JP4501753B2 - Method for producing toner for developing electrostatic image - Google Patents

Description

  The present invention relates to a method for producing a toner for developing an electrostatic charge image that is suitably used for a copying machine, a printer, a fax machine, and the like.

  In recent years, with changes in the usage environment, the colorization rate of copying machines, printers, etc. has been increasing year by year. At the same time, due to demands for high resolution and high gradation and high image quality, it is essential to improve uniformity by reducing the particle size of the toner and sharpening the distribution. Under such circumstances, in the toner production method, various toner production methods using a wet method such as an emulsification dispersion method or a polymerization method called a “chemical toner” are attracting attention from conventional pulverization methods. Among them, the emulsification dispersion method makes it easy to reduce the particle size and spheroidization of the toner, and the selection range of the binder resin is wider than the polymerization method, so that condensation of polyester resin or epoxy resin can be performed. Series resins can be used as the main binder resin. Therefore, it is possible to make use of advantages such as offset resistance in a wide area inherent to the resin, low-temperature fixability, and good heat-resistant storage stability by maintaining the glass transition temperature.

  As a conventional technique relating to a toner production method using an emulsification dispersion method, for example, a colorant and a polyester resin that becomes an anionic self-water-dispersible resin are dispersed in an organic solvent, and then subjected to phase inversion emulsification. A method for producing particles is disclosed (for example, see Patent Document 1). Furthermore, a method for producing a toner having a sharp particle size distribution in a high yield by dispersing a colorant and a polyester resin in an organic solvent, then performing phase inversion emulsification, and then performing a coalescing step is disclosed. (For example, refer to Patent Document 2).

  However, in the emulsification dispersion method, a hydrophobic organic solvent is used to dissolve or suspend the polyester resin, which is a binder resin, to adjust the organic layer, and then to form particles in an aqueous medium. The toner particles (hereinafter referred to as colorant-containing resin particles) contain an organic solvent. In this production method, particles are formed in an aqueous medium, then the solvent is removed, a part of the hydrophobic organic solvent contained in the aqueous medium is removed, solid-liquid separation and washing are performed, and the obtained water content is obtained. It is necessary to remove moisture and remaining hydrophobic organic solvent from the colorant-containing resin particles in the drying step. Since the solvent remains in the colored resin particles and the glass transition temperature is lowered, a fusion product is generated when the drying temperature is raised. Therefore, low temperature drying is an essential condition in this production method.

  Examples of drying methods in the drying process include removal of residual monomers such as moisture and volatile organic substances using a dryer equipped with a stirrer that can be decompressed, such as Ribocorn (Okawara Seisakusho) and Nauta Mixer (Hosokawa Micron). It is disclosed (for example, see Patent Documents 3 to 6). When drying the water-containing colorant-containing resin particles using the dryer, since it is an indirect heating method with a heat transfer surface, the heat transfer area of the resin particles charged in the vacuum vessel when scaled up There is a demerit that the ratio decreases as the scale becomes larger, and drying for a long time is required when removing moisture. In addition, in order to shorten the drying time in the drying method using the mixed vacuum method, a method of removing moisture in advance using a fluidized bed or a flash jet dryer (Seishin company), etc. before entering the vacuum drying, or a carrier gas delivery Alternatively, a method of removing the volatile component staying by adjusting the temperature of the carrier gas is also disclosed (see, for example, Patent Documents 3 to 6), but in order to remove the organic solvent remaining in the particles to a low level, It takes a long time. On the other hand, a drying method using a fluidized bed using a dry airflow is also disclosed (for example, see Patent Documents 7 to 10). Drying with a fluidized bed performs direct heat exchange with a hot air stream, so it can efficiently remove moisture, but the temperature cannot be raised, so the organic solvent remaining in the particles must be removed above a certain level. I can't.

In all of the above-described disclosed drying methods, water is removed first, and then the remaining volatile organic substances are removed. However, the boiling point under normal pressure is lower than that of water, and the hydrophobicity has a high affinity with the binder resin. There is a limit to efficiently removing the organic solvent. This is presumably because the removal of water blocks the microscopic passages on the particle surface and inhibits the removal of the organic solvent.
As a method for solving the above problem, there is a drying method in which a fluidized bed is formed using a mechanical vibration and a conditioned air stream, an organic solvent is first removed in an equilibrium water-containing state, and then moisture is removed under a dry air stream. It is disclosed (for example, see Patent Document 11).

  In the fluidized bed, air is blown into the granular material, the solid particles are suspended and suspended, and dried in a state similar to a fluid (jet properties). The conventional fluidized bed has a limit on the size of the powder in order to ensure fluidity by the air volume. Only air volume prevents aggregation between the powders, and efficient drying is not possible. In the fluidized bed of this publication, a vibration system is introduced, and fluidization is performed by “vibration + air volume”. Due to the synergistic effect of both, a stable fluidized bed can be secured and fluidization can be achieved with a smaller amount of air. As a result, a more uniform “solid-gas” contact is possible and drying efficiency is improved.

In the fluidized bed of this publication, an efficient organic solvent removal process is constructed by combining fluidization by “vibration + air volume” and an organic solvent component entrainment effect by “humidified air”. By the way, in the fluidized bed, the organic solvent is first removed by the conditioning air in a humid environment, and then the moisture is removed by the dry air. The moisture removal efficiency by the dry air is also higher than that of a normal fluidized bed due to the above characteristics. It is presumed to be good.
JP-A-8-21655 JP 2002-287424 A JP 11-295927 A JP 2001-235900 A Japanese Patent Application Laid-Open No. 2004-117782 Japanese Patent Laid-Open No. 2002-6552 JP-A-8-179562 Japanese Patent Laid-Open No. 11-344831 JP 2000-330335 A JP 2004-226445 A Japanese Patent No. 03439796

  However, in patent document 11, it is limited to the removal of the organic solvent mainly used at the time of crystallization regarding a foodstuff or a pharmaceutical, or the organic solvent used for washing | cleaning. The organic solvent used is mainly a water-soluble organic solvent such as methanol or acetone, and has no solubility in the material to be dried. On the other hand, information on hydrophobic organic solvents that can dissolve and suspend resins, have high affinity between resins and organic solvents, and have low solubility in water, such as those used in emulsification dispersion methods, and coloring No information is disclosed regarding the removal of the hydrophobic organic solvent encapsulated in the resin particles containing the agent. In addition, when the hydrophobic organic solvent remains in the particles obtained by the emulsification dispersion method, it is easy to be fused even at a low temperature due to the plasticizing effect of the solvent. A plurality of particles tend to agglomerate with each other by the film, so that there is a problem that a fusion material is finally mixed. That is, in this method, the occurrence of the fused product due to the aggregation cannot be prevented, and the level is still not satisfactory for achieving good image quality as a toner. Further, due to the expansion of the layer due to fluidization, the volume of the material to be dried expands, so that the amount of preparation is limited and the productivity is lowered.

  The present invention has been made in view of the above circumstances, and its object is to prepare a hydrophobic organic solvent, a colorant, and an organic layer containing a polyester resin as a binder resin, and then a particle forming step in an aqueous medium. In the process for producing a toner for developing an electrostatic image obtained through the process, a novel method for efficiently removing moisture and a hydrophobic organic solvent from the obtained water-containing colorant-containing resin particles or from the surface of the water-containing colorant-containing resin particles It is to provide a manufacturing method. Another object of the present invention is to provide a novel production method for producing a toner for developing an electrostatic image that has no fused product in the drying step and has excellent development characteristics.

  As a result of intensive research, the present inventors first used a dryer equipped with a stirrer that can be depressurized, from among the water-containing colorant-containing resin particles obtained in a wet manner, first under mechanical stirring by a stirrer. The present inventors have found that moisture and a used hydrophobic organic solvent can be efficiently removed and that generation of a fused product can be prevented by continuously supplying a humidity control gas at normal pressure and then performing vacuum drying under reduced pressure.

That is, the present invention is colored by emulsifying or suspending a mixture containing a binder resin mainly composed of a polyester resin, a colorant, and a hydrophobic organic solvent capable of dissolving or dispersing the polyester resin in an aqueous medium. A first step of obtaining a water-containing colorant-containing resin particle by washing and dehydrating the colorant-containing resin particle as a suspension of the agent-containing resin particle,
Next, the water-containing colorant-containing resin particles are put into a dryer equipped with a stirrer that can be depressurized, and a gas (I) whose relative humidity is adjusted to 70 to 100% while stirring with the stirrer under normal pressure. ), And the hydrophobic organic solvent remaining in the water-containing colorant-containing resin particles is removed by moisture contained in the gas (I), and then the water-containing colorant-containing resin particles or the water-containing color is removed. This is a method for producing a toner for developing an electrostatic charge image, in which the second step of removing the water remaining on the surface of the agent-containing resin particles under reduced pressure with stirring is sequentially performed.

  According to the production method of the present invention, from the surface of the water-containing colorant-containing resin particles or the water-containing colorant-containing resin particles containing a hydrophobic solvent having a high affinity with the polyester resin as the binder resin, It is possible to produce a toner for developing an electrostatic charge image, in which an organic solvent and moisture are efficiently and greatly reduced, and there is no generation of a fused product.

