JPH03103864A - Toner for developing positive chargeable electrostatic charge image - Google Patents

Abstract

PURPOSE:To prevent the degradation in image density by adding the fine powder of positive electrostatic chargeable silica to colored fine powder formed by using a styrene copolymer having a phosphonium salt in the side chain as a charge control agent. CONSTITUTION:The fine powder of the positive electrostatic chargeable is added to the fine powder particles consisting of the copolymer expressed by formula I, a coloring material and a binder resin. In the formula, R<1> to R<3> denote hydrogen, alkyl group, aryl group, aralkyl group; X denotes anion; ldenotes 1 to 8 integer; m/n is 20/80 to 1/99 and denotes a polymn. ratio. Namely, the fine powder of the positive triboelectrostatic chargeable silica is made to exist in the toner of the styrene copolymer having the phosphonium salt in the side chain. The contamination of a toner carrying member is, therefore, prevented and the uniformity of the density of the solid image is improved. The images which are hardly deteriorated in image quality by continuous copying and has the excellent uniformity in density are obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is for use in positively charging electrostatic image development for visualizing electrostatic latent images in image forming methods such as electrophotography and electrostatic recording. Regarding toner.

[Prior Art] Conventionally, as an electrophotographic method, U.S. Patent No. 2,297,69
1, Special Publication No. 42-23910, and Special Publication No. 43
Various methods are described in Japanese Patent No. 24748 and the like.

The developing methods applied to these electrophotographic methods include:
Broadly speaking, there are dry development methods and wet development methods. The former can be roughly divided into methods using a two-component developer and methods using a single-component developer.

As toners applied to these dry 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. Further, in the case of a system using a two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder.

Either toner must have a positive or negative charge depending on the polarity of the electrostatic latent image being developed.

In order to make the toner hold an electric charge, it is possible to use the triboelectricity of the resin that is a component of the toner, but this method has a low chargeability of the toner, so the images obtained by development are easily fogged and blurred. Become something. Therefore, in order to impart appropriate triboelectric chargeability to the toner, dyes and pigments that impart chargeability, as well as charge control agents are added to the toner.

Charge control agents known in the art today include nigrosine dyes, azine dyes, triphenylmethane dyes, quaternary ammonium salts, and polymers having quaternary ammonium salts in their side chains. .

[Problems to be Solved by the Invention] However, since those containing these charge control agents tend to contaminate the sleeve or carrier, the amount of triboelectric charge of toners using them decreases as the number of copies increases. ,
Causes a decrease in image density. Furthermore, some charge control agents have insufficient triboelectric charge and are easily affected by temperature and humidity, causing environmental fluctuations in image density. Also,
Certain charge control agents have poor storage stability, and their triboelectric charging ability decreases during long-term storage. Furthermore, since some charge control agents have poor dispersibility in resins, toners using these agents have uneven triboelectric charge between particles and are prone to capping.

Additionally, some charge control agents are colored and cannot be used in color toners.

At present, there is a strong demand for the development of a charge control agent that satisfies all of these requirements.

That is, an object of the present invention is to provide a positively chargeable toner for developing electrostatic images that eliminates such problems.

[Means and effects for solving the problem] The present invention is characterized by adding positively chargeable silica fine powder to colored fine powder using a styrene copolymer having a phosphonium salt in the side chain as a charge control agent. This is a toner for developing positively charged electrostatic images.

A styrene copolymer having a phosphonium salt in its side chain has high positive triboelectrification and is colorless, so it is suitable as a charge control agent for color toners. Moreover, as a result of studies conducted by the present inventors, it was found that the amount of triboelectric charging of a styrene copolymer having a phosphonium salt in its side chain changes depending on the type of counter ion. Furthermore, the styrene copolymer having a phosphonium salt in its side chain causes very little contamination of toner carriers such as carriers or sleeves. Therefore, it has been found that in order to improve the contamination of toner carriers caused by styrene copolymers having phosphonium salts in their side chains, the mere presence of positively triboelectrically charged silica fine powder on the toner surface has a sufficient effect. Furthermore, images obtained with a toner containing a styrene copolymer having a phosphonium salt in a side chain are often rough. This is particularly noticeable in the case of one-component magnetic toner, and it has been found that this is caused by disturbances in the coating state of the toner on the sleeve.

