JP2001350285A - Method for nonmagnetic single component development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for nonmagnetic single-component development in the electrophotographic method such that melt sticking or deposition of the toner on a regulating blade is prevented and high quality images without fog or image defects can be obtained. SOLUTION: The method for nonmagnetic single component development is carried out by using a developer containing a toner which comprises at least a binder resin and a coloring agent and has >=95 deg.C and <=120 deg.C softening point and by using a developing device equipped with a developing roll and a conductive regulating blade to uniformly control the thin layer of the toner formed on the developing roll and to impart charges to the toner. In this method, toner particles having <=5 μm particle size of the developer are included by <=10% in the number of pieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing system using a non-magnetic one-component developer used for an image forming apparatus using a so-called electrophotographic method, such as an electrostatic copying machine or a laser beam printer. More specifically, the present invention relates to a non-magnetic one-component developing system in which a toner image is visualized on a photoconductor while a photoconductor and a developing roller are in contact with each other.

[0002]

2. Description of the Related Art Conventionally, electrophotography is disclosed in, for example, US Pat.
No.297691, No.42-23910, No.4
As described in JP-A-3-24748 or the like, generally, a charging process for uniformly charging a photoconductor containing a photoconductive substance, and an exposure for forming an electrostatic latent image by exposing the surface of the photoconductor. Process, a developing process of visualizing the electrostatic latent image on the photoreceptor surface into a toner image, a transfer process of transferring the toner image carried on the photoreceptor surface to the surface of the paper, and means such as heating and pressing. It comprises a fixing process for fixing the toner image on the paper.

[0003] Of these, in the development process, a two-component development system using a developer comprising a toner and a carrier and a one-component development system using a developer without a carrier are generally known. In recent years, maintainability, miniaturization, weight reduction,
Due to advantages such as cost reduction, the one-component developing system has been widely used. However, at present, there are still many problems to be improved in the one-component developing system. As a one-component developing method, a developing roller disposed in proximity to or in contact with the photoconductor, a supply roller for supplying toner to the developing roller, and a thin layer of toner on the developing roller in contact with the developing roller to apply electric charge A one-component developing system provided with a regulating blade is known.

[0004] In order to perform appropriate development on a photoreceptor by this one-component development system, it is very important to always form a stable thin layer of toner on a developing roller. In recent years, as colorization and fixing temperature have been lowered (energy saving), toner having a low softening point has been generally used. In the above-described non-magnetic one-component developing method, since the binder resin used particularly for full-color toner has such a low softening point, problems such as fusion and fixation of the toner to the regulating blade compared to the black toner are often cited. Can be When such fusing or sticking occurs, a thin layer is not uniformly formed on the developing roller, white streaks and the like are generated on the image, and further, electric charge is not sufficiently applied to the toner. This causes problems such as toner scattering in the machine.

To solve the above-mentioned problem, Japanese Patent Laid-Open No. Hei 8-221
In No. 38, 5 μm or less in the particle size distribution
It is described that the linear pressure of the regulating blade with respect to the developing roller is set to 40 to 100 g / cm or less, and a high-quality image without fogging or image deterioration can be formed for a long period of time. However, there is no description on the effect of preventing the toner from being fused and fixed to the regulating blade, the softening point of the toner is not limited, and no solution to the problem caused by the softening point is considered.

[0006]

SUMMARY OF THE INVENTION In the present invention, a long-term running of a non-magnetic one-component developing system stably deposits a thin layer of toner on a developing roller.
To provide a non-magnetic one-component developing method in electrophotography in which a high-quality image free of fog and image defects can be obtained without deterioration of the toner, no fusion of the toner to the regulating blade, and no occurrence of fixation. Aim.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, using a non-magnetic one-component developer having a softening point of 95 ° C. or more and 120 ° C. or less as a developer, The present invention has been completed in which fusion and sticking to the regulating blade hardly occur. That is, the non-magnetic one-component developing method of the present invention is a toner comprising at least a binder resin and a colorant, the developer having a softening point of 95 ° C. or more and 120 ° C. or less, a developing roller, In non-magnetic one-component development using a developing device provided with a conductive regulating blade for uniformly regulating a thin layer of the toner formed on a developing roller and imparting charge to the toner, the developer particles having a size of 5 μm or less Is 10
The present invention relates to a non-magnetic one-component developing system characterized by being at most a few percent.

