JPH01285981A - Electrophotographic copying method - Google Patents

Abstract

PURPOSE:To attain a good cleaning effect even in the long period of use by controlling the toner concentration TC of cleaner, which is used by magnetic brush cleaning, to be 0.2-3.0wt.%. CONSTITUTION:Remaining toner is attracted electrostatically to the cleaner, and moved together with the cleaner from a drawing roller 72 to a drawing roller 73. After the remaining toner is moved from the drawing roller 73 to a recovery roller 74, the cleaner is scraped away by a cleaning scraper 75 in contact with the drawing roller 73, and is again returned to the surface of a cleaning roller 71. The remaining toner can easily be moved to the cleaner side and the toner can be smoothly moved to the recovery roller 74 by control ling the TC of the cleaner which is used in a cleaning part 7 to be 0.2-3.0wt.%. Hereby the cleaning of a photosensitive body 1 can be performed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic copying method in which toner remaining on the surface of a photoreceptor is removed by a magnetic brush cleaning method.

[Prior art]

As shown in FIG. 1, an electrophotographic copying apparatus generally includes a charger 2 around an organic or inorganic photoreceptor l (this is not limited to a drum shape but may also be a belt shape).
．． It is composed of an optical system 3, a developing section 4, a transfer charger 51, a separation charger 6, and a cleaning section 7. The transfer charger 5 is used to transfer the toner image on the photoconductor to a transfer paper 8 such as a toner paper, and the separation charger 6 transfers the toner image on the photoconductor 1.
It is used to separate it from the surface. In the drawings, numeral 9 indicates a separation claw.

By the way, either a dry development method or a wet development method (≠ dry development method included) is used to visualize an electrostatic charge image, but the former is advantageous in terms of obtaining copies in a dry state. Therefore, the dry developing method is currently the mainstream.

Dry development method uses a one-component developer (consisting only of toner)
It is broadly classified into two-component developers (consisting of carrier and toner). In any case, it is ideal that the 1-toner image visualized by such a developer is transferred to the transfer paper, but in reality, the toner that was not completely transferred to the photoreceptor remains. Therefore, this residual toner must be removed by a cleaning device.

Generally, methods for cleaning residual toner (untransferred toner) include (1) a fur brush, (2) a blade, and (3) a magnetic brush. However, the fur brush method requires a large cleaning device and tends to cause filming on the photoreceptor2, and the blade method has drawbacks such as being more likely to damage the photoreceptor. In contrast, cleaning using a magnetic brush method has been studied, for example, in Japanese Patent Application Laid-Open No. 102273/1984, but although the deficiencies of (1) and (2) above are eliminated, the conventional magnetic brush cleaning device This has the disadvantage that good leaning over a long period of time is not guaranteed.

〔the purpose〕

The object of the present invention is to provide a magnetic brush cleaning method that includes:
An object of the present invention is to provide an electrophotographic copying method that can produce a good leaning effect even after long-term use.

〔composition〕

In the present invention, an electrostatic charge image is formed on a photoreceptor.

In an electrophotographic copying method in which the toner is visualized using a charged toner, such as a two-component developer, and the toner image is transferred to transfer paper, the 1-toner remaining on the surface of the photoreceptor is removed by a magnetic brush cleaning section. The toner concentration of the cleaning agent used for magnetic brush cleaning is 0.
．． It is characterized in that it is controlled to 2 to 3°0 νt%, preferably 1 to 2 νt%.

If there is no toner in the cleaning agent (1-toner concentration TC=
(0%) The fluidity of the cleaning agent in the developing section is poor, making it impossible to uniformly supply the cleaning agent in the axial direction of the roller on the sleeve of the cleaning roller 71. In particular, if the carrier shape is an irregular type, the surface is uneven, so the fluidity is extremely poor.For 1"C0%, the saturation magnetization σS is large, so the driving torque of the developing section is increased. As a result, the torque of the entire machine increases, which is undesirable.

When the cleaning agent contains toner, even an amorphous type of carrier has good fluidity.

This is thought to be due to the toner acting as a lubricant. On the other hand, when TC is 3% or more, toner becomes difficult to transfer to the collection roller 74. In this case, the bias effect of the collection roller 74 will not be sufficiently effective. Therefore, when the bias is increased, not only the toner but also the carrier is transferred to the collection roller 74, and the cleaning agent becomes insufficient, and the supply of cleaning agent to the cleaning roller 7 becomes insufficient, gradually causing poor cleaning. Put it away.

