JPH05127421A - Electrophotographic developing method - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic developing method using a small particle size toner by which such problems as base contamination and splashing of toner when a recycled toner is used can be solved and picture images excellent in resolution, sharpness, and half tone reproducibility can be stably obtd. CONSTITUTION:In this dry two-component developing method, electrostatic latent images on a image carrier are developed, transferred to a transfer paper and then the toner remaining on the carrier is cleaned and collected to a developer device or into a replenishing toner. The toner used essentially consists of resin particles (A) obtd. by polymn. of polymerizable monomers to satisfy the retio of 1.00<(Dv/Dp)<=1.20, wherein Dv is the volume average particle size and Dp is the number average particle size of the resin and Dv is 1-20mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic developing method, and more particularly to a dry two-component electrophotographic developing method for collecting and reusing untransferred toner remaining on an image bearing member.

[0002]

2. Description of the Related Art Generally, in an electrophotographic apparatus, an electrostatic latent image on an image carrier is developed, and then a toner image is transferred onto a transfer paper by a biasing transfer roller or a corona charger. At that time, about 20% by weight of untransferred toner remains on the image carrier. Therefore, it has been attempted to clean and collect the untransferred toner (hereinafter, this toner is referred to as recycled toner) and reuse it. In particular, in a high-speed electrophotographic apparatus, a large amount of toner is generated after cleaning, so that the use of recycled toner has been seriously studied. If recycled toner can be used, the toner can be effectively used, the space inside the machine can be significantly saved, and the machine can be made compact. As described above, the reason why the recycled toner is not so actively used despite the desire to use the recycled toner is mainly due to the following reasons. That is, when the recycled toner is used, scumming and toner scattering easily occur. Conventionally, it has been considered that the cause is paper dust, dust, etc. of transfer paper, and therefore a mesh for removing them has been provided in the recycling toner recovery path. Further, during cleaning and in the recovery path, the toner may be charged with a polarity opposite to that obtained by friction with the carrier. As a countermeasure, a member that comes in contact with toner is given the same triboelectrification polarity as the carrier, a corona charger for removing the electric charge remaining in the toner, or a corona with the same polarity as the electric charge obtained by triboelectrification with the carrier. Attempts were made to use a charger. Furthermore, a polarity control agent that is not easily charged to the opposite polarity in the recovery route has been studied. However, in spite of the above measures, the current situation is that the background stain and the toner scattering are not sufficiently improved.
On the other hand, in order to improve the image quality of the electrophotographic system, it is required to reduce the toner particle size, have sufficient coloring power, and control the charge uniformly. The smaller particle size of the toner improves the resolution, sharpness, halftone reproducibility, and photographic reproducibility. However, a conventional general toner manufacturing method, that is, a toner obtained by melt-kneading a resin, a dye / pigment, and a charge control agent, mechanically pulverizing and classifying the toner is There was such a drawback. That is, (1) The smaller the particle size, the poorer the toner charging characteristics due to the non-uniform dispersion of the charge control agent, and the more easily the background stain and the toner scattering occur. (2) Further, since the surface of the small particle size toner obtained by pulverization has many protrusions, the toner constituent material is easily separated,
Filming of the carrier, the frictional charging member, or the photoconductor is likely to occur. (3) When the particle size is reduced, the coloring power of each toner weakens. (4) It is difficult to clean the small particle toner remaining on the photoconductor. (5) The production capacity and the yield are remarkably reduced and the cost is increased.

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is (1) background stains which occur when recycled toner is used,
To provide an electrophotographic developing method capable of effectively utilizing toner by overcoming the problem of toner scattering. (2) Another object of the present invention is to provide an electrophotographic developing method using a toner having a small particle diameter, which can stably obtain excellent image quality such as resolution, sharpness and halftone reproducibility.

[0004]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have made a new study on the mechanism of background stain and toner scattering, and have found the following. That is, when a continuous copy test was conducted using an electrophotographic apparatus modified so that the recycled toner was returned to the toner replenishing device, the background gradually began to scatter and toner scattering began to occur. Furthermore, as I continued the copy test, it got worse and finally I could not continue the test. Therefore, when we measured various characteristics of the developer that was sequentially sampled from the beginning of the copy test, the samples before and after the start of the background stain
There was a difference in the particle size of the toner in the developer. The sample after the occurrence of background stain had a small average particle size measured by a Coulter counter. Further, when observed with a scanning electron microscope, it was found that the toner having an extremely small particle diameter tightly covered the carrier surface. When the sample after that was examined, it was found that the toner having the extremely small particle size covering the carrier was hardly reduced. As a result of diligent examination of the cause of such a phenomenon, most of the toner having a small particle size among the developed toner remains on the image carrier without being transferred, and this toner returns to the toner replenishing device, It has been found that replenishment in the developer gradually covers the surface of the carrier. In particular, when the toner in the toner replenishment tank is running low, the amount of ultra-small particle size toner covering the carrier rapidly increases. Further, even if the toner tank is replenished with new toner, once the carrier is covered with the toner having the extremely small particle size, the toner is not recovered. Therefore, in such a state, even if the toner is replenished in the developer, it is difficult for the toner to come into direct contact with the carrier surface, and the toner cannot obtain a sufficient charge, resulting in background stains and toner. I found out that the scattering was happening. Further, it has been found that the above tendency becomes worse when the average particle size of the toner for replenishment is reduced to improve the image quality. In order to avoid the above phenomenon, the inventors of the present invention have earnestly studied,
It is effective to narrow the particle size distribution of the toner.
It has been found that when the following developing method is used, the high image quality is maintained without the problems associated with the use of recycled toner. That is, after the electrostatic latent image on the image carrier is developed and the toner image is transferred to the transfer paper, the toner remaining on the image carrier is cleaned, and then this toner is stored in the developing device or the replenishing toner. In a dry two-component developing method in which the resin particles A obtained by polymerizing a polymerizable monomer are used as a matrix, the volume average particle diameter (Dv) and the number average particle diameter (Dp) of the resin particles are used. ) Ratio is 1.00 ≦ (Dv / Dp) ≦ 1.
The electrophotographic developing method is characterized in that a toner having a Dv of 1 to 20 μm in a range of 20 is used.

