JP2005105018A - Manufacturing method of fine resin particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of fine resin particles, whereby an organic solvent can be easily removed from a suspension without aggravating particle shape or particle size distribution. <P>SOLUTION: The manufacturing method of fine resin particles comprises a step of removing the organic solvent, under agitation and a reduced pressure, from a suspension comprising a mixed solution at least containing a resin and an organic solvent and an aqueous medium containing an inorganic dispersant. In this solvent removal step, the agitation peripheral speed is kept at 40 m/sec or lower until the solvent residue ratio reaches 60 wt.% or lower; and the in-system pressure is kept at -95 to -76 kPa from a point in time when the solvent residue ratio becomes 95 wt.% until a point of time when it becomes 60 wt.% or lower. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing resin fine particles, and particularly to a production method suitable for producing resin fine particles having a sharp particle size distribution.

  Resin fine particles are used in a wide range of applications such as electrophotographic toners, powder coatings, matting agents, antiblocking agents, chromatographic carriers, pharmaceutical carriers, gap modifiers, electrorheological fluids, and cosmetics. As a method for producing these resin fine particles, a mixed solution in which a resin and other compounding components are dissolved or dispersed in an organic solvent is dispersed and suspended in an aqueous medium, and the organic solvent is removed from the obtained dispersion by heating, decompression, or the like. Thus, a method for forming particles has been proposed (see, for example, Patent Document 1).

As a method for removing the organic solvent in this method, drying in liquid is performed to transfer the droplets in which the organic solvent is dispersed into the aqueous medium, and further, the organic solvent in the aqueous medium is heated and reduced in pressure to form a suspension. There is a method of removing the organic solvent by vaporizing it at the contact interface with the gas (see, for example, Patent Document 2). However, in these conventional methods, the particle size distribution is broadened by shearing on the suspension, the shape deteriorates due to the generation of pores on the particle surface (increase in specific surface area, etc.), and further, the voids inside the particles are generated. There were disadvantages such as a decrease in density.
Japanese Patent Laid-Open No. 5-127422 JP-A-7-152202

  This invention is made | formed in view of the above actual condition in a prior art. That is, an object of the present invention is to provide a method for producing resin fine particles capable of easily removing an organic solvent from a suspension without deteriorating the particle shape and particle size distribution.

  The present inventors disperse and suspend a mixed solution in which a resin and other compounding components are dissolved or dispersed in an organic solvent in advance in an aqueous medium, and remove the organic solvent from the obtained dispersion by heating, decompression, or the like. The present inventors have intensively studied how to make particles. As a result, in the step of removing the organic solvent from the suspension, the organic solvent can be easily obtained without deteriorating the particle shape and particle size distribution and lowering the particle density by carrying out under specific stirring and reduced pressure conditions. As a result, the present invention has been completed.

  That is, the present invention provides resin fine particles having a step of removing an organic solvent from a suspension of a mixed liquid containing at least a resin and an organic solvent and an aqueous medium containing an inorganic dispersant under stirring and reduced pressure conditions. In the solvent removal step, the stirring peripheral speed is set to 40 m / min or less until the solvent residual rate becomes 60% by weight or less until the solvent residual rate becomes 60% by weight or less from the time when the solvent residual rate becomes 95% by weight. Until this time, the system pressure is -95 to -76 kPa.

  According to the production method of the present invention, resin fine particles can be produced without deteriorating particle size distribution, particle shape, and particle density. As a result, when used for toner, a good quality image can be obtained, and when used for powder coating, a smooth and high gloss coating can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail. In the method for producing resin fine particles of the present invention, a mixed solution in which a resin and, if necessary, other blending components are dissolved or dispersed in an organic solvent is used. The resin used in the present invention is not particularly limited as long as it is dissolved or dispersed in an organic solvent and not dissolved in an aqueous dispersion medium (preferably having a solubility of 1% or less). For example, polyaddition resin, vinyl Polymerization resins, condensation resins, ring-opening polymerization resins, and the like can be used. The number average molecular weight of the resin ((Mn), according to gel permeation chromatograph (GPC), the same shall apply hereinafter) is preferably 1000 or more, more preferably 5000 or more, and the melting point is preferably 40 ° C. or more, more preferably 60 ~ 200 ° C.

