JPS59123850A - Developer - Google Patents

Abstract

PURPOSE:To obtain a high quality image by treating fine silica powder produced by the vapor phase oxidation of silicon halide with a titanate coupling agent, adding the treated silica powder to a developer so as to enable the uniform and intense positive electrostatic charge of the developer, and making a negative electostatic charge image visible with the developer. CONSTITUTION:This developer contains a binding resin, a coloring agent, and fine silica powder produced by the vapor phase oxidation of silicon halide and treated with a titanate coupling agent. Isopropyltriisostearoyl titanate, isopropyltrioctanoyl titanate, isopropyldiisostearoylcumylphenyl titanate or the like is used as the titanate coupling agent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developer for developing electrostatically charged images in electrophotography, electrostatic recording, electrostatic printing, etc. More specifically, the present invention relates to an electrophotographic developer that is uniformly and strongly positively charged, visualizes a negative electrostatic charge image, and provides a high-quality image in a direct or indirect electrophotographic development method.

Conventionally, as an electrophotographic method, U.S. Patent No. 2.297,69
Although a number of methods are known, such as in the specification of No. 1, in general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the latent image is transferred to a developing powder ( 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. Further, when a step of transferring a toner image is included, a step of removing residual toner on the photoreceptor is usually provided.

Examples of methods for visualizing electrical latent images using toner include the magnetic brush method described in U.S. Pat. No. 2,874,063, and the cascade method described in U.S. Pat. No. 2,618,552. Development method and 2.221,776
The powder cloud method described in U.S. Patent No. 3,9
A method using a conductive magnetic toner described in Japanese Patent Publication No. 09,258, a method using various insulating magnetic toners described in Japanese Patent Publication No. 41-9475, etc. are known.

As toners applied to these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and pulverizing the particles to about 1 to 30 μm are used as toner. As the magnetic toner, one containing magnetic particles such as magnetite is used. In the case of a system using a so-called two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder.

As a positive charge control agent used in such a dry developing toner, for example, an amine compound is generally used.

Quaternary ammonium compounds and organic dyes, especially basic dyes and their salts. Common positive charge control agents include benzyldimethyl-hexadecyl ammonium chlorite, tesylutrimethylammonium chloride, nigrosine base, nigrosine hydrochloride, safranin γ and crystal violet. In particular, nigrosine base and nigrosine hydrochloride are often used as positive charge control agents. These are usually added to a thermoplastic resin, heated and melted and dispersed, and then finely ground to adjust the particle size to an appropriate particle size as necessary before use.

However, these dyes used as charge control agents have complex structures, inconsistent properties, and poor stability. It also causes decomposition and mechanical decomposition during hot kneading.

Therefore, when a toner containing these dyes as a charge control agent is used for development in a copying machine, as the number of copies increases,
The dye decomposes or changes in quality, causing toner deterioration during durability.

Furthermore, since it is extremely difficult to uniformly disperse these dyes as charge control agents in thermoplastic resins, this has the fatal drawback of causing a difference in the amount of triboelectric charge between toner particles obtained by pulverization. have. For this reason, various methods have been used to more uniformly disperse these dyes into resins. For example, basic nigrosine dyes are used by forming salts with higher fatty acids in order to improve their compatibility with thermoplastic resins, but unreacted fatty acids or salt dispersion products often remain on the toner surface. When exposed, it contaminates the carrier or toner carrier, causing a decrease in toner fluidity, capri, and image density. Alternatively, in order to improve the dispersion of these dyes into the resin, there is no method of mechanically pulverizing and mixing the dye powder and resin powder in advance and then thermally melting and mixing them.

In addition, many of the positive charge controllable dyes are hydrophilic, and due to poor dispersion in these resins, the dyes are exposed on the toner surface when the dyes are melted and mixed and then crushed. When the toner is used under high humidity conditions, it has the disadvantage that a good quality image cannot be obtained because the dye is hydrophilic. When using a dye with a specific property in the toner, it is possible to prevent variations in the amount of charge generated on the surface of the toner particles between the toner particles, between the toner and the carrier, or between the toner and the toner carrier such as a sleeve. This causes problems such as development capri, toner scattering, and carrier contamination. These grooves become a particularly noticeable phenomenon when a large number of copies are made, and the result is practically unsuitable for copying machines.

Furthermore, under high humidity conditions, the toner image transfer efficiency is significantly reduced, making it unusable.

Furthermore, when the toner is stored for a long period of time even at room temperature and humidity, the toner often aggregates and becomes unusable due to the instability of the positive charge control dye used. .

Furthermore, Japanese Patent Publication No. 53-22447 proposes a method for obtaining a developer with positive charge control properties.

