JP2007010928A - Method for manufacturing polymerized toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polymerized toner which contains very few small-particle-size colored polymer particles generated during polymerization, and which has high resolution, causes neither filming nor fogging and excels in printing durability even if long-term repetitive printing is performed. <P>SOLUTION: In the method for manufacturing the polymerized toner including a classification step of classifying colored polymer particles so that a predetermined particle size distribution is provided, an aqueous medium dispersion containing the colored polymer particles and having a solid concentration adjusted to a range of 5-30 wt.% is supplied to a wet classifier in which classification is carried out by centrifugal force, and the aqueous medium dispersion is subjected to classification under the conditions of centrifugal force in a range of 1,000-3,000 G and a ratio L/V in a range of 8-32.5, wherein L is the rate (m<SP>3</SP>/h) of supply of the aqueous medium dispersion containing the colored polymer particles to the wet classifier; and V is the volume (m<SP>3</SP>) of the wet classifier. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention may be referred to as an electrostatic latent image developing toner (hereinafter simply referred to as “toner”) used for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing, and the like. In particular, the present invention relates to a method for producing a polymerized toner having a sharp particle size distribution.

In electrophotography, an electrostatic latent image formed on a photoreceptor is developed with a toner in which other particles such as an external additive and a carrier are blended with colored particles as necessary, such as paper or an OHP sheet. After the toner is transferred to the recording medium, the transferred toner is fixed to the recording medium to obtain a printed matter. Various methods have been conventionally proposed as a method of developing with toner or a method of fixing a toner image, and methods suitable for the respective image forming methods are employed.
In recent years, there has been a growing need for colorization of image forming apparatuses such as multifunction machines, facsimiles, and printers using electrophotography. In color printing, an image that is required to reproduce a high-resolution and clear color tone such as a photograph is also printed. Therefore, a color toner that can cope with the printing is demanded.
Also, for such toners, environmental stability from the viewpoint of preventing image quality deterioration due to environmental changes such as temperature and humidity, printing durability from the viewpoint of reducing printing costs, and low temperatures from the viewpoint of reducing power consumption. Various characteristics such as fixing properties are required.

  In order to increase the resolution from the viewpoint of toner, it is possible to achieve both good transferability and dot reproducibility, and therefore, a spherical toner with a small particle size is suitable. As such a toner, a toner manufactured by polymerizing a polymerizable monomer composition containing a colorant and a polymerizable monomer (hereinafter, such a manufacturing method is referred to as a polymerization method, and a toner obtained by the method is used as a toner). Has been proposed). In the conventional pulverization method, the produced toner has a wide particle shape distribution, and the production efficiency is poor from the viewpoint of cost and energy consumption, and the yield is remarkably lowered particularly when a toner having a small particle diameter is produced. However, since the polymerization method can easily produce a spherical toner and can sharpen the particle size distribution, it can meet the above-mentioned demand for higher resolution.

  The suspension polymerization method is the mainstream in the toner production method by the polymerization method. In the suspension polymerization method, first, a polymerizable monomer, a colorant, and other additives as necessary are mixed to obtain a polymerizable monomer composition, which is an aqueous system having a dispersion stabilizer. Disperse in the medium. Next, droplets of the polymerizable monomer composition are formed by applying a high share to the aqueous medium in which the polymerizable monomer composition is dispersed using a high-speed stirrer or the like. Thereafter, an aqueous medium in which the polymerizable monomer composition formed in droplets is dispersed is polymerized in the presence of a polymerization initiator, and filtered through a filter material, washed, and dried to obtain colored polymer particles. Further, the colored polymer particles are mixed with an external additive such as a carrier or inorganic fine particles to obtain a polymerized toner.

  As described above, when colored polymer particles are formed by a polymerization method, compared to the pulverization method, the particle formation step (in the polymerization method, droplet formation and polymerization are performed, while in the pulverization method, pulverization is performed. The particle size distribution can be adjusted more sharply at the stage). However, in order to obtain high resolution and high image quality, even when using a polymerization method, fine particles that fall outside the target particle size range from the colored polymer particles obtained in the polymerization step are further removed. It is desired to be removed.

  Patent Document 1 relates to a method for removing fine powder applied to the production of a polymerized toner. A liquid dispersion of powder containing fine powder is allowed to stand, and precipitate separation (decane) is performed so that fine powder and powder having a particle size larger than that are obtained. The method for removing fine powder in a powder dispersed in a liquid is disclosed, in which the liquid layer containing the fine powder is removed.

  In Patent Document 2, a polymerizable monomer composition containing at least a colorant and a polymerizable monomer is polymerized in an aqueous dispersion medium to produce colored polymer particles, and in the aqueous dispersion medium. In the method for producing a polymerized toner comprising the step 2 of separating the colored polymer particles from the polymer toner, the separation of the colored polymer particles from the aqueous dispersion medium in the step 2 is performed using a vertical screw centrifuge. The manufacturing method is disclosed, and the separation conditions include a centrifugal force of 1500 to 3000 G, a rotational speed difference between the outer rotating cylinder and the screw conveyor of 0.1 to 5 rpm, and the like.

  In Patent Document 3, at least resin fine particles and colorant particles are fused in an aqueous medium to form colored particles, and the colored particles are separated from the aqueous medium and dried for electrostatic latent image development by an emulsion aggregation method. In the method for producing a toner, the colored particles are separated from the aqueous medium by a decanter type centrifuge having an outer rotary cylinder and a screw conveyor provided relatively rotatably in the outer rotary cylinder. A method for producing a toner for developing an electrostatic latent image is disclosed.

However, in the decantation in which the dispersion liquid is allowed to stand as disclosed in Patent Document 1, it takes a long time to remove the small particle size fine particles. It cannot be removed.
In addition, decantation using centrifugal force as disclosed in Patent Document 2 or Patent Document 3 can remove unnecessary small particle size particles in a shorter time than decantation by standing, but is disclosed in these documents. Under the separation conditions, particles in the required particle size range are likely to be mixed into the effluent together with unnecessary small particle size particles, so the recovery rate of particles in the required particle size range cannot be said to be good.

The unnecessary small particle size fine particles contained in the polymerized toner are mainly fine particles having a particle size of less than 0.6 μm in the so-called submicron order and containing no colorant (hereinafter referred to as “fine resin particles”). ) And colored polymer particles (hereinafter also referred to as “small particle colored polymer particles”) having a particle size of about 0.6 μm to 5 μm. These two are presumed to have different production processes, but cause a special problem because of their small particle size (hereinafter, both are referred to as “small particle size fine particles”).
For example, when the colored polymer particles are dehydrated from the aqueous medium, a part of such fine particles having a small particle size is clogged in the filter material, and the filtration rate is lowered or the dehydration is insufficient. Wake up.
Furthermore, since the small particle size fine particles have a large adhesive force, when a large number of sheets are printed using a polymer toner containing a large amount of such small particle size fine particles, the small particle size fine particles adhere to the members in the developing machine. Gradually accumulate and filming (adhering). When filming is performed on the developing blade or a seal member between the developing roll and the toner container, a uniform toner layer cannot be formed on the developing roll, and white lines are likely to occur in the image. When filming is performed on a developing roll or a photoreceptor, fogging occurs on a recording medium such as paper, resulting in a decrease in toner durability.

In recent years, as the level of demand for high resolution and high image quality increases, there is an increasing tendency to make the toner particle size smaller. According to the polymerization method, for example, colored polymer particles having a small particle diameter of about 3 to 15 μm can be easily formed.
However, the closer the target particle size range is to the smaller particle size side, the closer to the particle size of the small particle size as described above. Separation becomes difficult.
In particular, small-sized colored polymer particles having a particle size of about 0.6 μm to 5 μm are closer to the target particle size range of the colored polymer particles than fine resin particles. When the target particle size range is shifted to the small particle size side, the ratio of the small particle colored polymer particles is further increased, so that separation becomes very difficult and disclosed in Patent Documents 1 to 3 as described above. In the separation method or separation condition, the separation accuracy and the recovery rate of the colored polymer particles in the target particle size range are very poor.
The separation method disclosed in Patent Document 1 does not particularly distinguish between small-sized colored polymer particles having a particle size of about 0.6 μm to 5 μm and fine resin particles having a particle size of submicron order. The separation method disclosed in Patent Document 2 is intended to remove fine resin particles on the order of submicrons. The separation method disclosed in Patent Document 3 is intended to remove resin fine particles (about 0.1 μm) that have not aggregated. Therefore, these patent documents do not describe a method suitable for removing small colored polymer particles having a particle size of about 0.6 μm to 5 μm.

