JP5444890B2 - Method for producing polymerized toner - Google Patents

Description

  The present invention relates to a method for producing a polymerized toner (hereinafter sometimes simply referred to as “toner”) used for developing an electrostatic latent image in electrophotography, electrostatic recording method, electrostatic printing method and the like. About.

The manufacturing method of the colored resin particles which are the main constituent elements of the toner is roughly classified into a dry method and a wet method.
Examples of the dry method include a pulverization method, which is a method for producing colored resin particles by melt-kneading a binder resin with a colorant and other additives, pulverization, and classification.
On the other hand, examples of the wet method include a polymerization method and a dissolution suspension method, which are methods for producing colored resin particles in an aqueous dispersion medium.

The colored resin particles obtained by the pulverization method are indefinite, whereas the colored resin particles obtained by a wet method such as a polymerization method or a dissolution suspension method are nearly spherical and have a small and sharp particle size. Has a diameter distribution.
Among the wet methods, the polymerization method makes it easy to control the particle size of the toner, and it is possible to produce a polymerized toner having a small particle size and a spherical particle size distribution.

  As the polymerization method, for example, a polymerizable monomer composition containing a polymerizable monomer and a colorant is dispersed in an aqueous dispersion medium to form droplets, the droplets are polymerized, and colored resin particles And a suspension polymerization method for obtaining an emulsion, and an emulsion polymerization aggregation method for polymerizing an emulsified polymerizable monomer to obtain resin fine particles and aggregating them with a colorant or the like to obtain colored resin particles.

  The toner by the polymerization method (polymerized toner) was subjected to a step of solid-liquid separation of the colored resin particles from the aqueous dispersion of colored resin particles, a step of washing the wet colored resin particles (wet cake) that was solid-liquid separated, and washed. It is manufactured through a step of dehydrating an aqueous dispersion containing colored resin particles to form a wet cake (dehydration step) and a step of drying the dehydrated wet cake.

  In recent years, in the above dehydration process, when the total amount of liquid to be processed is increased to 10 to 100 t, a polymerized toner capable of long-term stable operation can be maintained while maintaining the operation efficiency of the dehydration operation over a long period. Development of a production method is required, and various studies have been made on a dehydration operation using a basket-type centrifugal filter, which is generally known to have a high dehydration capacity for a large volume of liquid to be treated.

  For example, in a known basket type centrifugal filter, as shown in the longitudinal sectional view of FIG. 1, the liquid to be treated supplied into the rotating basket rotating at high speed via the stock solution supply pipe is rotated by the action of centrifugal force. The liquid is collected in the radial direction inside, passes through the filter cloth stretched on the inner peripheral surface of the rotating basket, is discharged to the outside of the rotating basket, and the solid content is settled and deposited on the filter cloth surface. Is formed. The wet cake formed on the filter cloth surface is scraped by a scraping blade and discharged outside the machine through a discharge chute.

  In scraping with a scraping blade, the filtration operation is advanced while scraping the wet cake, leaving a thin wet cake layer so that the filter cloth is not damaged by the scraping blade. , The remaining wet cake layer is compacted by centrifugal force to form a hard-to-filter hard layer (hereinafter referred to as “residual layer”), and a liquid passage (gap) is secured. It became difficult, and the filtration resistance was increased, resulting in a decrease in dewatering capacity per unit time.

  Conventionally, when a difficult-to-filter residual layer is formed as described above and the dewatering capacity decreases, the operation of the basket-type centrifugal filter is stopped, and it adheres to the filter cloth surface of the rotating basket. A method has been employed in which the remaining layer is removed manually using a knife, a scraper or the like. However, such a manual removal of the residual layer requires a lot of labor and time, and the operation efficiency of the dehydration operation cannot be maintained over a long period of time, resulting in a decrease in production efficiency.

  In Patent Document 1, as a method of removing the hardly filterable residual layer, a gas injection pipe for injecting pressurized gas is injected along the cutting edge of the scraping blade on the back surface side of the scraping blade. There is disclosed a cake scraping and removing device characterized in that it is fixed to the cake.

JP-A-10-180143

  However, Patent Document 1 does not investigate whether the level is applicable to a method for producing a polymerized toner capable of long-term stable operation while maintaining the operation efficiency of the dehydration operation over a long period of time.

  The present invention has been accomplished in view of the above-mentioned circumstances, and an object of the present invention is to maintain the operation efficiency of the basket-type centrifugal filter over a long period in the dehydration process, and to perform the discharge in the discharge recovery process. When the wet cake is discharged through the chute, the wet cake is prevented from adhering to the inner wall of the discharge chute and blocking the discharge port, and the wet cake with a low moisture content can be efficiently recovered for long-term stable operation. Another object of the present invention is to provide a method for producing a polymerized toner.

  The present inventor has sufficiently studied a method for producing a polymerized toner capable of long-term stable operation through dehydration operation by a basket type centrifugal filter, which has not been sufficiently studied in Patent Document 1. As a result of intensive studies to achieve the above object, it is possible to suitably separate the hardly filterable residual layer from the filter cloth surface by specifying the injection angle of the pressurized gas in the dehydration process, and in the discharge recovery process. Found that the discharge chute can be vibrated and / or the pressurized gas is injected along the inner wall of the discharge chute to prevent the discharge port from being blocked, and the present invention is based on these findings. It came to completion.

That is, the method for producing a polymerized toner of the present invention includes a step of forming colored resin particles by a polymerization method to obtain a colored resin particle aqueous dispersion, and a separation for separating and washing the colored resin particles in the colored resin particle aqueous dispersion. The washing step, the separated and washed colored resin particles, provided with a rotating basket having a filter cloth surface, a scraping blade adjacent to the filter cloth surface, first and second pressurized gas injection ports, and a discharge chute Dewatering using a basket-type centrifugal filter to form a wet colored resin particle (wet cake) layer in the centrifugal filter, a wet cake layer formed on the filter cloth surface of the rotating basket, discharge recovery step of discharging and recovering by drop into the discharge chute by scraping above the scraping blade, as well as the discharge recovered wet cake, of polymerized toner comprising a drying drying step A manufacturing method,
In the dehydration step, the wet cake layer formed on the filter cloth surface of the rotating basket, the rotating direction opposite to the direction of the rotating basket against the scraper blade is brought scraped the wet cake layer, those該掻In peeling off the residual layer by spraying pressurized gas onto the wet cake layer (residual layer) remaining on the filter cloth surface without being scraped off by the cutting blade,
1) A line segment connecting the point at which the scraping blade contacts the residual layer and the center point of the rotating shaft of the rotating basket, with the scraping blade and the first pressurized gas injection port disposed above the discharge chute. And an angle (θ ₁ ) formed by a line connecting the point where the pressurized gas injected from the first pressurized gas injection port hits the residual layer and the center point of the rotation axis of the rotating basket is a scraping direction. In the range of 270 ° to less than 360 °,
2) An angle (θ ₂ ) between a line segment connecting the center point of the first pressurized gas injection port and a point where the pressurized gas hits the residual layer and a tangent at the point where the pressurized gas hits the residual layer is , In the range of 20 ° or more and less than 90 °,
In the discharge and recovery process, in discharging and collecting the wet cake obtained through the dehydration process to the outside through the discharge chute,
3) Before and after discharging the wet cake, the discharge chute is vibrated and / or the pressurized gas is injected along the inner wall of the discharge chute from the second pressurized gas injection port provided on the inner wall of the discharge chute. It is characterized by doing.

In the method for producing the polymerization toner, an injection nozzle having the first pressurized gas injection port is installed on the back side of the scraping blade, and the pressure of the pressurized gas injected from the injection port is 0. It is preferably 1 to 1.5 MPa.

In the method for producing the polymerized toner, in the dehydration step, after the colored resin particles in the colored resin particle aqueous dispersion are aggregated, they are dehydrated using a basket type centrifugal filter,
The number average particle diameter (Dn ₂ ) of the colored resin particles after the aggregation and before the dehydration step by the basket type centrifugal filter, and the number of the colored resin particles after the step of obtaining the colored resin particle aqueous dispersion and before the separation washing step The ratio (Dn ₂ / Dn ₁ ) to the average particle diameter (Dn ₁ ) is preferably 1.2 to 2.0.

  According to the method for producing a polymerized toner of the present invention as described above, the wet cake is discharged through the discharge chute in the discharge recovery step while maintaining the operation efficiency of the basket type centrifugal filter for a long period in the dehydration step. A method for producing a polymerized toner that prevents the wet cake from adhering to the inner wall of the discharge chute and clogging the discharge port, efficiently recovers the wet cake having a low water content, and enables stable long-term operation. Provided.

FIG. 1 is a schematic longitudinal sectional view of a known basket type centrifugal filter. FIG. 2A shows the injection angle (θ ₁ ) of the pressurized gas, and FIG. 2B shows the injection angle (θ ₂ ) of the pressurized gas. FIG. 3 is a schematic longitudinal sectional view of the basket type centrifugal filter used in the embodiment of the present invention.

The method for producing a polymerized toner of the present invention comprises a step of forming colored resin particles by a polymerization method to obtain a colored resin particle aqueous dispersion, and a separation washing for separating and washing the colored resin particles in the colored resin particle aqueous dispersion. Step, the separated and washed colored resin particles are dehydrated using a basket-type centrifugal filter equipped with a rotating basket and a discharge chute to form a wet colored resin particle (wet cake) layer in the centrifugal filter. A method for producing a polymerized toner comprising a dehydration step, a discharge recovery step of discharging and recovering the wet cake, and a drying step of drying the discharged and recovered wet cake,
In the dehydration step, the scraping blade comes into contact with the wet cake layer formed on the filter cloth surface of the rotating basket from the direction opposite to the rotating direction of the rotating basket, and scrapes off the wet cake layer. In peeling off the residual layer by injecting pressurized gas onto the wet cake layer (residual layer) remaining on the filter cloth surface without scraping with
1) A line segment connecting the point where the scraping blade contacts the residual layer and the center point of the rotation axis of the rotating basket, and a line segment connecting the point where the pressurized gas hits the residual layer and the center point of the rotation axis of the rotating basket angle (theta ₁₎ of is within the range of less than 270 ° 360 ° or more with respect to the scraping direction,
2) The angle (θ ₂ ) between the line segment connecting the center point of the injection port for injecting the pressurized gas and the point where the pressurized gas hits the residual layer and the tangent at the point where the pressurized gas hits the residual layer is Within a range of 20 ° or more and less than 90 °,
In the discharge and recovery process, in discharging and collecting the wet cake obtained through the dehydration process to the outside through the discharge chute,
3) Before and after discharging the wet cake, the discharge chute is vibrated and / or the pressurized gas is injected along the inner wall of the discharge chute from the injection port provided on the inner wall of the discharge chute. It is.

