Binder resin for toner

Abstract

A binder resin for toner, which 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, and the acid value of the styrene-acrylic resin (A) constituting the above styrene-acrylic resin unit is 40 mgKOH / g or more.

Description

Technical Field

[0001] The present invention relates to a binder resin for a toner, which is used for developing a latent image formed by electrophotography, electrostatographic recording, electrostatic printing, or the like. Background Art

[0002] In recent years, in the field of electrophotography, with the development of electrophotographic systems, there has been a demand for developing an electrostatic image developing toner corresponding to high image quality and high-speed printing. In response to such a demand, a polyester resin has been proposed as a binder resin for a toner having excellent low-temperature fixability.

[0003] The minimum fixing temperature is generally in the temperature range from the temperature at which low-temperature offset occurs to the temperature at which high-temperature offset occurs. Therefore, the usable temperature range of the binder resin is the temperature range from the minimum fixing temperature to the temperature at which high-temperature offset occurs. Therefore, by reducing the minimum fixing temperature as much as possible and increasing the temperature at which high-temperature offset occurs, it is possible to lower the fixing temperature used and expand the usable temperature range, and it is possible to meet the requirements of energy saving and high-speed fixing. Therefore, there is a high demand for a binder resin for a toner and a toner having excellent low-temperature fixability and resistance to offset.

[0004] However, although the polyester resin has excellent low-temperature fixability, there is a problem that offset is likely to occur.

[0005] Under such circumstances, Japanese Patent Application Laid-Open No. 2008-102396 (Patent Document 1) discloses a toner in which the binder resin of the toner particles contains a low softening point resin and a high softening point resin. The low softening point resin is 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, or a resin obtained by polycondensing a polycondensation monomer in the presence of a vinyl resin obtained by addition-polymerizing a vinyl monomer. The high softening point resin is a resin obtained by adding and mixing a vinyl monomer to a polycondensation resin obtained by polycondensing a polycondensation monomer and then performing addition-polymerization. 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 in a specified range. It is also disclosed that a toner having excellent low-temperature fixability, high-temperature offset resistance, and developability can be obtained.

[0006] Japanese Patent Application Laid-Open No. 2018-10124 (Patent Document 2) discloses a toner that can obtain excellent low-temperature fixability, storage stability, and control of fusion of the toner to a photosensitive drum. The toner has toner particles containing a binder resin and a colorant, and the binder resin is a hybrid resin obtained by chemically bonding a polyester unit and a vinyl polymer unit obtained by polymerizing a vinyl monomer in the absence of a polyester unit and its raw materials. Summary of the Invention

[0007] The present invention relates to a binder resin for toner, which 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.

[0008] The acid value of the styrene acrylic resin (A) constituting the above styrene acrylic resin unit is 40 mgKOH / g or more. Detailed Description of the Invention

[0009] In the toner disclosed in Patent Document 1, since a vinyl resin obtained by addition polymerization of a vinyl monomer in the presence of a polycondensation monomer or a polycondensation resin is used, there are problems in controlling the molecular weight, molecular weight distribution, and monomer copolymerizability.

[0010] In addition, for the toner disclosed in Patent Document 2, since the acid value of the vinyl polymer constituting the hybrid resin is low, the hybridization is insufficient, and there are problems in heat-resistant storage stability, charge stability, etc.

[0011] The present invention relates to a binder resin for toner, an electrostatic image developing toner, and a method for manufacturing a binder resin for toner, which are excellent in low-temperature fixability, heat-resistant offset property, heat-resistant storage stability, and charge stability.

[0012] The present inventors have found that for a binder resin for toner containing a composite resin in which a polyester resin unit excellent in low-temperature fixability and a styrene acrylic resin unit excellent in chargeability and heat-resistant offset property are bonded via a covalent bond, by optimizing the molecular weight, molecular weight distribution, and monomer copolymerizability of the styrene acrylic resin constituting the composite resin and setting it to have an acid value of a specified value or more, the composite with the polyester resin unit can be made sufficient. Focusing on this, a binder resin for toner, an electrostatic image developing toner, and a method for manufacturing a binder resin for toner, which are excellent in low-temperature fixability, heat-resistant offset property, heat-resistant storage stability, and charge stability, can be provided.

[0013] That is, the present invention relates to the following embodiments [1] to [3].

[0014] 〔1〕A binder resin for toner, which 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.

[0015] The acid value of the styrene acrylic resin (A) constituting the above styrene acrylic resin unit is 40 mgKOH / g or more.

[0016] [2] A toner for electrostatic image development, which contains the binder resin for toner described in the above [1].

[0017] [3] A method for manufacturing a binder resin for toner, which is a method for manufacturing 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 above manufacturing method includes:

[0018] Step I: A step of polymerizing a raw material monomer (a) in an independent polymerization system different from the polymerization system of the raw material monomer (b) constituting the polyester resin (B) of the polyester resin unit in the absence of the polyester resin (B) constituting the polyester resin unit, to obtain a styrene-acrylic resin (A), and

[0019] 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 above composite resin.

[0020] The acid value of the above styrene-acrylic resin (A) is 40 mgKOH / g or more.

[0021] According to the present invention, it is possible to provide a binder resin for toner, a toner for electrostatic image development, and a method for manufacturing a binder resin for toner, which are excellent in low-temperature fixability, heat resistance to offset, heat storage stability, and charge stability.

[0022] [Binder resin for toner]

[0023] The binder resin for toner of the present invention (hereinafter, also referred to as "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 a covalent bond.

[0024] And, the acid value of the styrene-acrylic resin (A) constituting the above styrene-acrylic resin unit is 40 mgKOH / g or more.

[0025] The toner according to the present invention exhibits low-temperature fixability, heat resistance to offset, heat storage stability, and charge stability.

[0026] The reason for obtaining the effects of the present invention is not yet certain, but it is considered as follows.

[0027] The styrene-acrylic resin unit of the composite resin contained in the adhesive resin of the present invention is composed of a styrene-acrylic resin obtained in the absence of a polyester resin constituting the polyester resin unit and a raw material monomer constituting the polyester resin. Therefore, it is considered that the polymerization site of the raw material monomer of the styrene-acrylic resin is not the polyester resin or the polycondensation monomer as in the past, and thus the original polymerization performance of the raw material monomer of the styrene-acrylic resin is exerted, and a more uniform styrene-acrylic resin unit with controlled molecular weight, molecular weight distribution, and monomer copolymerizability can be formed. Moreover, by setting 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 compounding with the polyester resin constituting the polyester resin unit can be achieved. It is considered that through their synergistic effects, the molecular motion at low temperatures and the control of the entanglement of polymer chains at high temperatures of the composite resin become easy, and a resin with low viscosity at low temperatures and high elasticity at high temperatures, that is, a resin in which the high viscosity at low temperatures is suppressed and the low elasticity at high temperatures is suppressed, can be produced, improving low-temperature fixability, offset resistance, heat storage stability, and charge stability.

[0028] The definitions of various terms in this specification are shown below.

[0029] "Polyester resin" may include a polyester resin modified to such an extent that its properties are not substantially impaired. As the modified polyester resin, for example, a urethane-modified polyester resin obtained by modifying the polyester resin with a urethane bond and an epoxy-modified polyester resin obtained by modifying the polyester resin with an epoxy bond can be cited.

[0030] "Bisphenol A" means 2,2-bis(4-hydroxyphenyl)propane.

[0031] Examples of the "carboxylic acid compound" include carboxylic acids, their acid anhydrides, and alkyl esters having 1 or more and 3 or less carbon atoms. It should be noted that the carbon number of the alkyl group of the alkyl ester is not included in the carbon number of the carboxylic acid compound.

[0032] "Adhesive resin" means the adhesive resin component in the toner containing the composite resin.

[0033] The toner of the present invention contains a colorant and an adhesive resin.

[0034] The toner of the present invention contains, for example, toner particles and an external additive.

[0035] The toner particles preferably contain a colorant and an adhesive resin.

[0036] Moreover, the toner particles may contain, for example, a release agent, a colorant derivative, a charge control agent, and other additives.

[0037] <Composite resin>

[0038] The composite resin is a resin formed by covalently bonding a styrene-acrylic resin unit and a polyester resin unit.

[0039] Moreover, from the viewpoints of improving low-temperature fixability, heat resistance shift, heat storage stability, and charge stability, the acid value of the styrene-acrylic resin (A) constituting the above styrene-acrylic resin unit is 40 mgKOH / g or more.

[0040] And, regarding the compounding method using the formation of a covalent bond between the styrene-acrylic resin unit and the polyester resin unit, from the viewpoints of controlling the molecular weight, molecular weight distribution, and copolymerizability of monomers, and improving low-temperature fixability, heat resistance shift, heat storage stability, and charge stability, there can be mentioned a method (i) using a polymer reaction between the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit and the polyester resin (B) constituting the polyester resin unit, or a method (ii) using a reaction between the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit and the raw material monomer (b) of the polyester resin unit.

[0041] Among them, from the viewpoints of controlling the molecular weight, molecular weight distribution, and copolymerizability of monomers, and improving low-temperature fixability, heat resistance shift, heat storage stability, and charge stability, the above method (i) using a polymer reaction is preferred.

[0042] In the case of method (i), since the compounding method is a method using a polymerization reaction, regarding the polymerization systems of the styrene-acrylic resin (A) and the polyester resin (B) respectively, it is preferred to carry out the polymerization reaction in independent reaction systems. It is preferred that the polymerization system of the styrene-acrylic resin (A) is an addition polymerization type, and the polymerization system of the polyester resin (B) is a polycondensation type. The so-called 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 different reaction sites. That is, it means that 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).

[0043] If the respective 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 reaction temperature and time can be appropriately selected according to the respective reaction mechanisms to promote and complete the reaction.

[0044] In addition, 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, it can be carried out by separating the polyester resin (B) and then mixing it with the styrene acrylic resin (A), or it can also be carried out by continuously adding and mixing the styrene acrylic resin (A) without separating the polyester resin (B).

[0045] [Styrene acrylic resin (A)]

[0046] (Raw material monomer (a))

[0047] From the viewpoints of improving low-temperature fixability, heat resistance offset, heat storage stability, and charge stability, the styrene acrylic resin (A) is a resin of the styrene acrylic resin unit constituting the composite resin, and is an addition polymer of a raw material monomer (a) containing a styrene compound and a (meth)acrylic monomer.

