JP2012198569A - Toner for electrostatic charge image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide toner for electrostatic charge image development, being excellent in low-temperature fixability, storage stability and printing durability.SOLUTION: The toner for electrostatic charge image development comprises colored resin particles containing binder resin, colorant and ester wax; and an external additive. The ester wax contains: a polyfunctional fatty acid ester compound of polyglycerol being quadrivalent or higher polyhydric alcohol and 14-25C saturated or unsaturated fatty acid; and a monofunctional fatty acid ester compound of 13-25C higher saturated aliphatic monohydric alcohol and 14-25C saturated or unsaturated fatty acid; in a weight ratio ranging from 50:50 to 95:5.

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 an ester wax which acts as a release agent, and has an excellent electrostatic charge with excellent fixability (low-temperature fixability), storage stability (blocking resistance), and print durability (continuous print characteristics). The present invention relates to an image developing toner.

  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. These image forming apparatuses are strongly required to be lightweight, downsized, and highly functional. Integration of image forming apparatuses and other devices such as facsimiles is in progress, and compactness 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, in addition to the low-temperature fixability, the electrostatic image developing toner is required to have excellent printing durability and blocking resistance even when placed in a high-temperature atmosphere for a long time.

  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, when the toner composition is designed so as to lower the fixing temperature, the electrostatic image developing toner tends to aggregate and the anti-blocking property decreases.

  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 tends to aggregate during storage, and in addition, the image quality is lowered and the printing durability in continuous printing is lowered.

  Conventionally, an ester wax such as a fatty acid ester compound of a polyhydric alcohol is included in the toner in order to obtain a toner for developing an electrostatic image that has an excellent balance between low-temperature fixability and blocking resistance and is capable of high-quality printing. Various methods have been proposed.

  JP-A-4-194948 (Patent Document 1) discloses a resin composition for toner in which a polyglycerol partial ester compound is blended with a styrene- (meth) acrylate copolymer. However, since the polyglycerin partial ester has a large amount of OH groups remaining without being esterified, the chargeability of the toner under high temperature and high humidity becomes unstable, making it difficult to obtain a sufficient image density. Cheap. A polymerizable monomer composition containing a polyglycerin partial ester produces droplets with a sharp particle size distribution due to the influence of OH groups remaining in the polyglycerin partial ester in the droplet formation step in an aqueous medium. It becomes difficult to form, and as a result, a polymerized toner having a sharp particle size distribution cannot be produced.

  Japanese Patent Application Laid-Open No. 2001-147550 (Patent Document 2) describes a toner for developing electrostatic images containing a binder resin, a colorant, and a polyfunctional ester compound, which has 5 or more ester bonds in the molecule. In addition, a toner for developing an electrostatic charge image using a polyfunctional ester having a molecular weight of 2000 or more, a dissolution amount with respect to 100 g of styrene measured at 35 ° C. of 5 g or more, 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, the electrostatic charge image developing toner containing these polyfunctional ester compounds has a strong tendency to aggregate when placed in a high temperature atmosphere for a long time.

  In JP 2001-272813 (Patent Document 3), each functional group of a trihydric or higher polyhydric alcohol reacts with a carboxylic acid having 10 to 30 carbon atoms to form an ester bond. In addition, a toner release agent comprising a polyfunctional ester compound is disclosed. However, the toner for developing an electrostatic charge image containing the polyfunctional ester compound is not sufficient in storage stability (blocking resistance) and printing durability.

  Japanese Patent Application Laid-Open No. 2003-241418 (Patent Document 4) 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 toner for developing an electrostatic charge image containing the polyglycerin fatty acid ester of the fatty acid is inferior in printing durability after being left in a high-temperature atmosphere and is not sufficient in blocking resistance.

  Japanese Patent Application Laid-Open No. 2006-98745 (Patent Document 5) 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 5, dipentaerythritol hexamyristate and pentaerythritol tetrastearate are used as the ester. However, the electrostatic image developing toner containing these fatty acid ester compounds does not have sufficient printing durability after being left in a high temperature atmosphere, and further improvements are required.

JP-A-4-194948 JP 2001-147550 A Japanese Patent Laid-Open No. 2001-272813 JP 2003-241418 A JP 2006-98745 A

  An object of the present invention is to provide a toner for developing an electrostatic image having excellent fixability (low temperature fixability), storage stability (blocking resistance), and printing durability (continuous printing characteristics).

  The inventors of the present invention have a problem that the toner characteristics of an electrostatic charge image developing toner containing a polyfunctional ester compound of a polyhydric alcohol and a carboxylic acid compound vary greatly depending on the type of the polyfunctional ester compound. Focused on the point.

  For example, when a polyglycerol fatty acid ester is used as the polyfunctional ester compound, an electrostatic charge image developing toner excellent in storage stability and printing durability can be obtained, but it is difficult to sufficiently reduce the fixing temperature. It is. When, for example, pentaerythritol tetrastearate is used as the polyfunctional ester compound, a toner for developing an electrostatic image having excellent low-temperature fixability can be obtained, but its storage stability and printing durability are insufficient.

  On the other hand, when a monofunctional ester compound of a monohydric alcohol and a carboxylic acid compound is used as the ester wax, a toner for developing an electrostatic image having excellent storage stability and printing durability can be obtained, but the fixing temperature can be lowered. Can not.

  Therefore, as a result of diligent research to solve the above problems, the present inventors used a combination of a polyfunctional ester compound and a monofunctional ester compound, which were each capable of exhibiting insufficient toner characteristics, in a specific ratio. As a result, it has been found that an electrostatic charge image developing toner excellent in low temperature fixability, storage stability and printing durability can be obtained. The present invention has been completed based on these findings.

  According to the present invention, in an electrostatic charge image developing toner containing colored resin particles containing a binder resin, a colorant, and an ester wax, and an external additive, the ester wax has a polyvalent value of 4 or more. Polyfunctional fatty acid ester compound of polyglycerol of alcohol, saturated or unsaturated fatty acid having 14 to 25 carbon atoms, higher saturated aliphatic monohydric alcohol having 13 to 25 carbon atoms, and saturated having 14 to 25 carbon atoms Alternatively, a toner for developing an electrostatic image is provided, which contains a monofunctional fatty acid ester compound with an unsaturated fatty acid at a weight ratio in the range of 50:50 to 95: 5.

