JPH103185A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method which stabilizes the electrostatic charge and transportation of toner over a long period of time, makes it possible to obtain a stable image density free from fogging and unequal density, and hardly generates dirt, color mixing, etc. SOLUTION: A developer carryer having a surface resin layer contg. a positive charge control agent is used as the developer carryer, in the image forming method for developing the electrostatic latent image on a latent image holder by using the developer layer on the developer carryer. In addition, the development is executed in a range of 0.03 to 0.09 of the value of M/D when the toner weight per unit area on the developer carryer is defined as M(mg/cm<2> ) and the volume average particle size of the toners as D(μm). S solid lubricant having an average particle size of 0.2 to 10μm is preferably incorporated into the surface resin layer of the developer carryer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming method using a non-magnetic one-component developer.

[0002]

2. Description of the Related Art At present, as a dry developing method in various electrostatic copying systems put into practical use, a two-component developing system using a carrier such as toner and iron powder and a one-component toner developing system using no carrier are known. Have been. In the two-component developing method, the developer deteriorates due to the toner particles adhering to the carrier surface, and the toner is consumed only to reduce the concentration ratio of the toner in the developer. Since a density controller or the like for keeping the mixing ratio constant is required, there is a disadvantage that the developing device becomes large. On the other hand, the one-component developing method does not have the above-mentioned problems because it does not use a carrier, and has advantages such as downsizing and weight reduction of the apparatus. Therefore, the developing method is becoming mainstream.

The one-component toner developing system is roughly classified into a magnetic one-component developing system using a magnetic toner and a non-magnetic one-component developing system using a non-magnetic toner. The magnetic one-component developing system holds and develops a magnetic toner by using a developer carrier provided with a magnetic field generating means such as a magnet therein, and has recently been put to practical use in small printers and the like. However, this method is difficult to use for colorization because a magnetic toner containing a black magnetic substance such as magnetite is used inside the toner. On the other hand, the non-magnetic one-component development method does not use a magnetic material for the toner, so it is suitable for colorization. In addition, since no magnet is used for the developer carrier, it is possible to reduce the weight and cost. ,
In recent years, it has begun to be used in small full-color printers and the like. By the way, the two-component developing system has a stable charging and conveying member called a carrier, and the magnetic one-component developing system has a stable conveying and layer forming means of a magnetic force of a magnet roll. On the other hand, the non-magnetic one-component developing system does not have such stable charging and conveying means. Therefore, in the non-magnetic one-component developing method, it is necessary to hold the toner on the developer carrier mainly by electrostatic force.
It is required to have higher charging and stable charging characteristics. In particular, when the charge of the toner is low, problems such as fouling and dirt in the non-image area due to fouling in the apparatus and color mixing are likely to occur, so that a more stable design is required.

Conventionally, a charge control agent has been added to the inside of a toner to improve the charge amount of the toner, thereby achieving a relatively high charge amount. Unless a charge control agent is added, the effect cannot be obtained, and there are various problems such as an increase in the amount of addition of the charge control agent which adversely affects fixing performance and color characteristics. is the current situation. In addition, since a metal such as aluminum or stainless steel is generally used as the developer carrier, there is a problem that a sufficient charge cannot be given to the toner. In fact, the toner is actually mixed with a charge control agent.

In recent years, a number of surface-treated developer carrying members (charging members) have been proposed. However, even if they are applied to a developing method using a non-magnetic one-component toner, the charging property is insufficient. Or, on the contrary, the charge amount becomes excessive and the toner transport amount on the developer carrying member becomes too large, so that the charge amount distribution of the toner becomes broad and eventually, the problem of fouling and dirt inside the machine due to fog and dirt is caused. It has not been eliminated. Therefore, there are still many problems concerning stabilization of charging and layer formation in non-magnetic one-component development.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances in the prior art, and has been made to solve the problems. That is, an object of the present invention is to provide a non-magnetic monocomponent which stabilizes the charging and transport of the toner for a long time and obtains a stable image density without fog or density unevenness even when a toner containing no charge controlling agent is used. An object of the present invention is to provide a developing type image forming method. It is another object of the present invention to provide an image forming method of a non-magnetic one-component developing method in which dirt, color mixing, and the like hardly occur for a long period of time.

