JPH0159577B2 - - Google Patents

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 an 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. 2297691
Although a number of methods are known, such as those described in the specification of No. 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 for removing residual toner on the photoreceptor is usually provided. Methods for visualizing electrical latent images using toner include, for example, the magnetic brush method described in U.S. Pat. No. 2,874,063, the cascade development method described in U.S. Pat. The powder cloud method described in U.S. Patent No.
A method using a conductive magnetic toner described in Japanese Patent Publication No. 3909258, 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. Positive charge control agents used in such dry developing toners include, for example, generally amino compounds, quaternary ammonium compounds, and organic dyes, particularly basic dyes and their salts. Ordinary positive charge control agents are
These include benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethylammonium 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, melted and dispersed, finely pulverized, and adjusted 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. In addition, decomposition or deterioration occurs due to decomposition during thermal kneading, mechanical impact, friction, changes in temperature and humidity conditions, etc., resulting in development with decreased charge controllability. Therefore, when a toner containing these dyes as a charge control agent is used for development in a copying machine, the dye decomposes or changes in quality as the number of copies increases, causing deterioration of the toner 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 dye is
In order to improve compatibility with thermoplastic resins, salts are formed with higher fatty acids, but unreacted fatty acids or salt dispersion products are often exposed on the toner surface, causing damage to the carrier or toner. Contaminates the carrier, resulting in decreased toner fluidity, fogging, and
This causes a decrease in image density.
Alternatively, in order to improve the dispersion of these dyes into the resin, dye powder and resin powder may be mixed in advance.
A method of mechanically pulverizing and mixing and then hot-melting kneading has been used, but the inherent poor dispersion cannot be avoided, and the reality is that sufficient uniformity of charge has not yet been achieved for practical use. It is. 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 they are crushed after melt-kneading. When using the toner under high humidity conditions,
Since these dyes are hydrophilic, they have the disadvantage that good quality images cannot be obtained. In this way, when a conventional dye with positive charge controllability is used in a toner, between the toner particles,
Alternatively, variations occur in the amount of charge generated on the surface of toner particles between the toner and the carrier, or between the toner and a toner carrier such as a sleeve, resulting in problems such as development fog, toner scattering, and carrier contamination. In addition, these problems appear as a particularly noticeable development when a large number of copies are made, resulting in a result that is practically unsuitable for copying machines. Furthermore, under high humidity conditions, the toner image transfer efficiency is significantly reduced, making it unusable. Furthermore, even at room temperature and humidity, when the toner is stored for a long period of time, 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 metal oxide powder treated with aminosilane is included as a component of the developer, but the inventors have investigated this method in detail, and found that
For example, colloidal silica, alumina, titanium dioxide, zinc oxide, iron oxide, γ-ferrite, magnesium oxide, etc. are treated with various aminosilane compounds, and a developer is prepared according to the examples described in the specification. It has become clear that in any combination, a developer exhibiting practically sufficient characteristics cannot be obtained and there are several drawbacks. That is, many developers fail to maintain desirable properties for consistently faithfully reproducing latent images. Even if a product exhibits desirable performance at the beginning, after long-term continuous use, it will no longer retain its initial characteristics and will become unusable. That is, fogging occurs, toner scatters around edges when copying line drawings, and image density also decreases. Other drawbacks include a decrease in image density, scattering of line drawings, white spots, and fog when developing and transferring under high temperature, high humidity, and low temperature and low humidity environmental conditions. This development is observed both in the development step and in the transfer step. 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, the present invention advantageously solves these drawbacks, and aims to improve the relationship between toner particles, between toner and carrier, and between toner and toner carrier such as a sleeve in the case of one-component development. The object of the present invention is to provide a developer that has a stable amount of triboelectric charge between the two and can be controlled to the amount of charge that is suitable for the developing system used. Still another object is to provide a developer for faithful development and transfer of the latent image, i.e., toner adhesion in the background area during development.