JP 2002-28527 A JP 2004-133326 A JP 2003-131426 A

A first object of the present invention is to provide a method for producing a polymerized toner that efficiently sharpens the particle size distribution of colored polymer particles obtained by a polymerization method by classification treatment.
The second object of the present invention is to remove small-sized colored polymer particles in a short time from colored polymer particles obtained by the polymerization method, and to classify colored polymer particles having a desired particle size range, and The present invention provides a method for producing a polymerized toner having a high recovery rate.
In addition, the third object of the present invention is when the desired particle size range of the colored polymer particles obtained by the polymerization method is shifted to the small particle size side and approaches the particle size of the small colored polymer particles. Even so, the present invention provides a method for producing a polymerized toner that removes unnecessary small colored polymer particles in a short time and has high classification accuracy and recovery rate of colored polymer particles in a required particle size range. It is to be.

The inventors of the present invention have intensively studied to achieve the above object, and using a wet classifier that performs classification by centrifugal force having a specific structure, the solid content concentration of the aqueous medium dispersion, the aqueous medium per unit volume The knowledge that the said objective can be achieved was obtained by performing a classification process by making the supply speed | rate of a dispersion liquid, etc. into specific conditions.
That is, in the method for producing a polymerized toner of the present invention, colored polymer particles are obtained by polymerizing a polymerizable monomer composition containing a polymerizable monomer and a colorant in a state of being dispersed in an aqueous medium. A polymerization step for obtaining, a washing step for washing the colored polymer particles, and a classification step for classifying the colored polymer particles to have a predetermined particle size distribution,
In the classification step, the aqueous medium dispersion containing the colored polymer particles is supplied to a wet classification apparatus that performs classification by centrifugal force, and classification is performed under the following conditions (1), (2), and (3). It is the method characterized by this.
(1) The solid content concentration of the aqueous medium dispersion supplied to the wet classifier is in the range of 5 to 30% by weight.
(2) The centrifugal force of the wet classifier is in the range of 1,000 to 3,000 G.
(3) The ratio L / V of the supply rate L (m ³ / h) of the aqueous medium dispersion to the wet classifier to the volume V (m ³ ) of the wet classifier is in the range of 8 to 32.5. .

  According to the production method of the present invention, small colored polymer particles are removed from the colored polymer particles obtained by the polymerization method, and the particle size distribution of the colored polymer particles is efficiently sharpened by classification treatment. can do. Moreover, the classification process can be performed in a short time, and the classification accuracy and recovery rate of the colored polymer particles in the required particle size range are high.

The production method of the present invention is a case where the target particle size range of the colored polymer particles obtained by the polymerization method is shifted to the small particle size side and approaches the particle size of the small particle size colored polymer particles. However, the small colored polymer particles are removed in a short time, and the recovery rate of the colored polymer particles in the required particle size range is high.
Specifically, the volume average particle size (Dv) of the colored polymer particles before classification is 6 to 8 μm, and the particle size range 0.6 to 5.0 μm in the total particle size range 0.6 to 30 μm. The volume average particle diameter (Dv) of the colored polymer particles recovered after the classification step of the colored polymer particles having a number frequency of 31 to 40% is almost the same as the above range, and the total particle diameter range is 0.6 to 30 μm. The number frequency in the particle size range of 0.6 to 5.0 μm can be 20 to 30%.
More preferably, the volume average particle size (Dv) of the colored polymer particles before classification treatment is 6 to 8 μm, and the particle size range is 0.6 to 5.0 μm in the total particle size range 0.6 to 30 μm. Volume average particles of colored polymer particles recovered after the classification step of colored polymer particles having a number frequency of 31 to 40% and a number frequency of 9 to 15% in a particle size range of 0.6 to 3.0 μm The diameter (Dv) hardly changes, the number frequency of the particle size range 0.6 to 5.0 μm in the total particle size range 0.6 to 30 μm is 20 to 30%, and the particle size range 0.6 to 3.0 μm. The number frequency can be 4 to 8%.

  As an embodiment belonging to the present invention, the classification step includes an aqueous medium containing the colored polymer particles obtained in the polymerization step, or an aqueous medium supplemented with an aqueous medium containing the colored polymer particles. It is carried out following the polymerization step by supplying it to the wet classifier as a dispersion, or a water-based medium dispersion obtained by adding an aqueous medium to the colored polymer particles obtained in the washing step to the wet classifier By supplying, the cleaning process may be continued.

  The wet classifier is preferably a wet cyclone or a decanter centrifuge. By using these apparatuses, it is possible to maintain separation performance while maintaining productivity even in a system having a high solid content concentration.

  In the method for producing a polymerized toner of the present invention, the polymerization of the polymerizable monomer composition is preferably performed by a suspension polymerization method.

  According to the production method of the present invention, classification processing of colored polymer particles having a necessary particle size range can be performed with high accuracy, high recovery rate, and in a short time. As a result, it is possible to stably and efficiently produce a polymerized toner having high resolution and excellent film durability without causing filming or fogging even when performing durable printing.

The method for producing a polymerized toner of the present invention includes a polymerization step of obtaining colored polymer particles by polymerizing a polymerizable monomer composition containing a polymerizable monomer and a colorant in a state of being dispersed in an aqueous medium. A washing step for washing the colored polymer particles, and a classification step for classifying the colored polymer particles to have a predetermined particle size distribution,
In the classification step, the aqueous medium dispersion containing the colored polymer particles is supplied to a wet classification apparatus that performs classification by centrifugal force, and classification is performed under the following conditions (1), (2), and (3). It is characterized by this.
(1) The solid content concentration of the aqueous medium dispersion supplied to the wet classifier is in the range of 5 to 30% by weight.
(2) The centrifugal force of the wet classifier is in the range of 1,000 to 3,000 G.
(3) The ratio L / V of the supply rate L (m ³ / h) of the aqueous medium dispersion to the wet classifier to the volume V (m ³ ) of the wet classifier is in the range of 8 to 32.5. .

  The outline of the method for producing a polymerized toner of the present invention is as follows. First, a polymerizable monomer composition containing a polymerizable monomer and a colorant as essential components is prepared, and the resulting polymerizable monomer composition is converted into an aqueous system. Colored polymer particles are obtained by polymerization in a state dispersed in a medium. Next, the colored polymer particles obtained in the polymerization step are classified after being washed, or washed after being classified. Next, the colored polymer particles having been subjected to washing and classification in any order are dehydrated and dried. The colored polymer particles having the particle size distribution adjusted in this way may be used as a polymerized toner as they are, but if necessary, they are mixed with other additive components to obtain a polymerized toner.

Examples of the polymerization method of the polymerizable monomer composition include a suspension polymerization method and an emulsion polymerization method. In the method for producing a polymerized toner provided by the present invention, polymerization is performed by a suspension polymerization method. It is preferable.
Hereinafter, each procedure will be described in order by taking a suspension polymerization method in the polymerization step and using a decanter centrifuge in the classification step as an example.

(1) Preparation step of polymerizable monomer composition First, a polymerizable monomer, a colorant, and, if necessary, a charge control agent and other additives are mixed to prepare a polymerizable monomer composition. To do. The colorant and other additives are preferably mixed so that they are dissolved in the polymerizable monomer or dispersed as uniformly and finely as possible. In order to perform such mixing, it is preferable to use a media type disperser.

In the present invention, the polymerizable monomer refers to a polymerizable compound.
It is preferable to use a monovinyl monomer 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; acrylonitrile Derivatives of acrylic acid such as methacrylonitrile, acrylamide and methacrylamide, and derivatives of methacrylic acid; olefins such as ethylene, propylene and butylene; vinyl chloride and vinylidene chloride And vinyl halides such as vinyl fluoride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone and methyl isopropenyl ketone. Nitrogen-containing vinyl compounds such as 2-vinylpyridine, 4-vinylpyridine, and N-vinylpyrrolidone; These monovinyl monomers may be used alone or in combination. Of these, styrene, styrene derivatives, and acrylic acid or methacrylic acid derivatives are preferably used as monovinyl monomers.

In order to improve hot offset, it is preferable to use any crosslinkable polymerizable monomer together with the monovinyl monomer. A crosslinkable polymerizable monomer means a monomer having two or more polymerizable functional groups. Examples of the crosslinkable polymerizable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; diacrylate compounds such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; N, N-divinyl. Other divinyl compounds such as aniline and divinyl ether; compounds having three or more vinyl groups; These crosslinkable polymerizable monomers can 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.

Furthermore, it is preferable to use a macromonomer as a part of the polymerizable monomer because the balance between the storage stability and the fixing property at a low temperature is improved. The macromonomer has a polymerizable carbon-carbon unsaturated double bond at the end of the molecular chain, and is a reactive oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000.
The macromonomer is preferably one that gives a polymer having a higher Tg than the Tg of the polymer obtained by polymerizing the monovinyl monomer. The amount of the macromonomer is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, and more preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the monovinyl monomer.

  In the present invention, a colorant is used. However, when 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, and a yellow toner are used. A colorant and a magenta colorant can be used, respectively.

