JP2003215841A - Method for manufacturing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a toner by which the electrification property of a toner in each production lot can be kept constant, the image characteristics at normal temperature and normal humidity are improved, and the image characteristics under high temperature and high humidity conditions are significantly stabilized. <P>SOLUTION: The method for manufacturing a toner includes: a polymerization process to polymerize a polymerizable monomer composition containing at least polymerizable monomers and a coloring agent in an aqueous medium containing a dispersion stabilizer to obtain color particles; a cleaning process to clean the color particles with an aqueous medium; and a drying process to dry the dehydrated color particles. In the cleaning process, the electric conductivity A (μS/cm) of the aqueous medium used in the finish cleaning and the electric conductivity B (μS/cm) of the liquid separated from the color particles by dehydration after the finish cleaning are controlled to satisfy the relation expressed by (1): 10≤A≤500, (2): 10≤B≤500 and (3): 0.5≤A/B≤1.5. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner used for electrophotography, electrostatic recording, electrostatic printing, etc.
More specifically, the present invention relates to a method for producing a toner having no variation in charging property.

[0002]

2. Description of the Related Art In electrophotography and the like, as a toner for visualizing (developing) an electrostatic image, a coloring agent such as carbon black and other characteristic imparting agents are dispersed in a binder resin such as a thermoplastic resin. Granulated compositions are widely used.

Conventionally, as a method for producing a toner, a coloring agent, a charge control agent and the like are added to a thermoplastic resin, premixed by a mixer, and then melt-kneaded in a heating kneader to obtain a coloring agent and the like in the resin. There is known a pulverization method in which the powder is dispersed, cooled, coarsely pulverized and finely pulverized, and then classified so as to obtain a desired particle size. However, this pulverization method has a complicated manufacturing process and may have non-uniform electric or magnetic properties, so that satisfactory characteristics may not be obtained. As an alternative method, a method for producing a toner by a polymerization method is proposed. Has been done.

In the polymerization method, a colorant and other property-imparting agents are added to the polymerizable monomer and uniformly dispersed to prepare a polymerizable monomer composition, and the polymerizable monomer composition is By adding and polymerizing in an aqueous medium containing a dispersion stabilizer,
A toner is obtained by forming colored particles containing a colorant and then washing and drying the colored particles.

This polymerization method includes emulsion polymerization, suspension polymerization, precipitation polymerization, soap-free polymerization and the like. However, since the colorant can be uniformly contained, the charging property and the transfer property can be improved. Suspension polymerization is commonly used. In this suspension polymerization, in order to obtain fine colored particles having a uniform particle size distribution, in addition to uniformly dispersing a colorant and the like in the monomer, droplets of the polymerizable monomer composition It is important to uniformly and stably suspend the in the aqueous medium.

Conventionally, various dispersion stabilizers have been added to suspension polymerization systems in order to uniformly and stably disperse the droplets of the polymerizable monomer composition. Of these dispersion stabilizers, poorly water-soluble metal compounds such as calcium phosphate give colored polymer particles having a sharp particle size distribution, and are therefore used alone or in combination with other additives ( JP-A-63-198075 and JP-A-4-12
No. 7162). After completion of the suspension polymerization, in order to remove the poorly water-soluble metal compound used as the dispersion stabilizer, an acid is added for washing (acid washing), and then, after sufficiently washing with water, filtration, decantation, The toner is obtained by dehydrating by a suitable method such as centrifugation to collect the colored particles and drying.

The toner thus obtained can obtain good image characteristics under normal temperature and normal humidity, but under high temperature and high humidity, a stable image such as low image density and fog or unevenness is not necessarily obtained. There was a problem that I could not get it.
The Applicant has found that these problems are related to the content of the metal ion remaining in the toner, and the metal ion derived from the sparingly water-soluble metal compound which is the dispersion stabilizer is 1
It has been proposed that by setting the content to 000 ppm or less, the obtained toner can provide a stable image even under high temperature and high humidity (JP-A-8-160661).

[0008]

By carrying out a washing step after polymerization, the residual metal ion content is reduced to 1,000 ppm.
Although it is possible to make the following, the characteristics such as the average particle size and particle size distribution of the toner may differ subtly for each polymerization.Therefore, even after the same washing process, residual metal ions may remain between production lots. The amount will not be the same. for that reason,
In some cases, the amount of toner charge varies between product lots. After washing with water having a total content of metal cations of less than 5 mg / liter in the washing step and the total content of metal cations derived from the dispersion stabilizer in the washing wastewater has become less than 5 mg / liter, Na ⁺ , K ^A method for producing a toner has been proposed in which water having a total content of ⁺ , Mg ^2+, and Ca ²⁺ of 10 to 150 mg / liter is poured, dehydrated, and the obtained wet colored polymer particles are dried (Japanese Patent Laid-Open No. 2001-2001). -265059
Issue). However, this method is aimed at controlling the state of existence of a decomposition product derived from a metal complex of an alkylsalicylic acid, which is a charge control agent, or a solution of other additives in water on the toner surface after drying. However, it was found that a toner having a stable charge amount between production lots cannot be obtained.

