JPH0451822B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing a toner for developing electrostatic latent images, and more specifically, it is non-moisture sensitive, has stable charging characteristics, has excellent durability, and does not cause fogging. The present invention also relates to a method for producing a toner for developing electrostatic latent images having excellent fixing properties. BACKGROUND ART Conventionally, a developer for an electrostatic latent image for electrophotographic copying, that is, a toner, is generally prepared by adding a coloring agent such as carbon black to a molten thermoplastic resin and imparting the required triboelectric charging properties to the toner. charge control agent for
It is manufactured by kneading and dispersing wax etc. for imparting offset resistance, cooling, pulverizing to the required particle size, and classifying. However, when using this method, as mentioned above, the resin mixture containing the colorant etc. needs to be brittle so that it can be easily crushed, but on the other hand, when using a resin that is easily crushed, it is difficult to obtain The collected toner becomes fine powder inside the copying machine, causing contamination inside the machine and fogging of images. On the other hand, when a resin that easily melts is used, filming may occur on the surface of the photoreceptor, or toner particles may fuse together, resulting in a decrease in fluidity. Furthermore, in order for each toner particle to have uniform charging characteristics and to form a high quality copy image, it is necessary that the colorant and charge control agent be uniformly and finely dispersed in each toner particle. is important.
However, when using the above-mentioned conventional pulverization method, the colorant and charge control agent have a wide particle size distribution and are non-uniformly dispersed. As described above, the conventional toner produced by the so-called pulverization method has various drawbacks.
Various methods have been proposed for directly producing toner. However, for example, when carbon black is used as a colorant, as is well known, carbon black has the effect of inhibiting the polymerization of radically polymerizable monomers. In particular, the polymerization inhibiting effect of carbon black is remarkable when peroxide is used as a polymerization initiator. That is, in the presence of carbon black, radically polymerizable monomers usually have a low polymerization rate, and the resulting polymer easily aggregates, making it difficult to use it as a toner. On the other hand, when a large amount of polymerization initiator is used to increase the polymerization rate of monomers, the molecular weight of the resulting polymer is low and the toner has poor offset resistance. Therefore, for example, in Japanese Patent Application Laid-open No. 17735/1983,
After coating carbon black in advance with a silane coupling agent in water and dispersing it in a radical polymerizable monomer in the presence of a peroxide polymerization initiator, the monomer oil containing this carbon black is coated with a silane coupling agent. A method has been proposed for producing toner by dispersing the phase in water and subjecting it to suspension polymerization. According to this method, the surface of carbon black is coated with a silane coupling agent, so that polymerization inhibition by carbon black is avoided. However, since carbon black is inherently hydrophobic, in this method, the treatment of carbon black in an aqueous solution containing a silane coupling agent and the subsequent drying are cumbersome steps. As the number of manufacturing steps increases, manufacturing costs also inevitably increase. On the other hand, in the production of toner by suspension polymerization of polymerizable monomers, it is extremely important to finely and uniformly disperse carbon black in the polymerizable monomers in order to produce high-performance toners. It is.
That is, if the dispersion of carbon black in the monomer is not uniform, when the monomer oil phase containing this carbon black is suspended in the form of fine particles in water, the carbon black will be dispersed between these particles. As a result, the contents of the toner particles differ and the chargeability differs, resulting in, for example, fogging in the copied image or the inability to obtain a copied image with a high color density. In order to disperse carbon black in a polymerizable monomer, for example, JP-A-56-116044 discloses that the monomer is heated in the presence of carbon black, the carbon black is graft-polymerized, and such graft polymerization is carried out. It is described that carbonized carbon black is used. According to this method, carbon black can be given excellent dispersibility in monomers, but graft polymerization of monomers onto carbon black requires a long reaction time at high temperatures. This is disadvantageous in the industrial production of toner. Furthermore, in the subsequent polymerization of the polymerizable monomer, the polymerization inhibiting effect of carbon black cannot be prevented. In particular, this polymerization inhibiting effect is remarkable when a peroxide-based initiator is used as the polymerization initiator. A method of dispersing carbon black having specific physical properties in a monomer in the presence of an azobis-based polymerization initiator is also described in, for example, JP-A-57-181553 and JP-A-61-22353. There is. but,
This method is also disadvantageous in the industrial production of toners since the carbon black that can be used is limited, and the dispersion of carbon black in the monomer is not always satisfactory. As mentioned above, it has been difficult to finely and uniformly disperse carbon black in polymerizable monomers.
