JPS58145965A - Capsulated toner - Google Patents

Abstract

PURPOSE:To obtain a capsulated toner for pressure fixing having particularly low offset, by forming shells of a polyurethane resins, polyurea resin, etc. around the core materials contg. hydrophobic silica, display recording materials and a binder. CONSTITUTION:Hydrophobic liquid or a material which dissolves or disperses well in said liquid (material A) and hydrophilic material a material which dissolves or disperses well in said liquid (material B), which materials A and B have the relation of forming an insoluble polyurethane resin, polyamide resin, polyurea resin, etc. by reacting with each other, are used. A dispersion contg. the material A as well as display recording materials which are pigments such as hydrophobic silica, carbon black or the like and magnetic powder, etc. and a binder as core materials is dispersed in a solvent. contg. the material B (polyisocyanate, etc. and catalysts) to form shells of polyurethane, whereby the capsulated toner is obtained. Offsetting performance is thus made low and fixability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner used for converting a latent image formed in an electric or magnetic recording method such as electrophotography or magnetic recording method into a visible image. . More specifically, the present invention relates to capsule toners used for these applications.

Various electrical or magnetic recording methods are known, such as electrophotography, electrostatic recording, or magnetic recording, or are common to many of these methods. The point is that the electrically or magnetically formed latent image is converted into a visible image using toner containing a display recording material such as a colorant in powder or fractional liquid form, and this is transferred to a support such as transfer paper. The image is transferred and fixed onto a medium to form a copied image.

In order to turn a latent image into a visible image using toner, it is generally necessary to use a developer consisting of carrier particles and toner, or a developer consisting only of toner, and an electric or magnetic force that acts between the latent image and the latent image. A method is used in which a toner image is formed on the latent image by attracting toner to the latent image using an attractive force, and the latent image is developed into a visible image. Here, the former developing method using a developer consisting of carrier particles and toner is called a two-component developing method, and the latter developing method using a developer consisting only of toner is called a two-component developing method. There is.

The toner image formed on the latent image is then transferred onto a medium, such as transfer paper, and fused onto the medium. There are three known methods for fixing toner images on media such as transfer paper: heat fixing, solvent fixing, and pressure fixing. The present invention provides a method for manufacturing.

A pressure fusing method in which toner particles are fused onto a medium by applying pressure to the toner particles transferred to the medium is described in U.S. Pat. No. 3,2H,526. Since this method does not use heat or solvent, it does not suffer from the various problems associated with methods such as heat fixing or solvent fixing, and the access time is fast, making it compatible with high-speed fixing methods. It inherently has various advantages.

However, the pressure fixing method has poor fixing properties compared to fixing methods such as heat fixing, and the fixed image easily peels off when rubbed, and requires considerably high pressure for fixing, so it is difficult to use a support like transfer paper. Fatigue of the media is likely to occur due to #M#lt of the media being destroyed, the surface of the supporting media is likely to become excessively glossy, and the pressure roller used to apply high pressure is small. Since there are limits to miniaturization, there are problems in that there are restrictions on miniaturization of the entire copying apparatus.

In order to solve the above-mentioned problems associated with the pressure fixing method, capsule toner in which toner is contained in microcapsules has already been developed. Capsule toner is a toner in the form of microcapsules obtained by forming an outer shell around a core material containing a display recording material such as carbon black, which has the property of being destroyed by the application of pressure. Capsule toner is said to be a toner suitable for the pressure fixing method because it does not require high pressure for fixing and has excellent fixing properties. However, it cannot be said that the performance characteristics that are originally required are necessarily satisfactory.

In other words, the toner used as an electrophotographic developer is required to have good powder properties, excellent developing performance, and not to stain the surface of the photoreceptor, which is the surface on which the Wi image is formed. In the case of a component development method, it is necessary that the surface of the carrier particles used is not contaminated. In addition, the toner used in the pressure fixing method is
It is necessary that the toner has good pressure fixing properties and that the offset phenomenon (a phenomenon in which toner adheres to the pressure roller surface and stains the roller surface) on the pressure roller used for pressure fixing is unlikely to occur. In other words, the toner used in the pressure fixing method has powder characteristics, fixability to support media such as paper (including retention of the fixed image), non-offset property, and chargeability and chargeability depending on the developing method used. All properties such as electrical conductivity and/or electrical conductivity must be at a high level. However, the capsule toners known up to now have not been able to satisfy the characteristics described in the previous section.

