JP4118796B2 - Color toner for electrostatic latent image development - Google Patents

Description

  The present invention relates to a color toner for developing an electrostatic latent image.

  An image forming apparatus using an electrophotographic method such as a laser printer, an LED (Light Emitting Diode) printer, and a copying machine uniformly charges the surface of a photosensitive member, and the surface is irradiated with a laser beam, an LED, or the like. Irradiation forms an electrostatic latent image corresponding to the image information, develops the electrostatic latent image with toner to form a visible image, and transfers the visible image to a recording material to fix it. Form an image on top.

  An electrophotographic image forming apparatus is easy to operate, has a high recording speed, has an image quality that is necessary and sufficient, and can record images on plain paper, so it has good image storage stability. It is an OA device that has the advantage of being indispensable at present. Furthermore, recently, an electrophotographic image forming apparatus capable of recording a full-color image has been put into practical use and is becoming widespread. However, there is room for improvement in terms of color reproducibility (saturation), color development (coloring density), sharpness, etc., when comparing a full-color image by an electrophotographic method with a normal silver salt photograph, printed matter, and the like. Accordingly, as full-color images are generally formed by electrophotography, the demand for image quality is increased, and high image quality equivalent to or higher than that of silver halide photography is required.

  In addition, with the remarkable progress of display technology such as liquid crystal and high-definition, it becomes possible to display an extremely high-definition full-color image on the display, and the image on the display is recorded with good reproducibility by electrophotography. It is strongly demanded.

  In color image formation by electrophotography, for example, light from a color image of a document is first subjected to analog or digital color separation. Light from a color image is usually separated into multiple colors. Information on the first color is guided to the photoconductive layer of the photoconductor to form an electrostatic latent image, and the toner corresponding to the first color is transferred to a transfer material such as paper through a development process using toner and a transfer process to a recording material. Adhere on. Further, the above-described steps are repeated for the second and subsequent colors, and after fixing a plurality of color images on the same transfer material, fixing is performed to form a final full-color image. Here, as the toner, generally three colors of magenta, cyan, and yellow which are three primary colors, or four colors of black for inking with these three colors as necessary are used. Such a toner is required to be excellent in various properties such as chargeability, fluidity, sharpness, and color reproducibility. Furthermore, when a full-color image is formed on a transparent substrate such as a sheet for an overhead projector (hereinafter referred to as “OHP”), an electrophotographic image forming apparatus is frequently used. In this case, as described above, a full color image is formed by superimposing a plurality of color toners. If the transparency (light transmittance) of each toner is insufficient, the color reproducibility is lowered and a clear full color image is obtained. It becomes difficult to obtain an image. Toner transparency is particularly important in high pigment concentration toners created to reduce toner consumption.

  As a method for improving the transparency of the toner, for example, it is conceivable to reduce the particle diameter of the pigment and improve the dispersibility of the pigment in the toner. However, the pigment exists as coarse secondary particles in which the primary particles are aggregated, and its dispersibility is insufficient. In order to return the pigment to the original primary particles, mixing of the synthetic resin and the pigment in the toner production process is performed in an organic solvent using a dispersing machine such as a sand mill, a three-roll mill, a ball mill, and an extruder. However, simply by mechanically dispersing the pigment, the pigment cannot be returned to the primary particles, and it is difficult to improve the dispersibility of the pigment.

  In addition, in order to improve the dispersibility of the pigment, a binder resin and a pigment are used, and when a toner is produced by an emulsion dispersion method, polyester, polystyrene, poly (meth) acrylic is added to a part or all of the binder resin. It has been proposed to use a graft polymer obtained by graft polymerization of a styrene monomer, a (meth) acrylic acid ester monomer, a vinyl ester monomer, or the like on a polymer main chain such as an acid ester polymer or an epoxy resin ( For example, see Patent Document 1). The graft polymer has a certain degree of pigment dispersion effect as compared with the conventional toner binder resin, but the effect does not reach a satisfactory level. In order to improve the pigment dispersion effect, there is a limit to improving the dispersibility even if the graft ratio is increased. Further, if the graft ratio is increased too much, characteristics required as a binder resin are deteriorated, and particularly, the fixing property of the toner to the transfer material and the image quality are deteriorated.

  In addition, it has been proposed that the pigment is surface-treated (coated) with a pigment surface treatment agent containing a functional group such as an amino group, an amide group, an organic dye residue, or an organic heterocyclic residue (for example, patent document). 2, Patent Document 3, Patent Document 4, and Patent Document 5). Many of these functional groups are polar groups, and polar groups have the property of adsorbing moisture in the air. Water adsorbed by the polar group adversely affects the charging stability of the toner. Therefore, the polar group impairs the charging stability of the toner, and the tendency is remarkable especially under high humidity. For this reason, if the amount of polar groups on the pigment surface is increased to an extent that is effective for improving pigment dispersibility and good transparency is imparted to the toner, a reduction in charging stability is inevitable. When the charging performance of the toner becomes unstable, defects such as color unevenness and whiteout occur in the image. On the other hand, if the charge stability is to be maintained, the amount of polar groups decreases, the pigment cannot be uniformly dispersed, and the desired transparency cannot be obtained. Further, since the conventional color toner to which a polar group is added adsorbs moisture in the air regardless of the amount of the polar group, it is inevitable that the charging performance of the toner deteriorates when stored for a long period of time. Of the functional groups listed in the above-mentioned patent documents, those not polar groups are insufficient in improving the pigment dispersibility.

JP-A-5-119529 JP-A-11-84727 JP-A-11-72958 Japanese Patent Laid-Open No. Hei 6-289652 JP 2002-226727 A

  The object of the present invention is to have both transparency and charging stability at a very high level, and also excellent in color reproducibility. For example, it can be suitably used to form a full-color image in an electrophotographic image forming apparatus. To provide a toner for developing an electrostatic latent image.

  In the color toner for developing an electrostatic latent image containing at least a binder resin and a pigment, the present invention is such that a pigment surface treatment agent having a thermally decomposable polar group adheres to a part or all of the pigment surface, and heat per gram of toner. A color toner for developing an electrostatic latent image, having a decomposable polar group content of 1.0 KOH mg or less.

  The color toner for developing an electrostatic latent image of the present invention is characterized in that the pigment surface treatment agent having a thermally decomposable polar group is a synthetic resin having a thermally decomposable polar group.

  Furthermore, the color toner for developing an electrostatic latent image of the present invention is characterized in that the pigment surface treatment agent having a thermally decomposable polar group is an acrylic resin or an epoxy resin having a thermally decomposable polar group.

〔式中、Ｒ^１およびＲ^２は同一または異なって、炭素数１〜６のアルキル基、炭素数１〜６のアルカノール基、フェニル基またはヒドロキシフェニル基を示す。Ｒ^３は炭素数１〜４のアルキル基、炭素数１〜４のアルカノール基、フェニル基またはヒドロキシフェニル基を示す。〕
で表わされるスルホニウム塩基であることを特徴とする。 Further, in the color toner for developing an electrostatic latent image of the present invention, the thermally decomposable polar group has a general formula

[Wherein, R ¹ and R ² are the same or different and each represents an alkyl group having 1 to 6 carbon atoms, an alkanol group having 1 to 6 carbon atoms, a phenyl group, or a hydroxyphenyl group. R ³ represents an alkyl group having 1 to 4 carbon atoms, an alkanol group having 1 to 4 carbon atoms, a phenyl group, or a hydroxyphenyl group. ]
It is the sulfonium base represented by these.

  Furthermore, the color toner for developing an electrostatic latent image of the present invention is characterized in that a monomer containing an alkyl group having 12 or more carbon atoms is further graft-polymerized to a pigment surface treatment agent having a thermally decomposable polar group.

  Furthermore, the color toner for developing an electrostatic latent image according to the present invention is characterized in that the pigment surface treating agent having a thermally decomposable polar group has a weight average molecular weight of 3000 or more and 25000 or less.

  Furthermore, the color toner for developing an electrostatic latent image of the present invention is characterized in that the pigment is a pigment whose surface is modified to be acidic.

  According to the present invention, a color toner containing a pigment and a binder resin, the pigment surface treatment agent having a thermally decomposable polar group attached to part or all of the pigment surface, and the thermally decomposable polarity of the pigment surface An electrostatic latent image developing color toner having a base amount of 1.0 KOHmg / g or less per gram of toner is provided.

  In the present invention, by mixing the pigment and the binder resin in the presence of the pigment surface treatment agent having a thermally decomposable polar group, the pigment surface treatment agent adheres to a part or the entire surface of the pigment. The pigment is uniformly dispersed in the binder resin, and the heat-decomposable polar group is decomposed by heating during mixing of the pigment and the binder resin, and converted to an organic group that does not impair the charging stability of the toner. Therefore, the pigment can be uniformly dispersed in the binder resin without impairing the charging stability of the obtained toner.

  Therefore, the color toner for developing an electrostatic latent image according to the present invention has both excellent transparency and charging stability, and excellent color reproducibility. For example, it is extremely useful as a color toner for recording a full color image by electrophotography. It can be used suitably. By using the color toner of the present invention, it is possible to easily record a full color image with excellent transparency, good color reproducibility and color developability, high sharpness and high image quality. Furthermore, since the color toner of the present invention does not contain polar groups that affect charging stability, charging performance does not deteriorate even after long-term storage, and a full-color image equivalent to that before storage is recorded. can do.

