JPH07319274A - Reversal image forming method and developer - Google Patents

Abstract

PURPOSE:To prevent production of edge fringes in the coating system of fatty acid metal salt on an org. photoreceptor in a reversal developing system by constituting the method to include a unit to supply a fatty acid metallic salt having specified water content on the photosensitive body and a unit to recycle a part of the supplied fatty acid metal salt to the developing unit. CONSTITUTION:An electrostatic latent image is formed on an org. photoreceptor 14 and processed for reversal development with a developer. This image forming method a unit to supply a fatty acid metallic salt having 10-500ppm water content to the photoreceptor and a unit to recycle a part of the supplied fatty acid metal salt to a developing unit. To control the water content of the fatty acid metallic salt, the fatty acid metallic salt is preliminarily stored for a long time at low temp. and low humidity, or dried under reduced pressure. Since stress is once added to the fatty acid metallic salt to be recycled, the fatty acid metallic salt shows intense cleavage property. When the recycled fatty acid metallic salt is applied on the photosensitive body, an extremely uniform thin layer can be formed which suppresses reduction of the surface potential as little as possible and gives an effect to prevent edge fringes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer,
The present invention relates to an electrophotographic technique applied to electrostatic printing or the like, and more specifically to a reversal image forming method and a developer.

[0002]

2. Description of the Related Art Conventionally, in a toner for developing an electrostatic latent image formed on an organic photoconductor, inorganic fine particles (alumina,
Those containing a titania, silica) and a fatty acid metal salt have been proposed (JP-A-62-209538 and JP-A-62-2095).
No. 39). Its purpose is to perform a proper polishing action for removing the toner binder resin adhering to the surface of the organic photoreceptor and the paper dust emitted from the transfer paper. It also has an effect of removing an aged portion on the surface of the photoreceptor due to active oxygen such as ozone generated by corona discharge.

Even in digital reversal development, there is an example in which a fatty acid metal salt is used for the purpose of preventing deterioration of the photoreceptor (JP-A-63-85581). However, when the fatty acid metal salt is applied to the organic photoconductor in the reversal development system, the problem of "tip fringe" is likely to occur. The "leading edge fringe" refers to a phenomenon in which toner is developed by opening a gap at the leading edge of an image (the leading edge refers to the upstream side in the sheet passing direction).

[0004]

It is presumed that the above phenomenon occurs because the toner developed on the photoconductor moves due to the rubbing force of the developer. When a fatty acid metal salt is applied, the friction coefficient on the surface of the photoconductor is basically lowered, and in the reversal development system, the surface potential is lowered and the force for holding the toner on the photoconductor is lowered, so that the toner easily moves. Conceivable. Therefore, in the reversal development system, it is necessary to control the application state of the fatty acid metal salt more precisely than in the conventional regular development.

Further, in a digital latent image formed by dots, "tip fringe" is generated at all the tips of the dots, so that this problem is great not only in a solid image but also in a halftone formed by a set of dots. .

On the other hand, among the conventional fatty acid metal salts having a high water content, this "tip fringe" phenomenon was particularly remarkable.

Further, conventionally, the fatty acid metal salt accumulated in the cleaning unit or the like was discarded together with the waste toner, and there was a problem in terms of environmental protection. Further, since the coating efficiency is poor, when the amount of the fatty acid metal salt supplied is excessive, there is a problem that the chargeability of the developer is adversely affected.

The present invention has been made to solve the above problems.

[0009]

The object of the present invention is achieved by adopting the following constitution.

(1) An electrostatic latent image is formed on an organic photoconductor,
In the image forming method of reversal developing the latent image using a developer, a unit for supplying a fatty acid metal salt having a water content of 10 to 500 ppm onto the photoreceptor and at least a part of the supplied fatty acid metal salt are recycled to the developing unit. A reverse image forming method, comprising:

(2) In an image forming method in which a digital latent image is formed on an organic photoconductor, the latent image is reversely developed with a developer, and then the toner not transferred to the transfer body is recycled to a developing unit. , At least a water content of 10 ~
A developer containing 500 ppm of a fatty acid metal salt.

