JPH0675211B2 - Method of manufacturing toner for electrophotography - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an electrophotographic toner 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-mentioned 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. They 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 by 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 using an appropriate pulverizer. Has been manufactured by a method of mechanically applying an impact force to pulverize the dispersion to a desired particle size, and if necessary, classifying the dispersion to obtain a toner (hereinafter, this method is referred to as a pulverization method). .

Further, Japanese Patent Publication No. 43-10799 proposes a method of 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 explain the drawbacks of the pulverization method, a method for producing a toner by a suspension polymerization method is disclosed in JP-B-51-14895 and JP-A-57-53756. Proposed. When the suspension polymerization method is used, a spherical toner is obtained.

Conventionally, the toner obtained by using such a polymerization method is
Although some of the drawbacks of the toner obtained by the pulverization method have been solved, it has been found that they cause new drawbacks. That is, since the obtained toner particles are spherical, the cleaning property is poor, and the emulsifying agent or the suspending agent remains in the toner particles, so that the charging stability and the blocking property are deteriorated.

Generally, in electrophotography, various methods such as a heat roll method, a pressure fixing method, a high frequency heating method, and a flash method are known as the fixing method of the electrostatic image, but the heat roller method is the most general method at present. .

In this heat roll fixing method, the temperature of the heat roll is usually used within a temperature range of 150 to 220 ° C. due to the melting characteristics of the binder resin of the toner, economical efficiency such as power consumption, and copying speed. The binder resin of the toner used in this method is preferably one having a low glass transition point or a low molecular weight from the viewpoint of fixability. However, it is impossible to make the glass transition point too low from the viewpoint of storage stability of the toner,
Limited to above a certain temperature.

Further, when a resin having a low molecular weight is used, a phenomenon called a normal offset in which toner is transferred from the image support to the heating roll during fixing and adheres easily occurs. In addition, the mechanical strength of the toner is disadvantageous.

Various methods have been proposed to prevent such offset phenomenon, and one of them is to add a resin mainly containing polyolefin to the toner in order to increase the releasability of the toner.

Even when a toner is produced by a suspension polymerization method, a method of adding an offset inhibitor at the time of polymerization is disclosed in JP-A-59-13731. However, in this method, the offset inhibitor is a constituent molecule of the toner. Since it is more hydrophobic than the styrene-acrylic resin, it is localized at the core of the toner particles, and is hardly present on or near the surface of the particles, and the offset resistance effect is not so expressed.

As another offset prevention method, a technique for expanding the molecular weight distribution is known. For example, in JP-A-50-134652, a method in which a resin having a weight-average molecular weight and a number-average molecular weight ratio of 3.5 to 40 is used as a binder resin, and in JP-A-49-101031, a crosslinking agent is added to cause a reaction. A method of using the vinyl polymer as a binder resin is disclosed.

(Problems to be Solved by the Invention) However, it is difficult to control the molecular weight distribution within a desired range as described above, particularly in the case of a polymerization toner, because the system is complicated.

Although the method using a cross-linking agent is effective in preventing the offset phenomenon, it has been found that in the polymerized toner, the production rate of low molecular weight substances is small and the fixing property is remarkably lowered.

The present invention solves such problems in the conventional toner manufacturing method and is excellent in image density, resolution, gradation, cleaning property, charging stability, and blocking property, and particularly, fixing property and offset resistance. Provided is a method for producing an electrophotographic toner having excellent properties suitable for dry development, which is suitable for dry development, using a polymerization method.

(Means for Solving Problems) The present invention is to dissolve a vinyl polymer having a weight average molecular weight of 1,000 to 50,000 in an amount of 5 to 200 parts by weight in 100 parts by weight of a polymerizable monomer, and then coloring and / or Emulsified and dispersed in the presence of magnetic powder,
Polymerizing to produce a main resin component, adding a coagulant to the obtained polymerization liquid to coagulate the particles in the polymerization liquid to a particle size suitable for a toner, and to prepare a dispersion liquid of an offset inhibitor. Addition of an offset preventive agent to the toner during the polymerization until the polymerization rate is 90% by weight or more until the completion of the polymerization, after the completion of the polymerization and before the coagulation and / or after the coagulation and before the dehydration. And a method for producing an electrophotographic toner.

The vinyl-type monomer in the present invention is obtained by uniformly dissolving the vinyl-type polymer, and then emulsified and polymerized in an aqueous medium in the presence of a colorant and / or magnetic powder.

At the time of this polymerization, a toner property improving agent such as a charge control agent, a fluidity improving agent, a cleaning property improving agent, a stabilizer for assisting emulsion dispersion, and a chain transfer agent can be appropriately present.

