Toner for developing electrostatic images

Abstract

This relates to a toner for electrostatic image development that offers excellent resistance to bending of printed materials. [Solution] A toner for developing electrostatic images, comprising a binder resin containing an amorphous polyester composite resin A and a colorant, wherein the amorphous polyester composite resin A is a composite resin in which a polyester resin segment and a styrene acrylic resin segment are bonded together via covalent bonds, the styrene acrylic resin constituting the styrene acrylic resin segment is a copolymer of raw material monomers containing at least a styrene compound and (meth)acrylic acid (provided that if the raw material monomer contains an alkyl ester of (meth)acrylic acid, the number of carbon atoms in the alkyl group is 8 or less), the acid value of the styrene acrylic resin segment is 40 mg KOH / g or more, and the colorant contains an organic pigment P in which the amount of NH groups is 2.0 mmol / g or more when the total number of -NH- groups and -NH2 groups in one molecule is divided by the molecular weight.

Description

[Technical Field]

[0001] The present invention relates to an electrostatic image developing toner used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like. [Background technology]

[0002] In recent years, in the field of electrophotography, the development of electrostatic image developing toners that support high image quality and high-speed printing has been required as electrophotographic systems have advanced. To meet these demands, a composite resin in which a polyester resin segment with excellent low-temperature fixability is covalently bonded to a styrene-acrylic resin segment has been investigated (see Patent Document 1).

[0003] On the other hand, a toner containing a colorant having a predetermined amount of NH groups has been disclosed as an electrostatic image developing toner that has excellent low-temperature fixation properties and can form a highly robust printed coating on printing media (substrates) such as plastic films (see Patent Document 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-107920 [Patent Document 2] Japanese Patent Publication No. 2024-84148 [Overview of the project] [Problems that the invention aims to solve]

[0005] Toner is required not only to adhere to paper, but also to withstand bending of the printed material after it has been fixed. To ensure proper adhesion to paper, the meltability of the toner needs to be reduced, but on the other hand, the toner layer becomes brittle, and when the printed material is bent, the toner layer cracks, resulting in a deterioration of image quality.

[0006] This invention relates to a toner for electrostatic image development that has excellent bending resistance for printed materials. [Means for solving the problem]

[0007] The present invention relates to a toner for developing electrostatic images, comprising a binder resin containing an amorphous polyester composite resin A and a colorant, wherein the amorphous polyester composite resin A is a composite resin in which a polyester resin segment and a styrene-acrylic resin segment are bonded together via covalent bonds, the styrene-acrylic resin constituting the styrene-acrylic resin segment is a copolymer of raw material monomers containing at least a styrene compound and (meth)acrylic acid (provided that if the raw material monomer contains an alkyl ester of (meth)acrylic acid, the number of carbon atoms in the alkyl group is 8 or less), the acid value of the styrene-acrylic resin segment is 40 mgKOH / g or more, and the colorant contains an organic pigment P in which the amount of NH groups is 2.0 mmol / g or more when the total number of -NH- groups and -NH2 groups in one molecule is divided by the molecular weight. [Effects of the Invention]

[0008] The electrostatic image developing toner of the present invention exhibits excellent effects in terms of the bending resistance of printed materials. [Modes for carrying out the invention]

[0009] The electrostatic image developing toner of the present invention contains a binder resin and a colorant, which include an amorphous polyester composite resin A in which a polyester resin segment and a styrene-acrylic resin segment having an acid value of a predetermined or higher are covalently bonded together, and the colorant contains an organic pigment P having a predetermined amount of NH groups. The reason why the effects of the present invention are achieved is not clear, but it is presumed to be as follows. Note that the mechanism described below is a hypothesis and is not limited thereto.

[0010] In the present invention, the styrene-acrylic resin constituting the styrene-acrylic resin segment in the amorphous polyester composite resin A is a copolymer of raw material monomers containing at least a styrene compound and (meth)acrylic acid. However, when the raw material monomer contains an alkyl ester of (meth)acrylic acid, the number of carbon atoms in the alkyl group is 8 or less, so the styrene-acrylic resin segment does not have long-chain alkyl side chains with a large number of carbon atoms. As a result, the acid groups in the styrene-acrylic resin segment readily interact electrostatically with the organic pigment P which has a large amount of NH groups, and this interaction is further enhanced by the styrene-acrylic resin segment with a high acid value, i.e., the styrene-acrylic resin segment which has a large number of acid groups. Consequently, it is believed that during fixing, the amorphous polyester composite resin A forms a pseudo- and movable crosslinked structure via the organic pigment P, thereby increasing the toughness of the resin and improving the bending resistance of the printed material.

[0011] The crystalline or amorphous nature of a resin is determined by its crystallinity index. The crystallinity index is defined as the ratio of the resin's softening point to its maximum endothermic peak temperature (softening point (°C) / maximum endothermic peak temperature (°C)) in the measurement method described in the examples below. A crystalline resin is one in which the crystallinity index is between 0.6 and 1.4. An amorphous resin is one in which no endothermic peak is observed, or if observed, the crystallinity index is less than 0.6 or greater than 1.4. The crystallinity of a resin can be adjusted by the type and ratio of raw material monomers, as well as the manufacturing conditions (e.g., reaction temperature, reaction time, cooling rate). The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In crystalline resins, the maximum endothermic peak temperature is defined as the melting point.

[0012] Amorphous polyester composite resin A is a composite resin in which polyester resin segments and styrene-acrylic resin segments are bonded together via covalent bonds.

[0013] The polyester resin segment is formed by polycondensation of an alcohol component and a carboxylic acid component, which are raw material monomers of the polyester resin.

