Method for manufacturing toner for electrostatic image development

Abstract

This relates to a method for manufacturing electrostatic image developing toner with excellent heat resistance for images. [Solution] A method for producing toner for electrostatic image developing, comprising: step 1: melt-kneading at least a binder resin and a release agent, grinding the resulting pulverized material with silica, then grinding and classifying it to obtain toner powder; step 2: melt-kneading the toner powder obtained in step 1 with at least a binder resin and a release agent, then grinding it; and step 3: mixing the pulverized material obtained in step 2 with silica, then grinding and classifying it to obtain toner particles, wherein the silica content in the toner particles is 0.5% by mass or more and 15% by mass or less.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses an invention for a toner manufacturing method that allows for the production of toner with stable electrostatic properties and fluidity even after long-term use, which involves recycling the fine powder removed in the classification process.

[0003] Furthermore, Patent Document 2 discloses an invention relating to an electrophotographic toner that is excellent in both offset resistance and storage properties without impairing low-temperature fixability, obtained by a method in which a release agent is used and a pulverization step is performed in the presence of inorganic fine particles in a melt-kneading method. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2008-139611 [Patent Document 2] Japanese Patent Publication No. 2007-328043 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] While using a release agent improves resistance to hot offset printing, a problem remains if the image heat resistance is insufficient, as heat can cause the printed materials to stick together.

[0006] This invention relates to a method for manufacturing a toner for electrostatic image development that has excellent heat resistance for images. [Means for solving the problem]

[0007] The present invention relates to a method for producing electrostatic image developing toner, comprising: step 1: melt-kneading at least a binder resin and a release agent, grinding the resulting pulverized material, mixing it with silica, then grinding and classifying it to obtain toner powder; step 2: melt-kneading the toner powder obtained in step 1 with at least a binder resin and a release agent, then grinding it; and step 3: mixing the pulverized material obtained in step 2 with silica, then grinding and classifying it to obtain toner particles, wherein the silica content in the toner particles is 0.5% by mass or more and 15% by mass or less. [Effects of the Invention]

[0008] The method of the present invention provides a toner for electrostatic image development with excellent heat resistance for images. [Modes for carrying out the invention]

[0009] The present invention relates to a method for obtaining toner with a predetermined amount of silica added, by mixing a pulverized molten mixture of a binder resin and a release agent with silica, further pulverizing and classifying the resulting toner powder containing silica and a release agent, and then molten mixing the binder resin and release agent, pulverizing the mixture, mixing it with silica, and further pulverizing and classifying the mixture. The reason for the effects of the present invention is not entirely clear, but it is presumed to be as follows. Note that the following mechanism is a hypothesis and is not limited to it.

[0010] The toner is melted by the heat and pressure of the fixing roller and fixed onto the printed matter. At this time, the release agent in the toner seeps out to the interface between the fixing roller and the toner, suppressing the adhesion of the toner to the fixing roller (hot offset). At this time, a part of the release agent on the surface of the printed matter migrates to the fixing roller. If there is not enough release agent remaining on the surface of the printed matter, the deformability when heat is applied to the printed matter is insufficient, and the printed matters adhere to each other. Generally, the larger the particle size of the release agent in the toner, the easier it is to seep out to the interface between the fixing roller and the toner during toner fixing. On the other hand, if the particle size of the release agent in the toner is made too small and micro-dispersed, not enough release agent seeps out to the interface between the fixing roller and the toner, resulting in hot offset. Therefore, as a result of intensive studies by the inventors, it has been found that a toner excellent in image heat resistance of the printed matter can be obtained by giving a distribution to the particle size of the release agent in the toner, and the present invention has been completed.

[0011] After melt-kneading and pulverizing the binder resin and the release agent, the obtained pulverized product is mixed with silica, and further pulverized and classified, whereby a toner powder with silica firmly adhered to the particle surface can be obtained. At this time, due to the property that it is easy to pulverize at the interface between the binder resin and the release agent, a large amount of the release agent exists on the surface of the toner powder. Also, in the powder removed during classification, fine particles of the release agent are particularly abundant on the fine powder side (Step 1). The toner powder obtained in Step 1, in which silica is firmly adhered, is melt-kneaded and pulverized together with the binder resin and the release agent, so that the release agent component derived from the toner powder with silica adhered can maintain a fine dispersed state without merging with the newly mixed release agent component. As a result, a difference in the dispersion domain and particle size occurs between the newly mixed release agent, and the particle size of the release agent in the obtained toner can have a distribution (Step 2). Furthermore, by mixing the pulverized product having a distribution in the particle size of the release agent obtained in Step 2 with silica and further pulverizing and classifying it (Step 3), silica can be forcibly adhered to the toner particles including the release agent present on the surface of the toner particles, and excessive migration of the release agent from the toner to the roller during fixing can be suppressed. As described above, by passing through Steps 1 to 3 to give the release agent in the toner a particle size distribution and suppressing excessive transfer of the release agent from the toner to the roller during fixing, it is considered that the toner obtained by the method of the present invention is excellent in the image heat resistance of printed matter.

[0012] The method for producing the toner of the present invention includes the following Steps 1 to 3.

[0013] Step 1 is a step of obtaining toner powder by melt-kneading at least a binder resin and a release agent, pulverizing (also referred to as first coarse pulverization), mixing the pulverized product obtained with silica, and then pulverizing (also referred to as first fine pulverization) and classifying.

[0014] Examples of the binder resin include polyester resins such as amorphous polyester resins and crystalline polyester resins, vinyl resins such as styrene acrylic resins, polyamide resins, epoxy resins, polycarbonate resins, polyurethane resins, and composite resins containing two or more of these resins. In the present invention, from the viewpoint of low-temperature fixing property, a polyester resin is preferable, and it is more preferable to contain an amorphous polyester resin.

[0015] Whether the resin is crystalline or amorphous is determined by the crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the maximum peak temperature of endotherm (softening point (°C) / maximum peak temperature of endotherm (°C)) in the measurement method described in the examples below. A crystalline resin is one having a crystallinity index of 0.6 or more and 1.4 or less. An amorphous resin is one in which no endothermic peak is observed, or if observed, having a crystallinity index of less than 0.6 or more than 1.4. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and production conditions (for example, reaction temperature, reaction time, cooling rate), etc. The maximum peak temperature of endotherm refers to the temperature of the peak having the largest peak area among the observed endothermic peaks. In a crystalline resin, the maximum peak temperature of endotherm is taken as the melting point.

[0016] As the amorphous polyester resin, amorphous polyester resin or amorphous composite resin obtained by bonding a polyester resin and a styrene-based resin is preferred.

[0017] As the amorphous polyester resin, a polycondensate of an alcohol component containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component is preferred.

[0018] The alkylene oxide adduct of bisphenol A is given by formula (I):

[0019] [ka]

[0020] (In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y represent the average number of moles of alkylene oxide added, each being a positive number, and the sum of x and y is 1 or greater, preferably 1.5 or greater, and 16 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.) Compounds represented by are preferred.

