JPH06170214A - Microcapsule, capsule toner and production of microcapsule - Google Patents

Abstract

PURPOSE:To produce a microcapsule with the core sufficiently coated and excellent in mechanical strength, preservation property and flowability, a capsule toner capable of being charged almost irrespective of the environment and a liq.-core microcapsule without the diameter being fluctuated and which is safe and sanitary in high yield without need for a special production device. CONSTITUTION:The microcapsule and capsule toner contain a polymer consisting of a monomer capable of being polymerized by the reaction of the shell material with core material on the surface and an inorg. fine powder, and the polymer is chemically combined with the fine powder. An oleophilic core material is emulsified in an the medium in the presence of a monomer such as isocyante, halide and epoxy compd., a monomer such as polyamines and polyols and an inorg. fine powder having active hydrogen on the surface, and the monomers are polymerized on the surface of the oleophilic core material to produce the microcapsule.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a capsule toner used for developing an electric or magnetic latent image in an electrophotographic method, an electrostatic recording method or a magnetic recording method, and a capsule toner. Possible microcapsules and a method for producing the same.

[0002]

2. Description of the Related Art Various proposals have heretofore been made for microcapsules comprising a core substance and a capsule shell covering the core substance. By the way, in order to apply the microcapsule to the electrophotographic toner, it is necessary to impart chargeability to the capsule shell in order to visualize the electrostatic latent image. Therefore, a method of obtaining a toner by spray-drying a polymer containing a charge control agent on a toner base or coating the toner base under heat or pressure is disclosed in JP-A-57-2025.
47, JP-A-63-27853 and JP-A-63-27854.

However, the spray dry method has a drawback in that a plurality of toner bases are covered with a coating layer and the toner particle size becomes large. Therefore, even if the sieving operation is performed after coating, the yield of toner having a predetermined particle diameter is low. Furthermore, since a large amount of organic solvent is used, there are safety and health problems. The method of coating the toner base material by heat fusion also has a drawback in that the toner particles are adhered and aggregated to increase the toner particle size. Further, the method of fusing the coating polymer on the toner base under pressure can be applied when the toner base particles to be heat-fixed are hard, but when this method is applied to the liquid core capsule toner, the capsule is It has the drawback of being destroyed.

Further, a method of preparing a toner by forming a coating layer composed of a coloring agent or magnetic particles and a conductive agent and a binder resin on the surface of toner core particles by using a jet mill is disclosed in JP-A-60- No. 173,552. Japanese Patent Application Laid-Open No. 63-49766 discloses a method in which a toner base particle and a thermoplastic resin are mixed with each other by applying a strain force and then coated. These methods are applicable when the toner base particles are hard as in the case of aiming at the above-mentioned heat fixing, but this method is applicable to the capsule toner having a liquid core for the purpose of pressure fixing. The application still has the drawback that the capsule is destroyed.

On the other hand, toner core particles formed by polymerization are dispersed in a latex aqueous solution, a water-soluble inorganic salt is added, and fine particles are allowed to settle on the surface of the toner core particles to form a coating layer to prepare a toner. The method is disclosed in JP-A-57-45.
No. 558, gazette. But this method
Since fine particles adhere to the core material to form a coating layer,
The adhesion between the coating layer and the core material is poor, and the coverage of the core material is insufficient. In addition, there is a drawback in that the charge greatly depends on the environment due to the influence of the surfactant and the inorganic salt remaining on the toner, and the charge amount is reduced particularly in a high temperature and high humidity environment.

Further, a capsule toner in which a hydrophilic inorganic powder is mixed in a capsule shell is described in JP-A-59-79257, and a capsule toner in which a lipophilically treated inorganic powder is mixed in the capsule shell is produced. The method is disclosed in JP-A-2-8105.
No. 2 publication. However, in the former,
There is no chemical bond between the lipophilic capsule shell polymer and the hydrophilic inorganic powder, they are merely mixed, and it is expected from the combination of lipophilicity and hydrophilicity which are contradictory properties. As described above, the adhesive force and the adhesiveness do not sufficiently act between the shell polymer and the inorganic powder. Also in the latter case, there is no chemical bond between the capsule shell and the inorganic powder, and they are simply mixed, which is the same as the former case. Therefore, the mechanical strength of the shell is not sufficient and the sealing property of the core material is poor. As a result, there are drawbacks that storage stability is poor and fluidity deteriorates over time. This is a problem especially when a liquid material is used as the core material.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and its object is to provide sufficient core material coverage and mechanical strength,
It is intended to provide a microcapsule excellent in storage stability and fluidity and a capsule toner having little environmental dependence of charging. Another purpose is the production of microcapsules without fluctuations in capsule particle size, high yield, less safety and health problems, suitable for the production of liquid-core microcapsules, and requiring no special production equipment. To provide a method.

