JP7851364B2 - Method for manufacturing toner for dry developing - Google Patents

Description

This invention relates to a method for manufacturing a dry developing toner used in the dry developing of latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like.

In the field of electrophotography, with the advancement of electrophotographic systems, there is a growing need for the development of electrostatic image developing toners that produce high-gloss images to meet the demands for even higher image quality.

On the other hand, a polyester resin using polyethylene terephthalate along with the raw material monomer is being considered for use as a binder resin in toners for electrostatic image development.

Patent Document 1 discloses a liquid developer containing toner particles containing a binder resin and a colorant, a dispersant, and an insulating liquid, wherein the binder resin is a polyester resin which is a polycondensate of raw materials containing an alcohol component, a carboxylic acid component, and polyethylene terephthalate, the acid value of the polyester resin is 15 mg KOH/g or more and 70 mg KOH/g or less, and the amine value of the dispersant is 50 mg KOH/g or more and 300 mg KOH/g or less.

Patent Document 2 discloses a liquid developer in which toner particles containing a binder resin and a colorant are dispersed in an insulating liquid, wherein the binder resin contains a polyester resin, the insulating liquid contains 50% by mass or more of saturated aliphatic hydrocarbons, the initial boiling point temperature of the insulating liquid is 190°C to 240°C, and the difference between the initial boiling point and the dry point is 15°C or less. It also states that polyethylene terephthalate may be used as part of the alcohol and carboxylic acid components.

Patent Document 3 discloses a toner binder resin composition containing an amorphous resin and a crystalline resin, wherein the amorphous resin comprises polyester resin A, which is a polycondensate of an alcohol component containing an aliphatic diol having a hydroxyl group bonded to a secondary carbon atom, a carboxylic acid component, and polyethylene terephthalate; and the crystalline resin comprises polyester resin C, which is a polycondensate of an alcohol component containing 50 mol% to 100 mol% of ethylene glycol and a carboxylic acid component; and the mass ratio of the amorphous resin to the crystalline resin (amorphous resin/crystalline resin) is 65/35 to 95/5.

Japanese Patent Publication No. 2021-56477 Japanese Patent Publication No. 2020-86376 Japanese Patent Publication No. 2019-66536

Glossiness is inversely related to hot offset resistance, one of the main fixing performance characteristics. Therefore, a toner that achieves both is required. However, the liquid developers described in Patent Documents 1 and 2 fix the image by drying the insulating liquid with heat after coating with a bar coater, thus eliminating the problem of hot offset. Furthermore, Patent Document 3 does not consider the balance between glossiness and hot offset resistance, leaving room for improvement.

This invention relates to a method for manufacturing a dry-process toner that achieves both gloss and resistance to hot offset.

The present invention
[1] A method for producing a dry developer toner containing amorphous polyester resin A, wherein the amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, and the method comprises the steps of: melt-kneading a mixture containing the amorphous polyester resin A using an open-roll twin-screw kneader; crushing and classifying the resulting kneaded material to obtain toner matrix particles; and mixing the obtained toner matrix particles with an external additive; and [2] A method for fixing a toner, wherein the dry developer toner obtained by the method described in [1] is fixed to a medium by heat and pressure.

The method of the present invention yields a dry-process toner that exhibits excellent gloss and resistance to hot offset.

The present invention's method for manufacturing electrostatic image developing toner is characterized by the use of an amorphous polyester resin (amorphous polyester resin A) made from polyethylene terephthalate (PET), and the use of an open-roll twin-screw kneader for melting and kneading the raw materials. While the reason why the electrostatic image developing toner obtained by the present invention exhibits excellent hot-off resistance and gloss is not entirely clear, it is presumed to be as follows.

