JP2003287928A - Method for manufacturing polymerization toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing polymerization toner by which a polymerizable monomer composition dispersed in an aqueous dispersion medium can be stability polymerized in an industrial scale without decreasing the stability of polymerizable liquid drops of the composition, and moreover, occurrence of scales or aggregates in a polymerization tank can be significantly suppressed. <P>SOLUTION: Liquid drops of a polymerizable monomer composition containing at least a polymerizable monomer and a colorant are produced in a first aqueous dispersion medium (A) containing a dispersion stabilizer to prepare a first aqueous dispersion liquid (B) having dispersion of the liquid drops. The first aqueous dispersion liquid (B) is mixed with a second aqueous dispersion medium (C) containing 0.1 to 5 wt.% of a dispersion stabilizer to prepare a second aqueous dispersion liquid (D) containing the second aqueous dispersion medium (C) by 10 to 150 parts by weight with respect to 100 parts by weight of the polymerizable monomer in the first aqueous dispersion liquid (B). Then the liquid is subjected to polymerization in the polymerization tank. <P>COPYRIGHT: (C)2004,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 polymerized toner used in a printing machine, a copying machine or the like for forming an image by an electrophotographic method, and more specifically, a polymerized toner dispersed in an aqueous dispersion medium. Polymerized toner capable of performing a stable polymerization operation on an industrial scale without impairing the stability of the droplets of the monomer composition, and capable of remarkably suppressing the generation of scales and aggregates in the polymerization container. Manufacturing method.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic apparatus or an electrostatic printing apparatus, a toner for developing an electrostatic charge image (hereinafter abbreviated as "toner") is used as a developer for developing an electrostatic latent image.
Is used. As the toner, colored particles in which an additive component such as a colorant, a charge control agent, and a release agent is dispersed in a binder resin are generally used.

Conventionally, as a toner, a pulverized toner obtained by pulverizing and classifying a resin composition obtained by melting and mixing a colorant and other additives in a thermoplastic resin has been the mainstream. The diameter of the polymerized toner is easy to control, complicated processes such as crushing and classification can be omitted, and polymerized toners with good image quality are widely used.

The polymerized toner generally has a high shearing force by introducing a polymerizable monomer composition containing at least a polymerizable monomer and a colorant into an aqueous dispersion medium containing a dispersion stabilizer. It is produced by a method of dispersing using a stirrer to form droplets of the polymerizable monomer composition, and then polymerizing with a polymerization initiator.

When producing polymerized toner on an industrial scale,
Generally, in a separate container or mixing device, after preparing an aqueous dispersion in which droplets of the polymerizable monomer composition are dispersed in an aqueous dispersion medium containing a dispersion stabilizer, the aqueous dispersion is polymerized. (That is, it is charged in the polymerization reactor) to carry out the polymerization reaction. The reason is that if an aqueous dispersion containing droplets of a polymerizable monomer composition is prepared in a polymerization vessel and polymerization is performed in the same polymerization vessel as it is, a large amount of scale and coarse particles are likely to be generated. Is.

In recent years, in the electrophotographic image forming apparatus, demands for high image quality, high printing speed, colorization, energy saving, cost reduction, miniaturization and the like are increasing, and these demands are met. Therefore, various improvements have been demanded for the polymerized toner. More specifically, (1) to reduce the particle size of the polymerized toner to 10 μm or less, and further to 9 μm or less to improve the definition of the image, and (2) improve the developability and transferability. In order to increase the sphericity of the polymerized toner and to make the particle size distribution sharper, (3) to lower the fixing temperature of the polymerized toner for speeding up printing speed, colorization, energy saving, etc. (4) Increasing the size of the manufacturing apparatus for polymerized toner is the mainstream of the improvement means.

However, if such a means for improving the polymerized toner is adopted, the polymerization reaction system of the polymerized toner tends to become unstable. For example, in order to produce a polymerized toner having a small particle size, when the droplet of the polymerizable monomer composition is formed in the aqueous dispersion medium, the droplet has to be made into a small particle size. The smaller the particle size of, the more the viscosity of the aqueous dispersion containing the droplets increases and the more likely it becomes unstable.

If a releasing agent is added in a larger amount than usual in the polymerizable monomer composition in order to lower the fixing temperature of the polymerized toner, the droplets of the polymerizable monomer composition tend to become unstable. . Further, various pigments used as colorants for colorizing the polymerized toner have high hydrophilicity and have poor dispersibility in the polymerizable monomer as compared with carbon black. A dispersion aid may be added to improve the dispersibility of the pigment. Addition of such a highly hydrophilic pigment or dispersion aid tends to make the droplets of the polymerizable monomer composition unstable.

As described above, the aqueous dispersion containing the minute droplets of the polymerizable monomer composition itself is very easily destabilized. In an aqueous dispersion containing unstable liquid droplets, the liquid droplets are likely to coalesce with each other, or the liquid droplets may be broken. Further, when the aqueous dispersion is put into the polymerization vessel, the droplets are likely to adhere to the inner wall of the polymerization vessel or the like.

In addition to this, when the size of the polymerization container is increased in order to mass-produce the polymerized toner, when the aqueous dispersion liquid in which the droplets of the polymerizable monomer are dispersed is introduced into the polymerization container from the upper part of the polymerization container, the drop is caused. Therefore, the water-based dispersion is likely to collide with the bottom of the polymerization vessel or the like, and the droplets are more likely to be destabilized. Due to the impact caused by dropping when the aqueous dispersion is charged, various things such as coalescence of droplets of the polymerizable monomer composition, destruction of droplets, and adhesion of droplets to the can wall are caused in the polymerization can. Inconvenient phenomenon is likely to occur.

As a result, it becomes difficult to obtain a polymerized toner having a small particle size, a high sphericity and a sharp particle size distribution.
If the particle size distribution of the polymerized toner becomes broad, or if its shape is not spherical but irregular (irregular), the developability and transferability deteriorate. Further, scale is likely to adhere to the inner wall of the polymerization can or a stirring device, and aggregates are likely to be generated at the bottom of the can. The increase in scale and agglomerates not only lowers the yield of the polymerized toner, but also causes a problem such as inclusion of foreign matter in the polymerized toner. Adhesion of scales to the wall of the can lowers the heat transfer coefficient of the polymerization can, making it difficult to control the polymerization temperature and reducing the efficiency of heat transfer from the jacket during polymerization.

Up to now, several methods have been proposed for preventing scale from adhering in the production process of polymerized toner, but they are unsatisfactory as means for solving the above-mentioned problems. For example, JP-A-10-153878 discloses a method of spraying an aqueous dispersion medium in which water or a dispersion stabilizer is mixed on the inner wall of the gas phase portion in the polymerization vessel during suspension polymerization in the polymerization vessel. Has been done. According to this method, it is possible to prevent the scale from adhering to the inner wall of the polymerization vessel or the inner wall of the auxiliary equipment in the vapor phase portion in the polymerization vessel, but there is no scale prevention effect in the liquid phase portion.

In Japanese Patent Laid-Open No. 10-260553, a hydrophilic organic solvent is brought into contact with the inner wall of a polymerization can so that it penetrates into the scale adhering to the inner wall, and then water is sprayed on the inner wall. A method of contacting and removing the scale is disclosed. After washing away the scale,
Polymerization is carried out by introducing a dispersion liquid of a composition containing a monomer and a colorant into a polymerization vessel. According to this method, the scale adhering to the inner wall of the polymerization can can be easily scraped off, but there is no effect of preventing destabilization of the reaction system in the liquid phase part and generation of scale.

Japanese Patent Laid-Open No. 2001-188382 discloses that
There has been proposed a method of cooling a surface of a portion of a member forming a polymerization device for polymerized toner, the portion protruding to a gas phase portion in a polymerization can with a cooling medium. According to this method, the polymerization rate of the unreacted monomer condensed in the protruding portion in the gas phase portion is reduced, or the polymer particles attached to the protruding portion are prevented from drying, and the scale is Adhesion can be suppressed. However, this method does not have a scale preventing effect in the liquid phase portion.