[0014] From the viewpoint of low-temperature fixing property, the alcohol component has the formula (I):

[0015] [Chemical formula]

[0016] (In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y represent the average number of moles of alkylene oxide added, and are positive numbers respectively. The value of the sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, still more preferably 4 or less, and even more preferably 2.5 or less) Preferably contains an alkylene oxide adduct of bisphenol A represented by the formula (I). Examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include polyoxypropylene adducts of 2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene adducts of 2,2-bis(4-hydroxyphenyl)propane, etc. It is preferable to use one or more of these.

[0017] The content of the alkylene oxide adduct of bisphenol A represented by the formula (I) in the alcohol component is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, and even more preferably 95 mol% or more, and 100 mol% or less.

[0018] Examples of other alcohol components include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, etc., and polyhydric alcohols such as bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trimethylolpropane, etc.

[0019] From the viewpoint of low-temperature fixing property, the carboxylic acid component preferably contains an aromatic dicarboxylic acid-based compound.

[0020] Examples of the aromatic dicarboxylic acid-based compound include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters having 1 to 3 carbon atoms in the alkyl group. Among these, terephthalic acid is preferable from the viewpoint of low-temperature fixing property.

[0021] The content of the aromatic dicarboxylic acid-based compound in the carboxylic acid component is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, and 100 mol% or less.

[0022] Examples of other carboxylic acid components include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid optionally substituted with a hydrocarbon group, adipic acid, sebacic acid, etc., polyvalent carboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, etc., anhydrides of these acids, and alkyl esters having 1 to 3 carbon atoms in the alkyl group.

[0023] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monohydric carboxylic acid-based compound.

[0024] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol and carboxylic acid components.

[0025] The equivalent ratio (COOH group / OH group) of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component is preferably 0.6 or higher, more preferably 0.7 or higher, even more preferably 0.8 or higher, and preferably 1.3 or lower, more preferably 1.2 or lower, from the viewpoint of adjusting the softening point of the polyester resin.

[0026] Polyester resin segments can be produced, for example, by polycondensing an alcohol component and a carboxylic acid component in an inert gas atmosphere, and optionally in the presence of an esterification catalyst, co-catalyst, polymerization inhibitor, etc., at a temperature preferably 160°C or higher, more preferably 200°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

[0027] Examples of esterification catalysts include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(triethanolamine) and titanium dihydroxybis(triethanolamine). The amount of esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the total amount of alcohol and carboxylic acid components. Examples of co-catalysts for the esterification catalyst include gallic acid. The amount of co-catalyst used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, per 100 parts by mass of the total amount of alcohol and carboxylic acid components. Examples of polymerization inhibitors include tert-butylcatechol. The amount of polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, based on 100 parts by mass of the total amount of alcohol and carboxylic acid components.

[0028] The polyester resin segment content in amorphous polyester composite resin A is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, from the viewpoint of low-temperature fixability, and preferably 98% by mass or less, more preferably 96% by mass or less, and even more preferably 94% by mass or less, from the viewpoint of improving the bending resistance of printed materials.

[0029] The styrene-acrylic resin constituting the styrene-acrylic resin segment is a copolymer of raw material monomers containing at least a styrene-based compound and (meth)acrylic acid. In this specification, "(meth)acrylic acid" refers to acrylic acid, methacrylic acid, or both.

[0030] Examples of styrene-based compounds include styrene, α-methylstyrene, vinyltoluene, and other styrene derivatives, with styrene being preferred.

[0031] The styrene compound content is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and preferably 98% by mass or less, more preferably 96% by mass or less, and even more preferably 94% by mass or less, in the raw material monomer.

[0032] The (meth)acrylic acid content is preferably 2% by mass or more, more preferably 4% by mass or more, even more preferably 6% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, in the raw material monomer.

[0033] The raw material monomers for styrene-acrylic resin may further contain alkyl (meth)acrylate.

[0034] However, if the raw material monomer of the styrene-acrylic resin further contains an alkyl ester of (meth)acrylic acid, the number of carbon atoms in the alkyl group is 8 or less, preferably 6 or less, more preferably 5 or less, and 1 or more, preferably 2 or more.

[0035] Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and (iso)octyl (meth)acrylate. In this specification, "(iso)" means that the product includes both cases in which this group is present and cases in which it is not, and the absence of these groups indicates that the product is normal.

[0036] Other raw material monomers include ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenically monocarboxylic acid esters such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone.

[0037] The addition polymerization reaction of the raw material monomers for styrene-acrylic resin can be carried out in the same reaction vessel as the polycondensation reaction of the raw material monomers for polyester resin, for example, in the presence of polymerization initiators such as dibutyl peroxide and dicumyl peroxide, chain transfer agents, crosslinking agents, etc., in the presence of an organic solvent or without a solvent. The temperature conditions are preferably 110°C or higher, more preferably 140°C or higher, and preferably 200°C or lower, more preferably 170°C or lower.

[0038] When using an organic solvent during the addition polymerization reaction, xylene, toluene, methyl ethyl ketone, acetone, etc., can be used. The amount of organic solvent used is preferably 10 to 50 parts by mass per 100 parts by mass of the raw material monomer of the styrene acrylic resin.

[0039] Furthermore, when using pre-made styrene-acrylic resin in the production of composite resins, it is preferable to produce the styrene-acrylic resin by bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization, and from the viewpoint of the reactivity of the raw material monomers, it is more preferable to produce it by solution polymerization.

[0040] In this invention, "solution polymerization" refers to a method of polymerization in which raw material monomers are heated in an organic solvent together with a polymerization initiator and a chain transfer agent.

[0041] Examples of polymerization initiators include peroxides such as di-tert-butyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile) and 4,4'-azobis(4-cyanovaleric acid).

[0042] Examples of chain transfer agents include cationic chain transfer agents such as 1-amino-2-methyl-2-propanethol, and anionic chain transfer agents such as 3-mercaptopropionic acid.

