JP2003280460A - Electrostatic latent image developing method and developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic latent image developing method which forms an image without any sticking carrier on it, can reproduce thin lines and uniformly reproduce small-diameter dots, and uses a two-component developer. <P>SOLUTION: In this developing method, at least one electrostatic charge latent image carrier is used and electrostatically charged, and then a developer carrier carrying the two-component developer is put close to the latent image carrier in parallel; while the developer carrier surface and latent image carrier surface are moved relatively at different speeds, an electric field is produced between both to develop a toner on the latent image carrier. This developing process is carried out by using two developing means. At this time, an electrostatic charging means, a developing means D1, a developing means D2, and a transfer means are provided in order from the upstream side in the moving direction of the latent image carrier; and the developing means D1 develops a non-image part with a toner T1 containing no coloring agent and the developing means D2 develops an image part with a toner T2 containing a coloring agent. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrostatic latent image developing method and a developer.

[0002]

2. Description of the Related Art In an electrostatic charge image developing device such as a copying machine or a printer which uses an electrophotographic system, various studies have been made to improve its printing speed and image reproducibility. Particularly in recent years, in order to improve the image quality, the density of pixels has been increased and the diameter of dots has been reduced, and more uniform and highly accurate development has been required. In a developing method using a so-called two-component developer, which is composed of a magnetic carrier and a fine particle toner, which are generally widely used, the toner is mixed with the carrier and supplied to the latent image. If the size is not sufficiently smaller than the minimum unit (dot diameter) of, the toner supply may become uneven, resulting in missing dots and variations in dot diameter, and impairing image resolution and gradation. was there.

However, reducing the carrier particle size in the two-component development can be expected to improve the image quality, but the magnetic moment per carrier particle inevitably decreases. The holding power becomes small, and the problem that the carrier adheres to a part of the image (hereinafter referred to as carrier adhesion) occurs. Such carrier attachment is
The toner in the developer is consumed while the developer passes through the developing nip, or the toner in the developer moves toward the developer carrier (sleeve) due to the electric field at the background portion of the latent image. In most cases, the carrier in the vicinity of the image has an electric charge having the opposite polarity to that of the toner, and the carrier is developed at the background portion, particularly at the edge portion where a reverse electric field occurs near the latent image. As a result, carrier adhesion tends to occur around the character portion, the thin line portion, the rear end of the high-density image portion, and the like.

[0004]

SUMMARY OF THE INVENTION The present invention provides a developing method and a developer capable of solving the above-mentioned conventional problems, that is, without causing carrier adhesion.
An object of the present invention is to provide an electrostatic latent image developing method and a developer capable of fine line reproducibility and uniform reproduction of small-diameter dots, and having excellent resolution and gradation.

[0005]

A first aspect of the present invention is to use at least one electrostatic latent image carrier, a charging means for charging the electrostatic latent image carrier, and a carrier having magnetism with respect to the electrostatic latent image carrier. And a developer carrying member carrying a developer composed of non-magnetic toner are brought close to each other in parallel, and the surface of the developer carrying member and the surface of the electrostatic latent image carrying member are moved relatively at different speeds, and electrostatic charges are generated. Two developing means for developing an electric field between the surface of the latent image carrier and the developer carrier to develop the toner on the electrostatic latent image carrier, and the toner developed on the electrostatic latent image carrier. A developing method that uses a transfer unit that transfers an image to a transferred member,
From the upstream side with respect to the moving direction of the electrostatic latent image carrier, in order,
A charging unit, a developing unit D1, a developing unit D2, and a transfer unit are provided, the developing unit D1 develops a non-image portion with a toner T1 containing no colorant, and the developing unit D2 uses a toner T2 containing a colorant. An electrostatic latent image developing method characterized by developing an image portion.

In the second developing method of the present invention, the developer used in the developing means D2 comprises a carrier containing at least a magnetic substance having a weight average particle diameter of 10 to 25 μm and the toner T2. The electrostatic latent image developing method is characterized in that

A third aspect of the present invention is, in the first or second developing method, the toner T1 and the toner T2 have different charge amounts, and the toner T2 has a charging polarity of the electrostatic latent image carrier. The electrostatic latent image developing method is characterized by having the same polarity as the charging polarity.

A fourth aspect of the present invention is the method for developing an electrostatic latent image according to any one of the first to third aspects, wherein the weight average diameter of the carrier of the developing means D1 is 35 μm or more. Is.

A fifth aspect of the present invention is the developing method according to any one of the first to fourth aspects, wherein the developer contained in the developing means D2 has a toner coverage of 25 to 50% on the carrier. The electrostatic latent image developing method is characterized by the following.

