JP2002365835A - Positive charge type toner and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive charge type toner ensuring good image density and fog resistance over a long period of time even when printing at a low printing rate is carried out and to provide a method for producing the toner. SOLUTION: When the positive charge type toner containing fine dry silica powder and fine wet silica powder as additives and the method for producing the toner are provided, fine dry silica powder having a positive charge type polar group and a hydrophobic group and fine wet silica powder surface-treated with a quaternary ammonium salt and having a fluorine-containing negative charge type polar group are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positively charged toner capable of obtaining good image density and fog resistance over a long period of time even when printing at a low printing rate, and a method for producing the same.

[0002]

2. Description of the Related Art In an electrophotographic developing method, a high quality image is obtained by visualizing an electrostatic latent image or visualizing the electrostatic latent image by reversal development. A toner suitable for the electrophotographic development method is obtained by mixing a thermoplastic resin as a binder, a dye as a colorant or a charge controlling agent, a wax as a pigment or a release agent, and a magnetic material, and kneading, pulverizing, and classifying. The toner particles are obtained as toner particles. Further, inorganic fine powder such as silica, titanium oxide, or alumina is added in order to impart fluidity to the toner particles or improve the cleaning property. However, these inorganic fine powders are generally rich in hydrophilicity, and the fluidity and charge rising property of the toner may be affected by the surrounding environmental conditions (humidity).

[0003] In order to prevent the influence of such environmental conditions, the surface of these inorganic fine powders is treated with a hydrophobizing agent or charged polar groups are introduced.
Specifically, in order to introduce a charged polar group, a method of subjecting a metal oxide such as silica fine powder to a surface treatment with an aminosilane coupling agent or the like and using it as an external additive of a developer is disclosed in It is disclosed in JP-A-135739 and JP-A-56-123550. According to this silane treatment method, a developer having a strong positive charge can be obtained by the terminal amino group of the aminosilane coupling agent.

Japanese Patent Application Laid-Open No. 58-216252 discloses a method in which hydrophobic silica fine particles are subjected to a surface treatment with both a positive charge controlling agent and a hydrophobicizing agent, and the resultant is used as an external additive of a developer. It is disclosed in the official gazette, a method of treating a silicic acid fine powder with a predetermined amount of a nitrogen-containing silane coupling agent and a silicone oil having a nitrogen atom and using it as an external additive of a developer, JP-A-63-73271 and JP-A-63-732
No. 72 discloses this. According to these methods, a developer exhibiting strong positive chargeability can be obtained by the action of the positive charge control agent.

Further, a method in which inorganic fine particles having both polar groups of a negatively-chargeable polar group and a positively-chargeable polar group bonded to the surface thereof is used as an external additive for a non-magnetic one-component developing toner is disclosed in, for example, -66564. According to this method, it is possible to obtain a non-magnetic one-component developing toner excellent in charge level improvement property, charge rising property, and fluidity.

Japanese Patent Application Laid-Open No. 11-160907 discloses a dry silica fine powder having a positively charged polar group and a hydrophobic group, which is used for improving the rise of charging and durability, and obtaining environmental stability. It is said that it is effective to use a wet silica fine powder which has been subjected to hydrophobic treatment with silicone oil while introducing a charged polar group. Further, JP-A-11-1
In the 43111 publication, dry silica fine powder having a positively-charged polar group and a hydrophobic group, a positively-charged polar group and a fluorine-containing polar group are used in order to improve the rise of charge rise and durability, and obtain environmental stability. It is said that it is effective to use the wet silica fine powder contained in combination.

[0007]

However, the above-mentioned prior art has the following problems (1) to (4). (1) A developer using a metal oxide treated with an aminosilane coupling agent disclosed in JP-A-52-135739 or the like can be used in a high-temperature, high-humidity environment because the aminosilane coupling agent is hydrophilic. In addition, there has been a problem that the toner fluidity and charging property become unstable. (2) A developer obtained by subjecting hydrophobic silica fine particles disclosed in JP-A-58-216252 and the like to surface treatment with both a positive charge control agent and a hydrophobizing agent has a high fluidity of toner. In addition, there were problems that the chargeability was poor, the rise of the chargeability was slow, and the chargeability was likely to be unstable. (3) Further, a developer containing inorganic fine particles having both a negatively-chargeable polar group and a positively-chargeable polar group bonded to the surface disclosed in Japanese Patent Application Laid-Open No. 2-66564 and the like can be used in a high-temperature, high-humidity environment. Under these conditions, problems such as poor charging stability and toner fluidity were observed. (4) Further, disclosed in JP-A-11-160907 and the like,
In a toner using a combination of a positively-charged dry silica fine powder and a finely-charged silica fine powder containing a positively-charged polar group and a fluorine-containing polar group, the image density and fog are reduced when the toner is used at a low printing rate. There was a problem that the stability of the composition became insufficient.

Therefore, the inventors of the present invention diligently studied these problems and used both positively-charged dry silica and wet silica fine powder in combination with wet silica fine powder.
In addition to introducing a fluorine-containing negatively charged polar group, the surface treatment with a quaternary ammonium salt stabilizes the image density over a long period of time. Did not occur, and completed the present invention.

[0009]

According to the present invention, in a positively charged toner containing fine powder of dry silica and fine powder of wet silica as an external additive, the fine powder of dry silica contains a positively charged polar group and A positively-charged toner having a hydrophobic group, wherein the wet silica fine powder has a fluorine-containing negatively-charged polar group and is surface-treated with a quaternary ammonium salt is provided. The point can be solved. That is, the addition of the finely divided dry silica having a positively charged polar group and a hydrophobic group can improve the charge rising property and reduce the change in toner fluidity due to the change in environmental conditions. it can. On the other hand, by having a fluorine-containing negatively-charged polar group and performing a surface treatment with a quaternary ammonium salt, a change with time of the positively-charged property as compared with the case of using a general amino-based silane coupling agent. And environmental fluctuations are reduced, a stable image density can be obtained, and the occurrence of fog can be prevented. The synergistic effect of these two kinds of silica fine powders makes it possible to stabilize the image density for a long time and to effectively prevent fogging even when printing with a particularly low printing ratio is performed. The quaternary ammonium salt is preferably a quaternary ammonium salt type silane compound, as described later.

In constituting the positively charged toner of the present invention, it is preferable that the positively charged polar group in the finely divided silica powder be derived from an aminosilane coupling agent.
With this configuration, it is possible to easily and quantitatively introduce a positively charged polar group into the surface of the dry silica fine powder.

In constituting the positively charged toner of the present invention, it is preferable that the hydrophobic group in the finely divided silica powder is derived from an alkylsilane coupling agent. With this configuration, it is possible to easily and quantitatively introduce a hydrophobic group into the surface of the dry silica fine powder.

In constituting the positively charged toner of the present invention, it is preferable that the fluorine-containing negatively charged polar group in the wet silica fine powder is derived from a fluorine-containing silane coupling agent. With this configuration, it is possible to easily and quantitatively introduce the fluorine-containing negatively charged polar group into the surface of the wet silica fine powder.

In constituting the positively charged toner of the present invention, a quaternary ammonium salt and a fluorine-containing powder are used with respect to 100% by weight of wet silica fine powder (synonymous with 100 parts by weight). It is preferable that the total treatment amount of the silane coupling agent and the silane coupling agent is set to a value within a range of 20 to 40% by weight. With such a configuration, a hydrophobic group can be sufficiently introduced into the wet silica fine powder, and the effect of the wet silica fine powder can be more effectively exerted. Therefore, even when printing with a low printing rate is performed, the image density is stable for a long time, and fogging can be effectively prevented.