[0021] From the viewpoint of low-temperature fixability, the content of the bisphenol A alkylene oxide adduct is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more, and 100 mol% or less, in the alcohol component.

[0022] Other alcohol components include aliphatic diols, diols such as bisphenol A and hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trivalent or higher alcohols such as trimethylolpropane, etc.

[0023] Examples of carboxylic acid components include aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and trivalent or higher carboxylic acid compounds.

[0024] Examples of aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0025] Examples of aliphatic dicarboxylic acid compounds include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, glutaric acid, adipic acid, sebacic acid, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0026] Examples of carboxylic acid compounds with a valency of 3 or higher include trimellitic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0027] The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monohydric carboxylic acid compound, as appropriate.

[0028] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol and carboxylic acid components.

[0029] The equivalent ratio (COOH group / OH group) of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component is preferably 0.6 or higher, more preferably 0.7 or higher, even more preferably 0.8 or higher, and preferably 1.3 or lower, more preferably 1.2 or lower, from the viewpoint of adjusting the softening point of the polyester resin.

[0030] Amorphous polyester resins can be produced, for example, by polycondensing an alcohol component and a carboxylic acid component in an inert gas atmosphere, and optionally in the presence of an esterification catalyst, co-catalyst, polymerization inhibitor, etc., at a temperature preferably 160°C or higher, more preferably 200°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

[0031] Examples of esterification catalysts include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(triethanolamine) and titanium dihydroxybis(triethanolamine). The amount of esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the total amount of alcohol and carboxylic acid components. Examples of co-catalysts for the esterification catalyst include gallic acid. The amount of co-catalyst used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, per 100 parts by mass of the total amount of alcohol and carboxylic acid components. Examples of polymerization inhibitors include tert-butylcatechol. The amount of polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, based on 100 parts by mass of the total amount of alcohol and carboxylic acid components.

[0032] In this invention, the polyester resin may be a polyester resin that has been modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins that have been grafted or blocked with phenol, urethane, epoxy, etc., by methods described in Japanese Patent Publication No. 11-133668, Japanese Patent Publication No. 10-239903, Japanese Patent Publication No. 8-20636, etc. Among modified polyester resins, urethane-modified polyester resins obtained by urethane elongation of polyester resin with a polyisocyanate compound are preferred.

[0033] The polyester resin in the composite resin is the same as the amorphous polyester resin described above, and the styrene-based resin is an addition polymer of raw material monomers containing at least styrene or a styrene derivative such as α-methylstyrene or vinyltoluene (hereinafter, styrene and styrene derivatives are collectively referred to as "styrene compounds").

[0034] The styrene compound, preferably styrene, content in the raw material monomer of the styrene 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 preservation, and 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.

[0035] Furthermore, the styrene-based resin may contain an alkyl (meth)acrylate ester with an alkyl group having 7 or more carbon atoms as a raw material monomer. Examples of alkyl (meth)acrylate esters 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. In this specification, "(iso)" means that this group may or may not be present, and when these groups are not present, it indicates that it is normal. Also, "(meth)acrylic acid" refers to acrylic acid, methacrylic acid, or both.

[0036] The number of carbon atoms in the alkyl group of (meth)acrylate is preferably 7 or more, more preferably 8 or more, and preferably 12 or less, more preferably 10 or less, from the viewpoint of improving the low-temperature fixing properties of the toner. Note that the number of carbon atoms in the alkyl ester refers to the number of carbon atoms derived from the alcohol component constituting the ester.

[0037] The content of alkyl (meth)acrylate in the raw material monomer of the styrene resin is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of low-temperature fixability, and preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of preservation.

[0038] The raw material monomers for styrene-based resins may also include raw material monomers other than styrene compounds and alkyl (meth)acrylates, such as ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenically monocarboxylic acid esters such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone.

[0039] The addition polymerization reaction of the raw material monomers for styrene-based resins can be carried out by conventional methods in the presence of polymerization initiators such as dibutyl peroxide and dicumyl peroxide, chain transfer agents, crosslinking agents, etc., in the presence of an organic solvent or without a solvent. The temperature conditions are preferably 110°C or higher, more preferably 140°C or higher, and preferably 200°C or lower, more preferably 170°C or lower.

[0040] When using an organic solvent during the addition polymerization reaction, xylene, toluene, methyl ethyl ketone, acetone, etc., can be used. The amount of organic solvent used is preferably 10 to 50 parts by mass per 100 parts by mass of the raw material monomer of the styrene resin.

[0041] The composite resin is preferably a resin in which a polyester resin and a styrene-based resin are bonded together, and more preferably a resin in which the polyester resin and the styrene-based resin are chemically bonded together via reactive monomers that can react with either the raw material monomer of the polyester resin or the raw material monomer of the styrene-based resin.

[0042] The reactive monomers are preferably compounds having at least one functional group selected from the group consisting of hydroxyl groups, carboxyl groups, epoxy groups, primary amino groups, and secondary amino groups, preferably a hydroxyl group and / or a carboxyl group, more preferably a carboxyl group, and an ethylenically unsaturated bond within the molecule. More preferably, at least one selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid, and maleic anhydride is preferred, and even more preferably, at least one selected from the group consisting of acrylic acid, methacrylic acid, and fumaric acid is preferred from the viewpoint of reactivity in polycondensation and addition polymerization reactions. However, when used together with a polymerization inhibitor, polycarboxylic acid compounds having an ethylenically unsaturated bond, such as fumaric acid, function as raw material monomers for polyester resins. In this case, fumaric acid, etc., are not the reactive monomers, but raw material monomers for polyester resins.

[0043] The amount of both reactive monomers used is preferably 1 mole or more, more preferably 2 moles or more, per 100 moles of total alcohol components of the polyester resin, from the viewpoint of improving the dispersibility of the styrene resin and polyester resin and the dispersibility of the raw materials in the toner, and preferably 30 moles or less, more preferably 20 moles or less, and even more preferably 10 moles or less, from the viewpoint of improving the low-temperature fixability of the toner.

[0044] The composite resin is preferably manufactured by the following method. When both reactive monomers are used, it is preferable to use them together with the raw material monomers of the styrene-based resin from the viewpoint of improving the dispersibility of the raw materials in the toner and the low-temperature fixing properties of the toner.

[0045] (i) A method comprising a polycondensation reaction step (A) of polyester resin using raw material monomers, followed by an addition polymerization reaction step (B) of styrene resin using raw material monomers. In this method, step (A) is carried out under reaction temperature conditions suitable for polycondensation, the reaction temperature is lowered, and step (B) is carried out under temperature conditions suitable for addition polymerization. It is preferable to add the styrene resin raw material monomer to the reaction system at a temperature suitable for addition polymerization. When both reactive monomers are used together with the styrene resin raw material monomer, both reactive monomers undergo addition polymerization and also react with the polyester resin. After step (B), the reaction temperature can be raised again, and if necessary, trivalent or higher polyester resin raw material monomers that act as crosslinking agents can be added to the polymerization system to further advance the polycondensation reaction in step (A) and the reaction with both reactive monomers.

