JPS61277965A - Developer having positive electric chargeability - Google Patents

Abstract

PURPOSE:To make possible the suppression of aggregation and the long-term maintenance of an electrostatic charge characteristic by incorporating pulverous silicic acid powder treated with a silicone oil having a nitrogenous heterocycle into a title developer. CONSTITUTION:The pulverous silicic acid powder treated with the silicone oil having a nitrogenous heterocycle is incorporated into the developer having positive chargeability. The treatment with the silicone oil having the nitrogenous heterocycle is executed at such a rate of 0.2-70wt% of the entire weight of the treated pulverous silicic acid powder and 0.0001-10wt% in the developer. The particularly good result is obtd. when the relation of the equation is satisfied where the pts.wt. of the silicone oil to be used with 100pts.wt. pulverous silicic acid powder prior to the treatment with the silicone oil is (x), the specific surface area of the pulverous silicic acid powder to be used is bm<2>/g and the nitrogen atom equiv. of the silicon oil having the nitrogenous heterocycle is (a). The initial characteristics are thus maintained even if the developer is continuously used for a long period of time. The aggregation of the toner and the change of the electrostatic charge characteristic are thus suppressed.

Description

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

Conventionally, many electrophotographic methods have been known, such as those disclosed in U.S. Pat. No. 2,297,691, but in general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means. Then, the latent image is developed using developer powder (hereinafter referred to as dotoner), and the toner image is transferred to a transfer material such as paper as necessary, and then fixed by heat, pressure, solvent vapor, etc., and then copied. It's about getting things. Furthermore, when a step of transferring a toner image is included, a step of removing residual toner on the photoreceptor is usually provided.

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 magnetic brush method described in U.S. Pat. No. 2,618,552. Cascade development method and 2,221,7
Powder cloud method described in US Pat. No. 76, U.S. Pat.
．． A method using conductive magnetic toner described in Japanese Patent No. 909.258 is known.

Conventionally, toners used in these development methods are fine powders in which dyes and pigments are dispersed in natural or synthetic resins. Finely pulverized particles of about 1 to 30 IL 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.

Examples of positive charge control agents used in such dry developing toners include quaternary ammonium compounds and organic dyes, particularly basic dyes and their salts.Common positive charge control agents include benzyl dimethyl- These include hexadecyl ammonium chloride, decyl-trimethyl ammonium chloride, nigrosine base, nigrosine, safranin γ, and crystal violet.

In particular, nigrosine base and nigrosine are often used as positive charge control agents. These are usually added to a thermoplastic resin, heated and melted and dispersed, and then 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, poor stability, and are susceptible to decomposition during thermal kneading, mechanical shock, friction, changes in temperature and humidity conditions, etc. It is easily decomposed or altered, and tends to cause a phenomenon in which charge controllability is deteriorated.

Therefore, when a toner containing these charge control agents is used for development in 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.

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 humidity conditions, there is a problem in that good quality images cannot be obtained because these control agents are wood-philic.

In this way, when a conventional positive charge control agent is used in a toner, it can be used between toner particles or between toner particles.

Between the toner and the carrier, and between the toner and the toner carrier such as a sleeve, variations occur in the amount of charge generated on the surface of the toner particles, which tends to cause problems such as development fog, toner scattering, and carrier contamination. In many cases, the toner image transfer efficiency decreases significantly when the number of copies is large and the weight is high, and under high temperature conditions, and many are unusable.
Furthermore, 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.

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 after a detailed study of this method, various aminesilane compounds were used, such as colloidal silica, alumina, dioxide, etc. When titanium, zinc oxide, saponified iron, γ-ferrite, magnesium oxide, etc. are processed and a developer is obtained according to the examples described in the specification, any combination has sufficient properties for practical use. It became clear that there were several problems.

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. That is, fogging occurs,
When copying line drawings, toner scatters around the edges and the image density also decreases. Other problems include a decrease in image density, scattering of line drawings, white spots, and fog when developing and transferring under high temperature and high humidity environmental conditions.

Another method for obtaining a developer with positive charge control properties is the method described in Japanese Patent Laid-Open No. 59-201063. In this method, as a component of the developer, instead of the aforementioned fine metal powder treated with 7-minosilane, fine soap powder treated with silicone oil containing an amine in the side chain is included. By this method, the problems of the developer containing fine metal powder treated with 7-minosilane can be compensated for, and a developer can be obtained that exhibits sufficient characteristics for practical use. It has become clear that some problems may occur during development and transfer if the film is left unused for a long period of time.

