JP2008225094A - Toner for electrostatic charge image development - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development, the toner having excellent durability and blocking resistance and causing no precipitation of a release agent by phase separation even when the toner is left to stand in a high temperature environment for a long time. <P>SOLUTION: The toner for electrostatic charge image development contains a binder resin, a colorant, a charge control agent and a fatty acid ester compound. The fatty acid ester compound is a fatty acid ester compound of a fatty acid and a polyhydric alcohol mixture containing at least polyhydric alcohols with from four to eight functional groups, wherein the proportion of a fatty acid ester compound having four or less functional groups is at most 10 wt.%, the proportion of a fatty acid ester compound having eight or more functional groups is at least 15 wt.%, at least 90% of fatty acid residues have 20 to 50 carbon atoms, and the hydroxyl value is at most 8.0 mgKOH/g. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic charge image developing toner used for developing an electrostatic latent image formed on a photoreceptor in an electrophotographic (including electrostatic printing) image forming apparatus. More specifically, the present invention contains a fatty acid ester compound that acts as a release agent, and is excellent in fixability, storage stability (blocking resistance), durability (continuous printing characteristics), and the like, and phase separation of the fatty acid ester compound The present invention relates to a toner for developing an electrostatic charge image, in which precipitation due to water is suppressed.

  In an image forming apparatus such as an electrophotographic copying machine or printer in which an electrostatic charge image developing toner is used, there are increasing demands for higher printing speed, lower fixing temperature, and full color. By lowering the fixing temperature of the electrostatic image developing toner, it is possible to cope with high-speed printing and full-color printing, and power consumption can be reduced. On the other hand, if the toner composition is designed so as to lower the fixing temperature of the electrostatic image developing toner, the toner composition tends to aggregate and the blocking resistance is lowered.

  For example, in order to obtain a toner for developing an electrostatic image having good low-temperature fixability, a method of incorporating a low softening point substance having releasability such as paraffin wax is known. However, the toner for developing an electrostatic charge image containing such a low softening point substance is likely to aggregate during storage, and in addition to lowering the blocking resistance, the durability against continuous printing may be reduced, and the image quality may be reduced. Or drop.

  Conventionally, in order to obtain a toner for developing an electrostatic image having an excellent balance between low-temperature fixability and blocking resistance (storage stability) and capable of high-quality printing, the toner contains a fatty acid ester compound of a polyhydric alcohol. Various methods have been proposed.

  For example, JP-A-4-194948 (Patent Document 1) is obtained by blending a glycerol- (meth) acrylate copolymer containing a high molecular weight component and a low molecular weight component with a polyglycerin partial ester compound. A resin composition for toner is disclosed. Toner powder can be obtained by pulverizing the resin composition for toner. The polyglycerin partial ester is rapidly melted by heating to lower the melt viscosity of the toner and improve the fluidity at low temperature. The OH group remaining in the polyglycerin partial ester increases the affinity with the paper and improves the low-temperature adhesion of the toner to the paper.

  However, since the polyglycerin partial ester described in Patent Document 1 has a large amount of OH groups remaining, the chargeability of the toner under high temperature and high humidity becomes unstable, making it difficult to obtain a sufficient image density. Cheap. Further, when a polymerized toner is produced using a polymerizable monomer composition containing a polyglycerin partial ester, in the droplet forming step of the polymerizable monomer composition in an aqueous medium, Due to the influence of the remaining OH groups, it is difficult to form droplets of a polymerizable monomer composition having a sharp particle size distribution, and thus it is difficult to obtain a polymerized toner having a sharp particle size distribution.

  Japanese Patent Application Laid-Open No. 2001-147550 (Patent Document 2) discloses that in a toner for developing an electrostatic charge image containing at least a binder resin, a colorant, and a polyfunctional ester compound, the polyfunctional ester compound is 5 per molecule. An electrostatic charge image developing toner having at least one ester bond, having a molecular weight of 2000 or more, a dissolution amount of 5 g or more in 100 g of styrene measured at 35 ° C., and an acid value of 2 mgKOH / g or less is disclosed. .

  Examples of Patent Document 2 show hexaglycerin tetrastearate tetrabehenate, hexaglycerin tetrastearate dibehenate, pentaerythritol tetrabehenate, and triglycerin pentastearate as polyfunctional ester compounds. ing. However, electrostatic charge image developing toners containing these polyfunctional ester compounds tend to aggregate when placed in a high-temperature atmosphere for a long time, and the anti-blocking property is not sufficient.

  Japanese Patent Application Laid-Open No. 2003-241418 (Patent Document 3) describes polyglycerol fatty acid esters of two or more fatty acids selected from saturated fatty acids having 8 to 22 carbon atoms and unsaturated fatty acids as low-temperature fixability for toner. A method for use as an anti-blocking agent is disclosed. However, the electrostatic image developing toner containing a polyglycerin fatty acid ester of two or more fatty acids disclosed in Patent Document 3 is inferior in continuous printing characteristics after being left in a high-temperature atmosphere and does not have sufficient blocking resistance. Absent.

  Japanese Patent Application Laid-Open No. 2006-98745 (Patent Document 4) discloses a polymerized toner containing an ester of a trivalent or higher alcohol and a fatty acid having 12 to 22 carbon atoms as a release agent. In Examples of Patent Document 4, dipentaerythritol hexamyristate and pentaerythritol tetrastearate are used as the ester. However, the toner for developing an electrostatic charge image containing these fatty acid ester compounds does not have sufficient continuous printing characteristics after being left in a high temperature atmosphere, and further improvement is required. In addition, in the toner for developing an electrostatic charge image containing these fatty acid ester compounds, whitening of the developing roll due to precipitation of the fatty acid ester compounds is observed, and contamination of each part of the apparatus and a tendency to decrease blocking resistance are observed.

JP-A-4-194948 JP 2001-147550 A JP 2003-241418 A JP 2006-98745 A

  In recent years, image forming apparatuses such as electrophotographic copying machines and printers are strongly required to be lighter, smaller, and more functional. Further, the integration of the image forming apparatus with other equipment such as a facsimile is being promoted, and a compact design is required to save space. For this reason, it exists in the tendency for the temperature inside an apparatus to become high. Further, image forming apparatuses are increasingly used in areas where the annual average temperature is high.

  Therefore, the electrostatic image developing toner is required to be excellent in durability and blocking resistance even when placed in a high temperature atmosphere for a long time. However, conventional electrostatic image developing toners containing fatty acid ester compounds cannot sufficiently meet these requirements.

  An object of the present invention is to develop an electrostatic charge image developing toner that is excellent in durability and blocking resistance even when placed in a high temperature atmosphere for a long time and that does not cause precipitation due to phase separation of a release agent. Is to provide.

  More specifically, the object of the present invention is to contain a fatty acid ester compound that acts as a mold release agent, and has excellent fixability, storage stability (blocking resistance), durability (continuous printing characteristics), etc., under a high temperature atmosphere. An object of the present invention is to provide a toner for developing an electrostatic charge image in which deterioration of these characteristics is suppressed even when left for a long time, and precipitation due to phase separation of a fatty acid ester compound is suppressed.

  As a result of diligent research to solve the above-mentioned problems, the present inventors are a fatty acid ester compound of a polyhydric alcohol mixture containing at least tetrafunctional to octafunctional polyhydric alcohol and a fatty acid, and having a specific composition And an electrostatic charge image developing toner containing a fatty acid ester compound having the above characteristics.

  The fatty acid ester compound used in the present invention plays a role of contributing to toner properties such as releasability and low-temperature fixability. The toner for developing an electrostatic charge image containing the fatty acid ester compound is found to have a low decrease in the number of continuous prints and a remarkably low degree of aggregation even when placed in a high temperature atmosphere for a long time. Thus, it is excellent in durability and blocking resistance. Further, the toner for developing an electrostatic charge image containing the fatty acid ester compound may cause whitening of the developing roll due to precipitation of the fatty acid ester compound during printing even when the toner is placed in a high temperature atmosphere for a long time. In addition, there is no contamination of each part of the apparatus or deterioration of the toner function. The present invention has been completed based on these findings.

According to the present invention, in the toner for developing an electrostatic image containing a binder resin, a colorant, a charge control agent, and a fatty acid ester compound, the fatty acid ester compound comprises:
(A) a fatty acid ester compound of a polyhydric alcohol mixture containing at least tetrafunctional to octafunctional polyhydric alcohol and a fatty acid;
(B) The content ratio of the tetrafunctional or lower fatty acid ester compound is 10% by weight or less,
(C) The content ratio of the fatty acid ester compound having 8 or more functional groups is 15% by weight or more,
(D) 90% or more of the fatty acid residues have 20 to 25 carbon atoms, and
(E) Provided is a toner for developing an electrostatic charge image, wherein the hydroxyl value is 8.0 mgKOH / g or less.