[0043] The amount of polymerization initiator and chain transfer agent used in solution polymerization is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of raw material monomer of styrene acrylic resin.

[0044] Examples of organic solvents used in solution polymerization include xylene, toluene, methyl ethyl ketone, and acetone. The amount of organic solvent used is preferably 50 parts by mass to 150 parts by mass per 100 parts by mass of the raw material monomer of the styrene acrylic resin.

[0045] The temperature conditions for solution polymerization are preferably 50°C or higher, more preferably 65°C or higher, and preferably 100°C or lower, more preferably 90°C or lower.

[0046] The acid value of the styrene-acrylic resin segment is preferably 40 mg KOH / g or more, more preferably 45 mg KOH / g or more, from the viewpoint of interaction with the organic pigment P, and preferably 400 mg KOH / g or less, more preferably 300 mg KOH / g or less, and even more preferably 250 mg KOH / g or less, from the viewpoint of low-temperature fixation. In this invention, the acid value of the styrene-acrylic resin segment refers to the acid value of the styrene-acrylic resin used in the production of the composite resin.

[0047] The content of styrene-acrylic resin segments in amorphous polyester composite resin A is preferably 2% by mass or more, more preferably 4% by mass or more, and even more preferably 6% by mass or more, from the viewpoint of improving the bending resistance of printed materials, and preferably 40% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, from the viewpoint of low-temperature fixing properties.

[0048] The composite resin is preferably a resin in which a polyester resin segment and a styrene acrylic resin segment are covalently bonded together by reactive monomers that can react with both the raw material monomers of the polyester resin and the raw material monomers of the styrene acrylic resin.

[0049] The two reactive monomers are preferably compounds having at least one functional group selected from the group consisting of hydroxyl groups, carboxyl groups, epoxy groups, primary amino groups, and secondary amino groups, preferably a hydroxyl group and / or a carboxyl group, more preferably a carboxyl group, and an ethylenically unsaturated bond within the molecule. More preferably, at least one selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid, and maleic anhydride is preferred, and even more preferably, at least one selected from the group consisting of acrylic acid, methacrylic acid, and fumaric acid is preferred from the viewpoint of reactivity in polycondensation and addition polymerization reactions. However, when used together with a polymerization inhibitor, polycarboxylic acid compounds having an ethylenically unsaturated bond, such as fumaric acid, function as raw material monomers for polyester resins. In this case, fumaric acid, etc., are not two reactive monomers, but raw material monomers for polyester resins.

[0050] In this invention, the (meth)acrylic acid contained in the raw material monomer of the styrene-acrylic resin also acts as both reactive monomers.

[0051] Methods for producing amorphous polyester composite resin A, which is a composite of polyester resin segments and styrene acrylic resin segments, include (i) a method by polymer reaction between polyester resin and styrene acrylic resin, (ii) a method in which raw material monomers of polyester resin are reacted in the presence of styrene acrylic resin, and (iii) a method in which a portion of the raw material monomers of polyester resin are reacted, and then the styrene acrylic resin and the remaining raw material monomers of polyester resin are added and the reaction is carried out.

[0052] In method (i), it is preferable that the polymerization reactions of the polyester resin and the styrene-acrylic resin are carried out in independent reaction systems. If the polymerization reactions of the styrene-acrylic resin and the polyester resin are in independent reaction systems, the two polymerization reactions do not need to proceed and complete simultaneously in time; the reaction temperature and time can be appropriately selected according to the respective reaction mechanisms to allow the reactions to proceed and complete. Furthermore, in the polymer reaction of method (i), there are no particular restrictions on the method of mixing the polyester resin and the styrene-acrylic resin. For example, one method is to isolate the polyester resin obtained by polycondensation of the raw material monomers (alcohol component and carboxylic acid component) of the polyester resin, and then mix the polyester resin with the styrene-acrylic resin. Another method is to obtain a polyester resin by polycondensation of the raw material monomers of the polyester resin, and then add and mix the styrene-acrylic resin without isolating the obtained polyester resin.

[0053] In method (iii), an example is a method in which the alcohol component is reacted with a portion of the carboxylic acid component, and then the styrene-acrylic resin and the remainder of the carboxylic acid component are added to carry out the reaction.

[0054] Among these methods, from the viewpoint of controlling molecular weight, molecular weight distribution, and copolymerizability of monomers, and widening the fixing temperature range while maintaining excellent low-temperature fixing properties, amorphous polyester composite resin A is preferably a reaction product of polyester resin and styrene acrylic resin, and is preferably produced by the method (i) described above. That is, it is preferable to produce it by a method including the following steps I and II. The addition polymerization reaction in step I and the polycondensation reaction in step II are as described above. Step I: A step to obtain styrene-acrylic resin (A) by addition polymerization of raw material monomers for styrene-acrylic resin. Step II: After polycondensing the raw material monomers (alcohol component and carboxylic acid component) of the polyester resin, the styrene-acrylic resin obtained in Step I is added and the reaction is carried out to obtain the composite resin.

[0055] In amorphous polyester composite resin A, the mass ratio of the styrene-acrylic resin segment to the polyester resin segment (styrene-acrylic resin segment / polyester resin segment) is preferably 2 / 98 or higher, more preferably 4 / 96 or higher, even more preferably 6 / 94 or higher, and preferably 40 / 60 or lower, more preferably 20 / 80 or lower, and even more preferably 15 / 85 or lower, from the viewpoint of improving the dispersibility of the raw materials in the toner. In the above calculation, the mass of the polyester resin segment is the amount obtained by subtracting the amount of reaction water (calculated value) dehydrated by the polycondensation reaction from the mass of the raw material monomer of the polyester resin used.

