JPS5834829B2 - Electrophotographic developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming method for converting an electrostatic charge image into a visible image, and particularly relates to an image forming method using a developer made of an insulating magnetic toner not mixed with a carrier.

Methods for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. can be broadly divided into liquid development methods that use a developer in which various pigments and dyes are finely dispersed in an insulating organic liquid; For example, the cascade method, the magnetic brush method, or There are dry developing methods, such as a bristle brush method, an impression method, a powder cloud method, and an oven chamber method, which use a developer made only of the above-mentioned toner without mixing a carrier. The present invention relates to a developing method using a developer consisting only of toner without mixing carrier.

Of the developing methods that use a developer consisting only of toner with no carrier mixed in, the bristle brush method develops by impregnating a soft animal hair brush with toner and stroking it over an electrostatic image; rather, the hair is used as a carrier. It is used as a.

However, this method has the disadvantage that the bristle brush is easily affected by humidity and it is difficult to control the electrical characteristics.

In the impression method, toner is supplied onto a roller covered with velvet or the like, and an electrostatic charge image is developed while applying a bias voltage to the roller and photosensitive plate, so it is advantageous for obtaining wide-area or continuous-tone images. However, like the bristle brush method, it has the disadvantage of being easily affected by humidity.

In the powder cloud method, toner is sprayed from a thin nozzle between developing electrodes placed close to the electrostatic image surface, and the electrostatic image is developed using the charging of toner particles due to the triboelectric effect. The image density can be controlled by the polarity and magnitude of the bias voltage applied between the image support and the electrostatic charge image support, but the edge effect is relatively large, making it impossible to obtain continuous tone images, and the structure of the device is In addition to being complex, this method has the disadvantage that toner pools are likely to form on the developing surface, which may cause local image inversion.

Furthermore, since the open chamber method is the same as the powder cloud method described above except that it does not use a developing electrode, it has the same drawbacks, and this method also has a large edge effect, making it unsuitable for obtaining continuous tone images. It has the following drawback.

In order to improve the shortcomings of these developing methods, so-called MagneDry develops electrostatic images using conductive toner with magnetism and a magnetic brush with a relatively simple metal sleeve on its surface. There is a developing method called method.

Because the toner itself is conductive, it is possible to develop using only one type of toner regardless of whether the polarity of the electrostatic charge image is positive or negative, and it also provides relatively good continuity in gradation. Although it has the advantage of being able to obtain a toned image, since the toner itself is conductive, the image will be distorted if the toner image is electrostatically transferred onto other substrates such as paper after development. Therefore, it is difficult to obtain a transferred image, and therefore, it has the disadvantage that it is difficult to use it only when directly fixing an image on a photosensitive plate or photosensitive paper on which an electrostatic charge image is formed.

On the other hand, U.S. Patent No. 3 describes a method of transferring magnetic toner using magnetic force to obtain good images without being affected by the atmosphere.
No. 239465.

However, this method is undesirable because the lines of magnetic force of the transferred magnetic field are curved, resulting in distortion of the transferred image.

A developing method using a carrier belt, which is a developing method that does not use carrier particles, has also been disclosed, but this is not preferred in terms of image density and stability and high speed.

The present invention was made based on the above-mentioned vehicle shape.
The objects of the present invention are that the developing operation is not affected by humidity, that good continuous tone images can be obtained, that the structure of the apparatus used is extremely simple, that the developing efficiency is high, and that It is an object of the present invention to provide an image forming method in which an unfixed toner image can be transferred well even when an electrostatic transfer method is applied, and a well-fixed image can be formed by fixing with a hot roller.

The inventor has discovered that the above purpose is to obtain a resin component and a resin component 100.
A magnetic toner containing 20 to 70 parts by weight of a ferromagnetic material, the resin being insulating and containing at least 25% by weight of a styrene component, is used as an electrostatic image developer without being mixed with a carrier. It has been found that an image forming method can be used in which an electrostatic charge image on a substrate is developed by a brush method, the resulting toner image is transferred onto another substrate, and then an image is formed by fixing with a hot roller.

