JPH11133656A - Toner used in non-magnetic contact one-component type developing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent toner from being welded on a toner thin layer forming blade when the toner thin layer forming blade made of silicone rubber is used while it is properly worn within the guaranteed number of copies and further to form a uniform toner thin layer on a developing roller by specifying the roundness of the toner. SOLUTION: The toner whose roundness is larger than 0.94 is used. Thus, the working part tip 103 of the blade 101 is properly worn so as to eliminate the welding of the toner on the tip 103, and the deformation of the tip 103 caused by excessive wear is prevented and the toner thin layer is normally and smoothly formed. It is proper to set the hardness (JIS K 6301(A type)) of the silicone rubber at the tip 103 within 75 to 85 deg.. When the hardness is lower than the set one, the degree of the deformation caused by the wear is large and the normal toner thin layer is hardly formed. On the other hand, when the hardness exceeds the range, shaving amount is so small that a black stripe or a white stripe is caused by the welding of the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used in a non-magnetic contact one-component developing system, and more particularly to an image forming apparatus such as a laser printer, a facsimile, a digital copy and the like. It is possible to eliminate the fusion of the toner to the toner thin layer forming blade, prevent the occurrence of white streaks and black streaks on the image, and to properly form the toner thin layer by appropriately abrading the blade. Regarding possible toner.

[0002]

2. Description of the Related Art In image formation using electrophotography, an electrostatic latent image is formed on a photosensitive drum, the electrostatic latent image is developed with toner to make a visible image, and the toner image is transferred to a transfer paper. Then, a fixing method is adopted.

[0003] The developing system used for electrophotography includes a two-component magnetic developing system using a mixture of a toner and a magnetic carrier, a one-component magnetic developing system using a one-component toner containing magnetic powder, and a non-magnetic one-system. A non-magnetic one-component developing method using a component toner is known.
The non-magnetic one-component contact developing method is the most excellent in terms of miniaturization, cost, and simplicity of operation of the developing device.

In a non-magnetic contact one-component developing system, a one-component toner is supplied from a sub-roller to a developing roller, and the thickness of the toner layer is regulated by a thin toner layer forming blade. Developing is performed by contacting the substrate.

In the non-magnetic contact one-component developing system, the charge is applied to the toner mainly by the contact between the developing roller and the toner thin layer forming blade. A conductive material made of metal (such as sus) is used for the toner thin layer forming blade, and a voltage is applied to the blade.

Japanese Patent Application Laid-Open No. Hei 9-197710 discloses a latent image forming member for forming a latent image, and a toner layer formed on the surface of the latent image forming member by rotating while being pressed against the latent image forming member. A latent image is developed by a developing device having a toner layer carrier for developing the latent image to be developed, a toner supply member for supplying toner to the toner layer carrier, and a supply auxiliary member in contact with or close to the supply member. In developing, when the area of a toner projected image is A and the area of a circle whose peripheral length is L is AL,
A developing method using a pulverized non-magnetic one-component toner in which the average circularity (A / AL) of the toner is 0.94 or less is described.

[0007]

When a metallic conductive material (such as sus) is used for the toner thin layer forming blade, the toner is fused to the toner thin layer forming blade as printing is repeated, and this fusion is performed. There is a problem that a thin toner layer is not formed in a portion and black streaks or white streaks are generated on an image. Therefore, there is a problem that normal image formation cannot be maintained within the guaranteed number of prints. This tendency was particularly remarkable in operation under high temperature and high humidity. As a solution, the toner thin layer forming blade can be used while being worn appropriately within the guaranteed number of sheets, so that the fusion of the toner to the toner thin layer forming blade can be prevented, and the uniform toner thin layer can be formed on the developing roller. There are methods that allow formation. In order to prevent the toner from being fused to the toner thin layer forming blade, it is necessary to use the blade while appropriately abrading the tip of the working portion that comes into contact with the toner. For this purpose, it is advantageous to form the tip of the working portion of the blade with abradable rubber, especially silicone rubber. This is because rubber is excellent in wear properties. However, when a normal pulverized toner is used for a blade made of silicone rubber at the tip of the working part, the blade tends to wear significantly, and the tip of the working part is considerably deformed from its initial shape, and is within the guaranteed life of the developing unit. However, it is difficult to form a thin toner layer on the surface of the developing roller normally.

Accordingly, it is an object of the present invention to provide a non-magnetic contact one-component developing system in which a toner thin layer forming blade made of silicone rubber is used within a guaranteed number of sheets while being appropriately worn, thereby forming a toner thin layer. It is an object of the present invention to provide a one-component toner which can prevent fusion of toner to a blade and can form a uniform thin toner layer on a developing roller.