  According to the present invention, it is possible to provide an electrostatic charge image developing toner having a sufficiently low minimum fixing temperature, a high level of storage stability and printing durability, and a high balance of these characteristics.

  The toner for developing an electrostatic charge image of the present invention can sufficiently meet the demands for higher printing speed, lower fixing temperature, full color, and the like. The toner for developing an electrostatic charge image of the present invention can cope with the reduction in weight, size, and enhancement of functionality of an electrophotographic image forming apparatus.

1. Ester wax:
As the ester wax, a polyfunctional ester compound A of a polyhydric alcohol having a valence of 4 or more and a carboxylic acid compound and a monofunctional ester compound B of a monohydric alcohol and a carboxylic acid compound are mixed at a weight ratio of A: B of 50:50. Used in combination within the range of ~ 95: 5. The weight ratio of A: B is preferably 55:45 to 90:10, more preferably 60:40 to 85:15, and particularly preferably 65:35 to 80:20.

  If the weight ratio of the polyfunctional ester compound is too small, the fixing temperature of the electrostatic image developing toner cannot be lowered sufficiently. If the weight ratio of the polyfunctional ester compound is too large, depending on the type of the polyfunctional ester compound, the effect of lowering the fixing temperature is reduced, and the storage stability and printing durability are lowered. By using a polyfunctional ester compound and a monofunctional ester compound in a weight ratio within the above range, a toner for developing an electrostatic image having a high balance of low-temperature fixability, storage stability, and printing durability can be obtained. .

  The polyfunctional ester compound means an ester compound having a plurality of ester bonds in the molecule depending on the valence of the polyhydric alcohol used. A monofunctional ester compound means a monoester compound of a monohydric alcohol and a carboxylic acid compound.

  Both the polyfunctional ester compound and the monofunctional ester compound used are substantially complete ester compounds and are not partially esterified products. The hydroxyl value of the polyfunctional ester compound and monofunctional ester compound used is preferably 8.0 mgKOH / g or less, more preferably 5.0 mgKOH / g or less, particularly preferably 3.0 mgKOH / g or less. The value is preferably 5.0 mgKOH / g or less, more preferably 3.0 mgKOH / g or less, still more preferably 1.0 mgKOH / g or less, and particularly preferably 0.5 mgKOH / g or less.

  When the hydroxyl value of the polyfunctional ester compound and the monofunctional ester compound is too high, when producing a polymerized toner, when droplets of a monomer composition containing these ester compounds are granulated in an aqueous dispersion medium. It adversely affects and makes it difficult to granulate droplet particles having a uniform particle size distribution and stability. A toner for developing an electrostatic charge image containing an ester compound having a high hydroxyl value may be deteriorated in chargeability under high temperature and high humidity and fogging may occur.

  The polyfunctional ester compound is preferably a polyfunctional fatty acid ester of a tetrahydric or higher polyhydric alcohol and a fatty acid. The tetrahydric or higher polyhydric alcohol may be a single compound or a polyhydric alcohol mixture. When the polyhydric alcohol having 4 or more valences is a polyhydric alcohol mixture, the polyfunctional ester compound is a polyfunctional fatty acid ester mixture of a polyhydric alcohol mixture containing at least each of 4 to 8 polyhydric alcohols and a fatty acid. It is preferable that

  Examples of tetrahydric or higher polyhydric alcohols include diglycerin, triglycerin, tetraglycerin, pentaglycerin, hexaglycerin, heptaglycerin, octaglycerin, nonaglycerin, decaglycerin, pentadecaglycerin, eicosaglycerin, and triacontag glycerin. Dehydrated condensate of glycerin (polycondensate) (hereinafter sometimes referred to as “polyglycerin”); aliphatic polyhydric alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol; D-erythrose, arabinose, D-xylulose , Α-D-xylose, 2-deoxy-D-ribose, α-D-lyxose, D-ribulose, D-arabitol, ribitol, β-D-altrose, β-D-allose, α-D-galactose, β-D-Ga Fructose, α-L-galactose, α-D-quinobose, α-D-glucose, β-D-glucose, L-sorbose, D-tagatose, α-D-talose, D-fucose, α-D-fucose, α-L-fucose, D-psicose, D-fructose, D-mannose, α-D-mannose, α-L-rhamnose, D-inositol, myo-inositol, galactitol, D-glycitol, D-mannitol, D -Altro-heptulose, D-manno-heptulose, D-altro-3-heptulose, D-glycero-D-galacto-heptylol, D-galacto-D-galacto-octitol, D-glycero-D-manno-octulose, D-erythro-L-gulo-nonuro , Carbohydrates such as agarobiose, α-gentiorose, sucrose, β-cellobiose, β-maltose, α-lactose, raffinose, α-cyclodextrin, β-cyclodextrin, and dehydration condensates thereof. .

  Among these, glycerin polycondensates (polyglycerin); aliphatic polyhydric alcohols such as pentaerythritol, dipentaerythritol, and tripentaerythritol are preferable. In the present invention, polyglycerin of a polyhydric alcohol having a valence of 4 or more is used.

  The molecular weight of the polyhydric alcohol is preferably 100 to 1,500, more preferably 110 to 1,000, and particularly preferably 150 to 800. Therefore, when a polyhydric alcohol mixture is used as the polyhydric alcohol, the average molecular weight of the polyhydric alcohol mixture is also within the above range. A polyfunctional ester compound using a polyhydric alcohol having a too high molecular weight tends to have a small release effect.

  From the viewpoint of highly balancing the low-temperature fixability, storage stability, and printing durability of the electrostatic image developing toner, glycerin polycondensate (polyglycerin) is particularly preferred as the polyhydric alcohol. Polyglycerin is generally obtained as a glycerin polycondensate mixture (polyhydric alcohol mixture) having a different degree of polycondensation. Glycerin and polyglycerin can be represented by the following formula.

  In the formula, n is an integer of 1 or more. 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 hydroxyl groups thereof is four. As n increases by one, the number of hydroxyl groups increases by one. That is, the number of hydroxyl groups = 3 + (n−1). In the case of n = 6, it is a glycerin hexamer and the number of hydroxyl groups thereof is 8.

  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 is a polyhydric alcohol mixture containing at least each of polyhydric alcohols from tetravalent to octavalent. This polyglycerin may contain a glycerin monomer and / or a polyglycerin of 7-mer or more.

