JPH0547111B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a capsule toner used for converting a latent image formed in an electrophotographic recording method into a visible image. The present invention particularly relates to a capsule toner having excellent negative triboelectric charging properties. [Background of the Invention] Three types of methods are known for fixing toner images in recording methods such as electrophotography: heat fixing, solvent fixing, and pressure fixing. and,
Due to environmental concerns, heat fixing methods and pressure fixing methods that do not use solvents are often used these days. Toners formed by binding display recording materials with binders have been used in the heat fixing method. The same type of toner is also used in the pressure fixing method, but recently the use of capsule toner is being considered. Capsule toner is a toner in the form of microcapsules obtained by forming a resin shell that can be destroyed by applying pressure around a core material containing a display recording material such as carbon black and a binder. [Prior Art and Problems] Toner used as an electrophotographic developer is required to have good powder characteristics, excellent development performance, and not to stain the surface of the photoreceptor, which is the surface on which a latent image is formed. . In addition, the toner used in the pressure fixing method must have good pressure fixing properties, and the offset phenomenon to the pressure roller used for pressure fixing (a phenomenon in which the toner adheres to the pressure roller surface and stains it) is important.
It is necessary to make it difficult for this to occur. Therefore, the toner used in the pressure fixing method is required to have excellent properties in various aspects such as toner fluidity, storage stability, non-offset property, and chargeability depending on the developing method used. If some of them are inferior, the quality of the obtained visible image will deteriorate. Furthermore, toners with insulating surfaces have generally been used as developers for electrophotography, but recently toners with appropriate positive or negative triboelectric charging properties have been developed on the toner surfaces. ing. In other words, the toner used in electrophotography, in which the toner is charged by rubbing it against carrier particles such as iron powder or fur, and the charged toner is attracted to a latent image, may be positive or negative depending on the type of device. It is necessary to have negative or positive triboelectric chargeability corresponding to the chargeability of the latent image, which is defined as negative. Many resins have hitherto been known as outer shell materials for capsule toners, and it is also known that polyester resin is a resin having negative triboelectric charging properties. The present inventor studied a capsule toner having a polyester resin as an outer shell material as a capsule toner having negative triboelectric charging properties. However, according to research conducted by the present inventor, if an oil-based solvent is contained in the core material of a capsule toner made of polyester resin as the outer shell material, the oil-based solvent oozes out onto the toner surface through the outer shell during storage of the toner. Sometimes. When an oily solvent is present on the toner surface in a state of adhesion, aggregation among toner particles occurs significantly, making it difficult to maintain the fluidity of the toner. [Object of the Invention] An object of the present invention is to provide a novel electrophotographic capsule toner having negative triboelectric charging properties. A further object of the present invention is to provide an electrophotographic toner that has negative triboelectric charging properties and has improved fluidity and storage stability. [Summary of the Invention] The present invention comprises a core material containing a polymer, a high boiling point solvent with a boiling point of 150° C. or higher that can dissolve or swell the polymer, and a display/recording material, and an outer shell formed around the core material. In the capsule toner configured, the outer shell is made of a composite wall containing a polyurethane resin and/or polyurea resin and a polyester resin, and the polyol component constituting the resin is made of an aromatic polyol. It's in the toner. [Effects of the Invention] The capsule toner of the present invention has an outer shell that exhibits high negative triboelectrification, and also has excellent powder properties such as fluidity and storage stability, so that the images obtained are clear. , and there is little change in the visible image over time. Therefore, the capsule toner of the present invention is excellent as a developer for use in electrophotography. Furthermore, in the present invention, the triboelectrification of the capsule toner is achieved by varying the ratio of the polyester resin, which mainly contributes to imparting negative triboelectrification, and the polyurethane resin component or polyurea component, which mainly contributes to improving the denseness of the outer shell. It also has the advantage of being able to adjust gender. DETAILED DESCRIPTION OF THE INVENTION Capsule toners generally consist of a core material containing a binder and a display-recording material, and an outer shell formed around the core material. In the capsule toner of the present invention, a binder made of a polymer and an oily solvent is used as a binder. Among the components constituting the core material of the capsule toner of the present invention, there are no particular limitations on the polymer used as the binder component. 