Means for controlling the water content of the fatty acid metal salt to 10 to 500 ppm may be such that the fatty acid metal salt to be used is left to stand at low temperature and low humidity for a long time or dried under reduced pressure.

The water content in the present invention is measured by the Karl Fischer coulometric titration method. Hiranuma Sangyo Co., Ltd.
An automatic heating vaporized water content measuring system AQS-724 manufactured by the same company was used.

Specifically, 0.5 g of the sample is 20 ml made of glass.
A sample tube is precisely weighed and covered with a silicone rubber packing whose surface is coated with Teflon. At this time, in order to correct the amount of water contained in the air, two empty sample tubes covered with the same packing are prepared at the same time when the lid is covered.

Water sent from the moisture vaporizer was titrated under conditions of a heating temperature of 110 ° C. and a carrier gas (nitrogen gas) flow rate of 150 ml / min under the conditions of INTERVAL of 25 seconds and TIMER of 1 minute. Hydranal aqualite RS was used as the generation liquid, and aqualite C was used as the counter electrode liquid.

Calculation of water content (ppm) follows the following formula

[0017]

[Equation 1]

A: Water content (g) detected from the sample tube containing the sample B: Average water content (g) detected from two empty sample tubes C: Sample amount (g) Fatty acid metal salt It is presumed that the decrease in the surface potential of the photoconductor after coating is caused by the low electric resistance of the fatty acid metal salt. When a fatty acid metal salt having an extremely low water content is used, the electric resistance can be increased, and as a result, "tip fringe" peculiar to the reversal development system is unlikely to occur. However, if the water content is too low, the uniform coating property will be impaired, so control of this water content is particularly important in reversal development.

It goes without saying that recycling the fatty acid metal salt accumulated in the cleaning unit or the like to the developing unit has the effect of increasing the coating efficiency and environmental protection, but we have found that recycling produces a surprising effect. It was The fatty acid metal salt to be recycled is highly stressed since it is once stressed, and when this is recycled to the developing unit and supplied again to the photoreceptor, it is possible to form an extremely uniform thin layer. Therefore, the decrease of the surface potential can be suppressed to the minimum, which is effective in preventing "tip fringe".

In the present invention, preferred compounds, working conditions, devices and the like are as follows.

1. Fatty acid metal salts Zinc stearate and lithium stearate are particularly preferable because the effect is long-lasting since moisture absorption is less likely to occur after the water content is reduced due to its low affinity with water.

Further, as the range of water content, 10 to 100 ppm shows better characteristics.

2. Supply unit of fatty acid metal salt Although the solid fatty acid metal salt may be formed into a columnar shape and directly pressed onto the photoconductor, the apparatus is a method in which it is present in the toner and supplied onto the photoconductor during development, and pressure coating is performed with an elastic blade or the like. It is preferable because it does not become large and the fatty acid metal salt is uniformly applied.

When it is present in the toner, the addition amount is preferably 0.01 to 0.10% by weight with respect to the toner.

Since the fatty acid metal salt remaining after coating is recycled, the addition amount is not required to be so large. This also has a secondary effect that the charging properties of the toner and carrier are less affected. The volume average particle diameter of the fatty acid metal salt particles in that case is appropriately 0.1 to 20 μm,
Particularly, 0.5 to 10 μm is preferable. If it is too small, it is difficult to form a coating film, and if it is too large, the coating film becomes thick and uneven.

When the fatty acid metal salt particles supplied onto the photoconductor are pressure coated with an elastic blade or the like, the linear pressure is 6 to 23 g.
/ Cm is appropriate. If the pressure is lower than this, the fatty acid metal salt will not be applied uniformly, and if it is too high, uneven application will tend to occur in the axial direction of the photoreceptor.