[0009]

According to the present invention, there is provided a toner for use in a non-magnetic contact one-component developing system using a silicone resin for a toner thin layer forming blade, wherein the circularity is greater than 0.94. A toner is provided. Hardness of silicone resin blade used for thin toner layer forming blade (JIS K6301 (A type))
Is preferably in the range of 75 to 85 degrees.

[0010]

DETAILED DESCRIPTION OF THE INVENTION

[Operation] In the present invention, the circularity (C) is defined as follows, assuming that the area of a toner projected image is A and the area of a circle whose peripheral length is L is AL, as is generally used. It means a value represented by the formula C = A / AL.

The present inventors have used a blade having a tip of an action portion made of silicone rubber as a toner thin layer forming blade in a non-magnetic contact one-component developing system, and a circular one as a one-component non-magnetic toner. Degree (C)
Is larger than 0.94, the tip of the working portion is appropriately worn so that the fusion of the toner to the tip of the working portion of the blade can be eliminated, and the deformation of the tip of the working portion due to excessive wear is reduced. It has been found that the formation of a thin toner layer is prevented normally and smoothly.

Referring to FIG. 1 for explaining the wear of the tip of the working portion of the blade, in FIG.
Is a metal plate 102 acting as a pressing spring.
And a working rubber tip 103 made of silicone rubber provided at the tip of the metal plate 102. In the initial stage (A) of the specific example shown in FIG. 1, the working portion tip 103 has a semicircular cross section, and generally has a height in the range of 1.2 to 3.0 mm.

The hardness (JIS K 6301 (A type)) of the silicone rubber at the tip 103 of the working portion is 75 to 75%.
It is appropriate that the angle is within the range of 85 degrees. When the hardness is less than the above range, the degree of abrasion deformation tends to increase, and it becomes difficult to form a normal thin toner layer. As a result, black streaks and white streaks occur due to fusion of the toner (see Table 2 in Examples described later).

It will be understood that, after printing (B), the height of the working portion tip 103 of the blade is reduced by the shaving amount d, and the semicircular structure of the working portion tip is deformed by wear. .

Table 1 in the examples described below shows the relationship between the circularity (C) of the toner used and the shaving amount d (mm) after running 3000 sheets for a blade made of silicone rubber having a hardness of 80 degrees at the tip of the working portion. The relationship is shown. From Table 1, it is clear that the use of toner having a circularity (C) of more than 0.94 is critical in reducing the amount of blade scraping and maintaining the blade in an appropriate range.

Although the tip of the silicone rubber acting portion of the blade for forming a thin toner layer used in the present invention has been described as having a semicircular shape, the present invention is not limited to this.
It should be understood that any curved cross-section, such as hyperbolic, may be used.

[Toner] The toner used in the present invention has a circularity of more than 0.94, particularly 0.95 or more. Unlike the irregular toner obtained by the pulverization method, this toner has a polymerization method, Spherical toner produced by spheroidization of amorphous toner is suitable.

The spherical toner is composed of a fixing resin component, a colorant, a high molecular weight or low molecular weight charge control agent,
It contains a release agent or the like, and preferably has a median diameter of 1 to 30 μm, particularly 5 to 25 μm, and D25 / D
Monodisperse particles having a degree of dispersion of a particle size represented by 75 of 2.0 or less, particularly 1.8 or less, or particles close thereto. In the present specification, D25 and D75 represent particle diameters corresponding to 25% and 75% of the total volume of the toner particles.

The polymerization spherical toner is obtained by subjecting a toner-forming composition containing at least a radical polymerization initiator, a vinyl monomer which can be a fixing resin, and a colorant to suspension polymerization in an aqueous medium. .

As long as the degree of circularity is within the above range, spherical toners obtained by other methods can of course be used. For example, an amorphous toner obtained by kneading, pulverizing and classifying a resin composition for forming a toner can be used in a hot air stream. Molten, spheroidized toner, or a melt of the toner forming resin composition is sprayed into a hot atmosphere,
Spherically granulated toners are also used for the purpose of the present invention. Hereinafter, a suitable polymerization method toner will be described.

The vinyl monomer capable of forming the fixing resin is water-insoluble and can form a thermoplastic resin having a fixing property and an electric detecting property. Examples thereof include, but are not limited to, vinyl aromatic monomers, acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, and monoolefin monomers.

