JPS6333753A - Production of toner for electrophotography - Google Patents

Abstract

PURPOSE:To improve low-temp. fixability and offset resistance by subjecting specific 2-polystyryl ethylacrylate or methacrylate and unsatd. monomer to emulsion polymn. in the presence of a coloring agent and magnetic powder to prepare a main resin component and subjecting the emulsion polymerized liquid to salting out. CONSTITUTION:The 2-polystyryl ethylacrylate or methacrylate expressed by the formula and the unsatd. monomer copolymerizable therewith are subjected to the emulsion polymn. in the presence of the coloring agent and magnetic powder to produce the main resin component and the resultant emulsification polymerized liquid is subjected to the salting out. The emulsion polymn. is progressed until the rate of polymn. attains >=99wt% and the weight average mol.wt. thereof is preferably >=50,000. In the formula, R1 denotes a hydrogen atom or lower alkyl group of 1-6C, R2 denotes a hydrogen atom or methyl group, n denotes 10-200 integer. The toner for electrophotography which has the excellent resolution, image density and gradation characteristic, has the particularly excellent cleanable property, electric charge stability and blocking property and has further the excellent low-temp. fixability and offset resistance and is suitable for dry process development is thus obtd. by making use of the emulsion polymn. method.

Description

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

(Prior art) In electrophotography, after uniformly charging a photoreceptor,
A light image based on the original image is exposed to the photoreceptor to eliminate or reduce the charge on the light irradiated area to form an electrostatic latent image on the photoreceptor based on the original image, and then a developer containing toner is used. The toner image is made visible. This visualized toner image is transferred to a suitable transfer member and fixed thereon to form a so-called copy.

The developer used in the above process basically contains a coloring agent to visualize the electrostatic latent image and a rejuvenating agent to fix the developed image to the transfer material. 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.

Conventionally, toner for such a dry developer is generally prepared by melting and kneading a colorant such as a carbon blank and/or a magnetic powder such as magnetite in a thermoplastic resin to form a dispersion, and then processing the resulting dispersion using a suitable pulverizer. The toner has been produced by applying mechanical impact force to crush the dispersion to a desired particle size, and if necessary, further classifying it to form a toner.

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

Furthermore, Japanese Patent Publication No. 51-14895, Japanese Unexamined Patent Publication No. 57-5
No. 3,756, etc., proposes a method for producing toner using a suspension polymerization method. When using the suspension polymerization method, a perfectly spherical toner can be obtained.

(Problems to be Solved by the Invention) The pulverization method not only requires a large amount of energy for melt-kneading and pulverization (but also the produced toner inevitably has many drawbacks).

In particular, when a desirable resin is used in the melt-kneading process and the grinding process, for example, when a resin that easily melts is used, toner aggregation (caking) during storage and fogging due to toner filming on the photoconductor may occur. In addition, if a resin that is easily crushed is used, it will be crushed in the developing device and become fine toner, which will cause image fogging and in-machine leakage in the future.

In addition, the colorant dispersed in the resin appears on the surface of the crushed toner, resulting in a decrease in the amount of triboelectric charge in high humidity conditions and the colorant falling off in the developing machine. This causes undesirable phenomena such as contamination of the surface of the photoreceptor and contamination of the surface of the photoreceptor.

In order to solve these drawbacks of the pulverization method, methods of spray drying an emulsion obtained by emulsion polymerization as described above and methods of producing toner by suspension polymerization have been proposed. It has been found that toners obtained by these methods overcome some of the drawbacks of toners obtained by milling methods, but introduce new drawbacks. That is, since the obtained toner particles are perfectly spherical, the cleaning properties are poor, and since the emulsifier or suspending agent remains in the toner particles, charging stability and blocking properties are reduced.

Furthermore, in electrophotography, after development and transfer, the toner image is
However, conventionally, the transferred toner image is
Melt and set in the oven.

The so-called oven fixing method was the mainstream. However, in recent years, from the viewpoints of downsizing, high-speed copying, and energy saving of copying machines, a shift has been made to a so-called heat roll fixing system in which fixing is performed using a heated roller.