  According to the present invention, the toner for developing an electrostatic charge image is excellent in durability and blocking resistance even when placed in a high temperature atmosphere for a long time, and does not cause precipitation due to phase separation of the release agent. Is provided. In particular, according to the present invention, it contains a fatty acid ester compound that acts as a mold release agent, is excellent in fixability, storage stability, durability, etc., even when placed in a high temperature atmosphere for a long time. Thus, there is provided a toner for developing an electrostatic charge image, in which the deterioration of the various properties is suppressed and the precipitation due to phase separation of the fatty acid ester compound is suppressed.

  The fatty acid ester compound used in the present invention is a fatty acid ester compound of a polyhydric alcohol mixture containing at least tetrafunctional to octafunctional polyhydric alcohol and a fatty acid. As long as the requirements regarding the following composition are satisfied, the polyhydric alcohol mixture may contain 1 to 3 and / or 9 or more polyhydric alcohols. The fatty acid ester compound has a small hydroxyl value and is a substantially complete ester compound, not a partial ester compound of fatty acid.

  The fatty acid ester compound used in the present invention has a content of a tetrafunctional or lower fatty acid ester compound of 10% by weight or less, preferably 8% by weight or less, more preferably 5% by weight or less, and an 8 or more functional fatty acid. The content ratio of the ester compound is 15% by weight or more, preferably 18% by weight or more, more preferably 20% by weight or more. The fatty acid ester compound preferably contains a pentafunctional to heptofunctional fatty acid ester compound in a proportion of preferably 15% by weight or more, more preferably 18% by weight or more, and particularly preferably 20% by weight or more.

  In the fatty acid ester compound used in the present invention, 90% or more, preferably 95% or more, more preferably 98% or more of the fatty acid residues have 20 to 25 carbon atoms. The number of carbon atoms of the fatty acid residue is preferably 22 to 25, and in many cases 22.

  In the present invention, the ratio of each functional fatty acid ester compound and the ratio of the carbon number of the aliphatic residue are analytical values obtained by GC-MS (gas chromatography / mass spectrometry) measurement. The number of functional groups (OH groups) of the starting polyhydric alcohol and the number of carbons of the long-chain fatty acid are indicated by the number of functional groups and the number of carbons of the main component. It is necessary to actually measure these values.

  When the fatty acid ester compound used in the present invention has the selected composition, the object of the present invention can be achieved. If the content ratio of the tetrafunctional or lower fatty acid ester compound is too large or the content ratio of the octafunctional or higher fatty acid ester compound is too small, the durability and blocking resistance after standing in a high temperature atmosphere will be reduced, and the developing roll The whitening phenomenon is also seen. When the proportion of the fatty acid residue having 20 to 25 carbon atoms in the fatty acid ester compound is too small, the blocking resistance after leaving in a high temperature atmosphere is remarkably deteriorated or the durability is lowered. In addition, the whitening phenomenon of the developing roll occurs.

  The hydroxyl value of the fatty acid ester compound used in the present invention is 8.0 mgKOH / g or less, preferably 5.0 mgKOH / g or less, more preferably 3.0 mgKOH / g or less. When the hydroxyl value of the fatty acid ester compound is too high, when producing a polymerized toner, it has an adverse effect when granulating droplets of the monomer composition containing the fatty acid ester compound in an aqueous dispersion medium. It becomes difficult to granulate droplet particles having a uniform and stable distribution. In a toner containing a fatty acid ester compound having a high hydroxyl value, the chargeability under high temperature and high humidity becomes unstable, and it becomes difficult to obtain a sufficient image density.

  The solubility of the fatty acid ester compound used in the present invention in styrene is preferably 5 g or more, more preferably 10 g or more, and more preferably 10 g or more, when expressed in terms of the amount of styrene 100 g measured at 35 ° C. (g / 100 g ST; 35 ° C.). Preferably it is 15 g or more, particularly preferably 20 g or more. If the amount of the fatty acid ester compound dissolved in styrene at 35 ° C. is too small, the solubility of the fatty acid ester compound in a polymerizable monomer containing styrene as a main component generally decreases. Therefore, when the polymerized toner is produced, the content of the polyfunctional ester compound in the toner is insufficient, and it becomes difficult to sufficiently lower the fixing temperature. On the other hand, if the amount dissolved is too small, it is necessary to heat to a high temperature in order to dissolve a sufficient amount of the fatty acid ester compound in the polymerizable monomer. In addition, the fatty acid ester compound having an excessively small amount dissolved in styrene tends to disperse unevenly in the produced polymerized toner even when heated and dissolved in the polymerizable monomer.

  The average molecular weight of the fatty acid ester compound used in the present invention is preferably 2000 to 6000, more preferably 2300 to 4000, and particularly preferably 2500 to 3500. If the average molecular weight of the fatty acid ester compound is too low, it is difficult to lower the fixing temperature, and offset resistance becomes insufficient. If the average molecular weight of the fatty acid ester compound is too low, the melting point of the fatty acid ester compound itself becomes low, and the fatty acid ester compound is likely to precipitate (bleed) from the toner during storage of the toner or in a high temperature environment in the toner box of the developing device. As a result, the toner may agglomerate or the bleed-out fatty acid ester compound crystals may grow greatly. If the fatty acid ester compound is deposited during printing, each part of the apparatus is contaminated, which may cause toner filming on the developing roll, the photoreceptor surface, and the like. The average molecular weight of the fatty acid ester compound can be obtained as a standard polystyrene conversion value measured using gel permeation chromatography (GPC). The average molecular weight of the fatty acid ester can also be calculated by calculation from the average molecular weight (calculated value) of the polyhydric alcohol used for esterification and the molecular weight of the fatty acid.

  The fatty acid ester compound used in the present invention preferably exhibits a maximum endothermic peak in the region of 50 to 80 ° C. at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter. A fatty acid ester compound having a maximum endothermic peak temperature of 50 to 80 ° C. can contribute to the low-temperature fixability of the toner. The maximum endothermic peak temperature is preferably 55 to 78 ° C, particularly preferably 60 to 75 ° C.

  The fatty acid ester compound used in the present invention can be obtained by esterifying a polyhydric alcohol mixture containing at least tetrafunctional to octafunctional polyhydric alcohol and a fatty acid having 22 to 25 carbon atoms.

  The molecular weight of the polyhydric alcohol is preferably 100-1500, more preferably 200-1000, and particularly preferably 300-800. Therefore, the average molecular weight of the polyhydric alcohol mixture is also within the above range. A fatty acid ester compound using a polyhydric alcohol having a molecular weight that is too large tends to reduce the releasing effect of the fatty acid component.

  Examples of the polyhydric alcohol include glycerin dehydration condensate (polycondensate), carbohydrates or dehydration condensate thereof. Among these, glycerin polycondensate (polyglycerin) is preferable. Therefore, the polyhydric alcohol mixture is preferably a glycerin polycondensate mixture having a different degree of polycondensation. Glycerin and polyglycerin can be represented by the following formula.

  When n = 1, the monomer is a glycerin, and the number of hydroxyl groups (number of functional groups) is three. When n = 2, it is a dimer of glycerin, and the number of functional groups thereof is four. As n increases by 1, the number of functional groups increases by one. That is, the number of functional groups = 3 + (n−1). When n = 6, it is a glycerin hexamer, and the number of functional groups thereof is eight.

  When dehydrating polycondensation of glycerin, a mixture of glycerin polycondensates having different degrees of polymerization is obtained. In the present invention, it is preferable to use polyglycerin containing at least a dimer to hexamer glycerin polycondensate mixture as the polyhydric alcohol mixture. This polyglycerin may contain a glycerin monomer and / or a polyglycerin of 7-mer or more.

  As the polyglycerin, the fatty acid ester compound finally obtained has a content ratio of the tetrafunctional or lower fatty acid ester compound of 10% by weight or less and a content ratio of the octafunctional or higher fatty acid ester compound of 15% by weight or higher. Polyglycerin having a distribution of functional groups is used. Furthermore, the polyglycerin preferably has a functional group distribution capable of providing a fatty acid ester compound in which the content ratio of each of the pentafunctional to 7 functional fatty acid ester compounds is 15% by weight or more. . Such polyglycerin is dehydrated and polycondensed under conditions such that the average degree of polycondensation of glycerin is 6 or more, and polycondensation is performed so that the distribution from the diglycerin polycondensate to the decaglycerin polycondensate is broadened. It can be obtained by setting conditions.