As the vinyl aromatic monomer, the following formula (1)

Embedded image In the formula, R ₁ is a hydrogen atom, a lower alkyl group or a halogen atom, R ₂ is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, a nitro group, or a vinyl group, and φ is a phenylene group. Of vinyl aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o-, m-, p-chlorostyrene, p-ethylstyrene and divinylbenzene alone or in combination of two or more. Can be mentioned.

As the acrylic monomer, the following formula (2)

Embedded image In the formula, R ₃ is a hydrogen atom or a lower alkyl group, and R ₄ is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group, or a vinyl ester group. Acrylic monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, methacrylic acid-2
-Ethylhexyl, β-hydroxyacrylate,
γ-hydroxypropyl acrylate, δ-hydroxybutyl acrylate, β-hydroxyethyl methacrylate,
Examples include ethylene glycol dimethacrylate and tetraethylene glycol dimethacrylate.

Other monomers include vinyl esters such as vinyl formate, vinyl acetate, and vinyl propionate: vinyl ethers such as vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether and the like: diolefins, especially butadiene , Isoprene, chloroprene and the like: monoolefins, particularly ethylene, propylene, isobutylene, butene-1, pentene-1, 4-methylpentene-1 and the like. Suitable monomers are styrene monomers, acrylic monomers, styrene-acryl monomers, and the like.

As the colorant for the toner, an inorganic or organic pigment or dye is used, and suitable examples thereof are as follows. The colorant is preferably used in an amount of 3 to 20% by weight per resin in the toner. Black pigments Carbon black, acetylene black, lamp black, aniline black. Yellow pigment Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hanser yellow G,
Hanser Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake. Orange pigment Red lead graphite, molybdenum orange, permanent orange GTR, pyrazolo orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK. Red pigment Bengala, cadmium red, lead red, cadmium mercury sulfide, permanent red 4R, lithol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B. Purple pigment Manganese purple, fast violet B, methyl violet lake. Blue pigment Navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, indanthrene blue B
C. Green pigment chrome green, chromium oxide, pigment green B,
Malachite Green Lake, Fanal Yellow Green G. White pigment Zinc white, titanium oxide, antimony white, zinc sulfide. Extender barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

As the radical polymerization initiator, a radical polymerization initiator known per se, for example, an azo compound-based, hydroperoxide-based, peroxide-based, peracid-type initiator or redox-based initiator is used. Suitable examples of the initiator include, but are not limited to, the following. 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-cyclopropylpropionitrile), 2,2'-azobis (4-
Methoxy-2,4-dimethylvaleronitrile), 1,1′-azobis (1-cyclohexanecarbonitrile), benzoyl peroxide, (1-phenylethyl) azodiphenylmethane.

The toner forming composition for forming the spherical toner may contain a toner auxiliary known per se.
Examples of the toner auxiliary include a charge control agent and a release agent.

As the release agent, various waxes, polypropylene wax, polyethylene wax, acid-modified products thereof and the like are used, and these can be contained in the toner forming composition in the size of emulsion particles.

As the charge controlling agent, those known per se, for example, oil-soluble dyes such as nigrosine base (CI 5045), oil black (CI 26150) and spiron black,
In addition to a metal salt of naphthenic acid, a fatty acid metal soap, a metal-containing complex dye, and the like, a water-soluble monomer having a charge controllable functional group copolymerizable with the vinyl monomer may be used. Examples of such a monomer include a sulfonic acid, a phosphoric acid, a carboxylic acid type anionic group, and a cationic group such as a primary-, secondary- or tertiary-amino group and a quaternary animonium group. Radical polymerizable monomers having an electrolytic group of
A suitable example is as follows.

Styrenesulfonic acid, sodium styrenesulfonate, 2-acrylamide 2-methylpropanesulfonic acid, 2-acid phosphooxypropyl methacrylate, 2-acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxypropyl methacrylate, acrylic Acid, methacrylic acid, fumaric acid, crotonic acid, tetrahydroterephthalic acid, itaconic acid, aminostyrene, aminoethyl methacrylate, aminopropyl acrylate, diethylaminopropyl acrylate, γ-N- (N ′, N′-diethylaminoethyl) aminopropyl methacrylate , Trimethyl ammonium propyl methacrylate.

Further, electrolysis of the above-mentioned sulfonic acid, phosphoric acid, carboxylic acid type anionic groups, or cationic groups such as primary-, secondary- or tertiary-amino groups and quaternary animonium groups. It is also possible to introduce a charge control group at the polymer terminal by using a radical initiator having a functional group.

In producing a polymerization toner, a toner-forming composition containing a vinyl monomer or the like is suspended in water. In this case, the concentration of the composition is generally between 1 and 50.
%, Especially 5 to 30% by weight, the size of the suspended particles is generally 1 to 30 μm, in particular 5 to 25 μm.
It is appropriate to adjust to m.

