JP2973234B2 - Manufacturing method of microcapsules - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Background of the Invention]

The present invention relates to a method for producing microcapsules. In particular, it relates to a method for producing a toner having a multilayer structure.

[0002]

2. Description of the Related Art At present, attention is being paid to the use of microcapsules as functional particles in many technical fields. For example, with respect to image forming toners, higher performance of the toners is required, and various methods for producing toners having a multilayer structure have been proposed. For example, a method for producing a microcapsule toner by a polymerization method mainly for the purpose of fixing with low energy (US Pat. No. 3,080,250, JP-B-59-310)
No. 66, JP-B1-36934, etc.) and a method for producing a toner having a charge control resin film layer for the purpose of charge control on the outer periphery of the toner using a dry high-speed impact method (Japanese Patent Application Laid-Open No. Sho 63-163). No. 62666), and a method for producing a toner in which fine resin powder is treated on the toner surface for the purpose of blocking resistance (Japanese Patent Application Laid-Open No. 1-105261).

However, in the case of using a high-speed collision force or an impact force as a method of fixing the coating layer to the toner (JP-A-63-62666, JP-A-1-105261), the toner surface The adhesion of the coating layer is weak,
In addition, there is a problem in that the coating layer deteriorates during use due to large variations in film thickness and adhesive force, peeling of the coating layer from the toner surface, change in surface shape, and the like, resulting in deterioration of image quality. Was. Further, a coating method by a microcapsule method (Japanese Patent Publication No. 59-31066, Japanese Patent Publication No. 62-611)
No. 41) has a similar problem, and there is a problem in the durability and the cohesion stability of the toner due to a thin coating layer and a large variation.

In many conventional methods, heat or pressure is used for attaching and fixing the coating layer to the inner core of the toner.
The toner core and the coating layer must be able to withstand them. Therefore, there is also a problem that the materials of the inner core of the toner and the coating layer are limited.

[0005] Generally speaking, in various technical fields, it is desired to develop a method for producing microcapsules capable of forming various coating layers on various inner cores at an arbitrary thickness and uniformly controlling them. ing.

[Summary of the Invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing microcapsules capable of forming various coating layers on various inner cores at a desired thickness and uniformly. And

Another object of the present invention is to provide a microcapsule in which the coating layer of the microcapsule is continuous over the entire circumference and has excellent strength and durability.

[0008]

That is, the method for producing microcapsules according to the present invention comprises the following steps (a) to (e).
It is what comprises. (A) A step of preparing an inner core of a microcapsule. (B) a step of uniformly adhering the resin particles to the surface of the inner core of the microcapsule, and using the inner core as the inner core of the resin particles; (C) a step of converting the inner core of the resin particles to primary particles. (D) a step of bringing the inner core of the resin particles adhered in a primary particle state into contact with a solvent capable of dissolving the resin of the resin particles; (E) a step of drying the inner core of the resin particles adhered to the solvent after contacting with the solvent in a state of primary particles, and thereafter recovering the core.

[Detailed Description of the Invention] The method for producing microcapsules according to the present invention comprises the above-mentioned steps (a) to (e).

Step (a) This step is a step of preparing an inner core of a microcapsule produced by the method for producing a microcapsule according to the present invention.

The method according to the present invention is applicable not only to the case where the inner core of the microcapsule is in a solid state, but also to the case where it is in a liquid state. Therefore, according to the present invention, many kinds of microcapsules can be microencapsulated, and at present, those that can be encapsulated as an inner core by other microcapsule manufacturing methods, such as toners, drugs, liquid crystals, and adhesives , Paints, printing inks, cosmetics, fragrances,
In the present invention, an agricultural chemical or the like can be used as the core of the microcapsule. In addition, since the method for producing a microcapsule according to the present invention does not require a large heat or pressure when attaching and immobilizing a coating layer on the surface of the inner core as described later, the material and condition of the inner core of the microcapsule are not required. Restrictions are greatly relaxed. Therefore, it is possible to microencapsulate what was practically impossible to microencapsulate in the conventional method.

Step (b) This step is a step in which resin particles are uniformly attached to the surface of the inner core of the microcapsule prepared in the previous step (a), and this inner core is used as the inner core of the resin particles. The method of attaching the resin particles in this step is not limited as long as the resin particles can be uniformly attached to the inner surface of the core of the microcapsule and the state of attachment, for example, the number of layers of the attached particles, can be controlled. . According to the method of the present invention, when the resin particles are brought into contact with the solvent in the step (d) described below, the adhered resin particles form a uniform coating layer. The thickness of this coating layer is proportional to the amount of the adhered resin particles. Therefore, a method in which only one resin particle is uniformly adhered to the inner core surface is particularly preferable because the thickness of the coating layer can be controlled by controlling the size of the resin particle, that is, the particle size.

The method of attaching the resin particles includes a dry method of attaching the resin particles in a dry state and a wet method of attaching the resin particles in a solvent.

Examples of the dry method include a method using a general mixer (eg, a ball mill, a V-type mixer), a method using a mechanochemical reaction (eg, a method using a high-speed fluidized stirrer), a powder bed method, and a fluidized bed method. No. In particular, a mechanochemical reaction using a high-speed fluidized stirrer is preferable because the number of adhering layers of resin particles can be easily controlled.
A so-called Hensyl mixer,
Preferable examples include a mechanofusion system (manufactured by Hosokawa Micron Co., Ltd.), a oak hybridization system (manufactured by Nara Machinery Co., Ltd.), and a mechanomill (manufactured by Okada Seiko Co., Ltd.).