When the positively triboelectrically charged silica fine powder was present on the toner surface, the toner coating on the sleeve became uniform, and the resulting image became finer. Furthermore, the toner containing the styrene copolymer having a phosphonium salt in the side chain had a somewhat slow triboelectric charging speed, so that a high-density image could not be obtained from the beginning. However, this problem could also be solved by making positive triboelectrically charged silica fine powder exist on the toner surface.

In this way, the present inventors have discovered that positively chargeable silica fine powder is essential to take advantage of the excellent properties of a styrene copolymer with a phosphonium salt in its side chain as a positive charge control agent. They discovered this and completed the present invention.

The molecular weight of the styrene copolymer according to the present invention is not particularly limited as it varies depending on the type of monomer, synthesis method, etc., but a weight average molecular weight of 5,000 to 50,000 is preferable. If the weight average molecular weight is less than 5,000, the number of phosphonium salts contained in the polymer will be insufficient, and good positive triboelectric charging properties cannot be maintained. In addition, the hygroscopicity of the phosphonium salt appears, and environmental fluctuations in the amount of triboelectric charge become large. When the weight average molecular weight exceeds 50,000, it may be difficult to obtain fine particles, and the compatibility with the binder resin deteriorates.

The charge control agent according to the present invention is selected from various structures. Examples include the following:

II3 Furthermore, the inclusion of a styrene copolymer having a phosphonium salt in the side chain in a toner is disclosed in Japanese Patent Application Laid-Open No. 63-2439.
It is publicly known from the publication No. 64. However, these include the positive I1! of the present invention! The effect of triboelectric silica fine powder is not mentioned. There is also no description of the effect of counter ions. In the present invention, it is essential to use a special styrene copolymer with excellent characteristics as a charge control agent for toner in combination with positively chargeable silica fine powder, and only one of them has satisfactory performance. A toner for developing electrostatic images cannot be obtained.

In the present invention, methods for incorporating the styrene copolymer having a phosphonium salt in the side chain into the toner include a method of adding it inside the toner and a method of adding it externally. The amount of these derivatives used is determined by the toner manufacturing method, including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is not uniquely limited. However, preferably 0 parts by weight per 100 parts by weight of the binder resin.
．． It is used in an amount of 1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight. When added externally, it is preferably added in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the resin, and is particularly preferably fixed to the surface of the toner particles by a mechanical method. The special styrene copolymer of the present invention can also be used in combination with a conventionally known charge control agent.

In addition, as the silica fine powder constituting a component of the developer in the present invention, silica fine powder manufactured 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 halogen derivative. For example, this method utilizes a thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen and hydrogen, and the basic reaction formula is as follows.

SiCj) 4+2 82+ 02→St(h+4 NC
In addition, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halogen derivatives such as aluminum chloride and titanium chloride together with silicon halogen derivatives in this manufacturing process, and these are also included. do.

On the other hand, various conventionally known methods can be applied to produce the silica fine powder used in the present invention by a wet method.

For example, the decomposition of sodium silicate with an acid can be expressed by the general reaction formula (the reaction formula is omitted below): Na20.XSi02+HCj) +H20 -+Si
O2・nH20 +NaCfOther methods include decomposition of sodium silicate with ammonia salts or alkali salts, a method of generating alkaline earth metal silicate from sodium silicate and then decomposing it with acid to form silicic acid, and a method of decomposing sodium silicate with ammonia salts or alkali salts. There are a method of converting silicic acid into silicic acid using an ion exchange phase resin, a method of using natural silicic acid or a silicate, and the like.

As the silica 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.

Among the above-mentioned fine silica powders, those having a specific surface area due to nitrogen adsorption measured by the BET method within the range of 30 m2/g or more (particularly from 50 to 11,400 m2/g) give good results.

As a method for obtaining positively chargeable silica fine powder, the above-mentioned untreated fine silica powder is treated with a silicone oil having an organo group having at least one nitrogen atom in its side chain, or nitrogen-containing silane coupling is used. There is a method of treatment with a chemical agent, or a method of treatment with both.

In the present invention, positively charged silica refers to silica that has a positive triboelectric charge relative to the iron powder carrier when measured by a blow-off method.

As the silicone oil having a nitrogen atom in the side chain used in the treatment of silica fine powder, a silicone oil having at least a partial structure represented by the following formula can be used.