  Examples of the polyaddition resins include polyurethane resins, and vinyl polymerization resins include (meth) acrylic resins, styrene resins, styrene- (meth) acrylic resins, polyolefin resins, and vinyl acetate resins. Resin etc. are mentioned. Examples of the condensation resins include polyester resins, polyamide resins, silicone resins, polycarbonate resins, phenol resins, melamine resins, and urea resins. Examples of ring-opening polymerization resins include polyether resins, polyacetal resins, and epoxy resins.

Preferred among these are polyurethane resins, (meth) acrylic resins, styrene resins, styrene- (meth) acrylic resins, polyolefin resins, polyester resins, polyamide resins, silicone resins, polyether resins and epoxy resins. More preferred are (meth) acrylic resins, styrene resins, styrene- (meth) acrylic resins, and polyester resins. These may be used alone or in combination of two or more.
These resins may be those usually used, and examples thereof include those described in JP-A No. 2002-226328 and JP-A No. 2002-284881.

In the present invention, the organic solvent used for dissolving or dispersing the resin includes esters such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate; ethers such as diethyl ether, dibutyl ether, dihexyl ether and tetrahydrofuran; methyl ethyl ketone and methyl isopropyl ketone. , Ketones such as methyl isobutyl ketone and cyclohexanone; aliphatic or aromatic hydrocarbons such as toluene, xylene and hexane; halogenated hydrocarbons such as dichloromethane, chloroform and trichloroethylene; These may be used independently or may mix 2 or more types.
These organic solvents can dissolve the resin (the amount of the resin dissolved in the solvent at 25 ° C. is preferably 10% or more), and the solubility in water at 25 ° C. is 0 to 30%. Is preferred. Further, when industrialization is performed, cyclohexane, ethyl acetate, and / or tetrahydrofuran are particularly preferable in consideration of work safety, cost, and productivity. In the above and the following, “%” means “% by weight” unless otherwise specified.
These organic solvents are preferably used such that the viscosity of a mixed solution obtained by dissolving or dispersing the resin and, if necessary, other compounding components in the organic solvent is in the range of 1000 to 30000 mPa · s at 25 ° C. Is in the range of 3000 to 20000 mPa · s. Further, the solid content of the mixed solution obtained by dissolving or dispersing the resin and other compounding components in an organic solvent (content in the mixed solution of components other than the organic solvent) is preferably 5 to 80%, more preferably 10 to 70%. It is.

In the present invention, a compounding component can be added to the resin mixed solution according to the use of the resin fine particles. For example, in the case of an electrophotographic toner, a colorant, a release agent, a charge control agent and the like may be appropriately blended (see, for example, JP-A No. 11-044969).
Although the addition amount with respect to resin of compounding components other than resin changes with kinds and uses of resin, Preferably it is 100% or less, More preferably, it is 5 to 80%. In particular, in the case of toner for electrophotography, it is preferably 50% or less, more preferably 5 to 30%.

  In the case of toner for electrophotography, as the colorant, carbon black, magnetic powder, organic pigments (cyan pigment, magenta pigment, yellow pigment, etc.) and other commonly used colorants for toner particles for developing electrostatic images Is mentioned. Examples of the release agent include petroleum wax, mineral wax, animal and plant wax, synthetic wax, and other agents usually used as a release agent for toner particles for developing electrostatic images. As the charge control agent, a quaternary ammonium salt compound or any other commonly used charge control agent for electrostatic image developing toner particles is used.

  In the case of powder coating applications, commonly used blending components for paints such as colorants, leveling agents, anti-blocking agents, ultraviolet absorbers, benzoin, antistatic agents, and antioxidants may be appropriately blended (for example, JP, 10-316896, A).

  Moreover, in the case of cosmetics use, you may mix | blend normally used compounding components, such as a coloring agent, a reinforcing agent, a matting agent, and an antiblocking agent suitably (for example, refer Unexamined-Japanese-Patent No. 2002-226328).

  In the present invention, a dispersion suspension obtained by dispersing or suspending a mixed solution obtained by dissolving or dispersing the above resin in an organic solvent in an aqueous medium containing an inorganic dispersant is used. This dispersion suspension is obtained by introducing the mixed liquid containing the resin into an aqueous medium containing an inorganic dispersant.

