JPH07319281A - Nonmagnetic one component developing method - Google Patents

Abstract

PURPOSE:To provide a developing method to obtain a uniform toner thin layer on a developing roller and to obtain enough developing property even when a nonmagnetic one-component developer of a small particle size is used. CONSTITUTION:This developing method is a non-contact type developing method using a nonmagnetic one-component developer. The nonmagnetic one-component developer consists of a nonmagnetic toner and a metal oxide powder deposited on the surface of the nonmagnetic toner. The nonmagnetic toner essentially consists of a binder resin, coloring agent and charge controlling agent. The charge controlling agent consists of a graft polymer (C1) having polyethylene main chains in which >50mol% of structural monomers are styrene and graft chains having the skeleton expressed by formula I, or consists of the graft polymer (C1) and polymer (C2) expressed by formula II. In formulae, R1 is a hydrocarbon group of 11-17 carbon number, R2 and R3 are hydrogen or hydrocarbon groups of 1-8 carbon number, R4 is an alkylene group of 1-12 carbon number, X<-> is anion,(m) is an integer 2-100, and (n) is an integer 2-100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type non-magnetic one-component developing method for developing an electrostatic latent image using a non-magnetic one-component developing agent.

[0002]

2. Description of the Related Art Generally, in electrophotography, an electric latent image is formed on a photosensitive drum, the latent image is then developed with toner, and the toner image is transferred to a transfer material such as paper as required. After that, it is fixed by means such as heating and pressurization to obtain a copy. Developers used in such an electrophotographic method include a two-component developer including a toner and a carrier, and a one-component developer having the functions of the toner and the carrier at the same time. The one-component developer is further classified into a magnetic one-component developer and a non-magnetic one-component developer. The two-component developer has excellent electrophotographic characteristics such as transferability, fixability, and environmental resistance, but requires a toner concentration sensor to control the mixing ratio of toner and carrier, and the life of the developer is short. However, there is a problem that the stirring mechanism of the developer becomes complicated. On the other hand, the magnetic one-component developer does not require the toner concentration sensor described above, and the developing device can be easily miniaturized. However, since it contains magnetic particles, it has a problem of poor fixability. From such a background, in order to achieve both compactness and simplification of the apparatus and fixing characteristics, a method of using a non-magnetic one-component developer as a one-component developer has been proposed and put into practical use in recent years.
The one-component developing method using a non-magnetic one-component developer includes contact-type non-magnetic one-component developing in which a developing roller carrying a non-magnetic one-component developer is brought into contact with a photosensitive drum having an electrostatic latent image for development. There is a method and a non-contact type non-magnetic one-component developing method in which a non-magnetic one-component developer on the developing roller is caused to fly by developing by providing a constant gap between the developing roller and the photosensitive drum. In the contact type non-magnetic one-component developing method, the non-magnetic one-component developer on the developing roller and the photosensitive drum having an electrostatic latent image come into contact with each other, so that the developability is good, but on the other hand, the non-magnetic one-component developing method is used. Since the component developer causes friction not only in the developing device but also with the photosensitive drum,
The mechanical load on the non-magnetic one-component developer is large. On the other hand, in the non-contact type non-magnetic one-component developing method, the developer is triboelectrically charged only by the layer regulating member, so that the mechanical load on the developer is small, but the non-contact type is not contacted. There is a problem that a sufficient image density cannot be obtained because the amount of the non-magnetic one-component developer (hereinafter, referred to as developability) that is generally flown from the developing roller to the photosensitive drum is smaller than that of the mold. .