In the following, the invention will be explained in more detail in the context of a copying process, with reference to the accompanying drawing (FIG. 1).

First, the surface of the photoreceptor (inorganic photoreceptor, organic photoreceptor) 1 is uniformly charged positively or negatively by the charger 2 . Whether the photoreceptor is positively charged or negatively charged is selected depending on the type (property) of the photoreceptor 1. For example, if the photoreceptor is Se-based, it will be positively charged. Image exposure is performed on this by the optical system 3 to form an fP charge image, and this electrostatic charge image is visualized in the developing section 4.

The developing section 4 stores a two-component developer consisting of a carrier (magnetic carrier) and a toner (development toner).

The developer is held on the developing sleeve 4 which has a built-in magnet 411 and develops the electrostatic charge image on the photoreceptor 1. Only the developed toner is consumed each time development is performed, so the toner concentration of the developer is determined by the sensor 42. New developing toner is supplied so that the i-toner density is always constant upon detection. 43 is a paddle wheel for stirring the developer. Note that a bias may be applied to the developing sleeve 41 if necessary.

The visible image (toner image) is transferred to the transfer paper 8 by the transfer charger 5.
The transfer paper 8 is separated from the photoreceptor 1 by the separation charger 6 and the separation claw 9 and sent to the fixing process.

As mentioned above, all of the toner forming a visible image on the photoreceptor 1 during transfer is not transferred to the transfer paper 8, and a portion remains on the photoreceptor. Then, a means is adopted in which this residual toner is removed by a cleaning section 7.

The cleaning section 7 in the present invention employs a magnetic brush cleaning method, and contains a magnetic carrier (cleaning carrier) as a cleaning agent. A bias of about 100 to 500 V of positive or negative polarity is applied to the cleaning roller 71 which has a built-in magnet (not shown), and the cleaning agent is held on the cleaning roller 7 by the magnet.

Here, the polarity of the bias applied to the cleaning roller 71 is opposite to the polarity of the toner in the two-component developer.

The remaining 1-toner is electrostatically attracted to the cleaning agent (cleaning carrier) and transferred together with the cleaning agent to the pumping rollers 72 to 73.
A residual toner collection roller 74 to which a bias of the same polarity as that of the cleaning roller 71 is applied is arranged behind the cleaning roller 71, and only residual toner is transferred to this collection roller 74.
Ru. The bias applied to the collection roller 74 is preferably relatively higher than the bias applied to the cleaning roller, preferably 200 to 800 V.
Immediately after the toner is drawn up and transferred from the pick-up roller 73 to the collection roller 74, it is scraped off by the cleaning souffle lever 75 that is in contact with the draw-up roller 73, and returned to the surface of the cleaning roller 71 again. On the other hand, the residual toner transferred to the collection roller 7.1 is scraped off by the collection plate 76 in contact with the collection roller 74, and taken out of the cleaning section 7 by the discharge screw 77. Used as a developer toner. Recovery play 1-76
The collection roller 74 that has been cleaned is used for the next collection of residual toner. Note that the cleaning agent (cleaning carrier) that falls onto the cleaning roller 71 and is circulated so as to contribute to the recovery of the residual toner again has the function of keeping the toner concentration at an appropriate value by getting the residual toner into the cleaning agent (cleaning carrier). do.

In the present invention, such a series of cycles of copying steps and cleaning steps are repeated, but when the photoreceptor 1 is uniformly charged by the 1f electric charger 2, there is no residual toner on the surface of the photoreceptor. Therefore, uniform charging of the photoreceptor 1 is guaranteed.

The cleaning agent used in the cleaning section 7 has a TC of 0.2 to 3.01 t%. By doing so, the residual 1-toner can easily be transferred to the cleaning agent (cleaning carrier) side, and the toner can be smoothly transferred to the collection roller 74.

Therefore, the photoreceptor 1 can be cleaned well.

Since the toner is smoothly removed by the collection roller 74, the toner concentration of the cleaning agent does not increase and remains constant. On the other hand, TC is 0.2wt%
If it is below, the flow of the cleaning agent is not good, and the cleaning agent cannot be uniformly supplied in the axial direction of the roller on the sleeve of the cleaning roller 71, resulting in a cleaning failure. When TC exceeds 3 wt%, toner becomes difficult to transfer to the collection roller 74. At this time, if the bias of the collection roller 74 is increased, not only the toner but also the carrier will be transferred to the collection roller 74, and the cleaning agent will disappear from the cleaning section, resulting in poor cleaning.

