JPH0136103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developer carrying member for imparting a triboelectric charge to an insulating toner used in electrophotography, electrostatic recording, etc., and a method for manufacturing the same.

Conventionally, as an electrophotographic method, U.S. Patent No. 2297691
Specification of No. 42-23910 and Special Publication No. 1973
Many methods are known, as described in Japanese Patent No. 24748, etc., but in general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the A latent image is developed using toner, and after the toner image is transferred to a transfer material such as paper as necessary, it is fixed by heat, pressure, solvent vapor, etc. to obtain a copy.

Various methods are also known for visualizing electrical latent images using toner.

For example, the magnetic brush method described in U.S. Pat. No. 2,874,063, the cascade development method described in U.S. Pat. Many developing methods are known, such as the developing method.

Among these developing methods, in particular, a magnetic brush method using a developer mainly consisting of toner and carrier,
Cascade method, liquid development method, etc. are 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 have been proposed that use a one-component developer consisting only of toner. For example, US Pat. No. 3,909,258 proposes a developing method using an electrically conductive magnetic toner. In this system, a conductive magnetic developer is supported on a cylindrical conductive sleeve having a magnet inside, and is brought into contact with an electrostatic image to develop it. At this time, in the developing section, a conductive path is formed by the toner particles between the recording medium surface and the sleeve surface, and through this conductive path, the sleeve conducts charges to the toner particles, causing a Coulomb force between the electrostatic image and the image area. The toner particles adhere to the image area 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, because the toner is conductive, the developed image can be transferred from the recording medium to the final product such as plain paper. It has the disadvantage that it is difficult to electrostatically transfer it to a permanent support member.

As a developing method using a high-resistance magnetic toner that can be electrostatically transferred, JP-A-52-94140 discloses a developing method that utilizes dielectric polarization of toner particles. However, such a method has drawbacks such as an inherently slow development speed and an inability to obtain a developed image with sufficient density, making it 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 small number of times the toner particles come into contact with the friction member, which tends to result in insufficient triboelectric charging, and the Coulomb force between the charged toner particles and the sleeve increases, making them apt to aggregate on the sleeve. It has many practical difficulties.

The present applicant previously proposed a new developing method that eliminates the above-mentioned drawbacks in JP-A-54-43036.

This involves applying a very thin layer of magnetic toner onto the sleeve, triboelectrically charging it, and then developing it by facing the electrostatic image very close to, but not in contact with, the electrostatic image under the action of a magnetic field.

According to this method, by applying an extremely thin layer of magnetic toner onto the sleeve, the chances of contact between the sleeve and the toner are increased, and sufficient frictional electrification is possible. By moving the toner relatively, the toner particles are disaggregated and are sufficiently rubbed against the sleeve, and the toner is supported by magnetic force and developed by facing the electrostatic image without coming into contact with it. By preventing background fog, etc., excellent images can be obtained. However, this method also has the drawback that image density tends to decrease at high humidity.

Furthermore, since the one-component developing method does not use carrier particles, there is no need to adjust the mixing ratio of carrier particles and toner, and no special stirring operation is required to mix the carrier particles and toner sufficiently and uniformly. This has the advantage that the entire developing device can be configured simply and compactly.

However, in developing methods that use one-component toner, since there are few stirring operations, the extent to which the toner moves from side to side on the toner holding member is extremely small. In parts that are not used at all, the toner retaining member simply rotates with the same toner attached to it, and new toner is hardly supplied. For example, if you copy a large number of A-4 size originals and then copy a wider B-4 size original, the widened part, that is, the A-4 size original on the toner holding member, will completely disappear. A phenomenon is observed in which an image developed by an unused portion has a lower image density than an image developed by a used portion. The reason for this is not clear, but as mentioned above, the one-component toner hardly moves from side to side, and the parts not used for development are constantly rotated repeatedly with almost the same toner attached to the toner holding member. This is thought to be caused by not being supplied with new toner. Furthermore, when a large number of copies are made, there is a problem in that toner particles, especially particles with small particle diameters, tend to stick to a triboelectric charging member such as a developer carrying member, which tends to cause development that reduces the developing ability of the toner.

Therefore, an object of the present invention is (1) to provide a developer carrying member for imparting a triboelectric charge to an insulating toner, which overcomes the above-mentioned drawbacks, and a method for manufacturing the same.

(2) To provide a developer carrying member that has good toner charging properties and provides clear images even under high humidity conditions, and a method for manufacturing the same.

(3) To provide a developer carrying member that does not cause a decrease in image density even when a large number of copies are made, and a method for manufacturing the same.

(4) To provide a developer carrying member in which toner does not stick even when a large number of copies are made, and a method for manufacturing the same.