If necessary, a dispersion stabilizer can be used to stabilize the suspension state of the toner-forming composition. Examples of such a dispersion stabilizer include polymers soluble in a medium such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polyacrylamide, polyethylene oxide, poly (hydroxystearic acid-g-methyl methacrylate-CO). A (methacrylic acid) copolymer, a nonionic or ionic surfactant or an inorganic powder such as calcium phosphate is appropriately used. The dispersion stabilizer is present in the system in an amount of 0.1 to 10% by weight, especially
It is preferably added in an amount of 0.5 to 5% by weight.

The amount of the initiator in the toner-forming composition is from 0.3 to 30% by weight, especially from 0.1 to 30% by weight, based on the monomer.
The content is preferably 5 to 10% by weight.

In the polymerization, the reaction system is replaced with an inert gas such as nitrogen, and the polymerization is carried out at a temperature of 40 to 100 ° C., particularly 50 to 90 ° C. while maintaining the above-mentioned suspension state. Of course, mild stirring can be performed to homogenize the reaction system. Since the polymerization product after the reaction is obtained in the form of granules having the above-mentioned particle size range, the resulting particles are filtered, washed with water or a suitable solvent if necessary, and dried to obtain toner particles.

It is effective to externally add a fluidity improver (surface treating agent) to the toner particles in order to improve the fluidity of the particles. That is, by spraying a fluidity improver (surface treatment agent) such as carbon black, hydrophobic amorphous silica, hydrophobic fine alumina powder, fine titanium oxide, and fine spherical resin,
The final toner is used. The flow improver (surface treatment agent) is preferably used in an amount of 0.1 to 3.0% by weight per toner.

In order to improve the flowability, heat resistance and offset resistance of the polymerized toner, the weight average molecular weight is
Generally, 10,000 to 150,000, preferably 10,000 to 100,000 is good.

[Non-Magnetic Contact One-Component Developing System] FIG. 2 shows an example in which the non-magnetic contact one-component developing system according to the present invention is applied to a printer 2. The printer 2 includes an airframe housing 20. A main body 21 having a box shape whose upper front portion is open at least, and a cover 23 pivotally mounted on an upper portion of the main body 21 by a shaft 22 are included. The process unit 4 is disposed inside the machine housing 20.

The process unit 4 includes a photosensitive unit 4
The developing device unit 50 is swingably provided on the photoreceptor unit 40 via the support shaft 5.

The photoreceptor unit 40 rotatably supports a photoreceptor drum 42, and a charging mechanism 43 is provided around the photoreceptor drum 42.
And a foreign matter collecting brush 44.

The developing device unit 50 has a developing housing 51, and includes a developing roller 53 housed in the housing and a sub-roller 54 which comes into contact with the developing roller 53 and supplies toner thereto. Below the developing roller 53, there is provided a blade 56 which regulates the thickness of the toner layer on the developing roller and also serves to charge the toner so as to be in contact therewith. Below the sub-roller 54, at a small interval, is the bottom 57 of the developing housing. In addition, a stirring paddle 55 for stirring the one-component toner is provided inside the developing housing 51 in the vicinity of the sub-roller 54. Since the sub-roller 54 and the developing roller 53 are in contact with each other and the developing roller 53 and the photosensitive drum 42 are in contact with each other by a trail (a forward direction at a contact portion), and the transfer paper is supplied in a one-pass face-down state. The photosensitive drum 42 rotates clockwise, the developing roller 53 rotates counterclockwise, and the sub roller 54 rotates clockwise.

The photosensitive unit 40 and the developing unit 5
A tension spring 52 is provided between the developing roller 53 and the developing roller 53 so as to press the developing roller 53 against the photosensitive drum 42. In this press-contact state, a passage 41 for image exposure is formed diagonally below the photosensitive drum 42.

A laser unit 24 is housed inside the housing body 21 of the machine housing. Laser light output from this unit 24 is guided to the photosensitive drum 42 through the exposure passage 41. .

Further, a paper feed tray 28 and a paper discharge tray 27 are provided in the body housing 20, and between them,
The pre-transfer guide plate 45, the transfer roller 31, which is opposed to and close to the photosensitive drum, the post-transfer guide plate 46, the fixing roller 25, and the discharge roller 26 are provided in this order. At the end of the paper feed tray 28, a paper feed roller 2 driven during printing is provided.
9 and a friction pad 30 are provided so that paper can be fed one by one.

