Magenta toner and method for producing the same

Abstract

The present invention provides a magenta toner and a method for producing the same. The magenta toner has a brighter color than before even in a small amount, has a high reflection density, and has an excellent balance between low-temperature fixability and heat-resistant storage properties, and further has excellent printing durability and few coarse particles. The magenta toner is characterized in that it contains a binder resin and a magenta colorant, and the magenta colorant includes a magenta pigment A obtained by surface-treating a pigment represented by the following formula (1) with a rosin acid metal salt, wherein the content of the magenta pigment A is 1 to 5 parts by mass relative to 100 parts by mass of the binder resin, and the content of the rosin acid metal salt is 1 to 7 parts by mass relative to 100 parts by mass of the magenta pigment A. #imgabs0# (In formula (1), Me represents a divalent metal.)

Description

Technical Field

[0001] The present invention relates to a magenta toner which exhibits a brighter color than before even in a small amount, has a high reflection density, is well balanced between low-temperature fixability and heat-resistant storage stability, has excellent printing durability, and has few coarse particles, and a method for producing the same. Background Art

[0002] In image forming devices such as electronic photographic devices and electrostatic recording devices, the electrostatic latent image formed on the photosensitive body is first developed by a toner. Next, the formed toner image is transferred to a transfer material such as paper as required, and then fixed by various methods such as heating, pressurization, or solvent vapor. Among such image forming devices, digital full-color copiers and digital full-color printers are being put into practical use. After the digital full-color copier separates the color image manuscript through each filter of blue, green and red, it uses each toner of yellow, magenta, cyan and black to develop the electrostatic latent image formed by the dot diameter of 20 to 70 μm corresponding to the original color manuscript, and forms a full-color image by using the subtractive color mixing effect.

[0003] In recent years, the demand for high quality and high resolution of full-color images has become increasingly higher. In particular, in order to improve color reproducibility, it is desired to be able to print with the same hue as printing using ink. To date, quinacridone pigments, thioindigo pigments, xanthene pigments, monoazo pigments, perylene pigments, and diketopyrrolopyrrole pigments are known to be used in magenta toners.

[0004] Patent Document 1 discloses a toner for electrostatic latent image development, characterized in that the toner is formed by fusing resin particles and colorant particles in an aqueous medium, and in the toner, the colorant contained in the colorant particles is at least selected from any one of Pigment Red 48:1, Pigment Red 48:2, Pigment Red 48:3, Pigment Red 48:4, and Pigment Red 48:5. Patent Document 1 states that such a toner is a toner for electrostatic latent image development that does not change color during heat fixing.

[0005] Furthermore, there is known an example in which toner characteristics are improved by combining an azo lake pigment with a dye.

[0006] Patent Document 2 discloses a magenta toner for color electrophotography containing a compound classified as CI Disperse Violet 31 and an azo lake pigment. Patent Document 2 states that a vivid magenta color can be obtained by using these azo lake pigments in combination with dyes.

[0007] Patent Document 3 discloses a toner for electrostatic development, characterized in that, in the toner for electrostatic development using a binder resin and a polyvalent metal salt-treated azo lake pigment of rosin acid as essential components, a polyvalent metal salt-treated azo lake pigment of rosin acid having a contact angle with water in the range of 85° to 110° is used as the polyvalent metal salt-treated azo lake pigment of rosin acid. Patent Document 3 states that: Since the contact angle of the polyvalent metal salt-treated azo lake pigment of rosin acid is 85° to 110°, the pigment dispersibility becomes better, and the transparency and charging stability also become better than when the existing azo lake pigment is used.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2002-31918;

[0011] Patent document 2: Japanese Patent Application Publication No. 63-129355;

[0012] Patent document 3: Japanese Patent Application Publication No. 2003-122055. Summary of the invention

[0013] Problem that the invention aims to solve

[0014] As an electronic photographic image forming device, its use is expanding from being used as a common copier or printer for printing documents in the office and simple copying to the field of printed matter production outside the office. Specifically, since it can simply print variable information from electronic data, its use is expanding to the Print On Demand (POD) market in the field of light printing. Therefore, in recent years, the requirements for the saturation and reflection density of printed matter have increased rapidly.

[0015] However, the magenta toners disclosed in Patent Documents 1 to 3 cannot be said to be applicable to the above-mentioned various uses for various reasons described below.

[0016] First, Patent Document 1 discloses the results of experiments using CI Pigment Red 48:3, CI Pigment Red 48:1, and CI Pigment Red 48:4 in suspension polymerization toners (Colored Particle Production Examples 9 to 11). However, according to the inventors' research, it has been found that depending on the source and type of these pigments, when they are directly supplied to suspension polymerization, a large number of coarse particles are generated.

[0017] Next, the dye used in the technique of Patent Document 2 is different from a pigment in that it is soluble in a solvent and is generally not light-resistant. Therefore, when a dye and a pigment are combined, there is a problem that light resistance may be reduced.

[0018] Next, CI Pigment Red 57:1 treated with a rosin-based polyvalent metal salt is used in the toner of Patent Document 3. However, according to the inventors' research, when such a pigment is subjected to suspension polymerization, a large number of coarse particles are generated.

[0019] In order to be applicable to the above-mentioned various uses, the requirements for the saturation and reflection density of printed materials have been rapidly increasing in recent years. In order to cope with such high requirements, the present invention aims to provide a magenta toner and a method for producing the same, wherein the magenta toner has a brighter color than before, a high reflection density, an excellent balance between low-temperature fixability and heat-resistant storage properties, and thus has excellent printing durability.

[0020] Solutions for solving problems

[0021] The inventors conducted intensive studies to achieve the above-mentioned purpose and found that by using magenta pigment A prepared by a specific surface treatment as a magenta colorant, a magenta toner having higher reflection density and saturation than before, an excellent balance between low-temperature fixing property and heat-resistant storage property, and excellent printing durability and less coarse particles can be obtained, thereby completing the present invention.

[0022] That is, the magenta toner of the present invention is characterized in that it is a magenta toner containing a binder resin and a magenta colorant, wherein the magenta colorant includes a magenta pigment A obtained by surface-treating a pigment represented by the following formula (1) with a rosin acid metal salt, the content of the magenta pigment A is 1 to 5 parts by mass relative to 100 parts of the binder resin, and 100 parts by mass of the magenta pigment A contains 1 to 7 parts by mass of the rosin acid metal salt.

[0023] [Chemical formula 1]

[0024]

[0025] (In formula (1), Me represents a divalent metal.)

[0026] In the present invention, the acid value of the magenta pigment A is 2.4 mgKOH / g or less.

[0027] In the present invention, CI Pigment Violet 19 may be contained as the magenta coloring agent.

[0028] In the present invention, CI Pigment Red 122 may be contained as the magenta colorant.

[0029] The manufacturing method of the present invention is characterized in that it is a method for manufacturing the above-mentioned magenta colorant, comprising: a step of preparing a polymerizable monomer composition containing a polymerizable monomer and the above-mentioned magenta colorant; a step of dispersing the above-mentioned polymerizable monomer composition in an aqueous medium containing a dispersion stabilizer; and a step of forming colored resin particles by supplying the above-mentioned polymerizable monomer composition to a polymerization reaction in the presence of a polymerization initiator.

[0030] Effects of the Invention

[0031] As described above, according to the present invention, by using a specific amount of magenta pigment A subjected to the specific surface treatment described above, it is possible to provide a magenta toner that exhibits a brighter color than before even with a small amount of toner, has a high reflection density, and has an excellent balance between low-temperature fixing property and heat-resistant storage property, and further has excellent printing durability and few coarse particles. DETAILED DESCRIPTION

[0032] The magenta toner of the present invention is characterized in that it is a magenta toner containing a binder resin and a magenta colorant, wherein the magenta colorant comprises a magenta pigment A obtained by surface-treating a pigment represented by the following formula (1) with a rosin acid metal salt, wherein the content of the magenta pigment A is 1 to 5 parts by mass relative to 100 parts by mass of the binder resin, and 100 parts by mass of the magenta pigment A contains 1 to 7 parts by mass of the rosin acid metal salt.

[0033] [Chemical formula 2]

[0034]

[0035] (In formula (1), Me represents a divalent metal.)

[0036] Hereinafter, the magenta toner of the present invention may be simply referred to as “toner”.