That is, in these known methods, when the instability of the aqueous dispersion containing fine droplets of the polymerizable monomer composition is eliminated or when the aqueous dispersion is charged into the polymerization vessel,
It is not possible to mitigate the increase in instability of the liquid droplets due to collision with the bottom of the polymerization can. In addition, these methods cannot prevent or suppress the generation of scale in the liquid phase portion during polymerization.

[0016]

The object of the present invention is to achieve stable polymerization on an industrial scale without impairing the stability of minute droplets of the polymerizable monomer composition dispersed in an aqueous dispersion medium. It is an object of the present invention to provide a method for producing a polymerized toner, which can be operated and can remarkably suppress the generation of scales and aggregates in the polymerization can.

As a result of intensive studies to achieve the above object, the present inventors have found that a polymerizable monomer composition containing at least a polymerizable monomer and a colorant is added to a dispersion monomer containing a dispersion stabilizer. After being dispersed as droplets in one aqueous dispersion medium, the aqueous dispersion containing the droplets is mixed with a second aqueous dispersion medium containing 0.1 to 5% by weight of a dispersion stabilizer, It has been found that the stability of an aqueous dispersion containing the droplets can be significantly improved even with minute droplets.

Further, when at least a part of the second aqueous dispersion is previously stored in the lower part of the polymerization vessel and the aqueous dispersion containing the droplets is charged from above, the impact caused by dropping is mitigated, It is possible to suppress inconveniences such as coalescence and breakage of droplets. Furthermore, when at least a part of the second aqueous dispersion is introduced into the polymerization vessel while being sprayed on the inner wall of the polymerization vessel, an accessory device in the polymerization vessel, or both, the generation of scale and aggregates is more effective. Can be prevented.

According to such a method, it is possible to stably and efficiently obtain a polymerized toner having a small particle size, a high sphericity, and a sharp particle size distribution. Further, it is possible to remarkably suppress the formation of scales and aggregates, and further to maintain the heat transfer coefficient of the wall of the polymerization vessel at a high level. The present invention has been completed based on these findings.

[0020]

According to the present invention, a polymerizable monomer composition containing at least a polymerizable monomer and a colorant is dropped into an aqueous dispersion medium containing a dispersion stabilizer. In the method for producing a polymerized toner, which comprises a step of polymerizing with a polymerization initiator to produce colored polymer particles after the dispersion, the first aqueous dispersion medium containing (1) a dispersion stabilizer.
In (A), a droplet of a polymerizable monomer composition containing at least a polymerizable monomer and a colorant is formed, and the first aqueous dispersion liquid (B) in which the droplet is dispersed is prepared. Step 1, (2) The first aqueous dispersion (B) is mixed with the second aqueous dispersion medium (C) containing 0.1 to 5% by weight of a dispersion stabilizer, and the first aqueous dispersion (B) is mixed.
Steps 2 and (3) of preparing a second aqueous dispersion (D) containing the second aqueous dispersion medium (C) in an amount of 10 to 150 parts by weight with respect to 100 parts by weight of the polymerizable monomer therein. ) In the polymerization vessel, a series of steps 3 is carried out in which the polymerizable monomer composition dispersed as droplets in the second aqueous dispersion (D) is polymerized with a polymerization initiator to produce colored polymer particles. There is provided a method for producing a polymerized toner, which comprises the steps of:

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION 1. Droplets of polymerizable monomer composition
The first aqueous dispersion- polymerized toner containing can be obtained by polymerizing a polymerizable monomer composition containing at least a polymerizable monomer and a colorant in an aqueous dispersion medium containing a dispersion stabilizer. it can. Prior to the polymerization, the polymerizable monomer composition is put into an aqueous dispersion medium containing a dispersion stabilizer, and dispersed using a stirring device having a high shearing force to obtain the polymerizable monomer composition. , And an aqueous dispersion containing the droplets is prepared.

The polymerized toner having a core-shell structure is obtained by subjecting a polymerizable monomer composition containing at least a polymerizable monomer and a colorant to suspension polymerization in an aqueous dispersion medium containing a dispersion stabilizer. The colored polymer particles thus obtained are used as a core, and the shell polymerizable monomer is polymerized in the presence of the core. The polymer layer formed by polymerizing the shell monomer serves as the shell.

In the production method of the present invention, the first aqueous dispersion containing fine droplets of the polymerizable monomer composition is prepared by the above method, and the first aqueous dispersion is prepared before the initiation of polymerization in the polymerization vessel. The aqueous dispersion and the second aqueous dispersion medium are mixed to prepare a second aqueous dispersion.

The polymerizable monomer composition contains, in addition to the polymerizable monomer and the colorant, a crosslinkable monomer, a macromonomer, a molecular weight adjusting agent, a charge control agent, a release agent, if necessary. Various additives such as lubricants and dispersion aids can be included.

(1) Polymerizable Monomer Examples of the polymerizable monomer for forming the binder resin include monovinyl monomers, crosslinkable monomers and macromonomers. This polymerizable monomer is polymerized and becomes a binder resin component in the polymer particles.

As the monovinyl monomer, specifically,
Aromatic vinyl monomers such as styrene, vinyltoluene and α-methylstyrene; (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid Butyl, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate,
Derivatives of (meth) acrylic acid such as dimethylaminoethyl (meth) acrylate and (meth) acrylamide; monoolefin monomers such as ethylene, propylene and butylene;
Etc.

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 hot offset is effectively improved by using the crosslinkable monomer and the crosslinkable polymer together with the monovinyl monomer. The crosslinkable monomer is a monomer having two or more vinyl groups. Specifically, aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and their derivatives; diethylenically unsaturated carboxylic acid esters such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,4-butanediol diacrylate; N , N-divinylaniline, a compound having two vinyl groups such as divinyl ether, and a compound 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, it is 2 in the molecule.
Examples thereof include esters obtained by subjecting a polymer having one or more hydroxyl groups such as polyethylene, polypropylene, polyester, or polyethylene glycol to an unsaturated carboxylic acid monomer such as acrylic acid or methacrylic acid for condensation reaction.

These crosslinkable monomers and crosslinkable polymers may be used alone or in combination of two or more. The amount used is 100 monovinyl monomers.
Usually 10 parts by weight or less, preferably 0.1 part by weight.
01-7 parts by weight, more preferably 0.05-5 parts by weight,
It is particularly preferably 0.1 to 3 parts by weight.

It is preferable to use the macromonomer together with the monovinyl monomer because it provides a good balance between storage stability at high temperature and fixability at low temperature. The macromonomer has a polymerizable carbon-carbon unsaturated double bond at the end of the molecular chain and has a number average molecular weight of usually 1,000 to 30,0.
00 oligomer or polymer. When the number average molecular weight is within the above range, the fixability and the storability can be maintained without impairing the meltability of the macromonomer, which is preferable.

Examples of the polymerizable carbon-carbon unsaturated double bond at the terminal of the macromonomer molecular chain include an acryloyl group and a methacryloyl group, and a methacryloyl group is preferable from the viewpoint of easy copolymerization. . The macromonomer preferably gives a polymer having a glass transition temperature higher than the glass transition temperature of the polymer obtained by polymerizing the monovinyl monomer.

Specific examples of the macromonomer 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 ones are preferable, and a polymer obtained by polymerizing methacrylic acid ester or acrylic acid ester alone or in combination thereof is preferable.

When the macromonomer is used, its amount is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, based on 100 parts by weight of the monovinyl monomer.
It is more preferably 0.05 to 1 part by weight. When the amount of the macromonomer used is within the above range, the fixability of the toner is maintained and the storage stability is improved, which is preferable.

(2) Colorant As the colorant, various pigments and dyes used in the field of toner such as carbon black and titanium white can be used. Examples of the black colorant include carbon black and nigrosine-based dyes and pigments; magnetic particles such as cobalt, nickel, ferrosoferric oxide, iron manganese oxide, zinc iron oxide, and iron oxide nickel;
When using carbon black, the primary particle size is 20-40
If the value of nm is used, good image quality is obtained, and
It is preferable because the environmental safety of the toner is enhanced. As the colorant for the color toner, a yellow colorant, a magenta colorant, a cyan colorant or the like can be used.