[0046] (ii) A method in which a polycondensation reaction (A) is carried out using polyester resin raw material monomers after an addition polymerization reaction (B) using styrene resin raw material monomers. In this method, step (B) is carried out under reaction temperature conditions suitable for the addition polymerization reaction, and then the reaction temperature is increased to carry out the polycondensation reaction in step (A) under temperature conditions suitable for the polycondensation reaction. When both reactive monomers are used together with the raw material monomers of the styrene resin, both reactive monomers participate in both the addition polymerization reaction and the polycondensation reaction. The raw material monomers for the polyester resin may be present in the reaction system during the addition polymerization reaction, or they 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.

[0047] (iii) A method in which the polycondensation reaction of polyester resin using raw material monomers (A) and the addition polymerization reaction of styrene resin using raw material monomers (B) proceed in parallel under conditions. In this method, steps (A) and (B) are carried out in parallel under reaction temperature conditions suitable for addition polymerization, the reaction temperature is increased, and under temperature conditions suitable for polycondensation, a raw material monomer of a trivalent or higher polyester resin that acts as a crosslinking agent is added to the polymerization system as needed, and the polycondensation reaction of step (A) is carried out further. At that time, under temperature conditions suitable for polycondensation, a polymerization inhibitor can be added to allow only the polycondensation reaction to proceed. When both reactive monomers are used, both reactive monomers participate in both the addition polymerization reaction and the polycondensation reaction.

[0048] In method (i) above, a pre-polymerized polyester resin may be used instead of step (A) in which the polycondensation reaction is carried out. In method (iii) above, when the reaction is carried out under conditions in which steps (A) and (B) proceed in parallel, a mixture containing the raw material monomer of a styrene-based resin can be added dropwise to a mixture containing the raw material monomer of a polyester resin and the reaction can be carried out.

[0049] Methods (i) to (iii) described above are preferably carried out in the same container.

[0050] In the composite resin, the mass ratio of polyester resin to styrene resin (polyester resin / styrene resin) is preferably 60 / 40 or higher, more preferably 70 / 30 or higher, and even more preferably 75 / 25 or higher, from the viewpoint of low-temperature fixability, and from the viewpoint of improving the dispersibility of raw materials in toner, it is preferably 98 / 2 or lower, more preferably 95 / 5 or lower, and even more preferably 90 / 10 or lower. In the above calculation, the mass of polyester resin is the amount obtained by subtracting the amount of reaction water (calculated value) dehydrated by the polycondensation reaction from the mass of the raw material monomers of the polyester resin used, and the amounts of both reactive monomers are included in the amount of raw material monomers of the polyester resin. The amount of styrene resin is the total amount of raw material monomers of the styrene resin.

[0051] The softening point of amorphous polyester resin is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, from the viewpoint of electrostatic stability, and 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.

[0052] Furthermore, the amorphous polyester resin may be composed of resins with different softening points, from the viewpoint of low-temperature fixability and fixation width. The difference in softening points between the two resins is preferably 10°C or more, more preferably 20°C or more, and preferably 60°C or less, more preferably 45°C or less.

[0053] The softening point of the amorphous polyester resin (resin AH) with a high softening point is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and even more preferably 125°C or higher, from the viewpoint of fixing width, and preferably 170°C or lower, more preferably 160°C or lower, from the viewpoint of low-temperature fixing properties.

[0054] Furthermore, the softening point of the amorphous polyester resin (resin AL) with a lower softening point is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, from the viewpoint of electrostatic stability, and 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 fixation.

[0055] 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 preferably 90 / 10 or less, more preferably 80 / 20 or less, and even more preferably 70 / 30 or less.

[0056] The glass transition temperature of amorphous polyester resins is preferably 40°C or higher, more preferably 50°C or higher, from the viewpoint of storage properties, and preferably 80°C or lower, more preferably 70°C or lower, from the viewpoint of low-temperature fixation properties.

[0057] The acid value of the amorphous polyester resin is preferably 1 mg KOH / g or more, more preferably 3 mg KOH / g or more, from the viewpoint of low-temperature fixability, and preferably 40 mg KOH / g or less, more preferably 35 mg KOH / g or less, from the viewpoint of electrostatic stability.

[0058] The content of amorphous polyester resin 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, and 100% by mass or less.

[0059] The content of the binder resin in the toner powder is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 98.5% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0060] Examples of release agents include hydrocarbon waxes, ester waxes, silicone waxes, and fatty acid amide waxes.

[0061] Examples of hydrocarbon waxes include mineral or petroleum-based hydrocarbon waxes such as paraffin wax and Fischer-Tropsch wax; and synthetic hydrocarbon waxes such as polyethylene wax, polypropylene wax, ethylene-propylene copolymer wax, and polyolefin wax such as polybutene wax. Examples of ester waxes include mineral or petroleum-based ester waxes such as montan wax; plant-based ester waxes such as carnauba wax, rice wax, and candelilla wax; animal-based ester waxes such as beeswax; and synthetic ester waxes obtained by condensing carboxylic acids such as fatty acids with alcohols such as aliphatic alcohols. Examples of fatty acid amide waxes include oleic acid amide and stearic acid amide. Among these, hydrocarbon waxes and / or synthetic ester waxes are preferred from the viewpoint of low-temperature fixability and image heat resistance.

[0062] Suitable synthetic ester waxes include pentaerythritol-based ester waxes, dipentaerythritol-based ester waxes, and aliphatic monoalcohol-based ester waxes.

[0063] Preferably, the pentaerythritol-based ester wax is an ester of pentaerythritol and an aliphatic monocarboxylic acid, the dipentaerythritol-based ester wax is an ester of dipentaerythritol and an aliphatic monocarboxylic acid, and the aliphatic monoalcohol-based ester wax is an ester of an aliphatic monoalcohol and an aliphatic monocarboxylic acid.

[0064] Examples of aliphatic monocarboxylic acids include stearic acid, behenic acid, caprylic acid, lauric acid, myristic acid, isostearic acid, palmitic acid, oleic acid, condensed ricinoleic acid, and 12-hydroxystearic acid.

[0065] The number of carbon atoms in the aliphatic monocarboxylic acid is preferably 10 or more, more preferably 12 or more, even more preferably 14 or more, and preferably 30 or less, more preferably 28 or less, and even more preferably 26 or less.

[0066] Examples of aliphatic monoalcohols include behenyl alcohol, stearyl alcohol, caprylic alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, oleyl alcohol, aragisyl alcohol, and ceryl alcohol.

[0067] The number of carbon atoms in the aliphatic monoalcohol is preferably 10 or more, more preferably 12 or more, even more preferably 14 or more, and preferably 30 or less, more preferably 28 or less, and even more preferably 26 or less.