That is, by using the toner according to the present invention,
Electrostatic charge images can be developed well using a developing device with a simple structure, such as that used in a magnetic brush method, which uses a conventional carrier mixed without mixing a carrier.
Furthermore, an unfixed toner image obtained by development can be transferred onto another substrate with good performance by a transfer method.

Good fixed images can be produced by heat roller fixing, which has good thermal efficiency and is suitable for high speeds.

Furthermore, as a developing device, a magnetic brush method with a simple structure can be used (and since there is no need to use a carrier, stirring devices such as scraping plates or stirring tools can be used to stir the developer in the developing device). Also, by not using a carrier, the toner concentration in the developing device is always kept constant, so there is no need to provide a toner concentration detection device to precisely adjust the amount of toner replenishment. .

The fixing device uses a heat roller method rather than a solvent vapor method or a non-contact heating method, so it has excellent thermal efficiency, allowing the device to be faster and more compact, and therefore has a smaller structure than devices for conventional image forming methods. In addition to being simple, it has the excellent advantage that, for example, a copying machine incorporating an image forming apparatus consisting of a developing device and a fixing device can be made extremely compact as a whole, and its manufacturing cost can also be reduced. have

The toner used in the present invention is mainly composed of a resin component, a colorant, and a particulate ferromagnetic material, and various thermoplastic resins are used as the resin component to impart insulation properties to the toner.

Advantageously used thermoplastic resins include, for example, styrenes such as styrene and parachlorostyrene, vinylnaphthalene, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, and the like. vinyl esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloro-ethyl acrylate,
Esters of α-methylene aliphatic monocarboxylic acids such as phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, For example, vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl impropenyl ketone, N-vinylpyrrole, N-vinylcarbasol, N-vinyl Indore, N.
- A homopolymer obtained by polymerizing monomers such as N-vinyl compounds such as vinylnaphrine, a copolymer obtained by copolymerizing two or more of these monomers, or a mixture thereof, or a tonabarosin-modified phenol-formalin resin , non-vinyl resins such as non-vinyl thermoplastic resins such as oil-modified epoxy resins, polyurethane resins, cell opening resins, and polyether resins, or mixtures of these and vinyl resins as described above. .

Among these resins, especially vinyl resins and 1 to 20
White glass transition point above ℃, about 1000 to 5000
Those having a weight average molecular weight of 0.00 are effectively used in the toner of the present invention.

To fix the developed toner image using a heated roller,
When using a resin whose main component is a styrene resin, it is desirable that the styrene component in the resin component used is at least 25% by weight based on the total weight of the resin.

The reason for this is that the releasability of the toner (with respect to the fixing roller) is closely related to the amount of styrene component present, and as the styrene component is reduced, the releasability of the toner with respect to the fixing roller tends to decrease. be.

Any suitable pigment or dye can be used as the coloring agent.

For example, carbon black, nigrosine dye, aniline blue, calcooil pur - chrome yellow, ultramarine pur -, typhon oil red, quinoline yellow, methylene blue chloride, phthalocyanine flu, malachite green offsalate, lamp black, rose bengal and their Mixtures are used and these need to be included in the toner in an amount sufficient to color the toner so that it can be developed to form a visible image, for example when carbon black is used; It is desirable to add about 1 to 10 parts by weight per 100 parts by weight of the resin component of the toner.

Among colorants, carbon black is particularly effectively used, but oxidized carbon black itself has charge control properties. Since it is not necessary to contain it, it can be used more advantageously.

It should be noted that since carbon black has conductivity, it is undesirable to add too much since it will reduce the insulating properties of the toner if it is added in too much.

Particulate ferromagnetic materials include materials that are extremely strongly magnetized in the direction of magnetic fields, such as alloys or compounds containing ferromagnetic elements such as ferrite and magnetite, as well as iron, cobalt, and nickel, and ferromagnetic elements. Alloys that do not contain manganese and copper but become ferromagnetic by proper heat treatment, such as alloys called Heusler alloys that contain manganese and copper, such as manganese-steel-aluminum or manganese-copper-tin, or chromium dioxide. is advantageously used.