[0008]

As a result of intensive studies, the present inventor has found that the capsule shell is made of a mixture of an inorganic fine powder and a polymer, and each component of the mixture is chemically bonded. By realizing the capsule, it has been found that the above object can be achieved, and the present invention has been completed.

That is, the first feature of the present invention is that a core substance and a shell substance that covers the core substance are present, and the shell substance is composed of at least two kinds of monomers which can react with each other and polymerize on the surface of the core substance. The microcapsules contain a coalesce and an inorganic fine powder, and the polymer and the inorganic fine powder are chemically bonded. A second feature of the present invention is that the shell substance covering the core substance contains a polymer composed of at least two kinds of monomers capable of reacting with each other on the surface of the core substance to polymerize, and an inorganic fine powder, and An encapsulated toner comprising microcapsules in which a polymer and an inorganic fine powder are chemically bonded. A third feature of the present invention is to add a lipophilic core substance to an aqueous medium in the presence of at least two kinds of monomers capable of reacting with each other on the surface of the core substance and polymerizing, and an inorganic fine powder having active hydrogen on the surface. It is a method for producing microcapsules in which the above-mentioned monomer is polymerized on the surface of the lipophilic core substance.

The present invention will be described in detail below. The core substance forming the microcapsules in the present invention is not particularly limited, and various active substances can be used as the core substance component depending on the application as long as they are poorly water-soluble or oil-soluble. When microcapsules are used as capsule toners, a core substance mainly composed of a component having a pressure fixing property is used for the purpose of pressure fixing, and a main component having a heat fixing property is used for the purpose of heat fixing. And a core substance is used. In particular, for the purpose of pressure fixing, as the core substance, those mainly composed of a binder resin and a high boiling point solvent and a colorant which dissolve or swell it, or those mainly composed of a soft solid substance and a colorant Is preferably used. The colorant may optionally be replaced by magnetic powder. As the core substance, an additive such as silicone oil may be added if necessary for the purpose of improving the fixing property. It is also possible to add an organic solvent mainly containing insoluble saturated aliphatic hydrocarbon to the binder resin. When the purpose is pressure fixing and the purpose is heat fixing, it is desirable to change the type or composition ratio of the fixing component.

As the binder resin, a known fixing resin can be used. Specifically, acrylic acid ester polymers such as polymethyl acrylate, polyethyl acrylate, butyl polyacrylate, 2-ethylhexyl polyacrylate, lauryl polyacrylate, and stearyl polyacrylate, polymethyl methacrylate, polymethyl methacrylate. Butyl methacrylate, poly (hexyl methacrylate), 2-ethylhexyl polymethacrylate, poly (lauryl methacrylate), poly (methacrylic acid stearyl) and other methacrylate ester polymers, polyvinyl acetate, vinyl polypropionate, polyvinyl butyrate and other vinyl ester polymers , Olefin polymers such as polyethylene and polypropylene, and copolymers thereof, copolymers of styrene monomers and acrylic acid esters or methacrylic acid esters, styrene-butadiene copolymers, styrene-isoprene copolymers , Styrene - styrene copolymer and maleic acid copolymers, further polyvinyl ether, polyvinyl ketone,
Examples thereof include polyester, polyamide, polyurethane, rubber, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin and phenol resin.
These binder resins can be used alone or in combination. The soft solid substance may be of any type as long as it has flexibility and fixability at room temperature, but it is a polymer having a glass transition point Tg in the range of −60 to 5 ° C. or a polymer thereof and others. A mixture with the polymer of is preferably used.

