WO2025115865A1 - Toner for electrostatic image development - Google Patents

Abstract

Provided are: a toner for electrostatic image development which comprises a binder resin and a colorant comprising the binder resin that includes an amorphous polyester resin A that is a product of polycondensation of poly(ethylene terephthalate), an alcohol ingredient, and a carboxylic acid ingredient, and the colorant that includes an organic yellow pigment that has an NH group amount of 4.0 to 15.0 mmol/g inclusive, the NH group amount being a value obtained by dividing the total number of -NH- groups and -NH₂ groups in one molecule by the molecular weight; and a method for producing the toner for electrostatic image development. The toner for electrostatic image development according to the present invention is suitable for use in, for example, developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, or the like.

Description

Toner for developing electrostatic images

The present invention relates to a toner for developing electrostatic images used to develop latent images formed in electrophotography, electrostatic recording, electrostatic printing, etc., and a method for producing the same.

In recent years, C.I. Pigment Yellow 74 has been widely used as a yellow pigment in toners for developing electrostatic images, but from the standpoint of weather resistance and safety, switching to other yellow pigments is being considered.

For example, Patent Document 1 proposes a yellow pigment that has three or more aromatic rings in one molecule and a molecular weight of 600 to 1,500.

JP 2020-154154 A

The present invention relates to
[1] A toner for developing electrostatic images, comprising a binder resin and a colorant, the binder resin comprising an amorphous polyester resin A which is a polycondensation product of polyethylene terephthalate, an alcohol component, and a carboxylic acid component, and the colorant comprising an organic yellow pigment having an NH group amount of 4.0 mmol/g or more and 15.0 mmol/g or less, where the NH group amount is the value obtained by dividing the total number of -NH- groups and -NH2 _groups in one molecule by the molecular weight; and [2] a method for producing the toner for developing electrostatic images according to [1], comprising the steps of melt-kneading at least the binder resin and the colorant, and pulverizing the obtained kneaded mixture.

Detailed Description of the Invention

Toners that contain organic yellow pigments have the problem of insufficient smear resistance in printed images.

The present invention relates to a toner for developing electrostatic images with excellent smear resistance and a method for producing the same.

The toner for developing electrostatic images of the present invention exhibits excellent effects in terms of smear resistance.

The toner for developing electrostatic images of the present invention (hereinafter simply referred to as "toner") is characterized by the combination of an amorphous polyester resin (amorphous polyester resin A) using polyethylene terephthalate (PET) and an organic yellow pigment with a high NH group content. The reason why the toner for developing electrostatic images of the present invention has excellent smear resistance is unclear, but is presumed to be as follows.

In the polycondensation reaction of an alcohol component, a carboxylic acid component, and PET, the PET undergoes depolymerization and is incorporated into the polyester resin chain through an ester exchange reaction, but the resin does not become completely randomized, and units that can be called PET segments exist in the resulting resin. These PET segments have a high concentration of ester groups and tend to interact with organic yellow pigments that have a high amount of NH groups. As a result, when fixed, the amorphous polyester resin A forms a pseudo-crosslinked structure via the organic yellow pigment, which is thought to improve the impact resistance of the printed material and provide excellent smear resistance.

Amorphous polyester resin A is a polycondensation product of PET, an alcohol component, and a carboxylic acid component.

PET is produced by the polycondensation reaction between an alcohol component and a carboxylic acid component, and/or by the depolymerization of a portion of PET. The ethylene glycol and terephthalic acid produced are then subjected to a polycondensation reaction as raw monomers and incorporated into the polyester resin. PET is an equimolar polycondensation product of ethylene glycol and terephthalic acid, and the amounts of the alcohol component and carboxylic acid component described below include the ethylene glycol and terephthalic acid that make up PET.

The PET may be new virgin PET or recycled PET.
Recycled PET is made by collecting used PET, washing it as necessary and separating it from other materials, then crushing it, and depolymerizing the crushed material down to its monomer units, which are then used to resynthesize new PET.

In the present invention, it is preferable that the PET has a relatively low IV value, i.e., a low molecular weight, compared to conventionally used PET. By introducing PET with a low IV value (low molecular weight) into the polyester resin, the depolymerization of the PET proceeds more uniformly.

From the above viewpoints, the IV value of PET is preferably 0.40 or more, more preferably 0.45 or more, even more preferably 0.50 or more, and even more preferably 0.55 or more, and from the viewpoints of low-temperature fixability and uniform depolymerization, it is preferably 0.85 or less, more preferably 0.80 or less, even more preferably 0.75 or less, even more preferably 0.70 or less, and even more preferably 0.65 or less. The IV value is the intrinsic viscosity and is an index of molecular weight. The IV value of PET can be adjusted by the polycondensation time, etc.

Commercially available PET products with an IV value of 0.40 to 0.85 include RAMAPET L1 (Indorama Ventures, IV value: 0.60), RAMAPET BF3067 (Indorama Ventures, IV value: 0.65), RAMAPET N2G (Indorama Ventures, IV value: 0.75), TRN-NTJ (Teijin, IV value: 0.53), TRN-RTJC (Teijin, IV value: 0.64), RAMAPET S1 (Indorama Ventures, IV value: 0.84), and UK-31 (Utsumi Recycle Systems, IV value: 0.67).

The content of low IV PET in the total amount of PET used in polycondensation is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass.

The PET content in the amorphous polyester resin A is, from the viewpoint of smearing, preferably 5 mol % or more, more preferably 10 mol % or more, even more preferably 20 mol % or more, and preferably 75 mol % or less, more preferably 70 mol % or less, even more preferably 65 mol % or less, even more preferably 50 mol % or less, even more preferably 40 mol % or less, and even more preferably 30 mol % or less, based on the total amount of the alcohol component, the carboxylic acid component, and the PET. When the amorphous polyester resin A is composed of two or more resins, the weighted average value of the PET contents of the respective resins is defined as the PET content of the amorphous polyester resin A.
In addition, since PET is a polycondensation product of ethylene glycol and terephthalic acid, dimethyl terephthalate, etc., the terephthalic acid-ethylene glycol unit (MW: 192) is calculated as 1 mole. Therefore, the number of moles of PET = the number of moles of ethylene glycol units = the number of moles of terephthalic acid units.

From the viewpoint of smearing, it is preferable that the alcohol component contains an alkylene oxide adduct of bisphenol A.

The alkylene oxide adduct of bisphenol A is represented by the formula (I):

(In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and/or a propylene group, x and y are the average number of moles of alkylene oxide added, each of which is a positive number, and 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, and even more preferably 4 or less.)
Preferred is a compound represented by the following formula:

From the viewpoint of low-temperature fixability, the content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 25 mol% or more, more preferably 40 mol% or more, even more preferably 55 mol% or more, and preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less. The alcohol component here includes the ethylene glycol units in PET.