According to the known methods, this is not easy or involves very complicated measures. Regarding charge control agents, for example,
60-192958 proposes a method using a nigrosine dye which has particularly excellent dispersibility in radically polymerizable monomers, but this method is lacking in generality. Furthermore, conventionally, in the production of toner by suspension polymerization or emulsion polymerization of polymerizable monomers, a suspension stabilizer such as polyvinyl alcohol is dissolved in water and the monomer oil phase is polymerized in the water. However, the toner obtained by such a method has a residual suspension stabilizer on its surface, so it is moisture sensitive, that is, has high sensitivity to humidity, has poor environmental stability, and has low electrostatic charge. Performance deteriorates, and uncharged toner or reversely charged toner is generated during development of an electrostatic latent image, resulting in fogging of the image or low image density. In order to solve this problem, for example,
No. 53-17735 discloses that after polymerizing the monomer oil phase,
A method has been proposed in which the obtained polymer particles are treated with a reactive silane. However, even with such a method, unreacted silane remains in the toner particles, which inevitably has various harmful effects on the charging performance of the toner. Problems to be Solved by the Invention The present inventors have solved the various problems described above in the production of conventional toners by suspension polymerization of polymerizable monomers, particularly in the presence of polyvinyl alcohol as a suspension stabilizer. As a result of intensive research in order to solve the problem that the toner obtained by suspension polymerization of the monomer oil phase is moisture sensitive, we found that by saponifying polyvinyl alcohol with an alkali after polymerizing the monomer oil phase, The inventors have discovered that it is possible to solve the above problems and to obtain a toner that is not moisture sensitive and has excellent environmental stability, leading to the present invention. Furthermore, the present inventors have discovered a method of finely and uniformly dispersing carbon black and a charge control agent in a monomer, and in addition to the above, the carbon black and charge control agent are uniformly and finely dispersed. In addition, the inventors have discovered that it is possible to obtain a toner that is made of high molecular weight polymer particles having a uniform particle size and has excellent copying performance, leading to the present invention. Means for Solving the Problems The method for producing a toner for developing electrostatic latent images according to the present invention includes: (a) stirring a radically polymerizable monomer and carbon black in the presence of a peroxide polymerization initiator; a step of finely and uniformly dispersing carbon black in the monomer; (b) dissolving the radically polymerizable monomer in which the carbon black is dispersed and a powdered charge control agent in the monomer; a step of finely and uniformly dispersing the charge control agent in the monomer by stirring in the presence of a dispersant; (c) a radically polymerizable monomer in which the carbon black and the charge control agent are dispersed; a step of adding an azobis-based polymerization initiator to and then suspending the monomer in an aqueous phase containing polyvinyl alcohol as a suspension stabilizer to polymerize the monomer; (d) an aqueous solution containing the obtained spherical polymer; It is characterized by comprising the steps of adding an alkali or acid to the suspension and heating it to saponify the polyvinyl alcohol, and (e) separating and drying the obtained spherical polymer. In the present invention, the radically polymerizable monomer is not particularly limited, and any monomer that is generally used in the production of toner by conventional polymerization methods can be used. Examples of such monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-chlorostyrene, vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, and acrylic acid. Propyl, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methacryl Methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate,
n-octyl methacrylate, 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-vinylpyridine, 4-vinylpyridine, and the like. However, in the present invention, among these monomers, styrene and mixtures of styrene and acrylic esters and methacrylic esters are particularly preferably used. Further, in the present invention, the radically polymerizable monomer may contain a small amount of a polyfunctional monomer in order to improve the fixing properties and offset resistance of the toner. Examples of such polyfunctional monomers include divinylbenzene and ethylene glycol dimethacrylate. When such polyfunctional monomers are used in too large a quantity, the resulting polymer particles become difficult to heat and melt, resulting in poor fixing properties as a toner. It is used in a range of about 1% by weight or less. In the present invention, examples of peroxide-based polymerization initiators include benzoyl peroxide,
Lauryl peroxide, o-chlorobenzoyl peroxide, o-methoxybenzoyl peroxide, etc. are used, and lauryl peroxide is particularly preferably used. According to the method of the present invention, the radically polymerizable monomer described above and carbon black are stirred in the presence of the peroxide polymerization initiator, usually for several hours, thereby substituting carbon black. It can be uniformly dispersed in the monomer with a particle size of less than a micron. This dispersion treatment may be carried out at a temperature of 50 to 80°C in order to speed up the dispersion of carbon black into the monomer. In the method of the present invention, carbon black is added to 100 parts by weight of the radical polymerizable monomer.