Specifically, the present invention provides a developer carrying member which is a member for imparting a triboelectric charge to insulating toner and a member for transporting the toner to a developing section, at least a portion that comes into contact with the toner. A developer characterized by having a resin layer on the surface treated with a solution of a thermoplastic resin and a solvent, and further having a resin coating layer on the surface that is heat-treated at a temperature higher than the glass transition temperature of the thermoplastic resin. Relating to a carrier member.

Furthermore, the present invention provides at least a portion of the developer carrying member that contacts the toner, which is a member for imparting a triboelectric charge to the insulating toner and a member for conveying the toner to the developing section, made of thermoplastic resin. The present invention relates to a method for manufacturing a developer carrying member, which comprises treating with a solvent solution to form a resin layer on the surface, and further heat treating at a temperature equal to or higher than the glass transition temperature of a thermoplastic resin.

The developer carrying member used in the present invention has a shape such as a cylinder, an endless belt, or a cylindrical screen.

The substrate is preferably made of metal such as stainless steel, aluminum, or copper.

The thermoplastic resin to be coated on the substrate includes styrenic polymers such as polystyrene, monopolymers of styrene and its substituted products such as polyP-chlorostyrene and polyvinyltoluene, styrene-P-chlorostyrene copolymers, and styrene-P-chlorostyrene copolymers. 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-ptadiene copolymer, styrene-isoprene copolymer, styrene-
Acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, etc.

Acrylic polymer, polyphenylene oxide,
porsulfone, polycarbonate, polyamide,
Polyvinyl chloride, polyvinyl acetate, vinyl chloride
Examples include vinyl acetate copolymers, epoxy resins, polyesters, polyurethanes, phenolic resins, and cellulose resins.

The thermoplastic resin referred to in the present invention is, in a broad sense, a resin that becomes plasticized by the application of heat, and refers to a resin that has this property after heat treatment in the present invention.

For example, epoxy resins are usually classified as thermosetting resins, but if epoxy resins are simply heat-treated as in the present invention, they hardly harden, and even after heat treatment they usually behave as thermoplastic resins. In the present invention, such resins are also referred to as thermoplastic resins.

Further, thermoplastic resins having a glass transition temperature of 40° C. or higher are generally preferred. In addition, well-known substances can be used as the solvent used to apply these resins, such as ketones such as methyl ethyl ketone and acetone, ethers such as methyl ethyl ether and diethyl ether, and aromatic substances such as benzene, toluene, and xylene. family solvents, aliphatic solvents such as n-hexane and heptane, esters such as ethyl acetate, alcohols such as methanol and ethanol propanol, solvents containing halogens such as carbon tetrachloride and trichloroethylene dichloroethane, water, etc. can be used alone or in combination. Methods for coating the substrate include well-known methods such as dipping, brush coating, and spraying, but dipping is preferred in terms of obtaining a uniform coating.

As in the examples described later, in the present invention, a solution layer is formed on the surface by treatment with a solution of a thermoplastic resin, and dried at a temperature below the boiling point of the solvent of the solution,
Next, heat treatment at a temperature equal to or higher than the glass transition temperature of the thermoplastic resin is preferred in order to obtain a uniform coating.

Furthermore, in order to improve the adhesion between the substrate and the thermoplastic resin layer, the substrate may be treated before coating, or an intermediate layer may be provided between the substrate and the thermoplastic resin layer.

In the thermoplastic resin layer, other suitable polymers and conductive aids such as carbon black and fine metal powder may be added for the purpose of improving various properties such as coating properties and durability, and for other purposes. Reinforcing members such as glass fiber and stainless steel filament, coroital silica, etc. can be added.

The developer carrying member of the present invention is further subjected to heat treatment at a temperature higher than the glass transition temperature of the thermoplastic resin used in the present invention, but the temperature does not decompose the thermoplastic resin or reduce the strength of the coating. It is necessary to have a temperature lower than the glass transition temperature by 5 to
It is preferably 400°C, particularly 10 to 250°C higher. However, the heat treatment temperature in the present invention is the temperature of the substrate surface.

The treatment time is about 1 minute to 5 hours, preferably about 5 to 60 minutes.

The glass transition temperature of thermoplastic resins can be measured using a differential scanning calorimeter.

