JPH0887126A - Positive charge toner and developer composition - Google Patents

Abstract

PURPOSE: To keep the quantity of electric charges on a toner and the resistance of a carrier constant over a long period of time and to maintain high image quality by adding fine silica particles having a specified average particle diameter and a specified particle size distribution to the surface of the toner. CONSTITUTION: Fine silica particles having 30-100nm number average particle diameter of primary particles and a particle size distribution in which particles each having <=20nm particle diameter account for <=20% are stuck to the surface of a positive charge type toner contg. at least a bonding resin and a colorant by 0.1-3.0 pts.wt. per 100 pts.wt. of the toner. The silica particles have been made hydrophobic by surface treatment. The quantity of electric charges on the toner and the resistance of a carrier are kept constant over a long period of time and high image quality is maintained because the cleanability of the toner on the surface of a photoreceptor is improved. When the bonding resin and the carrier are properly selected, low-temp. fixability and environmental stability are improved and service life is prolonged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positively chargeable toner used in a dry two-component developing method used for developing an electrostatic latent image in an image forming apparatus such as a laser printer or a dry electrostatic copying machine, and a developing agent. With respect to the agent composition, more specifically, it is possible to maintain high image quality by maintaining the charge amount and carrier resistance of the toner at a constant value for a long period of time and improving the cleaning property of the toner remaining on the surface of the photoconductor. Positively charged toner and developer composition.

[0002]

2. Description of the Related Art An electrophotographic method used in an image forming apparatus such as a laser printer or a dry electrostatic copying machine is disclosed in US Pat. Nos. 2,221,776 and 2,29.
No. 7,691, No. 2,357,809, etc., the photoconductive insulating layer is uniformly charged (charging step) and then the layer is exposed to dissipate the charge in the exposed areas. To form an electrostatic latent image (exposure step), and to make the electrostatic latent image visible by adhering colored fine powder, so-called toner, to this electrostatic latent image (developing step). Of the transfer material (transferring step), and then permanently fixing (fixing step) by heating, pressure or other appropriate means. Therefore, the toner must have the functions required not only in the developing process but also in the transferring process and the fixing process.

The developing methods applied to these electrophotographic methods are roughly classified into a dry developing method and a wet developing method. The former method further includes a method using a one-component developer and a method using a two-component developer composed of a toner and a carrier. As a method of using a two-component developer, a magnetic brush developing method using a magnetic powder carrier (US Pat. No. 2,786,439) and a somewhat rough bead carrier are used, depending on the type of a toner conveying system. Cascade developing method (U.S. Pat. No. 2,618,551) and the like are available.

As the toner applied to these developing methods, a binder such as a styrene-acrylate copolymer resin (polystyrene resin), a polyester resin or an epoxy resin is used in a coloring agent such as a dye or a pigment, and a charge 1-8 by mixing and dispersing various functional additives such as control agents and wax.
A fine powder pulverized to about 0 μm is generally used.

Such a two-component developer is generally required to have long life, that is, stability and maintainability of image quality in continuous development. For that purpose, it is necessary to maintain the charge amount between the toner and the carrier particles and the developer resistance within an appropriate range, and it is most desirable that the initial charge amount and the developer resistance do not change even in the latter half of the long run.

For the purpose of stably maintaining the charge amount and resistance of these developers, the design and selection of a binder resin, a charge control agent and other additives have been studied from the toner side. On the other hand, on the carrier side as well, various studies have been made on the oxidation treatment method of iron powder or constituent materials such as ferrite and magnetite, the surface shape of these magnetic powders, the coating material and the treatment method thereof.

For example, regarding the binder resin of the toner, in order to further improve the drawbacks of polyester having excellent offset resistance and low-temperature fixability, a polyester resin is mixed with a styrene acrylic resin having excellent charge stability under high temperature and high humidity. Various methods have been proposed, and the present inventors have also developed a technique of using a resin obtained by simultaneously advancing addition polymerization and polycondensation in the same reaction vessel as a binder for toner, and have already applied for it. (Japanese Patent Laid-Open No. 4-142301, etc.).

Regarding the carrier, in order to reduce the deterioration of the developer when developing at a high speed, porous amorphous iron powder called "sponge" is used as the carrier to reduce the bulk specific gravity. Therefore, attempts have been made to reduce the stirring torque. These attempts, at the same time,
It also improves the increase of the edge effect of the solid black portion due to the charge-up of carriers near the photoconductor that occurs during high-speed development. That is, in the case of porous amorphous iron powder, the contact point between particles can be increased by the interposition of the convex portion, the effect of bias can be improved, and the substantial development electric field strength can be increased. The carrier having is suitable for use in high-speed printers and copiers using the pseudo-conductive method.

Further, a method of externally adding various silica fine particles to the toner surface has been conventionally performed for the purpose of preventing the fluidity and cleaning property of the toner from being deteriorated due to the reduction of the particle diameter of the toner. By this method, the fluidity and the like can be improved, so that the negatively chargeable toner can maintain good toner chargeability and toner transportability.

However, with regard to the positively chargeable toner and its developer, since the normal silica fine particles have a negative charge, the externally added silica fine particles cover the surface of the toner so that the charge on the toner surface is changed. There is a problem that the toner is canceled and the toner charge amount is substantially reduced. Further, during the development for a long period of time, the silica fine particles on the toner surface are transferred to the carrier, which causes a problem that the surface resistance of the carrier is increased. Further, a positively chargeable silica (Japanese Patent Laid-Open No. 50-116046), which is less likely to impair the chargeability of the positively chargeable toner, has been proposed.
Also, the silica fine particles on the toner surface tend to be electrostatically transferred to the surface of the carrier electrostatically, and there is a problem that the surface resistance of the carrier increases and the charge imparting ability of the carrier decreases.

On the other hand, paying attention to the particle size of the silica fine particles, various attempts have been proposed to maintain good images obtained by using various developing methods by using a toner in which the particle size of the silica fine particles to be added is controlled. Has been done.

