JP3416444B2 - Image forming method and non-magnetic toner - 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 used in a recording method using an electrophotographic method, an electrostatic recording method or the like. More specifically, the present invention relates to a toner and an image forming method used in a copying machine, a printer or a fax machine, which forms a toner image on an electrostatic latent image carrier and transfers the toner image onto a transfer material to form an image. .

[0002]

2. Description of the Related Art Conventionally, a large number of electrophotographic methods are known. Generally, a photoconductive substance is used to form an electrostatic latent image on an image bearing member (photoreceptor) by various means.
Then, the latent image is developed with toner to form a visible image, and if necessary, the toner image is transferred to a transfer material such as paper, and then heat,
The toner image is fixed on the transfer material by pressure, heat pressure or the like to obtain a copy or a print.

As a method for visualizing an electrostatic latent image, a cascade developing method, a magnetic brush developing method, a pressure developing method, a one-component developing method and the like are known. Furthermore, a method is known in which a magnetic toner is used and a rotating sleeve containing a magnet is used to fly an electric field between the photosensitive member and the sleeve.

Unlike the two-component developing method, the one-component developing method does not require carrier particles such as glass beads, iron powder, and magnetic ferrite carrier particles, so that the developing device itself can be made compact and lightweight. Further, in the two-component developing method using toner and carrier, it is necessary to keep the mixing ratio of carrier and toner constant, so that an apparatus for detecting toner concentration and successively supplying a required amount of toner is required. Therefore, the developing device tends to be large and heavy. Such a device is not required in the one-component developing method, and it is preferable because it can be made small and light.

LBP printers or LED printers have become the mainstream as printer devices utilizing electrophotography. Conventional direction of technology 240, 30
What was 0 dpi is 400, 600, 800 dpi
And high resolution is coming. Therefore, the developing method is required to have high definition. Copiers are also becoming more sophisticated, and as a result, they are moving toward digitalization. This method is mainly a method of forming an electrostatic charge image with a laser, and is progressing toward high resolution. Here, as in the case of the printer, a high-resolution and high-definition developing method is required. Due to this, the toner has been made smaller in particle size, and is disclosed in JP-A-1-112253, JP-A-1-191156, JP-A-2-214156, JP-A-2-284158, and JP-A-3-1843. 181
No. 952 and Japanese Patent Laid-Open No. 4-162048 propose a toner having a specific particle size distribution and a small particle size.

The toner image formed on the photoconductor in the developing process is transferred to the transfer material in the transfer process, but the transfer residual toner remaining on the photoconductor is cleaned in the cleaning process.
The cleaned toner is stored in the waste toner container. For this cleaning step, conventionally, blend cleaning, fur brush cleaning, roller cleaning, etc. have been used. The squeezing method also mechanically scrapes off the transfer residual toner, or dams it and collects it in a waste toner container. Problems due to such a cleaning member being pressed against the surface of the photoconductor tend to occur. For example, the surface of the photoconductor is abraded by strongly pressing the member, which shortens the life of the photoconductor. From the viewpoint of the apparatus, the image forming apparatus inevitably becomes large in size due to the provision of the cleaning device, which is one of the necks when aiming at downsizing of the image forming apparatus.

Further, from the viewpoint of ecology, a system in which waste toner does not occur or a system in which the amount of waste toner is small is desired in the sense of effective utilization of toner, and therefore a toner having a high transfer efficiency is required. .

An image forming method conventionally called cleaning at the same time as development or cleanerless is disclosed in JP-A-5-2287.
As proposed in Japanese Patent Laid-Open Publication No. JP-A No. 2003-242242, the focus was on a positive memory or a negative memory due to the influence of transfer residual toner on the image. However, with the increasing use of electrophotography, there is a need to transfer toner images to various transfer materials, and in this sense, there is a long-awaited demand for those that are satisfactory for various transfer materials. There is.

Japanese Unexamined Patent Publication (Kokai) No. 2-511168 uses a spherical toner and a spherical carrier to obtain stable charging characteristics, and does not refer to a toner produced by a pulverization method. .

Furthermore, JP-A-59-133573, JP-A-62-203182, and JP-A-63-1331, which disclose techniques relating to cleanerless, are disclosed.
79, JP 64-20587, and JP 2
In JP-A-3030272, JP-A-5-2289, JP-A-5-53482, and JP-A-5-61383, no specific mention is made of the toner composition. The publication that describes image exposure proposes a method of irradiating light of high intensity or using a toner that transmits light of the exposure wavelength.

However, simply increasing the exposure intensity causes bleeding of the dots of the electrostatic latent image, which deteriorates the reproducibility of isolated dots and lowers the resolution in terms of image quality. In particular, a graphic image has poor gradation.

Further, in the method using a toner that transmits light of the exposure wavelength, the main cause of interrupting the exposure is scattering of the exposure on the surface of the toner particles rather than coloring of the toner itself. The effect is weak. Further, the selection range of the colorant for the toner is narrowed. In addition, when forming a full-color image, at least three types of exposure means having different wavelengths are required, which goes against the simplification of the apparatus, which is one of the features of simultaneous cleaning during development.

Further, in the simultaneous development cleaning which essentially does not have a cleaning device, it is preferable to rub the surface of the electrostatic latent image bearing member with the toner and the toner bearing member included in the developing means. Deterioration, toner carrier surface deterioration, electrostatic latent image carrier surface deterioration or wear is likely to occur, and the deterioration of durability characteristics is a problem, and conventional technology has not sufficiently solved it. It was rare.

Japanese Unexamined Patent Publication (Kokai) No. 3-259161 proposes a non-magnetic one-component developer in which the shape factor, the specific surface area and the particle size are specified. However, the developer specified in the publication further improves durability. Need to improve.

In Japanese Patent Laid-Open No. 61-279864, the shape factor SF-1 is 120 to 180 and SF-2 is SF-2.
Toners of 110 to 130 have been proposed. However, as a result of the additional test of the example of the publication, the transfer efficiency is low and further improvement is required.

Further, Japanese Patent Application Laid-Open No. 63-235953 proposes a magnetic toner spherically formed by a mechanical impact force. However, there is a need to further improve the transfer efficiency.

In recent years, from the viewpoint of environmental protection, a contact member to which a bias is applied so as to contact the photoconductor is used from the conventionally used primary charging using corona discharge and the transfer process using corona discharge. The primary charging or / and transfer processes that have been noted have received attention. For example, the method is proposed in JP-A-63-149669 and JP-A-2-123385. These relate to a contact charging method and a contact transfer method. A charging step of bringing a conductive elastic roller for charging into contact with the electrostatic latent image carrier and uniformly charging the electrostatic latent image carrier while applying a voltage to the conductive roller, and then an exposing step of exposing; After the toner image is obtained by the developing process, the transfer material is applied with a voltage to the electrostatic latent image bearing member by pressing the transfer material while passing through the transfer material, and the toner image on the electrostatic latent image bearing member is passed. After being transferred to a transfer material, a fixed image is obtained through a fixing process.

However, in such a roller transfer system which does not use corona discharge, since the transfer member is brought into contact with the photoconductor through the transfer member during transfer, the toner image formed on the photoconductor is transferred to the transfer material. When the toner image is transferred to the toner image, the toner image is pressed against it, and a problem of partial transfer failure (refer to FIG. 8), which is referred to as a void in transfer, is likely to occur.

When the toner has a smaller diameter, the adhesion force (image force, van der Waals force, etc.) of the toner particles to the photoconductor becomes larger than the Coulomb force applied to the toner particles during the transfer, and as a result, the transfer residue is left. Toner tends to increase.

Therefore, it has been required that the toner and the photoconductor used in such an image forming method have excellent releasability.

[0021]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method which solves the above-mentioned problems of the prior art.

It is an object of the present invention to provide an image forming method which has no or little influence of positive or negative memory.

It is an object of the present invention to use various transfer materials (eg,
An object of the present invention is to provide an image forming method having extremely good transferability even for thick papers, transparent films for overhead projectors, etc.).

An object of the present invention is to provide an image forming method which essentially does not have a cleaning device only for cleaning the surface of an electrostatic latent image bearing member.

It is a further object of the present invention to provide an image forming method which is excellent in transferability, has a small amount of transfer residual toner, does not cause voids in transfer even in a roller transfer system, or suppresses these phenomena. It is in.

[0026]

SUMMARY OF THE INVENTION The present invention comprises a charging step of charging an electrostatic latent image bearing member by a charging means, and an exposing step of exposing the charged electrostatic latent image bearing member to form an electrostatic latent image. , A developing step of developing the electrostatic latent image with a non-magnetic one-component toner included in the developing means to form a toner image on the electrostatic latent image carrier, transferring the toner image with or without an intermediate transfer member A non-magnetic toner particle of the non-magnetic one-component toner comprises a transfer step of transferring to a material, and a step of collecting the toner remaining on the electrostatic latent image bearing member after transfer to a developing means in the developing step. , The shape factor SF-1 is 120 to 160, the shape factor SF-2 is 115 to 140, the weight average particle diameter is 4 to 9 μm, and the BET specific surface area measured using nitrogen gas is 1. 4 to 2.1 m ² / cm ³ , primary number average particle A non-magnetic toner comprising an inorganic fine particle (a) having a diameter of 50 nm or less and a true spherical fine particle (b) having a primary number average particle diameter of 50 to 1000 nm and a surface area shape sphericity ψ of 0.91 to 1.00. The non-magnetic one-component toner externally added to the particles has a number average particle diameter of 3.
5 to 8.0 μm, B measured using nitrogen gas
The ET specific surface area is Sb (m ² / cm ³ ), and the specific surface area per unit volume calculated from the weight average particle diameter when the non-magnetic one-component toner is assumed to be a true sphere is St (m ² / cm ³ ). In this case, the image forming method is characterized by satisfying the following conditions: 3.4 ≦ Sb ≦ 6.3 3.0 ≦ Sb / St ≦ 7.0 Sb ≧ St × 1.5 + 1.5.

[0027]

According to the present invention, a positive memory which improves the transfer efficiency and reduces the residual toner after transfer, which is generated in a system called cleaningless or simultaneous development cleaning, which essentially has no cleaning device. Alternatively, negative memory can be essentially prevented.

In the present invention, SF-indicating the shape factor
1 and SF-2 are, for example, Hitachi FE-SEM
(S-800) is used to randomly sample 100 non-magnetic toner particle images of 2 μm or more which are magnified 1000 times, and the image information is transmitted via an interface, for example, an image analysis device (Luzex III) manufactured by Nicore Co. Introduced into and analyzed, the value calculated by the following equation is used as the shape factor S
It is defined as F-1 and SF-2.

In the above measuring method, the S of non-magnetic toner particles is
There is substantially no difference in the measured values between F-1 and SF-2, SF-1 and SF-2 of the non-magnetic toner to which the inorganic fine particles (a) and the true spherical particles (b) are externally added.

[0030]

[Outer 1] (In the formula, MXLNG is the absolute maximum length of the particle, PERIME
Is the perimeter of the particle, and AREA is the projected area of the particle. )

The shape factor SF-1 indicates the degree of roundness of the toner, and the shape factor SF-2 indicates the degree of unevenness of the toner.

When the shape factor SF-1 of the toner is less than 120 or the spherical coefficient SF-2 of the toner is less than 115, toner fusion is generally apt to occur on the toner carrier. When the shape factor SF-1 of the toner exceeds 160, the toner is separated from the spherical shape and approaches an irregular shape, the toner is easily crushed in the developing device, the particle size distribution is fluctuated, and the triboelectric charge amount distribution is apt to be broad. Fogging and reverse fog are likely to occur. If the SF-2 exceeds 140, the transfer efficiency of the toner image at the time of transfer from the electrostatic latent image carrier to the transfer material decreases,
In addition, it is not preferable because a character or line image is missing in the transfer. Those obtained by surface-treating non-magnetic toner particles produced by a pulverization method are preferably used.

The values B and S obtained by subtracting 100 from the value of SF-2.
The value of the ratio B / A to the value A obtained by subtracting 100 from the value of F-1 shows the slope of the straight line passing through the origin in FIG. 13, and this value is preferably 1.0 or less, more preferably 0.2. ~
0.9 (further 0.35 to 0.85),
It is preferable because the transferability is improved while maintaining the developability of the non-magnetic toner.

The non-magnetic toner particles used in the image forming method of the present invention have SF-1 of 120 to 160 and S
F-2 is 115 to 140 and the weight average particle diameter is 4 to
Inorganic fine particles (a) having a particle size of 9 μm and a primary number average particle size of 50 nm or less, and a primary number average particle size of 50 to 1000
nm, and the surface area shape sphericity ψ is 0.91 to 1.0
Since the spherical fine particles (b) of 0 are externally added to the non-magnetic toner particles, the transferability is excellent, the durability of a large number of sheets is excellent, and the electrostatic latent image carrier is formed after the transferring step during the developing step. It is easy to collect the remaining toner in the developing device and is excellent in dot reproducibility of the digital latent image.

Inorganic fine particles (a) on the surface of the non-magnetic toner particles
Also, by having the spherical particles (b), voids in the transfer of the character image and line image of the non-magnetic toner are improved.

Further, in the present invention, the BET per unit volume of the non-magnetic toner measured by the BET method.
The relationship between the specific surface area Sb and the specific surface area St (St = 6 / D4) per unit volume calculated from the weight average particle diameter (D ₄ ) assuming that the non-magnetic toner is a true sphere is 3.0 ≦ Sb / S
t ≦ 7.0 and Sb ≧ St × 1.5 + 1.5. Further, the non-magnetic toner used in the present invention has a number average particle diameter of D ₁ (μm) and Sb (m ² / cm ³ ), and the relationship between D ₁ and Sb is

It is preferable that 15 <D ₁ × Sb ≦ 40. Further, D ₁ is 3.5 to 8.0 μ.
m, and Sb is 3.4 to 6.3 m ² / cm ³ .

The true density for obtaining the volume from the weight of the sample can be measured using, for example, a dry automatic densimeter "Acupic 1330" manufactured by Shimadzu Corporation.

If the ratio Sb / St is less than 3.0 times, the transfer efficiency is lowered, and if it exceeds 7.0 times, the image density is lowered. This is because the inorganic fine particles externally added to the non-magnetic toner particles are powder (b) and true spherical fine particles (b) between the non-magnetic toner particles and the toner image carrier and between the non-magnetic toner particles and the electrostatic latent image. It is considered that this is due to the fact that it effectively acts as a spacer between itself and the surface of the carrier.

The specific surface area of the non-magnetic toner in the above range is the specific surface area of the non-magnetic toner particles and the specific surface area of the inorganic fine particles (a) and the true spherical particles (b) to be added to the non-magnetic toner particles, the addition amount and the addition mixture. It is achieved by controlling the strength.

