JP2006091379A - Method for manufacturing electrophotographic toner, electrophotographic toner, developer, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electrophotographic toner, wherein peeling of a shell layer is prevented to prevent occurrence of fine powder by improving the interfacial strength of the joint interface between the core and the shell while fixing temperature is decreased, and reliability of an image is improved. <P>SOLUTION: In the method for manufacturing an electrophotographic toner by covering the surface of color particles comprising at least a binder resin and a colorant, with an amorphous resin, the binder resin consists of crystalline polyester resin having 50 to 100°C melting point and 12,000 to 50,000 weight average molecular weight. The method includes: an aggregation step of mixing a dispersion liquid of binder resin particles and a dispersion liquid of colorant particles, adding a coagulant to form aggregated particles of the binder resin particles and the colorant particles; a deposition step of depositing amorphous resin particles on the surface of the aggregated particles; a unifying step of unifying the aggregated particles at a temperature equal to or higher than the melting point of the binder resin; and a cooling step of decreasing the temperature down to or lower than the crystallization temperature of the binder resin at a falling rate of at least ≥10°C/minute. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing an electrophotographic toner that can be used in an electrophotographic apparatus utilizing an electrophotographic process such as a copying machine, a printer, and a facsimile, an electrophotographic toner, an electrophotographic developer, and an image forming method.

  Conventionally, as a fixing method of an electrophotographic toner, a pressure fixing method using only a pressure roll at room temperature, a contact heating fixing method using a heating roll, an oven fixing method using oven heating, a flash fixing method using a xenon lamp, etc. Non-contact fixing methods such as electromagnetic wave fixing method using microwaves, solvent fixing method using solvent vapor, etc. are mentioned, but oven fixing method using heat and contact heating type fixing method are mainly from the viewpoint of reliability and safety in use. In particular, the contact heating type fixing method using a heating roll or a belt is usually composed of a heating roll or belt provided with a heating source and a pressure roll or belt, and the toner image surface of the fixing sheet is placed on the heating roll or belt surface. Fixing is carried out by passing through pressure contact, and since the surface of the heated roll or belt and the toner image surface of the fixing sheet are in direct contact, the heat efficiency is effective and fixing can be performed quickly. Have been widely adopted.

  In these thermal fixing methods, the time from when the power is turned on until the temperature of the fixing device quickly rises to the operating temperature and becomes ready for fixing, so-called warm-up time is shortened, and in order to reduce energy consumption It is desired that it can be fixed at a low temperature. Particularly in recent years, it has been desired to stop energization of the fixing machine except during use for thorough energy saving, and the fixing machine temperature needs to reach the fixing possible temperature instantly with energization. Fixing is necessary. In addition, by reducing the fixing temperature, it is possible to increase the printing speed even with the same power consumption, and the contact heating type fixing system can extend the life of the fixing member such as a heating roll. Is also preferable. However, in the conventional method, when the fixing temperature of the toner is lowered, the glass transition point of the toner particles is lowered at the same time, and it is difficult to achieve compatibility with the storage stability of the toner. Therefore, in order to achieve both low temperature fixing and toner storage stability, it is necessary to have a so-called sharp melt property in which the viscosity of the toner rapidly decreases in a high temperature region while keeping the glass transition point of the toner at a higher temperature. is there.

In order to realize such low-temperature fixability, a method using a crystalline resin as a binder resin has been studied. (Patent Document 1, Patent Document 2, Patent Document 3)
By using a crystalline resin, the hardness of the toner is maintained below the melting point of the crystal, and when the melting point is exceeded, the viscosity rapidly decreases as the crystal melts, thereby achieving low-temperature fixing. However, the above disclosed technique, for example, the technique disclosed in Patent Document 1, has a problem in reliability of powder and images because the melting point of the crystalline resin is 62 to 66 ° C. and the melting point is slightly too low.
Further, the crystalline resins described in Patent Documents 2 and 3 have a problem that the fixing performance to paper is not sufficient.

  Examples of the crystalline resin that is expected to improve the fixability to paper include polyester resins. Examples of using a crystalline polyester resin include Patent Document 4, Patent Document 5, and Patent Document 6. However, these are resins using alkylene glycol or alicyclic alcohol having a small number of carbon atoms with respect to the carboxylic acid component of terephthalic acid. Although there is a description of crystalline polyester resin in it, it is a partially crystalline polyester, and the viscosity change with respect to the temperature of the toner (resin) is not steep, and there is no problem in blocking property and image storability after fixing. In hot roll fixing, it was not possible to realize low temperature fixing more than conventional.

An example in which a crystalline polyester resin is used for toner is described in Patent Document 7 and the like. A method has been proposed in which an amorphous polyester having a glass transition temperature of 40 ° C. or higher and a crystalline polyester having a melting point of 130 ° C. to 200 ° C. are mixed and used. However, although this method has excellent pulverization properties and blocking resistance, since the melting point of the crystalline polyester resin is high, the low-temperature fixability cannot be achieved as compared with the conventional method.
In addition, there is an example in which a crystalline resin having a melting point of 110 ° C. or lower is used, and a non-crystalline resin is mixed and used as a toner. (Patent Document 8 etc.)
However, when an amorphous resin is mixed with a crystalline resin, the melting point of the toner is lowered, which causes practical problems such as toner blocking and deterioration of image storage stability. In addition, when the amount of the amorphous resin component is large, the characteristics of the amorphous resin component are largely reflected, so that it is difficult to lower the fixing temperature than before. Therefore, practical use is difficult unless a crystalline resin is used alone as a toner resin, or a very small amount is added even when an amorphous resin is mixed. Therefore, it has been required to use a crystalline polyester resin that is not partially crystalline.

Japanese Patent Publication No. 56-13943 Japanese Examined Patent Publication No.62-39428 Japanese Patent Publication No. 63-25335 Japanese Patent Laid-Open No. 4-120554 JP-A-4-239021 JP-A-5-165252 Japanese Examined Patent Publication No.62-39428 Japanese Patent Publication No. 4-30014

On the other hand, in order to realize low-temperature fixability, we have studied a toner using a crystalline resin. However, since the toner base material using a crystalline resin has a small charge amount, it has been proposed to use an amorphous resin having an appropriate charge as the shell. However, as the shell film thickness is increased in order to obtain the charge amount, the low-temperature fixability cannot be realized, and the characteristics of the crystalline resin are impaired.
In addition, when forming the core-shell structure, the volume shrinkage ratio of the core and the shell with respect to the temperature is different by slow cooling, a uniform joint interface cannot be obtained, sufficient interface strength cannot be obtained, and fine powder due to peeling of the shell layer However, due to adhesion to the carrier surface, the charging deterioration of the developer is accelerated, or the generated fine powder easily migrates to the developing roll, photoconductor, carrier, etc., so the developing roll, photoconductor and carrier are easily contaminated. There was concern that it would lead to a decline in reliability.

In view of the above problems, the present invention has been made for the purpose of solving the problems.
That is, the present invention improves the interfacial strength of the joint interface between the core and the shell while lowering the fixing temperature to prevent the shell layer from peeling off, thereby preventing the generation of fine powder and improving the reliability of the image. It is an object of the present invention to provide a method for producing an electrophotographic toner that can be produced, an electrophotographic toner obtained by the method, a developer containing the toner, and an image forming method using the developer.

Means for solving the above problems are as follows.
<1> In an electrophotographic toner having a core-shell structure in which the surface of a toner base particle composed of at least a binder resin, a colorant, and a release agent is covered with an amorphous resin, an aggregating agent is added to the binder resin particles. An aggregating step for aggregating the colorant particles; an attaching step for adhering the amorphous resin particles to the particle surface; a coalescing step for coalescing the particles at a temperature equal to or higher than the melting point of the binder resin; and at least 10 ° C. / And a cooling step in which the temperature is lowered to a temperature equal to or lower than the crystallization temperature of the binder resin at a rate of at least minutes.
<2> The method for producing an electrophotographic toner according to <1>, wherein the crystalline resin that is a binder resin of the core is a crystalline polyester resin.
<3> The method for producing an electrophotographic toner according to <2>, wherein the crystalline polyester resin is an aliphatic crystalline polyester resin.
<4> The toner for electrophotography according to <2>, wherein the crystalline polyester resin contains a dicarboxylic acid containing a sulfonic acid group or a diol as a copolymerization component.
<5> An electrophotographic toner obtained by the production method according to any one of <1> to <4>.
<6> A developer comprising the toner according to <5> and a carrier.
<7> A latent image forming step for forming an electrostatic latent image on the surface of the latent image holding member, and a toner image is formed by developing the electrostatic latent image formed on the surface of the latent image holding member with a developer containing toner. An image forming process including: a developing step for transferring; a transfer step for transferring the toner image formed on the surface of the latent image holding member to a transferred member; and a fixing step for fixing the toner image transferred on the surface of the transferred member. In the method, the developer is the developer described in <6>.

In the present invention, the use of a crystalline polyester resin having a melting point and a sharp melt property as a main component of the binder resin enables fixing at a lower temperature than conventional. Further, by coating the toner base particles with a hard amorphous resin, it is possible to provide an electrophotographic toner imparted with appropriate electrophotographic properties such as development, transfer and cleaning properties. Furthermore, in order to satisfy the core-shell structure, by rapid cooling, crystal growth of the crystalline polyester as the core layer is suppressed, and volume shrinkage of the core before and after cooling is suppressed. Since the shell layer is amorphous, the volume shrinkage before and after the rapid cooling is smaller than that of the crystalline layer. Therefore, a bonding interface is generated between the core layer and the shell layer, whose volume shrinkage is suppressed by the rapid cooling. As a result of the bonded interface, the strength of the interface between the core layer and the shell layer is increased, and the adhesion strength between the core and shell is increased, so that the generation of fine powder can be suppressed by eliminating the peeling off of the shell layer. Further, it is possible to provide an electrophotographic toner having a long development life.
In addition, since an electrophotographic toner can be obtained with the particle diameter and shape kept at the time of rapid cooling, an electrophotographic toner that can be easily cleaned can be provided. The energy in the fixing process can be greatly reduced, and the warm-up time can be shortened.

  According to the present invention, the strength of the joint interface of the core / shell structure is high and the shell does not peel off while maintaining the low temperature fixing, so that the development life is long and the image can be formed with high reliability.

<Toner for electrophotography>
The toner for electrophotography (hereinafter referred to as “toner”) used in the present invention contains at least a binder resin and a colorant, and contains a crystalline resin having a melting point of 50 to 100 ° C. as a main component. As the crystalline resin, a crystalline polyester resin is preferable, and an aliphatic crystalline polyester resin having an appropriate melting point is more preferable. Hereinafter, a crystalline polyester resin will be described as an example.

  The crystalline polyester resin is synthesized from an acid (dicarboxylic acid) component and an alcohol (diol) component. In the present invention, the “acid-derived component” refers to an acid component before synthesis of the polyester resin. The “alcohol-derived constituent component” refers to a constituent portion that was an alcohol component before the synthesis of the polyester resin.

  When the polyester resin is not crystalline, that is, amorphous, it is impossible to maintain toner blocking resistance and image storage stability while ensuring good low-temperature fixability. Therefore, in the present invention, the “crystalline polyester resin” refers to a resin having a clear endothermic peak rather than a stepwise endothermic amount change in differential scanning calorimetry (DSC). In the case of a polymer obtained by copolymerizing another component with the crystalline polyester main chain, when the other component is 50% by weight or less, this copolymer is also called crystalline polyester.

-Acid-derived components-
The acid-derived constituent component is preferably an aliphatic dicarboxylic acid, and particularly preferably a linear carboxylic acid. For example, succinic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid Acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc., or lower alkyl esters thereof And acid anhydrides, but are not limited thereto.

  As the acid-derived constituent component, in addition to the above-mentioned aliphatic dicarboxylic acid-derived constituent component, constituent components such as a dicarboxylic acid-derived constituent component having a double bond and a dicarboxylic acid-derived constituent component having a sulfonic acid group are included. Is preferred.

  The component derived from a dicarboxylic acid having a double bond is derived from a lower alkyl ester or acid anhydride of a dicarboxylic acid having a double bond, in addition to a component derived from a dicarboxylic acid having a double bond. Components are also included. The dicarboxylic acid-derived constituent component having a sulfonic acid group is derived from a lower alkyl ester or acid anhydride of a dicarboxylic acid having a sulfonic acid group, in addition to a constituent component derived from a dicarboxylic acid having a sulfonic acid group. Components are also included.

  The dicarboxylic acid having a double bond can be suitably used to prevent hot offset at the time of fixing since the entire resin can be crosslinked using the double bond. Examples of such dicarboxylic acids include, but are not limited to, fumaric acid, maleic acid, 3-hexenedioic acid, and 3-octenedioic acid. Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. Among these, fumaric acid, maleic acid and the like are preferable in terms of cost.

  The dicarboxylic acid having a sulfonic acid group is effective in that it can favorably disperse a coloring material such as a pigment. Further, when emulsifying or suspending the entire resin in water to produce toner mother particles into fine particles, if there are sulfonic acid groups, emulsification or suspension is possible without using a surfactant, as will be described later. . Examples of such a dicarboxylic acid having a sulfone group include, but are not limited to, 2-sulfoterephthalic acid sodium salt, 5-sulfoisophthalic acid sodium salt, and sulfosuccinic acid sodium salt. Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. Among these, 5-sulfoisophthalic acid sodium salt is preferable in terms of cost.

  Content of acid-derived components other than aliphatic dicarboxylic acid-derived components (dicarboxylic acid-derived components having double bonds and / or dicarboxylic acid-derived components having sulfonic acid groups) in the acid-derived components 1 to 20 mol% is preferable, and 2 to 10 mol% is more preferable.

  When the content is less than 1 constituent mol%, pigment dispersion may not be good, the emulsified particle diameter may be large, and adjustment of the toner diameter by aggregation may be difficult. On the other hand, if it exceeds 20 component mol%, the crystallinity of the polyester resin is lowered, the melting point is lowered, the image storage stability is deteriorated, or the emulsion particle size is too small to dissolve in water, and no latex is produced. Sometimes.

