JPS6088959A - Production of insulating capsule toner - Google Patents

Abstract

PURPOSE:To obtain an insulating capsule toner having high electrical resistance by removing the ion material sticking to the surface of the capsule toner in the stage for manufacturing the capsule toner used for electrophotography. CONSTITUTION:The microcapsule formed in an aq. liquid is separated in the form of a slurry material by a method such as centrifugal sepn. and the slurry is dispersed in demineralized water or distilled water, by which the slurry is preliminarily cleaned. The microcapsule is separated from the cleaning water. The slurry is dispersed in water contg. an ion exchange resin to clean the microcapsule. The cleaning is preferably accomplished in a way as to remove both anion and cation sticking to the microscapsule and therefore combination use of the cation exchange resin and anion exchange resin is preferable. The dried capsule toner exhibits high electrical resistance as ionic impurities in particular are less stuck thereto and therefore the capsule toner has an excellent characteristics for electrophotography for which triboelectrification is used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a capsule toner used for converting a latent image formed in a recording method such as electrophotography into a visible image. The present invention relates to a method for producing an insulating capsule toner having the following properties.

Three types of methods are known for fixing toner images in recording methods such as electrophotography: heat fixing, solvent fixing, and pressure fixing. Among these methods, the pressure fixing method does not use heat or solvent, so it does not suffer from the various problems associated with methods such as heat fixing or solvent fixing, and has a fast access time, making it possible to follow high-speed fixed methods. It inherently has various advantages in certain respects. The present invention provides a method for producing a capsule toner suitable for the pressure fixing method in this category.

While the pressure fixing method has many advantages as mentioned above, it has poor fixing properties compared to fixing methods such as heat fixing, the fixed image is easily peeled off when rubbed, and it requires considerably high pressure for fixing. Therefore, fatigue of the support medium such as transfer paper is likely to occur due to destruction of m fibers, the surface of the support medium is likely to become excessively glossy, and high pressure is applied. Since there is a limit to the miniaturization of the pressure roller, there is a problem in that there is a limit to the 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 toners contain colored materials such as carbon black and polymers,
It is a toner in the form of microcapsules obtained by forming an outer shell that can be destroyed by applying pressure around a core material containing a paint such as a high-boiling solvent. Capsule toner is said to be a toner suitable for pressure fixing because it does not require high pressure for fixing and has excellent fixing properties. It cannot be said that the various properties that are originally needed are necessarily satisfactory. In other words, the toner used as an electrophotographic developer must have good powder characteristics, excellent developing performance, and do not stain the surface of the photoreceptor, which is the surface on which the latent image is formed. The toner used in this method must have good pressure fixing properties and be resistant to the offset phenomenon (a phenomenon in which toner adheres to the pressure roller surface and stains it) on the pressure roller used for pressure fixing. . In other words, the toner used in the pressure fixing method has powder properties, fixability to support media such as paper (including the shelf life of the fixed image), non-offset properties, and chargeability depending on the developing method used. All properties such as electrical resistance (or conductivity) must be at a high level. ′
However, the capsule toners known so far have not always been satisfactory for the above-mentioned properties.

Among these objects, the present invention provides, among other things, a method for producing an insulating capsule toner having increased electrical resistance. In other words, typical methods for charging capsule toner include a method in which the capsule toner is mixed with a carrier such as iron powder to generate triboelectrification, and a method in which the capsule toner is charged by rubbing it against a material such as fur. There are known methods to do this. The capsule toner used in this method of charging using frictional charging must be an insulating capsule toner with high electrical resistance in order to achieve efficient charging and maintain the charge stably. There is. In other words, when the above-mentioned frictional charging is performed using capsule toner with poor electrical resistance, the charging does not occur smoothly and the charging tends to leak out in a short period of time, making it difficult to perform development properly. This may cause problems such as difficulty in moving.

The present invention explains that the reason why it is difficult for the electrical resistance of the capsule toner to reach a sufficiently high level is that various impurities, especially ionic substances, that adhere to the surface of the capsule toner during the production process of the capsule toner reduce the electrical resistance of the toner. Furthermore, such impurities can be efficiently removed by washing the capsule toner with water containing ion exchange resin, and this washing operation can reduce the high electrical resistance. The present invention was accomplished by discovering that an insulating capsule toner having the following properties can be obtained.

