JP5835054B2 - Method for producing color toner for developing electrostatic image - Google Patents

Description

  The present invention is an electrostatic image developing color toner (hereinafter simply referred to as “color toner”) used for developing an electrostatic latent image in electrophotography, electrostatic recording method, electrostatic printing method and the like. )).

In general, toner production methods are roughly classified into a pulverization method and a polymerization method.
In the pulverization method, the colored resin particles are produced by pulverizing and classifying the solids of the colored resin obtained by melt-kneading the binder resin and the colorant.
Examples of the polymerization method include a suspension polymerization method in which droplets of a polymerizable monomer composition containing a polymerizable monomer and a colorant are formed, and the droplets are polymerized to produce colored resin particles. Examples include emulsion polymerization aggregation method in which an emulsified polymerizable monomer is polymerized to obtain a dispersion of resin fine particles and agglomerate with a dispersion of a colorant separately prepared to produce colored resin particles. The colored resin particles obtained by the pulverization method are indefinite, whereas the colored resin particles obtained by the polymerization method are nearly spherical and have a small particle size and a sharp particle size distribution. In particular, from the viewpoint of improving image quality characteristics such as image reproducibility and fineness, a toner whose shape and particle size distribution are highly controlled is used, such as a toner obtained by a polymerization method (so-called polymerization method toner). It has become.

  In recent years, in electrophotographic systems, colorization has been rapidly progressing, and high-quality color toners that can be used for color image forming apparatuses have been demanded. A color image forming apparatus generally includes a plurality of image forming units, and toner images having different colors are formed by the respective image forming units. Specifically, a color image is formed by sequentially transferring color toner images of, for example, yellow, magenta, cyan, and black on the same recording medium, and then fixing them by each image forming unit. The

  As described above, in the color image forming apparatus, since color images are formed by overlapping the color toners of the respective colors, the color toner is required to have excellent transparency. Color toners are also required to have excellent spectral reflection characteristics in order to improve color reproducibility. In addition, color toners are required to be capable of low-temperature fixing, to be able to precisely control positive or negative charging, and to be simple in manufacturing method.

  In order to satisfy the above characteristics, first of all, it is necessary to disperse the colorant in the binder resin as uniformly as possible. Therefore, in the case of a polymerized toner, it is necessary to carry out the polymerization after sufficiently dispersing the colorant in the polymerizable monomer composition. As the colorant, generally, a pigment that is substantially insoluble in a liquid polymerizable monomer is used. As such a colorant, a granular material is generally used, but usually it is difficult to disperse uniformly in the polymerizable monomer composition in addition to being not sufficiently fined. It is.

  Insufficient dispersion of the colorant in the polymerizable monomer composition makes it difficult to form uniform droplets of the polymerizable monomer composition in the aqueous medium, and the particle size distribution of the polymerized toner. Becomes broad, and the image density of the obtained polymerized toner tends to decrease.

  As a method for dispersing the colorant in the polymerizable monomer composition, methods using various media type dispersers have been proposed. For example, Patent Document 1 proposes a method for producing a polymerized toner for developing an electrostatic charge image using a media-type disperser in a dispersion step in which a colorant is dispersed in a monomer system containing at least a polymerizable monomer. (Claim 1). However, even when a media type disperser is used, there is no particular problem when dispersing the colorant in the polymerizable monomer composition, but in an aqueous medium containing a dispersion stabilizer. When the droplets are formed using the polymerizable monomer composition in which the colorant is dispersed, there is a problem that the dispersed colorant reaggregates.

  Patent Document 2 discloses a method for producing a polymerized toner using a media type disperser different from that described in Patent Document 1 and using a basic polymer compound as a colorant (pigment) dispersant. (Claims 1 and 5). However, even when a media type dispersing machine and a basic polymer compound dispersant are combined, there is a problem in that the dispersed colorant reaggregates depending on the type of the colorant used in combination.

  Patent Document 3 discloses a toner and a toner using a metal phthalocyanine in which a central metal can take a pentadentate or hexadentate coordination structure, and an n-electron donating compound capable of coordinating with the central metal of the metal phthalocyanine. A production method is disclosed, and a styrene- (4-vinylpyridine) random copolymer is disclosed as the n-electron-donating compound (Claim 1, Claim 9, Claim 17, and Specification). Paragraphs [0075]-[0078]). Patent Document 4 discloses a step of emulsifying or dispersing a toner material liquid containing a material constituting the toner in an aqueous medium so that the volume mode particle size of the toner material liquid is 0.05 to 2 μm. The toner for developing an electrostatic charge image obtained through the above process is disclosed, and it is also disclosed that the toner material liquid contains a modified polyurethane dispersant as a polymer dispersant (claims 1 and 10). However, as a result of the study by the present inventors, even when a styrene- (4-vinylpyridine) random copolymer or a modified polyurethane-based dispersant is used, the dispersed colorant may be reused depending on the type of the colorant used in combination. It was difficult to solve the problem of aggregation.

JP-A-6-75429 Japanese Patent Laying-Open No. 2005-77729 JP 2003-277463 A JP 2006-293309 A

  An object of the present invention is to provide a polymerizable monomer composition in which, when a colorant (pigment) having a specific structure is used, the colorant (pigment) does not aggregate in the polymerizable monomer and the colorant is dispersed. Even if suspension polymerization is carried out after forming the product in droplets in an aqueous dispersion medium, the resulting colored resin particles are less likely to have a large particle size, and when printing is performed using the obtained toner, the print density is high. Another object of the present invention is to provide a method for producing a toner having high image saturation.

The present inventor diligently studied whether aggregation of colored resin particles dispersed in the polymerizable monomer composition can be suppressed when a toner is produced by suspension polymerization. Aggregation of the colored resin particles is caused by a decrease in dispersion stability in the droplets of the polymerizable monomer composition. The drop in dispersion stability of the polymerizable monomer composition droplets may be caused by, for example, using a dispersant that adversely affects the re-aggregation of the colorant or a dispersion stabilizer such as magnesium hydroxide colloid, It is caused by using a highly polar colorant that elutes when exposed to an aqueous dispersion. As a result of intensive studies, the present inventor solved the above problem by incorporating a dispersant having a specific structure in the polymerizable monomer when dispersing the colorant (pigment) in the polymerizable monomer. I found out that I can do it.
That is, according to the present invention, a polymerizable monomer composition containing at least a polymerizable monomer and a colorant is suspended in an aqueous dispersion to form droplets of the polymerizable monomer composition. A method for producing a color toner for developing an electrostatic charge image, comprising: a suspension step of obtaining a suspension in which the dispersion is dispersed; and a step of subjecting the suspension to suspension polymerization in the presence of a polymerization initiator to obtain colored resin particles. In the suspending step, at least one of a quinacridone pigment and a benzimidazolone pigment is used as a colorant, and as a dispersant for dispersing the colorant in the polymerizable monomer composition, There is provided a method for producing a color toner for developing an electrostatic image, characterized by using a block copolymer having a monomer unit block.

  In this invention, it is preferable that content of the vinylpyridine monomer unit block in the said block copolymer is 0.5-20 mol%.

  In the present invention, it is preferable that the block copolymer further has a (meth) acrylic acid ester monomer unit block.

