JP3352251B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method to which so-called electrophotography is applied, and more particularly, to a developing device which does not remove toner remaining on the surface of a photoreceptor after image formation with a cleaner. The present invention relates to an image forming method for collecting images and recycling them for image formation.

[0002]

2. Description of the Related Art Recently, in an image forming apparatus such as a laser beam printer, the surface of a photoreceptor after an image is formed from the viewpoint of further miniaturization of the apparatus, maintenance-free operation, environmental protection, and resource saving. Various image forming methods have been proposed in which a cleaner for removing residual toner is omitted, and the residual toner is collected by a developing device and reused for image formation (for example, JP-A-3-219275, JP-A-3-219275). 4
20987, JP-A-4-20988, etc.).

According to this method, the space for the cleaner can be omitted, so that the apparatus can be significantly reduced in size. Further, since almost no waste toner is generated every time an image is formed, maintenance-free operation of the apparatus is possible, and this is preferable for environmental protection. In addition, since previously discarded toner can be reused repeatedly,
The toner consumption is small, which is preferable from the viewpoint of resource saving.

[0004]

However, in the conventional image forming method, foreign matters other than the toner, which have been removed by the cleaner together with the toner, such as paper fiber fragments, talc powder, and sulphate band collectively referred to as paper powder. In the above-mentioned method, the powder and the like are collected in the developing device together with the toner and mixed into the toner, thereby deteriorating the image quality of the formed image,
It has also been found that various problems such as significantly shortening the life of the toner are caused.

That is, the particle size of the foreign matter mixed into the toner is much larger than that of the toner.
(Foreign particles such as paper dust are about 0.3 mm in contrast to about .mu.m.) Therefore, the formed image before fixing is disturbed or the non-image portion is stained. In addition, toner adheres to the periphery of the foreign matter, and a lump of toner is generated in the developing device, which is caught between a developing roller of the developing device and a toner charging blade pressed against the developing roller. There is a portion where the toner is not supplied to the developing roller, which causes image defects such as white stripes.

Further, the foreign matter destabilizes the charging characteristics of the toner, and causes image defects such as fogging of a non-image portion due to abnormally high charging, toner scattering due to abnormally low charging, and a decrease in image density. Further, there is also a problem that the life of the toner is significantly shortened due to the accumulation of foreign matter in the developing device.

In particular, recently, in the case of a system in which a photosensitive member and a toner cartridge are integrated as a developing unit, which is frequently used in, for example, a compact type laser beam printer or the like, the life of the toner is greatly reduced as described above. If the size is reduced, the replacement time of the developing unit is advanced, which is not preferable in terms of economy, resource saving, environmental protection, and the like.

In the apparatus disclosed in each of the above-mentioned publications, in order to facilitate the collection of the residual toner by the developing device, the conductive brush is brought into contact with the residual toner electrostatically adhered to the surface of the photoreceptor, thereby making the contact. Residual toner is loosened (memory removal), and there is a possibility that a very small amount of foreign matter can be removed from the photoreceptor surface by this brush.

However, if image formation is repeated and the amount of foreign matter increases, the brush alone cannot remove the foreign matter, and the removed foreign matter remains attached to the brush. Also, Japanese Patent Application Laid-Open No. Hei 4-267282
Japanese Patent Application Laid-Open Publication No. H11-146,086 discloses that another brush for capturing foreign matter is brought into contact with the surface of the photoreceptor before the memory of the toner is removed by the conductive brush, and the foreign matter is removed by the brush. . However, the removed foreign matter is still attached to the brush, so there is a limit to the amount of foreign matter that can be removed by the brush, and the foreign matter attached to the brush is
There is also a possibility that the toner adheres to the photoconductor. This requires frequent replacement or cleaning of the brush.

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device for recovering and reusing toner remaining on the surface of a photoreceptor after image transfer. An object of the present invention is to provide a novel image forming method which can be more reliably removed from a body surface.

