostapalm Blue A3R" (manufactured by Hoechst) with calcium abietate was used. A blue toner and developer were prepared in exactly the same manner as in Example 1. The average particle size of the toner was approximately 12 microns. The amount of charge of the developer was 26 μC/g.

Next, images were produced and evaluated in exactly the same manner as in Example 1, and very clear blue copies were obtained with almost no image quality deterioration or toner scattering through approximately 10,000 copies. Also, the amount of charge on the developer
It was stable at 24μC/g.

Effects of the Invention As described above, the positively chargeable color toner of the present invention has a uniform charge amount and is stable. Therefore, if a developer is formed using the positively chargeable color toner of the present invention, extremely clear and high-quality images can be obtained.
Furthermore, it is possible to obtain a long-life developer with less contamination inside the copying device due to toner scattering.

Claims (1)

Claims: 1. A positively chargeable color toner comprising at least a resin and a colorant, the colorant being surface-treated with metal soap. 2. The coloring agent may be added to the metal soap in an amount of about
2. The positively chargeable color toner according to claim 1, wherein the positively chargeable color toner has a content of 0.5 to 20% by weight. 3. The positively chargeable color toner according to claim 1, wherein the colorant is an organic pigment.