JP6854234B2 - Xerographic toner - Google Patents

Description

The present invention relates to, for example, an electrophotographic toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

Patent Document 1 describes a toner containing a binder resin and a colorant, wherein the colorant is CI Pigment Red 53: 1, 53: 3, 31, 146, 147, 150, 170, 175, 176, 185, A red toner characterized by containing one or more pigments selected from 187, 188 and 269 and CI Pigment Red 48: 1 is disclosed.

Patent Document 2 describes a toner containing a binder resin, a colorant, a mold release agent, and a charge control agent, wherein the binder resin contains resin H and resin L having different softening points. The resin H is a non-linear polyester having a softening point of 140 ° C. or higher and 170 ° C. or lower, and the resin L is a linear polyester having a softening point of 85 ° C. or higher and 95 ° C. or lower and a peak top molecular weight of 6000 or higher and 8000 ° C. or lower. It is a polyester, the mass ratio of the resin H to the resin L (resin H / resin L) is 50/50 to 80/20, and the mold release agent contains 95 mol of α-olefin having 26 or more and 28 or less carbon atoms. Contains an α-olefin polymer obtained by polymerizing a monomer containing% or more, and the content of the α-olefin polymer is 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the binder resin. The toner is disclosed.

Japanese Unexamined Patent Publication No. 2004-117649 Japanese Unexamined Patent Publication No. 2015-114649

Although CIPigment Red 188 is not often used as a colorant for toner, it has a color closer to vermilion than ordinary red pigments, and toners with such a color may be desired.
However, when CIPigment Red 188 is used, fog is likely to occur due to insufficient charging at the initial stage of printing due to the deterioration of toner charging stability, and the fine line reproducibility, which is thought to be caused by overcharging, occurs after printing. It tends to be easy, especially when the amount used is large.

The present invention relates to an electrophotographic toner having excellent fog suppression at the initial stage of printing and fine line reproducibility after printing resistance.

The present invention is an electrophotographic toner containing a binder resin, a colorant, and a charge control agent, wherein the binder resin is a carboxylic acid containing an alcohol component and an aliphatic dicarboxylic acid compound in an amount of 60 mol% or more. The polyester resin A, which is a polycondensate with an acid component, is contained in an amount of 50% by mass or more, and the coloring agent contains 5 parts by mass or more of CI Pigment Red 188 with respect to 100 parts by mass of the binder resin. The present invention relates to an electrophotographic toner in which a control agent contains a metal compound of a benzylic acid compound.

The toner for electrophotographic of the present invention exerts excellent effects in suppressing fog at the initial stage of printing and reproducibility of fine lines after printing resistance.

The electrophotographic toner of the present invention (hereinafter, also simply referred to as toner) uses a polyester resin using an aliphatic dicarboxylic acid compound as a binder resin and a predetermined amount of CI Pigment Red 188 as a colorant as a charge control agent. Each of them contains a metal compound of a benzylic acid compound, and in the present invention, by combining these, the fog suppression at the initial stage of printing and the fine line reproducibility after printing resistance, which are the problems of the toner containing CIPigment Red 188, are improved. be able to.
Although the detailed mechanism is unknown, in the initial printing, the effect of the charge control agent, which is a boron complex having a good charge rise property, is effective, and the aliphatic dicarboxylic acid compound having no aromatic ring after printing resistance. It is presumed that overcharging can be suppressed and the fine line reproducibility can be stabilized by allowing the part derived from the above to leak the charge moderately.

In the present invention, the binder resin contains a polyester resin A which is a polycondensate of an alcohol component and a carboxylic acid component containing an aliphatic dicarboxylic acid compound.

Examples of the aliphatic dicarboxylic acid compound include fumaric acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, anhydrides of these acids, and alkyl esters having 1 or more and 3 or less carbon atoms thereof. Among these, from the viewpoint of fine line reproducibility after printing resistance, an aliphatic dicarboxylic acid compound having 3 or more and 6 or less carbon atoms is preferable, and fumaric acid or maleic acid is more preferable. The carbon number of the alkyl group in the alkyl ester portion is not included in the above carbon number.

The content of the aliphatic dicarboxylic acid compound is 60 mol% or more, preferably 65 mol% or more, more preferably 70 mol% or more, and 100 mol% or less, and is resistant to the carboxylic acid component. From the viewpoint of fine line reproducibility after printing, it is preferably 95 mol% or less, more preferably 90 mol% or less.