The high boiling point solvent which dissolves or swells the binder resin has a boiling point of 140 ° C. or higher, preferably 16
An oily solvent at 0 ° C or higher can be used. For example, M
odern Plastics Encycloped
ia (1975-1976) "Plasticize"
It may be selected from the solvents described in “rs”. Further, as the core substance of the pressure fixing capsule toner, for example, JP-A-58-145964 and JP-A-63-163 may be used.
It may be selected from the high boiling point solvents disclosed in Japanese Patent No. 373, etc. Specifically, phthalic acid esters (diethyl phthalate, dibutyl phthalate, etc.), aliphatic dibasic acid esters (diethyl malonate, dimethyl succinate, dioctyl adipate, etc.), phosphoric acid esters (tricresyl phosphate, triglyceride) Silyl phosphate, etc., citric acid esters (O-acetyltriethyl citrate, etc.), benzoic acid esters (butyl benzoate, hexyl benzoate, etc.), higher fatty acid esters (hexadecyl myristate, etc.), alkyl naphthalenes (methyl naphthalene, etc.) , Dimethylnaphthalene, monoisopropylnaphthalene, diisopropylnaphthalene, etc.), alkyl diphenyl ethers (o-, m-, p
-Methyldiphenyl ether, etc.), higher fatty acid amides (N, N-dimethyllaurinamide, etc.), aromatic sulfonic acid amides (N-butylbenzenesulfonamide, etc.), trimellitic acid esters (trioctyl trimellitate, etc.) , Diarylalkanes (diarylmethane such as xylylphenylmethane, 1-phenyl-1-tolylethane, 1-xylyl-1-phenylethane, 1-
Examples thereof include diarylethane such as ethylphenyl-1-phenylethane) and chlorinated paraffins.

Further, when a high boiling point solvent is used in combination with an aliphatic saturated hydrocarbon which is insoluble in the binder resin or an organic solvent containing this as a main component, not only the fixability is improved but also the binder resin is incorporated into the core substance. It can be well dispersed and held. Furthermore, when a polymer having a long-chain alkyl group such as lauryl methacrylate homopolymer or copolymer is used as the binder resin, it is preferable to use an aliphatic saturated hydrocarbon together as a solvent for the binder resin. It is desirable because it has little effect on Such an aliphatic saturated hydrocarbon has a boiling point of 100 to
It is preferably 250 ° C., and examples thereof include Isopar G, Isopar H, and Isopar L manufactured by Exxon Chemical Co., Ltd.

Examples of the colorant include inorganic pigments such as carbon black, red iron oxide, navy blue, and titanium oxide, azo pigments such as fast yellow, disazo yellow, pyrazolone red, chelate red, brilliant carmine, and para brown, copper phthalocyanine, metal-free phthalocyanine. And a condensed polycyclic pigment such as flavantron yellow, dibromoanthrone orange, perylene red, quinacridone red, and dioxazine violet. Further, disperse dyes, oil-soluble dyes and the like can also be used. Furthermore, in the case of a magnetic one-component toner or the like, all or part of the black colorant can be replaced with magnetic powder. As the magnetic powder, magnetite, ferrite, a simple metal such as cobalt, iron, nickel, or an alloy thereof can be used. In addition, these magnetic powders may be surface-treated with a coupling agent such as a silane coupling agent or a titanate coupling agent or an oil-soluble surfactant, or the surface may be coated with an acrylic resin, a styrene resin, an epoxy resin or the like. It may be a magnetic powder.

As the first monomer forming the shell material in the microcapsule, an isocyanate compound, an acid halide, an epoxy compound or the like is used. In particular, when the microcapsules are applied to an electrophotographic toner, at least an isocyanate compound is preferably used as a shell-forming monomer component from the viewpoint of electric resistance. Specific examples of the isocyanate compound include m-phenylene diisocyanate, tolylene diisocyanate, diphenylmethane-
4,4'-diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, o-, m-, p
-Diisocyanate compounds such as xylylene diisocyanate, naphthalene diisocyanate, and 1,6-hexamethylene diisocyanate, and polyisocyanate known as so-called burette type, adduct type, isocyanurate type, and the like. To be Specific examples of acid halides include dibasic acid halides such as succinoyl chloride, adipoyl chloride, fumaroyl chloride, phthaloyl chloride, terephthaloyl chloride, and 1,4-cyclohexanedicarbonyl chloride. . Specific examples of epoxy compounds include epoxy compounds known as bisphenol A type, resorcin type, bisphenol F type, tetraphenylmethane type, novolac type, polyalcohol type, polyglycol type, glycerin triether type, and the like. . These first monomers can be used alone or in combination.