Examples of the inorganic dispersant used in the present invention include oxides (silica, alumina, titania, etc.), metal carbonates (calcium carbonate, magnesium carbonate, etc.), tricalcium phosphate, silicates (clay, diatomaceous earth, bentonite, etc.), etc. Can be mentioned. Of these, calcium carbonate is preferred.
Moreover, as for these inorganic dispersing agents, what the particle | grain surface is coat | covered with the polymer which has a carboxyl group is more preferable. By using a material coated with such a polymer, stable resin fine particles can be produced. Moreover, as said polymer which has a carboxyl group, it is preferable to use the thing of the range whose Mn is 1000-200000.
For example, a homopolymer of a carboxyl group-containing monomer such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, or a copolymer thereof, and other vinyl monomers (for example, as described in JP-A-2002-284881) (For example, the molar ratio of the carboxyl group-containing monomer is 10 to 99 mol%). The carboxyl group may be a metal salt such as sodium, potassium, magnesium, or an ammonium salt.

These inorganic dispersants are dispersed in an aqueous medium using a dispersing machine containing a medium such as a ball mill or a bead mill, a high-pressure dispersing machine, an ultrasonic dispersing machine, or the like.
The aqueous medium is composed of water and, if necessary, a water-soluble organic solvent. The water-soluble organic solvent is a solvent having a solubility in water at 25 ° C. of 5 or more (preferably 8 or more), and examples thereof include ethyl acetate, ethylene glycol, acetone, and methanol. Of these, ethyl acetate is preferred. The content of the water-soluble organic solvent in the aqueous medium is preferably 30% or less, more preferably 1 to 15%.
The average particle diameter after dispersion is preferably in the range of 1 to 1000 nm, more preferably 5 to 500 nm. The amount of the inorganic dispersant used is preferably in the range of 1 to 500 parts, more preferably 5 to 200, with respect to 100 parts of the mixed solution obtained by dissolving or dispersing the resin and other compounding components in an organic solvent. Part. Above and below, parts mean parts by weight.

  In order to make the particle size distribution of the resin fine particles uniform, it is preferable to disperse the inorganic dispersant in the aqueous medium and add a polymer dispersant that dissolves in water. These polymer dispersants may be added by any method as long as they are uniformly dissolved in the aqueous medium.

As the polymer dispersant, those having a weight average molecular weight (Mw) of 5,000 to 1,000,000 (by GPC) and capable of being dissolved in water at 25 ° C. at 0.5% or more are preferable. Among those having a carboxyl group, those having no hydroxypropoxyl group or methoxyl group are preferred. Specifically, water-soluble cellulose ethers such as carboxymethyl cellulose and carboxyethyl cellulose are preferable, and carboxymethyl cellulose is particularly preferable.
These celluloses preferably have an etherification degree of 0.6 to 1.5 and an average degree of polymerization of 50 to 3000. The carboxyl group may be a metal salt such as sodium or potassium. Also. The amount of the polymer dispersant used is preferably 50 parts or less, more preferably in the range of 0.2 to 20 parts, with respect to 100 parts of a mixed solution obtained by dissolving or dispersing the resin and the compounding components in an organic solvent. is there.
The weight ratio of the inorganic dispersant to the polymer dispersant is preferably 100: 0 to 100: 30, more preferably 100: 0.5 to 100: 15.

  An apparatus used for obtaining a dispersion suspension (in the present invention, an oil-in-water suspension) is particularly limited as long as it is generally commercially available as an emulsifier or a disperser. It is not a thing. For example, batch type emulsification such as TK auto homomixer, TK Robomix (manufactured by Tokushu Kika Kogyo Co., Ltd.), Ultra Turrax (manufactured by IKA), Polytron (manufactured by Kinematica), National Cooking Mixer (manufactured by Matsushita Electric Industrial Co., Ltd.) Machine: Ebara Milder (manufactured by Ebara Manufacturing Co., Ltd.), TK pipeline homomixer, TK homomic line flow (manufactured by Special Machine Industries Co., Ltd.), colloid mill (manufactured by Shinko Pantech Co., Ltd.), thrasher, trigonal wet milling machine ( Continuous emulsifiers such as Mitsui Miike Kako Co., Ltd., Cavitron (Eurotech Co., Ltd.), Fine Flow Mill (Pacific Kiko Co., Ltd.); Claremix (MTechnic Co., Ltd.), Fillmix (Special Kika Kogyo Co., Ltd.) ) Etc. batch or continuous dual-use emulsifiers; Microfluidizer (manufactured by Mizuho Kogyo Co., Ltd.) High-pressure emulsifiers such as Zer (manufactured by Nanomizer), APV gourin (manufactured by Gourin); membrane emulsifiers such as membrane emulsifier (manufactured by Chilling Industries Co., Ltd.); An ultrasonic emulsifier such as an ultrasonic homogenizer (manufactured by Branson);

