JP2010122677A - Method for manufacturing developer - Google Patents

Abstract

To prevent clogging in a nozzle and a check valve and to perform stable atomization, to obtain toner particles with a small particle diameter having a more uniform composition.
When a dispersion is prepared by mixing a granular mixture of toner materials and an aqueous medium, the surface tension of the dispersion is adjusted to 50 mN / m or more using a surfactant.
[Selection] Figure 1

Description

  The present invention relates to a method for producing a developer for developing an electrostatic charge image and a magnetic latent image in electrophotography, electrostatic printing, magnetic recording, and the like.

  Conventionally, in electrophotography, an electric latent image is formed on an image carrier, the latent image is then developed with toner, the toner image is transferred onto a transfer material such as paper, and then a means such as heating and pressing. To settle. The toner to be used is not only a conventional single color black, but also forms an image using a plurality of colors of toner in order to form a full color image.

  The toner includes a two-component developer used by mixing with carrier particles and a one-component developer used as a magnetic toner or a nonmagnetic toner. These toners are usually produced by a kneading and pulverizing method. This kneading and pulverizing method is a method for producing desired toner particles by melt-kneading a binder resin, a release agent such as a pigment and wax, a charge control agent and the like, finely pulverizing them after cooling, and classifying them. Depending on the purpose, inorganic and / or organic fine particles are added to the surface of the toner particles produced by the kneading and pulverization method to obtain a toner.

  In the case of toner particles produced by a kneading and pulverizing method, the shape thereof is usually indeterminate and the surface composition thereof is not uniform. Although the shape and surface composition of the toner particles vary slightly depending on the pulverization properties of the materials used and the conditions of the pulverization process, it is difficult to intentionally control the shape.

  In particular, when a material with high pulverization properties is used, it is further pulverized or changed in shape due to various stresses in the developing machine. As a result, in the two-component developer, the pulverized toner is Adhering to the surface of the carrier accelerates the charging deterioration of the developer, and in the case of a one-component developer, the particle size distribution expands, the finely divided toner scatters, and the developability decreases with changes in the toner shape. However, there has been a problem that the image quality deteriorates.

  Further, when the toner contains a release agent such as wax, pulverization is likely to occur at the interface between the binder resin and the release agent, so that the release agent may be exposed on the surface of the toner. In particular, in the case of a toner composed of a highly elastic resin that is not easily pulverized and a brittle wax such as polyethylene, polyethylene is often exposed on the surface of the toner. Although such toner is advantageous for releasability at the time of fixing and cleaning of untransferred toner from the photoreceptor, the toner on the surface of the toner is subjected to mechanical force such as shearing force in the developing machine. And can be easily transferred to a developing roll, an image carrier, a carrier, and the like. For this reason, the developing roll, the image carrier, the carrier, and the like are easily contaminated by wax, and the reliability as a developer may be lowered.

  Under such circumstances, in recent years, an emulsion polymerization aggregation method has been proposed as a toner production method in which the shape and surface composition of toner particles are intentionally controlled (see, for example, Patent Document 1 and Patent Document 2).

  In the emulsion polymerization aggregation method, a resin dispersion is prepared by emulsion polymerization, while a colorant dispersion is prepared by dispersing a colorant in a solvent, and these are mixed to form aggregated particles corresponding to the toner particle size. The toner particles are then fused to obtain toner particles. According to this emulsion polymerization aggregation method, the toner shape can be arbitrarily controlled from an indeterminate shape to a spherical shape by selecting the heating temperature condition.

  In the emulsion polymerization aggregation method, it can be obtained by aggregating and fusing at least a dispersion of resin fine particles and a dispersion of a colorant under predetermined conditions. However, the emulsion polymerization aggregation method has limitations on the types of resins that can be synthesized and is suitable for the production of styrene acrylic copolymers, but it is possible to apply polyester resins that are known to have good fixability. Can not. Further, when agglomerating fine particles, a water-soluble metal salt, particularly a water-soluble metal salt having a high valence is adopted in that a desired particle size distribution can be obtained. On the other hand, as a method for producing a toner using a polyester resin, there is a phase inversion emulsification method in which a pigment dispersion or the like is added to a solution dissolved in an organic solvent and water is added thereto. However, it is necessary to remove and recover the organic solvent. is there. Although a method for producing fine particles by mechanical shearing in an aqueous medium without using an organic solvent has been proposed, it is necessary to supply a molten resin or the like to a stirrer, which makes handling difficult. Further, the degree of freedom in shape control is low, and the toner shape cannot be arbitrarily controlled from an indeterminate shape to a spherical shape (for example, see Patent Document 3).

