JP2002365836A - Positive chare type micr toner and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive charge type MICR(magnetic ink character recognition) toner ensuring stable image density of an MICR font and not causing a fog over a long period of time and to provide a method for producing the toner. SOLUTION: When the positive charge type MICR toner containing fine dry silica powder and fine wet silica powder as additives is 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 silicone oil and having a positive charge type polar group and 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 magnetic ink character recognition (MICR) system used for printing.
More specifically, the present invention relates to a positively charged MICR 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 of manufacturing the same.

[0002]

2. Description of the Related Art In checks, certificates, invoices automatically issued by credit companies, and right of way on expressways, combinations of numbers and symbols called fonts are printed with magnetic ink and read magnetically. In recent years, a management or sorting method has become popular. This method is generally known as MICR (Magnetic Ink Char).
actor Recognition) system, for example, JP-A-2-134648, JP-A-5-80
The system is reported in, for example, Japanese Patent Publication No. 582. In this MICR system, it is necessary to print a magnetic ink character (hereinafter, referred to as an MICR font) composed of a combination of fonts on a check, a certificate, or the like. A magnetic ink called MICR toner is used. That is, in an electrophotographic development type printer, a high quality MICR font is obtained by visualizing an electrostatic latent image by MICR toner or visualizing the electrostatic latent image by reversal development.

[0003] A general toner or MICR toner applied to the electrophotographic development system is composed of a thermoplastic resin as a binder, a dye or a pigment as a colorant or a charge control agent, a wax as a release agent, A compound material such as a magnetic material is kneaded, pulverized and classified to form a particle. An inorganic fine powder such as silica, titanium oxide, or alumina is added in order to impart fluidity to the toner or to improve the cleaning property. However, these inorganic fine powders are generally rich in hydrophilicity as they are, and the fluidity and charge rising property of the toner may be affected by surrounding environmental conditions (humidity). Therefore, in order to prevent the influence of such environmental conditions, treatment of the surface of these inorganic fine powders with a hydrophobizing agent or introduction of a charged polar group has been performed.

For example, in Japanese Patent Application Laid-Open No. 11-160908, a positively charged polar group is used in order to stabilize rising of charging, durability, environmental stability, and reading performance of MICR toner.
It is stated that it is effective to use a dry silica fine powder having a hydrophobic group and a wet silica fine powder having a positively charged polar group introduced therein and subjected to a hydrophobic treatment with silicone oil. Further, JP-A-11-143119 discloses a dry silica fine powder having a positively charged polar group and a hydrophobic group, and a positively charged polar group in order to improve the rise of charging rise and durability, and obtain environmental stability. It is said that it is effective to use a fine powder of wet silica containing a fluorine-containing polar group in combination.

[0005] Further, although not a MICR toner but a general toner, in order to introduce a polar group, a method of treating a metal oxide with an aminosilane coupling agent and using it as an external additive of the toner has been proposed. JP 52-13573
No. 9 and JP-A-56-123550. According to this method, the terminal amino group of the aminosilane coupling agent can provide a developer having strong positive charge. Similarly, in a general toner instead of the MICR toner, hydrophobic silica fine particles are surface-treated with both a positive charge control agent and a hydrophobizing agent,
A method of using it as an external additive of a developer is disclosed in
No. 16252, JP-A-63-73271, and JP-A-63-73271
No. 73272 discloses this. According to this method, a developer exhibiting strong positive chargeability can be obtained by the effect of the positive charge control agent.

Furthermore, in a general toner, not a MICR toner, both a negatively-chargeable polar group and a positively-chargeable polar group are bonded to the surface of the inorganic fine particles, and the non-magnetic particles are bonded to the non-magnetic particles. A method of using as an external additive of a toner for component development is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-66564. According to this method, it is possible to obtain a developer using a non-magnetic one-component developing toner, which is excellent in charge level improvement property, charge rising property, and toner fluidity.

