JPH01244471A - Production of electrostatic latent image developing toner - Google Patents

Abstract

PURPOSE:To obtain a toner superior in stability against environmental conditions and in copying performance by dispersing carbon black and an electrostatic charge controller finely and uniformly into an radically polymerizable monomer, suspending them into an aqueous phase containing polyvinyl alcohol, and saponifying polyvinyl alcohol after polymerization. CONSTITUTION:The toner free from humidity susceptibility and superior in stability against environmental conditions and in copying performance can be obtained by stirring the radically polymerizable monomer and carbon black in the presence of lauryl peroxide, dispersing the carbon black finely and uniformly into the monomer, then dispersing the powdery charge controller finely and uniformly into it, adding azobisdimethylvaleronitrile to it, suspending it in the an aqueous phase containing polyvinyl alcohol, polymerizing the monomer, adding alkali or acid and heating the aqueous phase containing the spherical polymer particles to saponify the polyvinyl alcohol, and separating the polymer particles and drying them.

Description

DETAILED DESCRIPTION OF THE INVENTION 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 is free from fogging. The present invention relates to a method for producing an I-ner for developing electrostatic latent images, which is free of defects and has poor fixing properties.

Kitsunesue p Ushihi has conventionally been used as a developer for electrostatic latent images for electrophotographic copying, i.e.
Toner is generally made by kneading and dispersing a coloring agent such as carbon black into a molten thermoplastic resin, a charge control agent to give the toner the required frictional charging properties, and a wax to give it anti-offset properties. It is manufactured by 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 L-ner thus produced 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 decreased fluidity.

Furthermore, in order for each 1-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 applied to each toner particle. It is important that it is finely dispersed. However, when using the conventional pulverization method described above, 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, and in recent years, a method of directly producing toner by carrying out suspension polymerization or emulsion polymerization of a polymerizable monomer containing a colorant has been developed. Various proposals have been made.

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 veroside is used as a polymerization initiator. That is, in the presence of carbon black, the radically polymerizable carmer usually has a low polymerization rate, and therefore the resulting polymer easily aggregates, making it difficult to use as a toner. On the other hand, when a large amount of polymerization initiator is used to increase the polymerization rate of the -9i polymer, the resulting polymer has a low molecular weight and is inferior in offset resistance as an I-mer.

° Therefore, for example, in Japanese Patent Application Laid-Open No. 53i7735,
After coating carbon black in advance with a silane coupling agent in water and dispersing it in a radically polymerizable monomer in the presence of a peroxide polymerization initiator, the monomer containing this carbon black is coated with an oil. A method has been proposed for producing toner by dispersing the phase in water and subjecting it to suspension polymerization.

According to this method, since the surface of carbon black is coated with a silane coupling agent, inhibition of polymerization 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 also extremely important to finely and uniformly disperse carbon black in the polymerizable jet in order to produce high-performance toner. 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 content of the toner particles differs, 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, Japanese Patent Application Laid-open No. 5,611-6044 discloses, for example, the monomer is heated in the presence of carbon black, graft polymerized to the carbon black, and such graft polymerization is carried out. It is described that carbon black is used. According to this method, carbon black can be given excellent dispersibility in monomers, but graft polymerization of monomers to 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 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 disclosed, for example, in JP-A-57-181553 and JP-A-61-22.
It is described in Publication No. 353. However, this method
Similarly, since the carbon black to be used is limited, I
In addition to being disadvantageous in the industrial production of carbon black, the dispersion of carbon black into the monomer is also not always satisfactory.

As described above, it is not easy to finely and uniformly disperse carbon black in a polymerizable monomer using conventionally known methods, or it is necessary to use very troublesome means for that purpose. .

Regarding charge control agents, for example, JP-A-60-1
Although Japanese Patent No. 92958 proposes a method using a nigrosine dye which has excellent dispersibility in radically polymerizable monomers, it is not generally applicable.

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, because the suspension stabilizer remains on the surface of the L-ner obtained by this method, it is moisture sensitive, that is, highly sensitive 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, Japanese Unexamined Patent Publication No. 53-1
No. 7735 proposes a method of polymerizing a monomer oil phase and then treating the obtained polymer particles 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 the presence of polyvinyl alcohol as a suspension stabilizer. As a result of intensive research to solve the problem that the toner obtained by suspension polymerizing a monomer oil phase below 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 sensitive to moisture 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, which has led to the development of the present invention.

