JPH0820755B2 - Method for manufacturing capsule toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) 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 easily fixes on a paper surface or the like under a pressure in which a shell is formed 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 toner by melt-kneading, cooled, and then 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, it is said that the spray-drying method produces spherical toner, which gives a uniform charge and good fluidity. And the like, the consumption of heat energy required for drying is enormous, the solvent remains in the toner after drying, and it is difficult to remove, and the physical properties of the toner are sufficient. However, there is a restriction on the material when applying the toner, and it is difficult to obtain a toner having sufficient characteristics only by this method.

Various methods for producing spherical toner particles in water have been investigated by emulsion polymerization method, suspension polymerization method, interfacial polymerization method, and the like. Dispersants and stabilizers used in the production of toner particles in water are being investigated. Remain on the surface of the toner particles and are difficult to remove. This absorbs moisture in the air to lower the electrical resistance of the toner, making copying on plain paper difficult and making the charge on the toner surface uneven. It has been pointed out. In addition, it has been pointed out that spherical particles have poor cleaning characteristics on the surface of the photoconductor.

Further, with the speeding up of the electrophotographic system or in unmanned machines such as facsimile machines, a system for fixing toner by crushing toner with a pressure roll has been reviewed from a system for fixing by conventional heating. This method does not require warm-up of the machine, requires less energy for fixing, and can cope with high speed.

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.

Compared with the conventional pressure-fixing toner having a single structure, which is manufactured by freeze-pulverizing a pressure-fixing substance, this microcapsule toner can be spherical and can be fixed at low pressure. In addition, since the exposure of the pressure-fixing substance is eliminated, problems such as aggregation and blocking of toner particles may be reduced. For such microcapsule toners, see US Pat.
1,3080318, JP-A-48-71648, 48-75032, 51-80235, 51-
81134,51-124435,52-82239,52-113740,54-76233,54
The technology is disclosed in the publications such as -118249, 58-66948, 59-148066.

The present inventors have studied various methods as a microencapsulation method, but encapsulation by the interfacial polymerization method can be performed at atmospheric pressure in a short time and without requiring a special device. Because of its advantages such as ru, we paid attention to this method.

However, as described above, this method has a drawback that the particles are polymerized in water to obtain particles, so that the electrical resistance at high humidity is lowered.

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

However, there is a problem that even if the residual polyvinyl alcohol is insolubilized, sufficient electric resistance of the toner cannot be obtained. Further, in the coacervation method, the use of an organic solvent is indispensable and the toner has a liquid core substance. In the capsules, even the solvent of the core substance was washed with the organic solvent, and a decrease in fixing property due to solidification of the core substance was unavoidable.

(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.

[Structure of Invention]

(Means for Solving the Problem) The present invention comprises a wax-like substance which is heat-melted at a temperature of 50 to 100 ° C. and exhibits pressure fixing property at room temperature, and a colorant or a magnetic material is dispersed in the wax-like substance. A step of making a core substance into a liquid state by heat melting with an organic solvent having a boiling point of 100 ° C. or higher, mixing heated isocyanate with the mixture, and emulsifying the mixture by stirring with hot water having a dispersion stabilizer. Step, a step of adding a hydrophilic compound that reacts with the isocyanate to the above emulsion and performing encapsulation by interfacial polymerization, followed by cooling
The present invention relates to a method for producing a capsule toner, which comprises washing with an organic solvent at 100 ° C or lower.

In the present invention, the core material having a pressure fixing property is a solid substance at room temperature and is composed of a coloring agent such as a dye or a pigment, magnetic powder, a heat-melting pressure fixing material, a solvent and the like.

As the colorant, 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 iron oxide, resole red, watch Red Ca Salt, Watchyan Red Mn Salt, Pyrazolone Red, Laked C, Laked
Pigments such as D, Brilliant Carmine 6B, Brilliant Carmine 3B, Navy Blue, Phthalocyanine Blue, Metal-Free Phthalocyanine, Titanium Oxide, Carbon Black, or oil-soluble dyes can be used. For black toner, magnetic powder It can be used as a substitute for the colorant alone.

As the magnetic powder, various ferrites, magnetite, hematite, and other iron, zinc, cobalt, nickel, alloys or compounds of manganese, and the like 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.

The heat-fusible pressure-fixing substance has the function of holding the colorant or magnetic powder in a well-dispersed state and fixing the visible image on the paper surface. It is solid. Wax is typically used as such a pressure-fixing substance, and 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 desired, they can be used alone or in combination.

Further, as the solvent, those which dissolve the pressure fixing substance are preferable, but those which do not dissolve the binder can be used.