In the non-contact type non-magnetic one-component developing method,
One of the means for improving the developability is to improve the fluidity by mixing and adhering hydrophobic silica or hydrophobic alumina as a fluidization improver on the surface of the non-magnetic one-component developer to improve the fluidity. It has been proposed to increase the supply of non-magnetic one-component developer to the image. However, such fluidization improvers generally have a strong positive or negative charge polarity. Therefore, when a large amount is mixed and adhered to the surface of the non-magnetic one-component developer, the non-magnetic one-component developer repels each other electrostatically and a uniform thin layer of the non-magnetic one-component developer is formed on the developing roller. There was a problem that it was difficult to obtain. On the contrary, due to the charging between the toner particles, toner particles having a charge opposite to the normal state are generated, which causes a problem of causing fog in the non-image portion. Further, in order to obtain a high-definition image, it is necessary to set the particle size of the non-magnetic one-component developer to a small value such as a volume average particle size of 10 μm or less. If the value is decreased, the amount of triboelectric charge increases and the relative increase in van der Waals force increases the adhesion of the non-magnetic one-component developer to the surface of the developing roller, which reduces the amount of flying to the photoconductor drum, There was a problem that the sex became worse.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances. Therefore, an object of the present invention is to obtain a uniform thin toner layer on a developing roller in a non-contact non-magnetic one-component developing method, and to obtain sufficient developability even with a non-magnetic one-component developer having a small particle size. It is to provide a developing method.

[0005]

SUMMARY OF THE INVENTION The present inventors have solved the problems of the non-contact type non-magnetic one-component developing method so that the non-magnetic one-component developer has a small particle size and can be developed well. As a result of diligent studies on the means for obtaining the property, as a non-magnetic one-component developer, a non-magnetic one-component developer containing a metal oxide powder in a positively chargeable non-magnetic toner containing a specific charge control agent was selected. It has been found that a non-magnetic one-component developing method which can obtain a uniform toner thin layer on the developing roller, which is the above-mentioned object, and has good developability even with a small particle size can be provided by using the present invention. It came to completion. That is, the present invention supplies a non-magnetic one-component developer to a developing roller,
A thin layer of the non-magnetic one-component developer is formed on the surface of the developing roller by a layer regulating member, and an electric charge is applied to the non-magnetic one-component developer to fly the non-magnetic one-component developer due to the potential difference between the photosensitive drum and the developing roller to form an electrostatic latent image. What is claimed is: 1. A non-contact type non-magnetic one-component developing method, comprising: developing a non-contact photosensitive drum to be held, then transferring to a transfer material, wherein the non-magnetic one-component developing agent comprises a binder resin, a colorant and a composition. A graft polymer (C1) comprising a polystyrene-based main chain in which 50 mol% or more of the monomers is styrene and a graft chain having a skeleton represented by the following general formula (1), or the graft polymer A positively chargeable non-magnetic toner mainly composed of a charge control agent composed of a polymer (C1) and a polymer (C2) represented by the following general formula (2) holds a metal oxide powder on its surface. Characterizing non Sex is a one-component developing method.

[Chemical 3] [Wherein R ₁ is a C _{11 to} C ₁₇ hydrocarbon group, R ₂ and R ₃ are each independently hydrogen or a C _{1 to} C ₈ hydrocarbon group, or R ₂ and R ₃ are They may be linked to each other to form an aromatic ring. R ₄ represents a C _{1 to} C ₁₂ alkylene group which may have an ether bond in the group, X ⁻ represents an anion, and m represents an integer of 2 to 100. ]

[Chemical 4] Wherein, R ₁ to R ₄ and X ^- is the same as that General formula (1), n represents an integer of 2 to 100. ]

