JPS62166360A - Blue toner for electrophotography - Google Patents

Abstract

PURPOSE:To form a blue toner for electrophotography generating almost no ambient effect nor fog, obtg. a uniform picture image density by using a specified compd. as colorant. CONSTITUTION:A compd. expressed by the formula (I) is used as colorant, wherein R' is H atom, alkyl group, phenyl group, substituted phenyl group, or alkoxyalkyl group. The formula (I-1) shows a specified example for the anthraquinone deriv. expressed by the formula (I). The amt. of the colorant to be added to the toner is 0.1-30, pref. 0.5-10pts.wt. per 100pts.wt. binder resin. If the amt. is less, the effect as blue colorant is insufficient. If the amt. is more than the range described above, undesirable result is obtd. because of inferior fixing characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color toner for electrophotography, and more particularly to a blue toner for electrophotography containing a specific compound as a colorant.

Conventionally, methods for developing electrostatic latent images formed on electrophotographic photoreceptors or electrostatic recording materials include a method using a liquid developer (wet development method) and a method using a colorant in a binder resin. A method (dry development method) using a toner in which the toner is dispersed or a one-component type or two-component type dry developer in which the toner is mixed with a solid carrier is generally adopted. Each of these methods has its own advantages and disadvantages, but at present, dry development methods, particularly two-component developers, are often used.

Toner for two-component developers has traditionally been obtained by adding colorants (dyes, pigments) to a binder resin, melting and kneading the mixture in a two-roll mill, etc., and then finely pulverizing the mixture to particles with a diameter of approximately 1 to 30 μm. ing. Such toner has a particle size of 50 to 100.
It is mixed with a carrier material (carrier) of about μm size and used for developing electrostatic latent images.

Incidentally, in order for the toner and carrier to be used for development, the toner must be supplied to the electrostatic latent image in a copying machine so that the toner does not always generate a constant amount of triboelectric charge and has a stable charge amount. Therefore, in order to obtain the desired triboelectrification property, (i) the binder resin and/or colorant of the toner should be appropriately selected, or (n) a charge control agent (the toner should be Usually, measures such as adding a substance (a substance that controls the charging characteristics of the toner) to the toner are taken.

However, the reality is that the selection of the binder resin in (i) above has not yet progressed as expected. For example, in order to control the toner to be negatively charged, chlorinated paraffin, unsaturated polyester, etc. are used as a binder resin, and specific polyester resins (non-linear, low-melting-point aromatic resins) that have a type of crosslinked structure from the beginning Although it is known that resins (such as reaction products of resins and salicylic acid chelates) are used, it is difficult to obtain the desired molecular weight as a binder with these resins. There are disadvantages such as copy ejection errors due to copy wrapping around the heat roller, and offset phenomenon in which the toner image on the paper transfers to the roller surface and the characters become unclear.

Regarding the selection of the colorant in (i) above, although the toner for liquid developer is an example, there are many types of dyes such as anthraquinone derivatives (those with long-chain alkylphenyl groups, long-chain alkylamino groups, etc. introduced), lake-formed dyes, etc. Alternatively, those made chargeable, those obtained by reacting with a surfactant, and those obtained by introducing an anthraquinone group into an acidic group-containing water-soluble dye have been proposed. However, the reality is that the addition of dyes such as these anthraquinone derivatives rarely exhibits good effects in the production of dry toners, particularly toners for two-component developers.

On the other hand, as the charge control agent (i), for example, nigrosine dyes are known as agents that impart a positive charge to the toner, and as agents that impart a negative charge to the toner, for example, chromium-containing monoazo complexes, chromium-containing salicylic acid compound complexes, Known examples include chlorine-containing organic dyes (copper phthalocyanine green and chlorine-containing monoazo dyes), metal-containing dyes such as phthalocyanine dyes, nitrofumic acids (salts), and anthraquinonediamine derivatives. But.

These conventional charge control agents are hexagonal black substances, have poor compatibility or wettability with the binder resin, and are sublimable, so they do not have good charge control properties over a long period of time. Most of them are unsuitable for color electrophotographic toners due to their presence. The use of conventional charge control agents is problematic in view of the increasing demand in recent years to obtain multicolor copies from multicolor originals. In addition, although toners containing conventional charge control agents exhibit good development characteristics initially, they have a short lifespan and poor environmental stability (degree of stability against changes in temperature and humidity), resulting in a decrease in image density. , it has drawbacks such as fogging and background smearing.

Note that the conventional coloring agent and charge control agent described above are
No. 25941, Special Publication No. 1977-26784, Special Publication No. 1977
-20225, JP 50-140137, JP 50-142037, JP 50-142038,
Special Publication No. 46-43440, Special Publication No. 48-30899, Special Publication No. 46423-1973, Special Publication No. 49-26909
No., JP-A-49-51949, JP-A-49-1343
This method is disclosed in publications such as No. 03 and Japanese Patent Publication No. 57-42860.