[0007]

The inventors of the present invention have conducted various studies to solve the above-mentioned problems. As a result, the present inventors have found that a surface resin layer containing a resin containing a positive charge control agent, or a solid lubricant. Image forming by using a developer carrier having a surface resin layer in which a developer is dispersed, and controlling a ratio of a toner transport amount onto the developer carrier and a particle diameter of the toner to be used to be within a certain range. It has been found that the above-mentioned object can be achieved by carrying out, and the present invention has been completed.

That is, the image forming method of the present invention is an image forming method for developing an electrostatic latent image on a latent image holding member using a developer layer on a developer holding member. A toner having a surface resin layer containing a positive charge control agent is used, the weight of the toner per unit area on the developer carrier is M (mg / cm ² ), and the volume average particle diameter of the toner is D ( μm), the value of M / D is 0.03 to 0.0
9 is performed. The developer carrier used in the present invention preferably has a surface resin layer containing a lubricant having an average particle diameter of 0.2 to 10 μm, and the developer used in the present invention is preferably a non-magnetic monocomponent. It is preferably a system developer.

[0009]

Embodiments of the present invention will be described below in detail. The image forming method of the present invention includes a latent image forming step of forming a latent image on a latent image holding member, and forming a latent image on the latent image holding member by using a thin layer-formed developer on a developer holding member. Used in an image forming apparatus having a developing step of developing, a transfer step of transferring a toner image on a latent image holding member to a transfer member, and a fixing step of thermally fixing the toner image on the transfer member,
It is used in a full-color developing device using four color toners of yellow, magenta, cyan and black.

As the above-described latent image forming step, a conventionally known method can be applied, and the latent image forming step such as a photosensitive layer or a dielectric layer is performed by an electrophotographic method or an electrostatic recording method. To form an electrostatic latent image. As the photosensitive layer of the latent image holding member used in the present invention, known materials such as organic and amorphous silicon can be used. Further, as the cylindrical holder, one obtained by a known manufacturing method such as extruding aluminum or an aluminum alloy and then performing surface processing is used.

In the developing step, a thin layer of toner supplied by a toner supply roll is formed on a rotating cylindrical body of a developer carrier (hereinafter, referred to as a “development roll”) by an elastic blade or the like to a development nip. Conveyed, the developing roll and the latent image holding member holding the electrostatic latent image are brought into contact with each other in the developing section, or a predetermined gap is provided, and a bias is applied between the developing roll and the latent image holding member. The electrostatic latent image is developed with toner while applying the voltage.

As the developing roll used in the present invention, aluminum which has been subjected to surface treatment such as polishing and blasting,
A resin layer containing a positive charge control agent is applied to the surface of a metal substrate such as SUS stainless steel to form a surface resin layer. In the present invention, as the resin used for forming the surface resin layer of the developing roll, various resins such as polyethylene resin, styrene resin, polymethyl methacrylate resin (PMMA), phenol resin, epoxy resin, polyester resin, polyurethane resin, silicone resin, etc. Although various resins can be used, PMMA, a phenol resin, a silicone resin, or the like, which has chargeability without being largely affected by an environmental change, is preferable in order to facilitate charge control.

The positive charge control agent used in the surface resin layer includes a quaternary ammonium compound, a nigrosine dye, a triphenylmethane dye, a polyamine compound,
Examples thereof include an imidazole derivative, and in order to obtain uniform charging properties, it is preferable that the compound be soluble in the above-described resin solution. In the present invention, it is preferable to add a solid lubricant to the surface resin layer of the developing roll. For this solid lubricant, for example, molybdenum disulfide, boron nitride, graphite, etc. are appropriately used in consideration of the dispersibility in the resin, the chargeability of the toner, the transportability of the toner, and the like. The average particle diameter is 0.2 to 10 μm
Are preferred. When the average particle diameter of the solid lubricant is smaller than 0.2 μm, the effect of suppressing the adhesion of the toner due to charge-up on the surface of the developing roll becomes insufficient. As the dispersion decreases, the charge amount distribution of the toner becomes broad. The amount of the solid lubricant is preferably in the range of 20 to 70% by weight in the surface resin layer. If the amount added is less than 20% by weight,
The effect of suppressing the adhesion of the toner becomes insufficient due to the charge-up. On the other hand, if it exceeds 70% by weight, the strength of the surface resin layer is reduced, so that problems such as peeling of the surface resin layer of the developing roll occur.