Fish” with J! j Therefore, the present invention provides a coloring material dispersed in an aqueous liquid and/or
In a method for manufacturing a capsule toner, which comprises forming an outer shell around an oil droplet-like core material containing a primary shell to form microcapsules, and separating and drying the microcapsules, before drying the microcapsules. Another object of the present invention is to provide a method for producing an insulating capsule toner, which comprises washing microcapsules with water in the presence of an ion exchange resin.

- colored materials such as carbon black, and polymers,
A core material containing a binder such as a high-boiling point solvent is dispersed in the form of oil droplets in an aqueous liquid such as water, and then an outer shell that has the property of breaking when pressure is applied is placed around the oil droplet-like core material. As mentioned above, a method for manufacturing a capsule toner is already known, which consists of forming microcapsules, and then separating the microcapsules from an aqueous liquid and drying them.

There are no particular limitations on the composition of the core material, the material of the outer shell, and the method for manufacturing microcapsules that can be used in carrying out the method for manufacturing the capsule toner of the present invention. For example, various known materials and methods for manufacturing microcapsules may be used. can do.

However, as the binder, it is desirable to use a binder composition containing a polymer and a high boiling point solvent that can dissolve or swell the polymer.

Examples of polymers include polyolefins, olefin copolymers, styrene resins, styrene-butadiene copolymers, epoxy resins, polyesters, rubbers, polyvinylpyrrolidone, polyamides, coumaron-indene copolymers, methyl vinyl ether-maleic anhydride copolymers. , amino resins, polyurethanes, polyureas, homopolymers or copolymers of acrylic esters, homopolymers or copolymers of methacrylic esters, copolymer oligomers of acrylic acid and long-chain alkyl methacrylates, polyvinyl acetate, polyvinyl chloride. I can do it.

Particularly preferred among these polymers are homopolymers or copolymers of acrylic esters, homopolymers or copolymers of methacrylic esters, or styrene-butadiene copolymers.

Examples of high-boiling solvents that can dissolve or swell the above-mentioned polymers include fucuric acid esters such as dibutyl fucurate; aliphatic dicarboxylic acid esters such as diethyl malonate; and tricresyl phosphate. phosphoric acid esters such as citrate; enoic acid esters such as 0-acetyltriethyl citrate; and benzoic acid esters such as butyl benzoate.

Aroma esters; Fatty acid esters such as dioctyl adipate; Alkylnaphthalenes such as methylnaphthalene: Alkyldiphenyl ethers such as 0-methyldiphenyl ether; N,N-dimethyllauramide, N-butylbenzenesulfonamide Mention may be made of amide compounds of higher fatty acids or aromatic sulfonic acids such as; trimellitic acid esters such as trioctyl trimellitate; and diarylalkanes such as l-isopropyl-phenyl-2-phenylmethane.

Particularly preferred among the high boiling point solvents mentioned above are phthalic acid esters, aliphatic dicarboxylic acid esters, alkylnaphthalenes and diarylalkane. ``Black toners such as carbon black and grafted carbon black are commonly used as coloring materials for electrophotographic toners, but various chromatic colorants such as blue, red, and yellow are also used. It is being These known coloring materials can also be used in producing the capsule toner of the present invention.

The core material of the capsule toner may contain magnetic particles. As the magnetic particles, known magnetic particles (magnetizable particulate matter) for magnetic toner can be used. Examples of such magnetic particles include magnetic particles made of elemental metals, alloys, or metal compounds such as cobalt, iron, or nickel. Note that when colored magnetic particles such as black magnetite are used as the magnetic particles, the superchromic magnetic particles such as magnetite can also be used as a component that serves as both the magnetic particles and the colored material.

Note that the capsule toner may contain various additives, for example, a release agent such as a fluororesin, if desired.

A method for manufacturing microcapsules is already known in which an outer shell made of a polymeric material is formed around a core material dispersed in the form of oil droplets containing magnetic particles, a coloring material, and a binder in an aqueous liquid. , these known methods can also be used to produce the capsule toner of the present invention.