Therefore, the object of the present invention is to make it possible to keep the chargeability of the toner constant for each production lot, and to improve the image characteristics, especially the image characteristics under high temperature and high humidity and low temperature and low humidity. Another object of the present invention is to provide a method for producing a stabilized toner. As a result of detailed examination of the washing process with water in which the total content of Na ⁺ , K ⁺ , Mg ²⁺ and Ca ²⁺ is adjusted, the present inventors have found that the amount of charge of the toner is also increased by ions other than the ions of the above four elements. And by adjusting the electrical conductivity of the aqueous medium used in the final wash and the electrical conductivity of the separation liquid obtained in the subsequent dehydration, rather than the specific metal ion content as described above. The inventors have found that a toner having a stable charge amount can be obtained, and have completed the present invention based on this finding.

[0010]

Thus, according to the present invention, (1) a polymerizable monomer composition containing at least a polymerizable monomer and a colorant is added to an aqueous medium containing a dispersion stabilizer. A method for producing a toner, comprising a polymerization step of polymerizing to obtain colored particles, a washing step of washing / dehydrating the colored particles with an aqueous medium, and a drying step of drying the colored particles, wherein a final washing step is carried out in the washing step. The electric conductivity A (μS / cm) of the aqueous medium used in step A and the electric conductivity B (μS / cm) of the separated liquid separated from the colored particles by dehydration after the final washing.
Is a method for producing a toner satisfying the following relational expressions (1), (2) and (3): 10 ≦ A ≦ 500 (1) 10 ≦ B ≦ 500 (2) 0.5 ≦ A / B ≦ 1. 5 (3) is provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing a toner according to the present invention comprises polymerizing a polymerizable monomer composition containing at least a polymerizable monomer and a colorant in an aqueous medium containing a dispersion stabilizer. Having a polymerization step of obtaining colored particles by washing, a washing step of washing and dehydrating the colored particles with an aqueous medium, and a drying step of drying the colored particles, in which the electrical conductivity A of the aqueous medium used in the final washing is (ΜS / cm) and the electrical conductivity B of the separated liquid separated from the colored particles by dehydration after the final washing.
(ΜS / cm) is characterized by satisfying the following relational expressions (1), (2) and (3). 10 ≦ A ≦ 500 (1) 10 ≦ B ≦ 500 (2) 0.5 ≦ A / B ≦ 1.5 (3)

When colored particles are obtained in the polymerization step, conventional suspension polymerization or emulsion polymerization can be employed. In the suspension polymerization method, a colorant and other additives are added to the polymerizable monomer and mixed with stirring to prepare a polymerizable monomer composition.
This polymerizable monomer composition was added to an aqueous dispersion medium to which a dispersion stabilizer was added, and stirred so that the dispersed droplets of the polymerizable monomer composition were in the desired particle size range. , Suspend. Then, in the presence of a polymerization initiator, the mixture is heated to a predetermined temperature and polymerized with stirring.

In the emulsion polymerization method, for example, a polymerizable monomer composition containing a polymerizable monomer and a wax is emulsified with an anionic surfactant and then polymerized to obtain a dispersion liquid of polymer particles. To get On the other hand, the colorant is emulsified with an anionic surfactant to obtain a dispersion of colorant particles. Mix the two dispersions, make the pH alkaline with a base, add a nonionic surfactant as a dispersion stabilizer, and then add an alkali metal salt or alkaline earth metal salt as a flocculant. And a method of obtaining colored particles by associating the particles contained in the dispersion liquid. In the method of obtaining colored particles by the emulsion polymerization method, there are many combinations by changing the additive contained in the dispersion liquid of the two particles to be associated. Further, by heating the colored particles obtained by the association to a temperature not lower than the glass transition point of the colored particles, salting out can be promoted and at the same time fusion can be performed. Among the above-mentioned polymerization methods, the suspension polymerization method is preferable from the viewpoint of easily controlling the chargeability of the obtained toner. The polymerization temperature is usually 50 to 100 ° C, preferably 60 to 95 ° C.

As the polymerizable monomer that can be used in the method for producing the toner of the present invention, a monovinyl monomer, a crosslinkable monomer,
A macromonomer etc. can be mentioned. Examples of monovinyl monomers include aromatic vinyl monomers such as styrene, vinyltoluene, and α-methylstyrene; (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid. Propyl, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
(Meth) acrylic such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and (meth) acrylamide. Acid derivatives; monoolefin monomers such as ethylene, propylene and butylene; and the like. The monovinyl monomer may be used alone or in combination of a plurality of monomers. Of these monovinyl monomers, an aromatic vinyl monomer alone, a combination of an aromatic vinyl monomer and a (meth) acrylic acid derivative, and the like are preferably used.

The use of a crosslinkable monomer or a crosslinkable polymer together with the monovinyl monomer is effective for improving hot offset. The crosslinkable monomer is a monomer having two or more polymerizable carbon-carbon unsaturated double bonds. In particular,
Aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and their derivatives; Diethylenically unsaturated carboxylic acid esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate;
Examples thereof include compounds having two vinyl groups such as N, N-divinylaniline and divinyl ether, and compounds having three or more vinyl groups such as pentaerythritol triallyl ether and trimethylolpropane triacrylate. The crosslinkable polymer is a polymer having two or more vinyl groups in the polymer, and specifically, such as polyethylene, polypropylene, polyester and polyethylene glycol having two or more hydroxyl groups in the molecule. An ester obtained by subjecting a polymer and an unsaturated carboxylic acid monomer such as acrylic acid or methacrylic acid to a condensation reaction can be mentioned. These crosslinkable monomers and crosslinkable polymers may be used alone or in combination of two or more. The amount used is usually 10 parts by weight or less, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the monovinyl monomer.