  In the present invention, as the black colorant, carbon black, titanium black, and pigments such as magnetic powder such as iron oxide zinc and iron oxide nickel can be used.

  As the cyan colorant, for example, a copper phthalocyanine compound, a derivative thereof, and an anthraquinone compound can be used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17, 17: 1 and 60, etc. Is stable and has coloring power. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 17: 1, and the like, preferably copper phthalocyanine compounds such as C.I. I. Pigment Blue 15: 3 is more preferable.

  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, 12, 13, 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. Pigment Violet 19 etc. are mentioned. Since the polymerization stability is good and there is coloring power, C.I. I. Pigment Red 31, 48, 57: 1, 58, 60, 63, 64, 68, 112, 114, 146, 150, 163, 170, 185, 187 Monoazo pigments such as No. 206 and No. 207 are also preferred.

  The amount of each colorant added is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the monovinyl monomer.

As the charge control agent, various positively chargeable or negatively chargeable charge control agents can be used. For example, a metal complex of an organic compound having a carboxyl group or a nitrogen-containing group, a metal-containing dye, and a non-resin charge control agent such as nigrosine; a quaternary ammonium (salt) group-containing copolymer, a sulfonic acid (salt) group-containing copolymer A charge control resin such as a polymer and a carboxylic acid (salt) group-containing copolymer can be used. Among them, the charge control agent preferably contains a charge control resin because the printing durability of the toner becomes good. Of the charge control agents, a charge control agent that is not a resin and a charge control resin may be used in combination, or the charge control resin may be used alone. More preferably, the charge control resin is used alone. It is more preferable to use a quaternary ammonium group or quaternary base-containing copolymer, or a sulfonic acid group or sulfonate group-containing copolymer as the charge control resin.
The charge control agent is usually used in a proportion of 0.01 to 10 parts by weight, preferably 0.03 to 8 parts by weight, with respect to 100 parts by weight of the monovinyl monomer.

  It is preferable to use a molecular weight modifier as another additive. Examples of molecular weight modifiers include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2,4,6,6-pentamethylheptane-4-thiol. The molecular weight modifier can be added before the start of polymerization or during the polymerization. The amount of the molecular weight modifier is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the monovinyl monomer.

  Further, as other additives, it is preferable to add a release agent since the releasability of the toner from the fixing roll during fixing can be improved.

  The release agent is not particularly limited as long as it is generally used as a toner release agent. For example, low molecular weight polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; low molecular weight oxidized low molecular weight polypropylene, low molecular weight terminal-modified polypropylene having molecular ends substituted with epoxy groups, and these and low molecular weight polyethylene End-modified polyolefin waxes such as block polymers, low molecular weight oxidized low molecular weight polyethylene, low molecular weight polyethylene with molecular ends substituted with epoxy groups, and block polymers of these and low molecular weight polypropylene; candelilla, carnauba, rice, wood wax, and Plant-based natural waxes such as jojoba; petroleum-based waxes such as paraffin, microcrystalline, and petrolactam, and modified waxes thereof; minerals such as montan, ceresin, and ozokerite Synthetic waxes such as Fischer-Tropsch wax; Pentaerythritol esters such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, pentaerythritol tetrastearate, and pentaerythritol tetralaurate, dipentaerythritol hexamyristate, dipentaerythritol And polyhydric alcohol esterified products such as dipentaerythritol esters such as hexapalmitate and dipentaerythritol hexalaurate. These may be used individually by 1 type and may be used in combination of 2 or more type.

Among the above mold release agents, the endothermic peak temperature is 30 to 150 ° C., preferably 50 to 120 ° C., more preferably 60 to 100 ° C. measured from the DSC curve at the time of temperature rise using a differential scanning calorimeter. A polyhydric alcohol esterified product such as pentaerythritol ester in the range and dipentaerythritol ester having the same endothermic peak temperature in the range of 50 to 80 ° C. is particularly preferable in terms of fixing-peeling balance.
The release agent is preferably used in an amount of 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the monovinyl monomer.

(2) Droplet formation step In the present invention, the polymerizable monomer composition obtained as described above is dispersed in an aqueous medium containing a dispersion stabilizer, and after adding a polymerization initiator, Formation of droplets of the polymerizable monomer composition is performed. The method of forming the droplet is not particularly limited. For example, an in-line type emulsifier / disperser (trade name “Ebara Milder” manufactured by Ebara Seisakusho), a high-speed emulsifier / disperser (trade name “T. .. Homomixer MARK type II)) etc.

  In the present invention, the aqueous medium may be water alone, but a solvent that is soluble in water may be used in combination. Examples of the solvent that can be dissolved in water include lower alcohols such as methanol, ethanol, and isopropanol, and lower ketones such as dimethylformamide, tetrahydrofuran, acetone, and methyl ethyl ketone.

In the present invention, the aqueous medium preferably contains a dispersion stabilizer. Dispersion stabilizers include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide Metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; inorganic compounds that are soluble in acids or alkalis such as metal compounds. Furthermore, organic polymer compounds such as water-soluble polymers such as polyvinyl alcohol, methyl cellulose, and gelatin; anionic surfactants; nonionic surfactants; amphoteric surfactants; The said dispersion stabilizer can be used 1 type or in combination of 2 or more types.
Among the above dispersion stabilizers, dispersion stabilizers containing colloids of metal compounds, particularly poorly water-soluble metal hydroxides, can narrow the particle size distribution of the colored polymer particles, and can be dispersed after washing. Since the remaining amount of the stabilizer is small, the obtained polymerized toner is preferable because the image can be clearly reproduced and the environmental stability is not deteriorated.
The dispersion stabilizer is used in an amount of 0.1 to 20 parts, preferably 0.2 to 10 parts, based on 100 parts of the aqueous medium.

In the present invention, examples of the polymerization initiator for polymerizing the polymerizable monomer composition include 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-dimethyl) Valeronitrile) and azo compounds such as 2,2′-azobisisobutyronitrile; di-t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylper Oxy-2-ethylhexanoate, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, di-t-butylperoxy Examples thereof include peroxides such as phthalate and t-butylperoxyisobutyrate, etc. Further, a redox initiator in which the above polymerization initiator and a reducing agent are combined may be used. It is preferable to use a peroxide because the monomer can be reduced and the printing durability is good.
As described above, the polymerization initiator may be added after the polymerizable monomer composition is dispersed in the aqueous medium and before droplet formation, but is added to the polymerizable monomer composition. May be.
The addition amount of the polymerization initiator used for polymerization of the polymerizable monomer composition is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 100 parts by weight of the monovinyl monomer. -15 parts by weight, most preferably 1.0-10 parts by weight.

(3) Polymerization step The aqueous medium containing droplets of the polymerizable monomer composition obtained in the droplet formation step as described above is heated to initiate polymerization. The polymerization temperature of the polymerizable monomer composition is preferably 50 ° C. or higher, more preferably 60 to 95 ° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.
In addition, in order to perform the polymerization in a state where the droplets are stably dispersed, the polymerization reaction may be performed while continuing a dispersion process for forming or stabilizing the droplets in the polymerization step.

  The colored polymer particles may be used as polymerized toners as they are and with the addition of external additives. However, the colored polymer particles are obtained by using the colored polymer particles as a core layer and forming a shell layer different from the core layer on the outside. The so-called core-shell type (or “capsule type”) colored polymer particles are preferable. Core-shell type colored polymer particles balance the balance between lowering the fixing temperature and preventing aggregation during storage by coating the core layer made of a material with a low softening point with a material having a higher softening point. be able to.

  There is no restriction | limiting in particular as a method of manufacturing the said core-shell type colored polymer 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 polymer particles by in situ polymerization will be described below.
In the aqueous medium in which the colored polymer particles are dispersed, a polymerizable monomer (shell polymerizable monomer) for forming a shell layer and a polymerization initiator are added and polymerized to form a core-shell type. Colored polymer particles can be obtained.

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

  Polymerization initiators used for polymerization of the polymerizable monomer for shell include potassium persulfate and persulfate metal salts such as ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) Water-soluble polymerization initiation such as propionamide) and azo initiators such as 2,2′-azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide); An agent can be mentioned. The amount of the polymerization initiator is preferably 0.1 to 30 parts by weight, 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, more preferably 60 to 95 ° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

(4) Washing step In the present invention, the aqueous dispersion of colored polymer particles obtained by the polymerization step is usually washed by the washing step. The cleaning step in the present invention includes an acid cleaning step and a water cleaning step subsequent to the following. The water washing process can be repeated several times.

(4-1) Acid Washing Step When the aqueous dispersion of colored polymer particles obtained by polymerization uses an inorganic compound such as an acid-soluble inorganic hydroxide as a dispersion stabilizer, colored polymer particles The dispersion stabilizer is dissolved in water and removed by adding an acid to the aqueous dispersion. In addition, when a dispersion stabilizer is an inorganic compound soluble in an alkali, an alkali is used instead of an acid.

