JPH06324514A - Electrostatic charge image developing method - Google Patents

Abstract

PURPOSE:To provide the electrostatic charge image developing method applying a good fixing/mold releasing property capable of obtaining an image excellent in stability with the lapse of time, capable of preventing the toner filming (fusion) to a developer carrier, and applying a good fixing/mold releasing property. CONSTITUTION:Toner grains 60 are carried on a developer carrier, the toner grains 60 are brought into contact or no contact with an electrostatic latent image holding body 10 constituted of an organic photoreceptor facing the developer carrier to develop a latent image in this method, and the surface of the developer carrier is made of at least a resin layer. The toner grains 60 are mainly made of a binding resin, a colorant, a charge control agent, and a mold releasing agent. The difference between the solubility parameter values (SP values) of the resin of the resin layer on the surface of the developer carrier and the binding resin of the toner grains 60 is set to 1.5Cal<1/2>.cm<-2/3>, and the mold releasing agent used for the toner grains 60 is made of one or a combination of two of (a): desorption fatty acid type carnauba wax, (b): montan ester wax, and (c): rice oxide wax having the acid value of 10-30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method and a toner for developing an electric latent image in electrophotography, electrostatic printing and the like.

[0002]

2. Description of the Related Art Generally, in an electrophotographic method or an electrostatic recording method, a developing sleeve is used for developing an electrostatic latent image formed on a latent image carrier made of a photoconductive photoreceptor or a dielectric. After the toner image is transferred to a transfer material such as paper after development using a toner that has been thinned by a blade or the like on a toner supply roller, and is appropriately charged into a fine powder, heating pressure, It is fixed by solvent vapor or the like to obtain a copy.

The developing methods applied to these electrophotographic methods and the like are roughly classified into a dry developing method and a wet developing method. The former is further divided into a method using a two-component developer and a method using a one-component developer. Among the two-component developing methods, there are a magnet brush method using an iron powder carrier, a cascade method using a bead carrier, a fur brush method using a fur, etc., depending on the type of carrier that carries the toner.

Further, among the one-component developing methods,
Powder cloud method in which toner particles are sprayed, contact development method in which toner particles are brought into direct contact with the electrostatic latent image surface to develop (contact development or toner development), toner particles are directly applied to the electrostatic latent image surface Jumping developing method in which toner particles are charged and fly toward the latent image surface by the electric field of the electrostatic latent image without contact, magnetic conductive toner is brought into contact with the electrostatic latent image surface to develop it. There are laws etc.

In these developing methods, in order to improve the offset property at the fixing portion, silicone oil or the like is used as a release agent, or low molecular weight polyethylene or polypropylene is given to the toner to provide releasability. It is mixed with. In this case, low-molecular-weight polyethylene or polypropylene has poor compatibility with polystyrene used as a binder resin, and therefore phase separation occurs during kneading. At the interface due to phase separation, destruction is easily caused by the application of mechanical force, and there is a phenomenon that the toner is pulverized. For example, toner pulverization occurs at the contact surface between the photoconductive photoreceptor and the paper, at the contact surface between the developing sleeve and the blade, and at the contact surface between the developing sleeve and the photoconductive photoreceptor. .

In the case of the contact developing method, for example, the finely divided toner adheres to the developing sleeve to cause a fusing phenomenon over time and filming on the developing sleeve. When the filming phenomenon appears on the developing sleeve, the thickness of the laminated toner layers becomes non-uniform, which causes a non-uniform distribution of the charge amount during the development of the electrostatic latent image, which is caused by the developing sleeve. This causes non-uniformity of the toner adhesion amount per unit area, and as a result, light and shade also occur on the copy, which causes a serious problem on the image. The pulverization of the toner caused by the knotting of the toner particles means that the toner is easily pulverized by a mechanical force, which is preferable from the viewpoint of toner productivity. Therefore, in order to avoid such a filming phenomenon, it is possible to use a high molecular weight polymer. However, considering the heat fixing of an image that is usually performed in the final step of copying or printing, the fixing temperature rises and the fixing In this case, a large amount of heat is required, which is not preferable from the viewpoint of energy saving or downsizing of hardware equipment. Further, in order to eliminate this phenomenon, it has been proposed to add a small amount of a plasticizer to the toner, but there are problems such as impairing the free flowability of the toner and contaminating the carrier, etc. Not successful. On the other hand, if the toner is too hard, it becomes impossible to mechanically pulverize it, or the toner cannot be sufficiently dispersed by kneading.

