JPH0269768A - Nourishing toner for electrostatic image development - Google Patents

Abstract

PURPOSE:To uniformize the triboelectrostatic charge quantity between toner particles and to obtain a high-grade image by making combination use of a specific dye and positive chargeable fine silica powder. CONSTITUTION:The positive chargeable magnetic toner for developing electro static charge images contains the dye expressed by the formula 1 or the pigment formed by chelating this dye as a positive charge control agent and is externally added with the positive chargeable fine silica powder. In the formula, R<1> to R<6> denote a hydrogen atom, substd. or unsubstd. alkyl group, substd. or unsubstd. aryl group which may be respectively the same as or different from each other; A<-> denotes a sulfuric acid ion, nitric acid ion, etc. The triboelectrostatic charge quantity between the toner particles or between the toner and a toner carrier such as sleeve is stabilized in this way and the stable image which is not affected by a change in temp. and humidity is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a new toner for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, and the like.

[Prior Art] Conventionally, as an electrophotographic method, U.S. Patent No. 2,297°69
1, Special Publication No. 42-23910, and Special Publication No. 4
Various methods are described in Japanese Patent Publication No. 324748, etc., but these methods basically provide a -like electrostatic charge on a photoconductive insulating layer and irradiate the insulating layer with a light image to remove the electrostatic charge. A latent image is formed, and then the latent image is developed and visualized using a fine powder called toner using the technology, and the powder image is transferred to paper or the like as necessary, and then fixed by heat, pressure, or solvent vapor. It is something to do.

The developing methods applied to these electrophotographic methods include:
Broadly speaking, there are dry development methods and wet development methods. The former method is further divided into a method using a two-component developer and a method using a -component developer. Two-component developing methods include:
Magnetic brush method using iron powder carrier, beads and
There are a cascade method using a carrier, a fur brush method using fur, etc.

In addition, those belonging to the -component type development method include a powder cloud method in which toner particles are sprayed, and a contact development method (contact development, or (also referred to as toner development), jumping development method in which toner particles are not brought into direct contact with the electrostatic latent image surface, but are charged and flown toward the latent image surface by the electric field of the electrostatic latent image; and magnetic conductive method. There is the MagneDry method, which develops by bringing a toner into contact with the electrostatic latent image surface.

Conventionally, toners used in these development methods are fine powders in which dyes and pigments are dispersed in natural or synthetic resins. Particles obtained by pulverizing the particles to about 1 to 30 particles are used as toner. As the magnetic toner, one containing magnetic particles such as Magnetai I 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.

Further, the toner is made to hold a positive or negative charge depending on the polarity of the electrostatic latent image to be developed.

In order to make the toner hold an electric charge, it is also possible to use the triboelectricity of the resin that is a component of the toner, but since the toner's chargeability is small with this method, the image obtained by development is prone to fogging and is unclear. Become something. Therefore, in order to impart desired triboelectric charging properties to toners, dyes, pigments, and even charge control agents that impart charging properties are added to the toners.

Among the charge control agents known in the art today, the positive charge control agent is nigrosine dye (Japanese Patent Publication No. 41
-2427 Publication), azine dye (Special Publication No. 42-18
27), vinyl polymers and condensation polymers containing amino groups (Japanese Patent Publication No. 53-13284), 4
class ammonium salts (JP-A-132-192755, JP-A-82-87974, JP-A-82-539)
Publication No. 44, etc.).

On the other hand, the charge control agent must have sufficient triboelectric charge, little environmental variation in triboelectric charge, good storage stability, good thermal stability, and good dispersibility in the binder resin. However, there is no conventionally known charge control agent that satisfies all of these requirements.

Also, Special Publication No. 57-3940, Special Publication No. 58-94
No. 15, JP-A-54-84732, JP-A-Sho 5
No. 8-46248 and Japanese Patent Application Laid-open No. 81-124955 disclose that triphenylmethane dyes and dyes obtained by laking them can be used satisfactorily in two-component nonmagnetic toners.