It is used in a range of 2 to 100 parts by weight. Here, the carbon black can be any conventionally known carbon black, but
In particular, when carbon black with a high pH and a small specific surface area is used, it is not only possible to disperse it finely and uniformly with a small amount of peroxide-based polymerization initiator, but also to disperse it finely and uniformly using a small amount of peroxide-based polymerization initiator. In the stage of suspension polymerization of radically polymerizable monomers using a polymerization initiator, carbon black has almost no polymerization inhibiting effect. In the method of the present invention, the peroxide polymerization initiator is generally used in an amount of 10 to 50 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of carbon black. Per 100 parts by weight of carbon black, 10 parts of peroxide polymerization initiator
If it is less than 50 parts by weight, carbon black cannot be finely and uniformly dispersed in the monomer, while if it exceeds 50 parts by weight, decomposed fragments of the polymerization initiator may be obtained in the toner. Residual results;
When the toner is heated and fixed, it generates a strange odor, which is not desirable in practical terms. When dispersing carbon black in monomers, when using an azobis-based polymerization initiator such as azobisbutyronitrile or azobisdimethylvaleronitrile instead of a peroxide-based polymerization initiator, carbon The black cannot be finely and uniformly dispersed in the monomer, and the carbon black is dispersed in the monomer while still coagulating with each other and forming mostly large particles. Furthermore, since the monomers are partially polymerized, the viscosity of the monomers containing carbon black increases. This increase in the viscosity of the monomer has a detrimental effect on the formation of minute oil droplets of the monomer in water. In the method of the present invention, when carbon black is dispersed in a radically polymerizable monomer while a peroxide-based polymerization initiator is dispersed, carbon black and a polymerization initiator are simultaneously added to the monomer. Carbon black may be dispersed in the monomer using a ball mill or the like, but it is also possible to preliminarily disperse carbon black in the monomer using a ball mill or the like and then add peroxide to this. The system polymerization initiator may be dissolved and stirred. Next, according to the method of the present invention, a dispersant soluble in the monomer is added to the radically polymerizable monomer in which the carbon black is dispersed, together with a necessary powdered charge control agent. By dissolving the dispersant in the monomer and stirring this, for example, in a ball mill, usually for 50 to 200 hours,
The charge control agent has a thickness of about 0.5 μm or less, preferably about 0.3 μm.
It can be uniformly dispersed in the monomer with a particle size of about m. This dispersion treatment is also carried out at 50 to 80°C in order to speed up the dispersion rate of the charge control agent into the monomer.
It may be carried out at a temperature of The above-mentioned dispersant that can be used in the present invention may be a low molecular weight substance or a high molecular weight substance. Examples of the low molecular weight dispersant include surfactants, silane coupling agents, titanium coupling agents, and oligomers having isocyanate groups and epoxy groups. More specifically, as a surfactant, for example,
Fatty acid salts, alkyl sulfates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, dialkyl sulfosuccinates,
Anionic surfactants such as alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, polyoxyethylene fatty acid esters, polyoxyethylene Nonionic surfactants such as sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethylene oxypropylene block polymer, alkylamine salts,
Cationic surfactants such as quaternary ammonium salts can be mentioned. Examples of the silane coupling agent include γ-
Chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-amino Propyltriethoxysilane, γ-ureidopropyltriethoxysilane, 3,3,4,4,5,5,6,6,
6-nonafluorohexyltrichlorosilane,
Examples include 3,3,4,4,5,5,6,6,6-nonafluorohexylmethyldichlorosilane. Examples of the reactive silane include methyltrimethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane, and diphenyldimethoxysilane. Examples of titanium coupling agents include isopropyl triisostearoyl titanate, isopropyl tris(dioctylpyrophosphate) titanate, isopropyl tri(N-aminoethylaminoethyl) titanate, tetraoctyl bis(ditridecylphosphite) titanate, and tetra- 2,2-diallyloxymethyl-1
-butyl)bis(ditridecyl)phosphite titanate, bis(dioctylpyrophosphate)oxyacetate titanate, bis(dioctylpyrophosphate)ethylene titanate,
Isopropyltrioctanoyltitanate, Isopropyldimethacrylisostearoyltitanate, Isopropyltridecylbenzenesulfonyltitanate, Isopropylisostearoyldiacryltitanate, Isopropyltri(dioctylphosphate)titanate, Isopropyltricumylphenyltitanate, Tetraisopropylbis(dioctylphosphite) Titanates and the like can be mentioned. Further, as the high molecular weight dispersant, various polymers and copolymers having functional groups are preferable, such as carboxyl group, sulfone group, hydroxyl group, halogen group, epoxy group, cyano group, nitrile group, butyral group, Examples include polymers and copolymers having ester groups, carbonyl groups, amino groups, etc. as functional groups. More specifically, the above polymer or copolymer includes, for example, styrene-acrylic acid copolymer,