Examples of the carboxylic acid component other than the aliphatic dicarboxylic acid compound include aromatic dicarboxylic acid compounds such as phthalic acid, isophthalic acid and terephthalic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; trimellitic acid, 2,5, Examples thereof include trivalent or higher aromatic carboxylic acids such as 7-naphthalene tricarboxylic acid and pyromellitic acid, anhydrides thereof, and alkyl esters having 1 or more and 3 or less carbon atoms.

The content of the trivalent or higher aromatic carboxylic acid compound is preferably 10 mol% or more, more preferably 20 mol% or more, still more preferably 20 mol% or more, from the viewpoint of increasing the viscosity of the toner and maintaining the high temperature offset resistance. It is 25 mol% or more, and from the viewpoint of low temperature fixability, it is preferably 50 mol% or less, more preferably 40 mol% or less, still more preferably 35 mol% or less.

As the alcohol component, the formula (I): is used from the viewpoint of achieving both low temperature fixability, durability and storage stability.

(In the formula, OR and RO are oxyalkylene groups, R is ethylene and / or propylene group, x and y indicate the average number of moles of alkylene oxide added, which are positive numbers, respectively, of x and y. The value of the sum is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, still more preferably 4 or less).
It is preferable to contain an alkylene oxide adduct of bisphenol A represented by. Examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include a polyoxypropylene adduct of 2,2-bis (4-hydroxyphenyl) propane and 2,2-bis (4-hydroxyphenyl) propane. Examples include polyoxyethylene adducts. It is preferable to use one or more of these.

The content of the alkylene oxide adduct of bisphenol A represented by the formula (I) is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 90 mol% or more in the alcohol component. It is 95 mol% or more, more preferably 100 mol%.

Other alcohol components include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,4-butene. Examples thereof include aliphatic diols such as diols, 1,3-butanediol and neopentyl glycol, and trihydric or higher alcohols such as glycerin.

A monohydric alcohol may be appropriately contained in the alcohol component, and a monovalent carboxylic acid compound may be appropriately contained in the carboxylic acid component.

The equivalent ratio of the carboxylic acid component to the alcohol component (COOH group / OH group) is preferably 0.6 or more, more preferably 0.7 or more, still more preferably 0.75 or more, and more preferably 0.75 or more, from the viewpoint of adjusting the softening point of the polyester resin. , Preferably 1.1 or less, more preferably 1.05 or less.

The polyester resin A preferably contains, for example, an alcohol component and a carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and if necessary, in the presence of an esterification co-catalyst, a polymerization inhibitor, or the like. Can be produced by polycondensation at a temperature of 130 ° C. or higher, more preferably 170 ° C. or higher, and preferably 250 ° C. or lower, more preferably 240 ° C. or lower.

Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropyrate bistriethanolaminate, and tin compounds are preferable. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. It is preferably 1 part by mass or less. Examples of the esterification co-catalyst include gallic acid and the like. The amount of the esterification co-catalyst used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. More preferably, it is 0.1 parts by mass or less. Examples of the polymerization inhibitor include t-butylcatechol and the like. The amount of the polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. It is preferably 0.1 parts by mass or less.

In the present invention, the polyester resin may be a polyester resin modified to such an extent that its characteristics are not substantially impaired. Examples of the modified polyester resin include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636 and the like. Examples of the modified polyester resin include a modified polyester resin, and among the modified polyester resins, a urethane-modified polyester resin obtained by urethane-extending the polyester resin with a polyisocyanate compound is preferable.

The softening point of the polyester resin A is preferably 130 ° C. or higher, more preferably 140 ° C. or higher, still more preferably 150 ° C. or higher from the viewpoint of storage stability, and preferably 180 ° C. or higher from the viewpoint of low temperature fixability. Below, it is more preferably 170 ° C. or lower, still more preferably 165 ° C. or lower.

The glass transition temperature of the polyester resin A is preferably 40 ° C. or higher, more preferably 50 ° C. or higher from the viewpoint of storage stability, and preferably 80 ° C. or lower, more preferably 70 ° C. or higher from the viewpoint of low temperature fixability. It is below ° C.

The acid value of the polyester resin A is preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, still more preferably 25 mgKOH / g or more, and in a high temperature and high humidity environment, from the viewpoint of initial charge rising property. From the viewpoint of charge stability, it is preferably 50 mgKOH / g or less, more preferably 45 mgKOH / g or less, and further preferably 40 mgKOH / g or less.