Other alcohol components include aliphatic diols, alicyclic diols, bisphenol A, etc.

As the aliphatic diol, an aliphatic diol other than ethylene glycol is preferred, and examples thereof include 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

Examples of alicyclic diols include hydrogenated bisphenol A.

Carboxylic acid components include aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, etc.

Aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

Aliphatic dicarboxylic acid compounds include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, glutaric acid, adipic acid, sebacic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

The alcohol component and/or carboxylic acid component of the amorphous polyester resin A may contain a trivalent or higher raw material monomer in order to adjust the softening point.

Examples of trihydric or higher alcohols include sorbitol, pentaerythritol, glycerin, trimethylolpropane, etc.

Examples of trivalent or higher carboxylic acid compounds include trimellitic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

The content of trivalent or higher raw material monomers in the total amount of alcohol components, carboxylic acid components, and PET is preferably 2 mol% or more, more preferably 4 mol% or more, and is preferably 25 mol% or less, more preferably 20 mol% or less.

The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

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

The equivalent ratio (COOH groups/OH groups) of the carboxylic acid component (including the terephthalic acid units in the PET) to the alcohol component (including the ethylene glycol units in the PET) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, and is preferably 1.3 or less, more preferably 1.2 or less.

Amorphous polyester resin A can be produced, for example, by polycondensing an alcohol component, a carboxylic acid component, and PET in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and, if necessary, in the presence of a cocatalyst, polymerization inhibitor, etc., at a temperature of preferably 130°C or higher, more preferably 170°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(triethanolaminate) and titanium dihydroxybis(triethanolaminate). The amount of the 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, relative to 100 parts by mass of the total of the alcohol component, the carboxylic acid component, and the PET. Examples of the co-catalyst for the esterification catalyst include gallic acid. The amount of the 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, relative to 100 parts by mass of the total of the alcohol component, the carboxylic acid component, and the PET. Examples of the polymerization inhibitor 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, more preferably 0.1 parts by mass or less, per 100 parts by mass of the total amount of the alcohol component, the carboxylic acid component, and the PET.

In the present 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, or the like, by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. Among the modified polyester resins, urethane-modified polyester resins in which polyester resins have been urethane-extended with a polyisocyanate compound are preferred.

The ester group concentration of the amorphous polyester resin A is preferably 3.5 mmol/g or more, more preferably 3.7 mmol/g or more, and even more preferably 4.0 mmol/g or more, and is preferably 12.0 mmol/g or less, more preferably 10.0 mmol/g or less, and even more preferably 6.0 mmol/g or less. When two or more types of amorphous polyester resins A are used, the weighted average of the ester group concentrations of the respective amorphous polyester resins A is regarded as the ester group concentration of the amorphous polyester resin A.

In the present invention, the ester group concentration of the polyester resin is calculated using the following formula:

[In the formula, A is the total amount of ester bonds (mol) generated when all the raw monomers of the polyester resin have reacted, and B is the total mass (g) of the raw monomers that make up the polyester resin. The numbers in parentheses in the formula indicate the units of each value.]

The softening point of the amorphous polyester 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 charging stability, and is preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower, from the viewpoint of low-temperature fixability.

The crystallinity of a resin is represented by a crystallinity index defined as the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, that is, the value of [softening point/maximum endothermic peak temperature].
An amorphous resin is a resin in which no endothermic peak is observed, or, if an endothermic peak is observed, the crystallinity index is greater than 1.4 or less than 0.6.
On the other hand, a crystalline resin is a resin having a crystallinity index of 0.6 or more and 1.4 or less.
The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and the production conditions (e.g., reaction temperature, reaction time, cooling rate), etc. The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the case of a crystalline resin, the maximum endothermic peak temperature is the melting point.

From the viewpoint of low-temperature fixability and fixation width, the amorphous polyester resin A may be composed of resins with different softening points. The difference in softening points between the two types of resins is preferably 10°C or more, more preferably 20°C or more, and is preferably 60°C or less, more preferably 40°C or less.

The softening point of the amorphous resin with the higher softening point (Resin AH) is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher, from the viewpoint of fixing width, and is preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower, from the viewpoint of low-temperature fixing ability.

The softening point of the amorphous resin having the lower softening point (resin AL) is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, from the viewpoint of charging stability, and is preferably 130°C or lower, more preferably 125°C or lower, more preferably 120°C or lower, and even more preferably 110°C or lower, from the viewpoint of low-temperature fixing ability.

The mass ratio of resin AH to resin AL (resin AH/resin AL) is preferably 10/90 or more, more preferably 20/80 or more, even more preferably 30/70 or more, and is preferably 90/10 or less, more preferably 80/20 or less, even more preferably 75/25 or less.

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

The acid value of the amorphous polyester resin A is preferably 1 mgKOH/g or more, more preferably 3 mgKOH/g or more, from the viewpoint of electrostatic stability, and is preferably 20 mgKOH/g or less, more preferably 18 mgKOH/g or less, from the viewpoint of durability.

The content of amorphous polyester resin A in the binder resin is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of durability, and is preferably 100% by mass or less, more preferably 99% by mass or less, even more preferably 97% by mass or less, and even more preferably 95% by mass or less, from the viewpoint of low-temperature fixability.

From the viewpoint of low-temperature fixability, it is preferable that the binder resin further contains crystalline polyester resin C.

Crystalline polyester resin C is preferably a polycondensation product of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound.

Aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

The carbon number of the aliphatic diol is 2 or more, preferably 6 or more, and from the viewpoint of adjusting the ester group concentration, is preferably 14 or less, more preferably 12 or less.

From the viewpoint of improving the low-temperature fixing property of the toner, the aliphatic diol preferably has a hydroxyl group at the end of the carbon chain, and is more preferably an α,ω-straight-chain alkane diol.

The content of the aliphatic diol in the alcohol component is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more, and is 100 mol% or less.

Alcohol components other than aliphatic diols include alkylene oxide adducts of bisphenol A, aromatic diols such as bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trihydric or higher alcohols such as trimethylolpropane, etc.

Aliphatic dicarboxylic acid compounds include succinic acid (carbon number: 4), fumaric acid (carbon number: 4), adipic acid (carbon number: 6), suberic acid (carbon number: 8), azelaic acid (carbon number: 9), sebacic acid (carbon number: 10), dodecanedioic acid (carbon number: 12), tetradecanedioic acid (carbon number: 14), anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms. Here, when the aliphatic dicarboxylic acid compound is an alkyl ester, the number of carbon atoms of the alkyl group is not included in the above carbon number.

The carbon number of the aliphatic dicarboxylic acid compound is preferably 4 or more, more preferably 6 or more, and even more preferably 8 or more, and from the viewpoint of adjusting the ester group concentration, is preferably 14 or less, more preferably 12 or less.