  When an acid-soluble material is used as the dispersion stabilizer, it is preferable to add an acid so that the pH of the aqueous dispersion of colored polymer particles is 6.5 or lower. More preferably, the pH is 6 or less. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as formic acid and acetic acid can be used. Particularly, since the removal efficiency is large and the burden on the manufacturing equipment is small, Sulfuric acid is preferred.

(4-2) Water washing step In the water washing step, the aqueous dispersion obtained in the acid washing step is first filtered and then washed with water by a washing device. Various known cleaning devices can be used as the cleaning device, but it is preferable to use any one or a combination of a belt filter, a rotary filter, and a filter press. More preferably, a belt filter or a rotary filter is used.

  The belt filter has a structure in which a filter medium is disposed on a drain screw belt, and a vacuum pan is installed below the drain screw belt via a slide plate having excellent wear resistance. The aqueous dispersion is supplied onto the filter medium from the upper part of the filtration surface, and is filtered and dehydrated by vacuum action. The filtrate is collected in a vacuum pan and sent to the vacuum tank from the filtrate tube. The filtered cake and the filter medium travel together with the drain screw belt, and during that time, washing water is sprinkled from above, and the soluble substances in the cake are discharged together with the filtrate. The dehydrated cake is peeled from the filter medium by a discharge roll.

(5) Classifying step In the present invention, in order to remove particles outside the target particle size range from the colored polymer particles obtained in the polymerization step, the wet polymerizing device that classifies by centrifugal force is used to add the colored polymer particles. An aqueous medium dispersion is supplied to perform classification treatment.
The aqueous medium dispersion supplied to the wet classifier may be the aqueous medium itself containing the colored polymer particles obtained in the polymerization step, or the aqueous medium containing the colored polymer particles as necessary. Further, an aqueous medium may be replenished. Alternatively, after removing part or all of the aqueous medium from the aqueous medium containing the colored polymer particles obtained in the polymerization step, an aqueous medium of the same or different type as the aqueous medium used in the polymerization is replenished as necessary. It may be what you did.

As an example of a typical procedure, a classification step is subsequently performed after completion of the polymerization step, and the aqueous medium containing the colored polymer particles obtained in the polymerization step is used as it is or further as necessary. After replenishment and adjusting to a desired solid content concentration, it is supplied to a wet classifier and classified. Alternatively, as another typical procedure, the aforementioned washing step is performed after the polymerization step, followed by the classification step, and the colored polymer particles obtained in the washing step are newly supplemented with an aqueous medium. The solid content concentration is adjusted and then supplied to a wet classifier to perform classification.
The aqueous medium for preparing the aqueous medium dispersion for classification can be the same as the aqueous medium in which the droplets of the polymerizable monomer composition are dispersed for polymerization. Is preferably ion-exchanged water, more preferably ion-exchanged water having an electric conductivity of 1 μS / cm or less.

  By performing wet classification using a wet classifier using centrifugal force, particles that are smaller than the target particle size range are removed, and the particle size distribution of the colored polymer particles is sharpened. Can do. Further, among the small-sized colored polymer particles, those having a particle size of about 1 μm, more typically 0.6 to 5 μm are particularly likely to adhere to and accumulate on members in the developing machine. As a result, white streaks on the printing surface are generated. However, the present invention has a very high effect of removing small-sized colored polymer particles having a particle diameter of about 1 μm, which is a major cause of printing durability.

  The classification step is preferably performed at least once. For example, the classification step may be performed twice or more after the polymerization step and / or after the washing step. In that case, after completion of the first wet classification, the aqueous medium dispersion of the classified colored polymer particles may be adjusted again to a desired solid content concentration and the second classification step may be performed.

  As the wet classifier in the present invention, a conventionally known apparatus can be used. Among them, a wet cyclone or a centrifuge such as a decanter centrifuge is preferable, and a decanter centrifuge is preferable. More preferably, it is a separator. By using these apparatuses, even in an aqueous medium dispersion having a high solid content concentration, it is possible to maintain the classification performance while maintaining productivity such as short-time classification, high-accuracy classification, and high recovery rate.

As an example of a centrifuge used in the wet classification process of the present invention, FIG. 1 shows a basic structure of a decanter type centrifuge having a screw conveyor, which is provided in an outer rotating cylinder and is relatively rotatable in the outer rotating cylinder. Show.
In the decanter type centrifuge used in the present invention, the solid aqueous medium dispersion liquid to be centrifuged (for example, the aqueous medium dispersion liquid containing the colored polymer particles after the polymerization step and / or the water washing step) is used. The feed tube 1 provided in the screw conveyor 3 is fed into the outer rotary cylinder 2. When the rotating cylinder is rotated at a high speed and a high centrifugal force is applied to the solid dispersion, the solid content in the solid dispersion (in the present invention, colored polymer particles having a target particle size range) is applied to the inner wall of the outer rotating cylinder 2. ) Are separated by settling. The solid content separated and settled is squeezed by the blades 9 of the screw conveyor 3 rotating coaxially with the outer rotating cylinder and having a slight rotational difference, and sequentially proceeds in the direction of the solid discharge port 4. It is discharged from the solid material outlet. On the other hand, the liquid (separated liquid) separated from the solid content overflows and is discharged from the dam plate 5 that adjusts the liquid level, and the small colored polymer particles are also discharged together.

Since the wet classification apparatus in the present invention is an apparatus that performs classification treatment by centrifugal force, the centrifugal force in the apparatus can be changed so that the colored polymer particles obtained by classification have a desired particle size distribution. It is. During the treatment, the centrifugal force of the apparatus is in the range of 1,000 G to 3,000 G (these ranges are from 3,453 rpm when a decanter type centrifuge having a radius of the outer rotating cylinder of 7.50 cm is used. (Corresponding to 5,981 rpm) is preferable. This depends on the solid content concentration of the dispersion to be treated. If the solid content concentration is extremely low (specifically, less than 5%), the classification accuracy can be maintained even if classification is performed with a centrifugal force of less than 1,000 G. In the case of a solid content concentration of 5% or more, sufficient classification accuracy may not be maintained. Moreover, if the solid content concentration is low, the production amount per unit time is also reduced accordingly. In order to maintain both productivity and classification accuracy from the above viewpoint, 1,000 G or more, more preferably 1,500 G (when using a decanter type centrifuge with a radius of the outer rotating cylinder of 7.50 cm, it is 4,229 rpm. It is preferable to carry out the treatment with the above centrifugal force. As the centrifugal force increases, the classification accuracy can be maintained even if the solid content concentration of the dispersion is high.
Further, when a centrifugal force greater than 3,000 G is applied, the separability is improved, but the mechanical impact on the obtained colored polymer particles is too strong, so that cracks or pulverization occurs. . From the above viewpoint, it is preferable to perform the treatment with a centrifugal force of 3,000 G or less, more preferably 2800 G (corresponding to 5,778 rpm when a decanter type centrifuge with a radius of the outer rotating cylinder of 7.50 cm is used) or less. .
When the centrifugal force is in the range between the lower limit and the upper limit, it is very preferable because damage to the colored polymer particles can be suppressed while maintaining separability.

The difference between the rotational speeds of the outer rotating cylinder and the screw conveyor may be set as appropriate, but is preferably 5 to 30 revolutions per minute. If it is less than 5 revolutions, the amount of solid content (colored polymer particles) discharged relative to the amount of solid content (colored polymer particles) supplied decreases, and the solid content leaks into the separation liquid, resulting in a recovery rate. Bring about a decline. On the contrary, when the rotation exceeds 30 times, the residence time in the rotating cylinder is insufficient, so that the classification accuracy of the colored polymer particles having a too small particle diameter is insufficient.
Moreover, the dam plate which adjusts the liquid level of a separation liquid can be suitably adjusted according to the filterability of a processed material.

The centrifugal force in the case of a decanter type centrifuge indicates a force per unit mass that is generated by the rotation of the outer rotating cylinder of the decanter type centrifuge and works perpendicular to the rotation direction. The centrifugal force can be adjusted to a desired value according to the rotational speed of the outer rotating cylinder of the decanter centrifuge. The following relational expression (1) is established between the rotational speed of the outer rotating cylinder and the centrifugal force.
RCF = 11.18 (N / 1000) ² R (1)
In the formula (1), RCF represents centrifugal force (G), N represents the number of rotations per minute (rpm), and R represents the radius (cm) of the outer rotating cylinder.

In the present invention, the wet concentration is adjusted by adjusting the solid content concentration of the aqueous medium dispersion containing the colored polymer particles to a range of 5 wt% to 30 wt%, more preferably 10 wt% to 25 wt%. Supply to the device.
In the present invention, the “solid content” used for calculating the solid content concentration or the recovery rate described later is the total amount of the colored polymer particles including the small-sized colored polymer particles and the fine resin particles not containing the colorant. It is.

