JPS604953A - Development method - Google Patents

Abstract

PURPOSE:To improve successive use characteristics and durability by forming the layer of a magnetic developer contg. a specified composite or its deriv. in a thickness smaller than the gap of a developing zone on a developer carrying cylinder, and transferring the developer in said zone to an electrostatic image bearing drum to develop it. CONSTITUTION:An electrostatic image bearing drum 1 for holding it on the surface and a developer carrying cylinder 2 for holding an insulating magnetic developer on the surface are arranged at a predetermined gap in a developing zone. Said developer contg. a composite of phthalocyanine or its deriv. A and an N-contg. heterocyclic compd. or its deriv. B, or the deriv. of said composite is held on said cylinder 2 in a layer thinner than said gap. The developer is transferred in said zone to the drum to develop an electrostatic latent image. The one-component type insulating magnetic developer 6 fed from a developer hopper 4 is spread on the nonmagnetic cylinder 2 and the toner particles are triboelectrified with the cylinder 2 to an electrostatic charge reverse in polarity to the latent image. A doctor blade 5 made of steel is set near the cylinder 2 surface opposite to one of the magnetic poles of a multipolar permanent magnet 3, thus regulating the layer of the toner to small and uniform thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing method using an insulating magnetic developer.

Conventionally, developing methods for electrophotography, electrostatic recording, etc. are broadly classified into dry developing methods and wet developing methods. The former is
The method is further divided into two types: a method using a two-component developer and a method using a -component developer. Two-component developing methods include a magnetic brush method using an iron powder carrier, a cascade method using a bead carrier, a fur brush method using fur, etc., depending on the type of carrier for conveying the toner.

In addition, methods belonging to the -component type development method include the powder cloud method, in which toner particles are sprayed, and the contact development method, in which toner particles are brought into direct contact with the electrostatic latent image surface for development. , or toner development), a jumping development method in which the toner particles are not brought into direct contact with the electrostatic latent image surface, but are charged and flown toward the latent image surface by the electric field of the electrostatic latent image, and magnetic There is a magneto-dry method in which a conductive toner is brought into contact with an electrostatic latent image surface for development.

Two-component development methods inevitably use a developer mixture of carrier particles and toner particles, and as the development process normally consumes a much larger amount of toner particles than carrier particles, the mixing ratio of the two changes. However, it inherently has drawbacks such as fluctuations in the density of the visualized image and deterioration of image quality due to deterioration of carrier particles that are difficult to consume due to long-term use.

On the other hand, in the -component type development method, magnetic toner is used.
In the Magne Dry method and the contact development method that does not use magnetic toner, the toner comes into contact with the entire surface of the developing surface, that is, the image area and the non-image area, and this causes the toner to adhere even to the non-image area. There was a problem in that it was easy to cause dirt and stains due to so-called soil retention. (This fog staining problem also occurs in the two-component developing method.

) Furthermore, even in the powder-in-loud method, it is inevitable that toner particles in a powder state adhere to non-image areas, and it also has the disadvantage that it is impossible to remove ground blur.

In this regard, JP-A-54-43027, JP-A-55-
18656, etc., in which an electrostatic image holder that holds an electrostatic image on its surface and a developer carrier that carries an insulating developer on its surface are arranged with a certain gap in a developing section. The method of developing by carrying a developer on a developer carrier to a thickness thinner than the gap and transferring the developer to the electrostatic image holder in a developing section has the advantage that the above-mentioned fog does not occur easily. have. Furthermore, since carrier particles are not used, there is no variation in the mixing ratio as described above, and there is no deterioration of the carrier particles, making it an electrostatic image developing method with high fidelity and stable image quality.

In the conventionally known jumping development method, if copying is continued repeatedly, the uniformity of the developer layer carried on the developer carrier may be impaired in some cases, resulting in poor coating on the surface of streaks in the direction of movement of the carrier. This may cause the thickness of the supported developer layer to become extremely thick in some areas compared to the initial state, resulting in spot-like unevenness or uneven coating. The former may be observed as white streaks on the image when developed, and the latter may be observed as uneven density in the form of dots or serpentine waves. Although this phenomenon rarely occurs during normal repeated copying, it may occur especially during continuous use over long periods of time under extremely low temperature and low humidity environmental conditions, which is undesirable.