In the conventional oven fixing method, an oligomer resin having a molecular weight of 10,000 or less is used as the toner fixing resin because it needs to melt quickly in the oven. However, in the heat roll fixing method, when such oligomers are used as the fixing resin, a part of the toner adheres to the surface of the fixing roll during fixing, causing a significant offset phenomenon that stains other paper, making it impractical for practical use. cannot be provided.

In order to prevent this off-cent phenomenon, there is a method of applying a mold release liquid such as silicone oil to the fixing roll, but it is mechanically difficult to apply it uniformly, and the mold release liquid is heated. There are problems such as generating odor and increasing the size of the device. In order to prevent offset from occurring in the fixing resin, it is effective to increase the molecular weight of the resin. In the case of polystyrene, which is commonly used as a resin, if the average molecular weight is 50,000 or more, preferably 100,000 or more, heating No offset to roll at all. While I was
If such a high molecular weight resin is used as a fixing resin, there will be a drawback that the toner's fixability to paper or sheets is extremely poor, and once fixed images are bent, rubbed, etc. It has the disadvantage that it easily peels off at knots.

The present invention solves the above-mentioned problems and provides an electrophotographic image suitable for a hot roll fixing method, which has excellent image density, resolution, and gradation, and has particularly excellent low-temperature fixing properties and offset resistance. The purpose of the present invention is to provide a method for producing toner for use in other applications.

(Means for Solving the Problems) The present invention is based on the general formula: [wherein R3 represents a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms, R2 represents a hydrogen atom or a methyl group, and n
represents an integer from 10 to 200] and an unsaturated monomer copolymerizable with these are emulsion-polymerized in the presence of a colorant and/or magnetic powder to obtain a main resin. The present invention relates to a method for producing an electrophotographic toner, which comprises producing components and salting out the obtained emulsion polymerization solution.

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

During this emulsion polymerization, a colorant and/or magnetic powder and a polymerization initiator can be added. In addition, toner property improvers such as an offset inhibitor, a charge control agent, a fluidity improver, and a cleaning performance improver, a stabilizer for assisting emulsification and dispersion, and a chain transfer agent may be appropriately present.

As a method for emulsifying and dispersing the polymerizable monomer in an aqueous medium, the polymerizable monomer, emulsifier, and 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.

The polymerization initiator may be added after this emulsification and dispersion, but
It is preferable to dissolve the water-soluble polymerization initiator in advance in an aqueous medium during emulsification and dispersion. Moreover, as the polymerization initiator, an oil-soluble polymerization initiator can be used in combination, and it is preferable that this is dissolved in advance in the polymerizable monomer.

Furthermore, in order to improve dispersion in the resin, the colorant and/or magnetic powder is preferably used after being dissolved or dispersed in the polymerizable monomer in advance, rather than being added after the emulsification and dispersion. The same applies to toner property improvers used as necessary. Further, a stabilizer may be used as necessary, and it may be added after the emulsification and dispersion, or may be dissolved in the aqueous medium in advance.

Stirring and mixing in the above emulsification dispersion may be carried out by stirring at a relatively high speed using an ordinary stirrer, but it is preferably carried out by stirring by high-speed shearing using a homomixer or the like. This also applies to the case where a colorant and/or magnetic powder and an optional toner property improver are dispersed in the polymerizable monomer.

Emulsion polymerization is carried out after or during emulsion dispersion,
Preferably it is carried out at a temperature of 20 to 120°C, particularly 50 to 80°C.

This emulsion polymerization is preferably carried out until the polymerization rate reaches 99% by weight or more, particularly preferably 99.9% by weight or more. When the polymerization rate is low and there is a large amount of residual toner, the toner properties, especially storage stability, tend to be poor.

Further, the polymer obtained by emulsion polymerization preferably has a weight average molecular weight of so, ooo or more. If the molecular weight becomes too small, cleaning properties and blocking resistance tend to decrease.

Moreover, the obtained polymer has a glass transition point of 30 to 90°C.
The temperature is preferably 50 to 80°C, particularly preferably 50 to 80°C.

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 emulsion polymerization yields particles of about 3 μm or less.

Next, materials used for emulsion polymerization in the present invention will be explained.

