JP2004295105A - Toner, method for manufacturing toner, image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner and a method for manufacturing a toner by which stability of a charge amount of a toner using a polyester resin formed from resin particles dispersed in an aqueous medium is improved, and to provide an image forming method and an image forming apparatus. <P>SOLUTION: The toner is obtained through a step of aggregating resin particles in an aqueous medium. The toner is obtained as follows: a resin solution prepared by dissolving a polyester resin and a styrene-acrylic resin in an organic solvent is dispersed in an aqueous medium to prepare a dispersion, the organic solvent is removed from the dispersion, and resin particles are aggregated in the aqueous medium. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used for forming an electrophotographic image by a digital method, and in particular, a toner mainly composed of a polyester resin having a small particle size and a uniform particle size distribution, a method for producing the toner, and an image forming method using the toner And an image forming apparatus.

  The mainstream of electrophotographic image formation has now shifted to digital systems. In digital image formation, for example, excellent fine line reproducibility and high resolution are typified by visualizing a small dot image at a level of, for example, 1200 dpi (the number of dots per inch, one inch is 2.54 cm). A small-diameter toner capable of exhibiting image properties is essential.

  As an example of producing such a small-diameter toner, a raw material for a toner such as a polyester resin is dissolved in an organic solvent, the dissolved component is emulsified and dispersed in an aqueous medium, and the resin particles in the emulsified dispersion are dispersed in a toner. A method for producing a toner that aggregates to a size is disclosed (Patent Documents 1 and 2).

  A toner using a polyester resin as a binder (hereinafter, also simply referred to as a polyester resin toner) has an advantage of excellent fixability. However, usually, when a polyester resin toner is applied to an oilless heat fixing device, the degree of crosslinking is controlled to form a high molecular weight component, the modulus of elasticity at the time of melting is increased, and both fixing property and offset resistance are achieved. However, the crosslinked polyester resin is generally insoluble in organic solvents, and it is difficult to achieve uniform emulsification and dispersion of the components in the above-mentioned aqueous medium. That is, even when a partially cross-linked polyester resin is dissolved in an organic solvent and the dissolved component including the gelling component is emulsified and dispersed in an aqueous medium, uniform emulsification and dispersion cannot be achieved, resulting in coarse A toner containing particles is generated, and as a result, an image defect such as a white spot-like transfer drop is generated. This is a fatal defect in a method for producing a toner having a small diameter and a uniform particle size distribution. For this reason, in order to obtain a polyester resin toner having excellent offset resistance from the above-described method of dispersing in a water-based medium, technical development replacing the above-mentioned crosslinked polyester is required.

  As another problem of the polyester resin toner, there is a problem that the charge amount of the toner is apt to decrease, and when used repeatedly, the charge amount is decreased, fog, toner scattering and the like are caused, and it is difficult to use the toner. This is presumably because the polyester resin has functional groups such as -COOH and -OH groups remaining in the chemical structure, which hinders maintenance of stable chargeability. In addition, in the method for producing a toner by dispersing a polyester resin in the above-described aqueous medium, an environment in which a hydroxyl group or a carboxylic acid group in the polyester resin is likely to remain, the toner is not sufficiently stable in charge amount, The above-mentioned problems of fog and toner scattering have not been sufficiently solved.

  On the other hand, the above-mentioned Document 1 describes an example of manufacturing a toner using a polyester resin as a master batch of a pigment dispersion component and using a styrene-acrylic resin in the process of toner formation. The resin component of the obtained toner is predominantly a styrene acrylic resin component, and has no effect on improving the above-described offset resistance and the stability of the charge amount of the polyester resin toner.

Further, as a polyester resin toner produced by a pulverization method, in order to improve the pulverizability of the polyester resin, other resins such as styrene or a styrene acrylic resin having a number average molecular weight of 11,000 or less, up to 30% by mass in the binder resin. The method used is described (Patent Document 3). However, in the above-described method for producing a toner in which a toner is produced from an emulsified polyester resin, a polyester resin and a styrene acrylic resin are freely blended, and the method is applied to the above-described improvement in offset resistance and stability of charge amount. Can not be seen.
JP-A-2002-296839 JP-A-2002-351140 JP-A-2-127657

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic toner which has solved the above-mentioned various problems. That is, it is an object of the present invention to provide a toner using a polyester resin formed from resin particles dispersed in an aqueous medium and having improved toner charge stability, a toner manufacturing method, an image forming method, and an image forming apparatus. Further, the present invention provides a toner using a polyester resin formed from resin particles dispersed in an aqueous medium and having improved offset resistance and stability of fixing characteristics, a method for producing the toner, an image forming method, and an image forming apparatus. That is.

  Further, the present invention provides a toner which has improved image defects such as transfer omission of a toner using a polyester resin formed from resin particles dispersed in an aqueous medium and toner blisters (image defects caused by aggregation of toner). An object of the present invention is to provide a toner mainly composed of a polyester resin having a uniform particle size distribution capable of providing a good digital image, a method for producing the toner, an image forming method, and an image forming apparatus.

  In order to solve the above-mentioned problems, the present inventors have conducted various studies, and as a result, in a dispersion obtained by dispersing a polyester resin in an aqueous medium, resin particles are aggregated to form toner particles (the individual toner constituting the toner). In the formation of particles, styrene-acrylic resin is mixed with polyester resin, and both resins are mixed at a micro level. The inventors have found that it is possible to provide a toner having a uniform particle size distribution by solving insufficient transferability, transfer omission and toner blister, and completed the present invention.

That is, the present invention is achieved by having a configuration described in any one of the following items.
(Claim 1)
A toner obtained through a step of aggregating resin particles in an aqueous medium, wherein the toner is obtained by dispersing a resin solution obtained by dissolving a polyester resin and a styrene acrylic resin in an organic solvent in an aqueous medium. A toner obtained by preparing a dispersion, removing an organic solvent from the dispersion, and aggregating the resin particles in an aqueous medium.
(Claim 2)
A toner obtained through a step of aggregating resin particles in an aqueous medium, wherein the toner is obtained by dispersing styrene acrylic resin particles in an aqueous medium and a dispersion liquid in which polyester resin particles are dispersed in an aqueous medium. A toner obtained by mixing a dispersion liquid and aggregating the polyester resin particles and styrene acrylic resin particles in an aqueous medium.
(Claim 3)
A toner obtained through a step of aggregating resin particles in an aqueous medium, wherein the toner comprises a styrene-based monomer and an acrylate-based monomer in a dispersion obtained by dispersing polyester resin particles in an aqueous medium. And toner particles obtained by coagulating resin particles formed by polymerization in an aqueous medium.
(Claim 4)
The toner according to any one of claims 1 to 3, wherein the main resin in the toner is a polyester resin.
(Claim 5)
The toner according to any one of claims 1 to 4, wherein the content ratio of the polyester resin and the styrene acrylic resin is 1: 0.05 to 1: 0.30 by mass ratio.
(Claim 6)
In a method for producing a toner obtained through a step of aggregating resin particles in an aqueous medium, a dispersion obtained by dispersing a resin solution obtained by dissolving a polyester resin and a styrene acrylic resin in an organic solvent in an aqueous medium is used. A method for producing a toner, comprising: forming an organic solvent from the dispersion; and aggregating the resin particles in an aqueous medium to form toner particles.
(Claim 7)
In a method for producing a toner obtained through a step of aggregating resin particles in an aqueous medium, a dispersion in which polyester resin particles are dispersed in an aqueous medium and a dispersion in which styrene acrylic resin particles are dispersed in an aqueous medium. And mixing the polyester resin particles and the styrene acrylic resin particles in an aqueous medium to form toner particles.
(Claim 8)
In a method for producing a toner obtained through a process of aggregating resin particles in an aqueous medium, a styrene-based monomer and an acrylate-based monomer are added to a dispersion in which polyester resin particles are dispersed in an aqueous medium. And a process for aggregating resin particles produced by polymerization in an aqueous medium to form toner particles.
(Claim 9)
In an image forming method in which an unfixed toner image formed through a uniform charging step, an image exposing step, and a developing step on a photoreceptor is transferred onto a recording material and then fixed, the toner is used as a toner used in the developing step. Item 6. An image forming method using the toner according to any one of Items 1 to 5.
(Claim 10)
In an image forming apparatus for transferring an unfixed toner image formed on a photoreceptor through a uniform charging unit, an image exposing unit, and a developing unit to a recording material and then fixing the unfixed toner image, the toner is used as a toner for the developing unit. Item 6. An image forming apparatus using the toner according to any one of Items 1 to 5.
(Claim 11)
A toner containing a polyester resin and a styrene acrylic resin in toner particles, wherein the ratio of the polyester resin to the styrene acrylic resin is uniform from the inner layer to the outer layer of the toner particles.
(Claim 12)
A toner containing a polyester resin and a styrene-acrylic resin in toner particles, wherein the outer layer of the toner particles contains relatively more polyester resin than the inner layer.
(Claim 13)
A toner containing a polyester resin and a styrene-acrylic resin in toner particles, wherein the outer layer of the toner particles contains relatively more styrene-acrylic resin than the inner layer.

  As is clear from the examples, by using the toner having the constitution of the present invention, the charging property and the anti-offset property of the electrophotographic toner using the polyester resin obtained through the step of coagulating in an aqueous medium as the binder resin are used. In addition, it is possible to provide a good electrophotographic toner capable of improving fixing characteristics and preventing transfer omission and generation of toner blister.

  Hereinafter, the present invention will be described in detail.

  Although the present invention has a step of aggregating the resin particles, the resin particles used for agglomeration in the present invention also include those in a state containing a solvent, for example, a droplet of a resin solution is also included in this. It is included in the category.

  Next, the polyester resin and the styrene acrylic resin used in the present invention will be described.