  In the present invention, it is preferable that the block copolymer further has an alkylene oxide monomer unit block.

  In this invention, it is preferable to add 0.2-4 mass parts of said block copolymers with respect to 100 mass parts of polymerizable monomers in the said suspension process.

  According to the method for producing a color toner for developing an electrostatic image of the present invention as described above, a colored resin is obtained by using a block copolymer having a vinylpyridine monomer unit block as a dispersant for a specific colorant. Provided is a color toner that suppresses particle aggregation, has a narrow particle size distribution, and has a print density and image saturation superior to those of the prior art.

  In the method for producing a color toner for developing an electrostatic image of the present invention, a polymerizable monomer composition containing at least a polymerizable monomer and a colorant is suspended in an aqueous dispersion to obtain a polymerizable monomer. Electrostatic charge image development including a suspension step for obtaining a suspension in which droplets of a monomer composition are dispersed, and a step of subjecting the suspension to suspension polymerization in the presence of a polymerization initiator to obtain colored resin particles A method for producing a color toner, wherein in the suspension step, at least one of a quinacridone pigment and a benzimidazolone pigment is used as a colorant, and the colorant is dispersed in the polymerizable monomer composition. A block copolymer having a vinylpyridine monomer unit block is used as a dispersant.

Hereinafter, an electrostatic image developing color toner (hereinafter, simply referred to as “color toner”) manufactured by the manufacturing method of the present invention will be described.
The color toner obtained by the present invention contains at least a binder resin, a colorant, and a specific block copolymer.
Hereinafter, the manufacturing method of the colored resin particles used in the present invention, the colored resin particles obtained by the manufacturing method, the manufacturing method of the color toner of the present invention using the colored resin particles, and the color toner obtained by the manufacturing method, These will be described in order.

1. Method for Producing Colored Resin Particles Colored resin particles used in the present invention are produced by the following process using a suspension polymerization method.

1-1. Preparation Step of Polymerizable Monomer Composition First, the polymerizable monomer, the colorant, and the specific block copolymer, and other additives such as a charge control agent added as necessary are mixed, A polymerizable monomer composition is prepared. For mixing at the time of preparing the polymerizable monomer composition, for example, a media type disperser, an inline type emulsifying disperser, or the like can be used, and an inline type emulsifying disperser is preferably used.

  In the present invention, the polymerizable monomer means a monomer having a polymerizable functional group, and the polymerizable monomer is polymerized to become a binder resin. It is preferable to use a monovinyl monomer as the main component of the polymerizable monomer. Examples of the monovinyl monomer include styrene; styrene derivatives such as vinyl toluene and α-methylstyrene; acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid 2 Acrylic esters such as ethylhexyl and dimethylaminoethyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and dimethylaminoethyl methacrylate; acrylonitrile And nitrile compounds such as methacrylonitrile; amide compounds such as acrylamide and methacrylamide; olefins such as ethylene, propylene, and butylene. These monovinyl monomers can be used alone or in combination of two or more. Of these, styrene, styrene derivatives, and acrylic esters or methacrylic esters are preferably used as monovinyl monomers.

In order to improve hot offset and storage stability, it is preferable to use any crosslinkable polymerizable monomer together with the monovinyl monomer. A crosslinkable polymerizable monomer means a monomer having two or more polymerizable functional groups. Examples of the crosslinkable polymerizable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; alcohols having two or more hydroxyl groups such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; Ester compounds in which two or more carboxylic acids having a carbon-carbon double bond are ester-bonded; other divinyl compounds such as N, N-divinylaniline and divinyl ether; compounds having three or more vinyl groups; Can be mentioned. These crosslinkable polymerizable monomers can be used alone or in combination of two or more.
In the present invention, the crosslinkable polymerizable monomer is usually used at a ratio of 0.1 to 5 parts by mass, preferably 0.3 to 2 parts by mass with respect to 100 parts by mass of the monovinyl monomer. desirable.

  Furthermore, it is preferable to use a macromonomer as a part of the polymerizable monomer because the balance between the storage stability of the obtained toner and the fixing property at low temperature is improved. The macromonomer has a polymerizable carbon-carbon unsaturated double bond at the end of the molecular chain, and is a reactive oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000. The macromonomer is preferably one that gives a polymer having a higher Tg than the glass transition temperature of the polymer obtained by polymerizing the monovinyl monomer (hereinafter sometimes referred to as “Tg”). The macromonomer is preferably used in an amount of 0.03 to 5 parts by mass, more preferably 0.05 to 1 part by mass, with respect to 100 parts by mass of the monovinyl monomer.

In the present invention, at least one of a quinacridone pigment and a benzimidazolone pigment is used as a colorant.
The quinacridone pigment used in the present invention is not particularly limited. I. Dimethylquinacridone pigments such as CI Pigment Red 122; I. Pigment red 202, C.I. I. Dichloroquinacridone pigments such as CI Pigment Red 209; I. Examples thereof include unsubstituted quinacridone pigments such as CI Pigment Violet 19. Among these pigments, C.I. I. Pigment Red 122 is preferable.
The benzimidazolone pigment used in the present invention is not particularly limited. I. Pigment brown 25, C.I. I. Pigment violet 32, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 167, C.I. I. Pigment yellow 175, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 181, C.I. I. Pigment yellow 194, C.I. I. Pigment orange 36, C.I. I. Pigment orange 60, C.I. I. Pigment orange 62, C.I. I. Pigment orange 72, and C.I. I. Pigment Red 185 and the like can be exemplified. Among these pigments, C.I. I. Pigment Yellow 180 is preferable.

  In the present invention, each colorant can be used alone or in combination of two or more. The amount of the colorant is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the monovinyl monomer.

The block copolymer used in the present invention has at least a vinylpyridine monomer unit block. The “vinylpyridine monomer unit” in the present invention includes a 4-vinylpyridine monomer unit, a 2-vinylpyridine monomer unit, and a 3-vinylpyridine monomer unit. The “vinylpyridine monomer unit block” in the present invention is any one of 4-vinylpyridine monomer unit, 2-vinylpyridine monomer unit, and 3-vinylpyridine monomer unit. May be composed of any two of them, or may include any of these monomer units.
Examples of the monomer constituting the vinylpyridine monomer unit block include 4-vinylpyridine, 4-vinylpyridinium ion, 2-vinylpyridine, 2-vinylpyridinium ion, 3-vinylpyridine, 3-vinylpyridinium ion, and the like. Among them, 4-vinylpyridine is preferable.
The pyridine skeleton in the vinylpyridine monomer may have a substituent. As a substituent, a C1-C10 hydrocarbon group etc. are mentioned, for example.

The content of the vinylpyridine monomer unit block in the block copolymer is preferably 0.5 to 20 mol%. When the content is less than 0.5 mol%, there is a possibility that the effect of suppressing the aggregation of the colored resin particles, which is the effect of the present invention, and the effect of improving the printing density and saturation may not be sufficiently obtained. . On the other hand, when the content exceeds 20 mol%, the solubility of the block copolymer in the polymerizable monomer may be lowered.
As for content of the vinylpyridine monomer unit block in a block copolymer, it is more preferable that it is 1-7 mol%, and it is further more preferable that it is 2-4 mol%.
In addition, the said content is a value when the number average molecular weight of a block copolymer is 100 mol%.
The number average molecular weight of the vinylpyridine monomer unit block is preferably 500 to 2,000, and more preferably 800 to 1,500.