In constituting the positively charged toner of the present invention, the weight ratio of the quaternary ammonium salt to the fluorine-containing silane coupling agent used for the surface treatment of the wet silica fine powder is in the range of 0.6 to 1.5. It is preferable to set the value within. With this configuration, the hydrophobic group can be sufficiently introduced, and the effect of the wet silica fine powder can be more effectively exerted. Therefore, even when printing with a low printing rate is performed, the image density is stable for a long time, and fogging can be effectively prevented.

Another aspect of the present invention is a method for producing a positively charged toner in which finely divided dry silica and finely divided silica are externally added, wherein the finely divided dry silica has a positively charged polar group and a hydrophobic group. A step of adding a fine powder, and a step of adding a wet silica fine powder which has a fluorine-containing negatively charged polar group and is surface-treated with a quaternary ammonium salt as a wet silica fine powder. A method for producing a positively charged toner is provided, and the above-described problems can be solved. By performing in this manner, the synergistic effect of the two types of silica fine powder stabilizes the image density for a long time, and in particular, fogging can be effectively prevented even when printing with a low printing rate is performed. The charged toner can be efficiently provided.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Referring to the drawings, embodiments of the present invention will be concretely roughly classified into magnetic toner particles (sometimes simply referred to as toner particles) and external additives. explain. It should be noted that the drawings referred to merely schematically show the sizes, shapes, and arrangements of the components so that the present invention can be understood, and therefore, the present invention is limited only to the illustrated examples. is not.

1. Magnetic Toner Particles (1) Binder Resin Type 1 The type of binder resin used for the toner particles in the present invention is not particularly limited. For example, a styrene resin, an acrylic resin, a styrene-acryl copolymer, Thermoplastic resins such as polyethylene resin, polypropylene resin, vinyl chloride resin, polyester resin, polyamide resin, polyurethane resin, polyvinyl alcohol resin, vinyl ether resin, N-vinyl resin, styrene-butadiene resin, etc. It is preferred to use.

More specifically, the polystyrene resin may be a homopolymer of styrene or a copolymer with another copolymerizable monomer copolymerizable with styrene. Examples of such copolymerized monomers include p-chlorostyrene; vinylnaphthalene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; and vinyl halides such as vinyl chloride, vinyl bromide, and vinyl fluoride. Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dotesyl acrylate, n-octyl acrylate, acrylic acid (Meth) acrylates such as 2-chloroethyl, phenyl acrylate, α-methyl methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate; and other acrylates such as acrylonitrile, methacrylonitrile, and acrylamide. Acrylic acid derivatives, vinyl methyl ether, vinyl ethers such as vinyl isobutyl ether; vinyl methyl ketone, vinyl ethyl ketone, vinyl ketones such as methyl isopropenyl ketone; N- vinyl pyrrole, N- vinyl carbazole, N- vinyl indole,
N-vinyl compounds such as N-vinylpyrrolidene are exemplified. These can be used alone and copolymerized with a styrene monomer, or two or more of them can be copolymerized with a styrene monomer.

As the polyester-based resin, any resin obtained by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component can be suitably used. Such alcohol components include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, , 5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol,
Polyethylene glycol, polypropylene glycol,
Diols such as polytetramethylene glycol; bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylene bisphenol A; sorbitol;
1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, Glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3
5, -trihydroxymethylbenzene and the like are exemplified.

As the carboxylic acid component, divalent or trivalent carboxylic acids, acid anhydrides of these carboxylic acids, or lower alkyl esters of these carboxylic acids are used. More specifically, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, or n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n
Divalent carboxylic acids such as octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid); 2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-
Examples thereof include trivalent or higher carboxylic acids such as cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empol trimer acid.

Molecular Weight Distribution The binder resin preferably has at least two or more molecular weight distribution peaks (low molecular weight peak and high molecular weight peak) in the weight average molecular weight measured by gel permeation chromatography (GPC). Specifically, the low molecular weight peak is 3,000 to
Binder resins having a molecular weight in the range of 20,000 and another high molecular weight peak in the range of 3 × 10 ⁵ to 15 × 10 ⁵ are preferred. The reason for this is that when the low molecular weight peak is within the above range, the fixability of the toner particles is improved. Conversely, when the low molecular weight peak is less than 3,000, offset tends to occur during fixing,
In addition, the storage stability of the toner particles at the use environment temperature (5 to 50 ° C.) is reduced, which may cause caking. On the other hand, when the high molecular weight peak is in the above range, the offset resistance of the toner particles is improved. Conversely, when the high molecular weight peak is larger than 20,000, the binder resin and the charge controlling agent This is because, in some cases, the compatibility with the above may be reduced and uniform dispersion may not be obtained. Therefore, fog, contamination of the photoreceptor, poor fixing and the like may easily occur.

Further, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the binder resin is preferably 10 or more. The reason for this is that if the ratio of Mw / Mn is less than 10,
This is because the molecular weight distribution becomes excessively narrow, and the fixing property and the offset resistance of the toner particles may be reduced, and both properties may not be sufficiently satisfied.

Crosslinking Structure The binder resin is preferably a thermoplastic resin from the viewpoint of good fixability, but the amount of the crosslinking component (gel amount) measured using a Soxhlet extractor is 10% by weight or less.
More preferably, if the value is within the range of 0.1 to 10% by weight, the resin may be a curable resin. By introducing a partially crosslinked structure in this way, the storage stability, shape retention, and durability of the toner particles can be further improved without lowering the fixability. Therefore, it is not necessary to use 100% by weight of a thermoplastic resin as a binder resin of the toner particles, and it is also preferable to add a crosslinking agent or to partially use a thermosetting resin.

Examples of such thermosetting resins include epoxy resins and cyanate resins, and more specifically, bisphenol A epoxy resins, hydrogenated bisphenol A epoxy resins, and novolak epoxy resins , A polyalkylene ether type epoxy resin, a cycloaliphatic type epoxy resin, a cyanate resin or the like, alone or in combination of two or more.

Functional Group It is preferable that the binder resin has a functional group (polar group) in order to improve the dispersibility of the magnetic particles. Examples of such functional groups include hydrokoxy (hydroxyl)
And at least one selected from a group, a carboxyl group, an amino group and a glycidoxy (epoxy) group. Whether or not the binder resin has these functional groups can be confirmed using an FT-IR apparatus, and the content of the functional groups can be quantified using a titration method. it can.

Glass Transition Point The glass transition point of the binder resin is preferably set to a value within the range of 55 to 70 ° C. The reason is that when the glass transition point of the binder resin is lower than 55 ° C.,
This is because the obtained toner particles tend to fuse with each other and storage stability tends to decrease. On the other hand, when the glass transition point of the binder resin exceeds 70 ° C., the fixability of the toner particles tends to be poor. Therefore,
The glass transition point of the binder resin is more preferably set to a value in the range of 58 to 68 ° C, and even more preferably to a value in the range of 60 to 66 ° C. The glass transition point of the binder resin can be determined from the point of change in specific heat using a differential scanning calorimeter (DSC).