As the resin particles A, those produced by various polymerization methods or those which have been subjected to post-treatment such as classification operation can be used. In particular, development using a toner produced by the following method The method is preferred. A polymer dispersant that dissolves in the hydrophilic organic liquid is added to the hydrophilic organic liquid, and the polymer is dissolved in the hydrophilic organic liquid, but is the resulting polymer expanded by the hydrophilic organic liquid? In an organic solvent that does not dissolve the resin particles A in the resin particles (hereinafter referred to as resin particles A), which is produced by adding one or more vinyl monomers that are almost insoluble and polymerizing Obtained by dispersing the resin particles A in, and after or after dissolving the dye in the solvent, permeating the dye into the resin particles A for coloring, and then removing the organic solvent. This is an electrophotographic development method using a toner in which resin particles A are uniformly dyed from the surface to the inside. Of the developed toner, those with a small particle size
Although transfer residual toner (recycled toner) is likely to occur during transfer, the particle size of the transfer residual toner does not decrease in the developing method of the present invention. Therefore, the surface of the carrier is not covered with the recycled toner, and the triboelectric chargeability of the carrier does not deteriorate. Further, it was found that the high image quality was maintained without the chargeability of the recycled toner itself being deteriorated. When Dv / Dp exceeds 1.20, the ratio of the small particle size toner to the toner particle size distribution increases, and the difference in particle size between the transferred toner and the transfer residual toner increases, and the recycled toner gradually becomes the carrier. To cover the surface,
Causes scumming and toner scattering. As a method for cleaning the toner after transfer from the image carrier, there are a web cleaning method, a fur brush cleaning method, an elastic blade cleaning method, a magnetic brush cleaning method, and a cleaning method using a combination thereof. As a method of using recycled toner, it is possible to return the cleaned toner to the developer each time, or to return it to the toner tank for replenishment, stir well, and then replenish it to the developer, Either is fine. The developer used in the present invention is a dry two-component developer using a carrier, and any carrier conventionally used for electrophotography can be used.

Resin Particle A Resin particle A in the present invention is as follows. That is, in the resin particles A, the ratio of the volume average particle diameter (Dv) to the number average particle diameter (Dp) is 1.00 ≦ (Dv / Dp) ≦ 1.20.
, And Dv is 1 to 20 μm. In the resin particles, a polymer dispersant that dissolves in the hydrophilic organic liquid is added to the hydrophilic organic liquid, and the polymer is dissolved in the hydrophilic organic liquid, but the resulting polymer swells in the hydrophilic organic liquid. Or most of them are insoluble, and one or more vinyl monomers are added and polymerized. It also includes a reaction in which a polymer having a smaller particle size than the intended particle size but having a narrow particle size distribution is used to grow in advance in the above system. The monomer utilized for the growth reaction may be the same monomer that produced the seed particles or a different monomer, but the polymer must not be soluble in the hydrophilic organic liquid. Hydrophilic Organic Liquid As the hydrophilic organic liquid used as a diluent for the monomer used during the formation of seed particles and during the reaction of growing seed particles, for example, methyl alcohol, ethyl alcohol, denatured ethyl alcohol, isopropyl alcohol,
n-butyl alcohol, isobutyl alcohol, ter
t-butyl alcohol, sec-butyl alcohol, t
ert-amyl alcohol, 3-pentanol, octyl alcohol, benzyl alcohol, cyclohexanol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethylene glycol, glycerin, diethylene glycol and other alcohols, methyl cellosolve, cellosolve, isopropyl cellosolve, butyl cellosolve, ethylene. Examples include ether alcohols such as glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether.
These organic liquids may be used alone or as a mixture of two or more. It should be noted that, by using together with the above-mentioned alcohols and ether alcohols in organic liquids other than alcohols and ether alcohols, various SP values can be obtained under the condition that the produced polymer particles of the organic liquid have no solubility. It is possible to suppress the size of particles produced and the coalescence of seed particles and the generation of new particles by changing polymerization conditions. As the organic liquid used in combination with these, hexane, octane, petroleum ether, cyclohexane, benzene, toluene, xylene and other hydrocarbons, carbon tetrachloride, trichloroethylene, tetrabromoethane and other halogenated hydrocarbons, ethyl ether, Ethers such as dimethyl glycol, trioxane and tetrahydrofuran, acetals such as methylal and diethyl acetal, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexane, esters such as butyl formate, butyl acetate, ethyl propionate and cellosolve acetate. Acids such as formic acid, acetic acid and propionic acid, nitropropene, nitrobenzene, dimethylamine, monoethanolamine, pyridine, dimethylsulfoxide, dimethylformamide, etc. Containing organic compounds, and other, water is also included. SO ₄ ²⁻ , NO ₂ ⁻ , PO ₄ ³⁻ , C are added to the above-mentioned solvent mainly composed of hydrophilic organic liquid.
Polymerization may be carried out in the presence of l ⁻ , Na +, K +, Mg ² +, Ca ² + and other inorganic ions. Further, at the start of the polymerization and during the polymerization, the end of the polymerization and the average particle diameter of the polymer particles produced by changing the type and composition of the mixed solvent,
The particle size distribution, drying conditions, etc. can be adjusted.

