JP2005077603A - Electrophotographic toner and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic toner giving good image quality and excellent in durability and a method for manufacturing the same. <P>SOLUTION: The electrophotographic toner comprises core parts consisting of fine resin particles of a polyester resin (A) obtained using a compound (a) having a structure obtained by hydrogenation of part or all of an aromatic ring and shell layers comprising an acrylic resin. In the method for manufacturing the electrophotographic toner, an aqueous dispersion (I) of fine particles of the polyester resin (A) obtained using the compound (a) having the structure obtained by hydrogenation of part or all of the aromatic ring is mixed with an aqueous dispersion (II) of fine particles of the acrylic resin, the fine resin particles (P1) and the fine resin particles (P2) are associated, and shell layers obtained by association of the fine resin particles (P2) are formed on the surfaces of the fine resin particles (P1) as core particles. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic toner having good image quality and excellent durability and a method for producing the same.

  In recent years, there has been an increasing demand for improvement in the quality of images obtained in electrophotographic toners. In response to such market demand, for example, aggregated particles are formed in a dispersion obtained by dispersing resin particles. There is a toner manufacturing method in which a separately prepared fine particle dispersion is added to and mixed with the aggregated particle dispersion to adhere the fine particles to the surface of the aggregated particles (see, for example, Patent Document 1). The toner obtained by the production method of Patent Document 1 is a toner having a core-shell structure in which the agglomerated particles are used as core particles and finely produced particles are attached to the surface of the core particles to form a shell layer. In Example 3, resin particles containing acrylic resin are used as core particles, and a toner having a core-shell structure is produced by associating resin particles of polyester resin with the surface of the core particles. However, although the image quality of the electrophotographic toner obtained in Patent Document 1 has improved to some extent, it has not yet achieved a level that meets market demands. Further, since the electrophotographic toner uses a polyester resin that easily absorbs moisture in the shell layer, the charge amount tends to decrease with time due to moisture absorption, and the durability is not sufficient.

JP-A-10-26842 (page 2, pages 10-11)

  An object of the present invention is to provide an electrophotographic toner having good image quality and excellent durability and a method for producing the same.

As a result of intensive studies to solve the above problems, the present inventors have found the following findings (1) to (3), and have completed the present invention.
(1) A core part comprising resin fine particles containing a polyester resin (A) obtained by using as a raw material a compound (a) having a structure obtained by hydrogenating a part or all of an aromatic ring as a raw material; An electrophotographic toner having a shell layer containing an acrylic resin (B) on the surface of the core portion has good compatibility between the acrylic resin and the polyester resin (A), no bleeding, and good image quality. Be.
(2) Since the electrophotographic toner has the core-shell structure, the polyester resin contained in the core particles is prevented from absorbing moisture, so that the amount of charge is not decreased with time and is excellent in durability.
(3) The electrophotographic toner comprises an aqueous dispersion (I) obtained by dispersing resin fine particles (P1) containing the polyester resin (A) in an aqueous dispersion, and an acrylic resin (B). The resin fine particles (P1) and the resin are mixed with an aqueous dispersion (II) obtained by dispersing resin fine particles (P2) having an average particle size smaller than the average particle size of the resin fine particles (P1) in an aqueous medium. It can be easily manufactured by associating the fine particles (P2) with the resin fine particles (P1) as core particles and forming a shell layer in which the resin fine particles (P2) are associated on the surface of the core particles.

  That is, the present invention provides a core portion comprising resin fine particles containing a polyester resin (A) obtained by using a compound (a) having a structure obtained by hydrogenating a part or all of an aromatic ring as a raw material. And providing a shell layer containing an acrylic resin (B) on the surface of the core part.

  The present invention also provides resin fine particles (P1) containing a polyester resin (A) obtained using a compound (a) having a structure obtained by hydrogenating a part or all of an aromatic ring as a raw material. An aqueous dispersion (I) dispersed in a dispersion and resin fine particles (P2) containing an acrylic resin (B) and having an average particle size smaller than the average particle size of the resin fine particles (P1) in an aqueous medium The aqueous dispersion (II) dispersed in the mixture is mixed, and the resin fine particles (P1) and the resin fine particles (P2) are associated to form the resin fine particles (P1) as core particles. The present invention provides a method for producing an electrophotographic toner, characterized in that a shell layer formed by associating fine particles (P2) is formed.

  Since the electrophotographic toner of the present invention uses the polyester resin (A) as the resulting polyester resin, it has good compatibility with the acrylic resin (B) contained in the shell layer and good image quality. Further, by disposing an acrylic meter resin as a core layer on the surface of the polyester resin fine particles that are likely to absorb moisture, the amount of charge due to moisture absorption is less likely to decrease with time, and the durability is also excellent.

The present invention is described in detail below.
The polyester resin (A) used in the present invention has a good compatibility with the acrylic resin (B), and a part or all of the aromatic ring is hydrogenated as a raw material in order to obtain an electrophotographic toner with good image quality. It is necessary to be a polyester resin obtained by using the compound (a) having a structure obtained in this manner.

  Examples of the polyester-based resin (A) include non-self-water-dispersible polyester-based resins that can be dispersed in fine particles in an aqueous medium by using an emulsifier, a suspension stabilizer, and the like; an emulsifier, a suspension stabilizer, and the like. Self-water such as a polyester resin that can be dispersed in fine particles in an aqueous medium, a polyester resin that contains acid groups or basic groups and can be dispersed in fine particles in an aqueous medium by neutralization thereof Examples thereof include dispersible polyester resins, among which self-water dispersible polyester resins are preferable. The polyester resin (A) is prepared by dissolving the polyester resin in one or more organic solvents that can dissolve the polyester resin at room temperature, such as tetrahydrofuran and methyl ethyl ketone, and then stirring the obtained resin solution. An aqueous medium (in the case of a non-self-water dispersible polyester resin, an aqueous medium containing an emulsifier, etc. Among the self-water dispersibility, a neutralizer in the case of a polyester resin that can be dispersed in an aqueous medium by neutralization) A polyester resin that can be dispersed and dispersed in the form of particles having an average particle size of 10 μm or less by phase inversion emulsification by adding dropwise an aqueous medium containing 1), and dispersed in a particle form of 0.1 μm or less. Possible polyester resins are particularly preferred.