The content of the polyester resin A is 50% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more in the binder resin from the viewpoint of fine line reproducibility after printing resistance.

The toner of the present invention preferably contains a polyester resin B having a softening point lower than that of the polyester resin A as the binder resin.

Examples of the alcohol component and the carboxylic acid component of the polyester resin B include those similar to those of the polyester resin A, but the carboxylic acid component preferably contains an aromatic dicarboxylic acid-based compound, and the content thereof is carboxylic acid. Among the components, preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, still more preferably 100 mol%. ..

The difference in softening points between the polyester resin A and the polyester resin B is preferably 15 ° C. or higher, more preferably 20 ° C. or higher, and melts during toner production, from the viewpoint of achieving both low-temperature fixability and high-temperature offset resistance. From the viewpoint of improving the dispersibility of the pigment in kneading and the dispersibility of the charge control agent, the temperature is preferably 60 ° C. or lower, more preferably 55 ° C. or lower.

The softening point of the polyester resin B is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, still more preferably 90 ° C. or higher from the viewpoint of storage stability, and preferably 130 ° C. or higher from the viewpoint of low temperature fixability. Below, it is more preferably 120 ° C. or lower, still more preferably 115 ° C. or lower.

The glass transition temperature of the polyester resin B is preferably 40 ° C. or higher, more preferably 50 ° C. or higher from the viewpoint of storage stability, and preferably 80 ° C. or lower, more preferably 70 ° C. or higher from the viewpoint of low temperature fixability. It is below ° C.

The acid value of the polyester resin B is preferably 3 mgKOH / g or more from the viewpoint of initial charge rising property, and preferably 30 mgKOH / g or less from the viewpoint of charge stability in a high temperature and high humidity environment. Is 20 mgKOH / g or less, more preferably 10 mgKOH / g or less.

The mass ratio of the polyester resin A to the polyester resin B (polyester resin A / polyester resin B) is preferably 40/60 or more, more preferably 50/50 or more, still more preferably 50/50 or more, from the viewpoint of fine line reproducibility after printing resistance. It is 60/40 or more, and from the viewpoint of low temperature fixability, it is preferably 90/10 or less, more preferably 85/15 or less, and further preferably 80/20 or less.

The total content of the polyester resin A and the polyester resin B is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 100% by mass in the binder resin.

Examples of the binder resin other than the polyester resin A and the polyester resin B include polystyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, and styrene. Styrene-based resin, epoxy-based resin, which is a copolymer or copolymer containing styrene or a styrene-substituted product such as a maleic acid copolymer, a styrene-acrylic acid ester copolymer, or a styrene-methacrylic acid ester copolymer. One or more selected from resins such as rosin-modified maleic acid resin, polyethylene resin, polypropylene resin, polyurethane resin, silicone resin, phenol resin, polyamide resin, aliphatic or alicyclic hydrocarbon resin. Can be mentioned.

In the present invention, the colorant contains C.I.Pigment Red 188.

The content of CIPigment Red 188 can be appropriately selected according to the color tone of the target toner, etc., but in the present invention, the content of CIPigment Red 188 alone is large enough to secure the image density as red toner. When CIPigment Red 188 is used, the effect of the present invention is more prominently exhibited. Therefore, the content of CIPigment Red 188 is 5 parts by mass or more, preferably 6 parts by mass or more, more preferably 7 parts by mass or more, and further preferably 9 parts by mass or more with respect to 100 parts by mass of the binder resin. From the viewpoint of suppressing fog at the initial stage of printing and reproducibility of fine lines after printing resistance, the amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less.

The toner of the present invention may contain a colorant other than CIPigment Red 188 as long as the effects of the present invention are not impaired, but the content of CIPigment Red 188 is preferably 80 in the colorant. It is mass% or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 100% by mass.

In the present invention, the charge control agent contains a metal compound of a benzylic acid compound.

As the metal compound of the benzylic acid compound, the formula (II):

(In the formula, Z is boron or aluminum, s is an integer of 2 or more, and t is an integer of 1 or more)
A compound which is a compound represented by is preferable.

In the present invention, among the metal compounds of the benzylic acid compound represented by the formula (II), a metal complex compound in which Z is boron is preferable.