As a method of manufacturing the developing roll used in the present invention, a solid lubricant is dispersed as necessary in a solution in which the above-mentioned resin is dissolved, and then a known coating method such as spraying or dipping is used. Examples of the method include a method of applying the composition on the surface of the substrate and drying the composition, or, if necessary, curing the composition. The formation of the toner layer on the developing roll is performed by bringing an elastic blade into contact with the surface of the sleeve. As the material of the elastic blade, it is preferable to use a rubber elastic material such as silicone rubber or urethane rubber.In order to control the charge amount of the toner, an organic or inorganic material is added to these elastic materials and dispersed. Is also good.

As a method of developing a four-color toner, four developing machines are arranged around a photoreceptor, and for each toner,
A method of repeating the charging, exposure and development processes for 4 cycles,
And a method of charging, exposing and developing the four-color toner in one cycle. The method of superimposing the four-color toner includes a method of transferring the toner image formed on the photoconductor one by one on a transfer drum around which a transfer paper is wound and superimposing the toner image, and a method of transferring the toner image formed on the photoconductor to the transfer body. A method is used in which the color toner image is transferred onto the transfer member, and the color toner image is superimposed on the transfer member, and then transferred onto the transfer paper at one time. .
As a transfer unit, a known unit such as a contact type in which a transfer roll is pressed against a latent image holding member or a non-contact type using a corotron is used.

In the cleaning step, the toner remaining on the latent image holding member without being used for transfer in the transfer step is removed.
The cleaning means which is removed by a cleaner and which is used in the present invention includes known means such as blade cleaning or roller cleaning. Elastic rubber such as silicone rubber or urethane rubber is used for blade cleaning. The fixing process is
The toner image transferred to the transfer member is fixed by a fixing device. As a fixing unit, a heat fixing method using a heat roll is preferable. Alternatively, oilless fixing is performed in which a release agent is added to the toner to reduce the size of the apparatus.

The developer used in the present invention basically does not require a charge control agent, and contains at least a binder resin and a colorant, and can be obtained by adding a release agent and the like as necessary. Fine particles are externally added to toner particles, and the toner is particularly suitable for a non-magnetic one-component developing system.

The binder resin used in the developer of the present invention includes styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isobutylene, vinyl acetate, vinyl propionate, vinyl benzoate and butyric acid. Vinyl esters such as vinyl, α-methylene such as methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, dodecyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymerization of aliphatic monocarboxylic acid esters, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, and vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone And it can be exemplified a copolymer. Particularly typical binder resins include polystyrene and
Styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, polypropylene, and further, polyester , Polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

Examples of colorants for toner include carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, copper phthalocyanine, malachite green oxalate, lamp black, and rose bengal. , C.I. I. Pigment Red 4
8: 1, C.I. I. Pigment red 122, C.I. I.
Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 12, C.I.
I. Pigment yellow 17, C.I. I. Pigment
Blue 15: 1, C.I. I. Pigment Blue 15: 3
Are used.

Further, a releasing agent may be added to the developer used in the present invention for the purpose of preventing gloss and improving anti-offset property. As the release agent, a paraffin having 8 or more carbon atoms, polyolefin, or the like is preferable, and examples thereof include paraffin wax, paraffin latex, microcrystalline wax, and the like, or polypropylene, polyethylene, and the like. These may be used alone or in combination. . The amount of these additives is preferably in the range of 0.3 to 10% by weight.

In the present invention, fine particles are externally added to impart appropriate fluidity and chargeability to the developer. The fine particles include hydrophobic silica, titania,
Fine powder of an inorganic compound such as alumina, fine powder of an organic compound such as a fatty acid or a derivative thereof and a metal salt thereof, fine powder of a resin such as a fluororesin, an acrylic resin or a styrene resin, and the like. , Or in combination. In particular, the fine powder of an inorganic compound having an average particle diameter of 10 to 500 nm is effective in suppressing an increase in the amount of toner transported due to charge-up. Average particle size is 500n
If it is more than m, it tends to cause density unevenness.
These fine particles are 0.1 to 100 parts by weight of the toner.
It is used in an amount of 3 parts by weight, preferably 0.3 to 1.5 parts by weight. If the external addition amount is less than 0.1 parts by weight, the toner surface coverage by the fine powder is low, so that sufficient fluidity cannot be given to the toner. On the other hand, if the external addition amount is more than 3 parts by weight, The fine powder adheres to the surface of the photoreceptor and easily causes comet and filming.

