Method for producing electrostatic charge image developing toner

Abstract

To provide a method for manufacturing an electrostatic charge image developing toner which exhibits excellent low-temperature fixability even in high-speed printing.SOLUTION: A method for producing a toner for electrostatic image development includes a step of melt-kneading at least a crystalline vinyl resin C, an amorphous resin A, and a release agent using an open-roller type kneader, and a step of pulverizing the kneaded product obtained in the previous step.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a toner for developing electrostatic images, which is used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like. [Background technology]

[0002] With the development of electrophotographic systems, there is a demand for electrostatic image developing toners (hereinafter simply referred to as "toners") that have low-temperature fixability and can handle even faster printing, for example, high-speed printing of about 0.5 to 1.0 seconds per A4 portrait sheet.

[0003] Known binder resins (binders) that have a significant effect on the properties of toner include polyester resins, vinyl resins, epoxy resins, polyurethane resins, polyamide resins, etc. Among these, vinyl resins and polyester resins have recently been widely used because they are easy to balance between charge retention rate and fixability.

[0004] Patent Document 1 discloses a toner binder containing an amorphous vinyl resin and a crystalline vinyl resin, with the aim of providing an excellent toner binder that satisfies requirements such as heat-resistant storage stability and charge retention rate while maintaining low-temperature fixability and hot offset resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-152637 Summary of the Invention [Problem to be solved by the invention]

[0006] However, further improvement is required in terms of low-temperature fixability that can be used for high-speed printing.

[0007] The present invention relates to a method for producing a toner for developing electrostatic images that exhibits excellent low-temperature fixability even during high-speed printing. [Means for solving the problem]

[0008] The present invention relates to a method for producing a toner for developing electrostatic images, which includes a step of melt-kneading at least a crystalline vinyl resin C, an amorphous resin A, and a release agent using an open-roll kneader, and a step of pulverizing the kneaded product obtained in the step. [Effects of the Invention]

[0009] The method of the present invention provides a toner for developing electrostatic images that exhibits excellent low-temperature fixability even during high-speed printing. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention has a major feature in that an open-roll kneader is used in the melt-kneading step when producing a toner for developing electrostatic images containing a crystalline vinyl resin, an amorphous resin, and a release agent. The reason why the method of the present invention enables a toner for developing electrostatic images with excellent low-temperature fixability even during high-speed printing is not clear, but is presumed to be as follows.

[0011] Crystalline vinyl resin is an effective resin for low-temperature fixability, but because it is hydrophobic, when used in combination with a similarly hydrophobic release agent, the interaction between the crystalline vinyl resin and the release agent during kneading increases viscosity, increasing shear and improving kneadability, allowing the crystalline vinyl resin to be finely dispersed in the amorphous resin. When melt-mixing is performed using a twin-screw extruder, the twin-screw extruder is a closed-type mixer, and the temperature of the mixture during mixing becomes much higher than the externally set temperature, which causes the interaction between the crystalline vinyl resin and the release agent to disappear, preventing improvement in the dispersibility of the crystalline vinyl resin. In contrast, an open-roll kneader is an open-type kneader, and by appropriately adjusting the roll conditions, it is possible to easily prevent an excessive temperature rise of the kneaded product during kneading and when cooling immediately after kneading. Therefore, by maintaining the interaction between the crystalline vinyl resin and the release agent even during kneading, it is possible to apply sufficient shear to the kneaded product, and the dispersibility of the crystalline vinyl resin in the amorphous resin is improved. As a result of the above, it is believed that by using a crystalline vinyl resin and a release agent in combination and kneading them in an open-roll kneader, the thermal response during toner fixing is improved, and therefore a toner for developing electrostatic images with excellent low-temperature fixing properties at high speeds can be obtained.

[0012] The method for producing the toner of the present invention includes the following melt-kneading step and pulverizing step.

[0013] The melt-kneading step is a step of melt-kneading at least the crystalline vinyl resin C, the amorphous resin A, and the release agent using an open-roll kneader.

[0014] From the viewpoint of enhancing crystallinity, the crystalline vinyl resin C is preferably an addition polymer of raw material monomers containing a (meth)acrylic acid alkyl ester L having a long-chain alkyl group. In this specification, "(meth)acrylic acid alkyl ester" means an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester.

[0015] The carbon number of the long-chain alkyl group in the (meth)acrylic acid alkyl ester L is preferably 10 or more, more preferably 12 or more, and from the viewpoint of high-speed, low-temperature fixability, is preferably 36 or less, more preferably 30 or less. The carbon number of the alkyl ester refers to the number of carbon atoms derived from the alcohol component constituting the ester.

[0016] Examples of the (meth)acrylic acid alkyl ester L include (iso)decyl (meth)acrylate, (iso)stearyl (meth)acrylate, (iso)behenyl (meth)acrylate, etc. In this specification, "(iso)" means that it includes both the case where this group is present and the case where it is not present, and when this group is not present, it means that it is normal.

[0017] The content of the (meth)acrylic acid alkyl ester L in the raw material monomers is preferably 10 mol% or more, more preferably 25 mol% or more, even more preferably 45 mol% or more, and is preferably 80 mol% or less, more preferably 70 mol% or less, even more preferably 60 mol% or less.

[0018] From the viewpoint of chargeability, the raw material monomer of the crystalline vinyl resin C preferably further contains a styrene compound and / or (meth)acrylic acid. In this specification, "(meth)acrylic acid" means acrylic acid and / or methacrylic acid.

[0019] Examples of the styrene compound include styrene and styrene derivatives such as α-methylstyrene and vinyltoluene, and among these, styrene is preferred.

[0020] The content of the styrene compound in the raw material monomer is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and preferably 60 mol% or less, more preferably 50 mol% or less, even more preferably 40 mol% or less.

[0021] The content of (meth)acrylic acid in the raw material monomers is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and preferably 60 mol% or less, more preferably 50 mol% or less, even more preferably 30 mol% or less.

[0022] The raw material monomers may include (meth)acrylic acid alkyl esters having an alkyl group having 9 or less carbon atoms; nitrile group-containing monomers such as acrylonitrile, methacrylonitrile, and methacrylonitrile in which the methyl group is replaced with an alkyl group having 2 to 16 carbon atoms; ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyl compounds such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenic monocarboxylic acid esters such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone.

[0023] The addition polymerization reaction of the raw material monomers of the crystalline vinyl resin C can be carried out by a conventional method such as radical polymerization, anionic polymerization, or cationic polymerization in the presence of, for example, a polymerization initiator, a chain transfer agent, a crosslinking agent, etc., in the presence of an organic solvent or in the absence of a solvent.