[0048] Examples of the styrene compound include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-chlorostyrene, vinylnaphthalene, and other styrene and styrene derivatives. Styrene and α-methylstyrene are preferred.

[0049] Examples of the (meth)acrylic monomer include acrylic acid, methacrylic acid, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid n-propyl ester, (meth)acrylic acid isopropyl ester, (meth)acrylic acid n-butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid tert-butyl ester, (meth)acrylic acid pentyl ester, (meth)acrylic acid cyclohexyl ester, (meth)acrylic acid n-octyl ester, (meth)acrylic acid isooctyl ester, (meth)acrylic acid decyl ester, (meth)acrylic acid lauryl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid stearyl ester, (meth)acrylic acid 2-methoxyethyl ester, (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid glycidyl ester, (meth)acrylic acid 2-chloroethyl ester, (meth)acrylic acid phenyl ester, (meth)acrylic acid 2-(dimethylamino)ethyl ester, (meth)acrylic acid 2-(diethylamino)ethyl ester, α-chloroacrylic acid methyl ester, and other (meth)acrylic acids and (meth)acrylic acid derivatives.

[0050] It should be noted that "(meth)acrylate" means including both acrylate and methacrylate.

[0051] Among them, acrylic acid and methacrylic acid are preferred, and acrylic acid is more preferred.

[0052] The raw material monomer (a) may contain other monomers in addition to the styrene compound and the (meth)acrylic monomer.

[0053] As other monomers, for example, there may be mentioned olefinically unsaturated monoolefins such as ethylene, propylene, butene, isobutene, etc.; diolefins such as butadiene, etc.; vinyl halides such as vinyl chloride, vinyl bromide, vinyl fluoride, etc.; vinyl esters such as vinyl acetate, vinyl propionate, vinyl formate, vinyl caproate, etc.; vinyl ethers such as vinyl methyl ether, etc.; vinylidene halides such as vinylidene chloride; N-vinyl compounds such as N-vinyl pyrrole, N-vinyl pyrrolidone, etc.

[0054] The raw material monomer (a) preferably contains one or more styrene compounds selected from styrene and α-methylstyrene, and one or more (meth)acrylic acid-based 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 also contain other monomers such as propylene.

[0055] From the viewpoints of improving low-temperature fixability, heat resistance to offset, heat resistance to storage, and charge stability, 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 the styrene compound 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, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 85% by mass or more, further preferably 90% by mass or more, and preferably 98% by mass or less, more preferably 96% by mass or less, further preferably 94% by mass or less.

[0056] From the viewpoints of improving low-temperature fixability, heat resistance to offset, heat resistance to storage, and charge stability, the content of the (meth)acrylic acid-based 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 acid-based monomer 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, further preferably 6% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, further preferably 20% by mass or less, further preferably 15% by mass or less, further preferably 10% by mass or less.

[0057] From the viewpoints of improving low-temperature fixability, heat resistance to offset, heat storage stability, and charge stability, the total content of the styrene compound and the (meth)acrylic acid-based monomer in the raw material monomer (a) constituting the styrene acrylic resin (A), or the total content of the structural unit derived from the styrene compound and the structural unit derived from the (meth)acrylic acid-based 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, still more preferably 99% by mass or more, and is 100% by mass or less, and still more preferably 100% by mass.

[0058] (Manufacture of Resin (A))

[0059] In the present invention, from the viewpoints of controlling the molecular weight, molecular weight distribution, and copolymerizability of monomers, and improving low-temperature fixability, heat resistance to offset, heat storage stability, and charge stability, the styrene acrylic resin (A) constituting the styrene acrylic resin unit is preferably polymerized by an independent polymerization system different 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 above viewpoints, the polymerization method of the styrene acrylic resin (A) may be a polymerization method capable of controlling the molecular weight, molecular weight distribution, and copolymerizability of monomers in addition to the bulk polymerization method, such as solution polymerization, suspension polymerization, and emulsion polymerization. That is, from the above viewpoints, if 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 covalently bonded, and the acid value of the styrene acrylic resin (A) constituting the above styrene acrylic resin unit is 40 mgKOH / g or more, the polymerization method of the styrene acrylic resin (A) is not particularly limited.

[0060] From the viewpoint of ease of controlling the molecular weight, molecular weight distribution, and copolymerizability of monomers, the styrene acrylic resin (A) is preferably formed by the following step I.

[0061] Step I: A step of polymerizing the raw material monomer (a) in an independent polymerization system different 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 to obtain the styrene acrylic resin (A)

[0062] From the viewpoint of ease of controlling the molecular weight, molecular weight distribution, and copolymerizability of monomers, the styrene acrylic resin (A) is preferably formed by bulk polymerization or solution polymerization, and 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, and more preferably bulk polymerization.

[0063] In the present invention, "bulk polymerization" refers to addition polymerization carried out under conditions where substantially no solvent exists in the reaction system, i.e., under solvent-free conditions.

[0064] In the case where the polymerization in Step I is bulk polymerization, a radical generator can be used.

[0065] 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).

[0066] From the viewpoints of controlling the molecular weight, molecular weight distribution, and copolymerizability, and further improving the low-temperature fixability, heat resistance shift, heat resistance storage stability, and charge stability, when the total amount of the raw material monomers (a) of the styrene acrylic resin (A) is set to 100% by mass, with respect to the total amount of the raw material monomers (a), the concentration of the radical generator in bulk polymerization is preferably 7% by mass or less, more preferably 5% by mass or less, still more preferably 2% by mass or less, still more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and still more preferably 0% by mass. That is, with respect to 100 parts by mass of the total amount of the raw material monomers (a), it is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 2 parts by mass or less, still more preferably 1 part by mass or less, still more preferably 0.5 part by mass or less, and still more preferably 0 part by mass. That is, it is preferably carried out under catalyst-free conditions.

[0067] The bulk polymerization (in the case where the polymerization in Step I is bulk polymerization) is preferably carried out at a high temperature under a pressurized state of normal pressure or higher, and more preferably continuous bulk polymerization under high temperature and high pressure.

[0068] In the present invention, the pressurized state refers to a state in which the content is heated to a temperature above the boiling point at normal pressure in a closed container such as an autoclave.

[0069] Under a pressurized state of normal pressure or higher and at a high temperature, the radicals generated by the thermal initiation reaction of the raw material monomers (a) act as polymerization initiators, so that the addition polymerization can be promoted even under conditions where the radical generator is less, and a styrene acrylic resin (A) with a narrow molecular weight distribution can be obtained.

[0070] In addition, in the case of continuous bulk polymerization, in addition to the molecular weight distribution, the monomer composition distribution can also be controlled, and a styrene acrylic resin (A) with a narrow and more uniform monomer composition distribution can be obtained. Thereby, the low-temperature fixability, heat resistance shift, heat resistance storage stability, and charge stability can be further improved.

[0071] From the above viewpoints, the temperature of bulk polymerization is preferably 160 °C or higher, more preferably 170 °C or higher, further preferably 180 °C or higher, still further preferably 190 °C or higher, and preferably 350 °C or lower, more preferably 320 °C or lower.

[0072] In the present invention, "solution polymerization" means addition polymerization carried out under the condition that a solvent exists in the reaction system. The generated polymer may be soluble in the solvent or may precipitate without being soluble in the solvent. In solution polymerization, it is preferred to heat the raw material monomer (a) together with a polymerization initiator, a polymerization chain transfer agent, etc. in a solvent to carry out addition polymerization.

[0073] Examples of the polymerization initiator include peroxides such as di-tert-butyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile).

[0074] The addition amount of the polymerization initiator is not particularly limited, and 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).

[0075] Examples of the polymerization chain transfer agent include thiols such as 2-mercaptoethanol and 3-mercaptopropionic acid.

[0076] The addition amount of the polymerization chain transfer agent is not particularly limited, and is preferably 0.01 parts by mass or more and preferably 10 parts by mass or less relative to 100 parts by mass of the total amount of the raw material monomer (a).

[0077] In the case of solution polymerization, after the polymerization reaction is completed, the generated polymer can be separated and purified by known methods such as reprecipitation from the reaction solution and distilling off the solvent.

[0078] From the viewpoints of compounding with the polyester resin (B) constituting the polyester resin unit, improving low-temperature fixability, heat resistance shift, heat storage stability, and charge stability, the acid value of the styrene acrylic resin (A) is 40 mgKOH / g or higher, preferably 43 mgKOH / g or higher, more preferably 46 mgKOH / g or higher, still further preferably 48 mgKOH / g or higher, still further preferably 50 mgKOH / g or higher, and preferably 300 mgKOH / g or lower, more preferably 250 mgKOH / g or lower, further preferably 200 mgKOH / g or lower, still further preferably 150 mgKOH / g or lower, still further preferably 100 mgKOH / g or lower.

[0079] From the viewpoint of further improving low-temperature fixability, heat resistance to offset, heat storage stability, and charge stability, the weight-average molecular weight of the styrene-acrylic resin (A) is preferably 3,000 or more, more preferably 5,000 or more, still more preferably 7,000 or more, and preferably 200,000 or less, more preferably 100,000 or less, still more preferably 50,000 or less, still more preferably 30,000 or less, still more preferably 20,000 or less, still more preferably 10,000 or less.

[0080] The weight-average molecular weight of the styrene-acrylic resin (A) can be adjusted by the polymerization temperature and polymerization time.

[0081] From the viewpoint of further improving low-temperature fixability, heat resistance to offset, heat storage stability, and charge stability, the glass transition temperature of the styrene-acrylic resin (A) is preferably 45°C or more, more preferably 50°C or more, and preferably 120°C or less, more preferably 90°C or less, still more preferably 70°C or less, still more preferably 55°C or less.

[0082] From the viewpoint of further improving low-temperature fixability, heat resistance to offset, heat storage stability, and charge stability, the softening point of the styrene-acrylic resin (A) is preferably 90°C or more, more preferably 100°C or more, still more preferably 105°C or more, and preferably 160°C or less, more preferably 140°C or less, still more preferably 120°C or less. Among them, from the viewpoint of further improving low-temperature fixability, heat resistance to offset, heat storage stability, and charge stability, it is preferred that the glass transition temperature of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit is 50°C or more and the softening point is 105°C or more.