A sixth aspect of the present invention is the developing method according to any one of the first to fifth aspects, wherein the direct current resistance of the carrier is 1 × 1.
0 ⁸ is a electrostatic latent image developing method, wherein it is Ωcm or more.

In a seventh aspect of the present invention, in the developing method according to any one of the first to sixth aspects, the carrier is coated with a silicone polymer having Si--O as a main repeating unit. This is an image developing method.

In an eighth aspect of the present invention, in the developing method according to any one of the first to seventh aspects, the toner T2 contained in the developing means D2 contains a colorant selected from yellow, magenta, cyan and black. The electrostatic latent image developing method is characterized by the following.

The ninth aspect of the present invention is magnetic and has a true specific gravity of 2.
It contains a substantially spherical carrier having a weight average particle diameter of 5 to 6 g / cm ³ of 10 to 25 μm and a coloring agent selected from any of yellow, magenta, cyan and black, and the weight average particle diameter of the coloring agent is 1/2 to 1 of the weight average diameter of the carrier
The electrostatic latent image developer is characterized in that it is / 10.

The electrostatic latent image developing method of the present invention is described below.
This will be described with reference to the drawings. FIG. 1 is a partial sectional view of an example of an image forming apparatus using the method of the present invention. As shown in FIG. 1, the developing means in the present invention is a charging unit G1 for charging the latent image carrier P1 which is an endless belt-shaped or cylindrical rotating latent image carrier P1 and two developing units (D).
1, D2) to develop the latent image on P1 with toner (T1, T2) of each developing unit. The developed toner image is transferred to the transfer target Pa by the transfer device Tr1.

The developing unit for developing the image portion is the developing unit D2 arranged on the downstream side with respect to the moving direction of the surface of the latent image carrier, and the developing unit D1 is for the non-image portion (the background portion of the image). To develop. for that reason,
Colored toner is used as the toner T2 of the developing unit D2,
A colorless toner is used as the toner T1 of the developing unit D1.

The developing method used in the developing unit D1 may be any developing method, for example, non-magnetic one-component development consisting of colorless toner and a toner carrier carrying toner, or two-component development using carrier and toner. However, the developing unit D1 consumes a relatively large amount of toner as compared with the developing unit D2 because the developing unit D1 develops the background portion. Therefore, it is preferable to use the two-component developing method which is advantageous in the toner supply amount. On the other hand, in the developing unit D2, a two-component developer including a carrier and a color toner is used. The two-component developer in the developing unit D2 is a developer composed of non-magnetic toner and carrier, and develops the latent image in the image area. That is, an image formed by the toner T1 and the toner T2 is formed on the latent image carrier P1 by one developing operation.

As described above, since the latent image portion (image portion) is developed after the background portion (non-image portion) around the image portion is developed with the toner T1, the latent image has been a problem in electrophotography. Image density fluctuation (edge effect) due to disturbance of the electric field at the image edge, density unevenness at the image edge due to the developer rubbing the non-image area (edge loss), and charge up to the polarity opposite to the toner due to development It is possible to drastically improve the problems such as carrier adhesion and the like in which the formed carrier develops in the non-image area of the latent image. As a result, it becomes possible to use a carrier having an extremely small particle diameter, which has been difficult to use due to the occurrence of carrier adhesion in the related art, and the sharpness and uniformity of the image can be greatly improved.

When the magnetic brush of the developer is brought into contact with the latent image carrier in the D2 unit to perform the development, the toner T1 image on the background portion developed in the D1 unit is rubbed by the magnetic brush of the D2 unit. But T
By setting the absolute value of the charge amount of 1 to be smaller than the absolute value of the charge amount of T2, it is possible to prevent the toners T1 and T2 from adhering to each other during rubbing to cause background stain. Also,
It is also possible to develop by substantially contacting and separating the D2 unit from the latent image carrier. The particle size of the carrier used in the D2 unit for forming a visible image depends on the particle size of the toner used, but it is preferable that the particle size is larger than the toner and the particle size is as small as possible within the range where carrier adhesion does not occur. An average particle size of 10 to 25 μm is preferably used.

Further, the toner in each developer is adjusted to have a preferable charge amount for developing the non-image area and the image area. That is, the charging potential of the latent image carrier (dark portion potential Vd) and the potential of the exposed portion (light portion potential Vl)
Applying a DC bias potential or an AC bias potential of an intermediate magnitude to the developer carrier, exposing the portion corresponding to the image to lower the potential, and performing reverse development by developing with the previous bias potential. Is the most common and D
The charging polarity of the two units of toner T2 is preferably the same as the charging polarity of the latent image carrier. In general, an organic photoconductor that uses an organic pigment as a carrier-forming material as a latent image carrier is often charged with a negative charge. In this case, the toner T2 of the D2 unit has a negative charge, and the toner T1 of the D1 unit has a negative charge. The charge amount of is positive.

