JP2843258B2 - Non-magnetic one-component development method - Google Patents

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 developer.

[0002]

2. Description of the Related Art In general, in electrophotography, an electric latent image is formed on a photosensitive drum, the latent image is developed with toner, and a toner image is transferred to a transfer material such as paper as necessary. Thereafter, fixing is performed by means such as heating and pressurization to obtain a copy. As a developer used in such an electrophotographic method, there are a two-component developer including a toner and a carrier, and a one-component developer having both functions of a toner and a carrier. One-component developers are further classified into magnetic one-component developers and non-magnetic one-component developers. The two-component developer has excellent electrophotographic properties such as transferability, fixability, and environmental resistance, but requires a toner concentration sensor to control the mixing ratio of toner and carrier, and has a short developer life. And a problem that the stirring mechanism of the developer becomes complicated. On the other hand, the magnetic one-component developer does not require the above-mentioned toner concentration sensor, and can easily reduce the size of the developing device, but has a problem that the fixing property is inferior because it contains magnetic particles. In view of such a background, a method using a non-magnetic one-component developer as a one-component developer has been proposed and put to practical use in order to achieve both the simplification of the apparatus and the fixing characteristics.
A one-component developing method using a non-magnetic one-component developer includes a contact-type non-magnetic one-component developing method 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 to perform development. And a non-contact type non-magnetic one-component developing method in which a certain gap gap is provided between the developing roller and the photosensitive drum, and the non-magnetic one-component developer on the developing roller is caused to fly to develop. 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 are in contact with each other, so that the developing property is good. Since the component developer causes friction not only in the developing device but also between the photosensitive drum,
The mechanical burden 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 frictionally charged only by the layer regulating member, so that the mechanical load on the developer is small. In general, the amount of non-magnetic one-component developer (hereinafter referred to as "developability") flying from the developing roller to the photosensitive drum is smaller than that of the mold, so that a sufficient image density cannot be obtained. .

In a non-contact 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 to the surface of the non-magnetic one-component developer to improve the electrostatic latent. 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 of non-magnetic one-component developer 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. Conversely, charging between toner particles generates toner particles having a charge opposite to that of normal toner, which also causes a problem of causing fog in a non-image portion. Further, in order to obtain a high-definition image, it is necessary to set the particle diameter of the non-magnetic one-component developer to, for example, a small volume average particle diameter of 10 μm or less. When the value is reduced, the amount of non-magnetic one-component developer attached to the developing roller surface becomes stronger due to an increase in the amount of triboelectric charge and a relative increase in the fan Des Waals force. There was a problem that the quality became worse.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional situation. Therefore, an object of the present invention is to obtain a uniform toner thin 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 diameter. To provide a developing method.

[0005]

Means for Solving the Problems The present inventors have solved the problem of the non-contact type non-magnetic one-component developing method so that even if the non-magnetic one-component developer has a small particle diameter, a satisfactory development can be achieved. As a result of intensive studies on the means for obtaining the property, as a non-magnetic one-component developer, a non-magnetic one-component developer holding a metal oxide powder in a positively chargeable non-magnetic toner containing a specific charge control agent was used. By using the same, a uniform thin toner layer can be obtained on the developing roller, which is the above object, and it has been found that a non-magnetic one-component developing method having good developability even with a small particle diameter can be provided. It was completed. That is, the present invention supplies a non-magnetic one-component developer to a developing roller,
The layer regulating member forms a thin layer of the non-magnetic one-component developer on the surface of the developing roller and gives an electric charge, and the non-magnetic one-component developer flies by a potential difference between the photosensitive drum and the developing roller to form an electrostatic latent image. A non-contact type non-magnetic one-component developing method in which a non-contact developing is performed on a photosensitive drum to be held in a non-contact manner, and then transfer is performed on a transfer material, wherein the non-magnetic one-component developing agent includes a binder resin, a colorant, and a composition. A graft polymer (C1) having a polystyrene-based main chain in which 50% by mole or more of the monomer is styrene and a graft chain having a skeleton represented by the following general formula (1), or The surface of a positively chargeable non-magnetic toner mainly composed of a charge control agent comprising a polymer (C1) and a polymer (C2) represented by the following general formula (2) has a primary particle diameter of 0.01 to 0.5 μm.
A non-magnetic one-component developing method characterized by holding zinc oxide powder.