1 2 (wherein R1 represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, R2 represents an alkylene group or a phenylene group, R., R represents hydrogen, an alkyl group, or an aryl group, R, (represents a nitrogen-containing heterocyclic group) The above alkyl group, aryl group, alkylene group, and phenylene group may have an organo group having a nitrogen atom, and may also contain a halogen or the like to the extent that the chargeability is not impaired. It may have a substituent.

Furthermore, the nitrogen-containing silane coupling agent used in the present invention is
It generally has a structure shown by the following formula.

RmSiYn (R represents an alkoxy group or a halogen, Y represents an axon group or an organo group having at least one nitrogen atom, m and n are integers of 1 to 3, and m+
There is a relationship of n=4. ) Examples of the organo group having at least one nitrogen atom include an amino group having an organic group as a substituent, a nitrogen-containing heterocyclic group, or a group having a nitrogen-containing heterocyclic group. Examples of the nitrogen-containing heterocyclic group include an unsaturated heterocyclic group and a saturated heterocyclic group, and known ones can be used. Examples of the unsaturated heterocyclic group include the following.

Examples of the saturated heterocyclic group include the following.

The heterocyclic group used in the present invention is preferably a five-membered ring or a six-membered ring, considering stability.

Examples of such treating agents are apropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, and diethylaminopropyltrimethoxysilane. dibropylaminobrobyl trimethoxysilane, dibutylaminobrobyl trimethoxysilane 1 monobutylaminobrobyl trimethoxysilane 1 dioctylaminobrobyl trimethoxysilane, dibutylaminoprobyl dimethoxysilane, dibutylaminobrobyl monomethoxysilane, Dimethyla-based nophenyltriethoxysilane, trimethoxysilyl-γ
-propylphenylar, trimethoxysilyl γ-
Brobylbenzylamine and the like can be used. Furthermore, as the nitrogen-containing heterocycle, those having the above-mentioned structures can be used. Examples of such derivatives include trimethoxysilyl-γ-propylbiveridine. Examples include trimethoxysilyl-γ-propylmorpholine, trimethoxysilyl-γ-propylimi 15 dazole, and the like.

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 particularly preferably when it is added in an amount of 0.03 to 5%, excellent stability is achieved. It exhibits positive chargeability. The preferred form of addition is 0. It is preferable that 01 to 3% by weight of treated silica fine powder be attached to the surface of the toner particles.

Furthermore, the silica fine powder used in the present invention may be treated with a silane coupling agent and an IA filler such as an organosilicon derivative for the purpose of hydrophobization, if necessary, and a known method may be used. The silicate powder is treated with the above-mentioned processing agent that reacts with or physically adsorbs the silicate powder. Examples of such treatment agents include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, and benzyldimethylchlorosilane. , prommethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercabutane, trimethylsilylmercabutane, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane , dimethyldimethoxysilane, diphenyljethoxysilane,
Hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and one unit each having 2 to 12 siloxane units per molecule and located at the terminal end. 51 of
Examples include dimethylborisiloxane containing a hydroxyl group bonded to . These are 1 type or 2 f! Used in mixtures of 11 or more.

Finally, the degree of hydrophobicity of the treated silica fine powder was determined to be 30 as measured by methanol titration test.
When hydrophobized to show a value in the range of .about.80, the triboelectric charge of a developer containing such a silica powder exhibits sharp and uniform positive chargeability, which is preferable. Here, in the methanol titration test, the degree of hydrophobization of the silica fine powder having a hydrophobized surface is confirmed.

The ``methanol titration test'' specified herein for evaluating the degree of hydrophobicity of the treated silica fine powder is carried out as follows. Sample silica fine powder 0.2g in capacity 250
Add to 50 mj+ of water in a mI2 Erlenmeyer flask. Methanol is titrated from the puret until the entire amount of silica is wetted. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. 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.

Colorants used in the present invention include carbon black, lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G1 Rhodamine 6G, calco oil blue chrome yellow, quinacridone, penzidine yellow, Conventionally known dyes and pigments such as rose bengal, triarylmethane dyes, monoazo dyes, and disazo dyes and pigments can be used in combination or in combination.