In the suspension solvent removal step in the present invention, the organic solvent in the suspension is removed to obtain a resin fine particle dispersion without drying and solidifying the dispersion suspension. The solid content concentration of the suspension before removing the organic solvent (concentration of components other than the organic solvent and the aqueous medium) is preferably 1 to 60%, more preferably 5 to 40%. The organic solvent content in the suspension before removing the organic solvent is preferably 1 to 50%, more preferably 5 to 30%. The resin content is preferably 1 to 60%, more preferably 5 to 35%. The content of the aqueous medium is preferably 30 to 90%, more preferably 40 to 80%. The content of the inorganic dispersant is preferably 0.5 to 20%, more preferably 1 to 15%. The content of the polymer dispersant is preferably 5% or less, more preferably 0.01 to 2%.
The solvent removal of the suspension may be performed immediately after the preparation of the dispersion suspension, or after converging to stabilize the particles in order to sharpen the particle size distribution of the obtained resin fine particles. You may implement. Convergence is performed after the dispersion suspension step, for example, by placing the suspension in a temperature range of 5 to 40 ° C. for 1 minute to 6 hours. At this time, the suspension may be left stationary or may give a slow flow of 1 to 50 m / min.

In the production method of the present invention, as the organic solvent removing device used in the solvent removal step, a general stirring blade rotating type stirring tank capable of reducing pressure (excellent in airtightness) can be used. The shape of the stirring blade is not particularly limited, and a stirring blade such as a saddle type, a spiral type, or a max blend type can be used.
The number of stirring blades may be singular or plural (for example, 2 to 10). Further, the length of the stirring blade (from the center of rotation to the end) is preferably 80% or more, more preferably 90 to 99% of the distance from the center of rotation to the tank wall surface. The specific length of the stirring blade is not particularly limited as long as it can satisfy the peripheral speed in the production method of the present invention. For example, in the case of a vertical stirring device having a capacity of 10 kL, 0.7 to 1.2 m. Is preferred.

  In the solvent removal step in the production method of the present invention, the temperature of the suspension during solvent removal is not particularly limited as long as the temperature allows solvent removal, but is preferably 0 to 50 ° C, more preferably 10 to 10 ° C. 40 ° C. If the temperature of the suspension is 0 ° C. or higher, the solvent removal can be completed within a practical time, and if it is 50 ° C. or lower, the particle size distribution is hardly deteriorated due to aggregation.

  The pH of the suspension during solvent removal is preferably 6-11, more preferably 7-10. If the pH of the suspension is 6 or more, a good particle shape can be maintained, and if it is 11 or less, the particle size distribution is hardly deteriorated. In order to adjust the pH of the suspension to the above range, a commonly used acid or alkali can be added. This pH adjustment is preferably performed before the solvent removal step.

  In the solvent removal step in the present invention, it is necessary to suppress the stirring peripheral speed until the solvent residual ratio becomes 60% or less, preferably 50% or less. The stirring peripheral speed is 40 m / min or less, preferably 1 to 30 m / min. Here, the solvent residual ratio means the amount (%) of the organic solvent in the suspension with respect to the amount of the organic solvent before removing the organic solvent, and the peripheral speed is the outermost end portion of the stirring blade from the stirring shaft. Means peripheral speed. In a region where the solvent residual ratio is more than 60%, the oil droplets are unstable and shearing should be avoided as much as possible. When the stirring peripheral speed exceeds 40 m / min, this shear is large, and thus aggregates due to coalescence of particles may be generated to deteriorate the particle size distribution. Further, after the solvent residual ratio becomes 60% or less, preferably 50% or less, the oil droplets are stabilized, so that the stirring peripheral speed can be increased. The peripheral speed at this time is preferably 10 to 100 m / min, and more preferably 30 to 80 m / min.

  In the desolvation step, the internal pressure (until the solvent residual ratio reaches 60% or less, preferably 50% or less, excluding the initial stage of solvent removal (until the solvent residual ratio reaches 95% (preferably 98%)). The gas phase must be -95 to -76 kPa. Although it is difficult to set the internal pressure within the above range from the start of the desolvation because the desolvation speed becomes too fast, it is preferable to adjust the internal pressure as soon as possible after the start of the desolvation. If the system internal pressure is less than -95 kPa, the particle shape may be deteriorated due to rapid organic solvent removal from the droplets. On the other hand, when the system pressure exceeds -76 kPa, the rate of solvent removal becomes slow, and organic solvent removal is not completed in a practical process time on an industrial scale.