Hereinafter, a method for producing an electrostatic image developing toner according to the present invention will be described. The manufacturing method of the present invention includes the following first step and second step.
First step: A colorant is contained by emulsifying or suspending a mixture containing a binder resin mainly composed of a polyester resin, a colorant, and a hydrophobic organic solvent capable of dissolving or dispersing the polyester resin in an aqueous medium. A suspension of resin particles is obtained, and the colorant-containing resin particles are washed and dehydrated to obtain water-containing colorant-containing resin particles.
Second step: The water-containing colorant-containing resin particles in a dryer (with a stirrer that can be depressurized) are mixed with a gas whose relative humidity is adjusted to 70 to 100% under mechanical stirring at normal pressure (I ) To replace the hydrophobic organic solvent remaining in the water-containing colorant-containing resin particles with the moisture of the gas (I), and then remove the remaining water under reduced pressure under mechanical stirring. Particles
(1) Fine particles of a hydrophobic organic solvent in which a colorant and a polyester resin are dissolved or dispersed,
(2) emulsified fine particles in a state where a polyester resin dissolved in an aqueous medium is attached to fine particles of a colorant;
Or
(3) It may be any fine particle in the form of emulsified fine particles in which a microemulsion of a polyester resin swollen by a hydrophobic organic solvent is adhered to the fine particles of the colorant, or a mixed fine particle of those forms.
When the toner is produced by the coalescence method described later, it is preferable to produce a suspension of the colorant-containing resin particles in the state (2) or (3).

First, the first step will be described in detail. In the first step, first, a binder resin containing a polyester resin as a main component and a colorant are introduced into a hydrophobic organic solvent and dissolved or dispersed to prepare a mixture (step 1-i). If necessary, a release agent and other additives can be used together with the mixture, but in any case, it is necessary to be finely dispersed or dissolved below the toner particle diameter.
The binder resin and the colorant are preferably dissolved or dispersed in the hydrophobic organic solvent with a high-speed stirrer. In this case, additives such as a release agent may be mixed after separately preliminarily dispersing in advance to adjust the master kneading chip. In the first step, a high-speed stirrer such as DESPA (Asada Iron Works Co., Ltd.) or Homomixa (Special Machine Industries Co., Ltd.) can be used. The blade tip speed at this time is preferably 4 to 30 m / s, particularly preferably 10 to 25 m / s. By using the high-speed stirrer, the binder resin can be efficiently dissolved in the hydrophobic organic solvent, and uniform fine dispersion of the colorant in the binder resin solution can be achieved. That is, the state of the colorant finely dispersed in advance can be maintained in the binder resin solution by stirring at high speed. When the blade tip speed is lower than 4 m / s, the fine dispersion of the colorant in the binder resin solution becomes insufficient, which is not preferable. On the other hand, if it is higher than 30 m / s, heat generation due to exclusive cutting becomes large, and it is not preferable because uniform stirring becomes difficult in combination with volatilization of the solvent. Moreover, the temperature in the case of melt | dissolving or disperse | distributing has the preferable range of 20-60 degreeC, and the range which is 30-50 degreeC is especially preferable.

  As a hydrophobic organic solvent, it is preferable that the solubility with respect to water in 25 degreeC is 0.1-30 mass%, and it is especially preferable that it is 0.1-25 mass%. Moreover, it is preferable that the boiling point in a normal pressure is lower than the boiling point of water. Examples of such a hydrophobic organic solvent include ketones such as methyl ethyl ketone and methyl isopropyl ketone, and esters such as ethyl acetate and isopropyl acetate. These hydrophobic organic solvents can be used in combination of two or more, but from the viewpoint of solvent recovery, it is preferable to use the same type of solvent alone. The hydrophobic organic solvent is preferably a solvent having a low boiling point because it dissolves or disperses the polyester resin, has a relatively low toxicity, and is easy to remove the solvent in a later step. Here, as the organic solvent for dissolving the polyester resin, methyl ethyl ketone and ethyl acetate, which are excellent in solubility and dispersibility, are used. In particular, it is most preferable to use methyl ethyl ketone.

  Next, the obtained mixture is emulsified or suspended in an aqueous medium to prepare a suspension of colorant-containing resin particles (step 1-ii). Preferably, the mixture is suspended or dissolved by mixing with water in the presence of a basic neutralizing agent, which is a basic compound, to prepare a suspension of colorant-containing resin particles (fine particles (A)). Here, it is preferable to gradually add water to the colorant-containing resin liquid in which the carboxyl group of the polyester resin is neutralized with the base of the basic compound. 50: 50-80: 20 is preferable and, as for the ratio of water and the organic solvent after finishing dripping water, 60: 40-80: 20 is more preferable.

The polyester used in the present invention preferably has a carboxyl group. If it is a polyester resin having a carboxyl group, it is easily dispersed in water by neutralizing the carboxyl group (hereinafter referred to as self-water dispersibility) or becomes water-soluble. Further, the acid value of the self-water dispersible or water-soluble polyester resin is preferably 1 to 30 KOHmg / g, and more preferably 3 to 20 KOHmg / g.
This is because when the acid value of the polyester resin is less than 1, production of an aqueous solution in which the polyester resin and the organic solvent are uniformly dissolved or mixed with water, or suspension of fine particles of the polyester resin and the organic solvent suspended in water. Since the suspension is not smoothly produced and coarse particles are generated, it is not preferable.
On the other hand, when the acid value of the polyester resin is greater than 30, the charge amount under various environments is not stable, which is not preferable. The polyester resin having an acid value of 1 to 30 KOHmg / g becomes an anionic type by neutralizing the carboxyl group with a basic compound. As a result, the hydrophilicity of the resin increases, and the resin can be stably dispersed or dissolved without using a dispersion stabilizer or a surfactant.

  The basic compound for neutralization is not particularly limited, and for example, inorganic bases such as sodium hydroxide, potassium hydroxide and ammonia, and organic bases such as diethylamine, triethylamine and isopropylamine are used. In particular, inorganic bases such as ammonia, sodium hydroxide, and potassium hydroxide are preferred. In order to disperse the polyester resin in water or in a medium containing water as a main component and containing an organic solvent (aqueous medium), there is a method of adding a dispersion stabilizer such as a suspension stabilizer or a surfactant. A high shear force is required in the method of emulsifying by adding a turbid stabilizer or a surfactant. This is not preferable because the generation of coarse particles and the particle size distribution become broad. Further, in the case of a cross-linked polyester resin containing a gel content, the particle size distribution becomes more non-uniform, and there is a practical limit. Therefore, in the present invention, a self-dispersible or water-soluble polyester resin is used, and the carboxyl group of the polyester resin is neutralized with a basic compound.

  As a method for neutralizing the carboxyl group of the polyester resin with the base of the basic compound, for example, (1) after producing a mixture containing a polyester resin having a carboxyl group, an organic pigment, a release agent, an organic solvent, and the like, A method of neutralizing with a base, (2) A basic neutralizing agent is mixed in advance in water or an aqueous medium, and the acidic group of the polyester resin contained in the mixture is neutralized when performing the second step. The method etc. are mentioned.

  Here, the amount of the basic compound used is preferably an amount corresponding to 1 to 3 times the amount necessary for neutralizing all carboxyl groups of the polyester resin, and is an amount corresponding to 1 to 2 times. It is more preferable. By adding in excess of the amount required to neutralize the carboxyl groups of the polyester resin in this way, it is possible to prevent the formation of irregularly shaped particles and sharpen the particle size distribution in the coalescence process. can do.

  In step 1-ii, a high-speed stirrer such as DESPA (Asada Iron Works Co., Ltd.), Homomixa (Special Machine Industries Co., Ltd.) or Slasher (Mitsui Mining Co., Ltd.), Cavitron (Eurotech Co., Ltd.), or high-speed dispersion The machine can be used. The blade tip speed at this time is preferably 4 to 30 m / s, and particularly preferably 10 to 25 m / s. By using the high-speed stirrer or the high-speed disperser, a suspension of the mixture in the aqueous medium can be efficiently obtained, and uniform fine dispersion of the colorant contained in the mixture in the aqueous medium can be achieved. That is, the state of the colorant finely dispersed in Step 1-i in advance can be maintained in an aqueous medium by high-speed stirring. When the blade tip speed is lower than 4 m / s, the fine dispersion of the colorant in the aqueous medium becomes insufficient, which is not preferable. On the other hand, if it is higher than 30 m / s, it is not preferable because scattering tends to be intense and insoluble matter tends to be mixed. The temperature at that time is not particularly limited, but a high temperature is not preferable because the amount of phase inversion water increases. On the other hand, if the temperature is low, the viscosity of the mixture containing the polyester resin and the organic solvent is increased, and the generation of coarse particles is increased. Moreover, as a temperature range of process 1-ii, it is preferable that it is 20 to 60 degreeC, and it is especially preferable that it is 20 to 50 degreeC.

