JP3300865B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a system having a process of recovering a transfer residual toner on an image carrier and supplying it to a developing device in electrophotography, electrostatic recording, electrostatic printing, and the like. And an image forming method for visualizing a latent electrostatic image.

Further, the present invention relates to an image forming method including a step of collecting a transfer residual toner on an image carrier and supplying it to a developing device in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

[0003]

2. Description of the Related Art Conventionally, electrophotography has been disclosed in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910.
(US Pat. No. 3,666,363) and Japanese Patent Publication No. 43-24748 (US Pat. No. 4,707,71).
Many methods are known as described in US Pat. No. 361, No. 361, and the like. Generally, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means, and the latent image is formed. The image is developed using toner, then the toner image is transferred to a transfer material, and then fixed by heating, pressing, heating / pressing, or solvent vapor to obtain a copy.

Various methods and apparatuses have been developed in the above-described step of transferring the toner image to the transfer material, but there are still some toners that cannot be transferred onto the photosensitive member, that is, transfer residual toner. Exists. The transfer residual toner is cleaned by various methods and collected in the copying machine main body.

In recent years, there has been a demand for a small, high-speed copying machine capable of copying many sheets while maintaining high image quality. However, in the current high-speed copier,
Miniaturization is not necessarily achieved. One of the factors is the space after the transfer residual toner is collected. On the other hand, the treatment of the collected transfer residual toner is a very big problem with respect to the current environmental problems.
In other words, by supplying the collected transfer residual toner to the developing device, the above-mentioned problems can be overcome, and a small-sized, high-speed copying machine adapted to environmental problems can be achieved.

Until now, attempts have been made to supply the recovered transfer residual toner to a developing device and use it in a developing process. However, as this process is introduced and copying of a large number of sheets is repeated, for example, problems such as deterioration of fog occur, and it is difficult to provide a stable image for a long period of time.

In Japanese Patent Publication No. 63-40312 or Japanese Patent Publication No. 2-50467, a proposal for preventing fog by using a transfer paper containing a positively chargeable filler for a positively chargeable toner has been made. I have. However, the toner and the transfer paper are developed with a latent image on a latent image carrier to form a toner image, the formed toner image is transferred from the latent image carrier to a transfer material, and the latent image after the transfer is transferred. When the carrier is cleaned and the toner on the latent image carrier is collected, and the collected toner is supplied to a developing device and applied to a system used in a developing process, the image density is reduced as copying is continued. There is a problem that the image quality deteriorates and the image quality deteriorates.

[0008]

[0009]

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method which solves the above-mentioned problems and has a step of supplying a transfer residual toner on an image carrier to a developing device. is there.

Further, an object of the present invention is to supply a transfer residual toner on an image carrier to a developing device in order to obtain a high-quality image stably over a long period of time even under various environmental conditions. It is an object of the present invention to provide an image forming method having a step of performing the following.

Another object of the present invention is to provide an image forming method capable of performing good development with less toner consumption than in the case of using a conventional toner.

[0013]

[0014]

According to the present invention, a latent image on a latent image carrier is developed with toner on a toner carrier to form a toner image, and the formed toner image is formed on the latent image carrier. The latent image carrier after transfer is cleaned, the toner on the latent image carrier is collected, and the collected toner is supplied to a developing device to be used again in the developing process. In the method, the toner has negatively chargeable toner particles containing a binder resin, a colorant, a wax-like substance, and a negative charge control agent, and negatively chargeable silica fine powder is externally added to the negatively chargeable toner particles. The toner image is transferred onto a transfer paper having a weight average particle diameter of 4 to 11 μm and a calcium carbonate content of 3 to 35% by weight, and the latent image carrier after the transfer is transferred. When cleaning the latent image carrier, the negatively chargeable toner And the calcium carbonate from the transfer paper and the collected negatively-charged toner and calcium carbonate are transported by a transport pipe provided with a transport screw, and the transported negatively-charged toner and calcium carbonate are replenished with the negatively-chargeable toner. The present invention relates to an image forming method, wherein a toner and a toner are stirred and mixed, and then supplied onto a toner carrier and used in a developing process.