Further, even under high temperature and high humidity conditions, the thickness of the developer layer often changes and becomes thinner, which often causes an undesirable decrease in image density. As a result of repeated studies on this point, we found that one of the reasons for this is the stability and reliability of the charge control component, and these causes cause the developer powder to stick to the sleeve and transfer the developer powder from the sleeve. It was found that this is due to the change in

To be more specific, this phenomenon is caused by changes in environmental conditions in the developer layer supported on the carrier.
This is due to uneven portions of the amount of triboelectric charge. In other words, under ultra-low temperature and low humidity environmental conditions, friction between the surface of the carrier and the developer generates an extremely large component of triboelectric charge, and due to the mirroring force caused by this charge, the area near the carrier Such an extremely large component of triboelectric charge accumulates, and due to continuous durability, etc., this affects the uniformity of the developer coating in the upper layer of the developer layer and the ease of development. , the above-mentioned sun streaks, patch-like unevenness, and wavy coating defects occur. Further, the decrease in the thickness of the developer layer at high temperatures also occurs due to uneven triboelectric charging between the developer and the carrier, and is due to instability in the amount of triboelectricity of the developer near the surface of the carrier.

Static charge control agents used in dry developing toner include:
Examples include generally quaternary ammonium compounds and organic dyes, especially basic dyes and their salts. Common positive charge control agents include benzylmethyl-hexadecyl ammonium chloride, decyl-trimethylammonium chloride,
These include nigrosine base, nigrosine, safranin γ, and crystal/heolette. In particular, nigrosine base and nigrosine are often used as positive charge control agents. These are usually added to thermoplastic resins, thermally melted and dispersed, and then finely pulverized and adjusted to a suitable particle size as necessary before use.

However, these dyes used as charge control agents have complex structures, inconsistent properties, and poor stability. In addition, it is easily decomposed or deteriorated due to decomposition during thermal kneading, mechanical impact, friction, changes in temperature and humidity conditions, etc., and tends to cause a phenomenon in which charge controllability is deteriorated.

Therefore, when a toner containing these dyes as a charge control agent is developed using a copying machine, as the number of copies increases, the charge control agent decomposes or changes in quality, which may cause deterioration of the toner during durability.

Furthermore, most of the substances generally known to be positively chargeable have a dark color and therefore cannot be incorporated into a brightly colored developer.

Furthermore, since it is extremely difficult to uniformly disperse these positive charge control agents in a thermoplastic resin, they have the fatal drawback of causing a difference in the amount of frictional charge between toner particles obtained by pulverization. are doing. For this reason, various methods have been used to achieve more uniform dispersion. For example, basic nigrosine dyes are used by forming salts with higher fatty acids in order to improve their compatibility with thermoplastic resins, but often unreacted fatty acids or salt dispersion products are
It is exposed on the toner surface and contaminates the carrier or toner carrier, causing a decrease in the fluidity of the toner, fogging, and a decrease in image density. Alternatively, in order to improve the dispersion of these charge control agents into the resin, a method has also been adopted in which charge control agent powder and resin powder are mechanically pulverized and mixed in advance and then hot melt-kneaded. but,
The inherent poor dispersion cannot be avoided, and the current situation is that sufficient charge uniformity has not yet been obtained for practical use.

In addition, many positive charge control agents are hydrophilic, and due to poor dispersion in these resins, when pulverized after melting and mixing,
The dye is exposed on the toner surface.

Therefore, when the toner is used under high-temperature conditions, it has the disadvantage that a good quality image cannot be obtained because these charge control agents are hydrophilic.