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

Other examples of methods for producing microcapsules that can be used in undeveloped IJ11 include an internal injection method, a phase separation method, an external polymerization method, a melt dispersion cooling method, and a coacervation method.

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.

The polymer material forming the outer shell is not particularly limited, but examples include polyurethane resin, polyamide resin, polyester resin, polysulfonamide resin, polyurea resin, epoxy resin, polysulfanate resin, and polycarbonate resin. . The outer shell made of these resins can be easily formed by a known interfacial polymerization method.

Among these polymeric substances, preferred are polyurea resins and polyurethane resins, which include polyincyanates such as diisocyanates, triisocyanates, tetraisocyanates, and polyisocyanate prepolymers, diamines, triamines, The outer shell of microcapsules can be easily formed by reacting a polyamine such as tetraamine, a prepolymer containing two amino groups, piperazine and its derivatives, a polyol, etc. in an aqueous solvent by an interfacial polymerization method.

In addition to the polymer materials mentioned above, examples of the outer shell material include melamine resins, urea resins, polymers of styrene or substituted products thereof, and copolymers thereof (e.g., polystyrene, polyparachlorostyrene). , styrene/butadiene copolymer, styrene/acrylic acid copolymer, styrene/acrylic acid ester copolymer, styrene/methacrylic acid copolymer, styrene/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 resin,
Polyvinyl alcohol resins, polyvinylpyrrolidone, and the like can also be used.

Further, it is particularly preferable that the outer shell of the capsule toner is a composite wall formed from various polymeric materials. It is particularly desirable to use jtrz Uki 11 in the present invention [
j-to first ell^--=de L to Into 1-J+1-
++Auto-lt ■-・-A composite wall, and a composite wall consisting of polyurethane resin and polyamide resin. Alternatively, it may be a composite wall made of polyurea resin, polyurethane resin, and polyamide resin.

Composite walls made of polyurethane resin and polyamide resin,
For example, it can be prepared by an interfacial polymerization method using polyisocyanate, acid chloride, polyamine and polyol, adjusting the pH of an emulsifying medium serving as a reaction liquid, and then heating. In addition, a composite wall made of polyurea resin and polyamide resin can be produced by using polyisocyanate, acid chloride, and polyamine, adjusting the pH of the emulsifying medium that becomes the reaction liquid, and then heating it.
Can be made around the clock. Details of the manufacturing method of these composite walls made of polyurea resin and polyamide resin and composite walls made of polyurethane resin and polyamide resin are described in the specification of Japanese Patent Application No. 165262/1982. Such a composite-walled shell is particularly suitable for forming magnetic capsule toners of the form W containing magnetic particles in the core material.

When forming a composite wall containing polyamide resin as mentioned above, it is generally necessary to
Although a sub-adjustment step is inserted, when cations such as alkali metal ions introduced into the microcapsule manufacturing reaction system adhere to the surface of the capsule toner, the electrical resistance of the toner is significantly reduced. Therefore, the method for producing a capsule toner of the present invention is a composite wall containing magnetic particles in the core material and a polyamide resin in the outer shell, such as a polyurea resin/polyamide resin composite wall.

It is particularly advantageous when used in the production of a capsule toner having a polyurethane resin/polyamide resin composite wall ψ polyurea resin/polyurethane resin/polyamide resin composite wall.

Microcapsules produced by forming an outer shell around a core material in an aqueous liquid are then separated from the liquid phase and dried. This separation and drying operation is usually carried out by spray drying a dispersion containing microcapsules.

The method for producing a capsule toner of the present invention is characterized in that, before drying the microcapsules formed in an aqueous liquid, the microcapsules are washed with water containing an ion exchange resin. The microcapsules according to the present invention are preferably washed, for example, by the following operation.

First, microcapsules formed in an aqueous liquid are separated into an aqueous liquid (reaction medium) by a method such as centrifugation.
The slurry is then separated into a slurry and then pre-washed by dispersing it in water (preferably ion-exchanged water or distilled water). Microcapsules are then separated from this wash water. It is desirable that such a pre-4J11 washing step for microcapsules be repeated, for example, 5 or more times, preferably 10 or more times.

