JPH0646306B2 - Method for manufacturing toner for electrophotography - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a toner for electrophotography using a polymerization method.

(Prior Art) In electrophotography, after uniformly charging the photoreceptor,
An optical image based on the original image is exposed to the photoconductor to eliminate or reduce charges in the light-irradiated portion to form an electrostatic latent image based on the original image on the photoconductor, and after that, development containing toner is performed. It is visualized by the agent. This visualized toner image is generally transferred to an appropriate transfer member and fixed to form a so-called copy.

The developer used in the above process is basically composed mainly of a colorant for developing the electrostatic latent image and a binder for fixing the image on the transfer body. Are roughly classified into so-called wet (liquid) developers and dry developers.

The dry developer can be further divided into a two-component developer and a one-component developer, the former consisting of a carrier and a toner, and the latter consisting of only a toner. In other words, it is a two-component type developer that obtains toner having a polarity opposite to that of the electrostatic charge image necessary for developing the electrostatic charge image on the photoconductor by frictional charging of the carrier and the toner. A one-component developer is one that is charged by friction between other members or friction with other members in the developing device.

Conventionally, such a toner for a dry developer is generally prepared by melting and kneading a coloring material such as carbon black and / or magnetic powder such as magnetite into a thermoplastic resin to form a dispersion, and then appropriately pulverizing it. It has been manufactured by a method in which an impact force is mechanically applied by an apparatus to pulverize the dispersion into a desired particle size and, if necessary, further classify it into a toner (hereinafter, this method is referred to as a pulverization method. ).

Further, Japanese Patent Publication No. 43-10799 proposes a method for producing completely spherical toner particles by spray-drying an emulsion obtained by an emulsion polymerization method.

Further, as a method for producing a toner using a polymerization method to solve the drawbacks of the pulverization method, a method for producing a toner by a suspension polymerization method is proposed in Japanese Patent Publication No. 51-14895 and Japanese Patent Publication No. 57-53756. Has been done. When the suspension polymerization method is used, a spherical toner is obtained.

(Problems to be Solved by the Invention) However, the pulverization method not only requires a large amount of energy for melt-kneading and pulverizing, but also the manufactured toner inevitably has many drawbacks. . In particular, when a desirable resin is used in the melt-kneading process and the crushing process, for example, when a resin that easily melts is used, agglomeration (caking) during toner storage and fog due to toner filming on the photoconductor are caused. If a resin that is easily crushed is used, the toner is crushed into fine toner in the developing machine, causing image fog and stains inside the machine.

In addition, the colorant dispersed in the resin appears on the surface of the pulverized toner, which causes a decrease in the triboelectric charge amount in a high humidity state and a drop in the colorant in the developing machine.
This causes undesired development such as carrier surface contamination or photoreceptor surface contamination.

On the other hand, the toner obtained by using emulsion polymerization-spray drying and suspension polymerization has solved some of the drawbacks of the toner obtained by the pulverization method, but it has been found that it causes new defects. Was issued. That is, the emulsifying agent or the suspending agent remains in the toner particles, so that the charging stability and the blocking property are deteriorated, and the toner particles obtained are spherical, so that the cleaning property is poor.

On the other hand, in the case of producing a toner by emulsion polymerization, it is possible to salt out the emulsion polymerization liquid and collect the particles, and pulverize the particles to an appropriate particle size. There is a drawback that the moisture resistance is significantly reduced.

Thus, until now, no sufficiently satisfactory toner has been obtained by the polymerization method.

The present invention solves the above problems in the conventional toner manufacturing method, and is excellent in image density, resolution, and gradation, and particularly excellent in durability and moisture resistance, and is easy to clean and charge stable. The present invention provides a method for producing an electrophotographic toner capable of improving the blocking property, which is suitable for dry development, by using a polymerization method.

(Means for Solving Problems) The present invention provides a polymerizable monomer, a colorant, and / or a magnetic powder, an oil-soluble polymerization initiator, or an oil-soluble polymerization initiator and a water-soluble compound having less than the same weight. The polymerization initiator of is emulsified and dispersed in the presence of an emulsifier and polymerized to produce a main resin component, and a coagulant is added to the obtained polymerization liquid to a temperature not lower than the glass transition point of the main resin component and not higher than 150 ° C. Solidify while heating, or solidify by adding a toughening agent to the resulting polymerization liquid, and then solidify the resulting particles to 150 ° C or above the glass transition point of the main resin component.
The present invention relates to a method for producing an electrophotographic toner, which comprises heating.

