Positively chargeable toner for developing electrostatic image, toner set, and image forming method

Abstract

Provided is a toner which has an excellent balance between low-temperature fixability and heat-resistant storability, is unlikely to generate fogging, and is capable of forming an image having excellent gloss uniformity. The present invention provides a positively charged toner for electrostatic image development, which contains colored resin particles that contain a binder resin, a colorant, a release agent, a release agent dispersant, and a charge control agent, contains a styrene acrylic resin and a polyester resin as the binder resin, and contains an ester wax as the release agent, the toner particles contain a nonionic surfactant as the release dispersant, and the mass of the nonionic surfactant present on the surfaces of the toner particles is 0.1-500 ppm with respect to the mass of the toner particles.

Description

Technical Field

[0001] This invention relates to a positively charged toner for developing electrostatic images, used in electrophotography, electrostatic recording, and electrostatic printing for developing electrostatic latent images.

[0002] Furthermore, the present invention relates to a toner set composed of positively charged toners for developing electrostatic images, and an image forming method using the toner set. Background Technology

[0003] In image forming apparatuses such as electrophotographic devices, electrostatic recording devices, and electrostatic printing devices, a toner is used to develop an electrostatic latent image formed on a photoreceptor. After the toner image is transferred to a transfer material such as paper, it is fixed by heating or other means to form a fixed image.

[0004] In such an image forming apparatus, for purposes such as reducing power consumption, reducing environmental impact, and increasing printing speed, there is a need for an electrostatic image developing toner (hereinafter referred to as "toner") that can be heat-fixed at a lower temperature.

[0005] For example, Patent Document 1 aims to provide a toner with excellent low-temperature fixing properties, heat resistance, fixing separation, and durability. It discloses a toner in which a styrene-acrylic resin is included as the binding resin in toner particles containing a binder, colorant, release agent, and plasticizer, and the average aspect ratio (Aw) of the release agent region in the cross-section of the toner particles is greater than the average aspect ratio (Ac) of the plasticizer region. In the toner invented in Patent Document 1, microcrystalline wax is used as the release agent.

[0006] Patent Document 2 aims to provide an image forming apparatus that simultaneously satisfies low-temperature fixing and environmental stability. As a toner for this image forming apparatus, it discloses a toner containing a monoester compound with a specific structure as a wax.

[0007] Patent Document 3 aims to provide a toner capable of achieving high image density and excellent electrical stability. It discloses a toner comprising a composite resin, wherein the resin constituting the binder resin contains polyester resin segments, addition polymer resin segments as addition polymers containing styrene-based compounds as raw material monomers, and structural units from two reactive monomers that covalently bond the polyester resin segments and the addition polymer resin segments. In the toner disclosed in Patent Document 3, a hydrocarbon wax is used as a release agent.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2016-206387;

[0011] Patent Document 2: Japanese Patent Application Publication No. 2021-86067;

[0012] Patent document 3: Japanese Patent Application Publication No. 2022-164798. Summary of the Invention

[0013] The problem the invention aims to solve

[0014] In toners, a good balance needs to be struck between low-temperature fixing and heat-resistant preservation. However, toners with good low-temperature fixing and heat-resistant preservation are prone to other problems such as haze.

[0015] In addition, when only hydrocarbon waxes are used as release agents, uneven gloss is likely to occur.

[0016] The purpose of this invention is to provide a toner that offers an excellent balance between low-temperature fixing and heat preservation, is less prone to producing haze, and can form images with excellent gloss uniformity.

[0017] Furthermore, the object of the present invention is to provide a toner set capable of forming multicolor images with excellent gloss uniformity and less prone to toner layer peeling in the formed multicolor images, and an image forming method using the toner set.

[0018] Solution for solving the problem

[0019] To achieve the above objectives, the inventors conducted in-depth research and discovered that when a combination of styrene-acrylic resin and polyester resin is used as the binding resin in a positively charged toner, and a specific amount of nonionic surfactant is used as the dispersant for the ester wax, the toner exhibits an excellent balance between low-temperature fixing and heat-resistant preservation, is less prone to producing haze, and can form an image with excellent gloss uniformity, thus completing the present invention.

[0020] That is, the positively charged toner for electrostatic image development of the present invention is a positively charged toner for electrostatic image development containing coloring resin particles. The coloring resin particles include a binder resin, a colorant, a release agent, a release agent dispersant, and a charge control agent. The binder resin contains styrene-acrylic resin and polyester resin, the release agent contains ester wax, and the release agent dispersant contains a nonionic surfactant. The mass of the nonionic surfactant present on the surface of the toner particles is 0.1 to 500 ppm relative to the mass of the toner particles.

[0021] In one embodiment of the present invention, a charge control resin is included as the charge control agent.

[0022] In one embodiment of the present invention, the mass ratio of the styrene-acrylic resin to the polyester resin (styrene-acrylic resin: polyester resin) is 96:4 to 70:30.

[0023] In one embodiment of the present invention, the above-mentioned colored resin particles further contain a styrene-based thermoplastic elastomer.

[0024] In one aspect of the invention, the average roundness of the toner particles is 0.96 or higher, and the ratio of the volume average particle size (Dv) to the number average particle size (Dp) of the toner particles, i.e., the particle size distribution (Dv / Dp), is less than 1.3.

[0025] In one embodiment of the present invention, a polyfunctional ester compound containing a fatty acid having 10 to 22 carbon atoms and a polyol is used as the aforementioned ester wax.

[0026] Furthermore, the inventors have discovered that a toner group composed of the toners of the present invention described above can form a multicolor image with excellent gloss uniformity, and the toner layer is not easily peeled off in the formed multicolor image.

[0027] That is, the toner group of the present invention is a color toner group containing positively charged toners for electrostatic image development of multiple colors, including at least yellow toner, magenta toner and cyan toner as positively charged toners for electrostatic image development of the above-mentioned multiple colors, and all of the positively charged toners for electrostatic image development of the above-mentioned multiple colors are positively charged toners for electrostatic image development of the present invention.

[0028] The image forming method of the present invention is characterized in that an image is formed using the toner group of the present invention described above.

[0029] Invention Effects

[0030] According to the present invention, a toner with excellent low-temperature fixing and heat preservation properties, low tendency to produce haze, and ability to form images with excellent gloss uniformity can be provided.

[0031] Furthermore, according to the present invention, a toner set can be provided that can form a multicolor image with excellent gloss uniformity, and in the formed multicolor image, the toner layer is not easily peeled off. Furthermore, according to the present invention, an image forming method using the toner set is provided. Attached Figure Description

[0032] Figure 1 This is a schematic diagram illustrating an example of an image forming apparatus that can be used in image forming using the toner set of the present invention. Detailed Implementation

[0033] The positively charged toner for electrostatic image development of the present invention contains coloring resin particles, wherein the coloring resin particles comprise a binder resin, a colorant, a release agent, a release agent dispersant, and a charge control agent, wherein the binder resin comprises a styrene-acrylic resin and a polyester resin, the release agent comprises an ester wax, and the release agent dispersant comprises a nonionic surfactant, wherein the mass of the nonionic surfactant present on the surface of the toner particles is 0.1 to 500 ppm relative to the mass of the toner particles.

[0034] In the following text, the positively charged toner for electrostatic image development of the present invention will sometimes be referred to simply as "the toner of the present invention".

[0035] The toner of the present invention combines styrene-acrylic resin and polyester resin as binder resin, which can balance fixing performance and electrical stability under environmental changes. Therefore, it has excellent low-temperature fixing performance and is not prone to producing fog.

[0036] Furthermore, the toner of the present invention uses ester wax as a release agent and a specific amount of nonionic surfactant as a release agent dispersant, thereby improving the dispersibility of ester wax in the coloring resin particles. As a result, the decrease in heat resistance is suppressed, and low-temperature fixing performance is further improved. In addition, the toner of the present invention uses ester wax as a release agent, so that after the toner is fixed, the crystallization rate of the release agent upon rapid cooling is slow, thus reducing the likelihood of uneven gloss and enabling the formation of images with excellent gloss uniformity.

[0037] Furthermore, in the toner of the present invention, by keeping the amount of nonionic surfactant used within a specific range, the dispersibility of ester waxes can be improved, and the amount of surfactant remaining on the surface of the toner particles can be sufficiently reduced. When a large amount of surfactant is present on the surface of the toner particles, the surface of the toner particles absorbs moisture, thereby deteriorating the charge and easily causing problems such as haze or adhesion. In high temperature and high humidity environments, the surface of the toner particles becomes more prone to moisture absorption, making such problems even more likely to occur. In contrast, the toner of the present invention contains a sufficiently small amount of nonionic surfactant on the surface of the toner particles, thus exhibiting excellent charge stability, being less prone to haze, and also being less prone to adhesion, resulting in excellent heat resistance and storage properties.

[0038] As described above, the toner of the present invention uses specific binding resins, release agents, and release agent dispersants, and adjusts the amount of nonionic surfactant used as a release agent dispersant so that the amount of nonionic surfactant present on the surface of the toner particles as a release agent dispersant is within a specific range, thereby becoming a toner with excellent balance between low-temperature fixing and heat-resistant preservation, and less prone to haze. In addition, by using the toner of the present invention, images with excellent gloss uniformity can be formed.

[0039] In addition, in this invention, the heat resistance of the toner is sometimes simply referred to as "preservation".

[0040] Hereinafter, the manufacturing method of the coloring resin particles used in the toner of the present invention, the coloring resin particles, the external additives used in the toner of the present invention, and the toner particles constituting the toner of the present invention will be described in sequence.

[0041] Furthermore, in this invention, the "~" in the numerical range refers to the values ​​recorded before and after it as the lower limit and upper limit.

[0042] 1. Method for manufacturing colored resin particles

[0043] Generally, the manufacturing methods for coloring resin particles are broadly classified into dry methods such as pulverization and wet methods such as emulsion polymerization, suspension polymerization, and dissolution suspension polymerization. From the viewpoint of easily obtaining toners with excellent printing properties such as image reproducibility, wet methods are preferred. Among wet methods, from the viewpoint of easily obtaining toners with a small particle size distribution at the micrometer level, polymerization methods such as emulsion polymerization and suspension polymerization are preferred, and among polymerization methods, suspension polymerization is more preferred.

[0044] The emulsion polymerization coagulation method described above polymerizes emulsified polymerizable monomers to obtain resin microparticle emulsions, and then coagulates colorant dispersions to manufacture colored resin particles. Furthermore, the dissolution-suspension method described above dissolves or disperses binder resins, colorants, and other toning agents in an organic solvent, forms droplets in an aqueous medium, and removes the organic solvent to manufacture colored resin particles; both methods can utilize known techniques.

[0045] The colored resin particles used in this invention can be manufactured by a wet or dry process, but a wet process is preferred, and a suspension polymerization process is particularly preferred in the wet process, which can be manufactured by the following process.

[0046] (A) Suspension polymerization method

[0047] (A-1) Preparation process of polymeric monomer composition

[0048] First, a polymerizable monomer composition is prepared by mixing polymerizable monomers, polyester resins, colorants, release agents, release agent dispersants and charge control agents, as well as other additives such as acrylic resins containing acidic groups, styrene thermoplastic elastomers and molecular weight regulators as needed.

[0049] In the mixing process for preparing polymerizable monomer compositions, dispersers such as inline emulsifying dispersers or media-type emulsifying dispersers can be used. The preparation of the polymerizable monomer composition is preferably carried out by, for example, the following method: after mixing the polymerizable monomer, polyester resin, colorant, and molecular weight regulator using a media-type disperser and wet-milling, a charge control agent, release agent, and release agent dispersant are added, followed by further mixing. This method readily yields toners with excellent low-temperature fixing and heat-resistant storage properties.

[0050] (polymerizable monomers)

[0051] In this invention, polymerizable monomers refer to monomers and macromonomers having polymerizable functional groups. The polymerizable monomers contained in the polymerizable monomer composition are polymerized to become a styrene-acrylic resin as a binding resin. Furthermore, in this invention, styrene-acrylic resin refers to a copolymer of aromatic vinyl monomers and (meth)acrylic monomers. Without prejudice to the purpose of this invention, other monomers different from aromatic vinyl monomers and (meth)acrylic monomers may be further copolymerized. Here, (meth)acrylic monomers are monomers containing at least one selected from acryloyl and methacryloyl groups.

[0052] The aromatic vinyl monomers, (meth)acrylic monomers, and other monomers used in the synthesis of styrene-acrylic resins can be monovinyl monomers, crosslinking polymeric monomers, or macromolecular monomers, preferably containing monovinyl monomers as the main component. Specifically, relative to the total amount of polymeric monomers (100 parts by mass), the content of monovinyl monomers is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, further preferably 90 parts by mass or more, even more preferably 95 parts by mass or more, and particularly preferably 98 parts by mass or more.

[0053] Examples of the aforementioned monovinyl monomers include: aromatic vinyl monomers such as styrene, and styrene derivatives such as vinyltoluene and α-methylstyrene; acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and dimethylaminoethyl acrylate; methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and dimethylaminoethyl methacrylate; (meth)acrylic monomers such as acrylamide and methacrylamide, acrylic acid and methacrylic acid; nitrile compounds such as acrylonitrile and methacrylonitrile; and olefins such as ethylene, propylene and butene. These monovinyl monomers can be used alone or in combination of two or more.

[0054] In order to improve the electrical stability when the environment changes and thereby suppress the generation of fog, the aforementioned monovinyl monomer preferably contains an aromatic vinyl monomer and at least one selected from acrylates and methacrylates, and more preferably contains styrene and at least one selected from acrylates and methacrylates.

[0055] Furthermore, as an acrylate, it is particularly preferred to be selected from at least one of n-butyl acrylate, propyl acrylate, and 2-ethylhexyl acrylate. As a methacrylate, it is particularly preferred to be selected from at least one of n-butyl methacrylate, propyl methacrylate, and 2-ethylhexyl methacrylate.

[0056] In a total of 100 parts by mass of the monovinyl monomer, the total content of aromatic vinyl monomer, acrylate and methacrylate is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, further preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, and particularly preferably more than 99.95 parts by mass.

[0057] Furthermore, from the perspective of achieving a good balance between the low-temperature fixing properties and heat-resistant preservation of the toner, as well as suppressing the generation of fog, it is preferable that the above-mentioned monovinyl monomer contains styrene and at least one selected from acrylates and methacrylates, and the total mass ratio of styrene to acrylates and methacrylates (styrene:(meth)acrylate) is in the range of 50:50 to 90:10, more preferably in the range of 60:40 to 80:20.

[0058] Furthermore, the structure and proportion of each monomer unit constituting the resin can be determined based on the composition of the polymerizable monomers used in the resin synthesis. Additionally, it can also be determined based on... 1 The integral value from the H-NMR measurement is calculated.

[0059] The aforementioned polymerizable monomers may contain both monovinyl monomers and macromonomers. By including macromonomers in the aforementioned polymerizable monomers, the balance between the toner's shelf life and its low-temperature fixing properties can be improved.

[0060] Examples of macromonomers include reactive oligomers and polymers having polymerizable carbon-carbon unsaturated double bonds at the ends of their molecular chains and typically having a number-average molecular weight of 1000 or more and 30000 or less. Examples of such macromonomers include styrene macromonomers, styrene-acrylonitrile macromonomers, polyacrylate macromonomers, and polymethacrylate macromonomers. From the perspective of easily controlling the glass transition temperature (Tg) of the toner, at least one selected from polyacrylate macromonomers and polymethacrylate macromonomers is preferred. Examples of acrylates used as polyacrylate macromonomers include, for example, acrylates that are the same as those used as the aforementioned monovinyl monomers; examples of methacrylates used as polymethacrylate macromonomers include, for example, methacrylates that are the same as those used as the aforementioned monovinyl monomers. As the aforementioned macromonomer, from the perspective of easily bringing the glass transition temperature (Tg) of the toner into the aforementioned preferred range, it is preferable to appropriately select a macromonomer that, by containing the macromonomer in the aforementioned polymerizable monomer, results in a higher glass transition temperature (Tg) of the adhesive resin compared to the case where it is not contained.

[0061] Commercially available products can be used as the aforementioned macromonomers. Examples of commercially available macromonomers include the AA-6, AS-6, AN-6S, AB-6, and AW-6S series manufactured by Toa Synthetic Co., Ltd.

[0062] The aforementioned macromonomers can be used alone, or in combination of two or more.

[0063] When the polymerizable monomer contains the macromonomer, the content of the macromonomer is not particularly limited, but is preferably 0.03 parts by mass or more and 5 parts by mass or less, more preferably 0.05 parts by mass or more and 1 part by mass or less, relative to 100 parts by mass of the monovinyl monomer.

[0064] The aforementioned polymerizable monomers may contain crosslinking polymerizable monomers in addition to the aforementioned monovinyl monomers. The inclusion of crosslinking polymerizable monomers in the aforementioned polymerizable monomers facilitates improved shelf life and heat-induced displacement resistance of the toner, and is therefore preferred.

[0065] Here, cross-linking polymerizable monomers refer to monomers having two or more polymerizable functional groups.

[0066] Examples of crosslinking polymerizable monomers include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and their derivatives; ester compounds in which alcohols having two or more hydroxyl groups are bonded to two or more carboxylic acids, such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; other divinyl compounds such as N,N-divinylaniline and divinyl ether; and compounds having three or more vinyl groups, with aromatic divinyl compounds being particularly preferred.

[0067] The aforementioned cross-linking polymeric monomers can be used alone, or in combination of two or more.

[0068] When the above-mentioned polymerizable monomer contains the above-mentioned crosslinking polymerizable monomer, the content of the above-mentioned crosslinking polymerizable monomer is not particularly limited. It is preferably 0.05 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the above-mentioned monovinyl monomer, more preferably 0.06 parts by mass or more and 1.5 parts by mass or less, and even more preferably 0.08 parts by mass or more and 0.8 parts by mass or less.

[0069] The content of the aforementioned polymerizable monomers is not particularly limited. From the perspective of achieving a good balance between the low-temperature fixing and heat-resistant preservation properties of the toner and suppressing the generation of fog, the content is preferably 60 parts by mass or more and 90 parts by mass or less, more preferably 65 parts by mass or more and 85 parts by mass or less, and even more preferably 70 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the total solid content contained in the aforementioned polymerizable monomer composition.

[0070] Furthermore, in this invention, solid components refer to all components other than solvents, and solid components also include liquid monomers, etc.

[0071] Furthermore, the content of polymerizable monomers relative to 100 parts by weight of total solids in the polymerizable monomer composition is equivalent to the content of styrene-acrylic resin relative to 100 parts by weight of colored resin particles.

[0072] (Polyester-based resin)

[0073] As a polyester resin, any polyester resin that is commonly used as a binder resin as a colorant can be used, without particular limitation. However, it is preferable to use a polyester resin formed by polycondensation of a carboxylic acid component containing a polycarboxylic acid compound and an alcohol component containing a polyol.