  The fatty acid ester compound can be obtained by esterifying the polyglycerin and a fatty acid having 20 to 25 carbon atoms. The fatty acid having 20 to 25 carbon atoms is preferably a saturated fatty acid. In that case, it is preferable to use a high-purity saturated fatty acid so that the resulting fatty acid ester compound has the distribution of the number of functional groups as described above. Further, by using a high purity saturated fatty acid having 20 to 25 carbon atoms, a fatty acid ester compound in which 90% or more of the fatty acid residues have 20 to 25 carbon atoms can be obtained.

  The fatty acid is a saturated or unsaturated fatty acid having 20 to 25, preferably 22 to 24 carbon atoms, and more preferably a saturated fatty acid. Examples of such fatty acids include saturated higher fatty acids such as icosanoic acid (20 carbon atoms), behenic acid (22 carbon atoms), lignoceric acid (24 carbon atoms); higher unsaturated fatty acids such as erucic acid (22 carbon atoms). ; Among these, behenic acid is particularly preferable.

  When a fatty acid ester compound obtained using a fatty acid having a small number of carbon atoms is used, the durability of the toner for developing an electrostatic charge image held in a high-temperature atmosphere tends to decrease, the degree of aggregation increases, Whitening. It is preferable that the fatty acid used for the synthesis | combination of the fatty acid ester compound used by this invention is 1 type, and it is more preferable that it is only behenic acid. Conventionally, a fatty acid ester compound synthesized using two types of fatty acids having different carbon numbers has been considered preferable because the crystallinity is lowered and the amount of heat required for melting during toner fixing is reduced. However, when a fatty acid ester compound obtained by using a fatty acid having a carbon number of less than 20 and a fatty acid having a carbon number of 20 or more is used, the durability of the toner for developing an electrostatic charge image held in a high temperature atmosphere tends to decrease. In addition, the degree of aggregation is remarkably increased and the developing roll is whitened. Therefore, the fatty acid ester compound used in the present invention requires that 90% or more of the fatty acid residues have 20 to 25 carbon atoms.

  The fatty acid ester compound used in the present invention needs to increase the esterification reaction rate between a polyhydric alcohol such as polyglycerin and a fatty acid so that the hydroxyl value is 5 mgKOH / g or less. For this purpose, it is preferable to react an excess amount of fatty acid with the polyhydric alcohol during the esterification reaction and purify the reaction product.

  The fatty acid ester compound is used in an amount of usually 0.1 to 40 parts by weight, preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the binder resin or polymerizable monomer forming the binder resin. The amount is more preferably 1 to 20 parts by weight, particularly preferably 2 to 15 parts by weight. If the proportion of the fatty acid ester compound used is too small, it will be difficult to obtain a toner having excellent low-temperature fixability. When the ratio of the fatty acid ester compound used is too large, the offset resistance is reduced, toner filming on the surface of the photoconductor is likely to occur, or the toner is liable to deposit from the toner surface.

  The toner for developing an electrostatic charge image of the present invention may be colored resin particles containing a binder resin, a colorant, a charge control agent, and the fatty acid ester compound, and is not particularly limited by the production method. The colored resin particles are also called toner particles, and in the case of a polymerized toner, they may be called colored polymer particles. Examples of the method for producing the toner for developing an electrostatic image include a pulverization method and a polymerization method. Examples of the polymerization method include an emulsion polymerization method, an aggregation method, a dispersion polymerization method, and a suspension polymerization method. According to the polymerization method, micron-order toner particles can be obtained directly with a relatively small particle size distribution. The electrostatic charge image developing toner of the present invention may be a core-shell type toner (capsule toner) in which a resin coating layer is formed on the surface of colored resin particles. The toner for developing an electrostatic charge image of the present invention is particularly preferably a polymerized toner obtained by a suspension polymerization method from the viewpoint of developer characteristics.

  A polymerized toner by suspension polymerization suspends a polymerizable monomer composition containing at least a polymerizable monomer, a colorant, a charge control agent, and a fatty acid ester compound in an aqueous dispersion medium containing a dispersion stabilizer. It can be obtained by suspension polymerization. A polymer formed by polymerization of the polymerizable monomer serves as a binder resin. The polymerized toner having a core-shell structure can be produced by a method such as a spray dry method, an interfacial reaction method, an in situ polymerization method, or a phase separation method. In particular, the in situ polymerization method and the phase separation method are preferable because of high production efficiency. Specifically, it is obtained by suspension polymerization of a polymerizable monomer composition containing at least a polymerizable monomer, a colorant, and a fatty acid ester compound in an aqueous dispersion medium containing a dispersion stabilizer. It can be obtained by using the colored resin particles as a core and subjecting the polymerizable monomer for shell to suspension polymerization in the presence of the core. A polymer layer formed by polymerization of the shell monomer is a resin coating layer. The polymerizable monomer composition may contain various additives such as a crosslinkable monomer, a macromonomer, a molecular weight modifier, a general-purpose release agent, a lubricant, and a dispersion aid, as necessary. .

  As the polymerizable monomer, a monovinyl monomer is preferable. Specifically, styrene monomers such as styrene, vinyl toluene, α-methyl styrene; acrylic acid, methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, Acrylic acid or methacrylic such as dimethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dimethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide Derivatives of acids; Ethylenically unsaturated monoolefins such as ethylene, propylene and butylene; Vinyl halides such as vinyl chloride, vinylidene chloride and vinyl fluoride; Vinyls such as vinyl acetate and vinyl propionate Esters; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone and methyl isopropenyl ketone; nitrogen-containing vinyl compounds such as 2-vinyl pyridine, 4-vinyl pyridine and N-vinyl pyrrolidone; . Monovinyl monomers can be used alone or in combination of a plurality of monomers. Of the monovinyl monomers, it is preferable to use a styrene monomer and a (meth) acrylic acid derivative in combination.

  Use of a crosslinkable monomer and / or a crosslinkable polymer together with the polymerizable monomer is effective in improving hot offset resistance. The crosslinkable monomer is a monomer having two or more polymerizable carbon-carbon unsaturated double bonds, and examples thereof include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; Diethylenically unsaturated carboxylic acid esters such as methacrylate and diethylene glycol dimethacrylate; (meth) acrylates derived from aliphatic terminal alcohols such as 1,4-butanediol and 1,9-nonanediol; N, N-divinylaniline, di And divinyl compounds such as vinyl ether; compounds having three or more vinyl groups; and the like.

  Examples of the crosslinkable polymer include polyethylene, polypropylene, polyester and polysiloxane-derived (meth) acrylate having two or more hydroxyl groups in the molecule. These crosslinkable monomers and crosslinkable polymers can be used alone or in combination of two or more. The crosslinkable monomer and / or crosslinkable polymer is usually 10 parts by weight or less, preferably 0.01 to 5 parts by weight, more preferably 0.1 to 2 parts per 100 parts by weight of the polymerizable monomer. Used in parts by weight.

  When a macromonomer is used together with a polymerizable monomer, the balance between storage stability, offset prevention property and low-temperature fixability can be improved. A macromonomer is a relatively long linear molecule having a polymerizable functional group (for example, an unsaturated group such as a carbon-carbon double bond) at the end of a molecular chain. As the macromonomer, an oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000 is preferable. When a macromonomer having a small number average molecular weight is used, the surface portion of the toner particles becomes soft and the storage stability is lowered. On the other hand, if a macromonomer having a large number average molecular weight is used, the meltability of the macromonomer is poor, and the toner fixability is lowered.

  Specific examples of the macromonomer include styrene, a styrene derivative, a methacrylic acid ester, an acrylic acid ester, acrylonitrile, a methacrylonitrile, a polymer obtained by polymerizing two or more kinds alone, and a macromonomer having a polysiloxane skeleton. Etc. Among the macromonomers, a polymer having a glass transition temperature higher than the glass transition temperature of the binder resin is preferable, and a copolymer macromonomer or polymethacrylic acid ester macromonomer of styrene and methacrylic acid ester and / or acrylic acid ester is particularly preferable. Is preferred. When using a macromonomer, the blending ratio is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, more preferably 0.05 to 100 parts by weight with respect to 100 parts by weight of the polymerizable monomer. 1 part by weight. When the proportion of the macromonomer used is too large, the fixability tends to decrease.

  As the colorant, various pigments and dyes used in the field of toner such as carbon black and titanium white can be used. Examples of the black colorant include carbon black and nigrosine-based dyes and pigments; magnetic particles such as cobalt, nickel, iron tetroxide, manganese iron oxide, zinc iron oxide, and nickel iron oxide. When carbon black is used, it is preferable to use carbon black having a primary particle size of 20 to 40 nm because good image quality can be obtained and the safety of the toner to the environment is enhanced.