For example, in JP-A-60-263956, an electrostatic image formed on a photoconductor whose surface is appropriately roughened contains silica fine particles having an average primary particle diameter of 40 to 100 nm. A developing method of developing with a developer is disclosed. However, this method is intended to prevent the surface of the photoconductor from being smoothed by embedding small particle size silica in the recesses on the surface of the selenium photoconductor that has been polished. It is not intended to maintain the surface resistance of the carrier. Further, the toner used is also a negatively chargeable toner and does not solve the problems inherent in the positively chargeable toner.

Further, Japanese Patent Laid-Open No. 188546/1986,
Japanese Unexamined Patent Publication No. 2-151872 and the like disclose a toner or a developer in which both large particle size silica and small particle size silica are externally added, but each contains a certain amount or more of small particle size silica. Therefore, the problems such as the reduction of the charge amount of the toner due to the coating of the toner surface and the increase of the surface resistance due to the transfer to the carrier have not been solved.

Therefore, the object of the present invention is to maintain a high image quality by maintaining the charge amount and carrier resistance of the toner at a constant value for a long period of time and improving the cleaning property of the toner on the surface of the photoconductor. Another object of the present invention is to provide a positively chargeable toner and a developer composition.

[0015]

Means for Solving the Problems As a result of intensive studies to achieve the object, the inventors have found that silica fine particles having a specific average particle size and particle size distribution are externally added to the toner surface. It has been found that even in the case of a positively chargeable toner, the problems of substantial reduction in the amount of charge of the toner and increase in carrier surface resistance do not occur, and the present invention has been completed.

That is, the gist of the present invention is (1) In a positively chargeable toner containing at least a binder resin and a colorant, the number average particle diameter of primary particles is 30 to 100 n.
a positively chargeable toner characterized in that silica fine particles having a particle size m and a frequency of particles having a particle size of 20 nm or less in the particle size distribution of 20% or less are attached to the toner surface,
(2) The positively chargeable toner according to (1) above, wherein the amount of the silica fine particles attached is 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the toner, and (3) the silica fine particles have a hydrophobic surface. The positively chargeable toner according to the above (1) or (2), which is treated silica, (4) the main component of the binder resin is a softening point of 95 to 160 ° C. by a Koka type flow tester,
The positively chargeable toner according to any one of (1) to (3) above, which is a polyester resin having a glass transition temperature of 50 to 80 ° C. by DSC, (5) The main component of the binder resin undergoes addition polymerization and polycondensation. A resin obtained by carrying out in the same reaction vessel, wherein addition polymerization is to obtain a vinyl resin by radical polymerization, and polycondensation is to obtain a polyester, polyesteramide or polyamide (1) to (3) The positively chargeable toner according to any one of (6)
(7) A developer composition comprising the positively chargeable toner according to any one of (1) to (5) and a carrier capable of carrying the toner, (7) the carrier is a porous amorphous iron having irregularities on the surface The developer composition according to (6) above, which is a powder.
(8) The developer composition according to (7), wherein the irregular iron powder has an average particle size of 50 to 200 μm, and the difference between the irregularities is 10 μm or more.

The positively chargeable toner of the present invention is a positively chargeable toner containing at least a binder resin and a colorant, wherein the primary particles have a number average particle size of 30 to 100 nm and particles in the particle size distribution. It is characterized in that silica fine particles having a diameter of 20 nm or less and a frequency of 20% or less adhere to the toner surface.

The number average particle diameter of the primary particles of the silica fine particles used is usually 30 to 100 nm, preferably 30 to 7
It is 0 nm, more preferably 35 to 60 nm. If it is smaller than this range, the silica fine particles covering the toner surface will cancel the charge on the toner surface, substantially reducing the charge amount of the toner and increasing the surface resistance of the carrier due to transfer to the carrier during long-term development. Tend to do. On the other hand, if it is larger than this range, the fluidity is not sufficiently improved, the surface of the photoconductor is damaged, and in the photoconductor cleaning blade system, the wear of the blade tends to be accelerated. It is generally known that the silica fine particles having such a number average particle size have a smaller charge amount (per unit weight) in the initial stage and during dispersion as compared with those having a smaller particle size. From this point as well, it is presumed that the silica fine particles are more effective for maintaining the charge amount of the toner.

Here, the particle diameter of the primary particles of silica fine particles is a value measured from the projected circle equivalent diameter of the particles by observation with a scanning electron microscope (SEM), and the number average particle diameter thereof is the value. It is a value calculated by calculating the number distribution from the number average.

Regarding the particle size distribution of silica fine particles, the frequency of particles having a particle size of 20 nm or less in the particle size distribution is usually 20% or less, preferably the frequency of particles having a particle size of 20 nm or less is 10% or less, More preferably 5%
It is as follows. When the content of the silica fine particles having a particle size of 20 nm or less exceeds this range, there is a tendency that the charge amount of the toner is substantially reduced and the surface resistance of the carrier is increased as in the case where the average particle size is small.

The silica fine particles used in the present invention are not particularly limited as long as they satisfy the conditions regarding the above particle diameter, and any known silica fine particles may be used. For example, it may be one that has not been surface treated at all, or one that has been subjected to various chemical treatments. The material of the silica fine particles is not particularly limited as long as it contains silicon dioxide as a main component.

For example, the following compounds are generally used as the organosilicon compound used for the hydrophobic treatment. Hexamethyldisilazane, trimethylsilane, trimethylethoxysilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylchlorosilane, dimethylethoxysilane, dimethyldimethoxysilane , Hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane,
There are 1,3-diphenyltetramethyldisiloxane, and polydimethylsiloxane having 2 to 12 siloxane units per molecule and each terminally located unit containing one Si-bonded hydroxyl group. These are used alone or as a mixture of two or more.

However, in the present invention, since the silica fine particles are hydrophilic as they are, it is known that they absorb water in the air under high temperature and high humidity to cause deterioration of fluidity and aggregation of the toner. Therefore, silica fine particles whose surface has been hydrophobized are preferably used. In particular, silica fine particles obtained by treatment with an organosilicon compound having an organic group such as a trimethyl group and having a hydrophobicity of 80 or more as determined by a methanol titration test are more preferably used.

