JPH05281785A - Production of toner for dry processing, electrophotographic developer and image forming method - Google Patents

Abstract

PURPOSE:To obtain a long life and high-fineness image and further, to obtain excellent fixability and board offset resistance by adding specific coloring agents to a specific resin and melting and kneading the resin until its gel-component attains a specific value. CONSTITUTION:This process for production of the toner for dry processing consists in adding carbon black having >=200m<2>/g specific surface area and magnetite having <=6m<2>/g as the coloring agents to the vinyl resin having 20 to 50wt.% gel-component, then melting and kneading the resin until the gel- component attains <=10wt.%. The resulted toner has the excellent flow property and is further resistant to staining with a carrier. The long-life developer is thus obtainable. The average grain size of the toner to be used is preferably 5 to 12mum, more particularly preferably 6 to 10mum. The produced toner for dry processing and the electrophotographic developer formed by using such toner are excellent in the broad offset resistance, line image printing density and plane image printing density. The high-fineness image which fogs less and has extremely high resolution is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a two-component dry toner useful for developing an electrostatic image formed by electrophotography, a developer for electrophotography and an image forming method using the same.

[0002]

2. Description of the Related Art In electrophotography, after uniformly charging a photoconductor, a photoimage based on an original image is exposed to the photoconductor to eliminate or reduce the electric charge in a light-irradiated portion, An electrostatic latent image based on the original image is formed on the top, and after that,
It is well known that a so-called two-component developer, which is composed of carrier particles and toner particles, is used to obtain a visualized copy. In this two-component developer, fine toner particles are held on the surface of a relatively large carrier particle by the electrostatic force generated by the friction between the particles, and when the electrostatic latent image is approached, the electrostatic latent image is generated. The attraction force of the electric field formed by the toner particles in the direction of the latent image against the toner particles overcomes the binding force between the toner particles and the carrier particles, and the toner particles are attracted and adhered to the electrostatic latent image to form the electrostatic latent image. It is what is visualized. Then, the developer is repeatedly used while replenishing the toner consumed by the development.

Further, in recent years, S has been used as a photoreceptor for an electrostatic image.
Photoconductors having organic photoconductive layers in place of inorganic photoconductive layers such as e, Se-Te, As ₂ Se ₃ (hereinafter referred to as organic photoconductors) have been used in copying machines and printers. The organic photoconductor has a lower surface hardness than the inorganic photoconductor, and is more likely to be damaged or rubbed by a developer, especially a carrier.

The function of the conventional laser beam printer using the electrophotographic method is to output a line image of alphabets, numbers, kanji, or the like. In recent years, in addition to line images, the need to output surface images such as barcodes and solid black has increased. In surface image printing such as bar code printing, the electric flux density at the central portion of the latent image pattern formed on the surface of the photoconductor drum is much lower than that at the edge portion. Therefore, during the developing process, the toner is concentrated on the edge portion of the pattern and hardly adheres to the central portion of the pattern, which is a defect in the printing process.

Recently, a digital type copying machine has been developed, and the demand for high-definition image output of the copying machine, laser beam printer, etc. has become stronger. For example, until now, most printers have 240 dpi or 300
Although it was dpi, it will be 480 dpi in the future and 6
It is expected that high-definition image output of 00 dpi will become the mainstream.

[0006]

In order to solve these drawbacks and output a surface image, a bias voltage is applied,
A method for controlling printing has been proposed. This bias voltage is a static voltage applied between the surface of the photoconductor drum and the magnetic brush so that the magnetic brush side has a polarity opposite to that of the voltage of the toner. The bias voltage causes the toner particles to move to a portion of the surface of the photosensitive drum having a low electric flux density, and as a result, a uniform surface image can be obtained. However, when the bias voltage is very strong, the toner may adhere to a portion other than the latent image formed on the photosensitive drum, and a phenomenon called so-called fog may occur.

The bias voltage method as described above is particularly effective in the case of a developer using a carrier having a low electric resistance. When a carrier having a high electric resistance is used, the voltage drop at the magnetic brush portion is large and the voltage difference between the magnetic brush tip and the surface of the photoconductor is low, so that an effective bias voltage application effect cannot be obtained. When a carrier having an extremely low electric resistance is used, the voltage drop in the magnetic brush portion is small and it is preferable in terms of the bias voltage effect, but it is not preferable from the standpoint of chargeability with the toner, that is, charge imparting to the toner.

When the developer is used for a certain period of time, a phenomenon called so-called spent, in which the toner is fused to the surface of the carrier, occurs, resulting in an increase in the resistance of the carrier. As a method of reducing this spent amount, a material on which toner is difficult to adhere to the carrier surface, for example, a method of coating a fluororesin, a polybutadiene resin, a silicon resin, etc. is adopted, but the electric resistance of the coating material itself is high,
Not suitable for lowering carrier resistance.

On the other hand, in order to improve the quality of line drawing printing and the output of surface printing, a method of using a carrier having a large specific surface area to increase the toner concentration in the developer is also being studied.
However, in this method, there are problems such as toner scattering and carrier adhesion to the photoconductor.
Further, it is difficult to maintain the print quality of the plane image for a long time.

Further, in order to support high-definition image output,
It is conceivable that the toner has a smaller particle size or the carrier has a smaller particle size.
For example, there are problems such as crushing efficiency and classification accuracy, and in terms of characteristics, there are problems such as fluidity, charging uniformity, toner scattering, developer deterioration, cleaning properties, transfer properties, and fixing properties.
In addition, when the particle size of the carrier is reduced, there is a problem that the carrier adheres to the surface of the photoreceptor.

