JPS63294571A - Photoconductive toner - Google Patents

Abstract

PURPOSE:To obtain excellent photosensitivity and fixability by incorporating a specific disazo pigment into particles essentially consisting of a thermoplastic resin. CONSTITUTION:The disazo pigment expressed by the formula I is incorporated into the particles essentially consisting of the thermoplastic resin. In the formula I, R1 denotes a hydrogen atom, halogen atom, alkyl group, alkoxy group, cyano group or nitro group; Y1 denotes a phenylene group or naphthylene group; n denotes 1 or 2 integer. A is expressed by the formula II. In the formula II, R2 denotes hydrogen, an alkyl group and aryl group which respectively may have a substituent; R3 denotes a hydrocarbon ring group, heterocyclic group, etc., which respectively may have a substituent. The photoconductive toner having the good photosensitivity and excellent dispersibility and thermal stability is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to toners, particularly photoconductive toners, for use in electrophotography.

2. Description of the Related Art Electrophotographic image forming methods are widely known. The usual method is to charge the entire surface of the photoreceptor by corona discharge, and then to form an electrostatic latent image by irradiating the photoreceptor with imagewise light. At this time, the exposed portion of the photoreceptor becomes conductive and the charge disappears, and the unexposed portion remains as an electrostatic latent image. When toner of opposite polarity is brought close to this electrostatic latent image, the toner is electrostatically attracted and the latent image is visualized.

In one type of xerography, the image is transferred to plain paper and fixed, while in the electrofax method, it is directly fixed on a photoreceptor. The problem with these methods is that these steps are complicated, making the electrophotographic copying apparatus complicated and expensive. Furthermore, since the copying system is constituted by independent members such as the photoreceptor and the toner powder, that is, the developer, the performance of one of the two members may deteriorate, so for example,
It is difficult to obtain high-quality copies due to optical fatigue of the photoreceptor or deterioration of the charging characteristics of the developer. There were problems such as maintenance became difficult.

In recent years, in order to solve these problems, a copying process has been proposed that does not use a photoreceptor and uses a photoconductive toner in which a developer is imparted with photoconductivity.

This method is a method in which the toner itself has the function of forming an electrostatic latent image, and since it does not require a photoreceptor, it has the advantage of simplifying electrophotographic copying equipment and lowering manufacturing costs.It also has the advantage of being able to produce full-color images in one shot. Research and development is being actively conducted on methods that can form images (for example, Japanese Patent Publication No. 56-28259, Japanese Patent Application Laid-Open No. 61-230154).
to 61-230158, etc.).

Electrophotography using photoconductive toner includes the Sugarman method (US Pat. No. 2,758,939), its modified form includes a combination method of photoconductive toner and corona discharge, and an electrophoresis method.

In order to realize the electrophotographic process described above, the development of photoconductive toner is the key, but such toner must have both functions as a developer and photoconductivity. Due to these difficulties, the photosensitivity in particular is far from a practical level, and it has not yet been put into practical use.

In Japanese Patent Publication No. 56-28259, it has been put to practical use as a photoconductive toner for marking. This toner uses zinc oxide as a photoconductive material with rose bengal as a sensitizer. However, the particle size of the toner is approximately 100 μm.
To a large extent, when considered as a toner for copiers, there is a problem in image quality, and it is not suitable for copiers because it uses a spray solution containing a solvent.

JP-A-61-230154 to JP-A-61-230158 disclose photoconductive toners, but the photoconductive substances are completely different.

Problems to be Solved by the Invention Since photoconductive toners have particularly poor photosensitivity and lack practicality, improvements are desired.

In view of such circumstances, it is an object of the present invention to provide a photoconductive toner with excellent photosensitivity and fixing properties.

Furthermore, the present invention provides a photoconductive toner containing a photoconductive material that is thermally stable, has good dispersibility, and in which the toner powder layer sufficiently retains the required functionality. be.

