JP2715303B2 - Magenta toner for full color image formation - Google Patents

Description

The present invention relates to a color toner used for full-color electrophotography, and particularly to a full-color copying machine using a heat roller fixing device having a silicone rubber roller and a Teflon controller. The present invention relates to a magenta toner suitable for full-color image formation.

[Prior Art] The required quality required of a coloring material of a magenta toner for color electrophotography is 1) excellent spectral reflection characteristics (color characteristics), that is, having a clear magenta color, and 2) good dispersibility in a resin. 3) Excellent stability to light, that is, good light fastness of the copy, 4) Matching the functions required of the full-color copier, and not giving significant side effects. For example, there are adhesion to the surface of the fixing roller and dyeing properties.

Conventional magenta colorants for color electrophotography include quinacridone pigments, thioindigo pigments, xanthene dyes, anthraquinone dyes, and azo dyes.

For example, JP-B-49-46951 describes 2,9-dimethylquinacridone pigments, JP-A-55-26574 relates to thioindigo pigments, and JP-A-59-57256 discloses xanthene dyes. There is a description about. JP-B-55-42383 describes an anthraquinone dye. Furthermore, in Japanese Patent Publication No. 53-47147, the present applicant has proposed a magenta toner in combination with an appropriate binder resin using a quinacridone-based or rhodamine-based colorant. However, none of the colorants satisfies all of the characteristics 1) to 4), and each has a strength and a disadvantage. for that reason,
It is very difficult to rely on a single dye or pigment as a magenta colorant, and it is practical to use two or more colorants in combination to compensate for the disadvantages of each colorant.

For example, the present applicants have proposed a magenta toner using two oil-soluble dyes as disclosed in JP-A-57-130044 and JP-A-57-130046. This magenta toner has a vivid color tone and excellent saturation, but on the other hand, one of the dyes contains a component that contaminates the silicone rubber used in the heating roller fixing device, so that it is gradually produced by continuous copying. The fixing silicon roller is dyed, and finally, a so-called offset phenomenon in which the toner is fused to the heating roller is caused. Also, the combination of these oil-soluble dyes is effective in reducing the toner charge rather than increasing it. Therefore, charge under low temperature and low humidity
Up can be sufficiently prevented, and a preferable image density can be guaranteed. However, conversely, the toner scatters due to insufficient charging under high temperature and high humidity, thereby contaminating the inside of the apparatus, and fogging due to the low-charged toner to easily cause image contamination.

[Problems to be Solved by the Invention] However, an object of the present invention is to provide a magenta toner for forming a full-color image which has solved the above-mentioned disadvantages.

That is, an object of the present invention is to provide a magenta toner for forming a full-color image, which can provide a clear color, has a large coloring power, and is excellent in light resistance.

Still another object is to provide a magenta toner for full-color image formation that does not deteriorate the dyeing of a silicone rubber roller or the like during fixing.

Another object of the present invention is to provide a magenta toner for forming a full-color image having a charging characteristic having excellent environmental stability.

Another object of the present invention is to provide a magenta toner for forming a full-color image which is less likely to be spent on a carrier even by repeated copying.

[Means and Actions for Solving the Problems] Specifically, the present invention provides at least a binder resin, a quinacridone-based organic pigment and a xanthene-based dye, and an anthraquinone-based magenta dye or alkyl as a negative charge control agent. A magenta toner for forming a full-color image containing a metal chelate of salicylic acid, wherein a combined amount of a quinacridone-based organic pigment and a xanthene-based dye is a binder resin.
2 to 20 parts by weight with respect to 100 parts by weight, the addition ratio of the quinacridone-based organic pigment and the xanthene-based dye is 100: 3 to 1
00:20, which relates to a negatively charged magenta toner for full-color image formation.