  When the solid content concentration of the aqueous medium dispersion is lower than the above range, the time required for the classification treatment becomes very long, which is not preferable in terms of productivity. On the other hand, when the solid content concentration exceeds the above range, the classification accuracy is lowered, so that a toner having a desired particle size distribution cannot be obtained. In addition, since a large amount of toner as a product leaks into the separation liquid on the fine particle side, the recovery rate decreases, and the loss of colored polymer particles having a required particle size increases.

In the present invention, the supply rate L (m ³ / h) of the aqueous medium dispersion containing colored polymer particles to the wet classifier is set to a ratio L / to the volume V (m ³ ) of the container of the wet classifier. V is adjusted within the range of 8.0 to 32.5, preferably within the range of 16.2 to 24.3. Here, the volume V (m ³ ) of the container of the wet classifier means the internal volume of the part of the container to which the aqueous medium dispersion is supplied in the wet classifier. For example, in the case of a decanter centrifuge Is the volume of the part of the outer rotating cylinder.
For example, when the outer rotating cylinder of the decanter centrifuge has an inner diameter of 150 mm and a length of 350 mm, the volume V (m ³ ) of the container of the wet classifier is 0.00618, and the supply amount L is 0.05. It will be -0.2 m < ³ > / h, Preferably it will be 0.1-0.15 m < ³ > / h.
When the ratio L / V of the supply amount L (m ³ / h) to the wet classifier to the volume V (m ³ ) of the centrifuge container is smaller than the above range, the classification accuracy and the recovery rate are improved. Since the processing amount per unit time is small, productivity is extremely lowered. On the other hand, if the ratio L / V is larger than the above range, the residence time in the wet classifier is extremely reduced, and the small-sized colored polymer particles are not sufficiently removed, resulting in low classification accuracy, and coloring. Since the leakage and loss of polymer particles into the effluent becomes very large, the recovery rate is also low.

  According to the present invention, using a wet classifier by centrifugal force, the solid content concentration of the aqueous medium dispersion containing colored polymer particles to be classified, the centrifugal force of the wet classifier, and the wet classifier By performing wet classification by adjusting the ratio (L / V) of the supply rate (L) of the aqueous medium dispersion to the solution V of the wet classifier within the above range, the target particle size range is exceeded. Particles that deviate to the small particle size side are efficiently removed, and the particle size distribution of the colored polymer particles can be made sharper. Therefore, it is possible to classify colored polymer particles having a necessary particle size range with high accuracy, high recovery rate, and in a short time.

Further, among the colored polymer particles having a small particle diameter, typically, those having a particle diameter of 0.6 to 5.0 μm, and further 0.6 to 3.0 μm are particularly used for members in the developing machine. Since it is easy to adhere and accumulate, filming is caused, and as a result, white streaks on the printing surface are generated, which is a major cause of impairing printing durability.
In contrast, the present invention has a very high effect of removing colored polymer particles having a particle size of about 1 μm, which is a major cause of printing durability.
The specific classification performance varies depending on various conditions such as the particle size distribution of the colored polymer particles before classification treatment and the type of the wet classifier used. When the classification conditions can be particularly optimized, for example, the volume average particle diameter (Dv) of the colored polymer particles before classification treatment is 6 to 8 μm, and the total particle diameter range of the population is 0.6. In the present invention, the number frequency in the particle size range of 0.6 to 5.0 μm at ˜30 μm is 31 to 40%, and the number frequency in the particle size range of 0.6 to 3.0 μm is about 9 to 15%. The volume average particle diameter (Dv) of the colored polymer particles recovered by the classification process is almost the same as the above range, and the total particle diameter range of the population is 0. The number frequency in the particle size range of 0.6 to 5.0 μm at .6 to 30 μm can be 20 to 30%, and the number frequency in the particle size range 0.6 to 3.0 can be 4 to 8%.
The number frequency in the present invention means the ratio of the number of particles included in a part of the particle size range noted in the population to the total number of particles included in the particle size range defined as the population. is there.
At that time, the recovery rate of the aqueous medium dispersion containing the classified colored polymer particles can be 95 to 100%, preferably 97 to 100%, and more preferably 98 to 100.
Here, the recovery rate of the aqueous medium dispersion containing the classified colored polymer particles is recovered by classification with respect to the solid content contained in the entire aqueous medium dispersion containing the colored polymer particles before classification. It is a ratio of the amount of solid content to be made. This solid content does not include a dispersion stabilizer.

In the present invention, the number frequency of small-sized colored polymer particles is determined by measuring the particle size of each individual particle by an appropriate method arbitrarily selected in a state where the particle group to be measured is sufficiently dispersed. Can be identified.
As an example of the measurement method, an appropriate amount of a sample of colored polymer particles is taken, mixed in a container with a dispersion solvent and a surfactant as necessary, stirred, further diluted by adding a dispersion solvent, and ultrasonic dispersion. Disperse by machine. Thereafter, each particle size is measured by a flow type particle image analyzer. There is no problem if the number of particles included in the particle size range of the population counted in this measurement is in the range of 1500 to 5000.

  In the particle diameter measurement, the number frequency of 0.6 to 5.0 μm is preferably 30% or less in terms of image quality and durability. When the number frequency of 0.6 to 5.0 μm exceeds 30%, charge amount fluctuation and fogging occur in continuous printing. Moreover, it is preferable that the number frequency of 0.6-3.0 micrometers in the particle diameter measurement with a flow type particle image analyzer is 12% or less. When the number frequency of 0.6 to 3.0 μm exceeds 12%, filming is likely to occur, and white streaks on the printing surface become prominent mainly in continuous printing.

(6) Dehydration and drying step When the washing step is performed after the classification step or after the classification step, the aqueous dispersion of colored polymer particles is dehydrated by the dehydration step, and then dried and dried. Colored polymer particles are obtained.

  As the dehydration method, various known methods can be used, and there is no particular limitation. Examples thereof include a centrifugal filtration method, a vacuum filtration method, and a pressure filtration method. Of these, the centrifugal filtration method is preferred. Examples of the filtration dehydrator include peeler centrefuge and siphon peeler centrefuge.

  In the centrifugal filtration method, centrifugal gravity is usually set to 400 to 3,000 G, preferably 800 to 2,000 G. The water content of the recovered product after dehydration is usually 5 to 30% by weight, preferably 8 to 25% by weight. If the water content is high, the drying process takes time, and even if the ionic component concentration of water is low, if the water content is high, impurities are concentrated by drying, and the environmental dependency of the polymerized toner increases.

  The drying method is not particularly limited, and various known methods can be used. For example, various methods such as vacuum drying, air flow drying, and spray dryer can be used.

(7) Colored polymer particles The colored polymer particles obtained through the above steps will be described (the colored polymer particles below include both core-shell type and non-core type particles).
The colored polymer particles constituting the polymerized toner of the present invention preferably have a volume average particle diameter Dv of 5 to 10 μm, more preferably 6 to 8 μm. If Dv is less than these ranges, the fluidity of the polymerized toner may decrease, transferability may deteriorate, blurring may occur, and print density may decrease. If these ranges are exceeded, the resolution of the image may be reduced. May decrease.

  The ratio Dv / Dp between the volume average particle diameter Dv and the number average particle diameter Dp is preferably 1.0 to 1.3, and more preferably 1.0 to 1.2. When the ratio Dv / Dp is out of the above range, blurring may occur when printing is performed using the obtained polymerized toner, and transferability, print density, and resolution may be reduced. The volume average particle diameter and the number average particle diameter of the colored polymer particles can be measured using, for example, Multisizer (manufactured by Beckman Coulter).

  The colored polymer particles constituting the polymerized toner of the present invention preferably have a sphericity Sc / Sr of 1.0 to 1.3, and a sphericity Sc / Sr of 1.0 to 1.2. It is more preferable to use what is. If the sphericity Sc / Sr exceeds these ranges, when the resulting polymerized toner is printed, the transferability may be lowered, or the fluidity of the toner may be lowered, and the toner may be easily blurred.

The sphericity Sc / Sr of the colored polymer particles is determined as follows. Colored polymer particles are photographed with an electron microscope, and the resulting photograph is taken up by an image processing analyzer (trade name “Luzex IID”, manufactured by Nireco Corporation). Measure under 100 conditions. It is obtained by averaging the sphericity Sc / Sr of the 100 colored polymer particles obtained.
Sphericality = Sc / Sr
Sc: area of a circle having the absolute maximum length of the colored polymer particles as a diameter Sr: substantial projected area of the colored polymer particles

(8) Polymerized toner In the present invention, the colored polymer particles can be used as they are for the development of electrophotography as a polymerized toner. However, in order to adjust the chargeability, fluidity, storage stability, etc. of the polymerized toner, Using a high-speed stirrer, etc., the colored polymer particles, the external additive, and other particles as required can be mixed to obtain a one-component polymerized toner. In addition to colored polymer particles, external additives and other particles as required, carrier particles such as ferrite and iron powder are further mixed by various known methods, and two-component polymer toner It can also be.