  According to the present invention, among pigment surface treatment agents having a thermally decomposable polar group, a synthetic resin having a thermally decomposable polar group is preferred. By using this, a thermally decomposable polar group adheres uniformly to the pigment surface, and the dispersibility of the pigment is further improved.

  According to the present invention, among the pigment surface treatment agents having a thermally decomposable polar group, an acrylic resin or an epoxy resin having a thermally decomposable polar group is preferable. These are excellent in affinity with the pigment. Moreover, since it is easy to introduce a thermally decomposable polar group into an acrylic resin or an epoxy resin, it also has an advantage of easy production.

  According to the present invention, in the pigment surface treating agent having a thermally decomposable polar group, the thermally decomposable polar group is a sulfonium base represented by the general formula (1) (hereinafter referred to as “sulfonium base (1)”). Is preferred. The sulfonium base (1) can impart good dispersibility to the pigment, and after the pigment is dispersed in the binder resin, it is decomposed by heating at the time of mixing the pigment and the binder resin, and the charging stability of the toner. It is converted to a sulfide group that does not affect.

  According to the present invention, in the synthetic resin having a thermally decomposable polar group, the dispersibility of the pigment is further improved by using a synthetic resin having a weight average molecular weight of 3000 or more and 25000 or less.

  According to the present invention, the pigment surface treatment agent having a thermally decomposable polar group is graft-polymerized with a monomer containing an alkyl group having 12 or more carbon atoms, thereby further preventing re-aggregation of the pigment and improving the transparency of the toner. Maintained at a higher level.

  According to the present invention, when a pigment surface treatment agent having a basic group with a thermally decomposable polar group is used by using a pigment whose surface is modified to be acidic, for example, a pigment having an acidic group on the surface, the pigment The dispersibility in the binder resin is further improved. The reason is not clear, but the acidic group on the pigment surface interacts with the basic group on the pigment surface treatment agent to increase the affinity between the pigment and the pigment surface treatment agent. It is presumed that the adsorption state is the result of stabilization.

  The toner for developing an electrostatic latent image of the present invention contains a pigment and a binder resin as essential components, and a pigment surface treatment agent having a thermally decomposable polar group adheres to a part or the whole of the pigment surface. The amount of the thermally decomposable polar group is 1.0 KOH mg / g or less, preferably 0.9 KOH mg / g or less, more preferably 0.8 KOH mg / g or less. When the content of the thermally decomposable polar group exceeds 1.0 KOHmg / g, as described above, the thermally decomposable polar group adsorbs water, and the charging stability of the toner decreases.

  The pigment used in the toner of the present invention is not particularly limited, and known black pigments and chromatic pigments can be used. Examples of the black pigment include black inorganic pigments typified by carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black. Examples of chromatic pigments include organic pigments. If an example of an organic pigment is shown by a color index number, for example, phthalocyanine type C.I. I. Pigment Blue 15-3, Indanthrone C.I. I. Pigment Blue 60 and other blue organic pigments, quinacridone C.I. I. Pigment Red122, an azo-based C.I. I. Pigment Red22, C.I. I. PigmentRed 48: 1, C.I. I. Pigment Red 48: 3, C.I. I. Pigment Red 57: 1, red organic pigments such as azo-based C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 17, an isoindolinone-based C.I. I. Pigment Yellow 110, a benzimigusolone-based C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow154, C.I. I. And yellow organic pigments such as Pigment Yellow 180. A pigment can be used individually by 1 type or can use 2 or more types together. Two or more same color pigments may be used.

  In the present invention, a pigment whose surface is modified to be acidic can be used. When such a pigment is used, the dispersibility of the pigment can be improved. As the pigment whose surface is modified to be acidic, one or more kinds selected from anionic acidic functional groups such as sulfonic acid group, sulfinic acid group, carboxylic acid group, phosphoric acid group and salts thereof on the surface Examples thereof include pigments into which an acidic group has been introduced. In order to introduce these acidic groups into the pigment, known methods can be employed. For example, acid treatment (such as a method of direct treatment with fuming sulfuric acid or chlorosulfonic acid in the atmosphere or in a wet manner), and an acidic group on the pigment surface. Examples thereof include a method of grafting a polymer.

  The content of the pigment in the color toner of the present invention is not particularly limited and can be appropriately selected from a wide range depending on the kind of the pigment, but is usually 5 to 15% by weight, preferably 7 to 13% by weight of the total amount of the color toner. It is. If it is significantly less than 5% by weight, a larger amount of toner than usual may be required to form an image having a constant density. On the other hand, if it exceeds 15% by weight, the transparency of the toner may be lowered.

  As the binder resin, a synthetic resin commonly used in this field can be used, and among them, a thermoplastic resin compatible with the pigment surface treatment agent having a thermally decomposable polar group is preferable. Such a thermoplastic resin is not particularly limited, and examples thereof include styrenes such as styrene, parachlorostyrene, and α-methylstyrene, methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, and acrylic acid. Acrylic monomers such as 2-ethylhexyl, methacrylic monomers such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, acrylic acid, methacrylic acid, styrene sulfone Ethylenically unsaturated acid monomers such as sodium acid, vinyl nitriles such as acrylonitrile and methacrylonitrile, vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl iso Vinyl resins which are homopolymers and copolymers containing one or more monomers selected from polymerizable double bond-containing monomers such as vinyl ketones such as lopenyl ketone and olefins such as ethylene, propylene and butadiene, Non-vinyl condensation resin such as epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, mixture of non-vinyl condensation resin and vinyl resin, coexistence of non-vinyl condensation resin and vinyl resin Examples thereof include graft polymers obtained by graft polymerization of vinyl monomers. Moreover, it can also superpose | polymerize by the heating at the time of mixing with a pigment using the 1 type (s) or 2 or more types of the said polymerizable double bond containing monomer. Among these, polyester resins and polyether resins are preferable in view of further improving the transparency and durability of the toner obtained.

  In the pigment surface treatment agent having a thermally decomposable polar group, the thermally decomposable polar group is not particularly limited as long as it is a polar group having thermal decomposability, but the effect of improving the dispersibility of the pigment in the binder resin In view of the thermal decomposition temperature and the like, a cationic thermally decomposable polar group such as a quaternary ammonium base or a sulfonium group is preferable. Among these, a sulfonium group is particularly preferable. The sulfonium group can remarkably improve the dispersibility of the pigment. Further, the sulfide group generated by the thermal decomposition has a low polarity and hardly adsorbs water, so that the charging stability of the toner can be maintained at a high level. In addition, the sulfide group interacts with the metal in the pigment and the thermally decomposable polar group remaining on the pigment surface to increase the dispersibility of the pigment and prevent the pigment from reaggregating even if the polar group concentration decreases. can do. Furthermore, since the sulfonium group has a relatively low thermal decomposition temperature and is close to the mixing temperature of the pigment and the binder resin, it is suitable for producing the color toner of the present invention.

Specific examples of the sulfonium group include the aforementioned sulfonium base (1). The sulfonium base (1) is thermally decomposed at around 150 ° C., which is approximately the same as the heating temperature at the time of mixing the pigment and the binder resin, with the advantages of improving pigment dispersibility and generating sulfide groups by thermal decomposition. Therefore, there is an advantage that a special process for thermal decomposition is not required. In the thermal decomposition of the sulfonium base (1), counter ions (COO ⁻ ) are released into the system, and carboxylic acid is generated. Since this carboxylic acid is a low molecular weight compound and is scattered outside the system by heating during mixing, it does not affect the charging stability of the toner.

In the general formula (1), the alkyl group having 1 to 6 carbon atoms represented by the symbols R ¹ and R ² includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, C1-C6 linear or branched alkyl such as tert-butyl group, sec-butyl group, n-pentyl group, tert-pentyl group (amyl group), n-hexyl group, tert-hexyl group Groups. Examples of the alkanol group having 1 to 6 carbon atoms represented by R ¹ and R ² include hydroxymethyl group, hydroxyethyl group, hydroxy n-propyl group, hydroxyisopropyl group, hydroxy n-butyl group, hydroxy sec-butyl group, hydroxy Examples thereof include an alkanol group in which a hydroxy group is substituted on a linear or branched alkyl group having 1 to 6 carbon atoms such as a tert-butyl group, a hydroxy n-pentyl group, and a 1-hydroxyhexyl group.

In the general formula (1), the alkyl group having 1 to 4 carbon atoms represented by the symbol R ³ includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. A linear or branched alkyl group having 1 to 4 carbon atoms, such as a group or a sec-butyl group. Examples of the alkanol group having 1 to 4 carbon atoms represented by R ³ include a hydroxymethyl group, a hydroxyethyl group, a hydroxy n-propyl group, a hydroxyisopropyl group, a hydroxy n-butyl group, a hydroxy sec-butyl group, and a hydroxy tert-butyl group. Examples thereof include alkanol groups in which a linear or branched alkyl group having 1 to 4 carbon atoms such as a group is substituted with a hydroxy group.

  By using such a pigment surface treating agent having a thermally decomposable polar group, both uniform dispersion of the pigment in the binder resin and prevention of deterioration of charging stability, which could not be achieved by the prior art, are simultaneously achieved. It becomes possible.