  The toner of the present invention contains a polyester resin and a styrene acrylic resin as a binder resin. In addition, it is necessary to form a dispersion of resin particles of these polyester resin and styrene acrylic resin in an aqueous medium.

  The polyester resin preferably used in the present invention is formed by a polycondensation reaction using a divalent or higher valent alcohol monomer and a divalent or higher carboxylic acid monomer as described below.

  Here, the polycondensation reaction refers to a reaction in which a compound having a plurality of functional groups repeats a condensation reaction one after another while releasing a low-molecular compound such as water or alcohol to generate a polymer. Examples of commonly known polycondensation reactions include, for example, a reaction between hexamethylenediamine and adipic acid to release water to form a polyamide (66 nylon), or an alcohol from ethylene glycol and terephthalate. To produce polyester (polyethylene terephthalate) with elimination of

  Examples of the dihydric alcohol monomer include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxypropylene (3.3) -2,2-bis (4- (Hydroxyphenyl) propane, polyoxyethylene (2.0) -bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4-hydroxy Phenyl) propane, etherified bisphenols such as polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene Glycol, 1,4-butanediol, 1,4-butenediol, neopen Glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, hydrogenated bisphenol A, etc. can do.

  Examples of the divalent carboxylic acid monomer include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and malonic acid. , N-dodecylsuccinic acid, n-dodecenylsuccinic acid, isododecylsuccinic acid, isododecenylsuccinic acid, n-octylsuccinic acid, n-octenylsuccinic acid, and anhydrides or lower alkyl esters of these acids. Can be.

  In the present invention, a polyhydric alcohol monomer and a polycarboxylic acid monomer can be used.

  Examples of the trihydric or higher polyhydric alcohol monomer include, for example, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4 -Butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxy Methylbenzene and the like can be exemplified.

  Examples of the trivalent or higher polycarboxylic acid monomer include 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4 -Butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1 , 2,7,8-octanetetracarboxylic acid, pyromellitic acid, empole trimer acid, anhydrides or lower alkyl esters of these acids, and the like.

  For the purpose of blocking the polar group at the terminal of the polyester polymer and improving the environmental stability of toner charging characteristics, a monofunctional monomer may be introduced into the polyester. Monofunctional monomers include benzoic acid, chlorobenzoic acid, bromobenzoic acid, parahydroxybenzoic acid, monoammonium sulfobenzoate, monosodium sulfobenzoate, cyclohexylaminocarbonylbenzoic acid, n-dodecylaminocarbonylbenzoic acid Acid, tert-butylbenzoic acid, naphthalenecarboxylic acid, 4-methylbenzoic acid, 3-methylbenzoic acid, salicylic acid, thiosalicylic acid, phenylacetic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, octanecarboxylic acid, lauric acid, stearyl Acids and monocarboxylic acids such as lower alkyl esters thereof, or monoalcohols such as aliphatic alcohols, aromatic alcohols, and alicyclic alcohols can be used.

  The weight average molecular weight of the polyester resin used in the present invention is usually 3,000 or more, preferably 5,000 to 60,000, and more preferably 6,000 to 40,000 from the viewpoint of hot offset resistance. The number average molecular weight is usually 20,000 or less, preferably 1,000 to 10,000, more preferably 2,000 to 8,000.

  The polyester resin used in the present invention may be modified by having a urethane bond in a molecular structure called a urethane-modified polyester. Hereinafter, the urethane-modified polyester will be described.

  Examples of the polyester modified with a urethane bond include a reaction product of a polyester prepolymer (A) having an isocyanate group and an amine (B). Examples of the polyester prepolymer (A) having an isocyanate group include those obtained by polycondensing the above-mentioned polyvalent carboxylic acids and polyhydric alcohols, and further reacting a polyester having an active hydrogen group with a polyisocyanate. Is mentioned.

  Examples of the active hydrogen group possessed by the polyester include a hydroxyl group (alcoholic hydroxyl group and phenolic hydroxyl group), an amino group, a carboxyl group, and a mercapto group. Of these, an alcoholic hydroxyl group is preferable.

  Examples of the polyisocyanate include aliphatic polyisocyanates (such as tetramethylene diisocyanate, hexamethylene diisocyanate, and 2,6-diisocyanatomethylcaproate); alicyclic polyisocyanates (such as isophorone diisocyanate and cyclohexylmethane diisocyanate); and aromatic diisocyanates ( Araliphatic diisocyanates (such as α, α, α ′, α′-tetramethylxylylene diisocyanate); isocyanurates; and the polyisocyanates blocked with phenol derivatives, oximes, caprolactam, etc. And combinations of two or more of these.

  The ratio of the polyisocyanate is from 5/1 to 1 as the equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group from the viewpoint of low-temperature fixing property and hot offset resistance. / 1, preferably 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1.

  The content of the polyisocyanate constituent component in the prepolymer (A) having a terminal isocyanate group is usually 0.5 to 40% by mass, preferably 1 to 30% by mass, and more preferably 2 to 20% by mass. The isocyanate group contained in one molecule in the prepolymer (A) having an isocyanate group is usually at least 1, preferably 1.5 to 3 on average, and more preferably 1.8 to 2.5 on average. It is.

  Examples of the amines (B) include diamines (B1), triamine or higher polyamines (B2), amino alcohols (B3), aminomercaptans (B4), amino acids (B5), and those obtained by blocking amino groups of B1 to B5. (B6) and the like.

  Examples of the diamine (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′dimethyldicyclohexylmethane, diaminecyclohexane , Isophoronediamine, etc.); and aliphatic diamines (ethylenediamine, tetramethylenediamine, hexamethylenediamine, etc.). Examples of the trivalent or higher polyamine (B2) include diethylenetriamine and triethylenetetramine.

  Examples of the amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of the aminomercaptan (B4) include aminoethylmercaptan and aminopropylmercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid.

  Examples of the product obtained by blocking the amino group of B1 to B5 (B6) include ketimine compounds and oxazoline compounds obtained from the amines and ketones (such as acetone, methyl ethyl ketone, and methyl isobutyl ketone) of B1 to B5. Preferred of these amines (B) are B1 and a mixture of B1 and a small amount of B2.

  Further, if necessary, the molecular weight of the urethane-modified polyester can be adjusted using an elongation terminator. Examples of the elongation terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine and the like), and those obtained by blocking them (ketimine compounds).

  The ratio of the amines (B) is defined as the equivalent ratio [NCO] / [NHx] of the isocyanate groups [NCO] in the prepolymer (A) having isocyanate groups and the amino groups [NHx] in the amines (B). , Usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, and more preferably 1.2 / 1 to 1 / 1.2.

  The urethane-modified polyester used in the present invention is produced by a one-shot method or a prepolymer method. The weight average molecular weight of the urethane-modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, and more preferably 30,000 to 1,000,000 from the viewpoint of hot offset resistance.

  The number-average molecular weight of the urethane-modified polyester may be a number-average molecular weight that is easily obtained to obtain the weight-average molecular weight. When the urethane-modified polyester is used alone, the number average molecular weight is usually 20,000 or less, preferably 1,000 to 10,000, and more preferably 2,000 to 8,000 from the viewpoint of low-temperature fixability and glossiness of the toner image. The urethane-modified polyester has a function of improving the particle strength of the toner and has high solubility in a solvent, and is therefore suitable for the present invention.

  The styrene-acrylic resin used in the present invention can be formed by a chain polymerization method using the following styrene-based monomer and acrylate-based monomer, and furthermore, acrylic acid and the like.

  The styrene monomer used as the polymerizable monomer (monomer of the present invention) constituting the resin includes styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α -Methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn Octyl styrene, pn-nonyl styrene, pn-decyl styrene, styrene or styrene derivatives such as pn-dodecyl styrene, and acrylate monomers such as methyl methacrylate, ethyl methacrylate, N-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, Methacrylate derivatives such as n-octyl acrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, acrylic Acrylate derivatives such as isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, and the like; Olefins such as ethylene, propylene and isobutylene; halogenated vinyls such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride and vinylidene fluoride; vinyl propionate; vinyl acetate , Vinyl esters such as vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone, N-vinyl carbazole, N-vinyl indole, N -N-vinyl compounds such as vinylpyrrolidone, vinyl compounds such as vinylnaphthalene and vinylpyridine, and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide. These vinyl monomers can be used alone or in combination.

  Further, it is more preferable to use a combination of those having an ionic dissociation group as the polymerizable monomer constituting the resin. For example, those having a substituent such as a carboxyl group, a sulfonic acid group, or a phosphoric acid group as a constituent group of a monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, and fumaric acid. Acid, monoalkyl maleate, monoalkyl itaconic acid, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxy Propyl methacrylate and the like.

  Furthermore, polyfunctional such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. A resin having a crosslinked structure can be obtained by using a hydrophilic vinyl.

  These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. Examples of the oil-soluble polymerization initiator include 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, and 1,1'-azobis (cyclohexane-1-carbo). Azo or diazo polymerization initiators such as nitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate , Cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,4- t-butylperoxycyclohexyl) propane, tris The (t-butylperoxy) triazine peroxide polymerization initiator or a peroxide, such as and the like polymeric initiator having a side chain.

  When the emulsion polymerization method is used, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and salts thereof, and hydrogen peroxide.

  Dispersion stabilizers include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate , Bentonite, silica, alumina and the like. Further, a surfactant generally used as a surfactant such as polyvinyl alcohol, gelatin, methyl cellulose, sodium dodecylbenzenesulfonate, an ethylene oxide adduct, and higher alcohol sodium sulfate can be used as a dispersion stabilizer.