Further, due to the recent cost increase caused by the soaring price of oil, it has been studied to use a common toner, that is, to use the same toner from low-speed machines to medium-high speed machines. This requires the toner to have better fixability and wider offset resistance.

Therefore, various binder resins for toner have been studied. It is generally known that when a resin containing a gel component is used as a binder resin, it has excellent offset resistance, particularly high temperature offset resistance. However, a resin having a gel content is difficult to melt-knead, and dispersion of pigments such as carbon black and various additives is insufficient, and thus the obtained dry toner is inferior in characteristics such as fog and resolution. This tendency is particularly large when a toner having a small particle diameter is used.

The present invention solves such problems, a method for producing a dry toner capable of obtaining a high-definition image with a long life, excellent fixing properties and a wide range of offset resistance, and a developer for electrophotography. And an image forming method.

[0014]

The present invention has a gel content of 20.
Carbon black having a specific surface area of 200 m ² / g or more and magnetite having a specific surface area of 6 m ² / g or less are added as a colorant to ˜50 wt% of vinyl resin, and the gel content is 1
A method for producing a dry toner, characterized by melt-kneading until 0% by weight or less, an electrophotographic developer containing the dry toner obtained by the production method and a carrier, and the developer. And an image forming method.

In the method for producing the dry toner of the present invention, first, a vinyl resin having a gel content of 20 to 50% by weight, preferably styrene such as styrene-acrylic acid ester copolymer or styrene-methacrylic acid ester copolymer. -Manufacturing acrylic resin as a binder resin.

Examples of the styrene-acrylic resin base monomer include the following. Styrene and its derivatives such as styrene, α-methylstyrene, p-methylstyrene, p-t-butylstyrene, p-chlorostyrene, and hydroxystyrene, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylic acid. Butyl, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, glycidyl methacrylate, methoxyethyl methacrylate, propoxyethyl methacrylate, methacrylic acid Butoxyethyl, methoxydiethylene glycol methacrylate, ethoxydiethylene glycol methacrylate, methoxyethylene glycol methacrylate, butoxide Ethylene glycol, methoxydipropylene glycol methacrylate, phenoxyethyl methacrylate, phenoxydiethylene glycol methacrylate, phenoxytetraethylene glycol methacrylate, benzyl methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, dicyclopentenyl methacrylate, Dicyclopentenyloxyethyl methacrylate, N-vinyl-2-pyrrolidone methacrylate, methacrylonitrile, methacrylamide, N
-Methylol methacrylamide, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, 2-hydroxy-3-phenyloxypropyl methacrylate, phthalimidoethyl methacrylate, phthalimidopropyl methacrylate, morpholinoethyl methacrylate, methacryl Acid morpholinopropyl, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diacetone methacrylamide, acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, butyl acrylate ,
Octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, glycidyl acrylate, methoxyethyl acrylate, propoxyethyl acrylate, butoxyethyl acrylate,
Methoxydiethylene glycol acrylate, ethoxydiethylene glycol acrylate, methoxyethylene glycol acrylate, butoxytriethylene glycol acrylate, methoxydipropylene glycol acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxytetraethylene glycol acrylate, benzyl acrylate , Cyclohexyl acrylate, tetrahydrofurfuryl acrylate,
Dicyclopentenyl acrylate, dicyclopentenyl oxyethyl acrylate, N-vinyl-2-pyrrolidone acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxy-3-phenyloxypropyl acrylate ,
Glycidyl acrylate, acrylonitrile, acrylamide, N-methylol acrylamide, diacetone acrylamide, vinyl pyridine, phthalimidoethyl acrylate, phthalimidopropyl acrylate, morpholinoethyl acrylate, morpholinopropyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate , A reaction product of divinylbenzene, glycol and methacrylic acid or acrylic acid, such as ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, diethylene glycol dimethac Rate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, tripropylene glycol dimethacrylate, hydroxypivalic acid neopentyl glycol ester dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol Tetramethacrylate, trismethacryloxyethyl phosphate, bis (methacryloyloxyethyl)
Hydroxyethyl isocyanurate, tris (methacryloyloxyethyl) isocyanurate, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6
-Hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene diacrylate, hydroxypentalic acid neopentyl glycol diacrylate, trimethylolethane triacrylate, tri Methylolpropane triacrylate,
Pentaerythritto triacrylate, pentaerythritto tetraacrylate, trisacryloxyethyl phosphate, bis (methacryloyloxyethyl) hydroxyethyl isocyanurate, tris (methacryloyloxyethyl) isocyanurate, glycidyl methacrylate and methacrylic acid or acrylic acid half Esterification products, half-esterification products of bisphenol type epoxy resin and methacrylic acid or acrylic acid, and half-esterification products of glycidyl acrylate and methacrylic acid or acrylic acid. Among these monomers, preferable ones having one vinyl group in one molecule include styrene, styrene derivatives, methacrylic acid esters and acrylic acid esters.

As the polymerization initiator used in the polymerization, acetyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and perdicarbonic acid are used. Diisopropyl, di-2-ethyl-hexyl perdicarbonate, acetylcyclohexanesulfonyl peroxide, peroxide t
ert-butyl, tert-butyl perisobutyrate, azobisisobutyronitrile, 2,2'-azobis-2,4-
Dimethylvaleronitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, tert-butyl per-2-ethylhexanoate, tert-perbenzoic acid
A known polymerization initiator such as butyl is used. These are preferably used in an amount of 0.1 to 15% by weight based on the total amount of monomers.