  Among pigment surface treatment agents having a thermally decomposable polar group, a synthetic resin having a thermally decomposable polar group is preferable, considering that it is easy to manufacture, has an affinity with the pigment, and is excellent in the coverage with respect to the pigment. Particularly preferred are acrylic resins and epoxy resins having a thermally decomposable polar group. Moreover, as a thermally decomposable polar group, 1 type (s) or 2 or more types, such as a quaternary ammonium base and a sulfonium base, are preferable, and a sulfonium base (1) is especially preferable.

  The pigment surface treatment agent having a thermally decomposable polar group can be produced according to a known method. An acrylic resin having a quaternary ammonium base can be produced, for example, by copolymerizing a polymerizable double bond-containing monomer and a tertiary amino group-containing monomer and reacting the resulting copolymer with a quaternizing agent. . Here, known monomers can be used as the polymerizable double bond-containing monomer. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl ( (Meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, cyclohexyl (meth) acrylate, butoxymethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, benzyl (meth) acrylate, Cetyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene glycol (meth) acrylate (Meth) acrylic esters such as relate, aromatic vinyls such as styrene, divinylbenzene, α-methylstyrene, vinyl esters such as vinyl acetate, vinyl benzoate, vinyl versatic acid, vinyl propionate, (meth) Polymerizable nitriles such as acrylonitrile, vinyl atom-containing vinyl monomers such as vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, fluoroalkyl group-containing (meth) acrylic acid esters, 2 -(2'-hydroxy-5-methacryloyloxyethylphenyl) -2H-benzotriazole, 2-hydroxy-4- (2-methacryloyloxyethoxy) benzophenone, 1,2,2,6,6-pentamethyl-4-piperidyl Mekakuri Examples thereof include monomers having ultraviolet absorptivity or antioxidant properties such as a rate, and (meth) acrylamides such as N-vinylpyrrolidone, diacetone acrylamide, N-methylol acrylamide, and N-butoxymethyl (meth) acrylamide. The polymerizable double bond-containing monomer can be used alone or in combination of two or more. As the tertiary amino group-containing monomer, known monomers can be used, such as diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl methacrylamide, N-vinylimidazole, N-vinylcarbazole and the like. It is done. A tertiary amino group-containing monomer can be used alone or in combination of two or more.

  The copolymerization reaction between the polymerizable double bond-containing monomer and the tertiary amino group-containing monomer is performed, for example, in the presence of a radical polymerization initiator according to a known polymerization method such as solution polymerization, suspension polymerization, or emulsion polymerization. . Examples of the radical polymerization initiator include sulfites such as ammonium sulfite, potassium sulfite and sodium sulfite, peroxides such as potassium persulfate, sodium persulfate and ammonium persulfate, azobisisobutyronitrile, 2,2′- Azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 1,1′-azobis (1-cyclohexanecarbonitrile), 4,4′-azobis (4-cyano Valeric acid), 1,1′-azobis (1-acetoxy-1-phenylethane), 2,2′-azobis (2-methylbutyramide), 1,1′-azobis (methyl 1-cyclohexanecarboxylate), etc. And the azo compound. A commercial item can also be used for a radical polymerization initiator. For example, azo compounds commercially available from Wako Pure Chemical Industries, Ltd. under trade names such as V-60, V-65, VA-601, VA-501, Kayaester 0, Kayabutyl B, Laurox, etc. Examples thereof include peroxides marketed by Kayaku Akzo Co., Ltd. under the trade name. A radical polymerization initiator can be used individually by 1 type, or can use 2 or more types together.

  Also, known quaternizing agents can be used such as hydrogen chloride, hydrogen bromide, formic acid, acetic acid, propionic acid, alkylsulfonic acid and other protonic acids, dimethyl sulfate, diethyl sulfate, dipropyl sulfate and the like. Examples thereof include sulfonic acids such as alkyl sulfuric acid and p-toluenesulfonic acid, sulfonic acid esters such as methyl p-toluenesulfonate and methyl benzenesulfonate, alkyl chloride, alkyl bromide, and benzyl chloride. Among these, acetic acid and p-toluenesulfonic acid are preferable. A quaternizing agent can be used individually by 1 type, or can use 2 or more types together. Although the amount of the quaternizing agent used is not particularly limited, it may be appropriately selected from a range of about 20 to 100 mol% with respect to the amount of the tertiary amino group-containing monomer.

  In addition, an acrylic resin having a quaternary ammonium base or a sulfonium base is obtained by copolymerizing a polymerizable double bond-containing monomer and an epoxy group-containing monomer, and converting the resulting copolymer and a tertiary amine compound or sulfide compound to an acid. It can also be produced by reacting in the presence. As the polymerizable double bond-containing monomer, one or two or more selected from those described above can be used. As the epoxy group-containing monomer, known monomers having an epoxy group and a polymerizable double bond can be used, and examples thereof include glycidyl methacrylate, glycidyl acrylate, and allyl glycidyl ether. Epoxy group-containing monomers can be used alone or in combination of two or more. The copolymerization reaction of the polymerizable double bond-containing monomer and the epoxy group-containing monomer is carried out in the same manner as the copolymerization reaction of the polymerizable double bond-containing monomer and the tertiary amino group-containing monomer. Examples of the tertiary amine compound to be reacted with the copolymer thus produced include trimethylamine, methyldiethanolamine, dimethylethanolamine, dimethylbenzylamine and the like. Moreover, as a sulfide compound, for example, general formula R—S—R (wherein R represents an alkyl group having 1 to 6 carbon atoms, an alkanol group having 1 to 6 carbon atoms, a phenyl group, or a hydroxyphenyl group). And sulfide compounds represented. Specific examples of the sulfide compound include dimethyl sulfide, diethyl sulfide, dipropyl sulfide, dibutyl sulfide, diphenyl sulfide, dihexyl sulfide, ethylphenyl sulfide, thiodiethanol, thiodipropanol, and thiodibutanol. Commercially available products can be used as the tertiary amine compound and sulfide compound, and examples thereof include sulfide compounds such as SHP-100 (trade name, manufactured by Sanyo Chemical Industries, Ltd.). A tertiary amine compound and a sulfide compound can be used individually by 1 type, or can use 2 or more types together. Examples of the acid include organic carboxylic acids such as formic acid, acetic acid, lactic acid, propionic acid, butyric acid, and dimethylolpropionic acid. Among these, acetic acid is particularly preferable. This reaction is preferably carried out under heating.

  Furthermore, an epoxy resin having a quaternary ammonium base or a sulfonium base can be produced by reacting an epoxy resin with a tertiary amine compound or a sulfide compound in the presence of an acid. This reaction can be carried out in the same manner as the reaction for obtaining an acrylic resin having a quaternary ammonium base or a sulfonium base.

As described above, when an epoxy group-containing acrylic resin or epoxy resin is reacted with a tertiary amine compound or sulfide compound, the thermally decomposable polar group such as a quaternary ammonium base or sulfonium base is mainly an epoxy in the resin. It is formed by the reaction of a group, glycidyl ester group or the like with a sulfide group or a tertiary amine group. Therefore, the thermally decomposable polar group mainly includes a group —O—R ⁴ — (wherein R ⁴ represents an alkylene group having 1 or more carbon atoms which may have 1 or 2 or more hydroxyl groups), a group —. It bonds to an acrylic resin and an epoxy resin via CO—O—R ⁴ — (wherein R ⁴ is the same as above). Furthermore, thermally decomposable polar groups, group -R 4 ^- (wherein R ⁴ is the same), also be attached to an acrylic resin or epoxy resin through a phenylene group. In each of the above groups, the alkylene group having 1 or more carbon atoms represented by the symbol R ⁴ includes a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, a 1,1-dimethyltetramethylene group, a butylene group, an octane group. Examples include a linear or branched alkylene group such as a methylene group, an octylene group, a decamethylene group, and a decylene group. The alkylene group may have one or more hydroxyl groups in its side chain. Specific examples of the group —O—R ⁴ — include, for example, a group —O—CH ₂ —CH (OH) —CH ₂ —. Specific examples of the group —CO—R ⁴ — include, for example, a group —CO—O—CH ₂ —CH (OH) —CH ₂ —.

  In the present invention, a pigment surface treatment agent having a thermally decomposable polar group can be further graft polymerized with a monomer containing an alkyl group having 12 or more carbon atoms. As a result, the three-dimensional structure of the monomer is stabilized, steric hindrance is generated, the pigments are prevented from reaggregating, and the transparency of the toner can be maintained in a favorable range. As the monomer containing an alkyl group having 12 or more carbon atoms, known monomers can be used. For example, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, polypropylene glycol mono (meth) acrylate, poly (propylene) Glycol-tetramethylene glycol) mono (meth) acrylate, linseed oil fatty acid and other (meth) acrylates containing an alkyl group having 12 or more carbon atoms. These can be used individually by 1 type or can use 2 or more types together. A known method can be employed when graft-polymerizing a monomer containing an alkyl group having 12 or more carbon atoms to a pigment surface treatment agent having a thermally decomposable polar group. For example, a method of grafting via a macromonomer having one polymerizable double bond at the molecular end, or a pigment surface treatment agent containing a hydroxyl group, produced by a ring-opening reaction of a lactone at the hydroxyl group A method of grafting a macromonomer via stearic acid, linseed oil fatty acid, hydroquinone, etc. Can be mentioned. At this time, the grafting rate is not particularly limited, but is usually about 5 to 30%.