[0037] Hereinafter, a method for producing colored resin particles preferably used in the present invention, colored resin particles obtained by the production method, and a magenta toner of the present invention obtained by using the colored resin particles will be described in order.

[0038] 1. Method for producing colored resin particles

[0039] In general, the production methods of colored resin particles are roughly divided into dry methods such as pulverization and wet methods such as emulsion polymerization coagulation, suspension polymerization, and dissolution suspension. Wet methods are preferred because they can easily obtain toners with excellent printing properties such as image reproducibility. Among wet methods, polymerization methods such as emulsion polymerization coagulation and suspension polymerization are preferred because they can easily obtain toners with a small particle size distribution in the micron order. Among the polymerization methods, suspension polymerization is more preferred.

[0040] The emulsion polymerization coagulation method is to polymerize the emulsified polymerizable monomer to obtain a resin particle emulsion, and then coagulate it with a colorant dispersion liquid to produce colored resin particles. In addition, the dissolution suspension method is a method of forming droplets of a solution in which a binder resin, a colorant and other toner components are dissolved or dispersed in an organic solvent in an aqueous medium, and removing the organic solvent to produce colored resin particles, and each of the methods can be used.

[0041] The colored resin particles used in the present invention can be produced by a wet method or a dry method, preferably a wet method, and particularly preferably a suspension polymerization method. The colored resin particles can be produced by the following process.

[0042] (A) Suspension polymerization

[0043] (A-1) Preparation step of polymerizable monomer composition

[0044] First, a polymerizable monomer, a magenta colorant, and other additives such as a charge control agent and a release agent as required are mixed to prepare a polymerizable monomer composition. Mixing in preparing the polymerizable monomer composition is performed using, for example, a media disperser.

[0045] The polymerizable monomer of the present invention refers to a monomer having a functional group that can be polymerized, and the polymerizable monomer is polymerized to form a binder resin. As the main component of the polymerizable monomer, a monovinyl monomer is preferably used. As the monovinyl monomer, for example, styrene; styrene derivatives such as vinyl toluene and α-methylstyrene; acrylic acid and methacrylic acid; 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; nitrile compounds such as acrylonitrile and methacrylonitrile; amide compounds such as acrylamide and methacrylamide; olefins such as ethylene, propylene and butene. These monovinyl monomers can be used alone or in combination of two or more. Among these, as the monovinyl monomer, styrene, styrene derivatives and derivatives of acrylic acid or methacrylic acid are preferably used.

[0046] In order to improve thermal excursion and storage properties, it is preferred to use monovinyl monomers and any cross-linking polymerizable monomers. A cross-linking polymerizable monomer refers to a monomer having two or more polymerizable functional groups. Examples of cross-linking polymerizable monomers include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and its derivatives; ester compounds in which an alcohol having two or more hydroxyl groups and two or more carboxylic acids form an ester bond, such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; other divinyl compounds such as N,N-divinylaniline and divinyl ether; compounds having three or more vinyl groups, etc. These cross-linking polymerizable monomers can be used alone or in combination of two or more.

[0047] In the present invention, the cross-linkable polymerizable monomer is used in an amount of usually 0.1 to 5 parts by mass, preferably 0.3 to 2 parts by mass, based on 100 parts by mass of the monovinyl monomer.

[0048] The toner of the present invention contains a magenta pigment A obtained by surface-treating the pigment represented by the above formula (1) with a rosin acid metal salt as a magenta colorant. The magenta pigment A is obtained by surface-treating the pigment represented by the above formula (1) with a rosin acid metal salt.

[0049] The pigment represented by the above formula (1) can be classified as a so-called lake pigment. Lake pigments are pigments that are insolubilized by reacting a dye with a metal salt. Since lake pigments are cheaper than other pigments, there is an advantage that the use of lake pigments can reduce the manufacturing cost of the colorant. However, although the existing lake pigments containing the pigment represented by the above formula (1) have been insolubilized, their water solubility is still high. Therefore, when the existing lake pigments are supplied to a polymerization reaction (for example, a suspension polymerization reaction), there are the following problems: the lake pigment will dissolve in an aqueous medium, or the formation of droplets containing the lake pigment will become unstable, and the droplets will easily coagulate with each other.

[0050] In the present invention, a pigment represented by the following formula (1) is surface-treated with a rosin acid metal salt to obtain a magenta pigment A. By using the magenta pigment A, since the above-mentioned problems of conventional lake pigments do not occur, a magenta toner with less coarse particles can be produced. In addition, the obtained magenta toner exhibits a more vivid color than before even in a small amount, has a high reflection density, and has an excellent balance between low-temperature fixability and heat-resistant storage properties, thereby having excellent printing durability.

[0051] Examples of the pigment represented by the above formula (1) include Me in the above formula (1): ++ For Ba ++ CI Pigment Red 48: 1, Me in the above formula (1) ++ Ca++ CI Pigment Red 48: 2, Me in the above formula (1) ++ For Sr ++ CI Pigment Red 48: 3, Me in the above formula (1) ++ Mn ++ CI Pigment Red 48: 4, Me in the above formula (1) ++ Mg ++ CI Pigment Red 48:5 and Me in the above formula (1) ++ Cd ++ CI Pigment Red 48:6, etc. Among them, Me in the above formula (1) is preferred. ++ For Sr ++ CI Pigment Red 48:3 (CAS No. 15782-05-5). That is, the above-mentioned magenta pigment A is preferably classified as a pigment of CI Pigment Red 48:3, and CI Pigment Red 48:3 is a pigment surface-treated with a rosin acid metal salt.

[0052] The above-mentioned magenta pigment A can be a commercial product or a pre-synthesized magenta pigment A. Examples of commercial products of magenta pigment A include product name: NO.5500ST-RED (pigment classification: CI Pigment Red 48:3, content of rosin acid metal salt relative to 100 parts by mass of magenta pigment A: 5.0 parts by mass), product name: S-7014RED (pigment classification: CI Pigment Red 48:3, content of rosin acid metal salt relative to 100 parts by mass of magenta pigment A: 3.0 parts by mass), etc. manufactured by Daido Chemical Corporation.

[0053] When synthesizing the above-mentioned magenta pigment A, for example, when synthesizing a dye for the pigment (lake pigment) represented by the above-mentioned formula (1), the above-mentioned magenta pigment A can be obtained by synthesizing the above-mentioned magenta pigment A through a coupling reaction using a coupler component containing a rosin acid metal salt, and then lake-forming the obtained dye. The above-mentioned magenta pigment A can be produced by, for example, contacting the pigment represented by the above-mentioned formula (1) as a raw material with a rosin acid metal salt.

[0054] Here, the rosin acid may include any known and commonly used rosin acids, such as rosin acids with abietic acid as the main component, disproportionated rosin acids, partially hydrogenated rosin acids, fully hydrogenated rosin acids, maleic acid-modified rosin acids, fumaric acid-modified rosin acids, polymerized rosin acids, etc. As the rosin acid, a low-acid rosin acid having an acid value of 170 mgKOH / g or less, preferably 100 mgKOH / g or less may be used. By using this low-acid rosin acid, the acid value of the magenta pigment A can be reduced, and as a result, the generation of coarse particles can be suppressed.

[0055] Abietic acid metal salt refers to a salt of abietic acid and a divalent, trivalent or tetravalent polyvalent metal, such as Ca salt, Ba salt, Sr salt, Al salt, Zn salt, etc. As the abietic acid metal salt, Sr salt of abietic acid is preferably included, because it has a high effect of improving the brushing property in the toner manufacturing process.

[0056] The content of the rosin acid metal salt is usually 1 to 7 parts by mass, preferably 2 to 6 parts by mass, and more preferably 2.5 to 5.5 parts by mass relative to 100 parts by mass of the magenta pigment A. By setting the above-mentioned addition amount of the rosin acid metal salt to 1 to 7 parts by mass, the liberation of the rosin acid metal salt is suppressed, and thus there is no free rosin acid metal salt or its derivative to hinder the production of the toner, so a toner with less coarse particles can be obtained. In addition, the content of the magenta pigment A can be obtained as the total content of the pigment represented by the above formula (1) used as a raw material and the rosin acid metal salt as a surface treatment agent.