The content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, even more preferably 80 mol% or more, and 100 mol% or less, from the viewpoint of hydrophobicity.

Other carboxylic acid components include aromatic dicarboxylic acid compounds such as phthalic acid, isophthalic acid, and terephthalic acid, and trivalent or higher carboxylic acid compounds such as trimellitic acid and pyromellitic acid.

The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monovalent carboxylic acid compound.

The equivalent ratio of the carboxyl groups of the carboxylic acid component to the hydroxyl groups of the alcohol component (COOH groups/OH groups) is preferably 0.8 or more, more preferably 0.9 or more, from the viewpoint of charging stability, and is preferably 1.2 or less, more preferably 1.1 or less, from the viewpoint of low-temperature fixability.

The polycondensation reaction conditions of the alcohol component and the carboxylic acid component of the crystalline polyester resin C are the same as those of the amorphous polyester resin A, except that the preferred reaction temperature is 120°C or higher, more preferably 180°C or higher, and 230°C or lower, more preferably 220°C or lower.

From the viewpoint of durability, the softening point of the crystalline polyester resin C is preferably 50°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 140°C or lower, more preferably 120°C or lower, and even more preferably 100°C or lower.

From the viewpoint of durability, the melting point of the crystalline polyester resin C is preferably 50°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 130°C or lower, more preferably 120°C or lower, and even more preferably 100°C or lower.

The acid value of the crystalline polyester resin C is preferably 1 mgKOH/g or more, more preferably 3 mgKOH/g or more, from the viewpoint of low-temperature fixability, and is preferably 30 mgKOH/g or less, more preferably 25 mgKOH/g or less, from the viewpoint of durability.

The content of crystalline polyester resin C in the binder resin is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of low-temperature fixability, and is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of durability.

The mass ratio of crystalline polyester resin C to amorphous polyester resin A (crystalline polyester resin C/amorphous polyester resin A) is, from the viewpoint of electrostatic stability, preferably 1/99 or more, more preferably 3/97 or more, even more preferably 5/95 or more, and is preferably 30/70 or less, more preferably 25/75 or less, even more preferably 20/80 or less.

Other binder resins include vinyl resins such as styrene acrylic resin, epoxy resin, polycarbonate, polyurethane, and composite resins containing two or more of these resins.

The total content of amorphous polyester resin A and crystalline polyester resin C in the binder resin is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass.

The content of the binder resin in the toner is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and is preferably less than 100% by mass, more preferably 98% by mass or less, even more preferably 95% by mass or less.

The colorant contains an organic yellow pigment having a specific amount of NH groups from the viewpoint of interaction with the amorphous polyester resin A.

The NH group amount of the organic yellow pigment is 4.0 mmol/g or more, preferably 5.0 mmol/g or more, more preferably 6.0 mmol/g or more, and 15.0 mmol/g or less, preferably 12.5 mmol/g or less, more preferably 10.0 mmol/g or less, where the NH group amount is the total number of -NH- groups and _-NH2 groups in one molecule divided by the molecular weight.

From the viewpoint of achieving the desired amount of NH groups, the organic yellow pigment is preferably at least one selected from the group consisting of benzimidazolone pigments, isoindoline pigments, and condensed disazo pigments.

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

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

Examples of condensed disazo pigments include C.I. Pigment Yellow 93 (total number of -NH- groups and -NH ₂ groups in one molecule = 4, molecular weight = 937, NH group amount = 4.3 mmol / g), C.I. Pigment Yellow 95 (total number of -NH- groups and -NH ₂ groups in one molecule = 4, molecular weight = 917, NH group amount = 4.4 mmol / g), and the like.

From the viewpoint of toner smearing properties, the organic yellow pigment used in the present invention is preferably at least one selected from benzimidazolone pigments and isoindoline pigments, and more preferably at least one selected from C.I. Pigment Yellow 180 (PY180) and C.I. Pigment Yellow 185 (PY185).

The content of the organic yellow pigment is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of amorphous polyester resin A.

The colorant may contain other colorants as long as the effect of the present invention is not impaired, but the content of the organic yellow pigment in the colorant is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass. Examples of other colorants include carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment green B, rhodamine B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, disazo yellow, etc.

The content of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the binder resin.

The toner for developing electrostatic images of the present invention may contain additives such as a release agent, a charge control agent, a magnetic powder, a flowability improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, and a cleaning improver, in addition to the binder resin and colorant.

Releasing agents include hydrocarbon waxes such as polypropylene wax, polyethylene wax, ethylene propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and oxides thereof; ester waxes such as carnauba wax, montan wax, and deoxidized waxes thereof, and fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts; and the like, which can be used alone or in combination of two or more kinds.

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 is preferably 160°C or lower, more preferably 140°C or lower, even more preferably 120°C or lower, and even more preferably 110°C or lower, from the viewpoint of low-temperature fixability.

The content of the release agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, relative to 100 parts by mass of the binder resin, from the viewpoints of the low-temperature fixing property and offset resistance of the toner, and dispersibility in the binder resin, and is 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.

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.

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", and "Bontron N-11" (all manufactured by Orient Chemical Industries Co., Ltd.); triphenylmethane dyes containing a tertiary amine as a side chain; quaternary ammonium salt compounds, such as "Bontron P-51" (Orient Chemical Industries Co., Ltd.); Examples of suitable resins include Cetyltrimethylammonium bromide, "COPY CHARGE PX VP435" (Clariant); polyamine resins, such as "AFP-B" (Orient Chemical Industries); imidazole derivatives, such as "PLZ-2001" and "PLZ-8001" (both manufactured by Shikoku Kasei Corporation); and styrene-acrylic resins, such as "FCA-701PT" and "FCA-201-PS" (Fujikura Kasei).

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

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.

The toner may be a toner obtained by any of the conventionally known methods such as the melt kneading method, emulsion aggregation method, suspension polymerization method, etc., and may also be a toner having a core-shell structure, but from the viewpoint of smearing, a pulverized toner obtained by the melt kneading method is preferred. In the case of a pulverized toner obtained by the melt kneading method, it is preferable to manufacture the toner by a method including a step of melt kneading at least a binder resin and a colorant and a step of pulverizing the obtained kneaded product. For example, the toner can be manufactured by uniformly mixing raw materials such as amorphous polyester resin A and a colorant, and, if necessary, a crystalline polyester resin, a release agent, a charge control agent, etc., in a mixer such as a Henschel mixer, and then melt kneading the raw materials in an internal kneader, a single-screw or twin-screw extruder, an open roll type kneader, etc., followed by cooling, pulverization, and classification.

In order to improve the transferability of the toner of the present invention, it is preferable to use an external additive. 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-based resin fine particles and polytetrafluoroethylene resin fine particles, and two or more types may be used in combination. Of these, silica is preferred, and from the viewpoint of the transferability of the toner, hydrophobic silica that has been subjected to a hydrophobic treatment is more preferred.