Further, it is preferable to use a macromonomer together with the monovinyl monomer because a good balance between storability and low temperature fixability can be obtained. The macromonomer has a vinyl polymerizable functional group at the end of the molecular chain, and is an oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000. When a polymer having a small number average molecular weight is used, the surface portion of the polymer particles becomes soft and the storage stability is deteriorated. On the other hand, when a polymer having a large number average molecular weight is used, the meltability of the macromonomer deteriorates and the fixability deteriorates. Examples of the vinyl polymerizable functional group at the end of the macromonomer molecular chain include an acryloyl group and a methacryloyl group, and a methacryloyl group is preferable from the viewpoint of ease of copolymerization.

The macromonomer preferably has a glass transition temperature higher than the glass transition temperature of the polymer obtained by polymerizing the monovinyl monomer. Specific examples of the macromonomer used in the present invention include a polymer obtained by polymerizing styrene, a styrene derivative, a methacrylic acid ester, an acrylic acid ester, acrylonitrile, methacrylonitrile or the like, or a polysiloxane skeleton. Among them, hydrophilic monomers, particularly polymers obtained by polymerizing methacrylic acid esters or acrylic acid esters alone or in combination thereof are preferable.
When a macromonomer is used, the amount thereof is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, and more preferably 0.05 to 100 parts by weight of the monovinyl monomer. ~ 1 part by weight. If this amount is too small, the effect of using the macromonomer may not be exhibited, and conversely if the amount is extremely large, the fixability may be deteriorated.

As the colorant, carbon black, titanium black, magnetic powder, oil black, titanium white, or any pigment and / or dye can be used. Black carbon black has a primary particle size of 20-
Those having a thickness of 40 nm are preferably used. If it is smaller than 20 nm, the carbon black may aggregate and may not be uniformly dispersed in the toner, resulting in a toner with a lot of fog. On the other hand, if it is larger than 40 nm, a large amount of polycyclic aromatic hydrocarbon compound such as benzpyrene produced during the production of carbon black may remain in the toner.

To obtain a full color toner, yellow colorants, magenta colorants and cyan colorants are usually used. As the yellow colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17,
62, 65, 73, 83, 90, 93, 97, 120,
138, 155, 180, 181, 185 and 186
Etc. As the magenta colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Red 48, 57, 58, 60,
63, 64, 68, 81, 83, 87, 88, 89, 9
0, 112, 114, 122, 123, 144, 14
6, 149, 163, 170, 184, 185, 18
7, 202, 206, 207, 209, 251, C.I.
I. Pigment Violet 19 and the like. As the cyan colorant, a copper phthalocyanine compound and its derivative, an anthraquinone compound, etc. can be used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 1
5: 1, 15: 2, 15: 3, 15: 4, 16, 17,
And 60 and the like. The amount of such a colorant is usually 1 to 10 parts by weight based on 100 parts by weight of the polymerizable monomer.

In addition to the above-mentioned polymerizable monomer and colorant, a charge control agent, a release agent, a magnetic material and the like can be added to the polymerizable monomer composition. As the charge control agent, a charge control agent conventionally used for toner can be used. For example, Bontron N01 (manufactured by Orient Chemical Industry Co., Ltd.), Nigrosine Base EX (manufactured by Orient Chemical Industry Co., Ltd.), Spiron Black TRH (manufactured by Hodogaya Chemical Co., Ltd.), T-77 (manufactured by Hodogaya Chemical Co., Ltd.), Bontron S-34. (Manufactured by Orient Chemical Industry Co., Ltd.), Bontron E-
81 (Orient Chemical Co., Ltd.), Bontron E-84
(Made by Orient Chemical Industry), COPY CHARGE
NX (Clariant), COPY CHARGE
Charge control agents such as NEG (manufactured by Clariant Co., Ltd.) may be mentioned, and JP-A No. 63-60458 and JP-A No. 3-6043.
-175456, JP-A-3-243954, JP-A-11-15192, etc., a quaternary ammonium (salt) group-containing copolymer produced according to the description, JP-A-1-217464, The sulfonic acid (salt) group-containing copolymer produced according to the description of Kaihei 3-15858 can be used as a charge control agent (hereinafter, referred to as "charge control resin").

Among these, it is preferable to use the charge control resin. The charge control resin is preferable because it has high compatibility with the binder resin, is colorless, and can provide a toner having stable chargeability even in continuous color printing at high speed. The glass transition temperature of the charge control resin is usually 40-80.
C, preferably 45 to 75 ° C., more preferably 45 to 75 ° C.
It is 70 ° C. If it is lower than this range, the storage stability of the toner deteriorates, and conversely if it is higher, the fixing property may deteriorate. The amount of the charge control agent is usually 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer.

Examples of the releasing agent include low molecular weight polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; plant-based natural waxes such as candelilla, carnauba, rice, and wax; paraffin, microcrystalline, Petroleum waxes such as petrolactam; synthetic waxes such as Fischer-Tropsch wax; and polyfunctional ester compounds such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, and dipentaerythritol hexamyristate. These can be used alone or in combination of two or more.