The method for producing a toner for developing an electrostatic latent image according to the present invention is as follows: (a) A radically polymerizable monomer and carbon black are combined in the presence of a polymerization initiator based on a polymerization system. (b) dispersion of the radically polymerizable monomer and powdered charge control agent dissolved in the monomer; (c) After adding an azobis-based polymerization initiator to the radically polymerizable monomer, A step of polymerizing the monomer by suspending it in an aqueous phase containing polyvinyl alcohol as a turbidity stabilizer, (d+) adding an alkali or acid to the aqueous suspension containing the obtained spherical polymer and heating it; , a step of saponifying the polyvinyl alcohol, and (e) a step of separating and drying the obtained spherical polymer.

In the present invention, the radically polymerizable monomer is not particularly limited, and any monomer generally used in the production of toner by conventional polymerization methods can be used. Such monomers include, for example, styrene, 0-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, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methacrylic acid Methyl, 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,
In particular, styrene and a mixture of styrene and acrylic ester or methacrylic ester are preferably used.

Furthermore, in the present invention, the radically polymerizable monomer may contain a small amount of a polyfunctional polymer in order to improve the fixing properties and anti-offset properties of the toner. Examples of such polyfunctional monomers include divinylbenvin, ethylene glycol dimethacrylate, and the like. When such a polyfunctional monomer is used in too large a quantity, the obtained polymer particles become difficult to melt by heating, and 1
- Since the fixability as a toner is poor, it is usually used in an amount of about 1% by weight or less based on the radically polymerizable monomer.

In the present invention, examples of peroxide-based polymerization initiators include henzoyl peroxide 1-, lauryl peroxide, 0-chlorobenzoyl peroxide,
-Methoxyhexyl peroxide and the like are used, and lauryl peroxide is particularly preferably used.

According to the method of the present invention, the radically polymerizable monomer as described above and carbon black are stirred in the presence of the peroxide polymerization initiator, usually for several hours, so that the carbon black has a submicron size or less. It can be uniformly dispersed in the monomer depending on the particle size. This dispersion treatment may be performed at a temperature of 50 to 80°C in order to speed up the dispersion rate of carbon black into the monomer.

In the method of the present invention, carbon black is used in an amount of 2 to 10 parts by weight based on 100 parts by weight of the radical polymerizable polymer. Here, any conventionally known carbon black can be used as the carbon black, but especially when carbon black with a high pH and a small specific surface area is used, a small amount of peroxide-based carbon black is used. Radical polymerization using the azobis-based polymerization initiator described below, which can be finely and uniformly dispersed by a polymerization initiator - carbon black has almost no polymerization inhibiting effect in the stage of suspension polymerization of heavy bodies. do not have.

In the method of the present invention, the peroxide polymerization initiator is usually used in an amount of 1 per 100 parts by weight of carbon black.
It is used in an amount of 0 to 50 parts by weight, preferably 10 to 40 parts by weight. Regarding 100 parts by weight of carbon black,
When the amount of peroxide-based polymerization initiator is less than 10 parts by weight, carbon black cannot be finely and uniformly dispersed in the monomer; on the other hand, when it exceeds 50 parts by weight, the amount of polymerization initiator As a result of the decomposed fragments remaining in the obtained toner, an unpleasant odor is generated when the toner is heated and fixed, 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 i-mer partially polymerizes, the viscosity of the monomer 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 in the presence of a peroxide-based polymerization initiator, carbon black and a polymerization initiator are simultaneously added to the monomer. Carbon black may be dispersed in the monomer using a hole 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. A 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 monomer together with a necessary powdered charge control agent to the radically polymerizable carmer, and the dispersant is added to the monomer. This is usually dissolved in a ball mill for 5 minutes.
By stirring for 0 to 200 hours, the charge control agent 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 carried out at a temperature of 50 to 80"C in order to speed up the dispersion rate of the charge control agent into the monomer.

The 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 surfactants, for example, fatty acid salts, alkyl sulfates, alkyl hanzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinate ester salts, alkyl phosphate ester salts,
Naphthalene sulfonic acid formalin condensate, anionic surfactant such as polyoxyethylene alkyl sulfate, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxy Examples include nonionic surfactants such as ethylene alkylamine, glycerin fatty acid ester, and oxyethylene oxypropylene block polymer, and cationic surfactants such as alkylamine salts and quaternary ammonium salts.