In this way, when a conventional positive charge control agent is used in a toner, it can be applied to the toner particle surface between toner particles, between a toner and a carrier, or between a toner and a toner carrier such as a sleeve. This causes variations in the amount of charge generated,
Problems such as development fog, toner scattering, and carrier contamination are likely to occur. Furthermore, this problem becomes more noticeable when a large number of copies are made, and the result is that the copying machine is not suitable.

Furthermore, under high temperature conditions, the transfer efficiency of toner images decreases significantly, and many of them become unusable. Even at room temperature and humidity, when the toner is stored for a long period of time, it often deteriorates and becomes unusable due to the instability of the positive charge control agent used.

An object of the present invention is to provide a developing method with excellent durability such as continuous use characteristics.

Another object of the present invention is to provide a developing method that is stable against environmental changes such as high temperature and high humidity, and low temperature and low humidity.

Another object of the present invention is to provide a developing method that solves various problems associated with conventional chargeable toners, is uniformly and strongly charged, visualizes electrostatic charge images, and provides high-quality images.

The feature is that an electrostatic image carrier that holds an electrostatic image on its surface and a developer carrier that carries an insulating magnetic developer on its surface are arranged with a certain gap in the developing section. A
A magnetic developer containing a -B conjugate or a derivative thereof (A: phthalocyanine or a derivative thereof; B: a nitrogen-containing heterocycle or a derivative thereof) is supported on a developer carrier to a thickness thinner than the gap. The developing method comprises transferring the developer to the electrostatic image holder in a developing section to develop the image.

In particular, it is very effective to apply the above developing method to a developing device having a sleeve roller.

A-B conjugate (A; phthalocyanine or its derivative.

B; nitrogen-containing heterocycle or derivative thereof. ) is thermally and temporally stable, has low hygroscopicity, and has a type of functional separation between the coloring part and the charge control part, so it exhibits bright chromatic colors while reducing the amount of charge. It is a high quality positive charge control agent that can be controlled appropriately.

Of course, the above conjugate is also effective in its own form, but
In consideration of thermal stability, A is preferably copper phthalocyanine or a derivative thereof.

Furthermore, in consideration of charge controllability, it is preferable that B be a nitrogen-containing unsaturated heterocycle or a derivative thereof.

As is well known, the phthalocyanine derivatives used in the developer used in the present invention include halides such as chloro group, arylates such as phenyl group, mercapto group, thiocyan group, cyan group, amine group, etc.
It is possible to introduce hydrocarbon groups, halogenated hydrocarbon groups, nitro groups, sulfone groups, etc. singly or in combination.

Further, a form such as a so-called sulfur dye in which two molecules are bonded with a disulfide group is also possible. In addition, various metals can be used as metal complexes in addition to the commonly known copper complexes, including nickel, zinc, cobalt, aluminum,
Stable complexes with platinum, iron, vanadium, etc. are preferred.

Many nitrogen-containing heterocycles are known in the developer used in the present invention, and in addition to nitrogen, oxygen, phosphorus,
It is also possible to contain silicon, sulfur, etc. For example, etc. As well-known derivatives thereof, halides such as chloro group, arylates such as phenyl group, mercapto group, thiocyan group, cyan group, amine group, hydrocarbon group, halogenated hydrocarbon group, etc. It is possible to introduce a nitro group, a sulfone group, a glycidoxy group, a methacryl group, etc. singly or in combination.

Methods for incorporating the A-B combination into the developer include a method of adding it inside the toner particles and a method of adding it externally.

When internally added, the content of the control agent is preferably 0.5 to 50 parts by weight per 100 parts by weight of the resin.

In addition, when externally added, 0.0 parts by weight per 100 parts by weight of resin.
1 to 40 parts by weight is desirable.

As the binder resin of the toner, monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene; styrene-P-chlorostyrene copolymers, styrene-propylene copolymers, and styrene-
Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, Styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinylethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer,
Styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-? Styrenic copolymers such as Ray7 acid copolymer and styrene-maleate copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane 1. Polyamide, epoxy resin, polyvinyl butyral, 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 Can be used in combination.