The present invention will be described in detail below. Figure 1
FIG. 1 is a schematic configuration diagram of a developing device used in the non-contact type non-magnetic one-component developing method of the present invention. In the figure, 1 is a photosensitive drum,
Reference numeral 2 is a hopper, 3 is a non-magnetic one-component developer, 4 is a layer regulating member, 5 is a developing roller using an aluminum sleeve carrying a non-magnetic one-component developer, and 6 is a leakage preventing non-magnetic one-component developer. A toner scraping member, and 7 is a stirrer. In this developing device, an electrostatic latent image is formed on the photosensitive drum 1 by a known electrophotographic method.
A non-magnetic one-component developer 3 is accommodated in the hopper 2, and the non-magnetic one-component developer 3 is carried by the layer regulating member 4 on the developing roller 5 so as to have a constant layer thickness, and the layer is formed. Electric charges are applied by friction with the restriction member 4.
The developing roller 5 includes the photosensitive drum 1 and 50 μm to 200 μm.
It is installed through a gap of μm. The roller has
Apply a DC or AC voltage bias. The non-magnetic one-component developer carried on the developing roller 5 is conveyed by the rotation of the developing roller 5, and is fly to the surface of the photosensitive drum 1 by the potential difference between the photosensitive drum 1 having an electrostatic latent image and the developing roller 5. Then, the electrostatic latent image is visualized without contact. Then, the non-magnetic one-component developer on the surface of the photosensitive drum 1 is transferred to a transfer material (not shown). In the present invention, it is preferable to use a rubber blade as the layer regulating member. In the conventional non-magnetic one-component developing method, there is an example in which a metal blade is used as the layer regulating member, but when the metal blade is used, local toner fusion is likely to occur on the layer regulating member and the developing roller. It was confirmed that such local toner fusion is unlikely to occur when a rubber blade is used. The cause of this is not necessarily clear, but in the present invention, it is preferable to roughen the developing roller as described below, and when a roughened developing roller is used, the protrusions and layers of the developing roller surface are used. It is presumed that in the case of the metal blade, the local compressive force and the shearing force are stronger than the case of the rubber blade in contact with the regulating member. In the case of a metal blade, it is presumed that the toner particles are subjected to high stress when the toner passes through such a high stress portion, and therefore fusion is likely to occur. On the other hand, in the case of the rubber blade, the followability to the irregularities on the surface of the developing roller is good, and since the stress difference between the concave portion and the convex portion is smaller than that in the case of the metal blade, the stress on the toner is uniformized and melted. It is estimated that it is difficult to wear them. In the present invention, the developing roller has Rz of 0.5 to 15 μm and R
It is preferable that the surface is roughened to a maximum of 20 μm or less. R
When z is less than 0.5 μm, the toner layer is not formed to the extent necessary for development, and the amount of development tends to be insufficient. On the other hand, R
If z is larger than 15 μm, the toner may be clogged in the roughened concave portion, which is one of the factors that hinder the charging of the toner during continuous imaging, which is not preferable. It has been found that when the Rz of the surface of the developing roller in the present invention is in the range of 0.5 to 15 μm, the toner layer thickness is sufficiently thick, good developability can be obtained, and clogging of the toner hardly occurs. Even if Rz is in the range of 0.5 to 15 μm, Rma
If there is local unevenness such that x exceeds 20 μm, clogging of the toner is likely to occur at that portion, which is not preferable for the same reason as above. The surface roughening of the developing roller is measured according to JIS B0601. In the present invention, the gap between the developing roller and the photosensitive drum is preferably 50 μm to 200 μm. In particular, in the case of a flying method using a DC voltage, the narrower the voids, the better the developability, but if it is less than 50 μm, it is extremely difficult to control the mechanical precision in production, which is not preferable. On the other hand, if it is wider than 200 μm, it is difficult to obtain a sufficient electric field strength required for development, and the developability may be insufficient.

Next, the non-magnetic one-component developer constituting the present invention will be described in detail. The non-magnetic one-component developer is a binder resin,
Is it composed of a graft polymer (C1) having a polystyrene-based main chain in which 50 mol% or more of the colorant and the constituent monomers are styrene, and a graft chain having a skeleton represented by the general formula (1)? Or the graft polymer (C
1) and a polymer (C2) represented by the general formula (2) and a charge control agent as a main component. As the binder resin of the positively chargeable non-magnetic toner, for example, polystyrene, polyester, acrylic resin, styrene-acrylic copolymer, ethylene-vinyl chloride copolymer, polyamide, polyethylene, maleic acid resin, xylene resin,
Examples thereof include, but are not limited to, phenolic resins.

