JPH09127784A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method by which a stable carrying amt. is obtd. without influenced by the preceding image pattern or environments and an excellent image without fog or ghost can be stably formed with a stable image density for a long time even when the method is used for a color system. SOLUTION: This method includes a process to form a latent image on a latent image holding body, a process to form a toner image on the latent image holding body by using a developer on a developer carrying body, and a process to transfer the toner image to a transfer body. A cylindrical base body having a coating film of molybdenum oxide hydrate essentially comprising Mo, O and H formed on the body is used as the developer carrying body. The developer used is a non-magnetic one-component developer containing a binder resin, and a salicylic acid-based charge controlling agent containing elements selected from Al, Zn, B and Cr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming method using a non-magnetic one-component developer.

[0002]

2. Description of the Related Art In recent years, a dry developing method in an electrostatic copying system has begun to be used in the field of personal copying for individuals such as printers and facsimiles, and there is an increasing demand for downsizing and weight saving of the apparatus. ing. To cope with this, improvements in the image forming method have been made. The two-component developing method is the most widely used method, but the toner particles adhere to the surface of the carrier to deteriorate the developer and only the toner is consumed. Since it decreases, it is necessary to keep the mixing ratio with the carrier constant, which causes a drawback that the developing device becomes large.

On the other hand, the one-component developing system is becoming the mainstream of the developing system because it does not have the above-mentioned drawbacks and has advantages such as downsizing of the apparatus. As a one-component developing method, a magnetic one-component developing method using a toner containing magnetic powder has been proposed, but a clear color image cannot be obtained by the magnetic developing method in which a magnetic substance is contained in the toner. It has a drawback that it cannot meet the ever-increasing needs for colorization.

A non-magnetic one-component developing system has been proposed as a solution to these drawbacks. This development method
As shown in FIG. 1, the non-magnetic toner 15 in the developer hopper 13 is fed to the supply roller 12 adjacent to the developer carrying member 11.
Then, the toner is supplied onto the developer carrying member 11 by the agitator 17 and the toner layer is formed by the developer layer thickness regulating blade 14, and then the toner is attached to the electrostatic latent image of the electrostatic latent image holding member 16 to perform the development. It is a thing.

In the non-magnetic one-component developing system, compared with the magnetic toner system in which the magnetic substance is contained in the toner, the toner holding force by the developer carrying member is small, so that the toner of low charge is
It is likely to cause scattering and fog on the background portion, and more strict control of the charge amount is required. Generally, the charge characteristic of the toner is adjusted by a charge control agent. Japanese Unexamined Patent Publication No. 2-154277 proposes a method in which a chromium-containing monoazo dye and a salicylic acid metal salt are used in combination as a charge control agent. In this method, sufficient chargeability can be obtained even in the one-component development method in which chargeability is difficult to obtain, and an image without fog can be obtained, but the chromium-containing monoazo dye has colorability, and when used for a color toner, There is a drawback that the color characteristics of the toner are impaired.

Further, when the non-magnetic one-component developing system is applied to a full color system in particular, it is necessary to strictly control the density, and for that purpose, it is important to stabilize the toner conveyance amount. However, since the non-magnetic one-component developing method does not rely on the magnetic force to convey the toner to the developer carrier, the toner supply amount on the developer carrier (hereinafter, referred to as the convey amount) is the image pattern of the previous image. However, there is a problem in that a stable image cannot be obtained due to changes in the environment, the environment, and the like. In particular, a phenomenon in which an image density difference appears depending on the image pattern of the previous image is called ghost, and it is known that the ghost phenomenon is aggravated when the change in the carry amount due to the image pattern of the previous image is large.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the problems in the prior art.

That is, the first object of the present invention is to obtain an image having a stable carry amount which is not influenced by the preceding image pattern, environment, etc., has no ghost even when used in a color system, and has a stable image density for a long time. It is to provide a forming method.

A second object of the present invention is to provide an image forming method capable of preventing fog in the background portion and stains inside the machine due to toner scattering for a long period of time.

[0010]

Means for Solving the Problems The present inventors have found that Mo,
By combining a developer carrying member provided with a film made of a material containing H and O and a toner containing a salicylic acid metal complex containing Al, Zn, B or Cr,
The inventors have found that the image forming method has no background fogging, the image density is stable even when used in a color system, and there is no in-machine stain due to toner scattering, thus completing the present invention.