Embedded image Wherein R ₁ is a C ₁₁ -C ₁₇ hydrocarbon group, R ₂ and R ₃ are each independently hydrogen or a C ₁ -C ₈ hydrocarbon group, or R ₂ and R ₃ are They may be connected to each other to form an aromatic ring. R ₄ represents a C ₁ -C ₁₂ alkylene group which may contain an ether bond in the group,
X ^- is an anion, m represents an integer of 2 to 100. ]

Embedded image [Wherein, R _{1 to} R ₄ and X ⁻ are the same as those in the general formula (1), and n represents an integer of 2 to 100]. ]

Hereinafter, the present invention will be described in detail. FIG.
FIG. 1 is a schematic configuration diagram of a developing device used in a non-contact non-magnetic one-component developing method of the present invention. In the figure, 1 is a photosensitive drum,
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 the non-magnetic one-component developer, and 6 is leakage prevention of the non-magnetic one-component developer. And a toner scraping member 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. The non-magnetic one-component developer 3 is supported on the developing roller 5 by a layer regulating member 4 so as to have a constant layer thickness. Electric charge is applied by friction with the regulating member 4.
The developing roller 5 is provided between the photosensitive drum 1 and 50 μm to 200 μm.
It is installed through a gap of μm. The rollers include
Apply a DC or AC voltage bias. The non-magnetic one-component developer carried on the developing roller 5 is transported by the rotation of the developing roller 5 and flies to the surface of the photosensitive drum 1 due to a potential difference between the photosensitive drum 1 having an electrostatic latent image and the developing roller 5. Then, the electrostatic latent image is visualized in a non-contact manner. 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 a layer regulating member. However, when a metal blade is used, local toner fusion easily occurs on the layer regulating member and the developing roller. It was confirmed that when a rubber blade was used, such local toner fusion hardly occurred. Although the cause is not necessarily clear, in the present invention, it is preferable to roughen the developing roller as described below, and when the roughened developing roller is used, the convex portions and the layer on the developing roller surface are used. In contact with the regulating member, it is presumed that the local compressive force and the shearing force are stronger in the case of the metal blade than in the case of the rubber blade. In the case of a metal blade, it is estimated that fusion occurs easily because high stress is applied to the toner particles when the toner passes through such a high stress portion. On the other hand, in the case of the rubber blade, the followability to the unevenness of the surface of the developing roller is good, and the stress difference between the concave portion and the convex portion is smaller than in the case of the metal blade. It is presumed that it is hard to cause wearing. In the present invention, the developing roller has an Rz of 0.5 to 15 μm and an Rz of
It is preferable that the surface is roughened to a max of 20 μm or less. R
When z is less than 0.5 μm, the toner layer is not formed to an extent necessary for development, and the amount of development tends to be insufficient. On the other hand, R
If z is greater than 15 μm, the toner may be clogged in the roughened concave portions, which is a factor that hinders the charging of the toner during continuous imaging, which is not preferable. It has been found that when the Rz of the developing roller surface in the present invention is in the range of 0.5 to 15 μm, the toner layer thickness is sufficiently large, good developability is obtained, and clogging of the toner hardly occurs. Even when Rz is in the range of 0.5 to 15 μm, Rma
If there is a local unevenness such that x exceeds 20 μm, clogging of the toner tends to occur at that portion, which is not preferable for the same reason as described above. The surface roughness of the developing roller was 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 smaller the gap is, the better the developing property is. However, if the gap is less than 50 μm, it is extremely difficult to control the precision of the production mechanism, which is not preferable. On the other hand, when it is wider than 200 μm, it is difficult to obtain a sufficient electric field intensity 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. Non-magnetic one-component developer is a binder resin,
A colorant and a graft polymer (C1) having a polystyrene-based main chain in which 50 mol% or more of the constituent monomers are styrene and a graft chain having a skeleton represented by the general formula (1); Or the graft polymer (C
This is a positively chargeable nonmagnetic toner mainly composed of a charge control agent comprising the polymer (C2) represented by 1) and the general formula (2), and holding a metal oxide powder on the surface thereof. Examples of the binder resin of the positively-chargeable non-magnetic toner include polystyrene, polyester, acrylic resin, styrene-acrylic copolymer, ethylene-vinyl chloride copolymer, polyamide, polyethylene, maleic resin, xylene resin,
Examples include, but are not limited to, phenolic resins.

