Binder resin for toners

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] The present invention relates to a binder resin used in a toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like. [Background technology]

[0002] In recent years, in the field of electrophotography, with the development of electrophotographic systems, there has been a demand for the development of toners for developing electrostatic images that are compatible with higher image quality and faster printing. In response to such demands, polyester resins have been proposed as binder resins for toners that have excellent low-temperature fixability. Generally, the minimum fixing temperature is in the temperature range from the low-temperature offset occurrence temperature to the high-temperature offset occurrence temperature, and therefore the usable temperature range of a binder resin is the temperature range from the minimum fixing temperature to the high-temperature offset occurrence temperature. Therefore, 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 widened, thereby satisfying the demands for energy saving and high-speed fixing. Therefore, there is a high demand for binder resins for toners and toners that are excellent in low-temperature fixing property and offset resistance. However, although polyester resins have excellent low-temperature fixing properties, they have the problem of being prone to offset.

[0003] In light of this situation, Patent Document 1 describes a toner in which the binder resin of the toner particles contains, as a low-softening point resin, a resin obtained by addition-polymerizing a vinyl monomer in the presence of a condensation polymerization monomer and, after completion of the addition polymerization reaction, condensing the condensation polymerization monomer, or a resin obtained by condensing a condensation polymerization 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 a vinyl monomer to the condensation polymerization resin obtained by condensing a condensation polymerization monomer, mixing the resulting mixture, and subjecting the mixture to addition polymerization, wherein the softening point of the low-softening point resin is 5°C or more lower than the softening point of the high-softening point resin, and the mass ratio of the low-softening point resin to the high-softening point resin is within a predetermined range, and it is disclosed that a toner having excellent low-temperature fixing properties, high-temperature offset resistance, and developability can be obtained. Patent Document 2 discloses a toner having toner particles containing a binder resin and a colorant, in which 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 a raw material thereof is chemically bonded to a polyester unit, thereby providing a toner with excellent low-temperature fixing properties, storage stability, and control of toner fusion to a photosensitive drum. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-102396 [Patent Document 2] Japanese Patent Application Publication No. 2018-10124 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the toner disclosed in Patent Document 1 uses a vinyl resin obtained by addition polymerization of a vinyl monomer in the presence of a polycondensation monomer or a polycondensation resin, and therefore has problems with controlling the molecular weight and molecular weight distribution and with monomer copolymerizability. Furthermore, in the toner disclosed in Patent Document 2, the vinyl polymer constituting the hybrid resin has a low acid value, which results in insufficient hybridization, and there are problems with heat-resistant storage stability, charging stability, and the like. The present invention relates to a binder resin for toner, a toner for developing electrostatic images, and a method for producing the binder resin for toner, which are excellent in low-temperature fixing property, hot offset resistance, heat-resistant storage stability, and charge stability. [Means for solving the problem]

[0006] The present inventors have noticed that in a binder resin for toner containing a composite resin in which a polyester resin unit excellent in low-temperature fixing property and a styrene acrylic resin unit excellent in charge property and hot offset resistance are bonded via a covalent bond, 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 making it have an acid value of a predetermined value or more, it is possible to sufficiently compound the polyester resin unit, and have found that this can solve the problems of low-temperature fixing property, hot offset resistance, heat-resistant storage stability, and charge stability.

[0007] That is, 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 via a covalent bond, The binder resin for toner, wherein the styrene acrylic resin (A) constituting the styrene acrylic resin unit has an acid value of 40 mgKOH / g or more. [2] A toner for developing electrostatic images, comprising the binder resin for toner according to [1] above. [3] A method for producing a binder resin for toner containing a composite resin in which a styrene-acrylic resin unit and a polyester resin unit are bonded via a covalent bond, comprising: Step I: A step of obtaining a styrene-acrylic resin (A) by polymerizing a raw material monomer (a) in a polymerization system independent of a polymerization system of a raw material monomer (b) constituting the polyester-based resin unit in the absence of a polyester-based resin (B) constituting the polyester-based resin unit; and Step II: A step of bonding the styrene-acrylic resin (A) obtained in Step I and the polyester resin (B) via a covalent bond to obtain a binder resin for toner containing the composite resin; Including, The method for producing a binder resin for toner, wherein the styrene-acrylic resin (A) has an acid value of 40 mgKOH / g or more. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a binder resin for toner, a toner for developing electrostatic images, and a method for producing a binder resin for toner, which are excellent in low-temperature fixing property, hot offset resistance, heat-resistant storage stability, and charge stability. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Binder resin for toner] The binder resin for toner of the present invention (hereinafter also referred to as "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 a covalent bond. The styrene acrylic resin (A) constituting the styrene acrylic resin unit has an acid value of 40 mgKOH / g or more. The toner of the present invention exhibits low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charge stability.

[0010] The reason why the present invention is effective is not clear, but 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 constituting the polyester resin unit or the raw material monomers constituting the polyester resin. Therefore, unlike conventional methods, the raw material monomers of the styrene-acrylic resin are not polymerized in a polyester resin or polycondensation monomer. This allows the inherent polymerization properties of the raw material monomers of the styrene-acrylic resin to be exerted, resulting in the formation of a more uniform styrene-acrylic resin unit with controlled molecular weight, molecular weight distribution, and copolymerizability of the monomers. Furthermore, by adjusting the acid value of the styrene-acrylic resin constituting the styrene-acrylic resin unit of the composite resin to 40 mgKOH / g or more, sufficient hybridization with the polyester resin constituting the polyester resin unit can be achieved. These synergistic effects facilitate the control of molecular motion at low temperatures and polymer chain entanglement at high temperatures, resulting in a resin with low viscosity at low temperatures and high elasticity at high temperatures, i.e., a resin that is inhibited from increasing in viscosity at low temperatures and decreasing in elasticity at high temperatures. This is believed to improve low-temperature fixability, offset resistance, heat-resistant storage stability, and charge stability.

[0011] The definitions of various terms used in this specification are shown below. The "polyester resin" may include a polyester resin that has been modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include urethane-modified polyester resins in which polyester resins are modified with urethane bonds, and epoxy-modified polyester resins in which polyester resins are modified with epoxy bonds. "Bisphenol A" means 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. The number of carbon atoms in the alkyl group of the alkyl ester is not included in the number of carbon atoms in the carboxylic acid compound. The term "binder resin" refers to a binder resin component containing a composite resin in a toner.