That is, by using a transfer paper having a calcium carbonate content of 3 to 35% by weight in a system for supplying the collected toner to a developing device and using it in a developing step, high image quality and high image density can be obtained. Can be supplied stably for a long time, and even in the case of high image density,
Good development can be performed with less toner consumption than conventional toners, which is advantageous in terms of economy and downsizing of a copying machine or printer body.

The reason why such an effect can be obtained by using the transfer paper for image formation of the present invention in a system in which a transfer residual toner is collected and supplied to a developing device to be used in a developing process is not necessarily required. Although it is not clear, it is estimated as follows.

In a system in which the transfer residual toner is collected, supplied to a developing device and used in a developing process, the transportability was first examined. As the transporting device, a simple transporting device is preferable from the viewpoint of space and cost in the copying machine. For example, there is a transport pipe provided with a transport screw.
The transportability of such a simple transport device greatly depends on the fluidity of the collected toner, and an appropriate fluidity of the recovered toner is necessary for performing favorable transport.

As a specific method of examining the transportability, the toner on the latent image carrier is directly collected by a cleaner without being transferred (in this case, no transfer paper is used), and is transferred to a developing device through a transport path. And a series of continuous tests in which the toner on the latent image carrier was periodically transferred to a transfer paper to check the image density and image quality. Initially, the image quality was high and the image density was high, but as the continuous test was performed, the image density gradually decreased. Further, there is a case where the toner is clogged in the transport path for supplying the collected toner to the developing device and scattered outside the transport path. Further, when the toner packed in the transport path is rapidly supplied during the developing process, the uniform mixing with the undeveloped toner is reduced, and a charging failure on the sleeve may occur. After various studies on these causes, the following became clear. When the toner on the latent image carrier was directly collected by the cleaner without being transferred, the excessively high flowability of the collected toner reduced the toner transportability in the transport path, and consequently caused toner clogging. It has become apparent that this may cause the problems described above. Further, regarding the decrease in image density, the toner developed on the latent image carrier and collected by the cleaner without being transferred during the process,
This is probably due to mechanical or thermal damage.

Therefore, as a result of intensive studies by the present inventors, the latent image on the latent image carrier is developed to form a toner image,
The formed toner image is transferred from the latent image carrier, the latent image carrier after the transfer is cleaned, the toner on the latent image carrier is collected, and the collected toner is supplied to a developing device to be used in a developing process. System with a calcium carbonate content of 3
It has become apparent that all of the above-mentioned problems can be solved by using the transfer paper for image formation of about 35% by weight. That is, in the above-described system, it is possible to control the fluidity of the collected toner by collecting not only the toner on the latent image carrier but also the calcium carbonate contained in the transfer paper for image formation of the present invention. Thus, the transportability of the toner in the transport path is improved. In addition, calcium carbonate was negatively charged when mixed with a positively chargeable toner, and positively charged when mixed with a negatively chargeable toner. This is considered to have a function of improving the developing property of the collected toner in order to make the polarity of the negatively charged toner more negative and the polarity of the positively charged toner more positive during development. . Therefore, it is possible to control the deterioration of the developing property of the recovered toner that has been mechanically or thermally damaged by the developing property improving effect of calcium carbonate, and to obtain a copy having high image quality and high image density for a long time.

The configuration of the present invention will be described in more detail.

As the transfer paper applied to the present invention, it is preferable to use an image forming transfer paper having a calcium carbonate content of 3 to 35% by weight, preferably 5 to 30% by weight. If the calcium carbonate content exceeds 35% by weight, the calcium carbonate and the toner, which are opposite to each other in charge, tend to form aggregates and cause fogging. On the other hand, when the calcium carbonate content is less than 3% by weight, it does not work to maintain the developability during durability. Alternatively, problems arise such as lowering of transportability, causing scattering of toner and poor charging. Further, the actual amount of calcium carbonate in the recovered toner is determined by using the image forming transfer paper of the present invention.
It is controlled to 0.3 to 20% by weight, which is preferable. Further, the ratio of the calcium carbonate content X% in the transfer paper for image formation to the calcium carbonate content Y% in the recovered toner is preferably in the range of 0.05 ≦ Y / X ≦ 0.8.