In the developing roller of the present invention, the conductive regulating blade has a linear pressure of 15 gf / cm or more and 50 g or more.
Pressing at f / cm or less is desirable for forming a stable thin layer during long-term running.

In the above-mentioned developing method of the present invention, the developing roller has a Asker C hardness of 50 ° or more and 85 ° or less on the surface of the developing roller. This is desirable because a high quality image can be obtained. Further, the developer in the present invention is a toner for forming a full-color image, and the binder resin of the toner is preferably a polyester resin.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. First, the developer used in the present invention is a non-magnetic one-component developer toner not using a carrier comprising at least a binder resin and a colorant,
The toner has a softening point of 95 ° C. or more and 120 ° C. or less, and 10% by number or less of 5 μm or less of the developer particles which easily adhere to the regulating blade. In this case, the developer contains at least 1 to 30 parts by weight, preferably 2 to 20 parts by weight, of the colorant based on 100 parts by weight of the binder resin, and also appropriately contains a charge control agent, wax and the like.

The toner having a softening point of 95 ° C. or more and 120 ° C. or less has a softening point of 95 to 12 as a binder resin.
It is adjusted by using a material having a relatively low molecular weight around 0 ° C., or by using a wax having a low melting point as an additive even when the softening point is 120 ° C. or more.

Further, the regulation of the amount of toner particles having a particle size of 5 μm or less which easily adheres to the regulating blade is adjusted together with the particle size distribution by cutting (classifying) the fine powder of the pulverized toner when producing the toner by a pulverization method. . In this case, although it depends on the capacity of the classifier, it is better to reduce the amount of fine powder to be cut in consideration of productivity (yield), cost, and the like. In addition,
If there is no problem in productivity, cost, and the like, it is desirable in the present invention that the number of developer particles of 5 μm or less be 10% by number or less, more preferably 8% by number or less, since the effect of further extending the life can be obtained.

The toner particle diameter of the developer of the present invention is not particularly limited as long as it satisfies the above-mentioned conditions, and a toner having a volume average particle diameter of 3 to 12 μm is used. In order to obtain a high quality image, a small particle size toner having a volume average particle size of 9 μm or less is preferable. The volume average particle diameter of such a small particle diameter toner is particularly preferably 4 to 9 μm, and more preferably 5 to 8 μm, within the above range in consideration of improvement in image quality.

However, the constitution of the present invention can be applied to ordinary electrophotographic toners other than the above-mentioned small particle size.
In this case, the toner particle size of the developer may be equal to or more than the above range. Here, the toner particle size (particle size distribution) is generally measured by an electrolytic solution method or a measuring device utilizing the principle of laser diffraction.

Next, a non-magnetic one-component developing system using the above-described developer of the present invention will be described in detail with reference to the accompanying drawings. The non-magnetic one-component developing system of the present invention can be used in a non-magnetic one-component developing apparatus as shown in a schematic sectional view in FIG. Here, the developing device is a container in which the developer used in the present invention is supplied and stored,
The toner stirring blade 4, the developer supply roller 3, the rotating developing roller 1, the conductive regulating blade 2 pressed by linear pressure against the developing roller 1, and the photosensitive member 5 which is opposed to (or in contact with) the developing roller 1 It is composed of combinations.