General formula: [In the formula, R1 represents a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms, R2 represents a hydrogen atom or a methyl group,
2-polystyrylethyl acrylate or methacrylate represented by -m represents an integer of 10 to 200]
These are called macromolecules, such as Chemlin from Sartomer.
k) Commercialized as 4500.4500B, 4545B, etc. In this general formula, R1 of Chemlink 4500 is C or H.

is a compound in which R2 is CH3 and n is about 120, and is a granular solid with a narrow molecular weight distribution of 13,000 molecular weight. Moreover, Chemlink 4545B has a molecular weight of 4500. By strongly polymerizing this monomer in combination with other copolymerizable monomers, a copolymer having a high molecular weight side chain based on 2-polystyrylethyl acrylate or methacrylate can be obtained.

When such a copolymer is used as a resin component of an electrophotographic toner, it exhibits excellent low-temperature fixing properties, wide range of offset resistance, and high image quality. The amount of the large molecular monomer used is 10 to 98% by weight, preferably 40 to 80% by weight, and if it is less than 10% by weight, the low temperature fixing properties and wide offset resistance that are the objects of the present invention may not be achieved. Not shown. Also, 9
If it exceeds 8% by weight, a sufficient copolymer cannot be obtained.

Other components that can be copolymerized with the above-mentioned large molecular monomers include styrene and its derivatives, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene, vinyl chloride, vinylidene chloride, vinylidene bromide, Vinyl halides such as vinyl bromide and vinyl fluoride, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate, methyl acrylate, ethyl acrylate, propyl acrylate, n-acrylate
Butyl, isobutyl 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, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate , α-methylene aliphatic monocarboxylic acid esters such as diethylaminoethyl acrylate and diethylaminoethyl methacrylate, acrylonitrile, methacrylatetrile, acrylamide, methacrylamide, and in some cases, acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc. Can be used. In addition, 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-vinylpyrrole, N-vinylcarbazole, N-
N-vinyl compounds such as vinyl indole and N-vinylpyrrolidone, and vinylnaphthalene salts can be used alone or in combination of two or more.

Further, as the polymerizable monomer of the present invention, a compound having two or more polymerizable double bonds that serves as a crosslinking agent can also be used in part. For example, aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and derivatives thereof, diethylene carboxylic acid esters such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, N+N −
Divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfite, and compounds having three or more vinyl groups can be used alone or as a mixture. The amount of crosslinking agent used is 0 to 20% based on the total amount of polymerizable monomers.
It is preferably 0 to 5% by weight, especially 0 to 5% by weight.

The aqueous medium used in emulsion polymerization is mainly water. The ratio of the polymerizable monomer to the aqueous medium is preferably 40/60 to 90/10 in weight ratio of the former/latter.

When this ratio is too small, emulsion polymerization becomes difficult, and when this ratio is too large, the yield decreases.

As the emulsifier, anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants can be used. Among these, when producing negatively chargeable toner, anionic surfactants are used,
When producing a positively chargeable toner, it is preferable to use a cationic surfactant. In these cases, in order to improve dispersion stability, it is preferable to use a nonionic surfactant in combination.

Examples of anionic surfactants include fatty acid salts such as sodium oleate and potassium castor oil, alkyl sulfate ester salts such as sodium lauryl sulfate and ammonium lauryl sulfate, alkyl hanzene sulfonates such as sodium dodecyl hanzene sulfonate, and alkylnaphthalenes. sulfonate, sial-F sulfosuccinate, alkyl phosphate ester salt, naphthalene sulfonic acid formalin condensate,
Examples include polyoxyethylene alkyl sulfate salts.

Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene a/lzkylphenol ether, polyoxyethylene fatty acid ester,
Sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, poly-1-diethylenealkylamine,
Examples include glycerin, fat+113n ester, oxyethylene-oxypropylene bronoch 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 the zwitterionic surfactant include lauryltrimethylammonium chloride.

The amount of emulsifier used is 0.01-1 based on the polymerizable monomer.
Preferably it is 0% by weight, especially 0.5 to 5% by weight. If the amount of emulsifier used is too small, stable emulsion polymerization will be difficult, and if it is too large, the resulting toner will have poor moisture resistance.

Stabilizers include polyvinyl alcohol, starch,
There are water-soluble polymers such as methylcellulose, carboxymethylcellulose, and hydroxyethylcellulose, and these are preferably used in an amount of 0 to 1% by weight based on the polymerizable monomer.