The contact angle of the elastic blade is preferably 6 to 25 °. When the contact angle is small, the fatty acid metal salt particles slip off, resulting in poor coating efficiency. When the contact angle is too large, the elastic blade tends to bounce and uneven coating occurs in the circumferential direction of the photoreceptor. Cause

3. Fatty Acid Metal Salt Recycling Unit The fatty acid metal salt sent to the cleaning unit is preferably returned to the developing device together with the recovered toner by a screw pipe or the like, or is returned to the toner replenishing unit and then supplied to the developing device.

Further, if a heater or a desiccant such as silica gel is installed between the supply unit and the recycle unit or in any place so that the once dehydrated fatty acid metal salt does not absorb moisture again, the effect is more easily exhibited. .

4. Developing condition Since the cause of "tip fringe" is the frictional force of the developer, it is preferable that the gap between the photoconductor and the developer carrying member is as large as possible from the viewpoint of the effect of the present invention. Since there is a tradeoff, 300 to 1000 μm is preferable.

Further, it is preferable that the ratio of the peripheral speed of the developer-carrying member / the peripheral speed of the photosensitive member is as close as possible to 1, but this is also in consideration of the developing property, and practically 1 to 3 is preferable. , Particularly preferably in the range of 1-2.

It is preferable that the amount of charge of the developer used in the present invention is as high as possible, because the electrostatic attraction between the toner and the photoconductor is large and it is difficult to scrape it. However, if it is too high, the development density will be low, so 10 to 30 μC / g can be said to be a preferable range.

The charge amount of the developer in this case was measured by the usual blow-off method.

[0034]

Next, the photoconductor, developer, image forming apparatus and the like used in the present invention will be specifically illustrated as follows.

<Photoreceptor Used in the Present Invention> As described above, the organic photoreceptor is preferable, and among them, the so-called function-separated type which is composed of both the charge generating substance and the charge transporting substance is preferable. A multi-layered type in which each of these is a separate layer,
Although there are single-layer type and the like in which both are added to the same layer, many multi-layer type are made today.

In the photoreceptor of the present invention, the pigments represented by the following representative examples are used as the charge generating substance (CGM).

(1) Azo pigments such as monoazo pigments, bisazo pigments, triazo pigments and metal complex salt azo pigments (2) Perylene pigments such as perylene anhydride, perylene imide (3) Anthraquinone derivatives, anthanthrone derivatives, dibenz Polycyclic quinone pigments such as pyrenequinone derivatives, pyranthrone derivatives, violanthrone derivatives and isobiolanthrone derivatives (4) Indigoid pigments such as indigo derivatives and thioindigo derivatives (5) Phthalocyanine pigments such as metal phthalocyanines and metal-free phthalocyanines The charge generating substance preferably used in the present invention is described in
Polycyclic quinone pigments described in 59-184353, more preferably dibromoanthanthrone pigment, or JP-A 2-20877.
Bisazo pigments, more preferably fluorenone type bisazo pigments represented by the general formula [III], halogen-substituted perylene pigments described in JP-B-3-26384, JP-A-62-54267. Asymmetric perylene pigments described in JP-A Nos. 54-126036, 58-152247, and 59-319.
The perylene pigments described in Nos. 57, 2-251858, 4-62560 and 5-6014, and the bisimidazopyridonoperylene pigments described in Japanese Patent Application No. 3-279764 are preferable.

Further, α-type titanyl phthalocyanine described in JP-A-61-239248, β-type titanyl phthalocyanine described in JP-A-62-67094, C-type titanyl phthalocyanine described in JP-A-63-366, and JP-A-2-309362. I-type titanyl phthalocyanine described in Japanese Patent Application No. 62-173640 is more preferable.

Examples of the binder used in the charge generation layer of the present invention include the following.