Any suitable pigment or dye can be used as a colorant in the toner. For example, there are known dyes and pigments such as carphone black, iron black, phthalocyanine blue, ultramarine blue, quinacridone, and benzidine yellow.

It is also possible to add fluidity improvers such as silica and alumina.

To obtain a magnetic developer, a magnetic substance is contained in the toner. The magnetic substance used is a substance that becomes magnetized when placed in a magnetic field, and includes powders of ferromagnetic metals such as iron, cobalt, and nickel, and alloys and compounds such as magnetite, hematite, and ferrite. The content of this magnetic powder is preferably 15 to 70% by weight based on the weight of the toner.

The above toner composition is used as a microcapsule toner.
It can also be carried by wall materials, core materials, or both6.
It is Ding Noh.

A developing process to which the present invention is applied will be explained.

FIG. 1 shows a cross-sectional view of one embodiment of the developing process.

In the figure, the electrostatic image holder l moves in the direction of the arrow.

The non-magnetic cylinder 2, which is a developer carrier, rotates in the developing section so as to move in the same direction as the surface of the electrostatic image carrier. A multipolar permanent magnet 3 is arranged inside the nonmagnetic cylinder 2 so as not to rotate. The one-component insulating magnetic developer 6 sent from the developer container 4 is applied onto the non-magnetic cylindrical surface, and the friction between the cylindrical surface and the toner particles imparts a charge of opposite polarity to the electrostatic image charge to the toner particles. give. Furthermore, an iron doctor blade 5 is placed close to the cylindrical surface (at intervals of 50p to 500 colors),
By arranging the multipolar permanent magnet 3 so as to face one magnetic pole (the S pole in the figure), the thickness of one layer of the toner can be reduced to less than (3).
0p~300g) and uniformly. By adjusting the rotational speed of the cylinder 2, the surface speed and preferably the internal speed of the developer layer are made to be substantially equal to or close to the speed of the electrostatic image holding surface. Instead of iron, a permanent magnet may be used as the doctor blade 5 to form opposing magnetic poles. Further, an alternating current bias may be applied between the developer carrier and the electrostatic image holding surface in the developing section. This AC bias has f of 200 to 4000Hz,
It is sufficient if VPP is 500 to 3000V.

As described above, in this developing step, the non-magnetic cylinder 2 containing the multipolar permanent magnet 3 was used in order to stably hold the one-component magnetic developer on the developer carrier. In addition, in order to form a thin and uniform developer layer, a doctor blade 5 made of a magnetic thin plate or a permanent magnet was placed close to the surface of the cylinder 2. When a magnetic doctor blade is used in this way, opposing magnetic poles are formed between the magnetic poles of the permanent magnet contained in the developer carrier, and the toner particles are forced to stand up between the doctor blade and the developer carrier. This is advantageous in controlling the thickness of the developer layer in other parts of the developer carrier, for example, in the development part facing the electrostatic image surface. Further, by imparting such forced movement to the developer, the developer layer becomes more uniform, and a thin and uniform toner layer formation is achieved. Moreover, since the distance between the doctor blade and the sleeve can be set wide, it is also effective in preventing the destruction and aggregation of toner particles. When the toner particles are transferred in the developing area, they are transferred to the electrostatic image side due to the attraction action of the electrostatic image or the action of an alternating current bias.

The first characteristic of the developing method using the positively charged developer configured in this way is that the amount of triboelectric charge between toner particles or between toner and a toner carrier such as a sleeve is stable;
Moreover, the amount of charge can be controlled to suit the developing system used. Therefore, development fog and toner scattering around the edges of the latent image, which could not be solved satisfactorily in the past, are eliminated, high image density is obtained, and halftone reproducibility is improved.

Furthermore, even when the developer is used continuously for a long period of time, the initial characteristics are maintained, and high quality images can be used for a long period of time.

There are several additional properties that are of practical importance. One of these is that when used in environments with high temperatures and high humidity, the amount of triboelectric charge on the developer is stable and hardly changes with respect to room temperature and humidity, so there is no fogging or decrease in image density, and the latent image does not change. It is possible to perform faithful development, and furthermore, the transfer efficiency is excellent.