In the developing unit D2, it is important to make the electric resistance of the carrier proper. If the electric resistance of the carrier is too low, the carrier has an induced charge due to the potential difference between the image area and the developing bias, and carrier adhesion occurs. This is carrier adhesion that is often seen especially in the image area, but it is difficult to prevent carrier adhesion to the image area due to this induction even when the two developing units of the present invention are used. Therefore, the direct current resistance of the carrier is preferably 1 × 10 ⁸ Ωcm or more.

On the other hand, in the developing unit D1, the background portion, which is a non-image portion, is developed with colorless toner, and this development should not cause problems such as carrier adhesion. Therefore, it is possible to use a carrier slightly larger than the developer in the developing unit D2, and the preferable carrier particle size is 3 in terms of weight average particle size.
It is 5 μm or more.

[0022]

Next, the developing method of the present invention will be described more specifically. In order to more precisely supply the toner to the latent image, it is preferable that the carrier particle diameter is small and the toner content is relatively large. Regarding the content of the toner in the developer, the coverage of the toner with respect to the carrier is used in the range of 20 to 90%, more preferably 25% to 50%. By setting the coverage ratio of the toner on the carrier to be less than 90%, it is possible to impart a uniform charge amount even when the toner is not charged properly, particularly when the toner concentration is temporarily increased such as when replenishing the toner.

The toner coverage as referred to herein is determined by the following method. That is, the particle size of the toner and the carrier is subdivided into predetermined particle size ranges, and the sum is calculated with respect to (total projected area of toner) / (total surface area of carrier) calculated in each subdivided region. The ratio is calculated from (total actual projected area of toner) / (total actual surface area of carrier).
By this method, a value close to a substantial coverage can be calculated regardless of the particle size distribution of the toner or carrier.

First, the particle size distribution of the toner is measured using a Coulter counter to obtain 256 ch histogram data. Using the toner representative particle size Rt for each channel (average value of the particle sizes at the upper and lower ends of the channel) and the number of toner particles included in the channel region nt, the projected area x number of spheres of the representative particle size is calculated, and the value is calculated. Sum of all channels of
Set to 1. s1 = Σ (π (Rt / 2) ² × nt). Next, the particle mass x number of the representative particle size of each channel is calculated, and the total of all the channels is set to w1. w1 = Σ (4 / 3π (Rt / 2) ³ × σt × nt). Here, σt represents the true specific gravity of the toner. From the above, using s1 and w1, (total projected area per 1 g of toner) = s1 × (1 g / w
1) is introduced.

Similarly, the total surface area of the carrier is also collected as histogram data in which the particle size of the carrier is measured by Microtrac and divided into particle size distributions of 2 μm. Similarly, using the carrier representative particle diameter Rc (average value of the particle diameters at the upper and lower ends of the channel) for each channel and the number of carriers nc contained in the channel region, the surface area x number of spheres having a representative particle diameter is obtained, Let that value be the sum of all channels s2. s2 = Σ (4π (Rc / 2) ² × nc) × nc. Next, the particle mass x number of the representative particle size of each channel is obtained, and the total of all the channels is set to w2. w2 = Σ (4 / 3π (Rc / 2) ³ × σc × nc). Here, σc represents the true specific gravity of the carrier. From the above, using s2 and w2, (total surface area per 1 g of carrier) = s2 × (1 g / w
2) is introduced.

The coverage Tn is expressed as Tn = (total projected area per 1 g of toner) × Mt / (total projected area per 1 g of carrier) × Mc where Mt is the total mass of the toner and Mc is the total mass of the carrier. Therefore, when the toner density is C%, the above 2
Using the formula, the following formula (1) is obtained. (C = Mt
/ (Mt + Mc)) Coverage Tn = C · St / (1-C) · Sc × 100 (1) where St = total projected area per 1 g of toner Sc = total surface area per 1 g of carrier C = toner concentration

Next, the carrier material that can be used in the present invention will be described. A conventionally known carrier core material can be used. Examples thereof include ferromagnetic materials such as iron and cobalt, magnetite, hematite, Li-based ferrite, Mn-Zn-based ferrite, Mn-Mg-based ferrite, Cu-Zn-based ferrite, Ni-Zn-based ferrite and Ba ferrite. The above-mentioned magnetic particles are generally used as the carrier core material, but since a carrier having a smaller particle size is obtained, magnetic particles prepared by dispersing magnetic powder in another binder resin are used. It is also preferable to use a resin dispersion carrier. As the binder resin used for the resin dispersion carrier, known resins such as acrylic resin and polyester resin are used, and among them, phenol resin is more preferable because it has excellent mechanical strength.

