JP2673564B2 - Positively chargeable toner - Google Patents

Description

The present invention relates to a toner used as a developer for developing an electrostatic charge image in electrophotography, electrostatic recording, electrostatic printing and the like. More specifically, in a direct or indirect electrophotographic development method, a positive electrostatic charge image is uniformly and positively charged to visualize a negative electrostatic charge image or a positive electrostatic charge image by reversal development to give a high quality image. The present invention relates to a chargeable toner.

[Prior Art] Conventionally, a number of methods are known as electrophotographic methods, such as US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. ,
An electrostatic latent image is formed on a photoconductor by various means using a photoconductive substance, then the latent image is developed with toner, and the toner image is transferred to a transfer material such as paper as necessary. After that, it is fixed by heating, pressure or solvent vapor to obtain a copy. Further, when there is a step of transferring the toner image, a cleaning step for removing the residual toner is usually provided. Further, among dry toners used for these electrophotography, a two-component toner using a carrier and a one-component toner containing a magnetic component are known. One-component magnetic toners have recently been widely used because the developing device can be simplified and maintenance is easy.

In general, as a one-component magnetic toner used in dry electrophotography, a fine powder in which magnetite, a charge control agent, a lubricant, and the like are dispersed in a binder resin made of a natural or synthetic resin has been used.

Examples of positive charge control agents contained in such toners include quaternary ammonium compounds and organic dyes, particularly basic dyes and salts thereof, and nigrosine base and nigrosine are often used as positive charge control agents.
These are usually added to a thermoplastic resin, melt-dispersed under heating, finely pulverized, and adjusted to an appropriate particle size as required, before use.

However, these charge control agents are liable to cause a change in charge controllability due to mechanical shock, friction, changes in temperature and humidity conditions, and the like.

Therefore, when a toner containing these as a charge control agent is developed using a copying machine, the toner may deteriorate during durability as the number of copying increases.

In particular, when a nigrosine dye is used, the charge imparting member such as the developing sleeve is easily contaminated, and the density is likely to decrease due to an increase in the amount of charge under low temperature and low humidity, and there are many images.

For example, JP-A-49-51951, 54-134441, and 54
-158932, 56-164349, 57-119364, 58-
No. 9154, No. 58-98742, No. 60-169857, No. 62-71968
No. 62-87974 and the like disclose a method of using a quaternary ammonium salt, but a two-component toner using a carrier was able to obtain a practically sufficient image. However, when these are used for the one-component magnetic toner, they have the drawback of lower density and more fog than nigrosine, and the image density is low especially under high temperature and high humidity.

Further, when nigrosine is used, there is a problem that the sleeve is easily contaminated, and the latitude of selecting other materials constituting the toner is extremely narrow.

Further, in JP-A-61-282850, in a non-magnetic two-component toner, a quaternary ammonium salt and stearic acid are used together to achieve charging stability, but a fatty acid alone has a too low melting point to form a toner. Dispersion is poor, and it slips on the wall and shaft of the kneading machine during kneading, which also hinders the dispersion of magnetic substances, pigments, lubricants, etc., resulting in a toner with a lot of fog.

As a method for solving these problems, Japanese Patent Publication No. 59-11901
Japanese Unexamined Patent Publication (Kokai) publication discloses a method in which basic nigrosine is modified with a higher fatty acid to be used as a charge control agent, but it is difficult to control the charge amount, and sometimes the charge becomes excessive and scatters on the image to cause rattling.

Further, the reflection power on the image sleeve is increased, which may cause a decrease in density or unevenness in the sleeve coat.

This phenomenon is remarkable in low-humidity and high-speed machines, and it is inevitable that image defects occur.

Further, JP-A-59-137955 proposes a method of containing a positive charge control agent and a fatty acid derivative to prevent contamination of a sleeve, a photoreceptor or the like with toner and to give a uniform positive chargeability to the toner. There is.

Although this method is effective in preventing contamination, it still tends to be overcharged. As a result of intensive investigations by the present inventors, as a result, the quaternary ammonium salt and the quaternary ammonium salt that have been conventionally used as positive charge contracting agents The present invention has been found that the above-mentioned problems can be solved by using a specific fatty acid metal salt having a higher chargeability than a salt as a positive charge control agent in a specific ratio.

[Problems to be Solved by the Invention] An object of the present invention is to provide a magnetic toner that always provides high-quality and stable images without being affected by the environment such as temperature and humidity.

