Toner for developing electrostatic images

Abstract

This relates to a toner for electrostatic image development that is excellent at suppressing photoreceptor fogging. [Solution] A toner for developing electrostatic images, comprising toner matrix particles containing a crystalline polyester resin C and an amorphous polyester resin A, and an external additive, wherein the crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component containing 60 mol% or more of ethylene glycol, and the external additive contains silica S1 with a number average particle diameter of 20 nm to 70 nm surface-treated with silicone oil, and silica S2 with a number average particle diameter of 20 nm to 70 nm surface-treated with a hydrophobic treatment agent other than silicone oil.

Description

[Technical Field]

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

[0002] In electrostatic developer toners, external additives are generally added to the toner particles from the viewpoint of fluidity and transferability, and toners using two or more types of particles as external additives are being considered from the viewpoint of charge stability and cleaningability (see Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-180146 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] External additives are prone to causing photoreceptor fogging after continuous printing, and in particular, when crystalline polyester resin is used as a binder resin to improve the low-temperature fixing properties of toner, the deterioration of image quality due to photoreceptor fogging is significant.

[0005] This invention relates to a toner for electrostatic image development that is excellent at suppressing photoreceptor fogging. [Means for solving the problem]

[0006] The present invention relates to a toner for electrostatic image development containing toner matrix particles containing a crystalline polyester resin C and an amorphous polyester resin A, and an external additive, wherein the crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component containing 60 mol% or more of ethylene glycol, and the external additive contains silica S1 with a number average particle diameter of 20 nm to 70 nm surface-treated with silicone oil, and silica S2 with a number average particle diameter of 20 nm to 70 nm surface-treated with a hydrophobic treatment agent other than silicone oil. [Effects of the Invention]

[0007] The electrostatic image developing toner of the present invention exhibits excellent effects in suppressing photoreceptor fogging. [Modes for carrying out the invention]

[0008] The electrostatic image developing toner of the present invention contains toner matrix particles containing a crystalline polyester resin C and an amorphous polyester resin A, and an external additive. A key feature of the toner is that it contains a crystalline polyester resin C obtained using ethylene glycol, and as an external additive, silica S1 of a predetermined particle size surface-treated with silicone oil, and silica S2 of a predetermined particle size surface-treated with a hydrophobic treatment agent other than silicone oil. The reason why the effects of the present invention are achieved is not clear, but it is presumed to be as follows. Note that the following mechanism is a hypothesis and is not limited thereto.

[0009] Toners containing crystalline polyester resin are susceptible to melting of the resin in high-temperature, high-humidity environments, exposing it to the surface of toner particles. This softens the particle surface and facilitates aggregation between particles due to moisture in the atmosphere. Normally, hydrophobic silica particles are used as an external additive to coat the toner surface, creating a spacer effect between toner particles and improving toner fluidity. However, in high-temperature, high-humidity environments, the silica becomes embedded within the toner due to softening of the toner surface by heat and collisions between toner particles, preventing the spacer effect from occurring and reducing fluidity. As a result, toner is more likely to adhere to non-image areas during development, leading to photoreceptor fogging. However, in the toner of the present invention, the crystalline polyester resin C containing ethylene glycol as the alcohol component has high crystallinity and has an ester group structure with two carbon atoms in close proximity. Therefore, it readily interacts with silica particles surface-treated with silicone oil which has many oxygen atoms, and its crystallinity is less likely to be impaired even in high temperature and high humidity environments, thus suppressing the embedding of silica particles. On the other hand, compared to hydrophobic treatment with silicone oil, the fluidity of the added toner is low, possibly due to its hydrophilic properties, when using silicone oil for hydrophobic treatment. Reducing the particle size of the added additive is effective in improving fluidity, but this increases the frequency of contact between toner particles, making them more prone to excessive charging and thus increasing the likelihood of photoreceptor fogging. Therefore, in this invention, by using medium-particle size silica S1 surface-treated with silicone oil and medium-particle size silica S2 surface-treated with a hydrophobic treatment agent other than silicone oil in combination, the embedding of silica particles is suppressed, the fluidity of the toner is improved, and photoreceptor fogging is suppressed even in high-temperature and high-humidity environments.

[0010] Crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component, with the alcohol component mainly containing ethylene glycol.

[0011] The ethylene glycol content in the alcohol component is 60 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, and 100 mol% or less, from the viewpoint of low-temperature fixability and hydrophilicity. If the alcohol component includes an aliphatic monoalcohol, the ethylene glycol content is preferably 99 mol% or less, more preferably 98 mol% or less.