Examples of the wet method include a wet milling method in which a dispersion solvent in which an inner core and resin particles are dispersed is milled by a ball mill or the like, a hetero-aggregation method using electrostatic adhesion due to a zeta potential difference between the inner core surface and the resin particle surface, an inner core. A coupling agent method in which resin particles are bonded to the surface via a coupling agent is exemplified.

Here, the heteroaggregation method is specifically described in J.
Colloid and Interface Sience, 109, 69-78 (1986). That is, the inner core and the resin particles are dispersed in water such that each has a different sign of zeta potential. Then, by mixing these two dispersion liquids, the resin particles having a small particle diameter adhere to the surface of the inner core having a large particle diameter by electrostatic force, thereby forming an inner core to which the resin particles are attached. This method is advantageous in that resin particles can be adhered to an inner core made of a soft substance that is difficult to handle by a dry method since an external force is not required when the inner core and the resin particles are adhered. Therefore, a powder made of a soft material such as wax, rubber, or elastomer, or a droplet made of a hydrophobic liquid dispersed in water can be used as the core of the microcapsule. In addition, in the coupling method, for example, a coupling agent is added to the inner core or surface-treated and attached to the surface, while the resin particles have a functional group capable of reacting with the functional group of the coupling agent. Causes resin particles to adhere.

Step (c) This step is a step in which the resin particle-adhered inner core obtained in the step (b) is brought into a state where the inner cores are not in physical contact with each other, that is, a state of primary particles. is there. The method is not particularly limited as long as the resin particle-attached inner core can be present in a state where the resin particle-attached inner core is not in contact with each other. Examples thereof include a method of dispersing in a liquid.

Step (d) This step is a step of bringing the inner core of the resin particles adhered into the state of primary particles in the above step into contact with a solvent capable of dissolving the resin of the resin particles. Here, the “solvent capable of dissolving the resin of the resin particles” means a solvent capable of forming a uniform layer of the resin on the inner core surface of the toner by dissolving the resin particles after contacting the resin particles and evaporating the solvent. Used in The solvent used in the present invention may be appropriately selected depending on the resin constituting the resin particles, the solubility of the resin in the solvent, the contact method and the contact time.

The method of contacting the resin particle-adhering inner core with the solvent is not limited as long as the resin particle-adhering inner core in the state of primary particles can be brought into contact with the solvent and the contact is uniform. A method capable of controlling time is preferred. Specifically, for example, a method of spraying a solvent into a space in which gas-conveyed inner cores of resin particles are present in a primary particle state, a method of dispersing inner cores of resin particles in a solvent, and a method of dispersing inner cores of resin particles with resin of resin particles. A method of dispersing in a liquid that does not dissolve and spraying a solvent in the space where the dispersion is sprayed,
A method in which the inner core of the resin particles adheres to or penetrates the wall of the solvent ejected in the form of a curtain, a method in which the inner core of the resin particles adheres to and mixes the liquid agent ejected in the form of a liquid column, a thin layer of the solvent flowing on the support And a method of colliding an inner core with resin particles attached thereto. The method of spraying the solvent onto the resin particle-attached inner core in a gas-conveyed and primary particle state can minimize the contact time between the resin particle-attached inner core and the solvent. This is a particularly preferable method in the case of dissolving resin particles having a small particle diameter. In addition, the method of dispersing the inner core of the resin particles attached to the solvent is preferable in that the primary particle forming step in the step (c) can be performed at the same time. In addition, the method of dispersing the inner core of the resin particles in a liquid that does not dissolve the resin of the resin particles and spraying the solvent into the space where the dispersion liquid is sprayed has a weak adhesion between the resin particles and the inner core, and forms primary particles by gas transport. Can be preferably applied to a resin particle / inner core system in which the resin particles may peel off from the inner core to which the resin particles adhere.

Preferred examples of the apparatus for carrying out this step include an apparatus equipped with a nozzle described later, a known spray dryer, a coatmizer (manufactured by Freund Corporation), a dispacoat (manufactured by Nisshin Engineering), and the like. .

Step (e) The inner core of the resin particles adhered to the solvent in the above step is:
The resin particles on the surface are attached to the inner core surface in a state of being dissolved in the solvent. This step is a step of evaporating the solvent of such particles to form a uniform resin coating layer on the inner core surface. At that time, in order to prevent the particles from aggregating, it is essential to evaporate the solvent in the state of the primary particles. As a specific method, for example, there is a method of evaporating the solvent by gas-transporting the inner core of the resin particles adhered to the primary particles after being gas-conveyed and then contacting with the solvent for a certain period of time. In this case, if necessary, the gas may be conveyed by a heated gas. Also, in the step (d), a spray drying method in which the dispersion in which the resin particle-adhered inner core is dispersed is sprayed to evaporate the solvent, or a maki drying method in which this dispersion is passed through and then dried, may be used. It is possible.

The particles dried in this way are then recovered as microcapsules. The collection can be performed by a known particle collection method and a known apparatus, for example, a cyclone.