If the elasticity of the toner is increased to improve hot offset resistance, the toner will not spread easily during fixing, resulting in a decrease in gloss. On the other hand, if the elasticity of the toner is decreased to improve the spreadability of the toner to improve gloss, offset will occur at high temperatures. Therefore, controlling the elasticity of the toner is necessary to achieve both hot offset resistance and gloss.
When manufacturing toner, using a twin-screw extruder for melting and mixing the raw materials results in low mixing strength, making it difficult to break the resin's molecular chains. This leaves a large amount of high-elasticity components, resulting in a toner with excellent hot-off resistance but poor gloss. Conversely, reducing the amount of high-elasticity components by lowering the molecular weight reduces hot-off resistance, making it difficult to control the physical properties. On the other hand, using an open-roll twin-screw mixer with high mixing strength results in lower elasticity because the resin molecules are broken. As a result, the toner has excellent gloss but poor hot-off resistance.
In this invention, by using an amorphous polyester resin made of PET as the amorphous resin, it was found that the resulting toner maintains hot offset resistance while exhibiting excellent gloss, even when using an open-roll twin-screw kneader with high kneading strength. In the polycondensation reaction between the alcohol component, the carboxylic acid component, and PET, PET is incorporated into the polyester resin chain by transesterification while undergoing depolymerization, but it is not completely randomized, and units that can be called PET segments exist in the resulting resin. As a result, perhaps because of the strong interaction between these PET segments of a certain length, molecular chain severance is suppressed even when using an open-roll twin-screw kneader with high kneading strength, and not all of the resin becomes low-elastic, with a moderate amount of high-elasticity components remaining, so it is thought that the resulting toner is excellent in both hot offset resistance and gloss.

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

Regarding the alcohol component, from the viewpoint of low-temperature fixation, formula (I):

(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, each being 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.)
Compounds represented by formula (I) are preferred. Examples of alkylene oxide adducts of bisphenol A represented by formula (I) include polyoxypropylene adducts of 2,2-bis(4-hydroxyphenyl)propane and polyoxyethylene adducts of 2,2-bis(4-hydroxyphenyl)propane. It is preferable to use one or more of these.

The content of the bisphenol A alkylene oxide adduct represented by formula (I) is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol% of the alcohol component. However, the ethylene glycol units of PET are not included in the alcohol component as used herein.

Other alcoholic components include aliphatic diols and trivalent or higher alcohols.

Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol, 1,3-butanediol, and neopentyl glycol.

Examples of alcohols with a hydride of 3 or higher include glycerin, trimethylolpropane, and pentaerythritol.

From the viewpoint of hot offset resistance, the carboxylic acid component preferably includes an aromatic dicarboxylic acid compound.

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

The content of aromatic dicarboxylic acid compounds is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more, and 100 mol% or less, of the carboxylic acid component. If the carboxylic acid component includes trivalent or higher carboxylic acid compounds, the content is preferably 90 mol% or less, and more preferably 85 mol% or less. However, the terephthalic acid units contained in PET are not included in the carboxylic acid component as used herein.

Other carboxylic acid components include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, aliphatic dicarboxylic acids such as glutaric acid, adipic acid, and sebacic acid, trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

From the viewpoint of adjusting the softening point, the alcohol component and/or carboxylic acid component of amorphous polyester resin A may use raw material monomers of trivalent or higher valency. In that case, from the viewpoint of resistance to hot offset, it is preferable that a polyvalent carboxylic acid compound of trivalent or higher valency, preferably a trimellitic acid compound, and more preferably trimellitic anhydride, be used. The content of the raw material monomer of trivalent or higher valency is preferably 3 mol% or more, more preferably 5 mol% or more, and preferably 30 mol% or less, and more preferably 20 mol% or less, based on the total amount of the alcohol component, carboxylic acid component, and PET.

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

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

PET is produced through a polycondensation reaction between an alcohol component and a carboxylic acid component, and/or through the depolymerization of a portion of PET. The resulting ethylene glycol and terephthalic acid are then used as raw material monomers in the polycondensation reaction and incorporated into the polyester resin. PET is considered an equimolar polycondensate of ethylene glycol and terephthalic acid, with ethylene glycol and terephthalic acid being considered as the alcohol component and carboxylic acid component, respectively.

The PET can be either new virgin PET or recycled PET.
Recycled PET refers to PET obtained by collecting used PET, washing it as needed, separating it from other materials, crushing it, decomposing the crushed material into monomer units through depolymerization, and then resynthesizing it using these monomers as raw materials.

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

From the above viewpoint, the IV value of PET is preferably 0.40 or higher, more preferably 0.45 or higher, even more preferably 0.50 or higher, and still more preferably 0.55 or higher. Furthermore, from the viewpoint of low-temperature fixability and uniform depolymerization, it is preferably 0.80 or lower, more preferably 0.75 or lower, even more preferably 0.70 or lower, and still more preferably 0.65 or lower. The IV value is the intrinsic viscosity and serves as an indicator of molecular weight. The IV value of PET can be adjusted by the polycondensation time, etc.

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

The content of low-IV PET 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, of the total amount of PET subjected to polycondensation.