[0012] Other alcohol components besides ethylene glycol include aliphatic diols other than ethylene glycol such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol; aromatic diols such as alkylene oxide adducts of bisphenol A; trivalent or higher alcohols such as bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, and trimethylolpropane.

[0013] The carboxylic acid component preferably contains an aliphatic dicarboxylic acid compound.

[0014] Aliphatic dicarboxylic acid compounds include succinic acid (4 carbon atoms), fumaric acid (4 carbon atoms), adipic acid (6 carbon atoms), suberic acid (8 carbon atoms), azelaic acid (9 carbon atoms), sebacic acid (10 carbon atoms), dodecanediic acid (12 carbon atoms), tetradecanediic acid (14 carbon atoms), anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms. In this invention, carboxylic acid compounds include not only free acids but also anhydrides that decompose during the reaction to produce acids, and alkyl esters with 1 to 3 carbon atoms.

[0015] From the perspective of hydrophobicity, the number of carbon atoms in the aliphatic dicarboxylic acid-based compound is preferably 6 or more, more preferably 9 or more, and from the perspective of low-temperature fixing property, it is preferably 14 or less, more preferably 12 or less. Here, when the aliphatic dicarboxylic acid-based compound is an alkyl ester, the number of carbon atoms in the alkyl group is not included in the above number of carbon atoms.

[0016] The content of the aliphatic dicarboxylic acid-based compound is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, still more preferably 80 mol% or more in the carboxylic acid component, and is 100 mol% or less. When the carboxylic acid component contains an aliphatic monocarboxylic acid-based compound, it is preferably 99 mol% or less, more preferably 98 mol% or less.

[0017] Examples of other carboxylic acid components include aromatic dicarboxylic acid-based compounds such as phthalic acid, isophthalic acid, and terephthalic acid, and polyvalent carboxylic acid-based compounds such as trimellitic acid and pyromellitic acid.

[0018] From the perspective of improving hydrophobicity, it is further preferable that the alcohol component and / or carboxylic acid component of the crystalline polyester resin C contains a monofunctional monomer.

[0019] From the perspective of improving crystallinity, the monofunctional monomer preferably contains an aliphatic monocarboxylic acid-based compound and / or an aliphatic monoalcohol, and more preferably contains an aliphatic monocarboxylic acid-based compound.

[0020] Examples of the aliphatic monoalcohol contained in the alcohol component include caprylic alcohol, capric alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, behenyl alcohol, and the like.

[0021] From the viewpoint of hydrophobicity, the carbon number of the aliphatic monoalcohol is preferably 6 or more, more preferably 9 or more, even more preferably 10 or more, and even more preferably 12 or more, and from the viewpoint of low-temperature fixability, it is preferably 24 or less, more preferably 23 or less, and even more preferably 22 or less.

[0022] Examples of aliphatic monocarboxylic acid compounds included in the carboxylic acid component include aliphatic monocarboxylic acids such as caproic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, as well as alkyl esters of these acids in which the alkyl group has 1 to 3 carbon atoms.

[0023] From the viewpoint of hydrophobicity, the carbon number of the aliphatic monocarboxylic acid compound is preferably 6 or more, more preferably 9 or more, and even more preferably 10 or more. From the viewpoint of low-temperature fixability, it is preferably 24 or less, more preferably 23 or less, and even more preferably 22 or less. Here, the carbon number of the alkyl group when the aliphatic monocarboxylic acid compound is an alkyl ester is not included in the above carbon number.

[0024] The content of monofunctional monomers is preferably 2 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more, of the total amount of alcohol and carboxylic acid components, and from the viewpoint of preservation, preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol% or less.

[0025] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol and carboxylic acid components.

[0026] The equivalent ratio of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component (COOH group / OH group) is preferably 0.8 or higher, more preferably 0.9 or higher, from the viewpoint of electrostatic stability, and preferably 1.2 or lower, more preferably 1.1 or lower, from the viewpoint of low-temperature fixability.

[0027] Crystalline polyester resin C 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., preferably at a temperature of 120°C to 230°C.

[0028] Examples of esterification catalysts include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(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.

[0029] 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.

[0030] The softening point of the crystalline polyester resin C is preferably 50°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher, from the viewpoint of electrostatic stability, and preferably 120°C or lower, more preferably 110°C or lower, from the viewpoint of low-temperature fixability.