[0074] In addition, carboxylic acid components refer to compounds containing carboxyl groups or carboxylic acid derivative groups, while polycarboxylic acid compounds refer to compounds having two or more carboxyl groups or carboxylic acid derivative groups in one molecule. Examples of carboxylic acid derivative groups include amide groups, ester groups, acid anhydride groups, and acid halides.

[0075] In the synthesis of polyester resins, carboxylic acid components and alcohol components can be used individually or in combination of two or more.

[0076] From the perspective of easily obtaining toners that have an excellent balance between low-temperature fixing and heat preservation, excellent environmental stability, and are not prone to fogging, the polycarboxylic acid compounds used in the synthesis of polyester resins preferably contain at least a cyclic dicarboxylic acid component (B).

[0077] Examples of cyclic dicarboxylic acid compounds (B) include aromatic dicarboxylic acid compounds, alicyclic dicarboxylic acid compounds, and their derivatives, with alicyclic dicarboxylic acid compounds and their derivatives being particularly preferred.

[0078] Examples of aromatic dicarboxylic acid compounds include 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenylcarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid and their alkyl-substituted derivatives, as well as their anhydrides, halides, esters, amides and other derivatives.

[0079] Alicyclic dicarboxylic acids are compounds that possess an alicyclic structure and two carboxyl groups in their molecular structure. Derivatives of alicyclic dicarboxylic acids are compounds in which at least one carboxyl group of the alicyclic dicarboxylic acid is replaced by a carboxylic acid derivative group.

[0080] Examples of alicyclic structures include monocyclic rings such as cyclopentane, cyclohexane, cycloheptane, and cyclohexene; and polycyclic alicyclic structures such as norbornene and norbornene.

[0081] Preferred alicyclic dicarboxylic acid compounds and their derivatives include, for example, alicyclic dicarboxylic acid compounds in which a carboxyl group or a carboxylic acid derivative group is bonded to two carbon atoms constituting the alicyclic ring. Particularly preferred are alicyclic dicarboxylic acids represented by the following general formula (1) or (2), and alicyclic dicarboxylic acid compounds and their derivatives in which an alkyl group is bonded to the alicyclic ring as a substituent. The alkyl group bonded to the alicyclic ring as a substituent is preferably an alkyl group having 1 to 8 carbon atoms, more preferably methyl, ethyl, propyl, or isopropyl.

[0082] [Chemical Formula 1]

[0083]

[0084] [Chemical Formula 2]

[0085]

[0086] In formulas (1) and (2) above, R is an alkyl group.

[0087] Alicyclic dicarboxylic acid compounds can be obtained by reacting diene compounds such as butadiene, isoprene, pentadiene, and cyclopentadiene with anhydrous maleic acid, and then hydrogenating them as needed.

[0088] Examples of alicyclic dicarboxylic acid compounds include: tetrahydroterephthalic acid, tetrahydroisophthalic acid, tetrahydrophthalic acid; hexahydroterephthalic acid, hexahydroisophthalic acid, hexahydrophthalic acid; 3-alkyltetrahydroterephthalic acid, 4-alkyltetrahydroterephthalic acid, 3-alkyltetrahydroisophthalic acid, 4-alkyltetrahydroisophthalic acid, 3-alkyltetrahydrophthalic acid, 4-alkyltetrahydrophthalic acid; 3-alkylhexahydroterephthalic acid. Formic acid, 4-alkylhexahydroterephthalic acid, 3-alkylhexahydroisophthalic acid, 4-alkylhexahydroisophthalic acid, 3-alkylhexahydrophthalic acid, 4-alkylhexahydrophthalic acid; bis(β-hydroxyethyl) hexahydroterephthalate; 3,6-methylene-tetrahydroterephthalic acid, 3,6-methylene-tetrahydroisophthalic acid, 3,6-methylene-tetrahydrophthalic acid; 3,6-methylene-hexahydroterephthalic acid, 3 3,6-Nylidene-hexahydrophthalic acid, 3,6-Nylidene-hexahydrophthalic acid; 2-alkyl-3,6-Nylidene-tetrahydrophthalic acid, 3-alkyl-3,6-Nylidene-tetrahydrophthalic acid, 2-alkyl-3,6-Nylidene-tetrahydrophthalic acid, 3-alkyl-3,6-Nylidene-tetrahydrophthalic acid, 2-alkyl-3,6-Nylidene-tetrahydrophthalic acid, 3-alkyl-3 6-Neptemethylene-tetrahydrophthalic acid; 2-alkyl-3,6-neptemethylene-hexahydrophthalic acid, 3-alkyl-3,6-neptemethylene-hexahydrophthalic acid; 2-alkyl-3,6-neptemethylene-hexahydroisophthalic acid, 3-alkyl-3,6-neptemethylene-hexahydroisophthalic acid, 2-alkyl-3,6-neptemethylene-hexahydrophthalic acid, 3-alkyl-3,6-neptemethylene-hexahydrophthalic acid, etc.

[0089] Examples of derivatives of alicyclic dicarboxylic acid compounds include tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3-alkyltetrahydrophthalic anhydride, 3-alkylhexahydrophthalic anhydride, 4-alkyltetrahydrophthalic anhydride, 4-alkylhexahydrophthalic anhydride, and other acid anhydrides, halides, esters, and amides.

[0090] As alicyclic dicarboxylic acid compounds and their derivatives, 3-alkyltetrahydrophthalic acid, 3-alkylhexahydrophthalic acid, 4-alkyltetrahydrophthalic acid, 4-alkylhexahydrophthalic acid and their anhydrides are particularly preferred from the perspective of improving the low-temperature fixing properties of toners and suppressing the generation of fog.

[0091] In addition, as a cyclic dicarboxylic acid compound (B), it may also include a polycarboxylic acid compound (A1) containing an amino group or its salt.

[0092] Examples of polycarboxylic acid compounds (A1) containing an amino group or its salt include, for example, aromatic polycarboxylic acids such as aminoterephthalic acid, 5-aminoisophthalic acid, methyl 5-aminoisophthalate, 4-aminophthalic acid, 4-aminophthalic anhydride, 4-aminonaphthyl-2,7-dicarboxylic acid, and 5-[4-aminophenoxy]isophthalic acid; and alicyclic polycarboxylic acids such as 5-aminohexahydroisophthalic acid, methyl 5-aminohexahydroisophthalate, dimethyl 5-aminohexahydroisophthalate, 4-aminohexahydrophthalic acid, 4-aminohexahydrophthalic anhydride, 5-aminotetrahydroisophthalic acid, methyl 5-aminotetrahydroisophthalate, 4-aminotetrahydrophthalic acid, and 4-aminotetrahydrophthalic anhydride.

[0093] The amount of cyclic dicarboxylic acid compound (B) relative to the total carboxylic acid components is preferably 70 to 100 mol%, more preferably 80 to 100 mol%. When the amount of cyclic dicarboxylic acid compound (B) is within the above range, it is easy to obtain a toner with an excellent balance between low-temperature fixing and heat preservation, excellent environmental stability, and low tendency to generate haze.

[0094] The carboxylic acid component used in the synthesis of polyester resins may, as needed, include at least one selected from chain dicarboxylic acid compounds (D) and tricarboxylic acid compounds (F).

[0095] Examples of chain dicarboxylic acid compounds (D) include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, etc.

[0096] Examples of carboxylic acid compounds (F) that are trivalent or higher include trimellitic acid, pyromellitic acid, and pyromellitic acid.

[0097] The proportion of the chain dicarboxylic acid compound (D) is preferably less than 30 mol% of the total carboxylic acid components. When this proportion increases, the glass transition temperature and melt viscosity decrease, the anti-blocking properties of the toner decrease, and thermal displacement occurs.

[0098] The proportion of ternary or higher carboxylic acid compounds (F) is preferably 5 mol% or less of the total carboxylic acid components. When this proportion increases, the melt viscosity of the toner increases due to the higher weight-average molecular weight of the polyester resin, resulting in poorer fixing properties of the toner.

[0099] From the perspective of easily obtaining toners that have an excellent balance between low-temperature fixing and heat preservation, excellent environmental stability, and are not prone to fogging, the polyols used in the synthesis of polyester resins preferably include at least cyclic diols (C).

[0100] Examples of cyclic diols (C) include aromatic diols and alicyclic diols, with alicyclic diols being particularly preferred.

[0101] Examples of aromatic diols include, for example, ethylene oxide adducts of terephthalic acid, isophthalic acid, o-phthalic acid, 1,4-benzenediol, ethylene oxide adducts of bisphenol A, and propylene oxide adducts.

[0102] Examples of alicyclic diols include: 2,2-bis(4-hydroxycyclohexyl)-propane (i.e., hydrogenated bisphenol A), 1,4-bis(hydroxymethyl)cyclohexane, 1,3-bis(hydroxymethyl)cyclohexane, 1,2-bis(hydroxymethyl)cyclohexane, 2,2,4,4-tetramethyl-1,3-cyclohexanediol, 1,4-cyclohexanediol, ethylene oxide adducts and propylene oxide adducts of hydrogenated bisphenol A, tricyclodecanediol, tricyclodecanediethanol, dicyclohexyl-4,4'-diol, etc. Among these, bis(hydroxycyclohexyl)-alkanes such as hydrogenated bisphenol A are preferred.

[0103] The amount of cyclic diol (C) is preferably 2 to 100 mol% of the total alcohol content, more preferably 10 to 60 mol%, and even more preferably 20 to 50 mol%. When the amount of cyclic diol (C) is too small, the glass transition temperature, melt viscosity, and resistance to sticking decrease, and thermal drift occurs. By reducing the amount of alicyclic diol, the fixing properties of the toner can be improved.

[0104] The alcohol component used in the synthesis of polyester resins preferably also includes chain diols (E). Furthermore, it may also include triols or more (G).

[0105] Examples of chain diols (E) include linear aliphatic diols such as ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, and polytetramethylene glycol; and branched aliphatic diols such as propylene glycol, dipropylene glycol, polypropylene glycol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, and 2-ethyl-2-butyl-1,3-propanediol. Linear aliphatic diols are preferred among these, with ethylene glycol being particularly preferred.

[0106] The amount of chain diol (E) is preferably 40-98 mol% of the total polyol components constituting the polyester resin, more preferably 50-97 mol%. When the amount of chain diol (E) is too small, the melt viscosity increases and the fixing property decreases. Conversely, when the amount of chain diol is too large, the glass transition temperature decreases, the melt viscosity decreases, the anti-blocking property decreases, and thermal drift occurs.

[0107] Examples of alcohols (G) that are three or more groups include trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, trimethylolethane, cyclohexanetriol, tri(hydroxymethyl)cyclohexane, and 2,4-bis(hydroxyethyl)-1-aminocyclohexane.

[0108] The proportion of ternary or higher alcohols (G) is preferably 5 mol% or less of the total alcohol content. When this proportion increases, the melt viscosity of the toner increases due to the higher weight-average molecular weight of the polyester resin, resulting in poorer fixing properties of the toner.

[0109] In addition, as a cyclic diol (C) or a chain diol (E), it may also contain a polyol (A2) containing an amino group or its salt.

[0110] Examples of polyols (A2) containing an amino group or its salt include, for example, chain aliphatic polyols such as 2-amino-2-methyl-1,3-propanediol and diethanolamine; aromatic polyols such as 2-amino-4-hydroxymethylbenzyl alcohol, 2-amino-3-hydroxymethylbenzyl alcohol, 4-amino-2-hydroxymethylbenzyl alcohol, and 5-amino-3-hydroxymethylbenzyl alcohol; and their ammonium salts.

[0111] When the polyester resin contained in the toner of the present invention is a polyester resin formed by condensation polymerization of at least one selected from a polycarboxylic acid compound (A1) containing an amino group or its salt and a polyol (A2) containing an amino group or its salt, it is preferred from the viewpoint of easily improving the low-temperature fixing properties of the toner and being less prone to haze. This polyester resin is preferably a polyester resin having an amino group or an ammonium salt. The polyester resin having an ammonium salt can be formed by cocondensation polymerization of one or more selected from a polycarboxylic acid compound (A1) having an ammonium salt and a polyol (A2) having an ammonium salt, or it can be formed by cocondensation polymerization of one or more selected from a polycarboxylic acid compound (A1) having an amino group and a polyol (A2) having an amino group followed by ammonium salting.

[0112] In the polyester resin contained in the toner of the present invention, the total amount of a polycarboxylic acid compound (A1) containing an amino group or its salt and a polyol (A2) containing an amino group or its salt is typically 0.2 to 30 mol%, preferably 0.5 to 10 mol%, and more preferably 1.0 to 5 mol%, relative to 100 mol% of all monomers constituting the polyester resin (total of all carboxylic acid components and all alcohol components). By containing at least one selected from a polycarboxylic acid compound (A1) containing an amino group or its salt and a polyol (A2) containing an amino group or its salt as a polycondensation component, the dispersibility of the pigment in the toner can be improved and the charge of the toner can be controlled.

[0113] The number-average molecular weight (Mn) of the polyester resin contained in the toner of the present invention is preferably 1,500 to 20,000, more preferably 2,000 to 10,000, and even more preferably 2,500 to 8,000; the weight-average molecular weight (Mw) is preferably 5,000 to 300,000, more preferably 7,000 to 100,000, and even more preferably 8,000 to 20,000. By having the molecular weight within this range, a toner with excellent low-temperature fixing properties and heat-shift resistance can be obtained. When the number-average molecular weight (Mn) and weight-average molecular weight (Mw) are less than the above ranges, the cohesiveness of the polyester resin decreases and its shelf life deteriorates; conversely, when the weight-average molecular weight (Mw) is greater than the above ranges, productivity decreases and the fixing properties of the toner deteriorate.

[0114] Furthermore, in this invention, the weight-average molecular weight Mw and number-average molecular weight Mn of the resin can be calculated from polystyrene by gel permeation chromatography (GPC) of tetrahydrofuran (THF).

[0115] The glass transition temperature of the polyester resin is preferably 40–90°C, and particularly preferably 50–80°C. If the glass transition temperature is within the above range, the shelf life of the toner is improved.

[0116] Furthermore, in this invention, the glass transition temperature (Tg) of the resin can be determined, for example, according to ASTM D3418-82. Specifically, the sample can be heated at a rate of 10°C / min using a differential scanning calorimeter (manufactured by Seiko Electric Industries, Ltd.: SSC5200), and the temperature at which the maximum endothermic peak is observed in the DSC curve obtained during this process can be taken as the glass transition temperature.

[0117] The hydroxyl value of polyester resins is typically 1–100 mg KOH / g, preferably 5–80 mg KOH / g. When the hydroxyl value is low, fixing performance deteriorates, resulting in greater unevenness and reduced smoothness of the image surface. When the hydroxyl value is high, thermal offset leads to a decrease in temperature, which in turn increases hydrophilicity, makes the charge more susceptible to changes in the environment, and increases the likelihood of fogging.

[0118] In addition, to reduce the impact of moisture in high temperature and high humidity environments, it is preferable to further reduce the amount of aromatic rings contained in the polyester resin.

[0119] The polyester resin contained in the colorant of the present invention can be manufactured by a known method, namely polycondensation. From the viewpoint of easily adjusting the molecular weight and hydroxyl value of the polyester within a preferred range, it is preferable that, during the polycondensation of the carboxylic acid component and the alcohol component, the total number of hydroxyl values ​​[X] of the alcoholic reactive groups in all monomers of the total carboxylic acid component and the alcohol component is not less than the total number of acid values ​​[Y] of the carboxylic acid reactive groups.

[0120] The ratio (equivalent ratio) of the total number of hydroxyl values ​​[X] of alcoholic reactive groups to the total number of acid values ​​[Y] of carboxylic acid reactive groups, i.e., [X] / [Y], is preferably 1.00 or more, more preferably 1.01 to 1.5, and particularly preferably in the range of 1.03 to 1.3. Here, alcoholic reactive groups refer to alcoholic functional groups that form ester bonds, and examples typically include hydroxyl groups. Carboxylic acid reactive groups refer to carboxylic acid functional groups that form ester bonds, and examples typically include carboxyl groups or carboxylic acid derivative groups.

[0121] The polycondensation reaction is carried out, for example, at a reaction temperature of 100–300°C, preferably 150–280°C, and particularly preferably in the presence of an inactive gas. Toluene, xylene, or other water-acid-soluble organic solvents can also be used as needed. Furthermore, the polycondensation reaction can be carried out under reduced pressure (typically 0.1–500 mmHg, preferably 0.5–200 mmHg, more preferably 1–50 mmHg). In addition, an esterification catalyst is typically used in this polycondensation reaction. Examples of esterification catalysts include Brønsted acids such as p-toluenesulfonic acid, sulfuric acid, and phosphoric acid; calcium acetate, zinc acetate, manganese acetate, and zinc stearate; acetylacetonates of iron and zinc; metal alkoxides; organometallic compounds such as alkyltin oxide, dialkyltin oxide, and organotitanium compounds; metal oxides such as tin oxide, antimony oxide, titanium oxide, and vanadium oxide; and heteropoly acids. From the perspective of increasing the molecular weight of the obtained polyester resin, titanium alkoxides such as tetrabutoxytitanium, heteropoly acids, or acetylacetonate iron are preferred.

[0122] To obtain a polyester resin, the aforementioned carboxylic acid component and alcohol component can be fed in a desired composition ratio and reacted in one step, or the reaction can be carried out in stages to adjust the molecular weight. When using at least one of a polycarboxylic acid compound (A1) containing an amino group or its salt and a polyol (A2) containing an amino group or its salt, the reaction can be carried out in stages by the following method.

[0123] That is, a carboxylic acid component containing a cyclic dicarboxylic acid compound (B) is polycondensed with an alcohol component containing a cyclic diol (C) to obtain a precursor. Here, the carboxylic acid component and alcohol component used for the precursor preferably do not contain a polycarboxylic acid compound (A1) containing an amino group or its salt, or a polyol (A2) containing an amino group or its salt. Furthermore, the carboxylic acid component and alcohol component used for the precursor preferably also contain at least one selected from a chain dicarboxylic acid compound (D) and a chain diol (E).

[0124] Next, the obtained precursor is subjected to polycondensation with at least one selected from a polycarboxylic acid compound (A1) containing an amino group or its salt, a polyol (A2) containing an amino group or its salt, and at least one selected from a polycarboxylic acid compound (H) and a polyol (I).

[0125] When determining the precursor by gel permeation chromatography (GPC), its number-average molecular weight, converted to polystyrene, is 1500–5000, preferably 2000–4000. Within this molecular weight range, the dispersibility of the polyester resin increases. The glass transition temperature of the precursor is preferably 40°C or higher, particularly preferably 50–80°C. If the glass transition temperature is above 40°C, the toner's retention is improved.