Softening Point When the binder resin is crystalline, its melting point (or softening point) is preferably set to a value in the range of 110 to 150 ° C. The reason for this is that if the melting point (or softening point) of such a binder resin is lower than 110 ° C., the obtained toner particles may be fused to each other and storage stability may be reduced. On the other hand, if the melting point (or softening point) of the binder resin exceeds 150 ° C., the fixability of the toner particles may be significantly reduced. Therefore, the melting point (or softening point) of the binder resin is 115 to 115
It is more preferable to set the value within a range of 145 ° C.
More preferably, the value is in the range of 0 to 140 ° C. The melting point (or softening point) of the binder resin is
It can be determined from the melting peak position measured using a differential scanning calorimeter (DSC) or the falling ball method.

(2) Magnetic Particle Type The magnetic particles used in the toner particles of the present invention include iron oxide (magnetite), iron powder, cobalt powder, nickel powder, and the like.
And ferrite powder as main components, and magnetic particles obtained by doping iron oxide (magnetite) with a ferromagnetic metal such as cobalt or nickel. Further, an alloy which does not contain a ferromagnetic element as it is but becomes ferromagnetic when subjected to an appropriate heat treatment, such as chromium dioxide, can be used as the magnetic particles.

It is preferable that the magnetic particles have been subjected to a surface treatment using a surface treating agent such as a titanium-based coupling agent or a silane-based coupling agent. The reason for this is that by performing such a surface treatment, the affinity between the magnetic particles and the binder resin is improved, and the magnetic particles can be more uniformly dispersed in the binder resin. Further, since the magnetic particles are usually hydrophilic, by performing such a surface treatment, it is possible to appropriately make the particles hydrophobic, and as a result, it is possible to improve the moisture resistance of the toner particles. is there.

Average particle diameter The average particle diameter of the magnetic particles is 0.10 to 0.50 μm.
It is preferable to set the value within the range. The reason for this is that if the average particle diameter of such magnetic particles is outside these ranges, it may be difficult to uniformly disperse and uniformly charge the toner particles. Therefore, the average particle diameter of the magnetic particles is more preferably set to a value in the range of 0.15 to 0.45 μm, and even more preferably to a value in the range of 0.18 to 0.40 μm.

When the magnetic particles are applied in a one-component developing system, the amount is preferably in the range of 30 to 70% by weight based on the total amount of the toner particles. The reason for this is
If the amount of the magnetic particles is less than 30% by weight, the durability is reduced and fogging is likely to occur. On the other hand, if the added amount of the magnetic particles exceeds 70% by weight, the image density and durability may be reduced, or the fixability may be significantly reduced. Therefore, when applied to the one-component development system, it is more preferable to set the amount of the magnetic particles to a value within the range of 30 to 60% by weight. On the other hand, when applied to a two-component development system, the amount of magnetic particles to be added is preferably in the range of 5 to 30% by weight based on the total amount of toner particles. The reason for this is that if the addition amount of the magnetic particles is 5% by weight or less, durability may decrease and fog may easily occur. On the other hand, if the amount of the magnetic particles exceeds 30% by weight, the image density and durability may be reduced, or the fixing property may be significantly reduced. Therefore, when applied to the two-component development system, it is more preferable to set the amount of the magnetic particles to a value within the range of 5 to 20% by weight.

(3) Wax In the toner particles of the present invention, it is preferable to add a wax in order to obtain the effect of fixing property and offset property. Here, as the type of wax to be added,
Although not particularly limited, it is preferable to use, for example, polyethylene wax, polypropylene wax, Teflon (registered trademark) -based wax, Fischer-Tropsch wax, paraffin wax, ester wax, montan wax, rice wax, and the like. Further, these waxes may be used in combination. By adding such a wax, the offset property can be improved, and image smearing can be more efficiently prevented. The Fischer-Tropsch wax is a straight-chain hydrocarbon compound having a small number of iso-structure molecules and side chains, produced by utilizing the Fischer-Tropsch reaction, which is a catalytic hydrogenation reaction of carbon monoxide.

Further, among the Fischer-Tropsch waxes, the weight average molecular weight is a value of 1,000 or more,
Further, those having an endothermic bottom peak by DSC in the range of 100 to 120 ° C are more preferable. Examples of such a Fischer-Tropsch wax include Sasol wax C1 (high molecular weight grade obtained by crystallization of H1, endothermic bottom peak: 106.5) available from Sasol.
° C), Sasol wax C105 (refined product of C1 by a fractionation method, endothermic bottom peak: 102.1 ° C), Sasol wax SPRAY (fine particle product of C105, endothermic bottom peak: 102.1 ° C) and the like. .

The amount of the wax added is not particularly limited. For example, when the total amount of the toner particles is 100% by weight, the amount of the wax added is in the range of 1 to 5% by weight. It is preferable to set the value within. The reason for this is that if the amount of the waxes is less than 1% by weight, the offset property may be reduced, and image smearing or the like may not be effectively prevented.
On the other hand, when the added amount of the wax exceeds 5% by weight, the toners are fused to each other, and the storage stability tends to decrease.

(4) Charge Control Agent In the toner particles of the present invention, the charge level and the charge rise characteristics (indicator of whether or not the toner is charged to a constant charge level in a short time) are remarkably improved, and the toner particles are excellent in durability and stability. It is preferable to add a charge control agent, since such characteristics and the like can be obtained. Here, the type of the charge control agent to be added is not particularly limited, and examples thereof include charge control agents having the following positive chargeability and negative chargeability.

Positively Chargeable Charge Control Agent Examples of the positively chargeable charge control agent include nigrosine, a quaternary ammonium salt compound, and a resin type charge control agent in which an amine compound is bonded to a resin. Specifically, pyridazine, pyrimidine, pyrazine as azine compounds,
Orthooxazine, methoxazine, paraoxazine,
Orthothiazine, metathiazine, parathiazine, 1,
2,3-triazine, 1,2,4-triazine, 1,
3,5-triazine, 1,2,4-oxadiazine,
1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1,2,3,4-tetrazine, 1,2,4,5
-Tetrazine, 1,2,3,5-tetrazine, 1,2,
Azin Fast Red FC, Azin Fast Red 12BK, Azin Violet BO, Azin Violet 3G as direct dyes composed of 4,6-oxatriazine, 1,3,4,5-oxatriazine, phthalazine, quinazoline, quinoxaline, and azine compounds , Azin Light Brown GR, Azin Dark Green BH / C, Azin Deep Black EW and Azin Deep Black 3R
L, nigrosine as a nigrosine compound, nigrosine salt, nigrosine derivative, nigrosine BK, nigrosine NB, nigrosine Z, metal salts of naphthenic acid or higher fatty acid, alkoxylated amine, alkylamide, quaternary as acidic dyes composed of the nigrosine compound As the ammonium salt, benzylmethylhexyldecylammonium, decyltrimethylammonium chloride and the like may be used alone or in combination of two or more. In particular,
The nigrosine compound is most suitable for positively charged toner particles because a quicker rise can be obtained.

Further, a resin or oligomer having a quaternary ammonium salt, a resin or oligomer having a carboxylate, a resin or oligomer having a carboxyl group, and the like are mentioned. More specifically, a polystyrene resin having a quaternary ammonium salt, an acrylic resin having a quaternary ammonium salt, a styrene-acrylic resin having a quaternary ammonium salt, a polyester resin having a quaternary ammonium salt, carboxylic acid Polystyrene resin having a salt, acrylic resin having a carboxylate, styrene-acrylic resin having a carboxylate, polyester resin having a carboxylate, polystyrene resin having a carboxyl group, acrylic having a carboxyl group Resins, styrene-acrylic resins having a carboxyl group, polyester resins having a carboxyl group, and the like, alone or in combination of two or more.
In particular, a styrene-acrylic resin (styrene-acrylic copolymer) having a quaternary ammonium salt, a carboxylate or a carboxyl group as a functional group can easily adjust the charge amount to a value within a desired range. It is the best charge control agent because it can.