[0083] 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.

[0084] 〔Polyester resin (B)〕

[0085] The polyester resin (B) is a polyester resin that constitutes the polyester resin unit of the composite resin, and is preferably a condensate of an alcohol component (b-al) and a carboxylic acid component (b-ac) as raw material monomers (b). Hereinafter, the alcohol component (b-al) and the carboxylic acid component (b-ac) contained in the above polyester resin will be described.

[0086] (Alcohol component (b-al))

[0087] Examples of the alcohol component (b-al) include aromatic diols, aliphatic diols, alicyclic diols, and polyols having 3 or more hydroxyl groups.

[0088] As the aromatic diol, for example, an alkylene oxide adduct of bisphenol A [2,2-bis(4-hydroxyphenyl)propane] (hereinafter also referred to as "BPA-AO") can be cited. As BPA-AO, preferably, BPA-AO represented by the formula (I) can be cited,

[0089] [Chemical formula 1]

[0090]

[0091] [In the formula, OR 11 and R 12 O is an alkyleneoxy group, R 11 and R 12 are each independently an alkylene group having 1 or more and 4 or less carbon atoms (preferably an ethylene group or a propylene group), x and y are the average addition molar numbers of alkylene oxide 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, further preferably 2 or more, and preferably 16 or less, more preferably 8 or less, further preferably 4 or less.].

[0092] 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, polyoxypropylene(6)-2,2-bis(4-hydroxyphenyl)propane, and the like.

[0093] The numerical values in the parentheses above correspond to the average value of the sum of x and y in the above formula (I).

[0094] As BPA-AO, preferably, an adduct of propylene oxide with bisphenol A (hereinafter also referred to as "BPA-PO"), an adduct of ethylene oxide with bisphenol A (hereinafter also referred to as "BPA-EO"). These BPA-AOs can be used singly or in combination of two or more.

[0095] The aliphatic diol preferably has 2 or more carbon atoms, and preferably 18 or less, more preferably 14 or less, further preferably 10 or less, and further preferably 6 or less.

[0096] Examples of the aliphatic diol 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.

[0097] As the alicyclic diol, examples thereof include 1,4 - cyclohexanedimethanol, hydrogenated bisphenol A, and an adduct of hydrogenated bisphenol A and an alkylene oxide having 2 to 4 carbon atoms (average addition mole number: 2 to 12).

[0098] As the polyol having three or more hydroxyl groups, examples thereof include sorbitol, 1,2,3,6 - hexanetetraol, 1,4 - anhydro - sorbitol, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4 - butanetriol, 1,2,5 - pentanetriol, glycerol, 2 - methyl - glycerol, 2 - methyl - 1,2,4 - butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5 - tris(hydroxymethyl)benzene.

[0099] It should be noted that from the viewpoint of adjusting the molecular weight and softening point of the resin, the alcohol component (b - al) may contain a monohydric alcohol.

[0100] These alcohol components may be used alone or in combination of two or more.

[0101] Among these, the alcohol component (b - al) preferably contains at least one selected from aromatic diols and aliphatic diols having 2 to 18 carbon atoms, more preferably contains at least one selected from alkylene oxide adducts of bisphenol A, ethylene glycol, 1,2 - propylene glycol, 1,3 - propylene glycol, and neopentyl glycol, and further preferably contains an alkylene oxide adduct of bisphenol A (BPA - AO).

[0102] In the alcohol component (b - al), the amount of BPA - AO is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, still further preferably 98 mol% or more, and is 100 mol% or less, further preferably 100 mol%.

[0103] (Carboxylic acid component (b - ac))

[0104] As the carboxylic acid component (b - ac), examples thereof include dicarboxylic acid compounds and polycarboxylic acid compounds having three or more carboxyl groups.

[0105] As the dicarboxylic acid compounds, examples thereof include aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and alicyclic dicarboxylic acid compounds.

[0106] The dicarboxylic acid compounds preferably have 2 or more carbon atoms, more preferably 3 or more carbon atoms, and preferably 30 or less carbon atoms, more preferably 20 or less carbon atoms.

[0107] As the aromatic dicarboxylic acid compounds, examples thereof include phthalic acid, isophthalic acid, and terephthalic acid. Among these, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred.

[0108] As aliphatic dicarboxylic acid compounds, for example, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, pentenedioic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, azelaic acid, and succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms can be mentioned.

[0109] As succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms, 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, isooctyl succinic acid, etc. can be mentioned.

[0110] As alicyclic dicarboxylic acid compounds, for example, cyclohexanedicarboxylic acid can be mentioned.

[0111] As polycarboxylic acid compounds having 3 or more carboxylic acid groups, for example, 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid can be mentioned.

[0112] Among these, the carboxylic acid component ( b-ac ) preferably contains one or more selected from aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and polycarboxylic acid compounds having 3 or more carboxylic acid groups, more preferably contains one or more selected from terephthalic acid, isophthalic acid, maleic acid, fumaric acid, alkenyl succinic acid, and trimellitic acid, further preferably contains one or more selected from terephthalic acid, isophthalic acid, fumaric acid, and trimellitic acid, and further preferably contains one or more aromatic dicarboxylic acid compounds selected from terephthalic acid and isophthalic acid.

[0113] In the carboxylic acid component ( b-ac ), the amount of the aromatic dicarboxylic acid compound is preferably 50 mol% or more, more preferably 60 mol% or more, further preferably 70 mol% or more, further preferably 90 mol% or more, further preferably 95 mol% or more, and is 100 mol% or less, and further preferably 100 mol%.

[0114] It should be noted that from the viewpoint of controlling the degree of polymerization of the resin, the carboxylic acid component ( b-ac ) may appropriately contain polycarboxylic acid compounds having 3 or more carboxylic acid groups.

[0115] With respect to the total amount of the raw material monomers ( b ) of the polyester resin ( B ), polycarboxylic acid compounds having 3 or more carboxylic acid groups can be used in an amount of preferably 0.2% by mass or more and 30% by mass or less, more preferably 0.5% by mass or more and 20% by mass or less.

[0116] 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 more, more preferably 0.8 or more, further preferably 0.9 or more, still further preferably 1.0 or more, and is preferably 1.3 or less, more preferably 1.2 or less.

[0117] (Manufacture of Resin (B))

[0118] Resin (B) is preferably manufactured, for example, by a polycondensation reaction of a 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, heat resistance offset, heat storage stability, and charge stability, this polycondensation reaction is more preferably carried out by the following Step I'.

[0119] Step I': A step of polymerizing the raw material monomer (b) in an independent polymerization system different from the polymerization system of the raw material monomer (a) of the styrene acrylic resin (A) that constitutes the styrene acrylic resin unit to obtain a polyester resin (B) in the absence of the styrene acrylic resin (A) that constitutes the styrene acrylic resin unit.

[0120] In the polycondensation reaction in Step I', the polycondensation can be carried out using the following substances as needed: Esterification catalysts such as tin(II) bis(2-ethylhexanoate), dibutyltin oxide, and bis(triethanolamine) diisopropyl titanate, in an amount of 0.01 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the total amount of the raw material monomer (b); Esterification co-catalysts such as gallic acid (the same as 3,4,5-trihydroxybenzoic acid), in an amount of 0.001 parts by mass or more and 0.5 parts by mass or less relative to 100 parts by mass of the total amount of the raw material monomer (b).

[0121] In addition, when a monomer having an unsaturated bond such as fumaric acid is used in the polycondensation reaction in Step I', a radical inhibitor is preferably used in an amount of 0.001 parts by mass or more and 0.5 parts by mass or less relative to 100 parts by mass of the total amount of the raw material monomer (b) as needed. Examples of the radical inhibitor include 4-tert-butylcatechol.

[0122] The temperature of the polycondensation reaction in Step I' is preferably 120°C or more, more preferably 160°C or more, further preferably 180°C or more, and is preferably 260°C or less, more preferably 240°C or less. It should be noted that the polycondensation reaction can be carried out in an inert gas atmosphere.

[0123] The softening point of the polyester resin (B) is preferably 80°C or higher, more preferably 90°C or higher, still more preferably 100°C or higher, and preferably 140°C or lower, more preferably 130°C or lower, still more preferably 120°C or lower.

[0124] The glass transition temperature of the polyester resin (B) is preferably 50°C or higher, more preferably 55°C or higher, still more preferably 60°C or higher, and preferably 80°C or lower, more preferably 75°C or lower, still more preferably 70°C or lower.

[0125] The acid value of the polyester resin (B) is preferably 2 mgKOH / g or higher, and preferably 30 mgKOH / g or lower, more preferably 20 mgKOH / g or lower, still more preferably 10 mgKOH / g or lower.

[0126] The hydroxyl value of the polyester resin (B) is preferably 20 mgKOH / g or higher, more preferably 30 mgKOH / g or higher, still more preferably 40 mgKOH / g or higher, and preferably 80 mgKOH / g or lower, more preferably 70 mgKOH / g or lower, still more preferably 60 mgKOH / g or lower.

[0127] 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.

[0128] [Method for producing a binder resin for toner]

[0129] The binder resin of the present invention contains a composite resin obtained by compounding a styrene-acrylic resin (A) constituting a styrene-acrylic resin unit and a polyester resin (B) constituting a polyester resin unit.

[0130] From the viewpoint of further improving low-temperature fixability, heat resistance to offset, heat storage stability, and charge stability, the method for producing the binder resin of the present invention preferably includes:

[0131] Step I: A step of polymerizing a raw material monomer (a) in a polymerization system different 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 to obtain a styrene-acrylic resin (A); and

[0132] Step II: A step of covalently bonding the styrene-acrylic resin (A) obtained in Step I to the polyester resin (B) to obtain a binder resin for toner containing the above composite resin.

[0133] The production of the styrene-acrylic resin (A) in Step I is as described above.

[0134] From the viewpoint of further improving low-temperature fixability, heat-resistant offset properties, heat-resistant storage properties, and charge stability, the method for producing the binder resin of the present invention preferably further includes the above-mentioned step I'.