Commercially available products of the metal compound of benzylic acid represented by the formula (II) include "LR-147" (Z: boron, manufactured by Carlit Japan Co., Ltd.) and "LR-297" (Z: aluminum, manufactured by Carlit Japan Co., Ltd.). And so on.

The content of the metal compound of the benzylic acid compound is preferably 0.3 parts by mass or more, more preferably 0.4 parts by mass or more, and is high temperature with respect to 100 parts by mass of the binder resin from the viewpoint of initial charge rising property. From the viewpoint of maintaining chargeability in a high humidity environment, it is preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, and further preferably 1.0 part by mass or less.

The toner of the present invention may contain a charge control agent other than the metal compound of the benzylic acid compound as long as the effect of the present invention is not impaired, but the content of the metal compound of the benzylic acid compound is charge control. In the agent, it is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 100% by mass.

The toner of the present invention contains additives such as a mold release agent, a magnetic powder, a fluidity improver, a conductivity modifier, a reinforcing filler such as a fibrous substance, an antioxidant, and a cleanability improver. May be good.

As the release agent, hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene polyethylene copolymer wax, microcrystallin wax, paraffin wax, Fishertropch wax, sazole wax and their oxides; carnauba wax, montan Waxes and ester waxes such as deoxidizing waxes and fatty acid ester waxes; fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and the like can be mentioned, and these can be used alone or in combination of two or more.

The melting point of the release agent is preferably 60 ° C. or higher, more preferably 70 ° C. or higher from the viewpoint of toner transferability, and preferably 160 ° C. or lower, more preferably 140 ° C. or higher from the viewpoint of low temperature fixability. Below, it is more preferably 120 ° C. or lower, still more preferably 110 ° C. or lower.

The content of the release agent is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint of low temperature fixability and offset resistance of the toner and dispersibility in the binder resin. It is preferably 1.0 part by mass or more, more preferably 1.5 part by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, still more preferably 7 parts by mass or less.

The toner of the present invention may be a toner obtained by any conventionally known method such as a melt-kneading method, an emulsification phase inversion method, a polymerization method, etc., but from the viewpoint of productivity and dispersibility of the colorant, the toner may be obtained. Crushed toner by the melt-kneading method is preferable. In the case of crushed toner by the melt-kneading method, for example, raw materials such as a binder resin, a colorant, a mold release agent, and a charge control agent are uniformly mixed with a mixer such as a Henshell mixer, and then a closed kneader, 1 shaft or 2 It can be manufactured by melt-kneading, cooling, crushing, and classifying with a shaft extruder, an open roll type kneader, or the like.

It is preferable to use an external additive for the toner of the present invention in order to improve transferability. Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin particles such as melamine-based resin fine particles and polytetrafluoroethylene resin fine particles. The above may be used together. Among these, silica is preferable, and from the viewpoint of toner transferability, hydrophobicized silica is more preferable.

Examples of the hydrophobizing agent for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octylliethoxysilane (OTES), and methyltriethoxysilane. Be done.

The average particle size of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, and further, from the viewpoint of toner chargeability, fluidity, and transferability. It is preferably 90 nm or less.

From the viewpoint of the chargeability, fluidity, and transferability of the toner, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass, based on 100 parts by mass of the toner before being treated with the external additive. More than parts, more preferably 0.3 parts by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less.

The volume median particle diameter (D ₅₀ ) of the toner of the present invention is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. In the present specification, the volume median particle size (D ₅₀ ) means a particle size in which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size. When the toner is treated with an external additive, the volume median particle diameter of the toner particles before the toner is treated with the external additive is defined as the volume median particle diameter of the toner.

The toner of the present invention can be used as it is as a toner for one-component development or as a toner for two-component development used by mixing with a carrier in a one-component development method or a two-component development method image forming apparatus, respectively.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The physical properties of the resin and the like were measured by the following methods.

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

[Resin glass transition temperature]
Using the differential scanning calorimeter "DSC210" (manufactured by Seiko Electronics Co., Ltd.), weigh 0.01 to 0.02 g of the sample in an aluminum pan, raise the temperature to 200 ° C, and then lower the temperature from that temperature at a rate of 10 ° C / min- Cool to 10 ° C. Next, the sample is heated at a heating rate of 10 ° C./min and measured. The temperature is raised from 25 ° C to 120 ° C at a heating rate of 10 ° C / min, and the intersection of the extension of the baseline below the maximum heat absorption peak temperature and the tangent line showing the maximum slope from the peak rise to the peak peak. Let the temperature be the glass transition temperature.

