JPH0473786B2 - - 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.

Conventional electrophotographic methods include US Pat.
A number of methods are known, as described in Japanese Patent Publication No. 3666366) and Japanese Patent Publication No. 43-24748 (U.S. Patent No. 4071361), but generally, they utilize a photoconductive substance, An electrical latent image was formed on a photoreceptor by various means, and then the latent image was developed with toner to become a visible image, and if necessary, the toner image was transferred to a transfer material such as paper. After that, it is fixed by heating, pressure, etc. to obtain the object.

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 the specification No. 2618552, the Bauder Klund method and the fur brush development method described in the specification No. 2221776,
A number of development methods are known, such as liquid development. Among these developing methods, a magnetic brush method, a cascade method, a 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 inductive magnetic toner. In this method, conductive magnetic toner is supported on a cylindrical inductive 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 part is formed by the toner particles between the recording medium surface and the sleeve surface, and charges are guided from the sleeve to the toner particles through this conductive path, and due to the Coulomb force with the image part of the electrostatic image. Toner particles adhere to the image area and are developed. The developing method using this conductive magnetic toner is the conventional 2
This is an excellent method that avoids the problems associated with component development methods, but on the other hand, since the toner is conductive,
A drawback is that it is difficult to electrostatically transfer the developed image from the recording medium to the final support member such as plain paper.

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

Another developing method using high-resistance magnetic toner is a method in which toner particles are triboelectrically charged due to friction between toner particles or friction between toner particles and a sleeve, etc., and are brought into contact with an electrostatic image holding member for development. It has been known. However, these methods have disadvantages 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 charged toner particles tend to aggregate on the sleeve due to the strong Coulomb force between them and the sleeve. However, it was difficult to implement in practice.

However, in JP-A-55-18656,
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 chances of 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.

These one-component developing methods using magnetic toner do not use a carrier, so there is no need to adjust the mixing ratio of carrier and toner, and a stirring operation is especially required to mix the carrier and toner sufficiently and uniformly. Since the developing device does not require a large amount of space, it has the advantage that the entire developing device can be constructed simply and compactly.

However, these methods are greatly affected by humidity conditions or the surface properties of the triboelectric charging member. For example, in a high-humidity environment, the amount of triboelectric charge between the toner and the triboelectric charging member decreases, resulting in a decrease in amorphous quality and image density.

In addition, 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, and unevenness often occurs, especially in a low humidity environment.

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, and this is significantly different from development using a two-component developer, including the above-mentioned problems.

The object of the present invention is to avoid the above-mentioned drawbacks.
An object of the present invention is to provide a developing method using a one-component insulating toner.

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

Another object is to provide a developing method in which the density of both images does not decrease with repeated copying.

Another object is to provide a developing method in which image density hardly decreases under high humidity conditions.

Specifically, the present invention provides a method for developing an electrical latent image using an insulating toner triboelectrically charged without using carrier particles, in which the surface of a member imparting a triboelectric charge to the insulating toner is , a development characterized in that the member is subjected to a blasting process using an abrasive and a blasting process using an organic compound that is charged with a polarity opposite to that of the insulating toner, and the blasted member imparts a triboelectric charge to the insulating toner. Regarding the method.

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.

1 corresponds to an electrostatic image holder, and is a photosensitive drum containing a photoelectrostatic layer.It can be used with or without an insulating layer on the surface, and of course is not limited to a drum shape but also a sheet shape. , a belt-like one is also possible. 2 is a well-known photosensitive charging device, 3 is after the original,
Alternatively, it is a light image irradiation device that projects a light image or a light beam modulated by both image signals. 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 visible image according to the electrostatic image on the photoreceptor 1. 5 is a device for transferring the toner image onto a transfer material 6. In order to improve transferability, charges may be applied to the transferred image in advance by corona discharge or the like. It is also possible to adopt a so-called electrostatic image transfer method, in which the electrostatic image on the photoreceptor 1 is once transferred to another image carrier itself, and this is made into a visible image by the developing device 4. 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 figure, when the electrostatic image holding image 1 acts 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 carrier is blasted with an abrasive and the toner is By rotating the non-magnetic cylinder 4b which has been blasted with an organic compound charged with an 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 onto the non-magnetic cylindrical surface. The toner particles are applied with a load having a polarity opposite to 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. Instead of iron as the doctor blade 10, a permanent magnet may be used to form the 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 contact the developer powder and apply or supplementally apply the charge necessary for development, such as a sleeve. , a doctor blade, a scraper for removing developer powder remaining on the sleeve after development, and other flexible members provided so as to come into contact with developer powder to impart a triboelectric charge.