In FIG. 1, the developer supplied from the supply roller 3 to the developing roller 1 is frictionally charged by being pressed against the rotating developing roller 1 by the linear pressure of the conductive regulating blade 2. The developer is uniformly regulated on the surface of the developing roller 1 and adheres as a uniform thin layer. Next, the developing roller 1
A uniform thin layer of the developer is adhered to the electrostatic latent image on the photoreceptor 5 provided to be opposed to or in contact with the surface, and the electrostatic latent image is visualized as a toner image.

Here, the electrostatic latent image on the photosensitive drum 5 is uniformly charged in advance on a photosensitive member containing a photoconductive substance by a charger (not shown), and the original image is converted into an optical signal by a laser (not shown). Upon irradiation (exposure), the resistance of the photoreceptor in the exposed portion decreases, and the charge in this portion flows to the ground, the surface potential approaches 0 V, and the electrostatic latent image is visualized. The toner image adhered on the photoreceptor 5 is transferred to the surface of the sheet by a transfer unit (not shown), and then the toner image is fixed on the sheet by means such as heating and pressing.

Here, in the non-magnetic one-component developing system as shown in FIG. 1, as a characteristic of the toner in the developer, generally, the finer the particles, the higher the adhesive force to the regulating blade. Therefore, a toner having a small particle diameter of 5 μm or less, for example, selectively adheres to the regulating blade, and the adhered toner is easily fused and fixed to the regulating blade by frictional heat. In particular, the lower the softening point of the toner, which is disadvantageous to the friction resistance (heat resistance), the easier it is to fuse and adhere to the regulating blade.

In the present invention, as described above, a developer having a relatively low softening point of 95.degree. C. to 120.degree. C. is used, and the toner fine particles of 5 .mu.m or less in the developer are used.
By setting the content to 0% by number or less, more preferably 8% by number or less, the fusion and fixation of the toner to the regulating blade can be suppressed,
By forming a stable toner thin layer even during long-term running, a high-quality image free from fogging and image defects can be obtained.

Further, in the present invention, in the non-magnetic one-component developing system using the developer toner, particularly, the linear pressure of the conductive regulating blade 2 with respect to the developing roller 1 is set to 15 to
It is desirably 50 gf / cm, preferably 20 to 40 gf / cm. When the linear pressure of the regulating blade 2 is 15 gf
If it is less than / cm, a stable uniform thin layer of the developer cannot be formed. Conversely, if the linear pressure is higher than 50 gf / cm, the developer toner adheres to the regulating blade and fusing and stick to the regulating blade when running for a long time even if there is no problem initially.

The developing roller 1 adheres charged toner onto the electrostatic latent image on the photoreceptor 5 to visualize the electrostatic latent image into a toner image, and usually has conductivity and elasticity. It is covered by a member that also serves. In the case of a developing method in which the photosensitive member and the developing roller are in contact with each other, it is particularly preferable that the Asker C hardness of the developing roller is 50 ° or more and 85 ° or less. The Asker C hardness of the developing roller is 50
If it is less than 0 °, there is no particular problem at the beginning, but the developing roller may be deformed by distortion due to continuous use or standing for a long period of time. The Asker C hardness of the developing roller is 85.
When the angle exceeds °, an image defect occurs. That is, because the hardness of the developing roller is high, smooth rotation with the contacting photoconductor is not performed (banding occurs), and density unevenness appears on the image as streaks.

As the member of the developing roller, urethane rubber, silicone rubber, NBR, EPDM, natural rubber and the like can be used. Of these materials, urethane rubber is difficult to use as a material for lowering the hardness, and silicon rubber can be used. However, silicon rubber has a large amount of residual silicon oil, and in the contact development method in which the developing roller is in direct contact with the photoconductor, this silicon oil contaminates the photoconductor, and there is a problem that the image in that portion becomes white. Well pointed out. Therefore, in the present invention, when the contact developing method is used, it is desirable that the Asker C hardness of the developing roller is at least 50 ° or more.