Of these, synthetic wax (particularly Fischer-Tropsch wax), petroleum wax, polyfunctional ester compound and the like are preferable. Among the polyfunctional ester compounds, in the DSC curve measured by a differential scanning calorimeter, the endothermic peak temperature at the time of temperature rise is 30 to 120 ° C,
Preferably 40 to 100 ° C., more preferably 50 to 80
A polyvalent ester compound such as a pentaerythritol ester having a temperature range of 50 ° C. or a dipentaerythritol ester having an endothermic peak temperature of 50 to 80 ° C. is particularly preferable in terms of fixing-releasing balance as a toner,
Among them, styrene 1 has a molecular weight of 1000 or more.
It is more preferable to dissolve 5 parts by weight or more at 25 ° C. with respect to 00 parts by weight and to have an acid value of 10 mg / KOH or less, since a remarkable effect in lowering the fixing temperature is exhibited. Endothermic peak temperature is AST
It is the value measured by MD3418-82. The amount of the release agent is 100 parts by weight of the polymerizable monomer,
Usually, 0.5 to 50 parts by weight, preferably 1 to 20 parts by weight is used.

Examples of the magnetic material include iron oxides such as magnetite, γ-iron oxide and ferrite; metals such as iron, cobalt and nickel.

Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide. Compounds; and metal compounds such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; and the like. These dispersion stabilizers may be used alone or in combination of two or more kinds. Among these, a dispersion stabilizer containing a metal compound, particularly a colloid of a sparingly water-soluble metal hydroxide, can narrow the particle size distribution of the polymer particles, the residual amount after washing is small, and the image It is preferable because it can be reproduced clearly.

The dispersion stabilizer containing a colloid of a poorly water-soluble metal hydroxide is not limited by its production method, but it is obtained by adjusting the pH of the aqueous solution of the water-soluble polyvalent metal compound to 7 or more. Metal hydroxide colloid,
Particularly, it is preferable to use a colloid of a poorly water-soluble metal hydroxide, which is produced by the reaction of the water-soluble polyvalent metal compound and the alkali metal hydroxide in the aqueous phase.

In the number particle size distribution of the slightly water-soluble metal hydroxide colloid, the cumulative particle number Dp50 calculated from the small particle size side is 50%, and the particle size Dp50 is 0.5 μm or less, and 90
It is preferable that the particle diameter Dp90, which is%, is 1 μm or less. If the particle size of the colloid becomes large, the stability of polymerization is impaired and the storage stability of the toner is deteriorated.

The dispersion stabilizer is usually used in a proportion of 0.1 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer. If this ratio is less than 0.1 part by weight, it is difficult to obtain sufficient polymerization stability, and polymer aggregates are easily generated. On the other hand, if it exceeds 20 parts by weight, the toner particle size after polymerization becomes too fine, which is not practical.

As the polymerization initiator, a persulfate such as potassium persulfate; 4,4′-azobis (4-cyanovaleric acid),
2,2'-azobis (2-methyl-N- (2-hydroxyethyl) propionamide, 2,2'-azobis (2
-Amidinopropane) dihydrochloride, 2,2'-
Azobis (2,4-dimethylvaleronitrile), 2,
Azo compounds such as 2'-azobisisobutyronitrile; lauroyl peroxide, benzoyl peroxide, t-
Butyl peroxy-2-ethyl hexanoate, t-hexyl peroxy-2-ethyl hexanoate, t-butyl peroxypivalate, di-isopropyl peroxydicarbonate, 1,1,3,3-tetramethyl Examples thereof include peroxides such as butylperoxy-2-ethylhexanoate and t-butylperoxyisobutyrate.

Among these, it is particularly preferable to select an oil-soluble polymerization initiator that is soluble in the polymerizable monomer used, and a water-soluble polymerization initiator can be used in combination therewith if necessary. . The polymerization initiator is a polymerizable monomer 10
0.1 to 20 parts by weight, preferably 0.3 to 15 parts by weight, and more preferably 0.5 to 10 parts by weight, relative to 0 parts by weight. The polymerization initiator may be added in advance to the polymerizable monomer composition, but in the case of suspension polymerization, a suspension after the granulation step or in the middle of the polymerization reaction, in the case of emulsion polymerization the emulsification step After the completion of the polymerization or during the polymerization reaction, the emulsion may be directly added.

Further, it is preferable to add a molecular weight modifier during the polymerization. As the molecular weight modifier, for example,
t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, 2,2,4,6,6-
Mention may be made of mercaptans such as pentamethylheptane-4-thiol. These molecular weight modifiers can be added before the start of the polymerization or during the polymerization.
The molecular weight modifier is 100 parts by weight of the polymerizable monomer,
Usually, it is used in a proportion of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight.