The vinyl resin having a gel content of 20 to 50% by weight can be produced by a suspension polymerization method using water as a dispersion medium, an emulsion polymerization method or the like. Suspension polymerization is preferred because post-treatment such as resin drying is easy. The gel content is adjusted by the polyfunctional monomer that is copolymerized. As the polyfunctional monomer, the above-mentioned divinylbenzene, ethylene glycol diacrylate, trimethylolpropane triacrylate, etc. can be used, but it is preferable to use divinylbenzene because of its copolymerizability and the like. In the suspension polymerization method, the gel content can be adjusted by dividing the polymerization process. For example, suspension polymerization is performed using a copolymerizable monomer mixture containing no polyfunctional monomer in the first stage, and then a copolymerizable monomer mixture containing a polyfunctional monomer is added in the second stage to complete the polymerization. To do. This method is a preferable method because the gel content can be controlled easily and freely to some extent.

When the gel content of the vinyl resin is less than 20% by weight, the wide offset resistance of the present invention cannot be obtained. When the gel content exceeds 50% by weight, melt-kneading becomes difficult and a large amount of energy is required. Incidentally, the measurement of the gel content, the solvent is methyl ethyl ketone,
Measure using a Soxhlet extractor.

Next, as a colorant, carbon black having a specific surface area of 200 m ² / g or more, magnetite having a specific surface area of 6 m ² / g or less, and, if necessary, a nigrosine dye, an azo dye, are added to the vinyl resin. Salicylic acid derivatives, charge control agents such as metal salts thereof, and other various additives such as fixing property improvers such as polypropylene, polyethylene and carnauba wax are mixed and mixed in a commonly used amount, and a hot roll mill, a co-kneader, etc. Melt and knead well with a mixer to adjust the gel content to 10% by weight or less.
This makes it possible to improve the fixability. Also,
Since the pulverizability is also improved, it becomes easy to obtain a desired particle size, and even a toner having an average particle size of 10 μm or less can be obtained in a high yield. If the dry toner obtained in this step has a gel content of more than 10% by weight, the pulverizability of the toner is particularly poor, and the yield is extremely poor when the toner is 10 μm or less. Furthermore, the image quality and fixability are also poor.

The specific surface area that can be used in the present invention is 200 m ^2.
Carbon pearls (BLACK PEARLS) 1 manufactured by Cabot Co., Ltd.
400, Black Pearls 1300, Black Pearls 1100, Black Pearls 1000, Black Pearls 900, Black Pearls 880, Black Pearls 800, Black Pearls 700, Monarch 1400, Monarch 130
0, Monarch 1100, Monarch 1000, Monarch 900, Monarch 880, Monarch 800, Monarch 700, VULCAN XC72 and Vulcan XC72R, # 600 manufactured by Mitsubishi Kasei.
Colombia Carbon Super Spectra (SU
PER SPECTRA), Royal Spectra (RO
YAL SPECTRA), Neo Spectra Mark I
(NEO SPECTRA MARK I), NEO SPECTRA MARK II, NEO SPECTRA AG, NEO SPECTRA TA, SUPERBA No. 9
99, PEERLESS, Peerless Mark II and CONDUCTEX S
C, Degussa's special black (SPECIAL
BLACK) 5, special black 6, color black (COLOR BLACK) FW1, color black FW2, color black FW200, PRINTEX 95, PRINTEX 9
0, Printex 85, Printex 80, Printex EX 2 and Printex L6 can be used. By using such a carbon black having a large specific surface area in the toner of the present invention, the resistance of the toner can be controlled to be low, and the image quality, especially the image uniformity and the image density are excellent. When carbon black having a specific surface area of less than 200 m ² / g is used, not only the toner has a high resistance and the image density does not appear, but also when it is combined with the vinyl resin containing the gel component of the present invention, remarkable fog occurs. .. The upper limit of the specific surface area is not particularly limited, but is generally 1000 m ² / g or less. Specific surface area is 200
The blending amount of carbon black of m ² / g or more is preferably 5 to 15 parts by weight, and 7 to 10 parts by weight with respect to 100 parts by weight of all toner components.

The specific surface area that can be used in the present invention is 6 m ² / g
As the magnetite below, EPT-10 manufactured by Toda Kogyo Co., Ltd.
00, MAT-210, MAT-222, Mitsui Metal Industry MG-WL, MG-WM, MG-LZ, MG-ZF,
Etc. can be used. When the specific surface area exceeds 6 m ² / g, the effect of suppressing toner scattering and the stability of image density are poor. The blending amount of magnetite having a specific surface area of 6 m ² / g or less is preferably 0.5 to 5 parts by weight based on 100 parts by weight of all toner components in terms of moisture resistance and fluidity. A particularly preferable blending amount is 1 to 3 parts by weight. Specific surface area is 1
6 m ² / g is preferred.