[0031] The crystallinity of a resin is expressed by a crystallinity index, which is defined by the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, i.e., the value of [softening point / maximum endothermic peak temperature]. The crystalline resin is a resin having a crystallinity index of 0.6 or higher, preferably 0.7 or higher, more preferably 0.9 or higher, and 1.4 or lower, preferably 1.2 or lower, more preferably 1.1 or lower. On the other hand, amorphous resins are those in which no endothermic peak is observed, or, if observed, resins with a crystallinity index greater than 1.4, preferably greater than 1.5, more preferably 1.6 or higher, or resins with an index less than 0.6, preferably 0.5 or lower. The crystallinity of a resin can be adjusted by the type and ratio of raw material monomers, as well as the manufacturing conditions (e.g., reaction temperature, reaction time, cooling rate). The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In crystalline resins, the maximum endothermic peak temperature is defined as the melting point.

[0032] The melting point of the crystalline polyester resin C is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of storage properties, and preferably 130°C or lower, more preferably 120°C or lower, from the viewpoint of low-temperature fixability.

[0033] From the viewpoint of electrostatic stability, the acid value of crystalline polyester resin C is preferably 1 mg KOH / g or more, more preferably 3 mg KOH / g or more, and preferably 20 mg KOH / g or less, more preferably 15 mg KOH / g or less.

[0034] The content of crystalline polyester resin C is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more, of the total amount of crystalline polyester resin C and amorphous polyester resin A, from the viewpoint of low-temperature fixability, 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 storage and electrostatic stability.

[0035] 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.

[0036] 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.

[0037] The alkylene oxide adduct of bisphenol A is given by formula (I):

[0038] [ka]

[0039] (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.

[0040] 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.

[0041] 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.

[0042] Examples of carboxylic acid components include aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and trivalent or higher carboxylic acid compounds.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] Furthermore, the alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monohydric carboxylic acid compound, as appropriate.

[0047] 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.

[0048] The polycondensation reaction conditions between the alcohol component and the carboxylic acid component of the amorphous polyester resin are the same as those for the crystalline polyester resin, except that the preferred reaction temperature is 160°C or higher, more preferably 180°C or higher, and 250°C or lower, more preferably 240°C or lower.

[0049] 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").

[0050] 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.

[0051] 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.

[0052] In alkyl (meth)acrylate esters used as raw material monomers for styrene-based resins, the number of carbon atoms in the alkyl group is preferably 7 or more, more preferably 8 or more, and preferably 12 or less, and more preferably 10 or less, from the viewpoint of improving the low-temperature fixability 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] (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.

[0061] (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.

[0062] (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.

[0063] In method (i) above, a pre-polymerized polycondensation 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.

[0064] Methods (i) to (iii) described above are preferably carried out in the same container.

[0065] 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.

[0066] The softening point of amorphous polyester resin A is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, from the viewpoint of 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.

[0067] Furthermore, the amorphous polyester resin A 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.

[0068] 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 130°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.

[0069] 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.

[0070] The mass ratio of resin AH to resin AL (resin AH / resin AL) is preferably 50 / 50 or more, more preferably 60 / 40 or more, even more preferably 65 / 35 or more, and preferably 90 / 10 or less, more preferably 80 / 20 or less, and even more preferably 75 / 25 or less.

[0071] The glass transition temperature of amorphous polyester resin A 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.

[0072] The acid value of amorphous polyester resin A is preferably 10 mg KOH / g or more, more preferably 15 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.

[0073] The content of amorphous polyester resin A is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and preferably 97% by mass or less, more preferably 95% by mass or less, and even more preferably 92% by mass or less, from the viewpoint of low-temperature fixability and storage properties, relative to the total amount of crystalline polyester resin C and amorphous polyester resin A.

[0074] The mass ratio of crystalline polyester resin C to amorphous polyester resin A (crystalline polyester resin C / amorphous polyester resin A) is preferably 3 / 97 or higher, more preferably 5 / 95 or higher, even more preferably 8 / 92 or higher, and preferably 30 / 70 or lower, more preferably 25 / 75 or lower, and even more preferably 20 / 80 or lower, from the viewpoint of low-temperature fixability and storage properties.

[0075] In toner, crystalline polyester resin C and amorphous polyester resin A are included as binder resins (binding agents).

[0076] The total content of crystalline polyester resin C and amorphous polyester 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, and 100% by mass or less.

