JPH0820766B2 - Toner for developing electrostatic latent image and manufacturing method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic latent image and a method for producing the same, and more specifically, it is excellent not only in environmental stability and copying performance but also in blade cleaning property. And a method for producing such a toner.

2. Description of the Related Art Conventionally, a developer of an electrostatic latent image for electrophotographic copying, that is, a toner, generally imparts a coloring agent such as carbon black to a melted thermoplastic resin and imparts a required triboelectric chargeability to the toner. Charge control agent particles for, kneading wax for imparting offset resistance, etc., dispersed, and after cooling,
It is manufactured by finely pulverizing to a required particle size using a jet mill or the like and classifying.

According to this method, as described above, it is necessary that the resin mixture containing the colorant or the like is brittle so that it can be easily crushed, but on the other hand, when a resin that is excessively crushed is used, it was obtained. The toner is pulverized in the copying machine, causing contamination inside the machine and fogging of images. On the other hand, when a resin that is easily melted is used, filming occurs on the surface of the photoconductor, or toner particles are fused to each other, resulting in a decrease in fluidity.

In particular, in order that each toner particle has a uniform charging characteristic and a high quality copy image can be formed, a colorant and a charge control agent must be uniformly and finely dispersed in each toner particle. is important. However, when the above-mentioned conventional pulverization method is used, since the colorant particles and the charge control agent particles have a wide particle size distribution and are non-uniformly dispersed, scumming occurs in the copied image or the above-mentioned in-machine Contamination and image fogging also occur. Among them, most of the charge control agent particles that have been conventionally used, which have an important influence on the toner copying performance, usually have a particle size of 1 to 20 μm and are long to be dispersed in the resin. Not only is it time-consuming and inferior in productivity, but even when kneading for a long time, it is not easy to uniformly disperse the resin in the resin.

As described above, since the conventional so-called pulverization toner has various drawbacks, in recent years, a polymerizable monomer containing a colorant has been emulsified in water in a fine particle form so as to have a required toner particle size. After that, various methods have been proposed for directly producing a toner by subjecting this to suspension polymerization or emulsion polymerization.

In the production of toner by suspension polymerization or emulsion polymerization of such conventional polymerizable monomers, a suspension stabilizer such as polyvinyl alcohol is dissolved and contained in water, and a monomer oil phase is polymerized in the water. ing.

Therefore, the toner obtained by such a method has a suspension stabilizer remaining on the surface thereof, so that it has high humidity sensitivity, that is, high sensitivity to humidity, poor environmental stability, and charging performance. When the electrostatic latent image is developed, a non-charged toner or a reversely charged toner is generated, and thus an image is smeared or fogged or the image density is lowered.

Further, since the toner produced by the suspension polymerization or emulsion polymerization of the conventional polymerizable monomer has substantially spherical particles and has excellent fluidity, a fluidizing agent such as silica is added. However, on the other hand, it is inferior in cleaning property by a blade in electrophotographic copying.

That is, according to an electrostatic electrophotographic copying machine using plain paper as a recording paper, generally, an electrostatic charge is applied to the surface of a photoreceptor by discharge, and an image is exposed on the electrostatic charge to form an electrostatic latent image.
Next, the toner having the opposite polarity is attached to the electrostatic latent image to develop it, the toner image is transferred to the recording paper, and finally, the recording paper on which the toner image is transferred is heated to transfer the toner onto the recording paper. Copying is performed by fixing the image on. Therefore, in order to sequentially perform copying on a plurality of recording sheets, it is necessary to remove the toner remaining on the surface of the photoconductor in the above process after transferring the toner image from the photoconductor to the recording paper. As one of the removing methods, a blade cleaning method is known in which a photosensitive member is rubbed to remove toner from the photosensitive member. Various rubbers have been conventionally used as the material of the blade for this blade cleaning method, but urethane rubber is preferably used because of its excellent mechanical strength such as abrasion resistance. .

In cleaning with such a blade, when the toner is a true sphere, when the blade rubs against the surface of the photoconductor, the toner sneaks under the blade and rotates with the photoconductor surface, so to speak. In order to slip through the blade, it remains on the photoconductor even after rubbing with the blade,
It seems that it is difficult to clean.

Therefore, for example, in JP-A-62-266560, in the production of a toner by suspension polymerization, substantially spherical polymer particles are agitated in a suspension polymerization medium at high speed before the completion of the polymerization. A fixed form method has been proposed.

However, according to this method, under high temperature conditions in which the polymer particles are likely to be deformed, they are easily fused to each other due to the influence of unreacted monomers remaining in the reaction system, or the surface tension of the polymer particles is increased. Therefore, since the particles are likely to return to a spherical shape, they are difficult to be deformed. On the other hand, even if the mixture is stirred at a low speed to avoid such fusion or at a low temperature, the polymer particles are unlikely to be deformed. Further, in the production of a toner by the suspension polymerization method, toner particles have a particle size distribution, and even if large particles are relatively easily deformed, small particles are difficult to be deformed, and the degree of particle deformation is also large. Distribution occurs,
Moreover, in the cleaning with the blade, the particles having a small particle size and difficult to be deformed are, as described above,
Easy to slip through the blade.

As described above, according to the method in which the polymer particles are stirred at a high speed before the completion of the suspension polymerization, the toner is not sufficiently deformed and the obtained toner is not sufficiently improved in the blade cleaning property.

