JP3333976B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for developing an electrostatic latent image with toner to form an image, and more particularly to an image forming method employing a toner recycling system.

[0002]

2. Description of the Related Art In an electrophotographic method, for example, an electrostatic latent image carrier formed of a photoconductive photoreceptor is usually charged and exposed to form an electrostatic latent image. The toner image is developed with fine particles containing a colorant or the like, and the obtained toner image is transferred to a support such as transfer paper and fixed to form a visible image. On the other hand, the photoreceptor after the transfer is neutralized, and then the toner remaining on the photoreceptor without being transferred is cleaned and used for the next image formation. In order to obtain a visible image as described above, it is necessary to fix a toner image. Conventionally, a heat roll fixing method which has high thermal efficiency and can perform high-speed fixing has been widely used.

On the other hand, from the viewpoint of economical use of toner, a so-called toner recycling system is adopted in which toner collected by cleaning (hereinafter referred to as "recycled toner") is returned to a developing device and reused. Image forming methods have attracted attention. The following characteristics are required for the toner applied to this recycling system.

[0004] The toner is not deformed or crushed by a shearing force applied in a cleaning process and a toner conveying process (recycling process) to a developing device.

[0005] A change in the surface condition of the toner is small.

In order to respond to such a demand, for example, (1) Japanese Patent Application Laid-Open No. 2-110572 discloses an image forming method employing a toner recycling system in which a metal-crosslinked styrene-acryl copolymer resin, a polyolefin, Fatty acid amide or fatty acid ester, containing hydrophobic inorganic fine particles, polyolefin 5 parts by weight or more, fatty acid amide
Ratio A of ester content A and polyolefin content B
A method using a developer having / B of 1 or more has been proposed.

Various methods have been proposed for mixing the external additives. For example, (2) Japanese Patent Application Laid-Open No. 2-57027 discloses a method of forming a rotating piece and a fixed piece under the conditions of an ambient temperature of 10 to 90 ° C. A method has been proposed in which a colored particle and an additive are mixed by passing through an impact section having a shortest gap of 0.5 to 30 mm and an impact section having a shortest gap of 0.5 to 30 mm formed from two types of rotating pieces. (3) Japanese Patent Application Laid-Open No. 4-328579 proposes a production method in which toner particles and a surface treating agent are mixed at a toner temperature of 40 ° C. or less and a shear peripheral speed of a mixer of 20 m / sec or more.

[0008] On the other hand, it is known to use a fluororesin as a carrier coating material as a carrier particle, and it has been proposed to use a magnetic material-dispersed carrier in which the abundance of specific atoms on the carrier surface is defined. For example, (4) Japanese Patent Publication No. 2-17109 discloses a molecular weight / intrinsic viscosity of 0.01 to less than 50 wt% of a monomer mixture containing a monomer of the general formula (trifluoromethyl methacrylate) on a carrier core material surface. Carriers have been proposed that coat the 2.0 polymer or compositions containing the polymer.

(5) Japanese Patent Application Laid-Open No. 3-1164 discloses that the abundance of fluorine atoms in all atoms on the carrier surface is 6 to 30 atomic.
There has been proposed a method using a carrier with a percentage of%.

[0010]

However, in the technique described in the above-mentioned publication (1), although the inorganic fine particles are firmly adhered to the toner and hardly pushed by selecting the kind of the release agent, the decrease in the toner charge amount is prevented. However, it was necessary to use a fluororesin having a high substitution ratio of a fluorine element as a carrier, and it was not possible to avoid that the surface resistivity of the carrier particles was increased and the developability was deteriorated.

When the techniques described in the above publications (2) and (3) are applied to a toner recycling system, the additives and the surface treatment agent on the toner are detached from the toner surface, resulting in a decrease in the charge amount and a long-term use. I can't stand it.

In order to apply the technology described in the above-mentioned publication (4) to a toner recycling system, only the carrier technology described in this patent changes the release agent on the toner surface and cannot control the change of the external additive, so that the developer cannot be controlled. Not withstand use as.

Further, in the technique described in the publication (5), when the magnetic material dispersed type carrier is applied to the toner recycling system, the recycled toner tends to adhere to the carrier and the durability as a developer becomes short. was there.