That is, according to the present invention, a step of forming a latent image on a latent image carrier, a step of forming a toner image on the latent image carrier using a developer on a developer carrier, the toner image In the image forming method having a step of transferring the
As the developer carrying member, one having a coating of molybdenum oxide hydrate containing Mo, O and H as main constituents on a cylindrical substrate is used, and as a developer, a binder resin, a colorant, and Al are used. A non-magnetic one-component developer containing a salicylic acid-based charge control agent containing an element selected from Zn, B, and Cr is used.

Although the mechanism in the present invention is not clear, a developer carrying member provided with a toner containing the above charge control agent and a film of molybdenum oxide hydrate containing Mo, O and H as main constituents. It is considered that, when combined with, the charge amount distribution becomes sharp, so that the toner in the low charge region is reduced, and as a result, a good image without toner scattering and no fog on the background portion can be obtained. Even when applied to a non-magnetic development method, the amount of conveyance is stable and the density of a color image is stable because the amount of charge is stable over time and the environment, and toner adheres to the developer carrier. It seems that there is no such thing.

[0013]

Embodiments of the present invention will be described below in detail. The image forming method of the present invention comprises the step of forming a latent image on a latent image holding member, and the electrostatic latent image on the latent image holding member by a developer layer thickness regulating member which is brought into pressure contact with a developer carrying member. The method has a step of forming a toner image with a developer layer-formed on a developer carrying member, and a step of transferring the toner image onto a transfer member. , O and H as main constituents, and a film of molybdenum oxide hydrate is provided.

The material of the cylindrical substrate of the developer carrying member used in the present invention may be aluminum, stainless steel or the like. For example, a cylindrical product obtained by extruding aluminum or the like is subjected to centerless polishing. Alundum # 600
Or a roughening treatment such as surface roughening by blasting with an amorphous brown alumina abrasive material A (JIS R6111-1987). In addition, this cylindrical substrate is provided with M
For the purpose of increasing the durability of a molybdenum oxide hydrate film containing o, O and H as main constituents, Z is applied to the surface of the film.
It is preferable to provide an undercoating film made of n, for example, an aluminum tube having a Zn undercoating film formed on its surface by chemical plating after the above-mentioned roughening treatment is preferred.

The above-mentioned cylindrical substrate is provided with a molybdenum oxide hydrate film containing Mo, O and H as main constituents (hereinafter referred to as "Mo-based film"). It can be formed by chemical conversion treatment using a solution containing molybdate. More specifically,
A treatment liquid containing molybdate ion (KoO ₄ ²⁻ ) is used to perform electrolytic treatment using a cylindrical substrate as a cathode to form a double salt colloidal film containing Mo, O and H as the main components on the cylindrical substrate. Then, the colloidal film is dried (hardened) in the drying step. The Mo-based film formed as described above is presumed to consist of molybdenum oxide hydrate containing Mo, O and H as main constituents, but its detailed structure is unknown.

The film thickness of the Mo-based film can be arbitrarily adjusted by changing the above processing time, but from the viewpoint of the effect of suppressing the development ghost, it is preferably 0.8 μm or more and 10 μm or less. , Especially from 2.5
The range is preferably 3.5 μm. Furthermore, Mo
The crack width of the system film can be controlled by adjusting the temperature in the drying process, but it is preferable to set the crack width to 0.3 μm or less because the effect of suppressing the development ghost can be improved. The surface roughness of the developer carrier is preferably such that Ra (μm) is 0.1 or more and 3.0 or less, more preferably 1.0 to 2.5, and even more preferably 1. It is in the range of 5 to 2.0. R
When a is smaller than 0.1, the amount of toner on the developer carrying member is insufficient, so that an appropriate density cannot be obtained, and Ra is 3.0.
If it is larger than the above range, poor charging of the toner may occur, causing fog. Therefore, the above range is preferable. The surface roughness of the developer carrying member can be adjusted by subjecting the cylindrical substrate to centerless polishing and glass bead or sandblast treatment.

The developer used in the present invention is a non-magnetic one-component developer, which is a metal salicylate containing a binder resin, a colorant, and an element selected from Al, Zn, B and Cr as a charge control agent. Contains a complex.