[0068] Specific examples of pentaerythritol-based ester waxes include pentaerythritol tetrabehenate, pentaerythritol tetrastearate, and pentaerythritol tetrapalmitate.

[0069] Specific examples of dipentaerythritol-based ester waxes include dipentaerythritol hexastearate, dipentaerythritol hexabenate, and dipentaerythritol stearate.

[0070] Specific examples of aliphatic monoalcohol ester waxes include behenyl behenate, behenyl stearate, stearyl stearate, and stearyl behenate.

[0071] The melting point of the release agent is preferably 60°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher, from the viewpoint of toner release properties, and preferably 110°C or lower, more preferably 100°C or lower, from the viewpoint of improving the low-temperature fixability of the toner.

[0072] The amount of release agent used in step 1 is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 9 parts by mass or less, and even more preferably 8 parts by mass or less, based on 100 parts by mass of the binder resin used in step 1.

[0073] In step 1, raw materials that can be melt-kneaded together with the binder resin (binder) and release agent include additives such as colorants, charge control agents, magnetic powders, fluidity improvers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, and cleaning properties improvers.

[0074] As colorants, dyes, pigments, magnetic materials, etc., used as colorants for toners can be used. Examples include carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, etc. In this invention, the toner may be either black toner or color toner.

[0075] The amount of colorant used in step 1 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, based on 100 parts by mass of the binder resin used in step 1, from the viewpoint of improving the image density and low-temperature fixability of the toner.

[0076] The charge control agent is not particularly limited and may contain either a positively charged charge control agent or a negatively charged charge control agent.

[0077] Positively charged charge control agents include nigrosine dyes, such as "Nigrosine Base EX," "Oil Black BS," "Oil Black SO," "Bontron N-01," "Bontron N-04," "Bontron N-07," "Bontron N-09," "Bontron N-11," and "Bontron N-79" (all manufactured by Orient Chemical Industries, Ltd.); triphenylmethane-based dyes containing tertiary amines as side chains; quaternary ammonium salt compounds, such as "Bontron P-51" (manufactured by Orient Chemical Industries, Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX." Examples include VP435 (manufactured by Clariant), polyamine resins such as AFP-B (manufactured by Orient Chemical Industries, Ltd.), imidazole derivatives such as PLZ-2001 and PLZ-8001 (both manufactured by Shikoku Chemicals, Ltd.), and styrene-acrylic resins such as FCA-701PT and FCA-201-PS (manufactured by Fujikura Chemicals, Ltd.).

[0078] Furthermore, as negative charge control agents, metal-containing azo dyes, such as "Barifast Black 3804," "Bontron S-31," "Bontron S-32," "Bontron S-34," and "Bontron S-36" (all manufactured by Orient Chemical Industries, Ltd.), "Eisenspiron Black TRH," and "T-77" (manufactured by Hodogaya Chemical Co., Ltd.); metal compounds of benzyl acid compounds, such as "LR-147" and "LR-297" (both manufactured by Nippon Carlit Co., Ltd.); metal compounds of salicylic acid compounds, such as "Bontron E-81," "Bontron E-84," "Bontron E-88," and "Bontron E-304" (all manufactured by Orient Chemical Industries, Ltd.), and "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.); copper phthalocyanine dyes; and quaternary ammonium salts, such as "COPY CHARGE NX" Examples include VP434 (manufactured by Clariant), nitroimidazole derivatives, organometallic compounds, etc.

[0079] From the viewpoint of the charge stability of the toner, the amount of charge control agent used in step 1 is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of the binder resin used in step 1.

[0080] The binder resin, release agent, and, if necessary, internal additives such as colorants and charge control agents may be mixed all at once or in separate batches. However, it is preferable to mix them beforehand using a mixer such as a Henschel mixer or ball mill before supplying them to the melt-mixing process.

[0081] For melt kneading, known kneaders such as closed-type kneaders, single-screw or twin-screw extruders, and open-roll type kneaders can be used, but in the present invention, it is preferable to use an open-roll type kneader that can physically provide a high kneading share.

[0082] An open-roll type kneader is one in which the kneading section is not sealed but open, allowing for easy dissipation of the heat generated during melt-mixing. The two-roll open-roll type kneader used in this invention is equipped with two rolls and has a raw material supply port and a kneaded material discharge port located along the axial direction of the rolls. From the viewpoint of production efficiency, a continuous two-roll open-roll type kneader is preferable.

[0083] The two-roll open-type kneader used in the present invention is preferably a kneader equipped with two rolls with different peripheral speeds, namely a roll with a high peripheral speed (high-speed roll) and a roll with a low peripheral speed (low-speed roll). In the present invention, from the viewpoint of dispersibility of the kneaded material, it is preferable that the high-speed roll functions as a heating roll and the low-speed roll functions as a cooling roll, namely that the set temperature of the high-speed roll is higher than the set temperature of the low-speed roll. If the set temperatures of the rolls differ on the raw material input side and the kneaded material discharge side, it is preferable that the set temperature of the high-speed roll is higher than the set temperature of the low-speed roll at least on the raw material input side, and it is more preferable that the set temperature of the high-speed roll is higher than the set temperature of the low-speed roll on both the raw material input side and the kneaded material discharge side.

[0084] The temperature of the roll can be adjusted, for example, by the temperature of the heat transfer medium passed through the roll. Each roll may also have its interior divided into two or more sections through which heat transfer mediums with different temperatures are passed.

[0085] From the viewpoint of reducing mechanical force during melting and kneading and suppressing heat generation, the temperature on the raw material input side of the high-speed roll is preferably 80°C or higher, more preferably 100°C or higher, even more preferably 120°C or higher, and preferably 160°C or lower, more preferably 150°C or lower. From a similar viewpoint, the temperature on the raw material input side of the low-speed 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.

[0086] In both high-speed and low-speed rolls, it is preferable that the temperature on the raw material input side is higher than the temperature on the mixed material discharge side. The temperature difference between the raw material input side and the mixed material discharge side is preferably 20°C or higher, more preferably 30°C or higher, and preferably 60°C or lower, more preferably 50°C or lower, from the viewpoint of preventing the mixed material from detaching from the rolls and reducing mechanical force during melt kneading to suppress heat generation.

[0087] The temperature on the raw material input side of the high-speed and low-speed rolls refers to the set temperature at the raw material input end, while the temperature on the kneaded material discharge side refers to the set temperature at the kneaded material discharge end.

[0088] The peripheral speed of the high-speed roll is preferably 2 m / min or more, more preferably 10 m / min or more, even more preferably 25 m / min or more, and preferably 100 m / min or less, more preferably 75 m / min or less, and even more preferably 50 m / min or less, from the viewpoint of reducing mechanical force during mixing and suppressing heat generation. The peripheral speed of the low-speed roll is preferably 1 m / min or more, more preferably 5 m / min or more, even more preferably 15 m / min or more, and preferably 90 m / min or less, more preferably 60 m / min or less, and even more preferably 30 m / min or less, from the same viewpoint. Furthermore, the ratio of the peripheral speeds of the two rolls (low-speed roll / high-speed roll) is preferably 1 / 10 or more, more preferably 3 / 10 or more, and preferably 9.9 / 10 or less, and even more preferably 8 / 10 or less.