The upper portion 452 of the pre-transfer guide plate 45, the transfer roller 31, the upper portion of the post-transfer guide plate 46, the upper portion of the fixing roller 25, and the upper portion of the discharge roller 26 are provided on the cover 23. On the other hand, the lower portion 451 of the pre-transfer guide plate 45, the lower portion of the post-transfer guide plate 46, the fixing roller 2
The lower portion of the transfer roller 5 and the lower portion of the discharge roller 26 are provided in the housing body 21 so that when the cover 23 is opened, all of these transfer paper passages are opened, so that a paper jam can be easily removed. .

As the photosensitive drum 42, any photosensitive drum having an electrophotographic photosensitive layer provided on a conductive metal drum can be used. From the viewpoint of preventing the generation of ozone, it is desirable to use a positively charged photoconductor. As the organic photoreceptor, a charge transporting agent, particularly a combination of a hole transporting agent and an electron transporting agent and a monodispersed layer type photoreceptor containing a charge generating agent in a resin medium or a charge transporting agent containing a charge transporting agent are used. The photoreceptor may be a laminate type photoreceptor having a layer and a charge generating layer containing a charge generating agent. In this case, the charge generating layer (CGL) and the charge transporting layer (CTL) are laminated in this order or the reverse order. Photoconductor may be used.

Examples of the charge generating agent include selenium, selenium-tellurium, amorphous silicon, pyrylium salt,
Azo pigments, disazo pigments, ancesthrone pigments,
Phthalocyanine-based pigments, indico-based pigments, selen-based pigments, toluidine-based pigments, pyrazoline-based pigments, perylene-based pigments, quinacridone-based pigments, and the like are exemplified, and one or more of them are mixed so as to have an absorption wavelength range in a desired region. Used.

Various resins can be used as the resin medium in which the charge generating agent is dispersed, such as a styrene polymer, an acrylic polymer, a styrene-acrylic polymer, an ethylene-vinyl acetate copolymer, polypropylene,
Olefin polymers such as ionomers, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester,
Alkyd resin, polyamide, polyurethane, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin,
Various polymers such as a phenol resin and a photocurable resin such as an epoxy acrylate can be exemplified. These binder resins may be used alone or in combination of two or more.
Suitable resins are styrenic polymers, acrylic polymers,
Styrene-acrylic polymer, polyester, alkyd resin, polycarbonate, polyarylate and the like.

As the charge transporting agent, any electron transporting or hole transporting agent known per se can be used alone or in combination of two or more, and is not limited thereto. -N-vinylcarbazole, phenanthrene, N-ethylcarbazole, 2,5-
Diphenyl-1,3,4-oxadiazole, 2,5-bis-
(4-diethylaminophenyl) -1,3,4-oxadiazole, bis-diethylaminophenyl-1,3,6-oxadiazole, 4,4′-bis (diethylamino) -2,2′-
Dimethyltriphenylmethane, 2,4,5-triaminophenylimidazole, 2,5-bis (4-diethylaminophenyl) -1,3,4-triazole, 1-phenyl-3-
(4-diethylaminostyryl) -5- (4-diethylaminophenyl) -2-pyrazoline, p-diethylaminobenzaldehyde- (diphenylhydrazone), tetra (m-methylphenyl) metaphenylenediamine, N,
Hole transporting agents such as N, N ', N'-tetraphenylbenzidine derivatives, N, N'-diphenyl-N, N'-dixylylbenzidines, 2-nitro-9-fluorenone, 2,7-dinitro -9-fluorenone, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2-nitrobenzothiophene, 2,4,8-trinitrothioxanthone, dinitroanthracene , Dinitroacridine, dinitroanthraquinone, 3,5-dimethyl-
Electron transporting agents such as 3 ′, 5′-di-t-butyldiphenoquinone and naphthoquinone derivatives are used.

In the monodispersed photoreceptor, the charge generating agent (CGM) is preferably contained in the photosensitive layer in an amount of 1 to 7% by weight, particularly 2 to 5% by weight, based on the solid content. The agent (CTM) is preferably contained in the photosensitive layer in an amount of 20 to 70% by weight, particularly 25 to 60% by weight, based on the solid content. Further, from the point of sensitivity and the wide range of applications that enable reversal development, it is preferable to use a combination of an electron transporting agent (ET) and a hole transporting agent (HT),
In this case, the weight ratio of ET: HT is 10: 1 to 1: 1.
It is most preferably in the range of 0, especially 1: 5 to 1: 1.

Generally, in the case of a small printer or FAX, the diameter of the photosensitive drum is about 10 to 60 mm.
The thickness of the photosensitive layer is about 10 to 40 μm.