If the boiling point of the solvent is not 100 ° C or higher, it is likely to evaporate when the core substance is melted by heat, which is not preferable. Solvents are hydrocarbon solvents such as phthalate ester, phosphate ester, fatty acid ester, benzoate ester, citrate ester, diarylalkane, alkyl phenyl ether, polybutene, vegetable oil, toluene, xylene, etc. 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-mentioned core substance is heated with a colorant, magnetic powder, pressure-fixing substance, solvent, and other additives in a dispersing machine such as a high-speed stirrer such as homodisper, a ball mill, an attritor, a dyno mill, or a three-roll mill, if necessary. And then dispersed.

In the present invention, the interfacial polymerization is carried out by melting the above core substance into a liquid state by heat melting, then melt-dispersing the heated isocyanate compound, and mixing and stirring with hot water containing a dispersion stabilizer to emulsify the hydrophilic compound after emulsification. The isocyanate compound is polymerized with a polymerizable polymerizable compound.

Examples of the above-mentioned isocyanate compound include phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, dimethoxybiphenyl diisocyanate, dimethyldiphenylmethane diisocyanate, xylylene diisocyanate, diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene diisocyanate, butylene diisocyanate. , Ethylidyne diisocyanate, cyclohexylene diisocyanate, toluylene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, dimethyldiphenylmethane tetraisocyanate, polyisocyanate prepolymer, tetramer Urethane-based and urea resin-based shell-forming compounds such as diisocyanate, hexamethylene diisothiocyanate, p-phenylene diisothiocyanate, xylene-1,4-diisothiocyanate, and ethylidyne diisocyanate are used. Or it can be used in combination of 2 or more types.

These compounds can be added when preparing a melt dispersion of the core substance, but the melt dispersion of the core substance is prepared immediately before the melt dispersion of the core substance is produced and mixed with hot water having a dispersion stabilizer. It is preferable to add the solution by heating it. The molten dispersion obtained by mixing the core substance and the isocyanate compound is mixed and stirred with hot water having a dispersion stabilizer.

Examples of dispersion stabilizers include polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose, cellulose gum, fine silica 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.

Mixing and stirring can be performed either by adding the molten dispersion of the core substance to hot water containing the dispersion stabilizer, or conversely, by adding hot water containing the dispersion stabilizer to the molten dispersion. it can.

Mixing and stirring can be performed with a high-speed stirrer or an ultrasonic disperser. As a high-speed stirrer, a homomixer,
A homogenizer, a colloid mill, a homodisper, or the like can be used, and stirring is performed for several thousand revolutions or more.

The emulsification by mixing and stirring is performed in hot water, but if necessary, conditions such as reduced pressure or increased pressure can be added. The presence of the catalyst has the effect of promoting the reaction between isocyanate and hot water and strengthening the capsule film.

In addition, it is advantageous to reduce the viscosity of the core substance in order to reduce the particle size by mixing and stirring, and increasing the amount of the solvent for reducing the particle size is also effective.

As described above, the atomized spherical core material is generated in hot water.

While continuing the gentle stirring to such an extent that the core substance in the hot water does not precipitate, a hydrophilic polymerizable compound that polymerizes with the isocyanate compound is added thereto.

Hydrophilic compounds that undergo such a polymerization reaction include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, phenylenediamine, 2-hydroxytrimethylenediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine, tetraethylene. Polyamine such as pentane, piperazine, methylpiperazine, piperazine of dimethylpiperazine, ethylene glycol, catechol, resorcinol, hydroquinone, dihydroxymethylbenzene, dihydroxyethylbenzene, naphthalenediol, polythiol and the like are used.

This polymerization reaction proceeds even at hot water temperature, but cooling is also possible.

Thereafter, the temperature is lowered or forcedly cooled so that the temperature is lower than the melting point of the pressure-fixing substance, and the encapsulation is completed.

After the encapsulation is completed, the remaining hydrophilic polymerizable compound, dispersion stabilizer, etc. are washed. Washing with water, warm water, etc. by decantation 3 to 4 times or
It can be exemplified by performing centrifugation or the like.

Further, since the core substance according to the present invention has pressure fixing property even if it does not contain a large amount of solvent or does not contain any solvent, it is acceptable to wash the high boiling point organic solvent in the core substance together with the washing of the capsule shell. .

The washing of the capsule with such an organic solvent has the effect of reducing the hydrophilicity of the outer shell and facilitates the drying of the capsule.

The core substance of the present invention, however, partially retains the high-boiling point organic solvent in the pressure-fixing substance even if it is washed with a low-temperature volatile organic solvent, so that the crushing of the toner during pressure fixing can be suppressed to a low pressure. In addition to being expected to be carried out, it is possible to increase the fixing property on the paper surface over time.

To take out the encapsulated toner particles,
Examples include a method of crushing with a crusher after filtration, drying (vacuum drying, warm air drying), and a method with a spray dryer.

However, when drying, it is necessary to dry the encapsulated toner at a temperature below the melting temperature, and from this point, washing with a low-temperature volatile organic solvent is preferable.

As such an organic solvent, alcohols such as methanol, ethanol and isopropyl alcohol, and ketones such as acetone and methyl ethyl ketone are preferable.