The block copolymer preferably further has a (meth) acrylic acid ester monomer unit block. In the present invention, “(meth) acrylic acid ester” is a concept including both acrylic acid ester and methacrylic acid ester. As a monomer which comprises a (meth) acrylic acid ester monomer unit block, the compound etc. which are represented by following formula (I) are mentioned, for example.
CH ₂ ═C (R _a ) — (C═O) —O—R _b Formula (I)
(In the above formula (I), -R _a is hydrogen or a methyl group. In the above formula (I), -R _b has no substituent and has 1 to 18 carbon atoms, and It is one group selected from the group consisting of an alkyl group having a substituent and having 1 to 18 carbon atoms.)

  As a (meth) acrylic acid ester monomer unit block, for example, when a butyl acrylate monomer unit block is included, the content of the butyl acrylate monomer unit block in the block copolymer is 5 to 5. It is preferably 49.5 mol%, more preferably 8 to 30 mol%, and even more preferably 10 to 23 mol%. The butyl acrylate monomer unit block preferably has a number average molecular weight of 6,000 to 12,000, and more preferably 8,000 to 10,000.

The block copolymer preferably further has an alkylene oxide monomer unit block. The alkylene oxide monomer unit block may constitute the main chain of the block copolymer or may constitute the side chain (graft chain) of the block copolymer. Those constituting the side chain of the copolymer are preferred. Examples of the molecular structure that becomes the side chain of the block copolymer include a structure in which the alkylene oxide monomer unit block is transesterified with the ester moiety in the above-described (meth) acrylate monomer unit block. .
The alkylene oxide monomer unit block is a polymer obtained by ring-opening polymerization of at least one of ethylene oxide and propylene oxide. Since it has excellent affinity for pigments, it undergoes ring-opening polymerization of ethylene oxide. The resulting polymer is preferred. In the polymer obtained by ring-opening polymerization of ethylene oxide or propylene oxide, it is preferable that one of hydrogen at two polymer ends is substituted with an alkyl group having 1 to 6 carbon atoms, and a methyl group or an ethyl group is more preferable. Preferably, a methyl group is more preferable.
As an alkylene oxide monomer unit block, for example, when a methoxypolyethylene oxide block is included, the content of the methoxypolyethylene oxide block in the block copolymer is preferably 50 to 94.5 mol%, 70 to More preferably, it is 94 mol%, and it is further more preferable that it is 75-88 mol%. The methoxypolyethylene oxide block preferably has a number average molecular weight of 100 to 1,000, and more preferably 300 to 800.

  Other examples of monomers constituting the block copolymer include ethylene, propylene, n-butylene, i-butylene, styrene, substituted styrene, conjugated diene, acrolein, vinyl acetate, vinyl pyrrolidone, vinyl imidazole, and maleic anhydride. Acids, (alkyl) acrylic anhydrides, (alkyl) acrylates, (alkyl) acrylic esters other than the (meth) acrylic esters, (alkyl) acrylonitriles, (alkyl) acrylamides, vinyl halides, and vinylidene halogens And the like.

  The number average molecular weight of the block copolymer is preferably 10,000 to 30,000, more preferably 15,000 to 25,000, and further preferably 18,000 to 23,000. .

In suspension polymerization, it is preferable to add 0.2 to 4 parts by mass of a block copolymer to 100 parts by mass of the polymerizable monomer. If the amount added is less than 0.2 parts by mass, the effect of suppressing aggregation of toner particles, which is the effect of the present invention, and the effect of improving the printing density and saturation may not be sufficiently obtained. . If the amount added exceeds 4 parts by mass, the particle size distribution of the toner particles may become wider (broader) than before.
As for the addition amount of the block copolymer with respect to 100 mass parts of polymerizable monomers, it is more preferable that it is 0.5-3 mass parts.

Hereafter, the typical example of the manufacturing method of a block copolymer is demonstrated. The following typical example is merely an example of a method for producing a block copolymer, and the block copolymer used in the present invention is not necessarily limited to that produced according to this typical example.
First, a polymer which becomes a counterpart of copolymerization such as polyvinylpyridine (raw material of vinylpyridine monomer unit block) or poly (meth) acrylic acid ester (raw material of (meth) acrylic acid ester unit block) One of these is synthesized. The amount of monomer required is calculated in advance from the content of each monomer unit block described above. From the viewpoint of synthesizing the block copolymer, the polymerization conversion rate in this synthesis stage is preferably 50% or less.
For the polymerization, a polymerization initiator, a solvent such as 1-methoxy-2-propyl acetate, and the like are used in addition to the monomers described above as raw materials.
From the viewpoint of synthesizing the block copolymer, a living polymerization method in which a reaction point is present at the end of the polymer is used as the polymerization method.

As the polymerization initiator, it is particularly preferable to use a nitroxyl ether or a nitroxyl radical from the viewpoint that the living polymerization proceeds efficiently.
As the nitroxyl ether, for example, compounds represented by the following formulas (a-1) to (a-7) can be used.

  As the nitroxyl radical, for example, radicals represented by the following formulas (b-1) to (b-7) can be used.

Among the polymerization initiators described above, it is preferable to use at least one of the nitroxyl ether represented by the above formula (a-1) and the nitroxyl radical represented by the above formula (b-1). .
The addition amount of the polymerization initiator is preferably 0.01 to 30 mol%, more preferably 0.1 to 20 mol%, when the raw material mixture such as the monomer is 100 mol%, and more preferably 0 to 20 mol%. More preferably, it is 1-10 mol%.

  Next, a block copolymer is synthesized. When polyvinyl pyridine is first synthesized, monomers such as polyvinyl pyridine and (meth) acrylic acid ester are mixed and polymerized. When another polymer such as poly (meth) acrylic acid ester is synthesized first, the other polymer and vinylpyridine are mixed and polymerized.

  The block copolymer may be composed of the above-mentioned two types of monomer unit blocks, but may also contain three or more types of monomer unit blocks. For example, an alkylene oxide monomer unit block may be further introduced by transesterification with respect to a copolymer containing a vinylpyridine monomer unit block and a (meth) acrylic acid ester monomer unit block. The transesterification can be performed by a known method.

  From the viewpoint of improving the releasability of the toner from the fixing roll during fixing, it is preferable to add a release agent to the polymerizable monomer composition. Any releasing agent can be used without particular limitation as long as it is generally used as a releasing agent for toner.

The release agent preferably contains at least one of ester wax and hydrocarbon wax. By using these waxes as a release agent, the balance between low-temperature fixability and storage stability can be made suitable.
The ester wax suitably used as the release agent in the present invention is more preferably a polyfunctional ester wax, such as pentaerythritol ester such as pentaerythritol tetrapalinate, pentaerythritol tetrabehenate, pentaerythritol tetrastearate, etc. Compound: hexaglycerin tetrabehenate tetrapalinate, hexaglycerin octabehenate, pentaglycerin heptabehenate, tetraglycerin hexabehenate, triglycerin pentabehenate, diglycerin tetrabehenate, glycerin tribe Glycerin ester compounds such as henate; Dipentaerythritol ester compounds such as dipentaerythritol hexamyristate and dipentaerythritol hexapalmitate; Of these, glycerin ester compounds are preferred, hexaglycerin tetrabehenate tetrapalinate, hexaglycerin octabehenate, tetraglycerin hexabehenate, and triglycerin pentabehenate are more preferred. Nate is particularly preferred.