On the other hand, recently, a method for producing a toner, in which fine particles are adhered and fixed on the surface of the toner particles by a so-called air impact method, has been proposed, for example, in JP-A-62-129866. However, according to this method, in order to immobilize fine particles on each of the polymer particles having a distribution in particle size,
It is necessary to use fine particles having a particle size of 1 μm or less. On the other hand, however, even if the fine particles having a particle size of 1 μm or less are immobilized on the polymer, the blade cleaning property is slightly improved. Nothing more.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention has been made in order to solve the above-mentioned various problems in the conventional toner production, and in particular, the toner particles are deformed to improve the blade cleaning property. In addition, carbon black and charge control agent particles are uniformly and finely dispersed in each toner particle, and the harmful effect of the suspension stabilizer used for suspension polymerization of the monomer is removed. And thus,
It is an object of the present invention to provide a high-performance electrostatic latent image developing toner excellent not only in environmental stability and copying performance but also in cleaning blade property, and a method for producing such a toner.

Means for Solving the Problems The electrostatic latent image developing toner according to the present invention comprises substantially spherical polymer particles obtained by suspension polymerization of a radically polymerizable monomer oil phase in an aqueous phase. It has a modified shape and a diameter of 3 to 30 μm.
It is characterized by having a disk-like shape having a thickness of 1 to 15 μm and a flatness defined by an average thickness / average diameter of 0.5 or less.

Further, another electrostatic latent image developing toner according to the present invention is obtained by deforming substantially spherical polymer particles obtained by suspension polymerization of a radically polymerizable monomer oil phase in an aqueous phase. Oval with a major axis of 3 to 30 μm, a minor axis of 1 to 25 μm, and a thickness of 0.5 to 15 μm, and a flatness defined by 2 × average thickness / (average major axis + average minor axis) is 0.5 or less. It is characterized by having a shape.

According to the present invention, the toner according to the present invention is obtained by suspending a monomer oil phase containing carbon black and particles of a charge control agent in an aqueous phase and polymerizing the monomer to obtain a particle size of 1 to 1.
Spherical polymer particles of 30 μm were obtained, and the suspension containing the spherical polymer particles was subjected to an Aniler-type continuous wet stirring mill at a temperature within the range of ± 10 ° C. of the glass transition point of the matrix resin of the polymer particles. Treated with a diameter of 3-30 μm and a thickness of 1-15 μ
m is a disk shape having a flatness defined by the average thickness / average diameter of 0.5 or less, or a major axis of 3 to 30.
To have an oval shape with a flatness of 0.5 or less, a minor axis of 1 to 25 µm, a thickness of 0.5 to 15 µm, and a flatness defined by 2 x average thickness / (average major axis + average minor axis) of 0.5 or less. Can be obtained by

In particular, according to the present invention, in the toner as described above, (a) both the carbon black and the charge control agent particles are finely and uniformly dispersed in the form of fine particles having a particle size of 1 μm or less in the radical polymerizable monomer. Step (b) After adding an azobis-based polymerization initiator to the radical-polymerizable monomer, suspending it in an aqueous phase containing polyvinyl alcohol as a suspension stabilizer to polymerize the monomer,
A step of obtaining spherical polymer particles having a particle size of 1 to 30 μm, (c) a suspension containing the above polymer particles in an Aniler continuous wet stirring mill in the presence of polyvinyl alcohol, and a matrix resin of the following polymer particles. Of glass transition point of
Treated at a temperature of 10 ℃, diameter 3-30μm, thickness 1-15μ
m is a disk shape having a flatness defined by the average thickness / average diameter of 0.5 or less, or a major axis of 3 to 30.
μm, minor axis 1 to 25 μm, thickness 0.5 to 15 μm, and deforming into an oval shape having a flatness of 0.5 or less defined by 2 × average thickness / (average major axis + average minor axis). , (D) a step of saponifying the polyvinyl alcohol, and (e) a step of collecting, washing, drying and, if necessary, classifying the polymer particles, can be advantageously produced. .

In the present invention, the radical-polymerizable monomer is not particularly limited, and generally, any monomer used in the production of toner by a conventional polymerization method can be used. Examples of such a monomer include styrene, o-methylstyrene, m-methylstyrene, p-
Methylstyrene, p-chlorostyrene, vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, acrylic acid 2 -Ethylhexyl, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-methacrylate. Octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate,
Acrylonitrile, methacrylonitrile, acrylamide, glycidyl acrylate, glycidyl methacrylate,
Acrylic acid, methacrylic acid, 2-vinyl pyridine, 4-
Vinyl pyridine etc. can be mentioned.

However, in the present invention, among these monomers, styrene and a mixture of styrene and an acrylic acid ester or a methacrylic acid ester are particularly preferably used.

Further, in the present invention, the radical-polymerizable monomer may contain a small amount of a polyfunctional monomer in order to improve the fixing property and the offset resistance of the toner. Examples of such polyfunctional monomers include divinylbenzene and ethylene glycol dimethacrylate. When such polyfunctional monomer is used in too much amount,
The resulting polymer particles are less likely to be heated and melted, resulting in poor fixability as a toner. Therefore, it is usually used in an amount of about 1% by weight or less of the radical-polymerizable monomer.

In the method of the present invention, first, both carbon black as a colorant and particles of the charge control agent are dispersed in the monomer in the form of fine particles having a particle size of 1 μm or less.

In the present invention, in order to uniformly and finely disperse the carbon black in the monomer, it is preferable to stir the carbon black with the monomer in the presence of the peroxide type polymerization initiator using a ball mill or the like. As such a peroxide-based polymerization initiator, for example, benzoyl peroxide, lauryl peroxide, o-chlorobenzoyl peroxide, o-methoxybenzoyl peroxide, etc. are used, but lauryl peroxide is particularly preferably used.