Examples of water-soluble polymerization initiators that can be used in the present invention include persulfates such as potassium persulfate and ammonium persulfate;
Hydrogen peroxide, 4.4"-azobiscyanovaleric acid, 2.2
“-azobis(2-amidinopropane) dihydrochloride, t-
Butyl hydroperoxide, cumene hydroperoxide, etc. can be used. In particular, when persulfates are used, sulfate anion radicals (SO
.

The amount used is 0.01 to 10% by weight based on the polymerizable monomer.
, particularly preferably 0.1 to 5% by weight.

If the amount of polymerization initiator is too small, the polymerizable monomer will not be completely polymerized and will remain in the toner, deteriorating the properties of the toner.

As a polymerization initiator, hendiyl peroxide, perbenzoic acid t
- peroxides such as butyl, abbisisobutyronitrile,
An oil-soluble polymerization initiator such as an azo compound such as azobisisobutylvaleronitrile can be used in combination. The oil-soluble polymerization initiator is preferably used in an amount of 100% by weight or less based on the water-soluble polymerization initiator.

The above water-soluble polymerization initiator may be used in combination with a reducing agent. As the pentanant, those known for -m, such as sodium metabisulfite and ferrous chloride, can be used. The reducing agent does not necessarily need to be used, but when it is used, it is preferably used in an amount equal to or less than the amount of the water-soluble polymerization initiator.

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 the amount thereof is O to 4% by weight based on the polymerizable monomer. Preferably used.

Colorants preferably used in the present invention include pigments or dyes, such as various carbon blanks, nigrosine dye (C, 1, Nct 50415), aniline blue (C, 1, 504 (15), calco Oil Blue (C, 1, Arashi azoec Blue 3),
Chrome Yellow (C, I.

14090), ultramarine blue (C, I.

Arashi 77103), DuPont Oil Red (C, I.

t'h26105), Orient Oil Red #330
(C, 1, 60505), Quinoline Yellow (C
, 1, 47005), methylene blue chloride (C
, 1, l11h52015), Phthalocyanine Blue (C, 1, N174160), Malachite Green Off-Salate CC, 1, Arashi 42000) Lamp Black (C, 1, Arashi 77266), Rose Bengal (C, 1,
45435), oil black, azo oil blank, etc. 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, they are used in the toner in proportions ranging from about 1 to 30% by weight, preferably from 5 to 15% by weight.

The pigment or dye may be subjected to various treatments for the purpose of increasing its dispersibility in the polymerization reaction system or in the toner of the present invention. As the treatment, for example, nigrosine dye (C, I.

There is a treatment of N150415) using an organic acid such as stearic acid or maleic acid.

Among these colorants, particularly preferred for the toner of the present invention are various carbon blacks, such as furnace black, channel black, thermal black, acetylene black, lamp black, and the like. Furthermore, the carbon blank may be surface-treated. Examples of surface treatments 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 preferable to use a grafted carbon blank. Grafted carbon black is obtained by polymerizing the above-mentioned polymerizable s-mer by a method such as bulk polymerization or solution polymerization in the presence of a carbon blank. The polymer component of the grafted carbon black is preferably 50% by weight or less, particularly preferably 30% by weight or less, based on the grafted carbon blank. Grafted carbon black is preferable because it has excellent dispersion stability during emulsion polymerization, but if the polymer component is too large, the viscosity tends to become too high when dispersed in a polymerizable monomer. Work efficiency decreases.

The amount of grafted carbon black used is preferably determined by the amount of carbon blank components.

Magnetic powder is used when manufacturing magnetic toners, and it can double as a colorant. Preferred magnetic powders include, for example, iron such as magnetite and ferrite, or oxides or compounds of elements exhibiting ferromagnetism such as nickel and cobalt.

These magnetic powders are preferably in powder form with a particle size of 0.01 to 3 μm, and the surface of the magnetic powder is treated with a resin, a titanium coupling agent, a silane coupling agent, a higher fatty acid metal salt, etc. Good too.

These magnetic substances can be contained in an amount of 20 to 80% by weight, preferably 35 to 70% by weight, based on the toner.

Less than this amount may be used as a coloring agent.

An offset inhibitor is used if necessary.

The offset inhibitor can be present in the system in various forms during polymerization and can be included in the toner product.