(1) Polyester (2) Methacrylic resin (3) Acrylic resin (4) Polyvinyl chloride (5) Polyvinylidene chloride (6) Polystyrene (7) Polyvinyl acetate (8) Styrene copolymer resin (for example, styrene- Butadiene copolymer, styrene-methyl methacrylate copolymer, etc.) (9) Acrylonitrile-based copolymer resin (for example, vinylidene chloride-acrylonitrile copolymer, etc.) (10) Vinyl chloride-vinyl acetate copolymer ( 11) Vinyl chloride-vinyl acetate-maleic anhydride copolymer (12) Silicone resin (13) Silicone-alkyd resin (14) Phenolic resin (for example, phenol-formaldehyde resin, cresol-formaldehyde resin, etc.) (15) Styrene- Alkyd resin (16) Poly-N-vinylcarbazole (17) Polyvinyl butyral (18) Polyvinyl formal (19) Poly Mud alkoxy styrene These binders may be used together, alone or in combination of two or more.

Generally, the charge transport layer comprises a charge transport material,
The charge transport material is not particularly limited. For example, oxazole derivative, oxadiazole derivative, thiazole derivative, thiadiazole derivative, triazole derivative, imidazole derivative, imidazolone derivative, imidazolidine derivative, bisimidazolidine derivative, styryl compound, hydrazone compound, pyrazoline derivative, amine derivative, oxazolone derivative, benzothiazole Derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, poly-N-vinylcarbazole,
Examples thereof include poly-1-vinylpyrene and poly-9-vinylanthracene.

In the present invention, as the binder of the charge transport layer, the binder used in the charge generation layer described above can be used in addition to the polycarbonate resin and the like. Among them, the BPZ type polycarbonate resin represented by the following formula is particularly preferable because of the uniform thin film form of the fatty acid metal salt.
The charge transport layer is dissolved in the above-mentioned organic solvent and applied on the charge generation layer.

[0043]

[Chemical 1]

In addition, the photoreceptor of the present invention may further contain an ultraviolet absorber or the like for the purpose of protecting the photosensitive layer, if necessary, and may further contain a dye for color sensitivity correction.

Further, in the present invention, an intermediate layer may be provided between the substrate and the charge generating layer, if necessary. The intermediate layer functions as an adhesive layer or a blocking layer, and in addition to the binder resin, for example, polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride. Copolymers, casein, alcohol-soluble nylon, starch and the like are used.

In the present invention, the photosensitive layer may contain one or more electron-accepting substances for the purpose of improving sensitivity, reducing residual potential and reducing fatigue during repeated use.

Examples of the electron accepting substance that can be used here include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride and 3-nitrophthalic anhydride. Acid, 4-nitrophthalic anhydride, pyromellitic dianhydride,
Mellitic anhydride, tetracyanoethylene, tetracyanoquinone dimethane, o-dinitrobenzene, m-dinitrobenzene, 1,3,5-trinitrobenzene, paranitrobenzonitrile, picryl chloride, quinone chlorimide, chloranil, bulmannyl, Dichlorodicyanoparabenzoquinone, anthraquinone, dinitroanthraquinone, 2,7-
Dinitrofluorenone, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 9-fluorenylidene (dicyanomethylene malonodinitrile), polynitro-9-fluorenylidene- (dicyanomethylene malonodinitrile), Picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, phthalic acid, melitic acid, and other electron affinities Can be mentioned. Further, the addition ratio of the electron-accepting substance is a weight ratio of the organic pigment used in the present invention: the electron-accepting substance = 100: 0.01 to 200, preferably 100: 0.1 to 100.
Is.

Further, organic amines can be added to the photosensitive layer of the present invention for the purpose of improving the charge generation function of CGM, and it is particularly preferable to add a secondary amine. These compounds are described in JP-A-59-218447 and JP-A-62-8160.

As the electroconductive substrate used in the construction of the electrophotographic photosensitive member of the present invention, the following are mainly used, but not limited thereto.

1) Metal plate such as aluminum plate, stainless plate, etc. 2) On a support such as paper or plastic film,
A thin metal layer such as aluminum, palladium, or gold provided by lamination or vapor deposition 3) On a support such as paper or plastic film,
Examples thereof include those in which a layer of a conductive compound such as a conductive polymer, indium oxide or tin oxide is provided by coating or vapor deposition.