As a method for emulsifying and dispersing the polymerizable monomer in which the vinyl polymer is dissolved in the aqueous medium, the polymerizable monomer in which the vinyl polymer is dissolved, the emulsifier and the aqueous medium are stirred and mixed at the same time. Alternatively, the polymerizable monomer in which the vinyl polymer is dissolved may be added to the aqueous medium in which the emulsifier is dissolved, and mixed by stirring.

As the polymerization initiator used for the polymerization, a water-soluble polymerization initiator or an oil-soluble polymerization initiator is used, and these may be used in combination. The polymerization initiator may be added after emulsification and dispersion. However, it is preferable that the water-soluble polymerization initiator is dissolved in an aqueous medium in advance at the time of emulsification and dispersion. It is preferable to dissolve in the monomer beforehand. In particular, it is preferable to use an oil-soluble polymerization initiator and a water-soluble polymerization initiator together.

Further, in order to improve the dispersion in the resin, the colorant and / or the 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 the toner property improver used as necessary. Further, the stabilizer may be used if necessary, and it may be added after the emulsification and dispersion, or may be dissolved in an aqueous medium in advance and used.

The stirring and mixing in the above emulsification and dispersion may be carried out at a relatively high speed using an ordinary stirrer, but it is preferable to carry out the stirring by high speed shearing using a homomixer or the like.
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.

The obtained polymer preferably has a glass transition point of 30 to 90 ° C, particularly 50 to 80 ° C. If the glass transition point is too low, the blocking resistance tends to decrease, and if the glass transition point 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-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene and p-tert-butyl. Styrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, p
Styrenes such as -n-decylstyrene, pn-dodecylstyrene, n-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and their derivatives, ethylene, propylene, butylene, isobutylene Such as unsaturated monoolefins, 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, propyl acrylate, acrylic acid n
-Butyl, isobutyl acrylate, pentyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate,
2-chloroethyl acrylate, phenyl acrylate, α
-Methyl chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n methacrylate
-Octyl, dodecyl methacrylate, 2-methacrylic acid
Α- such as ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, etc.
Acrylics such as methylene aliphatic monocarboxylic acid esters, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate. Acids or methacrylic acid derivatives, and optionally acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc. can also be used. Also, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl methyl ketone, vinyl hexyl ketone,
Vinyl ketones such as methyl isopropyl vinyl ketone, N
-N-vinyl compounds such as vinylpyrrole, N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone,
These can be used alone or in combination of two or more such as vinyl naphthalene salt. When 40 to 100% by weight of styrene or a styrene derivative is used among these polymerizable monomers, the fixing property is very excellent when the toner is copied onto paper by an electrophotographic copying machine.

The vinyl-based polymer is a polymer obtained by polymerizing the same monomers as those exemplified as the polymerizable monomer, and in this case, the crosslinking agent is the polymerizable monomer. It is preferably used in a small amount so that the vinyl polymer is dissolved. The weight average molecular weight of the vinyl polymer is 1,000 to
50,000 items are used. If the weight average molecular weight is too small, the toner properties are likely to deteriorate, and if the weight average molecular weight is too large, it becomes difficult to dissolve in the polymerizable monomer.

The vinyl polymer is used in an amount of 5 to 200 parts by weight, preferably 40 to 100 parts by weight, based on 100 parts by weight of the polymerizable monomer. If the amount of the vinyl polymer used is too large, it becomes difficult to dissolve the entire amount in the vinyl monomer, and it becomes difficult to control the particle size. If the amount is too small, the vinyl polymer is dissolved in the polymerizable monomer in advance. The effect becomes smaller.

By dissolving the vinyl polymer in the polymerizable monomer in advance, the molecular weight distribution and the like can be easily adjusted as compared with the case where it is not, so that a toner excellent in offset resistance and fixability can be easily obtained.

Water is mainly used as the aqueous medium used for emulsion dispersion. The ratio of the polymerizable monomer to the aqueous medium is the former /
The latter preferably has a weight ratio of 40/60 to 90/10. If this ratio is too small, it becomes difficult to emulsify and disperse, and if it is too large, the productivity decreases.

As the emulsifier, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant or a nonionic surfactant can be used. Of these, when manufacturing negatively charged toner, an anionic surfactant is used,
When manufacturing a positively chargeable toner, it is preferable to use a cationic surfactant. 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 sulfate salts 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 emulsifier used is 0.01-10% by weight with respect to the polymerizable monomer.
Is preferable, and 0.5 to 5% by weight is particularly preferable.
If the amount of the emulsifier used is too small, stable emulsion polymerization becomes difficult, and if the amount of the emulsifier is too large, the moisture resistance of the resulting toner decreases.

Stabilizers include polyvinyl alcohol, starch,
There are water-soluble polymer substances such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose,
These are preferably used in an amount of 0 to 1% by weight based on the polymerizable monomer.