Next, a dispersion stabilizer is added to the suspension, and then an electrolyte is added to produce the combined (B) of the colorant-containing resin particles (fine particles (A)) (step 1-iii).
In the coalescence method, a suspension of colorant-containing resin particles (fine particles (A)) is diluted with water to adjust the amount of solvent, and then a dispersion stabilizer is added. And unity is advanced by dripping the aqueous solution of electrolyte in presence of a dispersion stabilizer, and unity is obtained. By adding an electrolyte to the suspension of the fine particles (A), the fine particles are salted out or destabilized, and further, the coalescence proceeds by integrating the plurality of fine particles, whereby the coalescence can be obtained. By adding the electrolyte, not only the fine particles (A) are united, but also the polyester resin dissolved in the aqueous medium is salted out or destabilized to precipitate the fine particles of the polyester resin, The fine particles (A) are directly adhered to the surface of the fine particles (A) or the already-integrated fine particles (A), or the polyester resin dissolved in the aqueous medium is salted out or destabilized to directly form fine particles ( By adhering to the surface of A) or the coalesced fine particles (A) that have already coalesced, coalescence proceeds to obtain the coalesced.

  The suspension of fine particles (A) obtained in step 1-ii is stably dispersed in an aqueous medium due to hydration by a carboxylate of a polyester resin existing in the vicinity of the fine particles (A). . In step 1-iii, the particles are precipitated or destabilized by adding an electrolyte that destroys or reduces the hydration state of the aqueous medium in which the fine particles are dispersed. Examples of the electrolyte used here include acidic substances such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, and oxalic acid. Also, sodium sulfate, ammonium sulfate, potassium sulfate, sodium hydrogen sulfate, ammonium hydrogen sulfate, magnesium sulfate, sodium phosphate, sodium dihydrogen phosphate, sodium chloride, potassium chloride, ammonium chloride, calcium chloride, sodium hydrogen carbonate, ammonium hydrogen carbonate Organic and inorganic water-soluble salts such as sodium acetate can also be effectively used as the electrolyte. These electrolytes may be used alone or as a mixture of two or more kinds of substances. Among them, monovalent cation sulfates and carbonates such as sodium sulfate and ammonium sulfate are preferable in promoting uniform coalescence. The resulting unity is swollen by a solvent, and the hydration state of the particles is unstable due to the addition of an electrolyte. Therefore, the particles are brought together by stirring with low shear (low shearing force). It is preferable that the coalescence proceeds by colliding. It is not preferable to perform the coalescing step under high shear conditions because the particles that have undergone coalescence are split and coalesced simultaneously. It is preferable to control the coalescence process under low shear conditions where only coalescence proceeds without splitting.

  By the way, only by adding an electrolyte or the like, the unitary dispersion in the system becomes unstable, so the unity becomes nonuniform and coarse particles and aggregates may be generated. In order to prevent the formation of an aggregate having a particle size larger than the target particle size by repeating non-uniform coalescence generated by the addition of the electrolyte in this way, before adding the electrolyte, hydroxyapatite It is necessary to add an inorganic dispersion stabilizer such as ionic or nonionic surfactant as a dispersion stabilizer. The dispersion stabilizer used in the step 1-iii needs to have a property capable of maintaining dispersion stability even in the presence of an electrolyte added later. Examples of the dispersion stabilizer having such characteristics include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester. Nonionic emulsifiers such as polyoxyethylene sorbitan fatty acid esters, various pluronics, etc., alkyl sulfate ester type, alkyl sulfonate type anionic emulsifiers, and quaternary ammonium salt type cationic dispersions There are stabilizers. Among these, an anion type and nonionic type dispersion stabilizer is preferable even if it is added in a small amount because it has an effect on the dispersion stability of the system. The cloud point of the nonionic surfactant is preferably 40 ° C. or higher. The above-described surfactants may be used alone or in combination of two or more. Further, in the production method of the present invention, it is possible to prevent non-uniform coalescence by adding an electrolyte in the presence of a dispersion stabilizer (emulsifier). As a result, a sharp particle size distribution is obtained and an improvement in yield is achieved.

  In order to promote uniform coalescence, agitation conditions at the same time are important, and for example, anchor blades, turbine blades, fowler blades, full zone blades, max blend blades, and meniscus blades are used. Among them, it is preferable to use a large wing excellent in uniform mixing properties such as a Max blend wing or a full zone wing. The peripheral speed of the stirring blade for generating a uniform unity is preferably 0.2 to 10 m / s, and more preferably stirring with a low shear of less than 0.2 to 8 m / s. In particular, 0.2 to 6 m / s is preferable. If the peripheral speed of the stirring blade is faster than 10 m / s, fine particles remain, which is not preferable. On the other hand, if the peripheral speed is slower than 0.2 m / s, stirring is not uniform and coarse particles tend to be generated, which is not preferable. Under the above-described conditions, coalescence proceeds only by collision of fine particles, and the coalescence does not dissociate and disperse again. In particular, in the coalescence method, coalescence proceeds preferentially from fine particles, so that generation of ultrafine particles is small and a sharp particle size distribution is achieved, so that an improvement in yield can be achieved.

  When forming a unity, it is preferable to adjust the amount of methyl ethyl ketone which is an organic solvent in the system. Therefore, it is preferable to further dilute the suspension or aqueous solution in the system with water as necessary. Thereafter, a dispersion stabilizer and an electrolyte are sequentially added to perform coalescence. 12-45 mass% is preferable and, as for the amount of the solvent contained in the system before adding electrolyte, it is more preferable that it is 15-30 mass%. If the amount of solvent is less than 12% by mass, the electrolytic mass required for coalescence increases, which is not preferable. On the other hand, if the amount of the solvent is more than 45% by mass, the generation of aggregates due to non-uniform coalescence increases, and the amount of dispersion stabilizer added increases, which is not preferable.

  Further, the amount of the dispersion stabilizer to be used is preferably 0.1 to 3.0% by mass, more preferably 0.3 to 2.0% by mass, for example, based on the solid content. It is especially preferable that it is -1.5 mass%. This is because if it is less than 0.1% by mass, the desired effect of preventing the generation of coarse particles cannot be obtained. On the other hand, when the amount is more than 3.0% by mass, coalescence does not proceed sufficiently even if the amount of the electrolyte is increased, and particles having a predetermined particle diameter cannot be obtained. As a result, fine particles remain and yield. This is because of lowering.

  Moreover, 0.5-15 mass% is preferable with respect to solid content, and, as for the quantity of the electrolyte to be used, it is more preferable that it is 1-12 mass%, and it is especially preferable that it is 1-10 mass%. This is because coalescence does not proceed sufficiently when the amount of electrolyte is less than 0.5% by mass. Further, when the amount of the electrolyte is more than 15% by mass, the coalescence becomes non-uniform, and aggregates and coarse particles are generated to reduce the yield.

  Moreover, 10-50 degreeC is preferable, as for the temporary temperature, it is more preferable that it is 20-40 degreeC, and it is especially preferable that it is 20-35 degreeC. This is because coalescence is difficult to proceed when the temperature is lower than 10 ° C. Moreover, when temperature is higher than 50 degreeC, it is because a coalescence rate will become quick and it will become easy to generate | occur | produce an aggregate and a coarse particle. In the production method of the present invention, it is possible to produce a unity by uniting under a low temperature condition of 20 to 40 ° C., for example.

  By the way, in order to maintain the frictional charging performance satisfactorily, it is effective to prevent the colorant and the like from being exposed on the surface of the toner particles, that is, to have a toner structure in which the colorant and the like are included in the toner particles. The deterioration of the chargeability accompanying the reduction in the toner particle size is caused by the fact that a part of the contained colorant and other additives (usually a release agent) is exposed on the toner particle surface. That is, even if the content (% by mass) of the colorant is the same, the surface area of the toner particle is increased by reducing the particle size, and the ratio of the colorant and the release agent exposed on the surface of the toner particle is increased. As a result, the composition of the toner particle surface changes greatly, and the frictional charging performance of the toner particles changes greatly, making it difficult to obtain an appropriate chargeability.

  The toner particles produced by the above production method are characterized in that a colorant, a release agent and the like are encapsulated in a polyester resin. Whether the colorant, the release agent or the like is not exposed on the toner particle surface can be easily determined by observing the cross section of the particle with a TEM (transmission electron microscope), for example. More specifically, a cross-section obtained by embedding the toner particles with a resin and cutting with a microtome is dyed with ruthenium oxide or the like if necessary, and observed with a TEM, so that a colorant or a release agent is included in the particles. It can be confirmed that the particles are dispersed almost uniformly.

  The unitary shape obtained in step 1-iii can be changed from an indeterminate shape to a spherical shape depending on the degree of unity. For example, it can be changed from 0.94 to 0.99 in terms of average circularity. The average circularity can be obtained by taking a SEM (scanning electron microscope) photograph of the finally obtained toner particles and calculating with an image analysis device (manufactured by Luzex AP Co., Ltd.). Since it can be easily obtained by using a flow type particle image analyzer FPIP-1000 manufactured by Sysmex Corporation, a value measured by this apparatus is used as an average circularity in this specification.

  The shape of the toner particles has at least one spherical surface and is preferably composed of a plurality of spherical surfaces, and the average circularity is preferably 0.95 or higher. More preferably, it is 96 or more. In particular, it is most preferable that it is 0.97 or more. This is because the powder fluidity and the transfer efficiency are improved by setting the average circularity to a substantially spherical or spherical shape having an average circularity of 0.97 or more. . In particular, as the particle size decreases, the difference in terms of powder flowability, transfer efficiency, and toner consumption increases between spherical and irregular shapes.