[0135] The production of the polyester resin (B) in step I' is as described above.

[0136] In the case where step I' is included in the present invention, step II is preferably a step of obtaining a binder resin for a toner containing the above composite resin through a covalent bond formed by a polymer reaction of the styrene-acrylic resin (A) obtained in step I and the polyester resin (B) obtained in step I'. That is, from the viewpoint of making the composite formation sufficient and further improving low-temperature fixability, heat-resistant offset properties, heat-resistant storage properties, and charge stability, the polymerization reaction in step II is preferably a condensation reaction between the styrene-acrylic resin (A) and the polyester resin (B). Thereby, the styrene-acrylic resin (A) and the polyester resin (B) are bonded via an ester bond as a covalent bond, and thus are composite-formed. Examples of such a condensation reaction 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).

[0137] In step II, from the viewpoint of making the composite formation sufficient and further improving low-temperature fixability, heat-resistant offset properties, heat-resistant storage properties, and charge stability, the composite formation of the styrene-acrylic resin (A) and the polyester resin (B) is preferably carried out through the formation of a covalent bond via a compound (hereinafter, also referred to as "bifunctional reactive compound") that can react with any one of the raw material monomers (a) constituting these resins (A) and the raw material monomers (b) constituting these resins (B). That is, step II is preferably a step of obtaining a binder resin for a toner containing the above composite resin through the formation of a covalent bond via a structural unit derived from a bifunctional reactive compound contained in either the styrene-acrylic resin (A) or the polyester resin (B); more preferably, it is a step of obtaining a binder resin for a toner containing the above composite resin through the formation of a covalent bond via a structural unit derived from a bifunctional reactive compound contained in the styrene-acrylic resin (A) by a polymer reaction of the styrene-acrylic resin (A) and the polyester resin (B).

[0138] The bifunctional reactive compound is preferably a compound that can react with any one 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-formed through the formation of an ester bond formed by a condensation reaction between the styrene-acrylic resin (A) and the polyester resin (B). Examples thereof include compounds represented by the following general formulas (II-1) and (II-2).

[0139] [Chemical Formula 2]

[0140]

[0141] [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 optionally have a substituent; or a halogen atom, and they may also 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 -OR 5 (R 4 and R 5 represent a hydrogen atom or a lower alkyl group which may optionally have a substituent).)

[0142] [Chemical Formula 3]

[0143]

[0144] [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 optionally have a substituent; or a halogen atom, and they may also 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.)

[0145] Herein, these bireactive compounds are preferably reactive with any one of the raw material monomers of the styrene acrylic resin (A) and the polyester resin (B), but in the case where there are two or more kinds of raw material monomers of the styrene acrylic resin (A) and the polyester resin (B) respectively, it is sufficient to be reactive with at least one of them.)

[0146] In the general formulas (II-1), (II-2), and (III-1) to (III-3), among the groups represented by R 21 to R 23 and R 31 to R 33 , specific examples or preferred forms of the alkyl group, alkoxy group, aryl group, vinyl group and halogen atom are as described below.)

[0147] As the alkyl group, a linear or branched alkyl group having 1 or more and 6 or less carbon atoms is preferred, and an alkyl group having 1 or more and 4 or less carbon atoms is more preferred. For example, methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl can be cited. These alkyl groups are optionally substituted with a phenyl group, a naphthyl group, a hydroxyl group, etc.)

[0148] As the alkoxy group, for example, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, tert-butoxy group can be mentioned, and these groups are optionally substituted with a hydroxyl group, a carboxyl group or the like.

[0149] As the aryl group, for example, phenyl group, benzyl group, naphthyl group can be mentioned, and these groups are optionally substituted with a methyl group, an ethyl group, a methoxy group, an ethoxy group, a carboxyl group, a hydroxyl group or the like.

[0150] The vinyl group is optionally substituted with a hydroxyl group, a phenyl group, an alkyl group, an alkoxy group, a carboxyl group.

[0151] As the halogen atom, for example, fluorine atom, chlorine atom, bromine atom, iodine atom can be mentioned, and chlorine atom and bromine atom are preferred.

[0152] R 4 and R 5 The lower alkyl group represented by preferably has 1 or more and 4 or less carbon atoms, and methyl group, ethyl group can be mentioned, and these groups are optionally substituted with a hydroxyl group or the like.

[0153] In the case where X is a carboxyl group in the general formula (II-2), as the compound represented by the general formula (II-2), the ethylenically unsaturated monocarboxylic acid compounds represented by the following general formulas (IV-1) to (IV-3) can be mentioned.

[0154] [Chemical formula 4]

[0155]

[0156] [In the formula, R 41 and R 42 represent the same as R 21 to R 23 : a hydrogen atom; an alkyl group, an aryl group or a vinyl group optionally having a substituent; or a halogen atom. R 43 and R 44 are the same or different and represent the same as R1] 21 to R 23 : an alkyl group, an aryl group or a vinyl group optionally having a substituent; or a halogen atom. A is the same as above. ]]

[0157] [[ID=<<47]]As specific examples of the ethylenically unsaturated monocarboxylic acid compounds represented by the general formulas (IV-1) to (IV-3), acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, and their lower alkyl esters and acid anhydrides can be mentioned.

[0158] In the case where X and Y are carboxyl groups in the general formula (II-1), as the compound represented by the general formula (II-1), the ethylenically unsaturated dicarboxylic acid compounds represented by the following general formulas (V-1) and (V-2) can be mentioned.

[0159] [Chemical formula 5]

[0160]

[0161] [wherein, R 51 and R 52 represent the same as R 21 to R 23 : a hydrogen atom; an alkyl group, an aryl group or a vinyl group which may optionally have a substituent; or a halogen atom. A and B are the same as above. ]]

[0162] Specific examples of the ethylenically unsaturated dicarboxylic acid compound represented by the general formulas (V-1) and (V-2) include maleic acid, fumaric acid, itaconic acid, mesaconic acid, citraconic acid, and their lower alkyl esters and acid anhydrides.

[0163] When X is a hydroxyl group in the general formula (II-2), examples of the compound represented by the general formula (II-2) preferably include ethylenically unsaturated monohydric alcohols represented by the following general formulas (VI-1) to (VI-3).

[0164] [Chemical formula 6]

[0165]

[0166] [wherein, R 61 to R 64 represent the same hydrogen atom, an alkyl group or an aryl group which may optionally have a substituent as R 21 to R 23 . A is the same as above. ]]

[0167] Specific examples of the ethylenically unsaturated monohydric alcohol represented by the general formulas (VI-1) to (VI-3) include 2-vinylphenol, 4-vinylphenol, 4-(1-methylethenyl)phenol, 2-allylphenol, 4-allylphenol, 2-hydroxyethyl (meth)acrylate, 2-hydroxyethylhexyl (meth)acrylate.

[0168] When X and Y are hydroxyl groups in the general formula (II-1), examples of the compound represented by the general formula (II-1) preferably include ethylenically unsaturated dihydric alcohols represented by the following general formulas (VII-1) and (VII-2).

[0169] [Chemical formula 7]

[0170]

[0171] [wherein, R 71 and R 72 represent the same as R 21 to R 23 : a hydrogen atom; an alkyl group, an aryl group or a vinyl group which may optionally have a substituent; or a halogen atom. A and B are the same as above. ]]

[0172] As a bis-reactive compound, from the viewpoints of making the compounding sufficient and further improving low-temperature fixability, heat resistance offset, heat storage stability, and charge stability, an ethylenically unsaturated monocarboxylic acid compound is preferred, and acrylic acid is more preferred.

[0173] The bis-reactive compound is preferably introduced into the polymer backbone as a raw material monomer of either the styrene-acrylic resin (A) or the polyester resin (B) before compounding, and then compounded with the other resin via the bis-reactive compound. From the viewpoint of making the compounding sufficient, it is more preferably introduced into the polymer backbone as the raw material monomer (a) of the styrene-acrylic resin (A) before compounding, and then compounded with the polyester resin (B) via the bis-reactive compound. When the raw material monomer (a) of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit contains an ethylenically unsaturated monocarboxylic acid compound as the bis-reactive compound, the compounding is carried out via an ester bond formed by a condensation reaction between the carboxyl group introduced into the polymer backbone due to the styrene-acrylic resin (A) containing a structural unit derived from the ethylenically unsaturated monocarboxylic acid compound and the hydroxyl group of the polyester resin (B).

[0174] When the total amount of the raw material monomer (a) of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit is set to 100% by mass, the amount of the bis-reactive compound 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, further preferably 3% by mass or more, further preferably 5% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, further preferably 30% by mass or less, further preferably 25% by mass or less, further preferably 20% by mass or less, further preferably 15% by mass or less, further preferably 10% by mass or less. That is, with respect to 100 parts by mass of the total amount of the raw material monomer (a), the amount of the bis-reactive compound is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, further preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and preferably 40 parts by mass or less, more preferably 35 parts by mass or less, further preferably 30 parts by mass or less, further preferably 25 parts by mass or less, further preferably 20 parts by mass or less, further preferably 15 parts by mass or less, further preferably 10 parts by mass or less.

[0175] From the viewpoints of improving the dispersibility of the styrene-acrylic resin unit, further improving the low-temperature fixability, heat resistance shift property, heat-resistant storage property, and charge stability, 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 the raw material monomers (b) constituting the polyester resin unit to the total amount of the 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 still more preferably 70 / 30 or more and 90 / 10 or less.

[0176] In the case of performing Step II by a polymer reaction, the method is not particularly limited as long as it is a method capable of forming a covalent bond, and a method of heating, melting, and mixing the styrene-acrylic resin (A) and the polyester resin (B) is preferred.

[0177] The temperature during the polymer reaction in Step II is preferably 100°C or higher, more preferably 130°C or higher, still more preferably 150°C or higher, and preferably 250°C or lower, more preferably 230°C or lower, and still more preferably 200°C or lower.

[0178] Regarding the polymer reaction in Step II, from the viewpoint of reactivity, it can be carried out under pressure or reduced pressure, and from the viewpoint of ease of reaction, it is preferably carried out at normal pressure.

