JPH0473584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device that develops an electrical latent image formed in electrophotography, electrostatic recording, etc. with an insulating toner to obtain a visible image.

Conventionally, as an electrophotographic method, U.S. Patent No. 2297691
specification, Japanese Patent Publication No. 42-23910 (U.S. Patent No.
A number of methods are known, as described in Japanese Patent Publication No. 3666363) and Japanese Patent Publication No. 43-24748 (U.S. Pat. No. 4071361), but generally they utilize photoconductive substances, An electrical latent image is formed on the photoreceptor by various means, then the latent image is developed using toner, and if necessary, the toner image is transferred to a transfer material such as paper, and then heat, pressure, or a solvent is used. Copies are obtained by fixing with steam or the like.

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 two-component 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. It supports a conductive magnetic developer on a cylindrical conductive sleeve with a magnet inside;
This is developed by bringing it into contact with an electrostatic image. At this time, a conductive path is formed between the recording body surface and the sleeve surface by toner particles in the developing section.
An electric charge is applied to the toner particles from the sleeve through this conductive path, and the toner particles adhere to the image area due to the Coulomb force between the sleeve and the image area of the electrostatic image 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, Japanese Patent Application Laid-Open No. 1983-94140 (West German Patent No. 2704361) describes a developing method using dielectric polarization of toner particles. It is shown. 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 method involves applying an extremely thin layer of insulating magnetic toner on a sleeve, triboelectrically charging it, and then placing it in close proximity to the electrostatic image under the action of a magnetic field, facing it without contact, to charge the toner electrostatically. The image is developed by flying it towards the image.

According to this method, by applying an extremely thin layer of insulating magnetic toner onto the sleeve, the chances of contact between the sleeve and the toner are increased, and sufficient frictional electrification is possible.The toner is supported by magnetic force,
Furthermore, by moving the magnet and toner relative to each other, the toner particles are disaggregated and are sufficiently rubbed against the sleeve, and the toner is supported by magnetic force and is opposed to the electrostatic image without coming into contact with it. Excellent images can be obtained because background fog is prevented by developing the image.

However, even with this method, the applicability of the toner onto the sleeve is likely to be affected by environmental conditions, and the toner is rarely stirred, and in particular, the extent to which it moves from side to side on the sleeve is extremely small. There are various problems.

For example, when the fluidity of the toner is reduced due to high or high temperatures, the agglomeration of the toner cannot be sufficiently dissolved by magnetic force, resulting in a decrease in image quality and image density. .

In addition, when the humidity is low, highly triboelectrically charged toner adheres firmly to the sleeve, so if the sleeve is rotated repeatedly, the toner coating layer on the sleeve becomes uneven, which also affects the image. .

In addition, when a large number of originals with unevenly distributed image areas are photographed in succession, the areas that are not used for development at all,
The next time a copy is made, development with reduced image density can be seen. In addition, if the triboelectric charge amount of insulating toner is too small, fogging will occur, and if it is too large, a strong electric field will be required for development. There must be. However, this has the disadvantage that the selection of materials contained in the insulating toner is severely restricted.

In particular, the present invention is directed to a developing device used in a developing method in which, as described above, an insulating toner is thinly applied onto a toner carrier, this is triboelectrically charged, and this toner is transferred to an electrical latent image for development. It is related to.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a developing device that can improve the coating properties of toner onto a toner carrier and obtain a stable and uniform thin layer of insulating toner on the toner carrier. .

Another object of the present invention is to provide a developing device that exhibits stable charging properties by improving the coating properties of the toner described above.

A further object of the present invention is to provide a developing device in which the image density hardly decreases even when a large number of copies are made.

Furthermore, another object of the present invention is to provide an excellent toner image in a low electric field even with an insulating toner having a relatively wide range of triboelectric charges, thereby easing the limitations on materials for insulating toners. It is an object of the present invention to provide a developing device that can perform the following steps.

Specifically, the present invention applies a thin layer of insulating toner to a toner carrier, triboelectrically charges the insulating toner through contact with the toner carrier, and converts the triboelectrically charged insulative toner into an electrical latent image. In a developing device that performs development by transferring toner, a part or whole of the surface layer of the toner carrier contains a pyridine ring, a benzene ring,
It contains an electron-donating resin having a donor group selected from the group consisting of a naphthalene ring, an anthracene ring and an imidazole ring, and a primary, secondary or tertiary amino group, in whole or in part, the electron-donating resin, The present invention relates to a developing device characterized by the presence of a compound having electron-accepting properties or a halogen.