Examples of the polymerization method include a suspension polymerization method, an emulsion aggregation polymerization method, a dispersion polymerization method, and the like. In the method for producing a polymerized toner provided by the present invention, it is preferable to employ a suspension polymerization method.
Hereinafter, a method for producing a polymerized toner by a suspension polymerization method will be described as a representative example.

(1) Step of obtaining colored resin particle aqueous dispersion In this step, (1-1) Step of preparing polymerizable monomer composition, (1-2) Step of obtaining suspension (droplet forming step), And (1-3) A desired colored resin particle aqueous dispersion can be obtained through the respective steps including the polymerization step.

(1-1) Preparation step of polymerizable monomer composition First, a polymerizable monomer, a colorant, a charge control agent added as necessary, and other additives such as a release agent are mixed. Then, the polymerizable monomer composition is prepared by dissolving or dispersing. In preparing the polymerizable monomer composition, for example, a media type dispersing machine is used.

The polymerizable monomer means a monomer having a polymerizable functional group, and the polymerizable monomer is polymerized to become a binder resin. A monovinyl monomer is preferably used as the main component of the polymerizable monomer.
Examples of the monovinyl monomer include styrene; styrene derivatives such as vinyl toluene and α-methylstyrene; acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid 2 Acrylic esters such as ethylhexyl and dimethylaminoethyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and dimethylaminoethyl methacrylate; acrylamide And methacrylamide; olefins such as ethylene, propylene, and butylene; and the like. These monovinyl monomers can be used alone or in combination of two or more.
Of the monovinyl monomers, styrene, styrene derivatives, acrylic acid esters, and methacrylic acid esters are particularly preferably used.

As a part of the polymerizable monomer, any crosslinkable polymerizable monomer can be used together with the monovinyl monomer in order to improve the storage stability (blocking resistance) of the toner. A crosslinkable polymerizable monomer refers to a monomer having two or more polymerizable functional groups.
The crosslinkable polymerizable monomer is not particularly limited as long as it is generally used as a crosslinkable polymerizable monomer for toner, and examples thereof include divinylbenzene, divinylnaphthalene, and these. Aromatic divinyl compounds such as derivatives; bifunctional ethylenically unsaturated carboxylic acid esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; heteroatom-containing divinyl compounds such as N, N-divinylaniline and divinyl ether; And compounds having three or more vinyl groups, such as methylolpropane trimethacrylate and dimethylolpropane tetraacrylate. These crosslinkable polymerizable monomers may be used alone or in combination of two or more.
In the present invention, the crosslinkable polymerizable monomer is usually used at a ratio of 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, with respect to 100 parts by weight of the monovinyl monomer. desirable.

Further, as a part of the polymerizable monomer, an arbitrary macromonomer can be used together with the monovinyl monomer in order to improve the balance between the storage stability and low-temperature fixability of the toner.
The macromonomer is a reactive oligomer or polymer having a polymerizable carbon-carbon unsaturated bond at the end of the molecular chain and having a number average molecular weight (Mn) of usually 1,000 to 30,000. . As the macromonomer, it is preferable to use an oligomer or polymer having a Tg higher than the glass transition temperature (Tg) of a polymer (binder resin) obtained by polymerizing a polymerizable monomer.
In the present invention, the proportion of the macromonomer is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, and more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the monovinyl monomer. It is desirable to use in.

  As the colorant, when producing a color toner (usually, four types of toners of black toner, cyan toner, yellow toner, and magenta toner are used), a black colorant, a cyan colorant, a yellow colorant, and Magenta colorants can each be used.

  As the black colorant, carbon black, titanium black, and pigments such as magnetic powders such as iron oxide zinc and iron oxide nickel can be used.

  As the cyan colorant, for example, a compound such as a copper phthalocyanine pigment, a derivative thereof, and an anthraquinone pigment is used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17: 1, 60, and the like.

  As the yellow colorant, for example, azo pigments such as monoazo pigments and disazo pigments, and compounds such as condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 74, 83, 93, 97, 120, 138, 155, 180, 181, 185, 186, and the like.

  Examples of the magenta colorant include compounds such as monoazo pigments, azo pigments such as disazo pigments, and condensed polycyclic pigments. Specifically, C.I. I. Pigment Red 31, 48, 57: 1, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 149, 150, 163, 170 , 184, 185, 187, 202, 206, 207, 209, 251 and C.I. I. Pigment Violet 19 and the like.

These colorants can be used alone or in combination of two or more.
In the present invention, it is desirable to use the colorant usually at a ratio of 1 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

As other additives, a positively or negatively chargeable charge control agent can be used to improve the chargeability of the toner.
The charge control agent is not particularly limited as long as it is generally used as a charge control agent for toner. Among charge control agents, the charge control agent has compatibility with a binder resin (or polymerizable monomer). High and stable chargeability (charge stability) can be imparted to the toner particles, and therefore a positively or negatively chargeable charge control resin is preferably used. From the viewpoint of obtaining a positively chargeable toner, positive charge The charge control resin is more preferably used.
As the positively chargeable charge control resin, commercially available products manufactured by Fujikura Kasei Co., Ltd. can be used. For example, FCA-161P (: trade name, styrene / acrylic resin), FCA-207P (: trade name, styrene / Acrylic resin) and FCA-201-PS (trade name, styrene / acrylic resin).
As the negatively chargeable charge control resin, a commercial product manufactured by Fujikura Kasei Co., Ltd. can be used. For example, FCA-626N (: trade name, styrene / acrylic resin), FCA-748N (: trade name, styrene / Acrylic resin) and FCA-1001N (trade name, styrene / acrylic resin).
In the present invention, it is desirable to use the charge control agent in a proportion of usually 0.3 to 10 parts by weight, preferably 0.5 to 8 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

As another additive, a release agent can be used to improve the releasability of the toner from the fixing roll.
The release agent is not particularly limited as long as it is generally used as a release agent for toner. For example, polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; candelilla, carnauba Natural waxes such as wax, rice, wax and jojoba; petroleum waxes such as paraffin wax, microcrystalline and petrolatum; mineral waxes such as montan, ceresin and ozokerite; synthetic waxes such as Fischer-Tropsch wax; pentaerythritol tetramyristate Pentaerythritol esters such as pentaerythritol tetrapalmitate, pentaerythritol tetrastearate, and pentaerythritol tetralaurate, and dipentaerythritol Kisa myristate, dipentaerythritol hexa palmitate, and dipentaerythritol esters such as dipentaerythritol hexa laurate, polyhydric alcohol ester compounds such polyglycerol fatty acid ester; and the like. These release agents may be used alone or in combination of two or more.
In this invention, it is desirable to use a mold release agent in the ratio of 0.1-30 weight part normally with respect to 100 weight part of polymerizable monomers, Preferably it is 1-20 weight part.

As other additives, a molecular weight modifier can be used to adjust the molecular weight and molecular weight distribution of the binder resin.
The molecular weight modifier is not particularly limited as long as it is generally used as a molecular weight modifier for toner. For example, t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2, Mercaptans such as 4,6,6-pentamethylheptane-4-thiol; tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N, N′-dimethyl-N, N′-diphenylthiuram disulfide, and N , N′-dioctadecyl-N, N′-diisopropyl thiuram disulfide and other thiuram disulfides; These molecular weight modifiers may be used alone or in combination of two or more.
In the present invention, it is desirable to use the molecular weight modifier in a proportion of usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the polymerizable monomer.

(1-2) Step of obtaining a suspension (droplet forming step)
The polymerizable monomer composition obtained by the preparation process of the above (1-1) polymerizable monomer composition is suspended in an aqueous dispersion medium and suspended (polymerizable monomer composition dispersion). Liquid). Here, the suspension means that droplets of the polymerizable monomer composition are formed in an aqueous dispersion medium. Dispersion treatment for droplet formation is, for example, an in-line type emulsifying disperser (manufactured by Ebara Manufacturing Co., Ltd., trade name: Milder), a high-speed emulsifying / dispersing machine (trade name: TK Homomixer MARK II type). ) And the like, which can be vigorously stirred.

As the aqueous dispersion medium, water alone may be used, but a solvent that is soluble in water, such as lower alcohol and lower ketone, may be used in combination.
In droplet formation, it is preferable to use a dispersion stabilizer in the aqueous dispersion medium in order to control the particle size of the colored resin particles and improve the circularity.

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; metals such as aluminum oxide and titanium oxide. Oxides and metal compounds such as metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; water-soluble polymer compounds such as polyvinyl alcohol, methyl cellulose, and gelatin; anionic surfactants , Organic polymer compounds such as nonionic surfactants and amphoteric surfactants; Among these, metal hydroxide is preferable, and the pH region is usually pH 7.
Magnesium hydroxide used in 5-11 is preferred.

Among the above dispersion stabilizers, a dispersion stabilizer containing a colloid of a hardly water-soluble metal hydroxide (a hardly water-soluble inorganic compound) that is soluble in an acid solution is preferably used. The dispersion stabilizers can be used alone or in combination of two or more.
The amount of the dispersion stabilizer added is preferably 0.1 to 20 parts by weight and more preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

  Examples of the polymerization initiator used for polymerization of the polymerizable monomer composition include inorganic 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, 2,2′-azobis (2,4-dimethylvaleronitrile) ), And azo compounds such as 2,2′-azobisisobutyronitrile; di-t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy- 2-ethylhexanoate, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, di-t-butyl peroxyiso Tallates, and t- butylperoxy isobutyrate and the like organic peroxides;., Etc. Among these, organic peroxides are preferably used.

The polymerization initiator may be added at the stage before the droplet formation after the polymerizable monomer composition is dispersed in the aqueous dispersion medium containing the dispersion stabilizer. It may be added directly to the composition.
The addition amount of the polymerization initiator is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 15 parts by weight with respect to 100 parts by weight of the polymerizable monomer, and 1.0 More preferably, it is 10 weight part.

(1-3) Polymerization step A desired suspension (water system containing droplets of a polymerizable monomer composition) obtained by the step (1-2) step of obtaining a suspension (droplet formation step). The dispersion medium) is heated to initiate polymerization, and an aqueous dispersion of colored resin particles is obtained.
The polymerization temperature in the present invention is preferably 50 ° C. or higher, and more preferably 60 to 98 ° C. Further, the polymerization time in the present invention is preferably 1 to 20 hours, and more preferably 2 to 15 hours.
In addition, in order to carry out the polymerization in a state where the droplets of the polymerizable monomer composition are stably dispersed, the step (1-2) for obtaining the suspension (droplet formation step) also in the main polymerization step. Subsequently, the polymerization reaction may be allowed to proceed while performing a dispersion treatment by stirring.