Polymerization of the polymerizable monomer in the present invention is carried out by emulsifying and polymerizing the polymerizable monomer in an aqueous medium containing an emulsifier.

During this emulsification and dispersion, a colorant and / or magnetic powder, an oil-soluble polymerization initiator or an oil-soluble polymerization initiator and a water-soluble polymerization initiator less than this weight are present. In addition, an offset preventing agent, a charge control agent, a fluidity improving agent, a toner property improving agent such as a cleaning property improving agent, a stabilizer for assisting emulsion dispersion, and a chain transfer agent can be appropriately present.

As a method of emulsifying and dispersing the polymerizable monomer in the aqueous medium, the polymerizable monomer, the emulsifier and the aqueous medium may be simultaneously stirred and mixed, and the polymerizable monomer is added to the aqueous medium in which the emulsifier is dissolved. However, the mixture may be mixed with stirring.

An oil-soluble polymerization initiator is used as the polymerization initiator,
Further, an oil-soluble polymerization initiator and a water-soluble polymerization initiator less than the same weight as that are used. As a polymerization initiator,
When the amount of the water-soluble polymerization initiator is large, the obtained toner tends to be hygroscopic, so that the toner is liable to be reduced in triboelectric charge amount and image fog in a high humidity atmosphere.

The polymerization initiator may be added after the emulsification and dispersion, but before the emulsification and dispersion, the oil-soluble polymerization initiator is a polymerizable monomer, and when the water-soluble polymerization initiator is used, it is an aqueous medium. It is preferable to dissolve in advance.

Further, in order to improve the dispersion in the resin, the colorant and / or the magnetic powder is preferably used by dissolving or dispersing the polymerizable monomer in advance, rather than adding it after the above dispersion. The same applies to the toner property improver used as necessary. Further, the stabilizer may be used if necessary, but it may be added after the dispersion or dissolved in an aqueous medium in advance.

The stirring and mixing in the above dispersion may be performed at a relatively high speed by using an ordinary stirrer, but an emulsifier such as a high speed shearing disperser, a homogenizer, a colloid mill, a flow mixer, an ultrasonic emulsifier, a static mixer, etc. Preference is given to using the device. This is also the case when the colorant and / or the magnetic powder and the toner property improving agent used as necessary are dispersed in the polymerizable monomer.

Polymerization may be carried out after the emulsification and dispersion, or while emulsification and dispersion is performed,
It is preferable to carry out at a temperature of ~ 120 ° C, especially 50 ~
It is preferably carried out at a temperature of 90 ° C.

This polymerization is preferably carried out until the polymerization rate becomes 99% by weight or more, and particularly preferably 99.9% by weight or more. If the polymerization rate is low and the amount of residual monomer is high, the toner properties, especially the storage stability, tend to be poor.

The polymer obtained by polymerization preferably has a weight average molecular weight of 50,000 or more. If the molecular weight is too small, the cleaning property and anti-blocking property tend to deteriorate.

The obtained polymer has a glass transition point of 30 to 90 ° C.
Is preferable, and particularly 50 to 80 ° C is preferable. If the glass transition point is too low, the blocking resistance tends to decrease, and if it is too high, the fixability tends to decrease. The glass transition point can be adjusted mainly by selecting the polymerizable monomer used.

By such polymerization, particles of about 3 μm or less are obtained.

Next, the materials used for the polymerization will be described.

Examples of the polymerizable monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-
Ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn octyl styrene, pn-nonyl styrene, pn-decyl styrene , Pn-dodecylstyrene, n-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and other styrenes and their derivatives, ethylene, propylene,
Ethylene unsaturated monoolefins such as butylene and isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide,
Vinyl halides such as vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl esters such as vinyl butyrate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate,
Propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-chloromethyl acrylate, methyl methacrylate, ethyl methacrylate, methacryl Propyl acid, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, acrylic Α-methylene aliphatic monocarboxylic acid esters such as diethylaminoethyl acid ester and diethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile,
Acrylic acid or methacrylic acid derivatives such as acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and in some cases acrylic acid, methacrylic acid, maleic acid , Fumaric acid, etc. can also be used. Further, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone, N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole and N. -N-vinyl compounds such as vinylpyrrolidone and vinylnaphthalene salts may be used alone or in combination of two or more. Of these polymerizable monomers, 40 or more styrene or styrene derivative is used.
The amount of -100% by weight is very excellent in fixing property when the toner is copied on the paper by the electrophotographic copying machine.