<Image Forming Method> FIG. 1 shows an example of an image forming method applicable to the image forming method of the present invention. Reference numeral 14 denotes an electrostatic charge image bearing member, and this electrostatic charge image bearing member 14 has a shape of a rotary drum, and an organic photoreceptor is particularly preferable from the viewpoint of easy disposal. A charger 1, an exposure optical system 2, a developing device 12, a transfer device 5, a separator 6, and a cleaning device 15 are arranged in this order from the upstream side to the downstream side in the rotation direction around the photoconductor. 10 is a fixing device.

In this image forming apparatus, the surface of the electrostatic image carrier 14 is charged to a uniform potential by the charger 1.
Then, it is imagewise exposed by the exposure optical system 2 to form an electrostatic latent image on the surface of the electrostatic image carrier 14. And the developing device
By the developer containing the toner and the carrier contained in 12 (the developing method is not particularly limited, usually the two-component developing method is often used), the above electrostatic latent image is developed to form a toner image. To be done. This toner image is electrostatically transferred onto the recording material P by the transfer device 5, and is heat-fixed by the heat roller fixing device 10 to form a fixed image. On the other hand, the photoconductor 7 that has passed through the transfer device 5 is cleaned of residual toner by the cleaning device 15 and is used for forming the next image. Further, the toner collected by the cleaning device is returned to the developing device 12 and / or the toner replenishing box 11 again by the toner recycling system described later and is reused.

A concrete example of the toner recycling system is shown in FIG.
And 3 are shown. In this example, 12 is a developing device, 13 is a developing sleeve, 14 is a photoconductor, 15 is a cleaning device, 16 is a toner carrying screw 1, 17 is a toner carrying screw 2,
Reference numeral 18 is a toner conveying screw 3, and 20 is a toner supply box. The apparatus of this example includes toner conveying screws 1, 2, 3
The toner collected by the cleaning device is sequentially conveyed by and is supplied to the distributor 19 for exclusive use of recycled toner (separate from the new toner supply port) provided in the developing device. That is, 16 toner conveying screws 1, 17
Each of the toner conveying screws 2 and 18 of the toner conveying screw 3 has a rotary shaft inside and a blade provided spirally along the rotary shaft, and the toner is sequentially conveyed by the blades as the rotary shaft rotates. The toner that has been collected and supplied to the distributor 19 is again used for latent image development on the photoconductor 14.

On the other hand, 12 to 18 and 20 in FIG. 3 are the same as those in FIG.
In the apparatus of this example, toner collected by the cleaning section is successively conveyed by the toner conveying screws 1, 2 and 3 and supplied to the toner supply box. The difference from FIG. 2 of this example is that the new toner and the recycled toner collected in the toner supply box are stirred and mixed in advance and then supplied to the developing device.

<Cleaning Device> As the cleaning device, a blade cleaning device can be preferably used. The contact angle of the cleaning blade with the organic photoreceptor is preferably in the range of 6 to 25 °.
If the contact angle is less than 6 °, the transfer residual toner remaining on the organic photoreceptor cannot be sufficiently cleaned. On the other hand, if the contact angle is larger than 25 °, the rubbing force between the cleaning blade and the organic photoconductor becomes large, so that the surface of the organic photoconductor becomes excessively worn or the cleaning blade is turned over.

The pressing load is preferably in the range of 6 to 23 g / cm. If the pressing load is less than 6 g / cm, the transfer residual toner remaining on the organic photoconductor cannot be sufficiently cleaned. In addition, the pressing load
If it exceeds 23 g / cm, the surface of the organic photoconductor is likely to be scratched.

<Carrier used in the present invention> The carrier is not particularly limited, but a non-coated carrier made of magnetic particles, a resin-coated carrier obtained by coating a core particle such as magnetic particles with a resin, a magnetic material is a resin. A magnetic material-dispersed carrier or the like dispersed therein can be used, and among these, a resin-coated carrier having a resin coating is preferably used.