In other words, if it is left unused for a long period of time under high temperature and high humidity, it tends to cause a decrease in image density, scattering of line drawings, white spots, fogging, etc. when developing and transferring several sheets that start copying again. There is.

An object of the present invention is to provide a developer having positive chargeability.

A further object of the present invention 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 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 failure 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 after long-term storage.

Still another object is to provide a colorless charge control agent for color toners that exhibits positive chargeability.

Still another object is to provide a developer that has excellent developability and high transfer efficiency even after being left unused for a long period of time under high temperature and high humidity conditions.

The feature of the present invention is that the positively charged developer contains fine silicic acid powder treated with nitrogen-containing, heterocyclic-containing silicone oil.

As the silicic acid fine powder constituting one of the constituent components of the developer in the present invention, silicic acid fine powder produced by a dry method or a wet method can be used.

The dry method mentioned here is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halide compound. The reaction formula is as follows.

Si cua+2H2+02+5i02+4Hci also,
In this manufacturing process, for example, aluminum chloride or
It is also possible to obtain a composite fine powder of silica and other metal oxides by using another metal halide compound such as titanium chloride together with a silicon halide compound, and these are also included.

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.

AERO3I L 130 (Japan Aerosil 200oxs.

T600 0X80 0X170 0K84 Ca-0-5i L
M-5 (CABOT Co,'lr:)
MS-7MS-5 H-5 Wacker HDK N 20
V15 (WACKER-CHEMIE GMBH
2f) N20ED-CFine 5ilica (Dow Corning Co., '/D Fransol (Fransill) On the other hand, as a method for producing the silicic acid fine powder used in the present invention by a wet method, various conventionally known methods can be applied.
For example, the decomposition of sodium silicate by acid can be expressed by the general reaction formula (the reaction formula is omitted below): Na20-XS i02+H(,!; L+H20+5i
02IInH20+NacuOther methods include decomposition of sodium silicate with ammonia salts or alkali salts, generation of alkaline earth metal silicates from sodium silicate and then decomposition with acid to produce silicic acid, method of converting sodium silicate solution to ion exchange resin There are methods of using natural silicic acid or silicates, etc.

As the silicic acid fine powder referred to herein, any of anhydrous silicon dioxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate can be used.

Commercially available fine silicic acid powders synthesized by a wet method include those sold under the following trade names, for example.

Carplex Shionogi & Co., Ltd. 21 Pu Seal Nippon Silica Toxeal, Fine Seal Toku Sansoda Vita Seal
Multi-wooden fertilizer Jiruton, Silnetkus
Mizusawa T-Starsil
Kamijima Kagaku Himezil Ehime Pharmaceutical Thyroid Fuji Davison ItSHi-5il (Hi-Seal)
PittsburghPlate Glass C
o.

(Pittsburgh Plate Glass) Durosil Fii
llstoff-GeseUltrasil 1lSchaft Marquar
H
ardman andolden HOeSCh Chem
ische Fabrik Hoesch K-
G (Hiemitsussie Fabrik Herash) Sil-5tone 5ton
er Rubber (Silstone) G
o, (Stoner Lover) Nalco
Na1co Chem, Co.

(Narco Chemical) Quso Ph1
ladelphiaQuartz Co.

(Philadelphia Quartz) Santo ce 11 (Santo cell) Mon
5anto Chemical Co.

(Monsanto Chemical) Imsil Illin
oisMinerals Co.

(Illinois Mineral) Calcium 5ilikat Chem
fsche (calcium silicate)
Fabrik Hoesch.

-G (Hiemitsushe Fabrikherash) Calsil (Calsi/I/) Fii
llstoff-Gesellschaft Marquart Fortafil Imper
ialChemical' Industries LLd.

(Imperial Chemical Industries) Microca+ (Microcal) Jos
ephCrosfield & 5ons, Ltd.

(Jiecef Crossfield and Sunriki Manosil Hardman
andHolden Vulkasi 1 Farb
enfabrikenBryer, A.-G.

(Fal (Faburi Kenbaya) Tufknit (Tough Knit) D ur
h am Chemical Ls, Ltd.