Microcapsule Manufacturing Apparatus FIG. 1 is a schematic view of a preferred apparatus for carrying out the microcapsule manufacturing method according to the present invention. In FIG. 1, 1
Is a powder mixing device for adhering resin particles to the surface of the core inside the microcapsule. The resin core attached to the resin particles obtained in 1 is supplied to the mixing device 4 by the powder supply device 2. On the other hand, the solvent is supplied to the mixing device 4 by the solvent supply device 3. Further, a gas for transport is supplied to the mixing device 4 from the device 5. The mixing device 4 is a device for performing the drying steps (c), (d) and (e) according to the present invention. 2 and 3 show specific examples of the mixing device 4. FIG. 2 and 3, P indicates an inner core of resin particles attached, S indicates a solvent, G indicates a gas, and M indicates a mixture of the three. The device in FIG. 2 is a so-called nozzle, which has three inlets and an outlet from which the mixture M is injected. As shown in FIG.
In addition to the modes in which the solvent and the carrier gas are supplied from different inlets, as shown in FIGS. 2B to 2D, any two of the three are mixed and supplied in advance. It is also possible. In the nozzle of FIG. 2, these three can mix inside the nozzle. In addition, FIG.
(D) is a so-called nozzle as in FIG. 2, but another discharge port is provided on the outer peripheral portion of one discharge port.
The substances ejected from the two discharge ports are mixed on the extension of the discharge direction of the two discharge ports. In the apparatus of FIG. 3, any two of the three cores of the resin particle adhesion inner core, the solvent, and the carrier gas are mixed in advance and supplied to the inlets communicating with the two discharge ports. In the nozzle of FIG. 3, the three components are finally mixed outside the nozzle.

The inner core of the resin particles adhered to the solvent by the mixing device 4 is gas-conveyed from the discharge port of the nozzle to a certain space, that is, to the drying device 6. During this gas transfer, the solvent evaporates, and a uniform resin coating layer is formed on the inner core surface.

The microcapsules thus produced are collected by the collecting device 7.

[0026] To illustrate the preparation of toner having a multilayer structure using the method for producing microcapsules according to the invention in the following production of the toner having a multilayer structure.

FIG. 4 shows a toner manufacturing process by the dry method, and FIG. 5 shows a toner manufacturing process by the wet method.

First, a method of manufacturing a toner by a dry method will be described with reference to FIG. First, a toner core corresponding to the microcapsule core is prepared. The toner core may constitute the inside of a conventional toner having a multilayer structure. For example, a toner containing a binder component, a colorant, and other toner components such as a charge control agent, a magnetic powder, a conductive agent, a fluidity improver, a release agent, and a dispersant may be used. The core of the toner can be manufactured from these raw materials using a conventional method. For example, in addition to a kneading and pulverization method in which these materials are mixed, kneaded and finely pulverized, a spray drying method, a polymerization method and the like can be used.

The size of the inner core of the toner can be appropriately determined in consideration of its use conditions and the like.
m is preferred.

The binder component of the core of the toner is preferably a resin. Examples of the binder resin include polystyrene and copolymers such as hydrogenated styrene resin, styrene / isobutylene copolymer, ABS resin and ASA resin. ,
AS resin, AAS resin, ACS resin, AES resin, styrene / P-chlorostyrene copolymer, styrene / propylene copolymer, styrene / butadiene crosslinked polymer, styrene / butadiene / chlorinated paraffin copolymer, styrene / allyl alcohol Copolymer, styrene / butadiene rubber emulsion, styrene / maleic acid ester copolymer, styrene / isobutylene copolymer, styrene /
Maleic anhydride copolymer, acrylate resin or methacrylate resin and its copolymer, styrene / acrylic resin and its copolymer, for example, styrene / acrylic copolymer, styrene / diethylamino / ethyl methacrylate copolymer Styrene / butadiene / acrylate copolymer, styrene / methyl methacrylate copolymer, styrene / n-butyl methacrylate copolymer, styrene / diethylamino / ethyl methacrylate copolymer, styrene / methyl methacrylate / n -Butyl acrylate copolymer, styrene / methyl methacrylate / butyl acrylate / N- (ethoxymethyl) acrylamide copolymer, styrene / glycidyl methacrylate copolymer, styrene / butadiene / dimethyl / a Noethyl methacrylate copolymer, styrene / acrylate / maleate copolymer, styrene / methyl methacrylate / 2-ethylhexyl acrylate copolymer, styrene / n-butyl acrylate / ethyl glycol methacrylate copolymer Copolymer, styrene / n-butyl methacrylate / acrylic acid copolymer, styrene / n-butyl methacrylate / maleic anhydride copolymer, styrene / butyl acrylate / isobutyl maleic acid half ester / divinylbenzene copolymer, polyester and The copolymer,
Polyethylene and its copolymer, epoxy resin, silicone resin, polypropylene and its copolymer, fluorine resin, polyamide resin, polyvinyl alcohol resin, polyurethane resin, polyvinyl butyral resin, etc. Can be used.

Further, as a binder component, wax or the like can be used as a substance other than the resin. For example, natural plant-based waxes such as candelilla wax, carnauba wax, and rice wax, animal-based natural waxes such as beeswax and lanolin, mineral-based natural waxes such as montan wax and ozokerite, paraffin wax, microcrystalline wax, and natural petrolatum. Synthetic hydrocarbon waxes such as petroleum wax, polyethylene wax, Fischer-Tropsch wax, modified waxes such as montan wax derivatives and paraffin wax derivatives, hydrogenated waxes such as hardened castor oil and hardened castor oil derivatives, waxes such as synthetic waxes, stearin Acids, higher fatty acids such as palmitic acid, low molecular weight polyethylene,
One or more polyolefins such as polyethylene oxide and polypropylene, and olefin copolymers such as ethylene / acrylic acid copolymer, ethylene / acrylic acid ester copolymer, and ethylene / vinyl acetate copolymer can be used.

