JPS5934539A - Developing agent - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic developer having stable triboelectrified amt. and a sharp and uniform distribution thereof, and capable of controlling it to a charge suitable for a developing system to be used, and visualizing a negative electrostatic latent image to give a high-quality image, by incorporating specified fine silica powder in the developer. CONSTITUTION:The present developer unaffected by change of temp. and humidity, and capable of retaining the initial characteristics even during long- term storage is obtained by treating the fine silica powder produced by vapor phase oxidation of silicon halide compds. with a silane coupling agent represented by formula I (R is alkoxy or C; m is 1-3; Y is a hydrocarbon group contg. at least one of amino, vinyl, glycidoxy, mercapto, methacrylic, or ureido; and n is 3-1), and further subjecting said silica to a treatment for enhancing hydrophobicness, so that it exhibits 30-80 hydrophobic value measured by the methanol titration test, and adding it to a toner.

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 electrostatically charged, visualizes a negative electrostatic charge image, and provides a high-quality image in a direct or indirect electrophotographic development method.

As a conventional electrophotographic method, U.S. Patent No. 2,2!37,89
Although a number of methods are known, such as those described in Specification 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. (hereinafter referred to as toner), and if necessary, the toner image is transferred to a transfer material such as paper, and then fixed by heat, pressure, solvent vapor, etc. to obtain a copy. In addition, if there is a process of transferring a toner image, it is usually a photoreceptor.
Two steps are provided to remove residual toner.

Development methods for visualizing electrical latent images using toner include, for example, the magnetic brush method described in U.S. Pat. No. 2,874,063 and the U.S. Pat. No. 2,818,552. Cascade development method and 2,221.7
Powder cloud method described in US Pat. No. 76, U.S. Pat.
, 908,258, a method using various insulating magnetic toners described in Japanese Patent Publication No. 41-8475, 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 JL 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 combined with carrier particles such as glass beads or iron powder.

Positive charge control agents used in such dry developing toners are, for example, generally amine compounds, quaternary ammonium compounds, and organic dyes, particularly basic dyes and their salts.

Common positive charge control agents include benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethylammonium chloride, nigrosine base, nigrosine hydrochloride, safranin gamma 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. In addition, decomposition or deterioration occurs due to decomposition during thermal kneading, mechanical impact, friction, changes in temperature and humidity conditions, etc., resulting in a phenomenon in which charge controllability decreases.

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 1 into the resin. For example, basic nigrosine dyes are used to improve compatibility with thermoplastic resins.
It is used by forming salts with higher fatty acids, but unreacted fatty acids or salt dispersion products are often exposed on the toner surface and contaminate the carrier or i-ner carrier, reducing the fluidity of the toner. This causes fog, a decrease in image density, and a decrease in image density. Alternatively, in order to improve the dispersion of these dyes into the resin, a method of mechanically pulverizing and mixing the dye powder and resin powder in advance and then hot-melting and kneading is also used, but this method is not as effective as the original method. The reality is that poor dispersion cannot be avoided, and that sufficient uniformity of charge has not yet been obtained for practical use.

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 these toners are used under high temperature conditions, they have the disadvantage that good quality images cannot be obtained because the dyes are hydrophilic.

In this way, when conventional dyes with positive charge controllability are used in toner, toner particles may form between toner particles, between toner and carrier, or between toner and toner carriers such as sleeves. This causes variations in the amount of charge generated on the particle surface, causing problems such as development fog, toner scattering, and carrier contamination. Furthermore, these phenomena become noticeable when a large number of copies are made, resulting in results that are not suitable for actual copying machines.

Furthermore, under high humidity conditions, the transfer efficiency of the 1.S image decreases significantly, 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 a metal oxide powder treated with aminosilane is contained as a component of the developer, but the inventor has studied this method in detail, and found that it is possible to use various aminosilane compounds, such as colloidal silica. , alumina, titanium dioxide, zinc oxide.

When iron oxide, γ-ferrite, magnesium oxide, etc. are processed to obtain a developer according to the examples described in the specification, in any combination, a developer exhibiting practically sufficient characteristics is obtained. It has become clear that there are some shortcomings.

That is, many developers fail to maintain desirable properties for faithfully reproducing an image. Even if a product exhibits desirable performance at the beginning, after continuous use over a long period of time, the product does not retain its initial characteristics and becomes unusable. 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.

There are various possible causes for these defects, but after investigating the above-mentioned phenomena, the inventors discovered that the main cause was a problem in the triboelectric charge distribution of the obtained developer. This point will be discussed later with specific examples.