As the colorant, for example, black colorants such as carbon black, acetylene black, lamp black, channel black, aniline black, and the like,
Examples of chromatic colors include Farnal Blue, Permanent Blue, Nigrosine Blue, Phthalocyanine Cyan Color Pigment, Rose Bengal, Xanthene Magenta Color Dye, Quinacridone Magenta Color Pigment, Monoazo Red Pigment, and Disazo Yellow Pigment. However, the present invention is not limited to these. These colorants are appropriately mixed in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the binder resin. Next, the charge control agent used in the present invention will be described. Graft polymer (C1) constituting the charge control agent used in the present invention
Is obtained by introducing the graft chain represented by the general formula (1) into the functional group portion of the styrene resin having a functional group, and the polystyrene main chain is the functional group of the styrene resin having a functional group. The one without the part. Examples of the styrene resin having a functional group include a styrene resin having a halomethyl group and a styrene resin having an amino group. In the general formula (1), examples of the C _{11 to} C ₁₇ hydrocarbon group of R ₁ include an alkyl group, an alkenyl group and an alkylphenyl group. Further, hydrogen, an alkyl group, an aryl group, an aralkyl group and the like are mentioned as the hydrogen of R ₂ and R ₃ or the hydrocarbon group of C _{1 to} C ₈ . Examples of the aromatic ring in which R ₂ and R ₃ are connected to each other include a benzo group. Regarding the molecular weight of the graft polymer (C1), the number average degree of polymerization of the polystyrene main chain, that is, the number average degree of polymerization of the styrene resin is 5 to 500, and the number average degree of polymerization m of the graft chain is 2 to 100. . The charge control agent used in the present invention comprises the graft polymer (C1) or the graft polymer (C1) and the polymer (C2). The polymer (C2) is a homopolymer obtained by homopolymerizing a part of the graft chains of the graft polymer (C1) without binding to the main chain. The number average degree of polymerization n of the homopolymer is 2 to 100. The composition ratio of each component in the charge control agent is 25 to 100% of the graft polymer (C1) in terms of the weight ratio of the graft chain constituting the graft polymer (C1) and the weight ratio of the polymer (C2), Polymer (C2) is 0
75%. The charge control agent used in the present invention is desirably 1 to 20 parts by weight, preferably 2 to 15 parts by weight, based on 100 parts by weight of the binder resin. If it is less than 1 part by weight, a sufficient charge control function cannot be obtained, and problems such as fog and toner scattering may occur. On the other hand, if the amount exceeds 20 parts by weight, an appropriate triboelectric charge amount may be exceeded, and a sufficient image density may not be obtained. If desired, the positively chargeable non-magnetic toner may contain other components, for example, additives such as low molecular weight polypropylene, silicone oil, and thermoplastic silicone resin. Further, one or more charge control agents such as nigrosine dye and quaternary ammonium salt may be contained.
The positively chargeable non-magnetic toner preferably has a volume average particle size of 12 μm or less, preferably 3 to 10 μm. If the volume average particle size is less than 3 μm, sufficient fluidity may not be obtained. On the other hand, if it is larger than 10 μm, the reproducibility of pixels such as thin lines and characters may be deteriorated.
The positively chargeable non-magnetic toner is obtained by melting a binder resin, a colorant, a charge control agent and, if desired, other additives in a predetermined mixing ratio with a mixture of raw materials, which is an extruder, a Banbury mixer, or a mixer. It is obtained by melt-kneading with a shaft kneader or the like, then pulverizing and classifying. The specific charge control agent, which is a feature of the present invention, can be easily finely dispersed in the binder resin by the above-mentioned melt-kneading means. In particular, when polystyrene or a styrene-acrylic copolymer is used as the binder resin, the compatibility between the polystyrene main chain contained in the charge control agent and the binder resin is good, so It is preferable because uniform fine dispersion is possible.
As a means for obtaining the positively chargeable non-magnetic toner, it is also possible to obtain it by a polymerization method such as suspension or emulsion. Regarding the function and effect of the present invention, the positively chargeable non-magnetic toner obtained by the above-mentioned melt-kneading method is used. It is no different from toner. In the present invention, a toner whose frictional charge with the layer regulating member and the developing roller is positive is called a positively chargeable non-magnetic toner.