[0089] Furthermore, there are no particular limitations on the structure, size, or material of each roll. The surface of the roll has grooves used for mixing, and these grooves can be straight, spiral, wavy, or uneven.

[0090] After melt-mixing, the resulting mixture is cooled appropriately until it reaches a hardness suitable for pulverization, and then pulverized (first coarse pulverization). Here, cooling refers to cooling the mixture to 0°C to 50°C, or to below the glass transition temperature of the binder resin in the mixture.

[0091] Examples of grinders used for the initial coarse grinding include hammer mills, cutter mills, atomizers, and Rotoplexes.

[0092] In the first coarse grinding stage, it is preferable to coarsely grind the kneaded material to a particle size of approximately 0.1 to 3 mm, then pass it through a sieve with a mesh opening of approximately 2 to 3 mm, and mix the pulverized material that has passed through the sieve with silica, with a maximum diameter of 2 to 3 mm or less. Hereinafter, the pulverized material obtained by the first coarse grinding stage will also be referred to as the first coarse pulverized material.

[0093] From the viewpoint of dispersibility in toner particles, it is preferable that the silica be hydrophobic silica that has undergone hydrophobic treatment.

[0094] Examples of hydrophobic agents used to hydrophobize the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0095] The BET specific surface area of ​​silica is preferably 10 m² from the viewpoint of durability. 2 / g or more, comfortably within 30m 2 / g or more, more preferably 80mg 2 It is 1 / g or more, and from the viewpoint of dispersibility in toner particles, preferably 350m 2 / g or less, more preferably 320m 2 / g or less, more preferably 250m 2 It is less than / g.

[0096] The number-average particle diameter of silica is preferably 5 nm or larger, more preferably 10 nm or larger, even more preferably 15 nm or larger, and preferably 250 nm or smaller, more preferably 200 nm or smaller, even more preferably 100 nm or smaller, even more preferably 50 nm or smaller, and even more preferably 30 nm or smaller, from the viewpoint of dispersibility in toner particles.

[0097] The amount of silica used in Step 1 is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, still more preferably 2 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the first coarse pulverized product.

[0098] Examples of the pulverizer used for the first fine pulverization include jet mills such as fluidized bed jet mills and impact plate jet mills, and mechanical mills.

[0099] Examples of the classifier used for classification include air classifiers, inertial classifiers, and sieve classifiers. During the classification step, the pulverized products (coarse powder and fine powder) that were not sufficiently pulverized and removed may be returned to the pulverization step, and the fine pulverization step and the classification step may be repeated as necessary.

[0100] In the present invention, the toner powder obtained in Step 1 may be the classified powder obtained in the classification step of Step 1 or the powder removed during classification. The powder removed during classification includes the powder (coarse powder) removed by upper limit classification and the powder (fine powder) removed by lower limit classification. From the viewpoint of production efficiency, in the present invention, it is preferable to use the fine powder as the toner powder in Step 2.

[0101] The volume median diameter (D 50Y ) of the toner powder is preferably 1.0 μm or more, more preferably 2.0 μm or more, and preferably 6.0 μm or less, more preferably 5.0 μm or less. In this specification, the volume median diameter (D 50 ) means the particle diameter at which the cumulative volume frequency calculated by volume fraction becomes 50% when calculated from the smaller particle diameter.

[0102] The difference (D 50X ) between the volume median diameter (D 50Y ) of the toner particles and the volume median diameter (D 50X -D 50YThe particle size is preferably 1.0 μm or larger, more preferably 1.2 μm or larger, even more preferably 1.4 μm or larger, and preferably 10 μm or smaller, more preferably 6 μm or smaller, and even more preferably 4 μm or smaller.

[0103] The silica content in the toner powder is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, and preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 8% by mass or less.

[0104] Step 2 is a process of melt-kneading the toner powder obtained in Step 1 with at least a binder resin and a release agent, and then grinding (also called second coarse grinding).

[0105] The binder resin and release agent used in step 2 are the same as those used in step 1, and it is preferable that they are the same substance.

[0106] The amount of toner powder used in step 2 is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of the binder resin used in step 2.

[0107] The amount of release agent used in step 2 is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 9 parts by mass or less, and even more preferably 8 parts by mass or less, based on 100 parts by mass of the binder resin used in step 2.

[0108] In step 2, the raw materials that can be melt-kneaded together with the toner powder, binder resin (binder), and release agent include, as in step 1, additives such as colorants, charge control agents, magnetic powders, fluidity improvers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, and cleaning properties improvers.

[0109] The amount of colorant used in step 2 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, based on 100 parts by mass of the binder resin used in step 2, from the viewpoint of improving the image density and low-temperature fixability of the toner.

[0110] The amount of charge control agent used in step 2 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, based on 100 parts by mass of the binder resin used in step 2, from the viewpoint of the charge stability of the toner.

[0111] The mixture containing toner powder, binder resin, and release agent, and optionally internal additives such as colorants and charge control agents, may be mixed all at once or in portions, but it is preferable to mix them beforehand in a mixer such as a Henschel mixer or ball mill before supplying them to the melt-mixing process.

[0112] Melt mixing can be carried out in the same manner as in step 1.

[0113] After melt-mixing, the resulting mixture is cooled appropriately until it reaches a hardness suitable for pulverization, and then pulverized (second coarse pulverization). Here, cooling refers to cooling the mixture to 0°C to 50°C, or to below the glass transition temperature of the binder resin in the mixture.

[0114] For the second coarse grinding stage, the same grinder as for the first coarse grinding stage can be used.

[0115] In the second coarse grinding stage, the kneaded material is coarsely ground to a particle size of approximately 0.1 to 3 mm, and then passed through a sieve with a mesh opening of approximately 2 to 3 mm. The pulverized material that passes through the sieve is preferably a pulverized material with a maximum diameter of 2 to 3 mm or less. Hereinafter, the pulverized material obtained by the second coarse grinding stage will also be referred to as the second coarse pulverized material.

[0116] Step 3 is a process in which the pulverized material obtained in Step 2 (second coarse pulverized material) is mixed with silica, then pulverized (second fine pulverization) and classified to obtain toner particles.

[0117] The silica used in step 3 is the same as the silica used in step 1, and the grinding (second fine grinding) and classification are the same as the first fine grinding and classification in step 1.

[0118] The degree of the second fine grinding is preferably adjusted as appropriate according to the desired particle size of the toner particles.

[0119] The silica content in the toner particles is 0.5% by mass or more, preferably 1% by mass or more, and more preferably 2% by mass or more, from the viewpoint of image heat resistance, and 15% by mass or less, preferably 12% by mass or less, and more preferably 8% by mass or less, from the viewpoint of low-temperature fixation.