  Examples of the self-water dispersible polyester resin include neutralized acid group-containing polyester resins such as sulfonic acid metal salts and carboxylic acid metal salts; neutralized basic group-containing polyester resins; hydroxypolyoxy Hydrophilic segment-containing polyester resin such as a polyester resin in which a so-called nonionic structure such as ethylene is introduced; an acid base such as a carboxyl group, an organic base such as alkanolamine, an inorganic base such as ammonia or sodium hydroxide Polyester resin that can be anionized in an aqueous phase by adding a neutralizing agent such as an amino acid, a basic group such as a pyridine ring, and a neutralizing agent such as an organic acid or an inorganic acid And polyester resins that can be cationized in the aqueous phase by adding Preferably containing polyester resin and acid group-containing polyester is particularly preferred acid group-containing polyester resin from it easily save a low hygroscopic property.

  Examples of the neutralized acid group-containing polyester resin include, for example, a polyester resin obtained using a compound having a neutralized acid group as an essential component, an acid group such as a carboxyl group, and neutralization. Examples include polyester resins obtained by neutralizing acid groups after preparing a polyester resin to be a self-water-dispersible polyester resin. Specific examples thereof include neutralized carboxyl group-containing polyester resins, neutralized sulfone group-containing polyester resins, and neutralized phosphoric acid group-containing polyester resins. When a polyester resin obtained by using a neutralized acid group-containing compound as an essential component is used as the self-water dispersible polyester resin, a neutralized sulfone group-containing polyester resin is preferable. When a polyester resin obtained by neutralizing an acid group after preparing a polyester resin to be a water-dispersible polyester resin, a neutralized carboxyl group-containing polyester resin is preferable. In addition, as an acid value at the time of removing neutralization of the neutralized acid group containing polyester-type resin, 1-100 are preferable and 5-40 are more preferable.

  The neutralized acid group-containing polyester resin is, for example, the carboxyl group-containing polyester resin, for example, an acid compound (a) having a structure obtained by hydrogenating part or all of the aromatic ring. Used as a part or all of the component and / or alcohol component, and if necessary, an acid component other than the compound (a), for example, a dibasic acid or an anhydride thereof, a tribasic or higher polybasic acid, a single base An acid component such as an acid or an alcohol component other than the compound (a), for example, a dihydric alcohol, a tri- or higher functional alcohol, a monohydric alcohol or the like is mixed and heated in a nitrogen atmosphere under heating. Can be prepared by a method such as dehydration condensation at a reaction temperature of 180 to 260 ° C. while measuring.

  Examples of the acid group-containing polyester resin include carboxyl group-containing polyester resins, sulfonic acid group-containing polyester resins, and phosphoric acid group-containing polyester resins. Among these, carboxyl group-containing polyester resins are more preferable. The acid value of the acid group-containing polyester resin is preferably 1 to 100, more preferably 5 to 40.

  The carboxyl group-containing polyester resin is necessary, for example, by using the compound (a) having a structure obtained by hydrogenating part or all of the aromatic ring as part or all of the acid component and / or alcohol component. Depending on, for example, dibasic acid or its anhydride, trifunctional or higher polybasic acid, monobasic acid or other acid components, for example, dihydric alcohol, trifunctional or higher alcohol, monohydric alcohol or other alcohol The components can be mixed by a composition ratio in which carboxyl groups remain, and can be prepared by a dehydration condensation method at a reaction temperature of 180 to 260 ° C. while measuring an acid value under heating in a nitrogen atmosphere.

  The apparatus used for the preparation of the neutralized acid group-containing polyester resin or acid group-containing polyester resin includes batches such as a reaction vessel equipped with a nitrogen inlet, a thermometer, a stirrer, a rectifying tower, and the like. In addition to the above-described production apparatus, an extruder, a continuous reaction apparatus, a kneader, or the like having a degassing port can also be used. In the dehydration condensation, the esterification reaction can be promoted by reducing the pressure of the reaction system as necessary. Furthermore, various catalysts can also be added to accelerate the esterification reaction.

  Examples of the catalyst include antimony oxide, barium oxide, zinc acetate, manganese acetate, cobalt acetate, zinc oxalate, zinc borate, cadmium formate, lead monoxide, calcium silicate, dibutyltin oxide, butylhydroxytin oxide, tetra Examples include isopropyl titanate, tetrabutyl titanate, magnesium methoxide, sodium methoxide and the like.

  The compound (a) only needs to have a structure obtained by hydrogenating a part or all of the aromatic ring, for example, a compound having a structure obtained by hydrogenating a part or all of the aromatic ring. Even if it is based on another manufacturing method, if it has a structure obtained by hydrogenating a part or all of an aromatic ring, it can be used without trouble. Examples of such a compound (a) include a basic acid (a1) having a structure obtained by hydrogenating part or all of an aromatic ring, or a structure obtained by hydrogenating part or all of an aromatic ring. And alcohol (a2) having

  Examples of the basic acid (a1) include hexahydrophthalic acid and anhydrides thereof, dibasic acids having a cycloalkane structure such as cyclohexanedicarboxylic acid and anhydrides thereof, and anhydrides thereof, and tetrahydrophthalic acid and anhydrides thereof. Etc.

  Examples of the alcohol (a2) include hydrogenated bisphenol A alkylene oxide adduct, 1,4-cyclohexanedimethanol and the like.

  The compound (a) having a structure obtained by hydrogenating a part or all of the aromatic ring is obtained by hydrogenating a part or all of the aromatic ring because an electrophotographic toner having excellent image quality can be obtained. A dibasic acid having a structure and an anhydride thereof are preferable, a dibasic acid having a cycloalkane structure and an anhydride thereof are more preferable, and hexahydrophthalic acid and an anhydride thereof are most preferable.

  The polyester resin (A) is prepared by using 0.1 to 50 parts by weight of the compound (a) having a hydrogenated structure of the aromatic ring with respect to 100 parts by weight of the total raw material of the polyester resin (A). The obtained polyester resin is preferable, the polyester resin obtained by using 0.5 to 20 parts by weight is more preferable, and the polyester resin obtained by using 1.0 to 10 parts by weight is most preferable.

  The compound (a) having the aromatic ring hydrogenated structure may be used alone or in combination of two or more.

  Examples of the dibasic acid having a neutralized acid group include sulfoterephthalic acid, 3-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and sulfo-p. -Metal salts such as sodium salts such as xylylene glycol and 2-sulfo-1,4-bis (hydroxyethoxy) benzene, potassium salts, calcium salts, barium salts, and zinc salts.

  Examples of the dibasic acid and anhydride thereof include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, succinic acid, malonic acid, succinic acid, succinic anhydride, dodecyl succinic anhydride, and dodecyl anhydride. Linear aliphatic dibasic acids such as succinic acid, dodecenyl succinic acid, dodecenyl succinic anhydride, adipic acid, azelaic acid, sebacic acid, decane-1,10-dicarboxylic acid; phthalic acid, tetrahydrophthalic acid and its anhydride, Hexahydrophthalic acid and its anhydride, tetrabromophthalic acid and its anhydride, tetrachlorophthalic acid and its anhydride, het acid and its anhydride, hymic acid and its anhydride, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid Cycloaliphatic dibasic acids such as 2,6-naphthalenedicarboxylic acid and aroma And the like dibasic acids.