Examples of the colorant include black colorants such as carbon black, acetylene black, lamp black, channel black, and aniline black;
If a chromatic color, there may be mentioned Farnal Blue, Permanent Blue, Nigrosine Blue, phthalocyanine cyan pigment, rose bengal, xanthene magenta dye, quinacridone magenta pigment, monoazo red pigment, disazo yellow pigment, etc. However, the present invention is not limited to these. These colorants are appropriately blended in the range of 1 to 20 parts by weight based on 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 charge control agent used in the present invention
Is obtained by introducing a graft chain represented by the general formula (1) into a functional group portion of a styrene-based resin having a functional group, and the polystyrene-based main chain is a functional group of a styrene-based resin having a functional group. It is 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 for R ₁ include an alkyl group, an alkenyl group, and an alkylphenyl group. Examples of the hydrogen of R ₂ and R ₃ or the hydrocarbon group of C _{1 to} C ₈ include hydrogen, an alkyl group, an aryl group, and an aralkyl group. 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-based main chain, that is, the number average degree of polymerization of the styrene-based 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 is composed of the graft polymer (C1) or composed of the graft polymer (C1) and the polymer (C2). The polymer (C2) is a homopolymer obtained by homopolymerizing a part of the graft chain of the graft polymer (C1) without bonding to the main chain. The homopolymer has a number average degree of polymerization n of 2 to 100. The composition ratio of each component in the charge control agent is, in terms of the weight ratio of the graft chain constituting the graft polymer (C1) and the polymer (C2), 25 to 100% of the graft polymer (C1), When the polymer (C2) is 0
75%. The charge control agent used in the present invention is used in an amount of 1 to 20 parts by weight, preferably 2 to 15 parts by weight, based on 100 parts by weight of the binder resin. If the amount 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, the amount exceeds the appropriate amount of triboelectric charging, and the image density may not be sufficiently obtained. The positively chargeable non-magnetic toner may optionally contain other components such as additives such as low molecular weight polypropylene, silicone oil, and thermoplastic silicone resin. Further, one or more kinds of charge control agents such as a nigrosine dye and a quaternary ammonium salt may be contained.
The positively chargeable non-magnetic toner preferably has a volume average particle diameter of 12 μm or less, preferably 3 to 10 μm, and if the volume average particle diameter 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 fine lines and characters may deteriorate.
A positively chargeable non-magnetic toner is prepared by mixing a binder resin, a colorant, a charge control agent and, if desired, other raw materials prepared at a predetermined mixing ratio with an extruder, a Banbury mixer, and a melt kneader. It is obtained by melt-kneading with a shaft kneader or the like, followed by pulverization and classification. The specific charge control agent characteristic of the present invention can be finely dispersed easily in the binder resin by the above-described melt-kneading means. In particular, when polystyrene or a styrene-acrylic copolymer is used as the binder resin, the compatibility between the polystyrene-based main chain contained in the charge control agent and the binder resin is good, so that the charge control agent is more likely to be used. It is preferable because uniform fine dispersion is possible.
As a means for obtaining a positively-chargeable non-magnetic toner, it is also possible to obtain a positively-charged non-magnetic toner by a polymerization method such as suspension and emulsification. 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 referred to as a positively chargeable non-magnetic toner.