However, many of these triphenylmethane dyes or laked pigments have a low triboelectric charge and cannot be used in magnetic toners.Also, triphenylmethane dyes and lake pigments that have a sufficient triboelectric charge cannot be used. However, toners using these materials tend to contaminate toner carriers such as sleeves, and also tend to cause fogging.

[Problem 8 to be Solved by the Invention] An object of the present invention is to provide a positively charged magnetic toner for developing electrostatic images that solves the above-mentioned problems.

Furthermore, it is an object of the present invention to stabilize the amount of triboelectric charge between toner particles or between toner and a toner carrier such as a sleeve.
To provide a developer capable of reproducing stable images unaffected by changes in temperature and humidity.

[Means and effects for solving the problems] The positively charged magnetic toner for developing electrostatic images of the present invention contains a dye represented by the general formula (1) or a pigment obtained by laked dye thereof as a positive charge control agent, Moreover, it is characterized by the external addition of positively chargeable silica fine powder.

[In the formula, 1lil, R2, R3, R4, R5, 117
6 is a hydrogen atom which may be the same or different from each other,
Represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. R7, )7B, )79 each represent a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, which may be the same or different from each other; A- is a sulfate ion or a nitrate ion;

These are anions such as borate ion, phosphate ion, hydroxide ion, organic sulfate ion, organic sulfonate ion, organic phosphate ion, carboxylate ion, organic borate ion, and tetrafluoroporate. ] As a result of studies to achieve the above object, the present inventors have developed a dye in which the halogen ion of the triarylmethane dye represented by the general formula (1) is replaced with another inorganic anion or an organic anion. found that the amount of positive triboelectric charging increased compared to the case of halogen ions. Furthermore, the inventors have found that by forming the dye into a lake, the hygroscopicity originally possessed by the triarylmethane dye can be improved without any adverse effect on the amount of positive triboelectric charging. Furthermore, the toner containing the dye represented by the general formula (1) and the laked pigment is
The present invention was completed based on the finding that the toner carrier, such as a sleeve, is contaminated, but it can be significantly improved by externally adding positively chargeable silica fine powder to the toner.

In the present invention, examples of compounds of general formula (1) include:
The following can be mentioned:

(Margins below) / \ / HC-CH3 General formula (1) NoRI, R7, R3, R4, R5, R
As the alkyl group and aryl group of 6, R1, and R11, those having carbon fi12 or less are preferable in consideration of ease of synthesis, and )71. The alkyl group and alkoxy group for R8 and R9 preferably have 8 or less carbon atoms in view of ease of synthesis.

Lake formation of the dye is carried out by a known method. For example, an aqueous solution of a lake forming agent is added to an aqueous solution of the dye in acetic acid to precipitate a lake pigment. Alternatively, the extender pigment is suspended in an acetic acid aqueous solution of the dye, and then an aqueous solution of a lake forming agent is added to deposit the lake pigment on the surface of the extender pigment. The lake pigment is filtered, washed with water, and then dried. Note - Examples of the chelating agent include water-soluble salts of phosphotungsten molybdic acid, phosphotungstic acid, phosphomolybdic acid, and water-soluble salts containing complex anions such as ferrocyan and ferricyan.

Organic acid salts can also be used as lake forming agents, but, for example, gallic acid lakes do not have very good charging properties.This is because organic acid lakes have good compatibility between the resin and the lake. This seems to be due to the fact that the properties of the poor resin become noticeable.

Methods for incorporating the dye of the present invention and its lake pigment into the toner include a method of adding it inside the toner and a method of adding it externally. When internally added, the amount of the charge control agent of the present invention is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner manufacturing method, and is not uniquely limited. It is used in an amount of 0.1 to 20 parts by weight, preferably 0.15 to 10 parts by weight. When externally added, 0.0 parts per 100 parts by weight of resin.
The amount is preferably 1 to 10 parts by weight, and it is preferably mechanochemically fixed to the surface of the base particle.