Styrene-dimethylaminoethyl methacrylate copolymer, styrene-methacrylic acid copolymer, styrene-2-hydroxyethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-glycidine methacrylate copolymer, methacrylic acid Methyl-acrylic acid copolymer, methyl methacrylate-dimethylaminoethyl methacrylate copolymer, methyl methacrylate-methacrylic 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-
Vinyl (co)polymers such as hydroxyethyl methacrylate copolymer, ethylene-vinyl acetate copolymer, polyvinyl acetate, partially sulfonated polystyrene, rubber-based polymers such as acrylonitrile-butadiene copolymer, nitrocellulose, acetyl Examples include cellulose polymers such as cellulose, crosslinkable resins such as epoxy resins, phenoxy resins, and urethane resins. These polymers alone,
Or it is used as a mixture of two or more types. In particular, in the present invention, a dispersant having a functional group that has a strong interaction with the charge control agent used is preferably used. For example, when an electron-accepting dye such as a metal complex 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,
Ethylene-vinyl acetate copolymer is preferably used. In the present invention, the charge control agent has positive chargeability,
It may have either negative chargeability or chargeability. As the positive chargeability control agent, for example, the following formula Electron-donating dyes such as nigrosine dyes shown in the following, alkoxylated amines, alkylamides, quaternary ammonium salts, simple substances and various compounds of phosphorus and tungsten, molybdate chelate pigments,
Examples include fluorine-based activators and hydrophobic silica. On the other hand, examples of negative chargeability control agents include: electron-accepting dyes such as metal complexes of monoazo dyes shown in Examples include salts, fatty acid metal salts such as zinc stearate, fatty acid soaps, and the like. However, the above charge control agent is merely an example, and the present invention is not limited in any way to the charge control agent used. Such a charge control agent is usually used in an amount of about 0.1 to 10 parts by weight, preferably about 0.1 parts by weight, based on 100 parts by weight of the radically polymerizable monomer used.
It is used in a range of 5 parts by weight. When dispersing the charge control agent in the radically polymerizable monomer, the above-mentioned dispersant is usually used in an amount of 1 to 100 parts by weight per 100 parts by weight of the charge control agent, although it varies depending on the particle size of the charge control agent used. Preferably
It is used in a range of 10 to 50 parts by weight. When the amount of the dispersant used is too large, the viscosity of the mixture during dispersion operation becomes high, making it difficult to make the charge control agent fine.On the other hand, when it is too small, the dispersion of the charge control agent is insufficiently effective. In dispersing this charge control agent into the monomer, as in the case of carbon black mentioned above,
The charge control agent may be preliminarily dispersed in the monomer using a ball mill or the like, and then the dispersant may be dissolved therein and stirred. Of course, the dispersant and the charge control agent may be added to the monomer at the same time and mixed by stirring using a ball mill or the like. Further, the toner according to the present invention may be a two-component toner, a one-component magnetic toner, or a one-component non-magnetic toner. In the production of magnetic toner, magnetic materials include, for example, ferrite such as triiron tetroxide, magnetic oxides such as magnetite, or various magnetic metals. 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 magnetic materials are dispersed in monomers in advance using an appropriate mixing and dispersing means such as a ball mill, and then, according to the present invention, carbon black and a charge control agent are dispersed in the monomers. It is preferable to let According to the method of the present invention, as described above, magnetic materials and other additives are dispersed in the monomer, and then carbon black and a charge control agent are dispersed in the monomer. After that, add to this dispersion,
If necessary, after additionally adding required monomers, an azobis-based polymerization initiator is added again as a polymerization initiator. As the azobis-based polymerization initiator, azobisdimethylvaleronitrile, azobisisobutylnitrile, etc. are used, and oil-soluble azobisdimethylvaleronitrile is particularly preferably used. Here, without newly adding an azobis-based polymerization initiator, an oil dispersion consisting of carbon black and a monomer is dispersed as minute oil droplets in water using a homogenizer, etc., and even when heated, the monomer content remains. Almost no body polymerization occurs. That is, most of the peroxide-based polymerization initiator added to the monomer when dispersing carbon black into the monomer is decomposed during the dispersion process of carbon black, so in the present invention, it is added at the stage of polymerization. It is necessary to add a new polymerization initiator, and the newly added polymerization initiator must be an azobis-based polymerization initiator rather than a peroxide polymerization initiator. Even if a new peroxide polymerization initiator is added at the polymerization stage, the monomer hardly polymerizes, or even if it polymerizes, the resulting polymer has a low molecular weight, resulting in a toner with excellent offset resistance. I can't. In the method of the present invention, the amount of the azobis polymerization initiator is 1 to 1 to 100 parts by weight of the monomer.
