JPH0820767B2 - Toner for developing positively charged electrostatic image - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention is for developing a positively chargeable electrostatic charge image for developing an electrostatic latent image in an image forming method such as electrophotography and electrostatic recording. Regarding toner.

[Prior Art] Conventionally, as an electrophotographic method, US Pat. No. 2,297,691,
Various methods are described in JP-B-42-23910 and JP-B-43-24748.

The developing methods applied to these electrophotographic methods and the like are roughly classified into a dry developing method and a wet developing method. The former is further divided into a method using a two-component developer and a method using a one-component developer.

Conventionally, as the toner applied to these dry developing methods,
A fine powder in which a dye or pigment is dispersed in a natural or synthetic resin is used. For example, particles in which a colorant is dispersed in a binder resin such as polystyrene and finely pulverized to about 1 to 30 μm are used as toners. A magnetic toner containing magnetic particles such as magnetite is used. In the case of a system using a two-component developer, the toner is usually used by mixing with carrier particles such as glass beads and iron powder.

Both toners must have a positive or negative charge, depending on the polarity of the electrostatic latent image being developed.

To retain the electric charge in the toner, it is possible to utilize the triboelectric charging property of the resin which is a component of the toner. However, since the toner has a low charging property in this method, the image obtained by development is easily fogged and is not clear. Will be things. Therefore, in order to impart an appropriate triboelectric chargeability to the toner, a dye, a pigment, or a charge control agent that imparts the chargeability is added.

Today, as charge control agents known in the art, nigrosine dyes, azine dyes, triphenylmethane dyes, quaternary ammonium salts, or polymers having a quaternary ammonium salt in the side chain are known. .

[Problems to be Solved by the Invention] However, since those containing these charge control agents easily contaminate the sleeve or the carrier, the toners using them have a reduced triboelectric charge amount as the number of copies increases. , Causes a decrease in image density. Further, a certain type of charge control agent has an insufficient triboelectric charge amount and is easily affected by temperature and humidity, which causes environmental fluctuation of image density. In addition, some charge control agents have poor storage stability, and their triboelectrification ability decreases during long-term storage. Further, since a certain type of charge control agent has a poor dispersibility in a resin, a toner using the charge control agent has a non-uniform triboelectric charge amount between particles and is easily fogged. Also, some charge control agents are colored and cannot be used in color toners.

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

That is, an object of the present invention is to provide a toner for developing a positively chargeable electrostatic charge image, which solves such a problem.

[Means and Actions for Solving the Problems] In the present invention, a colored fine powder containing at least a copolymer represented by the following general formula [I], a coloring agent and a binder resin is mixed with a positively chargeable silica fine powder. The present invention relates to a toner for developing a positively charged electrostatic charge image, which is characterized in that

(However, R ¹ , R ² , and R ³ represent hydrogen, an alkyl group, an aryl group, or an aralkyl group, and may be the same or different. X is Indicates. l shows the integer of 1-8. m / n is 20/80 to 1/99
Indicates the polymerization ratio. A styrene copolymer having a phosphonium salt in its side chain has a high positive triboelectric charging property and is colorless, so that it is suitable as a charge control agent for color toners. Moreover, as a result of the study by the present inventors, it was found that the triboelectric charge amount of the styrene copolymer having a phosphonium salt in the side chain changes depending on the type of counter ion. Further, the styrene copolymer having a phosphonium salt in the side chain causes very little contamination of the toner carrier such as the carrier or the sleeve. Therefore, it has been found that the presence of the positive triboelectrically charged fine silica powder on the toner surface is sufficient for improving the contamination of the toner carrier of the styrene copolymer having a phosphonium salt in the side chain.

In addition, the image obtained by the toner containing the styrene copolymer having a phosphonium salt in the side chain is often rough. In particular, in the case of a one-component magnetic toner, it was found that this is due to the disorder of the coated state of the toner on the sleeve. When the fine triboelectric powder having positive triboelectricity was allowed to exist on the toner surface, the toner coated state on the sleeve became uniform, and the image obtained was fine.

Further, the toner containing the styrene copolymer having a phosphonium salt in the side chain had a slightly low triboelectrification rate, so that high-density images could not be obtained from the initial stage. But,
This can also be solved by allowing the positive triboelectrically charged silica fine powder to exist on the toner surface.