[0126] The aforementioned polycarboxylic acid compound (H) is not particularly limited, and examples include cyclic dicarboxylic acid compounds (B) such as aromatic dicarboxylic acid compounds and alicyclic dicarboxylic acid compounds as described above, chain dicarboxylic acid compounds (D), and trivalent or higher carboxylic acid compounds (F). Among these, cyclic dicarboxylic acid compounds such as terephthalic acid, tetrahydroterephthalic acid, and hexahydroterephthalic acid, in which two non-adjacent carbon atoms constituting the ring are respectively bonded to a carboxyl group or a carboxylic acid derivative group, are preferred.

[0127] The polyols (I) mentioned above are not particularly limited, and examples include aromatic diols, alicyclic diols such as those mentioned above, cyclic diols (C), chain diols (E), and alcohols with three or more groups (G).

[0128] The total amount of the polycarboxylic acid compound (H) or polyol (I) used in the cocondensation with the precursor is preferably 10 to 50 parts by mass, and particularly preferably 20 to 40 parts by mass, relative to 100 parts by mass of the precursor. Since the amount of this polycarboxylic acid compound or polyol is within the above range, it is possible to increase the molecular weight without impairing the melt properties, and therefore is preferred.

[0129] Preferably, the content of polyester resin is adjusted such that the mass ratio of styrene-acrylic resin to polyester resin (styrene-acrylic resin: polyester resin) is in the range of 96:4 to 70:30. More preferably, the mass ratio is 96:4 to 80:20, and even more preferably, 96:4 to 90:10. Here, the mass of the styrene-acrylic resin is equivalent to the mass of the polymerizable monomers described above.

[0130] When the content of polyester resin is above the lower limit mentioned above, the melt viscosity of the toner is sufficiently reduced, thus improving the toner's fixing properties. When the content of polyester resin is below the upper limit mentioned above, the toner's charge stability remains good even in high-temperature and high-humidity environments, thus suppressing the formation of fog and reducing image quality. By keeping the polyester resin content within the above range, both the toner's fixing properties and its charge stability under environmental changes are achieved.

[0131] (Coloring agent)

[0132] The colorant contained in the above polymeric monomer composition can be appropriately selected from colorants that have been used in toners in the past, without particular limitation, and black, cyan, yellow or magenta colorants can be used.

[0133] As a black colorant, materials such as carbon black, titanium black, and magnetic powders such as zinc oxide and nickel oxide can be used.

[0134] As cyan colorants, cyan pigments such as copper phthalocyanine pigments and their derivatives, anthraquinone pigments, and cyan dyes can be used. Specifically, examples include CI Pigment Blue 2, 3, 6, 15, 15:1, 15:2, 15:3, 15:4, 16, 17:1, 60; and CI Solvent Blue 70.

[0135] As a yellow colorant, various yellow pigments can be used, such as monoazo pigments and diazo pigments, fused polycyclic pigments, and yellow dyes. Specifically, examples include CI Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 74, 83, 93, 97, 120, 138, 155, 180, 181, 185, 186, 213, and 214; and CI Solvent Yellow 98 and 162.

[0136] As a magenta colorant, various azo pigments such as monoazo and diazo pigments, fused polycyclic pigments, and magenta dyes can be used. Specifically, examples include CI Pigment Red 31, 48, 57, 1, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 149, 150, 163, 170, 184, 185, 187, 202, 206, 207, 209, 237, 238, 251, 254, 255, 269; CI Pigment Violet 19; and CI Solvent Red 1, 3, 8, 23, 2... 4, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121; CI Disperse Red 9; CI Solvent Violet 8, 13, 14, 21, 27; CI Disperse Violet 1; CI Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; CI Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28, etc.

[0137] The aforementioned colorants can be used alone or in combination of two or more. To improve image quality, pigments and dyes can also be used together as the aforementioned colorants.

[0138] When using two or more pigments in combination, it is preferable that the two or more pigments be mixed crystal pigments from the perspective of forming high-quality images. Specifically, examples of mixed crystal pigments include a mixture of CI pigment Violet 19 and CI pigment Red 122, which will be described later.

[0139] In black toners, carbon black is preferred as a colorant, from the perspective of being able to form high-quality images.

[0140] In cyan colorants, copper phthalocyanine pigments and their derivatives are preferred as colorants, from the perspective of being able to form high-quality images.

[0141] In yellow toners, as colorants, from the perspective of improving preservation and enabling the formation of high-quality images, it is preferable to contain at least one selected from diazo pigments such as CI Pigment Yellow 93, 155, 180, 214, and 219, and yellow dyes such as CI Solvent Yellow 98 and 162; more preferably, it contains at least one selected from CI Pigment Yellow 155, 214, and CI Solvent Yellow 98; and even more preferably, it contains at least one selected from CI Pigment Yellow 214 and CI Solvent Yellow 98. Furthermore, in yellow toners, as colorants, from the perspective of improving preservation and enabling the formation of high-quality images, it is preferable to combine diazo pigments and yellow dyes; more preferably, it contains at least one selected from CI Pigment Yellow 155 and CI Pigment Yellow 214, and CI Solvent Yellow 98; and even more preferably, it contains a combination of CI Pigment Yellow 214 and CI Solvent Yellow 98.

[0142] Furthermore, in the yellow colorant, the mass ratio of yellow pigment to yellow dye (yellow pigment: yellow dye) is preferably in the range of 50:50 to 95:5, more preferably in the range of 60:40 to 90:10. Here, the yellow pigment in the yellow colorant is preferably a diazo pigment, more preferably at least one of CI Pigment Yellow 155 and CI Pigment Yellow 214, and even more preferably CI Pigment Yellow 214. The yellow dye in the yellow colorant is preferably CI Solvent Yellow 98.

[0143] In magenta toners, CI Pigment Red 122 is preferred as a colorant, from the perspective of forming high-quality images. Furthermore, it is more preferable to use CI Pigment Red 122 and CI Pigment Violet 19 together, and a mixture of CI Pigment Violet 19 and CI Pigment Red 122 is particularly preferred.

[0144] The mixed crystals of CI pigment violet 19 and CI pigment red 122 can be produced by, for example, the method described in U.S. Patent No. 3,160,510, which involves simultaneously recrystallizing the mixed crystal components from sulfuric acid or other suitable solvents, followed by solvent treatment after salt milling as needed; or the method described in German Patent Application Publication No. 1217,333, which involves solvent treatment after cyclization of the substituted diaminoterephthalic acid mixture.

[0145] When the magenta tint contains CI Pigment Violet 19 and CI Pigment Red 122 as colorants, the mass ratio of CI Pigment Violet 19 to CI Pigment Red 122 is preferably 80:20 to 20:80, more preferably 70:30 to 30:70, and even more preferably 60:40 to 40:60.

[0146] The content of the aforementioned colorant is appropriately adjusted according to the type of colorant in a way that the desired color can be obtained, without particular limitation. It is preferably 1 part or more and 20 parts or less of styrene-acrylic resin included as a binding resin relative to 100 parts by weight, more preferably 5 parts or more and 15 parts or less of styrene-acrylic resin.

[0147] (Release agent)

[0148] Ester waxes are used as release agents. As ester waxes, synthetic ester waxes obtained by esterification of alcohols and carboxylic acids are preferred; polyfunctional or monoester waxes are more preferably used. Furthermore, the alcohol and carboxylic acid used in the synthesis of the ester wax can be used individually or in combination of two or more.

[0149] Furthermore, as the ester wax, long-chain fatty acid ester waxes made from long-chain fatty acids with 10 or more carbon atoms are preferred. Since the long-chain fatty acid ester wax has a strong effect on improving dispersibility from styrene-based thermoplastic elastomers, its low-temperature fixing properties can be particularly improved by using it in combination with styrene-based thermoplastic elastomers.

[0150] As a polyfunctional ester wax, a polyfunctional ester compound of fatty acid and polyol with 10 to 22 carbon atoms is particularly preferred. The fatty acid used in the polyfunctional ester compound is more preferably 14 to 22 carbon atoms, and even more preferably 16 to 22 carbon atoms.

[0151] The aforementioned fatty acids can be saturated or unsaturated fatty acids, with highly stable saturated fatty acids being preferred. Furthermore, the aforementioned fatty acids can be monocarboxylic acids or polycarboxylic acids, with monocarboxylic acids being preferred. Examples of preferred monocarboxylic acids include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and oleic acid, with stearic acid, arachidic acid, and behenic acid being particularly preferred.

[0152] Examples of polyols used in multifunctional ester waxes include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, and 1... Diols such as 3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol; triols such as glycerol, trimethylolethane, and trimethylolpropane; tetraols such as pentaerythritol, erythritol, and diglycerol; pentaols such as xylitol and triglycerides; and hexaols such as sorbitol and dipentaerythritol, and octaols such as hexaglycerides. Polyols with four to eight members are particularly preferred.

[0153] Furthermore, as the aforementioned polyfunctional ester wax, at least one selected from pentaerythritol ester compounds, glycerol ester compounds, and dipentaerythritol ester compounds is preferred. Examples of such preferred polyfunctional ester waxes include pentaerythritol tetrapalmitate, pentaerythritol tetrabenzyl ester, pentaerythritol tetrastearate, etc.; glycerol ester compounds such as hexaglycerol tetrabenzyl palmitate, hexaglycerol octabenzyl ester, hexaglycerol pentabenzyl ester, hexaglycerol tetrabenzyl ester, triglycerol pentabenzyl ester, diglycerol tetrabenzyl ester, triglycerol tribenzyl ester; and dipentaerythritol hexamyristate, dipentaerythritol hexapalmitate, etc. Glycerol ester compounds are particularly preferred. Since styrene-based thermoplastic elastomers have a strong effect on improving dispersibility, and therefore, the low-temperature fixing properties of the toner can be particularly improved by using them in combination with styrene-based thermoplastic elastomers, glycerol ester compounds are preferred.

[0154] As monoester waxes, monoester compounds of monocarboxylic acids having 10 to 22 carbon atoms and monohydric alcohols having 10 to 22 carbon atoms are particularly preferred. The monocarboxylic acids are more preferably 14 to 22 carbon atoms, and even more preferably 16 to 22 carbon atoms. The monohydric alcohols are more preferably 14 to 22 carbon atoms, and even more preferably 16 to 22 carbon atoms.

[0155] Examples of preferred monocarboxylic acids include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid (eicosanoic acid), behenic acid, and oleic acid, with palmitic acid, stearic acid, arachidic acid, and behenic acid being particularly preferred.

[0156] Examples of preferred monohydric alcohols include lauryl alcohol, myristyl alcohol, palmitol (1-hexadecyl alcohol), stearyl alcohol, arachidyl alcohol (eicosyl alcohol), behenyl alcohol, and oleyl alcohol, with palmitol, stearyl alcohol, arachidyl alcohol, and behenyl alcohol being particularly preferred.

[0157] As a monoester wax, there are no particular limitations, but from the perspective of improving the balance between toner preservation and low-temperature fixing properties, behenyl palmitate, behenyl stearate, behenyl eicosanoate, behenyl behenate, eicosanoate palmitate, eicosanoate stearate, eicosanoate eicosanoate, eicosanoate behenate, stearyl stearate, eicosanoate stearate, stearyl behenate, hexadecyl eicosanoate, and hexadecyl behenate are preferred. Behenyl stearate, behenyl palmitate, and stearyl behenate are particularly preferred.

[0158] The molecular weight of the ester wax is preferably in the range of 400 or more and 3500 or less, more preferably in the range of 500 or more and 3000 or less. When the molecular weight of the ester wax is above the lower limit mentioned above, the exudation of the ester wax can be suppressed, and the generation of UFP from the ester wax can be suppressed. When the molecular weight of the ester wax is below the upper limit mentioned above, the low-temperature fixing properties of the toner can be improved.

[0159] Furthermore, from the perspective of improving the balance between the toner's preservation and low-temperature fixing properties, the melting point of the release agent is preferably in the range of 50°C or higher and 90°C or lower, more preferably in the range of 60°C or higher and 85°C or lower, and even more preferably in the range of 65°C or higher and 80°C or lower.

[0160] Without prejudice to the purpose of the present invention, the toner of the present invention may also contain release agents other than ester waxes. As release agents other than ester waxes, examples include release agents commonly used as release agents in toners, without particular limitation, such as polyolefin waxes like polyethylene wax and polypropylene wax, synthetic waxes like Fischer-Tropsch wax, petroleum-based waxes like paraffin wax, microcrystalline wax, and petroleum-based waxes like petrolatum wax; natural waxes like candelilla wax, carnauba wax, rice bran wax, Japanese wax, and jojoba wax; and mineral waxes like lignite wax, pure terrestrial wax, and terrestrial wax.

[0161] When a release agent other than ester wax is included, the content of ester wax is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and even more preferably 99% by mass or more, relative to the total amount of 100% by mass of the release agent. When the content of ester wax is at or above the above-mentioned lower limit, the reduction in the performance of the toner can be sufficiently suppressed. Specifically, the deterioration of the balance between the toner's shelf life and low-temperature fixing properties, the generation of haze, the occurrence of uneven gloss, and the exudation of the release agent can be sufficiently suppressed.

[0162] Furthermore, from the perspective of improving the balance between the toner's preservation and low-temperature fixing properties, the content of glyceryl ester compound in 100% by mass release agent is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0163] Furthermore, from the perspective of improving the balance between the toner's shelf life and low-temperature fixing properties, polyglycerol ester compounds such as hexaglycerol tetrabenzyl palmitate, hexaglycerol octabenzyl, pentaglycerol heptabenzyl, tetraglycerol hexabenzyl, and triglycerol pentabenzyl are preferred as the glycerol ester compound. Additionally, the polyglycerol used in the polyglycerol ester compound is preferably formed by the dehydration condensation of glycerol, and has a degree of polymerization of 3 to 9.

[0164] The content of the release agent is not particularly limited. From the perspective of improving the balance between the toner's preservation and low-temperature fixing properties, and suppressing the generation of fog, it is preferably 1 part or more and 30 parts or less of styrene-acrylic resin included as a binder resin, more preferably 5 parts or more and 20 parts or less, and even more preferably 10 parts or more and 15 parts or less.

[0165] In addition, release agents can be used alone, or in combination of two or more.

[0166] (Release agent / dispersant)

[0167] Nonionic surfactants are used as release agent dispersants.

[0168] As nonionic surfactants, there are no particular limitations, but examples include polyoxyalkylene alkyl aryl ether surfactants, polyoxyalkylene styrene aryl ether surfactants, polyoxyalkylene alkyl ether surfactants, polyoxyalkylene alkenyl ether surfactants, polyoxyalkylene fatty acid ester surfactants, dehydrated sorbitol fatty acid ester surfactants, organosilicon surfactants, alkynyl alcohol surfactants, and fluorinated surfactants.

[0169] Examples of polyoxyalkylene alkylaryl ether surfactants include polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, and polyoxyethylene dodecylphenyl ether.

[0170] Examples of polyoxyalkylene stilbene aryl ether surfactants include, for example, polyoxyethylene stilbene phenyl ether.

[0171] Examples of polyoxyalkylene alkyl ether surfactants include polyoxyethylene lauryl ether, polyoxyethylene hexadecyl ether, and polyoxyethylene stearyl ether.

[0172] Examples of polyoxyalkylene ether surfactants include polyoxyethylene oil-based ethers and polyoxyethylene methylbutenyl ethers.

[0173] Examples of surfactants that are polyoxyalkylene fatty acid esters include polyoxyethylene oleate, polyoxyethylene laurate, and polyoxyethylene distearate.

[0174] Furthermore, while specific examples of the aforementioned nonionic surfactants containing polyoxyalkylene groups may include nonionic surfactants where the polyoxyalkylene group is polyoxyethylene, these are not limited to this. In this invention, among the aforementioned nonionic surfactants containing polyoxyethylene groups, nonionic surfactants in which some or all of the polyoxyethylene group is replaced by other polyoxyalkylene groups such as polyoxypropylene or polyoxybutylene can also be used.

[0175] Examples of surfactants that are surfactants of sorbitol fatty acid esters include sorbitol laurate, sorbitol monostearate, sorbitol monooleate, sorbitol sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate.

[0176] Examples of organosilicon surfactants include dimethylpolysiloxane.

[0177] Examples of alkynyl alcohol surfactants include 2,4,7,9-tetramethyl-5-decyn-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-1-hexyn-3-ol.

[0178] Examples of fluorinated surfactants include fluoroalkyl esters.

[0179] Examples of nonionic surfactants include polyethylene glycol fatty acid esters, polyethylene glycol phosphate esters, fatty acid monoglycerides, polyglycerol fatty acid esters, propylene glycol fatty acid esters, sucrose fatty acid esters, polyoxyethylene-polyoxypropylene block copolymers, polyoxyethylene-polyoxypropylene alkyl ethers, ethylene oxide derivatives of alkylphenol formaldehyde condensates, polyoxyethylene glycerol fatty acid esters, polyoxyethylene hydrogenated castor oil, polyoxyethylene dehydrated sorbitol fatty acid esters, polyoxyethylene dehydrated sorbitol fatty acid esters, fatty acid alkanolamides, and polyoxyethylene fatty acid amides.

[0180] As nonionic surfactants, polyoxyalkylene alkyl aryl ether surfactants, polyoxyalkylene styrene aryl ether surfactants, polyoxyalkylene alkyl ether surfactants, polyoxyalkylene alkenyl ether surfactants, and polyoxyalkylene fatty acid esters are particularly preferred, more preferably polyoxyalkylene alkyl aryl ether surfactants and polyoxyalkylene styrene aryl ether surfactants, and especially preferably polyoxyalkylene styrene aryl ether surfactants.

[0181] Furthermore, from the perspective of excellent improvement in the dispersibility of ester waxes, nonionic surfactants containing polyoxyalkylene groups are preferred as nonionic surfactants. The repetition number of the aforementioned polyoxyalkylene groups is preferably 10 to 20, more preferably 12 to 18. In addition, examples of polyoxyalkylene groups include polyoxyethylene, polyoxypropylene, and polyoxybutylene, among which polyoxyethylene is particularly preferred.

[0182] Examples of nonionic surfactants containing polyoxyalkylene oxides include polyoxyalkylene alkyl aryl ether surfactants, polyoxyalkylene alkyl ether surfactants, polyoxyalkylene alkenyl ether surfactants, polyoxyalkylene styrene aryl ether surfactants, and polyoxyalkylene fatty esters.

[0183] Commercially available products can also be used as nonionic surfactants. Examples of commercially available nonionic surfactants include Emulgen A-60 (polyoxyethylene (stilbene) ether, with an average addition molar number of 13 for polyoxyethylene) manufactured by Kao Corporation, Emulgen 120 (polyoxyethylene lauryl ether), Emulgen 109P (polyoxyethylene lauryl ether), Emulgen 106 (polyoxyethylene lauryl ether), Emulgen 150 (polyoxyethylene lauryl ether), Emulgen 108 (polyoxyethylene lauryl ether), and the LATEMUL PD series (polyoxyalkylene alkenyl ethers with terminal double bonds, alkenyl, epoxybutyl, and epoxyethylene groups), as well as "polyoxyethylene (20) hexadecyl ether" manufactured by Fujifilm and Koujun Pharmaceutical Co., Ltd.