Another object of the present invention is to provide a magnetic toner which makes it possible to disperse a magnetic substance, a lubricant and the like in a resin in a good manner, has excellent durability, and gives a stable image free from fog and dust even after long-term continuous use. To provide.

Another object of the present invention is to provide a magnetic toner which is always stably triboelectrically charged and maintains a high density without contaminating a triboelectric charging member such as a developing sleeve.

[Means and Actions for Solving the Problems] As a result of intensive investigations by the present inventors for the above purpose, the present inventors have determined that quaternary ammonium salts and fatty acid metal salts (metal content ratio 2.0 to 4.5% by weight, melting point 110 ° C. to 145 ° C.) are used. When used together as a charge control agent in a specific ratio, it stabilizes the positive charge of the toner, improves the dispersion of the magnetic substance and lubricant in the resin, and prevents contamination of the charge-imparting member, thus stabilizing the environment. It has been found that a toner excellent in durability and durability can be obtained.

The magnetic toner of the present invention is based on the above findings, and more specifically, the charge controllability of the quaternary ammonium salt and the fatty acid metal salt is Tc ≧ Tb ≧ Ta in terms of the triboelectric charge amount with respect to iron powder. That is, the charge controllability of the fatty acid metal salt is equal to or higher than the controllability of the quaternary ammonium salt used in combination, and the controllability when used in combination due to a synergistic effect is the same or higher than when used alone. Characterize.

When Ta> Tb, the charge amount becomes too high when used in combination at low temperature and low humidity, and uneven development density or the like tends to occur.

In the case of Tb> Tc, Ta> Tc, the effect of the combined use is not so significant, and the concentration is reduced particularly when left at high temperature and high humidity.

The charge amount of the toner of the present invention is 9.5 μc / g or more and 12.0 μc / g.
Less than g is preferred.

In the toner of the present invention, the content of quaternary ammonium salt and fatty acid metal salt in the toner is 0.4≤Wq + Wp≤2 and 0.2≤Wp / Wq≤1. It is preferred that

When Wq + Wp <0.4, the charge amount is too low, the density is low and the durability is insufficient, and poor dispersion is apt to occur, which causes fogging.

When Wq + Wp> 2, the charging member such as the developing sleeve is easily contaminated. Further, when Wp / Wq <0.2, the density is reduced under high temperature and high humidity, and when Wp / Wq> 1, the fluidity is deteriorated and an image with a lot of fog is obtained.

Further, each of Wp and Wq is preferably between 0.1 and 2.0% by weight.

Further, the metal content of the fatty acid metal salt used in the toner of the present invention is preferably 2.0% by weight to 4.5% by weight. If it is less than 2.0% by weight, the density tends to decrease under high temperature and high humidity, and the fluidity of the toner is poor. If it is 4.5% by weight or more, the combined effect with the quaternary ammonium salt is not sufficient.

Further, the melting point of the fatty acid metal salt used in the toner of the present invention is preferably 110 ° C. to 145 ° C. At 110 ° C. or less, the melt viscosity at the time of kneading the toner is too low, resulting in poor dispersion and poor fluidity, and slippage with the kneading machine causes poor dispersion of the magnetic material and lubricant, resulting in an image with a lot of fog. At 145 ° C. or higher, melting during kneading of the toner is not sufficient, and poor dispersion is likely to occur.

The fatty acid metal salt satisfying the above physical properties has 10 to 10 carbon atoms.
Good combinations of 20 fatty acids and metals such as Al and Mg are preferable, and aluminum stearate is particularly preferable.

The content of the magnetic substance in the toner of the present invention is 20 to 150 parts by weight, preferably 40 to 120 parts by weight, based on 100 parts by weight of the resin component.

The quaternary ammonium salts used in the present invention include those represented by the following general formulas (I) and (II).

In the above general formula, R ₁ , R ₂ , R ₃ and R ₄ are hydrogen, an alkyl group having 1 to 30 carbon atoms,
Aryl group or aralkyl group which may have a substituent on the aromatic ring (CH _{2 n} Ar, n = 1 to 5, Ar = aryl group)
Represents

R ₅ represents an alkyl group having 1 to 30 carbon atoms or an aralkyl group (CH _{2 n} Ar, n = 1 to 5, Ar = aryl group).

R ₆ represents an alkyl group having 1 to 10 carbon atoms, and the substituent may be plural.

 A Represents an anion.