To provide a developer which is free from fogging and toner scattering around the edges of latent images, provides high image density, and has good halftone reproducibility. Still another object is to provide a developer that maintains its initial characteristics even when the developer is used continuously over a long period of time, and that causes no toner aggregation or change in charging characteristics. Another objective is to develop a developer that reproduces stable images unaffected 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. It's on offer. Still another object is to provide a developer with excellent storage stability that maintains its initial characteristics even during long-term storage. Specifically, the present invention provides a toner containing at least a binder resin and a magnetic powder or a colorant, and a silica fine powder produced by vapor phase oxidation of a silicon halogen compound, the silica fine powder having the following properties. General formula RmSiYn [wherein R is an alkoxy group or a chlorine atom, m is an integer of 1 to 3, Y is a nitrogen-containing unsaturated heterocycle or a derivative thereof (excluding derivatives having a quaternary amino group), The present invention relates to a positively chargeable developer containing a mixture of silica fine powder treated with a silane coupling agent (n is an integer of 3 to 1). 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, this method utilizes a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows. SiCl ₄ +2H ₂ +O ₂ →SiO ₂ +4HCl Also, in this manufacturing process, for example, by using other metal halogen compounds such as aluminum chloride or titanium chloride together with silicon halogen compounds, silica and other metal oxides can be combined. It is also possible to obtain composite fine powders, and these are also included. The particle size is preferably within the range of 0.001 to 2μ as an average primary particle size, particularly preferably 0.002 to 2μ.
It is best to use silica fine powder within the range of 0.2μ. As the silica fine powder produced by vapor phase oxidation of a silicon halogen compound used in the present invention, for example, there are those commercially available under the following trade names. AEROSIL (Japan Aerosil) 130 200 300 380 TT600 MOX80 MOX170 COK84 Cab-O-SiL (CABOTCo.) M-5 MS-7 MS-75 HS-5 EH-5 WackerHDK (WACKER-CHEMIE GMBH
N20 V15 N20E T30 T40 D-C Fine Silica (Dow Corning Co.) Fransol (Fransil Co.) Conventionally, examples of adding silica fine powder produced by vapor phase oxidation of silicon halogen compounds to developers are well 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 the inventors' research on the above development,
It has been found that fine silica powder produced by conventional vapor phase oxidation of silicon halogen compounds can reduce the charge or reverse the polarity of positively charged developers. Furthermore, a detailed study with the aim of obtaining a developer with a large and stable triboelectric charge amount revealed that the silica fine powder was produced by vapor phase oxidation of a silicon halide compound, and that the silica fine powder had the general formula RmSiYn. [Wherein, R is an alkoxy group or a chlorine atom, m is an integer of 1 to 3, Y is a nitrogen-containing unsaturated heterocycle or a derivative thereof (excluding derivatives having a quaternary amino group), and n is 3 It has been found that it is effective to include in a developer a fine silica powder treated with a silane coupling agent represented by the following formula. The silane coupling agent used in the present invention has the general formula R _n SiY _o [wherein R is an alkoxy group or a chlorine atom, m is an integer of 1 to 3, and Y is a nitrogen-containing unsaturated heterocycle or a derivative thereof ( (excluding derivatives having a quaternary amino group), n is an integer of 3 to 1], Y is a nitrogen-containing unsaturated heterocycle or a derivative thereof (excluding derivatives having a quaternary amino group), n is an integer from 3 to 1), and many nitrogen-containing unsaturated heterocycles have been known.
An example is given below.

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In addition, as derivatives, all known derivatives such as vinyl groups, mercapto groups, methacrylic groups, glycidoxy groups, ureido groups, etc. can be used as long as they do not interfere with the charge control properties of hydrocarbon groups, halo groups, amino groups, etc. and their derivatives can be used. The amount of the silane coupling agent treated with respect to the silica fine powder is 0.1 to 30 wt%, more preferably 0.5 to 30 wt%.