  As the resin excellent in the present invention, a resin having a glass transition point of 20 to 90 ° C is preferable, and a resin having a softening point of 80 to 220 ° C is preferable. The glass transition point is measured by a differential calorimetric analysis method, and the softening point can be measured by a Koka flow tester. Further, these resins preferably have a number average molecular weight (Mn) of 1,000 to 100,000 and a weight average molecular weight (Mw) of 2,000 to 1,000,000 as measured by gel permeation chromatography. Further, the molecular weight distribution is preferably such that Mw / Mn is 1.5 to 100, particularly 1.8 to 70.

  The styrene-acrylic resin of the present invention may be once dissolved in an organic solvent together with the polyester resin, and the resin solution may be dispersed in an aqueous dispersion medium. A monomer such as an acrylate ester may be dropped, and the polymerization reaction may proceed to form a styrene acrylic resin on the surface of the polyester resin particles.

  In the toner of the present invention, for the purpose of solving the above-mentioned problems of the polyester resin toner obtained by coagulation from the aqueous dispersion medium, the binder resin in the main toner is a polyester resin, and the charge amount of the polyester resin is not sufficient. It can be achieved by mixing a styrene-acrylic resin with a polyester resin in a micro-mixed state in order to improve stability, insufficient offset resistance and the like. The method for stably producing the micro-mixed state is the method for producing a toner according to any one of claims 6 to 8.

  In the toner of the present invention, the ratio of the polyester resin to the styrene acrylic resin is preferably from 1: 0.05 to 1: 0.30 by mass ratio. When the ratio of the styrene-acrylic resin is less than 0.05, the effect of improving the stability of the charge amount of the toner and the anti-offset property and the fixing temperature range is small, and when the ratio is more than 0.30, the high fixing property of the polyester resin is obtained. Not demonstrated.

  As the colorant contained in the toner of the present invention, all known dyes and pigments can be used. Examples of the black pigment used for preparing the black toner include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black. Examples of the magnetic powder include magnetite and ferrite.

  These inorganic pigments can be used alone or in combination of two or more as desired. The content of the inorganic pigment in the toner is preferably from 2 to 20% by mass, more preferably from 3 to 15% by mass.

  When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, the content in the toner is preferably 20 to 120% by mass from the viewpoint of exhibiting predetermined magnetic characteristics.

  As the organic pigment and dye used in the toner according to the present invention, conventionally known organic pigments and dyes can be used, and specific organic pigments and dyes are exemplified below.

  Examples of the magenta or red organic pigment used in the magenta toner include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 and the like.

  Examples of the orange or yellow organic pigment used in the yellow toner include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment Yellow 185, C.I. I. Pigment yellow 155, C.I. I. Pigment Yellow 156 and the like.

  Green or cyan organic pigments used for cyan toner include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

  Examples of the dye include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 and the like. These dyes may be used alone or as a mixture of a plurality of dyes.

  The toner of the present invention may optionally contain a charge control agent. As the charge control agent, any known charge control agent can be used, and examples thereof include a fluorine-based activator, a metal salt of salicylic acid, and a metal salt of a salicylic acid derivative. Specifically, Nigrosine dye Bontron 03, metal-containing azo dye Bontron S-34, oxynaphthoic acid metal complex E-82, salicylic acid metal complex E-84, and phenol condensate E-89 ( Above, manufactured by Orient Chemical Co., Ltd.), TP-302 and TP-415 of quaternary ammonium salt molybdenum complex (above, manufactured by Hodogaya Chemical Co., Ltd.), Copy charge PSYVP2038 of quaternary ammonium salt, triphenylmethane derivative Copy blue PR, quaternary ammonium salt copy charge NEGVP2036, copy charge NX VP434 (all manufactured by Hoechst), LRA-901, boron complex LR-147 (manufactured by Nippon Carlit), other sulfonic acid groups, Polymers having functional groups such as carboxyl groups and quaternary ammonium salts Compounds.

  In the present invention, the charge control agent is preferably used in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin. Preferably, the range is 0.2 to 2 parts by mass.

  The charge control agent is preferably added as a dispersion when emulsified in an aqueous medium.

  In order to give the toner of the present invention a releasability, it is preferable to include a wax in the toner. The wax has a melting point of 40 to 120 ° C., particularly preferably 50 to 110 ° C. in consideration of fixability. The melting point of the wax can be determined by differential scanning calorimetry (DSC). That is, the melting peak value when a few mg of sample is ripened at a constant heating rate, for example (10 ° C./min), is defined as the melting point.

  Examples of the release agent (wax) that can be used in the present invention include solid paraffin wax, micro wax, rice wax, fatty acid amide-based wax, fatty acid-based wax, aliphatic monoketones, fatty acid metal salt-based wax, and fatty acid ester. Wax, partially saponified fatty acid ester wax, silicone varnish, higher alcohol, carnauba wax and the like. Further, polyolefins such as low molecular weight polyethylene and polypropylene can also be used. Particularly, carnauba wax and synthetic ester wax are preferable. These charge control agents and release agents may be melt-kneaded together with the colorant and the binder resin, or added when dissolved and dispersed in an organic solvent. At this time, it is preferable that the fine dispersion is finely dispersed, but for that purpose, a method of precipitating by cooling after heating and dissolving in an organic solvent, or mechanically finely dispersing in an organic solvent by stirring with a medium such as beads. A method is adopted.

  Also, a wax emulsion obtained by heating and stirring and emulsifying the wax in an aqueous medium using a surfactant or a dispersant described later may be prepared, aggregated together with the colored fine dispersion during the aggregation step and blended. good.

As the external additive for assisting the fluidity, developability and chargeability of the colored particles obtained in the present invention, inorganic fine particles can be preferably used. The primary particle diameter of the inorganic fine particles is preferably from 5 nm to 2 μm, and particularly preferably from 5 nm to 500 nm. Further, the specific surface area by the BET method is preferably from 20 to 500 m ² / g. The usage ratio of the inorganic fine particles is preferably 0.01 to 5% by mass of the toner, and particularly preferably 0.01 to 2.0% by mass. Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, and diatomaceous Examples include earth, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

  In addition, polymer-based fine particles, for example, polycondensation systems such as polystyrene, methacrylate and acrylate copolymers obtained by soap-free emulsion polymerization, suspension polymerization, and dispersion polymerization, silicone, benzoguanamine, and nylon, thermosetting Polymer particles made of a resin may be used.

  Such a fluidizing agent can be subjected to a surface treatment to increase hydrophobicity and prevent deterioration of fluidity characteristics and charging characteristics even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate-based coupling agents, aluminum-based coupling agents, silicone oil, modified silicone oil, and the like are preferable surface treatment agents. .

  Examples of the cleaning property improver for removing the developer after transfer remaining on the photoreceptor and the primary transfer medium include, for example, zinc stearate, calcium stearate, fatty acid metal salts such as stearic acid, for example, polymethyl methacrylate fine particles, polystyrene fine particles, and the like. And polymer fine particles produced by soap-free emulsion polymerization. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 10 nm to 1 μm.

  Next, a method for producing the toner of the present invention will be described.

  According to a sixth aspect of the present invention, there is provided a toner manufacturing method obtained by a process of aggregating resin particles in an aqueous medium, wherein a polyester resin and a styrene acrylic resin are dissolved in an organic solvent. The method is characterized in that a dispersion is prepared by dispersing a resin solution in an aqueous medium, an organic solvent is removed from the dispersion, and the resin particles are aggregated in the aqueous medium to form toner particles.

  In preparing a resin solution obtained by dissolving the polyester resin and the styrene acrylic resin in the organic solvent, the polyester resin and the styrene acrylic resin are mixed in the presence of an organic solvent, heated, and melt-dispersed. Is preferred. In this mixing and melting and dispersing step, in addition to the polyester resin and the styrene-acrylic resin, a toner component including a colorant, a charge control agent if necessary, and a release agent is mechanically mixed and melt-dispersed. preferable. As the melting and dispersing machine, stirring with a usual impeller, heat treatment as needed, a ball mill, a sand mill, a homogenizer, and the like can be used.

  Further, a polyester resin and a styrene acrylic resin may be mixed and heated and kneaded. In this mixing and kneading step, in addition to the polyester resin and the styrene-acrylic resin, a toner component and an organic solvent including a colorant, a charge control agent, and a release agent, if necessary, are mechanically mixed and kneaded. Is also good. As the melt kneader, a uniaxial or biaxial continuous kneader or a batch kneader using a roll mill can be used. For example, a KTK twin screw extruder manufactured by Kobe Steel, a TEM extruder manufactured by Toshiba Machine Co., a twin screw extruder manufactured by Kay Kay, a PCM twin screw extruder manufactured by Ikegai Iron Works, Bus A co-kneader or the like is preferably used.

  A resin solution in which a toner component such as a polyester resin, a styrene-acrylic resin, and, if necessary, a colorant is melt-dispersed in an organic solvent by melt-dispersion or melt-kneading by the above method (hereinafter referred to as an oily phase to be a dispersed phase) Or simply referred to as an oily phase).

  Next, the oily phase is emulsified and dispersed in an aqueous medium. At that time, an emulsifying apparatus such as a homomixer (manufactured by Tokushu Kika Co., Ltd.), Ebara Milder (manufactured by Ebara Corporation), and CLEARMIX (manufactured by M Technique) are used. At this time, by controlling the concentration of the emulsifier, the concentration of the toner component with respect to the organic solvent, the amount ratio of the aqueous medium and the oily phase, the number of rotations during emulsification and dispersion, and the time, the oily phase can have a desired droplet diameter and particle size distribution. A dispersed liquid can be obtained. Preferably, the oil phase is emulsified and dispersed to 1/2 to 1/100 of the target toner particle diameter. The mass ratio of the toner component to the organic solvent in the oil phase is preferably selected from 1:10 to 1: 1 and the mass ratio of the aqueous medium to the oil phase is preferably selected from 10: 1 to 1: 1. Of course, it may be outside this range.