Hydrophobic treatment agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), methyltriethoxysilane, etc.

The average particle size of the external additive is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 15 nm or more, from the viewpoint of the chargeability, fluidity, and transferability of the toner, and is preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 90 nm or less.

The external additive process by mixing the toner particles with the external additives can be carried out according to conventional methods, and a mixer such as a Henschel mixer can be used.

From the viewpoint of the chargeability, fluidity, and transferability of the toner, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the toner particles before treatment with the external additive, and is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

The volume median particle diameter ( _D50 ) of the toner of the present invention is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. In this specification, the volume median particle diameter ( _D50 ) means a particle diameter at which the cumulative volume frequency calculated by volume fraction is 50% calculated from the smallest particle diameter. In addition, when the toner is treated with an external additive, the volume median particle diameter of the toner particles before the treatment with the external additive is taken as the volume median particle diameter of the toner.

The toner of the present invention can be used as it is as a single-component developing toner, or mixed with a carrier as a two-component developing toner, in image forming devices using either a single-component developing method or a two-component developing method.

　With respect to the above-mentioned embodiment, the present invention further discloses the following toner for developing electrostatic images and a method for producing the same.

<1> A toner for developing electrostatic images, comprising a binder resin and a colorant, the binder resin comprising an amorphous polyester resin A which is a polycondensate of polyethylene terephthalate, an alcohol component, and a carboxylic acid component, and the colorant comprising an organic yellow pigment having an NH group amount of 4.0 mmol/g or more and 15.0 mmol/g or less, where the NH group amount is a value obtained by dividing the total number of -NH- groups and -NH2 _groups contained in one molecule by the molecular weight.

<2> The toner for developing electrostatic images according to <1>, wherein the polyethylene terephthalate has a low IV value of 0.40 or more, preferably 0.45 or more, more preferably 0.50 or more, even more preferably 0.55 or more, and is preferably 0.85 or less, more preferably 0.80 or less, more preferably 0.75 or less, even more preferably 0.70 or less, and even more preferably 0.65 or less.
<3> The toner for developing electrostatic images according to the above item <2>, wherein the content of the low IV polyethylene terephthalate is 90% by mass or more, preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably 100% by mass, based on the total amount of polyethylene terephthalate to be subjected to polycondensation.
<4> The toner for developing electrostatic images according to any one of <1> to <3>, wherein the content of polyethylene terephthalate is 5 mol % or more, preferably 10 mol % or more, more preferably 20 mol % or more, and 75 mol % or less, preferably 70 mol % or less, more preferably 65 mol % or less, even more preferably 50 mol % or less, even more preferably 40 mol % or less, and even more preferably 30 mol % or less, based on the total amount of the alcohol component, the carboxylic acid component, and the polyethylene terephthalate.
<5> The toner for developing electrostatic images according to any one of <1> to <4>, wherein the alcohol component contains an alkylene oxide adduct of bisphenol A represented by the formula (I).
<6> The toner for developing electrostatic images according to the above item <5>, wherein the content of the alkylene oxide adduct of bisphenol A in the alcohol component (including the ethylene glycol unit in polyethylene terephthalate) is 25 mol % or more, preferably 40 mol % or more, more preferably 55 mol % or more, and is 95 mol % or less, preferably 90 mol % or less, more preferably 85 mol % or less.
<7> The toner for developing electrostatic images according to any one of <1> to <6>, wherein the amorphous polyester resin A has an ester group concentration of 3.5 mmol/g or more, preferably 3.7 mmol/g or more, more preferably 4.0 mmol/g or more, and is 12.0 mmol/g or less, preferably 10.0 mmol/g or less, more preferably 6.0 mmol/g or less.
<8> The toner for developing electrostatic images according to any one of <1> to <7>, wherein the softening point of the amorphous polyester resin A is 70° C. or higher, preferably 90° C. or higher, more preferably 100° C. or higher, and is 170° C. or lower, preferably 160° C. or lower, more preferably 150° C. or lower.
<9> The toner for developing an electrostatic image according to any one of <1> to <8>, wherein the amorphous polyester resin A contains resins having different softening points, the difference between the softening points being 10° C. or more, preferably 20° C. or more and 60° C. or less, preferably 40° C. or less.
<10> The toner for developing electrostatic images according to the above item <9>, wherein the amorphous resin having a higher softening point (resin AH) has a softening point of 100° C. or higher, preferably 110° C. or higher, more preferably 120° C. or higher, and is 170° C. or lower, preferably 160° C. or lower, more preferably 150° C. or lower.
<11> The toner for developing electrostatic images according to the above <9> or <10>, wherein the softening point of the amorphous resin having a lower softening point (resin AL) is 70° C. or higher, preferably 90° C. or higher, more preferably 100° C. or higher, and is 130° C. or lower, preferably 125° C. or lower, more preferably 120° C. or lower, and even more preferably 110° C. or lower.
<12> The toner for developing electrostatic images according to any one of <9> to <11>, wherein a mass ratio (resin AH/resin AL) of the amorphous resin having a higher softening point (resin AH) to the amorphous resin having a lower softening point (resin AL) is 10/90 or more, preferably 20/80 or more, more preferably 30/70 or more, and is 90/10 or less, preferably 80/20 or less, more preferably 75/25 or less.
<13> The toner for developing electrostatic images according to any one of <1> to <12>, wherein the glass transition temperature of the amorphous polyester resin A is 40° C. or higher, preferably 50° C. or higher, and 80° C. or lower, preferably 70° C. or lower.
<14> The electrostatic image developing toner according to any one of <1> to <13>, wherein the content of the amorphous polyester resin A in the binder resin is 70% by mass or more, preferably 75% by mass or more, more preferably 80% by mass or more, and 100% by mass or less, preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less.
<15> The toner for developing an electrostatic image according to any one of <1> to <14>, wherein the binder resin contains a crystalline polyester resin C.
<16> The toner for developing electrostatic images according to the above <15>, wherein the crystalline polyester resin C is a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound.
<17> The toner for developing electrostatic images according to the above <16>, wherein the aliphatic diol has a hydroxyl group at a terminal of a carbon chain, and is preferably an α,ω-straight-chain alkanediol.
<18> The toner for developing electrostatic images according to the above <16> or <17>, wherein the content of the aliphatic diol in the alcohol component is 80 mol % or more, preferably 90 mol % or more, more preferably 95 mol % or more and 100 mol % or less.
<19> The toner for developing electrostatic images according to any one of <16> to <18>, wherein the content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is 50 mol % or more, preferably 60 mol % or more, more preferably 70 mol % or more, and still more preferably 80 mol % or more and 100 mol % or less.
<20> The toner for developing electrostatic images according to any one of <15> to <19>, wherein the crystalline polyester resin C has a softening point of 50° C. or more, preferably 65° C. or more, more preferably 70° C. or more, and is 140° C. or less, preferably 120° C. or less, more preferably 100° C. or less.
<21> The electrostatic image developing toner according to any one of <15> to <20>, wherein the melting point of the crystalline polyester resin C is 50° C. or more, preferably 65° C. or more, more preferably 70° C. or more, and is 130° C. or less, preferably 120° C. or less, more preferably 100° C. or less.
<22> The electrostatic image developing toner according to any one of <15> to <21>, wherein the content of the crystalline polyester resin C in the binder resin is 1% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, and is 30% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less.
<23> The toner for developing electrostatic images according to any one of the above <15> to <22>, wherein a mass ratio of the crystalline polyester resin C to the amorphous polyester resin A (crystalline polyester resin C/amorphous polyester resin A) is 1/99 or more, preferably 3/97 or more, more preferably 5/95 or more, and is 30/70 or less, preferably 25/75 or less, more preferably 20/80 or less.
<24> The toner for developing electrostatic images according to any one of <15> to <23>, wherein the total content of the amorphous polyester resin A and the crystalline polyester resin C in the binder resin is 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and still more preferably 100% by mass.
<25> The toner for developing an electrostatic image according to any one of <1> to <24>, wherein the organic yellow pigment has an NH group amount of preferably 5.0 mmol/g or more, more preferably 6.0 mmol/g or more, and preferably 12.5 mmol/g or less, more preferably 10.0 mmol/g or less.
<26> The toner for developing electrostatic images according to any one of <1> to <25>, wherein the organic yellow pigment is at least one pigment selected from the group consisting of benzimidazolone pigments, isoindoline pigments, and condensed disazo pigments.
<27> The toner for developing an electrostatic image according to any one of <1> to <25>, wherein the organic yellow pigment is at least one selected from benzimidazolone pigments and isoindoline pigments, and is preferably at least one selected from C. I. Pigment Yellow 180 (PY180) and C. I. Pigment Yellow 185 (PY185).
<28> The electrostatic image developing toner according to any one of <1> to <27>, wherein the content of the organic yellow pigment is 1 part by mass or more, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and 20 parts by mass or less, preferably 18 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of the amorphous polyester resin A.
<29> The electrostatic image developing toner according to any one of <1> to <28>, wherein the content of the colorant is 1 part by mass or more, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and 20 parts by mass or less, preferably 18 parts by mass or less, more preferably 15 parts by mass or less, relative to 100 parts by mass of the binder resin.
<30> The method for producing a toner for developing an electrostatic image according to any one of <1> to <29>, further comprising the steps of melting and kneading at least the binder resin and the colorant, and pulverizing the resulting kneaded mixture.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples. The physical properties of the resins and the like can be measured by the following methods.