[Acid value of resin]
Measure based on the method of JIS K0070. However, only the measurement solvent is changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Melting point of mold release agent]
Using the differential scanning calorimeter "DSC210" (manufactured by Seiko Electronics Co., Ltd.), weigh 0.01 to 0.02 g of the sample in an aluminum pan, raise the temperature to 200 ° C, and then lower the temperature from that temperature to 0 at a rate of 10 ° C / min. Cool to ° C. Next, the sample is heated to 180 ° C. at a heating rate of 10 ° C./min and measured. The maximum peak temperature of endothermic observed from the melt endothermic curve obtained there is taken as the melting point of the release agent.

[Average particle size of external additive]
The average particle size refers to the number average particle size, and the particle size (average value of major axis and minor axis) of 500 particles is measured from a scanning electron microscope (SEM) photograph and used as the average value of those numbers.

[Medium particle size of toner]
Measuring machine: Coulter Multisizer II (manufactured by Beckman Coulter Co., Ltd.)
Aperture diameter: 100 μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (manufactured by Beckman Coulter Co., Ltd.)
Electrolyte: Isoton II (manufactured by Beckman Coulter Co., Ltd.)
Dispersion solution: Emulgen 109P (manufactured by Kao Co., Ltd., polyoxyethylene lauryl ether, HLB (griffin): 13.6) was dissolved in an electrolytic solution to adjust to 5% by mass. Was added and dispersed with an ultrasonic disperser (machine name: US-1, manufactured by SND Co., Ltd., output: 80 W) for 1 minute, then 25 mL of the electrolytic solution was added, and the mixture was further added to the ultrasonic disperser. Disperse for 1 minute to prepare a sample dispersion.
Measurement conditions: To 100 mL of the electrolytic solution, add the sample dispersion so that the particle size of 30,000 particles can be measured in 20 seconds, measure 30,000 particles, and measure the volume from the particle size distribution. Determine the medium particle size (D ₅₀ ).

Resin Production Example 1 [Resin A]
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 3308g, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 341g, fumaric acid 792g (in the carboxylic acid component) Content: 73 mol%), 5 g of hydroquinone, and 10 g of dibutyltin oxide were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, dehydration tube, stirrer and thermocouple, and placed at 180 ° C. in a nitrogen atmosphere. After the reaction was carried out by raising the temperature to 210 ° C. for 5 hours, the reaction was carried out at 8.3 kPa for 1 hour. Then, 480 g of trimellitic anhydride was added and reacted at normal pressure for 1 hour, and then the reaction was carried out at 8.3 kPa until a desired softening point was reached to obtain a polyester resin. The softening point of the obtained resin was 155.3 ° C, the glass transition temperature was 64.7 ° C, and the acid value was 33.8 mgKOH / g.

Resin Production Example 2 [Resin B]
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 882g, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 2594g, terephthalic acid 1499g, and 2-ethyl 25 g of tin (II) hexaneate was placed in a 5-liter four-necked flask equipped with a dehydration tube, a stirrer and a thermocouple during nitrogen introduction, and reacted at 230 ° C. for 8 hours under a nitrogen atmosphere, and then 8 kPa. The reaction was carried out until a desired softening point was reached, to obtain a polyester resin. The softening point of the obtained resin was 101.2 ° C, the glass transition temperature was 60.4 ° C, and the acid value was 3.4 mgKOH / g.

Examples 1 to 3, Comparative Examples 1 and 2, and Reference Example 1
The binder resin, colorant, charge control agent, and mold release agent shown in Table 1 are premixed for 1 minute using a Henschel mixer, and then a twin-screw extruder "PCM-87" (manufactured by Ikegai Iron Works) is used. And melt-kneaded. The conditions for melt-kneading were a feed amount of the raw material of 3.0 kg / min and a shaft rotation speed of 180 r / min in the screw kneaded part (peripheral speed of shaft rotation of 0.30 m / sec) to obtain a kneaded product. The obtained kneaded product was cooled to 20 ° C. or lower while being rolled with a cooling roll, and the cooled melt-kneaded product was roughly pulverized to 3 mm with Rotoplex (manufactured by Toa Kikai Co., Ltd.).
_{The obtained pyroclastic material is roughly crushed to a volume medium particle size (D 50} ) of 1.5 to 2.5 mm using a cutter mill (manufactured by Nara Kikai Seisakusho Co., Ltd.), and then a collision plate type jet mill "I-20 type" ( Finely pulverized with Nippon Pneumatic Industries Co., Ltd.).
Further, the obtained pulverized product was classified by an air flow classifier "DSF type" (manufactured by Nippon Pneumatic Industries, Ltd.) to obtain toner particles having _{a volume median particle diameter (D 50) of 7.0 μm.}