Furthermore, since the inorganic fine particles (a) and the true spherical particles (b) are effectively used, the BET specific surface area Sr per volume measured using nitrogen gas of the toner particles is 1.4 to 2.1 m. ^{It is 2} / cm ³ , and the theoretical specific surface area per volume calculated from the weight average particle diameter when the toner is assumed to be a true sphere is preferably 1.5 to 2.5 times.

Inorganic fine particles (a) and true spherical fine particles (b)
The BET specific surface area of the non-magnetic toner is 1.
It is preferable to increase by 5 m ² / cm ³ or more. Radius 1 nm in toner particles before addition of inorganic fine particles (a)
6 in the integrated pore area ratio curve for pores of -100 nm
The 0% pore radius is preferably 3.5 nm or less. At this time, the BET specific surface area Sb of the toner and the BET of the toner particles
The value of the ratio Sb / Sr of the specific surface area Sr is preferably in the range of 2-5.

These are because the inorganic fine particles (a) behave more effectively by reducing the number of pores in the toner particles that are larger than the primary particle diameter of the inorganic fine particles (a) added to the toner particles, and the transfer efficiency is improved. It is thought to improve.

The specific surface area is determined according to the BET method by using a specific surface area measuring device (Autosoap 1; manufactured by Yuasa Ionics Co., Ltd.) to adsorb nitrogen gas on the sample surface, and calculating the specific surface area using the BET multipoint method. Further, the 60% pore radius is obtained from the integrated pore area ratio curve with respect to the desorption side pore radius. In Auto Soap 1, the pore size distribution is calculated by Bar
rett, Joyner & Harenda (B.
J. H.). J. The H method is used.

In order to faithfully develop finer latent image dots for higher image quality, the toner has a weight average diameter of 4 μm to 9 μm.
What is μm is used. In the toner having a weight average diameter of less than 4 μm, a large amount of toner remains on the photoconductor due to a decrease in transfer efficiency, and moreover, it is likely to cause uneven image unevenness due to fog and transfer failure. Is not preferable. When the weight average diameter of the toner exceeds 9 μm, scattering of characters and line images is likely to occur.

For the toner particles and the average particle size and particle size distribution of the toner, a Coulter counter TA-II type or a Coulter Multisizer (manufactured by Coulter) is used, and an interface (manufactured by Nikkaki) for outputting number distribution and volume distribution and PC9801. Personal computer (NE
(Made by C) is connected, and a 1% NaCl aqueous solution is prepared by using primary sodium chloride as an electrolytic solution. For example, ISOTON
R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, a surfactant (preferably alkylbenzene sulfonate) as a dispersant is added in an amount of 0.1 to 5 in 100 to 150 ml of the electrolytic aqueous solution.
ml, and 2 to 20 mg of the measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and the Coulter Counter TA-II type was used to prepare a 100 μm aperture as an aperture.
The volume distribution and the number distribution were calculated by measuring the volume and the number of the toner having a particle size of μm or more. Then, the volume-based weight average particle diameter (D ₄ ) obtained from the volume distribution and the number-based number average particle diameter (D ₁ ) obtained from the number distribution according to the present invention are obtained.

The amount of charge per unit area of the non-magnetic toner used in the present invention (two-component method) is 30 to 80 mC /
It is preferable that it is kg (more preferably 40 to 70 mC / kg) in order to improve transfer efficiency in a transfer method using a transfer member to which a voltage is applied.

The method for measuring the charge amount (two-component tribo) of the non-magnetic toner according to the present invention by the two-component method will be described below.

20 in an environment of temperature 23 ° C. and relative humidity 60%
0 mesh pass-300 mesh on iron powder (EFV2
00/300; manufactured by Powder Tech Co., Ltd.) and iron powder 9.
A mixture of 0.5 g of toner and 5 g of 50 to 100 m
Place in a 1-volume polyethylene bottle and shake by hand 50 times. Next, the mixture 1. was placed in a metal measuring container 72 having a screen 73 of 500 mesh on the bottom as shown in FIG.
0-1.2g is put and the metallic lid 74 is put. At this time, the total weight of the measurement container 72 is weighed and set as W ₁ (g). Next, in the suction device (at least the part that is in contact with the measurement container 72 is an insulator), suction is performed from the suction port 77 and the air volume control valve 76 is adjusted to adjust the pressure of the vacuum gauge 75 to 2450 Pa (250 mm).
Aq). In this state, suction is performed for 1 minute to remove the toner by suction. The electric charge of the electrometer 79 at this time is V (volt)
And Here, 78 is a condenser whose capacity is C (μ
F). In addition, weigh the entire measuring machine after suction and W ₂
(G). Triboelectric charge of this toner (mC / kg)
Is calculated as follows.

Triboelectric charge amount (mC / kg) = CV / (W ₁ −W ₂ ).

As the binder resin used for the non-magnetic toner, gel permeation chromatogram (GP
In the molecular weight distribution of C), it is preferable that the peak on the low molecular weight side is in the molecular weight range of 3000 to 15000, in order to control the shape of the toner particles produced by the pulverization method by thermal mechanical impact. When the molecular weight at the peak position on the low molecular weight side exceeds 15,000, the shape factors SF-1 and SF
-2 is difficult to control within the scope of the present invention. When the molecular weight at the peak position is less than 3,000, fusion is likely to occur in the apparatus during surface treatment of toner particles. The molecular weight is measured by GPC. As a specific method for measuring GPC, the toner was previously used in a tetrahydrofuran (TH) using a Soxhlet extractor.
F) The sample was extracted with a solvent for 20 hours, and the column configuration was Showa Denko A-801, 802, 803, 80.
4,805,806,807 are connected and the molecular weight distribution is measured using the standard polystyrene resin calibration curve.

A resin having a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn) of 2 to 100 is preferable.

The glass transition point Tg of the toner is 50 ° C. to 75 ° C. (more preferably 52 ° C.) from the viewpoint of fixability and storability.
(° C to 70 ° C) is preferable.

To measure the glass transition point Tg of the toner, for example, a high precision internal heat input compensation type differential scanning calorimeter such as DSC-7 manufactured by Perkin Elmer is used.
The measuring method is performed according to ASTM D3418-82. In the present invention, the sample is heated once to take a previous history, then rapidly cooled, and again at a temperature rate of 10 ° C./min and a temperature of 0 ° C.
DSC measured when the temperature is raised in the range of ~ 200 ° C
Use a curve.

As the binder resin of the toner, polystyrene; a homopolymer of a styrene substitution product such as poly-p-chlorostyrene and polyvinyltoluene; a styrene-p-chlorostyrene copolymer, a styrene-vinyltoluene copolymer, Styrene-vinyl naphthalene copolymer, styrene-
Acrylic ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer Styrene copolymers such as polymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers; polyvinyl chloride, phenolic resins, natural modifications Phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin , Coumarone-indene resin, petroleum resin, or the like can be used. Cross-linked styrenic resins are also preferred binder resins.

Comonomers for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid. Acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, monocarboxylic acid having a double bond such as acrylamide or a substituted product thereof; maleic acid, butyl maleate, methyl maleate , A dicarboxylic acid having a double bond such as dimethyl maleate and its substituted products; vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; ethylene olefins such as ethylene, propylene and butylene. Vinyl methyl ketone, such as vinyl vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl propionate ether. These vinyl monomers are used alone or in combination. A compound having two or more polymerizable double bonds is mainly used as the cross-linking agent. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; divinylaniline and divinyl ether. , A divinyl compound such as divinyl sulfide and divinyl sulfone; and a compound having three or more vinyl groups. These can be used alone or in combination.

It is also preferable to include the following waxes in the toner particles in order to improve the releasability from the fixing member at the time of heating and pressing and fixing and the fixing property. Paraffin wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, carnauba wax and its derivatives. Examples of the derivative include oxides, block copolymers with vinyl monomers, and graft modified products.

In addition, long-chain alcohols, long-chain fatty acids, acid amides, esters, ketones, hydrogenated castor oil and its derivatives, plant wax, animal wax, mineral wax, petrolactam and the like can be used.

For the non-magnetic toner, it is preferable to use a charge control agent mixed with the toner particles (internal addition) or mixed with the toner particles (external addition). The charge control agent enables optimum control of the amount of charge according to the developing system. The following substances control the toner to be negatively charged.

Organic metal complexes and chelate compounds are effective, for example, monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid type metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

The following substances are used to control the positive chargeability.

Modifications with nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate,
And their analogs, such as onium salts such as phosphonium salts, lake pigments thereof, triphenylmethane dyes and lake pigments thereof (as a laker, phosphorus tungstic acid, phosphorus molybdic acid, phosphorus tungsten molybdic acid, tannic acid) , Lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids;
Dibutyltin oxide, dioctyltin oxide,
Diorgano tin oxides such as dicyclohexyl tin oxide; diorgano tin borates such as dibutyl tin borate, dioctyl tin borate and dicyclohexyl tin borate. These alone or 2
A combination of more than one type can be used.

The charge control agents described above are preferably used in the form of fine particles, and in this case, the number average particle diameter of these charge control agents is preferably 4 μm or less, more preferably 3 μm or less. When these charge control agents are internally added to the toner particles, it is preferable to use 0.1 to 20 parts by weight, particularly 0.2 to 10 parts by weight, based on 100 parts by weight of the binder resin.

The colorant used in the non-magnetic toner is carbon black as the black colorant, and the following yellow /
A black-toned one using a magenta / cyan colorant is used.

As the yellow colorant, condensed azo compounds, isoindolinone compounds, anthraquinone compounds,
Compounds represented by azo metal complexes, methine compounds and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 6
2, 74, 83, 93, 94, 95, 97, 109, 1
10, 111, 120, 127, 128, 129, 14
7, 168, 174, 176, 180, 181, 191
Etc. are preferably used.

As the magenta colorant, a condensed azo compound, a diketopyrrolopyrrole compound, an anthraquinone, a quinacridone compound, a basic dye lake compound, a naphthol compound, a benzimidazolone compound, a thioindigo compound, and a perylene compound are used. Specifically, C.I.
I. Pigment Red 2, 3, 5, 6, 7, 23, 4
8; 2, 48; 3, 48; 4, 57; 1, 81; 1, 1
44, 146, 166, 169, 177, 184, 18
5,202,206,220,221,254 are particularly preferred.

As the cyan colorant, a copper phthalocyanine compound and its derivative, an anthraquinone compound, a basic dye lake compound and the like can be used. Specifically, C.I. I.
Pigment Blue 1, 7, 15, 15: 1, 15: 2,
15: 3, 15: 4, 60, 62, 66 and the like can be used particularly preferably.

These colorants may be used alone or in combination, or in the state of solid solution. The colorant is selected in terms of hue angle, saturation, lightness, weather resistance, OHP transparency, and dispersibility in the toner. The colorant is added in an amount of 1 to 20 parts by weight based on 100 parts by weight of the binder resin.

The inorganic fine particles (a) are preferably selected from silica, alumina, titania or a complex oxide thereof in order to improve the charging stability, developability, fluidity and storage stability of the non-magnetic toner. Furthermore, silica is more preferable. As the silica, both a so-called dry method produced by vapor phase oxidation of a silicon halide or an alkoxide or a dry silica called fumed silica and a so-called wet silica produced from alkoxide, water glass or the like can be used. Dry silica having less silanol groups on the surface and inside the fine silica powder and less production residues such as Na ₂ O and SO ₃ ^2- is preferable. In the case of dry silica, it is also possible to obtain a composite fine powder of silica and another metal oxide by using another metal halogen compound such as aluminum chloride and titanium chloride in the manufacturing process together with the silicon halogen compound. You may use it.

[0070] Inorganic fine particles (a) is a BET specific surface area by nitrogen adsorption measured by BET method is 30 m ² / g or more, particularly in the range of 50 to 400 m ² / g give good results.

Inorganic fine particles (a) are 0.1 to 8 parts by weight, preferably 0.5 to 100 parts by weight of the non-magnetic toner particles.
It is particularly preferable to use 5 parts by weight, more preferably 1.0 to 3.0 parts by weight.

As the inorganic fine particles (a), those having a number average primary particle diameter of 50 nm or less (more preferably 1 to 30 nm) are used.

The number average primary particle diameter of the inorganic fine particles (a) is
It is a value calculated by magnifying 100,000 times with an electron microscope, randomly selecting 100 particles having a particle diameter of 1 nm or more, measuring their major axis, and obtaining an average value.

If necessary, the inorganic fine particles (a) may be a silicone varnish for the purpose of hydrophobizing and / or controlling the charging property.
Treated with silicone varnish having various functional groups, silicone oil, silicone oil having various functional groups, silane coupling agent, silane coupling agent having various functional groups, and other treatment agents such as organic silicon compounds and organic titanium compounds. It is also preferable. Treatment agents of different types may be used in combination.

In order to maintain a high charge amount and achieve a low consumption amount and a high transfer rate, it is more preferable that the inorganic fine particles (a) are treated with at least silicone oil.

In the present invention, in addition to the above-mentioned inorganic fine particles (a), in addition to the above-mentioned inorganic fine particles (a), a number average primary particle diameter is 50 to 1 in order to improve transferability and / or simultaneous cleaning property during development.
Inorganic or organic spherical particles (b) having a spherical shape of 000 nm (preferably 70 to 900 nm) are externally added.

For example, spherical silica particles and spherical resin particles are preferably used.

The spherical particles (b) preferably have a BET specific surface area of 30 m ² / g or less.

Surface area shape of spherical fine particles (b) Sphericality ψ
Is defined as follows.

[0080]

[Outside 3]

The BET specific surface area can be measured by, for example, QUAN.
When the specific surface area meter Autosorb 1 manufactured by TACHROME is used, the following are examples of measuring methods.

About 0.3 g of true spherical fine particles (b) is weighed in a cell and deaerated at a temperature of 40 ° C. and a vacuum degree of 1.0 × 10 ⁻³ mmHg for 1 hour or more. Then, nitrogen gas is adsorbed in a state of being cooled by liquid nitrogen, and the value is obtained by the multipoint method.

The surface area assuming that the true spherical fine particles (b) are true spheres is the electron micrograph (×) of the true spherical fine particles (b).
Randomly select particles with a particle size of 10 nm or more from 10000)
00 pieces of images of true spherical particles are selected, their diameters are measured, and the value of the averaged diameter is taken as the diameter when the resin particles are assumed to be true spheres. Based on this diameter, the radius γ of the true spherical fine particles is determined, and the surface area (4πγ ² ) of the true spherical fine particles (b) is determined. Furthermore, the volume of spherical particles (b)

[0084]

[Outside 4] Then, the density of the true spherical particles (b) and the weight of the true spherical particles (b) are calculated from the volume. From the obtained surface area and the weight, the surface area (m ² / g) when the true spherical fine particles (b) are assumed to be true spheres is obtained. Since the spherical resin fine particles (b) having a surface area shape sphericity ψ of 0.91 to 1.00 and the inorganic fine particles (a) are externally added in combination, the simultaneous cleaning with development can be favorably carried out for a long period of time. True spherical resin particles (b) are non-magnetic toner particles 10
It is preferable to use 0.01 to 1.0 part by weight, more preferably 0.03 to 0.8 part by weight, per 0 part by weight.