The aqueous dispersion of colored particles obtained in the polymerization step is subsequently sent to the washing step. The washing step includes washing to remove impurities such as a dispersion stabilizer used to disperse the particles from the particles and dehydration to separate the colored particles from the aqueous medium. When colored particles are obtained by an emulsion polymerization method, it is desirable to remove dehydration and washing with an aqueous medium repeatedly to remove the aggregating agent composed of an alkali metal salt or an alkaline earth metal salt. When colored particles are obtained by the suspension polymerization method, particularly when a poorly water-soluble metal compound is used as a dispersion stabilizer, an acid or an alkali is added to the aqueous medium containing the colored particles after polymerization to make the poorly water-soluble compound. It is desirable that after the soluble metal compound is solubilized in an aqueous medium and removed from the colored particles, washing with an aqueous medium is further repeated. At this time, in order to solubilize the poorly water-soluble metal compound in an aqueous medium, an acid such as hydrochloric acid or sulfuric acid or an alkali such as sodium hydroxide is appropriately selected and used according to the kind of the poorly water-soluble metal compound. For example, when magnesium hydroxide is used as the poorly water-soluble metal compound,
Sulfuric acid is added to acidify the pH of the system and magnesium hydroxide is changed to magnesium sulfate to solubilize it in water.

In the toner manufacturing method of the present invention, in the washing step, the electric conductivity A of the aqueous medium used in the final washing is
(ΜS / cm) and the electrical conductivity B (μS / cm) of the separated liquid separated from the colored particles by dehydration after the final washing must satisfy the following relational expressions (1), (2) and (3). There is. 10 ≦ A ≦ 500 (1) 10 ≦ B ≦ 500 (2) 0.5 ≦ A / B ≦ 1.5 (3) The electric conductivity A of the aqueous medium used in the final washing is 20 to 20.
300 μS / cm is preferable, 30 to 200 μS / cm
Is more preferable. The electrical conductivity of the separated liquid separated from the colored particles by dehydration after the final washing is 20 to 300 μS.
/ Cm is preferable, and 30 to 200 μS / cm is more preferable. Moreover, the ratio A / B of these electric conductivities is 0.6.
Is preferably 1.2 to 1.2, more preferably 0.7 to 1.1.

In producing the same type of toner, the target value of the electric conductivity B of the separated liquid separated from the colored particles by the dehydration after the final washing is arbitrarily set depending on the kind. However, when the electric conductivity B of the separated liquid separated from the colored particles by the dehydration after the final washing is less than 10 μS / cm, the toner charge amount becomes large, and paper stains may occur in a low temperature and low humidity environment. 500 μS / cm
If it is larger than the above range, the toner charge amount becomes small and fog may occur in a high temperature and high humidity environment. If the electric conductivity A of the aqueous medium used in the final washing is less than 10 μS / cm, the electric conductivity B of the separated liquid separated from the colored particles by the dehydration after the final washing cannot be made a constant value. ,as a result,
The toner charge amount becomes unstable. Conversely, 500 μS / c
If it is larger than m, the electric conductivity B of the separated liquid separated from the colored particles cannot be kept within the above range due to dehydration after the final washing, and as a result, the charge amount of the toner becomes small and the toner cannot be charged under high temperature and high humidity environment. Fog may occur. Further, if A / B is smaller than 0.5, the electric conductivity B of the separated liquid separated from the colored particles cannot be made to be a constant value by the dehydration after the final washing, and as a result, the charge amount of the toner becomes small. It becomes unstable. On the other hand, when it is larger than 1.5, the electric conductivity B of the separated liquid separated from the colored particles by the dehydration after the final washing cannot be made within the above range, and as a result, the charge amount of the toner becomes small and the high temperature becomes high. Fog may occur in a high humidity environment.

Usually, in the washing step, after the polymerization step,
Washing and dehydration are usually repeated in order to remove unnecessary substances such as a dispersion stabilizer from the aqueous medium containing the colored particles. Electrical conductivity of 10 in a series of washing steps
After washing with an aqueous medium of μS / cm or less, the electrical conductivity of the separated liquid separated from the colored particles by dehydration after the final washing is
After setting the electric conductivity to a desired value or less, the electric conductivity is 10 to 50.
Method of washing with 0 μS / cm, electric conductivity 10-500
Examples thereof include a method of repeatedly washing with an aqueous medium of μS / cm. By adopting these methods, there is no variation in the chargeability of the obtained toner, and stable toner production is possible. In this washing step, it is preferable to use an aqueous medium containing a polyvalent metal ion because the chargeability of the toner will be stable. It is more preferable that the polyvalent metal ion is magnesium ion.

In the present invention, the dehydration in the washing step is carried out by any one of the vacuum filtration method, the pressure filtration method and the centrifugal separation method.
Or, combine them. As a device that can be used for these filtration methods, a continuous belt filter in the vacuum filtration method, a filter press in the pressure filtration method,
Examples of the centrifugal separation method include a siphon peeler type centrifuge that uses a filter medium and a decanter type centrifugal separator that does not use a filter medium in the centrifugal separation method. These devices can be used alone or in combination of both.

The continuous belt filter has a structure in which a filter cloth is arranged on a drain screw belt, and a vacuum pan is installed below the drain screw belt via a slide plate having excellent wear resistance. There is. The slurry is
It is supplied onto the filter cloth from the upper part of the filtration surface and filtered by vacuum action. The filtrate is collected in a vacuum pan and sent to the vacuum tank through the filtrate tube. The filtered cake and the filter cloth run together with the drain screw belt, and the cleaning water is sprayed from the upper part between them so that the soluble substances in the cake are discharged together with the filtrate. The dehydrated cake is peeled off from the filter cloth by the discharge roll. An example of such a continuous belt filter is an Eagle filter manufactured by Sumitomo Heavy Industries, Ltd.