Examples of the hydrocarbon wax suitably used as a release agent in the present invention include polyethylene wax, polypropylene wax, Fischer-Tropsch wax, petroleum-based wax, etc. Among them, Fischer-Tropsch wax and petroleum-based wax are preferable, and petroleum-based wax. Is more preferable.
The number average molecular weight of the hydrocarbon wax is preferably 300 to 800, more preferably 400 to 600. Moreover, the penetration of the hydrocarbon wax measured by JIS K2235 5.4 is preferably 1 to 10, and more preferably 2 to 7.

In addition to the mold release agent, for example, natural wax such as jojoba; mineral wax such as ozokerite;
The mold release agent may be used in combination with one or more waxes as described above.
The release agent is preferably used in an amount of 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the monovinyl monomer.

As other additives, a positively or negatively chargeable charge control agent can be used to improve the chargeability of the toner.
The charge control agent is not particularly limited as long as it is generally used as a charge control agent for toner, but among charge control agents, the compatibility with the polymerizable monomer is high, and stable chargeability. (Charge stability) can be imparted to the toner particles, and therefore a positively or negatively chargeable charge control resin is preferred. Further, from the viewpoint of obtaining a positively chargeable toner, a positively chargeable charge control resin is preferred. More preferably used.
Examples of positively chargeable charge control agents include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds and imidazole compounds, polyamine resins as charge control resins that are preferably used, and quaternary ammonium group-containing copolymers. , And quaternary ammonium base-containing copolymers.
Negatively chargeable charge control agents include azo dyes containing metals such as Cr, Co, Al, and Fe, salicylic acid metal compounds and alkylsalicylic acid metal compounds, and sulfonic acid group containing charge control resins that are preferably used Examples thereof include a copolymer, a sulfonate group-containing copolymer, a carboxylic acid group-containing copolymer, and a carboxylic acid group-containing copolymer.
In the present invention, the charge control agent is usually used in a proportion of 0.01 to 10 parts by mass, preferably 0.03 to 8 parts by mass, with respect to 100 parts by mass of the monovinyl monomer. If the addition amount of the charge control agent is less than 0.01 parts by mass, fog may occur. On the other hand, when the addition amount of the charge control agent exceeds 10 parts by mass, printing stains may occur.

As other additives, it is preferable to use a molecular weight modifier when polymerizing a polymerizable monomer that is polymerized to become a binder resin.
The molecular weight modifier is not particularly limited as long as it is generally used as a molecular weight modifier for toner. For example, t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2, Mercaptans such as 4,6,6-pentamethylheptane-4-thiol; tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N, N′-dimethyl-N, N′-diphenylthiuram disulfide, N, And thiuram disulfides such as N′-dioctadecyl-N, N′-diisopropylthiuram disulfide; These molecular weight modifiers may be used alone or in combination of two or more.
In this invention, it is desirable to use a molecular weight modifier in the ratio of 0.01-10 mass parts normally with respect to 100 mass parts of monovinyl monomers, Preferably it is 0.1-5 mass parts.

1-2. Suspension process to obtain a suspension (droplet formation process)
In the present invention, a polymerizable monomer composition containing at least a polymerizable monomer, a colorant, and the block copolymer described above is preferably dispersed in an aqueous medium containing a dispersion stabilizer, and polymerization is started. After adding the agent, droplet formation of the polymerizable monomer composition is performed. The method for forming droplets is not particularly limited. For example, an (in-line type) emulsifying disperser (trade name “Milder” manufactured by Ebara Manufacturing Co., Ltd.), a high-speed emulsifying disperser (trade name “T. K. Homomixer MARK Type II ") or the like capable of strong stirring.

  As a polymerization initiator, persulfates such as potassium persulfate and ammonium persulfate: 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-methyl-N- (2- Hydroxyethyl) propionamide), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2,4-dimethylvaleronitrile), and 2,2′-azobisisobutyronitrile Di-t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylbutanoate, diisopropylperoxydicarbonate, di- Organic peroxides such as -t-butylperoxyisophthalate and t-butylperoxyisobutyrate It is. These can be used alone or in combination of two or more. Among these, it is preferable to use an organic peroxide because residual polymerizable monomers can be reduced and printing durability is excellent.

  Among organic peroxides, peroxyesters are preferable because non-aromatic peroxyesters, that is, peroxyesters having no aromatic ring, are preferable because initiator efficiency is good and the amount of remaining polymerizable monomers can be reduced. More preferred.

  As described above, the polymerization initiator may be added before the droplet formation after the polymerizable monomer composition is dispersed in the aqueous medium. However, the polymerization initiator is not dispersed in the aqueous medium. It may be added to the monomer composition.

  The addition amount of the polymerization initiator used for the polymerization of the polymerizable monomer composition is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 100 parts by mass of the monovinyl monomer. It is -15 mass parts, Most preferably, it is 1-10 mass parts.

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

  In the present invention, the aqueous medium preferably 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; metals such as aluminum oxide and titanium oxide. Oxides; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; inorganic compounds such as; water-soluble polymers such as polyvinyl alcohol, methylcellulose, and gelatin; anionic surfactants; Organic compounds such as nonionic surfactants; amphoteric surfactants; The said dispersion stabilizer can be used 1 type or in combination of 2 or more types.

  Among the above dispersion stabilizers, inorganic compounds, particularly colloids of poorly water-soluble metal hydroxides are preferred. By using a colloid of an inorganic compound, particularly a poorly water-soluble metal hydroxide, the particle size distribution of the colored resin particles can be narrowed, and the residual amount of the dispersion stabilizer after washing can be reduced. The toner thus produced can reproduce the image clearly and has excellent environmental stability.

1-3. Polymerization Step As in 1-2 above, droplet formation is performed, the resulting aqueous dispersion is heated to initiate polymerization, and an aqueous dispersion of colored resin particles is formed.
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.

  The colored resin particles may be used as a polymerized toner by adding an external additive as it is, but the so-called core-shell type obtained by using the colored resin particles as a core layer and forming a shell layer different from the core layer on the outside thereof. It is preferable to use colored resin particles (also referred to as “capsule type”). The core-shell type colored resin particles balance the reduction of the fixing temperature and the prevention of aggregation during storage by coating the core layer made of a material having a low softening point with a material having a higher softening point. be able to.

  There is no restriction | limiting in particular as a method of manufacturing a core shell type colored resin particle using the said colored resin particle mentioned above, It can manufacture by a conventionally well-known method. An in situ polymerization method and a phase separation method are preferable from the viewpoint of production efficiency.

A method for producing core-shell type colored resin particles by in situ polymerization will be described below.
In the aqueous dispersion in which the colored resin particles are dispersed, a polymerizable monomer (shell polymerizable monomer) for forming a shell layer and a polymerization initiator are added and polymerized to form a core-shell type. Colored resin particles can be obtained.
At this time, a small particle size fine particle inhibitor may be added.