[0011]

According to the image forming method of the present invention for solving the above-mentioned problems, a toner is brought into contact with an electrostatic latent image formed on the surface of a photoreceptor by a developing device. In the image forming method, the electrostatic latent image is visualized as a toner image, and after transferring the toner image to an object to be transferred, toner remaining on the surface of the photoreceptor is collected and reused by the developing device. An approximately spherical toner is used, and the toner image is transferred to paper and pressed against the surface of the photoreceptor.Spherical particles pass through, but irregular particles do not pass from the surface of the photoreceptor. It is characterized in that irregularly shaped foreign matter adhered to the surface of the photoreceptor together with the toner is selectively removed by an elastic blade to be removed.

According to the image forming method of the present invention having the above-described structure, in the normal image forming method, the elastic blade used for the cleaner for removing the residual toner and pressed against the surface of the photosensitive member has an irregular shape. Particles can be removed from the surface of the photoreceptor without passing through, but spherical particles have the property of passing through, and according to this method, the irregular shape adhered to the surface of the photoreceptor together with the toner Foreign matter can be selectively and reliably removed from the surface of the photoconductor.

The foreign matter removed from the surface of the photoreceptor is
Since the particles fall and accumulate in a collecting container or the like arranged below the blade, there is no possibility that the foreign matter once collected adheres to the surface of the photoconductor again, unlike the conventional brush-based removal. Moreover, the amount of foreign matter that can accumulate in the collection container or the like is several hundred times or thousands of times the amount that can be attached to the brush, so it is necessary to dispose of it frequently as in the case of conventional brush replacement and cleaning. Therefore, it is possible to further contribute to making the apparatus maintenance-free.

Hereinafter, the image forming method of the present invention will be described with reference to FIG. 1 showing an example of an apparatus for carrying out the method. As shown in the figure, this apparatus is a paper dust cleaner having a charging charger 2, a developing device 3, a transfer charger 4, a separation charger 5, and an elastic blade 61 around a photoreceptor 1 rotating in a direction indicated by an arrow in the drawing. 6 with the photoconductor 1
Are arranged in this order along the rotation direction of.

Although not shown, exposing means, a sheet conveying system, a fixing device, and the like are appropriately arranged around each of the above components. For example, when the apparatus is a laser beam printer or a facsimile, the exposing means is constituted by a semiconductor laser apparatus and a scanning / imaging optical system including a scanning member such as a polygon mirror.

The photoreceptor 1 is formed by forming a photoconductive single-layer or multi-layer photosensitive layer on the surface of a cylindrical conductive substrate such as an aluminum pipe. As the photosensitive layer, although not particularly limited, a so-called organic photosensitive layer in which a functional material such as a charge generating agent and a charge transporting agent is dispersed in a binder resin is preferably employed because of a large degree of freedom in functional design. Is done. Also, as the organic photosensitive layer, a so-called single-layer type organic photosensitive layer in which the functional material is dispersed in a single organic layer is preferably employed because the number of steps is small.

Each of charging, transferring and separating chargers 2,
Each of the conductive wires 4 and 5 is formed of a conductive wire stretched in the vicinity of the surface of the photoconductor 1 as in the conventional art. A voltage is applied between the wire and the photoconductor 1 to cause corona discharge.
Each charger performs the functions of charging, transferring, and separating. Each charger may be formed of a conductive roller or the like that is in contact with the surface of the photoconductor 1.

The developing device 3 includes a developing roller 31 that rotates at a peripheral speed different from the peripheral speed of the photoconductor 1 in a direction indicated by an arrow in the figure. A thin layer of toner formed around the developing roller 31 is removed. To visualize the electrostatic latent image on the surface of the photoreceptor 1 by so-called one-component contact development in which the electrostatic latent image on the surface is visualized as a toner image while being pressed against the surface of the photoreceptor 1 The developing roller 31 is provided in the developing device main body 30.
And a blade 32 for forming a thin layer of toner on the surface of the developing roller 31. Further, at least the surface of the developing roller 31 is formed of flexible urethane rubber or the like.