The second monomer which also reacts with the first monomer to form the shell material of the microcapsule is ethylenediamine, tetramethylenediamine, hexamethylenediamine, phenylenediamine, diethylenetriamine, triethylenetetramine. , Tetraethylenepentamine, diethylaminopropylamine, piperazine, 2
-Polyamines such as piperazine compounds such as methylpiperazine and 2,5-dimethylpiperazine, ethylene glycol, 1,4-butanediol, catechol, resorcinol, hydroquinone, o-dihydroxymethylbenzene, 4,4'-dihydroxydiphenylmethane, 2 ，
In addition to polyols such as 2-bis (4-hydroxyphenyl) propane, water can be used. These second monomers can be used alone or in combination.

The first monomer and the second monomer react with each other on the surface of the core substance to form a polymer. For example, as the first monomer, an isocyanate compound is used. Is reacted with a second monomer, polyamine, water or a polyol, to form polyurea or polyurethane. When an acid halide is used to react with a polyamine, a polyamide is produced, and when an epoxy compound is used to react with a polyamine or a polyol, the epoxy compound is polymerized through these second monomers. Furthermore, when the isocyanate compound is reacted with the polyamine and the polyol at the same time, a polymer containing a urea bond and a urethane bond in the molecular chain is produced.

The inorganic fine powder used in the present invention has an average particle size of 0.005 to 5 μm, preferably 0.0
It means an inorganic fine powder having a size of 2-1 μm and having a functional group having active hydrogen on the surface thereof, which reacts with an isocyanate compound, an acid halide or an epoxy compound and is incorporated into a capsule shell matrix. As the functional group having active hydrogen, a carboxyl group, an amino group,
Examples thereof include a hydroxyl group, a mercapto group and an amidino group. Among them, as the hydroxyl group, the hydroxyl group which the surface of a normal metal oxide fine powder has can be used. Specific examples of these inorganic substances include silicon oxide, titanium oxide, aluminum oxide (alumina), zinc sulfide, lead titanate,
Examples thereof include zirconium oxide, white lead, zinc white, red lead, cadmium red, and cadmium yellow.

The functional group having active hydrogen may be, in addition to the hydroxyl group present on the surface during the synthesis of the inorganic fine powder, a hydroxyl group converted into another functional group by utilizing a chemical reaction. For example, the inorganic fine powder is treated with a surface treatment agent such as a silane coupling agent having a functional group containing active hydrogen substituted therein, a titanate coupling agent, an aluminum coupling agent, a zircoaluminate coupling agent, and the like. A chemically bonded functional group can be used. The specific treatment method with the coupling agent is
It is described in detail in "Optimum Utilization Technology of Coupling Agent" (National Institute of Science and Technology, published February 25, 1988). From the viewpoint that the chargeability and reactivity can be controlled, the inorganic fine powder is preferably treated with a coupling agent,
An amino group is particularly preferable as the functional group having active hydrogen. The above inorganic fine powder having active hydrogen on the surface can be used alone or in combination.

The method for producing the microcapsules of the present invention comprises:
There are roughly two methods, an interfacial polymerization method and an internal in-situ polymerization method. The first interfacial polymerization method is to emulsify a lipophilic mixture containing at least a first monomer and a capsule core substance in an aqueous medium, and then add an inorganic fine powder having active hydrogen on the surface to an emulsion. Then, the first monomer present in the lipophilic droplets and the second monomer present in the aqueous medium react at the interface of the lipophilic droplets to form a capsule shell. The method for producing microcapsules by this interfacial polymerization method is, for example, Japanese Patent Publication No. 38-19574, Japanese Patent Publication No. 42-446, Japanese Patent Publication No. 2-31381, Japanese Patent Publication No. 58-66948, and Japanese Patent Publication No. 59948. -14
No. 8066 and Japanese Patent Laid-Open No. 59-162562.

The second internal in-situ polymerization method is to emulsify a lipophilic mixture containing at least the first monomer and the capsule core substance in the presence of an inorganic fine powder having active hydrogen on the surface, This is a method in which the first monomer and the second monomer present in the lipophilic droplets react at the interface of the lipophilic droplets to form a capsule shell. A method for producing microcapsules by this internal in-situ polymerization method is described in, for example, Japanese Patent Publication No.
It is disclosed in Japanese Patent Publication No. 9-45133 and Japanese Patent Publication No. 50-22507. In these methods, the second monomer may be charged inside the lipophilic droplets together with the capsule core substance, or may be charged in the aqueous medium outside the lipophilic droplets.