The toner applicable to the present invention includes:
Either a one-component toner or a two-component toner can be preferably used. However, the effect of improving the developing property of calcium carbonate on the recovered toner having a reduced developing property due to mechanical or thermal damage is one component without carrier. Toner is more pronounced and preferred. In consideration of image quality and the like, the toner particle size is 4 to 11 μm in weight average particle size.
Is more preferred.

The method for cleaning the transfer residual toner on the latent image carrier according to the present invention may be any method such as blade cleaning, web cleaning, fur brush cleaning, magnetic brush cleaning, and a cleaning method using a combination thereof. Although preferred, blade cleaning with an elastic blade is more preferably used. The developing method of directly supplying the toner collected after cleaning to the developing device includes a method of directly supplying the toner to the developing device and a method of first supplying the toner to a container containing the replenishing toner and then supplying the toner together with the replenishing toner to the developing device. In the present invention, any method can be preferably used.

As a method of supplying the toner collected after cleaning to the developing device, a method of directly supplying the toner to the developing device or a method of first supplying the toner to a container containing the toner for replenishment, and then supplying the toner together with the toner for replenishment to the developing device. Although a method is mentioned, in this invention, it can use preferably in any case.

For reference, a method for measuring the charge amount of calcium carbonate is described below.

0.2 g of calcium carbonate and 9.8 g of a positively chargeable toner and 9.8 g of a negatively chargeable toner each having a main particle size of 200 to 300 mesh which were left overnight in an environment of 23.5 ° C. and 60% RH. Weigh precisely in the above environment, about 5
Mix thoroughly (hold in hand and shake up and down approximately 125 times for about 50 seconds) in a polyethylene jar with a lid having a volume of 0 cc.

Next, as shown in FIG. 3, about 2.0 g of the mixture is placed in a metal measuring container 32 having a 400-mesh screen 33 at the bottom, and a metal lid 34 is placed. At this time, the weight of the entire measurement container 32 is weighed and defined as W ₁ (g). next,
In the suction device 31 (the part in contact with the measurement container 32 is at least an insulator), the air is sucked from the suction port 37 and the air volume control valve 36
Is adjusted to bring the pressure of the vacuum gauge 35 to 250 mmHg.
In this state, sufficient suction is performed for 5 minutes to remove calcium carbonate by suction. At this time, the potential of the electrometer 39 is set to V (volt).
And Here, 38 is a capacitor whose capacity is C (μ
F). Further, the weight of the whole measurement container after suction is weighed to be W ₂ (g). The charge amount of this calcium carbonate (μc
/ G) is calculated as follows.

Charge amount = CV / (W ₁ -W ₂ ) When the toner used in the present invention is, for example, a one-component magnetic toner, the following components can be used.

In the case of using a pressure and heat roller fixing device having an oil application device, any known binder material for toner can be used as the binder.
Styrenes such as polystyrene, poly-p-chlorostyrene, and polyvinyl toluene, and their substituted polymers; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene -Acrylate copolymer, styrene-methacrylate copolymer, styrene α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer Styrene-based copolymers such as polymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers; polyvinyl chloride, phenolic resins, natural Resin-modified phenol 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, cumarone indene resin, Petroleum-based resins can be used.