[0009] As the metal oxide powder to be retained on the positively chargeable non-magnetic surface of the toner, in order to obtain the effect of the present invention is especially likely have positively chargeable, zinc oxide (ZnO) is
Used. The amount of the zinc oxide powder to be added to the positively chargeable nonmagnetic toner is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the positively chargeable nonmagnetic toner. If the amount is less than 0.1 part by weight, the adhesive force between the non-magnetic one-component developer particles or between the non-magnetic one-component developer and the developing roller is so strong that a practically sufficient image density may not be obtained. On the other hand, if the amount is more than 5 parts by weight, the amount of triboelectricity of the non-magnetic one-component developer is too low, so that it is difficult to form a good thin toner layer on the developing roller, and toner scattering from the developing machine may increase. is there. The zinc oxide powder has a primary particle size of 0.01 to 0.5 μm.
it is necessary to be a m. If the primary particle diameter of the zinc oxide powder is less than 0.01 μm, the holding property to the positively chargeable non-magnetic toner may be poor, and if it exceeds 0.5 μm, the uniform holding property to the positively chargeable non-magnetic toner may be poor. Although good, the holding power is apt 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 zinc oxide powder on the surface of the positively chargeable non-magnetic toner, a positively chargeable non-magnetic toner having a predetermined mixing ratio using a mixer such as a Henschel mixer, a super mixer or the like for powder is used. It can be performed by stirring the mixture with the zinc oxide powder. When using a mixer such as a Henschel mixer or a super mixer, mixing may be performed for a relatively short time under mild stirring conditions. In the present invention, the expression “holding the zinc oxide powder on the surface of the positively chargeable non-magnetic toner” means that the zinc oxide powder is electrostatically attached to the surface of the positively chargeable non-magnetic toner (the surface is dusted). Condition) and acid
Zinc powdered is intended to include a state in which is embedded (state of being fixed), in particular the surface of zinc oxide powder positively charged non-magnetic toner 8 as all or part of the zinc oxide powder is shown in FIG. 2 The state where 9 is not embedded and is electrostatically attached is preferable. When held in a state as shown in FIG. 2, repulsion and agglomeration of the non-magnetic one-component developer particles due to electrostatic force are reduced, and a good thin toner layer can be formed on the developing roller. . Further, a fluidity improver such as hydrophobic silica for adjusting fluidity is used.
It can be added simultaneously with the zinc oxide powder. In this case, the same powder mixer as described above can be used.

[0010]

In the non-contact developing method using a non-magnetic one-component developer having a positive polarity, the amount of triboelectric charge of a positively-chargeable non-magnetic toner used as a non-magnetic one-component developer is improved in order to improve flying developability. It is necessary to keep it low on the positive polarity side. However, if the triboelectric charge is too low, problems such as fogging and toner scattering tend to occur. For this reason, the triboelectric charge amount of the non-magnetic one-component developer as a whole is relatively low, and the triboelectric charge amount of each non-magnetic one-component developer particle is approximately the same, and the width of the triboelectric charge distribution is narrow and sharp. There is a need to. The specific charge control agent used in the present invention can be very finely dispersed in the binder resin, can narrow the triboelectric charge distribution, and simultaneously suppress the triboelectric charge to a low level. , It is possible to obtain good developability. Also,
In order 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 zinc 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. Also,
Since the zinc oxide powder in the present invention has a relatively positive chargeability, when it is held on the surface of the positively chargeable nonmagnetic toner particles, it is difficult to generate toner particles of the opposite polarity, and matching with the charge control agent described above. And developability can be improved. In addition, by holding the zinc oxide powder on the surface of the positively-chargeable non-magnetic toner, the contact distance between the non-magnetic one-component developer particles and between the particles and the developing roller is increased, thereby preventing aggregation between the particles. And developability is improved. Further, when the toner particle diameter is small, the amount of triboelectric charge on the developing roller increases, and the developability deteriorates.In the case of the present invention, by holding the zinc oxide powder on the surface of the positively chargeable non-magnetic toner, The amount of triboelectric charge can be controlled in an appropriate range, and the developability is improved.