In both of the above two methods, at least one kind of isocyanate compound, acid halide, epoxy compound, etc., which is the first capsule shell forming monomer, and at least one kind of water, polyamine, polyol, etc. And a chemical reaction occurs with the inorganic fine powder having active hydrogen,
The inorganic fine powder is incorporated into at least one polymer selected from polyurea, polyurethane, polyamide, epoxy polymer and the like, and forms a capsule shell in a state of being chemically bonded to the polymer. Alternatively, the core substance may be charged in the form of a binder resin-forming monomer, and after forming a capsule shell by interfacial polymerization, the monomer may be polymerized to form a binder resin for encapsulation. Further, the colorant or magnetic powder charged as one component of the core substance is usually present in the shell substance after capsule formation, but may be present at the interface between the core substance and the shell substance.

In the production of microcapsules, when the lipophilic core substance has a high viscosity, it is added to a low boiling point solvent in advance and the core substance component is suspended in an aqueous medium to form the shell substance or to form the shell substance. After forming the substance, it is preferable to drive the solvent out of the system to form the core substance. Of course, the low boiling point solvent may be removed before capsule formation. As the low boiling point solvent, a solvent having a boiling point of 160 ° C. or lower is preferable, and specifically, methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, carbon disulfide,
Methyl acetate, ethyl acetate, methyl alcohol, ethyl alcohol, ethyl ether, tetrahydrofuran, dioxane, n-pentane, n-hexane, benzene, toluene, xylene, petroleum ether, acetone, methyl ethyl ketone, cyclohexanone, dimethylformamide and the like can be mentioned. . These solvents can be used alone or as a mixture.

For the purpose of preventing offset when fixing the capsule toner, wax or silicone oil may be contained as one component of the core substance. Examples of waxes include animal waxes such as beeswax and lanolin, plant waxes such as candelilla wax, carnauba wax, wood wax, mineral waxes such as montan wax, petroleum waxes such as paraffin wax and microcrystalline wax. , Montan wax derivative,
Modified wax such as paraffin wax derivative, microcrystalline wax derivative, hydrogenated wax such as castor wax, polyolefin wax such as low molecular weight polyethylene, low molecular weight polypropylene and their derivatives, synthetic wax such as distearyl ketone, caprylic amide, pelargone Acid amides, capric acid amides, lauric acid amides, myristic acid amides, stearic acid amides, oleic acid amides, fatty acid amide waxes, and the like can be used. These waxes can be used alone or as a mixture.

The capsule toner of the present invention comprises a metal, a metal oxide such as titanium oxide and alumina, a metal salt, an inorganic substance such as silica and ceramic in order to further improve the chargeability, the fluidity of the powder, the lubricity and the like. Resins such as polymethylmethacrylate and external additives such as fatty acid metal salts may be added. Further, it may be a one-component capsule toner that does not use a carrier, or a two-component capsule toner that uses a carrier. When a carrier is used, it is not particularly limited as long as it is a known carrier, and an iron powder type carrier, a ferrite type carrier, a surface-coated ferrite carrier, a magnetic powder dispersion type carrier and the like can be used.

The capsule toner of the present invention may be used not only for pressure fixing but also for fixing by applying heat and pressure at the same time.
Further, in an image recording apparatus provided with a pressing member that comes into contact with the image carrier via the recording paper or a pressing member having a heating means inside, it may be used for an image recording method of transferring and fixing toner at the same time. It is also effective when used for heat fixing. Further, it can be used not only for recording on paper, but also for a second original drawing, overhead projector paper, and the like.

[0027]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. In addition, the following "part" means a weight part. Example 1 (Preparation of silicon oxide fine powder having amino groups on the surface) γ-aminopropyltriethoxysilane (A-110) was added to a mixed solution of 180 parts of ethanol and 20 parts of ion-exchanged water.
0; manufactured by Nippon Unicar Co., Ltd.) 2 parts was added. Then, 20 parts of silicon oxide fine powder having a hydroxyl group on the surface and an average particle diameter of 0.016 μm (Aerosil 130; manufactured by Nippon Aerosil Co., Ltd.) was added and stirred at room temperature for 1 hour. Then, it was filtered under reduced pressure and dried by heating at 110 ° C. under a nitrogen gas atmosphere. This was put into a high-speed rotary mixer and dispersed at 10,000 rpm for 1 minute to obtain silicon oxide fine powder having an amino group on the surface.