  As a color toner colorant, a yellow colorant, a magenta colorant, a cyan colorant, or the like can be used. Examples of the yellow colorant include C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 83, 90, 93, 97, 120, 138, 155, 180, 181; Nephthol Yellow S, Hansa Yellow G, C.I. I. Examples thereof include bat yellow.

  Examples of the magenta colorant include azo pigments and condensed polycyclic pigments. More specifically, for example, C.I. I. Pigment Red 48, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 149, 163, 170, 184, 185, 187, 202, 206, 207, 209, 251; C.I. I. Pigment violet 19 and the like.

  Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and the like. I. Pigment blue 2, 3, 6, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17, 60; phthalocyanine blue, C.I. I. Bat Blue, C.I. I. Acid blue and so on. The colorant is generally used in a proportion of 0.1 to 50 parts by weight, preferably 1 to 20 parts by weight, with respect to 100 parts by weight of the binder resin or the polymerizable monomer forming the binder resin.

  Examples of the molecular weight modifier include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan and n-octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride and carbon tetrabromide; These molecular weight modifiers can be added before the start of polymerization or during the polymerization. The molecular weight modifier is usually used in a proportion of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the polymerizable monomer.

  For uniform dispersion of the colorant, lubricants such as fatty acids such as oleic acid and stearic acid, fatty acid metal salts composed of fatty acids and metals such as Na, K, Ca, Mg and Zn; silane or titanium coupling agents Dispersion aids such as can be used. The lubricant and the dispersant are usually used in a ratio of about 1/1000 to 1/1 based on the weight of the colorant.

  In order to improve the chargeability of the toner, various positively chargeable or negatively chargeable charge control agents are used. Examples of the charge control agent include Bontron N01 (manufactured by Orient Chemical), Nigrosine Base EX (manufactured by Orient Chemical), Spiron Black TRH (manufactured by Hodogaya Chemical), T-77 (manufactured by Hodogaya Chemical), and Bontron S. -34 (made by Orient Chemical), Bontron E-81 (made by Orient Chemical), Bontron E-84 (made by Orient Chemical), Bontron E-89 (made by Orient Chemical), Bontron F-21 (Orient Chemical) COPY CHRGE NX VP434 (Clariant), COPY CHRGE NEG VP2036 (Clariant), TNS-4-1 (Hodogaya Chemical), TNS-4-2 (Hodogaya Chemical), LR-147 Charge control agents such as (made by Nippon Carlit Co., Ltd.); JP-A-11-15192, Quaternary ammonium (salt) group-containing copolymers described in Kaihei 3-175456, JP-A-3-243904, etc., JP-A-3-243594, JP-A-1-217464, JP-A-3-243 Charge control resins such as sulfonic acid (salt) group-containing copolymers described in Japanese Patent No. 15858 can be used. The charge control agent is usually used in a proportion of 0.01 to 10 parts by weight, preferably 0.1 to 7 parts by weight, with respect to 100 parts by weight of the binder resin or the polymerizable monomer forming the binder resin. .

  Since the fatty acid ester compound used in the present invention acts as a release agent, it is not necessary to use other release agents, but a general-purpose release agent may be included for the purpose of preventing offset, if desired. . Such release agents include, for example, low molecular weight polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; low molecular weight oxidized low molecular weight polypropylene, low molecular weight terminal-modified polypropylene having molecular ends substituted with epoxy groups Terminal-modified polyolefin waxes such as block polymers of these and low molecular weight polyethylene, low molecular weight oxidized low molecular weight polyethylene, low molecular weight polyethylene having molecular ends substituted with epoxy groups, and block polymers of these and low molecular weight polypropylene; Candelilla, Carnauba , Rice, wax, jojoba and other natural waxes; paraffin, microcrystalline, petrolactam and other petroleum waxes and modified waxes; montan, ceresin, ozokerite, etc. Synthetic waxes such as Fischer-Tropsch wax; mineral wax mixtures thereof and the like. When using these release agents, it is preferable to use them in a proportion of 0.1 to 20 parts by weight with respect to 100 parts by weight of the binder resin or the polymerizable monomer forming the binder resin. More preferably, it is used at a ratio of 15 parts by weight.

  As the polymerization initiator, a radical polymerization initiator is preferably used. Specifically, persulfates such as potassium persulfate and ammonium persulfate; 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2 '-Azobis-2-methyl-N-1,1-bis (hydroxymethyl) -2-hydroxyethylpropioamide, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azo Azo compounds such as bisisobutyronitrile and 1,1'-azobis (1-cyclohexanecarbonitrile); isobutyryl peroxide, 2,4-dichlorobenzoyl peroxide, 3,5,5'-trimethylhexanoyl Diacyl peroxides such as peroxides; bis (4-t-butylcyclohexyl) peroxydicarbonate, di-n-propylperoxydi- -Bonate, di-isopropyl peroxy di-carbonate, di-2-ethoxyethyl peroxy di-carbonate, di (2-ethyl ethyl peroxy) di-carbonate, di-methoxybutyl peroxy di-carbonate, di (3- Peroxydicarbonates such as methyl-3-methoxybutylperoxy) dicarbonate; (α, α-bis-neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1 ′, 3, 3'-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t- Hexyl peroxypivalate, t-butyl peroxypivalate Methyl peroxide, di-t-butyl peroxide, acetyl peroxide, dicumyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, di-isopropyl peroxide Other peroxides such as dicarbonate, di-t-butylperoxyisophthalate, and t-butylperoxyisobutyrate are exemplified. A redox initiator in which these polymerization initiators and a reducing agent are combined can also be used.

  Among these polymerization initiators, an oil-soluble radical initiator that is soluble in the polymerizable monomer is preferable, and a water-soluble initiator can be used in combination with the initiator if necessary. The use ratio of the polymerization initiator is usually 0.1 to 20 parts by weight, preferably 0.3 to 15 parts by weight, more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer. is there. If the use ratio is too small, the polymerization rate is slow, and if it is too large, the molecular weight is low, which is not preferable. The polymerization initiator can be added to the monomer composition in advance, but it is added to the suspension after completion of the granulation process of the monomer composition in the aqueous dispersion medium in order to avoid premature polymerization. You can also The use ratio of the polymerization initiator is usually about 0.001 to 3% by weight based on the aqueous dispersion medium.

  Examples of the dispersion stabilizer used in the present invention include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide. Products; metal hydroxides such as aluminum hydroxide, magnesium hydroxide and ferric hydroxide; water-soluble polymers such as polyvinyl alcohol, methylcellulose and gelatin; anionic surfactants, nonionic surfactants, amphoteric surfactants Surfactants such as agents; and the like. Among these, metal compounds such as sulfates, carbonates, metal oxides and metal hydroxides are preferable, and colloids of slightly water-soluble metal compounds are more preferable. In particular, colloids of poorly water-soluble metal hydroxides are suitable because the particle size distribution of toner particles can be narrowed and the sharpness of images is improved.

The colloid of the hardly water-soluble metal compound is not limited by its production method, but the colloid of the hardly water-soluble metal hydroxide obtained by adjusting the pH of the aqueous solution of the water-soluble polyvalent metal compound to 7 or more, particularly water-soluble A colloid of a poorly water-soluble metal hydroxide produced by a reaction in a water phase of a functional polyvalent metal compound and an alkali metal hydroxide is preferred. The colloid of a hardly water-soluble metal compound has a number particle size distribution D ₅₀ (50% cumulative value of the number particle size distribution) of 0.5 μm or less and a D ₉₀ (90% cumulative value of the number particle size distribution) of 1 μm or less. Preferably there is. When the particle size of the colloid becomes too large, the stability of polymerization is lost, and the storage stability of the toner is lowered.

  The dispersion stabilizer is preferably used in a proportion of 0.1 to 20 parts by weight, more preferably 0.3 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer. When this use ratio is too small, it becomes difficult to obtain sufficient polymerization stability, and polymerized aggregates are easily generated. On the other hand, if the use ratio is too large, the particle size distribution of the toner particles is broadened due to an increase in fine particles, or the viscosity of the aqueous solution is increased and the polymerization stability is lowered.

  In order to produce colored resin particles (colored polymer particles) by suspension polymerization, first, a polymerizable monomer, a colorant, and other additive components are mixed to prepare a polymerizable monomer composition. . Next, the polymerizable monomer composition is put into an aqueous medium containing a dispersion stabilizer and stirred with a high shearing force using a high-speed stirrer or the like, and the polymerizable monomer composition is added to the aqueous medium. A minute droplet is formed.