[PET IV value]
The viscosity is calculated from the following formula: A solution of 4 g/L in a mixed solvent of phenol/tetrachloroethane at a mass ratio of 60/40 is dissolved and measured using an Ubbelohde viscometer.
IV=(-1+√(1+4kη))/(2kC)
(wherein k=0.33, C=0.004 g/mL, and η=(t ₁ /t ₀ )−1 (t ₀ : number of seconds it takes for the solvent alone to fall, t ₁ : number of seconds it takes for the sample solution to fall).)

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

[Maximum endothermic peak temperature of resin]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), 0.01 to 0.02 g of a sample is weighed into an aluminum pan and cooled from room temperature (25°C) to 0°C at a temperature drop rate of 10°C/min, and maintained at 0°C for 1 minute. Thereafter, measurements are performed at a temperature increase rate of 10°C/min. The temperature of the peak with the largest peak area among the observed endothermic peaks is taken as the maximum endothermic peak temperature. For crystalline resins, the maximum endothermic peak temperature is taken as the melting point.

[Glass transition temperature of resin]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), 0.01 to 0.02 g of a sample is weighed into an aluminum pan, heated to 200°C, and cooled from that temperature at a rate of 10°C/min to 0°C. The sample is then heated at a rate of 10°C/min, and the endothermic peak is measured. The glass transition temperature is the temperature at the intersection of an extension of the baseline below the maximum endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the apex of the peak.

[Acid value of resin]
Measurement is performed based on the method of JIS K 0070: 1992. However, only the measurement solvent is changed from the mixed solvent of ethanol and ether specified in JIS K 0070 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for amorphous resins, and a mixed solvent of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins.

[Melting point of release agent]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), 0.02 g of a sample is weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a temperature drop rate of 10°C/min. The sample is then heated at a temperature rise rate of 10°C/min, the amount of heat is measured, and the maximum endothermic peak temperature is taken as the melting point.

[Volume Median Particle Size and CV Value of Resin Particles, Colorant Particles, and Release Agent Particles]
(1) Measuring device: Laser diffraction type particle size measuring device "LA-920" (manufactured by Horiba, Ltd.)
(2) Measurement conditions: Put a sample dispersion in a measurement cell, add distilled water, and measure the volume median particle size ( _D50 ) and volume average particle size at a temperature where the absorbance is in the appropriate range. The CV value is calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution/volume average particle size) x 100

[Solid Content Concentration of Resin Dispersion, Colorant Dispersion, and Release Agent Dispersion]
Using an infrared moisture meter "FD-230" (Kett Electric Laboratory Co., Ltd.), 5 g of the measurement sample is dried under conditions of a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, fluctuation range 0.05%), and the moisture content (mass%) of the dispersion is measured. The solid content concentration is calculated according to the following formula.
Solid content concentration (mass%) = 100 - water (mass%)

[Volume Median Particle Size of Agglomerated 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" (Beckman Coulter, Inc.)
Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.)
Measurement conditions: A sample dispersion is added to 100 mL of the electrolyte to adjust the concentration to a level that allows the particle size of 30,000 particles to be measured in 20 seconds. The 30,000 particles are then measured, and the volume median particle size ( _D50 ) is determined from the particle size distribution.

[Average particle size of external additives]
The average particle size refers to the number-average particle size, and is determined by measuring the particle sizes (average of major and minor diameters) of 500 particles in a scanning electron microscope (SEM) photograph and averaging these by number.

[Volume Median Particle Size ( _D50 ) of Toner]
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" (Beckman Coulter, Inc.)
Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.)
Dispersion: Polyoxyethylene lauryl ether "EMULGEN (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] was dissolved in the electrolyte to adjust the concentration to 5% by mass. Dispersion conditions: 10 mg of a measurement sample was added to 5 mL of the dispersion, and the mixture was dispersed for 1 minute using an ultrasonic disperser (machine name: US-1, manufactured by SND Corporation, output: 80 W). Thereafter, 25 mL of the electrolyte was added, and the mixture was further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration to a level that allows the particle sizes of 30,000 particles to be measured in 20 seconds. The 30,000 particles are then measured, and the volume median particle size ( _D50 ) is determined from the particle size distribution.