The metal oxide powder retained on the surface of the positively chargeable non-magnetic toner is composed of oxides of metal elements of Groups 2, 3 and 4 in the periodic table alone, or Any fine powder composed of the metal oxide compounded with another metal may be used. For example, MgO, Zn
_{O, Al 2 O 3, TiO} 2, SnO 2 and the like. In particular, in order to obtain the effect of the present invention, zinc oxide (ZnO) and alumina (Al ₂ O ₃ ) are preferable because they tend to have positive chargeability. The amount of the metal oxide powder added to the positively chargeable non-magnetic toner is 100 parts by weight of the positively chargeable non-magnetic toner.
0.1 to 5 parts by weight is desirable. If the amount is less than 0.1 parts by weight, the non-magnetic one-component developer particles or the non-magnetic one-component developer and the developing roller are strongly adhered to each other, and a practically sufficient image density may not be obtained. On the other hand, when the amount is more than 5 parts by weight, the triboelectric charge amount of the non-magnetic one-component developer is too low and it is difficult to form a good toner thin layer on the developing roller.
Toner scattering from the developing machine may increase. Also,
The metal oxide powder has a primary particle diameter of 0.01 to 0.5 μm.
Is desirable. If the primary particle size of the metal oxide powder is less than 0.01 μm, the ability to retain the positively chargeable non-magnetic toner may be poor, and if it exceeds 0.5 μm, the ability to uniformly retain the positively chargeable non-magnetic toner may be improved. Is good, but the holding power is likely to be weak, and it may be easy to peel and separate from the positively chargeable non-magnetic toner particles. In order to hold the metal oxide powder on the surface of the positively chargeable non-magnetic toner, a positively chargeable non-magnetic toner having a predetermined mixing ratio is used by using a mixer such as a Henschel mixer or a super mixer for powder. It can be performed by stirring a mixture of the metal oxide powder and the metal oxide powder. When a mixer such as a Henschel mixer or a super mixer is used, the mixing may be performed for a relatively short time under mild stirring conditions. Incidentally, to hold the metal oxide powder on the surface of the positively chargeable non-magnetic toner in the present invention means a state in which the metal oxide powder is electrostatically attached to the surface of the positively chargeable non-magnetic toner (sprayed). And a state in which the metal oxide powder is embedded (fixed state). In particular, all or part of the metal oxide powder is a positively chargeable non-magnetic toner as shown in FIG. It is preferable that the metal oxide powder 9 is not embedded in the surface of 8 and is electrostatically attached thereto. When held in the state as shown in FIG. 2, repulsion and aggregation due to the electrostatic force between the non-magnetic one-component developer particles are reduced, and a good toner thin layer can be formed on the developing roller. . A fluidity improver such as hydrophobic silica may be added at the same time as the metal oxide powder for adjusting fluidity. Also in this case, it is possible to use the same powder mixer as described above.