[0007]

However, the above-mentioned prior art has the following problems (1) to (4). (1) Further, JP-A-11-160908 and JP-A-11-143119
An MI disclosed in Japanese Unexamined Patent Publication (Kokai), using a dry silica fine powder having a positively charged polar group and a hydrophobic group, and a wet silica fine powder containing a positively charged polar group and a fluorine-containing polar group.
With the CR toner, when the MICR toner is used at a low printing rate, there has been a problem that the image density and the stability of fog become insufficient. (2) A developer using a metal oxide treated with an aminosilane coupling agent disclosed in Japanese Patent Application Laid-Open No. 52-135739 or the like can be used in a high-temperature and 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. Therefore, it has been difficult to use such a processing method as it is for improving the MICR toner. (3) The developer obtained by subjecting the 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 the 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. Therefore, it has been difficult to use such a processing method as it is for improving the MICR toner. (4) Further, a developer containing inorganic fine particles having both a negatively-chargeable polar group and a positively-chargeable polar group bonded to the surface, as disclosed in JP-A-2-66564, etc., can be used in a high-temperature, high-humidity environment. Under these conditions, problems such as poor charging stability and toner fluidity were observed. Therefore, for such a processing method, M
It was difficult to use it as it is for improving the ICR toner.

Therefore, the inventors of the present invention diligently studied these problems, and particularly when performing printing with a low printing rate, a positively-charged dry silica fine powder and a wet-type silica fine powder are used. In addition to introducing positively charged polar groups and fluorine-containing negatively charged polar groups into the wet silica fine powder, the surface treatment with silicone oil stabilizes the image density of MICR toner for a long time. , No fogging was found, and the present invention was completed.

[0009]

According to the present invention, in a positively charged MICR toner containing a fine powder of dry silica and a fine powder of wet silica as an external additive, the fine powder of dry silica contains a positively charged polar group. A positively-charged MICR toner, characterized in that the wet-type silica fine powder has a positively-charged polar group and a fluorine-containing negatively-charged polar group and has been surface-treated with silicone oil. The above-mentioned problem can be solved. That is, the addition of a finely divided dry silica powder having a positively charged polar group and a hydrophobic group improves the charge rising property and reduces the change in the fluidity of the MICR toner due to the change in environmental conditions. Can be. On the other hand, the addition of a wet silica fine powder which has a positively charged polar group and a fluorine-containing negatively charged polar group and has been surface-treated with silicone oil can exert the effect of stabilizing the charging characteristics for a long time.
That is, the positive chargeability can be stabilized by replacing a part of the fluorine-containing negatively chargeable polar group (fluorine silane) having strong negative chargeability with silicone oil. Further, as compared with the contained negatively charged polar group (fluorine silane), silicone oil has higher hydrophobicity and environmental fluctuation is reduced. The synergistic effect of these two types of silica fine powder stabilizes the image density of the MICR toner for a long time, even when printing with a particularly low printing rate, and effectively prevents fogging. can do.

In constructing the positively charged MICR toner of the present invention, the positively charged polar group in the finely divided dry silica powder is
It is preferably 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 MICR toner of the present invention, it is preferable that the hydrophobic group in the dry silica fine 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 constructing the positively charged MICR toner of the present invention, the positively charged polar group in the wet silica fine powder is
It is preferably derived from an aminosilane coupling agent. With this configuration, the positively charged polar group can be easily and quantitatively introduced into the surface of the wet silica fine powder.

In constituting the positively charged MICR 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 constructing the positively charged MICR toner of the present invention, an aminosilane coupling agent and a fluorine-containing silane coupling are used with respect to 100% by weight of wet silica fine powder (synonymous with 100 parts by weight; hereinafter the same). It is preferable that the total treatment amount of the agent and the silicone oil be a value within the range of 20 to 40% by weight. 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,
The generation of fog can be effectively prevented.

In constructing the positively charged MICR toner of the present invention, the weight ratio of the fluorine-containing silane coupling agent / silicone oil used for the surface treatment of the fine wet silica powder is in the range of 1.0 to 4.0. It is preferable that 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 of the MICR toner is stabilized for a long time, and the occurrence of fog can be effectively prevented.

Another aspect of the present invention is a method for producing a positively charged MICR toner to which finely divided dry silica and finely divided silica are externally added, wherein the dry silica fine powder comprises a dry silica powder having a positively charged polar group and a hydrophobic group. Adding a silica fine powder, and, as a wet silica fine powder, having a positively charged polar group and a fluorine-containing negatively charged polar group, and adding a wet silica fine powder surface-treated with silicone oil, A method for producing a positively-charged MICR toner is provided, which can solve the above-mentioned problems. 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. A charged MICR toner can be efficiently provided.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Referring to the drawings, embodiments of the present invention will be specifically described below roughly divided into magnetic ink particles (sometimes simply referred to as ink 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 Ink Particles (1) Binder Resin Type 1 The type of the binder resin used for the ink 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 of styrene with another copolymerizable monomer. 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.