Here, a part of the surface layer of the toner carrier contains an electron-donating resin when it is coated with a very thin layer of resin, for example, 100 to 200 Å or less.
This means that the resin does not completely cover the surface layer, but the polymer is scattered or forms a film with gaps. Even in such a case, sufficient effects can be obtained if the distance between the polymer dots or the gap between the films is on the order of Å.

The apparatus 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 a developing device according to the present invention can be applied, but the present invention is not limited thereto.

1 is an electrostatic image holder, which is formed as a photosensitive drum containing a photoconductive layer, and can be used with or without an insulating layer on its surface, and of course is not limited to the drum shape. Sheet-like or belt-like products are 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 electrostatic image holder 1. A developing device 4 has a toner carrier 4a, and forms a toner particle image in accordance with the electrostatic image on the electrostatic image holder 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.
It is also possible to adopt a so-called electrostatic image transfer method, in which the electrostatic image on the electrostatic image carrier 1 is temporarily transferred to another image carrier, 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 electrostatic image holder 1 after transfer, so that the electrostatic image holder 1 can be reused.

In the present invention, an insulating toner is applied thinly onto a toner carrier, triboelectrically charged, and the toner is transferred to an electrical latent image formed on an electrostatic image carrier 1, thereby making the latent image visible. This relates to a type of developing device, one embodiment of which is shown in FIG. In FIG. 2, 1 is an electrostatic image holder, 4a is a toner carrier made of a non-magnetic sleeve, 4b is a multipolar permanent magnet provided in the toner carrier, a is a toner container, and 10
Reference numeral 11 indicates an iron doctor blade, and 11 indicates an insulating magnetic toner contained in the toner container. In the developing process, the electrostatic image holder 1 rotates in the direction of the arrow, and the toner carrier 4a rotates in the direction of the arrow. The magnet 4b is fixed so as not to rotate. On the surface of the toner carrier 4a, there is provided a coating layer 4c of about 20 μm thick made of an electron-donating resin containing an electron-accepting compound or halogen.

In this device, by rotating a toner carrier 4a made of a non-magnetic sleeve having a coating layer 4c in the same direction as the electrostatic image carrier 1, an insulating toner 11 sent from a toner container 9 is transferred to the toner carrier. It is applied onto a cylindrical surface, and friction between the cylindrical surface and the toner particles gives the toner particles a charge of opposite polarity to the electrostatic image charge. Furthermore, an iron doctor blade 10 is placed close to the cylindrical surface (with a spacing of 50 μm).
~500 μ), by arranging it opposite to one magnetic pole (in the figure, the S pole) position of the multipolar permanent magnet 4b.
The thickness of the toner layer is controlled to be thin (30μ to 300μ) and uniform. By adjusting the rotational speed of the toner carrier 4a, the surface speed and preferably the internal speed of the developer layer are made to be substantially the same as, or close to, the speed of the electrostatic image carrier. As the doctor blade 10, a permanent magnet may be used instead of iron to form opposing magnetic poles. Further, in the developing section, an alternating current bias may be applied between the developer carrier and the electrostatic image holder.

The electron-donating resin coating layer 4c may be provided on the entire surface layer of the toner carrier, or may be provided on a portion thereof. Further, the compound having electron-accepting properties or the halogen may be present in the entire resin or in a part thereof.

The electron-donating resin has a donor group with a low ionization voltage selected from the group consisting of a pyridine ring, a benzene ring, a naphthalene ring, an anthracene ring, and an imidazole ring in the side chain of the polymer, and a first, second, or A resin having tertiary amino groups is used. Specifically, styrene monomer and
Copolymers with nitrogen-containing monomers such as dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropylamide acrylate, 4-vinylpyridine, 2-vinylpyridine, vinylimidazole or dimethylaminostyrene may be mentioned. Further, the surface layer of the toner carrier may contain other resins, such as polyethylene, poly-p-chlorostyrene, polyvinyltoluene, styrene-butadiene copolymer, styrene-acrylic. Acid copolymers, polymers or copolymers of styrene or its substituted products such as styrene-maleic anhydride copolymers; polyester resins, acrylic resins, xylene resins, polyamide resins, ionomer resins, furan resins, ketone resins, Terpene resin, phenol-modified terpene resin, rosin, rosin-modified pentaerythol ester, natural resin-modified phenolic resin, natural resin-modified maleic acid resin, coumaron indene resin, maleic acid-modified phenolic resin, alicyclic hydrocarbon resin, petroleum resin , cellulose acetate phthalate, methyl vinyl ether-maleic anhydride copolymer, starch graft polymer, polyvinyl butyral, polyvinyl alcohol, polyvinylpyrrolidone, chlorinated paraffin, wax, fatty acid, etc. can be used alone or in combination.