As described above, the inventors of the present invention must have positively chargeable silica fine powder in order to take advantage of the excellent properties of the styrene copolymer having a phosphonium salt in the side chain as a positive charge control agent. Then, the present invention was completed.

The molecular weight of the styrene copolymer according to the present invention is not particularly limited because it varies depending on the monomer species, the synthesis method, and the like.
The weight average molecular weight is preferably 5,000 to 50,000. 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 triboelectricity cannot be maintained. Also, the hygroscopicity of the phosphonium salt appears,
Environmental fluctuations in the amount of triboelectricity increase. Weight average molecular weight
If it exceeds 50,000, it may be difficult to obtain fine particles, and the compatibility with the binder resin deteriorates.

As the copolymer represented by the above general formula [I] used in the present invention, those having various structures are selected, and specific examples thereof include the following compound examples (1) and (2). .

Further, it is known from JP-A-63-243964 to incorporate a styrene copolymer having a phosphonium salt in its side chain into a toner. However, these do not mention the effects of the positive triboelectric silica fine powder of the present invention.

Further, the effect of the counter ion of the copolymer represented by the general formula [I], that is, the counter ion is Therefore, as described in the examples below, like a magnetic toner or a toner having a small average particle size,
It does not mention that it has excellent triboelectrification characteristics such that it can be used for toners requiring a higher triboelectrification amount or for toners whose triboelectrification amount becomes too high due to endurance of multiple sheets.

In the present invention, it is indispensable to use the colored fine powder containing the copolymer represented by the general formula [I] having excellent characteristics as a charge control agent for toner in combination with the positively chargeable silica fine powder. However, on the other hand, a toner for developing an electrostatic image having satisfactory performance cannot be obtained.

In the present invention, the styrene copolymer having a phosphonium salt in the side chain is incorporated in the colored fine powder together with the colorant and the binder resin. The amount of these derivatives used is
The type of the binder resin, the presence or absence of additives used as necessary, is determined by the toner manufacturing method including the dispersion method, and is not uniquely limited, but the binder resin 100 is preferable. It is used in an amount of 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on parts by weight. When the above-mentioned copolymer is contained in the colored fine powder, it is possible to fix it on the surface of the toner particles by a mechanochemical method or the like. The special styrene copolymer of the present invention can also be used in combination with a conventionally known charge control agent.

Further, as the silica fine powder which is one component of the developer in the present invention, silica 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 halogen derivative. For example, in a method utilizing a thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen hydrogen, the basic reaction formula is as follows.

SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl In this manufacturing process, for example, by using another metal halogen derivative such as aluminum chloride or titanium chloride together with a silicon halogen derivative, a composite fine powder of silica and another metal oxide is obtained. It is also possible to include them.

On the other hand, as a method for producing the silica fine powder used in the present invention by a wet method, various conventionally known methods can be applied. For example, decomposition of sodium silicate with an acid, if it is shown by a general reaction formula (the following reaction formula is abbreviated), Na ₂ O ・ xSiO ₂ + 2HCl + nH ₂ O → xSiO ₂・ nH ₂ O + 2NaCl Others, ammonium salts of sodium silicate or alkali Decomposition with salts, after generating an alkaline earth metal silicate from sodium silicate, the method of decomposing with acid to silicic acid, the method of converting the sodium silicate solution into silicic acid with an ion exchange resin, natural silicic acid or There is a method of using silicate.

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

Among the above silica fine powders, those having a specific surface area of 30 m ² / g or more (particularly 50 to 400 m ² / g) measured by BET method by nitrogen adsorption give good results.

The positively charged silica fine powder may be obtained by treating the above-mentioned untreated silica fine powder with a silicone oil having an organo group having at least one nitrogen atom in its side chain or a nitrogen-containing silane coupling. There is a method of treating with an agent or a method of treating with both.

In the present invention, the positively chargeable silica is one having a positive triboelectric charge to the iron powder carrier when measured by the blow-off method.