The PET content is 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, and even more preferably 60 mol% or less, from the viewpoint of hot offset resistance, relative to the total amount of alcohol component, carboxylic acid component, and PET.
If amorphous polyester resin A consists of two or more resins, the weighted average value of the PET content of each resin shall be used as the PET content of amorphous polyester resin A.

Furthermore, when amorphous polyester resin A consists of resin AH and resin AL (described later), it is preferable that resin AH has a higher PET content than resin AL from the viewpoint of hot offset resistance.

The PET content in resin AH is preferably 4 mol% or more, more preferably 20 mol% or more, and even more preferably 40 mol% or more, of the total amount of alcohol component, carboxylic acid component, and PET, from the viewpoint of hot offset resistance, and preferably 80 mol% or less, more preferably 75 mol% or less, and even more preferably 65 mol% or less, from the viewpoint of gloss.
Furthermore, the PET content in the resin AL is preferably 4 mol% or more, more preferably 15 mol% or more, and even more preferably 25 mol% or more, of the total amount of alcohol component, carboxylic acid component, and PET, from the viewpoint of hot offset resistance, and preferably 70 mol% or less, more preferably 55 mol% or less, and even more preferably 45 mol% or less, from the viewpoint of gloss.
Since PET is a polycondensate of ethylene glycol, terephthalic acid, dimethyl terephthalate, etc., the terephthalic acid-ethylene glycol unit (Mw: 192) is considered 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.

The equivalent ratio (COOH group/OH group) of the carboxylic acid component (including terephthalic acid units in PET) to the alcohol component (including ethylene glycol units in PET) 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.

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 optionally in the presence of a 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.

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, based on 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, based on 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.

In this invention, the polyester resin may be a modified polyester resin to the extent that its properties are not substantially impaired. Examples of modified polyester resins include those 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 the polyester resin with a polyisocyanate compound are preferred.

The softening point of amorphous polyester resin A is preferably 70°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower, from the viewpoint of hot offset resistance and gloss.

The crystallinity of a resin is expressed by a crystallinity index, which is defined by the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, i.e., the value of [softening point / maximum endothermic peak temperature].
The amorphous resin is one in which no endothermic peak is observed, or, if observed, a resin with a crystallinity index greater than 1.4, preferably greater than 1.5, more preferably 1.6 or higher, or less than 0.6, preferably 0.5 or lower.
On the other hand, the crystalline resin is a resin having a crystallinity index of 0.6 or higher, preferably 0.7 or higher, more preferably 0.9 or higher, and 1.4 or lower, preferably 1.2 or lower, more preferably 1.1 or lower.
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.

Furthermore, from the viewpoint of low-temperature fixability and fixation width, amorphous polyester resin A preferably contains two amorphous polyester resins with different softening points. The difference in softening points between the two resins is preferably 10°C or higher, more preferably 20°C or higher, and preferably 60°C or lower, more preferably 40°C or lower.

The softening point of the amorphous polyester resin (resin AH) with a high softening point is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower, from the viewpoint of hot offset resistance and gloss.

Furthermore, the softening point of the amorphous polyester resin (resin AL) with a lower softening point is preferably 70°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and preferably 130°C or lower, more preferably 125°C or lower, and even more preferably 120°C or lower, from the viewpoint of hot offset resistance and gloss.

The mass ratio of resin AH to resin AL (resin AH/resin AL) is preferably 30/70 or higher, more preferably 50/50 or higher, even more preferably 55/45 or higher, even more preferably 60/40 or higher, and preferably 90/10 or lower, more preferably 80/20 or lower, and even more preferably 75/25 or lower.

The glass transition temperature of amorphous polyester resin A is preferably 40°C or higher, more preferably 50°C or higher, and more preferably 80°C or lower, and more preferably 70°C or lower, from the viewpoint of hot offset resistance and gloss.

The acid value of amorphous polyester resin A is preferably 1 mg KOH/g or higher, more preferably 3 mg KOH/g or higher, and more preferably 20 mg KOH/g or lower, and more preferably 18 mg KOH/g or lower, from the viewpoint of hot offset resistance and gloss.

In the toner, amorphous polyester resin A is included as a binder resin.

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

The content of amorphous polyester resin A 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, in the binder resin.

Furthermore, the binder resin content 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 preferably less than 100% by mass, more preferably 98% by mass or less, and even more preferably 95% by mass or less.

In addition to binder resins, additives such as colorants, release agents, charge control agents, magnetic powders, flow improvers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, and cleaning properties enhancers may also be used as raw materials for toner.