As the coloring agent, black dyeing / content such as carbon black, spirit black and nigrosine can be used. For color, phthalocyanine,
Dyes or pigments such as Rhodamine B lake, Solar Pure Yellow 8G, quinacridone, polytungstophosphoric acid, indaslen blue, and sulfonamide derivatives can be used. Further, as a dispersant, metal soap,
As a charge controlling agent such as polyethylene glycol, an electron-accepting organic complex, chlorinated polyester, nitrophenic acid, a quaternary ammonium salt, a pyridinyl salt, or the like can be added. In addition, magnetic powders for magnetic toner, for example, Fe ₃ O ₄ , Fe ₂ O ₃ , Fe, Cr, N
i or the like can be used.

The material of the resin particles adhered to the surface of the inner core of the toner is not limited as long as it can be dissolved in a solvent to be processed later. Therefore, it is possible to use resin particles of a material capable of imparting desired characteristics to the obtained toner. Conventionally, the resin used as a binder component of the inner core of the toner can also be used without limitation in the present invention as long as it can be dissolved in the solvent used. Furthermore, polyols such as polyvinyl alcohol, polyallyl alcohol, polybenzyl alcohol, and polyhydroxyethyl methacrylate; polyvinylamines such as polyvinylpyrrolidone, polyvinylpyridine, polyvinylamine, and polyallylamine; polyacrylamide, polyacrylic acid, and polymethacrylic acid. Acrylic derivatives,
Polylactic acid, casein, hydroxypropylcellulose,
Resin particles composed of a water-soluble resin such as methyl cellulose, carboxymethyl cellulose, gelatin, starch, gum arabic, natural polymers such as polyglutamic acid and polyaspartic acid can also be used.

Since the size of the resin particles determines the thickness of the coating layer obtained as described above, the particle size of the resin particles is determined from this viewpoint. For example, a particle size of about 0.05 to 15 μm is preferable.

Further, the resin particles may contain a third component for the purpose of improving the properties of the toner.
The third component may be attached to the inner core of the toner simultaneously with the resin particles as particles separate from the resin particles. Such third components include SiO ₂ , TiO ₂ , (rutile,
Anatase), ZnO, Al ₂ O ₃ (α-type, β-type), T
iON, TiBaO ₃ , MgO, ZrO ₂ , CaC
Fine particles such as O ₃ , NiO, SnO, clay, talc, silica sand, mica, SiN, SiC, Ba ₂ SO ₄ , carbon black and the like can be mentioned. These are added in order to improve the powder properties of the toner, particularly, fluidity, chargeability, moisture resistance, and storage stability.

The solvent to be used is appropriately selected depending on the type of the resin constituting the resin particles. Both aqueous and organic solvent systems can be used. The combination of the resin particles and the solvent can be selected, for example, using the solubility parameter as an index. Examples of the material of the resin particles and the range of the solubility parameter of the preferred solvent are as shown in the following table.

[0037] Solvent solubility parameter resin Hydrogen bond strength Weak hydrogen bond strength Hydrogen bond strength Strong vinyl resin 8.9-12.7 7.4-13.3 9.5-14.5 (Styrenes, acrylics) Polyester resin 8.9-11.6 9.3-11.1. Unfavorable epoxy resin 8.5- 12.7 7.4 to 14.7 9.5 to 14.5 Silicon resin 7.0 to 9.5 7.4 to 10.8 9.5 to 11.4 Fluoro resin Not preferred 7.4 to 10.3 9.2 to 14.5 Polyamide resin 8.5 to 11.1 7.4 to 12.1 8.9 to 12.7 Polyurethane resin 8.5 to 10.3 7.4 to 12.4 9.3 to 12.0 Water-soluble resin Unfavorable Unfavorable 9.0-24.5 Here, the hydrogen bonding strength of the solvent is described in NM Bikales, Encyc
lopedia of PolymerSience and Technology, vol.12, P
600 to 625, wiley, 1970. Specific examples of these solvents together with their solubility parameters are shown below. N-hexane (7.42), heptane (7.2)
4), hydrocarbons such as cyclohexane (8.18), aromatic hydrocarbons such as benzene (9.15), toluene (8.91), xylene (8.8 to 9.0), dichloromethane (9 .88), chloroform (9.24), tetrachloromethane (8.58), dichloroethane (9.9)
Halogenated hydrocarbons such as chlorobenzene (9.51) and the like, and nitromethane (12.7) and acetonirolyl (11.1) as solvents having an intermediate hydrogen bonding force.
8), nitrogen compounds such as acrylonitrile (10.5),
Tetrahydrofuran (9.32), dioxane (9.7
3), ethers such as methylcellosolve (10.8),
Esters such as ethyl acetate (9.04) and butyl acetate (8.5); ketones such as acetone (9.71), methyl ethyl ketone (9.04) and cyclohexanone (9.26); Examples of the solvent having a hydrogen bonding force include alcohols such as methanol (14.5), ethanol (12.9), propanol (11.9), and benzyl alcohol (12.1), pyridine (10.7), and diethylformamide ( 10.6) and dimethylformamide (12.1).

