JPS61167956A - Preparation of electrophotographic toner - Google Patents

Abstract

PURPOSE:To obtain superior durability and humidity resistance by emulsifying a water-soluble polymn. initiator in the presence of an emulsifier and solidifying the obtained polymer dispersion at a temp. of its glass transition point or higher, or heating the solidified polymer particles at said temp. or higher. CONSTITUTION:The polymerizable monomer, a colorant and/or a magnetic powder, and an oil-soluble polymerization initiator, and a water-soluble polymerization initiator in an amt. smaller than the former initiator are emulsified in the presence of an emulsifier, and the obtained polymer dispersion is solidified at a temp. of its glass transition point or higher, or the obtained solidified particles are heated to such temps. The polymn. is performed after emulsification or during emulsification operation at a temp. of 20-120 deg.C to attain >=99wt% polymn. yield. The emulsifier is added in an amt. of 0.01-10wt% of the polymerizable monomer, and as a solidifying agent, magnesium sulfate and/or aluminum sulfate and/or an inorg. salt are used in an aq. soln. of 0.1-10wt%, thus permitting the obtained toner to be enhanced in durability and humidity resistance, and the image formed with this toner to be superior in resolution, image density, and gradation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing an electrophotographic toner using a monopolymerization method.

(Prior art) In electrophotography, after uniformly charging a photoreceptor,
The photoreceptor is exposed to a light image based on the original image, and the charge on the light-irradiated area is eliminated or reduced.

Forms an electrostatic latent image on the photoreceptor based on the original image.

Thereafter, it is visualized using a developer containing toner. This visualized toner image is generally transferred to a suitable transfer member and fixed thereon to form a so-called copy.

The developer used in the above process basically consists of a coloring agent to visualize the electrostatic latent image and a binder to fix the developed image to the transfer body. are broadly classified into so-called wet (liquid) developers and dry developers.

Dry developers can be further divided into two-component developers and one-component developers, with the former consisting of a carrier and toner, and the latter consisting only of toner. In other words, a two-component developer is one that obtains toner of opposite polarity to the electrostatic charge image required to develop the electrostatic charge image on the photoconductor by triboelectrically charging the carrier and toner. A one-component developer is one that is charged by friction between the two components or by friction with other members in the developing device.

Conventionally, toner for such a dry developer is generally prepared by melting and kneading a colorant such as carbon black and/or a magnetic powder such as magnetite in a thermoplastic resin to form a dispersion, and then preparing a dispersion using a suitable material. The toner has been manufactured by a method in which the dispersion is pulverized to a desired particle size by mechanically applying an impact force using a pulverizer, and if necessary, it is further classified to form a toner (described below).

This method is called the crushing method).

Furthermore, Japanese Patent Publication No. 10799/1983 proposes a method for producing completely spherical toner particles by spray drying an emulsion obtained by emulsion polymerization.

In addition, as a toner production method using a polymerization method in order to solve the drawbacks of the pulverization method, a toner production method using a suspension polymerization method is described in Japanese Patent Publication No. 14895/1989, Japanese Patent Application Laid-open No. 53756/1983, etc. Proposed. When using the suspension polymerization method, a perfectly spherical toner can be obtained.

(Problems to be Solved by the Invention) However, the pulverization method not only requires a large amount of energy for melt-kneading and pulverization.

The produced toner necessarily has a number of drawbacks.

In particular, when a desirable resin is used in the melt mixing process and the crushing process, 9 For example, when a resin that is easily melted is used, problems such as agglomeration (caking) during toner storage and capri caused by toner filming on the photoconductor may occur. invite the
Furthermore, if a resin that is easily crushed is used, it will be crushed into fine toner particles in the developing machine, resulting in two-image fog and dirt inside the machine.

In addition, the colorant dispersed in the resin appears on the surface of the pulverized toner, which may cause a decrease in the amount of triboelectric charge in high humidity conditions or drop-off of the colorant in the developing machine.
This causes undesirable phenomena such as contamination of the carrier surface and contamination of the photoreceptor surface.

On the other hand, toners obtained using emulsion polymerization, spray drying, and suspension polymerization solve some of the drawbacks of toners obtained by pulverization methods, but it has been found that they cause new drawbacks. Ta. That is, since the emulsifier or suspending agent remains in the toner particles, charging stability and bronking properties are reduced, and the resulting toner particles are perfectly spherical, resulting in poor cleaning properties.

On the other hand, when toner is manufactured by emulsion polymerization.