[0012] The toner of the present invention contains a colorant 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. The toner particles may also contain additives such as release agents, colorant derivatives, charge control agents, and other additives.

[0013] <Composite resin> The composite resin is a resin in which a styrene-acrylic resin unit and a polyester resin unit are bonded via a covalent bond. The acid value of the styrene acrylic resin (A) constituting the styrene acrylic resin unit is 40 mgKOH / g or more from the viewpoint of improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability. The method of combining the styrene acrylic resin unit and the polyester resin unit by forming a bond via a covalent bond can be exemplified by method (i) of 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 method (ii) of 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 the molecular weight, molecular weight distribution, and copolymerizability of the monomers and improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability. Among these, the method (i) using the polymer reaction described above is preferred from the viewpoint of controlling the molecular weight, molecular weight distribution, and copolymerizability of the monomers and improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability. In the case of method (i), since the composite formation method is a polymerization reaction method, it is preferable that the polymerization reactions of the styrene-acrylic resin (A) and the polyester-based resin (B) are carried out in independent reaction systems. The polymerization system of the styrene-acrylic resin (A) is preferably an addition polymerization type, and the polymerization system of the polyester-based resin (B) is preferably a polycondensation type. Independent reaction systems mean that the addition polymerization of the styrene-acrylic resin (A) and the polycondensation of the polyester-based resin (B) are carried out in separate reaction fields. In other words, the addition polymerization of the styrene-acrylic resin (A) is carried out in the absence of the polyester-based resin (B) and the raw material monomer (b) of the polyester-based resin (B), and the polycondensation of the polyester-based 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). As long as the above-mentioned polymerization reactions are independent reaction systems, the progress and completion of the two polymerization reactions do not need to be simultaneous in time, and the reactions may be progressed and completed by appropriately selecting the reaction temperature and time according to the respective reaction mechanisms. In the polymer reaction of method (i), the method for mixing the styrene acrylic resin (A) and the polyester resin (B) is not particularly limited. For example, the polyester resin (B) may be isolated and then mixed with the styrene acrylic resin (A). Alternatively, the polyester resin (B) may not be isolated, but the styrene acrylic resin (A) may be added and mixed therewith.

[0014] [Styrene acrylic resin (A)] (raw material monomer (a)) The styrene-acrylic resin (A) constitutes a styrene-acrylic resin unit of the composite resin from the viewpoint of improving low-temperature fixing property, hot offset resistance, heat-resistant storage stability, and charging stability, and is an addition polymer of raw material monomer (a) containing a styrene-based compound and a (meth)acrylic monomer.

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

[0016] Examples of the (meth)acrylic monomer include (meth)acrylic acid and (meth)acrylic acid derivatives such as 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, and methyl α-chloroacrylate. The term "(meth)acrylic acid ester" includes both acrylic acid ester and methacrylic acid ester. Of these, acrylic acid and methacrylic acid are preferred, and acrylic acid is more preferred.

[0017] The raw material monomer (a) may contain other monomers in addition to the styrene compound and the (meth)acrylic monomer. Examples of other monomers include 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 contains 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 the styrene compound in the raw material monomer (a) constituting the styrene acrylic resin (A) or the content of the structural unit derived from a styrene compound in the styrene acrylic resin (A) constituting the styrene acrylic resin unit is, from the viewpoint of improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability, 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, even more preferably 94% by mass or less. The content of the (meth)acrylic monomer in the raw material monomer (a) constituting the styrene acrylic resin (A) or the content of the structural unit derived from the (meth)acrylic monomer in the styrene acrylic resin (A) constituting the styrene acrylic resin unit is, from the viewpoint of improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability, preferably 2% by mass or more, more preferably 4% by mass or more, even more preferably 6% by mass or more, and is 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 the styrene compound and the (meth)acrylic monomer in the raw material monomer (a) constituting the styrene acrylic resin (A), or the total content of the structural units derived from the styrene compound and the structural units derived from the (meth)acrylic monomer 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 is 100% by mass or less, even more preferably 100% by mass, from the viewpoint of improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability.

[0021] (Production of Resin (A)) In the present invention, the styrene acrylic resin (A) constituting the styrene acrylic resin unit is preferably polymerized in an independent polymerization system separate from the polymerization system of the raw material monomer (b) constituting the polyester resin (B) in the absence of the polyester resin (B) constituting the polyester resin unit, from the viewpoint of controlling the molecular weight, molecular weight distribution, and copolymerizability of the monomers, and improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charge stability. From this viewpoint, the polymerization method for the styrene acrylic resin (A) may be bulk polymerization or any other polymerization method capable of controlling the molecular weight, molecular weight distribution, and copolymerizability of the monomers, such as solution polymerization, suspension polymerization, or emulsion polymerization. That is, from this viewpoint, 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 via a covalent bond, and the polymerization method for the styrene acrylic resin (A) constituting the styrene acrylic resin unit is not particularly limited as long as the toner binder resin contains the composite resin having the acid value of 40 mgKOH / g or more.

[0022] From the viewpoint of ease of control of the molecular weight, molecular weight distribution, and copolymerizability of the monomers, the styrene acrylic resin (A) is preferably formed by the following step I. Step I: A step of obtaining a styrene-acrylic resin (A) by polymerizing a raw material monomer (a) in an independent polymerization system separate from the polymerization system of a raw material monomer (b) constituting the polyester-based resin (B) in the absence of a polyester-based resin (B) constituting a polyester-based resin unit.

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

[0024] In the present invention, "bulk polymerization" refers to addition polymerization carried out under conditions where substantially no solvent is present in the reaction system, i.e., under solvent-free conditions. In bulk polymerization (when the polymerization in step I is bulk polymerization), a radical generator may be used. Examples of the radical generator include peroxides such as di-tert-butyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile). From the viewpoint of controlling the molecular weight, molecular weight distribution, and copolymerizability and further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability, the concentration of the radical generator in the bulk polymerization 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 monomers (a) of the styrene acrylic resin (A), where the total amount of the raw material monomers (a) is taken as 100% by mass. In other words, the concentration 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 monomers (a), that is, it is preferable to carry out the bulk polymerization under catalyst-free conditions.