Usually, the radical-polymerizable monomer and the carbon black are stirred for several hours in the presence of the peroxide-based polymerization initiator as described above to give carbon black particles of 1 μm or less, preferably 0.5 μm or less. It can be evenly dispersed in the monomer in diameter. This distributed processing is
It may be carried out at a temperature of 50 to 80 ° C. in order to accelerate the dispersion speed of carbon black in the monomer.

In the present invention, the carbon black is used in the range of 2 to 10 parts by weight with respect to 100 parts by weight of the radical-polymerizable monomer.

In dispersing the carbon black in the monomer as described above, the peroxide-based polymerization initiator is usually used in the range of 10 to 50 parts by weight, preferably 10 to 40 parts by weight with respect to 100 parts by weight of the carbon black. To be With respect to 100 parts by weight of carbon black, when the amount of the peroxide-based polymerization initiator is less than 10 parts by weight, the carbon black cannot be finely and uniformly dispersed in the monomer, while 50 parts by weight is added. If it exceeds the above range, decomposed fragments of the polymerization initiator remain in the obtained toner, resulting in an offensive odor during heat fixing of the toner, which is not preferable in practice.

When dispersing the carbon black in the monomer,
When an azobis-based polymerization initiator such as azobisbutyronitrile or azobisdimethylvaleronitrile is used instead of the peroxide-based polymerization initiator, the carbon black is finely and uniformly dispersed in the monomer. It cannot be allowed to do so and the carbon black aggregates with each other and is mostly dispersed in the monomer while still forming large particles.
Further, since the monomer is partially polymerized, the viscosity of the monomer containing carbon black increases. Such an increase in the viscosity of the monomer acts detrimentally when forming minute oil droplets of the monomer in water.

When dispersing the carbon black in the radical polymerizable monomer in the presence of a peroxide type polymerization initiator,
A carbon black and a peroxide-based polymerization initiator are simultaneously added to the monomer, and this may be dispersed in the monomer by using a ball mill or the like, or by using a ball mill or the like. After the carbon black is preliminarily dispersed in the monomer, the peroxide-based polymerization initiator may be dissolved in this and stirred.

In the present invention, as the colorant, if necessary, other various black and white or chromatic color pigments and dyes can be used together with the above carbon black. These colorants may or may not be soluble in the monomer oil phase. Specific examples of such colorants are described in, for example, JP-A-62-246073. When using a colorant that does not dissolve in the monomer oil phase, in the same manner as when using a carbon black, by using a peroxide-based polymerization initiator and other suitable dispersants,
It can be finely and uniformly dispersed.

Next, according to the method of the present invention, the charge control agent particles are uniformly and finely dispersed in the monomer oil phase in which the carbon black is dispersed as described above. For this purpose, the following method is preferably used. That is, a dispersant soluble in the monomer is added to the monomer together with the charge control agent particles in the monomer oil phase in which the carbon black is dispersed, and the dispersant is dissolved in the monomer. For example, in a ball mill,
Stir for 50-200 hours. By this method, the charge control agent particles can be uniformly dispersed in the monomer with a particle size of about 0.5 μm or less, preferably about 0.3 μm.
This dispersion treatment may also be performed at a temperature of 50 to 80 ° C. in order to accelerate the dispersion speed of the charge control agent particles in the monomer.

The charge control agent particles are usually a radically polymerizable monomer 100.
About 0.01 to 10 parts by weight, preferably about 0.05 parts by weight.
~ 5 parts by weight, most preferably about 0.1 to 1 part by weight.

In the present invention, as the charge control agent particles, at least one selected from an inorganic compound powder, a metal-containing pigment and an organic compound powder containing an organic acid metal salt, and an organic polymer powder is used.

Examples of the inorganic compound powder as the charge control agent particles include a nitride containing an inorganic pigment, a carbide, an oxide, a sulfate, a carbonate, a titanate, a phosphate, a silicate, and a hexafluorosilicate. be able to. Specific examples include, for example, nitrides such as boron nitride, titanium carbide, tungsten carbide, zirconium carbide, boron carbide, carbides such as silicon carbide, silicon dioxide (silica), chromium oxide, cerium oxide, zirconium oxide, titanium oxide, Oxides of magnesium oxide, aluminum oxide, copper oxide, nickel oxide, zinc oxide, etc., strontium sulfate, barium sulfate, calcium sulfate, aluminum sulfate, magnesium sulfate, sulfates such as copper sulfate, carbonates such as calcium carbonate, magnesium carbonate, etc. , Phosphates such as calcium phosphate, zirconium, copper, cobalt, nickel, magnesium,
Calcium, strontium, barium, aluminum, zinc and other silicates, sodium, potassium, magnesium, calcium, strontium, barium, zinc, aluminum and other hexafluorosilicates, and other emery, alundum, garnet, corundum, lime, Examples thereof include tripoly, roxsite, halite, bentonite, molybdic acid chelate pigments and acid clay.

If necessary, such an inorganic compound powder may be hydrophobized with a silane coupling agent or a titanium coupling agent in advance. The coupling agent used for this purpose, in consideration of the chargeability of the intended toner, when a negatively chargeable toner is obtained, a coupling agent having a chlorine group that is easily negatively charged, such as dichlorosilane, is used.
To obtain a positively chargeable toner, a coupling agent having an amino group that is easily positively charged, such as aminosilane, is used. Such a coupling agent is appropriately selected from the above-mentioned coupling agents.