  In forming droplets of the polymerizable monomer composition, first, primary droplets having a volume average particle size of about 50 to 1000 μm are formed. In order to avoid premature polymerization, the polymerization initiator is preferably added to the aqueous dispersion medium after the primary droplet size in the aqueous medium becomes uniform. A polymerization initiator is added to and mixed with the suspension in which the primary droplets of the polymerizable monomer composition are dispersed in an aqueous dispersion medium, and the particle size of the droplets is adjusted using a high-speed rotary shearing stirrer. Stir until a small particle size close to the colored polymer particles. In this way, secondary droplets having a minute particle diameter of about 2 to 15 μm in volume average particle diameter are formed.

  The method of forming droplets is not particularly limited. For example, (in-line type) emulsifying disperser (trade name “Milder” manufactured by Ebara Manufacturing Co., Ltd.), high-speed emulsifier / disperser (made by Tokushu Kika Kogyo Co., Ltd., trade name “ TK homomixer MARK type II)).

  The polymerizable monomer composition dispersed as droplets in an aqueous medium is polymerized in the presence of a polymerization initiator to produce colored polymer particles. The polymerization temperature is usually 50 ° C. or higher, preferably 60 to 95 ° C. The reaction time of the polymerization is usually 1 to 20 hours, preferably 2 to 15 hours. The aqueous dispersion containing the produced colored polymer particles is filtered, and then the colored polymer particles are recovered through the steps of washing, dehydration, and drying.

  The polymerizable monomer used to form the colored polymer particles has a glass transition temperature Tg of a polymer obtained by polymerizing it of usually 80 ° C. or lower, preferably 40 to 80 ° C., more preferably 50 to 70. It is desirable to select so that it becomes ° C. By using the polymerizable monomer alone or in combination of two or more, the glass transition temperature of the polymer to be produced can be adjusted to a desired range.

  In the case of core-shell type colored polymer particles, the glass transition temperature of the polymer constituting the shell is preferably higher than the glass transition temperature of the polymer constituting the core colored polymer particle, more preferably 5 ° C or higher. It is particularly preferable that the temperature is 10 ° C. or higher. As the polymerizable monomer for the shell, styrene, methyl methacrylate, acrylonitrile, a mixture thereof and the like capable of forming a polymer having a high glass transition temperature exceeding 80 ° C. are preferable.

  Polymerization initiators used for the polymerization of the polymerizable monomer for shell include persulfate metal salts such as potassium persulfate and ammonium persulfate; 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propion Amido], 2,2′-azobis- [2-methyl-N- [1,1-bis (hydroxymethyl) 2-hydroxyethyl] propionamide] and other azo-based initiators; Can be mentioned. The addition amount of the polymerization initiator is preferably 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer for shell. The polymerization temperature of the shell layer is preferably 50 ° C. or higher, more preferably 60 to 95 ° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

  Since the aqueous dispersion containing colored polymer particles (including core-shell type) produced by polymerization contains a dispersion stabilizer, a large number of fine particles of the dispersion stabilizer adhere to the surface of the colored polymer particles. ing. When an inorganic compound such as an inorganic hydroxide that is soluble in acid is used as the dispersion stabilizer, acid is added to the aqueous dispersion containing the produced colored polymer particles, and the dispersion stabilizer is washed with water. Dissolve in and remove. When the dispersion stabilizer is an alkali-soluble inorganic compound, the alkali is added to the aqueous dispersion containing the colored polymer particles, and the dispersion stabilizer is dissolved in water and removed.

  For example, when a colloid of a poorly water-soluble metal hydroxide such as magnesium hydroxide colloid is used as a dispersion stabilizer, an acid such as sulfuric acid is added to the aqueous dispersion to solubilize the dispersion stabilizer in water (this Is called "acid cleaning"). The pH of the aqueous dispersion is usually adjusted to 6.5 or less, preferably 2 to 6.5, more preferably 3 to 6.0 by acid washing. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid; organic acids such as formic acid and acetic acid can be used.

  The aqueous dispersion obtained in the acid washing or alkali washing step is filtered to separate the colored polymer particles. Next, the colored polymer particles separated by filtration are washed with water, and the purified water is filtered. In the water washing step, it is preferred to wash the water with water until the electrical conductivity of the filtrate (filtered pre-purified water) is 1,000 μS / cm or less, and filter the pre-purified water. The water washing step may be repeated batchwise or continuously using a belt filter or the like. As a cleaning apparatus used for water cleaning, for example, it is preferable to use any one of a belt filter, a rotary filter, and a filter press, or a combination thereof. After the washing step, the wet colored polymer particles are dehydrated and dried by the dehydration step.

  The volume average particle diameter (Dv) of the toner for developing an electrostatic charge image (including core-shell type colored resin particles) of the present invention is usually 3 to 12 μm, preferably 5 to 11 μm, more preferably 6 to 10 μm. The particle size distribution represented by the ratio (Dv / Dp) of the volume average particle size (Dv) to the number average particle size (Dp) of the toner particles of the present invention is usually 1 or more and 1.7 or less, preferably It is 1.5 or less, more preferably 1.4 or less, and particularly preferably 1.3 or less. If the volume average particle diameter of the toner particles is too large, the resolution tends to be lowered. When the particle size distribution of the toner particles is large, the ratio of the toner particles having a large particle size increases, and the resolution tends to decrease.

  The average circularity of the toner particles of the present invention is preferably 0.960 to 0.995, more preferably 0.970 to 0.990. When the average circularity of the toner particles is too small, the fluidity and transferability of the electrostatic charge image developing toner are liable to deteriorate. When the average circularity of the toner particles is too large, the cleaning property of the toner remaining on the photoreceptor tends to be lowered. When the average circularity of the toner particles is within the above range, the fluidity, transferability, and cleaning properties of the electrostatic image developing toner are highly balanced.

The average circularity can be obtained by a ratio (L ₁ / L ₂ ) between the circumferential length L _{1 of the} circle equal to the projected area of the particle and the circumferential length L ₂ of the projected particle image. The average circularity is an average value of the circularity of each particle measured for toner particles having an equivalent circle diameter of 0.6 to 400 μm. The average circularity can be measured using a flow type particle image analyzer. The average circularity is an index indicating the degree of unevenness of the toner particle shape, and is 1.0 when the toner particles are completely circular, and the average circularity becomes smaller as the shape becomes more complicated.

  The average thickness of the shell in the core-shell type toner particles is usually 0.001 to 1 μm, preferably 0.003 to 0.5 μm, more preferably 0.005 to 0.2 μm, and particularly preferably 0.02 to 0.05 μm ( 20-50 nm). If the shell thickness is too large, the fixing property is lowered. When the core particle diameter and the shell thickness of the polymerized toner can be observed with an electron microscope, they can be obtained by directly measuring the size and shell thickness of particles randomly selected from the observation photograph. If it is difficult to distinguish and observe the core particle and the shell with an electron microscope, calculate the thickness of the shell from the volume average particle diameter of the core particle and the amount of polymerizable monomer used to form the shell. Can do.

  In the case of a polymerized toner, the core-shell structure is formed by using the colored resin particles as core particles, polymerizing a shell polymerizable monomer in the presence of the core particles, and forming a polymer layer on the surface of the core particles. A method of forming (shell) (in situ polymerization method) is preferred.

  The toner for developing an electrostatic charge image of the present invention has a low fixing temperature, excellent continuous printing characteristics after storage at a high temperature, and does not whiten the developing roll. The toner for developing an electrostatic charge image of the present invention preferably has a degree of aggregation after storage at 62.5 ° C. for 6 hours, preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 2% by weight or less. Excellent blocking resistance.

  When the electrostatic image developing toner of the present invention is used as a non-magnetic one-component developer, it is preferable to mix an external additive with toner particles (colored resin particles). Examples of the external additive include inorganic particles and organic resin particles that act as a fluidizing agent and an abrasive. Examples of the inorganic particles include silicon dioxide (silica), aluminum oxide (alumina), titanium oxide, zinc oxide, tin oxide, barium titanate, and strontium titanate. As organic resin particles, methacrylic acid ester polymer particles, acrylic acid ester polymer particles, styrene-methacrylic acid ester copolymer particles, styrene-acrylic acid ester copolymer particles, a core is a methacrylic acid ester copolymer, and a shell And core-shell type particles formed of a styrene polymer.