When the true spherical fine particles (b) are true spherical resin fine particles, the resin fine particles can be produced by adjusting production conditions by an emulsion polymerization method, a spray drying method or the like. It is preferably obtained by polymerizing a styrene monomer and a methyl methacrylate monomer by an emulsion polymerization method.
Glass transition point 75 ° C. or higher, more preferably 80 to 150
Resin particles at ℃ show a good effect.

In the present invention, other additives may be used as long as they do not have a substantial adverse effect. Lubricant powders such as Teflon powder, zinc stearate powder, polyvinylidene fluoride powder; abrasives such as cerium oxide powder, silicon carbide powder, strontium titanate powder, calcium titanate powder; anti-caking agent, or carbon black powder, for example. , Zinc oxide powder, tin oxide powder, and other conductivity-imparting agents.

A method for producing the non-magnetic toner particle toner used in the present invention will be described. First, a binder resin, a wax, a metal salt or a metal complex, a pigment as a colorant, a dye, and if necessary, other charge control agents, additives and the like are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill. After that, heat kneading machine such as heating roll, kneader, or extruder is used to melt-knead the resin to make the resins compatible with each other, and then disperse or dissolve the metal compound, pigment, and dye, and after cooling and solidification, crushing and classification. To obtain toner particles. In terms of production efficiency, it is preferable to use a multi-division classifier at the final stage of the classifying process.

The surface treatment for adjusting the obtained toner particles to predetermined values of SF-1 and SF-2 is carried out by pulverizing toner particles dispersed in water and heating them; hot water bath method; passing through hot air stream. Heat treatment method; a mechanical impact method in which mechanical energy is applied to perform the treatment. In the present invention, the thermo-mechanical impact method in which the treatment temperature in the mechanical impact method is the temperature (Tg ± 10 ° C.) around the glass transition point Tg of the toner particles is preferable from the viewpoint of preventing aggregation and productivity.
More preferably, it is carried out at a temperature in the range of the glass transition point Tg ± 5 ° C. of the toner to reduce the pores having a radius of 10 nm or more on the surface, to make the inorganic fine particles (a) work effectively, and to improve the transfer efficiency. Especially effective for.

In the present invention, it is preferable to impart releasability to the surface of the electrostatic latent image bearing member. By this effect, the amount of toner remaining in the transfer can be remarkably reduced, and the transfer residual toner hardly blocks light. Negative ghost images can be essentially prevented, and the efficiency of collecting the transfer residual toner in the developing area at the time of development can be improved, and positive ghost images can be satisfactorily prevented.

Here, a mechanism of generating a ghost image will be described.

Light shielding by the transfer residual toner becomes a particular problem when the surface of the electrostatic latent image carrier is repeatedly used for one transfer material. When the length of one round of the electrostatic latent image carrier is shorter than the length in the traveling direction of the transfer material, charging-exposure-development must be performed in a state where the transfer residual toner is present on the electrostatic latent image carrier. In the image forming method using reversal development, the density is lower than that of the surroundings, as a negative ghost, because the potential of the surface of the electrostatic latent image bearing member where the transfer residual toner is present does not drop sufficiently and the development contrast becomes insufficient. Appears on the image.

On the other hand, if the cleaning effect of the transfer residual toner at the time of development is insufficient, the toner is developed on the surface of the electrostatic latent image bearing member on which the transfer residual toner is present, so that the density of the positive ghost is higher than that of the surroundings. Occurs.

The image forming method of the present invention can favorably prevent the generation of the ghost image.

The present invention is effective when the surface of the electrostatic latent image bearing member is mainly composed of a polymer binder. For example, when a protective film mainly composed of a resin is provided on an inorganic photoreceptor such as selenium or amorphous silicon, or as a charge transport layer of a function-separated type organic photoreceptor, a surface layer composed of a charge transport material and a resin is provided. In this case, the above-mentioned protective layer may be further provided thereon. As means for imparting releasability to such a surface layer, a resin having a low surface energy is used for the resin itself constituting the film, an additive for imparting water repellency and lipophilicity is added, and high releasability is provided. It is possible to pulverize and disperse the material having For example, it can be achieved by introducing a fluorine-containing group or a silicon-containing group into the structure of the resin. For this, a surfactant may be used as an additive. Examples of the powder include powder of a compound containing a fluorine atom (eg, ethylene tetrafluoride, polyvinylidene fluoride, carbon fluoride, etc.). Among these, polytetrafluoroethylene is particularly preferable. In the present invention, it is particularly preferable to disperse the releasable powder such as the fluorine-containing resin in the outermost surface layer.

By these means, the contact angle of water on the surface of the electrostatic latent image bearing member can be set to 85 ° or more (preferably 90 ° or more). If it is less than 85 degrees, deterioration of the toner and the toner carrier due to durability tends to occur.

In order to contain these powders on the surface, a layer in which the powders are dispersed in a binder resin is provided on the outermost surface of the image bearing member, or an organic material mainly composed of a resin is used. In the case of an image carrier, the powder may be dispersed in the uppermost layer without providing a new surface layer.

The amount of the powder added to the surface layer is preferably 1 to 60% by weight, more preferably 2 to 50% by weight, based on the total weight of the surface layer. If the amount is less than 1% by weight, the residual toner after transfer is not sufficiently reduced, the cleaning effect of the residual transfer toner is lowered, and the ghost prevention effect is reduced, and if it exceeds 60% by weight, the strength of the film is lowered, and the image bearing property is reduced. This is not preferable because the amount of light incident on the body is reduced. The particle size of the powder is preferably 1 μm or less, more preferably 0.5 μm or less from the viewpoint of image quality. If it is larger than 1 μm, the line breakage becomes worse due to the scattering of incident light.

The present invention is particularly effective when the charging means is a direct charging method in which the charging member is brought into contact with the image carrier. If there is a large amount of residual toner after transfer, it will directly adhere to the charging member, which is a post-process, causing charging failure. Therefore, the amount of residual toner needs to be smaller than that in corona discharge in which the charging unit does not contact the image carrier.

The present invention provides an image forming method which provides an image having excellent gradation of a graphic image without impairing the reproducibility of isolated dots in the simultaneous cleaning method for development.

As a more desirable form of the present invention, the present inventors have made earnest studies, and then, V _d and (V _d + V _r ) / 2 (V _d : dark part potential, V _r : residual potential) of the photoconductor photosensitive characteristic curve. Is greater than or equal to the exposure intensity at the point where the straight line having a slope of 1/20 with respect to the straight line connecting
It was found that by forming a latent image with an exposure intensity less than 5 times the half-exposure intensity, a reproducibility of isolated dots is good and a graphic image with gradation is obtained in the simultaneous development cleaning method.

The exposure method is not particularly limited, but a laser is preferably used from the viewpoint of reducing the spot diameter and power. When the exposure amount is small, the line portion becomes thin or blurred, and a ghost image cannot be obtained when the amount of light is more than 5 times the half-light amount, but isolated dots are crushed and a graphic image without gradation is not preferable.

V _d and (V _d + V
_r ) / 2, the exposure range which is equal to or higher than the exposure intensity at the point where the straight line having a slope of 1/20 with respect to the slope of the straight line connecting the photoconductor characteristic curve and less than 5 times the half exposure intensity is defined as the half exposure amount. The larger the coefficient (exposure range) / (half-exposure amount) when the unit exposure amount is, the wider the scope of exposure selection and the better the device design. This coefficient is 0.
It is preferably 7 or more, more preferably 1.0 or more.

Further, in the present invention, from the viewpoint of reproducibility of isolated dots, the half-exposure intensity of the photoconductor is 0.
When it is 5 cJ / m ² or less, dot reproducibility is further improved. The reason for this is that the use of such a relatively high-sensitivity photoconductor with respect to the blocking of the exposure of the transfer residual toner reduces the potential fluctuation with respect to the exposure intensity as compared with the relatively low-sensitivity photoconductor. Half-exposure intensity is 0.3 cJ /
More preferable results are obtained at m ² or less.

One of the preferred embodiments of the image carrier used in the present invention will be described below.

Examples of the conductive substrate include metals such as aluminum and stainless steel; aluminum alloy, plastic having a coating layer of indium oxide-tin oxide alloy; paper impregnated with conductive particles, plastic, plastic having conductive polymer, etc. Cylindrical cylinders and films such as

On these conductive substrates, the adhesiveness of the photosensitive layer is improved, the coatability is improved, the substrate is protected, and the defects on the substrate are covered.
An undercoat layer may be provided for the purpose of improving the charge injection property from the substrate and protecting the photosensitive layer against electrical breakdown. The subbing layer is polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymerized nylon, glue,
It is formed of a material such as gelatin, polyurethane, aluminum oxide. The film thickness is usually 0.1 to 10 μm,
It is more preferably 0.1 to 3 μm.

The charge generation layer may be an organic compound such as an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone pigment, a squarylium dye, a pyrylium salt, a thiopyrylium salt or a triphenylmethane dye, or a non-organic compound such as The charge generation material formed of an inorganic material such as crystalline silicon is dispersed in a suitable binder and applied or vapor-deposited. A wide range of binder resins can be selected as the binder. For example, polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacrylic resin, phenol resin, silicone resin, epoxy resin, vinyl acetate resin, etc. may be mentioned. The amount of the binder contained in the charge generation layer is 80% by weight or less, preferably 0-40% by weight. The thickness of the charge generation layer is 5 μm or less, particularly 0.05
˜2 μm is preferred.

The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of charges and transporting them. The charge transport layer is formed by dissolving a charge transport substance in a solvent, if necessary, together with a binder resin, and coating the solution, and the film thickness thereof is generally 5 to 40 μm. As the charge-transporting substance, biphenylene in the main chain or side chain,
Polycyclic aromatic compounds having a structure such as anthracene, pyrene and phenanthrene, nitrogen-containing cyclic compounds such as indole, carbazole, oxadiazole and pyrazoline,
Examples thereof include hydrazone compounds, styryl compounds, and amorphous silicon.

As the binder resin in which these charge transport substances are dispersed, polycarbonate resin, polyester resin,
Resins such as polymethacrylic acid ester, polystyrene resin, acrylic resin and polyamide resin; organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene.

A protective layer may be provided as the surface layer. Examples of the resin for the protective layer include polyester resin, polycarbonate resin, acrylic resin, epoxy resin, phenol resin, and those obtained by curing these resins with a curing agent. These may be used alone or in combination of two or more.

The conductive fine particles in the resin of the protective layer may be dispersed. Examples of the conductive fine particles include metals or metal oxides. Preferred are ultrafine particles formed of zinc oxide, titanium oxide, tin oxide, antimony oxide, isodium oxide, bismuth oxide, tin oxide coated titanium oxide, tin coated indium oxide, antimony coated tin oxide, and zirconium oxide. These can be used alone 2
You may use it in mixture of 2 or more types. Generally, when the particles are dispersed in the protective layer, it is preferable that the particle diameter of the particles is smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles. The particle diameter of the conductive particles or insulating particles dispersed in the protective layer is preferably 0.5 μm or less. The content in the protective layer is 2 to the total weight of the protective layer.
90 wt% is preferable, and 5-80 wt% is more preferable. The thickness of the protective layer is preferably 0.1 to 10 μm, and 1
˜7 μm is more preferred.

The surface layer can be coated by spray coating, beam coating or permeation coating of the resin dispersion liquid.

The preferable conditions of the developing step used in the present invention are that the toner layer on the toner carrying member and the surface of the photosensitive member are in contact with each other at the closest portion, and that the reversal developing method is used.

At this time, during development or during pre-rotation and post-rotation before and after development, a bias of DC or AC component is applied to the photoconductor from the charging member or another member to develop the transfer residual toner on the photoconductor. It is controlled so that the toner can be collected on the toner carrier of the apparatus. The DC component of the bias applied at this time is located between the bright portion potential and the dark portion potential.

At this time, important factors are the charge polarity and the charge amount of the toner on the photoconductor in each step of electrophotography.
For example, when a negatively chargeable photoconductor and a negatively chargeable toner are used to transfer an image visualized by a positive polarity transfer electric field to a transfer material in the transfer process, the type of transfer material (thickness, resistance, dielectric The charge polarity of the transfer residual toner fluctuates from positive to negative due to the relationship between the image area and the like). However, due to the minus when charging the negatively chargeable photoconductor, not only the surface of the photoconductor but also the residual toner of the transfer is uniformly charged to the negative side even if it swings to the positive polarity in the transfer process. It Therefore, the transfer residual toner, which is negatively charged, remains in the bright portion potential portion of the toner to be developed, and the dark portion potential of the toner that should not be developed is:
Due to the developing electric field, the toner is attracted toward the toner carrier, and the toner does not remain on the photoconductor having the dark portion potential.

As a one-component developer, there is also used a method in which a toner is coated on the surface of an elastic roller and the toner is brought into contact with the surface of a photoreceptor to develop the toner. At this time, it is important that the toner layer and the surface of the photoconductor are in contact with each other. At this time, since cleaning is performed at the same time as development by the electric field acting between the photoconductor and the elastic roller facing the surface of the photoconductor via the toner, the surface of the elastic roller or the vicinity of the surface has a potential, and the surface of the photoconductor and the toner carrier There is a need to have an electric field with a narrow gap in the surface. For this reason, the elastic rubber of the elastic roller is resistance-controlled in the medium resistance region to maintain the electric field while preventing conduction with the surface of the photoconductor, or a method of providing a thin insulating layer on the surface layer of the conductive roller can be used. . Further, it is also possible to adopt a configuration in which a conductive resin sleeve in which the side facing the surface of the photoconductor is coated with an insulating material is provided on the conductive roller, or a conductive layer is provided on the side not facing the photoconductor with the insulating sleeve.

When the one-component contact developing method is used, the peripheral surface of the roller carrying the non-magnetic toner and the peripheral speed of the photosensitive member may rotate in the same direction or may rotate in the opposite direction. When the rotations are in the same direction, the peripheral speed ratio to the peripheral speed of the photoconductor is preferably 100% or more. If it is less than 100%,
Image quality is degraded. As the peripheral speed ratio is increased, the amount of the non-magnetic toner supplied to the developing portion is increased, the frequency of toner desorption with respect to the electrostatic latent image is increased, and unnecessary portions are scraped off and applied to necessary portions. By repeating the above, an image faithful to the electrostatic latent image can be obtained. From the viewpoint of simultaneous cleaning during development, the effect of physically peeling off the transfer residual toner adhered on the photoconductor from the photoconductor surface and the toner adhesion part by the peripheral speed difference and recovering it by the electric field can be expected. The higher the value, the more convenient the recovery of the transfer residual toner.