The toner supply roller 3 is covered with a member having elasticity in order to efficiently supply the toner onto the photosensitive drum 5. As such a member, a urethane sponge or the like can be used. The conductive regulation blade 1 can be made of SUS metal, aluminum plate, phosphor bronze, or the like. In the present invention, a so-called contact developing system in which the photosensitive drum 5 and the developing roller 1 are in surface contact with each other to form a toner image on the photosensitive member is preferable.
The use of a non-contact development system is also possible.

The binder resin that can be used in the developer toner of the present invention is used to integrate the materials to be blended. For example, polystyrene, polyp
-Chlorostyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic Acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, Styrene-phenyl acrylate copolymer),

Styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-octyl methacrylate copolymer, styrene Phenyl methacrylate copolymer),
Styrene resins (homopolymers or copolymers containing styrene or styrene substituents) such as styrene-α-methyl methyl acrylate copolymer, styrene-acrylonitrile acrylate copolymer, polyvinyl chloride,
Low molecular weight polyethylene, low molecular weight polypropylene, ethylene-ethyl acrylate copolymer, polyvinyl butyral, ethylene-vinyl acetate copolymer, rosin-modified maleic resin, phenolic resin, epoxy resin, polyester resin, ionomer resin, polygretan resin, silicone resin , Ketone resin, xylene resin, polyamide resin and the like. These may be used alone or in combination of two or more. Particularly, for a full-color toner, a polyester resin having a softening point of 95 ° C. or more and 120 ° C. or less is preferable from the viewpoint of thermal property control and the like.

As the colorant used together with the binder resin of the present invention, any pigment or dye commonly used in toners can be used. For example, carbon black, iron black, phthalocyanine blue, ultramarine, quinacridone, benzine yellow and the like can be mentioned. Among the coloring agents used in particular, for full-color image formation, pigments and dyes are used according to a desired color in three colors of yellow (Y), magenta (M), cyan (C) and four colors including black. Is done.

Here, as the colorant for the yellow (Y) toner, for example, C.I.
I. Pigment Yellow 1, CI Pigment Yellow 5,
Azo pigments such as CI Pigment Yellow 12, CI Pigment Yellow 15, and CI Pigment Yellow 17,
And inorganic pigments such as yellow iron oxide and loess.

Examples of the dye include nitro dyes such as CI Acid Yellow 1, CI Solvent Yellow 2, CI Solvent Yellow 6, CI Solvent Yellow 14, CI Solvent Yellow 15, CI Solvent Yellow 19, and CI Solvent Yellow 21. And other oil-soluble dyes. Among these, benzidine pigments such as CI Pigment Yellow 17 are particularly preferably used in terms of tint as a yellow colorant.

Examples of the colorant for magenta (M) toner include CI Pigment Red 49, CI Pigment Red 57, CI Pigment Red 81, CI Pigment Red 122, CI Solpent Red 19, CI Solpent Red 49, and CI Solpent. Tread 52, CI Basic Red 10, CI Disperse Red 15, and the like. Among them, particularly, quinacridone pigments such as CI Pigment Red 122 are suitably used in terms of color as a magenta colorant.

Examples of the colorant for cyan (C) toner include CI Pigment Blue 15 and CI Pigment Blue 1
6, CI Solpent Blue 55, CI Solpent Blue 70, CI Direct Left Blue 25, CI Direct Left Blue 86 and the like. Among them, particularly, a copper fugurocyanine pigment such as CI Pigment Blue 15 is suitably used in terms of a tint as a cyan colorant. Black is
Carbon black is preferably used.

The toner of the present invention may further contain a charge controlling agent for controlling the triboelectric charging property of the toner. The charge control agents include those for controlling positive charges and those for controlling negative charges according to the charging characteristics of the toner. Organic compounds having a basic nitrogen atom as a charge control agent for controlling positive charges,
Examples include basic dyes, quaternary ammonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine base and the like.