10 parts by weight, preferably in the range of 2 to 5 parts by weight. The amount of azobis polymerization initiator added is
When it is less than 1 part by weight per 100 parts by weight,
The polymerization rate of the monomer is slow, making it difficult to polymerize at a polymerization rate of 100%. On the other hand, the amount of azobis polymerization initiator added is 10 parts by weight per 100 parts by weight of monomer.
If the amount is more than 1 part by weight, the resulting polymer will have a low molecular weight and the toner will have poor offset resistance, which is not preferable. Next, according to the method of the present invention, an oily mixture containing carbon black, a charge control agent, an azobis-based polymerization initiator, and a monomer is mixed with water, and this is stirred at high speed using, for example, a homogenizer. An aqueous suspension containing fine droplets of an oily mixture is obtained. In the present invention, the water mixed with the oily mixture contains polyvinyl alcohol as a suspension stabilizer. The amount of polyvinyl alcohol in this water is usually 0.1 to 5% by weight. Furthermore,
To prevent polymerization in the aqueous phase, water-soluble inorganic salts, such as sodium chloride, sodium sulfate,
It may also contain aluminum sulfate or the like. The aqueous suspension thus obtained is 40 to 95
By stirring at a temperature of approximately 50 to 90°C, the radically polymerizable monomer is polymerized to produce a spherical polymer. In the method of the present invention, after such suspension polymerization, the polyvinyl alcohol as the suspension stabilizer is saponified using an alkali or acid. In the case of alkali saponification, about 1000 times the equivalent of the polyvinyl alcohol used, preferably 5 to 50 times the equivalent of an alkali metal hydroxide, such as sodium hydroxide or potassium hydroxide, together with water and one of them.
~50% by volume, preferably 5-30% by volume, of a mixture with a lower aliphatic alcohol, such as methanol, ethanol, propanol, preferably methanol, is added, typically, but not limited to,
Heat at a temperature of 40 to 70°C for about 1 to 10 hours. In the alkaline saponification of polyvinyl alcohol in a suspension, using a lower aliphatic alcohol such as methanol increases the water wettability of the surface of the spherical polymer particles produced in suspension polymerization, making the saponification quick and smooth. There are advantages to doing so. Furthermore, saponification in the presence of methanol, for example, has the advantage that the vinyl acetate unit in polyvinyl alcohol reacts with methanol and the saponification reaction is quickly carried out in the form of ester conversion to produce methyl acetate. After saponifying the polyvinyl alcohol present in the suspension in this way, the spherical polymer is separated from the suspension and washed with water or the same aqueous lower aliphatic alcohol solution as above, preferably an aqueous methanol solution. The alkali metal hydroxide used is neutralized by washing with an aqueous solution containing an acid such as hydrochloric acid or an aqueous methanol solution, and the polyvinyl alcohol is separated and removed from the spherical polymer by further washing with water or an aqueous methanol solution. . Thereafter, the polymer particles are dried and, if necessary, pulverized to obtain a toner. In particular, the alcohol aqueous solution used for washing the polymer particles after saponification of the polyvinyl alcohol is
Preferred, but not limited, is a mixture of water and its alcohol, preferably methanol, from 1 to 50% by volume, preferably from 5 to 30% by volume. Furthermore, it is sufficient to use the acid for neutralizing the alkali metal hydroxide in an equivalent amount to the alkali metal hydroxide used, and the same alcoholic aqueous solution as described above containing such an acid is preferably used. Furthermore, for washing the polymer particles after this neutralization, a mixture of water and alcohol, preferably methanol, in an amount of about 1 to 50% by volume, preferably about 5 to 30% by volume, 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 alcohol, preferably methanol, is added and heated.