  The above copolymerization, graft polymerization and quaternization can also be carried out in a solvent. As the solvent, each monomer, radical polymerization initiator, quaternizing agent, etc. can be dissolved or dispersed, and those inert to the copolymerization reaction can be used. For example, aromatic carbonization such as toluene and xylene. Examples include hydrogen, ester systems such as ethyl acetate and isobutyl acetate, and ketone systems such as methyl ethyl ketone and methyl isobutyl ketone.

  In the production of the pigment surface treatment agent having the above-mentioned thermally decomposable polar group, the pigment surface treatment agent is appropriately selected from the polymerization conditions such as the type of monomer, the proportion of monomer used, the amount of radical polymerization initiator used, and the polymerization temperature. By doing so, for example, it is possible to produce a pigment surface treatment agent having characteristics such as a desired pyrolyzable polar group amount, molecular weight, and glass transition temperature Tg.

  The content of the thermally decomposable polar group in the pigment surface treating agent having a thermally decomposable polar group is not particularly limited, but is usually 10 to 100 mg KOH (10 mg KOH or more, 100 mg KOH or less) per 1 g of the pigment surface treating agent, preferably It is 20-70 mgKOH (20 mgKOH or more, 70 mgKOH or less), More preferably, it is 30-60 mgKOH (30 mgKOH or more, 60 mgKOH or less). If the pyrolyzable polar group content is significantly lower than 10 mgKOH, the affinity between the pigment surface treatment agent having a pyrolyzable polar group and the pigment is reduced, and the amount of pigment adsorbed on the pigment surface treatment agent is reduced. The dispersibility of the pigment may be lowered. On the other hand, if it greatly exceeds 100 mgKOH, extra energy and time are required to bring the content of the thermally decomposable polar group into the range specified in the present invention, which is not industrially preferable.

  The weight average molecular weight of the pigment surface treatment agent having a thermally decomposable polar group is not particularly limited and can be appropriately selected from a wide range. However, the pigment dispersibility in the toner, the fixing property to the transfer material of the toner, the durability, etc. In consideration, it is usually 3000-25000 (3000 or more, 25000 or less), preferably 5000-20000 (5000 or more, 20000 or less), and more preferably 7000-15000 (7000 or more, 15000 or less). When the weight average molecular weight is significantly less than 3000, the steric hindrance due to the pigment surface treatment agent having a thermally decomposable polar group is reduced, and the re-aggregation of the pigment may occur to impair the dispersibility of the pigment. If it greatly exceeds 25000, the pigment surface treatment agent having a thermally decomposable polar group agglomerates the pigment, the dispersibility of the pigment is lowered, and the color transparency and color reproducibility of the obtained toner may be lowered. .

  The amount of the pigment surface treatment agent having a thermally decomposable polar group is not particularly limited. The type of pigment surface treatment agent (particularly the type of thermally decomposable polar group), the type and amount of pigment used, and the pigment and binder resin. Can be appropriately selected from a wide range according to various conditions such as the mixing temperature, but usually 0.1 to 100 parts by weight, preferably 1 to 60 parts by weight, particularly preferably 5 to 50 parts by weight based on 100 parts by weight of the pigment. Parts by weight.

  A fluidity improver can be added to the color toner of the present invention as long as the preferable characteristics are not impaired. The fluidity improver is preferably externally added after the toner particles are formed. The fluidity improver may be adhered to the surface of the toner particles, or a part thereof may be embedded in the toner particles. The external addition of the fluidity improver to the toner particles can be performed using, for example, a normal powder mixer such as a Henschel mixer, or a surface modifier such as a hybridizer. As the fluidity improver, known ones can be used, and examples thereof include hydrophobic silica, zinc stearate, aluminum stearate, titanium oxide and the like. Among these, hydrophobic silica is preferable. Commercially available products of hydrophobic silica include, for example, AEROSILR972, R974, R202, R805, R812, RX200, RY200, R809, RX50 (all trade names, manufactured by Nippon Aerosil Co., Ltd.), WackerHDKH2000, H2050EP (all trade names) , Manufactured by Wacker Chemicals East Asia Co., Ltd.), Nipsil SS-10, SS-15, SS-20, SS-50, SS-60, SS-100, SS-50B, SS-50F, SS-10F, SS-40 , SS-70, SS-72F (both trade names, manufactured by Nippon Silica Kogyo Co., Ltd.) and the like. The particle diameter of the hydrophobic silica is not particularly limited, and may be appropriately selected according to the size of the toner particles to be obtained and the like that meet the purpose of improving fluidity. A fluidity improver can be used individually by 1 type, or can use 2 or more types together as needed. The amount of fluidity improver used is not particularly limited and can be selected from a wide range, but considering the charging performance of the resulting toner, the stability of the toner characteristics to the environment, the effect on the photosensitive drum when the toner is actually used, etc. Then, it is 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the color toner of the present invention.

  Furthermore, the color toner of the present invention may contain various additives conventionally used in toners as long as the preferable characteristics are not impaired. Examples of the additive include a charge control agent, an offset preventing agent, a release agent, and magnetic powder. These additives can be used alone or in combination of two or more.

  Known charge control agents can be used, for example, heavy metals such as nigrosine dyes, quaternary ammonium salts, trimethylethane dyes, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes, etc. Examples thereof include acidic dyes, metal complex compounds of salicylic acid, and metal complex compounds of esters of salicylic acid and alkyl alcohols. Commercially available charge control agents include Bontron S-32, Bontron E-84 (both trade names, manufactured by Orient Chemical Co., Ltd.), Aizen Spilon Black TRH (trade names, manufactured by Hodogaya Chemical Co., Ltd.), LR- 147 (trade name, manufactured by Nippon Carlit Co., Ltd.). Among these, considering that a colorless charge control agent is preferable for color toners, metal complex compounds of salicylic acid and metal complex compounds of esters of salicylic acid and alkyl alcohol are preferable, and commercially available products are Bontron E-84 and LR-147. Corresponds to these. The charge control agent can be used alone or in combination of two or more.

  The offset preventing agent improves, for example, fixability of the obtained toner to a transfer material. As the anti-offset agent, those commonly used in this field can be used. For example, natural wax such as carnauba wax, rice wax, and montanic acid ester wax, polyolefin wax such as high pressure polyethylene wax, polypropylene wax, and silicone wax. And waxes such as fluorine-based waxes. Commercially available offset inhibitors include, for example, Biscol 660P, Biscol 550P, Biscol 330P, and TP32 (all trade names, manufactured by Sanyo Chemical Industries), Mitsui High Wax NP505, P200, P300, and P400 ( All of them include trade names, manufactured by Mitsui Chemicals, Inc.). An offset inhibitor can be used individually by 1 type, or can use 2 or more types together.

  As the release agent, known ones can be used, and examples thereof include polyolefin waxes such as low molecular weight polypropylene wax, low molecular weight polyethylene wax, oxidized polypropylene wax and oxidized polyethylene wax. A mold release agent can be used individually by 1 type, or can use 2 or more types together.

  As the magnetic powder, known powders can be used. For example, a ferromagnetic metal such as ferrite, magnetite or the like, iron, cobalt, nickel or an alloy thereof, or a compound containing these ferromagnetic metals, manganese-copper-aluminum, manganese- Examples include Heusler alloys containing manganese and copper, such as copper-tin, and metal compounds that exhibit ferromagnetism by heat treatment, such as chromium dioxide. Among these, ferrite and magnetite are preferable. The magnetic powder can be subjected to a surface treatment using a coupling agent such as a titanium coupling agent, a silane coupling agent, or lecithin. Magnetic powder can be used individually by 1 type, or can use 2 or more types together.

  The color toner of the present invention can be produced, for example, by mixing and granulating a pigment, a pigment surface treatment agent having a thermally decomposable polar group, and a binder resin.

  Moreover, you may utilize a masterbatch technique. For example, together with the pigment and the pigment surface treatment agent having a thermally decomposable polar group, a binder resin in an amount smaller than a predetermined amount and, if necessary, other additives are heated to such an extent that the thermally decomposable polar group does not decompose. And then granulating to produce a masterbatch containing the pigment in a high concentration, mixing the masterbatch and the remainder of the binder resin under heating, and granulating to produce the color toner of the present invention. Can get.

  In the production of the color toner of the present invention, the content of the thermally decomposable polar group in the pigment surface treatment agent having the thermally decomposable polar group, taking into account the thermal decomposition temperature of the thermally decomposable polar group By appropriately adjusting the addition amount of the pigment surface treatment agent having a thermally decomposable polar group, a color toner having a thermally decomposable polar group amount specified in the present invention can be obtained.

  Mixing is performed using a kneader, for example. As the kneading machine, those commonly used in the production of toner can be used. For example, a general kneading machine such as a twin screw extruder, a triple roll, a lab blast mill, TEM-100B (trade name, Toshiba Machine Co., Ltd.) ), PCM-65 / 87 (trade name, manufactured by Ikegai Co., Ltd.) and other single-screw or twin-screw extruders, and knee rolls (trade name, manufactured by Mitsui Mining Co., Ltd.) Can be mentioned. Among these, in the open roll method, by heating at a relatively low temperature, while maintaining the viscosity of the kneaded material not to decrease too much, a high shear force is applied to the kneaded material to uniformly disperse each component. It is a kneading machine and is suitable for producing the color toner of the present invention. When a pigment surface treatment agent having a thermally decomposable polar group adheres to the pigment surface and mechanical stress (shearing force) is applied to the pigment surface, the pigment particles are agglomerated to become primary particles, and the dispersibility of the pigment is improved. To do. The heating temperature and kneading time at the time of kneading are not particularly limited and can be appropriately selected from a wide range depending on the decomposition temperature of the thermally decomposable polar group, the dispersion state of the toner component, etc., but usually about 150 to 200 ° C. and 10 minutes About 2 hours.