As the yellow colorant, condensed azo compounds, isoindolinone compounds, anthraquinone compounds,
Azo metal complexes, methine compounds, allylamide compounds and the like are used. Specifically, for example, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17, 62,
65, 73, 74, 83, 90, 93, 95, 95, 9
7, 109, 110, 111, 120, 128, 12
9, 138, 147, 155, 168, 180, 181
and so on. In addition, Neftol yellow S, Hansa yellow G, C.I. I. Butt yellow etc. are mentioned.

Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds and perylene compounds. Specifically, for example, C.I. I. Pigment Red 2, 3, 5, 6, 7,
23, 48, 48: 2, 48: 3, 48: 4, 57, 5
7: 1, 58, 60, 63, 64, 68, 81, 81:
1, 83, 87, 88, 89, 90, 112, 114,
122, 123, 144, 146, 149, 163, 1
66, 169, 170, 177, 184, 185, 18
7, 202, 206, 207, 209, 220, 25
1, 254 and the like. In addition, C.I. I. Pigment Violet 19 and the like.

Examples of cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specifically, for example, C.I. I. Pigment Blue 1, 2, 3, 6, 7, 1
5, 15: 1, 15: 2, 15: 3, 15: 4, 16,
17, 60, 62, 66 and so on. In addition, phthalocyanine blue, C.I. I. Bat blue, C.I. I. Acid blue and the like.

These colorants can be used alone or in combination of two or more kinds. The colorant is usually 0.1 per 100 parts by weight of the polymerizable monomer.
It is used in a proportion of -50 parts by weight, preferably 1-20 parts by weight.

(3) Lubricant / dispersion aid For the purpose of uniformly dispersing the colorant in the toner particles, fatty acids such as oleic acid and stearic acid, fatty acids and Na,
A lubricant such as a fatty acid metal salt composed of a metal such as K, Ca, Mg, or Zn; a dispersion aid such as a silane-based or titanium-based coupling agent; and the like may be used. Such lubricants and dispersants are usually 1/100 based on the weight of the colorant.
It is used at a rate of about 0 to 1/1.

(4) Charge Control Agent In order to improve the chargeability of the polymerized toner, it is preferable to add various positively or negatively chargeable charge control agents to the polymerizable monomer composition. Examples of the charge control agent include a metal complex of an organic compound having a carboxyl group or a nitrogen-containing group, a metal-containing dye, nigrosine, and a charge control resin.

Specifically, Bontron N-01 (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 (Hodogaya Chemical Co., Ltd.). Company),
Bontron S-34 (manufactured by Orient Chemical Industry), Bontron E-81 (manufactured by Orient Chemical Industry), Bontron E-84 (manufactured by Orient Chemical Industry), Bontron E
-89 (Orient Chemical Co., Ltd.), Bontron F-2
1 (manufactured by Orient Chemical Industry Co., Ltd.), COPY CHARG
E NX VP434 (made by Clariant), COPY
CHARGENEG VP2036 (manufactured by Clariant), TNS-4-1 (manufactured by Hodogaya Chemical Co., Ltd.), TN
S-4-2 (Hodogaya Chemical Co., Ltd.), LR-147
(Japan Carlit Co., Ltd.), Copy Blue PR (Clariant Co., Ltd.) and other charge control agents; quaternary ammonium (salt)
Examples include charge control resins such as group-containing copolymers and sulfonic acid (salt) group-containing copolymers. Among these, the charge control resin is preferable.

The charge control agent is usually used in an amount of 0.01 to 10 parts by weight, preferably 0.1% by weight, based on 100 parts by weight of the polymerizable monomer.
It is used in a proportion of 1 to 10 parts by weight.

(5) Release Agent A release agent may be contained in the polymerizable monomer composition for the purpose of preventing offset or improving releasability at the time of heat roll fixing. Examples of the releasing agent include 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, wax, jojoba; paraffin, microcrystalline, petrolactam, etc. Petroleum waxes and modified waxes thereof; synthetic waxes such as Fischer-Tropsch wax; polyfunctional ester compounds such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, dipentaerythritol hexamyristate; and the like. These can be used alone or in combination of two or more.

Of these, synthetic waxes, terminal-modified polyolefin waxes, petroleum waxes, polyfunctional ester compounds 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 heating is 30 to 200 ° C, preferably 40 to 160 ° C, more preferably 50 to 120 ° C.
It is particularly preferable to use a polyfunctional ester compound such as a pentaerythritol ester having an endothermic peak temperature or a dipentaerythritol ester having an endothermic peak temperature in the range of 50 to 80 ° C. from the viewpoint of the balance between toner fixability and releasability. .

The endothermic peak temperature at the time of temperature rise is 30 to 200 ° C.
Among the polyfunctional ester compounds such as pentaerythritol ester in the range of 1 and dipentaerythritol ester having the same endothermic peak temperature in the range of 50 to 80 ° C,
It has a molecular weight of 1,000 or more and dissolves in 100 parts by weight of styrene at 25 ° C in an amount of 5 parts by weight or more and an acid value of 10 mg / K
Those having an OH or less are more preferable because they have a remarkable effect on the decrease in the fixing temperature of the toner. The endothermic peak temperature is A
It is the value measured by STM D3418-82.

The release agent is used in an amount of usually 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight, and more preferably 100 parts by weight of the binder resin (polymerizable monomer). 1
10 to 10 parts by weight.

(6) Polymerization initiator As the polymerization initiator, for example, persulfates such as potassium persulfate and ammonium persulfate; 4,4'-azobis (4-
Cyanovaleric acid), 2,2'-azobis [2-methyl-N
-(2-hydroxyethyl) propionamide], 2,
2'-azobis (2-amidinopropane) dihydrochloride,
Azo compounds such as 2,2'-azobis (2,4-dimethylvaleronitrile) and 2,2'-azobisisobutyronitrile; di-t-butyl peroxide, dicumyl peroxide, lauroyl peroxide, benzoyl Peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxypivalate, di-isopropylperoxydicarbonate, di-t-butyl Examples thereof include peroxides such as peroxyisophthalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, and t-butylperoxyisobutyrate. Further, a redox initiator obtained by combining these polymerization initiators and a reducing agent can be used.

Among these, it is preferable to select an oil-soluble polymerization initiator that is soluble in the polymerizable monomer used, and if necessary, a water-soluble polymerization initiator may be used in combination therewith. it can. The polymerization initiator is usually used in a proportion of 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 with respect to 100 parts by weight of the polymerizable monomer. .

The polymerization initiator can be added in advance to the polymerizable monomer composition, but in the case of suspension polymerization, a suspension or emulsion polymerization after the completion of the droplet forming step or during the polymerization reaction. In this case, it can be added directly to the emulsion after the completion of the emulsification step or during the polymerization reaction.

(7) Molecular weight regulator It is preferable to add a molecular weight regulator during polymerization. Examples of the molecular weight modifier include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, 2,2,4,6,6-pentamethylheptane-4-thiol; carbon tetrachloride, tetrachloride. Halogenated hydrocarbons such as carbon bromide; and the like. The molecular weight modifier can be added before the start of the polymerization or during the polymerization. The molecular weight modifier is generally used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer.

(8) Dispersion Stabilizer The dispersion stabilizer used in the present invention preferably contains a colloid of a poorly water-soluble metal compound. Slightly water-soluble metal compounds 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. Substances; aluminum hydroxide, magnesium hydroxide, ferric hydroxide metal hydroxide; and the like. Of these,
The dispersant containing a colloid of poorly water-soluble metal hydroxide is
This is preferable because the particle size distribution of the polymer particles can be narrowed and the sharpness of the image is improved.

The dispersant containing a colloid of a poorly water-soluble metal compound is not limited by its production method, but it is a poorly water-soluble metal obtained by adjusting the pH of the aqueous solution of the water-soluble polyvalent metal compound to 7 or more. It is preferable to use a colloid of a hydroxide, particularly a colloid of a poorly water-soluble metal hydroxide formed by a reaction of a water-soluble polyvalent metal compound and an alkali metal hydroxide in an aqueous phase. The colloid of the poorly water-soluble metal compound has a number particle size distribution D50 (50% cumulative value of the number particle size distribution) of 0.5 μm or less and a D90 (number particle size distribution of 9).
The 0% cumulative value) is preferably 1 μm or less.