Further, conventionally known charge control agents can be used in combination with the charge control agent of the present invention to the extent that they do not have any adverse effects.

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 silicon halide compounds.For example, it is a method that utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen hydrogen. The reaction formula is as follows.

5iCRs + 2 R2+ 02→5i02+ 4
HCR also uses other metal halide compounds such as aluminum chloride or titanium chloride in this manufacturing process.
It is also possible to obtain composite fine powders of silica and other metal oxides by using them together with silicon halogen compounds, and these are also included.

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 a general reaction formula (the reaction formula is omitted below).

Na2O・XSiO2+HCj) +H20−*SiO
2.nH2O+NaCf1 Other methods include decomposition of sodium silicate with ammonia salts or alkali salts, generation of alkaline earth metal silicate from sodium silicate and decomposition with acid to form silicic acid, and ionization of sodium silicate solution. There are methods such as using exchange resin to produce silicic acid, and using natural silicic acid or silicate.

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.

Jll Kusilica fine powder has a specific surface area due to nitrogen adsorption determined by BET method of Δ11 of 30+a2/g or more (especially 5
0 to 400 m2/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 is inappropriate for visualization.

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 a nitrogen-containing silane coupling agent is used. There are two ways to process this:

In the present invention, positively charged silica refers to silica that has a positive tripo 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.

(In the formula, R1 represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, R2 represents an alkylene group or a phenylene group, R3* R4 represents hydrogen, an alkyl group, or an aryl group, and R5 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, or may have a substituent such as a halogen within a range that does not impair chargeability. Also good.

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

R@SiY.

(R represents an alkoxy group or a halogen, Y represents an amino group or an organo group having at least one nitrogen atom, 1m and n are integers of 1 to 3, and m+n=
It is 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 unsaturated heterocyclic groups and saturated heterocyclic groups, 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 in consideration of stability.

Examples of such treatment agents include aminopropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, mono- Butylaminopropyltrimethoxysilane, dioctylaminopropyltrimethoxysilane, dibutylaminopropyldimethoxysilane.

Dibutylaminopropyl monomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamino.

trimethoxysilyl-γ-propylbenzylamino, etc. Furthermore, as the nitrogen-containing heterocycle, those with the above-mentioned structure are used.5 Examples of such compounds include trimethoxysilyl-γ-propylpiperidine, trimethoxysilyl-γ-propylpiperidine, etc. Silyl-γ-propylmorpholine, trimethoxysilyl-γ
- Propylimidazole, etc.

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. A preferred form of addition is that 0.01 to 3% by weight of treated silica fine powder based on the weight of the developer is attached to the surface of the toner particles.

Furthermore, the silica fine powder used in the present invention may be treated with a treatment agent such as a silane coupling agent or an organosilicon compound for the purpose of hydrophobization, if necessary, and a known method may be used. , treated with the above-mentioned treatment agent that reacts with or physically adsorbs the silica fine powder. Examples of such treatment agents include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, and benzyldimethylchlorosilane. , bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyl Dimethoxysilane, diphenyljethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule (terminally There are dimethylpolysiloxanes containing one Si-bonded hydroxyl group in each located unit.These may be used alone or in a mixture of two 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 ~80, the triboelectric charge of the developer containing such fine silica powder becomes sharp and uniformly positive, which is preferable.Here, methanol is used. The titration test is performed to confirm the degree of hydrophobization of the silica fine powder having a hydrophobized surface.

The "methanol titration test" specified herein for evaluating the degree of hydrophobicity of the treated silica fine powder is carried out as follows.
■Add to 50mj7 of water in P's Erlenmeyer flask. Methanol is titrated from the burette until all of the 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.