As a result of extensive studies, the present inventors have found that in a toner recycling system, the amount of release fluorine and the amount of external additives in the recycled toner particles are kept within a minimum range so that the amount of fluorine on the surface of the carrier particles can be adjusted to an appropriate range. It has been found that the carrier surface resistivity can be reduced and low potential development can be achieved, and the present invention has been completed.

The present invention has been proposed on the basis of the above circumstances, and it is an object of the present invention to provide an image forming method employing a toner recycling system which has excellent developability, low potential development, and high image quality. An object of the present invention is to provide a developer having durability performance.

Since the toner has minimal changes in the release agent component and the external additive (fluidity improver) component on the toner surface, even when subjected to a large stress due to a cleaning process, a recycling process, etc. There is no separation of the release agent from the toner surface, and there is no deterioration of the fixing roller stain.
Embedding of the external additive in the toner and detachment from the toner surface do not occur, and the charging performance of the toner itself does not always change. Therefore, the charge-imparting ability of the carrier surface coating material can be reduced, and the amount of the fluororesin can be reduced. As a result, the carrier resistance can be reduced, and development at a low potential can be performed.

[0017]

The above object is achieved by the following means.

(1) In an image forming method employing a toner recycling system, the change X in the amount of toner release agent
X = (heat of fusion due to release agent of recycled toner) /
(Heat of fusion caused by the release agent of New Toner)
0.9 ≦ X ≦ 1.0, and the change Y in the amount of the external additive of the toner
Where Y = (amount of external additive on the surface of the recycled toner) / (amount of external additive on the surface of the new toner), the toner satisfying 0.8 ≦ Y ≦ 1.0 and the ESCA of the resin coating carrier
Presence of surface fluorine element determined from intensity ratio of measured peaks
Image forming method which comprises using the developer resident amount consists of the carrier is 6-25% by number.

(2) In the image forming method described in (1), when the kneading temperature of the toner composition is lower than the melting point (Tm) of the release agent,
An image forming method, wherein the temperature is not lower than −40 ° C., and the filling ratio is controlled to 75 to 90% by using a high-speed stirring type mixer in the mixing step of the toner and the external additive.

According to the image forming method of the present invention, in the toner particles containing a binder resin, a colorant, a release agent and other additives as necessary, the content of the release agent in the recycled toner, the amount of the external additive, And the amount of elemental fluorine on the carrier surface (fluorine
(May be abbreviated as amount)), the range of the appropriate abundance was defined by J / g and the number% of each unit system based on the following measurement method.

In the present invention, the heat of fusion is measured by, for example, DSC-7 (manufactured by PerkinElmer) in accordance with the differential scanning calorimetry (DSC). Specifically, a 5 mg sample is heated at a constant heating rate. (10 ° C / min.)
It was calculated from the area surrounded by the baseline and the endothermic peak.

In the present invention, the amount of the external additive present on the surface of the toner particles and the amount of fluorine present on the surface of the carrier are ESCA1000.
(Manufactured by Shimadzu Corporation). The toner and carrier were rubbed into a sample dish (2 mm deep and 1 cm in diameter) with an X-ray (MgKα) output of 10.0 kV and 20.0 mA.
For quantitative calculation of surface components, carbon: C1s, oxygen: O1s, nitrogen: N1s, fluorine: F1s, silicon: Si2p, titanium: Ti2p
3/2, aluminum: Al2p, zirconium: Zr3d3 /
Using the peak of such 2,3d5 / 2, it was determined respective amounts from the peak area. Using these peak areas, was determined as the correction was carried out intensity ratio <br/> by sensitivity coefficient as an intensity correction by each element.

[0023]

Hereinafter, the present invention will be described in detail.

In the image forming method of the present invention, since the releasing agent and the external additive hardly change on the toner surface, the releasing agent and the external additive can be removed from the toner surface even in a developing device having a toner recycling system. It can withstand repeated use without falling off. When the change X in the amount of the toner release agent (where X = (the heat of fusion caused by the release agent of the recycled toner) / (the heat of fusion caused by the release agent of the new toner)) is less than 0.9, the toner surface The amount of release agent decreases, fixing performance deteriorates,
Does not withstand long-term use. On the other hand, the change Y in the toner external additive amount
If (Y = (amount of external additive on the surface of recycled toner) / (amount of external additive on the surface of new toner)) is less than 0.8, the charge amount is reduced and the product cannot be used for a long time.