As colored resin particles having a core-shell structure (or also referred to as “capsule type”) obtained by forming colored resin particles obtained by the polymerization step as a core layer and forming a shell layer different from the core layer on the outer side thereof. Good.
The colored resin particles having a core-shell structure are formed by coating a core layer made of a material having a low softening point with a shell layer, which is a material having a higher softening point, thereby reducing the fixing temperature of the toner and agglomeration during storage. It is possible to balance prevention.

  There is no restriction | limiting in particular as a method of manufacturing the said core-shell type colored resin particle, It can manufacture by a conventionally well-known method. An in situ polymerization method and a phase separation method are preferable from the viewpoint of production efficiency.

A method for producing core-shell type colored resin particles by in situ polymerization will be described below.
By adding a polymerizable monomer for forming a shell layer (polymerizable monomer for shell) and a polymerization initiator for shell into an aqueous dispersion medium in which colored resin particles are dispersed, and performing polymerization. Core-shell type colored resin particles can be obtained.

  As the polymerizable monomer for the shell, the same polymerizable monomer as described above can be used. Among them, it is preferable to use monomers such as styrene and methyl methacrylate, which can produce a polymer having a Tg exceeding 80 ° C., alone or in combination of two or more.

Examples of the shell polymerization initiator used for the polymerization of the shell polymerizable monomer include potassium persulfate and persulfate metal salts such as ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxy Water-soluble azo compounds such as ethyl) propionamide) and 2,2′-azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide); Mention may be made of initiators.
The addition amount of the polymerization initiator for shell is preferably 0.1 to 30 parts by weight, and more preferably 1 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer for shell.

  The polymerization temperature of the shell layer is preferably 50 ° C. or higher, and more preferably 60 to 95 ° C. The polymerization time for the shell layer is preferably 1 to 20 hours, more preferably 2 to 15 hours.

In the colored resin particles obtained through the step (1) of obtaining the colored resin particle aqueous dispersion, the volume average particle size (Dv ₁ ) before the separation and washing step described later is, from the viewpoint of forming a high-quality image, It is preferable that it is 2-10 micrometers, and it is more preferable that it is 3-9 micrometers. The number average particle diameter (Dn ₁ ) is preferably 1.7 to 8.4 μm, and more preferably 2.5 to 7.5 μm.

When the volume average particle diameter (Dv ₁ ) and the number average particle diameter (Dn ₁ ) of the colored resin particles are less than the lower limit, the fluidity of the toner is lowered and the image quality is liable to be deteriorated due to fog or the like. Therefore, the print performance may be adversely affected. On the other hand, when the volume average particle diameter (Dv ₁ ) and the number average particle diameter (Dn ₁ ) of the colored resin particles exceed the upper limit, high-definition image formation becomes difficult and the resolution of the obtained image is lowered. And may adversely affect printing performance.

The volume average particle size (Dv ₁ ) and the number average particle size (Dn ₁ ) are values measured using a particle size measuring machine. For example, a particle size measuring machine (Beckman Coulter, Inc.) (Product name: Multisizer).

(2) Separation and washing step In this step, (2-2) a separation / washing step by a washing apparatus, and (2-3) a step of obtaining a redispersion of colored resin particles, preferably (2-1) acid The dispersion stabilizer is removed by the above-described steps, and the desired washing can be performed through the respective steps.
The series of steps (2-2) to (2-3) can be repeated a plurality of times as necessary.

(2-1) Dispersion Stabilizer Removal Step with Acid The unnecessary dispersion stabilizer remaining in the colored resin particle aqueous dispersion obtained through the step (1) of obtaining the colored resin particle aqueous dispersion is removed. In order to achieve this, it is preferable to remove and wash the dispersion stabilizer by adding an acid.

  When an acid-soluble dispersion stabilizer is used, the pH is adjusted by adding an acid to the colored resin particle aqueous dispersion, and unnecessary dispersion stabilization remaining in the colored resin particle aqueous dispersion is performed. The agent can be removed by dissolving it in an aqueous system.

  The acid added when a dispersion stabilizer soluble in acid is used is not particularly limited, and examples thereof include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid; organic acids such as formic acid and acetic acid; Of these, sulfuric acid is particularly preferably used because of its high removal efficiency of the dispersion stabilizer and low burden on the production equipment.

The pH of the colored resin particle aqueous dispersion prepared by adding an acid is preferably 4 to 7, and more preferably 5 to 6.5.
When the pH of the colored resin particle aqueous dispersion is less than the lower limit, a large amount of washing water may be required for washing due to an increase in the acidity of the colored resin particle aqueous dispersion. On the other hand, when the pH of the colored resin particle aqueous dispersion exceeds the upper limit, it may be difficult to remove the dispersion stabilizer.

(2-2) Separation / washing step by washing device (2-1) As a washing device for separating / washing the colored resin particles obtained through the step of removing the dispersion stabilizer with acid, for example, a belt filter or the like It is preferable to form a wet colored resin particle (wet cake) by solid-liquid separation using water and washing with washing water such as ion exchange water.

  In this step, when a belt filter is used as an apparatus for separation / washing, the colored resin particles obtained through the step (2-1) are supplied to the belt filter, separated into solid and liquid, and wetted. After forming colored resin particles (wet cake) in a state, the washing liquid such as ion-exchanged water is uniformly dropped and supplied to the wet cake, and the colored resin particles in a desired wet state are obtained by performing uniform cleaning. Particles (wet cake) can be formed.

  As the belt filter, for example, a continuous belt filter (trade name: Eagle filter) manufactured by Sumitomo Heavy Industries, Ltd., a vacuum horizontal belt filter (trade name: Daiki ADPPEC filter) manufactured by Ataka Daiki Co., Ltd., and Tsukishima Machine A typical example is a horizontal belt filter (trade name: Tsukishima-horizontal belt filter) manufactured by the company.

The amount of washing water such as ion-exchanged water used for washing is preferably 2 to 20 times, more preferably 3 to 10 times the solid content in the colored resin particle aqueous dispersion. 3 to 6 times the amount is more preferable.
When the amount of the washing water is less than the lower limit, the impurities contained in the wet cake are not sufficiently removed by washing, which may adversely affect the toner printing performance. On the other hand, when the amount of the cleaning water exceeds the upper limit, cleaning more than necessary is performed, which may reduce toner productivity.

(2-3) Step of obtaining colored resin particle re-dispersion liquid (2-2) Wet colored resin particles (wet cake) obtained through the separation and washing step by the washing device are re-dispersed in ion-exchanged water. When the redispersion of colored resin particles having a solid content concentration of 20% by weight is prepared, the colored resin is used until the electric conductivity of the filtrate obtained by filtering the redispersion is 500 μS / cm or less. After increasing the degree of cleaning of the particles, the colored resin particles are preferably redispersed in ion exchange water to obtain a redispersion of colored resin particles having a predetermined solid content concentration.
The electrical conductivity of the filtrate can be used as an index when determining the level of cleaning degree of the colored resin particles.

The electric conductivity of the filtrate obtained by filtering the re-dispersion of colored resin particles is preferably 500 μS / cm or less, more preferably 100 μS / cm or less, and further preferably 50 μS / cm or less. preferable.
When the electrical conductivity of the filtrate exceeds the above upper limit, it can be determined that the level of washing degree of the colored resin particles is low and the washing of the colored resin particles is insufficient, and the above (2-2) to (2 It is necessary to increase the level of cleanliness of the colored resin particles by repeating the series of steps -3).
In addition, electrical conductivity is a value measured using an electrical conductivity meter, and can be measured using, for example, an electrical conductivity meter (trade name: ES-12) manufactured by Horiba, Ltd.

  In this step, the redispersed liquid of colored resin particles having a solid content concentration of 20% by weight is a condition for measuring electrical conductivity, which is an index of the degree of cleaning of colored resin particles. It does not mean that the re-dispersed liquid of colored resin particles having a solid content concentration of 20% by weight is used in the next step (3) by-product fine particle removing step.

In this step, colored resin particles that have been found to have a high degree of cleaning of the colored resin particles from the results of the electrical conductivity measurement test are obtained at the final stage of the separation and washing step, and ion-exchanged water is obtained. It means that it is only necessary to obtain a redispersion of colored resin particles by redispersing to an appropriate solid content concentration.
The appropriate solid content concentration is preferably 15 to 35% by weight, more preferably 20 to 25% by weight, and can be used in the next step (3) by-product fine particle removing step.

  For example, in the step (2-2), a part of the wet colored resin particles (wet cake) formed on the belt filter is collected and re-dispersed in ion-exchanged water to obtain a solid content concentration. If the electric conductivity of the filtrate obtained by filtering the redispersed liquid is 500 μS / cm or less, the remaining wetness formed on the belt filter is obtained. The colored resin particles (wet cake) in the state can be determined as colored resin particles that have been increased to a desired degree of cleaning.

(3) By-product fine particle removal step In this step, (3-1) pH adjustment step of redispersion of colored resin particles, (3-2) removal step of by-product fine particles, and (3-3) colored resin particles In addition, a desired by-product fine particle can be removed through each step.

(3-1) Color resin particle re-dispersion pH adjusting step (2) Color resin particle re-dispersion solution obtained through the above-mentioned separation and washing step is adjusted to alkaline pH, dispersed, and colored resin particle surface It is preferable to release by-product fine particles adhering to the colored resin particles.

The pH after adjusting the pH of the colored resin particle redispersion liquid is preferably 9 to 12, and more preferably 9.5 to 11.5.
When the pH after pH adjustment of the redispersion of the colored resin particles is less than the lower limit, the by-product fine particles adhering to the colored resin particle surfaces cannot be sufficiently released from the colored resin particles, In the next step (4-2), a dewatering step using a basket-type centrifugal filter may cause clogging of the filter cloth, which may reduce the dewatering efficiency and adversely affect printing performance. On the other hand, when the pH after pH adjustment of the redispersion of the colored resin particles exceeds the upper limit, by-product fine particles adhering to the surface of the colored resin particles can be released from the colored resin particles. In the (4-1) colored resin particle agglomeration forming step of the step, in order to agglomerate the colored resin particles, a large amount of an aggregating agent is required, which may reduce the dehydration efficiency.

The alkali used for pH adjustment is not particularly limited as long as the redispersion of the colored resin particles can be adjusted to be alkaline, but it is preferable to adjust the pH using an aqueous solution of an alkali metal hydroxide.
Examples of the aqueous solution of the alkali metal hydroxide include a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution. Among these, a sodium hydroxide aqueous solution is more preferably used.