Examples of the resin used in the present invention include monopolymers of styrene and its substituted products such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene;
Chlorstyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-α-methyl chloromethacrylate copolymer , styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene Styrenic copolymers such as acrylonitrile-indene copolymers; polyvinyl chloride, phenolic resins, naturally modified phenolic resins, natural resin-modified maleic acid resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyesters Resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terbene resin, coumaron indene resin,
Petroleum-based resin etc. can be used.

Further, crosslinked styrenic copolymers are also preferred binder resins.

Examples of comonomers for the styrene monomer in the styrenic copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, and methacrylate. Acid, monocarboxylic acid having a double bond such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc., or substituted products thereof; e.g., maleic acid, butyl maleate dicarboxylic acids having 20 double bonds, such as methyl maleate, dimethyl maleate, etc.; vinyl esters, such as vinyl chloride, vinyl acetate, vinyl benzoate; such as ethylene, propylene, butylene, etc. Vinyl monomers such as ethylene olefins such as; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, etc.; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. Can be used alone or in combination.

As the crosslinking agent, derivatives having two or more polymerizable double bonds are mainly used, such as aromatic divinyl derivatives such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate and ethylene glycol diacrylate. Carboxylic acid esters having two double bonds such as methacrylate and 1,3-butanediol dimethacrylate; divinyl derivatives such as divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and having three or more vinyl groups. derivative;
may be used alone or as a mixture.

In addition, when using a pressure fixing method, it is possible to use a binder resin for pressure fixing toners, such as polyethylene,
Examples include polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, paraffin, and the like.

Furthermore, the toner of the present invention is used in combination with a carrier. As carriers that can be used in the present invention, known carriers can be used, such as magnetic powders such as iron powder, ferrite powder, nickel powder, glass beads, etc., and carriers whose surfaces are treated with resin etc. Those who have done so will be listed.

In addition, examples of the resin that coats the carrier surface include styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, acrylic ester copolymer, methacrylic ester copolymer, silicone resin, fluorine-containing resin, Polyamide resin, ionomer resin, polyphenylene sulfide resin, etc. or a mixture thereof can be used.

Further, the toner for electrostatic charge development of the present invention can also be used as a magnetic toner by containing a magnetic material. Magnetic materials used include iron oxides such as magnetite, gamma iron monoxide, ferrite, and iron-rich ferrite; iron, cobalt,
Metals such as nickel or these metals and aluminum,
Examples include alloys with metals such as cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

It is desirable that these magnetic materials have an average particle diameter of about 0.1 to 1 μm, preferably about 0.1 to 0.5 μm, and the amount to be contained in the magnetic toner is 40 to 100 parts by weight per 100 parts by weight of the binder resin component. 150 parts by weight, preferably 60-12
It is 0 parts by weight.

The toner of the present invention may contain additives, if necessary. Examples of additives include lubricants such as zinc stearate, abrasives such as cerium oxide and silicon carbide, flow agents such as aluminum oxide, anti-caking agents, and conductive agents such as carbon black and tin oxide. There is an imparting agent.

Further, fine powder of a fluorine-containing polymer such as fine powder of polyvinylidene fluoride is also a preferable additive from the viewpoint of fluidity, polishability, charging stability, and the like.

In addition, in order to improve mold releasability during hot roll fixing, waxy substances such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, Sasol wax, paraffin wax, etc.
It is also one of the preferred embodiments of the present invention to add about 5% by weight to the toner.

In manufacturing the toner according to the present invention, the toner constituent materials as described above are sufficiently mixed using a bowl kneader or other mixer, then thoroughly kneaded using a heat kneader such as a hot roll kneader or an extruder, and then cooled. After solidification, a method of obtaining a toner by mechanical crushing and classification is preferable.Other methods include a method of obtaining a toner by dispersing constituent materials in a binder resin solution and then spray drying; Polymerization method toner manufacturing method in which monomers to constitute the binder resin are mixed with predetermined materials to form an emulsified suspension and then polymerized to obtain a toner: Alternatively, in a so-called microcapsule toner consisting of a core material and a shell material, The following methods can be applied: a method in which a predetermined material is contained in the core material, the shell material, or both. Furthermore, the toner according to the present invention can be produced by sufficiently mixing desired additives with a mixer such as a Henschel mixer, if necessary.

The toner of the present invention can be used in all conventionally known methods for developing electrostatic charge images in electrophotography, electrostatic recording, electrostatic printing, and the like.