For the above reasons, relatively low molecular weight polystyrene or styrene-butyl methacrylate copolymer having a suitable hardness has been used as a binder resin for toner. However, in the case of equipment that has an electrophotographic system such as a laser printer and is desired to be maintenance-free, in a general melt-kneading using a polymer such as styrene-butyl methacrylate copolymer that has been conventionally used, The kneading state of the main polymer and low-molecular-weight polyethylene added to have releasability is not appropriate, and phase separation forms a large domain structure in the macroscopic region of micron order. Therefore, it has been found that the separation at the interface in the phase separation easily occurs, the hardness when used as a toner is not sufficient, and a toner that forms a higher-order structure having higher mechanical strength is required. Also, from the viewpoint of maintenance-free,
The developing process is considered to be preferable to the one-component developing method, which makes the system simpler than the two-component developing method using a carrier or the like. Further, this type of binder resin has insufficient characteristics in heat fixing using a heat roll which is currently widely used, and the toner binder resin is not melted by heat and adhered well to paper or the like. However, there is an offset phenomenon on the heat roller.

Further, a fluidization accelerator is often used in order to suppress filming on the developing roller or the photosensitive member and spent on the carrier. For example, JP-A-47-3
6405 and Japanese Patent Laid-Open No. 47-36830 disclose the use of metal soaps, Japanese Patent Laid-Open Nos. 52-153441 and 53.
No. 147541 discloses the use of a fluorine-based compound, JP-A No. 54-8534 discloses the use of a nonionic surfactant, and JP-A No. 56-62256 discloses the use of silica having a hydrophobic surface. , Each have been proposed.

Further, in Japanese Patent Laid-Open No. 56-66856, it is possible to bury particles harder than the toner on the toner surface.
In JP-A-58-134651, it is disclosed in JP-A-59-1319 that the binder resin contains an ion exchange resin.
According to Japanese Patent Laid-Open No. 43-197348, silicone oil is contained in the binder resin in order to exhibit a mold releasing effect while being compatible with the binder resin by using oxidized polyethylene as a releasing agent. In JP-A-59-220748, wax particles are externally added to the toner, and in JP-A-60-138565, carbon black is externally added to reduce the resistance of the toner. JP-A-60-186851, JP-A-60
-186852, JP-A-60-186853, JP-A-60-186854, JP-A-60-186855.
No. 60-186857 and 60-186.
858, JP-A-60-186860, JP-A-60-
186861, JP-A-60-188682, JP-A-60-186863, JP-A-60-186864,
JP-A-60-186865, JP-A-60-18686
No. 6, the fine polymer particles are externally added, and in Japanese Patent Laid-Open No. 61-99164, an abrasive (SiC,
It has been proposed to externally add (SiN). However, the effect of suppressing the toner fusion (filming) to the developing roller is still insufficient only by using the additive as described above.

[0010]

SUMMARY OF THE INVENTION The present invention is capable of achieving high image quality and stability over time in a one-component developing method that does not use a carrier, and at the same time prevents the toner from being fused to the developing roller. Another object of the present invention is to provide an electrostatic charge developing method having excellent offset resistance suitable for a heat roller fixing method in which oil is not applied.