The surface of the carrier is preferably coated with a low surface energy substance in order to prevent adsorption and adhesion of toner constituent materials and to reduce adsorption of moisture in the air. As the low surface energy substance, there are the following conventionally known materials. Polytetrafluoroethylene (PTFE), perfluoroalkoxy / fluorine resin (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene Examples thereof include ethylene fluoride (PCTFE), vinylidene fluoride (PVDF), vinyl fluoride (PVF), polyimide resin, styrene resin, and acrylic resin. It can also be used as a mixture of two or more selected from these.

As the low surface energy substance, particularly Si
A silicone polymer having —O as a main repeating unit can be preferably used. Examples of the silicone compound having Si—O as a basic repeating unit include a silicone resin containing a repeating unit represented by the following general formula.

[0030]

[Chemical 1] In the above formula, R represents a hydrogen atom, a halogen atom, a hydroxy group, a methoxy group, a C ₁ -C ₄ lower alkyl group or a phenyl group.

As the straight silicone resin, for example, KR271, KR272, KR282, KR25.
2, KR255, KR152 (Shin-Etsu Chemical Co., Ltd.), S
R2400, SR2406 (manufactured by Toray Dow Corning Silicone Co., Ltd.) and the like.

Examples of the modified silicone include epoxy-modified silicone, acryl-modified silicone, phenol-modified silicone, urethane-modified silicone, polyester-modified silicone and alkyd-modified silicone. Examples thereof include epoxy-modified: ES-1001N, acrylic-modified: KR-5208, polyester modified: KR-
5203, alkyd modified: KR-206, urethane modified: KR-305 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), epoxy modified: SR2115, alkyd modified: SR2110.
(Toray Dow Corning Silicone Co.).

Furthermore, the dispersibility of the silicone resin and the additive,
Generally known silane coupling agents can be included to improve compatibility. Examples of the silane coupling agent include those represented by the following general formula.

[Chemical 2] In the above formula, n means an integer of 1 to 3, X means various functional groups having reactivity or adsorptivity with organic or inorganic substances, and saturated or unsaturated hydrocarbon chains having functional groups. X
When a plurality of exist, they may be different from each other. O
R means an alkoxy group. Of the silane coupling agents represented by the above formula, a so-called aminosilane coupling agent having an amino group in X is preferably used.

The aminosilane coupling agent that can be used in the present invention includes those exemplified below.

[Chemical 3]

[0035]

[Chemical 4]

Further, the resistance is adjusted in the coating layer (coating resin),
The following substances can be added to improve the film strength. If necessary, one or more kinds may be used in an appropriate amount. It conductive ZnO, metal powder such as Al, SnO ₂ doped with SnO ₂ and various elements made by various methods, borides, eg _TLB 2, Zn
B _2, MoB _2, silicon and conductive polymers carbide (polyacetylene, polyparaphenylene, poly (para - phenylene sulfide), polypyrrole), and carbon black. A known method such as a spray drying method, a dipping method, or a powder coating method can be used as the method for forming the coating resin.

The particle size of the toner is preferably as small as possible in order to obtain high image resolution. The particle size of the toner is appropriately selected with respect to the carrier particle size to be used, and 7 μm or less is preferably used in the present invention.
In particular, the color toner used in the developing unit D2 preferably has a fine particle diameter, and the weight average diameter thereof is 3 to 6.
More preferably, it is μm.

The toner used in the present invention contains a thermoplastic resin as a binder resin as a main component, and contains a colorant, fine particles, a charge control agent, a release agent and the like. Further, a toner prepared by various toner manufacturing methods such as a generally known pulverization method and polymerization method can be used.

As the binder resin, polystyrene,
Homopolymers of styrene such as polyvinyltoluene and its substitution products, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-methyl acrylate copolymers, styrene- Ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-o-
Methyl chloroacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isobutylene copolymer, styrene-malein Acid copolymers, styrene copolymers such as styrene-maleic acid ester copolymers, polymethylmethacrylate, polybutylmethacrylate,
Polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic series Petroleum resin, chlorinated paraffin, paraffin wax and the like can be used alone or in combination.