  In the present invention, “constituent mol%” refers to a percentage when each constituent component (acid-derived constituent component, alcohol-derived constituent component) in the polyester resin is defined as one unit (mol).

-Alcohol-derived components-
The alcohol component is preferably an aliphatic dicarboxylic acid, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptane. Diol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-dodecanediol, 1,12-undecanediol, 1,13-tridecanediol, 1,14-tetradecane Examples include, but are not limited to, diol, 1,18-octadecanediol, 1,20-eicosanediol, and the like.

  When the alcohol-derived constituent component is an aliphatic diol-derived constituent component, the content of the aliphatic diol-derived constituent component is 80 constituent mol% or more, and other components are included as necessary. Furthermore, when the alcohol-derived constituent component is an aliphatic diol-derived constituent component, the content of the aliphatic diol-derived constituent component is preferably 90 constituent mol% or more.

  When the content of the aliphatic diol-derived constituent component is less than 80 constituent mol%, the crystallinity of the polyester resin is lowered and the melting point is lowered, so that toner blocking resistance, image storage stability, and low-temperature fixability are deteriorated. End up.

  Other components included as necessary include diol-derived components having double bonds and diol-derived components having sulfonic acid groups. Examples of the diol having a double bond include 2-butene-1,4-diol, 3-butene-1,6-diol, 4-butene-1,8-diol, and the like. Examples of the diol having a sulfonic acid group include 1,4-dihydroxy-2-sulfonic acid benzene sodium salt, 1,3-dihydroxymethyl-5-sulfonic acid benzene sodium salt, and 2-sulfo-1,4-butanediol sodium. Examples include salts.

  When adding an alcohol-derived component other than these linear aliphatic diol-derived components, that is, when adding a diol-derived component having a double bond and / or a diol-derived component having a sulfonic acid group, The content of the diol-derived constituent component having a double bond and / or the diol-derived constituent component having a sulfonic acid group in the alcohol-derived constituent component is preferably 1-20 constituent mol%, and more preferably 2-10 constituent mol%.

  When the content of the alcohol-derived constituent component other than the aliphatic diol-derived constituent component is less than 1 constituent mol% with respect to the total alcohol-derived constituent component, the pigment dispersion is not good or the emulsion particle size is increased. In some cases, it is difficult to adjust the toner diameter by aggregation. On the other hand, if it exceeds 20 component mol%, the crystallinity of the polyester resin is lowered, the melting point is lowered, the image storage stability is deteriorated, or the emulsion particle size is too small to dissolve in water, and no latex is produced. Sometimes.

  The method for producing the polyester resin is not particularly limited, and can be produced by a general polyester polymerization method in which an acid component and an alcohol component are reacted. For example, direct polycondensation, transesterification method, etc. Produced separately for different types. The molar ratio (acid component / alcohol component) when the acid component reacts with the alcohol component varies depending on the reaction conditions and the like, and cannot be generally stated, but is usually about 1/1.

  The production of the polyester resin can be carried out at a polymerization temperature of 180 to 230 ° C., and the reaction system is reacted under reduced pressure as necessary to remove water and alcohol generated during condensation.

  When the monomer is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added as a solubilizer and dissolved. In the polycondensation reaction, the dissolution auxiliary solvent is distilled off. If there is a monomer with poor compatibility in the copolymerization reaction, the monomer with poor compatibility and the monomer and the acid or alcohol to be polycondensed may be condensed in advance before polycondensation with the main component. .

  Catalysts that can be used in the production of the polyester resin include alkali metal compounds such as sodium and lithium, alkaline earth metal compounds such as magnesium and calcium, and metal compounds such as zinc, manganese, antimony, titanium, tin, zirconium, and germanium. , Phosphorous acid compounds, phosphoric acid compounds, amine compounds, etc., specifically, sodium acetate, sodium carbonate, lithium acetate, lithium carbonate, calcium acetate, calcium stearate, magnesium acetate, zinc acetate, stearic acid Zinc, zinc naphthenate, zinc chloride, manganese acetate, manganese naphthenate, titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, antimony trioxide, triphenylantimony, trib Ruantimony, tin formate, tin oxalate, tetraphenyltin, dibutyltin dichloride, dibutyltin oxide, diphenyltin oxide, zirconium tetrabutoxide, zirconium naphthenate, zirconyl carbonate, zirconyl acetate, zirconyl stearate, zirconyl octylate, germanium oxide, triphenyl Examples of the compound include phosphite, tris (2,4-di-t-butylphenyl) phosphite, ethyltriphenylphosphonium bromide, triethylamine, and triphenylamine.

  The melting point of the binder resin of the present invention is 50 to 100 ° C., preferably 60 to 95 ° C. When the melting point is lower than 50 ° C., the storage stability of the toner and the storage stability of the toner image after fixing become a problem. On the other hand, when the temperature is higher than 100 ° C., sufficient low-temperature fixing cannot be obtained as compared with the conventional toner.

  In the present invention, the melting point of the crystalline resin is measured using a differential scanning calorimeter (DSC) using JIS K- when the temperature is measured from room temperature to 150 ° C. at a rate of temperature increase of 10 ° C. per minute. The melting peak temperature of the input compensation differential scanning calorimetry shown in 7121 can be obtained. The crystalline resin may show a plurality of melting peaks, but in the present invention, the maximum peak is regarded as the melting point.

  If the weight average molecular weight of the crystalline resin is too small, the fixing strength may be insufficient, and crushing may occur while stirring the developing device. If the weight average molecular weight is too large, the fixing temperature may increase. Or less, preferably 15000-40000, more preferably 20000-30000.

  The colorant of the present invention may be a dye or a pigment, but a pigment is preferred from the viewpoint of light resistance and water resistance. Preferred pigments include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, Quinacridone, benzidine yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 185, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. Known pigments such as CI Pigment Blue 15: 3 can be used. Magnetic powder can also be used as a colorant. As the magnetic powder, known magnetic materials such as ferromagnetic metals such as cobalt, iron and nickel, alloys of metals such as cobalt, iron, nickel, aluminum, lead, magnesium, zinc and manganese, and oxides can be used.

  These can be used alone or in combination of two or more. The content of these colorants is preferably 0.1 to 40 parts by weight, and more preferably 1 to 30 parts by weight.

  In addition, by appropriately selecting the type of the colorant, each color toner such as yellow toner, magenta toner, cyan toner, and black toner can be obtained.

  In the present invention, an amorphous resin (also referred to as an amorphous polymer) as a shell material is a resin having no endothermic peak due to crystal melting in thermal analysis measurement using differential scanning calorimetry (DSC), A solid at room temperature, which is thermoplasticized at a temperature above the glass transition temperature. (Hereinafter, the resin used for the shell material may be called the coating resin, and the core resin may be called the core resin.) Specifically, styrenes such as styrene, parachlorostyrene, α-methylstyrene, methyl acrylate, acrylic acid Α-methylene fatty acid monocarboxylic acids such as ethyl, n-propyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, methacrylic acid, n-propyl lauryl methacrylate 2-ethylhexyl, dimethylaminoethyl methacrylate Nitrogen-containing acrylics such as acrylonitrile, vinyl nitriles such as acrylonitrile and methacrylonitrile, vinyl pyridines such as 2-vinyl pyridine and 4-vinyl pyridine, vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether, vinyl methyl ketone and vinyl Homopolymers such as vinyl ketones such as ethyl ketone and vinyl isopropenyl ketone, olefins such as ethylene, propylene, butadiene and isoprene, vinyl-based fluorine-containing monomers such as vinylidene fluoride, tetrafluoroethylene and hexafluoroethylene, or 2 Copolymers composed of more than one monomer, silicones such as methyl silicone and methyl phenyl silicone, polyesters containing bisphenol, glycol, etc., epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, polycarbonate resins Examples thereof include non-vinyl condensation resins and graft polymers of these non-vinyl condensation resins and vinyl monomers. These resins may be used alone or in combination of two or more. The amount of the coating resin is about 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight with respect to the core particles.

  Among these resins, a polyester resin is particularly preferable in order to promote compatibilization of the core and the shell from the viewpoint of the bondability between the core and the shell.

  The polyester resin can be usually synthesized by using a conventionally known method such as a transesterification method or a polycondensation method by selecting and combining suitable ones from a dicarboxylic acid component and a diol component.

  Examples of the dicarboxylic acid component of the amorphous polyester resin include terephthalic acid, isophthalic acid, cyclohexane dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, naphthalene dicarboxylic acid such as naphthalene-2,7-dicarboxylic acid, and biphenyl dicarboxylic acid. Etc. In addition, dibasic acids such as succinic acid, glutaric acid, adipic acid, speric acid, azelaic acid, sebacic acid, phthalic acid, malonic acid, and mesaconic acid, and anhydrides and lower alkyl esters thereof; maleic acid, fumaric acid Examples thereof include aliphatic unsaturated dicarboxylic acids such as acid, itaconic acid and citraconic acid. In addition, trivalent or higher carboxylic acids such as 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid and the like, and anhydrides and lower alkyl esters thereof. Can be used in combination. In addition, it is also possible to use monovalent acids, such as an acetic acid and a benzoic acid, for the objectives, such as preparation of an acid value and a hydroxyl value, as needed.

  Examples of the diol component include ethylene glycol, propylene glycol, neopentyl glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, trimethylene oxide adduct of bisphenol A, and the like. Further, bisphenol A, hydrogenated bisphenol A, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentane Examples include diol, 1,6-hexanediol, neopentyl glycol, and the like. Moreover, if it is trace amount, trivalent or more alcohols, such as glycerol, a trimethylol ethane, a trimethylol propane, a pentaerythritol, can be used together. These may be used individually by 1 type and may use 2 or more types together. Monovalent alcohols such as cyclohexanol and benzyl alcohol can also be used.

  As an electrophotographic toner having a core-shell structure, one of the purposes of having a shell is to impart charging characteristics. For the above purpose, JP-A-57-202547, JP-A-63-27853, and JP-A-63-27854 disclose that a polymer containing a charge control agent is spray-dried on a toner, or heated or heated. A method for obtaining toner by coating with pressure is described.

However, the spray drying method has a drawback in that a plurality of toner bases are wrapped in a coating layer, and the toner particle size becomes large. Thereafter, even if the sieving operation is performed, the yield of toner having a predetermined particle diameter is low. Furthermore, since a large amount of organic solvent is used, there is a problem in safety and health. In addition, the method of coating on the toner base by heat fusion also has a drawback that the toner particle size is increased by causing adhesion and aggregation of the toners. Furthermore, since the bonding interface between the core and shell is not sufficient, the shell peels off due to mechanical force, and fine powder is generated, and easily transferred to the developing roll, photoconductor, carrier, etc. This is not preferable because contamination easily occurs and leads to a decrease in reliability.
Examples include various known additives such as inorganic fine particles, charge control agents, and release agents.

  If necessary, inorganic fine particles may be added to the toner of the present invention. As the inorganic fine particles, silica fine particles, titanium oxide fine particles, alumina fine particles, cerium oxide fine particles, or known inorganic fine particles such as those obtained by hydrophobizing the surface thereof can be used alone or in combination of two or more kinds. Silica fine particles having a refractive index smaller than that of the binder resin are preferable from the viewpoint that transparency such as color developability and OHP permeability is not impaired. The silica fine particles may be subjected to various surface treatments, and for example, those subjected to surface treatment with a silane coupling agent, a titanium coupling agent, silicone oil or the like are preferable.

  By adding these inorganic fine particles, the viscoelasticity of the toner can be adjusted, and the glossiness of the image and the penetration into the paper can be adjusted. The inorganic fine particles are preferably contained in an amount of 0.5 to 20% by weight, more preferably 1 to 15% by weight, based on the raw material.

  If necessary, a charge control agent may be added to the toner of the present invention. As the charge control agent, chromium-based azo dyes, iron-based azo dyes, aluminum azo dyes, salicylic acid metal complexes, and the like can be used.

  The toner used in the present invention preferably contains a release agent. By including a release agent, the releasability in the fixing process is improved. In the contact heating type fixing method, the release oil applied to the fixing roll can be reduced or eliminated. Deterioration of roll life and oil streaks can be avoided, and the cost can be reduced.

  Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide Plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax・ Petroleum-based wax.

  The melting point of the release agent is preferably 50 to 120 ° C., and more preferably below the melting point of the binder resin. If the melting point of the release agent is less than 50 ° C., the change temperature of the release agent is too low, and the blocking resistance is inferior, or the developability deteriorates when the temperature in the copying machine increases. On the other hand, when it exceeds 120 ° C., the viscosity change temperature of the release agent is too high, and the low-temperature fixability of the crystalline resin is impaired.

  Moreover, in this invention, these mold release agents may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the release agent is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight with respect to 100 parts by weight of the toner raw material. If it is less than 1 part by weight, there is no effect of adding a release agent, and if it is 20 parts by weight or more, deformation of the toner may occur due to stress inside the toner particles generated by volume change of the release agent in the cooling step, Since the release agent tends to appear on the toner surface, the chargeability is adversely affected, and the toner is easily destroyed inside the developing machine, so that the release agent or toner resin becomes spent on the carrier, and charging In addition, for example, when a color toner is used, exudation to the image surface at the time of fixing tends to be insufficient, and the release agent tends to stay in the image. Therefore, transparency is deteriorated, which is not preferable.

  The volume average particle diameter of the electrophotographic toner of the present invention is 3.0 to 7.5 μm, more preferably 3.5 to 6.5 μm, and still more preferably 3.8 to 6.2 μm. When the volume average particle diameter is smaller than 3.0 μm, the chargeability is not sufficient, and the spread of the charge distribution due to the decrease in fluidity tends to cause fogging on the background or toner spillage from the developing device. When the volume average particle diameter is larger than 7.5 μm, the resolution is lowered, and sufficient image quality cannot be obtained.

  The volume average particle diameter can be measured, for example, by measuring with a 50 μm aperture diameter using a Coulter counter [TA-II] type (manufactured by Beckman-Coulter). At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds.