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

(In the formula, R ₁ represents hydrogen, an alkyl group, an aryl group or an alkoxy group, R ₂ represents an alkylene group or a phenylene group, R ₃ and R ₄ represent hydrogen, an alkyl group or an aryl group, and R ₅ Represents a nitrogen-containing heterocyclic group.) The alkyl group, aryl group, alkylene group in the above formula,
The phenylene group may have an organo group having a nitrogen atom, or may have a substituent such as halogen as long as the chargeability is not impaired.

The nitrogen-containing silane coupling agent used in the present invention generally has a structure represented by the following formula.

R _m SiY _n (R represents an alkoxy group or halogen, Y represents an amino 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.
As the nitrogen-containing heterocyclic group, there are an unsaturated heterocyclic group and a saturated heterocyclic group, and known ones can be applied. Examples of the unsaturated heterocyclic group include the following.

Examples of the saturated heterocyclic group include the followings.

The heterocyclic group used in the present invention is preferably a 5-membered ring or a 6-membered ring in view of stability.

Examples of such treating agents include aminopropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, and monobutylsilane. Butylaminopropyltrimethoxysilane, dioctylaminopropyltrimethoxysilane, dibutylaminopropyldimethoxysilane, dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-
γ-propylphenylamine, trimethoxysilyl-γ
-Propylbenzylamine and the like, and the nitrogen-containing heterocycle having the structure described above can be used. Examples of such derivatives include trimethoxysilyl-γ-propylpiperidine and trimethoxysilyl-γ-propylmorpholine. , Trimethoxysilyl-γ-propylimidazole and the like.

The amount of the treated silica fine powder applied is 0.01 to 20% by weight based on the weight of the toner containing the colored fine powder and the positively chargeable silica fine powder, and particularly preferably 0.03 to 5% by weight. It exhibits positive chargeability with excellent stability when added in a weight percentage. To describe a preferable mode of addition, it is preferable that 0.01 to 3% by weight of the treated silica fine powder with respect to the toner weight is attached to the surface of the toner particles.

Further, the fine silica powder used in the present invention may be treated with a silane coupling agent and a treating agent such as an organic silicon derivative for the purpose of hydrophobizing, if necessary, and a known method may be used. , And is treated with the above treating agent that reacts with or physically adsorbs on the silica fine powder. Examples of such treatment agents include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, Brommethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxy. Silane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3
-Diphenyltetramethyldisiloxane, and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and each terminally located unit containing a hydroxyl group bonded to Si. These are one or two
Used in mixtures of more than one species.

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

The "methanol titration test" defined in this specification for evaluating the hydrophobicity of the treated silica fine powder is performed as follows. 0.2 g of the fine silica powder to be tested is added to 50 ml of water in an Erlenmeyer flask having a volume of 250 ml. Methanol is titrated from the burette until the total amount of silica is wet. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed by suspending the total amount of fine silica powder 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.

Examples of the colorant used in the present invention include carbon black, lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6G, chalcoil oil blue, chrome yellow, quinacridone, Conventionally known dyes and pigments such as benzidine yellow, rose bengal, triarylmethane dyes, monoazo dyes and disazo dyes can be used alone or in combination.

Examples of the binder resin used in the present invention include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and their substitution products; styrene-p-chlorostyrene copolymers, styrene-vinyl. Toluene copolymer, styrene-vinylnaphthalene copolymer,
Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl Styrene-based copolymers such as ether copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers; polyvinyl chloride, phenol resins , Natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, Le Pen resins, coumarone-indene resin, petroleum resin, or the like can be used.

A crosslinked styrene copolymer is also a preferable binder resin.

Examples of the comonomer for the styrene monomer of the styrene-based copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid. Acids, monocarboxylic acids having a double bond such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide and the like; or maleic acid, butyl maleate, etc. , A dicarboxylic acid having a double bond such as methyl maleate, dimethyl maleate and the like; and vinyl ester such as vinyl chloride, vinyl acetate, vinyl benzoate, etc .;
Ethylene-based olefins such as propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone: vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; One or two or more monomers are used.

Here, as the cross-linking agent, a derivative having two or more polymerizable double bonds is mainly used, and examples thereof include aromatic divinyl derivatives such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate.
Carboxylic acid esters having two double bonds such as ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; divinyl derivatives such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; and 3 or more vinyls. A derivative having a group;
Are used alone or as a mixture.