The dispersion stabilizer is generally used in a concentration of 0.1 to 5% by weight, preferably 0.2 to 3% by weight, based on the aqueous dispersion medium. If the concentration of the dispersion stabilizer is too low, the droplets of the polymerizable monomer composition tend to be unstable,
Scale and polymer aggregates are easily generated. If the concentration of the dispersion stabilizer is too high, the liquid droplets become too fine, or the viscosity of the aqueous dispersion becomes too high, which lowers the polymerization stability.

In the present invention, a dispersant containing a water-soluble polymer can be used if necessary. Examples of the water-soluble polymer include polyvinyl alcohol, methyl cellulose, gelatin and the like. In the present invention, it is not necessary to use a surfactant,
It can be used for stably carrying out suspension polymerization within a range in which the environmental dependence of the charging characteristics does not become large.

(9) Preparation of First Aqueous Dispersion Medium (A) As the aqueous dispersion medium, water such as ion-exchanged water is generally used. However, if desired, alcohol or the like may be used in combination with water. Good. A predetermined amount of the dispersion stabilizer is added to the aqueous dispersion medium and stirred to prepare the first aqueous dispersion medium (A) containing the dispersion stabilizer. Alternatively, a solution in which a water-soluble polyvalent metal compound is dissolved in an aqueous dispersion medium,
By mixing a solution of an alkali metal hydroxide dissolved in an aqueous dispersion medium and producing a sparingly water-soluble metal hydroxide colloid by reaction in an aqueous phase, the colloid is contained as a dispersion stabilizer. The first aqueous dispersion medium (A) may be prepared.

The ratio of the first aqueous dispersion medium (A) to be used is usually 150 to 1,000 per 100 parts by weight of the polymerizable monomer.
It is 0 part by weight, preferably 250 to 500 parts by weight. If the proportion used is too low, the polymerization stability is lowered, and scales and aggregates are easily generated. If the proportion is too high, the productivity is lowered and the yield is reduced.

(10) First aqueous dispersion containing droplets
Preparation of (B) A polymerizable monomer, a colorant, other additives and the like are mixed using a mixer, and if necessary, wet-milled using a media type wet mill (for example, a bead mill). To obtain a polymerizable monomer composition. The polymerizable monomer composition is dispersed in a first aqueous dispersion medium (A) containing a dispersion stabilizer,
Stir to obtain uniform droplets of the monomer composition (volume average particle size of 5
A primary droplet of about 0 to 1000 μm) is formed. The polymerization initiator may be added after the droplet size becomes uniform in the aqueous dispersion medium in order to avoid early polymerization.

A polymerization initiator is added to and mixed with a suspension in which droplets of the polymerizable monomer composition are dispersed in the first aqueous dispersion medium (A), and further, using a high-speed rotary shearing stirrer. Stir until the particle size of the droplet becomes a small particle size close to the intended toner particle. In this way, minute droplets (volume average particle size of 1
A first aqueous dispersion (B) containing secondary droplets of about 12 μm) is prepared.

The volume average particle size and particle size distribution of fine droplets of the polymerizable monomer composition affect the volume average particle size and particle size distribution of the polymerized toner. If the droplet size is too large, the polymerized toner particles that are generated become large and the resolution of the image decreases. If the droplet size distribution is wide, the fixing temperature varies, and problems such as fog and toner filming occur. Therefore, it is desirable that the droplets are granulated so as to be reduced to the size of the intended toner particles.

The volume average particle diameter of the droplets of the polymerizable monomer composition is usually 1 to 12 μm, preferably 2 to 10 μm, more preferably 3 to 8 μm. In order to obtain a high-definition image, particularly when a polymerized toner having a small particle size is used, the volume average particle size of the liquid droplets is preferably 2 to 9 μm, more preferably 3 μm.
˜8 μm, more preferably about 3 to 7 μm. The particle size distribution (volume average particle size / number average particle size) of droplets of the polymerizable monomer composition is usually 1 to 3, preferably 1 to
2.5, more preferably 1-2. Particularly when granulating fine liquid droplets, an aqueous dispersion medium containing a monomer composition in a gap between a rotor that rotates at high speed and a stator that surrounds the rotor and has small holes or comb teeth. Is preferred.

As the polymerizable monomer, one or more kinds are selected from the above-mentioned monovinyl monomers, and in order to lower the fixing temperature of the toner, the glass transition temperature (Tg) is usually 80 ° C. or lower, preferably 40. -80 ° C, more preferably 50-7
It is preferable to select a monomer or a combination of monomers capable of forming a polymer at about 0 ° C. In the present invention,
The Tg of the copolymer that constitutes the binder resin is a calculated value (calculated T
g).

2. Method of Manufacturing Polymerized Toner According to the conventional method, the first aqueous dispersion liquid (B) in which fine droplets of the polymerizable monomer composition are dispersed is charged into a polymerization container (polymerization reactor) and polymerized. On the other hand, in the present invention, the first aqueous dispersion (B) is mixed with the second aqueous dispersion medium (C) to prepare the second aqueous dispersion (D), and then the polymerization is carried out. By devising the method of preparing the second aqueous dispersion (D), the polymerization reaction can be carried out more stably.

(1) Second aqueous dispersion medium (C) containing a dispersion stabilizer The second aqueous dispersion medium (C) can be prepared in the same manner as the first aqueous dispersion medium (A). That is, the same dispersion stabilizer as that used to disperse the polymerizable monomer composition can be used. Among them,
A colloid of a poorly water-soluble metal hydroxide (for example, magnesium hydroxide colloid) produced by a reaction of a water-soluble polyvalent metal compound and an alkali metal hydroxide in an aqueous phase is preferable. To prepare such a colloidal solution, a solution in which a water-soluble polyvalent metal compound is dissolved in an aqueous dispersion medium and a solution in which an alkali metal hydroxide salt is dissolved in an aqueous dispersion medium are mixed to form an aqueous phase. It is preferable to employ a method of producing a sparingly water-soluble metal hydroxide colloid by the reaction inside.

The concentration of the dispersion stabilizer in the second aqueous dispersion medium (C) is 0.1 to 5% by weight, preferably 0.2 to 3% by weight. If the concentration of the dispersion stabilizer in the second aqueous dispersion medium (C) is too low, the action of improving the stability of the first aqueous dispersion (B) becomes insufficient, and the formation of scales and aggregates is suppressed. The effect becomes smaller. On the other hand, if the concentration of the dispersion stabilizer is too high, the particle size distribution of the polymerized toner may become broad, or the viscosity of the second aqueous dispersion (D) may become too large and become unstable.

(2) Step 1 Step 1 in the production method of the present invention is a step of preparing the above-mentioned first aqueous dispersion (B). That is, the step 1 forms droplets of the polymerizable monomer composition containing at least the polymerizable monomer and the colorant in the first aqueous dispersion medium (A) containing the dispersion stabilizer, First aqueous dispersion in which the droplets are dispersed
This is a step of preparing (B).

(3) Step 2 Step 2 in the production method of the present invention is the first aqueous dispersion.
(B) and a second aqueous dispersion medium (C) containing 0.1 to 5% by weight of a dispersion stabilizer are mixed to obtain 100 parts by weight of the polymerizable monomer in the first aqueous dispersion (B). In contrast, the second aqueous dispersion medium (C)
Second aqueous dispersion containing 10 to 150 parts by weight of
This is a step of preparing (D).

In the first water-based dispersion liquid (B), the dispersion stabilizer contained in the first water-based dispersion medium (A) is consumed by adhering to the periphery of minute droplets and the like. In the presence of a second aqueous dispersion medium (C) containing a dispersion stabilizer,
The new dispersion stabilizer increases droplet stability. On the other hand, if the concentration of the dispersion stabilizer in the first aqueous dispersion medium (A) used first is increased, the droplets of the polymerizable monomer composition become too small, or the viscosity of The increase will be greater.

There are various modes of preparing the second aqueous dispersion (D). As a method of preparing the second aqueous dispersion (D), in a mixing container or a mixing device, the first aqueous dispersion
(B) and a second aqueous dispersion medium (C) are mixed to obtain a second aqueous dispersion
After preparing (D), there is a method in which the second aqueous dispersion (D) is charged into the polymerization vessel.