Examples of compounds having electron-accepting properties include cyano compounds, such as 7,7,8,8-tetracyanoquinodimethane, 2-methyl-7,7,8,8
-tetracyanoquinodimethane, 2,5-dimethyl-7,7,8,8-tetracyanoquinodimethane,
2,5-diethyl-7,7,8,8-tetracyanoquinodimethane, 2-methoxy-7,7,8,8
-tetracyanoquinodimethane, 2,5-dimethoxy-7,7,8,8-tetracyanoquinodimethane, 2-methoxy-5-ethoxy-7,7,8,
8-tetracyanoquinodimethane, 2-methoxydihydrodioxabenzo[e]-7,7,8,8-
Tetracyanoquinodimethane, 2-chloro-7,
7,8,8-tetracyanoquinodimethane, 2-bromo-7,7,8,8-tetracyanoquinodimethane, 2,5-dibromo-7,7,8,8-tetracyanoquinodimethane, 2,5-diaiod-7,
7,8,8-tetracyanoquinodimethane, 2-chloro-5-methyl-7,7,8,8-tetracyanoquinodimethane, 2-bromo-5-methyl-7,
7,8,8-tetracyanoquinodimethane, 2-iodo-5-methyl-7,7,8,8-tetracyanoquinodimethane, 11,11,12,12-tetracyano-2,6-naphthoquino dimethane, 1,1,2,
Examples include 3,4,4-hexacyanobutadiene.

Other electron-accepting compounds include halogen compounds and thiocyanates.

In the present invention, the compound having electron-accepting properties or the halogen may be present in any state such as attached, diffused, or mixed in the whole or part of the outer shell, but in particular, it may be present in the electron-donating resin by doping it. It is preferable to exist in such a state.

In the present invention, the toner carrier for insulating toner is a member capable of applying or auxiliary charge necessary for development by contacting the developer powder, and is mainly a toner holding member such as a sleeve.

In the present invention, the electron-donating resin in which the compound having electron-accepting property or halogen is present,
Contained at least on the surface of the toner carrier,
The member has a layer of an electron-donating resin containing the electron-accepting compound or halogen on the surface of a base material such as a metal such as aluminum, iron, stainless steel, or copper, or an elastic body such as a synthetic rubber or elastomer. Preferably, it is in the form of

To form a layer of an electron-donating resin containing an electron-accepting compound or halogen, the electron-donating resin and the electron-accepting compound or halogen can be mixed with benzene, toluene, xylene, ethyl ether, methyl ethyl ketone, or tetrachloride. It is necessary to dissolve it in a well-known organic solvent such as carbon and apply the solution to the above-mentioned substrate, apply powder coating and bake it, or paste it in the form of a film. By forming the coating layer by such a method, a coating layer having a uniform surface and good adhesion to the substrate can be obtained, resulting in the advantages of the present invention as described later. Furthermore, in the present invention, 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, the electron-donating resin in which the compound having electron-accepting properties or halogen is present is used. Other suitable conductivity aids such as carbon black and fine metal powder, reinforcing members such as glass fiber and stainless steel filament, etc. can be added to the material.

The insulating toner of the present invention includes a binder resin, a colorant,
It consists of additives such as a charge control agent, a fixing aid, and an anti-caking agent, and known materials can be used for all of them. For example, examples of the binder resin include monopolymers of styrene and its substituted products such as polystyrene, poly p-chlorostyrene, and polyvinyltoluene, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, and styrene-vinyl Toluene copolymer, polyamide, epoxy resin,
Polyvinyl petyral, polybumide, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. alone or in combination It can be used as

Furthermore, known dyes and pigments can be used as the coloring agent contained in the insulating toner used in the present invention. For example, various types of carbon black, aniline black, naphthol yellow, molybdenum orange, rhodamine lake, alizarin lake, methyl violet lake, phthalocyanine blue,
Examples include nigrosine methylene blue, rose bengal, and quinoline yellow. Also,
Additives such as charge control agents, fixing aids, and anti-caking agents include carbon black, plasticizers, colloidal silica, and talc. Furthermore, when used as a magnetic toner, the magnetic powder may include ferromagnetic elements and alloys and compounds containing them, such as iron such as magnetite, hematite, and ferrite; alloys and compounds of cobalt, nickel, and manganese; Fine particles of 0.1 to 5 microns of a substance conventionally known as a magnetic material such as a ferromagnetic alloy can be contained. Other insulating toners used in the present invention include magnetic or non-magnetic capsule toners made of a soft material and a hard wall-forming material covering the soft material.