Alternatively, the anti-offset agent can be added later to the toner of the present invention in which it is not present. As the offset inhibitor, various natural waxes such as carnauba wax, hydrogenated castor oil, or low molecular weight olefin polymers can be used in the present invention, and preferably low molecular weight olefin polymers are used. As the 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., and monomers other than olefins include acrylic esters, methacrylic esters, etc.

As this low molecular weight olefin polymer, for example, the polyalkylene described in JP-A-55-153944 and the low-molecular-weight olefin copolymer described in JP-A-50-93647 can be used. can.

The molecular weight of the low molecular weight olefin polymer that can be used in the present invention may be one that is included in the concept of low molecular weight (2) in ordinary polymer chemistry, but in terms of -M, the weight average molecular weight (Mw)
1000-45000, preferably 2000-600
0.

The low molecular weight polyolefin polymer that can be used in the present invention is
Those having a softening point of 100 to 180°C, particularly 130 to 160°C are preferred.

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, preferably 1 to 3% by weight based on the weight of the toner.
0% by weight used. If the amount of the low molecular weight olefin polymer is too small, the anti-offset effect due to its addition will not be exhibited, and if it exceeds 30 times %, gelation may occur during the polymerization reaction.

Furthermore, fluidity improvers, cleaning performance improvers, etc. can be used as necessary. These can be present in the polymerization reaction system and can also be present in the product toner, but
Preferably, it is externally added to the product toner afterwards. The content of each of these is 0 to 3% by weight based on the toner of the present invention.
It is preferable that As a fluidity improver, silane,
There are oxides of titanium, aluminum, calcium, magnesium, and magnesium, or those obtained by hydrophobizing the above oxides with a titanium coupling agent or a silane coupling agent. Examples of cleaning performance improvers include zinc stearate, lithium stearate, and These include metal salts of higher fatty acids such as magnesium laurate or aromatic acid esters such as pentaerydrift benzoate.

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

Charge control agents suitably used in the present invention include azo dyes such as Spiron Black TRH and Subiron Black TPH (manufactured by Hodogaya Chemical Co., Ltd.), p-fluorobenzoic acid, p-nitrobenzoic acid, 2,4-di Examples include aromatic acid derivatives such as -t-butylsalicylic acid, tin compounds such as dibutyltin oxide, and dioctyltin oxide. these are,
It is preferably used in an amount of 0 to 5% by weight based on the polymerizable monomer.

In the present invention, after producing the main resin component by emulsion polymerization, a salting-out agent is added to the obtained emulsion polymerization solution to cause salting out.

Salting out results in a particle size distribution of aggregated particles of 1 to 1.
It is preferable to prepare 8 rounds so that the diameter is 00 μm1, especially 3 to 70 μm, and most preferably, the main component is 5 to 25 μm.

The average particle size is preferably adjusted to 9 to 15 μm. For the above adjustment, the salting-out agent is added at a rate of 0.1 to 5 times, preferably 0.1 to 5 times, the weight of the emulsifier in the emulsion polymerization solution.
It is preferable to use 3 to 3 times as much. If the amount of salting-out agent used is too small, salting-out hardening will be insufficient, and if it is too large, k
The moisture resistance of the toner is poor and the average particle size of the particles becomes too large.

In this salting-out process, the emulsion polymerization liquid and the salting-out agent are mixed,
This can be carried out by a method of dropping the emulsion polymerization liquid little by little into the salting-out agent aqueous solution while stirring, or by a method of mixing the salting-out agent aqueous solution and the emulsion polymerization liquid at a constant ratio.

In this salting-out step, the temperature is preferably at least the glass transition point of the main resin component, particularly preferably from 20° C. higher than the glass transition point to 150° C. or lower. Alternatively, in the case of salting out at a temperature below the glass transition point, it is preferable to provide a step of heat treatment at a temperature above the glass transition point.

Such heat treatment increases the bulk density of the particles of the main resin component and improves moisture resistance, offset resistance, and durability.

In the salting-out process, it is possible to add a large amount of salting-out agent to the emulsion polymerization solution to obtain a large coagulate, which is then pulverized to a particle size suitable for toner. Compared to toner, additives can be dispersed uniformly in the resin, but in order to be crushed,
Compared to the toner according to the present invention, the toner has a shape similar to that of the pulverized toner, and thus is inferior in cleaning properties and toner fluidity.