Means for solving the problem, that is, the present invention provides a photoconductive toner characterized by containing a disazo pigment represented by the following general formula (11) in particles mainly composed of a thermoplastic resin; In the formula, R1 is a hydrogen atom, a halogen atom, an alkyl group,
represents an alkoxy group, a reano group or a nitro group; y represents a phenylene group or a naphthylene group; n is an integer of 1 or 2; A represents the general formula (II) (wherein R2 is hydrogen, each having a substituent represents an alkyl group, aryl group, or heterocyclic group that may have a substituent; and represents a hydrocarbon cyclic group, a heterocyclic group, or a formula CDI which may each have a substituent. -N = C(III) ( In the formula, R4 represents hydrogen or a hydrocarbon cyclic group or a heterocyclic group, each of which may have a substituent, and R represents an alkyl group or aryl group, each of which may have a substituent, R4, R@ may be combined to form a ring): Z is fused with a benzene ring to represent a fused polycyclic hydrocarbon ring or a fused heterocycle, and a substituent is general formula (IV) (in the formula, λ represents a hydrocarbon group or a heterocyclic group which may have a substituent); general formula [v] (in the formula, X is a substituent (indicates a divalent group of an aromatic hydrocarbon or a divalent heterocyclic group which may have the following); or general formula [■] (representing a ring group)].

Some of the disazo pigments represented by the general formula [I] are disclosed as pigments for photoreceptors in JP-A-60-147743, but application to photoconductive toners is not described.

The present invention utilizes the disazo pigment represented by the general formula [■] as a photoconductive substance in a photoconductive toner, or by utilizing only the excellent charge generation ability of the disazo pigment of the present invention. When used in the charge generation layer of a functionally separated photoconductive toner, it exhibits excellent electrophotographic properties such as charge retention ability, sensitivity, and residual potential, and exhibits stable properties even when used repeatedly. The resulting photoconductive toner can be prepared.

Particularly good are those using the general formula (n]cV) as a coupler.

The compound represented by the general formula [■] of the present invention can be easily synthesized by a conventional method.

That is, the dinitro compound represented by the general formula [■] R1 is reduced with a reducing agent such as zinc-calcium chloride or tin chloride-hydrochloric acid to obtain the diamino compound represented by the general formula [■].

k.

A diamino compound is tetrazotized using sodium nitrite-hydrochloric acid, and the general formula [■], [1■] is obtained in the presence of an alkali.
～[[[[[]] is coupled with an appropriate force/amplifier component, or a diamino compound is tetrazotized,
It can then be synthesized by adding an acid such as IIBF+ and isolating it in the form of a salt, followed by a coupling reaction.

Specific examples of the coupler component Y used in the present invention include, but are not limited to, the following.

(The following is a blank space) 43, 0" (2pN C-COOC2H5 C-C00C2HIS 46・HC,CriNlfs An example of the structure of a photoconductive toner containing the disazo pigment of the present invention is schematically shown in FIGS. 1 and 2. Shown below.

Figure 1 shows a dispersed photoconductive toner (hereinafter referred to as "dispersed photoconductive toner") in which a disazo pigment (1) is dispersed together with a charge transport material (2) in a thermoplastic resin (3). show. The disazo pigment of the present invention acts as a photoconductive substance, and when it absorbs light, it generates a charge with extremely high efficiency, and the generated charge can be transported using the disazo pigment f1) as a medium, but the charge transport substance (2) ) is more effective when transported as a medium.

Figure 2 shows a coated photoconductive toner (hereinafter referred to as "coated photoconductive toner") in which a thermoplastic resin (3) in which a disazo pigment is dispersed is coated around a core material (4) containing a charge transport material. conductive toner). A coated photoconductive toner can improve light transmittance, and even when a single toner layer is formed into multiple layers, it is very advantageous in terms of photosensitivity.