[0024] Examples of the polymerization initiator include organic peroxides such as dibutyl peroxide, dicumyl peroxide, and di-tert-butyl peroxide, and azo compounds such as 2,2'-azobis(2,3-dimethylvaleronitrile) and azobisisobutyronitrile.

[0025] The amount of the polymerization initiator used is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, based on 100 parts by mass of the raw material monomer.

[0026] As the organic solvent, xylene, toluene, methyl ethyl ketone, acetone, tetrahydrofuran, etc. can be used.

[0027] When the (meth)acrylic acid alkyl ester L is solid at room temperature, such as behenyl acrylate or stearyl acrylate, it is preferable to heat it in an organic solvent in advance to dissolve it, and then subject it to the addition polymerization reaction. The organic solvent is not particularly limited as long as it dissolves the (meth)acrylic acid alkyl ester L, and examples thereof include tetrahydrofuran, xylene, and toluene.

[0028] The amount of the organic solvent used is preferably 10 parts by mass or more and 400 parts by mass or less per 100 parts by mass of the raw material monomer.

[0029] The reaction temperature cannot be determined in general because it differs depending on the types of raw material monomers, polymerization initiator, and organic solvent, but is generally preferably 110° C. or higher, more preferably 140° C. or higher, and preferably 200° C. or lower, more preferably 170° C. or lower. However, when using a solvent having a boiling point lower than the above temperatures, such as tetrahydrofuran or toluene, to dissolve the (meth)acrylic acid alkyl ester L in an organic solvent, it is preferable to carry out the reaction at a temperature lower than the boiling point of the solvent.

[0030] The softening point of the crystalline vinyl resin C is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 55°C or higher from the viewpoint of storage stability, and is preferably 90°C or lower, more preferably 80°C or lower, and even more preferably 75°C or lower from the viewpoint of low-temperature fixability at high speed.

[0031] The crystallinity of a resin is expressed by the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, that is, the crystallinity index defined as the value of [softening point / maximum endothermic peak temperature]. The crystallinity index of the crystalline resin is 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, an amorphous resin is a resin in which no endothermic peak is observed, or if an endothermic peak is observed, the resin has a crystallinity index of more than 1.4, preferably more than 1.5, more preferably 1.6 or more, or less than 0.6, preferably 0.5 or less. The crystallinity of a resin can be adjusted by the types and ratios of raw material monomers, and production conditions (e.g., reaction temperature, reaction time, cooling rate), etc. The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. For crystalline resins, the maximum endothermic peak temperature is the melting point.

[0032] The melting point of the crystalline vinyl resin C is preferably 40°C or higher, more preferably 45°C or higher, and even more preferably 50°C or higher from the viewpoint of storage stability, and is preferably 90°C or lower, more preferably 85°C or lower, and even more preferably 80°C or lower from the viewpoint of low-temperature fixability at high speed.

[0033] The content of crystalline vinyl resin C is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more, of the total amount of crystalline vinyl resin C and amorphous resin A, from the viewpoint of low-temperature fixability at high speeds, and is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

[0034] Examples of the amorphous resin A include amorphous vinyl resins, amorphous polyester resins, amorphous epoxy resins, amorphous polycarbonates, amorphous polyurethanes, and composite resins containing two or more of these resins. Among these, from the viewpoint of low-temperature fixability, amorphous vinyl resins, amorphous polyester resins, and composite resins of amorphous polyester resins and amorphous vinyl resins are preferred, and amorphous vinyl resins are more preferred.

[0035] As the amorphous vinyl resin, from the viewpoint of enhancing amorphousness, a styrene-based resin which is an addition polymer of a raw material monomer containing a styrene compound is preferred, and a styrene-acrylic resin which is an addition polymer of a raw material monomer containing a styrene compound and a (meth)acrylic acid alkyl ester S having a short-chain alkyl group is more preferred.

[0036] The styrene compound is the same as the styrene compound in the crystalline vinyl resin C.

[0037] The content of the styrene compound in the raw material monomer is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 75 mol% or more, and preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less.

[0038] The carbon number of the short-chain alkyl group of the (meth)acrylic acid alkyl ester S is 1 or more, preferably 2 or more, more preferably 3 or more, and from the viewpoint of storage stability, is preferably 10 or less, more preferably 7 or less.

[0039] Examples of the (meth)acrylic acid alkyl ester S include methyl (meth)acrylate, ethyl (meth)acrylate, (iso)propyl (meth)acrylate, (iso)butyl (meth)acrylate, (iso)hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and (iso)octyl (meth)acrylate.

[0040] The content of the (meth)acrylic acid alkyl ester S in the raw material monomers is preferably 3 mol% or more, more preferably 7 mol% or more, even more preferably 10 mol% or more, and preferably 30 mol% or less, more preferably 25 mol% or less, even more preferably 20 mol% or less.

[0041] The raw material monomers may include (meth)acrylic acid alkyl esters other than (meth)acrylic acid alkyl ester S; nitrile group-containing monomers such as acrylonitrile, methacrylonitrile, and methacrylonitrile in which the methyl group is replaced with an alkyl group having from 2 to 16 carbon atoms; ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyl compounds such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenic monocarboxylic acid esters such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone.

[0042] Furthermore, the raw material monomers may contain a polymerizable crosslinking monomer from the viewpoint of adjusting the softening point.

[0043] The polymerizable crosslinking monomer is preferably a divinyl monomer, and examples thereof include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; di(meth)acrylic acid esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; and other divinyl compounds such as N,N-divinylaniline and divinyl ether.

[0044] Like the crystalline vinyl resin C, the amorphous vinyl resin can also be obtained by addition polymerization of raw material monomers.

[0045] The amorphous polyester resin is preferably 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.

[0046] Examples of the alkylene oxide adduct of bisphenol A include an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A, and are represented by the formula (I):

[0047] [ka]

[0048] (wherein OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y are the average number of moles of alkylene oxide added and are each 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.) A compound represented by the following formula is preferred.

[0049] From the viewpoint of low-temperature fixability, the content of the alkylene oxide adduct of bisphenol A in the alcohol component 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, but 100 mol% or less.

[0050] Examples of other alcohol components include aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, tri- or higher hydric alcohols such as trimethylolpropane, and the like.

[0051] Examples of aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0052] The content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 60 mol % or more, more preferably 70 mol % or more, and 100 mol % or less.

[0053] Examples of other carboxylic acid components include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with a hydrocarbon group, 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 having 1 to 3 carbon atoms.

[0054] The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monocarboxylic acid compound, as appropriate.

[0055] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol component and carboxylic acid component.

[0056] The equivalent ratio of the carboxyl groups of the carboxylic acid component to the hydroxyl groups of the alcohol component (COOH groups / OH groups) is preferably 0.8 or more, more preferably 0.9 or more, from the viewpoint of charging stability, and is preferably 1.2 or less, more preferably 1.1 or less, from the viewpoint of low-temperature fixability.