[0184] Without prejudice to the purpose of the present invention, cationic, anionic, or amphoteric ionic surfactants may also be included as release agent dispersants. From the aspects of suppressing the decrease in the charged stability of the toner and suppressing the generation of haze, suppressing the decrease in the toner's resilience, and suppressing uneven gloss of the formed image, the content of ionic surfactants contained in the polymerizable monomer composition relative to the total amount of surfactant (100% by mass) is preferably 60% by mass or less, more preferably 50% by mass or less, further preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 1% by mass or less. That is, the content of nonionic surfactants contained in the polymerizable monomer composition relative to the total amount of surfactant (100% by mass) is preferably 40% by mass or more, more preferably 50% by mass or more, further preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more.

[0185] Furthermore, from the perspective of excellent dispersibility of the release agent, the molecular weight of the surfactant used as the release agent dispersant is preferably 100 to 500.

[0186] The content of the release agent dispersant is not particularly limited, but is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, and even more preferably 0.7 to 13 parts by weight, relative to 100 parts by weight of the release agent.

[0187] Furthermore, the content of the nonionic surfactant is not particularly limited, but is preferably 0.1 to 20 parts by weight, more preferably 0.4 to 15 parts by weight, and even more preferably 0.7 to 12 parts by weight, relative to 100 parts by weight of the release agent. Thus, the mass of the nonionic surfactant present on the surface of the toner particles is easily within the range of 0.1 to 500 ppm relative to the mass of the toner particles.

[0188] (Electrification control agent)

[0189] As the charge control agent contained in the above-mentioned polymerizable monomer composition, a positively charged charge control agent used to improve the charge of the toner can generally be appropriately selected, without particular limitation.

[0190] Examples of positively charged charge control agents include aniline black dyes, quaternary ammonium salts, triaminotriphenylmethane compounds and imidazole compounds, as well as positively charged charge control resins.

[0191] As the aforementioned charge control agent, from the perspectives of high compatibility with the aforementioned polymerizable monomers, ability to impart stable charge to the toner particles, and excellent charge stability, a charge control resin containing positive charge is particularly preferred.

[0192] As a positively charged control resin, a functional group copolymer can be used. Specifically, a functional group copolymer can be used, for example, a structural unit containing functional groups such as amino groups, quaternary ammonium groups, or quaternary ammonium salt groups.

[0193] In the aforementioned functionalized copolymers used as positively charged control resins, the content of functionalized structural units relative to all structural units (sometimes simply referred to as "functionalized amount" in this invention) is preferably 0.3% by mass or more and 20% by mass or less, more preferably 0.3% by mass or more and 10% by mass or less. When the functionalized amount is above the aforementioned lower limit, the charging property of the toner is improved, and haze is less likely to occur. When it is below the aforementioned upper limit, the balance between the toner's low-temperature fixing and heat-resistant storage properties is easily improved. Furthermore, when the functionalized amount is excessive, the charging stability is easily deteriorated and haze is generated. If the functionalized amount is below the aforementioned upper limit, haze is less likely to occur.

[0194] As the aforementioned functionalized copolymers, two or more functionalized copolymers with different amounts of functional groups can be combined. In coloring resin particles, when two or more functionalized copolymers with different amounts of functional groups are combined as a charge control resin, the desired charge of the toner can be imparted, and the dispersibility of the toner can be improved. Therefore, a high concentration of toner can be achieved, resulting in increased printing density. When copolymer A with a higher amount of functional groups and copolymer B with a lower amount of functional groups are used together, the following distribution is observed due to the difference in functional group amounts: copolymer B is concentrated on the relatively central side of the coloring resin particles, while copolymer A is concentrated on the near-surface side of the coloring resin particles. It is believed that because copolymer A has more functional groups than copolymer B, its charge imparting effect is stronger, and since it is concentrated on the near-surface side of the coloring resin particles, the charge of the toner is mainly influenced by copolymer A. On the other hand, copolymer B also exerts a charge imparting effect, but its effect on dispersing the toner within the coloring resin particles is stronger. It is speculated that through the action of such copolymers A and B, the toner is endowed with the desired charge, and the dispersibility of the colorant is improved.

[0195] When using two or more functional group copolymers with different amounts of functional groups as charge control agents, copolymer A, which contains 5% or more but less than 10% by mass of functional groups, and copolymer B, which contains 0.3% or more but less than 5% by mass of functional groups, are preferred.

[0196] From the perspective of imparting the desired charge to the colorant and improving the dispersibility of the colorant, the amount of functional groups in the copolymer A is preferably 5% by mass or more as a lower limit, more preferably 6% by mass or more, and preferably 10% by mass or less as an upper limit, more preferably 9% by mass or less.

[0197] From the perspective of imparting the desired charge to the colorant and improving the dispersibility of the colorant, the amount of functional groups in the above-mentioned copolymer B is preferably 0.3% by mass or more as a lower limit, more preferably 0.5% by mass or more as an upper limit, preferably less than 5% by mass, more preferably 4% by mass or less, and even more preferably 3% by mass or less as an upper limit.

[0198] On the other hand, when using a single functional group copolymer, the amount of functional groups in the functional group copolymer is preferably 0.3% by mass or more as a lower limit, more preferably 0.5% by mass or more as an upper limit, preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 3% by mass or less, even more preferably 2.5% by mass or less, and particularly preferably 2% by mass or less.

[0199] From the perspective of high compatibility with the aforementioned polymerizable monomers, the functional group-containing copolymers used as positively charged controlled resins are particularly preferred to be styrene-acrylate resins. Here, the styrene-acrylate resin is preferably a copolymer comprising two or more monomers, including aromatic vinyl monomers and (meth)acrylate monomers. Specifically, the total percentage of structural units from aromatic vinyl monomers and structural units from (meth)acrylate monomers, relative to all structural units, is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0200] Furthermore, the glass transition temperature (Tg) of the charged control resin is preferably in the range of 50°C or higher and 110°C or lower, more preferably in the range of 60°C or higher and 100°C or lower. When the glass transition temperature (Tg) of the charged control resin is within the above range, a good balance between the low-temperature fixing properties and heat-resistant preservation properties of the toner is easily achieved.

[0201] Furthermore, the weight-average molecular weight (Mw) of the charged control resin is preferably in the range of 5,000 or more and 30,000 or less, more preferably in the range of 10,000 or more and 25,000 or less. When the weight-average molecular weight (Mw) of the charged control resin is within the above range, a good balance between the low-temperature fixing properties and heat-resistant storage properties of the toner is easily achieved.

[0202] The content of the aforementioned charge control agent is not particularly limited, but is preferably 0.01 parts by weight or more and 15 parts by weight or less, more preferably 0.03 parts by weight or more and 8 parts by weight or less, relative to 100 parts by weight of the styrene-acrylic resin included as a binder. When the content of the aforementioned charge control agent is at or above the aforementioned lower limit, the generation of fog can be suppressed; on the other hand, when the content of the aforementioned charge control agent is at or below the aforementioned upper limit, printing contamination can be suppressed.

[0203] In addition, the above-mentioned charge control agents can be used alone or in combination of two or more.

[0204] (Acrylic resin containing acidic groups)

[0205] Polymerizable monomer compositions may also contain acrylic resins with acidic groups. This makes it easier to control the particle size of the colored resin particles and suppress the formation of coarse particles.

[0206] As an acrylic resin containing acidic groups, it is preferably a copolymer of at least one selected from acrylates and methacrylates with at least one selected from acrylic acid and methacrylic acid, and more preferably a copolymer of acrylates, methacrylates and acrylic acid.

[0207] Examples of (meth)acrylates include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-amyl (meth)acrylate, sec-amyl (meth)acrylate, isoamyl (meth)acrylate, neoamyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, and neohexyl (meth)acrylate. Alkyl methacrylates, including sec-hexyl methacrylate, tert-hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, methoxy polyethylene glycol (meth)acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, glycidyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether. Alkyl methacrylates are particularly preferred.

[0208] The acrylate used in the above-mentioned acrylic resin containing acidic groups is preferably selected from at least one of ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and n-butyl acrylate, and more preferably from at least one of ethyl acrylate and n-butyl methacrylate. The methacrylate used in the above-mentioned acrylic resin containing acidic groups is preferably selected from at least one of methyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate, and more preferably methyl methacrylate.

[0209] In the above-mentioned acrylic resin containing acidic groups, from the aspects of high compatibility with the above-mentioned polymerizable monomers, easy control of the particle size of the colored resin particles, and easy suppression of the formation of coarse particles, the ratio of (meth)acrylic acid used in the synthesis of the above-mentioned acrylic resin containing acidic groups to the total amount of (meth)acrylate and (meth)acrylic acid in 100% by mass is preferably 0.05 to 1 by mass, more preferably 0.1 to 0.6 by mass, and even more preferably 0.3 to 0.5 by mass.

[0210] From the perspectives of high compatibility with the aforementioned polymerizable monomers, ease of control over the particle size of the colored resin particles, and ease of suppressing the formation of coarse particles, the copolymer of the aforementioned acrylic resin containing acidic groups is preferably a copolymer containing 50.0% or more methyl methacrylate monomers, relative to 100% by mass of monomers used in the synthesis of the copolymer. The aforementioned acrylic resin containing acidic groups is more preferably a copolymer comprising 50.0 to 99.9% by mass of methyl methacrylate and 0.1 to 5.0% by mass of (meth)acrylic acid monomers, further preferably a copolymer comprising 50.0 to 99.0% by mass of methyl methacrylate and 0.1 to 5.0% by mass of (meth)acrylic acid monomers, even more preferably a copolymer comprising 50.0 to 98.0% by mass of methyl methacrylate, 1.0 to 5.0% by mass of (meth)acrylic acid alkyl esters different from methyl methacrylate and 0.1 to 5.0% by mass of (meth)acrylic acid monomers, particularly preferably a copolymer comprising 50.0 to 98.0% by mass of methyl methacrylate, 1.0 to 5.0% by mass of (meth)acrylic acid alkyl esters different from methyl methacrylate and 0.2 to 3.0% by mass of (meth)acrylic acid monomers.

[0211] As an alkyl acrylate (meth)acrylate that is different from methyl methacrylate, it is preferred to be at least one selected from ethyl acrylate and butyl acrylate from the perspective of being able to control the glass transition point.

[0212] Furthermore, the aforementioned acrylic resin containing acidic groups may contain a small amount of monomer units derived from monomers different from both (meth)acrylate and (meth)acrylic acid. From the perspective of easily controlling the particle size of the colored resin particles and easily suppressing the formation of coarse particles, the content of the aforementioned other monomers is preferably 30% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, and most preferably does not contain the aforementioned other monomers, out of a total of 100% by mass of monomers used in the synthesis of the aforementioned acrylic resin containing acidic groups.

[0213] Other monomers mentioned above include, for example, halogenated aromatic vinyl monomers, aromatic vinyl monomers containing polar groups, vinyl carboxylic acid ester monomers, halogenated vinyl monomers, unsymmetrical dihalogenated vinyl monomers, vinylpyridine, olefinically unsaturated carboxylic acid monomers, allyl glycidyl ethers, aromatic vinyl monomers, monoolefin monomers, diene monomers, etc.

[0214] The acid value of the aforementioned acrylic resin containing acidic groups is preferably 0.5–7.0 mgKOH / g, more preferably 1.0–5.0 mgKOH / g, and even more preferably 1.5–3.0 mgKOH / g. When the acid value of the aforementioned acrylic resin containing acidic groups is within the above range, it has a strong effect on improving the heat resistance, low-temperature fixing, and printing durability of the toner. In addition, it also has a strong effect on suppressing the formation of coarse particles.

[0215] The weight-average molecular weight (Mw) of the aforementioned acrylic resin containing acidic groups is preferably 8,000 to 45,000, more preferably 9,000 to 45,000, and even more preferably 10,000 to 40,000. When the weight-average molecular weight (Mw) of the aforementioned acrylic resin containing acidic groups is above the lower limit, the heat resistance and durability of the toner can be improved; when the weight-average molecular weight (Mw) of the aforementioned acrylic resin containing acidic groups is below the upper limit, the rise in the fixing temperature of the toner can be suppressed.

[0216] The glass transition temperature (Tg) of the above-mentioned acrylic resin containing acidic groups is preferably 60-95°C, more preferably 65-90°C, and even more preferably 70-80°C.

[0217] By setting the glass transition temperature of the aforementioned acrylic resin containing acidic groups to the lower limit or above, the heat resistance of the toner can be improved; and by setting the glass transition temperature of the aforementioned acrylic resin containing acidic groups to the upper limit or below, the low-temperature fixing properties of the toner can be improved.

[0218] The aforementioned acrylic resins containing acidic groups can be commercially available products and can be manufactured by polymerizing monomers containing the aforementioned monomers using known methods such as solution polymerization, aqueous solution polymerization, ionic polymerization, high-temperature and high-pressure polymerization, and suspension polymerization.

[0219] Furthermore, when the aforementioned acrylic resin containing acidic groups is a copolymer, the copolymer can be any one of a random copolymer, a block copolymer, or a graft copolymer, preferably a random copolymer.

[0220] Furthermore, from the perspective of improving solubility, the aforementioned acrylic resins containing acidic groups are preferably pulverized more finely.

[0221] The content of the acid-containing acrylic resin is preferably 0.5 to 2.5 parts by mass, more preferably 0.8 to 2.2 parts by mass, and even more preferably 1.0 to 2.0 parts by mass, relative to 100 parts by mass of the styrene-acrylic resin included as a binder. By having the content of the acid-containing acrylic resin at or above the lower limit, it is easier to control the particle size of the coloring resin particles, and furthermore, it is easier to suppress the formation of coarse particles. On the other hand, by having the content of the acid-containing acrylic resin at or below the upper limit, it is possible to suppress the rise in the fixing temperature of the toner.

[0222] (Styrene-based thermoplastic elastomers)

[0223] The polymerizable monomer composition may also contain styrene-based thermoplastic elastomers. Since styrene-based thermoplastic elastomers can improve the dispersibility of release agents, their presence helps maintain the heat resistance temperature of the toner and improves its fixing properties. Here, styrene-based thermoplastic elastomers refer to random, block, or graft copolymers of styrene monomers and at least one other monomer selected from monoolefins and dienes capable of copolymerizing with styrene monomers, as well as hydrogenates of these copolymers.

[0224] Examples of styrene-based thermoplastic elastomers used in this invention include, for example, styrene-butadiene-styrene block copolymers, styrene-butadiene block copolymers, styrene-isoprene-styrene block copolymers, styrene-isoprene block copolymers, styrene-butadiene-isoprene-styrene block copolymers, and their hydrides; styrene-ethylene-butene-styrene block copolymers, styrene-ethylene-propylene-styrene block copolymers, and styrene-ethylene-ethylene-propylene-styrene block copolymers.

[0225] Among these styrene-based thermoplastic elastomers, from the viewpoint of optimizing the balance between toner preservation and low-temperature fixing properties, styrene-isoprene-styrene block copolymers are preferred.

[0226] The styrene unit content in the aforementioned styrene-based thermoplastic elastomer is preferably 15-70% by mass, more preferably 15-60% by mass, and even more preferably 20-40% by mass. When the styrene content is above the lower limit mentioned above, the proportion of hydrocarbon units will not be too high, and the toner used for fixing is less likely to peel off from the fixing surface, thus suppressing a decrease in fixing performance. On the other hand, when the styrene content is below the upper limit mentioned above, the compatibility with the binder resin will not be too high, and a decrease in the toner's retention properties will be suppressed.

[0227] The weight-average molecular weight (Mw) of the above-mentioned styrene-based thermoplastic elastomer is not particularly limited, but from the perspective of maintaining the heat resistance temperature of the toner and improving the fixing properties of the toner, it is preferably 50,000 to 350,000, and more preferably 80,000 to 250,000.

[0228] Commercially available products can be used as the aforementioned styrene-based thermoplastic elastomers. Examples of commercially available styrene-based thermoplastic elastomers include the Quintac (registered trademark) series manufactured by Zeon Corporation of Japan and the SEPTON (registered trademark) series manufactured by Kuraray Corporation.

[0229] The content of the styrene-based thermoplastic elastomer is not particularly limited, but it is preferably used at a ratio of 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, and even more preferably 2 to 6 parts by weight, relative to 100 parts by weight of styrene-acrylic resin included as a binding resin.

[0230] In addition, the above-mentioned styrene-based thermoplastic elastomers can be used alone or in combination of two or more.

[0231] (Other additives)

[0232] The above-described polymerizable monomer composition may contain other additives as needed, without prejudice to the purpose of the present invention.

[0233] As other additives, molecular weight regulators, for example, can be preferred.

[0234] As a molecular weight regulator, there are no particular limitations as long as it is a molecular weight regulator commonly used as a colorant. Examples include thiols such as tert-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2,4,6,6-pentamethylheptane-4-thiol; and dithiuram disulfide such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N,N'-dimethyl-N,N'-diphenylthiuram disulfide, and N,N'-di(octadecyl)-N,N'-diisopropylthiuram disulfide.

[0235] The aforementioned molecular weight regulators can be used alone or in combination of two or more.

[0236] When the above-mentioned polymerizable monomer composition contains a molecular weight regulator, the content of the molecular weight regulator can be appropriately adjusted in a way that allows the bonding resin to achieve the desired molecular weight. There is no particular limitation, but it is usually 0.01 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the above-mentioned monovinyl monomer, or it can be 0.1 parts by mass or more and 5 parts by mass or less.

[0237] Furthermore, the aforementioned polymerizable monomer composition may also contain a polymerization initiator, which may be added to the dispersion obtained in the droplet formation step described later. From the perspective of easily controlling the molecular weight of the polymer, it is preferable to add the polymerization initiator to the dispersion in which the polymerizable monomer composition is dispersed in an aqueous solvent during the droplet formation step described later.

[0238] (A-2) The suspension process (droplet formation process) to obtain the suspension.

[0239] Next, the polymerizable monomer composition is dispersed in an aqueous medium containing a dispersion stabilizer, and a polymerization initiator is added to form droplets of the polymerizable monomer composition. The polymerization initiator can be added after the polymerizable monomer composition is dispersed in the aqueous medium and before droplet formation, as described above, or it can be added to the polymerizable monomer composition before it is dispersed in the aqueous medium.

[0240] There are no particular limitations on the method of droplet formation. For example, it can be carried out using a device that can strongly stir, such as a (pipeline type) emulsifier / disperser (manufactured by Taihei Kiko Co., Ltd., trade name: Milder) or a high-speed emulsifier / disperser (manufactured by Primix Co., Ltd., trade name: TK homogenizer MARKII type).