FIG. 2 shows another embodiment of the invention,
The composition of the cleaning agent of the present invention is as follows.

The residual toner on the photoreceptor 1 moves onto the cleaning roller 71 which is biased, and then moves to the collecting roller rough 4 at the rear (which is biased k).
The toner at No. 4 is scraped off by play 1-7G, and the toner moves to the discharge screw 77.

As a carrier core material, the average particle size is 20 to 1000μ,
Preferably 50-500μ sand, Kohar 1-1 iron, copper,
Conventionally used materials such as nonmetals such as nickel, zinc, aluminum, brass, and glass, metals, and metal alloys are widely used. In addition, for the coating θ, a resin may be dissolved in a solvent and applied to the surface of the core material by a conventionally known means such as a spraying method.9 Next, as a mold release resin for coating, a polyolefin resin may be used. , such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polyvinyl and polyvinylidene resins, such as Boristine L/N, acrylic resins (such as polymethyl methacrylate-1-1), polyacryloni-1-lyl, and polyvinyl acetate. 1-, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; enameled vinyl-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin consisting of organosiloxane bonds, etc. Silicone resins or modified products thereof (e.g. modified products with alkyd resins, polyesters, epoxy resins, polyurethanes, etc.); Fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride,
Examples include polychloro-1 to trifluoroethylene; polyamide; polyester, such as polyethylene terephthalate; polyurethane; polycarbonate-1; amino resin, such as urea-formaldehyde resin; and epoxy resin. Among them, acrylic resins, silicone resins or modified products thereof, and fluororesins, particularly silicone resins or modified products thereof, are preferred from the viewpoint of preventing the spent toner from adhering to the carrier. Silicone resin (straight silicone resin)
Commercially available products include Shin-Etsu Chemical KR271 and KR255.
, KR25], 1~-5R2400 manufactured by Resilicon
, 5R2406, etc., and modified silicone resins include Shin-Etsu Chemical's KR206 (alxodo resin modified product),
R3093 (acrylic + 5I lipid modified product), lEs
10 old N (epoxy resin modified product), Toren Recon 5R2115 (epoxy resin '!S' product), SR2
] 10 (alkyne 1-dendritic product), etc. The thickness of the coating layer may be approximately O11 to 2.5μ. Further, if necessary, a pigment such as phthalocyanine, a quaternary ammonium salt, silica, a dye, a resin, etc. may be added as a conductive substance or a charging material.

As the conductive carbon, any carbon blank that has conductivity can be used, such as furnace black (
As a commercially available product, B 1ack Pe made by Gearbok 1 Co., Ltd.
arls2000, Carbolacl; Lion Akzo's Ketchien Black EC-DJ500, Ketchien Black EC-D, J600, etc.), acetylene black (commercially available products are Denka Blank Granular, Denka Black Powder, made by Denki Kagaku Kogyo Co., Ltd.; Bostman) Company-made A
There are nacarbon etc. ) etc. Particle size is 0.5-500Iflμ, preferably 1-100I11
Approximately μ is appropriate.

On the other hand, as white conductive agents, TiO2, SnO2, Z
nO, etc., and mixtures thereof. Particle size is 0
．． 01-3μm, preferably 0.05-2.0μff1
The degree is appropriate.

Commercially available white conductive agents such as F are listed below. All percentages are by weight. Titanium Kogyo products: Ishihara Sangyo products: soow <titanium oxide-i oxide mixed system) 300W (
Titanium oxide-tin oxide mixed system) S-1 (Titanium oxide) Mitsubishi Metals product: Hakusui Chemicals product: 23K (oxidized surface g) Honjo Chemicals product Bi-conductive zinc white '4a] (Zinc oxide content 1) 9%)
Conductive zinc white No. 2 (zinc oxide content 99') 1
- As a specific example of controlling the toner concentration, developer is generally flowed through a coil wound around a cylinder, the change in frequency is detected, and when the frequency becomes lower than the predetermined frequency, 1-toner is replenished. In addition, there is a control method that skips toner supply when the frequency becomes higher than a preset value, and a control method that develops a reference pattern and determines whether the image density of that pattern is higher or lower than the standard. control method to turn on and off toner replenishment, and to turn on toner replenishment by comparing the developer reflection density with the reference value.
, OFF method, etc. can be used.