It is also possible to mix another solvent with the solvent. For example, when it is desired to increase the contact time with the solvent, it is possible to add a solvent in which the resin particles do not dissolve, thereby increasing the dissolution time.

Next, the resin particle-adhering inner core obtained as described above is brought into contact with the above-mentioned solvent. The contact can be made using an apparatus as described above. In particular, an apparatus using the nozzle shown in FIGS. 2 and 3 is preferable. When these devices are used, the contact time with the solvent is 10 ⁻⁵ to
It is preferably about 10 seconds, more preferably about 10 seconds.
^{-4 to} 5 seconds. After contact, the particles are dried, preferably by gas transport. The temperature of the carrier gas is preferably about 0 to 150 ° C, more preferably 20 to 150 ° C.
To 100 ° C., and the drying is completed by gas transfer for about 10 to 120 seconds, more preferably 20 seconds or less.

Next, a method for producing a toner by a wet method will be described with reference to FIG.

As the toner core and resin particles, those used in the above-mentioned dry method can be basically used as they are.

First, the resin particles are dispersed in a solvent that does not dissolve the resin particles. Specific examples of the solvent include petroleum solvents such as hexane, heptane, isoper and kerosene, and water. Surfactants such as anionic surfactants, cationic surfactants, nonionic surfactants, polyacrylate derivatives, polymethacrylate derivatives, and anhydrous surfactants to improve the dispersibility of the resin particles. It is also possible to add a polycarboxylic acid salt such as a maleic acid copolymer, a sol-sperse type hyperdispersant, or the like. Also,
The resin particles prepared by the polymerization method can be used as a dispersion by removing the emulsifier, stabilizer, polymerization initiator, and the like from the resin particle dispersion after polymerization by dialysis or the like.

Next, an inner core of the toner is mixed with the resin particle dispersion thus obtained, and an adhesion treatment is performed. At this time, the core of the toner may be in a state of powder or a dispersion liquid dispersed in a solvent. The adhesion treatment can be performed by any of the above-mentioned wet methods, but is preferably performed by a wet milling method, a coupling method, or a heteroaggregation method. In the wet milling method, the ratio of the core of the toner to the particle size of the resin particles is preferably 5 or more. In the coupling agent method,
The particle diameter ratio of the toner core / resin particles is preferably 3 or more. A coupling agent such as silane, titanium, chromium, aluminum, organic phosphorus, or silyl peroxide is added to the toner core or surface treatment is performed. It is necessary to use a functional group having a functional group capable of reacting with the functional group of the ring agent, for example, an amino group, an aldehyde group, an ester group, an epoxy group, a carboxyl group, a chloromethyl group, an acid amide group, a hydroxyl group, a thiol group, or the like. . In the case of the hetero-aggregation method, the particle diameter ratio of the toner inner core / resin particles is preferably 3 or more, and the composition is preferably adjusted so that the zeta potential of the toner inner core 1 and the resin particles 11 has opposite polarity.

The resin particle-adhered core thus obtained can be separated from the dispersion or brought into contact with a solvent as the dispersion.

The resin particle-adhering core thus obtained is then brought into contact with a solvent. The contact is preferably made by dispersing the resin particle-adhering core in a solvent in the case of a resin particle-adhering inner core / solvent system having a low dissolution rate, and then drying the mixture by spray drying or spray drying. In other systems, it is preferable to make contact using, for example, an apparatus using the above-described nozzle. The specific contact time and subsequent drying conditions are basically the same as in the above-mentioned dry method.

Incidentally, the toner having a multilayer structure obtained by the dry or wet method can be used as it is, and if necessary, an external treatment such as a charge control agent or a fluidizing agent can be applied. The toner may be applied to form an electrophotographic toner.

[0047]

The present invention will be described in more detail with reference to the following examples.

Example 1 Styrene / acrylic copolymer 97% by weight Metal-containing azo dye 1% by weight Carbon black 2% by weight The raw materials having the above composition are kneaded with a biaxial extruder, and cooled and roughly pulverized. Next, after being finely pulverized by a jet pulverizer, classification was performed to produce inner core particles having an average particle diameter of 10 μm and a distribution of 5 to 25 μm.

As resin fine particles, polybutyl methacrylate (PBMA), particle size 0.2 μm, glass transition point 8
3 ° C.). The fine particles and the inner core particles are mixed at a composition ratio of 80% by weight of the inner core particles and 20% by weight of the PBMA particles, and the fine particles are converted into the inner core of the toner in a mechanofusion system (manufactured by Hosokawa Micron) at a rotation speed of 1500 rpm for a processing time of 30 minutes. Attached to the surface. Excessive PBMA fine particles not contributing to adhesion of the obtained powder particles were removed by a classifier (removal of excess PBMA particles by a classifier can be omitted by adjusting the charged amount of PBMA particles). Even after the removal, the PBMA particles did not peel off on the surface of the inner core particles, and the fact that the PBMA particles were attached became clear by electron microscopic observation of the surface. In addition, when the cross section was observed by an electron microscope, it was observed that the PBMA particles were embedded in the inner core particle surface in a spherical state.

The inner core of resin particles adhered as described above is brought into contact with acetone as a solvent as described below. The nozzle shown in FIG. 2A is used as a mixing device.