  Granulation can be performed according to a known granulation method of toner particles. For example, the kneaded product obtained by the above mixing is cooled, and the obtained solidified product is finely pulverized by a pulverizer such as a jet mill, and further classified by a classifier such as an air classifier to obtain color toner particles. . Furthermore, the fluidity improver described above may be externally added to the color toner particles to improve the powder fluidity of the color toner particles. Thereby, more practical color toner particles can be obtained.

  In this way, the color toner particles of the present invention can be obtained. Although the particle diameter of the color toner particles of the present invention is not particularly limited, the volume average particle diameter is 3 to 8 μm (3 μm or more and 8 μm or less), preferably 4 to 7 μm (4 μm or more and 7 μm or less), more preferably 5 to 6 μm. (5 μm or more and 6 μm or less) is preferable. When the volume average particle diameter is significantly smaller than 3 μm, the toner particles are scattered to cause white background fog that adheres to the non-image forming portion of the transfer material, and the toner necessary for forming an image with a predetermined image density The amount of adhesion increases and the manufacturing cost also increases significantly. On the other hand, if the thickness exceeds 8 μm, the amount of pigment contained in the toner increases, resulting in uneven color and the like in the image, and color transparency, color reproducibility and gradation are deteriorated.

  In the present specification, the particle diameter of the toner was measured using a Coulter Multisizer II (trade name, manufactured by Coulter, Inc.) with an aperture diameter of 100 μm, preferably 30 μm.

  The color toner of the present invention can be used as a one-component developer and a two-component developer. When used as a one-component developer, for example, when non-magnetic toner is used, there is a method of transporting by using a blade and a fur brush, frictionally charging with a developing sleeve, and attaching the toner onto the sleeve. .

  When used as a two-component developer, a carrier is used as a developer together with the color toner of the present invention. The carrier used together with the color toner of the present invention is not particularly limited, but the surface of single and composite ferrite mainly composed of iron, copper, zinc, nickel, cobalt, manganese, chromium and the like, and carrier core particles are coated with a coating substance. Things are used. The coating material is appropriately selected according to the components contained in the toner. For example, polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, and a metal compound of ditertiary butylsalicylic acid Styrene resin, acrylic resin, polyacid, polyvinyllar, nigrosine, aminoacrylate resin, basic dye and its lake, silica fine powder, alumina fine powder, and the like. A coating substance can be used individually by 1 type, or can use 2 or more types together. The average particle size of the carrier is 10 to 100 μm, preferably 20 to 50 μm.

  Image formation using the color toner of the present invention can be carried out in the same manner as conventional image formation except that the color toner of the present invention is used instead of the conventional color toner. For example, the image forming apparatus 100 shown in FIG. 1 is used. FIG. 1 is a cross-sectional view schematically showing the configuration of the image forming apparatus 100. The image forming apparatus 100 is an apparatus that forms multicolor and single color images on a predetermined transfer material (recording paper) in accordance with image data transmitted from the outside.

  The image forming apparatus 100 includes a paper feeding unit 1, a transfer material transport unit 2, an image forming unit 3, a transfer material discharge unit 4, and a control unit 5.

  The paper feeding unit 1 is provided with a paper feeding tray 10 that accumulates transfer materials and an end of the paper feeding tray 10, and a pickup roller 11 that supplies the transfer materials from the paper feeding tray 10 to the transfer material transport unit 2 one by one. It is comprised including. The transfer material accumulated in the paper feed tray 10 is fed to the transfer material transport unit 2 one by one by the pickup roller 11. The paper feed tray 10 is a tray for storing transfer materials such as plain paper used for image formation, color image dedicated paper, and OHP film, and is provided below the image forming unit 3 of the image forming apparatus 100. Provided.

  The transfer material conveyance unit 2 includes an S-shaped transfer material conveyance path 6 that conveys the transfer material supplied from the paper supply unit 1 to the transfer material discharge unit 4 via the image forming unit 3, and the paper supply unit 1. A registration roller 12 for feeding a transfer material supplied from the image forming unit 3 to the image forming unit 3, a fixing unit 30 for fixing an image formed on the transfer material in the image forming unit 3 to the transfer material, and a transfer in which the image is fixed A conveyance direction switching guide 33 that switches the conveyance direction of the material and a conveyance roller 36 that conveys the transfer material in the transfer material conveyance path 6 and finally discharges it to the outside of the apparatus 100 are configured.

  The registration roller 12 temporarily stores the transfer material supplied from the paper feeding unit 1 in the transfer material conveyance path 12, and synchronizes with the operation of the image forming unit 3 to transfer the transfer material to the image forming unit 3 in a timely manner. Has the function of feeding. Specifically, the registration roller 12 uses the detection signal output by a pre-registration detection switch (not shown) to change the tip of the toner image on the photoconductors 16a, 16b, 16c, and 16d to the tip of the image forming range on the transfer material. The transfer material is set to be conveyed so as to meet the above.

  The fixing unit 30 is rotatably provided, a heat roller 31 that melts the binder resin contained in the toner, and a toner that is rotatably provided so as to be in contact with the heat roller 31 and melted by the heat roller 31. And a pressure roller 32 that fixes the transfer material by applying pressure. Under the rotation of the heat roller 31 and the pressure roller 32, a transfer material on which a toner image is formed by the image forming unit 3 is passed between the heat roller 31 and the pressure roller 32, whereby the toner image is transferred to the transfer material. To fix.

  The conveyance direction switching guide 33 includes a columnar guide shaft 33a provided in a direction orthogonal to the moving direction of the transfer material, and a guide 33b provided movably in the circumferential direction of the guide shaft 33a. . When the conveyance direction switching guide 33 is in the state indicated by the solid line, the transfer material is discharged to the tray 37 outside the upper surface of the apparatus 100 via the transfer material conveyance path 6. When the conveyance direction switching guide 33 is in the state shown by the broken line, the transfer material is discharged to the tray 34 outside the side surface of the apparatus 100 via the transfer material conveyance path 6a.

  The conveyance roller 36 is a small roller for promoting and assisting conveyance of the transfer material, and a plurality of conveyance rollers 36 are provided along the transfer material conveyance path 6.

  In the transfer material transport unit 2, the transfer material once stored in the transfer material transport path 6 is fed to the image forming unit 3 by the registration roller 12 in synchronization with the operation of the image forming unit 3. The transfer material on which the toner image is formed in the image forming unit 3 is fixed in the toner image in the fixing unit 30, and is then distributed in the conveyance direction by the conveyance direction switching guide 33, and is conveyed in the transfer material conveyance paths 6 and 6a. Is done.

  The image forming unit 3 includes an illumination 13 and a sensor 14 that sense that the transfer material is supplied by the transfer material transport unit 2, and an electrophotographic unit 15a that forms a toner image on the transfer material based on the applied image information. 15b, 15c, 15d and the electrophotographic units 15a, 15b, 15c, 15d, a transfer conveyance belt unit 22 that conveys the transfer material, and a transfer conveyance belt unit 22 that is in contact with the transfer conveyance belt unit 22. And a transfer belt cleaning unit 24 that removes toner adhering to the unit 22.

  The illumination 13 and the sensor 14 are provided for sensing that the transfer material is supplied from the transfer conveyance unit 2 to the image forming unit 3 via the registration roller 12. In the image forming unit 3, the electrophotographic units 15 a, 15 b, 15 c and 15 d, the transfer conveyance belt unit 22 and the transfer belt cleaning unit 24 are operated based on the detection result of the sensor 14.

  The electrophotographic unit 15a includes a photoconductor 16a that forms an electrostatic latent image on the surface thereof, a charger 17a that charges the surface of the photoconductor 16a, and light on the surface of the photoconductor 16a that is charged based on image information. , An exposure unit 18a for forming an electrostatic latent image by irradiating the toner, and a developing device 19a for forming a toner image by attaching toner to the electrostatic latent image on the surface of the photosensitive member 16a. The image forming apparatus includes a transfer roller 20a that transfers a toner image on the surface of the body 16a to a transfer material, and a cleaner unit 21a that removes toner remaining on the surface of the photoconductor 16a. The photoreceptor 16a is disposed (attached) at substantially the center of the image forming apparatus 100. Although the charger 17a is a charger-type charger, a contact-type roller-type or brush-type charger can be used. The exposure unit 18a is a unit that exposes the surface of the photoconductor 16a and forms an electrostatic latent image on the surface of the photoconductor 16a according to a black color component image of image data input from the outside. An EL writing head in which light emitting elements are arranged in an array, an LED writing head, a laser scanning unit (LSU) including a laser irradiation unit, and a reflection mirror are used. The developing device 19a is filled with black toner and develops the electrostatic latent image formed on the surface of the photoreceptor 16a as a black toner image. The transfer roller 20a is provided so as to press-contact the photoconductor 16a and the transfer belt 23 and to be rotatable in a direction opposite to the photoconductor 16a. Further, in order to transfer the toner image onto the transfer material, a high-voltage transfer bias having a polarity (+) opposite to the toner charging polarity (−) is applied to the transfer roller 20a. Therefore, when the transfer material passes between the photoconductor 16a and the transfer roller 20a, the black toner image on the surface of the photoconductor 16a is transferred to the transfer material. As the transfer roller 20a, for example, a surface of a metal shaft made of a metal such as stainless steel having a diameter of 8 to 10 mm is coated with a conductive elastic material such as EPDM or urethane foam. The conductive elastic material as described above can uniformly apply a high voltage to the transfer material. A brush may be used in place of the transfer roller 20a. The cleaner unit 21a removes and collects the black toner remaining on the surface of the photoreceptor 16a after the black toner image is transferred.