[0056] The softening point of amorphous polyester composite resin A is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, from the viewpoint of hot offset resistance, and preferably 150°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower, from the viewpoint of low-temperature fixation.

[0057] The glass transition temperature of amorphous polyester composite resin A is preferably 40°C or higher, more preferably 50°C or higher, from the viewpoint of storage stability and durability, and preferably 80°C or lower, more preferably 70°C or lower, from the viewpoint of low-temperature fixation.

[0058] The acid value of amorphous polyester composite resin A is preferably 1 mg KOH / g or more, more preferably 2 mg KOH / g or more, from the viewpoint of low-temperature fixability, and preferably 20 mg KOH / g or less, more preferably 15 mg KOH / g or less, from the viewpoint of storage properties.

[0059] The content of amorphous polyester composite resin A is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, in the binder resin.

[0060] The binder resin may further contain amorphous polyester resin B other than amorphous polyester composite resin A.

[0061] Examples of amorphous polyester resin B include amorphous polyester resin, amorphous polyester composite resin in which a polyester resin segment and an addition polymerization resin segment are bonded together via covalent bonds, and amorphous polyester resin is preferred from the viewpoint of low-temperature fixability. Such amorphous polyester resin can be obtained by using the same raw material monomers (alcohol component and carboxylic acid component) as the polyester resin segment of amorphous polyester composite resin A, and adjusting the softening point by changing the raw material monomers, reaction temperature, reaction time, etc.

[0062] In this invention, the polyester resin may be a polyester resin that has been modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins that have been grafted or blocked with phenol, urethane, epoxy, etc., by methods described in Japanese Patent Publication No. 11-133668, Japanese Patent Publication No. 10-239903, Japanese Patent Publication No. 8-20636, etc. Among modified polyester resins, urethane-modified polyester resins obtained by urethane elongation of polyester resin with a polyisocyanate compound are preferred.

[0063] The softening point of amorphous polyester resin B is preferably 70°C or higher, more preferably 90°C or higher, from the viewpoint of hot offset resistance, and preferably 120°C or lower, more preferably 110°C or lower, from the viewpoint of low-temperature fixing properties.

[0064] The glass transition temperature of amorphous polyester resin B is preferably 40°C or higher, more preferably 50°C or higher, from the viewpoint of toner storage properties, and preferably 80°C or lower, more preferably 70°C or lower, from the viewpoint of electrostatic stability.

[0065] The acid value of amorphous polyester resin B is preferably 1 mg KOH / g or more, more preferably 3 mg KOH / g or more, from the viewpoint of electrostatic stability, and preferably 20 mg KOH / g or less, more preferably 18 mg KOH / g or less, from the viewpoint of hygroscopic resistance.

[0066] The content of amorphous polyester resin B is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, in the binder resin.

[0067] Other binder resins include crystalline polyester resins, vinyl resins such as styrene-acrylic resins, polyamide resins, epoxy resins, polycarbonate resins, polyurethane resins, and composite resins containing two or more of these resins.

[0068] The binder resin content in the toner is preferably 60% by mass or more, more preferably 70% by mass or more, and preferably 98% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less.

[0069] The coloring agent contains an organic pigment P having a specific amount of NH groups.

[0070] The amount of NH groups in organic pigment P is 2.0 mmol / g or more, preferably 4.0 mmol / g or more, more preferably 5.0 mmol / g or more, and preferably 25.0 mmol / g or less, more preferably 15.0 mmol / g or less, and even more preferably 13.0 mmol / g or less. Here, the amount of NH groups is the value obtained by dividing the total number of -NH- groups and -NH2 groups in one molecule by the molecular weight.

[0071] The organic pigment P is not particularly limited as long as it has the above-mentioned amount of NH groups, but from the viewpoint of image density, for example, as a yellow pigment, examples include benzimidazolone pigment, isoindoline pigment, condensed disazo pigment, etc.

[0072] Examples of benzimidazolone pigments include CI Pigment Yellow 180 (total number of -NH- and -NH2 groups in one molecule = 6, molecular weight = 733, NH group amount = 8.2 mmol / g).

[0073] Examples of isoindoline pigments include CI Pigment Yellow 185 (total number of -NH- and -NH2 groups in one molecule = 4, molecular weight = 337, NH group amount = 11.9 mmol / g).

[0074] Examples of azo pigments include CI Pigment Yellow 74 (total number of -NH- and -NH2 groups in one molecule = 1, molecular weight = 386, NH group amount = 2.6 mmol / g) and CI Pigment Yellow 150 (total number of -NH- and -NH2 groups in one molecule = 4, molecular weight = 282, NH group amount = 14.2 mmol / g).

[0075] Examples of disazo pigments include CI Pigment Yellow 155 (total number of -NH- and -NH2 groups in one molecule = 2, molecular weight = 717, NH group amount = 2.8 mmol / g).

[0076] Examples of condensed disazo pigments include CI Pigment Yellow 93 (total number of -NH- and -NH2 groups in one molecule = 4, molecular weight = 937, NH group amount = 4.3 mmol / g) and CI Pigment Yellow 95 (total number of -NH- and -NH2 groups in one molecule = 4, molecular weight = 917, NH group amount = 4.4 mmol / g).

[0077] Examples of magenta pigments include quinacridone-based pigments, naphthol AS-based pigments, azo-based pigments, and diketopyrrolopyrrole-based pigments.

[0078] Examples of quinacridone-based pigments include CI Pigment Red 122 (total number of -NH- and -NH2 groups in one molecule = 2, molecular weight = 340, NH group amount = 5.9 mmol / g).

[0079] Examples of naphthol AS-based pigments include CI Pigment Red 146 (total number of -NH- and -NH2 groups in one molecule = 2, molecular weight = 611, NH group amount = 3.3 mmol / g), CI Pigment Red 176 (total number of -NH- and -NH2 groups in one molecule = 4, molecular weight = 573, NH group amount = 7.0 mmol / g), and CI Pigment Red 269 (total number of -NH- and -NH2 groups in one molecule = 3, molecular weight = 581, NH group amount = 5.2 mmol / g).