This is a method in which a metal oxide powder treated with an amine treatment run is included as a constituent component of the developer. If you use it,
Colloidal silica, alumina, titanium dioxide, zinc oxide,
When a developer is obtained by treating iron oxide, γ-ferrite, magnesium oxide, etc. and following the examples described in the specification, any combination has sufficient properties for practical use. However, it was found that there were several drawbacks.

In other words, many developers fail to maintain desirable properties for faithfully reproducing latent images, and even those that initially exhibit desirable performance do not retain their initial properties after long-term continuous use and become unusable. It becomes unbearable and I give up. That is, fogging occurs,
When copying line drawings, toner scatters around the edges and the image density also decreases.

Other drawbacks include a decrease in image density when developing and transferring under high temperature, high humidity, and low temperature and low humidity environmental conditions.
Scattering of line drawings, white spots, fogging, etc. occur. This phenomenon is observed both in the development process and in the transfer process.

Another drawback is that the developer cannot be stored for long periods of time.

That is, if the developer remains unused for a long time, its initial characteristics deteriorate and the developer becomes unusable.

That is, an object of the present invention is to provide a stable and uniform amount of triboelectric charge between toner particles or between a toner and a carrier, or between a toner and a toner carrier such as a sleeve in the case of component development. The purpose of the present invention is to provide a developer that can control the amount of charge suitable for a developing system.

Another purpose is to develop and transfer a latent image faithfully using a developer, that is, toner adhesion in the ground area during development, to prevent fogging and toner scattering around the edges of the latent image. The object of the present invention is to provide a developer which can obtain high image density without any problems and has good reproducibility of no-ftones.

Still another object is to provide a developer which maintains its initial characteristics even when the developer is continuously used over a long period of time, and which does not cause toner aggregation or change in charging characteristics.

Another objective is to develop a developer that reproduces stable images that are not affected by changes in temperature and humidity, especially a developer that has high transfer efficiency and does not cause scattering or transfer dropouts during transfer at high or low humidity. On offer.

Still another object is to provide a developer with excellent storage stability that maintains its initial characteristics even during long-term storage under high temperature and high humidity conditions.

The inventors of the present invention have solved the various problems associated with the conventional positively charged toner as described above, and have created an electronic system that can be uniformly and strongly positively charged, visualize a negative electrostatic charge image, and produce high-quality images. As a result of intensive research with the aim of providing a photographic developer, we have found that fine silica powder produced by vapor phase oxidation of silicon halogen compounds can be treated with a titanate-based coupling agent and incorporated into a developer, resulting in a variety of excellent properties. It has been found that an electrophotographic developer can be obtained which exhibits the following properties.

The silica fine powder produced by vapor phase oxidation of a silicon halogen compound referred to herein is so-called dry process silica or fumed silica, and is produced by a conventionally known technique. For example, the basic reaction formula for a method that utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame is as follows.

5ict4+ 2L + Ot −+ 5iO7+ 4
HCJAlso, in this manufacturing process, for example, by using other metal compounds such as aluminum chloride or titanium chloride together with silicon compounds, it is also possible to obtain a composite fine powder of silica and other metal oxides. Possible and inclusive.

The particle size is desirably within the range of 0.001 to 2μ as an average primary particle size, particularly preferably 0.002μ.
It is preferable to use silica fine powder within the range of ~0.2μ.

Commercially available fine silica powder produced by vapor phase oxidation of silicon-based compounds used in the present invention includes, for example, those commercially available under the following trade names: 0 AERO8IL 130 (Nippon Aerosil Co., Ltd.) 20000 80 TT600 0X80 0X170 0K84 Cab-0-8iL M-5 (CABOTCO, MS-7S-75 I (S-5 H-5 WacKerHDK N20N20 (WAC)
KER-CHE GMBH) 15 20E 30 40 D-CFine 5ilica (Dow Corning CqTsuji) FranSOL (Fr'anSi1) Conventionally, an example of adding silica fine powder produced by vapor phase oxidation of a silicon halide compound to a developer is publicly known.

However, even in a developer containing a dye having positive charge control properties, when such silica is added, the chargeability changes to negative, making it unsuitable for visualizing a negative electrostatic charge image. As a result of research into the above-mentioned phenomenon, the present inventor found that fine silica powder produced by conventional vapor phase oxidation of silicon halogen compounds reduces the charge of positively charged developer;
Alternatively, we discovered that the polarity can be reversed. Furthermore, detailed studies aimed at obtaining a developer with a stable and high triboelectric charge amount and uniform positive chargeability revealed that a developer prepared by treating such fine silica powder with a titanate coupling agent was developed. It has been found that the amount of triboelectric charging of the developer can be stably controlled and is effective when it is contained therein. More specifically, it is particularly desirable to use the treated silica fine powder in a state in which it is attached to the surface of toner particles consisting of at least a binder resin and a colorant.