[0241] Examples of polymerization initiators include: persulfates such as potassium persulfate and ammonium persulfate; azo compounds such as 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), 2,2'-azobis(2-amidinylpropane) dihydrochloride, 2,2'-azobis(2,4-dimethylpentanonitrile), and 2,2'-azobisisobutyronitrile; and organic peroxides such as di-tert-butyl peroxide, benzoyl peroxide, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide-2-ethylbutyrate, tert-hexyl peroxide-2-ethylbutyrate, diisopropyl peroxide dicarbonate, di-tert-butyl peroxide-isophthalate, and tert-butyl peroxide-isobutyrate. Among these, organic peroxides are preferred from the perspective of reducing residual polymerizable monomers and obtaining toners with excellent printability. Among organic peroxides, peroxide esters are preferred from the perspective of good initiator efficiency and the ability to reduce residual polymerizable monomers, and non-aromatic peroxide esters, i.e., peroxide esters without aromatic rings, are more preferred.

[0242] These polymerization initiators can be used individually or in combination of two or more.

[0243] The amount of polymerization initiator added in the polymerization reaction of the polymerizable monomer composition is preferably 0.1 to 20 parts by mass relative to 100 parts by mass of the monovinyl monomer, more preferably 0.3 to 15 parts by mass, and particularly preferably 1 to 10 parts by mass.

[0244] In this invention, the aqueous medium refers to a medium whose main component is water.

[0245] In this invention, it is preferable that the aqueous medium contains a dispersing stabilizer. Examples of dispersing stabilizers include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate, and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as alumina and titanium oxide; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and iron hydroxide; inorganic compounds such as silica; water-soluble polymers such as polyvinyl alcohol, methylcellulose, and gelatin; anionic surfactants; nonionic surfactants; and amphoteric surfactants. One or more of these dispersing stabilizers can be used.

[0246] Among the aforementioned dispersants and stabilizers, inorganic compounds are preferred, and colloids of metal hydroxides that are poorly soluble in water are particularly preferred as the aqueous medium containing the dispersant and stabilizer. By using inorganic compounds, especially colloids of metal hydroxides that are poorly soluble in water, the particle size distribution of the coloring resin particles can be narrowed. Furthermore, the amount of dispersant and stabilizer residue after washing can be reduced. Therefore, the resulting toner can vividly reproduce images and does not deteriorate environmental stability.

[0247] (A-3) Polymerization process

[0248] After droplet formation of the polymerizable monomer composition as described in (A-2) above, colored resin particles are formed by subjecting the polymerizable monomer composition to a polymerization reaction in the presence of a polymerization initiator. Specifically, an aqueous dispersion medium containing droplets of the polymerizable monomer composition is heated to initiate polymerization, thereby preparing an aqueous dispersion of colored resin particles.

[0249] The heating conditions described above are not particularly limited, but the heating temperature is preferably 50°C or higher, and more preferably 60–95°C. Furthermore, the heating time is preferably 1 to 20 hours, and more preferably 2 to 15 hours.

[0250] Coloring resin particles can be used directly as a toner, or with the addition of external additives and used as a toner. Preferably, these coloring resin particles are used as the core layer of so-called core-shell (or "capsule-type") coloring resin particles. Core-shell type coloring resin particles have a structure in which the outer side of the core layer is coated with a shell layer formed of a material different from the core layer. By coating the core layer, which is made of a material with a low softening point, with a material having a higher softening point, a good balance can be achieved in improving the low-temperature fixing and preservation properties of the toner.

[0251] The method for manufacturing core-shell type colored resin particles using the aforementioned colored resin particles is not particularly limited and can be manufactured using conventionally known methods. From the perspective of manufacturing efficiency, in-situ polymerization and phase separation methods are preferred.

[0252] The following describes a method for manufacturing core-shell colored resin particles using in-situ polymerization.

[0253] In an aqueous medium containing dispersed colored resin particles, a polymerizable monomer (shell polymerizable monomer) for forming a shell and a polymerization initiator are added, and polymerization is carried out to obtain core-shell type colored resin particles.

[0254] As the shell polymerizable monomer, the same monomers as those described above can be used. Among them, it is preferable to use monomers such as styrene, acrylonitrile, and methyl methacrylate, which can produce polymers with a Tg greater than 80°C, either alone or in combination of two or more.

[0255] Examples of polymerization initiators used in the polymerization of shell-type polymerizable monomers include persulfate metal salts such as potassium persulfate and ammonium persulfate; and water-soluble polymerization initiators such as azo initiators like 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide) and 2,2'-azobis(2-methyl-N-(1,1-bis(hydroxymethyl)-2-hydroxyethyl)propionamide). These can be used individually or in combination of two or more. The amount of polymerization initiator relative to 100 parts by weight of shell-type polymerizable monomer is preferably 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight.

[0256] The polymerization temperature of the shell layer is preferably 50°C or higher, more preferably 60–95°C. Furthermore, the polymerization reaction time is preferably 1 hour to 20 hours, more preferably 2 hours to 15 hours.

[0257] (A-4) Washing, filtering, dehydration and drying processes

[0258] Preferably, after polymerization, the aqueous dispersion of colored resin particles obtained by polymerization is subjected to repeated filtration, washing to remove the dispersant stabilizer, dehydration and drying operations according to conventional methods as needed.

[0259] As a cleaning method described above, when using an inorganic compound as a dispersion stabilizer, it is preferable to dissolve and remove the dispersion stabilizer in water by adding an acid or alkali to the aqueous dispersion of the coloring resin particles. When using a colloid of an inorganic hydroxide that is poorly soluble in water as a dispersion stabilizer, it is preferable to add an acid to adjust the pH of the aqueous dispersion of the coloring resin particles to 6.5 or below. As the added acid, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, as well as organic acids such as formic acid and acetic acid, can be used. From the perspective of high removal efficiency and low burden on manufacturing equipment, sulfuric acid is particularly preferred.

[0260] The coloring resin particles are preferably washed until the conductivity of the filtrate is 300 μS / cm or less, more preferably 200 μS / cm or less, and even more preferably 50 μS / cm or less. This ensures that the conductivity of the extract of the colorant is within the preferred range described later.

[0261] In addition, the aforementioned filtrate refers to the filtrate obtained from a series of cleaning processes, specifically the filtrate just before the cleaning process is completed.

[0262] Dehydration and filtration methods can be various well-known methods, without particular limitations. Examples include centrifugal filtration, vacuum filtration, and pressure filtration. Furthermore, drying methods are also not particularly limited and various methods can be used.

[0263] (B) Crushing method

[0264] When manufacturing colored resin particles using a pulverizing method, the process is carried out, for example, as follows.

[0265] First, binder resin, colorant, release agent, release agent dispersant, charge control agent, and other additives such as acid-containing acrylic resins and styrene thermoplastic elastomers are mixed using a mixer such as a ball mill, V-type mixer, FM Mixer, high-speed dissolving machine, internal mixer, or Forberg mixer. Next, the mixture is kneaded while heated using a pressure kneader, biaxial extrusion mixer, or roller mill. The resulting mixture is then coarsely pulverized using a hammer mill, milling mill, or roller mill. Finally, it is finely pulverized using a jet mill or high-speed rotary mill, and then classified into desired particle sizes using a classifier such as an air classifier or air classifier, thereby obtaining colored resin particles produced by the pulverization method.

[0266] Furthermore, the binder resin, colorant, release agent, release agent dispersant, charge control agent, and, as needed, acid-containing acrylic resin or styrene thermoplastic elastomer used in the pulverization method can be any of the substances mentioned in the suspension polymerization method described in (A). Moreover, the colored resin particles obtained by the pulverization method can be processed into core-shell colored resin particles using methods such as in-situ polymerization, similar to the colored resin particles obtained by the suspension polymerization method described in (A).

[0267] 2. Colored resin particles

[0268] The coloring resin particles contained in the colorant of the present invention can be obtained by the manufacturing methods described above, such as (A) suspension polymerization or (B) pulverization.

[0269] The following describes the coloring resin particles contained in the toner. Furthermore, the coloring resin particles described below include both core-shell and non-core-shell type coloring resin particles.

[0270] The colorant of the present invention contains coloring resin particles comprising a binding resin, a colorant, a release agent, a release agent dispersant, and a charge control agent. It may also contain other additives such as acrylic resins containing acidic groups and styrene thermoplastic elastomers, as needed.

[0271] As a binding resin, it comprises at least a styrene-acrylic resin polymerized from the polymerizable monomers used in the suspension polymerization method described above (A) and the aforementioned polyester resin. In the toner of the present invention, the styrene-acrylic resin and the polyester resin included as binding resins do not crosslink through covalent bonds, but rather act between the resins through weaker forces such as π-π interactions or hydrogen bonds. Therefore, it is possible to balance the previously trade-off between low-temperature fixing performance and heat-induced degradation resistance.

[0272] In addition, the acid value of the styrene-acrylic resin included as a binding resin is usually less than 0.5 mg KOH / g, or it can be 0 mg KOH / g.

[0273] Without prejudice to the purpose of the present invention, the colorant of the present invention can use resins such as polystyrene and epoxy resin, which have been widely used in colorants, in addition to the styrene-acrylic resin and polyester resin mentioned above, as the binding resin.

[0274] In the toner of the present invention, the total amount of styrene-acrylic resin and polyester resin relative to 100% by mass of binder resin is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 99% by mass or more, and particularly preferably 100% by mass.

[0275] Regarding the colorants, release agents, release agent dispersants, charge control agents, acrylic resins containing acidic groups, and styrene thermoplastic elastomers contained in the colored resin particles, as described in the suspension polymerization method (A) above.

[0276] 3. External additives

[0277] Regarding the colorant of the present invention, the coloring resin particles can be used directly as the colorant. However, from the viewpoint of adjusting the charge, flowability and storage properties of the colorant, the above-mentioned coloring resin particles can also be mixed and stirred together with external additives and subjected to external additive treatment, so that the external additives adhere to the surface of the coloring resin particles, thus serving as the colorant of the present invention.

[0278] There are no particular limitations on the mixer used for external additive processing, as long as it is a mixing device that can make the external additives adhere to the surface of the coloring resin particles. Mixers capable of mixing and stirring, such as FM Mixer (trade name, manufactured by Nippon Kogyo Kogyo Co., Ltd.), Super Mixer (trade name, manufactured by Kawada Seisakusho Co., Ltd.), QMixer (trade name, manufactured by Nippon Kogyo Kogyo Co., Ltd.), Mechanical Fusion System (trade name, manufactured by Hosokawa Micron Co., Ltd.), and Mechano Mill (trade name, manufactured by Okada Seiko Co., Ltd.), can be used for external additive processing.

[0279] Examples of external additives include inorganic particles such as silica, titanium dioxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, cerium oxide, barium titanate, and strontium titanate; and organic particles such as polymethyl methacrylate resin, silicone resin, and melamine resin. Among these, inorganic particles are preferred, and among inorganic particles, at least one particle selected from silica particles and titanium dioxide particles is preferred, with silica particles being particularly preferred.

[0280] In addition, these external additives can be used individually, or preferably in combination of two or more.

[0281] In the toner of the present invention, the external additive is typically used at a ratio of 0.05 to 6 parts by weight relative to 100 parts by weight of coloring resin particles, preferably at a ratio of 0.2 to 5 parts by weight. By using an external additive content of 0.05 parts by weight or more, the occurrence of transfer residue can be suppressed; by using an external additive content of 6 parts by weight or less, the generation of haze can be suppressed.

[0282] 4. Toner particles

[0283] The toner of the present invention is an aggregate of "toner particles". Each toner particle may consist only of coloring resin particles, or it may include coloring resin particles and external additives attached to the surface of the coloring resin particles.

[0284] In the toner of the present invention, the mass of the nonionic surfactant present on the surface of the toner particles is 0.1 to 500 ppm, particularly preferably 30 to 500 ppm, relative to the mass of the toner particles. The mass of the nonionic surfactant present on the surface of the toner particles is an indicator of the amount of nonionic surfactant added as a release agent dispersant when manufacturing the coloring resin particles. The lower limit of the mass of the nonionic surfactant present on the surface of the toner particles is 0.1 ppm or more, preferably 20 ppm or more, more preferably 30 ppm or more, and even more preferably 40 ppm or more. If the mass of the nonionic surfactant present on the surface of the toner particles is above the above-mentioned lower limit, a sufficient amount of nonionic surfactant is added, the dispersibility of the release agent is good, and therefore the melt viscosity of the toner decreases and the low-temperature fixing property of the toner is improved. On the other hand, if the mass of the nonionic surfactant present on the surface of the toner particles is 500 ppm or less, the deterioration of the toner properties caused by the surfactant present on the surface of the toner particles is suppressed. Specifically, since the deterioration of the charge stability is suppressed, it is less likely to generate haze. Furthermore, due to the suppression of adhesion, heat resistance and preservation are good. Consequently, the exudation of the release agent is suppressed. The mass of the nonionic surfactant present on the surface of the toner particles is preferably less than 400 ppm, more preferably less than 300 ppm, even more preferably less than 200 ppm, even more preferably less than 100 ppm, and particularly preferably less than 90 ppm.

[0285] The mass of surfactant present on the surface of toner particles can be determined using an extract of the toner. The toner extract is a liquid obtained by adding toner to an aqueous medium and stirring, thereby extracting the water-soluble components present on the surface of the toner particles into the aqueous medium. A mixture of alcohol and water is preferably used as the aqueous medium.

[0286] For the extract of the toner used to determine the mass of the surfactant present on the surface of the toner particles, it can be obtained specifically by dispersing 10 g of the toner in 100 mL of a mixed solvent of IPA (isopropanol) and ion-exchanged water (IPA / ion-exchanged water = 80 / 20 (volume ratio)), stirring at 50 °C for 30 minutes, and then separating the liquid components.

[0287] When the extract of a toner contains both nonionic and ionic surfactants, the extract of the toner is treated with anion exchange resin and cation exchange resin to remove the ionic surfactants from the extract when only the mass of the nonionic surfactants is measured. The amount of surfactant in the treated extract of the toner is then measured.

[0288] The quality of surfactants contained in the extract of colorants can be determined by selecting an appropriate method from known methods such as LC / MS (liquid chromatography-mass analysis), IC (ion exchange chromatography), and GC / MS (gas chromatography-mass analysis), depending on the type of surfactant.

[0289] The mass of the nonionic surfactant used in this invention can be determined by LC / MS (liquid chromatography-mass analysis). Specific determination methods using LC / MS are described in the examples below.

[0290] From the perspectives of suppressing the decrease in the charge stability of the toner, suppressing the generation of fog, suppressing the decrease in the preservation of the toner, and suppressing the uneven gloss of the formed image, the mass of the ionic surfactant present on the surface of the toner particles is preferably 40 ppm or less, more preferably 30 ppm or less, even more preferably 20 ppm or less, even more preferably 10 ppm or less, and particularly preferably 1 ppm or less.

[0291] The volume average particle size (Dv) of the toner particles in the toner of the present invention is preferably 3 to 15 μm, more preferably 4 to 12 μm. When Dv is at or above the lower limit of the above-mentioned value, the fluidity of the toner can be improved, and the deterioration of transferability and the reduction of image density can be suppressed. When Dv is at or below the upper limit of the above-mentioned value, the reduction of image resolution can be suppressed.

[0292] The ratio of the volume average particle size (Dv) to the number average particle size (Dp) of the toner particles, i.e., the particle size distribution (Dv / Dp), is preferably 1.0 or more and less than 1.3, more preferably 1.0 or more and less than 1.2. By having Dv / Dp less than 1.3, the reduction in transferability, image density, and resolution can be suppressed.

[0293] In addition, the volume average particle size and number average particle size of the toner particles can be measured using, for example, a particle size distribution measuring device (manufactured by Beckman Coulter, trade name: MULTISIZER).

[0294] From the viewpoint of image reproducibility, the average roundness of the toner particles is preferably 0.96 to 1.00, more preferably 0.97 to 1.00, and even more preferably 0.98 to 1.00.

[0295] By ensuring that the average sphericity of the toner particles is above the aforementioned lower limit, the reproducibility of fine lines in printing can be improved. An average sphericity of 1 or less is considered to be 1 when the test sample is a perfectly spherical object.

[0296] In this invention, roundness is the value of the circumference of a circle having the same projected area as the particle image divided by the circumference of the particle's projected image. Average roundness is an indicator of the unevenness of the measured sample surface and can be used as a convenient method for quantitatively representing the shape of particles. The more complex the surface shape of the measured sample, the smaller the average roundness value.

[0297] The roundness of toner particles can be determined, for example, by using an aqueous solution containing dispersed toner particles as a sample solution, and taking a projected image of the toner particles in the sample solution using a flow-through particle image analyzer (e.g., Sysmex Corporation, trade name: FPIA-2100, etc.). Based on this projected image, the circumference of a circle with the same projected area as the particle and the circumference of the particle's projected image are measured and calculated using the following formula 1. The average roundness is the average of the roundness of each toner particle contained in the sample solution.

[0298] Formula 1

[0299] (Circularity) = (Circumference of a circle with the same projected area as the particle) / (Circumference of the particle's projected image)

[0300] Furthermore, since the volume average particle size (Dv), number average particle size (Dp), and average roundness of the toner particles do not show significant differences due to the presence or absence of external additives, the values ​​of volume average particle size (Dv), number average particle size (Dp), and average roundness can be considered the same in toner particles containing external additives and in coloring resin particles without external additives.

[0301] In the toner of the present invention, from the perspective of suppressing the generation of fog, the conductivity of the toner extract is preferably 50 μS / cm or less, more preferably 40 μS / cm or less, and even more preferably 30 μS / cm or less. The conductivity of the toner extract can be used as an indicator of the degree of cleaning. The weaker the cleaning, the more dispersant stabilizer remains in the toner. Since dispersant stabilizers usually contain ionic components, the more dispersant stabilizer remains in the toner, the higher the conductivity of the toner extract.

[0302] In addition, the extract of the toner used in the conductivity determination can be obtained specifically by dispersing 10g of the toner in a mixed solvent of 100mL of IPA and ion-exchanged water (IPA / ion-exchanged water = 80 / 20 (volume ratio)), stirring at 50°C for 30 minutes, and then separating the liquid components.

[0303] In addition, the toner of the present invention can be used as a single-component developer consisting only of toner particles, or it can be further mixed and stirred with carrier particles to be used as a two-component developer.

[0304] 5. Toner Set

[0305] The toner set of the present invention is a color toner set containing positively charged toners for electrostatic image development of multiple colors, including at least yellow toner, magenta toner and cyan toner as positively charged toners for electrostatic image development of the aforementioned multiple colors, and all of the positively charged toners for electrostatic image development of the aforementioned multiple colors are positively charged toners for electrostatic image development of the present invention.