Examples of the water-soluble polymerization initiator include potassium persulfate,
Persulfate such as ammonium persulfate, hydrogen peroxide, 4,4'-
Azobiscyanovaleric acid, 2,2'-azobis (2-amidinopropane) dihydrochloride, t-butyl hydroperoxide, cumene hydroperoxide and the like can be used. Especially when persulfate is used, the sulfate active anion radical (▲ SO ^- ₄ ▼), which is the initiation active site, is present on the surface of the monomer,
The particles are stabilized by the hydrophilic group of SO ^- ₄ ▼ group and charge,
An emulsion having a relatively uniform particle size is easily obtained.

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

Examples of oil-soluble polymerization initiators include peroxides such as benzoyl peroxide and t-butyl perbenzoate, and azo compounds such as azobisisobutyronitrile and azobisisobutylvaleronitrile. It is preferably used by dissolving it in the body.

The amount of the polymerization initiator used is 0.01 to 10 with respect to the polymerizable monomer.
It is preferably in the range of 0.1 to 5% by weight, preferably 0.1 to 5% by weight.
When the amount of the polymerization initiator is too small, the polymerizable monomer is not completely polymerized and remains in the toner, deteriorating the characteristics of the toner.

Chain transfer agents include alkyl mercaptans such as t-dodecyl mercaptan, lower alkyl santogens such as diisopropyl xanthogen, carbon tetrachloride, carbon tetrabromide, etc., and 0 to 2% by weight based on the polymerizable monomer. It is preferably used.

Examples of the colorant preferably used in the present invention include pigments and dyes. For example, various carbon blacks, nigrosine dyes (CINo.50415), aniline blue (CINo.50405), chalcoil oil blue (CINo.azoec).
Blue 3), Chrome Yellow (CINo.14090), Ultramarine Blue (CINo.77103), Deubon Oil Red (CINo.26105), Orient Oil Red # 330
(CINo.60505), Quinoline Yellow (CINo.4700
5), Methylene Blue Chloride (CINo.52015), Phthalocyanine Blue (CINo.74160), Malachite Green Oxalate (CINo.42000), Lamp Black (CINo.77266), Rose Bengal (CINo.45435),
Oil black, azo oil black, etc. 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 thereof should be about 1 to 30% by weight, preferably 5 to 15% by weight in the toner. Used in various proportions.

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, such as fannes black, channel black, thermal black, acetylene black, lamp black, etc., are particularly preferable for the toner of the present invention. 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 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 content of the grafted carbon black is preferably 50% by weight or less based on the grafted carbon black,
30% by weight or less is preferable. Grafted carbon black is preferable because it has excellent dispersion stability during polymerization, but if the amount of the polymer component is too large, the viscosity tends to be too high when dispersed in the polymerizable monomer. Sex decreases. The amount of grafted carbon black used is
It is preferable to determine by the amount of carbon black component.

The magnetic powder is used when manufacturing a magnetic toner, and can also serve as a coloring agent. Preferred magnetic powders are, 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 having a particle size 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 materials account for 20 to 80% by weight of toner,
Preferably 35 to 70% by weight can be contained. You may use it as a coloring agent in the quantity below this.

Further, a fluidity improver, a cleaning improver, etc. can be used as required. These can be present in the polymerization reaction system and in the product toner,
The product toner is preferably externally added afterwards. These contents are 0 to 3% by weight based on the toner of the present invention.
Is preferred. The fluidity improver includes silane, titanium, aluminum, calcium, magnesium and an oxide of magnesium, or the oxide of which is hydrophobized with a titanium coupling agent or a silane coupling agent. , Metal salts of higher fatty acids such as zinc stearate, lithium stearate and magnesium laurate or aromatic acid esters such as pentaerythritol benzoate.

In the present invention, by selecting the polymerizable monomer and the colorant, it is possible to freely adjust the charge amount and charge polarity of the product toner, but to adjust the charge amount and charge polarity to more desired values. Further, a charge control agent may be used in combination with the colorant in the toner of the present invention.

As the charge control agent preferably used in the present invention, spirone black TRH, spirone black TRH (Hodogaya Chemical Co., Ltd.)
And other azo dyes, p-fluorobenzoic acid, p-nitrobenzoic acid, aromatic acid derivatives such as 2,4-di-t-butylsalicylic acid, and tin compounds such as dibutyl-tin oxide and dioctyl-tin oxide. it can. They are,
It is 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 to coagulate particles containing a colorant and / or magnetic powder. As a result, by appropriately aggregating the polymer particles in the polymerization solution, a toner having an average particle size larger than that of the polymer particles in the polymerization solution and having an incomplete spherical shape and not requiring pulverization is obtained. Suitable particles can be obtained.