[0080] Examples of azo pigments include CI Pigment Red 170 (total number of -NH- and -NH2 groups in one molecule = 2, molecular weight = 454, NH group amount = 4.4 mmol / g) and CI Pigment Red 184 (total number of -NH- and -NH2 groups in one molecule = 2, molecular weight = 581, NH group amount = 3.4 mmol / g).

[0081] Examples of diketopyrrolopyrrole pigments include CI Pigment Red 254 (total number of -NH- and -NH2 groups in one molecule = 2, molecular weight = 357, NH group amount = 5.6 mmol / g).

[0082] From the viewpoint of improving the bending resistance of printed materials, the content of organic pigment P is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of binder resin.

[0083] The toner of the present invention may contain colorants other than the organic pigment P, to the extent that it does not impair the effects of the present invention, but the content of the organic pigment P is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less, in the colorants. Other colorants include carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, carmine 6B, etc.

[0084] From the viewpoint of improving the bending resistance of printed materials, the colorant content is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the binder resin.

[0085] In addition to the binder resin (binder) and colorant, the toner of the present invention may also contain additives such as a mold release agent, charge control agent, magnetic powder, flowability improver, conductivity modifier, reinforcing filler such as fibrous material, antioxidant, and cleaning performance improver.

[0086] Examples of mold release agents include hydrocarbon waxes and their oxides, such as polypropylene wax, polyethylene wax, ethylene propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; ester waxes such as carnauba wax, montane wax and their deoxidizing waxes, and fatty acid ester waxes; and fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts, etc., which can be used individually or in combination of two or more.

[0087] The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of toner transferability, and preferably 160°C or lower, more preferably 140°C or lower, and even more preferably 120°C or lower, from the viewpoint of low-temperature fixation.

[0088] The release agent content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less, per 100 parts by mass of binder resin, from the viewpoint of low-temperature fixation and offset resistance of the toner and dispersibility in the binder resin.

[0089] The charge control agent is not particularly limited and may contain either a positively charged charge control agent or a negatively charged charge control agent.

[0090] Positively charged charge control agents include nigrosine dyes, such as "Nigrosine Base EX," "Oil Black BS," "Oil Black SO," "Bontron N-01," "Bontron N-04," "Bontron N-07," "Bontron N-09," "Bontron N-11," and "Bontron N-79" (all manufactured by Orient Chemical Industries, Ltd.); triphenylmethane-based dyes containing tertiary amines as side chains; quaternary ammonium salt compounds, such as "Bontron P-51" (manufactured by Orient Chemical Industries, Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX." Examples include VP435 (manufactured by Clariant), polyamine resins such as AFP-B (manufactured by Orient Chemical Industries, Ltd.), imidazole derivatives such as PLZ-2001 and PLZ-8001 (both manufactured by Shikoku Chemicals, Ltd.), and styrene-acrylic resins such as FCA-701PT and FCA-201-PS (manufactured by Fujikura Chemicals, Ltd.).

[0091] Furthermore, as negative charge control agents, metal-containing azo dyes, such as "Barifast Black 3804," "Bontron S-31," "Bontron S-32," "Bontron S-34," and "Bontron S-36" (all manufactured by Orient Chemical Industries, Ltd.), "Eisenspiron Black TRH," and "T-77" (manufactured by Hodogaya Chemical Co., Ltd.); metal compounds of benzyl acid compounds, such as "LR-147" and "LR-297" (both manufactured by Nippon Carlit Co., Ltd.); metal compounds of salicylic acid compounds, such as "Bontron E-81," "Bontron E-84," "Bontron E-88," and "Bontron E-304" (all manufactured by Orient Chemical Industries, Ltd.), and "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.); copper phthalocyanine dyes; and quaternary ammonium salts, such as "COPY CHARGE NX" Examples include VP434 (manufactured by Clariant), nitroimidazole derivatives, organometallic compounds, etc.

[0092] From the viewpoint of the charge stability of the toner, the content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of the binder resin.

[0093] The toner of the present invention may be obtained by any of the conventionally known methods, such as the melt-kneading method, the emulsification-coagulation method, or the suspension polymerization method, and may also be a toner having a core-shell structure. However, from the viewpoint of the mixability of the toner raw materials, pulverized toner is preferred, and pulverized toner obtained by the melt-kneading method, that is, pulverized toner obtained by a method including a step of melt-kneading at least a binder resin and a colorant and a step of pulverizing the resulting mixture, is more preferred. Specifically, for example, raw materials such as a binder resin, a colorant, a release agent, and a charge control agent can be uniformly mixed in a mixer such as a Henschel mixer, then melt-kneaded in a closed-type kneader, a single-screw or twin-screw extruder, an open-roll type kneader, etc., and then cooled, pulverized, and classified to produce the toner. In the production of toner, if the binder resin consists of two or more types of resins, a binder resin with pre-mixed resins may be used, or those resins may be directly used in the mixing of raw materials when producing the toner.

[0094] In order to improve the transferability of the toner of the present invention, it is preferable to use external additives. Examples of external additives include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles, and two or more may be used in combination. Among these, silica is preferred, and from the viewpoint of the transferability of the toner, hydrophobic silica that has been treated to hydrophobicity is more preferable.

[0095] Examples of hydrophobic agents used to hydrophobize the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0096] The average particle size of the external additive is preferably 10 nm or larger, more preferably 15 nm or larger, and more preferably 250 nm or smaller, more preferably 200 nm or smaller, and even more preferably 90 nm or smaller, from the viewpoint of the toner's chargeability, fluidity, and transferability.