It is desirable that it be 20wt%. Furthermore, since the silica fine powder used in the present invention has a nitrogen-containing unsaturated heterocycle, it has an excellent effect on hydrophobization. It is also possible to treat with an organosilicon compound after treatment with a coupling agent or simultaneously with treatment with a silane coupling agent. Examples of such organosilicon compounds are hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, benzyldimethylchlorosilane. Silanes, bromutyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, chloromethyldimethylchlorosilane, triorganosilyl mercaptans, e.g. trimethylsilylmercaptan, triorganosilylacrylates, e.g. Vinyldimethylacetoxysilane, further dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 1 There are dimethylpolysiloxanes having from 2 to 12 siloxane units per molecule and containing one Si-bonded hydroxyl group in each of the terminal units. These may be used alone or in a mixture of two or more. The preferable weight ratio of the silane coupling agent compound and the hydrophobizing agent is 15:85 to 85:15, and by changing this ratio, the frictional electrification of the developer containing the silica fine powder can be improved. You can set the quantity value to the desired value and select this ratio for recognition. It also varies depending on the type of silane coupling agent and hydrophobizing agent used. The total amount of the silane coupling agent and the hydrophobizing agent is preferably 0.1 to 30 wt%, more preferably 0.5 to 30 wt%, based on the silica fine powder.
It is desirable that it be 20wt%. In addition, the applied amount of these treated silica fine powders exhibits an effect when the amount is 0.01 to 20% based on the weight of the developer, and it is particularly preferable that the applied amount is 0.1 to 3% to form a positive silica powder with excellent stability. It shows the charging property of . Regarding the preferred form of addition, it is preferable that 0.01 to 3% by weight of treated silica fine powder based on the weight of the developer be attached to the surface of the toner particles. The binder resin of the toner of the present invention includes monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene;
Styrene-P-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer , styrene
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dchlor Methyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer,
Styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-
Styrenic copolymers such as butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-isodene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, polymethyl methacrylate, Butyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyamide, polyacrylic resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic resin group hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin,
Parafine wax and the like can be used alone or in combination. Further, conventionally known positive charge control agents can also be used in combination with the treated silica fine powder used in the present invention. Various dyes include, for example, benzylmethyl-hexadecyl ammonium chloride, decyl-trimethyl ammonium chloride, nigrosine base, nigrosine hydrochloride, safranin gamma and crystal violet. Any suitable pigment or dye can be used as a colorant in the toner of the present invention. for example,
There are known dyes and pigments such as carbon black, iron black, phthalocyanine blue, ultramarine blue, quinacridone, and benzidine yellow. Furthermore, in order to use the toner of the present invention as a magnetic toner, it may contain magnetic powder. Such magnetic powder is a substance that is 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 15 to 70% of the toner weight.
Weight%. It is also possible to have the above toner structure carried on the wall material, the core material, or both of them in the microcapsule toner. Furthermore, the toner of the present invention is mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite powder, etc., as required, and used as a developer for electrical latent images. The developer of the present invention can be applied to various developing methods. For example, a magnetic brush development method, a cascade development method, a method using a conductive magnetic toner described in U.S. Pat. Examples include methods described in JP-A-54-42141, JP-A-55-18656, and JP-A-54-43027, a fur brush development method, a powder cloud method, an impression development method, and the like. In addition, when holding the developer in a developer carrier such as a sleeve, magnetic force, Coulomb force, electrostatic force,
It is possible to use image force, mechanical force, etc. The first part of the positively charged developer constructed in this way
When used as an electrophotographic developer, 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 one-component development is stable. In addition, since the amount of charge can be controlled to suit the developing system used, there is no development fog or toner scattering around the edges of the latent image, which could not be solved satisfactorily in the past, and high image density can be obtained, making it possible to improve halftone It has good 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. There are several additional 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 stable 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. In fact,
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 at room temperature and humidity.
Because there is no generation of developer components with extremely large charges, there is no reduction in image density or fog, and it has the surprising characteristics of almost no roughness or scattering during transfer. 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 selectivity with the binder resin used due to their poor dispersibility, and it is not possible 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 range of applicable toner compositions to be selected.