The dispersed photoconductive toner can be produced by applying a known method. For example, fine particles of a disazo pigment may be dispersed in a thermoplastic resin solution, or a solution containing a charge transport substance and a thermoplastic resin solution, and the spray-drying method may be used to produce the dispersion, or a solvent-free heat kneading method may be used. You can do it (1 to 30, not particularly limited)
μm, preferably 5-25 μm1, more preferably 8-2
Adjust the particle size to 0 μm. If it is smaller than 1 .mu.m, the fluidity, development characteristics, etc. when formed into a toner will be poor, and the photosensitivity will also be significantly lowered. If it is larger than 30 μm, the final image, especially the resolution, will be poor. At this time, the disazo pigment is contained in an amount of 1 to 9 Qwt%, preferably 5 to 50W%. If it is less than 1 wt%, photosensitivity and coloring power will be insufficient. When the amount is more than 90W%, the binding property with the resin becomes poor and granulation becomes difficult. Furthermore, when the toner has multiple layers, light does not reach the lower layers, resulting in problems such as poor photosensitivity and increased residual potential. Note that a conductive substance may be added as necessary to suppress the increase in residual potential. If the amount of conductive material is large, problems such as an increase in dark capital and poor charging properties will occur.
The following are desirable.

Thermoplastic resins include polyethylene resin, acrylic resin, methacrylic resin, polyester resin, polyamide resin, polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyvinyl chloride,
Ethylene-vinyl acetate copolymer, styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-butadiene copolymer, styrene-vinylidene chloride copolymer, styrene-vinyl chloride co-electromodified rosin, Polyethylene wax, polycarbonate resin, etc. can be used alone or in combination.

In addition, when the photoconductive toner of the present invention is used particularly as a toner for pressure fixing, the thermoplastic resin may include polyolefins (low molecular weight polyethylene, low molecular weight polypropylene, polyethylene oxide, polytetrafluoroethylene, etc.),
Epoxy resin, polyester resin (oxidation 10 or less), styrene-butadiene copolymer (monomer ratio 5 to 30:9)
5-70), olefin copolymers (ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers,
Ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, (ionomer resin), polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer , maleic acid-modified phenol resin, phenol-modified terpene resin, etc. can also be used.

As charge transport substances, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidacilone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, pyrazoline derivatives, oxacylone derivatives,
benzothiazole derivatives, benzimidazole derivatives,
Quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, 2.4.7-1 linitrofluorenone, 2,4 Examples thereof include 5.7-titranitrofluorenone and 2.7-cynitrofluorenone. These charge transport materials can be used alone or in combination.

In the case of a coating type photoconductive toner, it can be obtained by further forming a layer containing a disazo pigment on the core material. As the binder resin, the same thermoplastic resin as described above can be used. For example, a layer containing a disazo pigment is coated on the core material by a spray drying method, or a thermoplastic resin monomer is used. However, methods such as emulsion polymerization or suspension polymerization to produce a multilayered polymer can be used.

The thickness of the coating layer is in the range of 0.1 to IO μm, preferably 0.1 to 2 μm, depending on the type and amount of each composition. Appropriate conditions are selected depending on characteristics such as image quality and printing density at the time of printing.

The amount of disazo pigment contained in the coating layer is 5 to 1%, preferably 20 to 80W%, more preferably 30 to 60W%, based on the total weight of the coating layer.
It is. If it is less than 5 wt%, the photosensitivity will generally be poor, and the print density as a final image may also be insufficient.

The particle size of the core substance is closely related to the particle size of the final photoconductive toner, and is therefore usually 1 to 30 μm, preferably 5 to 20 μm, regardless of the final image quality, especially the resolution.
belongs to. If it is smaller than 1 μm, the fluidity, development characteristics, and photosensitivity of the toner will be poor.
If it is larger than m, the final image quality, especially resolution and development characteristics, will be poor. Note that, although it is desirable that the nuclear core material is spherical, the shape is not limited.

The core substance may be the same as the thermoplastic resin described above, or may be a thermoplastic resin and/or a charge transport substance granulated by a thermal kneading-pulverization method. Alternatively, by emulsion polymerization or suspension polymerization of a mixture of thermoplastic binder resin monomer or prepolymer, charge transport substance, and other additives, or after dissolving the resin and charge transport substance in a solvent. It may also be obtained by a method such as granulation using a spray drying method.