As another method, the second aqueous dispersion (D) is prepared in the polymerization vessel by introducing the first aqueous dispersion (B) and the second aqueous dispersion medium (C) into the polymerization vessel. There is a way to do it. The first water-based dispersion liquid (B) and the second water-based dispersion medium (C) can be charged into the polymerization vessel at the same time or separately.

The polymerization container may be charged not only from the upper part but also from the lower part through a pipe. After the second aqueous dispersion (C) is charged into the polymerization vessel, the first aqueous dispersion (B) is charged into the polymerization vessel to prepare the second aqueous dispersion (D) in the polymerization vessel. It is preferable.

Further, the first aqueous dispersion (B) and a part of the second aqueous dispersion medium (C) are mixed using a mixing container, a mixing device or the like to prepare an aqueous dispersion (D1). The second aqueous dispersion medium (C) is charged into the polymerization vessel after the rest of the second aqueous dispersion medium (C) is charged into the polymerization vessel, and then the second aqueous dispersion solution (D1) is charged into the polymerization vessel. ) Can be adopted.

In these methods, at least a part of the second aqueous dispersion medium (C) charged in the polymerization vessel is sprayed on the inner wall of the polymerization vessel, an accessory device in the polymerization vessel, or both while spraying the polymerization vessel. It is preferable to put it in the container in order to prevent scale formation and adhesion.

Furthermore, after at least a part of the second aqueous dispersion medium (C) charged in the polymerization vessel is stored in the lower part of the polymerization vessel, the first aqueous dispersion (B) or the aqueous dispersion (D1 It is preferable to add)) into the polymerization container in order to reduce the impact when the first aqueous dispersion (B) or the aqueous dispersion (D1) is added from the top of the polymerization container.

Second aqueous dispersion medium containing dispersion stabilizer
At least a part of (C) is preferably charged in advance in the polymerization container and stored in the lower part thereof, but the charging method is not particularly limited, and it may be charged from the upper part of the polymerization container. Alternatively, it may be introduced from the bottom by using a pipe. As a preferable charging method, a method of spraying (spraying) the second aqueous dispersion medium (C) into the polymerization vessel can be mentioned.

The spraying method will be specifically described with reference to the drawings. FIG. 1 is a sectional view of a polymerization can. In the polymerization vessel (polymerization reactor) 1, a jacket 2 for temperature control, a motor 3 for rotating a stirring blade, a stirring blade 4, and an aqueous dispersion liquid containing droplets of a polymerizable monomer composition ( An inlet 9 for B), a pipe 10 for discharging a reaction liquid (slurry) and the like are arranged. A heating medium or a refrigerant is passed through the jacket to control the temperature inside the polymerization vessel. Hot water is preferable as the heat medium. A shower nozzle 6 is arranged in the polymerization can 1 so that the second aqueous dispersion medium (C) from the pipe 5 can be sprayed into the polymerization can 1.

The second aqueous dispersion medium (C) is charged into the polymerization vessel while being sprayed from the shower nozzle 6 onto the inner wall of the polymerization vessel, the stirring blade, or both. In FIG. 1, the spray liquid 7 is
Although it is sprayed toward the upper part (gas phase part) in the polymerization can 1 to wet the inner wall of the upper part, the spraying direction may be changed to the side wall or the stirring blade. According to the spraying direction shown in FIG. 1, the aqueous dispersion medium (C) sprayed on the inner wall of the upper part of the polymerizer eventually travels along the side wall and reaches the lower part. In this way, the inner wall of the polymerization vessel, the stirring blades, etc. are treated with the second aqueous dispersion medium (C).
It is possible to effectively prevent the scale from adhering by being wet with.

In the production method of the present invention, it is preferable that the second aqueous dispersion medium (C) charged in the polymerization can 1 is stored in the lower part of the polymerization can 1. The second aqueous dispersion medium (C) 8 stored in the lower portion of the polymerization can 1 is the first aqueous dispersion (B) containing droplets of the polymerizable monomer composition, for example, from the charging port 9 to the polymerization can. When thrown in, it absorbs the impact caused by dropping. Polymerization can 1
If the second aqueous dispersion medium (C) is not stored in the lower part of the inside, the first aqueous dispersion (B) directly collides with the bottom of the polymerization vessel, etc., which is undesirable such as coalescence or breakage of droplets. The phenomenon is likely to occur.

In order to store the second aqueous dispersion medium (C) in the lower part of the polymerization vessel, it is necessary to adjust the amount of the input. By spraying only a small amount of the second aqueous dispersion medium (C), it is difficult to store an amount sufficient to reduce the impact at the time of charging the first aqueous dispersion liquid (B) at the bottom of the polymerization vessel. .

In the present invention, the second aqueous dispersion medium (C) containing the dispersion stabilizer is used in a proportion of 10 to 150 parts by weight based on 100 parts by weight of the polymerizable monomer. This proportion is preferably 15 to 130 parts by weight, more preferably 2 parts.
It is 0 to 100 parts by weight. By adjusting the use ratio of the second aqueous dispersion medium (C) within the above range, a sufficient amount of the second aqueous dispersion medium (C) can be stored in the lower part of the polymerization vessel.

If the amount of the second aqueous dispersion medium (C) added is too small, the amount of liquid accumulated in the lower portion of the polymerization container will be too small, and the first aqueous dispersion liquid (B) will be added from the upper portion of the polymerization container. When the method is adopted, the impact at the time of dropping cannot be sufficiently mitigated, and it becomes difficult to suppress the adhesion of scale and the formation of aggregates. Further, if the input amount of the first aqueous dispersion medium (C) is too small, it is not possible to sufficiently wet the inner wall of the polymerization vessel and the stirring blade, and adhesion of the first aqueous dispersion (B) occurs,
As a result, scales are easily generated. If the amount of the second aqueous dispersion medium (C) introduced into the polymerization vessel is too large, the yield may decrease or the efficiency of the polymerization reaction may decrease.

When the first aqueous dispersion (B) and the second aqueous dispersion medium (C) are mixed in advance and then charged into the polymerization vessel,
Since the second aqueous dispersion liquid (D) having improved droplet stability is produced, even if the second aqueous dispersion liquid (D) is introduced from the upper part of the polymerization vessel, coalescence and breakage of the droplets are alleviated. From the viewpoint of the stability of the polymerization reaction system, it is preferable to add the second aqueous dispersion (D) from the lower part of the polymerization vessel through a pipe.

Among the above various methods, the first aqueous dispersion liquid
From the viewpoint of mitigating the impact of (B) from the top of the polymerization vessel and suppressing the formation of scales and aggregates, the second water-based dispersion before the first aqueous dispersion (B) is charged into the polymerization vessel. Medium (C)
To 10 to 150 parts by weight of the polymerizable monomer.
A preferred method is to put the second aqueous dispersion medium (C) in the lower part of the polymerization container by charging it into the polymerization container at a ratio of parts by weight.
Further, at that time, it is preferable to employ a method in which the second aqueous dispersion medium (C) is introduced into the polymerization container while being sprayed on the inner wall of the polymerization container, an accessory device in the polymerization container, or both of them.

(4) Step 3 After the above Step 2, the second aqueous dispersion was placed in the polymerization vessel.
The polymerizable monomer composition dispersed as droplets in (D) is polymerized with a polymerization initiator to form colored polymer particles.
The polymerization temperature is usually 5 to 120 ° C., preferably 35 to 95.
℃. If the polymerization temperature is too low, it is difficult to control the polymerization reaction because a polymerization initiator having high catalytic activity must be used. If the polymerization temperature is too high, when an additive such as a release agent that melts at a low temperature is included, this bleeds onto the surface of the polymerized toner, which may deteriorate the storage stability.

In this polymerization step, if desired, the aqueous dispersion medium may be continuously or intermittently supplied from the shower nozzle 6.
By spraying (C) or water, the upper inner wall in the vapor phase part of the polymerization vessel and other auxiliary devices can be kept in a wet state.