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

Resin Production Example 1
The alcohol components, carboxylic acid components other than trimellitic anhydride, PET, esterification catalyst, and cocatalyst shown in Tables 1 to 3 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a downflow condenser with a dehydration tube, a stirrer, and a thermocouple, and the mixture was heated to 235°C under a nitrogen atmosphere, and then polycondensed at 235°C for 6 hours. The temperature was then lowered to 210°C, and trimellitic anhydride shown in Tables 1 to 3 was added, reacted at 210°C for 1 hour, and then further reacted at 210°C under a reduced pressure of 10 kPa until the softening point described in the table was reached, to obtain amorphous polyester resins (resins AH1 to AH8, AH13 to AH16). The physical properties are shown in Tables 1 to 3.

Resin Production Example 2
The alcohol component, carboxylic acid component, PET, esterification catalyst, and cocatalyst shown in Tables 2 and 5 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a downflow condenser with a dehydration tube, a stirrer, and a thermocouple, and the mixture was kept at 180°C for 1 hour under a nitrogen atmosphere, then heated from 180°C to 235°C at a rate of 10°C/h, and polycondensed at 235°C for 5 hours. The temperature was then lowered to 210°C and the reaction was continued under a reduced pressure of 10 kPa until the softening point shown in the table was reached, to obtain amorphous polyester resins (resin AH9, resin AL9). The physical properties are shown in Tables 2 and 5.

Resin Production Example 3
The alcohol component, carboxylic acid component other than trimellitic anhydride, PET, esterification catalyst, and cocatalyst shown in Table 2 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a downflow condenser with a dehydration tube, a stirrer, and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and then polycondensed at 235°C for 10 hours. The temperature was then lowered to 210°C, trimellitic anhydride shown in Table 2 was added, and the mixture was reacted at 210°C for 1 hour, and then further reacted at 210°C under a reduced pressure of 10 kPa until the softening point described in Table 2 was reached, to obtain an amorphous polyester resin (resin AH10). The physical properties are shown in Table 2.

Resin Production Example 4
The alcohol component, carboxylic acid component other than trimellitic anhydride, esterification catalyst, and cocatalyst shown in Table 2 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, a dehydration tube equipped with a fractionating tube through which hot water of 98 ° C. was passed, a stirrer, and a thermocouple, and the mixture was held at 180 ° C. for 1 hour under a nitrogen atmosphere, and then heated from 180 ° C. to 235 ° C. at 10 ° C./h, and then polycondensed at 235 ° C. for 5 hours. Thereafter, the temperature was lowered to 210 ° C., trimellitic anhydride shown in Table 2 was added, and the mixture was reacted at 210 ° C. for 1 hour, and then the reaction was continued at 210 ° C. under a reduced pressure of 10 kPa until the softening point described in Table 2 was reached, to obtain an amorphous polyester resin (resin AH11). The physical properties are shown in Table 2.

Resin Production Example 5
The alcohol component, carboxylic acid component other than trimellitic anhydride, esterification catalyst, and cocatalyst shown in Table 2 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a downflow condenser with a dehydration tube, a stirrer, and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and then polycondensed at 235°C for 6 hours. The temperature was then lowered to 210°C, trimellitic anhydride shown in Table 2 was added, and the mixture was reacted at 210°C for 1 hour, and then further reacted at 210°C under a reduced pressure of 10 kPa until the softening point described in Table 2 was reached, to obtain an amorphous polyester resin (resin AH12). The physical properties are shown in Table 2.

Resin Production Example 6
The alcohol component, carboxylic acid component, PET, esterification catalyst, and cocatalyst shown in Tables 4 to 6 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a downflow condenser with a dehydration tube, a stirrer, and a thermocouple, and the temperature was raised to 235° C. under a nitrogen atmosphere, and polycondensation was carried out at 235° C. for 6 hours. The temperature was then lowered to 210° C., and the reaction was carried out under a reduced pressure of 10 kPa until the softening points shown in Tables 4 to 6 were reached, to obtain amorphous polyester resins (resins AL1 to AL8, AL13 to AL16). The physical properties are shown in Tables 4 to 6.

Resin Production Example 7
The alcohol component, carboxylic acid component, PET, esterification catalyst, and cocatalyst shown in Table 5 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a downflow condenser with a dehydration tube, a stirrer, and a thermocouple, and the temperature was raised to 235° C. under a nitrogen atmosphere, and then polycondensed at 235° C. for 10 hours. The temperature was then lowered to 210° C., and the reaction was continued under a reduced pressure of 10 kPa until the softening point shown in Table 5 was reached, to obtain an amorphous polyester resin (resin AL10). The physical properties are shown in Table 5.

Resin Production Example 8
The alcohol component, carboxylic acid component, esterification catalyst, and cocatalyst shown in Table 5 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, a dehydration tube equipped with a fractionation tube through which hot water of 98 ° C. was passed, a stirrer, and a thermocouple, and the mixture was kept at 180 ° C. for 1 hour under a nitrogen atmosphere, and then heated from 180 ° C. to 235 ° C. at a rate of 10 ° C./h, and then polycondensed at 235 ° C. for 5 hours. The temperature was then lowered to 210 ° C. and the reaction was continued under a reduced pressure of 10 kPa until the softening point shown in Table 5 was reached, to obtain an amorphous polyester resin (resin AL11). The physical properties are shown in Table 5.

Resin Production Example 9
The alcohol component, carboxylic acid component, esterification catalyst, and cocatalyst shown in Table 5 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a downflow condenser with a dehydration tube, a stirrer, and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and then polycondensed at 235°C for 6 hours. The temperature was then lowered to 210°C, and the reaction was continued under a reduced pressure of 10 kPa until the softening point shown in Table 5 was reached, to obtain an amorphous polyester resin (resin AL12). The physical properties are shown in Table 5.

Resin Production Example 10
The alcohol component and carboxylic acid component shown in Table 7 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser with a dehydration tube, and a nitrogen inlet tube, and the temperature was raised to 200° C. over 8 hours in a nitrogen atmosphere in a mantle heater. Then, an esterification catalyst shown in Table 7 was added, and the reaction was carried out at 8.0 kPa until the softening point shown in Table 7 was reached, to obtain a crystalline polyester resin (resin C1). The physical properties are shown in Table 7.

Examples 1 to 6, 8 to 11, 14 to 18, and Comparative Examples 2 and 3 [Melt-kneading method]
100 parts by mass of a binder resin shown in Table 8, 5 parts by mass of a colorant "Toner Yellow HG" (manufactured by Clariant, C.I. Pigment Yellow 180), 3 parts by mass of a release agent "Carnauba Wax C1" (manufactured by Kato Yoko Co., Ltd., melting point: 83°C), and 0.5 parts by mass of a negatively chargeable charge control agent "Bontron E-304" (manufactured by Orient Chemical Industries Co., Ltd.) were mixed in a Henschel mixer.