Although it is possible to recover particles by salting out the emulsion polymerization liquid and pulverize them to an appropriate particle size, this method has the disadvantage that the durability and moisture resistance of the resulting toner are significantly reduced.

As described above, it has not been possible to obtain a fully satisfactory toner using the single polymerization method.

The present invention solves the problems in the conventional toner manufacturing method, and is capable of producing two image densities.

This is an electrophotographic toner that is suitable for dry development and that has excellent resolution, one gradation, particularly durability and moisture resistance, and can improve cleaning performance, charging stability, and blocking performance. The present invention provides a method for manufacturing the same.

(Means for Solving the Problems) The present invention consists of 9 polymerizable monomers, 2 colorants and/or magnetic powders, and an oil-soluble polymerization initiator or an oil-soluble polymerization initiator and a water-soluble polymer having a weight less than the same weight. A polymerization initiator is emulsified and dispersed in the presence of an emulsifier, and the main resin component is produced by double polymerization, and the obtained polymerization liquid is coagulated at a temperature higher than the glass transition point of the main resin component, or the obtained polymer is obtained after coagulation. The present invention relates to a method for producing an electrophotographic toner, which comprises heating the particles to a temperature equal to or higher than the glass transition point of the main resin component.

The polymerization of the polymerizable monomer in the present invention is carried out by emulsifying and dispersing the 9-polymerizable monomer in an aqueous medium containing an emulsifier, and then polymerizing the polymerizable monomer.

During this emulsification and dispersion, a coloring agent and/or magnetic powder, an oil-soluble polymerization initiator, or an oil-soluble polymerization initiator and a water-soluble polymerization initiator in an amount less than this weight are allowed to exist. In addition, toner property improvers such as off-cent prevention agents, charge control agents, fluidity improvers, and cleaning performance improvers, stabilizers for assisting emulsification and dispersion, and chain transfer agents may be appropriately present.

As a method for emulsifying and dispersing the polymerizable monomer in an aqueous medium, the dipolymerizable monomer, the emulsifier, and the aqueous medium may be stirred and mixed simultaneously, or the polymerizable monomer is added to the aqueous medium in which the emulsifier is dissolved. However, they may be mixed by stirring.

As the polymerization initiator, an oil-soluble polymerization initiator is used.
Also, an oil-soluble polymerization initiator and a water-soluble polymerization initiator less than the same weight thereof are used.

When a water-soluble polymerization initiator is used in a large amount as a polymerization initiator, the resulting toner tends to become hygroscopic, and as a result, the toner tends to have a low triboelectric charge amount and image fogging in a high-humidity atmosphere.

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

Furthermore, in order to improve dispersion of the colorant and/or magnetic powder into the resin, it is preferable to use the polymerizable monomers in advance by dissolving or dispersing them, rather than adding them after the above-mentioned dispersion. The same applies to toner property improvers used as necessary. Additionally, stabilizers may be used as needed;
This may be added after the above-mentioned dispersion or may be used after being dissolved in an aqueous medium in advance.

Stirring and mixing in the above dispersion may be performed using an ordinary stirrer at a relatively high speed, but emulsifying equipment such as a high-speed shear disperser, homogenizer, colloid mill, flow jet mixer, ultrasonic emulsifier, or static mixer may be used. It is preferable to use This also applies to the case where a colorant and/or magnetic powder and an optional toner property improver are dispersed in a monopolymerizable monomer.

Polymerization is carried out for 20 minutes after or while emulsifying and dispersing.
Preferably it is carried out at a temperature of -120°C.

In particular, it is preferable to conduct the reaction at a temperature of 50 to 90°C.

This polymerization is preferably carried out until the polymerization rate reaches 99% by weight or more, particularly preferably 99.9% by weight or more. The lower the polymerization rate and the higher the amount of residual monomer, the better the characteristics of the toner.

In particular, storage stability tends to be poor.

Further, the polymer obtained by double polymerization preferably has a weight average molecular weight of 50,000 or more.

If the molecular weight becomes too small, cleaning properties and blocking resistance tend to deteriorate.

Furthermore, the obtained polymer has a glass transition point of 30 to 90°C.
50 to so'c is particularly preferable.

If the glass transition point is too low, blocking resistance tends to decrease, and if it is too high, fixing ability tends to decrease. The glass transition point can be adjusted mainly by selecting the polymerizable monomer to be used.

Such polymerization results in particles of about 3 μm or less.

Next, materials used for 9 polymerization will be explained.

Examples of the polymerizable monomers include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, p-
Ethylstyrene, 214-dimethylstyrene, p-
n-butylstyrene, p-tert-butylstyrene,
p-n-hexylstyrene, p-n octylstyrene, p-n-nonylstyrene.

