Toner binder resin

Abstract

To provide a binder resin for toners having excellent low-temperature fixability, hot off-set resistance, heat-resistant storage properties, and charging stability.SOLUTION: A binder resin for toners contains a composite resin in which a styrene acrylic resin unit and a polyester resin unit are bonded to each other via a covalent bond. A styrene acrylic resin (A) constituting the styrene acrylic resin unit has an acid value of 40 mgKOH / g or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a binder resin used in toners used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like. [Background technology]

[0002] In recent years, in the field of electrophotography, the development of electrostatic image developing toners that support high-resolution and high-speed printing has been required as electrophotographic systems have advanced. In response to these demands, polyester resin has been proposed as a binder resin for toners that exhibits excellent low-temperature fixing properties. Generally, the minimum fixing temperature falls within the temperature range from the low-temperature offset occurrence temperature to the high-temperature offset occurrence temperature. Therefore, the usable temperature range for binder resins is from the minimum fixing temperature to the high-temperature offset occurrence temperature. By lowering the minimum fixing temperature and raising the high-temperature offset occurrence temperature as much as possible, the usable fixing temperature can be lowered and the usable temperature range can be expanded, thus meeting the requirements for energy saving and high-speed fixing. For this reason, there is a high demand for binder resins and toners for toners that have excellent low-temperature fixing properties and offset resistance. However, while polyester resins have excellent low-temperature fixing properties, they have the problem of being prone to the offset phenomenon.

[0003] In such a situation, in Patent Document 1, the binder resin of toner particles is, as a low softening point resin, a resin obtained by addition-polymerizing a vinyl monomer in the presence of a polycondensation monomer and then polycondensing the polycondensation monomer after the addition-polymerization reaction is completed, or a resin obtained by polycondensing a polycondensation monomer in the presence of a vinyl resin obtained by addition-polymerizing a vinyl monomer, and, as a high softening point resin, a resin obtained by adding, mixing, and addition-polymerizing a vinyl monomer to a polycondensation resin obtained by polycondensing a polycondensation monomer. The toner is described as containing these resins, having a softening point of the low softening point resin that is 5°C or more lower than the softening point of the high softening point resin, and having a mass ratio of the low softening point resin to the high softening point resin within a predetermined range, and it is disclosed that a toner excellent in low-temperature fixing property, high-temperature offset resistance, and developability can be obtained. In Patent Document 2, a toner having toner particles containing a binder resin and a colorant is disclosed. The binder resin is a hybrid resin in which a vinyl polymer unit obtained by polymerizing a vinyl monomer in the absence of a polyester unit and its raw materials is chemically bonded to a polyester unit, and it is disclosed that a toner excellent in low-temperature fixing property, storage stability, and control of toner fusion to a photosensitive drum can be obtained.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the toner disclosed in Patent Document 1, since a vinyl resin obtained by addition-polymerizing a vinyl monomer in the presence of a polycondensation monomer or a polycondensation resin is used, there are problems in controlling the molecular weight and molecular weight distribution and the monomer copolymerizability. Furthermore, in the toner disclosed in Patent Document 2, the acid value of the vinyl polymer constituting the hybrid resin is low, resulting in insufficient hybridization and problems with heat resistance, storage stability, and electrostatic stability. The present invention relates to a binder resin for toner that is excellent in low-temperature fixing properties, hot offset resistance, heat storage resistance, and electrostatic stability, toner for electrostatic image development, and a method for manufacturing the binder resin for toner. [Means for solving the problem]

[0006] The present inventors have focused on the fact that, in a toner binder resin containing a composite resin in which a polyester resin unit with excellent low-temperature fixability and a styrene-acrylic resin unit with excellent electrostatic properties and hot offset resistance are covalently bonded, sufficient compounding with the polyester resin unit can be achieved by optimizing the molecular weight, molecular weight distribution, and monomer copolymerizability of the styrene-acrylic resin constituting the styrene-acrylic resin unit of the composite resin, and by ensuring that it has an acid value of a predetermined value or higher, thereby solving the problems of low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability.

[0007] In other words, the present invention relates to the following embodiments [1] to [3]. [1] A binder resin for toner containing a composite resin in which a styrene-acrylic resin unit and a polyester resin unit are bonded together via covalent bonds, A binder resin for toner, wherein the acid value of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit is 40 mgKOH / g or more. [2] A toner for developing electrostatic images, comprising the toner binder resin described in [1] above. [3] A method for producing a binder resin for toner, which contains a composite resin in which a styrene-acrylic resin unit and a polyester resin unit are bonded together via covalent bonds, Step I: A step to obtain a styrene-acrylic resin (A) by polymerizing raw material monomer (a) in a polymerization system separate from the polymerization system for raw material monomer (b) constituting the polyester resin unit, in the absence of the polyester resin (B) constituting the polyester resin unit, and, Step II: A step to obtain a toner binder resin containing the composite resin by covalently bonding the styrene-acrylic resin (A) and polyester resin (B) obtained in Step I. Includes, A method for producing a binder resin for toner, wherein the acid value of the styrene-acrylic resin (A) is 40 mg KOH / g or more. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a binder resin for toners that is excellent in low-temperature fixing properties, hot offset resistance, heat storage resistance, and electrostatic stability, a toner for electrostatic image development, and a method for manufacturing a binder resin for toners. [Modes for carrying out the invention]

[0009] [Toner binder resin] The toner binder resin of the present invention (hereinafter also referred to as "the binder resin of the present invention") is a toner binder resin containing a composite resin in which a styrene-acrylic resin unit and a polyester resin unit are bonded together via covalent bonds. Furthermore, the acid value of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit is 40 mgKOH / g or higher. The toner of the present invention exhibits low-temperature fixing properties, resistance to hot offset, heat-resistant storage properties, and electrostatic stability.

[0010] The reason why the effects of this invention are obtained is not entirely clear, but it is thought to be as follows. The styrene-acrylic resin unit of the composite resin contained in the binder resin of the present invention is composed of a styrene-acrylic resin obtained in the absence of the polyester resin that constitutes the polyester resin unit and the raw material monomers that constitute the polyester resin. Therefore, since the polymerization site of the raw material monomers of the styrene-acrylic resin is not the polyester resin or polycondensation monomer as in the conventional method, the inherent polymerization performance of the raw material monomers of the styrene-acrylic resin is exhibited, and it is thought that a more uniform styrene-acrylic resin unit can be formed with controlled molecular weight, molecular weight distribution, and copolymerizability of the monomers. Furthermore, by setting the acid value of the styrene-acrylic resin that constitutes the styrene-acrylic resin unit of the composite resin to 40 mgKOH / g or higher, sufficient compounding with the polyester resin that constitutes the polyester resin unit can be achieved. Due to these synergistic effects, it is thought that it is possible to control the molecular motion of the composite resin at low temperatures and the entanglement of polymer chains at high temperatures, resulting in a resin that is low viscosity at low temperatures and highly elastic at high temperatures, that is, a resin in which the increase in viscosity at low temperatures and the decrease in elasticity at high temperatures are suppressed, thereby improving low-temperature fixability, offset resistance, heat storage resistance, and electrostatic stability.

[0011] The definitions of various terms used in this specification are shown below. "Polyester resin" may include a polyester resin that has been modified to the extent that its properties are not substantially impaired. Examples of modified polyester resins include urethane-modified polyester resin, in which the polyester resin is modified with urethane bonds, and epoxy-modified polyester resin, in which the polyester resin is modified with epoxy bonds. "Bisphenol A" refers to 2,2-bis(4-hydroxyphenyl)propane. Examples of "carboxylic acid compounds" include carboxylic acids, their anhydrides, and alkyl esters having 1 to 3 carbon atoms. Note that the number of carbon atoms in the alkyl group of an alkyl ester is not included in the number of carbon atoms in the carboxylic acid compound. "Binding resin" refers to the binding resin component in toner, including the composite resin.