The first object of the present invention is to provide a capsule toner having particularly reduced offset properties among these characteristics. Here, offset property refers to the part of the core substance of the capsule toner that is destroyed when the support medium on which the capsule toner adheres and forms an image is passed between hard metal rollers and fixed under pressure. Alternatively, it refers to a phenomenon in which a part of the outer shell of the capsule adheres to the roller surface and causes contamination, and the difficulty of eliminating this offset prevents the practical application of pressure fixing methods that use capsule toner. -・It was also a cause.

A second object of the present invention is to provide a capsule toner that can reduce offset and improve fixing performance. Here, fixability refers to the adhesion of an image formed by capsule toner to a support medium such as paper. That is, fixing of capsule toner is generally carried out by passing the support medium on which the capsule toner has adhered and formed an image, for example, between hard metal rollers and applying pressure to destroy the capsules. , the capsule toners known so far,
This fixation is not always sufficient, and if the copied image peels off when rubbed with a finger, or if the copied image is rubbed by white paper, the colored components of the peeled copy paper may stain the white paper. There was a tendency to Such insufficient fixing properties of conventional capsule toners have been one of the reasons for preventing the practical application of pressure fixing methods using capsule toners.

Furthermore, the present invention provides a capsule toner that has improved offset properties and pressure fixing properties, and also exhibits excellent properties such as not being destroyed by impact within a developing device but easily being destroyed only at the pressure fixing position. You can also
That is the purpose.

As a result of intensive research in order to achieve the above object, the present inventors have discovered that the present invention consists of a core material containing hydrophobic silica, a display recording material, and a binder, and an outer shell formed around the core material. The present invention was achieved based on the discovery that the above-mentioned object can be achieved by a capsule toner having the following characteristics.

Next, the present invention will be explained in detail.

A method for preparing microcapsules by forming an outer shell around a core material containing a display recording material and a binder which is an aid for fusing the display recording material to a support medium in a liquid medium such as water. These known methods can be used to produce the capsule toner of the present invention.

For example, as a method for producing microcapsules that can be used in the present invention, an interfacial polymerization method can be mentioned.

Other examples of methods for producing microcapsules that can be used in the present invention include internal polymerization method, phase separation method,
External polymerization method, melt dispersion cooling method, and coacervation method can be mentioned.

Note that the method for manufacturing microcapsules that can be used in the present invention is not limited to those exemplified above, and other methods for manufacturing microcapsules can also be used. Moreover, these various methods can also be used in combination.

Among examples of methods for producing microcapsules, a preferred method for the present invention is an interfacial polymerization method.

Among these, a particularly preferred method is the method described below.

First, AeI and B substances having the following properties are prepared.

AS quality: @ A substance that is an aqueous liquid itself, or has the property of dissolving or dispersing well in hydrophobic liquids.

Substance B: Hydrophilic liquid itself, or dissolved in hydrophilic liquid or 1. A substance that has the property of being well dispersed.

Substances A and B react with each other to produce polyurethane resins, polyamide resins, polyester resins, polysulfonamide resins, polyurea resins, epoxy resins, and polysulfur resins that are insoluble in both hydrophilic and hydrophobic liquids. It is a substance that has a relationship to form either a carbonate resin or a polycarbonate resin.

Next, a hydrophobic liquid consisting of substance A and a core substance (i.e., a core substance containing hydrophobic silica, a display recording material, and a binder) is dispersed into microdroplets in a wood-philic liquid containing substance B, Next, the wood-philic liquid and the hydrophobic liquid are reacted at the interface of the wood-philic liquid and the hydrophobic liquid by a method such as heating. Hydrophobic silica is formed by forming an outer shell made of polyurethane resin, polyamide resin, polyester resin, polysulfonamide resin, polyurea resin, epoxy resin, polysulfanate resin, or polycarbonate resin that is insoluble in both hydrophobic liquids. A fractional liquid is prepared in which microcapsules (ie, capsule toner) containing a display recording material and a core material containing paint are dispersed.