Styrene/and its derivatives such as p-n-7" silstyrene, p-n-dodecylstyrene, n-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 4-dichlorostyrene, ethylene, propylene, butylene, isobutylene Ethylenically unsaturated monoolefins such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl halides such as vinyl fluoride, vinyl acetate, vinyl propionate.

Vinyl esters such as vinyl benzoate and vinyl butyrate, methyl acrylate, and ethyl acrylate.

n-butyl acrylate, isobutyl acrylate.

Propyl acrylate, n-octyl acrylate.

Dodecyl acrylate, 2-ethylhexyl acrylate,
stearyl acrylate, 2-chloroethyl acrylate,
Phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, methacrylate stearyl acid, phenyl methacrylate, dimethylamine ethyl acrylate, dimethylaminoethyl methacrylate,
α-methylene aliphatic monocarboxylic acid esters such as diethylaminoethyl acrylate and diethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, and acrylamide.

Acrylic acid or methacrylic acid derivatives such as methacrylamide, acrylic @ 2-hydroxyethyl, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyglobyl methacrylate, and in some cases acrylic acid, methacrylic acid, maleic acid, 7mar Acids etc. can also be used.

47'! - Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl inobutyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl inopropenyl ketone, N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, N-vinyl compounds such as N-vinylpyrrolidone, vinylnaphthalene salts, and the like may be used or a combination of two or more thereof may be used. Among these polymerizable monomers, the use of 40 to 100% by weight of styrene or styrene derivatives provides excellent fixing properties when the toner is copied onto paper using an electrophotographic copying device.

Further, as the polymerizable monomer of the present invention, a compound having two or more polymerizable double bonds that can serve as a crosslinking agent can also be used in part. For example, divinylbenzene.

Aromatic divinyl compounds such as divinylnaphthalene and their derivatives, diethylene carboxylic acid esters such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, N,N divinylaniline, divinyl ether , all divinyl compounds such as divinyl sulfite and 3
The above vinyl group-containing compounds can be used alone or as a mixture. The amount of the crosslinking agent used is preferably 0 to 20% by weight, particularly preferably 0 to 5% by weight, based on the total amount of polymerizable monomers.

The aqueous medium used for emulsification and dispersion is mainly water, but in some cases a water-soluble organic solvent such as methanol, ethanol, methyl cellosolve, etc. may be mixed with water.

The water-soluble organic solvent is preferably 10% by weight or less based on water. The weight ratio of the polymerizable monomer to the aqueous medium is preferably 40/60 to 90/10. If this ratio is too small, emulsification and dispersion will be difficult, and if this ratio is too large, the yield will decrease.

As the emulsifier, anionic surfactants, cationic surfactants, zwitterionic surfactants, and nonionic surfactants may be used. this house.

When producing a negatively chargeable toner, it is preferable to use an anionic surfactant, and when producing a positively chargeable toner, it is preferable to use a cationic surfactant. In these cases, it is preferable to use a nonionic surfactant in order to improve the dispersion stability.

Examples of anionic surfactants include fatty acid salts such as sodium oleate and potassium castor oil, alkyl sulfate esters such as sodium lauryl sulfate and ammonium lauryl sulfate, alkylbenzenesulfonate/acid salts of sodium dodecylbenzenesulfonate, and alkylnaphthalenesulfonic acids. salts, dialkyl sulfosuccinates, alkyl phosphate ester salts, s7 sauce/sulfonic acid formalin condensates, polyoxyethylene alkyl sulfate ester salts, and the like.

Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene fatty acid ester, norbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin, fatty acid ester, oxyethylene- Examples include oxypropylene block polymers.

Examples of cationic surfactants include alkylamine salts such as laurylamine acetate and stearylamine acetate, and quaternary ammonium salts such as lacryltrimethylammonium chloride and stearyltrimethylammonium chloride.

Examples of the zwitterionic surfactant include lauryltrimethylammonium chloride.

The amount of emulsifier used is 0.01 to 1 per 9 polymerizable monomers.
0% by weight is preferred, particularly 0.5-5% by weight. If the amount of emulsifier used is too small, stable emulsification and dispersion will be difficult, and if it is too large, the resulting toner will have poor moisture resistance.

Stabilizers include polyvinyl alcohol, starch,
Water-soluble polymers such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, sodium acrylate, and sodium polymethacrylate are preferably used in an amount of 0 to 1% by weight based on the monomerizable monomer. .