  As an aqueous medium, an organic solvent such as water, which can be partially mixed with water, and which can be infinitely diluted, an alcohol such as methanol and ethanol, a ketone such as acetone and methyl ethyl ketone, and an ester such as ethyl acetate is also used in combination with water. be able to.

  The organic solvent for dissolving and dispersing the toner component used for preparing the oily phase is not particularly limited as long as it is insoluble or hardly soluble in water, or partially soluble, and can dissolve the resin constituting the oily phase. Instead, for example, toluene, xylene, benzene, methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, etc. can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and acetates are preferred.

  Dispersion (dispersion of the present invention, hereinafter simply referred to as dispersion, emulsified dispersion) in which an oily phase in which toner components (at least a polyester resin and a styrene acrylic resin) are dispersed is emulsified and dispersed to a desired particle size in an aqueous medium. Examples of the dispersing agent for the production of (ii) include alkylbenzene sulfonates and alkyl sulfates.

  Further, the aqueous medium-dispersed droplets may be stabilized by a polymer-based protective colloid. For example, an acid such as acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride, or a (meth) acrylic monomer containing a hydroxyl group Such as β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-acrylic acid Chloro-2-hydroxypropyl, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerin monoacrylate, glycerin monomethacrylate, N -Methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or esters of vinyl alcohol and compounds containing a carboxyl group, for example, Vinyl acetate, vinyl propionate, vinyl butyrate, etc., acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, pinylpyridine, vinylpyrrolidone, vinylimidazole, ethyleneimine, etc. Homopolymers or copolymers such as those having a nitrogen atom or a heterocycle thereof, polyoxyethylene, polyoxypropylene, Oxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearylphenyl ester, polyoxyethylene nonylphenyl Polyoxyethylenes such as esters and celluloses such as methylcellulose, hydroxyethylcellulose and hydroxypropylcellulose can be used.

  In order to remove the organic solvent from the obtained emulsified dispersion, a method of gradually raising the temperature of the entire system and completely evaporating and removing the organic solvent in the droplets can be adopted. In that case, it is preferable to perform the treatment under reduced pressure since the heating temperature can be reduced. This is to prevent the wax and other toner components from being dissolved in the organic solvent, and to prevent abnormal aggregation, association, and coalescence due to heating of the emulsified dispersion. This step of removing the organic solvent may be performed before or after the aggregation step. If the organic solvent is removed before the aggregation step, fusion and coalescence of the aggregated fine particles can be promoted.

  As another processing method of the solution dissolved in the organic solvent, the emulsified dispersion is sprayed in a dry atmosphere, the water-insoluble organic solvent in the droplet is completely removed to form toner fine particles, and the aqueous dispersion is combined. It is also possible to evaporate off the agent. As the drying atmosphere in which the emulsified dispersion is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide, combustion gas, or the like, in particular, various air streams heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used is generally used. Satisfactory target quality can be obtained by short-time treatment such as spray dryer, belt dryer and rotary kiln.

  As a coagulation method, when the fine particles are dispersed with a charge in water, the electric double layer is compressed by throwing an electrolyte or the like, whereby the particles are aggregated with each other, or particles of a high molecular weight water-soluble polymer are used. By adsorbing and aggregating each other, or by adding a surfactant and a dispersant and a substance that is oppositely charged, the charge on the surface of the fine particles is neutralized and agglomerated. By changing the counter ion of the dispersant, or by adding another substance to the aqueous medium, the solubility of the surfactant or dispersant in the aqueous medium is changed to weaken the dispersion stability and agglomerate. Is done.

  At that time, the above-mentioned wax emulsion or agglomeration with resin fine particles having a polar group is agglomerated to impart releasability at the time of fixing to the produced toner, to enhance the triboelectric charging property, and to increase the glass transition point. By arranging the high resin fine particles relatively outside the toner, it is possible to prevent blocking between the toners at the time of high-temperature storage.

  The coagulant used is, for example, as an electrolyte, sodium sulfate, ammonium sulfate, potassium sulfate, magnesium sulfate, sodium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, ammonium chloride, calcium chloride, cobalt chloride, strontium chloride , Common inorganic or organic water-soluble salts represented by cesium chloride, barium chloride, nickel chloride, magnesium chloride, rubidium chloride, sodium chloride, potassium chloride, sodium acetate, ammonium acetate, potassium acetate, sodium benzoate, etc. Can be used. When a monovalent electrolyte is used, the concentration of these electrolytes is in the range of 0.01 to 2.0 mol / l, more preferably 0.1 to 1.0 mol / l, and even more preferably 0.2 to 0.8 mol / l. preferable. Furthermore, when a polyvalent electrolyte is used, the amount of addition may be smaller. For the surfactant, those exemplified above, and for the polymer-based coagulant, among the above-mentioned ones which form the polymer protective colloid, those of ultrahigh molecular weight are particularly suitable. In addition, as a substance that coexists in an aqueous medium to weaken the dispersion stability and aggregate, it is possible to use water-soluble organic compounds such as ethanol, butanol, isopropanol, ethyl cellosolve, butyl cellosolve, dioxane, tetrahydrofuran, acetone, and methyl ethyl ketone. it can.

  Further, by heating the dispersion after the aggregation, the fine particles are fused together, and the shape of the toner to be formed can be adjusted to a desired degree of sphericity and circularity. The particles are spheroidized by the interfacial tension, and the shape of the particles can be arbitrarily adjusted from spherical to irregular depending on the heating temperature and time (spheronization treatment) at that time.

  Hereinafter, preferable toner shapes of the toner of the present invention will be described.

  As for the shape of the toner according to the present invention, when 2,000 or more toner particles having a particle diameter of 1 μm or more are measured, the average value of circularity (shape coefficient) represented by the following formula is more preferably 0.94 to 0.98. Is 0.94 to 0.97.

Circularity = (perimeter of equivalent circle) / (perimeter of projected image of toner particles)
= 2π × (projected area of particle / π) ^1/2 / (perimeter of projected image of toner particle)
Here, the equivalent circle is a circle having the same area as the projected image of the toner particles, and the equivalent circle diameter is the diameter of the equivalent circle.

  The circularity can be measured by FPIA-2000 (manufactured by Sysmec Corporation). At this time, the circle equivalent diameter is defined by the following equation.

Equivalent circle diameter = 2 × (projected area of particle / π) ^1/2
The shape of the toner of the present invention is such that the average value of the circle equivalent diameter is 2.6 to 7.4 μm, and the inclination of the circularity with respect to the circle equivalent diameter is −0.050 to −0.010. Features. More preferably, the average value of the equivalent circle diameter is 3.4 to 6.6 μm, and the inclination of the circularity with respect to the equivalent circle diameter is −0.040 to −0.020.

  The present inventors developed particles having a large mass and a low circularity on a latent image of a dot as a wedge, and developed particles having a small diameter and a high circularity so as to fill the gap. Adjustment was made so as to be in a filled state. Then, even if dust is generated in the transfer, dust is generated from particles having a small mass, so that it is found that the outline of the dot remains firmly. However, if the circularity and the equivalent circle diameter of the particles are discretely distributed, the effect is insufficient, and there is a problem that selective development and selective transfer are easily caused.

  Accordingly, the concept of changing the degree of circularity continuously with respect to the equivalent circle diameter has been derived to solve the problems of selective development and selective transfer, and found a range in which good fixing performance is exhibited.

  The inclination of the equivalent circle diameter is measured by measuring the equivalent circle diameter of the toner particles with a flow-type particle image analyzer FPIA-2000, and expressing the relationship with the corresponding circularity on the horizontal axis: equivalent circle diameter (μm) -vertical axis. Axis: drawn as a circularity, and looking at its first-order correlation (y = αx + b), α is the slope of the circle equivalent diameter.

At this time, R ² (R 2) is preferably from 0.35 to 0.95 from the viewpoint of improving the uniformity of charging and the uniformity of halftone. Here, R is represented by the following general formula (1).

General formula (1)
R = A / B
In the formula, A and B each represent the following formula.

A = nΣXY- (ΣXΣY)
B = (nΣX ² − (ΣX) ² ) × ((nΣY ² ) − (ΣY) ² )
X represents the equivalent circle diameter (μm), and Y represents the degree of circularity.

  The obtained dispersion liquid of the aggregated particles is sprayed in a dry atmosphere to completely remove the water-insoluble organic solvent remaining in the aggregated particles to form toner particles, and together evaporate the aqueous dispersant. It is also possible to remove it. As a drying atmosphere in which the dispersion liquid of the aggregated particles is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, a combustion gas, etc., in particular, various air flows heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used is generally used. Can be Satisfactory target quality can be obtained by short-time treatment such as spray dryer, belt dryer and rotary kiln. By repeating the operation of solid-liquid separation before drying, addition of washing water, and redispersion (reslurry), most of the used dispersant and emulsifier can be removed.

  When coarse toner particles are present, it is preferable to perform a spheroid operation in a liquid.

  By mixing the resulting dried toner powder with different kinds of particles such as release agent fine particles, charge control fine particles, fluidizing agent fine particles, and colorant fine particles, or by applying a mechanical impact force to the mixed powder. Immobilization and fusion at the surface can prevent the dissociation of foreign particles from the surface of the resulting composite particles.

  As specific means, there are a method of applying an impact force to the mixture by a blade rotating at a high speed, a method of throwing the mixture into a high-speed air flow, accelerating, and colliding particles or composite particles with an appropriate collision plate. is there. As the equipment, Angular Mill (manufactured by Hosokawa Micron), I-type mill (manufactured by Nippon Pneumatic) was modified to reduce the pulverizing air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), Kryptron system (Made by Kawasaki Heavy Industries, Ltd.), automatic mortar, and the like. The above is the description of the aggregation method in the toner manufacturing method according to claim 6.