In the present invention, it is preferable in view of environmental protection that the charging member is in contact with the surface of the electrostatic latent image bearing member such as the photoconductor so that ozone is not generated.

The image forming method of the present invention will be described with reference to the accompanying drawings.

Next, the image forming method of the present invention will be specifically described with reference to the drawings.

In FIG. 1, reference numeral 100 denotes a photosensitive drum around which a primary charging roller 117 which is a contact charging means,
Developing device 140, which is a developing means, and transfer charging roller 11
4, a register roller 124 is provided. Then, the photosensitive drum 100 is charged to, for example, −700 V by the primary charging roller 117. Bias applying means 131
The DC voltage of the applied voltage is, for example, -1350V. Then, the laser light 123 is irradiated onto the photosensitive drum 100 by the laser generator 121 to be exposed to form a digital electrostatic latent image. Photosensitive drum 1
The electrostatic latent image on 00 is developed with a non-magnetic one-component toner by the developing device 140, and is transferred via the transfer agent 127 to the photosensitive drum 1.
The transfer material 1 is transferred by the transfer roller 114 to which a bias voltage is applied by the bias applying means 134 abutted against
Transferred onto 27. The transfer material 127 on which the toner image 129 is placed is conveyed by a conveyor belt 125 to a heat and pressure fixing device having a heating roller 128 and a pressure roller 126, and is fixed on the transfer material.

The charging roller 117 has a central core metal 117.
The basic structure is b and the conductive elastic layer 117a having the outer periphery thereof. The charging roller 117 is pressed against the surface of the photoconductor 100 with a pressing force, and rotates in the counter direction as the photoconductor 100 rotates.

A preferable process condition when the charging roller is used is that the contact pressure of the roller is 5 to 500 g / c.
In m, when a DC voltage superimposed with an AC voltage is used, AC voltage = 0.5 to 5 kVpp, AC frequency = 50
Hz to 5 kHz, DC voltage = ± 0.2 to ± 1.5 kV, and when DC voltage is used, DC voltage = ± 0.2 to
± 5 kV.

The material of the charging roller as the contact charging means is preferably conductive rubber, and a release film may be provided on the surface thereof. As the release film, nylon resin, PVDF (polyvinylidene fluoride), PVDC
(Polyvinylidene chloride) is applicable.

The developing device 140 is in contact with the photosensitive drum 100 as shown in FIGS. 1 and 2, and the core metal 104a and the elastic layer 10 to which the bias is applied by the bias applying means 133.
Toner carrier 104 composed of an elastic roller having 4b
(Hereinafter referred to as a developing sleeve) is provided. Developing device 14
A toner applying roller 141 having a core metal 141a to which a bias is applied by the bias applying means 132 and an elastic layer 141b is disposed in the position 0. Developing sleeve 104
As a member that regulates the amount of toner that adheres to and is transported,
The toner regulating blade 103 is provided, and the contact pressure of the toner regulating blade 103 against the developing sleeve 104 controls the amount of toner conveyed to the developing area. In the developing area, at least a DC developing bias is applied to the developing sleeve 104, and the toner on the developing sleeve is transferred onto the photosensitive drum 100 according to the electrostatic latent image to form a toner image.

In order to carry out simultaneous development cleaning, when the light portion potential of the photosensitive drum 100 is 0 to 250 V and the dark portion potential is 300 to 100 V, the bias voltage applied by the bias applying means 132 is 10.
It is preferable that the bias voltage is 0 to 900V, and the bias voltage applied by the bias applying unit 133 is 100 to 900V. Further, the bias voltage applied by the bias applying means 132 is 10 to 400 V in absolute value as compared with the bias voltage applied by the bias applying means 132.
The larger one is the developing sleeve 104 of the non-magnetic toner 142.
It is preferable since the non-magnetic toner can be smoothly removed from the developing sleeve 104.

With respect to the rotating direction of the developing sleeve 104,
The toner application roller 141 is preferably rotated in the counter direction from the viewpoint of supplying and stripping the non-magnetic toner.

The toner image formed on the photosensitive drum 100 is transferred onto the transfer material by the transfer means, with or without the intermediate transfer member. FIG. 1 shows an example in which the toner image is transferred to the transfer material 127 without passing through the intermediate transfer body. In the transfer process in FIG. 1, the toner image is transferred by the contact transfer process.

In the contact transfer step, the toner image is electrostatically transferred onto the transfer material 127 while the transfer means is in contact with the photosensitive drum 100, which is an electrostatic latent image carrier, via the transfer material (127). The contact pressure of the transfer means is a linear pressure of 2.9 N / m.
It is preferably (3 g / cm) or more, more preferably 19.6 N / m (20 g / cm) or more. When the linear pressure as the contact pressure is less than 2.9 N / m (3 g / cm), the transfer deviation of the transfer material and the transfer failure are likely to occur. A transfer roller or a transfer belt is used as the contact transfer means.

In the transfer step shown in FIGS. 1 and 4, the transfer roller 114 having the core metal 114a to which the bias voltage is applied by the bias applying means 134 and the conductive elastic layer 114b is used as the transfer means.

The conductive elastic layer is made of urethane or EPDM in which a conductive material such as carbon is dispersed, and has a volume resistance of 10 ⁶ to 10 ^6.
It is preferably made of an elastic body of ¹⁰ Ω · cm.

The contact transfer means is particularly effectively used for an image forming apparatus having a small diameter photosensitive drum having a diameter of 50 mm or less. This is because in the case of a small-diameter photosensitive drum, the curvature with respect to the same linear pressure is large, and the pressure is likely to be concentrated at the contact portion. It is considered that the same phenomenon occurs in the belt photoreceptor, and it is also effective for an image forming apparatus having a belt photoreceptor having a radius of curvature of 25 mm or less at the transfer portion.

In the image forming method of the present invention, SF-1 of the non-magnetic toner is 120 to 160, and SF-2 is SF-2.
In the non-magnetic toner having a weight average particle diameter of 4 to 9 μm, the inorganic fine particles (a) having a primary number average particle diameter of 50 nm or less and the primary number average diameter of 50 to 10
The true spherical fine particles (b) having a surface area shape sphericity ψ of 0.91 to 1.00 are externally added to the surface of the non-magnetic toner particles to exhibit a good transfer rate.

The transfer residual toner after the transfer process is the charging roller 1.
The transfer residual toner that has been conveyed to the installation position of 17 and has passed through the charging roller 117 is collected in the developing device 140 by cleaning at the same time as the development in the developing device 140. At that time, since the inorganic fine particles (a) and the true spherical particles (b) are externally added to the non-magnetic toner particles, the non-magnetic property of the developing sleeve 104 rotating with respect to the rotating photosensitive drum 100. Under the condition that the toner layer is pressed, the electrostatic latent image can be developed and the transfer residual toner can be smoothly collected from the photosensitive drum 100 at the same time, and the durability of many sheets is excellent.

The present invention can be satisfactorily implemented in an image forming method using a contact charging member and a photoconductor having a charge injection layer and performing a simultaneous development cleaning system. A preferred example will be described with reference to FIGS.

In the image forming method shown in FIG. 5, the photosensitive drum 100, which is a photosensitive member, has a charge injection layer on its surface, and has a layer structure as shown in FIG. 8, for example. The photosensitive drum 100 is charged by the contact charging member to which a bias voltage is applied. Although the contact charging member may be a blade-shaped member, a rotatable roller-shaped member, a rotatable brush-roller-shaped member, or a rotatable belt-shaped member may be cleaned in order to properly set the peripheral speed difference with the photosensitive drum 100. It is preferable as a charging step in a pressureless system or a simultaneous development cleaning system. FIG. 5 shows an example of a contact charging member composed of a magnetic brush roller 117a to which a bias voltage is applied by the bias applying means 131a.

Also in the image forming method shown in FIG. 5, according to the present invention, when the contact angle of water on the surface of the photoconductor is 85 degrees or more (preferably 90 degrees or more), the surface of the photoconductor is demolded. Property, and the effect of improving the transferability of the toner in the transfer step can significantly reduce the amount of transfer residual toner. Further, there is almost no shading due to the transfer residual toner, and the negative ghost image can be essentially prevented, and the cleaning efficiency of the transfer residual toner at the time of development can be improved, and the posi ghost image can be excellently prevented.

The photoconductor having a charge injection layer is made to have a good charge injection charge by applying a DC voltage so that the charge polarity of the transfer residual toner is aligned, and the charge efficiency is close to the charge potential of the photoconductor (charge by DC discharge). (Compared to (1)), the transfer residual toner is controlled without being excessively charged. Therefore, it is possible to more favorably suppress the charge-up of the toner, the broadening of the charge amount distribution of the toner, and the like due to the residual toner remaining on the transfer being collected on the toner carrier during development.

More preferably, the applied voltage applied to the contact charging member is V, the potential of the photosensitive member immediately before contact with the contact charging member is VD, and the distance between the voltage applying portion of the contact charging member and the photosensitive member is d. In this case, preferably, the dynamic resistance of the photosensitive body having the charge injection layer whose surface has a volume resistance value of 1 × 10 ⁸ to 10 ¹⁵ Ω · cm, which is brought into contact with the substrate of the rotating body of the conductor. The volume resistance value in the measuring method is
The higher electric field of either (V-VD) / d or V / d is V
1 (V / cm), in the applied electric field range of 20 to V1 (V / cm), 10 ⁴ Ω · cm to ^{10 10} Ω · cm
A charging step of contacting the contact charging member in the range to apply a voltage to perform charging is preferable.

By adopting the structure using the contact charging member and the photoconductor, the charging start voltage Vh is small and almost 90% of the voltage applied to the charging member is the photoconductor charging potential.
It is possible to charge up to at least%. For example, when a DC voltage of 100 to 2000 V in absolute value is applied to the contact charging member, the charging potential of the electrophotographic photosensitive member having the charge injection layer is charged to a value of 80% or more, further 90% or more of the applied voltage. be able to. On the other hand, the charging potential of the photoconductor obtained by the conventional charging using discharge is almost 0 V when the applied voltage is 640 V or less, and when the applied voltage is 640 V or more, only a charging potential of a value obtained by subtracting 640 V from the applied voltage is obtained. It was not there.

The charge injection layer is 1 × 10 ⁸ Ω · cm to 1 ×
By having 10 ¹⁵ Ω · cm, image deletion in a high humidity environment can be favorably prevented, and injection charging by the contact charging member can be favorably performed. The charge injection layer has a volume resistance value of 1 ×
It is preferably 10 ¹¹ Ω · cm to 1 × 10 ¹⁴ Ω · cm, and more preferably 1 × 10 ¹² Ω · cm to 1 × 10 ¹⁴ Ω · cm.

The charge injection layer is composed of a conductive fine particle dispersion layer in which conductive fine particles are dispersed in a binder resin, and the conductive fine particle dispersion layer is a dip coating method, a spray coating method, a roll coating method, or a beam coating method. It is formed by applying a suitable coating method such as a construction method. It may be formed by mixing or copolymerizing an insulating binder with a resin having high light transmittance and ion conductivity, or may be formed by a medium resistance and photoconductive resin alone. In the case of the conductive fine particle dispersed layer, the addition amount of the conductive fine particles is 10
2 to 250 parts by weight, further 2 to 190 parts by weight relative to 0 parts by weight
It is preferably part by weight. When the amount is less than 2 parts by weight, it is difficult to obtain a desired volume resistance value, and when the amount is more than 250 parts by weight, the film strength is lowered and the charge injection layer is easily scraped off, and the life of the photoreceptor is shortened. This is because the resistance tends to be low, and the resistance tends to be low, so that an image defect due to the flow of the latent image potential is likely to occur.

The binder resin for the charge injection layer may be the same as the binder resin for the lower layer, but in this case, the coating surface of the charge transport layer may be disturbed when the charge injection layer is coated. Therefore, it is necessary to particularly select the coating method.

The charge injection layer preferably contains a lubricating powder. The reason is that the friction between the photoconductor and the injection charging member is reduced during charging, so that the charging nip is enlarged and the charging characteristics are improved. In particular, it is more preferable to use a fluororesin, a silicone resin, or a polyolefin resin having a low critical surface tension as the lubricating powder. More preferably, tetrafluoroethylene resin (PTFE) is used. In this case, the addition amount of the lubricating powder is 1
The amount is preferably 2 to 50 parts by weight, more preferably 5 to 40 parts by weight, based on 00 parts by weight. If it is less than 2 parts by weight, the amount of the lubricating powder is not sufficient, so that the charging characteristics are not sufficiently improved, and if it exceeds 50 parts by weight, the resolution of the image and the sensitivity of the photoreceptor are lowered.

The thickness of the charge injection layer is preferably 0.1 to 10 μm, more preferably 1 to 7 μm.

It is preferable to inject charges to the surface of the photoconductor having a medium resistance surface resistance with a medium resistance contact charging member,
More preferably, the charge is not injected into the trap potential of the surface material of the photoconductor, but the conductive fine particles in the charge injection layer in which the conductive fine particles are dispersed in the light-transmitting and insulating binder resin are charged with electric charge. Charge.

Concretely, it is based on the theory that a contact charging member charges a minute capacitor having a charge transport layer as a dielectric and an aluminum support and conductive fine particles in a charge injection layer as both electrode plates. Is. At this time, the conductive fine particles are electrically independent from each other and form a kind of minute float electrode. For this reason, the surface of the photoconductor looks macroscopically charged and charged to a uniform potential.
Actually, the situation is such that a myriad of charged conductive fine particles cover the surface of the photoconductor. For this reason,
Even if image exposure is performed by a laser, each conductive fine particle is electrically independent, so that an electrostatic latent image can be held.

Therefore, the charge injection property and the charge retention property are improved by substituting the conductive fine particles for the trap levels which existed on the surface of the conventional photoconductor in a small amount.

Here, the method of measuring the volume resistance value of the charge injection layer is as follows. A charge injection layer is formed on a polyethylene terephthalate (PET) film having a conductive film vapor-deposited on its surface, and this is measured by a volume resistance measuring device (Hewlett Packard). Company 4
The measurement is performed by applying a voltage of 100 V in an environment of 23 ° C. and 65% with a 140 B pAMASTER).

A method for measuring the dynamic resistance of the contact charging member will be described with reference to FIG. In FIG. 6, a charging roller means 117a having a magnetic brush of magnetic particles is used as a contact charging member. The dynamic resistance of the charging roller means is measured in an environment of a temperature of 23 ° C. and a humidity of 65% RH.