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

Examples of water-soluble polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide, 4.4
'-azobiscyanovalericand, sz-azobis(2-amidinopropane) dihydrochloride, t-butyl hydroperoxide, cumene hydroperoxide, etc. can be used.

The above 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. Although it is not necessary to use a reducing agent.

When used, it is preferably used in an amount equal to or less than the amount of the water-soluble polymerization initiator.

The amount of polymerization initiator is 0.01 to 10 per 9 polymerizable monomers.
Weight ts is preferably used, especially from 0.1 to SXt
Arrogant is preferable.

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. Preferably used.

Colorants preferably used in the present invention include:

Pigments or dyes may be mentioned, for example various carbon blanks, nigrosine dyes (C, 1, & 50415
), aniline blue (C,1,&5O4os).

Calco oil blue (C, LNa azoec Blu
e3)t Chrome Yellow (C, 1, Nl 1409
0 ), Ultramarine - (C, 1, N117
7103), DuPont Oil Red (C, 1, N126
105), O9x Toy kV7 Donna 330 (C,
1, Na60505).

Quinoline x o -(C, I, Na47005), l
f ren; l ru ri o rai)” (C, 1, N152015
), 7riC:1'/727puru(C,1,N1
174160), malachite green offsa L/-)
(C, 1, Na42000).

Lamp black (C, 1, Arashi 77266), Rose Bengal (C, 1, N145435), oil black.

Azo oil black and the like can be used alone or in combination. These colorants can be used in any amount, but in order to obtain the required concentration and for economic reasons, the colorants should be present in the toner at about 1 to 30% by weight, preferably 5 to 15% by weight. used in percentages.

The pigment or dye may be subjected to various treatments for the purpose of increasing its dispersibility in the double polymerization reaction system or in the toner of the present invention.

The treatment includes 9, for example, nigrosine dye (C, I).

N150415) is treated with an organic acid such as stearic acid or maleic acid.

Among these colorants, particularly preferred for the toner K of the present invention are carbon blanks such as furnace black, channel black, thermal black, acetylene blank, lamp black, and the like. Furthermore, the carbon black may be surface-treated. As for surface treatment.

Examples include oxidation treatment using various oxidizing agents such as oxygen, ozone, and nitric acid, and surface adsorption treatment with organic acid esters such as dibutyl phthalate and dioctyl phthalate.

When using carbon black as a colorant, it is preferred to use grafted carbon black. Grafted carbon blank.

It is obtained by polymerizing the above-mentioned polymerizable monomers by a method such as bulk polymerization or solution polymerization in the presence of a carbon blank. The polymer component of the grafted carbon blank is
It is preferably 50% by weight or less, particularly preferably 30% by weight or less, based on the grafted carbon blank. Grafted carbon blanks are preferred because they have excellent dispersion stability during emulsion polymerization, but if the polymer acid content is too large, the viscosity tends to become too high when dispersed in polymerizable monomers, resulting in poor workability. descend. The amount of grafted carbon blank to be used is preferably determined by the amount of carbon blank components.

Magnetic powder is used when manufacturing magnetic toner.

This can double as a coloring agent. Preferred magnetic powders include oxides or compounds of iron such as magnetite or ferrite, or ferromagnetic elements such as nickel and cobalt. These magnetic powders are preferably powders with a particle size of 0.01 to 3 μm, and the surface of the magnetic powder is resin.

Titanium coupling agent, silane coupling agent.

It may be treated with a higher fatty acid metal salt or the like.

The content of these magnetic substances is 20 to 80% by weight based on the toner.

Preferably, it can be contained in an amount of 35 to 70% by weight. Less than this amount may be used as a second coloring agent.

An offset inhibitor is used as necessary. The anti-offset agent is present in the system in the form of a substance during polymerization and can be incorporated into the toner product. Alternatively, it can be added later to the toner of the present invention in which no offset inhibitor is present.

1 various natural waxes as the offset prevention agent,
For example carnauba wax, hardened and mustard oil.

Although low molecular weight olefin polymers and the like can be used in the present invention, low molecular weight olefin polymerizable ones are preferably used.

As this low molecular weight olefin polymer, a low molecular weight polymer of olefin or a copolymer of an olefin and a monomer other than olefin is used. Here, olefins include ethylene, propylene, butene-1, etc.
Acrylic acid ester is a monomer other than olefin.

Examples include methacrylic acid esters. Examples of this low molecular weight olefin polymer include 2, for example, JP-A-55-15394
Polyalkylene described in Publication No. 4, JP-A-50-9
A low molecular weight olefin copolymer described in Japanese Patent No. 3647 can be used.