Examples of the external additive include inorganic particles and organic resin particles that are usually used for the purpose of improving fluidity and chargeability. Examples of inorganic particles include silica, aluminum oxide, titanium oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, and cerium oxide. Examples of organic resin particles include methacrylic acid ester polymers and acrylic acid esters. Examples thereof include a polymer, a styrene-methacrylic acid ester copolymer, a styrene-acrylic acid ester copolymer, a melamine resin, and a core-shell type particle in which a core is a styrene polymer and a shell is a methacrylic acid ester polymer. Of these, silica and titanium oxide are preferable, and particles having a hydrophobic surface are preferable, and silica having a hydrophobic surface is more preferable. It is more preferable to use two or more types of hydrophobized silica in combination.
Although the addition amount of an external additive is not specifically limited, Usually, it is 0.1-6 weight part with respect to 100 weight part of colored polymer particles.

The polymerized toner obtained through each of the above steps has high resolution even when durable printing is performed, and does not cause filming or fogging and has excellent printing durability. According to the production method of the present invention, a polymerized toner having such excellent printing performance can be produced stably and efficiently.
Hereinafter, an image forming apparatus to which a polymerized toner manufactured according to the present invention is applied will be described with reference to the drawings.

FIG. 2 shows an example of the configuration of an image forming apparatus to which an electrostatic latent image toner is provided provided by the method for producing polymerized toner of the present invention. The image forming apparatus shown in FIG. 2 has a photosensitive drum 10 as a photosensitive member, and the photosensitive drum 10 is mounted so as to be rotatable in the direction of the arrow. The photosensitive drum 10 is obtained by providing a photoconductive layer on a conductive support drum body. This photoconductive layer is composed of, for example, an organic photoreceptor, a selenium photoreceptor, a zinc oxide photoreceptor, an amorphous silicon photoreceptor, or the like. Among these, those composed of organic photoreceptors are preferable. The photoconductive layer is bound to a conductive support drum. Examples of the resin used for binding the photoconductive layer to the conductive support drum include polyester resin, acrylic resin, polycarbonate resin, phenol resin, and epoxy resin. Among the above, polycarbonate resin is preferable.
A charging roll 11 as a charging member, a laser irradiation device 12 as an exposure device, a developing device 20, a transfer roll 13, and a cleaning blade 22 are arranged around the photosensitive drum 10 along the circumferential direction.
A fixing device 23 is provided on the downstream side of the photosensitive drum 10 in the transport direction. The fixing device 23 includes a heat roll 23a and a support roll 23b.
The transfer path of the transfer material 14 is provided so as to pass between the photosensitive drum 10 and the transfer roll 13 and between the heat roll 23a and the support roll 23b.

The process of forming an image using the image forming apparatus shown in FIG. 2 includes a charging process, an exposure process, a development process, a transfer process, a cleaning process, and a fixing process as described below.
The charging step is a step of uniformly charging the surface of the photosensitive drum 10 positively or negatively by the charging member. In addition to the charging roll 11 shown in FIG. 2, the charging method using the charging member includes a contact method in which charging is performed using a fur brush, a magnetic brush, a blade, and the like, and a non-contact charging method using corona discharge. It is also possible to replace with a contact system or a non-contact system.

  In the exposure process, the surface of the photosensitive drum 10 is irradiated with light corresponding to the image signal by a laser irradiation device 12 as an exposure device as shown in FIG. This is a step of forming an electrostatic latent image. As an exposure apparatus, there is an LED irradiation apparatus in addition to the one shown in FIG.

  The developing process is a process in which the developing device 20 attaches the toner 19 to the electrostatic latent image formed on the surface of the photosensitive drum 10 by the exposure process. In the reverse development, the toner 19 is attached only to the light irradiation portion. In the regular development, a bias voltage is applied between the developing roll 15 and the photosensitive drum 10 so that the toner 19 is attached only to the light non-irradiated portion.

A developing device 20 provided in the image apparatus shown in FIG. 2 is a developing device used in the one-component contact developing method, and includes a stirring blade 18, a developing roll 15, a supply roll 17, and a casing 21 in which toner 19 is accommodated. Have
The developing roller 15 is disposed so as to partially contact the photosensitive drum 10 and rotates in the direction B opposite to the photosensitive drum 10. The supply roll 17 comes into contact with the development roll 15 and rotates in the same direction C as the development roll 15. The supply roll 17 receives supply of the toner 19 charged by the stirring blade 18 in the toner tank 21 a, and the toner is placed on the outer periphery of the supply roll 17. 19 is attached, and the toner 19 is supplied to the outer periphery of the developing roll 15. Other development methods include a one-component non-contact development method, a two-component contact development method, and a two-component non-contact development method.

  Around the developing roll 15, a developing roll blade 16 as a toner layer thickness regulating member is disposed at a position between the contact point with the supply roll 17 and the contact point with the photosensitive drum 10. The developing roll blade 16 is made of, for example, a conductive rubber elastic body or metal.

The transfer process is a process of transferring the toner image on the surface of the photosensitive drum 10 formed by the developing device 20 to a transfer material 14 such as paper, and is usually transferred by a transfer roll 13 as shown in FIG. There are other types of belt transfer and corona transfer.
The cleaning process is a process of cleaning the toner remaining on the surface of the photosensitive drum 10, and the cleaning blade 22 is used in the image forming apparatus shown in FIG. The cleaning blade 22 is made of, for example, a rubber elastic body such as polyurethane or acrylonitrile-butadiene copolymer.

  In the image forming apparatus shown in FIG. 2, the surface of the photosensitive drum 10 is negatively charged by the charging roll 11, and an electrostatic latent image is formed by the laser irradiation device 12. The toner image is developed by 20. Next, the toner image on the photosensitive drum 10 is transferred to a transfer material 14 such as paper by the transfer roll 13, and the residual toner remaining on the surface of the photosensitive drum 10 is cleaned by the cleaning blade 22, and then the next Enter image forming cycle.

  The fixing step is a step of fixing the toner image transferred to the transfer material 14, and in the image forming apparatus shown in FIG. 2, at least one of a heat roll 23a and a support roll 23b heated by a heating means (not shown) is rotated. Then, pressurizing and heating is performed while passing the transfer material 14 between them.

  The image forming apparatus shown in FIG. 2 is for monochrome use, but it is possible to apply the polymerized toner produced by the present invention to a color image forming apparatus such as a copying machine or a printer that forms a color image. .

The production method of the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Parts and% are based on weight unless otherwise specified.
The test methods performed in this example are as follows.

(1) Measurement of number-of-particles frequency by flow type particle image analyzer The number of particles for specifying the particle size distribution of the colored polymer particles before the classification step and the particle size distribution of the colored polymer particles after the classification step The number frequency was measured according to the following procedure.
First, 50 to 70 mg of a sample of colored polymer particles was weighed into a 100 ml hard beaker, and 0.5 ml of a surfactant was added and stirred well. Thereafter, the mixture was diluted with ion-exchanged water until the total amount became 40 ml, and dispersed for 5 minutes with a bath-type ultrasonic disperser. The toner aqueous dispersion thus obtained was measured with a flow particle image analyzer (trade name “FPIA-2100” manufactured by Simex Corporation). In this measurement, the count number of all particles contained in the population of 0.6 to 30 μm is adjusted to be in the range of 1500 to 5000, and a small particle size range of 0.6 to 5.0 μm. The number frequency of colored polymer particles with a particle size and the number frequency of small particle size colored polymer particles with a particle size range of 0.6 to 3.0 μm were measured.

(2) Printing test (number of filming occurrences)
A commercially available non-magnetic one-component developing type printer (18 sheets) was used for the printing test. A polymerization toner to be used for the test was put in the developing device of this printer, and left for a day and night in an environment of a temperature of 23 ° C. and a humidity of 50%. A solid image was printed every 1,000 sheets, and the presence or absence of vertical stripes on the printed surface was confirmed. The number of vertical stripes that was first confirmed in a solid image was defined as the number of white stripes generated.