[0011]

The present invention will be described below with reference to examples. In the examples, parts are parts by weight. Example 1 794 parts of styrene, 160 parts of butyl acrylate and 46 parts of chloromethylstyrene were dissolved in toluene, and this was mixed with 30 parts of azobisisobutyronitrile while controlling the polymerization temperature to the boiling point of toluene and used as a polymerization initiator. Polymerized,
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 17000. 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 benzoyl chloride was added, and the mixture was refluxed for 4 hours. After the completion of the reaction, the reaction product was added to an aqueous solution in which 205 parts of p-toluenesulfonic acid was dissolved in 2,000 parts of water while stirring with a homomixer. The precipitate is washed with water, filtered, dried and
A charge control agent containing a graft polymer (C1) having a graft chain represented by the following general formula was obtained.

Embedded image Next, the raw materials were mixed in the following composition, 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 (made by Mitsui Kinzoku Co., Ltd .: Pastrun t)
ypeII 2410 primary particle size 0.02 μm).
0 parts were added and stirred with a Henschel mixer for 2 minutes to obtain a non-magnetic one-component developer.・ Styrene-acrylic copolymer resin 100 parts (monomer styrene / butyl acrylate / n-butyl methacrylate = 78/18/4, Mn: 2.9 × 10 ⁴ , Mw: 32.8 × 1 manufactured by Fujikura Kasei Co., Ltd.) 0 ⁴⁾ carbon black 10 parts (by Cabot Corporation, trade name: BPL) above charge control agent 8 parts polypropylene wax 2 parts (manufactured by Sanyo Chemical Industries, Ltd. trade name: Viscol 660P)

Example 2 100 parts of the positively chargeable non-magnetic toner obtained in Example 1 was applied to zinc oxide (trade name: Pastrun type II, manufactured by Mitsui Kinzoku Co., Ltd.)
2410 (primary particle diameter 0.02 μm) and 1.0 part of hydrophobic alumina (trade name: RFY- manufactured by Nippon Aerosil Co., Ltd.)
0.5 part of C) was added simultaneously, 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., degree of polymerization: about 200
(0, degree of saponification: about 80%) was adjusted to 1% in water and sodium sulfate was adjusted to 3% in water to prepare an aqueous medium. On the other hand, 2,2 ′ was added to a monomer composition composed of 4000 g of styrene and 1000 g of butyl acrylate.
-A mixed solution in which 15 g of azobisisobutyronitrile was dissolved was prepared, and 400 g of carbon black (trade name: # 40, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) and 150 g of the charge control agent obtained in Example 1 were added to the mixed solution. The mixture was dispersed by an ultrasonic disperser for 30 minutes to prepare a dispersion. Next, the above dispersion was added to 10
The aqueous medium was fed to the granulator at a flow rate of 0 ml / min and at a flow rate of 400 ml / min via separate channels for 10 minutes. A granulator having a rotating part with a diameter of 50 mm is used.
The mixture of the dispersion and the aqueous medium was stirred under the condition of 00 rpm. Then, the mixed solution passed through the granulator was guided into a polymerization tank while being stirred at 300 rpm by a turbine type stirring blade, and reacted for 8 hours. Thereafter, the polymer particles were separated by a centrifugal dehydrator, washed sufficiently with water, and dried to obtain a positively chargeable non-magnetic toner composed of the polymer particles. The volume average particle size of the positively chargeable non-magnetic toner was 6.5 μm. Next, 100 parts of the positively-chargeable non-magnetic toner is coated with zinc oxide (trade name: Pastrun type II 2 manufactured by Mitsui Kinzoku Co., Ltd.)
410 primary particle diameter 0.02 μm) and 1.0 part of hydrophobic alumina (trade name: RFY-C, manufactured by Nippon Aerosil Co., Ltd.)
Was added simultaneously 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 directly used as a non-magnetic one-component developer for comparison.