  Examples of the divalent alcohol include ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol. Of diols such as bisphenol A and bisphenol F; aliphatic diols such as diol, dipropylene glycol, triethylene glycol and neopentyl glycol; Bisphenol A alkylene oxide adducts such as ethylene oxide adducts, propylene oxide adducts of bisphenol A; Aralkylene glycols such as xylylene diglycol; 1,4-cyclohexanedimethanol, water And alicyclic diols such as bisphenol A.

  Examples of the tribasic or higher polybasic acid and its anhydride include trimellitic acid, trimellitic anhydride, methylcyclohexentrycarboxylic acid, methylcyclohexentricarboxylic acid anhydride, pyromellitic acid, pyromellitic anhydride, and the like.

  Examples of the monobasic acid include benzoic acid and p-tert-butylbenzoic acid.

  Examples of the tri- or higher functional alcohol include glycerin, trimethylolethane, trimethylolpropane, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, diethylene Examples include pentaerythritol, 2-methylpropanetriol, 1,3,5-trihydroxybenzene, tris (2-hydroxyethyl) isocyanurate and the like.

  Examples of the monovalent alcohol include higher alcohols such as stearyl alcohol.

  The above-mentioned dibasic acid, its anhydride, trifunctional or higher basic acid, its anhydride, monobasic acid, etc. may be used alone or in combination of two or more. Further, those in which part or all of the carboxyl groups are alkyl esters, alkenyl esters or aryl esters can also be used.

  The aforementioned dihydric alcohol, trifunctional or higher functional alcohol, monohydric alcohol and the like may be used alone or in combination of two or more.

  Further, for example, compounds having both a hydroxyl group and a carboxyl group in one molecule such as dimethylolpropionic acid, dimethylolbutanoic acid and 6-hydroxyhexanoic acid or reactive derivatives thereof can be used.

Furthermore, the polyester resin (A) is preferably a polyester resin containing an alkyl group and / or an alkenyl group because an electrophotographic toner having good compatibility with the acrylic resin (B) and good image quality can be obtained. The polyester resin containing an alkyl group or an alkenyl group can be produced, for example, using the following method.
Method 1: In the above-described method for preparing the polyester resin (A), a polyester resin is preferably prepared by using a dibasic acid having an alkyl group or an alkenyl group as an essential component.
Method 2: After obtaining a polyester resin having a carboxyl group at the terminal (may contain a carboxyl group in the main chain) in the preparation method of the polyester resin (A) described above, the polyester resin is heated and melted. Then, an aliphatic monoepoxy compound having an alkyl group or an alkenyl group is added thereto, and ring-opening addition is performed on a part of the terminal carboxyl group of the polyester resin.
Method 3: After obtaining a polyester resin having a hydroxyl group at the end (may contain a hydroxyl group in the main chain) in the preparation method of the polyester resin (A) described above, the polyester resin is heated and melted, A method in which an acid anhydride having an alkyl group or an alkenyl group is added to, and ring-opening addition is added to the terminal hydroxyl group of the polyester resin.

  The alkyl group and alkenyl group may be linear or branched, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, Examples include hexyl group, octyl group, nonyl group, isononyl group, dodecyl group, dodecenyl group and the like. The alkyl group or alkenyl group is preferably an alkyl group having 4 to 20 carbon atoms or an alkenyl group having 4 to 20 carbon atoms.

  Examples of the dibasic acid having an alkyl group or an alkenyl group include dibasic acids such as n-butyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, and anhydrides thereof.

  Examples of the aliphatic monoepoxy compound having an alkyl group or an alkenyl group to be used in the method 2 include various saturated or unsaturated fatty acid monomers such as castor oil fatty acid, coconut oil fatty acid, soybean oil fatty acid, and tung oil fatty acid. Examples thereof include glycidyl esters, cardula E10 (manufactured by Shell Chemical Co., Ltd.), monoglycidyl esters of branched fatty acids such as isononanoic acid and versatic acid.

  Examples of the acid anhydride having an alkyl group or an alkenyl group used in Method 3 include n-butyl succinic anhydride, n-pentyl succinic anhydride, neopentyl succinic anhydride, n-hexyl succinic anhydride, n- Heptyl succinic anhydride, n-octyl succinic anhydride, isooctyl succinic anhydride, 2-ethylhexyl succinic anhydride, n-dodecyl succinic anhydride, n-dodecyl succinic anhydride, isododecyl succinic anhydride, n-dodecenyl succinic acid, n-dodecenyl Examples thereof include succinic anhydride, isododecenyl succinic anhydride, 6-butyl-1,2,4-benzenetricarboxylic acid anhydride, 6-n-octyl-1,2,4-benzenetricarboxylic acid anhydride, and the like. Of these, n-dodecenyl succinic anhydride is preferable.

  Among the polyester resins containing an alkyl group or an alkenyl group, the polyester resin obtained by the method 2 and the polyester resin obtained by the method 3 are more preferable.

  The polyester resin containing an alkyl group or alkenyl group is obtained by using 0.1 to 50 parts by weight of the compound containing an alkyl group or alkenyl group with respect to 100 parts by weight of the total raw material of the polyester resin. Polyester resins are preferred, polyester resins obtained using 0.5 to 20 parts by weight are more preferred, and polyester resins obtained using 1.0 to 10 parts by weight are most preferred.

  The weight average molecular weight of the polyester resin (A) by GPC method is preferably 3,000 to 40,000, and more preferably 5,000 to 35,000. The softening point of the polyester resin (A) by the ring and ball method is preferably 70 to 130 ° C, more preferably 75 to 125 ° C, and most preferably 80 to 120 ° C. 40-75 degreeC is preferable, as for Tg by the differential scanning calorimeter (DSC) of a polyester-type resin (A), 45-70 degreeC is more preferable, and 50-65 degreeC is especially preferable.

  In the present invention, the softening point of the polyester resin (A) is preferably lower than the softening point of the acrylic resin (B) described later, and the softening point of the polyester resin (A) is the acrylic resin ( More preferably, it is 30 to 50 ° C. lower than the softening point of B).