(3) Determination of recovery rate The recovery rate of the colored polymer particles was determined by the following method.
A part of the dispersion containing the colored polymer particles was sampled, and the weight of the sampled dispersion containing the colored polymer particles was measured. Next, when this dispersion was subjected to acid cleaning, as it was before acid cleaning, sulfuric acid was added to dissolve the dispersion stabilizer, followed by filtration with a Buchner funnel. The total amount of the colored polymer particles including the colored polymer particles and the fine resin particles not including the colored polymer particles) was dried, and the weight of the solid content after drying was measured. From these two weights, the solid content concentration of the sampled dispersion was calculated from the following equation.
Solid content concentration (%) of sampled dispersion = (solid content weight of sampled dispersion) / (dispersion weight of sampled dispersion) × 100
Next, from the solid content concentration of the sampled dispersion obtained above, the solid content of each dispersion was converted by the following formula.
Solid content of dispersion = dispersion weight × solid content concentration of sampled dispersion Based on the solid content of the dispersion obtained from the above formula, the recovery rate of the colored polymer particles was calculated from the following formula.
Recovery rate (%) = (Solid content of dispersion after wet classification) / (Solid content of dispersion before wet classification) × 100

Example 1
88 parts of styrene and 12 parts of n-butyl acrylate as a monovinyl monomer and C.I. I. 7 parts of Pigment Yellow 180 were subjected to a dispersion treatment with a media-type disperser (trade name “OB Bead Mill” manufactured by Turbo Kogyo Co., Ltd.) to obtain a polymerizable monomer dispersion. To the obtained polymerizable monomer dispersion, 4 parts of a positive charge control resin (quaternary ammonium base-containing styrene / acrylic resin), dipentaerythritol hexamyristate (DSC maximum endothermic peak 66.2 ° C., molecular weight 1514) 8 Part (release agent), polymethacrylic acid ester macromonomer (manufactured by Toa Gosei Chemical Co., Ltd., trade name “AA6”, Tg = 94 ° C.) 0.25 part, and the polymerizable monomer composition 119 is mixed. .25 parts were obtained.

  On the other hand, an aqueous solution in which 6.5 parts of magnesium chloride (water-soluble polyvalent metal salt) is dissolved in 250 parts of ion-exchanged water and an aqueous solution in which 5 parts of sodium hydroxide (alkali metal hydroxide) are dissolved in 50 parts of ion-exchanged water. The mixture was gradually added under stirring to prepare 311.5 parts of a magnesium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion.

  The above polymerizable monomer composition is charged into the magnesium hydroxide colloidal dispersion obtained as described above and stirred, and then 0.7 parts of divinylbenzene as a crosslinking agent and tert-dodecanethiol 1.0 as a molecular weight modifier. 5 parts of t-butyl peroxy-2 ethylhexanoate (manufactured by NOF Corporation, trade name “Perbutyl O”) was added as a polymerization initiator. This was subjected to high shear stirring using an in-line type emulsifying disperser (trade name “Ebara Milder” manufactured by Ebara Seisakusho) to form droplets of the polymerizable monomer composition.

  The dispersion obtained by forming the droplets was placed in a reactor and the temperature was raised to 90 ° C. to carry out a polymerization reaction. After the polymerization conversion reached almost 100%, 1 part of methyl methacrylate was added to the reactor as a polymerizable monomer for the shell, and 10 minutes later, 2,2′-azobis [2-methyl-N— (2-Hydroxyethyl) -propionamide] (manufactured by Wako Pure Chemicals, trade name “VA-086”) (water-soluble initiator) (aqueous solution) in which 0.1 part was dissolved in 10 parts of ion-exchanged water was added. After continuing the polymerization for 3 hours, the reaction was stopped by cooling to obtain an aqueous dispersion of colored polymer particles.

  Regarding the particle diameter of the slurry containing colored polymer particles obtained by polymerization, the volume average particle diameter (Dv) of the slurry is 6.50 μm, and the number frequency of 0.6 to 5.0 μm is 34.84%, 0.6. The number frequency of ˜3.0 μm was 10.74%.

The pH of the aqueous dispersion of the colored polymer particles was 11. The aqueous dispersion 0.5 m ³ of the colored polymer particles was adjusted to pH 6.0 with sulfuric acid and dehydrated and washed. The colored polymer particles were made into an aqueous dispersion again with ion-exchanged water so that the solid content concentration was 17 wt%.

  The aqueous dispersion obtained by the redispersion was decanted from a decanter centrifuge having a screw conveyor (inner radius of outer rotating cylinder: 7.7 cm, inner length: 35 cm, manufactured by Sakai Kogyo Co., Ltd., trade name “TOMO-E”). DECANTER “PTM006” was used for wet classification under the following conditions.

<Conditions for wet classification>
Solid content concentration of aqueous dispersion: 17%
Centrifugal force: 2,100 G (4939 rpm)
Difference in rotational speed between outer rotating cylinder and screw conveyor: 20 rpm
Aqueous dispersion supply amount (L): 0.1 m ³ / hr
Equipment volume (V): 0.00651 m ³
(L / V): 15.36
Number of treatments: 1 time The time required for this treatment was 5 hours.

  The colored polymer particles contained in the aqueous medium dispersion recovered by the wet classification treatment have a volume average particle size (Dv) of 6.53 μm, a number frequency of 0.6 to 5.0 μm, 28.94%, and 0.8. The number frequency of 6 to 3.0 μm was 6.27%. Further, the recovery rate of the aqueous medium dispersion after one wet classification treatment with respect to the aqueous medium dispersion initially supplied to the wet classifier was 99.1%.

  The slurry obtained as described above was dehydrated and dried to obtain dried colored polymer particles. Hydrophobized colloidal silica (trade name “REA-200” manufactured by Nippon Aerosil Co., Ltd.) 0.5 part (trade name “NA-50Y manufactured by Nippon Aerosil Co., Ltd.) with respect to 100 parts by weight of the dried colored polymer particles. ]) 1.0 part was added, and it mixed using the Henschel mixer, and prepared the polymerization toner. The resulting polymerized toner was subjected to a printing test using a commercially available non-magnetic one-component printer. The test results are shown in Table 1.

(Example 2)
The processing was performed under the same conditions as in Example 1 except that the number of processings was changed to 2 in Example 1. In the second classification after the first treatment, the solid obtained in the first treatment was diluted with ion-exchanged water so that the solid content concentration was 20%, and then the second treatment was performed. The time required for this treatment was 10 hours.

  The colored polymer particles contained in the aqueous medium dispersion recovered by the wet classification treatment have a volume average particle diameter (Dv) of 6.56 μm, a number frequency of 0.6 to 5.0 μm of 25.74%, and 0.005. The number frequency of 6 to 3.0 μm was 5.64%. Further, the recovery rate of the aqueous medium dispersion after the wet classification twice treatment with respect to the aqueous medium dispersion initially supplied to the wet classifier was 98.9%. The obtained polymerized toner was dried and evaluated for printing under the same conditions as in Example 1.

(Comparative Example 1)
The processing was performed under the same conditions as in Example 1 except that the processing conditions of the decanter centrifuge in Example 1 were changed as follows.
<Conditions for wet classification>
Solid content concentration of slurry: 18%
Centrifugal force: 2,100 G (4939 rpm)
Differential speed with screw conveyor: 20rpm
Slurry supply amount (L): 0.3 m ³ / hr
Equipment volume (V): 0.00651 m ³
(L / V): 46.08
Number of treatments: 1 time The time required for this treatment was 1.7 hours.

  The colored polymer particles contained in the aqueous medium dispersion recovered by the wet classification treatment have a volume average particle diameter (Dv) of 6.52 μm, a number frequency of 0.6 to 5.0 μm of 29.31%, and 0.3. The number frequency of 6 to 3.0 μm was 7.15%. Further, the recovery rate of the aqueous medium dispersion after one wet classification treatment with respect to the aqueous medium dispersion initially supplied to the wet classifier was 89.2%. The obtained polymerized toner was dried and evaluated for printing under the same conditions as in Example 1.

(Comparative Example 2)
The treatment was performed under the same conditions as in Example 1 except that the solid content concentration of the feed solution was changed to 32% in Example 1. The time required for this treatment was 5 hours.

  The colored polymer particles contained in the aqueous medium dispersion recovered by the wet classification treatment have a volume average particle diameter (Dv) of 6.51 μm, a number frequency of 0.6 to 5.0 μm, a frequency of 32.65%, and a. The number frequency of 6 to 3.0 μm was 9.33%. Moreover, the product recovery rate after one wet classification process with respect to the aqueous medium dispersion liquid first supplied to the wet classifier was 80.3%. The obtained polymerized toner was dried and evaluated for printing under the same conditions as in Example 1.

(Comparative Example 3)
In Example 1, the treatment was performed under the same conditions as in Example 1 except that the treatment conditions of the decanter type centrifuge were changed as follows.
<Conditions for wet classification>
Solid content concentration of slurry: 18%
Centrifugal force: 2,100 G (4939 rpm)
Differential speed with screw conveyor: 20rpm
Slurry supply amount (L): 0.04 m ³ / hr
Equipment volume (V): 0.00651 m ³
(L / V): 6.14
Number of treatments: 1 Time required for this treatment was 12.5 hours.