Dispersion Stabilizers Suitable examples of dispersion stabilizers during the production of seed particles or growth particles include, for example, acrylic acid, methacrylic acid,
Acids such as α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride, or an acrylic monomer containing a hydroxyl group, for example β-hydroxyethyl acrylate, Β-Hydroxyethyl methacrylate, β-acrylic acid
-Hydroxypropyl, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-chloro-acrylate
2-hydroxypropyl, 3-chloro-2 methacrylate
-Hydroxypropyl, diethylene glycol monoacrylic acid ester, diethylene glycol monomethacrylic acid ester, glycerin monoacrylic acid ester, glycerin monomethacrylic acid ester, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, for example Vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc., or esters of compounds containing vinyl alcohol and a carboxyl group, such as vinyl acetate, vinyl propionate, vinyl butyrate, etc.,
Having acrylamide, methacrylamide, diacetone acrylamide, or their methylol compounds, acid chlorides such as acrylic acid chloride and methacrylic acid chloride, nitrogen atom such as vinylpyridine, vinylpyrrolidone, vinylimidazole, ethyleneimine, or a heterocycle thereof Such as homopolymers or copolymers, polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamines, polyoxypropylene alkylamines, polyoxyethylene alkylamides,
Polyoxyethylene type such as polyoxypropylene alkyl amide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ether, polyoxyethylene nonyl phenyl ether, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc. Cellulose, or a copolymer of the above hydrophilic monomer with a benzene nucleus such as styrene, α-methylstyrene or vinyltoluene or a derivative thereof or an acrylic acid or methacrylic acid derivative such as acrylonitrile, methacrylonitrile or acrylamide. In addition, crosslinkable monomers such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, methacrylic acid Allyl, a copolymer of divinylbenzene can be used. These polymer compound dispersants may be appropriately selected depending on the hydrophilic organic liquid to be used, the seed of the intended polymer particles and the production of seed particles or the production of grown particles, but especially the unification of the polymer particles with each other. Mainly in terms of steric prevention, a polymer having a high affinity for the polymer particle surface and an adsorptive property and a high affinity for a hydrophilic organic liquid and a high solubility is selected. Further, in order to increase the repulsion between the particles in a three-dimensional manner, the molecular chain having a certain length, preferably,
Those having a molecular weight of 10,000 or more are selected. However, if the molecular weight is too high, the liquid viscosity will remarkably increase, the operability and the stirring property will be deteriorated, and the precipitation probability of the produced polymer on the particle surface will vary, so caution is required. It is also effective for stabilization that a part of the above-mentioned polymer compound dispersant monomer is allowed to coexist with the monomer constituting the target polymer particles. Further, in combination with these polymer compound dispersants, metals such as cobalt, iron, nickel, aluminum, copper, tin, lead and magnesium or alloys thereof (especially 1
In addition, fine particles of inorganic compounds of oxides such as iron oxide, copper oxide, nickel oxide, zinc oxide, titanium oxide, and silicon oxide, higher alcohol sulfate ester salts, alkylbenzene sulfonates, α-olefin sulfonates are preferable. Salt, anionic surfactant such as phosphate ester, alkylamine salt, aminoalcohol fatty acid derivative, polyamine fatty acid derivative, amine salt type such as imidazoline, alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, Pyridium salts, alkylisoquinolinium salts, quaternary ammonium salt type cationic surfactants such as benzethonium chloride, nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives, such as alanine type [eg, dodecyldiene (Ami The use of amino acid type or betaine type amphoteric surfactants such as noethyl) glycine and di (octylaminoethyl) glycine] can further enhance the stability and particle size distribution of the produced polymer particles.