Examples of charge control agents for controlling negative charges include oil-soluble dyes such as oil black and spiron black, metal-containing azo dyes, metal salts of naphthenic acids, metal salts of alkyl salicylic acids, fatty acid salts, resin acid soaps and the like. Is mentioned. The amount of the charge control agent added to the toner is 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the binder resin. For colors, colorless quaternary ammonium salts and metal salts of alkyl salicylic acids are desirable. However, it is not always necessary.

The developer toner used in the developing system of the present invention includes the binder resin described above, a colorant and a charge control agent,
A mixture obtained by uniformly premixing additives such as wax by a dry blender, a super mixer, a ball mill, etc., is uniformly mixed using a kneading device such as a Banbury mixer, a roll, a single screw or twin screw extruder. After the melt-kneading, the obtained kneaded product is cooled, pulverized, and classified if necessary. An external additive such as silica fine powder is appropriately added to the obtained toner.

[0034]

Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited by these examples. In addition, the measuring method of each physical property value shown in the following Examples and Comparative Examples is as follows.

1) Measurement of softening point Sample size was measured using a flow tester (manufactured by Shimadzu Corporation).
0mg, die 1.0mm × 1.0mm, heating rate 6.0 ° C / m
The measurement was performed under the conditions of an in-load of 20 kgf / cm ² and the temperature (Tm or T1 / 2) at which the sample flowed out by １ ／ was defined as the softening point. 2) Measurement of particle size distribution The particle size distribution was measured using a Coulter Counter Multisizer II (manufactured by Coulter). The number of particles measured was 50,000.

3) Measurement of Image Density Image density was measured by X-rite 938 manufactured by X-rite. 4) PC fog measurement A transparent tape (Mending tape manufactured by Sumitomo 3M) was attached to the non-image area on the photoreceptor, and then attached to blank paper.
Measure the concentration by write938. Further, only the transparent tape was pasted on white paper in advance, the density was also measured, and the difference from the above density was defined as the PC fog value.

5) Confirmation of Fused Material on Control Blade The developing roller was removed, and the toner on the control blade was blown off with a blower. Thereafter, the surface of the control blade was checked using an optical microscope. In advance, the toner on the developing roller is sampled on a blank sheet of paper with a transparent tape, and the presence or absence of a white stripe or the like is confirmed. 6) Measurement of Attached Amount and Charge Amount on Developing Roller The counter charge when the toner on the developing roller was sucked by a suction method was measured, and the charge amount and the sucked weight of the toner were measured to obtain a specific charge. In addition, a transparent tape (Mending tape manufactured by Sumitomo 3M) is attached to the suction mark,
The area affixed on white paper and then sucked was determined, and the amount of adhesion per unit area was determined.

Examples 1 to 8 and Comparative Examples 1 to 6 <Production method of toner> 100 parts by weight of polyester, 5 parts by weight of colorant (copper phthalocyanine) and 2.0 parts by weight of charge control agent (zinc compound of salicylic acid) After uniform mixing with a super mixer, heat and melt and knead with a twin screw extruder,
Cool. The kneaded product thus obtained was roughly pulverized by a cutting mill, finely pulverized by an ultrasonic jet mill, and fine powder having a volume-converted particle size of 5 μm or less was removed by a classifier to obtain each toner. The particle size of the toner is 5 to 16 μm in terms of volume.
And the volume average particle size was 8.0 μm.

<Electrophotographic Recording Apparatus> The apparatus has the photoreceptor process and the developing apparatus shown in FIG. 1, and the applied voltage of the developing roller is -300 V, the applied voltage of the toner supply roller and the conductive regulating blade is -400 V, and the developing is performed. The peripheral speed ratio between the roller and the toner supply roller was 0.9, the peripheral speed ratio between the toner and the photoconductor was 1.5, and the process speed was 90 mm / sec.