As the binder resin, known resins conventionally used for toners can be used. For example, 1
Alternatively, homopolymers and copolymers of two or more vinyl monomers can be used. Typical vinyl monomers include, for example, vinyl aromatic compounds such as styrene, p-chlorostyrene, and vinylnaphthalene, such as ethylene,
Ethylenically unsaturated monoolefins such as propylene, butylene, isobutylene, for example, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate,
Vinyl esters such as vinyl benzoate, vinyl butyrate, vinyl formate, vinyl stearate and vinyl caproate, for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, acrylic acid. n-octyl, 2-chloroethyl acrylate, phenyl acrylate, methyl-α-chloroacrylate, methyl methacrylate, ethyl methacrylate,
Ethylenic monocarboxylic acids such as butyl methacrylate and esters thereof, for example, acrylonitrile, methacrylonitrile, ethylenic monocarboxylic acid substitution products such as acrylamide, for example, dimethyl maleate, diethyl maleate, ethylene such as dibutyl maleate. Dicarboxylic acids and esters thereof, for example, vinyl methyl ketone, vinyl hexyl ketone, vinyl ketones such as methyl isopropenyl ketone, for example, vinyl methyl ether, vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether, for example, vinylidene chloride,
Examples thereof include vinylidene halides such as vinylidene chlorofluoride, and N-vinyl heterocyclic compounds such as N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone.

As the colorant, any known colorant can be used. In addition, pigments, dyes and other substances may be contained for the purpose of coloring, controlling electric resistance and the like. For example, carbon black, azine dyes such as nigrosine, chromium dyes such as chromium salicylate complex, polymeric acids such as copolymers containing maleic acid as a monomer component, quaternary ammonium salt, aniline blue, chrome yellow. , Ultramarine blue, methylene blue chloride, phthalocyanine blue, rhodamine 6G lake, etc. can be added, but when used in a color toner, it is desirable to select a material in the range that does not impair the color tone.

Furthermore, in order to make the offset resistance more complete, a release agent may be added. As the release agent, paraffins having 8 or more carbon atoms, polyolefins and the like are preferable, and for example, paraffin wax, paraffin latex, microcrystalline wax and the like, or polypropylene and the like can be used.

As the salicylic acid metal complex containing an element selected from Al, Zn, B and Cr, which is a charge control agent, compounds represented by the following chemical formulas and structural formulas are preferably used. The content of these charge control agents is set in the range of 0.1 to 6% by weight, preferably 0.5 to 5% by weight, and more preferably 1 to 4% by weight.

[0022]

Embedded image

In the present invention, for the purpose of improving the durability, fluidity or cleaning property of the toner, inorganic fine powder such as silica, organic fine powder such as fatty acid or its derivative and metal salt, fluorine resin fine powder. Etc. can be added.

The toner used in the present invention can be produced by any conventionally known method, but a pulverization method is particularly preferable. That is, it is preferable to obtain a toner particle by mixing a binder resin, a colorant, a charge control agent and other components, melting and kneading with a heat kneader, cooling, pulverizing and classifying.

[0025]

The present invention will be described below in detail with reference to examples. Example 1 Binder resin: Styrene-butyl acrylate copolymer 80 parts by weight (copolymerization ratio 80/20, weight average molecular weight Mw: 800,000) Copper phthalocyanine-based pigment 10 parts by weight Negatively chargeable charge control agent (ex. Charge control agent 1) 5 parts by weight The above materials were powder-mixed by a Henschel mixer, and the mixture was heat-kneaded by an extruder having a set temperature of 140 ° C. After cooling, coarse pulverization and fine pulverization, 50% volume particle diameter D50
8.6 μm was obtained. Further, the pulverized product was classified to obtain a classified product having D50 = 9.2 μm, 5 μm or less: 12%. To 100 parts by weight of the obtained toner classified product,
0.5 parts by weight of hydrophobic colloidal silica having a particle diameter of 16 nm was added and mixed by a Henschel mixer to obtain a toner.

