JP2617466B2 - Powder toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a powder toner used in a method of converting an electrostatic latent image into a visible image, such as electrophotography and ion flow recording. .

More specifically, the present invention relates to a capsule toner which is fixed on a paper or the like by a pressure which forms a shell by an interfacial polymerization method.

(Prior art) As a powder toner for converting an electrostatic latent image into a visible image, a dye, a pigment, a magnetic powder, and the like are dispersed in a resin for a toner by melting and kneading, and after cooling, this is mechanically pulverized. Generally, a method of classifying the particles is used.

However, it has been pointed out that the toner obtained by this method has an irregular shape, it is difficult to obtain a uniform charge, and the flowability is poor.

Further, in the production, the consumption of electric energy required for melt-kneading and pulverization is enormous, and it has been studied to obtain a powder toner by a method other than the so-called pulverization method.

Spray drying, emulsion polymerization, suspension polymerization, interfacial polymerization, and the like are known as methods for producing powder toner other than the so-called pulverization method, which is produced by the above-described melt-kneading and subsequent pulverization.

However, in the method of manufacturing by the spray drying method, a spherical toner is generated, so that a uniform charge can be obtained and the fluidity becomes good. However, explosion-proof measures for the spray drying method and solvent recovery are required. The disadvantages are that the heat energy required for drying is enormous, the solvent remains in the toner even after drying, and it is difficult to remove the toner. In addition, when sufficient physical properties of the toner are imparted, Due to material limitations, it is difficult to obtain toner with sufficient characteristics by this method alone.

In addition, various methods for forming spherical toner particles in water by emulsion polymerization, suspension polymerization, interfacial polymerization, etc. have been studied. However, dispersing agents and stabilizers used in the production of toner particles in water have been studied. Is difficult to remove because it remains on the surface of the toner particles, which absorbs moisture in the air and lowers the electrical resistance of the toner, making it difficult to copy plain paper and making the charge on the toner surface non-uniform. It is pointed out. In addition, it has been pointed out that spherical particles have poor cleaning properties on the photoreceptor surface.

Also, with the speeding up of the electrophotographic system, or in unmanned machines such as facsimile machines, the system of fixing by heating and the system of fixing the toner by crushing the toner with a pressure roll have been reviewed. This method does not require machine warm-up, and
It requires less energy for fixing and can respond to higher speeds.

However, the fixing method using the pressure roll has a drawback that the toner fixing property is poor, the printing portion of the toner is weak to bend, the gloss is remarkable, and the toner is easily peeled off as compared with the fixing method using the heating roll. . Also,
Conventional pressure rolls crush the toner with high pressure, which makes the machine heavy and / or
It has been pointed out that the paper which has passed through the pressure roll has a glossy feeling and the strength of the paper is reduced.

As a toner for solving such a drawback, there is a microcapsule type toner having a core material of a pressure fixing substance composed of a liquid or a soft solid, and such a toner has been studied in the past.

This microcapsule toner can be formed into a sphere and can be fixed at a low pressure, as compared with a conventional pressure-fixing toner having a single structure, in which a pressure-fixing substance is manufactured by freezing and pulverization. In addition, there is a possibility that problems such as agglomeration and blocking between toners may be reduced in order to eliminate exposure of the pressure fixing substance. US Pat. No. 3,080,250,308025 describes such a microcapsule toner.
1,3080318, JP-A-48-71648, 48-75032, 51-80235, 51-
81134,51-124435,52-82239,52-113740,54-76233,54
Techniques such as -118249, 58-66948, 59-148066 are disclosed.

The present inventors have studied various methods for microencapsulation, but encapsulation using an interfacial polymerization method has been considered.
Attention was paid to this method because it had the advantages of being able to be performed at room temperature under atmospheric pressure in a short time and without requiring any special equipment.

However, as described above, the method involves polymerization in water to obtain particles, and thus has a drawback of a decrease in electric resistance at high humidity.

As a method for treating the surface of such a toner, Japanese Patent Application Laid-Open
No. 54-76233 discloses a method of treating with a melamine condensate to insolubilize residual polyvinyl alcohol, a method of depositing a ketone-aldehyde resin on a toner surface by a coacervation method, and the like.