Thereafter, the resulting polymer particles are neutralized with alkali and washed with water. The toner according to the present invention can be obtained as fine spherical particles with uniform particle size and has excellent fluidity, so it can be put to practical use as is. may be further blended into the toner. Such flow improvers are usually used in amounts of 0.05 parts by weight per 100 parts by weight of toner.
-1 part by weight, preferably 0.1 to 0.5 part by weight. Further, when the toner according to the present invention is used in a two-component developing system, a substance called a carrier, which is well known in the electrostatic electrophotographic technical field, is added to the toner 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 made of a composite of resin and magnetic material, magnetite powder, etc. are used. Furthermore, a so-called coating carrier can also be used.
However, it is not limited to these. Effects of the Invention As described above, according to the present invention, carbon black is finely and uniformly dispersed in a radically polymerizable monomer in the presence of a peroxide-based polymerization initiator, and further, in the presence of a dispersant. The charge control agent is finely and uniformly dispersed in the step below, and then an azobis-based polymerization initiator is newly added to the radically polymerizable monomer in which the carbon black and the charge control agent have been dispersed. The obtained oil phase containing the monomer is suspended in water in the presence of polyvinyl alcohol to undergo suspension polymerization, and then the polyvinyl alcohol is saponified and removed to obtain a toner. Therefore, according to the present invention, polyvinyl alcohol as a suspension stabilizer is saponified and removed from the polymer particles after polymerization of the monomer oil phase, so that it is highly hydrophobic, non-moisture sensitive, and thus A toner with significantly improved environmental stability and charging performance can be obtained. Further, according to the present invention, when dispersing carbon black in a monomer, it is possible to stably disperse the carbon black to a state where it does not settle in the monomer, that is, to a state where it undergoes micro-Brownian motion, and further, After this, the radically polymerizable monomer can be made fine until the charge control agent has a particle size of about 0.5 μm or less, so the radical in which the fine carbon black and the charge control agent are dispersed is used. Even when the oil phase containing the polymerizable monomer is suspended in an aqueous phase under high-speed shearing, its dispersion stability is maintained, and as a result, each of the finely dispersed oil phase particles has Carbon black and a charge control agent are uniformly and finely dispersed and included. Moreover, according to the present invention, the polymerizable monomer in which the carbon black and the charge control agent are finely and uniformly dispersed is subjected to suspension polymerization using an azobis-based polymerization initiator. Since the monomer is polymerized without being substantially affected by the polymerization inhibiting effect of carbon black, it is thus possible to obtain high molecular weight polymer particles at a high polymerization rate. EXAMPLES The present invention will be explained below with reference to examples of manufacturing a two-component non-magnetic toner, but the present invention is not limited to these examples in any way. Example 1 50 parts by weight of styrene and 1 part lauryl peroxide
Weight part and carbon black (“dia black”)
#52 (manufactured by Mitsubishi Chemical Industries, Ltd., volatile content 1.1%, PH7.2,
5 parts by weight (particle size 27 mμ) and 2 parts by weight of lauryl peroxide were added and mixed in a ball mill for 30 minutes to disperse carbon black in styrene. The resulting mixture was then stirred in an autoclave at 70°C for 1 hour. After this distributed processing,
No precipitation of carbon black was observed in the monomer. Next, 1 part by weight of an ethylene-vinyl acetate copolymer (Soabrene CH manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.) as a dispersant and a dye "Spirone Black" as a negative charge control agent were added to the mixture thus obtained.
Add 2.5 parts by weight of "TRH" (manufactured by Hodogaya Chemical Industry Co., Ltd.),
The mixture was mixed in a ball mill for 100 hours to disperse the charge control agent in the styrene. After this dispersion treatment, the particle size of the charge control agent was approximately 0.3 μm, and no sedimentation of the charge control agent was observed in the monomer. Thereafter, 40 parts by weight of styrene, 10 parts by weight of 2-ethylhexyl acrylate, and 0.3 parts by weight of divinylbenzene were newly added to the resulting mixture so that the monomer composition was as shown in Table 1, and further, offset prevention was added. An appropriate amount of polypropylene wax as an agent was added to each. Next, the monomer oil phase thus obtained was mixed with polyvinyl alcohol (saponification degree: 1% by weight).