On the other hand, in the method of the present invention, the particles obtained by salting out can be made into toner as is or by just being classified, and the shape of the toner particles can be asymmetrical like the pulverization method toner. It is completely different from a spherical shape, and is not perfectly spherical, but an imperfect spherical shape, so it has excellent cleaning properties.

Examples of salting-out agents 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 salting-out agents can be used alone or in combination, but preferred salting-out agents include magnesium sulfate, aluminum sulfate, barium chloride, magnesium chloride, calcium chloride,
Sodium chloride and/or a combination of these and an inorganic acid. These salting-out agents are preferably used as a 0.1 to 10% by weight aqueous solution, particularly a 0.1 to 5,000% by weight aqueous solution.

After salting out, toner particles can be obtained by centrifugal dehydration, further washing, drying and, if necessary, classification.

Here, washing is preferable in order to completely remove the dispersant adhering to the particles, and thereby, as well as the above-mentioned salting out, charging stability and blocking property can be improved. Washing is preferably carried out with warm water of 40 to 60°C.

Note that the above heat treatment after salting out may be inserted during the washing step or between two or more washing steps.

The toner obtained according to the present invention can be used in various development processes,
For example, the cascade development method described in U.S. Pat. No. 2,618,552, U.S. Pat. No. 2,874,0
The magnetic brush method described in Japanese Patent No. 65, the powder brush method described in U.S. Pat.
Cloud method, touchdown development method described in U.S. Pat.
The so-called jumping method described in Japanese Patent Application No. 656, the so-called micro L-Jung method using magnetic toner produced by a powder method as a carrier, and the so-called bipolar magnetic method in which the necessary toner charge is obtained by frictional charging between magnetic toners. It can be used in toner methods, etc.

Further, the toner obtained according to the present invention can be used in various fixing methods, such as so-called oil-less and oil-coated heated roll methods, flash methods, oven methods, and pressure fixing methods.

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

(Function) In the present invention, by salting out the emulsion polymerization liquid, the particles in the emulsion polymerization liquid are appropriately agglomerated, and have an average particle size larger than that of the particles in the emulsion polymerization liquid, and are imperfectly spherical. hand,
Resin particles suitable for toner can be obtained without the need for pulverization.

This salting-out process yields imperfectly spherical toner particles, so the toner has excellent cleaning properties, and since the salting-out process also removes the emulsifier, anti-blocking properties and charging stability are also improved. Ru.

Furthermore, since the toner obtained by the present invention has a block polymer skeleton as its main resin component, it exhibits low-temperature fixing properties and a wide range of offset resistance.

(Example) Next, the present invention will be described in detail based on Examples, but the present invention is not limited thereto. In addition, "%" in the examples
shall mean "% by weight" unless otherwise specified.

Example 1 (1) Production of emulsion polymerization solution 3! 420 g of Chemlink 4500 (manufactured by Sartomer, molecular weight Mw 13,000) in a stainless steel beaker.
to 180g of n-phytyl methacrylate? Dissolved liquid and grafted carbon (grafted carbon GP-E-2
100 g of Ryoyu Kogyo (manufactured by Kiki, consisting of 30% carbon content, 30% resin content, and 40% styrene), 12 g of low molecular weight polypropylene (Viscol 550P, manufactured by Sanyo Chemical Industries, Ltd., trade name), and t-dodecyl as a chain transfer agent. 0.6 g of mercaptan was mixed and dispersed using a homomixer at 3000 rpm for 30 minutes.

Next, 1300 g of ion-exchanged water was added to this carbon dispersion.
12 g of sodium dodecylbenzenesulfonate, an anionic surfactant, as an emulsifier, and Nonipol PE-68, a nonionic surfactant (manufactured by Sanyo Chemical Industries Ltd., trade name, polyoxypropyl-oxyethylene chloride).
) 3g.

Neugen EA190 (manufactured by Dai-Kogyo Seiyaku, trade name, polyoxyethylene glycol nonylphenyl ether) 3
g and an aqueous solution in which 12 g of ammonium persulfate was dissolved as a polymerization initiator, and the mixture was further heated at 3000 rpm using a homomixer.
The mixture was emulsified at m for 30 minutes to obtain a black pre-emulsion.