In the solvent removal step, the particle shape can be further improved by changing the internal pressure in accordance with the suspension temperature during the removal of the organic solvent, and the powder fluidity can be improved. In this case, the temperature of the suspension during removal of the organic solvent is 10 to 40 ° C., and the suspension is suspended until the organic solvent content of the suspension during removal of the organic solvent is 30% or less of that before the removal of the organic solvent. It is preferable to carry out the system pressure in a range satisfying the formula (1) depending on the temperature of
Y ≧ 0.0193X ² -0.4386X-90.887 (1)
[X represents temperature (unit: ° C.) and Y represents pressure (unit: kPa). 10 ≦ X ≦ 40]

  After the solvent residual ratio becomes 60% or less, since the particle shape is stabilized, the pressure inside the system can be lowered to increase the solvent removal rate [however, the above formula ( A range satisfying 1) is preferred. ]. In this case, the internal pressure is preferably −76 kPa or less, more preferably −80 kPa or less.

In the solvent removal step in the production method of the present invention, in order to increase the solvent removal rate, it is preferable to pass the carrier gas through the system during the organic solvent removal. As a carrier gas, general gases such as air, helium, nitrogen, and argon can be used singly or in combination of two or more, but air and nitrogen that can be used industrially at low cost are used alone or mixed. And preferably used.
The carrier gas may pass through either the gas phase or the liquid phase, or both may be used in combination. However, it is preferable that the initial stage of the solvent removal step is only the gas phase and the liquid phase is switched to the later stage. Switching from the gas phase to the liquid phase is preferably performed when the content of the organic solvent in the suspension is 70% or less, more preferably when the content of the organic solvent in the suspension is 60 to 40%.

The amount of carrier gas passed through the gas phase is preferably 0.1 to 50 L / min · 1000 kg, more preferably 0.5 to 30 L / min · 1000 kg. Here, “/ min · 1000 kg” means the amount of carrier gas that is allowed to pass in 1 minute per 1000 kg (1 t) of the suspension before the desolvation step. If the amount of carrier gas is 0.1 to 50 L / min · 1000 kg, the effect of improving the solvent removal rate can be obtained according to the flow rate.
Further, the amount of carrier gas when passing through the liquid phase is preferably 0.1 to 50 L / min · 1000 kg, more preferably 0.5 to 30 L / min · 1000 kg. If the amount of carrier gas is 0.1 L / min · 1000 kg or more, the effect of improving the organic solvent removal rate increases according to the flow rate, and if it is 50 L / min · 1000 kg or less, it is suspended near the gas inlet. The shear applied to the turbid liquid does not increase, and there is no possibility of agglomeration due to coalescence of particles to deteriorate the particle size distribution.

The content of the organic solvent in the resin fine particle dispersion after the desolvation step is preferably 5% or less, more preferably 2% or less.
In the method for producing resin fine particles in the present invention, steps such as washing and dehydration, drying, sieving, classification, and external addition are added as necessary after the above-mentioned solvent removal step. The washing and dehydration step is a step of obtaining a cake by removing the aqueous medium from the resin fine particle dispersion obtained in the solvent removal step, followed by washing and dehydration. In this washing and dehydration step, the inorganic dispersant used in the dispersion suspension step was mainly dissolved and removed (preferably until the remaining amount became 1% or less with respect to the resin fine particles). The resin fine particle dispersion is preferably acid-treated and then washed with water and dehydrated. However, an alkali treatment may be added after the acid treatment if necessary.
It does not specifically limit as an acid used for the said acid treatment, Although what is normally used industrially can be used, Preferably it is hydrochloric acid. The acid treatment pH is preferably 5 or less, more preferably 4 or less. It does not specifically limit as an alkali used for the said alkali treatment, Although what is normally used industrially can be used, Preferably they are ammonia and sodium hydroxide. The pH of the alkali treatment is preferably 7 or more, more preferably 8 or more.

  A drying process is a process of drying the cake obtained at the said washing | cleaning dehydration process, and obtaining powder. The drying process is not particularly limited as long as the resin fine particles do not cause aggregation or pulverization. For example, powder can be obtained by drying the cake at 30 to 60 ° C. for 2 to 30 hours using a circulating dryer. The moisture content in the resin fine particles after drying is preferably 2% or less.