  Next, the organic solvent is removed from the aqueous medium including the unity obtained in the uniting step (step 1-iv). The unity obtained in the uniting step contains an organic solvent and swells, so that it tends to aggregate under high temperature conditions. Therefore, it is preferable to carry out the desolvation under reduced pressure in order to carry out the desolvation quickly under a low temperature condition.

  Next, the combined body (B) is separated from the aqueous medium, washed and dehydrated (step 1-v). Separation from the aqueous medium can be performed by a known and commonly used means such as a centrifugal separator, a filter press, a belt filter or the like. Subsequently, the toner particles can be obtained by drying the particles. Here, in the case where a dispersion stabilizer is used in Step 1-iii, it is preferable to wash more sufficiently.

    The unitary body (B) (water-containing colorant-containing resin particles) obtained by the above step is subjected to the following second step.

  The toner particle size distribution is preferably 50% volume particle size / 50% number particle size of 1.25 or less, as measured with a multisizer TAII type (aperture tube diameter: 100 μm) manufactured by Coulter, Inc. The following is more preferable. This is because it is easy to obtain a good image when it is 1.25 or less. The GSD (geometric standard deviation) is preferably 1.30 or less, and more preferably 1.25 or less. The GSD is a value obtained from the square root of (16% volume particle size / 84% volume particle size) as measured by a multisizer TAII type manufactured by Coulter. The smaller the GSD value, the sharper the particle size distribution and the better the image. Moreover, it is preferable to have such a sharp particle size distribution because the water content after the first step can be reduced and the fluidity in the second step is improved.

  The volume average particle diameter of the toner is preferably in the range of 1 to 13 μm from the viewpoint of the obtained image quality, etc., and about 3 to 10 μm is more preferable because it can be easily matched with the current machine. For a color toner, a range in which the volume average particle diameter is 3 to 8 μm is preferable. When the volume average particle size is reduced, not only the resolution and gradation are improved, but also the thickness of the toner layer forming the printed image is reduced and the toner consumption per page is reduced. It is.

The polyester resin used in the present invention is preferably a mixture of a cross-linked polyester resin and a linear polyester resin, and can be obtained by reacting a compound selected from the following raw materials.
The cross-linked polyester is preferably produced by reacting a divalent polybasic acid or a derivative thereof, a divalent alcohol, and a polyvalent compound as a cross-linking agent. In particular, it is preferable to produce by reacting a divalent polybasic acid or a derivative thereof, a divalent aliphatic polyhydric alcohol, and a polyvalent epoxy compound as a crosslinking agent.
The linear polyester resin is produced by reacting a divalent polybasic acid with a divalent alcohol. In particular, it is preferable to produce by reacting a divalent polybasic acid with a divalent aliphatic alcohol.

  The following divalent basic acids can be used as the acid component used when producing the cross-linked polyester resin and the linear polyester resin. For example, divalent basic acid compounds include phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, adipic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid, hexahydrophthalic anhydride, tetrahydroanhydride Examples thereof include dicarboxylic acids such as phthalic acid, cyclohexanedicarboxylic acid, succinic acid, malonic acid, glutaric acid, azelaic acid, sebacic acid, and derivatives or esterified products thereof.

  In addition, as the divalent aliphatic alcohol component, the following alcohols can be used. Examples of the divalent aliphatic alcohol include 1,4-cyclohexanedimethanol, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, neopentyl glycol, butanediol, pentanediol, and hexanediol. Diols such as polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide random copolymer diol, ethylene oxide-propylene oxide block copolymer diol, ethylene oxide-tetrahydrofuran copolymer diol, polycaprocactone diol It is done.

Use of an aliphatic alcohol in the cross-linked polyester resin and the linear polyester resin is preferable because compatibility with waxes is improved and offset resistance is improved. Moreover, fixing property at low temperature is improved by softening the polyester main chain.
When producing a crosslinked polyester resin, a polyvalent epoxy compound is further used as a crosslinking agent. Examples of such compounds include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, ethylene glycol diglycidyl ether, hydroquinone diglycidyl ether, N, N-diglycidyl aniline, glycerin triglycidyl ether. , Trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetrakis 1,1,2,2 (p-hydroxyphenyl) ethane tetraglycidyl ether, cresol novolac type epoxy resin, phenol novolac type epoxy Resin, polymer or copolymer of an epoxy group-containing vinyl compound, epoxidized resorcinol-acetone condensate, partial energy Carboxymethyl polybutadiene, polymers of vinyl compounds having an epoxy group, or a copolymer, such as semi-drying or drying fatty acid ester epoxy compound. Among the above compounds, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, trimethylol ethane Triglycidyl ether and pentaerythritol tetraglycidyl ether are more preferably used.

  Specifically, as an example of bisphenol A type epoxy resin, Dainippon Ink & Chemicals, Inc. Epicron 850, Epicron 1050, Epicron 2055, Epicron 3050, etc. are examples of bisphenol F type epoxy resin. Epicron 830, Epicron 520, etc. manufactured by Dainippon Ink & Chemicals, Inc. as examples of orthocresol novolak type epoxy resins are N-660, N-665, N-667, N-670, N-673. N-680, N-690, N-695 and the like, and examples of the phenol novolac type epoxy resin include Epicron N-740, N-770, N-775, N-865, etc. manufactured by Dainippon Ink and Chemicals, Inc. Can be mentioned. Examples of the polymer or copolymer of a vinyl compound having an epoxy group include a homopolymer of glycidyl (meth) acrylate, an acrylic copolymer, and a copolymer with styrene.

  Moreover, the epoxy compound mentioned above can also be used in combination of 2 or more types, Furthermore, the mono epoxy compound described below can also be used together as a modifier | denaturant of resin. Examples of the monoepoxy compound that can be used at the same time include phenyl glycidyl ether, alkylphenyl glycidyl ether, alkyl glycidyl ether, alkyl glycidyl ester, glycidyl ether of alkylphenol alkylene oxide adduct, α-olefin oxide, monoepoxy fatty acid alkyl ester, etc. Is mentioned.

  By using these monoepoxy compounds in combination, fixability and resistance to offset at high temperatures are improved. Among these, alkyl glycidyl esters are particularly preferably used. Specific examples include neodecanoic acid glycidyl ester (Cardura E; manufactured by Shell Japan).

  The cross-linked polyester resin and the linear polyester resin can be obtained, for example, by performing a dehydration condensation reaction or a transesterification reaction in the presence of a catalyst using the raw material components described above. The reaction temperature and reaction time at this time are not particularly limited, but are usually 150 to 300 ° C. and 2 to 24 hours.

  As the catalyst for performing the above reaction, for example, tetrabutyl titanate, zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, paratoluenesulfonic acid, and the like can be used as appropriate.

  The use ratio of the crosslinked polyester resin and the linear polyester resin used in the present invention is preferably (mass of crosslinked polyester resin) / (mass of linear polyester resin) = 5 / 95-60 / 40, It is more preferably 10/90 to 40/60, and particularly preferably 20/80 to 40/60. When the ratio of the cross-linked polyester resin is less than 5% by mass, the hot offset resistance is lowered, which is not preferable. In addition, the coalescence speed is lowered, and the dispersibility of wax, colorant and the like is lowered, which is not preferable. On the other hand, if it is more than 60% by mass, the melt viscosity (T1 / 2 temperature) increases and the low-temperature fixability decreases, which is not preferable.

The glass transition temperature (Tg) of the cross-linked polyester resin is preferably 60 to 85 ° C, and particularly preferably 60 to 75 ° C. When the glass transition temperature (Tg) is lower than 55 ° C., a blocking phenomenon (thermal aggregation) tends to occur when the toner is stored, transported, or exposed to a high temperature inside the developing device of the machine. Further, if the glass transition temperature (Tg) is higher than 85 ° C., the low-temperature fixability is lowered, which is not preferable.
The glass transition temperature (Tg) of the linear polyester resin is preferably 40 to 70 ° C, and particularly preferably 50 to 65 ° C. When the glass transition temperature (Tg) is lower than 40 ° C., a blocking phenomenon (thermal aggregation) tends to occur when the toner is stored, transported, or exposed to a high temperature inside the developing device of the machine. On the other hand, if the glass transition temperature (Tg) is higher than 70 ° C., the low-temperature fixability is lowered, which is not preferable.

Further, the softening point of the cross-linked polyester resin is preferably 160 ° C. or higher, and more preferably 160 ° C. to 220 ° C. Here, the softening point of the cross-linked polyester resin is more preferably 170 ° C to 200 ° C, and particularly preferably 170 ° C to 190 ° C. This is because when the softening point is less than 160 ° C., the toner tends to cause agglomeration phenomenon, which is likely to cause trouble during storage or printing, and when it exceeds 220 ° C., the fixability tends to deteriorate. is there.
Moreover, as a softening point of a linear polyester resin, it is preferable that it is 90 degreeC or more, and it is preferable that it is 90 to 130 degreeC especially. Here, the softening point of the linear polyester resin is more preferably 90 ° C to 120 ° C, and particularly preferably 90 ° C to 110 ° C. As with the cross-linked polyester resin, when the softening point is less than 90 ° C., the glass transition temperature is lowered, and the toner tends to cause aggregation phenomenon, which is likely to cause trouble during storage or printing. If the temperature exceeds 130 ° C., the fixability tends to deteriorate.