  Here, the “small particle size fine particle inhibitor” is a polymerizable unit that exists (elutes) in the aqueous dispersion medium (in the aqueous phase) in the process of forming droplets of the polymerizable monomer composition. It refers to a compound that captures at least one of a radical derived from a monomer and a radical derived from a polymerization initiator and suppresses the generation of small-sized fine particles that are by-produced during polymerization.

  Examples of the small particle size fine particle inhibitor include hydroquinone, hydroxyhydroquinone, hydroquinonesulfonic acid, hydroquinonecarboxylic acid, and metal salts thereof; caffeic acid, 3,4-dihydroxybenzoic acid, 3,4-dihydroxybenzenesulfonic acid, And metal salts thereof; pyrogallol, 2,3-dihydroxybenzoic acid, 2,3-dihydroxybenzenesulfonic acid, 2,3-dihydroxycinnamic acid, and metal salts thereof; and the like.

  As the polymerizable monomer for the shell, the same monomers as the aforementioned polymerizable monomers can be used. Among them, it is preferable to use monomers such as styrene, acrylonitrile, and methyl methacrylate, which can obtain a polymer having a Tg exceeding 80 ° C., alone or in combination of two or more.

  As a polymerization initiator used for polymerization of the polymerizable monomer for shell, persulfate metal salts such as potassium persulfate and ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) Water-soluble such as azo initiators such as) propionamide) and 2,2′-azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide); A polymerization initiator can be mentioned. 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, and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer for shell.

  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.

1-4. Washing, filtration, dehydration, and drying steps After the polymerization, the aqueous dispersion of colored resin particles is subjected to filtration, removal of the dispersion stabilizer, and operations of washing, dehydration, and drying after the completion of the polymerization. Is preferably repeated several times as necessary.

  As the above washing method, when an inorganic compound is used as the dispersion stabilizer, the dispersion stabilizer can be dissolved in water and removed by adding an acid or alkali to the aqueous dispersion of colored resin particles. preferable. When a colloid of a poorly water-soluble inorganic hydroxide is used as the dispersion stabilizer, it is preferable to adjust the pH of the colored resin particle aqueous dispersion to 6.5 or less by adding an acid. 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. Particularly, since the removal efficiency is large and the burden on the manufacturing equipment is small, Sulfuric acid is preferred.

  Various known methods and the like can be used as the method of dehydration and filtration, and there is no particular limitation. Examples thereof include a centrifugal filtration method, a vacuum filtration method, and a pressure filtration method. Also, the drying method is not particularly limited, and various methods can be used.

2. Colored resin particles Colored resin particles are obtained by the suspension polymerization method described above.
Hereinafter, the colored resin particles constituting the toner will be described. The colored resin particles described below include both core-shell type and non-core type.

  The volume average particle diameter (Dv) of the colored resin particles is preferably 4 to 12 μm, and more preferably 5 to 10 μm. When Dv is less than 4 μm, the fluidity of the polymerized toner is lowered, and transferability may be deteriorated or the image density may be lowered. When Dv exceeds 12 μm, the resolution of the image may decrease.

  The colored resin particles have a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of preferably 1.0 to 1.3, more preferably 1. 0-1.2. If Dv / Dn exceeds 1.3, transferability, image density, and resolution may decrease. The volume average particle diameter and the number average particle diameter of the colored resin particles can be measured using, for example, a particle size analyzer (trade name “Multisizer” manufactured by Beckman Coulter).

From the viewpoint of image reproducibility, the average circularity of the colored resin particles of the present invention is preferably 0.96 to 1.00, more preferably 0.97 to 1.00, and 0.98 to More preferably, it is 1.00.
When the average circularity of the colored resin particles is less than 0.96, the fine line reproducibility of printing may be deteriorated.

  In the present invention, the circularity is defined as a value obtained by dividing the circumference of a circle having the same projected area as the particle image by the circumference of the projected image of the particle. The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of the particles, and is an index indicating the degree of unevenness of the colored resin particles. The average circularity is determined by the colored resin particles. 1 is shown in the case of a perfect sphere, and the value becomes smaller as the surface shape of the colored resin particles becomes more complicated.

3. Method for Producing Color Toner of the Present Invention The colored resin particles described above can be added and added (externally added) uniformly and suitably to the surface of the colored resin particles by mixing and stirring together with the external additive. . The one-component toner may be further mixed and stirred together with carrier particles to form a two-component toner.

  The stirrer that performs the external addition treatment is not particularly limited as long as the stirrer can attach the external additive to the surface of the colored resin particles. For example, Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), FM mixer (: Trade name, manufactured by Nippon Coke Industries Co., Ltd.), super mixer (: product name, manufactured by Kawada Seisakusho Co., Ltd.), Q mixer (: product name, manufactured by Nihon Coke Industries Co., Ltd.), mechano-fusion system (: trade name, Hosokawa Micron Corporation) And a mechano mill (trade name, manufactured by Okada Seiko Co., Ltd.) and the like, and a stirrer capable of mixing and stirring can be used for external addition.

External additives include inorganic fine particles made of silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, cerium oxide, etc .; polymethyl methacrylate resin, silicone resin, melamine resin, etc. Organic fine particles; and the like. Among these, inorganic fine particles are preferable, and among inorganic fine particles, silica and titanium oxide are preferable, and fine particles made of silica are particularly preferable.
These external additives can be used alone or in combination of two or more. Two or more types of silica having different particle diameters may be used in combination.

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

  The color toner obtained by the production method of the present invention can suppress aggregation of toner particles by using a block copolymer having a vinylpyridine monomer unit block as a dispersant for a specific colorant. This color toner has a narrow distribution and a print density and high saturation superior to those of the prior art.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited only to these examples. Parts and% are based on mass unless otherwise specified.
The test methods performed in the examples and comparative examples are as follows.

1. Synthesis of block copolymer containing vinylpyridine monomer unit [Production Example 1]
(1-1) Synthesis of n-butyl polyacrylate In a round bottom flask equipped with a magnetic stirrer, a cooling device, an internal thermometer, and a dropping funnel, 150 g of n-butyl acrylate, ) 2,6-diethyl-2,3,6-trimethyl-4-oxo-1- (1-phenylethoxy) piperidine and 1-methoxy-2-propylacetate (hereinafter referred to as “MPA”) 120 g was added, and polymerization was carried out at 135 ° C. while stirring under a nitrogen atmosphere until the polymerization conversion was about 8%. Further, 330 g of n-butyl acrylate was slowly added using a dropping funnel and polymerized at 135 ° C. until the polymerization conversion reached about 48%. Residual monomer and solvent were removed at 80 ° C. and 1.2 kPa to obtain n-butyl polyacrylate. It was 8,600 when the number average molecular weight Mn of the obtained polyacrylic acid n-butyl was measured by GPC (THF, polystyrene conversion).