Negatively-chargeable charge control agents As those exhibiting negatively-chargeable properties, for example, organometallic complexes and chelate compounds are effective, and monoazo metal complexes,
There are acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids and aromatic polycarboxylic acids and metal salts thereof, anhydrides and esters thereof, and phenol derivatives such as bisphenol.

Addition amount When the total amount of the toner particles is 100% by weight, it is preferable that the addition amount of the charge control agent is in a range of 1.5 to 15% by weight. The reason for this is that if the amount of the charge control agent is less than 1.5% by weight, it becomes difficult to stably impart charging characteristics to the toner particles, resulting in a low image density and low durability. This is because they tend to decrease. In addition, dispersion failure is likely to occur, which may cause so-called fogging, or may cause severe photoconductor contamination. On the other hand, if the added amount of the charge control agent exceeds 15% by weight, environmental resistance, in particular, poor charging under high temperature and high humidity, poor image quality, and defects such as photoconductor contamination tend to occur easily. . Therefore, since the balance between the charge control function and the durability of the toner particles and the like becomes better, the addition amount of the charge control agent is set to a value within the range of 2.0 to 8.0% by weight. More preferably, the value is more preferably in the range of 3.0 to 7.0% by weight.

(5) Property Improving Agent For the purpose of improving the fluidity and storage stability of the toner particles, colloidal silica or hydrophobic silica as a property improving agent is added, or these colloidal silicas are used. In addition, it is preferable to perform a surface treatment on the toner particles.

(6) Average Particle Size The average particle size of the toner particles is not particularly limited, but is preferably, for example, a value within the range of 5 to 12 μm. The reason for this is that if the average particle size of the toner particles is less than 5 μm, the storage stability may be easily reduced. On the other hand, if the average particle size of the toner particles is larger than 12 μm, the transportability may be reduced, or the fixed image may be unclear. Therefore, the average particle size of the toner particles is 6
More preferably, the value is in the range of 11 μm.

2. External treatment agent In the toner particles of the present invention, the charge amount distribution is uniform, showing stable charging characteristics without lowering the triboelectric charge amount and without charging up, and having fluidity, environmental dependency, and durability. In order to provide an excellent developer, it is necessary to externally add both specific dry silica fine powder and wet silica fine powder to toner particles.

(1) Dry Silica Fine Powder Surface Treatment Agent In order to introduce a positively charged polar group into a dry silica fine powder (fumed silica) produced by a dry method, a positively charged polar group must be used as a surface treatment agent. It is preferable to use a coupling agent. Examples of such a coupling agent having a positively charged polar group include an aminosilane coupling agent, for example, an aminosilane coupling agent represented by the following formula and a mixture thereof.

H ₂ N (CH ₂ ) ₂ NH (CH ₂ ) ₃ Si (OCH ₃ ) ₃ H ₂ N (CH ₂ ) ₂ NH (CH ₂ ) ₃ Si (CH ₃ ) (OCH
_{3) 2 H 2 N (CH} 2) 2 NH (CH 2) 2 Si (OCH 3) 3 H 2 N (CH 2) 2 NH (CH 2) 2 NH (CH 2) 2 Si
_{(OCH 3) 3 H 2 N} (CH 2) Si (OCH 3) 3 C 6 H 5 NH (CH 2) 3 Si (OCH 3) 3

In order to introduce a hydrophobic group into dry silica fine powder (fumed silica), it is preferable to use an alkylsilane coupling agent as a surface treatment agent.
Such an alkylsilane coupling agent (hydrophobizing agent)
For example, it is preferable to use a silane coupling agent represented by the following formula.

CH ₃ Si (OCH ₃ ) ₃ CH ₃ Si (OCH ₂ CH ₅ ) ₃ (CH ₃ ) ₂ Si (OCH ₃ ) ₂ CH ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ CH ₃ (CH _{2 ) 5 Si (OCH 3) 3} n-C 10 H 21 Si (OCH 3) 3 C 6 H 5 Si (OCH 3) 3

There are various methods for treating the surface of the dry silica fine powder using a coupling agent. For example, the following method is preferable. i) coupling agent is tetrahydrofuran, toluene,
Mix and dilute with a solvent such as ethyl acetate, methyl ethyl ketone and acetone. Next, the diluted solution of the obtained coupling agent is added dropwise or sprayed to the finely divided dry silica powder which is forcibly stirred by a blender or the like, and mixed well. The resulting mixture is then:
Heat in oven and dry. Thereafter, the mixture is again stirred with a blender and sufficiently crushed. ii) The dry silica fine powder is immersed in an organic solvent solution containing a coupling agent and then dried, or the dry silica fine powder is dispersed in water to form a slurry, and an aqueous solution of the coupling agent is dropped. I do. Thereafter, the dry silica fine powder is settled, dried by heating, and further crushed.

The amount of the positively charged polar group introduced to the surface of the dry silica fine powder, that is, the amount of the coupling agent having a positively charged polar group (aminosilane coupling agent) is adjusted to 100% by weight of the dry silica fine powder. Is preferably in the range of 5 to 25% by weight. The reason is that when the amount of the coupling agent having the positively charged polar group is less than 5% by weight, the introduction of the positively charged polar group becomes insufficient,
This is because the effect of adding the fine silica powder may be reduced. On the other hand, when the amount of the coupling agent having the positively charged polar group exceeds 25% by weight, the introduction of the positively charged polar group increases, and accordingly, the decrease in hydrophobicity due to the amino group increases, This is because environmental fluctuations may increase. Therefore, the addition amount of the coupling agent having a positively charged polar group is more preferably in the range of 7 to 23% by weight, and more preferably 10 to 20% by weight, based on 100% by weight of the dry silica fine powder. It is more preferable to set the value within the range.

The amount of the hydrophobic group introduced to the surface of the dry silica fine powder, that is, the amount of the coupling agent (alkylsilane coupling agent) having a hydrophobic group, is determined based on 100% by weight of the dry silica fine powder. 10-30% by weight
It is preferable to set the value within the range. The reason is that when the amount of the coupling agent having the hydrophobic group is less than 10% by weight, the introduction of the hydrophobic group becomes insufficient,
This is because the effect of adding the fine silica powder may be reduced. On the other hand, when the amount of the coupling agent having the hydrophobic group exceeds 30% by weight, the introduction of the hydrophobic group increases, and the positive chargeability is inhibited, and a predetermined positive chargeability is obtained. This is because it may disappear. Therefore,
More preferably, the amount of the coupling agent having a hydrophobic group is set to a value within the range of 12 to 27% by weight with respect to 100% by weight of the dry silica fine powder.
It is more preferred that the value be in the range of weight%.