The image forming method used in the present invention employs a toner recycling system to form an image. That is, it refers to a system in which the toner remaining on the photoreceptor without being transferred is collected by the cleaning unit, and the collected toner is returned to the developing device and / or the toner replenishing box for reuse.

FIG. 1 shows an example of an image forming method applicable to the image forming method of the present invention. 7 is a photosensitive member, the photosensitive member 7 has a form of a rotating drum-like, organic photoconductor, a metal light conductor, so-called Se-Te, preferably As ₂ Se _3, in particular of the easy disposability From the viewpoint, an organic photoreceptor is preferable. A charger 1, an exposure optical system 2, a developing unit 3, a transfer unit 5, a separator 6, and a cleaning unit 8 are arranged around the photoreceptor from the upstream side to the downstream side in the rotation direction. Ten
Is a fixing device.

In this image forming apparatus, the surface of the photoreceptor 7 is charged to a uniform potential by the charger 1 and then imagewise exposed by the exposure optical system 2 to form an electrostatic latent image on the surface of the photoreceptor 7. It is formed. Then, the above-described electrostatic latent image is developed by a developer containing a specific toner and a carrier, which will be described later, housed in the developing device 3 to form a toner image. This toner image is electrostatically transferred to the recording material P by the transfer device 5, and is heat-fixed by the heat roller fixing device 10 to form a fixed image. On the other hand, the photoreceptor 7 that has passed through the transfer unit 5 is cleaned of residual toner by a cleaning unit 8, and is used for forming the next image. Further, the toner collected in the cleaning device is returned to the developing device 3 and / or the toner replenishing box 11 again by a toner recycling system described later, and is reused.

FIG. 2 shows a specific example of the toner recycling system.
And 3. In this example, 12 is a developing device, 13 is a developing sleeve, 14 is a photoreceptor, 15 is a cleaning device, 16 is a toner conveying screw 1, 17 is a toner conveying screw 2, 18 is a toner conveying screw 3, and 20 is a toner supply box. is there. In the apparatus of this embodiment, the toner collected by the cleaning unit is sequentially conveyed by the toner conveying screws 1, 2, and 3, and the toner is supplied to a distributor 19 (separate from the new toner supply port) provided for the collected toner provided in the developing unit. It is intended to be supplied.
That is, the 16 toner conveying screws 1, the 17 toner conveying screws 2, and the 18 toner conveying screws 3 each have a rotating shaft inside and a blade provided spirally along the rotating shaft. The toner is sequentially conveyed by the blades with the rotation of the shaft, supplied to the distributor 19, and the collected toner is again used for developing the latent image on the photoconductor 14.

On the other hand, 12 to 18 and 20 in FIG.
In the apparatus of this embodiment, the toners collected by the cleaning unit are sequentially conveyed by the toner conveying screws 1, 2, and 3, and supplied to the toner supply box. This embodiment is different from FIG. 2 in that the new toner and the recycled toner collected in the toner supply box are stirred and mixed in advance and then supplied to the developing device.

The toner used in the present invention can be obtained by changing the amount of toner release agent X (X = (heat of fusion caused by the release agent of recycled toner) / (new toner) ) Satisfies 0.9 ≦ X ≦ 1.0, and a change Y (Y = (amount of surface external additive of recycled toner) / (new toner)) Is required to satisfy 0.8 ≦ Y ≦ 1.0.

The toner binder resin used in the present invention is not particularly limited.
Styrene-acrylate resin, styrene-methacrylate resin, styrene-butadiene resin, styrene-acrylonitrile resin, styrene-acryl-polyester resin, styrene-acryl-crystalline polyester graft resin, polyurethane resin, epoxy resin , Silicone resin, polyvinyl chloride, polyamide, polyvinyl butyral, rosin, modified rosin, phenol resin, xylene resin and the like.

In the toner base particles (excluding external additives, hereinafter referred to as colored particles), components such as a colorant, a charge control agent, a release agent, and a magnetic material are included as necessary in addition to the binder resin. It is. The amount of addition is not particularly limited, but 1 part to 50 parts each.
Parts are preferred.