The amount of the charge transport substance to be added is preferably an amount that does not precipitate when nuclear particles are prepared together with the thermoplastic resin, and it varies depending on the type of resin and charge transport substance, or whether it is added alone or in combination. is about 0.1 to 95 wt%, preferably 30 to 8 Qwt% based on the resin amount.
, more preferably 40 to □Qwt%. Q, l
If it is less than wt%, the carrier transport ability in the core substance will be poor, and if it is more than 95WL%, the charge transporting substance will usually precipitate in the resin, making granulation difficult.

Furthermore, the coating layer containing the disazo pigment may contain a charge transport substance to increase photosensitivity (Figure 3).
. In this case as well, the charge transport material may be the same as the charge transport material contained in the nuclear core particle, or a different charge transport material may be used. Of course, they may be added alone or in combination.

When a charge transport substance is present in the coating layer, the amount of the charge transport substance to be contained is 0 to 8 Qwt%, preferably 01 to 5 Qwt%, and more preferably 1 to 30W% based on the total amount of the coating layer. If the amount is more than 80 W%, the charge transport substance may precipitate, making it difficult to form a coating layer.

By including a charge transporting substance in the coating layer, not only does it become easier for photogenerated carriers to move in the coating layer, but also the movement of carriers between the nuclear core substance and the coating layer is facilitated, which improves photosensitivity. improvement is achieved.

A toner showing another aspect of the present invention includes a nuclear core material (
A photoconductive toner (Fig. 4) containing a charge transport substance (2) and a disazo pigment (1) in 4) and a disazo pigment (1) in a coating layer, both a core substance (4) and a coating layer. A photoconductive toner containing both a disazo pigment (1) and a charge transport substance (2) in the layer (Fig. 5), a disazo pigment (1) in the core substance (4), and a charge transport substance (2) in the coating layer. ) (Figure 6), a toner (Figure 7) containing a disazo pigment m in the core material (4), a disazo pigment (1) and a charge transport material (2) in the coating layer, a core material (Figure 7) (4) contains a charge transport substance (2) and a disazo pigment [11, a charge transport substance m in the coating layer]
(Fig. 8), toner containing disazo pigment (1) dispersed in thermoplastic resin (3) (Fig. 9), toner containing nothing in the core material (4), and toner containing nothing in the coating layer. A toner containing a disazo pigment fl+ (FIG. 10) or a toner containing nothing in the core substance (4) and a coating layer containing a disazo pigment (1) and a charge transport substance (2) (the first
Figure 1).

In order to take advantage of the coating-type photoconductive toner, which can obtain sufficient light transmittance and good photosensitivity, it is necessary to use a coating layer containing a core substance containing a charge transport substance and a disazo pigment. Photoconductive toners formed therein, ie, photoconductive toners of the embodiments shown in FIGS. 2-5, are preferred.

Furthermore, it is of course possible to use various disazo pigment sensitizing dyes or the like alone or in combination with the photoconductive substance shown in the present invention.

Coloring agents include known pigments or dyes, such as carbon black, nigrosine dye aniline blue, carfoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow,
Methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, oil black, azo oil black, rose bengal and mixtures thereof.

In addition, as a sensitizer, chloranil, tetracyanoethylene, 2,4.7-trinitro-9-alolenon, 5
, 6-dicyazbenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, electron-withdrawing sensitizers such as 3,5-dinitrobenzoic acid, methyl violet, rhodamine B, cyanine dyes, pyrylium salts, thiapyrylium salts, etc. It is also possible to use

In the photoconductive toner of the present invention, known additives may be used as appropriate within the range that does not impede the objects and effects of the present invention. As such additives, wax etc. can be added to improve fixing properties, and conductive substances such as fine metal oxide powder can be added to further improve photoconductivity.
In particular, it is possible to reduce the residual potential. Furthermore, in order to improve the properties as a toner, magnetic powder, colorant, charge control agent, fluidizing agent, etc. can be added as appropriate.

