JP2019095575A - Toner for electronic photography - Google Patents

Abstract

To provide electrophotographic toner excellent in suppression of fogging and in thin line reproducibility after long-term printing.SOLUTION: The electrophotographic toner contains a binder resin, colorant, and charge control agent. The binder resin contains a polyester resin A of 50 mass% or more, which is a polycondensate of an alcohol component and a carboxylic acid component containing an aliphatic dicarboxylic acid compound of 60 mol% or more, the colorant contains 5 parts by mass or more of C.I.Pigment Red 188 based on 100 parts by mass of the binder resin, and the charge control agent contains a metal compound of a benzilic acid compound.SELECTED DRAWING: None

Description

  The present invention relates to an electrophotographic toner used for developing a latent image formed in, for example, an electrophotographic method, an electrostatic recording method, an electrostatic printing method and 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 is disclosed which is characterized in that it contains CI Pigment Red 48: 1 and one or more pigments selected from 187, 188 and 269.

  Patent Document 2 describes a toner including a binder resin, a colorant, a release agent, and a charge control agent, wherein the binder resin contains a resin H and a resin L different in softening point, The resin H is a non-linear polyester having a softening point of 140 ° C. to 170 ° C., and the resin L is a linear having a softening point of 85 ° C. to 95 ° C. and a peak top molecular weight of 6,000 to 8,000. It is a polyester, The mass ratio (resin H / resin L) of the resin H and the resin L is 50/50 to 80/20, and the releasing agent is 95 moles of α-olefin having 26 to 28 carbon atoms. % Of the α-olefin polymer obtained by polymerizing a monomer containing at least 25% by weight, 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.

JP 2004-117649 A JP, 2015-114649, A

Although CI Pigment Red 188 is not widely used as a colorant for toners, it has a color close to an amber color than ordinary red pigments, and toners of such color may be desired.
However, when CI Pigment Red 188 is used, fogging is likely to occur due to insufficient charging at the initial stage of printing due to a decrease in toner charge stability, and thin line reproducibility is reduced due to excessive charging 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 thin line reproducibility after printing.

  The present invention is a toner for electrophotography comprising a binder resin, a colorant and a charge control agent, wherein the binder resin comprises 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, contains 50% by mass or more, and the colorant contains 5 parts by mass or more of CI Pigment Red 188 with respect to 100 parts by mass of the binding resin, The present invention relates to an electrophotographic toner, wherein the control agent contains a metal compound of a benzylic acid compound.

  The toner for electrophotography of the present invention exhibits excellent effects in fog suppression at the initial stage of printing and thin line reproducibility after printing.

The toner for electrophotography of the present invention (hereinafter, also simply referred to as toner) is 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. The metal compounds of the benzyl acid compounds are respectively contained, and in the present invention, the combination of these improves fog suppression in the initial stage of printing and thin-line reproducibility after printing, which are the problems of toners including CI Pigment Red 188. 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 rising property is effective, and after printing, an aliphatic dicarboxylic acid compound having no aromatic ring It is surmised that excessive charge can be suppressed and the thin-line reproducibility can be stabilized by causing the region derived from to leak the charge appropriately.

  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-based compound.

  Examples of aliphatic dicarboxylic acid compounds include fumaric acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, anhydrides of these acids, and alkyl esters having 1 to 3 carbon atoms. Among these, from the viewpoint of fine line reproducibility after printing, aliphatic dicarboxylic acid compounds having 3 to 6 carbon atoms are preferable, and fumaric acid or maleic acid is more preferable. In addition, carbon number of the alkyl group of an alkyl ester part is not included in said carbon number.

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

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

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

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

(Wherein, OR and RO are oxyalkylene groups, R is ethylene and / or propylene groups, x and y indicate the average addition mole number of alkylene oxide, and each is a positive number, and x and y are The sum value is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, further preferably 4 or less)
It is preferable to include the alkylene oxide adduct of bisphenol A represented by As the alkylene oxide adduct of bisphenol A represented by the formula (I), a polyoxypropylene adduct of 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) propane Polyoxyethylene adducts and the like can be mentioned. 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 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, 1,4-butene Aliphatic diols such as diol, 1,3-butanediol, neopentyl glycol and the like, alcohols having trivalent or higher such as glycerin and the like can be mentioned.

  The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound.

  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, and still more preferably 0.75 or more, from the viewpoint of adjusting the softening point of the polyester resin. Preferably, it is 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 cocatalyst, a polymerization inhibitor, etc. Can be produced by polycondensation at a temperature of 130 ° C. or more, more preferably 170 ° C. or more, and preferably 250 ° C. or less, more preferably 240 ° C. or less.

  Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bis triethanol aminate, and the like, with preference given to tin compounds. 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 of the alcohol component and the carboxylic acid component. Preferably it is 1 mass part or less. Examples of the esterification promoter include gallic acid and the like. The amount of the esterification promoter is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, based on 100 parts by mass of the total 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-butyl catechol and the like. The amount of the polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, based on 100 parts by mass of the total of the alcohol component and the carboxylic acid component. Preferably it is 0.1 mass part or less.

  In the present invention, the polyester resin may be a polyester resin which has been modified to such an extent that the properties thereof are not substantially impaired. As the modified polyester resin, for example, grafting or blocking with phenol, urethane, epoxy or the like according to the method described in JP-A-11-1336668, JP-A-10-239903, JP-A-8-20636, etc. Among the modified polyester resins, a urethane-modified polyester resin in which the polyester resin is urethane-stretched with a polyisocyanate compound is preferable.

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

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

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

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

  The alcohol component and the carboxylic acid component of the polyester resin B may be, for example, the same as those of the polyester resin A, but the carboxylic acid component preferably contains an aromatic dicarboxylic acid compound, and the content thereof is carboxylic acid Among the components, it is 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 between the softening points of the polyester resin A and the polyester resin B is preferably 15 ° C. or more, more preferably 20 ° C. or more, from the viewpoint of achieving both low temperature fixability and high temperature offset resistance, and melting during toner production The temperature is preferably 60 ° C. or less, more preferably 55 ° C. or less, from the viewpoint of improving the pigment dispersibility in kneading and the dispersibility of the charge control agent.

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

  The glass transition temperature of the polyester resin B is preferably 40 ° C. or more, more preferably 50 ° C. or more from the viewpoint of storage stability, and preferably 80 ° C. or less, more preferably 70 ° C. from the viewpoint of low temperature fixability. It is less than ° 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, more preferably from the viewpoint of charge stability in a high temperature and high humidity environment. Is 20 mg KOH / g or less, more preferably 10 mg KOH / g or less.

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

  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, and still more preferably 100% by mass in the binder resin.

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

  In the present invention, the colorant contains CI Pigment Red 188.

  The content of CI Pigment Red 188 can be appropriately selected according to the color tone etc. of the target toner, but in the present invention, CI Pigment Red 188 alone is large enough to ensure the image density as a red toner. When CI Pigment Red 188 is used, the effects of the present invention are more prominent. Therefore, the content of CI Pigment 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 still more preferably 9 parts by mass or more with respect to 100 parts by mass of the binder resin. And from the viewpoint of suppression of fog in the initial stage of printing and thin line reproducibility after printing, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 12 parts by mass or less.

  The toner of the present invention may contain a colorant other than CI Pigment Red 188, as long as the effects of the present invention are not impaired. However, the content of CI Pigment Red 188 is preferably 80 in the colorant. The content is preferably at least 90% by mass, more preferably at least 95% by mass, and 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 benzyl acid compound, from the viewpoint of the chargeability of the toner, the formula (II):

(Wherein, Z is boron or aluminum, s is an integer of 2 or more, t is an integer of 1 or more)
The compound which is a compound represented by these 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.

  Commercial products of the metal compound of benzyl acid represented by the formula (II) include “LR-147” (Z: boron, manufactured by Nippon Carlit Co., Ltd.), “LR-297” (Z: aluminum, manufactured by Japan Carlit Co., Ltd.) Etc.

  The content of the metal compound of the benzyl acid compound is preferably 0.3 parts by mass or more, more preferably 0.4 parts by mass or more, from the viewpoint of the initial charge rising property with respect to 100 parts by mass of the binder resin. From the viewpoint of maintaining the 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 still more preferably 1.0 parts 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 insofar as the effects of the present invention are 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, and still more preferably 100% by mass.

  The toner of the present invention contains additives such as a mold release agent, magnetic powder, fluidity improver, conductivity adjustor, reinforcing filler such as fibrous substance, antioxidant, cleanability improver, etc. It is also good.

  Examples of mold release agents include hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene polyethylene copolymer wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, Sazol wax, and oxides thereof; carnauba wax, montan Waxes and ester-based waxes such as deacidified 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 releasing agent is preferably 60 ° C. or more, more preferably 70 ° C. or more from the viewpoint of transferability of the toner, and preferably 160 ° C. or less, more preferably 140 ° C. from the viewpoint of low temperature fixability. The temperature is further preferably 120 ° C. or less, more preferably 110 ° C. or less.

  The content of the releasing agent is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the binder resin from the viewpoints of low-temperature fixability and offset resistance of the toner and the dispersibility in the binder resin. The amount is preferably 1.0 part by mass or more, more preferably 1.5 parts 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 of conventionally known methods such as a melt-kneading method, an emulsion phase inversion method, a polymerization method, etc., but from the viewpoint of productivity and dispersibility of colorants, A pulverized toner by a melt-kneading method is preferred. In the case of a pulverized toner by the melt-kneading method, for example, after uniformly mixing raw materials such as a binder resin, a colorant, a release agent, a charge control agent and the like with a mixer such as a Henschel mixer, a closed kneader, uniaxial or 2 It can be produced by melt-kneading with a shaft extruder, an open roll kneader, etc., followed by cooling, crushing and classification.