When these ferromagnetic substances are contained in the toner, it is desirable that the average particle size is approximately 0.1 to 1 micron, and the amount contained in the toner is approximately 20 to 70 parts by weight per 100 parts by weight of the resin component. It is desirable to do so.

Note that since ferromagnetic materials generally have electrical conductivity, in order to maintain the insulating properties of l.ner, as in the case of carbon black, it is not desirable to include them in too large a quantity.

Various other toner additives can be added to the toner used in the present invention, if necessary.

For example, certain dyes and pigments can be added as charge control agents to control the charge of the toner.

As these charge control agents, for example, Japanese Patent Publication No. 41-2
Feuette Spartu HBN (Color Intex, %26150) as described in Publication No. 427,
Alcohol-soluble nigrosine (color index/1
6.50415), Sudan Chief Schwarz BB (
Color Index/l6L26150), Brilliant Spirit Schwarz TN (manufactured by Bayer), Zabon Schwarz X (manufactured by Hoechst), Ceres Schwarz B)
G (manufactured by Bayer), Chromogenschwarz ETCO (
Examples include dyes such as Color Index A14645), Azo-Oil Black R (8) (manufactured by National Aniline), and metal-containing dyes such as phthalocyanine blue.

Further, in order to improve the compatibility of these charge control agents with the resin component, they can be added in the form of salts formed with higher fatty acids, or a compatibility improver can be added separately.

Toners for use in image formation in which the fixing process is performed using a heated roller contain substances that have a releasing effect on the fixing roller, such as fatty acids such as cadmium stearate, barium stearate, zinc oleate, and cobalt palmitate. Metal salts, relatively low molecular weight polyethylene or polypropylene, higher fatty acids having 28 or more carbon atoms, natural or synthetic paraffins, etc. can be added, and the resin component is relatively brittle. A plasticizer or the like can be added to modify this.

To manufacture the toner used in the present invention, conventional toner manufacturing methods can be applied as they are.

For example, various toner additives such as a resin component, a colorant, a particulate ferromagnetic material, and a charge control agent used in combination with these are premixed using a ball mill or the like to uniformly mix each component. The mixture is dispersed, then kneaded using heated rolls, cooled and pulverized.

Next, in order to obtain a toner with a desired particle size, it is classified as necessary, and for example, in order to use it in a magnetic brush method, it is
A toner having an average particle size of 15 microns is produced.

The particle size of the toner used in the present invention varies depending on the purpose of use, the type of electrostatic image to be developed, the structure of the developing device, etc., but it is generally desirably about 5 to 20 microns, and the most suitable size depends on the purpose of use. Any compatible particle size can be used.

Since the toner used in the present invention is used without being mixed with a carrier, it is desirable that the toner has a spherical shape as much as possible in order to improve the fluidity of the toner and prevent agglomeration.

Further, it is desirable that toner particles with relatively small particle sizes are not mixed, and the particle sizes are uniform.

In order to produce toner particles having such a spherical shape, the pulverized fine toner powder produced according to the method described above is further sprayed into hot air to instantaneously melt the surface of each toner particle. It is preferable to make the surface of the toner particles spherical by surface tension.

In addition, if the particulate ferromagnetic material is exposed in a bare state on the surface of the toner particles, the charging characteristics of the toner particles tend to deteriorate. Therefore, before incorporating the particulate ferromagnetic material into the toner, It is desirable to coat the surface with a higher fatty acid.

Examples of higher fatty acids that can be used for this purpose include stearic acid, palmitic acid, and oleic acid. The coating can be easily applied by dipping the body.

Further, toner particles can also be produced by using a core made by dispersing fine particulate ferromagnetic material in a resin, and coating the surface of the core with a toner component whose main components are a resin component and a colorant.

To develop an electrostatic image using the above toner without mixing carrier, a developing method such as a bristle brush method or a magnetic brush method can be used as is.

However, the developing method that yields the best results is when only toner is used without mixing carrier, and when a magnetic brush type developing device is used.