The kneaded product obtained above can be cooled, pulverized and classified by a usual method to obtain a dry toner.
Further, these toners may be used by externally adding a fluidity improving agent such as hydrophobic silica, alumina, molybdenum disulfide, or titanium oxide, a cleaning improving agent such as zinc stearate, magnesium stearate, or zinc laurate. You can also

The toner obtained by the present invention is excellent in fluidity of the toner, is less likely to contaminate the carrier, and can provide a developer having a long life. The average particle size of the toner used in the present invention is preferably 5 to 12 μm, particularly preferably 6 to 10 μm. Average particle size of toner is 5μ
When it is less than m, the resolution is excellent, but the fluidity of the toner is inferior, there is a problem that the toner is difficult to be supplied from the toner hopper to the developer, or the fluidity of the developer is deteriorated. Fog may occur. On the other hand, when the average particle size exceeds 12 μm, the resolution is poor. In recent years, it has been important to control the particle size of toner for high-definition images. Especially when outputting a high definition image of 600 dpi or more,
It is necessary to reduce the toner particle size. The preferred particle size range for 600 dpi is 6-8 μm.

The particle size of the toner can be measured by a usual method, but if the amount of the sample is small, the measuring time is short, the repeatability is excellent, etc., the particle size is measured by using a Coulter counter (manufactured by Coulter Co.). good.

The dry toner thus obtained is mixed with a carrier to obtain the electrophotographic developer of the present invention. The toner concentration in the developer is a normal amount (1 to 10 relative to the total amount of the developer).
% By weight). As the carrier used in the present invention, a ferrite-based carrier having a particle size of 30 to 300 μm, such as iron ferrite, copper zinc ferrite, or nickel zinc ferrite, is preferably used. If the average particle size of the carrier is less than 30 μm, the carrier tends to adhere to the surface of the photoconductor, causing damage to the photoconductor and deterioration of image quality. On the other hand, when the average particle size exceeds 300 μm, the amount of toner that can be held on the carrier surface decreases,
Image quality tends to fluctuate during continuous printing.
Further, particularly when an organic photoreceptor is used as the photoreceptor for electrostatic image, it is preferable to use a ferrite carrier because damage to the photoreceptor is small.

The carrier used in the present invention is particularly preferably coated with a resin. Examples of the coating resin include styrene-acrylic resin, silicone resin, fluorine-containing resin, polyester resin, modified amino resin, and the like, and these can be used alone or in combination of two or more. Further, depending on the case, various additives, such as carbon black, a charge control substance such as a nigrosine derivative, alumina, silica, etc., may be added to various resins. By coating the ferrite-based carrier with a resin, charging property, moisture resistance and durability are significantly improved.

As a coating method, there is a method in which various resins are dissolved in an organic solvent such as toluene, dichloromethane, dichloroethane or tetrahydrofuran, and the carrier is immersed in the solution, or the solution is sprayed on the carrier and dried. The drying temperature is preferably 120 to 200 ° C.

Further, in order to form a sufficient coating film and obtain uniform chargeability, moisture resistance and durability, the concentration of the coating resin solution is preferably 3 to 30% by weight. In order to obtain the above characteristics, the thickness of the coating layer is preferably about 0.1-5 μm. For the toner having a low charging property, a carrier which is easy to have a charging property opposite to that of the toner is selected and used.

Further, the charge amount of the toner in the developer here is ± by a blow-off charge amount measuring device (manufactured by Toshiba Chemical Co.).
It is preferably 5 to 40 μc / g, particularly ± 10 to 30 μc / g. If the amount of blow-off charge is less than ± 5 μc / g, toner may scatter or the image may be extremely fogged when the developer is stirred. Also, ± 40 μc
If it exceeds / g, the image density becomes extremely low.

The developer of the present invention is used in various development processes,
For example, the cascade developing method described in U.S. Pat. No. 2,618,552, the magnetic brush method described in U.S. Pat. No. 2,870,405, and U.S. Pat. No. 222.
It can be used for the powder cloud method described in US Pat. No. 17,761, and the touch-down developing method described in US Pat. No. 3,166,432.

The developer of the present invention can be used in various fixing methods such as so-called oilless and oil coating heat roll method, flash method, oven method and pressure fixing method. Further, the developer of the present invention can be used in various cleaning methods such as so-called fur brush method and blade method.

The developer of the present invention is used in an image forming method in which an electrostatic latent image formed on a photoconductor is brought into contact with the latent image to be visualized, transferred to a support and fixed. In particular, it can be effectively applied to an image forming method in combination with a photoconductor made of an organic photoconductive substance.

The photosensitive member is preferably a function-separated type in which the charge-generating layer and the charge-transporting layer which are excellent in sensitivity are different from each other. Generally, in the charge generation layer, azoxybenzene-based, disazo-based, trisazo-based, benzimidazole-based, polycyclic quinoline-based, indigoid-based, quinacridone-based, phthalocyanine-based, perylene-based, methine-based pigments are known. (JP-A-47-37543, JP-A-47-37544)
JP-A-47-18543, JP-A-47-1854
4, JP-A-48-43942, JP-A-48-705.
38, JP-A-49-1231, JP-A-49-105.
536, JP-A-50-75214, and JP-A-50-
Any of these can be applied, but phthalocyanine-based pigments are particularly preferable from the viewpoint of charge generation efficiency. In addition, the charge transport layer has a pyrazoline derivative (Journal of Photographic Science and Engineering).
Photographic Science and
Engineering) Volume 21, No. 2, 73
Page, 1977), oxazole derivatives (JP-A-55-55)
No. 35319, JP-A-58-87557 and JP-A-5.
8-182640) Hydrazone derivative
4-59143, JP-A-54-150128 and JP-A-55-46760, enamine derivatives (Journal of Imaging Science (Journ).
al of Imaging Science) No. 29
Vol. 1, No. 1, p. 7, 1985), butadiene derivatives and the like are known and used.