[0025] Bulk polymerization (when the polymerization in step I is bulk polymerization) is preferably carried out at high temperature under pressure equal to or higher than atmospheric pressure, and continuous bulk polymerization at high temperature and high pressure is more preferred. In the present invention, the pressurized state refers to a state in which the contents of a sealed container such as an autoclave are heated to a temperature equal to or higher than the boiling point under normal pressure. Under high temperature and pressure equal to or higher than atmospheric pressure, radicals generated by the thermal initiation reaction of the raw material monomer (a) function as a polymerization initiator, allowing addition polymerization to proceed even under conditions in which the amount of radical generator is relatively small, and a styrene-acrylic resin (A) with a narrow molecular weight distribution can be obtained. Furthermore, when continuous bulk polymerization is used, it is possible to control not only the molecular weight distribution but also the monomer composition distribution, and a more uniform styrene-acrylic resin (A) having a narrower monomer composition distribution can be obtained, thereby further improving the low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability. From the above viewpoints, the temperature of the bulk polymerization is preferably 160°C or higher, more preferably 170°C or higher, even more preferably 180°C or higher, and even more preferably 190°C or higher, and is preferably 350°C or lower, more preferably 320°C or lower.

[0026] In the present invention, "solution polymerization" refers to addition polymerization carried out under conditions in which a solvent is present in the reaction system. The polymer produced may be dissolved in the solvent, or may precipitate without dissolving in the solvent. In solution polymerization, the raw material monomer (a) is preferably subjected to addition polymerization by heating together with a polymerization initiator, a polymerization chain transfer agent, etc. in a solvent. Examples of the polymerization initiator 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 the polymerization initiator to be added is not particularly limited, but is preferably 0.5 parts by mass or more and preferably 30 parts by mass or less relative to 100 parts by mass of the total amount of the raw material monomer (a). Examples of the polymerization chain transfer agent include mercaptans such as 2-mercaptoethanol and 3-mercaptopropionic acid. The amount of the polymerization chain transfer agent to be added is not particularly limited, but is preferably 0.01 parts by mass or more and preferably 10 parts by mass or less, based on 100 parts by mass of the total amount of the raw material monomer (a). In the case of solution polymerization, after the completion of the polymerization reaction, the produced polymer may be isolated and purified by a known method such as reprecipitation from the reaction solution or distillation of the solvent.

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

[0028] From the viewpoint of further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability, the weight-average molecular weight of the styrene-acrylic resin (A) is preferably 3,000 or more, more preferably 5,000 or more, and even more preferably 7,000 or more, and is 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. The weight average molecular weight of the styrene acrylic resin (A) can be adjusted by the polymerization temperature and polymerization time.

[0029] From the viewpoint of further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability, the glass transition temperature of the styrene-acrylic resin (A) is preferably 45°C or higher, more preferably 50°C or higher, and is 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 fixability, hot offset resistance, heat-resistant storage stability, and charge 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 is preferably 160° C. or lower, more preferably 140° C. or lower, and even more preferably 120° C. or lower. Among these, from the viewpoint of further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charge stability, it is more preferable that the styrene acrylic resin (A) constituting the styrene acrylic resin unit has a glass transition temperature of 50° C. or higher and a softening point of 105° C. or higher. The acid value, weight average molecular weight, glass transition temperature, and softening point of the styrene acrylic resin (A) can be measured by the methods 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 that is a polycondensation product of an alcohol component (b-al) and a carboxylic acid component (b-ac) as raw material monomers (b). The alcohol component (b-al) and the carboxylic acid component (b-ac) contained in the polyester resin will be described below.

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

[0032] Specific 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 numerical value in the parentheses above corresponds to the average value of the sum of x and y in the above formula (I).

[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 preferably has 2 or more carbon atoms, and preferably 18 or less, more preferably 14 or less, even more preferably 10 or less, and even more preferably 6 or less. 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 adducts of hydrogenated bisphenol A with alkylene oxides having 2 to 4 carbon atoms (average number of added moles: 2 to 12).

[0036] Examples of trihydric or higher polyhydric alcohols 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. From the viewpoint of adjusting the molecular weight and softening point of the resin, the alcohol component (b-al) may contain a monohydric alcohol. These alcohol components may be used alone or in combination of two or more.

[0037] Among these, the alcohol component (b-al) preferably contains one or more selected from aromatic diols and aliphatic diols having from 2 to 18 carbon atoms, more preferably contains 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 contains an alkylene oxide adduct of bisphenol A (BPA-AO).

[0038] The amount of BPA-AO in the alcohol component (b-al) 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 is 100 mol% or less, even more preferably 100 mol%.

[0039] (Carboxylic acid component (b-ac)) Examples of the carboxylic acid component (b-ac) include dicarboxylic acid compounds and trivalent or higher polycarboxylic acid compounds.

[0040] Examples of the dicarboxylic acid compound include aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and alicyclic dicarboxylic acid compounds. The dicarboxylic acid compound preferably has 2 or more carbon atoms, more preferably 3 or more carbon atoms, and preferably has 30 or less carbon atoms, more preferably 20 or less carbon atoms. 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 the aliphatic dicarboxylic acid compound include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, pentanedioic acid, adipic acid, sebacic acid, dodecanedioic acid, azelaic acid, and succinic acid substituted with an aliphatic hydrocarbon group having from 1 to 20 carbon atoms. Examples of succinic acids substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms include n-dodecenylsuccinic acid, isododecenylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, n-octenylsuccinic acid, n-octylsuccinic acid, isooctenylsuccinic acid, and isooctylsuccinic acid. An example of the alicyclic dicarboxylic acid compound is cyclohexanedicarboxylic acid.

[0041] Examples of trivalent or higher polycarboxylic acid compounds include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, and pyromellitic acid.

[0042] Among these, the carboxylic acid component (b-ac) preferably contains one or more selected from aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and trivalent or higher polycarboxylic acid compounds, more preferably contains one or more selected from terephthalic acid, isophthalic acid, maleic acid, fumaric acid, alkenylsuccinic acid, and trimellitic acid, even more preferably contains one or more selected from terephthalic acid, isophthalic acid, fumaric acid, and trimellitic acid, and even more preferably contains one or more aromatic dicarboxylic acid compounds selected from terephthalic acid and isophthalic acid. The amount of the aromatic dicarboxylic acid compound in the carboxylic acid component (b-ac) 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 is 100 mol% or less, even more preferably 100 mol%.