  The polyfunctional ester compound finally obtained as polyglycerin has a content ratio of tetrafunctional or lower ester compounds of 10% by weight or less, and a content ratio of 8-functional or higher functional ester compounds is 15% by weight or higher. It is preferable to use polyglycerin having such a functional group distribution. The polyglycerin preferably has a functional group distribution capable of providing a polyfunctional ester compound in which the content ratio of each of the pentafunctional to 7 functional polyfunctional 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.

  Examples of the carboxylic acid compound include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, 3-methylbutanoic acid, 2-methylbutyric acid, pivalic acid, hexanoic acid, 4-methylvaleric acid, 2-ethylbutyric acid, 2, 2-dimethylbutyric acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, icosanoic acid, behenic acid, Saturated fatty acids such as lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicylic acid, and lactesic acid; unsaturated fatty acids such as oleic acid, elaidic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid Cyclohexanecarboxylic acid, hexahydroisophthalic acid, hexahydrote Alicyclic carboxylic acids such as phthalic acid, 3,4,5,6-tetrahydrophthalic acid; benzoic acid, toluic acid, cumic acid, phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, trimellitic acid, hemimellitic acid, etc. Aromatic carboxylic acid; and the like.

  Of these carboxylic acid compounds, saturated or unsaturated fatty acids are preferred. The saturated or unsaturated fatty acid is preferably a saturated or unsaturated fatty acid having 10 to 30 carbon atoms, more preferably 12 to 26 carbon atoms, still more preferably 14 to 25 carbon atoms, and particularly preferably 18 to 24 carbon atoms. In this invention, it is 14-25.

  Specific examples of preferable fatty acids include myristic acid (carbon number 14), palmitic acid (carbon number 16), stearic acid (carbon number 18), icosanoic acid (carbon number 20), behenic acid (carbon number 22), lignoceric acid. Saturated higher fatty acids such as (24 carbon atoms); higher unsaturated fatty acids such as oleic acid (18 carbon atoms) and erucic acid (22 carbon atoms). Among these, stearic acid, icosanoic acid, behenic acid, lignoceric acid, and erucic acid are preferable.

  When a polyfunctional fatty acid ester 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, and the cohesiveness increases or It may be whitened.

  The polyfunctional ester compound preferably increases the esterification reaction rate between the polyhydric alcohol and the carboxylic acid compound (for example, fatty acid) so that the hydroxyl value is 8.0 mgKOH / g or less. Therefore, it is preferable to react an excess amount of the carboxylic acid compound with respect to the number of hydroxyl groups of the polyhydric alcohol during the esterification reaction, and purify the reaction product after the reaction. As the carboxylic acid compound, not only a compound having a free carboxyl group but also a compound capable of undergoing an esterification reaction with an alcoholic hydroxyl group such as a chloride (acid chloride) thereof can be used.

  The polyfunctional ester compound to be used is preferably a polyfunctional fatty acid ester of a tetrahydric or higher polyhydric alcohol and a fatty acid. Examples of such polyfunctional fatty acid esters include aliphatic polyhydric alcohols such as pentaerythritol, dipentaerythritol, and tripentaerythritol, and myristic acid, palmitic acid, stearic acid, icosanoic acid, behenic acid, and lignoceric acid. Saturated higher fatty acids or esterified products with higher unsaturated fatty acids such as oleic acid and erucic acid can be mentioned. Preferred polyfunctional fatty acid esters include, for example, pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, dipentaerythritol hexamyristate, dipentaerythritol hexastearate, Examples include dipentaerythritol hexabehenate.

  Commercially available products of polyfunctional fatty acid esters include, for example, WEP6 (trade name; pentaerythritol tetrastearate), WEP5 (trade name; pentaerythritol tetrabenate), WEP4 (trade name; Enterythritol tetrapalmitate), WEP1 (trade name; Pentaerythritol tetramyristate) and the like.

  As the polyfunctional ester compound, a polyfunctional fatty acid ester mixture of a polyhydric alcohol mixture containing two or more tetrahydric or higher polyhydric alcohols and a fatty acid can be used. As such a polyfunctional fatty acid ester mixture, a polyfunctional fatty acid ester mixture of a polyhydric alcohol mixture containing at least each of polyhydric alcohols having a valence of 4 to 8 and a fatty acid is preferable.

  The polyfunctional fatty acid ester mixture to be used is preferably an esterified product of a polyhydric alcohol mixture containing at least tetrafunctional to octafunctional polyhydric alcohol and a fatty acid. The polyhydric alcohol mixture may contain a small amount of 1 to 3 functional and / or 9 or more functional polyhydric alcohols.

  The polyfunctional fatty acid ester mixture to be used has a content ratio 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 ester. The content ratio of the compound is 15% by weight or more, preferably 18% by weight or more, more preferably 20% by weight or more. The polyfunctional fatty acid ester mixture preferably contains 5 to 7 functional polyfunctional fatty acid esters 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. Is desirable. The polyfunctional fatty acid ester mixture preferably contains pentafunctional or higher polyfunctional fatty acid esters in a proportion of 80% by weight or more in total.

  As for the polyfunctional fatty acid ester mixture to be used, it is desirable that 90% or more, preferably 95% or more, more preferably 98% or more of the fatty acid residues have 16 to 25 carbon atoms. The carbon number of the fatty acid residue is preferably 20 to 25, more preferably 20 to 22.

  The ratio of the polyfunctional fatty acid ester of each function and the ratio of the number of carbon atoms of the fatty acid 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 desirable to actually measure these values for the ester.

  When the polyfunctional fatty acid ester mixture to be used has the selected composition, the object of the present invention can be better achieved. If the content ratio of the tetrafunctional or lower fatty acid ester is too large, or the content ratio of the 8-functional or higher fatty acid ester is too small, the durability and blocking resistance after standing in a high temperature atmosphere may be reduced, A whitening phenomenon may also be seen. When the proportion of the fatty acid residue having 16 to 25 carbon atoms in the polyfunctional fatty acid ester mixture is too small, the blocking resistance after standing in a high temperature atmosphere may be remarkably deteriorated or the durability may be lowered. In addition, the whitening phenomenon of the developing roll tends to occur.

  In order to obtain a polyfunctional fatty acid ester mixture, it is preferable to use the glycerin polycondensate (polyglycerin) described above as a polyhydric alcohol having a valence of 4 or more. The reason is that polyglycerin is generally obtained as a mixture of glycerin polycondensates (polyhydric alcohol mixture) having different degrees of polycondensation. Polyglycerol can easily prepare glycerin polycondensate mixtures having different degrees of polycondensation by controlling polycondensation conditions.