In the heat and pressure roller fixing method in which almost no oil is applied, the so-called offset phenomenon in which a part of the toner image on the toner image support member is transferred to the roller and the adhesion of the toner to the toner image support member are important. It is a problem. These problems must be taken into account at the same time, because toners that fix with less heat energy tend to block or cake during storage or in a developer. The physical properties of the binder in the toner are most important in these phenomena. However, according to the study of the present inventors, when the content of the magnetic substance in the toner is reduced, the toner is fixed at the time of fixing as described above. Although the adhesion of the toner to the image supporting member is improved, offset tends to occur, and blocking or caking tends to occur. Therefore,
In the present invention, when using a heat and pressure roller fixing method in which almost no oil is applied, selection of a binder substance is more important. Preferred binders include crosslinked styrenic copolymers or polyesters. Examples of the comonomer of the styrene-based copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, Methyl methacrylate, ethyl methacrylate,
Monocarboxylic acid having a double bond such as butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substitute thereof; for example, maleic acid, butyl maleate, methyl maleate, dimethyl maleate, etc. Dicarboxylic acids having the same double bond and substituted products thereof; for example, vinyl chloride,
Vinyl esters such as vinyl acetate and vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene; and vinyl methyl ketone;
Vinyl ketones such as vinyl hexyl ketone; vinyl monomers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether and the like are used alone or in combination of two or more. Here, as the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene, for example, ethylene glycol diacrylate and ethylene glycol diacrylate Divinyl compounds such as methacrylate, 1,3-butanediol dimethacrylate and the like having two double bonds, divinylaniline, divinylether, divinylsulfide, divinylsulfone and the like, and compounds having three or more vinyl groups Are used alone or as a mixture.

In the case of using the pressure fixing method, a known binder resin for pressure fixing toner can be used.
For example, polyethylene, polypropylene, polymethylene,
Examples include polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, and paraffin.

Examples of the magnetic material contained in the magnetic toner include iron oxides such as magnetite, γ-iron oxide, ferrite, and iron-rich ferrite; metals such as iron, cobalt, and nickel; Copper, lead, magnesium, tin, zinc, antimony,
Alloys with metals such as beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium and mixtures thereof.

These ferromagnetic materials have an average particle size of 0.1 to 1
μm, preferably about 0.1 to 0.5 μm. The amount contained in the magnetic toner is 60 to 120 parts by weight, preferably 6 to 120 parts by weight, per 100 parts by weight of the resin component.
5 to 110 parts by weight.

The magnetic characteristics when 10K Oersted is applied are as follows: the coercive force is 20 to 150 Oersted saturation magnetization;
Desirable is 200 emu / g and residual magnetization of 2 to 20 emu / g.

In the magnetic toner, a charge control agent may be blended (internally added) to the toner particles or mixed (externally added) with the toner particles.

When a charge control agent is added to the magnetic toner,
Examples of the negative charge control agent used include, for example, an organometallic complex,
Chelate compounds are effective and include monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based 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.

Examples of the positive charge control agent to be added to the magnetic toner include nigrosine and its modified products, quaternary ammonium such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate. Salts, diorganotin oxides such as dibutyltin oxide, dioctyltin oxide and dicyclohexyltin oxide, and diorganotin borates such as dibutyltin borate, dioctyltin borate and dicyclohexyltin borate can be used.

In addition, the general formula

[0039]

Embedded image Or a copolymer with a polymerizable monomer such as styrene, acrylic acid ester, and methacrylic acid ester as described above can be used as a positive charge control agent. Also has the function as.

The above-mentioned charge control agent (having no action as a binder resin) is preferably used in the form of fine particles. In this case, the number average particle size of the charge control agent is
Specifically, it is preferably 4 μm or less (more preferably 3 μm or less).

When internally added to the toner, such a charge control agent is preferably used in an amount of 0.1 to 20 parts by weight (more preferably 0.2 to 10 parts by weight) based on 100 parts by weight of the binder resin.

Various additives may be added to the magnetic toner, if necessary, internally or externally. As the coloring agent, conventionally known dyes and pigments can be used,
Usually, 0.5 to 20 parts by weight may be used for 100 parts by weight of the binder resin.

As other additives, for example, lubricants such as Teflon, zinc stearate and polyvinylidene fluoride are preferable, and polyvinylidene fluoride is particularly preferable. Or cerium oxide, silicon carbide, abrasives such as strontium titanate,
Among them, strontium titanate is preferable. Or, for example, a fluidity imparting agent such as titanium oxide and aluminum oxide,
Among them, a hydrophobic substance is particularly preferable. A small amount of an anti-caking agent or a conductivity-imparting agent such as carbon black, zinc oxide, antimony oxide, or tin oxide, or white and black fine particles of opposite polarity can also be used as a developability improver.

