JP5616941B2 - Toner and method for producing the same - Google Patents

Description

  The present invention relates to a toner in which fixing property, storage property and charging property are harmonized and a method for producing the same.

Along with energy saving in recent years, a toner that is fixed at a low temperature is required as a characteristic required for the toner. However, if a toner binder resin having a low glass transition temperature is selected in order to achieve low-temperature fixability, the storage stability of the toner inevitably deteriorates. In order to solve such problems, a method of encapsulating the toner surface with a resin having a high glass transition temperature or a resin having a crosslinked structure has been studied.
As typical toner encapsulation methods, there are a method in which resin particles are adhered and fused to the particle surface, and a method in which a polymerizable monomer is reacted on the particle surface.

  As a method for adhering and fusing resin particles to the particle surface, there is a method in which toner component particles are aggregated in water to form core particles, and fine particles for shells are adhered and coated thereon, and the fine particles are melted by heat. is there. Although this method has the possibility of achieving both low temperature fixability and storage stability by making the thermal properties of the shell particles higher than that of the core particles, it is formed in association with the shell particles being about 0.1 μm μm. There is a problem that the shell layer becomes thick and the low-temperature fixability deteriorates.

  On the other hand, as a method of reacting a polymerizable monomer on the particle surface, there is a method of coating a urea resin by an in situ polymerization method, and an extremely thin shell layer can be formed. However, since a low molecular weight monomer is used, a crosslinked structure is used. There is a problem that the density becomes low and the low-temperature fixability deteriorates. In addition, the charging performance as a toner tends to deteriorate, and there is also a safety problem due to the residual formaldehyde used as a monomer.

Japanese Patent No. 3141784 Japanese Patent No. 4204360

  SUMMARY OF THE INVENTION An object of the present invention is to provide a toner and a method for producing the same, which improve the above-mentioned problems and form a very thin shell layer to achieve both low-temperature fixability and storage stability and further control chargeability. To do.

In order to solve the above-described problems, the toner according to the embodiment of the present invention includes a water-soluble polymer-based crosslinking agent that crosslinks with a carboxyl group on a core particle containing at least a binder resin having a carboxyl group and a colorant, one sequential processing to have a resultant crosslinked coating layer, and the acidic pH adjusting agent is less carboxyl groups molecular weight than the water-soluble polymeric carboxylic acids by sex polymeric carboxylic acid and an acidic pH adjusting agent It consists of a combination of a water-soluble compound having water and a water-soluble compound having a plurality of carboxyl groups.
The toner manufacturing method according to the embodiment of the present invention includes, in an aqueous dispersion medium, first a core resin containing at least a binder resin having a carboxyl group and a colorant, and a water-soluble polymer-based crosslinking agent that undergoes a crosslinking reaction with the carboxyl group. Next, a water-soluble polymer carboxylic acid and an acidic pH adjuster that is a water-soluble compound having a carboxy group having a molecular weight lower than that of the water-soluble polymer carboxylic acid are sequentially added and mixed to form a crosslinking reaction. It is characterized by raising.

1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described sequentially. In the following description, “%” and “parts” representing the composition or component ratio are based on weight unless otherwise specified.
The toner according to the exemplary embodiment of the present invention is a capsule toner having a shell layer having a very thin, strong and flexible cross-linked structure. In the toner particles, a water-soluble crosslinking agent (layer) is a water-soluble polymer (hereinafter referred to as “water-soluble polymer”) having a carboxyl group by crosslinking reaction with a carboxyl group of particles containing a binder resin and a colorant as core components. It also has a cross-linking reaction with a “polymeric carboxylic acid”. Therefore, it is considered that a resin layer (shell layer) that is reacted with the crosslinking agent and the water-soluble polymer carboxylic acid is formed on the particle surface, and the resin layer is chemically bonded to the core component. Therefore, the obtained toner has a strong capsule structure capable of withstanding a mechanical load and a chemical load. In addition, this shell layer includes the acid value of the binder resin, the type of crosslinking agent, the amount of crosslinking agent added, the acid value of the polymeric carboxylic acid, the molecular weight of the polymeric carboxylic acid, the added amount of the polymeric carboxylic acid, the reaction The thickness can be adjusted by temperature. The thicker the shell layer, the better the storage stability. However, in order not to impair the toner fixing property, it is preferable to form the shell with a minimum thickness that can maintain the storage stability. The film thickness can be obtained by calculation from the radius of the core particles, the specific gravity of the core particles, the addition amount of the shell material, and the specific gravity of the shell material, and is preferably in the range of 0.2 nm to 20 nm.

(Manufacture of core particles)
In order to produce the toner of the embodiment of the present invention, first, core particles containing at least a binder resin having a carboxyl group and a colorant are prepared. Examples of the binder resin having a carboxyl group include styrene resins such as styrene / acrylic copolymers, polyester resins, acrylic resins, phenol resins, epoxy resins, allyl phthalate resins, polyamide resins, and maleic acid. Based resins. These resins may be used alone or in combination of two or more. The acid value (JIS K0070) of these resins is 5 to 50 mgKOH / g, desirably 10 to 30 mgKOH / g. Further, these resins preferably have a glass transition temperature of 30 to 80 ° C. and a softening point of 60 to 180 ° C. In particular, a polyester resin having good fixability is desirable.

  As a method for producing the core particles, any of known methods for producing toner particles such as a kneading and pulverizing method, a suspension polymerization method, an aggregation method, and a dissolution suspension method may be applied. Some of the preferred core particle production modes will be described later.

When the core particles (toner particles before capsule coating according to the embodiment of the present invention) are obtained in a dry state, the core particles are dispersed in an aqueous dispersion medium using a dispersant such as a surfactant. An aqueous dispersion is formed. The aqueous dispersion medium may be water only in many cases, but an appropriate amount of a water-miscible liquid such as alcohol or acetone may be mixed as necessary. In this case, if a water-soluble crosslinking agent is used for dispersion, a crosslinking reaction can be efficiently performed.
After the addition of the water-soluble polymer-based crosslinking agent, a water-soluble polymer-based carboxylic acid and an acidic pH adjuster are sequentially added and mixed to promote hydrogenation of the carboxylic acid hydrogen, thereby promoting the crosslinking reaction.

  On the other hand, in the case of core particles prepared by a wet method such as a suspension polymerization method, an agglomeration method, or a dissolution suspension method, a water-soluble polymer crosslinking agent is directly applied to an aqueous dispersion before washing and drying according to the embodiment of the present invention. Then, a water-soluble polymer carboxylic acid and an acidic pH adjuster can be sequentially added to cause a crosslinking reaction. Further, a water-soluble polymer crosslinking agent may be added during the preparation of the core particles.