Particularly in the case of a coated photoconductive toner, a conductive substance such as wax or fine metal oxide powder can be added to the core material to improve fixing properties and conductivity. A charge control agent or a fluidizing agent can be added to the coating layer to improve charging properties and fluidity.

In addition, when using it as a toner containing a magnetic material, it is desirable to use a magnetic material that is chemically stable and can easily be obtained in the form of fine particles with a diameter of 1 μ or less. iron trioxide) is most preferred. Typical magnetic or oxidizable materials include cobalt, iron, nickel, metals such as aluminum, cobalt, copper, iron, lead, magnesium, nickel, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium. , manganese, selenium, titanium, tungsten, vanadium and mixtures thereof; metals including metal oxides such as aluminum oxide, iron oxide, copper oxide, nickel oxide, zinc oxide, titanium oxide, and magnesium oxide Compounds: refractory nitrides such as vanadium nitride and chromium nitride; carbides such as tungsten and silica carbide; ferrite and mixtures thereof, etc.
These ferromagnetic materials preferably have an average particle size of about 0.1 to 1 μm, and are contained in the toner in an amount of about 50 to 300 parts by weight based on 100 parts by weight of the resin component. 90 to 200 per 100 parts by weight of ingredients
Parts by weight.

When the purpose is a color magnetic toner, r-Fe, 0
．． A type of brown magnetic material or magnetic powder whose color is hidden by surface treatment is used.

Furthermore, the toner of the present invention can be used together with a fluidizing agent if necessary, and the fluidizing agent is preferably fine powder of hydrophobic silica, titanium oxide, aluminum oxide, etc., and the amount used is is 0.1~1wt for toner
% is preferred.

The photoconductive toner of the present invention can be used in a copying machine that does not have a photoreceptor. Therefore, the simplification of copying machines,
A reduction in manufacturing costs can be achieved. The photoconductive toner of the present invention can also be used in conventional copying machines.

The present invention will be explained below with reference to Examples, but the present invention is not limited to these examples.

(Leaving space below) Example 1 Styrene acrylic copolymer resin (SBM73, manufactured by Sanyo Chemical Industries, Ltd.) 100 parts dionazo azo component Disazo compound obtained from coupler component Y (1) 30 parts by weight P-diethylaminobenzaldehyde Diphenylhydrazone (DEH) (formula below) % Formula % After thoroughly mixing the above materials in a ball mill, 140°C
The mixture was kneaded on three rolls heated at .

The kneaded material was allowed to cool and then coarsely pulverized with a feather mill, pulverized with a pulverizer using a jet stream, and further classified with air to obtain a photoconductive toner (■) with an average particle size of 13 μm.

Example 2 Styrene-acrylic copolymer resin (softening point 135°C, glass transition point 58°C) 100 parts by weight Disazo component Coupler component Y (41) 30 parts by weight P-diethylamine,
Novenzaldehyde diphenylhydrazone (DEH)
A photoconductive toner (■) with an average particle size of 11.5 μm was obtained using 30 parts by weight of (imitation formula (Al)) 5 parts by weight of Viscoel 550P (manufactured by Sanyo Chemical Industries, Ltd.) in the same manner as in Example 1. .