The styrene copolymer having a phosphonium salt in the side chain of the present invention is colorless and has good positive triboelectric charging properties. Also,
By externally adding the positively chargeable silica fine powder, it is possible to prevent the toner carrier from being contaminated by the styrene copolymer having a phosphonium salt in the side chain, and it is also possible to improve the density uniformity of the evening image.

Therefore, the toner of the present invention is less likely to cause image quality deterioration due to continuous copying and can provide images with excellent density uniformity.

[Example 7] The present invention will be specifically explained below using Examples, but the present invention is not limited thereto. Note that all parts in the following formulations are parts by weight.

After thoroughly mixing the above materials in a blender, they were kneaded in a twin-screw kneading extruder set at 150°C.

The obtained kneaded material was cooled and coarsely pulverized using a cutter mill, and then finely pulverized using a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type wind classifier to refine the classified powder.

Furthermore, the obtained classified powder was strictly classified and removed at the same time to remove ultra-fine powder and coarse powder using a multi-division classification device (elbow jet classifier manufactured by Nippon Steel Mining Co., Ltd.) using the Coanda effect, resulting in a volume average particle size of 8.7 μm. A black fine powder was obtained.

Add 100 parts of this black fine powder to positively charged hydrophobic dry silica (
BET specific surface area: 200 m27 g) was added and mixed in a Henschel mixer to obtain a positively chargeable one-component magnetic toner.

The obtained magnetic toner was transferred to a commercially available electrophotographic copying machine NP-35.
25 (manufactured by Canon Inc.), a 5,000 copy test was conducted.

As a result, a clear image with an image density of 1.30 and good resolution with little fog was obtained from the initial stage. Further, the image density after copying 5,000 sheets was also good at 1.33, and no decrease in density or deterioration of image quality was observed.

Example 2 100 parts of styrene/butyl acrylate copolymer 27 The above materials were thoroughly mixed in a blender and then kneaded in a twin-screw kneading extruder set at 150°C.

The obtained mixed material was cooled, coarsely pulverized with a cutter mill, and then finely pulverized with a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type wind classifier to refine the classified powder.

Furthermore, the obtained classified powder was strictly classified and removed at the same time to remove ultra-fine powder and coarse powder using a multi-division classifier that utilizes the Coanda effect (Elbowjet classifier manufactured by Nippon Steel Mining Co., Ltd.), resulting in a volume average particle diameter of 1.8 μm. A black fine powder was obtained.

Add 100 parts of this black fine powder to positively charged hydrophobic dry silica (
BET specific surface area 200 m2/g) was added and mixed in a Henschel mixer to obtain a positively charged one-component magnetic toner.

The obtained magnetic toner was transferred to a commercially available electrophotographic copying machine Nl'-5.
540 (manufactured by Canon Inc.), a 10,000 copy test 28 was conducted.

As a result, a clear image with an image density of 1.34 and less fog was obtained from the initial stage. Further, the image density after copying 10,000 sheets was as good as 1.31, and no decrease in density or deterioration in image quality was observed.

After thoroughly mixing the above materials in a blender, they were kneaded in a twin-screw kneading extruder set at 150°C.

The obtained mixed material was cooled, coarsely pulverized with a cutter mill, and then finely pulverized with a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type wind classifier to refine the classified powder.

Furthermore, the obtained classified powder was strictly classified and removed at the same time to remove ultrafine powder and coarse powder using a multi-division classification device (Elbow Jet classifier manufactured by Nippon Steel Mining Co., Ltd.) using the Coanda effect, resulting in a volume average particle diameter of 10.5 μm. A blue fine powder was obtained.

100 parts of the obtained blue fine powder was mixed with dry silica (16
0m27g) were mixed to obtain a toner.

Next, 5 parts of the obtained toner was added to 100 parts of a fluorine-acrylic coated ferrite carrier having an average particle size of 65 μm.
These parts were mixed to prepare a developer.

This developer is applied to a commercially available copying machine (product name NP-5540,
Copying test was carried out using Canon ■.

As a result, a bright blue image with a density of 1.34 was obtained. Even after copying 5,000 sheets, a bright blue image with a density of 1.30 was obtained, and no deterioration in image quality was observed.

Further, density uniformity in solid images was also excellent.