[0179] In addition, the reaction time of the polymer reaction can be appropriately changed according to the reaction temperature, etc., and is preferably 1 hour or longer, and preferably 24 hours or shorter, more preferably 12 hours or shorter, and still more preferably 6 hours or shorter.

[0180] From the viewpoints of further improving the low-temperature fixability, heat resistance shift property, heat-resistant storage property, and charge stability, the content of the composite resin in the adhesive resin of the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and is 100% by mass or less, and still more preferably 100% by mass or less.

[0181] The softening point of the adhesive resin of the present invention is preferably 70°C or higher, more preferably 85°C or higher, still more preferably 100°C or higher, still more preferably 110°C or higher, and preferably 150°C or lower, more preferably 140°C or lower, still more preferably 130°C or lower, and still more preferably 120°C or lower.

[0182] 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 further preferably 65°C or lower.

[0183] The acid value of the binder resin of the present invention is preferably 50 mgKOH / g or lower, more preferably 40 mgKOH / g or lower, further preferably 35 mgKOH / g or lower, and further preferably 30 mgKOH / g or lower. On the other hand, the acid value of the binder resin of the present invention is preferably 2 mgKOH / g or higher, more preferably 8 mgKOH / g or higher, further preferably 14 mgKOH / g or higher, and further preferably 20 mgKOH / g or higher.

[0184] In order to set the softening point, glass transition temperature, and acid value of the binder resin of the present invention within these ranges, it can be easily achieved by adjusting the types and amounts of raw material monomers, the dose of free radical generation, the dose of catalyst, etc., or by selecting reaction conditions.

[0185] The binder resin of the present invention can be used alone or in combination of two or more.

[0186] As an example of using two or more binder resins of the present invention in combination, there is a case of using two binder resins with different softening points. The difference in softening point between the low-softening-point binder resin and the high-softening-point resin is preferably 5°C or higher, more preferably 7°C or higher, further preferably 10°C or higher, and preferably 40°C or lower, more preferably 30°C or lower, and further preferably 20°C or lower. [[ID=×]] [[ID=×]]

[0187] When using a low-softening-point binder resin and a high-softening-point resin in combination, the mixing ratio of the low-softening-point binder resin to the high-softening-point binder resin (low-softening-point binder resin / high-softening-point binder resin) is preferably 10 / 90 or higher and 90 / 10 or lower, more preferably 20 / 80 or higher and 80 / 20 or lower, and further preferably 30 / 70 or higher and 70 / 30 or lower.

[0188] [Toner for electrostatic image development]

[0189] The toner of the present invention contains the above-mentioned binder resin.

[0190] In the toner, the content of the above-mentioned binder resin is preferably 80% by mass or higher, more preferably 90% by mass or higher, and 100% by mass or lower.

[0191] The toner contains, for example, toner particles and external additives.

[0192] The toner particles preferably contain the above-mentioned binder resin.

[0193] Further, 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. Among these, the toner particles preferably contain a colorant.

[0194] <Colorant>

[0195] The colorant may be either a pigment or a dye.

[0196] Examples of the colorant include various carbon blacks produced by the thermal cracking method, carbon black method, acetylene black method, channel carbon black method, lamp black method, etc.; grafted carbon black with the surface of carbon black coated with resin; aniline black dye; 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.

[0197] From the viewpoint of improving the image density of the toner, the content of the colorant is preferably 1 part by mass or more and 15 parts by mass or less, more preferably 2 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the binder resin.

[0198] <Charge Control Agent>

[0199] 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.

[0200] One or more of these charge control agents may be used.

[0201] Examples of the positively chargeable charge control agent include aniline black dye, triphenylmethane-based dyes containing a tertiary amine as a side chain, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and styrene-acrylic resins.

[0202] Examples of aniline black dyes include "Nigrosine Base EX", "OIL BLACK BS", "OIL BLACK SO", "BONTRON N-01", "BONTRON N-07", "BONTRON N-11" (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 KASEI KOGYO CO., LTD.). Examples of styrene-acrylic resins include "FCA-701PT" (manufactured by FUJIKURA KASEI CO., LTD.).

[0203] Among them, BONTRON N-07 can be preferably used.

[0204] Specific examples of the negatively charged charge control agent include metal-containing azo dyes, metal compounds of diphenylglycolic acid compounds, metal compounds of salicylic acid compounds, copper phthalocyanine dyes, quaternary ammonium salts, nitroimidazole derivatives, and organometallic compounds.

[0205] Examples of metal-containing azo dyes include "VALIFAST BLACK 3804" and "BONTRON S-31" (both manufactured by ORIENT CHEMICAL INDUSTRIES LTD.), "T-77" (manufactured by Hodogaya Chemical Co., Ltd.), "BONTRON S-32", "BONTRON S-34", "BONTRON S-36" (all manufactured by ORIENT CHEMICAL INDUSTRIES LTD.), and "Aizen Spilon Black TRH" (manufactured by Hodogaya Chemical Co., Ltd.). Examples of metal compounds of salicylic acid compounds include "BONTRONE-81", "BONTRONE-82", "BONTRONE-84", and "BONTRONE-85" (all manufactured by ORIENT CHEMICAL INDUSTRIES LTD.). Examples of quaternary ammonium salts include "COPY CHARGE NX VP434" (manufactured by Hoechst). Examples of organometallic compounds include "TN105" (manufactured by Hodogaya Chemical Co., Ltd.).

[0206] Among them, BONTRONE-81, BONTRONS-34, T-77, and Aizen Spilon Black TRH can be preferably used.

[0207] With respect to 100 parts by mass of the binder resin, the content of the charge control agent is preferably 0.1 part by mass or more and 8 parts by mass or less, more preferably 0.2 part by mass or more and 5 parts by mass or less.

[0208] <Wax>

[0209] The toner of the present invention preferably contains waxes such as polyolefins and paraffin wax as anti-offset agents.

[0210] With respect to 100 parts by mass of the binder resin, the content of the wax is preferably 1 part by mass or more and 5 parts by mass or less. Here, examples of the polyolefin include polyethylene, polypropylene, etc., and a polyolefin having a lower molecular weight is preferred, particularly a polyolefin having a molecular weight of 3,000 or more and 15,000 or less based on the vapor permeation method. In addition, a polyolefin having a softening point of 70°C or more and 150°C or less, particularly 120°C or more and 150°C or less based on the ring and ball method, is preferred.

[0211] <Other Additives>

[0212] As other additives, the toner particles may also appropriately contain additives such as magnetic powder, fluidity improver, conductivity regulator, fibrous material and other reinforcing fillers, antioxidant, anti-aging agent, cleaning property improver, etc.

[0213] In the toner of the present invention, the content of the toner particles is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and is 100% by mass or less, preferably 99% by mass or less.

[0214] The volume median diameter (D 50 ) of the toner particles is preferably 2 μm or more, more preferably 3 μm or more, further preferably 5 μm or more, and is preferably 20 μm or less, more preferably 15 μm or less, further preferably 10 μm or less. In the present specification, the so-called volume median diameter (D 50 ) means the particle diameter at which the cumulative volume frequency calculated by volume fraction becomes 50% when calculated from the smaller particle diameter side.

[0215] <External Additives>

[0216] In the toner of the present invention, in order to improve fluidity, the surface of toner particles can be treated with a property modifier such as an external additive, so that the toner contains, for example, toner particles and an external additive. Examples of the external additive include fine particles of inorganic materials such as silica, alumina, titanium dioxide, zirconium oxide, tin oxide, and zinc oxide; and organic fine particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles. One or more of these can be used. Among these external additives, silica is preferred, and hydrophobic silica treated with a hydrophobizing agent is more preferred.

[0217] Examples of the hydrophobizing agent include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), and methyltriethoxysilane. Among these, hexamethyldisilazane is preferred.

[0218] In the case of surface-treating toner particles with an external additive, from the viewpoints of the chargeability and fluidity of the toner, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.08 parts by mass or more, still 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, still more preferably 2 parts by mass or less, relative to 100 parts by mass of the toner particles.

[0219] [Manufacturing method of toner]

[0220] The toner of the present invention can be a toner obtained by any known method such as a melt-kneading method, an emulsion inversion method, a suspension polymerization method, or an emulsion aggregation method. From the viewpoints of productivity and dispersibility of the colorant, a pulverized toner obtained by the melt-kneading method is preferred.

[0221] In the melt-kneading method, after uniformly dispersing the above-mentioned binder resin, colorant, and, if necessary, property modifier, melt-kneading, cooling, pulverizing, and classifying are performed by known methods, whereby a toner having a volume median diameter (D 50 ) of 5 μm or more and 15 μm or less can be obtained.

[0222] The toner of the present invention is used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, etc. This toner can be used as a non-magnetic one-component developer, or can be directly mixed with a carrier such as an iron oxide-based carrier, a regular spherical iron oxide-based carrier, or a ferrite-based carrier, or mixed with a substance obtained by coating a carrier with a resin or the like to be used as a dry two-component developer.

[0223] Regarding the above embodiments, the present invention further discloses the following binder resin for toner, toner for electrostatic image development, and manufacturing method of the binder resin for toner.

[0224] <1> A binder resin for toner, which is a binder resin for toner containing a composite resin formed by covalently bonding a styrene acrylic resin unit and a polyester resin unit.

[0225] The acid value of the styrene acrylic resin (A) constituting the above-mentioned styrene acrylic resin unit is 40 mgKOH / g or more.

[0226] <2> The binder resin for toner according to the above <1>, wherein the above composite resin is a resin formed by forming a covalent bond through a polymer reaction of the above styrene acrylic resin (A) and the polyester resin (B) constituting the above polyester resin unit.

[0227] <3> The binder resin for toner according to the above <2>, wherein the polymerization systems of the above styrene acrylic resin (A) and the above polyester resin (B) are independent reaction systems.

[0228] <4> The binder resin for toner according to any one of the above <1> to <3>, wherein the above styrene acrylic resin (A) is an addition polymer of a raw material monomer (a) containing a styrene-based compound and a (meth)acrylic acid-based monomer.

[0229] <5> The binder resin for toner according to any one of the above <1> to <4>, wherein the above styrene acrylic resin (A) is polymerized through an independent polymerization system different from the polymerization system of the raw material monomer (b) constituting the above polyester resin (B) in the absence of the above polyester resin (B) constituting the polyester resin unit.