Figure 3 below shows a toner density sensor 4 in the cleaning section 7.
This is an example in which 2 is provided.

As shown in FIG. 3, a sensor 42 is provided to constantly control the toner density. The more desirable toner concentration is 1-2%.
Good. When the i-toner concentration is 0.2% to 15%, the probability of contact between the rear and the carrier increases, and especially when a coating layer is provided on the carrier core material, the film is scraped off very quickly, and the spent toner adheres to the carrier, causing the carrier to deteriorate. The charging ability of the battery is completely lost. Furthermore, the scraped material impedes the charging characteristics, resulting in no charge being generated at all.

As described above, each time cleaning is performed, toner is added to the cleaning section 7 and the toner collection roller 74
The toner is removed. At this time, the amount of toner added and the amount of toner removed (income and expenditure) are not always constant, so as shown in Figure 3, cleaning agent was flowed through the frequency detection sensor 42, and it was detected that the frequency was higher than the set value. Then, by replenishing toner from a toner replenishing section (not shown) and stopping toner replenishment when the frequency becomes lower than the set frequency, the toner concentration in the cleaning section 7 can be controlled to be constant at all times, and the toner concentration can be lowered. This eliminates problems caused by scraping of the carrier, and also prevents the bias effect of the cleaning section from disappearing due to an increase in toner concentration.

In the example, an average particle diameter of about 100 μm was used as a carrier for a component-based developer.
steel beads (Micro Shosso 1 to 5 manufactured by Shinto Brator Co., Ltd.)
F-100) was prepared.

On the other hand, a mixture of the following formulation was kneaded under heat on two rolls, cooled, and then pulverized and classified to produce a toner for a two-component developer having a particle size of 5 to 20 μm.

Polystyrene (Esso D-125)
l0RI (carbon blank (Mitsubishi Kasei 344)
100 parts of these carriers and 3. toner.
A two-component developer was prepared by mixing 0 parts. In addition, the amount of charge of 1-ner in this developer by the blow-off method (
Q/M) was -24 μc/g.

On the other hand, the cleaning carrier was coated with the following formulation.

A coating layer forming solution was prepared by dispersing a mixture of 1,500 parts of 1Helene in a homomixer for 30 minutes, and this was poured onto the surface of 5,000 parts of amorphous iron powder (TEFV 200/300) with a particle size distribution of 446-76p. A coating layer was formed in a thickness of about 0.9 μm using a bed-type coating device, and a carrier for cleaning was obtained.

A starter cleaning agent was prepared by mixing 100 parts of these carriers with varying amounts of the toner.

This agent was set in the cleaning unit shown in Figure 3, and a running test was conducted under the conditions shown below while controlling each toner concentration.The two-component developer and cleaning agent are shown in Figure 3. A copying machine (a selenium-based photoreceptor is used as the photoreceptor, the surface potential of the photoreceptor 1 is uniformly charged to +800 to 1, and the cleaning roller 7 is biased at +250!).
A bias of +300V was applied to the collection roller 74)
was set to obtain copies at a rate of 30 sheets per minute, and the toner consumed in the developing section 4 was replenished. The results of this running test 1~ are shown in Table 1.

Table-” l) Measured with a Macbeth densitometer (R5]4).

2) O indicates no dirt.

× indicates that there is dirt.

From Table 1, TC is 0.2 to 3. It can be seen that good results can be obtained when the ratio is □wt%. On the other hand, if 'rC is out of the above range, the cleaning properties will be poor and the image density will be low.Example 2 As a carrier for two-component developer, the average particle diameter is about 100μ.
n1 steel piece (Micro Shosso + manufactured by Shinto Blakey Co., Ltd.
-5F-+oo) was prepared.

On the other hand, a mixture of the following formulation was kneaded under heat on two rolls, cooled, and then pulverized and classified to produce a toner for a two-component developer having a particle size of 5 to 20 μm.