(Doulham Chemical Power Silmos Shiraishi Kogyo Starex Kamijima Kagaku Furikosil
Among the silicic acid fine powders mentioned above, the specific surface area due to nitrogen adsorption measured by the BET method is 3.
A value within the range of 0rrf/g or more (particularly 50 to 4oorn'/g) gives good results.

Conventionally, it is known that fine silica powder produced by vapor phase oxidation of a silicon halide compound is added to a developer. However, even in a developer containing a dye or the like that has positive charge control properties, when such silica is added, the chargeability changes to negative, making it difficult to visualize a negative electrostatic charge image or reverse develop a positive electrostatic charge image. It was unsuitable for visualization.

Conventionally, a method of processing with silicone oil having an amine in the side chain or a method of processing with an aminosilane coupling agent is known, but in order to obtain a developer that exhibits more stable and uniform positive chargeability, detailed studies have been conducted. As a result, it was found that it is effective to treat fine silicic acid powder with a silicone oil containing a nitrogen-containing heterocycle and incorporate it into a developer.

The silicone oil having a nitrogen-containing heterocycle used in the treatment of the silicic acid fine powder is preferably a silicone oil having a nitrogen-containing heterocycle in the side chain, for example, a silicone oil having a structure represented by formula (I). can be used.

R4R5-1--(1) [Here, R1 and R9 represent hydrogen, an alkyl group, an aryl group, or an alkoxy group, R2 represents an alkylene group or a phenylene group, and R3 represents a substituent having a nitrogen-containing heterocycle. In the expression, R4 and R5 represent a hydrogen alkyl group or an aryl group, however, R2 may be omitted, and the above alkyl group, aryl group, alkylene group, or phenylene group may contain an amine, Further, it may have a substituent such as halogen within a range that does not impair chargeability. m and n are numbers of 1 or more, and the number is a positive number including O. ] Nitrogen-containing heterocycles include unsaturated and saturated ones, and examples of nitrogen-containing unsaturated heterocycles include the following.

Moreover, the following can be mentioned as an example of a saturated heterocycle containing nitrogen.

However, the present invention is not limited to the above-mentioned examples of compounds, but compounds preferably have a 5-membered or 6-membered heterocycle, and unsaturated rings tend to have more stable chargeability. Examples of strong derivatives include vinyl groups, mercapto groups, methacrylic groups, glycidoxy groups, as long as they do not interfere with the charge control properties of hydrocarbon groups and amine groups.
All known groups such as ureido groups can be derived, and derivatives thereof can be used.

Further, the nitrogen atom equivalent of the silicone oil used in the present invention is preferably 25,000 or less, particularly preferably 5,000 or less. The nitrogen atom equivalent here refers to the molecular weight in terms of the equivalent per nitrogen atom (g/equiu). It is the value divided by the number of nitrogen atoms present per molecule. These are 1
It may be used as a species or as a mixture of two or more types.

The treatment of the silicic acid fine powder with a modified silicone oil having a nitrogen-containing heterocycle can be carried out, for example, as follows. If necessary, the inorganic fine powder is violently agitated while being heated, and then the above-mentioned modified silicone oil having a nitrogen-containing heterocycle or its solution is sprayed or vaporized, or the silicic acid fine powder is mixed in the form of a slurry. This can be easily treated by dropping a modified silicone oil having a nitrogen-containing heterocycle or a solution thereof while stirring the mixture. Furthermore, it is also preferable to perform a heat treatment at a temperature of approximately 50 to 400°C thereafter.

After melting and mixing the silicic acid fine powder treated with the above-mentioned modified silicone oil having a nitrogen-containing heterocycle with a resin as a binder and a colorant, which are other constituent components of the toner,
A desired toner can be obtained by pulverizing and classifying into 5 parts. Alternatively, the above-described silicone oil-treated inorganic fine powder having a nitrogen-containing heterocycle may be added by mixing together with a toner formed from a resin, a colorant, or the like.

The amount of silicone oil having a nitrogen-containing heterocycle treated in the present invention is 0.2 to 7 of the total amount of treated silicic acid fine powder.
0% by weight and 0.0001-10% by weight in the developer.Furthermore, the appropriate amount of silicone oil containing a nitrogen-containing heterocycle is the silicone oil before processing with the silicone oil. X parts by weight of this silicone oil for 100 parts by weight of acid fine powder
When the specific surface area of the silicic acid fine powder used is brrf/g and the nitrogen atom equivalent of the silicone oil having a nitrogen-containing heterocycle is a, particularly good results are obtained when the relationship of formula (1) is satisfied. .