In the case of the one-component contact developing system, the toner remaining on the surface of the photoreceptor 1 is physically and electrostatically collected by the developing roller 31 in contact with the surface of the photoreceptor 1. Even when there is a large amount of residual toner on the surface of No. 1, the toner can be reliably collected, and there is no possibility that an afterimage (memory) of the previous image remains in the next formed image. However, in the present invention,
A magnetic brush formed by mixing toner with a magnetic carrier,
This does not exclude a so-called two-component contact development system in which the electrostatic latent image on the surface of the photoconductor 1 is visualized into a toner image by bringing the surface into contact with the surface of the photoconductor.

The contact developing method is a normal developing method (positive-positive method) in which a toner of opposite polarity is electrostatically adhered to a non-exposed portion having a high potential in an electrostatic latent image on the surface of the photosensitive member 1. And a reversal developing method (negative-positive method) in which a toner of the same polarity having a higher potential than the exposed part and a lower potential than the non-exposed part is electrostatically attached to the exposed part having a lower potential. In the latter case, the toner has a weaker electrostatic adhesion to the photoreceptor 1 and the residual toner is easily collected by the developing device 3. In a laser beam printer or a facsimile, it is more efficient to expose a character portion having a smaller area. Is
In consideration of the fact that the latter is more general, the reversal development method is more preferably adopted. However, the present invention does not exclude the former positive-positive developing method.

In any case, if the photosensitive member 1 is negatively charged, ozone which affects the environment and the photosensitive member is generated at the time of charging, so that the photosensitive member 1 is preferably of a positive charging type. Adopted. Therefore, in the case of the positive-positive developing method, a positively charged photosensitive member 1 and a negatively charged toner are used in combination, and in the case of the negative-positive reversal developing method, the positively charged photosensitive member 1 and a positively charged toner are used in combination. Is preferred.

The paper powder cleaner 6 includes the elastic blade 61
And a cleaner main body 60 also serving as a collection container for collecting foreign matter such as paper dust removed from the surface of the photoconductor 1 by the elastic blade 61. Elastic blade 61
Is a plate-like member made of an elastic member such as rubber, like a cleaning blade for removing residual toner in a conventional image forming method, and is pressed against the surface of the photoconductor 1 with a predetermined pressing force. .

As described above, the elastic blade 61 can remove irregular particles from the surface of the photoreceptor 1 without passing the particles, but has the property of allowing spherical particles to pass therethrough. Of the substantially spherical residual toner and irregular foreign matter such as paper dust mixed on the surface of the photoreceptor 1 after the transfer of the toner image, only the latter is selectively removed and collected by the cleaner main body 60. .

The elastic blade 61 also serves to loosen the residual toner electrostatically attached to the surface of the photoreceptor 1 and facilitate the recovery of the residual toner by the developing device 3. The inventors consider the reason why the elastic blade 61 pressed against the surface of the photoconductor 1 can selectively remove only the irregular foreign matter as described above as follows. That is, first, as a cause of the shape, it is considered that substantially spherical toner is more likely to rotate on the surface of the photoconductor 1 than irregular shaped foreign matter. That is, since the spherical toner is easy to rotate, the elastic blade 6
When the elastic blade 61 is rotated, the elastic blade 61 is lifted while rotating, and slips through between the elastic blade 61 and the photoreceptor 1. It is considered that the toner cannot pass through the space between the photoconductors 1 and is removed from the surface of the photoconductor 1.

Further, as described above, the substantially spherical toner has a particle size of about 5 to 10 μm, whereas foreign matter such as paper dust is as large as about 0.3 mm. It is easy to slip through the body 1 and foreign matter is considered to be one of the causes of difficulty in slipping between the two. It is also considered that the difference in adhesion between the substantially spherical toner and the irregular foreign matter on the surface of the photoconductor 1 is an important cause. In other words, when comparing the two, the irregular foreign matter often comes into contact with the surface of the photoreceptor 1 at only one point, whereas the substantially spherical toner has the same geometrical contact at only one point. However, in actuality, physical or electrostatic adhesive force is generated over a large circular area around the contact point, and the contact point is very close to the surface of the photoreceptor 1. It is considered that the adhesive force to the surface of the photoconductor 1 is larger than that of the foreign matter, and it is difficult to be removed from the surface of the photoconductor 1.