[0230] <6> The binder resin for toner according to any one of the above <1> to <5>, wherein the above styrene acrylic resin (A) is preferably formed by bulk polymerization or solution polymerization, and more preferably formed by bulk polymerization.

[0231] <7> The binder resin for toner according to the above <6>, wherein the bulk polymerization of the above styrene acrylic resin (A) is a polymerization under solvent-free conditions.

[0232] <8> The binder resin for toner according to the above <6> or <7>, wherein when the total amount of the raw material monomer (a) of the styrene acrylic resin (A) is set to 100% by mass, the concentration of the radical generator in the bulk polymerization of the above styrene acrylic resin (A) is preferably 7% by mass or less, more preferably 5% by mass or less, further preferably 2% by mass or less, further preferably 1% by mass or less, further preferably 0.5% by mass or less, and further preferably 0% by mass with respect to the total amount of the raw material monomer (a).

[0233] <9> The binder resin for toner according to <6> or <7> above, wherein the bulk polymerization of the styrene acrylic resin (A) is carried out without a catalyst.

[0234] <10> The binder resin for toner according to any one of <6> to <9> above, wherein the temperature of the bulk polymerization of the styrene acrylic resin (A) is preferably 160 °C or higher, more preferably 170 °C or higher, further preferably 180 °C or higher, further preferably 190 °C or higher, and preferably 350 °C or lower, more preferably 320 °C or lower.

[0235] <11> The binder resin for toner according to any one of <1> to <10> above, wherein the acid value of the styrene acrylic resin (A) is preferably 43 mgKOH / g or higher, more preferably 46 mgKOH / g or higher, further preferably 48 mgKOH / g or higher, further preferably 50 mgKOH / g or higher, and preferably 300 mgKOH / g or lower, more preferably 250 mgKOH / g or lower, further preferably 200 mgKOH / g or lower, further preferably 150 mgKOH / g or lower, further preferably 100 mgKOH / g or lower.

[0236] <12> The binder resin for toner according to any one of <1> to <11> above, wherein the weight average molecular weight of the styrene acrylic resin (A) is preferably 3,000 or higher, more preferably 5,000 or higher, further preferably 7,000 or higher, and preferably 200,000 or lower, more preferably 100,000 or lower, further preferably 50,000 or lower, further preferably 30,000 or lower, further preferably 20,000 or lower, further preferably 10,000 or lower.

[0237] <13> The binder resin for toner according to any one of <1> to <12> above, wherein the glass transition temperature of the styrene acrylic resin (A) is preferably 45 °C or higher, more preferably 50 °C or higher, and preferably 120 °C or lower, more preferably 90 °C or lower, further preferably 70 °C or lower, further preferably 55 °C or lower.

[0238] <14> The binder resin for toner according to any one of <1> to <13> above, wherein the softening point of the styrene acrylic resin (A) is preferably 90 °C or higher, more preferably 100 °C or higher, further preferably 105 °C or higher, and preferably 160 °C or lower, more preferably 140 °C or lower, further preferably 120 °C or lower.

[0239] <15> The binder resin for toner according to any one of <1> to <14> above, wherein the glass transition temperature of the styrene acrylic resin (A) is 50°C or higher and the softening point is 105°C or higher.

[0240] <16> The binder resin for toner according to any one of <2> to <15> above, wherein the polyester resin (B) is a polyester resin which is a condensate of an alcohol component (b-al) and a carboxylic acid component (b-ac) as raw material monomers (b).

[0241] <17> The binder resin for toner according to any one of <2> to <16> above, wherein the polyester resin (B) is polymerized from the raw material monomer (b) in an independent polymerization system different from the polymerization system of the raw material monomer (a) for forming 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.

[0242] <18> The binder resin for toner according to any one of <2> to <17> above, wherein the hydroxyl value of the polyester resin (B) is preferably 20 mgKOH / g or higher, more preferably 30 mgKOH / g or higher, still more preferably 40 mgKOH / g or higher, and preferably 80 mgKOH / g or lower, more preferably 70 mgKOH / g or lower, still more preferably 60 mgKOH / g or lower.

[0243] <19> The binder resin for toner according to any one of <1> to <18> above, wherein the softening point is preferably 70°C or higher, more preferably 85°C or higher, still more preferably 100°C or higher, still more preferably 110°C or higher, and preferably 150°C or lower, more preferably 140°C or lower, still more preferably 130°C or lower, still more preferably 120°C or lower.

[0244] <20> The binder resin for toner according to any one of <1> to <19> above, wherein the glass transition temperature is preferably 50°C or higher, more preferably 53°C or higher, and preferably 80°C or lower, more preferably 70°C or lower, still more preferably 65°C or lower.

[0245] <21> The binder resin for toner according to any one of <1> to <20> above, wherein the acid value is preferably 50 mgKOH / g or lower, more preferably 40 mgKOH / g or lower, still more preferably 35 mgKOH / g or lower, still more preferably 30 mgKOH / g or lower.

[0246] <22> The acid value of the binder resin for toner according to any one of <1> to <21> above is preferably 2 mgKOH / g or more, more preferably 8 mgKOH / g or more, further preferably 14 mgKOH / g or more, and still further preferably 20 mgKOH / g or more.

[0247] <23> An electrostatic image developing toner containing the binder resin for toner according to any one of <1> to <22> above.

[0248] <24> A method for producing a binder resin for toner, which is 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, the production method comprising:

[0249] Step I: A step of polymerizing a raw material monomer (a) in an independent polymerization system different 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 to obtain a styrene-acrylic resin (A); and

[0250] 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 above composite resin.

[0251] The acid value of the above styrene-acrylic resin (A) is 40 mgKOH / g or more.

[0252] <25> According to the method for producing a binder resin for toner according to <24> above, the polymerization of the raw material monomer (a) in Step I is preferably bulk polymerization or solution polymerization, and more preferably bulk polymerization.

[0253] <26> According to the method for producing a binder resin for toner according to <24> or <25> above, the method further includes the following Step I',

[0254] Step I': A step of polymerizing a raw material monomer (b) in an independent polymerization system different from 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 to obtain a polyester resin (B).

[0255] <27> According to the method for producing a binder resin for toner according to <26> above, Step II is a step of bonding via a covalent bond formed by a polymer reaction between the styrene-acrylic resin (A) obtained in Step I and the polyester resin (B) obtained in Step I' to obtain a binder resin for toner containing the above composite resin.

[0256] <28> The method for producing a binder resin for toner according to <27> above, wherein the polymer reaction in Step II is a condensation reaction.

[0257] <29> The method for producing a binder resin for toner according to any one of <24> to <28> above, wherein in Step II, the compounding of the styrene-acrylic resin (A) and the polyester resin (B) is carried out by forming a covalent bond via a double-reactive compound capable of reacting with either the raw material monomer (a) constituting the styrene-acrylic resin (A) or the raw material monomer (b) constituting the polyester resin (B).

[0258] <30> The method for producing a binder resin for toner according to any one of <24> to <29> above, wherein Step II is preferably a step of forming a covalent bond via a structural unit derived from a double-reactive compound contained in either the styrene-acrylic resin (A) or the polyester resin (B) to obtain a binder resin for toner containing the above composite resin, and more preferably a step of forming a covalent bond via a structural unit derived from a double-reactive compound contained in the styrene-acrylic resin (A) by a polymer reaction of the styrene-acrylic resin (A) and the polyester resin (B) to obtain a binder resin for toner containing the above composite resin.

[0259] <31> The method for producing a binder resin for toner according to <29> or <30> above, wherein when the total amount of the raw material monomer (a) of the styrene-acrylic resin (A) constituting the styrene-acrylic resin unit is set to 100% by mass, the amount of the above double-reactive compound is preferably 0.5% by mass or more, more preferably 1% by mass or more, further preferably 3% by mass or more, further preferably 5% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, further preferably 30% by mass or less, further preferably 25% by mass or less, further preferably 20% by mass or less, further preferably 15% by mass or less, further preferably 10% by mass or less.

[0260] <32>According to the method for producing a binder resin for toner according to any one of <24> to <31> above, 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 total mass of the raw material monomers (b) constituting the polyester resin unit to the total mass of the 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 still more preferably 70 / 30 or more and 90 / 10 or less.

[0261] <33>A binder resin for toner, which 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.

[0262] The styrene acrylic resin (A) constituting the styrene acrylic resin unit is formed by bulk polymerization.

[0263] The acid value of the styrene acrylic resin (A) is 40 mgKOH / g or more.

[0264] <34>A binder resin for toner, which 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.

[0265] A covalent bond is formed by a polymer reaction of the styrene acrylic resin (A) constituting the styrene acrylic resin unit and the polyester resin (B) constituting the polyester resin unit.

[0266] The styrene acrylic resin (A) is formed by bulk polymerization.

[0267] The acid value of the styrene acrylic resin (A) is 40 mgKOH / g or more.

[0268] Examples

[0269] [Measurement]

[0270] [Acid value and hydroxyl value of resin]

[0271] The acid value and hydroxyl value of the resin were measured based on the method of JIS K0070:1992. Among them, in this method, only the measurement solvent was changed from a mixed solvent of ethanol and ether to the following solvents: in the measurement of the acid value, it was changed to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)); in the measurement of the hydroxyl group, it was changed to tetrahydrofuran.

[0272] 〔Weight-average molecular weight of the resin〕

[0273] The molecular weight distribution is measured by gel permeation chromatography (GPC) obtained by the following method, and the weight-average molecular weight is determined.

[0274] (1) Preparation of the sample solution

[0275] Dissolve the sample in tetrahydrofuran so that the concentration becomes 0.5 g / 100 mL. Next, filter this solution using a fluororesin filter "FP-200" (manufactured by Sumitomo Electric Industries, Ltd.) with a pore size of 2 μm to remove insoluble components, and prepare a sample solution.