However, there is a problem that sufficient electric resistance of the toner cannot be obtained even if the residual polyvinyl alcohol is insolubilized. In addition, the coacervation method requires the use of an organic solvent, and other easy processing methods are required. Was needed.

(Problems to be Solved by the Invention) The present invention improves the non-uniform charging of the toner surface, the hydrophilicity of the toner surface, and the poor triboelectric charging property due to the reduced resistance.
An object is to easily obtain a capsule toner that can be fixed at a low pressure.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides an aqueous dispersion obtained by encapsulating a core material having pressure fixing properties in a shell formed by interfacial polymerization,
An aqueous dispersion obtained by dispersing spherical hydrophobic resin fine particles having a particle diameter of 0.01 to 1 μ in water is mixed, and the hydrophobic resin in the aqueous dispersion is attached to the outer surface of the capsule,
The present invention relates to a powder toner characterized by being coated with a capsule and dried.

In the present invention, the core material having a pressure fixing property is a liquid or soft solid material in which the core material flows or is extruded when the capsule is broken,
It is composed of a coloring agent magnetic powder such as a dye and a pigment, a binder, a solvent and the like.

As the coloring agent, dyes and pigments conventionally used in toner materials are used. Zinc yellow, yellow iron oxide, Hansa yellow, disazo yellow, quinoline yellow, permanent yellow, permanent red, red bengal, lithol red, watch yang Red Ca salt, Watchang red Mn salt, pyrazolone red, lake C, lake
Pigments such as D, brilliant carmine 6B, brilliant carmine 3B, navy blue, phthalocyanine blue, metal-free phthalocyanine, titanium oxide, carbon black, and oil-soluble dyes can be used.

As the magnetic powder, various alloys or compounds such as iron, zinc, cobalt, nickel, and manganese such as ferrite, magnetite, and hematite can be used.

These magnetic powders are preferably spherical or cubic, octahedral, needle-like, and have an average particle size of 0.1 to 0.5 micron, and are subjected to a surface treatment such as a fatty acid or the like to have good dispersion in the resin solution. Hydrophobic treatment, silane coupling agent treatment, resin coating treatment and the like may be applied.

Adhesives have the function of dispersing and holding a colorant or magnetic powder well and fixing a visible image on paper. Ethylene-vinyl acetate copolymer, polystyrene, styrene and acrylate, methacrylic Copolymers containing styrene with acid esters, acrylonitrile or maleic acid esters, polyacrylates, polymethacrylates, polyesters,
Examples thereof include polyamide-based, polyvinyl acetate-based, epoxy-based, phenol-based, hydrocarbon-based, and petroleum-based resins, which can be used alone or in combination.

Examples of the wax include polyethylene wax, polypropylene wax, microcrystalline wax, paraffin wax, oxidized wax, vegetable wax, animal wax, mineral wax, and the like. If necessary, these waxes can be used alone or in combination.

The solvent is preferably one that dissolves or swells the binder, but any solvent that does not dissolve the binder can be used as a part of the solvent.

Solvents include hydrocarbon solvents such as phthalate ester, phosphate ester, fatty acid ester, benzoate ester, citrate ester, diarylalkane, alkylphenyl ether, polybutene, vegetable oil, toluene and xylene. Etc. can be used.

The core material of the present invention can contain various additives as required, and examples thereof include catalysts such as tin octenoate and dibutyltin dilaurate, and release agents composed of silicon compounds and fluorine compounds. be able to.

The above core material is dispersed by heating or cooling the colorant, magnetic powder, binder, solvent, and other additives with a disperser such as a ball mill, attritor, dyno mill, or three-roll mill, if necessary. It can be obtained by:

In the interfacial polymerization in the present invention, a hydrophobic polymerizable compound is dissolved and dispersed in the above-mentioned core substance, and an aqueous medium containing a dispersion stabilizer is mixed and emulsified by stirring. The polymerization is carried out with a hydrophobic polymerizable compound.