Here, it is preferable to adjust the particle size distribution of the agglomerated particles to be 1 to 100 μm, and especially to be 3 to 70 μm. Most preferably, it is adjusted. Average particle size 9 ~
It is preferably adjusted to 15 μm. For the above adjustment, the coagulant should be 0.1% with respect to the weight of the emulsifier in the polymerization liquid.
It is preferable to use 5 to 5 times, preferably 0.3 to 3 times.
If the amount of the coagulant used is too small, the coagulation effect will be insufficient, and if it is too large, the moisture resistance of the toner will be poor and the average particle size of the above particles will be too large.

Since the imperfect spherical toner particles are obtained by this coagulation process, the toner particles have excellent cleaning properties. In addition, since the emulsifier is also removed by this coagulation process, blocking resistance and charge stability are also improved.

In this coagulation step, the polymerization liquid and the coagulant can be mixed by a method of gradually dropping the polymerization liquid into the coagulant aqueous solution with stirring, a method of mixing the coagulant aqueous solution and the polymerization liquid at a constant ratio, or the like. .

In this solidification step, the temperature is not particularly limited, but it is preferably room temperature to 150 ° C, particularly preferably at a temperature above the softening point of the main resin component (along with the heat treatment operation) and below the softening point. When the solidification is carried out at a temperature, it is particularly preferable to heat the salting-out liquid to a temperature above the softening point of the polymer (heat treatment operation). By such a heat treatment operation, the bulk density of the particles of the main resin component is increased, and the moisture resistance, offset resistance, and durability are improved.

A method of adding a large amount of coagulant to the polymerization liquid in the coagulation step to obtain a large coagulated body and pulverizing this to obtain a particle size suitable for the toner can be considered. Thus, the additive can be uniformly dispersed in the resin, but in order to be crushed, it has a shape closer to that of a pulverized toner than the toner of the present invention.
Therefore, the cleaning property and the toner fluidity are poor.

On the other hand, in the present invention, the particles obtained by coagulation can be used as a toner as they are or by simply classifying them, and the shape of the toner particles is not asymmetrical indefinite shape like pulverized toner. In addition, the cleaning property is excellent because it is not a perfect sphere but an incomplete sphere.

Examples of the coagulant include inorganic acids such as hydrochloric acid and sulfuric acid, organic acids such as formic acid and acids, these acids and alkaline earth metals,
There are water-soluble metal salts such as aluminum. These salting-out agents can be used alone or in combination,
Preferred coagulants are magnesium sulphate, aluminum sulphate, barium chloride, magnesium chloride, calcium chloride, sodium chloride and / or their mixtures with inorganic acids. These coagulants are 0.1-1.0 wt% aqueous solution,
Particularly, it is preferably used as an aqueous solution of 0.1 to 5% by weight.

After coagulation, it is subjected to centrifugal dehydration, and further washed, dried and, if necessary, classified to obtain toner particles.

Washing here is preferable in order to completely remove the emulsifier attached to the particles, and this can improve the charging stability and the blocking property together with the coagulation. Washing is preferably performed with warm water at 40 to 60 ° C.

The heat treatment operation after the solidification may be inserted during the cleaning step or between two or more cleaning steps.

Further, in the present invention, the dispersion of the offset inhibitor is added to (a) the polymerization solution during the polymerization until the polymerization rate reaches 90% by weight or more, and (b) after the completion of the polymerization. And / or (c) prior to solidification in the polymerization liquid
It is essential to add after the polymerization liquid after the polymerization is solidified. The dispersion of the anti-offset agent is (a),
It may be added in at least one of the steps (b) and (c), and may be added multiple times.

When the above-mentioned offset inhibitor dispersion is added from the time when the polymerization rate in the polymerization is 90 wt% to the time after the completion of the polymerization and before the solidification, the offset inhibitor does not exist in the core of the polymer particles at the end of the polymerization. Exists in the particles obtained by agglomeration of polymer particles by coagulation and between the polymer particles and the surface of the particles obtained by coagulation, and after the coagulation, a dispersion liquid of an offset inhibitor was added. In this case, the offset inhibitor adheres to the surface of the particles obtained by solidification.

On the other hand, when the polymerization rate of the polymerization is higher than 90% by weight, especially when the dispersion of the offset inhibitor is added at the start of the polymerization, the offset inhibitor is present in the core of the polymer particles at the end of the polymerization. However, even if particles obtained by solidifying the particles are used as toner, the effect of preventing offset is extremely small.

Further, when the offset inhibitor is added after solidification, it is preferable to add it before the heat treatment operation. this is,
It is better to do it before the heat treatment operation than after it.
This is because the anti-offset agent easily adheres sufficiently to the particle surface.

In the present invention, the anti-offset agent dispersion is a liquid in which water is used as a continuous phase and the anti-offset agent is dispersed in the form of fine particles.