[0057] The acid value of the magenta pigment A is not particularly limited, and is usually 3 mgKOH / g or less, preferably 2.4 mgKOH / g or less, more preferably 0.1 to 2.0 mgKOH / g, and more preferably 0.3 to 1.0 mgKOH / g, and even more preferably 0.4 to 0.8 mgKOH / g, from the viewpoint of significantly inhibiting the generation of coarse particles. The acid value of the magenta pigment A can be adjusted according to, for example, the type and addition amount of the rosin acid metal salt. For example, by using the above-mentioned low acid value rosin acid metal salt as the rosin acid metal salt, the acid value of the magenta pigment A can be 1.0 mgKOH / g or less.

[0058] In addition, the acid value in the present invention can be measured in accordance with JIS K0070.

[0059] The content of the magenta pigment A is 1 to 5 parts by mass, preferably 1.5 to 4.5 parts by mass, and more preferably 2 to 4 parts by mass relative to 100 parts by mass of the binder resin. By making the above content of the magenta pigment A 1 part by mass or more, a toner can be obtained that has a brighter color than before even with a small amount of toner, has a high reflection density, and has an excellent balance between low-temperature fixability and heat-resistant storage properties, and thus has excellent printing durability. By making the above content of the magenta pigment A 5 parts by mass or less, since there is no excessive magenta pigment A to hinder the production of the toner, a toner with fewer coarse particles can be obtained.

[0060] As the magenta coloring agent that can be used in combination with magenta pigment A, CI Pigment Red 31, CI Pigment Red 122 (CAS No.980-26-7), CI Pigment Red 146, CI Pigment Red 150, CI Pigment Red 180, CI Pigment Red 185, CI Pigment Red 238, CI Pigment Violet 19 (CAS No.1047-16-1) etc. can be enumerated. By using these magenta coloring agents in combination with magenta pigment A, the printing durability can be further improved, and the generation of coarse particles can be further suppressed. Among these, the magenta coloring agent that can be used in combination with magenta pigment A is preferably CI Pigment Red 122 and CI Pigment Violet 19.

[0061] When Magenta Pigment A and CI Pigment Red 122 are combined as a magenta colorant, a magenta toner that exhibits a more vivid color than before and has a high reflection density can be realized at a lower cost than before even with a small amount of toner.

[0062] The content of CI Pigment Red 122 is usually 1 to 5 parts by mass, preferably 1.5 to 4.5 parts by mass, and more preferably 2 to 4 parts by mass relative to 100 parts by mass of the binder resin. By setting the content of CI Pigment Red 122 to 1 to 5 parts by mass, magenta pigment A and CI Pigment Red 122 can be balanced, and a brighter color and a higher reflection density can be obtained.

[0063] When Magenta Pigment A and CI Pigment Violet 19 are combined as a magenta colorant, a magenta toner that exhibits a more vivid color than before and has a high reflection density even with a small toner amount can be realized at a lower cost than before.

[0064] The content of CI Pigment Violet 19 is usually 1 to 5 parts by mass, preferably 1.5 to 4.5 parts by mass, and more preferably 2 to 4 parts by mass relative to 100 parts by mass of the binder resin. By setting the content of CI Pigment Violet 19 to 1 to 5 parts by mass, magenta pigment A and CI Pigment Violet 19 can be balanced, and a brighter color and a higher reflection density can be obtained.

[0065] The magenta toner of the present invention may contain Magenta Pigment A, CI Pigment Red 122, and CI Pigment Violet 19 as magenta colorants.

[0066] Different raw materials may be used for CI Pigment Violet 19 and CI Pigment Red 122, or a colorant composition containing these materials may be used. As the colorant composition, for example, a mixed crystal of CI Pigment Violet 19 and CI Pigment Red 122 may be mentioned.

[0067] In order to improve weather resistance and image density and further suppress the generation of coarse particles, CI Pigment Violet 19 can be used as a mixed crystal with CI Pigment 122. That is, the magenta colorant used in the present invention can contain a mixed crystal of CI Pigment Red 122 and CI Pigment Violet 19 and magenta pigment A.

[0068] The mixed crystal 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 in which the mixed crystal components are simultaneously recrystallized from sulfuric acid or other appropriate solvents and, after grinding as needed, treated with a solvent, or the method described in German Patent Application Publication No. 1,217,333 in which a substituted diaminoterephthalic acid mixture is treated with a solvent after cyclization.

[0069] The usage ratio of CI Pigment Red 122 and CI Pigment Violet 19 is usually 80:20 to 20:80, preferably 70:30 to 30:70, and more preferably 60:40 to 40:60, in terms of mass ratio (CI Pigment Red 122:CI Pigment Violet 19).

[0070] When two or more magenta colorants are used, the total content of the magenta colorants is generally 2 to 10 parts by mass, preferably 3 to 9 parts by mass, and more preferably 4 to 8 parts by mass relative to 100 parts by mass of the binder resin. By making the above-mentioned total content of the magenta colorant 2 to 10 parts by mass, the obtained toner shows a higher reflection density and saturation, and the balance between low-temperature fixability and heat-resistant storage is improved, thereby obtaining excellent printing durability. Among them, from the viewpoint of significantly suppressing the formation of coarse particles and improving the low-temperature fixability, the total content of the magenta colorant is preferably 7 parts by mass or less, and more preferably 6 parts by mass or less relative to 100 parts by mass of the binder resin.

[0071] Furthermore, when two or more magenta colorants are used, the ratio of magenta pigment A to other magenta pigments different from magenta pigment A is not particularly limited, but is preferably 70:30 to 30:70, more preferably 60:40 to 40:60, and even more preferably 55:45 to 45:55 in terms of mass ratio (magenta pigment A: other magenta pigments) from the viewpoint of obtaining a brighter color and a higher reflection density, from the viewpoint of suppressing the formation of coarse particles, and from the viewpoint of improving printing durability and low-temperature fixing property.

[0072] As other additives, a positively or negatively chargeable charge control agent may be used in order to improve the chargeability of the toner.

[0073] As a charge control agent, there is no particular limitation as long as it can be used as a charge control agent for colorants. Among the charge control agents, positively or negatively charged charge control resins are preferred due to their high solubility with polymerizable monomers and their ability to impart stable charge (charge stability) to colorant particles. Furthermore, from the viewpoint of obtaining a positively charged colorant, it is more preferred to use a positively charged charge control resin.

[0074] Examples of positively charged charge control agents include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds, imidazole compounds, and charge control resins such as polyamine resins, quaternary ammonium group-containing copolymers, and quaternary ammonium salt group-containing copolymers. Among these, the above-mentioned charge control resins are preferred.

[0075] As negatively charged charge control agents, there can be mentioned azo dyes containing metals such as Cr, Co, Al and Fe, salicylic acid metal compounds, alkyl salicylic acid metal compounds, and charge control resins such as sulfonic acid group-containing copolymers, sulfonate group-containing copolymers, carboxylic acid group-containing copolymers and carboxylate group-containing copolymers. Among these, the above-mentioned charge control resins are preferred.

[0076] In the present invention, the charge control agent is usually used in a ratio of 0.01 to 10 parts by mass, preferably 0.03 to 8 parts by mass, relative to 100 parts by mass of the monovinyl monomer. When the amount of the charge control agent added is less than 0.01 parts by mass, fogging may sometimes occur. On the other hand, when the amount of the charge control agent added exceeds 10 parts by mass, printing contamination may sometimes occur.

[0077] When the polymerizable monomer is polymerized to form the binder resin, it is preferable to use a molecular weight modifier as another additive.

[0078] The molecular weight modifier is not particularly limited as long as it can be used as a molecular weight modifier for toner, and examples thereof include mercaptans such as tert-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2,4,6,6-pentamethylheptane-4-mercaptan; thiuram disulfides such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N,N'-dimethyl-N,N'-diphenylthiuram disulfide, and N,N'-dioctadecyl-N,N'-diisopropylthiuram disulfide, etc. These molecular weight modifiers can be used alone or in combination of two or more.

[0079] In the present invention, the molecular weight modifier is usually used in an amount of 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the monovinyl monomer.

[0080] Furthermore, as other additives, it is preferred to add a release agent. By adding a release agent, the releasability of the toner from the fixing roller during fixing can be improved. As a release agent, generally, as long as it is a release agent that can be used for the toner, it can be used without particular restrictions. For example, low molecular weight polyolefin wax, its modified wax; petroleum wax such as paraffin; mineral wax such as ozokerite; synthetic wax such as Fischer-Tropsch wax; ester wax such as dipentaerythritol ester and carnauba, etc. can be cited. From the perspective of achieving a balance between the storage stability and low-temperature fixing property of the toner, ester wax is preferred, and synthetic ester wax obtained by esterifying alcohol and carboxylic acid is more preferred, among which synthetic ester wax in which the alcohol is a polyol and the carboxylic acid is a monocarboxylic acid is further preferred. They can be used alone or in combination of two or more.