Examples of 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, 1,5
-Pentanediol, 1,6-hexanediol, 1,
Diols such as 4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol;
Bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylene bisphenol A; sorbitol, 1,2,3,6-hexane tetrol, 1,4-
Sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,2 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 if the low molecular weight peak is within the above range, the fixability of the ink 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 ink 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 within the above range, the offset resistance of the ink 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, in the binder resin, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) 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 ink particles may decrease, 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 manner, the storage stability, shape retention, and durability of the ink 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 ink particles, and it is also preferable to add a cross-linking agent or 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 In order to improve the dispersibility of the magnetic particles, the binder resin preferably has a functional group (polar group). 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 ink 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 ink 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 ink particles may fuse with 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 ink 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 ink 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, the hydrophobic particles can be appropriately moderated, and as a result, the moisture resistance of the ink particles can be improved. is there.

Residual magnetization It is preferable to set the residual magnetization of the magnetic particles to a value within the range of 7 to 20 emu / g. Specifically, 795.8k
After applying A / m (10 kOe), the amount of magnetic memory when the magnetic field is zero, that is, the residual magnetization is 7 to 20 em
Those in the range of u / g are preferred. Further, two or more types of magnetic particles having different values of residual magnetization are mixed, and the residual magnetization is reduced by 7%.
It is also preferable to set the value within the range of 20 emu / g to 20 emu / g.
For example, a first magnetic particle having a remanent magnetization in a range of 24 to 40 emu / g, and a first magnetic particle having a remanent magnetization of 1 to 24 emu / g
(However, 24 emu / g is not included.) It is preferable to combine with the second magnetic particles within the range. By mixing two or more types of magnetic particles in this way, the value of the residual magnetization can be easily adjusted, and the dispersibility of the magnetic particles can be improved.

Average particle size The average particle size 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 the ink particles and uniformly charge them. 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 to 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 ink 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 added is preferably set to a value within the range of 15 to 40% by weight based on the total amount of ink particles. The reason is that the addition amount of the magnetic particles is 15% by weight.
This is because, when the content is below, the durability may be reduced and fog may easily occur. On the other hand, if the addition amount of the magnetic particles exceeds 40% 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 20 to 30% by weight.

(3) Wax It is preferable to add a wax in order to obtain the effect of fixing property and offset property and to reduce the rejection rate of the reading device in the ink particles. Here, the type of the wax to be added is not particularly limited, and examples thereof include polyethylene wax, polypropylene wax, Teflon (registered trademark) wax, Fischer-Tropsch wax, paraffin wax, and the like.
It is preferable to use ester wax, montan wax, rice wax and the like. Further, these waxes may be used in combination. By adding such a wax, the offset 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.

Also, 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 ink 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, it may not be possible to efficiently prevent offset properties, image smearing, and the like. If the content is more than the weight percentage, the ink particles are fused to each other, and the storage stability tends to decrease.

(4) Charge Control Agent In addition, the charge level and the charge rise property (indicator of whether or not the charge is maintained at a constant charge level in a short time) of the ink particles are remarkably improved, and the ink particles have excellent durability and stability. It is preferable to add a charge control agent because 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 a positively charged toner 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 can be given. 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-acryl 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, styrene-acrylic resins (styrene-acrylic copolymers) having a quaternary ammonium salt, carboxylate or 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 negative chargeability, 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. In addition, aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids and polycarboxylic acids and metal salts thereof, anhydrides thereof,
Examples thereof include esters and phenol derivatives such as bisphenol.

Addition amount When the total amount of the ink particles is 100% by weight, the addition amount of the charge control agent is preferably set to a value within the range of 1.5 to 15% by weight. The reason for this is that if the added amount of the charge control agent is less than 1.5% by weight, it is difficult to stably impart charging characteristics, and the image density tends to be low or the durability tends to be low. Because there is. 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 and the like becomes better,
The added amount of the charge control agent is more preferably set to a value within the range of 2.0 to 8.0% by weight, and even more preferably set to a value within the range of 3.0 to 7.0% by weight.

(5) Property Improving Agent Colloidal silica or hydrophobic silica as a property improving agent is added to the ink particles for the purpose of improving fluidity and storage stability. It is preferable to carry out a surface treatment using the same.