[0012] The toner of the present invention contains a coloring agent and a binder resin. The toner of the present invention contains, for example, toner particles and an external additive. The toner particles preferably contain a colorant and a binder resin. Furthermore, the toner particles may contain, for example, a mold release agent, a colorant derivative, a charge control agent, or other additives.

[0013] <Composite resin> The composite resin is a resin in which styrene-acrylic resin units and polyester resin units are bonded together via covalent bonds. Furthermore, the acid value of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit is 40 mg KOH / g or higher, from the viewpoint of improving low-temperature fixing properties, hot offset resistance, heat storage resistance, and electrostatic stability. Furthermore, the composite formation method by forming a bond via covalent bonding between a styrene-acrylic resin unit and a polyester resin unit can be described as either (i) a polymer reaction between a styrene-acrylic resin (A) constituting the styrene-acrylic resin unit and a polyester resin (B) constituting the polyester resin unit, or (ii) a reaction between a styrene-acrylic resin (A) constituting the styrene-acrylic resin unit and a raw material monomer (b) constituting the polyester resin unit, from the viewpoint of controlling molecular weight, molecular weight distribution, and copolymerizability of monomers to improve low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. Among these, the polymer reaction method (i) described above is preferred from the viewpoint of controlling molecular weight, molecular weight distribution, and copolymerizability of monomers, and improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. In method (i), since the composite method is a polymerization reaction, it is preferable that the polymerization systems of the styrene-acrylic resin (A) and the polyester resin (B) are carried out in independent reaction systems. It is preferable that the polymerization system of the styrene-acrylic resin (A) is of the addition polymerization type, and the polymerization system of the polyester resin (B) is of the polycondensation type. Independent reaction systems mean that the addition polymerization of the styrene-acrylic resin (A) and the polycondensation of the polyester resin (B) are carried out in separate reaction fields. That is, the addition polymerization of the styrene-acrylic resin (A) is carried out in the absence of the polyester resin (B) and the raw material monomer (b) of the polyester resin (B), and the polycondensation of the polyester resin (B) is carried out in the absence of the styrene-acrylic resin (A) and the raw material monomer (a) of the styrene-acrylic resin (A). If the polymerization reactions described above are independent reaction systems, the two polymerization reactions do not need to proceed and complete simultaneously in time. The reaction temperature and time can be appropriately selected according to the respective reaction mechanism to allow the reactions to proceed and complete. Furthermore, in the polymer reaction of method (i), there are no particular restrictions on the method of mixing the styrene-acrylic resin (A) and the polyester resin (B). For example, the polyester resin (B) may be isolated and then mixed with the styrene-acrylic resin (A), or the polyester resin (B) may be added and mixed without isolation.

[0014] [Styrene-acrylic resin (A)] (Raw material monomer (a)) The styrene-acrylic resin (A) constitutes the styrene-acrylic resin unit of the composite resin, with the viewpoint of improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. It is an addition polymerization product of raw material monomer (a) containing a styrene compound and a (meth)acrylic monomer.

[0015] Examples of styrene compounds include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-chlorostyrene, vinylnaphthalene, and other styrene and styrene derivatives, with styrene and α-methylstyrene being preferred.

[0016] Examples of (meth)acrylic monomers include acrylic acid, methacrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, 2-chloroethyl (meth)acrylate, phenyl (meth)acrylate, 2-(dimethylamino)ethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, methyl α-chloroacrylate, and other (meth)acrylic acids and (meth)acrylic acid derivatives. Furthermore, "(meth)acrylic acid ester" indicates that it includes both acrylic acid esters and methacrylic acid esters. Among these, acrylic acid and methacrylic acid are preferred, with acrylic acid being more preferred.

[0017] The raw material monomer (a) may also contain monomers other than styrene compounds and (meth)acrylic monomers. Other monomers include, for example, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; diolefins such as butadiene; halovinyls such as vinyl chloride, vinyl bromide, and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate, vinyl formate, and vinyl caproate; vinyl ethers such as vinyl methyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrole and N-vinylpyrrolidone.

[0018] The raw material monomer (a) preferably comprises one or more styrene compounds selected from styrene and α-methylstyrene, and one or more (meth)acrylic monomers selected from acrylic acid, methacrylic acid, methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, n-butyl methacrylate, and 2-hydroxyethyl methacrylate, and may further contain other monomers such as propylene.

[0019] The content of styrene compounds in the raw material monomer (a) constituting the styrene-acrylic resin (A), or the content of constituent units derived from styrene compounds in the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit, is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, and preferably 98% by mass or less, more preferably 96% by mass or less, and even more preferably 94% by mass or less. The content of (meth)acrylic monomers in the raw material monomer (a) constituting the styrene-acrylic resin (A), or the content of constituent units derived from (meth)acrylic monomers in the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit, is preferably 2% by mass or more, more preferably 4% by mass or more, even more preferably 6% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0020] The total content of styrene compounds and (meth)acrylic monomers in the raw material monomer (a) constituting the styrene-acrylic resin (A), or the total content of constituent units derived from styrene compounds and constituent units derived from (meth)acrylic monomers in the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit, is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 99% by mass or more, and 100% by mass or less, even more preferably 100% by mass, from the viewpoint of improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability.

[0021] (Manufacturing of resin (A)) In the present invention, the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit is preferably polymerized in the absence of the polyester resin (B) constituting the polyester resin unit, using a polymerization system separate from the polymerization system of the raw material monomer (b) constituting the polyester resin (B), from the viewpoint of controlling the molecular weight, molecular weight distribution, and copolymerizability of the monomer, and improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. From the above viewpoint, the polymerization method of the styrene-acrylic resin (A) may be a polymerization method that can control the molecular weight, molecular weight distribution, and copolymerizability of the monomer, such as a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method, in addition to a bulk polymerization method. That is, from the above viewpoint, the binder resin of the present invention is a binder resin for toner containing a composite resin in which a styrene-acrylic resin unit and a polyester resin unit are bonded via covalent bonds, and the acid value of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit is 40 mgKOH / g or more.

[0022] From the viewpoint of ease of controlling molecular weight, molecular weight distribution, and monomer copolymerizability, the styrene-acrylic resin (A) is preferably formed by the following step I. Step I: A process to obtain styrene-acrylic resin (A) by polymerizing raw material monomer (a) in a polymerization system separate from the polymerization system for raw material monomer (b) that constitutes polyester resin (B), in the absence of polyester resin (B) that constitutes polyester resin unit.

[0023] The styrene-acrylic resin (A) is preferably formed by bulk polymerization or solution polymerization, and more preferably by bulk polymerization, from the viewpoint of ease of controlling molecular weight, molecular weight distribution, and copolymerizability of monomers. That is, the polymerization of the raw material monomer (a) in step I is preferably bulk polymerization or solution polymerization, and more preferably bulk polymerization.

[0024] In the present invention, "bulk polymerization" refers to addition polymerization carried out under conditions in which there is substantially no solvent in the reaction system, that is, under solvent-free conditions. In bulk polymerization (when the polymerization in step I is bulk polymerization), a radical generator may be used. Examples of radical generators include peroxides such as di-tert-butyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile). In bulk polymerization, the concentration of the radical generator is preferably 7% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more preferably 0% by mass, relative to the total amount of raw material monomer (a) of the styrene acrylic resin (A), when the total amount of raw material monomer (a) of the styrene acrylic resin (A) is 100% by mass. In other words, it is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 2 parts by mass or less, even more preferably 1 part by mass or less, even more preferably 0.5 parts by mass or less, and even more preferably 0 parts by mass, relative to 100 parts by mass of the total amount of raw material monomer (a), and it is preferable to carry out the process under catalyst-free conditions.