As the magnetic particles constituting the carrier,
A substance that is strongly magnetized in that direction by a magnetic field, such as iron,
Ferromagnetic metals such as ferrite and magnetite, metals or alloys exhibiting ferromagnetism such as nickel and cobalt, or compounds containing these elements are used. Or, from an alloy that does not contain a ferromagnetic element, but becomes ferromagnetic by proper heat treatment, for example, an alloy of a type called a Heusler alloy such as manganese-copper-aluminum or manganese-copper-tin, or chromium dioxide. Can be used.

Here, ferrite is a general term for magnetic oxides containing iron, and is not limited to spinel type ferrite represented by the chemical formula of MO.Fe ₂ O ₃ (M is a divalent metal). This ferrite can be preferably used in the present invention because various magnetic properties can be obtained by changing the composition of the contained metal component. Copper because it has a higher electrical resistance and exhibits superior triboelectric charging properties than manganese-zinc ferrite and nickel-zinc ferrite
-Zinc-based ferrite is particularly preferable. In addition, since ferrite is an oxide, its specific gravity is smaller and lighter than metals such as iron and nickel, so it is easy to mix with toner and agitate, and it is possible to make the toner concentration uniform and the triboelectric charge uniform. To achieve the above.

As the coating resin for the resin-coated carrier or the binder resin for the magnetic substance-dispersed carrier, for example, styrene-acrylic resin, silicone resin, or fluorine resin can be used.

The volume average particle diameter of the carrier is preferably 30 to 80 μm. The volume average particle size of this carrier is 30μ
When it is less than m, the fluidity of the carrier is low and the rubbing force of the electrostatic image carrier in the developing area becomes excessive,
The surface of the electrostatic charge image carrier is scratched, and the resulting shavings are collected by the cleaning device and returned to the toner replenishing device or the developing device to be mixed with the developer in the developing device. Since the toner is developed together with the toner, white spots (white spots) occur on the solid portion. On the other hand, when it exceeds 80 μm, the surface area of the entire carrier particles per unit weight is small, so that the toner carrying ability to the developing region becomes small and, as a result, the image density tends to be lowered.

The particle size distribution and volume average particle size of the carrier are measured by a laser diffraction particle size distribution measuring device HELOS.
(Manufactured by JEOL Ltd.).

Regarding the method for producing the carrier, for example, in the case of a resin-coated carrier, it is produced by a conventionally known method such as spray coating or dry coating.

<Toner Used in the Present Invention> The toner used in the present invention is an arbitrary toner known per se, which has a sensible property, a coloring property and a fixing property, and contains a colorant and other components in the binder resin. It contains the property improving agent of. As the binder resin, conventionally known ones such as styrene-acrylic resin, polyester resin, epoxy resin, polyvinyl acetal resin, and phenol resin can be used.

As the colorant used in the present invention, carbon black, nigrosine dye (CI No.50415B), aniline blue (CI No.50405), calco oil blue (CI
No.azoic Blue3), chrome yellow (CINo.14090),
Ultramarine Blue (CINo.77103), DuPont Oil Red (CINo.26105), Quinoline Yellow (CIN)
o.47005), methylene blue chloride (CI No.5201
5), Phthalocyanine Blue (CINo.74160), Malachite Green Oxalate (CINo.42000), Lamp Black (CINo.77266), Rose Bengal (CINo.454)
35), mixtures thereof, and the like.
The colorant is preferably contained in a sufficient amount so that a visible image having a sufficient density is formed, and is usually preferably contained in an amount of 1 to 20% by weight based on the binder resin. or,
In the case of the one-component magnetic developer containing magnetite or ferrite magnetic particles, these can also serve as a colorant.

In the toner used in the present invention, a property improving agent other than the above may be used. As this property improving agent, for example, an offset preventing agent such as a low molecular weight olefin polymer or copolymer such as polyethylene or polypropylene, alkylenebisfatty acid amides, fatty acid alcohol esters or the like can be added. These offset preventing agents may be used alone or in combination of two or more. Further, the use ratio thereof is preferably 1 to 20% by weight with respect to the binder resin.