  The sieving and classification step is a step of removing coarse powder, fine powder, and the like contained in the powder obtained by drying. The external addition step is a step of adding and mixing the other blending components to the powder in order to impart a function such as improving the fluidity of the obtained powder. These steps are not particularly limited as long as the resin fine particles do not cause aggregation or pulverization.

According to the production method of the present invention, resin particles having a sharp particle size distribution with a volume average particle size of 5 to 10 μm, a number particle size distribution GSDf of 2.0 or less, and a volume particle size distribution GSDc of 1.5 or less are easily produced. can do.
The resin fine particles obtained by the production method of the present invention include electrophotographic toners, powder paints, matting agents, antiblocking agents, chromatographic carriers, pharmaceutical carriers, gap adjusting agents, electrorheological fluids, cosmetics, etc. Although it can be used for a wide range of applications, it is particularly suitable for electrophotographic toners and powder coatings.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples at all.
<Manufacture of resin fine particles for toner>
<Example 1>
[Making a mixture]
90 parts of a polyester resin (Tg: 66 ° C., melting point: 106 ° C.) consisting of a bisphenol A propylene oxide 2 mol adduct, a bisphenol A ethylene oxide 2 mol adduct, and terephthalic acid (molar ratio 1: 1: 2). I. Pigment Blue 5 parts ・ Paraffin wax (melting point: 89 ° C.) 5 parts ・ Ethyl acetate 100 parts The above components were dispersed with an Ebara milder at 25 ° C. for 12 hours to obtain 200 parts of a toner material mixed solution in which the polyester resin was dissolved. .

[Creation of dispersion suspension]
60 parts of calcium carbonate (average particle size: 0.18 μm) coated with acrylic acid-maleic acid copolymer (Mn: 10000). Average polymerization degree 800-900, etherification degree 0.70-0.80 Carboxymethyl cellulose 2 parts-Ion exchanged water 238 parts The above components were dispersed with an Ebara milder at 25 ° C for 5 hours to obtain 300 parts of an aqueous medium. While 300 parts of the aqueous medium were being stirred at 8000 rpm using a TK auto homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), 200 parts of the toner material mixed solution was charged. The mixture was stirred for 10 minutes at 25 ° C. and then stopped to obtain 500 parts of a suspension.

[Desolvation step]
After 500 parts of the suspension obtained in the dispersion suspension step was allowed to stand at 25 ° C. for 10 minutes, a vertical stirrer (stirring blade length: 1.0 m), cooling trap, jacket, carrier gas introduction pipe, pressure It moved to the organic solvent removal tank equipped with the controller and the vacuum pump, and the organic solvent removal was performed on the conditions shown below. The organic solvent content after desolvation was 0.3%.
<Organic solvent removal conditions>
Stirring peripheral speed (solvent residual ratio 50% or more): 30 m / min Stirring peripheral speed (solvent residual ratio less than 50%): 70 m / min Jacket hot water temperature: 35 ° C.
Suspension temperature: 30 ° C
In-system pressure: −85 kPa ± 1 kPa [right side of formula (1): −86.7] (except immediately after the start of desolvation)
Carrier gas (nitrogen) flow rate (solvent residual rate of 60% or more): gas phase 5 L / min · 1000 kg suspension Carrier gas (nitrogen) flow rate (solvent residual rate of less than 60%): liquid phase 5 L / min · 1000 kg suspension

[Washing, dehydration]
To 200 parts of the toner dispersion obtained in the solvent removal step, 40 parts of 10N hydrochloric acid was added and stirred for 15 minutes, followed by pressure filtration. Furthermore, ion-exchange water washing by pressure filtration was repeated 4 times to obtain a cake.
[Drying, sieving]
The cake obtained in the dehydration step was dried in an oven at 50 ° C. and sieved with a wire mesh having an opening of 45 μm to obtain a toner for developing an electrostatic charge image except for particles having a particle diameter exceeding 45 μm. The water content was 0.2%.

<Example 2>
In the method of Example 1, a toner for developing an electrostatic charge image was prepared in the same manner as in Example 1 except that the carrier gas (nitrogen) flow rate at a solvent residual ratio of less than 60% was changed to a liquid phase of 8 L / min · 1000 kg. Obtained.

<Example 3>
In the method of Example 1, an electrostatic charge image developing toner was obtained in the same manner as in Example 1 except that the system pressure in the solvent removal step was -82 kPa ± 1 kPa.

<Comparative Example 1>
In the method of Example 1, an electrostatic charge image developing toner was obtained in the same manner as in Example 1 except that the stirring peripheral speed was 50 m / min when the solvent residual rate was 50% or more.