[0057] The amorphous polyester resin can be produced, for example, by polycondensing an alcohol component and a carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and optionally in the presence of a cocatalyst, a polymerization inhibitor, etc., at a temperature of preferably 160°C or higher, more preferably 200°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

[0058] Examples of esterification catalysts include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(triethanolaminate) and titanium dihydroxybis(triethanolaminate). The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 1 part by mass or less, per 100 parts by mass of the alcohol component and the carboxylic acid component combined. Examples of promoters for the esterification catalyst include gallic acid. The amount of the promoter used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.1 parts by mass or less, per 100 parts by mass of the alcohol component and the carboxylic acid component combined. Examples of polymerization inhibitors include tert-butylcatechol. 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, more preferably 0.1 part by mass or less, relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0059] In the present invention, the polyester resin may be modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins grafted or blocked with phenol, urethane, epoxy, or the like, by the methods described in JP-A Nos. 11-133668, 10-239903, and 8-20636. Among the modified polyester resins, urethane-modified polyester resins in which polyester resins are urethane-extended with a polyisocyanate compound are preferred.

[0060] The amorphous polyester resin in the composite resin is the same as the amorphous polyester resin described above, and the amorphous vinyl resin is preferably a styrene-based resin which is an addition polymer of raw material monomers containing a styrene compound.

[0061] The content of the styrene compound, preferably styrene, in the raw material monomers of the styrene-based resin is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more from the viewpoint of storage stability, and is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 90% by mass or less from the viewpoint of low-temperature fixability.

[0062] The styrene-based resin may also contain, as a raw material monomer, a (meth)acrylic acid alkyl ester having an alkyl group with 7 or more carbon atoms. Examples of the (meth)acrylic acid alkyl ester include 2-ethylhexyl (meth)acrylate, (iso)octyl (meth)acrylate, (iso)decyl (meth)acrylate, and (iso)stearyl (meth)acrylate. It is preferable to use one or more of these.

[0063] The number of carbon atoms in the alkyl group in the (meth)acrylic acid alkyl ester as a raw material monomer for the styrene-based resin is preferably 7 or more, more preferably 8 or more, from the viewpoint of improving the low-temperature fixability of the toner, and is preferably 18 or less, more preferably 12 or less.

[0064] The raw material monomers for styrene-based resins may include raw material monomers other than styrene compounds and (meth)acrylic acid alkyl esters, for example, nitrile group-containing monomers such as acrylonitrile, methacrylonitrile, and methacrylonitrile in which a methyl group is substituted with an alkyl group having from 2 to 16 carbon atoms; ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenic monocarboxylic acid esters such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone.

[0065] The raw material monomers of the styrene-based resin can also be addition polymerized in the same manner as the crystalline vinyl resin C.

[0066] The composite resin is preferably a resin in which an amorphous polyester resin and an amorphous vinyl resin are bonded together, and more preferably a resin in which an amorphous polyester resin and an amorphous vinyl resin are chemically bonded together via a bireactive monomer that can react with both the raw material monomers of the amorphous polyester resin and the raw material monomers of the amorphous vinyl resin.

[0067] The bireactive monomer is preferably a compound having at least one functional group selected from the group consisting of hydroxyl, carboxyl, epoxy, primary amino, and secondary amino groups, preferably a hydroxyl and / or carboxyl group, more preferably a carboxyl group, and an ethylenically unsaturated bond in the molecule, more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid, and maleic anhydride, and from the viewpoint of the reactivity of polycondensation reactions and addition polymerization reactions, even more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, and fumaric acid. However, when used together with a polymerization inhibitor, a polycarboxylic acid compound having an ethylenically unsaturated bond, such as fumaric acid, functions as a raw material monomer for the amorphous polyester resin. In this case, fumaric acid or the like is not a bireactive monomer but a raw material monomer for the amorphous polyester resin.

[0068] The amount of the bireactive monomer used is preferably 1 mol or more, more preferably 2 mol or more, relative to 100 mol of the total alcohol components of the amorphous polyester resin, from the viewpoint of increasing the dispersibility of the amorphous vinyl resin and the amorphous polyester resin and improving the dispersibility of the raw materials in the toner, and is preferably 30 mol or less, more preferably 20 mol or less, and even more preferably 10 mol or less, from the viewpoint of improving the low-temperature fixability of the toner.

[0069] Specifically, the composite resin is preferably produced by the following method: When a bireactive monomer is used, the bireactive monomer is preferably used together with a raw material monomer of an amorphous vinyl resin, from the viewpoint of improving the dispersibility of the raw material in the toner and the low-temperature fixability.

[0070] (i) A method in which step (A) of polycondensation reaction using raw material monomers for an amorphous polyester resin is followed by step (B) of addition polymerization reaction using raw material monomers for an amorphous vinyl resin. In this method, step (A) is carried out under reaction temperature conditions suitable for polycondensation reaction, and then the reaction temperature is lowered and step (B) is carried out under temperature conditions suitable for addition polymerization reaction. It is preferable that the raw material monomers for the amorphous vinyl resin are added to the reaction system at a temperature suitable for the addition polymerization reaction. When a bireactive monomer is used together with the raw material monomers for the amorphous vinyl resin, the bireactive monomer undergoes addition polymerization reaction and also reacts with the amorphous polyester resin. After step (B), the reaction temperature is raised again, and if necessary, a raw material monomer of the amorphous polyester resin having a valence of three or more, which serves as a crosslinking agent, is added to the polymerization system, thereby further promoting the polycondensation reaction of step (A) and the reaction with the bireactive monomer.

[0071] (ii) A method in which step (B) of an addition polymerization reaction using raw material monomers for an amorphous vinyl resin is followed by step (A) of a polycondensation reaction using raw material monomers for an amorphous polyester resin. In this method, step (B) is carried out under reaction temperature conditions suitable for an addition polymerization reaction, and then the reaction temperature is raised to carry out the polycondensation reaction in step (A) under temperature conditions suitable for a polycondensation reaction. When a bireactive monomer is used together with the raw material monomers for the amorphous vinyl resin, the bireactive monomer participates in both the addition polymerization reaction and the polycondensation reaction. The raw material monomers for the amorphous polyester resin may be present in the reaction system during the addition polymerization reaction, or may be added to the reaction system under temperature conditions suitable for the polycondensation reaction. In the former case, the progress of the polycondensation reaction can be controlled by adding an esterification catalyst at a temperature suitable for the polycondensation reaction.