Examples of the hydrophobic polymerizable compound include phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, dimethoxybiphenyl diisocyanate, dimethylphenylmethane dicyanate, xylylene diisocyanate, diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, and hexamethylene diisocyanate. Methylene diisocyanate, propylene diisocyanate, butylene diisocyanate, ethylidene diisocyanate, cyclohexylene diisocyanate, toluylene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, dimethyldiphenylmethane tetraisocyanate, prepolymer of polyisocyanate, tetramethylene Diisothiocyanate, hexamethylene diisothiocyanate, p- phenylenediisothiocyanate, xylene-1,4-diisothiocyanate,
Urethane-based and urea-based shell-forming compounds such as ethylidin diisocyanate; epoxy-based shell-forming compounds marketed under the trade names such as Epicoat; oxazoloyl chloride, succinoyl chloride, adipoyl chloride; Sebacoyl chloride, phthaloyl chloride, isophthaloyl chloride, fumaroyl chloride, cyclohexanedicarbonyl chloride, polyester having an acid chloride group, polyamide, benzenedisulfonyl chloride, naphthalenedisulfonyl chloride, oxybisbenzenedisulfonyl chloride,
Hexane disulfonyl chloride, ethylene bis (chloroformate), tetramethylene bis (chloroformate), 2,2'-dimethyl-1,3-propanebis (chloroformate), p-propanebis (chloroformate) Polyamide shell-forming compounds such as
One or two or more can be used in combination.

These compounds can be added when preparing a dissolved dispersion of the core substance. However, immediately before mixing and stirring with water containing a dispersion stabilizer, the dissolved dispersion of the core substance is prepared. Is preferably added. The dissolved dispersion obtained by mixing the core substance and the polymerizable compound is mixed and stirred with an aqueous medium having a dispersion stabilizer.

Examples of the dispersion stabilizer include polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethylcellulose, carboxymethylcellulose, cellulose gum, silica fine powder, water-soluble polymer compounds such as sodium lauryl sulfate and sodium oleate, metal oxides, and surfactants. . These dispersion stabilizers have the effect of miniaturizing particles and making the particle size uniform.

The mixing and stirring can be performed by adding the dispersing solution of the core substance to the aqueous medium having the dispersion stabilizer, or conversely, by adding the aqueous medium having the dispersion stabilizer to the dissolving dispersion. it can.

The mixing and stirring can be performed by a high-speed stirrer or an ultrasonic disperser. As a high-speed stirrer, a homomixer,
A homogenizer, a colloid mill, a homodisper, etc. can be used, and stirring is performed for several thousand revolutions or more.

The above-mentioned emulsification by mixing and stirring can be performed at room temperature, but if necessary, conditions such as heating, reduced pressure, or increased pressure can be added.

When isocyanate is used as the hydrophobic polymer compound, it is preferable to heat and react the isocyanate with water in the presence of a catalyst after emulsification in order to strengthen the capsule film.

Further, when the viscosity of the core material is reduced by using a low-viscosity solvent in order to reduce the particle size by the mixing and stirring, heating may be performed for the purpose of removing the solvent having a viscosity from the core material. It is valid.

As described above, a finely divided spherical core material is generated in the aqueous medium.

While maintaining gentle stirring such that the core substance in the aqueous medium does not precipitate, the hydrophilic polymerizable compound that undergoes a polymerization reaction with the hydrophobic polymerizable compound is added thereto.

Hydrophilic compounds that undergo such a polymerization reaction include:
Of polyamines such as ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, phenylenediamine, 2-hydroxytrimethylenediamine, diethylenetriamine, triethylenetetraamine, diethylaminopropylamine and tetraethylenepentane, piperazine, methylpiperazine and dimethylpiperazine Piperazines, ethylene glycol, catechol, resorcinol, hydroquinone, dihydroxymethylbenzene, dihydroxyethylbenzene, naphthalene diol, polythiol and the like are used.

This polymerization reaction proceeds at room temperature, but may be heated.

When a polybasic acid is used as the hydrophobic polymerizable compound, it is preferable to add a small amount of an acid neutralizer such as sodium carbonate.