The amount of silica fine particles adhered in the present invention is
It is preferably 0.1-3.
It is 0 part by weight, more preferably 0.2 to 1.0 part by weight, and most preferably 0.2 to 0.6 part by weight. If the amount is more than this range, the positive charging property of the toner tends to be lowered, and excessive silica fine particles tend to be released from the toner and easily migrate to the carrier surface, increasing the surface resistance of the carrier. If it is less than this range, it tends to be difficult to improve the fluidity of the toner.

In the present invention, the following effects can be obtained because the silica fine particles as described above adhere to the toner surface. Since the toner coverage per unit weight of the silica fine particles is reduced, it is possible to prevent the substantial decrease in the toner charge amount by maintaining the desired fluidity and reducing the influence of the negative charges of the silica fine particles. . Even during long-term development, the silica fine particles on the toner surface do not migrate to the carrier, and even if they migrate, the coverage rate on the carrier is small, and the increase in the surface resistance of the carrier can be prevented. Since the fine silica particles having a large particle size intervene to improve the releasability of the toner adhering to the surface of the photoconductor, the cleaning property is improved.

In the present invention, the positively chargeable toner treated with the above silica fine particles is at least a binder resin,
Any known positively charging toner can be used without any particular limitation as long as it contains a colorant.

As the binder resin for toner used in the present invention, styrenes such as styrene, chlorostyrene and α-methylstyrene: monoolefins such as ethylene, propylene, butylene and isobutylene: vinyl acetate and vinyl propionate. Vinyl esters such as vinyl benzoate and vinyl butyrate: methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, dodecyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacryl Α-Methylene aliphatic monocarboxylic acid esters such as acid dodecyl: vinyl methyl ether, vinyl ethyl ether,
Vinyl ethers such as vinyl butyl ether: homopolymers or copolymers of vinyl ketone such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone. Further, natural and synthetic waxes, polyester, polyamide, epoxy resin, polycarbonate, polyurethane, silicone resin, fluorine resin, petroleum resin and the like can be used.

In the present invention, it is preferable to use a polyester resin as the main component of the binder resin or a resin obtained by carrying out addition polymerization and polycondensation in the same reaction vessel. More preferably, the main component of the binder resin is a polyester resin having a softening point of 95 to 160 ° C. by a Koka type flow tester and a glass transition temperature of 50 to 80 ° C. by DSC, or addition polymerization and polycondensation. Used in the same reaction vessel, the addition polymerization is a resin for obtaining a vinyl resin by radical polymerization, and the condensation polymerization is a resin for obtaining a polyester, polyesteramide or polyamide.

Taking the both as examples, the former will be described in more detail as the Ith mode and the latter as the IIth mode.

The polyester resin used in the first aspect has a cross-linked structure with at least one polyfunctional monomer having a valence of 3 or more in order to satisfy the thermal property required for fixing, which is an important required property of the toner. Things are preferable,
Further, the softening point by the Koka type flow tester is 95 ° C or higher and 160 ° C or lower, and the temperature difference between the outflow start temperature and the softening point is 15 ° C.
It is preferably -50 ° C. If the softening point is less than 95 ° C, the offset resistance and blocking resistance are impaired,
On the other hand, if the temperature exceeds 160 ° C., the low-temperature fixability is impaired, which is not preferable. Similarly, if the temperature difference between the outflow start temperature and the softening point is less than 15 ° C, the offset resistance and blocking resistance may be impaired, and if it exceeds 50 ° C, the low-temperature fixing property may be impaired, which is not preferable. .

The Koka type flow tester is a very effective device for evaluating the binder resin for toner, because the melting behavior of the resin and the like can be measured with good reproducibility at each temperature. Specifically, for the softening point, using a Koka type flow tester (Shimadzu Corporation), a sample of 1 cm ³ is heated at a heating rate of 6 ° C./min, a load of 20 kg / cm ² is applied by a plunger, and a diameter of 1 mm. , A nozzle with a length of 1 mm is extruded, whereby a plunger descending amount (flow value) -temperature curve of the flow tester is drawn, and the height of the S-shaped curve is h.
Is the temperature corresponding to h / 2.

The polyester resin preferably has a glass transition temperature by DSC of 50 ° C. or higher and 80 ° C. or lower. If the temperature is lower than 50 ° C, the obtained toner is likely to aggregate and the stability during long-term storage is poor, and if the temperature is higher than 80 ° C, fixing failure is likely to occur, and the pulverizability during production is not good, which is not preferable.

The polyester resin used in the present invention is
Alcohol and carboxylic acid, or carboxylic acid anhydride,
A carboxylic acid ester or the like can be obtained as a raw material monomer. Examples of the dihydric alcohol component include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxypropylene (3.3) -2,2-
Bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4 -Hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis
(4-Hydroxyphenyl) alkylene oxide adduct of bisphenol A such as propane, 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, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, bisphenol A propylene adduct, bisphenol A ethylene adduct,
Hydrogenated bisphenol A and the like can be mentioned.

Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, and 1,4.
-Sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,
4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like can be mentioned.

The acid component is a divalent carboxylic acid monomer such as maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid. , Sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, isododecenylsuccinic acid, n-dodecylsuccinic acid,
Isododecyl succinic acid, n-octenyl succinic acid, n-
Examples thereof include octyl succinic acid, isooctenyl succinic acid, isooctyl succinic acid, and anhydrides or lower alkyl esters of these acids.

Examples of trivalent or higher carboxylic acid monomers include 1,2,4-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-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl)
Methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid and their acid anhydrides,
Lower alkyl ester and the like can be mentioned. Of these,
In particular, 1,2,4-benzenetricarboxylic acid, that is, trimellitic acid or its derivative is inexpensive and easy to control the reaction, and thus is preferably used.