Generally, the amount of the polymer stabilizer used in the production of the seed particles varies depending on the kind of the polymerizable monomer for forming the intended polymer particles, but is 0.1 to the hydrophilic organic liquid.
10% by weight, more preferably 1 to 5% by weight.
When the concentration of the polymer dispersion stabilizer is low, the polymer particles produced have a relatively large particle size, and when the concentration is high, a small particle size is obtained, but 10% by weight is used. Even if it is used in excess, it has little effect on reducing the particle size. Needless to say, the above-mentioned polymer dispersion stabilizer and, if necessary, the inorganic fine powder, pigment, and surfactant are required in the production of seed particles, but they are required to combine the particles with each other in the growth reaction. Polymerization may be carried out by allowing it to be present in a vinyl monomer solution or seed particle dispersion liquid added for the purpose of prevention. The particles initially formed are stabilized by the polymer dispersion stabilizer distributed in equilibrium between the hydrophilic organic liquid and the polymer particle surface, but the unreacted vinyl monomer remains in the hydrophilic organic liquid. When present in a considerable amount, it has a somewhat swollen tackiness and overcomes the steric repulsive force of the polymeric dispersion stabilizer to condense. Further, when the amount of the monomer is extremely large with respect to the hydrophilic organic liquid, the produced polymer is completely dissolved and does not precipitate unless the polymerization proceeds to some extent. The state of precipitation in this case takes the form of forming a highly sticky lump. Therefore, the amount of the monomer with respect to the hydrophilic organic liquid at the time of producing the particles is naturally limited, and the amount of the monomer / hydrophilic organic liquid is about 1 or less, although it is slightly different depending on the kind of the hydrophilic organic liquid. , Preferably 1/2 or less.

Monomer In the present invention, a monomer is one that is soluble in a hydrophilic organic liquid, and is, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene. , P-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, p- Styrenes such as n-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, methyl acrylate, ethyl acrylate, acrylic acid n -Butyl, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, acrylic acid Uril, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl, phenyl acrylate, alpha-chloromethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate,
N-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate,
Α-Methyl fatty acid monocarboxylic acid esters such as stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, acrylic acid or methacrylic acid derivatives such as acrylamide, vinyl chloride, vinylidene chloride , Vinyl bromide, vinyl fluoride, and other halogenated vinyls, alone or in a mixture with each other, and containing 50% by weight or more of these.
It means a mutual mixture of these and monomers which can be copolymerized.

Crosslinking Agent Further, the polymer of the present invention may be crosslinked by polymerizing in the presence of a so-called crosslinking agent having two or more polymerizable double bonds in order to enhance offset resistance. As the crosslinking agent preferably used, divinylbenzene, divinylnaphthalene and aromatic divinyl compounds which are derivatives thereof, other ethylene glycol dimethacrylate, diethylene glycol methacrylate, triethylene glycol methacrylate, trimethylolpropane triacrylate, allyl methacrylate, tert-
Diethylenic carboxylic acid esters such as butylaminoethyl methacrylate, tetraethylene glycol methacrylate, 1,3-butanediol dimethacrylate,
All divinyl compounds such as N, N-divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone and compounds having three or more vinyl groups can be used alone or as a mixture. When the growth polymerization reaction is continuously performed using the seed particles thus crosslinked,
The inside of the growing polymer particles is crosslinked. On the other hand, when the vinyl monomer solution used for the growth reaction contains the above-mentioned cross-linking agent, a polymer whose particle surface is hardened is obtained.

Chain Transfer Agent Further, for the purpose of controlling the average molecular weight, a compound having a large chain transfer constant may be allowed to coexist for polymerization. For example, low molecular compounds with a mercapto group or carbon tetrachloride,
Examples thereof include carbon tetrabromide.

The polymerization initiator used as the polymerization initiator of the monomer is, for example,
Azo polymerization initiators such as 2,2′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile), lauryl peroxide, benzoyl peroxide, tert-butyl peroctoate, etc. The peroxide-based polymerization initiator, the persulfide-based initiator such as potassium persulfate, or a system in which sodium thiosulfate, amine and the like are used in combination is used. The concentration of the polymerization initiator is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the vinyl monomer.