[0043] The carboxylic acid component (b-ac) may contain a trivalent or higher polycarboxylic acid compound as appropriate, from the viewpoint of controlling the degree of polymerization of the resin. The trivalent or higher polycarboxylic acid compound may be used in an amount of preferably 0.2 to 30% by mass, more preferably 0.5 to 20% by mass, based on the total amount of the raw material monomers (b) of the polyester resin (B).

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

[0045] (Production of Resin (B)) The resin (B) is preferably produced, for example, by a polycondensation reaction of raw material monomer (b) containing an alcohol component (b-al) and a carboxylic acid component (b-ac). From the viewpoint of further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability, the polycondensation reaction is more preferably carried out according to the following step I'. Step I': A step of obtaining a polyester resin (B) by polymerizing a raw material monomer (b) in a polymerization system independent of the polymerization system of the raw material monomer (a) constituting the styrene acrylic resin (A) constituting the styrene acrylic resin unit in the absence of the styrene acrylic resin (A) constituting the styrene acrylic resin unit.

[0046] The polycondensation reaction in step I′ may be carried out, as necessary, using an esterification catalyst such as tin(II) di(2-ethylhexanoate), dibutyltin oxide, or titanium diisopropylate bistriethanolamine in an amount of 0.01 to 5 parts by mass relative to 100 parts by mass of the total amount of raw material monomers (b); or an esterification promoter such as gallic acid (equivalent to 3,4,5-trihydroxybenzoic acid) in an amount of 0.001 to 0.5 parts by mass relative to 100 parts by mass of the total amount of raw material monomers (b). When a monomer having an unsaturated bond such as fumaric acid is used in the polycondensation reaction in step I', a radical polymerization inhibitor may be used, if necessary, in an amount of preferably 0.001 to 0.5 parts by mass per 100 parts by mass of the total amount of raw material monomer (b). Examples of the radical polymerization inhibitor include 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 is 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, 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, even more preferably 70°C or lower. The acid value of the polyester resin (B) is preferably 2 mgKOH / g or more, and preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and even more preferably 10 mgKOH / g or less. The hydroxyl value of the polyester resin (B) is preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more, even more preferably 40 mgKOH / g or more, and is preferably 80 mgKOH / g or less, more preferably 70 mgKOH / g or less, even more preferably 60 mgKOH / g or less. The softening point, glass transition temperature, acid value, and hydroxyl value of the polyester resin (B) can be measured by the methods described in the examples.

[0048] [Method of manufacturing binder resin for toner] The binder resin of the present invention contains a composite resin obtained by combining a styrene acrylic resin (A) constituting the styrene acrylic resin unit and a polyester resin (B) constituting the polyester resin unit. The method for producing a binder resin of the present invention is, from the viewpoint of further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability, Step I: A step of obtaining a styrene-acrylic resin (A) by polymerizing a raw material monomer (a) in a polymerization system different from the polymerization system of a raw material monomer (b) constituting the polyester-based resin (B) in the absence of a polyester-based resin (B) constituting the polyester-based resin unit; and Step II: A step of covalently bonding the styrene-acrylic resin (A) obtained in Step I with a polyester resin (B) to obtain a binder resin for toner containing the composite resin; It is preferred that the compound contains: The production of the styrene-acrylic resin (A) in step I is as described above.

[0049] The method for producing a binder resin of the present invention preferably further includes the step I′, from the viewpoint of further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability. The polyester resin (B) in step I' is produced as described above. When the present invention includes step I', step II is preferably a step of combining the styrene-acrylic resin (A) obtained in step I with the polyester-based resin (B) obtained in step I' via a covalent bond formed by a polymerization reaction to obtain a toner binder resin containing the composite resin. That is, the polymerization reaction in step II is preferably a condensation reaction between the styrene-acrylic resin (A) and the polyester-based resin (B), from the viewpoint of achieving sufficient composite formation and further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charge stability. As a result, the styrene-acrylic resin (A) and the polyester-based resin (B) are combined via a covalent ester bond to form a composite. Examples of such a condensation reaction include a condensation reaction between a carboxy group of the styrene-acrylic resin (A) and a hydroxy group of the polyester-based resin (B), or a condensation reaction between a hydroxy group of the styrene-acrylic resin (A) and a carboxy group of the polyester-based resin (B).

[0050] In Step II, from the viewpoint of achieving sufficient compounding and further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charge stability, it is preferable that the compounding of the styrene-acrylic resin (A) and the polyester-based resin (B) be carried out by forming a covalent bond via a compound (hereinafter also referred to as a "bireactive compound") that can react with both the raw material monomer (a) constituting the resin (A) and the raw material monomer (b) constituting the resin (B). That is, Step II is preferably a step of forming a covalent bond via a structural unit derived from a bireactive compound contained in either the styrene-acrylic resin (A) or the polyester-based resin (B) to obtain a binder resin for toner containing the composite resin, and more preferably a step of forming a covalent bond by a polymer reaction between the styrene-acrylic resin (A) and the polyester-based resin (B) via a structural unit derived from a bireactive compound contained in the styrene-acrylic resin (A) to obtain a binder resin for toner containing the composite resin.

[0051] The bireactive compound is preferably a compound that can react with both the raw material monomers of the styrene-acrylic resin (A) and the polyester-based resin (B), and more preferably a compound that can be complexed by forming an ester bond through a condensation reaction between the styrene-acrylic resin (A) and the polyester-based resin (B). Examples of such compounds include those represented by the following general formulas (II-1) and (II-2).

[0052] [ka] [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, an alkoxy group, an aryl group or a vinyl group which may have a substituent, or a halogen atom, which 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 represent -COOR 4 -OR 5 (R 4and R 5 represents a hydrogen atom or an optionally substituted lower alkyl group.