  Preferable specific examples of the polyfunctional fatty acid ester mixture include, for example, polyglycerol behenate, polyglycerol stearate, polyglycerol icosanoate, polyglycerol lignocerate, polyglycerol erucate, and the like. Can be mentioned. Of these, polyglycerol behenate is particularly preferred.

  The solubility of the polyfunctional ester compound to be used in styrene is preferably 5 g or more, more preferably 10 g or more, and still more preferably when expressed in terms of the amount of styrene 100 g measured at 35 ° C. (g / 100 gST; 35 ° C.). It is 15 g or more, particularly preferably 20 g or more. If the amount of the polyfunctional ester compound dissolved in styrene at 35 ° C. is too small, the solubility of the polyfunctional ester compound in a polymerizable monomer containing styrene as a main component generally decreases. For this reason, 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 polyfunctional ester compound in the polymerizable monomer. Moreover, the polyfunctional ester compound having an excessively small amount dissolved in styrene is difficult to uniformly disperse in the produced polymerized toner even when heated and dissolved in the polymerizable monomer.

  The average molecular weight of the polyfunctional ester compound used is preferably 500 to 6,000, more preferably 2,000 to 5,000. When the polyfunctional ester compound is a polyfunctional fatty acid ester mixture, the average molecular weight is preferably 2,300 to 4,000, more preferably 2,500 to 3,500.

  If the average molecular weight of the polyfunctional ester compound is too low, it is difficult to lower the fixing temperature, and the offset resistance becomes insufficient. If the average molecular weight of the polyfunctional ester compound is too low, the melting point of the polyfunctional ester compound itself becomes low, and the polyfunctional ester compound has a high melting point. The functional ester compound is likely to precipitate (bleed), and as a result, the electrostatic image developing toner may be aggregated or the bleed-out polyfunctional ester compound crystal may grow greatly.

  If the polyfunctional ester compound is precipitated from the electrostatic image developing toner during printing, it will contaminate each part of the apparatus and cause toner filming on the developing roll and the photoreceptor surface. The average molecular weight of the polyfunctional ester compound can be obtained as a standard polystyrene equivalent value measured using gel permeation chromatography (GPC). The average molecular weight of the polyfunctional ester compound can also be calculated by calculation from the average molecular weight (calculated value) of the polyhydric alcohol used for the esterification and the molecular weight of the fatty acid.

  It is preferable that the polyfunctional ester compound to be used has a maximum endothermic peak in a region of 50 to 80 ° C. when the temperature rises in a DSC curve measured by a differential scanning calorimeter. A polyfunctional ester compound having a maximum endothermic peak temperature of 50 to 80 ° C. can contribute to the low-temperature fixability of the electrostatic image developing toner. The maximum endothermic peak temperature is preferably 55 to 78 ° C, particularly preferably 60 to 75 ° C.

  The monofunctional ester compound used is an ester compound of a monohydric alcohol and a carboxylic acid compound. The ester compound is monofunctional because the alcohol used is a monohydric alcohol and has one hydroxyl group (functional group), and the ester compound has one ester bond in the molecule. It is called an ester compound.

  Examples of the monohydric alcohol include undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol, behenyl alcohol, ceryl alcohol, Monovalent saturated aliphatic alcohols such as sil alcohols are included. The monohydric alcohol is preferably a higher saturated aliphatic alcohol having preferably 10 to 29 carbon atoms, more preferably 11 to 26, and particularly preferably 13 to 25 carbon atoms.

  Examples of the carboxylic acid compound that forms an ester bond with a monohydric alcohol include the aforementioned saturated fatty acid, unsaturated fatty acid, and aromatic carboxylic acid. Of these carboxylic acid compounds, saturated or unsaturated fatty acids are preferred. The saturated or unsaturated fatty acid is preferably a saturated or unsaturated fatty acid having 10 to 30 carbon atoms, more preferably 12 to 26 carbon atoms, still more preferably 14 to 25 carbon atoms, and particularly preferably 18 to 24 carbon atoms. In this invention, it is 14-25.

  Specific examples of preferable fatty acids include saturated higher fatty acids such as myristic acid, palmitic acid, stearic acid, icosanoic acid, behenic acid and lignoceric acid; higher unsaturated fatty acids such as oleic acid and erucic acid. Among these, stearic acid, icosanoic acid, behenic acid, lignoceric acid, and erucic acid are preferable.

  When a monofunctional fatty acid ester 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 and the cohesion may be increased. The monofunctional ester compound preferably increases the esterification reaction rate between the monohydric alcohol and the carboxylic acid compound (for example, fatty acid) so that the hydroxyl value thereof is 8.0 mgKOH / g or less.

  The monofunctional ester compound used is preferably a monofunctional fatty acid ester of a monohydric alcohol and a fatty acid. Examples of such monofunctional fatty acid esters include stearyl stearate (stearyl stearate), stearyl behenate, behenyl behenate (behenyl behenate), and behenyl stearate. Examples of commercially available products include WEP3 (trade name; behenyl behenate) manufactured by NOF Corporation.

  The monofunctional ester compound used preferably has a maximum endothermic peak in the region of 50 to 80 ° C. in the DSC curve measured with a differential scanning calorimeter.

  The solubility of the monofunctional ester compound used in styrene is preferably 5 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.).

  As the ester wax, a polyfunctional ester compound and a monofunctional ester compound are used in combination. The polyfunctional ester compound and the monofunctional ester compound may be used separately in predetermined amounts, but they may be mixed in advance to form a eutectic.

  In order to form a eutectic, a predetermined amount of each of a polyfunctional ester compound and a monofunctional ester compound is placed in a container and heated by a heating means such as an oil bath to prepare a molten mixture. The molten mixture is rapidly cooled and solidified by a method such as charging into ice water. The coagulum is dried as necessary. The obtained solidified product is a eutectic mixture in which a polyfunctional ester compound and a monofunctional ester compound are mixed in a eutectic state. In the eutectic, it is known that the two components are not simply mixed, but a binding force acts between both crystal grains.