Addition amount The addition amount of the dry silica fine powder having a positively charged polar group and a hydrophobic group is set to 0.3 to 100% by weight of the toner particles.
It is preferable to set the value in the range of ３3% by weight. The reason for this is that when the amount of the dry silica fine powder is less than 0.3% by weight, the effect of adding the dry silica fine powder may be reduced. On the other hand, when the addition amount of the fine silica powder exceeds 3% by weight, the fluidity is improved, but the fluctuation of the external additive is increased due to excessive addition, and the stability of the image density is deteriorated. This is because the occurrence of fog may increase. On the other hand, if the added amount of the fine silica powder exceeds 3% by weight, the preservability is improved, but the fixability is sometimes deteriorated.
Therefore, it is more preferable that the amount of the fine silica powder is in the range of 0.4 to 2% by weight, and more preferably in the range of 0.5 to 1% by weight, based on 100% by weight of the toner particles. More preferably, it is set to a value.

Average Particle Size The dry silica fine powder having a positively charged polar group and a hydrophobic group preferably has an average particle size within a range of 10 to less than 100 nm. The reason for this is that if the average particle size of the dry silica fine powder is 100 nm or more, there is a risk of damaging the photoreceptor, and it may be difficult to disperse and mix with the magnetic toner particles. It is. However, if the average particle size of the dry silica fine powder is excessively small, for example, if the average particle size is less than 10 nm, the phenomenon of burying in the surface of the toner particles proceeds, and the static silica excellent in fluidity, environment dependency, and durability is excellent. In some cases, it may be difficult to provide a toner for developing an electrostatic latent image. Therefore, the average particle diameter of the fine silica powder is more preferably set to a value in the range of 15 to 90 nm, and further preferably to a value in the range of 20 to 80 nm.

(2) Surface treatment agent for wet silica fine powder In order to introduce a fluorine-containing negatively charged polar group into the wet silica fine powder, a fluorine-containing silane coupling agent as a surface treatment agent, for example, represented by the following formula: It is preferred to use the compounds and mixtures thereof. _{CF 3 (CH 2) 2 Si} (OCH 3) 3 CF 3 (CF 2) 7 (CH 2) 2 Si (OCH 3) 3 CF 3 (CH 2) 2 Si (CH 3) (OCH 3) 2 CF 3 _{(CF 2) 3 (CH 2} ) 2 Si (OCH 3) 3 CF 3 (CF 2) 4 (CH 2) 3 Si (OCH 3) 3 CF 3 (CF 2) 2 (CH 2) 6 Si (OCH 3 ) ₃ CF ₃ (CF ₂ ) ₆ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (CH ₃ ) (OCH ₃ ) ₂

The quaternary ammonium salt as the surface treating agent includes, for example, quaternary ammonium salt type silane compounds represented by any of the following formulas (1) to (4). _{[(R 1 O) 3 Si} (CH 2) n NR 2 R 3] + X - (1) [(R 1 O) 2 R 1 Si (CH 2) n NR 2 R 3] + X - (2) _{[(R 1 O) (R} 1) 2 Si (CH 2) n NR 2 R 3] + X - (3) [(R 1) 3 Si (CH 2) n NR 2 R 3] + X - (4 Wherein R _{1 to} R ₃ in the formulas (1) to (4) are each independently an alkyl group having 1 to 20 carbon atoms and an aromatic group; An integer of 10;
X ^- is a counter ion. ]

The amount of the fluorine-containing negatively charged polar group introduced into the surface of the wet silica fine powder, that is, the amount of the fluorine-containing silane coupling agent to be added is 10 to 30 with respect to 100% by weight of the wet silica fine powder. It is preferable to set the value in the range of% by weight. The reason for this is that if the amount of the fluorine-containing silane coupling agent is less than 10% by weight, the introduction of hydrophobic groups becomes insufficient, and the effect of adding the wet silica fine powder may be reduced. . On the other hand, when the amount of the fluorine-containing silane coupling agent exceeds 30% by weight, the introduction of the hydrophobic group increases, the effect of adding the positively charged polar group is weakened, and the positively charged property is inhibited. Because there is. Therefore, the amount of the fluorine-containing silane coupling agent to be added is more preferably in the range of 12 to 27% by weight, and more preferably in the range of 15 to 25% by weight, based on 100% by weight of the wet silica fine powder. Is more preferable.

Further, the treatment amount (addition amount) of the quaternary ammonium salt is 5% with respect to 100% by weight of the wet silica fine powder.
It is preferable to set the value in the range of 〜20% by weight. The reason for this is that if the amount of the quaternary ammonium salt is less than 5% by weight, the effect of adding the wet silica fine powder may be reduced. On the other hand, when the amount of the quaternary ammonium salt exceeds 20% by weight,
This is because the effect of the fluorine-containing negatively charged polar group may be suppressed. Therefore, the addition amount of the quaternary ammonium salt is more preferably set to a value within the range of 8 to 18% by weight, and more preferably within the range of 10 to 15% by weight, based on 100% by weight of the wet silica fine powder. It is more preferable to set the value.

Further, the total processing amount of the fluorine-containing silane coupling agent and the quaternary ammonium salt with respect to 100% by weight of the wet silica fine powder is set to a value within the range of 20 to 40% by weight. Is preferred. The reason for this is that if the total treatment amount of such a surface treatment agent is less than 20% by weight, the image density under high-temperature and high-humidity conditions may decrease, or fog may easily occur. On the other hand, if the total amount of the surface treatment agent exceeds 40% by weight, the image density may be reduced under high-temperature and high-humidity conditions or when driven for a long time,
This is because fog may easily occur. Therefore, the total treatment amount of the surface treating agent is more preferably set to a value within the range of 23 to 38% by weight, and more preferably to a value within the range of 25 to 35% by weight, based on 100% by weight of the wet silica fine powder. Is more preferable.

Weight Ratio When the wet silica fine powder is treated, the weight ratio of the quaternary ammonium salt to the fluorine-containing silane coupling agent is preferably set to a value within the range of 0.6 to 1.5. . The reason for this is that when the weight ratio is less than 0.6, the chargeability decreases, and accordingly, the image density decreases,
This is because fog may easily occur. On the other hand, if the weight ratio exceeds 1.5, the chargeability is increased, and the image density during durability may be reduced. Therefore, the weight ratio of the quaternary ammonium salt to the fluorine-containing silane coupling agent is more preferably set to a value within the range of 0.8 to 1.2, and more preferably 1.0 to 1.2.
It is more preferable to set the value within the range.

Next, referring to FIGS. 2A and 2B, the amount of the quaternary ammonium salt and the fluorine-containing silane coupling agent when the wet silica fine powder is treated. Is specifically described. In FIG. 2 (A), the horizontal axis shows the amount of quaternary ammonium salt treated (% by weight) with respect to 100% by weight of wet silica fine powder, and the vertical axis shows 100% by weight of wet silica fine powder. , The processing amount (% by weight) of the fluorine-containing silane coupling agent is shown. Then, a region surrounded by ABCDEF (shaded portion)
However, based on the evaluation criteria shown in Example 1, the quaternary ammonium salt and the fluorine-containing silane obtained at an image density of 1.3 or more and have no or little fog. It shows the throughput of the coupling agent. That is, when it is desired to obtain excellent image density and fog resistance, a quaternary ammonium salt and a quaternary ammonium salt are used when processing the wet-type silica fine powder so as to be positioned inside the shaded portion shown in FIG. It will be preferable to determine the throughput of the fluorine-containing silane coupling agent.