The organic compound powder as the charge control agent particles contains a metal-containing dye / pigment and an organic acid metal salt, and in particular, various organic compounds known as charge control agents are preferably used. As the positive charge control agent, for example, the following formula (X ⁻ represents an anion species.) An electron donating dye such as a nigrosine dye represented by
Alkoxylated amines, alkylamides, quaternary ammonium salts and the like can be mentioned. On the other hand, examples of the negative charge control agent include: (In the formula, X ⁺ represents a cation species.) (In the formula, X ⁺ represents a cation species.) (“Spilon Black TRH” (Hodogaya Chemical Co., Ltd.)
Electron accepting dyes such as metal complex salts of monoazo dyes represented by

Further, in addition to the above, sulfonylamine of copper phthalocyanine, oil black, metal salt of naphthenic acid, metal salt of fatty acid such as zinc stearate, resin acid soap and the like can be mentioned.

Further, the organic polymer powder as the charge control agent particles is also selected in consideration of the chargeability of the intended toner. In the case of obtaining a negatively chargeable toner, a polymer which is easily negatively charged, for example, a homopolymer or a copolymer of styrene having an aromatic nucleus as an electron-withdrawing group and its dielectric, for example, polystyrene, styrene-butyl acrylate copolymer Polymers, styrene-2-ethylhexyl acrylate copolymers, styrene-butyl methacrylate copolymers, polymers containing halogen atoms such as fluorine and chlorine, such as polyvinyl chloride, are used. On the other hand, when a positively chargeable toner is obtained, a polymer which is easily positively charged, such as polymethyl methacrylate, polybutyl methacrylate, polyamide having an electron donating group, is used.

These organic polymer powders used in the present invention are preferably produced by so-called emulsifier-free emulsion polymerization so as not to contain a surfactant. However, for example, even a polymer powder obtained by emulsion polymerization can be used after removing the emulsifier.

In the present invention, the above charge control agent particles may be used as one kind or as a mixture of two kinds.

The dispersant used to disperse the charge control agent particles in the monomer may be a low molecular weight substance or a high molecular weight substance. Examples of the low molecular weight dispersant include a surfactant, a silane coupling agent, a titanium coupling agent, and an oligomer having an isocyanate group or an epoxy group.

More specifically, as the surfactant, for example, fatty acid salt, alkyl sulfate ester, alkyl benzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate ester salt, alkyl phosphate ester salt, naphthalene sulfonate formalin condensate. , Anionic surfactants such as polyoxyethylene alkyl sulfate, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid Nonionic surfactants such as esters and oxyethyleneoxypropylene block polymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. Door can be.

The silane coupling agent, for example, γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ
-Mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-ureidopropyltriethoxysilane, 3,3,4,4,5,5,6,6,6-nonafluorohexyltrichlorosilane, 3,3 , 4,4,5,5,6,6,6-nonafluorohexylmethyldichlorosilane and the like can be mentioned. Further, as the reactive silane, for example, methyltrimethoxysilane, phenyltrimethoxysilane,
Examples thereof include methylphenyldimethoxysilane and diphenyldimethoxysilane.

Titanium coupling agents include, for example, isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethylaminoethyl) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, tetra- 2,2-Diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl Isostearoyl titanate, isopropyl tridecylbenzene sulfonyl titanate, isopropyl isostearoyl diacrylic titanate, Sopuropirutori (dioctyl phosphine benzoate) titanate, isopropyl tricumyl phenylalanine titanate, it can be given tetraisopropyl bis (dioctyl male phosphite) titanate.

Further, as the high molecular weight dispersant, various polymers and copolymers having a functional group are preferable, for example, a carboxyl group, a sulfone group, a hydroxyl group, a halogen group, an epoxy group,
Examples thereof include polymers and copolymers having a cyano group, a nitrile group, a butyral group, an ester group, a carbonyl group, an amino group or the like as a functional group.

More specifically, as the polymer or copolymer,
For example, styrene-acrylic acid copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-
Methacrylic acid copolymer, styrene-methacrylic acid-2-
Hydroxyethyl copolymer, styrene-acrylonitrile copolymer, styrene-glycidyl methacrylate copolymer, methyl methacrylate-acrylic acid copolymer, methyl methacrylate-dimethylaminoethyl methacrylate copolymer, methyl methacrylate-methacrylic acid Acid copolymer, methyl methacrylate-methacrylic acid-2-hydroxyethyl copolymer, methyl methacrylate-acrylonitrile copolymer, methacrylic acid-glycidyl methacrylate copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride -Vinyl acetate-vinyl alcohol copolymer, polyvinyl butyral, vinylidene chloride-acrylonitrile copolymer,
Acrylonitrile-butyl acrylate-2-hydroxyethyl methacrylate copolymer, ethylene-vinyl acetate copolymer, polyvinyl acetate, vinyl-based (co) polymers such as partially sulfonated polystyrene, and rubber such as acrylonitrile-butadiene copolymer Polymer, nitrocellulose,
Examples thereof include fibrin-based polymers such as acetyl cellulose, crosslinkable resins such as epoxy resins, phenoxy resins and urethane resins. These polymers may be used alone or in 2
Used as a mixture of two or more species.

In particular, in the present invention, as the dispersant, those having a functional group having a strong interaction with the charge control agent used are preferably used. For example, when an electron-accepting dye such as a metal complex salt of a monoazo dye that imparts negative chargeability or an electron-accepting organic complex is used as the charge control agent, the dispersant may be, for example, partially saponified polyvinyl acetate. , Styrene-
Acrylic acid copolymers, ethylene-vinyl acetate copolymers and the like are preferably used.