As in the present invention, when an insulating toner contains an electron-donating resin in which a compound having electron-accepting properties or a halogen is present on at least a portion or the entire surface area of a toner carrier such as a sleeve,
Compared to the case without containing it, clear images with high image density are always obtained even when making multiple copies, and the width increases when large originals are copied after many small originals, which is unique to single-component magnetic toner. Development in which the image density becomes thinner in the ivy portions is almost no longer observed.

In addition, since the electron-accepting compound used in the present invention or the electron-donating resin in which halogen is present exhibits relatively low resistance, the insulating toner coated on the toner carrier may be There is little increase in the amount of triboelectric charge even after carrying out a durability test.

In addition, the electron-accepting compound used in the present invention or the electron-donating resin in which halogen is present has an appropriate coefficient of friction for the present invention, and when coated on the surface of a toner carrier member such as a sleeve, A uniform and good toner layer can be formed. As a result, a clear image without fogging can be obtained.

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

Example 1 A stainless steel sleeve with an outer diameter of 50 mm was immersed in a solution consisting of 20 parts by weight of dimethylaminoethyl methacrylate-styrene copolymer (monomer ratio 1:9), 0.1 part by weight of iodine, and 1000 parts by weight of methyl ethyl ketone, then pulled up and dried. Approximately on the sleeve surface
A uniform film with a thickness of 10μ was formed. This sleeve was then attached to a developing device for jumping development having a rotating sleeve and a fixed magnet as shown in FIG.

On the other hand, an electrostatic latent image was formed using a known electrophotographic method, and this latent image was developed using a developing device shown in FIG. At that time, the magnetic flux density on the sleeve surface was set at 700 Gauss, and the distance between the ear cutting blade 10 and the sleeve surface was set at 700 Gauss.
The circumferential speed of the sleeve was the same as that of the photosensitive drum, and the direction was reversed. The distance between the photosensitive drum surface and the sleeve surface was set to 0.30 mm, and an alternating current bias with a frequency of 200 Hz, a negative peak value of -750 V and a positive peak value of +450 V was applied to the sleeve, and dimethylaminoethyl methacrylate-styrene copolymer (monomer ratio 80 parts by weight of quaternized benzyl chloride (1:9), 20 parts by weight of styrene-butyl acrylate copolymer (1:1), 60 parts by weight of magnetic powder,
A developer consisting of 0.3 parts by weight of hydrophobic colloidal silica (9 g of iron powder of 200 to 300 mesh was mixed with 1 g of this toner, and the amount of triboelectric charge was measured using a known measuring method; +30.5 μc/g) It was hot.)
The resulting image was developed using a high-quality paper, and transferred and heat-fixed onto high-quality paper. The image density was 1.3, and a clear reversed image with no fog was formed, which was good. Also,
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 (D _nax ) became thinner in the area where the width increased.

In addition, after a durability test of idle rotation for 4 hours in the developing device, development and transfer/fixing were performed again, but the image density was 1.5 and the amount of triboelectric charge was +32.0 μc/g, resulting in no change in image quality. Good durability was observed.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the coating layer described in Example 1 was not provided on the sleeve surface. Although there was no fog, the image density was significantly lowered to 0.6. . Also, set the image density to 1.0
In order to achieve the above, I increased the developing bias and found that the frequency exceeded 1600Hz and the negative peak value -
It was necessary to apply an AC bias of 1200 V or less plus peak value + 400 V or more.