The molecular weight of the low molecular weight olefin polymer of the present invention may be anything that is included in the concept of low molecular weight in ordinary polymer compounds, but generally the weight average molecular weight (Mw) is 1.00.
0~45,000. Preferably, the number is 000 to 6,000.

The low molecular weight polyolefin polymer of the present invention has a softening point of io
o to 180°C, particularly preferably 130 to 160°C.

The amount of the low molecular weight olefin polymer that can be used in the present invention is not particularly limited, but is preferably in the range of 0 to 30% by weight based on the weight of the toner.

More preferably, 1 to 30 layers are valuable. If the amount of the low molecular weight olefin polymer is too small, the offset effect due to K will not be produced by adding it, and if it exceeds 30% by weight, gelation may occur during the polymerization reaction.

Furthermore, a fluidity improver, a cleaning performance improver, etc. can be used as necessary. These can be present in the polymerization reaction system and then present in the product toner, but preferably they are externally added to the product toner afterwards. The content of each of these is 0''I for the toner of the present invention.
LJi:% to 3% by weight is preferred. Fluidity improvers include
Silane, titanium.

There are oxides of aluminum, calcium, magnesium, and magnesium, or those obtained by hydrophobizing the above oxides with a titanium coupling agent or a silane coupling agent. Cleaning performance improvers include zinc stearate, lithium stearate, and lauric acid. These include metal salts of higher fatty acids such as magnesium or aromatic esters such as pentaerythritol benzoate.

In the present invention, by selecting the polymerizable monomer and colorant, the so-called charge amount and charge polarity of the product toner can be freely adjusted. A so-called charge control agent can also be used in the toner of the invention in combination with the colorant.

Examples of charge control agents preferably used in the present invention include 9, Suviron Blank TR, H, Spiron Blank TPH,
Azo dyes such as (Hodogaya Chemical) 2 For example, p-fluorobenzoic acid, p-nitrobenzoic acid.

2. Aromatic acid derivatives such as 4-di-t-butylsalicylic acid 1 For example, tin compounds such as dibutyl-tin oxide and dioctyl-tin oxide.

These are preferably used in an amount of 0 to 5% by weight based on the dipolymerizable monomer.

In the present invention, after the main resin component is produced by double polymerization, a coagulant is added to the obtained polymerization liquid (particle dispersion) to coagulate the particles. In the present invention.

This solidification is performed at a temperature higher than the glass transition point of the main resin component, or the particles are heated to a temperature higher than the glass transition point of the main resin component after solidification (hereinafter referred to as "heat treatment").
) is necessary.

This heat treatment increases the bulk density of the two particles, improving moisture resistance and durability. In particular, durability is best improved.

The upper limit of the heat treatment temperature is preferably 150°C.

If this temperature is too high, not only will the main resin components be susceptible to deterioration, but the heating equipment will also become complicated.

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

The above-mentioned coagulation (6) can be carried out by mixing the polymerization solution 1 and the coagulant aqueous solution at a fixed ratio, or by dropping the polymerization solution little by little into the coagulant aqueous solution while stirring. This can be done by heating the mixture produced in the operation.

When heat treatment is performed after solidification, the temperature during solidification is not particularly limited. This heat treatment may be carried out by continuously heating the coagulated liquid after solidification, or it may be carried out by once separating the 9 particles, inserting a washing step or a crushing step depending on the case, and dispersing them in an aqueous medium and heating them. . Further, depending on the case, heat treatment during solidification and heat treatment after solidification may be used in combination.

In the above coagulation, the particle size component of the obtained particles is 1 to 10
It is preferable to adjust it to 0 μm, especially 3 to 7
It is preferable to adjust to 0 μmK.

It is most preferable to adjust the particle size so that the main component is particles of 5 to 25 μm. In addition, the average particle size is 9 to 15 μmK
Preferably, it is regulated. For this purpose, it is preferable to use the coagulant in an amount of 0.1 to 5 times the weight of the emulsifier in the polymerization solution, particularly preferably 0.3 to 3 times the weight of the emulsifier in the polymerization solution. As a result, the obtained particles can be made into a toner as they are or by only being classified into 9 parts, thereby eliminating the need for a pulverization step and thus solving the drawbacks of toners produced by the pulverization method. Moreover, since toner particles having an incompletely spherical shape are obtained by coagulation, the toner particles have excellent cleaning properties.

In the above coagulation, large particles of 100 μm or more may be produced, in which case a pulverization step is necessary to obtain a particle size suitable for toner particles.