The particle diameter of the toner used in the present invention is preferably in the range of 4 to 10 μm, more preferably 6 to 9 μm in terms of volume average particle diameter. When the volume average particle size is 4 μm or less, the fluidity is remarkably reduced, so that good layer formation is not performed, and therefore, it is likely to cause fog and dirt. On the other hand, when the thickness is 10 μm or more, not only the resolution is lowered and a high image quality is not obtained, but also the charge amount per unit weight of the developer is reduced, so that the maintenance of layer formation is low and fog and dart are generated. It will be easier.

In the present invention, the weight of the toner conveyed on the developing roll is represented by M (mg / cm ² );
When the volume average particle diameter of the toner to be used is represented by D (μm), it is necessary to form an image so that the value of M / D is in the range of 0.03 to 0.09. If the value of M / D is smaller than 0.03, a sufficient image density cannot be obtained, and uneven density occurs. On the other hand, M /
When the value of D is larger than 0.09, the distribution of the charge amount of the toner becomes broad, and fog and dirt are easily generated.

The developer used in the present invention can be produced by any known method, but a kneading and pulverizing method is particularly preferable. That is, after preliminarily mixing the binder resin and the colorant, the mixture is melted and kneaded in a kneader, and the obtained kneaded material is cooled, pulverized, and then classified. A method of adding and mixing fine particles as an agent is preferable. As the kneader, a Banbury mixer, a pressure kneader, a continuous mixer, an extruder, or the like is used.

The reason why the structure adopted in the present invention is effective is considered as follows. First, by providing a surface resin layer formed of a resin containing a positive charge control agent on the surface of the developing roll, it becomes possible to apply charge to toner not containing a charge control agent. However, simply applying a charge to the surface resin layer of the developing roll, in particular, causes the toner existing in the vicinity of the surface to charge up and strongly adhere to the surface of the developing roll. When the toner layer is formed, the transport amount increases, and due to the mutual charging between the toners, particularly the charging of the toner in the upper layer portion is reduced, which may cause fog or dirt. for that reason,
When the solid lubricant is further dispersed in the surface resin layer of the developing roll, even if the toner near the surface is charged up, the surface resin layer itself has lubricity. This is effective in suppressing strong adhesion of toner to the surface and an increase in the amount of toner transported. When an inorganic oxide having a relatively large particle diameter is used as an external additive of the toner,
The external additive acts as a roller between toners under the pressure of the layer forming blade, and this is also effective in suppressing an increase in the transport amount. In the present invention, the toner weight per unit area on the developing roll is determined by measuring the toner transferred using a tape having a fixed area after the toner is conveyed onto the developing roll using an apparatus described later. Determined by
The particle size of the toner used in the present invention is a particle size analyzer TAII manufactured by Coulter Counter Co., and an aperture diameter of 100 μm.
m.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to embodiments. Example 1 <Developing Roll> A resin solution obtained by ultrasonically dispersing a composition composed of the following materials on an aluminum substrate blasted to a surface roughness (Ra) of 0.4 μm was applied to a thickness of 10 μm.
m with a push-up coater, 120 ° C
For 1 hour to produce a developing roll. Resin: polymethyl methacrylate resin (PMMA) 8 parts by weight Positive charge control agent: quaternary ammonium salt 2 parts by weight (P51: manufactured by Orient Chemical Industries) Solid lubricant: molybdenum disulfide (average particle diameter 0.5 μm) 5 parts by weight Parts Solvent: methyl ethyl ketone 15 parts by weight <Toner> Binder resin: polyester resin 96 parts by weight (terephthalic acid / bisphenol A ethylene oxide adduct) (weight average molecular weight Mw: about 10,000, Tg: 67 ° C.) Pigment: copper phthalocyanine 4 parts by weight of blue pigment After mixing the above materials with a Henschel mixer, the extruder was used to set a temperature of 120 ° C and a screw rotation speed of 3
Melt kneading was performed under the conditions of 00 rpm and a supply speed of 150 kg / h. After cooling the obtained kneaded material and coarsely pulverizing,
By pulverizing with a jet mill, and further classifying the pulverized product with an air classifier, the volume average particle diameter D ₅₀
Was 8.0 μm. Next, 0.5 parts by weight of silicone oil-treated silica and 1.0 parts by weight of titanium oxide having a particle diameter of 30 nm were mixed with 100 parts by weight of the toner particles using a Henschel mixer to obtain a toner. The above-described developing roll and toner are used in the image forming apparatus shown in FIG. 1, and are used in a high-temperature and high-humidity environment (temperature 28 ° C./85% RH) and a low-temperature and low-humidity environment (temperature 10 ° C./humidity 3).
(0% RH), 5,000 print tests were performed. Table 1 shows the results.