The alkali used for pH adjustment is preferably used after the concentration is adjusted to a low concentration, and the alkali concentration is preferably 0.01 to 1.0% by weight, more preferably 0.05 to 0.5% by weight, It is more preferable to use an aqueous solution containing 0.07 to 0.3% by weight of alkali adjusted in concentration.
In addition, although the addition amount of the alkali used for pH adjustment changes with the density | concentrations of an alkali, if it adds so that the pH of the re-dispersion liquid of the colored resin particle after adding an alkali may be 9-12, the addition The amount is not particularly limited.

  When the alkali concentration used for the pH adjustment is less than the lower limit, a large amount of alkali is required to release by-product fine particles adhering to the surface of the colored resin particles from the colored resin particles. Since the solid content concentration of the re-dispersed liquid decreases and the liquid volume increases, the removal efficiency of by-product fine particles may be reduced. On the other hand, if the alkali concentration used for the pH adjustment exceeds the upper limit, it may be difficult to adjust the desired pH, which may reduce the removal efficiency of by-product fine particles.

(3-2) Removal step of by-product fine particles From the aqueous dispersion of colored resin particles containing free by-product fine particles obtained through the pH adjustment step of the above (3-1) colored resin particle re-dispersion solution, It is preferable to remove raw fine particles to obtain desired colored resin particles (wet cake) in a wet state.

  The method of removing by-product fine particles from the aqueous dispersion of colored resin particles containing liberated by-product fine particles is particularly limited as long as the by-product fine particles can be suitably removed without adversely affecting the colored resin particles. However, from the viewpoint of efficiently removing fine by-product fine particles having a so-called submicron order with a particle size of less than 0.6 μm, it is preferable to use a wet classifier that performs classification by centrifugal force.

  As a wet classifier that performs classification by centrifugal force, it is more preferable to use a decanter type centrifuge or a wet cyclone, and it is particularly preferable to use a decanter type centrifuge because it is excellent in the removal efficiency of by-product fine particles. .

An example of a method for removing by-product fine particles from an aqueous dispersion of colored resin particles containing liberated by-product fine particles using a decanter type centrifuge is shown below.
The decanter type centrifuge has a structure including an outer rotating cylinder and a screw conveyor provided in the outer rotating cylinder so as to be relatively rotatable. By rotating the outer rotating cylinder at a high speed, centrifugal force can be generated and separated into a solid content (wet colored resin particles) and a liquid content (an aqueous dispersion containing by-product fine particles). Wet colored resin particles from which raw fine particles have been suitably removed are obtained.

The centrifugal force generated by the high-speed rotation of the outer rotating cylinder is preferably 1000 to 4000G, and more preferably 1500 to 3100G.
When the centrifugal force is less than the lower limit, the separability between the solid content (wet colored resin particles) and the liquid content (an aqueous dispersion containing by-product fine particles) deteriorates, and the by-product fine particles Removal may be insufficient. On the other hand, when the centrifugal force exceeds the above upper limit, the mechanical impact on the colored resin particles is too strong, so that the colored resin particles are adversely affected such as cracking or pulverization, and desired colored resin particles are obtained. May not be possible.
In addition, what is necessary is just to set suitably the rotation speed difference of an outer side rotation cylinder and a screw conveyor, However, It is preferable that it is 1-30 rotations per minute, and it is more preferable that it is 5-20 rotations.

After removing the by-product fine particles from the aqueous dispersion of colored resin particles containing the liberated by-product fine particles, the average number of by-product fine particles per colored resin particle is preferably 40 or less, More preferably, it is 30 or less, and even more preferably 20 or less.
When the average number of by-product fine particles per one colored resin particle exceeds the above upper limit, the by-product fine particles adhering to the surface of the colored resin particles cannot be sufficiently released from the colored resin particles. In the step (4-2) dewatering step by the basket type centrifugal filter, it may cause clogging of the filter medium, which may reduce the dewatering efficiency and adversely affect the printing performance.

(3-3) Step of obtaining colored resin particle re-dispersion liquid (wet colored resin particles in a wet state in which by-product fine particles are suitably removed, obtained through the above-mentioned (3-2) by-product fine particle removal step) The wet cake is preferably redispersed to an appropriate solid content concentration using ion-exchanged water.
The appropriate solid content concentration is preferably 15 to 35% by weight, more preferably 20 to 25% by weight, and can be used in the next step (4) dehydration step.

(4) Dehydration process This process includes (4-1) an aggregation formation process of colored resin particles, and (4-2) a dehydration process using a basket-type centrifugal filter. be able to.

(4-1) Colored resin particle agglomeration forming step Acid and / or cationic polymer flocculant is added as a flocculant to the redispersed liquid of colored resin particles obtained through the above-mentioned (3) by-product fine particle removing step. By doing so, it is preferable to form an aggregate (floc) of colored resin particles.
In addition, as an aggregating agent used by this invention, when using independently, only an acid is preferable.

  By adding a flocculant to the redispersion of colored resin particles obtained through the step (3) by-product fine particle removal step, the colored resin particles that have been in the dispersed state so far become aggregated together, Flock (aggregates of colored resin particles) is formed. The aggregated state of the aggregate of the colored resin particles is not a rigid aggregated state. If the aggregate of the colored resin particles is redispersed in an aqueous medium, the aggregated state is so loose that the aggregated state is easily released (soft aggregated state) )It is in.

  Since the aggregate of the colored resin particles formed in this step is in such a soft aggregation state, when dehydrating in the dehydration step of the next step (4-2) basket type centrifugal filter, In addition, since a large number of passages (gap) through which moisture can pass are secured, dehydration is easily performed, dehydration efficiency can be improved, and wet colored resin particles (wet cake) with a low moisture content. ) Can be acquired efficiently.

The pH of the re-dispersed liquid of colored resin particles when an acid is added as a flocculant is preferably 2-6, and more preferably 4-6.
When the pH of the redispersion of the colored resin particles to which acid is added as the flocculant is less than the lower limit, the corrosion of the equipment is likely to occur due to the increased acidity of the colored resin particle aqueous dispersion. There is. On the other hand, when the pH of the re-dispersion liquid of the colored resin particles to which an acid is added as the flocculant exceeds the above upper limit, it becomes difficult to form an aggregate of the colored resin particles, and the wet state coloring with a low water content is performed. It may be difficult to obtain resin particles (wet cake).

The acid used as the flocculant is not particularly limited, and examples thereof include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid; organic acids such as formic acid and acetic acid; Among these, sulfuric acid is particularly preferably used because of its high effect as a flocculant.
In addition, although the acid used as a flocculent can also be used individually by 1 type, you may use it in combination of 2 or more type.

The acid used as the flocculant is preferably used after the concentration is adjusted to a low concentration, and the acid concentration is preferably 0.05 to 1% by weight, more preferably 0.1 to 0.5% by weight, even more preferably. Is preferably used as a flocculant whose concentration is adjusted to an aqueous solution containing 0.1 to 0.2% by weight of acid.
The amount of acid added varies depending on the acid concentration, but the amount added is particularly limited as long as the pH of the redispersion of colored resin particles after the acid is added is 2-6. Not.

  When the concentration of the acid used as the aggregating agent is less than the lower limit, a large amount of aggregating agent (acid) is required to agglomerate the colored resin particles in this step. In this step, a lot of dehydration time is required and the dehydration efficiency may be deteriorated. On the other hand, when the concentration of the acid used as the flocculant exceeds the above upper limit, it becomes difficult to adjust the pH of the redispersion of the colored resin particles to a desired pH, and aggregates of the colored resin particles are formed. It may be difficult to be done.

The cationic polymer flocculant used as the flocculant is not particularly limited as long as it is a cationic polymer flocculant having a cation moiety. For example, dimethylaminoethyl acrylate polymer flocculant (Formula 1 below) ( "DAA-based"), dimethylaminoethyl methacrylate-based polymer flocculant (following formula 2) (also referred to as "DAM-based"), and polyvinylamidine-based polymer flocculant (following formula 3) and the like. Among these, since the effect as a flocculant is high, a dimethylaminoethyl acrylate type polymer flocculant ("DAA type") is preferably used.
The cationic polymer flocculant used as the flocculant in the present invention can be used alone or in combination of two or more.

In the above formulas 1 to 3, X ⁻ is a monovalent counter anion, and halogen ions such as fluorine ion, chlorine ion, bromine ion and iodine ion, nitrate ion, bicarbonate ion, hydrogen sulfate ion, and perchloric acid Ion etc. are mentioned, Among these, halogen ion is preferable.
In the above formulas 1 to 3, m and n are numbers representing the repeating unit of the copolymer.

The addition amount of the cationic polymer flocculant used as the flocculant is preferably 0.001 to 1 part by weight, and 0.002 to 0.5 part by weight with respect to 100 parts by weight of the colored resin particles. Is more preferably 0.002 to 0.1 parts by weight.
When the addition amount of the cationic polymer flocculant is out of the above range, it is difficult to form aggregates of colored resin particles, and it is difficult to obtain wet colored resin particles (wet cake) having a low water content. There is a case.

In the colored resin particles after aggregation and obtained before the dehydration step by the basket type centrifugal filter obtained through the above-mentioned (4-1) colored resin particle aggregation step, the following step (4-2) by the basket type centrifugal filter From the viewpoint of improving the dehydration efficiency in the dehydration step, the volume average particle size (Dv ₂ ) is preferably 2.4 to 16 μm, and more preferably 3.6 to 14.4 μm. Further, the number average particle diameter (Dn ₂ ) is preferably 2 to 15 μm, and more preferably 3 to 13.5 μm.

The volume average particle size (Dv ₂ ) and the number average particle size (Dn ₂ ) are values measured using a particle size measuring device, for example, a particle size measuring device (manufactured by Beckman Coulter, Inc.) (Product name: Multisizer).

The ratio (Dn ₂ / Dn ₁ ) between the number average particle diameter (Dn ₂ ) and the number average particle diameter (Dn ₁ ) described above is preferably 1.2 to 2.0.

When the number average particle size ratio (Dn ₂ / Dn ₁ ) is less than the above lower limit, agglomerated colored resin particles are not sufficiently formed, and wet colored resin particles having a low moisture content (wet cake) ) May be difficult to obtain. On the other hand, when the number average particle diameter ratio (Dn ₂ / Dn ₁ ) exceeds the upper limit, an excessive aggregate is formed too much, and a liquid feeding pump used for liquid feeding to a basket type centrifugal filter or the like. Clogging may occur.

(4-2) Dehydration step using basket type centrifugal filter In this step, the aqueous dispersion containing the aggregated colored resin particles obtained through the above-mentioned (4-1) colored resin particle aggregation formation step is converted into a basket type centrifuge. A scraper blade is brought into contact with the wet cake layer formed on the filter cloth surface of the rotating basket and facing the rotating direction of the rotating basket to scrape the wet cake layer. By injecting pressurized gas onto the wet cake layer (residual layer) remaining on the filter cloth surface without being scraped off by the cutting blade, and peeling the residual layer, the operation efficiency of the basket-type centrifugal filter can be extended for a long time. The dehydration process can be performed while maintaining the temperature.