[0077] Other binder resins include vinyl resins such as styrene-acrylic resin, polyamide resin, epoxy resin, polycarbonate resin, polyurethane resin, and composite resins containing two or more of these resins.

[0078] Furthermore, the binder resin content is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably less than 100% by mass, more preferably 98% by mass or less, and even more preferably 95% by mass or less, in the toner mother particles.

[0079] The electrostatic image developing toner of the present invention may contain additives other than the binder resin, such as colorants, release agents, charge control agents, magnetic powders, flowability enhancers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, and cleaning properties enhancers.

[0080] 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.

[0081] From the viewpoint of improving the image density of the toner and its low-temperature fixability, the amount of colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the binder resin.

[0082] Examples of mold release agents include hydrocarbon waxes and their oxides, such as polypropylene wax, polyethylene wax, ethylene propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; ester waxes such as carnauba wax, montane wax and their deoxidizing waxes, and fatty acid ester waxes; and fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts, etc., which can be used individually or in combination of two or more.

[0083] The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of storage properties, and preferably 160°C or lower, more preferably 140°C or lower, even more preferably 120°C or lower, and even more preferably 110°C or lower, from the viewpoint of low-temperature fixing properties.

[0084] The release agent content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less, per 100 parts by mass of binder resin, from the viewpoint of the electrostatic stability of the toner and its dispersibility in the binder resin.

[0085] 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.

[0086] 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.).

[0087] 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.

[0088] From the viewpoint of the charge stability of the toner, the content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of the binder resin. If the charge control agent is a resin (polymer type), it is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the binder resin.

[0089] Volume median particle size of toner matrix particles (D 50 The volume median particle size (D) is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. 50 ) refers to the particle size at which the cumulative volume frequency, calculated using volume fractions, accounts for 50% of the total volume frequency, starting from the smallest particle size.

[0090] The external additives include two different hydrophobic agents, silica S1 surface-treated with silicone oil, and silica S2 surface-treated with a hydrophobic agent other than silicone oil.

[0091] Other hydrophobic treatment agents besides silicone oil include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0092] The number-average particle diameters of silica S1 and silica S2 are, from the viewpoint of chargeability, 20 nm or more, preferably 25 nm or more, and more preferably 28 nm or more, and from the viewpoint of chargeability and fluidity, 70 nm or less, preferably 55 nm or less, and more preferably 45 nm or less.

[0093] The silica S1 content is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.4 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 1.2 parts by mass or less, and even more preferably 0.8 parts by mass or less, per 100 parts by mass of toner matrix particles.

[0094] The silica S2 content is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.4 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 1.2 parts by mass or less, and even more preferably 0.8 parts by mass or less, per 100 parts by mass of toner matrix particles.

[0095] The mass ratio of silica S1 to silica S2 (S1 / S2) is preferably 20 / 80 or more, more preferably 30 / 70 or more, even more preferably 40 / 60 or more, and preferably 80 / 20 or less, more preferably 70 / 30 or less, and even more preferably 60 / 40 or less.

[0096] The total content of silica S1 and silica S2 is preferably 0.3 parts by mass or more, more preferably 0.4 parts by mass or more, even more preferably 0.8 parts by mass or more, and preferably 3.0 parts by mass or less, more preferably 2.4 parts by mass or less, and even more preferably 1.6 parts by mass or less, per 100 parts by mass of toner matrix particles.

[0097] The external additive may contain external additives other than silica S1 and silica S2, but the total content of silica S1 and silica S2 in the external additive is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less.

[0098] Other external additives include inorganic fine particles such as silica other than silica S1 and silica S2, alumina, titania, zirconia, tin oxide, and zinc oxide, as well as organic fine particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles, and hydrophobized versions thereof.

[0099] The toner of the present invention may be obtained by any of the conventionally known methods, such as the melt-kneading method, the emulsification-coagulation method, or the suspension polymerization method, but pulverized toner is preferred, and from the viewpoint of the miscibility of the toner raw materials, pulverized toner obtained by the melt-kneading method, that is, toner obtained by a method including the steps of melt-kneading the raw materials, pulverizing the resulting mixture to obtain toner mother particles, and mixing the toner mother particles with an external additive is more preferred. Specifically, for example, a binder resin containing a crystalline polyester resin C and an amorphous polyester resin A, and, if necessary, raw materials such as a colorant, release agent, and charge control agent, can be uniformly mixed in a mixer such as a Henschel mixer, then melt-kneaded in a closed-type kneader, a single-screw or twin-screw extruder, an open-roll type kneader, etc., cooled, pulverized, and classified, and the obtained toner mother particles can be mixed with an external additive to produce the toner.