In the present invention, these dihydric alcohol monomer, trivalent or higher polyhydric alcohol monomer, divalent carboxylic acid monomer and trivalent or higher carboxylic acid monomer are each used alone. Or a plurality of monomers can be used in combination. However, in the present invention, it is preferable to use at least one of a trivalent or higher valent alcohol monomer and a trivalent or higher carboxylic acid monomer in order to satisfy the thermal characteristics required for fixing.

Such polyester resin can be synthesized by a generally known method. Specifically, the reaction temperature is 170-
The reaction may be carried out at 250 ° C. and a reaction pressure of 5 mmHg to atmospheric pressure (the optimum temperature and pressure are determined by the reactivity of the monomer), and the reaction may be terminated when the above-mentioned predetermined physical properties are reached.

Further, as the binder resin, polyamide, polyester polyamide resin, etc., which are compatible with the above polyester resin, can be mixed in an appropriate amount and used.

The main component of the binder resin of the second embodiment is a resin obtained by carrying out addition polymerization and polycondensation in the same reaction vessel. For example, blending both raw material monomers of addition polymerization and polycondensation , Addition polymerization and polycondensation can be carried out in parallel. The raw material monomers and the like will be described below. In the second aspect of the present invention, when a vinyl-based resin is obtained by addition polymerization, the following vinyl-based monomers, if necessary, a crosslinking agent and a polymerization initiator such as a peroxide or an azo compound are used.

Typical monomers used to form the vinyl resin include, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene,
Styrene or styrene derivatives such as α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-chlorostyrene, vinylnaphthalene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene; Vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate,
Vinyl esters such as vinyl formate and vinyl caproate;
For example, acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, amyl acrylate, cyclohexyl acrylate, n-acrylate. Octyl, isooctyl acrylate, decyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methoxyethyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, acrylic acid 2
-Chloroethyl, phenyl acrylate, α-methyl chloroacrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate. , Amyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, decyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, methoxyethyl methacrylate, 2-hydroxyethyl methacrylate, methacryl Ethylenic monocarboxylic acids such as glycidyl acid salt, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and their esters; For example, ethylenic monocarboxylic acid substitution products such as acrylonitrile, methacrylonitrile, and acrylamide; for example, ethylenic dicarboxylic acids such as dimethyl maleate and substitution products thereof; vinyl ketones such as vinyl methyl ketone; vinyl ethers such as vinyl methyl ether. Vinylidene halides such as vinylidene chloride; for example N-vinylpyrrole, N-
Examples thereof include N-vinyl compounds such as vinylpyrrolidone. Of these, a styrene derivative or a (meth) acrylic acid ester is preferable.

When a crosslinking agent is added, for example, divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-
Butylene glycol dimethacrylate, 1,6-hexylene glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) propane, 2 General crosslinking such as 2,2'-bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, dibromoneopentyl glycol dimethacrylate, diallyl phthalate Appropriate agent (2 if necessary
A combination of two or more species can be used. Divinylbenzene and polyethylene glycol dimethacrylate are preferably used.

The amount of these crosslinking agents used is 0.001 to 15% by weight, preferably 0.1 to 15% by weight, based on the vinyl-polymerizable monomer.
It is recommended to use ~ 10% by weight. When the amount of these cross-linking agents used is more than 15% by weight, the toner obtained is less likely to be melted by heat, resulting in poor heat fixing property or heat pressure fixing property. When the amount used is less than 0.001% by weight, it is difficult to prevent the offset phenomenon in which a part of the toner adheres to the roller surface without being completely fixed to the paper and is transferred to the next paper during thermal pressure fixing. Furthermore, the amount of these cross-linking agents used is preferably 0.001 to 15% by weight, more preferably 0.1 to 10% by weight, based on the polymerizable monomer.

The polymerization initiator used for producing the vinyl resin is, for example, 2,2'-azobis (2,4-
Dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-
Dimethyl valeronitrile, other azo or diazo polymerization initiators, or benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxy carbonate, cumene hydroperoxide, 2,4-
Examples thereof include peroxide type polymerization initiators such as dichlorobenzoyl peroxide, lauroyl peroxide and dicumyl peroxide. For the purpose of controlling the molecular weight and molecular weight distribution of the polymer, the reaction time or the like, two or more kinds of polymerization initiators may be mixed and used. The amount of the polymerization initiator used is 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerized monomer.

In the second embodiment, when a polyester is obtained by polycondensation, alcohol and an acid component are used as raw material monomers. That is, as in the first aspect, a raw material monomer is a divalent or trivalent or more alcohol and a carboxylic acid, or a carboxylic acid anhydride or a carboxylic acid ester. Here, as the divalent or trivalent or higher valent alcohol component and the divalent or trivalent or higher valent acid component, the same ones as those in the first aspect can be mentioned.

As the raw material monomer for forming the amide component in the polyester polyamide or polyamide obtained by polycondensation, for example, ethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, iminobispropylamine, phenylenediamine, xylylenediamine. , Polyamines such as triethylenetetramine, aminocarboxylic acids such as 6-aminocaproic acid and ε-caprolactam, and amino alcohols such as propanolamine.

In the present invention, in order to obtain a resin in which a condensation polymerization resin and an addition polymerization resin are chemically bound, a compound capable of reacting with any of the monomers of both resins (hereinafter referred to as "both reactive compound") It is preferable to carry out the polymerization using. Such bireactive compound, in the monomer of the condensation polymerization resin and the monomer of the addition polymerization resin,
Fumaric acid, acrylic acid, methacrylic acid, citraconic acid,
Examples include compounds such as maleic acid and dimethyl fumarate. Of these, fumaric acid, acrylic acid, and methacrylic acid are preferably used. The amount of the both-reactive compound used is 0.1 to 20% by weight, preferably 0.1 to 20% by weight based on all the raw material monomers.
It is 5 to 10% by weight.