After the completion of the polymerization reaction, the remaining hydrophilic polymerizable compound, dispersion stabilizer and the like are washed. Washing with water,
For example, hot water washing or the like is performed by decantation three to four times or centrifugation.

The particles encapsulated by the interfacial polymerization are mixed with an aqueous resin dispersion in which fine resin particles that become hydrophobic when dried are dispersed in water, and the resin in the resin dispersion is attached to the outer surface of the capsule, Cover the capsule.

As such an aqueous resin dispersion, a dispersion produced by so-called soap-free emulsion polymerization containing no activator or the like can be used as it is or after being concentrated.

A dispersion obtained by such a soap-free emulsion polymerization is a dispersion obtained by a technique disclosed in Japanese Patent Application Laid-Open No. 58-127702, 59-1503, 59-199703, etc. The particles are spherical, about 0.01 to 1μ,
Those having a uniform particle size are preferred for obtaining a uniform film.

The resin in the resin dispersion is made of styrene-methyl methacrylate copolymer, which covers the outer surface of the capsule and contributes to improving the moisture resistance of the toner or the fixation of the capsule shell. Isobutyl methacrylate-methyl methacrylate copolymer is preferred.

It is also effective to use two or more kinds of aqueous resin dispersions for the purpose of changing the properties of the outer surface of the toner from various aspects with resin fine particles having different properties.

In addition, what polymerized using the following vinyl monomers can also be used.

That is, vinyl monomers include styrene monomers such as styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, Monobasic acids such as acrylic acid or alkyl methacrylate, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, acrylic acid, methacrylic acid, crotonic acid, fumaric acid, itacone Ethylenically unsaturated carboxylic acid monomers such as dibasic acids such as acid and maleic acid or anhydrides thereof, N-methylolacrylamide, N-methylolmethacrylamide, N-butoxymethyl N-substituted (meth) acrylic monomers such as acrylamide and N-butoxymethylmethacrylamide; hydroxyl-containing monomers such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; glycidyl acrylate, glycidyl methacrylate And other epoxy group-containing monomers.

The above resin dispersion was used for capsules 10 obtained by interfacial polymerization.
0.3 to 10 parts by weight based on the solid fraction relative to 0 parts by weight. 0.
If the amount is less than 3 parts by weight, the surface of the capsule cannot be sufficiently coated, and if the amount is more than 10 parts by weight, the effect just added cannot be obtained. In addition, the capsules may aggregate.

The method of applying the resin of the resin dispersion to the surface of the capsule and coating the surface of the capsule is to mix the aqueous resin dispersion with the aqueous resin dispersion of the capsule, stir, and dry with a spray dryer. Is obtained by

In the case of spray drying, even if the fine resin particles in the resin dispersion liquid do not adhere to the outer surface of the capsule but partially enter the toner, the fine resin particles have an effect as a charging aid. A favorable effect can be obtained.

The powder toner of the present invention can also be obtained by removing water by filtration or the like, drying by vacuum drying, hot-air drying or the like without using a spray dryer, and then crushing the dried product.

After mixing the dispersion of the capsule obtained by the interfacial polymerization with the aqueous resin dispersion, addition of a solvent, pH adjustment,
An operation of adhering the resin in the aqueous resin dispersion around the capsule by means such as heating or cooling, adding flocculation, or charging the particles may be used.

In the present invention, a charge control agent can be used for the core material or the outer shell of the capsule for charge control.

As such charge control agents, oil-soluble dyes, metal-containing dyes, acid dyes, metal salts of naphthenic acid, fatty acid metal soaps and the like are used.

In addition, hydrophobic silica for the purpose of fluidity modification, carbon random, alumina, cerium oxide, etc. as abrasives,
Further, fine particles such as metallic soap powder, polyvinylidene fluoride and polytetrafluoroethylene can also be used as the lubricant.

Hereinafter, embodiments of the present invention will be described. In the examples, parts indicate parts by weight.