Aluminum drum 2 which is a conductive substrate and sleeve 1 having a gap 4 of 0.5 mm 1
a has a fixed magnet 1-a inside, and a magnetic brush 7 made of magnetic particles is attached with a charging roller means 117a so that the nip 3 with the aluminum drum 2 becomes 5 mm, and rotation when actually forming an image is performed. Sleeve 1 in speed and direction of rotation
a is rotated with the aluminum drum, a DC voltage 6 is applied to the charging roller means 117a, and the current flowing in the system is measured by an ammeter 5 to obtain resistance, and further, the gap 4, the nip 3 and the magnetic particles are measured. The dynamic resistance is calculated from the width in contact with the aluminum drum.

The resistance value of the charging member generally varies depending on the applied electric field applied to the charging member, and the behavior is such that the resistance is low particularly in a high applied electric field and high in a low applied electric field. Existence is recognized.

When charging is performed by injecting charges into the photoconductor, the surface to which the photoconductor is charged has rushed into the nip portion between the photoconductor and the charging member (upstream side from the charging member). In this case, there is a large voltage difference between the charging potential of the photosensitive member before the rush and the voltage applied to the charging member, and therefore the applied electric field applied to the charging member becomes high. However, as the photoconductor passes through the nip portion, charges are injected into the photoconductor, and the charging is gradually performed in the nip portion, so that the potential on the photoconductor gradually changes to the applied voltage applied to the charging member. , The difference between the applied voltage applied to the voltage application portion and the potential on the photoconductor is small, and the difference approaches 0 V, so that the applied electric field applied to the charging member becomes smaller accordingly. The applied electric field applied to the charging member in the step of charging the photoconductor is different between the upstream side and the downstream side of the nip portion of the charging member, and the applied electric field applied to the charging member is high on the upstream side.
It is low on the downstream side.

Therefore, when the step of removing charges such as pre-exposure is performed before the charging step, the potential on the photosensitive member when it enters the nip portion of the charging member is almost 0V,
The applied electric field on the upstream side is almost determined by the applied voltage applied to the charging member, but if such a step of removing the charges is not provided, it depends on the applied voltage and polarity of the charging and transfer, that is, after the transfer. It is determined by the potential on the body and the applied voltage applied to the charging member.

When charging is performed by injecting electric charges onto the photosensitive member, the resistance value of the charging member is 1 × 10 ⁴ Ω · cm to 1 × 10 ¹⁰ Ω · cm in an applied electric field at a certain point. Even within the range, for example, an applied electric field of 0.3 × V / d at an applied voltage of 30% of the applied voltage to the charging member.
If the resistance is 1 × 10 ¹⁰ Ω · cm or more in the range of (V / cm) or less, the charging due to the injection at the downstream side of the nip portion of the charging member is significantly reduced, and the applied voltage is 7
The charge up to 0% is good, but the remaining 30% has a low charge injecting property, making it difficult to inject the charge onto the photoconductor and difficult to charge to a desired potential. That is, the resistance value under application of a lower electric field has a great influence on the property of injecting charges into the photoconductor.

Therefore, in the dynamic resistance measuring method in which the contact charging member is brought into contact with the rotating conductive substrate, the volume resistance value is measured as (V-VD) / d or V / d, whichever is higher. When V1 (V / cm), the applied electric field range is 20
(V / cm) and V1 (V / cm) as low as 1 × 1
It is important to use a contact charging member in the range of 0 ⁴ Ω · cm to 1 × 10 ¹⁰ Ω · cm, and a potential almost equal to the applied voltage can be obtained on the photoconductor.

From the viewpoint that a good image can be formed when the potential on the photoreceptor is up to about 80% of the applied voltage,
1 × 10 ⁴ Ω · cm in the applied electric field range V3 to V1 (V / cm) when the electric field of 2 × V / d is V3 (V / cm)
A contact charging member in the range of 1 × 10 ¹⁰ Ω · cm may be used. In the simultaneous development cleaning or cleanerless image forming method, when a potential difference of a certain level or more (about 50 V or more according to the knowledge of the present inventors) occurs between the potential on the photoconductor and the potential (applied voltage) of the contact charging member, charging is performed. The transfer residual toner, which is controlled to have a regular charging polarity in the member, gradually leaks from the charging member during image formation, so it is important to keep the potential difference within a range where negative memory due to image exposure light blocking does not occur. .

On the other hand, if the applied voltage applied to the charging member has an applied electric field of less than 1 × 10 ⁴ Ω · cm, an excessive leakage current from the contact charging member is caused by scratches, pinholes, etc. generated on the surface of the photosensitive member. Easily flows into the surrounding area, causing poor charging around the area, enlargement of pinholes, and electrical breakdown of the charging member. Since the conductive layer (metal substrate) of the photoconductor is exposed on the surface of the photoconductor, the potential on the photoconductor is 0 V, and therefore the maximum applied electric field applied to the charging member is not applied to the charging member. It is determined by the applied voltage applied.

Even if the resistance value of the charging member is controlled to be in the range of 1 × 10 ⁴ Ω · cm to 1 × 10 ¹⁰ Ω · cm at an applied electric field at one point, the charging failure or the voltage resistance may be poor. That's what it means.

Therefore, in order to charge the photoconductor, the maximum electric field applied to the charging member, that is, the application determined by the voltage difference between the photoconductor potential on the upstream side of the nip portion of the charging member and the applied voltage applied to the charging member. The higher applied electric field of the electric field or the applied electric field determined by the applied voltage applied to the charging member when a pinhole exists due to a pre-exposure step or a scratch on the photoconductor is V1 (V
/ Cm) applied electric field range 20 to V1 (V / c)
m), the resistance value is 1 × 10 ⁴ Ω · cm to 1 × 10 ¹⁰ Ω ·
It is preferably in the range of cm.

As the nip width between the charging member and the photosensitive member is increased, the contact area between the charging member and the photosensitive member is increased, and the contact time is also increased. Good charging is achieved. In order to obtain sufficient charge injection properties even if the nip width is narrowed, the resistance value of the charging member is
Within the range of the applied electric field, R1 / R2 ≦ 10 where R1 is the maximum resistance value and R2 is the minimum resistance value due to the applied electric field.
It is preferably in the range of 00. In the process of charging in the nip, the resistance changes abruptly,
This is because the injection of electric charges into the photoconductor does not follow and the charges may pass through the nip portion, so that sufficient charging may not be performed.

In the combination of the contact charging member and the photosensitive member having no injection charging layer, the effect of aligning the charging of the toner with the regular charging polarity of the toner is not sufficient in AC discharge.
In DC discharge, the toner is charged to a regular toner charging polarity, but the toner is likely to be excessively charged, which may adversely affect development. On the other hand, by the configuration using the photoconductor having the injection charging layer and the contact charging member, the charge of the transfer residual toner is adjusted to the regular toner charging polarity, and the charge amount is appropriately controlled. It is possible to provide an image forming method which is excellent in recoverability of the toner and has stable repeating characteristics of development.

It is preferable that the triboelectric charging polarity of the contact charging member with respect to the photoconductor is the same as the charging polarity of the photoconductor. According to the knowledge of the present inventors, the charging potential of the photoconductor in the charging step by charge injection is the injection property plus the frictional charge of the contact charging member with the photoconductor. If the triboelectrification polarity of the contact charging member with respect to the photoconductor is opposite to the electrification polarity of the photoconductor, the photoconductor potential is reduced by the amount of triboelectric charge, thereby causing a potential difference between the contact charging member and the photoconductor surface. Although the decrease in the photoreceptor potential due to triboelectric charging is up to several tens of volts,
Due to this electric field, the collection and retention properties of the transfer residual toner of the contact charging member are deteriorated, and when the contact charging member is composed of magnetic particles or the like, transfer to the photoconductor is likely to occur and cause a positive ghost or fog.

It is preferable that the contact charging member moves with a peripheral speed difference with respect to the photosensitive member. By making the moving speed of the peripheral speed surface of the contact charging member and the moving speed of the surface of the photoconductor different from each other, charging stability can be obtained for a long period of time while maintaining the long life of the photoconductor and the long life of the charging roller. Can be achieved at the same time, and highly stable charging and long life of the image forming system can be achieved. Toner easily adheres to the surface of the contact charging member, and this adhered toner tends to hinder the charging. By making the surface moving speed of the photoconductor and the surface moving speed of the contact charging member different, Since it is possible to supply substantially more surface of the contact charging member, it is possible to obtain the effect of inhibiting charging. When the transfer residual toner reaches the charged portion, the toner having a small adhesion to the photoconductor moves toward the charging member due to the electric field, and the resistance of the surface of the charging member locally changes, so that the discharge path is blocked. Therefore, the problem that the electric potential is less likely to be applied to the surface of the photoconductor and, as a result, defective charging occurs is effectively eliminated.

From the viewpoint of simultaneous development and cleaning,
Due to the difference in peripheral speed between the contact charging member and the photoconductor, the effect of physically peeling off the surface of the photoconductor and the toner adhesion part and improving the efficiency of collection by the electric field can be expected, and the residual toner after transfer can be made higher. It is possible to efficiently control the charge and measure the improvement of the recoverability in the development.

When a speed difference is provided between the surface of the photosensitive member and the surface of the contact charging member, the contact angle of the surface of the photosensitive member is set to 85 in order to prevent abrasion or contamination of the surface of the photosensitive member or the surface of the contact charging member due to the sliding effect of each other. A photoconductor of more than one degree is effective.

When the photosensitive member surface moving speed and the contact charging member surface moving speed are made different, preferably, when the photosensitive member surface moving speed is V and the roller surface moving speed is v at the contact portion between the photosensitive member and the roller. , V / V having an absolute value of 1.1 or more, that is, 110% or more, a stable charging property can be obtained, and the recovery of the transfer residual toner during development can be improved.

One of the preferred embodiments of the present invention is to use magnetic particles for the contact charging member. Further, it is preferable that the conductive magnetic particles have a volume resistance value of 10 ⁴ Ω · cm to 10 ⁹ Ω · cm controlled in the resistance range.

When the average particle size of the magnetic particles is 5 to 200 μm, it is difficult for the magnetic particles to adhere to the photoreceptor,
The density of the magnetic brush spikes on the sleeve can be made dense,
The injection chargeability to the photoconductor is improved. More preferably, the average particle size is 10 to 100 μm, and within this particle size range, the transfer residual toner on the photoconductor is scraped off efficiently,
This is preferable because the toner can be temporarily held in the magnetic brush because it is efficiently electrostatically taken into the magnetic brush and the charging of the toner is surely controlled. Furthermore, the median diameter of the magnetic particles is more preferably 10 to 50 μm.

The median diameter of the magnetic particles was determined by using a laser diffraction particle size distribution measuring device HEROS (manufactured by JEOL Ltd.).
Magnetic particles having a particle diameter of 0.05 to 200 μm are measured on a volume basis. At that time, the range of 0.05 μm to 200 μm is divided into 32 logarithms and divided into 32 channels, the number of particles in each channel is measured, and the 50% diameter is determined as the median diameter from the measurement result.

The use of these magnetic particles in the contact charging member is advantageous in that the number of contact points with the photoconductor is remarkably increased and a more uniform charging potential is given to the photoconductor. Further, it is also advantageous in that the magnetic particles that are in direct contact with the photoconductor are replaced by the rotation of the magnetic brush, and the deterioration of the charge injection property due to the dirt on the surface of the magnetic particles can be significantly reduced.

The gap between the holding member holding the magnetic particles and the photoconductor is preferably in the range of 0.2 to 2 mm. If the diameter is less than 0.2 mm, it becomes difficult for the magnetic particles to pass through the gap, and the magnetic particles are not smoothly transported on the holding member, resulting in poor charging or excessive accumulation of magnetic particles in the nip portion, resulting in adhesion to the photoconductor. It will be easier. If it is larger than 2 mm, it is difficult to form a wide nip width between the photoconductor and the magnetic particles, which is not preferable. More preferably 0.2 to 1 mm, further 0.3 to 0.7 mm
Is preferred.

In the present invention, the contact charging member has a magnet for holding the magnetic particles, the magnetic flux density B (T: Tesla) of the magnetic field generated by the magnet, and the magnetic particles within the magnetic flux density B. Maximum magnetization σ _B (Am ² / k
It is more preferable to set each value such that g) satisfies the following relational expression.

B · σ _B ≧ 4 When the above expression is satisfied, the magnetic force acting on the magnetic particles is appropriate, the holding force of the contact charging member to the magnetic particles is sufficient, and the magnetic particles are less likely to transfer to the photoreceptor.

The magnetic particles used for injection charging include:
In order to make the magnetic brush stand by the magnetism and bring this magnetic brush into contact with the photoconductor to be charged, an alloy or compound containing an element exhibiting ferromagnetism such as iron, cobalt, or nickel, or an oxidation treatment or a reduction treatment is performed to make the resistance. Examples include ferrite whose value is adjusted and hydrogen-reduced Zn—Cu ferrite. In order to keep the resistance value of the ferrite within the above range in the range of the applied electric field or less as described above, it can also be achieved by adjusting the composition of the metal constituting the flight. In general, when the amount of metal other than divalent iron increases, the resistance decreases, and the resistance is likely to suddenly decrease.

The triboelectrification polarity of the magnetic particles is preferably not opposite to the electrification polarity of the photoreceptor. As described above, the decrease in the charging potential of the photoconductor due to the triboelectric charge causes a force in the direction of transfer of the magnetic particles to the photoconductor, so that the condition for holding the magnetic particles on the contact charging member becomes more severe. As a method of controlling the triboelectrification polarity of the magnetic particles, a method of surface-treating the magnetic particles can be mentioned.

As a surface treatment method of the magnetic particles, there is a method of coating the surface of the magnetic particles with a vapor deposition film, a conductive resin film, a conductive pigment-dispersed resin film or the like. This surface layer does not necessarily have to completely cover the magnetic particles, and the magnetic particles may be exposed within a range in which the effect of the present invention can be obtained. The surface layer may be formed discontinuously.

From the viewpoint of productivity and cost of magnetic particles, it is preferable to coat the conductive pigment-dispersed resin film.

Further, from the viewpoint of suppressing the electric field dependence of the resistance value, it is preferable to coat a resin film in which a high resistance binder resin is dispersed with an electron conductive conductive pigment.

It is important that the resistance of the magnetic particles after coating is within the above range. Further, from the viewpoint of widening the allowable range of abrupt resistance drop on the high electric field side, the size of scratches on the photoconductor, and the generation of leak images due to depth, the resistance of the base magnetic particles is also within the above range. It is preferable.