  Whether or not the eutectic has been formed can be determined by performing DSC measurement on the eutectic mixture using a differential scanning calorimeter. Specifically, a DSC curve is obtained by DSC measurement of the eutectic mixture, the DSC curve does not have a shoulder, shows one maximum endothermic peak, and has a single endothermic peak temperature (melting point Tm). It can be determined that a eutectic is formed. The eutectic endothermic peak temperature is preferably in the range of 55 to 75 ° C.

  If the endothermic peak temperature of the eutectic (eutectic mixture) is too low, the storability of the toner for developing an electrostatic image is lowered, causing a hot offset phenomenon in which the toner is fused to the fixing roll, and adversely affecting the printing performance. There is also a case. On the other hand, if the endothermic peak temperature of the eutectic is too high, the low-temperature fixability of the toner for developing electrostatic image is lowered, and it is necessary to set the temperature of the fixing roll to a high temperature at the time of fixing. May not be able to respond.

  The total use ratio of the polyfunctional ester compound and the monofunctional ester compound is usually 0.5% with respect to 100 parts by weight of the polymerizable monomer forming the binder resin or binder resin of the electrostatic charge image developing toner. -40 parts by weight, preferably 1-30 parts by weight, more preferably 2-20 parts by weight, particularly preferably 4-15 parts by weight. If the use ratio is too small, it will be difficult to obtain a toner for developing an electrostatic charge image in which low-temperature fixability, storage stability, and printing durability are highly balanced. If the use ratio is too large, offset resistance is reduced, toner filming on the surface of the photoreceptor occurs, and these ester compounds are likely to precipitate from the toner surface.

2. Colored resin particles:
The toner for developing an electrostatic charge image may be colored resin particles containing a binder resin, a colorant, and an ester wax (polyfunctional ester compound and monofunctional 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.

  Typical methods for producing an electrostatic charge image developing toner include a pulverization method and a polymerization method. In the pulverization method, toner particles are produced by melt-kneading, pulverizing, and classifying components such as a binder resin, a colorant, and ester wax. 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 image developing toner of the present invention may be a core-shell type toner (capsule toner) in which a resin coating layer (polymer 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 is obtained by suspension polymerization of a polymerizable monomer composition containing at least a polymerizable monomer, a colorant, and an ester wax in an aqueous dispersion medium containing a dispersion stabilizer. be able to. The polymerizable monomer composition contains various additives such as a crosslinkable monomer, macromonomer, molecular weight modifier, charge control agent, other mold release agent, lubricant, and dispersion aid as necessary. Can be made.

  The polymerized toner having a core-shell structure can be produced by a spray drying method, an interfacial reaction method, an in situ polymerization method, a phase separation method, or the like. In particular, the in situ polymerization method and the phase separation method are preferable because of high production efficiency. Specifically, it was obtained by suspension polymerization of a polymerizable monomer composition containing at least a polymerizable monomer, a colorant, and an ester wax in an aqueous dispersion medium containing a dispersion stabilizer. It can be obtained by using colored resin particles as core particles and subjecting the polymerizable monomer for shell to suspension polymerization in the presence of the core particles. A polymer layer formed by polymerization of the monomer for shell becomes a resin coating layer (shell).

  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 both-end alcohols such as 1,4-butanediol and 1,9-nonanediol; N, N-divinylaniline; Divinyl compounds such as divinyl ether; compounds having 3 or more vinyl groups;

  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.

  These colorants are usually 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), Spiro Black TRH (manufactured by Hodogaya Chemical), T-77 (manufactured by Hodogaya Chemical), and Bontron S-. 34 (manufactured by Orient Chemical), Bontron E-81 (manufactured by Orient Chemical), Bontron E-84 (manufactured by Orient Chemical), Bontron E-89 (manufactured by Orient Chemical), Bontron F-21 (manufactured by 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 Nippon Carlit Co., Ltd .; JP-A-11-15192 Quaternary ammonium (salt) group-containing copolymers described in JP-A-3-175456, JP-A-3-243594, 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. .

  The ester wax composed of the polyfunctional ester compound and the monofunctional ester compound used acts as a mold release agent, so the use of other mold release agents is not necessary. An agent may be included. 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 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; water Metal hydroxides such as aluminum oxide, magnesium hydroxide and ferric hydroxide; water-soluble polymers such as polyvinyl alcohol, methylcellulose and gelatin; anionic surfactants, nonionic surfactants, amphoteric surfactants, etc. Surfactants; 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 the suspension polymerization method, first, a polymerizable monomer, a colorant, an ester wax and, if necessary, other additive components are mixed to obtain a polymerizable monomer. A composition is prepared. 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 diameter of about 50 to 1,000 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, and is preferably 5 ° C. or higher. More preferably, it is particularly preferably 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.

  The polymerization initiator used for the polymerization of the polymerizable monomer for shell includes persulfates such as potassium persulfate and ammonium persulfate; 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide ], 2,2'-azobis- [2-methyl-N- [1,1-bis (hydroxymethyl) 2-hydroxyethyl] propionamide] and the like water-soluble polymerization initiators; be able to. 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 an aqueous dispersion containing colored polymer particles (including core-shell type) produced by polymerization contains a dispersion stabilizer, a large number of dispersion stabilizer fine particles are formed on the surface of the colored polymer particles. It is attached. 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 washing water is filtered. In the water washing step, it is preferable to wash with water until the electrical conductivity of the filtrate (filtered washing water) becomes 1,000 μS / cm or less, and to filter the washing 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 colored resin particles (including core-shell type colored resin particles) 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 / Dn) of the volume average particle size (Dv) to the number average particle size (Dn) of the colored resin particles of the present invention is usually 1 or more and 1.7 or less, preferably 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 colored resin particles is too large, the resolution tends to be lowered. When the particle size distribution of the colored resin particles is large, the ratio of the large particle size increases, and the resolution tends to be lowered.

  The average circularity of the colored resin particles is preferably 0.96 to 1.00, more preferably 0.97 to 1.00, and particularly preferably 0.98 to 1.00 from the viewpoint of image reproducibility. The circularity is defined as a value obtained by dividing the circumference of a circle having the same projected area as the particle image by the circumference of the projected image of the particle. The average circularity is a method for quantitatively expressing the shape of the particles, and is an index indicating the degree of unevenness of the colored resin particles. The average circularity is 1 when the colored resin particles are completely spherical, and becomes smaller as the surface shape of the colored resin particles becomes more complicated. For the average circularity, the circularity (Ci) of each particle measured for a particle group having an equivalent circle diameter of 0.6 μm or more was determined for each of n particles from the following calculation formula 1, and then averaged from the following calculation formula 2. Obtain the circularity (Ca).

