JP3073782B2 - 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 a method of supplying a one-component developer to which an auxiliary agent is externally added as needed to a developer carrier which is driven to rotate, and developing the developer on the surface of the developer carrier. In the developing area where the latent image carrier and the developer carrier are opposed to each other, the electrostatic latent image formed on the latent image carrier is carried on the developer carrier. The present invention relates to an image forming method for making a visible image with a developer.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copier, a printer or a facsimile, which forms an electrostatic latent image on a latent image carrier and visualizes the latent image with a developer to obtain a recorded image, a powdery image is formed. Dry developing devices using a developer are widely used.

As such a powdery developer, a two-component developer having a toner and a carrier and a one-component developer not containing a carrier are known, and the former two-component developer is used. In the two-component developing method, a relatively stable and good recorded image can be obtained, but the deterioration of the carrier and the fluctuation of the mixing ratio of the toner and the carrier are apt to occur, the maintenance of the apparatus is complicated, and the structure of the entire apparatus is large. It has a disadvantage that it is easy to change.

[0004] From such a viewpoint, a one-component developing system using a one-component developer which does not have the above-mentioned disadvantages has attracted attention. One-component developer is composed of only toner,
In some cases, an auxiliary agent is externally added as necessary. As the toner, there are a magnetic toner in which magnetic powder is kneaded into each toner particle itself, and a non-magnetic toner containing no magnetic material. Here, since the magnetic material is generally opaque,
When a color image including a full-color image and a multi-color image is formed with a magnetic toner, a developed visible image becomes unclear and a vivid color image cannot be obtained. Therefore, it is desirable to adopt a one-component developing method using a non-magnetic toner especially for color development.

In a developing device employing a one-component developing system, a one-component developer is carried on a developer carrier and conveyed, and the developer carrier and the latent image carrier are opposed to each other. In the region, the electrostatic latent image formed on the latent image carrier is visualized with a developer, but in order to form a high-quality visible image of a predetermined density, a large amount of sufficiently charged toner is required. It is necessary to convey the latent image to a developing area and visualize the latent image with the toner.

In the case where a magnetic toner is used, the above-described requirement can be relatively easily satisfied because the one-component developer can be carried on the developer carrier by utilizing the magnetic force of a magnet provided in the developer carrier. It is possible to satisfy

However, when a non-magnetic one-component developer is used, it cannot be supported on a developer carrier by magnetic force, so that it is difficult to satisfy the above requirements. Various measures have been proposed for this,
For example, JP-A-61-42672 discloses that a layer of a dielectric (insulator) is formed on the surface of a developer carrying member (developing roller), and a developer supplying member comprising, for example, a sponge roller. Are pressed against each other to frictionally charge them with different polarities, and a non-magnetic toner charged with a polarity opposite to that of the dielectric is electrostatically attached to the dielectric, and the one-component developer is transported to the developing area. A way to do that has been proposed. However, even with this method, the strength of the electric field formed in the vicinity of the dielectric surface cannot be sufficiently increased, so that it is difficult to carry a large amount of toner on the surface of the developing roller, and the developing roller can be transported to the developing area. Insufficient amounts of the agent make it difficult to form a high-density visible image.

It is also known to apply an electric field between the developing roller and the developer supply member in such a direction that the non-magnetic toner electrostatically moves to the developing roller side. However, it is difficult to attach a sufficient amount of toner to the developing roller.

[0009] The toner supply member includes 10 ² to 10 ⁶
Ωcm conductive foam (JP-A-60-229057), elastic body with skin layer (JP-A-60-229060) and fur brush
(Japanese Patent Application Laid-Open No. 61-42672) and the like, and as a developing roller, a metal body having irregularities on its surface (Japanese Patent Application Laid-Open No. 60-53976), an insulating coated roller body ( JP-A-55-46768) Medium resistance coated roller (JP-A-58-132)
No. 768) and an electrode roller having an insulating surface and a conductive surface (JP-A-53-36245).

Further, in a developing apparatus using a non-magnetic one-component developer, a sponge roller is disclosed in JP-A-60-229057, an elastic roller is disclosed in JP-A-62-229060,
In 52663, using a fur brush or the like, a charge is applied to the toner by frictional charging between the toner and the replenishing member, and further, by friction in contact with the developing roller, the toner is electrostatically attached to the developing roller, Further, the latent image on the photoreceptor is developed by controlling the toner layer using a layer thickness regulating member such as a blade. As the material of the developing roller, various materials such as an insulating material, a medium-resistance material, and a laminated material are used.