[0306] That is, the toner group of the present invention is a toner group that combines the toners of the present invention described above.

[0307] In multi-color images (sometimes simply referred to as "multi-color images" in this invention) formed using the toner set of the present invention, toner layer peeling is less likely to occur. The reason for this is speculated as follows.

[0308] In the toner group of the present invention, each toner constituting the toner group contains a combination of styrene-acrylic resin and polyester resin as a binder resin. Compared with the case where the binder resin is composed only of styrene-acrylic resin, the melt viscosity is lower, thus facilitating melting. Furthermore, each toner contains ester wax as a release agent and a specific amount of nonionic surfactant as a release agent dispersant. The ester wax in the coloring resin particles has excellent dispersibility, resulting in high plasticizing effect and facilitating melting. Since each toner constituting the toner group of the present invention is a toner that easily melts, adhesion of each toner layer is easy when forming a multicolor image using the toner group of the present invention. Therefore, peeling of the toner layer is suppressed, and multilayer fixing of the toner layer is good. Furthermore, peeling of the toner layer includes, for example, peeling at the interface between the toner layer and the paper surface, peeling between toner layers, and peeling within the toner layer. Furthermore, when at least one toner in the toner group contains only a hydrocarbon-based wax as a release agent, the compatibility between the binder resin and the release agent is too high. During toner fixing, the release agent easily seeps to the surface of the toner particles. As a result, interfacial delamination easily occurs between the toner particles forming the toner layer, thus easily leading to delamination within the toner layer.

[0309] Furthermore, the toner group according to the present invention can form multicolor images with excellent gloss uniformity. The reason for this is speculated as follows.

[0310] Each toner constituting the toner group of the present invention uses ester wax as a release agent, thereby slowing down the crystallization rate of the release agent during rapid cooling after toner fixing. Therefore, uneven gloss is less likely to occur in the toner layers formed using the toner group of the present invention. On the other hand, in multicolor images formed using the toner group, the overall thickness of the toner layer increases due to the stacking of multiple toner layers. When fixing the multicolor image on the recording material, uneven melting of the toner layer can cause unevenness at the interface, resulting in uneven gloss. In contrast, each toner constituting the toner group of the present invention, as described above, is a toner that melts easily. Therefore, melting of each toner layer is easy during fixing, resulting in high uniformity of melting of the toner layer and less unevenness at the interface. Therefore, multicolor images formed using the toner group of the present invention exhibit excellent gloss uniformity.

[0311] In addition to the basic color toners—yellow, cyan, and magenta—the colorant group of the present invention may also include yellow, cyan, or magenta toners with different color elements such as hue, color density, brightness, or vividness, and may further include black toners. Even if the colorant group of the present invention includes toners different from the basic color toners—yellow, cyan, or magenta—all the toners constituting the colorant group are still the toners of the present invention as described above.

[0312] Furthermore, the toners contained in the toner group of the present invention are typically toners that present different colors to each other.

[0313] 6. Image Formation Methods

[0314] The toner set of the present invention is typically a color toner set for electrostatic image development used to form a panchromatic image in an electrostatic image development method.

[0315] The methods for forming full-color images using electrostatic image development can be broadly categorized into the following two types based on the different transfer processes.

[0316] (1) The original image is color separated to obtain the data of each color component. Based on the data of each color component, a single toner image of multiple colors is formed. These images are then transferred sequentially to a transfer medium. After color overlap is performed on the transfer medium to form a full-color image, the full-color image is transferred from the transfer medium to the recording material.

[0317] (2) Perform color separation on the original image to obtain data of each color component, form a single toner image of multiple colors based on the data of each color component, transfer them sequentially to a recording material, and perform color overlay on the recording material to form a full-color image.

[0318] According to the toner group of the present invention, multicolor images with excellent gloss uniformity and resistance to peeling of the toner layer can be formed in any of the above-described methods.

[0319] Furthermore, this invention includes the following two image formation methods. The former is a method of color overlay on a transfer medium, and the latter is a method of color overlay on a recording material.

[0320] The first method is a method for forming an image using a full-color printer via electrostatic development using the toner set of the present invention. It includes a step of developing a primary color image formed by a first toner, i.e., a first image (first image development step), a step of developing primary color images of various colors formed by a second toner, i.e., a second image (second image development step), a step of transferring the first image onto a transfer medium and then transferring the second image to form a multi-color image on the transfer medium (color overlay step on transfer medium), a step of transferring the multi-color image formed on the transfer medium onto a recording material (multi-color image transfer step), and a step of fixing the multi-color image transferred onto the recording material onto the recording material (fixing step).

[0321] The second method is a method for forming an image using the toner set of the present invention via a full-color printer by electrostatic development. It includes a step of developing a primary color image formed by a first toner, i.e., a first image, (first image development step), a step of developing primary color images of various colors formed by a second toner, i.e., a second image, (second image development step), a step of transferring the first image onto a recording material and then transferring the second image, thereby forming a multi-color image on the recording material (color overlay step on the recording material), and a step of fixing the multi-color image formed on the recording material onto the recording material (fixing step).

[0322] In addition, in this invention, "primary color" is the color obtained when printing using various color toners alone, "secondary color" is the color obtained by overlaying the primary toner images of two colors, and "multicolor" is the color that can be obtained by overlaying the primary toner images of multiple colors.

[0323] Furthermore, in this invention, the term "toner image" as it is literally means an image formed by toner, and is used in particular when it is desired to emphasize, as a visual image, the distribution of toner that matches the image to be reproduced on the image holding surface such as a photosensitive drum, transfer medium, or recording material.

[0324] Furthermore, in this invention, "starting color" refers to the color of the primary toner image that is first transferred to the transfer receiving material when multiple toner developing machines are used to form primary toner images of various colors, and these images are sequentially transferred to a transfer receiving material (recording material or transfer medium) to form a full-color image by color overlay on the transfer receiving material.

[0325] Furthermore, in this invention, "initial developing machine" refers to a developing machine that develops the original toner image of the initial color. When multiple toner developing machines are arranged in series along the transport path of the transfer receiving material (recording material or transfer medium) within the developing apparatus, the developing machine that the transfer receiving material first encounters in the transport path is the "initial developing machine".

[0326] The toner set of the present invention is preferably applied to the following printing method: using primary toners of various colors such as yellow toner, cyan toner, and magenta toner, developing the electrostatic latent image corresponding to each primary color, producing each primary toner image on a developing machine, and sequentially transferring each primary toner image to a transfer receiving material selected from recording material and transfer medium, thereby performing color overlay on the transfer receiving material to form a full-color image.

[0327] Here, when color overlap is performed on the recording material, each primary toner image is transferred to the recording material via an intermediate transfer process from the toner image forming surface of the developing machine to the transfer medium, or directly transferred to the recording material in sequence, to form a full-color image containing multiple colors on the recording material.

[0328] On the other hand, when color overlap is performed on the transfer medium, each primary toner image is transferred from the toner image forming surface of the developing machine to other prior transfer media via an intermediate transfer process, or directly transferred sequentially onto a transfer medium. After forming a multi-color image on the transfer medium, the multi-color image on the transfer medium is transferred to other subsequent transfer media via an intermediate transfer process, or directly transferred onto the recording material.

[0329] In this invention, one of the toners in the toner group is used as a first toner, and the others are used as second toners. The first toner is the primary toner that is first transferred to the transfer receiving material during the color overlay process on a transfer receiving material selected from recording materials and transfer media. The second toner is the primary toner that is transferred a second or subsequent time during the color overlay process on the transfer receiving material.

[0330] The first colorant is typically selected from yellow, cyan, and magenta colorants, while the second colorant is typically selected from yellow, cyan, magenta, and black colorants. Furthermore, the various colorants usually produce different colors from each other.

[0331] Examples of transfer media for color overlay include intermediate transfer belts and intermediate transfer rollers.

[0332] In addition to ordinary paper and other recording papers, other recording materials include coated paper, art paper, and OHP film, without any particular restrictions.

[0333] As an image forming apparatus capable of performing the above-described operational steps, a full-color printer can be used, for example, in which multiple developing machines corresponding to various colors of toner contained in a toner set are arranged in series. The primary color images (color-separated images) of various colors generated in each developing machine are transferred sequentially from each developing machine, either directly or via a transfer medium, onto a recording material, where a multi-color image containing secondary colors or more is formed. This is a type of printer with a so-called tandem configuration.

[0334] Figure 1 This figure schematically illustrates an example of the structure of an image forming apparatus to which the toner group of the present invention can be applied. Furthermore, the image forming method of the present invention is not limited to the illustrated image forming method. Additionally, the structure, size, and shape of the materials used in the method of the present invention are not limited to the structures, sizes, and shapes of the various materials shown in the figure.

[0335] Figure 1 The image forming apparatus 100 shown is a printer configured in series. The image forming apparatus 100 includes: a transport channel 4 for recording material R; four developing machines (1Y, 1M, 1C, 1K) corresponding to various colors: yellow (Y), magenta (M), cyan (C), and black (K); pairs of transfer media (2Y, 2M, 2C, 2K) and support rollers (3Y, 3M, 3C, 3K) corresponding to the developing machines of each color; an exposure device 5 that irradiates a laser based on the primary color image data obtainable by separating the primary image colors; and pairs of fixing rollers 6 and support rollers 7. The four developing machines (1Y, 1M, 1C, 1K) corresponding to each color are arranged in series along the transport direction D of the recording material R within the image forming apparatus. The four developing machines are arranged from the upstream side of the transport direction in the order of yellow developing machine 1Y, magenta developing machine 1M, cyan developing machine 1C, and black developing machine 1K.

[0336] The structure of the developing machine will be described using a yellow developing machine 1Y as an example. The developing machine 1Y has a drum-shaped photosensitive drum 11Y, around which are arranged: a charged roller 12Y that imparts a predetermined potential to the surface of the photosensitive drum; a laser irradiation section 13Y that irradiates the photosensitive drum 11Y with laser light generated in the exposure device to form an electrostatic image; a developing section 14Y that supplies charged toner to the electrostatic image to develop it; a roller-shaped transfer medium 2Y that transfers the developed toner image; and a cleaning section 15Y that removes toner residue from the photosensitive drum 11Y after the toner image has been transferred to the transfer medium. Furthermore, the developing section 14Y is connected to a toner storage section 16Y via a yellow toner supply channel.

[0337] Other color developing machines also have photosensitive drums (11M, 11C, 11K), charged rollers (12M, 12C, 12K), laser irradiation units (13M, 13C, 13K), developing units (14M, 14C, 14K), cleaning units (15M, 15C, 15K), and toner storage units (16M, 16C, 16K). Transfer media (2M, 2C, 2K) are arranged around the photosensitive drum along with these components.

[0338] The method for forming an image using the image forming apparatus 100 described above will be explained. In this apparatus, a yellow toner is selected as the first toner and used in the initial developing machine 1Y. Furthermore, various toners of magenta (M), cyan (C), and black (K) are used as second toners in subsequent developing machines.

[0339] First, in the yellow developing machine 1Y, the surface of the photosensitive drum 11Y is uniformly charged by the charged roller 12Y. The photosensitive drum is typically high resistivity (the resistance of ordinary resin), but it has the property that the resistivity of the portion irradiated by the laser beam changes when exposed to laser light. Therefore, in the exposure apparatus 5, a laser beam is generated based on the yellow primary color image data and irradiated onto the surface of the charged photosensitive drum 1Y via the laser irradiation unit 13Y. The laser beam irradiates the photosensitive layer on the surface of the photosensitive drum 11Y, thereby forming an electrostatic latent image corresponding to the yellow primary color image on the surface of the photosensitive drum 11Y.

[0340] An electrostatic latent image is formed by residual charge in the part that was not irradiated by the laser beam, and therefore it is a negative latent image.

[0341] The electrostatic latent image on the photosensitive drum 11Y is moved to the position of the developing section 14Y by the rotation of the photosensitive drum, where it is developed to obtain a yellow primary tone toner image.

[0342] The yellow primary toner image on the photosensitive drum is moved to the primary transfer position by the rotation of the photosensitive drum. At the primary transfer position, the surface of the photosensitive drum 11Y abuts against the surface of the transfer medium 2Y, where the yellow primary toner image on the photosensitive drum is transferred onto the surface of the transfer medium 2Y.

[0343] The yellow primary toner image on the transfer medium 2Y is moved to the secondary transfer position by the rotation of the transfer medium. At the secondary transfer position, the recording material R on the transport channel 4 is sandwiched between the transfer medium 2Y and the support roller 3Y, and the surface of the transfer medium 2Y abuts against the image receiving surface of the recording material R, thus transferring the yellow primary toner image of the transfer medium 2Y to the recording material R for the second time.

[0344] Next, in the magenta developing machine 1M, the same steps as those for forming the yellow primary toner image are performed. That is, in the magenta developing machine 1M, the magenta primary toner image is formed on the surface of the photosensitive drum 11M, transferred once to the surface of the transfer medium 2M, and moved to the secondary transfer position by rotating the transfer medium 2M. Meanwhile, the portion of the recording material R with the formed yellow primary toner image moves from the upstream side of the transport channel 4, bringing the magenta to the secondary transfer position. Here, the magenta primary toner image on the transfer medium 2M aligns with the yellow primary toner image on the recording material R, and is transferred a second time onto the recording material R.

[0345] Next, in the cyan developer 1C and the black developer 1K, the same steps as those for forming the yellow primary toner image are performed. Then, on the recording material R moving in the transport channel, the primary toner images of various colors—yellow (Y), magenta (M), cyan (C), and black (K)—are sequentially superimposed to obtain a multicolor image. After the recording material R has passed through all the color developers and formed the multicolor image, it moves to the fixing position. Here, the multicolor image is fixed onto the recording material by clamping the recording material R between the fixing roller 6 and the support roller 7.

[0346] Example

[0347] The present invention will be described in more detail below with examples and comparative examples, but the present invention is not limited to these examples. Furthermore, unless otherwise specified, parts and percentages are based on mass.

[0348] Furthermore, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the resin were calculated using GPC-based polystyrene conversion. The sample used for the assay was prepared as follows: the polymer was dissolved in tetrahydrofuran (THF) at a concentration of 2 mg / mL, sonicated for 10 minutes, and then passed through a 0.45 μm membrane filter. The assay conditions were: temperature: 40 °C; solvent: tetrahydrofuran; flow rate: 1.0 mL / min; concentration: 0.2 wt%; sample injection volume: 100 μL; and the chromatographic column used was a GPC TSKgel Multipore HXL-M (30 cm × 2 columns) manufactured by Tosoh Corporation.

[0349] [Manufacturing Example 1: Manufacturing of Magenta Pigment A]

[0350] 2,5-Di-(4-methylphenylamino)terephthalic acid was cyclized in phosphoric acid to synthesize 2,9-dimethylquinacridone (CI Pigment Red 122). Water was added to the resulting phosphoric acid dispersion of 2,9-dimethylquinacridone, and the mixture was filtered and further washed with water. Water was added again to the washed 2,9-dimethylquinacridone to prepare an aqueous dispersion with a solid content of 20%.

[0351] Similarly, using 2,5-di-phenylaminoterephthalic acid, an aqueous dispersion of quinacridone (CI Pigment Violet 19) with a solid content of 20% was prepared.

[0352] 250 parts of ethanol were added to 250 parts of an aqueous dispersion of 20% dimethyl quinacridone (CI Pigment Red 122) and 250 parts of an aqueous dispersion of 20% quinacridone (CI Pigment Violet 19) to prepare a pigment mixture. This mixture was transferred to a container equipped with a cooling tube, and the pigment was ground while reacting under reflux for 5 hours. After the reaction was complete, the pigment was filtered, washed, dried, and pulverized from the reaction solution to obtain magenta pigment A, a mixed crystal of CI Pigment Red 122 and CI Pigment Violet 19. The mass ratio of each pigment in this mixed crystal was CI Pigment Red 122 : CI Pigment Violet 19 = 1 : 1.

[0353] [Manufacturing Example 2: Manufacturing of Polyester Resin (1)]

[0354] 536 parts of 4-methyl-hexahydrophthalic anhydride, 100 parts of bis(β-hydroxyethyl) hexahydrophthalate, 30 parts of dimethyl 5-aminohexahydroisophthalate, 284 parts of hydrogenated bisphenol A, and 150 parts of ethylene glycol were added to a three-necked flask equipped with a stirrer, thermometer, reflux cooling pipe, water distribution pipe, and nitrogen inlet pipe. The ratio of the total hydroxyl value [X] to the total acid value [Y] was 1.07. Nitrogen gas was introduced while stirring to remove the alcohol generated in the reaction, and the reaction was carried out at 200°C for 3 hours. Then, 5 parts of tetrabutoxytitanium were added, the reaction temperature was increased to 220°C, and the pressure in the flask was gradually reduced until it dropped below 5 mmHg after 1.5 hours. The reaction was then continued for another 3 hours to obtain a polyester resin (1).

[0355] The obtained polyester resin (1) has a number average molecular weight of 3000, a weight average molecular weight of 14000, a hydroxyl value of 38 mgKOH / g, and a glass transition temperature of 65℃.

[0356] [Manufacturing Example 3: Manufacturing of Polyester Resin (2)]

[0357] 93 parts of 1,4-cyclohexanedicarboxylic acid, 7 parts of 1,3,5-cyclohexanetricarboxylic acid, 60 parts of hydrogenated bisphenol A, and 40 parts of 1,4-cyclohexanediol were added to a three-necked flask equipped with a stirrer, thermometer, reflux cooling pipe, water separator, and nitrogen inlet pipe. Nitrogen gas was introduced while stirring to remove water generated during the reaction, and the mixture was allowed to react at 200°C for 5 hours. Then, 0.5 parts of ferric acetylacetone were added to raise the reaction temperature to 220°C. The pressure inside the flask was gradually reduced until it dropped below 5 mmHg after 1.5 hours, and the reaction was continued for another 5 hours to obtain a polyester resin (2).

[0358] The obtained polyester resin (2) is a pale yellow transparent solid with a number average molecular weight of 8500, a weight average molecular weight of 28000, and a glass transition temperature of 62℃.

[0359] [Manufacturing Example 4: Manufacturing of Acrylic Resin P1 Containing Acidic Groups]

[0360] 200 parts of toluene were added to the reaction vessel, and nitrogen was completely displaced from the reaction vessel while stirring the toluene. The toluene was then heated to 90°C. Next, a mixed solution of 97.0 parts of methyl methacrylate, 2.6 parts of ethyl acrylate, 0.4 parts of acrylic acid, and 3 parts of tert-butyl peroxide (manufactured by Nippon Yushu Co., Ltd., trade name: Perbutyl O) was added dropwise to the reaction vessel over a period of 2 hours. The polymerization was then completed by reflux of toluene for 10 hours. The solvent was then removed by distillation under reduced pressure. This yielded an acid-containing acrylic resin P1 (MMA / EA / AA). The acid-containing acrylic resin P1 had an acid value of 2.5 mg KOH / g, a Tg of 74°C, and a Mw of 12600.