In order to produce a binder resin in which a polyester resin, a polyesteramide resin, or a polyamide resin and a vinyl resin are blended using the above raw material monomers, polyester or polyesteramide contained in a reaction vessel, or The mixture of the raw material monomer of the vinyl resin and the polymerization initiator is dropped into the raw material monomer mixture of the polyamide and premixed, and the radical polymerization reaction is first completed to complete the polymerization reaction to obtain the vinyl resin. There is a method in which the polymerization reaction to obtain polyester or polyester amide or polyamide is completed by increasing the temperature and conducting polycondensation. In this way, a binder resin in which two kinds of resins are effectively mixed and dispersed can be obtained by a method of allowing two independent reactions to proceed in parallel in a reaction container. In the above parallel reaction, the progress and completion of the two polymerization reactions do not have to be simultaneous in time, and the reaction temperature and time may be appropriately selected according to the respective reaction mechanisms to allow the reactions to proceed and complete. Good.

By such a manufacturing method, a binder resin composed of a blend of a polycondensation resin selected from the above polyester, polyesteramide or polyamide and a vinyl resin such as styrene / acrylic resin can be obtained. In this case, the mixing ratio of the polycondensation resin and the vinyl resin is preferably 10 to 90% by weight of the polycondensation resin and 90 to 10% by weight of the vinyl resin. Moreover, it is preferable that the obtained binder resin has a softening point of 95 to 160 ° C. and a glass transition temperature of 50 to 80 ° C.
The softening point and the glass transition temperature of the binder resin can be easily adjusted by adjusting the amount of the polymerization initiator or the catalyst in the raw material monomer mixture or selecting the reaction conditions.

In the present invention, the pulverizability of the binder resin can be improved by lowering the molecular weight of the resin produced in one of the reaction paths. Particularly for the vinyl-based resin portion, if the number average molecular weight is 11,000 or less, it is effective for improving the pulverizability of the binder resin. The number average molecular weight of 11,000 or less can be easily achieved by using a large amount of polymerization initiator or using a chain transfer agent.

The toner of the present invention contains the binder resin as described above, and in any of the first and second aspects, it further contains a colorant which is an essential component, and
A charge control agent and, if necessary, a fluidity improver, a release agent and the like are added.

As the charge control agent, one kind or two or more kinds of all the positively chargeable charge control agents used for the positively charged toner can be used. Specific examples include imidazole derivatives such as "PLZ-2001" and "PLZ.
-8001 "(above, manufactured by Shikoku Kasei Co., Ltd.); triphenylmethane derivative, for example," COBY BLU PR "
(Manufactured by Hoechst); quaternary ammonium compounds such as "TP-415", "TP-4040" (manufactured by Hodogaya Chemical Co., Ltd.), "Bontron P-51" (manufactured by Orient Chemical Co., Ltd.), "COPY CHARGE PX VP435" ( Hoechst), cetyltrimethylammonium bromide, and the like; polyamine resins such as “AFP-B” (Orient Chemical), and the like. Preferably, "TP-415"
Can be used.

It is also possible to use a main charge control agent and a charge control agent of opposite polarity in combination, and the amount of the charge control agent of the opposite chargeability is set to 1/2 or less of the amount of the charge control agent of the main chargeability. If you do 5
Even if development is continuously performed on ten thousand or more sheets, the density does not decrease and a good visible image can be obtained. These charge control agents are contained in the binder resin in an amount of 0.1 to 8.0% by weight, particularly 0.2.
It is preferable to add the compound in an amount of ˜5.0 wt%.

As the colorant, a pigment such as a chromatic dye or carbon black that develops black, or a grafted carbon black in which the surface of carbon black is coated with a resin is used, and all known pigments can be used. It is not particularly limited. In addition to black, there are three primary colors of yellow, magenta, and cyan. For example, yellow has C.I. I. Solvent Yellow 21, C.I. I. Solvent Yellow 77, C.I. I. Pigment Yellow 12, C.I.
I. Disperse Yellow 164 and the like can be mentioned. C. for magenta. I. Solvent Red 49, C.I. I. Solvent Red 128, C.I. I. Pigment Red 13,
C. I. Pigment Red 48.2, C.I. I. Disperse Red 11 and the like can be mentioned. Cyan is C.I. I. Solvent Blue 21, C.I. I. Solvent Blue 94,
C. I. Pigment Blue 15.3 and the like.

These colorants are preferably added in an amount of 0.01 to 20% by weight, particularly 1 to 10% by weight, based on the total amount of the toner.

In the toner of the present invention, if necessary,
A fluidity improver other than silica, a cleaning improver, etc. can be used. As the fluidity improver, for example, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite,
Diatomaceous earth, chromium oxide, cerium dioxide, red iron oxide,
Examples thereof include antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide and silicon nitride.

As the cleaning property improver, fatty acids and / or metal salts thereof, fine particles of fluorine type high molecular weight particles, silicone resin fine particles and the like can be used. The fluidity improver and the cleaning property improver are preferably added in the range of 0.01 to 1.0% by weight with respect to the toner.

A releasing agent may be used in the toner of the present invention, if necessary, for the purpose of improving offset resistance in heat roller fixing. Examples of the release agent include fatty acids and / or metal salts thereof, polyolefins, fatty acid esters, partially saponified fatty acid esters, higher alcohols, paraffin waxes, amide waxes, polyhydric alcohol esters, silicon varnishes, aliphatic fluorocarbons, Any one of offset preventive agents such as silicone oil
You may contain a seed or more.

Various additives other than the above may be added to the toner of the present invention. For example, as an additive for adjusting the developing property, for example, fine particle powder of a polymer of methyl methacrylate is used. Yes, even toning,
A small amount of carbon black can be used for resistance adjustment or the like.

As the method for producing the toner of the present invention, conventionally known production methods such as a kneading and pulverizing method, a spray dry method and a polymerization method can be used. For example, as a general example, first, a binder resin, a colorant, a wax, a charge control agent, etc. are uniformly dispersed and mixed in a known mixer, and then the mixture is closed kneader or a single-screw or twin-screw extruder. It may be melt-kneaded with a solvent or the like, cooled, pulverized, and classified. In recent years, a single-screw or twin-screw extruder is mainly used because of its superiority such as continuous production of kneaders. For example, KTK type twin-screw extruder manufactured by Kobe Steel, TEM type extruder manufactured by Toshiba Machine Co., Ltd.・ C-K twin screw extruder, Ikegai Iron Works PCM twin screw extruder,
A co-kneader manufactured by Bus Co. is preferably used.