  The softening point of the mixture of the cross-linked polyester resin and the linear polyester resin is preferably 100 ° C to 150 ° C. Here, the softening point of the mixture is more preferably 110 ° C to 150 ° C, and particularly preferably 120 ° C to 140 ° C. As described above, when the softening point is less than 100 ° C., the toner tends to agglomerate, which is likely to cause trouble during storage and printing. When the softening point exceeds 150 ° C., the fixing property is deteriorated. It is because it becomes easy to do.

The softening point of the polyester resin is defined by a T1 / 2 temperature measured using a flow tester CFT-500 manufactured by Shimadzu Corporation, which is a constant load extrusion type capillary rheometer. The measurement conditions with the flow tester were: piston cross-sectional area 1 cm ² , cylinder pressure 0.98 MPa, die length 1 mm, die hole diameter 1 mm, measurement start temperature 50 ° C., temperature increase rate 6 ° C./min, sample mass 1.5 g. Performed under conditions.

  In the production method of the present invention, a release agent can be used. In this case, the release agent may be selected from hydrocarbon waxes such as polypropylene wax, polyethylene wax, and Fischer-Tropsch wax, and natural ester waxes such as synthetic ester wax, carnauba wax, and rice wax. A mold is used. Of these, natural ester waxes such as carnauba wax and rice wax, synthetic ester waxes obtained from polyhydric alcohols and long-chain monocarboxylic acids, and hydrocarbon waxes such as Fischer-Tropsch wax are preferably used. As the synthetic ester wax, for example, WEP-5 (manufactured by NOF Corporation) is preferably used. If the content of the release agent is less than 1% by mass, the releasability is likely to be insufficient, and if it exceeds 40% by mass, the wax is likely to be exposed on the toner particle surface, and the chargeability and storage stability are reduced. Since it becomes easy, the inside of the range of 1-40 mass% is preferable.

  In addition, a charge control agent can be used. The positively chargeable charge control agent is not particularly limited, and known and commonly used nigrosine compounds, quaternary ammonium compounds, onium compounds, triphenylmethane compounds, and the like can be used for toner. A basic group-containing compound such as an amino group, an imino group, or an N-heterocycle, such as a tertiary amino group-containing styrene acrylic resin, can also be used in combination with the nigrosine dye as a positively chargeable charge control agent. Depending on the application, a small amount of a negative charge control agent such as an azo dye metal complex or a salicylic acid derivative metal complex salt may be used in combination. Negative charge control agents include trimethylethane dyes, metal complexes of salicylic acid, metal complexes of benzylic acid, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes Examples thereof include dyes, calixarene-type phenol condensates, cyclic polysaccharides, resins containing carboxyl groups and / or sulfonyl groups.

  The content of the charge control agent is preferably 0.01 to 10% by mass. It is especially preferable that it is 0.1-6 mass%.

  There is no restriction | limiting in particular about a coloring agent, A well-known and usual thing is used. Examples of black colorants include carbon black, C.I. I. Pigment Black 11 and other iron oxide pigments, C.I. I. And iron-titanium complex oxide pigments such as Pigment Black 12. Examples of carbon black include furnace black, channel black, acetylene black, thermal black, and lamp black.

  As the blue colorant, phthalocyanine C.I. I. Pigment Blue 1, 2, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 15, 16, 17: 1, 27, 28, 29, 56, 60, 63, and the like. The blue colorant is preferably C.I. I. Pigment Blue 15: 3, 15, 16, 60, and most preferably C.I. I. Pigment Blue 15: 3,60.

  Examples of yellow colorants include C.I. I. Pigment Yellow 1, 3, 4, 5, 6, 12, 13, 14, 15, 16, 17, 18, 24, 55, 65, 73, 74, 81, 83, 87, 93, 94, 95, 97, 98, 100, 101, 104, 108, 109, 110, 113, 116, 117, 120, 123, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 156, 168, 169, 170, 171, 172, 173, 180, 185 and the like. Preferably, C.I. I. Pigment Yellow 17, 74, 93, 97, 110, 155 and 180, more preferably C.I. I. Pigment Yellow 74, 93, 97, 180, and C.I. I. Pigment Yellow 93, 97, 180 is preferable.

  Further, examples of red colorants include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 17, 18, 22, 23, 31, 37, 38, 41, 42, 48: 1 48: 2, 48: 3, 48: 4, 49: 1, 49: 2, 50: 1, 52: 1, 52: 2, 53: 1, 54, 57: 1, 58: 4, 60: 1 63: 1, 63: 2, 64: 1, 65, 66, 67, 68, 81, 83, 88, 90, 90: 1, 112, 114, 115, 122, 123, 133, 144, 146, 147, 149,150,151,166,168,170,171,172,174,175,176,177,178,179,185,187,188,189,190,193,194,202,208,209,214, 216, 220, 221, 224, 2 42,243,243: 1,245,246,247 etc. are mentioned. Preferably, C.I. I. Pigment Red 48: 1, 48: 2, 48: 3, 48: 4, 53: 1, 57: 1, 122 and 209, most preferably C.I. I. Pigment Red 57: 1, 122, and 209.

  The content of these colorants is preferably 1 to 20% by mass with respect to the whole toner. Especially, it is more preferable that it is 2-18 mass%, and it is especially preferable that it is 2-15 mass%. These colorants can be used alone or in combination of two or more.

Next, the second step will be described in detail.
First, the water-containing colorant-containing resin particles obtained in the first step are adjusted to a relative humidity of 70 to 100% under mechanical stirring at normal pressure in a dryer equipped with a stirrer that can be decompressed. By removing the hydrophobic organic solvent remaining in the water-containing colorant-containing resin particles by replacing the moisture in the water-containing colorant-containing resin particles with the wet gas (I), the remaining water is subjected to mechanical stirring. Remove under reduced pressure.
The wet cake of the water-containing colorant-containing resin particles is preferably pulverized in advance using a stirrer such as a Henschel mixer. Furthermore, it is preferable to crush by adding an inorganic oxide having a BET surface area of 30 to 200, particularly preferably 50 to 150. This is because by adding an inorganic oxide in advance, the inorganic oxide acts as a spacer agent and can prevent aggregation and fusion during the drying process. The bulk ratio is preferably 0.2 to 0.8 g / ml, more preferably 0.3 to 0.6 g / ml. When the bulk ratio is in the above range, good stirring can be performed, and the removal of the solvent and water proceeds more efficiently. Further, it is preferable because the bag filter is not easily clogged, and as a result, the pressure loss is hardly increased. The inorganic oxide is not particularly limited, but for example, inorganic oxide such as silicon dioxide, titanium oxide, aluminum oxide, and the like, and surface thereof with a hydrophobic treatment agent such as silicone oil or silane coupling agent. Processed ones are raised.
It is possible to prepare a wet cake of water-containing colorant-containing resin particles and an inorganic oxide in the dryer, and perform drying and crushing in parallel under mechanical stirring by the dryer. It is preferable to add and pulverize, since the humidity-controlled gas and particles at normal pressure come into efficient contact with each other, thereby improving the drying efficiency. The obtained crushed material is put into a drier, and a humidity control gas at normal pressure is inserted under mechanical stirring to replace and remove the remaining hydrophobic organic solvent.

  As the dryer used in the production method of the present invention, any dryer with a stirrer can be used as long as it can be dried under reduced pressure. An example of a dryer used in the production method of the present invention is shown in FIG.

  The dryer shown in FIG. 1 includes an inverted conical dryer body 17, a stirring motor 15 disposed on the top of the dryer body 17, and a screw type connected to the stirring motor 15 via a drive arm. A stirrer 12 is provided, and the stirrer 12 rotates along the inner peripheral surface of the dryer main body 17 while rotating. The water-containing colorant-containing resin particles charged into the dryer shown in FIG. 1 are stirred and further dispersed while being lifted upward from below by the stirrer 12. For this reason, the water-containing colorant-containing resin particles in the dryer main body 17 are efficiently stirred and mixed throughout.

  A bag filter 16 is attached to the upper portion of the dryer main body 17 in FIG. 1, and further, a condenser 19, a condensate water receiving tank 20, and a vacuum pump 21 are provided in that order in the bag filter 16 to perform drying under reduced pressure. However, the water or hydrophobic organic solvent volatilized in the water-containing colorant-containing resin particles or from the surface can be condensed and removed. The dryer main body 17 shown in FIG. 1 has a double structure, and is connected by a pipe so that hot water can be supplied from a hot water production apparatus provided in the double structure portion. Thereby, it is possible to appropriately control the temperature in the dryer main body 17 and to dry at a desired temperature.