Examples of anions include halo ions, sulfate ions, nitrate ions, borate ions, phosphate ions, organic sulfate ions,
There are organic sulfonic acid ions, organic phosphate ions, polyacid ions, heteropolyacid ions, carboxylate ions, and tetrafluoroborate.

 Specifically, there are the following.

_{(C 5 H 11) 4 N} + Br - (C 4 H 9) 4 N + I - (C 6 H 13) 4 N + No 3 - ^{_{(C 16 H 33) N +}} (CH 3) 3 Cl - (C 18 H 37) 2 N + (CH 3) 2 Br - C ₁₆ H ₃₃ N ⁺ (CH ₃ ) ₃ 1/6 [Mo ₇ O ₂₄ ] ^6- C ₁₈ H ₃₇ N ⁺ (CH ₃ ) ₃ 1/10 [H ₂ W ₁₂ O ₄₂ ] ^10- Usually, as a method for incorporating a quaternary ammonium salt and a fatty acid metal salt into a toner, there are a method in which the toner is incorporated into the toner at the time of kneading, and a method in which the salt is externally added. The effect of is not obtained. In the method of externally adding the toner to the surface of the toner later, the density is significantly reduced.

As a binder resin used in the toner of the present invention, when a heating / pressing roller fixing device having an oil applying device is used, the following binder resins for toner can be used.

For example, polystyrene, poly-p-chlorostyrene,
Homopolymers of styrene such as polyvinyltoluene and its substitution products; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene-acrylic acid ester copolymers, styrene -Methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone Styrene-based copolymers such as copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers; polyvinyl chloride, phenolic resins, natural modified phenolic resins, natural resin modified malein Acid resin, Acrylic Resins, methacrylic resins, polyvinyl acetate, silicone resins, polyester resins, polyurethane, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resin, coumarone-indene resins, and petroleum resins.

In the heat and pressure roller fixing method in which almost no oil is applied, the so-called offset phenomenon in which a part of the toner image on the toner image support member is transferred to the roller, and the adhesion of the toner to the toner image support member are important issues. is there. Toners that fix with less heat energy tend to block or cake during storage or in a developing unit, and these problems must also be considered at the same time. In these developments, the physical properties of the binder resin in the toner are most important. However, according to the study of the present inventors, when the content of the magnetic material in the toner is reduced, the toner image supporting member is not fixed during fixing. Although the adhesiveness of the toner to the toner is improved, offset tends to occur, and blocking or caking tends to occur. Therefore, in the present invention, when using the heating / pressing roller fixing method in which almost no oil is applied, the selection of the binder resin is more important. Preferred binders include crosslinked styrenic copolymers or crosslinked polyesters.

Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, and methacrylic. Acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, monocarboxylic acid having a double bond such as acrylamide or the like; for example,
Dicarboxylic acids having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and the like, and substituted products thereof; vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; Olefins such as ethylene, propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Monomers may be used alone or in combination of two or more.

Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene and the like; for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate Double bonds such as 1,3-butanediol dimethacrylate, etc.
Carboxylic acid esters having two or more compounds; 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.

When a pressure fixing method is used, a binder resin for a pressure fixing toner can be used. For example, polyethylene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer can be used. Coalescent, ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, paraffin and the like.

Further, it is preferable to add fine silica powder to the magnetic toner of the present invention. The abrasion is remarkably reduced by the presence of the silica fine powder between the toner particles and the sleeve surface in which the magnetic toner according to the present invention is combined with the silica fine powder.
As a result, the life of the magnetic toner and the sleeve can be prolonged, and a stable chargeability can be maintained, and a developer having a magnetic toner that is more excellent for long-term use can be obtained.

As the silica fine powder, both silica fine powder produced by a dry method and a wet method can be used, but from the viewpoint of filming resistance and durability, it is preferable to use a silica fine powder obtained by a dry method.

The dry method referred to here is a method for producing silica fine powder generated by vapor phase oxidation of a silicon halide.
For example, in a method utilizing the 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 Also, in this production process, for example, by using another metal halide such as aluminum chloride or titanium chloride together with a silicon halide, a fine composite powder of silica and another metal oxide is obtained. It is also possible to obtain and 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, the decomposition of sodium silicate with an acid is represented by the following general reaction formula.

Na ₂ O ・ XSiO ₂ + HCl + H ₂ O → SiO ₂・ nH ₂ O + NaCl In addition, decomposition of sodium silicate with ammonium salts or alkali salts, formation of alkaline earth metal silicate from sodium silicate, and decomposition with acid Silicate, a method of converting a sodium silicate solution into silicic acid with an ion exchange resin, and a method of using natural silicate or silicate.