Example 3 a) Production of core particles Styrene 70 parts by weight n-butyl methacrylate 30 parts by weight 2.2'-azobisin butyronitrile (polymerization initiator) 2 parts by weight Added as a dispersion medium to a uniform dispersion having the above composition. A composition of 400 parts by weight of 08W% methylcellulose aqueous solution and 0.1 part by weight of sodium laurate was added, and homomixing was performed at 5000 rpm for 10 minutes at room temperature. After this mixture was degassed and replaced with nitrogen, the temperature was raised to 70° C., and polymerization was carried out for 6 hours while stirring normally. This solution was poured into distilled water 21 and the operation of decantation was repeated three times, and then the particles were separated using a centrifuge and dried to obtain microparticles with an average particle size of io μm.

b) Production of photoconductive toner Thermoplastic resin: 70 parts by weight of styrene 20 parts by weight of n-butyl methacrylate 10 parts by weight of diethylamino methacrylate Copolymer (softening point: 135
℃, glass transition point 58℃) 10 parts by weight Disazo component Coupler component Y 50 parts by weight N-ethylcarbazole-3-aldehydemethylphenylhydrazone (MPH) (formula below) [
After homogeneously dispersing and stirring a substance of 1% formula % or more in toluene by high shear stirring, the nuclear core material obtained in the above nuclear particle production fat was added, and the surface was spray-dried using a spray drying method. A photoconductive toner (■) having an average particle size of 11 μm and a surface coating layer of 1.0 μm was obtained by coating.

After uniformly scattering the photoconductive toners ■ to ■ obtained in Evaluation Examples 1 to 3 on a brass substrate to form a thin toner layer, +
A 5 KV corona charge was applied to uniformly charge the toner layer, and then imagewise exposure was performed to form an electrostatic latent image on the toner layer. Next, a piece of plain paper was brought into close contact with the paper, and a corona charge of 15 KV with the opposite polarity to the charging electrode was applied from the paper side.
When the toner in the latent image area was transferred onto plain paper and further heat-fixed, a distinct dark purple image was obtained.

Effects of the Invention According to the present invention, a photoconductive toner having good photosensitivity, excellent dispersibility, and thermal stability can be obtained.

[Brief explanation of the drawing]

1 to 11 are schematic cross-sectional views showing one embodiment of the photoconductive toner of the present invention. (1)...Disazo pigment, (2)...Charge transport material, (3)...Thermoplastic resin, (4)...Nuclide core material. Applicant: Minolta Camera Co., Ltd. Figure 1 Figure 4 Figure 2 WIs diagram 3 Figure 3 Figure 7 Figure 2 Figure 119 Figure 1θ diagram Ml1 diagram

Claims (1)

[Scope of Claims] 1. A photoconductive toner characterized by containing a disazo pigment represented by the following general formula [I] in particles mainly composed of a thermoplastic resin; ▲Mathematical formula, chemical formula, There are tables, etc. ▼ [I] [In the formula, R_1 represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a cyano group, or a nitro group, and Y_
1 represents a phenylene group or a naphthylene group; n is an integer of 1 or 2; A is a general formula [II] ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ [II] (In the formula, R_2 is hydrogen, and each substituent is Indicates an alkyl group, aryl group, or heterocyclic group that may have a substituent; R_3 is a hydrocarbon ring group, a heterocyclic group, or a formula [III] that each may have a substituent ▲ Numerical formula, chemical formula, table, etc. ▼ [III] (In the formula, R_4 represents hydrogen or a hydrocarbon cyclic group or a heterocyclic group, each of which may have a substituent, and R_5 represents an alkyl group, each of which may have a substituent. represents an aryl group, and R_4 and R_5 may be combined to form a ring): Z represents a condensed polycyclic hydrocarbon ring or a condensed heterocycle by condensing with a benzene ring; , which may have a substituent); General formula [IV] ▲ Numerical formula, chemical formula, table, etc. ▼ [IV] (In the formula, R_6 is a hydrocarbon group or a heterocyclic group which may have a substituent. General formula [V] ▲ Numerical formulas, chemical formulas, tables, etc.▼ [V] (In the formula, X is a divalent aromatic hydrocarbon group or a heterocyclic group which may have a substituent. or general formula [VI] ▲Mathematical formulas, chemical formulas, tables, etc.▼[VI] (In the formula, R_7 represents an alkyl group, carbamoyl group, carboxyl group, or an ester thereof, and R_8 represents a substituent. Indicates a hydrocarbon cyclic group or a heterocyclic group that may have