[0025] Bulk polymerization (when the polymerization in step I is bulk polymerization) is preferably carried out at a high temperature under pressure above atmospheric pressure, and more preferably as continuous bulk polymerization under high temperature and high pressure. In this invention, a pressurized state refers to a state in which the contents are heated to a temperature above the boiling point under normal pressure in a sealed container such as an autoclave. Under high pressure above atmospheric pressure and at high temperatures, radicals generated by the thermal initiation reaction of the raw material monomer (a) function as polymerization initiators. This allows addition polymerization to proceed even under conditions with relatively few radical generators, resulting in the acquisition of a styrene-acrylic resin (A) with a narrow molecular weight distribution. Furthermore, in the case of continuous bulk polymerization, the monomer composition distribution can be controlled in addition to the molecular weight distribution, making it possible to obtain a more uniform styrene-acrylic resin (A) with a narrow monomer composition distribution. This further improves low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. From the above viewpoint, the temperature of bulk polymerization is preferably 160°C or higher, more preferably 170°C or higher, even more preferably 180°C or higher, even more preferably 190°C or higher, and preferably 350°C or lower, more preferably 320°C or lower.

[0026] In this invention, "solution polymerization" refers to addition polymerization carried out under conditions in which a solvent is present in the reaction system. The resulting polymer may dissolve in the solvent or precipitate without dissolving in the solvent. In solution polymerization, it is preferable to heat the raw material monomer (a) in a solvent together with a polymerization initiator, a polymerization chain transfer agent, etc., to carry out addition polymerization. Examples of polymerization initiators include peroxides such as dibutyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile). The amount of polymerization initiator added is not particularly limited, but is preferably 0.5 parts by mass or more, and preferably 30 parts by mass or less, per 100 parts by mass of the total amount of raw material monomer (a). Examples of polymerization chain transfer agents include mercaptans such as 2-mercaptoethanol and 3-mercaptopropionic acid. The amount of polymerization chain transfer agent added is not particularly limited, but is preferably 0.01 parts by mass or more, and preferably 10 parts by mass or less, per 100 parts by mass of the total amount of raw material monomer (a). In the case of solution polymerization, after the polymerization reaction is complete, the resulting polymer may be isolated and purified from the reaction solution by known methods such as reprecipitation and solvent removal.

[0027] The acid value of the styrene-acrylic resin (A) is 40 mg KOH / g or more, preferably 43 mg KOH / g or more, more preferably 46 mg KOH / g or more, even more preferably 48 mg KOH / g or more, even more preferably 50 mg KOH / g or more, and preferably 300 mg KOH / g or less, more preferably 250 mg KOH / g or less, even more preferably 200 mg KOH / g or less, even more preferably 150 mg KOH / g or less, and even more preferably 100 mg KOH / g or less, from the viewpoint of compounding with the polyester resin (B) that constitutes the polyester resin unit, and from the viewpoint of improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability.

[0028] The weight-average molecular weight of the styrene-acrylic resin (A) is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 7,000 or more, and more preferably 200,000 or less, more preferably 100,000 or less, even more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less, and even more preferably 10,000 or less, from the viewpoint of further improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. The weight-average molecular weight of styrene-acrylic resin (A) can be adjusted by the polymerization temperature and polymerization time.

[0029] The glass transition temperature of the styrene-acrylic resin (A) is preferably 45°C or higher, more preferably 50°C or higher, and more preferably 120°C or lower, more preferably 90°C or lower, even more preferably 70°C or lower, and even more preferably 55°C or lower, from the viewpoint of further improving low-temperature fixing properties, hot offset resistance, heat storage resistance, and electrostatic stability. The softening point of the styrene-acrylic resin (A) is preferably 90°C or higher, more preferably 100°C or higher, even more preferably 105°C or higher, and preferably 160°C or lower, more preferably 140°C or lower, and even more preferably 120°C or lower, from the viewpoint of further improving low-temperature fixing properties, hot offset resistance, heat storage resistance, and electrostatic stability. In particular, the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit is more preferably a glass transition temperature of 50°C or higher and a softening point of 105°C or higher, from the viewpoint of further improving low-temperature fixing properties, hot offset resistance, heat storage resistance, and electrostatic stability. The acid value, weight-average molecular weight, glass transition temperature, and softening point of styrene-acrylic resin (A) can be measured by the method described in the examples.

[0030] [Polyester resin (B)] The polyester resin (B) constitutes the polyester resin unit of the composite resin, and is preferably a polyester resin which is a polycondensate of an alcohol component (b-al) and a carboxylic acid component (b-ac) as the raw material monomer (b). The alcohol component (b-al) and carboxylic acid component (b-ac) contained in the polyester resin will be described below.

[0031] (Alcohol content (b-al)) The alcohol component (b-al) includes aromatic diols, aliphatic diols, alicyclic diols, and polyhydric alcohols with a valency of three or higher. Examples of aromatic diols include alkylene oxide adducts of bisphenol A [2,2-bis(4-hydroxyphenyl)propane] (hereinafter also referred to as "BPA-AO"). Preferably, BPA-AO is of formula (I): [ka] [In the formula, OR 11 and R 12 O is an alkylene oxy group, R 11 and R 12A BPA-AO represented by [ ] is an alkylene group (preferably an ethylene group or a propylene group) having 1 to 4 carbon atoms, x and y are the average number of moles of alkylene oxide added, each independently being a positive number, and the average value of the sum of x and y is preferably 1 or more, more preferably 1.5 or more, even more preferably 2 or more, and preferably 16 or less, more preferably 8 or less, and even more preferably 4 or less.

[0032] Examples of BPA-AO include polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(3.3)-2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene(2.2)-2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene(2.0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2.0)-polyoxyethylene(2.0)-2,2-bis(4-hydroxyphenyl)propane, and polyoxypropylene(6)-2,2-bis(4-hydroxyphenyl)propane. The numbers in parentheses above correspond to the average value of the sum of x and y in equation (I) above.

[0033] The BPA-AO is preferably a propylene oxide adduct of bisphenol A (hereinafter also referred to as "BPA-PO") or an ethylene oxide adduct of bisphenol A (hereinafter also referred to as "BPA-EO"). One or more of these BPA-AOs may be used.

[0034] The aliphatic diol has two or more carbon atoms, preferably 18 or fewer, more preferably 14 or fewer, even more preferably 10 or fewer, and still more preferably 6 or fewer. Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0035] Examples of alicyclic diols include 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, and alkylene oxide adducts of hydrogenated bisphenol A with 2 to 4 carbon atoms (average number of added moles: 2 to 12).

[0036] Examples of polyhydric alcohols with a valency of 3 or higher include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene. Furthermore, from the viewpoint of adjusting the molecular weight and softening point of the resin, the alcohol component (b-al) may include a monohydric alcohol. These alcohol components may be used individually or in combination of two or more types.

[0037] The alcohol component (b-al) preferably comprises one or more selected from aromatic diols and aliphatic diols having 2 to 18 carbon atoms, more preferably comprising one or more selected from alkylene oxide adducts of bisphenol A, ethylene glycol, 1,2-propanediol, 1,3-propanediol, and neopentyl glycol, and even more preferably comprising alkylene oxide adducts of bisphenol A (BPA-AO).

[0038] The amount of BPA-AO is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, even more preferably 98 mol% or more, and 100 mol% or less, and even more preferably 100 mol%, relative to the alcohol component (b-al).

[0039] (Carboxylic acid component (b-ac)) Examples of carboxylic acid components (b-ac) include dicarboxylic acid compounds and polycarboxylic acid compounds with a valency of three or more.