  Further, a humidity control gas supply port 11 for feeding gas (I) whose relative humidity is adjusted is provided on the lower side surface of the dryer body 17. The gas (I) whose relative humidity is adjusted is converted into a gas sent from a gas (air) generator 1 such as a compressed gas cylinder or a blower and water vapor sent from a steam (steam) generator 4 by a humidity-controlled gas generator 7. Made by mixing. The gas sent from the gas (air) generator 1 is preferably air, but an inert gas such as nitrogen gas can also be used. The gas sent from the gas (air) generator 1 passes through the gas (air) flow meter 2 and the gas (air) thermometer 3 and is sent to the humidity control gas generator 7. Further, the water vapor sent from the steam generator 4 passes through the steam flow meter 5 and the steam thermometer 6 and is sent to the humidity control gas generator 7. Further, the gas (I) conditioned by the humidity control gas generator 7 to adjust the relative humidity passes through the humidity control gas flow meter 8, the humidity control gas thermometer 9, and the humidity control gas hygrometer 10 in order. It is sent to the gas supply port 11.

The water content of the wet cake of the water-containing colorant-containing resin particles is preferably in the range of 10 to 40% after the first step. Further, it is preferably in the range of 20 to 35%, and particularly preferably in the range of 25 to 30%. When the moisture content of the wet cake is within the above range, the removal of the residual organic solvent by the humidity control gas effectively acts on the wet wet cake under normal pressure conditions. Removal of the organic solvent proceeds efficiently. Further, it is preferable because the time for removing moisture by drying under reduced pressure can be shortened.
The relative humidity of the gas (I) is preferably 70 to 100%, particularly preferably 80 to 100%. When the relative humidity is within this range, the water in the water-containing colorant-containing resin particles is difficult to remove first, and the replacement of the water with the hydrophobic organic solvent can be sufficiently performed. Moreover, it is preferable that the inlet temperature of gas (I) is 30-60 degrees C or less. Furthermore, the range of 35-50 degreeC is preferable, and the range of 35-45 degreeC is the most preferable especially. When the inlet temperature of the gas (I) is within this range, particles swollen with the solvent are less likely to aggregate and fuse with the liquid film. Further, the replacement with the hydrophobic organic solvent is quick, and the time required for replacing the solvent can be shortened. In addition, the surface temperature of the humidity control gas supply port 11 that is in contact with the gas (I) whose relative humidity has been adjusted should be adjusted within a range of ± 2 ° C. from the temperature of the humidity control gas to be inserted. preferable. It is preferable that the surface temperature of the humidity control gas supply port 11 be within a range of ± 2 ° C. because condensation hardly occurs on the inner surface of the dryer and toner aggregates due to the condensed moisture hardly occur. Further, the relative humidity of the gas (I) is difficult to decrease, and the solvent removal effect by the gas (I) is easily maintained.
When the moisture content of the wet cake after the first step is high, it is preferable to adjust the moisture content of the cake by feeding a humidity control gas (gas (II)) having a relative humidity of 60% or less. Furthermore, it is preferable to feed humidity control gas of 40% or less. The air volume of the gas (I) is a water-containing colorant-containing resin particle having a bulk ratio of 0.2 to 0.8 g / ml and an average particle diameter of 1 to 13 μm. For example, in the “Nauter Mixer NXV-1” manufactured by Hosokawa Micron The range of 5 to 150 L / min · Kg per unit weight of the water-containing colorant-containing resin particles is preferable, and the range of 10 to 80 L / min / Kg is more preferable. When the air volume is within this range, contact is made uniformly and the removal efficiency of the hydrophobic organic solvent is good, which is preferable. Also, channeling is less likely to occur in the hook, and the pressure loss of the bug is less likely to increase. It is preferable to set an optimum value as appropriate depending on the volume of the dryer.
In the production method of the present invention, it is important to feed the gas (I) at normal pressure and at the same time mechanically stir with a stirrer. Normally, when a high-humidity conditioning gas is fed into a wet cake in a wet state, a liquid film adheres to the particle surface and aggregation between particles occurs. However, by mechanically stirring using a stirrer as shown in FIG. 1, compression and cutting force are applied to individual particles, and the agglomeration is crushed. It is thought to be prevented. For example, in the “Nauter mixer NXV-1” manufactured by Hosokawa Micron, the revolution speed is preferably in the range of 0.9 to 3.6 rpm. On the other hand, the rotation speed is preferably in the range of 30 to 120 rpm.
Moreover, compared with a fluidized bed, since a fluidized bed is not formed, the expansion of the layer is not large, and the amount of charge can be increased, so that productivity is excellent. On the other hand, although the reason is not clear, the removal effect by the replacement of the same hydrophobic organic solvent is high although it is estimated that the contact efficiency with the humidity control gas is inferior to that of the fluidized bed. This is presumably because of good mixing by mechanical stirring. In addition, the volume of air per unit area and unit time (superficial velocity) is much smaller than in a fluidized bed.
In addition, the product temperature control is important for efficient drying, but the amount of heat from the heat transfer surface of the dryer inner surface by the jacket (the dryer main body 17 is a double structure part) and the heat of the humidity control gas is heated. Since the heat exchange between the amount of heat supplied and the particles is performed under normal pressure in the present production method, the heat exchange efficiency is higher than in a vacuum state under reduced pressure, and there is an advantage that stable temperature control is possible. Although there is no restriction | limiting in particular in processing time, For example, 1 to 20 hours are preferable.

Subsequently, the remaining water is removed while continuing stirring under reduced pressure, whereby a dry powder of the colorant-containing resin particles can be obtained. In the wet cake of the water-containing colorant-containing resin particles, the hydrophobic organic solvent and water remaining in the particles are present, and water is also present between the particles. The water between the particles can be easily removed by feeding dry gas through the fluidized bed, but the water remaining in the particles is preferably removed efficiently by raising the drying temperature. In order to efficiently remove moisture in the particles at a low temperature, it is necessary to vacuum dry under reduced pressure. By drying in vacuum, moisture inside the particles can be efficiently removed. Moreover, the moisture content of the wet cake after completion | finish of inflow of gas (I) has the preferable range of 10-35%. Furthermore, the range of 15 to 30% is preferable. The range of 15 to 25% is most preferable. When the moisture content of the wet cake after completion of the gas (I) feed is within this range, the removal efficiency of the hydrophobic organic solvent is good. In addition, moisture removal by vacuum drying under reduced pressure tends to proceed quickly. When the moisture content of the wet cake after the completion of the gas (I) transfer is high, a humidity control gas with a relative humidity of 60% or less should be supplied for the purpose of removing moisture adsorbed between the particles. It is preferable to reduce the moisture content of the cake. Furthermore, it is preferable to feed humidity control gas of 40% or less.
About temperature conditions at the time of vacuum-drying under reduced pressure, the product temperature is preferably within a range of 35 to 45 ° C. If it is this range, it will be easy to remove water efficiently. Moreover, there is little possibility that fusion will occur, which is preferable. It is preferable to adjust the temperature of the jacket appropriately so that the product temperature falls within an appropriate range. Although there is no restriction | limiting in particular in processing time, For example, 1 to 20 hours are preferable until a moisture content will be 0.2% or less.

  The dried toner particles can be used as a developer as they are, but it is preferable to add known external additives such as inorganic oxide fine particles and organic polymer fine particles to the toner particle surfaces as external additives for toner. . Hydrophobic silica, inorganic fine particles such as titanium oxide, or organic fine particles are externally added to toner particles to improve physical properties such as fluidity and chargeability when used as a dry developer by electrostatic printing. effective. As the type of external additive, various silicone oils, hydrophobic silica treated with a silane coupling agent, or the like is preferably used. Examples thereof include hydrophobic silica treated with dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, fluorine-modified silicone oil, and olefin-modified silicone oil. The external addition method is processed using a known and commonly used model.

  A two-component electrostatic image developer can be obtained by mixing a carrier with the toner particles. The electrostatic charge image developer comprises a toner produced by the production method of the present invention and a magnetic carrier, preferably a magnetic carrier whose surface is coated with a resin.

  Iron powder, magnetite, ferrite, etc. used in the usual two-component development system can be used as the carrier core agent (magnetic carrier) used in the electrostatic image developer, but the true specific gravity is low, the resistance is high, and the environment Ferrite or magnetite that is excellent in stability and easy to be spherical and has good fluidity is preferably used. The shape of the core agent can be used without any problem, for example, spherical or irregular. The average particle size is generally 10 to 200 μm, but 30 to 110 μm is preferable for printing a high resolution image.

  Examples of the coating resin for coating these core agents include polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether polyvinyl ketone, vinyl chloride / vinyl acetate. Copolymers, styrene / acrylic copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, (meth) acrylic resins, polyesters, polyurethanes, polycarbonates, phenol resins, amino resins, melamine resins, benzoguanamine resins Urea resin, amide resin, epoxy resin and the like can be used.

  Among these, silicon resin and (meth) acrylic resin are particularly excellent in charging stability and coating strength, and can be used more suitably. In addition, the charging characteristics of a developer composed of toner particles and a carrier can be adjusted by adjusting the coating amount of a coating agent such as silicon, adding a charge control agent, or adding a conductive material typified by carbon. That is, the resin-coated carrier used in the present invention is a resin-coated magnetic carrier coated with one or more resins selected from silicon resin and (meth) acrylic resin using ferrite or magnetite as a core agent. It is preferable to adjust the charging characteristics by adding a charge control agent, carbon or the like to the coating agent.