Examples of the binder resin used for coating the magnetic particles include vinyl resin, polycarbonate, phenol resin, polyester, polyurethane, epoxy resin, polyolefin, fluororesin, silicone resin and polyamide. Particularly, from the viewpoint of preventing toner contamination, a resin having a small critical surface tension is preferable. For example, polyolefin, fluororesin, and silicone resin are more preferable.

Further, from the viewpoint of maintaining a wide allowable range for preventing a leak image due to a resistance drop on the high electric field side and a scratch on the photoconductor, the resin coated on the magnetic particles is preferably a silicone resin having a high voltage resistance.

As the fluororesin, polyvinyl fluoride,
Examples thereof include polyvinylidene fluoride, polytrifluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, polytetrafluoroethylene and polyhexafluoropropylene.

Further, a solvent-soluble copolymer obtained by copolymerizing a fluorine-containing monomer which produces these fluororesins with another monomer can be mentioned.

As the silicone resin, KR271, KR282, KR311, KR25 manufactured by Shin-Etsu Silicone Co., Ltd.
5, KR155 (straight silicone varnish), KR
211, KR212, KR216, KR213, KR2
17, KR9218 (modified silicone varnish), SA
-4, KR206, KR5206 (Silicone alkyd varnish), ES1001, ES1001N, ES10
02T, ES1004 (silicone epoxy varnish),
KR9706 (Silicone acrylic varnish), KR52
03, KR5221 (silicone polyester varnish); SR2100, SR210 manufactured by Toray Silicone Co., Ltd.
1, SR2107, SR2110, SR2108, SR
2109, SR2400, SR2410, SR241
1, SH805, SH806A, SH840.

The conductive fine particles dispersed in the binder resin for coating include metals such as copper, nickel, iron, aluminum, iron and silver; iron oxide, ferrite, zinc oxide, tin oxide, antimony oxide and titanium oxide. Metal oxides; electroconductive conductive powders such as carbon black. Further, examples of the ion conductive agent include lithium perchlorate and quaternary ammonium salts.

In the image forming method shown in FIG. 5, the steps after the charge injection charging step may be performed under the same conditions as in the image forming method shown in FIG.

Production Example 1 of non-magnetic toner Polyester resin (weight average molecular weight 200,000; low molecular weight side peak: about 7,000; glass transition point Tg 63 ° C.) 100 parts by weight carbon black 7 parts by weight Iron complex of monoazo dye (negative charging property) Control agent) 2 parts by weight Low molecular weight polypropylene (release agent) 2 parts by weight The above materials are mixed in a blender, melted and kneaded in a twin-screw extruder heated to 130 ° C., and the cooled kneaded material is roughly crushed by a hammer mill. Then, the coarsely pulverized product was finely pulverized by a jet mill, and the obtained finely pulverized product was strictly classified by a multi-division classifier using a Coanda effect to obtain non-magnetic toner particles.

The shape factor S of the obtained non-magnetic toner particles
F-1 was 163 and SF-2 was 155.

The obtained non-magnetic toner particles were subjected to a surface treatment by a thermomechanical impact force (treatment temperature 60 ° C.) using a surface modification device (Hybridizer manufactured by Nara Machinery Co., Ltd.) to obtain a shape. The coefficient SF-1 is 145 and SF-2 is 1.
22 non-magnetic toner particles were obtained. SF-1 and SF-2
To 100 parts by weight of the non-magnetic toner particles having a reduced particle size, hydrophobic dry silica fine particles hydrophobically treated with dimethyl silicone oil and hexamethyldisilazane (primary number average particle diameter 12 nm; BET specific surface area 120 m ² / g)
1.8 parts by weight and true spherical polymethylmethacrylate fine particles (surface area sphericity ψ = 0.99; primary number average particle diameter 400 nm; BET specific surface area 15 m ² / g; glass transition temperature 125 ° C .; weight average molecular weight 300,000). ) 0.3 part by weight was externally added to obtain a non-magnetic toner (A).

The obtained non-magnetic toner (A) had a weight average particle diameter of 6.6 μm, a number average particle diameter of 5.4 μm, SF-1 of 152 and SF-2 of 134. there were. The toner particle size was measured using a Coulter Counter Multisizer (manufactured by Coulter). Table 1 shows the physical properties of the non-magnetic toner (A).

Production Example 2 of Non-Magnetic Toner Styrene / butyl acrylate / butyl maleate half ester copolymer (weight average molecular weight 300,000; low molecular weight side peak: about 10,000; glass transition point Tg: 62 ° C) 100 parts by weight carbon black 7 parts by weight Iron complex of monoazo dye (negative charge control agent) 2 parts by weight Low molecular weight polypropylene (release agent) 2 parts by weight The above materials are mixed by a blender and melt-kneaded by a twin-screw extruder heated to 130 ° C. Then, the cooled kneaded product is roughly crushed with a hammer mill, the coarsely crushed product is finely crushed with a jet mill, and the resulting finely crushed product is strictly classified with a multi-division classifier using the Coanda effect to make it non-magnetic. Toner particles are obtained.

The shape factor S of the obtained non-magnetic toner particles
F-1 was 157 and SF-2 was 150.

The obtained non-magnetic toner particles were subjected to a surface treatment by a thermomechanical impact force (treatment temperature 64 ° C.) using the above-mentioned surface modification device, and the shape factor SF-1 was 152,
SF-2 130 non-magnetic toner particles were obtained. SF-1
And 100 parts by weight of the non-magnetic toner particles with reduced SF-2, hydrophobic dry silica fine particles (primary number average particle size 8 n
m; BET specific surface area 100 m ² / g) 1.8 parts by weight and true spherical polymethylmethacrylate fine particles (surface area sphericity ψ = 0.97; primary number average particle diameter 400 nm; B
ET specific surface area 15 m ² / g; glass transition temperature 128 ° C .;
A nonmagnetic toner (B) was obtained by externally adding 0.3 part by weight of a weight average molecular weight of 350,000).

The obtained non-magnetic toner (B) had a weight average particle diameter of 6.8 μm, a number average particle diameter of 5.9 μm, SF-1 of 152 and SF-2 of 131. there were.

Table 1 shows the physical properties of the obtained non-magnetic toner (B).

Production Example 3 of Nonmagnetic Toner : Instead of the true spherical polymethylmethacrylate fine particles, true spherical silica fine particles (surface area shape sphericity ψ = 0.99; primary number average particle diameter 100 nm; BET specific surface area 20 m ² /
A non-magnetic toner (C) was obtained in the same manner as in Production Example 1 except that 0.5 part by weight of g) was used.

Table 1 shows the physical properties of the thus-obtained non-magnetic toner (C).

Production Example 4 of non-magnetic toner In place of the true spherical polymethylmethacrylate fine particles, true spherical silica fine particles (surface area shape sphericity ψ = 0.98; primary number average particle diameter 100 nm; BET specific surface area 20 m ² /
A non-magnetic toner (D) was obtained in the same manner as in Production Example 2 except that 0.5 part by weight of g) was used.

Table 1 shows the physical properties of the obtained non-magnetic toner (D).

Production Example 5 of Nonmagnetic Toner A comparative nonmagnetic toner (i) was obtained in the same manner as in Production Example 1 except that the true spherical polymethylmethacrylate fine particles were not externally added. Physical properties of the obtained comparative non-magnetic toner (i) are shown in Table 1.

Production Example 6 of Nonmagnetic Toner A comparative nonmagnetic toner (ii) was obtained in the same manner as in Production Example 2 except that the true spherical polymethylmethacrylate fine particles were not added externally. Table 1 shows each physical property of the obtained comparative non-magnetic toner (ii).

Production Example 7 of Non-Magnetic Toner SF-1 was 163 before treatment with thermo-mechanical impact force.
Comparative non-magnetic toner (iii) was obtained in the same manner as in Production Example 1 except that the non-magnetic toner particles having SF-2 of 155 were used. The obtained comparative non-magnetic toner (ii
Table 1 shows the respective physical properties of i).

Production Example 8 of Non-Magnetic Toner SF-1 was 157 before treatment with thermo-mechanical impact force.
Comparative nonmagnetic toner (iv) was obtained in the same manner as in Production Example 2 except that nonmagnetic toner particles having SF-2 of 150 were used. Obtained comparative non-magnetic toner (iv)
Table 1 shows the respective physical property values of.

Production Example 9 of Nonmagnetic Toner Instead of the true spherical polymethylmethacrylate fine particles, styrene-methylmethacrylate copolymer fine particles having a surface area sphericity ψ of 0.80 (ψ = 0.8; primary number average particle diameter) 600 nm; BET specific surface area 12.5 m ² / g; glass transition temperature 98 ° C .; copolymerization weight ratio = 75: 25; weight average molecular weight 500,000) Comparative nonmagnetic in the same manner as in Production Example 1 Toner (v) was obtained. Physical properties of the obtained comparative magnetic toner (v) are shown in Table 1.

Production Example 10 of non-magnetic toner Polyester resin (weight average molecular weight 130,000; low molecular weight side peak 6000; glass transition point Tg 55 ° C.) 100 parts by weight Copper phthalocyanine (coloring agent) 7 parts by weight Dialkylsalicylic acid metal compound (negatively charged) Non-magnetic toner (E) was obtained in the same manner as in Production Example 1 except that the above materials were used. Physical properties of the obtained non-magnetic toner (E) are shown in Table 1.

Further, Table 2 shows the physical properties of the additives used in the above non-magnetic toners.

[0208]

[Table 1]

[0209]

[Table 2]

[0210]

[Table 3]

Photoreceptor Production Example 1 As a photoreceptor, an A1 cylinder having a diameter of 30 mm was used as a base. Layers having a structure as shown in FIG. 1 was produced.

(1) Conductive coating layer: A powder of tin oxide and titanium oxide dispersed in a phenol resin was used.
The film thickness was 15 μm.

(2) Undercoat layer: Modified nylon and copolymer nylon were used. The film thickness was 0.6 μm.

(3) Charge generation layer: A titanyl phthalocyanine pigment having absorption in a long wavelength region dispersed in butyral resin was used. The film thickness was 0.6 μm.

(4) Charge transport layer: A hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight of 20,000 by Oswald viscosity method) in a weight ratio of 8:10, and further polytetrafluoroethylene powder. (Particle size 0.
2 μm) was added to the total solid content in an amount of 5% by weight, and the mixture was uniformly dispersed. The film thickness was 20 μm. Photoconductor No. No. 1 had a contact angle with water of 93 degrees.

Pure water was used to measure the contact angle, and a contact angle meter CA-DS type manufactured by Kyowa Interface Science Co., Ltd. was used as the apparatus.

Photoreceptor Manufacturing Example 2 Photoreceptor No. In No. 2, up to the charge generation layer, it was produced in accordance with Photoreceptor Production Example 1. For the charge transport layer, a hole-transporting triphenylamine compound is added to a polycarbonate resin at 10:10.
What was melt | dissolved in the weight ratio of was used. The film thickness was 18 μm. On top of that, the same material is used as a protective layer 5: 1.
Polytetrafluoroethylene powder (particle size: 0.2 μm) was added to a solution dissolved in a weight ratio of 0 in an amount of 30% by weight based on the total solid content and uniformly dispersed. It was spray coated. The film thickness was 5 μm. The obtained photoconductor No. No. 2 had a contact angle with water of 101 degrees.

Photoreceptor Production Example 3 Up to the undercoat layer was produced in the same manner as in Photoreceptor Production Example 1.

(3) Charge generation layer: An azo pigment having absorption in the long wavelength region dispersed in butyral resin was used.
The film thickness was 0.6 μm.

(4) Charge transport layer: A hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight of 20,000 by Ostwald viscosity method) at a weight ratio of 8:10, and further polytetrafluoroethylene powder. 10% by weight of (particle size 0.2 μm) was added to the total solid content and uniformly dispersed. The film thickness was 22 μm. The obtained photoconductor No. 3 has a contact angle with water of 9
It was 6 degrees.

Photoreceptor Production Example 4 Photoreceptor No. 4 was obtained in the same manner as in Photoreceptor Production Example 3 except that the polytetrafluoroethylene powder was not added. 4 was produced. Photoconductor No. No. 4 had a contact angle with water of 74 degrees.

Photoreceptor Characteristics: The photoreceptor characteristics are measured under the process conditions of an actually used apparatus or conditions close thereto. As a measuring method, the surface electrometer probe is arranged immediately after the exposure position, and the photoconductor potential in the absence of exposure is V _d .

Then, the exposure intensity is gradually changed and the surface potential of the photosensitive member is recorded. The half-exposure intensity means the exposure intensity at the time when the photoconductor potential becomes half of the dark part potential, that is, V _d / 2. Furthermore, the potential when exposed with a light amount of 30 times the half exposure intensity is defined as the residual potential V _r .

The characteristics of the photoconductor production examples are evaluated. Laser beam printer as electrophotographic device (Canon: LB
P-860) was prepared. Process speed is 47m
m / s. The latent image formation was binary at 300 dpi. The photoconductor charger is replaced with a corona charger.

The photoconductor characteristics were measured by changing the laser light amount and monitoring its potential. At this time, in the laser exposure, the entire surface is exposed by continuous light emission in the sub-scanning direction.

Photoconductor No. In the measurement of 1, the dark area potential is −
700 V, the amount of light at which the dark part potential is halved, and the amount of half light at the photoconductor is 0.12 cJ / m ² , and the residual potential V _r is -55.
V, and the slope of the straight line connecting V _d and (V _d + V _r ) / 2 is 2900 Vm ² / cJ, so the slope of 1/20 is 1
It is 50 Vm ² / cJ. Photoreceptor characteristic curve and this 1 /
20 the inclination of the contact is 0.43cJ / m ^2, 5 times the half decay exposure is 0.60cJ / m ^2.

The same measurement was performed on the photoconductors Nos. 2-4. The results are shown in Table 3. As a graph of the photoconductor characteristics, the photoconductor No. No. 1 is shown in FIG.

[0228]

[Table 4]

Example 1 A laser beam printer (LBP-8Mark IV, manufactured by Canon Inc.) as an electrophotographic apparatus was modified as follows. The process speed was 47 mm / s.

The cleaning rubber blade in the process cartridge for the printer was removed. The charging system of the device was direct contact charging in which a rubber roller was brought into contact, and a direct current component (-1400 V) was used as an applied voltage.

Next, the developing portion of the process cartridge was modified. A medium resistance rubber roller (diameter 16 mm) made of urethane foam was used as a toner carrier instead of the stainless steel sleeve which was a toner supplier, and was in contact with the photosensitive drum. The rotational peripheral speed of the toner carrier is in the same direction at the contact portion with the photosensitive member, and is 1 with respect to the rotational peripheral speed of the photosensitive member.
It was driven so as to be 50%.