  FIG. 3 is a diagram schematically showing a configuration of a basket type centrifugal filter used in the present invention. The basket type centrifugal filter used in the present invention includes a rotating blade 2 and a scraping blade 3 for scraping off a wet cake layer formed on a filter cloth surface (the surface of the filter cloth 4) stretched on the inner peripheral surface of the rotating basket. The spray nozzle 9 that peels off the wet cake layer (residual layer) remaining on the filter cloth surface without being scraped off by the scraping blade 3 with the pressurized gas, the wet cake scraped off by the scraping blade 3 and the pressure A discharge chute 5 and the like for discharging the wet cake of the residual layer peeled off from the filter cloth surface by gas to the outside of the machine are mainly provided. An air knocker 10 is provided on the discharge chute 5, and an injection nozzle 9 is provided on the inner surface of the discharge chute 5.

Examples of the material of the filter cloth 4 used in the basket type centrifugal filter used in the present invention include polyester fiber, polypropylene fiber, and nylon fiber. From the viewpoint of acid resistance and alkali resistance, polyester fiber and / or polypropylene fiber are used. Preferably there is.
It is preferable from the viewpoint of productivity that the air permeability of the filter cloth is in the range of 0.2 to 1.0 cc / cm ² / second. The filter cloth preferably has a thickness in the range of 0.3 to 1.0 mm from the viewpoint of durability and productivity.

FIG. 2 is a schematic diagram for explaining the arrangement of the scraping blade and the pressurized gas injection port in the basket type centrifugal filter used in the present invention. In the present invention, from the viewpoint of suitably peeling the residual layer from the filter cloth surface, the injection angle of the pressurized gas is specified as follows.
1) As shown in FIG. 2A, the line segment connecting the point X where the scraping blade 3 is in contact with the residual layer 6 and the center point 7 of the rotation axis of the rotating basket, and the point Y where the pressurized gas hits the residual layer 6 and rotation. An angle (θ ₁ ) formed with the line connecting the center point 7 of the basket rotation axis is within a range of 270 ° to less than 360 ° with respect to the scraping direction O. Here, “within the range of 270 ° or more and less than 360 ° with respect to the scraping direction” means that the azimuth angle around the center point 7 of the rotation axis of the rotating basket is the point X at which the scraping blade 3 contacts the residual layer 6. When the azimuth angle of the line segment connecting the center point 7 of the rotation axis of the rotating basket becomes 0 ° and the value of the azimuth angle increases as it advances in the scraping direction O, the azimuth angle is 270 ° or more and 360 °. It means within the range of less than.
2) As shown in FIG. 2B, the line segment connecting the center point 8 of the injection port for injecting the pressurized gas and the point Y where the pressurized gas hits the residual layer 6 and the point where the pressurized gas hits the residual layer 6 An angle (θ ₂ ) formed with the tangent line Z is set within a range of 20 ° or more and less than 90 °. Here, “the center point 8 of the injection port” means the center point of the shape when the opening of the injection port is viewed from the front, and “tangent line Z” means the tangent of the arc of the rotating basket. .

Here, the “point where the pressurized gas hits the residual layer” means a point when the pressurized gas is injected from the injection port and reaches the residual layer. When the pressurized gas is ejected vigorously from the injection port, it reaches the residual layer in a parallel gas flow having substantially the same cross section as the opening of the injection port, and has approximately the same area as the opening of the injection port. A reaching region having a spread is formed on the surface of the residual layer. Therefore, the point located at the center in the region where the gas flow on the surface of the residual layer has reached can be specified as the “point where the pressurized gas hits the residual layer”.
In practice, it is very complicated to actually measure the point where the pressurized gas hits the residual layer or the center point of the region where the pressurized gas hits the residual layer. Therefore, in the present invention, the point where the imaginary line with the center of the opening of the injection port as the base point is extended in the injection direction of the pressurized gas design reaches the surface of the residual layer. It may be specified as “a point corresponding to

The pressurized gas injection angle (θ ₁ ) is in the range of 270 ° to less than 360 °, and preferably in the range of 315 ° to less than 360 °.
Further, the injection angle (θ ₂ ) of the pressurized gas is in the range of 20 ° or more and less than 90 °, and preferably in the range of 40 ° or more and less than 90 °.

When the injection angles (θ ₁ ) and (θ ₂ ) of the pressurized gas are out of the above range, the residual layer cannot be suitably peeled from the filter cloth surface, and the liquid passage route (gap). May become difficult to secure, the filtration resistance may increase, and the dewatering capacity per unit time may decrease.

Usually, the scraping blade is brought into contact with the wet cake layer so that the cutting edge faces the rotating direction of the rotating basket.
In this invention, it is preferable to install the injection nozzle provided with the injection port which injects pressurized gas in the back surface side of a scraping blade from a viewpoint of peeling a residual layer suitably from the filter cloth surface. Here, “the back side of the scraping blade” means the side where the residual layer meets after passing through the blade edge.

In the present invention, the pressure of the pressurized gas injected from the injection port is preferably 0.1 to 1.5 MPa, more preferably 0.2 to 1.0 MPa, and 0.3 to 0.00. More preferably, it is 8 MPa.
When the pressure of the pressurized gas is less than the lower limit, the injection impact force by the pressurized gas cannot be sufficiently obtained, and the residual layer may not be peeled off from the filter cloth surface. On the other hand, when the pressure of the pressurized gas exceeds the upper limit, the injection impact force by the pressurized gas is too strong and may damage the filter cloth.

The distance from the injection port for injecting the pressurized gas to the pressurized gas reaching the residual layer is preferably 5 to 30 mm, more preferably 7 to 15 mm, and 9 to 13 mm. More preferably.
When the distance between the jetting port and the residual layer is less than the lower limit, the jet impact force by the pressurized gas is too strong, the residual layer is likely to be scattered, and the wet cake recovery rate may be reduced. is there. On the other hand, when the distance between the injection port and the residual layer exceeds the upper limit, even if pressurized gas is injected, the injection impact force is not sufficiently obtained, and the residual layer is peeled off from the filter cloth surface. May not be possible.

The injection nozzle having the injection port for injecting the pressurized gas has a maximum installation interval of the depth of the rotating basket (that is, the width direction of the scraping blade), and is preferably installed at a number of 120 mm or less. It is more preferable to install the following number, and it is even more preferable to install the number of 80 mm or less.
When the interval at which the spray nozzle is installed exceeds the upper limit, there may be a residual layer that is not exposed to pressurized gas, and the residual layer may not be suitably peeled from the filter cloth surface.

In addition, the injection nozzles having the injection ports whose pressurized gas injection angles are (θ ₁ ) and (θ ₂ ) specified in the present invention are provided at both ends in the depth direction of the rotating basket, that is, both ends of the residual layer. Is also preferably installed.
For example, if pressurized gas is not injected only at both ends of the residual layer, the filtration resistance increases only at both ends of the residual layer, and this state may cause troubles such as abnormal vibration of the rotating basket. is there.
Examples of the pressurized gas include inert gases such as nitrogen, argon and helium, air, and the like, but air or nitrogen is preferable from the viewpoint of cost.

The moisture content of the wet cake scraped by the scraping blade and the wet cake of the residual layer peeled off from the filter cloth surface by the pressurized gas is preferably 25% by weight or less, and 20% by weight or less. Is more preferable, and it is further more preferable that it is 15 weight% or less.
When the moisture content of the wet cake exceeds the upper limit, the wet cake may adhere to the inner wall of the discharge chute and block the discharge port in the (5) discharge recovery step of the next step.

(5) Discharge / recovery process In this process, the wet cake layer scraped by the scraping blade obtained through the dehydration process by the above-mentioned (4-2) basket type centrifugal filter and peeled by the pressurized gas. When discharging the wet cake of the residual layer out of the machine through the discharge chute, before and after discharging, the wet chute is vibrated and / or by injecting pressurized gas along the inner wall of the discharge chute. However, it is possible to prevent the wet cake having a low water content from being efficiently recovered by preventing the discharge chute from adhering to the inner wall of the discharge chute.

  (4-2) When discharging the wet cake obtained in the dehydration process by the basket type centrifugal filter out of the machine through the discharge chute, the discharge port of the discharge chute is blocked, and the wet cake recovery rate is lowered. May end up. The wet cake obtained by the dehydration process of the present invention has a relatively low water content, but it contains water to some extent, so that it may adhere to the inner wall of the discharge chute, and the electric charge of the wet cake May generate an electrostatic force and adhere to the inner wall of the discharge chute.

  In the present invention, the wet cake attached to the inner wall of the discharge chute by vibrating the discharge chute and / or by injecting the pressurized gas along the inner wall of the discharge chute before and after discharging the wet cake. Even if there is, it can be removed from the inner wall, the trouble of closing the discharge port is solved, and the discharge of the wet cake can be promoted, so that the wet cake having a low water content can be efficiently recovered. .

  In the present invention, the method of vibrating the discharge chute (that is, the method of vibrating the discharge chute) is not particularly limited as long as it is a method capable of giving an impact vibration force enough to drop off the wet cake attached to the inner wall. Typical examples include a method using an impact applying device such as an air knocker that drives a piston by the force of compressed air, an electronic knocker that drives a hammer by electric power, or a piston vibrator.

  In the present invention, for example, one or more impact application devices are attached to the outer wall of the discharge chute so that the impact vibration force due to vibration is effectively applied to the wet cake attached to the inner wall of the discharge chute. Considering the inner diameter of the outlet of the discharge chute, the amount of wet cake to be discharged, and the moisture content of the discharged wet cake, etc., the position to perform vibration, the vibration timing, and the vibration interval (times / second) The wet cake adhering to the inner wall of the discharge chute can be removed from the inner wall by adjusting the etc. as appropriate and periodically giving a shock vibration by a timer or the like, and also smoothly promoting the discharge of the wet cake. it can.

In the present invention, the above-described discharge chute is also vibrated by installing a jet nozzle having an injection port for jetting pressurized gas on the inner wall of the discharge chute and jetting along the inner wall of the discharge chute. The same effect can be obtained as in the case of. By injecting the pressurized gas along the inner wall of the discharge chute, a layer of gas flow is formed along the inner wall of the discharge chute, so that the wet cake that moves in the discharge chute hardly adheres to the inner wall of the discharge chute. Become.
Furthermore, a higher effect can be obtained by combining the impact vibration force caused by the vibration and the injection impact force caused by the pressurized gas.