As the charging mechanism 43, a corona charger such as a corotron or a scorotron is used. For the purpose of stably and uniformly charging the photosensitive layer, a scotron charger, that is, a corona wire, a shield And a charger provided with a grid provided at the opening of the shield on the photoconductor side is particularly suitable. In the apparatus shown in FIG. 2, the charging mechanism 43 is provided below the photoconductor drum 42, and is arranged so that the influence of the discharge product on the photoconductor is reduced as much as possible. The saturation charging potential of the photoconductor is generally 5
It is preferable to perform charging so as to be in the range of 00 to 2000 volts.

The developing roller 53 and the sub-roller 54 used in this image forming system are made of a conductive elastic (rubber) roller. The elastic roller is obtained by molding a composition obtained by mixing a conductive powder such as conductive carbon black or metal powder with an elastomer polymer such as urethane rubber or silicone rubber.

The volume resistance of the elastic developing roller 53 is:
Generally, it is preferably in the range of 10 ^{4 to} 10 ⁹ Ω · cm. If it is higher than the above range, it is difficult to apply a bias voltage. Tends to occur.

The hardness (Asker C hardness) of the elastic developing roller is preferably in the range of 60 to 85. When the hardness is higher than the above range, the toner layer is brought into uniform contact with the surface of the photoreceptor. When the temperature is lower than the above range, it is difficult to transmit a sufficient pressure contact force, and the developing roller is liable to be worn. Further, regarding the surface roughness of the developing roller, the ten-point average roughness RZ defined in JIS B 0601 is preferably in the range of 5.0 to 12.0 in terms of toner holding properties and developability.

As the sub-roller 54, a roller made of a conductive elastic material is used similarly to the elastic developing roller 53. However, it is suitable for the sub-roller to have a considerably smaller hardness than the developing roller. Generally, 75 to 95 degrees of Asker F hardness is appropriate.

The stirring paddle 55 stirs the one-component toner contained in the developing housing and supplies the one-component toner to the sub-roller. A stirring frame member provided on the rotating shaft is provided. And a flexible sheet member provided at the end of the frame member. The frame member and the sheet member are provided with a large number of holes so that the degree of stirring is not excessive. I am adjusting. The elastic sheet is formed of, for example, a PET film or the like, and is provided with elasticity so as to be in a curved state. Thus, the elastic sheet also acts to press the one-component toner against the sub-roller, and the one-component The supply of the system toner is performed smoothly.

In FIG. 3 showing the detailed structure of the thin layer forming blade 56, this blade 56 is a metal leaf spring 56.
The plate spring 561 is made of a thin steel plate having flexibility and elasticity, for example, a stainless steel plate or a spring steel plate having a thickness of about 0.1 to 0.2 mm. And has substantially the same longitudinal dimension. The leaf spring 561 includes the mounting portion 561a and the action portion mounting portion 5
61b. A front end 562 of an operating portion made of an insulating material such as silicone rubber is mounted on the surface of the operating portion attaching portion 561b (the side facing the developing roller 32) by means such as adhesion.

The mounting portion 561a of the leaf spring 561 is attached to the blade mounting portion 511a provided at the open end of the bottom wall 511 of the developing housing 51 on the side of the photoconductor unit 40, by the pressing plate 5a.
63 and attached. The blade mounting portion 511a, the mounting portion 561a of the leaf spring 561, and the pressing plate 563 are provided with a plurality of piss insertion holes at predetermined intervals in the longitudinal direction, and screws 565 are respectively inserted. , A screw portion 56 formed at the tip of the screw 565
The screw 5a is screwed into a female screw 563a formed in a piss insertion hole provided in the holding plate 563, so that it is tightened and fixed. The blade mounting portion 511a and the leaf spring 56
A seal member 566 made of a sponge material or the like is provided in a space formed by the first mounting portion 561a.

In this way, it is possible to always press the working portion tip 562 made of silicone rubber against the developing roller 53 with a constant pressing force. The one-component toner is given a charge of a fixed polarity by friction with the tip 562 of the operating portion and the developing roller 53.

As the silicone rubber constituting the tip of the action section, a silicone rubber having polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane or the like as a structural unit is used. These rubbers are used together with a rubber compounding agent such as a reinforcing agent such as extender (oil), carbon black and white carbon, and a filler. The hardness of the silicone rubber can be adjusted to the range specified in the present invention by adjusting the amount of the oil.