  In view of such a situation, as a production method in which a polyester resin is used and the particle size distribution and the toner shape can be freely designed, the colorant can be uniformly dispersed by using a kneader. There is a simplified method of atomizing to sub-micron order collectively by mechanical shearing in a medium (see, for example, Patent Document 4). When this method is used, toner particles are produced by uniformly agglomerating the fine particles, so that a small-diameter toner having a uniform composition can be produced. In addition to high image quality and low CPC, the fixing property is further improved. Energy savings can be expected because very good polyester can be used.

  In this production method, atomization of the polyester resin is achieved by heating to a Tg of the resin or higher, adjusting the pH to alkali, and applying shear force while neutralizing the carboxyl group at the end of the polyester resin. From the viewpoint of hydrolysis, a high-pressure homogenizer that can instantaneously provide a shearing force is preferably used as the atomizer.

  In addition, various methods for producing a developer using an aqueous medium are known (see, for example, Patent Documents 5, 6, 7, and 8).

  However, when the kneaded material is atomized using a high-pressure homogenizer, there is a drawback that the atomization process becomes unstable because the reverse-support valve, which is essential for generating high pressure, is likely to be clogged.

  An object of the present invention is to obtain a small particle size developer having a uniform composition by stably performing the atomization step.

A method for producing a developer includes a step of preparing a dispersion having a surface tension of 50 mN / m or more by mixing a particulate mixture of toner materials containing a binder resin with an aqueous medium and a surfactant.
The dispersion is subjected to a high-pressure homogenizer, the granular mixture is refined to form fine particles having an average particle size smaller than the average particle size of the granular mixture, and the dispersion containing the fine particles is stirred. It comprises a step of agglomerating the fine particles while stirring in the part to form aggregated particles.

  When the present invention is used, stable atomization is possible, and thus toner particles having a smaller particle diameter and a more uniform composition can be easily obtained.

It is a flowchart showing an example of the manufacturing method of the developer concerning a 1st viewpoint. It is the schematic showing an example of a structure of a high voltage | pressure type homogenizer. It is a flowchart showing an example of the manufacturing method of the developing agent concerning the 2nd viewpoint.

  The developer producing method according to the first aspect of the present invention includes a step of preparing a dispersion by mixing a granular mixture of toner material containing a binder resin with an aqueous medium, and the resulting dispersion is a high-pressure type. Using a homogenizer, the granular mixture is refined to form fine particles having an average particle size smaller than the average particle size of the granular mixture, and the dispersion containing the fine particles is agglomerated while stirring in the stirring unit. A method including a step of forming aggregated particles, wherein a surfactant is further mixed into the dispersion, and the surface tension of the dispersion is adjusted to 50 mN / m or more.

  When a dispersion having such a surface tension is used, clogging can be prevented from occurring in the nozzle and check valve of the high-pressure homogenizer, and atomization can be performed stably. This also makes it possible to form toner particles with a uniform composition and reduced particle size.

  Further, in the developer manufacturing method according to the second aspect of the present invention, a release agent can be further added to the toner material in the developer manufacturing method according to the first aspect of the present invention. In addition, since the release agent acts as a lubricant in the nozzle and the check valve, stable atomization can be performed if the surface tension of the dispersion is 40 mN / m or more.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a flowchart showing an example of a developer manufacturing method according to the first aspect of the present invention.

  As shown in the figure, in this developer manufacturing method, first, at least a binder resin is prepared as a toner material, and a granular mixture is prepared (Act 1).

  As the binder resin, here, for example, a polyester resin having excellent fixability is used.

  The granular mixture is obtained, for example, by a step of melting and kneading a mixture containing a binder resin and a colorant. Alternatively, it can be obtained by granulating a binder resin or a mixture containing a binder resin and a colorant.

  When melt-kneading is performed, the colorant can be uniformly dispersed in the binder resin. The twin-screw extruder and roll mill are strong and are suitable for dispersing colorants. Dispersing in a resin with a high viscosity is more effective than dispersing in a low-viscosity material such as water. easy. When the binder resin is atomized without using a colorant or the like, it is not necessary to perform melt kneading. Instead of mixing the colorant into the toner material during melt kneading, for example, after atomization, a solution in which the colorant is dispersed can be mixed into the dispersion.