Example 1 Synthetic wax (Sunwax 131-P manufactured by Sanyo Chemical Industries) 5 parts Ethylene-vinyl acetate copolymer (containing 30% vinyl acetate) 5 parts Petroleum-based resin (Corporex # 2100 Toho Petroleum Resin) 5 parts Dioctyl phthalate 10 parts High boiling point solvent (Hisol 100 manufactured by Nippon Petrochemical) 20 parts Magnetic powder (EPT-500 manufactured by Toda Kogyo) 40 parts The mixture of the above formulation was dispersed in a three-roll mill to obtain a soft ink. (Ink A) Isocyanate (Millionate MR)
After adding and mixing 70 parts of Nippon Polyurethane Co., Ltd., and mixing with 1200 parts of a 0.75% aqueous polyvinyl alcohol solution, emulsify at 10,000 rpm for 5 minutes with Colloidal (Nippon Seiki Desktop Colloid Mill). Done.

After the emulsification, the emulsified liquid was transferred to another container, and 180 parts of a 10% aqueous solution of diethylenetriamine was added thereto while stirring at a low speed, followed by stirring for 3 hours to produce microcapsules by an interfacial polymerization reaction.

After standing overnight, the supernatant was removed, and the operation of stirring and washing with warm water at 50 ° C. and decanting was repeated four times to adjust the pH of the emulsion to about 6.

After the supernatant was removed so that the solid content of the microcapsules in the emulsion was 30%, an aqueous resin dispersion (VE-2029) was obtained.
Styrene-methyl methacrylate copolymer, particle size approx.
A 4μ spherical 20% dispersion (manufactured by Soken Chemical Co., Ltd.) was mixed at 3% with respect to the solid content of the microcapsules.

The above mixture was spray-dried at an inlet temperature of 140 ° C. using a spray dryer (Palvis GA-31 manufactured by Yamato Scientific Co., Ltd.).

0.3% of colloidal silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was added to the powder obtained by spray drying,
Commercially available copier (U-BiX120 manufactured by Konishi Roku Photo Industry Co., Ltd.)
A print test was performed at 0), and when the unfixed image was fixed with a pressure roll, a good image without fog could be obtained.

Comparative Example 1 In Example 1, spray drying was performed without adding an aqueous resin dispersion. Add colloidal silica (R-972) to the obtained powder.
Example 1 with 0.3% addition of Nippon Aerosil Co., Ltd.)
A similar test was performed, but little image was obtained.

Comparative Example 2 In Example 1, as a water-based resin dispersion, Seixen A (a self-emulsifiable polyolefin having a particle size of several microns) was used, but the capsule was not covered because the resin particles were coarse. Was enough.

Comparative Example 3 In Example 1, N, N-dimethylol urea was added in place of the aqueous resin dispersion to insolubilize residual polyvinyl alcohol, but the toner resistance was lower than that of the powder of Comparative Example 1. Observed and almost no images were obtained.

Comparative Example 4 In Example 1, the microcapsules obtained by interfacial polymerization were washed, water was removed, and then washed with methanol.

This was made into a dispersion having a solid content of 25% in methanol, and then a methanol solution of a ketone-aldehyde resin was added so as to have a solid content ratio of 3% by weight based on the solid content of the microcapsules. .

Next, water is added to the methanol dispersion to obtain a ketone-
The aldehyde resin was deposited on the microcapsules. This dispersion was spray-dried. However, when the microcapsules were washed with methanol, the core component in the capsules was dissolved through the shell in methanol, so that only sticky powder was obtained by spray drying.

It was also confirmed that the resistance was lower than that of Comparative Example 1.

Comparative Example 5 The powder obtained by spray drying in Comparative Example 1 was dispersed in a 5% dispersion of VE-2029 (manufactured by Soken Chemical Co., Ltd.), and spray drying was attempted. The powder obtained by spray drying is VE-2
When mixed with the dispersion of No. 029, no coagulation occurred, and the nozzle of the spray dryer was frequently clogged.

Example 2 Paraffin wax (SP-0145 Nippon Seiro Co., Ltd.) 5 parts Ethylene-vinyl acetate copolymer (vinyl acetate 30%) 8 parts Polybutene oil (Nippon Oil LD-10) 20 parts Isopar M 10 parts Toluene 5 Part Magnetic powder (BL-220 Titanium Industry Co., Ltd.) 40 parts The mixture of the above formulation was dispersed in a three-roll mill to obtain a soft ink. (Ink B) Thereafter, the same treatment as in Example 1 was performed to obtain a capsule toner coated with hydrophobic resin fine particles from an aqueous resin dispersion.