In the present invention, a particularly preferred combination of substance A and substance B is such that a polyurethane resin or polyurea resin is formed by the reaction of both substances.

Examples of substances A suitable for producing such polyurethane resins or polyurea resins include the following compounds containing an incyanato group or an inthiocyanate group.

(1) Diisocyanate m-phenylene diine cyanate, p-2 lylene diine cyanate, 2.6-1 lylene diine cyanate, 2
．． 4-1 lylene diincyanate, naphthalene-1,4
-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diincyanate, xylylene- 1,4-diisocyanate, xylylene-1°3-diincyanate, 4.4°-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene -1,2-diincyanate, ethyridine diincyanate, cyclohexylene-1,2
-diincyanate, cyclohexylene-1,4-diisocyanate, tolylene diisocyanate, triphenylmethane diisocyanate.

(2) Triincyanate 4.4', 4°'-triphenylmethane triisocyanate, polymethylene polyphenylisocyanate.

(3) Tetraisocyanate 4.4”-dimethyldiphenylmethane-2°2′,5,
5°-Tetraisocyanate.

(4) Polyisocyanate prepolymer adduct of hexamethylene diinocyanate and hexanetriol, 2.
4-Adduct of tolylene diisocyanate and catechol,
Adducts of tolylene diisocyanate and hexanetriol, adducts of tolylene diisocyanate and trimethylolpropane, adducts of xylylene diisocyanate and trimethylolpropane.

(5) Diisothiocyanate tetramethylene dithiocyanate, hexamethylene dithiocyanate, p-phenylene dithiocyanate, xylylene-1,4-diisothiocyanate,
Ethyridine diisothiocyanate.

Similarly, examples of substance B suitable for such a combination include the following compounds.

(1) Water (2) Polyols and polythiols Ethylene glycol, 1,4-butanediol, catechol, resorcinol, hydroquinone, l,2-dihydroxy-4-methylbenzene, 1,3-dihydroxy-5-methylbenzene 1.3 .4-dihydroxy-1-
Methylbenzene, 3゜5-dihydroxy-1-methylbenzene, 2,4-dihydroxy-1-ethylbenzene,
1.3-naphthalenediol, 1.5-naphthalenediol, 2,3-naphthalenediol, 2,7-naphthalenediol, polythiol (3) Polyamine ethylene diamine, tetramethylene diamine.

Pentamethylenecyamine, hexamethylenediamine, p
-phenylenediamine, m-phenylenediamine, 2-
Hydroxytrimethylenediamine, diethylenetriamine, triethylenetetraamine, dimothylaminopropylamine, tetraethylenepentamine, adducts of epoxy compounds and amines.

(4) PiperazinePiperazine, 2-methylpiperazine, 2,5-dimethylpiperazine.

When using multiple types of substances A or B, polyurethane resins or polyurea resins prepared using substances A and B may contain both urethane bonds and urea bonds in their molecular chains, or may contain both urethane bonds and urea bonds. In some cases, the molecular chain contains both thiourethane bonds,
These resins are also included in the expression polyurethane resin or polyurea resin, similar to those having only urethane bonds or urea bonds.

Furthermore, in the above combination of A substance and B substance, A
By replacing the substance with acid chloride, sulfonyl chloride, or bischloroformate as exemplified as the primary substance, an outer shell made of various resin materials such as polyamide resin can also be formed.

(1) Acid chloride oxazoloyl chloride, succinoyl chloride,
Adipoyl chloride, sebacoyl chloride, phthaloyl chloride, 1 inphthaloyl chloride, terephthaloyl chloride, fumaroyl chloride, 1.4
- Cyclohexane dicarbonyl chloride, polyesters with acid chloride functionality, polyamides with acid chloride functionality.