In addition, the amount of triboelectric power obtained by blow-off method of this developer is 3.
1uc/g, and 38μc/g even after copying 5,000 sheets.
Although a slight increase was observed, the results were good.

Comparative Example 1 The blue fine powder obtained in Example 3 was used as a toner without adding silica externally. A developer was obtained in the same manner as in Example 3,
A copy test was conducted.

As a result, a low-density image with a density of 1.01 was obtained from the beginning, and it increased to 1.21 in the middle, but the image density gradually decreased, and the image density after 5,000 copies was 0.78. . Friction of developer? I! When n was measured by the blow-off method, it was 22 μc/g initially, but it decreased to 13 μc/g after copying 5,001) sheets.

Ogakiri 1 Using the above materials and the same method as in Example 3, a red fine powder with a volume average particle size of 9.8 μm was obtained.

0.6 part of the dry silica used in Example 2 was mixed with 100 parts of the obtained red fine powder to obtain a toner.

Next, a developer was obtained in the same manner as in Example 2, and a copying test was conducted.

31 As a result, a bright red image with a density of 1.31 was obtained from the initial stage. No deterioration in image quality was observed even after a 5,000 copy test, and density uniformity in solid images was also excellent. The amount of triboelectric charge by the blow-off method is 5 at 29 μc/g.
Almost no deterioration was observed even after running for ,000 sheets.

32 images were obtained. No deterioration in image quality was observed even after a 5,000 copy test, and density uniformity in solid images was also excellent. The amount of triboelectric charge determined by the blow-off method was 30 μc/g, and almost no decrease was observed even after 5,000 sheets were used.

Using the above materials and in the same manner as in Example 3, a fine green powder with a volume average particle size of 10.3 μm was obtained.

0.6 part of the dry silica used in Example 2 was mixed with 100 parts of the obtained green fine powder to obtain a toner.

Next, a developer was obtained in the same manner as in Example 3, and a copying test was conducted.

As a result, a bright green color with a concentration of 1.28 was obtained from the beginning.The above materials were thoroughly mixed in a blender and then kneaded in a twin-screw kneading extruder set at 150°C.

The obtained K-kneaded product was cooled, coarsely pulverized with a cutter, and then finely pulverized with a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type wind classifier.

Furthermore, the obtained classified powder was thoroughly classified and removed at the same time using a multi-division classification device (Elbowjet classifier manufactured by Nippon Steel Mining Co., Ltd.) that utilizes the Coanda effect, and the volume average particle size was 8.5 μm.
A fine powder of m was obtained.

Positively charged hydrophobic dry silica (
BET specific surface area: 200 m27 g) was added and mixed in a Henschel mixer to obtain a positively chargeable toner.

Next, 4 parts of the obtained toner were mixed with 100 parts of a fluorine-acrylic coated ferrite carrier having an average particle size of 65 μm to prepare a developer.

This developer was applied to a commercially available color electrophotographic copying machine CLC-1.
A copying test was conducted using a modified machine manufactured by Canon Corporation (manufactured by Canon ■) in which the OPC photosensitive drum was replaced with a non-quality silicone drum.

As a result, a bright blue image with a density of 1.37 was obtained from the initial stage, and no deterioration was observed after 5,000 copies were made.

Example 7 5 parts of the copper phthalocyanine pigment (C.I. Pigment Blue 15) in Example 6 was replaced with a quinacridone pigment (C.I.
．． Pigment Red 122) A fine powder with a volume average particle size of 8.6 μm was obtained in the same manner as in Example 6 except that the amount was changed to 1 part, and silica was further mixed to obtain a positive f-electrode toner k0. A developer was prepared by mixing carriers in the same ratio.

This developer was subjected to a copying test in the same manner as in Example 6. As a result, a bright magenta image with a density of 1.36 was obtained from the initial stage. No deterioration in image quality was observed even after 5,000 copies were made.

Example 8 5 parts of the copper phthalocyanine pigment (C.I. Pigment Blue 15) given in Example 6 was added to C.I. I. A fine powder having a volume average particle diameter of 8.9 μm was obtained in the same manner as in Example 6 except that 3.5 parts of Pigment Yellow 17 was used, and silica was further mixed therein to obtain a positive f-electronic toner.

Next, the same carrier as in Example 6 was mixed in the same ratio to prepare a developer.