[0120] Furthermore, the toner powder content in the toner particles is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 9% by mass or more, from the viewpoint of image heat resistance, and preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of kneading stability.

[0121] The content of the binder resin in the toner particles is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, and preferably 98% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.

[0122] Volume-intermediate particle size of toner particles (D 50X The particle size is preferably 3.0 μm or larger, more preferably 4.0 μm or larger, and preferably 15.0 μm or smaller, more preferably 10.0 μm or smaller.

[0123] The toner particles obtained in step 3 can be used as toner as is, but in the present invention, it is preferable to further perform step 4, in which the toner particles obtained in step 3 are mixed with an external additive, from the viewpoint of improving transferability.

[0124] Examples of external additives include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles. Two or more types may be used in combination. Among these, silica is preferred, and from the viewpoint of toner transferability, hydrophobic silica that has been hydrophobicized is more preferred.

[0125] Examples of hydrophobic agents used to hydrophobize the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0126] The number-average particle size of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 90 nm or less, from the viewpoint of the toner's chargeability, fluidity, and transferability.

[0127] The mixing of toner particles and external additives can be carried out according to conventional methods, and a mixer such as a Henschel mixer can be used.

[0128] From the viewpoint of the toner's electrostatic properties, fluidity, and transferability, the amount of external additive used is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, and preferably 5 parts by mass or less, and more preferably 3 parts by mass or less, per 100 parts by mass of toner particles.

[0129] The electrostatic image developing toner obtained by the method of the present invention can be used as is as a one-component developing toner, or as a two-component developing toner used in combination with a carrier, in image forming apparatuses using either a one-component developing method or a two-component developing method, respectively. [Examples]

[0130] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way by these examples. The physical properties of the resin and the like were measured by the following methods.

[0131] [Softening point of resin] Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), 1 g of sample is heated at a heating rate of 6°C / min while a load of 1.96 MPa is applied by a plunger, and the sample is extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester is plotted against temperature, and the temperature at which half of the sample has flowed out is defined as the softening point.

[0132] [Maximum peak temperature of endothermic resin] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample is weighed into an aluminum pan and cooled from room temperature (25°C) to 0°C at a rate of 10°C / min, and maintained at 0°C for 1 minute. Then, the temperature is increased to 200°C at a rate of 10°C / min and measurements are taken. Among the observed endothermic peaks, the temperature of the peak with the largest peak area is defined as the maximum endothermic peak temperature.

[0133] [Glass transition temperature of resins] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled to 0°C at a rate of 10°C / min. Next, the sample is heated to 200°C at a rate of 10°C / min, and the endothermic peak is measured. The temperature at the intersection of the extension of the baseline below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the peak apex is defined as the glass transition temperature.

[0134] [Acid value of resins] Measurements will be performed according to the method of JIS K 0070:1992. However, the measurement solvent will be changed from the ethanol and ether mixed solvent specified in JIS K 0070 to an acetone and toluene mixed solvent (acetone:toluene = 1:1 (volume ratio)) for amorphous resins.

[0135] [Melting point of release agent] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a rate of 10°C / min. Next, the sample is heated to 200°C at a rate of 10°C / min, the heat quantity is measured, and the maximum endothermic peak temperature is defined as the melting point.

[0136] [BET specific surface area of ​​silica] The measurement will be performed by nitrogen adsorption under the following conditions. • Measuring device: Specific surface area measuring device "Micromeritics FlowSorbIII" (manufactured by Shimadzu Corporation) Sample size: 0.04-0.08g Degassing conditions: 40°C, 10 minutes • Adsorbent gas: Nitrogen gas

[0137] [Number average particle size of silica and external additives] The particle size (average of major and minor axes) of 500 particles (primary particles) is measured from scanning electron microscope (SEM) images, and the numerical average of these values ​​is used.

[0138] [Volume-intermediate particle size (D) of toner powder and toner particles] 50 )〕 • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Dispersion: Prepared by dissolving polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] in the electrolyte to adjust the concentration to 5% by mass. • Dispersion conditions: Add 10 mg of the sample to 5 mL of the dispersion and disperse for 1 minute using an ultrasonic disperser (machine name: US-1 manufactured by SND Corporation, output: 80W). Then, add 25 mL of electrolyte and disperse for another minute using the ultrasonic disperser to prepare the sample dispersion. • Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles can be measured in 20 seconds. Then, the 30,000 particles are measured, and the volume median particle size (D) is determined from the particle size distribution. 50 )

[0139] Resin manufacturing example 1 The raw material monomers for polyester resins other than trimellitic anhydride and fumaric acid, esterification catalysts, and co-catalysts shown in Table 1 were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube and dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 180°C, and trimellitic anhydride, fumaric acid, and polymerization inhibitors shown in Table 1 were added. The mixture was held at 180°C for 1 hour, then heated 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 carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, yielding amorphous polyester resin (resin AH1). The physical properties are shown in Table 1.

[0140] Resin manufacturing example 2 The raw material monomers for polyester resins other than trimellitic anhydride, esterification catalysts, and co-catalysts shown in Table 1 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a drop-flow condenser with a dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 210°C, trimellitic anhydride shown in Table 1 was added, and the mixture was reacted at 210°C for 1 hour. The reaction was then carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, yielding amorphous polyester resin (resin AH2). The physical properties are shown in Table 1.

[0141] Resin manufacturing example 3 The raw material monomers for polyester resins other than trimellitic anhydride and fumaric acid, esterification catalysts, and co-catalysts shown in Table 1 were placed in a 10-liter four-necked flask equipped with a drop-through condenser with a nitrogen inlet tube and dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 160°C, and a mixture of both reactive monomers shown in Table 1, the raw material monomers for styrene-based resins, and a polymerization initiator was added dropwise over 1 hour using a dropping funnel. After addition, the addition polymerization reaction was allowed to mature at 160°C for 1 hour, then the temperature was raised to 200°C and the pressure was reduced to 10 kPa for 1 hour. After opening the pressure, 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 held at 180°C for 1 hour, then the temperature was raised from 180°C to 210°C at a rate of 10°C / h, and the reaction was carried out at 210°C for 1 hour. Furthermore, the reaction was carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, yielding an amorphous composite resin (resin AH3). The physical properties are shown in Table 1.

[0142] [Table 1]

[0143] Resin manufacturing example 4 The raw material monomers for polyester resins other than fumaric acid, the esterification catalyst, and the co-catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube and a dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 180°C, and the fumaric acid and polymerization inhibitor shown in Table 2 were added. The mixture was held at 180°C for 1 hour, then heated 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 carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, yielding amorphous polyester resin (resin AL1). The physical properties are shown in Table 2.

[0144] Resin manufacturing example 5 The raw material monomers, esterification catalyst, and co-catalyst for the polyester resin shown in Table 2 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a fall-flow condenser, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 210°C and the reaction was carried out under reduced pressure of 10 kPa until the softening point shown in Table 2 was reached to obtain amorphous polyester resin (resin AL2). The physical properties are shown in Table 2.