Here, as the anti-offset agent, an anti-offset agent which has an anti-offset effect and is dispersible in water is used. For example, various natural waxes such as carnauba wax,
Hardened castor oil, low molecular weight olefin polymers, etc. are used in the present invention, but preferably low molecular weight olefin polymers are used. As the low molecular weight olefin polymer, an olefin polymer or a copolymer of olefin and a monomer other than olefin and having a low molecular weight is used. Here, examples of olefin include ethylene, propylene, butene-1, and the like, and examples of monomers other than olefin include acrylic acid ester and methacrylic acid ester. As such a low molecular weight olefin polymer, for example,
The polyalkylenes described in JP-A No. 55-153944 and the low molecular weight olefin copolymers described in JP-A No. 50-93647 can be used. Further, two or more kinds of the above offset preventing agents may be mixed and 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 referred to in ordinary polymer chemistry, but is generally 1,000 in terms of weight average molecular weight (Mw).
~ 45000, preferably 2000-6000 with a softening point
Those having a temperature of 100 to 180 ° C are preferable, and those having a temperature of 130 to 160 ° C are particularly preferable.

The anti-offset agent in the above dispersion preferably has an average particle size of 5 μm or less and does not include particles having a particle size of more than 20 μm. If the particle size is too large, some toner particles obtained according to the present invention are free of the offset inhibitor.

In the above dispersion, the ratio of the anti-offset agent to the water is preferably 5/5 to 9/1 in terms of weight ratio of the former / the latter. If this ratio is too small, the stability of the dispersion decreases, and if it is too large, the processing efficiency decreases.

There is no particular limitation on the method for producing the above dispersion liquid. For example, a solid or liquid anti-offset agent with a homomixer,
There are a method of dispersing in water by a machine such as a homogenizer, a disperser, an ultrasonic disperser, and a method of dispersing and polymerizing a polymerizable monomer in water. In the former dispersion method, an anionic or nonionic surfactant may be further used in order to improve the stability of the dispersion and to make the particles smaller. The kind and amount of the surfactant vary depending on the offset inhibitor to be dispersed, but the amount is preferably 10% by weight or less based on the offset inhibitor. If the amount of the surfactant is too large, a large amount of the surfactant remains in the toner as the final product, so that the toner becomes hygroscopic and the storage stability and the charging property are adversely affected. Also,
When the resin to be dispersed is solid at room temperature, it is preferable to heat it above the softening point of the resin or add a small amount of an organic solvent to plasticize it.

On the other hand, the latter polymerization method includes an emulsion polymerization method and a suspension polymerization method, but the emulsion polymerization method, which can obtain finer particles, is preferable. The emulsion polymerization method is carried out by emulsifying and polymerizing a polymerizable monomer in an aqueous medium containing an emulsifier. The emulsifier used at this time is preferably 10% by weight or less with respect to the anti-offset agent as in the case of the above-mentioned surfactant. The adverse effects when the emulsifier is too much are the same as in the case of the above surfactant.

In the method of the present invention, the amount of the offset inhibitor dispersion added is not particularly limited, but 0.1 to 30% by weight of the offset inhibitor is contained in the toner. If it is less than 0.1% by weight, the offset preventing effect is not exhibited, and if it exceeds 30% by weight, the image quality including the image strength tends to be remarkably deteriorated. The amount of the dispersion is determined by adjusting the weight of the polymer particles obtained by the polymerization or the amount of the particles obtained by coagulation and the amount of the offset inhibitor to be contained so that the offset inhibitor is in the above range. It is added as a guide.

The toner obtained by the present invention can be used in various development processes,
For example, the cascade developing method described in US Pat. No. 2,618,552, the magnetic brush method described in US Pat. No. 2,874,065, the powder cloud method described in US Pat. No. 2,221,776, US Pat. No. 3,166,432 discloses a touchdown developing method, JP-A-55-18656 discloses a so-called jumping method, and a carrier as a carrier is manufactured by a pulverizing method. Therefore, it can be used in a so-called bipolar magnetic toner method for obtaining a required toner charge.

Further, the toner obtained by the present invention can be used not only in the fixing method by the hot roll method but also in other fixing methods such as the flash method and the oven method. Further, the toner of the present invention can be used in various cleaning methods such as so-called far brush method and blade method.

(Example) Next, the present invention will be described in detail based on examples, but the present invention is not limited thereto. In the examples, "%" means "% by weight" unless otherwise specified. Further, in the following, the weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography using a calibration curve based on standard polystyrene.