Also in FIG. 2B, the horizontal axis shows the processing amount (% by weight) of the quaternary ammonium salt with respect to 100% by weight of the wet silica fine powder, and the vertical axis shows the wet type. The processing amount (% by weight) of the fluorine-containing silane coupling agent with respect to 100% by weight of the silica fine powder is shown. The area (shaded area) surrounded by ABCD is an area where the weight ratio of the quaternary ammonium salt / the fluorine-containing silane coupling agent satisfies the condition of 0.6 to 1.5, and the obtained image is obtained. The graph shows the processing amount of the quaternary ammonium salt and the fluorine-containing silane coupling agent in a region where the concentration value is further improved and fog does not occur at all. That is, when it is desired to obtain better image density and fog resistance, the quaternary ammonium salt when processing the wet silica fine powder is positioned inside the hatched portion shown in FIG. 2 (B). It is understood that it is preferable to determine the treatment amount of the fluorine-containing silane coupling agent and the treatment amount of the fluorine-containing silane coupling agent, respectively.

Addition amount The addition amount of the wet silica fine powder having a fluorine-containing negatively charged polar group and surface-treated with a quaternary ammonium salt is set to 0.2 to 100% by weight of the toner particles. It is preferable to set the value in the range of 3% by weight. The reason for this is that if the addition amount of the wet silica fine powder is less than 0.2% by weight, the effect of suppressing charge-up as a toner may be lost. On the other hand, if the addition amount of the wet silica fine powder exceeds 3% by weight, the charge amount of the toner may decrease, and a sufficient image density may not be obtained. Therefore, the addition amount of the wet silica fine powder is set to 100% by weight of the toner particles.
Is preferably in the range of 0.3 to 2% by weight, and more preferably in the range of 0.5 to 1% by weight.

Average Particle Size The average particle size of the wet silica fine powder having a fluorine-containing negatively charged polar group and surface-treated with a quaternary ammonium salt is set to a value within the range of 200 to less than 500 nm. Is preferred. The reason for this is that if the average particle size of the wet silica fine powder is 500 nm or more, uniform charging characteristics may be exhibited, or dispersion and mixing with the toner particles may be difficult. . On the other hand, if the average particle size of the wet silica fine powder is less than 200 nm, uniform charging characteristics may be exhibited, and aggregation may be easily caused. Therefore, the average particle diameter of the wet silica fine powder is more preferably set to a value in the range of 250 to 450 nm, and further preferably to a value in the range of 280 to 400 nm.

(3) Addition Ratio The addition ratio of the dry silica fine powder and the wet silica fine powder is preferably set to a value within the range of 10:90 to 90:10 by weight. The reason for this is that if the addition ratio of the fine silica powder is less than 10%, the polishing is insufficient, and image flow occurs at high temperature and high humidity, which may result in image defects. On the other hand, when the addition ratio of the fine silica powder is 90% or more, the charge amount of the toner particles exceeds an appropriate value, causing charge-up, and the charge amount distribution becomes broad, and as a result, the image density is reduced. This is because there is a case where the durability or the durability is deteriorated. Therefore, the addition ratio of the dry silica fine powder and the wet silica fine powder is 20:80 to 80:20 by weight ratio.
Is preferably within a range of 30:70 to 7
More preferably, the value is in the range of 0:30.

(4) Addition Amount The total addition amount of the dry silica fine powder and the wet silica fine powder is set to a value within the range of 0.5 to 5% by weight based on 100% by weight of the magnetic toner particles. Is preferred. The reason for this is that if the total addition amount is less than 0.5% by weight, the polishing effect on the photoreceptor becomes insufficient, or image flow occurs at high temperature and high humidity, resulting in image defects. Because there is. On the other hand, when the total amount is 5% by weight or more, the fluidity of the toner is extremely deteriorated, so that the image density and durability may decrease. Therefore, the total added amount of the dry silica fine powder and the wet silica fine powder is determined by the magnetic toner particles 10.
With respect to 0% by weight, the value is more preferably in the range of 0.6 to 4.5% by weight, and even more preferably in the range of 0.7 to 4.3% by weight.

3. 1. Image Forming Apparatus (1) Configuration FIG. 1 shows an example of an image forming apparatus to which the toner of the present invention is applied. The image forming apparatus 1 includes a positively-charged photosensitive drum (photosensitive member) 9 rotating clockwise in FIG.
A developing unit 10, a transfer roller 19, a cleaning blade 13, and a charging unit 8 are provided along the rotation direction. A developing roller 32 is provided in the developing device 10, and the surface of the developing roller 32 is separated from the surface of the photoconductor 9 by a predetermined distance. Thus, a predetermined amount of toner can be supplied as needed.

An optical transmission mechanism 5 for forming image dots on the surface of the photoconductor 9 is provided above the photoconductor 9. The optical transmission mechanism 5 is not shown, but the polygon mirror 2 for reflecting the laser light from the laser light source and the laser light are applied to the surface of the photoconductor between the charging unit 8 and the developing roller 32 via the reflection mirror 4. And an optical system 3 for forming image dots. In addition, a base 54 that houses a control circuit 71 for controlling the apparatus described below is provided below the image forming apparatus 1, and a recording paper container 55 is provided above the base 54 from outside. It is arranged detachably. The recording paper container 55 is provided with a storage 14 for storing recording paper before transfer. Then, the recording paper placed on the pressing spring 52 is transported by the transport rollers 53 and 15 through the passages 16 and 17 to the registration roller 18 provided facing the auxiliary roller 30. Have been.

On the right side of the image forming apparatus 1, a front door 50 is disposed so as to be openable and closable as shown by a virtual line 50 '. When the front door 50 opens and closes as shown by a virtual line 50',
The recording paper placed on the imaginary line 50 ′ of the front door is configured to be transported to the passage 17 by the transport roller 51. On the left side of the image forming apparatus 1, a fixing unit is configured by fixing rollers 23 and 24, and the recording paper that has passed between the photoconductor 9 and the transfer roller 19 is fixed by these fixing rollers 23 and 24. Further, the recording paper after the fixing is configured to pass through the passage 27 by the conveying rollers 25 and 26, and is further accumulated in the transferred recording paper accumulation bin 6 by the rollers 28 and 29. Furthermore, a display unit 4 for displaying various information is provided on the upper part of the image recording apparatus 1.
7, an installation switch 48 and a power switch 49 are provided.

(2) Operation In the image recording apparatus 1 configured as described above, the main motor (not shown) starts driving by opening and closing the power switch 49, and the photosensitive member is operated by the start switch (not shown). The optical transmission mechanism 5 is configured to be able to form an image on the surface of the photoconductor 9 by rotating the clockwise direction 9. And the formed image is
The toner is developed by the developing roller 32 of the developing device 10,
The toner-developed image is transferred to recording paper by a transfer roller 19. The recording paper on which the toner is further transferred is
The image is fixed and fixed by the fixing rollers 23 and 24, and is conveyed to the accumulation storage 6 by the rollers 25, 27, 28 and 29 to be accumulated. Note that the developing roller 32
Undeveloped toner is supplied to the cleaning blade 13
Will be collected.

[0068]

Hereinafter, the present invention will be described in more detail with reference to examples. However, since silica for external addition was manufactured prior to the examples, it will be described first. Needless to say, the following description is an exemplification of the present invention, and the scope of the present invention is not limited to the following description without any particular reason.