[0081] The release agent is preferably used in an amount of 1 to 30 parts by mass, more preferably 5 to 20 parts by mass, based on 100 parts by mass of the monovinyl monomer.

[0082] (A-2) Suspension step of obtaining a suspension (droplet formation step)

[0083] In the present invention, a polymerizable monomer composition containing a polymerizable monomer and a magenta colorant is dispersed in an aqueous medium containing a dispersion stabilizer, and after a polymerization initiator is added, droplets of the polymerizable monomer composition are formed. The droplet formation method is not particularly limited, and is carried out using a device capable of strong stirring, such as an (inline type) emulsifying disperser (manufactured by Pacific Machinery & Engineering Co., Ltd., trade name: Milder), a high-speed emulsifying disperser (manufactured by PRIMIX Corporation, trade name: TKHOMOMIXER MARK II type), etc.

[0084] As polymerization initiators, persulfates such as potassium persulfate and ammonium persulfate can be cited; azo compounds such as 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), 2,2'-azobis(2-aminopropane) dihydrochloride, 2,2'-azobis(2,4-dimethylvaleronitrile) and 2,2'-azobisisobutyronitrile; organic peroxides such as di-tert-butyl peroxide, benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxy-2-ethylbutyrate, tert-hexyl peroxy-2-ethylbutyrate, diisopropyl peroxydicarbonate, di-tert-butyl peroxyisophthalate and tert-butyl peroxyisobutyrate. They can be used alone or in combination of two or more. Among these, organic peroxides are preferably used because they can reduce residual polymerizable monomers and have excellent printing durability.

[0085] Among organic peroxides, peroxyesters are preferred, and non-aromatic peroxyesters, ie, peroxyesters having no aromatic ring, are more preferred, because of their high initiator efficiency and the ability to reduce residual polymerizable monomers.

[0086] As described above, the polymerization initiator may be added after the polymerizable monomer composition is dispersed in the aqueous medium and before droplets are formed, or may be added to the polymerizable monomer composition before it is dispersed in the aqueous medium.

[0087] The amount of the polymerization initiator used in the polymerization reaction of the polymerizable monomer composition is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 15 parts by mass, and particularly preferably 1 to 10 parts by mass, based on 100 parts by mass of the monovinyl monomer.

[0088] In the present invention, the aqueous medium refers to a medium containing water as a main component.

[0089] In the present invention, it is preferred that the aqueous medium contains a dispersion stabilizer. Examples of the dispersion stabilizer 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 aluminum oxide and titanium oxide; inorganic compounds such as metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and iron hydroxide; water-soluble polymers such as polyvinyl alcohol, methylcellulose, and gelatin; anionic surfactants; nonionic surfactants; organic compounds such as amphoteric surfactants. These dispersion stabilizers can be used alone or in combination of two or more.

[0090] Among the above-mentioned dispersion stabilizers, inorganic compounds are preferred, and as the aqueous medium containing the dispersion stabilizer, a colloid of a sparingly water-soluble metal hydroxide is particularly preferred. By using an inorganic compound, particularly a colloid of a sparingly water-soluble metal hydroxide, the particle size distribution of the colored resin particles can be narrowed, and further, since the amount of the dispersion stabilizer remaining after washing can be reduced, the obtained polymerized toner can reproduce images clearly without deteriorating the environmental stability.

[0091] (A-3) Polymerization step

[0092] As in the above (A-2), after the droplets of the polymerizable monomer composition are formed, the polymerizable monomer composition is subjected to a polymerization reaction in the presence of a polymerization initiator to form colored resin particles. That is, the aqueous dispersion medium in which the droplets of the polymerizable monomer composition are dispersed is heated to initiate polymerization, thereby forming an aqueous dispersion of colored resin particles containing a magenta colorant.

[0093] The polymerization temperature of the polymerizable monomer composition is preferably 50° C. or higher, more preferably 60 to 95° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

[0094] The colored resin particles can be used as a polymerized toner directly or by adding an external additive. It is preferable to use the colored resin particles as the core layer of a so-called core-shell type (or also called "capsule type") colored resin particle. The core-shell type colored resin particle has a structure in which the outer side of the core layer is covered with a shell layer formed of a material different from the core layer. By covering the core layer formed of a material having a low softening point with a material having a higher softening point than the core layer, a balance can be achieved between lowering the fixing temperature of the toner and preventing aggregation during storage.

[0095] The method for producing the core-shell type colored particles using the colored resin particles is not particularly limited, and the core-shell type colored particles can be produced by a conventionally known method. In terms of production efficiency, an in situ polymerization method or a phase separation method is preferred.

[0096] A method for producing core-shell type colored resin particles by in-situ polymerization will be described below.

[0097] Core-shell type colored resin particles can be obtained by adding a polymerizable monomer for forming a shell layer (shell polymerizable monomer) and a polymerization initiator to an aqueous medium in which the colored resin particles are dispersed and polymerizing the mixture.

[0098] As the polymerizable monomer for the shell, the same polymerizable monomer as described above can be used. Among them, monomers that can give a polymer having a Tg exceeding 80° C., such as styrene, acrylonitrile, and methyl methacrylate, are preferably used alone or in combination of two or more.

[0099] As polymerization initiators used for polymerization of the polymerizable monomers for shells, metal persulfates such as potassium persulfate and ammonium persulfate; azo initiators such as 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide) and 2,2'-azobis-(2-methyl-N-(1,1-bis(hydroxymethyl)2-hydroxyethyl)propionamide) and other water-soluble polymerization initiators can be cited. These can be used alone or in combination of two or more. The amount of the polymerization initiator is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, relative to 100 parts by mass of the polymerizable monomers for shells.

[0100] The polymerization temperature of the shell layer is preferably 50° C. or higher, more preferably 60 to 95° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

[0101] (A-4) Cleaning, filtration, dehydration and drying process

[0102] The aqueous dispersion of the colored resin particles obtained by polymerization is preferably subjected to filtration, washing to remove the dispersion stabilizer, dehydration, and drying, preferably repeated several times according to a conventional method after completion of the polymerization.

[0103] As the above-mentioned cleaning method, it is preferred that when an inorganic compound is used as a dispersion stabilizer, an acid or an alkali is added to the aqueous dispersion of the colored resin particles, thereby dissolving the dispersion stabilizer in water and removing it. When a colloid of a poorly water-soluble inorganic hydroxide is used as a dispersion stabilizer, it is preferred to add an acid to adjust the pH of the aqueous dispersion of the colored resin particles to 6.5 or less. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid and organic acids such as formic acid and acetic acid can be used. Sulfuric acid is particularly preferred because of its high removal efficiency and small burden on manufacturing equipment.

[0104] The dehydration and filtration methods can use various known methods, etc., and are not particularly limited. For example, centrifugal filtration, vacuum filtration, pressure filtration, etc. can be cited. In addition, the drying method is not particularly limited either, and various methods can be applied.

[0105] (B) Crushing method

[0106] When the colored resin particles are produced by a pulverization method, the production can be carried out, for example, by the following process.

[0107] First, use a mixer, such as a ball mill, a V-type mixer, an FM mixer (trade name), a high-speed dissolver, a Banbury mixer, Forberg, etc., to mix a bonding resin, a fuchsin coloring agent, and other additives such as a charge control agent and a release agent that are added as required. Then, use a pressurized kneader, a twin-screw extruder mixer, a roller, etc. to heat and mix. Use pulverizers such as a hammer mill, a cutter, and a roller mill to coarsely pulverize the resulting mixture. And then, after using pulverizers such as a jet mill and a high-speed rotary pulverizer to finely pulverize, the particle size is classified into a desired particle size by a classifier such as a wind classifier and an airflow classifier, and the colored resin particles utilizing a pulverization method are obtained.

[0108] In addition, the binder resin, magenta colorant, and other additives such as the charge control agent and the release agent used in the pulverization method as well as those listed in the above-mentioned (A) suspension polymerization method can be used. In addition, like the colored resin particles obtained by the above-mentioned (A) suspension polymerization method, the colored resin particles obtained by the pulverization method can also be used to manufacture core-shell colored resin particles using a method such as an in-situ polymerization method.