[0072] (iii) A method in which the step (A) of polycondensation reaction of raw material monomers for the amorphous polyester resin and the step (B) of addition polymerization reaction of raw material monomers for the amorphous vinyl resin are carried out under conditions in which the reactions proceed in parallel. In this method, it is preferable to carry out steps (A) and (B) in parallel under reaction temperature conditions suitable for the addition polymerization reaction, raise the reaction temperature, and, if necessary, add a trivalent or higher amorphous polyester resin raw material monomer that serves as a crosslinker to the polymerization system under temperature conditions suitable for the polycondensation reaction, and then further carry out the polycondensation reaction of step (A). In this case, under temperature conditions suitable for the polycondensation reaction, it is also possible to add a polymerization inhibitor and proceed with just the polycondensation reaction. When a bireactive monomer is used, the bireactive monomer participates in both the addition polymerization reaction and the polycondensation reaction.

[0073] In the above method (i), a prepolymerized amorphous polyester resin may be used instead of the polycondensation reaction in step (A). In the above method (iii), when the reaction is carried out under conditions in which steps (A) and (B) proceed in parallel, a mixture containing raw material monomers for the amorphous vinyl resin may be added dropwise to a mixture containing raw material monomers for the amorphous polyester resin to cause the reaction.

[0074] The above methods (i) to (iii) are preferably carried out in the same container.

[0075] The mass ratio of the amorphous polyester resin to the amorphous vinyl resin in the composite resin (amorphous polyester resin / amorphous vinyl resin) is preferably 60 / 40 or more, more preferably 70 / 30 or more, and even more preferably 75 / 25 or more, from the viewpoint of low-temperature fixability. Furthermore, from the viewpoint of improving the dispersibility of the raw materials in the toner, it is preferably 98 / 2 or less, more preferably 95 / 5 or less, and even more preferably 90 / 10 or less. In the above calculation, the mass of the amorphous polyester resin is the mass of the raw material monomers of the amorphous polyester resin used, minus the amount of reaction water (calculated value) dehydrated by the polycondensation reaction. The amount of the bireactive monomer is included in the amount of raw material monomers of the amorphous polyester resin. The amount of the amorphous vinyl resin is the total amount of the raw material monomers of the amorphous vinyl resin and the polymerization initiator.

[0076] The softening point of the amorphous resin A is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher from the viewpoint of charging stability, and is preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 155°C or lower from the viewpoint of low-temperature fixability.

[0077] From the viewpoint of low-temperature fixability and fixation width, the amorphous resin A may be composed of resins with different softening points. The difference in softening point between the two resins is preferably 10°C or more, more preferably 15°C or more, and is preferably 50°C or less, more preferably 35°C or less.

[0078] Furthermore, the softening point of the amorphous resin A (resin AH) having a higher softening point is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher, from the viewpoint of fixing width, and is preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 155°C or lower, from the viewpoint of low-temperature fixability.

[0079] The softening point of the amorphous resin A (resin AL) having the lower softening point is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher from the viewpoint of charging stability, and is preferably 130°C or lower, more preferably 125°C or lower, and even more preferably 120°C or lower from the viewpoint of low-temperature fixability.

[0080] The number average molecular weight of the amorphous resin AH is preferably 1,000 or more, more preferably 1,500 or more, from the viewpoint of storage stability, and is preferably 8,000 or less, more preferably 5,000 or less, from the viewpoint of low-temperature fixability at high speed.

[0081] The weight average molecular weight of the amorphous resin AH is preferably 30,000 or more, more preferably 50,000 or more, from the viewpoint of storage stability, and is preferably 1,000,000 or less, more preferably 500,000 or less, from the viewpoint of low-temperature fixability at high speed.

[0082] The number average molecular weight of the amorphous resin AL is preferably 1,000 or more, more preferably 1,500 or more, from the viewpoint of storage stability, and is preferably 8,000 or less, more preferably 5,000 or less, from the viewpoint of low-temperature fixability at high speed.

[0083] The weight average molecular weight of the amorphous resin AL is preferably 3,000 or more, more preferably 5,000 or more, from the viewpoint of storage stability, and is preferably 500,000 or less, more preferably 200,000 or less, from the viewpoint of low-temperature fixability at high speed.

[0084] The mass ratio of resin AH to resin AL (resin AH / resin AL) is preferably 10 / 90 or more, more preferably 20 / 80 or more, even more preferably 30 / 70 or more, and is preferably 90 / 10 or less, more preferably 80 / 20 or less, even more preferably 75 / 25 or less.

[0085] The glass transition temperature of the amorphous resin A is preferably 40°C or higher, more preferably 50°C or higher, from the viewpoint of storage stability, and is preferably 80°C or lower, more preferably 70°C or lower, from the viewpoint of low-temperature fixability.

[0086] When the amorphous resin A is an amorphous polyester resin or a composite resin containing an amorphous polyester resin, the acid value is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, from the viewpoint of charging stability, and is preferably 30 mgKOH / g or less, more preferably 25 mgKOH / g or less, from the viewpoint of storage stability.

[0087] From the viewpoint of low-temperature fixability at high speeds, the content of amorphous resin A is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, of the total amount of crystalline vinyl resin C and amorphous resin A, and is preferably 97% by mass or less, more preferably 95% by mass or less, even more preferably 93% by mass or less.

[0088] From the viewpoint of low-temperature fixability at high speeds, the mass ratio of crystalline vinyl resin C to amorphous resin A (crystalline vinyl resin C / amorphous resin A) is preferably 3 / 97 or more, more preferably 5 / 95 or more, even more preferably 7 / 93 or more, and is preferably 30 / 70 or less, more preferably 25 / 75 or less, even more preferably 20 / 80 or less.

[0089] In the present invention, the crystalline vinyl resin C and the amorphous resin A are used as binder resins.

[0090] The total content of the crystalline vinyl resin C and the amorphous resin A in the binder resin is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, but 100% by mass or less.

[0091] Examples of other resins include polyamide resins, epoxy resins, polycarbonate resins, polyurethane resins, and composite resins containing two or more of these resins.

[0092] The content of the binder resin in the toner is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 99.5% by mass or less, more preferably 95% by mass or less, even more preferably 93% by mass or less.

[0093] Examples of the release agent include hydrocarbon waxes such as polypropylene wax, polyethylene wax, ethylene-propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and oxides thereof; carnauba wax, montan wax, and deoxidized waxes thereof; ester waxes such as fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts, which may be used alone or in combination. Among these, ester waxes are preferred from the viewpoint of high-speed, low-temperature fixability.

[0094] The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of toner transferability, and is preferably 160°C or lower, more preferably 140°C or lower, even more preferably 120°C or lower, and even more preferably 110°C or lower, from the viewpoint of low-temperature fixability.

[0095] The content of the release agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, relative to 100 parts by mass of the binder resin, from the viewpoints of the low-temperature fixability and offset resistance of the toner and the dispersibility in the binder resin, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less.