(2) Sulfonyl chloride 1.3-benzenedisulfonyl chloride 11.4-benzenedisulfonyl chloride, 1.5-naphthalenedisulfonyl chloride, 2.7-naphthalenedisulfonyl chloride, p, p'--oxybis(benzenedisulfonyl chloride) sulfonyl chloride), l,6-hexanedisulfonyl chloride.

(3) Bischloroformate ethylene bis(chloroformate), tetramethylene bis(chloroformate), 2,2'-dimethyl-1,3
-Propane bis(chloroformate), p-propane bis(chloroformate).

Furthermore, when dispersing a hydrophobic liquid consisting of substance A and a core substance into microdroplets in a hydrophilic liquid containing substance B, a low boiling point solvent or a polar solvent may be added to the hydrophobic liquid consisting of substance A and a core substance. These low-boiling point solvents or polar solvents, which are preferably mixed together, contribute to promoting the formation of a shell that is a reaction product between substance A and substance B. Examples of low-boiling or polar solvents that can be used for such purposes include methyl alcohol, ethyl alcohol,
Ethyl ether, tetrahydrofuran, dioxane, methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, n-pentane, n-pentane, benzene, petroleum ether, chloroform, carbon tetrachloride, methylene chloride, ethylene chloride, Examples include carbon disulfide and dimethylformamide.

There are no particular restrictions on the material for the outer shell as long as it has the property of breaking under pressure. Copolymers of
Acrylic acid ester copolymer, styrene-methacrylic acid copolymer, styrene fist methacrylic acid ester copolymer,
(styrene/maleic anhydride copolymer, styrene/vinyl acetate copolymer, etc.), polyvinyltoluene resin, acrylic ester homopolymer, methacrylic ester homopolymer, xylene resin, methyl vinyl ether/maleic anhydride resin, vinyl butyral Examples include resin, polyvinyl alcohol resin, and polyvinylpyrrolidone.

Further, the outer shell of the capsule toner may be a double wall made of various polymeric materials. As a double wall particularly preferably used in the present invention, Japanese Patent Application No. 56-1
These are the double wall made of polyurea resin and polyamide resin described in the specification of the No. 65282 application, and the double wall made of polyurethane resin and polyamide resin. A double wall made of a polyurethane resin and a polyamide resin can be produced by, for example, using polyisocyanate and acid chlorite as the A substance and polyamine and polyol as the B substance, adjusting the pH of the emulsifying medium that becomes the reaction liquid, and then heating it. It can be prepared by following the steps below. In addition, the double wall made of polyurea resin and polyamide resin is
Polyisocyanate and acid chloride as substances and B
It can be prepared by using a polyamine as a substance, adjusting the pH of an emulsifying medium serving as a reaction liquid, and then heating it. For details on the manufacturing method of these double walls made of polyurea resin and polyamide resin, and the double wall made of polyurethane resin and polyamide resin, please refer to the patent application filed in 1983.
It is described in the specification of application No.-165262. Such double-walled shells are particularly suitable for forming component-developed capsule toners containing magnetic particles within the core material.

The core material used in the present invention contains hydrophobic silica, a display recording material for converting a latent image into a visible image, and a binder.

Hydrophobic silica is obtained by subjecting the surface of silica to a hydrophobic treatment, and examples include hydrophobic silica (RT-972) sold by Nippon Aerosil Co., Ltd.

The display recording material usually uses a coloring agent that forms a visible image as it is, but it is also possible to use a substance that indirectly forms a visible image, such as a fluorescent substance.

As the coloring agent, dyes and pigments conventionally used in dry or wet toners can be used. For example, as a black toner, carbon black can be used. Alternatively, grafted carbon black can also be used. Examples of chromatic colorants include copper phthalocyanine, amide compounds of sulfone higher fatty acids or aromatic sulfonic acids, blue colorants such as derivative dyes, and yellow colorants such as benzidine derivatives collectively known as diazo yellow. and red coloring agents such as polytungstophosphoric acid, rhodamine B lake which is a double salt of molybdic acid and santhin dye, the azo pigment Chikaramin 6B, and quinacridone derivatives.

The binder contained in the core material of the capsule toner of the present invention disperses and holds the display recording material in the core material, and allows the visible image consisting of the display recording material formed on the latent image to be transferred to a paper-like material. It functions to fix the visible image on the support medium when it is transferred to the support medium.