Formula 1:
Circularity (Ci) = perimeter of circle equal to projected area of particle / perimeter of projected particle image

Formula 2:

  In the calculation formula 2, fi is the frequency of particles having a circularity (Ci). The circularity and the average circularity can be measured using a flow type particle image analyzer “FPIA-2000”, “FPIA-2100”, “FPIA-3000” manufactured by Sysmex Corporation.

  If the average circularity of the colored resin particles is too small, the fine line reproducibility by printing may be deteriorated, and the fluidity and transferability of the electrostatic image developing toner are likely to be lowered. If the average circularity of the colored resin particles is too large, the cleaning property of the electrostatic image developing toner remaining on the photoreceptor tends to be lowered. When the average circularity of the colored resin particles is within the above range, it is preferable for highly balancing the flowability, transferability, and cleaning properties of the electrostatic image developing toner.

  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 0.00. It is 05 μm (20 to 50 nm). If the shell thickness is too large, the fixing property is lowered, and if it is too small, the storage 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 polymerizable monomer for shells in the presence of the core particles, and superimposing on the surface of the core particles. A method of forming a combined layer (shell) (in situ polymerization method) is preferred.

  The electrostatic image developing toner of the present invention has a low fixing temperature, excellent anti-blocking property (preservability) after storage at high temperatures, and excellent continuous printing characteristics. The toner for developing an electrostatic image of the present invention preferably has a degree of aggregation after storage at 55 ° C. for 8 hours, preferably 10% by weight or less, more preferably 5% by weight or less, particularly preferably 2% by weight or less, and in many cases 1% by weight. %, And is excellent in blocking resistance at high temperatures.

3. Toner for electrostatic image development:
The toner for developing an electrostatic charge image of the present invention can be used as a one-component developer or a two-component developer. 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 the 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 (silica) 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.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, reference examples, and comparative examples. However, the present invention is not limited to these examples. In the following, “parts” and “%” are based on weight unless otherwise specified. The test method and evaluation method are as follows.

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

(2) Acid value (mgKOH / g) and hydroxyl value (mgKOH / g):
The acid value was measured in accordance with JOCS 2.3.1-96, which is a standard oil and fat analysis technique of the Japan Oil Chemical Association (JOCS) measurement. Moreover, the hydroxyl value was measured based on JOCS 2.3.3.6-96.

(3) Ratio of the number of functional groups in the polyfunctional fatty acid ester mixture:
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. The ether phase was directly subjected to GC-MS (gas chromatography / mass spectrometry) measurement. 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 silylation was performed by heating at 100 ° C. for 20 minutes. GC-MS 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. By this method, the ratio of 20 to 25 carbon atoms of saturated fatty acid residues in the polyfunctional fatty acid ester mixture was measured at the same time.

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)

(4) Maximum endothermic peak temperature:
A sample of 6 to 8 mg is weighed into a sample holder, and it is increased from −20 ° C. to 100 ° C. at 10 ° C./min using a differential scanning calorimeter (trade name: RDC-220, manufactured by Seiko Instruments Inc.). Measurement was performed under warming conditions to obtain a DSC curve. In the DSC curve obtained by DSC measurement, when there was no shoulder and the endothermic peak temperature (melting point Tm) could be specified from one maximum endothermic peak, it was determined that eutectic formation was performed.

(5) Volume average particle size (Dv) and particle size distribution (Dv / Dn):
About 0.1 g of a measurement sample (colored resin particles) was weighed and taken in a beaker, and 1 mL of an alkylbenzene sulfonate aqueous solution (manufactured by Fuji Film Co., Ltd., trade name: dry well) was added as a dispersant. After adding 10-30 mL of Isoton II to the beaker and dispersing for 3 minutes with an ultrasonic disperser with an output of 20 W, using a particle size measuring device (Beckman Coulter, trade name: Multisizer), The volume average particle diameter (Dv) and the number average particle diameter (Dn) of the colored resin particles are measured under the conditions of aperture diameter: 100 μm, medium: Isoton II, number of measured particles: 100,000 particles, and the particle size distribution ( Dv / Dn) was calculated.

(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 Sysmex Corporation). As a measuring method, 10 mL of ion-exchanged water is prepared in advance in a container, and after adding a surfactant, preferably an alkylbenzene sulfonate, as a dispersant, 0.2 g of a measurement sample is added and uniformly dispersed. . As a dispersion means, an ultrasonic dispersion machine was used, and dispersion treatment was performed under conditions of an output of 60 W and 3 minutes. The concentration of the colored resin particles at the time of measurement was adjusted to 3,000 to 10,000 particles / μL. The circularity of 1,000 to 10,000 colored resin particles was measured. Using this data, the average circularity was determined.

(7) Minimum fixing temperature:
A fixing test was conducted using a printer modified so that the temperature of the fixing roll portion of a commercially available non-magnetic one-component developing type printer could be changed. In the fixing test, black solids (print density 100%) are printed, the temperature of the fixing roll of the modified printer is changed by 5 ° C., the toner fixing rate at each temperature is measured, and the temperature-fixing rate. I went for a relationship. The fixing rate was calculated from the ratio of the image density before and after the tape was peeled off in the black solid (printing density 100%) printing area. That is, when the image density before tape peeling is ID (front) and the image density after tape peeling is ID (back), the fixing ratio can be calculated by the following calculation formula 3.
Formula 3: Fixing rate (%) = (ID (rear) / ID (front)) × 100

  The tape peeling operation means that an adhesive tape (manufactured by Sumitomo 3M Co., Ltd., trade name: Scotch Mending Tape 810-3-18) is applied to the measurement part of the test paper, and is attached by pressing at a constant pressure, and then at a constant speed. It is a series of operations for peeling the adhesive tape in the direction along the paper. The image density was measured using a reflection type image densitometer (manufactured by Macbeth, trade name: RD914). In this fixing test, the lowest fixing roll temperature at which the fixing rate exceeds 80% was defined as the minimum fixing temperature of the toner.