[0097] External additive treatment, which involves mixing toner particles with external additives, can be carried out according to conventional methods, and a mixer such as a Henschel mixer can be used.

[0098] From the viewpoint of the toner's electrostatic properties, fluidity, and transferability, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, and preferably 5 parts by mass or less, and more preferably 3 parts by mass or less, per 100 parts by mass of toner particles before treatment with the external additive.

[0099] The volume-intermediate particle size (D) of the toner of the present invention 50 The volume median particle size (D) is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. 50 ) refers to the particle size at which the cumulative volume frequency calculated using volume fractions accounts for 50% when calculated from the smallest particle size. Furthermore, if the toner is treated with an external additive, the volume median particle size of the toner particles before treatment with the external additive is taken as the volume median particle size of the toner.

[0100] The toner of the present invention can be used as is as a one-component developing toner, or as a two-component developing toner mixed with a carrier, in image forming apparatuses using either a one-component developing method or a two-component developing method, respectively. [Examples]

[0101] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way by these examples. The physical properties of resins, etc., can be measured by the following methods.

[0102] [Softening point of resin] Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), 1 g of sample is heated at a heating rate of 6°C / min while a load of 1.96 MPa is applied by a plunger, and the sample is extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester is plotted against temperature, and the temperature at which half of the sample has flowed out is defined as the softening point.

[0103] [Maximum peak temperature of endothermic resin] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the sample is weighed into an aluminum pan and cooled from room temperature (25°C) to 0°C at a rate of 10°C / min, and maintained at 0°C for 1 minute. Then, measurements are taken at a rate of 10°C / min. Among the observed endothermic peaks, the temperature of the peak with the largest peak area is defined as the maximum endothermic peak temperature. For crystalline resins, the maximum endothermic peak temperature is defined as the melting point.

[0104] [Glass transition temperature of resins] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled to 0°C at a rate of 10°C / min. Next, the sample is heated at a rate of 10°C / min, and the endothermic peak is measured. The temperature at the intersection of the extension of the baseline below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the peak apex is defined as the glass transition temperature.

[0105] [Acid value of resins] The measurement will be performed according to the method of JIS K 0070:1992. However, the measurement solvent will be changed from the ethanol and ether mixture specified in JIS K 0070 to an acetone and toluene mixture (acetone:toluene = 1:1 (volume ratio)).

[0106] [Melting point of release agent] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a rate of 10°C / min. Next, the sample is heated again at a rate of 10°C / min, the amount of heat is measured, and the maximum peak temperature of endothermic heating is defined as the melting point.

[0107] [Medium volume particle size of resin particles, colorant particles, and mold release agent particles] (1) Measuring device: Laser diffraction particle size analyzer "LA-920" (manufactured by Horiba, Ltd.) (2) Measurement conditions: Take the sample dispersion into a measuring cell, add distilled water, and measure the volume mid-particle size (D) at a temperature where the absorbance is within the appropriate range. 50 ) Measure.

[0108] [Solid content concentration of resin dispersion, colorant dispersion, and mold release agent dispersion] Using the infrared moisture meter "FD-230" (manufactured by Kett Scientific Research Institute Co., Ltd.), 5g of the sample to be measured was dried at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, variation range 0.05%), and the moisture content (mass%) of the dispersion was measured. The solid content concentration was calculated according to the following formula. Solid concentration (mass%) = 100-moisture (mass%)

[0109] [Medium particle size by volume of aggregated particles] • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte solution to adjust the concentration to one that could measure the particle size of 30,000 particles in 20 seconds. Then, the 30,000 particles were measured, and the volume median particle size (D) was determined from the particle size distribution. 50 )

[0110] [Toner volume medium particle size (D 50 )〕 • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Dispersion: Prepared by dissolving polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] in the electrolyte to adjust the concentration to 5% by mass. • Dispersion conditions: Add 10 mg of the sample to 5 mL of the dispersion and disperse for 1 minute using an ultrasonic disperser (machine name: US-1 manufactured by SND Corporation, output: 80W). Then, add 25 mL of electrolyte and disperse for another minute using the ultrasonic disperser to prepare the sample dispersion. • Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles can be measured in 20 seconds. Then, the 30,000 particles are measured, and the volume median particle size (D) is determined from the particle size distribution. 50 )

[0111] [Toner circularity] The circularity of the toner particles will be measured under the following conditions. • Measurement device: Flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) • Preparation of dispersion: Prepare the dispersion of toner particles by diluting it with deionized water so that the solid content concentration is 0.001 to 0.05% by mass. • Measurement mode: HPF measurement mode

[0112] [Average particle size of external additives] The average particle diameter refers to the number-average particle diameter, which is calculated by measuring the particle size (average of the major and minor axes) of 500 particles (primary particles) from scanning electron microscope (SEM) images and using the number-average value of these measurements.

[0113] Manufacturing example of styrene-acrylic suspension Ten percent of the raw material monomers, chain transfer agents, and polymerization initiators shown in Table 1, along with an equal amount of methyl ethyl ketone, were placed in a 2-liter four-necked flask equipped with a dehydration tube with a nitrogen inlet, a stirrer, and a thermocouple, and the temperature was raised to 80°C. Then, a mixed solution was prepared using the remaining raw material monomers, chain transfer agents, and polymerization initiators shown in Table 1, along with an equal amount of methyl ethyl ketone, and this was added dropwise at a rate of 4.2 g / min. The mixture was then reacted at 80°C for 1 hour, and the pressure was further reduced at 20 kPa at 80°C for 4 hours to remove the methyl ethyl ketone from the system, yielding styrene-acrylic resins (resins a1-a6). A total of 700 g of raw material monomers was used.