[0040] Examples of dicarboxylic acid compounds include aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and alicyclic dicarboxylic acid compounds. The number of carbon atoms in the dicarboxylic acid compound is preferably 2 or more, more preferably 3 or more, and preferably 30 or less, more preferably 20 or less. Examples of aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, and terephthalic acid. Among these, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred. Examples of aliphatic dicarboxylic acid compounds include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, pentaneoic acid, adipic acid, sebacic acid, dodecaneoic acid, azelaic acid, and succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms. Examples of succinic acids substituted with aliphatic hydrocarbon groups having 1 to 20 carbon atoms include n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octenyl succinic acid, n-octyl succinic acid, isooctenyl succinic acid, and isooctyl succinic acid. Examples of alicyclic dicarboxylic acid compounds include cyclohexanedicarboxylic acid.

[0041] Examples of polycarboxylic acid compounds with three or more valent carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalentricarboxylic acid, and pyromellitic acid.

[0042] The carboxylic acid component (b-ac) preferably comprises one or more selected from aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and polycarboxylic acid compounds of trivalent or higher valency, more preferably comprising one or more selected from terephthalic acid, isophthalic acid, maleic acid, fumaric acid, alkenyl succinic acid, and trimellitic acid, even more preferably comprising one or more selected from terephthalic acid, isophthalic acid, fumaric acid, and trimellitic acid, and even more preferably comprising one or more aromatic dicarboxylic acid compounds selected from terephthalic acid and isophthalic acid. The amount of aromatic dicarboxylic acid compound is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, and even more preferably 100 mol%, in the carboxylic acid component (b-ac).

[0043] Furthermore, the carboxylic acid component (b-ac) may appropriately contain polycarboxylic acid compounds of trivalent or higher valentity from the viewpoint of controlling the degree of polymerization of the resin. The polycarboxylic acid compound with a valency of 3 or more may be used in an amount of preferably 0.2% to 30% by mass, and more preferably 0.5% to 20% by mass, relative to the total amount of raw material monomers (b) of the polyester resin (B).

[0044] The equivalent ratio [COOH group / OH group] of the carboxyl group (COOH group) of the carboxylic acid component (b-ac) to the hydroxyl group (OH group) of the alcohol component (b-al) is preferably 0.7 or higher, more preferably 0.8 or higher, even more preferably 0.9 or higher, even more preferably 1.0 or higher, and preferably 1.3 or lower, more preferably 1.2 or lower.

[0045] (Manufacturing of resin (B)) The resin (B) is preferably produced by a polycondensation reaction of a raw material monomer (b) containing an alcohol component (b-al) and a carboxylic acid component (b-ac), and the polycondensation reaction is more preferably carried out by the following step I' from the viewpoint of further improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. Step I': A step to obtain polyester resin (B) by polymerizing raw material monomer (b) in a polymerization system separate from the polymerization system for raw material monomer (a) that constitutes styrene acrylic resin (A), in the absence of styrene acrylic resin (A) that constitutes the styrene acrylic resin unit.

[0046] The polycondensation reaction in step I' may be carried out using, if necessary, an esterification catalyst such as di(2-ethylhexanoate)tin(II), dibutyltin oxide, or titanium diisopropylate bistriethanolamine in an amount of 0.01 parts by mass to 5 parts by mass per 100 parts by mass of the total amount of raw material monomer (b); and an esterification co-catalyst such as gallic acid (same as 3,4,5-trihydroxybenzoic acid) in an amount of 0.001 parts by mass to 0.5 parts by mass per 100 parts by mass of the total amount of raw material monomer (b). Furthermore, when using monomers having unsaturated bonds, such as fumaric acid, in the polycondensation reaction in step I', a radical polymerization inhibitor may be used, preferably in an amount of 0.001 parts by mass or more and 0.5 parts by mass or less, per 100 parts by mass of the total amount of raw material monomer (b), as needed. An example of a radical polymerization inhibitor is 4-tert-butylcatechol. The temperature of the polycondensation reaction in step I' is preferably 120°C or higher, more preferably 160°C or higher, even more preferably 180°C or higher, and preferably 260°C or lower, more preferably 240°C or lower. The polycondensation reaction may be carried out in an inert gas atmosphere.

[0047] The softening point of the polyester resin (B) is preferably 80°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. The glass transition temperature of the polyester resin (B) is preferably 50°C or higher, more preferably 55°C or higher, even more preferably 60°C or higher, and preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower. The acid value of the polyester resin (B) is preferably 2 mg KOH / g or more, more preferably 30 mg KOH / g or less, more preferably 20 mg KOH / g or less, and even more preferably 10 mg KOH / g or less. The hydroxyl value of the polyester resin (B) is preferably 20 mg KOH / g or more, more preferably 30 mg KOH / g or more, even more preferably 40 mg KOH / g or more, and preferably 80 mg KOH / g or less, more preferably 70 mg KOH / g or less, and even more preferably 60 mg KOH / g or less. The softening point, glass transition temperature, acid value, and hydroxyl value of polyester resin (B) can be measured by the method described in the examples.

[0048] [Manufacturing method for binder resin for toner] The binder resin of the present invention contains a composite resin formed by compounding a styrene-acrylic resin (A) that constitutes a styrene-acrylic resin unit and a polyester resin (B) that constitutes a polyester resin unit. The present invention provides a method for producing a binder resin that further improves low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. Step I: A step to obtain a styrene-acrylic resin (A) by polymerizing the raw material monomer (a) in a polymerization system different from the polymerization system for the raw material monomer (b) constituting the polyester resin unit, in the absence of the polyester resin (B) constituting the polyester resin unit, and, Step II: A step to obtain a toner binder resin containing the composite resin by covalently bonding the styrene-acrylic resin (A) obtained in Step I with a polyester resin (B). It is preferable to include it. The production of styrene-acrylic resin (A) in process I is as described above.

[0049] The method for producing the binder resin of the present invention preferably further includes step I' from the viewpoint of further improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. The production of polyester resin (B) in process I' is as described above. In the present invention, if step I' is included, step II is preferably a step in which the styrene-acrylic resin (A) obtained in step I and the polyester resin (B) obtained in step I' are bonded via a covalent bond formed by a polymer reaction to obtain a binder resin for toner containing the composite resin. That is, the polymer reaction in step II is preferably a condensation reaction between the styrene-acrylic resin (A) and the polyester resin (B) from the viewpoint of ensuring sufficient composite formation and further improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. As a result, the styrene-acrylic resin (A) and the polyester resin (B) are bonded and composited via a covalent ester bond. Examples of such condensation reactions include a condensation reaction between the carboxyl group of the styrene-acrylic resin (A) and the hydroxyl group of the polyester resin (B), or a condensation reaction between the hydroxyl group of the styrene-acrylic resin (A) and the carboxyl group of the polyester resin (B).

[0050] In Step II, from the viewpoint of making the composite sufficient and further improving low-temperature fixing property, hot offset resistance, heat storage stability, and charge stability, the composite of the styrene-acrylic resin (A) and the polyester resin (B) is preferably carried out by forming a covalent bond through a compound (hereinafter also referred to as "both-reactive compound") that can react with any of the raw material monomers (a) constituting the resin (A) and the raw material monomers (b) constituting the resin (B). That is, Step II is preferably a step of forming a covalent bond through a structural unit derived from the both-reactive compound contained in either the styrene-acrylic resin (A) or the polyester resin (B) to obtain a toner binder resin containing the composite resin. More preferably, it is a step of forming a covalent bond by a polymer reaction between the styrene-acrylic resin (A) and the polyester resin (B) through a structural unit derived from the both-reactive compound contained in the styrene-acrylic resin (A) to obtain a toner binder resin containing the composite resin.

[0051] The both-reactive compound is preferably a compound that can react with any of the raw material monomers of the styrene-acrylic resin (A) and the polyester resin (B), and more preferably a compound that can be composite by forming an ester bond formed by a condensation reaction between the styrene-acrylic resin (A) and the polyester resin (B). For example, those represented by the following general formulas (II-1) and (II-2) can be mentioned.