[0145] Resin manufacturing example 6 The raw material monomers for polyester resins other than fumaric acid, esterification catalysts, and co-catalysts shown in Table 2 were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 160°C, and a mixture of both reactive monomers shown in Table 2, the raw material monomers for styrene-based resins, and a polymerization initiator was added dropwise over 1 hour using a dropping funnel. After addition, the addition polymerization reaction was allowed to mature at 160°C for 1 hour, then the temperature was raised to 200°C and the pressure was reduced to 10 kPa for 1 hour. After opening the pressure, the temperature was lowered to 180°C, and the fumaric acid and polymerization inhibitor shown in Table 2 were added. The mixture was held at 180°C for 1 hour, then the temperature was raised from 180°C to 210°C at a rate of 10°C / h, and the reaction was carried out at 210°C for 1 hour. Furthermore, the reaction was carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, yielding an amorphous composite resin (resin AL3). The physical properties are shown in Table 2.

[0146] [Table 2]

[0147] Example 1 [Process 1] 50 parts by mass of resin AH1, 50 parts by mass of resin AL1, 5 parts by mass of coloring agent "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (CI pigment blue 15:3)), 4 parts by mass of release agent "FNP-0090" (manufactured by Nippon Seiro Co., Ltd., Fischer-Tropsch wax, melting point: 90℃), and 0.5 parts by mass of charge control agent "Bontron E-304" (manufactured by Orient Chemical Industry Co., Ltd.) were thoroughly mixed in a Henschel mixer, and then melt-kneaded using a continuous two-roll open-roll kneader "Nidex" (manufactured by Nippon Coke Industries Co., Ltd., roll outer diameter: 14 cm, effective roll length: 80 cm) under the conditions shown below.

[0148] The operating conditions for the continuous two-roll open-type kneader were: high-speed roll (front roll) peripheral speed of 32.4 m / min, low-speed roll (back roll) peripheral speed of 21.7 m / min, and roll gap of 0.1 mm. The heating and cooling medium temperatures within the rolls were 145°C on the raw material input side and 100°C on the kneaded material discharge side of the high-speed roll, and 65°C on the raw material input side and 35°C on the kneaded material discharge side of the low-speed roll. The raw material mixture supply rate was 10 kg / h, and the average residence time was approximately 3 minutes.

[0149] The resulting mixture was cooled and coarsely ground using a Rotoplex pulverizer (manufactured by Hosokawa Micron Corporation), and a coarse pulverized material with a volume median particle size of 2 mm or less was obtained using a sieve with a mesh size of 2 mm. To the obtained coarse pulverized material, silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobic treatment agent: DMDS, number average particle size: 16 nm, BET specific surface area: 130 m²) was added. 2 Mix 1.1 parts by mass (the amount of silica so that the silica content in the mixture is 1% by mass) and use an impact plate type jet mill "IDS-2" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) and an airflow classifier "DS-2" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to determine the medium particle size by volume (D 50 The material was finely ground and classified so that the particle size (D) was 6.0 μm. At this time, the fine powder obtained by classification was collected and used as toner powder 1 containing silica and a release agent. The volume median particle size (D) of the toner powder was determined. 50Y The diameter was 4.1 μm.

[0150] [Process 2] 50 parts by mass of resin AH1, 50 parts by mass of resin AL1, 5 parts by mass of coloring agent "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (CI pigment blue 15:3)), 4 parts by mass of release agent "FNP-0090" (manufactured by Nippon Seiro Co., Ltd., Fischer-Tropsch wax, melting point: 90℃), 0.5 parts by mass of charge control agent "Bontron E-304" (manufactured by Orient Chemical Industry Co., Ltd.), and 15 parts by mass of toner powder 1 were thoroughly mixed in a Henschel mixer, and then melt-kneaded using a continuous two-roll open-roll kneader "Nidex" (manufactured by Nippon Coke Industries Co., Ltd., roll outer diameter: 14 cm, effective roll length: 80 cm) under the conditions shown below.

[0151] The operating conditions for the continuous two-roll open-type kneader were a peripheral speed of 32.4 m / min for the high-speed roll (front roll), a peripheral speed of 21.7 m / min for the low-speed roll (back roll), and a roll gap of 0.1 mm. The heating and cooling medium temperatures within the rolls were 145°C on the raw material input side and 100°C on the kneaded material discharge side of the high-speed roll, and 65°C on the raw material input side and 35°C on the kneaded material discharge side of the low-speed roll. The raw material mixture supply rate was 10 kg / hr, and the average residence time was approximately 3 minutes.

[0152] The resulting mixture was cooled and coarsely ground using a Rotoplex pulverizer (manufactured by Hosokawa Micron Corporation). A sieve with a mesh size of 2 mm was used to obtain a coarsely ground product with a median particle size of 2 mm or less.

[0153] [Step 3] To the obtained coarsely ground material, silica "R972" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, number average particle size: 16 nm, BET specific surface area: 130 m²) was added. 2 Mix 1.1 parts by mass (the amount of silica so that the silica content in the toner particles is 1% by mass) and use an impact plate type jet mill "IDS-2" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) and an airflow classifier "DS-2" (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to determine the medium volume particle size (D 50 The particles were finely ground and classified to obtain toner particles with a size of 6.0 μm.

[0154] [Step 4] To 100 parts by mass of the obtained toner particles, hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, number average particle size: 16 nm, BET specific surface area: 130 m²) was added as an external additive. 2 1.0 part by mass of (1 / g) and 1.0 part by mass of "RX50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: HMDS, number average particle size: 40 nm) were added, and the mixture was mixed using a Henschel mixer at 3700 r / min for 3 minutes to obtain toner.

[0155] Examples 2-15, Comparative Examples 1-4 In step 1, toner powders (toner powders 2-15, 18-21) were obtained in the same manner as in Example 1, except that the binder resin, colorant, release agent, and silica listed in Table 3 were used. Using the obtained toner powder, step 2 was carried out using the binder resin, colorant, and release agent listed in Table 4, and step 3 was carried out by mixing the silica listed in Table 5 with the coarsely ground material. The procedure was carried out up to step 4 in the same manner as in Example 1 to obtain toner.

[0156] Example 16 Toner was obtained in the same manner as in Example 3, except that a twin-screw extruder was used instead of a continuous twin-roll open-roll kneader in steps 1 and 2 of the melt-kneading process. The operating conditions for the twin-screw extruder were a barrel setting temperature of 100°C, a shaft rotation speed of 200 r / min (circumferential speed of shaft rotation of 0.30 m / sec), and a mixture supply rate of 10 kg / h.

[0157] Example 17 In step 1 of Example 1, the volume median particle size (D 50 The toner was obtained in the same manner as in Example 1, except that the material was finely ground and classified so that the particle size was 4.2 μm to obtain toner powder (toner powder 17), and the obtained toner powder was used in step 2.