  The average particle size of the granular mixture can be 10 to 100 μm.

  With this particle size, it is possible to avoid clogging of the high pressure type homogenizer with the reversely supported valve. When it exceeds 100 μm, clogging at the reverse-support valve tends to become remarkable. On the other hand, if the thickness is less than 10 μm, the surface area of the system increases, so that it becomes easy to cause bubble clogging.

  Next, the granular mixture is mixed with a surfactant and an aqueous medium to form a dispersion having a surface tension of 50 mN / m or more (Act 2).

  A preferred range of surface tension is 50 to 73 mN / m.

  This dispersion is aqueous, and the upper limit of the surface tension of the dispersion does not exceed the surface tension of water of 73 mN / m.

  The optimum value of the surface tension is determined by the compatibility between the processed material and the member used for the check valve. For example, when the polyester resin is treated with a stainless counter valve, the optimum value is 50 mN / m. If the surface tension is less than the optimum value, the processed product will be wetted too much by the check valve member, and when passing through the check valve, it will stick due to friction inside the check valve. Therefore, by setting the surface tension to be equal to or greater than the optimum value, the sticking is eliminated and the clogging at the reverse valve can be improved. As a result, the fine particles can be stably produced.

  In the present invention, a pH adjusting agent can be added to the dispersion to adjust the pH to alkali. By adjusting the pH to the alkali side, atomization of a resin having an acid value such as a polyester resin is promoted. The alkali adjustment of the dispersion may be performed simultaneously with the preparation of the dispersion, but when the dispersion is left under alkali, for example, when a binder resin having an ester bond or a combination of surfactants is used, Since it may hydrolyze, it is desirable to carry out immediately before using it for a high-pressure homogenizer.

  When a surfactant is added to the dispersion, a toner component having a low affinity for water can be dispersed in an aqueous medium. As the surfactant to be used, those having good wettability to the toner component can be selected. This surfactant may be used in combination of several kinds.

  If necessary, the dispersion can be degassed.

  Defoaming is performed in order to avoid clogging at the back valve of the high-pressure homogenizer. Defoaming is effective in removing foam generated when the granular mixture is mixed with a surfactant and an aqueous medium. As a defoaming method, for example, the dispersion can be stirred under reduced pressure.

  The obtained dispersion is subjected to a high-pressure homogenizer and atomized (Act 3).

  This is a step of atomization at high temperature and pressure. High-pressure homogenizer has high atomization ability. In the case of atomization at 100 ° C. or higher, it is necessary to provide a cooling part after the atomization part. The cooling is further preferably lowered to a temperature below the Tg of the binder resin. An apparatus having a pressure reducing part or a back pressure part before and after the cooling part has particularly high atomization ability. In this step, desired toner particles may be formed by a series of high-pressure homogenizer treatments.

  FIG. 2 is a schematic diagram showing an example of the configuration of the high-pressure homogenizer used in the present invention.

  As shown in the figure, the high-pressure homogenizer 10 has a configuration in which a hopper tank 1, a liquid feed pump, a high-pressure pump 3, a heating unit 4, a atomization unit 5, a decompression unit 6, a cooling unit 7, and a decompression unit 8 are arranged in this order. And pipes that connect each part.

  The hopper tank 1 is a tank into which a processing liquid is charged. When the apparatus is in operation, it is necessary to always fill the liquid so as not to send air into the apparatus. In the case where the treatment liquid has a large particle size and a sedimentation property, a stirrer can be further provided.

  The liquid feed pump 2 is installed to continuously send the processing liquid to the high-pressure pump 1. It is also effective for avoiding clogging with a check valve (not shown) provided in the high-pressure pump 3. As the pump 2, for example, a diaphragm pump, a tubing pump, a gear pump, or the like can be used.

  The high-pressure pump 3 is a plunger type pump, and has check valves at the processing liquid inlet and the processing liquid outlet, although not shown. The number of plungers is 1 to 10 depending on the production scale. In order to reduce the pulsating flow as much as possible, two or more are desirable. The check valve is preferably made of stainless steel, and if it is made of stainless steel, there is an advantage that sticking of the processed material can be minimized.