  The electrophotographic units 15b, 15c, and 15d respectively provide electrostatic latent images corresponding to the cyan, magenta, and yellow component images of the image information input from the outside to the photosensitive members 16b, 16c, and 16d. The electrophotographic unit 15a has the same configuration as the electrophotographic unit 15a except that a cyan toner image, a magenta toner image, and a yellow image are formed. Accordingly, the same reference numerals are used except that the alphabetic suffixes attached to the reference numerals are changed to b (cyan), c (magenta), or d (yellow), and description thereof is omitted.

  The transfer conveyance belt unit 22 is provided so as to be in contact with the photosensitive members 16a, 16b, 16c, and 16d, conveys the transfer material, and transfers the toner images of the respective colors onto the transfer material by the electrophotographic units 15a, 15b, 15c, and 15d. The transfer belt 23, a transfer belt drive roller 25 that rotates the transfer belt 23 in the direction of an arrow 29, transfer belt driven rollers 26 and 28 that assist in driving the transfer belt 23, and a predetermined tensile force applied to the transfer belt 23 And a transfer belt tension roller 27 for imparting toner. The transfer belt 23 is stretched by rollers 25, 26, 27, and 28, and is driven to rotate stably in the direction of the arrow 29, and sequentially transfers the transfer material to the electrophotographic photosensitive units 15a, 15b, 15c, and 15d. A toner image of each color is formed on the transfer material and fed to the fixing unit 30. The transfer belt 23 is formed endlessly using a film having a thickness of about 100 to 150 μm.

  The transfer belt cleaning unit 24 removes the toner because the toner adhering to the transfer belt 23 due to contact with the photosensitive drums 16a, 16b16c, and 16d causes the back surface (non-image forming surface) of the transfer material to become dirty. Provided for recovery. The transfer belt cleaning unit 24 is provided in contact with the transfer belt 23 and is supported by a transfer belt driven roller 28 from the back side of the transfer belt 23. For example, the transfer belt cleaning unit 24 includes a cleaning blade as a cleaning member.

  The transfer material discharge section 4 is provided outside the side surface of the apparatus 100, and is discharged to the outside of the apparatus 100 via the transfer material conveyance path 6a. The discharge tray 34 holds the transfer material on which an image is formed. A side cover 35 provided to eliminate clogging of the transfer material in the transfer material conveyance paths 6, 6 a and the outside of the upper surface of the apparatus 100 are discharged to the outside of the apparatus 100 via the transfer conveyance path 6. And a paper discharge tray 37 for holding a transfer material on which an image is formed. A paper discharge tray 34 provided on the side of the image forming apparatus 100 is a tray for placing the image-formed transfer material face up. A paper discharge tray 37 provided outside the upper surface of the image forming apparatus 100 is a tray for placing an image-formed transfer material face down.

  For example, the control unit 5 feeds the image forming unit 3 of the transfer material by the registration roller 12, forms a toner image on the transfer material, rotationally drives the transfer conveyance unit 23, operates the fixing unit 30, and transfers after image formation. Various functions in the image forming apparatus 100 such as discharge of the material to the trays 34 and 37 are controlled.

  In the image forming apparatus 100, the transfer material supplied from the paper feed tray 10 is conveyed through the transfer material conveyance path 6, and the image forming unit 3 forms electrophotographic units 15 a, 15 b, 15 c, A multi-color toner image is formed by 15d, and the toner image is fixed on the transfer material by the fixing unit 30, and then discharged to the tray 34 or the tray 37.

  The present invention will be specifically described below with reference to production examples, examples and comparative examples. In the following, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively, unless otherwise specified.

  The solid content, polar group amount, polar group amount after melt-kneading, weight average molecular weight and glass transition point of the pigment surface treatment agent having a thermally decomposable polar group obtained in Production Example were measured as follows.

(A) Solid content The weight of the pigment surface treatment agent before and after the heat treatment at 105 ° C. for 3 hours was measured, and the percentage of the weight after the heat treatment relative to the weight before the heat treatment was determined.

(B) Polar group amount 1.0 g of a pigment surface treating agent having a thermally decomposable polar group was dissolved in 50 ml of tetrahydrofuran, and this solution was adjusted to 0 using an automatic titrator (AT-510: manufactured by Kyoto Electronics Industry Co., Ltd.). 1N hydrochloric acid ethanol solution was titrated and potentiometric titration was performed. The amount of hydrochloric acid (mg) used for neutralization was converted to KOH mg, converted to solid content, and the amount of polar group per gram of pigment surface treatment agent having a thermally decomposable polar group was calculated.

(C) Polar group amount in terms of toner Neutralization was carried out in the same manner as in (B) except that 1.0 g of the toner obtained instead of the pigment surface treatment agent having a thermally decomposable polar group was used. The amount of hydrochloric acid (mg) was converted to KOH mg, and the amount of polar group per gram of toner was calculated.

(D) Weight average molecular weight (MW)
The weight average molecular weight in terms of polystyrene of the pigment surface treatment agent having a thermally decomposable polar group was determined by gel permeation chromatography (GPC). Equipment used and conditions are as follows. The molecular weight calibration curve was prepared using standard polystyrene.
Apparatus: SYSTEM-11 (trade name, manufactured by Showa Denko KK)
Column: 3 TSKgelαMXL (trade name, manufactured by Tosoh Corporation) Measurement temperature: 40 ° C.
Sample solution: 0.10% dimethylformamide solution of pigment surface treatment agent having thermally decomposable polar group Injection amount: 100 ml
Detector: Refractive index detector

(E) Glass transition point After heating the pigment surface treatment agent having a thermally decomposable polar group at 105 ° C for 3 hours, a second is used using a differential scanning calorimeter (trade name: DSC-50, manufactured by Shimadzu Corporation). According to the run method, it measured with the temperature increase rate of 10 degree-C / min.

(Production Example 1)
100 parts by weight of toluene was charged into a 300 ml separable flask equipped with a stirrer, a thermometer, a nitrogen inlet and a condenser. The mixture was heated under a nitrogen atmosphere to maintain the temperature of the internal space of the separable flask at 90 ° C., and a mixture of the following monomer and radical polymerization initiator was added dropwise over 3 hours.
Styrene 70 parts n-butyl acrylate 14 parts 2-ethylhexyl acrylate 10 parts glycidyl methacrylate 6 parts radical polymerization initiator 1.0 part (trade name: V-601, manufactured by Wako Pure Chemical Industries, Ltd.)
0.1 parts of radical polymerization initiator (V-601) was further added to the reaction solution, and reacted for 5 hours. A pigment surface treating agent R having a thermally decomposable polar group is obtained by adding 5.0 parts of N-methyldiethanolamine and 2.5 parts of acetic acid to the resulting molten resin and reacting at 70 ° C. for 2 hours to perform quaternization. -1 was obtained. The obtained pigment surface treating agent R-1 had a solid content of 53%, a polar group concentration of 23.5 KOHmg / g, a weight average molecular weight of 18500, and a glass transition point of 64 ° C.

(Production Example 2)
100 parts by weight of toluene was charged into a 300 ml separable flask equipped with a stirrer, a thermometer, a nitrogen inlet and a condenser. The mixture was heated under a nitrogen atmosphere to maintain the temperature of the internal space of the separable flask at 90 ° C., and a mixture of the following monomer and radical polymerization initiator was added dropwise over 3 hours.
Styrene 60 parts Polypropylene glycol monomethacrylate 20 parts (Brand name: BLEMMER PP800: manufactured by NOF Corporation)
Methyl methacrylate 5 parts Glycidyl methacrylate 15 parts Radical polymerization initiator (V-601) 0.8 part The reaction solution was further added with 0.1 parts by weight of a radical polymerization initiator (V-601) and allowed to react for 5 hours. In the molten resin thus produced, 18.8 parts of 1- (2-hydroxyethylthio) -2-propanol (trade name: SHP-100, manufactured by Sanyo Chemical Industries, Ltd.), 6.3 parts of acetic acid and deionized water 15.2 parts were added and reacted at 65 ° C. for 5 hours to obtain a pigment surface treating agent R-2 having a thermally decomposable polar group. The obtained pigment surface treating agent R-2 had a solid content of 51%, a polar group concentration of 25.6 mgKOH / g, a weight average molecular weight of 23500, and a glass transition point of 57 ° C. The thermally decomposable polar group is a sulfonium base, R ¹ and R ² are each a group —CH ₂ CH ₂ OH or a group —CH ₂ CH (CH ₂ ) OH, and R ³ is a group —CH ₃ . The anion is COO ⁻ .