Polystyrene (Esso D-12,5)
100 parts carbon black (Mitsubishi Kasei #44)
10 parts of these carriers 10 (1 part and toner 3
．． A two-component developer was prepared by mixing 0 parts. Note 2: The amount of charge of the toner in this developer by the blow-off method (
Q/M) was -2.1 μc/g3 On the other hand, the cleaning carrier was coated with the following formulation, Ketchen Black ECDJ600.
5 parts toluene 15
00 parts was dispersed for 30 minutes using a homomixer to prepare a coating layer forming solution, which had a particle size distribution of 446-1.
6p irregular shaped iron powder (TEFν200/300) 5000
A coating layer was formed on the surface of the part to a thickness of about 0.9 μW using a fluidized bed type coating device, and a carrier for cleaning was obtained.

When this carrier was evaluated in the same manner as in Example 1, the same results as shown in Table 1 were obtained.

Example 3 The carrier of Example 1 (steel beads with an average particle diameter of about 100 μm) was prepared as a carrier for a two-component developer. On the other hand, a mixture of the following formulation was kneaded under heat on two roll mills, cooled, and then pulverized and classified to produce a toner for a two-component developer having a particle size of 5 to 20 μm.

Polystyrene (Esso D-125) 1
A two-component developer was prepared by mixing 100 parts of these carriers and 3.0 parts of 1-Chi. The Q/M in this developer was determined to be 20 μc/(4).

On the other hand, the cleaning carrier was coated according to the recipe in 1.

1-Luene 15
A coating layer forming liquid was prepared by dispersing the mixture consisting of 00 parts for 30 minutes in a homomixer, and this was mixed with a particle size distribution of 46-76.
μm irregular shaped iron powder (TEFν200/300) 500
A cleaning carrier was obtained by coating the surface of part 0 to a thickness of about 0.9 μm using a fluidized bed coating device to form a coating of 87 m.

When the same test as in Example 1 was conducted using this carrier, the same evaluation as in Example 1 was obtained.

Example 4 The carrier of Example 1 (steel beads with an average particle diameter of about 100 μm) was prepared as a carrier for a two-component developer6.Meanwhile, a mixture of the following formulation was kneaded under heat on two roll mills, and after cooling. The mixture was pulverized and classified to produce a two-component developer toner having a particle size of 5 to 20 μm.

Polystyrene (Esso D-125)
100 parts carbon blank (Mitsubishi Kasei #44)
10 parts of these carriers and 3 parts of toner
．． A two-component developer was prepared by mixing with 0 parts. The Q/M in this developer was measured to be -24 μc/g.

On the other hand, the cleaning carrier was coated as follows.

Ketchen Black ECDJ600
5 parts toluene 15
A coating layer forming liquid was prepared by dispersing the mixture consisting of 0.00 parts for 30 minutes in a homomixer, and the particle size distribution was 446-1.
6p irregular shaped iron powder (TEFV200/300) 5000
A coating layer was formed on the surface of the part to a thickness of about 0.9 μm using a fluidized bed type coating device to obtain a cleaning carrier.

Using this carrier, the same evaluation as in Example 1 was performed, and the same evaluation as in Example 1 was obtained.

〔effect〕

As is clear from the description of the examples, according to the copying method of the present invention, even when copying 100,000 sheets, there is no image stain and high quality copies can be obtained. Also.

After cleaning, the surface of the photoreceptor was visually observed to be extremely clean.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an electrophotographic copying apparatus used in the present invention, FIG. 2 is a modification of the cleaning section 7 shown in FIG. 1, and FIG. 3 is an example in which a toner concentration sensor is provided in the cleaning section. FIG. 1. Photoreceptor 2. Charger 3
・Optical system 4 Developing section 5 ・Transfer charger 6 ・Separation charger 7 ・・
Cleaning section 8...Transfer paper 9...Separation claw 41/Developing sleeve 411-magnetic
Stone 42, sensor 43, paddle wheel 71, cleaning roller 72.
73...Pumping roller 74-Recovery roller 75
・Cleaning souffle lever 76・・Recovery blade 7
7. Discharge screw patent applicant Rico Co., Ltd. −

Claims (1)

[Claims] 1. An electronic system that forms an electrostatic charge image on a photoreceptor, visualizes it with charged toner, transfers this toner image to transfer paper, and then removes the toner remaining on the surface of the photoreceptor using a magnetic brush cleaning section. An electrophotographic copying method characterized in that the toner concentration of a cleaning agent used for magnetic brush cleaning is controlled to be 0.2 to 3.0 wt%.