The filter press is characterized in that filtration by pressure and dewatering by pressing can be continuously performed, and dewatering and washing steps can be continuously performed by flowing washing water to the dehydrated cake. An example of such a filter press is the NR-PF-BL type manufactured by Noritake Iron Works.

The siphon peeler type centrifuge is
It is a centrifugal filter equipped with a siphon mechanism and has a structure in which vacuum filtration is added to conventional centrifugal filtration. That is, the siphon peeler type centrifuge is characterized in that a vacuum is generated under the filter cloth by sucking the filtrate with a siphon tube, and the vacuum filtration pressure is simultaneously used in addition to the centrifugal filtration pressure. In addition, since the siphon peeler type centrifuge can control the filtration rate of the cleaning liquid and hold cleaning, the removal efficiency of impurities in the solid content is high. As such a siphon peeler type centrifuge, there is a siphon peeler centrifuge HZ-Si manufactured by Mitsubishi Kakoki. The decanter type centrifuge is a centrifuge that discharges the separated liquid from the small diameter side of the inclined wall by rotating an outer cylinder equipped with the inclined wall at high speed. The feature is that it does not need to be clogged or replaced. As such a decanter type centrifugal separator, there is a High-G decanter manufactured by Tomoe Kogyo Co., Ltd.

In the method of the present invention, the residual concentration of metal ions can be efficiently reduced to 1,000 ppm or less by repeatedly performing dehydration and washing with water using such a filtration device. In addition, the residual metal ion concentration can be further reduced by using a continuous belt filter and a siphon peeler type centrifuge or a filter press together.

The colored particles dehydrated by the washing step are
Then, it is sent to the drying process. The drying step is a step of removing water that cannot be removed only by dehydration. If the amount of water in the colored particles increases, the amount of charge of the toner may not reach the required amount of charge, which may lead to deterioration in image quality. Therefore, it is desirable that the amount of water in the toner be as small as possible. Examples of the dryer used in the drying step include a spray dryer, a fluidized dryer, a tray-type warm air dryer, a vacuum dryer, and the like, but when reducing water adhering to the colored particles, the colored particles are used. When heated, the colored particles agglomerate and the image quality is deteriorated. Therefore, a vacuum dryer capable of drying at a relatively low temperature is preferable. The vacuum dryer is preferably one capable of agitating the colored particles in the apparatus. As such a dryer, an SV mixer manufactured by Shinko Pantec Co., particularly an SV mixer is used.
Examples include T series such as -001VT and conical blender dryer manufactured by Nippon Dryer Co., Ltd.

The volume average particle diameter (dv) of the toner obtained by the production method of the present invention is usually 2 to 10 μm, preferably 2 to 9 μm, more preferably 3 to 8 μm.
The volume average particle diameter (dv) / number average particle diameter (dp) is usually 1.7 or less, preferably 1.5 or less, more preferably 1.3 or less. The circularity measured by the flow-type particle analyzer is usually 0.90 or more, preferably 0.95 or more. The amount of residual metal ions derived from the dispersion stabilizer contained in the toner is usually 1,000 ppm or less,
Preferably 500 ppm or less, more preferably 300 p
It is pm or less.

If necessary, the toner produced by the method of the present invention may be mixed with an external additive to obtain a developer. Examples of the external additive include inorganic particles and organic resin particles. These particles added as an external additive have a smaller average particle size than the colored particles. For example, the inorganic particles include silicon dioxide, aluminum oxide, titanium oxide, zinc oxide, tin oxide, barium titanate, strontium titanate, and the like, and the organic resin particles include methacrylic acid ester polymer particles and acrylic acid ester. Polymer particles, styrene-methacrylic acid ester copolymer particles,
Examples thereof include styrene-acrylic acid ester copolymer particles, core-shell type particles in which the core is a styrene polymer and the shell is a methacrylic acid ester polymer. Of these, silicon dioxide particles and titanium oxide particles are preferable, particles whose surface is subjected to a hydrophobic treatment are preferable, and silicon dioxide particles subjected to a hydrophobic treatment are particularly preferable. The amount of the external additive is not particularly limited, but is usually 0.1 to 6 parts by weight with respect to 100 parts by weight of the toner. Adhesion of external additives is
Usually, the external additive and the toner are put in a mixer such as a Henschel mixer and stirred.

[0044]

EXAMPLES The production method of the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples. In addition, in the following examples, the electrical conductivity B of the filtrate obtained by dehydration immediately before the arbitrarily set drying step
Was set to 200 μS / cm. Parts and% are based on weight unless otherwise specified. The method for measuring physical properties in the present invention is as follows. (1) Volume average particle diameter Toner volume average particle diameter (dv) and particle diameter distribution (dv / d)
p) is a Multisizer (Beckman Coulter)
It was measured by. The measurement with this Multisizer was performed under the conditions of an aperture diameter: 100 μm, a medium: Isoton II, a concentration of 10%, and the number of measured particles: 100,000. (2) Circularity The circularity is the flow type particle image analyzer FPIA-2100.
(Manufactured by Sysmex Corporation), 1.5 μm to 150 μm
It was measured in the range of μm.

