JPH0656507B2 - Electrophotographic toner - Google Patents

Description

TECHNICAL FIELD The present invention relates to a color toner for electrophotography, and more particularly to an electrophotographic toner containing a specific compound as a colorant.

BACKGROUND ART As means for developing an electrostatic latent image formed on an electrophotographic photoreceptor or electrostatic recording body, a method using a liquid developer (wet developing method) and a colorant in a binder resin are used. A method in which a dispersed toner or a one-component or two-component dry developer in which this toner is mixed with a solid carrier is used (dry development method) is generally adopted. Each of these methods has advantages and disadvantages, but at present, a dry developing method, especially a two-component developer, is widely used.

As the toner for two-component type developer, conventionally used is one obtained by adding a colorant (dye, pigment) to a binder resin, melt-kneading with a two-roll mill, and then finely pulverizing to a particle size of about 1 to 30 μm. ing. The toner has a particle size of 50 to 100 μm.
It is mixed with some carrier material and used to develop the electrostatic latent image.

By the way, in order for the toner and the carrier to be used for development, they must always cause a constant frictional charge in the copying machine, and the toner having a stable charge amount must be supplied to the electrostatic latent image. Therefore, (i) the binder resin and / or the colorant of the toner is appropriately selected so that the desired triboelectrification property can be obtained, or (ii) the charge control agent (the toner against the friction with the carrier Substance that controls the charging characteristics of
Is usually adopted.

However, the fact is that selection of the binder resin in (i) has not progressed as expected. For example, chlorinated paraffin, unsaturated polyester, etc. are used as a binder resin to control the toner to be negatively charged, and a specific polyester resin having a kind of cross-linking structure from the beginning (non-linear low melting point aromatic It is known to use a resin and a reaction product of a salicylic acid chelate), but it is difficult to obtain a desired molecular weight as a binder with these resins, and therefore, important thermal characteristics (heat during fixing) as a toner are not obtained. However, there is a problem in that a copy discharge error occurs due to copy wrapping around a heat roller, and a toner image on the paper is transferred to the roller surface, and offset development in which characters become unclear tends to occur.

Regarding the selection of the colorant in (i) above, benzidine yemey, etc. have been proposed or used in the example of yellow toner.These conventional ones have poor moisture resistance and show a decrease in chargeability due to water absorption at high humidity. In addition, since the color tone is also unsatisfactory (because of low saturation), the full-color color reproducibility due to the overlapping of the cyan toner, the magenta toner, and the yellow toner is poor.

On the other hand, as the charge control agent of the above (ii), for example, a nigrosine dye is known to give a positive charge to the toner,
Further, as a substance which imparts a negative charge to the toner, for example, a chromium-containing monoazo complex, a salicylic acid metal complex, a chromium-containing salicylic acid compound complex, a chloro-containing organic dye (copper phthalocyanine green, a chloro-monoazo dye), a metal-containing dye such as a phthalocyanine dye, nitrohumic acid. (Salt) is known. However, such conventional charge control agents do not have good charge controllability for a long period of time because they are mostly black substances or have poor compatibility or wettability with the binder resin, and are also sublimable. Most of them are unsuitable for color electrophotographic toners because they are materials or the like. Considering that the demand for obtaining multicolor copies from multicolor originals has been increasing in recent years, the use of conventional charge control agents is problematic. In addition, although the toner containing such a conventional charge control agent exhibits good developing characteristics in the initial stage, it has a short life and environmental stability (stability to temperature and humidity changes) is poor, causing a decrease in image density. However, it has the drawback of causing fog and dirt.

The conventional colorant and charge control agent are described in JP-B-48-259.
41, Japanese Patent Publication No. 48-26784, Japanese Patent Publication No. 49-20225, Japanese Patent Publication No. 50
-140137, JP-A-50-142037, JP-A-50-142038,
Japanese Patent Publication No. 46-43440, Japanese Publication No. 48-30899, Japanese Publication No. 49-46423
No. 49-26909, JP-A-49-51949, JP-A-49-1
No. 34303 and Japanese Patent Laid-Open No. 60-46566.

Aim The first object of the present invention is to provide an electrophotographic toner capable of obtaining a uniform image density and hardly causing peripheral effects and fog. A second object of the present invention is to provide a toner for a one-component or two-component dry developer which is suitable for high-speed development and which is excellent in durability and environmental stability. The third object of the present invention is not affected by changes in temperature and humidity,
It also provides a dry toner that does not cause the offset phenomenon.