Further, as the polymerizable monomer of the present invention, a compound having two or more polymerizable double bonds, which serves as a crosslinking agent, can be partially used. Aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and their derivatives, diethylene carboxylic acid esters such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, N, N divinyl All divinyl compounds such as aniline, divinyl ether, divinyl sulphite and compounds having 3 or more vinyl groups can be used alone or as a mixture. The amount of the crosslinking agent used is preferably 0 to 20% by weight, more preferably 0 to 5% by weight, based on the total amount of the polymerizable monomers.

The aqueous medium used for the emulsification dispersion is mainly water, but depending on the case, a water-soluble organic solvent such as methanol, ethanol, or methyl cellosolve may be mixed with water.
The water-soluble organic solvent is preferably 10% by weight or less with respect to water.
The ratio of the polymerizable monomer to the aqueous medium is preferably 40/60 to 90/10 in weight ratio of the former / the latter. If this proportion is too small, it becomes difficult to emulsify and disperse, and if it is too large, the yield decreases.

As the emulsifier, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant and a nonionic surfactant may be used. Of these, it is preferable to use an anionic surfactant when producing a negatively chargeable toner and to use a cationic surfactant when producing a positively chargeable toner. In these cases, in order to improve the dispersion stability, it is preferable to use a nonionic surfactant together.

Examples of the anionic surfactant include fatty acid salts such as sodium oleate and potassium castor oil, alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, and alkylnaphthalenesulfonates. , Dialkyl sulfosuccinate, alkyl phosphate ester salt, naphthalene sulfonic acid formalin condensate,
There are polyoxyethylene alkyl sulfate ester salts and the like.

Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin, fatty acid ester, oxyethylene. -Oxypropylene block polymer and the like.

Examples of the cationic surfactant include alkylamine salts such as laurylamine acetate and stearylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride and stearyltrimethylammonium chloride.

Examples of zwitterionic surfactants include lauryl trimethyl ammonium chloride.

The amount of the emulsifier used is preferably 0.01 to 10% by weight, more preferably 0.5 to 5% by weight, based on the polymerizable monomer. If the amount of the emulsifier used is too small, stable emulsion dispersion becomes difficult, and if it is too large, the moisture resistance of the obtained toner is poor.

Stabilizers include polyvinyl alcohol, starch,
There are water-soluble polymers such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, sodium polyacrylate and sodium polymethacrylate, and these are preferably used in an amount of 0 to 1% by weight based on the polymerizable monomer.

Examples of the oil-soluble polymerization initiator include organic peroxides such as benzoyl peroxide and t-butyl perbenzoate, and azobis compounds such as azobisisobutyronitrile and azobisisobutylvaleronitrile.

Examples of water-soluble polymerization initiators include persulfates such as potassium persulfate and amonium persulfate, hydrogen peroxide, 4,4′-
Azobis cyanovaleric acid, 2,2'-azobis (2-amidinopropane) dihydrochloride, t-butyl hydroperoxide, cumene-hydroperoxide and the like can be used.

The water-soluble polymerization initiator may be used in combination with a reducing agent. As the reducing agent, there are commonly known reducing agents such as sodium metabisulfite and ferrous chloride. The reducing agent does not necessarily have to be used, but when used, it is preferably used in an equivalent amount or less with respect to the water-soluble polymerization initiator.

The polymerizable initiator is preferably used in an amount of 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, based on the polymerizable monomer.

Examples of chain transfer agents include alkyl mercaptans such as t-dodecyl mercaptan, lower alkyl xanthogens such as diisopropyl xanthogen, carbon tetrachloride, carbon tetrabromide, etc., and used in an amount of 0 to 2 polymerization% based on the polymerizable monomer. Preferably.

Examples of the coloring agent preferably used in the present invention include pigments and dyes. For example, various carbon blacks, nigrosine dyes (CI No. 50415), aniline blue (CI No. 50405), and chalco oil blue (CI No. azoec Blue3). ), Chrome Yellow (CINo.
14090), Ultramarine Blue (CI No. 771)
03), Dyupon Oil Red (CI No. 2610
5), Orient Oil Red # 330 (CI No.60
505), quinoline yellow (CI No. 47005),
Methylene blue chloride (CI No. 52015), phthalocyanine blue (CI No. 74160), malachite green oxalate (CI No. 4200).
0), Rambu black (CI No. 77266), rose bengal (CI No. 45435), oil black, azo oil black and the like can be used alone or in combination. These colorants may be used in any amount, but for the purpose of obtaining the required concentration and for economic reasons, the amount of the colorant is about 1 to 30% by weight, preferably 5 to 15% by weight in the toner. Used in proportion.