According to the methods shown in these references, toner is adhered to the developing roller by friction between the toner replenishing member and the developing roller. Is difficult to obtain, resulting in insufficient toner adhesion. The need for a large amount of this adhesion also makes one-component development difficult.

Further, as shown in Japanese Patent Application Laid-Open No. 54-51841, the one-component developer on the developing roller after passing through the developing area is scraped off, and the surface layer of the developing roller is removed. On the other hand, there has been proposed a technique in which a corona discharge is performed to apply a charge, and then a non-magnetic toner is positively electrostatically adhered to a developing roller by a developer supply member. Also, the amount of developer carried on the surface of the developing roller cannot be increased, and a large amount of developer cannot be transported to the developing area.

As a method of solving these problems, the present inventors have previously described a one-component system comprising a non-magnetic toner in which an auxiliary agent is externally added to a rotatable developer carrier, if necessary. A developer is supplied, the developer is carried on the surface of the carrier and transported, and the latent image carrier and the developer carrier are formed on the latent image carrier in a developing region facing each other. In a developing method of visualizing an electrostatic latent image by the developer carried on a developer carrying member, the developing device selectively holds electric charges on the surface of the developer carrying member so as to be in the vicinity of the carrier carrying surface. An image in which a large number of minute closed electric fields are formed, charged toner is sucked by the closed electric field, and a developer is adhered to and carried on the surface of the developer carrier, and the electrostatic latent image is visualized by the carried developer. Method of formation "was proposed.

In this method, a large number of minute electric fields (microfields) are formed in the vicinity of the surface of the developer carrier, so that the intensity of the electric field can be significantly increased as compared with the conventional method, and a sufficiently charged large amount of electric fields can be obtained. This has many advantages such that the toner can be carried on the developer carrying member and transported to the developing area.

[0015]

However, according to the subsequent studies by the present inventors, according to the developing method in which a large number of minute closed electric fields (microfields) are formed near the surface of the developer carrier as described above. It is difficult to always stabilize the toner layer on the developer carrier as two or more layers, the toner layer becomes thinner, the amount of toner to be developed is reduced, and the density of the image portion is reduced, The toner layer becomes non-uniform and uneven development may occur, or fogging may occur.Furthermore, a filming phenomenon often occurs on the developer carrier, and the microfield effect is reduced. It has been found that the amount of toner held on the developer carrier decreases, and it becomes difficult to sufficiently develop the toner on the latent image carrier.

Accordingly, an object of the present invention is to provide a method for forming an image, comprising the steps of: stably and uniformly laminating two or more toner layers on a developer carrier; It is an object of the present invention to provide an image forming method in which the image formation is controlled so that high-density and high-quality images can be obtained over a long period of time.

[0017]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the use of a toner containing a binder resin and a colorant and further containing a charge control agent composed of a calixarene derivative is suitable for the above purpose. And found that the present invention was completed.

That is, according to the present invention, by holding electric charges selectively on the surface of the developer carrying member, a large number of minute closed electric fields are formed in the vicinity of the surface of the developer carrying member. A one-component developer composed of a toner to which an auxiliary agent is externally added as necessary is supplied onto the body, and the developer is carried on the surface of the developer carrier by the minute closed electric field. An image forming method for visualizing an electrostatic latent image, wherein a toner containing at least a binder resin and a colorant and containing a charge control agent comprising a calixarene derivative is used as the toner. A method is provided.

In a developing method for forming a minute closed electric field (microfield), the toner layer on the developer carrying member is always stabilized with two or more layers, and the toner layer becomes thin to cause development unevenness and fog. In order to prevent the toner from being generated, a toner having stable charging characteristics is always required. In the present invention, however, by using a toner containing a charge control agent composed of a calixarene derivative, this point is pointed out. Is resolved.

In the toner used in the present invention, a calix [n] arene derivative is used as a charge controlling agent. A typical example thereof includes a repeating unit represented by the following formula (I), Cyclic oligomers having a number (n) of 4 to 8;

Embedded image[Wherein, R₁: Hydrogen, alkyl group, C_nH_TwonCOOR,
COC_m2H_{2m + 1}R_Two, R: hydrogen, alkyl group X, Z : Hydrogen, halogen, alkyl group, aralkyl
Group, Mino group Y : Hydrogen, halogen, alkyl group, COC_mH_{2m + 1},
Aralkyl group, Optionally substituted phenyl group, optionally substituted
Amino group, nitro group n : An integer of 1 to 3 m : Integer of 1 to 20] History of research on this calixarene, synthetic method, structural
For features and applications, see, for example, C. D. Gutsche et a
l. [Acc. Chem. Res.,16, 161 (1983); Pure & Appl, Ch
em., 60, 483 (1988)) or Shinkai et al. (Nikka., 1917 (19
88)]. Hereinafter, the present invention
[N] arene derivative preferably used in
The following shows a specific example.