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

Further, the toner of the present invention is used as a mixture with a carrier. As the carrier that can be used in the present invention, known carriers can be used, for example, iron powder, ferrite powder, magnetic powder such as nickel powder, glass beads, and the like, and the surface thereof is treated with a resin or the like. The ones that have been done are listed.

Further, as the resin coating the carrier surface, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, acrylic acid ester copolymer,
A methacrylic acid ester copolymer, a silicone resin, a fluorine-containing resin, a polyamide resin, an ionomer resin, a polyphenylene sulfide resin, or the like, or a mixture thereof can be used.

The electrostatic charge developing toner of the present invention can also be used as a magnetic toner by containing a magnetic material. Examples of the magnetic material used include iron oxides such as magnetite, γ-iron oxide, ferrite, and iron-rich ferrite; metals such as iron, cobalt, and nickel, or these metals and aluminum, cobalt, copper, lead, magnesium, tin, Examples thereof include alloys with metals such as zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten and vanadium, and mixtures thereof. These magnetic materials preferably have an average particle size of 0.1 to 1 μm, preferably 0.1 to 0.5 μm, and the amount to be incorporated in the magnetic toner is 40 to 150 parts by weight with respect to 100 parts by weight of the binder resin component. , Preferably 60 to 120 parts by weight.

The toner of the present invention may be mixed with an additive as required. Examples of the additive include a lubricant such as zinc stearate, or an abrasive such as cerium oxide and silicon carbide,
Alternatively, there are fluidity-imparting agents such as aluminum oxide, anti-caking agents, or conductivity-imparting agents such as carbon black and tin oxide.

Fluorine-containing polymer fine powder such as polyvinylidene fluoride fine powder is also a preferable additive from the viewpoints of fluidity, polishing property, charge stability and the like.

In addition, wax-like substances such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, microcrystalline wax, carnauba wax, sazol wax, and paraffin wax are used to improve the releasability at the time of heat roll fixing.
It is also one of the preferred embodiments of the present invention to add about 5 to 5% by weight to the toner.

In producing the toner according to the present invention, the toner constituent materials as described above are thoroughly mixed by a ball mill or other mixing machine, and then thoroughly kneaded by using a heat kneader such as a heat roll, a kneader or an extruder, and solidified by cooling. After that, a method of obtaining a colored fine powder by mechanical pulverization and classification is preferable, and after that, after dispersing the constituent materials in the binder resin solution,
A method for obtaining a colored fine powder by spray drying; or a polymerization toner production for obtaining a colored fine powder by mixing a monomer to form a binder resin with a predetermined material to form an emulsion suspension and then polymerizing the mixture. Or a so-called microcapsule toner (colored fine powder having a microcapsule structure) composed of a core material and a shell material, a method of incorporating a predetermined material into the core material or the shell material, or both of them. It can be applied. Further, if necessary, desired additives can be sufficiently mixed with a mixer such as a Henschel mixer to produce the toner according to the present invention.

The toner of the present invention can be used by any conventionally known means for development for developing an electrostatic charge image 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 triboelectricity. Further, by externally adding the fine powder of positively chargeable silica, it is possible to prevent the toner carrier from being contaminated by the styrene copolymer having a phosphonium salt in its side chain, and further improve the density uniformity of a solid image.

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

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. All parts in the following formulations are parts by weight.

Example 1 The above materials were well mixed with a blender and then kneaded with a twin-screw kneading extruder set at 150 ° C. The obtained kneaded product was cooled, coarsely pulverized by a cutter mill, then finely pulverized by a fine pulverizer using a jet stream, and the finely pulverized powder obtained was classified by a fixed wall type air classifier. A classified powder was prepared.

Furthermore, the obtained finely divided powder is precisely classified at the same time using a multi-division classifier (Elbowjet classifier manufactured by Nittetsu Mining Co., Ltd.) that utilizes the Coanda effect, and the volume average particle size of 8.7 μm is removed. A black fine powder was obtained.