[0109] As the binder resin, other than these, resins widely used in toners can be used. Specific examples of the binder resin used in the pulverization method include polystyrene, styrene-butyl acrylate copolymer, polyester resin, and epoxy resin.

[0110] 2. Colored resin particles

[0111] Colored resin particles containing a magenta colorant can be obtained by the production method such as the above-mentioned (A) suspension polymerization method or (B) pulverization method.

[0112] The colored resin particles constituting the toner are described below. The colored resin particles described below include both core-shell type and non-core-shell type.

[0113] The volume average particle size (Dv) of the colored resin particles is preferably 3 to 15 μm, and more preferably 4 to 12 μm. When Dv is less than 3 μm, the fluidity of the toner may be reduced, the transferability may be deteriorated, and the image density may be reduced. When Dv exceeds 15 μm, the resolution of the image may be reduced.

[0114] In addition, the ratio (Dv / Dn) of the volume average particle size (Dv) to the number average particle size (Dn) of the colored resin particles is preferably 1.0 to 1.3, and more preferably 1.0 to 1.2. When Dv / Dn exceeds 1.3, the transferability, image density, and resolution may be reduced. The volume average particle size and number average particle size of the colored resin particles can be measured using, for example, a particle size analyzer (manufactured by Beckman Coulter, Inc., trade name: Multisizer).

[0115] From the viewpoint of image reproducibility, the average circularity of the colored resin particles of the present invention is preferably from 0.96 to 1.00, more preferably from 0.97 to 1.00, and even more preferably from 0.98 to 1.00.

[0116] When the average circularity of the colored resin particles is less than 0.96, the reproducibility of printed thin lines may be deteriorated.

[0117] 3. Toner of the present invention

[0118] The colorant of the present invention can also use the colored resin particles containing the above-mentioned magenta colorant directly as the colorant. From the viewpoint of adjusting the chargeability, fluidity and storage stability of the colorant, the above-mentioned colored resin particles can be mixed and stirred with an external additive to perform an external addition treatment, thereby making the external additive adhere to the surface of the colored resin particles to prepare a single-component colorant.

[0119] In addition, the single-component toner can be further mixed and stirred with carrier particles to produce a two-component developer.

[0120] The agitator for performing the external addition treatment is not particularly limited as long as it is a stirring device that can make the external additive adhere to the surface of the colored resin particles. For example, a stirrer capable of mixing and stirring, such as FMmixer (trade name, manufactured by Nippon Coke & Engineering Co., Ltd.), Supermixer (trade name, manufactured by Kawada Manufacturing Co., Ltd.), Qmixer (trade name, manufactured by Nippon Coke & Engineering Co., Ltd.), Mechano Fusion System (trade name, manufactured by Hosokawa MicroGroup) and Mechanomill (trade name, manufactured by OKADA SEIKO.CO.,LTD.), can be used for the external addition treatment.

[0121] As external additives, there can be mentioned inorganic particles such as silicon dioxide, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate and cerium oxide; organic particles such as polymethyl methacrylate resin, silicone resin and melamine resin, etc. Among these, inorganic particles are preferred, and among the inorganic particles, at least one particle selected from silicon dioxide and titanium oxide is preferred, and particles containing silicon dioxide are particularly preferred.

[0122] These external additives may be used alone, or two or more kinds thereof may be used in combination.

[0123] In the present invention, the external additive is usually used in a ratio of 0.05 to 6 parts by mass, preferably 0.2 to 5 parts by mass, relative to 100 parts by mass of the colored resin particles. When the amount of the external additive added is less than 0.05 parts by mass, transfer residue may occur. When the amount of the external additive added exceeds 6 parts by mass, fog may occur.

[0124] The toner of the present invention obtained through the above steps uses a specific amount of the above magenta pigment, and thus exhibits a brighter color than conventional toners even with a small amount of toner, has a high reflection density, and has an excellent balance between low-temperature fixability and heat-resistant storage stability.

[0125] Example

[0126] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, parts and % are based on mass unless otherwise specified.

[0127] The test methods performed in the present examples and comparative examples are as follows.

[0128] 1. Manufacture of Magenta Pigment

[0129] [Production Example 1: Production of mixed crystals of magenta pigment]

[0130] 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 obtained phosphoric acid dispersion of 2,9-dimethylquinacridone, filtered and separated with a filter, and then further washed with water. Water was added to the washed 2,9-dimethylquinacridone again to prepare an aqueous dispersion with a solid content of 20%.

[0131] Similarly, 2,5-diphenylaminoterephthalic acid is used to prepare an aqueous dispersion of quinacridone (CI Pigment Violet 19) with a solid content of 20%. 250 parts of ethanol are added to 250 parts of the aqueous dispersion of dimethylquinacridone (CI Pigment Red 122) with a solid content of 20% and 250 parts of the aqueous dispersion of quinacridone (CI Pigment Violet 19) with a solid content of 20%, to prepare a mixed solution of pigments. The mixed solution is transferred to a container equipped with a cooling tube, and the pigment is ground while being reacted under heating reflux for 5 hours. After the reaction is completed, the pigment is filtered and separated from the reaction solution, washed, dried, and then crushed to obtain a mixed crystal of magenta pigment (i.e., a mixed crystal of CI Pigment Red 122 and CI Pigment Violet 19). In addition, the mass ratio of each pigment contained in the mixed crystal is CI Pigment Red 122:CI Pigment Violet 19=1:1.

[0132] [Manufacturing Example 2: Manufacture of Magenta Pigment A2]

[0133] After dispersing 20 parts of 4-chloro-6-aminosulfonic acid in 300 parts of water, 22 parts of 20% hydrochloric acid was added, ice was further added, and 25.1 parts of 30% sodium nitrite aqueous solution was added dropwise while maintaining at 0°C to obtain a diazonium salt suspension.

[0134] To 500 parts of water, 10.2 parts (equivalent to about 5% of magenta pigment A2) of a potassium salt solution of disproportionated rosin acid (acid value: 170 mgKOH / g) (purity of disproportionated rosin acid: 25%) was added. To the stirred diluted solution of the potassium salt of disproportionated rosin acid, 1.82 parts of an aqueous solution containing strontium chloride was added to obtain a suspension containing a strontium salt of disproportionated rosin acid (suspension A).

[0135] After dispersing 20.6 parts of 2-hydroxy-3-naphthoic acid in 380 parts of warm water at 60°C, 20.1 parts of a 48% aqueous caustic soda solution was added to obtain a coupling solution.

[0136] The coupling solution is added to the suspension A to prepare a coupling solution (coupler component).

[0137] After the coupling solution was cooled to 0°C, the diazonium salt suspension was added dropwise over 30 minutes while stirring, and the coupling reaction was terminated by stirring at 0 to 3°C for 60 minutes to obtain a dye suspension.

[0138] Add an aqueous solution of 20.18 parts of strontium chloride dissolved in 90 parts of water, and stir for 60 minutes to terminate the lake reaction. After the lake reaction is completed, heat at 30°C for 60 minutes while stirring to obtain a suspension in water of a strontium azo lake pigment (CI Pigment Red 48:3) surface-treated with a strontium salt of disproportionated rosin acid. Then, heat to 60°C and stir for 60 minutes. After adjusting the pH to 7.6 with hydrochloric acid, filter and wash to separate the wet cake containing the pigment. Dry the separated wet cake to obtain a powder of red magenta pigment A2.

[0139] [Manufacturing Example 3: Manufacture of Magenta Pigment A3]

[0140] Magenta Pigment A3 was obtained in the same manner as in Production Example 2 except that disproportionated rosin acid (acid value: 170 mgKOH / g) was changed to disproportionated rosin acid (acid value: 100 mgKOH / g).

[0141] [Determination of pigment acid value]

[0142] The acid values ​​of magenta pigment A1 (manufactured by DAITO KASEI KOGYO CO., LTD., product name: No. 5500ST-RED, pigment classification: CI Pigment Red 48:3), magenta pigment A2 obtained in the above-mentioned Production Example 2, magenta pigment A3 obtained in the above-mentioned Production Example 3, magenta pigment X (manufactured by DAITO KASEI KOGYO CO., LTD., product name: No. 7510, pigment classification: CI Pigment Red 57:1), and magenta pigment Y (pigment classification: CI Pigment Red 48:3, content of rosin acid metal salt relative to 100 parts of magenta pigment Y: 10.0 parts) were measured in accordance with JIS K0070.