[0158] Comparative Example 5 Toner was obtained in the same manner as in Example 3, except that step 1 was omitted and toner powder 3 was not used in step 2.

[0159] Comparative Example 6 Toner was obtained in the same manner as in Example 3, except that 0.66 parts by mass of hydrophobic silica "R972" was used instead of toner powder 3, and the amount of silica used to be mixed with the coarse pulverized material in step 3 was changed to 5.1 parts by mass (an amount such that the silica content in the toner particles is 5% by mass).

[0160] Details of the colorants, release agents, and silica used in the examples and comparative examples are as follows.

[0161] [Coloring agents] • PB15:3: "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (CI pigment blue 15:3)) • CB: "Mogul-L" (Manufactured by Cabot, Carbon Black) • PR122: "FASTOGEN SUPER MAGENTA R3-E" (manufactured by DIC Corporation, quinacridone-based pigment (CI Pigment Red 122)) • PY185: "Pariotol Yellow D1155" (manufactured by Sun Chemical, isoindoline pigment (CI Pigment Yellow 185))

[0162] [Release agent] • FNP-0090: "FNP-0090" (manufactured by Nippon Seiro Co., Ltd., Fischer-Tropsch wax, melting point: 90℃) • WEP-8: "WEP-8" (manufactured by NOF Corporation, pentaerythritol tetrabehenate (synthetic ester wax), melting point: 80℃) • Carnauba: "Carnauba Wax C1" (manufactured by Kato Yoko Co., Ltd., melting point: 83℃)

[0163] 〔silica〕 • R972: "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobic treatment agent: DMDS, number average particle size: 16 nm, BET specific surface area: 130 m²) 2 / g) • R976: "R976" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, number average particle size: 8nm, hydrophobic treatment agent: DMDS, BET specific surface area: 300m²) 2 / g) • RX50: "RX50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobic treatment agent: HMDS, number average particle size: 40 nm, BET specific surface area: 50 m²) 2 / g)

[0164] Test example (1) Heat resistance of images in single color A modified version of the non-magnetic single-component developer "COREFIDO C844dnw" (manufactured by OKI Electric Industry Co., Ltd.) was used to enable fixing outside the device. Toner was then mounted on this modified device, and a printout was obtained in an unfixed state (print area: 2cm x 12cm, toner amount: 0.8mg / cm²). 2 Subsequently, a fuser (fixing speed 300 mm / sec) adjusted to achieve a total fixing pressure of 40 kgf was used, and the temperature of the fuser roll was set to 170°C to fix the unfixed printed material. The paper used for printing was "CopyBond SF-70NA" (manufactured by Sharp Corporation, 75 g / m²). 2 ) was used. The fixed images are superimposed, at 100g / cm². 2 Under the specified load, temperature of 50°C, and relative humidity of 50%, the printed material was left for two days. After two days, the condition of the printed material was visually observed when it was peeled off, and the image heat resistance was evaluated according to the following evaluation criteria. [Evaluation Criteria] A: No detachment of the fixed image (document offset) can be confirmed. B: No peeling of the fixed image was observed, but slight sticking occurred when peeling it off. C: When peeling, some adhesion occurs, and slight peeling (such as white spots) can be seen in the fixed image. D: When peeling it off, it sticks, and a clear white gap can be seen on the fixed image side. E: The papers are stuck together and will be damaged if you try to separate them.

[0165] (2) Image heat resistance in secondary and tertiary colors The image heat resistance in secondary and tertiary colors was evaluated using toner sets combining the toners of the examples and comparative examples shown in Table 6. A toner set was mounted on a modified non-magnetic single-component developer unit, "COREFIDO C844dnw" (manufactured by OKI Electric Industry Co., Ltd.), which was modified to allow fixing outside the unit. Prints were obtained in the unfixed state (print area: 2cm x 12cm, red (yellow toner and magenta toner both had a toner load of 0.4mg / cm²)). 2 ), Green (Yellow toner and cyan toner both have a toner load of 0.4 mg / cm²) 2 ), Blue (both cyan and magenta toners have a toner load of 0.4 mg / cm²) 2 ), and brown (yellow toner, magenta toner, and black toner all have a toner load of 0.3 mg / cm²). 2 Subsequently, a fuser (fixing speed 300 mm / sec) adjusted to achieve a total fixing pressure of 40 kgf was used, and the temperature of the fuser roll was set to 170°C to fix the unfixed printed material. The paper used for printing was "CopyBond SF-70NA" (manufactured by Sharp Corporation, 75 g / m²). 2 ) was used. The fixed images are superimposed, at 100g / cm². 2 Under the applied load, at a temperature of 50°C and a relative humidity of 50%, the printed material was left for two days. After two days, the condition of the printed material was visually observed when it was peeled off, and the heat resistance of the image was evaluated according to the same evaluation criteria as in (1).

[0166] [Table 3]

[0167] [Table 4]

[0168] [Table 5]

[0169] [Table 6]

[0170] Based on the above results, it can be seen that Examples 1 to 17 yield toners with superior image heat resistance compared to Comparative Examples 1 to 4, in which the silica content in the toner particles was too low; Comparative Example 5, in which no toner powder was used; and Comparative Example 6, in which silica was used instead of toner powder. [Industrial applicability]

[0171] 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 electrostatic image developing toner, comprising: step 1: melt-kneading at least a binder resin and a release agent, grinding the resulting pulverized material with silica, then grinding and classifying it to obtain toner powder; step 2: melt-kneading the toner powder obtained in step 1 with at least a binder resin and a release agent, then grinding it; and step 3: mixing the pulverized material obtained in step 2 with silica, then grinding and classifying it to obtain toner particles, wherein the silica content in the toner particles is 0.5% by mass or more and 15% by mass or less.

2. The BET specific surface area of ​​silica is 10 m². ２ / g or more 350m ２ A method for manufacturing electrostatic image developing toner according to claim 1, wherein the amount is less than or equal to / g.

3. A method for producing electrostatic image developing toner according to claim 1 or 2, wherein the release agent contains a hydrocarbon wax and / or a synthetic ester wax.

4. A method for producing electrostatic image developing toner according to claim 1 or 2, wherein the content of toner powder is 5% by mass or more and 30% by mass or less in the toner particles.

5. A method for producing electrostatic image developing toner according to claim 1 or 2, wherein the toner powder is the powder removed by lower-limit classification during classification in step 1.

6. Volume median particle size of toner particles (D ５０Ｘ ) and the medium volume particle size of the toner powder (D ５０Ｙ ) difference (D ５０Ｘ ―D ５０Ｙ A method for manufacturing electrostatic image developing toner according to claim 1 or 2, wherein the diameter of the ) is 1.0 μm or larger.

7. Furthermore, the method for producing electrostatic image developing toner according to claim 1 or 2, further comprising step 4 of mixing the toner particles obtained in step 3 with an external additive.

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