JPS6087351A - Toner coating method - Google Patents

Abstract

PURPOSE:To form a thin layer of toner uniformly on the surface of a toner carrier, applying it by sufficient frictional electrostatic charging, and prevent the toner from leaking from a developing device by using magnetic particles which have specific fluidity. CONSTITUTION:A developer container 3 for the storage of toner 4 and magnetic particles 5, a sleeve 2 which carries the toner 4 to a photosensitive drum 1, and a magnet 7 which forms a magnetic brush of magnetic particles 5 contacting the sleeve 2 at the upstream side of the toner exit of the container 3 are arranged to form the thin layer of the toner 4 on the sleeve 2. In this case, magnetic particles 5 of about 10-50sec/g in fluidity are used. Consequently, the magnetic particles 5 circulate properly with proper restraint force generated by a magnetic field and the formed magnetic brush has proper hardness and density. Therefore, no stripe due to a deficiency in restraint is formed on the sleeve 2, and the coating layer on the photosensitive drum 1 need not be made extremely thin; and ghost, white absence, etc., are prevented as well as fogging, and a leak of the developer is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner application method for developing an electrostatic latent image with toner.

Conventionally, various types of dry-component developing devices have been proposed and put into practical use. However, in any of the development methods, it is extremely difficult to form a thin layer of dry component developer, and for this reason, a developing device has been constructed by forming a relatively thick layer.

However, as improvements in the sharpness, resolution, etc. of developed images are currently sought after, it is essential to develop a method for forming a thin layer of a dry-component developer and an apparatus therefor.

As a method of forming a thin layer of a conventionally known dry component developer, Japanese Patent Application Laid-Open No. 54-43037 has been proposed and has been put into practical use. However, this was related to the formation of a thin layer of magnetic developer.To make magnetic developer magnetic, it is necessary to add a magnetic substance to it, which is used to heat-fix the developed image transferred to transfer paper. poor adhesion when
Since the magnetic material is added to the developer itself, there are problems such as poor color reproduction during color reproduction.

For this reason, as a method for forming a thin layer of non-magnetic developer, there are two methods: using a soft cylindrical brush made of soft bristles such as Pevar o bristles, and applying the developer to the brush. A method has been proposed in which the film is applied to a developed roller using a doctor blade or the like. However, when an elastic blade is used as a doctor blade for the fiber brush mentioned above, although it is possible to control the amount of developer, uniform application is not achieved and the fiber brush on the developing roller is simply rubbed.
Since no triboelectric charge is imparted to the developer existing between the fibers of the brush, there is a problem in that ghosts and the like are generated. Furthermore, since the device includes a non-magnetic developer, it is difficult to prevent the developer from leaking from the device.

The present invention eliminates the problems of the conventional method described above, and provides a new toner application method in which the developer is formed as a uniform thin layer on the surface of a developer holding member, and is coated with sufficient triboelectric charging. The purpose is to A further object of the present invention is to prevent the developer from leaking out of the developing device.

The coating method of the present invention that achieves the above object includes a developer container that stores toner and magnetic particles for toner coating, a toner carrier that conveys the toner to a latent image carrier, and a toner outlet of the developer container. A toner coating method in which a thin layer of toner is formed on the toner carrier by disposing a magnet forming a magnetic brush made of toner coating magnetic particles in contact with the toner carrier on the upstream side. flow rate is 1
It is characterized by being 0 to 5o(8)15o2.

The latent image carrier of the present invention may be a drum-shaped or belt-shaped member having a photoconductor or an insulating layer, and the magnetic poles may be magnetized with magnetic poles of the same polarity or different polarity in the axial direction of a magnetic roller. Alternatively, a plurality of rod-shaped magnets bonded onto a fixed support member may be used. Furthermore, as the rotating developer holding member, it is possible to use a sleeve made of non-magnetic metal such as aluminum, copper-stainless steel, brass, etc. or a synthetic resin material, or an endless belt made of resin or metal. In order to improve the electrostatic properties and charging properties, the surface may be roughened or coated with a gold film having an uneven pattern. Further, as the regulating member provided on the outlet side of the developer container as required, a blade plate or wall made of a magnetic material such as iron or a non-magnetic material such as aluminum, copper, or resin may be used.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows a sectional view of a developing device for explaining the developing principle to which the coating method of the present invention is applied.