That is, an object of the present invention is to stabilize the 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, and to maintain a stable triboelectricity distribution. To provide a developer that is sharp and uniform, and whose charge amount can be controlled to suit the developing system used.

Another objective is to develop the developer faithfully to the latent image and to use a developer for transfer, that is, to prevent toner smearing in the background area during development, 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 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 purpose of S et al. is to develop a developer that reproduces stable images unaffected by changes in temperature and humidity, especially a developer with high transfer efficiency that does not cause splatters or transfer omissions during transfer at high or low humidity. The purpose is to provide drugs.

Still another object is to provide a developer with excellent storage stability that maintains its initial characteristics even during long-term storage.

The present inventors have solved the various problems associated with conventional positively charged toners, as described in 2. As a result of intensive research aimed at providing an electrophotographic developer that gives group or chlorine atom; m is an integer of 1 to 3; Y is a hydrocarbon group containing at least one of an amino group, a vinyl group, a glycidoxy group, a mercapto group, a methacrylic group, and a ureido group; n is an integer of 3 to l ) A developer contains fine silica powder that has been treated with a silane coupling agent shown in the following formula and has been hydrophobized so that the degree of hydrophobization as measured by a methanol titration test is in the range of 30 to 80. It has been found that an electrophotographic developer exhibiting various excellent properties can be obtained by using the above method.

The silica fine powder produced by vapor phase oxidation of silicon halides referred to herein is so-called dry process silica or fumed silica, and is produced by conventionally known techniques. For example, this method utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas during oxyhydrogen heating, and the basic reaction formula is as follows.

Si CfLq + 2H2+o2→5i02 +4H
In addition, in this manufacturing process, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halide compounds such as aluminum chloride or titanium chloride together with a silicon halide compound. Also includes.

The average primary particle size of the particles is desirably within the range of 0.001 to 2, particularly preferably 0.0
02~0.211. It is better to use silica fine powder within the range of .

Commercially available silica fine powder produced by vapor phase oxidation of a silicon halogen compound used in the present invention includes, for example, those commercially available under the following trade names.

00 80 T600 OX80 MOX l 70 0K84 5-75 S-5 H-5 1 30 40 D -CFine 5ilica (Dow Corning, Inc.) Fransol (Fransi 1, Inc.) Conventionally, developer is produced by vapor phase oxidation of silicon halogen compounds. Examples of adding silica fine powder are known.

However, even if a developer contains a dye that can control positive charge, the chargeability changes to negative when such silica is added, making it unsuitable for visualizing negative electrostatic charge images. there were.

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 a positively charged developer or reverses its polarity.

Furthermore, a detailed study was carried out with the aim of obtaining a positively charged developer with a stable and high triboelectric charge amount and a sharp and uniform triboelectric charge distribution. (R is an alkoxy group or a chlorine atom; m is an integer of 1 to 3; Y contains at least one of an amino group, a vinyl group, a glycidoxy group, a mercapto group, a methacrylic group, and a ureido group) hydrocarbon group; n is an integer of 3 to 1), and hydrophobization treatment is performed so that the degree of hydrophobicity measured by a methanol titration test shows a value in the range of 30 to 80. However, it has been found that it is effective to incorporate the treated silica fine powder into a toner containing S.

Moreover, by changing the ratio of the steam silane coupling agent to the hydrophobizing agent and the total amount of treatment to select the degree of hydrophobization, when the treated silica fine powder is included in the toner, the amount of charge of the toner increases. We found that we can control the distribution completely freely.

− of However.

11
Mochi
狗■7 S Takataka Le-Ip ヰVノ■ ("S 碕 王JvJ l+-諌Ga 乍SIS■ :!lI C 方面 8. 幀 1 Saku tj''AJ 烰取IJ 8 はえ
Δ paper to nR. Convex.

Work ° to groan ya ′! In addition, the degree of hydrophobicity required for the silica fine powder used in the present invention, that is, the degree of hydrophobicity measured by a methanol titration test, is in the range of 30 to 80. A conventionally known hydrophobization method is used to impart hydrophobization to the silica by chemically treating it with an organosilicon compound that reacts with or physically adsorbs the silica fine powder. A preferred method is to treat fine silica powder produced by vapor phase oxidation of a silicon halide compound with an organosilicon compound after or simultaneously with the silane coupling agent.

Examples of such organosilicon compounds are hexamethyldisilazane, trictylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane,
Allyl phenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate 1, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyljethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, ■,3-diphenyltetramethyldisiloxane, siloxane, and 2 to 12 siloxane units per molecule with 1 siloxane unit each at the terminal position.
There are dimethylpolysiloxanes containing hydroxyl groups bonded to specific Si. These may be used alone or in a mixture of two or more.