(6) Average Particle Size The average particle size of the ink particles is not particularly limited, but is preferably in the range of, for example, 5 to 12 μm. The reason for this is that if the average particle diameter of the ink particles is less than 5 μm, the storage stability may be easily reduced. On the other hand, if the average particle size of the ink 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 ink particles is 6
More preferably, the value is in the range of 11 μm.

2. External additive agent In addition, in the ink particles, the charge amount distribution is uniform, showing stable charging characteristics without lowering the triboelectric charge amount and without charging up, and improving the fluidity, environment dependency, and durability. In order to provide an excellent positively charged MICR toner, both dry silica fine powder and wet silica fine powder need to be externally added to the ink particles.

(1) Dry Silica Fine Powder Surface Treatment Agent In order to introduce a positively charged polar group into 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 (O
CH 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 fine silica 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 into 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 not be exhibited. 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, resulting in an overcharged state and sufficient hydrophobicity. This is because durability stability may decrease. Therefore, the amount of the coupling agent having the positively charged polar group is adjusted to
The value is more preferably in the range of 7 to 23% by weight, and more preferably in the range of 10 to 20% by weight, with respect to 00% by weight.

The amount of the hydrophobic group introduced into the surface of the dry silica fine powder, that is, the amount of the coupling agent having a hydrophobic group (alkylsilane coupling agent) added to the dry silica fine powder is 100% by weight. 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 not be exhibited. 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 sufficient positive charging property may not be obtained. Therefore, the amount of such a coupling agent having a hydrophobic group can be reduced by the dry silica fine powder 10
The value is more preferably in the range of 12 to 27% by weight, more preferably in the range of 15 to 25% by weight, based on 0% by weight.

Addition amount The addition amount of the dry silica fine powder having a positively charged polar group and a hydrophobic group was determined based on 100% by weight of the ink particles.
It is preferable to set the value in the range of 0.3 to 3% by weight.
The reason for this is that the amount of the fine silica powder added is 0.
If the value is less than 3% by weight, the fluidity may decrease, and a uniform image may not be obtained, or a problem such as aggregation of the MICR toner may occur due to a decrease in storage stability. On the other hand, when the amount of the fine silica powder exceeds 3% by weight, the fluidity is improved, but excessive external addition causes problems such as a decrease in concentration, poor durability, and poor fixing. Because there is. Therefore, the amount of the fine silica powder added is adjusted to 100% by weight of the ink particles.
Is preferably in the range of 0.4 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 dry silica fine powder having a positively charged polar group and a hydrophobic group is preferably set to a value within the range of 10 to less than 100 nm. The reason for this is that if the average particle diameter 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 ink particles. It is. On the other hand, when the average particle size of the dry silica fine powder is excessively small, for example, a value of less than 10 nm, the burial phenomenon on the ink particle surface proceeds, and the fluidity, environment dependency, and durability are excellent. This is because it may be difficult to provide an electrostatic latent image developing toner. Therefore, the average particle size of the fine silica powder is 15 to 90.
The value is more preferably in the range of nm to 20 to 8
More preferably, the value is in the range of 0 nm.

(2) Surface Treatment Agent for Wet Silica Fine Powder In order to introduce a positively charged polar group into the wet silica fine powder, the above-mentioned coupling agent having a positively charged polar group, for example, aminosilane It is preferable to use a coupling agent.

In order to introduce a fluorine-containing negatively charged polar group into the wet silica fine powder, a fluorine-containing silane coupling agent such as a compound represented by the following formula and a mixture thereof are used as a surface treatment agent. Is preferred. _{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

Further, examples of the silicone oil as the surface treating agent include compounds represented by the following formulas (1) to (4).

[0058]

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[0059]

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[0060]

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[0061]

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The amount of the positively charged polar group introduced into the wet silica fine powder, that is, the amount of the coupling agent having a positively charged polar group (aminosilane coupling agent) added to the wet silica fine powder is 100% by weight. Therefore, it is preferable to set the value in the range of 5 to 25% by weight. The reason for this is that when the amount of the coupling agent having a positively charged polar group is less than 5% by weight, the effect of adding the wet silica fine powder may be reduced. On the other hand, if the amount of the coupling agent having the positively charged polar group exceeds 25% by weight, the effect of the fluorine-containing negatively chargeable group may be suppressed. Therefore, the amount of the coupling agent having the positively charged polar group is more preferably set to a value within the range of 8 to 18% by weight, more preferably 10 to 15% by weight, based on 100% by weight of the wet silica fine powder. It is more preferable to set the value within the range.