For the purpose of improving the releasability at the time of fixing with a hot roll, a wax-like substance such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, microcrystalline wax, carnauba wax, sasol wax, paraffin wax is added to 100 parts by weight of a binder resin. 0.5 ~
Adding to about 10 parts by weight of toner is also a preferred embodiment of the present invention.

The magnetic toner may be internally or externally mixed with silica fine powder, but is more preferably externally mixed. When magnetic toner particles are brought into contact with the surface of a cylindrical conductive sleeve having a magnetic field generating means inside due to triboelectric charging, the number of times of contact between the toner particle surface and the sleeve increases, causing wear of the toner particles. Easier to do. When the magnetic toner according to the present invention is combined with silica fine powder, wear is significantly reduced because the silica fine powder is interposed between the toner particles and the sleeve surface. As a result, the life of the magnetic toner can be extended, and a developer having the magnetic toner that is more excellent for long-term use can be obtained.

To prepare a magnetic toner, a magnetic powder, a thermoplastic resin, a fixing aid, a pigment or dye as a colorant, if necessary, a charge control agent, and other additives are sufficiently mixed by a mixer such as a ball mill. Then, using a hot kneader such as a heating roll, a kneader, or an extruder, the pigments or dyes were dispersed or dissolved while the resins were mutually mixed and melted and kneaded, and then cooled and solidified, followed by pulverization and classification. Thereafter, if necessary, the silica fine powder, the friction reducing substance and the like are externally added and mixed using a dry mixer such as a Henschel mixer or Papen-Meier to obtain a magnetic toner.

In the present invention, an apparatus in which the developing step is carried out with a one-component magnetic toner is specifically shown in FIG. 2 and will be described in detail, but this does not limit the present invention at all.

In FIG. 2, reference numeral 1 denotes a latent image carrier (so-called photosensitive member) such as a rotating drum type in a transfer type electrophotographic method, an insulator such as a rotating drum type in a transfer type electrostatic recording method, and an electrofax method. A latent image carrier such as a photosensitive paper or an electrostatic recording paper in a direct type electrostatic recording method, on which an electrostatic latent image is formed by a latent image forming process device or the same process mechanism (not shown), I'm moving.

Reference numeral 2 denotes an overall developing device, 21 denotes a hopper containing toner, 22 denotes a rotating cylindrical body (hereinafter referred to as a sleeve) as a toner carrier (developer layer supporting member), and a magnetic roller or the like inside. The generating means 23 is built in.

The sleeve 22 has a substantially right half circumferential surface exposed in the hopper 21 and a substantially left half circumferential surface exposed outside the hopper, and is supported by a bearing. A doctor blade 27 serving as a toner application member disposed with the lower side edge portion approached is a stirring member for toner in the hopper.

The axis of the sleeve 22 is substantially parallel to the generatrix of the latent image carrier 1 and is closely opposed to the surface of the latent image carrier 1 with a small gap α.

The surface moving speeds (peripheral speeds) of the latent image carrier 1 and the sleeve 22 are substantially the same, or the peripheral speed of the sleeve 22 is slightly higher. Also the alternating bias voltage applying means S ₀ is between the latent image bearing member 1 and the sleeve 22 DC bias voltage applying means S
_{Due to 1} , a DC voltage and an AC voltage are superimposed and applied.