As a means for applying toner to the toner carrier, a coating roller to which a DC bias of -420V was applied was provided and brought into contact with the toner carrier. Further, a resin-coated stainless steel blade was attached for controlling the toner coating layer on the toner carrier. Figure 1
And as shown in FIG. The applied voltage applied to the toner carrier during development was DC component (-400V) only.

As for the charging potential of the photoconductor, the dark potential is -800V.
And the light portion potential was set to -150V as a standard.

In the modified machine, the roller charger was used to uniformly charge the photoreceptor. After charging, an electrostatic latent image is formed on the photoconductor by exposing the image portion with laser light,
After developing the electrostatic latent image with the non-magnetic toner A to form a toner image, the toner image is transferred to a transfer material by a transfer roller to which a bias voltage is applied, and the toner image on the transfer material is heated and pressurized by a roller fixing device. It became established in. The transfer roller is a transfer roller as shown in FIG. 4 [made of ethylene-propylene rubber in which conductive carbon is dispersed, volume resistance of conductive elastic layer 10 ⁸ Ω · cm, surface rubber hardness 24 °, diameter 20 mm,
The contact pressure 49 N / m (50 g / cm)] is constant with respect to the peripheral speed (48 mm / sec) of the photosensitive drum, +2000 V is applied as the transfer bias, and the non-magnetic toner (A) is used as the toner. Images were printed in an environment of a temperature of 23 ° C. and a humidity of 65% RH.

As the photoconductor, the photoconductor No. 1 of Production Example 2 was used. Two
(Contact angle with water: 101 degrees) was used. The exposure intensity at the time of forming a latent image on the photosensitive drum was changed in four steps as shown in Table 4. V _d and (V _d +
V _r ) / 2 is 0.25 cJ / m ² , which is less than the exposure intensity at the point where the straight line having a slope of 1/20 with respect to the slope of the line and the characteristic curve of the photoconductor, which is more than 5 times the half-exposure intensity 0 ．
85 cJ / m ² and ^two exposure intensities in between.
When the exposure intensity is 0.50 cJ / m ² , the light area potential is −15.
It became 0 V, which was used as the standard.

As shown in Table 4, images having excellent ghost, isolated dot reproducibility and gradation reproducibility were obtained.

At this time, the photosensitive drum No. The transfer efficiency from No. 2 to the transfer material was as high as 97%, and a good image without scattering of characters and lines in the transfer was obtained.

The evaluation method is described below.

Evaluation method: The following evaluations (1) to (3) are 1
It was carried out after the output of 00 images.

(1) For image evaluation related to a ghost caused by cleanerless, a black-and-white belt-shaped image for one round of the photosensitive drum is output, and then a halftone formed by a 1-dot horizontal line and a 2-dot blank is output. A pattern was used. A schematic diagram of the pattern is shown in FIG.

As the transfer material, 75 g / m ² plain paper,
A cardboard of 130 g / m ^{2 and} a cardboard of 200 g / m ^{2 and} a film for overhead projector (for OHP) were used.

The evaluation method was carried out by using a Macbeth reflection densitometer at the second round of the photosensitive drum in one print image, at the place where the black image was formed (black print portion) and the place where the black image was not formed (non-image portion). The difference between the measured reflection densities was calculated and calculated by the following formula.

Reflection density difference = reflection density (image formed place) -reflection density (image not formed) The smaller the reflection density difference, the better the evaluation level without ghost.

(2) Gradation was evaluated by measuring eight kinds of image densities with different pattern forming methods (see FIG. 10). Set the size of 1 dot to 42 μm (60
The evaluation was performed at 0 dpi).

From the viewpoint of tone reproducibility, the desirable density range of each pattern is preferably the following values, and evaluation was performed from this viewpoint.

[0246]   Pattern 1: 0.10 to 0.15 Pattern 2: 0.15 to 0.20   Pattern 3: 0.20 to 0.30 Pattern 4: 0.25 to 0.40   Pattern 5: 0.55-0.70 Pattern 6: 0.65-0.80   Pattern 7: 0.75 to 0.90 Pattern 8: 1.35

Regarding the criteria, those satisfying all of the above areas were judged as excellent; those with one deviation being normal; those with two or more deviations being bad.

(3) Regarding the reproducibility of isolated dots in a graphic image, the density of pattern 1 was used as a substitute. This is because the developing area is expanded and the density is increased as the latent image is blurred. Criteria of 0.10 to 0.15 are excellent; 0.
16 to 0.17 was considered as normal; 0.18 or more and less than 0.10.

(4) Durability of a large number of sheets was evaluated by visually confirming the presence or absence of image defects due to the fusion of the toner on the surface of the photosensitive drum after the printing of 5,000 sheets.

Excellent: Number of image defects is 3 or less Normal: Number of image defects is 4 to 10 Poor ... Number of image defects is 11 or more (5) Image density is 5 mm square solid black image using Macbeth densitometer And measured.

(6) Fogging is a reflection type densitometer (TOKY
O DENSHOKU CO. , LTD REFLE
CTOMETER ODEL TC-6DS) (Ds-D where Ds is the worst value of the reflectance of the white background after printing and Dr is the average value of the reflectance of the paper before printing)
The absolute value of r was taken as the fogging amount). A fogging amount of 2% or less is a good image with substantially no fogging, and a fogging amount of more than 5% is an unclear image with conspicuous fogging.

Example 2 An image output test was conducted in the same manner as in Example 1 except that the nonmagnetic toner (B) was used instead of the nonmagnetic toner (A). The results are shown in Table 4.

Example 3 An image output test was conducted in the same manner as in Example 1 except that the nonmagnetic toner (C) was used instead of the nonmagnetic toner (A). The results are shown in Table 4.

Example 4 An image output test was conducted in the same manner as in Example 1 except that the nonmagnetic toner (D) was used instead of the nonmagnetic toner (A). The results are shown in Table 4.

Example 5 An image output test was conducted in the same manner as in Example 1 except that the nonmagnetic toner (E) was used instead of the nonmagnetic toner (A). The results are shown in Table 4.

Comparative Examples 1 to 5 Image forming tests were conducted in the same manner as in Example 1 except that comparative specific magnetic toners (i) to (v) were used in place of the non-magnetic toner (A).

The results are shown in Table 4.

[0258]

[Table 5]

Examples 6 to 8 Image forming tests were conducted in the same manner as in Example 1 except that the photoconductors Nos 1, 3 and 4 were used. The fifth result
Shown in the table.

[0260]

[Table 6]

Magnetic Particle A As magnetic particle A for forming the magnetic brush charging roller, (Fe ₂ O ₃ ) _2.3 (Cu) having an average particle diameter of 25 μm is used.
Magnetic ferrite particles having a composition of _1.0 (ZnO) _1.0 were used. The magnetic particles A showed the applied electric field dependence of the graph A of FIG. 7. Table 6 shows the physical properties of the magnetic particles A.

[0262] to prepare a magnetic particle B was surface-treated magnetic particles B magnetic particles A 0.05 wt% of the surface of the titanium coupling agent (Ajinomoto Co., trade name KR TSS). The magnetic particles B showed the applied electric field dependence of the graph B of FIG. 7.

Table 6 shows the physical properties of the magnetic particles B.

[0264] was prepared magnetic particles C by oxidizing the surface of the magnetic particles C magnetic particles A. The magnetic particles C showed the applied electric field dependence of the graph C in FIG. 7.

Table 6 shows the physical properties of the magnetic particles C.

[0266] The magnetic particles D magnetic particles C100 parts surface, to prepare a magnetic particle D by coating with 10 percent by weight of carbon black dispersed silicone resin 1 parts by weight. Magnetic particles D are shown in FIG.
The graph D shows the dependency of applied voltage. Table 6 shows the physical properties of the magnetic particles D.

[0267] was prepared magnetic particles E with a surface of the magnetite particles of the magnetic particles E average particle size 50μm was oxidized. The magnetic particles E showed the applied voltage dependence of the graph E of FIG. 7.

[0268]

[Table 7]

Photoreceptor Manufacturing Example 5 Photoreceptor No. Reference numeral 5 is a photoreceptor (OPC) using an organic photoconductive substance for negative charging, which was prepared by providing five functional layers shown in FIG. 8 on an aluminum cylinder having a diameter of 30 mm.

The first layer is a conductive layer (conductive coating layer).
This is a conductive particle-dispersed resin layer having a thickness of about 20 μm, which is provided to smooth the defects of the aluminum cylinder and to prevent the generation of moire due to the reflection of laser exposure.

The second layer is a positive charge injection prevention layer (undercoat layer). The positive charge injected from the aluminum support prevents the negative charge charged on the surface of the photoconductor from being canceled. It is a medium resistance layer having a thickness of about 1 μm whose resistance is adjusted to about 10 ⁶ Ω · cm by a 6-66-610-12-nylon resin and methoxymethylated nylon.

The third layer is a charge generation layer. This is a layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin. Positive and negative charge pairs are generated by receiving the laser exposure.

The fourth layer is a charge transport layer. It is a layer having a thickness of 25 μm in which hydrazone is dispersed in polycarbonate resin and is a P-type semiconductor. Therefore, the negative charges charged on the surface of the photoconductor cannot move in this layer, and only the positive charges generated in the charge generation layer can be transported to the surface of the photoconductor.

The fifth layer is a charge injection layer. Ultra-fine SnO ₂ particles in photo-curable acrylic resin, and tetrafluoroethylene resin particles with a particle size of about 0.25 μm are dispersed in order to increase the contact time between the contact charging member and the photoconductor to achieve uniform charging. It was done. Specifically, 167 parts by weight of antimony-doped SnO ₂ particles having a resistance of about 0.03 μm and 100 parts by weight of resin, 20 parts by weight of tetrafluoroethylene resin particles, a dispersant Is dispersed in an amount of 1.2 parts by weight.

The coating solution thus prepared was applied by spray coating to a thickness of about 2.5 μm to form a charge injection layer.

Photoconductor No. The volume resistance value of the surface layer of No. 5 was 1 × 10 ¹⁵ Ω · cm in the case of the charge transport layer alone. The surface resistance of 1 is 5 × 10 ¹² Ω ・
fell to cm. Photoconductor No. The contact angle with water of 5 was 93 degrees.

Photoreceptor Manufacturing Example 6 Photoreceptor No. No. 6 is the photoconductor No. 6 up to the undercoat layer. It was created according to 5. For the charge generation layer, an oxytitanium phthalocyanine pigment having absorption in a long wavelength region dispersed in butyral resin was used. The film thickness was 0.7 μm. For the charge transport layer, a hole-transporting triphenylamine compound dissolved in a polycarbonate resin in a weight ratio of 10:10 was used. The film thickness was 18 μm. Further thereon, as a charge injection layer, 120 parts by weight of SnO ₂ particles (particle diameter 0.03 μm) having a low resistance in a composition obtained by dissolving the same material in a weight ratio of 5:10, relative to 100 parts by weight of the resin, Polytetrafluoroethylene resin particles (particle size 0.1 μm)
Was added to the total solid content in an amount of 30% by weight and uniformly dispersed, and the resultant was spray-coated on the charge transport layer. The film thickness was 3 μm. Photoconductor No. The surface resistance of 6 is 2
It was × 10 ¹³ Ω · cm, and the contact angle with water was 101 degrees.

Photoconductor Production Example 7 In the photoconductor production example 6, the charge injection layer (photoconductor surface layer).
Similarly, except that the polytetrafluoroethylene resin particles were not added to the photoconductor No. Created 7. Photoconductor No. 7
Had a contact angle with water of 78 degrees.

Physical properties of the photoconductors Nos. 5 to 7 are shown in Table 7.

[0280]

[Table 8]

Example 9 A laser beam printer (LBP-860 manufactured by Canon Inc., process speed 47 mm / se) as an electrophotographic apparatus
c) was prepared. The laser beam printer was modified so that the process speed was 1.5 times, and the process speed was 70 mm / s. Latent image formation is 600d
It was set to a binary value of pi.

The cleaning rubber blade of this process cartridge was removed.

Next, as the photoconductor, the photoconductor No. 5 was used. The contact charging member has magnetic particles B, an aluminum conductive sleeve having a non-magnetic surface blasted to make it stand as a magnetic brush, and a magnet roll contained therein. The sleeve for holding the particles and the photoconductor No. The gap with 5 is about 5
It was set to 00 μm. Approximately 5 m wide between the magnetic particles B and the photoconductor
m onto the sleeve to form a charging nip. The surface of the sleeve is 200% faster than the photoconductor No. 5
The photosensitive member N is rotated by rubbing in a direction opposite to the rotating direction of the photosensitive member N.
o. 5 and the magnetic brush were evenly contacted.

Here, the peripheral speed difference is calculated by the following formula.

V is the peripheral speed of the photosensitive member at the contact portion between the charging member and the photosensitive member, and v is the peripheral speed of the charging member.

Peripheral speed difference = (| Vv | / | V |) × 100

The magnetic flux density of the magnet roll is 0.1 T
And the photoconductor No. showing the maximum magnetic flux density. It was fixed at a position opposed to 5. The maximum magnetization of the magnetic particles A at 0.1 T was about 63 (Am ² / kg).

When the magnetic brush is fixed, the magnetic brush itself has no physical restoring force, and
Alternatively, when the magnetic brush is pushed away due to eccentricity or the like, it may be difficult to secure the nip of the magnetic brush, and charging failure may occur. For this reason, it is preferable to always contact the surface of a new magnetic brush, so in this embodiment, the magnetic brush is rotated in the opposite direction at twice the speed.

Further, the developing portion of the process cartridge was modified. Instead of the stainless steel sleeve, which is the toner supplier, a medium resistance rubber roller (diameter 16 mm) made of urethane foam was used as the toner carrier (developing roller), and the photosensitive member No. Abut on 5. The rotational peripheral speed of the toner carrying member was in the same direction at the contact portion with the photosensitive member, and was driven so as to be 180% of the rotational peripheral speed of the photosensitive member.

As a means for applying toner to the toner carrier, a coating roller to which a DC bias of -330V was applied was provided and brought into contact with the toner carrier. Further, a resin-coated stainless steel blade was attached for controlling the toner coating layer on the toner carrier. The applied voltage applied to the toner carrier during development is the DC component (-300V)
Only tried.

In the modified machine, a contact charging member was used and a DC bias of -700 V was applied to the photoreceptor No. 5 uniformly −6
It was charged to 80V. Subsequent to charging, the electrostatic latent image is formed on the photosensitive member No. by exposing the image portion with a laser beam. 5, the electrostatic latent image is developed on the non-magnetic toner (A) to form a toner image, the toner image is transferred to a transfer material by a transfer roller to which a bias voltage is applied, and then the toner image is fixed. .

A schematic diagram of this modified device is shown in FIG.

In the durability test, the exposure intensity of the photoconductor was
The durability test of 500 sheets was performed under the environment of 1.70 cJ / m ² and 23 ° C. and 55% relative humidity.