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 coupling agent having a fluorine-containing negatively charged polar group (fluorine-containing silane coupling agent) is determined by the wet silica fine powder. Powder 100
It is preferable to set the value in the range of 10 to 30% by weight with respect to% by weight. The reason for this is that when the amount of the coupling agent having the fluorine-containing negatively charged polar group is less than 5% by weight, the introduction of the fluorine-containing negatively charged polar group becomes insufficient, and the effect of adding the wet silica fine powder is reduced. This is because they may not be expressed. On the other hand, when the addition amount of the coupling agent having the fluorine-containing negatively charged polar group exceeds 25% by weight, the introduction of the fluorine-containing negatively charged polar group is increased, and proper hydrophobicity may not be obtained. Because there is. Therefore, the amount of the coupling agent having a fluorine-containing negatively charged polar group is adjusted to 100 parts by weight of the wet silica fine powder.
The value is more preferably in the range of 7 to 23% by weight, and even more preferably in the range of 10 to 20% by weight, based on the weight%.

In addition, silica-
It is preferable that the amount of the oil added is within a range of 3 to 10% by weight based on 100% by weight of the wet silica fine powder. The reason for this is that if the addition amount of the silicone oil is less than 3% by weight, the effect of adding the silicone oil may not be exhibited. On the other hand, if the amount of the silicone oil exceeds 10% by weight, the charge stabilizing function of the fluorine-containing silane coupling agent used in combination may not be obtained. Therefore, it is more preferable that the amount of the silicone oil to be added falls within a range of 5 to 10% by weight based on 100% by weight of the wet silica fine powder.

Total treatment amount A coupling agent having a positively charged polar group (an aminosilane coupling agent) with respect to the wet silica fine powder,
The total amount of the coupling agent having a fluorine-containing negatively charged polar group (fluorine-containing silane coupling agent) and silicone oil, that is, the total treatment amount of three types of surface treatment agents with respect to 100% by weight of wet silica fine powder, 20-40
It is preferable to set the value in the range of% by weight. The reason for this is that if the total treatment amount of the three types of surface treatment agents is less than 20% by weight, the hydrophobicity may decrease and the environmental fluctuation may increase. On the other hand, if the total amount of the three types of surface treatment agents exceeds 40% by weight, the fluidity deteriorates, and image defects such as white stripes and white spots may occur. Therefore, it is more preferable that the total treatment amount of the three surface treatment agents is set to a value within the range of 20 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 subjected to surface treatment, the weight ratio of the coupling agent having a fluorine-containing negatively charged polar group / silicone oil is set to a value within the range of 1.0 to 4.0. Is preferred. The reason for this is that if the weight ratio is less than 1, the charge stabilizing function of the fluorinated polar group may not be obtained. On the other hand, if the weight ratio exceeds 4, the effect of adding the silicone oil may not be exhibited. Accordingly, the weight ratio of the coupling agent having a fluorine-containing negatively charged polar group / silicone oil is more preferably set to a value within the range of 1.5 to 3.5, and more preferably to a value within the range of 1.5 to 3. More preferably,

Addition amount The addition amount of the wet silica fine powder having a positively charged polar group and a fluorine-containing negatively charged polar group and treated with silicone oil was set to 0.2 to 100% by weight of the ink particles.
It is preferable to set the value in the range of 1.0 to 1.0% by weight. The reason for this is that the addition amount of such wet silica fine powder is 0.2
If the value is less than% by weight, the effect of suppressing charge-up as a toner may be lost. On the other hand, when the addition amount of the wet silica fine powder exceeds 1.0% by weight, the charge amount of the toner decreases, and a sufficient image density may not be obtained. Therefore, the amount of the wet silica fine powder to be added is determined by the
The value is more preferably in the range of 0.4 to 0.9% by weight, and even more preferably in the range of 0.3 to 0.7% by weight, with respect to 00% by weight.