Next, the black pre-emulsion was transferred to a No. 31 four-piece removable flask equipped with a stirrer, a nitrogen inlet, a thermometer, and a condenser, and the temperature of the flask was adjusted to 70°C under a nitrogen stream.
After polymerizing at °C for 5 hours, the mixture was cooled to obtain an emulsion polymerization solution. The polymerization rate at this time was 99.9% 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 120,000, and the number average molecular weight (Mn) was 35,000.

(2) Salting out step, final step The above emulsion polymerization solution IIl was uniformly dropped into a 3% magnesium sulfate aqueous solution 12 heated to 60° C. over about 30 minutes with thorough stirring, and salted out. The obtained slurry was transferred to an autoclave and heat-treated at 120°C for 30 minutes. Next, this slurry was dehydrated using a centrifugal dehydrator, and then heated at 50°C.
Washing was repeated three times with warm water. Thereafter, it was dried in a dryer at 30 to 35°C to obtain a toner.

The particle size of the obtained toner was measured using a Coulter counter, and the particle size was 4 to 60 μm, with an average particle size of 14 μm.

Furthermore, when the glass transition point (Tg) was measured using a differential scanning calorimeter, it was 71°C.

When this toner was further classified into 5 to 25 μm using a zigzag classification i (100MZR, manufactured by Alvin Co., Ltd.), the yield was 92% of that before classification.

Also in the following Examples and Comparative Examples, the particle size and average particle size were measured using a Coulter counter, the glass transition point was measured using a differential scanning calorimeter, and the classification was performed using a zigzag classifier.

Example 2 In the same manner as in Example 1, 210 g of Chemlink 4500 (manufactured by Sartomer), 210 g of styrene, 180 g of n-butyl methacrylate, and 100 g of grafted carbon (Graft Carbon GP-E-2, manufactured by Ryoyu Kogyo Kiku) were prepared. An emulsion polymerization solution was obtained in the same manner as in Example 1 using 12 g of low-molecular polypropylene (Viscol 550P, manufactured by Sanyo Chemical Industries, Ltd.) (other components were the same as in Example 1). The polymerization rate is 99.9% or more, and the molecular weight of the polymer is M w
=150.000, Mn=37,000.

Further, salting out and heat treatment were performed in the same manner as in Example 1 to obtain a dried toner.

The obtained toner had a particle size of 3 to 70 μm and an average particle size of 14
μm, Tg was 70°C. Furthermore, the yield upon classification was 90
%Met.

Comparative Example 1 In the same manner as in Example 1, 420 g of styrene, 180 g of n-butyl methacrylate, 100 g of grafted carbon (Graft Carbon GP-E-2, manufactured by Ryoyu Industries) and low molecular weight polypropylene (Viscol 550P, manufactured by Sanyo Chemical Co., Ltd.) An emulsion polymerization solution was obtained in the same manner as in Example 1 using 12 g of (manufactured by Kogyo I) (other components were the same as in Example 1). The polymerization rate is 99.9% or more, and the molecular weight of the polymer is M w =
110,000 and M n -33,000.

Further, salting out and heat treatment were performed in the same manner as in Example 1 to obtain a dried toner.

The obtained toner has a particle size of 2 to 70 μm and an average particle size of 15
μm, Tg was 72°C. Furthermore, the yield upon classification was 85
%Met.

Comparative Example 2 (1) Synthesis of resin In a 31 four-bottle flask equipped with a stirring device, an inert gas inlet, a thermometer, a condenser, and a dropping funnel, 700 g of Chemlink 4500 (manufactured by Sartomer), 300 g of n-butyl methacrylate, and Charge 1000 g of toluene and raise the temperature of the flask to 100°C. Next, a solution prepared by dissolving 6 g of azobisisobutyronitrile in 200 g of toluene is uniformly dropped over 2 hours. After completion of the dropwise addition, the reaction temperature was raised to 110°C and kept at this temperature for 4 hours. The polymerization rate of this resin was 99% or more. The solvent was removed from the obtained polymerization solution using a vacuum desolvation device to obtain a solid resin. The resulting resin has a Tg of 74°C, a MW of 100.000, and a M
n was 30,000.