[0114] [Table 1]

[0115] Examples of manufacturing amorphous polyester composite resins The alcohol component, carboxylic acid component, and esterification catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a dehydration tube with a nitrogen inlet tube, a stirrer, and a thermocouple. The mixture was heated to 235°C and reacted at 235°C for 8 hours. The pressure in the flask was then reduced, and a reduced-pressure reaction was carried out at 8 kPa for 1 hour. After that, the mixture was cooled to 210°C, the styrene-acrylic resins shown in Table 2 were added, the temperature was raised to 235°C, and the mixture was reacted at 235°C for 1 hour. The pressure in the flask was then reduced to 8 kPa, and the mixture was reacted until the softening point reached the temperature shown in Table 2, yielding amorphous polyester composite resins (resins A1-A6).

[0116] [Table 2]

[0117] Examples of amorphous polyester resin production As shown in Table 3, the alcohol component, the carboxylic acid component other than trimellitic anhydride, and the esterification catalyst were placed in a 10-liter four-necked flask equipped with a dehydration tube with a nitrogen inlet tube, a stirrer, and a thermocouple. The mixture was heated to 230°C in a mantle heater under a nitrogen atmosphere and polycondensed for 7 hours. After that, the temperature was lowered to 200°C, trimellitic anhydride was added, and the temperature was raised to 210°C to carry out the polycondensation reaction until the softening point reached the temperature shown in Table 3, thereby obtaining an amorphous polyester resin (resin B1).

[0118] [Table 3]

[0119] Examples 1-12, 15 and Comparative Examples 1, 2 100 parts by mass of the binder resin and coloring agent shown in Table 5, 1 part by mass of the charge control agent "E-304" (manufactured by Orient Chemical Industry Co., Ltd.), and 3 parts by mass of the release agent "WAX-C1" (manufactured by Kato Yoko Co., Ltd., carnauba wax, melting point: 83°C) were thoroughly mixed in a Henschel mixer, and then kneaded using a continuous double-roll open-roll kneader "Nidex" (manufactured by Nippon Coke Industries Co., Ltd.).

[0120] The continuous two-roll open-type kneader had a roll outer diameter of 0.14m and an effective roll length of 0.8m. The operating conditions were as follows: the high-speed roll (front roll) rotated at 75 r / min (peripheral speed 33 m / min), the low-speed roll (rear roll) rotated at 50 r / min (peripheral speed 22 m / min), and the roll gap was 0.1 mm. The heating and cooling media temperatures inside the rolls were set to 140°C on the raw material input side and 110°C on the kneaded material discharge side of the high-speed roll, and to 65°C on the raw material input side and 30°C on the kneaded material discharge side of the low-speed roll. The raw material mixture supply rate was 10 kg / h, and the average residence time was approximately 5 minutes.

[0121] The resulting mixture was cooled to 25°C and coarsely ground using a Rotoplex pulverizer (manufactured by Hosokawa Micron Corporation). Coarsely ground material with a particle size of 2 mm or less was obtained using a sieve with a mesh size of 2 mm. Fine grinding and upper limit classification (removal of coarse powder) were performed using a 400AFG counterjet mill (manufactured by Hosokawa Alpine Co., Ltd.). Further lower limit classification (removal of fine powder) was performed using a TTSP classifier (manufactured by Hosokawa Alpine Co., Ltd.) to obtain toner particles with a median volume particle size of 6.5 μm.

[0122] To 100 parts by mass of the obtained toner particles, 1.2 parts by mass of "R-972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobic treatment agent: DMDS, average particle size: 16 nm) and 1.4 parts by mass of "RY-50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobic treatment agent: silicone oil, average particle size: 40 nm) were added as external additives, and the mixture was treated with external additives by mixing in a Henschel mixer at 2300 r / min for 3 minutes to obtain toner.

[0123] Example 13 <Preparation of resin dispersion> In a 3-liter container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 100 g (50 parts by mass) of resin A1, 100 g (50 parts by mass) of resin B1, and 200 g of methyl ethyl ketone were placed and dissolved at 73°C for 2 hours. To the resulting solution, a 5% by mass aqueous sodium hydroxide solution was added to achieve a degree of neutralization of 60 mol% relative to the acid value of the resin, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, 700 g of deionized water was added over 50 minutes while stirring at 200 r / min to induce phase inversion emulsification. The resulting solution was then maintained at 73°C, and methyl ethyl ketone was removed under reduced pressure to obtain a dispersion. Subsequently, the dispersion was cooled to 30°C while continuing to stir, and then deionized water was added to achieve a solid content concentration of 20% by mass to obtain a resin dispersion.

[0124] <Preparation of colorant dispersion> In a 1-liter beaker, 122 g of colorant P1, 154.9 g of anionic surfactant "Neoperex (registered trademark) G-15" (manufactured by Kao Corporation, 15% by mass aqueous solution of sodium dodecylbenzenesulfonate), and 260 g of deionized water were mixed and dispersed at room temperature for 3 hours using a homogenizer. Then, deionized water was added to adjust the solid content concentration to 20% by mass, thereby obtaining a colorant dispersion. The volume median particle size (D 50 ) of the colorant particles in the obtained dispersion was 118 nm.

[0125] <Preparation of mold release agent dispersion> 50 g of mold release agent "WAX-C1" (manufactured by Kato Yoko Co., Ltd., carnauba wax, melting point: 83°C), 5 g of cationic surfactant (manufactured by Kao Corporation, trade name: Sanisol B50), and 200 g of deionized water were heated to 95°C, and the mold release agent was dispersed using a homogenizer. Then, it was subjected to dispersion treatment with a pressure discharge type homogenizer, and deionized water was added to obtain a mold release agent dispersion with a solid content concentration of 20% by mass. The volume median particle size (D 50 ) of the mold release agent particles in the obtained dispersion was 550 nm.