Polymerization conditions As for the polymerization conditions of particles, the concentration and blending ratio of the polymer dispersant and vinyl monomer in the hydrophilic organic liquid are determined according to the target, average particle size and target particle size distribution of the polymer particles. To be done. Generally, if the average particle size of the particles is to be reduced, the concentration of the polymer dispersant is set to be high, and if the average particle size is to be increased, the concentration of the polymer dispersant is set to be low. On the other hand, if the particle size distribution is to be made extremely sharp, the vinyl monomer concentration is set low, and if the distribution is relatively wide, the vinyl monomer concentration is set high. The particles are produced by completely dissolving the polymer dispersion stabilizer in the hydrophilic organic liquid, and then one or more vinyl monomers, a polymerization initiator, and other inorganic fine powder, a surfactant, a dye if necessary. , A pigment, etc. are added, and the mixture is stirred at a normal stirring rate of 30 to 300 rpm, preferably at a speed as low as possible, and at a speed such that the flow in the tank becomes uniform by using a stirring blade of a turbine type rather than a paddle type. However, the polymerization is carried out by heating at a temperature corresponding to the decomposition rate of the used initiator. In addition, since the temperature at the initial stage of polymerization has a great influence on the particle size to be generated, it is preferable to raise the temperature to the polymerization temperature after adding the monomer, and dissolve the initiator in a small amount of solvent and to add it. At the time of polymerization, it is necessary to sufficiently expel oxygen in the air in the reaction vessel with an inert gas such as nitrogen gas or argon gas.
If the oxygen purge is insufficient, fine particles are likely to be generated. In order to carry out the polymerization in a high polymerization rate region, a polymerization time of 5 to 40 hours is required, but the polymerization may be stopped in the state of a desired particle size and particle size distribution, or a polymerization initiator may be added sequentially. Alternatively, the polymerization rate can be increased by carrying out the reaction under high pressure. After completion of the polymerization, it may be used as it is in the dyeing step, or after removing unnecessary fine particles, residual monomers, polymer dispersion stabilizer, etc. by operations such as sedimentation, centrifugation, decantation, etc., the polymer slurry However, if the dispersion stabilizer is not removed, the stability of the dyeing system is higher and unnecessary aggregation is suppressed.

Dyeing Step Dyeing in the present invention is as follows. That is, the resin particles A are dispersed in an organic solvent which does not dissolve the resin particles A, and before or after the dye is dissolved in the solvent, after the dye is penetrated into the resin particles A and colored, In the method of producing a dyed toner by removing the organic solvent, as a dye, the relationship between the solubility of the dye in the organic solvent [D ₁ ] and the solubility of the dye in the resin of the resin particles A [D ₂ ] is shown. , [D ₁ ] / [D ₂ ] ≦
This is to selectively use a dye having a value of 0.5, whereby a toner in which the dye penetrates (diffuses) to the deep part of the resin particle A can be efficiently manufactured.
Solubility is defined herein as measured at a temperature of 25 ° C. The solubility of the dye in the resin is
It has exactly the same definition as the solubility of a dye in a solvent, and means the maximum amount that the dye can be contained in the resin in a compatible state. The observation of the dissolved state or the dye deposition state can be easily performed by using a microscope.
In order to know the solubility of the dye in the resin, an indirect observation method may be used instead of the above direct observation method. In this method, a liquid having a solubility coefficient similar to that of the resin, that is, a solvent that dissolves the resin well, may be used, and the solubility of the dye in the solvent may be determined as the solubility in the resin.

Dye The dye used for dyeing is the ratio of the solubility [D ₁ ] of the dye in the organic solvent used to the solubility [D ₂ ] of the dye in the resin constituting the resin particles, ₁ ] / [D ₂ ] needs to be 0.5 or less. Furthermore, [D ₁ ] / [D ₂ ]
Is preferably 0.2 or less. The dye is not particularly limited as long as it satisfies the above-mentioned solubility characteristics, but water-soluble dyes such as cationic dyes and anionic dyes may have large environmental fluctuations, and the resistance of the toner becomes low, resulting in poor transfer rate. Therefore, vat dyes, disperse dyes and oil-soluble dyes are preferably used, and oil-soluble dyes are particularly preferable. Further, several kinds of dyes can be used together depending on the desired color tone. The ratio (weight) of dye to be dyed and resin particles is
Although it is arbitrarily selected according to the degree of coloring, usually resin particles 1
It is preferable to use 1 to 50 parts by weight of the dye with respect to 00 parts by weight. For example, when alcohols such as methanol and ethanol having a high SP value are used as the dyeing solvent and a styrene-acrylic resin having an SP value of about 9 is used as the resin particles, dyes that can be used include, for example, Such dyes may be mentioned. CI SOLVENT YELLOW (6,9,17,31,35,100,102,103,105) CI SOLVENT ORANGE (2,7,13,14,66,) CI SOLVENT RED (5,16,17,18,19,22,23,143,145,146,
149,150,151,157,158) CI SOLVENT VIOLET (31,32,33,37) CI SOLVENT BLUE (22,63,78,83 ~ 86,91,94,95,104) CI SOLVENT GREEN (24,25,) CI SOLVENT BROWN (3,9 ,) etc. Commercial dyes include, for example, Aizen SOT dye from Hodogaya Chemical Co., Ltd.
Yellow-1,3,4, Orange-1,2,3, Scarlet-1, Red-1,2,3
, Brown-2, Blue-1,2, Violet-1, Green-1,2,3, Bla
ck-1,4,6,8 and BASF sudan dye, Yellow-140,150, O
range-220, Red-290,380,460, Blue-670 and Mitsubishi Kasei dialresin, Yellow-3G, F, H2G, HG, HC, HL, Orange-H
S, G, Red-GG, S, HS, A, K, H5B, Violet-D, Blue-J, G, N,
K, P, H3G, 4G, Green-C, Brown-A and oil color of Orient Chemical Co., Yellow-3G, GG-S, # 105, Orange
-PS, PR, # 201, Scarlet- # 308, Red-5B, Brown-GR, # 41
6, Green-BG, # 502, Blue-BOS, IIN, Black-HBB, # 803, E
E, EX, Sumiplast of Sumitomo Chemical Co., Ltd., Blue GP, OR,
Red FB, 3B, Yellow FL7G, GC, Nippon Kayaku's Kayaron, Polyester Black EX-SH300, Kayaset Red-B
Blue A-2R or the like can be used. Of course, the dye is not limited to the above examples because it is appropriately selected depending on the combination of the resin particles and the solvent used for dyeing.