The toner thus produced was evaluated by the following apparatus. FIG. 2 shows a cross-sectional structure of the developer carrying member used in the developing device of the embodiment. The developer carrier is
An undercoat film 22 and a Mo-based coating 23 are formed on a cylindrical substrate 21. Here, as the cylindrical substrate 21, an aluminum tube which has been subjected to centerless polishing and blasting with glass beads after drawing is used. A Zn film was adopted as the base film 22, and its formation was performed by electroless plating using an aqueous solution in which about 10 g of Zn and about 100 g of NaOH were dissolved in 1 liter of water. Mo
The system film 23 is formed by a treatment liquid containing a molybdate ion (MoO ₄ ²⁻ ) at the time of cathodic electroless treatment (trade name: 5C01).
1, manufactured by Nippon Surface Chemical Co., Ltd.) and subjected to electrolytic treatment using the aluminum tube as a cathode. The surface roughness of the obtained developer bearing member was Ra = 1.8 and the film thickness = 3.1.

As an apparatus, a printer (PCPR100
(0/4, manufactured by NEC Co., Ltd.) is changed to the developer carrier prepared by the above-mentioned procedure, and the toner carrier can be supplied without trouble even if there is no magnetic force. The supply roller of No. 1 was installed so as to be adjacent to the developer carrying member, and was modified so as to rotate in the opposite direction (against) with respect to the developer carrying member.

Using the above apparatus, evaluation was carried out under the following conditions. Development bias (AC) = 1.5 kVp-p (frequency 2.5
Square wave of kHz) Development bias (DC) =-200V VHigh = -400V, VLow = -50V Interval between latent image carrier / developer carrier = 200 μm Environmental temperature = 10 ° C., environmental humidity = 10% And solid image density (SAD) of the image after copying 5000 sheets, background fog (BK
G), ghost, and the amount of toner scattering in the developing machine after copying 5000 sheets and the amount of change in the carry amount.

Example 2 Binder resin: Polyester resin (condensation polymer containing fumaric acid and bisphenol A 85 parts by weight as a main component of propylene oxide adduct, weight average molecular weight Mw: 9,000, Tg = 65 ° C.) Copper Phthalocyanine pigment 10 parts by weight Negatively chargeable charge control agent (the above-mentioned charge control agent 2) 5 parts by weight The above materials were powder-mixed in the same manner as in Example 1, and heat kneaded,
Coarse pulverization and fine pulverization were performed to obtain a 50% volume particle diameter D50 of 10.
A pulverized product of 3 μm was obtained. Further classify this crushed product,
D50 = 11.0 μm, 5 μm or less: A 10% classified product was obtained. To 100 parts by weight of the obtained toner classified product, 0.4 parts by weight of hydrophobic colloidal silica having a particle diameter of 16 nm was added and mixed by a Henschel mixer to obtain a toner.
The obtained toner was evaluated in the same manner as in Example 1.

Example 3 Binder resin: Polyester resin (condensation polymer mainly composed of fumaric acid and 85 parts by weight of bisphenol A, a propylene oxide adduct, weight average molecular weight Mw: 9,000, Tg = 65 ° C.) Copper Phthalocyanine pigment 10 parts by weight Negatively chargeable charge control agent (Exemplified charge control agent 3) 5 parts by weight The above materials were powder-mixed in the same manner as in Example 1 and heat kneaded.
Coarse pulverization and fine pulverization give 50% volume particle diameter D50 of 8.5
A pulverized product of μm was obtained. Further classify this pulverized product, and
50 = 9.0 μm, 5 μm or less: 18% of a classified product was obtained.
Particle size 1 per 100 parts by weight of the obtained toner classified product
0.5 parts by weight of 6 nm hydrophobic colloidal silica was added and mixed by a Henschel mixer to obtain a toner. The obtained toner was evaluated in the same manner as in Example 1.

Example 4 Binder resin: Polyester resin (condensation polymer containing fumaric acid and bisphenol A 85 parts by weight as a main component of propylene oxide adduct, weight average molecular weight Mw: 9,000, Tg = 65 ° C.) Copper Phthalocyanine pigment 10 parts by weight Negatively chargeable charge control agent (the above-mentioned charge control agent 4) 5 parts by weight The above materials were powder-mixed in the same manner as in Example 1 and heat kneaded,
Coarse pulverization and fine pulverization are performed to obtain 50% volume particle diameter D50 of 7.6.
A pulverized product of μm was obtained. Further classify this pulverized product, and
50 = 8.0 μm, 5 μm or less: A 24% classified product was obtained.
Particle size 1 per 100 parts by weight of the obtained toner classified product
0.6 parts by weight of 6 nm hydrophobic colloidal silica was added and mixed by a Henschel mixer to obtain a toner. The obtained toner was evaluated in the same manner as in Example 1.