The fine silica powder used in the present invention has been treated with the image processing agent, which is the silane coupling agent and hydrophobizing agent described above, so that when it is contained in a developer, the amount of triboelectric charge of the developer is stable. The preferred weight ratio of the silane coupling agent and hydrophobizing agent used to treat the silica fine powder is 15:85. ~85:15, and by changing this ratio, the triboelectric charge value of the developer containing the silica fine powder can be set to a desired value, and this ratio can be arbitrarily selected. It also varies depending on the type of aminosilane compound 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 20 wt%, based on the silica fine powder.

Finally, the degree of hydrophobicity of the treated silica fine powder was determined to be 30 as measured by methanol titration test.
When the developer is hydrophobized so as to exhibit a value in the range of 80 to 80, the amount of triboelectric charge of the developer containing such fine silica powder becomes sharp and exhibits positive chargeability that is not uniform, which is preferable.

Here, the methanol titration test is an experimental test to confirm the degree of hydrophobization of fine silica powder having a hydrophobized surface.

The “methanol titration test” specified herein to evaluate the degree of hydrophobicity on the treated silica fine powder
is done as follows. 0.2 g of silica fine powder to be tested 50++ l of water in an Erlenmeyer flask with a total volume of 250 ml
Add to j. Methanol is titrated from the burette until all of the silica is wetted. At this time, the solution in the flask is constantly stirred using a magnetic cooler. The end point is observed when the entire amount of fine silica powder is suspended in the liquid, and the degree of hydrophobization is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached.

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

Here, the reason why the developer of the present invention enables development and transfer faithful to the latent image will be speculated.

First, the method proposed in Japanese Patent Publication No. 53-22447, in which metal oxide powder treated only with aminosilane is included as a component of the developer, has several drawbacks as described above.

There are various reasons for these shortcomings, but as a result of research into the above-mentioned decrease, the inventor found that the main cause was a problem in the triboelectric charge distribution of the obtained developer.

In other words, when a developer contains metal oxide powder such as silica fine powder treated only with an aminosilane compound, it is often not possible to maintain the characteristics desirable for faithfully reproducing a latent image; The triboelectric charge distribution of the agent is extremely broad, and its value also changes depending on the environmental conditions in which it is used, resulting in variations. It is also confirmed that there is a developer having negative chargeability.

The triboelectric charge amount distribution referred to here is the amount of charge that should be measured in a state similar to the developing system used. In this case, the charging of developer particles is mainly carried out in the steps of contact with the carrier particle surface and peeling off, but a method for measuring the triboelectric charge distribution in such a developer system is described, for example, by L, B, 5chein et al. (J, Appl.

Phys, 4B, NO, +2. P5140 (+975)
) method, or the method of R, W, 5tover et al. (In2
Proc, Ann, Conf, Photo, Sci.

Engy 5PSE PI36) and R, B, Lev
is et al. (4th International Conf.
, orIEIelectrophoto, Adv, Pr1n
It is measured using the method of tPSI (1981).

In a developer having such a broad triboelectric charge amount distribution, developer components having a small charge amount cause fogging and scattering at the edges of the latent image, and oppositely charged components have a similar adverse effect. In addition, a developer component with a large amount of charge has a large physical mirroring force on a toner carrier such as a carrier or a developing sleeve, making it difficult to develop, which is undesirable as it causes a decrease in image density and roughness. . In addition, the triboelectric charge distribution of a developer containing fine silica powder treated only with such an aminosilane compound is likely to change depending on the environmental conditions, and is particularly suitable for development under conditions of high temperature, high humidity, and low temperature and low humidity. distribution. That is, at high temperature and high humidity, developer components with a small charge amount increase, and fogging, a decrease in image density, scattering of latent images at the edges, and a decrease in transfer efficiency become more significant. An example of this is shown in FIG. 1(b). In each figure, the horizontal axis represents the amount of triboelectric charge, and the vertical axis represents the ratio of toner showing each amount of charge.

For example, the triboelectric charge distribution of a developer containing fine silica powder treated only with an aminosilane compound remains broad even when the type and amount of the aminosilane compound relative to the fine silica powder is changed; It is only possible to obtain a developer containing components ranging from a small amount of triboelectric charge to a very large amount of triboelectric charge on a toner carrier such as . In addition, there is also a slight amount of oppositely charged component having a large value. An example of the triboelectric charge distribution of a developer containing the silica fine powder is shown in FIG. 4(a). In conventionally known development methods, the forces associated with the developer particles include electrostatic attraction to the latent image, and in some cases, external electric forces and mirror forces and adhesion to toner carriers such as carriers and developer sleeves. This is a cohesive force, and the adhesion of the developer particles to the latent image is achieved by the difference in force between the two to each individual developer particle.