Examples of binders that can be used in the present invention include:
The following high boiling point solvents having a boiling point of 180° C. or higher can be mentioned.

(1) Phthalate esters dibutyl phthalate, didecyl phthalate, diheptyl phthalate, dioctyl phthalate, dinonyl phthalate, didecyl phthalate, butyl phthalyl butyl glycolate, diptyl monochloro phthalate.

(2) Phosphate esters tricresyl phosphate, trioctyl phosphate, tris(isopropylphenyl) phosphate, tributyl phosphate, trihexyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, trioleyl phosphate, tris(butoxy) ethyl) phosphate, tris(chloroethyl) phosphate, tris(dichloropropyl) phosphate.

(3) Citric ugly esters O-acetyl triethyl citrate, 0-acetyl tributyl citrate, 0-7 cetyl trihexyl citrate, 0-acetyl trioctyl citrate, O-acetyl trinonyl citrate, O-acetyl tride Sil citrate, triethyl citrate, tributyl citrate, trihexyl citrate, trioctyl citrate,
Trinonyl citrate, tridecyl citrate.

(4) Benzoic acid esters butyl benzoate, hexyl benzoate, heptyl benzoate, octyl benzoate, nonyl benzoate, decyl benzoate, dodecyl benzoate, tridecyl benzoate, te, tradecyl benzoate,
Hexadecyl 7-benzoate, octadecyl benzoate, oleyl henschade, pentyl p-methylbenzoate, decyl p-methylbenzoate, octyl p-chloropenzoate, lauryl p-chlorobenzoate,
Propyl 2.4-dichlorobenzoate, octyl 2.
4-dichlorobenzoate, stearyl 2.4-dichlorobenzoate, oleyl 2.4-dichlorobenzoate, octyl p-methoxybenzoate.

(5) Fatty acid esters hexadecyl myristate, dibutoxyethyl succinate, dioctyl adipate, dioctyl azelate,
Decamethylene-1,10-diol diacetate, triacetin, tributin, benzyl cabrate, pentaerythritol tetracapronate, insorbite caprolate.

(6) Alkylnaphthalenes methylnaphthalene, dimethylnaphthalene, trimethylnaphthalene, monoisopro, bilnaphthalene, diisopropylnaphthalene, triisopropylnaphthalene, tetraisopropylnaphthalene, monomethyl, diethylnaphthalene, inoctylnaphthalene.

(7) Alkyldiphenyl ethers 0-methyldiphenyl ether, m-methyldiphenyl ether, p-methyldiphenyl ether.

(8) Amide compounds of higher fatty acids or aromatic sulfonic acids N,N-dimethyllauramide, N,N-diethylcaprylamide, N-butylbenzene sulfonamide.

(9) Trimellitic acid esters trioctyl trimellitate.

Further, examples of the above-mentioned high-boiling point solvents and other high-boiling point solvents that can be used in the present invention are described, for example, in the following patent publications.

Special Publication No. 48-23233, No. 49-29461:
JP-A-47-1031, JP-A No. 50-82632, JP-A No. 5
No. 0-82078, No. 51-2E1035, No. 51-
28 [No. 136, No. 51-28037, No. 51-27
No. 921, No. 51-27922: U.S. Patent No. 2,32
No. 2,027, No. 2,353,282, No. 2,5
No. 33,514, No. 2,835.5713, No. 2
, No. 852.383, No. 3.287,134, No. 3,554,755, No. 3,678,137, No. 3. [t? No. 8,142, No. 3700.454, No. 3.7411.141, No. 3,837.8E
IG No. 3,938,303: British Patent No. 958,441, British Patent No. 1,222,753
Issue: West German Open Gazette (OLS) No. 2,538.8H.

Particularly preferred high-boiling solvent type binders for use in the present invention are phthalate esters, phosphate esters, and alkylnaphthalenes.

Other examples of binders that can be used in the present invention include primary polymers.