[0276] (2) Measurement of the weight-average molecular weight

[0277] Using the following measuring device and analytical column, as the eluent, flow tetrahydrofuran at a flow rate of 1 mL per minute, and stabilize the column in a constant temperature bath at 40°C. Inject 100 μL of the sample solution for measurement. The molecular weight of the sample is calculated based on a standard curve prepared in advance. The standard curve at this time uses several monodisperse polystyrenes ("A-500" (Mw: 5.0×10 2 ) (manufactured by Tosoh Corporation), "A-1000" (Mw: 1.01×10 3 ) (manufactured by Tosoh Corporation), "A-2500" (Mw: 2.63×10 3 ) (manufactured by Tosoh Corporation), "A-5000" (Mw: 5.97×10 3 ) (manufactured by Tosoh Corporation), "F-1" (Mw: 1.02×10 4 ) (manufactured by Tosoh Corporation), "F-2" (Mw: 1.81×10 4 ) (manufactured by Tosoh Corporation), "F-4" (Mw: 3.97×10 4 ) (manufactured by Tosoh Corporation), "F-10" (Mw: 9.64×10 4 ) (manufactured by Tosoh Corporation), "F-20" (Mw: 1.90×10 5 ) (manufactured by Tosoh Corporation), "F-40" (Mw: 4.27×10 5 ) (manufactured by Tosoh Corporation), "F-80" (Mw: 7.06×10 5 ) (manufactured by Tosoh Corporation), "F-128" (Mw: 1.09×10 6 )) as standard samples to prepare a standard curve. The values in parentheses represent the molecular weights.

[0278] Measuring device: "HLC-8220GPC" (manufactured by Tosoh Corporation)

[0279] Analytical column: "GMHXL" + "G3000HXL" (manufactured by Tosoh Corporation)

[0280] 〔Glass transition temperature of the resin〕

[0281] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample was weighed in an aluminum pan, heated to 200 °C, and then cooled from this temperature to 0 °C at a cooling rate of 10 °C / min. Subsequently, the temperature was raised to 150 °C at a heating rate of 10 °C / min, and the temperature at the intersection of the extension of the baseline below the peak temperature of the endotherm and the tangent representing the maximum slope from the rising part of the peak to the peak apex was defined as the glass transition temperature.

[0282] 〔Softening point of resin〕

[0283] Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), while heating 1 g of the sample at a heating rate of 6 °C / min, a load of 1.96 MPa was applied through a plunger, and the sample was extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of descent of the plunger of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was defined as the softening point.

[0284] 〔Melting point of release agent〕

[0285] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), 0.02 g of the sample was weighed in an aluminum pan, heated to 200 °C, and then cooled from 200 °C to 0 °C at a cooling rate of 10 °C / min. Next, the sample was heated at a heating rate of 10 °C / min, and the heat was measured. The maximum peak temperature of the endotherm obtained was defined as the melting point.

[0286] 〔Volume median diameter (D 50 ) of toner particles〕

[0287] The volume median diameter (D 50 ) of the toner particles was measured as follows.

[0288] · Measuring device: "Coulter Multisizer (registered trademark) III" (manufactured by Beckmann Coulter, Inc.)

[0289] · Aperture: 50 μm

[0290] · Analysis software: "Coulter Multisizer (registered trademark) III version 3.51" (manufactured by Beckmann Coulter, Inc.)

[0291] · Electrolyte: "ISOTON (registered trademark) II" (manufactured by Beckmann Coulter, Inc.)

[0292] · Dispersion: Dissolve "EMULGEN (registered trademark) 109P" [polyoxyethylene lauryl ether, manufactured by Kao Corporation, HLB (hydrophilic-lipophilic balance value, Griffin method) = 13.6] in the above electrolyte to obtain a dispersion with a concentration of 5% by mass.

[0293] · Dispersion conditions: Add 10 mg of the test sample to 5 mL of the above dispersion, disperse it with an ultrasonic disperser for 1 minute, then add 25 mL of the electrolyte, and further disperse it with an ultrasonic disperser for 1 minute to prepare a sample dispersion.

[0294] · Measurement conditions: In a beaker, add the above sample dispersion to 100 mL of the above electrolyte to adjust to a concentration at which 30,000 particles can be measured for their particle size within 20 seconds, then measure 30,000 particles, and obtain the volume median diameter (D 50 ) from the resulting particle size distribution.

[0295] [Manufacture of Resin (A) and Resin (B)]

[0296] Production Examples A1 to A5, Comparative Production Example A51 (Manufacture of Resins A-1 to A-5, A-51)

[0297] Put the raw material monomers of the styrene-acrylic resin containing acrylic acid as a bireactive compound shown in Table 1 into an autoclave equipped with a stainless-steel stirrer, and polymerize the raw material monomers under pressure heating conditions (300 °C) for 2 hours. Restore to normal pressure and normal temperature to recover the precipitated styrene-acrylic resin, thereby obtaining styrene-acrylic resins A-1 to A- and A-51.

[0298] Production Example A6 (Manufacture of A-6)

[0299] Put the raw material monomers of the styrene-acrylic resin containing acrylic acid as a bireactive compound and a radical generator shown in Table 1 into a stainless-steel reaction vessel equipped with a thermometer, a stainless-steel stirrer, a downward-flow condenser equipped with a dehydrating tube, and a nitrogen inlet tube, and polymerize the raw material monomers at 150 °C for 2 hours. Restore to normal temperature to recover the precipitated styrene-acrylic resin, thereby obtaining styrene-acrylic resin A-6.

[0300] [Table 1]

[0301] Table 1

[0302]

[0303] *1: Amount of radical generator relative to the total amount of raw material monomers (a) (mass%)

[0304] Production Examples B1 to B4 (Production of Resins B-1 to B-4)

[0305] The raw material monomers of the polyester resin shown in Table 2, an esterification catalyst, and a cocatalyst were placed in a 10 L four-necked flask equipped with a thermometer, a stainless-steel stirrer, a downward-flow condenser equipped with a dehydrating tube, and a nitrogen inlet tube. After heating to 180°C in a nitrogen atmosphere, the temperature was raised to 230°C at a rate of 5°C per hour. After confirming that all the solid monomers had undergone a melting reaction, the pressure was reduced to 60 torr and dehydration condensation was carried out for 1 hour. Thereafter, the pressure was restored to atmospheric pressure, and after cooling to 160°C, the temperature was raised to 220°C, and the reaction was further carried out at 220°C for 1 hour. Then, a condensation reaction was carried out under the conditions of 220°C and 60 torr until the softening point reached the softening point shown in Table 2, to obtain Resins B-1 to B-4.

[0306] [Table 2]

[0307]

[0308] [Production of Adhesive Resin]

[0309] Examples 1-1 to 1-11 and Comparative Example 1-1 (Production of Adhesive Resins C-1 to C-11, C-51)

[0310] The combination and mixing ratio of the styrene-acrylic resin (A) and the polyester resin (B) shown in Table 3 were placed in a 10 L four-necked flask equipped with a thermometer, a stainless-steel stirrer, a downward-flow condenser equipped with a dehydrating tube, and a nitrogen inlet tube. They were heated at 180°C for 4 hours in a nitrogen atmosphere to melt and mix the styrene-acrylic resin (A) and the polyester resin (B) and carry out a condensation reaction. Thereafter, the temperature was further raised to 230°C and the reaction was carried out for 1 hour, and then the pressure was reduced to 60 torr. After confirming that the softening point of the resin reached the specified softening point shown in Table 3, the reaction was stopped to form a composite resin, and Adhesive Resins C-1 to C-11, C-51 were obtained.

[0311] [Table 3]

[0312] Table 3

[0313]

[0314] Comparative Example 1-2 (Production of Adhesive Resin C-52)

[0315] The raw material monomers of the polyester resin unit other than trimellitic anhydride shown in Table 4, acrylic acid of the bireactive compound, and an esterification catalyst and a cocatalyst were placed in a 10-L four-necked flask equipped with a thermometer, a stainless-steel stirrer, a downflow condenser equipped with a dehydrating tube, and a nitrogen inlet tube, and heated at 160 °C in a nitrogen atmosphere. A mixed solution of the raw material monomers of the styrene-acrylic resin unit and a polymerization initiator shown in Table 4 was added dropwise thereto over 1 hour. After the addition, the temperature was raised to 200 °C, and a curing reaction was carried out for 1 hour, whereby a styrene-acrylic resin was formed in the reaction system. Thereafter, the temperature was raised to 230 °C every 1 hour. After confirming that all the solid monomers had undergone a melting reaction, the pressure was reduced to 60 torr, and dehydration condensation was carried out for 1 hour. Then, trimellitic anhydride was added, and the dehydration condensation reaction was continued at 230 °C until the softening point reached the softening point shown in Table 4, thereby obtaining the adhesive resin C-52.

[0316] [Table 4]

[0317] Table 4

[0318]

[0319] *1: It means the molar fraction of each monomer when the alcohol component of the raw material monomer (b) is set to 100 mol.

[0320] *2: It means the mass fraction of each monomer when the raw material monomer (a) is set to 100 parts by mass.

[0321] *3: It means the mass fraction of each component when the raw material monomer (b) is set to 100 parts by mass.

[0322] *4: BPA-P0 means a polyoxypropylene (2.2) adduct of bisphenol A.

[0323] *5: BPA-E0 means a polyoxyethylene (2.2) adduct of bisphenol A.

[0324] [Manufacture of Toner]

[0325] Examples 2-1 to 2-11 and Comparative Examples 2-1 to 2-2

[0326] Using a Henschel mixer, 100 parts by mass in total 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 INDUSTRIES, LTD.), 5 parts by mass of the colorant “Pigment blue 15:3” (manufactured by Dainichi Seika Kogyo Co., Ltd.), and 2 parts by mass of the mold release agent “HNP-9” (paraffin wax, melting point: 80 °C, manufactured by Nippon Seiro Co., Ltd.) were thoroughly mixed. Then, using a co-rotating twin-screw extruder with a total length of the kneading section of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm, melt-kneading was carried out at a screw rotation speed of 200 r / min and a barrel set temperature of 100 °C. The supply rate of the mixture was 20 kg / h, and the average residence time was about 18 seconds. The obtained melt-kneaded product was cooled and coarsely pulverized, and then pulverized and classified using a jet mill to obtain toner particles with a volume median diameter (D 50 ) of 8 μm.

[0327] 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 mixed using a Henschel mixer at 3600 r / min for 5 minutes to perform external additive treatment, thereby obtaining a toner.