As the pigment or dye, those subjected to various treatments for the purpose of increasing the dispersibility in the polymerization reaction system or the toner of the present invention may be used. Examples of the treatment include treatment with a nigrosine dye (CI No. 50415) using an organic acid such as stearic acid and maleic acid.

Among these colorants, various carbon blacks are particularly preferable for the toner of the present invention, for example, Fannes black, Channel black, thermal black, acetylene black, lamp black and the like. Further, the carbon black may be surface-treated. The surface treatment includes, for example, oxidation treatment using various oxidizing agents such as oxygen, ozone and nitric acid, and surface adsorption treatment with an organic acid ester such as dibutyl phthalate and dioctyl phthalate.

When using carbon black as the colorant, it is preferable to use grafted carbon black. The grafted carbon black is obtained by polymerizing the above polymerizable monomer by a method such as bulk polymerization or solution polymerization in the presence of carbon black. The polymer component of the grafted carbon black is preferably 50% by weight or less, more preferably 30% by weight or less based on the grafted carbon black. The grafted carbon black is
In emulsion polymerization, the dispersion stability is excellent, which is preferable, but when the amount of the polymer component is too large, the viscosity tends to be too high when dispersed in the polymerizable monomer, and the workability is deteriorated. The amount of grafted carbon black used is preferably determined by the amount of carbon black component.

Magnetic powder is used in the production of magnetic toner, which can also serve as a colorant. Preferred magnetic powders include, for example, iron such as magnetite or ferrite, or oxides or compounds of elements exhibiting ferromagnetism such as nickel and cobalt. These magnetic powders have a particle size of 0.
A powder of 01 to 3 μm is preferable, and the surface of the magnetic powder may be treated with a resin, a titanium coupling agent, a silane coupling agent, a higher fatty acid metal salt or the like. These magnetic substances may be contained in the toner in an amount of 20 to 80% by weight, preferably 35 to 70% by weight. Less than this amount may be used as a colorant.

Anti-offset agents are used as needed. The anti-offset agent can be present in the system in various forms during polymerization and incorporated into the toner as a product. Alternatively, it may be added later to the toner of the present invention in which no offset inhibitor is present. As the anti-offset agent,
Various natural waxes, such as carnauba wax, hydrogenated castor oil, low molecular weight olefin polymers, etc. are used in the present invention, but preferably low molecular weight olefin polymerisability is used. As the low molecular weight olefin polymer, a low molecular weight olefin polymer or a copolymer of olefin and a monomer other than olefin is used. here,
As olefin, ethylene, propylene, butene-1
As a monomer other than olefin, there are acrylic acid ester, methacrylic acid ester, and the like. As this low molecular weight olefin polymer, for example, JP-A-55 is used.
Polyalkylenes described in JP-A-153944 and low molecular weight olefin copolymers described in JP-A No. 50-93647 can be used.

The molecular weight of the low molecular weight olefin polymer of the present invention may be one that is included in the concept of low molecular weight that is usually referred to as a high molecular weight compound, but is generally 1,000 to 45,00 in weight average molecular weight (Mw).
0, preferably 2,000 to 6,000.

The low molecular weight polyolefin polymer of the present invention has a softening point of 10
Those having a temperature of 0 to 180 ° C, particularly 130 to 160 ° C are preferable.

The amount of the low molecular weight olefin polymer that can be used in the present invention is not particularly limited, but it is preferably in the range of 0 to 30% by weight based on the weight of the toner, and more preferably 1 to 3%.
0% by weight is used. If the amount of the low molecular weight olefin polymer is too small, the offset effect due to the addition of the low molecular weight olefin polymer does not appear, and if it exceeds 30% by weight, gelation may occur during the polymerization reaction.

Furthermore, a fluidity improver, a cleaning property improver, etc. can be used if necessary. These can be present in the product toner by allowing them to be present in the polymerization reaction system, but are preferably externally added to the product toner afterwards. The content of these is preferably 0% by weight to 3% by weight with respect to the toner of the present invention. As the fluidity improver, silane,
There are titanium, aluminum, calcium, magnesium and magnesium oxides or the above oxides subjected to a hydrophobizing treatment with a titanium coupling agent or a silane coupling agent. The cleaning property improvers include zinc stearate, lithium stearate and There are metal salts of higher fatty acids such as magnesium laurate or aromatic acid esters such as pentaerythritol benzoate.