  Among these, inorganic oxide particles are preferable, and silicon dioxide is particularly preferable. The surface of the inorganic fine particles can be hydrophobized, and silicon dioxide particles that have been hydrophobized are particularly suitable. Two or more types of external additives may be used in combination. In the case of using a combination of external additives, a method of combining inorganic particles having different average particle sizes or a combination of inorganic particles and organic resin particles is preferable. . The amount of the external additive is not particularly limited, but is usually 0.1 to 6 parts by weight with respect to 100 parts by weight of the toner particles. In order to attach the external additive to the toner particles, the toner particles and the external additive are usually placed in a mixer such as a Henschel mixer and stirred.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Parts and% are based on weight unless otherwise specified. Physical properties and characteristics were evaluated by the following methods.

(1) Amount dissolved (g / 100 g ST; 35 ° C.):
The amount of fatty acid ester compound dissolved in styrene was determined by measuring the amount of fatty acid ester compound dissolved in 100 g of styrene held at 35 ° C.

(2) Hydroxyl value (mgKOH / g):
The hydroxyl value of the fatty acid ester compound was measured as the number of mg of potassium hydroxide required to neutralize acetic acid necessary for acetylating the free hydroxyl group contained in 1 g of the sample.

  Specifically, as an acetylating reagent, 25 g of acetic anhydride was placed in a 100-mL volumetric flask and pyridine (JIS K 8777) was added up to the marked line and mixed. 2 g of a sample is weighed into a 150 mL neck round bottom flask and 5 mL of acetylating reagent is added. Place a small funnel on the neck of the long neck round bottom flask, submerge the bottom of the flask in a heating bath to a depth of about 1 cm and heat to 95-100 ° C. To prevent the temperature of the neck of the flask from rising due to the heat of the bath at this time, a cardboard disk with a round hole in it is put on the base of the neck of the flask. After 1 hour, the long round bottom flask is removed from the bath and cooled, and 1 mL of water is added from the funnel. Shaking the mixture generates heat and turns the anhydride into acid. To ensure the reaction is complete, the flask is once more placed in a heating bath and heated for 10 minutes. Cool to room temperature again, and rinse the condensed liquid on the neck of the funnel or flask into the flask with 5 mL of neutral ethanol. The contents in the flask are titrated with a 0.5 mol / L potassium hydroxide-ethanol standard solution using a phenolphthalein indicator (or alkali blue 6B indicator when the mixture is strong brown). A blank test is performed in parallel with this test. The acid value of the sample is determined separately.

Hydroxyl value = [[(A−B) × 28.05 × F] / C] + acid value A: 0.5 mol / L potassium hydroxide-ethanol standard solution usage (mL) in blank test,
B: 0.5 mol / L potassium hydroxide-ethanol standard solution usage (mL) in this test,
F: Factor of 0.5 mol / L potassium hydroxide-ethanol standard solution,
C: Sampling amount (g).

(3) Maximum endothermic peak temperature (° C):
The maximum endothermic peak temperature of the fatty acid ester compound was measured according to ASTM D3418-82. More specifically, using a differential scanning calorimeter, the sample was heated at a heating rate of 10 ° C./min, and the temperature showing the maximum endothermic peak of the DSC curve obtained in the process was measured. As a differential scanning calorimeter, “SSC5200” manufactured by Seiko Denshi Kogyo Co., Ltd. was used.

(4) The ratio of the number of functional groups of the fatty acid ester compound and the ratio of the number of carbon atoms of the fatty acid residue:
A 2 g sample was weighed, 6N hydrochloric acid was added to the sample, and the mixture was heated at 110 ° C. for 6 hours for hydrolysis. After hydrolysis, the sample solution was transferred to a separatory funnel and extracted by adding diethyl ether. About the ether phase, it used for GC-MS measurement as it was. For the aqueous phase, water was evaporated to dryness, and then 1 ml of pyridine, 0.2 ml of hexamethyldisilazane and 0.1 ml of trimethylchlorosilane were added and heated at 100 ° C. for 20 minutes for silylation. GC-MS (gas chromatography / mass spectrometry) measurement was performed on the sample subjected to the silylation. The proportion of each component was determined from the peak area value on the chromatogram.

Measuring device: Agilent 5975 inert GC / MS system (manufactured by Agilent),
Column: HP-5 ms (30 m × 250 μmφ × 0.25 μm),
Column temperature: temperature raised from 100 ° C. to 320 ° C. (temperature raising rate 10 ° C./min, held for 15 minutes),
Carrier gas: He (1 ml / min),
Ionization method: EI (70 eV).

(5) Volume average particle size (Dv) and particle size distribution (Dv / Dp):
The volume average particle size (Dv) of the colored resin particles (including the core-shell type) and the particle size distribution represented by the ratio (Dv / Dp) of the volume average particle size (Dv) to the number average particle size (Dp) are , Measured by Multisizer (manufactured by Coulter). The measurement with a multisizer was performed under the conditions of an aperture diameter = 100 μm, medium = Isoton II, concentration = 10%, and number of measured particles = 50000.

(6) Average circularity:
The average circularity of the colored resin particles is a value obtained by measurement with a water dispersion system using a flow particle image analyzer (FPIA-1000; manufactured by Toa Medical Electronics). As a measurement method, 10 ml of ion-exchanged water is prepared in advance in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then 0.02 g of a measurement sample is added and dispersed uniformly. . As a dispersion means, an ultrasonic dispersion machine was used, and dispersion treatment was performed under conditions of 60 W and 3 minutes. The density | concentration of the colored resin particle at the time of a measurement was adjusted so that it might become 3000-10000 piece / microliter. The circularity of 1000 to 10,000 colored resin particles was measured. Using this data, the average circularity was determined.

(7) Shell thickness:
Since the thickness of the shell was thin and could not be confirmed by microscopic observation, the shell thickness was calculated using the following formula.

x = r (1 + s / 100ρ) ^1/3 −r
r: radius of volume average particle diameter of core particles before addition of monomer for shell,
x: shell thickness (μm),
s: Number of added shell monomer to 100 parts by weight of core monomer,
ρ: density of shell polymer (g / cm ³ ) = 1.0 g / cm ³

(8) Fixing temperature (° C):
A fixing test was performed using a printer modified so that the temperature of the fixing roll portion of a commercially available non-magnetic one-component developing type printer (printing speed = 22 sheets / min) could be changed. The fixing test was performed by changing the temperature of the fixing roll of the modified printer, measuring the fixing rate of the developer at each temperature, and determining the relationship between the temperature and the fixing rate. The fixing rate is determined based on the ratio of the image density before and after the tape peeling operation on the black solid area of the test paper printed with the modified printer, after being left for 5 minutes or more to stabilize the temperature of the fixing roll when the temperature is changed. Calculated. That is, assuming that the image density before tape peeling is before ID and the image density after tape peeling is after ID, the fixing rate can be calculated from the following equation.
Fixing rate (%) = (after ID / before ID) × 100

  The tape peeling operation means that an adhesive tape (Scotch Mending Tape 810-3-18 manufactured by Sumitomo 3M Co., Ltd.) is applied to the measurement part of the test paper, pressed and attached with a constant pressure, and then the paper is moved along the paper at a constant speed. It is a series of operations to peel the adhesive tape in the direction. The image density was measured using a reflection type image density measuring machine manufactured by Macbeth. In this fixing test, the fixing roll temperature corresponding to a fixing rate of 80% was used as the fixing temperature of the developer.

(9) Cover:
Copy paper is set in a commercially available non-magnetic one-component development type printer (22 sheets), toner for developing an electrostatic image is put in the developing device, and the temperature is 23 ° C. and the humidity is 50% (N / N environment) )), And continuously printing at 5% printing density. When printing 100 sheets, white solid printing is performed. The toner on the developed photoconductor is adhesive tape (Scotch Mending Tape 810, manufactured by Sumitomo 3M Limited). -3-18). The adhesive tape was affixed on a new printing paper, and the whiteness (B) was measured with a whiteness meter (manufactured by Nippon Denshoku). At the same time, only the adhesive tape was attached to the printing paper, and the whiteness (A) was measured. The difference in whiteness (A−B) was defined as a fog value (%). Smaller values indicate less fogging.

  Further, the electrostatic charge image developing toner was sealed in a sealable container in an environment of a temperature of 23 ° C. and a humidity of 50%. The container was stored in an environment at a temperature of 50 ° C. for 5 days, then opened and returned to an N / N environment at a temperature of 23 ° C. and a humidity of 50%. The toner for developing an electrostatic image was taken out from the container, and the fog value was measured in the same manner as described above using the toner for developing an electrostatic image. This was defined as the fog value after high temperature storage.