More specifically, a water-soluble polymer-based crosslinking agent is added to the aqueous dispersion of the core particles obtained above, preferably while stirring at 30 to 95 ° C. with stirring, and then water-soluble. The polymeric carboxylic acid and the acidic pH adjuster are sequentially added in this order, preferably in the form of an aqueous solution, to cause a crosslinking reaction. However, in the embodiment of the present invention, the mixing of the core particles and the water-soluble polymer crosslinking agent in the aqueous dispersion medium is performed prior to the addition of the water-soluble polymer carboxylic acid and the acidic pH adjusting agent. Therefore, the order of adding the core particles and the water-soluble polymer-based crosslinking agent to the aqueous dispersion medium is arbitrary, and any of them may be added at the same time.
It is desirable to add the water-soluble polymer carboxylic acid after sufficiently reacting the water-soluble polymer crosslinking agent and the core particles. The reaction time between the cross-linking agent and the core particles varies depending on the temperature, but at least 0.5 to 12 hours are required. Further, after addition of the water-soluble polymer carboxylic acid and further after addition of the acidic pH adjuster, it is desirable to take 0.5 to 12 hours, although it varies depending on the reaction temperature.

  The core particle concentration in the aqueous dispersion at the time before addition of the water-soluble crosslinking agent or the like is 1 to 50%, desirably 10 to 40%. If it is less than 1%, the productivity is poor, and if it exceeds 50%, it is not in a slurry state and cannot be produced. The particle diameter of the core particles is 1 to 20 μm, desirably 3 to 15 μm. If it is less than 1 μm or exceeds 20 μm, handling as toner particles becomes difficult.

  The water-soluble crosslinking agent that undergoes a crosslinking reaction with a carboxy group is not limited as long as it is a water-soluble polymer compound that reacts with a carboxyl group. For example, an isocyanate crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a carbodiimide And the like, and the like. The molecular weight is preferably 1,000 to 1,000,000. From the viewpoint of safety and chargeability, a water-soluble polymer having an oxazoline group that is an oxazoline-based crosslinking agent and a water-soluble polymer having a carbodiimide group that is a carbodiimide-based crosslinking agent are desirable. Examples of commercially available products include Nisshinbo Chemical Co., Ltd., Carbodilite SV-02, V-02, V02-L2, V-04; Nippon Shokubai Co., Ltd., Epocross WS300, WS500, WS700.

  Subsequent to the crosslinking treatment by addition and mixing of the water-soluble crosslinking agent, the water-soluble polymer carboxylic acid and the acidic pH adjuster are sequentially added and mixed.

  As the water-soluble polymer carboxylic acid, any water-soluble polymer having a carboxyl group in the molecule may be used. For example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, aspartic acid, crotonic acid, itacone Examples thereof include polymers containing acid and citraconic acid as monomers, copolymers thereof, metal salts thereof, ammonium salts thereof, esterified products thereof, mixtures of these polymers, and the like. Among these, acrylic acid polymers (single or copolymer) are particularly suitable from the viewpoints of water solubility and coating film characteristics. The weight average molecular weight (weight average molecular weight in terms of polyethylene glycol by GPC) is preferably 1,000 to 1,000,000, and the acid value is preferably 10 to 10,000. Moreover, since a crosslinking reaction is inhibited when it is a metal salt or an ammonium salt, it is inappropriate to use a salt in which all the carboxyl groups are substituted. Generally, the pH during addition and mixing of the water-soluble polymer carboxylic acid is 1 to 9, preferably 2 to 7. The acidic pH adjuster further lowers the pH to 1-7, preferably 2-4, and promotes the crosslinking reaction as compared with the pass-through mixing of the water-soluble polymer carboxylic acid, and the water-soluble polymer carboxylic acid. The purpose is to further promote the cross-linking reaction with water-soluble polymeric cross-linking agents that could not be completed due to steric hindrance depending on the acid, and to further improve the storage stability by reducing the reactive sites and to stabilize the chargeability Used in.

  As the acidic pH adjuster, a water-soluble compound having a carboxyl group in the molecule, and preferably a lower molecular weight compound than the water-soluble polymer carboxylic acid is used. Either a monocarboxylic acid having one carboxyl group in the molecule or a polycarboxylic acid having a plurality of carboxyl groups can be used, and the combination of these is also preferred.

  In order to satisfy the deactivation of the water-soluble polymer-based crosslinking agent at the same time, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid. Polyvalent carboxylic acids such as acid, maleic acid, oxaloacetic acid, mesaconic acid, itaconic acid, citraconic acid, citric acid, trimellitic acid, pyromellitic acid, and ethylenetetracarboxylic acid are preferably used. Not only the site where the three-dimensional structure is formed by crosslinking but also the terminal can be terminated with a carboxylic acid, which is advantageous for the charge stability of negatively charged toners when nitrogen containing a lone pair is included in the functional group of the water-soluble crosslinking agent. Because there is. There are metal salts of these polyvalent carboxylic acids, ammonium salts thereof, esterified products thereof, mixtures of polymers thereof, and the like. The molecule may contain elements such as halogen, nitrogen and sulfur, structures such as heterocycles and cycloalkanes.

  On the other hand, monocarboxylic acids such as formic acid, acetic acid and propionic acid are preferably used for the purpose of imparting hydrophobicity and simultaneously satisfying the deactivation of the water-soluble polymer crosslinking agent.

  By mixing the polyvalent carboxylic acid and the monocarboxylic acid in an arbitrary ratio, it is possible to simultaneously satisfy the purpose of crosslinking, hydrophobization, and deactivation of the water-soluble polymer crosslinking agent. When both are used in combination, it is preferable to add a monocarboxylic acid and a polyvalent carboxylic acid in this order when priority is given to the stability of negative charge. On the other hand, when priority is given to hydrophobicity, it is preferable to add polycarboxylic acid and monocarboxylic acid in this order.

The molecule of the polyvalent or monocarboxylic acid may contain a structure such as an element such as halogen, nitrogen or sulfur, a heterocyclic ring, or cycloalkane.
By mixing the polyvalent carboxylic acid and the monocarboxylic acid in an arbitrary ratio, it is possible to simultaneously satisfy the purpose of crosslinking, hydrophobization, and deactivation of the water-soluble polymer crosslinking agent.

  As long as the acidic pH adjusting effect is maintained, a part of the carboxy group in the polyvalent or monocarboxylic acid may be converted into a metal salt, ammonium salt, polymerization (for example, emulsion polymerization of acrylic acid in a slurry), etc. It can also be summed up.

When giving priority to hydrophobization, it is preferable to increase the ratio of monocarboxylic acid when using monocarboxylic acid or when using it together with polyvalent carboxylic acid.
When it is desired to stably obtain negative charge of the toner itself, such as when the functional group of the water-soluble crosslinking agent contains nitrogen having a lone electron pair and the functional group equivalent is high, the crosslink density is increased. Or when used in combination with a monocarboxylic acid, it is preferable to increase the ratio of the polyvalent carboxylic acid.

  The aqueous dispersion after the addition of the water-soluble polymer-based crosslinking agent and the water-soluble polymer-based carboxylic acid may be heated in order to promote the crosslinking reaction within a range that does not cause inconvenience (for example, colorant alteration). . This is because the necessary crosslinking reaction can be carried out in a short time with a small amount of the water-soluble crosslinking agent and a small amount of the water-soluble polymer carboxylic acid. The heating temperature is preferably 30 ° C to 95 ° C, particularly 35 ° C to 80 ° C. In order to produce a toner with improved low-temperature fixability by reacting in water, or when heating above the glass transition point of the binder resin, the pH should be adjusted so that the reaction system becomes alkaline. Thereby, coalescence of the core particles during heating can be suppressed. In this case, after heating the glass transition point or higher in an acidic system, the crosslinking reaction is allowed to proceed in a necessary and sufficient time, and the water-soluble polymer crosslinking agent is end-treated with carboxylic acid. It is preferable to make the system alkaline and to heat the glass transition point or higher of the binder resin. The addition amount of the water-soluble polymer-based crosslinking agent and the water-soluble polymer-based carboxylic acid is preferably 0.01% to 50%, particularly 0.01% to 20%, respectively, with respect to the core particles.