(1-2) Synthesis of (poly (n-butyl acrylate)-(poly-4-vinylpyridine) block copolymer) In a three-necked 500 mL round bottom flask equipped with a magnetic stirrer, a condenser, and a thermometer, Add 231.8 g of poly (n-butyl acrylate) obtained in (1-1) above, 27.8 g of 4-vinylpyridine and 80 g of MPA, deaerate three times with nitrogen, and maintain at 125 ° C. under a nitrogen atmosphere. For 8 hours. Residual monomer and solvent were distilled off at 80 ° C. and 1.2 kPa to obtain a (poly (n-butyl acrylate)-(poly-4-vinylpyridine) block copolymer. It was 9,500 when the number average molecular weight Mn of the obtained block copolymer was measured by GPC (THF, polystyrene conversion).

(1-3) Synthesis of (methoxypolyethylene oxide grafted polyacrylic acid)-(poly (n-butyl acrylate)-(poly-4-vinylpyridine) block copolymer) Distillation column using dry ice-acetone cooling, and magne In a 500 mL flask equipped with a tic stirrer, 100 g of xylene, 102.3 g of (polyacrylic acid n-butyl)-(poly-4-vinylpyridine) block copolymer obtained by the above (1-2), and the number average 135.1 g of methoxypolyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) having a molecular weight of 550 was added and dried using azeotropic distillation of xylene. Tetra (isopropyl) orthotitanate (0.36 g) was added in three portions at 190 to 205 ° C. over 3 hours. By-product n-butanol was distilled off under reduced pressure, and (methoxypolyethylene oxide grafted polyacrylic acid)-(poly (n-butyl acrylate))-(poly-4-vinylpyridine) block copolymer 1 (hereinafter, Which may be referred to as block copolymer 1). It was 22,000 when the number average molecular weight Mn of the obtained block copolymer 1 was measured by GPC (THF, polystyrene conversion).

[Production Example 2]
(2-1) Synthesis of n-butyl polyacrylate In a round bottom flask equipped with a magnetic stirrer, a cooling device, an internal thermometer, and a dropping funnel, 150 g of n-butyl acrylate, the above formula (a-1 8.6 g of 2,6-diethyl-2,3,6-trimethyl-4-oxo-1- (1-phenylethoxy) piperidine and 120 g of MPA as shown in FIG. The polymerization was carried out until the polymerization conversion was about 8%. Further, 291.1 g of n-butyl acrylate was slowly added using a dropping funnel and polymerized at 135 ° C. until the polymerization conversion reached about 48%. Residual monomer and solvent were removed at 80 ° C. and 1.2 kPa to obtain n-butyl polyacrylate. It was 7,900 when the number average molecular weight Mn of the obtained polyacrylic acid n-butyl was measured by GPC (THF, polystyrene conversion).

(2-2) Synthesis of (poly (n-butyl acrylate)-(poly-4-vinylpyridine) block copolymer) In a three-necked 500 mL round bottom flask equipped with a magnetic stirrer, a condenser, and a thermometer, Add 291.1 g of poly (n-butyl acrylate) obtained in (2-1) above, 40.9 g of 4-vinylpyridine and 80 g of MPA, deaerate three times with nitrogen, and at 125 ° C. under nitrogen atmosphere For 8 hours. Residual monomer and solvent were distilled off at 80 ° C. and 1.2 kPa to obtain a (poly (n-butyl acrylate)-(poly-4-vinylpyridine) block copolymer. It was 9,200 when the number average molecular weight Mn of the obtained block copolymer was measured by GPC (THF, polystyrene conversion).

(2-3) Synthesis of (methoxypolyethylene oxide grafted polyacrylic acid)-(poly (n-butyl acrylate)-(poly-4-vinylpyridine) block copolymer) Distillation column using dry ice-acetone cooling, and magne In a 500 mL flask equipped with a tic stirrer, 100 g of xylene, 99.4 g of a (polyacrylic acid n-butyl)-(poly-4-vinylpyridine) block copolymer obtained by the above (2-2) and a number average molecular weight Was added with 114.7 g of 550 methoxypolyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.), and dried using azeotropic distillation of xylene. Tetra (isopropyl) orthotitanate (0.36 g) was added in three portions at 190 to 205 ° C. over 3 hours. The by-produced n-butanol was distilled off under reduced pressure, and (methoxypolyethylene oxide grafted polyacrylic acid)-(poly (n-butyl acrylate))-(poly-4-vinylpyridine) block copolymer 2 (hereinafter, Which may be referred to as block copolymer 2). It was 21,500 when the number average molecular weight Mn of the obtained block copolymer 2 was measured by GPC (THF, polystyrene conversion).

2. Synthesis of styrene- (4-vinylpyridine) random copolymer [Production Example 3]
Tetrahydrofuran (THF) (300 mL) was added to a 1 L reaction vessel, and the temperature of THF was adjusted to 68 ° C. Next, a mixed solution of 95 g of styrene, 5 g of 4-vinylpyridine, 6 g of 2,2-azoisobutyronitrile, and 80 mL of THF was prepared, and the mixed solution was dropped into the reaction vessel over 2 hours. After the dropping, the mixture was refluxed at 68 ° C. for 6 hours. This was cooled to room temperature and 1 L of methanol was added. The precipitated crystals were filtered, washed with methanol and washed with water. The obtained powder was dried under reduced pressure at a temperature of 30 ° C. for 24 hours to obtain 30.8 g of a styrene- (4-vinylpyridine) random copolymer (hereinafter sometimes referred to as a random copolymer). When the obtained styrene- (4-vinylpyridine) random copolymer was subjected to IR spectrum, elemental analysis and molecular weight measurement, the copolymerization mass ratio of the styrene monomer unit to the 4-vinylpyridine monomer unit was It was found that styrene: 4-vinylpyridine = 96: 4, the number average molecular weight (Mn) was 2,850, and the weight average molecular weight (Mw) was 7,410.

3. Production of color toner for developing electrostatic image [Example 1]
80 parts of styrene and 20 parts of n-butyl acrylate as a polymerizable monomer, and C.I. which is one of benzimidazolone pigments as a yellow pigment. I. 6 parts of Pigment Yellow 180 (manufactured by Clariant, trade name “toner yellow HG”) and 12 parts of block copolymer synthesized in Production Example 1 as a dispersing agent The mixture was dispersed using a name “Ebara Milder”) to obtain a polymerizable monomer mixture.
1 part of a charge control resin (trade name “Acrybase FCA-207P” manufactured by Fujikura Kasei Co., Ltd.) as a charge control agent, 8 parts of a fatty acid ester wax as a mold release agent, and polymethacryl as a macromonomer are added to the polymerizable monomer mixture. 0.3 parts of acid ester macromonomer (trade name “AA6”, manufactured by Toagosei Co., Ltd.), 0.3 part of divinylbenzene as a crosslinkable polymerizable monomer, and t-dodecyl mercaptan 1.2 as a molecular weight regulator Part was added, mixed and dissolved to prepare a polymerizable monomer composition.

  On the other hand, an aqueous solution in which 6.2 parts of sodium hydroxide is dissolved in 80 parts of ion-exchanged water and an aqueous solution in which 6.2 parts of sodium hydroxide are dissolved are gradually added at room temperature to an aqueous solution in which 15.5 parts of magnesium chloride are dissolved in 250 parts of ion-exchanged water. Then, a magnesium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion was prepared.

