JPH0473787B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of developing electrical latent images with a one-component insulating toner.

The conventional electrophotographic method is US Patent No. 2297691.
specification, Japanese Patent Publication No. 42-23910 (U.S. Patent No.
3666363) and Japanese Patent Publication No. 43-24748 (U.S. Pat. No. 4,071,361), a number of methods are known. Form an electrical latent image on the photoreceptor by the means described above, then develop the latent image with toner to make a visible image, and if necessary, transfer the toner image to a transfer material such as paper, and then Copies are obtained by fixing by heating, pressure, etc.

Various developing methods are also known in which an electrostatic latent image is visualized using toner. For example, US Patent No.
The magnetic brush method described in specification No. 2874063,
The cascade development method described in Specification No. 2618552, the powder cloud method and fur brush development method described in Specification No. 2221776,
A number of development methods are known, such as liquid development. Among these developing methods, the magnetic brush method, cascade method, liquid developing method, etc., which use a developer mainly consisting of toner and carrier, are in particular widely put into practical use. All of these methods are excellent methods in which good images can be obtained relatively stably, but on the other hand, they have common drawbacks associated with two-component developers, such as deterioration of the carrier and fluctuations in the mixing ratio of toner and carrier.

In order to avoid such drawbacks, various development methods using a one-component developer made only of toner have been proposed, but among them, many methods using a developer made of magnetic toner particles are superior. .

US Pat. No. 3,909,258 proposes a developing method using an electrically conductive magnetic toner. In this method, conductive magnetic toner is supported on a cylindrical conductive sleeve having magnetism inside, and is brought into contact with an electrostatic image to be developed. At this time, in the developing section, a conductive path is formed by the toner particles between the surface of the recording medium and the surface of the sleeve, and charges are guided from the sleeve to the toner particles through this conductive path, thereby creating a connection between the image area of the electrostatic image and the image area of the electrostatic image. The toner particles adhere to the image area due to the Turron force and are developed. This developing method using conductive magnetic toner is an excellent method that avoids the problems associated with conventional two-component developing methods, but on the other hand, since the toner is conductive, the developed image can be transferred from the recording medium to plain paper, etc. It has the disadvantage that it is difficult to transfer electrostatically to the final support member.

As a developing method using a high-resistance magnetic toner that can be electrostatically transferred, there is a developing method that utilizes dielectric polarization of toner particles. However, such a method inherently has drawbacks such as slow development speed and insufficient density of the developed image, and is difficult in practice.

Another developing method using high-resistance magnetic toner is a method in which the toner particles are triboelectrified by friction between the toner particles or friction between the toner particles and a sleeve, etc., and the toner particles are brought into contact with an electrostatic image holding member for development. It has been known. However, these methods have drawbacks such as the number of times the toner particles come into contact with the friction member is small and frictional charging tends to be insufficient, and the Coulomb force between the charged toner particles and the sleeve increases and they tend to aggregate on the sleeve. However, it was difficult to implement in practice.

However, in JP-A-55-18656, etc.
A new development method has been proposed which eliminates the above-mentioned drawbacks. This involves applying a very thin layer of magnetic toner onto the sleeve, triboelectrically charging it, and then developing it in close proximity to the electrostatic image. This method increases the mechanical contact between the sleeve and toner by applying an extremely thin layer of magnetic toner onto the sleeve, which enables sufficient frictional electrification, supports the toner by magnetic force, and connects the magnet and toner. By moving the toner particles relative to each other, mutual agglomeration is eliminated and sufficient friction with the sleeve is achieved, and the toner is supported by magnetic force and developed by facing the electrostatic image without coming into contact with it. Excellent images can be obtained by preventing background fog.

Since these one-component developing methods using magnetic toner do not use a carrier, there is no need to adjust the mixing ratio of the carrier and toner, and there is no need for stirring operations to mix the carrier and toner sufficiently uniformly. Since this is not necessary, there is an advantage that the entire developing device can be constructed simply and compactly.