[0361] [Example 1]

[0362] 1. Manufacturing of colored resin particles

[0363] (1) Preparation of nuclear polymeric monomer compositions:

[0364] The following were wet-milled using a media disperser (manufactured by Asada Iron Works Co., Ltd., trade name: PICOMILL): 74 parts of styrene as a binder resin, 26 parts of n-butyl acrylate, 0.1 parts of polymethyl methacrylate macromonomer (manufactured by Toa Synthetic Chemical Industry Co., Ltd., trade name: AA-6, Tg=94°C), 5 parts of the polyester resin (1) obtained in the above manufacturing example 2, 0.50 parts of tetraethyl thiuram disulfide as a molecular weight regulator, and yellow pigments (6.5 parts of CI Pigment Yellow 214 and 1.5 parts of CI Solvent Yellow 98) as colorants.

[0365] To the mixture obtained by the above wet pulverization, add 12.0 parts of synthetic ester wax 1 (hexaglycerol octabenzene ester, melting point 70°C) as a release agent and 0.1 parts of nonionic surfactant A (polyoxyethylene (stilbene phenyl) ether, trade name: Emulgen A-60, manufactured by Kao Corporation, average addition molar number of polyoxyethylene: 13) as a release agent and mix. Then, 5.0 parts of a styrene-acrylic resin containing quaternary ammonium salt (functional group content 0.5% by mass), 2.0 parts of a styrene-based thermoplastic elastomer (styrene-isoprene-styrene block copolymer, styrene unit content: 24% by mass, weight average molecular weight Mw: 106000, manufactured by Zeon Corporation, Japan, trade name: Quintac 3270), and 1.0 part of the acidic acrylic resin P1 obtained in Manufacturing Example 4 above were added to the mixture and mixed and dissolved to prepare a core polymerizable monomer composition.

[0366] (2) Preparation of aqueous dispersion media:

[0367] On the other hand, a magnesium hydroxide colloidal dispersion was prepared by slowly adding an aqueous solution of sodium hydroxide dissolved in 50 parts of ion-exchanged water to an aqueous solution of magnesium chloride dissolved in 280 parts of ion-exchanged water with stirring.

[0368] (3) Preparation of shell polymerizable monomers:

[0369] On the other hand, an aqueous dispersion of shell polymerizable monomers was prepared by micro-dispersing 2 parts of methyl methacrylate and 130 parts of water using an ultrasonic emulsifier.

[0370] (4) Granulation process:

[0371] The above-mentioned core polymerizable monomer composition was added to the above-mentioned magnesium hydroxide colloidal dispersion (5.3 parts magnesium hydroxide), and then stirred. Six parts of tert-butyl peroxide-2-ethylbutyrate, as a polymerization initiator, were added. The dispersion containing the polymerization initiator was dispersed using an inline emulsifying disperser (manufactured by Taihei Kiko Co., Ltd., trade name: Milder) at a speed of 15,000 rpm to form droplets of the core polymerizable monomer composition.

[0372] (5) Suspension polymerization process:

[0373] A dispersion of droplets containing the core-shell polymerizable monomer composition was added to a reactor, and the temperature was raised to 90°C for polymerization. After the polymerization conversion reached approximately 100%, a solution of 0.1 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-086, water-soluble initiator) was dissolved in the aqueous dispersion of the shell-shell polymerizable monomer as a shell polymerization initiator was added to the reactor. The polymerization was then continued at 95°C for 4 hours, followed by water cooling to terminate the reaction, yielding a dispersion of core-shell colored resin particles.

[0374] (6) Post-processing steps:

[0375] While stirring the aqueous dispersion of the coloring resin particles, sulfuric acid was added for acid washing until the pH reached below 4.5 (30°C, 10 minutes). The filtered coloring resin particles were then washed with water, and the washing water was filtered out. At this point, the conductivity of the filtrate was 10 μS / cm. Next, the coloring resin particles were dehydrated and dried to obtain dried coloring resin particles.

[0376] 2. Manufacturing of toners

[0377] To 100 parts of coloring resin particles, 0.2 parts of silica microparticles with an average particle size of 7 nm after dehydration treatment, 0.76 parts of silica microparticles with an average particle size of 20 nm after dehydration treatment, and 1.91 parts of silica microparticles with an average particle size of 50 nm after dehydration treatment were added, and the mixture was prepared using a high-speed mixer (manufactured by Nippon Kogyo Co., Ltd., trade name: FMMixer) to prepare the toner of Example 1.

[0378] [Examples 2-3]

[0379] In Example 1, in the above "(1) Preparation of the polymeric monomer composition for the core" of "1. Manufacturing of colored resin particles", the type of colorant was changed according to Table 1 below. Otherwise, the colorants of Examples 2 and 3 were obtained in the same manner as in Example 1.

[0380] In addition, the cyan pigment used in Example 2 is CI Pigment Blue 15:3. The magenta pigment A used in Example 3 is the magenta pigment A obtained in Manufacturing Example 1 above.

[0381] [Examples 4-7 and Comparative Examples 2, 3, 5, 6]

[0382] In Example 1, in the above "(1) Preparation of the polymerizable monomer composition for the core" of "1. Manufacturing of colored resin particles", the type, amount or both of the release agent and dispersant were changed according to Table 1 or Table 2 below. Otherwise, the colorants of Examples 4 to 7 and the colorants of Comparative Examples 2, 3, 5 and 6 were obtained in the same manner as in Example 1.

[0383] In addition, the nonionic surfactant B used in Example 4 was polyoxyethylene lauryl ether (trade name: Emulgen 120, manufactured by Kao Corporation). The nonionic surfactant C used in Example 5 was polyoxyethylene lauryl ether (trade name: Emulgen 109P, manufactured by Kao Corporation). The anionic surfactant A used in Comparative Example 5 was Neogen (registered trademark) (trade name, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., sodium linear alkylbenzene sulfonate or sodium α-olefin sulfonate). The cationic surfactant A used in Comparative Example 6 was alkylbenzyl dimethyl ammonium chloride (trade name: SANISOL (registered trademark) B50, manufactured by Kao Corporation). No release agent or dispersant was added in Comparative Example 2.

[0384] [Examples 8, 9 and Comparative Example 1]

[0385] In Example 1, in the above "(1) Preparation of the polymeric monomer composition for the core" of "1. Manufacturing of colored resin particles", the type or amount of polyester resin was changed according to Table 1 or Table 2 below. Otherwise, the toners of Examples 8 and 9 and the toner of Comparative Example 1 were obtained in the same way as in Example 1.

[0386] In addition, the polyester resin (2) used in Example 9 is the polyester resin (2) obtained in Manufacturing Example 3 above. No polyester resin was added in Comparative Example 1.

[0387] [Comparative Example 4]

[0388] In Example 1, in the above "(1) Preparation of the polymeric monomer composition for the core" of "1. Manufacturing of colored resin particles", the type of release agent was changed according to Table 2 below. Otherwise, the colorant of Comparative Example 4 was obtained in the same way as in Example 1.

[0389] In addition, the hydrocarbon wax used in Comparative Example 4 is a natural gas-based Fischer-Tropsch wax (trade name: FT-100, manufactured by Shell MDS) with an endothermic peak temperature of 93°C, a weight-average molecular weight of 1000, and a number-average molecular weight of 670.

[0390] [Example 10]

[0391] In Example 1, in the above "(1) Preparation of the nuclear polymeric monomer composition" of "1. Manufacturing of colored resin particles", the type of colorant was changed according to Table 3 below, and styrene-based thermoplastic elastomer was not added. Otherwise, the colorant of Example 10 was obtained in the same way as in Example 1.

[0392] In addition, the magenta pigment A used in Example 10 is the magenta pigment A obtained in Manufacturing Example 1 above.

[0393] [Example 11]

[0394] In Example 1, in the above "(1) Preparation of the nuclear polymeric monomer composition" of "1. Manufacturing of colored resin particles", the amount of nonionic surfactant A added was changed according to Table 3 below. Otherwise, the colorant of Example 11 was obtained in the same way as in Example 1.

[0395] [Example 12]

[0396] In Example 1, in the above "(1) Preparation of the polymerizable monomer composition for the core" of "1. Manufacturing of colored resin particles", 5.0 parts of styrene acrylic resin containing quaternary ammonium salt (functional group content 15% by mass, trade name: FCA-201-PS, manufactured by Fujikura Chemical Co., Ltd.) were used instead of 5.0 parts of styrene acrylic resin containing quaternary ammonium salt (functional group content 0.5% by mass) as the charge control resin. Otherwise, the colorant of Example 12 was obtained in the same manner as in Example 1.

[0397] [Examples 13-14]

[0398] In Example 1, in the above "(1) Preparation of the polymeric monomer composition for the core" of "1. Manufacturing of colored resin particles", the type of release agent was changed according to Table 3 below. Otherwise, the colorants of Examples 13 and 14 were obtained in the same manner as in Example 1.

[0399] In addition, the ester wax 2 mentioned in Table 3 below is pentaerythritol tetrabenzyl ester (melting point 76°C), and the ester wax 3 is stearate behenate (melting point 67°C).

[0400] [Example 15]

[0401] In Example 1, in the above "(1) Preparation of the polymerizable monomer composition for the core" of "1. Manufacturing of colored resin particles", 5 parts of CI pigment blue 15:3 were used instead of yellow pigment (6.5 parts of CI pigment yellow 214 and 1.5 parts of CI solvent yellow 98). Otherwise, the colorant of Example 15 was obtained in the same manner as in Example 1.

[0402] [Example 16]

[0403] In Example 1, in the above "(1) Preparation of the polymerizable monomer composition for the core" of "1. Manufacturing of colored resin particles", 8 parts of CI pigment red 122 were used instead of yellow pigment (6.5 parts of CI pigment yellow 214 and 1.5 parts of CI solvent yellow 98). Otherwise, the colorant of Example 16 was obtained in the same manner as in Example 1.

[0404] [Examples 17-18]

[0405] In Example 1, in the above "(1) Preparation of the polymeric monomer composition for the core" of "1. Manufacturing of colored resin particles", the toners of Examples 17 and 18 were obtained in the same manner as in Example 1, except that the amount of added ester wax 1 and nonionic surfactant A were added according to Table 3 below.

[0406] [Examples 19-20]

[0407] In Example 1, during the "(1) Preparation of the polymerizable monomer composition for the core" section of "1. Manufacturing of colored resin particles", the type and amount of release agent were changed according to Table 3 below. Otherwise, the colorants of Examples 19 and 20 were obtained in the same manner as in Example 1. In addition, the hydrocarbon waxes listed in Table 3 are the same as those used in Comparative Example 4.

[0408] [Examples 21-23]

[0409] In Example 1, during the "(1) Preparation of the polymerizable monomer composition for the core" section of "1. Manufacturing of colored resin particles" above, the type and amount of release agent and dispersant were changed according to Table 3 below. Otherwise, the colorants of Examples 21 to 23 were obtained in the same manner as in Example 1. In addition, the nonionic surfactant D listed in Table 3 is polyoxyalkylene ether (trade name: LATEMUL PD-420, manufactured by Kao Corporation), the anionic surfactant B is sodium polyoxyethylene lauryl ether sulfate (manufactured by Kao Corporation), and the anionic surfactant C is dodecylbenzene sulfonic acid.

[0410] [Determination and Evaluation of Toners]

[0411] (1) Average roundness

[0412] 10 ml of deionized water was added to a container beforehand, followed by 0.2 g of an aqueous surfactant solution (manufactured by Fujifilm Corporation, trade name: DRIWEL) as a dispersant, and then 0.2 g of toner. The mixture was then dispersed using an ultrasonic disperser at 60 W for 3 minutes. The toner particle concentration was adjusted to 3000–10000 particles / μL for measurement. 1000–10000 toner particles with an equivalent spherical diameter of 0.4 μm or larger were measured using a flow particle image analyzer (manufactured by Sysmex Corporation, trade name: FPIA-2100). The average sphericity was calculated based on the measured values.

[0413] The roundness is shown in the following formula, and the average roundness is its average value.

[0414] (Circularity) = (Circumference of a circle with the same projected area as the particle) / (Circumference of the particle's projected image)

[0415] (2) Volume average particle size (Dv), number average particle size (Dp), and particle size distribution (Dv / Dp)

[0416] Weigh approximately 0.1 g of the toner into a beaker, and add 0.1 mL of an aqueous surfactant solution (manufactured by Fujifilm, trade name: DRIWEL) as a dispersant. Further add 10–30 mL of ISOTON II to the beaker, and disperse using a 20 W ultrasonic disperser for 3 minutes. Then, using a particle size distribution measuring device (manufactured by Beckman Coulter, trade name: MULTISIZER), measure the volume average particle size (Dv) and number average particle size (Dp) of the toner particles under the following conditions: pore size: 100 μm; medium: ISOTON II; number of particles: 100,000. Calculate the particle size distribution (Dv / Dp).

[0417] (3) Heat resistance temperature

[0418] Add 10g of toner to a 100mL polyethylene container and seal it. Submerge the container in a constant-temperature water bath with a temperature set to a predetermined level, starting at 50°C and decreasing by 1°C each time. After 8 hours, remove the container. Transfer the toner from the container onto a 42-mesh sieve with minimal vibration and place it on a powder testing machine (manufactured by Hosokawa Micron Co., Ltd., trade name: Powder Tester (registered trademark) PT-R). Set the sieve amplitude to 1.0mm and vibrate for 30 seconds. Measure the mass of toner remaining on the sieve and take this as the mass of agglomerated toner.

[0419] The highest temperature at which the mass of the condensed toner is less than 0.5g is taken as the heat resistance temperature of the toner.

[0420] The higher the heat resistance temperature, the less likely the toner is to clump together during storage, and the better its shelf life. In the following evaluation criteria, the shelf life is evaluated in the order of C, B, and A, with D being unacceptable.

[0421] (Evaluation criteria for heat resistance temperature)

[0422] A: Above 59℃

[0423] B: Temperature above 56℃ and below 59℃

[0424] C: 53℃ or higher but less than 56℃

[0425] D: Less than 53℃

[0426] (4) Fixing temperature

[0427] A commercially available non-magnetic single-component developer printer was modified to allow for temperature adjustment of the fuser roller. Using this printer, the fuser roller temperature was varied by 5°C increments starting from 120°C. The fixing rate of the toner was measured at each temperature, and the temperature-fixing rate relationship was determined. The lowest temperature at which a fixing rate of over 80% was obtained was defined as the fixing temperature of the toner. The lower the fixing temperature, the better the low-temperature fixing properties of the toner.

[0428] Additionally, the fixing rate is calculated based on the image density ratio of the solid area in the test paper printed in the printer before and after the rubbing test. When the image density before the rubbing test is set as ID(before) and the image density after the rubbing test is set as ID(after), the fixing rate (%) = [ID(after) / ID(before)] × 100. The rubbing test is conducted as follows: the test portion of the test paper is attached to the firmness tester with adhesive tape, a load of 500g is applied, and the paper is rubbed back and forth 5 times using a rubbing terminal made of rolled cotton cloth. In the following evaluation criteria, the ability to evaluate low-temperature fixing performance is best in the order of C, B, and A, with D being unacceptable.

[0429] (Evaluation criteria for fixing temperature)

[0430] A: Less than 155℃

[0431] B: Temperature above 155℃ and below 170℃

[0432] C: Temperature above 170℃ and below 185℃

[0433] D: Above 185℃

[0434] (5) Initial fog test

[0435] The printing paper was installed in a commercially available non-magnetic single-component developing printer (printing speed: 30 sheets / minute). The toner was added to the developing unit and placed in a high temperature and high humidity (H / H) environment of 35°C and 80% RH for 24 hours. Then, three sheets were printed continuously in the same environment at a printing density of 5%.

[0436] Next, full-white printing (0% printing density) is performed. During the full-white printing process, the printer is stopped, and the toner on the non-image portion of the developed photosensitive drum is applied to the adhesive tape (manufactured by Sumitomo 3M Co., Ltd., product name: Scotch Mending tape 810-3-18), which is then attached to the printing paper. Next, the whiteness (B) of the printing paper with the adhesive tape is measured using a whiteness meter (manufactured by Nippon Denshoku Co., Ltd.). Similarly, the whiteness (A) of the unused adhesive tape is measured on the printing paper, and the difference (BA) between these whitenesses is taken as the haze value. The smaller the haze value, the less haze and the better the quality. In the following evaluation criteria, C, B, and A are considered the least likely to produce haze and the best quality, respectively; D is considered unacceptable.

[0437] (Evaluation criteria for initial fog)

[0438] A: Fog value is 0 or higher and less than 2

[0439] B: Fog value is 2 or higher and less than 4

[0440] C: Fog value is 4 or higher and less than 8

[0441] D: Fog value is 8 or above

[0442] (6) Uneven gloss

[0443] Toner was added to a commercially available non-magnetic, single-component developing printer. A solid 5cm x 5cm square was printed on printing paper at 23°C and 50% humidity. The developing bias voltage was then changed to alter the amount of toner on the printing paper, i.e., the developing amount M / A. The unfixed image was removed from the printer, and the toner developed on the printing paper was blown away with air. The developing amount M / A was then calculated using the following formula.

[0444] M / A (mg / cm 3 )=(W1-W2) / 25cm 2

[0445] W1 = Weight of the printing paper before the toner is blown away (mg)

[0446] W2 = Weight of the printing paper after the toner has been blown away (mg)

[0447] The measured M / A ratio was 0.35 mg / cm³. 2The gloss of a solid 5cm x 5cm square printed image was measured. Specifically, the gloss values ​​at five locations—the four corners and the center—of the solid 5cm quadrilateral area were measured using a gloss meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., trade name: VGS-SENSOR) at an incident angle of 60°. The maximum and minimum gloss values ​​at the five locations were determined, and then the average gloss value at the five locations was calculated. The gloss unevenness was then calculated using the following formula.

[0448] Uneven gloss (%) = {(maximum value - minimum value) / average value} × 100

[0449] In the following evaluation criteria, the uneven gloss can be evaluated as less and better in the order of C, B, and A, while D is unacceptable.

[0450] (Evaluation criteria for uneven gloss)

[0451] A: Uneven gloss level less than 20%

[0452] B: The gloss level is not uniformly above 20% but below 25%.

[0453] C: Gloss level is not uniformly above 25% but below 30%.

[0454] D: Gloss level is not uniform (above 30%)

[0455] (7) Amount of surfactant on the surface of toner particles

[0456] (7-1) Extraction of nonionic surfactants

[0457] In Examples 1-23 and Comparative Examples 1-4, 10 g of toner was dispersed in 100 mL of a mixed solvent of IPA and ion-exchanged water (IPA / ion-exchanged water = 80 / 20 (volume ratio)), stirred at 50°C for 30 minutes, and the liquid components were separated to prepare an extract of the toner.