[0010]

In the non-contact developing method using the positive polarity non-magnetic one-component developer, the triboelectric charge amount of the positively charging non-magnetic toner used as the non-magnetic one-component developer is improved in order to improve the flight developing property. It is necessary to keep it low on the positive side. However, if the triboelectric charge amount is too low, problems such as fog and toner scattering tend to occur. Therefore, the triboelectrification amount of the non-magnetic one-component developer as a whole is low, and the triboelectrification amount of each non-magnetic one-component developer particle is similar, and the width of the triboelectrification amount distribution is narrow and sharp. There is a need to. The specific charge control agent used in the present invention is capable of extremely fine dispersion in the binder resin, can narrow the triboelectric charge amount distribution, and at the same time suppress it to a low triboelectric charge amount. Therefore, good developability can be obtained. Also,
To obtain a uniform thin toner layer on the developing roller, repulsion due to static electricity between non-magnetic one-component developer particles,
It is necessary to prevent aggregation due to triboelectric charging between non-magnetic one-component developer particles. By holding the metal oxide powder in the present invention on the surface of the positively chargeable non-magnetic toner, the repulsion and aggregation of the particles as described above are reduced, and a good toner thin layer can be formed on the developing roller. . In addition, since the metal oxide powder in the present invention has a relatively positive charging property, when it is held on the surface of the positively charging non-magnetic toner particles, it is difficult to generate toner particles of opposite polarity charging, and the above charge control agent is used. And the developability can be improved. Further, by holding the metal oxide powder on the surface of the positively chargeable non-magnetic toner, the contact distances between the non-magnetic one-component developer particles and between the particles and the developing roller are increased, and aggregation between the particles is prevented. This makes it possible to improve the developability. Further, when the toner particle size becomes smaller, the triboelectric charge amount on the developing roller becomes higher and the developability deteriorates. However, in the case of the present invention, by holding the metal oxide powder on the positively chargeable non-magnetic toner surface. Further, the triboelectric charge amount can be controlled within an appropriate range, and the developability becomes good.

[0011]

EXAMPLES The present invention will be described below based on examples. In the examples, “part” means “part by weight”. Example 1 794 parts of styrene, 160 parts of butyl acrylate and 46 parts of chloromethylstyrene were dissolved in toluene, and 30 parts of azobisisobutyronitrile was added as a polymerization initiator while controlling the polymerization temperature to the boiling point of toluene. Polymerize,
Then, the solvent was removed to obtain a styrene resin having halomethyl having a number average molecular weight of 6000 and a weight average molecular weight of 17,000. 128 parts of this styrene resin, 125 parts of heptadecylbenzimidazole, 68 parts of 1,4-dibromobutane and 18 parts of sodium carbonate were reacted in dimethylformamide at 80 ° C. for 2 hours and under reflux for 4 hours. Then, 5 parts of benzol chloride was added and the mixture was refluxed for 4 hours. After completion of the reaction, the reaction product was put into an aqueous solution in which 205 parts of p-toluenesulfonic acid was dissolved in 2000 parts of water while stirring with a homomixer. The precipitate is washed with water, filtered and dried,
A charge control agent containing a graft polymer (C1) having a graft chain of the following general formula was obtained.

[Chemical 5] Next, the raw materials were mixed in the following formulation, melt-kneaded and then pulverized and classified to obtain a positively chargeable non-magnetic toner having a volume average particle diameter of 7.5 μm. This positively chargeable non-magnetic toner 100
Zinc oxide (Mitsui Kinzoku Co., Ltd. product name: Pastran t
ypeII 2410 primary particle size 0.02 μm).
A non-magnetic one-component developer was obtained by adding 0 parts and stirring for 2 minutes with a Henschel mixer. -Styrene-acrylic copolymer resin 100 parts (Fujikura Chemical Co., Ltd. monomer styrene / butyl acrylate / n-butyl methacrylate = 78/18/4, Mn: 2.9 x 10 ⁴ , Mw: 32.8 x 1 0 ⁴ ) ・ Carbon black 10 parts (Cabot Co., Ltd. product name: BPL) ・ The above charge control agent 8 parts ・ Polypropylene wax 2 parts (Sanyo Chemical Co., Ltd. product name: Viscor 660P)

Example 2 For 100 parts of the positively chargeable non-magnetic toner obtained in Example 1, zinc oxide (trade name: Pastran type II manufactured by Mitsui Kinzoku Co., Ltd.) was used.
2410 1.0 part of primary particle diameter 0.02 μm and hydrophobic alumina (trade name: RFY- manufactured by Nippon Aerosil Co., Ltd.)
C) and 0.5 parts were added at the same time and mixed by the same mixing method as in Example 1 to obtain a non-magnetic one-component developer.