  Next, a supplementary description will be given of a preferable embodiment of producing core particles. The core particles (toner particles before encapsulation) used in the embodiment of the present invention contain a colorant in addition to at least the binder resin having a carboxyl group described above.

  Examples of the colorant include carbon black, organic or inorganic pigments and dyes. For example, carbon black includes acetylene black, furnace black, thermal black, channel black, ketjen black, and the like. Examples of yellow pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 74, 81, 83, 93, 95, 97, 98, 109, 117, 120, 137, 138, 139, 147, 151, 154, 167, 173, 180, 181, 183, 185, C.I. I. Bat yellow 1, 3, 20, etc. are mentioned. These may be used alone or in combination. Examples of magenta pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 150, 163, 184, 185, 202, 206, 207, 209, 238, C.I. I. Pigment violet 19, C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35, etc. are mentioned. These may be used alone or in combination. Examples of cyan pigments include C.I. I. Pigment blue 2, 3, 15, 16, 17, C.I. I. Bat Blue 6, C.I. I. Acid Blue 45 and the like. These may be used alone or in combination.

  The core particles including at least a binder resin having a carboxyl group and a colorant preferably include a release agent. Further, an erasable color material may be used as the colorant. Further, a charge control agent may be included.

  Examples of the release agent include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and fats such as acid value polyethylene wax. Oxides of aromatic hydrocarbon waxes, or block copolymers thereof, plant waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax, rice wax, animal waxes such as beeswax, lanolin, spermaceti Mineral waxes such as ozokerite, ceresin and petrolactam, waxes based on fatty acid esters such as montanic ester wax and castor wax, and fatty acid esters such as deoxidized carnauba wax. Or and the like that were de-oxidation all. Further, saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkyl carboxylic acids having a long-chain alkyl group, unsaturated fatty acids such as brassic acid, eleostearic acid, valinalic acid, stearyl alcohol , Saturated alcohols such as eicosyl alcohol, behenyl alcohol, carnauvir alcohol, seryl alcohol, melyl alcohol, or long chain alkyl alcohols having a long chain alkyl group, polyhydric alcohols such as sorbitol, linoleic acid amide, oleic acid Amide, fatty acid amide such as lauric acid amide, methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, saturated fatty acid bis amide such as hexamethylene bis stearic acid amide, Unsaturated fatty acid amides such as lenbis oleic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide, m-xylene bis stearic acid amide, Aromatic bisamides such as N, N'-distearylisophthalic amide, fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally referred to as metal soap), aliphatic Hydroxyl obtained by hydrogenating waxes grafted to hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid, partially esterified products of fatty acids and polyhydric alcohols such as behenic acid monoglycerides, and vegetable oils and fats. Methyl Este Having a Group Compounds.

  As the charge control agent, for example, a metal-containing azo compound is used, and the metal element is preferably a complex, complex salt of iron, cobalt, chromium, or a mixture thereof. In addition, a metal-containing salicylic acid derivative compound can be used, and the metal element is preferably a complex, complex salt of zirconium, zinc, chromium, boron, or a mixture thereof.

An erasable colorant can be used as the colorant. The erasable color material contains a color developing compound, a developer, and, if necessary, a color erasing agent.
The color developing compound is typically a leuco dye, and is an electron donating compound capable of developing color with a developer. Examples thereof include diphenylmethane phthalides, phenyl indolyl phthalides, indolyl phthalides, diphenyl methane azaphthalides, phenyl indolyl azaphthalides, fluorans, styrinoquinolines, diazarhodamine lactones, and the like.

  Specifically, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) Phthalide, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (2- Ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- [2-ethoxy-4- (N-ethylanilino) phenyl] -3- (1 -Ethyl-2-methylindol-3-yl) -4-azaphthalide, 3,6-diphenylaminofluorane, 3,6-dimethoxyfluorane, 3,6-di-n-butoxy Luolan, 2-methyl-6- (N-ethyl-Np-tolylamino) fluorane, 2-N, N-dibenzylamino-6-diethylaminofluorane, 3-chloro-6-cyclohexylaminofluorane, 2- Methyl-6-cyclohexylaminofluorane, 2- (2-chloroanilino) -6-di-n-butylaminofluorane, 2- (3-trifluoromethylanilino) -6-diethylaminofluorane, 2- (N -Methylanilino) -6- (N-ethyl-Np-tolylamino) fluorane, 1,3-dimethyl-6-diethylaminofluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-anilino-3 -Methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-di-n-butylaminofluorane, -Xylidino-3-methyl-6-diethylaminofluorane, 1,2-benz-6-diethylaminofluorane, 1,2-benz-6- (N-ethyl-N-isobutylamino) fluorane, 1,2-benz -6- (N-ethyl-N-isoamylamino) fluorane, 2- (3-methoxy-4-dodecoxystyryl) quinoline, spiro [5H- (1) benzopyrano (2,3-d) pyrimidine-5, 1 '(3'H) isobenzofuran] -3'-one, 2- (diethylamino) -8- (diethylamino) -4-methyl-, spiro [5H- (1) benzopyrano (2,3-d) pyrimidine- 5,1 ′ (3′H) isobenzofuran] -3′-one, 2- (di-n-butylamino) -8- (di-n-butylamino) -4-methyl-, spiro [5H- ( 1) Be Nzopyrano (2,3-d) pyrimidine-5,1 '(3'H) isobenzofuran] -3'-one, 2-di-n-butylamino) -8- (diethylamino) -4-methyl-, spiro [5H- (1) benzopyrano (2,3-d) pyrimidine-5,1 '(3'H) isobenzofuran] -3'-one, 2- (di-n-butylamino) -8- (N- Ethyl-Ni-amylamino) -4-methyl-, spiro [5H- (1) benzopyrano (2,3-d) pyrimidine-5,1 '(3'H) isobenzofuran] -3'-one, 2 -(Di-n-butylamino) -8- (di-n-butylamino) -4-phenyl, 3- (2-methoxy-4-dimethylaminophenyl) -3- (1-butyl-2-methylindole) -3-yl) -4,5,6,7-tetrachlorophthalide 3- (2-Ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4,5,6,7-tetrachlorophthalide, 3- (2-ethoxy- 4-diethylaminophenyl) -3- (1-pentyl-2-methylindol-3-yl) -4,5,6,7-tetrachlorophthalide. Furthermore, a pyridine type, a quinazoline type, a bisquinazoline type compound, etc. can be mentioned. You may use these in mixture of 2 or more types.