In the present invention, the so-called charge amount and charge polarity of the product toner can be freely adjusted by selecting the polymerizable monomer and the colorant, but in order to adjust the charge amount and charge polarity to more desired values, A so-called charge control agent may be used in combination with the colorant in the toner of the invention.

The charge control agent preferably used in the present invention includes, for example, Spyron Black TRH and Spyron Black TPH.
(Hodogaya Kagaku) and other azo dyes such as p-fluorobenzoic acid, p-nitrobenzoic acid, and aromatic acid derivatives such as 2,4-di-t-butylsalicylic acid such as dibutyl-tin oxide and dioctyl-tin oxide. Examples thereof include tin compounds. These are preferably used in an amount of 0 to 5% by weight based on the polymerizable monomer.

In the present invention, after the main resin component is produced by polymerization, a coagulant is added to the obtained polymerization liquid (particle dispersion liquid) to solidify the particles. In the present invention, this solidification is performed while heating the glass transition temperature of the main resin component or higher, or the particles are heated to a temperature of the glass transition temperature or higher of the main resin component after solidification (hereinafter, these are referred to as “heat treatment”). )is necessary.

This heat treatment increases the bulk density of the particles and improves the moisture resistance and durability. Especially, the durability is most improved.

The heat treatment temperature is 150 ° C as an upper limit. If this temperature is too high, not only the main resin components are easily deteriorated, but also the heating equipment becomes complicated.

The heat treatment temperature is 25 than the glass transition point of the main resin component.
Temperatures up to ~ 60 ° C are most preferred.

The coagulation can be performed by a method of mixing the polymerization liquid and the coagulant aqueous solution at a constant ratio, a method of gradually dropping the polymerization liquid into the coagulant aqueous solution with stirring, or the like. It can be carried out by heating the mixture.

When heat-treating after solidification, the temperature during solidification is not particularly limited. This heat treatment may be carried out by continuously heating the coagulation liquid after coagulation. When the particles are immediately separated, a washing process or a pulverization process may be optionally inserted and dispersed in an aqueous medium and heated. May be. In some cases, the heat treatment during solidification and the heat treatment after solidification may be used together.

In the above coagulation, the particle size component of the obtained particles is 1 to 10
It is preferable to adjust to 0 μm, especially 3 to 7
It is preferably adjusted to 0 μm, and most preferably adjusted so that particles of 5 to 25 μm are the main component. The average particle size is preferably adjusted to 9 to 15 μm. For this purpose, it is preferable to use the above coagulant in an amount of 0.1 to 5 times the weight of the emulsifier in the polymerization liquid, especially 0.3 to
It is preferable to use 3 times. As a result, the obtained particles can be used as a toner as they are or by simply classifying them, so that the pulverizing step is not necessary, and therefore the drawbacks of the pulverizing toner can be solved. Further, since the toner particles having an imperfect spherical shape are obtained by solidification, the toner particles have excellent cleaning properties.

In the above coagulation, large particles of 100 μm or more may be generated, and in this case, a pulverization step is necessary to obtain a particle size suitable for toner particles. Even in this case, since the heat treatment is performed in the present invention, the bulk density of the particles is increased, and accordingly, the moisture resistance and the durability can be improved. Further, the colorant and / or the magnetic powder and the toner property improving agent used as required solves the drawbacks of the pulverized toner, such as good dispersion in the resin and slight pulverization. be able to.

Examples of the coagulant include inorganic acids such as hydrochloric acid and sulfuric acid, organic acids such as formic acid and oxalic acid, these acids and alkaline earth metals,
There are water-soluble metal salts such as aluminum. Although these coagulants can be used alone or in combination, preferred coagulants are magnesium sulfate, aluminum sulfate, barium chloride, magnesium chloride, calcium chloride, sodium chloride and / or their combination with an inorganic acid. These coagulants are preferably used as an aqueous solution of 0.1 to 10% by weight, particularly 0.1 to 5% by weight.

The liquid obtained through the coagulation step (and heat treatment step) is in the form of a slurry, which can be spin-dried to isolate the particles, which can be further washed and dried, and in some cases After that, it is classified as an electrophotographic toner.

Here, in particular, the washing further removes the emulsifier attached to the toner, and can contribute to the improvement of the charging stability and the blocking property of the toner obtained in the coagulation step.

Washing is preferably done with 40-70 ° C warm water,
It may be less than 40 ° C.

