JPH0822138A - Non-magnetic one-component developer and developing method using it - Google Patents

Abstract

PURPOSE:To prevent the deterioration of image quality such as thereof an roughness image and the increase of fogging from occurring even at a repeated developing time by respectively specifying volume averaged grain size, the number proportion of grains having specified grain size, proportion by volume and the standard deviation of volume grain size distribution. CONSTITUTION:This non-magnetic one-component developer is constituted so that the volume averaged grain size thereof is specified to be 7.0-12.0mum and the number proportion of the grains whose grain size is <=5mum is specified to be <=13.0 pieces %, the proportion by the volume of the grains whose grain size is <=16mum is specified to be 2.0 volume % and the standard deviation of the volume grain size distribution is specified to be <=2.7. After the developer is supplied to a developing roller 11 and the thin layer of the developer 5 is formed on the surface of the roller 11 by using a developer layer regulation blade 15 pressed to the roller 11 by linear load being 40-100g/cm, the developer 5 is supplied to an electrostatic latent image on a photoreceptor drum 9 provided so as to be proximately faced to the roller 11 and the electrostatic latent image is developed. Thus, the deterioration of the image quality such as the fogging on the drum 9 and the image and the roughness of the image is prevented from occurring even at the repeated developing action time because of continuous use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic one-component developer for developing an electrostatic charge image used for developing an electrostatic latent image by electrophotography.

[0002]

2. Description of the Related Art In electrophotography, in general, an electrostatic latent image is formed on a photoconductor using a photoconductive substance, and then fine particles called toner are selectively formed on the obtained latent image. The latent image is made visible by adhering and developing. After transferring the visualized toner to a transfer material such as paper, heat and pressure,
Alternatively, an image is formed by fixing with solvent vapor or the like.

In order to visualize an electrostatic latent image, an image forming method using a two-component developing system in which a developer composed of a toner and a carrier is used for development is widely used. This method has an advantage that a high-quality image can be easily obtained because a material having a wide range of characteristics can be used by combining a toner and a carrier with relatively little environmental dependence.

On the other hand, in recent years, a full-color image forming method using an electrophotographic system has appeared and is being actively developed. This system mainly reproduces colors with three color developers of cyan, magenta, and yellow, and a developer layer of the above three colors on the material to be transferred, or four colors obtained by adding black to the above three colors. A developer layer is formed, and is heated and melted and fixed by a flash, a heat roller, an oven or the like. Since three or four color developers are used, three or four sets of developing devices are also required, and when the two-component developing method is used, the weight and volume of the image forming unit becomes very large. Further, in order to reproduce a full-color image, it is necessary to finely adjust the density of three or four colors, and the toner density in the developer must be strictly controlled.

Attention has therefore been paid to a non-magnetic one-component developing method in which toner is developed by friction and / or contact charging with a metal or synthetic resin pressure contact member. According to this method, since no carrier is required, it is possible to reduce the weight and size of the image forming unit, and the maintenance is easy. Further, since the distance between the photoconductor and the developing sleeve is shorter than that in the two-component developing method, high-definition developing can be performed at a low potential.

However, since image formation with such a developer is generally repeated, even if a good image is obtained in the initial stage of use, after repeated use, the particle size distribution and charge amount of the developer may change. However, there is a drawback in that the image quality is apt to deteriorate due to fluctuations, roughening of the image, and increase of fog.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art. Even in repeated development by continuous use, deterioration of image quality such as roughening of image or increase of fog is caused. It is an object of the present invention to provide a non-magnetic one-component developer that does not cause this.

The present invention also relates to repeated development by continuous use using such a non-magnetic one-component developer,
It is an object of the present invention to provide a non-magnetic one-component developing method for forming a high-quality image by preventing image deterioration such as fogging on the electrostatic latent image carrier and the image, and image roughness.

[0009]

The developer of the present invention comprises particles having a volume average particle size of 7.0 to 12.0 μm and particles having a particle size of 5 μm or less 13.0% by number or less and particles having a particle size of 16 μm or more.
2.0% by volume or less, standard deviation of volume particle size distribution 2.7
It is characterized by the following.

The non-magnetic one-component developing method of the present invention is
It is housed in a developer container and has a volume average particle size of 7.0-12.
A non-magnetic one-component developer having a particle size of 0 μm and a particle size of 5 μm or less 13.0 number% or less, a particle size of 16 μm or more 2.0% by volume, and a standard deviation of volume particle size distribution of 2.7 or less is applied to a developing roller. Developer supplying step of supplying, developer thin layer forming step of forming a thin layer of developer on the surface of the developing roller using a developer layer regulating blade pressed against the developing roller with a linear pressure of 40 to 100 g / cm And a developing step of developing the electrostatic latent image by supplying a developer to the electrostatic latent image on the electrostatic latent image carrier provided facing the developing roller.