(3) Residual metal ion content The residual metal ion content was measured using an inductively coupled plasma emission spectroscopic analyzer (ICP, Seiko Instruments Inc.). (4) Image evaluation Commercially available non-magnetic one-component development type printer (24-sheet machine)
The toner to be evaluated is put into the developing device of this printer, and the temperature is 35 ° C. and the humidity is 80%.
After being left for a whole day and night in a low temperature and low humidity environment of a temperature of 10 ° C. and a humidity of 20%, printing was performed on a copy paper as a transfer material at a print density of 5%. Regarding the image evaluation, the image of the transfer material at the initial stage of printing was visually observed and evaluated according to the following criteria. ◯: The image density is high and no stain is observed on the transfer material. X: The image density was low, and stains were observed on the transfer material.

(Example 1) 80.5 parts of styrene and n
-Polymer methacrylic acid ester macromonomer composed of 19.5 parts of butyl acrylate, polymethacrylic acid ester macromonomer (trade name "AA6", manufactured by Toagosei Co., Ltd., Tg = 94)
C) 0.3 part, divinylbenzene 0.5 part, t-dodecyl mercaptan 1.2 part, carbon black (manufactured by Mitsubishi Chemical Co., trade name "# 25B") 7 parts, charge control agent (Hodogaya Chemical Co., Ltd.) , Product name "Spiron Black TRH")
1 part and 10 parts of dipentaerythritol hexamyristate (endothermic peak temperature of 65 ° C.) as a release agent were wet pulverized using a media type wet pulverizer to obtain a polymerizable monomer composition for core.

On the other hand, an aqueous solution prepared by dissolving 10.2 parts of magnesium chloride in 250 parts of ion-exchanged water was added with 5 parts of ion-exchanged water.
An aqueous solution prepared by dissolving 6.2 parts of sodium hydroxide in 0 parts was gradually added with stirring to prepare a magnesium hydroxide colloidal dispersion. When the particle size distribution of the produced colloid was measured with a Microtrac particle size distribution measuring device (manufactured by Nikkiso Co., Ltd.), Dp50 (50% cumulative value of number particle size distribution) was 0.35 μm, and Dp90 ( 9 of particle size distribution
The 0% cumulative value) was 0.85 μm. In the measurement by this Microtrac particle size distribution measuring instrument, measurement range = 0.12 to 704 μm, measurement time = 30 seconds, medium =
It was carried out under the condition of ion-exchanged water.

On the other hand, 3 parts of methyl methacrylate and 10 parts of water
0 part was finely dispersed by an ultrasonic emulsifier to obtain an aqueous dispersion of the polymerizable monomer for shell. The particle size of the droplets of the polymerizable monomer for shell was determined by adding the obtained droplets to a 1% aqueous solution of sodium hexametaphosphate at a concentration of 3% and measuring it with a Microtrac particle size distribution analyzer. .6μ
It was m.

The polymerizable monomer composition for cores was added to the magnesium hydroxide colloidal dispersion obtained above,
Stir until the droplets become stable, add 6 parts of a polymerization initiator: t-butylperoxy-2-ethylhexanoate (trade name "Perbutyl O" manufactured by NOF CORPORATION), and then use an Ebara Milder By high shear stirring for 30 minutes at a rotation speed of 15,000 rpm to granulate droplets of the monomer mixture. The aqueous dispersion of the granulated monomer mixture was placed in a reactor equipped with a stirring blade, the polymerization reaction was initiated at 85 ° C., and the polymerization conversion rate reached to about 100%. A water-soluble initiator in an aqueous dispersion of monomers (manufactured by Wako Pure Chemical Industries, Ltd., trade name "VA-086" = 2,2'-azobis (2-methyl-
N- (2-hydroxyethyl) -propionamide))
After dissolving 0.3 parts, it was placed in the reactor. After continuing the polymerization for 4 hours, the reaction liquid was cooled to 30 ° C. to stop the polymerization, and an aqueous dispersion (slurry) of colored particles was obtained.

Sulfuric acid was added to the slurry obtained above while stirring, and stirring was continued for 10 minutes to adjust the pH of the system.
Was set to 4.5 or less, and the magnesium hydroxide as the dispersion stabilizer was made soluble in water. Next, the acid-washed slurry was dehydrated using a siphon peeler type centrifuge (manufactured by Mitsubishi Kakoki Co., Ltd., model name "HZ40Si"), and after further repeating water washing and dehydration 3 times, drying was carried out to obtain colored particles. It was made. The volume average particle diameter (dv) of the obtained colored particles is 7.2 μm, and the particle diameter distribution (dv /
dp) was 1.18, and the circularity by a flow type particle analyzer was 0.96. Table 1 shows the electric conductivity of the separated liquid obtained by dehydration after acid washing, the electric conductivity of the separated liquid obtained by dehydration performed 3 times, and the charge amount and residual magnesium ion amount of the toner obtained by drying. Show. As can be seen from the table, the electric conductivity A of the aqueous medium used in the final washing is 200 μS / cm, and the electric conductivity B of the separated liquid separated from the colored particles by the dehydration after the final washing is 230 μS.
/ Cm, the ratio A / B was 0.87. The experiment was repeated 6 times under the same conditions. The conditions of dehydration and washing in the washing process using a siphon peeler type centrifuge were as follows. Filtration area: 0.25 m ² Slurry supply amount: 120 kg Centrifugal effect: 2000 G Amount of washing water: 40 kg / times Number of times of washing: 3 times / lot Electric conductivity of washing water: 1 to 2 times 2 μS / cm, 3 times to 3 times 200 μS / cm