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

Structure The present invention provides a color toner for electrophotography containing a colorant and a binder resin as main components, wherein the colorant is represented by the following general formula (
I) R1 is a hydrogen atom, an alkyl group, a phenyl group, a substituted phenyl group, or an alkoxyalkyl group.

In addition to phthalocyanine-based dyes and pigments, triphenylmethane-based and indanthrone-based dyes and pigments are known as blue coloring agents.

When these are used as toner colorants, toner filming on the photoconductor is likely to occur, and when development is performed for a long time, stains on the background image become noticeable. Inconvenient phenomena such as variations in image density due to the use environment (changes in temperature and humidity) have often been observed, but the present inventors have developed a blue-colored compound using the specific compound represented by the general formula (I). It was confirmed that such an inconvenient phenomenon would not be observed if it was employed as a coloring agent, leading to the completion of the present invention.

Some specific examples of the anthraquinone derivative represented by the general formula (I) used as a colorant in the present invention are as follows.

(Nα1) (Nα2) (Nα3) υ N1-1. II These colorants may be used alone or in combination of two or more. The amount of the colorant added to the toner is 0.1 to 30 parts by weight, preferably 0.5 to 10 parts by weight, per 100 parts by weight of the binder resin.

If the amount added is less than this, the coloring effect as a blue color will be poor, and if it is more than this, the fixing property will be poor, which is undesirable. Through various studies and examinations, we have confirmed that metal salts of salicylic acid (especially zinc salts and chromium salts) or metal salts of salicylic acid derivatives (especially zinc salts and chromium salts) are extremely effective as charge control agents. Therefore.

A more desirable 1-ner can be produced by combining the colorant represented by the general formula (I) with such a charge control agent.

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

(However, R2, R1 and R4 are hydrogen or have 1 to 10 carbon atoms.
is an alkyl group or an allyl group, and hydrogen or an alkyl group having 1 to 6 carbon atoms or an allyl group are particularly preferred. Here, R2, R3 and R4 may be the same or different at the same time. Me is any metal selected from zinc, nickel, cobalt, copper and chromium, with zinc and chromium being particularly preferred. ) The metal salt represented by this general formula is CLARK.

J.L., Kao, 11. (I948) J, Amer,
It can be easily synthesized by the method described in Che++, Soc, 70,2151. For example, a zinc salt can be obtained by adding 2 moles of sodium salicylic acid salt (including sodium salts of salicylic acid derivatives) and 1 mole of zinc chloride to a solvent, mixing them, heating and stirring. This metal salt is a white crystal and does not show any 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.

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

The toner of the present invention preferably contains the colorant represented by the general formula (I) and the binder resin as essential components.

Alternatively, a charge control agent represented by the above general formula (U) may be added.

The coloring agents used in the present invention are limited to those represented by general formula (I), but it is possible to add some coloring agents of a similar color (blue).

Further, as for the binder resin used in the present invention, all of the binder resins that have been used hitherto as binder resins for toners can be used as well as the above-mentioned colorants. Specifically, polystyrene, styrene-acrylic acid copolymer, and styrene-methacrylic acid copolymer.

Including styrene resins such as styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, and styrene-butadiene copolymer, saturated polyester resin, unsaturated polyester resin, epoxy resin, phenolic resin, maleic acid resin , coumarone resin, chlorinated paraphyte, xylene resin, vinyl chloride resin, polypropylene, polyethylene and the like.

It goes without saying that two or more of these binder resins may be appropriately mixed and used. Among these, it is advantageous to use polystyrene, styrene resin, and epoxy resin.

In addition to the above-mentioned components, the toner of the present invention contains various plasticizers (dibutyl phthalate, dioctyl phthalate, etc.), resistance adjusters ( It is also possible to add auxiliary agents such as tin oxide, lead oxide, antimony oxide, etc.).

Furthermore, in the present invention, after producing toner particles (5 to 20 μm), TxO2g Al! o3 e 5102
The fluidity of the toner can be improved by adding fine powder such as and coating the surface of the toner particles.
It is also effective to add zinc stearate, phthalic acid, etc. to prevent deterioration of the photoreceptor.

As described above, it is preferable that the toner of the present invention be mixed with a carrier and used as a two-component developer, but of course it can also be used as a one-component developer using a touchdown method. etc.) can be added and dispersed and used as an ordinary one-component toner.

As a carrier, a core material with a particle size of about 50 to 300 μm (
iron powder, nickel powder, ferrite powder, glass peas, etc.)
on the surface of styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, acrylic ester polymer, methacrylic ester polymer, silicone resin, polyamide resin, ionomer resin, polyphenylene sulfide resin, etc., or a combination of these resins. A coated mixture 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 desired stable negative charge is imparted to the metal salt. From the above, it is advantageous to use a silicone resin or a silicone resin in which conductive fine powder is dispersed as the coating resin for the carrier.