(Production of microcapsules) Lauryl methacrylate was added to a mixed solution of 20 g of saturated aliphatic hydrocarbon (Isopar H; manufactured by Exxon Chemical Co.) and 40 g of ethyl acetate.
60 g of styrene copolymer (Mw: 9 × 10 ⁴ ) was added and dissolved. Next, 10 g of an isocyanate compound (Sumijour L; manufactured by Sumitomo Bayer Urethane Co., Ltd.), which is a first capsule shell-forming monomer, and 20 g of ethyl acetate were added and thoroughly mixed (this liquid is referred to as liquid A). On the other hand, 400 g of ion-exchanged water has hydroxypropylmethylcellulose (Metroses 60SH50; manufactured by Shin-Etsu Chemical Co., Ltd.)
After 10 g was dissolved, 10 g of the silicon oxide fine powder having an amino group on the surface was mixed therein and cooled to 5 ° C. This liquid was stirred with an emulsifying machine (auto homomixer; manufactured by Tokushu Kika Co., Ltd.), and the liquid A was slowly added thereto to emulsify. In this way, an O / W emulsion in which the average particle size of the oil droplet particles in the emulsion was about 12 μm was obtained. Next, the emulsifier was replaced with a stirrer (three-one motor; manufactured by Shinto Scientific Co., Ltd.) equipped with a propeller-type stirrer blade, and the emulsion was changed to 40
Stirred at 0 rpm. After 10 minutes, 100 g of a 5% aqueous solution of diethylenetriamine as the second capsule shell forming monomer was added dropwise to this liquid. After the dropping was completed, the encapsulation reaction was carried out for 3 hours while removing ethyl acetate at 60 ° C. After completion of the reaction, the reaction mixture was poured into 2 liters of ion-exchanged water, sufficiently stirred, and then allowed to stand. After the capsule particles settle,
The supernatant liquid was removed. This operation was repeated 7 times to wash the capsule particles. In this way, microcapsules having capsule shells that were a mixture of silicon oxide fine powder and polyurea chemically bonded were produced.

(Evaluation of Microcapsule Performance) The obtained capsule suspension was put into a stainless steel vat and dried at 60 ° C. for 10 hours with a dryer (made by Yamato Scientific Co., Ltd.).
It was sieved with a sieve having an opening of 80 μm. When the oil component in the microcapsules obtained by pulverizing in this way was measured by thermogravimetric analysis, it was 18%.
Next, after heat-treating the microcapsules at 100 ° C. for 10 hours, the oil component was measured in the same manner to find that
Met. Also, when the fluidity was evaluated by the degree of aggregation, it was 30.
%, And had good fluidity. As mentioned above,
The microcapsules of the present invention were excellent in retention and fluidity of the capsule core substance.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the silicon oxide fine powder was not used to obtain powdered and sieved microcapsules. When the oil content of the obtained microcapsules was measured by thermogravimetric analysis, it was 14%. Next, after heat-treating the microcapsules at 100 ° C. for 10 hours, the oil component was similarly measured and found to be 10%. Moreover, when the fluidity was evaluated by the degree of aggregation, it was 60%.
And the liquidity was poor. As can be seen from these results, the microcapsules containing no inorganic fine powder were inferior in retention of the capsule core substance and poor in fluidity.

Example 2 (Preparation of titanium oxide fine powder having amino groups on the surface) 2 parts of isopropyl tri (N-aminoethylaminoethyl) titanate (KR-44; manufactured by Ajinomoto Co.) was added to 100 parts of toluene. . Next, 50 parts of titanium oxide fine powder having a hydroxyl group on the surface and an average particle size of 0.021 μm (Aerosil P-25; manufactured by Nippon Aerosil Co., Ltd.) was added, and the mixture was stirred at room temperature for 1 hour. Then, it was filtered under reduced pressure and dried by heating at 130 ° C. in a nitrogen gas atmosphere. This was put into a high-speed rotary mixer and dispersed at 10,000 rpm for 1 minute to obtain titanium oxide fine powder having an amino group on the surface.