<Preferable Physical Properties of Electrophotographic Toner of the Present Invention>
The toner for electrophotography of the present invention is desired to have sufficient hardness at room temperature. Specifically, when the dynamic viscoelasticity is an angular frequency of 1 rad / sec and 30 ° C., the storage elastic modulus GL (30) is 1 × 10 6 Pa or more and the loss elastic modulus GN (30) is 1 × 10 6 Pa or more. It is desirable to be. Details of the storage elastic modulus GL and the loss elastic modulus GN are defined in JIS K 6900.

When the storage elastic modulus GL (30) is less than 1 × 10 ⁶ Pa or the loss elastic modulus GN (30) is less than 1 × 10 ⁶ Pa at an angular frequency of 1 rad / sec and 30 ° C., it is mixed with the carrier in the developing machine. In such a case, the toner particles may be deformed by the pressure or shearing force received from the carrier, and stable charge development characteristics may not be maintained. Further, when the toner on the latent image holding member (photosensitive member) is cleaned, it may be deformed by a shearing force received from the cleaning blade, resulting in poor cleaning.

  When the storage elastic modulus GL (30) and the loss elastic modulus GN (30) are in the above ranges at the angular frequency of 1 rad / sec and 30 ° C., the characteristics during fixing are stable even when used in a high-speed electrophotographic apparatus. It is preferable.

 Further, in the electrophotographic toner of the present invention, a temperature interval in which the change in the storage elastic modulus GL and the loss elastic modulus GN due to a temperature change becomes two digits or more in a temperature range of 10 ° C. Preferably, it has a temperature interval in which the values of GL and GN change to values of 1/100 or less when raised. If the storage elastic modulus GL and the loss elastic modulus GN do not have the temperature section, the fixing temperature becomes high, and as a result, it may be insufficient to reduce the energy consumption of the fixing process.

Further, when the common logarithm of the storage elastic modulus is plotted against the temperature, the electrophotographic toner of the present invention has a storage elastic modulus at a temperature 20 ° C. higher than the melting point Tm (Tm + 20 ° C.) at GL (Tm + 20) and the melting point Tm. When the storage elastic modulus at a temperature higher by 50 ° C. (Tm + 50 ° C.) is GL (Tm + 50), the following formula (1) is satisfied,
log GL (Tm + 20) −log GL (Tm + 50) | ≦ 1.5 (1)
When the common logarithm of the loss elastic modulus is plotted against the temperature, the loss elastic modulus at a temperature 20 ° C. higher than the melting point Tm (Tm + 20 ° C.) is GN (Tm + 20), and the temperature 50 ° C. higher than the melting point Tm (Tm + 50 ° C.). When the loss elastic modulus is GN (Tm + 50), the following formula (2)
logGN (Tm + 20) −logGN (Tm + 50) | ≦ 1.5 (2)
It is preferable to satisfy the above condition in order to reduce non-uniformity of image gloss caused by temperature distribution or the like depending on the image part.

  This index indicates that the viscosity of the electrophotographic toner of the present invention has a moderate dependence on temperature after the melting point, and means that the temperature dependence of viscoelasticity becomes lower.

  FIG. 1 is a graph showing preferable characteristics of the electrophotographic toner of the present invention. In FIG. 1, the vertical axis represents the common logarithm log GL of the storage elastic modulus or the common logarithm log GN of the loss elastic modulus, and the horizontal axis represents the temperature. The electrophotographic toner of the present invention having such characteristics exhibits a sudden drop in elastic modulus at the melting point in the temperature range of 50 to 100 ° C., and the elastic modulus is stable within a predetermined range. It is possible to prevent unevenness of image gloss resulting from the temperature distribution due to the image part at the time of fixing, and excessive permeation to a transfer medium such as paper even at high temperatures.

  Since the electrophotographic toner of the present invention has the above-described configuration, it is excellent in toner blocking resistance, image storage stability, and low-temperature fixability.

In the toner of the present invention, 1) the content of the crystalline polyester is in the range of 20 to 90% by weight, and 2) the volume electric resistance value is 2.0 × 10 ^{13 to} 1.0 × 10 ¹⁵ Ω · cm. 3) The BET non-surface area of the toner is preferably 2.0 or less. When the content of the crystalline polyester resin is in the range of 20 to 90% by weight, good low-temperature fixability can be obtained. More preferably, the content of the crystalline polyester is in the range of 30 to 85% by weight. When the toner resistance value is 2.0 × 10 ¹³ Ω · cm or more, the developing property is good without insufficient charge amount of the toner. The toner resistance value is more preferably 3.0 × 10 ¹³ Ω · cm or more, and the upper limit of the resistance value is about 1.0 × 10 ¹⁵ Ω · cm.
The resistance value is measured by compression-molding 4 g of toner powder, seasoning a disk-shaped product under high temperature and high humidity (28 ° C., 85% RH) for 10 hours, and measuring the volume resistance. The toner resistance value can be adjusted by changing the crystalline resin content, the amount of polar groups in the crystalline resin composition, and the like.

In the toner of the present invention, when the BET specific surface area is 2.0 m ² / g or less, the toner surface becomes smooth, and good fluidity and transferability can be exhibited without the toner external additives being buried in the toner surface. . A BET surface area means the value measured using Shimadzu powder specific surface area measuring device SS-100 type.

When the dynamic complex viscosity of the toner at the melting point of the crystalline resin + 50 ° C. is 50 Pa.s or more, a wide fixing latitude can be obtained.
The dynamic complex viscosity (η ^* ) is measured using a rheometer at a frequency of 1 rad / sec. The temperature is raised from the melting point by heating at a heating rate of 1 ° C./min. Measure the dynamic complex modulus. The measurement distortion was 20% or less, and 8mmφ and 25mmφ parallel plates were used depending on the measurement torque.
In order to prevent hot offset, the dynamic complex viscosity of the toner at the melting point of the crystalline resin + 50 ° C. is preferably 50 Pa.s or more, more preferably 100 Pa.s or more. The upper limit of the dynamic complex viscosity is about 1 × 10 ⁵ Pa.s in consideration of cold offset.
In order to fix by utilizing the melting point of the crystalline resin for low-temperature fixability, the dynamic complex viscosity at the melting point of the crystalline resin + 10 ° C. is preferably 1 × 10 ⁵ Pa.s or less. More preferably, it is 5 × 10 ⁴ Pa.s or less.
The dynamic complex viscosity is adjusted by adjusting the ratio of the binder resin in the core and shell parts, the molecular weight of the binder resin, particularly the crystalline resin contained in the core part, and the aggregation used in the agglomeration and coalescence process when making the toner. It is possible by changing the presence or absence of the agent or its type.

In the toner of the present invention, the amount of sodium in the toner measured by a fluorescent X-ray analyzer is 0.5 atomic% or less with respect to the total of carbon and oxygen, and an X-ray photoelectron spectrometer (XPS) The measured amount of sodium in the toner particle surface layer is preferably 0.7 atomic% or less with respect to the total of carbon and oxygen.

The amount of sodium in the toner particles was determined by quantitative analysis using a fluorescent X-ray analyzer and defined as follows. Note that XRF-1500 manufactured by Shimadzu Corporation was used for the measurement with the fluorescent X-ray analyzer. The amount of sodium on the toner particle surface was determined by surface analysis using an X-ray photoelectron spectrometer (XPS), and was defined as follows in the same manner as the amount of sodium in the toner particles. Note that JPS-9000MX manufactured by JEOL Ltd. was used for XPS measurement.

Since the toner of the present invention has a core-shell structure having a very thin shell with respect to the toner particle diameter of 0.01 to 0.3 μm, the result of quantitative analysis by the fluorescent X-ray analyzer is the amount of sodium in the core layer. The results of quantitative analysis of the toner surface by XPS represent the amount of sodium in the shell layer.
(Mass ratio% of sodium metal) = (sodium detection amount) / [(C detection amount) + (O detection amount)] × 100%

The surface of the toner of the present invention is preferably smooth, and the surface property index value obtained by correcting the measured value of the surface area by the nitrogen adsorption method using the BET equation with the particle size considering the particle size distribution is 3.0 or less. It is preferable that The surface property index value is represented by the following formula. The specific surface area was measured using a flow soap 2300 manufactured by Shimadzu Corporation using the BET equation and the nitrogen adsorption one-point method.
(Surface property index value) = 6Σ (n × R ² ) / [σ × Σ (n × R ³ )]
(Where n = number of toner particles in the channel at the Coulter counter, R = channel particle diameter (center value) at the Coulter counter, σ = toner density)
Furthermore, it is preferable that the toner surface of the present invention has no holes. The presence or absence of holes on the toner surface was observed using a scanning electron microscope (SEM). In addition, SEM observation was performed using Hitachi, Ltd. S-4700.

The toner of the present invention preferably has an indeterminate shape in order to provide excellent cleaning properties, and the shape factor SF1 is preferably in the range of 125 to 140. Specifically, it is a percentage display value of a value obtained by dividing the area of a circle whose diameter is the maximum diameter (L) of the particle when each toner particle is projected in a plane by the projected area (A) of the particle, and It is defined by an expression. A Luzex image analyzer was used to measure the shape factor.
(SF1) = (π / 4) × (L ² / A) × 100 (%) (where L = maximum length of toner projection area, A = toner projection area)

<Method for producing electrophotographic toner>
The method for producing an electrophotographic toner of the present invention is a wet granulation method in which at least a binder resin particle dispersion and a colorant particle dispersion are mixed and a flocculant is added to grow particles. As specific examples of this wet granulation method, the following emulsion aggregation method is preferably exemplified. Hereinafter, the emulsion aggregation method will be described as an example. A crystalline polyester resin will be described as an example of the crystalline resin.

  The emulsification aggregation method includes an emulsification step of emulsifying the crystalline polyester resin already described in the section of “Binder resin” in the “electrophotographic toner” of the present invention to form emulsified particles (droplets); An aggregation step of forming an aggregate of particles (droplets), and a coalescence step of fusing the aggregate at a temperature equal to or higher than the melting point of the crystalline polyester resin to thermally coalesce. Alternatively, instead of the aggregation step and the coalescence step, a so-called association step may be performed in which aggregation and coalescence are simultaneously performed by aggregating at a temperature equal to or higher than the melting point of the crystalline polyester resin. Amorphous resin particles are added at an appropriate timing during the coalescence process, after the coalescence process, during the association process, or after the association process, and the amorphous resin is attached to the crystalline resin that is the toner base particle. And having a coating step in which an electrophotographic toner having a core-shell structure with a crystalline resin as a toner base particle as a core and an amorphous resin as a coating resin as a shell can be obtained. Not only the characteristics of one resin, but also the effect of imparting characteristics expressed by the coating resin.

  In the emulsification step, the emulsified particles (droplets) of the polyester resin are mixed into a solution obtained by mixing an aqueous medium and a sulfonated polyester resin and, if necessary, a mixed liquid (polymer liquid). It is formed by applying a shearing force.

  In that case, the viscosity of a polymer liquid can be lowered | hung by heating to the temperature beyond melting | fusing point of crystalline polyester resin, and an emulsified particle can be formed. Moreover, a dispersing agent can also be used for stabilization of emulsified particles and thickening of the aqueous medium. Hereinafter, such a dispersion of emulsified particles may be referred to as a “resin particle dispersion”.

  Examples of the dispersant include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, and sodium polyacrylate; sodium dodecylbenzenesulfonate, sodium octadecyl sulfate, sodium oleate, sodium laurate, and potassium stearate. Anionic surfactants such as; cationic surfactants such as laurylamine acetate and lauryltrimethylammonium chloride; zwitterionic surfactants such as lauryldimethylamine oxide; polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, Surfactants such as nonionic surfactants such as polyoxyethylene alkylamine; tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate Um, and inorganic compounds such as barium carbonate.

  As the usage-amount of the said dispersing agent, 0.01-20 weight part is preferable with respect to 100 weight part of said polyester resins (binder resin).

  In the emulsification step, the polyester resin is copolymerized with a dicarboxylic acid having a sulfonic acid group (that is, a suitable amount of a dicarboxylic acid-derived component having a sulfonic acid group is included in the acid-derived component). ) And dispersion stabilizers such as surfactants can be reduced, or emulsified particles can be formed without using them.

  Examples of the emulsifier used when forming the emulsified particles include a homogenizer, a homomixer, a pressure kneader, an extruder, and a media disperser. The size of the emulsified particles (droplets) of the polyester resin is preferably 0.005 to 1.0 [mu] m, and more preferably 0.01 to 0.4 [mu] m, in terms of the average particle size (volume average particle size). If it is 0.005 μm or less, it is almost dissolved in water, making it difficult to produce particles. If it is 1 μm or more, it is difficult to obtain particles having a desired particle size of 3.0 to 7.5 μm.

  As a method for dispersing the colorant, an arbitrary method, for example, a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used.

  If necessary, an aqueous dispersion of these colorants can be prepared using a surfactant. Hereinafter, such a colorant dispersion may be referred to as a “colored particle dispersion”. As the surfactant and the dispersing agent used for dispersion, the same dispersing agents that can be used when dispersing the polyester resin can be used.

  In addition, a colorant can be mixed into the resin before forming the emulsified particles. As a method of mixing the colorant into the resin, melt dispersion using a disperser or the like can be mentioned.

  In the agglomeration step, the obtained emulsified particles are aggregated by heating at a temperature near the melting point of the polyester resin and a temperature below the melting point to form an aggregate.

  Formation of the aggregate of the emulsified particles is performed by acidifying the pH of the emulsion under stirring. As said pH, 2-6 are preferable and 2.5-5 are more preferable. At this time, it is also effective to use a flocculant.

  The flocculant used is a surfactant having a polarity opposite to that of the surfactant used for the dispersant, and inorganic metal salts such as sodium chloride, magnesium carbonate, magnesium chloride, magnesium nitrate, magnesium sulfate, calcium chloride, and aluminum sulfate. A divalent or higher valent metal complex can be suitably used.

  In the coating step, the surface of the agglomerated particles containing crystalline polyester (hereinafter also referred to as core agglomerated particles) formed through the agglomeration step under the same agitation as in the agglomeration step is amorphous. A resin is attached, and the attached amorphous resin is connected to each other on the surface of the core aggregated particle on the surface of one particle, whereby a coating layer can be formed on the surface of the core aggregated particle. This coating layer corresponds to the outermost surface of the toner of the present invention formed during any of the steps of coalescence of the core agglomerated particles, coalescence, association, after association, and cooling.