Further, as the binder resin for fixing these organic photoconductive substances to the support material of the photoreceptor, polycarbonate resin, esterified polycarbonate resin, silicone resin, styrene resin, styrene-acrylic resin, polyamide resin, polyester resin , Polyvinyl butyral resin, etc. are used. In the image forming method of the present invention, the magnetic brush method is preferably used as the developing method and the hot roll method is preferably used as the fixing method, but the invention is not limited thereto.

[0036]

EXAMPLES The present invention will now be described with reference to examples, but the present invention is not limited thereto. "%" In the examples
Means “% by weight” unless otherwise specified.

Resin Synthesis Example 1 In a four-necked separable flask equipped with a stirrer, a nitrogen inlet, a thermometer and a condenser, 200 g of ion-exchanged water and a 10% tricalcium phosphate aqueous solution (Supertite 10
10 g of Nippon Kagaku Co., Ltd. was added, and then 50 g of styrene, 20 g of butyl methacrylate and 3 g of benzoyl peroxide were added thereto, and polymerization was carried out at 85 ° C. for 4 hours. Then, the mixture was cooled to 40 ° C., 20 g of styrene, 10 g of butyl methacrylate, and 0.15 of divinylbenzene.
g, 1,1-bis (t-butylperoxy) 3,3,5
-Trimethylcyclohexane (Perhexa 3M, manufactured by NOF CORPORATION) was added, and the mixture was stirred at 50 ° C for 1 hour, and then polymerized at 80 ° C for 4 hours and 90 ° C for 4 hours. The obtained resin (designated as styrene-acrylic resin 1) was dried, and the gel content was measured with a Soxhlet extractor using methyl ethyl ketone as a solvent, and it was 28%.

Resin Synthesis Example 2 In the same manner as in Synthesis Example 1, 35 g of styrene and 15 g of butyl methacrylate were polymerized with 2.5 g of benzoyl peroxide in the first stage, and then styrene 35 in the second stage.
g, 15 g of butyl methacrylate and 0.2 g of divinylbenzene were polymerized with 1 g of Perhexa 3M. The obtained resin (designated as styrene-acrylic resin 2) is dried,
The gel content was measured and found to be 48%.

Resin Synthesis Example 3 Using the same apparatus as in Synthesis Example 1, ion-exchanged water 200
g, Supertite 1010 g, styrene 70 g, butyl methacrylate 30 g, divinylbenzene 0.1
g and benzoyl peroxide 3 g were added, and polymerization was carried out at 80 ° C. for 4 hours and at 90 ° C. for 4 hours. The resin obtained (designated as styrene-acrylic resin 3) was dried and the gel content was measured and found to be 58%.

Resin Synthesis Example 4 Using the same apparatus as in Synthesis Example 1, ion-exchanged water 200
g, Supertite 1010 g, styrene 70 g, butyl methacrylate 30 g, and benzoyl peroxide 3 g were added, and polymerization was carried out at 80 ° C. for 4 hours and at 90 ° C. for 4 hours. Obtained resin (styrene-acrylic resin 4)
Was dried and the gel content was measured, but there was no gel content.

Resin Synthesis Example 5 In the same manner as in Synthesis Example 1, 60 g of styrene and 25 g of butyl methacrylate were polymerized with 3 g of benzoyl peroxide in the first stage, and then 10 g of styrene, 5 g of butyl methacrylate and divinylbenzene in the second stage. 0.06g
Was polymerized with 0.5 g of Perhexa 3M. The resin obtained (designated as styrene-acrylic resin 5) was dried and the gel content was measured and found to be 15%.

Example 1 85 parts by weight of styrene-acrylic resin 1 produced in Synthesis Example 1 was added to carbon black as a colorant (specific surface area 2 according to Vulcan XC72 BET method, manufactured by Cabot Corporation).
40 m ² / g) 9 parts by weight, magnetite (Mitsui Kinzoku Kogyo, MG-WL, specific surface area by BET method 2 m ² / g)
1 part by weight, 2 parts by weight of nigrosine-based charge control agent (manufactured by Orient Chemical Industry Co., Ltd., Bontron S-34), low molecular weight polypropylene (manufactured by Sanyo Chemical Industry Co., Ltd., Viscole 6)
60P) 2 parts by weight were mixed and kneaded with a twin-screw kneader PCM-30 manufactured by Ikegai Tekko KK to obtain a gel content of 5%. Then,
After coarse pulverization with a hammer mill, fine pulverization with a jet mill, and classification with a zigzag classifier, styrene-
Acrylic toner 1 was prepared. The particle size of this toner measured with a Coulter Counter (manufactured by Coulter) is 4
˜15 μm, average particle size was 8 μm. In addition, the subsequent particle size was also measured with a Coulter counter.

Manufacture of Developer A ferrite carrier (F-200, manufactured by Powder Tech Co., Ltd.) was added as a carrier to the produced styrene-acrylic toner 1 so that the toner / carrier would be 4/96 (weight ratio). Then, mix with a V-type blender to prepare developer 1.
It was created. Blow-off charge (Toshiba Chemical Co., Ltd.)
Manufactured by Blow-off powder charge amount measuring device),
It was −21 μc / g.