Average Particle Size It is preferable that the wet silica fine powder having a positively charged polar group and a fluorine-containing negatively charged polar group and treated with silicone oil has an average particle size within a range of 200 to less than 500 nm. The reason for this is that if the average particle diameter of such wet silica fine powder is 500 nm or more, uniform charging characteristics may be exhibited, or dispersion and mixing with ink 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, it is more preferable to set the average particle size of the wet silica fine powder to a value in the range of 250 to 450 nm, and
More preferably, the value is in the range of 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 a 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 MICR toner 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 weight ratio of the dry silica fine powder and the wet silica fine powder is 20:80 to 80: 2.
It is preferably set to a value within the range of 0, and 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 a value within the range of 0.5 to 5% by weight with respect to 100% by weight of the ink particles. It is preferable that 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 ink particles 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
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 MICR toner of the present invention is applied. The image forming apparatus 1 includes a developing device 10 and a transfer roller 1 around a positively charged photosensitive drum (photosensitive member) 9 that rotates clockwise along the rotation direction.
9, a cleaning blade 13 and a charging unit 8 are provided. 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, by opening and closing the power switch 49, the main motor (not shown) starts driving, 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.

[0075]

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
m 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 then 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 ) ₂ Si
(OCH ₃ ) ₂ was dissolved in 30 g of toluene to prepare a diluted solution. Then, in a container, fumed silica
(Aerosil # 130; manufactured by Nippon Aerosil Co., Ltd.) While stirring 100 g, the obtained diluted solution was gradually added dropwise, and further 1
The mixture was stirred vigorously for 0 minutes. Thereafter, the mixture was heated in a high-temperature bath at 150 ° C., and then crushed to obtain silica B.

(3) Production of silica a H ₂ N (CH ₂ ) ₂ N was added to 100 ml of toluene in a container.
10 g of H (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and CF ₃ (C
After 15 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 5 g of dimethyl silicone oil were respectively 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 a.

(4) Production of silica b H ₂ N (CH ₂ ) ₂ N was added to 100 ml of toluene in a container.
10 g of H (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and CF ₃ (C
After 15 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 10 g of dimethyl silicone oil were respectively 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 b.

(5) Production of silica c H ₂ N (CH ₂ ) ₂ N was added to 100 ml of toluene in a container.
10 g of H (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and CF ₃ (C
After dissolving 20 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 5 g of dimethyl silicone oil, 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 c.

(6) Production of silica d H ₂ N (CH ₂ ) ₂ N was placed in 100 ml of toluene in a container.
10 g of H (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and CF ₃ (C
After dissolving 10 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 5 g of dimethyl silicone oil, 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 d.

(7) Production of silica e 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 (OCH ₃ ) ₃ and CF ₃ (C
After 15 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 10 g of dimethyl silicone oil were respectively 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 e.

(8) Production of silica f 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 20 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 5 g of dimethyl silicone oil, 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 f.

(9) Production of silica g H ₂ N (CH ₂ ) ₂ N was placed in 100 ml of toluene in a container.
20 g of H (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and CF ₃ (C
After dissolving 10 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 10 g of dimethyl silicone oil, 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 g.

(10) Production of silica h H ₂ N (CH ₂ ) ₂ N was placed in 100 ml of toluene in a container.
20 g of H (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and CF ₃ (C
After 15 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 5 g of dimethyl silicone oil were respectively 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 h.

(11) Production of silica i H ₂ N (CH ₂ ) ₂ N was placed in 100 ml of toluene in a container.
25 g of H (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and CF ₃ (C
After dissolving 10 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 5 g of dimethyl silicone oil, 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 i.

(12) Production of silica j H ₂ N (CH ₂ ) ₂ N was added to 100 ml of toluene in a container.
10 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 j.

(13) Production of silica k 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 (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 (OCH ₃ ) ₃ and CF ₃ (C
After dissolving 15 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 15 g of dimethyl silicone oil, 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.

(15) Production of silica m H ₂ N (CH ₂ ) ₂ N was added to 100 ml of toluene in a container.
10 g of H (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and CF ₃ (C
After dissolving 10 g of H ₂ ) ₂ Si (OCH ₃ ) ₃ and 20 g of dimethyl silicone oil, 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 m.

Example 1 (1) Production of Ink 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, the mixture was pulverized and classified to obtain ink particles having an average particle diameter of 8 μm. Further, the particle size distribution of the obtained ink 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) 75% by weight Charge control agent (TP-415; Hodogaya Chemical) 4% by weight Wax (Viscol TS-200; manufactured by Sanyo Chemical Industries) ) 4% by weight

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

[Examples 2 to 12] The same ink particles as those in Example 1 were prepared, and the above-mentioned silicas A and B and silicas a to i were mixed with the ink particles as shown in Table 1. Positively-charged MICR toner (magnetic two-component developer) was prepared and evaluated in combination. Table 1 shows the obtained results.