  The toner produced by the method for producing a toner according to claim 6 is a toner in which the ratio of the polyester resin to the styrene acrylic resin is uniform from the inner layer (including the core) to the outer layer of the toner particles constituting the toner. Can be made.

  8. The method for producing a toner according to claim 7, that is, a method for producing a toner obtained through a step of aggregating resin particles in an aqueous medium, wherein a dispersion of polyester resin particles dispersed in an aqueous medium and styrene in an aqueous medium. A dispersion method in which acrylic resin particles are dispersed is mixed, and the polyester resin particles and styrene acrylic resin particles are aggregated in an aqueous medium to form toner particles. And the subsequent preparation of the dispersion liquid separately produced polyester resin and styrene acrylic resin, then mixed separately prepared dispersion liquid, and added a flocculant to the oil droplets of the mixed oily phase What is necessary is just to aggregate. At this time, toner components other than the resin, such as a colorant and a charge control agent, may be dispersed in the oil phase of the polyester resin or in the oil phase of the styrene acrylic resin. Also, it may be dispersed in both the oily phase of the polyester resin and the styrene acrylic resin.

  The toner produced by the method for producing a toner according to claim 7, wherein after adding the flocculant to the oil droplets of the mixed oily phase, the dispersion stability of the polyester resin particles is higher than that of the styrene acrylic resin particles. Since the styrene-acrylic resin particles are agglomerated first, the polyester resin particles are subsequently agglomerated in the outer layer of the styrene-acrylic resin particle aggregate, and the polyester resin is added to the outer layer in comparison with the inner layer (including the core) of the toner particles. A relatively large amount of toner can be formed.

  In a preferred embodiment of the toner obtained by the method for producing a toner according to claim 7, a polyester resin having a high glass transition point (low softening point) covers a styrene acrylic resin having a low glass transition point (high softening point). It is composed of toner particles. According to this aspect, the toner is more excellent in low-temperature fixability and excellent in offset resistance.

  Further, in the method for producing a toner according to claim 8, ie, a method for producing a toner obtained through a step of aggregating resin particles in an aqueous medium, a styrene-based dispersion liquid in which polyester resin particles are dispersed in an aqueous medium is added. A monomer and an acrylate-based monomer are added, and resin particles formed by polymerization are aggregated in an aqueous medium to form toner particles. As an aggregation method, an oily phase containing a polyester resin is used. The above-mentioned monomers such as styrene and acrylate are dropped into an aqueous dispersion medium (in the above-mentioned dispersion liquid of the present invention) in which the styrene-acrylic resin is dispersed on the surface of the polyester resin particles. Is formed, and then the oil droplets in the dispersion liquid are aggregated to obtain the toner of the present invention. In this case, it is preferable that the toner components other than the resin component, that is, the colorant and the antistatic agent component are mixed and dispersed at the time of preparing the polyester resin dispersion.

  In the toner obtained by the method for producing a toner according to the eighth aspect, toner particles having a form in which a styrene acrylic resin covers a polyester resin are easily obtained. That is, compared to the inner layer (including the nucleus) of the toner particles, a toner in which the outer layer contains a relatively large amount of styrene acrylic resin is easily obtained.

  In the method for producing a toner according to the seventh and eighth aspects, the operations after the step of aggregating the oil droplets of the dispersion liquid may be the same as those in the method for producing the toner according to the sixth aspect.

  Next, a developer using the toner of the present invention will be described.

  When the toner of the present invention is used in a two-component developer, the toner may be mixed with a magnetic carrier. Parts are preferred. As the magnetic carrier, conventionally known ones such as iron powder, ferrite powder, magnetite powder, and magnetic resin carrier having a particle diameter of about 20 to 200 μm can be used. Examples of the coating material include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Further, polyvinyl and polyvinylidene resins, for example, acrylic resins, polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, polystyrene resins such as polystyrene resins and styrene acrylic copolymer resins, polystyrene resins Halogenated olefin resins such as vinyl chloride, polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, polycarbonate resins, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexa Fluoropropylene resin, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and vinyl fluoride, tetrafluoroethylene and vinylidene fluoride Fluoro such as terpolymers of emission and non-fluoride monomers including, and silicone resins. Further, if necessary, a conductive powder or the like may be contained in the coating resin. As the conductive powder, metal powder, carbon black, titanium oxide, tin oxide, zinc oxide and the like can be used. These conductive powders preferably have an average particle size of 1 μm or less. When the average particle size is larger than 1 μm, it becomes difficult to control the electric resistance.

  Further, the toner of the present invention can be used as a one-component magnetic toner or a non-magnetic toner without using a carrier.

  It has been confirmed that the toner of the present invention has high strength of toner particles forming the toner and exhibits strong negative chargeability. From such characteristics, the toner of the present invention is particularly suitable for non-magnetic particles. It is suitable as a component-based developer.

  It is not clear why the toner according to the present invention exhibits such characteristics, but it is presumed to be due to the following reasons.

  First, the toner particles exhibit high strength because the resin particles (or resin solution droplets) are aggregated while being fused at the molecular level during the production of the toner particles. It is presumed that high strength could be developed.

  It is also assumed that the toner particles have a rounded shape close to a sphere, so that even if stress is applied to the toner particles, the stress is appropriately released, so that the toner particles are not broken.

  Next, the reason why strong negative chargeability is obtained is that the resin is made of a strong chargeable resin such as polyester, polyol, or polyurethane, and that the toner particles are easily rotated due to the roundness of the toner particles, resulting in friction. It is presumed that the charging was performed efficiently.

  Further, it has been confirmed that the resin constituting the toner particles according to the present invention easily deforms after aggregation due to its low elastic modulus in an aqueous medium, and exhibits excellent cleaning performance.

  Next, an image forming apparatus for forming an image using the toner according to the present invention will be described.

  FIG. 1 is a schematic view showing an example of the image forming apparatus of the present invention. Numeral 34 denotes a photosensitive drum which is a member to be charged, having a photosensitive layer of an organic photoconductor (OPC) on the outer peripheral surface of a drum base made of aluminum, and rotating at a predetermined speed in the direction of the arrow.

  In FIG. 1, exposure light is emitted from the semiconductor laser light source 31 based on information read by a document reading device (not shown). Exposure light is distributed by the polygon mirror 32 in a direction perpendicular to the paper surface of FIG. 1, and is irradiated on the photoreceptor surface via an fθ lens 33 for correcting image distortion, thereby forming an electrostatic latent image. The photoconductor drum 34 is uniformly charged in advance by a charger (charging means) 35, and starts rotating clockwise in synchronization with the timing of image exposure.

  The exposure is preferably digital image exposure in the present invention, but may be analog image exposure.

  The electrostatic latent image on the surface of the photosensitive drum is developed by a developing device 36, and the formed developed image is transferred to a transfer material 38 conveyed at a proper timing by the operation of a transfer device 37. Further, the photosensitive drum 34 and the transfer material 38 are separated by a separator (separation pole) 39, and the developed image is transferred and carried on the transfer material 38, guided to the fixing device 40, and fixed.

  The untransferred toner and the like remaining on the photoreceptor surface are cleaned by a cleaning device (cleaning means) 41 of a cleaning blade type, and the remaining charge is removed by a pre-charging exposure (PCL) 42, and is charged again for the next image formation. It is uniformly charged by the container 35.

  When the toner of the present invention is used as a non-magnetic one-component developer, a developing device for a non-magnetic one-component developer is used as the developing device 36 in FIG. FIG. 2 is a schematic sectional view showing an example of a developing device used for the non-magnetic one-component developer.

  In FIG. 2, reference numeral 34 denotes a photosensitive drum, 36a denotes a developing roller, 36b denotes a metal elastic blade, 36c denotes a non-magnetic one-component toner, 36d denotes a stirring blade, 36e denotes a recovery plate, and 36f denotes a silicone resin. The developing roller 36a has a surface coated with a silicone resin 36f.

  The present invention can also be used in an image forming apparatus by electrophotography, particularly in an apparatus for forming an electrostatic latent image on a photoreceptor by a modulated beam modulated with digital image data from a computer or the like. FIG. 3 is a schematic configuration diagram showing a digital image forming apparatus that can use the toner according to the present invention.

  In FIG. 3, an image forming apparatus 101 includes an automatic document feeder (ADF) A, a document image reading unit B for reading an image of a document conveyed by the automatic document feeder, and processes the read document image. An image control board C, a writing unit D including a writing unit 112 for writing on a photosensitive drum 34 as an image carrier in accordance with data after image processing, a photosensitive drum 34 and a charger 35, a magnetic brush An image forming unit E including image forming means such as a developing device 36, a transfer device 37, a separator 39, and a cleaning device 41, which are formed by a mold developing device, and a storage unit for paper feed trays 122 and 124 for storing recording paper P. F.

  The main components of the automatic document feeder A include a document placing table 126 and a document feed processing unit 128 including a roller group including a roller R1 and switching means for appropriately switching a document moving path (no reference symbol). .

  The document image reading unit B is located below the platen glass G, and can move back and forth while maintaining the optical path length, two fixed mirror units 130 and 131, a fixed imaging lens (hereinafter simply referred to as a lens) 133, and a line-shaped image sensor. The writing unit D includes a laser light source 31, a polygon mirror (polarizer) 32, and the like.

  When viewed from the direction of movement of the recording paper P as a transfer material, R10 shown on the front side of the transfer unit 37 is a registration roller, and the fixing unit shown at 40 downstream of the separator 39 is a fixing unit.

  In the exemplary embodiment, the fixing unit 40 includes a roller having a built-in heating source, and a pressing roller that rotates while pressing against the roller.

  Further, Z is a cleaning unit for the fixing unit 40, and has a cleaning web provided so as to be wound up as a main element.

  One document (not shown) placed on the document table 126 is transported by the document transport processing unit 128, and is exposed by the exposure unit L while passing under the roller R1.