(8) Preservability:
After 10 g of toner was put in a sealable container (made of polyethylene, capacity 100 mL) and sealed, the container was submerged in a thermostatic water bath maintained at a temperature of 55 ° C. After 8 hours, the container was taken out from the thermostatic water bath, and the toner in the container was placed on a 42 mesh sieve. At this time, the toner is gently taken out of the container and carefully transferred to a sieve so as not to destroy the toner aggregation structure in the container. The sieve on which the toner was placed was vibrated for 30 seconds under a condition of an amplitude of 1 mm using a powder measuring machine (trade name: Powder Tester PT-R, manufactured by Hosokawa Micron Corporation), and the weight of the toner remaining on the sieve was measured. The weight of the aggregated toner was measured. The ratio (% by weight) of the weight of the aggregated toner to the weight of the toner initially placed in the container was calculated. The above measurement was performed three times for each sample, the weight ratio (% by weight) of the aggregated toner was calculated, and the average value was used as an index of storage stability.

(9) Durability printing test:
The durability printing test was performed by using a commercially available non-magnetic one-component developing type printer, filling a toner cartridge of a developing device with toner, and then setting printing paper. After being left for 24 hours in a normal temperature and normal humidity (N / N) environment at a temperature of 23 ° C. and a relative humidity of 50%, continuous printing was performed up to 17,000 sheets at a 5% print density in the same environment.

  Black solid printing (printing density 100%) was performed every 1,000 sheets, and the printing density of the black solid image was measured using a reflection type image densitometer (manufactured by Macbeth, trade name: RD914). Furthermore, after that, white solid printing (print density 0%) is performed, the printer is stopped in the middle of white solid printing, and the toner in the non-image area on the photosensitive member after development is manufactured by the adhesive tape Sumitomo 3M, Product name: Scotch mending tape 810-3-18), and then peeled off and affixed to printing paper.

  Next, the whiteness (B) of the printing paper on which the adhesive tape was affixed was measured with a whiteness meter (Nippon Denshoku Co., Ltd., trade name: ND-1). Similarly, only an unused adhesive table was attached to the printing paper, and its whiteness (A) was measured. The difference in whiteness (B−A) was defined as the fog value. Smaller values indicate better fogging. The number of continuously printed sheets capable of maintaining an image quality with a print density of 1.3 or more and a fog value of 5% or less was examined.

[Production Example 1]
100 parts of polyglycerin (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., trade name: # 500) and 490 parts of behenic acid are placed in a reaction vessel and reacted at 240 ° C. under a catalyst and a nitrogen stream so that the esterification rate is 95% or more. Was reacted to prepare a polyglycerol behenate compound (polyfunctional fatty acid ester mixture). When the endothermic peak temperature of this compound was measured using DSC, it was 71 ° C.

  The polyfunctional fatty acid ester mixture had a dissolution amount of 25 g with respect to 100 g of styrene at 35 ° C., a hydroxyl value of 2.6 mgKOH / g, and an acid value of 0.4 mgKOH / g. The ratio of the fatty acid ester for each functional group of the polyfunctional fatty acid ester mixture is 4.7% by weight for the tetrafunctional group or less, 24.5% by weight for the 5th function, 26.7% by weight for the 6th function, and 22% for the 7th function 4% by weight and 8 or more functional groups were 21.7% by weight. Moreover, the ratio of 20 to 25 carbon atoms of the saturated fatty acid residue in the polyfunctional fatty acid ester mixture was 98.6% by weight.

  70 parts of the resulting polyfunctional fatty acid ester mixture (polyglycerin behenate ester compound) and 30 parts behenyl behenate (product name: WEP3, manufactured by NOF Corporation) having an endothermic peak temperature of 73 ° C. are placed in a beaker. It heated until it melted using the bath, and the molten mixture was obtained. The obtained molten mixture was poured into ice water and rapidly cooled to obtain a solidified eutectic mixture, which was further air-dried.

  When the DSC measurement of the obtained eutectic mixture was performed, the endothermic peak temperature was 67 ° C., and it was confirmed to be in a eutectic state. The amount of behenyl behenate, which is a monofunctional ester compound, dissolved in 100 g of styrene at 35 ° C. was 10 g, the hydroxyl value was 3 mgKOH / g, and the acid value was 0.1 mgKOH / g.

[Example 1]
1. Preparation of polymerizable monomer composition for core Polymerizable monomer for core consisting of 76 parts of styrene and 24 parts of n-butyl acrylate, polymethacrylic acid ester macromonomer (product name AA6, manufactured by Toagosei Co., Ltd.) .25 parts, carbon black (trade name: # 25B, manufactured by Mitsubishi Chemical Corporation), 6 parts, and positive charge control resin (quaternary ammonium base-containing styrene / acrylic resin, manufactured by Fujikura Kasei Co., Ltd., product name FCA-161P) 8 parts were stirred with a stirrer having a stirring blade, mixed, and then uniformly dispersed with a media-type disperser. To the obtained mixed liquid, 8 parts of the ester mixture in the eutectic state prepared in Production Example 1 was added, mixed and dissolved to obtain a polymerizable monomer composition for core.

2. Preparation of aqueous dispersion medium While stirring an aqueous solution obtained by dissolving 8.6 parts of magnesium chloride (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water, 50 parts of ion-exchanged water was added to sodium hydroxide (hydroxylated). An aqueous solution in which 4.8 parts of (alkali metal salt) were dissolved was gradually added to prepare a dispersion of magnesium hydroxide colloid (hardly water-soluble metal hydroxide colloid).

3. Droplet formation step The polymerizable monomer composition for core is added to the magnesium hydroxide colloid dispersion at 25 ° C., and stirred by a stirrer equipped with a stirring blade until the resulting coarse droplets are stabilized. did. To this, 4.5 parts of t-butylperoxydiethyl acetate as a polymerization initiator, 1.0 part of tetraethylthiuram disulfide as a molecular weight regulator, and 0.5 part of divinylbenzene as a crosslinkable polymerizable monomer are added. Then, high-speed shearing stirring (product name Ebara Milder, manufactured by Ebara Seisakusho Co., Ltd.) was used for high-speed shearing stirring at a rotational speed of 15,000 rpm for 10 minutes to form droplets of the polymerizable monomer composition.

4). Preparation of polymerizable monomer for shell 1 part of methyl methacrylate as the polymerizable monomer for shell and 2,2′-azobis [2-methyl-N- (2-hydroxy) as the water-soluble polymerization initiator for shell Ethyl) -propionamide] (manufactured by Wako Pure Chemical Industries, trade name VA-086, water-soluble polymerization initiator) was prepared by dissolving 0.1 part in 10 parts of ion-exchanged water.