An apparatus method to which the developer carrying member of the present invention can be applied will be described 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 developer carrying member according to the present invention can be applied, but of course 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. A belt-shaped one is also possible. Reference numeral 2 represents a known photosensitive charging device, and 3 represents a light image irradiation device that projects an original image, a light image, or a light beam modulated by an image signal. 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. Furthermore, it is also possible to adopt a so-called electrostatic image transfer method in which the electrostatic image on the photoreceptor 1 is temporarily transferred to another image carrier, and then converted 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, a developing process to which the developer carrying member of the present invention is applied will be explained. FIG. 2 shows a cross-sectional view of an embodiment of a developing process to which the developer carrying member of the present invention is applied. 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 as not to rotate, so the surface, which is the developer carrier, is coated with a thermoplastic resin coating approximately 10μ thick. By rotating the non-magnetic cylinder 4b, which is the triboelectric charging member of the present invention, in the same direction as the electrostatic image holding surface 1,
A one-component insulating magnetic developer 11 containing no carrier particles sent from a developer container 12 is applied onto a non-magnetic cylindrical surface, and the friction between the cylindrical surface and the toner particles imparts an electrostatic image charge to the toner particles. gives a charge of opposite polarity. In addition, iron doctor blade 10
By arranging the toner layer close to the cylindrical surface (with a spacing of 50μ to 500μ) 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 (30μ to 300μ). ) and uniformly regulated. By adjusting the rotational speed of the cylinder 4b, 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, a bias may be applied between the developer carrier and the electrostatic image holding surface.

The insulating developing powder used in the present invention includes a binder resin,
It consists of additives such as a coloring agent, a charge control agent, a fixing aid, and an anti-caking agent, and any known materials can be used. For example, examples of the binder resin include monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene, styrene-P-chlorostyrene copolymers, styrene-propylene copolymers, and styrene-propylene copolymers.
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- α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, Styrenic copolymers such as styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, polymethyl methacrylate, polybutyl methacrylate, polychloride Vinyl, 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,
Parafine wax and the like can be used alone or in combination. Additives such as colorants, charge control agents, fixing aids, and anti-caking agents include carbon black, various dyes and pigments, plasticizers, colloidal silica, and talc.

Furthermore, when used as magnetic developer powder, ferromagnetic elements and alloys and compounds containing these, such as iron such as magnetite, hematite, and phaate, cobalt, nickel, manganese, and other alloys and compounds, etc. of materials traditionally known as magnetic materials, such as ferromagnetic alloys.
Fine particles of about 0.1 to 5 microns can be contained.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 100 parts by weight of zinc oxide, 20 parts by weight of styrene-butadiene copolymer, 40 parts by weight of n-butyl methacrylate, 120 parts by weight of toluene, 1% rose bengal.
A mixture consisting of 4 parts by weight of methanol solution was dispersed and mixed in a ball mill for 6 hours. This was applied to a 0.05 mm thick aluminum plate using a wire bar so that the dry coating thickness was 40 μm, and the solvent was evaporated with warm air to produce a zinc oxide-binder photoreceptor. This photoreceptor was subjected to -6 KV corona discharge to uniformly charge the entire surface, and then an original image was irradiated to form an electrostatic latent image.

On the other hand, a solution consisting of 5 parts by weight of styrene-methyl methacrylate copolymer (monomer ratio 8:2 Tg: 82°C) and 100 parts by weight of toluene (boiling point about 110°C) was applied to the surface of a stainless steel cylinder with an outer diameter of 50 mm. 70℃
The mixture was dried in an atmosphere of 1 hour for 1 hour, and further treated at 110°C for 30 minutes to form a styrene-methyl methacrylate copolymer layer of about 10μ.

The latent image was developed using this cylinder as a sleeve, fixed with a rotating sleeve magnet (sleeve circumferential speed was the same as that of the drum, but the direction of rotation was opposite), 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. Set the distance between the photosensitive drum surface and the sleeve surface to 0.25 mm, and
Styrene-butyl acrylate copolymer was tested by applying 200Hz, 600V AC and -150V DC bias.
90 parts by weight, 10 parts by weight of styrene-butyl acrylate-diethylaminoethyl methacrylate copolymer,
It was developed using a developer consisting of 60 parts by weight of magnetic powder and 1 part by weight of colloidal silica, and then the powder image was transferred while irradiating -7 KV DC corona from the back side of the transfer paper to obtain a copied image. The remaining developer on the photosensitive drum was removed using a magnetic brush cleaner, and the fixing was carried out 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 potential of the toner layer on the sleeve was measured with a surface electrometer and was +35V. High temperature and high humidity (35℃
85% RH), and a clear image was obtained.

Furthermore, after copying 1000 sheets of A4 size paper, I made a B4 size copy, but there was almost no observed phenomenon in which the image density (Dmax) became thinner in the area where the width increased. Further, a running test was conducted up to 10,000 sheets, but no toner was observed to adhere to the sleeve surface, and good images were obtained.