Further, oil-soluble dyes such as nigrosine base (CI50415), oil black (CI20150) and spirone black, quaternary salt compounds containing a nitrogen atom such as pyridinium salt, triphenylmethane and ammonium salt, and any other The charge control agent may be added.

This toner can be obtained by a conventionally known production method, and the volume average particle diameter of the colored particles is 20 μm or less,
Particularly, those having a thickness of 6 to 10 μm are preferable.

<Other Additives> As the fluidizing agent, conventionally known inorganic fine particles and others can be used.

As the inorganic fine particles, for example, silica,
Examples thereof include fine particles of metal oxides such as titania, alumina, calcium oxide, magnesium oxide, barium oxide and beryllium oxide. The fine particles of these metal oxides may be hydrophobized.

[0071]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 100 parts by weight of polyester obtained by condensation polymerization of neopentyl glycol, ethylene glycol, terephthalic acid and trimellitic acid, 8 parts by weight of carbon black, 2 parts by weight of carnauba wax and 2 parts by weight of amide wax were added. Colored fine particles of 8 μm were manufactured through the usual mixing, kneading, pulverizing and classifying steps.

Next, the moisture content was changed to 74 pp with a dryer at 50 ° C.
Zinc stearate particles (average particle size 7 μm) controlled to m, hydrophobic silica and hydrophobic titania were added to the colored fine particles in an amount of 0.05% by weight, 0.6% by weight and 0.8% by weight, respectively.
It was mixed at a ratio of wt% (mixing environment temperature 25 ℃ relative humidity
55%).

42 parts by weight of this toner and 758 parts by weight of an acrylic resin-coated carrier (volume average particle size 60 μm) were mixed in an environment of a temperature of 21 ° C. and a relative humidity of 49% to obtain a developer having a charge amount of −25 μC / g.

This developer was modified into the following U-BI.
Put into X4045 machine (manufactured by Konica Co., Ltd.) and temperature is 20 ° C.
A 50 mm x 20 mm solid image was output in a 0% environment.

Photoreceptor: 0.3 μm of alcohol-soluble nylon is coated on an aluminum tube which is a conductive substrate, and then 0.3 μm of a polyvinyl butyral layer (charge generation layer) containing Y-type titanyl phthalocyanine is further coated. A BPZ type polycarbonate layer (charge transport layer) containing a styryl compound was applied thereon with a thickness of 24 μm. Negatively charged organic photoconductor for semiconductor laser A heater of 100W is installed inside the photoconductor and the heater is turned on while the machine is operating. Exposure: Semiconductor laser development: Contact reversal development Non-exposed area potential: -750V Exposure area potential: -50V Development bias potential: -600V Photoconductor-Development sleeve gap: 500μm Development sleeve peripheral speed / photoconductor peripheral speed ratio: 1.7 Blade material: Urethane rubber Cleaning blade linear pressure: 12g / cm Cleaning blade contact angle: 18 ° Recycle from cleaning unit to developer A pipe is installed, and the fatty acid metal salt and the recovered toner are simultaneously recycled through this pipe. A cloth bag containing silica gel was installed in the toner replenishment unit, and the periphery of the solid part of the output image was observed. A good image was obtained.

Example 2 The polyester of Example 1 was changed to a polyester obtained by polycondensing bisphenol A propylene oxide adduct, bisphenol A ethylene oxide adduct, terephthalic acid and trimellitic acid, and the volume of colored fine particles was changed. The average particle size was 9.3 μm. The water content of zinc stearate was set to 90 ppm in a dryer at 50 ° C. The charge amount was set to −20 μC / g by adding 0.4 wt% of hydrophobic silica, 0.6 wt% of hydrophobic titania and 0.03 wt% of aluminum stearate.