Examples of the silane coupling agent include r-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyl 1-rif 1-gishsilane, vinyltrichlorosilane, T-methacryloxypropyltrimethoxysilane, and T-glycidoxypropyltrimethoxysilane. Silane, T-
Mercaptopropyltrimethoxysilane, γ-aminopropyl 1-ethoxysilane, γ-ureidobropyltrie 1-oxysilane, 3,3,4.4,5,5,6,6
．． 6-nonafluorohexyltrichlorosilane, 3,3
, 4,4,5,5,6.6.6-nonafluorohexylmethyldichlorosilane and the like. Also,
Examples of the reactive silane include methyltrimethoxysilane, phenyltrimethoxysilane, methylphenyldume-1-oxysilane, and diphenyldimethoxysilane.

Examples of the titanium coupling agent include isopropyl triisostearoyl titanate, isopropyl I-lis(dioctylpyrophosphate) titanate, isopropyl tri(N-aminoethylaminoethyl) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, and tetraoctyl bis(ditridecyl phosphite) titanate. -2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate, bis(dioctylpyrophosphate-1.)oxyacetate titanate, bis(dioctylpyrophosphate-1~)ethylenenathanate, isopropyl Trioctanoyl titanate tacryl isostearoyl titanate, isopropyl tridecyl henzenesulfonyl titanate, isoprobyl isostearoyl diacryl titanate 1-, isopropyl 1-li (dioctyl bosphate) titanate,
Examples include isopropyl 1-likumylphenyl titanate-1-, tetraisopropyl bis(dioctylbosphite) titanate-1-, and the like.

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, examples of the polymer or copolymer include styrene-acrylic acid copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-methacrylic acid copolymer, and styrene-methacrylic acid copolymer. Acid-2-hydroxyethyl copolymer, styrene-acrylonitrile copolymer, styrene-glycidyl methacrylate copolymer, methyl methacrylate-acrylic acid copolymer, methyl methacrylate-dimethylaminoethyl methacrylate copolymer, methacryl Methyl methacrylate-2-hydroxyethyl methacrylate copolymer, methyl methacrylate-acrylonitrile copolymer, methacrylic acid-glycidyl methacrylate copolymer, vinyl chloride-vinyl acetate copolymer it coalescence, vinyl chloride-hinyl acetate-vinyl alcohol copolymer, polyvinyl butyral, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butyl acrylate-2-hydroxyethyl methacrylate-1 ~ copolymer, edylene-vinyl acetate copolymer, Vinyl (co)polymers such as polyvinyl acetate, partially sulfonated polystyrene, acrylonitrile
Examples include -fm-based monomers such as butadiene copolymers, cellulose polymers such as diI-cellulose and acetyl cellulose, and crosslinkable resins such as epoxy resins, phenoxy resins, and urethane resins. These polymers may be used alone or as a mixture of two or more.

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 a charge control agent, for example, an ethylene-vinyl acetate copolymer may be used as a dispersant. Combination is preferably used.

In the present invention, the charge control agent may have either positive chargeability or negative chargeability.

Examples of positive charge control agents include electron-donating dyes such as nigrosine dyes represented by the following formulas, alkoxylated amines, alkylamides, quaternary ammonium salts, simple substances and various compounds of phosphorus and tungsten, and molybdenum. Examples include acid chelate pigments, fluorine-based activators, and hydrophobic silica. On the other hand, examples of negative charge control agents include electron-accepting dyes such as metal complex salts of monoazo dyes, electron-accepting organic complexes, chlorinated polyolefins such as chlorinated polyethylene, chlorinated polyesters,
Examples include sulfonylamine of copper phthalocyanine, oil black, naphthenic acid metal salts, fatty acid metal salts such as zinc stearate, resin acid layers, 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 1 based on 100 parts of the radically polymerizable monomer used.
0 parts by weight, preferably in the range of about 0.1 to 5 parts by weight.

When dispersing a charge control agent in a 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. It is preferably used in a range of 10 to 50 parts by weight. When the amount of 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 the amount of dispersant used is too small,
Poor effectiveness in dispersing charge control agents.