Comparative Example 1 Binder resin: Styrene-butyl acrylate copolymer 85 parts by weight (copolymerization ratio 80/20, weight average molecular weight Mw: 800,000) 10 parts by weight of carbon black (Regal 330, manufactured by Cabot Corporation) Negatively chargeable charge control agent (Cr-containing azo dye: TRH 5 parts by weight, manufactured by Hodogaya Chemical Co., Ltd.) The above materials were powder-mixed in the same manner as in Example 1, and heat kneaded.
Coarse crushing and fine crushing give 50% volume particle diameter D50 of 8.8
A pulverized product of μm was obtained. Further classify this pulverized product, and
50 = 9.3 μm, 5 μm or less: 13% of a classified product was obtained.
Particle size 1 per 100 parts by weight of the obtained toner classified product
0.5 parts by weight of 6 nm hydrophobic colloidal silica was added and mixed by a Henschel mixer to obtain a toner. The obtained toner was evaluated in the same manner as in Example 1.

Comparative Example 2 An aluminum tube (Ra that has been subjected only to centerless polishing)
= 0.3) was used as the developer carrying member, and the evaluation was performed in the same manner as in Example 1.

The evaluation results of Examples 1 to 4 and Comparative Examples 1 and 2 are summarized in Table 1 below. In the table, the solid image density (SAD) was measured by an X-rite densitometer, and the ghost was evaluated by the density difference between the non-image area and the image area.

[0035]

[Table 1] Note 1) BKG: Fog in the background area ○: Good, △: Slightly bad, but no problem in practical use,
×: Impractical in practical use Note 2) Ghost ○: Concentration difference less than 0.05, Δ: Concentration difference 0.05 to 0.1
Less than, ×: Density difference of 0.1 or more Note 3) Amount of change in carry amount: Difference between the carry amount in the initial stage (toner amount per area of the developer carrier) and the carry amount after copying 5000 sheets ◯: 1.0 g / less than m ² , Δ: 1.0 to 2.0 g / m ²
Less than, ×: 2.0 g / m ² or more Note 4) Toner scattering ◯: None, Δ: Slightly generated, but practically no problem, ×: Severe

[0036]

As described above, the image forming method of the present invention uses the developer carrier having the molybdenum oxide hydrate film containing Mo, O and H as the main constituents on the cylindrical substrate as described above. Binder resin, coloring agent, Al, Z
By using a non-magnetic one-component developer containing a salicylic acid type charge control agent containing an element selected from n, B and Cr, it is not affected by the preceding image pattern, environment, etc.
Even when applied to a non-magnetic one-component color development system, a stable toner conveyance amount can be obtained, and there is no contamination inside the machine due to toner scattering, and images with excellent image quality without fog or ghost on the background are stable and stable over a long period of time. Can be obtained at.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus for carrying out the present invention and a conventional image forming method.

FIG. 2 is a schematic sectional view of a developer carrying member used in the present invention.

[Explanation of symbols]

11 ... Developer carrier, 12 ... Supply roller, 13 ... Developer hopper, 14 ... Developer layer thickness regulating blade, 15 ... Nonmagnetic toner, 16 ... Electrostatic latent image carrier, 17 ... Agitator,
21 ... Cylindrical substrate, 22 ... Base film, 23 ... Mo-based film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hirono Okuno 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor Satoshi Torikoshi 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. ) Inventor Kotaro Yoshihara 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (1)

[Claims] 1. A process of forming a latent image on a latent image carrier, a process of forming a toner image on the latent image carrier using a developer on a developer carrier, and a process of forming the toner image on a transfer medium. In the image forming method having a step of transferring to, a developer carrying member having a molybdenum oxide hydrate film mainly composed of Mo, O and H on a cylindrical substrate is used as the developer carrying member.
Image forming using a non-magnetic one-component developer containing a binder resin, a colorant, and a salicylic acid-based charge control agent containing an element selected from Al, Zn, B, and Cr as the developer Method.