[0143] 2. Production of colored resin particles

[0144] <Colored Resin Particles (1)>

[0145] 2-1. Preparation of core polymerizable monomer composition:

[0146] 73 parts of styrene, 27 parts of n-butyl acrylate, 0.15 parts of divinylbenzene, 0.4 parts of tetraethylthiuram disulfide, 4.0 parts of magenta pigment A1 (manufactured by DAITO KASEI KOGYO CO., LTD., product name: NO.5500ST-RED, pigment classification: CI Pigment Red 48:3, content of rosin acid metal salt (Sr salt) per 100 parts of magenta pigment A1: 5.0 parts) as a magenta colorant, and 3.0 parts of CI Pigment Red 122 (CAS No.980-26-7, manufactured by Clariant AG, trade name: Toner Magenta E) were wet-pulverized using a media disperser (manufactured by ASADA IRON WORKS. CO., LTD., trade name: PICOMILL). To the mixture obtained by wet pulverization, 1.0 part of a charge control resin (quaternary ammonium salt-containing styrene-acrylic acid copolymer, copolymerization ratio of monomers having a functional group: 8%) and 9.0 parts of an ester wax (polyol ester manufactured by NOF Corporation) were added, mixed and dissolved to prepare a polymerizable monomer composition.

[0147] 2-2. Preparation of aqueous dispersion medium:

[0148] Meanwhile, an aqueous solution of 9.9 parts of sodium hydroxide in 50 parts of ion-exchanged water was gradually added to an aqueous solution of 14.1 parts of magnesium chloride in 280 parts of ion-exchanged water under stirring to prepare a magnesium hydroxide colloidal dispersion.

[0149] 2-3. Preparation of polymerizable monomers for shell:

[0150] On the other hand, 2 parts of methyl methacrylate and 130 parts of water were finely dispersed by an ultrasonic emulsifier to prepare an aqueous dispersion of a polymerizable monomer for shell.

[0151] 2-4. Granulation process:

[0152] The polymerizable monomer composition was added to the magnesium hydroxide colloidal dispersion (magnesium hydroxide colloidal amount: 7.2 parts), and further stirred, and 4.4 parts of tert-butyl peroxy-2-ethylhexanoate as a polymerization initiator were added thereto. The dispersion to which the polymerization initiator was added was dispersed at a rotation speed of 15000 rpm by an inline emulsifying disperser (Pacific Machinery & Engineering Co., Ltd., trade name: Milder) to form droplets of the polymerizable monomer composition.

[0153] 2-5. Suspension polymerization process:

[0154] The dispersion containing droplets of the polymerizable monomer composition was added to a reactor and heated to 90°C for polymerization reaction. After the polymerization conversion rate reached almost 100%, a solution in which 0.1 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] (manufactured by FUJIFILM Wako Pure Chemical Corporation, trade name: VA-086, water-soluble initiator) as a shell polymerization initiator was dissolved in the above-mentioned shell polymerizable monomer aqueous dispersion was added to the reactor. Next, the temperature was maintained at 95°C for 4 hours, and after further polymerization was continued, the reaction was terminated by water cooling to obtain an aqueous dispersion of core-shell type colored resin particles.

[0155] 2-6. Post-processing process:

[0156] While stirring the aqueous dispersion of the colored resin particles, sulfuric acid was added until the pH became 6.0 or less, and acid washing was performed (25° C., 10 minutes). The filtered and separated colored resin particles were washed with water, and the washing water was filtered. The conductivity of the filtrate at this time was 20 μS / cm. The colored resin particles after the washing and filtering steps were further dehydrated and dried to obtain dried colored resin particles (1).

[0157] <Colored Resin Particles (2)>

[0158] Colored resin particles (2) were obtained in the same manner as in the method for producing colored resin particles (1) except that the amount of magenta pigment A1 added was changed from 4.0 parts to 3.0 parts in the above “preparation of polymerizable monomer composition for core”.

[0159] <Colored Resin Particles (3)>

[0160] In the above-mentioned “Preparation of the polymerizable monomer composition for core”, the addition amount of magenta pigment A1 was changed from 4.0 parts to 3.0 parts, and 3.0 parts of CI Pigment Red 122 was changed to 3.0 parts of the mixed crystal of the magenta pigment of the above-mentioned Production Example 1. The same method as that of the production method of colored resin particles (1) was carried out to obtain colored resin particles (3).

[0161] <Colored Resin Particles (4)>

[0162] In the above-mentioned “Preparation of the polymerizable monomer composition for core”, the addition amount of magenta pigment A1 was changed from 4.0 parts to 3.0 parts, and 3.0 parts of CI Pigment Red 122 was changed to 3.0 parts of CI Pigment Violet 19 (CAS No. 1047-16-1, manufactured by Clariant AG, trade name: Ink Jet Magenta E5B02). Except for this, the same method as the method for producing colored resin particles (1) was carried out to obtain colored resin particles (4).

[0163] <Colored Resin Particles (5)>

[0164] Colored resin particles (5) were obtained in the same manner as in the method for producing colored resin particles (1) except that 4.0 parts of magenta pigment A1 was replaced with 3.0 parts of CI Pigment Red 48:3 (unsurface treated) in the above "Preparation of core polymerizable monomer composition".

[0165] <Colored Resin Particles (6)>

[0166] In the above-mentioned "Preparation of the polymerizable monomer composition for core", except that 4.0 parts of magenta pigment A1 was changed to 3.0 parts of magenta pigment X (manufactured by DAITO KASEI KOGYO CO., LTD., product name: No. 7510, pigment classification: CI Pigment Red 57:1, content of rosin acid metal salt (Sr salt) based on 100 parts of magenta pigment X: 5.0 parts), the same method as the method for producing colored resin particles (1) was carried out to obtain colored resin particles (6).

[0167] <Colored Resin Particles (7)>

[0168] In the above-mentioned "Preparation of the polymerizable monomer composition for core", except that 4.0 parts of magenta pigment A1 was changed to 3.0 parts of magenta pigment Y (pigment classification: CI Pigment Red 48:3, content of rosin acid metal salt (Sr salt) relative to 100 parts of magenta pigment Y: 10.0 parts), the same method as the method for producing colored resin particles (1) was carried out to obtain colored resin particles (7).

[0169] <Colored Resin Particles (8)>

[0170] Colored resin particles (8) were obtained in the same manner as in the method for producing colored resin particles (1) except that the amount of magenta pigment A1 added was changed from 4.0 parts to 6.0 parts in the above “preparation of core polymerizable monomer composition” and CI Pigment Red 122 was not used.

[0171] <Colored Resin Particles (9)>

[0172] In the above-mentioned "Preparation of the polymerizable monomer composition for core", the same method as the method for producing colored resin particles (1) was carried out, except that neither magenta pigment A1 nor CI Pigment Red 122 was used and 7.0 parts of the mixed crystal of the magenta pigment of the above-mentioned Production Example 1 was used, to obtain colored resin particles (9).

[0173] <Colored Resin Particles (10)>

[0174] In the above-mentioned “Preparation of the polymerizable monomer composition for core”, the same method as the method for producing colored resin particles (1) was carried out except that neither magenta pigment A1 nor CI Pigment Red 122 was used, and 3.0 parts of CI Solvent Violet 59 (CAS No. 6408-72-6, manufactured by Clariant AG, trade name: Solvaperm Red Violet R) and 3.0 parts of CI Pigment Red 146 (CAS No. 5280-68-2; manufactured by Clariant AG, trade name: Permanent Carmine FBB02) were used to obtain colored resin particles (10).

[0175] <Colored Resin Particles (11)>

[0176] Colored resin particles (11) were obtained in the same manner as in the method for producing colored resin particles (10), except that the amount of CI Pigment Red 146 added was changed from 3.0 parts to 4.0 parts.

[0177] <Colored Resin Particles (12)>

[0178] Colored resin particles (12) were obtained in the same manner as in the method for producing colored resin particles (2), except that magenta pigment A1 was changed to magenta pigment A2 obtained in Production Example 2.

[0179] <Colored Resin Particles (13)>

[0180] Colored resin particles (13) were obtained in the same manner as in the method for producing colored resin particles (2), except that magenta pigment A1 was changed to magenta pigment A3 obtained in Production Example 3.