  In addition, since the toner produced by the production method of the present invention has a small amount of solvent and does not have coarse particles due to fusion during drying, it is possible to use a normal non-magnetic one-component developing type printing apparatus or two-component developing type. A high-quality image can be obtained by using it in a printing apparatus, a magnetic one-component developing type printing apparatus, or the like. Further, on a flexible printed circuit board having an electrode having a function of adjusting a toner passing amount of powder toner that is frictionally charged using a nonmagnetic one-component developing device having a developer carrying roll and a layer regulating member. Therefore, it can be suitably used for a so-called toner jet type printer in which an image is formed by spraying directly on the paper on the back electrode through the hole. The toner produced by the production method of the present invention forms an electrostatic image on the latent image carrier, and develops the obtained electrostatic image using a developer carried on the developer carrier, Printing can be performed by an image forming method in which the toner image formed on the cargo image carrier is transferred onto a transfer material such as paper or film, and the toner image on the transfer material is thermally fixed by a heat roll.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In Examples and Comparative Examples, unless otherwise indicated, “part” means “mass part” and “water” means deionized water. A synthesis example of the binder resin used for preparing the toner first is shown below.

<Synthesis example of cross-linked polyester resin>
(Synthesis example of resin 1)
Terephthalic acid 252 parts by mass Isophthalic acid 63 parts by mass Propylene glycol 122 parts by mass Neopentyl glycol 21 parts by mass Ethylene glycol 12 parts by mass Tetrabutyl titanate 2.5 parts by mass Epicron 830 9.4 parts by mass Cardura E 9.0 parts by mass

  The above raw materials were put into a 2 L glass four-necked flask and a thermometer, a stirring rod and a nitrogen introducing tube were attached, and the reaction was carried out in an electric heating mantle heater at 240 ° C. for 10 hours under a normal pressure nitrogen stream. Thereafter, the pressure was reduced successively and the reaction was continued at 10 mmHg. The reaction was followed by a softening point according to ASTM E28-517, and the reaction was terminated when the softening point reached 160 ° C.

The obtained polymer was a colorless solid, and had an acid value of 10.5, a glass transition temperature of 74 ° C. by a DSC measurement method, and a softening point (T1 / 2) by a flow tester of 180 ° C.
* Epicron 830: Bisphenol F type epoxy resin manufactured by Dainippon Ink & Chemicals, Inc.
Epoxy equivalent 170 (g / eq)
* Cardura E (Shell Japan alkyl glycidyl ester)
Epoxy equivalent 250 (g / eq)
<Synthesis example of linear polyester resin>

(Synthesis example of resin 2)
Terephthalic acid 315 parts by weight Neopentyl glycol 21 parts by weight Ethylene glycol 12 parts by weight Propylene glycol 122 parts by weight Tetrabutyl titanate 2.5 parts by weight or more of raw materials are placed in a 2 L glass four-necked flask, thermometer, stirring rod and nitrogen An introduction pipe was attached, and the reaction was continued for 12 hours at 240 ° C. in an electric heating mantle heater under a normal pressure nitrogen stream, and then the pressure was reduced successively and the reaction was continued at 10 mmHg. The reaction was followed by a softening point according to ASTM E28-517, and the reaction was terminated when the softening point reached 100 ° C.

  The obtained polymer was a colorless solid having an acid value of 11.0, a glass transition temperature of 57 ° C. by DSC measurement method, and a softening point (T1 / 2) by a flow tester of 103 ° C.

(Example of preparation of release agent master dispersion)
Carnauba wax "Carnauba wax No. 1" (imported by Yoko Kato) 30 parts, linear polyester resin (resin synthesis example 2) 70 parts and methyl ethyl ketone 150 parts were premixed with Desper and then Starmill LMZ-10 (Ashizawa Fine) (Made by Tec Co., Ltd.) to obtain a release agent fine dispersion W-1 having a solid content of 40% by mass.

(Example of preparation of colorant master solution)
50 parts by mass of a cyan pigment (Cyan Pigment “Ket-111” manufactured by Dainippon Ink & Chemicals, Inc.) and 50 parts by mass of a linear polyester resin (Synthesis Example 2) are combined with 100 parts by mass of an organic solvent (methyl ethyl ketone). ) And pre-dispersing with a desper, followed by wet dispersion with Starmill LMZ-10 (manufactured by Ashizawa Finetech) to prepare a master solution of each colorant. The solid content of the finally obtained master solution was 45%. Further, the obtained master solution was diluted with the resin and MEK of Synthesis Example 2 and observed with a 400 × optical microscope for the finely dispersed state of the colorant and the presence or absence of coarse particles. Was.

(Example of mill base preparation)
The release agent dispersion, the colorant master solution, or the colorant master chip, the dilution resin (additional resin), and methyl ethyl ketone have a solid content of 65% and a temperature condition of 30 to 40 ° C. K. The mixture was mixed at 3600 rpm with a homodisper blade (TK Robotics: Tokushu Kika Kogyo Co., Ltd.) for 3 hours, and dissolved and dispersed. The resulting mixture was readjusted to a solid content of 65% to make a mill base. Table 1 shows the formulation of the produced mill base.

(Preparation example of toner base particles)
A cylindrical 2 L separable flask having a desper blade as a stirring blade is charged with 461.5 parts (300 parts solids) of mill base MB-1, and then 50 parts of 1N ammonia water is added. K. After sufficiently stirring at 3600 rpm with a homodisper blade (TK Robotics: Tokushu Kika Kogyo Co., Ltd.), the temperature was adjusted to 23 ° C. Subsequently, the stirring speed was changed to 7000 rpm and 340 parts of deionized water was added dropwise at 10 g / min to prepare an emulsified dispersion. The peripheral speed of the stirring blade at this time was 14.7 m / s. Further, when the slurry was observed with an optical microscope, it was observed that the resin was dissolved and the pigment and release agent fine particles were dispersed.

Next, the stirring speed was changed to 3600 rpm, and 2.2 parts of an anionic emulsifier Neogen SC-F (Daiichi Kogyo Seiyaku Co., Ltd.) was diluted to 32.5 parts of water and added. Thereafter, the stirring blade was changed to a Max blend blade, the temperature was adjusted to 25 ° C., the rotation speed was adjusted to 400 rpm, and 120 parts of a 3.5% ammonium sulfate aqueous solution (first stage electrolyte) was added at 10 g / min. After that, the number of revolutions was adjusted to 158 rpm, and stirring was continued until the particle size reached 4 μm. Subsequently, 50 parts of ammonium sulfate aqueous solution (second-stage electrolyte) in which the rotation speed was adjusted to 400 rpm and the ammonium sulfate concentration was changed to 4.5% was dropped at 10 g / min, and the stirring was changed to 158 rpm. When the particle size grew to 7.8 μm, dilution water was added to complete the coalescence operation. The peripheral speed of the stirring blade at this time was 0.34 m / s. Moreover, the addition amount with respect to solid content of electrolyte was 2.2%. Thereafter, methyl ethyl ketone was distilled off under reduced pressure until the degree of vacuum was 4 kPa. The slurry after removing the solvent was subjected to solid-liquid separation and washing repeatedly, and then a utcake of colorant resin particles was obtained. The moisture content of the wet cake was 33%, the solvent contained in the wet cake was 1750 PPM, the volume average particle size was 7.7 μm, the volume average particle size / number average particle size = 1.11, and the average circularity was 0.974. Met.
The above properties were measured using the following evaluation apparatus.

1) Measurement of particle size and particle size distribution A sample is prepared by suspending the mother toner after drying in water containing a surfactant. Next, the particle size and particle size distribution of the mother toner were measured by Coulter Counter Multisizer TAII using a 100 μm aperture tube.

2) Measurement of average circularity The average circularity can be obtained by taking a SEM (scanning electron microscope) photograph of the toner particles, and measuring and calculating it. In the present invention, however, Toa Medical Electronics It calculates | requires by the Co., Ltd. flow type particle image analyzer FPIP-1000. The flow-type particle image analyzer FPIP-1000 is an apparatus that captures the size and shape of fine particles such as toner particles, and particle imaging is performed as follows.

  First, a sample is prepared by suspending a small amount of the dried mother toner in water containing a surfactant. Next, this sample is allowed to flow down into a transparent and flat cell provided in the flow type particle image analyzer FPIP-1000. A light source that emits pulsed light is installed on one side of the cell, and an imaging camera is provided on the opposite side of the cell so as to face the light source. The toner particles in the sample flowing down in the cell of the FPIP-1000 are captured as a still image by a camera facing the light source while holding the cell when irradiated with pulsed light.

  Based on the image of the toner particle thus captured, the contour of each toner particle is extracted by the image analysis device, and the projected area and peripheral length of the toner particle image (peripheral length of the toner particle projected image) are calculated. The Further, from the calculated projected area of the toner particle image, the circumference of a circle having the same area (the circumference of the circle having the same area as the toner particle projected area) is calculated. The average circularity is obtained by dividing the circumference of the circle having the same area as the toner particle projection area calculated in this way by the circumference of the toner particle projection image.