[0053] [ka] [In the formula, R 31 , R 32 and R 33 are the same or different and represent a hydrogen atom, a hydroxyl group, an alkyl group, an alkoxy group, an aryl group or a vinyl group which may have a substituent, or a 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 these bireactive compounds are capable of reacting with both the raw material monomers of the styrene-acrylic resin (A) and the polyester-based resin (B). However, when there are two or more types of raw material monomers for each of the styrene-acrylic resin (A) and the polyester-based resin (B), it is sufficient that the bireactive compounds are capable of reacting with at least one of them.

[0055] In the general formulae (II-1), (II-2), and (III-1) to (III-3), R 21 ~R 23 and R 31 ~R 33 Among the above, specific examples or preferred embodiments of the alkyl group, alkoxy group, aryl group, vinyl group, and halogen atom are as follows: The alkyl group is preferably a linear or branched alkyl group having from 1 to 6 carbon atoms, more preferably from 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and a tert-butyl group. These alkyl groups may be substituted with a phenyl group, a naphthyl group, a hydroxyl group, or the like. Examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, and a t-butoxy group, and these groups may be substituted with a hydroxyl group, a carboxyl group, or the like. Examples of the aryl group include a phenyl group, a benzyl group, and a naphthyl group, and these groups may be substituted with a methyl group, an ethyl group, a methoxy group, an ethoxy group, a carboxyl group, a hydroxyl group, or the like. 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 the formula (I) preferably has 1 to 4 carbon atoms, and examples thereof include a methyl group and an ethyl group, and these groups may be substituted with a hydroxyl group or the like.

[0056] When X in general formula (II-2) is a carboxy group, examples of the compound 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 is R 21 ~R 23 R represents a hydrogen atom, an alkyl group, an aryl group, or a vinyl group which may have a substituent, or a halogen atom, as in the above. 43 and R 44 are the same or different, R 21 ~R 23 A is the same as above, and represents an optionally substituted alkyl group, aryl group, or vinyl group, or a halogen atom. A is the same as above.

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

[0058] When X and Y in general formula (II-1) are carboxy groups, examples of the compound 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 is R 21 ~R 23 A and B are the same as those defined above, and each represents a hydrogen atom, an alkyl group, an aryl group, or a vinyl group which may have a substituent, or a halogen atom. A and B are the same as those defined above.

[0059] Specific examples of the 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 lower alkyl esters and anhydrides thereof.

[0060] When X in general formula (II-2) is a hydroxy group, preferred examples of the compound represented by general formula (II-2) include ethylenically unsaturated monoalcohols represented by the following general formulas (VI-1) to (VI-3). [ka] [In the formula, R 61 ~R 64 is R 21 ~R 23 represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group, as defined above. A is the same as defined above.

[0061] Specific examples of the 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 in general formula (II-1) are hydroxy groups, preferred examples of the compound 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 is R 21 ~R 23 A and B are the same as those defined above, and each represents a hydrogen atom, an alkyl group, an aryl group, or a vinyl group which may have a substituent, or a halogen atom. A and B are the same as those defined above.

[0063] As the bireactive compound, from the viewpoint of achieving sufficient complexation and further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability, an ethylenically unsaturated monocarboxylic acid compound is preferred, and acrylic acid is more preferred. The bireactive compound is preferably introduced into the polymer skeleton as a raw material monomer for either the styrene-acrylic resin (A) or the polyester-based resin (B) before composite formation, and then composited with the other resin via the bireactive compound. From the viewpoint of ensuring sufficient composite formation, it is more preferable to introduce the bireactive compound into the polymer skeleton as a raw material monomer (a) for the styrene-acrylic resin (A) before composite formation, and then composited with the polyester-based resin (B) via the bireactive compound. When the raw material monomer (a) for the styrene-acrylic resin (A) contains an ethylenically unsaturated monocarboxylic acid compound as the bireactive compound, the styrene-acrylic resin (A) is composited via an ester bond formed by a condensation reaction between a carboxy group introduced into the polymer skeleton due to the inclusion of a structural unit derived from the ethylenically unsaturated monocarboxylic acid compound and a hydroxy group of the polyester-based resin (B).

[0064] The amount of the bireactive compound capable of reacting with both the styrene acrylic resin (A) and 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, and even more preferably 5% by mass or more, relative to the total amount of raw material monomers (a) of the styrene acrylic resin (A) constituting the styrene acrylic resin unit, when the total amount of the raw material monomers (a) of the styrene acrylic resin (A) constituting the styrene acrylic resin unit is taken as 100% by mass, and is 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. That is, the amount of the bireactive compound 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 is 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, even more preferably 10 parts by mass or less, relative to 100 parts by mass of the total amount of raw material monomer (a).

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

[0066] When Step II is carried out by a polymer reaction, the method is not particularly limited as long as it is a method capable of forming a covalent bond, but a method in which the styrene-acrylic resin (A) and the polyester-based resin (B) are heated, melted, and mixed 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, even more preferably 200°C or lower. The polymer reaction in step II may be carried out under increased or reduced pressure from the viewpoint of reactivity, but is preferably carried out at normal pressure from the viewpoint of ease of reaction. The time for the polymer reaction may be appropriately changed depending on the reaction temperature, etc., but is preferably 1 hour or more and 24 hours or less, more preferably 12 hours or less, and even more preferably 6 hours or less.

[0067] From the viewpoint of further improving low-temperature fixability, hot offset resistance, heat-resistant storage stability, and charging stability, 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 is 100% by mass or less, even more preferably 100% by mass or less.

[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, and even more preferably 110°C or higher, and is 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 mgKOH / g or less, more preferably 40 mgKOH / g or less, even more preferably 35 mgKOH / g or less, and even more preferably 30 mgKOH / g or less. On the other hand, the acid value of the binder resin of the present invention is preferably 2 mgKOH / g or more, more preferably 8 mgKOH / g or more, even more preferably 14 mgKOH / g or more, and even more preferably 20 mgKOH / 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. In the case of using two or more binder resins of the present invention in combination, for example, two binder resins having different softening points are used. The difference in softening point between the binder resin having a low softening point and the binder resin having a high softening point is preferably 5° C. or more, more preferably 7° C. or more, and even more preferably 10° C. or more, and is preferably 40° C. or less, more preferably 30° C. or less, and even more preferably 20° C. or less. When a binder resin having a low softening point and a resin having a high softening point are used in combination, the mixing ratio of the binder resin having a low softening point to the binder resin having a high softening point (binder resin having a low softening point / binder resin having a high softening point) 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] [Electrostatic image developing toner] 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. The toner contains, for example, toner particles and external additives. The toner particles preferably contain the binder resin. The toner particles may contain, for example, a colorant, a colorant derivative, a release agent such as wax, a charge control agent, a magnetic material, and other additives. Of these, the toner particles preferably contain a colorant.