In dispersing the charge control agent in the radical-polymerizable monomer, the dispersant described above varies depending on the particle size of the charge control agent powder used, but is usually 1 to 100 parts by weight per 100 parts by weight of the charge control agent. , Preferably in the range of 10 to 50 parts by weight. If too much dispersant is used,
The viscosity of the mixture during the dispersion operation becomes high, and it becomes difficult to make the charge control agent finer. On the other hand, when it is too small, the effect of dispersing the charge control agent is poor.

Also in the dispersion of this charge control agent in the monomer, as in the case of the carbon black described above, after preliminarily dispersing the charge control agent in the monomer using a ball mill or the like, The dispersant may be dissolved in and stirred.
Of course, the dispersant and the charge control agent are simultaneously added to the monomer,
This may be mixed by stirring using a ball mill or the like.

Depending on the charge control agent to be used, some charge control agents have a function of inhibiting undesired polymerization in the aqueous phase in suspension polymerization of the monomer oil phase described later. For example, "Spiron Black TRH" described later is such an example. Apart from its original purpose, such a charge control agent may be dispersed mainly in the monomer oil phase as a polymerization inhibitor in the aqueous phase.

According to the method of the present invention, as described above, both the carbon black and the charge control agent particles in the monomer have a particle size of 1 μm.
After finely and uniformly dispersing into the following fine particles, if necessary, additional required monomers are further added to this dispersion, or in order to impart offset resistance to the obtained toner. With the addition of wax and the like, an azobis-based polymerization initiator is added again as a polymerization initiator. As the azobis-based polymerization initiator, azobisdimethylvaleronitrile, azobisisobutyronitrile and the like are used, and particularly oil-soluble azobisdimethylvaleronitrile is preferably used.

Here, without adding a new azobis-based polymerization initiator, an oily dispersion comprising a carbon black and a monomer is dispersed as fine oil droplets in water using a homogenizer, etc. Polymerization of the polymer hardly occurs.
That is, since the peroxide-based polymerization initiator added to the monomer when dispersing the carbon black in the monomer, most are decomposed in the process of dispersing the carbon black,
In the present invention, it is necessary to newly add a polymerization initiator at the stage of polymerization, and the polymerization initiator newly added here must be an azobis type, not a peroxide polymerization initiator. Even if a peroxide-based polymerization initiator is newly added at the polymerization stage, the monomer is hardly polymerized, or even if polymerized, the resulting polymer has a low molecular weight and a toner excellent in offset resistance is obtained. I can't.

In the method of the present invention, the amount of the azobis polymerization initiator is in the range of 1 to 10 parts by weight, preferably 2 to 5 parts by weight, based on 100 parts by weight of the monomer. When the addition amount of the azobis polymerization initiator is less than 1 part by weight with respect to 100 parts by weight of the monomer, the polymerization rate of the monomer is low and the polymerization rate is low.
It is difficult to polymerize at 100%. On the other hand, the addition amount of the azobis-based polymerization initiator is 1 with respect to 100 parts by weight of the monomer.
If the amount is more than 0 parts by weight, the resulting polymer has a low molecular weight and the toner is inferior in offset resistance, which is not preferable.

Then, according to the method of the present invention, a carbon black,
An oily mixture containing charge control agent particles, an azobis-based polymerization initiator and a monomer is mixed with water, and this is stirred by, for example, a homogenizer or the like, and the particle size of the oily mixture is 1 to 30 μm.
An aqueous suspension containing m droplets is obtained.

In the present invention, the water mixed with the oily mixture preferably contains polyvinyl alcohol as a suspension stabilizer. Polyvinyl alcohol used as a suspension stabilizer usually has an average degree of polymerization of 500 to 3000 and a degree of saponification of about 80 to 99 mol%. The amount of polyvinyl alcohol in this water is usually 0.1 to 5% by weight.
Further, in order to prevent polymerization in the aqueous phase, water-soluble inorganic salts such as sodium chloride, sodium sulfate, aluminum sulfate and the like may be contained.

The aqueous suspension thus obtained is stirred at a temperature of 40 to 95 ° C., preferably about 50 to 90 ° C. to polymerize the radically polymerizable monomer to obtain a particle size of 1 ~ 30μ
m to produce substantially spherical polymer particles. In the substantially spherical polymer particles, the flatness described later is usually 0.98 or more.

Then, in the method of the present invention, a suspension containing such substantially spherical polymer particles is prepared, and then the suspension is added in the presence of polyvinyl alcohol as the suspension stabilizer to an Aniular type. In a continuous wet agitation mill, the polymer particles are treated at a temperature within the range of ± 10 ° C. of the glass transition point of the matrix resin to form a disc or oval shape.

The above-mentioned Anyurer type continuous wet agitation mill is one of the known mills, and as shown in FIG. 1, a rotor having substantially the same shape in an Annular type (annular) stator 1 having a triangular cross section. 2 is rotated, and the narrow gap between the stator and the rotor, that is, the crushing zone 3 is filled with the medium 4, and the suspended particles supplied to the mill are mechanically impacted, This is flattened.

The suspension circulates through the crushing zone 3 having a W-shaped cross section by a pump from a supply port 5 in the lower part of the mill, is separated from the media by a cap separator 6 in the upper part, and the polymer particles deformed from the outlet 7 are deformed. A suspension containing can be obtained. Further, the temperature control of the suspension liquid during the deformation treatment is performed by circulating the hot water 8 through the stator and the rotor. The crushing media sequentially moves in the W-shaped crushing zone by centrifugal force, returns to the crushing inlet again, and circulates. As the crushed media, zircon, glass, steel or the like having a diameter of 0.5 to 3 mm is usually used.