Even in this case, since heat treatment is applied in the present invention, the bulk density of the particles can be increased, and therefore the moisture resistance and durability can be improved. In addition, 9 colorants and/or magnetic powders and toner property improvers used as necessary are:
It is possible to solve the disadvantages of the pulverization method toner, such as good dispersion in the resin and the fact that only a slight amount of pulverization is required.

Examples of coagulants include inorganic acids such as hydrochloric acid and sulfuric acid, organic acids such as formic acid and oxalic acid, and water-soluble metal salts of these acids and alkaline earth metals, aluminum, and the like. These coagulants can be used alone or in combination, but preferred coagulants are magnesium sulfate, aluminum sulfate, barium chloride, magnesium chloride, calcium chloride, sodium chloride, and/or a combination of these and an inorganic acid. The content of these coagulants is 0.1 to 10% by weight.

It is preferably used as an aqueous solution, particularly a 0.1 to 5% by weight aqueous solution.

The liquid obtained through the coagulation process (and heat treatment process) is in the form of a slurry, which can be centrifugally dehydrated to isolate particles, which are further washed, dried, and optionally classified. do.

It is considered to be a toner for electrophotography.

Here, in particular, washing further removes the emulsifier adhering to the toner, which can contribute to improving the charging stability and blocking property of the toner obtained in the above-mentioned coagulation step.

Washing is preferably carried out with warm water of 40 to 70°C,
The temperature may be lower than 40°C.

The toners obtained according to the present invention can be used in various development processes, such as the cascade development method described in U.S. Pat. No. 2,618,552, and the magnetic brush method described in U.S. Pat. No. 2,874,065.

The powder cloud method described in U.S. Pat. No. 2,221,776, the touchdown method described in U.S. Pat. No. 3,166,432, and the so-called jumping method described in Publication No. 18656/1983. The so-called microtoning method uses magnetic toner produced by a pulverization method as a carrier.

It can be used in the so-called bipolar magnetic toner method in which the necessary toner charge is obtained by frictional charging between magnetic toners.

In addition, the toner obtained according to the present invention has a moderate fixing method9.
For example, it can be used in so-called oil-less and oil-coated heat roll methods, flash methods, open methods, pressure fixing methods, and the like.

Furthermore, the toner of the present invention can be cleaned using various cleaning methods.
For example, traps such as the so-called fur brush method and blade method can be used.

(Example) Next, an example of the present invention will be shown. The following 9% means weight SL.

Example 1 (1) Emulsification dispersion and production of polymerization liquid In a stainless steel beaker of 31, 100 g of grafted carbon (Craft Carbon GP-E-2 manufactured by Ryoyu Kogyo ■) was added as polymerizable monomers: styrene 4009° butyl acrylate 120 g 12 g of azobisinobutyronitrile as a polymerization initiator and 0.6 g of t-dodecyl mercaptan as a chain transfer agent were ao o o r, p, m
The mixture was mixed and dispersed for 30 minutes.

Next, ion exchange water 13009 was added to this carbon dispersion.
Anionic surfactant Sodium Dodecylbenzenesulfonate 129, nonionic surfactant Noniball PE-68 (Sanyo Chemical Co., Ltd. oxypropylene-oxyethylene block polymer) 3 g, and Neugen EA170 (Daiichi Kogyo Seiyaku Co., Ltd.) were used as emulsifiers. An aqueous solution in which 3st polyoxyethylene glycol nonylphenyl ether) was dissolved was added and emulsified for another 30 minutes using a high-speed shear disperser to obtain a black pre-emulsion.

Next, a 3I with a stirring device, nitrogen inlet, thermometer, and condenser! The black bra emulsion was transferred to four separable flasks, and the flask was polymerized at a temperature of 80° C. for 5 hours under a nitrogen stream, and then cooled to obtain a ridge 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, and the weight average molecular weight (Mw) was 80,000. Number average molecular weight (Mn) 25.0
It was 00.