  The color developer for coloring the color former is an electron accepting compound that gives protons to the leuco dye. For example, phenols, phenol metal salts, carboxylic acid metal salts, aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms, sulfonic acids, sulfonates, phosphates, phosphate metal salts, acidic phosphate esters, There are acidic phosphoric acid ester metal salts, phosphorous acids, phosphite metal salts, monophenols, polyphenols, 1,2,3-triazole and derivatives thereof, and further substituents thereof are alkyl groups, aryl groups, acyls Groups, alkoxycarbonyl groups, carboxy groups and esters or amide groups thereof, halogen groups, and the like, bis-type, tris-type phenols, phenol-aldehyde condensation resins, and the like, and metal salts thereof. You may use these in mixture of 2 or more types.

  Specifically, phenol, o-cresol, tertiary butylcatechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, p-hydroxy N-butyl benzoate, n-octyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, dihydroxybenzoic acid or its esters such as 2,3-dihydroxybenzoic acid, methyl 3,5-dihydroxybenzoate, resorcin, gallic Acid, dodecyl gallate, ethyl gallate, butyl gallate, propyl gallate, 2,2-bis (4-hydroxyphenyl) propane, 4,4-dihydroxydiphenyl sulfone, 1,1-bis (4-hydroxyphenyl) Eta 2,2-bis (4-hydroxy-3-methylphenyl) propane, bis (4-hydroxyphenyl) sulfide, 1-phenyl-1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis ( 4-hydroxyphenyl) -3-methylbutane, 1,1-bis (4-hydroxyphenyl) -2-methylpropane, 1,1-bis (4-hydroxyphenyl) n-hexane, 1,1-bis (4- Hydroxyphenyl) n-heptane, 1,1-bis (4-hydroxyphenyl) n-octane, 1,1-bis (4-hydroxyphenyl) n-nonane, 1,1-bis (4-hydroxyphenyl) n- Decane, 1,1-bis (4-hydroxyphenyl) n-dodecane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy) Enyl) ethyl propionate, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2,2-bis (4-hydroxyphenyl) n-heptane, 2,2-bis (4-hydroxyphenyl) n-nonane, 2,4-dihydroxyacetophenone, 2,5-dihydroxyacetophenone, 2,6-dihydroxyacetophenone, 3,5-dihydroxyacetophenone, 2,3 , 4-trihydroxyacetophenone, 2,4-dihydroxybenzophenone, 4,4'-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2 ', 4 4'-tetrahydroxybenzophenone, 2,3,4,4 '-Tetrahydroxybenzophenone, 2,4'-biphenol, 4,4'-biphenol, 4-[(4-hydroxyphenyl) methyl] -1,2,3-benzenetriol, 4-[(3,5-dimethyl -4-hydroxyphenyl) methyl] -1,2,3-benzenetriol, 4,6-bis [(3,5-dimethyl-4-hydroxyphenyl) methyl] -1,2,3-benzenetriol, 4, 4 ′-[1,4-phenylenebis (1-methylethylidene) bis (benzene-1,2,3-triol)], 4,4 ′-[1,4-phenylenebis (1-methylethylidene) bis ( 1,2-benzenediol)], 4,4 ′, 4 ″ -ethylidenetrisphenol, 4,4 ′-(1-methylethylidene) bisphenol, methylenetris-p-cle There is Lumpur and the like.

  In a preferred embodiment, a color erasing agent is contained. The color erasing agent is known in the three-component system of a color developing compound, a color developing agent, and a color erasing agent, as long as it can inhibit the color development reaction caused by the leuco dye and the color developer by heat and can be made colorless. Can be used.

As the color erasing agent, in particular, it is known from JP-A-60-264285, JP-A-2005-1369, JP-A-2008-280523, etc. In the above, what provides a color erasing mechanism showing temperature hysteresis is excellent in instantaneous erasability. When this colored three-component mixture is heated to a specific decoloring temperature Th or higher, it can be decolored. Furthermore, even if the decolored mixture is cooled to a temperature equal to or lower than Th, the decolored state is maintained. When the temperature is further lowered, the color development reaction by the leuco dye and the developer is restored again at a specific recoloring temperature Tc or less, and a reversible color erasing reaction that returns to the color development state can be caused. In particular, the decolorizer used in the present invention preferably satisfies the relationship Th>Tr> Tc when the room temperature is Tr.
Examples of the color erasing agent capable of causing this temperature hysteresis include alcohols, esters, ketones, ethers, and acid amides.

  Particularly preferred are esters. Specifically, a carboxylic acid ester containing a substituted aromatic ring, an ester of a carboxylic acid and an aliphatic alcohol containing an unsubstituted aromatic ring, a carboxylic acid ester containing a cyclohexyl group in the molecule, a fatty acid and an unsubstituted aromatic alcohol or Ester of phenol, fatty acid and branched fatty alcohol, dicarboxylic acid and aromatic alcohol or branched fatty alcohol, dibenzyl cinnamate, heptyl stearate, didecyl adipate, dilauryl adipate, dimyristyl adipate, adipic acid Examples include dicetyl, distearyl adipate, trilaurin, trimyristin, tristearin, dimyristin, distearin and the like. You may use these in mixture of 2 or more types.

The erasable colorant is preferably encapsulated. Methods for forming the encapsulated colorant include interfacial polymerization, coacervation, in situ polymerization, submerged drying, submerged cured coating, and the like.
In particular, an in-situ method using melamine resin as a shell component, an interfacial polymerization method using urethane resin as a shell component, and the like are preferable.

  In the case of the In-Situ method, first, the above three components (color developing compound, color developer, and decoloring agent added as necessary) are dissolved and mixed, and emulsified in a water-soluble polymer or surfactant aqueous solution. Let Then, it can encapsulate by adding melamine formalin prepolymer aqueous solution, heating, and superposing | polymerizing.

  In the case of the interfacial polymerization method, the above three components and a polyvalent isocyanate prepolymer are dissolved and mixed and emulsified in a water-soluble polymer or a surfactant aqueous solution. Then, it can encapsulate by adding polyvalent bases, such as diamine or diol, and heat-polymerizing.

  The erasable colorant has a 50% volume average diameter Dv (laser diffraction type particle size distribution measuring device: particle size giving cumulative 50% by volume based on the particle size distribution measured with “SALD7000” manufactured by Shimadzu Corporation), 0.5 It is preferable that it is -3.5 micrometers. It has been experimentally confirmed that a colorant having a Dv outside the range of 0.5 to 3.5 μm deteriorates the incorporation into the toner particles. The mechanism by which the incorporation of small-diameter colorants deteriorates is not precisely known, but especially when encapsulated colorants are used, incorporation into the binder resin worsens when the particle diameter is less than a certain value. At the same time, it has been confirmed that the amount of fine powder generated increases.

  In addition, the encapsulated colorant depends on the specific color developing compound and the type of the color developer, but by placing the encapsulated colorant at a low temperature of −20 to −30 ° C., for example, A color is developed by combining with a developer.

  The agglomeration method, which is one of the methods for producing core particles containing at least the binder resin having a carboxyl group and the colorant of the present invention, will be described. According to the agglomeration method, after producing precursor fine particles containing at least a binder resin, an agglomerate is created by adding an aggregating agent to the fine particles, and the temperature is raised to a temperature higher than the glass transition temperature of the binder resin by heating. Core particles can be obtained by fusing the surfaces.