The average particle size of the toner thus obtained is usually 20 μm or less, and the average particle size is 7 to 1
5 μm is preferable. The average particle size here is a volume average particle size.

The positively chargeable toner of the present invention is characterized in that the above-mentioned silica fine particles adhere to the surface of the toner obtained as described above. As a treatment method for such adhesion, the classified toner and silica fine particles may be stirred and mixed by a high speed stirrer such as a super mixer or a Henschel mixer, and if necessary, a toner for start developer and a toner for replenishment may be added. The type and amount of silica fine particles used may be different. Further, the mixing conditions such as the number of rotations for stirring and the mixing time may be appropriately determined in accordance with the toner performance. Further, the silica fine particles may be subjected to a crushing treatment in advance, if necessary.

The developer composition of the present invention comprises a carrier carrying the above-mentioned toner. The carrier used in the present invention is preferably a sponge called a sponge, which has a porous irregular iron powder having irregularities on the surface as a core material and whose outer surface is coated with a coating agent.

As the irregular iron powder constituting the core, ore reduced iron powder produced by reducing iron ore, mill scale reduced iron powder produced by reducing mill scale, and molten steel are allowed to flow out from the pores. Spherical atomized iron powder cooled and powdered,
Examples of the iron nitride powder obtained by nitriding thin steel pieces and crushing and denitrifying the steel pieces include those having a bulk specific gravity of 2 to 4 g / cm ³ and an average particle diameter of 50 to 200 μm, particularly 55 to 170 μm. It is also preferable to use an irregular iron powder having fine pores having a difference in roughness of each particle of 10 μm or more.

Since the iron powder carrier is oxidized by the presence of water in the air to generate Fe ₂ O ₃ (so-called rust) on the surface, it is covered with a stable oxide thin film having a relatively high resistance by forced oxidation. The electric resistance as a carrier can be adjusted by adjusting the thickness of the thin film according to the degree of this treatment.

As a coating agent for coating the outer surface of the irregularly shaped iron powder, it has been conventionally used for electrophotography for the purpose of facilitating charge control and maintaining charge stability at long run and high temperature and high humidity. All known carrier coating agents can be used.

Specific examples thereof include styrene acrylic resin, polyester resin, polyamide resin, epoxy resin, or various fluorocarbons as silicone resin, silicone acrylic resin, or fluororesin which further increases the surface lubricity. To be Specific examples of the fluorocarbon include homopolymers or copolymers of vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, tetrafluoroethylene, hexafluoropropylene and the like. More specifically, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoropropylene copolymer and the like can be mentioned. Of these, fluororesins using ethylene tetrafluoride or vinylidene fluoride as one of the monomers are preferable.

Further, the above-mentioned fluororesin can be used as a mixture with inorganic fine particles such as alumina, graphite, molybdenum disulfide, bronze, etc. in order to improve electric characteristics or wear characteristics. Firing and binding can be performed at a temperature near the melting point. Furthermore, a polyamide resin or an epoxy resin can be added to the adhesive to improve the adhesive strength of the fluororesin to the surface of the irregular iron powder and to impart durability.

As a coating method, the above resins are dispersed in a dispersion medium such as methyl ethyl ketone or tetrahydrofuran, and the carrier is immersed in this dispersion.
Alternatively, it can be obtained by spraying the dispersion medium on the surface of a carrier and subsequently thermosetting at 150 to 300 ° C. The coating amount is preferably 0.2 to 10% by weight, and more preferably 0.4 to 5% by weight, based on the weight of the carrier.

The developer composition of the present invention can be prepared by mixing the above-mentioned coated carrier with the above-mentioned toner. At this time, the mixing weight ratio of the carrier and the toner (carrier / toner) is usually 90/10 to 98/2, preferably 94/6 to 97 /.
It is 3.

[0071]

EXAMPLES The present invention will be described in more detail with reference to Examples, Comparative Examples and Test Examples, but the present invention is not limited to these Examples. FIG.
Shows the particle size distribution of the silica fine particles used in Examples and Comparative Examples.

Resin Production Example 1 Polyoxypropylene (2.2) -2,2-bis (4-
Hydroxyphenyl) propane 740 g, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 300 g, dimethyl terephthalate 466
g, isododecenyl succinic anhydride 80 g, 1,2,4-
114 g of tri-n-butylbenzenetricarboxylate was placed in a glass 2-liter four-necked flask together with an ordinary esterification catalyst, and a thermometer, a stainless steel stirring rod, a downflow condenser and a nitrogen inlet tube were attached, and in an electric heating mantle heater. 210 ° C normal pressure under nitrogen flow, 210 latter half
The reaction was allowed to proceed with stirring under reduced pressure at 0 ° C.

The obtained polyester resin has an acid value of 2.8.
The KOH mg / g, the hydroxyl value were 28.0 KOH mg / g, and the Koka type flow tester softening temperature was 138.7 ° C. Let the said resin be binder resin (1).

Resin Production Example 2 As the vinyl resin monomer, styrene 665 g, 2-
127 g of ethylhexyl acrylate and 32 g of dicumyl peroxide as a polymerization initiator are placed in a dropping funnel. 1444 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 40 g of fumaric acid, 47 g of isododecenyl succinic anhydride, 378 g of terephthalic acid, 135 g of 1,2,4-benzenetricarboxylic acid, and dibutyl 5 g of tin oxide was placed in a glass 5 liter 4-necked flask, equipped with a thermometer, a stainless stir bar, a downflow condenser and a nitrogen inlet tube, while stirring at a temperature of 160 ° C. in a nitrogen atmosphere in a mantle heater. The vinyl resin monomer and the polymerization initiator were dropped from the dropping funnel over 1 hour. 160 ° C
The mixture was aged for 2 hours while being kept at, and the temperature was raised to 230 ° C. for reaction. The degree of polymerization was traced from the softening point according to ASTM E28-67, and the reaction was terminated when the softening point reached 138 ° C.