  The coating layer can be formed by additionally adding a dispersion containing amorphous polymer particles to the dispersion in which the core aggregated particles are formed in the aggregation step or the association step, and other components as necessary. May be added at the same time. According to the amorphous polymer to be used, the pH and the flocculant can be selected and adhered to the core aggregated particles in the same manner as in the aggregation step. In this coating step, it is also effective to lead the raw material fine particles that have not been taken into the aggregated particles at the pre-aggregation stage.

  In the coalescence step, under the same agitation as in the aggregation step, the pH of the suspension of the aggregate is set in the range of 3 to 10 to stop the progress of aggregation, and the crystalline polyester resin as the core By heating and stirring at a temperature higher than the melting point and higher than the glass transition temperature of the amorphous polymer as the shell, the cores that are aggregates are fused and united. In addition, the shell attached to the core is coated to form a core-shell structure. There is no problem if the heating temperature is not lower than the melting point of the crystalline polyester resin and not lower than the glass transition point of the amorphous resin. Further, the heating time may be performed so that the coalescence is sufficiently performed, and may be performed for about 0.2 to 10 hours.

  Thereafter, when the temperature is lowered to a temperature lower than the crystallization temperature of the crystalline polyester resin to solidify the particles, the shape and surface property of the particles and the bonding strength between the core aggregated particles and the coating resin layer change depending on the temperature lowering rate. For example, when the temperature is lowered at a high speed, spheroidization and the surface are easily smoothed, and a good bonding state between the core resin and the coating resin can be obtained, but conversely, when the temperature is lowered slowly, the particle shape is indefinite. And unevenness is likely to occur on the particle surface. Furthermore, the bonding state between the core resin and the coating resin is not good, and a gap is generated between the core shells, which may make it difficult to obtain sufficient adhesion strength. As a result, the shell layer is peeled off in the developing device, and the generated fine powder easily moves to the developing roll, the photoconductor, the carrier, etc. It leads to a decline in sex. Therefore, it is preferable that the temperature is lowered at a rate of at least 10 ° C./min, preferably at a rate of 15 ° C./min or more, more preferably 30 ° C./min or more and below the crystallization temperature of the crystalline polyester resin. The core-shell structure can be made satisfactory by lowering the temperature at a rate of 10 ° C./min or more to crystallize the binder resin.

  Further, in the association step in which the aggregation step and the coalescence step are performed simultaneously, particles are grown by adding a pH or a flocculant in the same manner as in the aggregation step while heating at a temperature equal to or higher than the melting point of the polyester resin. Then, as in the case of the coalescence process, the temperature is lowered to a temperature below the crystallization temperature of the crystalline polyester resin at a rate of at least 10 ° C./min, and particle growth is stopped simultaneously with crystallization. Moreover, you may adjust pH before and after temperature fall. Since the aggregation process and the coalescence process can be performed simultaneously by taking the association process in this way, it is preferable in terms of simplification of the process. Similarly to the coalescence step, the core-shell structure can be satisfied by lowering the temperature to the crystallization temperature or lower at a rate of 10 ° C./min or higher when stopped.

  The particles obtained by fusing can be converted into toner particles through a solid-liquid separation process such as filtration, and a washing process and a drying process as necessary. In this case, in order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to sufficiently wash in the washing step.

  In the drying process, any method such as a normal vibration type fluidized drying method, a spray drying method, a freeze drying method, an air flow drying method, a flash jet method, or the like can be adopted. It is desirable that the toner particles have a moisture content after drying of 1.5% or less, preferably 1.0% or less.

  In the coalescence step or the association step, a crosslinking reaction may be performed when the crystalline polyester resin is heated to a melting point or higher, or after the coalescence is completed. When the crosslinking reaction is performed, for example, an unsaturated sulfonated crystalline polyester resin obtained by copolymerizing a double bond component is used as the binder resin, and for example, t-butylperoxy-2-ethylhexa is added to this resin. A crosslinking reaction is introduced by causing a radical reaction using a polymerization initiator such as noate.

  The polymerization initiator may be mixed with the polymer in advance before the emulsification step, or may be incorporated into the aggregate in the aggregation step. Further, it may be introduced after the coalescence or association process, or after the coalescence or association process. In this case, a solution obtained by dissolving a polymerization initiator in an organic solvent may be added to a particle dispersion (resin particle dispersion or the like). These polymerization initiators may be added with known crosslinking agents, chain transfer agents, polymerization inhibitors and the like for the purpose of controlling the degree of polymerization.

  In the present invention, the core fused particles are washed with an acidic aqueous solution and ion-exchanged water to remove sodium, and then the amorphous resin particles are adhered and fused to form a core-shell structure. The agent is removed, and after washing with ion exchange water, sodium adhering during alkali washing is removed with an acidic aqueous solution, followed by washing with ion exchange water and drying to produce toner particles. The amount of sodium measured by the fluorescent X-ray analyzer of the toner particles is 0.5 atomic% or less based on the total amount of carbon and oxygen, and the amount of sodium on the toner particle surface measured by XPS is carbon and oxygen. By controlling the total amount to 0.7 atomic% or less, it is possible to produce toner particles that can be fixed at low temperature, have excellent cleaning characteristics, and have improved powder flowability, heat storage property and chargeability of the toner. Made possible.

  Moreover, in this invention, it is preferable to have the following core washing | cleaning process, adhering particle washing | cleaning process, and a drying process.

-Core cleaning process-
The fused core fused particles are washed using an acidic aqueous solution and a water washing solution. That is, the dispersion containing the core fusion particles is filtered, put into an acid cleaning aqueous solution, stirred, and then filtered. After repeating this step as desired, the same washing treatment is performed using ion-exchanged water. The washing treatment is preferably performed by adjusting the temperature of the acidic aqueous solution and ion-exchanged water to 35 to 40 ° C. If the temperature is lower than the above range, it is difficult to obtain a cleaning effect, and if it is too high, the core fusion particles are dissolved. Moreover, Na on the surface of the core fusion particle can be effectively removed by adjusting the pH of the acid washing to 3.0 to 6.0 and washing the core fusion particle. Furthermore, by washing with ion-exchanged water, impurities such as acidic aqueous solution components adhering to the surface of the core fusion particles can be removed, improving the adhesion of the amorphous polymer particles, and providing a smooth surface with no irregularities or holes. An encapsulated toner is obtained.

  Examples of the acid used for the treatment of the acidic solution include inorganic acids such as hydrochloric acid, nitric acid, and phosphoric acid, and various organic acids such as acetic acid, propionic acid, oxalic acid, phthalic acid, citric acid, and malic acid. I can do it.

-Adhesive particle cleaning process-
Next, an aqueous solution of an alkali metal hydroxide is added to the obtained toner slurry to raise the pH, followed by stirring and filtration. After repeating this step as desired, the same washing treatment is further performed using ion-exchanged water. For the above reasons, the washing treatment is preferably carried out by adjusting the temperature of the alkaline aqueous solution, acidic aqueous solution and ion-exchanged water to 35 to 40 ° C. In addition, it is desirable to perform the alkali cleaning by adjusting the pH to 8.0 to 10.0. If the pH is lower than the above range, the surfactant cannot be sufficiently removed, and if it is too high, the surface smoothness may be deteriorated and the transferability may be lowered. As the alkali metal hydroxide in the previous period, an aqueous sodium hydroxide solution is preferably used. Acid cleaning and water cleaning are performed in the same manner as the core fusion particle cleaning. By performing the above-described washing step, the surfactant and Na on the toner particle surface can be removed, and high chargeability can be imparted.

Examples of the alkali used for the treatment of the alkaline solution include inorganic bases such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, sodium carbonate and ammonia, and organic bases such as diethylamine, triethylamine and isopropylamine. It is done.

  In the drying process, an arbitrary method such as a normal vibration type fluidized drying method, a spray drying method, a freeze drying method, or a flash jet method can be employed. It is desirable that the toner particles have a moisture content after drying of 1.0% or less, preferably 0.5% or less.

  According to the electrophotographic toner manufacturing method of the present invention described above, the toner particle shape and surface smoothness, and the adhesion strength between the core resin and the coating resin can be controlled. The particle shape of the toner is preferably close to a spherical shape, and it is preferable that the toner has a coating layer with a smooth surface and a constant film thickness. By using a toner structure having a spherical and smooth and non-crystalline resin coating layer, non-electrostatic adhesion is reduced, transferability is improved, and external additives are less likely to be buried, resulting in transfer efficiency and Powder fluidity is also improved. Furthermore, the chargeability is improved and the charge maintenance is improved. Further, the storage stability in the developing device is also improved.

  In the toner of the present invention, an external additive such as a fluidizing agent or an auxiliary agent may be added to the surface of the toner particles. External additives include known fine particles such as silica fine particles, titanium fine particles, alumina fine particles, cerium oxide fine particles, carbon black and other inorganic fine particles, and polymer fine particles such as polycarbonate, polymethyl methacrylate and silicone resin. Of these, at least two kinds of external additives are used, and at least one of the external additives preferably has a volume average particle diameter of 30 nm to 200 nm, more preferably 30 nm to 180 nm. . As the toner particle size is reduced, non-electrostatic adhesion to the photoconductor increases, which causes transfer defects and image loss called hollow characters, and causes uneven transfer such as superimposed images. Therefore, it is preferable to add a large-sized external additive having a volume average particle size of 30 nm to 200 nm to improve transferability. If the volume average particle size is smaller than 30 nm, the initial toner fluidity is good, but the non-electrostatic adhesion between the toner and the photoreceptor cannot be sufficiently reduced, resulting in a decrease in transfer efficiency, and an image loss. Further, the uniformity of the image is deteriorated, and the fine particles are embedded in the toner surface due to the stress in the developing device over time, and the chargeability is changed, causing problems such as a decrease in copy density and fogging on the background portion. On the other hand, if the volume average particle size is larger than 200 nm, it is easy to be detached from the toner surface and the fluidity is deteriorated.

<Electrostatic image developer and carrier>
Examples of the developer of the present invention include a one-component developer composed only of toner and a two-component developer composed of toner and carrier, and a two-component developer excellent in charge maintenance and stability is preferable. The carrier is preferably a carrier coated with a resin, and more preferably a carrier coated with a nitrogen-containing resin.

  Examples of the nitrogen-containing resin include acrylic resins including dimethylaminoethyl methacrylate, dimethylacrylamide, acrylonitrile and the like, amino resins including urea, urethane, melamine, guanamine, aniline, amide resin, and urethane resin. These copolymer resins may also be used.

  Two or more of the nitrogen-containing resins may be used in combination as the carrier coating resin. Moreover, you may use combining the said nitrogen containing resin and resin which does not contain nitrogen. The nitrogen-containing resin may be used in the form of fine particles and dispersed in a resin not containing nitrogen. In particular, a urea resin, a urethane resin, a melamine resin, and an amide resin are preferable because they have high negative chargeability and high resin hardness, and can suppress a decrease in charge amount due to peeling of the coating resin.

In general, the carrier needs to have an appropriate electric resistance value, and specifically, an electric resistance value of about 10 ⁹ to 10 ¹⁴ Ωcm is required. For example, when the electrical resistance value is as low as 10 ⁶ Ωcm or less as in the case of an iron powder carrier, the carrier adheres to the image portion of the photoreceptor due to the charge injection from the sleeve, or the latent image charge escapes through the carrier and the latent image Problems such as image distortion and image loss occur. On the other hand, if the insulating resin is coated thickly, the electrical resistance value becomes too high and carrier charges are difficult to leak, resulting in an edged image. This causes a problem of an edge effect that the image density of the image becomes very thin. Therefore, it is preferable to disperse the conductive fine powder in the resin coating layer in order to adjust the resistance of the carrier.

  Specific examples of the conductive fine powder include metals such as gold, silver and copper, carbon black, semiconductive oxides such as titanium oxide and zinc oxide, titanium oxide, zinc oxide, barium sulfate and boric acid. Examples thereof include a surface of aluminum, potassium titanate powder or the like covered with tin oxide, carbon black, or metal. Among these, carbon black is preferable from the viewpoint of production stability, cost, and conductivity.

  Examples of the method for forming the resin coating layer on the surface of the carrier core material include an immersion method in which a powder of the carrier core material is immersed in the solution for forming the coating layer, and a solution for forming the coating layer on the surface of the carrier core material. Spraying method for spraying, fluidized bed method for spraying the solution for forming the coating layer in a state where the carrier core material is floated by flowing air, and a kneader for mixing the carrier core material and the coating layer forming solution in a kneader coater to remove the solvent. Examples of the coater method include a powder coat method in which a coating resin is finely divided and mixed in a carrier core material and a kneader coater at a temperature equal to or higher than the melting point of the coating resin and cooled to form a coating. The kneader coater method and the powder coating method are particularly preferably used.

  The average film thickness of the resin coating layer formed by the above method is usually 0.1 to 10 μm, preferably 0.2 to 5 μm.

  The core material (carrier core material) used in the electrostatic latent image developing carrier of the present invention is not particularly limited, and is a magnetic metal such as iron, steel, nickel or cobalt, or a magnetic oxide such as ferrite or magnetite. Glass beads and the like can be mentioned, but from the viewpoint of using the magnetic brush method, a magnetic carrier is desirable. As an average particle diameter of a carrier core material, generally 10-100 micrometers is preferable and 20-80 micrometers is more preferable.

  The mixing ratio (weight ratio) of the electrophotographic toner of the present invention and the carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and 3: 100 to 20: A range of about 100 is more preferable.

<Image forming method>
Next, an image forming method using the electrophotographic developer of the present invention will be described. In the image forming method, a latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member, and a toner image is formed from the electrostatic latent image formed on the surface of the latent image holding member using a developer containing toner. A developing step, a transfer step for transferring the toner image formed on the surface of the latent image holding member to the surface of the transfer member such as paper, and a fixing step for fixing the toner image transferred to the surface of the transfer member. The toner for electrophotography of the present invention is used as toner particles of the electrostatic charge image developer. As the latent image holding member, for example, an electrophotographic photosensitive member and a dielectric recording member can be used.