  Examples of the acrylic resin (B) used in the present invention include non-self-water-dispersible acrylic resins that can be dispersed in an aqueous medium by using an emulsifier, a suspension stabilizer, and the like; an emulsifier, a suspension stabilizer, and the like. Examples include acrylic resins that can be dispersed in an aqueous medium without use, and self-water-dispersible acrylic resins such as acrylic resins that can be dispersed in an aqueous medium by neutralization. Based resins are preferred. The acrylic resin (B) is prepared by dissolving the acrylic resin in an organic solvent that can dissolve the acrylic resin at room temperature, such as tetrahydrofuran and methyl ethyl ketone, and then stirring the aqueous resin (non-aqueous) into the resulting resin solution. In the case of a self-water dispersible acrylic resin, an aqueous medium containing an emulsifier, etc. Among the self-water dispersibility, an aqueous medium containing a neutralizing agent in the case of an acrylic resin that can be dispersed in an aqueous medium by neutralization) Is preferably an acrylic resin that can be dispersed and dispersed in the form of particles having an average particle diameter of 10 μm or less by phase inversion emulsification, and an acrylic resin that can be dispersed in a particle form of 0.1 μm or less. Particularly preferred.

  Examples of the self-water dispersible acrylic resin include neutralized acid group-containing acrylic resins such as sulfonic acid metal salts and carboxylic acid metal salts; neutralized basic group-containing acrylic resins; hydroxypolyoxy Hydrophilic segment-containing acrylic resin such as acrylic resin with a so-called nonionic structure such as ethylene; acid base such as carboxyl group, organic base such as alkanolamine, inorganic base such as ammonia and sodium hydroxide An acrylic resin that can be anionized in the aqueous phase by adding a neutralizing agent such as an organic acid, an inorganic acid or the like having a basic group such as an amino group or a pyridine ring Acrylic resins that can be cationized in the aqueous phase by adding an acid group include neutralized acid group-containing acrylic resins and acid group-containing resins. Preferably acrylic resins, are particularly preferred acid group-containing acrylic resin from it easily save a low hygroscopic property.

  Examples of the neutralized acid group-containing acrylic resin include, for example, a neutralized acid group-containing (meth) acrylic resin and a neutralized acid group-containing styrene- (meth) acrylic ester copolymer resin. Among them, a neutralized acid group-containing styrene- (meth) acrylic ester copolymer resin is preferable.

  Examples of the neutralized acid group-containing acrylic resin include, for example, an acrylic resin obtained using a compound having a neutralized acid group as an essential component, an acid group such as a carboxyl group, and neutralization. An acrylic resin obtained by neutralizing an acid group after preparing an acrylic resin to be a self-water dispersible acrylic resin by the above method. Specific examples thereof include neutralized carboxyl group-containing acrylic resins, neutralized sulfone group-containing acrylic resins, neutralized phosphoric acid group-containing acrylic resins, and the like. When using an acrylic resin obtained by using a neutralized acid group-containing compound as an essential component as the self-water dispersible acrylic resin, a neutralized sulfone group-containing acrylic resin is preferable. When an acrylic resin obtained by neutralizing an acid group after preparing an acrylic resin to be a self-water dispersible acrylic resin, a neutralized carboxyl group-containing acrylic resin is preferred. In addition, as an acid value at the time of removing neutralization of the neutralized acid group containing acrylic resin, 1-100 are preferable and 5-40 are more preferable.

  The neutralized acid group-containing acrylic resin is, for example, a monomer having a neutralized group as an essential component, in addition to water containing a dispersant, a surfactant or the like together with other monomers as necessary, Furthermore, it can be prepared by a suspension polymerization method or the like performed by adding a readily soluble polymerization initiator.

  Examples of the acid group-containing acrylic resin include an acid group-containing (meth) acrylic resin, an acid group-containing styrene- (meth) acrylic ester copolymer resin, and the like. -(Meth) acrylic ester copolymer resins are preferred. In addition, as an acid value of acid group containing acrylic resin, 1-100 are preferable and 5-40 are more preferable.

  As the acid group-containing acrylic resin, for example, an acrylic resin obtained by using a compound having an acid group such as a carboxyl group, for example, (meth) acrylic acid as an essential component is preferable. Specific examples of the acrylic resin include a carboxyl group-containing acrylic resin, a sulfonic acid group-containing acrylic resin, and a phosphoric acid group-containing acrylic resin, and among them, a carboxyl group-containing acrylic resin is preferable.

  The carboxyl group-containing acrylic resin is essential for the monomer having a carboxyl group, and if necessary, in addition to water containing a dispersant, a surfactant and the like together with other monomers, is further soluble in the monomer. It can be prepared by a suspension polymerization method or the like performed by adding a polymerization initiator.

  The apparatus used for the preparation of the neutralized acid group-containing acrylic resin or acid group-containing acrylic resin includes batches such as a reaction vessel equipped with a nitrogen inlet, a thermometer, a stirrer, a rectifying tower, and the like. In addition to the above-described production apparatus, an extruder, a continuous reaction apparatus, a kneader, or the like having a degassing port can also be used.

  Examples of the monomer having a neutralized group include sodium salt of (meth) acrylic acid.

  Examples of the monomer having an acid group include (meth) acrylic acid.

  Along with the monomer having a neutralized group and the monomer having an acid group, a (meth) acrylic resin, a neutralized acid group-containing styrene- (meth) acrylic ester copolymer resin, etc. Other monomers that can be used for the preparation of the acrylic resin include, for example, styrene; α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2 Styrene derivatives such as 1,4-dimethylstyrene and pt-butylstyrene; methyl methacrylate derivatives such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate and 2-ethylhexyl methacrylate; methyl acrylate , Ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, Acrylic acid ester derivatives such as isobutyl crylate, n-octyl acrylate, 2-ethylhexyl acrylate; acrylonitrile, methacrylonitrile, acrylamide, N-butyl acrylamide, N, N-dibutyl acrylamide, methacrylamide, N-butyl methacrylamide And (meth) acrylic acid derivatives such as N-octadecylacrylamide. These may be used alone or in combination.

  The weight average molecular weight by the gel permeation chromatography (GPC) method of the acrylic resin (B) is preferably 50,000 to 500,000, more preferably 60,000 to 420,000, and 70,000 to 350,000. Particularly preferred. The softening point of the acrylic resin (B) by the ring and ball method is preferably 120 to 190 ° C, more preferably 135 to 180 ° C, and particularly preferably 140 to 170 ° C. The glass transition temperature (Tg) by DSC of the acrylic resin (B) is preferably 55 to 85 ° C, more preferably 60 to 80 ° C, and particularly preferably 56 to 75 ° C.