A bias voltage for enabling reversal development is applied to the developing roller 53. This bias potential has the same polarity as the charged potential of the unexposed portion of the photoreceptor and, in absolute value, is higher than the potential of the exposed portion and lower than the potential of the unexposed portion. It is preferable to make On the other hand, it is preferable to apply a bias potential having the same polarity as the developing bias potential and a high absolute value to the sub-roller 54 in order to smoothly supply the one-component toner to the developing roller. Generally, it is preferable to apply a voltage that is higher by 0 to 600 volts in absolute value than the developing bias voltage.

As shown in FIG. 2, the sub-roller 54 and the developing roller 53 contact downward by trailing, while the developing roller 53 and the photosensitive drum 42 contact upward by trailing. Is preferably in the range of 1.05 to 3.1, while the peripheral speed ratio of developing roller 53 / photosensitive drum 42 is suitably in the range of 1.2 to 3. When the peripheral speed ratio is smaller than the above range, the supply of the one-component toner becomes insufficient. On the other hand, when the peripheral speed ratio is larger than the above range, the abrasion tendency of the roller or the drum increases.

As the transfer roller 31, a transfer voltage is applied from the back of the transfer paper in a non-contact state with the photosensitive drum, and a conductive rubber roller is also used. This conductive rubber roller is similar to that of the developing roller, but its Asker C hardness is preferably 50 to 80.

The image formation in this non-magnetic one-component contact developing system is performed as follows.

1) Charging Step: The photosensitive layer of the photosensitive drum 42 is rotating in the direction of an arrow (clockwise) in FIG. 3, and is uniformly charged by a corona (for example, a positive corona) from the charging mechanism 43. . Generally, the surface potential of the photosensitive layer is set in the range of 500 to 2000 V in absolute value.

2) Image exposure step: In response to print data from a personal computer or word processor connected to the printer 2, a laser beam from the laser unit 24 is passed through the exposure passage 41 to the photosensitive drum 42.
The photosensitive layer is exposed to light to form an electrostatic latent image. As a result of performing image exposure using laser light, the potential of the portion corresponding to the light beam image of the photosensitive layer (that is, the portion irradiated with laser light) becomes 0 V to 300 V in absolute value, and the portion not irradiated with laser light (back The ground potential is kept at a dark decay potential from the main charging potential, and an electrostatic latent image is formed.

3) Developing step: The one-component toner is stirred by the stirring paddle 55, and is charged first by friction with the stirring paddle 55 or the wall of the developing housing 51. The charged one-component toner is supplied to the surface of the sub-roller 54 rotating in the direction of an arrow (clockwise) in FIG.
The developer is supported and transported to the developing roller 53 rotating counterclockwise, and is supplied to the developing roller 53. The thickness of the one-component toner layer on the surface of the developing roller 53 is regulated by the blade 56, and development is performed in contact with the photosensitive layer of the photosensitive drum 42. As described above, the final charging of the toner is performed by friction between the tip of the working portion of the blade and the developing roller. The one-component toner used for this development is
The photosensitive layer is charged to the same polarity as the potential of the unexposed portion of the photosensitive layer, so that the toner is adhered to the laser beam irradiated portion by reversal development.

4) Transfer process: The transfer paper stored in the paper feed tray 28 is supplied one by one between the transfer roller 31 and the photosensitive drum 42 by the paper feed roller 29 and the friction pad 30. The transfer of the toner image is performed in contact with the photosensitive drum 42 having the one-component toner image.

5) Fixing Step: The transfer paper on which the toner image has been transferred is supplied to a pair of fixing rollers 25, and the toner image is heated and fixed. The transfer paper on which the toner image has been fixed is discharged onto a tray 27 by a discharge roller 26.

6) Post-process: Foreign matter such as paper dust adhering on the photosensitive drum 42 is removed from the surface of the photosensitive drum by the foreign matter collecting brush 44, while toner remaining on the photosensitive drum surface is removed by the developing roller 53. Cleaning by the contact of

[0072]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the following examples.

Preparation of Toner Toner A: pulverized toner (no spheronization treatment) This toner uses styrene-acryl as a binder resin, is premixed using a Henschel mixer, and the mixture is extruded by a twin screw kneader. And melt kneading. Then, the kneaded material is pulverized and classified, and further subjected to an external addition treatment of 1 wt% of silica as a surface treating agent, whereby toner A is obtained.
The volume average particle diameter of the toner is a median value (D ₅₀ ) of 9.0.
μm. The circularity defined above of this toner is 0.3
It was 2. Toner B: pulverized toner (with spheroidization treatment) The toner is obtained by melting and spheroidizing the toner A in a hot air flow with a hot air treatment machine (surffusion system). The circularity of this toner was 0.75. Toner C: Polymerized toner This toner comprises a radical polymerization initiator, a styrene monomer,
It is obtained by subjecting a toner-forming composition containing an acrylic monomer, a colorant, and a synthetic wax to suspension polymerization in an aqueous medium, and externally adding 1.0 wt% of silica as a surface treatment agent. The volume average particle diameter of the toner is 9.0 μm (D ₅₀ ). The circularity of the toner was 0.95 as defined above.