[0096] Examples of raw materials that can be subjected to melt-kneading together with the crystalline vinyl resin C, the amorphous resin A, and the release agent include additives such as colorants, release agents, charge control agents, magnetic powders, flowability improvers, conductivity adjusters, reinforcing fillers such as fibrous substances, antioxidants, and cleaning improvers.

[0097] As the colorant, dyes, pigments, magnetic materials, etc. used as toner colorants can be used. Examples include carbon black, phthalocyanine blue, permanent brown FG, brilliant fast 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 the present invention, the toner may be either a black toner or a color toner.

[0098] From the viewpoint of improving the image density and low-temperature fixability of the toner, 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, relative to 100 parts by mass of the binder resin.

[0099] The charge control agent is not particularly limited, and may contain either a positively chargeable charge control agent or a negatively chargeable charge control agent.

[0100] Examples of positively chargeable charge control agents include nigrosine dyes such as "Nigrosine Base EX," "Oil Black BS," "Oil Black SO," "Bontron N-01," "Bontron N-04," "Bontron N-07," "Bontron N-09," "Bontron N-11," and "Bontron N-79" (all manufactured by Orient Chemical Industries Co., Ltd.); triphenylmethane dyes containing a tertiary amine as a side chain; quaternary ammonium salt compounds such as "Bontron P-51" (manufactured by Orient Chemical Industries Co., Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX Examples of suitable resins include polyamine resins such as "AFP-B" (manufactured by Orient Chemical Industries Co., Ltd.); imidazole derivatives such as "PLZ-2001" and "PLZ-8001" (both manufactured by Shikoku Chemical Industry Co., Ltd.); and styrene-acrylic resins such as "FCA-701PT" and "FCA-201-PS" (manufactured by Fujikura Chemical Industries Co., Ltd.).

[0101] Examples of negatively chargeable charge control agents include metal-containing azo dyes such as "Balifast 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 benzilic acid compounds such as "LR-147" and "LR-297" (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 VP434 (manufactured by Clariant), nitroimidazole derivatives, etc.; organometallic compounds, etc.

[0102] From the viewpoint of the charge stability of the toner, the amount of the 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, relative to 100 parts by mass of the binder resin.

[0103] In the melt-kneading step, the raw materials to be melt-kneaded are preferably premixed using a Henschel mixer or the like, and then fed to an open-roll kneader.

[0104] An open-roll kneader refers to a kneading machine in which the kneading section is open and not sealed, and the heat of kneading generated during melt kneading can be easily dissipated. The open-roll kneader used in the present invention is provided with a raw material supply port and a kneaded material discharge port provided along the axial direction of the rolls, and from the viewpoint of production efficiency, it is preferably a continuous open-roll kneader.

[0105] The open-roll kneader used in the present invention is preferably a kneader equipped with two rolls with different peripheral speeds, i.e., a roll with a high peripheral speed (high rotation roll) and a roll with a low peripheral speed (low rotation roll). In the present invention, from the viewpoint of dispersibility of the kneaded material, it is preferable that the high rotation roll functions as a heating roll and the low rotation roll functions as a cooling roll, that is, it is preferable that the set temperature of the high rotation roll is higher than that of the low rotation roll. When the set temperatures of the rolls on the raw material input side and the kneaded material discharge side are different, it is preferable that the set temperature of the high rotation roll is higher than that of the low rotation roll at least on the raw material input side, and it is more preferable that the set temperature of the high rotation roll is higher than that of the low rotation roll on both the raw material input side and the kneaded material discharge side.

[0106] The temperature of the rolls can be adjusted, for example, by the temperature of a heat medium passed through the inside of the rolls. The inside of each roll may be divided into two or more sections through which heat mediums of different temperatures are passed.

[0107] The temperature of the raw material inlet side of the high rotation roll is preferably 100° C. or higher, more preferably 120° C. or higher, and preferably 160° C. or lower, more preferably 150° C. or lower, from the viewpoint of reducing the mechanical force during melt-kneading and suppressing heat generation. From the same viewpoint, the temperature of the raw material inlet side of the low rotation roll is preferably 25° C. or higher, more preferably 40° C. or higher, and preferably 90° C. or lower, more preferably 80° C. or lower.

[0108] For both the high-speed rotation roll and the low-speed rotation roll, it is preferable that the temperature on the raw material input side is higher than that on the kneaded material discharge side, and the temperature difference between the raw material input side and the kneaded material discharge side is preferably 20°C or more, more preferably 30°C or more, from the viewpoint of preventing the kneaded material from detaching from the roll, reducing the mechanical force during melt kneading, and suppressing heat generation, and is preferably 60°C or less, more preferably 50°C or less.

[0109] The temperature of the raw material input side of the high rotation roll and the low rotation roll refers to the set temperature at the raw material input end, and the temperature of the kneaded material discharge side refers to the set temperature at the kneaded material discharge end.

[0110] From the viewpoint of reducing mechanical power during kneading and suppressing heat generation, 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 same viewpoint, 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. 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, more preferably 8 / 10 or less.

[0111] There are no particular limitations on the structure, size, material, etc. of each roll. The roll surface has grooves used for kneading, and the shape of these grooves may be linear, spiral, wavy, or uneven.

[0112] After the melt-kneading step, the resulting kneaded product is appropriately cooled to a pulverizable hardness and then subjected to the subsequent pulverization step. Here, "cooling" refers to cooling the kneaded product to 0°C to 50°C or to a temperature below the glass transition temperature of the binder resin in the kneaded product.

[0113] The pulverization step is a step of pulverizing the kneaded product obtained in the melt-kneading step.

[0114] In the pulverization step, the kneaded material may be pulverized to the desired particle size all at once or in stages. However, from the viewpoint of efficient and more uniform pulverization, it is preferable to carry out the pulverization in two stages: coarse pulverization and fine pulverization.

[0115] Examples of the crusher used for coarse crushing include a hammer mill, a cutter mill, an atomizer, and a rotoplex.

[0116] Examples of mills used for fine pulverization include jet mills such as counter jet mills, fluidized bed jet mills and collision plate jet mills, and mechanical mills.

[0117] The degree of pulverization is preferably adjusted appropriately depending on the particle size of the toner particles to be obtained.

[0118] After the pulverization step, a classification step is carried out as necessary.

[0119] Classifiers used for classification include air classifiers, inertial classifiers, sieve classifiers, etc. During the classification step, pulverized material removed due to insufficient pulverization may be subjected to the pulverization step again, and the pulverization step and classification step may be repeated as necessary.

[0120] In the present invention, from the viewpoint of further improving transferability, it is preferable to carry out a step of mixing the obtained toner particles with an external additive after the pulverization step or classification step.