  The heating unit 4 is provided with a high-pressure pipe 9 formed in a spiral shape in order to increase the heat exchange area in a heating apparatus such as an oil bath. The heating unit 4 has no problem on the upstream side or the downstream side of the high-pressure pump 3 with respect to the flow direction of the dispersion liquid, but it needs to be at least upstream of the atomization unit 5. When the heating unit 4 is installed on the upstream side of the high-pressure pump 3, a heating device may be provided to the hopper 1, but since the residence time at a high temperature is long, hydrolysis of the binder resin is likely to occur.

  The atomizing portion 5 includes a nozzle having a minute diameter for applying a strong shear. There are various nozzle diameters and shapes, but the nozzle diameter is desirably 0.05 mm to 0.5 mm, and the shape is desirably a pass-through nozzle or a collision nozzle. In addition, this nozzle may be composed of multiple stages, and in the case of multiple stages, a plurality of different nozzle diameters may be arranged. The method of arranging a plurality may be parallel or serial. The nozzle material is diamond or the like that can withstand high pressure.

  The cooling unit 7 is provided with a pipe 11 that is formed in a spiral shape in order to increase the heat exchange area in a bath in which cold water flows continuously. Here, the atomization part 5 and the cooling part 7 are arranged in series. As a result, there is an effect of cooling the processed product heated to 100 ° C. or more to less than 100 ° C.

  If necessary, decompression units 6 and 8 can be provided before and after the cooling unit 7. As a configuration of the decompression units 6 and 8, one or more cells or channels having a flow path larger than the nozzle diameter of the atomization unit 7 and smaller than the connection pipe diameter are arranged.

  The treatment with this high pressure homogenizer can be carried out as follows.

  First, priming water is filled in the high-pressure homogenizer.

  Next, the processing liquid is put into a hopper and atomization processing is performed.

First, the treatment liquid is heated to a glass transition temperature Tg or higher of the binder resin. The reason for heating is to melt the binder resin.

  This heating temperature varies depending on the melting characteristics of the binder resin. Resins that are easily melted are satisfactory even at low temperatures, but resins that are difficult to melt require high temperatures. Further, in the case of the method of heating by passing through the heat exchanger continuously, the flow rate of the dispersion and the length of the heat exchange pipe are also affected. When the flow rate is fast or when the piping is short, a high temperature is required. Conversely, when the flow rate is slow or when the piping is long, the dispersion is sufficiently heated, so that the treatment can be performed at a low temperature. When the flow rate is 300 to 400 cc / min, the heat exchange pipe is 3/8 inch and 12 m high pressure pipe, the binder resin Tg is 60 ° C., and the toner softening point Tm is 130 ° C., the heating temperature is 100 ° C. to 200 ° C. Good. The heating temperature is preferably in the range of 150 ° C. higher than the glass transition temperature Tg to Tg. When the heating temperature is too high, the binder resin tends to be hydrolyzed. When the heating temperature is about Tg to Tg + 150 ° C., there is no problem that the fixing property is deteriorated.

  The softening point of the toner is measured by the temperature rising method of a flow tester CFT-500 manufactured by Shimadzu Corporation, and the point on the curve corresponding to 2 mm of the plunger lowering amount is defined as the softening point from the flowchart.

  Next, the heated dispersion is sheared while applying a pressure of 10 MPa or more. At this time, it is the nozzle that gives the shear. The molten toner component is atomized by passing through the nozzle while applying a high pressure of 10 MPa or more. The pressure at this time is preferably 10 MPa to 300 MPa.

  Finally, cool to below Tg. By this cooling, the melted fine particles are solidified. Since the processing liquid is rapidly cooled, aggregation and coalescence due to cooling are less likely to occur.

  If necessary, a back pressure may be applied before or after the cooling unit, or a reduced pressure may be applied. Back pressure or reduced pressure means that atmospheric pressure is not released immediately after passing through the nozzle, but is returned to near atmospheric pressure in one stage (back pressure) or multiple stages (reduced pressure). The pressure after passing through the back pressure part or the decompression part is 0.1 MPa to 10 MPa, preferably 0.1 to 5 MPa. It is further preferable that the decompression unit has a plurality of cells or valves having different diameters. By reducing the pressure in multiple stages, fine particles having an average particle size of 2 μm or less with few coarse particles and a sharp particle size distribution can be obtained.

  Subsequently, the fine particles in the dispersion taken out from the high-pressure homogenizer are aggregated (Act 4).