[0051]

[Table 1]

Hydrophobized colloidal silica (made by Nippon Aerosil Co., Ltd., trade name "RX-2" is added to the above colored particles.
00 ") was mixed to prepare a toner. As a result of printing evaluation using the above toner, as can be seen from the table, in all the toners obtained by the experiment repeated 6 times, the image density was high in both the low temperature and low humidity environment and the high temperature and high humidity environment. Clear print with no fogging or unevenness was obtained.

(Example 2) A toner was obtained in the same manner as in Example 1 except that the conditions of dehydration / washing were changed as follows in the washing step. Machine type: HZ40Si Filtration area: 0.25 m ² Slurry supply amount: 120 kg Centrifugal effect: 2000 G Amount of washing water: 40 kg / times Number of times of washing: 3 times / lot Electric conductivity of washing water: 180 μS / cm for the first to third times

The results obtained by repeating the washing six times are shown in Table 2. The obtained toner was evaluated for printing in the same manner as in Example 1. As a result, all the toners obtained in the experiment repeated six times had high image density and fogging in both low temperature and low humidity environment and high temperature and high humidity environment. A clear and even print was obtained.

[0055]

[Table 2]

(Comparative Example 1) A toner was obtained in the same manner as in Example 1 except that the conditions of dehydration / washing were changed as follows in the washing step. However, the dehydration rate of the slurry was adjusted so that the electric conductivity of the separated liquid separated from the colored particles by the dehydration after the final washing was the same as in Example 1. Machine type: HZ40Si Filtration area: 0.25 m ² Slurry supply amount: 120 kg Centrifugal effect: 2000 G Amount of washing water: 40 kg / times Number of times of washing: 3 times / lot Electric conductivity of washing water: 1 to 3 times 2 μS / cm

Table 3 shows the results of repeating the washing six times. As can be seen from the table, by adjusting the electrical conductivity of the separation liquid separated from the colored particles by dehydration after the final washing by reducing the dehydration rate of the slurry, the separation liquid separated from the colored particles by dehydration after the final washing The variation in electrical conductivity was large, and the variation in the charge amount of the obtained toner was also large. Further, by lowering the dehydration rate of the slurry, the drying time is extended, and there arises a problem that toner aggregation occurs due to the drying. The obtained toner was evaluated for printing in the same manner as in Example 1. As a result, the sample separated from the colored particles by dehydration after the final washing has a high electric conductivity and the toner has a low charge amount. Fog occurred, and the separation liquid separated from the colored particles by the dehydration after the final washing had a low electric conductivity, and the sample having a high toner charge amount had paper stains under low temperature and low humidity.

[0058]

[Table 3]

[0059]

According to the present invention, in the production of toner, in the step of washing the toner, the electric conductivity A of the aqueous medium used in the final washing is 10 in the washing step.
˜500 μS / cm, and the electrical conductivity B of the separated liquid separated from the colored particles by dehydration after the final washing is 10 to 500.
By setting μS / cm and setting the ratio (A / B) to 0.5 to 1.5, it becomes possible to keep the chargeability of the toner for each production lot constant, thereby improving the image characteristics and In particular, it is possible to provide a method for producing a toner in which image characteristics are dramatically stable under high temperature and high humidity and low temperature and low humidity.

Claims (5)

[Claims] 1. Colored particles obtained by polymerizing a polymerizable monomer composition containing at least a polymerizable monomer and a colorant in an aqueous medium containing a dispersion stabilizer, A toner manufacturing method comprising a washing step of washing / dehydrating with an aqueous medium and a drying step of drying colored particles, wherein the electrical conductivity A (μS / cm) of the aqueous medium used in the final washing in the washing step is , The electric conductivity B (μS / c) of the separated liquid separated from the colored particles by the dehydration after the final washing.
A method for producing a toner, wherein m) satisfies the following relational expressions (1), (2) and (3). 10 ≦ A ≦ 500 (1) 10 ≦ B ≦ 500 (2) 0.5 ≦ A / B ≦ 1.5 (3) 2. The electric conductivity of the cleaning in the cleaning step is 10 to 10.
Repeatedly in an aqueous medium of 500 μS / cm.
A method for producing the toner described above. 3. The electric conductivity of 10 to 5 used in the washing step.
The method for producing a toner according to claim 1, wherein the aqueous medium of 00 μS / cm contains a polyvalent metal ion. 4. The method for producing a toner according to claim 1, wherein at least one of a vacuum filtration method, a pressure filtration method and a centrifugal separation method is used as a method for dehydrating the colored particles from an aqueous medium. Method. 5. The method for dehydrating colored particles from an aqueous medium uses at least one of vacuum filtration with a continuous belt filter, pressure filtration with a filter press, centrifugal separation with a siphon peeler centrifuge or a decanter centrifuge. The method for producing the toner according to claim 1.