As the coloring agent, for example, carbon black,
Nigrosine dye, aniline blue, coco oil blue, chrome yellow, Dupont oil red, quinoline yellow, phthalocyanine blue, malachite green oxalate, rose bengal, and the like, and mixtures thereof can be used.

Nigrosine dyes, 4
A quaternary ammonium salt compound, an alkylpyridinium compound and the like can be used.

As the release agent, for example, the melting point is from 100 ° C. to 140
° C is preferable, and the number average molecular weight (the number average molecular weight indicates a polystyrene molecular weight converted value by high temperature GPC)
Polyolefin wax such as low molecular weight polyethylene of 1500 to 5000, low molecular weight polypropylene, low molecular weight polyethylene-polypropylene copolymer, for example, micro wax, high melting point paraffin wax such as Fischer-Tropsch wax, for example, fatty acid lower alcohol ester, fatty acid higher alcohol ester And ester waxes such as fatty acid polyhydric alcohol esters and amide waxes.

As the magnetic substance, ferromagnetic metals or alloys such as ferrite and magnetite, cobalt, nickel and the like, or compounds containing these elements,
Alternatively, an alloy that does not contain a ferromagnetic element but exhibits ferromagnetism by performing an appropriate heat treatment, such as an alloy called a Heusler alloy containing manganese and copper, such as manganese-copper-aluminum and manganese-copper-tin, may be used. Can be done.

Further, these toner compositions are mixed, melt-kneaded, pulverized and classified, and inorganic fine particles (external toner additives) such as silica and titanium oxide are added from the viewpoint of improving the fluidity of the toner. Obtain toner particles.

As a result of intensive studies, the present inventors have found that the release agent component kneaded into the binder resin in the melt-kneading step is difficult to separate from the toner surface by controlling the conditions of the main kneading step. Was. That is, factors of the kneading conditions include the temperature of the kneading zone in the kneading machine, the mixing strength in the kneading zone, and the like. If the kneading temperature exceeds Tm with respect to the melting point (Tm) of the release agent, the melt viscosity of the release agent becomes extremely low, and as a result, the dispersion diameter of the release agent becomes small. On the other hand, if kneading is performed at a temperature lower than Tm-40 ° C., the release agent does not melt and is not uniformly kneaded into the binder resin, and as a result, the dispersion diameter of the release agent becomes uneven.

The external additive may be any as long as it can improve the fluidity of the toner, and may be hydrophilic silica, hydrophobic silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, titanic acid. Fine particles such as strontium, zinc oxide, chromium oxide, cerium oxide, antimony trioxide, and zirconium oxide can be given. Further, it is preferable to use an external additive that forms a secondary and tertiary aggregate having an effect of appropriately polishing the surfaces of the photoconductor and the carrier particles to prevent deterioration of the photoconductor and the developer. Examples thereof include silica treated with an amino-modified silicone oil and hydrophobic silica treated with an organosiloxane and 3-aminopropyltriethoxysilane.

The method of dispersing the external additive on the toner surface is as follows. The toner composition and the toner external additive are put into a high-speed stirring type mixer having one or two types of rotating blades inside and stirred at a high speed. The present inventors have made intensive studies and found that the filling ratio of the colorant particles and the external additive in the high-speed stirring type mixer is controlled to 75 to 90% in the main mixing step. As a result, it was found that the external additive was difficult to be separated from the toner surface. Here, the filling rate is defined by the following equation.

Filling rate = (mass of (colorant particles + fine particles of external additive) ÷ static bulk density of colorant) ÷ volume of high-speed stirring type mixer × 100
[%] Known mixers such as Henschel mixer (manufactured by Mitsui Miike), LMA5 (manufactured by Nara Kikai), and VG25 (manufactured by Fuji Sangyo) can be used as the high-speed stirring mixer.

As a resin for carrier coating, a fluorine-based resin having a low surface energy is widely used from the viewpoint of physical adhesion and prevention of carrier surface contamination. Specific examples of the fluororesin include polytetrafluoroethylene, ethylene tetrafluoride / ethylene hexafluoride copolymer, polytrifluoroethylene chloride, polyvinylidene fluoride, and tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer. A copolymer, a vinylidene fluoride-tetrafluoroethylene copolymer, a fluorine-containing resin having a group in which a fluorine atom is substituted in a side chain, a copolymer with styrene and a vinyl polymer, and the like can be used. Among the fluorine-containing resins, in particular, 1,1,3-trihydroperfluoro-n-propyl acrylate and 1,1-
Preferred are dihydroperfluoro-n-propyl acrylate copolymer, 1,1-dihydroperfluoroethyl acrylate polymer, and 2,2,2-trifluoroethyl methacrylate polymer.