[0011]

According to the present invention, the linear pressure of the developer layer regulating blade pressed against the developing roller is set to 40 to 100 g / cm, and a) volume average particle diameter is 7.0 to 12.0 μm, b) particle. Particles with a diameter of 5 μm or less 13.0% by number or less, c) Particles with a particle size of 16 μm or more 2.0% by volume, d) Standard deviation of volume particle size distribution 2.7 or less By using a developer satisfying the conditions It is possible to prevent the fogging on the image and the drum and the image roughness.

When the pressing force of the developer layer regulating blade against the developing roller is smaller than the linear pressure of 40 g / cm, the thickness of the developer layer formed on the outer peripheral surface of the developing roller becomes large and the charge amount of the developer decreases. Fog is likely to occur. Further, when the linear pressure is more than 100 g / cm, problems such as easy crushing of the developer and filming of the developer on the developing roller are likely to occur.

When the volume average particle diameter of the developer is smaller than 7.0 μm, it is difficult to stably produce the developer, or cleaning failure easily occurs. On the other hand, 1
When it is larger than 2.0 μm, the image density is satisfactory, but
The image lacks sharpness.

If the proportion of the developer having a particle size of 5 μm or less is larger than 13.0% by number, the developer layer regulating blade is not sufficiently charged and fog is apt to occur.

When the proportion of the developer having a size of 16 μm or more is more than 2.0% by volume, it becomes difficult for the developer to pass through the developer layer regulating blade, and the developer having a size of 16 μm or more in the repeated development by continuous use. The ratio increases and the graininess of the image becomes noticeable.

As the binder resin used in the developer of the present invention, a polyester resin which has been conventionally used as a binder resin for a developer can be used. Other binder resins include polystyrene, poly-p
-Chlorostyrene, polyvinyltoluene, styrene-p
-Homopolymers of styrene such as chlorostyrene copolymers and styrene-vinyltoluene copolymers and their substitutes, and copolymers thereof, styrene-methyl acrylate copolymers, styrene-ethyl acrylate copolymers and styrene -Copolymer of styrene and acrylic ester such as n-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer and styrene-n-butyl methacrylate copolymer A copolymer of styrene and a methacrylic acid ester, etc. may be used. Others styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-butadiene copolymer, styrene-vinyl methyl ketone copolymer, styrene-acrylonitrile indene copolymer and styrene-maleic acid ester copolymer Styrene-based copolymers of styrene and other vinyl-based monomers such as polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid, phenol resin,
Aliphatic or alicyclic compounds, hydrocarbon resins, petroleum resins, chlorinated paraffins, etc. may be used alone or in combination.

The colorant used in the developer of the present invention includes:
Carbon black and organic or inorganic pigments and dyes are used. Although there are no particular restrictions, acetylene black, furnace black, thermal black, channel black, Ketjen black, etc. are used as carbon black. Examples of face dyes include Fast Yellow G, Benzidine Yellow, Indian Fast Orange, Irgadine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Resole Red 2G, Lake Red C, Rhodamine FB, Rhodamine B Lake, Phthalocyanine blue, pigment blue, brilliant green B, phthalocyanine green, quinacridone and the like are used. These facial dyes can be used alone or in combination.

In the developer of the present invention, waxes for improving anti-offset characteristics, a charge control agent for controlling the amount of triboelectric charge, and the like may be blended, if necessary. As the charge control agent, for example,
Metal chelate of alkylsalicylic acid, chlorinated polyester, polyester with excess acid groups, chlorinated polyolefin,
Metal salts of fatty acids, negative polarity control agents such as fatty acid soap, dimethylaminoethyl methacrylate-styrene copolymer,
Examples of positive polarity control agents such as fluorine-based surfactants and hydrophobic silica.

As a mixing and dispersing means, a wet dispersion method using a high speed dissolver, a roll mill, a ball mill, or the like, or
A melt kneading method using a roll, a pressure kneader, an internal mixer, a screw type extruder, or the like can be used, and as a mixing means, a ball mill, a V-type mixer, a Forberg, a Henschel mixer or the like can be used. it can. Further, as means for coarsely pulverizing the mixture,
For example, hammer mill, cutter mill, jet mill,
A roller mill, a ball mill, etc. can be used. Further, as a means for finely pulverizing the coarsely pulverized product, a jet mill, a high speed rotary pulverizer or the like can be used. Further, as a means for classifying the finely pulverized product, an airflow classifier or the like can be used.