  In the electrophotographic toner of the present invention, part or all of the core portion and / or the shell layer is colored. The coloring may be performed to such an extent that it can be used as an electrophotographic toner. For example, the core portion may be colored and the shell layer may not be colored, or the core portion may not be colored and the shell is not colored. Part or all of the layer may be colored, or part or all of the core part and the shell layer may be colored. Among them, the core part is preferably colored. The colored core part or shell layer is made of, for example, a colored acrylic resin or polyester resin obtained by kneading an acrylic resin (B) or polyester resin (A) and a colorant using a pressure kneader or the like. It is obtained by using.

  Examples of the colorant include carbon black, bengara, bitumen, titanium oxide, nigrosine dye (CI No. 50415B), aniline blue (CI No. 50405), calco oil blue (CI No. azoic Blue 3), chrome yellow ( CI No.14090), Ultramarine Blue (CINo.77103), DuPont Oil Red (CINo.26105), Quinoline Yellow (CINo.47005), Methylene Blue Chloride (CINo.52015), Phthalocyanine Blue (CINo.74160) ), Malachite green oxalate (CI No. 74160), malachite green oxalate (CI No. 42000), lamp black (CI No. 77266), rose bengal (CI No. 45435) and the like.

  The colorant is preferably used in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of the acrylic resin (B) or the polyester resin (A). The colorant can be used alone or in combination of two or more.

  The average particle size of the core portion of the electrophotographic toner of the present invention is preferably 1 to 10 μm, and more preferably 2 to 8 μm. Moreover, 0.2-4 micrometers is preferable and, as for the thickness of a shell layer, 0.3-3 micrometers is more preferable.

Next, a method for producing the electrophotographic toner of the present invention will be described. As a preferred method for producing the electrophotographic toner of the present invention, for example, a production method having the following steps may be mentioned.
Step 1. An aqueous dispersion (I) obtained by dispersing resin fine particles (P1) containing the polyester resin (A) in an aqueous dispersion and a resin fine particles (P2) containing an acrylic resin (B). A step of preparing an aqueous dispersion (II) dispersed therein. Here, the resin fine particles (P1) and / or the resin fine particles (P2) are colored by mixing the polyester resin (A) and / or the acrylic resin (B) and the pigment so as to become colored resin fine particles. An aqueous dispersion (I) or an aqueous dispersion (II) is prepared using a resin or an acrylic resin.
Step 2. The aqueous dispersion (I) obtained in the step 1 and the aqueous dispersion (II) are mixed in a combination in which the average particle size of the resin fine particles (P2) is smaller than the average particle size of the resin fine particles (P1). The resin fine particles (P1) and the resin fine particles (P2) are associated to form the resin fine particles (P1) as a core portion, and a shell layer is formed on the surface of the core portion by associating the resin fine particles (P2). Process.
Step 3. A step of recovering the associated fine particles from the dispersion containing the associated fine particles obtained in the step 2 and, if necessary, washing with ion-exchanged water and the like, followed by drying.

The aqueous dispersion (I) and the aqueous dispersion (II) can be produced, for example, by the following method.
Method 1: A resin containing a colored acrylic resin (B) or a resin containing a colored polyester resin (A) is pulverized using a jet mill or the like, classified as necessary, and then an emulsifier and a suspension stabilizer. Or the like, in a water-based medium that may contain the like.
Method 2: As a resin containing a colored acrylic resin (B) or a colored polyester resin (A), a resin containing an acrylic resin containing an acid group or a polyester resin is used. A method in which an organic solvent is mixed to prepare a resin solution in which a resin is dissolved in an organic solvent, and then an aqueous medium containing a basic compound is dropped into the resin solution to perform phase inversion emulsification.

  Among these, the aqueous dispersion (I) and the aqueous dispersion (II) are the above-mentioned because the spherical resin fine particles having a small particle size distribution can be produced, and an electrophotographic toner with good image quality can be obtained. Preferably, it is produced using Method 2. A method for producing the aqueous dispersion (I) and the aqueous dispersion (II) using the method 2 will be described.

  In the method of producing the aqueous dispersion (I) or aqueous dispersion (II) using the above method 2, the acid group-containing polyester resin or acid group-containing acrylic resin used is a carboxyl group-containing polyester resin or carboxyl. A group-containing acrylic resin is preferred. 1-100 are preferable and, as for the acid value of these resin, 5-40 are more preferable.

In order to color the above carboxyl group-containing acrylic resin or carboxyl group-containing polyester resin, a pigment, and if necessary, a charge control agent, a release agent, etc., are heated kneader, heated three rolls, twin screw extrusion kneader. Etc. are used to obtain a kneaded product, and the kneaded product is mixed with an organic solvent such as tetrahydrofuran or methyl ethyl ketone to obtain a resin solution in which the resin is dissolved in the organic solvent. The mixing ratio of the organic solvent in the kneaded product at this time is usually 5 to 300 parts by weight with respect to 100 parts by weight of the kneaded product.

  Next, an aqueous medium containing a basic compound is added dropwise to the resin solvent with stirring to perform phase inversion emulsification. Examples of the basic compound used herein include alkali compounds such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, carbonates thereof, acetates thereof, ammonia water, methylamine, dimethylamine, Examples thereof include alkylamines such as trimethylamine, ethylamine, diethylamine and triethylamine, and alkanolamines such as diethanolamine. Among these, aqueous ammonia is preferable. These basic compounds may be used alone or in combination of two or more.

  The amount of the basic compound used is not limited as long as it is an amount that stably disperses the acrylic resin (B) or the polyester resin (A) in the aqueous medium, but with respect to the acid groups in the resin, Usually 0.5 to 6.0 times equivalent.

  The usage-amount of an aqueous medium is 70-400 weight part normally with respect to 100 weight part of resin solutions. The dropping speed of the aqueous medium is usually 10 to 800 parts by weight per minute.

  Agitation at the time of phase inversion emulsification can be performed using, for example, a turbine blade. The stirring speed is usually 300 to 10,000 rpm.

  After completion of phase inversion emulsification, the organic solvent may be removed. Examples of the method for removing the organic solvent include vacuum distillation.

  The average particle diameter of the resin fine particles in the aqueous dispersion (I) is preferably 1 to 10 μm, and more preferably 2 to 8 μm. Further, the resin fine particles (P1) in the aqueous dispersion (I) are prepared by dispersing the resin fine particles containing the polyester resin (A) in an aqueous medium, and then preparing the aqueous dispersion. After preparing an aqueous dispersion obtained by dispersing association fine particles obtained by associating resin fine particles therein and resin fine particles containing a polyester resin (A) in an aqueous medium, the aqueous dispersion and colorant particles are prepared. An aqueous dispersion and / or an aqueous dispersion of colored resin fine particles are mixed to obtain a mixed dispersion, and the resin fine particles, the colorant particles and / or the colored resin containing the polyester resin (A) in the mixed dispersion are mixed. The associated fine particles obtained by associating with the fine particles are preferred. For the association, for example, a method for performing association between the resin fine particles (P1) and the resin fine particles (P2) described later can be used.