5. Suspension polymerization step A reactor equipped with a stirring device having a stirring blade was prepared. 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.

  The dispersion liquid in the reactor was heated by a jacket provided outside the reactor, so that the liquid temperature was 90 ° C. and the polymerization reaction of the polymerizable monomer composition for the core was started. When the polymerization reaction was continued and the polymerization conversion rate reached 95%, the above-mentioned polymerizable monomer for shell and the water-soluble polymerization initiator for shell were added while maintaining the temperature in the reaction system at 90 ° C. After continuing the polymerization reaction by maintaining the temperature in the reaction system at 90 ° C. for 3 hours, the polymerization reaction is stopped by lowering the temperature in the system to about 25 ° C. by circulating cooling water through the jacket. did. By 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 10.6.

6). Post-treatment step The obtained aqueous dispersion containing the 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.

  This 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 bubble level was maintained at a level of 90% to 95% of the height in the evaporator. 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 and neutralizing 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 size (Dv) is 7.6 μm, the particle size distribution (Dv / Dn) is 1.20, and the average circularity is 0.98.

7). Non-magnetic one-component developer 100 parts of colored polymer particles, 0.8 parts of silica fine particles hydrophobized (product name: TG820F), and silica fine particles hydrophobized (product name: NA50Y, Japan Aerosil) ) 1 part was added and mixed using a Henschel mixer to obtain a non-magnetic one-component developer. Table 1 summarizes the test results of the obtained developer (sometimes simply referred to as “toner”).

[Reference Example 1]
A colored polymer in the same manner as in Example 1 except that 8 parts of the ester mixture of Example 1 were changed to 6 parts of pentaerythritol tetrastearate (trade name: WEP6, manufactured by NOF Corporation) and 2 parts of stearyl stearate. Particles and a non-magnetic one-component developer were prepared and used for testing.

  Pentaerythritol tetrastearate had a dissolution amount of 2 g with respect to 100 g of styrene at 35 ° C., a hydroxyl value of 3 mgKOH / g, and an acid value of 0.1 mgKOH / g. Stearyl stearate had a dissolution amount of 15 g with respect to 100 g of styrene at 35 ° C., a hydroxyl value of 3 mgKOH / g, and an acid value of 0.1 mgKOH / g.

[Comparative Example 1]
Colored polymer particles and a non-magnetic one-component developer were prepared in the same manner as in Example 1 except that 8 parts of the ester mixture of Example 1 was changed to 3 parts of behenyl behenate and subjected to the test.

[Comparative Example 2]
The colored polymer particles and the non-magnetic one-component developer were prepared in the same manner as in Example 1 except that 8 parts of the ester mixture of Example 1 was changed to 8 parts of the polyglycerol behenate compound produced in Production Example 1. Prepared and submitted for testing.

[Comparative Example 3]
Colored polymer particles and a non-magnetic one-component developer were prepared in the same manner as in Example 1 except that 8 parts of the ester mixture of Example 1 was changed to 8 parts of pentaerythritol tetrastearate (WEP6). Provided.

(footnote)
A ₁ : behenic acid ester of polyglycerin A ₂ : pentaerythritol tetrastearate B ₁ : behenyl behenate B ₂ : stearyl stearate A ₁ + B ₁ = eutectic

[Discussion]
When the ester wax is only a monofunctional ester compound (Comparative Example 1), the minimum fixing temperature is as high as 200 ° C. When the ester wax is only a polyglycerin behenate ester (Comparative Example 2), which is a polyfunctional ester compound (polyfunctional fatty acid ester mixture) (Comparative Example 2), the minimum fixing temperature is 180 ° C., and the low-temperature fixing property is insufficient.

  In the case where the ester wax is only the polyfunctional ester compound pentaerythritol tetrastearate (Comparative Example 3), although the low-temperature fixability is excellent, the storage stability is poor and the printing durability is insufficient.

  On the other hand, when the ester wax is a eutectic mixture of a polyfunctional ester compound and a monofunctional ester compound (Example 1), it is excellent in low-temperature fixability, and also has high storage stability and printing durability. I understand that there is. When the ester wax is a combination of a polyfunctional ester compound and a monofunctional ester compound (Reference Example 1), it has excellent low-temperature fixability, excellent storability, and high printing durability.

  The toner for developing an electrostatic image of the present invention has a high level of low-temperature fixability, storage stability, and printing durability, and these properties are highly balanced. And can be suitably used as a developer.

Claims (6)

  In an electrostatic image developing toner containing a binder resin, a colorant, and colored resin particles containing an ester wax, and an external additive, the ester wax is a polyglycerol of a polyhydric alcohol having a valence of 4 or more, A polyfunctional fatty acid ester compound with a saturated or unsaturated fatty acid having 14 to 25 carbon atoms, a higher saturated aliphatic monohydric alcohol having 13 to 25 carbon atoms, and a saturated or unsaturated fatty acid having 14 to 25 carbon atoms; And a monofunctional fatty acid ester compound at a weight ratio in the range of 50:50 to 95: 5.   2. The electrostatic image developing toner according to claim 1, wherein the polyfunctional fatty acid ester compound is a polyfunctional fatty acid ester mixture of a polyhydric alcohol mixture containing at least each of polyhydric alcohols having a valence of 4 to 8 and a fatty acid.   The electrostatic image developing toner according to claim 2, wherein the polyfunctional fatty acid ester mixture contains pentafunctional to heptofunctional polyfunctional fatty acid esters in a proportion of 15% by weight or more.   4. The electrostatic image developing toner according to claim 3, wherein the polyfunctional fatty acid ester mixture contains a polyfunctional fatty acid ester having 5 or more functional groups in a proportion of 80% by weight or more in total.   The ester wax is a coagulum prepared from a molten mixture of the polyfunctional fatty acid ester compound and the monofunctional fatty acid ester compound, the coagulum being a single maximum when measured with a differential scanning calorimeter; 2. The electrostatic image developing toner according to claim 1, wherein the toner is an eutectic ester mixture exhibiting an endothermic peak temperature.   2. The toner for developing an electrostatic charge image according to claim 1, wherein each of the polyfunctional fatty acid ester compound and the monofunctional fatty acid ester compound has a solubility of 5 g or more in 100 g of styrene measured at 35.degree.