After the step 3, the colored polymer particles can be recovered from the reaction mixture (slurry) to obtain a polymerized toner. In order to obtain polymer particles (capsule toner) having a core / shell structure, the following step 4 is added.

(5) Step 4 In the present invention, the colored polymer particles produced in the above step are used as core particles, and the shell polymerizable monomer is polymerized in the presence of the core particles to coat the core particles. The polymer layer can be formed to produce core-shell type polymer particles (that is, capsule toner). When a water-soluble polymerization initiator is added when the polymerizable monomer for shell is added to the polymerization reaction system, polymer particles having a core-shell type structure are easily produced.

As the polymerizable monomer for the shell, when a polymer which has a Tg higher than the glass transition temperature (Tg) of the polymer component constituting the core particle is used, the storage stability of the toner is improved. be able to. On the other hand, by setting the Tg of the polymer component constituting the core particles to a low value, the fixing temperature of the polymerized toner can be lowered and the melting characteristics can be improved, whereby printing (copying, printing, etc.) It is possible to favorably cope with high speed, full-color, OHP (overhead projector) transparency, and the like.

As the polymerizable monomer for forming the core particles and the shell, preferable ones can be appropriately selected from the above-mentioned monovinyl monomers. As the core polymerizable monomer used in the capsule toner, those capable of forming a polymer having Tg of usually 60 ° C. or lower, preferably 40 to 60 ° C. are suitable. If the glass transition temperature of the polymer component forming the core particles is too high, the fixing temperature will be high, and if it is too low, the storability will be deteriorated. The core polymerizable monomer is often used in combination of two or more kinds of monomers in order to adjust the glass transition temperature. Tg of polymer
Is a calculated value (calculated Tg) calculated according to the type of the polymerizable monomer used and the usage ratio.

The weight ratio of the polymerizable monomer for the core to the polymerizable monomer for the shell is usually 40/60 to 99.9 / 0.1,
It is preferably 60/40 to 99.7 / 0.3, more preferably 80/20 to 99.5 / 0.5. If the proportion of the polymerizable monomer for the shell is too small, the effect of improving the storability is small, and if it is too large, the effect of reducing the fixing temperature is small.

The Tg of the polymer formed from the polymerizable monomer for shell is usually more than 50 ° C. and 120 ° C. or less, preferably more than 60 ° C. and 110 ° C. or less, and more preferably more than 80 ° C. and 105 ° C. or less. The difference in Tg between the polymer formed from the polymerizable monomer for the core and the polymer formed from the polymerizable monomer for the shell is preferably 10 ° C. or higher, more preferably 20 ° C. or higher, especially It is preferably 30 ° C. or higher.
As the polymerizable monomer for the shell, it is preferable to use a monomer such as styrene or methyl methacrylate, which forms a polymer having a Tg of more than 80 ° C., alone or in combination of two or more kinds.

The polymerizable monomer for shell is preferably added to the polymerization reaction system as droplets smaller than the average particle diameter of the core particles. If the droplet size of the polymerizable monomer for shell is too large, it becomes difficult to uniformly form the polymer layer around the core particles. In order to make the shell polymerizable monomer into small droplets, a mixture of the shell polymerizable monomer and the aqueous dispersion medium is subjected to a fine dispersion treatment using, for example, an ultrasonic emulsifier to obtain The dispersion thus obtained may be added to the reaction system. The polymerizable monomer for shell has a solubility of 0.
When it is 1% by weight or more of a relatively water-soluble monomer (for example, methyl methacrylate), it is not necessary to perform a fine dispersion treatment because it easily migrates to the surface of the core particle relatively quickly. It is preferable to carry out a fine dispersion treatment to form such a shell. Polymerizable monomer for shell is 20 ℃
In the case of a monomer having a water solubility of less than 0.1% by weight (for example, styrene), a fine dispersion treatment is carried out, or an organic solvent having a water solubility of 5% by weight or more at 20 ° C. (for example, It is preferable to add (alcohols) to the reaction system to facilitate transfer to the surface of the core particles.

A charge control agent can be added to the polymerizable monomer for the shell. As the charge control agent, those similar to those used in the above-mentioned core particle production are preferable, and when used, they are usually 0.01 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer for shell. Part, preferably 0.1
It is used in a proportion of up to 5 parts by weight.

In order to produce a polymer toner having a core / shell structure, a polymerizable monomer for a shell or its aqueous dispersion is collectively or continuously or intermittently added to a suspension containing core particles. Added to. It is preferable to add a water-soluble radical initiator when adding the polymerizable monomer for the shell, in order to form the shell. When a water-soluble polymerization initiator is added during the addition of the shell polymerizable monomer, the water-soluble polymerization initiator enters near the outer surface of the core particle to which the shell polymerizable monomer has migrated, and the core particle surface It is considered that the polymer (shell) is easily formed in the above.

As water-soluble polymerization initiators, persulfates such as potassium persulfate and ammonium persulfate; 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2 ' -Azobis- [2-methyl-
Examples thereof include azo initiators such as N- [1,1-bis (hydroxymethyl) ethyl] propionamide]. The amount of the water-soluble polymerization initiator is usually 0.1 to 50% by weight, preferably 1 to 20% by weight, based on 100 parts by weight of the polymerizable monomer for shell.

The average thickness of the shell is usually 0.001 to
The thickness is 1.0 μm, preferably 0.003 to 0.5 μm, and more preferably 0.005 to 0.2 μm. If the shell thickness is too large, the fixability will decrease, and if it is too small, the storability will decrease. The core particle diameter and the shell thickness of the polymerized toner can be obtained by directly measuring the particle size and the shell thickness randomly selected from the observation photograph, if they can be observed by an electron microscope. When it is difficult to observe the core and the shell with a microscope, it can be calculated from the particle size of the core particle and the amount of the polymerizable monomer used to form the shell.

3. Polymerized toner The volume average particle diameter (dv) of the polymerized toner (including the capsule toner having a core-shell structure) obtained by the production method of the present invention is usually 1 to 12 μm, preferably 2-1.
It is 1 μm, more preferably 3 to 10 μm. When the resolution is increased to obtain a high-definition image, the volume average particle diameter of the toner is preferably 2 to 9 μm, more preferably 3 to 8 μm.
m, particularly preferably 3 to 7 μm.

The volume average particle diameter (d
The particle size distribution represented by v) / number average particle size (dp) is usually 1.7 or less, preferably 1.5 or less, more preferably 1.3 or less. Volume average particle diameter of polymerized toner (dv)
If is too large, the resolution tends to decrease. If the particle size distribution (dv / dp) of the polymerized toner is large, the ratio of the polymerized toner having a large particle size increases, and the resolution is likely to decrease.

The polymerized toner of the present invention has a sphericity (Sc) represented by a value (Sc / Sr) obtained by dividing an area (Sc) of a circle whose diameter is the absolute maximum length of the particle by the actual projected area (Sr) of the particle. / Sr) is preferably 1 to 1.3, more preferably 1 to 1.2. The use of the substantially spherical polymerized toner improves the transfer efficiency of the toner image on the photoconductor to the transfer material.

4. Developer The polymerized toner of the present invention can be used as a toner component of various developers, but is preferably used as a non-magnetic one-component developer. When the polymerized toner of the present invention is used as a non-magnetic one-component developer, an external additive can be mixed if necessary. Examples of the external additive include inorganic particles and organic resin particles that act as a fluidizing agent and an abrasive.

Examples of the inorganic particles include silicon dioxide (silica), aluminum oxide (alumina), titanium oxide, zinc oxide, tin oxide, barium titanate, and strontium titanate. As the organic resin particles, methacrylic acid ester polymer particles, acrylic acid ester polymer particles, styrene-methacrylic acid ester copolymer particles, styrene-acrylic acid ester copolymer particles, styrene polymer core, methacrylic acid shell Examples thereof include core / shell type particles formed of an ester copolymer.

Among these, inorganic oxide particles are preferable, and silicon dioxide is particularly preferable. The surface of the inorganic fine particles can be hydrophobized, and hydrophobized silicon dioxide particles are particularly preferable. The external additives may be used in combination of two or more kinds. When the external additives are used in combination, a method of combining inorganic particles having different average particle diameters or combining inorganic particles and organic resin particles is 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 polymerized toner. To attach the external additive to the polymerized toner, usually, the polymerized toner and the external additive are put in a mixer such as a Henschel mixer and stirred.