The substantially right half peripheral surface of the sleeve 22 is
The toner near the sleeve surface is always in contact with the toner reservoir inside the sleeve, and the toner is generated on the sleeve surface.
As a magnetic adhesion layer by the magnetic force and by electrostatic force. When the sleeve 22 is rotated, the deposited toner layer on the sleeve surface is advice service as a thin layer toner layer T ₁ of the respective portions substantially uniform thickness in the process of passing through the doctor blade 24 position. The toner is charged mainly by frictional contact between the sleeve surface accompanying the rotation of the sleeve 22 and the toner in the toner reservoir near the sleeve, and the toner thin layer surface of the sleeve 22 is brought into contact with the surface of the latent image carrier 1 as the sleeve rotates. , And passes through the developing area A, which is the closest part between the latent image carrier 1 and the sleeve 22. In the course of this passage, the sleeve 22
The toner of the thin toner layer on the surface side flies due to the DC and AC electric fields generated by the DC and AC voltages applied between the latent image carrier 1 and the sleeve 22, and the surface of the latent image carrier 1 in the development area A and the sleeve 22. Reciprocate between surfaces. Eventually, the toner on the sleeve 22 side selectively moves and adheres to the surface of the latent image carrier 1 according to the potential pattern of the latent image, and the toner image T ₂
Are sequentially formed.

The sleeve surface on which the toner has been selectively consumed after passing through the developing area A is re-supplied by re-rotating the toner into the toner reservoir of the hopper 21, and the sleeve 22 is always supplied to the developing area A. thin toner layer T ₁ side is rotated, the repetitive copying process is performed.

[0055]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which do not limit the present invention in any way. All parts in the following formulations are parts by weight.

Example 1 Styrene / butyl acrylate / butyl maleate / divinylbenzene copolymer: 100 parts (copolymerization weight ratio: 73.5 / 19/7 / 0.5) Iron trioxide (average particle size) Diameter: 0.2 μm): 85 parts ・ Chromium complex of 3,5-ditert-butylic acid: 2 parts (Number average particle size: 2.8 μm) ・ Low molecular weight polypropylene: 3 parts After the above materials are mixed well by a blender And a twin screw extruder set at 110 ° C. The obtained kneaded material is cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized powder is subjected to a multi-divided classifier utilizing the Coanda effect. Then, the ultrafine powder and the coarse powder were strictly classified and removed at the same time to obtain a black fine powder having a weight average particle size of 9.5 μm.

100 parts of the obtained black fine powder was coated with negatively charged hydrophobic dry silica (BET specific surface area: 240 m ² / g).
0.5 part was added and mixed with a Henschel mixer to obtain a negatively chargeable insulating magnetic toner.

As shown in FIG. 1, the latent image carrier after the transfer is cleaned to collect the toner on the latent image carrier, and the toner is replenished by passing the toner through a pipe provided with a conveying screw therein. The magnetic toner was supplied to a hopper, further lightly stirred with a replenishing toner in the hopper, and then supplied to a developing device and charged into a Canon copier NP6060 modified so as to be used in a developing process. Further, an original having a printing ratio of 6% was transferred to an A4 size copying paper having a calcium carbonate content of 15% for A4 size copying paper, and an image output test was continuously performed on 250,000 sheets. When the amount of calcium carbonate in the recovered toner at the time of 20,000 sheets of the image formation test was measured, it was 3.5%. Table 1 shows the results of the 250,000-sheet image output test.

At the initial stage and after the endurance test of 250,000 sheets,
The image density was very high, and an image with excellent fog was obtained. The toner consumption at this time was 0.047 g / sheet, which was very small.

Example 2 Evaluation was performed in the same manner as in Example 1 except that a transfer paper having a calcium carbonate content of 31% by weight was used.

As shown in Table 1, initially, the image density,
All aspects of fog were equivalent to Example 1. However, in the image after 250,000 sheets, fog occurred slightly,
It was not at a level that would cause a problem in practical use. Other characteristics were the same as in Example 1.

Example 3 Evaluation was performed in the same manner as in Example 1 except that a transfer paper having a calcium carbonate content of 4% by weight was used.

As shown in Table 1, initially, the image density,
In all respects of fog and toner scattering, the results were the same as in Example 1. However, in the image after 250,000 sheets, the image density was slightly low at 1.32, but not at a level that would pose a practical problem. Also, some toner scattering occurred in the copying machine. About fog, it was equivalent to Example 1.