Organic Solvent for Dyeing The organic solvent used for dyeing the resin particles with the dye is one which does not dissolve the resin particles used, or one which causes some swelling, specifically, the solubility parameter [SP value. ] And the difference is 1.0 or more, preferably 2.0 or more. For example, for styrene-acrylic resin particles, an alcohol type such as methanol, ethanol or n-propanol having a high [SP value] or n-hexane or n-heptane having a low [SP value] is used. Of course, if the difference of [SP value] is too large, the wetting of the resin particles is deteriorated and good dispersion of the resin particles cannot be obtained. Therefore, the optimum [SP value] difference is 2 to 5
Is preferred.

Dyeing Step After dispersing the resin particles in the organic solvent in which the dye is dissolved,
It is preferable to keep the liquid temperature below the glass transition temperature of the resin particles and stir. As a result, the rate of penetration of the dye into the resin particles can be increased, and it is possible to obtain sufficiently colored resin particles in about 30 minutes to 1 hour. The stirring method may be carried out by using a commercially available stirrer such as a homomixer or a magnetic stirrer.
Further, the dye may be directly added to the slurry obtained at the end of the polymerization by dispersion polymerization or the like, that is, the dispersion liquid in which the polymerized resin particles are dispersed in the organic solvent, and the mixture may be heated and stirred under the above conditions. If the heating temperature exceeds the glass transition temperature, fusion of the resin particles will occur. The method of drying the slurry after dyeing is not particularly limited, but it may be dried under reduced pressure after filtration, or may be directly dried under reduced pressure without filtration. In the present invention, the colored particles obtained by air-drying or vacuum-drying after filtering are reproduced with almost no aggregation and without impairing the particle size distribution of the resin particles charged.

Polarity Control In order to improve the triboelectric chargeability of the toner particles produced through the dyeing process, there are the following methods of incorporating the charge control agent into the toner particles. That is, (1) by dissolving the charge control agent together with the dye in the organic solvent in the step of dyeing the resin particles, the organic solvent is removed after dyeing, and the charge control agent remains attached to the surface of the resin particles. Let (2) Alternatively, the charge control agent particles may be mechanically driven into the surface of the dried resin particles after dyeing. Moreover, you may supplementally heat at the time of driving. In this case, by setting the size of the charge control agent particles to be 1 μm or less, the charge control agent particles are firmly struck onto the surface of the resin particles so as not to be easily released particularly in the developer. Further, the ratio between the charge control agent and the colored resin particles is arbitrarily selected because the charge amount required for the toner differs depending on the developing means. Usually, 0.1 to 50 parts by weight is preferable with respect to 100 parts by weight of the colored resin particles. If it is less than 0.1 part by weight, the effect of controlling the charge is too small, and if it exceeds 50 parts by weight, the fixing property is adversely affected. As a driving method, colored resin particles and charge control agent particles are mixed in advance, and then mechanical energy is applied. The mixing method is ball mill,
Anything such as a V blender or a Henschel mixer may be used. Mechanical energy can be applied by impacting the mixture with a blade that rotates at high speed, by injecting the mixture into a high-speed air stream to accelerate the particles, and colliding the particles with each other or the mixed particles against an appropriate collision plate. Is a method of adhering and fixing a charge control agent on the surface of the colored resin particles. Specific equipment is an Ong Mill (Hosokawa Micron Co., Ltd.) and an I-type Mill (Nippon Pneumatic Mfg. Co., Ltd.) with a lower grinding air pressure than in the case of normal grinding, and a hybridization system (Nara Machinery Co., Ltd.). , Automatic mortar, etc. Specific examples of the charge control agent include the following. Nigrosine, azine dyes containing alkyl groups having 2 to 16 carbon atoms (Japanese Patent Publication No. 42-1627), basic dyes [eg CI Basic Ye
llow 2 (CI41000), CIBasic Yellow3, CIBasic R
ed 1 (CI45160), CIBasic Red 9 (CI42500), CIB
asic Violet 1 (CI42535), CIBasic Violet 3 (CI
42555), CIBasic Violet 10 (CI45170), CIBasic
Violet 14 (CI42510), CIBasic Blue 1 (CI42025)
, CIBasic Blue 3 (CI51005), CIBasic Blue 5
(CI42140), CIBasicBlue 7 (CI42595), CIBas
ic Blue 9 (CI52015), CIBasic Blue 24 (CI5203
0), CIBasic Blue 25 (CI52025), CIBasic Blue 2
6 (CI44045), CIBasic Green (CI42040), CIBasi
lake pigments of these basic dyes such as c Green 4 (CI42000), etc. (as the laking agent, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, ferricyanide, ferrocyanide Etc.), CISolvent Black 3 (CI26150), Hansa Yellow G (CI11680), CI Mordlant Black 11, CI
Pigment Black 1, benzolmethyl-hexadecyl ammonium chloride, decyl-trimethyl ammonium chloride, or dialkyltin compounds such as dibutyl or dioctyl, dialkyltin borate compounds, guanidine derivatives, vinyl polymers containing amino groups, condensation containing amino groups Polyamine resin such as polymer, JP-B-41-20153, JP-B-43-2
No. 7596, No. 443697, No. 45-26478.
Complex salts of monoazo dyes described in No. Japanese Patent Office Sho 5
No. 5-42752, JP-B-58-41508, JP-B-58-7384, and JP-B-59-7385, Zn, Al, Co, Cr of salicylic acid, dialkyl salicylic acid, naphthoic acid and dicarboxylic acid, Metal complexes such as Fe, sulfonated copper phthalocyanine pigments, etc. It is also possible to drive the following fine particles which have been atomized by means such as recrystallization, pulverization and emulsification. Fine particles having a relatively high Tg, for example, submicron fine particles of PMMA (polymethylmethacrylate), PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride).