The substantially spherical toner is positively electrostatically adhered to the surface of the photoreceptor 1 in the developing device 3, whereas irregular foreign matter such as paper dust is accidentally generated in a subsequent process. The difference in adhesion between the photoconductor 1 and the surface of the photoconductor 1 is evident from the fact that the two adhere to the surface of the photoconductor 1. The toner used in the above-described device is limited to a substantially spherical toner as described above. As described above, the substantially spherical toner is not removed from the surface of the photoreceptor 1 by the elastic blade 61, passes through the elastic blade 61, is collected by the developing device 3, and is reused for image formation. In addition, since the above-mentioned substantially spherical toner itself has better fluidity and is less likely to be blocked than an irregular-shaped toner, even when the toner is electrostatically attached to the surface of the photoreceptor 1, the elastic blade 61
There is also an advantage that the collection by the developing device 3 can be easily performed only by loosening.

Such a substantially spherical toner can be produced by various conventionally known production methods. In particular, there are three methods of suspension polymerization, dispersion polymerization and spray drying.
The one manufactured by one of the two methods, the particle size distribution is narrow, and by adjusting the manufacturing conditions, it is possible to further reduce the particle size, and can contribute to high image quality of the formed image, It is suitable for use because it has excellent productivity, such as no need for classification and no excluded parts. In particular, a liquid monomer phase mixture containing a water-insoluble polymerizable monomer, which is a raw material of a fixing resin, a polymerization initiator soluble in the monomer, and a coloring agent and other additives, is prepared. For example, a toner produced by a suspension polymerization method in which a monomer in the droplet is polymerized by heating while being suspended and dispersed in an aqueous dispersion medium such as a droplet in a droplet form is preferably used. In this case, each of the droplets suspended and dispersed in the aqueous dispersion medium becomes a toner particle.

Various monomers capable of radical polymerization can be used as the monomer used as the base of the fixing resin in such a suspension polymerization method. Examples of such monomers include various conventionally known compounds such as monovinyl aromatic monomers, acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers, halogenated olefin monomers, and polyvinyl monomers. Can be used.

The monovinyl aromatic monomer is represented by the following general formula (1):

[0030]

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(Wherein 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, an amino group, a nitro group, a vinyl group, a sulfo group, a sodium sulfo group) Represents a nato group, a potassium sulfonato group or a carboxyl group), for example, styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene,
Examples include p-chlorostyrene, p-ethylstyrene, sodium styrenesulfonate, divinylbenzene, and the like.

The acrylic monomer is represented by the following general formula:
(2):

[0033]

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(Wherein, R ³ is a hydrogen atom or a lower alkyl group, R ⁴ is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms,
Represents a hydroxyalkyl group, a vinyl ester group or an aminoalkyl group. ) Acrylic monomer,
For example, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, β -Ethyl hydroxyacrylate, butyl γ-hydroxyacrylate, butyl δ-hydroxyacrylate, ethyl β-hydroxymethacrylate, propyl γ-aminoacrylate, propyl γ-N, N-diethylaminoacrylate,
Examples include ethylene glycol dimethacrylate and tetraethylene glycol dimethacrylate.

The vinyl ester monomer includes the following general formula (3):

[0036]

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(Wherein, R ⁵ represents a hydrogen atom or a lower alkyl group), such as vinyl formate, vinyl acetate, and vinyl propionate. As the vinyl ether monomer, the following general formula (4):

[0038]

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(Wherein R ⁶ represents a monovalent hydrocarbon group having up to 12 carbon atoms), for example, vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether , Vinyl phenyl ether, vinyl cyclohexyl ether and the like. The diolefin monomer includes the following general formula (5):

[0040]

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(Wherein R ⁷ , R ⁸ and R ⁹ are the same or different and each represent a hydrogen atom, a lower alkyl group or a halogen atom), for example, butadiene, isoprene and the like. And chloroprene. As the monoolefin monomer, the following general formula (6):

[0042]

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(Wherein R ¹⁰ and R ¹¹ are the same or different and each represent a hydrogen atom or a lower alkyl group), for example, ethylene, propylene, butene-1, pentene and the like. -1,4-methylpentene-1 and the like. Examples of the halogenated olefin-based monomer include vinyl chloride and vinylidene chloride.