[0100] External additive treatment, which involves mixing toner matrix particles with external additives, can be carried out according to conventional methods, and a mixer such as a Henschel mixer can be used. Silica S1 and silica S2 may be mixed with the toner matrix particles at the same time or separately, but the former is preferred from the viewpoint of electrostatic stability.

[0101] The toner 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]

[0102] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way by these examples. The physical properties of resins, etc., can be measured by the following methods.

[0103] [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.

[0104] [Maximum peak temperature of endothermic resin] 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 and cooled from room temperature (25°C) to 0°C at a rate of 10°C / min, and maintained at 0°C for 1 minute. Then, measurements are taken at a rate of 10°C / min. Among the observed endothermic peaks, the temperature of the peak with the largest peak area is defined as the maximum endothermic peak temperature. For crystalline resins, the maximum endothermic peak temperature is defined as the melting point.

[0105] [Glass transition temperature of resins] 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 to 0°C at a rate of 10°C / min. Next, the sample is heated at a rate of 10°C / min and the endothermic peak is measured. The temperature at the intersection of the extension of the baseline below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the peak apex is defined as the glass transition temperature.

[0106] [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 a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for amorphous resins, and to a mixed solvent of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins.

[0107] [Melting point of release agent] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a rate of 10°C / min. Next, the sample is heated again at a rate of 10°C / min, the amount of heat is measured, and the maximum peak temperature of endothermic heating is defined as the melting point.

[0108] [Medium volume particle size of resin particles, colorant particles, and mold release agent particles] (1) Measuring device: Laser diffraction particle size analyzer "LA-920" (manufactured by Horiba, Ltd.) (2) Measurement conditions: Take the sample dispersion into a measuring cell, add distilled water, and measure the volume mid-particle size (D) at a temperature where the absorbance is within the appropriate range. 50 ) Measure.

[0109] [Solid content concentration of resin dispersion, colorant dispersion, and mold release agent dispersion] Using the infrared moisture meter "FD-230" (manufactured by Kett Scientific Research Institute Co., Ltd.), 5g of the sample to be measured was dried at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, variation range 0.05%), and the moisture content (mass%) of the dispersion was measured. The solid content concentration was calculated according to the following formula. Solid concentration (mass%) = 100-moisture (mass%)

[0110] [Medium particle size by volume of aggregated particles] • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte solution to adjust the concentration to one that could measure the particle size of 30,000 particles in 20 seconds. Then, the 30,000 particles were measured, and the volume median particle size (D) was determined from the particle size distribution. 50 )

[0111] [Medium volume particle size of toner matrix particles (D 50 )〕 • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer III (registered trademark) 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 measurement sample to 5 mL of the dispersion liquid, disperse it for 1 minute using an ultrasonic disperser (machine name: US-1 manufactured by SND Co., Ltd., output: 80 W), then add 25 mL of the electrolyte solution, and further disperse it for 1 minute using the ultrasonic disperser to prepare a sample dispersion liquid. ·Measurement conditions: By adding the sample dispersion liquid to 100 mL of the electrolyte solution, adjust the concentration to a level where the particle sizes of 30,000 particles can be measured in 20 seconds, then measure 30,000 particles, and obtain the volume median particle size (D 50 ) from its particle size distribution.

[0112] 〔Circularity of toner mother particles〕 ·Measuring device: Flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) ·Preparation of dispersion liquid: Prepare a dispersion liquid of toner particles by diluting it with deionized water so that the solid content concentration becomes 0.001 to 0.05 mass%. ·Measurement mode: HPF measurement mode

[0113] 〔Number average particle diameter of external additive〕 Measure the particle sizes (average value of the major axis and minor axis) of 500 particles from a scanning electron microscope (SEM) photograph, and use their number average value.

[0114] Production example 1 of alkenyl succinic anhydride (1) Using propylene tetramer (manufactured by Nippon Oil Corporation, trade name: "Light Tetramer"), it was fractionated under heating conditions of 183 to 208 °C to obtain an alkylene compound (a). The obtained alkylene compound (a) had 40 peaks in the following gas chromatography-mass spectrometry. The distribution of the alkylene compound was measured according to the analysis by gas chromatography-mass spectrometry of alkylene compound A in JP-A-2014-013384, and C9H 18 : 0.5 mass%, C 10 H 20 : 4 mass%, C 11 H 22 : 20 mass%, C 12 H 24 : 66 mass%, C 13 H 26 : 9 mass%, C14 H 28 The concentration was 0.5% by mass (6 peaks corresponding to alkylene compounds with 9 to 14 carbon atoms).