A proposal to use a titanate coupling agent in a toner is disclosed in Japanese Patent Application Laid-open No. 55-26519.

There are methods described in Publications No. 55-28019 and No. 56-51755, but these methods basically depend on the dispersibility of the magnetic material in the resin in the magnetic toner.

Although this proposal is aimed at improving affinity, and it is true that dispersibility is improved, in such a method, the titanate-based camping agent does not affect the charging characteristics of the developer in any way, and is inconsistent with the technical content and idea of the present invention. are different.

The titanate coupling agent used in the present invention is an organic titanium compound capable of reacting with or adsorbing the hydroxyl groups or adsorbed water on the surface of the fine silica powder to form a broken membrane on the surface of the fine silica powder. For example, there are the following.

yamuto mamu too ma)hemo− ``----] !
Yama-Ki Th ”v^ Mo! Nmo Mouth 1 Shot Mo Y^ Mo "-1111-1 ζ Har-1- Mo ℃) ℃ Mo too Mamut■ -L Mo
[N mo [N toya]
M also 1 to ki t ° ki
Somo °he se mosu m 田” ``;=-m-] 1) 匡) SEM °・Sa さも “・kih訃”-ko; jh `` H also mentioned above, as for the method of treating fine silica powder with a titanate coupling agent, the titanium coupling agent used in the present invention is capable of absorbing chemically or physically bound water present on the surface of fine silica powder. Because it easily chemically reacts with the coating and forms a coating, a wide range of treatment methods can be used, including both dry and wet methods. For example, fine silica powder and a suitable titanium-based coupling agent are put into a mixer such as a Henschel mixer or a ball mill, and dry mixed. Alternatively, various methods can be used, such as a method in which a titanium-based coupling agent is dissolved in a suitable solvent, silica fine powder is added and mixed, and the solvent is removed.

The amount of the titanate coupling agent to be treated with respect to the silica fine powder is 0.01 to 20% by weight (preferably 0.01 to 20% by weight).
．． 1 to 10% by weight). Further, in addition to the titanate coupling agent described above, it is also preferable to use a known silane coupling agent in combination.

In addition, the paper to which these treated silica fine powders are applied exhibits an effect when the amount of the developer is 0.01 to 20 inches, and especially when 0.1 to 3 inches is added, excellent results are obtained. Shows stable positive chargeability. Regarding the preferred form of addition, it is preferable that 0.01 to 3 weight of treated silica fine powder be attached to the surface of the toner particles based on the weight of the developer.

Examples of the binder resin of the toner of the present invention include monopolymers of styrene and substituted products thereof such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene; styrene-P-chlorostyrene copolymers, and styrene-globylene copolymers. , styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-
Butyl methacrylate copolymer, styrene-alpha chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer! ! styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-
Styrenic copolymers such as acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; 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. can be used alone or in combination.

As the coloring material used in the toner of the present invention, conventionally known carbon black, iron black, etc. can be used, and all conventionally known dyes as positive charge control agents can be used in combination with the treated silica fine powder used in the present invention. I can do that. For example, various dyes such as benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethylammonium chloride, nigrosine base, nigrosine hydrochloride, safranin gamma and crystal violet.

In order to still use the toner of the present invention as a magnetic toner,
It may also contain magnetic powder. As such magnetic powder, a substance that is magnetized when placed in a magnetic field is used, 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 15 to 70% by weight based on the weight of the toner.

Furthermore, the toner of the present invention may contain iron powder if necessary.

It is mixed with carrier particles such as glass beads, nickel powder, ferrite powder, etc. and used as a developer for electrical latent images.

The developer of the present invention can be applied to various development methods. For example, a magnetic push development method, a cascade development method, a method using conductive magnetic toner described in U.S. Pat. Method using toner, JP-A-5
Publication No. 4-42141, Publication No. 55-1.8656,
Examples include methods described in Japanese Patent Publication No. 54-43027, a fur brush development method, a powder cloud method, and an impression development method.

The first characteristic of the positively charged developer constructed in this way is that it uses fine silica powder treated with a titanate coupling agent as a charge control agent, so it is particularly useful as a developer for electrophotography. When used, the amount of triboelectric charge between toner particles, between toner and carrier, or between toner and toner carrier such as a sleeve in the case of component development is stable and uniform, and is suitable for the developing system used. Because the amount of charge can be controlled, there is no development fog or toner scattering around the edges of the latent image, which could not be solved satisfactorily in the past, resulting in high image density and good halftone reproducibility. .

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.

Additionally, there are some properties that are of practical importance.

One of these is that when used in high-temperature, high-humidity environments, the triboelectric charge of the developer is uniform and hardly changes from that at room temperature and humidity, which prevents fogging, decreases in image density, and allows development to be faithful to latent images. Furthermore, it has excellent transfer efficiency.