The treatment of the suspension using such an Aniler-type continuous wet stirring mill needs to be performed at a temperature within the range of ± 10 ° C. of the glass transition point of the matrix resin of the polymer particles. When the treatment is carried out at a temperature lower than (glass transition point -10) ° C, the polymer particles are crushed, and it becomes difficult to carry out the desired modification. On the other hand, (glass transition point +
10) When treated at a temperature higher than 0 ° C, the polymer particles are fused with each other to form agglomerates, and the deformed polymer particles are again made spherical by the surface tension. Therefore, the deforming efficiency is poor. The treatment time is usually 0.5 to 10 hours, preferably 2 to 5 hours.

When an Aniler-type continuous wet agitation mill is used, a larger shearing force acts in the rotational direction of the rotor as compared with a ball mill, a sand mill, etc., so that stress in different directions is applied to the toner and even if the toner has a particle size distribution. , Can be efficiently flattened. Therefore, the obtained toner is flattened regardless of the particle size, so that the blade cleaning property is remarkably improved. Further, since such a flattened toner has a large contact area with paper, it can be fixed at a low temperature and a low pressure as compared with a true spherical or egg-shaped toner. Further, according to the toner of the present invention,
Since the particle shape is flat and a single particle of the toner occupies a large area on the copied image, the image density can be increased with a small amount, and thus the toner consumption can be reduced.

Thus, according to the present invention, a diameter of 3 to 30 μm and a thickness of 1 to
It has a disk-like shape having a flatness of 15 μm and a flatness defined by the average thickness / average diameter of 0.5 or less, or a long diameter of 3 to 30 μm, a short diameter of 1 to 25 μm, and a thickness of 0.5 to 15 μm.
Moreover, it is possible to obtain the modified polymer particles having an oval shape having a flatness defined by 2 × average thickness / (average major axis + average minor axis) of 0.5 or less.

Next, in the method of the present invention, polyvinyl alcohol serving as the suspension stabilizer is saponified after the modification treatment. Here, saponification of polyvinyl alcohol may be carried out by adding a saponification reagent to a suspension containing polymer particles, and the polymer particles may be separated and recovered from the suspension, and the saponification reagent may be added thereto. May be performed.

The saponification is performed using an alkali or an acid.
In the case of alkali saponification, the amount of alkali is sufficient if it is about 1000 times equivalent, preferably 5 to 50 times equivalent to the amount of vinyl acetate in the polyvinyl alcohol used as the suspension stabilizer. If necessary, the minimum amount of alkali required can be determined by simple experimentation. As the alkali, for example, sodium hydroxide or potassium hydroxide is preferably used.

Saponification of polyvinyl alcohol is carried out, for example, with such an alkali, water, and 1 to 50% by volume thereof, preferably 5%.
~ 30% by volume of a lower aliphatic alcohol, such as methanol, ethanol, propanol, preferably a mixture with methanol, is added, but not limited to,
It can be carried out by heating at a temperature of 40 to 70 ° C. for about 1 to 10 hours. However, the saponification condition is not limited to this.

In the alkali saponification of polyvinyl alcohol, the use of a lower aliphatic alcohol such as methanol enhances the wettability of the surface of the spherical polymer particles with water, which is advantageous in that the saponification can be carried out quickly and smoothly. Furthermore,
For example, saponification of polyvinyl alcohol in the presence of methanol has an advantage that the saponification reaction is rapidly performed in the form of ester conversion in which a vinyl acetate unit in polyvinyl alcohol reacts with methanol to generate methyl acetate. .

In this way, after saponifying the polyvinyl alcohol remaining on the polymer particles, the polymer particles are separated, washed with water or the same lower aliphatic alcohol aqueous solution as described above, preferably an aqueous methanol solution, and then, such as hydrochloric acid. The alkali metal hydroxide used is neutralized by washing with an aqueous solution containing an acid or an aqueous methanol solution, and further washed with water or an aqueous methanol solution.

The aqueous alcohol solution used for washing the polymer particles after saponification of the polyvinyl alcohol is not particularly limited, but water and its alcohol, preferably methanol, 1 to 50% by volume, preferably 5 to 30% by volume. % Is preferred. The acid for neutralizing the alkali metal hydroxide may be used in an equivalent amount with respect to the alkali metal hydroxide used, and the same alcohol aqueous solution containing the acid is preferably used. Further, for the washing of the polymer particles after the neutralization, a mixture of water and its alcohol of 1 to 50% by volume, preferably about 5 to 30% by volume, preferably methanol, is preferably used.

In the present invention, polyvinyl alcohol as a suspension stabilizer may be saponified with an acid. in this case,
After the suspension polymerization as described above, for example, a mixture of water containing an inorganic acid such as sulfuric acid and an alcohol, preferably methanol, is added, and the mixture is heated and then neutralized with an alkali to obtain the obtained heavy polymer. The coalesced particles are washed with water.

Thus, after saponifying the polyvinyl alcohol, the polymer particles are washed and dried, collected, and if necessary classified, the toner according to the present invention can be obtained.

In the method of the present invention, spherical polymer particles having a particle size of 1 to 30 μm are thus prepared by suspension polymerization of the monomer, and the spherical polymer particles are deformed and then left on the polymer particles. The polyvinyl alcohol to be saponified and washed to remove the polyvinyl alcohol from the polymer particles, so that the moisture sensitivity in the toner based on polyvinyl alcohol is removed,
The environmental stability of the toner can be improved. Moreover, according to the present invention, since the toner is modified, the blade cleaning property is excellent. Thus, according to the present invention, not only the environmental stability and the copying performance are excellent,
A toner having excellent blade cleaning property can be obtained.