As colorants, dyes, pigments, magnetic materials, etc., used as colorants for toners can be used. Examples include carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment red 122, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, etc. In this invention, the toner may be either black toner or color toner.

From the viewpoint of improving the toner's image density and low-temperature fixability, the amount of colorant used is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the binder resin.

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, and fatty acid metal salts. These can be used individually or in combination of two or more.

The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of the toner's resistance to hot offset, and 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 fixation.

The amount of release agent used 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, per 100 parts by mass of binder resin, from the viewpoint of toner's low-temperature fixation and offset resistance, as well as dispersibility in the binder resin. Furthermore, it 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, Ltd.); triphenylmethane-based dyes containing a tertiary amine as a side chain; and 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.).

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, and organometallic compounds.

From the viewpoint of the toner's charge stability, the amount of charge control agent used 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.

In this invention, toner is manufactured by a method comprising the steps of: melt-kneading a mixture containing amorphous polyester resin A and, optionally, additives such as a colorant, mold release agent, and charge control agent, using an open-roll twin-screw kneader (melt-kneading step); crushing and classifying the resulting mixture to obtain toner base particles (crushing and classification step); and mixing the obtained toner base particles with external additives (external additive step).

The mixture to be subjected to melting and kneading may be kneaded all at once or in portions, but it is preferable to mix it beforehand in a mixer such as a Henschel mixer or ball mill before supplying it to an open-roll type kneader.

An open-roll twin-screw mixer is a machine equipped with two rolls, where the mixing section is not sealed but open (a twin-roll open-roll mixer), allowing for easy dissipation of the mixing heat generated during melt mixing. The open-roll twin-screw mixer used in this invention is equipped with a raw material supply port and a mixed material discharge port located along the axial direction of the rolls. From the viewpoint of production efficiency, a continuous open-roll twin-screw mixer is preferable.

The open-roll twin-shaft kneader used in this invention is preferably equipped with two rolls with different peripheral speeds, namely a roll with a high peripheral speed (high-speed roll) and a roll with a low peripheral speed (low-speed roll). In this invention, from the viewpoint of dispersibility of the kneaded material, it is preferable that the high-speed roll functions as a heating roll and the low-speed roll functions as a cooling roll; that is, it is preferable that the set temperature of the high-speed roll is higher than the set temperature of the low-speed roll. If the set temperatures of the rolls differ between the raw material input side and the kneaded material discharge side, it is preferable that the set temperature of the high-speed roll is higher than the set temperature of the low-speed roll at least on the raw material input side, and more preferably that the set temperature of the high-speed roll is higher than the set temperature of the low-speed roll on both the raw material input side and the kneaded material discharge side.

The temperature of the roll can be adjusted, for example, by the temperature of the heat transfer medium passed through the roll. Each roll may also have its interior divided into two or more sections through which heat transfer mediums with different temperatures are passed.

The temperature on the raw material input side of the high-speed rolls is preferably 80°C or higher, more preferably 100°C or higher, even more preferably 120°C or higher, and preferably 160°C or lower, more preferably 150°C or lower, from the viewpoint of reducing mechanical force during melting and kneading and suppressing heat generation. Similarly, the temperature on the raw material input side of the low-speed rolls is preferably 25°C or higher, more preferably 40°C or higher, and preferably 80°C or lower, more preferably 70°C or lower.

In both high-speed and low-speed rolls, it is preferable that the temperature on the raw material input side is higher than that on the mixed material discharge side. The temperature difference between the raw material input side and the mixed material discharge side is preferably 20°C or higher, more preferably 30°C or higher, and more preferably 60°C or lower, more preferably 50°C or lower, from the viewpoint of preventing the mixed material from detaching from the rolls and reducing mechanical force during melt-kneading to suppress heat generation.

The temperature on the raw material input side of the high-speed and low-speed rolls refers to the set temperature at the raw material input end, while the temperature on the mixed material discharge side refers to the set temperature at the mixed material discharge end.

The peripheral speed of the high-speed roll is preferably 2 m/min or more, more preferably 10 m/min or more, even more preferably 25 m/min or more, and preferably 100 m/min or less, more preferably 75 m/min or less, and even more preferably 50 m/min or less, from the viewpoint of reducing mechanical force during mixing and suppressing heat generation. The peripheral speed of the low-speed roll is preferably 1 m/min or more, more preferably 5 m/min or more, even more preferably 15 m/min or more, and preferably 90 m/min or less, more preferably 60 m/min or less, and even more preferably 30 m/min or less, from the same viewpoint. Furthermore, the ratio of the peripheral speeds of the two rolls (low-speed roll/high-speed roll) is preferably 1/10 or more, more preferably 3/10 or more, and preferably 9.9/10 or less, and even more preferably 8/10 or less.

Furthermore, there are no particular limitations on the structure, size, or material of each roll. The roll surface has grooves used for mixing, and these grooves can be linear, spiral, wavy, or uneven.

After melt-kneading, it is preferable to cool the mixture appropriately until it reaches a hardness suitable for pulverization, and then perform a pulverization and classification process to obtain toner base particles. Here, cooling refers to cooling the mixture to a temperature between 0°C and 50°C, or to a temperature below the glass transition temperature of the binder resin in the mixture.

In grinding a compound, the compound may be ground to the desired particle size in one go or in stages. However, from the viewpoint of efficient and more uniform grinding, it is preferable to perform the grinding in two stages: coarse grinding and fine grinding.

Examples of grinders used for coarse grinding include hammer mills, cutter mills, atomizers, and Rotoplexes.

For coarse grinding, it is preferable to grind until the maximum diameter is 3 mm or less. For example, a pulverized material with a maximum diameter of 3 mm or less can be obtained by coarsely grinding the kneaded material until the particle size is approximately 0.05 mm to 3 mm, then passing it through a sieve with a mesh size of 3 mm, and obtaining the pulverized material that passes through the sieve.

Examples of grinders used for fine grinding include fluidized bed jet mills, impact plate jet mills, and other types of jet mills, as well as mechanical mills.

The degree of fine grinding should preferably be adjusted as appropriate according to the desired toner particle size.

Examples of classifiers used for classification include air-flow classifiers, inertial classifiers, and sieve classifiers. During the classification process, any pulverized material that is removed due to insufficient pulverization may be subjected to the pulverization process again, and the pulverization and classification processes may be repeated as needed.

The median volume particle size (D ₅₀ ) of the toner mother particles obtained by the grinding and classification process 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 median volume particle size (D ₅₀ ) means the particle size at which the cumulative volume frequency calculated by volume fraction accounts for 50% when calculated from the smallest particle size.

Examples of external additives used in the external additive process 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. Two or more types may be used in combination. Among these, silica is preferred, and from the viewpoint of toner transferability, hydrophobic silica that has undergone hydrophobic treatment is more preferred.

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.

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.

The mixing of toner base particles and 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 toner's electrostatic properties, fluidity, and transferability, the amount of external additive used 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 matrix particles.

The toner obtained by the method of the present invention is used in dry development and can be used as a one-component developing toner or as a two-component developing toner mixed with a carrier, respectively, in image forming apparatuses using either a one-component or two-component developing system.

Furthermore, the toner obtained by the method of the present invention can be used in a fixing method that involves fixing the toner to a medium using heat and pressure, thereby achieving both glossiness and resistance to hot offset, thus realizing the effects of the present invention.

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.

[PET IV value]
The phenol/tetrachloroethane is dissolved at a concentration of 4 g/L in a mixed solvent of 60/40 (mass ratio), and the concentration is measured using an Ubbelohde viscometer and calculated from the following formula.
IV=(-1+√(1+4kη))/(2kC)
[In the formula, k = 0.33, C = 0.004 g/mL, and η = ( _t1 / _t0 ) - 1 ( _t0 : number of seconds for the solvent to fall, _t1 : number of seconds for the sample solution to fall).]

[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.

[Maximum peak temperature of endothermic resin]
Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 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.

[Glass transition temperature of resins]
Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 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.

[Acid value of resins]
The measurement will be performed according to the method of JIS K0070:1992. However, the measurement solvent will be changed from the ethanol and ether mixture specified in JIS K0070:1992 to an acetone and toluene mixture (acetone:toluene = 1:1 (volume ratio)).

[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 endothermic peak temperature is defined as the melting point.

[Volume-intermediate particle size of toner matrix particles (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 a concentration of 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: 80 W). Then, add 25 mL of the 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 median particle size (D ₅₀ ) is determined from the particle size distribution.

[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 from scanning electron microscope (SEM) images and using the number-average value of these measurements.

Production Example 1 of Alkenyl Succinic Anhydride
(1) Using propylene tetramer (manufactured by Nippon Oil Corporation, trade name: "Light Tetramer"), alkylene compound (a) was obtained by fractional distillation under heating conditions of 183 to 208°C. The obtained alkylene compound (a) had 40 peaks in gas chromatography-mass spectrometry, as described later. The distribution of the alkylene compound was measured according to the analysis of alkylene compound A by mass spectrometry gas chromatography described in _Japanese Patent Application Publication No. 2014-013384 _, and _{was C9H18} : 0.5 mass% _{, C10H20} : 4 mass%, _C11H22 : 20 mass%, _C12H24 : _{66 mass%, C13H26: 9 mass%, C14H28 : 0.5 mass} % (6 peaks corresponding to alkylene compounds with 9 to 14 carbon atoms).

(2) 542.4 g of alkylene compound (a), 157.2 g of maleic anhydride, 0.4 g of the antioxidant "Cherex-O" (manufactured by SC Organic Chemicals Co., Ltd., Triisooctyl phosphorite), and 0.1 g of butyl hydroquinone as a polymerization inhibitor were charged into a 1 L autoclave manufactured by Nitto High Pressure Co., Ltd. Pressurized nitrogen purging (0.2 MPaG) was repeated three times. After stirring was started at 60°C, the temperature was raised to 230°C over 1 hour and the reaction was carried out for 6 hours. The pressure at the reaction temperature was 0.3 MPaG. After the reaction was complete, it was cooled to 80°C and returned to atmospheric pressure (101.3 kPa) and transferred to a 1 L four-necked flask. The temperature was raised to 180°C while stirring, and the remaining alkylene compound was removed by distillation at 1.3 kPa over 1 hour. Subsequently, the mixture was cooled to room temperature (25°C) and then returned to atmospheric pressure (101.3 kPa) to obtain 406.1 g of the target product, alkenyl succinic anhydride A. The average molecular weight of alkenyl succinic anhydride A, calculated from its acid value, was 268.

Resin manufacturing example 1
The alcohol components, carboxylic acid components other than trimellitic anhydride, PET, esterification catalyst, and co-catalyst shown in Tables 1-3 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, stirrer, and thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 210°C, trimellitic anhydride shown in Tables 1-3 was added, and the mixture was reacted at 210°C for 1 hour. The reaction was then carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Tables 1-3 was reached to obtain amorphous polyester resins (resins AH1-AH4, AH8, AH12-AH15). The physical properties are shown in Tables 1-3.

Resin manufacturing example 2
The alcohol component, PET, esterification catalyst, and co-catalyst shown in Table 1 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, stirrer, and thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 210°C, trimellitic anhydride shown in Table 1 was added, and the mixture was reacted at 210°C for 1 hour. The reaction was then carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, yielding an amorphous polyester resin (resin AH5). The physical properties are shown in Table 1.

Resin manufacturing example 3
The alcohol component, carboxylic acid component, PET, esterification catalyst, and co-catalyst shown in Tables 1, 2, 4, and 5 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, stirrer, and thermocouple. Under a nitrogen atmosphere, the mixture was kept warm at 180°C for 1 hour, then the temperature was increased from 180°C to 235°C at a rate of 10°C/h, and polycondensation was carried out at 235°C for 5 hours. After that, the temperature was reduced to 210°C, and the reaction was carried out under reduced pressure of 10 kPa until the softening point shown in Tables 1, 2, 4, and 5 was reached to obtain amorphous polyester resins (resins AH6-AH7, resins AL6-AL7). The physical properties are shown in Tables 1, 2, 4, and 5.

Resin manufacturing example 4
The alcohol components, PET, esterification catalyst, and co-catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, stirrer, and thermocouple. Under a nitrogen atmosphere, the temperature was raised to 235°C, and polycondensation was carried out at 235°C for 6 hours. After that, the temperature was lowered to 180°C, and trimellitic anhydride, fumaric acid, and polymerization inhibitor shown in Table 2 were added. The reaction was carried out at 180°C for 1 hour, then the temperature was raised from 180°C to 210°C at a rate of 10°C/h, and polycondensation was carried out at 210°C for another 1 hour. After that, the reaction was carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, yielding amorphous polyester resin (resin AH9). The physical properties are shown in Table 2.

Resin manufacturing example 5
The alcohol components, carboxylic acid components other than trimellitic anhydride, esterification catalyst, and co-catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, stirrer, and thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 210°C, trimellitic anhydride as shown in Table 2 was added, and the mixture was reacted at 210°C for 1 hour. The reaction was then carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, yielding an amorphous polyester resin (resin AH10). The physical properties are shown in Table 2.

Resin manufacturing example 6
The alcohol components, carboxylic acid components other than trimellitic anhydride, esterification catalyst, and co-catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydration tube fitted with a fractionation tube through which 98°C hot water was passed, a stirrer, and a thermocouple. Under a nitrogen atmosphere, the mixture was held at 180°C for 1 hour, then the temperature was increased from 180°C to 230°C at a rate of 10°C/h, and polycondensation was carried out at 230°C for 5 hours. After that, the mixture was cooled to 210°C, trimellitic anhydride as shown in Table 2 was added, and the mixture was held at 210°C for 1 hour. The reaction was then carried out under reduced pressure of 10 kPa until the softening point shown in Table 2 was reached to obtain amorphous polyester resin (resin AH11). The physical properties are shown in Table 2.

Resin manufacturing example 7
The alcohol component, carboxylic acid component, PET, esterification catalyst, and co-catalyst shown in Tables 4-6 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, stirrer, and thermocouple. Under a nitrogen atmosphere, the temperature was raised to 235°C, and polycondensation was carried out at 235°C for 6 hours. After that, the temperature was lowered to 210°C, and the reaction was carried out under reduced pressure of 10 kPa until the softening point shown in Tables 4-6 was reached to obtain amorphous polyester resins (resins AL1-AL5, AL8, AL12-AL15). The physical properties are shown in Tables 4-6.

Resin manufacturing example 8
The alcohol component, carboxylic acid component other than fumaric acid, PET, esterification catalyst, and co-catalyst shown in Table 5 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, stirrer, and thermocouple. Under a nitrogen atmosphere, the temperature was raised to 235°C, and polycondensation was carried out at 235°C for 6 hours. After that, the temperature was lowered to 180°C, and the fumaric acid and polymerization inhibitor shown in Table 5 were added. The reaction was carried out at 180°C for 1 hour, then the temperature was raised from 180°C to 210°C at a rate of 10°C/h, and polycondensation was carried out at 210°C for another 1 hour. After that, the reaction was carried out at 210°C under a reduced pressure of 10 kPa until the softening point shown in Table 5 was reached to obtain amorphous polyester resin (resin AL9). The physical properties are shown in Table 5.

Resin manufacturing example 9
The alcohol component, carboxylic acid component, esterification catalyst, and co-catalyst shown in Table 5 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, stirrer, and thermocouple. Under a nitrogen atmosphere, the temperature was raised to 235°C, and polycondensation was carried out at 235°C for 6 hours. After that, the temperature was lowered to 210°C, and the reaction was carried out under reduced pressure of 10 kPa until the softening point shown in Table 5 was reached to obtain amorphous polyester resin (resin AL10). The physical properties are shown in Table 5.

Resin manufacturing example 10
The alcohol component, carboxylic acid component, esterification catalyst, and co-catalyst shown in Table 5 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydration tube fitted with a fractionation tube through which 98°C hot water was passed, a stirrer, and a thermocouple. Under a nitrogen atmosphere, the mixture was held at 180°C for 1 hour, then the temperature was increased from 180°C to 230°C at a rate of 10°C/h, and polycondensation was carried out at 230°C for 5 hours. After that, the mixture was cooled to 210°C and the reaction was carried out under 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.

Examples 1 to 15 and Comparative Examples 2 to 3 (Examples 3, 4 , 10, and 11 are for reference only)
100 parts by mass of the binder resin shown in Table 7, 5 parts by mass of the coloring agent "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (P.B. 15:3)), 3 parts by mass of the release agent "Carnauba Wax C1" (manufactured by Kato Yoko Co., Ltd., melting point: 83°C), 3 parts by mass of the release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 75°C), and 0.5 parts by mass of the charge control agent "Bontron E-304" (manufactured by Orient Chemical Industry Co., Ltd.) were mixed in a Henschel mixer.

The obtained raw material mixture was supplied via a table feeder to a continuous open-roll twin-shaft mixer, "Nidex" (manufactured by Nippon Coke Industries Co., Ltd.), for melt-mixing to obtain a compound. The continuous open-roll twin-shaft mixer used had a roll outer diameter of 0.14 m and an effective roll length of 0.8 m. The operating conditions were: high-speed roll (front roll) rotation speed of 75 r/min (peripheral speed 33 m/min), low-speed roll (rear roll) rotation speed of 50 r/min (peripheral speed 22 m/min), and roll gap of 0.1 mm. The heating and cooling media temperatures within the rolls were set to 150°C on the raw material input side and 110°C on the compound discharge side of the high-speed roll, and 65°C on the raw material input side and 30°C on the compound 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.