[0040]

[Table 1]

<Actual photo test> The developing device of the AR-5030 manufactured by Sharp, which incorporates the above-mentioned electrophotographic recording device, was modified for a non-magnetic one component, and the linear pressure (gf / cm) of the conductive regulating blade in the developing device was used. The working conditions such as the hardness of the developing roller and the like were variously changed as shown in Table 1 to obtain Examples 1 to 8 and Comparative Examples 1 to 6. A continuous actual shooting test of 40,000 sheets was performed under a normal temperature and normal humidity environment. The amount of toner adhering to the developing roller and the specific charge, the image density, the PC fog, and the presence or absence of fusing were checked at the initial stage and after the actual test. Table 2 shows the results of Examples 1 to 8 of the present invention, and Table 3 shows the results of Comparative Examples 1 to 6. However, the fusion state on the regulating blade is ：: none
Δ: Partial ×: Displayed on almost the entire surface.

[0042]

[Table 2]

[0043]

[Table 3]

<Results of Examples and Comparative Examples> Examples 1 to 8
According to the results of the above, in the long-term actual shooting test, the fluctuation of the amount of the developer toner on the developing roller is small, and the toner does not fuse or adhere to the regulating blade, and a high-quality image without fog and image defects is obtained. Could be offered. In Comparative Examples 1 and 2, although there was no problem at first, white streaks occurred due to the adhesion of the toner to the regulating blade during the actual shooting test. In Comparative Example 3, since the softening point was low, the toner was fixed on almost the entire surface of the regulating blade, and poor charging and a significant decrease in image density were obtained. Comparative Example 4 had a high image density and fog because the amount of toner adhered to the developing roller was large from the beginning.
During the actual shooting test, toner scattering occurred in the machine. In Comparative Example 5, since the amount of toner adhered to the developing roller was small from the beginning, the solid portion was slightly blurred, the image density was low, and the toner adhered to almost the entire surface of the regulating blade even during the actual shooting test. In the image sample of Comparative Example 6, streaks due to density unevenness occurred. This is because banding has occurred between the developing roller and the photosensitive member in contact with the developing roller because the hardness of the developing roller is too high. Therefore, in the present invention, the linear pressure of the regulating blade is 15 gf / cm or more and 50 g / cm,
It is preferable that the Asker C hardness of the developing roller be 50 ° or more and 85 ° or less.

[0045]

According to the present invention, even during long-term running, the amount of the developer adhered on the developing roller is formed stably, and the toner does not fuse or adhere to the regulating blade, and the toner is adhered on the developing roller. By forming a stable thin layer of toner, it is possible to provide a high-quality image free from fogging and image defects.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a non-magnetic one-component developing device.

[Explanation of symbols]

 Reference Signs List 1 developing roller 2 regulating blade 3 developer supply roller 4 stirring blade 5 tourist object

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/08 507 G03G 15/08 507L (72) Inventor Tetsu Ogawa 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka No. Sharp Corporation F term (reference) 2H005 AA01 AA21 CA08 EA03 EA05 FA07 2H077 AD06 AD13 AD17 AE03 EA14 EA15 FA25

Claims (5)

[Claims] 1. A toner comprising at least a binder resin and a colorant, wherein the toner has a softening point of 95 ° C. or more and 120 ° C.
Using a developing device having the following developer, a developing device having a developing roller and a conductive regulating blade that uniformly regulates a thin layer of the toner formed on the developing roller and imparts a charge to the toner. A non-magnetic one-component developing system, wherein the number of toner particles of the developer of 5 μm or less is 10% by number or less in the magnetic one-component developing system. 2. The non-magnetic one-component developing system according to claim 1, wherein the conductive regulating blade is pressed against the developing roller at a linear pressure of 15 gf / cm or more and 50 gf / cm or less. 3. The non-magnetic one-component developing method according to claim 1, wherein the Asker C hardness of the developing roller is 50 ° or more and 85 ° or less. 4. The non-magnetic one-component developing method according to claim 1, wherein the toner is a color toner, and the binder resin of the toner is a polyester resin. 5. The non-magnetic one-component developing method according to claim 1, wherein the number of the developer toner particles of 5 μm or less is 8% by number or less.