[0043]

EXAMPLES The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, "part" represents a weight part.

(Example 1) Binder resin: 100 parts of polyester resin Colorant: 8 parts of carbon black Release agent: Low molecular weight polypropylene (melting point: 140 ° C.) 4 parts The above materials were mixed with a Henschel mixer and twin-screw extruded. Kneading using a kneader (extruder) at a kneading unit temperature of 110 ° C., coarsely pulverizing the kneaded material, finely pulverizing with a mechanical pulverizer, and classifying with an air classifier to obtain colored particles A having a volume average particle size of 10 μm. Obtained. To 100 parts of the obtained colored particles A, 1.0 part of hydrophobic silica whose surface was treated with an organosiloxane and 3-aminopropyltriethoxysilane was added and mixed with a Henschel mixer so as to obtain a filling rate of 85%. Toner A was obtained. The amount of silica on the surface of the toner A determined by ESCA was 7.0% by number, and the heat of fusion was 0.80 J / g.

On the other hand, as a carrier, a copolymer of 2,2,2-trifluoroethyl methacrylate and styrene (copolymerization ratio
20:80 parts by weight) and a carrier A coated with a resin. In the surface analysis of this carrier by ESCA, the surface fluorine content was 8% by number.

An electrophotographic copying machine U-BIX 3035 manufactured by Konica Corporation was modified so that the developer comprising the toner A and the carrier A was modified to have a mechanism (see FIG. 3) for returning the recycled toner to the toner supply box. The actual shooting evaluation was carried out.

A part of the recycled toner collected in the cleaning device was taken out, and the heat of fusion and the amount of surface silica were quantified. As a result, X = 0.94 when the heat of fusion was 0.75 J / g, and Y = 0.88 when the amount of surface silica was 6.2% by number.
Further, even when the actual image evaluation was continued, there was no large change in these values, and no fogging or fixing failure occurred. The density of the obtained image maintained a relative density of 1.3 or more from the start, and did not change even after 30,000 copies.

Example 2 Binder resin; styrene-acrylic ionomer resin 100 parts Colorant; carbon black 10 parts Release agent; polyolefin wax (melting point 100 ° C.) 4 parts The above materials were mixed with a Henschel mixer. Kneading using a screw extruder (extruder) at a kneading point temperature of 110 ° C, coarsely pulverizing the kneaded material, finely pulverizing with a mechanical pulverizer, classifying with an air classifier, and coloring with a volume average particle size of 9 μm Particle B was obtained. Hydrophobic silica, the surface of which was treated with an amino-modified silicone oil, was added to 100 parts of the obtained colored particles B in an amount of 0.
Eight parts were added and mixed with a Henschel mixer so that the filling rate became 75%, to obtain a toner B. The toner B had a surface silica amount of 5.0% by number and a heat of fusion of 1.05 J / g.

On the other hand, a carrier B coated with a resin comprising a copolymer of 2,2,2-trifluoroethyl methacrylate and methyl methacrylate (copolymerization ratio 60:40 parts by weight) was used as the carrier. In the surface analysis of this carrier by ESCA, the surface fluorine content was 20% by number.

An electrophotographic copier U-BIX X2125 manufactured by Konica Corp. modified so as to have a mechanism (see FIG. 2) for returning the toner, which has been cleaned of the developer comprising the toner B and the carrier B, directly to the developing device. Was used to evaluate the actual photograph.

A part of the toner collected in the cleaning device was taken out, and the heat of fusion and the amount of surface silica were quantified. As a result, the heat of fusion was 0.95 J / g, X = 0.90, the amount of surface silica was 4.7% by number, and Y = 0.94. Furthermore, even if the live-action evaluation was continued, there was no large change in these values, and the occurrence of fog,
Also, no fixing failure occurred. The density of the obtained image maintained a relative density of 1.3 or more from the start, and did not change even after 30,000 copies.