The glass transition temperature (Tg) of the obtained resin was 62.5 ° C. with one peak and the acid value was 5.5 KOHmg.
/ G. Let the said resin be binder resin (2).

Example 1 Binder Resin (1) 87 parts by weight Carbon Black "Regal 330R" (manufactured by Cabot) 7 parts by weight Positively chargeable charge control agent "Bontron N-07" (manufactured by Orient Chemical Co.) 2 parts by weight Positively chargeable charge control agent "TP-415" (manufactured by Hodogaya Chemical Co., Ltd.) 1 part by weight Zinc stearate "SZ" (manufactured by NOF CORPORATION) 3 parts by weight After thoroughly mixing the above raw materials with a Henschel mixer, the barrel Melt-kneading with a twin-screw extruder equipped with a cooling device, cooling,
After coarsely crushing, it was crushed with a jet mill and further classified with an air classifier to obtain an untreated toner 1 having an average particle size of 11 μm.

Next, using this untreated toner, silica fine particles having a number average particle size of primary particles of 40 nm and a frequency of 5% of particles having a particle size of 20 nm or less in its particle size distribution (Nippon Aerosil Co., Ltd.). Manufactured by R-809, a hydrophobized product), and subjected to surface treatment as follows to obtain a positively chargeable toner 1 of the present invention. That is, the surface treatment of the toner with the silica fine particles is performed by treating the untreated toner 1 with 10
To 100 g, 3.0 g of silica fine particles were added and mixed and attached using a Henschel mixer.

Example 2 A positively chargeable toner 2 of the present invention was obtained in the same manner as in Example 1, except that the amount of the silica fine particles used was changed from 3.0 g to 6.0 g.

Example 3 In the same manner as in Example 1 except that the binder resin (1) was changed to the binder resin (2), a positively chargeable toner 3 of the present invention was obtained.

Comparative Example 1 In Example 1, the silica fine particles were silica fine particles in which the number average particle size of primary particles was 16 nm and the frequency of particles having a particle size of 20 nm or less in the particle size distribution was 90% (Nippon Aerosil). Comparative Toner 1 was obtained in the same manner as in Example 1 except that the product was changed to R-972, a product manufactured by Hydrophobization Co., Ltd.).

Comparative Example 2 In Example 1, the silica fine particles were silica fine particles in which the number average particle size of primary particles was 12 nm and the frequency of particles having a particle size of 20 nm or less in the particle size distribution was 97% (Japan Aerosil). Comparative Toner 2 was obtained in the same manner as in Example 1 except that the product was changed to R-974, a hydrophobized product manufactured by K.K.

Comparative Example 3 In Example 1, the silica fine particles had a number average particle size of primary particles of 7 nm and a particle size of 2 in the particle size distribution.
Comparative Toner 3 was obtained in the same manner as in Example 1 except that the silica fine particles (R-976, manufactured by Nippon Aerosil Co., Ltd.) having a frequency of particles of 0 nm or less of 98% were used.

Comparative Example 4 In Example 1, as the silica fine particles, silica fine particles having a number average particle diameter of primary particles of 40 nm and a frequency of 5% of particles having a particle diameter of 20 nm or less in its particle size distribution (Japan Aerosil (Manufactured by R-809, hydrophobized product)
Is 3.0 g, and the number average particle size of primary particles is 16 nm, and the frequency of particles having a particle size of 20 nm or less in the particle size distribution is 90% (manufactured by Nippon Aerosil Co., Ltd., R-972, hydrophobized). Comparative toner 4 was obtained in the same manner as in Example 1 except that the surface treatment was performed using 0.3 g of the treated product). In this case, the total number average particle size of the two types of silica fine particles was 30 nm, and the frequency of particles having a particle size of 20 nm or less in the particle size distribution was 40%.

Comparative Example 5 In Example 1, the silica fine particles were silica fine particles in which the number average particle diameter of the primary particles was 12 nm and the frequency of particles having a particle diameter of 20 nm or less in the particle size distribution was 98% (Nippon Aerosil). Comparative Toner 5 was obtained in the same manner as in Example 1 except that RA-200H, manufactured by Mfg. Co., Hydrophobized treatment with aminosilane and hexamethyldisilazane, positively charged) was used.

Coated Carrier Production Example 1 Sponge Iron Powder Copy Powder with Average Particle Diameter 160 μm
er CS105-175 (manufactured by Hoganas AB) to 1000 parts by weight, vinylidene fluoride-tetrafluoroethylene copolymer [VT50 (manufactured by Daikin Industries, Ltd.), copolymerization molar ratio 80:20] 50 parts by weight and epoxy resin [Epicoat 1001 (manufactured by Mitsubishi Petrochemical Co., Ltd.)] 20
A dispersion was prepared by dispersing 1000 parts by weight of methyl ethyl ketone in 1000 parts by weight, and using a rolling fluidized bed coating device, a part of the conductive graphite-filled sponge iron powder was left as a coat layer with respect to 1000 parts by weight. After spray coating on the surface and further drying, 2 in an electric furnace
Heat treatment was performed at 00 ° C. for 30 minutes to obtain coated carrier 1.

Test Example 1 A positively charged developer was prepared by mixing 100 parts by weight of the coated carrier 1 with 3 parts by weight of the toner obtained in the examples or comparative examples. These developers were subjected to a fixing property test by a reversal phenomenon using a remodeling machine of an OPC belt-equipped copying machine (Fuji Xerox, FX1075).
A long-run test of 1 million sheets was performed at 3 ° C. and 50% RH), and the developer charge amount, carrier resistance, image, and fixability were evaluated by the following methods.