(Production of Capsule Toner) A mixed solution of 20 g of an aliphatic saturated hydrocarbon (Isopar H) and 40 g of ethyl acetate was added to polylauryl methacrylate (Mw: 5 × 1).
0 ⁴ ) 60 g was added and dissolved. To this solution, 70 g of magnetic powder whose surface was hydrophobized with a titanate coupling agent (TTS; manufactured by Ajinomoto Co., Inc.) was added and dispersed by a ball mill for 24 hours. Then, 20 g of an isocyanate compound (Sumijour L) and 24 g of ethyl acetate were added and mixed sufficiently (this liquid is referred to as liquid B). On the other hand, after dissolving 10 g of hydroxypropylmethyl cellulose (Metroze 60SH50) in 200 g of ion-exchanged water, 10 g of the titanium oxide fine powder having an amino group on the surface was mixed therein and cooled to 5 ° C. This liquid was stirred with an emulsifying machine (auto homomixer), and the liquid B was slowly charged into this to emulsify. In this way, an O / W emulsion in which the average particle size of the oil droplet particles in the emulsion was about 12 μm was obtained. Thereafter, the same treatment as in Example 1 was performed to obtain a capsule toner in which the capsule shell was a mixture of titanium oxide fine powder and polyurea chemically bonded.

(Evaluation of Capsule Toner Performance) The obtained capsule suspension was put into a stainless steel vat and dried at 60 ° C. for 10 hours with a dryer (Yamato Scientific Co., Ltd.).
It was sieved with a sieve having an opening of 80 μm. When the oil content in the capsule of the capsule toner obtained by powderizing in this manner was measured by thermogravimetric analysis, it was 14%. Next, this capsule toner was heat-treated at 100 ° C. for 10 hours, and then the oil component was similarly measured and found to be 13%. As described above, the capsule toner of the present invention was excellent in the retention of the capsule core substance.

Comparative Example 2 The same treatment as in Example 2 was carried out except that the titanium oxide fine powder was surface-treated with an alkyl group-containing titanate coupling agent having no functional group (KR-TTS; manufactured by Ajinomoto Co., Inc.). Then, a powdered and sieved capsule toner was obtained. When the oil content in the capsule of the obtained capsule toner was measured by thermogravimetric analysis, it was 10%. Next, after heat treating this capsule toner at 100 ° C. for 10 hours,
Similarly, the oil component was measured and found to be 8%. As can be seen from these results, the capsule toner produced by surface-treating the titanium oxide fine powder with the alkyl group-containing titanate coupling agent having no functional group was inferior in the retention of the capsule core substance.

Example 3 The same procedure as in Example 2 was carried out without surface-treating the titanium oxide fine powder in Example 2 to obtain a powdered and sieved capsule toner. When the oil content of the obtained capsule toner was measured by thermogravimetric analysis, it was 13%. Next, 10
After heat treatment at 0 ° C. for 10 hours, the oil component was similarly measured and found to be 12%. As described above, the capsule toner of the present invention was excellent in the retention of the capsule core substance.

Comparative Example 3 The same procedure as in Example 3 was carried out except that fine titanium oxide powder was not used, to obtain a powdered and sieved capsule toner. 3 g of the obtained capsule toner and iron powder carrier 10
When 0 g was mixed in an environment of a temperature of 20 ° C. and a humidity of 50%, and the charge amount of the capsule toner was measured by the blow-off method, it was +1 μC / g, and it was hardly charged. Further, when the fluidity was evaluated by the cohesion degree in the same manner as in Example 3, it was 60%, and the fluidity was poor.

Example 4 (Preparation of alumina fine powder having amino groups on the surface) Isopropyltri (N-aminoethylaminoethyl) titanate (KR-44) 2 in 100 parts of methyl ethyl ketone
Parts were added. Next, 50 parts of an alumina fine powder having a hydroxyl group on the surface and an average particle diameter of 0.02 μm (Aerosil C; manufactured by Nippon Aerosil Co., Ltd.) was added and stirred at room temperature for 1 hour. After that, vacuum filtration is performed at 130 ° C. under a nitrogen gas atmosphere.
It was dried by heating. Put this in a high speed rotating mixer and
It was dispersed at 0000 rpm for 1 minute to obtain an alumina fine powder having an amino group on the surface.

(Production of Capsule Toner) A mixed solution of 30 g of saturated aliphatic hydrocarbon (Isopar H) and 40 g of ethyl acetate was added to polylauryl methacrylate (Mw: 5 × 1).
0 ⁴ ) 60 g was added and dissolved. To this solution, 70 g of magnetic powder whose surface was hydrophobized with a titanate coupling agent (TTS) was added and dispersed by a ball mill for 24 hours. Then, an isocyanate compound (Takenate D1
60N; manufactured by Takeda Pharmaceutical Co., Ltd.), 10 g of an epoxy compound (Epototo YD-8125; manufactured by Toto Kasei Co., Ltd.) and 24 g of ethyl acetate were added and mixed sufficiently (this liquid was C
As a liquid). On the other hand, 200 g of ion-exchanged water is used for hydroxypropylmethyl cellulose (Metroses 60SH50)
After dissolving 10 g, the mixture was cooled to 5 ° C. This liquid was stirred with an emulsifying machine (auto homomixer), and the liquid C was slowly added to this to emulsify. In this way, an O / W emulsion in which the average particle size of the oil droplet particles in the emulsion was about 12 μm was obtained.