(Production Example 3)
A pigment surface treatment agent having a thermally decomposable polar group in the same manner as in Example 2 except that the amount of toluene used is 90 parts, the amount of radical polymerization initiator used is 0.7 parts, and the polymerization temperature is changed to 85 ° C. R-3 was obtained. Pigment surface treating agent R-3 had a solid content of 55%, a polar group concentration of 24.9 mgKOH / g, a weight average molecular weight of 28900, and a glass transition point of 58 ° C.

(Production Example 4)
Pigment surface treatment agent having a thermally decomposable polar group in the same manner as in Example 2 except that the amount of toluene used is 120 parts, the amount of radical polymerization initiator used is 3.5 parts, and the polymerization temperature is changed to 110 ° C. R-4 was obtained. Pigment surface treating agent R-4 had a solid content of 46%, a polar group concentration of 24.2 mgKOH / g, a weight average molecular weight of 3900, and a glass transition point of 54 ° C.

(Production Example 5)
Pigment surface treating agent having a thermally decomposable polar group in the same manner as in Example 2 except that the amount of toluene used is 135 parts, the amount of radical polymerization initiator used is 5.0 parts, and the polymerization temperature is changed to 110 ° C. R-5 was obtained. Pigment surface treating agent R-5 had a solid content of 42%, a polar group concentration of 24.6 mgKOH / g, a weight average molecular weight of 2400, and a glass transition point of 52 ° C.

(Production Example 6)
In a separable flask equipped with a stirrer, a thermometer, a nitrogen inlet, and a cooling tube, 246 g of cresol novolac type epoxy resin (trade name: YDCN-703, manufactured by Tohto Kasei Co., Ltd., epoxy equivalent: 205 g / equivalent), flaxseed 121 g of oil fatty acid, 9 g of hydroquinone and 37 g of toluene were added, and the temperature was raised to 80 ° C. in a nitrogen atmosphere to dissolve the epoxy resin. The temperature was further raised to 100 ° C. and 0.2 g of tetrabutylammonium bromide was added, and the temperature was adjusted to 100 The reaction was carried out while maintaining at 0 ° C. During the reaction, the remaining amount of epoxy groups was measured at regular intervals, and when the epoxy equivalent reached 620 (g / equivalent) in about 4 hours, SHP-100 (manufactured by Sanyo Chemical Industries, Ltd.) while cooling down. 81.6 g, 36.0 g acetic acid and 86.4 g deionized water were added and stirring was continued at 75 ° C. The amount of sulfonium group, which is a hydrated functional group, was measured at regular intervals, and since no increase in the amount of sulfonium group was observed in about 6 hours, the reaction was stopped by adding 72 g of deionized water, and the thermally decomposable polar group Pigment surface treating agent R-6 having The obtained pigment surface treating agent R-6 had a solid content of 65.0%, a polar group concentration of 48.2 mgKOH / g, a weight average molecular weight of 13500, and a glass transition point of 59 ° C. The thermally decomposable polar group is a sulfonium base, R ¹ and R ² are each a group —CH ₂ CH ₂ OH or a group —CH ₂ CH (CH ₂ ) OH, and R ³ is a group —CH ₃ . The anion is COO ⁻ . The sulfonium base was bound to the epoxy resin via the group —O—CH (OH) CH ₂ —.

(Production Example 7)
A pigment surface treating agent R-7 having a thermally decomposable polar group was obtained in the same manner as in Production Example 6 except that the amount of linseed oil fatty acid was changed to 62 g. The obtained pigment surface treating agent R-7 had a solid content of 66.0%, a polar group concentration of 47.3 mgKOH / g, a weight average molecular weight of 15200, and a glass transition point of 61 ° C.

(Production Example 8)
A pigment surface treating agent R-8 having a thermally decomposable polar group was obtained in the same manner as in Production Example 6 except that 57.6 g of methanesulfonic acid was used instead of 36.0 g of acetic acid. The obtained pigment surface treating agent R-8 had a solid content of 64.0%, a polar group concentration of 58.2 mgKOH / g, a weight average molecular weight of 14400, and a glass transition point of 61 ° C. The thermally decomposable polar group is a sulfonium base, R ¹ and R ² are each a group —CH ₂ CH ₂ OH or a group —CH ₂ CH (CH ₂ ) OH, and R ³ is a group —CH ₃ . Anion is SO ₃ ^- is. The sulfonium base was bound to the epoxy resin via the group —O—CH (OH) CH ₂ —.

  The amount of the thermally decomposable polar group, the kind and weight average molecular weight of the thermally decomposable polar group, and the grafting of the pigment surface treatment agents R-1 to R-8 having the thermally decomposable polar group obtained in Production Examples 1-8 The presence or absence is shown in Table 1.

  In the item of presence / absence of grafting, “◯” means grafted and “−” means not grafted.

(Production Example 9)
Pigment surface treatment agent R-1 to R-5 having pyrolyzable polar group 250 parts (solid content), acid-treated phthalocyanine pigment 500 parts, linear polyester resin (MW = 21500, Tg = 59 ° C.) 125 parts, charge control 25 parts of an agent (trade name: Bontron E-84, manufactured by Orient Chemical Co., Ltd.) and 150 parts of polypropylene wax were uniformly mixed, and then kneaded at 140 ° C. with a biaxial extruder to obtain a master having a pigment concentration of 50%. Batches M-1 to M-5 were obtained.

  Master batch M-6 was obtained in the same manner as described above except that pigment surface treating agent R-2 having a thermally decomposable polar group was used and that an untreated phthalocyanine pigment was used instead of an acid-treated phthalocyanine pigment.

(Example 1)
500 parts of master batch M-1 and 2000 parts of linear polyester resin (MW = 21500, Tg = 59 ° C.) were uniformly mixed, and then kneaded for 1 hour in a biaxial open roll machine having an internal temperature of 250 ° C. The obtained kneaded material was cooled and solidified, finely pulverized with a jet mill, and classified with a dispersion separator to obtain a toner powder having an average particle diameter of 6 μm. The amount of the thermally decomposable polar group remaining in the toner was 0.93 mgKOH /.

  The toner powder of Example 1 was obtained by mixing 100 parts of this toner powder and 1.0 part of hydrophobic silica fine powder (trade name: RX-200, manufactured by Nippon Aerosil Co., Ltd.).

(Comparative Example 1)
A toner of Comparative Example 1 was obtained in the same manner as in Example 1 except that the internal temperature of the biaxial open roll machine was changed to 160 ° C. The residual polar group amount in terms of toner in the pigment surface treatment agent remaining in the toner was 1.17 mg KOH / g.

(Example 2)
A toner of Example 2 was obtained in the same manner as in Example 1 except that the master batch was changed to M-2 and the internal temperature of the biaxial open roll machine was changed to 150 ° C. The residual polar group amount in terms of toner in this toner was 0.78 mg KOH / g.

(Example 3)
A toner of Example 3 was obtained in the same manner as in Example 2 except that the internal temperature of the biaxial open roll machine was changed to 165 ° C. The residual polar group amount in terms of toner in this toner was 0.43 mg KOH / g.

Example 4
A toner of Example 4 was obtained in the same manner as in Example 2 except that the internal temperature of the biaxial open roll machine was changed to 180 ° C. The residual polar group amount in terms of toner in this toner was 0.09 mg KOH / g.

(Example 5)
A toner of Example 5 was obtained in the same manner as in Example 2 except that the internal temperature of the biaxial open roll machine was changed to 200 ° C. The residual polar group amount in terms of toner in this toner was 0.03 mg KOH / g.

(Example 6)
A toner of Example 6 was obtained in the same manner as in Example 1 except that the master batch was changed to M-3 and the internal temperature of the biaxial open roll machine was changed to 160 ° C. The residual polar group amount in terms of toner in this toner was 0.34 mgKOH / g.

(Example 7)
A toner of Example 7 was obtained in the same manner as in Example 6 except that the master batch was changed to M-4. The residual polar group amount in terms of toner in this toner was 0.36 mg KOH / g.

(Example 8)
A toner of Example 8 was obtained in the same manner as in Example 6 except that the master batch was changed to M-5. The residual polar group amount in terms of toner in this toner was 1 mgKOH / g.

Example 9
A toner of Example 9 was obtained in the same manner as in Example 6 except that the master batch was changed to M-6. The residual polar group amount in terms of toner in this toner was 0.41 mgKOH / g.

(Example 10)
250 parts (solid content) of pigment surface treatment agent R-6 having a thermally decomposable polar group, 500 parts of acid-treated quinacidone pigment, 4075 parts of linear polyester resin (MW = 21500, Tg = 59 ° C.) and a charge control agent (Bontron E) -84) After 25 parts and 150 parts of polypropylene wax were uniformly mixed, the mixture was kneaded for 90 minutes in a biaxial open roll machine with an internal temperature of 165 ° C, and then the cooled product was finely pulverized with a jet mill, and a dispersion separator To obtain a powder having an average particle size of 6 μm. The residual polar group amount in terms of toner of this toner was 0.39 mg KOH / g. To 100 parts of this powder, 1.0 part of hydrophobic silica fine powder (BET specific surface area 120 m ^{2 /} g) surface-treated with a silane coupling agent and dimethyl silicone oil was mixed to obtain a toner of Example 10. .

(Comparative Example 2)
A toner of Comparative Example 2 was obtained in the same manner as in Example 10 except that the kneading time of the open roll was changed to 30 minutes. The residual polar group amount in terms of toner in this toner was 1.34 mg KOH / g.