100 parts of this black fine powder is added to positively charged hydrophobic dry silica (B
0.6 part of ET specific surface area 200 m ^{2 /} g) was added and mixed with a Henschel mixer to obtain a positively chargeable one-component magnetic toner.

The obtained magnetic toner is used in a commercially available electrophotographic copying machine NP-3525.
A copy test of 5,000 sheets was performed with (Canon).

As a result, a clear image with good resolution and less fog was obtained from the initial stage. Moreover, the image density after copying 5,000 sheets was as good as 1.33, and no decrease in density or deterioration of image quality was observed.

Comparative Example 1 A one-component magnetic toner was prepared as it was without mixing positively charged hydrophobic dry silica to the black fine powder obtained in Example 1, and a copy test was conducted.

As a result, the initial image density was as low as 1.10 and fog occurred, the image density did not rise even after 5,000 copies, and the image was fragile and fog also occurred.

Comparative Example 2 100 parts of the black fine powder obtained in Example 1 was mixed with 0.6 part of negatively charged hydrophobic dry silica treated with dichlorodimethylsilane (BET specific surface area 200 m ² / g) except that a toner was used. In the same manner as in Example 1, a one-component magnetic toner was prepared,
A copy test was conducted.

As a result, the initial image density was low at 0.7, and the fog was severe, and the durability copying test could not be reached.

Example 2 The above materials were well mixed with a blender and then kneaded with a twin-screw kneading extruder set at 150 ° C. The obtained kneaded product was cooled, coarsely pulverized by a cutter mill, then finely pulverized by a fine pulverizer using a jet stream, and the finely pulverized powder obtained was classified by a fixed wall type air classifier. A classified powder was prepared.

Further, the finely divided powder and coarse powder are simultaneously strictly removed by a multi-division classifier (Elbowjet classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect to obtain the classified powder at a volume average particle size of 11.8 μm. A black fine powder of

100 parts of this black fine powder is added to positively charged hydrophobic dry silica (B
0.4 part of ET specific surface area 200 m ^{2 /} g) was added and mixed with a Henschel mixer to obtain a positively chargeable one-component magnetic toner.

The magnetic toner obtained was used as a commercially available electrophotographic copying machine NP-5540.
(Canon Co., Ltd.) was used to perform a 10,000-sheet copy test.

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 neither density reduction nor deterioration of image quality was observed.

Example 3 The above materials were well mixed with a blender and then kneaded with a twin-screw kneading extruder set at 150 ° C. The obtained kneaded product was cooled, coarsely pulverized by a cutter mill, then finely pulverized by a fine pulverizer using a jet stream, and the finely pulverized powder obtained was classified by a fixed wall type air classifier.

Furthermore, the obtained finely divided powder is precisely classified at the same time with a multi-division classifier (Elbowjet classifier manufactured by Nittetsu Mining Co., Ltd.) that utilizes the Coanda effect, and the volume average particle size is 8.5μ.
m fine powder was obtained.

100 parts of the obtained fine powder was charged with positively charged hydrophobic dry silica (B
0.5 part of ET specific surface area 200 m ^{2 /} g) was added and mixed with a Henschel mixer to obtain a positively chargeable toner.

Then, 4 parts of the obtained toner was mixed with 100 parts of a fluorine-acryl-coated ferrite carrier having an average particle diameter of 65 μm to prepare a developer.

This developer was subjected to a copy test by a modified machine in which a commercially available color electrophotographic copying machine CLC-1 (manufactured by Canon Inc.) was replaced with an amorphous silicon drum as an OPC photosensitive drum.

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

Example 4 A fine powder having a volume average particle diameter of 8.6 μm was obtained in the same manner as in Example 3 except that 5 parts of the copper phthalocyanine pigment (CI Pigment Blue 15) in Example 3 was replaced with 1 part of the quinacridone pigment (CI Pigment Red 122). Then, silica was further mixed to obtain a positively charged toner.

Next, the same carrier as in Example 3 was mixed at the same ratio to obtain a developer.

A copy test was conducted on this developer in the same manner as in Example 3. As a result, a bright magenta image with a density of 1.36 was obtained from the beginning. No deterioration in image quality was observed even after copying 5,000 sheets.