  In the toner of the present invention, an external additive is preferably used in order to improve the 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 resin fine particles and polytetrafluoroethylene resin fine particles, and the like. The above may be used in combination. Among these, silica is preferable, and from the viewpoint of the transferability of the toner, hydrophobic silica treated with hydrophobic treatment is more preferable.

  Examples of hydrophobizing agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), methyltriethoxysilane, etc. Be

  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, from the viewpoint of chargeability, flowability and transferability of the toner. Preferably it is 90 nm or less.

  The content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass with respect to 100 parts by mass of the toner before being treated with the external additive, from the viewpoints of chargeability, fluidity, and transferability of the toner. The amount is preferably at least 0.3 parts by mass, and more preferably at most 5 parts by mass, more preferably at most 3 parts by mass.

The volume median particle size (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 at which the cumulative volume frequency calculated by volume fraction is 50% as calculated from the smaller particle size. When the toner is treated with an external additive, the volume median particle size of the toner particles before being treated with the external additive is taken as the volume median particle size of the toner.

  The toner of the present invention can be used as an one-component developing toner as it is or as a two-component developing toner to be used by mixing with a carrier, in an image forming apparatus of a one-component developing system or a two-component developing system.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples. Physical properties of the resin and the like were measured by the following methods.

[Softening point of resin]
Using a 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 is applied by a plunger, diameter 1 mm, length 1 mm Push out of the nozzle. The plunger drop amount of the flow tester is plotted against the temperature, and the temperature at which half of the sample flowed out is taken as the softening point.

[Glass transition temperature of resin]
Using a differential scanning calorimeter “DSC 210” (manufactured by Seiko Instruments Inc.), measure 0.01 to 0.02 g of a sample in an aluminum pan, raise the temperature to 200 ° C., and decrease the temperature from the temperature by 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 endothermic peak temperature and the tangent showing the maximum slope from the rising portion to the peak of the peak The temperature is taken as the glass transition temperature.

[Acid value of resin]
It measures based on the method of JISK0070. However, only the measurement solvent is changed to a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)) from a mixed solvent of ethanol and ether defined in JIS K0070.

Melting point of mold release agent
Using a differential scanning calorimeter “DSC 210” (manufactured by Seiko Instruments Inc.), measure 0.01 to 0.02 g of a sample in an aluminum pan, raise the temperature to 200 ° C., and decrease the temperature from 0 to 10 ° C./min. Cool down to ° C. Next, the sample is heated to 180 ° C. at a heating rate of 10 ° C./min and measured. The highest endothermic peak temperature observed from the melting 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 a number average particle size, and the particle size (average value of the major axis and the minor axis) of 500 particles is measured from a scanning electron microscope (SEM) photograph, and the number average value is taken.

[Toner volume median particle size]
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 Corporation, polyoxyethylene lauryl ether, HLB (glyphin): 13.6) dissolved in electrolyte to adjust to 5% by mass Dispersion conditions: 10 mg of measurement sample in 5 mL of the dispersion Is added, and dispersed for 1 minute with an ultrasonic disperser (machine name: US-1, manufactured by SND Co., Ltd., output: 80 W), and then 25 mL of the electrolyte is added, and further, to the ultrasonic disperser Disperse for 1 minute to prepare a sample dispersion.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte so that the particle size of 30,000 particles can be measured in 20 seconds, 30,000 particles are measured, and the volume is determined from the particle size distribution. Determine the median particle size (D ₅₀ ).

Resin Production Example 1 [Resin A]
3308 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 341 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 792 g of fumaric acid (in carboxylic acid component) Content: 73 mol%), 5 g of hydroquinone and 10 g of dibutyltin oxide in a 5-liter four-necked flask equipped with a nitrogen introducing tube, a dehydrating tube, a stirrer and a thermocouple, and under a nitrogen atmosphere at 180 ° C. The reaction was carried out by raising the temperature from 5 ° C. to 210 ° C. over 5 hours, and then the reaction was performed at 8.3 kPa for 1 hour. Thereafter, 480 g of trimellitic anhydride was added and reacted at normal pressure for 1 hour, and then the reaction was performed at 8.3 kPa until the 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 mg KOH / g.