[0011]

According to the present invention, a toner is carried on a developer carrying member, and the toner is brought into contact with an electrostatic latent image holding member composed of an organic photoconductor facing the developer carrying member. Alternatively, in the method of developing a latent image in a non-contact manner, the surface of the developer carrying member is composed of at least a resin layer, and the toner contains a binder resin, a colorant, a charge control agent and a release agent as main components, The difference between the solubility parameter value (SP value) of the resin of the resin layer on the surface of the developer carrier and the binder resin of the toner is the following value (Equation 1) or more,

[Equation 1] Further, there is provided an electrostatic charge image developing method characterized in that the release agent used in the toner comprises one or a combination of two shown below. <Release Agent> (a) Free fatty acid type carnauba wax having an acid value of 5 or less (b) montan ester wax (c) oxidized rice wax having an acid value of 10 to 30 Further, the binder resin contained in the toner is When there are two or more types, the SP value of each resin (A, B ... N) is SP-A, SP
-B, ... SP-N, and the content of each resin with respect to the total resin is A / 100, B / 100, ... N / 100 (A + B + ... N = 100), the following value (Equation 2)

[Equation 2] The difference in the SP value of the resin on the surface of the developer carrier is the following value (Equation 1)

[Equation 1] An electrostatic charge image developing method characterized by the above is provided.

The present inventors carry toner on a developer carrying member having a surface layer of at least a resin layer, and contact the toner with a latent image holding member made of an organic photoconductor facing the developer carrying member. In the method of developing a latent image in a non-contact manner, when a toner containing a release agent is used, the difference between the SP value of the resin on the surface layer of the developer carrier and the SP value of the binder resin contained in the toner Was more than a certain value, and it was effective to use a certain type of release agent.

The solubility parameter (SP value) of the resin is
Those having similar values are likely to be compatible with each other, and it is presumed that this effect is related to the fusing (filming) characteristics of the binder resin in the toner to the resin on the surface layer of the developing roller. That is, when the difference in SP value between both resins is small, the toner tends to be easily fused to the resin on the surface layer of the developing roller. The solubility parameter SP value (δ) in the present invention is defined by the following equation as a function of cohesive energy density. δ = (△ E / V) 1/2 (1) △ E: Intermolecular cohesive energy (heat of evaporation) V: Total volume of mixed solution △ E / V: Cohesive energy density Also, using SP value , Hm change due to mixing is expressed by the following formula. ΔHm = V (δ ₁ −δ ₂ ) Φ ₁ Φ ₂ (2) δ ₁ : SP value of solvent δ ₂ : SP value of solute Φ ₁ : Volume fraction of solvent Φ ₂ : Solute Volume fraction From this equation, the closer the values of δ ₁ and δ ₂ are, the smaller ΔHm is, and the smaller the Gibbs free energy is.
Those having a small difference in P value are considered to have high affinity. As a method for actually determining the SP value, by comparing the solubility of the resin with various solvents having known SP values,
The SP value of the unknown resin was set from the SP value of the solvent that was most compatible.

Further, the developer carrying member has a function of imparting an appropriate charge to the toner and a function of transporting the thinned toner, and in order to appropriately maintain these functions, the two-component developer is used. Similar to coating various resins on the surface of the carrier, it is preferable to form at least the resin layer on the surface of the carrier, and the difference between the SP value of this resin and the SP value of the binder resin in the toner should be a constant value. As described above, it is necessary for the present invention to have the above.

The resin used for the surface layer of the developer carrying member of the present invention should be selected in consideration of the difference in the SP value of the binder resin in the toner, but the relationship of the SP value is satisfied. As far as possible, the following items are selected.
Silicone resins, various modified silicone resins, Teflon-based resins, epoxy resins, etc. may be mentioned. If necessary, various conductive powders (carbon black, various metal particles, etc.) may be added to these to carry a developer carrier. It is possible to adjust the electric resistance of the surface layer. This makes it possible to improve the rise of the charge amount of the toner layer, and to alleviate the edge enhancement effect of the image during development.

Next, the toner of the present invention will be described.
The binder resin contained in the toner of the present invention is selected in consideration of the SP value of the resin used for the surface layer of the developer carrier, but the resin on the surface of the developer carrier corresponding to the scope of the present invention. Any binder resin can be used as long as it satisfies the relationship with the SP value of styrene and homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and substitution products thereof. : Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer Coal, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, Tylene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether Ter copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Styrenic copolymers such as copolymers; polymethylmethacrylate, polybutylmethacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide,
Epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, etc. are used while considering the fixing characteristics and developing characteristics. be able to.