[0115] (2) 542.4 g of alkylene compound (a), 157.2 g of maleic anhydride, 0.4 g of the antioxidant "Cherex-O" (manufactured by SC Organic Chemicals Co., Ltd., triisooctyl phosphite), and 0.1 g of butyl hydroquinone as a polymerization inhibitor were charged into a 1 L autoclave manufactured by Nitto High Pressure Co., Ltd., and pressurized nitrogen purging (0.2 MPaG) was repeated three times. After stirring was started at 60°C, the temperature was raised to 230°C over 1 hour and the reaction was carried out for 6 hours. The pressure at the reaction temperature was 0.3 MPaG. After the reaction was complete, the mixture was cooled to 80°C and returned to atmospheric pressure (101.3 kPa) and transferred to a 1 L four-necked flask. The temperature was raised to 180°C while stirring, and the remaining alkylene compound was removed by distillation at 1.3 kPa over 1 hour. Subsequently, the mixture was cooled to room temperature (25°C) and then returned to atmospheric pressure (101.3 kPa) to obtain 406.1 g of the target product, alkenyl succinic anhydride A. The average molecular weight of alkenyl succinic anhydride A, calculated from its acid value, was 268.

[0116] Resin manufacturing example 1 The alcohol components, carboxylic acid components other than trimellitic anhydride, esterification catalyst, and polymerization inhibitor shown in Table 1 were placed in a 10-liter four-necked flask equipped with a dehydration tube with a nitrogen inlet tube, a stirrer, and a thermocouple. The mixture was heated to 230°C in a mantle heater under a nitrogen atmosphere and polycondensed for 7 hours. After that, the temperature was lowered to 200°C, trimellitic anhydride was added, and the temperature was raised to 210°C to carry out the polycondensation reaction until the softening point reached the temperature shown in Table 1, thereby obtaining amorphous polyester resins (resins AH1, AH2).

[0117] [Table 1]

[0118] Resin manufacturing example 2 The raw material monomers for polyester resins other than trimellitic anhydride, and the esterification catalyst shown in Table 2, were placed in a 10-liter four-necked flask equipped with a dehydration tube with a nitrogen inlet, a stirrer, and a thermocouple. The mixture was heated to 160°C in a mantle heater under a nitrogen atmosphere, and then polymerized by dropwise adding a mixture of the raw material monomers for styrene resin, both reactive monomers, and a polymerization initiator over 1 hour. The mixture was heated to 200°C and allowed to mature for 1 hour to generate styrene resin in the reaction system. After that, the mixture was heated to 230°C over 1 hour to confirm that all solid monomers had melted. Subsequently, the pressure was reduced to 8 kPa and dehydration condensation was carried out for 1 hour, then the temperature was lowered to 210°C, trimellitic anhydride was added, and the reaction was continued for another hour. The pressure was reduced to 8 kPa and the reaction was continued until the softening point reached the temperature shown in Table 2 to obtain an amorphous composite resin (resin AL1).

[0119] [Table 2]

[0120] Resin manufacturing example 3 The alcohol and carboxylic acid components shown in Table 3 were placed in a 10-liter four-necked flask equipped with a dehydration tube with a nitrogen inlet, a stirrer, and a thermocouple. The mixture was heated to 200°C over 8 hours in a mantle heater under a nitrogen atmosphere. Subsequently, an esterification catalyst was added, and the reaction was carried out at 8 kPa until the softening point reached the temperature shown in Table 3, yielding crystalline polyester resins (resins C1-C5).

[0121] [Table 3]

[0122] Example 1 65 parts by mass of resin A1, 25 parts by mass of resin B1, 10 parts by mass of resin C2, 5 parts by mass of coloring agent "Mogul-L" (manufactured by Cabot Corporation, carbon black), 1 part by mass of charge control agent "T-77" (manufactured by Hodogaya Chemical Co., Ltd.), and 3 parts by mass of mold release agent "WAX-C1" (manufactured by Kato Yoko Co., Ltd., carnauba wax, melting point: 83℃) were thoroughly mixed in a Henschel mixer, and then melt-kneaded using a co-rotating twin-screw extruder "PCM-30" (manufactured by Ikegai Co., Ltd.). The operating conditions for the co-rotating twin-screw extruder were a barrel setting temperature of 100℃, 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. The resulting mixture is cooled and then processed using an IDS grinding and classifying machine (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to determine the medium volume particle size (D 50 The particles were crushed and classified so that their size was 7.0 μm to obtain toner matrix particles.