[0021]

[Table 1- (1)]

[Table 1- (2)]

[Table 1- (3)]

As the binder resin used in the toner used in the present invention, all of those conventionally used as binder resins for toner are applied. Specifically, a homopolymer of styrene such as polystyrene, polychlorostyrene, polyvinyltoluene and a substituted product thereof; styrene /
p-chlorostyrene copolymer, styrene / propylene copolymer, styrene / vinyltoluene copolymer, styrene / vinylnaphthalene copolymer, styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer,
Styrene / butyl acrylate copolymer, styrene / octyl acrylate copolymer, styrene / methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer,
Styrene / butyl methacrylate copolymer, styrene / α
-Methyl chloromethacrylate copolymer, styrene / acrylonitrile copolymer, styrene / vinyl methyl ether copolymer, styrene / vinyl ethyl ether copolymer, styrene / vinyl methyl ketone copolymer, styrene / butadiene copolymer, Styrene / isoprene copolymer, styrene / acrylonitrile / indene copolymer,
Styrene-based copolymers such as styrene / maleic acid copolymer and styrene / maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyvinyl butyl butyral, Polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin,
Aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be mentioned, and these can be used alone or as a mixture of two or more.

As the colorant used in the toner used in the present invention, all pigments and dyes conventionally used as toner colorants are applied. Specifically, carbon black, lamp black, iron black, ultramarine,
Nigrosine dye, aniline blue, calco oil blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, phthalocyanine green, hansa yellow G, rhodamine 6C lake, chrome yellow, quinacridone, benzidine yellow, malachite green, malachite green hexalate, Examples include oil black, azo oil black, rose bengal, monoazo dyes and pigments, disazo dyes and pigments, and trisazo dyes and pigments.

Further, in the toner used in the present invention,
Synthetic waxes such as low molecular weight polyethylene and polypropylene, as well as vegetable waxes such as candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil, etc .; Animal waxes such as waxes; mineral waxes such as montan wax and ozokerite; oily waxes such as hardened castor oil, hydroxystearic acid, fatty acid amides and phenol fatty acid esters can be contained.

In the toner used in the present invention, in addition to the binder resin, the colorant and the like, various plasticizers (for the purpose of adjusting the thermal properties, electrical properties, physical properties, etc. of the toner as necessary) It is also possible to add auxiliary agents such as dibutyl phthalate and dioctyl phthalate, and a resistance adjuster (such as tin oxide, lead oxide, and antimony oxide). Further, additives other than the above-described binder resin, colorant, auxiliary agent, and the like can be added to the toner of the present invention, if necessary. Examples of the additive include fluidity imparting agents such as colloidal silica, titanium oxide, and aluminum oxide.

According to the image forming method of the present invention, as described above, a plurality of minute closed electric fields are formed in the vicinity of the surface of the developer carrier by selectively holding electric charges on the surface of the developer carrier. Supplying a one-component developer composed of a toner to which an auxiliary agent is externally added, if necessary, on the developer carrier;
The developer is carried on the surface of the developer carrying member by the micro-closed electric field, and the electrostatic latent image is visualized by the carried developer.

Hereinafter, such an image forming method will be described. FIG. 1 shows an outline of a typical developing device useful for carrying out this image forming method, focusing on a developer carrier. FIG.
, The toner 6 contained in the toner tank 70
Reference numeral 0 denotes a toner supply member (such as a sponge roller or a fur brush) 4 by a stirring blade (toner supply auxiliary member) 50.
0, and the toner 60 is
0 is supplied. On the other hand, the developer carrier (developing roller) 20 that has completed the development rotates in the direction of the arrow (for example, 40
0 rpm) to reach a contact portion with the toner supply member 40.
The toner supply member 40 rotates in a direction opposite to that of the developer carrier 20, charges the developer carrier 20 and the toner 60, and causes the toner 60 to adhere to the developer carrier 20. Further, the developer carrier 20 rotates, and the toner adhered on the developer carrier 20 is moved by a toner layer thickness regulating member (elastic blade) 30.
The charge is also stabilized while controlling the thickness, 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 DC, AC, DC superimposed AC, or pulse is applied to the developer carrier 20 and the toner supply member 40,
An 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 carrying member 20, as shown in FIG. 2, for example, a dielectric portion and a conductive portion are mixed on a surface thereof with a small area. The size of the area is
When the shape is circular, the diameter is 30 to 2000 μ
m, preferably small areas with a size of 100 to 400 μm are dispersed randomly or according to a certain rule.
As the area ratio, the area of the dielectric portion is preferably in the range of 50 to 80%.