Further, for the purpose of imparting releasability to the toner,
Although various release agents have been tried to be added, in order to achieve the object of the present invention, the above-mentioned release agent is (a) a free fatty acid type carnauba wax having an acid value of 5 or less. ) Montane ester wax (c) It is necessary to use at least one kind of oxidized rice wax having an acid value of 10 to 30.

The free fatty acid type carnauba wax having an acid value of 5 or less in (a) is obtained by removing free fatty acids from carnauba wax as a raw material, and therefore has an acid value of 5 or less. It is finer crystal than the conventional carnauba wax, and the dispersed particle diameter in the binder resin is 1 μm or less, and the dispersibility is dramatically improved.

The montan ester wax (b) is
It is purified from minerals, becomes fine crystals like carnauba wax, and has a dispersed particle diameter of 1 μm or less in a binder resin, thus improving dispersibility. In the case of montan ester wax, the acid value is especially 5
It is preferably 14.

The oxidized rice wax (c) is obtained by air-oxidizing rice bran wax and has an acid value of 10
~ 30. When the acid value is less than 10, the lower limit fixing temperature rises and the low temperature fixability becomes insufficient, and when it is more than 30, the cold offset temperature rises and the low temperature fixability also becomes insufficient.

The above waxes may be used alone or in combination, and they may be used in an amount of 1 to 15% by weight of the total toner.
Preferably, the content of 2 to 10% by weight provides the above-mentioned good results. These release agents have good dispersibility in the binder resin, and there is no elution or desorption of the release agent from the toner surface, and toner fusion (filming) on the surface of the developer carrier. And prevent the toner from being fixed (offset resistance).

The charge control agent contained in the toner according to the present invention is one that controls the toner to have a positive charging property.
The quaternary ammonium salt and other organic substances having a basic electron donating property such as a metal complex of a monoazo dye and a tetraphenylboron derivative such as tetraphenylboron sodium and potassium are mentioned as those which are controlled to be negatively charged. . The amount contained in the toner is 1 to 10% by weight based on the total amount of the binder resin.

As the additive to be contained in the toner according to the present invention, a fluidity-imparting agent such as colloidal silica or aluminum oxide is indispensable, but in addition, an anti-caking agent or a conductive material such as carbon black or tin oxide. A property imparting agent or a fixing aid such as a low molecular weight polyolefin may be added. Further, as a lubricant for preventing sticking of the blade in the developing section, a fatty acid metal salt, for example, barium stearate, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, lithium stearate, lead stearate,
You may add barium laurate, calcium laurate, zinc laurate, magnesium laurate, lithium laurate, lead laurate, calcium palmitate, magnesium palmitate, dibasic lead stearate and the like. The amount of these fatty acid metal salts added is preferably 0.01 to 5% by weight with respect to the total amount of the toner.

The electrostatic charge image developing method will be described below. FIG. 1 shows an outline centering on a developer carrier portion of a typical developing device useful for carrying out this developing method. Figure 1
In the toner tank 70, the toner 6
0 is a toner supply member (such as a sponge roller or a fur brush) by a stirring blade (toner supply auxiliary member) 50.
The toner 60 is forcibly moved to 0, and the toner 60
Supplied to zero. On the other hand, the developer carrying member (developing roller) 20 that has completed development rotates in the direction of the arrow (for example, 40
0 rpm) to reach the contact portion with the toner supply member 40.
The toner supply member 40 rotates in the direction opposite to the direction of the developer carrier 20, charges the developer carrier 20 and the toner 60, and attaches the toner 60 to the developer carrier 20. Further, the developer carrying member 20 rotates, and the toner adhered on the developer carrying member 20 is removed by the toner layer thickness regulating member (elastic blade) 30.
The charge is stabilized while the thickness is controlled, and the developing area 80
Reach In the development area 80, the latent image is developed by contact or non-contact development. Here, if necessary, a bias voltage such as direct current, alternating current, direct current superimposed alternating current, or pulse is applied to the developer carrying member 20 and the toner supply member 40,
The optimal image can be controlled.