In the developer of the present invention, an external additive can be blended if necessary. As such external additives, silica fine particles, metal oxide fine particles, cleaning aids and the like are used. Examples of the silica fine particles include silicon dioxide, aluminum silicate, sodium silicate, potassium silicate, zinc silicate, magnesium silicate and the like. Examples of the metal oxide fine particles include zinc oxide, titanium oxide, aluminum oxide, zirconium oxide, strontium titanate, and barium titanate. Examples of the cleaning aid include resin fine powders of polymethylmethacrylate, polyvinylidene fluoride, polytetrafluoroethylene and the like. As these external additives, those subjected to surface treatment such as hydrophobization can also be used.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an embodiment of a printer as a non-magnetic one-component developing device of the present invention.

A toner container 3 for accommodating a non-magnetic toner 5 (hereinafter abbreviated as toner 5) as a developer of the embodiment of the present invention is provided in a developing device main body 1 (hereinafter abbreviated as main body 1) of the present embodiment. (Hereinafter abbreviated as container 3). In addition, a mixer 7 for stirring the toner 5 is provided in the container 3 in the direction of arrow a.
It is rotatably installed. Further, the main body 1 is provided with three rotators rotatable in the arrow direction, that is, the photoconductor drum 9, the developing roller 11, and the toner supply roller 13 adjacent to each other. The photoconductor drum 9 has a rotary base 8 inside and a negatively chargeable organic photoconductor 1 on its surface.
It is an image carrier having 0, and an electrostatic latent image is formed when a document image is irradiated as a light signal on the organic photoreceptor 10 by a laser. The photosensitive drum 9 is connected to the ground. Next to the photosensitive drum 9, there is a developing roller 11 for attaching the charged toner 5 onto the electrostatic latent image on the photosensitive drum 9 to form a toner image. Developing roller 11
Is covered with a member having both conductivity and elasticity. Next to the developing roller 11, there is a toner supply roller 13 for supplying the toner 5 contained in the container 3 onto the developing roller 11. A blade 15 having a function of restricting the amount of toner 5 supplied to the developing roller 11 and at the same time frictionally charging the toner 5 and a blade holder 17 for supporting the blade 15 are fixedly attached to the upper portion of the developing roller 11. ing. Further, below the developing roller 11, there is provided a recovery blade 19 having a function of recovering the toner 5 not used for development among the toner 5 supplied to the developing roller 11 and returning it to the container 3. Below the photoconductor drum 9 is a transfer device 21 for moving the toner image formed on the photoconductor 10 onto a transfer material.

The developing process in the developing device having such a structure is as follows. First, the toner 5 in the container 3 is sent to the toner supply roller 13 while being stirred by the mixer 7. Next, the toner 5 is supplied to the supply roller 13
To a developing roller 11 to form a thin layer of toner 5 on the surface of the developing roller 11. When forming a thin layer, the toner supply amount from the blade 15 to the developing roller 11 is regulated, and at the same time, the toner on the developing roller 11 is removed by the blade 15
The resulting flattening creates friction between the lamina and the blade. Due to this friction, the toner 5 is charged. By the way, the surface of the negatively chargeable organic photoconductor 10 on the photoconductor drum 9 is uniformly charged to about -500 to -550V by a charger (not shown). When the original image is directly irradiated onto the charged organic photoconductor 10 as a light image, the resistance of the organic photoconductor 10 in the irradiated part is lowered, and the charge in this part flows to the ground, and the surface potential approaches 0V. An electrostatic latent image is formed. In the reversal development method in which toner adheres to the electrostatic latent image and development is performed, a negatively chargeable toner is used as the toner.
Therefore, when the developing roller 11 having a thin layer of toner 5 negatively charged on its surface and the photosensitive drum 9 are rotated in opposite directions, the elastic force of the developing roller 11 causes the thin layer to become a photosensitive member 1.
It is slid on 0. The toner 5 adheres to the electrostatic latent image by the mechanical conveyance force and the electrostatic attraction force of the charges on the photoconductor and the charges of the toner, and the development is performed. On the other hand, although not shown, the main body 1 is provided with a paper supply tray for supplying paper. The paper supplied from this tray is sent between the photosensitive drum 9 and the transfer device 21 as a transfer material for transferring the toner image formed by development. When an electric charge having the same sign as that of the toner is applied to the back side of the fed paper by the transfer device, the toner image moves onto the paper by the force of the electric field. Further, while being supplied to the developing roller 11, it is not used for development, and the residual toner 5 is recovered again into the developing device through the recovery blade 19.