In dispersing the charge control agent into the monomer, as in the case of carbon black described above, the charge control agent is preliminarily dispersed in the monomer using a ball mill, etc. The dispersant may be dissolved in 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 not only a two-component type l.toner but also a -component type magnetic toner and a one-component type 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. A magnetic material such as iron is dispersed in a monomer 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 monomer. 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, necessary monomers are additionally added to this dispersion as necessary, and then an azohis-based polymerization initiator is added again as a polymerization initiator. As the azobis-based polymerization initiator, azobisdimethylvaleronitrile, azobisisobutyronitrile, etc. are used, and oil-soluble azobisdimethylhaleronitrile 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 Almost no 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 It is necessary to add a new polymerization initiator, and the newly added polymerization initiator must not be a peroxide polymerization initiator (it must be an azobis-based polymerization initiator. Even if a system polymerization initiator is added, the monomer hardly polymerizes, or even if it polymerizes, the resulting polymer has a low molecular weight.
It is not possible to obtain a toner with good offset resistance.

In the method of the present invention, the amount of the azobis polymerization initiator is 1 to 10 parts by weight per 00 parts by weight of the monomer.
The amount is preferably in the range of 2 to 5 parts by weight. When the amount of the azobis polymerization initiator added is less than 1 part by weight per 100 parts by weight of the monomer, the polymerization rate of the monomer is slow and it is difficult to polymerize at a polymerization rate of 100%. .

On the other hand, the amount of the azobis-based polymerization initiator added was 100% of the monomer.
If the amount is more than 10 parts by weight, the resulting polymer will have a low molecular weight and the toner will have poor anti-offset magnetism, 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 polymerization initiator, and a monomer is mixed with water, and this is stirred at high speed using, for example, a homogenizer to form the oily mixture. An aqueous suspension containing fine droplets of is obtained.

In the present invention, the water mixed with the oily mixture is
Contains polyvinyl alcohol as a suspension stabilizer.

The amount of polyvinyl alcohol in this water is usually 0
．． It is 1 to 5% by weight. Furthermore, in order to prevent polymerization in the aqueous phase, water-soluble inorganic salts such as sodium chloride, sodium sulfate, aluminum sulfate, etc. may be contained.

The aqueous suspension thus obtained is heated at 40-95°C.
Preferably, by stirring at a temperature of about 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 alkali metal hydroxide,
For example, a mixture of water and 1 to 50% by volume, preferably 5 to 30% by volume of a lower aliphatic alcohol, such as methanol, ethanol, propatool, preferably methanol, together with sodium hydroxide or potassium hydroxide. In addition, but not limited to, typically 40 to 70°
Heat at temperature 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, for example, by saponification in the presence of methanol,
There is an advantage that the saponification reaction is carried out rapidly in the form of ester conversion in which vinyl acetate units in polyvinyl alcohol react with methanol to produce methyl acetate.

After saponifying the polyvinyl alcohol present in the suspension in this way, the spherical polymer was separated from the suspension and washed with water or an aqueous solution of the same lower aliphatic alcohol as above, preferably an aqueous methanol solution. Afterwards, 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 further washed with water or an aqueous methanol solution, thus separating and removing polyvinyl alcohol from the spherical polymer. do. Thereafter, the polymer particles are dried and, if necessary, pulverized to obtain a toner.

The alcohol aqueous solution used for washing the polymer particles after saponification of the polyvinyl alcohol is not particularly limited, but is composed of water and its alcohol, preferably methanol, 1 to 50% by volume, preferably 5 to 30% by volume. % is preferred.

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, the washing of the polymer particles after this neutralization is usually carried out with water and 1 to 50% by volume, preferably 5 to 50% by volume.
about 30% by volume of alcohol, preferably methanol,
A mixture with 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, and then neutralized with an alkali. The obtained polymer particles are washed with water.

The l-ner according to the present invention can be obtained as a fine spherical material with a uniform particle size, and has poor fluidity, so it may be possible to put it into practical use as it is. A modifier may also be added to the 1-ner. Such a fluidity improver is usually used in an amount of 0.05 to 1 part by weight, preferably 0.1 to 1 part by weight, per 100 parts by weight of toner.
It is blended in an amount of 0.5 parts by weight.

Further, when the toner according to the present invention is used in a two-component development 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 2 to 2.
20% by weight, preferably in the range 5-10% by weight.