Colloidal silica (R-972 Nippon Aerosil Co., Ltd.)
Was added, and the same printing test as in Example 1 was carried out. As a result, a good image without fog could be obtained.

Further, even when the present capsule toner was left in an environment at 30 ° C. and a relative humidity of 70%, no decrease in image density, etc., which might be caused by moisture absorption, was observed.

Example 3 Petroleum resin (DRA-100P manufactured by Toho Petroleum Co., Ltd.) 2 parts Paraffin wax (SP-0145 Nippon Seiro Co., Ltd.) 7 parts Carnauba wax (Powder 1 Nippon Seiro Co., Ltd.) 55 parts Toluene 30 parts Magnetic powder (MAT305 Toda Kogyo Co., Ltd.) 40 parts Diisopropylnaphthalene 10 parts The mixture having the above formulation was melt-dispersed with a homodisper.

To 200 parts of the molten dispersion, 45 parts of a heated isocyanate (same as in Example 1) was added and mixed and dissolved.
The mixture was added to 1500 parts of a 2% aqueous solution of polyvinyl alcohol heated to ℃, and emulsified at 10,000 rpm for 3 minutes using a homomixer (UH-10 manufactured by Nippon Seiki Co., Ltd.).

After emulsification, 150 parts of a 10% aqueous solution of diethylenetriamine was added, and stirring was continued for 3 hours to produce microcapsules by an interfacial polymerization reaction.

Thereafter, an aqueous resin dispersion was coated by the same operation as in Example 1. When the same printing test as in Example 1 was performed, a good image without fog could be obtained.

Example 4 Synthetic wax (Sunwax 131-Sanyo Chemical Co., Ltd.)
5 parts Polybutene oil (LV-10 manufactured by Nippon Oil Co., Ltd.) 40 parts Lecithin 2 parts Carbon black (manufactured by Mogal Cabot Corporation) 2 parts Magnetic powder (BL-220 Titanium Industry Co., Ltd.) 40 parts Was dispersed in a three-roll mill to obtain a soft ink. (Ink D) 7 parts of terephthaloyl chloride was placed in 12 parts of heated dibutyl phthalate to dissolve the solution, and this liquid was dispersed in the above-mentioned ink D7.
0 parts were mixed.

This mixture was poured into a 2.0% aqueous solution of polyvinyl alcohol heated to 70 ° C., and emulsified by high-speed stirring at 10,000 rpm for 3 minutes using a homomixer (UH-10 manufactured by Nippon Seiki Co., Ltd.).

4 parts of diethylenetriamine and 2 parts of sodium carbonate
Was dissolved in 20 parts of water and added.

Stirring was performed at low speed for 10 hours to produce capsule particles by interfacial polymerization.

After washing the emulsion containing the capsules and repeating the decantation four times, the solid content of the capsules was reduced to about 35%, and an aqueous resin dispersion (ME-3100-2) was added to the solid content of the capsules. 20% (manufactured by Soken Chemical Co., Ltd.) was added at a solid fraction of 6%, and spray drying was performed.

0.3% of colloidal silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was added to the powder obtained by spray drying,
When a printing test was performed in the same manner as in Example 1, a good image without fog was obtained.

In addition, there was no decrease in the resistance of the toner, which is considered to be caused by the residual polyvinyl alcohol, and no decrease in the density due to poor moisture resistance.

Example 5 A powdery toner was obtained in the same manner as in Example 1, except that hexamethylenediamine was used instead of diethylenetriamine.

 The same effect as in Example 1 was obtained.