  The polymerizable monomer composition was charged into the magnesium hydroxide colloid dispersion at room temperature and stirred until uniform. After adding 5 parts of t-butylperoxy-2-ethylhexanoate (trade name “Perbutyl O”, manufactured by NOF Corporation) as a polymerization initiator, an in-line type emulsifying disperser (manufactured by Ebara Corporation, product) No. “Ebara Milder”) was dispersed by high-speed shearing stirring for 10 minutes at a rotational speed of 15,000 rpm to form droplets of the polymerizable monomer composition.

  A suspension in which droplets of the polymerizable monomer composition are dispersed (polymerizable monomer composition dispersion) is charged into a reactor equipped with a stirring blade, and then 0.1 part of hydroquinone and After adding an aqueous solution consisting of 24 parts of ion-exchanged water, the temperature was raised to 90 ° C. to initiate the polymerization reaction. 2,2′- which is a polymerization initiator for shell dissolved in 0.7 part of methyl methacrylate as a polymerizable monomer for shell and 10 parts of ion-exchanged water when the polymerization conversion rate reaches almost 100%. 0.07 part of azobis (2-methyl-N- (2-hydroxyethyl) -propionamide) (manufactured by Wako Pure Chemical Industries, Ltd., trade name “VA-086”, water-soluble) was added and the mixture was added at 90 ° C. for 4 hours. After continuing the reaction, the reaction was stopped by cooling with water to obtain an aqueous dispersion of colored resin particles having a core-shell structure.

  Sulfuric acid was added dropwise to the aqueous dispersion of the colored resin particles while stirring at room temperature, and acid washing was performed until the pH became 6.5 or lower. Subsequently, filtration separation was performed, 500 parts of ion-exchanged water was added to the obtained solid content to make a slurry again, and water washing treatment (washing, filtration, and dehydration) was repeated several times. Subsequently, filtration separation was performed, and the obtained solid content was put in a container of a dryer and dried at 45 ° C. for 48 hours to obtain dried colored resin particles. The volume average particle size (Dv) of the obtained colored resin particles is 7.1 μm, the number average particle size (Dn) is 6.3 μm, the particle size distribution (Dv / Dn) is 1.12, and the average circularity is It was 0.987.

  To 100 parts of the colored polymer particles after drying, 0.8 part of silica fine particles (product name: RX200, manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 14 nm that has been subjected to a hydrophobic treatment is added and mixed using a Henschel mixer. The color toner for developing an electrostatic image of Example 1 was produced. The evaluation results of the obtained color toner are shown in Table 1.

[Example 2]
In Example 1, except that 2 parts of the block copolymer 12 as a dispersant was changed to 2 parts of the block copolymer 2 synthesized in Production Example 2, the same procedure as in Example 1 was repeated. A color toner for developing an electrostatic image was produced. The evaluation results of the obtained color toner are shown in Table 1.

[Example 3]
In Example 1, C.I. which is one of benzimidazolone pigments. I. 6 parts of Pigment Yellow 180 (manufactured by Clariant, trade name “toner yellow HG”) is a C.I. I. Pigment Red 122 (made by DIC, trade name “FASTOGEN SUPER MAGENTA RG”) changed to 6 parts, and addition amount of block copolymer 1 as a dispersant changed from 2 parts to 0.5 parts Except for the above, the electrostatic toner image developing color toner of Example 3 was produced in the same manner as in Example 1. The evaluation results of the obtained color toner are shown in Table 1.

[Comparative Example 1]
In Example 1, except that 2 parts of the block copolymer 12 as a dispersant was changed to 2 parts of the random copolymer synthesized in Production Example 3, the static of Comparative Example 1 was obtained in the same manner as in Example 1. A color toner for charge image development was produced. The evaluation results of the obtained color toner are shown in Table 1.

[Comparative Example 2]
In Example 1, except that 2 parts of the block copolymer 12 as a dispersant was changed to 2 parts of a modified polyurethane (trade name “EFKA4080”, manufactured by BASF) as a commercially available polymer dispersant. In the same manner as in Example 1, an electrostatic image developing color toner of Comparative Example 2 was produced. The evaluation results of the obtained color toner are shown in Table 1.

[Comparative Example 3]
In Example 1, an electrostatic image developing color toner of Comparative Example 3 was produced in the same manner as in Example 1 except that 12 parts of the block copolymer 12 as a dispersant was not used. The evaluation results of the obtained color toner are shown in Table 1.

[Comparative Example 4]
In Example 1, C.I. which is one of benzimidazolone pigments. I. 6 parts of Pigment Yellow 180 (manufactured by Clariant, trade name “toner yellow HG”) is a C.I. I. Pigment Red 122 (manufactured by DIC, trade name “FASTOGEN SUPER MAGENTA RG”) was changed to 6 parts, and Example 1 was used except that 12 parts of block copolymer 12 as a dispersant was not used. Similarly, a color toner for developing an electrostatic charge image of Comparative Example 4 was produced. The evaluation results of the obtained color toner are shown in Table 1.

4). Evaluation of Color Toner Physical properties of the color toners for developing electrostatic images in Examples 1 to 3 and Comparative Examples 1 to 4 and the colored resin particles used in these color toners were examined. Details are as follows. As for the electrostatic toner for developing electrostatic images of Comparative Examples 1 to 3, as described later, the volume average particle diameter (Dv), the number average particle diameter (Dn), and the particle size distribution of the colored resin particles ( From the value of Dv / Dn), the aggregation of colored resin particles was clearly observed. Therefore, “4-3. Measurement of Print Density and Evaluation of Saturation (c ^* )” was not performed for the color toners for developing electrostatic images of Comparative Examples 1 to 3.

4-1. Measurement of volume average particle diameter (Dv) and number average particle diameter (Dn) of colored resin particles and calculation of particle size distribution (Dv / Dn) About 0.1 g of a measurement sample (colored resin particles) is weighed and placed in a beaker. Then, 0.1 mL of an alkylbenzenesulfonic acid aqueous solution (manufactured by Fuji Film, trade name “Dry Well”) was added as a dispersant. After adding 10-30 mL of Isoton II to the beaker and dispersing for 3 minutes with a 20 W (Watt) ultrasonic disperser, use a particle size analyzer (Beckman Coulter, trade name “Multisizer”). The volume average particle diameter (Dv) and the number average particle diameter (Dn) of the colored resin particles are measured under the conditions of aperture diameter: 100 μm, medium: Isoton II, number of measured particles: 100,000 particles, The diameter distribution (Dv / Dn) was calculated.