Silica such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, zinc silicate, etc. can be applied to the silica fine powder here, in addition to anhydrous silicon dioxide (silica).

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. 0.01 to 8 parts by weight of silica fine powder, preferably 100 parts by weight of magnetic toner, preferably
It is preferable to use 0.1 to 5 parts by weight.

When the magnetic toner of the present invention is used, positively charged positive silica fine powder is used rather than negatively charged silica fine powder as the silica fine powder added to prevent toner abrasion and sleeve surface contamination. It is preferable to use it because it does not impair the charging stability.

As a method for obtaining a positively charged silica derivative, a method of treating the above-mentioned untreated silica fine powder with a silicone oil having an organo group having at least one nitrogen atom in a side chain, or a nitrogen-containing silane cup is used. There is a method of treating with a ring agent or a method of treating with both of them.

In the present invention, the positively-charged silica refers to a silica having a positive tribocharge with respect to the iron powder carrier when measured by a blow-off method.

As the silicon oil having a nitrogen atom in a side chain used for treating the silica fine powder, a silicon 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 and phenylene group may have an organo group having a nitrogen atom, or may be substituted with halogen or the like within a range not impairing the charging property. It may have a group.

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

R _m -Si-Y _n (R represents an alkoxy group or a halogen, Y represents an organo group having at least one amino group or a nitrogen atom, m and n is an integer of 1 to 3 m + 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 is an unsaturated heterocyclic group or 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 following.

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

Examples of such treating agents include aminopropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, Butylaminopropyltrimethoxysilane, dioctylaminopropyltrimethoxysilane, dibutylaminopropyldimethoxysilane, dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-
γ-propylphenylamine, trimethoxysilyl-γ
-Propylbenzylamine and the like, and the nitrogen-containing heterocycle may have the structure described above. Examples of such compounds include trimethoxysilyl-γ-propylpiperidine, trimethoxysilyl-γ-propylmorpholine, And trimethoxysilyl-γ-propylimidazole.

The applied amount of these treated positively charged silica fine powders is 0.01 to 8 with respect to 100 parts by weight of the positively charged magnetic toner.
The effect is exhibited when the amount is by weight, and particularly preferably 0.1 to 5 parts by weight.
Positive chargeability with excellent stability when added in parts by weight. In a preferred embodiment, the addition form is such that 0.1 to 3 parts by weight of the treated silica fine powder is attached to the surface of the toner particles based on 100 parts by weight of the positively charged magnetic toner. The untreated silica fine powder described above can be used in the same application amount.

Further, the silica fine powder used in the present invention is treated with a treating agent such as a silane coupling agent, a silicon oil, an organosilicon compound or the like in combination with various treating agents for the purpose of hydrophobicity, if necessary. It may be treated with the treating agent that reacts or physically adsorbs with the silica fine powder.
Examples of such a treating agent include hexamethyldisilazane, vinyltrimethoxysilane, vinyltriethoxysilane, trimethylsilane, trimethylchlorosilane,
Trimethylethoxysilane, dimethyldichlorosilane,
Methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α
-Chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane,
Triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane,
Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule, terminal One for each of the units located in
And a dimethylpolysiloxane having a hydroxyl group bonded thereto. The silicone oil is generally represented by the following formula.

Preferred silicone oils are those having a viscosity of about 5 to 5000 centistokes at 25 ° C., such as methyl silicone oil, dimethyl silicone oil, phenyl methyl silicone oil, chlorophenyl methyl silicone oil, alkyl-modified silicone oil, and fatty acid-modified silicone oil. Silicone oil and polyoxyalkylene-modified silicone oil are preferred. These are used alone or as a mixture of two or more.

Further, in the present invention, fine powder of a fluorine-containing polymer,
For example, it is preferable to add fine powder of polytetrafluoroethylene, polyvinylidene fluoride or the like and a tetrafluoroethylene-vinylidene fluoride copolymer. Particularly, fine powder of polyvinylidene fluoride is preferable in terms of fluidity and abrasivity. The amount added to the toner
0.01 to 2.0% by weight, particularly preferably 0.02 to 1.0% by weight.

In particular, in the magnetic toner in which the silica fine powder and the above fine powder are combined, the reason is not clear, but stabilizes the state of silica attached to the toner, for example, the attached silica is released from the toner, The effect on abrasion and sleeve fouling is not reduced, and the charging stability can be further increased.