Treatment of Release Agent Further, if necessary, a release agent such as polyolefin, fatty acid ester, fatty acid metal salt, higher alcohols, paraffin wax, etc. may be applied to the surface of the toner particles. When the implantation process is performed, the process may be performed simultaneously with the implantation of the charge control agent, or may be performed separately before and after.

Additive In the present invention, the toner particles may contain an additive. As the additive in this case, known fine particles such as titanium oxide particles, hydrophobic silica particles, zinc stearate, and magnesium stearate are used.
As a mixing method, a general mixing device such as a V blender or a ball mill may be used.

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 Base particles were produced by the dispersion polymerization method as described below. 320 g of methanol was placed in a 500 cc three-necked flask equipped with a stirring blade and a condenser, and 6.4 g of polyvinylpyrrolidone (dispersion stabilizer, average molecular weight 40,000) was added little by little with stirring to completely dissolve it. Further, the following composition was added and completely dissolved. Styrene 25.6 g n-Butyl methacrylate 6.4 g 2,2'-Azobisisobutyronitrile 0.2 g With stirring, the inside of the flask was purged with nitrogen gas and left for 1 hour. 200 rp in a constant temperature water bath of 60 ℃ ± 0.1 ℃
Polymerization was initiated while stirring at a stirring speed of m. After heating 15
When it was separated, the liquid began to become cloudy and remained a stable dispersion after 20 hours of polymerization. As a result of partially sampling and measuring by gas chromatography with the internal standard method,
It was confirmed that the polymerization rate was 93%. The resulting dispersion is cooled and centrifuged at 2000 rpm in a centrifuge,
The polymer particles were completely settled and the upper liquid was transparent.
The supernatant was removed, 200 g of methanol was added, and the mixture was washed with stirring for 1 hour. 5) Centrifuge and wash with methanol
Repeated times and passed through. The filtered product was dried under reduced pressure at 50 ° C for 24 hours, and white powder of styrene / n- was obtained with a yield of 95%.
Butyl methacrylate copolymer particles were obtained. The obtained particles have a volume average particle diameter Dv = 7.40 μm and Dv / Dp = 1.07.
(Number average particle size 6.92 μm). Also, Tg is 65 ℃
Met. (Hereinafter, this polymer particle is referred to as B.) Next,
Oil black 803 (Orient Chemical Co., Ltd.) (1.50 g) was dissolved in 200 g of methanol by heating, cooled, and filtered with a 1 μm filter to prepare a dye solution. Next, 24 g of polymer particles B were added to the filtrate to decompose it, and the mixture was heated and stirred at 50 ° C. for 1 hour. After that, the dispersion is cooled to room temperature and filtered.
Colored resin particles B were obtained by drying under reduced pressure at 50 ° C. for 24 hours. next,
After 3 parts by weight of 3,5-di-t-butylsalicylic acid zinc salt was mixed with 100 parts by weight of the colored resin particles B in an Auster blender for 10 minutes, the mixture was transferred to a hybridization system (Nara Machinery Co., Ltd.). Then, it was processed at a rotation speed of 7,000 rpm for 10 minutes. Next, 0.75 parts by weight of hydrophobic silica was added to 100 parts by weight of this toner, and mixed for 10 minutes at 2000 rpm with a Henschel mixer to obtain a toner of the present invention. On the other hand, a carrier prepared by coating ferrite particles having a particle size of 100 μm with a silicone resin in a thickness of 1 μm was mixed with the above-mentioned toner at a ratio of 3.0% by weight and stirred in a ball mill pot for 30 minutes to prepare a developer. .. Next, the Ricoh Imagio 420 was modified so that the recycled toner was returned to the toner supply tank.
Using this electrophotographic apparatus, a continuous copy test was carried out with the above-mentioned developer, and after 20,000 sheets, as shown in Table-1, no scumming and toner scattering occurred and the image quality was the same as the initial one. Was maintained. When I checked the amount of toner consumed during the copy test, A4 size 3100 sheets / 100g
Met.