(2) Solidification step/final step Mg5OaO03 in which the above polymerization liquid 11 was heated to 100°C.
Chi aqueous solution 2I! The temperature of the aqueous solution was increased to 10% while stirring thoroughly.
While maintaining the temperature at 0°C, it was uniformly dropped and solidified over about 30 minutes. The mixture was kept at this temperature for an additional 30 minutes and cooled to room temperature. Next, this slurry was dehydrated using a centrifugal dehydrator, and then
Washing was repeated three times with warm water at 0°C. Then, it was dried in a dryer at 30 to 35°C to obtain a toner. When the particle size of the obtained toner was measured using a Coulter counter, the particle size was 5 to 100 μm, and the average particle size was 19 μm. Furthermore, the glass transition point (Tg) was measured with a differential scanning calorimeter and was found to be 73°C. This toner is further divided into 5 to 25μ by a zigzag classifier (100MZR, manufactured by Alpi Co., Ltd.).
When the product was classified into 85 cm, the yield was 85 cm compared to that before classification. In the following Examples and Comparative Examples, the 2nd particle size and the average particle size were measured using a Coulter counter, the glass transition point was measured using a differential scanning calorimeter, and the 1st classification was performed using a zigzag classifier.

Examples 2 to 4 and Comparative Examples 1 to 2 Polymerization liquid 11 obtained in Example 1! 1 to a coagulant aqueous solution (shown in Table 1) heated to the coagulation temperature shown in Table 1.
It was uniformly dropped and solidified in 0 minutes. During coagulation, the above-mentioned coagulation temperature was maintained, and after the completion of dropping the coagulation polymerization liquid, the temperature was maintained at the same temperature as the above-mentioned coagulation temperature for 30 minutes, and then cooled to room temperature. The obtained coagulated liquid (slurry) was dehydrated using a centrifugal dehydrator, and then washed three times with warm water at 50°C. Then 30-35
The toner particles were obtained by drying in a dryer at .degree. The particle size, average particle size, yield of particles of 5 to 25 μm, and glass transition point of the main resin component of this toner particle are shown in Table 1 together with the results of Example 1.

Using the classified toners obtained in Examples 1 to 4 and Comparative Examples 1 to 2, a plain paper copying machine (manufactured by Konishiroku Photo Industry ■, u-Bix 1600) using a commercially available insulating carrier was used. The electrophotographic toner properties were tested. However, each toner was treated with external addition of 0.6% and 0.1% of hydrophobic silica (R-972 manufactured by Nippon Aerosil ■) and zinc stearate as fluidity improvers to the above toner, respectively. did. The test results are shown in Table 1.

Example 5 fl) Manufacturing process of emulsification dispersion and polymerization liquid Grafted carbon 1009. Styrene 3609, butyl methacrylate 1809. 6 g of methacrylic acid, 6 g of t-dodecyl mercaptan O, 5.2 g of benzoyl peroxide as a polymerization initiator, and 6 g of low molecular weight polypropylene (Viscol 550P, Sanyo Chemical Industries ■ trade name) were mixed in a high-speed shear dispersion machine (T, K, Homo Mixer, Tokushu Kika Kogyo ■
After mixing and dispersing for 30 minutes at 300 Q r, p, m (manufactured by Sanyo Kasei Kogyo Co., Ltd.), 18 g of sodium dodecylbenzenesulfonate and the nonionic surfactant Nonipol PE-68 (trade name of Sanyo Kasei Kogyo) 49 were added to 1500 g of ion-exchanged water. ．．
Add the aqueous solution containing the nonionic surfactant Neugen EAI 70 (Daiichi Kogyo Seiyaku ■ trade name) 49 to a gold-controlled shear disperser and emulsify at room temperature for 30 minutes at 300 Or, I) m to form a black pre-emulsion. Obtained.

This black pre-emulsion 't3I! The mixture was transferred to four separable flasks, polymerized at 70° C. for 5 hours under 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 determined in the same manner as in Example 1 was 86.000.
Mn was 51,000.

(2) Solidification process/final process According to the coagulant aqueous solution and coagulation temperature shown in Table 3.

Toner particles were obtained in the same manner as in Examples 1 to 4.

Example 6 Polymerization liquid II obtained in Example 5! 2 The coagulation step and final step were carried out in the same manner as in Examples 5 to 7 using the aqueous coagulant solution, coagulation temperature, and heat treatment temperature shown in Table 3 to obtain toner.

Particle size and average particle size of toners obtained in Examples 5 and 6, 5
Table 2 shows the yield of particles of ~25 μm, the glass transition temperature of the main resin component, and the electrophotographic properties tested in the same manner as in Examples 1-4.

Table 2 Properties Comparative Example 3 (Production of toner by suspension polymerization) Styrene 70
9. Butyl methacrylate 30g.

Thoroughly knead 15 g of grafted carbon and 2 g of benzoyl peroxide in a homomixer, and add 1 g of trivalent lucium phosphate.
% aqueous solution SOOG and mix with a homomixer for another 3000
Dispersion was carried out for 30 minutes at r, p, m.