[0071] <Coloring agent> The colorant may be either a pigment or a dye. Examples of colorants include various carbon blacks produced by the thermal black method, acetylene black method, channel black method, lamp black method, etc.; grafted carbon black in which the surface of carbon black is coated with a resin; nigrosine dyes; phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment green B, pigment blue 15:3, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, etc.; and mixtures thereof. From the viewpoint of improving the image density of the toner, the content of the colorant is preferably 1 part by mass to 15 parts by mass, more preferably 2 parts by mass 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 chargeable charge control agent or a negatively chargeable charge control agent. These charge control agents may be used alone or in combination of two or more.

[0073] Examples of positively chargeable charge control agents include nigrosine dyes, triphenylmethane 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 Industries, Ltd.). Examples of quaternary ammonium salt compounds include "Bontron P-51" (manufactured by Orient Chemical Industries, Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX VP435" (manufactured by Hoechst). Examples of polyamine resins include "AFP-B" (manufactured by Orient Chemical Industries, Ltd.). Examples of imidazole derivatives include "PLZ-2001" and "PLZ-8001" (both manufactured by Shikoku Chemical Industries, Ltd.). Examples of styrene-acrylic resins include "FCA-701PT" (manufactured by Fujikura Chemical Industries, Ltd.). Among these, Bontron N-07 can be preferably used.

[0074] Specific examples of negatively chargeable charge control agents include metal-containing azo dyes, metal compounds of benzilic 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 "Balifast Black 3804," "Bontron S-31" (all manufactured by Orient Chemical Industry Co., Ltd.), "T-77" (manufactured by Hodogaya Chemical Industry Co., Ltd.), "Bontron S-32," "Bontron S-34," and "Bontron S-36" (all manufactured by Orient Chemical Industry Co., Ltd.), and "Eisenspiron Black TRH" (manufactured by Hodogaya Chemical Industry 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 Industry Co., Ltd.). Examples of quaternary ammonium salts include "COPY CHARGE NX VP434" (manufactured by Hoechst). Examples of organometallic compounds include "TN105" (manufactured by Hodogaya Chemical Industry Co., Ltd.). Among these, Bontron E-81, Bontron S-34, T-77, and Aizenspiron Black TRH can be preferably used.

[0075] The content of the charge control agent is preferably 0.1 parts by mass or more and 8 parts by mass or less, more preferably 0.2 parts by mass or more and 5 parts by mass or less, relative to 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 preventing 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. Those with relatively low molecular weights, particularly those with a molecular weight of 3,000 to 15,000 as determined by the vapor permeation method, are preferred. Those with a softening point of 70°C to 150°C, particularly 120°C to 150°C as determined by the ring and ball method, are also preferred.

[0077] <Other additives> The toner particles may further contain, as other additives, additives such as magnetic powder, a flowability improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, an antiaging agent, and a cleaning property improver, as appropriate.

[0078] In the toner of the present invention, the content of toner particles is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and is 100% by mass or less, preferably 99% by mass or less.

[0079] The volume median particle size of the toner particles (D 50 ) is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and is preferably 20 μm or less, more preferably 15 μm or less, even more preferably 10 μm or less. 50 ) means the particle size at which the cumulative volume frequency calculated by volume fraction is 50% calculated from the smallest particle size.

[0080] <External additives> In order to improve fluidity, the toner of the present invention may contain both toner particles and external additives by treating the surfaces of the toner particles with a property improver such as an external additive. Examples of external additives include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin fine particles such as melamine-based resin fine particles and polytetrafluoroethylene resin fine particles. These may be used alone or in combination. 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 the toner particles are surface-treated using an external additive, the content of the external additive is, from the viewpoint of the chargeability and flowability of the toner, 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 is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, relative to 100 parts by mass of the toner particles.

[0083] [Toner manufacturing method] The toner of the present invention may be a toner obtained by any known method such as a melt-kneading method, an emulsion phase inversion method, a suspension polymerization method, or an emulsion aggregation method. However, from the viewpoint of productivity and dispersibility of the colorant, a pulverized toner obtained by a melt-kneading method is preferred. In the melt-kneading method, the binder resin, the colorant, and, if necessary, the property improver are uniformly dispersed, and then the mixture is melt-kneaded, cooled, pulverized, and classified by a known method to obtain a volume median particle size (D 50 ) Toner having a particle size 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, etc. The toner can be used as a non-magnetic one-component developer, or as a dry two-component developer by mixing with a carrier such as an iron oxide carrier, a spherical iron oxide carrier, or a ferrite carrier, either directly or coated with a resin or the like. [Example]

[0085] [measurement] [Acid value and hydroxyl value of resin] 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 tetrahydrofuran for measuring the hydroxyl value.

[0086] [Weight average molecular weight of resin] The molecular weight distribution was measured by gel permeation chromatography (GPC) obtained by 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, and then filtered through a 2 μm fluororesin filter "FP-200" (manufactured by Sumitomo Electric Industries, Ltd.) to remove insoluble components, leaving a sample solution. (2) Measurement of weight-average molecular weight The following measurement equipment and analytical column were used, and tetrahydrofuran was used as the eluent at a flow rate of 1 mL per minute. The column was stabilized in a thermostatic bath at 40°C. 100 μL of sample solution was injected into the column for measurement. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. The calibration curve used here included several types of monodisperse polystyrene ("A-500" manufactured by Tosoh Corporation) (Mw: 5.0 × 10 2 ), "A-1000" (Mw: 1.01 x 10 3 ), "A-2500" (Mw:2.63×10 3 ), "A-5000" (Mw: 5.97 x 103 ), "F-1" (Mw: 1.02 × 10 4 ), "F-2" (Mw: 1.81 x 10 4 ), "F-4" (Mw: 3.97 x 10 4 ), "F-10" (Mw: 9.64 × 10 4 ), "F-20" (Mw:1.90×10 5 ), "F-40" (Mw: 4.27 x 10 5 ), "F-80" (Mw:7.06×10 5 ), "F-128" (Mw: 1.09 x 10 6 )) was used as a standard sample. The molecular weight is indicated in parentheses. Measuring device: "HLC-8220GPC" (Tosoh Corporation) Analytical column: "GMHXL" + "G3000HXL" (manufactured by Tosoh Corporation)

[0087] [Glass transition temperature of resin] Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.01-0.02 g of sample was weighed into an aluminum pan, heated to 200°C, and cooled to 0°C at a rate of 10°C / min. The sample was then heated to 150°C at a rate of 10°C / min, and the glass transition temperature was determined as 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 rising part of the peak to the peak apex.