  A method for preparing a dispersion of precursor fine particles containing at least a binder resin can be prepared by a known method. For example, in the case of binder resin particle dispersion, a polymerization method obtained by polymerizing monomers or resin intermediates such as emulsion polymerization, seed polymerization, miniemulsion polymerization, suspension polymerization, interfacial polymerization, in-situ polymerization, and binder resin , Phase inversion emulsification method to obtain particles by using a solvent, alkali, surfactant, or softening by heating to form an oil phase, and adding an aqueous phase mainly containing water, solvent or heating a binder resin And a mechanical emulsification method in which the mixture is softened by using a high-pressure atomizer, a rotor stirrer type stirrer, or the like, and mechanically atomized into an aqueous medium. In the case of a release agent particle dispersion and a charge control agent particle dispersion, these materials are mechanically placed in an aqueous medium using a high-pressure atomizer, rotor stirrer stirrer, media atomizer, etc. It can be obtained by a mechanical atomization method for forming fine particles.

  On the other hand, in addition to these methods for preparing fine particles individually, the toner component materials are melt-kneaded or mixed and used in an aqueous medium using a high-pressure atomizer, rotor stirrer stirrer, media atomizer, etc. There is also a method of mechanically making fine particles. This method is a very excellent production method because the toner component fine particles can be prepared at one time, so that the process can be simplified, and further, the release agent, the charge control agent and the like can be uniformly dispersed in the binder resin.

Next, a specific example of a method for preparing a precursor fine particle dispersion containing at least a binder resin by emulsion polymerization, which is one of polymerization methods, will be described.
First, an oil phase component in which a vinyl polymerizable monomer and a chain transfer agent as necessary are mixed is prepared. Polymerization is carried out by emulsifying and dispersing them in an aqueous phase component which is an aqueous surfactant solution, adding a water-soluble polymerization initiator and heating. The oil phase component may be mixed with a toner component, such as a release agent or a charge control agent. In addition, a dispersion in which fine particles such as a release agent and a charge control agent are dispersed in an aqueous medium may be added during the polymerization process, and these components may be contained in the emulsion polymerization particles. By this emulsion polymerization, a fine particle dispersion of 0.01 to 1 μm of a toner component containing at least a binder resin can be prepared. As a method for this emulsion polymerization, polymerization may be performed while dropping an oil phase component in an aqueous phase component, or a polymerization initiator may be added again during the polymerization in order to adjust the molecular weight.
Next, a specific example of a method for preparing a dispersion of first fine particles containing at least a binder resin by a phase inversion emulsification method will be described.

  First, an oil phase component including a toner component containing at least a binder resin is heated and melted. An aqueous solution containing a surfactant and a pH adjuster is gradually added thereto. As the aqueous solution is added, the phase is changed from W / O to O / W. After completion of the phase inversion, a fine particle dispersion of a toner component of 0.01 to 5 μm containing at least a binder resin can be prepared by cooling. Here, a surfactant, a pH adjuster, a solvent, ion-exchanged water, or the like may be added in advance to the oil phase component. In particular, when a solvent is added, the viscosity of the oil phase component decreases. In some cases, there is no need for heating. However, when a solvent is used, it is necessary to remove the solvent after phase inversion emulsification.

Next, a method for aggregating the precursor fine particles will be described.
First, a flocculant is added to the fine particle dispersion. The addition amount of the flocculant varies depending on the dispersion stability of the fine particles, and is large when the dispersion stability is high and decreases when the dispersion stability is low. It also varies depending on the type of flocculant. When aluminum sulfate is used as the flocculant, 0.1 to 50 wt%, preferably 0.5 to 10 wt% is added to the fine particles. After adding the flocculant, for example, in the case of a strong flocculant flocculant such as aluminum sulfate, an agglomerated particle size of 0.1 to 10 μm is obtained. On the other hand, in the case of a weak coagulant such as sodium chloride, aggregation may not occur when the coagulant is added. In this addition, a rotor-stator type disperser is preferably used in order to prevent rapid aggregation of fine particles. Similarly, in order to prevent rapid agglomeration, the pH of the fine particle dispersion may be adjusted and a surfactant may be added before the aggregating agent is added. By these operations, it is possible to make the particle diameter of the finally obtained toner uniform.

Next, aggregation by heating is performed. Aggregated particles having a particle size from 2 μm to the target particle size are produced by heating.
Next, fusion by heating is performed. If necessary, a stabilizer such as a pH adjuster or a surfactant is added to the aggregated particles to stabilize the aggregated particles, and then heated to at least the Tg of the binder resin. Fusing the surface. By this fusion, the final target particle diameter of the toner particles is obtained.
Depending on the type of fine particles, the solid content concentration, and the type of aggregating agent, agglomeration and fusion may be performed simultaneously.

  In addition, the stirring conditions in the aggregation and fusion greatly affect the particle size and particle size distribution. The stirring speed is good under conditions that give moderate shearing. If the shearing is too weak, the particle size becomes large and coarse particles are easily formed. On the other hand, if it is too strong, the particle size becomes small and it becomes easy to make fine powder. A baffle may be installed in the reaction tank. The baffle has the effect of suppressing bubble smearing, the effect of making the stirring state in the tank uniform, and the effect of increasing shear. In addition to the stirring conditions, the rate of temperature rise, the rate of addition of additives, and the like have a great influence on the particle size and particle size distribution.

  If necessary, the surface of the aggregated particles can be coated with a resin. For this purpose, for example, resin particles are added to the aggregated particle dispersion, and the resin particles are adhered to the surface of the aggregated particles by adding a coagulant and adjusting the pH, and then the resin particles are fused to the surface of the aggregated particles. The method of wearing is taken.

    This coating makes it possible to enclose the color material and the release agent on the toner surface, and the stability of the image during continuous paper feeding is improved. However, in the present invention, the resin to be coated preferably has the same resin composition as the aggregated particles so as not to impair the fixing property.

Mainly, the production apparatus exemplified below can be used in the production process of the core particles described above.
The kneader is not particularly limited as long as melt kneading is possible, and examples thereof include a single screw extruder, a twin screw extruder, a pressure kneader, a Banbury mixer, and a Brabender mixer. Specifically, FCM (made by Kobe Steel), NCM (made by Kobe Steel), LCM (made by Kobe Steel), ACM (made by Kobe Steel), KTX (made by Kobe Steel), GT (manufactured by Ikegai Co., Ltd.), PCM (manufactured by Ikegai Co., Ltd.), TEX (manufactured by Nippon Steel Works Co., Ltd.), TEM (manufactured by Toshiba Machine Co., Ltd.), ZSK (manufactured by Warner Company), and Nidex (manufactured by Mitsui Mining Co., Ltd.) It is done.

  The pulverizer is not particularly limited as long as it can be pulverized in a dry manner, and examples thereof include a ball mill, an atomizer, a bantam mill, a pulverizer, a hammer mill, a roll crusher, a cutter mill, and a jet mill.