In the above equation,
When x>10, the silicone oil that accommodates nitrogen-containing heterocycles is in large excess relative to the silicic acid fine powder, causing problems such as silicone oil having nitrogen-containing heterocycles oozing out from the silicic acid fine powder. there is a possibility. Also.

b.

On the other hand, silicone oil containing nitrogen-containing heterocycle at 25°C
The viscosity is preferably 5000 cps or less, especially 30
00 cps or less is preferable.

If the viscosity is 5,000 cps or more, the silicone oil containing nitrogen-containing heterocycles will not be sufficiently dispersed in the silicic acid fine powder, which is likely to cause defective images such as fog.

In addition, the applied amount of these treated silicic acid fine powders exhibits an effect when the amount is 0.01 to 20% relative to the developed weight, and it is particularly preferable to exhibit excellent effects when added in an amount of 0.03 to 3%. A preferred form of addition that exhibits stable positive chargeability is 0.01 to 5% based on the weight of the developer.
Preferably, a weight percent of the treated silicic acid fine powder is attached to the surface of the toner particles.

Furthermore, the silicic acid fine powder used in the present invention may be treated with a silane coupling agent or a treatment agent such as an organosilicon compound for the purpose of hydrophobization, if necessary, and the method may be a known method. It is treated with the above-mentioned processing agent that reacts with or physically adsorbs the silicic acid fine powder. As such a processing agent.

For example, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, diethylaminopropyltrimethoxysilane, aminophenyltrimethoxysilane,
Dimethylaminophenyltriethoxysilane, dimethylsilicone oil, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, benzyldimethylchlor Silane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, Dimethyldimethoxysilane, diphenyljethoxysilane, hexa, methyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane,
and dimethylpolysiloxane, which has 2 to 12 siloxane units per molecule and contains one Si-bonded hydroxyl group in each unit located at the end. These may be used alone or in a mixture of two or more.

When a developer containing fine silicic acid powder treated with silicone oil having a nitrogen-containing heterocycle according to the present invention is used, the triboelectric charging of the developer is stabilized, and uniform positive charging is achieved even under various environments. Increased tendency to show gender. Therefore, by using the developer according to the present invention, it is possible to obtain clear, high-density images without fogging, and there is no image deterioration even when used continuously for a long period of time. Examples of the binder resin for the toner that can be used in the present invention, which can provide clear images, include polystyrene and poly-p-chlorostyrene.

Monopolymers of styrene and its substituted products such as polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid methyl copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-butyl acrylate-butyl maleate hafester copolymer, styrene-octyl acrylate copolymer, styrene - Methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethacrylate 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-maleic acid copolymer Polymers, styrenic copolymers such as styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, 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. can be used alone or in combination.

Coloring agents used in the developer of the present invention include known facial cleansing agents such as carbon black, phthalocyanine blue,
Indan Stremburu, Peacock Blue, Permanent Red, Lakelet, Rhodamine Lake, Hansa Yellow, Permanent Yellow, Benzidine Yellow W
Can be used widely.

In order to use the developer of the present invention as a magnetic toner, it may contain magnetic powder. As such magnetic powder, a substance that is magnetized when placed in a magnetic field is used, such as iron, cobalt, nickel, etc. There are powders of ferromagnetic metals such as, alloys and compounds of magnetite, hematite, ferrite, etc.

The content of this magnetic powder is 15 to 70% by weight based on the weight of the toner.

The toner is optionally mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite powder, etc., and used as a developer for electrostatic latent images.

The developer of the present invention can be applied to various development methods, such as magnetic brush development method, cascade development method, method using conductive magnetic toner described in U.S. Pat. No. 3,909,258, A method using a high-resistance magnetic toner described in JP-A-53-31138, JP-A-53-31138;
Examples include methods described in Japanese Patent Nos. 4-42121, 55-18656, and 54-43027, fur brush development method, powder cloud method, touchdown development method, impression development method, and the like.