[0103]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Parts and% are based on weight unless otherwise specified. The measuring methods of physical properties and characteristics are as follows.

(1) Particle size of droplets of polymerizable monomer composition Volume average particle size (dv) of the droplets of the polymerizable monomer composition in the aqueous dispersion medium, and volume average particle size ( The particle size distribution represented by the ratio (dv / dp) of the dv) to the number average particle size (dp) was measured by a particle size distribution measuring device (SALD2000A type, manufactured by Shimadzu Corporation). The particle size distribution was measured under the conditions of a refractive index of 1.55 to 0.20i and an ultrasonic wave irradiation time of 5 minutes.

(2) Particle Size and Particle Size Distribution of Polymer Particles Volume average particle diameter (dv) of polymer particles, and ratio of volume average particle diameter (dv) to number average particle diameter (dp) (dv / d
The particle size distribution represented by p) was measured with a Multisizer (manufactured by Coulter). The measurement with this Multisizer was performed under the conditions of an aperture diameter of 100 μm, a medium isoton, a concentration of 10%, and the number of measured particles of 100,000.

(3) Sphericity The sphericity (Sc / Sr) of the polymer particles was determined by taking an electron micrograph of the polymer particles, and using the image processing analyzer Luzex IID [manufactured by Nireco Corporation]. Under the conditions that the area ratio of particles to the frame area is 2% at maximum and the total number of processed particles is 100, the value obtained by dividing the area (Sc) of the maximum outer circle by the substantial cross-sectional area (Sr) is measured, and the measured value is obtained. Is the average value.

(4) Agglomerate amount After the suspension polymerization reaction was completed, the slurry was conveyed from the polymerization vessel to the slurry tank by using a pump. The aggregate remaining on the bottom of the polymerization vessel after the transportation was recovered, dried, and then weighed. The weight of the aggregate is a. Let b be the total solid content weight calculated from the polymerization recipe (assuming 100% complete reaction). Formula "amount of aggregate = (a / b) x 10
The amount of aggregates (% by weight) was calculated by "0". When several batches of suspension polymerization were continuously carried out in the same polymerization vessel, the average value (unit =% by weight / batch) was determined.

(5) Scale Amount After the agglomerate was carried out from the reaction can, the scale adhering to the tube wall and the like was dropped with a water jet, the dropped scale was collected, dried and then weighed. Let A be the weight of the scale. Let B be the total solid content weight calculated from the polymerization recipe (assuming 100% complete reaction).
The scale amount (% by weight) was calculated by the formula “amount of aggregate = (A / B) × 100”. When several batches of suspension polymerization were carried out in the same polymerization vessel, the average value (unit =% by weight / batch) was calculated.

(6) Heat Transfer Coefficient of Polymerization Tube Wall The water temperature on the in and out sides of the jacket arranged on the outer periphery of the polymerization vessel was measured, and the area of the wall of the polymerization vessel in contact with the jacket and the water flowing in the jacket. The flow rate of each was calculated, and the heat transfer coefficient was calculated based on those values.

[Example 1] 1. Preparation of polymerizable monomer composition for core 80.5 parts of styrene, 19.5 of n-butyl acrylate
Part, 0.5 part of divinylbenzene, and 0.5 part of polymethacrylic acid ester macromonomer (trade name “AA6”, manufactured by Toagosei Co., Ltd., Tg = 94 ° C.) polymerizable monomer for core (calculation Tg = about 55 ° C.), carbon black (manufactured by Mitsubishi Chemical Co., trade name “# 25”) 7 parts, charge control resin (manufactured by Fujikura Kasei Kogyo Co., Ltd., trade name “FCF626N”;
1. Styrene resin containing 7% of acrylamide monomer containing sulfonic acid group), and t-dodecyl mercaptan 1.
After stirring and mixing 0 part with a normal stirring device, the mixture was further uniformly dispersed with a media type disperser. Furthermore, 10 parts of dipentaerythritol hexamyristate (solubility in styrene at 25 ° C. = 10 g / 100 g or more, endothermic peak temperature = 65 ° C., molecular weight = 1514) were added,
After mixing and dissolving, a polymerizable monomer composition for core was obtained. The preparation of the polymerizable monomer composition was carried out at room temperature.

2. Preparation of First Aqueous Dispersion Medium To an aqueous solution prepared by dissolving 9.5 parts of magnesium chloride in 250 parts of ion-exchanged water, an aqueous solution prepared by dissolving 5.8 parts of sodium hydroxide in 50 parts of ion-exchanged water was gradually added under stirring. Thus, an aqueous dispersion medium containing magnesium hydroxide colloid (poorly water-soluble metal hydroxide colloid) was prepared. The preparation of this aqueous dispersion medium was carried out at room temperature. The particle size distribution of the colloid was measured with a SALD particle size distribution measuring device (Shimadzu Corporation). As a particle size, D50 (50% cumulative value of number particle size distribution) was 0.36 μm and D90 (number particle size distribution). 90% cumulative value) was 0.80 μm.

3. Droplet Forming Step The above polymerizable monomer composition was added to the aqueous dispersion medium containing the magnesium hydroxide colloid obtained above at room temperature and stirred until the droplets became stable. Then, t-butylperoxy-2-ethylhexanoate (manufactured by NOF CORPORATION, trade name "Perbutyl O") 5 as a polymerization initiator
After adding the parts, high shear stirring was performed for 30 minutes at a rotation speed of 15,000 rpm using an Ebara Milder (manufactured by Ebara Seisakusho) to form droplets of the polymerizable monomer composition. The first aqueous dispersion medium containing droplets of the polymerizable monomer composition is referred to as "first aqueous dispersion".

4. Preparation of aqueous dispersion of polymerizable monomer for shell
Manufactured at room temperature, methyl methacrylate (calculated Tg = 105 ° C)
1 part and 100 parts of water were finely dispersed by an ultrasonic emulsifier to obtain an aqueous dispersion of a 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% sodium hexametaphosphate aqueous solution at a concentration of 3% and measuring with a Microtrac particle size distribution measuring device.
0 was 1.6 μm.

5. Preparation of second aqueous dispersion medium 0.92 parts of sodium hydroxide (alkali metal hydroxide) is dissolved in 7.93 parts of ion-exchanged water in an aqueous solution of 1.51 parts of magnesium chloride dissolved in 39.64 parts of ion-exchanged water. The aqueous solution prepared above was gradually added under stirring to obtain a second aqueous dispersion medium (concentration of magnesium hydroxide colloid = 3.9% by weight) containing a magnesium hydroxide colloid (poorly water-soluble metal hydroxide colloid). Parts were prepared. Hereinafter, this second aqueous dispersion medium is simply referred to as "colloidal solution". 50 parts of this colloidal solution (colloidal concentration = 1.4% by weight)
The number is based on 100 parts of the core polymerizable monomer.

A shower nozzle having a 1.0 mmφ discharge port was arranged above a stainless steel reaction can equipped with a stirrer at the bottom. From this shower nozzle, colloid solution 5
0 part was sprayed from the upper part inside the reaction can to wet the inner wall of the can and the stirring blade, and collected at the bottom of the polymerization can.

6. Suspension Polymerization A first aqueous dispersion liquid containing droplets of a polymerizable monomer composition was charged from the upper part of a reaction can containing a colloidal solution in the lower part. At this time, the colloidal solution accumulated in the lower part of the reaction vessel alleviated the impact due to the drop of the first aqueous dispersion. Also,
The second aqueous dispersion comprising a mixture of the second aqueous dispersion medium (colloidal solution) and the first aqueous dispersion was a dispersion having excellent stability in which droplets were stably dispersed.

The temperature in the polymerization vessel was raised to 90 ° C. to start the polymerization reaction, and when the conversion of polymerization reached almost 100%, sampling was performed and the particle size of the produced colored polymer particles was measured. . As a result, the volume average particle diameter (dv) of the colored polymer particles was 6.4 μm, and the volume average particle diameter (dv) was
/ The number average particle diameter (dp) was 1.18.