Next, the mechanism of toner adhesion to the developer carrier 20 of this type (electrode type) will be described. As an example of the developer carrier 20, as shown in FIG. 2, for example, a dielectric portion and a conductor portion are formed on the surface so as to be mixed in a minute area. The size of the area is
If the shape is circular, the diameter is 30 ~ 2000μ
m, preferably 100 to 400 μm in size, are dispersed randomly or according to a certain rule.
The area ratio is preferably such that the area of the dielectric portion is 50 to 80%.

Toner adhesion is as follows. First, the developer carrying member 20 that has completed development rotates in the direction of the arrow and contacts the toner supply member 40. The residual toner in the non-developed portion that has not been developed here is mechanically and electrically scraped by the toner supply member 40, and the dielectric portion is charged by friction. At this time, the charges of the developer carrying member 20 and the toner due to the previous development are fixed and initialized by friction. Next, the toner carried by the supply member 40 is charged by friction and electrostatically adheres to the dielectric portion of the developer carrying member 20. At this time, the polarity of the toner is opposite to that of the charge on the photoreceptor, and the dielectric portion of the developer carrying member 20 has the same polarity. The electric field on the developer carrying member 20 at this time becomes a microfield (closed electric field) as shown in FIG.
The electric field has a large electric field gradient, and the toner can be attached in multiple layers. Further, since the adhered toner has a closed electric field, it is strongly attracted to the developer carrier 20 side,
It becomes difficult to separate.

The toner layer thickness of the toner layer is further controlled by the toner layer thickness regulating member 30 and reaches the developing area 80. The electric field between the developer carrier 20 and the electrostatic latent image carrier (photoconductor) 10 in the developing area 80 has a large electrode effect,
The toner on the developer carrying member 20 becomes an electric field that is easily attached to the electrostatic latent image carrying member 10, and development is performed.

[0028]

EXAMPLES The present invention will be described below based on examples. The SP value is abbreviated in its unit (Equation 3).

[Equation 3] Example 1 The following toner was used for the developing unit shown in FIG. 1 in which the dielectric portion of the developing roller (developer carrying member) of the developing unit was a silicone resin (SP value: 7.3). [Toner formulation] Polyester resin (SP value: 9.5) 100 parts by weight Free fatty acid type carnauba wax (acid value: 3) 5 parts by weight Carbon black 10 parts by weight Chromium-containing azo dye 3 parts by weight The above substances are blended. After thoroughly mixing, 120-1
Melt-kneading was performed with a two-roll roller heated to 40 ° C. After allowing the kneaded product to cool naturally, roughly crushed with a cutter mill, after pulverization with a fine crusher using a jet stream, using an air classifier,
The volume average particle diameter was set to 8 μm to obtain a base toner. Furthermore,
To this, hydrophobic silica fine powder was mixed in a mixer at a ratio of 0.5 parts by weight to 100 parts by weight of the base oner to obtain a toner. Next, a Ricoh laser printer (PC-6
000) was modified, the developing unit was mounted, and the toner was put in the developing unit to evaluate the image. As a result, the image density by the initial Macbeth densitometer (manufactured by Macbeth Co.) was 1.35, and the image density after 20,000 continuous prints was 1.32. Further, toner filming (fusing) to the developing roller did not occur, and the fixing releasability was also good.

Example 2 The following toner was used for the developing unit shown in FIG. 1 in which the dielectric portion of the developing roller (developer carrying member) of the developing unit was Teflon resin (SP value: 6.2). [Toner formulation] Styrene-butyl acrylate copolymer (SP value: 9.0) 100 parts by weight Montane ester wax 5 parts by weight Copper phthalocyanine blue pigment 2 parts by weight Salicylic acid derivative Zn salt 3 parts by weight Toner was prepared in the same manner. Next, a Ricoh laser printer (PC-600
No. 0) was modified, the developing unit was attached, and the toner was put in the developing unit to evaluate the image. As a result, the initial image density was 1.30, and the image density after 20,000 continuous prints was 1.31. Further, toner filming (fusion) on the developing roller did not occur and the fixing releasability was good.