[0052] [Chemical formula] [In the formula, R 21 , R 22 and R 23 are the same or different and represent a hydrogen atom, a hydroxyl group, an alkyl group optionally having a substituent, an alkoxy group, an aryl group, a vinyl group or a halogen atom, and these may be bonded to each other to form a ring. A and B are the same or different and represent a group represented by the following general formula (III-1), general formula (III-2) or general formula (III-3). X and Y are the same or different and are -COOR 4 or -OR 5 (R 4and R 5 (This indicates a hydrogen atom or a lower alkyl group which may have a substituent.)

[0053] [ka] [In the formula, R 31 , R 32 and R 33 The terms are the same or different and represent a hydrogen atom, a hydroxyl group, an optionally substituted alkyl group, alkoxy group, aryl group, vinyl group, or halogen atom, which may be bonded to each other to form a ring. m represents a number from 0 to 5, and n represents a number from 0 to 2.

[0054] Here, it is preferable that both of these reactive compounds can react with either the raw material monomers of the styrene-acrylic resin (A) or the polyester resin (B). However, if there are two or more raw material monomers for both the styrene-acrylic resin (A) and the polyester resin (B), it is sufficient that they can react with at least one of them.

[0055] In general formulas (II-1), (II-2), and (III-1) to (III-3), R 21 ~R 23 and R 31 ~R 33 Specific examples or preferred embodiments of alkyl groups, alkoxy groups, aryl groups, vinyl groups, and halogen atoms among those indicated are as follows: The alkyl group is preferably linear or branched and has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms. Examples include methyl, ethyl, n-propyl, i-propyl, n-butyl, and tert-butyl groups. These alkyl groups may be substituted with phenyl, naphthyl, or hydroxyl groups. Examples of alkoxy groups include methoxy groups, ethoxy groups, n-propoxy groups, i-propoxy groups, and t-butoxy groups, and these groups may be substituted with hydroxyl groups, carboxyl groups, etc. Examples of aryl groups include phenyl, benzyl, and naphthyl groups, and these groups may be substituted with methyl, ethyl, methoxy, ethoxy, carboxyl, or hydroxyl groups. The vinyl group may be substituted with, for example, a hydroxyl group, a phenyl group, an alkyl group, an alkoxy group, or a carboxyl group. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms, with chlorine and bromine atoms being preferred. R 4 and R 5 The lower alkyl group represented by preferably has 1 to 4 carbon atoms, and examples include methyl groups and ethyl groups, and these groups may be substituted with hydroxyl groups or the like.

[0056] When X is a carboxyl group in general formula (II-2), examples of compounds represented by general formula (II-2) include ethylenically unsaturated monocarboxylic acid compounds represented by the following general formulas (IV-1) to (IV-3). [ka] [In the formula, R 41 and R 42 R 21 ~R 23 R represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group or vinyl group or a halogen atom, similar to the above. 43 and R 44 They are the same or different, R 21 ~R 23 This represents an alkyl group, aryl group, vinyl group, or halogen atom, which may have substituents, similar to the above. A is the same as above.

[0057] Specific examples of ethylenically unsaturated monocarboxylic acid compounds represented by general formulas (IV-1) to (IV-3) include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, and their lower alkyl esters and anhydrides.

[0058] When X and Y are carboxyl groups in general formula (II-1), examples of compounds represented by general formula (II-1) include ethylenically unsaturated dicarboxylic acid compounds represented by the following general formulas (V-1) and (V-2). [ka] [In the formula, R 51 and R 52 R 21 ~R 23 This represents a hydrogen atom, an optionally substituted alkyl group, aryl group, vinyl group, or halogen atom, similar to the above. A and B are the same as described above.

[0059] Specific examples of ethylenically unsaturated dicarboxylic acid compounds represented by general formulas (V-1) and (V-2) include maleic acid, fumaric acid, itaconic acid, mesaconic acid, citraconic acid, and their lower alkyl esters and anhydrides.

[0060] When X is a hydroxyl group in general formula (II-2), the compounds represented by general formula (II-2) are preferably ethylenically unsaturated monoalcohols represented by the following general formulas (VI-1) to (VI-3). [ka] [In the formula, R 61 ~R 64 R 21 ~R 23 It represents a hydrogen atom, an optionally substituted alkyl group, or an aryl group, similar to the above. A is the same as above.

[0061] Specific examples of ethylenic monoalcohols represented by general formulas (VI-1) to (VI-3) include 2-vinylphenol, 4-vinylphenol, 4-(1-methylethenyl)phenol, 2-allylphenol, 4-allylphenol, 2-hydroxyethyl (meth)acrylate, and 2-hydroxyethylhexyl (meth)acrylate.

[0062] When X and Y are hydroxyl groups in general formula (II-1), preferred compounds represented by general formula (II-1) include ethylenically unsaturated dialcohols represented by the following general formulas (VII-1) and (VII-2). [ka] [In the formula, R 71 and R 72 R 21 ~R 23 This represents a hydrogen atom, an optionally substituted alkyl group, aryl group, vinyl group, or halogen atom, similar to the above. A and B are the same as described above.

[0063] The two reactive compounds are preferably ethylenically unsaturated monocarboxylic acid compounds, and more preferably acrylic acid, from the viewpoint of ensuring sufficient complexation and further improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability. It is preferable to introduce both reactive compounds into the polymer backbone as raw material monomers for either the styrene-acrylic resin (A) or the polyester resin (B) before compounding, and then compound them with the other resin via the reactive compounds. From the viewpoint of ensuring sufficient compounding, it is even more preferable to introduce them into the polymer backbone as raw material monomer (a) for the styrene-acrylic resin (A) before compounding, and then compound them with the polyester resin (B) via the reactive compounds. When the raw material monomer (a) for the styrene-acrylic resin (A) contains an ethylenically unsaturated monocarboxylic acid compound as one of the reactive compounds, compounding occurs via ester bonds formed by the condensation reaction between the carboxyl group introduced into the polymer backbone by the inclusion of structural units derived from the ethylenically unsaturated monocarboxylic acid compound in the styrene-acrylic resin (A) and the hydroxyl group of the polyester resin (B).

[0064] The amount of both reactive compounds that can react with either the styrene-acrylic resin (A) or the polyester resin (B) is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, even more preferably 5% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, even more preferably 25% by mass or less, even more preferably 20% by mass or less, even more preferably 15% by mass or less, and even more preferably 10% by mass or less, based on the total amount of raw material monomer (a) of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit, with the total amount of raw material monomer (a) being 100% by mass. In other words, the amount of both reactive compounds is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and preferably 40 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the total amount of raw material monomer (a).

[0065] The mass ratio of the polyester resin (B) constituting the polyester resin unit in the composite resin to the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit [polyester resin (B) / styrene-acrylic resin (A)], or the mass ratio of the total amount of raw material monomer (b) constituting the polyester resin unit to the total amount of raw material monomer (a) constituting the styrene-acrylic resin unit [total amount of raw material monomer (b) / total amount of raw material monomer (a)], is preferably 30 / 70 to 98 / 2, more preferably 50 / 50 to 95 / 5, and even more preferably 70 / 30 to 90 / 10, from the viewpoint of improving the dispersibility of the styrene-acrylic resin unit and further improving low-temperature fixability, hot offset resistance, heat storage resistance, and electrostatic stability.

[0066] When step II is carried out by a polymer reaction, the method is not particularly limited as long as it can form a covalent bond, but a method of heating, melting, and mixing the styrene-acrylic resin (A) and the polyester resin (B) is preferred. The temperature during the polymer reaction in step II is preferably 100°C or higher, more preferably 130°C or higher, even more preferably 150°C or higher, and preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 200°C or lower. The polymer reaction in step II may be carried out under pressure or reduced pressure from the viewpoint of reactivity, but it is preferable to carry it out at atmospheric pressure from the viewpoint of ease of reaction. Furthermore, the time for the polymer reaction can be appropriately adjusted depending on the reaction temperature, etc., but is preferably 1 hour or more, preferably 24 hours or less, more preferably 12 hours or less, and even more preferably 6 hours or less.