Next, the microcapsule slurry is dispersed in water containing an ion exchange resin (preferably ion exchange water or distilled water) to wash the microcapsules.
This washing step using water containing an ion exchange resin may be performed only once, or may be performed repeatedly.

The ion exchange resin used in the present invention is not particularly limited, and known cation exchange resins and anion exchange resins can be used. However, in the microcapsule cleaning step according to the present invention, it is desirable to remove both anions and cations attached to the microcapsules, so it is preferable to use both a cation exchange resin and an anion exchange resin. . Further, since the attachment of cations such as alkali metal ions tends to lower the electrical resistance of the capsule toner, it is advantageous to use a cation exchange resin when only one type of ion exchange resin is used.

The microcapsules washed according to the invention are then dried by known methods.

The capsule toner produced as described above exhibits high electrical resistance due to less adhesion of impurities, particularly ionic impurities, to its surface, and thus exhibits triboelectric properties.

Note that it is desirable that the separated and dried microcapsules be further subjected to heat treatment. This heat treatment particularly improves the powder properties of the capsule toner.

The heat treatment is preferably carried out at a temperature in the range of 50 to 300°C, and particularly preferably in the range of 80 to 150°C. The heating time varies depending on the heating temperature and the type of core material used, but is usually selected from 10 minutes to 48 hours, and more generally from 2 to 48 hours.
Selected from a 24 hour range.

There are no particular restrictions on the equipment and equipment used for heat treatment; for example, any heating drying equipment and heating drying such as an electric furnace, matzuru furnace, hot plate, electric dryer, fluidized bed dryer, infrared dryer, etc. Instruments can be used.

The outer shell of the Naori Pcel toner may optionally contain metal-containing dyes, charge control agents such as nigrosine, fluidizing agents such as hydrophobic silica, or other additives. I can do it. 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.

Furthermore, when carrying out the method for manufacturing the capsule toner of the present invention, Japanese Patent Application Laid-Open No. 57-179860.58-21259.58-
66948.58-66949.58-66950.5
8-68753.58-70236.58-91464
．． 58-95353.58-100855.58-10
0856.58-100857.58-100858.
58-1l1050.58-144932.58-14
Publications No. 5233 and Japanese Patent Application No. 57-64673.57-175404.57-
189139.58-41960.58-48418.
58-58419.58-57421.58-5742
It is also possible to use it in appropriate combination with the capsule toner and capsule toner manufacturing technology described in patent application No. 2.58-174895.

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

[Example 1] 501ffi of polyisobutyl methacrylate (trade name Niacrybase, MM-2002-2: manufactured by Fujikura Kasei ■)
% of l-isopropyl-phenyl-2-phenylethane (trade name: CPE, manufactured by Kureha Chemical Foundation) and magnetite magnetic particles (trade name: EPT-1).
A dispersion liquid (magnetic ink) was prepared by cross-dispersing 50 g of 000 (manufactured by Toda Kogyo ■) in an automatic mortar.

Separately, 2.2 g of terephthalic acid chloride in 20 g of ethyl acetate.
A solution was prepared in which 9.9 g of an addition compound of toluylene diisocyanate and trimethylolpropane (trade name: Parnock D-750, manufactured by Dainippon Ink & Chemicals) was dissolved, and this solution was mixed with the above dispersion. did. Next, add this mixture to methylcellulose (product name: Metrozeu 60S).
H: Emulsified and dispersed in 200 g of a 5% aqueous solution (manufactured by Shin-Etsu Chemical Co., Ltd.). After adjusting the average size of oil droplets in the emulsion to about 13 gm, about 10 minutes later, diethylenetriamine
．． The pH was adjusted to 11.0 by adding 50 g of a 5% aqueous solution and then a 5% aqueous solution of sodium carbonate. This emulsion was stirred in a constant temperature bath at 65° C. for about 3 hours to complete encapsulation.