<Comparative example 2>
In the method of Example 1, an electrostatic charge image developing toner was obtained in the same manner as in Example 1 except that the system pressure in the solvent removal step was -97 kPa ± 1 kPa.

For the toners obtained in Examples 1 to 3 and Comparative Examples 1 to 2, the volume average particle size and number particle size distribution GSDf (D50n / D84n) using Multisizer 3 type (manufactured by Beckman Coulter, Inc.) are used. ), Measurement result of volume particle size distribution GSDc (D16v / D50v), particle shape evaluation result observed with SEM (scanning electron microscope), apparent density and powder tester PT-R type (manufactured by Hosokawa Micron) Table 1 shows the measurement results of the powder compression ratio (ratio of loose apparent density and apparent apparent density).
In this particle size evaluation, the volume average particle size is preferably 5 to 10 μm. The number particle size distribution GSDf is preferably 2.0 or less. The volume particle size distribution GSDc is preferably 1.5 or less. The powder compression ratio is an index of powder fluidity, and if the compression ratio is 0.5 or less, good powder fluidity is exhibited.

The criteria for the evaluation of the particle shape are as follows.
A: No irregularities are observed on the particle surface.
○: There are few irregularities on the particle surface.
X: There are many irregularities on the particle surface.

The apparent density measurement conditions and criteria are as follows.
It measured using the said powder tester on the conditions of a cup capacity | capacitance of 25 ml and the tapping frequency of 180 times (1 time / second) (unit: g / cm < ³ >), and determined by the following references | standards.
◎: 0.540 or more ○: 0.510 or more and less than 0.540 ×: Less than 0.510

The toners obtained in Examples 1 to 3 and Comparative Examples 1 to 2 were externally added according to the following procedure, and the charge amount was measured by the blow-off method.
[External processing]
100 parts of toner and 1 part of silica R972 (manufactured by Nippon Aerosil Co., Ltd.) were mixed using a Hensyl mixer to obtain an externally added toner.
[Charge measurement]
8 parts of externally added toner and 100 parts of 50 μm ferrite carrier coated with PMMA were mixed in a low temperature and low humidity environment with a temperature of 10 ° C. and a humidity of 15%, and the charge amount of the toner was measured by a blow-off method. Similarly, the mixture was mixed in a high-temperature and high-humidity environment with a temperature of 28 ° C. and a humidity of 80%, and the charge amount was measured. The measurement results are shown in Table 2.

  In Comparative Examples 1 and 2, the charge amount was lower than in Examples 1 to 3. This is considered to be the effect that the powder flowability deteriorated due to the deterioration of the particle size distribution and particle shape.

<Manufacture of fine resin particles for powder coatings>
<Example 4>
[Creating a mixture]
Resin (Tg: 51 ° C., Mn: 4000) composed of glycidyl methacrylate, methyl methacrylate, butyl acrylate, styrene copolymer (molar ratio 21: 26: 8: 45) and diphenyl phosphite (0.2%) 60 parts 1, 11-dodecanedioic acid 11 parts Leveling agent (Modaflow; manufactured by Monsanto) 0.5 parts Benzoin 0.5 parts Titanium oxide 28 parts Ethyl acetate 100 parts By stirring for 8 hours, 200 parts of a powder coating material mixed solution in which the resin was dissolved was obtained.

[Creation of dispersion suspension]
40 parts of calcium carbonate (average particle size: 0.18 μm) coated with an acrylic acid-maleic acid copolymer (Mn: 10000). Average polymerization degree 800 to 900, etherification degree 0.70 to 0.80 Carboxymethylcellulose 2 parts-Ion-exchanged water 258 parts The above components were dispersed with an Ebara milder for 5 hours to obtain 300 parts of an aqueous medium. While 300 parts of this aqueous medium were being stirred at 8000 rpm using a TK auto homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), 200 parts of the powder coating material mixed solution was charged. After stirring for 10 minutes, the operation was stopped to obtain 500 parts of a suspension.