[0067] The content of the composite resin in the binder resin of the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and 100% by mass or less, even more preferably 100% by mass or less, from the viewpoint of further improving low-temperature fixing properties, hot offset resistance, heat storage resistance, and electrostatic stability.

[0068] The softening point of the binder resin of the present invention is preferably 70°C or higher, more preferably 85°C or higher, even more preferably 100°C or higher, even more preferably 110°C or higher, and preferably 150°C or lower, more preferably 140°C or lower, even more preferably 130°C or lower, and even more preferably 120°C or lower. The glass transition temperature of the binder resin of the present invention is preferably 50°C or higher, more preferably 53°C or higher, and preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower. The acid value of the binder resin of the present invention is preferably 50 mg KOH / g or less, more preferably 40 mg KOH / g or less, even more preferably 35 mg KOH / g or less, and even more preferably 30 mg KOH / g or less. On the other hand, the acid value of the binder resin of the present invention is preferably 2 mg KOH / g or more, more preferably 8 mg KOH / g or more, even more preferably 14 mg KOH / g or more, and even more preferably 20 mg KOH / g or more. The softening point, glass transition temperature, and acid value of the binder resin of the present invention can be easily adjusted to these ranges by adjusting the type and amount of raw material monomers, the amount of radical generator, the amount of catalyst, etc., or by selecting reaction conditions.

[0069] The binder resin of the present invention may be used alone or in combination of two or more types. When two or more binder resins of the present invention are used in combination, one example is when two binder resins with different softening points are used. The difference in softening points between the binder resin with a low softening point and the resin with a high softening point is preferably 5°C or more, more preferably 7°C or more, even more preferably 10°C or more, and preferably 40°C or less, more preferably 30°C or less, and even more preferably 20°C or less. When using a binder resin with a low softening point and a binder resin with a high softening point in combination, the mixing ratio of the binder resin with the low softening point (low softening point binder resin / high softening point binder resin) is preferably 10 / 90 or more and 90 / 10 or less, more preferably 20 / 80 or more and 80 / 20 or less, and even more preferably 30 / 70 or more and 70 / 30 or less.

[0070] [Toner for developing electrostatic images] The toner of the present invention contains the binder resin. The content of the binder resin in the toner is preferably 80% by mass or more, more preferably 90% by mass or more, and 100% by mass or less. Toner, for example, contains toner particles and external additives. The toner particles preferably contain the binder resin. Furthermore, the toner particles may contain, for example, colorants, colorant derivatives, release agents such as waxes, charge control agents, magnetic materials, and other additives. Among these, the toner particles preferably contain colorants.

[0071] <Coloring agent> The coloring agent may be either a pigment or a dye. Examples of colorants include various types of carbon black produced by methods such as the thermal black method, acetylene black method, channel black method, and lamp black method; grafted carbon black, in which the surface of carbon black is coated with resin; nigrosine dyes; phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, pigment blue 15:3, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, and mixtures thereof. From the viewpoint of improving the image density of the toner, the amount of colorant is preferably 1 to 15 parts by mass, and more preferably 2 to 10 parts by mass, per 100 parts by mass of the binder resin.

[0072] <Charge control agent> The toner of the present invention may contain a charge control agent. The charge control agent may contain either a positively charged charge control agent or a negatively charged charge control agent. These charge control agents may be used individually or in combination of two or more types.

[0073] Examples of positively charged charge control agents include nigrosine dyes, triphenylmethane-based dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and styrene-acrylic resins. Examples of nigrosine dyes include "Nigrosine Base EX," "Oil Black BS," "Oil Black SO," "Bontron N-01," "Bontron N-07," and "Bontron N-11" (all manufactured by Orient Chemical Industry Co., Ltd.). Examples of quaternary ammonium salt compounds include "Bontron P-51" (manufactured by Orient Chemical Industry Co., Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX VP435" (manufactured by Hoechst). An example of a polyamine resin is "AFP-B" (manufactured by Orient Chemical Industry Co., Ltd.). Examples of imidazole derivatives include "PLZ-2001" and "PLZ-8001" (both manufactured by Shikoku Chemicals, Inc.). An example of a styrene-acrylic resin is "FCA-701PT" (manufactured by Fujikura Chemicals, Inc.). In particular, Bontron N-07 can be used.

[0074] Specific examples of negatively charged charge control agents include, for example, metal-containing azo dyes, metal compounds of benzyl acid compounds, metal compounds of salicylic acid compounds, copper phthalocyanine dyes, quaternary ammonium salts, nitroimidazole derivatives, and organometallic compounds. Examples of metal-containing azo dyes include "Barifast Black 3804" and "Bontron S-31" (both manufactured by Orient Chemical Co., Ltd.), "T-77" (manufactured by Hodogaya Chemical Co., Ltd.), "Bontron S-32", "Bontron S-34", and "Bontron S-36" (all manufactured by Orient Chemical Co., Ltd.), and "Eisenspiron Black TRH" (manufactured by Hodogaya Chemical Co., Ltd.). Examples of metal compounds of salicylic acid compounds include "Bontron E-81", "Bontron E-82", "Bontron E-84", and "Bontron E-85" (all manufactured by Orient Chemical Co., Ltd.). An example of a quaternary ammonium salt is "COPY CHARGE NX VP434" (manufactured by Hoechst). An example of an organometallic compound is "TN105" (manufactured by Hodogaya Chemical Co., Ltd.). In particular, Bontron E-81, Bontron S-34, T-77, and Eisenspiron Black TRH can be used.

[0075] The charge control agent content is preferably 0.1 parts by mass to 8 parts by mass, and more preferably 0.2 parts by mass to 5 parts by mass, per 100 parts by mass of the binder resin.

[0076] <wax> The toner of the present invention preferably contains a wax such as polyolefin or paraffin wax as an offset prevention agent. The wax content is preferably 1 to 5 parts by mass per 100 parts by mass of the binder resin. Examples of polyolefins include polyethylene and polypropylene, and those with relatively low molecular weights, particularly those with a molecular weight of 3,000 to 15,000 as determined by vapor permeation, are preferred. Furthermore, those with a softening point of 70°C to 150°C as determined by the ring-ball method, particularly 120°C to 150°C, are preferred.

[0077] <Other additives> The toner particles may also contain, as appropriate, other additives such as magnetic powder, fluidity enhancers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, anti-aging agents, and cleaning performance enhancers.

[0078] In the toner of the present invention, the toner particle content 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, preferably 99% by mass or less.

[0079] Volume-intermediate particle size of toner particles (D 50 The volume median particle size (D) is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. In this specification, the volume median particle size (D) 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.

[0080] <External additives> The toner of the present invention may contain, for example, toner particles and an external additive, by treating the surface of the toner particles with a property improver such as an external additive in order to improve fluidity. Examples of external additives include fine particles of inorganic materials such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles. One or more of these may be used. Among these external additives, silica is preferred, and hydrophobic silica treated with a hydrophobic treatment agent is more preferred.

[0081] Examples of hydrophobic treatment agents include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), and methyltriethoxysilane. Among these, hexamethyldisilazane is preferred.

[0082] When surface treatment of toner particles is performed using an external additive, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.08 parts by mass or more, even more preferably 0.1 parts by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, from the viewpoint of the chargeability and fluidity of the toner.

[0083] [Toner manufacturing method] The toner of the present invention may be obtained by any known method such as melt-kneading, emulsion-phase inversion, suspension polymerization, or emulsion-coagulation, but from the viewpoint of productivity and dispersibility of colorants, pulverized toner obtained by melt-kneading is preferred. In the melt-kneading method, the binder resin, colorant, and optionally property improver are uniformly dispersed, and then the mixture is melt-kneaded, cooled, crushed, and classified by a known method, resulting in a medium volume particle size (D 50 ) Toner with a thickness of 5 μm or more and 15 μm or less can be obtained.