  In the case of an electrophotographic photosensitive member, the surface of the electrophotographic photosensitive member is uniformly charged by a corotron charger, a contact charger or the like and then exposed to form an electrostatic latent image (latent image forming step).

  Next, the electrostatic latent image formed on the latent image carrier is developed with toner composed of colored particles containing at least a binder resin and a colorant to form a toner image. In electrophotography, A developer layer is formed on the surface of the developer carrier disposed opposite to the latent image carrier, and the electrostatic latent image formed on the surface of the latent image carrier is developed by the developer layer. In the case of a two-component development system comprising a toner and a carrier, the developer layer is formed by a so-called magnetic brush in which a magnetic carrier is formed in the form of a brush on the surface of the developer carrying member and the toner adheres to this (development process).

  The formed toner image is transferred onto the surface of a transfer medium such as paper using a corotron charger or the like. In this case, in addition to transferring the toner image obtained in the developing process to the transfer material as it is, it is possible to use an intermediate transfer member, and a means for transferring the toner image to the transfer material after being transferred to the intermediate transfer member.

  When a full color image is to be obtained, a toner image developed using toner of at least three colors of cyan, magenta and yellow and, if necessary, four colors of black in the development process is laminated and transferred. Is done. At this time, using an intermediate transfer material, once transferring these layers onto the intermediate transfer member, it is preferable to transfer them to the transfer member at once in order to obtain an image with no positional deviation and good color development. It is.

When a single color image is to be obtained, the toner weight (TMA) in the 100% area area of the transfer image transferred onto the transfer material in the transfer step is preferably 0.80 mg / cm ² or less, and 0.60 mg. / Cm ² or less is more preferable (transfer process).

  Further, the toner image transferred to the surface of the transfer target is heat-fixed by a heating type fixing device, and a final toner image is formed. Examples of the heating type fixing device include a contact heating type fixing method using a heating roll or the like, and a non-contact heating type fixing method using oven heating. However, a contact type fixing device should be used from the viewpoint of reliability, safety, and thermal efficiency. Is preferred. The contact-type fixing device here refers to a fixing device of a type in which a fixing member such as a fixing roll presses a transfer material on which a transfer image is formed to fix the transfer image on the transfer material. A contact-type fixing device can be widely used. As a method of pressure contact, a transfer material on which a transfer image is formed is passed between two contacting rolls or between a contacting roll and a belt, and the transfer image is formed in a roll-roll or roll-belt nip region. And a method of fixing by pressing (fixing step).

  Examples of the transfer target (recording material) to which the toner image is transferred include plain paper and OHP sheet used for electrophotographic copying machines, printers, and the like.

  In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer object is as smooth as possible. For example, coated paper in which the surface of plain paper is coated with a resin or the like, art paper for printing Etc. can be used suitably.

  By using the electrophotographic toner of the present invention, fixing at a significantly lower temperature is possible than before, energy consumption in the fixing process and warm-up time can be greatly reduced, and the formed image is excellent. Preservability can also be realized. Further, since the toner has excellent fluidity and transferability, an image with excellent image quality can be formed, and charging can be stabilized.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In the description of the following examples, “parts” means parts by mass unless otherwise specified.

-Preparation of crystalline polyester resin (1)-
・ Into a heat-dried three-necked flask ・ 125 parts of ethylene glycol ・ 22.5 parts of sodium dimethyl 5-sulfoisophthalate ・ 215 parts of dimethyl sebacate ・ 0.31 parts of dibutyltin oxide (catalyst) The inside air was brought into an inert atmosphere with nitrogen gas, and stirred at 180 ° C. for 5 hours by mechanical stirring. Thereafter, the temperature was gradually raised to 220 ° C. under reduced pressure, and the mixture was stirred for 2.5 hours. When it became viscous, it was air-cooled, the reaction was stopped, and 222 parts of crystalline polyester resin (1) was synthesized. .

  The weight average molecular weight (Mw) of the obtained crystalline polyester resin (1) was 13500 and the number average molecular weight (Mn) was 6100 by molecular weight measurement (polystyrene conversion) by gel permeation chromatography (GPC). .

  Further, the melting point (Tm) of the crystalline polyester resin (1) was measured by the above-described measuring method using a differential scanning calorimeter (DSC). As a result, the crystalline polyester resin (1) had a clear peak and the peak top temperature (melting point). Was 72 ° C.

  The content ratio of the copolymerization component (5-sulfoisophthalic acid component) and the sebacic acid component, measured and calculated from the NMR spectrum of the resin, was 7.5: 92.5.

-Preparation of resin particle dispersion (1)-
200 parts of crystalline polyester resin (1) is put in 800 parts of distilled water, and the mixture is stirred with a homogenizer (manufactured by IKA Japan: Ultra Tarax) while being heated to 85 ° C. to obtain a resin particle dispersion (1). Obtained.

-Preparation of crystalline polyester resin (2)-
In a heat-dried three-necked flask,
-40 parts of 1,20-eicosanediol-2.7 parts of sodium dimethyl 5-sulfoisophthalate-20 parts of dimethyl sulfoxide-0.07 part of dibutyltin oxide (catalyst) Under an inert atmosphere with nitrogen gas, stirring was performed at 180 ° C. for 3 hours by mechanical stirring. Dimethyl sulfoxide was distilled off under reduced pressure, 31.4 parts of dimethyl dodecanedioic acid was added under a nitrogen stream, and the mixture was stirred at 180 ° C. for 1 hour.

  Thereafter, the temperature was gradually raised to 220 ° C. under reduced pressure, and the mixture was stirred for 45 minutes. When the mixture became viscous, it was air-cooled, the reaction was stopped, and 65 parts of crystalline polyester resin (2) was synthesized.

  The weight average molecular weight (Mw) of the obtained crystalline polyester resin (2) was 21000, and the number average molecular weight (Mn) was 9400, as determined by GPC molecular weight measurement (polystyrene conversion). Further, when the melting point (Tm) of the crystalline polyester resin (2) was measured by DSC using the above-described measurement method, it had a clear peak and the peak top temperature was 91 ° C. The content ratio of the copolymerization component (5-sulfoisophthalic acid component) and the dodecanedioic acid component measured and calculated from the NMR spectrum of the resin was 7.7: 92.3.

-Preparation of resin particle dispersion (2)-
150 parts of crystalline polyester resin (2) is put in 850 parts of distilled water, and the mixture is stirred and mixed with a homogenizer (IKA Japan: Ultra Tarax) while heating to 99 ° C. to obtain a resin particle dispersion (2). Obtained.

-Preparation of amorphous polymer dispersion (1)-
-Styrene: 740 parts-n-butyl acrylate: 60 parts-Acrylic acid: 8 parts-Dodecanethiol: 48 parts-Carbon tetrabromide: 8 parts Kasei Co., Ltd .: Nonipol 400) 12 parts and anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) 20 parts by weight dissolved in 1000 parts of ion-exchanged water were dispersed in a flask. After emulsifying and slowly mixing for 10 minutes, 100 parts of ion-exchanged water having 8 parts of ammonium persulfate dissolved therein was added thereto, and after replacing with nitrogen, the contents were brought to 70 ° C. while stirring the flask. It heated in the oil bath until it became, and emulsion polymerization was continued as it was for 5 hours. Thus, an amorphous polymer dispersion (1) (resin particle concentration: 40) obtained by dispersing resin particles having a volume average particle size of 180 nm, a glass transition point of 59 ° C., and a weight average molecular weight (Mw) of 15,000. % By weight) was prepared.

-Preparation of colorant dispersion (1)-
After mixing and dissolving 500 parts of a cyan pigment (manufactured by Dainichi Seika Co., Ltd .: ECB-301), 40 parts of an anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK) and 1460 parts of ion-exchanged water, a homogenizer ( A colorant dispersion liquid (1) obtained by dispersing the colorant (cyan pigment) was prepared using IKA: Ultra Tarax.

-Preparation of release agent dispersion (1)-
Mix 700 parts of release agent (Riken Vitamin Co., Ltd .: Riquemar B-200, melting point: 68 ° C.), 30 parts of anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK) and 1270 parts of ion-exchanged water. While being heated to 90 ° C. on a bath, the mixture was dispersed using a homogenizer (manufactured by IKA: Ultra Tarax) to prepare a release agent dispersion.

-Preparation of electrophotographic toner (1)-
1600 parts of resin particle dispersion (1), 55 parts of colorant dispersion (1), 101 parts of release agent dispersion, 5 parts of calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.), 200 parts of ion-exchanged water, and round stainless steel After accommodating in a flask and adjusting to pH 4.0, the mixture was dispersed using a homogenizer (manufactured by IKA: Ultra Tarrax T50) and then heated to 55 ° C. with stirring in an oil bath for heating. After maintaining at 55 ° C. for 3 hours, observation with an optical microscope confirmed that aggregated particles having a volume average particle diameter of about 5.0 μm were formed. After maintaining heating and stirring at 55 ° C. for another hour, observation with an optical microscope confirmed that aggregated particles having a volume average particle diameter of about 5.5 μm were formed.

  To this aggregated particle dispersion, 130 parts of the amorphous polymer dispersion (1) was added while stirring was continued. The pH at this time was 3.8. Therefore, an aqueous solution obtained by diluting sodium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) to 0.5% by mass was gently added to adjust the pH to 5.0. The agglomerated particle dispersion was heated to 65 ° C. while being stirred, held for 30 minutes, further heated to 80 ° C. and held for 60 minutes, and then observed with an optical microscope. Toner particles were observed. Thereafter, the temperature was lowered to 20 ° C. at a rate of 100 ° C./min while adding ion-exchanged water to solidify the particles.

  Thereafter, the reaction product was filtered, sufficiently washed with ion-exchanged water, and then dried using a vacuum dryer to obtain electrophotographic colored particles (1).

  The obtained electrophotographic colored particles (1) were measured using a Coulter counter [TA-II] type (aperture diameter: 50 μm, manufactured by Coulter Inc.), and found to have a volume average particle diameter of 6.1 μm and a number average particle diameter. Was 5.2 μm. When the particles were observed with an optical microscope, the shape was spherical.

  The electrophotographic colored particles (1) are subjected to a surface hydrophobization treatment, silica fine particles having a volume average particle size of 40 nm (hydrophobic silica manufactured by Nippon Aerosil Co., Ltd .: RX50) 0.8% by mass, 100 parts of metatitanic acid and isobutyltrimethoxysilane. 40 parts of the reaction product treated with 10 parts of trifluoropropyltrimethoxysilane and 1.0% by mass of metatitanic acid compound fine particles having a volume average particle diameter of 20 nm were added and mixed for 5 minutes using a Henschel mixer. Thereafter, it was sieved with a 45 μm sieving mesh to produce an electrophotographic toner (1).

-Preparation of electrophotographic toner (2)-
1600 parts of a resin particle dispersion (2), 55 parts of a colorant dispersion (1), 101 parts of a release agent dispersion, 5 parts of calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.), 200 parts of ion-exchanged water, and round stainless steel After being accommodated in a flask made and adjusted to pH 4.0, the mixture was dispersed using a homogenizer (manufactured by IKA: Ultra Tarrax T50) and heated to 78 ° C. in a heating oil bath while stirring. After maintaining at 78 ° C. for 3 hours, observation with an optical microscope confirmed that aggregated particles having a volume average particle diameter of 4.2 μm were formed. After further heating and stirring at 78 ° C. for 1 hour, observation with an optical microscope confirmed that aggregated particles having a volume average particle diameter of 5.2 μm were formed.

  The pH of this aggregated particle dispersion was 3.7. Therefore, an aqueous solution obtained by diluting sodium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) to 0.5% by mass was gently added to adjust the pH to 5.0. Further, 130 parts of the coated resin particles (1) were added, and then sodium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) was slowly added to adjust the pH to 7.2. The aggregated particle dispersion was heated to 97 ° C. and kept for 50 minutes while continuing to stir, and then observed with an optical microscope, whereby coated spherical particles were observed. Thereafter, the temperature was lowered to 20 ° C. at a rate of 100 ° C./min while adding ion-exchanged water to solidify the particles.

  Thereafter, the reaction product was filtered, sufficiently washed with ion-exchanged water, and then dried using a vacuum dryer to obtain electrophotographic colored particles (2).

  The obtained electrophotographic colored particles (2) were measured using a Coulter counter [TA-II] type (aperture diameter: 50 μm, manufactured by Coulter, Inc.), and found to have a volume average particle diameter of 5.9 μm and a number average particle diameter. Was 4.8 μm. When the particles were observed with an optical microscope, the shape was spherical.

  The obtained electrophotographic colored particles (2) were stirred and mixed with an external additive in the same manner as in the preparation example of the electrophotographic toner (1) to obtain an electrophotographic toner (2).

-Preparation of electrophotographic toner (3)-
Round 1600 parts of resin particle dispersion (1), 55 parts of colorant dispersion (1), 101 parts of release agent dispersion (1), 5 parts of calcium chloride (manufactured by Wako Pure Chemical Industries), and 200 parts of ion-exchanged water. The sample was placed in a stainless steel flask and dispersed using a homogenizer (manufactured by IKA: Ultra Tarrax T50), and then heated to 80 ° C. with stirring in an oil bath for heating. When an aqueous solution in which 5 parts of calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 100 parts of ion-exchanged water is added over 3 hours and observed with an optical microscope, particles having a volume average particle diameter of 5.6 μm are formed. It was confirmed that Further, 130 parts of the amorphous polymer dispersion (1) was added, and kept at 80 ° C. for 80 minutes with stirring. Thereafter, the temperature was lowered to 20 ° C. at a rate of 100 ° C./min while adding ion-exchanged water to solidify the particles.

  After cooling, an aqueous solution in which sodium carbonate (manufactured by Wako Pure Chemical Industries) was diluted to 0.5% was gently added to adjust the pH to 5.1. Thereafter, the reaction product was filtered, sufficiently washed with ion-exchanged water, and then dried using a vacuum dryer to obtain electrophotographic colored particles (3).

  The obtained electrophotographic colored particles (3) were measured using a Coulter counter [TA-II] type (aperture diameter: 50 μm, manufactured by Coulter, Inc.). The volume average particle diameter was 5.8 μm, and the number average particle diameter was Was 4.5 μm. When the particles were observed with an optical microscope, the shape was spherical.