Further, examples of the polyvinyl monomer include divinylbenzene, diallyl phthalate, and tricyanurate. These can be used alone or in combination of two or more. For example, in the case of producing a toner containing the most common styrene-acrylic fixing resin, styrene and an acrylic monomer may be used in combination as monomers.

A polymerization initiator for initiating the polymerization of the above monomer is added to the monomer phase mixture. As the polymerization initiator, those which are insoluble in the aqueous dispersion medium and compatible with the monomer are preferable, for example, azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobis- (4-methoxy-
2,4-dimethylvaleronitrile), 2,2'-azobis- (2-cyclopropylpropionitrile), 2,
2'-azobis- (2-methylpropionitrile),
2,2'-azobis- (2-methylbutyronitrile),
1,1'-azobis- (cyclohexane-1-carbonitrile), 2-phenylazo-4-methoxy-2,4-
Azo compounds such as dimethylvaleronitrile and dimethyl-2,2'-azobis (2-methylpropionate); cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, A peroxide such as lauroyl peroxide can be used, and in the case of performing polymerization by irradiation with ultraviolet light or visible light, a conventionally known photopolymerization initiator can be used. These may be used alone or in combination of two or more.

The polymerization initiator is used in an amount of 0.001 to 10 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the monomer.
The range is from 0.01 to 0.5 parts by weight. It is also possible to initiate polymerization using γ-rays, accelerated electron beams or the like, and in this case, it is not necessary to use a polymerization initiator. Further, the polymerization may be started by combining ultraviolet light and various photosensitizers.

Examples of the colorant include, but are not limited to, <black> carbon black, nigrosine dye (C.I.
No. 50415B), lamp black (CI No. 7)
7266), oil black, azo oil black,
<Red> Dupont oil red (CI No. 2610)
5), Rose Bengal (CI No. 45435), Orient Oil Red # 330 (CI No. 605)
0), <yellow> chrome yellow (CI No. 140
90), quinoline yellow (CI. 47005),
<Green> Malachite Green Oxalate (CIN
o. 42000), <blue> Calco Oil Blue (C.I.
I. No. azoec blue 3), aniline blue (C.I.
I. No. 50405), methylene blue chloride (CI No. 5201), phthalocyanine blue (CI No. 74160), ultramarine blue (CI No. 77103), and the like. These may be used alone or in combination of two or more. The colorant is preferably used in a proportion of 1 to 20 parts by weight per 100 parts by weight of the monomer.

Among the above-mentioned colorants, carbon black in the case of a black toner, particularly carbon black which has been subjected to a surface treatment to improve the affinity with a monomer, can be mentioned as the most suitable. Examples of the surface treatment for improving the affinity of carbon black with a monomer include a coupling treatment with a coupling agent and a grafting treatment with a monomer.

The charge control agent is compounded to control the triboelectric charging property of the toner. Depending on the charging polarity of the toner, either a positive charge control agent or a negative charge control agent is used. In the case of the positively charged toner used in the contact one-component reversal development system in combination with the positively charged photosensitive member as described above, it goes without saying that a charge control agent for controlling the positive charge is used.

Examples of the charge control agent for controlling the positive charge include organic compounds having a basic nitrogen atom, such as basic dyes, aminopyrine, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes and the like. Any of these agents can be used, and in particular, a monomer capable of forming a resin having excellent compatibility with a cationic monomer such as monoallylamine, diallylamine, and triallylamine (for example, when the fixing resin is In the case of a general styrene-acrylic type, a copolymer with styrene, at least one of acrylic ester and methacrylic ester) is preferably used. These charge control agents are excellent in the effect of improving the transfer efficiency of the toner image from the photoreceptor surface to the object to be transferred and reducing the residual toner.