  In the aggregation process, the obtained fine particles are aggregated to a desired toner particle size as necessary. After aggregation, for example, the toner is obtained by heating to a Tg of the binder resin or more and fusing the particles together. The agglomeration and fusion may be performed in a cooling unit and a decompression unit connected to a high-pressure homogenizer, or may be performed in another apparatus after being cooled once. Moreover, this aggregation and fusion may proceed simultaneously.

  Thereafter, the resin fine particles can be heteroaggregated on the surface of the aggregated particles to be encapsulated. The resin fine particles used for encapsulation may be prepared by mechanical shearing force, or may be prepared by emulsion polymerization or the like. Further, toner particle formation and capsule formation may be performed simultaneously.

  Thereafter, the process of adding ion-exchanged water to the aggregated particles for washing and filtering is repeated, and the filtrate is washed until the conductivity of the filtrate reaches 50 μS / cm (Act 5).

  Next, the washed agglomerated particles are dried with a vacuum dryer until the water content becomes 1.0% by weight or less (Act 6) to obtain toner particles.

  Further, if necessary, external additives such as hydrophobic silica 2 and titanium oxide are adhered to the toner particles as additives, to obtain a desired toner.

FIG. 3 is a flow chart showing an example of a developer manufacturing method according to the second aspect of the present invention. In this developer manufacturing method, at least a binder resin and a release agent are prepared as toner materials, and granular. Except for preparing a mixture of (Act 1 ′) and mixing the particulate mixture with a surfactant and an aqueous medium to form a dispersion having a surface tension of 40 mN / m or more (Act 2 ′). The configuration is the same as in FIG.

  In this case, it is preferable that the reverse support valve used for the high-pressure homogenizer is made of stainless steel, and the toner material contains a binder resin made of a polyester resin.

  In the developer manufacturing method according to the second aspect of the present invention, a release agent such as wax acts as a lubricant with the check valve member. Therefore, even when the surface tension of the dispersant is reduced to 40 mN / m, the high-pressure homogenizer Clogging at the check valve and nozzle is less likely to occur.

  A preferable surface tension in the method according to the second aspect is 40 to 73 mN / m.

  According to the present invention, high-performance toner particles can be stably produced in a method of obtaining toner by agglomerating a granular mixture of toner materials with a high-pressure homogenizer and then aggregating the mixture. When a high-pressure homogenizer is used, the particles can be atomized by passing them through the pores under high pressure. When the particles contain a thermoplastic resin, the resin is heated to a temperature equal to or higher than the Tg of the resin to melt the resin. Thus, atomization can be performed without using a solvent. However, the high-pressure homogenizer is difficult to handle because it tends to cause clogging in the reverse-support valve used for producing high pressure and in the nozzle. On the other hand, by using the method of the present invention, it is possible to eliminate the clogging in the reversely supported valve or the pipe and to manufacture stably.

(Coloring agent)
Examples of the colorant used in the present invention include carbon black, organic or inorganic pigments and dyes. For example, carbon black includes acetylene black, furnace black, thermal black, channel black, ketjen black, and the like. Examples of yellow pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 74, 81, 83, 93, 95, 97, 98, 109, 117, 120, 137, 138, 139, 147, 151, 154, 167, 173, 180, 181, 183, 185, C.I. I. Bat yellow 1, 3, 20, etc. are mentioned. These may be used alone or in combination. Examples of magenta pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 150, 163, 184, 185, 202, 206, 207, 209, 238, C.I. I. Pigment violet 19, C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35, etc. are mentioned. These may be used alone or in combination. Examples of cyan pigments include C.I. I. Pigment blue 2, 3, 15, 16, 17, C.I. I. Bat Blue 6, C.I. I. Acid Blue 45 and the like. These may be used alone or in combination.

  In the granular mixture, at least one of a wax and a charge control agent can be further added.