The resulting mixture was melt-kneaded using a co-rotating twin-screw extruder with a kneading section total length of 1,560 mm, screw diameter of 42 mm, and barrel inner diameter of 43 mm at a screw rotation speed of 200 r/min and barrel set temperature of 100°C to obtain a molten kneaded product. The mixture was fed at a rate of 20 kg/h and the average residence time was approximately 18 seconds.

The resulting molten kneaded product was cooled, coarsely pulverized, pulverized in a jet mill, and classified using an air classifier (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain toner particles having a volume median particle size (D ₅₀ ) of 7.0 μm.

100 parts by weight of the obtained toner particles and 1.0 part by weight of hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, average particle size: 16 nm) and 1.0 part by weight of hydrophobic silica "RY-50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil, average particle size: 40 nm) as external additives were mixed in a Henschel mixer at a rotation speed of 3000 r/min (circumferential speed of 32 m/sec) for 3 minutes to obtain a yellow toner.

Example 7
A yellow toner was obtained in the same manner as in Example 1, except that in Example 1, "Paliotol Yellow D1155" (manufactured by Sun Chemical Co., C.I. Pigment Yellow 185) was used instead of the colorant "Toner Yellow HG" (manufactured by Clariant, C.I. Pigment Yellow 180).

Comparative Example 1
A yellow toner was obtained in the same manner as in Example 1, except that in Example 1, "Toner Yellow 3GP-CT" (Clariant, C.I. Pigment Yellow 155 (total number of -NH- groups and -NH ₂ groups in one molecule = 2, molecular weight = 717, NH group amount = 2.8 mmol/g)) was used instead of the colorant "Toner Yellow HG" (Clariant, C.I. Pigment Yellow 180).

Comparative Example 4
A yellow toner was obtained in the same manner as in Example 1, except that in Example 1, "HANSA Yellow 5GX01" (Clariant, C.I. Pigment Yellow 74 (total number of -NH- groups and -NH ₂ groups in one molecule = 1, molecular weight = 386, NH group amount = 2.6 mmol/g)) was used instead of the colorant "Toner Yellow HG" (Clariant, C.I. Pigment Yellow 180).

Example 12
A yellow toner was obtained in the same manner as in Example 1, except that a continuous two-roll open-roll kneader "Kneedex" (manufactured by Nippon Coke & Engineering Co., Ltd.) was used instead of the same-rotation twin-screw extruder during melt kneading. The continuous two-roll open-roll kneader had an outer diameter of 0.14 m and an effective roll length of 0.8 m, and the operating conditions were a rotation speed of the high-rotation roll (front roll) of 75 r/min (circumferential speed 33 m/min), a rotation speed of the low-rotation roll (rear roll) of 50 r/min (circumferential speed 22 m/min), and a roll gap of 0.1 mm. The heating and cooling medium temperatures in the rolls were set as follows: the temperature of the raw material input side of the high-rotation roll was set to 140°C, and the temperature of the kneaded material discharge side was set to 110°C, and the temperature of the raw material input side of the low-rotation roll was set to 65°C, and the temperature of the kneaded material discharge side was set to 30°C. The supply rate of the raw material mixture was 10 kg/h, and the average residence time was about 5 minutes.

Example 13 [Emulsion aggregation method]
<Preparation of Aqueous Dispersion of Core Resin Particles>
600 g of methyl ethyl ketone was added to a 5-liter container equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube, and 129 g of resin AH1 and 21 g of resin C1 were added at 60 ° C. and dissolved. A 5% by mass aqueous solution of sodium hydroxide was added to the obtained solution so that the degree of neutralization was 60 mol% with respect to the acid value of the resin, and the mixture was stirred for 30 minutes to obtain a mixture. Subsequently, 675 g of deionized water was added over 77 minutes. Next, while stirring at 250 r / min, methyl ethyl ketone was distilled off at a temperature of 50 ° C. or less under reduced pressure, and the solid content concentration of the aqueous dispersion was measured, and the solid content concentration of the aqueous dispersion was adjusted to 20% by mass with deionized water to obtain a core resin dispersion. The volume median particle size (D ₅₀ ) of the resin particles in the dispersion was 200 nm, and the CV value was 24%.

<Preparation of Aqueous Dispersion of Shell Resin Particles>
600 g of methyl ethyl ketone was added to a 5-liter container equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube, and 150 g of resin AL1 was added at 60 ° C. and dissolved. A 5% by mass aqueous solution of sodium hydroxide was added to the obtained solution so that the degree of neutralization was 60 mol% with respect to the acid value of the resin, and the mixture was stirred for 30 minutes to obtain a mixture. Subsequently, 675 g of deionized water was added over 77 minutes. Next, while stirring at 250 r / min, methyl ethyl ketone and a part of the water were distilled off at a temperature of 50 ° C. or less under reduced pressure, and then the solid content concentration of the aqueous dispersion was measured, and the solid content concentration of the aqueous dispersion was adjusted to 20% by mass with deionized water to obtain a shell resin dispersion. The volume median particle size (D ₅₀ ) of the resin particles in the dispersion was 130 nm, and the CV value was 22%.

<Preparation of Colorant Dispersion>
Into a 1-liter beaker, 116.2 g of colorant "Toner Yellow HG" (Clariant, C.I. Pigment Yellow 180), 154.9 g of anionic surfactant "Neopelex (registered trademark) G-15" (Kao Corporation, 15% by mass aqueous solution of sodium dodecylbenzenesulfonate) and 260 g of deionized water were mixed and dispersed using a homogenizer at room temperature for 3 hours, and then deionized water was added so that the solid concentration became 24% by mass, thereby obtaining a colorant dispersion. The volume median particle size (D ₅₀ ) of the colorant particles in the dispersion was 140 nm, and the CV value was 28%.

<Preparation of release agent dispersion>
50 g of Fischer-Tropsch wax (manufactured by Nippon Seiro Co., Ltd., trade name: FNP0090, melting point: 90° C.), 5 g of a cationic surfactant (manufactured by Kao Corporation, trade name: Sanisol B50) and 200 g of deionized water were heated to 95° C., the wax was dispersed using a homogenizer, and then a dispersion treatment was performed using a pressure discharge homogenizer to obtain a release agent dispersion liquid with a solid content concentration of 20 mass %. The volume median particle diameter (D ₅₀ ) of the release agent particles in the dispersion liquid was 550 nm, and the CV value was 26%.