[0328] [Toner Evaluation]

[0329] [Low-temperature Fixing Property and Heat Resistance Offset Property]

[0330] Each toner was installed in a device obtained by modifying the fixing unit of the copying machine “AR-505” (manufactured by Sharp Corporation) so as to be able to fix outside the device, and a printed matter (printing area: 2 cm × 12 cm, adhesion amount: 0.5 mg / cm 2 ) was obtained in an unfixed state. Thereafter, using a fixing unit adjusted so that the total fixing pressure became 40 kgf (fixing speed 300 mm / s), while raising the temperature of the fixing roller from 80 °C to 240 °C in increments of 5 °C each time, a fixing test of the unfixed printed matter was carried out at each temperature. A cellophane tape “UNICEF CELLOPHANE” (manufactured by Mitsubishi Pencil Co., Ltd., width: 18 mm, JIS Z1522) was attached to the image portion of the obtained printed matter, and after passing it through the fixing roller set at 30 °C, the tape was peeled off. Using a reflection densitometer “RD-915” (manufactured by Gretag Macbeth), the optical reflection densities before pasting the tape and after peeling off the tape were measured, and the temperature of the fixing roller at which the ratio of the two (after peeling / before pasting × 100) first exceeded 90% was set as the minimum fixing temperature. The lower the minimum fixing temperature, the more excellent the low-temperature fixing property.

[0331] In addition, visually judge the fixed image obtained above, and set the lowest temperature of the fixing roller with thermal offset as the thermal offset temperature. It should be noted that "CopyBond SF-70NA" (manufactured by Sharp Corporation, 75 g / m 2 ) is used for the fixed paper. The higher the thermal offset temperature, the more excellent the thermal offset resistance.

[0332] The results of these are shown in Table 5.

[0333] [Heat resistance and storage stability]

[0334] Add 5 g of each toner to a 50 mL polyethylene bottle, and place it in an environment of 50 °C and 60% relative humidity for 48 hours. Then, sieve the toner through a 100 μm mesh screen, weigh the residual toner on the screen, and evaluate the heat resistance and storage stability according to the following evaluation criteria. The results are shown in Table 5.

[0335] (Evaluation criteria)

[0336] A: Residual toner is less than 0.5 g

[0337] B: Residual toner is 0.5 g or more and less than 1 g

[0338] C: Residual toner is 1 g or more

[0339] [Charge stability]

[0340] Under the conditions of 32 °C and 50% relative humidity, add 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) to a 50 mL polyethylene bottle, and mix them using a ball mill at 250 r / min. Measure the charge amount of the toner by the following method using a Q / M meter (manufactured by EPPING).

[0341] After the specified mixing time, put a specified amount of the mixture of toner and carrier into the unit attached to the Q / M meter, and attract only the toner for 90 seconds through a 32 μm mesh screen (made of stainless steel, twill weave, wire diameter: 0.0035 mm). Monitor the voltage change on the carrier generated at this time, and set the value of X = [total charge amount (μC) after 90 seconds / attracted toner amount (g)] as the charge amount (μC / g). Calculate the charge amount X after 60 seconds of mixing time 60 and the charge amount X after 600 seconds of mixing time 600 ratio (X 60 / X 600 ), and evaluate the charge stability according to the following evaluation criteria. The larger the value, the more excellent the charge stability under high temperature and high humidity. The results are shown in Table 5.

[0342] (Evaluation Criteria)

[0343] A: The ratio (X 60 / X 600 ) is 0.90 or more

[0344] B: The ratio (X 60 / X 600 ) is 0.80 or more and less than 0.90

[0345] C: The ratio (X 60 / X 600 ) is less than 0.80

[0346] [Table 5]

[0347] Table 5

[0348]

[0349] *1: Mixture of adhesive resins C-1 and C-8 (mixing ratio [C-1 / C-8] = 50 / 50)

[0350] As shown in Table 5, compared with the toner of the comparative example, the toner of the example using the adhesive resin containing the specific composite resin has a lower minimum fixing temperature and a higher thermal offset temperature. Therefore, it is known that the low-temperature fixability and heat resistance to offset are excellent, and the heat-resistant storage stability and charging stability are also excellent.

Claims

1. A toner for electrostatic image development, which contains a binder resin for toner, and the binder resin for toner contains a composite resin formed by covalently bonding a styrene-acrylic resin unit and a polyester resin unit. The acid value of the styrene-acrylic resin A constituting the styrene-acrylic resin unit is 40 mgKOH / g or more. The styrene-acrylic resin A is polymerized through an independent polymerization system different 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.

2. The toner for electrostatic image development according to claim 1, wherein, The composite resin is a resin formed by forming a covalent bond through a polymer reaction between the styrene-acrylic resin A and the polyester resin B constituting the polyester resin unit.

3. The toner for electrostatic image development according to claim 1 or 2, wherein The styrene-acrylic resin A is an addition polymer of a raw material monomer a containing a styrene compound and a (meth)acrylic monomer.

4. The toner for electrostatic image development according to claim 1 or 2, wherein, The content of the structural unit derived from the styrene compound in the styrene-acrylic resin A is 50% by mass or more and 98% by mass or less.

5. The toner for electrostatic image development according to claim 1 or 2, wherein, The styrene-acrylic resin A is formed by bulk polymerization.

6. The toner for electrostatic image development according to claim 5, wherein, The concentration of the radical generator in the bulk polymerization of the styrene-acrylic resin A is 1% by mass or less relative to the total amount of the raw material monomer a of the styrene-acrylic resin A.

7. The toner for electrostatic image development according to claim 5, wherein, The bulk polymerization of the styrene-acrylic resin A is a polymerization under solvent-free conditions.

8. The toner for electrostatic image development according to claim 5, wherein, The bulk polymerization of the styrene-acrylic resin A is a polymerization under catalyst-free conditions.

9. The toner for electrostatic image development according to claim 5, wherein, The bulk polymerization of the styrene-acrylic resin A is a polymerization under conditions of 160 °C or higher.

10. The toner for electrostatic image development according to claim 1 or 2, wherein, The weight-average molecular weight of the styrene-acrylic resin A is 3,000 or more and 200,000 or less.

11. The toner for electrostatic image development according to claim 1 or 2, wherein, The glass transition temperature of the styrene-acrylic resin A is 45 °C or more and 120 °C or less.

12. The toner for electrostatic image development according to claim 1 or 2, wherein, The softening point of the styrene-acrylic resin A is 90 °C or more and 160 °C or less.

13. The toner for electrostatic image development according to claim 1 or 2, wherein, The glass transition temperature of the styrene-acrylic resin A is 50 °C or more and the softening point is 105 °C or more.

14. The toner for electrostatic image development according to claim 1 or 2, wherein, The polyester resin B is a polyester resin that is a condensate of an alcohol component b-al and a carboxylic acid component b-ac as raw material monomers b.

15. The toner for electrostatic image development according to claim 14, wherein, The alcohol component b-al contains one or more selected from alkylene oxide adducts of bisphenol A, ethylene glycol, 1,2-propanediol, 1,3-propanediol, and neopentyl glycol.

16. The toner for electrostatic image development according to claim 14, wherein, The carboxylic acid component b-ac contains one or more selected from terephthalic acid, isophthalic acid, maleic acid, fumaric acid, alkenyl succinic acid, and trimellitic acid.

17. The toner for electrostatic image development according to claim 1 or 2, wherein, The hydroxyl value of the polyester resin B is 20 mgKOH / g or more and 80 mgKOH / g or less.

18. The toner for electrostatic image development according to claim 1 or 2, wherein, 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, that is, polyester resin B / styrene-acrylic resin A, is 30 / 70 or more and 98 / 2 or less.

19. The toner for electrostatic image development according to claim 1 or 2, wherein, The softening point of the binder resin for toner is 70 °C or more and 150 °C or less.

20. The toner for electrostatic image development according to claim 1 or 2, wherein, The glass transition temperature of the binder resin for toner is 50°C or higher and 80°C or lower.

21. The toner for electrostatic image development according to claim 1 or 2, wherein, The acid value of the binder resin for toner is 2 mgKOH / g or higher and 50 mgKOH / g or lower.

22. A method for manufacturing a toner for electrostatic image development, the toner for electrostatic image development containing a binder resin for toner, the binder resin for toner containing a composite resin formed by covalently bonding a styrene-acrylic resin unit and a polyester resin unit, the manufacturing method including: Step I: A step of polymerizing a raw material monomer a in an independent polymerization system different 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 to obtain a styrene-acrylic resin A; and Step II: A step of covalently bonding the styrene-acrylic resin A obtained in Step I to the polyester resin B to obtain a binder resin for toner containing the composite resin. The acid value of the styrene-acrylic resin A is 40 mgKOH / g or higher.

23. The method for manufacturing a toner for electrostatic image development according to claim 22, further including the following Step I': Step I': A step of polymerizing a raw material monomer b in an independent polymerization system different from 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 to obtain a polyester resin B.

24. The method for manufacturing a toner for electrostatic image development according to claim 23, wherein, Step II is a step of obtaining a binder resin for toner containing the composite resin by covalently bonding through a covalent bond formed by a polymer reaction of the styrene-acrylic resin A obtained in Step I and the polyester resin B obtained in Step I'.

25. The method for manufacturing a toner for electrostatic image development according to any one of claims 22 to 24, wherein, The polymer reaction in Step II is a condensation reaction.

26. The method for producing a toner for electrostatic image development according to any one of claims 22 to 24, wherein, The polymerization of the raw material monomer a in Step I is bulk polymerization.

27. The method for producing a toner for electrostatic image development according to any one of claims 22 to 24, wherein, Step II is a step of obtaining a binder resin for toner containing the above composite resin by forming a covalent bond through a polymer reaction of the styrene-acrylic resin A and the polyester resin B via a structural unit derived from a di-reactive compound contained in the styrene-acrylic resin A.

28. The method for manufacturing a toner for electrostatic image development according to claim 27, wherein, When the total amount of the raw material monomer a of the styrene-acrylic resin A constituting the styrene-acrylic resin unit is set to 100% by mass, the amount of the di-reactive compound is 0.5% by mass or higher and 40% by mass or lower relative to the total amount of the raw material monomer a.

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