The toners obtained according to the present invention are described in various developing processes such as the cascade developing method described in US Pat. No. 2,618,552, the magnetic brush method described in US Pat. No. 2,874,065, and US Pat. No. 2,221,776. A powder cloud method, a touchdown developing method described in U.S. Pat. No. 3,166,432, a so-called jumping method described in Japanese Patent Laid-Open No. 55-18656, and a so-called magnetic toner manufactured by a crushing method as a carrier. It can be used for a microtoning method, a so-called bipolar magnetic toner method for obtaining a necessary toner charge by frictional charging between magnetic toners, and the like.

Further, the toner obtained by the present invention can be applied to various fixing methods,
For example, it can be used in so-called oilless and oil coating heat roll method, flash method, oven method, pressure fixing method and the like.

Further, the toner of the present invention is used in various cleaning methods,
For example, it can be used for so-called a fur brush method, a blade method and the like.

(Example) Next, the Example of this invention is shown. Hereinafter,% means% by weight.

Example 1 (1) Emulsion dispersion and production of polymerization liquid 100 g of grafted carbon (grafted carbon GP-E-2 manufactured by Ryoyu Kogyo Co., Ltd.) on the stainless beaker of 3.
400 g of styrene as a polymerizable monomer, 120 g of butyl acrylate as a polymerization initiator, 12 g of azobisisobutyronitrile as a polymerization initiator, and 0.6 g of t-dodecyl mercaptan as a chain transfer agent, and a high-speed shear disperser (TK homomixer, special machine). It was mixed and dispersed at 3000 rpm for 30 minutes by Kogyo Co., Ltd.

Next, add 1300g of ion-exchanged water to this carbon dispersion.
As an emulsifier, anionic surfactant sodium dodecylbenzenesulfonate 12 g, nonionic surfactant nonipol PE-68 (Sanyo Chemical Co., Ltd. oxypropylene-oxyethylene block polymer) 3 g
And Neugen EA170 (Daiichi Kogyo Seiyaku Co., Ltd. polyoxyethylene glycol nonyl phenyl ether) 3 g
Add an aqueous solution in which the
After emulsification for a minute, a black pre-emulsion was obtained.

Then, the black pre-emulsion was transferred to a 34-neck separable flask equipped with a stirrer, nitrogen inlet, thermometer, and condenser, and the flask temperature was kept at 80 ° C under a nitrogen stream at 5 ° C.
After polymerizing for a time, it was cooled to obtain a polymerization liquid. The polymerization rate at this time was 99.5% or more. The molecular weight of the polymer was measured by gel chromatography using a standard polystyrene calibration curve. The weight average molecular weight (Mw) was 80,0.
The number average molecular weight (Mn) was 25,000.

(2) Coagulation step / final step While the above polymer solution 1 was sufficiently stirred in 0.3% aqueous MgSO ₄ solution 2 heated to 100 ° C, the temperature of the aqueous solution was maintained at 100 ° C, and the solution was uniformly added dropwise over about 30 minutes. Solidified. The temperature was kept at this temperature for another 30 minutes and cooled to room temperature. Then, this slurry was dehydrated with a centrifugal dehydrator, and then washed repeatedly with hot water at 50 ° C. three times. Then in the dryer 30
Toner was obtained by drying at ~ 35 ° C. When the particle diameter of the obtained toner is measured with a Coulter counter, the particle diameter is 5
˜100 μm, and the average particle size was 19 μm. Further, when the glass transition point (Tg) was measured by a differential scanning calorimeter, it was 73.
It was at ° C. This toner is further processed by a zigzag classifier (10
The product was classified to 5 to 25 μm with 0MZR, manufactured by Alpin Co., Ltd., and the yield was 85% of that before classification. Also in the following Examples and Comparative Examples, the particle size and average particle size were measured with a Coulter counter, the glass transition point was measured with a differential scanning calorimeter, and the classification was performed with a zigzag classifier.

Examples 2 to 4 and Comparative Examples 1 to 2 Polymerization liquid 1 obtained in Example 1 was added to a coagulant aqueous solution (shown in Table 1) heated to the coagulation temperature shown in Table 1 to about 30.
The solution was uniformly added dropwise over a period of minutes and solidified. During the solidification, the solidification temperature was maintained, and after the addition of the solidification polymerization solution was completed, the solidification temperature was maintained at the same temperature for 30 minutes and then cooled to room temperature.
The obtained coagulation liquid (slurry) was dehydrated with a centrifugal dehydrator, and then washed 3 times with warm water at 50 ° C. Then 30-35 ° C
To obtain toner particles. The particle diameter of the toner particles, the average particle diameter, the yield of particles having a particle size of 5 to 25 μm, and the glass transition point of the main resin component are shown in Table 1 together with the results of Example 1.