The conditions when measuring with the above apparatus are as follows.
(1) Preparation of toner particle suspension 0.1 g of a surfactant (ELCLEAR (manufactured by Chugai Photo Chemical Co., Ltd.)) is added to 20 g of water, and 0.04 g of a mother toner as a sample is further added. The toner particles are suspended in water using an ultrasonic disperser.
(2) Measurement conditions Measurement temperature: 25 ° C
Measuring humidity: 60%
Number of toner particles to be measured: 5000 ± 2000 (3) Residual solvent amount About 250 mg of a sample is precisely weighed into a glass screw bottle, and THF is added to make the total amount about 4460 mg (corresponding to 5 μL). After standing for 1 hour, shake well to dissolve the sample. 1 μL of the sample solution was taken with a microsyringe and introduced into GC / MS to quantify methyl ethyl ketone. The quantitative value was determined from a calibration curve prepared with MEK (m / z 57) and sec-Butyl acetone (m / z 56) in the SIM mode of GC / MS.
(4) Moisture content About 0.5 g of the sample was precisely weighed, dried by heating at 140 ° C. for 40 minutes, cooled in a desiccator, then weighed again, and the moisture content was calculated from the heat loss.

(Dehydrophobic organic solvent with temperature-controlled humidity air)

Example 1
3000 parts of wet cake of water-containing colorant-containing resin particles obtained in the toner mother particle preparation example was stirred for 3 minutes at 30 m / s in a 20 L Henschel mixer having a CK blade, and once stopped, the conditions were further changed for 3 minutes. Crushing was performed with stirring. Next, 15 parts of silica H05TX (Silica manufactured by Clariant Japan, BET specific surface area 50) was added and stirred at 10 m / s for 1 minute. The umbrella ratio of the crushed material of the obtained wet cake was 0.40 g / cc. Next, the pulverized product 44.8 kg (solid content 30 kg) was charged into Hosokawa Micron “Nauter Mixer NXV-1” (effective volume 100 L) equipped with the incidental facilities described in FIG. Air (gas I) conditioned at a humidity of 40 ° C. with a humidity of 90% was sent in with an air volume of 20 L / min · Kg and treated for 8 hours. At this time, the agitator was set to 3 rpm for revolution and 90 rpm for rotation. Then, it switched to vacuum drying and processed for 10 hours, the water | moisture content was removed and the dry powder of the colorant containing resin particle was obtained. When the obtained dried content was measured with Coulter Multisizer II, no tailing was observed, and no generation of aggregates due to drying was observed.

(Example 2)
Example 2 was performed in the same manner except that the relative humidity of the gas I in Example 1 was changed. When the obtained dried content was measured with Coulter Multisizer II, no tailing was observed, and no generation of aggregates due to drying was observed.

(Example 3)
Example 3 was performed by the same operation except that the air volume in Example 1 was changed from 20 L / min · Kg to 10 L / min / Kg. When the obtained dried content was measured with Coulter Multisizer II, no tailing was observed, and no generation of aggregates due to drying was observed.

Example 4
After performing drying under normal pressure and humidity control conditions under the same conditions as in Example 1, after feeding air conditioned and adjusted to 40 ° C. with a relative humidity of 5% and reducing the moisture content, Vacuum drying was performed. When the obtained dried content was measured with Coulter Multisizer II, no tailing was observed, and no generation of aggregates due to drying was observed.

(Comparative Examples 1 and 2)
Comparative Examples 1 and 2 were performed in the same manner except that the relative humidity of the gas I in Example 1 was changed. When the obtained dried content was measured with Coulter Multisizer II, no tailing was observed, and no generation of aggregates due to drying was observed.

(Comparative Example 3)
Drying was performed only by vacuum drying without feeding atmospheric pressure humidity gas. The stirring conditions were the same as in Example 1 while adjusting the jacket temperature so that the product temperature was 40 ° C. After removing the water over 10 hours, it was further vacuum dried at a high vacuum of 0.3 to 0.5 Kpa for 18 hours. When the obtained dried content was measured with Coulter Multisizer II, no tailing was observed, and no generation of aggregates due to drying was observed. Tables 2 and 3 show the conditions and evaluation results of the examples and comparative examples.

表２，３における、含水率と残存MEK量の関係を見ると、含水率の高い状態でMEKが効率よく低減していることがわかる。特に、実施例における高湿気流下では、原料は高湿状態を保持しており、MEKが有効に除去されている。一方、比較例１，２における低湿気流下では、原料は徐々に乾燥が進行し、含水率が顕著に低下している。この環境下ではMEKの低減効果が小さくなり、有効に除去されなくなっていることがわかる。また、気体ＩＩの送入による乾燥工程では、水分は有効に除去されるが、MEKはほとんど除去されないことがわかる。また、比較例３では減圧による乾燥のみを行っているが、実施例１〜４に比べ、同レベルの残存MEK量まで乾燥するのに多くの時間がかかることがわかる。

Looking at the relationship between the moisture content and the amount of residual MEK in Tables 2 and 3, it can be seen that MEK is efficiently reduced at a high moisture content. In particular, under the high-humidity airflow in the examples, the raw material maintains a high-humidity state, and MEK is effectively removed. On the other hand, under the low-humidity airflow in Comparative Examples 1 and 2, the raw material is gradually dried, and the moisture content is significantly reduced. It can be seen that under this environment, the effect of reducing MEK is reduced and is not effectively removed. Further, it can be seen that in the drying process by feeding gas II, water is effectively removed, but MEK is hardly removed. Moreover, although only the drying by pressure reduction is performed in the comparative example 3, it turns out that it takes much time to dry to the residual MEK amount of the same level compared with Examples 1-4.

The present invention can be used for OA devices that use toner such as copying machines, printers, and fax machines.

It is the schematic of the drying apparatus and incidental equipment used by this invention.

Explanation of symbols

1. 1. Gas (air) generator 2. 2. Gas (air) flow meter 3. Gas (air) thermometer 4. Steam (steam) generator 5. Steam (steam) flow meter 6. Steam (steam) thermometer Humidity control gas generator 8. 8. Humidity control gas flow meter Humidity control gas thermometer10. Humidity control gas hygrometer11. Humidity control gas supply port 12. Agitator 13. Dryer pressure gauge14. Dryer thermometer15. Stirring motor 16. Bug filter 17. (Vacuum) dryer body 18. Hot water production device 19. Condenser 20. Condensate receiving tank 21. Vacuum pump

Claims (7)

A binder resin and a colorant mainly composed of polyester resin, water solubility in the dissolution or dispersible 25 ° C. The polyester resin is a mixture comprising 0.1 to 30 wt% of a hydrophobic organic solvent, an aqueous Emulsified or suspended in a medium to form a suspension of colorant-containing resin particles , an electrolyte was added to the suspension to unite the colorant-containing resin particles, and after removal of the solvent, the colorant-containing resin particles A first step of separating and washing the aqueous medium to obtain water-containing colorant-containing resin particles,
Then the water-containing colorant-containing resin particles were charged into a dryer with a pressure can be reduced stirrer, with stirring by the stirrer at normal pressure, the temperature 30 to 60 ° C., a relative humidity adjusted to 70% to 100% The wet gas (I) is fed, and the hydrophobic organic solvent remaining in the water-containing colorant-containing resin particles is removed by the water contained in the gas (I), and then the water-containing colorant-containing resin the second step have successively rows, and BET specific surface area in the water-containing colorant-containing resin particles after the first step is completed for depressurizing remove moisture remaining on the surface of the particles or the water-containing colorant-containing resin particles under stirring 30 A method for producing a toner for developing an electrostatic image, comprising adding ~ 200 inorganic oxide . In the second step, later infeed of the gas (I) is completed, the water content of the hydrous colorant-containing resin particles in a gas relative humidity is moistened adjusted to 60% or less (II) 10 to 35% The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the toner is adjusted to a range of 1 to 5. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the relative humidity of the gas (I) is 80 to 100%. 4. The electrostatic charge image developing according to claim 1, wherein the temperature of the gas (I) when the gas (I) is fed into the dryer is 30 to 50 ° C. 5. Toner manufacturing method. The said 1st process performs the process of following (1-i), (1-ii), (1-iii), (1-iv), and (1-v) sequentially, Claim 1, 2, 3 or 4 A method for producing a toner for developing an electrostatic image according to any one of the above.
(1-i) a step of producing a mixture by dissolving or dispersing a polyester resin having a carboxyl group and a colorant in a hydrophobic organic solvent;
The (1-ii) it is mixed with water in the presence of the mixture a basic compound, containing the hydrophobic organic solvent and the polyester resin and the colorant, the colorant-containing resin particles, water soluble medium in Producing a suspension suspended in
(1-iii) Next, a step of producing a unity of the colorant-containing resin particles by adding a dispersion stabilizer to the suspension and then adding an electrolyte;
(1-iv) removing the hydrophobic organic solvent;
(1-v) A step of separating and washing the unity from the aqueous medium. The hydrophobic organic solvent has a solubility in water at 25 ° C. of 0.1 to 30% by mass, and the boiling point at normal pressure is not more than the boiling point of water. A method for producing a toner for developing an electrostatic charge image according to any one of 4 and 5. The method for producing a toner for developing an electrostatic charge image according to any one of claims 1, 2, 3, 4, 5 and 6, wherein the inorganic oxide having a BET specific surface area of 30 to 200 is silica .

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