[0121] 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 melamine-based resin fine particles and polytetrafluoroethylene resin fine particles, and two or more of these may be used in combination. Among these, silica is preferred, and from the viewpoint of toner transferability, hydrophobic silica that has been subjected to a hydrophobic treatment is more preferred.

[0122] Examples of hydrophobic treatment agents for hydrophobizing the surfaces of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazanes, silicone oils, aminosilanes, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0123] From the viewpoint of the chargeability, fluidity, and transferability of the toner, the average particle diameter of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and is preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 90 nm or less.

[0124] The external addition treatment by mixing the toner particles with the external additives can be carried out in accordance with a conventional method, and a mixer such as a Henschel mixer can be used.

[0125] From the viewpoint of the chargeability, fluidity, and transferability of the toner, the amount of the external additive used is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the toner particles before treatment with the external additive, and is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

[0126] The volume median particle size (D 50) is preferably 3 μm or more, more preferably 4 μm or more, and is preferably 15 μm or less, more preferably 10 μm or less. 50 ) means the particle size at which the cumulative volume frequency calculated by volume fraction is 50% starting from the smallest particle size. In addition, when the toner is treated with an external additive, the volume median particle size of the toner particles before treatment with the external additive is taken as the volume median particle size of the toner.

[0127] The toner obtained by the method of the present invention can be used as a toner for one-component development, or mixed with a carrier to form a two-component developer. [Example]

[0128] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Physical properties of resins and the like were measured by the following methods.

[0129] [Softening point of resin] Using a flow tester "CFT-500D" (Shimadzu Corporation), 1 g of sample is heated at a temperature increase rate of 6°C / min while applying a load of 1.96 MPa with the plunger, and extruding it from a nozzle 1 mm in diameter and 1 mm in length. The plunger depression distance of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[0130] [Maximum endothermic peak temperature of resin] Using a differential scanning calorimeter "Q-100" (TA Instruments Japan Co., Ltd.), weigh 0.01-0.02 g of sample into an aluminum pan, cool from room temperature (25°C) to 0°C at a rate of 10°C / min, and maintain at 0°C for 1 minute. Then, measure at a rate of 10°C / min. The temperature of the peak with the largest peak area among the observed endothermic peaks is taken as the maximum endothermic peak temperature. For crystalline resins, the maximum endothermic peak temperature is taken as the melting point.

[0131] [Glass transition temperature of resin] Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.01-0.02 g of sample is weighed into an aluminum pan, heated to 200°C, and cooled to 0°C at a rate of 10°C / min. The sample is then heated at a rate of 10°C / min, and the endothermic peak is measured. The glass transition temperature is the temperature at the intersection of an extension of the baseline below the maximum endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the peak apex.

[0132] [Acid value of resin] Measurement is performed based on the method of JIS K 0070:1992, except that the measurement solvent is changed from the ethanol and ether mixture specified in JIS K 0070 to a mixture of acetone and toluene (acetone:toluene = 1:1 (volume ratio)).

[0133] [Number average molecular weight and weight average molecular weight of resin] The number average molecular weight and weight average molecular weight are determined by gel permeation chromatography (GPC) according to the following method. (1) Preparation of sample solution The resin was dissolved in tetrahydrofuran to a concentration of 0.5 g / 100 mL, and then filtered through a fluororesin filter (manufactured by Sumitomo Electric Industries, Ltd., product name: FP-200) with a pore size of 2 μm to remove insoluble components, thereby obtaining a sample solution. (2) Molecular weight measurement Using the following measurement equipment and analytical column, tetrahydrofuran was used as the eluent at a flow rate of 1 mL per minute, and the column was stabilized in a thermostatic bath at 40°C. 100 μL of sample solution was injected into the column and the measurement was performed. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. The calibration curve used here included monodisperse polystyrene (Tosoh Corporation; 2.63 × 10) of several types with known molecular weights. 3 , 2.06×10 4 , 1.02 × 10 5 , manufactured by GL Sciences Inc.; 2.10 x 10 3 , 7.00 x 10 3 , 5.04×10 4) is used as a standard sample. Measuring device: CO-8010 (product name, manufactured by Tosoh Corporation) Analytical column: GMH XL +G3000H XL (All are product names, manufactured by Tosoh Corporation)

[0134] [Melting point of release agent] Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.02 g of sample was weighed into an aluminum pan, heated to 200°C at a rate of 10°C / min, and then cooled from 200°C to 0°C at a rate of 10°C / min. The sample was then heated at a rate of 10°C / min, the calorific value was measured, and the maximum endothermic peak temperature was taken as the melting point.

[0135] [Average particle size of external additives] The average particle size refers to the number-average particle size, and is calculated by measuring the particle sizes (average values ​​of major and minor axes) of 500 particles in a scanning electron microscope (SEM) photograph and averaging these values ​​by number.

[0136] [Volume median particle size of toner (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" (Beckman Coulter, Inc.) Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) Dispersion: Polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" (manufactured by Kao Corporation, HLB (Griffin) = 13.6) dissolved in the electrolyte to adjust the concentration to 5% by mass Dispersion conditions: 10 mg of the measurement sample was added to 5 mL of the dispersion, and the mixture was dispersed for 1 minute using an ultrasonic disperser (machine name: US-1 manufactured by SND Corporation, output: 80 W). 25 mL of electrolyte was then added, and the mixture was further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion. Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles could be measured in 20 seconds. Then, 30,000 particles were measured, and the volume median particle size (D 50 ) is found.

[0137] Resin manufacturing example 1 A 3-liter four-neck flask equipped with a thermometer, stainless steel stirrer, flow-through condenser, dropping funnel, and nitrogen inlet tube was charged with 400 g of xylene. The dropping funnel contained 902 g (8.7 mol) of styrene, 198 g (1.5 mol) of n-butyl acrylate, 45 g (0.35 mol) of divinylbenzene as a polymerizable crosslinking monomer, and 110 g of dibutyl peroxide as a radical polymerization initiator. Under a nitrogen atmosphere, the xylene was heated to 130°C with stirring, and the mixture in the dropping funnel was added dropwise over 1 hour. The mixture was then heated to 140°C and held at that temperature for 2 hours. The pressure in the flask was then further reduced to 8 kPa and held for 1 hour. The xylene was then removed at 200°C to obtain an amorphous vinyl resin (Resin AH1). The softening point of the obtained resin was 133°C, the maximum endothermic peak temperature was 60°C, the crystallinity index was 2.2, the glass transition temperature was 57°C, the number average molecular weight was 4,500, and the weight average molecular weight was 215,000.