Example 2 85 parts by weight of styrene-acrylic resin 185 produced in Synthesis Example 1, carbon black (manufactured by Cabot Co., Vulcan
XC72) 7 parts by weight, magnetite (manufactured by Mitsui Kinzoku Kogyo,
MG-WL) 3 parts by weight, nigrosine type charge control agent (Orient Chemical Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (Sanyo Chemical Co., Ltd.),
Viscole 660P) 2 parts by weight, and kneader PCM
The mixture was kneaded at -30 to give a gel content of 0%. Then, a styrene-acrylic toner 2 was prepared through coarse pulverization with a hammer mill, fine pulverization with a jet mill, and classification with a zigzag classifier. The particle size of this toner measured with a coulter counter is 4 to 15 μm, and the average particle size is 8
was μm.

Manufacture of Developer A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) obtained by coating the prepared styrene-acrylic toner 2 with a styrene-acrylic resin was used, the toner / carrier being 4/96 (weight ratio). And mixed with a V-type blender to prepare a developer 2. The blow-off charge amount of the developer was −23 μc / g.

Example 3 85 parts by weight of styrene-acrylic resin 2 produced in Synthesis Example 2, carbon black (manufactured by Cabot Corp., Black Pearls 1000, specific surface area 340 m ² by BET method)
/ G) 8 parts by weight, magnetite (Mitsui Kinzoku Kogyo, MG
-Specific surface area by LZ BET method 3 m ² / g) 2 parts by weight, Nigrosine type charge control agent (Orient Chemical Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (Sanyo Kasei Co., Ltd.) , Viscole 66
0P) 2 parts by weight were blended and kneaded with a kneader PCM-30 to make a gel content 0%. Then, styrene-acrylic toner 3 was prepared through coarse pulverization with a hammer mill, fine pulverization with a jet mill, and classification with a zigzag classifier. The particle size of this toner measured with a Coulter Counter was 4 to 15 μm, and the average particle size was 8 μm.

Manufacture of Developer A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) obtained by coating the prepared styrene-acrylic toner 3 with a styrene-acrylic resin was used, the toner / carrier being 4/96 (weight ratio). And blended in a V-type blender to prepare a developer 3. The blow-off charge amount of the developer was -21 μc / g.

Example 4 85 parts by weight of styrene-acrylic resin 2 produced in Synthesis Example 2, carbon black (Valcan manufactured by Cabot Corporation)
XC72) 7 parts by weight, magnetite (manufactured by Mitsui Kinzoku Kogyo,
MG-LZ) 3 parts by weight, Nigrosine-based charge control agent (Orient Chemical Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (Sanyo Chemical Co., Ltd.),
Viscole 660P) 2 parts by weight, and kneader PCM
The mixture was kneaded at -30 to give a gel content of 5%. Then, styrene-acrylic toner 4 was prepared through coarse pulverization with a hammer mill, fine pulverization with a jet mill, and classification with a zigzag classifier. The particle size of this toner measured with a coulter counter is 4 to 15 μm, and the average particle size is 8
was μm.

Manufacture of Developer A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) obtained by coating the prepared styrene-acrylic toner 4 with a styrene-acrylic resin was used, the toner / carrier being 4/96 (weight ratio). And mixed with a V-type blender to prepare a developer 4. The blow-off charge amount of the developer was -24 μc / g.

Comparative Example 1 85 parts by weight of styrene-acrylic resin 3 produced in Synthesis Example 3, carbon black (manufactured by Cabot Co., Vulcan
XC72) 8 parts by weight, magnetite (manufactured by Mitsui Kinzoku Kogyo,
MG-LZ) 2 parts by weight, Nigrosine type charge control agent (Orient Chemical Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (Sanyo Chemical Co., Ltd.),
Viscole 660P) 2 parts by weight, and kneader PCM
The mixture was kneaded at -30 to give a gel content of 5%. Then, styrene-acrylic toner 5 was prepared through coarse pulverization with a hammer mill, fine pulverization with a jet mill, and classification with a zigzag classifier. The particle size of this toner measured with a coulter counter is 4 to 15 μm, and the average particle size is 8
was μm.

Manufacture of Developer A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) in which the prepared styrene-acrylic toner 5 is coated with styrene-acrylic resin is used, the toner / carrier is 4/96 (weight ratio). And mixed with a V-type blender to prepare a developer 5. The blow-off charge amount of the developer was −23 μc / g.

Comparative Example 2 85 parts by weight of styrene-acrylic resin 4 produced in Synthesis Example 4, carbon black (manufactured by Cabot Co., Vulcan
XC72) 8 parts by weight, magnetite (manufactured by Mitsui Kinzoku Kogyo,
MG-LZ) 2 parts by weight, Nigrosine type charge control agent (Orient Chemical Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (Sanyo Chemical Co., Ltd.),
Viscole 660P) 2 parts by weight, and kneader PCM
Kneaded at -30. Then, styrene-acrylic toner 6 was prepared through coarse pulverization with a hammer mill, fine pulverization with a jet mill, and classification with a zigzag classifier. The particle size of this toner measured with a Coulter Counter was 4 to 15 μm, and the average particle size was 8 μm.

Manufacture of Developer A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) coated with a styrene-acryl-based toner 6 as a trial was coated with a styrene-acryl-based resin, and the toner / carrier was 4/96 (weight ratio). And mixed with a V-type blender to prepare a developer 6. The blow-off charge amount of the developer was -21 μc / g.