Example 2 20 parts by weight of dimethylaminostyrene-styrene copolymer (monomer ratio 3:7) and 7,7,8,8
- A stainless steel sleeve with an outer diameter of 50 mm is immersed in a solution consisting of 1 part by weight of tetracyanoquinodimethane and 1000 parts by weight of dimethylacetamide, pulled up and dried to form a uniform coating approximately 6 μ thick on the sleeve surface, It was attached to the developing device shown in FIG.
On the other hand, phthalocyanine blue was added to polyethylene.
Capsule toner (triboelectrification) in which particles obtained by granulating a soft material dispersed at 10% by weight are coated with a quaternized product of benzyl chloride of dimethylaminoethyl methacrylate-styrene copolymer (monomer ratio 1:9). A developer was prepared by mixing 5 parts by weight of charge amount +50.4 μc/g and 5 parts by weight of ferrite powder.

Using this developer and the developing device, an alternating current bias with a frequency of 1600 Hz, a negative peak value of −1200 V, and a positive peak value of +400 V is applied to the sleeve,
When development, transfer, and pressure fixing were carried out in the same manner as in Example 1, the image density was 1.6, and a reversed image with good gradation and no fogging was obtained.

In addition, after a durability test of idling for 1.5 hours in the developing device, development, transfer, and fixing were performed again, but the image density was 1.0, and the amount of triboelectric charge was measured after separating the toner from the developer. However, it was +55.0μc/g, which was a good result.

Comparative Example 2 The same procedure as in Example 2 was carried out except that the coating layer described in Example 2 was not provided on the sleeve surface. The image density was close to 0.5 and there was an electrostatic latent image. Despite this, there were many areas where toner was not attached. Also, set the image density to 1.0
In order to achieve the above, it was necessary to apply an AC bias with a frequency of 4000 Hz or more, a negative peak value of -1650 V or more, and a positive peak value or more.

Example 3 Styrene-butyl acrylate copolymer (monomer ratio 1:1) 7.5 parts by weight, styrene-maleic acid copolymer 7.5 (monomer ratio 1:1) 7.5 parts by weight, diethylaminoethyl methacrylate-styrene copolymer ( Monomer ratio 3:7) 5 parts by weight, bromine 0.1
A stainless steel sleeve with an outer diameter of 50 mm was immersed in a solution consisting of parts by weight of methyl ethyl ketone, pulled up and dried to form a uniform coating with a thickness of about 10 μm on the sleeve surface, and then attached to the developing device shown in FIG. 2.

On the other hand, styrene-methyl methacrylate copolymer (monomer ratio Magnetic capsule toner coated with a mixture of (1:1) and dimethylaminopropylacrylamide (7:3 weight ratio) (triboelectric charge amount +4.7 μc/g)
And so.

Using this capsule toner and the developing device,
Frequency 1200Hz minor speak value on sleeve -
When developing, transferring, and pressure fixing were performed in the same manner as in Example 1 by applying an AC bias of 950 V, plus peak value + 450 V, the image density was 1.1, and a reversed image with good gradation without fogging was obtained. It was done.

In addition, after a durability test of idle rotation for 4 hours in the developing device, development, transfer, and fixing were performed again, but the image density was 1.3 and the amount of triboelectric charge was +8.2 μc/g.
Good results were obtained with little change in image quality.

Comparative Example 3 The same procedure as in Example 3 was carried out except that the coating layer described in Example 3 was not provided on the sleeve surface, but the image density was as low as 0.5 and a fogged image was obtained. .

In addition, in order to make the image density 1.0 or more, the frequency should be 1600Hz or more, the negative peak value -1300V or more,
It was necessary to apply an AC bias with a positive peak value of +700V or more.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an example of a copying device or a recording device to which a developing device according to the present invention can be applied. FIG. 2 is a sectional view of an embodiment of a developing device according to the present invention. 1... Electrostatic image holder, 4... Developing device, 4a...
... Toner carrier (non-magnetic sleeve), 4b ... Multipolar permanent magnet, 4c ... Coating layer, 9 ... Toner container, 10 ... Doctor blade, 11 ... Insulating toner.

Claims (1)

[Claims] 1. Applying a thin layer of insulating toner to a toner carrier,
In a developing device that triboelectrically charges an insulating toner through contact with a toner carrier and transfers the triboelectrically charged insulative toner to an electrical latent image for development,
Part or all of the surface layer of the toner carrier is
an electron-donating resin having a donor group selected from the group consisting of a pyridine ring, a benzene ring, a naphthalene ring, an anthracene ring and an imidazole ring, and a primary, secondary or tertiary amino group; A developing device characterized in that a compound having electron-accepting properties or a halogen is present in whole or in part. 2. The developing device according to claim 1, wherein the compound having electron-accepting properties is a cyano compound.