Example 5 The volume average particle diameter is 8.9 μm as in Example 3 except that 5 parts of the copper phthalocyanine pigment (CI Pigment Blue 15) in Example 3 is replaced with 3.5 parts of CI Pigment Yellow 17.
To obtain positively charged toner.

Next, the same carrier as in Example 3 was mixed at the same ratio to obtain a developer.

A copy test was conducted on this developer in the same manner as in Example 3. As a result, a bright yellow image with a density of 1.34 was obtained from the beginning. No deterioration in image quality was observed even after copying 5,000 sheets.

Example 6 A fine powder having a volume average particle size of 8.2 μm was obtained in the same manner as in Example 3 except that 5 parts of the copper phthalocyanine pigment (CI Pigment Blue 15) in Example 3 was changed to 3 parts of carbon black, and silica was further mixed. A positively charged toner was obtained.

Next, the same carrier as in Example 3 was mixed at the same ratio to obtain a developer.

A copy test was conducted on this developer in the same manner as in Example 3. As a result, a bright black image with a density of 1.39 was obtained from the beginning. No deterioration in image quality was observed even after copying 5,000 sheets.

Example 7 Cyan, magenta, yellow used in Examples 3 to 6,
When a full color image was obtained using the black developer, a vivid full color image excellent in color mixture and gradation was obtained.

Comparative Example 3 The above materials were well mixed with a blender and then kneaded with a twin-screw kneading extruder set at 150 ° C. The obtained kneaded product was cooled, coarsely pulverized by a cutter mill, then finely pulverized by a fine pulverizer using a jet stream, and the finely pulverized powder obtained was classified by a fixed wall type air classifier. The classified powder was purified.

Furthermore, the finely divided powder and coarse powder are simultaneously strictly removed with a multi-division classifier (Elbowjet classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect to obtain a black powder with a volume average particle size of 11.6 μm. A fine powder was obtained.

0.4% by weight of silica (BET specific surface area 140 m ² / g) treated with amino group-modified silicone oil was mixed with this black fine powder to obtain a toner.

For 100 parts of iron powder carrier with an average particle size of 50-80 μm,
The black fine powder was mixed at a ratio of 5 parts to prepare a developer. Then, a negative electrostatic image is formed on the OPC photosensitive member by a conventionally known electrophotographic method, and this is developed by the magnetic brush method using the above-mentioned developer to form a toner image, which is transferred to plain paper. , Heated and fixed.

As a result, the image density was 1.15 from the beginning, which was slightly low, and the fog was noticeable. After continuous copying of 5,000 sheets, no increase in image density was observed. When the triboelectric charge was measured by the blow-off method, it was as low as 7.8 μC / g.

[Advantages of the Invention] As described above, according to the toner for developing a positively chargeable electrostatic image of the present invention, the image density does not decrease due to an increase in the number of copies, and a high-quality image free from fog is stably obtained. Obtainable.

Claims (5)

[Claims] 1. A positively chargeable static charge characterized by mixing a finely charged silica powder and a colored fine powder containing at least a copolymer represented by the following general formula [I], a colorant and a binder resin. Toner for charge image development. (However, R ¹ , R ² , and R ³ represent hydrogen, an alkyl group, an aryl group, or an aralkyl group, and may be the same or different. X is Indicates. l shows the integer of 1-8. m / n is 20/80 to 1/99
Indicates the polymerization ratio. ) 2. The positively chargeable silica fine powder according to claim 1, which is obtained by treating the fine silica powder with a silane compound represented by the following general formula [II]. Toner for developing electrostatic image. R _m SiY _n [II] (wherein R represents an alkoxy group or halogen, and m is 1
Is an integer of 3 to 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 of 1 to 3 that satisfies ) 3. The positively-chargeable silica fine powder is obtained by treating the fine silica powder with a siquicorn oil having a nitrogen atom-containing organo group or amino group in its side chain. The toner for developing a positively charged electrostatic charge image according to claim 1. 4. The colored fine powder contains a magnetic substance as a coloring agent, and a magnetic toner is formed by mixing with the positively charged silica fine powder. Toner for developing a positively charged electrostatic image. 5. The toner for developing a positively charged electrostatic image according to claim 1, wherein the toner is used as a color toner.