Comparative Example 1 (1) Dissolution of polymer In a separable flask 1 equipped with a stirrer, a thermometer and a condenser, 280 g of styrene and 85 g of butyl acrylate.
The mixture was stirred at 180 rpm, and 160 g of a bead-like polymer having a weight average molecular weight of 36,000 and a copolymer composition of styrene / butyl acrylate = 8/2 obtained by suspension polymerization was gradually added to The mixture is kept at 50 ° C for 1 hour to dissolve it and then cooled to room temperature.

(2) Manufacture of emulsion polymerization liquid Next, this polymer solution was put into a 3 l stainless beaker and grafted carbon (grafted carbon GP-E-2,
Ryoyu Kogyo Co., Ltd. 100 g and t-dodecyl mercaptan 0.4 g as a chain transfer agent were added, and mixed and dispersed at 3000 rpm for 30 minutes with a high-speed shear disperser (Tokuki Kika Kogyo TK Homomixer). It was

Next, 1300 g of ion-exchanged water was added to this carbon dispersion, 12 g of sodium dodecylbenzenesulfonate as an anionic surfactant as an emulsifier, and Nonipol PE-68 (Oxypropylene-oxyethylene block manufactured by Sanyo Kasei Co., Ltd.) as a nonionic surfactant. Polymer) 3g, Neugen EA170
(Daiichi Kogyo Seiyaku Co., Ltd. polyoxyethylene glycol nonyl phenyl ether) 3g dissolved in an aqueous solution,
A high-speed shearing disperser (TK Homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.) further emulsified at 3000 rpm for 30 minutes to obtain a black pre-emulsion.

Then, transfer the black pre-emulsion to a 3l 4-neck separable flask equipped with a stirrer, nitrogen inlet, thermometer and condenser, polymerize the flask at 80 ° C for 5 hours under a nitrogen stream, and then cool. , A polymerization solution was obtained. The polymerization rate at this time was 99.5% or more. The molecular weight of the polymer is
Weight average molecular weight (Mw) is 74,000 and number average molecular weight (Mn)
Was 20,000.

(3) Coagulation process / final process 2 l of MgSO ₄ 1% aqueous solution obtained by heating the above-mentioned polymerization liquid 1 to 30 ° C.
While maintaining the temperature of the aqueous solution at 30 ° C with sufficient stirring, the solution was uniformly dropped and solidified in about 30 minutes. For another 30 minutes 10
It was kept warm at 0 ° C 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, it was dried at 30 to 35 ° C. in a dryer to obtain a toner. The particle size of the obtained toner was measured with a Coulter counter, and the particle size was 2 to 50 μm and the average particle size was 14 μm.
It was m. Furthermore, with a differential scanning calorimeter, the glass transition point (T
When g) was measured, it was 73 ° C. This toner is further 5-25μ with a zigzag classifier (100MZR, Alpin)
When classified into m, the yield was 85% of that before the 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.

Example 1 (1) Preparation of anti-offset agent dispersion In a 3 l autoclave, 750 g of low molecular weight polypropylene (Viscor 660P, manufactured by Sanyo Kasei Co., Ltd.), 15 g of sodium dodecylbenzenesulfonate (anionic surfactant) and ion-exchanged water. After adding 2235 g, the container was sealed and heated under pressure to 154 ° C, which is about 20 ° C higher than the melting point of Viscol 660P.
The stirring speed was increased to 1000 rpm and the temperature was kept for 30 minutes. It was cooled while continuing stirring, and the dispersion liquid was taken out.
When the particle size was measured with a Coulter counter, it was found to be a dispersion liquid of particles having an average particle size of 1.2 μ, which were free of particles of 5 μ or more.

(2) Coagulation step / final step Emulsion 1 similar to that used in Comparative Example 1 was mixed with 24 ml of the dispersion prepared in (1). At this time, no particular phenomenon such as cohesive precipitation occurred. Further, while thoroughly stirring the above mixed solution in 2 liters of a 1% aqueous solution of MgSO ₄ heated to 30 ° C., the temperature of the aqueous solution was kept at 30 ° C. and uniformly added dropwise for about 30 minutes for salting out. Furthermore, it was kept at this temperature for 30 minutes and cooled to room temperature.

Next, this slurry was subjected to centrifugal dehydration, washing and drying in the same manner as in Example 1 to obtain a toner. The obtained toner has a particle size of 1 to 50 μm, an average particle size of 14 μm, and a glass transition point (Tg).
Was 73 ° C.

Example 2 Emulsion 1 similar to that used in Comparative Example 1 and 24 ml of an aqueous polyolefin dispersion (Chemipearl W-100, manufactured by Mitsui Petrochemical Industry Co., Ltd.) were mixed, and coagulation similar to Example 1 and final Through the steps, the particle diameter was 1 to 70 μm, the average particle diameter was 14 μm, and the glass transition point (Tg) was 73 ° C. Further, classify, 5 ~
A 25 μm toner was obtained.