Comparative Example 3 85 parts by weight of styrene-acrylic resin 5 produced in Synthesis Example 5, carbon black (manufactured by Cabot Co., Vulcan
XC72) 8 parts by weight, magnetite (manufactured by Mitsui Kinzoku Kogyo,
MG-LZ) 2 parts by weight, Nigrosine type charge control agent (Orient Chemical Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (Sanyo Chemical Co., Ltd.),
Viscole 660P) 2 parts by weight, and kneader PCM
The mixture was kneaded at -30 to give a gel content of 0%. Then, styrene-acrylic toner 7 was prepared through coarse pulverization with a hammer mill, fine pulverization with a jet mill, and classification with a zigzag classifier. The particle size of this toner measured with a coulter counter is 4 to 15 μm, and the average particle size is 8
was μm.

Manufacture of Developer A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) in which the prepared styrene-acrylic toner 7 is coated with styrene-acrylic resin is used, the toner / carrier is 4/96 (weight ratio). And mixed with a V-type blender to prepare a developer 7. The blow-off charge amount of the developer was -21 μc / g.

Comparative Example 4 85 parts by weight of styrene-acrylic resin 2 produced in Synthesis Example 2, carbon black (manufactured by Cabot Corp., Vulcan
XC72) 8 parts by weight, magnetite (manufactured by Mitsui Kinzoku Kogyo,
MG-LZ) 2 parts by weight, Nigrosine type charge control agent (Orient Chemical Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (Sanyo Chemical Co., Ltd.),
Viscole 660P) 2 parts by weight, and kneader PCM
The mixture was kneaded at -30 to give a gel content of 18%. Then, a styrene-acrylic toner 8 was prepared through coarse pulverization with a hammer mill, fine pulverization with a jet mill, and classification with a zigzag classifier. The particle size of this toner measured with a Coulter Counter was 5 to 20 μm, and the average particle size was 8 μm.

Manufacture of Developer A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) in which the prepared styrene-acrylic toner 8 is coated with styrene-acrylic resin is used, the toner / carrier is 4/96 (weight ratio). And mixed with a V-type blender to prepare a developer 8. The blow-off charge amount of the developer was −20 μc / g.

Comparative Example 5 Styrene-acrylic resin 185 produced in Synthesis Example 1 (85 parts by weight), carbon black (manufactured by Cabot Co., Vulcan
XC72) 10 parts by weight, Nigrosine-based charge control agent (Orient Chemical Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (Sanyo Chemical Co., Ltd.),
Viscole 660P) 2 parts by weight, and kneader PCM
The mixture was kneaded at -30 to give a gel content of 0%. Then, styrene-acrylic toner 9 was prepared through coarse crushing with a hammer mill, fine crushing with a jet mill, and classification with a zigzag classifier. The particle size of this toner measured with a coulter counter is 4 to 15 μm, and the average particle size is 8
was μm.

Manufacture of Developer A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) obtained by coating the prepared styrene-acrylic toner 9 with a styrene-acrylic resin was used, and the toner / carrier was 4/96 (weight ratio). And blended in a V-type blender to prepare a developer 2. The blow-off charge amount of the developer was -21 μc / g.

Comparative Example 6 85 parts by weight of styrene-acrylic resin 1 produced in Synthesis Example 1, carbon black (manufactured by Cabot Corp., Black Pearls L, specific surface area by BET method 140 m ² / g)
8 parts by weight, magnetite (Mitsui Kinzoku Kogyo, MG-L
Z) 2 parts by weight, Nigrosine type charge control agent (manufactured by Orient Chemical Industry Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (manufactured by Sanyo Chemical Industry Co., Ltd., Viscole 660P) 2 parts by weight are blended. Then, the mixture was kneaded with a kneader PCM-30 to make the gel content 0%. Then, after coarsely pulverizing with a hammer mill, finely pulverizing with a jet mill, and further classifying with a zigzag classifier, styrene-acrylic toner 1
0 was created. The particle size of this toner measured with a Coulter Counter was 4 to 15 μm, and the average particle size was 8 μm.

Manufacture of Developer Styrene-acryl-based toner 10 prepared was mixed with styrene-
A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) coated with an acrylic resin is mixed so that the toner / carrier becomes 4/96 (weight ratio), mixed with a V-type blender, and the developer 10 is added. Created.
The blow-off charge amount of the developer was −23 μc / g.

Comparative Example 7 85 parts by weight of styrene-acrylic resin 1 produced in Synthesis Example 1, carbon black (MA-6 manufactured by Mitsubishi Kasei Co., Ltd.)
00 specific surface area by BET method 150 m ² / g) 8 parts by weight, magnetite (Mitsui Kinzoku Kogyo, MG-WS B
Specific surface area by ET method 9 m ² / g) 2 parts by weight, Nigrosine type charge control agent (Orient Chemical Co., Ltd., Bontron S-34) 2 parts by weight, low molecular weight polypropylene (Sanyo Kasei Co., Ltd., Viscole) 660P) 2 parts by weight, and kneaded with a kneader PCM-30 to give a gel content of 0%.
And Then, styrene-acrylic toner 11 was prepared through coarse pulverization with a hammer mill, fine pulverization with a jet mill, and classification with a zigzag classifier. The particle size of this toner measured with a Coulter Counter is 4
˜15 μm, average particle size was 8 μm.

Manufacture of Developer Styrene-acryl-based toner 11 prepared was mixed with styrene-
A ferrite carrier (F288-200, manufactured by Powder Tech Co., Ltd.) coated with an acrylic resin is mixed so that the toner / carrier becomes 4/96 (weight ratio), mixed with a V-type blender, and the developer 11 is added. It was made.
The blow-off charge amount of the developer was -25 μc / g.