(2) Manufacture of toner The above resins: 900g Spilon black TRH (manufactured by Odougaya Chemical Co., Ltd.) 30g carbon black #44 (manufactured by Mitsubishi Kasei) 50g low molecular weight polypropylene (manufactured by Sanyo Kasei, Viscol 550 P)
20 g was weighed and mixed in a super mixer. Furthermore, the mixture was melt-kneaded using a twin-screw kneader. Next, after coarse pulverization using a super mixer and hammer mill, and fine pulverization using a jet mill, 5 to 2
The particle size was adjusted to 5 μm. The average particle diameter at this time is 1
It was 4.5 μm.

Using the classified toners obtained in Examples 1 and 2 and Comparative Examples 1 and 2, a plain paper copying machine (
The electrophotographic toner properties were tested using U-Bix1600 (manufactured by Roku Konishi Photo Industry).

However, each toner contains 0.6% and 0.6% of hydrophobic silica (manufactured by Nippon Aerosil ■, R-972) and zinc stearate as fluidity improvers, respectively.
A 1% external addition treatment was performed. The test results are shown in Table 1.

(The following is a margin) Table 1 □Furthermore, the evaluation of the electrophotographic characteristics in Examples 1 to 4 and Comparative Examples 1 to 3 was performed as follows.

(Al Resolution: Using the Electrophotography Society Test Chart No. 1, copies were made on plain paper using the respective developers. Comparisons were made to evaluate whether the copied images could be read in detail.

(bl Image density: The density of the black part of the copied paper was measured with a densitometer in the same manner as the resolution, and the judgment was made.

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

(dl Blocking property: Each of the prepared toners was left for 72 hours at 50° C. and 95% humidity, and it was determined whether or not the toner was blocked. ○: Excellent. ×: Inferior.

tel Charge stability: Each of the prepared developers was stirred in a copying machine, the amount of charge was measured at regular intervals, and the evaluation was made based on the change in the amount of charge. ○: Excellent. ×: Inferior.

(f) Durability: Using a copying machine, each prepared developer was tested at a temperature of 30°C and a humidity of 80% RH for 10,000 hrs.
Continuous copying was performed. The toner scattering that occurs at this time was investigated and judged based on the following evaluation.

◎: No Totona scattering O: Some toner scattering is observed △: A lot of Totona scattering ×: A large amount of toner scattering occurs (g) Fixability: Remove the fuser unit of the copying machine and check the actual fixed toner An image was obtained using a fixing test device consisting of a Teflon coated roll on the upper side and a silicone rubber coated roll on the lower side, and the temperature of the upper roll can be changed at a linear speed of 70/sec, inter-roll pressure Q, and 5 kg f. / cm
The printed area was fixed and the printed area was bent, and the remaining rate of the printed area in the bent area was evaluated as follows.

○: Almost no peeling is observed at the folded part. △: Peeling is present at the folded part. ×: Peeling is present at areas other than the folded part (hl) Offset resistance: Evaluate offset at each temperature using the same equipment as for fixing properties. did.

○: Offset does not occur ×: Offset occurs (1) Cleanability: Using a copying machine, each prepared developer is continuously copied under conditions of a temperature of 30°C and a humidity of 80% RH, and cleaning defects occur. The evaluation was based on the number of copies made.

(Effects of the Invention) According to the present invention, by utilizing the emulsion polymerization method, it is possible to obtain excellent resolution, image density, and gradation, and in particular, to have excellent cleaning performance, charging stability, and blocking property, and furthermore, to achieve low-temperature fixing. It is possible to obtain an electrophotographic toner suitable for dry development that has excellent properties and anti-offset properties.

Claims (1)

[Claims] 1. General formula: ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, R_1 represents a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms, and R_2 represents a hydrogen atom or a methyl group. 2-polystyrylethyl acrylate or methacrylate and an unsaturated monomer copolymerizable therewith are emulsion polymerized in the presence of a colorant and/or magnetic powder. The main resin components are manufactured using
A method for producing an electrophotographic toner, which comprises salting out the obtained emulsion polymerization liquid. 2. The method for producing an electrophotographic toner according to claim 1, wherein salting out is carried out at a temperature equal to or higher than the glass transition point of the polymer, and/or after salting out, heat treatment is performed at a temperature equal to or higher than the glass transition point.