  The atomizer is not particularly limited as long as it can be atomized by a wet method. For example, Nanomizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.), Optimizer (manufactured by Sugino Machine Co., Ltd.), NANO3000 (manufactured by Miki Co., Ltd.), Microfluidizer, etc. High-pressure atomizers such as Dizer (manufactured by Mizuho Kogyo Co., Ltd.), homogenizer (manufactured by Izumi Food Machinery), Ultra Turrax (manufactured by IKA Japan), TK auto homomixer (manufactured by Primix), TK pipeline homomixer (Manufactured by Primix), TK Philmix (manufactured by Primix), Claremix (manufactured by M Technique), Claire SS5 (manufactured by M Technique), Cavitron (manufactured by Eurotech), Fine Flow Mill (Pacific) Rotor Stator Stirrer like Viscomil (Imek) Manufactured), Apex mill (manufactured by Kotobuki Kogyo Co., Ltd.), Star mill (manufactured by Ashizawa, Finetech), DCP Super Flow (manufactured by Eirich Japan), MPP mill (manufactured by Inoue Seisakusho), spike mill (manufactured by Inoue Seisakusho), Mighty Examples thereof include a media stirrer such as a mill (manufactured by Inoue Seisakusho) and an SC mill (manufactured by Mitsui Mining). These atomizers can also be used when mixing toner component particles and an aggregating agent.

As the cleaning device, for example, a centrifugal separator or a filter press is preferably used. As the cleaning liquid, for example, water, ion exchange water, purified water, water adjusted to acidity, water adjusted to basicity, or the like is used.
As the drying device, for example, a vacuum dryer, an airflow dryer, a fluid dryer, or the like is preferably used.

  Examples of dry mixers include Henschel mixer (Mitsui Mining Co., Ltd.), super mixer (Kawata Co., Ltd.), ribocorn (Okawara Seisakusho Co., Ltd.), Nauter mixer (Hosokawa Micron Co., Ltd.), and turbulizer (Hosokawa Micron Co., Ltd.). , Cyclomix (manufactured by Hosokawa Micron Co., Ltd.), spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.), and Laedige mixer (manufactured by Matsubo Co., Ltd.).

(Manufacture of toner)
As described above, a water-soluble crosslinking agent, a water-soluble polymer carboxylic acid, and an acidic pH adjuster are sequentially added to the aqueous dispersion of core particles as described above to cause a crosslinking reaction, thereby encapsulating toner particles. After obtaining the dispersion liquid, encapsulated toner particles are obtained by washing, solid-liquid separation, and drying. A toner can be obtained by adding an external additive to the toner particles.

  As the external additive, 0.01 to 20% by weight of inorganic fine particles with respect to the toner particles are added and mixed to adhere to the surface of the toner particles, whereby the fluidity and chargeability of the toner can be adjusted. . As such inorganic fine particles, fine particles having an average particle diameter of about 1 to 500 nm, such as silica, titania, alumina, strontium titanate, and tin oxide, can be used alone or in admixture of two or more. The inorganic fine particles are preferably surface-treated with a hydrophobizing agent from the viewpoint of improving environmental stability. In addition to such inorganic oxides, resin fine particles having a size of 1 μm or less may be externally added to improve cleaning properties.

Such a toner is used in an image forming apparatus such as a single tandem or quadruple tandem type copying machine MFP (Multi-Function Peripheral).

FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus to which toner according to the present embodiment is applicable.
As shown in FIG. 1, a four-tandem color copier MFP (Multi-Function Peripheral) MFP (e-studio 4520c) 1 includes a scanner unit 2 and a paper discharge unit 3 on the upper side.

  The color copying machine MFP1 includes four sets of images of yellow (Y), magenta (M), cyan (C), and black (K) arranged in parallel along the lower side of the intermediate transfer belt (intermediate transfer medium) 10. It has forming stations 11Y, 11M, 11C and 11K.

  Each of the image forming stations 11Y, 11M, 11C, and 11K includes a photosensitive drum (image carrier) 12Y, 12M, 12C, and 12K. Around the photosensitive drums 12Y, 12M, 12C, and 12K, charging chargers 13Y, 13M, 13C, and 13K, developing devices 14Y, 14M, 14C, and 14K, and a photosensitive member cleaning device are arranged along the rotation direction of the arrow m. 15Y, 15M, 15C and 15K are arranged.

  Exposure by a laser exposure device (latent image forming device) 16 between the charging chargers 13Y, 13M, 13C and 13K around the photosensitive drums 12Y, 12M, 12C and 12K and the developing devices 14Y, 14M, 14C and 14K. Are irradiated to form electrostatic latent images on the photosensitive drums 12Y, 12M, 12C, and 12K.

  The developing devices 14Y, 14M, 14C, and 14K have two-component developers including yellow (Y), magenta (M), cyan (C), and black (K) toners and carriers, respectively. Toner is supplied to the electrostatic latent images on 12M, 12C and 12K.

  The intermediate transfer belt 10 is stretched by a backup roller 21, a driven roller 20, and first to third tension rollers 22-24. The intermediate transfer belt 10 faces and contacts the photosensitive drums 12Y, 12M, 12C, and 12K. The primary transfer for primary transfer of the toner images on the photosensitive drums 12Y, 12M, 12C and 12K to the intermediate transfer belt 10 is provided at a position of the intermediate transfer belt 10 facing the photosensitive drums 12Y, 12M, 12C and 12K. Transfer rollers 17Y, 17M, 17C and 17K are provided. The primary transfer rollers 17Y, 17M, 17C and 17K are conductive rollers, respectively, and apply a primary transfer bias voltage to each of these primary transfer portions.

  A secondary transfer roller 27 is disposed at a secondary transfer portion that is a transfer position supported by the backup roller 21 of the intermediate transfer belt 10. In the secondary transfer portion, the backup roller 21 is a conductive roller, and a predetermined secondary transfer bias is applied. When the sheet paper (final transfer medium) to be printed passes between the intermediate transfer belt 10 and the secondary transfer roller 27, the toner image on the intermediate transfer belt 10 is secondarily transferred onto the sheet paper. After the completion of the secondary transfer, the intermediate transfer belt 10 is cleaned by the belt cleaner 10a.

  Below the laser exposure device 16, there is provided a paper feed cassette 4 that supplies the sheet paper P <b> 1 in the direction of the secondary transfer roller 27. The right side of the color copying machine 1 is provided with a manual feed mechanism 31 that feeds the sheet paper P2 manually. A pickup roller 4a, a separation roller 28a, a transport roller 28b, and a registration roller pair 36 are provided between the paper feed cassette 4 and the secondary transfer roller 27, and these constitute a paper feed mechanism.

  Between the manual feed tray 31a of the manual feed mechanism 31 and the registration roller pair 36, a manual pickup roller 31b and a manual feed separation roller 31c are provided. Further, a media sensor 39 that detects the type of the sheet paper is disposed on the vertical conveyance path 34 that conveys the sheet paper from the paper feed cassette 4 or the manual feed tray 31 a toward the secondary transfer roller 27. The color copying machine 1 can control the sheet paper conveyance speed, transfer conditions, fixing conditions, and the like based on the detection result of the media sensor 39. A fixing device 30 is provided downstream of the secondary transfer unit along the direction of the vertical conveyance path 34. The sheet paper taken out from the paper feed cassette 4 or fed from the manual feeding mechanism 31 is conveyed along the vertical conveyance path 34 to the fixing device 30 through the registration roller pair 36 and the secondary transfer roller 27.