The quinacridone-based organic pigment is a high-grade pigment having a slightly reddish color and excellent in light resistance and charge stability, but does not have sufficient performance as a magenta color when added alone. That is, with respect to the hue, the reflection in the bluish portion is less than the ideal magenta color, and the hue is reddish. It also has disadvantages such as poor chroma and inadequate vividness with respect to sharpness. Therefore, when used alone, the quality of color reproducibility is insufficient. However, when it is used as a toner, it has preferable characteristics in that carrier contamination due to repeated copying is small.

On the other hand, the xanthene-based dye is a so-called rhodamine-based dye, and is a colorant that emits fluorescence and exhibits a clear blueish pink color. This dye is also used as a magenta color when used alone, but has features such as obtaining a clear color and having a large coloring power. However, it has poor light resistance and has a disadvantage of fading in a short time, so that the amount of addition cannot be increased. This feature of rhodamine-based dyes must be fully considered since recent full-color copies are used for various applications and light fastness is a very important item.

That is, the present inventors used a xanthene dye having excellent hue clarity in combination with a hue, which is a defect of the quinacridone pigment, and a sharpness, to compensate for the hue, chroma, light fastness and chargeability and repeated copying. An object of the present invention is to provide an excellent magenta toner that does not deteriorate. The amount of the colorant added in the present invention is 2 to 20 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of the total colorant. The addition ratio of the quinacridone pigment and the rhodamine dye is such that the quinacridone pigment / rhodamine dye = 100/3 to 100/20, preferably 1
00/3 to 90 / 5.1.

When the ratio of the rhodamine-based dye is increased to 100/20 or more, light resistance and roller dyeability deteriorate, and when the ratio is reduced to 100/3 or less,
Hue and sharpness deteriorate.

Representative examples of quinacridone organic pigments include: and so on. Among them, 5. CI Pigment Red 122 is particularly suitable as a colorant for magenta.

Also, as typical examples of xanthene dyes, Is mentioned.

Each of Nos. 6 to 8 has a clear bluish pink color.

Because 6,7 is a basic dye, it has some hygroscopicity,
In consideration of the compatibility with the resin, in the present invention,
Oil-soluble, excellent compatibility with resin, high coloring power
CISolvent Red 49. is particularly suitable.

As the binder resin applied to the toner of the present invention, all known resins can be used. For example, polystyrene, poly-p-chlorostyrene, a homopolymer of styrene such as polyvinyltoluene and a substituted product thereof, styrene-p- Chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethacrylic acid Methyl copolymer, Styrene-acrylonitrile copolymer, Styrene-vinyl methyl ether copolymer, Styrene-vinyl ethyl ether copolymer, Styrene-vinyl methyl ketone copolymer, Styrene-butadiene copolymer, Styrene-isoprene copolymer Styrene-based copolymers such as polymers, styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, styrene-maleic acid ester copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, and polyacetic acid Vinyl, poly Tylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyamide, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, Chlorinated paraffin, paraffin wax or the like can be used alone or as a mixture. Preferably, the binder resin is an unsaturated polyester resin, as shown in the examples below.

Furthermore, the magenta toner of the present invention contains an anthraquinone-based magenta dye or a metal chelate of alkyl salicylic acid as a negative charge control agent.

When a carrier is used for the developer, a conventionally known carrier can be used. For example, magnetic materials such as iron, cobalt, and nickel, and alloys and mixtures thereof, or coatings on the surfaces thereof.

Further, for the developer in which the toner of the present invention is used,
It is preferable to add a charge control agent such as colloidal silica or a fluidity modifier to the toner in an amount of about 0.01 to 5% by weight (preferably 0.1 to 2% by weight).

A general method for producing a magenta toner containing the dye of the present invention is as follows.

The resin and the colorant (charge control agent in some cases) are uniformly dispersed with a Henschel mixer or the like.

The dispersion is melt-kneaded with a kneader, extruder, roll mill or the like.

The kneaded material is roughly pulverized by a cutter mill, a hammer mill, or the like, and then finely pulverized by a jet mill, an I-type mill, or the like.

 The finely pulverized material is classified by DS and a zigzag classifier.

In some cases, silica or the like is dispersed in the classified material using a Henschel mixer or the like.

Further, the colorant of the present invention can also be used in a toner polymerized by a suspension polymerization method.

[Examples] Hereinafter, the present invention will be described in detail with reference to Examples.

Example 1 The above formulation was melt-kneaded in a roll mill, cooled, finely pulverized in a jet mill, and classified to obtain a negatively-charged magenta toner having a volume average particle size of 12 μm. To this negatively charged magenta toner, 0.5% by weight of hydrophobic silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was externally added using a Henschel mixer to obtain a magenta toner. This toner concentration carrier (resin-coated ferrite powder, average particle size 70μ) is mixed with
% Developer. Using this developer, a full-color copying machine equipped with a full-color electrophotographic apparatus having a magenta developing device, a cyan developing device, a yellow developing device, and a black developing device having the OPC photosensitive drum shown in FIG. A copy test was performed using a machine [(CLC-1, trade name) manufactured by Canon Inc.].

The obtained copy had satisfactory color tone (hue and saturation), light fastness, and roller dyeability.

In order to examine the environmental characteristics of the negatively charged magenta toner, the charge amount was measured under high temperature, high humidity, and low temperature, low humidity. The values were almost unchanged at -18.4 μC / g and -15.2 μC / g, respectively.
Approximately the same desirable image density was obtained.

Also, even in a 30,000-sheet copy durability test, almost no image deterioration was observed.

Example 2 0.9 × 100 / 5.1 based on 100 parts by weight of quinacridone pigment
= 90 / 5.1 (≒ 17.6) A negatively chargeable magenta toner having a volume average particle size of 10 μm was prepared and evaluated in the same manner as in Example 1 by using the above-mentioned formulation using a xanthene dye in an amount of 1 part by weight. The color, light fastness, and roller dyeability were also satisfactory.

Comparative Example 1 A toner was prepared with the above formulation in the same manner as in Example 1,
evaluated. In the color of the copy, the hue was shifted to the red side, the saturation was inferior, the color tone was considerably dull, and a clear magenta color could not be obtained.

Comparative Example 2 A toner was prepared with the above formulation in the same manner as in Example 1, and evaluated. The hue was a slightly dull magenta color. Regarding the light fastness, fading was observed even after only 10 hours with a fade meter, and the product did not reach the commercial level. Further, continuous copying was performed with a copying machine, but the fixing roller began to dye magenta around 5,000 sheets after the start of copying, and hot offset occurred on 7,000 sheets. Observation of the fixing roller revealed remarkable dyeing. Further, microscopic observation revealed that the pigment had considerably penetrated into the inside of the roller. Also, under high temperature and high humidity, the charge amount is-
The image was extremely low at 5.4 μC / g, and fogging of the image on a white background was remarkably observed.

[Effects of the Invention] As described above, by using an appropriate amount of a quinacridone-based pigment and a xanthene-based dye, a clear magenta color is obtained, light fastness is improved, and dyeing on a silicone rubber roller is eliminated. It turns out that this invention is very useful industrially.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a color electrophotographic copying machine to which the color toner of the present invention is applied.

Claims (3)

(57) [Claims] 1. A magenta toner for forming a full-color image comprising at least a binder resin, a quinacridone-based organic pigment and a xanthene-based dye, and a metal chelate of an anthraquinone-based magenta dye or an alkyl salicylic acid as a negative charge control agent. The addition amount of the quinacridone-based organic pigment and the xanthene-based dye is 2 to 20 parts by weight based on 100 parts by weight of the binder resin, and the addition ratio of the quinacridone-based organic pigment to the xanthene-based dye is 100: 3 to 100. : 20, a negatively chargeable magenta toner for full-color image formation. 2. The negatively charged magenta toner for full-color image formation according to claim 1, wherein the binder resin is an unsaturated polyester resin. 3. The negatively charged magenta toner for full-color image formation according to claim 1, wherein the addition ratio of the quinacridone-based organic pigment to the xanthene-based dye is 100: 3 to 100: 90 / 5.1.