Photosensitive member-developing sleeve gap: 600 μm Developing sleeve peripheral speed / photosensitive member peripheral speed ratio: 1.9 Cleaning blade linear pressure: 8 g / cm Cleaning blade contact angle: The same as Example 1 except for the condition of 21 ° did.

When the periphery of the solid portion of the output image was observed, a good image without "tip fringe" was obtained.

Example 3 The polyester of Example 1 was changed to a styrene / butyl acrylate (= 80/20) copolymer, the carnauba wax was changed to a low molecular weight polypropylene, and the particle size of the colored fine particles was changed to 6
μm.

Water content is 26 ppm after drying at 80 ° C. Addition amount is 0.0
8% by weight, the charge amount of the developer is -15 μC / g.

Photosensitive member-developing sleeve gap: 500 μm Developing sleeve peripheral speed / photosensitive member peripheral speed ratio: 1.5 Cleaning blade linear pressure: 16 g / cm Cleaning blade contact angle: The same as Example 1 except for the condition of 20 ° did.

When the periphery of the solid portion of the output image was observed, a good image without "tip fringe" was obtained.

Example 4 In Example 3, zinc stearate was changed to lithium stearate, water content was dried at 80 ° C. and 48 ppm, and the coating resin was changed to methyl methacrylate / styrene (= 60/40) to obtain a developer. The charge amount of -12 μC / g was set.

Photosensitive member-developing sleeve gap: 800 μm Developing sleeve peripheral speed / photosensitive member peripheral speed ratio: 1.3 Cleaning blade linear pressure: 18 g / cm Cleaning blade contact angle: 19 ° Same as Example 1 except for the conditions did.

When the periphery of the solid portion of the output image was observed, a good image without "tip fringe" was obtained.

Comparative Example 1 The same test as in Example 1 was carried out except that aluminum stearate was dried at 90 ° C. for 24 hours and the water content was controlled to 1800 ppm.

The "tip fringe" was severe, and the image quality of the solid portion was not good.

Comparative Example 2 The same as Comparative Example 1 was used except that the water content was controlled to 600 ppm, but only the same results as in Comparative Example 1 were obtained.

Comparative Example 3 In Example 4, lithium stearate was added at 80 ° C. and 76 cmHg 24.
The product was dried under reduced pressure for 8 hours and the water content was adjusted to 8 ppm, and the output was adjusted to 0.2% by weight.

A large number of streaks corresponding to the peripheral method of the photoconductor are generated in the solid part. Since the water content is not too small, it can be expected that the resistance of lithium stearate is deteriorated and coating unevenness occurs.

[0092]

According to the present invention, a phenomenon "tip fringe" occurs in a system in which a fatty acid metal salt is applied to an organic photoreceptor in a reversal development system, in which toner is developed with a certain gap at the tip of an image. I have found a means to control

[Brief description of drawings]

FIG. 1 is a diagram illustrating a copying machine to which the present invention is applied.

FIG. 2 is a diagram illustrating a toner recycling system used in the present invention.

FIG. 3 is a diagram illustrating a toner recycling system used in the present invention.

[Explanation of symbols]

 12 Developing Device 13 Developer Carrier (Developing Sleeve) 14 Electrostatic Image Carrier (Photoconductor) 15 Cleaning Device 16 Toner Conveying Screw 1 17 Toner Conveying Screw 2 20 Toner Supply Box

Claims (2)

[Claims] 1. An image forming method of forming an electrostatic latent image on an organic photoreceptor and reversal developing the latent image using a developer, wherein a fatty acid metal salt having a water content of 10 to 500 ppm is formed on the photoreceptor. A reversal image forming method comprising: a supply unit and a unit for recycling at least a part of the supplied fatty acid metal salt to a developing unit. 2. A digital latent image is formed on an organic photoconductor,
In an image forming method in which the latent image is subjected to reversal development using a developer and then the toner not transferred to the transfer body is recycled to the developing unit, at least a water content of 10 to 500 p
A developer containing a fatty acid metal salt of pm.