  The fixing device 30 includes a fixing belt 53 wound around a pair of heating rollers 51 and a driving roller 52, and an opposing roller 54 disposed to face the heating roller 51 with the fixing belt 53 interposed therebetween. A sheet paper having a toner image transferred by the secondary transfer unit is introduced between the fixing belt 53 and the opposing roller 54, and the toner image transferred to the sheet paper is heat-treated by heating with the heating roller 51. And fix. A gate 33 is provided downstream of the fixing device 30 and distributes in the direction of the paper discharge roller 41 or the direction of the re-transport unit 32. The sheet paper guided to the paper discharge roller 41 is discharged to the paper discharge unit 3. The sheet paper guided to the re-transport unit 32 is guided again toward the secondary transfer roller 27.

  The image forming station 11Y integrally includes a photosensitive drum 12Y and process means, and is detachably provided on the image forming apparatus main body. The process means refers to at least one of the charging charger 13Y, the developing device 14Y, and the photoreceptor cleaning device 15Y. The image forming stations 11M, 11C, and 11K have the same configuration as the image forming station 11Y. Each of the image forming stations 11Y, 11M, 11C, and 11K may be detachable from the image forming apparatus, or may be detachable from the image forming apparatus as an integrated image forming unit 11.

  Hereinafter, embodiments of the present invention will be described more specifically with reference to examples and comparative examples. Including the following description, the measurement of the physical property values described in this specification and the evaluation of the obtained toner were performed by the following methods.

(Acid value of binder resin having carboxyl group)
It measured according to JIS K0070. However, the measurement solvent was a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

(Molecular weight of water-soluble polymer carboxylic acid)
It is a weight average molecular weight in terms of polyethylene glycol by gel permeation chromatography (hereinafter referred to as “GPC”), and was measured under the following GPC measurement conditions.
<GPC molecular weight measurement conditions>
Column used: TSK guard Column SWXL + TSKge1 G4000SWXL + G3000SWXL + G2000SWXL manufactured by Tosoh Corporation
Eluent: 115.6 g of sodium acetate trihydrate is dissolved in a mixed solvent of 10999 g of water and 6001 g of acetonitrile, and an eluent solution adjusted to pH 6.0 with acetic acid is used.
Injection volume: 100 μL of 0.5% eluent solution
Eluent flow rate: 0.8 mL / min
Column temperature: 40 ° C
Standard substance: polyethylene glycol, peak top molecular weight (Mp) 272500, 219300, 85000, 46000, 24000, 12600, 4250, 7100, 1470
Detector: Japan Waters 410 Differential refraction detector Analysis software: Japan Waters MILLENNIUM Ver. 3.21

(Fixability)
The obtained toner is put into an electrophotographic composite machine modified for evaluation (“e-STUDIO 3520c” manufactured by TOSHIBA TEC), an unfixed image is created, and a fixing machine modified for evaluation (30 mm / s) Then, the temperature was changed in increments of 2.5 ° C., and the minimum and maximum fixing temperatures at which no offset occurred were obtained to evaluate the fixability.

(Storability)
The storability is a toner performance that does not aggregate or solidify at a high temperature as a performance that can withstand the temperature in the main body of the electrophotographic composite machine and the temperature during transportation. In the storage stability evaluation method, 20 g of toner is put into a 100 cc polyethylene bottle and left in a thermostatic oven set at a predetermined temperature for 8 hours. Then, with a powder tester PT-E (manufactured by Hosokawa Micron Corporation) with a 42 mesh (mesh opening: 0.351 mm) sieve, sieve for 10 seconds with a 0.6 mm memory of the vibrometer (THERMO VIBRO VM4515S1) Judged by the remaining weight. A toner having a large amount of toner remaining on the sieve is determined as a toner having poor storage stability. The weight on the sieve is desirably as small as possible, and evaluation in the following Examples and Comparative Examples was performed according to the following criteria. A: 0.01 g or less, B: more than 0.01 g, 0.1 g or less, C: more than 0.1 g.

(Chargeability: q / m)
<Creation of frictionally charged particles>
Polyester resin toner (volume average particle diameter 5.8μ) 8 parts by weight Magnetic carrier (volume average particle diameter 50μ) (manufactured by Powdertech) 92 parts by weight After mixing the above, stir in a turbula mixer for 1 hour and friction A charged developer was obtained.

  The charge amount of the obtained developer was measured by a charge amount measuring device (TYPE TB-203 manufactured by Kyocera Chemical). Generally, if the charge amount is 20 (-μC / g) or more, toner scattering and fogging are difficult to occur. On the other hand, if the charge amount is less than 20 (-μC / g), defects such as toner scattering and fogging are caused. Is determined to occur easily. Under high temperature-high humidity conditions, the charge amount tends to decrease.

Prior to toner production in Examples and Comparative Examples, core particles (dispersions) were produced as follows.
<Creation of core particles>
Polyester resin (Mw: 10000, Tg: 50 ° C., Tm: 90 ° C., acid value (AV): 25) 90 parts by weight Pigment Blue 15: 3 (manufactured by Clariant) 5 parts by weight Rice wax 5 parts by weight.
After mixing the above components, the mixture was melt-kneaded in a biaxial kneader set at 120 ° C. to obtain a kneaded product.
The obtained kneaded product was coarsely pulverized to a volume average particle size of 0.1 mm or less with a coarse pulverizer (“Bantham Mill” manufactured by Hosokawa Micron Corporation) to obtain coarse particles.
A dispersion was prepared by mixing 30 parts by weight of the coarse particles, 3 parts by weight of sodium dodecylbenzenesulfonate as a surfactant, 2 parts by weight of dimethylaminoethanol and 65 parts by weight of ion-exchanged water as an alkaline pH adjuster.

  Next, a 12-m high-pressure pipe for heat exchange immersed in an oil bath as a heating part, a high-pressure pipe including a nozzle connected with 0.13 μm and 0.28 μm as a pressurizing part, 0.4, 1. High-pressure atomizer (Beauty) equipped with medium-pressure pipes connected with cells having pore diameters of 0, 0.75, 1.5, and 1.0 μm, and a 12-m heat exchange pipe that can be cooled with tap water as a cooling unit The dispersion of the coarse particles is subjected to atomization at 180 ° C. and 150 MPa, and the pressure is reduced while maintaining 180 ° C., and then cooled to 30 ° C. to obtain the atomized dispersion. Got. The obtained particles were measured with a laser diffraction particle size distribution analyzer (“SALD7000” manufactured by Shimadzu Corporation), and the 50% volume average particle diameter Dv was 0.52 μm.

  35 parts by weight of the obtained finely divided dispersion and 65 parts by weight of ion-exchanged water were mixed, and 10 parts by weight of a 5% aqueous solution of sodium hydrogen sulfate as a flocculant was added while stirring at 6500 rpm with a homogenizer (“T25” manufactured by IKA). The obtained dispersion was accommodated in an agglomeration reactor. Thereafter, the mixture was heated to 75 ° C. to obtain a core particle dispersion containing aggregated fused particles.

  When the particle diameter of the aggregated fused particles was measured with a Coulter counter (“Multisizer 3” manufactured by Coulter, Inc .; aperture diameter: 100 μm), the 50% volume average diameter Dv was 5.8 μm, and the 50% number average diameter Dp was 4. It was a sharp particle size distribution of .9 μm.