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

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

Using a non-magnetic one-component developer obtained by the above operation, a remodeling machine (developing bias of direct current) of a commercially available laser beam printer (L-880, manufactured by Kyocera Corporation) having the developing device of FIG. The voltage was changed to -100 V and the surface potential of the photosensitive drum was changed to -900 V, and the development was changed to regular development. The layer regulating member was made of a rubber blade made of urethane, and the surface of the developing roller was subjected to surface treatment by sandblasting to roughen the surface. Was 6 μm and Rmax was 17 μm, and the gap between the photosensitive drum and the developing roller was 120 μm). As a result, each of the non-magnetic one-component developers of Examples 1 to 3 formed a uniform thin layer on the developing roller. When the solid image of the non-magnetic one-component developer transferred from the photosensitive drum onto the transfer paper was measured with a Macbeth reflection densitometer (trade name: RD-914, manufactured by Macbeth), 1.3 was obtained in Example 1.
5. It was found that a good image density of 1.39 was obtained in Example 2 and 1.34 in Example 3, and a sufficient amount of non-magnetic one-component developer was flying from the developing roller to the photosensitive drum. Supported. In contrast, Comparative Examples 1 and 2
The non-magnetic one-component developer does not form a uniform thin layer on the developing roller and has a high triboelectric charge. When a solid image is measured with a Macbeth reflection densitometer, Comparative Example 1 is 0.75, Comparative Example No. 2 has 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. In addition, the non-magnetic one-component developer of Comparative Example 3 cannot form a uniform thin layer on the developing roller,
Since the developer hardly flies on the transfer paper, the image density of the solid image cannot 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 non-magnetic one-component developer has a small adhesive force to the developing sleeve. It is presumed that the formation of the thin layer on the developing sleeve became defective.

[0018]

As described above, the present invention provides a positively chargeable non-magnetic toner containing a specific charge controlling agent on a surface of a specific particle size.
By using the non-magnetic one-component developer holding the zinc oxide powder having the following, a uniform thin toner layer can be obtained on the developing roller, and even if the non-magnetic one-component developer has a small particle diameter, it is satisfactory. High developability can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a state where a toner is held on a surface of a positively chargeable nonmagnetic toner.
It is the schematic diagram which showed the state of the zinc oxide powder.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoreceptor 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 Zinc oxide powder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 9/097 G03G 9/08 G03G 15/08

Claims (3)

(57) [Claims] 1. A non-magnetic one-component developer is supplied to a developing roller, and a thin layer of the non-magnetic one-component developer is formed on a surface of the developing roller by a layer regulating member and is given an electric charge. 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 with the photosensitive drum holding an electrostatic latent image in a non-contact manner, and then transferred to a transfer material. The non-magnetic one-component developer contains 50% of a binder resin, a colorant and a constituent monomer.
A polystyrene-based main chain in which at least mol% is styrene,
It consists 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) The primary particle diameter is 0.01 to 0.5 μm on the surface of a positively chargeable non-magnetic toner mainly composed of a charge control agent comprising
a non-magnetic one-component developing method characterized by holding a zinc oxide powder of m . Embedded image Wherein R ₁ is a C ₁₁ -C ₁₇ hydrocarbon group, R ₂ and R ₃ are each independently hydrogen or a C ₁ -C ₈ hydrocarbon group, or R ₂ and R ₃ are They may be connected to each other to form an aromatic ring. R ₄ represents a C ₁ -C ₁₂ alkylene group which may contain an ether bond in the group,
X ^- is an anion, m represents an integer of 2 to 100. ] [Wherein, R _{1 to} R ₄ and X ⁻ are the same as those in the general formula (1), and n represents an integer of 2 to 100]. ] 2. The method according to claim 1, wherein the layer regulating member is a rubber blade, the surface of the developing roller is roughened, and a gap between the photosensitive drum and the developing roller is 50 to 200 μm. Non-magnetic one-component development method. 3. The non-magnetic one-component developing method according to claim 2 , wherein the surface of the developing roller is roughened at an Rz of 0.5 to 15 μm and an Rmax of 20 μm or less.