Among the binder resins, the polyester resin is obtained by the polycondensation reaction of alcohol and acid.
Examples of alcohols include polyethylene glycol, diethyl glycol, triethylene glycol,
Diols such as 1,2-propylene glycol, 1,3-propylene glycol, 1,4-propylene glycol, neopentyl glycol and 1,4-butenediol, 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, Etherified bisphenols such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropyleneized bisphenol A, etc., and a divalent alcohol unit amount obtained by substituting these with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms. Body, other dihydric alcohol monomers, sorbitol, 1, 2,
3,6-hexanetetrol, 1,4-salbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2- Methylpropanetriol, 2-methyl-1,
Examples include higher alcohol monomers having a valence of 3 or more, such as 2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

The carboxylic acid used to obtain the polyester resin includes, for example, palmitic acid, stearic acid, oleic acid and other monocarboxylic acids, maleic acid, fumaric acid, mesaconic acid, citraconic acid, terephthalic acid, cyclohexanedicarboxylic acid, Succinic acid, adipic acid, sebacic acid, malonic acid, divalent organic acid monomers in which these are substituted with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms, anhydrides of these acids, and lower alkyl esters Dimers from linoleic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,
5,7-naphthalene tricarboxylic acid, 1,2,4-naphthalene tricarboxylic acid, 1,2,4-butane tricarboxylic acid, 1,2,5-hexane tricarboxylic acid, 1,3-
Dicarboxylic acid-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,
Examples thereof include 2,7,8-octanetetracarboxylic acid embol trimer and trivalent or higher polyvalent carboxylic acid monomers such as anhydrides of these acids.

Among the binder resins, examples of epoxy resins include polycondensates of bisphenol A and epichlorohydrin. For example, Epomic R362 and R36.
4, R365, R366, R367, R369 (all manufactured by Mitsui Petrochemical Co., Ltd.), Epotote YD-011, YD
There are commercially available products such as -014, YD-904, YD-017 (all manufactured by Tohto Kasei Co., Ltd.) and Epocoat 1002, 1004, 1007 (all manufactured by Shell Chemical Co., Ltd.).

The colorant used for the color toner is the three primary colors used for subtractive color mixing, which are suitable for forming a full-color image, that is, each color of yellow, magenta, and cyan, and any of four colors to which a black toner is added. Is used.

As the colorant, carbon black, lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, phthalocyanine blue, Hansa yellow G, rhodamine 6G lake, calco oil blue, chrome yellow, quinacridone, benzidine yellow, rose bengal Any known dyes and pigments such as triallylmethane dyes, monoazo dyes, disazo dyes and dyes may be used alone or in combination.

There is no inconvenience even if the toner contains a drug to be contained for the purpose of controlling the triboelectrification property, as in the case of a commonly used toner. As such a so-called polarity control agent, for example, a metal complex salt of a monoazo dye,
Nitrohumic acid and its salts, salicylic acid, naphthoic acid,
Metal complexes of dicarboxylic acid such as Co, Cr, and Fe can be used alone or in combination, but are not limited thereto. The polarity control agent used for the colorless toner needs to be colorless, and a polar polymer-type polarity control substance is preferably used.

A fluidity modifier may be added to the toner used in the present invention. Examples of fluidity modifiers include organic resin fine particles, metal soaps, Teflon (registered trademark), lubricants such as zinc stearate, or abrasives such as cerium oxide and silicon carbide, generally for the purpose of fluidity modification. Known metal oxides used for the above, typically, metal oxide fine particles such as silicon oxide, titanium oxide, and aluminum oxide, and particles whose surface is hydrophobized. Hydrophobicizing the surface of any of these fine powders brings about an excellent effect in terms of fluidity. In order to hydrophobize the surface, for example, a silicon compound generally known as a silane coupling agent or a silylating agent can be brought into contact with and reacted with the particle surface.

Examples of the hydrophobizing agent include chlorosilanes, and typically, trichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, ethyldichlorosilane, diethylchlorosilane, triethylchlorosilane, propyldichlorosilane and dichlorosilane. Alkylchlorosilanes such as propyldichlorosilane and tripropylchlorosilane, phenylchlorosilanes, and the like, and fluorine-substituted products thereof include fluoroalkylchlorosilanes and perfluoroalkylchlorosilanes. Typical examples of the silylamines include hexamethyldisilazane, diethylaminotrimethylsilane, diethylaminotrimethylsilane and the like.
Typical examples of the silylamides include N, O-bistrimethylsilylacetamide, N-trimethylsilylacetamide, and bistrimethylsilyltrifluoroacetamide. Further, as alkoxysilanes, methyltrialkoxysilane, dimethyldialkoxysilane, trimethylalkoxysilane, ethyldialkoxysilane, diethylalkoxysilane, triethylalkoxysilane, propyltrialkoxysilane, dipropyldialkoxysilane, tripropylalkoxysilane, etc. And alkylphenylsilanes having a phenyl group, and fluorine-substituted compounds thereof include fluoroalkylalkoxysilanes and perfluoroalkylalkoxysilanes.
In addition, as silicone oil, dimethyl silicone oil and its derivatives, fluorine-substituted compounds, disiloxane, hexamethyldisiloxane, siloxanes, etc.,
All of the compounds commonly used as a hydrophobizing agent can be used.