A plain paper copier (u-Bix1600, manufactured by Konishi Roku Photo Industry Co., Ltd.) using the classified toners obtained in Examples 1 to 4 and Comparative Examples 1 and 2 and using a commercially available insulating carrier was used. The electrophotographic toner properties were tested. However, each toner was subjected to external addition treatment of hydrophobic silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) and zinc stearate as fluidity improvers by 0.6% and 0.1% to the toner, respectively. The test results are shown in Table 1.

Example 5 (1) Emulsion dispersion and production process of polymerization solution 100 g of grafted carbon, 360 g of styrene, 180 g of butyl methacrylate, 6 g of methacrylic acid, 0.6 g of t-dodecyl mercaptan, 5.2 g of benzoyl peroxide as a polymerization initiator and low Molecular weight polypropylene (Viscole 550P, trade name of Sanyo Kasei Co., Ltd.)
6g was mixed and dispersed with a high-speed shearing disperser (TK Homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.) at 3000r.pm for 30 minutes. Then, 1500g of ion-exchanged water, 18g of tonalium dodecylbenzenesulfonate, and nonionic surfactant Agent Nonipol PE-68 (trade name of Sanyo Chemical Industry Co., Ltd.) 4 g,
An aqueous solution in which 4 g of the nonionic surfactant Neugen EA170 (trade name of Dai-ichi Kogyo Seiyaku Co., Ltd.) was dissolved was added to a high-speed shearing disperser and emulsified at room temperature at 3000 rpm for 30 minutes to obtain a black pre-emulsion.

This black pre-emulsion was transferred to a three-four-neck separable flask, polymerized at 70 ° C. for 5 hours in a nitrogen stream, and then cooled to obtain a polymerization solution.

The polymerization rate at this time was 99.5% or more, and the molecular weight of the polymer obtained in the same manner as in Example 1 was Mw 86,000 and Mn 51,000.

(2) Coagulation Step / Final Step Using the coagulant aqueous solution and the coagulation temperature shown in Table 3, toner particles were obtained in the same manner as in Examples 1 to 4.

Example 6 A toner was obtained by carrying out the coagulation step and the final step in the same manner as in Examples 5 to 7, depending on the polymerization liquid 1 obtained in Example 5, the coagulant aqueous solution shown in Table 3, the coagulation temperature and the heat treatment temperature. .

The toner particle diameters obtained in Examples 5 and 6, the average particle diameter, 5
Table 2 shows the yield of particles of .about.25 .mu.m, the glass transition point of the main resin component, and the electrophotographic characteristics tested in the same manner as in Examples 1 to 4.

Comparative Example 3 (Production of Toner by Suspension Polymerization) 70 g of styrene, 30 g of butyl methacrylate, 15 g of grafted carbon and 2 g of benzoyl peroxide were sufficiently kneaded with a homomixer, and 500 g of a 3% calcium phosphate 1% aqueous solution was added, and further homomixer Dispersed for 30 minutes at 3000 rpm.

This dispersion was transferred to a flask and suspension polymerization was carried out at 80 ° C for 7 hours. The polymerization rate was 99% or more. This polymer was dehydrated, washed with an aqueous hydrochloric acid solution having a pH of 2 or less, and then dried to obtain a toner. The resin of this toner had Mw of 110,000 and Mn of 50,000.

Comparative Example 4 (Production of Toner by Emulsion Polymerization and Spray Drying) In Example 1, 12 g of ammonium persulfate was dissolved in ion-exchanged water together with an emulsifier instead of 12 g of azobisisobutyronitrile. The emulsion polymerization liquid obtained according to Example 1 (1) was spray-dried at a temperature of 110 ° C. to obtain a toner.

Comparative Example 5 (Pulverizing method) Styrene / butyl methacrylate = 70/30 (weight ratio) by solution polymerization using toluene as a solvent, molecular weight Mw 70,000 and
A polymer of Mn 30,000 was prepared, and the solvent was removed under reduced pressure to remove toluene to form a white solid. To 1,000 g of this polymer, 50 g of carbon black, 10 g of phthalocyanine copper, and 20 g of low molecular weight polypropylene (Viscor 550P, trade name of Sanyo Kasei Co., Ltd.) were kneaded with a two-roll mill and pulverized with a jet mill to obtain a toner.