  In the present invention, for example, one or more injection nozzles are installed on the inner wall of the discharge chute so that the injection impact force of the pressurized gas is effectively applied to the wet cake attached to the inner wall of the discharge chute. In consideration of the inner diameter of the discharge chute outlet, the amount of wet cake to be discharged, and the moisture content of the discharged wet cake, the installation position of the ejection nozzle, the number of ejection nozzles installed, the injection timing of the pressurized gas, By appropriately adjusting the pressure of the pressurized gas (MPa), the pressurized gas injection time (seconds / times), the number of times of pressurized gas injection (times), etc., the wet cake attached to the inner wall of the discharge chute, In addition to being able to drop off from the inner wall, the discharge of the wet cake can be promoted smoothly.

In the present invention, the pressure of the pressurized gas injected from the injection port along the inner wall of the discharge chute is preferably 0.1 to 1.5 MPa, more preferably 0.2 to 1.0 MPa. More preferably, it is 0.3 to 0.8 MPa.
When the pressure of the pressurized gas is less than the lower limit, a jet impact force due to the pressurized gas cannot be obtained sufficiently, and the wet cake attached to the inner wall may not be removed. On the other hand, when the pressure of the pressurized gas exceeds the upper limit, the injection impact force of the pressurized gas is too strong, and the wet cake is likely to be scattered, which may reduce the wet cake recovery rate.

(6) Drying step The colored resin particles (wet cake) in a wet state with a low water content obtained through the above (5) discharge and recovery step are collected, and the desired colored resin particles are obtained by drying the colored resin particles. be able to.

  The method for drying the wet colored resin particles (wet cake) having a low water content obtained through the above (5) discharge and recovery step is not particularly limited, and various known methods can be used. , Vacuum drying method, air flow drying method, spray drying method, fluidized bed drying method and the like.

  The dryer used in this step is not particularly limited as long as the desired colored resin particles can be obtained, and various commercially available dryers can be used, for example, drying using a vacuum drying method. As the machine, vacuum dryer manufactured by Hosokawa Micron (trade name: Nauta Mixer), vacuum dryer manufactured by Okawara Seisakusho (trade name: Ribocorn), vacuum dryer manufactured by Shinko Environmental Solution Co., Ltd. (trade name: SV mixer) ); As dryers using the air drying method, air dryers manufactured by Hosokawa Micron (trade name: Drymaster DMR), air dryers manufactured by Seishin Enterprise (trade name: flash jet dryer); fluidized bed drying method A typical example of the dryer using the airflow is an air-bed dryer (trade name: slit flow) manufactured by Okawara Seisakusho.

According to the known drying method, when the colored resin particles (wet cake) in a wet state having a low water content obtained through the above (5) discharge / recovery step are dried, the colored resin particles that have been in an aggregated state until now are 1 The agglomerated state disintegrates until the individual colored resin particles are independent, and the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the obtained colored resin particles after drying are the same as those in (1) Colored resin. Colored resin particles having the same average particle diameter as the volume average particle diameter (Dv ₁ ) and the number average particle diameter (Dn ₁ ) of the colored resin particles obtained through the step of obtaining the particle aqueous dispersion can be obtained.

The water content of the colored resin particles obtained by drying is preferably 0.4% by weight or less, more preferably 0.3% by weight or less, and further preferably 0.2% by weight or less.
When the moisture content of the dried colored resin particles exceeds the above upper limit, image quality is liable to deteriorate due to fog and the like, and print performance such as print durability may be adversely affected.

(Colored resin particles)
The particle size characteristics of the colored resin particles obtained through the above (6) drying step will be described below.
The colored resin particles described below include both core-shell type and non-core type.

  In the colored resin particles obtained through the above (6) drying step, the volume average particle diameter (Dv) is preferably 2 to 10 μm, and preferably 3 to 9 μm, from the viewpoint of forming a high-quality image. Is more preferable. The number average particle diameter (Dn) is preferably 1.7 to 8.4 μm, more preferably 2.5 to 7.5 μm.

  When the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the colored resin particles are less than the lower limit, the fluidity of the toner is lowered, and the image quality is liable to be deteriorated due to fogging, Print performance may be adversely affected. On the other hand, when the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the colored resin particles exceed the upper limit, it is difficult to form a high-definition image, and the resolution of the obtained image is likely to be lowered. Therefore, the print performance may be adversely affected.

The particle size distribution (Dv / Dn), which is the ratio between the volume average particle size (Dv) and the number average particle size (Dn) of the colored resin particles, is 1.0 to 1. 3 is preferable, and 1.0 to 1.2 is more preferable.
When the particle size distribution (Dv / Dn) of the colored resin particles exceeds the above upper limit, the fluidity of the toner is lowered, the image quality is liable to be deteriorated due to fogging, and the printing performance may be adversely affected. is there.

  In addition, the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the colored resin particles are values measured using a particle size measuring device, for example, a particle size measuring device manufactured by Beckman Coulter, Inc. It can be measured using (trade name: Multisizer).

The average circularity of the colored resin particles is preferably 0.975 or more, more preferably 0.98 or more, and further preferably 0.985 or more from the viewpoint of forming a high-quality image. .
When the average circularity of the colored resin particles is less than the lower limit, the fine line reproducibility of toner printing tends to be lowered, and the printing performance may be adversely affected.

Here, “circularity” is defined as a value obtained by dividing the circumference of a circle having the same projected area as the particle image by the circumference of the projected image of the particle. The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of the particles, and is an index indicating the degree of unevenness of the colored resin particles. The average circularity is determined by the colored resin particles. 1 is shown in the case of a perfect sphere, and the value becomes smaller as the surface shape of the colored resin particles becomes more complicated. For the average circularity, the circularity (Ci) of each particle measured for particles having an equivalent circle diameter of 0.4 μm or more was determined for each of n particles from the following calculation formula 1, and then the average circularity was calculated from the following calculation formula 2. The degree (Ca) is obtained.
Formula 1:
Circularity (Ci) = perimeter of circle equal to projected area of particle / perimeter of projected particle image

In the above calculation formula 2, fi is the frequency of particles having a circularity (Ci).
The circularity and the average circularity can be measured using, for example, a flow type particle image analyzer “FPIA-2000”, “FPIA-2100”, “FPIA-3000” manufactured by Sysmex Corporation.

(toner)
The colored resin particles obtained in the present invention may be used as they are or as colored toner particles and carrier particles (ferrite, iron powder, etc.), but the toner's chargeability, fluidity, storage stability, etc. are adjusted. In view of the above, the colored resin particles and the external additive may be mixed using a high-speed stirrer (for example, trade name: FM mixer (manufactured by Mitsui Mining Co., Ltd.)) to form a one-component toner. After mixing the external additive, carrier particles may be further mixed to form a two-component developer.

External additives include inorganic fine particles made of silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, cerium oxide, etc .; polymethyl methacrylate resin, silicone resin, melamine resin, etc. Organic fine particles; and the like. Among these, inorganic fine particles are preferable, and among inorganic fine particles, silica and titanium oxide are preferable, and silica is particularly preferable. The above external additives can be used alone, but it is preferable to use two or more types in combination.
In the present invention, it is desirable to use the external additive in a proportion of usually 0.1 to 6 parts by weight, preferably 0.2 to 5 parts by weight with respect to 100 parts by weight of the colored resin particles.

  As described above, the method for producing a polymerized toner according to the present invention suitably separates the hardly filterable residual layer from the filter cloth surface by specifying the injection angle of the pressurized gas in the dehydration step. In the discharge recovery process, when the wet cake is discharged through the discharge chute by oscillating the discharge chute and / or injecting pressurized gas along the inner wall of the discharge chute, This is a method for producing a polymerized toner that prevents the adhering to the inner wall of the discharge chute to block the discharge port, efficiently recovers a wet cake having a low water content, and enables stable long-term operation.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited only to these examples. Parts and% are based on weight unless otherwise specified.
The test methods performed in the examples and comparative examples are as follows.

(1) Particle size characteristics of colored resin particles (1-1) Volume average particle size (Dv ₁ ) and number average particle size (Dn ₁ ) of colored resin particles before aggregation, and volume average of colored resin particles after aggregation Particle size (Dv ₂ ) and number average particle size (Dn ₂ )
About 0.1 g of a measurement sample (colored resin particles before agglomeration) is weighed and taken into a beaker, and 10 to 30 ml of an electrolyte (Beckman Coulter, trade name: Isoton II-PC) is further added to the beaker. After stirring, using a particle size measuring device (Beckman Coulter, trade name: Multisizer), aperture diameter: 100 μm, medium: Isoton II-PC, number of measured particles: 100,000 Then, the volume average particle diameter (Dv ₁ ) and the number average particle diameter (Dn ₁ ) of the colored resin particles before aggregation were measured.
Similarly, the volume average particle diameter (Dv ₂ ) and the number average particle diameter (Dn ₂ ) of the colored resin particles after aggregation were also measured.

(1-2) Volume average particle size (Dv) and number average particle size (Dn) of colored resin particles after drying, and particle size distribution (Dv / Dn)
About 0.1 g of a measurement sample (colored resin particles after drying) was weighed and taken in a beaker, and 0.1 ml of an alkylbenzenesulfonic acid aqueous solution (manufactured by Fuji Film Co., Ltd., trade name: Drywell) was added as a dispersant. To the beaker, 10-30 ml of a special electrolyte (Beckman Coulter, trade name: Isoton II-PC) was further added and dispersed for 3 minutes with a 20 W ultrasonic disperser. The volume average particle diameter of the colored resin particles after drying under the conditions of aperture diameter: 100 μm, medium: Isoton II-PC, number of measured particles: 100,000 (Dv) and the number average particle size (Dn) were measured, and the particle size distribution (Dv / Dn) was calculated.

(1-3) Average circularity of colored resin particles after drying 10 ml of ion-exchanged water is put in a container in advance, and 0.02 g of a surfactant (alkyl benzene sulfonic acid) as a dispersant is added thereto, and further colored. 0.02 g of resin particles were added, and dispersion treatment was performed at 60 W for 3 minutes using an ultrasonic disperser. The concentration of the colored resin particles at the time of measurement is adjusted to be 3,000 to 10,000 particles / μl, and 1,000 to 10,000 colored resin particles having an equivalent circle diameter of 0.4 μm or more are flow-type particle images. Measurement was performed using an analyzer (trade name: FPIA-2100, manufactured by Simex Corporation). The average circularity was determined from the measured value.
The circularity is shown in the following calculation formula 1, and the average circularity is the number average.
Formula 1:
(Circularity) = (Perimeter of circle equal to projected area of particle) / (Perimeter of particle projection image)

  Table 1 shows the results of the particle size characteristics of the colored resin particles in each of the above steps.