(Example 3) Binder resin; 100 parts of styrene-acryl-polyester blend resin Colorant: 10 parts of carbon black Release agent: Low molecular weight polypropylene (melting point: 130 ° C.) 3 parts The mixture was kneaded using a twin-screw extruder (extruder) at a kneading temperature of 125 ° C., and after coarsely pulverizing the kneaded material, finely pulverizing with a mechanical pulverizer and classifying with an air classifier to obtain a volume average particle size. 9 μm colored particles C were obtained. 1.2 parts of hydrophobic silica, the surface of which was treated with organosiloxane and 3-aminopropyltriethoxysilane, was added to 100 parts of the obtained colored particles C and mixed with a Henschel mixer so that the filling ratio became 88%. Thus, a toner C was obtained. The amount of silica on the surface of the toner C was 8.5% by number, and the heat of fusion was 0.75 J / g.

On the other hand, a carrier C coated with a resin composed of a copolymer of 1,1-dihydroperfluoroethyl acrylate and methyl methacrylate (copolymerization ratio 50:50) was used as the carrier. In the surface analysis of this carrier by ESCA, the surface fluorine content was 17% by number.

An electrophotographic copier U-type manufactured by Konica Corporation having a mechanism for returning the toner having been cleaned of the developer comprising toner C and carrier C to the toner supply box.
Real-image evaluation was performed using BIX1520.

A part of the recycled toner collected in the cleaning device was taken out, and the heat of fusion and the amount of surface silica were quantified. As a result, the heat of fusion was 0.70 J / g, X = 0.93, the amount of surface silica was 7.0 number%, and Y = 0.82. Further, even when the actual image evaluation was continued, there was no large change in these values, and no fogging or fixing failure occurred. The density of the obtained image was maintained at 1.3 or higher in relative density from the start, and 3
There was no change after 000 copies.

Comparative Example 1 Binder resin; 100 parts of styrene-acrylic ionomer resin Colorant: 10 parts of carbon black Release agent: polyolefin wax (melting point: 100 ° C.) 4 parts The above materials were mixed with a Henschel mixer. Kneading using a screw extruder (extruder) at a kneading unit temperature of 150 ° C, coarsely pulverizing the kneaded material, finely pulverizing with a mechanical pulverizer, classifying with an air classifier, and coloring with a volume average particle size of 10 μm Particle D was obtained. Hydrophobic silica whose surface was treated with an amino-modified silicone oil was added to 100 parts of the obtained colored particles D in an amount of 0.
Eight parts were added and mixed with a Henschel mixer so that the filling ratio became 78%, to obtain a toner D. The toner D
Had a surface silica content of 5.0% by number and a heat of fusion of 1.25 J / g.

On the other hand, a carrier B coated with a resin comprising a copolymer of 2,2,2-trifluoroethyl methacrylate and methyl methacrylate (copolymerization ratio 60:40 parts by weight) was used as the carrier. In the surface analysis of this carrier by ESCA, the surface fluorine content was 20% by number.

An electrophotographic copier U-type manufactured by Konica Corporation having a mechanism for returning the toner, which has been cleaned of the developer comprising toner D and carrier B, to the toner supply box.
Real-image evaluation was performed using BIX1520.

A part of the recycled toner collected in the cleaning device was taken out, and the heat of fusion and the amount of surface silica were quantified. As a result, the heat of fusion was 1.02 J / g, X = 0.82, the amount of surface silica was 4.7% by number, and Y = 0.94. Fixing failure occurs after 3000 copies when the amount of recycled toner is considered to be steady, and the density of the obtained image is 1.1% in relative density.
It fell below.

(Comparative Example 2) Binder resin; polyester resin 100 parts Coloring agent: carbon black 10 parts Release agent: low molecular weight polypropylene (melting point: 130 ° C) 3 parts Kneading using a kneader (extruder) at a kneading unit temperature of 120 ° C., coarsely pulverizing the kneaded material, finely pulverizing with a mechanical pulverizer, classifying with an air classifier, and coloring particles having a volume average particle size of 8.5 μm E was obtained. To 100 parts of the obtained colored particles E, 1.0 part of hydrophobic silica whose surface was treated with an organosiloxane and 3-aminopropyltriethoxysilane was added, and the mixture was mixed with a Henschel mixer so that the filling rate became 60%. Thus, a toner E was obtained. Toner E had a surface silica amount of 7.0 number% and a heat of fusion of 0.97 J / g.