On the other hand, as charge control agents for controlling negative charges, nigrosine base (CI5045), oil black (CI
26150), oil-soluble dyes such as Bontron S and Spiron Black; charge-controlling resins such as styrene-styrene sulfonic acid copolymer; compounds containing carboxy groups (for example, metal chelates of alkyl salicylic acid); metal complex dyes;
Examples thereof include fatty acid metal soaps, resin acid soaps, and metal naphthenates.

The charge control agent is used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the monomer. In order to impart an anti-offset effect to the toner, an anti-offset agent may be added. Examples of the offset preventing agent include aliphatic hydrocarbons, aliphatic metal salts, higher fatty acids, fatty acid esters or partially saponified products thereof, silicone oil, various waxes and the like. Among them, the weight average molecular weight is 10
Aliphatic hydrocarbons of about 00 to 10,000 are preferred.
Specifically, one or a combination of two or more of low-molecular-weight polypropylene, low-molecular-weight polyethylene, paraffin wax, a low-molecular-weight olefin polymer composed of olefin units having 4 or more carbon atoms, and silicone oil are suitable.

The anti-offset agent is used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, per 100 parts by weight of the monomer.
Used in parts by weight. Components that can be added to the monomer phase mixture in addition to the above components include, for example, a crosslinking agent. The cross-linking agent is compounded to cross-link the fixing resin to improve the mechanical or thermal properties of the electrophotographic toner. For example, a divinyl compound such as divinyl benzene; diallyl phthalate, diallyl isophthalate, diallyl Diallyl compounds such as adipate, diallyl glycolate, diallyl maleate, diallyl sebacate; triallyl compounds such as triallyl phosphate, triallyl aconitate, triallyl cyanurate, triallymic acid allyl ester, pyromellitic acid allyl ester; 6-hexanediol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate Diacrylate compounds such as butadiene, butylene glycol diacrylate, pentaerythritol diacrylate and 1,4-butanediol diacrylate; triacrylate compounds such as trimethylolpropane triacrylate and pentaerythritol triacrylate; 1,6-hexanediol diacrylate Methacrylate, neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate,
Dimethacrylate compounds such as diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, butylene glycol dimethacrylate; trimethacrylate compounds such as trimethylolpropane trimethacrylate; dipentaerythritol hexaacrylate, tetramethylol methane tetraacrylate, N, N ,
Poly (meth) acrylate compounds such as acrylic acid esters of N ', N'-tetrakis (β-hydroxyethyl) ethylenediamine; allyl-acrylic compounds such as allyl acrylate and allyl methacrylate; N, N'-methylenebisacrylamide; And acrylamide compounds such as N'-methylenebismethacrylamide; and difunctional to polyfunctional monomers such as prepolymers such as polyurethane acrylate, epoxy acrylate, polyether acrylate, and polyester acrylate.

The crosslinking agent is used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the monomer. In addition, various additives such as stabilizers (of course, those which are soluble in the monomer phase mixture and insoluble in the aqueous dispersion medium) may be blended at an appropriate ratio. On the other hand, as the aqueous dispersion medium for suspending and dispersing the monomer phase mixture composed of the above components, water, or a water-based medium, a mixed solvent incompatible with the monomer phase mixture can be mentioned, and water is most preferably used. Adopted.

It is preferable to add a dispersion stabilizer to the aqueous dispersion medium in order to stabilize the dispersibility of the monomer phase droplets. Examples of the dispersion stabilizer include water-soluble polymers such as polyvinyl alcohol and inorganic fine particles that are hardly water-soluble. However, considering the environmental resistance, fluidity, or charging characteristics of the toner, the surface of toner particles Than a water-soluble polymer that may be taken up and make the surface hygroscopic,
Poorly water-soluble inorganic fine particles are preferably employed. The addition amount of the inorganic fine particles as the dispersion stabilizer may be the same as in the conventional case.