Example 3 The same solution as in (1) of Comparative Example 1 was put into a 3 liter stainless beaker and grafted carbon (grafted carbon GP-E was used.
-2, manufactured by Ryoyu Kogyo Co., Ltd.) and t-as a chain transfer agent
Dodecylmethylcaptan 0.4g and azobisisobutyronitrile 7.3g as a polymerization initiator 3000rpm with a homomixer
And mixed and dispersed for 30 minutes.

Next, 1420 g of ion-exchanged water was added to this dispersion as an emulsifying agent, 12 g of sodium dodecylbenzenesulfonate as an anionic surfactant, and nonipol as a nonionic surfactant.
An aqueous solution containing 3 g of PE-68 (oxypropylene-oxyethylene block polymer manufactured by Sanyo Kasei Co., Ltd.) and 3 g of Neuken EA170 (polyoxyethylene glycol nonylphenyl ether) (Daiichi Kogyo Seiyaku Co., Ltd.) was added, and a homomixer was added. The mixture was further emulsified at 3000 rpm for 30 minutes to obtain a black pre-emulsion.

Then, the black pre-emulsion was transferred to a 3 liter four-neck separable flask equipped with a stirrer, a nitrogen inlet, a thermometer and a condenser, and the temperature of the flask was adjusted to 70 under a nitrogen stream.
After polymerizing at 5 ° C for 5 hours, it was cooled to obtain a polymerization solution. The polymerization rate at this time was 99.5%. Further, the molecular weight of the polymer is such that the weight average molecular weight (Mw) is 60,000, and the number average molecular weight (Mw) is
n) was 24,000.

(2) Coagulation step / final step Emulsion 1 produced in this manner and the same coagulation and final steps as in Comparative Example 1 were carried out to obtain a particle diameter of 3 to 120 μm and an average particle diameter of 17
The glass transition temperature (Tg) was 73 ° C. Further classification was carried out to obtain a toner of 5 to 25 μm.

Example 4 (1) Dissolution of polymer In a separable flask of 1 equipped with a stirrer, a thermometer and a condenser, 360 g of styrene and 110 butyl acrylate were used.
After stirring the mixed solution of g at 180 rpm, 50 g of a bead-like polymer having a copolymerization composition of styrene / butyl acrylate = 8/2 and a weight average molecular weight of 36,000 obtained by suspension polymerization was gradually added thereto, The temperature is kept at 50 ° C for 1 hour to dissolve it, and then it is cooled to room temperature.

(2) Production of Emulsion Polymerization Liquid This polymer solution was placed in a 3 l stainless beaker and emulsified and polymerized in the same manner as in Comparative Example 1 to obtain an emulsion liquid.

(3) Coagulation step / final step The emulsion thus obtained was subjected to the same coagulation step and final step as (3) of Comparative Example 1 to obtain a particle size of 1 to 50 μm, an average particle size of 14 μm, and a glass transition point. (Tg) was 73 ° C. Further classification was carried out to obtain a toner of 5 to 25 μm.

Comparative Example 2 (1) Production of Emulsion Polymerization Liquid 100 g of grafted carbon (graft carbon GP-E-2, manufactured by Ryoyu Kogyo Co., Ltd.) in a 3 l stainless beaker, 400 g of styrene as a polymerizable monomer, and acrylic acid 120 g of butyl and 0.6 g of t-dodecyl mercaptan as a chain transfer agent,
It was mixed and dispersed with a homomixer at 3000 rpm for 30 minutes.

Next, in this carbon dispersion, 1420 g of ion-exchanged water was used as an emulsifier, 12 g of sodium dodecylbenzenesulfonate which was an anionic surfactant, and Nonipol PE-68 which was a nonionic surfactant (Oxypropylene-oxyethylene manufactured by Sanyo Kasei Co., Ltd.). Block polymer) 3g, Neugen EA1
An aqueous solution containing 3 g of 70 (polyoxyethylene glycol nonyl ether manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 12 g of ammonium persulfate as a polymerization initiator was added, and the mixture was further emulsified with a homomixer at 3000 rpm for 30 minutes to obtain a black pre-emulsion.

Then, the black pre-emulsion was transferred to a 3 liter four-neck separable flask equipped with a stirrer, a nitrogen inlet, a thermometer and a condenser, and the temperature of the flask was adjusted to 70 under a nitrogen stream.
After polymerizing at 5 ° C. for 5 hours, it was cooled to obtain an emulsion polymerization liquid.
The polymerization rate at this time was 99.5%. As for the molecular weight of the polymer, the weight average molecular weight (Mw) was 86,000 and the number average molecular weight (Mn) was 30,000.

(2) Coagulation Step / Final Step The emulsion polymerization liquid thus obtained was used in Comparative Example 1 (3).
The same solidification step, final step, and classification were performed to obtain toner.