[0458] Next, the extract of the toner was treated with a weakly basic anion exchange resin (DIAIONWK10, manufactured by Mitsubishi Chemical) and a weakly acidic cation exchange resin (DIAIONWK20, manufactured by Mitsubishi Chemical). The toner extract treated in this way was used for the determination of the amount of surfactant described later.

[0459] Furthermore, the treatment using the aforementioned ion exchange resin is for removing ionic surfactants. In Examples 1-9, Comparative Examples 1-4, Examples 10-20, and Example 23, since no ionic surfactants were used, the presence or absence of the aforementioned ion exchange resin treatment did not affect the determination results of the surfactant quantity. On the other hand, in Examples 21-22, by utilizing the aforementioned ion exchange resin treatment, anionic surfactants were removed, and only the quantity of nonionic surfactants could be determined.

[0460] (7-2) Extraction of ionic surfactants

[0461] In Comparative Examples 5-6 and Examples 21-22, the extract of the toner was prepared in the same manner as the extraction of the nonionic surfactant described above, and the prepared extract of the toner was directly used for the determination of the amount of surfactant described later without treatment using an ion exchange resin. In Comparative Examples 5-6, since only an ionic surfactant was used as a release agent dispersant, the amount of ionic surfactant could be determined. In Examples 21-22, since the extract of the toner contained both nonionic and ionic surfactants, the peaks attributed to the ionic surfactant were determined based on the peaks of individual materials, thereby determining the amount of ionic surfactant alone.

[0462] (7-3) Determination of surfactant content

[0463] The amount of surfactant in the extract of the colorant was determined by liquid chromatography-mass analysis (LC / MS). The specific determination method is as follows.

[0464] First, the individual materials contained in the toner were analyzed using LC / MS to determine the peaks (molecular weight) belonging to each material. Next, the extract of the toner was analyzed using LC / MS. Based on the pre-determined results of each individual material, the peaks of materials other than surfactants were removed from the peaks detected in the extract of the toner, thereby determining the amount of surfactant.

[0465] The LC / MS determination conditions are shown below.

[0466] (LC / MS determination conditions)

[0467] • Liquid chromatography-mass spectrometry analysis equipment: UPLC H-Class, Xevo G2-XS QTof (manufactured by Waters Corporation)

[0468] ·LC conditions

[0469] Device: UPLCH-Class

[0470] Column: ACQUITY UPLC C8 1.7μm, 2.1×100mm

[0471] Column temperature: 40℃

[0472] Mobile phase: A: 0.1% formic acid, B: MeOH containing 0.1% formic acid

[0473] Flow rate: 0.5 mL / min

[0474] Injection volume: 2μL

[0475] ·MS conditions

[0476] Device: Xevo G2-XS Q-Tof

[0477] Ionization mode: ESI positive ion / negative ion

[0478] Capillary voltage: 1.0kV / 2.5kV

[0479] Desolvation gas: 1000L / hr, 500℃

[0480] Conical orifice gas: 50L / hr

[0481] Tapered hole voltage: 40V (offset 80V)

[0482] Collision energy: 2eV

[0483] Measurement range: m / z 100-1000

[0484] Measurement mode: MS Sensitivity Mode (resolution / 30000)

[0485] MS / MS conditions

[0486] Collision energy

[0487] Low energy: 6eV

[0488] High energy: 30eV to 50eV (ramp start to end)

[0489] In addition, the amount of long-chain fatty acid-polyether nonionic surfactant with 12 to 22 carbon atoms can be approximately determined based on the intensity of the m / z = 160-320 peak from long-chain fatty acids with 12 to 22 carbon atoms.

[0490] (8) Conductivity of the extract of the toner

[0491] 10 g of the toner was dispersed in 100 mL of a mixed solvent of IPA and deionized water (IPA / deionized water = 80 / 20 (volume ratio)). After stirring at 50 °C for 30 minutes, the liquid components were separated to prepare the toner extract. The conductivity of the toner extract was measured at 25 ± 0.5 °C using a conductivity meter (manufactured by Horiba Manufacturing Co., Ltd., trade name "ES-12"). Deionized water with a conductivity of 0.8 μS / cm or less was used as the deionized water.

[0492] [Table 1]

[0493]

[0494] [Table 2]

[0495]

[0496] [Table 3]

[0497]

[0498] [Inspection]

[0499] The toner in Comparative Example 1 has poor low-temperature fixing properties because it does not contain polyester resin as a binder.

[0500] The toner in Comparative Example 2 does not contain release agent or dispersant, resulting in poor low-temperature fixing properties.

[0501] The toner in Comparative Example 3 contains a large amount of nonionic surfactant that acts as a release agent and dispersant, resulting in a nonionic surfactant mass greater than 500 ppm on the surface of the toner particles. Therefore, it has poor heat resistance and is prone to producing haze.

[0502] Because the toner in Comparative Example 4 does not contain ester waxes but rather hydrocarbon waxes as a release agent, the mass of nonionic surfactant present on the surface of the toner particles is greater than 500 ppm, which easily leads to haze and uneven gloss. It is believed that the rapid crystallization rate of hydrocarbon waxes after toner fixing and during rapid cooling easily causes uneven gloss. Furthermore, it is believed that hydrocarbon waxes are difficult to dissolve surfactants, causing surfactant separation and concentration on the surface, thus resulting in a high amount of nonionic surfactant present on the surface of the toner particles in Comparative Example 4.

[0503] Because the toners in Comparative Examples 5 and 6 used ionic surfactants instead of nonionic surfactants as release agent dispersants, they were prone to producing haze. This is believed to be because ionic surfactants, compared to nonionic surfactants, more easily affect the charge of the toner, thus making the charge of the toner unstable.

[0504] On the other hand, the toners of Examples 1-9 are positively charged toners of the present invention, containing styrene-acrylic resin and polyester resin as binder resins, ester wax as release agent, and nonionic surfactant as release agent dispersant. The mass of the aforementioned nonionic surfactant present on the surface of the toner particles is 30-500 ppm relative to the mass of the toner particles. Therefore, the toners of Examples 1-9 exhibit excellent low-temperature fixing and heat preservation properties, are less prone to haze, and can form images with less gloss unevenness.

[0505] Among them, the comparison of Examples 1 to 5 shows that when nonionic surfactant A (polyoxyalkylene styrene aryl ether surfactant) is used as the release agent dispersant, the resulting toner tends to have excellent low-temperature fixing properties and heat-resistant preservation properties.

[0506] Furthermore, a comparison of Examples 1-6, 8-9 and Example 7 shows that when the mass of the nonionic surfactant present on the surface of the toner particles is less than 400 ppm, the generation of haze can be easily suppressed.

[0507] Furthermore, a comparison of Examples 1 and 9 shows that when a polyester resin (1) with a number-average molecular weight of 8,000 or less and a weight-average molecular weight of 20,000 or less is used as the polyester resin, the resulting toner exhibits superior low-temperature fixing properties and is less prone to producing haze compared to a polyester resin (2) with a number-average molecular weight greater than 8,000 and a weight-average molecular weight greater than 20,000.

[0508] The toners of Examples 10-23 are positively charged toners of the present invention, containing styrene-acrylic resin and polyester resin as binders, ester wax as a release agent, and nonionic surfactant as a release agent dispersant. The mass of the aforementioned nonionic surfactant present on the surface of the toner particles is 0.1-500 ppm relative to the mass of the toner particles. Therefore, the toners of Examples 10-23 exhibit excellent low-temperature fixing and heat preservation properties, are less prone to haze, and can form images with minimal gloss unevenness.

[0509] Furthermore, as shown in Examples 10, 11, and 12, the toner of the present invention, even without containing styrene-based thermoplastic elastomers, with a nonionic surfactant mass of less than 30 ppm, or with a large amount of functional groups in the charged control resin, can still achieve an excellent balance between low-temperature fixing and heat preservation, is less prone to haze, and can form images with excellent gloss uniformity. Moreover, a comparison between Examples 10 and 1 shows that when the toner of the present invention contains styrene-based thermoplastic elastomers, low-temperature fixing performance is improved and gloss unevenness is suppressed.

[0510] As shown in Examples 13 and 14, the above-mentioned effects can be obtained even when using polyfunctional ester waxes or monoester compounds other than glyceryl ester compounds as release agents. On the other hand, a comparison of Examples 13, 14 and Example 1 shows that when using glyceryl ester compounds as release agents, the balance between toner preservation and low-temperature fixing is optimal.

[0511] A comparison of Examples 15 and 2 shows that the above-mentioned effects can be obtained even when the coloring dosage is changed.

[0512] A comparison of Examples 16 and 3 shows that the above-mentioned effects can be obtained even when the toner of the present invention uses CI Pigment Red 122 alone as a toner.

[0513] As shown in Examples 17 and 18, the toner of the present invention, by adjusting the amount of release agent dispersant added according to the release agent content, can improve the dispersibility of the release agent and achieve a good balance between the toner's shelf life and low-temperature fixing properties. On the other hand, the results of Example 17 show that there is a tendency for the fixing temperature to increase when the release agent content decreases, and the results of Example 18 show that adhesion and fogging are more likely to occur when the release agent content increases.

[0514] As shown in Examples 19 and 20, the above-mentioned effects can be obtained even if the release agent of the colorant of the present invention contains two or more ester waxes, or a combination of ester waxes and hydrocarbon waxes.

[0515] As shown in Examples 21 and 22, the above-mentioned effects can be obtained even if the release agent and dispersant combination of the toner of the present invention contains both nonionic and ionic surfactants.

[0516] As shown in Example 23, the above-mentioned effects can be obtained even if the release agent dispersant of the colorant of the present invention contains two or more nonionic surfactants.

[0517] [Toner Set]

[0518] According to Table 4, the initial colorant that is transferred first, the other colorant 1 that is transferred second, and the other colorant 2 that is transferred third are combined as colorant groups 1 to 10.

[0519] The following evaluations were conducted on each toner group.

[0520] [Evaluation of uneven gloss]

[0521] A commercially available non-magnetic single-component developing printer (printing speed: 20 sheets / minute) is equipped with printing paper and a developing unit with multiple toner developing machines. According to Table 4, a starting toner, other toner 1, or other toner 2 are added to each toner developing machine. Overlap printing is performed at 23°C and 50% humidity, with a 5cm x 5cm square of solid tertiary color printing (100% print density) at a position 0.5cm from the front end in the paper feed direction. At this time, the primary color image formed by the starting toner, the primary color image formed by other toner 1, and the primary color image formed by other toner 2 are transferred onto the printing paper in the following order to form a tertiary color image. Furthermore, the developing bias voltage is changed, thereby changing the amount of toner on the printing paper, i.e., the developing amount M / A. The unfixed image is removed from the printer, and the toner developed on the printing paper is blown away with air. The developing amount M / A is calculated according to the following formula.

[0522] M / A (mg / cm 2 )=(W1-W2) / 25cm 2

[0523] W1 = Weight of the printing paper (mg) before the toner is blown away

[0524] W2 = Weight of the printing paper (mg) after the toner has been blown away.

[0525] The image is processed by a fixing roller at 160°C with an M / A ratio of 0.70 mg / cm². 2 The unfixed image of the three colors was fixed onto printing paper to obtain a 5cm × 5cm square solid three-color printed image. The gloss levels at five points (the four corners and the center) of the solid area of ​​the 5cm quadrilateral were measured using a gloss meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., trade name: VGS-SENSOR) at an incident angle of 60°. The maximum and minimum gloss levels at the five points were determined, and then the average gloss level was calculated. The gloss unevenness was then calculated using the following formula.

[0526] Uneven gloss (%) = {(maximum value - minimum value) / average value} × 100

[0527] In the following evaluation criteria, the uneven gloss can be evaluated as less and better in the order of C, B, and A, while D is unacceptable.

[0528] (Evaluation criteria for uneven gloss)

[0529] A: Uneven gloss level less than 20%

[0530] B: The gloss level is not uniformly above 20% but below 25%.

[0531] C: Gloss level is not uniformly above 25% but below 30%.

[0532] D: Gloss level is not uniform (above 30%)

[0533] [Stripping Evaluation]

[0534] A commercially available non-magnetic single-component developing printer (printing speed: 20 sheets / minute) was modified to allow for temperature adjustment of the fixing roller. Printing paper and a developing unit equipped with multiple toner developing machines were installed in this printer. According to Table 4, a starting toner, other toner 1, or other toner 2 were added to each toner developing machine. Overlap printing was performed at 23°C and 50% humidity, with a 5cm × 20cm rectangular solid tertiary color print (100% print density) at a position 0.5cm from the front end in the paper feed direction. At this time, the primary color image formed by the starting toner, the primary color image formed by other toner 1, and the primary color image formed by other toner 2 were transferred onto the printing paper in the following order to form a tertiary color image. Furthermore, the temperature of the fixing roller was varied by 5°C from 200°C to 150°C each time, resulting in a solid tertiary color print at each fixing temperature. In the resulting solid three-color printing, visually confirm whether peeling occurs at the interface between the toner layer and the paper, between toner layers, or within the toner layer. The temperature of the fixing roller during printing (fixing temperature) in the case of peeling is taken as the peeling temperature.

[0535] The evaluation method consists of four stages: A, B, C, and D. The lower the temperature at which peeling occurs, the better the multilayer fixing of the toner layer can be evaluated, and the more peeling is suppressed. Therefore, the evaluation of multilayer fixing is in the order of C, B, and A, with D being unacceptable.

[0536] (Evaluation criteria for divestiture)

[0537] A: The peeling occurs at a temperature below 160℃.

[0538] B: The peeling temperature is greater than 160°C but less than 165°C.

[0539] C: The peeling temperature is greater than 165°C and less than 170°C.

[0540] D: Peeling occurs at a temperature greater than 170℃

[0541] [Table 4]

[0542]

[0543] [Inspection]

[0544] Since the various color toners constituting the toner groups 1 to 6 are all toners of the present invention, the multicolor images (solid printing of three colors) formed using toner groups 1 to 6 have less uneven gloss. In addition, the peeling temperature is low, that is, the peeling of the toner layer is suppressed.

[0545] On the other hand, since toner group 7 contains toner (Y-8) of Comparative Example 1, which does not contain polyester resin as a binder, the multicolor images formed using toner group 7 exhibit greater gloss unevenness compared to those formed using toner groups 1 to 6. This is presumably because the toner (Y-8) of Comparative Example 1 is not easily melted, resulting in unevenness at the interface of the toner layer formed through this toner (Y-8). Furthermore, multicolor images formed using toner group 7 are prone to toner layer peeling. This is presumably because the toner (Y-8) is not easily melted, resulting in insufficient adhesion at the interface of the toner layer formed through this toner (Y-8).

[0546] Since toner group 8 contains toner (Y-9) from Comparative Example 2, which does not use release agent or dispersant, the multicolor images formed using toner group 8 exhibit greater gloss unevenness compared to those formed using toner groups 1-6. This is presumably because the ester wax in toner (Y-9) of Comparative Example 2 is unevenly dispersed, making it difficult for the toner (Y-9) to melt, resulting in unevenness at the interface of the toner layer formed by this toner (Y-9). Furthermore, multicolor images formed using toner group 8 are prone to toner layer peeling. This is presumably because toner (Y-9) is difficult to melt, resulting in insufficient adhesion of the toner layer formed by this toner (Y-9).

[0547] Because toner group 9 contains toner (Y-10) of Comparative Example 3 with a mass greater than 500 ppm of nonionic surfactant present on the surface of toner particles, multicolor images formed using toner group 9 are prone to toner layer peeling. This is presumably because the amount of nonionic surfactant added to toner (Y-10) of Comparative Example 3 is excessive, resulting in overly fine dispersion of the release agent. During toner fixing, the release agent easily seeps out from the surface of the toner particles, leading to interfacial peeling between the toner particles forming the toner layer.

[0548] Because toner group 10 contains toner (Y-11) of Comparative Example 4, which contains only hydrocarbon wax as a release agent, the gloss of the multicolor image formed using toner group 10 is uneven. This is believed to be because the hydrocarbon wax contained in toner (Y-11) of Comparative Example 4 crystallizes quickly. Furthermore, compared to the cases using toner groups 1-6, the multicolor image formed using toner group 10 is more prone to toner layer peeling. This is believed to be because in toner (Y-11) of Comparative Example 4, the compatibility between the binder resin and the release agent is too high, causing the release agent to seep out onto the surface of the toner particles during toner fixing, resulting in interfacial peeling between the toner particles.

Claims

1. A positively charged toner for electrostatic image development, comprising coloring resin particles, said coloring resin particles comprising a binder resin, a colorant, a release agent, a release agent dispersant, and a charge control agent. The adhesive resin contains styrene-acrylic resin and polyester resin. The release agent contains ester wax. The release agent contains a nonionic surfactant as a dispersant, and the mass of the nonionic surfactant present on the surface of the toner particles is 30 to 500 ppm relative to the mass of the toner particles.

2. A positively charged toner for electrostatic image development, comprising coloring resin particles, said coloring resin particles comprising a binder resin, a colorant, a release agent, a release agent dispersant, and a charge control agent. The adhesive resin contains styrene-acrylic resin and polyester resin. The release agent contains ester wax. The release agent contains a nonionic surfactant as a dispersant, and the mass of the nonionic surfactant present on the surface of the toner particles is more than 0.1 ppm and less than 30 ppm relative to the mass of the toner particles.

3. The positively charged toner for electrostatic image development according to claim 1 or 2, wherein, It contains a charge control resin as the charge control agent.

4. The positively charged toner for electrostatic image development according to claim 1 or 2, wherein, The mass ratio of the styrene-acrylic resin to the polyester resin (styrene-acrylic resin: polyester resin) is 96:4 to 70:

30.

5. The positively charged toner for electrostatic image development according to claim 1 or 2, wherein, The colored resin particles also contain styrene-based thermoplastic elastomers.

6. The positively charged toner for electrostatic image development according to claim 1 or 2, wherein, The average roundness of the toner particles is above 0.96, and the ratio of the volume average particle size (Dv) to the number average particle size (Dp), i.e., the particle size distribution (Dv / Dp), is less than 1.

3.

7. The positively charged toner for electrostatic image development according to claim 1 or 2, wherein, The ester wax is a polyfunctional ester compound containing fatty acids with 10 to 22 carbon atoms and a polyol.

8. A toner set, comprising a color toner set containing positively charged toners for electrostatic image development of multiple colors. It contains at least yellow toner, magenta toner, and cyan toner as positively charged toners for electrostatic image development of the aforementioned multiple colors. All of the positively charged toners for electrostatic image development of the various colors are positively charged toners for electrostatic image development according to any one of claims 1 to 7.

9. An image forming method, wherein the image is formed using the toner group of claim 8.

Images