In the present invention, a charge controlling agent can be used in 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.

Hydrophobic silica, abrasives such as carborundum, alumina, and cerium oxide are also used for the purpose of fluidity modification, and metal soap powder, polyvinylidene fluoride, polytetrafluoroethylene, and other fine particles are also used as lubricants. It can be used together.

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

Comparative Example 1 Synthetic wax (Sun Wax 131-P manufactured by Sanyo Kasei Co., Ltd.) 5 parts Ethylene-vinyl acetate copolymer (containing 30% vinyl acetate)
5 parts Petroleum resin Si (Corporex # 2100 manufactured by Toho Petroleum Resins) 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 was dispersed with a three-roll mill to obtain a room temperature ink-like material.

After adding 70 parts of isocyanate (Millionate MR-200 Nippon Polyurethanes Co., Ltd.) to 300 parts of the above ink-like material and mixing, 0.75% polyvinyl alcohol aqueous solution (25
In addition to 1200 parts, colloid mill (Nippon Seiki Co., Ltd.)
Emulsification was carried out for 5 minutes at 10,000 rpm with a tabletop colloid mill.

After 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.

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 conducted in 0), but almost no image was obtained.

Comparative Example 2 After washing the microcapsules obtained by the interfacial polymerization in Comparative Example 1, water was removed and then washed with methanol.

After making this a dispersion liquid with a solid content of 25% in methanol,
A methanol solution of ketone-aldehyde resin was added at 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 3 After washing the microcapsules obtained by interfacial polymerization in Comparative Example 1, water was removed and then washed with methanol, and then,
It was washed with cyclohexane, filtered, and vacuum dried.

The solvent in the capsule was washed out by washing with methanol and cyclohexane.

The microcapsules obtained by crushing had fluidity, no image was obtained by the printing test, and no fixing occurred even when pressure fixing was performed.

Example 1 Paraffin wax (SP-0145 manufactured by Nippon Seiro Co., Ltd.)
5 parts Carnauba wax (Powder-1 Nippon Seiro Co., Ltd.)
55 parts Magnetic powder (MAT305 manufactured by Toda Kogyo Co., Ltd.) 40 parts The mixture of the above formulation was melt-dispersed at 90 ° C. with a homodisper.

To 200 parts of the above melt dispersion, 40 parts of heated Hysol 100 (high boiling point solvent manufactured by Nippon Petrochemical Co., Ltd.) and heated isocyanate (Coronate 3041 Nippon Polyurethane Co., Ltd.)
45 parts) were mixed and dissolved, and then heated to 90 ° C.
In addition to 1500 parts of a 5% aqueous polyvinyl alcohol solution, a homomixer (UH-10 Nippon Seiki Co., Ltd.) was used to perform emulsification at 10,000 rpm for 3 minutes.

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

After washing with water and decantation three times, dehydration was performed, and washing with methanol was repeated twice, followed by filtration, drying and crushing.

The colloidal silica (R-
972 0.3% of Nippon Aerosil Co., Ltd. was added, and a printing test was conducted with a commercially available copying machine (U-Bix1200 Konishi Roku Photo Co., Ltd.), and the unfixed image was taken out and pressure fixing machine ( It was fixed by PC-30 Canon Inc.

 Copies were obtained with good images and good fixability.

Example 2 In Example 1, 1 part of silicone oil KF-96 (manufactured by Nippon Silicon Co., Ltd.) was added.

The same test was performed below, and good images and fixability were obtained. It was confirmed that the slipperiness on the fixing surface was better than that of Example 1.

Example 3 The same test was performed as in Example 1 except that the isocyanate of Example 1 was replaced with Millionate MR200.
Similar to the above, good results were obtained.

Example 4 The same test as in Example 1 was carried out, except that the isocyanate of Example 1 was replaced with a 50:50 mixture of Millionate MR200 and Coronate 3041.

〔The invention's effect〕

According to the present invention, since the toner particles are encapsulated by the interfacial polymerization method, fixing can be easily performed at a low pressure.

In addition, since it is washed with an organic solvent, the hydrophilic property of the capsule surface can be replaced.

Further, since the solvent component remains in the core substance, fixing is easily performed at a low pressure, and then the fixing property is increased on the paper surface.

Claims (1)

[Claims] 1. A core substance comprising a wax-like substance which is heat-melted at a temperature of 50 to 100 ° C. and has a solid pressure-fixing property at room temperature, and a colorant or a magnetic material is dispersed in the wax-like substance. 100 ° C
A step of liquefying by heat melting with an organic solvent having the above boiling point, a step of mixing warmed isocyanate with this, and a step of mixing and stirring the mixture with hot water having a dispersion stabilizer to emulsify; Capsule toner characterized in that a capsule obtained by the step of adding a reactive hydrophilic compound to the above emulsion and encapsulating it by interfacial polymerization and then cooling it is washed with an organic solvent having a boiling point of 100 ° C. or less. Manufacturing method.