Example 3 An epoxy-modified silicone resin (SP value: 7.9) was used as Al.
A developing roller (developer carrying member) having a surface of a cored bar coated with about 30 μm was prepared, and this was mounted on the developing unit shown in FIG. 1 and the following toner was used. [Toner formulation] Polyester resin (SP value: 9.5) 50 parts by weight Styrene-n-butyl m-acrylate copolymer (SP value: 9.3) 50 parts by weight Quinacridone red pigment 4 parts by weight Oxidized rice wax (acid value 15) 5 parts by weight Salicylic acid derivative Zn salt 3 parts by weight The above substances were prepared in the same manner as in Example 1 to obtain a toner. Next, a Ricoh laser printer (PC-600
No. 0) was remodeled, the developing unit was attached, the toner was added, and the image was evaluated in the same manner as in Example 1. As a result, the initial image density was 1.33, and continuous printing 2
The image density after 10,000 sheets was 1.40. Also, toner filming (fusion) on the developing roller has not occurred,
The fixing releasability was also good.

Example 4 Image evaluation was performed in the same manner as in Example 1 by using a developing unit equipped with the same developing roller (developer carrying member) as in Example 1 and the following toner. [Toner formulation] Styrene-n-butyl m-acrylate copolymer (SP value: 9.3) 50 parts by weight Styrene-butyl acrylate copolymer (SP value: 9.0) 50 parts by weight Carbon black 10 parts by weight Free fatty acids Carnauba wax (acid value 4.5) 5 parts by weight Chromium-containing azo dye 3 parts by weight As a result, the initial image density was 1.35, continuous printing 2
The image density after 10,000 sheets was 1.32. Also, toner filming (fusion) on the developing roller has not occurred,
The fixing releasability was also good.

Example 5 Image evaluation was carried out in the same manner as in Example 1 using the same developing roller (developer carrying member) as in Example 2 and the following toner. [Toner formulation] Polyester resin (SP value: 9.5) 50 parts by weight Epoxy resin (SP value: 10.2) 50 parts by weight Carbon black 10 parts by weight Montane ester wax 5 parts by weight Chromium azo dye 3 parts by weight As a result, the initial image density is 1.31 and continuous printing is 2
The image density after printing 10,000 sheets was 1.34. Also, toner filming (fusion) on the developing roller has not occurred,
The fixing releasability was also good.

Comparative Example 1 The following toner was used for the developing unit shown in FIG. 1 in which the dielectric portion of the developing roller (developer carrying member) was epoxy resin (SP value: 9.9). [Toner formulation] Polyethylene resin (SP value: 9.3) 50 parts by weight Polyester resin (SP value: 9.5) 50 parts by weight Free fatty acid-type carnauba wax (acid value: 3) 5 parts by weight Carbon black 10 parts by weight Parts Chromium-containing azo dye 3 parts by weight The above substances were prepared in the same manner as in Example 1 to obtain a toner. Next, Ricoh laser printer (PC-6000 machine)
Was modified, the developing unit was attached, and the toner was put in the developing unit, and image evaluation was performed in the same manner as in Example 1. As a result, a good image was obtained with an initial image density of 1.30, but as printing was overlaid, the toner filmed (fused) on the developing roller, and the image density after printing 20,000 sheets was 0.58. Fell to.

Comparative Example 2 The toner prepared in Example 5 was put into the developing unit and the evaluation device used in Comparative Example 1 and evaluated in the same manner as in Example 1. The initial image density was as good as 1.32. Although an image was obtained, as the prints were piled up, the toner filmed (fused) on the developing roller, and the image density after printing 20,000 sheets decreased to 0.66.