When a triboelectric charging member, particularly a triboelectric charging member that also serves as a developer support member, is processed according to the present invention, the surface of the triboelectric charging member becomes a rough surface with unevenness, and furthermore, a part of the surface is triboelectrically charged opposite to the toner. The organic compound attached firmly adheres or forms a very thin film. When the surface of the triboelectric charging member, especially the triboelectric charging member that also serves as a development support member, is treated to obtain the above-mentioned state, the toner loadability is extremely excellent compared to an untreated state. Furthermore, when a triboelectric charging member is coated with an organic compound that is charged in the opposite direction to that of the toner, together with a polymer, the coating has a considerable thickness, so the electric charge generated on the coating due to friction with the toner is accumulated, and the coulomb When the toner is strongly attracted to the surface by force and a large number of copies are made, the image density gradually decreases. On the other hand, when processed according to the present invention, the organic compound that is charged oppositely to the toner adheres firmly to a part of the surface of the triboelectric charging member or forms a very thin film, so that the friction with the toner is The electric charge generated by the toner leaks through the conductive triboelectric charging member, so there is no accumulation of electric charge, no decrease in image density even when a large number of copies are made, and a stable electric charge can be applied to the toner. .

In addition, since the toner is charged by an organic compound that is charged oppositely to the toner on the triboelectric charging member, even under high humidity conditions, a higher charge is given to the toner compared to untreated toner, resulting in lower image density. The higher the price, the better the image quality.

Furthermore, when a triboelectric charging member that also serves as a developer support member is treated with a mixture of an abrasive and an organic compound that charges oppositely to the toner, the surface of the developer support member becomes uneven and rough, resulting in a uniform thin layer of toner. Therefore, unevenness in the toner layer thickness can be prevented, and an image with uniform 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 that is charged oppositely to 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 metal complex dyes and metal complex salts. Examples include nigrosine and quaternized alkylammonium salts.

Further, as the organic compound charged to the same polarity as the toner, resins can also be used, such as monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene; Polymer, 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,
Styrenic copolymers such as styrene-acrylonitrile-indene copolymer, styrene-maleic 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. are used alone or in combination. can.

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- 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-α chloromethyl methacrylate copolymer,
Styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl 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, and 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, there are known dyes and pigments such as carbon black, iron black, phthalocyanine blue, gun blue, quinacridone, and benzidi yellow.

When the toner is a magnetic toner, magnetic toners such as ferromagnetic elements such as iron, cobalt, and nickel, alloys and compounds of iron, cobalt, nickel, and manganese such as magnetite, hematite, and ferrite, and other ferromagnetic alloys are used. It is sufficient to contain the body.

Additives may be mixed with the toner as necessary. Examples of such additives include Teflon,
A lubricant such as zinc stearate, a fixing aid (such as low molecular weight polyethylene), a fluidity imparting agent, an anti-caking agent (such as colloidal silica), or a metal oxide such as tin oxide as a dielectric property 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, a stainless steel sleeve with a diameter of 50 mm was used as a non-magnetic sleeve as a developer supporting member.
Contains 2wt% nigrosine as blasting abrasive grains〓
Sandblasting was carried out using No. 600 carbon random under the conditions of a spray nozzle diameter of 7φ, a distance of 100 mm, an air pressure of 4 Kg/cm ² , and a duration of 2 minutes.

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 CdB and acrylic resin, and a conductive substrate, is uniformly charged by +6KV corona discharge, and then 7KV is applied at the same time as the original image is irradiated. After performing 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 is fixed to a sleeve rotating magnet (sleeve circumferential speed is the same as that of the drum, but the direction of rotation is opposite) with a sleeve surface magnetic flux density of 700 Gauss and a distance between the ear cutting blade and sleeve surfaces of 0.2 mm using the above sleeve. The distance between the photosensitive drum surface and the sleeve surface is set to 0.25 mm, and the sleeve has a distance of 800 mm.
Styrene-butyl methacrylate copolymer 100% by applying Hz 1KV AC and 150V DC bias
0.3 wt% of hydrophobic colloidal silica is added to the toner as an external additive to a negatively charged toner consisting of 60 parts by weight of magnetic powder and 2 parts by weight of a metal complex dye as a negative charge control agent. The mixed material was used as a developer for development, and then the powder image was transferred while irradiating +7KV direct current corona from the back side of the transfer paper to obtain a duplicate image. The remaining developer on the photosensitive drum is removed using a magnetic brush cleaner, and the fixing is done using a commercially available plain paper copying machine (product 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 high temperature and high humidity conditions (35° C., 85%), a good image was obtained with an image density of 1.2.

[Example 2] As a non-magnetic sleeve as a developer support member, an aluminum sleeve with a diameter of 20 mm was first sandblasted in the same manner as in Example 1 using only carbon random, and then a negatively charged metal complex salt was applied. Blasting was performed once again using fine powder of polymethyl methacrylate (average particle size: 7 μm) containing 10 wt % of dye.

This sleeve is attached to 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 development test was conducted by adding 0.5 wt % of hydrophilic colloidal silica to a positively charged toner containing 2 parts by weight of nigrosine as a developer.

The image density was 1.4, and even under high temperature and high humidity conditions, the image density was 1.0 or higher, and clear images without fog were obtained.

[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. FIG. 2 is a sectional view showing one 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 opposite polarity to that of 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 opposite polarity to 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.