[Desolvation step]
After leaving 500 parts of the suspension obtained in the dispersion suspension process for 10 minutes, a vertical stirring device (agitating blade length 1.0 m), cooling trap, jacket, carrier gas introduction tube, pressure controller and vacuum It moved to the organic solvent removal tank equipped with the pump, and organic solvent removal was performed on the conditions shown below. The solvent content after desolvation was 0.2%.
<Organic solvent removal conditions>
Stirring peripheral speed (solvent residual ratio 50% or more): 30 m / min Stirring peripheral speed (solvent residual ratio less than 50%): 70 m / min Jacket hot water temperature: 35 ° C.
Suspension temperature: 30 ° C
In-system pressure: −85 kPa ± 1 kPa [right side of formula (1): −86.7] (except immediately after the start of desolvation)
Carrier gas (nitrogen) flow rate (solvent residual rate of 60% or more): gas phase 5 L / min · 1000 kg suspension Carrier gas (nitrogen) flow rate (solvent residual rate of less than 60%): liquid phase 5 L / min · 1000 kg suspension

[Washing, dehydration]
To 200 parts of the toner dispersion obtained in the solvent removal step, 40 parts of 10N hydrochloric acid was added, stirred for 15 minutes, and then filtered under pressure. Further, ion-exchange water washing by pressure filtration was repeated 4 times to obtain a powder coating cake.
[Drying, sieving]
The cake obtained in the dehydration step was dried in an oven at 40 ° C. and sieved with a wire mesh having an opening of 150 μm to obtain a powder paint except for particles having a particle diameter exceeding 150 μm. The water content was 0.4%.

<Comparative Example 3>
In the method of Example 4, a powder coating material was obtained in the same manner as in Example 4 except that the stirring peripheral speed at a solvent residual ratio of 50% or more was changed to 50 m / min.

<Comparative example 4>
The same powder coating material as that used in Example 4 was melt-kneaded under a condition of 110 ° C. using a biaxial extruder “Ikegai PCM30 type” (Ikegai Iron Works Co., Ltd.). After cooling, the mixture was pulverized with a pulverizer and sieved with a 150 μm mesh to prepare a powder coating material except for particles having a particle diameter exceeding 150 μm.

The following items were evaluated for each powder paint obtained in Example 4 and Comparative Examples 3 and 4. The evaluation results are shown in Table 3.
1) Coating film smoothness A zinc phosphate-treated steel sheet was coated using an electrostatic coating machine for powder coating, and baked at 180 ° C. for 20 minutes to obtain a test plate. The smoothness of the coated surface having a film thickness of 40 to 60 μm was visually determined based on the following criteria.
○: Smooth with no unevenness Δ: Slightly uneven ×: With unevenness on the entire surface 2) Pellet flow A metal plate formed by shaping 0.5 g of powder coating into pellets with a diameter of 15 mmφ and tilting to 45 ° The sample was placed on top and placed in an atmosphere at 170 ° C. for 20 minutes, and the length (mm) of the flow-off was measured.
3) Measurement of gloss (60 degree gloss) of coating film It was evaluated according to JIS K5400 7.6.

Claims (5)

A method for producing resin fine particles, comprising a step of removing an organic solvent from a suspension of a mixed liquid containing at least a resin and an organic solvent and an aqueous medium containing an inorganic dispersant under stirring and reduced pressure conditions. In the solvent step, the stirring peripheral speed is set to 40 m / min or less until the solvent residual rate becomes 60% by weight or less, and the pressure inside the system until the solvent residual rate becomes 95% by weight or less until the solvent residual rate becomes 60% by weight or less. -95 to -76 kPa, A method for producing resin fine particles. In the desolvation step, the temperature of the suspension during the removal of the organic solvent is 10 to 40 ° C., and the temperature of the suspension is reduced from the time when the solvent residual ratio becomes 95% by weight to 30% by weight or less. 2. The method for producing resin fine particles according to claim 1, wherein the method is carried out at an in-system pressure Y (unit: kPa) satisfying the relationship of the following formula (1) according to X (unit: ° C.).
Y ≧ 0.0193X ² -0.4386X-90.887 (1)
(However, 10 ≦ X ≦ 40) 3. The method for producing resin fine particles according to claim 1, wherein in the solvent removal step, a carrier gas is passed through the gas phase and / or the liquid phase during the removal of the organic solvent. 4. The fine resin particles according to claim 3, wherein in the desolvation step, the carrier gas is passed through the gas phase in an initial phase of 0.1 to 50 L / min · 1000 kg, and the latter phase is passed in a liquid phase of 0.1 to 50 L / min · 1000 kg. Manufacturing method. The resin fine particles according to any one of claims 1 to 4, wherein the obtained resin fine particles have a volume average particle size of 5 to 10 µm, a number particle size distribution GSDf of 2.0 or less, and a volume particle size distribution GSDc of 1.5 or less. Method.