The effect of the positively chargeable silica fine powder in the present invention is to improve the contamination of toner carriers such as sleeves caused by the charge control agent of the present invention, and to always impart a sufficient amount of triboelectric charge to the toner. Although such a contamination prevention effect can be expected with other fine silica powders, the positively chargeable fine silica powder of the present invention
It was particularly effective. Although the details of this cause are unknown,
This is thought to be because the positively chargeable silica fine powder of the present invention exists in a larger amount on the toner surface after continuous copying than the normal silica fine powder.

Further, one of the characteristics of the charge control agent of the present invention is that the amount of positive triboelectric charge decreases at low temperature and low humidity, and increases at high temperature and high humidity. On the other hand, in the case of the positively chargeable silica fine powder of the present invention, the charge (2) is higher at low temperature and low humidity than at high temperature and high humidity, as in the case of ordinary compounds. Therefore, the magnetic toner for developing an electrostatic image obtained by adding the positively charged electrolytic powder of the present invention to the toner containing the positive charge control agent of the present invention is free from environmental fluctuations in charge resistance. Very few.

This effect is a very unique effect obtained when the positive charge control agent of the present invention and the positively chargeable silica fine powder are used together. It is the fundamental thing.

Next, materials other than those mentioned above that are necessary to form the present invention will be listed.

As the binder resin used in the present invention, all binder resins commonly used as binder resins for toners can be used.

For example, monopolymers of styrene and its substituted products such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers , styrene-acrylic acid ester copolymer, styrene-methacrylic acid 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-7 krylopolymer Styrenic copolymers such as nitrile-indene copolymers; polyvinyl chloride, phenolic resin, naturally modified phenolic 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, terpene resin, coumaron indene resin, petroleum 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. acids, monocarboxylic acids having a double bond such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrinitrile, acrylamide, etc., or substituted products thereof; for example, maleic acid, butyl maleate, Dicarboxylic acids with double bonds and substituted products thereof such as methyl maleate, dimethyl maleate, etc.; vinyl esters such as vinyl chloride, vinyl acetate, vinyl benzoate, etc.; e.g. ethylene, propylene, butylene, etc. Vinyl monomers such as ethylene olefins; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. alone or Two or more are used.

As the crosslinking agent, compounds having two or more polymerizable double bonds are mainly used, such as aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate and ethylene glycol diacrylate. methacrylate, 1,3-butanediol dimethacrylate, etc.
Carboxylic acid esters having the following properties: divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and compounds having three or more vinyl groups; are 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 toner, 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, and paraffin.

Furthermore, the magnetic toner of the present invention contains a magnetic material that may also serve as a colorant. The magnetic materials contained in the magnetic toner of the present invention include magnetite, γ-iron oxide, ferrite, iron oxide of iron-rich ferrite M: metals such as iron, Konoheld, and nickel, or these metals and aluminum, cobalt, Examples include alloys with metals such as copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

These ferromagnetic materials preferably have an average particle size of 0.1 to 0.5 ILm, preferably about 0.1 to 0.5 ILm, and the amount contained in the magnetic toner is 40 to 150 parts by weight per 100 parts by weight of the resin component. Parts by weight, preferably resin component 100
EiO-120 parts by weight.

In addition, in order to obtain good development characteristics, the magnetic toner of the present invention has a residual magnetization σ of 0.5 to 6 etsu/g, preferably 1 to 5 emu/g, and a saturation magnetization σ of 10
~40 emu/g, and the coercive force He preferably satisfies the magnetic properties of 20 to 100 days (Oe) (in both cases, the measured magnetic field is IKOe).

The magnetic toner of the present invention may be mixed with additives as required. Examples of additives include lubricants such as zinc stearate, abrasives such as cerium oxide and silicon carbide, and fluids such as aluminum oxide. Examples include conductivity imparting agents, anti-caking agents, and conductivity imparting agents such as carbon black and tin oxide.

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 wt% to the magnetic toner.