First, the inner core of the resin particles is supplied to a nozzle. The inner core of the resin particles attached to the nozzle is sucked into the nozzle by an ejector effect generated by a carrier gas flowing at high speed in the nozzle. The inner core of the resin particles attached to the high-speed flow of the carrier gas is converted into primary particles and dispersed in the air flow. On the other hand, acetone as a solvent is supplied to the nozzle from a position facing the core of the nozzle where the resin particles adhere. However, acetone is hindered by the high-speed carrier gas, and does not come into contact with the resin particle-adhering core before the resin-particle-adhering core becomes primary particles. Contact with. The inner core of the resin particles adhered to the acetone is conveyed through the nozzle while being dispersed in the carrier gas in the form of primary particles. At this time, the resin particles on the inner core surface where the resin particles adhere are dissolved by acetone, and a PMBA / acetone resin solution layer is formed on the inner core surface. Subsequently, a mixture of the resin particle-adhering core, acetone, and the carrier gas is discharged from the nozzle, and the process proceeds to a drying step. Here, the contact time between the resin particle-adhering inner core and acetone refers to the time from when the three members of the resin particle-adhering inner core, acetone and the carrier gas are supplied to the nozzle to when they are discharged from the nozzle, and in this embodiment. In this case, the time is 0.1 second or less. In the drying device, the P on the inner core surface is
Acetone evaporates from the MBA / acetone resin solution layer, and a PMBA resin coating layer is formed on the inner core surface. further,
The interval between the particles is widened while being discharged from the nozzle to the drying device, and aggregation of the particles is prevented. Thereafter, the particles are sent to a cyclone and collected as toner.

The toner particles thus obtained had no binding between the particles, and each particle was in an independent state. In addition, when the cross section of the particles produced in this example was observed with an electron microscope, a 0.1 micron PBMA resin coating layer was formed on the surface of the inner core particles. After externally adding a fluidity improver to the prepared toner, it was mounted on a one-component non-contact type developing machine and a laser printer having an OPC photoreceptor to form an image. Could be formed.

Example 2 Using the same core particles as in Example 1, the thickness of the coating layer was controlled by changing the particle size of the resin fine particles adhered to the core particles.
As resin fine particles, particle size 0.4 μm (PBMA), particle size 0.8 μm (PMMA), particle size 1.0 μm (PMMA)
Was used. Table 1 shows the conditions for attaching fine particles. Next, these particles were brought into contact with a solvent in the same manner as in Example 1. The obtained particles were observed for the particle surface and the particle cross section by an electron microscope in the same manner as in Example 1, and the film thickness was measured. Table 2 shows the contact conditions and results. By changing the particle diameter of the particles attached to the inner core particle surface in this manner, a coating layer having an arbitrary thickness can be formed.

[0054] * Treatment time: all performed in 30 minutes. * Solvent: acetone

Example 3 In this example, wax was used as the core particles as the main component,
Particles having a magnetic powder and a colorant were used. Other than that, it carried out similarly to Example 1 and prepared the toner core particle. Paraffin wax 30 wt% Polyethylene wax 30 wt% Fe ₃ O ₄ 38 wt% Carbon black 2 wt% The raw materials having the above composition are kneaded with a batch-type kneader, and cooled and roughly pulverized. Next, after being finely pulverized by a jet pulverizer, classification was performed to produce inner core particles having an average particle diameter of 10 μm and a distribution of 5 to 25 μm.

As in Example 1, PBMA was used as fine resin particles, and fine resin particles were adhered to the inner core surface of the toner under the same mixing conditions. However, since the inner core particles are soft, the rotation was performed at 800 rpm and the processing time was 15 minutes. Excessive PBMA fine particles not contributing to adhesion of the obtained particles were removed by a classifier (removal of excess PBMA particles by a classifier can be omitted by adjusting the amount of PBMA particles charged). Even after the removal, the PBMA particles did not peel off on the surface of the inner core particles, and the fact that the PBMA particles were attached became clear by electron microscopic observation of the surface. In addition, when the cross section was observed by an electron microscope, it was observed that the PBMA particles were embedded in the inner core particle surface in a spherical state. The resin particle-adhering inner core obtained as described above was brought into contact with xylene as a solvent using Dispercoat (manufactured by Nisshin Flour Milling Co., Ltd.). Contact time 0.5 seconds, drying temperature 6
Spray dried at 0 ° C. The obtained particles had no binding between the particles as in Example 1, and were aggregates in which each particle was independent. When the cross section of the particles was observed with an electron microscope, 0.1 μm of P
A BMA resin coating layer was formed. After externally adding a fluidity improving agent to the produced toner, an image mounted on a laser printer having a one-component magnetic brush developing machine and an OPC photoreceptor was formed. A clear image could be formed at a temperature as low as ℃.

Example 4 Using the same inner core particles as in Example 3, the film thickness was controlled by changing the particle size of the resin fine particles adhered to the inner core particles. Third
The table shows the conditions for adhering fine particles.

[0058] * Treatment time: all performed in 15 minutes. Next, in the same manner as in Example 2, the inner core of the resin particles was brought into contact with the solvent. However, xylene was used as a solvent.
As a result, the same results as in Table 2 of Example 2 could be obtained. This shows that a coating layer having an arbitrary thickness can be formed by changing the particle diameter of the fine particles adhered to the surface even when relatively soft particles mainly composed of wax are used as the inner core particles.