Polyolefin, olefin copolymer, styrenic m
fat, methylene Φ butadiene copolymer, epoxy resin, polyester, rubber, polyvinylpyrrolidone, polyamide, coumaron/indene copolymer, methyl vinyl ether/maleic anhydride copolymer, maleic acid-modified phenol resin, phenol-modified terpene resin, silicone resin, epoxy-modified phenolic resin, natural resin-modified phenolic resin, amino resin, polyurethane, polyurea, homopolymer or copolymer of acrylic ester,
Homopolymers or copolymers of methacrylic acid esters, copolymers of acrylic acid and long-chain alkyl methacrylates, polyvinyl acetate, polyvinyl chloride.

Further, examples of the above-mentioned polymers and other polymers that can be used in the present invention are described, for example, in the following patent publications.

Special Publication No. 48-304911, No. 411-1588,
No. 54-8104: JP-A No. 48-75032, No. 48-78931, No. 49-17738, No. 51-132838, No. 52
-98531, 52-108134, 52-1
1H3? No. 53-1028, No. 53-38243
No. 53-118049, No. 55-89854,
No. 55-IHB55: U.S. Patent No. 3,893,933.

Particularly preferred polymeric binders for use in the present invention are homopolymers or copolymers of acrylic esters, homopolymers or copolymers of methacrylic esters, or styrene-butadiene copolymers.

In the present invention, the binder can be used alone or as a mixture on the tool.

The core material of the capsule toner of the present invention is composed of the binder, display/recording material, and hydrophobic silica as described above, but can contain various additives as desired. Examples of such additives include - cobalt for producing toners used in component development systems;
Examples include magnetic particles made of simple metals such as iron and nickel, alloys, or metal compounds.

The outer shell of the capsule toner of the present invention is made of a polymer or high-molecular substance, but if desired, this outer shell may also contain metal-containing dyes, charge control agents such as nigrosine, hydrophobic silica, etc. Glidants or other optional additives may be added. These additive substances can be incorporated into the outer shell of the capsule toner at any time, such as when the outer shell is formed or after the capsule toner is separated and dried.

After preparing the microcapsules by forming a shell around a core material containing hydrophobic silica, display-recording material and binder in a liquid medium, the microcapsules are separated from the liquid phase and dried. This separation and drying operation is usually carried out by spray drying a dispersion containing microcapsules.

In the present invention, it is desirable that the microcapsules separated and dried by the method described above are then subjected to heat treatment.This heat treatment further improves the powder properties of the capsule toner of the present invention. Heat treatment is 50-300℃
Preferably, the temperature is in the range of 80-
Particularly preferred is heating at a temperature in the range of 150°C.
The heating time varies depending on the heating temperature and the type of core material used, but is usually selected from the range of 10 minutes to 48 hours, and more generally from the range of 2 to 24 hours.

There are no particular restrictions on the equipment and instruments used for heat treatment, such as electric furnaces, Matsufuru furnaces, hot plates,
Any thermal drying equipment and appliances can be used, such as electric dryers, fluidized bed dryers, infrared dryers, etc.

Next, Examples and Comparative Examples of the present invention will be shown.

[Example 1 30 g of a dispersion of 5.0 g of cocarbon black and 2.5 g of hydrophobic silica dispersed in 22.5 g of dibutyl phthalate
A primary liquid was prepared by mixing 18 g of a mixed solvent consisting of 4 g of 1,4-naphthalidiol and 12 g of tetrahydrofuran.Next, 6 g of diphenylmethane-4,4'-diisocyanate and a catalyst were added to this secondary liquid. N of
- 0.05 g of ethylmorpholine was added at room temperature to prepare a secondary liquid.

Separately, gum arabic tg was dissolved in 1 ftg of water at 20°C, and while stirring the solution vigorously, the secondary liquid described in L was gradually poured into it, so that the average size of the oil droplets was 10 to 20.
An oil droplet type emulsion was obtained.

Note that this operation was performed while cooling the surroundings of the container so that the temperature of the emulsion did not exceed 30°C.