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 resin, polyurethane, polyurea,
Examples include homopolymers or copolymers of acrylic acid esters, homopolymers or copolymers of methacrylic acid esters, copolymer oligomers of acrylic acid and long-chain alkyl methacrylates, polyvinyl acetate, and polyvinyl chloride. Alternatively, they can be used in combination. Particularly preferred polymers for the binder are homopolymers or copolymers of acrylic esters, homopolymers or copolymers of methacrylic esters, or styrene-butadiene copolymers. As the oily solvent used as a component of the binder, a high boiling point solvent (hereinafter also simply referred to as a high boiling point solvent) with a boiling point of 150° C. or higher that can dissolve or swell the above-mentioned polymer is used. Examples of high-boiling solvents include phthalate esters (e.g., diethyl phthalate, dibutyl phthalate); aliphatic dicarboxylic acid esters (e.g., diethyl malonate, dimethyl oxalate); phosphate esters (e.g., tricresyl phosphate, tricylelyl phosphate); citric acid esters (e.g., o-acetyl triethyl citrate, tributyl citrate); benzoic acid esters (e.g.,
butyl benzoate, hexyl benzoate);
Fatty acid esters (e.g., hexadecyl myristate, dioctyl adipate); Alkylnaphthalenes (e.g., methylnaphthalene, dimethylnaphthalene, monoisopropylnaphthalene, diisopropylnaphthalene); Alkyl diphenyl ethers (e.g., o-, m-, p- -Methyl diphenyl ether); Amide compounds of higher fatty acids or aromatic sulfonic acids (e.g., N,N-dimethyllauramide, N-butylbenzenesulfonamide); Trimellitic acid esters (e.g., trioctyl trimellitate) and diarylalkane (e.g., diarylmethane such as dimethylphenylphenylmethane, diarylethane such as 1-phenyl-1-methylphenylethane, 1-dimethylphenyl-1-phenylethane, 1-ethylphenyl-1-phenylethane) ), etc. Note that the binder has a boiling point of 100 to 250 without substantially dissolving or swelling the above polymer.
An organic solvent within the temperature range (hereinafter also simply referred to as a low boiling point solvent) is used in combination. Examples of low boiling point solvents include aliphatic saturated hydrocarbons or organic liquid mixtures containing aliphatic saturated hydrocarbons as a main component. Preferably, the binder is a composition comprising a polymer, a high-boiling solvent, and a low-boiling solvent. Black toners such as carbon black and grafted carbon black are generally used as display and recording materials for electrophotographic toners, but various chromatic colorants such as blue, red, and yellow are also used. It is being The capsule toner of the present invention can also use these known display and recording materials as display and recording materials. The core material of the capsule toner of the present invention 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 a single metal such as cobalt, iron, or nickel, an alloy, or a metal compound. In addition,
When colored magnetic particles such as black magnetite are used as the magnetic particles, the colored magnetic particles such as magnetite can also be used as a component that serves as both the magnetic particles and the colored material. The outer shell of the capsule toner of the present invention includes a composite wall containing a polyurethane resin and/or a polyurea resin and a polyester resin, for example, a composite wall containing a polyurea resin and a polyester resin, a composite wall containing a polyurethane resin and a polyester resin,
Alternatively, it is a composite wall containing a polyurea resin, a polyurethane resin, and a polyester resin, and is further characterized in that an aromatic polyol is used as a polyol component constituting the resin. The outer shell made of a composite wall containing polyurethane resin and/or polyurea resin and polyester resin of the present invention has negative triboelectric charging properties and is particularly dense, and is therefore positively charged. The capsule toner has excellent fluidity and storage stability because it is easily adsorbed to the latent image, and the oily solvent in the core material hardly oozes out through the outer shell during storage of the capsule toner. The weight ratio of polyurethane resin and/or polyurea resin and polyester resin contained in the outer shell of the capsule toner of the present invention is 10:0.2 to 10:10.