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

Another feature is its excellent storage stability, which maintains its initial properties even during long-term storage.

Another feature is that conventional pigments and dyes that control positive charge have poor dispersibility and are therefore selective with the binder resin used, making it impossible to combine them with any resin. However, there is no selectivity between the silica fine powder used in the present invention and the resin, and it can be combined with any resin, allowing a wide selection of applicable toner configurations. For example, in addition to heat fixing toner, it can be used for pressure fixing toner and capsule toner.

In particular, when the treated silica fine powder used in the present invention is attached to the surface of the toner particles, the silica fine powder particles present on the toner surface mainly adjust the space charge on the toner surface. The effect is remarkable.

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. The parts in the examples are parts by weight. Example 1 The above materials were thoroughly mixed in a blender and then kneaded with two rolls heated to 150°C. After the kneaded material was left to cool naturally, it was roughly pulverized using a cutter mill, then pulverized using a pulverizer using a jet stream, and further classified using an air classifier to obtain a fine powder with a particle size of 5 to 20μ. Ta.

Next, silica fine powder Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd.) was placed in a closed Henschel mixer heated to 70°C, and alcohol was added so that the amount of titanium coupling agent to the silica was 2.0% by weight. The diluted isopropyl triisostearoyl titanate was added dropwise while stirring at high speed. The obtained fine powder was dried at 120°C.

The treated silica fine powder was added in an amount of 0.6% by weight to the above fine powder, and 100 parts of iron powder carrier having a particle size of 50 to 80 μm was added to 5 parts of the soybean powder mixed in a Henschel mixer and mixed to obtain a developer. The amount of triboelectric charge was as high as +18.6μ.

? Next, by a conventionally known electrophotographic method,
A negative electrostatic charge image is formed, and this is powder-developed using the above-mentioned developer using the Buko magnetic brush method to create a toner image, which is then transferred to plain paper and heat-fixed. The resulting transferred image has a density of 1
．． 5, which was sufficiently high, and there was no fogging at all, and a good image with high resolution was obtained without toner scattering around the image.

Transfer images were continuously created using the above developer and durability was examined, but the transferred images after 100,000 sheets were also completely dull compared to the initial images.

In addition, when the environmental conditions were set to 35°C and 85%, the image density was 142, a value that was almost unchanged from normal temperature and humidity.
Clear images are obtained without fogging or scattering, and the durability is also 1.
There was almost no change up to 00,000 sheets. Then 10℃1
When a transferred image was obtained at a low temperature and low humidity of 0.05 C, the image density was as high as 1.40, solid black was developed and transferred extremely smoothly, and the image was excellent with no scattering or hollow spots. Durability was carried out under these environmental conditions, but it was continuous.

I also made copies, but the density fluctuation was ±0.2 up to 100,000 copies, which was sufficient for practical use.

Furthermore, an image was obtained after storing this developer in an environment of 35° C. and 90% for one month, and the image density was 1.38, which was almost the same as before storage, and the image quality was also good.0 [Comparative Example 1] A developer was obtained in the same manner as in Example 1, except that Aerosil 200 was not treated with Inglobil triisostearoyl titanate 1. Development and transfer were performed, but only an inverted image was obtained. The amount was -3.0μ, indicating negative chargeability.

[Example 2] The same procedure as in Example 1 was carried out except that isopropyl tri(N, N-dimethyl-ethylamino) titanate was used instead of isopropyl triisostearoyl titanate. The image density was as high as 1.31, and there was no fogging. An image faithful to the latent image with high resolution and no scattering or transfer omission was obtained.

Even in a durability test of 100,000 sheets, an image with no dark color was obtained compared to the initial image. This developer was heated at 35℃9.
An image was obtained after being stored for one month in an environment of 0, and the image density was 130, which was no different from before storage and the image quality was good.

In addition, when image printing was carried out in an environment of 35° C. and 85%, very good images were obtained from the beginning, and the images after 100,000 sheets were also good. The transfer efficiency was also excellent at 92 inches.

[Example 3] The same procedure as in Example 1 was carried out except that dianthranyl ethylene titanate was used in place of isopropyl triisostearoyl titanate in a manner that the silica was 10% heavier by weight, and the following was obtained. The developer exhibited excellent image quality and durability in various environments: low temperature and low humidity, high temperature and high humidity, and room temperature and normal humidity.

Claims (1)

[Claims] In a developer comprising at least a binder resin, a colorant, and a fine silica powder, the fine silica powder is a fine silica powder produced by vapor phase oxidation of a silicon halide compound, and the fine silica powder is a titanate-based fine powder. A developer characterized by being treated with a coupling agent.