[Comparative Examples 1 to 4] The same ink particles as in Example 1 were prepared, and the silica A and B described above were added alone to the ink particles as shown in Table 1, or Positively charged MI added in combination with silica j ~ l
A CR toner (magnetic two-component developer) was prepared and evaluated. Table 1 shows the obtained results.

As a result, in Comparative Examples 1 and 2,
It was confirmed that it was difficult to stabilize the charging characteristics for a long period of time because no specific wet silica fine powder was used in combination, and that it was difficult to use it under high temperature and high humidity conditions. In Comparative Examples 3 and 4, the wet silica fine powder (silica j and k) was not subjected to surface treatment with silicone oil, so that it was difficult to stabilize the charging characteristics for a long time, or It has been confirmed that it is difficult to use under high temperature and high humidity conditions.

[Examples 13 and 14] The same ink particles as in Example 1 were prepared, and the above-mentioned silicas A and B and silicas a to i were mixed with the ink particles as shown in Table 1. Positively-charged MICR toner (magnetic two-component developer) was prepared and evaluated in combination. Table 2 shows the obtained results.

As understood from the results, in Example 13, the wet silica fine powder (silica 1) used
This is probably because the total amount of the quaternary ammonium salt, the fluorine-containing silane coupling agent, and the silicone oil is relatively large at 45% by weight with respect to 100% by weight of the silica fine powder. It was confirmed that fog was generated under high humidity conditions. Further, in Example 14, the weight ratio of the fluorine-containing silane coupling agent / silicone oil in the wet silica fine powder (silica m) used was:
0.5, which is considered to be relatively low, it was confirmed that the image density under high-temperature and high-humidity conditions was slightly low and fogging also occurred.

[0098]

[Table 1]

[0099]

[Table 2]

[0100]

[Table 3]

[0101]

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 ink particles. By doing so, a positively charged MICR toner capable of obtaining good image density and fog resistance over a long period of time can be provided even when printing at a low printing rate is performed. In particular, in the positively charged toner of the present invention,
The total treatment amount of the aminosilane coupling agent, the fluorine-containing silane coupling agent, and the silicone oil with respect to 100% by weight of the wet silica fine powder is in the range of 15 to 30% by weight, and the fluorine-containing silane coupling agent / By ensuring that the weight ratio of the silicone oil is in the range of 1.0 to 4.0, even when printing with a low printing rate is performed, it is possible to reliably obtain better image density and fog resistance over a long period of time. Is now available.

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

[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.

[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 (8)

[Claims] 1. A positively-charged MICR toner containing fine silica powder and fine silica powder as external additives, wherein the fine silica powder has a positively-charged polar group and a hydrophobic group, A positively charged MICR toner, characterized in that the wet silica fine powder has a positively charged polar group and a fluorine-containing negatively charged polar group, and has been surface-treated with silicone oil. 2. The positively-charged MICR 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 MICR according to claim 1, wherein the hydrophobic group in the fine silica powder is derived from an alkylsilane coupling agent.
toner. 4. The positively-charged MICR toner according to claim 1, wherein the positively-charged polar group in the wet silica fine powder is derived from an aminosilane coupling agent. 5. The positively charged positive electrode according to claim 1, wherein the fluorine-containing negatively charged polar group in the finely divided wet silica is derived from a fluorine-containing silane coupling agent. MICR toner. 6. The total treatment amount of the aminosilane coupling agent, the fluorine-containing silane coupling agent and the silicone oil with respect to 100% by weight of the wet silica fine powder is in the range of 20 to 40% by weight. 6. The positively charged MICR toner according to claim 5, wherein the value is a value. 7. The weight ratio of the fluorine-containing silane coupling agent / silicone oil used for the surface treatment of the finely divided wet silica powder to a value within the range of 1.0 to 4.0. Item 7. Positively charged MICR according to item 5 or 6
toner. 8. A method for producing a positively charged MICR 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 silica. And a step of adding, as the wet silica fine powder, a wet silica fine powder having a positively charged polar group and a fluorine-containing negatively charged polar group and having been surface-treated with silicone oil. A method for producing a charged MICR toner.