Example 6 Ethylene-vinyl acetate copolymer (same as Example 1) 5 parts Synthetic wax (same as Example 1) 5 parts Petroleum resin (same as Example 1) 5 parts High boiling solvent (same as Example 1) 20 parts Diisopropylnaphthalene 10 parts Magnetic powder (BL-220 Titanium Industry Co., Ltd.) 40 parts The mixture of the above formulation was dispersed in a three-roll mill to obtain a soft ink. (Ink E) To 320 parts of this ink E, 15 parts of toluene, 0.06 part of dibutyltin dilaurate, isocyanate (Millionate MR-20)
After adding and mixing 50 parts of Nippon Polyurethane Co., Ltd., 100 parts of a 0.75% aqueous polyvinyl alcohol solution is added thereto, and gently stirred.

This emulsified liquid is treated with a 0.75% aqueous solution of polyvinyl alcohol 130
In 0 part, emulsification was performed for 3 minutes with a colloid mill at 10,000 rpm to obtain particles having an average particle size of 14 μm.

This emulsion is heated while stirring at low speed to confirm foaming due to the reaction between isocyanate and water. After heating and reacting for about 1 hour while foaming the emulsion, add 150 parts of 10% aqueous solution of diethylenetriamine,
The foaming was stopped and stirring was continued for about 3 hours to produce capsules by interfacial polymerization.

After leaving the dispersion liquid of the capsules overnight, washing with hot water and decantation were repeated four times to adjust the solid content of the capsules to 50%.

An aqueous resin dispersion VE- was added to the dispersion thus prepared.
2029 (same as in Example 1) was mixed and dispersed so as to have a solid fraction ratio of 5%, and was spray-dried with a spray drier at an inlet temperature of 140 ° C.

The powder obtained by spray drying has a uniform hydrophobic coating of a styrene-methyl methacrylate copolymer resin on the outer surface of a shell formed by interfacial polymerization.

0.3% of colloidal silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was added to the above powder, and the same printing test as in Example 1 was performed. As a result, a good image without fog was obtained.

Example 7 In Example 6, the mixed dispersion of the capsule dispersion and the aqueous resin dispersion was not subjected to spray drying, but water was removed by filtration under reduced pressure, followed by drying in a vacuum dryer.

The dried aggregate was crushed by a crusher to obtain a powder coated with a styrene-methyl methacrylate copolymer resin.

Although the crushing process was started, some crushing-defective particles were observed, but almost the same image as in Example 6 was obtained.

Example 8 Instead of the isocyanate of Example 1, Coronate L
The same test was carried out below except that (Nippon Polyurethane Co., Ltd.) was used.

Example 9 Instead of the isocyanate of Example 1, use millionate
Except for using a 50:50 mixture of MR-200 and Coronate L,
Hereinafter, the same test was performed.

Example 10 In Example 6, VE-2029 and M-20 were used as aqueous resin dispersions.
E-3100-2 (manufactured by Soken Chemical Co., Ltd.) was added in an amount of 3% by solid fraction, and the same test was performed.

[Effects of the Invention] According to the present invention, toner particles encapsulated by an interfacial polymerization method can be easily fixed at a low pressure.

In addition, capsule particles produced by the interfacial polymerization method can be treated in the state of an aqueous dispersion, and can be coated without passing through a drying step and a crushing step.

Further, since the aqueous resin dispersion can be used as it is obtained by emulsion polymerization, it is inexpensive because it does not go through the steps of drying and collecting for powdering fine particles.

In addition, the process of agglomeration of fine particles generated during pulverization for obtaining fine resin particles from an aqueous resin dispersion and the step of crushing the fine particles can be omitted, and therefore, it is easy to uniformly adhere the particles to the capsule surface.

Furthermore, after drying the aqueous resin dispersion, a residue of the dispersion stabilizer used in emulsification of the core substance is present on the capsule surface in order to form a high-resistance coating having good moisture resistance after drying. However, a toner having good moisture resistance can be obtained.

Claims (1)

(57) [Claims] An aqueous dispersion obtained by encapsulating a core substance having a pressure fixing property in a shell formed by interfacial polymerization,
An aqueous dispersion obtained by dispersing spherical hydrophobic resin fine particles having a particle diameter of 0.01 to 1 μ in water is mixed, and the hydrophobic resin in the aqueous dispersion is attached to the outer surface of the capsule,
Powder toner characterized by being coated with a capsule and dried.