Hereinafter, the present invention will be described more specifically by way of examples. However, the present embodiment is only one aspect of the present invention, and the present invention is not limited to these embodiments. In addition, all the component amounts (parts) shown in the following examples are based on weight.

Reference Example 1 (Core Material of Carriers A to E) First, the same core material was used as the core material of each of the carriers A to E used in the developer, and air classification and mesh classification were performed. Ferrite core materials 1 to 4 were obtained. Ferrite core 1 Magnetic moment σs = 65 emu / g, weight average particle size 5
1.9 μm ferrite core material 2 magnetic moment σs = 65 emu / g, weight average particle diameter 3
8.1 μm Ferrite core 3 Magnetic moment σs = 65 emu / g, weight average particle size 2
4.4 μm Ferrite core 4 Magnetic moment σs = 65 emu / g, weight average particle size 1
5.6 μm Then, a silicone coating was formed on each core material as in Carrier Production Examples AE described later.

The magnetic moment and the weight average particle diameter of the carrier core material were measured as follows. (1) A magnetic moment was measured by using a multi-sample rotary magnetization measuring device REM-1-10 manufactured by Toei Industry Co., Ltd.
It was measured at 0 Oe (about 79578 A · m). (2) The weight average particle diameter is the weight standard diameter measured by Microtrac.

Production Example of Carrier A Carbon (Ketjen Black EC-DJ600, manufactured by Lion Akzo Co., Ltd.) 2w based on the solid content of silicone resin (SR2411: manufactured by Toray Dow Corning Silicone Co., Ltd.)
t% was dispersed for 10 minutes using a ball mill, and this dispersion was diluted to a solid content of 10 wt% to obtain a dispersion.

For 5 kg of the above ferrite core material 1,
Using a fluidized bed type coating device,
Coating at a rate of about 50 g / min in an atmosphere of 00 ° C., and further heating at 200 ° C. for 2 hours to give a film thickness of 0.5 μm.
The carrier A was obtained. The film thickness was adjusted by the amount of coating liquid. The volume resistivity of this carrier is 4.3 × 10 ^10.
It was Ωcm.

Here, the carrier resistance was obtained by filling a core material in a container having electrodes arranged in parallel at an interval of 2 mm, and measuring the direct current resistance between the two electrodes at 500 V by the Yokogawa Hewlett Packard 4329A High Resistance.
It was measured with Meter.

Production Example of Carrier B Carrier B was obtained in the same manner as carrier A except that ferrite core material 3 was used as the carrier core material.

Production Example of Carriers C to E Carbon (Ketjenblack EC-DJ600, manufactured by Lion Akzo Co., Ltd.) 2w based on solid content of silicone resin (SR2411: manufactured by Toray Dow Corning Silicone Co., Ltd.)
t%, and 0.7 parts of the aminosilane coupling agent having the following structure was dispersed for 10 minutes using a ball mill, and this dispersion was diluted to a solid content of 10 wt% to obtain a dispersion.

[Chemical 5]

5 of each of the above ferrite core materials 2 to 4
The above dispersion liquid was applied to kg at a rate of about 50 g / min in a 100 ° C. atmosphere using a fluidized bed coating apparatus, and further heated at 250 ° C. for 2 hours to give a film thickness of 0.5 μm. Carriers C to E were obtained. The film thickness was adjusted by the amount of coating liquid. The volume resistivity of this carrier was 5.7 × 10 ¹⁰ Ωcm.

Production Example of Carrier F In the production examples of Carriers C to E, the addition amount of carbon was 8 wt% and the addition amount of aminosilane coupling agent was 10%.
In the same manner, a dispersion liquid is prepared in an amount of wt%, and the dispersion liquid is applied to the ferrite core material 3 to form a carrier F having a film thickness of 0.5 μm.
Got The volume resistivity of this carrier is 5.7 × 10 ^7.
It was Ωcm.

Reference Example 2 (Production Example of Toners A and B) (Production Example of Toner A1) The following prescription was used for the production of Toner A1. Binder resin Polyester resin ・ ・ ・ 93 parts Release agent Carnauba wax No. 1 product ・ ・ ・ 5 parts Charge control agent Quaternary ammonium-containing styrene / acrylic copolymer ・ ・ ・ 2 parts

The above substances were thoroughly mixed in a blender, melted and kneaded in a twin-screw extruder, allowed to cool, coarsely pulverized in a cutter mill, then finely pulverized in a jet air stream type fine pulverizer, and then winded. Toner mother particles having a weight average particle diameter of 8.5 μm were obtained with a classifier. Hydrophobic silica fine powder R972 manufactured by Nippon Aerosil Co., Ltd. for 100 parts of the toner mother particles
Add 0.7 parts, mix with a mixer, open 100
Sieve with a micron sieve to remove coarse particles to obtain toner A1.