[0123] To 100 parts by mass of the obtained toner matrix particles, 0.5 parts by mass of "NY-50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil, number average particle size: 30 nm) and 0.5 parts by mass of "TG-5110" (hydrophobic silica, manufactured by Cabot Corporation, hydrophobic treatment agent: HMDS, number average particle size: 37 nm) were added as external additives, and the mixture was treated with external additives by mixing at 3000 r / min for 3 minutes using a Henschel mixer to obtain toner.

[0124] Examples 2-12, Comparative Examples 1-5 Toner was obtained in the same manner as in Example 1, except that the types and amounts of crystalline polyester resin and external additives were changed as shown in Tables 5 and 6.

[0125] Example 13 Toner was obtained in the same manner as in Example 1, except that a continuous two-roll open-roll mixer "Nidex" (manufactured by Nippon Coke Industries Co., Ltd.) was used for melt-mixing instead of a co-rotating twin-screw extruder. The continuous two-roll open-roll mixer 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 75 r / min (peripheral speed 33 m / min) for the high-speed roll (front roll), a rotation speed of 50 r / min (peripheral speed 22 m / min) for the low-speed roll (rear roll), and a roll gap of 0.1 mm. The heating and cooling media temperatures inside the rolls were set to 140°C on the raw material input side and 110°C on the mixed material discharge side of the high-speed roll, and to 65°C on the raw material input side and 30°C on the mixed 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 5 minutes.

[0126] Example 14 [Preparation of resin dispersion] In a 3-liter container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 130 g (65 parts by mass) of resin AH2, 50 g (25 parts by mass) of resin AL1, 20 g (10 parts by mass) of resin C2, and 200 g of methyl ethyl ketone were placed and dissolved at 73°C for 2 hours. To the resulting solution, a 5% by mass aqueous sodium hydroxide solution was added to achieve a degree of neutralization of 60 mol% relative to the acid value of the resin, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, 700 g of deionized water was added over 50 minutes while stirring at 200 r / min to induce phase inversion emulsification. The resulting solution was then maintained at 73°C, and methyl ethyl ketone was removed under reduced pressure to obtain a dispersion. Subsequently, the dispersion was cooled to 30°C while continuing to stir, and then deionized water was added to achieve a solid content concentration of 20% by mass to obtain a resin dispersion.

[0127] <Preparation of colorant dispersion> In a 1-liter beaker, 116.2 g of the coloring agent "Mogul-L" (manufactured by Cabot Corporation), 154.9 g of the anionic surfactant "Neoperex® G-15" (manufactured by Kao Corporation, 15% by mass sodium dodecylbenzenesulfonate aqueous solution), and 260 g of deionized water were mixed and dispersed at room temperature for 3 hours using a homogenizer. Then, deionized water was added to obtain a coloring agent dispersion with a solid content concentration of 20% by mass. The median particle size (D) of the coloring agent particles in the obtained dispersion was measured. 50 The wavelength was 118 nm.

[0128] <Preparation of mold release agent dispersion> 50g of the release agent "WAX-C1" (manufactured by Kato Yoko Co., Ltd., carnauba wax, melting point: 83℃), 5g of a cationic surfactant (manufactured by Kao Corporation, product name: Sanizol B50), and 200g of deionized water were heated to 95℃, and the release agent was dispersed using a homogenizer. After further dispersion treatment with a pressure-discharge type homogenizer, deionized water was added to obtain a release agent dispersion with a solid content of 20% by mass. The median particle size (D) of the release agent particles in the obtained dispersion was measured. 50 The wavelength was 550 nm.