  When the aqueous dispersion containing the association fine particles is produced, it is preferable to heat at the glass transition temperature (Tg) of the acrylic resin (B) to the glass transition temperature + 50 ° C. during the association. It is more preferable to heat under pressure of up to 1.0 MPa (gauge pressure).

  The aqueous dispersion of the colorant particles or the aqueous dispersion of colored resin fine particles produced separately is not particularly limited as long as the colorant particles or the colored resin fine particles are finely dispersed in the aqueous medium. However, examples thereof include an aqueous dispersion obtained by emulsifying a colorant using a surfactant and the like, an aqueous dispersion obtained by heating and melting a colorant and a resin, and then dispersing in water containing the dispersant. The concentration of the colorant particles and the colored resin particles in these aqueous dispersions is preferably 5 to 10 times the colorant concentration of the target toner.

  The average particle size of the resin fine particles containing the acrylic resin (B) used in preparing the aqueous dispersion containing the association fine particles is preferably 0.05 to 0.8 μm, more preferably 0.08 to 0.5 μm. Preferably, 0.1 to 0.4 μm is particularly preferable.

  The average particle size of the resin fine particles (P2) in the aqueous dispersion (II) is preferably from 0.03 to 1.0 μm because it is easy to form a shell layer, more preferably from 0.08 to 0.5 μm, 2 to 0.4 μm is more preferable.

  Next, by performing association in the step 2, the resin fine particles (P1) are used as core particles, and a shell layer formed by associating the resin fine particles (P2) on the surface of the core particles is formed. Here, “meetings” will be described. In general, resin fine particles in an aqueous dispersion of resin fine particles obtained by the above-described production method and the like are stably present in an aqueous medium without aggregation due to electrostatic repulsion derived from the surface charge. The attractive force works between the resin particles by the Delwars force. Therefore, if the surface charge of the resin particles is appropriately reduced by some action, the attractive force becomes larger than the electrostatic repulsive force, and the resin fine particles start to aggregate to form a dispersion of resin particles grown to a larger particle diameter. This is called a meeting in the present invention. Of the glass transition temperature of the acrylic resin (B) and the glass transition temperature of the polyester resin (A), the temperature of this association is preferably the lower glass transition temperature (Tg) to the glass transition temperature + 50 ° C. More preferably, heating is performed under a pressure of ˜1.0 MPa (gauge pressure). The time required for the meeting is usually 2 to 12 hours, preferably 4 to 10 hours. The association may be performed under stirring, preferably under gentle stirring, for example, stirring with an anchor blade at a rotational speed of about 10 to 100 rpm.

  Examples of the method for reducing or eliminating the surface charge of the resin particles include, for example, a method of adding an acid such as dilute hydrochloric acid, dilute sulfuric acid, acetic acid, formic acid, and carbonic acid as a so-called reverse neutralizer, sodium chloride, potassium chloride, aluminum sulfate. , Salting out by adding metal salts such as ferric sulfate and calcium chloride and metal complexes such as calcium, aluminum, magnesium and iron. In addition, a surfactant may be used as necessary for the purpose of dispersing the colorant or the like in the association step and controlling the progress of the association.

  Examples of the surfactant include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and sodium alkyldiphenyldisulfonate, cationic surfactants such as trimethylstearyl ammonium chloride, and alkylphenoxypoly (ethyleneoxy). Nonionic surfactants such as ethanol can be used, and can be appropriately selected and used.

  The mixing ratio [(I) / (II)] of the aqueous dispersion (I) and the aqueous dispersion (II) in the step 2 is preferably 1 to 5, more preferably 1.5 to 4 in terms of the solid content. preferable.

  When forming a shell layer formed by associating resin fine particles (P2) on the surface of the core particle, the association is preferably performed so that the thickness of the shell layer is 0.2 to 4 μm. It is more preferable to perform the association so as to be 3 to 3 μm.

  Examples of the method for recovering the particles having the core-shell structure obtained in Step 3 include filtration. Drying may be performed by leaving it to stand at room temperature for natural drying, or using a dryer at a temperature that does not affect the performance of the electrophotographic toner, for example, about 50 ° C.

  In the electrophotographic toner of the present invention, additives such as magnetic powder and wax may be used as necessary. An electrophotographic toner containing these is prepared by kneading with the acrylic resin (B) or polyester resin (A) in advance to obtain a kneaded product, and using an aqueous dispersion using these kneaded products. I can do it. These additives may be used alone or in combination of two or more.

  Examples of the magnetic powder include simple metals such as magnetite, ferrite, cobalt, iron, nickel, and alloys thereof.

  Wax can be used as an anti-offset agent for electrophotographic toners. Examples of the wax include synthetic waxes such as polypropylene wax, polyethylene wax, Fischer-Trofisch wax, stearyl bisamide, and oxidized wax, and natural waxes such as carnauba wax and rice wax.

  Further, when a charge control agent is used, a toner having good charging characteristics can be obtained. Examples of the charge control agent include positive charges such as nigrosine-based electron donating dyes, naphthenic acid, higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salts, alkylamides, metal complexes, pigments, and fluorination activators. Control agents, negative charge control agents such as electron-accepting organic complexes, chlorinated paraffins, chlorinated polyesters, sulfonylamines of copper phthalocyanine, and the like.

In the present invention, the ratio of the nonvolatile content in the aqueous dispersion (I) and the aqueous dispersion (II) is determined by leaving the aqueous dispersion in a vacuum dryer at 100 ° C., 0.1 KPa, 3 hours, It calculated | required from the weight change of the said aqueous dispersion. The average particle size of the resin fine particles is 0.001 to 2 μm, the average particle size is measured using a MICROTRAC UPA150 manufactured by Lees + Northrup, and the average particle size of 1 to 40 μm is measured using a Multisizer ^TM 3 manufactured by Beckman Coulter. And measured.

  Hereinafter, the present invention will be specifically described with reference to synthesis examples, examples and comparative examples. Parts and% in the examples are based on weight unless otherwise specified.