It is preferable to add a surfactant to the aqueous dispersion medium in order to obtain a good dispersion state of the monomer phase mixture. The surfactant is preferably added after the addition of the monomer phase mixture in order to prevent biting of bubbles and the like. As the surfactant, various conventionally known surfactants of anionic, cationic or nonionic type can be used,
Considering that the target toner has a particle size of about 10 μm, the toner needs to have excellent suspension / dispersion ability, and is easy to remove from the toner in order not to affect the characteristics of the toner after production. It is desirable. The surfactant is
It is added at an appropriate ratio depending on the ratio of the monomer phase mixture and the aqueous dispersion medium.

The particle size of the toner is not particularly limited, but in order to obtain a high-resolution image, the central particle size is in the range of 5 to 10 μm, especially around 6 μm, and the particle size dispersion is in the range of 1.50 or less, especially 1 to 50 μm. It is preferably in the range of .45 or less. The toner produced as described above can be further surface-treated with an external additive in order to adjust its fluidity and the like. As such external additives, various conventionally known external additives can be used. In particular, in order to improve the transfer efficiency of the toner image from the photoreceptor surface to the object to be transferred and reduce the residual toner. Preferably, silica fine powder having a specific surface area of 150 m ² / g or less as measured by the BET method is suitably used. For the same reason, the toner preferably has an apparent density of 0.30 g / cc or more after being treated with the silica fine powder.

[0058]

【Example】

<< Production of Toner I >> Each of the following components was rotated at a rotational speed of 5 with a high-speed stirrer (TK homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.).
000r. p. m. For 5 minutes to produce a monomer phase. (Components) (parts by weight) Polymerizable monomer Styrene 82 2-ethylhexyl methacrylate 18 Crosslinking agent Diethylene glycol dimethacrylate 2 Coloring agent Grafted carbon black ^* 15 Charge control agent Bontron N-07 0.5 Styrene-diallylamine Copolymer ^{* 2} 10 Polymerization initiator 2,2'-azobis- (2,4-dimethylvaleronitrile) 2.5 Azobisisobutyronitrile 0.32 * 1: Carbon black was treated in styrene. thing.

* 2: The ratio of styrene to diallylamine is 9: 1 in molar ratio. Next, the above monomer phase is
The mixture was mixed in an aqueous dispersion medium composed of the following components, and rotated at 10,000 rpm using the high-speed stirrer described above. p. m. At 1
By stirring for 0 minute, a suspension having an average droplet diameter of about 9 μm was prepared. (Ingredient) (parts by weight) ・ Ion-exchanged water 670 ・ Dispersion stabilizer Tricalcium phosphate 7 Sodium dodecylbenzenesulfonate 0.044 Next, this suspension was equipped with a stirrer, a nitrogen inlet tube and a condenser. Transfer to a 3-liter separable flask purged with nitrogen, and rotate at 120 rpm. p. m. After heating to 80 ° C. for 5 hours while stirring at 50 ° C., the mixture was cooled to room temperature.

Then, filtration, washing with ion-exchanged water,
Through a drying step, substantially spherical toner particles having a center particle diameter of 8.5 μm were produced, and 100 parts by weight of the toner particles were mixed with a silica fine powder having a specific surface area of 105 m ² / g (H2015EP manufactured by Wacker Inc.). By adding 6 parts by weight, a positively charged toner having an overall apparent density of 0.39 g / cc and a charge amount of +30 μC / g was produced. << Production of Toner II >> The following components were melt-kneaded and pulverized and classified to produce amorphous toner particles having an average particle size of 9.1 μm.

(Component) (parts by weight) Fixing resin Styrene-acrylic copolymer 100 Colorant carbon black 8 Charge control agent Bontron N-070.5 And 100 parts by weight of the toner particles 0.6 parts by weight of the resulting silica fine powder (H2015EP manufactured by Wacker Inc.) was added to produce a positively charged toner having an overall apparent density of 0.29 g / cc and a charge amount of +16 μC / g. Example 1 A developing device of a plain paper facsimile (Model No. TC-670 manufactured by Mita Kogyo Co., Ltd.) equipped with a positive charging type photoreceptor was replaced with a developing device 3 (photoreceptor) of a contact one-component reversal developing system shown in FIG. 1 using a developing roller 31 made of urethane rubber in contact with the surface of the facsimile machine 1 and using the facsimile toner recovery cleaner (elastic blade type) as the paper powder cleaner 6 as it is. An apparatus for carrying out the image forming method described above was produced. Then, in this apparatus, a substantially spherical positively-charged toner manufactured in the toner manufacturing I,
When 30,000 sheets of continuous images were formed using plain paper for PPC, white streaks and fogging, which might be caused by the mixing of paper dust, did not occur until the end. Therefore, for the first formed image and the 30,000th formed image, the image density of the image portion and the blank portion are respectively measured using a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.). Fog density was measured.