(Release agent)
Examples of the wax include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and aliphatic hydrocarbon waxes such as oxidized polyethylene wax. Oxide of wax or block copolymer thereof, candelilla wax, carnauba wax, wood wax, jojoba wax, plant wax such as rice wax, beeswax, animal wax such as lanolin, whale wax, ozokerite, ceresin Mineral waxes such as petrolatum, montanic ester waxes, waxes based on fatty acid esters such as castor wax, and fatty acid esters such as deoxidized carnauba wax. The other is exemplified such as those de-oxidation all. Further, saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkyl carboxylic acids having a long-chain alkyl group, unsaturated fatty acids such as brassic acid, eleostearic acid, parinaric acid, stearyl alcohol , Saturated alcohols such as eicosyl alcohol, behenyl alcohol, carnauvir alcohol, seryl alcohol, melyl alcohol, or long chain alkyl alcohols having a long chain alkyl group, polyhydric alcohols such as sorbitol, linoleic acid amide, oleic acid Amide, fatty acid amide such as lauric acid amide, methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, saturated fatty acid bis amide such as hexamethylene bis stearic acid amide, Unsaturated fatty acid amides such as lenbis oleic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide, m-xylene bis stearic acid amide, Aromatic bisamides such as N, N'-distearylisophthalic acid amide, fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally referred to as metal soap), aliphatic Hydroxyl obtained by hydrogenating waxes grafted to hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid, partially esterified products of fatty acids and polyhydric alcohols such as behenic acid monoglycerides, and vegetable oils and fats. Methyl Este Having a Group Compounds.

(Charge control agent)
As the charge control agent for controlling the triboelectric charge amount, for example, a metal-containing azo compound is used, and the metal element is preferably a complex, complex salt of iron, cobalt, chromium, or a mixture thereof. In addition, a metal-containing salicylic acid derivative compound can be used, and the metal element is preferably a complex, complex salt of zirconium, zinc, chromium, boron, or a mixture thereof.

(Surfactant)
Examples of the surfactant that can be used in the present invention include anionic surfactants such as sulfate ester, sulfonate, phosphate, and soap, amine salt type, quaternary ammonium salt type, and the like. Nonionic surfactants such as cationic surfactants, polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols can be mentioned. Anionic surfactants are desirable from the viewpoint of atomization of polyester resins. . Further, from the viewpoint of dispersion stability, it is desirable to obtain an optimum surface tension value at a concentration equal to or higher than the critical micelle concentration. Specifically, sodium alkane (C _{12 to} C ₁₄ ) sulfonate, alkenyl (C _{12 to} C ₁₄₎ dipotassium succinate is preferable. These surfactants may obtain a desired surface tension singly or in combination of two or more.

  As the addition amount of the surfactant, it can be added so that the surface tension of the dispersion becomes higher than the optimum value.

(Surface tension measuring device)
The surface tension measuring device is not particularly limited, but can be measured by a measuring device to which a general surface tension measuring method such as a dropping number method or a Wilhelmy plate method is applied.

(PH adjuster)
Although it does not restrict | limit especially as a pH adjuster which can be used for this invention, For example, in addition to sodium hydroxide, potassium hydroxide, etc., an amine compound can be used. Examples of amine compounds include dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, sec-butylamine, monoethanolamine, diethanolamine, triethanolamine, triisopropanolamine. , Isopropanolamine, dimethylethanolamine, diethylethanolamine, N-butyldiethanolamine, N, N-dimethyl-1,3-diaminopropane, N, N-diethyl-1,3-diaminopropane and the like. From the viewpoint of improving the self-dispersibility of the polyester resin and the performance, the pH adjuster is particularly preferably an organic amine compound.

(High-pressure homogenizer)
Examples of the high-pressure homogenizer of the present invention include NANO3000 (beautiful grains), Nanomizer (Yoshida Kikai Kogyo), Starburst (Sugino Machine), Microfluidizer (Mizuho Industry), Homogenizer (Sanwa Machine) and the like.

(Kneading machine)
In the present invention, in order to prepare a granular mixture, a mixture containing at least a binder resin and a colorant can be kneaded.

  The kneader to be used is not particularly limited as long as melt kneading is possible, and examples thereof include a single screw extruder, a twin screw extruder, a pressure kneader, a Banbury mixer, and a Brabender mixer. Specifically, FCM (made by Kobe Steel), NCM (made by Kobe Steel), LCM (made by Kobe Steel), ACM (made by Kobe Steel), KTX (made by Kobe Steel), GT (manufactured by Ikegai Co., Ltd.), PCM (manufactured by Ikegai Co., Ltd.), TEX (manufactured by Nippon Steel Works Co., Ltd.), TEM (manufactured by Toshiba Machine Co., Ltd.), ZSK (manufactured by Warner Company), and Nidex (manufactured by Mitsui Mining Company) It is done.