[0138] Resin manufacturing example 2 A 3-liter four-neck flask equipped with a thermometer, stainless steel stirrer, flow-through condenser, dropping funnel, and nitrogen inlet tube was charged with 400 g of xylene. The dropping funnel contained 902 g (8.7 mol) of styrene, 198 g (1.5 mol) of n-butyl acrylate, and 110 g of dibutyl peroxide (radical polymerization initiator). Under a nitrogen atmosphere, the xylene was heated to 130 °C with stirring, and the mixture in the dropping funnel was added dropwise over 1 hour. The temperature was then raised to 140 °C and maintained at that temperature for 2 hours. The pressure in the flask was then reduced to 8 kPa and maintained at 8 kPa for 1 hour. The xylene was then removed at 200 °C to obtain an amorphous vinyl resin (Resin AL1). The resulting resin had a softening point of 106 °C, a maximum endothermic peak temperature of 62 °C, a crystallinity index of 1.7, a glass transition temperature of 53 °C, a number-average molecular weight of 5,000, and a weight-average molecular weight of 24,000.

[0139] Resin manufacturing example 3 The alcohol component, carboxylic acid component other than trimellitic anhydride, esterification catalyst, and co-catalyst shown in Table 1 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, stirrer, and thermocouple, and the mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. The temperature was then lowered to 210°C, and trimellitic anhydride shown in Table 1 was added. The mixture was reacted at 210°C for 1 hour, and then further reacted at 210°C under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, yielding an amorphous polyester resin (Resin AH2). The physical properties are shown in Table 1.

[0140] Resin manufacturing example 4 The raw material monomers for polyester resin other than trimellitic anhydride and fumaric acid, esterification catalyst, and cocatalyst shown in Table 1 were placed in a 5-liter four-neck flask equipped with a dehydration tube with a nitrogen inlet, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then subjected to polycondensation at 235°C for 6 hours. The temperature was then lowered to 160°C, and a mixture of the bireactive monomer, raw material monomers for styrene resin, and polymerization initiator was added dropwise over 1 hour using a dropping funnel. After the dropwise addition, the temperature was maintained at 160°C and the addition polymerization reaction was allowed to proceed for 1 hour. The temperature was then raised to 200°C and the pressure was reduced to 10 kPa for 1 hour. After the pressure was released, the temperature was lowered to 180°C, and the trimellitic anhydride, fumaric acid, and polymerization inhibitor shown in Table 1 were added. The mixture was then held at 180°C for 1 hour, after which the temperature was increased from 180°C to 210°C at a rate of 10°C / h and the reaction was carried out at 210°C for 1 hour. Furthermore, the reaction was continued at 210° C. under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, thereby obtaining an amorphous composite resin (Resin AH3).

[0141] Resin manufacturing example 5 The alcohol component, carboxylic acid components other than trimellitic anhydride and fumaric acid, esterification catalyst, and cocatalyst shown in Table 1 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, stirrer, and thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then subjected to polycondensation at 235°C for 6 hours. The temperature was then lowered to 180°C, and trimellitic anhydride, fumaric acid, and polymerization inhibitor shown in Table 1 were added. The mixture was then maintained at 180°C for 1 hour, after which the temperature was increased from 180°C to 210°C at a rate of 10°C / h and reacted at 210°C for 1 hour. The reaction was then continued at 210°C under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, yielding an amorphous polyester resin (Resin AH4). The physical properties are shown in Table 1.

[0142] Resin manufacturing example 6 The alcohol component, carboxylic acid component, esterification catalyst, and cocatalyst shown in Table 1 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, stirrer, and thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, followed by polycondensation at 235°C for 6 hours. The temperature was then lowered to 210°C, and the reaction was continued under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, yielding amorphous polyester resins (resins AL2 and AL4). The physical properties are shown in Table 1.

[0143] Resin manufacturing example 7 The raw material monomers for the polyester resin other than fumaric acid, the esterification catalyst, and the cocatalyst shown in Table 1 were placed in a 5-liter four-neck flask equipped with a dehydration tube with a nitrogen inlet, a stirrer, and a thermocouple. The flask was heated to 235°C under a nitrogen atmosphere and then subjected to polycondensation at 235°C for 6 hours. The temperature was then lowered to 160°C, and a mixture of the bireactive monomer, the raw material monomers for the styrene resin, and the polymerization initiator was added dropwise over 1 hour using a dropping funnel. After the addition, the temperature was maintained at 160°C and the addition polymerization reaction was allowed to proceed for 1 hour. The temperature was then raised to 200°C and the pressure was reduced to 10 kPa for 1 hour. After the pressure was released, the temperature was lowered to 180°C, and the fumaric acid and polymerization inhibitor shown in Table 1 were added. The flask was then held at 180°C for 1 hour, after which the temperature was increased from 180°C to 210°C at a rate of 10°C / h and the reaction was carried out at 210°C for 1 hour. Furthermore, the reaction was continued at 210° C. under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, thereby obtaining an amorphous composite resin (resin AL3).

[0144] [Table 1]

[0145] Resin manufacturing example 8 A 3-liter four-neck flask equipped with a thermometer, stainless steel stirrer, flow condenser, dropping funnel, and nitrogen inlet tube was charged with 400 g of tetrahydrofuran (THF). In a separate container, 350 g of THF and the vinyl resin raw material monomers and polymerization initiators shown in Table 2 were added, stirred, and mixed at 40°C, and then added to the dropping funnel. Under a nitrogen atmosphere, the THF was heated to 60°C with stirring, and the mixture in the dropping funnel was added dropwise over 1 hour. The temperature was then raised to 65°C and maintained at 65°C for 2 hours. The pressure in the flask was then reduced and maintained at 8 kPa for 1 hour. The THF was then removed at 65°C to obtain crystalline vinyl resins (Resins C1 to C3). Their physical properties are shown in Table 2.

[0146] Resin manufacturing example 9 A 3-liter four-neck flask equipped with a thermometer, stainless steel stirrer, flow-through condenser, dropping funnel, and nitrogen inlet tube was charged with 400 g of xylene. In a separate container, 350 g of xylene and the vinyl resin raw material monomers and polymerization initiators shown in Table 2 were added, stirred, and mixed at 40°C, and then added to the dropping funnel. Under a nitrogen atmosphere, the xylene was heated to 130°C with stirring, and the mixture in the dropping funnel was added dropwise over 1 hour. The temperature was then raised to 140°C and held at 140°C for 2 hours. The pressure in the flask was then reduced and held at 8 kPa for 1 hour. The xylene was then removed at 200°C to obtain a crystalline vinyl resin (Resin C4). Its physical properties are shown in Table 2.