(Production Example of Toners A2 and A3) Toner A
The toner is kneaded in the same manner as in Production Example 1, and the conditions of pulverization and air classification are changed to obtain a weight average diameter of 7.1 μm and 9.2.
Toner mother particles of μm were obtained. Additives were mixed in the same manner as in Toner A1 to obtain Toners A2 and A3.

(Production Example of Toner B1) The following prescription was used for the production of Toner B1. Binder resin Polyester resin: 91 parts Coloring agent: Quinacridone magenta pigment (CI Pigment Red 122): 2 parts Release agent: Carnauba wax No. 1 product: 5 parts Charge control agent: Salicylic acid Derivative zinc salt: 2 parts

The above substances were thoroughly mixed in a blender, melted and kneaded in a twin-screw extruder, allowed to cool, coarsely pulverized in a cutter mill, and then finely pulverized in a jet air stream fine pulverizer, and then winded. Using a classifier, toner base particles having a weight average particle size of 7.1 μm were obtained. Hydrophobic silica fine powder R972 manufactured by Nippon Aerosil Co., Ltd. for 100 parts of the toner mother particles
Add 0.8 parts, mix with a mixer, open 100
Sieve with a micron sieve to remove coarse particles to obtain toner B1.

(Production Example of Toners B2 to B4) Toner B1
In the same manner as in the production example, the materials are melt-kneaded, allowed to cool, coarsely pulverized with a cutter mill, then finely pulverized by changing the air flow conditions with a jet air stream type fine pulverizer, and further weight average particle diameter 6 with a wind classifier. Toner base particles having a particle size of 0.8 μm, 5.1 μm and 3.2 μm were obtained. Hydrophobic silica fine powder manufactured by Nippon Aerosil Co., Ltd. for 100 parts of toner mother particles of each particle size
R972 was added at 0.8 parts, 1.0 parts and 1.2 parts respectively, mixed with a mixer, and sieved with a sieve having an opening of 100 μm to remove coarse particles to obtain toners B2 to B4.

Example 1 A copying machine imagio 6550 manufactured by Ricoh was modified, and two small two-component developing units having a sleeve diameter of 16 mm were attached to the developing section. The developing device on the charging device side (upstream side in the moving direction of the photosensitive member) of the photoconductor is D1, the downstream side is D2,
The developing gap was 0.4 mm, respectively. 93 parts of carrier A prepared as described above for D1 and toner A1 7
A developer consisting of 10 parts of the carrier C prepared as described above and a developer consisting of 10 parts of the toner B1 were added to D2, and an image was output as follows, and the output image was evaluated.
At this time, the potential of the image portion on the photoconductor (V _L ) = about −200
V, non-image portion potential (V _D ) = about −600 V, and developing sleeve applied voltage (V _B ) = about −450 V were used for image formation.
Image evaluation was performed as follows. The evaluation results are shown in Table 1 below. Although the toner uses magenta color, the present invention is not limited to magenta color.

Fine line reproducibility 600 dot / inch (about 2.5
4 cm), a 150-line / inch 1-dot lattice line image was output, and breaks and blurring of the line image were observed with a microscope and evaluated in the following four stages. ◎: Very good, ○: Good, △: Slightly bad, ×: Bad (x
Is an unacceptable level)

Resolving power 600 dot / inch, 150 l for both main scanning and sub-scanning
1 dot independent of ine / inch, output halftone dot image,
Dot omission, dot density unevenness, and dot shape variation were observed with a microscope and visually evaluated in four levels. ◎: Very good, ○: Good, △: Slightly bad, ×: Bad (x
Is an unacceptable level)

Halftone uniformity 600 dot / inch, 150 l for both main scanning and sub-scanning
A halftone dot image of 16 gradations of ine / inch was output, and the uniformity of each density was visually evaluated in four levels. ◎: Very good, ○: Good, △: Slightly bad, ×: Bad (x
Is an unacceptable level)

A character image chart of carrier adhesion and a vertical line image in which 2, 4, 6-dot lines are repeated at a 4-dot width interval are output, and the presence or absence of carrier adhesion around the character portion and on the white background between the vertical lines is visually determined. did. ◎: Very good, ○: Good, △: Slightly bad, ×: Bad (x
Is an unacceptable level)

Examples 2 to 9 In Examples 2 to 9, images were output in the same manner as in Example 1 except that the combinations of the carrier and the toner were changed to those shown in Table 1, and the obtained images were evaluated. I went. Table 1 shows combinations of carriers and toners and evaluation results.