  The obtained electrophotographic colored particles (3) were stirred and mixed with an external additive in the same manner as in the preparation example of the electrophotographic toner (1) to obtain an electrophotographic toner (3).

-Preparation of electrophotographic toner (4)-
An electrophotographic colored particle (4) was obtained in the same manner as the electrophotographic colored particle (1) except that the cooling rate was 10 ° C./min.

  The obtained electrophotographic colored particles (4) were measured using a Coulter counter [TA-II] type (aperture diameter: 50 μm, manufactured by Coulter), and found to have a volume average particle diameter of 6.2 μm and a number average particle diameter. Was 5.5 μm. When the particles were observed with an optical microscope, the shape was spherical.

  The obtained electrophotographic colored particles (4) were stirred and mixed with an external additive in the same manner as in the preparation example of the electrophotographic toner (1) to obtain an electrophotographic toner (4).

-Preparation of electrophotographic toner (5)-
The electrophotographic colored particles (5) are obtained in the same manner as the electrophotographic colored particles (1) except that the particles coalesced and coated at 80 ° C are cooled to 20 ° C at a rate of 0.1 ° C / min. It was.

  The obtained electrophotographic colored particles (5) were measured using a Coulter counter [TA-II] type (aperture diameter: 50 μm, manufactured by Coulter, Inc.), and found to have a volume average particle diameter of 6.1 μm and a number average particle diameter. Was 4.9 μm. When the particles were observed with an optical microscope, the shape was spherical.

-Preparation of electrophotographic toner (6)-
The colored particles for electrophotography (6) are obtained in the same manner as the colored particles for electrophotography (3) except that the particles which are coalesced and coated at 80 ° C. are cooled to 20 ° C. at a rate of 0.1 ° C./min. It was.

  The obtained electrophotographic colored particles (6) were measured using a Coulter counter [TA-II] type (aperture diameter: 50 μm, manufactured by Coulter, Inc.), and found to have a volume average particle diameter of 6.0 μm and a number average particle diameter. Was 5.0 μm. When the particles were observed with an optical microscope, the shape was spherical.

  The obtained electrophotographic colored particles (6) were stirred and mixed with an external additive in the same manner as in the preparation example of the electrophotographic toner (1) to obtain an electrophotographic toner (6).

-Carrier manufacturing-
Carbon black (trade name; VXC-72, manufactured by Cabot) 0.25 part was mixed with 2.5 parts of toluene, and a trifunctional isocyanate 80% by mass ethyl acetate solution ( Takenate D110N (manufactured by Takeda Pharmaceutical Co., Ltd.) 2.5 parts of the coating agent resin solution and Mn—Mg—Sr ferrite particles (volume average particle size: 35 μm) were added to a kneader and mixed and stirred at room temperature for 5 minutes. Then, the temperature was raised to 150 ° C. at normal pressure to distill off the solvent. After further 30 minutes of mixing and stirring, the heater was turned off and the temperature was lowered to 50 ° C. The obtained coated carrier was sieved with a 75 μm mesh to prepare a carrier.

<Example 1>
-Measurement and evaluation of powder cohesion (toner blocking resistance)-
Using a powder tester (manufactured by Hosokawa Micron Co., Ltd.), screens with 53, 45 and 38 μm openings are arranged in series from the top, and 2 g of electrophotographic toner (1) accurately weighed on the 53 μm sieve is charged. Then, vibration is applied for 90 seconds with an amplitude of 1 mm, and the toner weight on each sieve after vibration is measured, added with a weight of 0.5, 0.3, and 0.1, and calculated as a percentage. did. The sample (electrophotographic toner (1)) was left to stand for about 24 hours in an environment of 45 ° C./50% RH, and the measurement was performed in an environment of 25 ° C./50% RH. The results are shown in Table 1. In the present invention, the powder cohesion can be used without any practical problem as long as the weight of the toner after vibration is 40 or less, but is preferably 30 or less, more preferably 20 or less.

Further, the surface of each electrophotographic toner obtained in Examples 1 to 4 and Comparative Examples 1 to 2 was evaluated by the BET value. The evaluation criteria are as follows. The results are shown in Table 1.
○: BET value is less than 2.0 g / m ² .
X: BET value is 2.0 g / m ² or more.

-Production of electrophotographic developer (1)-
5 parts of electrophotographic toner (1) and 95 parts of carrier were placed in a V blender and stirred for 20 minutes, followed by sieving with a 105 μm mesh to prepare electrophotographic developer (1).

-Image quality (fogging) evaluation-
The obtained electrophotographic developer (1) is placed in DocuColor 1250 (manufactured by Fuji Xerox Co., Ltd.), copied at 50000 sheets in an environment of 25 ° C./50% RH, and solid after printing 50000 sheets. The image quality of the fixed image was visually evaluated according to the following evaluation criteria. The results are shown in Table 1.

[Image quality evaluation criteria]
○: No fogging and no problem △: Some fogging was observed but no practical problem ×: Large fogging was observed and practically unusable

-Evaluation of the core-shell interface-
The cross sections of the respective electrophotographic toners obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were observed and evaluated with a transmission electron microscope. The evaluation criteria are as follows. The results are shown in Table 1.
○: The core-shell interface adheres and no voids are observed.
Δ: Some voids are observed at the core-shell interface.
X: Many voids are confirmed at the core-shell interface.

Further, the surface of each electrophotographic toner obtained in Examples 1 to 4 and Comparative Examples 1 and 2 after printing 50,000 sheets was magnified and observed with an SEM and evaluated. The evaluation criteria are as follows. The results are shown in Table 1.
○: The core-shell structure is maintained, and the shell is not peeled off.
Δ: It has a core-shell structure, but it is confirmed that a small hole is opened in the shell.
X: The core-shell structure collapses, and peeling of the shell is confirmed.

  From the results of Table 1, in the measurement and evaluation of the powder cohesion (toner blocking resistance), all of Examples 1 to 4 and Comparative Examples 1 and 2 showed good powder cohesion. However, since the powder cohesiveness is superior to those of Comparative Examples 1 and 2, the surface of the electrophotographic toner is kept covered with the shell layer, and the surface is smooth so that the powder cohesion is further improved. It can be seen that the performance is improved.

  In the image quality evaluation, in Examples 1 to 4, good image quality without fogging was obtained at the initial stage and after printing 50000 sheets. In contrast, Comparative Example 1 did not provide good image quality after printing 50000 sheets. When the surface of the toner after printing 50000 sheets was magnified and observed with an SEM, Examples 1 to 4 were in a state where a good coating layer was retained, whereas Comparative Examples 1 and 2 were portions where the coating layer was peeled off. Since the core-shell structure collapsed and surface irregularities were generated, embedding of the external additive and generation of fine powder due to the shell material were observed.

  In the evaluation of the adhesion state of the core shell, after 50,000 sheets were printed, no voids were observed between the core shells in Examples 1 to 4 from the TEM observation results, but significant voids were confirmed in Comparative Examples 1 and 2. It was. Further, it can be seen from the comparison between Example 1 and Example 3 that good toner characteristics can be obtained regardless of the aggregation process / unification process or process.

-Preparation of crystalline polyester resin dispersion (3)-
In a heat-dried three-necked flask, an acid component of 90.5 mol% of 1,10 dodecanedioic acid, 2 mol% of sodium dimethyl-5-sulfonate, 7.5 mol% of 5-t-butylisophthalic acid, 9 Nonanediol 100 mol% and Ti (OBu) ₄ (0.014% by weight with respect to the acid component) as a catalyst were added, and the air in the container was depressurized by depressurization and further inert with nitrogen gas. Under an atmosphere, reflux was performed at 180 ° C. for 6 hours with mechanical stirring. Thereafter, excess ethylene glycol was removed by distillation under reduced pressure, the temperature was gradually raised to 220 ° C., and the mixture was stirred for 4 hours. When the mixture became viscous, the molecular weight was confirmed by GPC, and the weight average molecular weight became 13000. The distillation under reduced pressure was stopped and air-cooled to obtain crystalline polyester (3).

  Next, 80 parts of this crystalline polyester (3) and 720 parts of deionized water are placed in a stainless beaker, placed in a warm bath, and heated at 95 ° C. for 3 hours. When the crystalline polyester resin is melted, the mixture is stirred at 8000 rpm using a homogenizer (manufactured by IKA: Ultra Turrax T50). Next, while adding 20 g of an aqueous solution obtained by diluting 1.6 parts of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK), the emulsion is dispersed and a crystalline polyester resin having a volume average particle size of 0.15 μm. Dispersion liquid (3) [resin particle concentration: 10 mass%] was prepared.

-Preparation of crystalline polyester resin dispersion (4)-
In a heat-dried three-necked flask, an acid component of 90.5 mol% of 1,10 dodecanedioic acid, 2 mol% of sodium dimethyl-5-sulfonate, 7.5 mol% of 5-t-butylisophthalic acid, 9 Nonanediol 100 mol% and Ti (OBu) ₄ (0.014% by weight with respect to the acid component) as a catalyst were added, and the air in the container was depressurized by depressurization and further inert with nitrogen gas. Under an atmosphere, reflux was performed at 180 ° C. for 6 hours with mechanical stirring. Then, excess ethylene glycol was removed by distillation under reduced pressure, and the temperature was gradually raised to 220 ° C. and stirred for 4 hours. When the mixture became viscous, the molecular weight was confirmed by GPC, and the weight average molecular weight became 25000. The distillation under reduced pressure was stopped and air-cooled to obtain crystalline polyester (4).

  Next, 80 parts of this crystalline polyester (4) and 720 parts of deionized water are placed in a stainless beaker, placed in a warm bath and heated to 95 ° C. When the crystalline polyester resin is melted, the mixture is stirred at 8000 rpm using a homogenizer (manufactured by IKA: Ultra Turrax T50). Next, while 20 parts of an aqueous solution obtained by diluting 1.6 parts of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK) is added dropwise, the emulsion is dispersed and a crystalline polyester having a volume average particle size of 0.15 μm. Resin dispersion (4) [resin particle concentration: 10% by mass] was prepared.

-Preparation of crystalline polyester resin dispersion (5)-
To a heat-dried three-necked flask, 92.5 mol% dimethyl sebacate and 7.5 mol% 5-t-butylisophthalic acid, ethylene glycol (2 mol times the acid component), and Ti (as a catalyst) OBu) ₄ (0.012% by weight with respect to the acid component), and then the pressure in the container is reduced by depressurization, and the atmosphere is inerted with nitrogen gas. Reflux was performed for 5 hours. Then, excess ethylene glycol was removed by distillation under reduced pressure, the temperature was gradually raised to 230 ° C., and the mixture was stirred for 2 hours. When the mixture became viscous, the molecular weight was confirmed by GPC, and the weight average molecular weight became 20000. Now, 0.02 mol of trimellitic acid is added, the reaction proceeds for 30 minutes after the trimellitic acid melts, and heating is stopped. Further, in a viscous state, it was poured into an excess amount of methanol, reprecipitated and purified, and subjected to an acid value treatment, a weight-average molecular weight of 20000 and an acid value of 8 mg KOH / g (by JIS K 0070-1992 potentiometric titration method). Polyester (5) was obtained.

  Next, 80 parts of this crystalline polyester (5) and 720 parts of deionized water are placed in a stainless beaker, placed in a warm bath and heated to 95 ° C. When the crystalline polyester resin is melted, the mixture is stirred at 8000 rpm using a homogenizer (manufactured by IKA: Ultra Turrax T50). Then, 15 parts of an aqueous solution obtained by diluting 1.2 parts of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK) is added while emulsifying and dispersing, and a crystalline polyester resin having a volume average particle size of 0.15 μm. Dispersion liquid (5) [resin particle concentration: 10% by mass] was prepared.

-Preparation of crystalline polyester resin dispersion (6)-
To a heat-dried three-necked flask, 92.5 mol% dimethyl sebacate and 7.5 mol% 5-t-butylisophthalic acid, ethylene glycol (2 mol times the acid component), and Ti (as a catalyst) OBu) ₄ (0.012% by weight with respect to the acid component), and then the pressure in the container is reduced by depressurization, and the atmosphere is inerted with nitrogen gas. Reflux was performed for 5 hours. Then, excess ethylene glycol was removed by distillation under reduced pressure, the temperature was gradually raised to 230 ° C., and the mixture was stirred for 2 hours. When the mixture became viscous, the molecular weight was confirmed by GPC, and the weight average molecular weight became 13000. Now, 0.02 mol of trimellitic acid is added, the reaction proceeds for 30 minutes after the trimellitic acid melts, and heating is stopped. Further, in a viscous state, it was poured into an excessive amount of methanol, purified by reprecipitation, and subjected to acid value treatment, a weight average molecular weight of 13,000 and an acid value of 108 mg KOH / g (according to JIS K 0070-1992 potential difference titration method). Polyester (6) was obtained.

  Next, 80 parts of this crystalline polyester (6) and 720 parts of deionized water are placed in a stainless beaker, placed in a warm bath and heated to 95 ° C. When the crystalline polyester resin melted, the mixture was stirred at 8000 rpm using a homogenizer (manufactured by IKA: Ultra Tarrax T50). Next, while 20 parts of an aqueous solution obtained by diluting 1.6 parts of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK) is added dropwise, the emulsion is dispersed and a crystalline polyester having a volume average particle size of 0.18 μm. Resin dispersion (6) [resin particle concentration: 10% by mass] was prepared.

-Preparation of amorphous styrene acrylic polymer dispersion (2)-
-Styrene: 312 parts-n-butyl acrylate: 88 parts-Acrylic acid: 6 parts-Dodecanethiol: 8 parts A mixture of the above and dissolved is a nonionic surfactant (manufactured by Sanyo Kasei Co., Ltd .: Nonipol 400) ) 6 parts and 10 parts of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) dissolved in 560 parts of ion-exchanged water were dispersed in a flask, emulsified, and mixed slowly for 10 minutes. Then, 50 parts of ion-exchanged water in which 4 parts of ammonium persulfate was dissolved was added thereto, and after nitrogen substitution, the contents in the flask were heated in an oil bath until the temperature reached 70 ° C. while stirring the flask. The emulsion polymerization was continued as it was. Thus, an amorphous styrene acrylic polymer dispersion (2) (resin particle concentration) in which resin particles having a volume average particle size of 100 nm, a glass transition point of 52 ° C., and a weight average molecular weight (Mw) of 31,000 are dispersed. : 40% by mass).