[0181] <Colored Resin Particles (14)>

[0182] Colored resin particles (14) were obtained in the same manner as in the method for producing colored resin particles (13), except that the amount of magenta pigment A3 used was changed from 3.0 parts to 4.8 parts and CI Pigment Red 122 was not used.

[0183] 3. Manufacture of magenta toner

[0184] The colored resin particles (1) to (14) were subjected to external addition treatment to produce magenta toners of Examples 1 to 7 and Comparative Examples 1 to 7.

[0185] (Example 1)

[0186] To 100 parts of the colored resin particles (1), 0.2 parts of hydrophobized silica fine particles with an average particle size of 7 nm, 1.0 parts of hydrophobized silica fine particles with an average particle size of 22 nm, and 1.26 parts of hydrophobized silica fine particles with an average particle size of 50 nm were added and mixed using a high-speed stirrer (manufactured by Nippon Coke & Engineering Co., Ltd., trade name: FM mixer) to prepare a magenta toner of Example 1.

[0187] (Examples 2 to 7, Comparative Examples 1 to 7)

[0188] As shown in Table 1 below, magenta toners of Examples 2 to 7 and Comparative Examples 1 to 7 were obtained in the same manner as in Example 1 except that the colored resin particles (1) were changed to any one of the colored resin particles (2) to (14).

[0189] 4. Evaluation of magenta toner

[0190] As described below, the magenta toners of Examples 1 to 7 and Comparative Examples 1 to 7 were evaluated for coarse powder amount, image density, saturation, minimum fixing temperature, fog under normal temperature and humidity (N / N) environment, heat resistance temperature (storability evaluation), printing durability (durability test) and charge amount (blow-off charge amount).

[0191] 4-1. Evaluation of coarse powder amount

[0192] The coarse powder amount of the toner was evaluated by measuring the particle size distribution using a particle size analyzer (manufactured by Beckman Coulter, Inc., trade name: Multisizer). The measurement using the Multisizer was performed under the following conditions: pore size: 100 μm, dispersion medium: ISOTONII (trade name), concentration: 10%, and number of measured particles: 100,000.

[0193] The specific procedure is as follows. First, 0.2 g of a toner sample is measured in a beaker, and a surfactant aqueous solution (manufactured by FUJIFILM Corporation, trade name: DRIWEL) is added thereto as a dispersant. 2 mL of a dispersion medium is further added thereto to wet the toner, and then 10 mL of a dispersion medium is added thereto, and after being dispersed for 1 minute by an ultrasonic disperser, the particle size distribution based on volume is measured by the above-mentioned particle size distribution measuring machine.

[0194] Based on the particle size distribution obtained by the measurement, the ratio (volume %) of particles having a particle size of 20 μm or more was defined as the amount of coarse powder.

[0195] 4-2. Image density and saturation measurement

[0196] A commercially available non-magnetic single-component color printer (printing speed = 20 sheets / minute) was used to fill the toner sample of the developing device on the drum, and then the printing paper was placed in an environment of temperature 23°C and humidity 50% RH (N / N) for one day and night. Then, the amount of toner (M / A) supplied to the developing roller during all-black printing was fixed to the value described in the following Table 1 (0.25 to 0.32 mg / cm 2 ) and continuously printed at 5% image density. The 10th copy paper was printed in full black (100% image density), and the image density (ID) and saturation (C) were measured using a Macbeth reflective image density measuring machine. * The image density (ID) is preferably above 1.00, and the saturation (C * ) is preferably 66.0 or more.

[0197] 4-3. Minimum fixing temperature of toner

[0198] A printer modified to be able to change the temperature of the fixing roller part of a commercially available non-magnetic single-component developing printer (24-sheet printer: printing speed = 24 sheets / minute) was used to change the temperature of the fixing roller, measure the fixing rate at each temperature, and find the temperature-fixing rate relationship. The lowest temperature that can obtain a fixing rate of more than 80% was defined as the minimum fixing temperature.

[0199] The fixing rate is calculated based on the image density ratio of the black-painted area in the test paper printed by the printer before and after the friction test operation. That is, when the image density before the friction test is set to ID (front) and the image density after the friction test is set to ID (back), the fixing rate (%) = [ID (back) / ID (front)] × 100. Here, the black-painted area refers to an area controlled in such a way that the developer adheres to all points (imaginary points that control the printer control unit) inside the area. The friction test operation refers to a series of operations in which the measurement part of the test paper is attached to the firmness tester with a tape, a load of 500g is applied, and a friction terminal wrapped with cotton cloth is used to rub back and forth 5 times.

[0200] 4-4. Fog measurement under normal temperature and humidity (N / N) environment

[0201] A commercially available non-magnetic one-component developing printer was left standing for one day and night in a normal temperature and normal humidity (N / N) environment of 23° C. and 50% RH, and then the fog was measured.

[0202] The fog measurement method is as follows. First, measure the hue of paper that has not been used for printing, and use the hue as the reference value (E0). Next, use the colorant to perform full white printing using the same printer as in the above "4-2. Image density and saturation measurement", and measure the hue (E1 to E6) of any 6 locations of the white coating. Calculate the difference (ΔE) between the hue (E1 to E6) and the reference value (E0), respectively, and take the largest ΔE as the fog value of the colorant, and evaluate as follows. The smaller the fog value, the less fog there is, and the better the printing. In addition, the hue is measured using a spectrophotometer (manufactured by X-Rite Inc., trade name: SpectroEye).

[0203] A: ΔE is less than 0.5

[0204] B: ΔE is 0.5 or more and less than 1.5

[0205] F: ΔE is 1.5 or more

[0206] 4-5. Storage evaluation

[0207] 10 g of toner was placed in a 100 mL polyethylene container and sealed. The container was immersed in a constant temperature water bath set to a specified temperature and taken out after 8 hours. The toner was transferred from the taken out container onto a 42 mesh sieve in a manner that minimized vibration and placed on a powder tester (manufactured by Hosokawa Micro Group, trade name: Powdertester PT-R). The amplitude of the sieve was set to 1.0 mm, and after the sieve was vibrated for 30 seconds, the mass of the toner remaining on the sieve was measured and taken as the mass of the condensed toner.

[0208] The maximum temperature at which the mass of the aggregated toner becomes 0.5 g or less is defined as the heat-resistant temperature.

[0209] 4-6. Durability test

[0210] The toner was placed in a commercial printer and left to stand for a day and night under an N / N environment, and then continuous printing was performed at a printing density of 1%, and the printing density and fog were measured every 1000 sheets. The printing density of the paper printed with full black was measured using a Macbeth reflective densitometer.

[0211] The fog is measured as follows. Perform full white printing, stop the printer midway, and allow the toner in the non-image area on the developed photoreceptor to adhere to the tape. Stick the tape on new printing paper, and measure the hue in the same manner as in the above "4-4. Fog measurement under normal temperature and humidity (N / N) environment". Stick an unused tape on the printing paper as a reference sample, and measure the hue in the same manner. The fog value is obtained by calculating the color difference ΔE between the hue of the measured sample and the reference sample.

[0212] The durability test was conducted until 15,000 sheets were continuously printed to maintain the following image quality: the fog value when printing all white was 3 or less. In the test results, >15,000 (sheets) means that the above criteria are met even if 15,000 sheets are continuously printed.

[0213] 4-7. Air-blowing charge

[0214] Under a normal temperature and humidity (N / N) environment of 23°C and 50%RH, 9.5g of a carrier (manufactured by Powdertech., trade name: EF80B2, Mn-Mg-Sr soft ferrite, average particle size of 80μm, particle size distribution of 50 to 100μm) and 0.5g of a toner were weighed and placed in a 30mL glass container, which was rotated at 150 rpm for 30 minutes to frictionally charge the toner. A nitrogen gas was charged at 1kg / cm 2 The obtained carrier and toner particles were blown with air at a pressure of , and the air-charge amount of the toner was measured.

[0215] The measurement and evaluation results of the magenta toners of Examples 1 to 7 and Comparative Examples 1 to 7 are shown in Table 1 together with the compositions of the toners.