To 100 parts by mass of the obtained toner particles, 0.5 parts by mass of hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: DMDS, average particle diameter 16 nm) and hydrophobic silica "RY-50" (Made by Nippon Aerosil Co., Ltd., Hydrophobicizing agent: Silicone oil, average particle size 40 nm) 1.5 parts by mass was added and mixed with a Henshell mixer for 5 minutes to obtain toner.

Test Example 1 [Initial fog]
Toner was mounted on the non-magnetic one-component developing device "COREFIDO C530dn" (manufactured by Oki Data Corporation), and blank printing was performed. The printer was stopped in the middle of blank paper printing, and "Scotch (registered trademark) mending tape 810" (manufactured by Sumitomo 3M Ltd., width: 18 mm) was pasted on the photoconductor, and the toner on the photoconductor was peeled off. The tape peeled from the photoconductor and the unused tape are attached to unused blank paper, and the color difference (ΔE) between the tape peeled from the photoconductor and the unused tape is measured with X-Rite eXact (manufactured by X-Rite). It was measured and the value was taken as the initial fog. The results are shown in Table 1.

Test Example 2 [Thin line reproducibility]
Toner was mounted on a non-magnetic one-component developing device "COREFIDO C530dn" (manufactured by Oki Data Corporation), and 10,000 sheets were printed on A4 paper at a printing rate equivalent to 1%. After printing 10000 sheets, one 2dot / 3space / horizontal line pattern was printed, the reproducibility of the 2dot line was visually confirmed, and the fine line reproducibility was evaluated according to the following evaluation criteria. The results are shown in Table 1.
〔Evaluation criteria〕
○: 2dot line looks beautiful △: Slightly rough on the 2dot line ×: Clearly rough on the 2dot line

Test Example 3 [Image density]
Toner was mounted on a non-magnetic one-component developing device "COREFIDO C530dn" (manufactured by Oki Data Corporation), and a solid image of 2 cm x 3 cm (toner adhesion amount: 0.4 mg / cm ² ) was obtained. The obtained image density was measured with X-Rite eXact (manufactured by X-Rite). The results are shown in Table 1.

From the above results, it can be seen that the toners of Examples 1 to 3 can obtain an image in which initial fog is suppressed and fine line reproducibility is good at an appropriate image density.
On the other hand, the toner of Comparative Example 1 in which the content of the polyester resin using the aliphatic dicarboxylic acid compound is low has insufficient fine line reproducibility, and the toner in which the metal compound of the salicylic acid derivative is used as the charge control agent Initial fog has occurred in the toner of No. 2.
In addition, from the comparison between Comparative Example 2 and Reference Example 1, even if CIPigment Red 188 is used, if the amount is small, the image density will be slightly lower, but the initial fog will not be a problem and the fine line reproducibility will be good. Therefore, it can be seen that the problems for these are recognized only when a large amount of CI Pigment Red 188 is used.

The toner for electrophotographic of the present invention is used, for example, for developing a latent image formed by an electrostatic charge image developing method, an electrostatic recording method, an electrostatic printing method, or the like.

Claims (4)

An electrophotographic toner containing a binder resin, a colorant, and a charge control agent, wherein the binder resin contains an alcohol component and a carboxylic acid component containing 60 mol% or more of an aliphatic dicarboxylic acid compound. It contains 50% by mass or more of polyester resin A which is a polycondensate, the colorant contains 5 parts by mass or more of CI Pigment Red 188 with respect to 100 parts by mass of the binder resin, and the charge control agent is benzyl. An electrophotographic toner containing a metal compound of an acid compound. The electrophotographic toner according to claim 1, wherein the aliphatic dicarboxylic acid compound is fumaric acid or maleic acid. The electrophotographic toner according to claim 1 or 2, wherein the content of the metal compound of the benzylic acid compound is 0.3 parts by mass or more with respect to 100 parts by mass of the binder resin. The electrophotographic toner according to any one of claims 1 to 3, further comprising a polyester resin B having a softening point lower than that of the polyester resin A by 15 ° C. or more.