[Production of externally added silica] Externally added silica A
1 was prepared as follows. Next, the blow-off charge amount and the degree of hydrophobicity of the manufactured silica for external addition were measured. Table 3 shows the obtained results. The amount of blow-off charge was determined by subjecting 5 parts by weight of the obtained silica for external addition and 100 parts by weight of the ferrite carrier to a normal environment (20 ° C., 6 ° C.).
(5% RH), and frictionally charged for 60 minutes, and then measured using a blow-off powder charge amount measuring device (manufactured by Toshiba Chemical Corporation). The hydrophobicity of the silica for external addition is 0.1.
1 g of silica for external addition was added to 50 ml of water, and methanol was added to water with stirring at a rate of 2 ml / min. As a methanol concentration when the silica for external addition started precipitation,
It was measured.

(1) Production of Silica A In a vessel, 15 g of H ₂ N (CH ₂ ) ₂ NH (CH ₂ ) ₃ S
i (OCH ₃ ) ₃ and 15 g of (CH ₃ ) ₂ Si (OC
H ₃ ) ₂ was dissolved in 30 g of toluene to prepare a diluted solution. Next, while stirring 100 g of fumed silica (Aerosil # 130; manufactured by Nippon Aerosil Co., Ltd.), the resulting diluted solution was gradually added dropwise, and further stirred vigorously for 10 minutes to form a mixture. Then, mix 1
The mixture was heated in a high-temperature bath at 50 ° C. and further crushed to obtain silica A. (2) Production of silica B In a vessel, 15 g of H ₂ N (CH ₂ ) ₂ NH (CH ₂ ) ₃ S
i (CH ₃ ) (OCH ₃ ) ₂ and 15 g of CH ₃ (CH ₂ ) ₅
Si (OCH ₃ ) ₃ was dissolved in 30 g of toluene to prepare a diluted solution. Next, while stirring 100 g of fumed silica (Aerosil # 130; manufactured by Nippon Aerosil Co., Ltd.), the resulting diluted solution was gradually added dropwise, and further stirred vigorously for 10 minutes to form a mixture. Thereafter, the mixture was heated in a high-temperature bath at 150 ° C., and further crushed to obtain silica B.

(3) Production of Silica a After dissolving 20 g of a quaternary ammonium salt type silane in 100 ml of toluene in a container, colloidal silica (N
100 g of ipsilE-200 (manufactured by Nippon Silica Co., Ltd.) was further immersed to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica a.

(4) Production of Silica b CF ₃ (CH ₂ ) ₂ S was added to 100 ml of toluene in a container.
After dissolving 20 g of i (OCH ₃ ) ₃ , 100 g of colloidal silica (NipsilE-200; manufactured by Nippon Silica Co.) was further immersed to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica b.

(5) Production of silica c 10 g of quaternary ammonium salt type silane and CF ₃ (CH ₂ ) ₂ Si (OC
After dissolving 5 g of H ₃ ) ₃ , colloidal silica (NipsilE)
(-200; manufactured by Nippon Silica Co., Ltd.) was further immersed to prepare a mixed solution. After thoroughly stirring this mixed solution,
The resultant was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica c.

(6) Production of silica d 15 g of quaternary ammonium salt type silane and CF ₃ (CH ₂ ) ₂ Si (OC
After dissolving 5 g of H ₃ ) ₃ , colloidal silica (NipsilE)
(-200; manufactured by Nippon Silica Co., Ltd.) was further immersed to prepare a mixed solution. After thoroughly stirring this mixed solution,
After heating and drying at 120 ° C., the mixture was further crushed using a pin mill to obtain silica d.

(7) Production of silica e 15 g of quaternary ammonium salt type silane and CF ₃ (CH ₂ ) ₂ Si (OC) were placed in 100 ml of toluene in a container.
After dissolving 10 g of H ₃ ) ₃ , colloidal silica (Nipsi
lE-200; manufactured by Nippon Silica Co., Ltd.) was further immersed in 100 g to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica e.

(8) Production of silica f In 100 ml of toluene in a container, 10 g of a quaternary ammonium salt type silane and CF ₃ (CH ₂ ) ₂ Si (OC)
After dissolving 15 g of H ₃ ) ₃ , colloidal silica (Nipsi
lE-200; manufactured by Nippon Silica Co., Ltd.) was further immersed in 100 g to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica f.

(9) Production of silica g 10 g of quaternary ammonium salt type silane and CF ₃ (CH ₂ ) ₂ Si (OC) were placed in 100 ml of toluene in a container.
After dissolving 25 g of H ₃ ) ₃ , colloidal silica (Nipsi
lE-200; manufactured by Nippon Silica Co., Ltd.) was further immersed in 100 g to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica g.

(10) Production of silica h 20 g of quaternary ammonium salt type silane and CF ₃ (CH ₂ ) ₂ Si (OC
After dissolving 15 g of H ₃ ) ₃ , colloidal silica (Nipsi
lE-200; manufactured by Nippon Silica Co., Ltd.) was further immersed in 100 g to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica h.

(11) Production of Silica i In 100 ml of toluene in a container, 20 g of a quaternary ammonium salt type silane and CF ₃ (CH ₂ ) ₂ Si (OC)
After the H _{3) 3} was 20g dissolved, colloidal silica (Nipsi
lE-200; manufactured by Nippon Silica Co., Ltd.) was further immersed in 100 g to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica i.

(12) Production of Silica j In 100 ml of toluene in a container, 20 g of a quaternary ammonium salt type silane and CF ₃ (CH ₂ ) ₂ Si (OC)
After dissolving 25 g of H ₃ ) ₃ , colloidal silica (Nipsi
lE-200; manufactured by Nippon Silica Co., Ltd.) was further immersed in 100 g to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica j.

(13) Production of silica k H ₂ N (CH ₂ ) ₂ N was added to 100 ml of toluene in a container.
15 g of H (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and CF ₃ (C
After dissolving 15 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ , respectively, colloidal silica (NipsilE-200; manufactured by Nippon Silica Co., Ltd.)
100 g was further immersed to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica k.

(14) Production of silica 1 H ₂ N (CH ₂ ) ₂ N was placed in 100 ml of toluene in a container.
15 g of H (CH ₂ ) ₃ Si (CH ₃ ) (OCH ₃ ) ₂
After 15 g of F ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ was dissolved, 100 g of colloidal silica (NipsilE-200; manufactured by Nippon Silica Co.) was further immersed to prepare a mixed solution. After sufficiently stirring this mixed solution, the mixture was heated and dried at 120 ° C., and further crushed using a pin mill to obtain silica 1.

Example 1 (1) Production of Toner Particles A styrene / acrylic resin, a magnetic powder, a charge controlling agent, and a wax were melted by a twin-screw extruder so as to have the following composition. Kneaded. After cooling, pulverization and classification were performed to obtain toner particles having an average particle diameter of 8 μm. Also, the particle size distribution of the obtained toner particles was measured, and 5 to 13
It was confirmed that 80% by weight or more of the whole was distributed within the range of the particle diameter of μm. Styrene / acrylic resin 100% by weight Magnetic powder (BL-200; manufactured by Titanium Co., Ltd.) 75% by weight Charge control agent (TP-415; Hodogaya Chemical Co., Ltd.) 4% by weight Wax (Viscol TS-200; Sanyo) 4% by weight of Kasei Kogyo Co., Ltd.)