Example 3 Polyvinyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd., polymerization degree: about 200)
(0, saponification degree: about 80%) was prepared as an aqueous solution of 1% with respect to water and sodium sulfate with 3% with respect to water to prepare an aqueous medium. On the other hand, 2,2 'was added to the monomer composition consisting of 4000 g of styrene and 1000 g of butyl acrylate.
-Preparation of a mixed solution in which 15 g of azobisisobutyronitrile was dissolved, and 400 g of carbon black (trade name: # 40 manufactured by Mitsubishi Kasei Co., Ltd.) and 150 g of the charge control agent obtained in Example 1 were added to this mixed solution. An ultrasonic disperser was used to disperse the mixture for 30 minutes to prepare a dispersion liquid. Next, the above dispersion liquid is mixed with 10
A flow rate of 0 ml / min, the aqueous medium was fed to the granulator by separate routes at a flow rate of 400 ml / min for 10 minutes. The granulator used has a rotating part with a diameter of 50 mm.
The mixture of the dispersion and the aqueous medium was stirred under the condition of 00 rpm. Then, the mixed liquid that passed through the granulator was introduced into a polymerization tank while stirring at 300 rpm with a turbine-type stirring blade, and reacted for 8 hours. Then, the polymer particles were separated by a centrifugal dehydrator, further washed sufficiently with water and then dried to obtain a positively chargeable non-magnetic toner composed of the polymer particles. The volume average particle diameter of the positively chargeable non-magnetic toner was 6.5 μm. Next, 100 parts of the positively chargeable non-magnetic toner was mixed with zinc oxide (trade name: Pastran type II 2 manufactured by Mitsui Kinzoku Co., Ltd.
410 primary particle diameter 0.02 μm) and 1.0 part of hydrophobic alumina (product name: RFY-C manufactured by Nippon Aerosil Co., Ltd.)
And 0.5 parts were simultaneously added and mixed by the same mixing method as in Example 1 to obtain a non-magnetic one-component developer.

Comparative Example 1 The positively chargeable non-magnetic toner of Example 1 was used as it was as a non-magnetic one-component developer for comparison.

Comparative Example 2 A nonmagnetic one-component developer for comparison was prepared in the same manner except that the charge control agent of Example 1 was replaced with 2 parts of a nigrosine dye (trade name: Bontron N04 manufactured by Orient Chemical Industry Co., Ltd.). Obtained.

Comparative Example 3 A nonmagnetic one-component developer for comparison was obtained in the same manner as in Example 1 except that the charge control agent was omitted.