Since the toner according to the present invention is thus modified, in order to enhance its fluidity, a so-called fluidity improving agent such as hydrophobic silica may be further added to the toner, if necessary. Good. Such a fluidity improver is usually used in an amount of 0.05 to 1 part by weight, preferably 0.1 to 100 parts by weight of the toner.
It is compounded in the range of 0.5 to 0.5 parts by weight.

The toner according to the present invention may be a one-component magnetic toner or a one-component non-magnetic toner, as well as a two-component toner.

In the production of magnetic toner, as the magnetic material, for example, ferrite such as ferric tetroxide, magnetic oxide such as magnetite, or various magnetic metals are used. These magnetic materials are usually used in an amount of 30 to 300 parts by weight, preferably 30 to 100 parts by weight, based on 100 parts by weight of the monomer. Such a magnetic material is previously dispersed in a monomer by using an appropriate mixing / dispersing means such as a ball mill,
Thereafter, according to the present invention, it is preferable to disperse the carbon black and the charge control agent in the monomer.

When the toner according to the present invention is used in a two-component developing system, a substance known as a carrier, which is well known in the technical field of electrostatic electrophotography, is added and used as a two-component developer. In this two-component developer, the amount of toner blended is in the range of 2 to 20% by weight, preferably 5 to 10% by weight. As the carrier, for example, iron powder, ferrite powder, powder composed of a composite of resin and magnetic material,
Magnetite powder or the like is used. Also, a so-called coat carrier can be used. However, it is not limited to these.

As described above, according to the present invention, the spherical polymer particles obtained by subjecting the spherical polymer particles obtained by suspension polymerization to the radical polymerization monomer in which the carbon black and the charge control agent particles are finely and uniformly dispersed are disc-shaped. After deforming into a shape or an oval shape, the polyvinyl alcohol used at the time of suspension polymerization of the above-mentioned monomer and at the time of deforming is removed by saponification. Therefore, in the obtained toner particles, the carbon black and the charge control agent particles are finely and uniformly dispersed and excellent in environmental stability. Thus, the toner according to the present invention is excellent in environmental stability and copying performance. In addition to being excellent in blade cleaning property and fixing property at low temperature and low pressure, toner consumption can be reduced.

EXAMPLES The present invention will be described below with reference to examples of producing a two-component non-magnetic toner, but the present invention is not limited to these examples.

Example 1 50 parts by weight of styrene, 1 part by weight of lauryl peroxide and carbon black ("Dia Black"# 52 (manufactured by Mitsubishi Kasei Co., Ltd., volatile content 0.8%, pH 8.0, particle size 27 mμ) 5.0
Parts by weight were added, and mixed by a ball mill for 30 minutes to disperse the carbon black in styrene. The resulting mixture was then stirred in an autoclave at 70 ° C for 1 hour.
After this dispersion treatment, the carbon black had a particle size of about 0.1 μm in the monomer, and no precipitation was observed.

Next, 0.4 part by weight of ethylene-vinyl acetate copolymer (Soavelen CH manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) as a dispersant was dissolved in the mixture thus obtained, and then, as a negative charge control agent. Dye "Spyron Black TR
H ”(manufactured by Hodogaya Chemical Co., Ltd.) was added and mixed in a ball mill for 100 hours to disperse the above charge control agent in styrene. After this dispersion treatment, the charge control agent had a particle size of about 0.3 μm, and no sedimentation of the charge control agent was observed in the monomer.

Then, 37 parts by weight of styrene, 13 parts by weight of 2-ethylhexyl acrylate and 0.2 parts by weight of divinylbenzene were newly added to the above monomer oil phase so as to have the composition shown in Table 1, and further azobisdimethyl was added. Valeronitrile 3
Parts by weight and 3 parts by weight of polypropylene wax as an anti-offset agent were added, respectively.

Then, as shown in Table 1, the monomer oil phase obtained as described above was mixed with polyvinyl alcohol (average degree of polymerization: 17
00, saponification degree 80 mol%) in 300 parts by weight of an aqueous solution containing 3 parts by weight, at an oil phase / aqueous phase ratio of 1/3, a homomixer (Co.
Using a Biomixer 610 manufactured by Nippon Seiki Seisakusho, Ltd., the mixture was dispersed with stirring at a rotation speed of 6000 rpm.

After stirring the obtained dispersion liquid at 70 ° C. for 5 hours under low-speed stirring, the mixture is further stirred at 90 ° C. for 1 hour to polymerize the monomer, whereby the polymer constituting the polymer particles can be obtained. A suspension containing substantially spherical polymer particles having a glass transition point of 63 ° C. was obtained.

The particle size distribution of the polymer particles is shown in Table 2.

Next, this suspension was continuously supplied to an Aniura type continuous wet agitation mill (Kobol mill manufactured by Shinko Foudler Co., Ltd.) as shown in FIG. 1, and the temperature, suspension flow rate and The polymer particles were deformed at the peripheral speed of the rotor. Incidentally, zircon having a diameter of 0.75 to 1.0 mm was used as the medium, and the filling rate thereof was 70%.

After that, a mixture of 77% by volume of water containing 23% by volume of methanol and 23% by volume of methanol containing 10 times the equivalent of sodium hydroxide with respect to the amount of vinyl acetate in the polyvinyl alcohol contained in the suspension was added, and the mixture was mixed at a temperature of 50 ° C. The polyvinyl alcohol was saponified by stirring for a time.