The composition of the present invention is a color toner for electrophotography comprising a colorant and a binder resin as main components, wherein all or part of the colorant has the following structural formula (I). It is characterized by being Solvent Yellow 163 represented by.

By the way, when the present inventors adopt the specific compound represented by the general formula (I) as a colorant, the inconvenient phenomena such as the decrease in charging property and the poor color tone described above are not observed. The present invention has been completed and the present invention has been completed.

The amount of Solvent Yellow 163 (colorant) represented by the general formula (I) added to the toner is 100 parts by weight of the binder resin.
0.1 to 30 parts by weight, preferably 0.5 to 10 parts by weight is suitable.
It may be considered that a part of the solvent yellow 163 is mixed with a dye or pigment such as copper phthalocyanine, indanthrone or anthraquinone derivative (blue) to be a mixed color to obtain a green toner.

The present inventors have variously studied and studied the charge control of the toner as well as the colorant for dry toner. However, the metal salt of salicylic acid (particularly zinc salt) or the metal salt of salicylic acid derivative (particularly zinc salt) is a charge control agent. It was confirmed to be extremely effective as. Therefore, when the colorant represented by the general formula (I) is combined with such a charge control agent, a more desirable toner can be produced.

The metal salt of salicylic acid or a salicylic acid derivative can be represented by the following general formula (II).

(However, R ¹ , R ² and R ³ are hydrogen or an alkyl group having 1 to 10 carbon atoms or an allyl group, but particularly hydrogen or 1 to 6 carbon atoms.
Alkyl group or allyl group of Where R ¹ , R ²
And R ³ may be the same or different at the same time.
Further, Me is any metal selected from zinc, nickel, cobalt, copper and chromium, but zinc is particularly desirable. ) Such metal salts represented by the general formula are CLARK, JLKao, H.
It can be easily synthesized by the method described in (1948) J. Amer. Chem. Soc. 70, 2151. For example, 2 in a solvent
A sodium salt of salicylic acid (including a sodium salt of a salicylic acid derivative) and 1 mol of zinc chloride are added and mixed, and the mixture is heated and stirred to obtain a zinc salt. This metal salt is a white-colored crystal and does not show coloring even when dispersed in a toner binder. Metal salts other than zinc salts can also be produced according to the above method. These metal salts may be used alone or in combination of two or more kinds.

The amount of the metal salt in the toner is 0.1 to 10 parts by weight, preferably 0.5 to 7 parts by weight, based on 100 parts by weight of the binder resin. In addition, the amount of the colorant in the toner depends on the binder resin.
The amount is 0.5 to 10 parts by weight, preferably 1 to 7 parts by weight, based on 100 parts by weight.

The toner of the present invention contains the colorant represented by the general formula (I) and the binder resin as essential components, and preferably the general formula (II).
It is made by adding a charge control agent represented by.

Further, as the binder resin used in the present invention, as well as the above-mentioned colorant, all the binder resins used so far as the binder resin for toner can be applied. Specifically, styrene such as polystyrene, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-butadiene copolymer Including resin, saturated polyester resin, unsaturated polyester resin, epoxy resin, phenol resin, maleic acid resin, coumarone resin,
Chlorinated paraffin, xylene resin, vinyl chloride resin,
Examples include polypropylene and polyethylene. It goes without saying that two or more kinds of these binder resins may be appropriately mixed and used. Of these, use of polystyrene, styrene resin, and epoxy resin is advantageous.

In the toner of the present invention, in addition to the above components, various plasticizers (dibutyl phthalate, dioctyl phthalate, etc.) and resistance adjusters (for adjusting the thermal properties, electrical properties, and physical properties of the toner as necessary) It is also possible to add auxiliaries such as soot oxide, lead oxide, antimony oxide).

Further, in the present invention, after the production of toner particles (5 to 20 μm), fine powder such as TiO ₂ , Al ₂ O ₃ and SiO ₂ is added to the toner particles and the surface of the toner particles is coated with these to improve the fluidity of the toner. It is also effective to improve the properties of the photoconductor and to prevent deterioration of the photoconductor by adding zinc stearate, phthalic acid and the like.

As described above, the toner of the present invention is preferably mixed with a carrier and used as a two-component developer, but it can be used as a touch-down type one-component developer, and in some cases, a magnetic material (magnetite powder) may be used. Etc.) can be added and dispersed to be used as a normal one-component toner.