[Example 1] 100 parts by weight of styrene-butyl methacrylate-dimethylaminoethyl methacrylate (weight ratio 7:2.5:0.5) copolymer, 60 parts by weight of magnetite, and 3 parts by weight of polyethylene wax were mixed and mixed in a low mill. Melt and knead. After cooling, it is coarsely pulverized using a hammer mill, and then finely pulverized using a jet pulverizer. Next, it was classified using an air classifier to obtain a black fine powder with a particle size of about 5 to 20 g.

On the other hand, while stirring 100 parts by weight of silicic acid fine powder (trade name: Aerosil #130, specific surface area: approximately 130 g/g, manufactured by Aerosil), the temperature was raised to approximately 25%.
While maintaining the temperature at 0°C, 20 parts by weight of silicone oil having a nitrogen-containing heterocycle in the side chain (viscosity at 25°C: 100 cps, nitrogen atom equivalent: 850) was sprayed and treated for 10 minutes.

Incidentally, silicone oil contains the structure of the following formula 1) as a constituent unit.

CH3 10-3i- (CH2)3 ■ 100 parts by weight of the black fine powder was treated with the silicone oil having a nitrogen-containing heterocycle in the side chain.
．． A toner was prepared by adding 4 parts by weight. A reprint copying machine (product name: NP150Z) uses the adjusted toner as a developer.
, manufactured by Canon Inc.) to produce an image, a clear image without fogging was obtained, and the image reflection density was 1.35. Further, in order to examine the durability of the developer, a durability test of 50,000 sheets was carried out, and a clear image (image density 1.37) without fog was obtained, which was the same as the initial image. On the other hand, when images were produced in the same manner under a high temperature and high humidity environment (30° C., 90% RH), the image density was 1.20, and a good image without fogging etc. was obtained.

Furthermore, when the image was printed after being left unused for two weeks during the durability test under high temperature and high humidity conditions, a clear image (image density 1.15) without fogging was obtained as before. moreover,
Clear and fog-free images were obtained even under a low temperature and low humidity environment (10° C., 10%).

[Example 2] Using 100 parts by weight of styrene-butyl methacrylate-dimethylaminoethyl methacrylate (weight ratio 7:2.5:0.5) copolymer, 65 parts by weight of γ-iron oxide, and 4 parts by weight of polyethylene wax. A fine powder was produced in the same manner as in Example 1 except for the following.

In addition, a silicone oil (trade name: Aerosil 0X-50, specific surface area approximately 50 m'/g manufactured by Aerosil Co., Ltd.) synthesized by a dry method and having a nitrogen-containing heterocycle in its side chain was added to 100 parts by weight lf. Viscosity 60C at 25°C
Example 1 using 1 part by weight of Ps, nitrogen atom equivalent 400)
processed in the same way.

In addition, silicone oil contains the structure of the following formula (m) as a structural unit.

CH3 (1) 0-3i- To 100 parts by weight of the fine powder, 1 part by weight of the silicic acid fine powder treated with the silicone oil having a nitrogen-containing heterocycle in the side chain was added to prepare a toner. When this toner was used as a developer and evaluated in the same manner as in Example 1, a clear sepia-colored image without fogging was obtained, and there was no deterioration of the image even when left in high temperature and high humidity conditions in the same manner as in Example 1. Ta.

[Example 3] 80 parts by weight of styrene-butyl methacrylate-dimethylaminoethyl methacrylate (weight ratio 7:2° 5:0.5) copolymer, styrene-butazinine (weight ratio 85:1)
5) 20 parts by weight of copolymer, 6 parts by weight of phthalocyanine blue, and 4 parts by weight of low molecular weight polypropylene were added in substantially the same manner as in Example 1 to obtain blue fine powder having a particle size of approximately 5 to 201 L.

On the other hand, 100 parts by weight of silicic acid fine powder (trade name, Aerosil #200, specific surface area 200 m''/g manufactured by Aerosil Co., Ltd.) synthesized by a dry method was added to a silicone oil having a nitrogen-containing heterocycle in the side chain (at 25°C). It was treated in the same manner as in Example 1 using 100 parts by weight (viscosity: 3,300 cps, nitrogen atom equivalent: 4,000).

Incidentally, the silicone oil contains the structure of the above formula (II) as its constituent unit.