After the formation of 30,000 sheets of images, the total amount of toner consumed and the total amount of paper dust and toner collected in the cleaner body 60 of the paper dust cleaner 6 were measured. Comparative Example 1 Continuous image formation was performed in the same manner as in Example 1 while a conductive brush was brought into contact with the surface of the photoconductor in place of the paper dust cleaner 6, and it was found that paper dust was mixed in the formed image. The test was stopped after 5,000 sheets because white streaks and fogging occurred. Comparative Example 2 Continuous image formation of 30,000 sheets was performed in the same manner as in Example 1 except that the irregularly-shaped positively-charged toner produced in Production II of the toner was used. No white streaks or fogging, which could be attributed to this, occurred. Therefore, for the first formed image and the 30,000th formed image, the image density of the image portion and the blank portion are respectively measured using a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.). Fog density was measured.

After the formation of 30,000 sheets of images, the total consumption of toner and the total amount of paper dust and toner collected in the cleaner main body 60 of the paper dust cleaner 6 were measured. Table 1 shows the above results.

[0064]

[Table 1]

Further, with respect to Example 1 and Comparative Example 2,
After forming 30,000 sheets of images, the inside of the cleaner 60 was visually observed. In the comparative example 2, the collected matter collected by the cleaner 60 was a mixture of a large amount of toner and a small amount of paper powder. Most of the collected material collected by the cleaner 60 in Example 1 was paper powder, and the amount of toner was very small.

From the above results, it can be seen that the use of the elastic blade type cleaner makes it possible to surely remove the paper dust, and that the use of the substantially spherical toner makes it possible to reduce the paper dust as compared with the case where the amorphous toner is used. It has been found that since only the toner can be selectively collected, the amount of toner collected together with the paper powder decreases, and as a result, the toner amount as a whole can also be reduced.

[0067]

As described above in detail, according to the image forming method of the present invention, when the toner remaining on the surface of the photoreceptor after the image transfer is collected by the developing device and reused, the toner is contained in the toner. Foreign matter that causes image defects and the like when mixed in can be more reliably removed from the surface of the photoconductor by using an elastic blade that is in contact with the surface of the photoconductor. Therefore, the image forming method according to the present invention has a specific operation and effect that contributes to further downsizing of an image forming apparatus such as a laser beam printer, maintenance free, environmental protection, resource saving, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an example of an apparatus for performing an image forming method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 3 Developing device 61 Elastic blade

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Shinichi Higo 1-2-28 Tamazo, Chuo-ku, Osaka-shi, Osaka Mita Kogyo Co., Ltd. (56) References JP-A-5-346751 (JP, A) JP-A-6-194998 (JP, A) JP-A-3-219275 (JP, A) JP-A-4-20987 (JP, A) JP-A-4-20988 (JP, A) JP-A-4-267282 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 21/00 G03G 21/10-21/12 G03G 15/08-15/08 507

Claims (1)

(57) [Claims] An electrostatic latent image formed on a surface of a photoreceptor is brought into contact with a toner by a developing device to visualize the electrostatic latent image into a toner image, and the toner image is transferred to an object to be transferred. Then, in the image forming method in which the toner remaining on the surface of the photoreceptor is collected and reused by the developing device, a substantially spherical toner is used, and the photoreceptor after the toner image is transferred to paper. Elastic blades that remove spherical particles pressed from the surface of the photoreceptor while passing spherical particles pressed against the surface of the photoreceptor but do not pass irregularly shaped particles selectively remove irregular foreign matter attached to the surface of the photoreceptor with toner. And an image forming method.