As a carrier, a styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, acrylic acid ester is formed on the surface of a core material (iron powder, nickel powder, ferrite powder, glass beads, etc.) having a particle size of about 50 to 300 μm. A polymer, a methacrylic acid ester polymer, a silicone resin, a polyamide resin, an ionomer resin, a polyphenylene sulfide resin, or the like, or a mixture of these resins is used. In particular, when a specific metal salt (a compound such as a zinc salt of salicylic acid and / or a zinc salt of a salicylic acid derivative) is added to the toner, a more desirable and stable negative charge is given to the metal salt. From the above, it is advantageous to use, as the coating resin for the carrier, a silicone resin or a silicone resin having conductive fine powder dispersed therein.

Next, examples and comparative examples will be shown. All parts here are parts by weight.

Example 1 100 parts of styrene-n-butyl methacrylate copolymer, 5 parts of pigment (Neo Sapon Yellow 073 manufactured by BASF) are melt-kneaded with a two-roll mill, cooled, and then average particle diameter is measured using a jet mill and a zigzag classifier. 11 μm toner was prepared. 5 parts of this toner TEFV200-
A developer was made by mixing with 95 parts of 300 carriers. The charge amount of the obtained developer was -15 μc / g. Next, this developer was placed in an electrophotographic copying machine (FT-6600, manufactured by Ricoh Co., Ltd.), and 50,000 continuous copies were made at room temperature and normal humidity (20 ° C. 65% RH). The charge amount rose to −18 μc / g. However, good copies were continuously obtained.

When 10,000 copies were continuously made in an environment of 30 ° C. and 90% RH, a good copy was obtained with a charge amount of −15 μc / g.

Comparative Example Styrene-n-butyl methacrylate copolymer 100 parts Lionol Yellow FGN-T (Benzidine Yellow manufactured by Toyo Ink Co., Ltd.) 5 parts A toner and a toner were prepared in the same manner as in Example 1 except that the resin and the colorant were changed to those described above. A developer was created. The charge amount of the obtained developer was −11 μc / g.

Further, when continuous copying was performed in an environment of 30 ° C. and 90% RH in the same manner as in Example 1, the amount of electrification decreased to −5 μc / g at the stage of humidity adjustment, and an unclear yellow copy with a soiled background was obtained. . After 2000 sheets were continuously copied, the charge amount further decreased to −2 μc / g and the copy quality deteriorated.

Example 2 Unsaturated polyester resin (Atlac382A manufactured by Kao Atlas Co., Ltd.) 100 parts Copper atalocyanine blue (Rionogen Blue MG-5 manufactured by Toyo Ink Co., Ltd.) 3 parts Solvent Yellow 163 (Neozapon Yellow 073 manufactured by BASF) 5 parts A green toner and a developer were prepared in the same manner as in Example 1 except that the resin and colorant were changed to those described above. The resulting developer had a charge amount of -20 μc / g.

In addition, this developer is applied to an electrophotographic copying machine (FT-manufactured by Ricoh Co., Ltd.
6400) and 100,000 copies were continuously copied, the charge amount after copying 100,000 copies was stable at -18 μc / g, and a good green image was obtained.

Example 3 Unsaturated polyester resin (Atlac382A manufactured by Kao Atlas Co., Ltd.) 100 parts Neozapon Yellow 073 (manufactured by BASF Co.) 5 parts Yellow toner similar to Example 1 except that the resin and the colorant are replaced by those described above. , A developer was created. The resulting developer had a charge amount of -15 μc / g.

When this developer-cyan and magenta were used as separate developers-is placed in a color electronic copying machine (Color 5000 manufactured by Ricoh Co., Ltd.) and an image is produced, a full-color image with good color tone reproducibility is obtained. Further, good images were obtained even after continuous copying of 10,000 sheets in an environment of 30 ° C. and 90% RH.

As is clear from the description of Examples, the use of dry toner using Solvent Yellow 163 as a colorant
By adding a small amount of colorant, a large number of highly colored and clear images can be obtained without being affected by changes in temperature and humidity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-55-166654 (JP, A) JP-A-61-112160 (JP, A) US Patent 4051077 (US, A)

Claims (1)

[Claims] 1. The following structural formula (I) An electrophotographic toner containing Solvent Yellow 163 represented by: