JP2022080728A - Method for manufacturing toner - Google Patents

Abstract

To provide a method for manufacturing a toner that is excellent in low-temperature fixability and a transfer property.SOLUTION: A method for manufacturing a toner includes: a step 1 of melting and mixing a mixture containing a binder resin containing a crystalline polyester resin and a non-crystalline polyester resin, a color agent, and a mold parting agent; a step 2 of breaking the obtained mixture into pieces, separating the pieces, for obtaining toner particles; a step 3 of dispersing the obtained toner particles into an aqueous medium under the presence of a surface-active agent to obtain a toner particle dispersion liquid; and a step 4 of heating the toner particle dispersion liquid at a temperature rising rate of at least 15°C/min. An average circularity of the obtained toner is at least 0.965.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a toner used for developing a latent image formed by an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

In the field of electrophotographic, with the development of electrophotographic systems, there is a demand for the development of toner for static charge image development corresponding to further improvement in image quality. As a method for obtaining toner having a narrow particle size distribution and a small particle size in response to higher image quality, a coagulation fusion method (emulsification) in which fine resin particles and the like are aggregated and fused in an aqueous medium to obtain toner. It is manufactured by the agglomeration method and the agglomeration union method). Further, since it is also effective to improve the transferability by making the toner shape spherical in order to improve the image quality, a technique for making the toner shape spherical by a so-called chemical toner such as the above-mentioned coagulation fusion method or suspension polymerization method. Has been proposed.

On the other hand, a technique for controlling the shape of a crushed toner obtained by crushing a melt-kneaded raw material is disclosed, and Patent Document 1 discloses a crushed toner to be heated and sphericalized in a solvent to form a toner surface roughness index. Describes a method for producing a toner having excellent transferability by forming toner particles in the range of 1.1 to 1.5 and setting the coverage of the inorganic fine powder on the surface of the toner particles in the range of 30 to 50%. Has been done.

Further, in Patent Document 2, as a means for spheroidizing and improving transferability, a masterbatch of a colorant in which a colorant is dispersed in a resin is melt-kneaded in advance together with a binder resin as a toner component and other additives. Described is a method for producing a toner obtained by kneading a substance soluble in the aqueous phase or kneading with a masterbatch and then dispersing the kneaded material to the toner size in the aqueous phase by mechanical energy. There is.

Patent Document 3 describes a technique capable of suppressing toner sticking while ensuring fixability by forming a core-shell toner by wet dispersion after producing pulverized toner using polyester.

Japanese Unexamined Patent Publication No. 9-43905 Japanese Patent Application Laid-Open No. 2002-244348 Japanese Unexamined Patent Publication No. 2017-181873

However, none of the toners of Patent Documents 1 to 3 is sufficient to achieve both low temperature fixability and transferability. It is widely known that a crystalline polyester resin is used to improve low-temperature fixability. However, when a toner is produced by melt-kneading or crushing using the crystalline polyester resin, a toner having a high circularity should be produced. Is difficult.

The present invention relates to a method for producing a toner having excellent low temperature fixability and transferability.

The present invention is a step of melt-kneading a mixture containing a binder resin containing a crystalline polyester resin and an amorphous polyester resin, a colorant, and a release agent 1. The obtained kneaded product is crushed and classified. Step 2, the obtained toner particles are dispersed in an aqueous medium in the presence of a surfactant to obtain a toner particle dispersion, and the temperature of the obtained toner particle dispersion is raised. The present invention relates to a method for producing toner, which comprises a step 4 of heating at 15 ° C./min or more, wherein the average circularity of the obtained toner is 0.965 or more.

The toner obtained by the method of the present invention exerts excellent effects in low temperature fixability and transferability.

In the present invention, the toner particles obtained by melt-kneading a mixture containing a binder resin containing a crystalline polyester resin and an amorphous polyester resin, a colorant, and a release agent and pulverizing the toner particles are surface-active. This is a method of obtaining a toner having a high circularity by dispersing it in an aqueous medium in the presence of an agent and heating the obtained toner particle dispersion at a temperature rising rate of a predetermined value or higher.
By using a crystalline polyester resin as the binder resin, the low temperature fixability can be improved. When crushed toner is obtained using a crystalline polyester resin, the method of increasing the circularity of the toner is a method of spheroidizing with a mechanical shearing force or a method of spraying powder in a high temperature atmosphere to form a spheroid. The method and the like can be mentioned. However, in the former method, since the crystalline polyester resin has a lower hardness than the amorphous polyester resin, the corners of the toner particles are not easily scraped by shearing, excessive heating is required for spheroidization, and secondary aggregation occurs. It will be easier. Further, in the latter method, since the crystalline polyester resin causes a rapid decrease in viscosity above the melting point, it is easily exposed on the toner surface, and there is a concern that the toner performance such as a decrease in charge and a decrease in durability may be deteriorated. As described above, it is difficult to obtain a toner having a high circularity with a pulverized toner using a crystalline polyester resin. On the other hand, in the present invention, by heating the toner particle dispersion liquid at a temperature rising rate of a predetermined value or higher, it becomes possible to make the toner particles spherical without impairing the particle size of the toner particles, and a pulverized toner having a high circularity can be obtained. Is improved. Although the detailed reason why the spheroidization of the toner is promoted by the method of the present invention is unknown, it is presumed as follows.

When the toner particles are sphericalized in water, the toner particles are plastically deformed, so that it is necessary to raise the temperature to a temperature higher than the glass transition temperature of the contained binder resin and close to the softening temperature. When the temperature of the toner particle dispersion liquid containing the crystalline polyester resin is gradually raised, it is difficult for the surfactant, which is a dispersant, to be adsorbed on the crystal site, and the motility of the surfactant increases before plastic deformation occurs, resulting in desorption. Therefore, it is considered that the toner particles become unstable and secondary aggregation occurs. On the other hand, in the present invention, by heating the toner particle dispersion liquid at a heating rate of a predetermined value or higher in a short time, plastic deformation of the toner particles occurs before the desorption of the surfactant occurs, so that the crystalline polyester resin is used. It is considered that sphericalization is possible even if it contains.

The method for producing the toner of the present invention is
Step 1: A step of melt-kneading a mixture containing a binder resin containing a crystalline polyester resin and an amorphous polyester resin, a colorant, and a mold release agent.
Step 2: A step of crushing the obtained kneaded product and classifying it to obtain toner particles.
Step 3: The obtained toner particles are dispersed in an aqueous medium in the presence of a surfactant to obtain a toner particle dispersion liquid, and Step 4: the obtained toner particle dispersion liquid is heated at a heating rate of 15 ° C./ It is a method including a step of heating at min or more.

As the crystalline polyester resin, a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound is preferable.

The crystallinity of the resin is represented by the crystallinity index defined by the ratio of the softening point to the maximum endothermic temperature by the differential scanning calorimeter, that is, the value of [softening point / maximum endothermic temperature]. The crystalline resin is a resin having a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less.
On the other hand, the amorphous resin is a resin having a crystallinity index of more than 1.4, preferably more than 1.5, more preferably 1.6 or more, or less than 0.6, if no endothermic peak is observed or if it is observed. A resin of 0.5 or less is preferable.
The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, the production conditions (for example, reaction temperature, reaction time, cooling rate) and the like. The maximum endothermic temperature refers to the temperature of the peak with the largest endothermic area among the observed endothermic peaks. In the crystalline resin, the maximum peak temperature of endothermic is taken as the melting point.

The aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,7-heptanediol. , 1,8-octanediol, neopentyl glycol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, etc. , Two or more may be used together.

From the viewpoint of low-temperature fixability, the aliphatic diol is preferably an α, ω-aliphatic diol having a hydroxyl group at the end of the carbon chain, and more preferably an α, ω-linear alkane diol. ..

The carbon number of the aliphatic diol is preferably 2 or more, more preferably 4 or more, still more preferably 6 or more, and preferably 16 or less, more preferably 16 or less, from the viewpoint of low temperature fixability. It is 14 or less, more preferably 12 or less, still more preferably 8 or less.

The content of the aliphatic diol is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 100 mol% in the alcohol component. be.

Examples of other alcohol components include aromatic diols such as alkylene oxide adducts of bisphenol A, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trimethylolpropane and the like, and the like.

Examples of the aliphatic dicarboxylic acid compound include succinic acid (carbon number: 4), fumaric acid (carbon number: 4), adipic acid (carbon number: 6), suberic acid (carbon number: 8), and azelaic acid (carbon number: 8). : 9), sebacic acid (carbon number: 10), dodecanedioic acid (carbon number: 12), tetradecanedioic acid (carbon number: 14), succinic acid having an alkyl group or alkenyl group in the side chain, of these acids Examples thereof include anhydrides and alkyl esters having 1 or more and 3 or less carbon atoms of these acids.

The carbon number of the aliphatic dicarboxylic acid compound is preferably 4 or more, more preferably 6 or more, still more preferably 8 or more from the viewpoint of low temperature fixability, and preferably 14 or less from the viewpoint of storage stability. More preferably, it is 12 or less.

The content of the aliphatic dicarboxylic acid compound is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 95 mol% or more in the carboxylic acid component. It is 100 mol%.

Examples of other carboxylic acid components include aromatic dicarboxylic acid compounds and carboxylic acid compounds having a valence of 3 or more.

The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate from the viewpoint of adjusting the molecular weight and softening point of the polyester resin.

The equivalent ratio (COOH group / OH group) of the carboxylic acid component and the alcohol component is preferably 0.8 or more, more preferably 0.9 or more from the viewpoint of storage stability, and preferably 1.2 or less from the viewpoint of low temperature fixability. , More preferably 1.1 or less.

The crystalline polyester resin has, for example, an alcohol component and a carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and if necessary, in the presence of an esterification co-catalyst, a polymerization inhibitor, or the like. It can be preferably produced by polycondensation at a temperature of 120 ° C. or higher and 230 ° 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 diisopropyrate bistriethanol aminated, and tin compounds are preferable. The amount of the esterification catalyst used is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and preferably 1.5 parts by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. It is preferably 1 part by mass or less. Examples of the esterification co-catalyst include gallic acid and the like. The amount of the esterification co-catalyst used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. More preferably, it is 0.1 part by mass or less. Examples of the polymerization inhibitor include t-butylcatechol and the like. The amount of the polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. It is preferably 0.1 parts by mass or less.

In the present invention, the polyester resin may be a polyester resin modified to such an extent that its characteristics are not substantially impaired. Examples of the modified polyester resin include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636 and the like. Examples thereof include the modified polyester resin, and among the modified polyester resins, a urethane-modified polyester resin obtained by urethane-stretching the polyester resin with a polyisocyanate compound is preferable.

The softening point of the crystalline polyester resin is preferably 50 ° C. or higher, more preferably 65 ° C. or higher, still more preferably 70 ° C. or higher from the viewpoint of storage stability, and preferably 120 ° C. from the viewpoint of low temperature fixability. Below, it is more preferably 110 ° C. or lower.

The melting point of the crystalline polyester resin is preferably 60 ° C. or higher, more preferably 70 ° C. or higher from the viewpoint of storage stability, and preferably 130 ° C. or lower, more preferably 120 ° C. or lower, from the viewpoint of low temperature fixability. Is.

The content of the crystalline polyester resin in the binder resin is preferably 5% by mass or more, more preferably 8% by mass or more from the viewpoint of low-temperature fixability, and preferably 45% by mass from the viewpoint of transferability. % Or less, more preferably 35% by mass or less, still more preferably 25% by mass or less, still more preferably 20% by mass or less, still more preferably 12% by mass or less.

As the amorphous polyester resin, a polycondensate of an alcohol component containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component containing an aromatic dicarboxylic acid compound is preferable.

As an alkylene oxide adduct of bisphenol A, the formula (I):

(In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, and x and y indicate the average number of moles of alkylene oxide added, which are positive numbers, respectively, and x and y. The value of the sum of is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, still more preferably 4 or less).
The compound represented by is preferable.

The content of the alkylene oxide adduct of bisphenol A is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more in the alcohol component from the viewpoint of low temperature fixability. More than mol%, more preferably 100 mol%.

Examples of other alcohol components include trihydric or higher alcohols such as aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, and trimethylolpropane.

Examples of the aromatic dicarboxylic acid compound include phthalic acid, isophthalic acid, terephthalic acid, anhydrates of these acids, and alkyl esters having 1 or more and 3 or less carbon atoms in these acids.

The content of the aromatic dicarboxylic acid compound is preferably 10 mol% or more, more preferably 25 mol% or more, still more preferably 40 mol% or more, and the carboxylic acid in the carboxylic acid component from the viewpoint of charge stability. When the component contains other carboxylic compounds, it is preferably 100 mol% or less, more preferably 90 mol% or less, still more preferably 80 mol% or less.

Examples of other carboxylic acid components include aliphatic dicarboxylic acid-based compounds and carboxylic acid-based compounds having a trivalent or higher valence, and from the viewpoint of increasing the softening point, it is preferable to include a carboxylic acid-based compound having a trivalent or higher valence. ..

Examples of the trivalent or higher carboxylic acid compound include trimellitic acid, pyromellitic acid, anhydrates of these acids, and alkyl esters having 1 or more and 3 or less carbon atoms of these acids.

The content of the trivalent or higher carboxylic acid compound is preferably 3 mol% or more, more preferably 5 mol% or more, still more preferably 8 mol% or more in the carboxylic acid component from the viewpoint of increasing the softening point. From the viewpoint of efficiently performing spheroidization in an aqueous medium, the content is preferably 35 mol% or less, more preferably 25 mol% or less, still more preferably 20 mol% or less.

The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate from the viewpoint of adjusting the molecular weight and softening point of the polyester resin.

The equivalent ratio of the carboxylic acid component to the alcohol component (COOH group / OH group) is preferably 0.6 or more, more preferably 0.7 or more, still more preferably 0.75 or more, and more preferably 0.75 or more, from the viewpoint of adjusting the softening point of the polyester resin. It is preferably 1.2 or less, more preferably 1.15 or less.

The polycondensation reaction conditions between the alcohol component and the carboxylic acid component of the amorphous polyester resin are such that a suitable reaction temperature is preferably 130 ° C. or higher, more preferably 170 ° C. or higher, and preferably 250 ° C. or lower, more preferably 240 ° C. or higher. The reaction conditions are the same as those of the crystalline polyester resin except that the temperature is below ° C.

The softening point of the amorphous polyester resin is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, and preferably 150 ° C. or lower, more preferably 150 ° C. or higher, from the viewpoint of storage stability. It is 140 ° C or less.

The amorphous polyester resin may be made of a resin having a different softening point from the viewpoint of low-temperature fixability and efficient spherical formation. The difference in softening points between the two resins is preferably 10 ° C. or higher, more preferably 15 ° C. or higher, still more preferably 20 ° C. or higher, still more preferably 30 ° C. or higher, and preferably 70 ° C. or lower, more preferably 70 ° C. or higher. Is below 60 ° C.

The softening point of the amorphous polyester resin (resin H) having a higher softening point is preferably 120 ° C. or higher, more preferably 125 ° C. or higher, still more preferably 130 ° C. from the viewpoint of improving the durability and storage stability of the toner. The temperature is preferably 160 ° C. or higher, more preferably 135 ° C. or higher, and preferably 160 ° C. or lower, more preferably 150 ° C. or lower, from the viewpoint of improving the low temperature fixability of the toner.

Further, the softening point of the amorphous polyester resin (resin L) having the lower softening point is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, and the toner, from the viewpoint of improving the durability of the toner. From the viewpoint of improving the low temperature fixability of the material, the temperature is preferably 120 ° C. or lower, more preferably 115 ° C. or lower, still more preferably 110 ° C. or lower, still more preferably 105 ° C. or lower, still more preferably 100 ° C. or lower.

The mass ratio of the resin H to the resin L (resin H / resin L) is preferably 10/90 or more, more preferably 20/80 or more, still more preferably 40/60 or more, still more preferably 50/50 or more, still more preferable. Is 60/40 or more, and is preferably 90/10 or less, more preferably 80/20 or less, and even more preferably 70/30 or less.

The glass transition temperature of the amorphous polyester resin is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and preferably 80 ° C. or lower, more preferably 80 ° C. or higher, from the viewpoint of storage stability. Is 70 ° C. or lower, more preferably 65 ° C. or lower.

The acid value of the amorphous polyester resin is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more from the viewpoint of low-temperature fixability, and preferably 20 mgKOH / g or less from the viewpoint of hygroscopicity. It is preferably 15 mgKOH / g or less, more preferably 10 mgKOH / g or less.

The mass ratio of the crystalline polyester resin to the amorphous polyester resin (crystalline polyester resin / amorphous polyester resin) is preferably 2/98 or more, more preferably 5/95 or more, and further, from the viewpoint of low temperature fixability. It is preferably 10/90 or more, and from the viewpoint of durability, it is preferably 45/55 or less, more preferably 25/75 or less, still more preferably 20/80 or less.

Examples of other binding resins include vinyl-based resins such as styrene acrylic resin, epoxy resins, polycarbonates, polyurethanes, and composite resins containing two or more of these resins.

The total content of the crystalline polyester resin and the amorphous polyester resin is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass in the binder resin. As mentioned above, it is 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, further preferably 80% by mass or more, and preferably less than 100% by mass, more preferably. It is 98% by mass or less, more preferably 95% by mass or less.

As the colorant, dyes, pigments, magnetic materials and the like used as colorants for toner can be used. For example, 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, Carmin 6B, Isoindoline, Disazoero And so on. In the present invention, the toner may be either black toner or color toner.

The content of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and more preferably 2 parts by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint of improving the image concentration and low temperature fixability of the toner. It is preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 10 parts by mass or less.

As the release agent, hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene polyethylene copolymer wax, microcrystallin wax, paraffin wax, Fishertropch wax, and sazole wax and their oxides; carnauba wax, montane. Waxes and ester waxes such as deoxidized waxes and fatty acid ester waxes; fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and the like can be mentioned, and these can be used alone 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 transferability, and preferably 160 ° C. or lower, more preferably 140 ° C. or lower, from the viewpoint of low temperature fixability. It is more preferably 120 ° C. or lower, still more preferably 110 ° C. or lower.

The content of the release agent is preferably 0.5 part by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint of low temperature fixing property and offset resistance of the toner and dispersibility in the binder resin. It is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, still more preferably 7 parts by mass or less.

In addition to the binder resin, colorant, and mold release agent, the mixture contains a charge control agent, a magnetic powder, a fluidity improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, and an improvement in cleaning property. It may contain additives such as agents.

The charge control agent is not particularly limited and may contain either a positive charge control agent or a negative charge control agent.

Positive charge control agents include niglosin dyes such as "niglocin base EX", "oil black BS", "oil black SO", "bontron N-01", "bontron N-04", and "bontron N-07". , "Bontron N-09", "Bontron N-11" (all manufactured by Orient Chemical Industry Co., Ltd.), etc .; Triphenylmethane dyes containing a tertiary amine as a side chain; a quaternary ammonium salt compound, for example. "Bontron P-51" (manufactured by Orient Chemical Industry Co., Ltd.), cetyltrimethylammonium bromide, "COPY CHARGE PX VP435" (manufactured by Clariant), etc .; (Manufactured by), etc .; imidazole derivatives such as "PLZ-2001", "PLZ-8001" (all manufactured by Shikoku Kasei Kogyo Co., Ltd.), etc .; styrene-acrylic resin, for example, "FCA-701PT", "FCA-201-" PS ”(manufactured by Fujikura Kasei Co., Ltd.) and the like.

Examples of the negative charge control agent include metal-containing azo dyes such as "Varifast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", and "Bontron S-36". (The above is manufactured by Orient Chemical Industry Co., Ltd.), "Eisenspiron Black TRH", "T-77" (manufactured by Hodoya Chemical Industry Co., Ltd.), etc .; Metal compounds of benzylic acid compounds, for example, "LR-" 147 ”,“ LR-297 ”(above, manufactured by Nippon Carlit Co., Ltd.), etc .; Metal compounds of salicylic acid compounds, for example,“ Bontron E-81 ”,“ Bontron E-84 ”,“ Bontron E-88 ”,“ Bontron E-304 "(above, manufactured by Orient Chemical Industry Co., Ltd.)," TN-105 "(manufactured by Hodoya Chemical Industry Co., Ltd.), etc .; copper phthalocyanine dye; quaternary ammonium salt, for example," COPY CHARGE NX VP434 " (Manufactured by Clariant), nitroimidazole derivatives, etc .; examples include organic metal compounds.

The content of the charge control agent is preferably 0.01 part by mass or more, more preferably 0.2 part by mass or more, and preferably 10 parts by mass with respect to 100 parts by mass of the binder resin from the viewpoint of charge stability of the toner. Parts or less, more preferably 5 parts by mass or less.

The mixture to be subjected to melt-kneading may be subjected to kneading at one time or divided and subjected to kneading, but it is preferable to mix the mixture in advance with a mixer such as a Henschel mixer or a ball mill and then supply the mixture to the kneader.

The melt kneading can be performed by using a known kneader such as a closed kneader, a single-screw or twin-screw extruder, or an open roll type kneader.

The temperature of melt-kneading is not particularly limited as long as the resin is melted and mixed.

After the melt-kneading step (step 1), the kneaded product is appropriately cooled until it reaches a hardness that can be crushed, and the obtained kneaded product is crushed and classified to obtain toner particles (step 2). Here, cooling means cooling the kneaded product to 0 ° C. or higher and 50 ° C. or lower, or cooling the kneaded resin to a glass transition temperature or lower of the binder resin in the kneaded product.

In the pulverization of the kneaded product, the kneaded product may be pulverized at once or stepwise to a desired particle size, but from the viewpoint of efficient and more uniform pulverization, coarse pulverization and fine pulverization are performed. It is preferable to carry out in two steps.

Examples of the crusher used for coarse crushing include a hammer mill, a cutter mill, an atomizer, and a rotoplex.

In coarse pulverization, it is preferable to pulverize until the maximum diameter becomes 3 mm or less. For example, for a pulverized product having a maximum diameter of 3 mm or less, the kneaded product is roughly pulverized until the particle size is 0.05 mm or more and 3 mm or less, and then passed through a sieve having a mesh opening of 3 mm to be used as a pulverized product that has passed through the sieve. Obtainable.

Examples of the pulverizer used for pulverization include a fluidized bed type jet mill, a jet mill such as a collision plate type jet mill, and a mechanical type mill.

The degree of fine pulverization is preferably adjusted as appropriate according to the particle size of the target toner particles.

Examples of the classifying machine used for classifying include an airflow type classifying machine, an inertial type classifying machine, and a sieve type classifying machine.

The softening point of the toner particles obtained in step 2 is preferably 90 ° C. or higher, more preferably 95 ° C. or higher, still more preferably 100 ° C. or higher, and preferably 130 ° C. or lower, more preferably 120 ° C. or lower. More preferably, it is 115 ° C. or lower.

The glass transition temperature of the toner particles is preferably 40 ° C. or higher, more preferably 43 ° C. or higher, still more preferably 45 ° C. or higher, and preferably 70 ° C. or lower, more preferably 65 ° C. or lower, still more preferably. It is below 60 ° C.

Subsequent step 3 is a step of dispersing the obtained toner particles in an aqueous medium in the presence of a surfactant to obtain a toner particle dispersion liquid.

As the surfactant, at least one selected from the group consisting of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant is preferable, and anionic from the viewpoint of detergency. At least one selected from the group consisting of surfactants, cationic surfactants, and amphoteric surfactants is more preferable.

Examples of the anionic surfactant include naphthalenesulfonic acid formarin condensate salt, polycarboxylic acid type polymer surfactant, polyoxyethylene alkyl ether sulfate ester salt, alkyl ether sulfate ester salt, alkylbenzene sulfonate, and alkylnaphthalene sulfonic acid. Examples thereof include salts, dialkyl sulfosuccinates, alkyldiphenyl ether disulfonates, fatty acid salts, polyoxyethylene alkyl ether phosphates, dipotassium alkenyl succinate, etc. Among these, formalin naphthalenesulfonate from the viewpoint of dispersion stability. A condensate, a polyoxyethylene alkyl ether sulfate ester salt, an alkyl ether sulfate ester salt, or an alkylbenzene sulfonate is preferable, and a naphthalene sulfonic acid formarin condensate is more preferable.

The naphthalene sulfonic acid formalin condensate can be produced by polycondensation using a known method, for example, β-naphthalene sulfonic acid (salt) and an equivalent amount of formalin and, if necessary, other components. Examples of other components include sulfonic acids (salts) such as β-methylnaphthalene, α-methylnaphthalene, acenaphthene, dibenzofuran, fluorene, phenanthrene, anthracene, fluorene, and pyrene.

Commercially available products of naphthalene sulfonic acid formarin condensate include, for example, Demor N, Demor NL, Demor RN, Demor RN-L, Demor T, Demor T-45, Demor MS, Demor SN-B, manufactured by Kao Co., Ltd. Demol SS-L, Demol SC-30, Labelin AN-40 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Labelin F-45, Labelin FC-45, Labelin FC-P, Labelin FD-40, Labelin FP, Labelin FN- Examples include P, Laberin MN-P, and Ionet D-2 manufactured by Sanyo Kasei Kogyo Co., Ltd.

Commercially available products of polyoxyethylene alkyl ether sulfate ester include, for example, Emar 20C, Emar E-27C, Emar 270J, Emar 20CM, Emar D-3-D, Emar D-4-D, manufactured by Kao Corporation. Examples thereof include Latemul E-118B, Latemul E-150, Levenol WX, and Latemul WX.
Examples of commercially available products of the alkyl ether sulfate ester salt include Emar 0 manufactured by Kao Corporation.
Examples of commercially available products of alkylbenzene sulfonate include Neoperex G-15 manufactured by Kao Corporation.

Examples of the cationic surfactant include an alkyltrimethylammonium salt, an alkylbenzyldimethylammonium salt, an alkylamine salt and the like.

Commercially available products of alkyltrimethylammonium salts include, for example, Kao Corporation's Coatamine 24P (lauryltrimethylammonium chloride), Coatamine 60W (cetyltrimethylammonium chloride), Coatamine 86W (stearyltrimethylammonium chloride), and Coatamine D86P (distearyl). Dimethylammonium chloride) and the like.
Examples of the alkylbenzyldimethylammonium salt include Sanizol C manufactured by Kao Corporation.

Examples of the amphoteric tenside agent include alkylamine oxides and alkylbetaines.
Examples of the alkylamine oxide include Anchtor 24B (lauryl betaine) and Anchtor 86B (stearyl betaine) manufactured by Kao Corporation.
Examples of the alkyl betaine include Anchtor 20N (lauryldimethylamine oxide) manufactured by Kao Corporation.

In the above-mentioned surfactant, as the anionic surfactant, a polymer-based anionic surfactant having a high dispersibility is preferable from the viewpoint of achieving both dispersion stability at high temperature in step 3, and naphthalene sulfonic acid formarin condensation. Salts are more preferred.
As the cationic surfactant, one having an alkyl chain is preferable from the viewpoint of imparting wettability of the toner particles to the aqueous medium in step 2.
As the amphoteric tenside, those having an alkyl chain are preferable as in the case of the cationic surfactant, and from the viewpoint of detergency after spheroidization, an amphoteric surfactant such as alkylbetaine in which the cationic moiety disappears depending on pH. Is even more preferable.
As the surfactant, any one of anionic surfactant, cationic surfactant, nonionic surfactant, and amphoteric surfactant can be used alone or in combination, but the aqueous medium of the toner particles can be used. From the viewpoint of dispersion stability in the environment, a combination of an anionic surfactant and a cationic surfactant or an amphoteric surfactant is preferable, and from the viewpoint of detergency, a combination of an anionic surfactant and an amphoteric surfactant is preferable. Is more preferable.
Further, as a combination of the anionic surfactant and the cationic surfactant or the amphoteric surfactant, in order to make the surfactant densely present on the toner surface from the viewpoint of further improving the stability at high temperature, A combination of the cationic moiety (hydrophilic group) of the cationic surfactant or the amphoteric surfactant and the anionic moiety of the anionic surfactant to form an electrostatic assembly is more preferable.

In the combination of the anionic surfactant and the cationic surfactant or the amphoteric surfactant, the mass ratio of the two (anionic surfactant / cationic surfactant or amphoteric surfactant) is preferably 50/50. The above is more preferably 70/30 or more, further preferably 80/20 or more, and preferably 98/2 or less, more preferably 96/4 or less.

In the combination of the anionic surfactant and the cationic surfactant or the amphoteric surfactant, the molar ratio of both (anionic surfactant / cationic surfactant or amphoteric surfactant) is preferably 10/90. The above is more preferably 30/70 or more, still more preferably 40/60 or more, still more preferably 50/50 or more, and preferably 90/10 or less, more preferably 80/20 or less, still more preferably 70 /. It is 30 or less.

The amount of the surfactant used is preferably 2 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 20 parts by mass or more, and preferably 100 parts by mass or less with respect to 100 parts by mass of the toner particles. , More preferably 80 parts by mass or less, still more preferably 60 parts by mass or less.

The aqueous medium contains water in an amount of preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, still more preferably 99% by mass or more. Water alone may be used, but a solvent miscible with water may be used in combination. Examples of the solvent miscible with water include alcohols (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellsolve (registered trademark) (methylcellsolve, etc.), lower ketones (acetone, methylethylketone, etc.), and the like. Be done.

Toner particles are mixed with a surfactant and an aqueous medium and stirred to disperse.

The concentration of the toner particles in the toner particle dispersion is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and dispersed from the viewpoint of ease of spheroidization. From the viewpoint of stability, it is preferably 50% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less.

The temperature of the toner particle dispersion obtained in step 3 is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, still more preferably 40 ° C. or higher, and is preferably amorphous from the viewpoint of dispersion stability of the toner particles. Crystalline polyester resin glass transition temperature + 20 ° C or less, more preferably amorphous polyester resin glass transition temperature + 10 ° C or less, still more preferably amorphous polyester resin glass transition temperature + 5 ° C or less, still more preferably amorphous It is below the glass transition temperature of the polyester resin. When the amorphous polyester resin is composed of two or more kinds of resins, the "glass transition temperature of the amorphous polyester resin" refers to the weighted average value thereof.

Step 4 is a step of heating the obtained toner particle dispersion liquid at a heating rate of 15 ° C./min or more.

The rate of temperature rise of the toner particle dispersion is 15 ° C./min or higher, preferably 40 ° C./min or higher, more preferably 100 ° C./min or higher, and the toner, from the viewpoint of suppressing aggregation of the toner particles. The upper limit of the temperature rising rate of the particle dispersion may be within the range possible by the heating means adopted from the viewpoint of actual production, and the faster it is, the better from the viewpoint of sphericalization.

As a heating means of the toner particle dispersion liquid, a method of mixing the toner particle dispersion liquid with an aqueous medium having a temperature higher than that of the toner particle dispersion liquid is preferable, and as a mixing method, an in-line mixer, a T-shaped pipe, a Y-shaped pipe or the like is used. Can be used. Other heating means include heat exchange and the like. The temperature of the aqueous medium to be mixed with the toner particle dispersion is preferably 90 ° C. or higher, more preferably 95 ° C. or higher, still more preferably 98 ° C. or higher, and preferably 100 ° C. or lower.

In step 4, the toner particle dispersion liquid preferably heats the toner particles to a temperature at which they can be sphericalized. The temperature is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, still more preferably 90 ° C. or higher, and preferably 100 ° C. or lower, more preferably 98 ° C. or higher from the viewpoint of preventing fusion to the container wall surface. Below, it is more preferably 96 ° C. or lower.

From the viewpoint of productivity, the concentration of the toner particles in the toner particle dispersion heated in step 4 is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, and From the viewpoint of suppressing aggregation of toner particles, it is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less.

From the viewpoint of advancing spheroidization, the toner particle dispersion heated in step 4 is preferably at a temperature equal to or higher than the glass transition temperature of the amorphous polyester resin, specifically, preferably 70 ° C. or higher, and is preferable. Is preferably subjected to the holding step 5 at a temperature of 98 ° C. or lower, more preferably 96 ° C. or lower. When the amorphous polyester resin is composed of two or more kinds of resins, the glass transition temperature of the amorphous polyester resin shall indicate the weighted average value thereof.

The holding time is preferably 0.5 minutes or more, more preferably 1 minute or more from the viewpoint of advancing spheroidization, and preferably 15 minutes or less, more preferably 10 minutes from the viewpoint of suppressing the aggregation of toner particles. It is as follows.

Then, after the step 4 or the step 5, the toner particle dispersion liquid is cooled. Examples of the cooling means include a method of mixing with cold water, a method of spraying a toner particle dispersion, and the like.

The cooling temperature is preferably 10 ° C. or higher, more preferably 15 ° C. or higher, still more preferably 20 ° C. or higher, and preferably 70 ° C. or lower, more preferably 65 ° C. or lower, still more preferably 60 ° C. or lower. ..

In the present invention, in step 4, sphericalization is started by raising the temperature of the toner particle dispersion, and the toner particles are held at a temperature equal to or higher than the glass transition temperature of the amorphous polyester resin. Sphericalization progresses. Therefore, the time from the start of heating of the toner particle dispersion liquid in step 4 to cooling to a temperature equal to or lower than the glass transition temperature of the amorphous polyester resin is defined as the sphericalization time.

The spheroidization time is preferably 0.5 minutes or more, more preferably 1 minute or more from the viewpoint of advancing the spheroidization, and preferably 15 minutes or less, more preferably 10 minutes or less from the viewpoint of suppressing the aggregation of toner particles. Less than a minute.

Toner particles are obtained by appropriately dehydrating, washing, and drying the toner particle dispersion liquid.

In the present invention, it is preferable to have an external addition step of further mixing the obtained toner particles with an external additive.

Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin particles such as melamine-based resin fine particles and polytetrafluoroethylene resin fine particles. The above may be used together. Among these, silica is preferable, and from the viewpoint of toner transferability, hydrophobicized silica is more preferable.

Examples of the hydrophobizing agent for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazan, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltri. Examples thereof include ethoxysilane.

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

From the viewpoint of the chargeability, fluidity, and transferability of the toner, the content of the external additive is preferably 0.05 part by mass or more, more preferably 0.1 mass by mass, based on 100 parts by mass of the toner before being treated with the external additive. More than parts, more preferably 0.3 parts by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less.

The average circularity of the toner obtained by the method of the present invention is 0.965 or more, preferably 0.970 or more, more preferably 0.980 or more, and 1 or less, preferably 0.995 or less, from the viewpoint of transferability. be. When the toner is treated with an external additive, the average circularity of the toner particles before being treated with the external additive is used.

The volume median particle size (D ₅₀ ) of the toner 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 the present specification, the volume median particle size (D ₅₀ ) means a particle size in which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size. When the toner is treated with an external additive, the volume median particle diameter of the toner particles before the toner is treated with the external additive is defined as the volume median particle diameter of the toner.

The toner obtained by the method of the present invention is used as it is as a toner for one-component development or as a toner for two-component development used by mixing with a carrier in a one-component development method or a two-component development method image forming apparatus, respectively. be able to.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The physical characteristics of the resin and the like can be measured by the following methods.

[Softening point (Tm) of resin and toner, maximum peak temperature of heat absorption of resin, and glass transition temperature (Tg) of resin and toner]
(1) Using the softening point flow tester "CFT-500D" (manufactured by Shimadzu Corporation), a 1 g sample is heated at a heating rate of 6 ° C / min, and a load of 1.96 MPa is applied by a plunger to form a diameter. Extruded from a 1 mm, 1 mm long nozzle. The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is used as the softening point.
(2) Maximum endothermic temperature and glass transition temperature Using a differential scanning calorimeter "Q100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.02 g of the sample into an aluminum pan and raise the temperature to 200 ° C. Then, cool from that temperature to 0 ° C at a temperature lowering rate of 10 ° C / min. Next, the sample is heated at a heating rate of 10 ° C./min, and the amount of heat is measured. Of the observed endothermic peaks, the temperature of the peak with the largest peak area is defined as the maximum endothermic temperature. In the case of crystalline resin, the peak temperature is used as the melting point.
In the case of an amorphous resin, the temperature at the intersection of the extension of the baseline below the maximum peak temperature of heat absorption and the tangent line showing the maximum slope from the rising portion of the peak to the peak of the peak is defined as the glass transition temperature. ..

[Acid value of resin]
Measure according to the neutralization titration method described in JIS K 0070: 1992. However, only the measurement solvent is from the mixed solvent of ethanol and ether specified in JIS K 0070, the amorphous resin is the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)), and the crystalline resin is. Change to a mixed solvent of chloroform and dimethylformamide (chloroform: dimethylformamide = 7: 3 (volume ratio)).

[Melting point of mold release agent]
Using a differential scanning calorimeter "Q100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.02 g of the sample into an aluminum pan, raise the temperature to 200 ° C, and then lower the temperature from 200 ° C to 10 ° C / min. Cool to 0 ° C. Next, the sample is heated at a heating rate of 10 ° C./min, the amount of heat is measured, and the maximum peak temperature of endotherm is taken as the melting point.

[Average particle size of external additive]
The average particle size refers to the number average particle size, and the particle size (the average value of the major axis and the minor axis) of 500 particles is measured from a scanning electron microscope (SEM) photograph, and the number average value thereof is used.

[Medium particle size of toner (D ₅₀ )]
-Measuring machine: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter Co., Ltd.)
・ Aperture diameter: 50 μm
-Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter Co., Ltd.)
-Electrolytic solution: "Isoton (registered trademark) II" (manufactured by Beckman Coulter Co., Ltd.)
-Dispersion: Polyoxyethylene lauryl ether "Emargen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Hydrophile-Lipophile Balance) = 13.6] is dissolved in the electrolyte to prepare a dispersion with a concentration of 5% by mass. obtain.
-Dispersion conditions: Add 10 mg of the measurement sample to 5 mL of the dispersion, disperse with an ultrasonic disperser for 1 minute, then add 25 mL of electrolytic solution, and further disperse with an ultrasonic disperser for 1 minute. Prepare a sample dispersion.
-Measurement conditions: By adding the sample dispersion to 100 mL of the electrolytic solution, the particle size of 30,000 particles is adjusted to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured and the particle size is measured. The volume median particle size (D ₅₀ ) is obtained from the distribution.

[Average circularity of toner]
-Measuring device: Flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation)
-Preparation of dispersion: Prepare the dispersion of toner particles by diluting it with deionized water so that the solid content concentration is 0.001 to 0.05% by mass.
-Measurement mode: Calculate the average circularity of 1000 measurements in HPF measurement mode and total count mode.

Resin production example 1
The raw material monomers, esterification catalysts and polymerization inhibitors shown in Table 1 are placed in a 10-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and heated to 130 ° C. under a nitrogen atmosphere. Then, the temperature was raised from 130 ° C. to 200 ° C. over 10 hours, and the pressure was further reduced to 8 kPa while maintaining the temperature at 200 ° C. and reacted for 1 hour to obtain a crystalline polyester resin (resin C1). Table 1 shows the physical characteristics of the obtained resin.

Resin production example 2
A raw material monomer other than trimellitic anhydride and an esterification catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and placed at 230 ° C. under a nitrogen atmosphere. The temperature was raised to 5 and the reaction was carried out for 5 hours. Further, the pressure was reduced to 8 kPa and the reaction was carried out for 1 hour. Then, after returning to atmospheric pressure, the mixture was cooled to 190 ° C., trimellitic acid anhydride was added, the temperature was raised to 210 ° C. at 10 ° C./h, and then the reaction was carried out at 10 kPa to the desired softening point. A crystalline polyester resin (resin A1) was obtained. The physical characteristics are shown in Table 2.

Resin production example 3
The raw material monomers and esterification catalysts shown in Table 2 are placed in a 10-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and heated to 230 ° C. under a nitrogen atmosphere8. After reacting for a time, the pressure in the flask was lowered, and the reaction was carried out at 8 kPa to a desired softening point to obtain an amorphous polyester resin (resin A2). Table 2 shows the physical characteristics of the obtained resin.

Example 1
(Step 1)
100 parts by mass of binder resin shown in Table 3, 5 parts by mass of colorant "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue), positive charge charge control resin "FCA-201-PS" (Fujikura) After mixing 5 parts by mass of Kasei Co., Ltd. and 2 parts by mass of the release agent "HNP-9" (manufactured by Nippon Seiwa Co., Ltd., paraffin wax, melting point: 79 ° C) for 1 minute using a Henshell mixer. , Melt-kneaded using the same-direction rotary twin-screw extruder PCM-30 (manufactured by Ikekai Iron Works Co., Ltd.). The operating conditions were a barrel set temperature of 120 ° C, a shaft rotation speed of 200 r / min, and a mixture supply speed of 10 kg / h.

(Step 2)
The obtained kneaded product was cooled and coarsely pulverized by a crusher "Rotoplex" (manufactured by Hosokawa Micron Co., Ltd.), and a coarsely pulverized product having a volume particle size of 2 mm or less was obtained using a sieve having a mesh size of 2 mm. The obtained coarsely pulverized material is finely pulverized with a DS2 type airflow classifier (collision plate type, manufactured by Nippon Pneumatic Co., Ltd.), and then used with a DSX2 type airflow classifier (manufactured by Nippon Pneumatic Co., Ltd.) to have a volume median particle size of 7.5. The static pressure was adjusted so as to be μm, and classification was performed to obtain toner particles. Table 3 shows the physical characteristics of the obtained toner particles.

(Step 3)
After mixing 10.7 g (0.016 mol) of amphoteric surfactant (lauryldimethylamine oxide (Anchtor 20N, manufactured by Kao Co., Ltd., active ingredient 35% by mass)) and 321 g of deionized water in a 2 liter separable flask, 150 g of toner particles were added, and the mixture was stirred at 25 ° C. After the toner particles are sufficiently dispersed, 28% by mass of an anionic surfactant (Na salt of β-naphthalene sulfonic acid formarin condensate (Demor N, manufactured by Kao Co., Ltd., 100% active ingredient)) is added to deionized water. To 268 g (0.025 mol) of the diluted aqueous solution was added. The toner particle concentration at this time was 20% by mass. The temperature was raised to 60 ° C. (system temperature) while dispersing the toner particles by stirring, and the toner particle dispersion was kept at the same temperature.

(Step 4)
On the other hand, 3000 g of deionized water having a toner particle concentration of 4% by mass was weighed in a 5 liter separable flask and heated to 100 ° C. Then, the toner particle dispersion was added to the deionized water at 100 ° C. The temperature (final temperature) of the system after 6 seconds of mixing was 93 ° C., and the heating rate was 330 ° C./min ((93-60) ° C./0.1 min).

After holding at the same temperature for 8 minutes (step 5), cold water was added and rapidly cooled to 60 ° C. After cooling, it was dehydrated, washed and dried to obtain toner particles.

100 parts by mass of these toner particles, 0.5 parts by mass of hydrophobic silica "TG820F" (manufactured by Cabot, hydrophobizing agent: HMDS and cyclic sislazane, average particle diameter 8 nm) and hydrophobic silica "NA50Y" (manufactured by Cabot) Hydrophobic treatment agent manufactured by Nippon Aerosil Co., Ltd .: silicone oil and aminosilane, average particle diameter 40 nm) 1 part by mass was added and mixed with a Henshell mixer for 5 minutes to obtain the toner of Example 1. Table 3 shows the physical characteristics of the obtained toner.

Example 2
In step 3, instead of the amphoteric surfactant, a cationic surfactant (cetyltrimethylammonium chloride (Cotamin 60W, manufactured by Kao Co., Ltd., active ingredient 30% by mass)), 12.5 g (0.012 mol) was used. Toners were prepared in the same manner as in Example 1 except that the amount of deionized water to be mixed with the cationic surfactant was changed to 319 g. Table 3 shows the physical characteristics of the obtained toner.

Example 3
Example 1 except that the temperature (system temperature) of the toner particle dispersion in step 3 was changed to 70 ° C., and as a result, the final temperature in step 4 was 95 ° C. and the temperature rise rate was 250 ° C./min. Toner was prepared in the same manner as above. Table 3 shows the physical characteristics of the obtained toner.

Examples 4 and 5 and Comparative Example 1
Toners were produced in the same manner as in Example 1 except that the binder resin used in step 1 was changed as shown in Table 3. Table 3 shows the physical characteristics of the obtained toner.

Examples 6 and 7 and Comparative Example 3
In step 4, when the toner particle dispersion liquid at 60 ° C. is mixed with deionized water at 100 ° C. and heated to 93 ° C., the heating rate is 40 ° C./min, 20 ° C./min, or 10 ° C./min. Toner was obtained in the same manner as in Example 1 except that deionized water was added to the toner particle dispersion. Table 3 shows the physical characteristics of the obtained toner.

Comparative Example 2
Toner was obtained in the same manner as in Example 1 except that steps 3 and 4 were carried out as follows. Table 3 shows the physical characteristics of the obtained toner.

(Step 3)
After mixing 10.7 g (0.016 mol) of amphoteric surfactant (lauryldimethylamine oxide (Anchtor 20N, manufactured by Kao Co., Ltd., active ingredient 35% by mass)) and 321 g of deionized water in a 5 liter separable flask, 150 g of toner particles were added, and the mixture was stirred at 25 ° C. After the toner particles are sufficiently dispersed, 28% by mass of an anionic surfactant (Na salt of β-naphthalene sulfonic acid formarin condensate (Demor N, manufactured by Kao Co., Ltd., 100% active ingredient)) is added to deionized water. To 268 g (0.025 mol) of the diluted aqueous solution was added. Further, 3000 g of deionized water was added to adjust the toner particle concentration to 4% by mass, and the temperature was raised to 60 ° C. (system temperature) while dispersing the toner particles by stirring, and the toner particle dispersion was kept at the same temperature.

(Step 4)
Then, the toner particle dispersion was heated to 93 ° C. at a heating rate of 1 ° C./min.

Test Example 1 [Low temperature fixability]
High-quality paper "J paper A4 size" with 100 g of toner mounted on a commercially available printer "HL-L2360DN" (manufactured by Brother Industries, Ltd.) and a solid image with a toner adhesion of 0.40 ± 0.03 mg / cm ² on paper. (Made by Fuji Xerox Co., Ltd.) left a margin of 5 mm from the top edge of A4 paper, and output it with a length of 50 mm without fixing.
Next, the same printer in which the fuser was modified to have a variable temperature was prepared, the temperature of the fuser was set to 150 ° C., and the toner was fixed in the A4 vertical direction at a speed of 2 seconds per sheet to obtain a printed matter.
In the same manner, the temperature of the fuser was raised by 5 ° C. to fix the toner, and a printed matter was obtained.
From the top margin of the printed image to the solid image, lightly paste the mending tape "Scotch (registered trademark) Mending Tape 810" (manufactured by Sumitomo 3M Co., Ltd., width 18 mm) cut to a length of 50 mm. After attaching, a 500 g cylindrical weight (contact area: 157 mm ² ) was placed and pressed once back and forth at a speed of 10 mm / s. Then, the attached tape was peeled off from the lower end side at a peeling angle of 180 ° and a speed of 10 mm / s to obtain a printed matter after the tape was peeled off. 30 sheets of high-quality paper "J Paper A4 size" (manufactured by Fuji Xerox Co., Ltd.) are laid under the printed matter before and after the tape is applied, and the reflected image density of the fixed image part before and after the tape is attached to each printed matter is measured. , Colorimeter "SpectroEye" (Made by GretagMacbeth, light emission conditions; standard light source D ₅₀ , observation field 2 °, density standard DINNB, absolute white standard), and fixed according to the following formula from each reflected image density. The rate was calculated.
Retention rate (%) = (reflection image density after tape peeling / reflection image density before tape application) x 100
The lowest temperature at which the fixing rate was 90% or more was defined as the lowest fixing temperature. The results are shown in Table 3.

Test Example 2 [Transcribability]
A 100 g toner was mounted on a commercially available printer "HL-L2360DN" (manufactured by Brother Industries, Ltd.), and a solid image with a toner adhesion of 0.40 mg / cm ² was output. The toner developed on the photoconductor is transferred to high-quality paper "J paper A4 size" (manufactured by Fuji Xerox Co., Ltd.), the machine is stopped when the transfer to half of A4 is performed, and the surface of the photoconductor after transfer is transparent. The mending tape "Scotch (registered trademark) Mending Tape 810-3-18" (manufactured by Sumitomo 3M Co., Ltd.) was attached, and the transfer residual toner on the surface of the photoconductor was collected.
Attach the reference mending tape and the mending tape from which the transfer residual toner was collected on unused J paper, place it on 30 sheets of the same paper, and place a colorimeter (Gretag-Macbeth, "Spectro Eye"). ) Was used, the standard light source D ₅₀ , the observation field of view was 2 °, and the whiteness of the reference mending tape was used as the white reference, and the colors of CIE L ^* a ^* b ^* were measured. After that, the CIE L ^* a ^* b ^* of the mending tape from which the transfer residual toner was collected is measured, the color difference ΔE = (ΔL ^{* 2} + Δa ^{* 2} + Δb ^{* 2} ) ^1/2 from the reference is obtained, and the value is calculated. It was left as a transfer residue. The results are shown in Table 3. The smaller the value of ΔE, the smaller the transfer residue and the better the transferability.

From the above results, it can be seen that the toners obtained in Examples 1 to 7 have good low-temperature fixability, high circularity, and good transferability.
On the other hand, the toner of Comparative Example 1 which does not use the crystalline polyester resin lacks low-temperature fixability, and the toners of Comparative Examples 2 and 3 having a slow temperature rise rate of the toner particle dispersion have a low circularity. , It can be seen that it lacks transferability.

The toner obtained by the method of the present invention is suitably used for developing a latent image formed by an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

Claims (5)

Step 1. Melting and kneading a mixture containing a binder resin containing a crystalline polyester resin and an amorphous polyester resin, a colorant, and a mold release agent 1. The obtained kneaded product is crushed, classified, and toner particles. Step 2, the obtained toner particles are dispersed in an aqueous medium in the presence of a surfactant to obtain a toner particle dispersion liquid, and the obtained toner particle dispersion liquid is heated at a temperature rise rate of 15 ° C./min. A method for producing toner, which comprises the step 4 of heating as described above, wherein the average circularity of the obtained toner is 0.965 or more. The method for producing a toner according to claim 1, wherein the surfactant is at least one selected from the group consisting of anionic surfactants, cationic surfactants, and amphoteric surfactants. The method for producing a toner according to claim 1 or 2, wherein the temperature of the toner particle dispersion obtained in step 3 is the glass transition temperature of the amorphous polyester resin + 10 ° C. or lower. The method for producing a toner according to any one of claims 1 to 4, wherein step 4 is a step of mixing the toner particle dispersion with an aqueous medium having a temperature higher than that of the toner particle dispersion. The method for producing a toner according to claim 4, wherein the temperature of the aqueous medium to be mixed with the toner particle dispersion is 90 ° C. or higher.