[0088] [Softening point of resin] Using a flow tester "CFT-500D" (Shimadzu Corporation), 1 g of sample was heated at a temperature increase rate of 6°C / min, while applying a load of 1.96 MPa with the plunger, and extruded from a nozzle 1 mm in diameter and 1 mm in length. The plunger depression distance of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point.

[0089] [Melting point of release agent] Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.02 g of sample was weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a rate of 10°C / min. The sample was then heated at a rate of 10°C / min, and the calorific value was measured. The maximum endothermic peak temperature was taken as the melting point.

[0090] [Volume median particle size of toner particles (D 50 ) The volume median particle size of the toner particles (D 50 ) was measured as follows. Measurement 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" (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 measurement sample was added to 5 mL of the dispersion liquid, and dispersed for 1 minute using an ultrasonic disperser. Then, 25 mL of electrolyte was added, and the mixture was further dispersed for 1 minute using an ultrasonic disperser to prepare a sample dispersion liquid. Measurement conditions: In a beaker, the sample dispersion is added to 100 mL of the electrolyte to adjust the concentration so that the particle diameter of 30,000 particles can be measured in 20 seconds. Then, 30,000 particles are measured, and the volume median particle diameter (D 50 ) was sought.

[0091] [Production of Resin (A) and Resin (B)] Production Examples A1 to A5, Comparative Production Example A51 (Production of Resins A-1 to A-5, A-51) The raw material monomers for styrene-acrylic resins containing acrylic acid as a bireactive compound shown in Table 1 were placed in an autoclave equipped with a stainless steel stirring rod, and the raw material monomers were polymerized under pressurized and heated conditions (300°C) for 2 hours. The pressure and temperature were returned to normal, and the precipitated styrene-acrylic resins were collected, yielding styrene-acrylic resins A-1 to A-5 and A-51.

[0092] Manufacturing Example A6 (Manufacturing of Manufacturing A-6) The raw material monomers for styrene-acrylic resin containing acrylic acid as the bireactive compound shown in Table 1 and a radical generator were placed in a stainless steel reaction vessel equipped with a thermometer, a stainless steel stirring rod, a downflow condenser equipped with a dehydration tube, and a nitrogen inlet tube, and the raw material monomers were polymerized at 150°C for 2 hours. The temperature was returned to room temperature, and the precipitated styrene-acrylic resin was collected, yielding styrene-acrylic resin A-6.

[0093] [Table 1]

[0094] Production Examples B1 to B4 (Production of Resins B-1 to B-4) The raw material monomers, esterification catalyst, and cocatalyst for the polyester resins shown in Table 2 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirrer, a downflow 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 to 230°C. After confirming that all solid monomers had melted and reacted, the pressure was reduced to 60 torr and dehydration condensation was carried out for 1 hour. The pressure was then returned to normal, cooled to 160°C, heated to 220°C, and maintained at 220°C for another hour. The condensation reaction was then carried out at 220°C and 60 torr until the softening point reached the softening point shown in Table 2, yielding Resins B-1 to B-4.

[0095] [Table 2]

[0096] [Manufacturing of binder resin] 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-based resin (B) combinations and mixing ratios shown in Table 3 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser with a dehydration tube, and a nitrogen inlet tube. The mixture was heated to 180°C in a nitrogen atmosphere for 4 hours to melt and mix the styrene-acrylic resin (A) and polyester-based resin (B) for a condensation reaction. The temperature was then further increased to 230°C and the reaction continued for 1 hour, after which the pressure was reduced to 60 torr. Once the softening points of the resins reached the predetermined softening points shown in Table 3, the reaction was stopped to form composite resins, yielding binder resins C-1 to C-11 and C-51.

[0097] [Table 3]

[0098] Comparative Example 1-2 (Production of Binder Resin C-52) The raw material monomers for the polyester resin unit (excluding trimellitic anhydride) shown in Table 4, the bireactive compound acrylic acid, the esterification catalyst, and the cocatalyst were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirrer, a downflow condenser with a dehydration tube, and a nitrogen inlet tube, and heated to 160°C under a nitrogen atmosphere. A mixed solution of the raw material monomers for the styrene-acrylic resin unit and a polymerization initiator shown in Table 4 was added dropwise over 1 hour. After the dropwise addition, the temperature was raised to 200°C and the reaction was allowed to mature for 1 hour, producing a styrene-acrylic resin in the reaction system. The temperature was then raised every hour to 230°C, and after confirming that all solid monomers had melted and reacted, the pressure was reduced to 60 torr and dehydration-condensation was allowed to proceed for 1 hour. Trimellitic anhydride was then added, and the dehydration-condensation reaction was continued at 230°C until the softening point reached the softening point shown in Table 4, yielding 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 weight of the binder resins shown in Table 5, 1 part by weight of a negatively chargeable charge control agent "Bontron E-81" (manufactured by Orient Chemical Industry Co., Ltd.), 5 parts by weight of a colorant "Pigment Blue 15:3" (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), and 2 parts by weight of a mold release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80°C) were thoroughly mixed in a Henschel mixer, and then melt-kneaded using a co-rotating twin-screw extruder with a total length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm at a screw rotation speed of 200 r / min and a barrel temperature setting of 100°C. The feed rate of the mixture was 20 kg / h, and the average residence time was approximately 18 seconds. The resulting melt-kneaded product was cooled, coarsely crushed, crushed in a jet mill, and classified to determine the volume median particle size (D 50 ) toner particles of 8 μm were obtained.