(Example 11)
A toner of Example 11 was obtained in the same manner as in Example 10, except that the amount of the pigment surface treatment agent R-6 having a thermally decomposable polar group was changed to 450 parts (solid content). The residual polar group amount in terms of toner in this toner was 0.69 mgKOH / g.

(Comparative Example 3)
A toner of Comparative Example 3 was obtained in the same manner as in Example 10 except that the amount of the pigment surface treating agent R-6 having a thermally decomposable polar group was changed to 650 parts (solid content). The residual polar group amount in terms of toner in this toner was 1.67 mg KOH / g.

(Example 12)
A toner of Example 12 was obtained in the same manner as in Example 10, except that the amount of the pigment surface treating agent R-6 having a thermally decomposable polar group was changed to 150 parts (solid content). The residual polar group amount in terms of toner in this toner was 0.40 mgKOH / g.

(Example 13)
A toner of Example 13 was obtained in the same manner as in Example 10, except that the amount of the pigment surface treating agent R-6 having a thermally decomposable polar group was changed to 75 parts (solid content). The residual polar group amount in terms of toner in this toner was 0.22 mg KOH / g.

(Example 14)
The toner of Example 14 was obtained in the same manner as in Example 10, except that the acid-treated quinacridone pigment concentration in the toner was changed to 6.5% and the pigment surface treating agent R-6 concentration was changed to 0.5%. The residual polar group amount in terms of toner in this toner was 0.35 mgKOH / g.

(Example 15)
A toner of Example 15 was obtained in the same manner as in Example 10, except that the acid-treated quinacridone pigment concentration in the toner was changed to 5.0% and the pigment surface treating agent R-6 concentration was changed to 0.8%. The residual polar group amount in terms of toner in this toner was 0.51 mgKOH / g.

(Example 16)
The toner of Example 16 was obtained in the same manner as in Example 10, except that the acid-treated quinacridone pigment concentration in the toner was changed to 14.5% and the pigment surface treating agent R-6 concentration was changed to 0.4%. The residual polar group amount in terms of toner in this toner was 0.59 mgKOH / g.

(Example 17)
A toner of Example 17 was obtained in the same manner as in Example 10, except that the acid-treated quinacridone pigment concentration in the toner was changed to 16.5% and the pigment surface treating agent R-6 concentration was changed to 0.3%. The residual polar group amount in terms of toner in this toner was 0.56 mgKOH / g.

(Example 18)
A toner of Example 18 was obtained in the same manner as in Example 10, except that the pigment surface treating agent having a thermally decomposable polar group was changed to R-7. The residual polar group amount in terms of toner in this toner was 0.67 mgKOH / g.

(Comparative Example 4)
A toner of Comparative Example 4 was obtained in the same manner as in Example 10 except that the pigment surface treating agent having a thermally decomposable polar group was changed to R-8. The residual polar group amount in terms of toner in this toner was 2.9 mgKOH / g.

(Comparative Example 5)
A toner of Comparative Example 5 was obtained in the same manner as in Example 10 except that the pigment surface treating agent R-6 was not used.

(Test Example 1)
An image was formed on the transfer material using the color toners of Examples 1 to 18 and Comparative Examples 1 to 4, and (a) coloring power, (b) saturation, (c) transparency, and (d) The charging stability was evaluated as follows.

  For Examples 1 to 18 and Comparative Examples 1 to 4, evaluation was performed for each primary color of cyan and magenta, and for Example 19, the toners of Example 3 and Example 10 were overlaid. The secondary color was evaluated.

(A) Coloring power:
Full-color exclusive paper (trade name: PP106A4C, Sharp) by adjusting the toner adhesion amount to 0.50 mg / cm ² with a copier (trade name: AR-C260S, manufactured by Sharp Corporation) having a one-component development system. An unfixed image was formed on the product, and the formed unfixed image was fixed by an external fixing machine.

  About the obtained image, image density was measured using the Macbeth reflection densitometer (brand name: RD-918, product made by Macbeth). A case where the image density was 1.5 or more was judged good, a case where the image density was 1.6 or more was judged good, and a case where the image density was less than 1.5 was judged bad.

(B) Saturation:
(A) L * a * b * color system (CIE 1976) with respect to an image obtained in the same manner as in the evaluation of tinting strength using a spectrocolorimeter (trade name: X-Rite, manufactured by Nippon Flat Printing Equipment Co., Ltd.) The values of the chromaticness indices a * and b * in (CIE: Commission Internationaledel 'Eclairage: International Lighting Commission) were determined, and the saturation C * was calculated based on the following formula. Saturation C * was used as an index of color reproducibility. A case where the saturation C * was 75 or more was judged as good, and a case where the saturation C * was less than 75 was judged as bad.
C * = (a * × 2 + b * × 2) ^1/2

(C) Transparency:
(A) Evaluation of tinting strength, except that the toner adhesion amount is adjusted so that the image density is 1.7, and an OHP dedicated sheet (trade name: CX-7A4C, manufactured by Sharp Corporation) is used as a transfer material. An image was formed in the same manner.

About this image, HGM-2DP (made by Suga Test Instruments Co., Ltd.) for direct reading haze computer C light sources was used, the diffuse transmitted light amount and the total transmitted light amount were measured, and haze value was computed. The haze value is an index representing the degree to which light rays that have passed through a transparent sample diffuse. The diffuse transmitted light amount is the amount of light that diffuses out of the light rays that have passed through the sample when parallel light rays are incident on the sample, and the total transmitted light amount is the total amount of light that has passed through the sample (diffused light and parallel light rays). . When the diffuse transmitted light amount is Td and the total transmitted light amount is Tt, the haze value is expressed by the following equation.
Haze value (%) = (Td / Tt) × 100

  The smaller the haze value, the smaller the amount of diffuse transmitted light and the higher the transparency. The case was regarded as defective because of lack of practicality.

(D) Charging stability:
A printing test was conducted in an environment of an air temperature of 30 ° C. and a humidity of 80% (HH) and an air temperature of 10 ° C. and a humidity of 20% (LL), and the image density of the solid portion after printing 10,000 sheets was measured with a Macbeth reflection densitometer (RD-918: Measurement was performed using Macbeth Co.). An HH / LL image density ratio of 0.80 or more was judged good, 0.90 or more was judged good, and less than 0.80 was regarded as impractical.
The results are shown in Table 2.

  From Table 2, the color toner according to the present invention has excellent characteristics such as coloring power, color reproducibility (saturation), transparency (light transmission), and main characteristics required for the toner at a high level. It turns out that it is a toner.

1 is a cross-sectional view schematically showing a configuration of an image forming apparatus to which a color toner of the present invention can be applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper feed part 2 Transfer material conveyance part 3 Image formation part 4 Transfer material discharge part 5 Control part 6, 6a Transfer material conveyance path 10 Paper feed tray 11 Pickup roller 12 Registration roller 13 Illumination 14 Sensor 15a, 15b, 15c, 15d Electron Photo unit 16a, 16b, 16c, 16d Photoconductor 17a Charger 18a Exposure unit 19a Developer 20a Transfer roller 21a Cleaner unit 22 Transfer conveyance belt unit 23 Transfer belt 24 Transfer belt cleaning unit 25 Transfer belt drive roller 26, 28 Transfer belt driven Roller 27 Transfer belt tension roller 29 Arrow 30 Fixing unit 31 Heat roller 32 Pressure roller 33 Transport direction switching guide 33a Guide shaft 33b Guides 34, 37 Paper discharge tray 35 Side cover 36 Transport roller 00 image forming apparatus

Claims (7)

  In a color toner for developing an electrostatic latent image containing at least a binder resin and a pigment, a pigment surface treatment agent having a thermally decomposable polar group adheres to part or all of the pigment surface, and the thermally decomposable polar group per 1 g of the toner A color toner for developing an electrostatic latent image, wherein the content is 1.0 KOHmg or less.   The color toner for developing an electrostatic latent image according to claim 1, wherein the pigment surface treating agent having a thermally decomposable polar group is a synthetic resin having a thermally decomposable polar group.   The color toner for developing an electrostatic latent image according to claim 1 or 2, wherein the pigment surface treatment agent having a thermally decomposable polar group is an acrylic resin or an epoxy resin having a thermally decomposable polar group. Thermally decomposable polar group is a general formula

[Wherein, R ¹ and R ² are the same or different and each represents an alkyl group having 1 to 6 carbon atoms, an alkanol group having 1 to 6 carbon atoms, a phenyl group, or a hydroxyphenyl group. R ³ represents an alkyl group having 1 to 4 carbon atoms, an alkanol group having 1 to 4 carbon atoms, a phenyl group, or a hydroxyphenyl group. ]
The color toner for developing an electrostatic latent image according to claim 1, wherein the toner is a sulfonium base represented by the formula:   The electrostatic latent image according to any one of claims 1 to 4, wherein a monomer containing an alkyl group having 12 or more carbon atoms is further graft-polymerized on the pigment surface treatment agent having a thermally decomposable polar group. Color toner for development.   The color toner for developing an electrostatic latent image according to any one of claims 1 to 5, wherein the pigment surface treating agent having a thermally decomposable polar group has a weight average molecular weight of 3000 or more and 25000 or less.   The color toner for developing an electrostatic latent image according to any one of claims 1 to 6, wherein the pigment is a pigment whose surface is modified to be acidic.

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