In the figure, reference numeral 1 denotes an electrophotographic photosensitive drum, which holds a latent image formed by a latent image forming means (not shown) and rotates in the direction of arrow a to pass through a developing position shown in the drawing. For the photoconductor drum l, a non-magnetic toner carrier that supports toner is used.

The sleeves 2 are opposed to each other with a predetermined gap maintained between them, and these sleeves 2 rotate in the direction indicated by the arrow.

A container 3 made of non-magnetic material such as resin or aluminum is located above the sleeve 2 and stores a mixture of toner 4 and magnetic particles 5. A magnetic blade 6 is screwed on.

On the other hand, a magnet 7 is provided on the opposite side of the sleeve 2 to the magnetic blade 6. The mounting position of this magnet is determined by the relationship between the position of the magnetic pole and the magnetic blade 6.
In fact, by providing a magnetic pole slightly upstream of the position of the magnetic blade 6, the effect of the magnetic field produces good results in terms of preventing the outflow of magnetic particles and uniformly applying toner.

In the above configuration, the magnetic particles 5 in the container 3 form a magnetic brush 8 due to the magnetic field generated between the S pole of the magnet 7 and the magnetic blade 6. Then, as the sleeve 2 rotates, the magnetic particles and toner are stirred and mixed while the magnetic brush 8 is held. In this state, on the magnetic blade side of the container 3, the mixture of magnetic particles and toner is prevented from moving by the blade 6 due to the presence of the blade 6, and moves upward, causing circulation in the direction of arrow C.

As a result, the toner is triboelectrically charged by the sleeve 2 or the magnetic particles by mixing with the magnetic particles. The charged toner is uniformly and thinly applied to the surface of the sleeve 2 by a mirror force by a magnetic brush 8 formed near the magnetic blade 6, and reaches a position facing the photoreceptor drum.

By the way, the magnetic particles 5 constituting the magnetic brush 8 do not flow onto the sleeve 2 by setting the restraining force due to the magnetic field of the magnet 7 to be larger than the conveying force caused by the frictional force. If there is toner within the area of the magnetic brush 8, the ratio of the magnetic particles of the magnetic brush 8 to this toner is
As the sleeve 2 rotates, it maintains an approximately constant value. Thereby, even if the toner on the sleeve is consumed during development, toner is automatically supplied to the area of the magnetic brush 8. Therefore, it is possible to always supply and apply a constant amount of toner onto the sleeve 2.

As is clear from the above description, magnetic particles are particularly important as components in the present invention. The above-mentioned magnetic particles perform the function that magnetic particles had as a carrier material used in two-component developers, which were mixed with the toner in a much larger amount than the toner. Rather than the function of controlling the amount of the band'JL, it is necessary to form a magnetic brush in a system where a large amount of toner exists, apply the toner onto the toner carrier, and also perform the function of regulating the amount. No. At the same time, it must also have the function of supplying toner while circulating, and furthermore, it is not preferable for the magnetic particles to pass through the regulating member. In order to satisfy these functions, the state of the magnetic brush must be such that it has an appropriate restraining force generated by the magnetic field, and also exhibits appropriate circulation.
It must have appropriate hardness and density to enable uniform application. For example, a comparatively thin brush tends to cause poorly controlled streaks on the toner carrier, and a brush that is densely packed tends to make the coating layer on the holding member extremely thin. None of them are desirable0
Furthermore, for example, if the circulation is too good, the coating layer becomes thick and capri is produced on the image, and if the circulation is poor, ghosts are likely to occur, and various other disadvantages may occur.

The present inventors studied seeding in order to satisfy the various functions required by the magnetic particles used in the present invention, and as a result, they found that the fluidity of the magnetic particles has a large influence.

For example, if the fluidity of the magnetic particles is poor, the circulation of the brush will be poor, resulting in defects such as the occurrence of ghosts or a decrease in density due to poor application amount (in some cases, some images may appear white), and the flow of the magnetic particles will occur. If the resistance is too good, problems such as the generation of capri, or leakage of magnetic particles passing through the regulating member may occur due to the circulation of the brush being too fast. Therefore, there is a preferable range for the fluidity of magnetic particles. The fluidity of the magnetic particles can be defined, for example, by measuring the fluidity as defined in JIS Z-2502.