Example 5 The same inner core particles as in Example 3 were made to adhere to SiO ₂ , and the particles were subjected to spheroidizing treatment by a hot air method. As a method for attaching SiO ₂ , a mechanofusion system (manufactured by Hosokawa Micron) was used. The mixed composition of SiO ₂ was 100% by weight of inner core particles and 5% by weight of SiO ₂ . Next, the above-mentioned processing raw materials were set in a mechanofusion apparatus, and processing was performed at a rotation speed of 800 rpm for 15 minutes. The result was a flowable powder. Next, the inner core particles having the SiO ₂ adhered to the surface were subjected to a spheroidizing treatment. The treatment was performed by spraying the powder into a hot air flow. The processing conditions are shown below. Hot air temperature 200 ° C Hot air flow 100 l / min Powder supply speed 200 g / hr Air supply amount for powder supply 5 l / min When the inner core particles treated by the above method are observed with an electron microscope, they have a shape close to a true sphere. The inner core surface was also very smooth without irregularities. Using the spherical inner core particles, resin fine particles were adhered in the same manner as in Example 3 and then brought into contact with a solvent, whereby a coating layer similar to that of Example 3 could be formed. Further, when an image was formed in the same manner as in Example 3, the same results as in Example 3 were obtained.

Example 6 Binder resin: styrene-n-butyl methacrylate copolymer 53 g Colorant: channel black 4 g Magnetic powder: Fe ₃ O ₄ 40 g Release agent: polypropylene wax 3 g The above were mixed and kneaded by a batch kneader. And finely pulverized into fine particles of 10 to 15 μm by a jet mill to prepare an inner core of the toner. The whole amount of the inner core of the toner was mixed with 500 ml of a methyl methacrylate-butyl methacrylate copolymer (particle diameter: 0.3 μm, 5% aqueous dispersion) as resin particles, and an adhesion treatment was performed by a wet milling method using a ball mill. Subsequently, the resultant was dried with a spray drier to obtain a resin particle-adhered toner. While the resin particle-adhered toner was discharged from the powder supply nozzle, 1000 ml of methyl ethyl ketone as a solvent was sprayed in a mist form from a two-fluid nozzle and dissolved and fixed to prepare a resin-coated toner. Further, 2 g of silicon oxide as a fluidizing agent and 5 g of a metal-containing dye as a charge control agent were externally added, and classified to remove unattached components, thereby producing an electrophotographic toner. This is referred to as toner A.

Example 7 Binder resin: styrene-n-butyl methacrylate copolymer 51 g Colorant: channel black 4 g Magnetic powder: Fe ₃ O ₄ 40 g Release agent: polypropylene wax 3 g Coupling agent: amine silane coupling Agent 2g The above mixture was mixed and kneaded by a batch kneader, and finely pulverized into fine particles of 10 to 15 μm by a jet mill to prepare an inner core of the toner. Methyl methacrylate-butyl methacrylate-methacrylic acid copolymer (particle diameter: 0.3 μm, 5% aqueous dispersion) as resin particles with the total amount of the inner core of the toner 50
Then, the mixture was mixed and stirred at 60 ° C. for 10 hours to perform an adhesion treatment by a coupling reaction. Subsequently, the resultant was dried with a spray drier to obtain a resin particle-adhered toner.
The resin-coated toner was prepared by spraying 1000 ml of methyl ethyl ketone as a solvent in a mist form from a two-fluid nozzle while discharging the resin particle-adhered toner from the powder supply nozzle to dissolve and fix the resin. Further, 2 g of silicon oxide as a fluidizing agent was externally added and subjected to a classification treatment for removing unattached components, thereby producing an electrophotographic toner. This is called toner B.

Example 8 Binder resin: styrene monomer 20 g n-butyl methacrylate monomer 30 g dimethylaminoethyl methacrylate monomer 3 g Colorant: channel black 4 g Magnetic powder: Fe ₃ O ₄ 40 g Release agent: polypropylene wax 3 g Polymerization initiator: 40 g of benzoyl peroxide The above total amount was mixed and dispersed, and 3% of carboxymethylcellulose and 1 liter of an aqueous solution were added. A toner inner core was prepared by a suspension polymerization method, followed by dialysis to obtain a toner inner core aqueous dispersion solution. Resin particle aqueous dispersion methyl methacrylate-butyl methacrylate-methacrylic acid copolymer (particle size 0.3
(2 μm, 2% aqueous dispersion), mixed and stirred for 24 hours to perform an adhesion treatment by a heteroaggregation method. Subsequently, drying and formation of an emulsifier-dissolved film were simultaneously performed by a spray dryer to prepare a resin-coated toner. Further, 2 g of silicon oxide as a fluidizing agent was subjected to an external addition treatment and a classification treatment for removing unattached components, thereby producing an electrophotographic toner. This is referred to as toner C.