(2) Measurement of electrical conductivity About the filtrate obtained in the separation and washing step, the electrical conductivity of the filtrate was measured using an electrical conductivity meter (trade name: ES-12, manufactured by Horiba, Ltd.), and the following calculation was performed. The electrical conductivity of the substantial filtrate was obtained from Equation 3.
Formula 3:
Electric conductivity of the filtrate (μS / cm) = A−B
A: Electrical conductivity of measured filtrate (μS / cm)
B: Electric conductivity of ion exchange water (μS / cm)

(3) Average number of by-product fine particles 1 ml of 10% H ₂ SO ₄ was added to 3 ml of the re-dispersed colored resin particles after the separation and washing step to completely dissolve the dispersion stabilizer. 2 ml of this solution was dropped on a filter paper (manufactured by Advantech Toyo Co., Ltd., trade name: No. 2), filtered, and air-dried to prepare a sample for a scanning electron microscope (SEM).
Platinum deposition is performed on the air-dried colored resin particles, and scanning is performed using a field emission scanning electron microscope (manufactured by Hitachi, Ltd., trade name: S-4700) with an acceleration voltage of 5 kV and 5,000 times magnification. Observation with an electron microscope (SEM).
For each sample, images of 5 fields of view were randomly taken, 5 colored resin particles were randomly selected in each image, and the number of by-product fine particles observed on the surface of these 25 colored resin particles was counted. . From this, the average number of by-product fine particles per colored resin particle was calculated.
Similarly, the average number of by-product fine particles per colored resin particle was calculated for the re-dispersed liquid of the colored resin particles after the by-product fine particle removing step.

(4) Measurement of moisture content In the dehydration step using a basket type centrifugal filter, about 5 g of the formed wet cake was weighed, collected in an aluminum dish, precisely weighed (W ₁ (g)), and then 105 ° C. For 2 hours, the weight after cooling was precisely weighed (W ₂ (g)), and the moisture content (%) was determined by the following calculation formula 4.

Example 1
(Step of obtaining colored resin particle aqueous dispersion)
81 parts of styrene as monovinyl monomer and 19 parts of n-butyl acrylate (Tg of the resulting copolymer = 55 ° C.), polymethacrylate macromonomer (manufactured by Toagosei Co., Ltd., trade name: AA6) as macromonomer 0.3 parts of the resulting polymer (Tg = 94 ° C.), 0.5 parts of divinylbenzene as a crosslinkable polymerizable monomer, 1.2 parts of t-dodecyl mercaptan as a molecular weight regulator, and carbon as a black colorant 7 parts of black (trade name: # 25B, manufactured by Mitsubishi Chemical Corporation) were mixed and wet pulverized using a media type disperser.

  In the mixture obtained by the wet pulverization, 1 part of a charge control resin (manufactured by Fujikura Kasei Co., Ltd., trade name: Acrybase FCA-207P, styrene / acrylic resin) as a charge control agent, and dipentaerythritol hexamilli as a release agent 7 parts of State (manufactured by NOF Corporation, trade name: W-663) was added, mixed and dissolved to obtain a polymerizable monomer composition.

  On the other hand, at room temperature, an aqueous solution in which 15.9 parts of magnesium chloride was dissolved in 170 parts of ion-exchanged water and an aqueous solution in which 8.9 parts of sodium hydroxide were dissolved in 50 parts of ion-exchanged water were gradually added with stirring. Then, a magnesium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion was prepared.

  On the other hand, 1 part of methyl methacrylate (Tg = 105 ° C. of the resulting polymer) and 65 parts of water were finely dispersed using an ultrasonic emulsifier, and an aqueous dispersion of a polymerizable monomer for shells. Got.

  The polymerizable monomer composition was charged into the magnesium hydroxide colloid dispersion (magnesium hydroxide colloid amount 6.5 parts) at room temperature and stirred. After adding 5 parts of t-butyl peroxy-2-ethylhexanoate (Nippon Yushi Co., Ltd., trade name: Perbutyl O) as a polymerization initiator, an in-line type emulsifying disperser (trade name, manufactured by Taiheiyo Kiko Co., Ltd.) was added. : Disperse by high-speed shearing and stirring until the suspension (polymerizable monomer composition dispersion) circulates 10 times at 15,000 rpm using a milder. An object droplet was formed.

  A suspension (polymerizable monomer composition dispersion) in which droplets of the polymerizable monomer composition are dispersed is placed in a reactor equipped with a stirring blade, heated to 90 ° C., and polymerized. The reaction was started. When the polymerization conversion rate reached almost 100%, 2,2′-azobis (2-methyl-N- (2-hydroxy) as a shell polymerization initiator was added to the aqueous dispersion of the shell polymerizable monomer. (Ethyl) -propionamide) (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-086, water-soluble) 0.1 part was dissolved and added to the reactor, and the reaction was continued at 90 ° C. for 4 hours. The reaction was terminated by cooling with water to obtain a colored resin particle aqueous dispersion (pH 9.3) having a core-shell structure.

A part of the obtained colored resin particle aqueous dispersion was collected, and the volume average particle diameter (Dv ₁ ) and the number average particle diameter (Dn ₁ ) of the colored resin particles before aggregation were measured. 80 μm and 6.07 μm.

(Separation and washing process)
While stirring the above colored resin particle aqueous dispersion at room temperature until the pH of the colored resin particle aqueous dispersion becomes 6.0, a 10% dilute sulfuric acid aqueous solution (an aqueous solution containing 10% by weight of sulfuric acid) is dropped. Then, it was acid-washed and the pH was adjusted.

  The pH-adjusted colored resin particle aqueous dispersion (pH 6.0) is supplied to a continuous belt filter (manufactured by Sumitomo Heavy Industries, Ltd., trade name: Eagle filter) under the following conditions for solid-liquid separation. After forming colored resin particles (wet cake) in a wet state, about 6 times the amount of ion-exchanged water (electric conductivity: 5 μS / cm) is supplied with respect to the solid content in the colored resin particle aqueous dispersion. Then, washing was performed to obtain a wet cake.

<Separation cleaning conditions>
Supply amount of colored resin particle aqueous dispersion: 200 kg / hr
Filtration area: 1m ²
Belt speed: 0.6m / min
Degree of vacuum: 35.7-42.4 kPa
Filter medium: Plain woven polypropylene (manufactured by Nakao Filter, trade name: PP312B)
Air permeability of filter medium: 1.3 cc / sec / cm ²
Supply amount of ion exchange water: 240 kg / hr

  The wet cake obtained by the above separation and washing is redispersed in ion-exchanged water (electric conductivity: 5 μS / cm) to prepare a redispersion liquid so that the solid content concentration is 20% by weight, and a colored resin A redispersion of particles was obtained.

In addition, it was pH 8.0 when pH of the re-dispersion liquid of the obtained colored resin particle was measured. Moreover, when collecting a part of the re-dispersed liquid of colored resin particles and measuring the electrical conductivity of the filtrate obtained by filtration using a filter paper (manufactured by Advantech Toyo Co., Ltd., trade name: No. 5C), 250 μS / cm.
Further, a part of the re-dispersed liquid of the colored resin particles was collected, the number of by-product fine particles observed on the surface of the colored resin particles was counted, and the average number of by-product fine particles per colored resin particle was calculated. , 120.

(By-product fine particle removal process)
While stirring the redispersed solution (pH 8.0) of the colored resin particles at room temperature until the pH becomes 11.0, a 0.1% NaOH aqueous solution (an aqueous solution containing 0.1% by weight NaOH) The pH was adjusted, and the pH-adjusted colored resin particle redispersion liquid (pH 11.0) was dispersed to release by-product fine particles adhering to the surface of the colored resin particles from the colored resin particles.

  An aqueous dispersion (pH 11.0) of the colored resin particles containing the free by-product fine particles is supplied to a decanter centrifuge (manufactured by Sakai Kogyo Co., Ltd., trade name: PTM-006) under the following conditions. The mixture was centrifuged to remove by-product fine particles to obtain a wet cake.

<Centrifuge separation conditions>
Supply amount of aqueous dispersion of colored resin particles containing free by-product fine particles: 150 kg / hr
Centrifugal force: 2000G
Difference in rotational speed between outer rotating cylinder and screw conveyor: 10 min ⁻¹

  The wet cake obtained by removing the by-product fine particles is re-dispersed in ion-exchanged water (electric conductivity: 5 μS / cm), and the re-dispersed liquid is prepared so that the solid content concentration becomes 20% by weight. The colored resin particle redispersion liquid was obtained.

  In addition, it was pH 9.5 when pH of the re-dispersion liquid of the obtained colored resin particle was measured. Further, a part of the re-dispersed liquid of colored resin particles was collected, the number of by-product fine particles observed on the surface of the colored resin particles was counted, and the average number of by-product fine particles per colored resin particle was calculated. There were two.

(Dehydration process)
A 0.1% dilute sulfuric acid aqueous solution (an aqueous solution containing 0.1% by weight of sulfuric acid) is added as a flocculant to the colored resin particle redispersed liquid (pH 9.5), and the colored resin particle redispersed liquid is added. The pH was adjusted to 4.2 so that the colored resin particles were aggregated.

A part of the colored resin particles after aggregation was collected, and the volume average particle diameter (Dv ₂ ) and the number average particle diameter (Dn ₂ ) of the aggregated colored resin particles were measured, and each was 9.79 μm. And 7.53 μm.

  The aqueous dispersion (pH 4.2) containing the agglomerated colored resin particles is supplied to the basket-type centrifugal filter shown in FIG. 3 under the following conditions, and wet formed on the filter cloth surface for each batch. The cake layer was scraped off with the scraping blade 3, and the operation of spraying pressurized air from the spray nozzle 9 every 70 batches to peel the residual layer was repeated, and a total of 1,120 batches of centrifugal dehydration were performed.

<Centrifuge dewatering conditions for each batch>
Supply amount of aqueous dispersion containing agglomerated colored resin particles: 150 kg / batch Supply time: 90 sec / batch Type of filter media: Polyester filter cloth (manufactured by Nakao Filter, trade name: TR815C)
Air permeability of the filter medium: 0.8 cc / cm ² / sec
Filtration area: 1.35 m ²
Centrifugal force: 1600G
Centrifugal dehydration time: 240 sec / 1 batch Depth of rotating basket: 480 mm
Depth of scraping blade: 460mm

<Removal conditions for residual layer every 70 batches>
Residual layer thickness: 6 mm
Distance between spray nozzle and residual layer: 10 mm
Installation position of spray nozzle: Back side of scraping blade Number of spray nozzles installed: 7 at a 75 mm interval with the depth of the rotating basket as the maximum Pressurized air spray angle (θ ₁ ): 351 °
Pressurized air injection angle (θ ₂ ): 60 °
Injection timing of pressurized air: injected every 70th batch Pressure of pressurized air to be injected: 0.5 MPa
Pressurized air injection time: 300 seconds / once Pressurized air injection: 3 times Presence of injection at both ends of the residual layer: Existence

  A portion of the wet cake formed in the first batch and a portion of the wet cake formed in every 70 batches were sampled, and the moisture content of the wet cake in the first batch and the wet cake in every 70 batches was measured. The results are shown in Table 3.