In producing the magnetic toner according to the present invention, the above-mentioned magnetic toner constituent materials are thoroughly mixed using a ball mill or other mixer, then thoroughly kneaded using a heat kneader such as a hot roll kneader or an extruder, and then cooled and solidified. (2) A method of obtaining a magnetic toner by mechanical crushing and classification is preferable, and another method is a method of obtaining a magnetic toner by dispersing constituent materials in a binder resin solution and then spray drying;
Alternatively, a polymerization toner manufacturing method in which monomers to constitute the binder resin are mixed with a predetermined material to form an emulsified suspension and then polymerized to obtain a magnetic toner; In the capsule toner, methods such as a method of containing a predetermined material in the core material, the shell material, or both can be applied. Furthermore, the magnetic 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 magnetic toner of the present invention can be used for one-component development for converting electrostatic charge images into WJ images in quasi-photography, electrostatic recording, electrostatic printing, etc. by conventionally known means. .

The magnetic toner of the present invention is preferably applied to an image forming method in which a latent image is developed while flying the toner from a toner carrier such as a cylindrical sleeve to a latent image carrier such as a photoreceptor. That is, the magnetic toner is given a tripo charge mainly through contact with the sleeve surface, and is applied in a thin layer onto the sleeve surface. The thickness of the thin layer of magnetic toner is formed to be thinner than the gap between the photoreceptor and the sleeve in the development area.

When developing a latent image on the photoreceptor, it is preferable to apply an alternating electric field between the photoreceptor and the sleeve, and then cause the magnetic toner having a tripo charge to fly from the sleeve to the photoreceptor.

Examples of the alternating electric field include a pulsed electric field, AC/Haas, or a synergistic combination of AC and DC bias.

[Examples] Hereinafter, the present invention will be specifically explained using Examples, but these are not intended to limit the present invention in any way. In addition, all parts in the following formulations are; P, Qi, parts.

Example 1 The materials listed in L were thoroughly mixed in a blender, and then 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 is strictly classified and removed in the same plane to remove ultrafine powder and coarse powder using a multi-division classifier that utilizes the Coanda effect (Elbowjet classifier manufactured by Iron Mining Co., Ltd.) 10.54 m of black fine powder (magnetic toner) was obtained.

To 100 parts of the obtained black fine powder magnetic toner was added 0.0% of positively charged hydrophobic dry silica (BET specific surface: 1200 m2/g).
5 parts were added and mixed in a Henschel mixer to form a positively chargeable one-component magnetic toner.

The obtained magnetic toner was transferred to Ichihara's electrophotographic copying machine NP-3.
525 (manufactured by Canon ■) is 10. I did a Goo copy test. A clear image with an image density of 1.38 was obtained from the initial stage, and a good image with an image density of 1.36 was obtained even after running on 10,000 sheets.

Table 1 also shows the amount of triboelectric charge before and after external addition of positively charged hydrophobic dry silica: 32.5°C - 85%, 23°C - 10%,
10 parts of magnetic toner per 90 parts of iron powder (75 to 50 gm), showing the results measured under various environments at 15°C - 10%.
After mixing parts under each environment, measurements were made by blow-off method.

As is clear from the results, the amount of triboelectric charge of the magnetic toner after external addition of silica shows almost the same value in all environments.

Example 2 Same as Example 1 except that 4 parts of the phosphorous tungsten molybdic acid lake pigment of Compound Example (1) in Example 1 was changed to 15 parts of phosphorous tungsten molybdic acid lake pigment of Compound Example (2). The toner was obtained and a copy test was conducted.

Good images with an image density of around 1.35 were always obtained.

In addition, friction of magnetic toner after external addition of silica;
had little environmental dependence.

Example 3 A toner was obtained and copied in the same manner as in Example 1, except that 4 parts of the phosphorous tungsten molybdate lake pigment in the compound example of Example 1 was replaced with 3 parts of the phosphorous tungsten molybdate lake pigment of compound example (3). Tested.