Comparative Example 1 Evaluation was performed in the same manner as in Example 1 except that neutral paper containing 38% by weight of calcium carbonate was used as the transfer paper. Table 1 shows the results. Initially, the same image characteristics as those of the first embodiment were shown. However, after 250,000 copies, fog was considerably deteriorated. Other image characteristics were the same as in Example 1.

Comparative Example 2 Evaluation was made in the same manner as in Example 1 except that transfer paper having a calcium carbonate content of 1.7% by weight was used. Table 1 shows the results. Initially, the same image characteristics as those of the first embodiment were shown. However, after 250,000 sheets, the image density was a low value of 1.17.
Further, a large amount of toner scattered in the copying machine. About fog, it was equivalent to Example 1.

Example 4 Styrene / butyl acrylate copolymer: 70 parts (copolymerization weight ratio 82/18, maximum value in molecular weight distribution: 13,000, Mw / Mn: 2.5) Butyl acrylate copolymer: 30 parts (copolymerization weight ratio 80/20, Mw: 93,900, Mn: 112,000) Iron trioxide (average particle size: 0.2 μm): 80 parts 7. Nigrosine: 2 parts-Low molecular weight polypropylene: 3 parts In place of the toner used in Example 1, the above materials were used, and kneading, pulverization, and classification were performed in the same manner as in Example 1.
A black fine powder of 95 μm was obtained.

To 100 parts of the obtained black fine powder, positively charged hydrophobic dry silica (BET specific surface area: 200 m ² / g)
0.6 part was added and mixed with a Henschel mixer to obtain a positively chargeable insulating magnetic toner. The latent image carrier after the transfer is cleaned to collect the toner on the latent image carrier, and the toner is supplied to a toner hopper for replenishment by passing the toner through a pipe provided with a conveying screw therein. After lightly stirring with the replenishing toner, the magnetic toner was supplied to a Canon copier NP4050 modified so as to be supplied to a developing device and used in a developing process.
100,000 sheets were durable and evaluated in the same manner as described above.

As shown in Table 1, in the initial and 100,000-sheet durability tests, an excellent image having an extremely high image density and no fog was obtained. Further, no toner scattering occurred in the copying machine. Further, the toner consumption amount at this time is 0.1.
051 g / sheet, which was very small.

Example 5 Evaluation was performed in the same manner as in Example 4 except that a transfer paper having a calcium carbonate content of 31% by weight was used.

As shown in Table 1, initially, the image density,
All aspects of fog were equivalent to Example 1. However, in the image after 100,000 sheets, fog occurred slightly,
It was not at a level that would cause a problem in practical use. Other characteristics were the same as in Example 4.

Example 6 Evaluation was performed in the same manner as in Example 4 except that a transfer paper having a calcium carbonate content of 4% by weight was used.

As shown in Table 1, initially, the image density,
In all respects of fog and toner scattering, it was equivalent to Example 4. However, in the image after 100,000 sheets, the image density was slightly low at 1.29, but not at a level that would pose a practical problem. Also, some toner scattering occurred in the copying machine. The fog was the same as in Example 4.

Comparative Example 3 Evaluation was performed in the same manner as in Example 4 except that neutral paper containing 38% by weight of calcium carbonate was used as the transfer paper. Table 1 shows the results. Initially, the same image characteristics as those of the fourth embodiment were shown. However, after 100,000 sheets, fog had considerably deteriorated. Other image characteristics were the same as in Example 4.

Comparative Example 4 Evaluation was performed in the same manner as in Example 4 except that a transfer paper having a calcium carbonate content of 1.7% by weight was used. Table 1 shows the results. Initially, the same image characteristics as those of the fourth embodiment were shown. However, after 100,000 sheets, the image density was a low value of 1.15.
Further, a large amount of toner scattered in the copying machine. The fog was the same as in Example 4.

Comparative Example 5 The toner used in Example 1 was used to clean the transferred latent image carrier and collect the toner on the latent image carrier. The collected toner was supplied to the developing device. The evaluation was performed in the same manner as in Example 1 except that an image was formed with a normal Canon copier NP6060 not used in the developing process.