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

Example 1 Styrene-n-butyl methacrylate copolymer 100 parts of the above Nα
10 parts of coloring agent 1 and 3 parts of zinc salt of salicylate are melt-kneaded 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 20 μm, which was used as a toner.

3.5 parts of this toner and about 1 part of carrier (silicone resin)
100μ spherical ferrite powder coated to μm thickness) 100
These parts were mixed to prepare a developer.

Using this developer, a dry plain paper copier (FT manufactured by Ricoh Co., Ltd.)
-5050) under an environment of 10°C, 15% RH, 120°C, 60% RH, and 30°C, 90% RH, a blue toner image with no fogging or background stains was obtained, and even after 20,000 continuous copies, copies were obtained. No deterioration in quality was observed [image density (measured with a Macbeth densitometer, same hereinafter) was 1.41 at the initial stage of copying, and 1.39 after 20,000 copies]. Note that the charge amount of this toner (the developer is used to blow off only the toner using a blow-off device, and the charge amount is measured using a Keithley device; the same applies hereinafter) is 113 μC/g, 2
After copying 10,000 copies, it was 114 μc/g.

Furthermore, when toners and developers were prepared using chromium salicylate instead of the zinc salicylate and tested in the same manner, almost the same effects were observed.

Comparative Example 1 Toner and developer were prepared in the same manner as in Example 1 except that the colorant was changed to the following substance, but the following substance was dissolved during crosstalk, and the dispersibility with the resin was equivalent to that of the year. For this reason, it was observed that the color tone was not fine and fine, the density of the image was low, and background staining occurred.

That is, using this developer, a dry plain paper copying machine (FT-5050 manufactured by Ricoh Co., Ltd.) was used at 10°C, 15% RH, 120°C, 60% R.
When the development was carried out under the environment of
Background smear occurred on 0 copies (image densities at initial copying and after copying 20,000 copies were 1.35 and 1.05). Further, the charge amount of the toner was 112 μC/g at the beginning of copying, and 0.5 μC/g after copying 20,000 sheets.

Example 2 The resin was styrene-acrylic acid copolymer (S manufactured by Sanyo Chemical Co., Ltd.)
A developer was prepared in the same manner as in Example 1 except that BM-73) was used instead.

Using this developer, a dry plain paper copier (FT manufactured by Ricoh Co., Ltd.)
-5050) under an environment of 10°C, 15% RH, 120°C, 60% RH, and 30°C, 90% RH, a blue toner image without background stains was obtained.

No deterioration in copy quality was observed even after continuous copying of 20,000 sheets.

Example 3 Example 1 except that the colorant was replaced with the Nα2 one.
A developer was prepared in the same manner.

Using this developer, a dry type electronic copying machine (FT-5 manufactured by Ricoh Co., Ltd.)
050) at lO ℃ 15% RH, 20 ℃ 60% RH and 3
When development was performed in an environment of 0° C. and 90% RH, a blue toner image without background stains was obtained. No deterioration in copy quality was observed even after continuous copying of 20,000 sheets.

The image density after initial copying and after 20,000 copies is 1.
40 and 1.41, and the charge amount of this toner is -15 μc/g and -1 at the initial stage of copying and after copying 20,000 sheets.
It was 4μc/g.

Example 4 A developer was prepared in the same manner as in Example 1 except that the colorant was changed to the Nα3 colorant.

Using this developer, a dry type electronic copying machine (FT-5 manufactured by Ricoh Co., Ltd.)
050) at lO ℃ 15% RH 120 ℃ 60% RH and 3
When development was performed in an environment of 0° C. and 90% RH, a blue toner image without background stains was obtained. Further, no deterioration in copy quality was observed even after 20,000 copies were made continuously (the image density was 1.40 at the initial stage of copying and 1.42 after 20,000 copies). The charge amount of this toner is 116 μc/g at the beginning of copying, and 11 μc/g after copying 20,000 sheets.
It was 5μc/g.

Comparative Example 2 Example 1 except that the colorant was replaced with a phthalocyanine blue pigment (Phthalocyanine Blue KL manufactured by Toyo Ink Co., Ltd.)
When a developer was prepared in the same manner as above and the same development was carried out, a blue-toned image was obtained, but background staining occurred after 7000 copies were made. The image density at the initial stage of copying and after 20,000 copies is 1.35 and 1.01, and the charge amount of this toner is -18 μc/g and -7 μc/g at the initial stage of copying and after 20,000 copies. Met.

As is clear from the description of the Examples, by using a dry toner with a specific colorant represented by the general formula (I) according to the present invention, high performance can be achieved with the addition of a small amount of colorant. A large number of colored and clear blue images can be obtained without being affected by changes in temperature and humidity.

Claims (1)

[Scope of Claims] 1. A color toner for electrophotography containing a colorant and a binder resin as main components, characterized in that the colorant is a compound represented by the following general formula (I). blue toner. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (However, R^1 is a hydrogen atom, an alkyl group, a phenyl group, a substituted phenyl group, or an alkoxyalkyl group.)