Synthesis Example 1 [Synthesis of polyester resin (A)]
Into a 3 L stainless steel flask equipped with a stirrer, nitrogen gas inlet, thermometer and rectifying column, 326 parts of ethylene glycol and 548 parts of neopentyl glycol were charged, the temperature was raised to 140 ° C., and 1.0 part of dibutyltin oxide was added. Then, after confirming that the inside of the system can be uniformly stirred, 1,313 parts of terephthalic acid and 315 parts of isophthalic acid were gradually added. Next, while continuing stirring, the temperature was raised to 195 ° C. over 3 hours, and then the temperature was raised to 245 ° C. over 10 hours. The reaction was further carried out at the same temperature for 8 hours, and after confirming that the acid value was 8 or less, the temperature was lowered to 200 ° C. 56 parts of hexahydrophthalic anhydride was added and reacted for 1 hour, acid value was 17.6, softening point by ring and ball method was 106 ° C, Tg by DSC was 57 ° C, MPC by GPC method was 4,200, and Mw was A polyester resin of 9,200 was obtained. This is designated as polyester resin 1. Polyester resin 1 was dissolved in tetrahydrofuran, water containing ammonia as a neutralizing agent was added thereto, and phase inversion emulsification was carried out to disperse the particles in an average particle size of 0.1 μm or less.

Synthesis Example 2 [Synthesis of acrylic resin (B)]
In a 5 L stainless steel autoclave equipped with a plate valve and a turbine blade, 50 parts by volume of water, 50 parts by volume of a 1% aqueous solution of polyvinyl alcohol having a saponification degree of 85 mol% and a polymerization degree of 2,000, 638 parts of styrene, 16 parts of methacrylic acid, 283 parts of methyl methacrylate, 63 parts of n-butyl acrylate and 4.7 parts of benzoyl peroxide were charged, and the temperature was raised to 120 ° C. with stirring at 700 rpm, and polymerization was carried out for 2 hours. Next, the temperature was lowered to 90 ° C., a horizontal condenser was attached to the autoclave, and distillation was performed at normal pressure for 3 hours in a state where the gas phase of the autoclave was replaced with nitrogen gas. The contents are taken out from the autoclave, and the contents are drained by a nylon net, and then dried in a fluid dryer to have an acid value of 9.8 mg KOH / g, a softening point by ring-ball method of 163 ° C., and a Tg by DSC of 67. A polymer having a Mn of 15,300 and a Mw of 185,000 by the GPC method at 0 ° C. was obtained. This is designated as styrene-acrylic resin 1. Acrylic resin 1 was dissolved in tetrahydrofuran, water containing ammonia as a neutralizing agent was added thereto, and phase inversion emulsification was carried out to disperse the particles in an average particle size of 0.1 μm or less.

Synthesis Example 3 (Synthesis of polyester resin for comparison)
A 3 L stainless steel flask equipped with a stirrer, a nitrogen gas inlet, a thermometer and a rectifying column was charged with 293 parts of ethylene glycol, 418 parts of neopentyl glycol and 15 parts of trimethylolpropane, and the temperature was raised to 140 ° C. 1.0 part was added, and after confirming that the inside of the system could be uniformly stirred, 1,366 parts of terephthalic acid was gradually added. Next, while continuing stirring, the temperature was raised to 195 ° C. over 3 hours, and then the temperature was raised to 245 ° C. over 10 hours. Further, the reaction was carried out at the same temperature for 6 hours. The acid value was 18.2 mgKOH / g, the softening point by ring ball method was 106 ° C., the Tg by DSC was 58 ° C., the Mn by GPC method was 4,400, and the Mw was 9,500. A polyester resin was obtained. This is designated as polyester resin 2. Polyester resin 2 was dissolved in tetrahydrofuran, and water containing ammonia as a neutralizing agent was added thereto and phase-inverted and emulsified to disperse in an average particle size of 0.1 μm or less.

Reference Example 1 [Preparation of aqueous dispersion (I) of polyester resin]
Charge 100 g of polyester resin 1 and 100 g of THF into a 2 L glass autoclave with a propeller blade, pre-pressurize to 0.2 MPa with nitrogen gas, and heat the system until the temperature reaches 90 ° C. while rotating the propeller blade at 100 rpm did. At this time, the pressure in the autoclave was increased to 0.45 MPa. After the inside of the system reached 90 ° C., the rotation speed of the propeller blade was increased to 900 rpm and stirred for 10 minutes to obtain a resin solution. Thereafter, 400 g of an aqueous medium preliminarily heated to 90 ° C. consisting of 3.2 g of 25% ammonia water and 396.8 g of ion-exchanged water is injected under pressure for 5 minutes, and the emulsion in which the polyester resin is dispersed in the form of fine particles in water. An initial aqueous dispersion of color was obtained. The neutralization rate at this time was 150 mol%. The initial aqueous dispersion obtained while continuing stirring was cooled with water to 30 ° C and taken out, and THF was distilled off using a rotary evaporator at 47 ° C for 30 minutes. This dispersion had a nonvolatile content of 25%, a volume average particle size of 0.24 μm, and a particle size distribution of 2.2.

  A glass 2L autoclave equipped with an anchor blade, condenser, nitrogen gas inlet and thermometer was charged with 100 g of the obtained aqueous dispersion and 10 g of acetone while rotating the anchor blade at 50 rpm at room temperature. A mixture of 20 g of 1% dilute hydrochloric acid, 20 g of 1% aqueous calcium chloride solution and 20 g of 1% aqueous sodium dodecylbenzenesulfonate was added dropwise over 30 minutes. Thereafter, the temperature in the system was increased to 80 ° C. over 1 hour, and further association was performed at the same temperature for 5 hours to obtain an aqueous dispersion containing spherical colored particles having an average particle diameter of 4 μm. This is abbreviated as polyester resin fine particle aqueous dispersion 1. This dispersion had a nonvolatile content of 25% and a particle size distribution of 2.2.

Reference Example 2 [Preparation of aqueous dispersion of polyester resin for comparison]
A polyester resin fine particle aqueous dispersion 2 was prepared in the same manner as in Reference Example 1 except that 100 g of polyester resin 2 was used instead of 100 g of polyester resin 1. Polyester resin fine particle aqueous dispersion 2 had a nonvolatile content of 25%, an average particle size of 4 μm, and a particle size distribution of 2.2.