In addition, even when used under low temperature and low humidity conditions, the triboelectric charge distribution is almost the same as that under normal temperature and humidity conditions, and because there is no generation of developer components with extremely large charges, there is no decrease in image density or fog, and there is no roughness. It has the surprising property of almost no scattering during transfer.

The basic configuration and features of the present invention have been described above, and the method of the present invention will be specifically explained below based on Examples. However, this does not limit the embodiments of the present invention in any way. Parts in the examples are parts by weight.

[Example 1] 100 parts by weight of zinc oxide, 20 parts by weight of styrene-butadiene copolymer, 1.40 parts by weight of n-butyl methacrylate,
A mixture consisting of 120 parts by weight of toluene and 4 parts of 1% rose bengal 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 40K, and the solvent was evaporated with warm air to produce a zinc oxide binder-based photoreceptor in the form of a drum. This photoreceptor was subjected to a corona discharge of 16 KV to uniformly charge the entire surface, and then an original image was irradiated to form an electrostatic latent image.

The developer carrier has an outer diameter of 50 mm according to the configuration shown in Figure 1.
It is made of stainless steel cylindrical sleeve. The sleeve surface magnetic flux density was 700 Gauss, and the distance between the ear cutting blade and the sleeve surface was 0.2 mm. This sleeve rotation magnet fixation (sleeve peripheral speed is the same as that of the drum, rotation direction is opposite) type developing device was set at a distance between the photosensitive drum surface and the sleeve surface of 0.25 mm, and the sleeve rotation frequency was 400 Hzl 00
0Vc7) AC and -150V DC bias were applied.

Next, a sulfonyl chloride group was introduced into copper phthalocyanine using chlorosulfonic acid, and the mixture was reacted with aminophenylguanamine to obtain the following compound (1).

(1 in//') Using (1), a toner with an average particle size of 1 gm was prepared from the following ingredients.

Styrene-n-butyl methacrylate 100 parts Magnetite 60 parts Compound (1) 5 parts The toner was developed using the above-mentioned developing device, and then the powder image was transferred while irradiating a DC corona of 17 KV from the back side of the transfer paper. , a duplicate image was obtained. For fixing, use a commercially available plain paper copier (
Product name: NP-5000'.

Canonic acid).

The resulting transferred image had a reflection image density as high as 1.45, which was sufficiently high, had no fogging, and had no toner scattering around the image, resulting in a good image with high resolution.

Transfer images were continuously created using the IZ developer to examine durability, but the transferred images after 20,000 copies were also completely dull compared to the initial images.

In addition, when the H:j tomb conditions were set to 35°C and 85%, the image density was 1.38, a value that was almost unchanged from room temperature, and clear images were obtained without fogging or scattering, and the durability was also improved. There was almost no change up to 30,000 sheets. Next, when a transferred image was obtained at a low temperature and low humidity of 10° C. and 10%, the image density was as high as 1.82, solid black was developed and transferred extremely smoothly, and the image was excellent with no scattering or hollow spots. Durability tests were conducted under these environmental conditions, and copies were made both continuously and intermittently, and the density variation was ±0.2 up to 30,000 copies, which was sufficient for practical use.

[Example 2] Example 1 except that substance (2) was used instead of (1).
I did the same thing and got good results.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a developing process applicable to the present invention. 1----1 electrostatic image holder, 2----1 non-magnetic cylinder,
5--- Doctor blade, 6--- Insulating magnetic developer. Applicant Canon Co., Ltd.

Claims (1)

[Claims] An electrostatic image carrier that holds an electrostatic image on its surface and a developer carrier that carries an insulating magnetic developer on its surface are arranged with a certain gap in the developing section, and A-B combinations or their Derivative (However, A: Phthalocyanine or its derivative. B
: Nitrogen-containing heterocycle or its derivative. ) is supported on a developer carrier to a thickness thinner than the gap, and the developer is transferred to the electrostatic image carrier in a developing section for development. Method.