Example 2 A solution consisting of 7 parts by weight of polyether sulfon (trade name, Victrex 200P Tg: 225°C, manufactured by ICI) and 100 parts by weight of toluene was applied to the surface of an aluminum cylinder with an outer diameter of 50 mm, and heated at 70°C. in the atmosphere
Dry for 1hr, then treat at 300℃ for 50min, about 15μ
A thick polyether sulfone layer was formed. The same procedure as in Example 1 was carried out except that this cylinder was used as a sleeve. Clear, high-resolution images were obtained. Even after a durability test of 20,000 sheets, no toner adhesion was observed on the sleeve surface.

Example 3 A solution consisting of 6 parts by weight of polycarbonate (Tg: 180°C) synthesized from bisphenol A and phosgene and 100 parts by weight of toluene was applied to the surface of a stainless steel cylinder with an outer diameter of 50 mm and heated in an atmosphere of 70°C. in
Dry for 1hr, then treat at 250℃ for 30min, about 10μ
A thick coating layer was obtained. The same procedure as in Example 1 was carried out except that this cylinder was used as a sleeve. Good results were obtained.

Example 4 A solution consisting of 4 parts by weight of polyphenylene oxide (Tg: 210°C) and 100 parts by weight of toluene was applied to the surface of a stainless steel cylinder with an outer diameter of 50 mm, dried in an atmosphere of 70°C for 1 hour, and then dried for 350°C. C. for 20 minutes to obtain a coating layer with a thickness of approximately 10 μm. The same procedure as in Example 1 was carried out except that this cylinder was used as a sleeve. A clear image was obtained. Furthermore, images were produced at high temperature and high humidity (35°C, 85% RH), and clear images with high density were obtained.

Even after a durability test of 20,000 sheets, no toner adhesion was observed on the sleeve surface.

Example 5 7 parts by weight of an epoxy resin (Tg: 60°C) synthesized from bisphenol A and epichlorohydrin,
Polytetrafluoroethylene powder (average particle size 0.3μ)
A solution consisting of 3 parts by weight and 100 parts by weight of benzene (boiling point approximately 80°C) was applied to the surface of an aluminum cylinder with an outer diameter of 50 mm, dried in an atmosphere of 60°C for 1 hour, and then
It was treated at 100°C for 60 minutes to obtain a coating layer with a thickness of about 15μ. The same procedure as in Example 1 was carried out except that this cylinder was used as a sleeve. A clear image was obtained. Even after a durability test of 10,000 sheets, no toner adhesion was observed on the sleeve surface.

Comparative Examples 1 to 5 Examples 1 to 5 were carried out in the same manner as in each Example except that no heat treatment was performed. After conducting a durability test of 10,000 sheets, it was found that toner did not stick to the sleeve surface. Admitted.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an example of a copying device or a recording device to which a developing method according to the present invention can be applied. FIG. 2 is a sectional view of one embodiment of the developing process used in the present invention. 1...Photosensitive drum. 4...Developing device. 4a...
Toner carrier. 4b...Nonmagnetic cylinder. 9... Magnet Troll. 10...Doctor Blade. 11
...Insulating magnetic toner.

Claims (1)

[Scope of Claims] 1. A developer carrying member, which is a member for imparting a frictional charge to the insulating toner and a member for transporting the toner to the developing section, is made of thermoplastic resin at least in the portion that comes into contact with the toner. and a solvent solution to form a resin layer on the surface, and further heat treatment at a temperature equal to or higher than the glass transition temperature of the thermoplastic resin. 2 The surface of the developer carrier is treated with a solution of a thermoplastic resin to form a solution layer on the surface, dried at a temperature below the boiling point of the solvent of the solution, and then heated at a temperature above the glass transition temperature of the thermoplastic resin. 2. The method for manufacturing a developer carrying member according to claim 1, wherein the heat treatment is carried out at a high temperature. 3. In the developer carrying member, which is a member for imparting a triboelectric charge to the insulating toner and a member for transporting the toner to the developing section, at least the portion that comes into contact with the toner is coated with a solution of thermoplastic resin and a solvent. 1. A developer-carrying member characterized in that the developer-carrying member has a resin layer on the surface thereof which has been treated, and further has a resin coating layer on the surface which has been heat-treated at a temperature equal to or higher than the glass transition temperature of a thermoplastic resin. 4. The resin coating layer is formed by treating the surface of the developer carrier with a solution of a thermoplastic resin to form a solution layer on the surface, drying at a temperature below the boiling point of the solvent of the solution, and then treating the surface of the developer carrier with a solution of the thermoplastic resin. 4. The developer carrying member according to claim 3, wherein the developer carrying member is heat-treated at a temperature equal to or higher than the glass transition temperature of the developer.