The developer of this embodiment accommodated in the above-described developing device is 94 parts by weight of polyester resin as a binder resin (binder resin) and carbon black (MA-100: manufactured by Mitsubishi Kasei Co., Ltd.) as a colorant. ) 3 parts by weight,
Toner composed of, for example, 1 part by weight of a chromium dye (S-34: manufactured by Orient Chemical Co., Ltd.) as a charge control agent and 2 parts by weight of wax (Viscole 660P: manufactured by Sanyo Kasei Co., Ltd.) as a release agent, silica as an external additive. 0.5 parts by weight of fine particles (R-972: manufactured by Nippon Aerosil Co., Ltd.) were mixed and externally added.

Next, a method of manufacturing the developer of the present embodiment having the above structure will be described. Examples 1 and 2 First, 94 parts by weight of a polyester resin as a binder resin, 3 parts by weight of carbon black (MA-100: manufactured by Mitsubishi Kasei) as a colorant, and a chrome dye (S-3 as a charge control agent).
4 parts by weight of Orient Chemical Co., Ltd. and 2 parts by weight of wax (Viscole 660P: manufactured by Sanyo Kasei Co., Ltd.) as a release agent are prepared. These are melt-kneaded using a continuous kneader or the like. Next, the product obtained by kneading is cooled and then pulverized and classified, and the volume average particle diameter is 5% or less in number%, 16
A developer having a volume% of not less than μm, a standard deviation of the number distribution of particle diameters, and a standard deviation of the volume distribution of particle diameters was obtained.

Such particles can be obtained by appropriately adjusting the crushing pressure and the air volume during crushing / classification. The particle size was measured using a Coulter counter (Coulter Electronics Co., Ltd.), which is a particle size meter that amplifies the electric resistance value generated when particles suspended in an electrolytic solution pass through pores. The measurement was carried out by cutting one channel (2 μm or less) as a measure against noise. To 100 parts by weight of this toner, silica fine particles (R-972:
0.5 parts by weight (produced by Nippon Aerosil Co., Ltd.) were mixed and externally added to obtain a toner.

[0027]

[Table 1]

These developers were evaluated, and the evaluation results are shown in Table 2. The evaluation methods are as follows. Fog on image This is the difference between the reflectance of the white part of the image and the reflectance of the untransferred paper. The smaller the value, the smaller the fog.

Fog on Drum: The value obtained by taking the difference between the reflectance of what was attached to the backing by taping the white background on the drum after development with a transparent tape, and the reflectance of what was attached to the backing with transparent tape, The smaller the number, the smaller the fog. A colorimeter CR100 manufactured by Minolta was used to measure the reflectance.

Image Roughness A halftone image was formed using a developer, and this image was visually evaluated. As a result of the evaluation, when it is non-uniform, it is indicated by x, and when it is uniform, it is indicated by o.

[0031]

[Table 2]

Table 1 shows the image quality of the developer obtained by changing the particle size distribution (fog on the image, fog on the photoconductor (drum),
The results of evaluation of (image roughness) at the initial stage and after the life of 20,000 sheets are shown.

[0033]

When an image is formed by using the non-magnetic one-component developer of the present invention, the image is not fogged on the electrostatic latent image carrier and the image and the image is not roughened even when the image is repeatedly formed. High quality images can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a developing device to which a developer of the present invention can be applied.

[Explanation of reference numerals] 1 ... Developing device main body 3 ... Container 5 ... Non-magnetic toner (developer) 7 ... Mixer 8 ... Rotating base 9 ... Photosensitive drum 10 ... Organic photoconductor 11 ... Developing roller 13 ... Toner supply roller 15 ... Blade 19 ... Recovery blade 21 ... Transfer device

Claims (2)

[Claims] 1. A volume average particle size of 7.0 to 12.0 μm,
Particles with a particle size of 5 μm or less 13.0 Number% or less, particle size 1
Particles of 6 μm or more 2.0% by volume or less, standard deviation of volume particle size distribution 2.7 or less, non-magnetic one-component developer. 2. A volume average particle diameter contained in a developer container.
Particles having a particle size of 7.0 to 12.0 μm and a particle size of 5 μm or less 13.
0% by number or less, particles having a particle size of 16 μm or more 2.0% by volume or less, and a standard deviation of the volume particle size distribution of 2.7 or less, a non-magnetic one-component developer is supplied to a developing roller. Linear pressure of 40-100g /
developer thin layer forming step of forming a thin layer of the developer on the surface of the developing roller by using a developer layer regulating blade pressed by cm, and an electrostatic latent image carrier provided facing the developing roller. And a developing step of developing the electrostatic latent image by supplying the developer to the electrostatic latent image.