[0147] Resin manufacturing example 10 A 3-liter four-neck flask equipped with a thermometer, stainless steel stirrer, flow-through condenser, dropping funnel, and nitrogen inlet tube was charged with 400 g of toluene. In a separate container, 350 g of toluene and the vinyl resin raw material monomers and polymerization initiators shown in Table 2 were added, stirred, and mixed at 40°C, and then added to the dropping funnel. Under a nitrogen atmosphere, the toluene was heated to 80°C with stirring, and the mixture in the dropping funnel was added dropwise over 1 hour. The temperature was then raised to 85°C and held at 85°C for 2 hours. The pressure in the flask was then reduced and held at 8 kPa for 1 hour. The toluene was then removed at 130°C to obtain a crystalline vinyl resin (Resin C5). Its physical properties are shown in Table 2.

[0148] [Table 2]

[0149] Examples 1, 3 to 11 100 parts by mass of the binder resin shown in Table 3, 5 parts by mass of a colorant "ECB-301" (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., phthalocyanine blue (PB15:3)), 6 parts by mass of a release agent "Carnauba Wax C1" (manufactured by Kato Yoko Co., Ltd., melting point: 83°C), and 0.5 parts by mass of a charge control agent "Bontron E-304" (manufactured by Orient Chemical Industries Co., Ltd.) were mixed in a Henschel mixer.

[0150] The resulting raw material mixture was fed to a continuous twin-open roll kneader "Kneedex" (manufactured by Nippon Coke and Engineering Co., Ltd.) using a table feeder and kneaded to obtain a kneaded product. The continuous twin-open roll kneader used here had a roll outer diameter of 0.14 m and an effective roll length of 0.8 m. The operating conditions were a rotation speed of the high-speed roll (front roll) of 75 r / min (circumferential speed 33 m / min), a rotation speed of the low-speed roll (rear roll) of 50 r / min (circumferential speed 22 m / min), and a roll gap of 0.1 mm. The heating and cooling medium temperatures within the rolls were set as follows: the temperature on the raw material inlet side of the high-speed roll was 150°C and the temperature on the kneaded material outlet side was 100°C; the temperature on the raw material inlet side of the low-speed roll was 65°C and the temperature on the kneaded material outlet side was 30°C. The raw material mixture was fed at a rate of 10 kg / h, and the average residence time was approximately 5 minutes.

[0151] The resulting kneaded product was cooled to 25°C and coarsely pulverized using a pulverizer "Rotoplex" (manufactured by Hosokawa Micron Corporation). A sieve with 2 mm openings was used to obtain a coarsely pulverized product with a particle size of 2 mm or less. It was then finely pulverized and subjected to upper limit classification (removal of coarse particles) using a counter jet mill "400AFG" (manufactured by Hosokawa Alpine Corporation). Furthermore, it was subjected to lower limit classification (removal of fine particles) using a classifier "TTSP" (manufactured by Hosokawa Alpine Corporation) to obtain a volume median particle size (D 50 ) toner particles of 7.0 μm were obtained.

[0152] 100 parts by mass of the obtained toner particles and 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) as external additives were mixed in a Henschel mixer at a rotation speed of 3000 r / min (circumferential speed: 32 m / sec) for 3 minutes to obtain a toner.

[0153] Example 2 A toner was obtained in the same manner as in Example 1, except that 6 parts by mass of "HNP-9" (paraffin wax, manufactured by Nippon Seiro Co., Ltd., melting point: 75°C) was used as the release agent instead of 6 parts by mass of "Carnauba Wax C1" (manufactured by Kato Yoko Co., Ltd., melting point: 83°C).

[0154] Comparative Examples 1 and 2 Toner was obtained in the same manner as in Example 1, except that the binder resins shown in Table 3 were used and melt-kneading was carried out using a twin-screw extruder "PCM-30" (manufactured by Ikegai Corporation) instead of the continuous two-open roll kneader. The operating conditions of the twin-screw extruder were a barrel set temperature of 100°C, a shaft rotation speed of 200 r / min (circumferential speed of shaft rotation of 0.30 m / sec), a mixture supply rate of 10 kg / h, and an average residence time of approximately 18 seconds.

[0155] Test Example [Low Temperature Fixability of Toner] (1) Low-temperature fixability at high speeds The toner was loaded into a copy machine "AR-505" (manufactured by Sharp Corporation) whose fixing unit was modified to enable fixing outside the machine, and a printout was obtained in an unfixed state (print area: 2 cm × 12 cm, adhesion amount: 0.5 mg / cm 2 ). The toner was then fixed in an A4 portrait orientation at 0.8 seconds per sheet using a fixing machine adjusted to a total fixing pressure of 40 kgf, with the fixing machine temperature at 100°C. The toner was fixed in the same manner, yielding a printed product. The toner was fixed by increasing the fixing machine temperature by 5°C increments, yielding a printed product. A mending tape, "Scotch (registered trademark) Mending Tape 810" (3M Japan, width: 18 mm), was applied to the image portion of the resulting printed product. The print was then passed through a fixing roller set at 30°C, separate from the fixing roller of the fixing machine, and the tape was then peeled off. The optical reflection density before and after tape application was measured using a reflection densitometer, "RD-915" (X-Rite). The temperature of the fixing roll at which the ratio (after peeling / before application x 100) first exceeded 90% was defined as the minimum fixing temperature. The results are shown in Table 3. A lower minimum fixing temperature indicates better low-temperature fixability. The fixing paper used was "CopyBond SF-70NA" (manufactured by Sharp Corporation, 75 g / m 2 ) was used.

[0156] (2) Low-temperature fixability at normal speed The low-temperature fixability at normal speed was evaluated in the same manner as in (1), except that the fixing speed was changed to 2.0 seconds per sheet in the portrait direction of A4 paper. The results are shown in Table 3.

[0157] [Table 3]

[0158] From the above results, it can be seen that, compared with Comparative Examples 1 and 2, which used a twin-screw extruder for melt-kneading, Examples 1 to 11 show a small increase in the minimum fixing temperature with increasing fixing speed, and have good low-temperature fixing properties even at high speeds. Furthermore, a comparison between Example 1 and Examples 5 to 7 shows that, as an amorphous resin, amorphous vinyl resin exhibits better low-temperature fixing properties. [Industrial Applicability]

[0159] The electrostatic image developing toner obtained by the method of the present invention is suitably used for developing latent images formed in electrostatic image developing methods, electrostatic recording methods, electrostatic printing methods and the like.

Claims

1. A method for producing a toner for developing electrostatic images, comprising the steps of melting and kneading at least a crystalline vinyl resin C, an amorphous resin A, and a release agent using an open-roll kneader, and pulverizing the kneaded product obtained in the step.

2. 2. The method for producing a toner for developing electrostatic images according to claim 1, wherein the content of the crystalline vinyl resin C is 3% by mass or more and 30% by mass or less of the total amount of the crystalline vinyl resin C and the amorphous resin A.

3. 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the crystalline vinyl resin C is an addition polymer of raw material monomers containing a (meth)acrylic acid alkyl ester having an alkyl group having from 10 to 36 carbon atoms.

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