In the present invention, a powder rheometer manufactured by the Institute of Production Development Science 9e is used for measurement according to the operating method specified in JIS Z-2502, and the flow rate is 10 to 50 seconds.
Magnetic particles exhibiting ec1509 can be preferably used, and a range of 10 to 40 see 1509 is more preferable. (The correction coefficient for correcting variations between models was determined to be 1.035 after measuring a standard sample specified by the manufacturer.) The magnetic particles for toner application used in the present invention include, for example, surface-oxidized or unoxidized iron. , nickel, cobalt,
Metals such as manganese, chromium, rare earth a, and alloys or oxides thereof can be used, and the surface thereof may be coated with a resin or a suitable treatment agent. Moreover, there are no special restrictions on the manufacturing method.

On the other hand, as the binder resin of the toner used in the present invention,
Monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene; styrene-P-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, Styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-acrylic-aminoacrylic copolymer, styrene-
Aminoacrylic copolymer, styrene-alpha chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer Styrenic copolymers such as styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; methyl methacrylate,
Polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic resin Hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin,
Paraffin wax and the like can be used alone or in combination.

Any suitable pigment or dye can be used as a colorant in the toner. For example, carbon black, iron black, phthalocyanine blue.

Known dyes and pigments include ultramarine, quinacridone, and benzidine yellow fx.

In addition, as a charge control agent, amine compounds, quaternary ammonium compounds, organic dyes, especially basic dyes and their salts,
Benzyl dimethyl-hexadecyl ammonium chloride, decyl-trimethyl ammonium chloride, nigrosine base, nigrosine hydrochloride, safranin γ and crystal violet, metal-containing dyes, salicylic acid metal-containing compounds, etc. may be added.

The toner composition described above may be used in a developer produced by a commonly used mixing-pulverization method, or may be used as a wall material, a core material, or both of them in a microcapsule developer.

The present invention will be explained in more detail with reference to Examples below. The parts given in the examples are parts by weight.

[Embodiment 1] In FIG. 2, the same members as in FIG. 1 are given the same reference numerals. In the embodiment apparatus, the photosensitive drum 1 rotates in the direction of arrow a at a circumferential speed of 60 questions/second. 2 is 6 in the direction of the arrow
Rotating at a circumferential speed of 6 tones/second, outer diameter 32 degrees, thickness 0.8.
The sleeve is made of 0.0 stainless steel (SU, 8304), and its surface is sandblasted using +-600 alundum abrasive grains, and the circumferential surface degree is 0.8 μm.
(Rz −).

On the other hand, a sintered ferrite type magnet 7 is fixedly disposed inside the rotating sleeve 2, and the N pole of the first magnetic pole is a line connecting the center O of the sleeve 2 and the tip of the blade with respect to the magnetic blade 6. It is set at an angle of 30 degrees (θ in the figure).

The magnetic blade 6 is made of iron, and its surface is nickel-plated to prevent rust. The distance between the blade 6 and the surface of the sleeve 2 was set to 200 μm.

The magnetic particles 5 have a particle size of 70 to 100μ and a fluidity of 14.
．． 100g of sponge iron powder of 8sec150f was used.

On the other hand, Toner 4 has an average particle size of 100 parts of polyester resin, 10 parts of copper phthalocyanine pigment, 5 parts of negative charge control material (alkyl salicylate metal complex), and 05% of silica added externally. 200 g of cyan powder charged with negative (-) polarity of 12 μm was prepared. After the toner and magnetic particles are thoroughly mixed, they are placed in the container 3. The mixture of toner and magnetic particles in the container 3 was observed to move in circulation as the magnetic particles were conveyed by the sleeve under the magnetic field, especially when the amount of developer was low. .

In the developing device having the above configuration, a thin layer of only toner having a thickness of about 40 μm was formed on the surface of the sleeve 20 as the IJ-spun rotated. When the charging potential of this developer layer was measured by the plow-off method, it was found to be -7.1 μc.
It was confirmed that the sample was charged uniformly at a potential of /g.