The relationship between the circularity of the toner and the amount of blade shaving is described below.
Experiments shown A laser fax "TC-720" manufactured by Mita Kogyo Co., Ltd. was modified so as to adopt the configuration shown in FIGS. 2 and 3, and a verification experiment was conducted with the toner described above. The blade shaving amount from the initial stage after 3000 sheets (A4 length conversion) was measured. The results are as shown in Table 1. The amount of shaving when using toner A and toner B was 1.2 mm and 1.0 mm, respectively, and the amount of shaving of the blade was too large to form a normal toner thin layer ( That is, the thin layer becomes thicker), and the formed image also has high fog density and poor quality. On the other hand, in the case of the toner C, the blade was appropriately shaved and the occurrence of fusion of the toner was sufficiently prevented, and a normal toner thin layer could be formed.

The relationship between blade hardness and blade shaving amount is shown.
Experiment Using “TC-720” and toner C used in the above experiment,
By changing the blade hardness to the four types shown in Table 2, the blade shaving amount from the initial stage after 3000 prints (A4 length conversion) was measured. As a result, if the blade hardness is too low as 71 degrees, the amount of shaving of the blade is so large that a normal toner thin layer cannot be formed (that is, the thin layer becomes thick), and the formed image also has high fog density and poor quality. It became something. Conversely, if the blade hardness is too high, 90 degrees, the blade shaving amount is too small, and the same toner fusion as when using a sus or the like has occurred. On the other hand, the blade hardness 75
In the case of using the toner having a temperature of 85 ° and 85 °, the blade was appropriately shaved to sufficiently prevent the toner from fusing, and a normal thin toner layer could be formed. In addition,
The hardness of the blade used in the above experiment was JIS K 63
01 (A type).

[0076]

[Table 1] Note) The blade hardness is 80 degrees.

[0077]

[Table 2] Note) Use toner with circularity of 0.95 Note) Based on JIS K6301 (A type) blade hardness

[0078]

According to the present invention, in a non-magnetic contact one-component developing system using a silicone resin for a toner thin layer forming blade, a non-magnetic one-component toner having a circularity greater than 0.94 is used. It is possible to use the toner thin-layer forming blade while wearing it within the guaranteed number of sheets, while preventing toner fusion to the toner thin-layer forming blade and forming a uniform toner thin layer on the developing roller. It becomes possible. Therefore, according to the present invention, it is possible to form a print having excellent image quality without generation of white streaks or black streaks.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining the principle of the present invention.

FIG. 2 is a side view showing a simplified arrangement of an image forming apparatus to which the developing system of the present invention is applied. (A) is a side view of the entire apparatus, and (B) is an enlarged view near the exposure passage.

FIG. 3 is a perspective view showing how to attach a toner thin layer forming blade.

[Explanation of symbols]

 Reference Signs List 2 printer 4 process unit 5 support shaft 20 body housing 21 box-shaped main body 22 shaft 23 cover 24 laser unit 25 fixing roller 27 discharge tray 28 paper feed tray 29 paper feed roller 30 friction pad 31 transfer roller 40 photoconductor unit 41 exposure Passageway 42 Photoreceptor drum 43 Charging mechanism 44 Foreign matter collection brush 45 Pre-transfer guide plate 50 Developing device unit 51 Developing housing 52 Tension spring 53 Developing roller 54 Sub-roller 55 Stirring paddle 56 Blade 57 Bottom 101 Toner thin layer forming blade 102 Metal plate 103 Working part tip 511 Bottom wall 511a Blade mounting part 561 Metal leaf spring 561a Mounting part 561b Working part mounting part 562 Working part tip 563 Holding plate 563a Female screw 565 Screw 565a Screw

Claims (2)

[Claims] 1. A toner for use in a non-magnetic contact one-component developing system using a silicone resin for a thin toner layer forming blade, wherein the toner has a circularity of greater than 0.94. 2. Hardness of a silicone resin blade (JIS)
2. The toner according to claim 1, wherein the toner is used in a non-magnetic contact one-component developing system in which K 6301 (A type) is 75 to 85 degrees. 3.