Good results were always obtained with an image density of around 1.35.

Also, JA of magnetic toner after external addition of silica? Rub': iF
'+li? ;: had little environmental dependence.

Example 4 A toner was produced in the same manner as in Example 1, except that 14 parts of the phosphotungsten molybdic acid lake pigment of Example 1 (0) was replaced with 5 parts of the phosphotungsten molybdate lake pigment of Compound Example (4). was obtained and a copying test was conducted.

Image density is always 1, good results after 351iij are t
I was beaten.

Furthermore, the environmental dependence of the triboelectrification 1j of the magnetic toner after the silica coating was small.

Comparative Example 1 A multiplication test was conducted in the same manner as in Example 1 using the magnetic toner of Example 1 to which no externally added hydrophobic silica was added.

The initial images had a density of 1.10, had a lot of fog, and were rough. The degree of C was low due to sleeve I dyeing, and after 100 sheets, it decreased to 0.85.

Comparative Example 2 A toner was obtained in the same manner as in Example 1, except that 0.5 part of dry silica treated with hexamethyldisilazane was added in place of the 1F chargeable hydrophobic dry silica of Example 1, and a copying test was carried out. went.

The density was as low as 0.95, resulting in an image with a lot of fog.

Furthermore, the triboelectric charge j,1 was low under any environment.

Comparative Example 3 Same as Example 1 except that 4 parts of a phosphotungsten molybdate lake pigment of a compound in which the anion of Compound Example ■ was changed from 4-hydroxynaphthylsulfonic acid ion to chloride ion was used instead of Compound Example ■. The toner was obtained and a copy test was performed.

Initially, a clear image without fog with a density of 1.37 was obtained, but the density gradually decreased and the image density after 10,000 copies was 1.03. Also, the fog became slightly more pronounced.

Comparative Example 4 A toner was obtained in the same manner as in Example 1, except that 4 parts of the phosphorous tungsten molybdic acid lake pigment in Compound Example 1 of Example 1 was changed to 5 parts of benzylmethylhexadecyl ammonium fluoride. Tsuda: Initially, images with a density of 1.34 were obtained;
The density after copying 0,000 sheets was 0.91. Also,
Fog was always noticeable.

(The following is a blank space) [Effects of the invention] The present invention has a specific dye (positive charge control agent) and a positive charge control agent. Due to the combined use of toner-based silica fine powder, there is some friction between the toner particles. ij is uniform, and the environmental dependence of triboelectric charge (11) is extremely small.Furthermore, since the toner carrier is less contaminated by the load control agent, the frictional charge tonj1: can be greatly reduced by continuous copying. do not have.

Therefore, stable, high-quality images can always be obtained.

Claims (3)

[Claims] (1) Positively charged silica fine powder is externally added to fine powder particles consisting of at least a dye represented by the following general formula (1) or a pigment obtained by forming a lake thereof, magnetic fine powder, and a binder resin. Magnetic toner for developing electrostatic images. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) [In the formula, R^1, R^2, R^3, R^4, R^5, R
^6 represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, which may be the same or different from each other. R^7, R^8, R^9
A^ represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, which may be the same or different from each other.
- is an anion such as sulfate ion, nitrate ion, borate ion, phosphate ion, hydroxide ion, organic sulfate ion, organic sulfonate ion, organic phosphate ion, carboxylate ion, organic borate ion, tetrafluoroborate, etc. It is an ion. ] (2) Positively chargeable silica fine powder is a silica fine powder with the formula R
_mSiY_n [wherein R represents an alkoxy group or halogen, m represents an integer of 1 to 3, Y represents an amino group or an organo group having at least one nitrogen atom, and n represents 1 where m+n is 4 Indicates an integer between ~3. Claim (1): The product is treated with a silane compound represented by
The magnetic toner for developing an electrostatic image as described above. (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 the side chain (claim (1)).
The magnetic toner for developing an electrostatic image as described above.