It is preferably in the range of 10:0.5~
A ratio of 10:5 is particularly preferred. Such composite-walled shells are particularly suitable for forming capsule toners containing magnetic particles within the core material. Next, a method for manufacturing the capsule toner of the present invention will be explained. The capsule toner of the present invention is produced by dispersing a core material containing a display recording material and a binder (and optionally magnetic particles, etc.) in an aqueous medium in the form of oil droplets, and then dispersing a polyurethane resin and/or polyurea resin around the core material. A composite wall containing resin and polyester resin is formed and manufactured. As a method for manufacturing microcapsules using a polymerization reaction that can be used for manufacturing a capsule toner, known manufacturing methods such as an interfacial polymerization method, an internal polymerization method, and an external polymerization method can be mentioned. The composite wall containing the polyurethane resin and/or polyurea resin of the present invention and the polyester resin can be produced, for example, by the interfacial polymerization method described below. A composite wall containing a polyurethane resin and a polyester resin is prepared, for example, by an interfacial polymerization method using a polyisocyanate, an acid chloride, and an aromatic polyol, which involves adjusting the pH of an emulsifying medium that serves as a reaction solution, and then heating it. be able to. A composite wall containing a polyurea resin and a polyester resin can be prepared by using a polyisocyanate, an acid chloride, a polyamine, and an aromatic polyol, adjusting the pH of the emulsifying medium used as the reaction solution, and then heating it. A composite wall containing polyurea resin, polyurethane resin, and polyester resin is made of polyisocyanate, acid chloride, and polyamine and aromatic polyol (provided that the total molar amount of polyamine and polyol is approximately the same as the molar amount of polyisocyanate). ) to adjust the pH of the emulsifying medium that will become the reaction solution.
It can be prepared by subsequently heating. During the reaction for forming the outer shell, it is preferable to carry out the reaction for forming the outer shell while removing the organic solvent contained in the reaction system. Examples of specific compounds of polyisocyanates used to produce composite walls containing the above polyurethane resins and/or polyurea resins and polyester resins include diisocyanates (e.g., 2,4-tolylene diisocyanates) Nath,
2,6-tolylene diisocyanate, naphthalene-1,4-diisocyanate), triisocyanate (e.g., polymethylene polyphenyl isocyanate), tetraisocyanate (e.g., 4,4'-dimethyldiphenylmethane- 2) Compounds containing isocyanate groups such as polyisocyanate prepolymers (eg, adducts of tolylene diisocyanate and trimethylolpropane) can be mentioned. Examples of specific acid chloride compounds include:
Adipoyl chloride, sebacoyl chloride,
Phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, fumaroyl chloride, 1,4-cyclohexane dicarbonyl chloride, 4,4'-biphenyl dicarbonyl chloride, phosgene, 4,4'-sulfonyl dibenzoyl chloride, Mention may be made of succinoyl chloride, hydroquinone diacetyl chloride, oxaloyl chloride, polyesters with acid chloride functions, polyamides with acid chloride functions. Examples of specific polyamine compounds include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine,
p-phenylenediamine, m-phenylenediamine, 2-hydroxytrimethylenediamine, diethylenetriamine, triethylenetetraamine,
Examples include diethylaminopropylamine, tetraethylenepentamine, and adducts of epoxy compounds and amines. Examples of specific polyol compounds include hydroquinone, resorcinol, bisphenol A, 4
- Alkaline salt of chlorresorcin, alkaline salt of 2,2'-bis(4-hydroxyphenyl)propane, alkaline salt of 1,5-dihydroxynaphthalene, alkaline salt of phenolphthalene, alkaline salt of phenol formaldehyde initial condensate. ,