(External additive)
In the present invention, in order to adjust fluidity and chargeability with respect to the toner particles, 0.01 to 20% by weight of inorganic fine particles may be added and mixed with the toner particle surface with respect to the total weight of the toner. As such inorganic fine particles, silica, titania, alumina, strontium titanate, tin oxide, cerium oxide or the like can be used alone or in admixture of two or more.

  The inorganic fine particles are preferably surface-treated with a hydrophobizing agent from the viewpoint of improving environmental stability. In addition to such inorganic oxides, resin fine particles having a size of 1 μm or less may be externally added to improve cleaning properties.

  As a mixer for inorganic fine particles, for example, Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), super mixer (manufactured by Kawata Co., Ltd.), ribocorn (manufactured by Okawara Seisakusho Co., Ltd.), nauter mixer (manufactured by Hosokawa Micron Co., Ltd.), turbulizer (Hosokawa Micron Co., Ltd.) Co., Ltd.), cyclomixer (manufactured by Hosokawa Micron Corporation), spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.), and Ladige mixer (manufactured by Matsubo).

  In the present invention, coarse particles and the like may be further screened. As the sieving equipment used for the sieve, Ultrasonic (manufactured by Sakae Sangyo Co., Ltd.), Gyroshifter (Tokuju Kogakusha Co., Ltd.), Vibrasonic System (manufactured by Dalton Co., Ltd.), Soniclean (manufactured by Shinto Kogyo Co., Ltd.), Turbo Screener (Manufactured by Turbo Kogyo Co., Ltd.), micro shifter (manufactured by Hadano Sangyo Co., Ltd.), circular vibrating sieve, etc.

Examples Hereinafter, the present invention will be specifically described with reference to Examples.

Preparation of Coarse Particle A Polyester resin (Mw: 13658, Tg: 58 ° C., Tm: 102 ° C.) 90 parts by weight Cyan pigment Copper phthalocyanine pigment (Toyo Ink Co., Ltd.) 5 parts by weight Rice wax 5 parts by weight or more were mixed Thereafter, the mixture was melt-kneaded in a biaxial kneader set at 110 ° C. to obtain a kneaded product.

  The obtained kneaded product was coarsely pulverized to an average volume particle size of 50 μm using a pulverizer manufactured by Hosokawa Micron Corporation to obtain coarse particles.

Example 1
30 parts by weight of the mixture coarse particles A, 0.3 parts by weight of sodium alkanesulfonate as a surfactant and 69.1 parts by weight of ion-exchanged water were mixed to obtain a dispersion.

  The dispersion was set in a desiccator equipped with a stirrer, and while gently stirring, the pressure was reduced to -0.09 MPa with a vacuum pump, and defoaming was performed for 10 minutes.

  0.6 parts by weight of dimethylaminoethanol as an alkaline pH adjuster was added to the defoamed dispersion to adjust the pH to 11.

  The surface tension of this dispersion was measured by adjusting the sample to a solid content concentration of 5 wt% using BP-D5 manufactured by Kyowa Interface Science Co., Ltd. and found to be 40 mN / m.

  Next, a hopper as a raw material charging unit, a 12 m heat exchange high-pressure pipe immersed in an oil bath as a heating unit, a stainless check valve, and a nozzle having 0.13 μm and 0.28 μm connected as a pressurizing unit are included. High-pressure piping, medium-pressure piping connected with cells having pore diameters of 0.4, 1.0, 0.75, 1.5, and 1.0 μm as the decompression section, and 12 m heat that can be cooled with tap water as the cooling section 400 cc of priming water was filled in the NANO 3000 where the exchange pipe was installed.

  In an apparatus filled with priming water, 1 liter of the coarse particle dispersion was put into a hopper, and atomized, decompressed and cooled continuously at 180 ° C. and 150 MPa to perform atomization. When a small amount of the obtained dispersion was extracted and the particle size of the fine particles obtained by SALD7000 manufactured by Shimadzu Corporation was measured, a sharp particle size distribution with a volume average particle size of 0.5 μm and a standard deviation of 0.13 was obtained. It was.

  10 parts by weight of the obtained finely divided dispersion and 90 parts by weight of ion-exchanged water were mixed, and 10 parts by weight of a 5% aluminum sulfate aqueous solution as a flocculant was added.