This developer was subjected to a copying test in the same manner as in Example 6. As a result, a bright yellow image with a density of 1.34 was obtained from the initial stage. No deterioration in image quality was observed even after 5,000 copies were made.

Example 9 35 A fine powder with a volume average particle diameter of 8.2 μm was obtained in the same manner as in Example 6 except that 5 parts of the copper phthalocyanine pigment (C.I. Pigment Blue 15) in Example 6 was replaced with 3 parts of carbon black. Furthermore, silica was mixed to obtain a positively charged toner.

Next, the same carrier as in Example 6 was mixed in the same ratio to prepare a developer.

This developer was subjected to a copying test in the same manner as in Example 6. As a result, a bright black image with a density of 1.39 was obtained from the initial stage. No deterioration in image quality was observed even after 5,000 copies were made.

Example 10 11i Cyan, magenta, yellow used in Examples 6 to 9,
When a full-color image was obtained using a black developer, a bright full-color image with excellent color mixing and gradation was obtained.

Sha 18 Ikumi 36 After thoroughly mixing the above materials in a blender, they were kneaded in a twin-screw kneading extruder set at 150°C.

The obtained kneaded material was cooled and coarsely pulverized using a cutter wheel, and then finely pulverized using a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type force classifier to refine the classified powder.

Furthermore, the obtained classified powder was strictly classified and removed at the same time to remove ultra-fine powder and coarse powder using a multi-division classifier (elbow jet classifier manufactured by Nippon Steel Mining Co., Ltd.) that utilizes the Coanda effect. A black fine powder was obtained.

A toner was obtained by mixing 0.4% by weight of silica (140 m2/g) treated with silicone oil modified with an axon group into this black fine powder.

A developer was prepared by mixing 5 parts of this black fine powder with 100 parts of iron powder carrier having an average particle size of 50 to 80 μm. Next, a negative electrostatic image is formed on the OPC photoreceptor by a conventionally known electrophotographic method, and this is developed using the above-mentioned developer using a magnetic brush method to create a toner image, which is transferred to plain paper. , heat-fixed.

The obtained image had a sufficiently high density of 1.38 and was clear. Further, the density was 1.35 even after copying 5,000 sheets, and no decrease in density was observed. Furthermore, the density uniformity of the solid black image was also excellent. When the amount of triboelectric charge was measured using the blow-off method, it was found to be 11.8 μc/g at the initial stage.
After copying 5,000 sheets, it was 10.4 μc/g, and there was no decrease.

Comparative Example 2 A toner was obtained in the same manner as in Example 1l, except that 3 parts of benzylmethylhexadecyl ammonium chloride was used instead of 2 parts of compound (5) used in Example 11. An image was obtained in the same manner as in Example 11 using this toner.

As a result, the image density was slightly low at 1.15 from the beginning, and fog was noticeable. Although 5,000 sheets were continuously copied, no increase in image density was observed. The amount of triboelectric charge measured by the blow-off method was as low as 7.8 μc/g.

[Effects of the Invention] As described above, according to the positively charged electrostatic image developing toner of the present invention, there is no decrease in image density due to an increase in the number of copies, and high quality images without fogging etc. can be stably produced. Obtainable.

Claims (3)

[Claims] (1) A positively chargeable electrostatic image characterized by adding positively chargeable silica fine powder to fine powder particles comprising at least a copolymer represented by the following general formula [I], a colorant, and a binder resin. Toner for development. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] (However, R^1, R^2, R^3 are hydrogen, alkyl groups,
It represents either an aryl group or an aralkyl group, and may be the same or different. X represents an anion. l is 1
Indicates an integer of ~8. m/n=20/80 to 1/99,
Shows the polymerization ratio. ) (2) The positively chargeable silica fine powder has the following general formula [II]
2. The toner for developing positively charged electrostatic images according to claim 1, wherein the toner is obtained by treating fine silica powder with a silane compound represented by: R_mSiY_n[II] (However, R represents an alkoxy group or halogen, m is 1
is an integer of ~3, Y represents an amino group or an organo group having at least one nitrogen atom, and n is m+n=4
is an integer from 1 to 3 that satisfies the following. ) (3) The positively chargeable silica fine powder is obtained by treating the silica fine powder with a silicone oil having an organo group or an amino group having a nitrogen atom in a side chain. The positively chargeable electrostatic image developing toner described above.