However, in all developing methods using a one-component developer, a relatively thin and uniform toner layer must be formed on the developer-carrying member, but environmental conditions, toner physical properties, physical properties of the developer-carrying member surface, etc. , it is not possible to obtain a uniform toner layer,
Particularly in low humidity environments, unevenness often occurs.

In terms of imparting a triboelectric charge to the toner, development is basically the same as development using a two-component developer, but when developing using a one-component insulating toner, it is difficult to distribute the toner uniformly on the toner carrier. It is important to apply the developer to the surface of the developer and maintain the state stably, which is significantly different from development using a two-component developer, including the above-mentioned problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing method using a one-component insulating toner that does not suffer from the above-mentioned drawbacks.

Another object of the present invention is to provide a developing method in which toner has extremely good chargeability and clear images can be obtained.

Another object of the present invention is to provide a developing method that does not reduce image density during repeated copying.

Another object of the present invention is to provide a developing method that does not cause coating unevenness or image density unevenness under low humidity conditions. In a method of developing an electrical latent image using toner, the surface of the member that imparts a triboelectric charge to the insulating toner is subjected to blasting treatment with an abrasive and blasting treatment with an organic compound charged to the same polarity as the insulating toner. The present invention relates to a developing method characterized in that a frictional charge is applied to an insulating toner using the blast-treated member.

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

FIG. 1 shows a schematic configuration of an example of a copying device or a recording device to which the developing method according to the present invention can be applied, but the present invention is not limited thereto.

Reference numeral 1 corresponds to an electrostatic image carrier, and is a photosensitive drum containing a photoelectrostatic layer, and any type with or without an insulating layer on the surface can be used. It is also possible to make it into a belt shape. Reference numeral 2 designates a well-known photosensitizing charging device, and 3 designates a light image irradiation device that projects a light beam modulated by an optical image or an image signal on the back of the document. As a result, an electrostatic image is formed on the photoreceptor 1. A developing device 4 has a developer carrier 4a, and forms a toner particle visual image in accordance with the electrostatic image on the photoreceptor 1. 5 is a device for transferring the toner image onto a transfer material 6. Incidentally, in order to improve the transferability, the visible image may be charged in advance by corona discharge or the like before transfer. Further, the electrostatic image on the photoreceptor 1 is temporarily transferred to another image carrier, and the developing device 4 converts the electrostatic image into a visible image. It is also possible to employ a so-called electrostatic image transfer method. Reference numeral 7 denotes a fixing device for fixing the toner image on the transfer target member 6, which is composed of at least two rollers having pressure or heating pressure means. Reference numeral 8 denotes a cleaning device for cleaning and removing residual toner on the photoreceptor 1 after transfer, so that the photoreceptor 1 can be reused.

Next, the developing process used in the present invention will be explained. FIG. 2 shows a cross-sectional view of one embodiment of the developing process used in the present invention. In the same figure, when the electrostatic image holding surface 1 moves in the direction of the arrow, the multipolar permanent magnet 9 is fixed so that it does not rotate, so the surface that is the developer material carrier is blasted with an abrasive and the same as the toner. By rotating the non-magnetic cylinder 4b blasted with a polarized organic compound in the same direction as the electrostatic image holding surface 1, the one-component insulating magnetic developer 11 sent from the developer container 12 is transferred to the non-magnetic cylindrical surface. The toner particles are applied with a charge having a polarity opposite to that of the electrostatic image charge due to friction between the cylindrical surface and the toner particles. Furthermore, by arranging the iron doctor blade 10 close to the cylindrical surface (with an interval of 50 μm to 500 μm) and facing one magnetic pole (S pole in the figure) of the multipolar permanent magnet 9, the thickness of the toner layer can be reduced. Regulate thinly (30μ to 300μ) and uniformly. This cylinder 4
By adjusting the rotational speed of b, the surface speed and preferably the internal speed of the developer layer are made to be substantially equal to or close to the speed of the electrostatic image holding surface. As the doctor blade 10, a permanent magnet may be used instead of iron to form opposing magnetic poles. Further, in the developing section, an alternating current bias may be applied between the developer carrier and the electrostatic image holding surface.