  The reflected light from the document is imaged on the CCD 135 via the mirror units 130 and 131 and the lens 133 at the fixed position, and is read.

  The image information read by the document image reading unit B is processed by the image processing means, encoded, and stored in a memory provided on the image control board C.

  Further, the image data is called in accordance with the image formation, and the laser light source 31 in the writing section D is driven according to the image data, so that the photosensitive drum 34 is exposed.

  In recent years, in the field of electrophotography, etc., in which an electrostatic latent image is formed on a photoreceptor and this latent image is developed to obtain a visible image, it is easy to improve image quality, convert, edit, etc., and form high quality images. Research and development of image forming methods employing various digital methods have been actively conducted.

  As a scanning optical system that modulates light with a digital image signal from a computer or a copy original used in the image forming method and apparatus, an apparatus that interposes an acousto-optic modulator in a laser optical system and modulates light with the acousto-optic modulator is used. There is a device that directly modulates the laser intensity using a semiconductor laser, and spot-exposes a uniformly charged photoconductor from these scanning optical systems to form a dot-shaped image.

  The beam emitted from the above-described scanning optical system has a round or elliptical luminance distribution approximating a normal distribution with a skirt spreading left and right.For example, in the case of a laser beam, usually, the main scanning direction or on the photosensitive member. One or both of the sub-scanning directions have an extremely narrow round or elliptical shape of 20 to 100 μm.

  The present invention can be applied not only to monochrome images but also to full-color image formation. For example, a plurality of image forming units are provided, and each image forming unit forms a visible image (toner image) of a different color to form a full-color image. And an image forming method for forming a toner image.

  The toner according to the present invention is suitably used in an image forming method including a step of fixing an image forming support on which a toner image is formed by passing the image forming support between a heating roller and a pressure roller constituting a fixing device. You.

  FIG. 4 is a cross-sectional view showing a typical example of a fixing device used in the image forming method using the toner according to the present invention. The fixing device 40 shown in FIG. And a pressure roller 72. T in FIG. 4 is a toner image formed on a transfer paper (image forming support).

  The heating roller 71 has a coating layer 82 made of a fluororesin or an elastic body formed on the surface of a metal core 81, and includes a heating member 75 made of a linear heater.

  The cored bar 81 is made of metal and has an inner diameter of 10 to 70 mm. The metal constituting the metal core 81 is not particularly limited, but examples thereof include metals such as iron, aluminum, and copper, and alloys thereof.

  The core 81 has a thickness of 0.1 to 15 mm, and is determined in consideration of a balance between a demand for energy saving (thinning) and a strength (depending on a constituent material). For example, in order to maintain the same strength as a 0.57 mm iron core with an aluminum core, the thickness of the aluminum core must be 0.8 mm. In particular, it is preferably applied to a fixing roller made of a thin cored bar disclosed in JP-A-2002-189367.

  Specific examples of the fluororesin that forms the coating layer 82 include PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkylvinyl ether copolymer). When a fluororesin is used, the thickness of the coating layer 82 is 10 to 500 μm, preferably 20 to 400 μm.

  Examples of the elastic body for the coating layer 82 include silicone rubber and silicone sponge rubber having good heat resistance such as LTV, RTV, and HTV. The Asker C hardness of the elastic body constituting the coating layer 82 is less than 80 °, preferably less than 60 °. The thickness of the coating layer 82 made of an elastic material is 0.1 to 30 mm, preferably 0.1 to 20 mm.

  As the heating member 75 suitably used as a linear heater, a halogen heater can be used.

  The pressure roller 72 is formed by forming a coating layer 84 made of an elastic body on the surface of a cored bar 83. The elastic body constituting the coating layer 84 is not particularly limited, and examples thereof include various soft rubbers such as urethane rubber and silicone rubber and sponge rubber.

  The elastic material constituting the coating layer 84 has an Asker C hardness of less than 80 °, preferably less than 70 °, and more preferably less than 60 °. The thickness of the coating layer 84 is 0.1 to 30 mm, preferably 0.1 to 20 mm. The material constituting the metal core 83 is not particularly limited, but examples thereof include metals such as aluminum, iron, and copper, and alloys thereof.

  The contact load (total load) between the heating roller 71 and the pressure roller 72 is usually 40 to 350 N, preferably 50 to 300 N, and more preferably 50 to 250 N. The contact load is defined in consideration of the strength of the heating roller 71 (the thickness of the core 81). For example, in the case of a heating roller made of an iron core having a thickness of 0.3 mm, the contact load is set to 250 N or less. It is preferable that

Further, from the viewpoint of offset resistance and fixing property, it is preferable to 4~10mm the nip width, also, the nip surface pressure be ^{0.6 × 10 5 Pa~1.5 × 10 5} Pa preferable.

  The specific fixing conditions in the fixing device shown in FIG. 4 are as follows. For example, good fixing performance is obtained when the fixing temperature (surface temperature of the heating roller 71) is 150 to 210 ° C. and the fixing linear velocity is 230 to 900 mm / sec. Can be

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples. In the following examples, parts and% are based on mass unless otherwise specified.

Example 1
(Preparation of polyester resin 1)
In a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen inlet pipe, 103 parts of a 2 mol adduct of bisphenol A ethylene oxide, 240 parts of a 2 mol adduct of bisphenol A propylene oxide, 133 parts of terephthalic acid, 1,6-hexamethylene 16.5 parts of dicarboxylic acid, 16.5 parts of trimellitic acid and 2 parts of dibutyltin oxide were added, reacted at 230 ° C. for 8 hours under normal pressure, and further reduced under 1.33 to 1.99 Pa (10 to 15 mmHg). After reacting for 5 hours under the following conditions, the mixture was cooled to 110 ° C. to obtain [polyester resin 1] having a number average molecular weight of 3,800, Mw / Mn = 4.0, and a glass transition temperature Tg = 52 ° C.
(Production Example 1 of Toner)
10 parts of a resin composed of a styrene-n-butyl acrylate copolymer (styrene ratio 80% by mass, Mn 12300, Mw / Mn 5.6, Tg 65 ° C)
Polyester resin 1 (polyester resin 1 prepared above) 90 parts Carbon black (MA60 manufactured by Mitsubishi Chemical Corporation) 4.5 parts Pigment Blue 15: 3 0.5 parts Carnauba wax (acid value 1.5, flake form) 5 Part Charge control agent (Bontron E-84, manufactured by Orient Chemical Co.) 2 parts After mixing the above materials with a mixer, 200 parts of ethyl acetate and a sand mill were dissolved and dispersed at 45 ° C. to prepare an oil phase as a dispersed phase.

Separately,
700 parts of ion-exchanged water and 1 part of sodium dodecylbenzenesulfonate were stirred and dispersed to prepare an aqueous phase to be a continuous phase. The oil phase was introduced into the aqueous phase while stirring with a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and the rotation speed of the stirring was adjusted to produce oil droplets having a volume average particle size of about 0.5 μm. Thereafter, ethyl acetate was removed by distillation under reduced pressure at 50 ° C. to obtain a black-gray emulsion. The obtained dispersion was transferred to a stirring tank equipped with an impeller, and an aqueous solution obtained by dissolving 10 parts of aluminum sulfate in 90 parts of ion-exchanged water was slowly dropped while stirring at a low speed to form aggregated particles. Thereafter, stirring was continued at a liquid temperature of 90 ° C., and a part of the coalescence of aggregation was melted and confirmed by a scanning electron microscope. Thereafter, washing and filtration were repeated, and the obtained cake was dried under reduced pressure to obtain black colored particles. 100 parts of the obtained colored particles, 0.8 parts by mass of acicular titanium oxide (major axis: 120 nm, n-decyltrimethoxysilane treatment), spherical monodisperse silica (silica sol obtained by a sol-gel method is treated with hexamethyldisilazane. 1.8 parts by mass of silica having a particle size of 137 nm, which has been dried and pulverized, and 0.3 part by mass of silica (particle size: 14 nm) produced by a gas phase method and treated with octylmethoxysilane, is mixed by a Henschel mixer. The toner 1 was obtained by removing coarse particles and aggregates by passing through a sieve having openings of 50 μm.
(Toner Production Examples 2 to 8)
In the production of the toner 1, electrophotographic toners 2 to 8 were prepared in the same manner except that the amount of the resin composed of the styrene-n-butyl acrylate copolymer and the amount of the polyester resin were changed as shown in Table 1. did. Table 1 shows the resin compositions of the toners 1 to 8, the average value of the toner circularity, and the inclination of the toner circularity.

  After embedding the toner particles of each of the toners 1 to 8 in an epoxy resin, shaving the cross section of the toner particle with a microtome, analyzing the cross section of the toner particle with a time-of-flight secondary ion mass spectrometer (TOF-SIMS). As a result, it was confirmed that the toner particles of each of the toners 1 to 8 had a uniform distribution (existence ratio) of the styrene acrylic resin and the polyester resin from the inner layer to the outer layer of the toner.

Preparation of Developers 1 to 8 Each of the toners 1 to 8 was mixed with 10 parts by mass of the toner and 100 parts by mass of a ferrite carrier having a volume average particle diameter of 55 μm coated with a silicone resin. No. 8 was produced.

Evaluation As the evaluation machine, a Konica “Sitios 7050” digital copier modified with a configuration of FIG. 3 (organic photoreceptor, corona charging, laser exposure, reversal development, electrostatic transfer, nail separation, blade cleaning, Using a heat fixing device, a printing speed: A4 paper 50 sheets / min), and developing materials 1 to 8 mounted on the copying machine were evaluated. The evaluation was performed by copying an original image having a character ratio of 7%, a portrait image of a person, a solid white image, and a solid black image, each of which is equal to ４, on A4 neutral paper. Copying conditions were 100,000 copies each in a high-temperature, high-humidity environment (33 ° C., 80% RH) and a low-temperature, low-humidity environment (10 ° C., 20% RH), and the halftone, solid white image, and solid black image were evaluated. did. The evaluation items and evaluation criteria are shown below.