12 parts by weight of the above blue fine powder, 0.3 parts by weight of treated silicic acid fine powder, and carrier iron powder (trade name, EFV250/400
．． E1 (manufactured by Hon Tetsuko Co., Ltd.) was mixed with 88 parts by weight to prepare a developer. On the other hand, a negative electrostatic latent image is formed on the OPC photoreceptor, this is developed with the above developer, and the resulting powder image is transferred to plain paper. (composed of a fuser roll coated with silicone rubber and a pressure roll whose surface was coated with silicone rubber). Clear blue images without fogging were obtained, and good images were obtained even under high temperature and high humidity conditions.

[Example 4] 100 parts by weight of silicic acid fine powder with a specific surface area of about 90 rrf/g synthesized by a wet method and silicone oil having a nitrogen-containing heterocycle in the side chain (viscosity 150 cps, nitrogen atom equivalent 17)
The procedure was carried out in substantially the same manner as in Example 1 except that 10 parts by weight of 00) was used, and the same results as in Example 1 were obtained.

In addition, silicone oil contains the structure of the following formula (IV) as its structural unit.

H3 0-5i- [Example 5] 100 parts by weight of silicic acid fine powder synthesized by a dry method (trade name: Azosil #380, specific surface area: 380 tn"/g manufactured by Aerosil) and nitrogen-containing side chains. The same procedure as in Example 1 was carried out except that 40 parts by weight of a silicone oil having a heterocycle (viscosity: 700, nitrogen atom equivalent: 1,000) was used, and a clear image without fogging was obtained.

In addition, clear images were obtained under high temperature and high humidity conditions.

Incidentally, silicone oil contains the structure of the above formula (II) as its constituent unit.

[Example 6] Specific surface area synthesized by wet method is approximately 120 rtf/g
The procedure was carried out in the same manner as in Example 1, except that 100 parts by weight of silicic acid fine powder and 15 parts by weight of silicone oil having a nitrogen-containing heterocycle in the side chain (viscosity 1200 cps, nitrogen atom equivalent 3500) were used. However, clear images with no fog were obtained. Further, good images were obtained even under high temperature and high humidity conditions, and there was no substantial change even after standing.

Incidentally, silicone oil contains the structure of the above formula (II) as its constituent unit.

[Examples 7 to 12] The same procedure as in Example 1 was performed except that silicone oil containing the following structure as a structural unit was used, and the same good results as in Example 1 were obtained.

α precedent 7) α precedent 8) Q overturning 9) Saving precedent 10) α precedent 11)
α Precedent 12) [Example 13) A silicone oil having a nitrogen-containing heterocycle in the side chain with a viscosity of 65 cps and a nitrogen a atom equivalent of 2100098
The procedure was carried out in substantially the same manner as in Example 1 except that parts by weight were used, and a good image was obtained, although slightly inferior to that in Example 1. The image density after being left for 2 weeks was 0.95.

[Example 14] The same procedure as Example 1 was carried out, except that the silicone oil used in Example 1 and the silicone oil having an amine in the side chain (viscosity at 25°C, 70 cps, amine equivalent: 830) were mixed at a ratio of 1/1. When the same procedure was carried out, a good fog-free image was obtained.

[Comparative Example 1] The same procedure as in Example 1 was carried out using untreated silicic acid fine powder without using the silicic acid fine powder treated with silicone oil having an amine in the side chain, but only a poor image was obtained. The zero image density that was not obtained was 0.21.

[Comparative Example 2] It was carried out in the same manner as in Example 1, except that an aminosilane coupling agent was used instead of the silicone oil having a nitrogen-containing heterocycle in the side chain, but in an environment of normal temperature and humidity. In this case, an image with an image density of 1.29 was obtained, but in a high temperature and high humidity environment, the image density decreased significantly to 0.3.
The angle was only 41 degrees, and only a poor image could be obtained. When the image was left for another two weeks, the image density decreased to 0.27.

[Comparative Example 3] Almost the same as Example 1 except that silicone oil having an amine in the side chain (viscosity at 25°C, 65 cps, amino equivalent weight 21,000) was used instead of the silicone oil having a nitrogen-containing heterocycle in the side chain. When tested, it was 1.05 in a normal temperature and humidity environment, and 0.97 in a high temperature and humidity environment.
An image density of 0.85 was obtained, but after being left unused for two weeks, the image density decreased to 0.85, although there was no practical problem.

The image densities under each environment in the examples are shown in the table below.

Claims (1)

[Claims] A positively charged developer comprising fine silicic acid powder treated with silicone oil having a nitrogen-containing heterocycle.