The obtained microcapsule dispersion was centrifuged to precipitate the microcapsules, and the supernatant liquid was replaced with distilled water. The microcapsules were redispersed in this distilled water, and the microcapsules were similarly washed by centrifugation and replacing the supernatant with distilled water. This cleaning operation is performed 2 times.
After 0 times, distilled water (cation exchange resin) containing cation exchange resin (product name: DOWEX 50W: manufactured by Dow Chemical Company) and anion exchange resin (product name: DOWEX 1: manufactured by Dow Chemical Company) Disperse the microcapsules in 1/10 of the solid weight of the microcapsules, and use approximately 20 times more water than the solid molecule fui of the microcapsules, wash with water, and remove the ion exchange resin by filtration. Thereafter, the microcapsule slurry was dried in an open air at 100° C. for 5 hours to obtain a powdered capsule toner.

The electrical resistance of the obtained powder capsule toner was 28°C.
Under the conditions of 185%RH, 1X10'V/cm -t' 7
X 10”Ω@Cm.

The capsule toner described above is a very smooth and highly fluid powder, and microscopic observation confirmed that most of the capsule particles existed independently.

An electrostatic latent image formed by ordinary electrophotography was developed with the above capsule toner to form a toner image, and then 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/crn', a copy image with high sharpness was obtained.

[Comparative Example 1] A powdered capsule toner was obtained by carrying out the operation described in Example 1, except that the washing step using distilled water containing an ion exchange resin was replaced with a washing step using only distilled water.

The electrical resistance of the obtained powder capsule toner was as shown in Example 1.
Example 2 20 washing steps of the microcapsules separated from the aqueous reaction medium were carried out with well water and a washing step with distilled water containing ion exchange resin. A powdered capsule toner was obtained by carrying out the operation described in Example 1, except that the washing step was replaced with a washing step using well water using the same amount of ion exchange resin.

The electrical resistance of the obtained powder capsule toner was 28°C;
5X under conditions of 85% RH, 1XlO'V/am
I O”Ω·cm.

The capsule toner described above is a very smooth and highly fluid powder, and microscopic observation confirmed that most of the capsule particles existed independently.

When an electrophotographic operation was carried out using the above capsule toner according to the method described in Example 1, a copied image with high sharpness was obtained.

[Comparative Example 2] A powdered capsule toner was obtained by carrying out the same operation as in Example 2, except that the washing step using well water containing an ion exchange resin was replaced with a washing step using only well water.

The electrical resistance of the obtained powder capsule toner was as shown in Example 2.
Under the same conditions, l A powdered capsule toner was obtained by carrying out the operation described in Example 1, except that the washing step was replaced with a washing step using a cation exchange resin (using the same cation exchange resin).

The electrical resistance of the obtained powder capsule toner is:

3 under the conditions of 28°C, 85% RH1IX10'V/cm
, 5×10” Ωecm.

The capsule toner described above is a very smooth and highly fluid powder, and microscopic observation confirmed that most of the capsule particles existed independently.

When an electrophotographic operation was carried out by the method described in Example 1 using the capsule toner described above, a copied image with high sharpness was obtained.

Patent applicant: Fuji Photo F4' / Rem Co., Ltd. Agent
Patent attorney Yasuo Yanagawa

Claims (1)

[Claims] l. A method for producing a capsule toner comprising forming an outer shell around an oil droplet-like core material containing a coloring material and a binder dispersed in an aqueous liquid to form microcapsules, and then separating and drying the microcapsules. In,
A method for producing an insulating capsule toner, which comprises washing the microcapsules with water in the presence of an ion exchange resin before drying the microcapsules. 2. The method for producing an insulating capsule toner according to claim 1, characterized in that a cation exchange resin and an anion exchange resin are used in combination as the 2° ion exchange resin. 3. The method for producing an insulating capsule toner according to claim 1, wherein a cation exchange resin is used as the 3° ion exchange resin. 2. The method for producing an insulating capsule toner according to claim 1, wherein the 4° outer shell is made of a composite wall containing a polyurea resin and/or polyurethane resin and a polyamide resin. 2. The method for producing an insulating capsule toner according to claim 1, wherein the 5° core material contains magnetic particles.