[0129] <Agglomeration process> In a 3-liter four-necked flask equipped with a reflux condenser, stirrer, and thermocouple, 549 g of resin dispersion, 23 g of colorant dispersion, 16 g of mold release agent dispersion, and 3.3 g of 15% by mass sodium dodecylbenzenesulfonate aqueous solution "Neoperex G-15" (manufactured by Kao Corporation, anionic surfactant) were added and mixed at a temperature of 25°C. Next, while stirring the resulting mixture, a solution prepared by dissolving 43 g of ammonium sulfate in 980 g of deionized water and adding a 4.8% by mass potassium hydroxide aqueous solution to adjust the pH to 8.2 was added dropwise over 10 minutes at 25°C, and the temperature was raised to 58°C over 2 hours to determine the volume-median particle size (D) of the aggregated particles. 50 The mixture was maintained at 58°C until the particle size reached 7.0 μm, and a dispersion of aggregated particles was obtained.

[0130] <Fusing process> To the resulting dispersion of aggregated particles, 22 g of polyoxyethylene lauryl ether sodium sulfate "Emal E-27C" (manufactured by Kao Corporation, anionic surfactant, effective concentration 27% by mass) and 1100 g of deionized water were added. The mixture was then heated to 75°C over 1 hour and maintained at 75°C until the circularity reached 0.970, thereby obtaining a dispersion of fused particles in which the aggregated particles had fused together.

[0131] The resulting dispersion of fused particles was cooled to 30°C, and the dispersion was filtered by suction to separate the solid components. The mixture was then washed with deionized water at 25°C and filtered by suction at 25°C for 2 hours. Subsequently, the toner matrix particles were obtained by vacuum drying at 33°C for 24 hours using a vacuum constant-temperature dryer "DRV622DA" (manufactured by ADVANTEC).

[0132] To 100 parts by mass of the obtained toner matrix particles, 0.5 parts by mass of "NY-50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil, number average particle size: 30 nm) and 0.5 parts by mass of "TG-5110" (hydrophobic silica, manufactured by Cabot Corporation, hydrophobic treatment agent: HMDS, number average particle size: 37 nm) were added as external additives, and the mixture was treated with external additives by mixing at 3000 r / min for 3 minutes using a Henschel mixer to obtain toner.

[0133] Table 4 shows the details of the external additives used in the examples and comparative examples.

[0134] [Table 4]

[0135] Test example [Photoreceptor haze under high-temperature conditions] A modified non-magnetic single-component developer unit, the "Monochrome LED Printer B432dnw" (manufactured by OKI Electric Industry Co., Ltd.), with adjustable printing speed, was loaded with 50g of toner. Under conditions of 35°C and 80% relative humidity, 2000 images with a print density of 0.3% were printed at a speed equivalent to 30 A4 sheets per minute. A solid white image was printed every 500 sheets, and the power was cut off during printing. Afterward, the toner on the photoreceptor surface was adhered using "Scotch® Mending Tape 810" (manufactured by 3M Japan Ltd., width: 18mm), and the color density was measured using an image density meter "exact" (manufactured by X-Rite). The difference between the color density of the tape before toner adhesion and the color density of the tape itself was calculated, and the average of four measurements from the 500th to the 2000th sheet was determined. The results are shown in Tables 5 and 6. A smaller value indicates better suppression of fogging.

[0136] [Table 5]

[0137] [Table 6]

[0138] From the above results, it can be seen that the toners of Examples 1 to 14 suppress the occurrence of photoreceptor fogging compared to Comparative Example 1, which does not use ethylene glycol as the alcohol component of the crystalline polyester resin; Comparative Examples 2 and 4, which use silica with a particle size larger than specified; Comparative Example 3, which does not use silica surface-treated with silicone oil; and Comparative Example 5, which uses only silica surface-treated with silicone oil. [Industrial applicability]

[0139] The electrostatic image developing toner of the present invention is suitably used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like.

Claims

1. A toner for developing electrostatic images, comprising toner matrix particles containing a crystalline polyester resin C and an amorphous polyester resin A, and an external additive, wherein the crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component containing 60 mol% or more of ethylene glycol, and the external additive contains silica S1 with a number average particle diameter of 20 nm to 70 nm surface-treated with silicone oil, and silica S2 with a number average particle diameter of 20 nm to 70 nm surface-treated with a hydrophobic treatment agent other than silicone oil.

2. The toner for developing electrostatic images according to claim 1, wherein the total content of silica S1 and silica S2 is 0.3 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of toner matrix particles.

3. The electrostatic image developing toner according to claim 1 or 2, wherein the mass ratio of silica S1 to silica S2 is 20 / 80 or more and 80 / 20 or less.

4. The electrostatic image developing toner according to claim 1 or 2, wherein the alcohol component and / or carboxylic acid component of the crystalline polyester resin C contains a monofunctional monomer.

Images