JPS645703B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for developing an electrical latent image using a one-component insulating toner triboelectrically charged by a triboelectric charging member containing an aliphatic fluorine-containing compound at least on its surface. Conventionally, as an electrophotographic method, U.S. Patent No. 2297691
Specification, Special Publication No. 42-23910 and Special Publication No. 43
A number of methods are known, as described in Japanese Patent Application 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 photoreceptor is 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, 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, among which many methods are superior to methods using a developer made of magnetic toner particles.
US Pat. No. 3,909,258 proposes a developing method using an electrically conductive magnetic toner. This supports a conductive magnetic developer on a cylindrical conductive sleeve with magnetism inside.
This is brought into contact with an electrostatic image and developed.
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, 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, 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. This makes it difficult to implement in practice. 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. 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, 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 on the toner holding member.
A phenomenon is observed in which an image developed by a portion that has not been used at all during size copying has a lower image density than an image developed by a portion that has been used. 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. 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 a toner has good chargeability and a clear image can be obtained. That is, the present invention provides a method for developing an electrical latent image using triboelectrically charged one-component insulating toner, which is a member that imparts a triboelectric charge to the toner, and a member that imparts a triboelectric charge to the developing section. The present invention provides a developing method in which at least a portion or the entire surface layer of a developer carrier, which is a member for conveying toner, contains an aliphatic fluorine-containing compound. 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. 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, 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 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 an aliphatic fluorine compound approximately 10μ thick. By rotating the nonmagnetic cylinder 4b having the layer 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 applied onto the nonmagnetic cylinder surface, and the cylinder is rotated in the same direction as the electrostatic image holding surface 1. Friction between the surface and the toner particles gives the toner particles a charge of opposite polarity to the electrostatic image charge. Further, an iron doctor blade 10 is placed close to the cylindrical surface (at a distance of 50μ to 500μ),
By arranging it to face one magnetic pole (the S pole in the figure) of the multipolar permanent magnet 9, the thickness of the toner layer is controlled to be thin (30 μm to 300 μm) and uniform. 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. doctor blade 1
Instead of iron, 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 developer carrier such as a sleeve, which is a member that contacts the developer powder and applies the charge necessary for development. Examples of the aliphatic fluorine-containing compounds used in the present invention include polytetrafluoroethylene, polytrifluorochloroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinyl fluoride, and ethylene-tetrafluoroethylene copolymer. Polymers containing fluorine such as polymers, or aliphatic compounds having polar groups such as ether groups, carboxyl groups, sulfone groups, amino groups, amide groups, quaternary ammonium groups, and hydroxyl groups at the end of the molecular chain or in the molecular chain. Examples include fluorocarbons and aliphatic fluorochlorocarbon compounds. In the present invention, the aliphatic fluorine-containing compound described above is contained in at least the surface of the member that imparts a triboelectric charge to the toner. Preferably, it has a layer of a group fluorine-containing compound formed thereon. In order to form a layer of an aliphatic fluorine-containing compound in this manner, it may be dispersed or dissolved in a well-known solvent, or dispersed or dissolved together with a suitable binder, and the resulting solution may be applied to the recording substrate. . In some cases, heat treatment is also preferred.
By forming layers in this way,
A uniform coating layer is obtained. Furthermore, in the present invention, other suitable polymers or dyes may be added to the aliphatic fluorine-containing compound for the purpose of improving various physical properties such as adhesion to the triboelectric charging member substrate, coating properties, and durability, or for other purposes. pigments, plasticizers,
Conductive additives such as anti-aging agents, carbon black, fine metal powder, ionic surfactants, glass fibers,
A reinforcing member such as a stainless filament, hydrophobic colloidal silica, etc. can be added. The one-component insulating toner of the present invention is composed of a binder resin and additives such as a colorant, a charge control agent, a fixing aid, and an anti-caking agent, and known materials can be used for each of them. For example, the binder resin includes monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene;
Styrene-p-chlorostyrene copolymer, 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-α-methyl chloromethacrylate Copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-
vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer,
Styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-
Styrenic copolymers such as maleic ester copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin,