-Preparation of amorphous polyester polymer dispersion (3)-
100 parts of amorphous PES resin F and 800 parts of ion-exchanged water were adjusted to pH 8 with ammonia water, and mixed at 140 ° C. using a disperser modified from Eurotech Emulsifier Cavitron CD1010 to a high temperature and high pressure type. An amorphous resin F dispersion having a partial concentration of 10% and a particle diameter of 0.7 μm in the resin dispersion was prepared.
An amorphous polyester polymer dispersion (3) (resin particle concentration: 20% by mass) in which resin particles having a glass transition point of 60 ° C. and a weight average molecular weight (Mw) of 15,000 were dispersed was prepared.

-Preparation of release agent dispersion (2)-
・ Paraffin wax (Nippon Seiwa Co., Ltd .: HNP9, melting point 77 ° C.): 50 parts ・ Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 5 parts ・ Ion-exchanged water: 200 parts or more Is heated to 110 ° C. and dispersed using a homogenizer (manufactured by IKA: Ultra Tarrax T50), then dispersed with a Manton Gorin high-pressure homogenizer (Gorin), and a release agent having a volume average particle diameter of 210 nm. A release agent dispersion (2) (release agent concentration: 20% by mass) was prepared.

-Preparation of colorant dispersion (2)-
・ Cyan pigment (Daiichi Seika Co., Ltd., Pigment BLue 15: 3 (copper phthalocyanine))
: 100 parts, anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R): 15 parts, ion-exchanged water: 900 parts The above is mixed, dissolved, and a high-pressure impact disperser Ultimateizer (Sugino Machine Co., Ltd.) A colorant dispersion liquid (2) obtained by dispersing the colorant (cyan pigment) by dispersing for about 1 hour using HJP 30006). The volume average particle diameter of the colorant (cyan pigment) in the colorant dispersion (2) was 0.15 μm, and the colorant particle concentration was 23% by mass.

(Example 5)
-Production of toner base particles (7)-
Crystalline polyester resin dispersion (3): 965 parts Colorant dispersion: 15.22 parts Nonionic surfactant (IGEPAL CA897 manufactured by Rhône-Poulenc): 1.42 parts 5 L cylindrical stainless steel container The mixture was dispersed and mixed for 5 minutes while applying a shearing force at 6000 rpm with an Ultraturrax. Subsequently, 3 parts of a 10% aqueous nitric acid solution of polyaluminum chloride (3% relative to the toner solid content) was added as a flocculant. At this time, in order to increase the viscosity, the raw material was sufficiently stirred with Ultraturrax, and when it became uniform, it was set in a polymerization kettle. The temperature was once raised to 40 ° C. with a mantle heater, and the pH was set to 4.6. Thereafter, 1N sodium hydroxide was added in order to suppress rapid aggregation that occurred with the temperature rise, and the temperature was gradually raised to 55 ° C. while controlling the particle size while raising the pH. When the temperature was 55 ° C., the volume average particle diameter was 5.6 μm.

Furthermore, the temperature was raised to 60 ° C. in order to incorporate the fine particles in the solution into the aggregated particles. Next, in order to fuse the aggregated particles and prevent the aggregated particles from being dispersed, the pH was adjusted to 6.9, the stirring speed was decreased from 200 rpm to 120 rpm, and the temperature was raised to 80 ° C.
After confirming that the particles were fused with a microscope (hereinafter, the fused particles are abbreviated as “core fused particles”), the pH was lowered to 6.5 while maintaining the temperature at 80 ° C. In order to stop, ice water was poured and rapidly cooled at a cooling rate of 100 ° C./min.

  The core fusion particle dispersion thus prepared was once concentrated in a centrifuge so that the solid concentration was 40% by mass. For the purpose of coating the surface of the core fused particles with the amorphous polymer, 56.5 parts of the amorphous polymer dispersion (2) is added, and the pH is lowered to 3.5. For the purpose of promoting the adhesion of molecular fine particles and then impregnating the surface of the core fusion particles with the flocculant component, 1.13 parts of flocculant (polyaluminum chloride 10% nitric acid aqueous solution) is added to the solid content of the shell material. 5%) Subsequently, in order to promote the fusion of the amorphous polymer particles on the surface of the core fusion particles, the mixture was kept at 55 ° C. for 10 hours, then raised to pH 7.0, washed and dried. Thereafter, sieving, washing and drying were performed to obtain a toner (7) having a volume average particle size of 6.0 μm.

(Examples 6, 7, 9, 10, 11)
According to the composition of Table 2, toners of Examples 6, 7, 9, 10, and 11 were obtained in the same manner as Example 5.

(Example 8)
A toner was obtained in the same manner as in Example 5 except that the amorphous polymer dispersion (3) was used instead of the amorphous polymer dispersion (2).

  The core fusion particle dispersion thus prepared was once concentrated in a centrifuge so that the solid concentration was 15 wt%. In order to coat the surface of the core fused particle with an amorphous polymer, an amorphous polymer dispersion is added and the pH is lowered to 3.5 to promote the adhesion of the amorphous polymer fine particles to the surface of the core fused particle. Next, for the purpose of impregnating the surface of the core fusion particles with the flocculant component, a flocculant (polyaluminum chloride 10% nitric acid aqueous solution) is added, and then the fusion of amorphous polymer particles on the surface of the core fusion particles is promoted. To maintain the temperature, the temperature was maintained at 55 ° C. for 10 hours, and the pH was raised to 7.0, followed by washing and drying. Thereafter, sieving, washing and drying were performed to obtain a comparative toner.

<Various toner evaluation>

1) Resistance
After compression molding 4 g of toner powder and seasoning a disk-shaped object under high temperature and high humidity (28 ° C./85% RH) for 10 hours, the volume resistance was measured using an R8340A high resistance meter manufactured by Advantest Corporation. The measurement was performed under the condition of 500V application.

2) Dynamic complex viscosity When the toner sample for measurement is set in the measuring device, the set temperature is set to 10 to 20 ° C. higher than the melting point of the crystalline resin contained in the toner, and this is cooled to 0 ° C. Then, heating was performed at a temperature rising rate of 1 ° C./min, and the dynamic complex modulus at the time of temperature rising was measured every 10 ° C. to 1 ° C.
The measurement apparatus used a rheometer (Rheometric Scientific Co., Ltd .: ARES rheometer), and measured the temperature rise using a parallel plate (8 mmφ) at a frequency of 1 rad / sec.

3) Particle size measuring method of binder resin fine particles, colorant particles, and release agent particles The particle size of binder resin fine particles, colorant particles, and release agent particles is determined by a laser diffraction particle size distribution analyzer (LA-700). Measured by HORIBA).

4) Measuring method of toner particle size and particle size distribution For the toner particle size and particle size distribution index, Coulter Counter TAII (manufactured by Beckman-Coulter) is used, and the electrolyte is ISOTON-II (manufactured by Beckman-Coulter). Measured using. As a measurement method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of sodium alkylbenzenesulfonate, which is a surfactant, as a dispersant. This is added to 100 to 150 ml of the electrolytic solution.
The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of particles of 0.6 to 18 μm is measured by using the Coulter counter TAII type with an aperture diameter of 30 μm. Volume average distribution and number average distribution were determined. For the particle size range (channel) obtained by dividing the measured particle size distribution, a cumulative distribution is drawn from the small diameter side to each of the volume and the number, and the particle size at which accumulation is 16% is defined as D16v and D16p. % Particle size was defined as D50v and D50p, respectively. Further, similarly defined as D84v and D84p, respectively. Using these, the volume average particle size distribution index (GSDv) was determined from D84v / D16v, and the number average particle size index (GSDp) was calculated from D84p / D16p.

5) Toner shape factor measurement method The toner shape factor SF1 is obtained by taking an optical microscope image of toner dispersed on a slide glass into a Luzex image analyzer through a video camera, and squaring / projecting the maximum length of 50 or more toners. It calculated | required by calculating an area (ML2 / A) and calculating | requiring an average value.

6) Measuring method of molecular weight and molecular weight distribution of binder resin In the toner of the present invention, the molecular weight distribution of the binder resin is performed under the following conditions. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)”, and the column uses two “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)” THF (tetrahydrofuran) was used as an eluent. As experimental conditions, the sample concentration was 0.5%, and the flow rate was 0.6 ml / min. The experiment was conducted using a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

7) Charge amount 1.5 parts by weight of each electrostatic charge image developing toner and 30 parts by weight of resin-coated ferrite particles prepared in the evaluation of fixability were weighed in a glass bottle with a lid, and subjected to high temperature and high humidity ( After seasoning for 24 hours at a temperature of 28 ° C. and a humidity of 85%, the mixture was stirred and shaken with a turbula mixer for 5 minutes. The charge amount (μc) of the toner under this environment was measured with a blow-off charge amount measuring device (manufactured by Toshiba Chemical Corporation: TB200).

8) Melting point measurement The melting points (Tm) of the crystalline polyester resins (3) to (6) and the amorphous polymers (2) to (3) were measured by a differential scanning calorimeter (manufactured by Mac Science: DSC3110, thermal analysis system). (001) (hereinafter abbreviated as “DSC”). The measurement was performed from room temperature to 150 ° C. at a heating rate of 10 ° C. per minute, and the melting point was obtained by analyzing according to JIS standards (see JIS K-7121).
In addition, all the half value width in the endothermic peak of crystalline polyester resin (3)-(6) is 6 degrees C or less, and it was confirmed that it has crystallinity. In addition, since amorphous polymers (2) to (3) did not have a clear melting point, they showed a glass transition point (Tg).

<Evaluation of toner fixing property, charging property and transfer property>
(Evaluation of fixability)
To each toner base particle, 2.5 parts of spherical silica (average primary particle size 140 nm, sol-gel method, hexamethyldisilazane treatment, sphericity Ψ0.90) is added to 100 parts as an external additive, and the peripheral speed is increased with a 20 L Henschel mixer. Blend for 40 minutes at 10 m / s, then add 1.2 parts of rutile titanium oxide (primary particle size 20 nm, m) n-decyltrimethoxysilane treatment), and blend at a peripheral speed of 40 m / s for 5 minutes. Thereafter, coarse particles were removed using a sieve having an opening of 45 μm to obtain a toner for developing an electrostatic image.
Next, 5 parts by weight of each of these toners and 100 parts by weight of resin-coated ferrite particles (average particle size 35 μm) were mixed to prepare a two-component developer, which was then used as a commercially available electrophotographic copying machine (Fuji Xerox DocuColor1250). ) Was used to obtain an unfixed image.

  Subsequently, using an external fixing device, the fixing temperature of the image and the hot offset property were evaluated while gradually increasing the fixing temperature between 90 ° C. and 220 ° C. The low-temperature fixability is determined by fixing an unfixed solid image (25 mm × 25 m) and then bending it with a weight under a certain load, grading the degree of image defect in that portion, and fixing the fixing temperature to a certain grade or higher. The lowest fixing temperature was used as an index for low-temperature fixability.

(Evaluation of chargeability)
1.5 parts by weight of each electrostatic charge image developing toner and 30 parts by weight of resin-coated ferrite particles (volume average particle diameter 35 μm) prepared during the evaluation of the fixing property are weighed in a glass bottle with a lid, After seasoning for 24 hours under humidity (temperature 28 ° C., humidity 85%) and low temperature and low humidity (temperature 10 ° C., humidity 15%), the mixture was shaken with a turbula mixer for 5 minutes. The charge amount (μc) of the toner in both environments was measured with the blow-off charge amount measuring device.

[Evaluation of transferability]
Using a developer using cyan toner, primary and secondary transfer efficiencies were evaluated with Docu color 1250 (manufactured by Fuji Xerox Co., Ltd.) in an environment of 20 ° C. and 50% RH. As a method, a solid patch of 5 × 2 cm is developed, and the developed image on the photoreceptor is measured by tape transfer and the weight (W1) is measured. Next, the same patch is transferred to the intermediate transfer member, and the weight (W2) of the transferred image is measured. Further, a similar solid patch is transferred onto paper (J paper, manufactured by Fuji Xerox Office Supply), and the weight (W3) of the transferred image is measured. According to each measured value, the primary and secondary transfer efficiencies are calculated according to the formula {(primary transfer efficiency) = W2 / W1 × 100 (%)} and {(secondary transfer efficiency) = W3 / W2 × 100 (%)}. The transferability was evaluated. The evaluation conditions were primary transfer current: 20 μA, secondary transfer voltage: 1.5 kV, the developing machine was placed in the black position, printed in black mode, and evaluated.
The results are shown in Table 2.

From the results shown in Table 2, in Examples 5 to 11, since the BET specific surface area is small and the shell layer has no irregularities or holes, the external additive works efficiently, the transfer rate is good, the image quality is excellent, the fixability, The charging property was also excellent.
-Preparation of crystalline polyester resin dispersion (7) In a heat-dried three-necked flask, 124 parts of ethylene glycol, 22.2 parts of sodium dimethyl 5-sulfoisophthalate, 213 parts of dimethyl sebacate, and dibutyltin oxide 0 as a catalyst After adding 3 parts by weight, the air in the container was placed in an inert atmosphere with nitrogen gas by depressurization, and the mixture was stirred at 180 ° C. for 5 hours by mechanical stirring. Thereafter, the temperature was gradually raised to 220 ° C. under reduced pressure, and the mixture was stirred for 2 hours. When it became viscous, it was air-cooled, the reaction was stopped, and 220 parts of crystalline polyester resin (7) was synthesized.
The weight average molecular weight (MW) of the obtained crystalline polyester resin (7) was 11000 and the number average molecular weight (Mn) was 4700 by molecular weight measurement (polystyrene conversion) by gel permeation chromatography (GPC). .
Further, when the melting point (Tm) of the crystalline polyester resin (7) was measured by a differential scanning calorimeter (DSC) by the above-described measuring method, it had a clear peak and the peak top temperature was 69 ° C. Met.
The content ratio of the copolymerization component (5-sulfoisophthalic acid component) and the sebacic acid component, measured and calculated from the NMR spectrum of the resin, was 7.5: 92.5.