[0084] The toner of the present invention is used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like. The toner can be used as a non-magnetic one-component developer, or as a dry two-component developer by mixing it with carriers such as iron oxide carriers, spherical iron oxide carriers, and ferrite carriers, either as is or coated with resin or the like. [Examples]

[0085] [measurement] [Acid value and hydroxyl value of resins] The acid value and hydroxyl value of the resin were measured according to the method of JIS K0070:1992. However, in this method, the measurement solvent was changed from a mixed solvent of ethanol and ether to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for measuring the acid value, and to tetrahydrofuran for measuring the hydroxyl value.

[0086] [Weight-average molecular weight of resins] The molecular weight distribution was measured by gel permeation chromatography (GPC), obtained using the following method, and the weight-average molecular weight was determined. (1) Preparation of sample solution The sample was dissolved in tetrahydrofuran to a concentration of 0.5 g / 100 mL. This solution was then filtered using a 2 μm pore size fluororesin filter "FP-200" (manufactured by Sumitomo Electric Industries, Ltd.) to remove insoluble components and obtain the sample solution. (2) Measurement of weight-average molecular weight Using the measurement apparatus and analytical column described below, tetrahydrofuran was flowed as the eluent at a flow rate of 1 mL / min, and the column was stabilized in a constant temperature bath at 40°C. 100 μL of the sample solution was injected into the column and measurements were performed. The molecular weight of the sample was calculated based on a pre-prepared calibration curve. The calibration curve used in this case included several types of monodisperse polystyrene (Tosoh Corporation's "A-500" (Mw: 5.0 × 10)). 2 ), "A-1000" (Mw: 1.01 × 10 3 ), "A-2500" (Mw: 2.63 × 10 3 ), "A-5000" (Mw: 5.97 × 103 ), "F-1" (Mw: 1.02 × 10 4 ), "F-2" (Mw: 1.81 × 10 4 ), "F-4" (Mw: 3.97×10 4 ), "F-10" (Mw: 9.64×10 4 ), "F-20" (Mw: 1.90×10 5 ), "F-40" (Mw: 4.27×10 5 ), "F-80" (Mw: 7.06×10 5 ), "F-128" (Mw: 1.09 × 10 6 The sample prepared using )) as a standard sample is used. The value in parentheses indicates the molecular weight. Measuring device: "HLC-8220GPC" (manufactured by Tosoh Corporation) Analysis columns: "GMHXL" + "G3000HXL" (manufactured by Tosoh Corporation)

[0087] [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 was weighed into an aluminum pan, heated to 200°C, and then cooled to 0°C at a rate of 10°C / min. Next, the temperature was increased to 150°C at a rate of 10°C / min, and the temperature at the intersection of the extension of the baseline below the highest endothermic peak temperature and the tangent line showing the maximum slope from the rise of the peak to the peak apex was defined as the glass transition temperature.

[0088] [Softening point of resin] Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), 1 g of sample was heated at a heating rate of 6°C / min while a load of 1.96 MPa was applied by a plunger and 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 was plotted against temperature, and the temperature at which half of the sample flowed out was defined as the softening point.

[0089] [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 was 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 was heated again at a rate of 10°C / min, and the amount of heat was measured. The maximum peak temperature of the obtained endothermic reaction was defined as the melting point.

[0090] [Toner particle volume median particle size (D 50 )〕 Volume-intermediate particle size of toner particles (D 50 The following measurements were taken: • Measuring device: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Coulter Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Dispersion: "Emulgen (registered trademark) 109P" [polyoxyethylene lauryl ether, manufactured by Kao Corporation, HLB (Hydrophile-Lipophile Balance, Griffin method) = 13.6] was dissolved in the electrolyte to obtain a dispersion with a concentration of 5% by mass. • Dispersion conditions: 10 mg of the sample was added to 5 mL of the dispersion, dispersed for 1 minute using an ultrasonic disperser, then 25 mL of electrolyte was added, and dispersed again for 1 minute using an ultrasonic disperser to prepare the sample dispersion. • Measurement conditions: In a beaker, the sample dispersion is added to 100 mL of the electrolyte to adjust the concentration to a level that allows for the measurement of 30,000 particle sizes in 20 seconds. Then, the 30,000 particles are measured, and the median particle size (D) is determined from the obtained particle size distribution. 50 ) was sought.

[0091] [Manufacturing of resin (A) and resin (B)] Manufacturing examples A1-A5, comparative manufacturing example A51 (manufacturing of resins A-1-A-5 and A-51) The raw material monomers for styrene-acrylic resins, including acrylic acid as the two reactive compounds shown in Table 1, were placed in an autoclave equipped with a stainless steel stirring rod, and polymerized under pressurized heating conditions (300°C) for 2 hours. By returning to atmospheric pressure and room temperature, the precipitated styrene-acrylic resin was recovered to obtain styrene-acrylic resins A-1 to A-5 and A-51.

[0092] Manufacturing example A6 (Manufacturing of manufacturing A-6) As shown in Table 1, the raw material monomers for styrene-acrylic resin containing acrylic acid and a radical generator were placed in a stainless steel reaction vessel equipped with a thermometer, stainless steel stirring rod, a dewatering tube, a drop-flow condenser, and a nitrogen inlet tube, and the raw material monomers were polymerized at 150°C for 2 hours. Styrene-acrylic resin A-6 was obtained by recovering the precipitated styrene-acrylic resin after returning to room temperature.

[0093] [Table 1]

[0094] Manufacturing Examples B1-B4 (Manufacturing of resins B-1-B-4) 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 thermometer, stainless steel stirring rod, a drop-flow condenser with a dehydration tube, and a nitrogen inlet tube. After heating to 180°C in a nitrogen atmosphere, the temperature was increased by 5°C every hour up to 230°C to confirm that all solid monomers had melted, and then the pressure was reduced to 60 torr for 1 hour to allow dehydration condensation. After that, the pressure was returned to atmospheric pressure, cooled to 160°C, then heated to 220°C, and the reaction was maintained at 220°C for another hour. Finally, the condensation reaction was carried out under conditions of 220°C and 60 torr until the softening point shown in Table 2 was reached, yielding resins B-1 to B-4.

[0095] [Table 2]

[0096] [Manufacturing of binding resins] Examples 1-1 to 1-11 and Comparative Example 1-1 (Production of binder resins C-1 to C-11, C-51) The styrene-acrylic resin (A) and polyester resin (B) combinations and mixing ratios shown in Table 3 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-flow condenser with a dewatering tube, and a nitrogen inlet tube. The mixture was heated at 180°C for 4 hours under a nitrogen atmosphere to melt and mix the styrene-acrylic resin (A) and polyester resin (B) and induce a condensation reaction. The temperature was then further increased to 230°C and the reaction was continued for 1 hour, after which the pressure was reduced to 60 torr. After confirming that the resin's softening point reached the predetermined softening point shown in Table 3, the reaction was stopped to form a composite resin, yielding binder resins C-1 to C-11 and C-51.

[0097] [Table 3]

[0098] Comparative Example 1-2 (Manufacturing of Binding Resin C-52) The raw material monomers for the polyester resin units (excluding trimellitic anhydride shown in Table 4), acrylic acid (both reactive compounds), and the esterification catalyst and co-catalyst were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a dehydration tube, a drop-flow condenser, and a nitrogen inlet tube, and heated to 160°C under a nitrogen atmosphere. A mixed solution of the raw material monomers and polymerization initiator for the styrene-acrylic resin units shown in Table 4 was added dropwise over 1 hour. After addition, the temperature was raised to 200°C and allowed to mature for 1 hour to generate styrene-acrylic resin in the reaction system. Subsequently, the temperature was raised to 230°C every hour to confirm that all solid monomers had melted. Then, the pressure was reduced to 60 torr and dehydration condensation was carried out for 1 hour. After that, trimellitic anhydride was added, and the dehydration condensation reaction was continued at 230°C until the softening point shown in Table 4 was reached, yielding the binder resin C-52.