  The resulting dispersion was heated to 80 ° C. while stirring at a stirring speed of 500 rpm. Thereafter, 0.1 part by weight of dimethylaminoethanol was added and further heated to 85 ° C. to obtain aggregated fused particles. When the particle size was measured with Coulter Multisizer 3, it was found that the particle size distribution was sharp with a 50% volume average diameter Dv of 5 μm and a CV of 18.5%.

  The solid content of the dispersion containing the agglomerated fused particles was repeatedly filtered and washed with ion-exchanged water until the filtrate had a conductivity of 50 μS / cm. Thereafter, the toner was dried with a vacuum dryer until the water content became 1.0% by weight or less to obtain toner particles.

  After drying, as additives, 2 parts by weight of hydrophobic silica and 0.5 parts by weight of titanium oxide were adhered to the toner particle surface to obtain a desired toner.

  The obtained toner is put into a TOSHIBA TEC composite machine e-STUDIO 281c modified so that the fixing temperature can be controlled for evaluation, and an image is formed using an isolated point reproducibility test chart to evaluate the image quality. did.

  In this isolated point reproducibility test, images are drawn using a test chart on which a square of about 100 μm is drawn, and the image is evenly filled with an optical microscope, or toner dust is generated at the edge. Observe whether or not it is done and evaluate the image quality.

  As a result, the isolated point reproducibility of the obtained image was good.

Example 2
A polyester resin (Mw: 6500, Tg: 55 ° C., Tm: 105 ° C.) was pulverized to an average particle size of 50 μm using a pulverizer manufactured by Hosokawa Micron Co., Ltd. By doing so, fine particles were formed. The obtained dispersion containing fine particles is mixed with the dispersion containing aggregated particles obtained in Example 1, and 5 parts by weight of 5% ammonium chloride aqueous solution is added as an aggregating agent to cause heteroaggregation. Heating to 85 ° C. yielded aggregated fused particles.

  The solid content of the dispersion containing the obtained agglomerated fused particles was washed and dried in the same manner as in Example 1 to obtain toner particles. An external additive was added to the toner particles to obtain a toner.

  Similarly, as a result of evaluating the image quality, the image was good.

Comparative Example 1
A dispersant was prepared in the same manner as in Example 1 except that 0.3 part by weight of sodium dodecylbenzenesulfonate was added as a surfactant. Similarly, the surface tension was measured and found to be 35 mN / m.

  When atomization was performed in the same manner as in Example 1, particles having a broad particle size distribution with a volume average particle size of 1 μm were obtained.

  Further, when the obtained particles were aggregated in the same manner as in Example 1, toner particles having a broad particle size distribution with a volume average particle size of 6 μm were obtained.

  Similarly, as a result of evaluating the image quality, countless spots that seem to be derived from coarse particles were confirmed in the image.

Comparative Example 2
By using sodium lucan sulfonate as a surfactant, a dispersion having a surface tension of 40 mN / m was prepared and atomization was performed in the same manner as in Example 2. Fine particles could not be obtained.

Japanese Patent Laid-Open No. 63-282275 JP-A-6-250439 JP-A-9-311502 JP 2007-323071 A JP 2008-89670 A JP 2006-227592 A JP-A-2005-221968 JP 2000-292976 A

Claims (4)

Mixing a particulate mixture of toner materials containing a binder resin with an aqueous medium and a surfactant to prepare a dispersion having a surface tension of 50 mN / m or more;
The dispersion is subjected to a high-pressure homogenizer, the granular mixture is refined to form fine particles having an average particle size smaller than the average particle size of the granular mixture, and the dispersion containing the fine particles is stirred. A method for producing a developer, comprising a step of aggregating the fine particles while stirring in a part to form aggregated particles. A step of preparing a dispersion having a surface tension of 40 mN / m or more by mixing a granular mixture of a toner material containing a binder resin and a release agent with an aqueous medium and a surfactant;
The dispersion is subjected to a high-pressure homogenizer, the granular mixture is refined to form fine particles having an average particle size smaller than the average particle size of the granular mixture, and the dispersion containing the fine particles is stirred. A method for producing a developer, comprising a step of aggregating the fine particles while stirring in a part to form aggregated particles.   The method according to claim 1, wherein the toner material further contains a colorant, and the granular mixture is formed by melting and kneading the toner material and then pulverizing the toner material.   The method according to any one of claims 1 to 3, wherein the dispersion contains a pH adjusting agent, and the pH is alkaline.

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