Comparative Example 1 Polyvinylpyrrolidone (average molecular weight 40,000) as a dispersant
Polymerization particles were prepared by the same method as in Example 1 except that the stirring speed during polymerization was 350 rpm. The Dv of the particles was 7.5 μm and the Dv / Dp was 1.29. Next, dyeing, mixing hydrophobic silica, creating a developer,
The test with Imagio 420 was performed in exactly the same way as in Example 1. Although high image quality was obtained in the initial stage, scumming and toner scattering began to occur from about 10,000 sheets after the start of the test, and after 20,000 sheets, both scumming and toner scattering became severe. Also,
The toner consumption was also large. When the developer after 20,000 sheets was observed with a scanning electron microscope, the entire surface of the carrier was covered with toner with a small particle size, and the toner with a relatively large particle size was in direct contact with the carrier. It was in a state where I couldn't.

Comparative Example 2 Polyvinylpyrrolidone (average molecular weight 40,000) as a dispersant
Was 9.6 g, and polymerized particles were prepared by the same method as in Example 1 except that the stirring speed during polymerization was 500 rpm. The Dv of the particles was 5.2 μm and the Dv / Dp was 1.26. Next, dyeing, mixing hydrophobic silica, creating a developer,
The test with Imagio 420 was carried out in exactly the same way as in Example 1. Although high image quality was obtained in the initial stage, scumming and toner scattering started to occur from about 5,000 sheets after the start of the test.
After 10,000 sheets, both the background stain and the toner scattering became severe. Also, the toner consumption was large. When the developer after 20,000 sheets was observed with a scanning electron microscope, the entire surface of the carrier was covered with toner with a small particle size, and it seems that toner with a relatively large particle size cannot directly contact the carrier. It was in a state of.

Comparative Example 3 Styrene monomer 80 parts n-Butyl acrylate monomer 20 parts Chromium-containing azo dye 3 parts Carbon black MA100 10 parts (manufactured by Mitsubishi Kasei) The above polymerizable monomer mixture was dispersed and mixed for 12 hours using a ball mill. After that, 1.5 parts of azobisisobutylnitrile was dissolved in this dispersion. On the other hand, potassium iodide
0.3 parts, polyvinyl alcohol 8.0 parts with ion-exchanged water 4
It was dissolved in 00 parts to prepare an aqueous medium. TK homomixer (made by Tokushu Kika Kogyo Co., Ltd.)
And stirred at 8000 rpm for 10 hours. This suspension dispersion was transferred to a 4-neck separable flask, and under a nitrogen atmosphere,
Polymerization was carried out at a rotation speed of 90 rpm and a temperature of 70 ° C. for 6 hours. After the completion of the polymerization, the produced toner particles were repeatedly washed and filtered to be collected and dried. The volume average particle diameter Dv of this toner is 6.3 μm.
m, and the number average particle diameter Dp was 3.6 μm. (Dv / D
p = 1.75) With respect to this toner, classification is repeated to cut fine powder so that the volume average particle diameter Dv is 7.6 μm and Dv / Dp =
1.11 toner is obtained. Further, 0.75 parts by weight of hydrophobic silica was added to 100 parts by weight of this toner and mixed under the same conditions as in Example 1 to obtain a toner. For this toner,
Using the same carrier as in Example 1, a developer is prepared,
A continuous copy test using recycled toner was carried out with a modified machine of Imagio 420. Although an image free of background stains was obtained in the initial stage, background stains began to occur from about 5,000 sheets after the start of the test and gradually became worse, and after 20,000 sheets, both the sharpness and the resolution were deteriorated.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

(1) According to the developing method of the present invention, it is possible to provide an electrophotographic developing method using a recycled toner which does not cause scumming and toner scattering. (2) An electrophotographic developing method using a small particle size toner, which has excellent resolution, sharpness, and reproducibility of a halftone, and has little change in image quality and developer physical properties even when used for a long time. Became possible.

Claims (1)

[Claims] 1. An electrostatic latent image on an image carrier is developed, a toner image is transferred to a transfer paper, and the toner remaining on the image carrier is cleaned, and then this toner is used for a developing device or a replenisher. In the dry two-component developing method in which the resin particles are returned to the toner and reused, the resin particles obtained by polymerizing the polymerizable monomer are used as a matrix, and the volume average particle diameter (Dv) and the number average particle diameter of the resin particles are used. The ratio of (Dp) is 1.00 ≦ (Dv / Dp) ≦ 1.
An electrophotographic developing method characterized in that a toner having a Dv of 1 to 20 μm in a range of 20 is used.