Alkaline salt of 4,4'-dihydroxydiphenylsulfone, alkali salt of 2,4-dihydroxybenzophenone, alkali salt of 4,4'-dihydroxybenzophenone, alkali salt of 2,4-dihydroxybenzaldehyde, melamine. Formaldehyde initial condensates can be mentioned. The microcapsules with the outer shell formed are then washed with water. The microcapsules 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 or heating and drying a slurry containing microcapsules. 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 at a temperature in the range of 80 to 150°C. The heating time can be appropriately determined depending on the heating temperature and the type of core material used, but is preferably heated for 2 to 24 hours. There are no particular limitations on the equipment and equipment used for the heat treatment, and examples of equipment include electric furnaces, muffle furnaces, hot plates, electric dryers, fluidized bed dryers, infrared dryers, and the like. If desired, metal-containing dyes, charge control agents such as nigrosine, or other arbitrary additives can be added to the outer shell of the capsule toner of the present invention. 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. Next, Examples and Comparative Examples of the present invention will be shown. still,
In Examples and Comparative Examples, "%" means "% by weight" unless otherwise specified. Example 1 50 g of magnetite magnetic particles were kneaded in a mortar into 50 g of a diphenylethane solution containing 50% by weight of polyisobutyl methacrylate (trade name Acrybase, MM-2002-1: manufactured by Fujikura Kasei Co., Ltd.) to form a black magnetic ink. was prepared. Terephthalic acid dichloride in 40g of ethyl acetate
After adding 1.0 g and 11.0 g of Burnock D750 (trade name: trimethylolpropane adduct of tolylene diisocyanate, manufactured by Dainippon Ink Chemical Industries, Ltd.) to make a homogeneous solution, the mixture was mixed with the black magnetic ink. It was made into an oily liquid. Separately, methyl cellulose 6
Prepare an aqueous solution by dissolving 1.5 g of 1.0 g in 194 g of water, add 1 g of bisphenol A, and adjust the pH using sodium carbonate.
was adjusted to 9.5 to obtain an aqueous solution. The resulting aqueous liquid
The above oily liquid was added while maintaining the temperature at 20°C and stirring vigorously to obtain an O/W type emulsion. After adjusting the average particle size of this emulsion to 10 μm, it was held for 10 minutes, 50 g of a 2.5% aqueous solution of diethylenetriamine was added, and this mixture was heated to 60 μm.
The encapsulation reaction was allowed to proceed by heating to ℃ for 2 hours. After the reaction was completed, decantation was performed to remove the supernatant liquid to obtain a capsule slurry. Methyl cellulose and salts were removed by repeating a water washing operation in which water was added to the slurry, stirred, and then decanted at the same time. After repeating this water washing operation 20 times, the capsule slurry was dried in an oven at 100°C, resulting in a smooth powdered capsule toner consisting of a composite wall containing polyurethane resin, polyurea resin, and polyester resin (polyurethane resin + polyurea resin: polyester resin). Resin=approximately 10:1, weight ratio) was obtained. The obtained capsule toner was a highly fluid powder with almost no aggregation observed even after long-term storage. When the above capsule toner was used as a one-component toner and a magnetic brush was formed on a magnetic roll, a uniform magnetic brush was formed. When the surface potential was measured, it was found to be negatively charged (minus 20 volts). Xerox 2000 using this magnetic brush
(manufactured by Fuji Xerox Co., Ltd.) After developing the positive electrostatic latent image, the formed toner image was transferred to paper and fixed under pressure of 250 kg/cm ² . After the above development, no toner remained on the photoreceptor, and it was confirmed that the transferability was good. Furthermore, the toner image fixed on the paper showed high sharpness and the toner image had excellent storage stability. Comparative Example 1 The same method as in Example 1 was used except that terephthalic acid dichloride and bisphenol A were not used, and the pH was not adjusted with sodium carbonate, from an outer shell containing a polyurea resin in the form of a smooth powder. I got a capsule toner. When this capsule toner was developed and transferred under optimal conditions in the same manner as in Example 1, some residual toner images were observed on the photoreceptor. Comparative Example 2 An oily liquid was prepared in the same manner as in Example 1 except that 10 g of terephthalic acid dichloride was used instead of Burnock D-750. Then bisphenol