Comparative Example 1 In Example 1, 90 parts of carrier A and toner A1
Using a developer obtained by mixing 5 parts of toner B2 and 5 parts of toner B2, an image was obtained and evaluated under the same developing conditions as in Example 1. The evaluation results are shown in Table 1 below.

[0071]

[Table 1]

[0072]

As described above, according to the present invention, by developing the non-image area and the image area with different developers using two developing units, it is possible to output a high-definition image which has never been seen before. However, it is possible to provide a developing method and a developer capable of developing without causing carrier adhesion.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an example of an image forming apparatus using an electrostatic latent image developing method of the present invention.

[Explanation of symbols]

D1, D2 development unit G1 charging unit P1 latent image carrier Pa Transferee T1, T2 toner Tr1 transfer device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/01 G03G 9/08 361 113 9/10 352 15/08 507 15/08 507L (72) Inventor Naoki Imahashi 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd. (72) Inventor Hiroaki Takahashi 1-3-3 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H005 AA21 AA29 BA02 BA06 BA07 CA12 CA18 CA21 CB04 EA01 EA05 EA10 FA02 2H027 EA04 EB06 ED06 ED07 ED08 FA28 2H077 AD02 AD06 AD36 AE06 BA10 EA03 GA12 GA17 2H171 FA13 FA14 UA21 FA25 UA26 UA26 QBWABWAB QB33 QB53 QB53 QB33 QB53 QB33 QB53 QB33 QB53 QB33 QB53 QB53 QB53 QB33 QB53 QB53 QB33 QB53 QB53 QB53 QB33 QB53 QB33 QB53 QB53 QB53 QB33 QB53 QB33 QB53 QB33 QB53 2H300 EB12 EJ09 EJ12 EJ27 EJ30 EJ33 EJ35 EJ45 EJ49 EJ50 EJ52 EJ56 FF20 GG01 GG02 GG13 GG14 KK02 KK03 KK06 KK08 KK12 KK13 KK16 KK17 MM03 MM11 MM12 MM13 MM25 NN04 PP02 PP03 RR49

Claims (9)

[Claims] 1. A charging means for charging at least one electrostatic latent image carrier, a developer comprising a carrier having magnetism to the electrostatic latent image carrier and a non-magnetic toner. The surface of the electrostatic latent image bearing member and the surface of the developer bearing member are moved in parallel with each other so that the surface of the developing agent carrier to be carried is relatively moved at a different speed between the surface of the developing agent carrier and the surface of the electrostatic latent image bearing member. A developing unit for developing the toner on the electrostatic latent image carrier by forming an electric field between the two, and a transfer unit for transferring the toner image developed on the electrostatic latent image carrier to the transfer target member. The developing method used is a charging means, a developing means D1, a developing means D2, and a transferring means provided in this order from the upstream side with respect to the moving direction of the electrostatic latent image carrier, and the developing means D1 contains a colorant. Develop the non-image area with toner T1 that does not And toner T containing a colorant
2. An electrostatic latent image developing method, characterized in that the image portion is developed with 2. 2. The developing method according to claim 1, wherein the developer used in the developing means D2 has a weight average particle diameter of at least 10.
Carrier containing a magnetic substance of ˜25 μm and the toner T
2. An electrostatic latent image developing method, which is a developer consisting of 2. 3. The developing method according to claim 1, wherein the toner T1 and the toner T2 have different charge amounts, and the charging polarity of the toner T2 is the same as the charging polarity of the electrostatic latent image carrier. And a method for developing an electrostatic latent image. 4. The electrostatic latent image developing method according to any one of claims 1 to 3, wherein the carrier of the developing means D1 has a weight average particle diameter of 35 μm or more. 5. The developing method according to claim 1, wherein the developer contained in the developing means D2 has a toner coverage of 25 to 50% on the carrier. Electrostatic latent image developing method. 6. The electrostatic latent image developing method according to claim 1, wherein the carrier has a direct current resistance of 1 × 10 ⁸ Ωcm or more. 7. The electrostatic latent image developing method according to any one of claims 1 to 6, wherein the carrier is coated with a silicone polymer having Si—O as a main repeating unit. 8. The developing method according to claim 1, wherein the toner T2 included in the developing means D2 contains a colorant selected from yellow, magenta, cyan, and black. And an electrostatic latent image developing method. 9. A magnetic material having a true specific gravity of 2.5 to 6 g / cm.
³ , a substantially spherical carrier having a weight average particle diameter of 10 to 25 μm, and a coloring agent selected from yellow, magenta, cyan and black, and the weight average particle diameter of the coloring agent is the weight of the carrier. An electrostatic latent image developer having an average diameter of 1/2 to 1/10.