In the present invention, the member that applies a triboelectric charge to the one-component insulating developer powder is a member that can come into contact with the developer powder and provide or supplementally provide the charge necessary for development, such as a sleeve, These include a doctor blade, a scraper for removing residual developer powder on the sleeve after development, and other flexible members provided to come into contact with the developer powder to impart a triboelectric charge.

When a tribo-charging member, especially a tribo-charging member that also serves as a developer support member, is processed according to the present invention, the surface of the tribo-charging member becomes rough with unevenness, and a part of the surface is tribo-electrified to the same polarity as the toner. The organic compounds attached firmly adhere to the surface. When the surface of the triboelectric charging member, especially the triboelectric charging member that also serves as a developer support member, is treated to obtain the above-mentioned state, the charging property of the toner becomes extremely stable even under low humidity compared to an untreated state. That is, by treating the surface of the triboelectric charging member,
Since an organic compound that is charged to the same polarity as the toner is present on a part of the surface of the triboelectric charging member, excessive charging of the toner under low humidity is suppressed, and the amount of charge of the toner is stabilized. Therefore, even under low humidity, the amount of thin layer of toner applied to the developer supporting member is made uniform, and uneven coating and uneven image density do not occur. Furthermore, when a triboelectric charging member that also serves as a developer support member is blasted with a mixture of an abrasive and an organic compound that charges to the same polarity as the toner, the surface of the developer support member becomes rough with unevenness, making it more uniform. A thin layer of toner can be applied, and the thickness of the toner layer will not be uneven, and an image with stable image density can be obtained.

As the blasting method used in the present invention, techniques such as known sandblasting methods can be used.
Furthermore, the organic compound charged to the same polarity as the toner used in the present invention may be used in combination with an abrasive such as abrasive particles.

Examples of organic compounds that are charged to the same polarity as the toner used in the present invention include substances that have conventionally been used as charge control agents.For example, negatively charged substances include metal complex dyes and metal complex salts, and positively charged substances include nigrosine. and quaternized alkylammonium salts.

In addition, resins can also be used as organic compounds that are charged to the same polarity as the toner, such as monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene; styrene-P-chlorostyrene copolymers. , styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene 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-alpha chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isobrene copolymer, styrene-
Styrenic copolymers such as acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene , polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin Wax etc. can be used alone or in combination.

Further, a charge control agent may be added to the above resin.

The one-component insulating toner of the present invention is composed of a binder resin, a colorant, and optionally additives such as a charge control agent and an anti-caking agent, and known materials can be used for each of them.

As the binder resin for the toner, monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene; styrene-P-chlorostyrene copolymers, styrene-propylene copolymers, and styrene-vinyl Toluene copolymer, styrene-vinylnaphthalene 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-alpha chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isobrene copolymer, styrene-
Styrenic copolymers such as acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene , polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin Wax etc. 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,
There are known dyes and pigments such as iron black, phthalocyanine blue, ultramarine blue, quinacridone, and benzidine yellow.

When the toner is a magnetic toner, ferromagnetic elements such as iron, cobalt, and nickel, or iron such as magnetite, hematite, and ferrite,
It is sufficient to contain a magnetic material such as an alloy or compound of cobalt, nickel, or manganese, or other ferromagnetic alloy.

Additives may be mixed with the toner as necessary. Examples of such additives include Teflon,
A lubricant such as zinc stearate, a fixing aid (for example, low molecular weight polyethylene, etc.), a fluidity imparting agent, an anti-caking agent (for example, colloidal silica, etc.), or a metal oxide such as tin oxide as a conductivity imparting agent. be.

It is also possible to have the above toner structure supported on the wall material, the core material, or both of them in the microcapsule toner.

[Example 1] In Fig. 2, an aluminum sleeve with a diameter of 20 mm was first used as a non-magnetic sleeve as a developer supporting member, using only #400 carbon random, the spray nozzle diameter was 7φ, the distance was 100 mm, and the air pressure was 4 Kg/cm ² ,2
Fine powder of polymethyl methacrylate (average particle size
7μ), and blasting was performed again.