The magnetic toner of the present invention may optionally contain additives. Other additives include, for example, cerium oxide,
Examples include abrasives such as silicon carbide, fluidity-imparting agents such as aluminum oxide, anti-caking agents, and conductivity-imparting agents such as carbon black and tin oxide.

Further, in order to improve the releasability at the time of hot roll fixing, a wax-like substance such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sasol wax, paraffin wax, etc.
The addition of about 5% by weight to the magnetic toner is also a preferred embodiment of the present invention.

Examples of the magnetic material contained in the magnetic toner of the present invention include iron oxides such as magnetite, maghemite, and ferrite, and iron oxides containing other metal oxides; metals such as Fe, Co, and Ni; and metals such as these. Al, Co, Cu, Pb, Mg, Ni, Sn, Z
Examples include alloys with metals such as n, Sb, Be, Bi, Cd, Ca, Mn, Se, Ti, W, and V, and mixtures thereof.

These ferromagnetic materials have an average particle size of about 0.1 to 2 μm,
The magnetic characteristics when 0 Ke is applied have a coercive force of 20 to 150 e
0 to 200 emu / g (preferably 50 to 100 emu / g), remanent magnetization 2
A value of ~ 20 emu / g is desirable.

In the measurement of the triboelectric charge amount in the present invention, the temperature / humidity was 23.5
The test substance is mixed with an iron powder carrier having a particle size of 200/300 mesh (Nihon Iron Powder EFV200 / 300) at a ratio of 2/98 in an environment of 60 ° C / 60%, and 0.5 to 1.5 g of this mixture is purified. Weigh 2 on metal 400 mesh screen connected to electrometer
Suction is performed with a pressure of 5 cmH ₂ O, and the amount of charge per unit weight is determined from the amount of the test substance sucked at that time and the amount of charge.

The order of the charge amount in the present invention is not changed by a conventionally known blow-off measurement method.

This order is more apparent in the black fine powder before silica addition and mixing.

The toner of the present invention can be used by any conventionally known means for one-component development for developing an electrostatic charge image in electrophotography, electrostatic recording, electrostatic printing and the like.

A particularly preferable developing method is to apply a magnetic toner uniformly on a cylindrical toner carrier having a magnet therein, to make the magnetic toner come into contact with the latent image holding member without contacting the toner, and to perform development. At this time, an AC bias may be applied between the toner carrier and the base conductor of the latent image holding member.

In the developing method as described above, the following excellent effects are exhibited.

It is a magnetic toner that gives a stable and good image regardless of temperature and humidity.

A magnetic toner that maintains a stable charging property regardless of the copy speed of the machine and gives good images from low speed machines to high speed machines.

A magnetic toner in which a magnetic material is well dispersed in a binder resin, has excellent durability, and gives an image free of fogging at all times.

It is a magnetic toner that does not stain the triboelectrification imparting member and is always stably triboelectrically charged to maintain a high concentration.

[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 After thoroughly mixing the above ingredients with a Henschel mixer, 130
C., kneaded with an extruder set at ℃, cooled, coarsely pulverized by a cutter mill, finely pulverized by a jet mill using a jet stream, classified by an air classifier, the average particle size 12
μ black fine powder was obtained. To 100 parts of the obtained black fine powder, 0.4 part of positively charged hydrophobic dry silica (BET 200 m ^{2 /} g) treated with an amino-modified silicone oil (viscosity at 25 ° C .: 100 cp, amine equivalent: 800) and an average particle size of 0.2 μm Spherical, PVdF
0.2 parts of particles were added and mixed with a Henschel mixer to obtain a magnetic toner. This magnetic toner is used in a commercial electrophotographic copying machine.
A copy test of 20,000 sheets was performed with NP-5540 (40 sheets / minute manufactured by Canon Inc.). The image density during the test is always 1.3 or more,
Fog was not observed in the background part and the reversal part, and there was little flicker. Similarly, good results were obtained in a copy test of 20,000 sheets at 15 ° C / 10% and 32.5 ° C / 85%.

Example 2 When the same procedure as in Example 1 was carried out using the above materials, 23.5
20,000 under each environment of ℃ / 60%, 32.5 ℃ / 85%, 15 ℃ / 10%
As a result of printing out one sheet, the image density was always 1.25 or more, and fog was not recognized, and there was little flicker.