(2) Evaluation of Positively Charged Toner The above silica A (shown as silica 1 in the table) was 0.4% by weight based on the obtained toner particles, and the above silica a (in the table) was used. , Silica 2) is 0.4.
% By weight to form a positively charged toner (magnetic two-component developer). Then, using a Kyocera page printer (FS-3750), the image characteristics and image deletion of the positively charged toner were evaluated. Note that a 2% printed original was used as the printing durability printing pattern.

Image Characteristics Using the obtained positively-charged toner, actual printing of 200,000 sheets was performed using a Kyocera page printer (FS-3750). Based on the following criteria, initial image characteristics, image characteristics after printing, and high temperature Evaluation of image characteristics under wet conditions was performed. That is, the normal environment
At (20 ° C., 65% RH), an image evaluation pattern is printed as an initial image, and the solid image density as the image evaluation pattern is
It was measured using a Macbeth reflection densitometer. Also, normal environment
(20 ° C., 65% RH), image characteristics after printing 200,000 sheets were similarly measured and evaluated. In addition, high temperature and high humidity conditions (33 ° C, 85% R
In H), an image evaluation pattern was printed, and image characteristics were measured and evaluated in the same manner. A: Image density is a value of 1.35 or more. ：: Image density is a value of 1.3 or more and less than 1.35. Δ: Image density is a value of 1.2 or more and less than 1.3. X: The image density is a value less than 1.2.

Using the obtained positively charged toner, as in the evaluation of image characteristics, actual printing of 200,000 sheets was performed using a Kyocera page printer (FS-3750). The fogging property after that and the fog property under the high temperature and high humidity conditions (ground fog) were evaluated. ：: No fog occurred. Δ: Some fogging has occurred. X: Remarkable fog is generated.

[Examples 2 to 8] The same toner particles as those in Example 1 were prepared, and the above-mentioned silicas A and B and silicas e to i were mixed with the toner particles as shown in Table 1. Combine and add with changing the processing amount and weight ratio,
A positively charged toner (magnetic two-component developer) was prepared and evaluated. Table 1 shows the obtained results. As is clear from the results, the quaternary ammonium salt was treated with both the quaternary ammonium salt type silane and the fluorine-containing silane coupling agent, and the total treatment amount was in the range of 20 to 40% by weight. By setting the weight ratio of the silane / fluorine-containing silane coupling agent to 0.6 to 1.5, good image density and fog resistance can be maintained even when printing at a low printing rate is performed. Can be obtained over a period of time.

[Comparative Examples 1 to 6] The same toner particles as in Example 1 were prepared, and as shown in Table 1, the above silicas A and B were added alone to the toner particles, or Positively charged toner (magnetic two-component developer) was prepared by adding in combination with silica j to m and evaluated. Table 1 shows the obtained results. As a result, in Comparative Examples 1 and 2, it is difficult to stabilize the charging characteristics for a long period of time because no specific wet silica fine powder is used in combination. Was found to be difficult. In Comparative Examples 3 to 5,
Whether the wet silica fine powder does not have a fluorine-containing negatively charged polar group or is not subjected to a surface treatment with a quaternary ammonium salt, so that it is difficult to stabilize the charging characteristics for a long period of time. Or, it was confirmed that it was difficult to use it under high temperature and high humidity conditions.

[Examples 9 to 13] The same toner particles as those of Example 1 were prepared, and the above-mentioned silicas A and B and silicas c to i were mixed with the toner particles as shown in Table 1. Along with the combination, the processing amount and the weight ratio were changed, and a positively charged toner (magnetic two-component developer) was prepared and evaluated. Table 2 shows the obtained results.

As can be seen from the results, in Example 9, the wet silica fine powder (silica) had a total treatment amount of the quaternary ammonium salt and the fluorine-containing silane of 15% by weight with respect to the silica fine powder. Probably because c) was used, it was confirmed that the image density was low under high-temperature and high-humidity conditions, and that fog also occurred under high-temperature and high-humidity conditions. In Examples 10 and 12, the total amount of the quaternary ammonium salt and the fluorine-containing silane was 20% with respect to the silica fine powder.
This is probably due to the use of the wet silica fine powder (silica d), which was relatively small in weight%, but the image density was still low under high-temperature and high-humidity conditions, and fog was also observed under high-temperature and high-humidity conditions. In Examples 11 and 13, the wet silica fine powder (silica j) was used in which the total processing amount of the quaternary ammonium salt and the fluorine-containing silane was relatively large at 45% by weight with respect to the silica fine powder. It seems that the image density under a high temperature and high humidity condition was slightly low, and it was confirmed that fogging was slightly generated.

[0091]

[Table 1]

[0092]

[Table 2]

[0093]

[Table 3]

[0094]

As is apparent from the above description, according to the present invention, a dry silica fine powder subjected to a specific surface treatment and a wet silica fine powder are used in combination as an external additive for toner particles. By doing so, it is possible to provide a positively charged toner capable of obtaining good image density and fog resistance over a long period of time even when printing with a low printing rate is performed. In particular, in the positively charged toner of the present invention, the total processing amount of the quaternary ammonium salt and the fluorine-containing silane coupling agent is in the range of 20 to 40% by weight, and the quaternary ammonium salt / fluorine-containing silane coupling is used. By setting the weight ratio of the agent to 0.6 to 1.5, even when printing at a low printing rate, it is possible to reliably obtain good image density and fog resistance over a long period of time. became.

Further, according to the method for producing a positively charged toner of the present invention, even when printing at a low printing rate is performed,
It has become possible to efficiently provide a positively charged toner capable of obtaining good image density and fog resistance over a long period of time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an image forming apparatus to which the toner of the present invention is applied.

FIG. 2 is a diagram showing a correlation between the treatment amount of a quaternary ammonium salt and a fluorine-containing silane coupling agent with respect to wet silica fine powder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Polygon mirror 5 Optical transmission mechanism 7 Top door 9 Photoconductor 10 Developing device 31 Toner container 32 Developing roller 33 Supply roller 39 Toner sensor 47 Display part

Claims (7)

[Claims] 1. A positively charged toner containing fine silica powder and fine silica powder as an external additive, wherein the fine silica powder has a positively charged polar group and a hydrophobic group. A positively charged toner, characterized in that the silica fine powder has a fluorine-containing negatively charged polar group and is surface-treated with a quaternary ammonium salt. 2. The positively charged toner according to claim 1, wherein the positively charged polar group in the fine silica powder is derived from an aminosilane coupling agent. 3. The positively charged toner according to claim 1, wherein the hydrophobic group in the fine silica powder is derived from an alkylsilane coupling agent. 4. The positive charge according to claim 1, wherein the fluorine-containing negatively charged polar group in the wet silica fine powder is derived from a fluorine-containing silane coupling agent. toner. 5. A total treatment amount of the fluorine-containing silane coupling agent and a quaternary ammonium salt with respect to 100% by weight of the wet silica fine powder is set to a value within a range of 20 to 40% by weight. 5. The positively charged toner according to claim 4, wherein: 6. The weight ratio of the quaternary ammonium salt / fluorine-containing silane coupling agent used for the surface treatment of the wet silica fine powder is set to a value in the range of 0.6 to 1.5. The positively charged toner according to claim 4, wherein: 7. A method for producing a positively charged toner in which finely divided dry silica and finely divided silica are externally added, wherein finely divided dry silica having a positively charged polar group and a hydrophobic group is added as the finely divided dry silica. And adding a wet silica fine powder which has a fluorine-containing negatively charged polar group and has been surface-treated with a quaternary ammonium salt as the wet silica fine powder. Production method.