4-2. Average circularity of colored resin particles 10 mL of ion-exchanged water is put in a container in advance, 0.02 g of a surfactant (alkylbenzenesulfonic acid) is added as a dispersant, and 0.02 g of a measurement sample (colored resin particles) is further added. Then, the dispersion treatment was performed with an ultrasonic disperser at 60 W (Watt) for 3 minutes. The concentration of the colored resin particles at the time of measurement is adjusted to 3,000 to 10,000 particles / μL, and 1,000 to 10,000 colored resin particles having an equivalent circle diameter of 0.4 μm or more are flow-type particle images. Measurement was performed using an analyzer (trade name “FPIA-2100” manufactured by Simex Co., Ltd.). The average circularity was determined from the measured value.
The circularity is shown in the following calculation formula 1, and the average circularity is an average of the circularity.
Formula 1: (Circularity) = (Perimeter of circle equal to projected area of particle) / (Perimeter of projected image of particle)

4-3. Measurement of Print Density and Evaluation of Saturation (c ^* ) Using a commercially available non-magnetic one-component developing type printer, the printer has a solid image toner amount (M / A) of 0.4 mg / cm ² on the paper surface. After the adjustment, 100 g of the toner for developing an electrostatic charge image was filled in a toner cartridge in the developing device of the printer. Next, the temperature of the fixing roll (fixing temperature) was set to 180 ° C., and a 5 cm square solid image was printed on plain paper for copying machines (80 g / m ² ). The obtained 5 cm square solid image was measured using a reflection type image densitometer (manufactured by Macbeth, trade name “RD914”).
Further, the solid image was measured with a spectral color difference meter (manufactured by Nippon Denshoku Co., Ltd., trade name “SE-2000”) by expressing the color tone as coordinates in L ^* a ^* b ^* space. The saturation (c ^* ) was determined from the color tone according to the following formula (A).
(C ^* ) ² = (a ^* ) ² + (b ^* ) ² formula (A)

  Table 1 shows the measurement and evaluation results of the color toners for developing electrostatic images in Examples 1 to 3 and Comparative Examples 1 to 4 together with the type and content of the dispersant. In Table 1 below, “PY180” is C.I. I. Pigment Yellow 180, “PR122” is C.I. I. Pigment Red 122 is shown respectively. In Table 1 below, “amine content” means, in the case of block copolymers 1 and 2, the content of the 4-vinylpyridine monomer unit block in the block copolymer, the random copolymer weight. In the case of coalescence, the content of 4-vinylpyridine monomer units in the random copolymer is shown.

5. Evaluation of Toner Hereinafter, with reference to Table 1, the evaluation result of the toner for developing an electrostatic image will be examined.
From Table 1, the toner of Comparative Example 1 is a color toner produced by using 2 parts by mass of a random copolymer having an amine content of 3 mol% with respect to 100 parts by mass of the polymerizable monomer.
From Table 1, the toner of Comparative Example 1 has a large volume average particle size (Dv) of 16.7 μm, a number average particle size (Dn) of 9.1 μm, and a particle size distribution (Dv / Dn). As wide as 1.84. In particular, the volume average particle diameter (Dv) of the toner of Comparative Example 1 is the largest among the toners of Examples 1 to 3 and Comparative Examples 1 to 4. Therefore, agglomeration is clearly observed in the colored resin particles containing a copolymer containing a vinylpyridine monomer unit and a random arrangement order as a dispersant. In addition, in the color toner of Comparative Example 1 manufactured using such colored resin particles, it is considered that the particle size is significantly increased and the shape of the toner particles is uneven.

From Table 1, the toner of Comparative Example 2 is a color toner produced using 2 parts by mass of the modified polyurethane with respect to 100 parts by mass of the polymerizable monomer.
From Table 1, the toner of Comparative Example 2 has a large volume average particle diameter (Dv) of 12.0 μm, a number average particle diameter (Dn) of 6.7 μm, and a particle diameter distribution (Dv / Dn). As wide as 1.79. Therefore, aggregation is clearly observed in the colored resin particles containing the modified polyurethane as a dispersant. Further, in the color toner of Comparative Example 2 manufactured using such colored resin particles, it is considered that the particle size is significantly increased and the shape of the toner particles is uneven.

From Table 1, the toners of Comparative Example 3 and Comparative Example 4 are both color toners manufactured without using a dispersant.
From Table 1, the toner of Comparative Example 3 has a volume average particle size (Dv) of 13.2 μm, a number average particle size (Dn) of 6.4 μm, and a particle size distribution (Dv / Dn). As wide as 2.06. In particular, the particle size distribution (Dv / Dn) of the toner of Comparative Example 3 is the widest among the toners of Examples 1 to 3 and Comparative Examples 1 to 4. Therefore, aggregation is clearly observed in the colored resin particles containing the benzimidazolone pigment and no dispersant. In addition, in the color toner of Comparative Example 3 manufactured using such colored resin particles, it is considered that the particle size is enlarged and the shape of the toner particles is extremely uneven.

From Table 1, the toner of Comparative Example 4 has a volume average particle size (Dv) of 7.2 μm, a number average particle size (Dn) of 6.4 μm, and a particle size distribution (Dv / Dn) of 1. 13. Therefore, there is no particular problem with the shape of the toner particles.
However, from Table 1, the toner of Comparative Example 4 has a reflection ID of 1.01 and a saturation c ^* of 72.4. The values of these reflection ID and chroma c ^* are the values of the reflection ID and chroma c ^* of the toner of Example 3 produced by the same production method as in Comparative Example 4 except that the block copolymer 1 was used. Lower than. Therefore, it can be seen that the toner of Comparative Example 4 is inferior in printing density and image saturation than the toner of Example 3.

On the other hand, as shown in Table 1, the toners of Examples 1 to 3 are each composed of 2 parts by mass of a block copolymer containing 4-vinylpyridine monomer units with respect to 100 parts by mass of the polymerizable monomer. Alternatively, it is a color toner produced using 0.5 parts by mass.
From Table 1, the toners of Examples 1 to 3 have small volume average particle diameters (Dv) of 5.8 to 7.1 μm and number average particle diameters (Dn) of 5.2 to 6.3 μm. The particle size distribution (Dv / Dn) is as narrow as 1.11 to 1.14. Further, from Table 1, the toners of Examples 1 to 3 have a high reflection ID of 1.10 to 1.37 and a saturation c ^* of 73.6 to 94.5.
Therefore, the toners of Examples 1 to 3 containing a quinacridone pigment or a benzimidazolone pigment as a colorant and a block copolymer 1 or 2 having a 4-vinylpyridine monomer unit block as a dispersant are It can be seen that the toner is a color toner in which the aggregation of toner particles is suppressed, the particle size distribution is narrow, and the print density and image saturation are superior to those of the prior art.

Claims (4)

A polymerizable monomer composition containing at least a polymerizable monomer and a colorant is suspended in an aqueous dispersion to obtain a suspension in which droplets of the polymerizable monomer composition are dispersed. A method for producing a color toner for developing an electrostatic charge image, comprising a suspension step, and a step of performing suspension polymerization on the suspension in the presence of a polymerization initiator to obtain colored resin particles,
In the suspension step, at least one of a quinacridone pigment and a benzimidazolone pigment is used as a colorant, and a vinylpyridine monomer unit is used as a dispersant for dispersing the colorant in the polymerizable monomer composition. A method for producing a color toner for developing an electrostatic charge image, comprising using a block copolymer having a block content of 0.5 to 20 mol% . 2. The method for producing a color toner for developing an electrostatic charge image according to claim 1 , wherein the block copolymer further comprises a (meth) acrylic acid ester monomer unit block. Method of production of electrodes for color toners charge image developing of claim 1 or 2, wherein the block copolymer further having an alkylene oxide monomer unit blocks. The said suspension process WHEREIN: 0.2-4 mass parts of said block copolymers are added with respect to 100 mass parts of polymerizable monomers, The Claim 1 thru | or 3 characterized by the above-mentioned. A method for producing a color toner for developing an electrostatic image.