88 mol%) and an aqueous sodium chloride solution with a concentration of 0.1N, stirred at a rotation speed of 15,000 rpm using a biomixer (manufactured by Nippon Seiki Co., Ltd.) at an oil phase/water phase ratio of 1.5/5.0. distributed below. The obtained dispersion was stirred at 70° C. for 5 hours under high speed stirring, and then further stirred at 90° C. for 1 hour to polymerize the monomers. Next, a mixture of 77% by volume of water containing an equivalent amount of sodium hydroxide to polyvinyl alcohol and 23% by volume of methanol was added to the aqueous suspension containing the polymer particles, and the mixture was stirred at a temperature of 70°C for 3 hours. ,
Saponified polyvinyl alcohol. Next, the obtained spherical polymer particles were separated and washed with water, and then the sodium hydroxide was neutralized using water containing hydrochloric acid in an equivalent amount to the sodium hydroxide used, and the polymer particles were washed with water. Washed. Thereafter, the obtained polymer particles were dried under reduced pressure to obtain a toner according to the present invention. The obtained polymer particles were centrifuged, washed repeatedly with water, and then dried under reduced pressure to obtain a toner according to the present invention. Regarding this toner, its surface hydrophobicity, charge amount (blow-off method), reverse charge amount, and electrostatic copying machine (SANYO Electric Co., Ltd. 1102Z) were used at a temperature of 25℃ and relative humidity.
Table 1 shows the copying performance evaluated under the 35% condition. Example 2 A toner was obtained in the same manner as in Example 1, except that sodium hydroxide in an amount of 50 equivalents of polyvinyl alcohol was used for saponification of polyvinyl alcohol. The properties of the toner similar to Example 1 are shown in Table 1.

【table】

[Table] Highly hydrophobic surface.
Comparative Example 1 In the same manner as in Example 1, except that polyvinyl alcohol was not saponified,
Got toner. The properties of the toner similar to Example 1 are shown in Table 1. Comparative Example 2 The polymer particles obtained in Comparative Example 1 were washed with water, and 1.0 parts by weight of γ-chloropropyltrimethoxysilane, 30 parts by volume of ethanol, and 70 parts by volume of ion-exchanged water were added to 30 parts by weight, and the mixture was heated to room temperature. After stirring for 15 minutes, the polymer particles were centrifuged and dried under reduced pressure at 40°C for 10 hours. Next, the polymer particles were washed with ethanol/ion-exchanged water (30/70 volume ratio) to remove unreacted silane coupling agent, and then washed again with 40
It was dried under reduced pressure at ℃ for 10 hours. Table 1 shows the properties of the toner subjected to the silane coupling treatment as described in Example 1.

Claims (1)

[Claims] 1 (a) A radically polymerizable monomer and carbon black are stirred in the presence of a peroxide polymerization initiator to finely and uniformly disperse carbon black in the monomer. (b) stirring the radically polymerizable monomer in which the carbon black is dispersed and a powdered charge control agent in the presence of a dispersing agent dissolved in the monomer; (c) Adding an azobis-based polymerization initiator to the radical polymerizable monomer in which the carbon black and charge control agent are dispersed, and then adding a suspension stabilizer to the radical polymerizable monomer in which the carbon black and charge control agent are dispersed. (d) Adding an alkali or acid to the aqueous suspension containing the obtained spherical polymer and heating it to polymerize the above monomer by suspending it in an aqueous phase containing polyvinyl alcohol. A method for producing a toner for developing an electrostatic latent image, comprising the steps of: saponifying polyvinyl alcohol; and (e) separating and drying the obtained spherical polymer. 2. The method for producing a toner for developing electrostatic latent images according to claim 1, wherein the peroxide polymerization initiator is lauryl peroxide. 3. Claim 1, wherein the azobis-based polymerization initiator is azobisdimethylvaleronitrile.
A method for producing a toner for developing an electrostatic latent image as described in . 4. The method for producing a toner for developing electrostatic latent images according to claim 1, wherein the lower aliphatic alcohol is methanol.