[0126] <Aggregation process> Into a 3-liter four-neck flask equipped with a reflux condenser, a stirrer, and a thermocouple, 549 g of resin dispersion, 23 g of colorant dispersion, 16 g of mold release agent dispersion, and 3.3 g of 15% by mass aqueous solution of sodium dodecylbenzenesulfonate "Neoperex G-15" (manufactured by Kao Corporation, anionic surfactant) were placed and mixed at a temperature of 25°C. Next, while stirring the obtained mixture, an aqueous solution prepared by dissolving 43 g of ammonium sulfate in 980 g of deionized water and adding a 4.8% by mass aqueous solution of potassium hydroxide to adjust the pH to 8.2 was added dropwise at 25°C over 10 minutes. Then, the temperature was raised to 58°C over 2 hours, and held at 58°C until the volume median particle size (D 50 ) of the aggregated particles reached 7.0 μm, thereby obtaining a dispersion of aggregated particles.

[0127] <Fusion process> To the resulting dispersion of aggregated particles, 22 g of polyoxyethylene lauryl ether sodium sulfate "Emal E-27C" (manufactured by Kao Corporation, anionic surfactant, effective concentration 27% by mass) and 1100 g of deionized water were added. The mixture was then heated to 75°C over 1 hour and maintained at 75°C until the circularity reached 0.970, thereby obtaining a dispersion of fused particles in which the aggregated particles had fused together.

[0128] The resulting dispersion of fused particles was cooled to 30°C, and the dispersion was filtered by suction to separate the solid components. The mixture was then washed with deionized water at 25°C and filtered by suction at 25°C for 2 hours. Subsequently, vacuum drying was performed at 33°C for 24 hours using a vacuum constant-temperature dryer "DRV622DA" (manufactured by ADVANTEC) to obtain the medium volume particle size (D 50 ) yielded toner particles with a size of 7.0 μm.

[0129] To 100 parts by mass of the obtained toner particles, 1.2 parts by mass of "R-972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobic treatment agent: DMDS, average particle size: 16 nm) and 1.4 parts by mass of "RY-50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobic treatment agent: silicone oil, average particle size: 40 nm) were added as external additives, and the mixture was treated with external additives by mixing in a Henschel mixer at 2300 r / min for 3 minutes to obtain toner.

[0130] Example 14 Instead of a continuous two-roll open-roll type kneader, a co-rotating twin-screw extruder "PCM-30" (manufactured by Ikegai Co., Ltd., shaft diameter 2.9 cm, shaft cross-sectional area 7.06 cm²) was used. 2 Toner was obtained in the same manner as in Example 1, except that the raw material mixture was melt-kneaded using ). The operating conditions of the twin-screw extruder were a barrel setting temperature of 100°C, a shaft rotation speed of 200 r / min (circumferential speed of shaft rotation of 0.30 m / sec), and a mixture feed rate of 10 kg / h.

[0131] Table 4 shows the details of the colorants used in the examples and comparative examples.

[0132] [Table 4]

[0133] Test example [Bending resistance of printed materials] A modified fuser unit of the "AR-505" copier (manufactured by Sharp Corporation) was modified to allow for external fixing, and toner was installed in this modified unit. A printed document was obtained in an unfixed state (print area: 20cm x 20cm, adhesion amount: 0.5mg / cm²). 2 ). Subsequently, the image was fixed using a fixer (fixing speed 300 mm / sec) adjusted to achieve a total fixing pressure of 40 kgf, with the fixing roll temperature set to 160°C. This image was then fixed at 50 g / cm². 2 The bending resistance of the printed material was measured by applying a load, folding it inward for 30 seconds, then unfolding it, and wiping away the damaged image with a soft cloth. The maximum width of the image defect was used as an indicator of the print's bending resistance. The results are shown in Table 5. A smaller maximum width of image defect indicates better bending resistance of the print. The fixing paper used was "CopyBond SF-70NA" (manufactured by Sharp Corporation, 75g / m²). 2 ) was used.

[0134] [Table 5]

[0135] Based on these results, it can be seen that the toners of Examples 1 to 15 exhibit good bending resistance of printed materials compared to Comparative Example 1, in which the acid value of the styrene-acrylic resin segment of the composite resin was too low, and Comparative Example 2, in which the amount of NH groups in the colorant was too small. [Industrial applicability]

[0136] The electrostatic image developing toner of the present invention is suitably used for developing latent images formed in electrostatic image developing methods, electrostatic recording methods, electrostatic printing methods, and the like.

Claims

1. A toner for developing electrostatic images containing an amorphous polyester composite resin A and a binder resin and a colorant, wherein the amorphous polyester composite resin A is a composite resin in which a polyester resin segment and a styrene acrylic resin segment are bonded together via covalent bonds, the styrene acrylic resin constituting the styrene acrylic resin segment is a copolymer of a raw material monomer containing at least a styrene compound and (meth)acrylic acid (provided that if the raw material monomer contains an alkyl ester of (meth)acrylic acid, the number of carbon atoms in the alkyl group is 8 or less), the acid value of the styrene acrylic resin segment is 40 mg KOH / g or more, and the colorant contains -NH- groups and -NH in one molecule ２ A toner for developing electrostatic images, containing an organic pigment P in which the amount of NH groups is 2.0 mmol / g or more, when the total number of groups is divided by the molecular weight to determine the amount of NH groups.

2. The toner for developing electrostatic images according to claim 1, wherein the coloring agent content is 2 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the binder resin.

3. The electrostatic image developing toner according to claim 1 or 2, wherein the content of organic pigment P in the colorant is 80% by mass or more.

4. The electrostatic image developing toner according to claim 1 or 2, wherein the amorphous polyester composite resin A is a reaction product of a polyester resin and a styrene acrylic resin.

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