The magnetic brush method used in this case is particularly effective when a so-called sleeve is provided on the circumferential surface of a cylindrical magnet, which is a cylinder made of a conductive non-magnetic material. Particularly effective is one consisting of an assembly of a plurality of magnets arranged with sequentially different polarities in different directions.

It is desirable that the magnet and the sleeve be configured to move relative to each other. Specifically, for example, the sleeve may be fixed and the internal magnet rotated, or the magnet may be fixed and the sleeve rotated. Either method can be used.

Of course, both can also be rotated together in opposite directions.

When a developing method using a sleeve and a magnet as described above is applied, since the toner used in the present invention contains a ferromagnetic substance inside the toner particles, the toner particles are magnetically attracted onto the sleeve surface by the magnet. According to the relative movement of the magnet to the sleeve, the toner particles attracted onto the sleeve move on the sleeve surface while rotating.
The friction created between the sleeve surface and the toner particles charges the toner particles with an appropriate charge.

Due to the absence of carrier, the toner on the sleeve surface forms a relatively thin layer covering the sleeve surface.

At this time, in order to control the thickness of the toner layer on the sleeve surface and to ensure uniform development, it is desirable to appropriately cut the toner tips, which are uneven on the surface of the toner layer, using, for example, a regulating plate.

Note that metals such as aluminum and brass can be used as the sleeve, and when such a sleeve is used, good results can be obtained by incorporating a charge control agent into the toner.

Furthermore, by not containing a charge control agent in the toner and applying corona discharge to the toner layer formed on the sleeve surface at an appropriate position before reaching the development position, it is possible to impart charge to the toner particles. According to this means, by selecting the polarity of the corona discharge, it is possible to impart charges of either positive or negative polarity to the toner.

Further, by providing a thin layer containing a charge control agent on the surface of the sleeve, it is possible to impart a good charge to the toner without including the charge control agent in the toner.

The layer containing the charge control agent provided on the sleeve surface may be made of a conductive resin or a resin that does not significantly reduce the conductivity of the entire sleeve surface even if it is not conductive, such as a melamine resin such as methylmelamine resin. Alternatively, use polyester resin such as nylon 6 as a binder,
A toner containing various charge control agents dispersed therein, which can be added to the toner as described above, can be effectively used.

The layer is preferably non-hygroscopic and has high mechanical strength, and its thickness is approximately 10 to
A thickness of about 20 microns is sufficient.

The charge control agent contained in the layer has a property of charging the toner to a polarity opposite to that of the electrostatic image to be developed.

In addition to containing a charge control agent in the layer, the toner may also contain a charge control agent having a charge imparting polarity different from that of the charge control agent contained in the layer.

In the developing device to which the present invention is applied, there is no carrier in the developer, only toner, so it is only necessary to replenish toner in the amount consumed for development. It also has an extremely simple structure as it does not require the use of complicated devices such as conventional toner concentration detection devices to measure the mixing ratio of toner and carrier, and there is no need to stir the toner in the developing device. Moreover, it is possible to use a developing device that is easy to maintain.

The electrostatic charge image that can be formed by applying the method of the present invention may be formed not only by electrophotography using a photoconductor but also by electrostatic recording on an insulating layer. An electrostatic charge image formed by any method can be effectively formed.

Note that the unfixed toner image developed by the method of the present invention is transferred onto another base material such as paper, and upon transfer, a good transferred image can be obtained that is exactly the same as the toner used in the conventional transfer method. be able to.

Regarding fixing, heat roller fixing makes it possible to obtain a fixed image firmly adhered to the substrate with good releasability without the image being attached to the surface of the heat roller.

Next, the present invention will be illustrated by examples, but the embodiments of the present invention are not limited thereto.

In the examples, the number of copies is expressed by weight unless otherwise specified.