Comparative Example 3 The toner used in Example 3 was applied to a developing unit in which the dielectric portion of the developing roller (developer carrying member) of the developing unit shown in FIG. 1 was made of urethane resin (SP value: 10.0). When the same evaluation as in Example 1 was performed, a good image was obtained with an initial image density of 1.31, but as the prints were piled up, the toner filmed (fused) on the developing roller. The image density after printing 20,000 sheets decreased to 0.74.

Comparative Example 4 The toner prepared in Example 4 was placed in the developing unit and the evaluation apparatus used in Example 3 and evaluated in the same manner as in Example 1. The initial image density was 1.31 and was good. An image was obtained, but as the prints were piled up, the toner filmed (fused) on the developing roller, and the image density after printing 20,000 sheets dropped to 0.82.

Comparative Example 5 The same toner evaluation as in Example 1 was performed on the developing unit and the evaluation device used in Example 1 using the following toners. [Toner formulation] Styrene-n-butyl methacrylate copolymer (SP value: 9.3) 50 parts by weight Styrene-butyl acrylate copolymer (SP value: 9.0) 50 parts by weight Low molecular weight polypropylene 5 parts by weight Carbon Black 10 parts by weight Chromium-containing azo dye 3 parts by weight As a result, a good image with an image density of 1.35 was initially obtained, but as the prints were overlaid, the toner filmed (fused) on the developing roller, and 2 The image density after printing ten thousand sheets fell to 0.65. Further, a so-called offset phenomenon occurred in which toner adhered to the fixing roller during the continuous printing and the toner was retransferred to the image.

[0038]

According to the method of the present invention, a toner having a difference in solubility parameter between the resin on the surface of the developer bearing member and the binder resin in the toner is not less than a certain value, and the toner contains a specific release agent. Therefore, an image excellent in stability over time can be obtained, and toner film (fusion) on the developer carrying member can be obtained.
Can be prevented, and good fixing releasability is imparted to the toner.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view centering on a developer carrier part showing an example of a developing device for forming a microfield electric field on a developer carrier useful for carrying out the present invention.

FIG. 2 is a schematic cross-sectional view for explaining a state in which a closed electric field due to a microfield is generated on a developer carrier in the apparatus shown in FIG.

3 (a) to 3 (c) are schematic cross-sectional views showing a surface state in a manufacturing process of a developer carrier used in the developing device of the type shown in FIG.

[Explanation of symbols]

 10 Electrostatic Latent Image Carrier 20 Toner Conveying Member 30 Toner Layer Thickness Controlling Member 40 Toner Supplying Member 50 Stirring Blade 60 Toner 70 Toner Tank 80 Development Area

Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location G03G 13/08 8004-2H (72) Inventor Minoru Masuda 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company In Ricoh

Claims (2)

[Claims] 1. A method of carrying a toner on a developer carrying member, and developing the latent image by contacting or non-contacting the toner with an electrostatic latent image holding member made of an organic photoconductor facing the developer carrying member. In the above, the surface of the developer carrying member is composed of at least a resin layer, and the toner contains a binder resin, a colorant, a charge control agent and a release agent as main components, and the resin of the resin layer on the surface of the developer carrying member. And the difference in the solubility parameter value (SP value) of the binder resin of the toner is not less than the following value (Equation 1), Further, the releasing agent used for the toner is composed of one kind or a combination of two kinds shown below, and an electrostatic image developing method. <Release Agent> (a) Free fatty acid type carnauba wax having an acid value of 5 or less (b) montan ester wax (c) oxidized rice wax having an acid value of 10 to 30 2. The binder resin contained in the toner is composed of at least two kinds of resins, and S of each resin (A, B ... N).
The P value is SP-A, SP-B, ... SP-N, and the content of each resin with respect to the total resin is A / 100, B / 10.
0, ... N / 100 (A + B + ... N = 10
0), the following value (Equation 2) and The difference in the SP value of the resin on the surface of the developer carrier is the following value (Equation 1) The above is the electrostatic charge image developing method characterized by the above.