Image density, fog, ghost image evaluation, and character dropout evaluation were carried out at the initial stage and at the time of 100 sheets and 500 sheets.

Initially, the reproducibility of gradation was evaluated.

In the evaluation of "ghost" in Table 8, the maximum difference in reflection density in one transfer material is measured in the same manner as the evaluation of the ghost image. Initially, the maximum reflection density difference of 75 g / m ² plain paper, the maximum reflection density difference of 130 g / m ² thick paper, the maximum reflection density difference of 200 g / m ² thick paper, and the maximum reflection of OHP film Each density difference was measured, and the one having the largest reflection density difference among the four types of transfer materials was evaluated.

Evaluations were made on the 100th and 500th sheets in the same manner as in the initial stage. The evaluation was performed based on the following criteria.

[0298] Rank 0.00 if 0.00 In the case of 0.01 to 0.02, rank AA In case of 0.03 to 0.04 Rank A Rank B in the case of 0.05 to 0.07 In case of 0.08 ~ Rank C

In the evaluation of character voids, printing was performed for 3 dots, and evaluation was performed using a lattice pattern having a blank portion of 15 dots. As a transfer paper, postcard paper of 200 g / m ² was used.

If only the edge portion of the line remains on the entire surface of the image and the central portion of the line is blank, only the edge portion of the line remains at rank C and part of the image.
When the central portion of the line is white, the image is ranked B, and when the central portion of the line is not white, the image is ranked A.

The evaluation results are shown in Tables 8 and 9.

Examples 10 to 12 and Reference Example An image forming test was conducted in the same manner as in Example 9 except that nonmagnetic toners (B) to (E) were used instead of the nonmagnetic toner (A). Was done. The results are shown in Tables 8 and 9.

Comparative Examples 6 to 10 Image development tests were conducted in the same manner as in Example 9 except that comparative nonmagnetic toners (i) to (v) were used instead of the nonmagnetic toner (A). It was The results are shown in Tables 8 and 9
Shown in the table.

[0304]

[Table 9]

[0305]

[Table 10]

Examples 13 to 16 Example 9 is repeated except that magnetic particles A, C, D and E are used instead of the magnetic particles B to form a magnetic brush charging roller.
An image output test was conducted in the same manner as in. The results are shown in Tables 10 and 11. Example 16 using magnetic particles E
Was inferior to the other examples, so the test of 100 sheets or more was not performed.

Examples 17 and 18 Photoreceptor No. An image formation test was conducted in the same manner as in Example 9 except that the photoconductor Nos. 6 and 7 were used in place of 5. The results are shown in Tables 10 and 11.

Photoreceptor No. Since Example 18 using No. 7 was inferior to the other Examples, the test of 100 sheets or more was not performed.

[0309]

[Table 11]

[0310]

[Table 12]

[0311]

According to the present invention, the shape factor SF-1 to which the specific inorganic fine particles (a) and the true spherical fine particles (b) are externally added is 120 to 160, and SF-2 is 115 to 140.
By using the non-magnetic toner particles described above, the image forming method having no independent cleaning means can be favorably carried out.

Further, by using the image forming method of the present invention, dot dropout is prevented while preventing dropout in transfer, improving transfer efficiency, and maintaining high image density and latent image reproducibility in simultaneous cleaning during development. -High-quality, sharp images with excellent gradation reproducibility can be stably supplied to various transfer materials.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view for explaining a specific example of an image forming apparatus for carrying out an image forming method of the present invention.

FIG. 2 is an enlarged view of a developing device of the image forming apparatus shown in FIG.

FIG. 3 is a schematic cross-sectional view for explaining an example of a layer structure of a photoconductor that is an electrostatic latent image carrier.

4 is an enlarged view of a contact transfer member of the image forming apparatus shown in FIG.

FIG. 5 is a schematic explanatory view of another specific example of the image forming apparatus for carrying out the image forming method of the present invention.

FIG. 6 is a schematic explanatory view of an apparatus for measuring a dynamic resistance value of a contact charging member.

FIG. 7 is a graph showing a relationship between a resistance value of magnetic particles used for a contact charging member and an applied electric field.

8 is a schematic cross-sectional view for explaining an example of a layer structure of a photoconductor used in the image forming apparatus shown in FIG.

FIG. 9 is a diagram showing a ghost evaluation output pattern.

FIG. 10 is a diagram showing an output pattern for evaluating gradation reproducibility.

FIG. 11 is a schematic explanatory diagram of a measuring device for measuring the triboelectric charge amount of toner.

FIG. 12A is a diagram showing an example of a good image with no voids during transfer. FIG. 6B is a diagram showing an example of a defective image having a void in transfer.

FIG. 13 is a diagram showing the range of shape factors SF-1 and SF-2 of the non-magnetic toner particles used in the present invention.

FIG. 14 is a graph showing the relationship between the exposure intensity of the photoconductor and the potential of the photoconductor.

[Explanation of symbols]

100 photoconductor (electrostatic latent image carrier) 103 toner regulation blade 104 toner carrier (developing sleeve) 114 transfer roller 117 Contact charging means (charging roller) 117a Magnetic brush charging roller 127 Transfer material (transfer sheet) 128 heating roller 140 developer 141 toner application roller

Front page continuation (51) Int.Cl. ⁷ Identification code FI G03G 5/147 502 G03G 5/147 502 504 504 15/08 507 15/08 507L (72) Inventor Shigeo Urawa 3 Shimomaruko, Ota-ku, Tokyo No. 30-2 Canon Inc. (56) Reference JP 64-20587 (JP, A) JP 8-44190 (JP, A) JP 7-295388 (JP, A) JP 7-209952 (JP, A) JP-A-5-188637 (JP, A) JP-A-5-142849 (JP, A) JP-A-5-2287 (JP, A) JP-A-5-2284 (JP, A) A) JP-A-4-155361 (JP, A) JP-A-2-282267 (JP, A) JP-A-2-51168 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) G03G 9/08

Claims (33)

(57) [Claims] 1. A charging step of charging an electrostatic latent image carrier by a charging means, an exposure step of exposing the charged electrostatic latent image carrier to form an electrostatic latent image, and an electrostatic latent image developing means. Development process to develop a toner image on the electrostatic latent image bearing member by developing with a non-magnetic one-component toner possessed by, a transfer process to transfer the toner image to a transfer material with or without an intermediate transfer member, transfer after an image forming method having the step of recovering the developing unit toner remaining on the latent electrostatic image bearing member in the developing step, the non-magnetic toner particles of the non-magnetic one-component toner, the shape factor SF-1 120 to 160 and shape factor SF-2
Is 115 to 140, and the weight average particle diameter is 4 to 9 μm.
And the BET specific surface area measured using nitrogen gas is
A 1.4~2.1m ² / cm ^3, primary number average particle diameter 50nm or less of the inorganic fine particles (a)
And the primary number average particle size is 50 to 1000 nm,
True spherical fine particles (b) having a surface area shape sphericity ψ of 0.91 to 1.00 are externally added to the non-magnetic toner particles, and the non-magnetic one-component toner has a number average particle diameter of 3.5. ~ 8.
Is 0 .mu.m, the measured BET specific surface area using nitrogen gas and ^{Sb (m 2 / cm 3)} , the non-magnetic one-component toner <br/> over from the weight average particle diameter at the time of assuming sphericity When the calculated specific surface area per unit volume is St (m ² / cm ³ ), the following conditions 3.4 ≦ Sb ≦ 6.3 3.0 ≦ Sb / St ≦ 7.0 Sb ≧ St × 1. An image forming method characterized by satisfying 5 + 1.5. 2. The electrostatic latent image carrier is charged by contact charging means to which a bias voltage is applied, and the peripheral speed of the contact charging means is faster than the peripheral speed of the electrostatic latent image carrier. The image forming method described. 3. The image forming method according to claim 2, wherein the contact charging means is rotated in the counter direction and the rotation direction of the electrostatic latent image carrier. 4. The image forming method according to claim 2, wherein the peripheral speed of the contact charging means is 1.1 to 3 times the peripheral speed of the electrostatic latent image carrier. 5. The developing means has a toner carrying roller for carrying and carrying non-magnetic toner, and the non-magnetic toner layer on the toner carrying roller carries an electrostatic latent image at least at its closest portion. The image forming method according to claim 1, wherein the image forming method is in contact with the body surface. 6. The image forming method according to claim 5, wherein the toner carrying roller rotates at a peripheral speed of 1.1 to 3 times the peripheral speed of the electrostatic latent image carrier. 7. The developing means has an application roller for supplying a non-magnetic toner to the surface of the toner carrying roller and an application blade for forming a non-magnetic toner layer on the surface of the toner carrying roller. 7. The image forming method according to 5 or 6. 8. The image forming method according to claim 5, wherein the developing unit includes a coating roller to which a DC bias is applied and a toner carrying roller to which the DC bias is applied. . 9. The DC bias applied to the coating roller and the DC bias applied to the toner carrying roller have the same polarity, and the absolute value of the voltage of the DC bias applied to the coating roller is the toner carrying value. The image forming method according to claim 8, wherein the DC bias voltage applied to the roller is larger than the absolute value of the voltage. 10. The inorganic fine particles (a) have a primary number average particle diameter of 1 to 30 nm, and the true spherical particles (b) have a primary number average particle diameter of 70 to 900 nm. Image forming method. 11. The image forming method according to claim 1, wherein the true spherical particles (b) are true spherical resin particles. 12. The image forming method according to claim 11, wherein the true spherical resin fine particles are formed of a vinyl polymer or a vinyl copolymer. 13. The image forming method according to claim 11, wherein the spherical resin particles have a glass transition temperature of 80 to 150 ° C. 14. The inorganic fine particles (a) are externally added in an amount of 0.1 to 8 parts by weight per 100 parts by weight of the non-magnetic toner particles, and the true spherical particles (b) are 0.01 to 100 parts by weight per 100 parts by weight of the non-magnetic toner particles. 1.0 parts by weight of externally added.
The image forming method according to any one of 3 above. 15. The image forming method according to claim 1, wherein the true spherical particles (b) are spherical silica particles. 16. The image forming method according to claim 1, wherein the non-magnetic toner particles have a number average diameter of 3.5 to 8 μm. 17. The non-magnetic toner particles have a shape factor SF-
The value B from a second value obtained by subtracting the 100, according to one of claims 1 to 16 ratio B / A of the value A obtained by subtracting 100 from the value of shape factor SF-1 is 1.00 or less Image forming method. 18. The non-magnetic toner particles have a ratio B / A of 0.
The image forming method according to claim 17 , wherein the image forming ratio is 20 to 0.90. 19. The non-magnetic toner particles have a ratio B / A of 0.
The image forming method according to claim 17 , which is 35 to 0.85. 20. Inorganic fine particles (a) is located <br/> silica fine particles, spherical particles (b), the image formation according to any one of claims 1 to 19 is a spherical resin fine powder Method. 21. The image forming method according to claim 20 , wherein the inorganic fine particles (a) are hydrophobic silica fine particles. 22. The non-magnetic toner particles have a 60% pore radius of 3.5 nm or less in an integrated pore area ratio curve of pores of 1 nm to 100 nm of the toner particles. 22. The image forming method according to any one of 21 . 23. The electrostatic latent image carrier has a contact angle of 8 with water.
The image forming method according to any one of claims 1 to 22 and has a 5 degree or more surfaces. 24. An electrostatic latent image bearing member, an image forming method according to any one of claims 1 to 22 a contact angle with water has a surface of more than 90 degrees. 25. An electrostatic latent image bearing member The image forming method according to any one of claims 1 to 24 containing a substance having a fluorine atom on the surface layer. 26. The image forming method according to claim 25 , wherein the surface of the electrostatic latent image bearing member contains fluorine-containing resin particles. 27. The electrostatic latent image carrier is an OPC photosensitive member, and V _d and (V _d + of the photosensitive characteristic curve of the OPC photosensitive member are used.
V _r ) / 2 (where V _d is the dark portion potential and V _r is the residual potential) is in contact with a straight line having a slope of 1/20 with respect to the slope of the straight line connecting the photosensitive characteristic curve of the OPC photosensitive member. is the point of exposure intensity above, the image forming method according to any one of claims 1 to 26 to form an electrostatic latent image with less exposure intensity than 5 times the half-value exposure strength. 28. An electrostatic latent image bearing member, an image forming method according to any one of claims 1 to 27 having a charge injection layer on the surface. 29. An electrostatic latent image bearing member, an image forming method according to any one of claims 1乃<br/> optimum 28 bias voltage is charged by the magnetic brush is applied. 30. The electrostatic latent image carrier has a surface of 1 × 10 ⁸
The image forming method according to any one of claims 1 to 29 having a charge injection layer having a volume resistivity of ~10 ¹⁵ Ω · cm. 31. The image forming method according to any one of claims 1 to 30 an electrostatic latent image bearing member is an organic photoconductor using a phthalocyanine pigment. 32. The half-exposure amount of the electrostatic latent image carrier is 0.5.
^{cJ / m 2 (μJ / cm} 2) or less is claims 1 to 3
1. The image forming method according to any one of 1 . 33. A charging step of charging the electrostatic latent image carrier by a charging means, an exposure step of exposing the charged electrostatic latent image carrier to form an electrostatic latent image, and an electrostatic latent image developing means. Developing with a non-magnetic toner possessed by to form a toner image on the electrostatic latent image carrier, the toner image through an intermediate transfer member,
Or a non-magnetic one-component toner used in an image forming method having a transfer step of transferring to a transfer material without intervention, and a step of collecting the toner remaining on the electrostatic latent image bearing member after transfer to a developing means in the developing step. there, the non-magnetic toner particles of the non-magnetic one-component toner, the shape factor SF-1 is 120 to 160, a shape factor SF-2
Is 115 to 140, and the weight average particle diameter is 4 to 9 μm.
And the BET specific surface area measured using nitrogen gas is
A 1.4~2.1m ² / cm ^3, primary number average particle diameter 50nm or less of the inorganic fine particles (a)
And the primary number average particle size is 50 to 1000 nm,
True spherical fine particles (b) having a surface area sphericity ψ of 0.91 to 1.00 are externally added to the non-magnetic toner particles, and the non-magnetic one-component toner has a number average particle diameter of 3.5. ~ 8.
Is 0 .mu.m, the measured BET specific surface area using nitrogen gas and ^{Sb (m 2 / cm 3)} , the non-magnetic one-component toner <br/> over from the weight average particle diameter at the time of assuming sphericity When the calculated specific surface area per unit volume is St (m ² / cm ³ ), the following conditions 3.4 ≦ Sb ≦ 6.3 3.0 ≦ Sb / St ≦ 7.0 Sb ≧ St × 1. A non-magnetic toner characterized by satisfying 5 + 1.5.