This dispersion was transferred to a tube flask and subjected to suspension polymerization 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 dried to obtain a toner. The Mw of the resin in this toner is 110.000. Mn was 50,000.

Comparative Example 4 (Manufacture of toner by spray drying after emulsion polymerization) Example 1 except that in place of azobisisobutyronitrile 129, 12 g of ammonium persulfate was dissolved in ion-exchanged water together with an emulsifier. An emulsion polymerization solution obtained according to (1) of Example 1 was spray-dried at a temperature of 110° C. to obtain a toner.

Comparative Example 5 (Crushing method) Styrene/butyl methacrylate - 70/30 (weight ratio) 2 molecules jtMw 70 by bath polymerization using toluene as a solvent
,000 and Mn 30,000 (7).

The solvent was removed under reduced pressure to remove toluene and a white solid was produced. Carbon blank 5 is added to 1.000 g of this polymer.
0g, copper phthalocyanine 109. Low molecular weight polypropylene (Viscol 550P, Sanyo Chemical Industries ■trade name) 20
Knead 9 with two rolls.

A toner was obtained by grinding with a jet mill.

Comparative Example 6 The same procedure as in Example 13 was carried out, except that the step of adding polyvinyl alcohol 1-thi aqueous solution 109 and heat-treating at 100'C for 30 minutes was omitted.

Particle size and average particle size of toners obtained in Comparative Examples 3 to 6, 5
Table 3 shows the yield of ~25 μm particles, the glass transition temperature of the main resin components, and the electrophotographic properties tested in the same manner as Examples 1 to 4.
Shown below.

Table 3 Properties Evaluation of electrophotographic properties in Examples 1 to 6 and Comparative Examples 1 to 6 was performed as follows.

far Resolution: Copying was carried out on plain paper using the electrophotographic society test chart version 1 and the respective developers. We compared and evaluated whether the copied images could be read in detail.

(bl Image density: In the same manner as the resolution, the density of the black part of the copied paper was measured with a densitometer and determined.

(C1 gradation: Evaluated in the same way as the resolution using the 11-level gray area in the center of the test chart.

(d) Cleanability: Each of the prepared developers was continuously copied using a copying machine at a temperature of 30'C and a humidity of 80% RH, and the number of copies until cleaning failure occurred was evaluated.

fe) Blocking property: Examples 1 to 14. The toners prepared in Comparative Examples 1 to 3 were left for 72 hours at 50'C and humidity of 95C to determine whether or not the toners were blocked.

◎: Very good ○: Excellent △: Slightly inferior ×: Inferior It was evaluated as

(f) Charge stability: Each of the prepared developers was stirred in a copying machine, the amount of charge was measured at regular intervals, and judgment was made based on the change in the amount of charge.

◎: Very good ○: Excellent △: Slightly inferior ×: Inferior It was evaluated as

fgl Durability: Using a copying machine, the respective developers were tested at a temperature of 30°C and a humidity of 80% R and H for 10 minutes.
OOContinuous copying of 0 sheets was performed. The scattering of toner that occurs at this time was investigated and judged based on the following evaluation.

◎: No toner scattering.

○: Slight scattering of toner is observed.

△: There is a lot of toner scattering.

X: A large amount of toner scatters.

(h) Moisture resistance: 25% of each prepared toner
The sample was left to stand for 24 hours at a temperature of 98% humidity, and the weight increase after humidification relative to the weight before humidification is indicated by C.

(Effects of the Invention) The method for producing an electrophotographic toner according to the present invention provides excellent resolution, 9 image density, and 9 gradations.

In particular, a toner with excellent durability and moisture resistance can be obtained using a polymerization method. Furthermore, in addition to the above properties, it is also possible to obtain a toner that has excellent cleaning properties, charging stability, and blocking properties.

Claims (1)

[Claims] 1. Polymerizable monomers, colorants and/or magnetic powders, and oil-soluble polymerization initiators or oil-soluble polymerization initiators and less than the same weight of water-soluble polymerization initiators as emulsifiers. The main resin component is produced by emulsifying and dispersing in the presence of the main resin component and polymerizing the main resin component, and the resulting polymer solution is coagulated at a temperature higher than the glass transition point of the main resin component, or the particles obtained after coagulation are used as the main resin component. A method for producing an electrophotographic toner, which comprises heating the components to a temperature above the glass transition point. 2. The method for producing an electrophotographic toner according to claim 1, wherein at least one compound selected from inorganic acids, organic acids, and water-soluble metal salts thereof is used as a coagulant during coagulation.