At low temperatures and low humidity, developer components with a large amount of charge increase, resulting in a noticeable decrease in image density, roughness, and fog, and an increase in scattering and voids during transfer. An example of the triboelectric charge distribution under low temperature and low humidity is shown in FIG. 1(C).

In addition, especially at low temperature and low humidity, this tendency becomes even more pronounced with continuous use of the developer, making it impossible to maintain the initial characteristics and make it impossible to use it.

On the other hand, an example of the triboelectric charge distribution of the developer of the present invention is shown in FIGS. 2(a) to 2(C). As can be seen from the figure, the distribution is extremely sharp. A developer containing fine silica powder that has been treated with such a silane coupling agent and has been hydrophobized so that the degree of hydrophobicity determined by a methanol titration test is in the range of 30 to 80. Although the detailed reason for such a uniform and sharp triboelectric charge distribution is not clear, it is probably due to the interaction between the coupling agent and the hydrophobizing agent, resulting in an equilibrium between excess charge leakage and charge accumulation. (probably because it is stabilized at the same value) There are fewer components that have a negative effect on development and transfer,
Its distribution and values do not change much under the conditions of high temperature, high humidity, and low temperature and low humidity.

As the binder resin of the toner of the present invention, polymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyl I-luene; 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 Coalescence, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-alpha chloromethacrylate 2 full copolymer, styrene-acryloni !・Ryl copolymer,
Styrene-vinyl methyl ether copolymer, styrene-
Vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic copolymer Styrenic copolymers such as acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate-1, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyamide , polyacrylic acid resin, rosin,
Modified rosin, terpene resin, phenol 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.8 can be used, and all of the conventionally known dyes as positive charge control agents are mixed with the treated silica fine powder used in the present invention. Can be used in combination. For example, various dyes such as benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethylammonium chloride, nigrosine base, nigrosine hydrochloride, safranin gamma and crystal violet.

Further, in order to 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 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. A method using JP-A-54-42121, JP-A-55-18858,
Examples include the method 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 configured in this way is that it is treated with a silane coupling agent as a charge control agent;
In addition, since it uses silica fine powder that has been hydrophobized so that the degree of hydrophobization is in the range of 30 to 80, when it is used as a developer for electrophotography, there are
Or, the amount of triboelectric charge between the toner and the gear, or between the toner and a toner carrier such as a sleeve in the case of -component development, is stable and the distribution of the amount of triboelectricity is sharp and uniform;
Since it is possible to control and roll the charge amount to suit the developing system being used, there is no development fog or toner scattering around the edges of the latent image, which could not be solved in the past.
High image density can be obtained, and half-tone reproducibility is good.

Furthermore, even when the developer is used continuously over a long period of time, it maintains its initial characteristics, making it possible to produce high-quality images over 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 distribution of the developer is sharp and hardly changes from that under normal temperature and humidity. The reason is that it is possible to perform various transfers, and furthermore, that it has excellent transfer efficiency.

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 reduction in image density or fog, and there is no roughness. It has the surprising property of almost no scattering during transfer.

1 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 toners and capsule toners.

In particular, when the treated silica fine powder used in the wood invention is stuck 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, so this effect is is remarkable.

The basic structure and features of the Miki 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 wooden invention in any way. Parts in the examples are parts by weight.

[Example 1] Styrene-butyl methacrylate 100 parts by weight Carbon black 2 Nigrosine
3 tt-1 = The 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 with a cutter mill, then pulverized with 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 20 jL. Obtained.

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 to give a treatment amount of 2.0% by weight of the silane coupling agent to the silica. The mixture was stirred at high speed while dropping the γ-aminopropyltriethoxysilane. The obtained fine powder was dried at 120° C., then put into the Henschel mixer again, and while stirring, dimethyldichlorosilane was sprayed to the silica at a concentration of 2.0% by weight. The mixture was stirred at high speed for 2 hours at room temperature, 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. The degree of hydrophobicity was 50.

- 100 parts of iron powder carrier having a particle size of 50 to 80 pL was added to 5 parts of the treated silica fine powder added at 0.6 it percent to the above fine powder and mixed in a Henschel mixer, and mixed to obtain a developer.