Polyvinyl butyral, polyamide, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. alone or in combination. It can be used as 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 a magnetic developer powder, ferromagnetic elements and alloys and compounds containing these, such as iron such as magnetite, hematite, and ferrite, cobalt, nickel, manganese, and other alloys and compounds, may be used as the magnetic powder. Substances conventionally known as magnetic materials such as ferromagnetic alloys can be contained. As in the present invention, when an aliphatic fluorine-containing compound is contained in at least a part or the whole of the surface layer of the developer carrier, which is a member that imparts a triboelectric charge to the one-component insulating toner, compared to a case where the aliphatic fluorine-containing compound is not contained. A clear image with high image density is always obtained even when making multiple copies, and when a large original is copied after many small originals are made using single-component toner, the image density becomes lighter in the wider area. The phenomenon becomes almost unrecognizable. Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 Dispersion consisting of 3 parts by weight of polytetrafluoroethylene (trade name, Hablon L-2, manufactured by Daikin Industries, Ltd.), 3 parts by weight of polyurethane (trade name, Bandex, manufactured by Dainippon Ink Chemical Co., Ltd.), and 100 parts by weight of toluene. A mixed layer of polytetrafluoroethylene and polyurethane with a thickness of approximately 10 μm was formed on the surface of a 50 mmφ stainless steel cylinder using a liquid, and this cylinder was used as a sleeve. On the other hand, 100 parts by weight of zinc oxide, styrene-
A mixture consisting of 20 parts by weight of butadiene copolymer, 40 parts by weight of n-butyl methacrylate, 120 parts by weight of toluene, and 4 parts by weight of 1% rose bengal methanol solution was dispersed and mixed in a ball mill for 6 hours. This was applied to a 0.05mm thick aluminum plate with a dry coating thickness of 40μ.
A zinc oxide-binder type photoreceptor was prepared by applying the resin using a wire bar and evaporating the solvent with hot air. This photoreceptor was subjected to -6KV corona discharge to uniformly charge the entire surface, and then the original image was irradiated to form an electrostatic latent image. This latent image is formed by using the cylinder as a sleeve, with a sleeve surface magnetic flux density of 700 Gauss as shown in FIG.
A fixed sleeve rotating magnet (the peripheral speed of the sleeve is the same as that of the drum, but the direction of rotation is opposite) with a distance between the ear cutting blade and the sleeve surface of 0.2 mm was set at a distance of 0.25 mm between the photosensitive drum surface and the sleeve surface, and the sleeve was AC of 200Hz600V and -150V
By applying a DC bias of The powder image was developed using a developer consisting of parts by weight, and then the powder image was transferred while irradiating a direct current corona of -7 KV 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 fixing was performed 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. Furthermore, after making 1000 copies of A4 size paper, I made copies of B4 size paper, but there was hardly any phenomenon in which the image density became lighter in the wider area. Example 2 Using a polytetrafluoroethylene dispersion solution (product name: Polyfron Tough Coat Enamel, manufactured by Daikin Industries, Ltd.), a polytetrafluoroethylene mixture layer with a thickness of approximately 15 μm was formed on the surface of a 50 mmφ stainless steel cylinder, and After firing at 300°C, this cylinder was used as a sleeve. The insulating surface 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 to 7KV at the same time. After performing alternating current corona discharge, the entire surface is uniformly exposed to form an electrical latent image on the surface of the photoreceptor. As shown in Fig. 2, the sleeve having the polytetrafluoroethylene coating layer was fixed to a sleeve rotating magnet with a sleeve surface magnetic flux density 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). The rotation direction is opposite) type developing device was set at a distance of 0.25 mm between the photosensitive drum surface and the sleeve surface, and the sleeve was applied with 200Hz600V.
AC and DC bias of 150 V were applied, and the film was developed using a developer consisting of 100 parts by weight of styrene-butyl acrylate-butyl maleate copolymer, 50 parts by weight of magnetic powder, and 0.4 parts by weight of hydrophobic colloidal silica. Next, the powder image was transferred while irradiating a 7 KV DC corona from the back side of the transfer paper to obtain a duplicate image.
The remaining developer on the photosensitive drum was removed using a blade cleaner, and fixing was performed using a commercially available plain paper copying machine (trade name: NP-5000, manufactured by Canon). Almost the same results as in Example 1 were obtained.
Furthermore, substantially similar results were obtained using polytrifluorochloroethylene and tetrafluoroethylene copolymers. Example 3 1 part by weight of nonionic fluorine-based surfactant (product name, Megafac F-1440, manufactured by Dainippon Ink and Chemicals), polyester resin (product name, Vylon-200,
A stainless steel cylinder with a diameter of 50 mm is immersed in a solution consisting of 5 parts by weight (manufactured by Toyobo Co., Ltd.) and 100 parts by weight of methyl ethyl ketone, then pulled up and dried to form a coating of about 15 μm on the surface of the cylinder.
The same procedure as in Example 1 was carried out except that a thick coating layer was obtained and the cylinder was used as a sleeve. Good results were obtained similarly to Example-1. Comparative Example 1 A good image was obtained when the same procedure as in Example 1 was performed except that polytetrafluoroethylene was not applied to the sleeve surface, but when 1000 copies were made using A4 size paper, After that, when I made a copy in B4 size, the image density in the wider area became noticeably lighter. 【table】

[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 roll, 10...Doctor blade, 11
...Insulating magnetic toner.

Claims (1)

[Claims] 1. In a method of developing an electrical latent image using triboelectrically charged one-component insulating toner, a member that imparts a triboelectric charge to the toner and conveys the triboelectrically charged toner to a developing section. A developing method characterized in that at least a part or the whole of the surface layer of a developer carrier, which is a member for the development, contains an aliphatic fluorine-containing compound.