The toner adhesion is as follows. First, the developer carrier 20 that has completed the development rotates in the direction of the arrow and comes into contact with the toner supply member 40. Here, the remaining toner in the non-image portion that has not been developed is mechanically and electrically scraped off by the toner supply member 40, and the dielectric portion is charged by friction. At this time, the charges of the developer carrier 20 and the toner by the previous development are fixed and initialized by friction. Next, the toner carried by the supply member 40 is charged by friction and adheres to the dielectric portion of the developer carrier 20 electrostatically. At this time, the polarity of the toner is opposite to the charge of the photosensitive member, and the dielectric portion of the developer carrier 20 has the same polarity. The electric field on the developer carrier 20 at this time becomes a microfield (closed electric field) as shown in FIG.
The electric field has a large electric field gradient, so that the toner can be attached in multiple layers. Further, since the attached toner has a closed electric field, it is strongly pulled toward the developer carrier 20 side,
It is difficult to leave.

The 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 (photoreceptor) 10 in the developing area 80 increases the electrode effect,
The toner on the developer carrier 20 becomes an electric field that easily adheres to the electrostatic latent image carrier 10 and development is performed.

Although many types of parts can be used for the developing device, as shown in Table 2, when only the preferable materials are used in view of the releasability from the toner and the durability.

[0032]

[Table 2]

Next, the method for producing the developer carrier used in the present invention will be described. For example, the following method is employed. (i) First, a metal roller whose surface is grooved is manufactured. The groove is formed by a method such as iris knurling. The grooves have a pitch of 0.1 to 0.5 mm and are processed at an angle of about 45 degrees with respect to the longitudinal direction of the roller. [See FIG. 3 (a)] (ii) Next, the grooved metal surface is coated with, for example, a fluororesin (Lumiflon LF200; manufactured by Asahi Glass Co., Ltd.) and cured and dried at 100 ° C. for about 30 minutes. The coating thickness is set so that the grooves are completely filled. [See; FIG. 3 (b)] (iii) Subsequently, the surface of the roller is cut or polished so that the conductive surface is mixed in a small area, and the conductive area is reduced to 2
Grind to 0-50%. [See; FIG. 3 (c)]

Further, in addition to the above-mentioned method, a conductive rubber material having a concave portion on the surface is formed by molding, and the concave portion is buried with an insulating material and polished by various methods using various materials. be able to.

However, in the developing system in which a large number of micro electric fields (microfields) are formed in the vicinity of the surface of the developer carrying member, the toner layer on the developer carrying member must be always stabilized by using two or more layers. Is difficult, the toner layer is thinned, the amount of toner to be developed is reduced, the density of the image area is reduced, or the toner layer is non-uniform, and uneven development occurs, and the density of the image area is non-uniform. Or fogging may occur. Also, when a filming phenomenon occurs on the developer carrier, filming is formed on the developer carrier, and the microfield effect is reduced,
The amount of toner held on the developer carrier decreases, and it becomes difficult to sufficiently develop the toner on the latent image carrier.

However, when a toner containing a charge control agent comprising the calix [n] arene derivative described above is used, pulverization of the toner on the developer carrier is suppressed, and as a result, the developer carrier Since filming is suppressed, a sufficient microfield effect is exhibited, and a high-density, high-quality image can be obtained over a long period of time by the method of the present invention.

[0037]

The present invention will be described in more detail with reference to the following examples. Parts represent parts by weight.

Example 1 Binder resin Styrene / acrylic copolymer 95 parts Release agent Low molecular weight polypropylene 5 parts Colorant carbon black 8 parts Charge control agent Exemplary compound (1) 3 parts

The mixture having the above composition was melt-kneaded, cooled, coarsely pulverized using a hammer mill, and then finely pulverized with a fine pulverizer using an air jet method. The obtained finely pulverized product was classified to have an average particle size of 11 μm. 0.2 parts of colloidal silica was added to and mixed with 100 parts of the particles to obtain a toner.