Then, the obtained modified spherical polymer particles were separated and washed with water, and then the sodium hydroxide was neutralized with water containing the used sodium hydroxide and an equivalent amount of hydrochloric acid, and the polymer was The particles were washed. Then, the polymer particles were dried under reduced pressure to obtain a toner.

With respect to the toner thus obtained, the flatness, the charge amount (blow-off method) and the amount of the oppositely charged toner are checked, and
The blade cleaning property, the nip width and the toner consumption amount were examined.

The shape, average particle size and flatness of the toner were determined according to the above equation by taking a scanning electron micrograph of the toner particles, randomly selecting 50 particle images. The amount of electrification was measured by the pro-off method after stirring with iron powder carrier at a concentration of 5%.
The amount of reversely charged toner was measured with a charge amount distribution measuring device manufactured by Hosokawa Micron Co., Ltd.

The blade cleaning is performed by an electrostatic copying machine (Toshiba Corp.)
Copying machine REO DRY 4515 type) is used for 10
After copying 000 sheets, the photoreceptor and the image after cleaning the blade were observed and visually evaluated. ○ indicates that the photoconductor has been completely cleaned and the image is clear. △ indicates that the cleaning is partially defective and the image is slightly dirty. × indicates that the entire surface of the photoconductor is defective. Means ,.

The nip width was adjusted by changing the nip width using a fixability evaluation device consisting of a polytetrafluoroethylene heat roll and a silicone rubber back up roll.
It was evaluated with a nick width of 90% or more. Therefore, the smaller the nip width, the better the toner fixability. As for the fixing rate, after a predetermined time has passed after the copy image was formed,
The image was rubbed, and the change in image density at that time was also evaluated.

Toner consumption is the amount of toner required to make 1000 copies after adjusting the surface potential of the photoconductor to an image density of 1.2 using LED printer K-II manufactured by Nippon Kentec Co., Ltd. I also evaluated it.

Example 2 A toner was obtained in the same manner as in Example 1 except that the deforming treatment was performed under the conditions shown in Table 2. The result It is shown in Table 2.

Comparative Examples 1 to 6 As shown in Table 2, toners were obtained with or without saponification treatment and deforming treatment. The results are shown in Table 2.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of essential parts of an example of an Anyurer-type continuous wet stirring mill. 1 ... Stator, 2 ... Rotor, 3 ... Shatter zone, 4 ...
Media, 5 ... Suspension supply port, 6 ... Gear cup / separator, 7 ... Product outlet, 8 ... Hot water.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiro Uchino 3-15, Meiwadori, Hyogo-ku, Kobe, Hyogo Prefecture Bandou Kagaku Co., Ltd. (56) References JP-A-62-266560 (JP, A) Kai 61-279864 (JP, A) JP-A-1-195460 (JP, A) JP-A 63-235955 (JP, A)

Claims (4)

[Claims] 1. A substantially spherical polymer particle obtained by suspension polymerization of a radically polymerizable monomer oil phase in an aqueous phase is modified to have a diameter of 3 to 30 μm and a thickness of 1 to 15 μm. A toner for developing an electrostatic latent image, which has a disk shape having a flatness defined by average thickness / average diameter of 0.5 or less. 2. A substantially spherical polymer particle obtained by suspension polymerization of a radically polymerizable monomer oil phase in an aqueous phase is modified to have a major axis of 3 to 30 μm and a minor axis of 1 to 3. 25 μm, thickness 0.5
~ 15 μm, and 2 × average thickness / (average major axis +
An electrostatic latent image developing toner having an oval shape having a flatness defined by an average short diameter of 0.5 or less. 3. A spherical polymer particle having a particle size of 1 to 30 μm is obtained by suspending a monomer oil phase containing carbon black and charge control agent particles in an aqueous phase and polymerizing the monomer. The suspension containing the spherical polymer particles was treated in an Aniler type continuous wet stirring mill at a temperature within the range of ± 10 ° C. of the glass transition point of the matrix resin of the polymer particles, and the diameter of 3 to 30
μm, a thickness of 1 to 15 μm, and a disk shape having a flatness defined by the average thickness / average diameter of 0.5 or less, or a major axis of 3 to 30 μm, a minor axis of 1 to 25 μm, and a thickness of 0.5 to 1
A toner for developing an electrostatic latent image, which is 5 μm and is deformed into an oval shape having a flatness defined by 2 × average thickness / (average major axis + average minor axis) of 0.5 or less. Manufacturing method. 4. A step of (a) finely and uniformly dispersing both carbon black and charge control agent particles in a radical-polymerizable monomer in the form of fine particles having a particle size of 1 μm or less, and (b) the radical-polymerizable monomer. After adding an azobis-based polymerization initiator to the monomer, it is suspended in an aqueous phase containing polyvinyl alcohol as a suspension stabilizer, and the above monomers are polymerized,
A step of obtaining spherical polymer particles having a particle size of 1 to 30 μm, (c) a suspension containing the polymer particles in an Annular type continuous wet stirring mill in the presence of polyvinyl alcohol, and a matrix resin of the polymer particles. Of glass transition point of
Treated at a temperature in the range of 10 ℃, diameter 3 ~ 30μm, thickness 1
A disk shape having a flatness of 0.5 or less and an average flatness / average diameter of 0.5 or less, or a long diameter of 3 to 30 μm, a short diameter of 1 to 25 μm, and a thickness of 0.5 to 15 μm. And a step of deforming into an oval shape having a flatness defined by 2 × average thickness / (average major axis + average minor axis) of 0.5 or less, (d) then saponifying the polyvinyl alcohol And (e) a step of collecting, washing and drying the polymer particles, a method for producing an electrostatic latent image developing toner.