(Discharge collection process)
The wet cake obtained by scraping the wet cake layer with the scraping blade 3 performed every batch and the wet cake obtained by peeling the residual layer with pressurized air performed every 70 batches are as follows. The air knocker 10 (manufactured by Seishin Enterprise Co., Ltd.) attached to the outer wall of the discharge chute 5 is driven as an impact applying device to vibrate the discharge chute and to inject pressurized air from the injection nozzle attached to the inner wall of the discharge chute Then, while preventing the discharge port 11 of the discharge chute from being blocked by the wet cake attached to the inner wall, the discharge of the wet cake was promoted and the wet cake discharged to the discharge chute was collected.

<Conditions for prevention of discharge port blockage>
Inner diameter of discharge chute: 240mm
Air knocker excitation timing: Before and after the wet cake formed in each batch is discharged to the discharge chute Air knocker excitation interval: 1 time / 20 seconds Number of injection nozzles installed: 5 above the center of the discharge chute , 2 on the lower side [5 jet nozzles above the center of the discharge chute]
Pressurized air injection timing: Sequentially injected from the jet nozzle on the upper side Pressure of pressurized gas injected: 0.5 MPa
Pressurized air injection time: 5 seconds / once Pressurized air injection: 2 times [Two jet nozzles below the center of the discharge chute]
Compressed air injection timing: Always Pressure of pressurized air injected: 0.5 MPa

  In addition, when the wet cake formed in the first batch and the wet cake formed every 70 batches are discharged to the discharge chute, respectively, the thickness of the wet cake attached to the inner wall of the discharge chute is measured, The results are shown in Table 3.

(Drying process)
2500 kg of the wet cake collected by the above discharge and collection process is weighed and put into a vacuum dryer (trade name: Nauter Mixer DBX-6000RWV, manufactured by Hosokawa Micron Corporation). The moisture content of the wet cake is as follows. It dried until it became 0.2 weight%, and the colored resin particle was obtained.

<Drying conditions>
Degree of vacuum: 28 Torr (3.7 kPa)
Jacket temperature: 47 ° C

  A part of the colored resin particles obtained by drying was collected, and the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the colored resin particles after drying were measured to be 6.80 μm and It was 6.07 μm.

  100 parts of the colored resin particles obtained by the above drying are subjected to a hydrophobic treatment with a cyclic silazane. Number average primary particle size: 1 part of silica fine particles with 7 nm, and a number average primary subjected to a hydrophobic treatment with amino-modified silicone oil. 1 part of silica fine particles having a particle diameter of 35 nm was added, and external addition treatment was performed by mixing and stirring using a high-speed stirrer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.) to produce a polymerized toner of Example 1. .

(Example 2)
In the peeling condition of the residual layer of Example 1, the injection angle (θ ₁ ) of pressurized air with respect to the scraping blade is changed from 351 ° to 354 °, and the injection angle (θ ₂ ) of pressurized air with respect to the residual layer is changed. The pressure of the pressurized air injected from the injection nozzle is changed from 0.5 MPa to 0.4 MPa, and the injection time of the pressurized air is changed from 300 seconds / 1 time to 250 seconds. / The polymerized toner of Example 2 was produced in the same manner as in Example 1 except that it was changed to once.

(Comparative Example 1)
In the peeling condition of the residual layer of Example 1, the installation position of the spray nozzle is changed from the back side of the scraping blade to a position independent of the scraping blade, and the jet angle of the pressurized air (θ ₁ ) with respect to the scraping blade Was changed from 351 ° to 170 °, and the injection angle (θ ₂ ) of pressurized air with respect to the residual layer was changed from 60 ° to 90 ° in the same manner as in Example 1, except that the polymerization of Comparative Example 1 was performed. A toner was produced.

(Comparative Example 2)
A polymerized toner of Comparative Example 2 was produced in the same manner as in Example 1 except that in the discharge and recovery process of Example 1, the discharge port blocking prevention operation was not performed.

(Comparative Example 3)
A polymerized toner of Comparative Example 3 was produced in the same manner as in Example 1 except that the residual layer was not peeled off in the dehydration step using the basket type centrifugal filter of Example 1.
In Comparative Example 3, when a residual layer was formed and a new wet cake layer was formed on the residual layer, the moisture content of the new wet cake layer was reduced due to a decrease in dewatering capacity. When it becomes difficult to reduce the wet cake, and only a wet cake with a high water content of 25% by weight or more can be obtained, the operation of the basket-type centrifugal filter is temporarily stopped and fixed to the filter cloth surface of the rotating basket. The remaining layer was removed manually using a knife or the like, and then the operation was resumed.

(result)
Table 1 shows the results of the particle size characteristics of the colored resin particles obtained in each example and comparative example.
Table 2 shows the conditions for the peeling operation of the residual layer and the conditions for the operation for preventing the clogging of the discharge port performed in each Example and Comparative Example.
Table 3 shows the moisture content of the wet cake formed in the dehydration process by the basket-type centrifugal filter performed in each of the examples and comparative examples, and whether or not the discharge port is blocked / the thickness of the wet cake attached to the inner wall of the discharge chute. The results are shown.

(Summary of results)
From the evaluation results described in Table 3, the following can be understood.
In the method for producing the polymerized toner of Comparative Example 1, when performing the peeling operation of the residual layer, the injection angles (θ ₁ ) and (θ ₂ ) of the pressurized air were not within the range defined in the present invention. In the dewatering process for a long time with a basket type centrifugal filter, a wet cake having a low water content could not be stably obtained, so that the discharge chute may be blocked in the discharge recovery process. I understood.

  In the method for producing the polymerized toner of Comparative Example 2, a wet cake having a relatively low water content is stably used in the dehydration process over a long period of time using a basket type centrifugal filter due to the fact that the discharge port is not blocked. In the discharge recovery process, it was found that the wet cake attached to the inner wall of the discharge chute could not be removed from the inner wall, and the discharge port of the discharge chute could be blocked. .

  In the method for producing the polymerized toner of Comparative Example 3, a wet cake having a low water content can be stably obtained in the dehydration process over a long period of time using a basket type centrifugal filter due to the fact that the peeling operation of the residual layer was not performed. Therefore, it has been found that the discharge port of the discharge chute may be blocked in the discharge recovery process.

  On the other hand, in the method for producing the polymerized toner of Examples 1 and 2, the basket-type centrifugal filter was used because the residual layer peeling operation and the discharge port blocking prevention operation defined in the present invention were performed. It has been found that a wet cake having a low water content can be stably obtained in the dehydration process over a long period of time, and the discharge port of the discharge chute can be prevented from being blocked in the discharge recovery process.

DESCRIPTION OF SYMBOLS 1 ... To-be-processed liquid supply pipe 2 ... Rotary basket 3 ... Scraping blade 4 ... Filter cloth 5 ... Discharge chute 6 ... Residual layer 7 ... Center point of the rotating shaft of a rotating basket 8 ... Center of injection port which injects pressurized gas Point 9 ... Injection nozzle 10 ... Air knocker 11 ... Discharge port of discharge chute X ... Point where scraping blade contacts residual layer Y ... Point where pressurized gas hits residual layer Z ... Tangent line at point where pressurized gas hits residual layer O ... Circumference direction of scraping blade P ... Circumference direction of rotating basket

Claims (3)

Forming colored resin particles by a polymerization method to obtain an aqueous dispersion of colored resin particles,
A separation washing step for separating and washing the colored resin particles in the colored resin particle aqueous dispersion,
The separated washed colored resin particles, rotating basket, scraper blades adjacent to the filter cloth surface, first and second pressurized gas injection port, and a basket-type centrifuge having a discharge chute with a cloth surface A dehydration step of dewatering using a filter to form a wet colored resin particle (wet cake) layer in the centrifugal filter;
A discharge and recovery step of discharging and recovering the wet cake layer formed on the filter cloth surface of the rotating basket by scraping with the scraping blade and dropping it onto the discharge chute; and
A method for producing a polymerized toner including a drying step of drying the discharged and collected wet cake,
In the dehydration step, the wet cake layer formed on the filter cloth surface of the rotating basket, the rotating direction opposite to the direction of the rotating basket against the scraper blade is brought scraped the wet cake layer, those該掻In peeling off the residual layer by spraying pressurized gas onto the wet cake layer (residual layer) remaining on the filter cloth surface without being scraped off by the cutting blade,
1) A line segment connecting the point at which the scraping blade contacts the residual layer and the center point of the rotating shaft of the rotating basket, with the scraping blade and the first pressurized gas injection port disposed above the discharge chute. And an angle (θ ₁ ) formed by a line connecting the point where the pressurized gas injected from the first pressurized gas injection port hits the residual layer and the center point of the rotation axis of the rotating basket is a scraping direction. In the range of 270 ° to less than 360 °,
2) An angle (θ ₂ ) between a line segment connecting the center point of the first pressurized gas injection port and a point where the pressurized gas hits the residual layer and a tangent at the point where the pressurized gas hits the residual layer is , In the range of 20 ° or more and less than 90 °,
In the discharge and recovery process, in discharging and collecting the wet cake obtained through the dehydration process to the outside through the discharge chute,
3) Before and after discharging the wet cake, the discharge chute is vibrated and / or the pressurized gas is injected along the inner wall of the discharge chute from the second pressurized gas injection port provided on the inner wall of the discharge chute. And a method for producing a polymerized toner. An injection nozzle having the first pressurized gas injection port is installed on the back surface side of the scraping blade, and the pressure of the pressurized gas injected from the injection port is 0.1 to 1.5 MPa. The method for producing a polymerized toner according to claim 1. In the dehydration step, after aggregating the colored resin particles in the colored resin particle aqueous dispersion, dewatering using a basket type centrifugal filter,
The number average particle diameter (Dn ₂ ) of the colored resin particles after the aggregation and before the dehydration step by the basket type centrifugal filter, and the number of the colored resin particles after the step of obtaining the colored resin particle aqueous dispersion and before the separation washing step 3. The method for producing a polymerized toner according to claim 1, wherein a ratio (Dn ₂ / Dn ₁ ) to the average particle diameter (Dn ₁ ) is 1.2 to 2.0.

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