-Preparation of amorphous resin dispersion (4)-
<Preparation of amorphous resin particle dispersion (4)>
Styrene 340 parts n-Butyl acrylate 60 parts Acrylic acid 8 parts Dodecanethiol 8 parts Divinyl adipate 1 part The above components were mixed and dissolved to obtain a nonionic surfactant (manufactured by Sanyo Kasei Co., Ltd .: Nonipol 400) 8 Part and anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) dissolved in 550 parts of ion-exchanged water, dispersed in a flask, emulsified and mixed slowly for 10 minutes. 50 parts of ion-exchanged water in which 4 parts of ammonium persulfate was dissolved was added to the flask and the atmosphere was replaced with nitrogen. Then, the contents in the flask were heated in an oil bath until the temperature reached 70 ° C. while stirring, and the emulsion polymerization was continued for 5 hours. Continued. Thereafter, the reaction solution was cooled to room temperature to prepare a resin particle dispersion (4) in which resin particles having a glass transition point of 60.5 ° C. and a weight average molecular weight of 29000 were dispersed.

-Preparation of release agent dispersion (3)-
・ Paraffin wax (Nippon Seiwa Co., Ltd .: HNP9, melting point 77 ° C)
Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 5g
・ Ion exchange water: 200g
The above components were heated to 110 ° C. and dispersed using a homogenizer (manufactured by IKA: Ultra Tarrax T50), then dispersed with a Manton Gorin high-pressure homogenizer (Gorin), and the average particle size was 225 nm. A release agent dispersion (3) (release agent concentration: 22.5% by mass) obtained by dispersing the mold was prepared.

-Preparation of colorant dispersion (3)-
150 parts of crystalline polyester resin (7) is put in 850 parts of distilled water, and heated and mixed at 80 ° C. with a homogenizer (manufactured by IKA Japan: Ultra Tarax) to stir resin particle dispersion (1). Obtained. Next, 250 parts of a phthalocyanine pigment (manufactured by Dainichi Seika Co., Ltd .: PV FAST BLUE), 20 parts of an anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK), and 730 parts of ion-exchanged water are mixed and dissolved. After that, a colorant dispersion (3) was prepared by dispersing using a homogenizer (manufactured by IKA: Ultra Tarax) to disperse the colorant (phthalocyanine pigment).

(Example 12)
-Production of toner particles (14)-
-Crystalline polyester resin dispersion (7): 400 parts-Anionic surfactant (Taika Power BN2060) 6.4 parts-Colorant dispersion (3): 18.8 g
Nonionic surfactant (IGEPAL CO897): 1.34 parts Release agent dispersion (3): 41.8 parts The above four components excluding the anionic surfactant are put into a 5 L cylindrical stainless steel container and removed there. After adding 285 parts of ionic water and heating to 80 ° C., the anionic surfactant was added, and the mixture was held for 30 minutes with stirring at 150 rpm, and then allowed to cool to room temperature.
Next, 2.74 parts of a 10% nitric acid aqueous solution of polyaluminum chloride as a flocculant was added to the raw material mixture brought to room temperature, and homogenized for 5 minutes while applying a shearing force at 6000 rpm with Ultraturrax to prepare a raw material dispersion. At this time, nitric acid was added, and dispersion mixing was performed while controlling the pH of the raw material to 4.1. At this time, if the pH is less than 4.0, rapid particle growth occurs, so the pH of the raw material dispersion was controlled within the above range. Further, since the raw material dispersion was thickened, it was sufficiently stirred and when it became uniform, it was set in a polymerization kettle equipped with a stirrer and a thermometer.

Next, in order to form core agglomerated particles, the temperature was increased at 1 ° C. per minute with a mantle heater while maintaining the stirring speed at 500 rpm, and when the temperature reached 40 ° C., the stirring speed was increased to 530 rpm. Thereafter, the temperature was further increased, the aggregation growth of the core aggregate particles was promoted, and when the temperature reached 55 ° C., the temperature increase was stopped, and the stirring speed was reduced to 450 rpm and held for 1 hour. Subsequently, in order to stop the growth of the particle diameter of the core aggregated particles, the pH was increased to 8.3, and the stirring rotation speed was further decreased to 200 rpm.
Subsequently, in order to fuse the core aggregated particles, the temperature was raised to 75 ° C. and held at 75 ° C. for 10 minutes. In this state, after confirming that the core agglomerated particles were fused and the core fused particles were obtained with a microscope, in order to stop the growth of the particle size of the core fused particles, ice water was injected and the cooling rate was 100 ° C./min. It was cooled quickly.
The volume average particle size (D ₅₀ ) of the obtained core fused particles was measured with a Coulter counter (TAII, manufactured by Beckman-Coulter), and it was 5.8 μm. Furthermore, the shape factor SF1 of this particle was measured using a Luzex image analyzer (manufactured by Nireco, LUZEXIII).
120.

-Washing core fusion particles with acidic solution-
The core fused particle slurry thus prepared was heated to 40 ° C., then nitric acid was added to adjust the pH to 3.0, and the mixture was stirred for 1 hour, followed by filtration. Thereafter, the core fusion particles were again dispersed with ion exchange water at 35 to 40 ° C., which is 6 times the weight of the toner particles, stirred, and then filtered.

-Amorphous resin particle shell formation process-
The acid-washed and ion-exchanged water-washed core fused particles were concentrated with a centrifuge so that the solid concentration was 20% or more. Next, 60 parts of the amorphous polymer dispersion is added to the core fused particles and stirred for 1 hour. Furthermore, after adding 100 parts of ion-exchange water and stirring, pH was adjusted to 3.0. Subsequently, 0.5 part of a flocculant (polyaluminum chloride 10% nitric acid aqueous solution) is added to adhere the amorphous polymer particles to the surface of the core fused particles, and the temperature is raised to 48 ° C. and held for 2 hours. Agent (IGEPAL CA897 manufactured by Rhône-Poulenc): 2.29 parts are added, and the temperature is raised to 53 ° C. and held again for 2 hours. Further, in order to promote the fusion of the amorphous polymer particles on the surface of the fused particles, the temperature was raised to 57 ° C., held for 10 hours, and then cooled to room temperature.

-Core shell toner cleaning-
The resulting toner slurry having a core-shell structure is heated to 40 ° C., an aqueous sodium hydroxide solution is added to adjust the pH to 9.0, stirred for 1 hour, and then filtered to remove the surfactant attached to the shell surface. . The toner slurry after alkali washing is filtered, then dispersed with ion exchange water at 35 to 40 ° C. in an amount 6 times the toner particle weight, stirred for 20 minutes, and filtered again. The washing process is repeated 3 times using this ion exchange water. Next, the filtered toner is dispersed at 35 to 40 ° C., which is 6 times the weight of the toner particles, and the pH is adjusted to 3.5 using nitric acid, followed by stirring for 1 hour to remove sodium on the shell surface. Subsequently, the acid-washed toner slurry is filtered, then again washed with 6 times the amount of ion-exchanged water at 35 to 40 ° C. with respect to the weight of the toner particles, filtered and dried to obtain toner particles (14). Got.

The obtained toner particles (14) were measured with a fluorescent X analysis analyzer, whereby the amount of sodium in the toner particles was 0.07 atomic% with respect to the total amount of oxygen and carbon. Further, the amount of sodium on the toner surface as measured by XPS was 0.31 atomic% with respect to the total amount of oxygen and carbon.

The volume average particle size (D ₅₀ ) of the toner particles of Example 12 was measured and found to be 6.1 μm. Furthermore, using a Luzex image analyzer, the shape factor SF1 of the particles was measured and found to be 129. The specific surface area of the toner particles was measured using a specific surface measuring instrument (Flow Soap II 2300: manufactured by Micromethris Co., Ltd.), which was 1.7. The specific surface area was determined using the particle count for each channel of the Coulter Counter. The calculated value was 1.06. As a result, the surface property index value was 1.46. Further, when the surface of the toner particles was observed by SEM, it was a smooth surface without holes.

(Example 13)
-Production of toner particles (15)-
Core fusion particles were prepared under the same conditions as in Example 1, and the battlefield was performed by adjusting the pH to 5.0 in the washing process of the core fusion particles. Thereafter, an amorphous resin particle shell was formed under the same conditions as in Example 1, washed and dried to obtain toner particles (15).

The obtained toner particles (15) were measured with a fluorescent X-ray analyzer, whereby the amount of sodium in the toner particles was 0.26 atomic% with respect to the total amount of oxygen and carbon. Further, the amount of sodium on the toner surface as measured by XPS was 0.28 atomic% with respect to the total amount of oxygen and carbon.

The volume average particle size (D ₅₀ ) of the toner particles of Example 13 was measured and found to be 6.16 μm. Furthermore, using a Luzex image analyzer, the shape factor SF1 of the particles was measured and found to be 128. Further, when the surface property index value was determined in the same manner as in Example 1, it was 1.68. Further, when the surface of the toner particles was observed by SEM, it was a smooth surface without holes.

[Evaluation of electrification]
Toner particles 14 and 15 are each added 1 part of titania fine powder as an external additive to 100 parts of toner and 0.6 part of silica fine powder and mixed with a Henschel mixer to obtain toners 14 and 14 for developing electrostatic images. It was. Each 1.5 parts of the electrostatic image developing toner 14 and 15 and 30 parts by weight of resin-coated ferrite carrier particles (average particle size 35 μm) are weighed in a glass bottle with a lid, and are hot and humid (temperature 28 ° C., humidity 85%). ), And seasoning at low temperature and low humidity (temperature 10 ° C., humidity 15%) for 24 hours, and then stirred with a turbula mixer for 5 minutes. The charge amount (μC / g) of the toner in both environments was measured.

[Evaluation of powder flowability]
The electrostatic image developing toners 14 and 15 produced during the chargeability evaluation are placed in an electrophotographic copying machine (A-Color 635 modified machine manufactured by Fuji Xerox Co., Ltd.) and continuously driven, and developed from a toner cartridge in one minute. The mass of the toner conveyed to the machine was measured, and the powder fluidity was evaluated. There is no problem in practical use because the transported toner mass is 15 g or more.

[Evaluation of heat storage property of toner]
The toner was allowed to stand for 24 hours in an environment of 50 ° C. and 50% RH, and the amount of toner remaining on the 106 μm mesh was measured to evaluate the thermal storage property of the toner. There is no problem in practical use because the remaining toner amount% is 5% or less.

[Evaluation of fixability]
Two-component developer is prepared by mixing 8 parts by weight of each of the electrostatic image developing toners 14 and 15 prepared during the evaluation of the chargeability and 100 parts by weight of a resin-coated ferrite carrier (average particle size 35 μm). This was imaged using a commercially available electrophotographic copying machine (A-Color 635 manufactured by Fuji Xerox Co., Ltd.) to obtain an unfixed image.
Subsequently, using a belt nip type external fixing machine, the fixing temperature of the image and the hot offset property were evaluated while the fixing temperature was gradually raised between 90 ° C. and 220 ° C. The low-temperature fixability is that after fixing an unfixed solid image (25 mm x 25 mm), it is bent using a weight with a constant load (1 kg), and the fixing temperature at which the image defect width is 80 μm or less is the minimum fixing temperature. As an indicator of low-temperature fixing.

[Evaluation of cleaning properties]
10 parts of each of the electrostatic image developing toners 14 and 15 produced during the evaluation of the chargeability and 100 parts of resin-coated ferrite particles (volume average particle diameter 35 μm) are mixed with a blender to prepare a two-component developer. did. Further, these developers are put into an electrophotographic copying machine (A-Color 635 manufactured by Fuji Xerox Co., Ltd.), and a DC test component bias of 30,000 copies is DC component -500 V, an AC superimposition component is Vp-p 1.5 kV, and a frequency is 6 kHz. A rectangular wave superimposed one was applied to the developing sleeve and a print test was performed. Cleaning was performed by pressing a urethane rubber blade against the surface of the photoreceptor.

  Table 3 shows the core internal sodium amount, surface sodium amount, charging characteristics, surface property index value, shape factor, fixing characteristics, and cleaning characteristics of the toner particles 14 and 15 thus prepared.

Since the toner particles of Examples (12) and (13) are produced through the washing process of the core fusion particles, the sodium on the core surface is removed, the adhesion of the amorphous resin particles becomes uniform, and uneven portions and holes are not formed. This is because no smooth surface was formed. In addition, Examples (12) and (13) have high chargeability. This is because sodium on the toner surface can be sufficiently removed by the toner particle cleaning step. In addition, Examples (12) and (13) can be fixed at a low temperature and have an excellent cleaning characteristic as compared with an indeterminate shape factor of 125 or more.

It is a figure which shows the characteristic of bridge | crosslinking-type crystalline resin used as binder resin.

Claims (4)

  In a method for producing an electrophotographic toner, wherein the surface of colored particles comprising at least a binder resin and a colorant is coated with an amorphous resin, the binder resin has a melting point of 50 to 100 ° C. and a weight average molecular weight of 12,000 or more. It is a crystalline polyester resin of 50000 or less, and a dispersion of binder resin particles and a dispersion of colorant particles are mixed, and an aggregating agent is added to form the aggregated particles of the binder resin particles and the colorant particles. An aggregating step, an attaching step for attaching amorphous resin particles to the surface of the agglomerated particles, a coalescing step for coalescing the agglomerated particles at a temperature equal to or higher than the melting point of the binder resin, and at a rate of at least 10 ° C / min And a cooling step of lowering the temperature to a temperature equal to or lower than the crystallization temperature of the binder resin.   An electrophotographic toner obtained by the production method according to claim 1.   A developer comprising the toner according to claim 2 and a carrier.   A latent image forming step for forming an electrostatic latent image on the surface of the latent image holding member, and a developing step for developing the electrostatic latent image formed on the surface of the latent image holding member with a developer containing toner to form a toner image. An image forming method comprising: a transfer step of transferring a toner image formed on the surface of the latent image holding member to a transfer target; and a fixing step of fixing the toner image transferred to the surface of the transfer target. An image forming method, wherein the developer is the developer according to claim 3.

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