(1) Evaluation of charge amount: The device used for evaluation of the charge amount is a blow-off type charge amount measuring device, and this device is a specific charge measuring device equipped with a Faraday cage, a capacitor and an electrometer. . Measuring method is 3
W (g) (about 3.0 g) of the developer taken out from the developing tank was put into a brass measuring cell equipped with a 25 mesh (a size that does not allow carrier particles to pass) stainless steel mesh. Next, suction was performed through the suction holes at a pressure indicating a flow meter of 3 liters / minute for 90 seconds to remove only the toner from the cells. The voltage of the electrometer 90 seconds after the start of suction is set to V (volt). If the electric capacity of the capacitor is C (μF), the specific charge of this toner is Q / m.
Is calculated by the following formula. Q / m (μC / g) = C × V / m Here, m is the weight of the toner contained in the developer in W (g), and the weight of the toner in the developer is T (g). When the weight of the developer is D (g), the toner concentration of the sample is expressed as T / D × 100 (%), and m is calculated by the following formula. m (g) = W × (T / D)

(2) Evaluation of carrier resistance: When the charge amount was measured in (1), the carrier remaining on the stainless steel mesh of the blow-off type charge amount measuring device was measured by a dynamic carrier resistance measuring device (C-meter Epping GmbH). 1 cc with a measuring spoon attached to the cell (made by the company), magnetic force 630 gauss, pre-stirring 63 seconds, applied voltage 12
Dynamic carrier resistance was measured using a V, 10,000 pF capacitor.

(3) Evaluation of image: Evaluation was carried out by the following methods with respect to development density and background stain. The image density is the Macbeth reflection densitometer RD-914 (macbeth pro
It was evaluated by a measurement value by ces Measurements. For background stains, whiteness measurement color difference meter Z-1
The whiteness of the surface of the unused paper and the non-image area of the paper after development was measured by 001 Dp (manufactured by Nippon Denshoku Industries Co., Ltd.) and evaluated by the relative comparison value obtained by subtracting the latter from the former.

(4) Evaluation of fixing property: The fixing part of the above copying machine was subjected to image formation without applying silicone oil and was modified so that the roller temperature could be varied.
By controlling the temperature to ˜240 ° C., the minimum fixing temperature of the image and the offset property were evaluated. Here, the minimum fixing temperature is a reflection densitometer of Macbeth Inc. before and after rubbing 5 times on the image fixed through a fixing machine, placing a load of 500 g on a sand eraser with a bottom surface of 15 mm × 7.5 mm, and rubbing. The optical reflection density is measured according to the following, and it means the temperature of the fixing roller when the fixing rate exceeds 70% according to the following definition. Fixing rate (%) = (image density after rubbing / image density before rubbing) × 100 For toners 1 to comparative toner 5, a fixing temperature of 180 ° C. or lower, which is the target minimum fixing temperature, should be secured. Moreover, no offset occurred even at 240 ° C.

Table 1 shows the test results of the above (1) to (3). The test results for the evaluation of the fixability are excluded from the table because the offset phenomenon has not occurred in all toners.

[0092]

[Table 1]

As is clear from the results shown in Table 1, when the positively chargeable toners of Examples 1 to 3 are used, the toner charge amount and the carrier resistance are maintained at a substantially constant value for a long period of time. It was possible to maintain high image quality. On the other hand, in Comparative Examples 1 to 3 in which the number average particle diameter of primary particles of silica is less than 30 nm, a decrease in the charge amount of the toner, an increase in carrier resistance, a background stain and a decrease in image density were observed from the initial stage. . Further, even in Comparative Example 4 in which the number average particle size of silica is 30 nm or more and the frequency of particles having a particle size of 20 nm or less in the particle size distribution exceeds 20%, the charge amount of the toner also decreases. An increase in carrier resistance, scumming from the beginning, and a decrease in image density were observed. Also in Comparative Example 5 using silica having a positive chargeability, when the number average particle size of the primary particles is smaller than 30 nm, the initial performance is satisfactory, but the charge amount decreases and the carrier resistance increases as the running length increases. As a result, the image density decreased and the background stain increased.

[0094]

The positively chargeable toner and developer composition of the present invention maintain the charge amount and carrier resistance of the toner at constant values for a long period of time, and enhance the cleaning property of the toner on the surface of the photoreceptor. As a result, high image quality can be maintained. Further, since this effect does not depend on the kind of the binder resin or the like, by appropriately selecting the binder resin or the carrier,
It is possible to obtain a positively chargeable toner and a developer composition that have good low-temperature fixability, environmental stability, long life, and the like.

[Brief description of drawings]

FIG. 1 shows a particle size distribution of silica fine particles used in Examples and Comparative Examples.

Claims (8)

[Claims] 1. A positively chargeable toner containing at least a binder resin and a colorant, wherein the number average particle size of primary particles is 30 to 100 nm, and the frequency of particles having a particle size of 20 nm or less in the particle size distribution. Of 20% or less is adhered to the surface of the toner, and the toner is positively charged. 2. The toner 100 has a deposition amount of silica fine particles.
It is 0.1 to 3.0 parts by weight with respect to parts by weight.
The positively chargeable toner described above. 3. The positively chargeable toner according to claim 1, wherein the silica fine particles are silica which has been subjected to a hydrophobic surface treatment. 4. The polyester resin whose main component of the binder resin is a polyester having a softening point of 95 to 160 ° C. by a Koka type flow tester and a glass transition temperature of 50 to 80 ° C. by DSC. 3. The positively chargeable toner according to any one of 3 above. 5. The resin as a main component of the binder resin is a resin obtained by carrying out addition polymerization and polycondensation in the same reaction vessel, and the addition polymerization is to obtain a vinyl resin by radical polymerization, and The positively chargeable toner according to claim 1, wherein the polycondensation is to obtain polyester, polyesteramide or polyamide. 6. A developer composition comprising the positively chargeable toner according to claim 1 and a carrier capable of carrying the toner. 7. The developer composition according to claim 6, wherein the carrier is a porous amorphous iron powder having irregularities on the surface. 8. The average particle size of the irregular iron powder is 50 to 200 μm.
8. The developer composition according to claim 7, wherein the developer composition is m, and the difference between the uneven portions is 10 μm or more.