Reference Example 3 [Preparation of Aqueous Dispersion (I) of Acrylic Resin (B)]
49 g of styrene-acrylic resin 1, 30 g of Regal 330 (carbon black manufactured by Cabot), 9 g of Viscol 550P (polypropylene wax manufactured by Sanyo Chemical Co., Ltd.) and Bontron E-80 (manufactured by Orient Chemical Industries, Ltd.) 12 g of charge control agent) were mixed, mixed with a Henschel mixer, and kneaded with a pressure kneader to prepare a kneaded product. 100 g of the coarsely pulverized product of this kneaded product and 100 g of tetrahydrofuran (THF) are charged into a 2 L glass autoclave equipped with a propeller blade, pre-pressurized to 0.2 MPa with nitrogen gas, and the inside of the system is rotated while rotating the propeller blade at 100 rpm. Heated to 90 ° C. At this time, the pressure in the autoclave was increased to 0.45 MPa. After the inside of the system reached 90 ° C., the rotation speed of the propeller blade was increased to 900 rpm and stirred for 10 minutes to obtain a resin solution. Thereafter, 400 parts of an aqueous medium preliminarily heated to 90 ° C. consisting of 1.5 g of 25% ammonia water and 398.5 g of ion-exchanged water was injected under pressure over 5 minutes, and the milk in which the polyester resin was dispersed in water in the form of fine particles A cloudy initial aqueous dispersion was obtained. The neutralization rate at this time was 150 mol%. The initial aqueous dispersion obtained while continuing stirring was cooled with water to 30 ° C and taken out, and THF was distilled off using a rotary evaporator at 47 ° C for 30 minutes. This dispersion had a nonvolatile content of 25%, a volume average particle size of 0.23 μm, and a particle size distribution of 2.4.

Example 1
A glass 2L autoclave equipped with an anchor blade, condenser, nitrogen gas inlet and thermometer was charged with 100 g of acrylic resin fine particle aqueous dispersion 1, 52 g of polyester resin fine particle aqueous dispersion 1, and 10 g of THF. While rotating the anchor blade at 50 rpm at room temperature, a mixture of 20 g of 1% dilute hydrochloric acid, 20 g of 1% aqueous calcium chloride and 20 g of 1% aqueous sodium dodecylbenzenesulfonate was added dropwise over 30 minutes. Thereafter, the temperature in the system is increased to 80 ° C. over 1 hour, and the association is further performed at the same temperature for 5 hours. The acrylic resin fine particles are used as core particles, and the polyester resin fine particles are associated with the surface of the core particles. Resin particles having a core-shell structure having the obtained shell layer were obtained. THF was distilled off using a rotary evaporator at 47 ° C. for 60 minutes, and the dispersion was washed with ion-exchanged water three times, separated from water and dried to obtain resin fine particles. When the volume average particle size and particle size distribution of the resin particles were measured, the volume average particle size was 5.9 μm and the particle size distribution was 1.7. Toner 1 was prepared by mixing 0.3% Aerosil R-974 (Nippon Aerosil Silica) and Henschel mixer with respect to the weight of the resin fine particles. Evaluation of image quality and durability obtained using this toner were carried out by the following methods. The results are shown in Table 1.

Image evaluation method: Toner 1 is loaded into an electrophotographic copier “U-Bix5000” (manufactured by Konishi Roku Photo Industry Co., Ltd.), and a test chart for A4 color (No. 5-1) published by the Electrophotographic Society of Japan is used. The resolution of 1 dot line when a 1200 dpi image was formed was evaluated according to the following judgment.
A: A complete 1 dot line is formed.
○: An almost complete 1 dot line is formed.
X: An incomplete 1 dot line is formed.
XX: 1 dot line is not formed.

Durability Evaluation Method: Toner 1 was stirred on a ball mill frame at 100 rpm for 60 minutes, and the charge amount Q ₆₀ (μq / g) was measured. This was allowed to stand for 3 days at 25 ° C. and a relative humidity of 60%, and then the charge amount Q (μq / g) was measured again. The charge amount decay rate (Q / Q ₆₀ ) × 100 (%) was determined and evaluated as durability. It shows that it is excellent in durability, so that this value is high.
○: 85% or more △: 70% or more and less than 85% ×: less than 70%

Comparative Example 1
A comparative toner 1 'was obtained in the same manner as in Example 1 except that 52g of the polyester resin fine particle aqueous dispersion 1' was used instead of 52g of the polyester resin fine particle aqueous dispersion 1. Evaluation of an image obtained using this toner was performed in the same manner as in Example 1, and the results are shown in Table 1.

  The electrophotographic toner of the present invention has good image quality and excellent durability, and can be suitably used as a color toner as well as a black toner. In addition, the method for producing an electrophotographic toner of the present invention can easily produce an electrophotographic toner having good image quality and excellent durability.

Claims (10)

  A core part composed of resin fine particles containing a polyester resin (A) obtained by using a compound (a) having a structure obtained by hydrogenating a part or all of an aromatic ring as a raw material, and the surface of the core part And a shell layer containing an acrylic resin (B).   The polyester resin (A) is a polyester resin obtained by using 1 to 10 parts by weight of the compound (a) with respect to a total of 100 parts by weight of the raw material of the polyester resin (A). Toner for electrophotography.   The electrophotographic toner according to claim 1, wherein the compound (a) is a dibasic acid having a cycloalkane structure and / or an anhydride thereof.   2. The electrophotographic toner according to claim 1, wherein the dibasic acid having a cycloalkane structure is hexahydrophthalic acid.   5. The electrophotographic toner according to claim 1, wherein the core part has an average particle diameter of 1 to 10 μm and the shell layer has a thickness of 0.2 to 4.0 μm.   Dispersing resin fine particles (P1) containing polyester resin (A) obtained using compound (a) having a structure obtained by hydrogenating a part or all of aromatic rings as a raw material in an aqueous dispersion. An aqueous dispersion (I) obtained by dispersing the resin fine particles (P2) containing the acrylic resin (B) and having an average particle size smaller than the average particle size of the resin fine particles (P1) in an aqueous medium. The dispersion (II) is mixed and the resin fine particles (P1) and the resin fine particles (P2) are associated to form the resin fine particles (P1) as core particles, and the resin fine particles (P2) are associated on the surface of the core particles. A method for producing a toner for electrophotography, comprising forming a shell layer formed as described above.   The method for producing an electrophotographic toner according to claim 6, wherein the compound (a) is a dibasic acid having a cycloalkane structure and / or an anhydride thereof.   The electrophotographic toner according to claim 7, wherein the dibasic acid having a cycloalkane structure is hexahydrophthalic acid.   The method for producing an electrophotographic toner according to claim 6, wherein the resin fine particles (P1) have an average particle diameter of 1 to 10 μm, and the resin fine particles (P2) have an average particle diameter of 0.08 to 0.5 μm.   The aqueous dispersion (I) and the aqueous dispersion (II) are mixed, the resin fine particles (P1) and the resin fine particles (P2) are associated with each other, and the resin fine particles (P1) are used as core particles. 10. The method for producing an electrophotographic toner according to claim 6, wherein a shell layer having a thickness of 0.2 to 4.0 [mu] m formed by associating resin fine particles (P2) on the surface is formed.