[0099] [Table 4]

[0100] [Toner manufacturing] Examples 2-1 to 2-11 and Comparative Examples 2-1 to 2-2 A total of 100 parts by mass of the binder resins shown in Table 5, 1 part by mass of the negative charge control agent "Bontron E-81" (manufactured by Orient Chemical Industry Co., Ltd.), 5 parts by mass of the coloring agent "Pigment blue 15:3" (manufactured by Dainichi Seika Kogyo Co., Ltd.), and 2 parts by mass of the release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80℃) were thoroughly mixed in a Henschel mixer. Then, using a twin-screw extruder with a total length of 1560 mm in the mixing section, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm, the mixture was melt-kneaded at a screw rotation speed of 200 r / min and a barrel setting temperature of 100℃. The feed rate of the mixture was 20 kg / h, and the average residence time was approximately 18 seconds. The obtained molten mixture was cooled and coarsely ground, then ground in a jet mill and classified to obtain the medium particle size (D 50 ) yielded toner particles with a diameter of 8 μm.

[0101] To 100 parts by mass of the obtained toner particles, 2.0 parts by mass of the external additive "Aerosil R-972" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., average particle size: 16 nm) was added, and the mixture was heated in a Henschel mixer at 3600 r / min for 5 minutes to obtain the toner.

[0102] [Toner Evaluation] [Low-temperature fixing properties and resistance to hot offsetting] A modified fuser unit of the "AR-505" copier (manufactured by Sharp Corporation) was modified to allow for fixing outside the unit. Each toner was mounted on this modified unit, and a printout was obtained in an unfixed state (print area: 2cm x 12cm, adhesion amount: 0.5mg / cm²). 2Subsequently, using a fuser (fixing speed 300 mm / sec) adjusted to a total fixing pressure of 40 kgf, fixing tests were performed on unfixed printed materials at each temperature while sequentially increasing the temperature of the fixing roll from 80°C to 240°C in 5°C increments. Cellophane adhesive tape "UNICEF Cellophane" (manufactured by Mitsubishi Pencil Co., Ltd., width: 18 mm, JIS Z1522) was attached to the image portion of the obtained printed material, and after passing it through a fixing roller set to 30°C, the tape was peeled off. The optical reflectance density before and after tape application was measured using a reflectance densitometer "RD-915" (manufactured by Gretag Macbeth Co., Ltd.), and the fixing roller temperature at which the ratio of the two (after peeling / before application × 100) first exceeded 90% was defined as the minimum fixing temperature. The lower the minimum fixing temperature, the better the low-temperature fixing performance. Furthermore, the hot offset temperature was determined by visually inspecting the fixed images obtained above and identifying the lowest temperature of the fuser roll at which hot offset was observed. The fuser paper used was "CopyBond SF-70NA" (manufactured by Sharp Corporation, 75g / m²). 2 ) was used. The higher the hot offset temperature, the better the resistance to hot offset. These results are shown in Table 5.

[0103] [Heat-resistant storage stability] Each toner sample (5g) was placed in a 50mL poly bottle and left for 48 hours at a temperature of 50°C and a relative humidity of 60%. The toner was then sieved through a 100μm mesh, and the remaining toner on the mesh was weighed. The heat resistance was then evaluated according to the following criteria. The results are shown in Table 5. (Evaluation Criteria) A: Remaining toner is less than 0.5g B: Remaining toner is between 0.5g and less than 1g C: Remaining toner is 1g or more

[0104] [Charge stability] Under conditions of 32°C and 50% relative humidity, 0.6g of each toner and 19.4g of silicone ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd., average particle size 90μm) were placed in a 50mL poly bottle and mixed at 250 r / min using a ball mill. The charge level of the toner was then measured using a Q / M meter (manufactured by EPPING) by the following method. After a predetermined mixing time, a specified amount of toner and carrier mixture was placed in the cell attached to the Q / M meter, and only the toner was drawn in for 90 seconds through a 32 μm mesh sieve (stainless steel, twill weave, wire diameter: 0.0035 mm). The voltage change on the carrier that occurred at that time was monitored, and the value X = [total electric charge after 90 seconds (μC) / amount of toner drawn in (g)] was defined as the charge amount (μC / g). Charge amount X after 60 seconds of mixing time 60 The amount of charge X after a mixing time of 600 seconds 600 Ratio to (X 60 / X 600 The charge stability was calculated and evaluated according to the following evaluation criteria. A higher value indicates better charge stability under high temperature and high humidity conditions. The results are shown in Table 5. (Evaluation Criteria) A: Ratio(X 60 / X 600 ) is 0.90 or higher B: Ratio (X 60 / X 600 ) is 0.80 or higher and less than 0.90 C: Ratio(X 60 / X 600 ) is less than 0.80

[0105] [Table 5]

[0106] As shown in Table 5, the toners in the examples using a binder resin containing a specific composite resin exhibit superior low-temperature fixing properties and hot-offset resistance compared to the toners in the comparative examples, due to their lower minimum fixing temperature and higher hot-offset temperature. They also demonstrate superior heat-resistant storage and electrostatic stability.

Claims

1. A method for producing a binder resin for toner, comprising a composite resin in which a styrene-acrylic resin unit and a polyester resin unit are bonded together via covalent bonds, Step I: In the absence of the polyester resin (B) that constitutes the polyester resin unit, polymerize the raw material monomer (a) in a polymerization system separate from the polymerization system for the raw material monomer (b) that constitutes the polyester resin (B) to obtain a styrene-acrylic resin (A). Step I': A step to obtain a polyester resin (B) by polymerizing the raw material monomer (b) in a polymerization system separate from the polymerization system for the raw material monomer (a) constituting the styrene-acrylic resin unit, in the absence of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit, and, Step II: A step of obtaining a toner binder resin containing the composite resin by covalently bonding the styrene-acrylic resin (A) obtained in Step I with a polyester resin (B). Includes, A method for producing a binder resin for toner, wherein the acid value of the styrene-acrylic resin (A) is 40 mg KOH / g or more.

2. The method for producing a toner binder resin according to claim 1, wherein step II is a step of bonding a styrene-acrylic resin (A) obtained in step I and a polyester resin (B) obtained in step I' via a covalent bond formed by a condensation reaction, thereby obtaining a toner binder resin containing the composite resin.

3. The method for producing a binder resin for toner according to claim 1 or 2, wherein the polymerization of the raw material monomer (a) in step I is bulk polymerization.

4. The method for producing a binder resin for toner according to Claim 3, wherein the concentration of the radical generator in the bulk polymerization of the raw material monomer (a) in step I is 1% by mass or less relative to the total amount of raw material monomer (a) of the styrene acrylic resin (A).

5. The method for producing a binder resin for toner according to claim 3 or 4, wherein the bulk polymerization of the raw material monomer (a) in step I is performed under solvent-free conditions.

6. A method for producing a binder resin for toner according to any one of claims 3 to 5, wherein the bulk polymerization of the raw material monomer (a) in step I is polymerization under catalyst-free conditions.

7. A method for producing a binder resin for toner according to any one of claims 3 to 6, wherein the bulk polymerization of the raw material monomer (a) in step I is performed under conditions of 160°C or higher.

8. A method for producing a binder resin for toner according to any one of claims 1 to 7, wherein the styrene-acrylic resin (A) has a glass transition temperature of 50°C or higher and a softening point of 105°C or higher.

9. A method for producing electrostatic image developing toner, comprising a toner binder resin produced by the method for producing toner binder resin according to any one of claims 1 to 8.

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