  The colored polymer particles contained in the aqueous medium dispersion recovered by the wet classification treatment have a volume average particle diameter (Dv) of 6.53 μm, a number frequency of 0.6 to 5.0 μm, 28.87%, and 0.8. The number frequency of 6 to 3.0 μm was 6.13%. Moreover, the product recovery rate after one wet classification process with respect to the aqueous medium dispersion liquid first supplied to the wet classifier was 99.3%. The obtained polymerized toner was dried and evaluated for printing under the same conditions as in Example 1.

(Comparative Example 4)
The processing was performed under the same conditions as in Example 1 except that the processing conditions of the decanter centrifuge in Example 1 were changed as follows.
<Conditions for wet classification>
Solid content concentration of slurry: 18%
Centrifugal force: 800G (3048rpm)
Differential speed with screw conveyor: 20rpm
Slurry supply amount (L): 0.1 m ³ / hr
Equipment volume (V): 0.00651 m ³
(L / V): 15.36
Number of treatments: 1 time The time required for this treatment was 5 hours.

  The colored polymer particles contained in the aqueous medium dispersion recovered by the wet classification treatment have a volume average particle size (Dv) of 6.50 μm, a number frequency of 0.6 to 5.0 μm of 33.61%, and 0.001. The number frequency of 6 to 3.0 μm was 10.37%. Moreover, the product recovery rate after one wet classification process with respect to the aqueous medium dispersion liquid first supplied to the wet classifier was 88.7%. The obtained polymerized toner was dried and evaluated for printing under the same conditions as in Example 1.

(Comparative Example 5)
The processing was performed under the same conditions as in Example 1 except that the processing conditions of the decanter centrifuge in Example 1 were changed as follows.
<Conditions for wet classification>
Solid content concentration of slurry: 18%
Centrifugal force: 4,000 G (6816 rpm)
Differential speed with screw conveyor: 20rpm
Slurry supply amount (L): 0.1 m ³ / hr
Equipment volume (V): 0.00651 rpm
(L / V): 15.36
Number of treatments: 1 time The time required for this treatment was 5 hours.

  The colored polymer particles contained in the aqueous medium dispersion recovered by the wet classification treatment have a volume average particle diameter (Dv) of 6.35 μm, a number frequency of 0.6 to 5.0 μm of 38.26%, and a. The number frequency of 6 to 3.0 μm was 7.27%. Moreover, the product recovery rate after one wet classification process with respect to the aqueous medium dispersion liquid first supplied to the wet classifier was 97.4%. The obtained polymerized toner was dried and evaluated for printing under the same conditions as in Example 1.

〔result〕
Table 1 shows the characteristics of the toners obtained in the examples and the comparative examples and the results of the image tests performed in the above-described procedure.

[Summary of results]
It was also observed that the toners obtained in Examples 1 and 2 did not generate white streaks on the printed matter even on 5,000 continuous prints, and good solid printing was possible.
On the other hand, Comparative Example 1 in which the ratio L / V to the supply rate L of the aqueous medium dispersion containing the colored polymer fine particles and the volume V of the wet classifier is 46.08 is 0.6 to 3.0 μm. The number frequency was higher than in Examples 1 and 2, and the recovery rate decreased. In addition, white streaks were generated in the printed matter on 4,000 continuous prints, and when this cartridge was disassembled and observed, yellow foreign matter was filmed on the developing blade.
The toner obtained in Comparative Example 2 in which the solid content concentration of the aqueous medium dispersion containing colored polymer fine particles supplied to the wet classifier is 32% is 0.6 to 5.0 μm in number frequency, and 0.6. The number frequency of ˜3.0 μm was higher than those in Examples 1 and 2, and a significant reduction in the recovery rate was observed. In addition, white streaks were generated in the printed matter on 2500 continuous prints, and when this cartridge was disassembled and observed, yellow foreign matter was filmed on the developing blade.
Toner obtained by Comparative Example 3 in which the supply rate L (m ³ / h) of the aqueous dispersion containing the colored polymer particles and the ratio L / V to the volume V (m ³ ) of the wet classifier is 6.14 Compared with Examples 1 and 2, there is no significant difference in the number frequency and the recovery rate, and no white streaks are observed in the printed material on 5,000 continuous prints, and good printing can be performed. It was possible. However, the time required for the wet classification treatment was 12.5 hours, particularly 2.5 times that of Example 1.
The toner obtained in Comparative Example 4 in which the centrifugal force of the centrifuge was set to 800 G was insufficient in removing the small-sized colored polymer particles that deviated from the target particle size range. White streaks were generated in the product, and when this cartridge was disassembled and observed, yellow foreign matter was filmed on the developing blade.
With the toner of Comparative Example 5 in which the centrifugal force of the centrifugal separator was 4000 G, white streaks occurred on the printed matter with 50 continuous prints. When this cartridge was disassembled and observed, yellow foreign matter was filmed on the developing blade. Further, since the volume average particle size after wet classification was smaller than that of the supplied slurry, the surface of the dried colored polymer particles using a field emission scanning microscope (manufactured by Hitachi, Ltd., trade name “S-4700”). Was observed at a magnification of 5,000 times, and crushed toner was confirmed.

It is the figure which showed the structure of the decanter type | mold centrifuge which has the screw conveyor provided in the outer side rotation cylinder and the outer side rotation cylinder so that relative rotation was possible used for this invention. FIG. 4 is a diagram illustrating a configuration example of an image forming apparatus to which an electrostatic latent image toner is provided, which is provided by the method for producing polymerized toner of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Feed tube 2 Outer rotating cylinder 3 Screw conveyor 4 Solid matter discharge port 5 Dam plate 6 Drive motor 7 Gear box 8 Supply port 9 Screw blade 10 Photoreceptor drum 11 Charging roll 12 Laser irradiation apparatus 13 Transfer roll 14 Transfer material 15 Developing roll 16 Developing Roll Blade 17 Supply Roll 18 Stirring Blade 19 Toner 20 Developing Device 21 Casing 21a Toner Tank 22 Cleaning Blade 23 Fixing Device 23a Heat Roll 23b Support Roll

Claims (6)

A polymerization process for obtaining colored polymer particles by polymerizing a polymerizable monomer composition containing a polymerizable monomer and a colorant in a state of being dispersed in an aqueous medium, and washing the colored polymer particles In a method for producing a polymerized toner comprising a washing step and a classification step of classifying the colored polymer particles to have a predetermined particle size distribution,
In the classification step, the aqueous medium dispersion containing the colored polymer particles is supplied to a wet classification apparatus that performs classification by centrifugal force, and classification is performed under the following conditions (1), (2), and (3). A method for producing a polymerized toner.
(1) The solid content concentration of the aqueous medium dispersion supplied to the wet classifier is in the range of 5 to 30% by weight.
(2) The centrifugal force of the wet classifier is in the range of 1,000 to 3,000 G.
(3) The ratio L / V of the supply rate L (m ³ / h) of the aqueous medium dispersion to the wet classifier to the volume V (m ³ ) of the wet classifier is in the range of 8 to 32.5. .   The classifying step is a wet classifier using an aqueous medium itself containing the colored polymer particles obtained in the polymerization step, or an aqueous medium further supplemented with an aqueous medium containing the colored polymer particles as an aqueous medium dispersion. To the wet classification apparatus as an aqueous medium dispersion obtained by adding the aqueous medium to the colored polymer particles obtained in the washing process. The method for producing a polymerized toner according to claim 1, wherein the method is carried out subsequently.   3. The method for producing a polymerized toner according to claim 1, wherein the wet classifier is a wet cyclone or a decanter centrifuge.   The volume average particle size (Dv) of the colored polymer particles obtained in the polymerization step is 6 to 8 μm, and the number frequency of the particle size range 0.6 to 5.0 μm in the total particle size range 0.6 to 30 μm. According to the classification step, the volume average particle size (Dv) of the colored polymer particles is 6 to 8 μm, and the particle size range 0.6 to 30 μm in the total particle size range 0.6 to 30 μm. The method for producing a polymerized toner according to claim 1, wherein the number frequency of ˜5.0 μm is 20 to 30%.   The volume average particle size (Dv) of the colored polymer particles obtained in the polymerization step is 6 to 8 μm, and the number frequency of the particle size range 0.6 to 5.0 μm in the total particle size range 0.6 to 30 μm. The volume average particle size (Dv) of the colored polymer particles is 31 to 40% and the number frequency of the particle size range 0.6 to 3.0 μm is 9 to 15%. The number frequency of the particle size range 0.6 to 5.0 μm in the total particle size range 0.6 to 30 μm is 20 to 30%, and the number frequency of the particle size range 0.6 to 3.0 μm is 6 to 8 μm. The method for producing a polymerized toner according to any one of claims 1 to 4, wherein the content is 4 to 8%.   6. The method for producing a polymerized toner according to claim 1, wherein the polymerization in the polymerization step is suspension polymerization.

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