Next, the emulsifier was changed to a stirrer (three one motor), the emulsion was stirred at 400 rpm, 10 g of the alumina fine powder having amino groups on the surface was dispersed in 40 g of ion-exchanged water, and sodium hydroxide was added. The pH-adjusted dispersion was poured into the emulsion. After 5 minutes, 100 g of a 5% aqueous solution of diethylenetriamine was added to this liquid.
Was added dropwise over 10 minutes. After the dropping was completed, the encapsulation reaction was carried out for 3 hours while removing ethyl acetate at 60 ° C. After completion of the reaction, the reaction mixture was poured into 2 liters of ion-exchanged water, sufficiently stirred, and then allowed to stand. After the capsule particles had settled, the supernatant was removed. This operation was repeated 7 times to wash the capsule particles. In this way, a capsule toner was obtained in which the capsule shell was a mixture of alumina fine powder and an epoxyurea polymer chemically bonded.

(Evaluation of Capsule Toner Performance) The obtained capsule suspension was put into a stainless steel vat and dried at 60 ° C. for 10 hours with a dryer (made by Yamato Scientific Co., Ltd.).
It was sieved with a sieve having an opening of 80 μm. In this way, 3 g of the powdered capsule toner and the iron powder carrier 10 were obtained.
0 g was mixed in an environment of a temperature of 20 ° C. and a humidity of 50%, and the charge amount of the capsule toner was measured by the blow-off method. As a result, it was +12 μC / g, which was a good positive charge property.
Further, as in Example 1, the fluidity was evaluated by the cohesion degree, and it was 35%, indicating that the fluidity was good.

[0041]

INDUSTRIAL APPLICABILITY The microcapsule and the capsule toner of the present invention are excellent in storage stability and fluidity, and particularly when applied to the capsule toner, not only can easily and good chargeability be obtained, but also electrostatic charge can be obtained. Also has little environmental dependence.
Further, according to the method for producing a microcapsule and a capsule toner of the present invention, the encapsulation step and the charge control ability imparting step can be performed simultaneously. Moreover, the coating property of the core substance is sufficient, there are few problems in terms of safety and hygiene, it is also suitable for the production of liquid-core microcapsules, and no special production apparatus is required.

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Claims (8)

[Claims] 1. An inorganic fine powder comprising a core substance and a shell substance covering the core substance, the polymer comprising at least two kinds of monomers capable of reacting with each other on the surface of the core substance and polymerizing. A microcapsule characterized in that the polymer and the inorganic fine powder are chemically bonded. 2. A polymer composed of at least two kinds of monomers capable of reacting with each other and polymerizing on the surface of the core substance is polyurea, polyurethane, polyamide or epoxy polymer alone or two or more kinds of these polymers. Claim 1
The described microcapsules. 3. The shell material covering the core material contains a polymer composed of at least two kinds of monomers capable of reacting with each other on the surface of the core material to polymerize, and an inorganic fine powder, and the polymer and the inorganic material. An encapsulated toner comprising microcapsules chemically bonded to fine powder. 4. The polymer composed of at least two kinds of monomers capable of reacting with each other and polymerizing on the surface of the core substance is polyurea, polyurethane, polyamide or epoxy polymer alone or two or more kinds of these polymers. Claim 3
The capsule toner described. 5. A lipophilic core substance is emulsified in an aqueous medium in the presence of at least two kinds of monomers capable of reacting with each other and polymerizing on the surface of the core substance and an inorganic fine powder having active hydrogen on the surface. Then, a method for producing microcapsules, characterized by polymerizing the above monomer on the surface of the lipophilic core substance. 6. The method for producing microcapsules according to claim 5, wherein at least one of the monomers is present in the lipophilic core substance and the other monomer is present in the aqueous medium. 7. The method for producing microcapsules according to claim 5, wherein all the monomers are present in the lipophilic core substance. 8. The method for producing microcapsules according to claim 5, wherein the lipophilic core substance contains at least a binder resin and a high-boiling solvent that dissolves or swells the binder resin.