On the surface of the photosensitive drum 1 facing this sleeve 2, a charge pattern with a dark area of +600V and a bright area of 150V was formed as an electrostatic latent image, and the distance to the sleeve surface was set to 300μm. When a voltage with a frequency of 800 Hz, a peak-to-peak value of 1.4 KV, and a center value of +300 V was applied using power supply E, a high-quality clear blue developed image was obtained without uneven development, ghost images, or rainbow fog. I was able to get it.

Furthermore, regarding the mixture in container 3, only the toner was consumed for development, with almost no magnetic particles being consumed.

Further, the developing function remained unchanged until almost all of the toner was consumed. After the toner was consumed, the developing device was removed from the main body and the lower part of the sleeve 2 was looked at, and it was found that there were not only magnetic particles but also almost no toner leakage there.

[Example 2] The distance between the blade 6 and the sleeve 2 is 100μ, and the magnetic particles 5 are fluidized dust whose surfaces are coated with fluorine resin at 18.1soc/50? iron powder was used. Toner 4 was prepared using a toner consisting of 100 parts of styrene acrylic resin, 10 parts of azo pigment, and 5 parts of amino acrylic resin, to which 0.5% of coroiglu silica was externally added. When the same procedure as in Example 1 was carried out using a configuration of 0 or more using the drum 1 OPC photoreceptor, the circulation of the magnetic particles was appropriate, and a thin layer made only of toner could be formed on the surface of the sleeve 20. Furthermore, when the electrostatic charge image on the photosensitive plate drum 1 was developed using this thin layer of toner, an extremely good red developed image was obtained. The above-mentioned developing function remained stable until almost all of the toner 4 was consumed, and there was no leakage to the lower part of the sleeve 2, and the performance was good.

[Example 3] The distance between the blade 6 and the sleeve 2 is 250μ, and the magnetic particles 5 are fluidized dust 28,2(8)150? Example 2 was carried out in the same manner as in Example 2 except that ferrite particles were used, and good results were obtained.

[Example 4] Fluid dust as magnetic particles 5: 38.6 sec/50? Example 2 was carried out in substantially the same manner as in Example 2, except that slightly flat iron powder was used, and good results were obtained.

[Comparative Example 1] The same procedure as in Example 4 was carried out except that flat iron powder of 52.1 sQc 750 t of fluidized dust was used as the magnetic particles 5. As a result, the uniformity of the coating layer on the surface of the sleeve 20 was poor and the concentration was partial. The leakage of magnetic particles was observed at the lower part of the sleeve 2.

Although a non-magnetic developer was used as the toner in this practical experiment, a magnetic developer can also be used as long as it has significantly weaker magnetism than magnetic particles and can be tribocharged.

[Brief explanation of the drawing]

FIG. 1 is a side view of a developing device used to explain the principles of the present invention, and FIG. 2 is a sectional view of the developing device used in an embodiment of the present invention. In the figure, 1 is a photosensitive drum which is a latent image holding member, 2 is a sleeve which is a toner carrier, 3 is a container, 4 is a toner, and 5
are magnetic particles, 6 is a magnetic blade which is a regulating member, and 7 is a magnet.

Claims (2)

[Claims] (1) A developer container that stores toner and magnetic particles for toner application, a toner carrier that conveys the toner to the latent image carrier, and a contact with the toner carrier on the upstream side of the toner outlet of the developer container. A toner application method in which a thin layer of toner is formed on the toner carrier by arranging a magnet forming a magnetic brush made of magnetic particles for toner application, wherein the flow rate of the magnetic particles is 10 to 50 sec/ ' A toner application method characterized by being 50 f. (2) A developer container that stores toner and magnetic particles for applying toner, a toner carrier that conveys the toner to the latent image carrier, and a contact with the toner carrier on the upstream side of the toner outlet of the developer container. Magnetic particles for toner application used in a toner application method in which a thin layer of toner is formed on the toner carrier by arranging a magnet forming a magnetic brush of magnetic particles for toner application, comprising: 50 Takes 150? sensitive particles.