On the other hand, a carrier D coated with a resin composed of a copolymer of trifluoroethylene and styrene (copolymerization ratio 35:65 parts by weight) was used. In the surface analysis by ESCA of this carrier, the surface fluorine content was 10%.
It was a number%.

Actual image evaluation was performed using an electrophotographic copying machine U-BIX 3035 manufactured by Konica Corporation modified so as to have a mechanism for returning the cleaned toner containing the toner E and the carrier D to the toner supply box. Was done.

A part of the recycled toner collected in the cleaning device was taken out, and the heat of fusion and the amount of surface silica were quantified. As a result, the heat of fusion was 0.90 J / g, X = 0.93, the amount of surface silica was 3.2% by number, and Y = 0.46. When the evaluation of actual photographing was further continued, the charge amount of the toner decreased sharply after 5000 copies, toner scattering occurred, and the inside of the copying machine was contaminated.

(Comparative Example 3) Development consisting of the toner particles A described in Example 1 and a carrier E coated with 2,2,2-trifluoroethyl methacrylate polymer resin (the surface fluorine content by ESCA is 33% by number). Actual image evaluation was performed using an electrophotographic copying machine U-BIX 1520 manufactured by Konica Corporation having a mechanism for returning the toner from which the agent was cleaned to the toner supply box.

A part of the recycled toner collected in the cleaning device was taken out, and the heat of fusion and the amount of surface silica were quantified. As a result, the heat of fusion was 0.73 J / g, X = 0.91, the amount of surface silica was 5.8% by number, and Y = 0.83. But,
Developability was poor from the start, and the image density was 1.0 or less.

(Comparative Examples 4 to 9) Under the conditions of Example 1, the toner and carrier production conditions were controlled.
Developers as shown in the following table were prepared. Example 1 using this
Table 1 shows the results of the same performance evaluation.

[0067]

[Table 1]

[0068]

According to the present invention, the change in the amount of the releasing agent in the toner is small and the holding performance of the external additive is good, so that the surface property of the toner is maintained and the external additive and the toner binder resin adhere to the carrier. Hateful. Therefore, the amount of fluororesin on the carrier surface can be reduced, the carrier resistance is reduced, the developability is improved, and low potential development is possible, and the durability is also improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a copying machine to which the present invention is applied.

FIG. 2 is a diagram illustrating a toner recycling system used in the present invention.

FIG. 3 is a diagram illustrating a toner recycling system used in the present invention.

[Explanation of symbols]

 12 Developing unit 14 Photoconductor 15 Cleaning unit 16 Toner transport screw 1 17 Toner transport screw 2 20 Toner supply box

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G03G 15/08 112 G03G 9/08 381 21/10 21/00 326 (56) References JP-A-4-274247 (JP, A JP-A-5-45925 (JP, A) JP-A-4-358159 (JP, A) JP-A-4-100055 (JP, A) JP-A-6-11889 (JP, A) 190248 (JP, A) JP-A-5-80590 (JP, A) JP-A 1-234859 (JP, A) JP-A-2-61649 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/08 G03G 9/10

Claims (2)

(57) [Claims] In an image forming method employing a toner recycling system, a change X in a release agent amount of a toner is represented by: X = (heat of fusion caused by a release agent of a recycled toner) /
(Heat of fusion caused by the release agent of New Toner)
When 0.9 ≦ X ≦ 1.0 is satisfied and the change Y of the external additive amount of the toner is Y = (the external additive amount of the surface of the recycled toner) / (the external external additive amount of the new toner), 0.8 ≦ Y Toner satisfying ≦ 1.0 and peak measured by ESCA of resin-coated carrier
An image forming method comprising using a developer comprising a carrier having a surface fluorine element content of 6 to 25% by number determined from the intensity ratio of (1) . 2. The image forming method according to claim 1, wherein
When the kneading temperature of the toner composition is lower than the melting point (Tm) of the release agent,
Tm-40 ° C, not lower than 75 ° -90% using a high-speed stirring mixer in the mixing process of toner and external additives
And an image forming method.