(Image Forming Apparatus) FIG. 1 shows an image forming apparatus used for image formation for evaluating image quality and the like in the present invention. The photosensitive drum 1 and the developing roll 3 were arranged so as to have a constant gap. The photosensitive drum 1 is charged by a roll charger 2 and then exposed to laser light to form an electrostatic latent image, and an AC voltage and a DC voltage are applied to the developing roll 3 and the developer supply roll 4. Then, the electrostatic latent image was developed. Layer forming blade 5 made of silicone rubber
Was brought into contact with the developing roll 3 at a constant linear pressure to form a thin layer of toner. Reference numeral 6 denotes a roll transfer device, and reference numeral 7 denotes a blade type cleaner.

Example 2 Except that the solid lubricant added to the surface resin layer of the developing roll was changed to graphite (average particle diameter: 4 μm),
An image was formed and evaluated in the same manner as in Example 1. Example 3 An image was formed and evaluated in the same manner as in Example 1 except that the resin used for the surface resin layer of the developing roll was changed to polycarbonate, and the solvent was changed to toluene (20 parts by weight).

Comparative Example 1 An image was formed and evaluated in the same manner as in Example 1 except that the positive charge control agent was not used in the surface resin layer of the developing roll. Comparative Example 2 An image was formed in the same manner as in Example 1, except that an aluminum base (Ra: 1 μm) having no surface resin layer was used as a developing roll, and a toner not containing titanium oxide was used. An evaluation was performed.

[0030]

[Table 1] In Table 1, A is a high temperature and high humidity environment (temperature 28 ° C., humidity 85% R
H) is the measurement and evaluation, and C is the measurement and evaluation in a low-temperature and low-humidity environment (temperature 10 ° C., humidity 30% RH). In “density unevenness”, ○ indicates a density difference of 0.1.
Less than, Δ represents a concentration difference of less than 0.1 to 0.3, ×
Indicates that the density difference is 0.3 or more. In “fogging” and “in-machine dirt”, ○ means that there is no occurrence and is good, Δ means that there is some occurrence, and X means that there is occurrence and there is a problem. In the “Comprehensive Evaluation”, ○ means good, Δ means usable level, and × means a problem.

[0031]

According to the image forming method of the present invention, even when the toner is deteriorated by continuous use, the charge distribution of the toner is sharp and the charge amount is small, so that the image density does not fluctuate for a long time. In addition, it is possible to obtain an image of excellent image quality which does not cause problems such as low developability, fogging and in-machine contamination.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus used for image formation for evaluating image quality and the like in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum, 2 ... Roll charger, 3 ... Development roll, 4 ... Developer supply roll, 5 ... Layer forming blade, 6 ...
Roll transfer unit, 7 ... blade type cleaner.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hirora Okuno 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. Inventor Kotaro Yoshihara 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd.

Claims (3)

[Claims] 1. An image forming method for developing an electrostatic latent image on a latent image holding member using a developer layer on a developer carrying member,
A developer having a surface resin layer containing a positive charge control agent was used as the developer carrier, the toner weight per unit area on the developer carrier was M (mg / cm ² ), and the volume average of the toner was An image forming method, wherein the M / D value is in the range of 0.03 to 0.09 when the particle diameter is D (μm). 2. The surface resin layer has an average particle size of 0.2 to 10
2. The image forming method according to claim 1, wherein a developer carrier containing a solid lubricant having a thickness of [mu] m is used. 3. The image forming method according to claim 1, wherein a non-magnetic one-component developer is used as the developer.