Next, a developing roller having a cross section as shown in FIG. 3 (c) [FIG. 3 (a)] (dielectric part and conductor part are mixed in a very small area, and their area ratio is 50% Things)
Was prepared, the toner was mounted on the developing device, and an image was formed. As a result, a clear image with high image density and no background stain was obtained. Furthermore, continuous 5
Even after running 000 sheets, the toner was not filmed on the developing roller, and a clear image was maintained.

Example 2 Binder resin 95 parts of styrene / acrylic copolymer Release agent Low molecular weight polypropylene 5 parts Colorant carbon black 8 parts Charge control agent Exemplary compound (2) 2 parts

The mixture having the above composition was melt-kneaded, cooled, coarsely pulverized by using a hammer mill, and then finely pulverized by a pulverizer using an air jet method. The obtained finely pulverized product was classified to have an average particle size of 12 μm. To 100 parts of the particles, 0.3 part of titanium oxide was added and mixed to obtain a toner.

Next, a developing roller having a cross section as shown in FIG. 3 (c) [FIG. 3 (a)] (dielectric part and conductor part are mixed in a very small area and the area ratio is 50%) ) Was prepared, the toner was mounted on the developing device, and an image was formed. As a result, a clear image with high image density and no background contamination was obtained. Further, even during the continuous running of 5000 sheets, the toner was not filmed on the developing roller, and a clear image was maintained.

Example 3 Binder resin Styrene / acrylic copolymer 95 parts Release agent Low molecular weight polypropylene 5 parts Colorant carbon black 8 parts Charge control agent Exemplary compound (15) 2 parts

The mixture having the above composition was melt-kneaded, cooled, coarsely pulverized by using a hammer mill, and then finely pulverized by an air jet type pulverizer. The obtained finely pulverized product was classified to have an average particle size of 11 μm. 0.2 parts of colloidal silica was added to and mixed with 100 parts of the particles to obtain a toner.

Next, a developing roller having a cross section as shown in FIG. 3 (c) (FIG. 3 (a)) (dielectric part and conductor part are mixed in a very small area and the area ratio is 50%) ) Was prepared, the toner was mounted on the developing device, and an image was formed. As a result, a clear image with high image density and no background contamination was obtained. Further, even during the continuous running of 5000 sheets, the toner was not filmed on the developing roller, and a clear image was maintained.

Comparative Example A toner for comparison was prepared in the same manner as in Example 1 except that the charge control agent was not blended in Example 1, and the toner was charged into the same developing device as in Example 1. Then, when an image was formed under the same conditions, an image having a low density and a lot of background stains was obtained.

[0048]

According to the image forming method of the present invention, since a toner containing a charge control agent comprising the calix [n] arene derivative is used, a large number of toners are provided near the surface of the developer carrying member. In the developing method for forming a minute closed electric field, two or more layers of toner can be stably and uniformly laminated on the developer carrier, and toner filming on the developer carrier is suppressed, and a high High quality images can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of a developing device that forms a microfield electric field on a developer carrier useful for carrying out the present invention, focusing on a developer carrier portion.

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

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

[Explanation of symbols]

 10 Electrostatic latent image carrier 20 Toner transport member 30 Toner layer thickness regulating member 40 Toner supply member 50 Stirrer blade 60 Toner 70 Toner tank 80 Development area

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-106768 (JP, A) JP-A-2-201378 (JP, A) JP-A-55-62469 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) G03G 15/08-15/09 G03G 9/08

Claims (2)

(57) [Claims] An electric charge is selectively retained on a surface of a developer carrier to form a large number of minute closed electric fields near the surface of the developer carrier. Accordingly, a one-component developer composed of a toner to which an auxiliary agent is externally added is supplied, and the developer is carried on the surface of the developer carrier by the minute closed electric field. An image forming method for forming an image, wherein a toner containing at least a binder resin and a colorant and containing a charge control agent comprising a calixarene derivative is used. 2. A calixarene derivative represented by the following formula 1.
2. A compound having the repeating unit shown in claim 1.
Image forming method. Embedded image[Wherein, R₁: Hydrogen, alkyl group, C_nH_TwonCOOR,
COC_m2H_{2m + 1} R_Two, R: hydrogen, alkyl group X, Z : Hydrogen, halogen, alkyl group, aralkyl
Group, Mino group Y : Hydrogen, halogen, alkyl group, COC_mH_{2m + 1},
Aralkyl group, Optionally substituted phenyl group, optionally substituted
Amino group, nitro group n : An integer of 1 to 3 m : An integer of 1 to 20]