[0216] In Table 1 below, "PR48:3" indicates CI Pigment Red 48:3, "PR57:1" indicates CI Pigment Red 57:1, "PR122" indicates CI Pigment Red 122, "PV19" indicates CI Pigment Violet 19, "SV59" indicates CI Solvent Violet 59, and "PR146" indicates CI Pigment Red 146. In Table 1 below, "surface treatment (parts)" means the content (parts) of the rosin acid metal salt relative to 100 parts of the surface-treated magenta pigment A.

[0217] [Table 1]

[0218]

[0219] In the above Table 1, the asterisk (*) in the evaluation results of Comparative Examples 1 and 2 means that since the suspension polymerization reaction did not occur, colored resin particles could not be obtained and the toner evaluation was not performed. In addition, in the above Table 1, the asterisk (*) in the evaluation results of Comparative Examples 3 and 4 means that the asterisk (*) in the evaluation results of Comparative Examples 1 and 2 means that since the suspension polymerization reaction did not occur, colored resin particles could not be obtained and the toner evaluation was not performed. This means that since the amount of coarse particles was too large, toner evaluation other than the evaluation of the coarse powder amount was not performed.

[0220] 5. Summary of toner evaluation

[0221] The magenta toner of Comparative Example 1 is a toner using CI Pigment Red 48:3 and CI Pigment Red 122 which have not been surface treated. In Comparative Example 1, since the suspension polymerization reaction did not occur, no colored resin particles were obtained. Therefore, it is known that when CI Pigment Red 48:3 which has not been surface treated is used, it becomes difficult to produce colored resin particles.

[0222] The magenta toner of Comparative Example 2 is a toner using a combination of magenta pigment X (CI Pigment Red 57:1 after surface treatment) and CI Pigment Red 122. In Comparative Example 2, since the suspension polymerization reaction did not occur, no colored resin particles were obtained. Therefore, it is known that when CI Pigment Red 57:1 after surface treatment is used, it becomes difficult to produce colored resin particles.

[0223] The magenta toner of Comparative Example 3 is a toner that uses a magenta pigment Y (CI Pigment Red 48:3 after surface treatment and the surface treatment amount is 10.0 parts) and CI Pigment Red 122. In Comparative Example 3, the amount of coarse particles is too large, 10.5%. Therefore, it is known that even if it is CI Pigment Red 48:3 after surface treatment, coarse particles are generated when the surface treatment amount is 10.0 parts or more.

[0224] The magenta toner of Comparative Example 4 is a toner using 6.0 parts of magenta pigment A1 with respect to 100 parts of the binder resin. The amount of coarse particles is as high as 12.3% in Comparative Example 4. Therefore, it is known that even if the magenta pigment A1 is added in an amount of 6.0 parts by mass or more, coarse particles are generated.

[0225] The magenta toner of Comparative Example 5 is a toner that uses only the mixed crystal of CI Pigment Red 122 and CI Pigment Violet 19 as a magenta colorant. The minimum fixing temperature of Comparative Example 5 is as high as 150°C, the fog evaluation under the N / N environment is B, the result of the durability test is as few as 8,000 sheets, and the air blowing charge is as low as 64.4μC / g. The minimum fixing temperature of Comparative Example 5 is the highest among the toners evaluated this time. In addition, the fog evaluation under the N / N environment of Comparative Example 5 is the lowest among the toners evaluated this time. In addition, the result of the durability test of Comparative Example 5 is the least among the toners evaluated this time. Furthermore, the air blowing charge of Comparative Example 5 is the smallest in the toner evaluation this time. Therefore, it can be seen that when only the above-mentioned mixed crystal is used, fog is easily generated due to insufficient charge of the toner, and thus the printing durability and low-temperature fixing property are poor.

[0226] The magenta toners of Comparative Examples 6 and 7 are toners in which CI Solvent Violet 59 and CI Pigment Red 146 are used in combination as magenta colorants. *) is as low as 60.3 or less, and the heat resistance temperature is as low as 54°C or less. Therefore, it can be seen that when CI Solvent Violet 59 and CI Pigment Red 146 are used in combination, the saturation (C * ) is low and the preservation is poor.

[0227] In addition, comparing Comparative Example 6 with Comparative Example 7, in Comparative Example 7 containing 1.0 part more of CI Pigment Red 146, the saturation (C * ) is further reduced to 58.5, and the heat resistance temperature is further reduced to 53°C. Therefore, it can be seen that in the combination of CI Solvent Violet 59 and CI Pigment Red 146, the higher the proportion of CI Pigment Red 146, the higher the saturation (C * ) is lower, the worse the preservation quality is.

[0228] On the other hand, the magenta colorant of Examples 1 to 7 contains magenta pigment A as magenta pigment A1, magenta pigment A2 or magenta pigment A3 (all of which are surface-treated and the amount of the above-mentioned surface treatment is 5.0 parts of CI Pigment Red 48:3), and the content of the magenta pigment A is 3.0 to 4.8 parts relative to 100 parts of the binding resin.

[0229] The toners of Examples 1 to 7 were controlled to have a coarse powder content of 0.9% or less, and even when CI Pigment Red 48:3 was used, the coarse particles were few and the toner particles had a desired particle size. In addition, even when the toners of Examples 1 to 7 had a supplied toner amount (M / A amount) as small as 0.25 to 0.32 mg / cm 2 In the case of any image density is also above 1.01, saturation (C * ) are all as high as 64.8 or more. In addition, the minimum fixing temperature of the toners of Examples 1 to 7 is below 145°C, and the heat resistance temperature is above 55°C, and the low-temperature fixing property and storage property are excellent. Furthermore, the blowing charge of the toners of Examples 1 to 7 is as high as 70.1μC / g or more. Since the charging property is fully exerted, the fog evaluation under the N / N environment is also high. Since the result of the durability test is more than 13,000 sheets, it has excellent printing durability.

[0230] Among them, the magenta toners of Examples 5 and 6 used a low acid value magenta pigment A having an acid value of 0.66 to 0.69 mgKOH / g, so the coarse content was significantly reduced to less than 0.2%. Even when CI Pigment Red 48:3 was used, coarse particles were extremely small.

[0231] Therefore, in the magenta toners of Examples 1 to 7, a magenta pigment A obtained by surface-treating the pigment represented by the formula (1) with a rosin acid metal salt is contained as a magenta colorant, and the content of the magenta pigment A is 1 to 5 parts by mass relative to 100 parts by mass of the binder resin, and 100 parts by mass of the magenta pigment A contains 1 to 7 parts by mass of the rosin acid metal salt. The magenta toner has a small number of coarse particles, and therefore exhibits a brighter color than before even with a small amount of toner, has a high reflection density, and has an excellent balance between low-temperature fixability and heat-resistant storage properties, thereby having excellent printing durability.

Claims

1. A magenta toner, characterized in that: Contains a binder resin and a magenta colorant, The magenta colorant is formed only of a magenta pigment A obtained by surface-treating a pigment represented by the following formula (1) with a rosin acid metal salt, or is formed only of the magenta pigment A and another magenta pigment different from the magenta pigment A, wherein the other magenta pigment is at least one selected from CI Pigment Violet 19 and CI Pigment Red 122, When the magenta colorant is formed only of the magenta pigment A and the other magenta pigments, the ratio of the magenta pigment A to the other magenta pigments is 60:40 to 40:60 in terms of mass ratio. The content of the magenta pigment A is 1 to 5 parts by mass relative to 100 parts by mass of the binder resin. 100 parts by mass of the magenta pigment A contains 1 to 7 parts by mass of the rosin acid metal salt, The acid value of the magenta pigment A is less than 2.4 mgKOH / g, In the formula (1), Me represents a divalent metal.

2. The magenta toner according to claim 1, wherein The magenta colorant is formed only of the magenta pigment A and the other magenta pigment, and the magenta toner contains CI Pigment Violet 19 as the other magenta pigment.

3. The magenta toner according to claim 1, wherein The magenta colorant is formed only of the magenta pigment A and the other magenta pigment, and the magenta toner contains CI Pigment Red 122 as the other magenta pigment.

4. The magenta toner according to claim 2, wherein The magenta toner further contains CI Pigment Red 122 as the other magenta pigment.

5. A method for producing a magenta toner, comprising the following steps: A step of preparing a polymerizable monomer composition comprising a polymerizable monomer and the magenta colorant; The step of dispersing the polymerizable monomer composition in an aqueous medium containing a dispersion stabilizer; and A step of subjecting the polymerizable monomer composition to a polymerization reaction in the presence of a polymerization initiator to form colored resin particles.

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