Comparative Example 6 The procedure of Example 13 was repeated, except that 10 g of a 1% aqueous solution of polyvinyl alcohol was added and the heat treatment at 100 ° C. for 30 minutes was omitted.

The toner particles obtained in Comparative Examples 3 to 6 had a particle size, an average particle size of 5,
Table 3 shows yields of particles of -25 μm, glass transition points of main resin components, and electrophotographic characteristics tested in the same manner as in Examples 1 to 4.
Shown in.

The electrophotographic characteristics in Examples 1 to 6 and Comparative Examples 1 to 6 were evaluated as follows.

(a) Resolution: Electrophotographic Society Test Chart No. 1 was used to make a copy on plain paper using each developer.
The copied image was evaluated by comparing whether the image could be read in detail.

(b) Image density: The density of the black portion of the copied paper was measured with a densitometer and judged in the same manner as the resolution.

(c) Gradation: As in the case of resolution, evaluation was performed using the shaded area divided into 11 stages in the central portion of the test chart.

(d) Cleaning property: Each of the developed developers was continuously copied using a copying machine under the conditions of a temperature of 30 ° C. and a humidity of 80% RH, and evaluated by the number of copies until defective cleaning occurred.

(e) Blotting property: The toners prepared in Examples 1 to 14 and Comparative Examples 1 to 3 were allowed to stand for 72 hours under the conditions of 50 ° C. and 95% humidity, and it was judged whether or not the toner was blocked. ⊚: Very Excellent ◯: Excellent Δ: Slightly inferior ×: Inferior

(f) Charge stability: Each developer was stirred with a copying machine and the charge amount was measured for a certain period of time and the change was judged by the change in charge amount. ◎: Very good ○: Excellent △: Slightly inferior X: evaluated as inferior.

(g) Durability: 100,000 sheets were continuously copied from each of the prepared developers under the conditions of a temperature of 30 ° C. and a humidity of 80% RH using a copying machine. The scattering of the toner generated at this time was examined and evaluated according to the following evaluation.

A: There is no toner scattering.

◯: Some scattering of toner is seen.

Δ: A large amount of toner is scattered.

X: A large amount of toner is scattered.

(h) Moisture resistance: Each of the toners prepared was dried at 25 ° C and a humidity of 98.
The sample is allowed to stand for 24 hours under the condition of%, and the ratio of the weight increase after humidification to the weight before humidification is shown in%.

(Effects of the Invention) By the method for producing an electrophotographic toner according to the present invention, a toner excellent in resolution, image density and gradation, and particularly excellent in durability and moisture resistance can be obtained by using a polymerization method.
Furthermore, by adding the above characteristics, it is possible to obtain a toner excellent in cleaning property, charging stability and blocking property.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Kurumi 4-13-1, Higashimachi, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Plant (72) Inventor Shigeki Tanaka 4-13, Higashimachi, Hitachi City, Ibaraki Prefecture No. 1 Inside the Yamazaki Plant of Hitachi Chemical Co., Ltd. (72) Inventor Takashi Amano 4-13-1 Higashimachi, Hitachi City, Ibaraki Prefecture Inside the Yamazaki Plant of Hitachi Chemical Co., Ltd. (56) Reference JP-A-58-50545 (JP, A) JP-A-56-98202 (JP, A) JP-A-57-45558 (JP, A) JP-A-57-154253 (JP, A) JP-A-56-70556 (JP, A) Kai 60-220358 (JP, A) JP 60-225170 (JP, A) JP 43-10799 (JP, B1) JP 5-45028 (JP, B2)

Claims (2)

[Claims] 1. A polymerizable monomer, a colorant and / or a magnetic powder, and an oil-soluble polymerization initiator or an oil-soluble polymerization initiator and a water-soluble polymerization initiator less than the same weight thereof in the presence of an emulsifier. Emulsified and dispersed in, to polymerize to produce a main resin component, and to add a coagulant to the obtained polymerization liquid to solidify while heating to a temperature not lower than the glass transition point of the main resin component and not higher than 150 ° C.
Alternatively, a coagulant is added to the obtained polymerization liquid to coagulate the particles, and the particles obtained thereafter are added to the glass transition point of the main resin component or above 150
A method for producing a toner for electrophotography, which comprises heating to below ℃. 2. The method for producing an electrophotographic toner according to claim 1, wherein at the time of coagulation, at least one compound selected from inorganic acids, organic acids and water-soluble metal salts thereof is used as a coagulant.