(10) Durability:
The toner for developing an electrostatic charge image is put in the developing device of the printer used above, and it is left overnight in an N / N environment at a temperature of 23 ° C. and a humidity of 50%. White solid printing was performed every time. The fog value was measured in the same manner as described above, and the number of continuous prints that could maintain this value at 1.0% or less was examined up to 15,000. The durability of the toner for developing an electrostatic charge image was evaluated by the number of continuously printed sheets capable of maintaining a fog value of 1.0% or less.

  Further, the electrostatic charge image developing toner was sealed in an N / N environment having a temperature of 23 ° C. and a humidity of 50% in a sealable container. The container was stored in an environment at a temperature of 50 ° C. for 5 days, then opened and returned to an N / N environment at a temperature of 23 ° C. and a humidity of 50%. The electrostatic image developing toner was taken out from the container, and the durability was examined in the same manner as described above using the electrostatic image developing toner. The durability after high temperature storage was evaluated by the number of continuous prints that can maintain the fog value of 1.0% or less.

(11) Whitening of developing roll:
In the durability evaluation after leaving at high temperature, the developing roll when the fog value exceeds 1.0% and the developing roll before the evaluation are visually compared, and the white color is whitened. Yes.

(12) Blocking resistance:
After weighing 20 g of the electrostatic charge image developing toner in a plastic container having an internal volume of 100 ml, the mouth of the container was sealed and immersed in a constant temperature water bath at 62.5 ° C. for 8 hours. The contents of the container were sieved by vibrating with a sieve having an opening of 150 μm and an amplitude of 1.0 mm for 30 seconds. At this time, the weight of the toner remaining on the sieve was measured, and the blocking resistance was evaluated by the ratio (%) of the weight to 20 g.

[Example 1]
1. Preparation of polymerizable monomer composition for core:
Polymeric monomer for core consisting of 75 parts of styrene and 25 parts of n-butyl acrylate, 0.25 part of polymethacrylic acid ester macromonomer (product name AA6, manufactured by Toagosei Co., Ltd.) as a macromonomer, copper phthalocyanine pigment ( Dai Nippon Ink Co., Ltd., product name CTBX121) 1 part, and positive charge control resin (quaternary ammonium base-containing styrene / acrylic resin, Fujikura Kasei Co., Ltd. product name FCA-161P) 0.8 part, stirring blade After stirring and mixing with a stirring device, the mixture was uniformly dispersed by a media type disperser.

  To this mixed solution, 5 parts of a polyglycerol behenate ester compound (fatty acid ester compound A) was added, mixed and dissolved to obtain a core polymerizable monomer composition. The polyglycerin behenate ester compound was prepared by placing 100 g of polyglycerin # 500 (Sakamoto Yakuhin Kogyo Co., Ltd.) and 490 g of behenic acid in a reaction vessel and reacting them at 240 ° C. under a catalyst and a nitrogen stream, and the esterification rate was 95% or more. It was prepared by reacting so that. The maximum thermal peak temperature of this fatty acid ester compound was 71 ° C. Table 1 shows the results of analysis of the number of functional groups and carbon number of saturated fatty acid residues.

2. Preparation of aqueous dispersion medium:
While stirring an aqueous solution in which 8.6 parts of magnesium chloride (water-soluble polyvalent metal salt) is dissolved in 250 parts of ion-exchanged water at 25 ° C., sodium hydroxide (alkali metal hydroxide) is added to 50 parts of ion-exchanged water while stirring. An aqueous solution in which 4.8 parts were dissolved was gradually added to prepare a dispersion of magnesium hydroxide colloid (slightly water-soluble metal hydroxide colloid). When the particle size distribution of the obtained colloid was measured with a particle size distribution measuring device (product name: SALD tangible distribution measuring device manufactured by Shimadzu Corporation), D ₅₀ (50% cumulative value from the small particle size of the number particle size distribution) 0.36 μm and D ₉₀ (90% cumulative value) was 0.80 μm.

3. Granulation process:
The core polymerizable monomer composition was added to the magnesium hydroxide colloid dispersion at 25 ° C., and the mixture was stirred with a stirring device equipped with a stirring blade until the resulting coarse droplets were stabilized. Here, 4.5 parts of t-butylperoxydiethyl acetate as a polymerization initiator, 1.0 part of tetraethylthiuram disulfide (TETD) as a molecular weight regulator, and 0.5 part of divinylbenzene as a crosslinkable polymerizable monomer Then, using a high-speed shearing stirrer (product name Ebara Milder, manufactured by Ebara Seisakusho), high-speed shearing stirring is performed at a rotational speed of 15,000 rpm for 10 minutes to form droplets of the polymerizable monomer composition. Grained.

4). Preparation of colloidal dispersion for pre-charging:
While stirring an aqueous solution in which 1.51 parts of magnesium chloride was dissolved in 39.64 parts of ion-exchanged water at 25 ° C., an aqueous solution in which 0.92 parts of sodium hydroxide was dissolved in 7.93 parts of ion-exchanged water was gradually added. To prepare a dispersion of a preliminarily charged magnesium hydroxide colloid.

5. Preparation of polymerizable monomer for shell:
A solution obtained by dissolving 1 part of methyl methacrylate as a polymerizable monomer for shell and 0.1 part of product name VA086 manufactured by Wako Pure Chemical Industries, Ltd. as a water-soluble polymerization initiator for shell in 10 parts of ion-exchanged water. Prepared.

6). Suspension polymerization process:
A reactor equipped with a stirring device having a stirring blade was prepared. From the upper part of the reactor, the preliminarily charged magnesium hydroxide colloid dispersion was sprayed on the reactor wall and the stirrer through a sprayer. The preliminarily charged dispersion of colloidal magnesium hydroxide was collected at the bottom of the reactor.

  From the upper part of the reactor, an aqueous dispersion in which droplets of the polymerizable monomer monopolymer for the core were dispersed was added. At this time, the preliminarily charged dispersion of magnesium hydroxide colloid accumulated in the lower part of the reactor moderated the impact of the dropping of the aqueous dispersion in which the droplets of the polymerizable monomer for the core were dispersed.

  The dispersion in the reactor was heated with a jacket provided outside the reactor until the liquid temperature reached 90 ° C., thereby starting the polymerization reaction of the core polymerizable monomer composition. When the polymerization reaction was continued and the polymerization conversion rate reached 95%, the shell polymerizable monomer and the shell water-soluble polymerization initiator were added while maintaining the temperature in the reaction system at 90 ° C. . Continue the polymerization reaction by maintaining the temperature in the reaction system at 90 ° C for 3 hours, and then stop the polymerization reaction by lowering the temperature in the system to about 25 ° C by circulating cooling water through the jacket. did. Through the above operation, an aqueous dispersion containing the produced core-shell type colored polymer particles was obtained in the reactor. The pH of the internal solution in the reactor was 0.5.

7). Post-processing process:
The aqueous dispersion containing the obtained colored polymer particles was stripped. First, ion-exchanged water was added to the aqueous dispersion containing the colored polymer particles and diluted so that the solid content concentration was 20%. The aqueous dispersion containing the colored polymer particles after dilution was supplied to the evaporator. To this aqueous dispersion, 1 part of a non-silicone antifoaming agent (manufactured by San Nopco, product name SN deformer 180) was added. Nitrogen gas was allowed to flow into the evaporator, and the gas layer was replaced with nitrogen gas. Next, the aqueous dispersion liquid containing the colored polymer particles is stirred with a stirring blade at a rotation speed of 20 rpm, and warm water is passed through a jacket provided in contact with the outside of the evaporator to warm the evaporator, The aqueous dispersion containing the colored polymer particles was heated to 80 ° C. After that, the blower is started and nitrogen gas is blown into the liquid of the aqueous dispersion containing the colored polymer particles from the gas blow pipe having a straight pipe shape to remove volatile substances in the liquid. It was. Such a stripping step was performed for 6 hours while adjusting the liquid temperature in the evaporator at 80 ° C., the pressure of 48 kPa, and the flow rate of nitrogen gas of 0.1 liter / hr · kg. During this time, the foam level was maintained at 90% or more and 95% or less. Thereafter, the aqueous medium containing the colored polymer particles was cooled to 25 ° C. by passing cooling water through the jacket.

  While stirring the aqueous medium containing the colored polymer particles after cooling, acid washing was performed by adding sulfuric acid to neutralize the pH of the liquid to 4.5. The wet colored polymer particles were separated from the aqueous dispersion containing the neutralized colored polymer particles by filtration. Thereafter, 500 parts of ion-exchanged water was newly added, and the colored polymer particles in a wet state were slurried again and again filtered. By repeating this slurrying and filtering five times, the wet colored polymer particles were washed with water.