Resin Production Example 2 (Resin B)
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 882 g, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 2594 g, terephthalic acid 1499 g, and 2-ethyl After 25 g of tin (II) hexanoate is introduced into a 5-liter four-necked flask equipped with a dehydrating tube, a stirrer and a thermocouple while introducing nitrogen, it is reacted at 230 ° C. for 8 hours under a nitrogen atmosphere, then 8 kPa The reaction was carried out until the 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 mg KOH / g

Examples 1 to 3, Comparative Examples 1 and 2, and Reference Example 1
The binder resin, the colorant, the charge control agent, and the 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 Corp.) is used. The mixture was melted and kneaded. Melt-kneading conditions were such that the feed amount of the raw material was 3.0 kg / min and the screw rotation speed of the screw-kneading portion was 180 r / min (the circumferential speed of shaft rotation 0.30 m / sec) to obtain a kneaded product. The obtained kneaded product was cooled to 20 ° C. or less while rolling 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 crude product obtained is roughly crushed to a volume median particle size (D ₅₀ ) of 1.5 to 2.5 mm using a cutter mill (manufactured by Nara Machinery Co., Ltd.), and then a collision plate type jet mill “I-20 type” ( The product was finely pulverized with Nippon Pneumatic Mfg. Co., Ltd.).
Furthermore, the pulverized product obtained was classified with an air flow classifier “DSF type” (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain toner particles having a volume median particle size (D ₅₀ ) of 7.0 μm.

  100 parts by mass of the obtained toner particles, 0.5 parts by mass of hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobization treatment agent: DMDS, average particle diameter 16 nm) as an external additive, hydrophobic silica "RY-50" (Japan Aerosil Co., Ltd., hydrophobizing agent: silicone oil, average particle diameter 40 nm) 1.5 parts by mass was added, and mixed for 5 minutes with a Henschel mixer to obtain a toner.

Test Example 1 [Initial fog]
The toner was mounted on a non-magnetic one-component developing device "COREFIDO C530dn" (manufactured by Oki Data Co., Ltd.), and white paper printing was performed. During printing on a white paper, the printer was stopped, “Scotch (registered trademark) Mending tape 810” (manufactured by Sumitomo 3M, width: 18 mm) was affixed on the photosensitive member, and the toner on the photosensitive member was peeled off. The tape peeled off from the photoreceptor and the unused tape are attached to unused blank paper, and the color difference (ΔE) between the tape peeled off from the photoreceptor and the unused tape is X-Rite eXact (manufactured by X-Rite) It measured and made the value the initial fog. The results are shown in Table 1.

Test example 2 [thin line reproducibility]
The toner was mounted on a nonmagnetic one-component developing device "COREFIDO C530dn" (manufactured by Oki Data Co., Ltd.), and 10000 sheets were printed on an A4 sheet at a printing rate equivalent to 1%. After printing of 10000 sheets, one 2 dot / 3 space / horizontal line pattern was printed, the reproducibility of 2 dot lines was visually confirmed, and thin line reproducibility was evaluated according to the following evaluation criteria. The results are shown in Table 1.
〔Evaluation criteria〕
○: The 2 dot line looks beautiful や や: The 2 dot line looks slightly loose ×: The 2 dot line clearly has looseness

Test Example 3 [Image Density]
The toner was mounted on a nonmagnetic one-component developing device "COREFIDO C530dn" (manufactured by Oki Data Co., Ltd.) to obtain a solid image (toner adhesion amount: 0.4 mg / cm ² ) of ² cm × 3 cm. The obtained image density was measured by X-Rite eXact (manufactured by X-Rite). The results are shown in Table 1.

From the above results, it can be seen that, in the toners of Examples 1 to 3, the initial fogging is suppressed and the fine line reproducibility is also obtained with an appropriate image density.
On the other hand, the toner of Comparative Example 1 in which the content of the polyester resin containing an aliphatic dicarboxylic acid-based compound is small has insufficient thin-line reproducibility, and a comparative example using a metal compound of a salicylic acid derivative as a charge control agent. The toner of 2 has an initial fog.
In addition, from the comparison of Comparative Example 2 and Reference Example 1, even if CIPigment Red 188 is used, although the image density is slightly lowered if the amount is small, the initial fog does not become a problem, and the thin line reproducibility is also good. Because of this, it can be seen that the problems for these are recognized only when using CI Pigment Red 188 in large quantities.

  The toner for electrophotography 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)

  A toner for electrophotography comprising a binder resin, a colorant and a charge control agent, wherein the binder resin comprises an alcohol component and a carboxylic acid component containing 60 mol% or more of an aliphatic dicarboxylic acid compound. The polyester resin A, which is a polycondensate, is contained in an amount of 50% by mass or more, the colorant contains 5 parts by mass or more of CIpigment 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 toner for electrophotography according to claim 1 or 2, wherein the content of the metal compound of the benzyl acid compound is 0.3 parts by mass or more with respect to 100 parts by mass of the binder resin.   The toner for electrophotography according to any one of claims 1 to 3, further comprising a polyester resin B whose softening point is lower than that of the polyester resin A by 15 ° C or more.