After emulsion formation is complete, reduce stirring and add 70%
°C warm water? Og was added and the temperature of the emulsion was then gradually increased to 80° C. over 10 minutes. The emulsion was maintained at this temperature for 30 minutes while stirring to complete the encapsulation, and then the microcapsule dispersion was centrifuged at 5000 rpm to separate the microcapsules and the gum arabic aqueous solution. A microcapsule slurry from which gum arabic was removed was obtained.

100 cc of water was added to this microcapsule slurry and dried in a spray dryer to obtain a powdered capsule toner.
Next, this capsule toner was subjected to heat treatment at 110° C. using an infrared dryer.

The capsule toner obtained above was evaluated by the following method.

A developer was prepared by thoroughly mixing 5 parts by weight of capsule toner and 95 parts by weight of iron powder carrier using a shaker. When the state of the capsule toner after mixing with the carrier was similarly observed under a microscope, no broken capsules were found.

Next, the electrostatic latent image formed by a conventional electrophotographic method was developed with the above developer to form a toner image, and the toner image was transferred to transfer paper to obtain a visible image. When this visible image was fixed under pressure using a pressure fixing roller at a pressure of 350 kg/cm', a copied image with good fixability and high sharpness was obtained. and.

Even when the surface of the copied image was rubbed with a finger, there was almost no change in the image. Also, using the same pressure fixing roller,
Although the copying operation was repeated 00 times, almost no toner adhered to the roller.

[Comparative Example 1] A capsule toner was obtained by carrying out the same operation as in Example 1 except that hydrophobic silica was not added during the production of microcapsules.

Using this capsule toner, the same procedure as in Example 1 was carried out.
When the copying operation was repeated 90 times, a copied image partially lacking in sharpness was obtained after 90 copies. Also, after the 90th copying operation, a phenomenon occurred in which some of the toner adhered to the roller.
At about the same time, a phenomenon was observed in which some of the toner adhering to the roller adhered to the transfer paper carrying the copied image, staining the transfer paper.

[Example 2] A primary liquid was prepared by dispersing 1 g of carbon black and 0.5 g of hydrophobic silica in 13 cc of tricresyl phosphate, and dissolving 1 g of toluylene diinocyanate 1 hexanetriol adduct therein. .

Separately, a secondary liquid was prepared by adding 7 g of polyvinyl alcohol to 100 cc of water. The primary liquid is added dropwise to the secondary liquid under stirring to form an emulsion in the form of microdroplets, and then at room temperature for about 2 hours, and then the liquid temperature is raised to -L to 80°C to form an emulsion for about 1 hour. was maintained.

- The toluylene diisocyanate/hexanetriol addition compound contained in the secondary liquid reacted with water to form a film around the microdroplets of the primary liquid. 100 cc of water was added to the thus obtained microcapsule slurry and spray-dried to obtain a powdered capsule toner. Next, this capsule toner was dried using an infrared dryer.
Heat treatment was performed at 10°C.

Next, copying operations were repeated 100 times using the same pressure fixing roller in the same manner as in Example 1 to check the offset properties of the capsule toner obtained above, but the toner hardly adhered to the roller. I didn't.

[Comparative Example 2] A capsule toner was obtained by carrying out the same operation as in Example 2 except that hydrophobic silica was not added during the production of microcapsules.

Using this capsule toner, the same procedure as in Example 1 was carried out.
When the copying operation was repeated 95 times, a copied image partially lacking in sharpness was obtained after 95 copies. Also, after the 95th copying operation, a phenomenon occurred in which some of the toner adhered to the roller.
At the same time, a phenomenon was observed in which some of the toner adhering to the roller adhered to the transfer paper carrying the copied image, staining the transfer paper.

Claims (1)

[Claims] 1. A capsule toner comprising a core material containing aqueous silica, a display/recording material, and a binder, and an outer shell formed around the core material. 2. The capsule toner according to claim 1, wherein the outer shell also contains 2° hydrophobic silica. 2. The capsule toner according to claim 1, wherein the outer shell formed around the 3° core material is made of polyurethane resin or polyurea resin. Claim 1, characterized in that the outer shell formed around the 4° core material is either a double wall made of a polyurea resin and a polyamide resin or a double wall made of a polyurethane resin and a polyamide resin. Capsule toner described in section.