[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., number average particle diameter: 16 nm) was added, and the mixture was mixed in a Henschel mixer at 3600 r / min for 5 minutes to perform external additive treatment and obtain a toner.

[0102] [Toner Evaluation] [Low temperature fixability and hot offset resistance] Each toner was mounted in a copy machine "AR-505" (manufactured by Sharp Corporation) whose fixing unit was modified to enable fixing outside the machine, and a printout was obtained in an unfixed state (print area: 2 cm × 12 cm, adhesion amount: 0.5 mg / cm 2). Then, using a fixing machine (fixing speed: 300 mm / sec) adjusted to a total fixing pressure of 40 kgf, the temperature of the fixing roll was raised in 5°C increments from 80°C to 240°C, and a fixing test was conducted on the unfixed print at each temperature. Cellophane adhesive tape "UNICEF Cellophane" (manufactured by Mitsubishi Pencil Co., Ltd., width: 18 mm, JIS Z1522) was applied to the image portion of the resulting print. The print was passed through a fixing roll set at 30°C, and then the tape was peeled off. The optical reflection density before and after tape application was measured using a reflection densitometer "RD-915" (manufactured by Gretag Macbeth). The temperature of the fixing roll at which the ratio (after peeling / before application x 100) first exceeded 90% was defined as the minimum fixing temperature. The lower the minimum fixing temperature, the better the low-temperature fixability. The fixed image obtained above was visually inspected, and the lowest temperature of the fixing roll at which hot offset was observed was recorded as the hot offset temperature. 2 The higher the hot offset temperature, the better the hot offset resistance. These results are shown in Table 5.

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

[0104] [Charge stability] Under conditions of a temperature of 32°C and a relative humidity of 50%, 0.6 g of each toner and 19.4 g of silicone ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd., average particle size 90 μm) were placed in a 50 mL polyvinyl chloride bottle and mixed using a ball mill at 250 r / min. The charge amount of the toner was measured using a Q / M meter (manufactured by EPPING Co., Ltd.) using the following method. After the specified mixing time, a specified amount of toner and carrier mixture was placed in a cell attached to the Q / M meter, and the toner alone was sucked through a 32 μm mesh sieve (stainless steel, twill weave, wire diameter: 0.0035 mm) for 90 seconds. The voltage change on the carrier that occurred at this time was monitored, and the value of X = [total amount of electricity after 90 seconds (μC) / amount of sucked toner (g)] was taken as the charge amount (μC / g). The charge amount X after 60 seconds of mixing 60 and the charge amount X after 600 seconds of mixing 600 Ratio to (X 60 / X 600 ) was calculated, and the charge stability was evaluated according to the following evaluation criteria. The larger the value, the better the 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 more B: Ratio (X 60 / X 600 ) is 0.80 or more 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 of the examples using binder resins containing specific composite resins have lower minimum fixing temperatures and higher hot offset temperatures than the toners of the comparative examples, and therefore are excellent in low-temperature fixing properties and hot offset resistance, as well as in heat-resistant storage stability and charging stability.

Claims

1. A binder resin for toner containing a composite resin in which a styrene-acrylic resin unit and a polyester resin unit are bonded via a covalent bond, The binder resin for toner, wherein the styrene acrylic resin (A) constituting the styrene acrylic resin unit has an acid value of 40 mgKOH / g or more.

2. 2. The binder resin for toner according to claim 1, wherein the composite resin is a resin obtained by forming a covalent bond by a polymer reaction between the styrene-acrylic resin (A) and the polyester resin (B) constituting the polyester resin unit.

3. 3. The binder resin for toner according to claim 2, wherein the polymerization systems of the styrene-acrylic resin (A) and the polyester resin (B) are independent reaction systems.

4. 4. The binder resin for toner according to claim 1, wherein the styrene-based acrylic resin (A) is formed by bulk polymerization.

5. 5. The binder resin for toner according to claim 4, wherein the concentration of the radical generator in the bulk polymerization of the styrene-acrylic resin (A) is 1% by mass or less based on the total amount of the raw material monomers (a) of the styrene-acrylic resin (A).

6. 6. The binder resin for toner according to claim 4, wherein the styrene-acrylic resin (A) is bulk polymerized in the absence of a solvent.

7. 7. The binder resin for toner according to claim 4, wherein the styrene-acrylic resin (A) is bulk polymerized in the absence of a catalyst.

8. 8. The binder resin for toner according to claim 4, wherein the styrene-acrylic resin (A) is bulk polymerized at a temperature of 160° C. or higher.

9. 9. The binder resin for toner according to claim 1, 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.

10. 10. A toner for developing electrostatic images, comprising the binder resin for toner according to claim 1.

11. A method for producing a binder resin for toner containing a composite resin in which a styrene-acrylic resin unit and a polyester resin unit are bonded via a covalent bond, comprising: Step I: A step of obtaining a styrene-acrylic resin (A) by polymerizing a raw material monomer (a) in a polymerization system independent of a polymerization system of a raw material monomer (b) constituting the polyester-based resin unit in the absence of a polyester-based resin (B) constituting the polyester-based resin unit; and Step II: A step of covalently bonding the styrene-acrylic resin (A) obtained in Step I with a polyester resin (B) to obtain a binder resin for toner containing the composite resin; Including, The method for producing a binder resin for toner, wherein the styrene-acrylic resin (A) has an acid value of 40 mgKOH / g or more.

12. The method for producing a binder resin for toner according to claim 11, further comprising the following step I': Step I': A step of obtaining a polyester resin (B) by polymerizing a raw material monomer (b) in a polymerization system independent of the polymerization system of the raw material monomer (a) constituting the styrene acrylic resin (A) in the absence of the styrene acrylic resin (A) constituting the styrene acrylic resin unit.

13. 13. The method for producing a binder resin for toner according to claim 12, wherein step II is a step of bonding the styrene-acrylic resin (A) obtained in step I with the polyester-based resin (B) obtained in step I′ via a covalent bond formed by a polymer reaction between the two to obtain a binder resin for toner containing the composite resin.

14. 14. The method for producing a binder resin for toner according to claim 11, wherein the polymer reaction in step II is a condensation reaction.

15. 15. The method for producing a binder resin for toner according to claim 11, wherein the polymerization of the raw material monomer (a) in step I is bulk polymerization.

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