In the image characteristics, the same result as in Example 1 was obtained.
The amount was 57 g / sheet, and it was clear that the toner consumption was larger than that in Example 1. This suggests that the present invention is effective in cleaning the latent image carrier after transfer, collecting the toner on the latent image carrier, supplying the collected toner to a developing device, and using the toner in a developing process. You.

[0077]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a developing device modified to supply a collected transfer residual toner to a developing device.

FIG. 2 is a specific cross-sectional view of a developing device used in a developing process.

FIG. 3 is an explanatory diagram of a charge amount measuring device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 latent image carrier 2 whole developing device 11 toner supply hopper 12 developing device 13 pre-transfer charger 14 transfer charger 15 separation charger 16 cleaner 17 primary charger 18 waste toner delivery pipe provided with transport screw 19 latent Image carrier 21 Hopper 22 Toner carrier (sleeve) 23 Magnetic roller 24 Doctor blade 27 Toner stirring member in hopper T Toner in hopper T ₁ Toner on sleeve T ₂ Toner on latent image carrier S ₀ Alternating bias voltage applying means S ₁ DC bias voltage applying means A Developing area α Gap between latent image carrier and sleeve 31 Aspirator 32 Measuring container 33 Screen 34 Lid 35 Vacuum gauge 36 Air flow control valve 37 Suction port 38 Condenser 39 Electrometer

Continuation of the front page (56) References JP-A-59-162560 (JP, A) JP-A-3-141367 (JP, A) JP-A-4-91292 (JP, A) JP-A-4-147152 (JP, A) JP-A-57-19774 (JP, A) JP-A-7-64316 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 7/00 G03G 9/08 375 G03G 21/10

Claims (7)

(57) [Claims] 1. A latent image on a latent image carrier is transferred to a toner carrier on a latent image carrier.
And developed with toner to form a toner image, the formed toner image is transferred onto the transfer material from the image bearing member, to clean the latent image bearing member after the transfer, the toner on the latent image bearing member In an image forming method in which the collected toner is supplied to a developing device and used again in the developing step, the toner contains a binder resin, a colorant, a wax-like substance, and a negative charge control agent. It has a negatively charged toner particles, negative zone
Negatively charged silica fine powder is externally added to the conductive toner particles.
Negatively chargeable toner having a weight average particle size of 4
A ～11Myuemu, calcium carbonate content transferring the toner image on the transfer paper 3 to 35 wt%, when cleaning the latent image bearing member after the transfer, negatively chargeable toner and on the latent image bearing member Collect calcium carbonate from transfer paper and transport the collected negatively charged toner and calcium carbonate
Transported by a transport pipe provided with Liu, a negatively chargeable toner and calcium carbonate that has been conveyed, replenishing
On the toner carrier after stirring and mixing with the negatively chargeable toner
And an image forming method for supplying the toner to a developing process. 2. A method according to claim 1, calcium carbonate content of the recovered toner is characterized in that 0.3 to 20 wt%
2. The image forming method according to 1., 3. Content of calcium carbonate (X) in transfer paper
When image forming method according to claim 1 or 2 ratio of the calcium carbonate content in the collected toner (Y) is characterized by satisfying the following relation 0.05 ≦ Y / X ≦ 0.8. 4. The charge control agent has a number average particle size of 4 μm.
The image forming method according to any one of claims 1 to 3, wherein the or less. 5. The transfer paper according to claim 5, wherein the calcium carbonate is 5 to 3 times.
The image forming method according to any one of claims 1 to 4 , wherein the content is 0% by weight. 6. The cleaning of the latent image carrier after the transfer includes blade cleaning, web cleaning,
The image forming method according to any one of claims 1 to 5 , wherein the toner and calcium carbonate on the latent image carrier are collected by performing fur brush cleaning, magnetic brush cleaning, or a combination thereof. 7. colorant, an image forming method according to any one of claims 1 to 6, characterized in that a magnetic material.