Using the non-magnetic one-component developer obtained by the above operation, a remodeled machine of a commercially available laser beam printer (trade name: L-880 manufactured by Kyocera Corp.) having the developing device of FIG. The voltage was changed to -100V and the surface potential of the photosensitive drum was changed to -900V for normal development. The layer regulating member was a rubber blade made of urethane, and the surface of the developing roller was roughened by a surface treatment by a sandblast method. Was 6 μm, Rmax was 17 μm, and the gap between the photoconductor drum and the developing roller was 120 μm), and a print test was performed. As a result, in each of the non-magnetic one-component developers of Examples 1 to 3, a uniform thin layer was formed on the developing roller. Further, when a solid image of the non-magnetic one-component developer transferred from the photosensitive drum onto the transfer paper is measured by a Macbeth reflection densitometer (trade name: RD-914 manufactured by Macbeth Co.), Example 1 shows 1.3.
5, good image densities of 1.39 in Example 2 and 1.34 in Example 3 were obtained, and a sufficient amount of non-magnetic one-component developer was jetted from the developing roller to the photosensitive drum. Backed up. On the other hand, Comparative Example 1 and Comparative Example 2
The non-magnetic one-component developer of No. 1 does not form a uniform thin layer on the developing roller and has a high triboelectric charge amount. When a solid image is measured with a Macbeth reflection densitometer, Comparative Example 1 shows 0.75, Comparative Example 1 2 was a low image density of 0.56, and it was confirmed that the non-magnetic one-component developer flies to the photosensitive drum in a small amount. Further, the non-magnetic one-component developer of Comparative Example 3 could not form a uniform thin layer on the developing roller,
Since the developer was scarcely ejected onto the transfer paper, the image density of the solid image could not be measured. This is because the charge control agent is not contained in the positively chargeable non-magnetic toner at all, the positively chargeable non-magnetic toner is not charged, and the adhesion force of the non-magnetic one-component developer to the developing sleeve is small. It is presumed that the formation of the thin layer on the developing sleeve became defective.

[0018]

As described above, the present invention uses a non-magnetic one-component developer in which a metal oxide powder is held on the surface of a positively chargeable non-magnetic toner containing a specific charge control agent as described above. A uniform thin toner layer can be obtained on the upper side, and good developability can be obtained even if the non-magnetic one-component developer has a small particle size.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a non-contact type non-magnetic one-component developing device for carrying out the present invention.

FIG. 2 is a schematic diagram showing a state of metal oxide powder held on the surface of a positively chargeable non-magnetic toner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Hopper 3 Non-magnetic one-component developer 4 Layer regulating member 5 Developing roller 6 Leak prevention and toner scraping member 7 Stirrer 8 Positively chargeable non-magnetic toner 9 Metal oxide powder

Claims (4)

[Claims] 1. A non-magnetic one-component developer is supplied to a developing roller, a thin layer of the non-magnetic one-component developer is formed on the surface of the developing roller by a layer regulating member, and an electric charge is applied to the developing roller and the photosensitive drum and the developing roller. A non-contact type non-magnetic one-component developing method in which the non-magnetic one-component developer is caused to fly by a potential difference between The non-magnetic one-component developer contains 50% of the binder resin, the colorant and the constituent monomers.
A polystyrene-based main chain in which styrene is at least mol%,
It is composed of a graft polymer (C1) having a graft chain having a skeleton represented by the following general formula (1), or the graft polymer (C1) and a polymer (C2) represented by the following general formula (2). A non-magnetic one-component developing method characterized in that a metal oxide powder is held on the surface of a positively chargeable non-magnetic toner mainly composed of a charge control agent. [Chemical 1] [Wherein R ₁ is a C _{11 to} C ₁₇ hydrocarbon group, R ₂ and R ₃ are each independently hydrogen or a C _{1 to} C ₈ hydrocarbon group, or R ₂ and R ₃ are They may be linked to each other to form an aromatic ring. R ₄ represents a C _{1 to} C ₁₂ alkylene group which may have an ether bond in the group, X ⁻ represents an anion, and m represents an integer of 2 to 100. ] [Chemical 2] Wherein, R ₁ to R ₄ and X ^- is the same as that General formula (1), n represents an integer of 2 to 100. ] 2. The non-magnetic one-component developing method according to claim 1, wherein the metal oxide powder is at least one selected from zinc oxide and alumina. 3. The layer regulating member is a rubber blade, the surface of the developing roller is roughened, and the gap between the photosensitive drum and the developing roller is 50 to 200 μm. Non-magnetic one-component developing method. 4. The non-magnetic one-component developing method according to claim 3, wherein the surface roughness of the developing roller is 0.5 to 15 μm in Rz and Rmax is 20 μm or less.