<Preparation of Toner Particles>
In a 3-liter four-neck flask equipped with a reflux condenser, a stirrer, and a thermocouple, 500 g of the core resin dispersion, 36 g of the colorant dispersion, 33 g of the release agent dispersion, and 3.3 g of a 15% by mass aqueous solution of sodium dodecylbenzenesulfonate "Neopelex G-15" (manufactured by Kao Corporation, an anionic surfactant) were mixed at a temperature of 25° C. Next, while stirring the resulting mixture, a solution obtained by dissolving 40 g of ammonium sulfate in 570 g of deionized water and adding a 4.8% by mass aqueous solution of potassium hydroxide to adjust the pH to 8.2 was dropped over 10 minutes at 25° C., and the temperature was then raised to 62° C. over 2 hours, and the temperature was maintained at 62° C. until the volume median particle size (D ₅₀ ) of the aggregated particles reached 7.1 μm, thereby obtaining a dispersion of aggregated particles (I).

While maintaining the temperature of the obtained dispersion of aggregated particles (I) at 62° C., 215 g of the shell resin dispersion was added dropwise at a rate of 0.6 mL/min (0.6 g/min) to obtain a dispersion of aggregated particles (II). The volume median particle size (D ₅₀ ) of the aggregated particles (II) was 7.0 μm.

To the resulting dispersion of aggregated particles (II), an aqueous solution of 20 g of sodium polyoxyethylene lauryl ether sulfate "EMAL E-27C" (Kao Corporation, anionic surfactant, effective concentration 27% by mass), 280 g of deionized water, and 40 g of 0.1 mol/L aqueous sulfuric acid solution was added. The temperature was then raised to 80°C over 1 hour, and the mixture was held at 80°C for 30 minutes, after which 10 g of 0.1 mol/L aqueous sulfuric acid solution was added and the mixture was held at 80°C for a further 15 minutes. Then, 15 g of 0.1 mol/L aqueous sulfuric acid solution was added again, and the mixture was held at 80°C until the circularity reached 0.970, thereby obtaining a dispersion of fused particles (core-shell particles) in which the aggregated particles were fused.

The obtained core-shell particle dispersion was cooled to 30° C., and the solid content was separated by suction filtration of the dispersion, washed with deionized water at 25° C., and suction filtration was performed for 2 hours at 25° C. Thereafter, vacuum drying was performed for 24 hours at 33° C. using a vacuum constant temperature dryer "DRV622DA" (manufactured by ADVANTEC) to obtain toner particles. The volume median particle size (D ₅₀ ) of the obtained toner particles was 7.0 μm, and the circularity was 0.970. The composition ratio (mass ratio) of the binder resin of the obtained toner particles was resin AH1/resin AL1/resin C1=60/30/10.

100 parts by weight of the obtained toner particles and 1.0 part by weight of hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, average particle size: 16 nm) and 1.0 part by weight of hydrophobic silica "RY-50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil, average particle size: 40 nm) as external additives were mixed in a Henschel mixer at a rotation speed of 3000 r/min (circumferential speed of 32 m/sec) for 3 minutes to obtain a yellow toner.

Test example [Smear of printed matter]
The toner was loaded into a copier "AR-505" (product name, manufactured by Sharp Corporation), and the solid image was removed before passing through the fixing machine to obtain a printout in an unfixed state (print area: 2 cm x 12 cm, adhesion amount: 0.5 mg/ ^cm2 ). Furthermore, an unfixed image was printed twice on the same paper to obtain an adhesion amount of 1.5 mg/ ^cm2 . The unfixed image thus obtained was fixed at 150°C and 300 mm/s to obtain a printout.

A stainless steel weight measuring 3 cm in length, 3 cm in width, and 6.5 cm in height, and weighing 500 g, was placed on the resulting print and moved back and forth over the print at a speed of 0.5 m/s. One back and forth was counted as one pass, with a maximum of 50 passes. The number of times that black band-like toner deposits appeared in the non-printed areas was visually confirmed, and smearing was evaluated. The results are shown in Table 8. A higher number of passes indicates better smearing. In the table, ">50" indicates that no toner deposits were observed even after 50 passes.

The above results show that the toners of Examples 1 to 18 have good smear properties compared to the toners of Comparative Examples 1 and 4, which contain organic yellow pigments with a low NH group content, and the toners of Comparative Examples 2 and 3, which do not use PET. In particular, Comparative Example 2 shows that using ethylene glycol and terephthalic acid, which are monomer components of PET, is ineffective, and that it is important to use PET.

The toner for developing electrostatic images of the present invention is suitable for use in developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, etc.

Claims (11)

The toner for developing electrostatic images contains a binder resin and a colorant, the binder resin containing an amorphous polyester resin A which is a polycondensation product of polyethylene terephthalate, an alcohol component, and a carboxylic acid component, and the colorant containing an organic yellow pigment having an NH group amount of 4.0 mmol/g or more and 15.0 mmol/g or less, where the NH group amount is a value obtained by dividing the total number of -NH- groups and -NH2 _groups in one molecule by the molecular weight. The toner for developing electrostatic images according to claim 1, wherein the content of polyethylene terephthalate is 5 mol % or more and 75 mol % or less of the total amount of the alcohol component, the carboxylic acid component, and the polyethylene terephthalate, with terephthalic acid-ethylene glycol units being 1 mol. The toner for developing electrostatic images according to claim 1, wherein the content of polyethylene terephthalate is 10 mol % or more and 50 mol % or less of the total amount of the alcohol component, the carboxylic acid component, and the polyethylene terephthalate, with 1 mol of terephthalic acid-ethylene glycol unit. The toner for developing electrostatic images according to any one of claims 1 to 3, wherein the IV value of the polyethylene terephthalate is 0.40 or more and 0.85 or less. The toner for developing electrostatic images according to any one of claims 1 to 4, wherein the organic yellow pigment is at least one selected from the group consisting of benzimidazolone pigments, isoindoline pigments, and condensed disazo pigments. The toner for developing electrostatic images according to any one of claims 1 to 4, wherein the organic yellow pigment is at least one selected from C.I. Pigment Yellow 180 and C.I. Pigment Yellow 185. The toner for developing electrostatic images according to any one of claims 1 to 6, wherein the ester group concentration of the amorphous polyester resin A is 3.5 mmol/g or more and 12.0 mmol/g or less. The toner for developing electrostatic images according to any one of claims 1 to 7, wherein the content of the organic yellow pigment is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the amorphous polyester resin A. The toner for developing electrostatic images according to any one of claims 1 to 8, wherein the binder resin further contains crystalline polyester resin C. The toner for developing electrostatic images according to any one of claims 1 to 9, wherein the amorphous polyester resin A contains resins with different softening points, the difference between which is 10°C or more. The method for producing a toner for developing electrostatic images according to any one of claims 1 to 10, comprising a step of melting and kneading at least the binder resin and the colorant, and a step of pulverizing the resulting kneaded product.