Comparative Example 3 The emulsion polymerization liquid prepared in (1) of Comparative Example 2 was solidified by adding an offset inhibitor in the same manner as in Example 2, and the same final step and classification were carried out to obtain a toner.

Using the toners obtained in Examples 1 to 4 and Comparative Examples 1 to 3, electrophotographic toner characteristics were tested using a plain paper copying machine (SFT-802, Sanyo Electric Co., Ltd.). However, hydrophobic silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) and zinc stearate were externally added to the above toners as a fluidity improver by 0.6% and 0.1%, respectively.
The test results are shown in Table 1.

The evaluation of the electrophotographic characteristics in the above Examples and Comparative Examples was carried out as follows.

(A) Resolution: Electrophotographic Society Test Chart No. 1 was used to make copies on plain paper using each of the developers prepared. The copied image can be read in detail, but comparative evaluation was performed.

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

Gradation: Similar to the resolution, 11 in the center of the test chart
The evaluation was performed using the shaded parts divided into stages.

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

(D) Blotting property: 50 toners were prepared for each.
The toner was allowed to stand for 72 hours at a temperature of 95 ° C and a humidity of 95%, and it was determined whether the toner had blocked. ◯: Excellent x: Inferior.

(E) Charge stability: Each of the prepared developers was stirred by a copying machine, the charge amount was measured at regular intervals, and judged by the change in the charge amount. Good: Excellent x: Poor

(F) Durability: 10,000 copies were continuously made under the conditions of a temperature of 30 ° C. and a humidity of 80% RH using a copying machine for each of the prepared developers. The scattering of the toner generated at this time was examined and judged by the following evaluation.

⊚: No toner scattering ○: Toner scattering was slightly observed Δ: Toner scattering was large ×: Toner scattering was large (g) Hygroscopicity: Each toner was 25 ° C and humidity 98
It is allowed to stand for 24 hours under the condition of ° C, and the ratio of the weight increase after humidification to the weight before humidification is shown in%.

(H) Offset resistance: plain paper copier (Sanyo Electric Co., Ltd.)
SFT-802) removes the fixing part and obtains an unfixed toner image. The upper part is composed of a Teflon coated roll and the lower part is a silicone rubber coated roll. Fixing was performed at a speed of 70 mm / sec and a pressure between rolls of 0.5 kg ^f / cm, and those that were not offset were evaluated as ◯, and those that were offset were evaluated as x.

(I) Fixing rate: Fix at 140 ° C in the same manner as the offset resistance, and erase the solid black part (Lion Co., Ltd. SF-12).
Rubbing was performed 10 times in 0), and the retention rate of the image density after rubbing is shown in%.

(Effect of the Invention) According to the present invention, the resolution, the image density, the gradation, the cleaning property, the charging stability, and the blocking property are excellent, and the fixing property is excellent when the fixing is performed by the heat roll method, and the offset development is not exhibited. An electrophotographic toner suitable for development can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyuki Iguchi 4-13-1, Higashimachi, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Factory (72) Inventor Hideki Kajiwara, 4-13, Higashimachi, Ibaraki Prefecture No. 1 Hitachi Chemical Co., Ltd. Yamazaki Plant (56) Reference JP-A-58-50544 (JP, A) JP-A-56-98202 (JP, A) JP-A-59-123852 (JP, A) Special Kai 57-211157 (JP, A) JP 57-154253 (JP, A)

Claims (5)

[Claims] 1. A vinyl polymer having a weight average molecular weight of 1,000 to 50,000 is dissolved in 100 parts by weight of a polymerizable monomer and then emulsified and dispersed in the presence of a colorant and / or magnetic powder. , A main resin component is polymerized, and a coagulant is added to the obtained polymerization liquid to coagulate so that the particles in the polymerization liquid have a particle size suitable for a toner, and a dispersion liquid of an offset inhibitor. Is added during the polymerization until the polymerization rate is 90% by weight or more until the completion of the polymerization, at the time after the completion of the polymerization and before the coagulation and / or after the coagulation and before the dehydration so that the toner contains an offset inhibitor. A method for producing an electrophotographic toner, comprising: 2. The method for producing an electrophotographic toner according to claim 1, wherein the coagulant is used in the coagulation in an amount of 0.1 to 5 times the weight of the emulsifier in the polymerization liquid. 3. The 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 coagulating agent. Manufacturing method. 4. The electron according to claim 1, 2, or 3, characterized in that, upon solidification, the obtained polymerization liquid is heated to a temperature not lower than the glass transition point of the main resin component. Method for producing photographic toner. 5. The electrophotographic use according to claim 1, 2, 3 or 4, wherein an oil-soluble polymerization initiator and a water-soluble polymerization initiator are used together as a polymerization initiator during polymerization. Toner manufacturing method.