Environmental Dependence of Image Density Changes in image density due to humidity dependence of charging were investigated. The evaluation was performed with the humidity correction program of the main unit turned off.

  The maximum image density of the solid (solid black) image portion was measured with a Macbeth reflection densitometer. Five measurements were taken at the start of copying and every 50,000 copies, and the evaluation was made based on the difference in image density between the average values of the five measurements.

：: Difference in image density between high temperature and high humidity environment (33 ° C., 80% RH) and low temperature and low humidity environment (10 ° C., 20% RH) is less than 0.05 (good)
：: Difference in image density between high temperature and high humidity environment (33 ° C., 80% RH) and low temperature and low humidity environment (10 ° C., 20% RH) is 0.05 to 0.1 (no problem in practical use)
×: The difference in image density between a high-temperature and high-humidity environment (33 ° C., 80% RH) and a low-temperature and low-humidity environment (10 ° C., 20% RH) is larger than 0.1 (practical problem).
Intra-machine contamination After the 200,000 copies were made, the amount of toner scattered under the developing device was evaluated.

A: Toner scattering is not detected (good)
○: Touching slightly stains hands, but can be used continuously without cleaning (no problem in practical use)
△: Can be used continuously if cleaned with a dry cloth (Maintenance is required to continue)
×: The cloth cannot be wiped off with a dry cloth and is contaminated so that a vacuum cleaner is necessary for cleaning (there is a problem in practical use)
Offset resistance After printing 1000 sheets continuously on A4 size transfer paper, white paper was printed, and the occurrence of stain on the white paper due to offset and toner stain on the heating roller surface of the fixing device were visually evaluated. A thick paper of 200 g / m ² of high quality paper was used as the transfer paper used for the evaluation, and a line image having a width of 0.3 mm and a length of 150 mm parallel to the paper traveling direction (the circumferential direction of the heating roller) was formed. The conditions of the fixing device were set as follows.
(Fixing device conditions)
A heater having a built-in heater in the center, a roller having a surface of a cylindrical aluminum alloy having a diameter of 30 mmφ and a thickness of 2 mm coated with a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA) as a heating roller, having a diameter of 29 mmφ and a thickness of 3 mm Pressurized by coating the surface of a cylindrical aluminum alloy of Example 1 with a sponge-like silicone rubber (Asker C hardness = 48: thickness 8 mm) and further coating a tetrafluoroethylene-perfluoroalkyl ether copolymer (PFA) thereon It has rollers. The nip pressure was 10.8 N / cm ² (total pressure = 194 N) and the nip width was 5.8 mm.

A: Image offset on white paper and toner stain on heating roller are not seen at all (good)
：: No image offset on white paper was observed, but toner contamination was observed on the heating roller (no problem in practical use)
×: Image offset is confirmed on white paper (practical problem)
Fixable temperature region A fixed image was produced while changing the heating roller temperature of the fixing device evaluated for the offset resistance from 130 ° C. to 240 ° C. in steps of 10 ° C. For output of the fixed image, A4 size plain paper (basis weight: 64 g / m ² ) was used.

◎◎: Fixable temperature range is 100 ° C. or higher (very good)
A: less than 100 ° C. and 70 ° C. or more (good)
Good: less than 70 ° C. and 40 ° C. or more (practical use possible)
×: less than 40 ° C. (not practical)
Transfer omission A halftone image with a density of 0.4 was formed on both sides of transfer paper (basis weight 200 g / m ² ), and the occurrence of a white spot due to transfer omission was visually evaluated.

◎◎: No transfer omission (very good)
：: One or two transfer omissions exist only on the back surface per 100 images, but cannot be determined without staring (good)
：: Although there are 1 to 4 transfer omissions per 50 images, they cannot be identified without staring (there is no practical problem).
×: Five or more clear transfer omissions exist on 50 sheets of images regardless of the front / back side (there is a problem in practical use)
Toner Blister An image was formed so that the amount of adhesion on the transfer material was 1.6 m parts by mass / cm ^2, and it was observed whether there was a hole of about 0.1 to 0.5 μm in the image, that is, a toner blister.

：: No toner blister at all ○: 1 to 2 toner blisters per 4 cm ^2, but cannot be identified without staring (no practical problem)
×: Three or more clear toner blisters are present per 4 cm ² (a problem in practical use)
Table 2 shows the evaluation results.

  As is clear from Table 2, the toners 1 to 7 containing the polyester resin having the constitution of claim 1 of the present invention and the styrene-acrylic resin are compared with the toner 8 of the polyester resin having the constitution outside the present invention, It is improved in any evaluation of environmental dependency of image density, in-machine contamination, anti-offset property, fixable temperature range, transfer omission, and toner blister. In particular, when the weight ratio of the styrene-acrylic resin (to the polyester resin) in the toner is in the range of 0.05 to 0.30, the toner No. 1, 3, and 4 have remarkable improvement effects.

Example 2
(Preparation of polyester resin 2)
In a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen introducing pipe, 570 parts of a 2-mol adduct of bisphenol A ethylene oxide and 217 parts of terephthalic acid were reacted at 230 ° C. under normal pressure for 6 hours, and further reacted at 1.33-1. After reacting under reduced pressure of 0.99 Pa (10 to 15 mmHg) for 5 hours, the mixture was cooled to 110 ° C, and [polyester resin 2] having a number average molecular weight of 4,500, Mw / Mn = 4.0, and a glass transition temperature Tg of 60 ° C. Got.
(Production Example 9 of Toner)
50 parts of a resin composed of a styrene-n-butyl acrylate copolymer (styrene ratio 80% by mass, Mn 12300, Mw / Mn 5.6, Tg 65 ° C)
Carbon black (MA60 manufactured by Mitsubishi Chemical Corporation) 2.25 parts Pigment Blue 15: 3 0.25 part Charge control agent (Bontron E-84 manufactured by Orient Chemical Co.) 1 part The above materials are mixed by a mixer and then melted by a two-roll mill. The kneaded product was rolled and cooled. Thereafter, the kneaded material obtained in 100 parts of toluene was dissolved and dispersed in a tank equipped with a stirrer to prepare an oil phase 1 serving as a dispersed phase.

Separately 50 parts of polyester resin 2 (polyester resin 2 prepared above) (acid value 3, hydroxyl value 25, Mn4500, Mw / Mn4.0, Tg60 ° C)
Carbon black (MA60 manufactured by Mitsubishi Chemical Corporation) 2.25 parts Pigment Blue 15: 3 0.25 part Charge control agent (Bontron E-84 manufactured by Orient Chemical Co.) 1 part The above materials are mixed by a mixer and then melted by a two-roll mill. The kneaded product was rolled and cooled. Thereafter, the kneaded material obtained in 100 parts of toluene was dissolved and dispersed in a tank equipped with a stirrer to prepare an oil phase 2 serving as a dispersed phase.

700 parts of ion-exchanged water 1.0 part of sodium dodecylbenzenesulfonate was stirred and dispersed to prepare an aqueous phase to be a continuous phase. The aqueous phase is equally divided into two, an aqueous phase 1 and an aqueous phase 2, and the oil phase 1 is added to the aqueous phase 1 while the aqueous phases are stirred with a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). The styrene-acrylic resin dispersion liquid 1 and the polyester resin dispersion liquid 2 having oil droplets having a volume average particle diameter of about 0.5 μm were prepared by charging the oil phase 2 and adjusting the number of rotations with stirring. Thereafter, both the styrene-acrylic resin dispersion 1 and the polyester resin dispersion 2 were distilled off under reduced pressure at 50 ° C. to remove toluene, thereby obtaining a black-gray styrene-acrylic resin dispersion 1 and a polyester resin dispersion 2. . Subsequently, 1,10 parts of the styrene-acrylic resin dispersion and 90 parts of the polyester resin dispersion are mixed in a stirring tank equipped with an impeller, and 10 parts of aluminum sulfate are added to 90 parts of ion-exchanged water in the tank. Agglomerated particles are formed by slowly dropping the dissolved aqueous solution while stirring at a low speed. Thereafter, the liquid temperature is maintained at 90 ° C., and the mixture is mixed for 6 hours. It was confirmed with a scanning electron microscope. Thereafter, washing and filtration were repeated, and 100 parts of the obtained colored particles, 0.8 part by mass of acicular titanium oxide (major axis: 120 nm, n-decyltrimethoxysilane treatment), and spherical monodisperse silica (obtained by a sol-gel method) The silica sol thus treated is treated with hexamethyldisilazane, dried and pulverized, and is 1.8 parts by mass of silica having a particle size of 137 nm; and silica produced by a gas phase method and treated with octylmethoxysilane (particle size: 14 nm). 3 parts by mass were mixed with a Henschel mixer and passed through a sieve having an opening of 50 μm to remove coarse particles and aggregates, thereby obtaining a toner 9.
(Toner Production Examples 10 to 16)
In the production of the toner 9, electrophotographic toners 10 to 16 were produced in the same manner except that the mixing ratio of the styrene acrylic resin dispersion liquid 1 and the polyester resin dispersion liquid 2 was changed as shown in Table 3. Table 3 shows the resin compositions of the toners 9 to 16, the average value of the toner circularity, and the inclination of the toner circularity.

  After embedding the respective toner particles of the toners 9 to 16 in an epoxy resin and shaving the cross section of the toner particle with a microtome, the cross section of the toner particle is analyzed by a time-of-flight secondary ion mass spectrometer (TOF-SIMS). As a result, it was confirmed that each of the toner particles of the toners 9 to 16 contained more polyester resin in the outer layer relatively than in the inner layer of the toner particles.