Comparative Example 1 Binder resin: styrene-n-butyl methacrylate copolymer 53 g Colorant: channel black 4 g Magnetic powder: Fe ₃ O ₄ 40 g Release agent: polypropylene wax 3 g The above were mixed and kneaded by a batch kneader. And finely pulverized into fine particles of 10 to 15 μm by a jet mill to prepare an inner core of the toner. The total amount of the inner core of the toner was mixed with 25 g of a methyl methacrylate-butyl methacrylate copolymer (particle diameter: 0.3 μm) as resin particles, and an adhesion treatment was performed by a mechanochemical method using a ball mill. Subsequently, 2 g of silicon oxide as a fluidizing agent and 5 g of a metal-containing dye as a charge control agent were externally added, and classified to remove unattached components, thereby producing an electrophotographic toner. This is called toner D
And

Comparative Example 2 Binder resin: 22 g of styrene monomer 31 g of n-butyl methacrylate monomer Colorant: 4 g of channel black Magnetic powder: 40 g of Fe ₃ O ₄ Release agent: 3 g of polypropylene wax Polymerization initiator: 40 mg of benzoyl peroxide The whole amount was mixed and dispersed, and added to a 3% aqueous solution of carboxymethylcellulose-hydroxypropylcellulose as a dispersion stabilizer and a resin solution for capsule coating, and a toner core was prepared by a suspension polymerization method and a spray drying method.
Further, 2 g of silicon oxide was externally added as a fluidizing agent, and a classification treatment was performed to remove unattached components, thereby producing an electrophotographic toner. This is referred to as toner E. Toners A to E
Table 4 shows the results obtained by observing the cross section of the toner for electrophotography using a transmission electron microscope and determining the thickness of the resin coating layer.

[0065] As shown in Table 4, the variation in the thickness of the resin coating layer of the electrophotographic toners A, B, and C according to the examples of the present invention was smaller than that of the electrophotographic toner D according to the comparative example. , A uniform coating layer was formed. In comparison, the toner D had uneven adhesion of the resin particles, and the thickness variation was large. Further, the thickness of the toner E was 0.02 μm or less, which was extremely thin as compared with other toners.

When the toner A to E is used in a one-component magnetic developing device, the developing device is driven for 15 hours without printing, and printing is performed on an image forming body before and after stirring. Table 5 shows the measurement results of the optical reflection density of the non-image forming portion.

[0067] As shown in Table 5, the electrophotographic toners A, B, and C in the examples of the present invention were formed by driving the developing device and stirring for 15 hours as compared with the electrophotographic toners D and E in the comparative example. The variation in the optical reflection density of the image forming portion and the increase in background stain in the non-image forming portion are small, and the durability and stability of the toner are high. On the other hand, in the toners D and E, the optical reflection density is reduced due to white spots where the toner is not adhered to the image forming portion due to the development unevenness due to the toner aggregation, and the toner surface is further agitated for a long time. The optical reflection density of the non-image forming portion increased due to the occurrence of background contamination due to the generation of the peeled material.

[0068]

According to the present invention, it is possible to manufacture microcapsules capable of forming various coating layers with various thicknesses and controlling the thickness of the coating layers uniformly on various inner cores. In particular, a high-performance toner having a multilayer structure can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a preferred apparatus for carrying out a method for producing microcapsules according to the present invention.

FIG. 2 is a diagram of a mixing apparatus for mixing a resin particle-adhering inner core, a solvent, and a gas.

FIG. 3 is a diagram of a mixing device that mixes a resin particle-attached inner core, a solvent, and a gas.

FIG. 4 is a diagram illustrating a toner manufacturing process by a dry method.

FIG. 5 is a diagram showing a toner manufacturing process by a wet method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 powder mixing device 2 powder supply device 3 solvent supply device 4 mixing device 5 gas 6 drying device 7 recovery device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-200269 (JP, A) JP-A-1-180241 (JP, A) JP-A-62-278547 (JP, A) JP-A-1- 257853 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 9/08 311

Claims (12)

(57) [Claims] 1. A method comprising the following steps (a) to (e):
Manufacturing method of microcapsules. (A) A step of preparing an inner core of a microcapsule. (B) a step of uniformly adhering the resin particles to the surface of the inner core of the microcapsule, and using the inner core as the inner core of the resin particles; (C) a step of converting the inner core of the resin particles to primary particles. (D) a step of bringing the inner core of the resin particles adhered in a primary particle state into contact with a solvent capable of dissolving the resin of the resin particles; (E) a step of drying the inner core of the resin particles adhered to the solvent after contacting with the solvent in a state of primary particles, and thereafter recovering the core. 2. The method for producing microcapsules according to claim 1, wherein the attaching of the resin particles to the inner core in the step (b) is performed by a mechanochemical reaction. 3. The method for producing microcapsules according to claim 1, wherein the attaching of the resin particles to the inner core in step (b) is performed in a liquid. 4. The method for producing microcapsules according to claim 1, wherein the primary particle formation in the step (c) is carried out by gas transporting the inner core of the resin particles. 5. The method for producing microcapsules according to claim 1, wherein the primary particles in the step (c) are dispersed by dispersing the inner core of the resin particles in a liquid. 6. The method according to claim 4, wherein the contact between the inner core of the resin particles and the solvent in the step (d) is performed by spraying the solvent into a space where the inner core of the resin particles is present in a primary particle state. Production method of microcapsules. 7. The method for producing microcapsules according to claim 1, wherein the contact between the resin particle-attached inner core and the solvent in the step (d) is performed by dispersing the resin particle-attached inner core in the solvent. 8. The method for producing microcapsules according to claim 6, wherein the drying in the step (e) is carried out by further transporting the inner core of the resin particles adhered after contact with the solvent. 9. The method for producing microcapsules according to claim 7, wherein the drying in the step (e) is performed by spray drying. 10. The method for producing microcapsules according to claim 1, wherein the adhesion of the resin particles to the surface of the inner core in step (b) is one layer. 11. The method for producing a microcapsule according to claim 1, wherein the core of the microcapsule is a core of a toner containing at least a binder component. 12. A microcapsule produced by the method for producing a microcapsule according to any one of claims 1 to 10.