  The solid content of the obtained core particle dispersion is repeatedly filtered and washed with ion-exchanged water until the filtrate has a conductivity of 50 μS / cm, and further has a water content of 1.0 in a vacuum dryer. The core particles were obtained by drying until not more than% by weight.

Example 1
Dry core particles obtained above: 10 parts by weight Crosslinker: Water-soluble acrylic polymer aqueous solution having oxazoline group (“Epocross WS700” manufactured by Nippon Shokubai Co., Ltd., mass per mole of oxazoline group: 220) (solid content 25% ) 1.5 parts by weight Ion exchange water: 88.5 parts by weight were mixed and dispersed, adjusted to pH 8 with a 10% aqueous sodium hydroxide solution, and then heated to 50 ° C. while stirring with a paddle blade. After reaching 50 ° C,
0.1 part by weight of an aqueous solution obtained by diluting polyacrylic acid (“AQUALIC HL415” manufactured by Nippon Shokubai Co., Ltd., molecular weight 10,000, solid content 45%) to a solid content of 10% is added as a water-soluble polymer carboxylic acid, and 50 The solution was allowed to stand at 8 ° C. for 8 hours (the pH at this time was about 7), and then 20 parts by weight of a 1% aqueous solution of succinic acid was further added to lower the pH from 7 to 6, followed by 8 hours at 50 ° C. The crosslinking reaction was completed by allowing it to stand.

  Thereafter, the solid content of the obtained dispersion was repeatedly filtered and washed with ion-exchanged water, and washed until the filtrate had a conductivity of 50 μS / cm. Then, it dried with the vacuum dryer until the moisture content became 1.0 weight% or less, and obtained the dry particle | grains.

  After drying, 2 parts by weight of hydrophobic silica having a volume average particle diameter of 30 nm and 0.5 parts by weight of titanium oxide having a volume average particle diameter of 20 nm are attached to the toner particle surface as additives with respect to 100 parts by weight of toner particles. The desired toner for electrophotography was obtained.

(Example 2)
Core particles: 10 parts by weight Crosslinking agent: Epocross WS700 (manufactured by Nippon Shokubai Co., Ltd.) (solid content 25%) 1.5 parts by weight Ion-exchanged water: 88.5 parts by weight are mixed and dispersed, and stirred with a paddle blade. Heated to ° C. After reaching 50 ° C,
0.1 part by weight of an aqueous solution of 10% solid content of polyacrylic acid (“AQUALIC HL415” manufactured by Nippon Shokubai Co., Ltd., molecular weight 10,000) was added and allowed to stand at 50 ° C. for 8 hours (the pH at this point was 8) Then, 20 parts by weight of a 1% fumaric acid aqueous solution was further added to lower the pH from 8 to 7. Further, the pH was adjusted to 6 with a 3% aqueous acetic acid solution, and then allowed to stand at 50 ° C. for 8 hours. Thus, the crosslinking reaction was completed.

  Thereafter, the solid content (toner particles) of the obtained dispersion was subjected to filtration, washing, drying and external addition of hydrophobic silica and titanium oxide in the same manner as in Example 1 to obtain an electrophotographic toner.

<Comparative Example 1>
An electrophotographic toner is obtained in the same manner as in Example 1 except that a 1% aqueous solution of sodium benzoate is added to the reaction system after the crosslinking reaction by addition of an aqueous polyacrylic acid solution instead of a 1% aqueous solution of succinic acid. It was.

<Comparative example 2>
An electrophotographic toner was obtained in the same manner as in Example 1 except that sodium abietic acid was added to the reaction system after the crosslinking reaction by the addition of the polyacrylic acid aqueous solution instead of the 1% aqueous succinic acid solution.

<Comparative Example 3>
Core particles used in Example 1: 10 parts by weight Crosslinking agent: Water-soluble acrylic polymer aqueous solution having oxazoline group (“Epocross WS700” manufactured by Nippon Shokubai Co., Ltd., mass per mole of oxazoline group: 220) (solid content 25%) 1.5 parts by weight Acetic acid 3% aqueous solution: 0.9 parts by weight Ion exchange water: 87.6 parts by weight were mixed and dispersed to terminate the amide esterification reaction. (The ultimate pH was about 7), and then heated to 50 ° C. while stirring with a paddle blade. After reaching 50 ° C., an aqueous solution obtained by diluting polyacrylic acid (“AQUALIC HL415” manufactured by Nippon Shokubai Co., Ltd., molecular weight 10,000, solid content 45%) as a water-soluble polymer carboxylic acid to a solid content of 0.1% A part by weight was added and the mixture was allowed to stand at 50 ° C. for 8 hours. Thereafter, an electrophotographic toner was obtained in the same manner as in Example 1 except that 1% aqueous succinic acid solution was not added.

The toners obtained in the above Examples and Comparative Examples were evaluated for fixability, storage stability and chargeability by the methods described above.
The summary of the above examples and comparative examples and the evaluation results of the obtained toner are summarized in Table 1 below.

  If the result of the said Table 1 is seen, according to embodiment of this invention, the water-soluble polymer bridge | crosslinking which crosslinks with the core particle | grains which first contain the binder resin which has a carboxyl group, and a coloring agent first in an aqueous dispersion medium, and a carboxyl group. The toner of the example obtained by mixing with the water-soluble agent and cross-linking with the water-soluble polymer carboxylic acid and then adjusting the acidic pH by addition of a low molecular weight carboxylic acid is the fixing temperature obtained by increasing the maximum fixing temperature. It can be seen that an improvement in performance represented by an increase in area, an improvement in storage stability up to a relatively high temperature, and an improvement in chargeability under high temperature-high humidity conditions are realized. On the other hand, the performance improvement effect is not obtained in Comparative Examples 1 and 2 in which an alkali salt having no acidic pH adjusting effect is added instead of the low molecular weight carboxylic acid. In Comparative Example 3 in which 3% acetic acid was added at the same time as the water-soluble crosslinking agent and was allowed to exist until the temperature was raised to 50 ° C., the oxazoline group of the water-soluble crosslinking agent was consumed by acetic acid. Performance degradation is considered to have occurred because the crosslinking reaction between the added polyacrylic acid and the water-soluble crosslinking agent is insufficient.

Claims (2)

Obtained by sequentially treating the core particles containing at least a carboxyl group-containing binder resin and a colorant with a water-soluble polymer-based crosslinking agent that cross-links with a carboxyl group, a water-soluble polymer-based carboxylic acid, and an acidic pH adjuster. It has a resulting crosslinked coating layer, and a combination of the acidic pH adjuster is a water-soluble compound having a plurality of water-soluble compounds and carboxyl group having one less carboxyl groups molecular weight than the water-soluble polymeric carboxylic acids Toner characterized by the above. In an aqueous dispersion medium, first, a core resin containing at least a binder resin having a carboxyl group and a colorant is mixed with a water-soluble polymer-based crosslinking agent that undergoes a crosslinking reaction with the carboxyl group, and then a water-soluble polymer-based carboxylic acid. and mixed by adding an acidic pH adjusting agent is a water-soluble compound having a low carboxyl group molecular weight than the water-soluble polymeric carboxylic acids sequentially, producing how the toner, characterized in that to cause a crosslinking reaction .

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