Preparation of Developers 9 to 16 The toners 9 to 16 were prepared by mixing 10 parts by mass of the toners 9 to 16 with 100 parts by mass of a ferrite carrier having a volume average particle diameter of 55 μm coated with a silicone resin. No. 16 was produced.

  The same evaluation as in Example 1 was performed using the above-mentioned developers 9 to 16. Table 4 shows the results.

As is clear from Table 4, the toners 9 to 15 containing the polyester resin having the constitution of claim 2 of the present invention and the styrene-acrylic resin are compared with the toner 16 of the polyester resin having the constitution outside the present invention, It is improved in any evaluation of environmental dependency of image density, in-machine contamination, anti-offset property, fixable temperature range, transfer omission, and toner blister. In particular, when the weight ratio of the styrene-acrylic resin (to the polyester resin) in the toner is in the range of 0.05 to 0.30, the toner No. 9, 11, and 12 have remarkable improvement effects.
(Production Example 17 of Toner)
Polyester resin 2 (Polyester resin 2 produced in Example 2) 75 parts Carbon black (MA60 manufactured by Mitsubishi Chemical Corporation) 4.5 parts Pigment Blue 15: 3 0.5 parts Charge control agent (Bontron E-84 manufactured by Orient Chemical Co., Ltd.) 2 parts) The above materials were mixed by a mixer, then melt-kneaded by a two-roll mill, and the kneaded product was rolled and cooled. Thereafter, the kneaded material obtained in 200 parts of toluene was dissolved and dispersed in a tank equipped with a stirrer to prepare an oil phase serving as a dispersed phase.

Separately,
Ion-exchanged water 250 parts Sodium dodecylbenzenesulfonate 3.5 parts Nonylphenol polyethylene oxide 0.035 parts was stirred and dispersed to prepare an aqueous phase which was a continuous phase. The oil phase was introduced into the aqueous phase while stirring with a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and the rotation speed of the stirring was adjusted to produce oil droplets having a volume average particle size of about 0.5 μm. Thereafter, toluene was removed by distillation under reduced pressure at 50 ° C. to obtain a black-gray emulsion. The dispersion was transferred to a 100-liter GL reactor equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a comb baffle, and stirring was started.

  Heating was started, and when the liquid temperature reached 75 ° C., the whole amount of the following polymerization initiator solution A was added dropwise. Thereafter, 13.1 parts of styrene, 5.90 parts of n-butyl acrylate, and 1.00 part of methacrylic acid were added dropwise while controlling the liquid temperature at 75 ° C. ± 1 ° C., and the oil of the dispersion was added. A styrene acrylic polymer was formed on the surface of the polyester particles forming the phase. Subsequently, an aqueous solution obtained by dissolving 10 parts of aluminum sulfate in 90 parts of ion-exchanged water was gradually added dropwise to the dispersion while stirring at a low speed to form aggregated particles. Thereafter, the liquid temperature was maintained at 90 ° C. The coalescence of aggregation was partially sampled and confirmed by a scanning electron microscope. Thereafter, washing and filtration were repeated, and the obtained cake was dried under reduced pressure to obtain black colored particles. 100 parts of the obtained colored particles, 0.8 parts by mass of acicular titanium oxide (major axis: 120 nm, n-decyltrimethoxysilane treatment), spherical monodisperse silica (silica sol obtained by a sol-gel method is treated with hexamethyldisilazane. 1.8 parts by mass of silica having a particle size of 137 nm, which has been dried and pulverized, and 0.3 part by mass of silica (particle size: 14 nm) produced by a gas phase method and treated with octylmethoxysilane, using a Henschel mixer. Then, by passing through a sieve having openings of 50 μm, coarse particles and aggregates were removed to obtain a toner 17.

Polymerization initiator solution A
A solution obtained by mixing a 2% by mass aqueous solution of 22 parts of potassium persulfate and a 2% by mass aqueous solution of ascorbic acid is referred to as a polymerization initiator solution A.
(Production Examples 18 to 24 of Toner)
In the production of the toner 17, electrophotographic toners 18 to 24 were prepared in the same manner except that the amounts of the polyester resin and the amounts of the styrene, n-butyl acrylate and methacrylic acid were changed as shown in Table 5. (However, in the preparation of the toner 24, the polymerization initiator solution A was not added).

  The residual amount of each of the monomers of styrene, n-butyl acrylate and methacrylic acid used in the production of the toners 17 to 24 after polymerization was analyzed by gas chromatography (measured with a dispersion after polymerization). Was 0.01% by mass or less in all the toners. From the results, it was concluded that almost all of the added monomers polymerized to form the styrene acrylic resin in parts by mass shown in Table 5. Conceivable. Table 5 shows the resin compositions of the toners 17 to 24, the average value of the toner circularity, and the inclination of the toner circularity.

  After embedding the toner particles of each of the toners 17 to 24 in an epoxy resin and shaving the cross section of the toner particle with a microtome, the cross section of the toner particle is analyzed by a time-of-flight secondary ion mass spectrometer (TOF-SIMS). As a result, it was confirmed that each of the toner particles of the toners 17 to 24 contained more styrene acrylic resin in the outer layer relatively than in the inner layer of the toner particles.

Preparation of Developers 17 to 24 The toners 17 to 24 were prepared by mixing 10 parts by mass of the toners 17 to 24 with 100 parts by mass of a ferrite carrier having a volume average particle size of 55 μm coated with a silicone resin. 24 were produced.

  The same evaluation as in Example 1 was performed using the above-mentioned developers 17 to 24. Table 6 shows the results.

  As is clear from Table 6, the toners 17 to 23 containing the polyester resin having the constitution of claim 3 of the present invention and the styrene-acrylic resin are compared with the toner 24 of the polyester resin having the constitution outside the present invention, It is improved in any evaluation of environmental dependency of image density, in-machine contamination, anti-offset property, fixable temperature range, transfer omission, and toner blister. In particular, when the weight ratio of the styrene-acrylic resin (to the polyester resin) in the toner is in the range of 0.05 to 0.30, the toner No. 17, 19, and 20 have remarkable improvement effects.

FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. FIG. 3 is a schematic sectional view illustrating an example of a developing device used for a non-magnetic one-component developer. 1 is a schematic configuration diagram illustrating a digital image forming apparatus that can use a toner according to the present invention. FIG. 2 is a cross-sectional view illustrating a representative example of a fixing device used in an image forming method using a toner according to the present invention.

Explanation of reference numerals

34 photosensitive drum 35 charging means 36 developing device 40 fixing device 41 cleaning means

Claims (13)

A toner obtained through a step of aggregating resin particles in an aqueous medium, wherein the toner is obtained by dispersing a resin solution obtained by dissolving a polyester resin and a styrene acrylic resin in an organic solvent in an aqueous medium. A toner obtained by preparing a dispersion, removing an organic solvent from the dispersion, and aggregating the resin particles in an aqueous medium. A toner obtained through a step of aggregating resin particles in an aqueous medium, wherein the toner is obtained by dispersing styrene acrylic resin particles in an aqueous medium and a dispersion liquid in which polyester resin particles are dispersed in an aqueous medium. A toner obtained by mixing a dispersion liquid and aggregating the polyester resin particles and styrene acrylic resin particles in an aqueous medium. A toner obtained through a step of aggregating resin particles in an aqueous medium, wherein the toner comprises a styrene-based monomer and an acrylate-based monomer in a dispersion obtained by dispersing polyester resin particles in an aqueous medium. And toner particles obtained by coagulating resin particles formed by polymerization in an aqueous medium. The toner according to any one of claims 1 to 3, wherein the main resin in the toner is a polyester resin. The toner according to any one of claims 1 to 4, wherein the content ratio of the polyester resin and the styrene acrylic resin is 1: 0.05 to 1: 0.30 by mass ratio. In a method for producing a toner obtained through a step of aggregating resin particles in an aqueous medium, a dispersion obtained by dispersing a resin solution obtained by dissolving a polyester resin and a styrene acrylic resin in an organic solvent in an aqueous medium is used. A method for producing a toner, comprising: forming an organic solvent from the dispersion; and aggregating the resin particles in an aqueous medium to form toner particles. In a method for producing a toner obtained through a step of aggregating resin particles in an aqueous medium, a dispersion in which polyester resin particles are dispersed in an aqueous medium and a dispersion in which styrene acrylic resin particles are dispersed in an aqueous medium. And mixing the polyester resin particles and the styrene acrylic resin particles in an aqueous medium to form toner particles. In a method for producing a toner obtained through a process of aggregating resin particles in an aqueous medium, a styrene-based monomer and an acrylate-based monomer are added to a dispersion in which polyester resin particles are dispersed in an aqueous medium. And a process for aggregating resin particles produced by polymerization in an aqueous medium to form toner particles. In an image forming method in which an unfixed toner image formed through a uniform charging step, an image exposing step, and a developing step on a photoreceptor is transferred onto a recording material and then fixed, the toner is used as a toner used in the developing step. Item 6. An image forming method using the toner according to any one of Items 1 to 5. In an image forming apparatus for transferring an unfixed toner image formed on a photoreceptor through a uniform charging unit, an image exposing unit and a developing unit to a recording material and then fixing the unfixed toner image, the toner used in the developing unit is claimed as Item 6. An image forming apparatus using the toner according to any one of Items 1 to 5. A toner containing a polyester resin and a styrene acrylic resin in toner particles, wherein the ratio of the polyester resin to the styrene acrylic resin is uniform from the inner layer to the outer layer of the toner particles. A toner containing a polyester resin and a styrene-acrylic resin in toner particles, wherein the outer layer of the toner particles contains relatively more polyester resin than the inner layer. A toner containing a polyester resin and a styrene-acrylic resin in toner particles, wherein the outer layer of the toner particles contains relatively more styrene-acrylic resin than the inner layer.

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