Example 3 Aluminum stearate having a melting point of 140 ° C. and a metal content of 4.0
The same procedure as in Example 1 was carried out except that the amount of aluminum stearate was changed to 23.5 ° C./60%, 32.5 ° C./85% by weight.
%, 15 ℃ / 10% under the environment of 20,000 prints as a result, the image density was always 1.3 or more, fog was not observed, and there was little flicker.

Example 4 Quaternary ammonium salt Was carried out in the same manner as in Example 1 except that the temperature was changed to 23.5 ° C.
In each environment of / 60%, 32.5 ° C / 85%, and 15 ° C / 10%, 20,000 images were output. As a result, the image density was always 1.3 or more, no fog was observed, and there was little noise.

Comparative Example 1 The same procedure was performed as in Example 1 except that aluminum stearate was not used.
It is slightly lower at ~ 1.2 and may be 1.0 or less in an environment of 32.5 ° C / 85%. In an environment of 15 ° C / 10%, the concentration is 1.1.
It was ~ 1.2. Further, when image formation was performed without replenishing toner, the density was particularly lowered, and the image density was reduced to about 0.6.

Comparative Example 2 The image density was lower than that of Comparative Example 1 in the same manner as in Example 1 except that the quaternary ammonium salt was not used and the amount of aluminum stearate was 1.0 times.
Only 0.8 to 1.0, and images with a lot of fog with poor fluidity were obtained.

Comparative Example 3 The same procedure as in Example 1 was carried out except that 2 parts of nigrosine dye was used instead of the quaternary ammonium salt and aluminum stearate. The image density was 1.3 or more at the initial stage, but the density slightly decreased as the number of durable sheets increased. However, the fog was good although it was about 1.1 to 1.2. But fifteen
At ℃ / 10%, the image density was 1.35 or more in the initial stage, but there were many jumps and the density gradually decreased, and it was below 1.0, and the image became dull.

Comparative Example 4 The amount of the quaternary ammonium salt in Example 1 was 0.5 part,
When the same procedure was performed except that the amount of aluminum stearate was changed to 1.0 part, the density gradually decreased under the environment of 15 ° C / 10%, and the image became less than 1.0 and the image was rough.

Comparative Example 5 The amount of aluminum stearate in Example 1 was set to 0.
23.5 ℃ / 6 when the same method was used except that 15 parts were used.
Through the printing of 20,000 images under 0%, 15 ℃ / 10% environment
Although an image density of 1.25 or higher was obtained, it may drop below 1.20 under the environment of 32.5 ° C / 85%, especially 1.0 after standing overnight.
Down to

Comparative Example 6 The amount of the quaternary ammonium salt in Example 1 was 3.0 parts,
When the same method was used except that the amount of aluminum stearate was changed to 1.5 parts, slippage occurred at the time of kneading and the shear was not sufficiently applied. When this toner was imaged, the image density was as high as 1.40 at the beginning, but it decreased to 1.10. When the developing sleeve was cleaned with a solvent and an image was formed, the image density was restored to 1.35, and it was found that sleeve contamination had occurred.

Comparative Example 7 The same procedure as in Example 1 was repeated except that zinc stearate (melting point: 123 ° C., metal content: 10.5% by weight) was used instead of aluminum stearate.
The image was stable through the output of 000 sheets, but the image was low at 1.15 to 1.2 and slightly fogged.

Comparative Example 8 The melting point of aluminum stearate in Example 1 was 16
When the same procedure was performed except that the temperature was changed to 0 ° C and the metal content was 5.0% by weight, the dispersion of aluminum stearate was poor and the image density was as high as 1.40, but black spots and fog were generated and under the environment of 32.5 ° C / 85%. After being left overnight, the concentration decreased to 1.05.

 Table 1 shows the triboelectric charge of each toner.

[Advantages of the Invention] As described above, according to the present invention, a high-quality image can be obtained for a long period of time under any environment.

Claims (2)

(57) [Claims] 1. A magnetic toner containing a binder resin and a magnetic material as main components, wherein a quaternary ammonium salt is used as a charge control agent.
Metal content is 2.0 ~ 4.5wt% and melting point is 110 ℃ ~ 1
It contains fatty acid metal salt at 45 ℃, and each charge controllability is Tc ≧ Tb ≧ Ta A positively chargeable toner characterized in that 2. The content of quaternary ammonium salt and fatty acid metal salt in the toner is 0.4 ≦ Wq + Wp ≦ 2 and 0.2 ≦ Wp / Wq ≦ 1. The positively chargeable toner according to claim 1, wherein