  The wet colored polymer particles after washing with water were dried with a vacuum dryer at a temperature of 50 ° C. and a pressure of 4 kPa for 24 hours to obtain dried colored polymer particles. The obtained colored polymer particles are core-shell type colored polymer particles, the volume average particle diameter (Dv) is 7.4 μm, the particle size distribution (Dv / Dp) is 1.21, the shell thickness is 30 nm, The average circularity was 0.990.

8). Non-magnetic one-component developer:
To 100 parts of colored polymer particles, 0.8 part of hydrophobized fine particles (product name: TG820F, manufactured by Capot Co., Ltd.) and 1 part of hydrophobized fine particles (product name: NA50Y, manufactured by Nippon Aerosil Co., Ltd.) are added. The mixture was mixed using a mixer to obtain a non-magnetic one-component developer. Table 2 summarizes the test results of the obtained developer (sometimes simply referred to as toner).

[Examples 2 and 3]
Core-shell colored polymer particles and a non-magnetic one-component developer were produced in the same manner as in Example 1 except that the addition amounts of the positive charge control resin and the fatty acid ester compound A were changed as shown in Table 2. The results are shown in Table 2.

[Comparative Example 1]
The fatty acid ester compound A is added to the following fatty acid ester compound B, the addition amount of the positive charge control resin is changed from 0.8 part to 0.7 part, and the use amount of the polymerizable monomer for shell is changed from 4.2 part to 2.1 parts. The core-shell type colored polymer particles and the non-magnetic one-component developer were produced in the same manner as in Example 1 except that each part was changed. The results are shown in Table 3.

  The fatty acid ester compound B was synthesized by the same method as the fatty acid ester compound A described in Example 1, except that 100 g of polyglycerin # 500 (manufactured by Sakamoto Pharmaceutical Co., Ltd.) and 410 g of stearic acid (18 carbon atoms) were used. did.

[Comparative Example 2]
Copper phthalocyanine pigment in carbon black “# 25” (Mitsubishi Chemical Co.), 0.8 parts of positive charge control resin “FCA-161P” in 1 part of charge control agent “Spiron Black TRH” (Hodogaya Chemical Co., Ltd.) The core-shell type colored polymer particles and the non-magnetic one-component development are the same as in Example 1 except that the fatty acid ester compound A is changed to the following fatty acid ester compound C and the shell layer is not formed. An agent was produced. The results are shown in Table 3.

  Fatty acid ester compound C is the same as in Example 1 except that 100 g of polyglycerin # 500 (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) and 205 g of stearic acid (18 carbon atoms) and 245 g of behenic acid (22 carbon atoms) are used as fatty acids. The compound was synthesized in the same manner as described for the fatty acid ester compound A.

[Comparative Example 3]
Copper phthalocyanine pigment is carbon black “# 25B” (manufactured by Mitsubishi Chemical), 0.8 part of positive charge control resin “FCA-161P” is positive charge control resin “FCA-207P” (a quaternary ammonium base-containing styrene / acrylic) Resin, manufactured by Fujikura Kasei Co., Ltd.), except that the fatty acid ester compound A was changed to the following fatty acid ester compound D and the amount of the polymerizable monomer for shell was changed from 4.2 parts to 1 part. Produced core-shell colored polymer particles and a non-magnetic one-component developer in the same manner as in Example 1. The fatty acid ester compound D is a myristic acid ester of dipentaerythritol. The analytical values of the fatty acid ester compound are shown in Table 1, and the measurement results of the toner characteristics are shown in Table 3.

[Comparative Example 4]
0.8 parts of the positive charge control resin “FCA-161P” is added to 0.5 parts of the positive charge control resin “FCA-207P” (a quaternary ammonium base-containing styrene / acrylic resin, manufactured by Fujikura Kasei Co., Ltd.). In the same manner as in Example 1, except that the amount of the polymerizable monomer for shell used in the fatty acid ester compound E was changed from 4.2 parts to 3 parts, the core-shell type colored polymer particles and the nonmagnetic material were changed. A one-component developer was produced. The results are shown in Table 3.

  For fatty acid ester compound E, 100 g of polyglycerin # 310 (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) and 490 g of behenic acid are put in a reaction vessel and reacted at 240 ° C. in a catalyst and nitrogen stream so that the esterification rate becomes 95% or more. It was prepared by reacting. Table 1 shows the results of analysis of the number of functional groups and carbon number of saturated fatty acid residues.

  As is clear from the comparison of the results in Table 2 and Table 3, the fatty acid ester compound has a saturated fatty acid residue in which the proportion of carbon atoms of 20 to 25 is 90% or more and has a specific number of functional group distributions. By using an ester, a toner for developing an electrostatic charge image is obtained that has low temperature fixability, excellent continuous printing characteristics after long-term storage in a high-temperature atmosphere, no whitening of the developing roll, and extremely low aggregation after storage at high temperatures. (Examples 1 to 3 in Table 2).

  On the other hand, even if it is a fatty acid ester compound of polyglycerin, when a fatty acid ester compound having 18 carbon atoms is used, the continuous printing characteristics after long-term storage in a high-temperature atmosphere tend to decrease. Thus, the developing roll is whitened, and a toner for developing an electrostatic image having a high degree of aggregation after storage at a high temperature is obtained (Comparative Example 1 in Table 3).

  Even if it is a polyglycerin fatty acid ester compound, when an ester compound using 18 and 22 fatty acids in equimolar amounts is used, the continuous printing characteristics after long-term storage in a high-temperature atmosphere are reduced. Thus, the developing roll is whitened and the toner for developing an electrostatic charge image has a remarkably large degree of aggregation after storage at a high temperature (Comparative Example 2 in Table 3).

  When dipentaerythritol myristic acid ester is used, the continuous printing characteristics after long-term storage in a high-temperature atmosphere are reduced, the developing roll is whitened, and the anti-blocking property after storage at high temperatures tends to decrease. A toner for developing a charge image is obtained (Comparative Example 3 in Table 3).

  Even when polyglycolic acid behenic acid ester is used as the fatty acid ester compound, if the requirement for the number of functional groups specified in the present invention is not satisfied, the continuous printing characteristics after long-term storage in a high-temperature atmosphere are reduced. A toner for developing an electrostatic image having a tendency, whitening of the developing roll, and a high degree of aggregation after storage at a high temperature is obtained (Comparative Example 4 in Table 3).

  The electrostatic image developing toner of the present invention is used as a developer for developing an electrostatic latent image formed on a photoreceptor in an electrophotographic (including electrostatic printing) image forming apparatus. Can do.

Claims (8)

In the electrostatic image developing toner containing a binder resin, a colorant, a charge control agent, and a fatty acid ester compound, the fatty acid ester compound is
(A) a fatty acid ester compound of a polyhydric alcohol mixture containing at least tetrafunctional to octafunctional polyhydric alcohol and a fatty acid,
(B) The content of the tetrafunctional or lower fatty acid ester compound is 10% by weight or less,
(C) The content ratio of the fatty acid ester compound having 8 or more functional groups is 15% by weight or more,
(D) 90% or more of the fatty acid residues have 20 to 25 carbon atoms, and
(E) An electrostatic charge image developing toner having a hydroxyl value of 8.0 mgKOH / g or less.   2. The electrostatic image developing toner according to claim 1, wherein the fatty acid ester compound contains 5 to 7 functional fatty acid ester compounds at a ratio of 15% by weight or more.   The electrostatic image developing toner according to claim 1, wherein the polyhydric alcohol mixture is a polyglycerin containing a glycerin polycondensate mixture of at least a dimer to a hexamer.   The electrostatic image developing toner according to claim 3, wherein the fatty acid ester compound is a fatty acid ester compound of the polyglycerin and a saturated fatty acid having 20 to 25 carbon atoms.   Colored resin particles containing a binder resin, a colorant, a charge control agent, and a fatty acid ester compound, or core-shell type colored resin particles in which a shell made of a polymer layer is further formed on the surface of the colored resin particles. The toner for developing an electrostatic charge image according to any one of claims 1 to 4.   The electrostatic charge image developing toner according to claim 1, wherein the charge control agent is a charge control resin.   The volume average particle diameter (Dv) is 6 to 10 μm, the ratio of the volume average particle diameter to the number average particle diameter (Dp) (Dv / Dp) is 1 to 1.3, and the average circularity is 0.960 to 0 The toner for developing an electrostatic charge image according to claim 1, which is .995.   The toner for developing an electrostatic charge image according to any one of claims 1 to 7, which has a degree of aggregation after storage at 62.5 ° C for 6 hours of 10% by weight or less.