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. The obtained coarsely ground material was finely ground using an I-2 type jet pulverizer (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) and classified using an air-flow classifier to obtain toner mother particles with a median volume particle size ( _D50 ) of 7.0 μm.

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

Comparative Example 1
Toner was obtained in the same manner as in Example 1, except that a twin-screw extruder "PCM-30" (manufactured by Ikegai Co., Ltd.) was used to melt-knead the raw material mixture instead of a continuous open-roll twin-screw kneader. 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 supply rate of 10 kg/h.

Test Example 1 [Toner's Hot Offset Resistance]
Toner was loaded into a modified fuser unit of a Sharp AR-505 copier, allowing for external fixing, and an unfixed printout was obtained (print area: 2 cm x 12 cm, adhesion amount: 0.5 mg/ ^cm² ). Subsequently, using a fuser unit adjusted to a total fixing pressure of 40 kgf (fixing speed 300 mm/sec), the fixing test of the unfixed printout was performed at each temperature while the temperature of the fuser roll was gradually increased from 120°C to 200°C in 5°C increments. The fixing paper used was "CopyBond SF-70NA" (Sharp Corporation, 75 g/ ^m² ).
The resulting printed images were visually inspected, and the temperature at which hot offset occurs was identified as the hot offset resistance. The results are shown in Table 7. A higher temperature at which hot offset occurs is preferable. In the table, ">200" indicates that no hot offset occurred even at 200°C.

Test Example 2 [Glossiness of Printed Materials]
A toner was installed in a Sharp AR-505 copier (product name, manufactured by Sharp Corporation), and an image was printed using J-paper (product name, manufactured by Fujifilm Business Innovation Co., Ltd.) without fixing the toner (print area: 2 cm x 12 cm, amount of toner: 0.5 mg/ ^cm² ). The fuser of the copier was removed and fixed to the paper at 160°C and 400 mm/sec using an external fuser. Cardboard was placed under the image, and the glossiness was measured using a gloss meter (Horiba Ltd., product name: "IG-330") under 60° light exposure conditions. The results are shown in Table 7. A higher value indicates higher glossiness.

From the above results, it can be seen that in Examples 1 to 15, toners that achieve both hot offset resistance and gloss can be obtained. Comparing Example 10 and Example 11, it can be seen that when using amorphous polyester resins with different softening points, using a larger amount of PET in the resin with a high softening point rather than the resin with a low softening point further improves hot offset resistance.
In contrast, Comparative Example 1, which used a twin-screw extruder for melt mixing, lacked gloss, and Comparative Example 2, which used an amorphous polyester resin without PET, and Comparative Example 3, which used ethylene glycol and terephthalic acid, which are monomer components of PET, instead of PET, showed a particularly significant decrease in hot offset resistance.

The dry-process toner obtained by the method of the present invention is suitably used for dry-process development of latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like.

Claims (4)

A method for producing a dry-process toner containing amorphous polyester resin A, wherein the amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, and the amorphous polyester resin A consists of two amorphous polyester resins with different softening points, the amorphous polyester resin with a higher softening point has a higher polyethylene terephthalate content than the amorphous polyester resin with a lower softening point, and the polyethylene terephthalate content in the amorphous polyester resin with a higher softening point is 56 mol% or more and 80 mol% or less, and the one with the lower softening point A method for producing toner for dry developer, comprising the steps of: melt-kneading a mixture containing the amorphous polyester resin A, in which the polyethylene terephthalate content is 36 mol% or more and 70 mol% or less (where the polyethylene terephthalate content is the content in the total amount of alcohol component, carboxylic acid component, and polyethylene terephthalate, with terephthalate-ethylene glycol units considered as 1 mole); crushing and classifying the resulting mixture to obtain toner matrix particles; and mixing the obtained toner matrix particles with an external additive. A method for producing a dry-process toner according to claim 1 , wherein the IV value of polyethylene terephthalate is 0.40 or more and 0.80 or less. The method for manufacturing dry-process toner for development according to claim 1 or 2, wherein the open-roll twin-screw kneader is a kneader equipped with two rolls having different peripheral speeds, the roll with the higher peripheral speed being the heating roll and the roll with the lower peripheral speed being the cooling roll. A method for fixing toner, comprising fixing a dry-process developing toner obtained by the method described in claim 1 or 2 onto a medium using heat and pressure.