Example 1 70 parts of Picolastic D-100 (manufactured by Esso Petrochemical Co., Ltd., styrene resin), 30 parts of Pentacy) P-406 (manufactured by Nippon Reichhold, natural resin-modified pentaerythritol resin), and Peerless 155 (Columbia) 5 parts of Nigrosine Base EX (manufactured by T!J End Kagaku Co., Ltd.), and 20 parts of magnetite (Fe203) with an average particle size of 1 micron soaked in a trichlorethylene solution of oleic acid. The mixture was mixed and subjected to a ball mill for about 24 hours, then kneaded using a hot roll, cooled, crushed, and classified to produce a toner having an average particle size of about 13 to 15 microns.

Next, a commercially available zinc oxide photosensitive paper for transfer that can be used repeatedly (
Copy master for Ubitx, manufactured by Konishiroku Photo Industry Co., Ltd.)
After forming an electrostatic charge image on the surface of the toner according to an ordinary electrophotographic method, a fixed cylindrical magnet with alternately arranged different magnetic poles is used as a developing device, as shown in FIG. The image was developed using a device consisting of a sleeve configured to rotate around its outer periphery, and then transferred to plain paper in accordance with a conventional method and fixed with a hot roller. A good image was obtained.

In FIG. 1, 1 indicates a toner container, 2 indicates toner, and 3 indicates the entire toner supply device for an electrostatic image surface.

4 is a brass sleeve, 5 is a permanent magnet, 6 is a regulation plate, 7
8 indicates a photosensitive layer that moves as shown by an arrow, 8 indicates a conductive base material holding the photosensitive layer, and ▪ indicates a single layer of toner.

Now, when the sleeve 4 starts operating to develop the electrostatic latent image on the photosensitive layer 7, the sleeve 4 adheres to the sleeve 4 in the toner container 1 due to the relative movement with the magnet 5. The toner 2 forms a uniform layer 1 on the sleeve 4 by the regulation plate 6 and contacts the surface of the photosensitive layer 70 one after another, where the toner is electrostatically attracted in proportion to the intensity of the charge of the electrostatic charge image. and development is performed.

Incidentally, when the above-described development, transfer and fixing operations were repeated, good images were always obtained.

Example 2 80 parts of Picolastic E-125 (manufactured by Esso Petrochemical Co., Ltd., styrene resin), 20 parts of Eslec BL-8 (manufactured by Tanesui Chemical Co., Ltd., polyvinyl butyral resin), 10 parts of Peerless 155, and average particle Ferrite with a diameter of 1 micron (
The mixture was mixed with 30 parts of Fe203) and subjected to a ball mill for about 24 hours, then kneaded using hot rolls, cooled, and pulverized.

The obtained powder was then atomized in hot air, dried, and classified to produce a toner consisting of spherical particles with an average particle size of 13 to 15 microns. After forming an electrostatic charge image using paper and performing the same operation, the toner is used as a developing device using a rotating cylindrical magnet with alternately arranged different magnetic poles as shown in FIG. It is developed using a device consisting of a brass sleeve or the like having a layer containing a charge control agent on its surface, rotating in the opposite direction to the cylindrical magnet at its outer periphery, and then applied to plain paper in a conventional manner. After transferring and fixing with a heat roller, a good image was obtained.

All numbers in FIG. 2 indicate members having the same function as the same numbers in FIG. 1.

Note that the layer containing the charge control agent provided on the surface of the sleeve is formed by applying the following composition and drying it to a dry film thickness of about 10
It is measured in microns.

In this example as well, when the development and transfer operations were repeated, good images were always obtained.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are cross-sectional views showing developing devices used in Example 1 and Example 2, respectively. 1... Toner container, 2... Toner 3.
...Toner supply device, 4...Sleeve,
5...Permanent magnet, 6...Regulation plate, 7.
... Photosensitive layer, 8 ... Conductive base material, C...
...Corona discharge device

Claims (1)

[Claims] 1 Resin component and 20 to 70 parts per ioo weight part of the resin component
A magnetic toner containing parts by weight of a ferromagnetic material, the resin being insulating and containing at least 25% by weight of styrene fraction, is used as an electrostatic image developer without being mixed with a carrier and applied to a substrate by a magnetic brush method. An image forming method in which an image is formed by developing an electrostatic charge image, transferring the resulting toner image onto another substrate, and then fixing the toner image with a heated roller.