Insert this sleeve into a commercially available plain paper copier (product name).
PC-20, manufactured by Canon), 80 parts by weight of styrene-butyl methacrylate copolymer, styrene-butyl methacrylate copolymer,
20 parts by weight of butadiene copolymer, 60 parts by weight of magnetic powder,
A positively charged toner consisting of 2 parts by weight of nigrosine, and 0.5 wt% of silica, which is obtained by hydrophobicizing colloidal silica produced by a wet method, based on the toner.
The image density was 1.2 and the image density was 4000 while replenishing toner.
Although copying was repeated, the image density and quality were almost the same as before the durability test.

Furthermore, even under low temperature and low humidity conditions (10° C., 10%), the image density remained around 1.0 with no decrease in density, the coating layer was uniform, there was no coating unevenness, and no density unevenness occurred in the image.

[Example 2] A styrene sleeve with a diameter of 30φ was used as a non-magnetic sleeve as a developer support member, and 2wt% of a negatively charged metal complex dye (trade name: Zabon First Black BCIAcid) was used as a blasting abrasive grain.
The same sandblasting treatment as in Example 1 was performed using #600 carbon random containing Black 63 (manufactured by BASF).

The surface of the insulating layer of the photosensitive drum, which consists of three layers: an insulating layer made of polyester resin, a photosensitive layer made of CDS and acrylic resin, and a conductive substrate, is uniformly charged by +6KV corona discharge, and then the original image is irradiated simultaneously. After 7 KV alternating current corona discharge, the entire surface was uniformly exposed to form an electrical latent image on the surface of the photoreceptor.

The latent image was fixed using a sleeve rotating magnet with a magnetic flux density on the sleeve surface of 700 Gauss and a distance between the ear cutting blade and the sleeve surface of 0.2 mm (the peripheral speed of the sleeve was the same as that of the drum, but the direction of rotation was opposite). Set the developing device at a distance of 0.25 mm between the photosensitive drum surface and the sleeve surface, and
By applying 800Hz 1KV AC and 150V DC bias, styrene-butyl methacrylate copolymer
100 parts by weight of magnetic powder, 2 parts by weight of chromium complex salt of ditertiary butylsalicylic acid as a negative charge control agent, and hydrophobic colloidal silica as an external additive to the toner. 0.3wt% of the powder is used as a developer to develop the powder image, and then the powder image is transferred while irradiating +7KV DC corona from the back side of the transfer paper.
A duplicate image was obtained. The remaining developer on the photosensitive drum was removed using a magnetic brush cleaner, and fixing was carried out using a commercially available plain paper copying machine (trade name: NP-5000, manufactured by Canon). The images obtained were clear, had high resolution, and were free from fog. The image density was 1.3, and even after 10,000 copies were made, the image density and image quality were almost the same as before durability.

Furthermore, even under low temperature and low humidity (10°C, 10%), the image density was 1.0 or more before and after the durability test, and good images were obtained, and even after the durability test, problems such as uneven coating and uneven density did not occur. Ta.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing an example of a copying device or a recording device to which the developing method according to the present invention can be applied, and FIG. 2 is a sectional view showing an embodiment of the developing process. 1... Electrostatic image holder, 4... Developing device, 4a...
...Developer carrier, 9...Magnet, 11...Developer.

Claims (1)

[Scope of Claims] 1. A method for developing an electrical latent image using triboelectrically charged insulating toner without using carrier particles, wherein the surface of the member imparting triboelectric charge to the insulating toner is polished. A developing method characterized in that the insulating toner is subjected to a blasting treatment with an agent and a blasting treatment with an organic compound charged to the same polarity as the insulating toner, and the blasted member imparts a triboelectric charge to the insulating toner. 2. The development according to claim 1, wherein the surface of the member is blasted with an abrasive to form irregularities, and then subjected to blasting with an organic compound charged to the same polarity as the insulating toner. Method. 3 The member that applies a frictional charge to the insulating toner is
The developing method according to claim 1, which is a developing sleeve.