For example, in addition to heat fixing toners, it can be used in pressure fixing toner capsule toners. In particular, when the treated silica fine powder used in the present invention is attached to the toner particle surface, this effect is remarkable because the silica fine powder particles present on the toner surface mainly adjust the space charge on the toner surface. be. The basic structure and features of the present invention have been described above, and the developer of the present invention will be specifically explained below along with its method based on Examples. However, this does not in any way limit the embodiments of the present invention. Parts in the examples are parts by weight. Example 1 Styrene-n-butyl methacrylate 100 parts Copper phthalocyanine 10 parts Nigrosine 2 parts The above materials were thoroughly mixed in a blender and then heated to 150°C.
The mixture was kneaded using two heated rolls. After the kneaded material is left to cool naturally, it is roughly pulverized using a cutter mill, then pulverized using a pulverizer using a jet air flow, and further classified using an air classifier to obtain a fine powder (toner) with a particle size of 5 to 20μ. I got it. Next, silica fine powder Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd.) was placed in a closed Henschel mixer heated to 70°C, and diluted with alcohol so that the amount of silane coupling agent was 3.0% by weight based on the silica. N-(trimethoxysilylpropyl)imidazole was added dropwise while stirring at high speed. The obtained fine powder was dried at 120°C. The treated silica fine powder is 0.8% of the above fine powder.
A developer was obtained by adding 100 parts of an iron powder carrier having a particle size of 50 to 80 μm to 5 parts of the mixture by weight and mixing with a Henschel mixer. Next, a negative electrostatic image is formed on the OPC photoreceptor by a conventionally known electrophotographic method, and this is powder-developed using the above-mentioned developer using a magnetic brush method to create a toner image, which is then transferred to plain paper. It was fixed by heating. The resulting transferred image had a sufficiently high image reflection density of 1.30, 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 above developer to examine durability, but the transferred images after 20,000 sheets were also completely dull compared to the initial images. In addition, when the environmental conditions were set to 35℃ and 85%RH, the image density was 1.26, a value that was almost unchanged from normal temperature and humidity, and clear images were obtained without fogging or scattering, and the durability was 30,000 sheets. There was almost no change until then. Next, when a transferred image was obtained at a low temperature and low humidity of 10° C. and 10% RH, the image density was as high as 1.48, solid black was developed and transferred extremely smoothly, and the image was excellent with no scattering or hollow spots. Durability was tested under these environmental conditions, but the density variation was ±0.2 up to 30,000 sheets even though I copied continuously and intermittently.
This was sufficient for practical use. Comparative Example 1 A developer was obtained in the same manner as in Example 1, except that Aerosil 200 was not treated with the silane coupling agent, and development and transfer were carried out, but only an inverted image was obtained, and a negative charge was generated. showed his sexuality. Example 2 (Trimethoxysilyl)guanamine as a silane coupling agent, Example 1 was carried out in the same manner as in Example 1, except that .sub.1 was used, and almost the same favorable results were obtained. Example 3 Phthalocyanatodichlorosilane as silane coupling agent Example 1 was carried out in the same manner as in Example 1, except that .sub.1 was used, and almost the same favorable results were obtained. Example 4 The treated silica fine powder obtained in Example 1 was put into the Henschel mixer again, and while stirring, 2.0% by weight of dimethyldichlorosilane was added to the silica.
It was sprayed so that Stir at high speed for 2 hours at room temperature,
The mixture was further stirred at 80° C. for 24 hours, and then the mixer was opened to atmospheric pressure. The mixture was further dried at low speed at atmospheric pressure at 60°C for 5 hours. When the obtained treated silica fine powder was mixed with toner fine powder in the same manner as in Example 1, good results were obtained, and in particular, the reflected image density did not drop at all even under an environment of 35° C. and 85% RH.

Claims (1)

[Scope of Claims] 1. A toner containing at least a binder resin and magnetic powder or a colorant, and silica fine powder produced by vapor phase oxidation of a silicon halogen compound, wherein the silica fine powder has the following general formula: RmSiYn [wherein, R is an alkoxy group or a chlorine atom, m is an integer of 1 to 3, Y is a nitrogen-containing unsaturated heterocycle or a derivative thereof (excluding derivatives having a quaternary amino group), and n is A positively chargeable developer comprising a mixture of silica fine powder treated with a silane coupling agent represented by an integer of 3 to 1.