Then, an aqueous dispersion of the polymerizable monomer for shell and a water-soluble initiator (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA0
86) Dissolve 0.3 part in 65 parts of distilled water, put this in a reactor and continue the polymerization for 3 hours, and then stop the reaction, and a reaction liquid (slurry) containing polymer particles and having a pH of 9.5. Got

The reaction liquid containing the polymer particles obtained as described above was discharged, and the agglomerates sinking in the bottom of the polymerization vessel were taken out, dried and weighed. Further, the scale adhering to the wall of the polymerization can and the stirrer was washed off with a water jet, and the scale was collected, dried and then weighed.

The thermal conductivity (first time) calculated from the water temperature on the in and out sides of the jacket arranged on the outer periphery of the polymerization can, the area of the jacket in contact with the can wall, and the amount of water flowing through the jacket was 0.37 kW / It was ℃ · m ² .

The same polymerization reaction was repeated 5 times using the same polymerization container. The average value of the amount of aggregates through 5 times of polymerization is
It was 0.1% / batch. Further, the average value of the scale amount was 0.6% / batch, and the polymerized toner could be stably manufactured. On the other hand, the 5th heat transfer coefficient is
The effect was not so large as 0.34 kW / ° C · m ² and the influence of scale was small.

7. Recovery step While the slurry containing the produced polymer particles is stirred at room temperature, acid washing is performed by adjusting the system pH to 4 or less with sulfuric acid,
After separating the water by filtration, a new ion exchange water 500
Parts were added to re-slurry and water washing was performed. afterwards,
Again, dehydration and water washing were repeated several times at room temperature to separate solids by filtration, followed by drying at 45 ° C. for a whole day and night to obtain polymer particles having a core / shell structure.

8. Polymerized toner The volume average particle diameter (dv) of the obtained polymer particles is 6.5 μm.
m, volume average particle diameter (dv) / number average particle diameter (d
p) was 1.16. The shell thickness calculated from the amount of polymerizable monomer for shell and core particle size was 0.03 μm. The sphericity (Sc / Sr) of the polymer particles was 1.2. The glass transition temperature of the polymer particles measured by a differential scanning calorimeter (DSC) was 63 ° C.

9. Non-magnetic one-component developer To 100 parts of the core-shell type polymer particles obtained above, 0.6 part of hydrophobized colloidal silica (trade name: RX300 [manufactured by Nippon Aerosil Co., Ltd.]) was added at room temperature. A non-magnetic one-component developer was prepared by stirring using a Henschel mixer. Image evaluation was carried out using the non-magnetic one-component developer thus obtained, and an image having a high image density of 1.42 and no fog or unevenness and a very good resolution was obtained. .

[Example 2] The colloid concentration of the second aqueous dispersion medium (colloid solution) was changed from 1.4% by weight to 4.0% by weight.
The same operation as in Example 1 was carried out except that the amount was changed from 50 parts to 20 parts. The results are shown in Table 1.

[Example 3] The colloid concentration of the second aqueous dispersion medium (colloid solution) was changed from 1.4% by weight to 0.5% by weight.
The same operation as in Example 1 was carried out except that the amount was changed from 50 parts to 100 parts. The results are shown in Table 1.
Shown in.

[Comparative Example 1] Except that the input amount of the second aqueous dispersion medium (colloidal solution) was changed from 50 parts to 5 parts.
It operated like Example 1. The results are shown in Table 1.

[Comparative Example 2] The same operation as in Example 1 was carried out except that 50 parts of the second aqueous dispersion medium (colloidal solution) charged in the polymerization vessel was changed to 50 parts of ion-exchanged water. The results are shown in Table 1.

[0129]

[Table 1]

[0130]

According to the present invention, a stable polymerization operation on an industrial scale is possible without impairing the stability of droplets of the polymerizable monomer composition dispersed in an aqueous dispersion medium. ,
Moreover, there is provided a method for producing a polymerized toner capable of remarkably suppressing the generation of scales and aggregates in the polymerizer.
According to the production method of the present invention, the stability of an aqueous dispersion containing unstable microdroplets can be improved.

Further, according to the production method of the present invention, even when an aqueous dispersion containing unstable liquid droplets is dropped into a polymerization vessel, the impact caused by falling is caused by the aqueous dispersion medium stored in advance. It is suppressed that the problems such as coalescence and breakage of liquid droplets are alleviated.

According to the production method of the present invention, it is possible to stably and efficiently obtain a polymerized toner having a small particle size, a high sphericity, and a sharp particle size distribution. Further, according to the production method of the present invention, it is possible to prevent the scale from adhering to the inner wall of the polymerization vessel or the like, so that the heat transfer coefficient of the polymerization vessel wall can be maintained high.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a polymerization can used in a manufacturing method of the present invention.

[Explanation of symbols]

1: Polymerization can 2: Jacket 3: Motor of stirring device 4: Stirrer 5: Piping for aqueous dispersion medium 6: Shower nozzle 7: Spray liquid 8: Aqueous dispersion medium accumulated at the bottom of the polymerization can 9: Input port 10: Pipe for discharge

Claims (8)

[Claims] 1. A polymerizable monomer composition containing at least a polymerizable monomer and a colorant is dispersed as droplets in an aqueous dispersion medium containing a dispersion stabilizer, and then a polymerization initiator is used. In a method for producing a polymerized toner, which comprises a step of polymerizing to produce colored polymer particles, (1) at least a polymerizable monomer and a colorant in a first aqueous dispersion medium (A) containing a dispersion stabilizer. A step (1) of forming droplets of a polymerizable monomer composition containing the above and preparing a first aqueous dispersion (B) in which the droplets are dispersed; 1-5% by weight
The second aqueous dispersion medium (C) containing the dispersion stabilizer is mixed, and the second aqueous dispersion medium (C) is added to 100 parts by weight of the polymerizable monomer in the first aqueous dispersion (B). Step 2 of preparing a second aqueous dispersion (D) containing 10 to 150 parts by weight of (2), and (3) in the polymerization vessel, the second aqueous dispersion (D)
Step 3 of polymerizing the polymerizable monomer composition dispersed as droplets therein with a polymerization initiator to produce colored polymer particles
A method for producing a polymerized toner, comprising a series of steps comprising 2. In step 2, the second aqueous dispersion (D) is prepared by mixing the first aqueous dispersion (B) and the second aqueous dispersion medium (C), and then the second aqueous dispersion ( The production method according to claim 1, wherein D) is charged into the polymerization vessel. 3. In step 2, the second aqueous dispersion (D) is charged in the polymerization vessel by introducing the first aqueous dispersion (B) and the second aqueous dispersion medium (C) into the polymerization vessel. Claim 1 to prepare
The manufacturing method described. 4. The second aqueous dispersion (C) is charged into the polymerization vessel, and then the first aqueous dispersion (B) is charged into the polymerization vessel, whereby the second aqueous dispersion ( The method according to claim 3, wherein D) is prepared. 5. In step 2, the first aqueous dispersion (B) and a part of the second aqueous dispersion medium (C) are mixed to prepare an aqueous dispersion (D).
1) is prepared, the second aqueous dispersion medium (C) after the rest is charged into the polymerization vessel, by introducing the aqueous dispersion (D1) into the polymerization vessel, the second aqueous dispersion in the polymerization vessel. The production method according to claim 1, wherein the liquid (D) is prepared. 6. A second aqueous dispersion medium to be placed in a polymerization vessel.
The manufacturing method according to claim 3, wherein at least a part of (C) is charged into the polymerization vessel while being sprayed on the inner wall of the polymerization vessel, an accessory in the polymerization vessel, or both of them. 7. A second aqueous dispersion medium placed in a polymerization vessel.
7. The first aqueous dispersion (B) or the aqueous dispersion (D1) is charged into the polymerization vessel after at least a part of (C) is stored in the lower portion of the polymerization vessel. The manufacturing method according to item 1. 8. A core coated with a polymer layer of colored polymer particles by introducing a shell-forming polymerizable monomer into a polymerization vessel after step 3 and continuing the polymerization.
The production method according to claim 1, wherein step 4 for producing polymer particles having a shell-type structure is added.