As the carrier, for example, iron powder, Ferrai I powder, powder made of a composite of resin and magnetic material, magnetite powder, etc. are used. Furthermore, a so-called coach 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 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 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 after polymerization of the monomer oil phase and removed from the polymer particles, so that it is highly hydrophobic (and non-moisture sensitive). A toner with significantly improved environmental stability and charging performance can be obtained.

Further, according to the present invention, when carbon black is dispersed 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. 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 fine carbon black and charge control agent are dispersed in this way. The radically polymerizable monomers maintained their dispersion stability even when the oil phase containing them was suspended in an aqueous phase under high-speed shearing, and as a result, the finely dispersed oil phase particles remained stable. each,
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. is polymerized without being substantially affected by the polymerization-inhibiting action of carbon black, thus making it 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 the production of 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, 1 part by weight of lauryl peroxide and carbon black (Diablack #52 (manufactured by Mitsubishi Chemical Corporation, volatile content 1.1%, pl + 7°2, particle size 2)
7 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 the styrene. The resulting mixture was then stirred in an autoclave at 70°C for 1 hour. After this dispersion treatment, no precipitation of carbon black was observed in the monomer.

Next, the mixture thus obtained was added with ethylene-vinyl acetate copolymer (Nippon Synthetic Chemical Industry 01) as a dispersant.
Add 1 part by weight of Soabrene CH) and 2.5 parts by weight of the dye "Spiron Black TRHJ (manufactured by Hodogaya Chemical Industry)" as a negative charge control agent, and mix in a ball mill for 100 hours to control charge. The agent was dispersed in styrene. After this dispersion treatment, the charge control agent has a particle size of about 0.3
μm, and no sedimentation of the charge control agent was observed in the monomer.

After that, 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 obtained mixture so that the monomer composition was as shown in Table 1. Furthermore, an appropriate amount of polypropylene wax was added as an anti-offset agent.

Next, the monomer oil phase thus obtained was placed in an aqueous solution containing polyvinyl alcohol with a concentration of 1% by weight (degree of saponification 88 mol%) and an aqueous sodium chloride solution with a degree of o, IN>a. /Aqueous phase ratio 1.5/5゜0 using Biomigicer (manufactured by Hiki Seiki) at 15,000 rpm.
The mixture was dispersed under stirring at m.m.

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 consisting of 77% by volume of water and 23% by volume of methanol containing an equivalent amount of sodium hydroxide relative to polyvinyl alcohol is added to the aqueous suspension containing the polymer particles,
The polyvinyl alcohol was saponified by stirring at a temperature of 70°C for 3 hours.

Next, the obtained spherical polymer particles were separated and washed with water, and then the sodium hydroxide was neutralized using water containing an equivalent amount of hydrochloric acid to the sodium hydroxide J used.
The polymer particles were 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 ■Characteristics 11
Table 1 shows the copying performance evaluated using 022) at a temperature of 25° C. and a relative humidity of 35%.

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 to saponify polyvinyl alcohol. The properties of the toner similar to Example 1 are shown in Table 1.

Comparative Example 1 A toner was obtained in the same manner as in Example 1, except that polyvinyl alcohol was not saponified.

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 T-chloropropyltrimethoxysilane, 30 parts by volume of ethanol, and 70 parts by volume of ion-exchanged water were added to 30 parts by weight of the polymer particles obtained in Comparative Example 1. After stirring at room temperature for 15 minutes, the polymer particles were centrifuged and dried under reduced pressure at 40° C. for 10 hours. Then,
The polymer particles were washed with ethanol/ion-exchanged water (30/70 volume ratio) to remove unreacted silane coupling agent, and then dried under reduced pressure at 40° C. for 10 hours again.

Table 1 shows the properties of the toner subjected to the silane coupling treatment as described in Example 1.

Claims (4)

[Claims] (1) (a) Stirring the 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) in the presence of a dispersant in which the radically polymerizable monomer and a powdered charge control agent are dissolved in the monomer; Stir and
(c) adding an azobis polymerization initiator to the radically polymerizable monomer and then containing polyvinyl alcohol as a suspension stabilizer; (d) adding an alkali or acid to the aqueous suspension containing the obtained spherical polymer and heating it to saponify the 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) The method for producing a toner for developing electrostatic latent images according to claim 1, wherein the azobis-based polymerization initiator is azobisdimethylvaleronitrile. (4) The method for producing a toner for developing electrostatic latent images according to claim 1, wherein the lower aliphatic alcohol is methanol.