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 developer using a magnetic brush method to create a toner image, which is transferred to plain paper. The film was then 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 developer described in Section 1 and the durability was examined, but the transferred images after 30,000 sheets were also completely dull compared to the initial images.

In addition, when the environmental conditions were set to 35°C and 185%, the image density was 1.39, a value that was almost unchanged from room temperature. Clear images were obtained without fogging or scattering, and the durability was almost unchanged up to 30,000 sheets. There wasn't. then 10°
When a transferred image was obtained at a low temperature and low humidity of 0.010%, the image density was as high as 1.60, solid black was developed and transferred extremely smoothly, and the image was excellent with no hollow spots or scattering. Durability tests were carried out under these environmental conditions, and even though copies were made continuously and intermittently, there was still no variation in density up to 30,000 copies.
The value was 0.2, which was sufficient for practical use.

The measurement results of the triboelectric charge distribution of this developer are shown in Figure 2 (a).
) to (C), a sharp distribution was observed under the conditions of room temperature, room temperature, high temperature and high humidity, and low temperature and low humidity.

[Comparative Example 1] A developer was obtained, developed, and transferred in the same manner as in Example 1 except that Aerosil 200 was not treated with γ-aminopropyltriethoxysilane and dimethyldichlorosilane, but an inverted image was obtained. The amount of triboelectric charge was -3,
It showed a negative charge of 2gc/g.

[Comparative Example 2] A developer was obtained in the same manner as in Example 1, except that the treatment with dimethyldichlorosilane was not performed, and an image was obtained in the same manner. At room temperature and humidity, there was little fog, but the image density was low at 0.84, line drawings were scattered, and solid black was noticeably rough. I checked the durability, but 2
The density decreased to 0.46 when 000 sheets were printed. 35°085
%, the image density was as low as 0.50, and fogging, scattering, and roughness increased, making it unusable. The transfer efficiency was also as low as 63%.

When an image was obtained under the condition of 10° CIO%, the image density was as low as 0.70, and there was severe scattering, fogging, roughness, and transfer omissions were noticeable. Did you perform continuous image output?
After approximately 0.00 sheets, the density was 0.40, making it impossible to put it to practical use.

The measurement results of the triboelectric charge distribution of which developer are shown in (a) in Figure 1.
) to (c) are shown as solid lines, and as mentioned above, the distribution was broad in all environments, and it was recognized that many components that affected development and transfer were included.

[Examples 2 to 5] The amounts of γ-aminopropyltriethoxysilane and dimethyldichlorosilane treated with respect to Aerosil 200 were 0.5% by weight, 1.0% by weight, and 2% by weight, respectively.
．． 0 weight percent, 5.0 weight percent and 10.
0 weight percent, 5.0 weight percent) and 10.
Good results were obtained when the procedure was carried out in substantially the same manner as in Example 1, except that 0 weight percent and 10.0 weight percent were used.

[Example 6] 10 pieces of the silica fine powder produced in Example 1 were kneaded,
The silica fine powder produced in Example 1 was crushed and classified to obtain 5 to 20 fine powders, and the silica fine powder produced in Example 1 was added at a ratio of 0.
Good results were obtained when the procedure was carried out in substantially the same manner as in Example 1, except that 3% by weight was added and mixed.

[Example 7] γ-aminoprobiltrie] xysilane N.

Good results were obtained when the same procedure as in Example 1 was carried out except that N-dimethylaminophenyltriethoxysilane was used instead.

[Example 8] Good results were obtained in almost the same manner as in Example 1 except that γ-aminopropyltriethoxysilane was replaced with aminoethylaminomethylphenethyltrimethoxysilane.

[Example 9] Example 1 except that the materials described in 1 were used as toner by the method of Example 1.
I did the same thing and got good results.

Table 1 shows the evaluation of each example and comparative example.

40

[Brief explanation of drawings]

FIG. 1 is a graph showing the triboelectric charge amount distribution of the developer used in Comparative Example 2. FIG. 2 is a graph showing the triboelectric charge amount distribution of the developer used in Example 1. Applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] A fine silica powder produced by vapor phase oxidation of a silicon halide compound, wherein the fine silica powder has the general formula % (R is an alkoxy group or a chlorine atom; m is an integer from 1 to 3). ; Y is a hydrocarbon group containing at least one of an amino group, a vinyl group, a glycidoxy group, a mercapto group, a methacrylic group, and a ureido group; n is an integer of 3 to 1) treated with a silane coupling agent; A developer characterized in that it contains fine silica powder that has been hydrophobized so that the degree of hydrophobization as measured by a methanol titration test is in the range of 30 to 80.