An aqueous liquid was prepared using 10 g of A in the same manner as in Example 1, and a capsule toner having an outer shell containing a polyester resin was obtained in the same manner as in Example 1 without adding diethylenetriamine. The obtained toner contained many aggregates and had poor fluidity, making development and transfer difficult. Comparative Example 3 Polyisobutyl methacrylate (trade name: Acrybase, MM-2002-1: manufactured by Fujikura Kasei Co., Ltd.) at 50%
A black magnetic ink was prepared by kneading 50 g of magnetite magnetic particles in a mortar with 50 g of a solution of diphenylethane containing % by weight. Add 40g of ethyl acetate to Burnock D750 (product name:
Trimethylolpropane adduct of tolylene diisocyanate (manufactured by Dainippon Ink & Chemicals Co., Ltd.) 12.0g
and Epicote 828 (product name: liquid bisphenol A type epoxy resin, manufactured by Ciel Epoxy Co., Ltd.) 2.0
After adding g to make a uniform solution, it was mixed with the black magnetic ink to make an oil-based liquid. The following is Example 1
A capsule toner consisting of an outer shell containing a polyurethane resin was obtained in the same manner as described above. The obtained toner was a smooth and highly fluid powder, and a uniform magnetic brush was formed on a magnetic roll for one-component toner. Furthermore, the electrostatic latent image formed by Xerox 2000 was developed using this magnetic brush. The resulting image had a slightly low density, and some toner image remained on the photoreceptor. Comparative Example 4 A capsule toner was obtained in the same manner as in Example 1 except that ethylene glycol was used instead of bisphenol A. The obtained toner was a smooth and highly fluid powder, and a uniform magnetic brush was formed on a magnetic roll for one-component toner. Furthermore, the electrostatic latent image formed by Xerox 2000 was developed using this magnetic brush. The resulting image had a slightly low density, and some toner image remained on the photoreceptor. Furthermore, storage stability at high temperatures was evaluated as described below. [Storage Stability at High Temperatures] The storage stability (storage stability of the oily substance in the core material) of the capsule toners obtained in Example 1 and Comparative Examples 1 to 4 was evaluated by the following method. As a measurement sample, 1 g of capsule toner powder was taken and stored in an oven maintained at 100° C. for 16 hours and 48 hours, and then the remaining amount of oily substance in the core substance of the capsule toner was measured. The results obtained are shown in Table 1. In Table 1, the remaining amount of the oily substance is expressed as the weight % of the amount of the oily substance remaining after storage for a predetermined time relative to the amount of oily substance before storage under heat. 【table】

Claims (1)

[Scope of Claims] 1. Consisting of a core material containing a polymer, a high boiling point solvent with a boiling point of 150°C or higher that can dissolve or swell the polymer, and a display/recording material, and an outer shell formed around the core material. A capsule toner characterized in that the outer shell is made of a composite wall containing a polyurethane resin and/or a polyurea resin and a polyester resin, and the polyol component constituting the resin is made of an aromatic polyol. 2. The capsule toner according to claim 1, wherein the weight ratio of polyurethane resin and/or polyurea resin to polyester resin contained in the outer shell is in the range of 10:0.2 to 10:10. . 3. The capsule toner according to claim 1, wherein the outer shell is made of a composite wall containing a polyurethane resin and a polyester resin. 4. The capsule toner according to claim 1, wherein the outer shell is made of a composite wall containing a polyurea resin and a polyester resin. 5. The capsule toner according to claim 1, wherein the outer shell is made of a composite wall containing a polyurethane resin, a polyurea resin, and a polyester resin.