The characteristics of each developer were evaluated by the following evaluation methods. (1) Kneading property The kneading speed was evaluated when kneading was performed using a kneader PCM-30. 4: Kneading is very fast. 3: Kneading is fast. 2: Kneading is slow. 1: Kneading is very slow.

(2) Toner Yield When the toner is pulverized, the weight ratio (%) of the product toner amount to the charged kneading toner amount.

(3) Image Evaluation (Image Forming) Method Laser beam printer (photoreceptor: τ-type metal-free phthalocyanine pigment for charge generation layer, organic photoreceptor using butadiene derivative for charge transport layer, dot density: 600 dp
i, printing speed: 10 sheets / minute, a semiconductor laser, a magnetic brush developing machine, a two-component reversal developing system, a heat roll fixing, a bias voltage of −100 v) were used for evaluation.

(A): Line Image Density Each of the prepared developers was printed with the letter "I" using the above laser beam printer. The density of the letter "I" was measured with a microphotometer manufactured by Union Optical Co., Ltd. The measured values were converted to Macbeth concentration values and judged.

(B): Initial surface image density An image of 3 × 3 cm was output in the same manner as the linear image density. The density of the central portion was measured using a Macbeth densitometer and judged.

(C): Time-dependent surface image density In the same manner as the initial surface image density, a 3 × 3 cm image is subjected to 5K.
P continuous printing was performed, and the density at the time of 5KP printing was determined by measuring the density at the central portion using a Macbeth densitometer.

(D): Fog Density A blank sheet was output in the same manner as the line image density. The fog density was determined from the difference between the density of the paper before output and the density of the paper after output using a reflection densitometer (TC-6DS manufactured by Tokyo Denshoku Co., Ltd.).

(E): Resolution 1.6 lines / inch, 2.0 in the same manner as the line image density.
Line / inch, 2.5 line / inch, 3.2 line / inch, 4.0 line / inch, 5.0 line / inch, 6.3 line / inch, 8.0 line / inch, 1
0.0 line / inch, 12.5 line / inch, 16
Output line drawing of line / inch. The maximum number of lines that the output image can read in detail is shown.

(F): Durability Each of the prepared developers was used in a copying machine at a temperature of 30 ° C.
10000 sheets were continuously copied under the condition of relative humidity of 80%. The scattering of the toner generated at this time was examined and judged by the following evaluation. 4: There is no toner scattering. 3: Some scattering of toner is seen. 2: A lot of toner is scattered. 1: A large amount of toner is scattered.

(G): Offset resistance Sanyo Denki Co., Ltd. Shatrex 806 Copier machine was modified to change the fixing temperature of the heat fixing roll of the copying machine from 60 ° C to 230 ° C, and each toner was copied. An unfixed image was output using a machine. Using the output unfixed image, the fixing temperature was changed and the temperature range in which offset did not occur was investigated.

(H): Fixability The output unfixed image was fixed at a temperature of 190 ° C. using the same fixing device as used in the offset resistance evaluation. Then, a scotch tape was attached to the fixed image, and peeled off after 10 minutes, and the change in image density was evaluated by the following formula. Fixability (%) = (concentration after peeling off cellophane tape / concentration before peeling off cellophane tape) × 100 The evaluation results of Examples 1 to 4 and Comparative Examples 1 to 7 are shown in Table 1.

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[Table 1]

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INDUSTRIAL APPLICABILITY The dry toner produced by the present invention and the electrophotographic developer using the same are excellent in a wide range of offset resistance, line image print density, and plane image print density, and have less fog and have a very high resolution. High-definition images can be obtained. Further, the developer can have a long life. Therefore, the image forming method using the electrophotographic developer according to the present invention can obtain an image of excellent image quality for a long time in an electrophotographic copying machine, a laser beam printer or the like.

Front Page Continuation (72) Inventor Takashi Ikeda 4-13-1, Higashimachi, Hitachi, Ibaraki Hitachi Chemical Co., Ltd. Yamazaki Plant (72) Inventor Takeo Kudo 4-13-1, Higashimachi, Hitachi, Hitachi Kasei Kogyo Co., Ltd. Yamazaki Plant (72) Inventor Masayoshi Yoshikubo 4-13-1 Higashimachi, Hitachi City, Ibaraki Hitachi Chemical Co., Ltd. Yamazaki Plant

Claims (7)

[Claims] 1. A vinyl resin having a gel content of 20 to 50% by weight, carbon black having a specific surface area of 200 m ² / g or more and magnetite having a specific surface area of 6 m ² / g or less are added as a colorant to obtain a gel content. A method for producing a dry toner, which comprises melt-kneading until the content becomes 10% by weight or less. 2. The method for producing a dry toner according to claim 1, wherein the vinyl resin is a styrene-acrylic resin. 3. An electrophotographic developer comprising a dry toner obtained by the production method according to claim 1 and a carrier. 4. The electrophotographic developer according to claim 3, wherein the carrier is a ferrite carrier. 5. The electrophotographic developer according to claim 3, wherein the carrier is coated with a resin. 6. An electrostatic latent image formed on a photoconductor is brought into contact with the electrophotographic developer according to claim 3, 4 or 5 to visualize the image, and the image is transferred to a support and fixed. And an image forming method. 7. The image forming method according to claim 6, wherein the photoreceptor is an organic photoreceptor having a phthalocyanine-based pigment as a charge generation layer.