Toner, toner cartridge, image forming apparatus

Abstract

To provide a toner that is excellent in low temperature fixability, excellent in storage life in a high temperature environment even when re-used, and maintains a sufficient electrification amount, a toner cartridge storing the toner, and an image forming apparatus.SOLUTION: A toner of an embodiment has a toner base particle and an external additive. The toner base particle includes a crystalline polyester resin, and a specific ester wax. The external additive includes silica A having a D50 of 10 to 14 nm and monodispersed silica B having a D50 of 90 to 150 nm. The following conditions are satisfied. A content of silica A: 0.1 to 0.8 pts.mass based on 100 pts.mass of the toner base particles. A content of silica B: 0.3 to 1.2 pts.mass based on 100 pts.mass of the toner base particles. A ratio (content of silica B / content of silica A): 1.0 to 5.0. A residual ratio X of silica A: 70% or more. A residual ratio Y of silica B: 30% or more. A ratio (residual ratio X / residual ratio Y): 1.0 to 3.0.SELECTED DRAWING: None

Description

[Technical field]

[0001] An embodiment of the present invention relates to a toner, a toner cartridge, and an image forming apparatus. [Background technology]

[0002] A toner containing a crystalline polyester resin is known (for example, Patent Document 1). A low-temperature fixing toner containing a crystalline polyester resin has excellent low-temperature fixing properties. However, when an image forming apparatus using low-temperature fixing toner is operated in a high-temperature environment, the following problems occur. - As the temperature inside the image forming device rises, the developer containing the low-temperature fixing toner cakes. As a result, the developer becomes clogged in the conveying section inside the developing device, causing image defects. - Crystalline polyester resin is highly hygroscopic, so the toner charge decreases and toner scattering worsens, resulting in toner contamination inside the machine.

[0003] Therefore, it is very difficult for low-temperature fixing toner to maintain its storage stability and charge amount in a high-temperature environment while maintaining its low-temperature fixing ability. In particular, in image forming devices with a recycling system, toner from which external additives have been removed from the surface may be returned to the developing device and reused. Therefore, caking and a decrease in charge amount are more likely to occur. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3693327 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a toner which has excellent low-temperature fixing properties, excellent storage stability in high-temperature environments even when reused, and which sufficiently maintains its charge amount; and to provide a toner cartridge and an image forming apparatus containing said toner. [Means for solving the problem]

[0006] The toner of the embodiment has toner base particles and an external additive attached to the surface of the toner base particles. The toner base particles contain a crystalline polyester resin, an ester wax, and a colorant. The external additive contains silica A and monodispersed silica B. Silica A has an average primary particle diameter D 50 The average primary particle diameter D of monodispersed silica B is 10 to 14 nm. 50 is 90 to 150 nm. The ester wax is a condensation polymer of a first monomer group and a second monomer group. The first monomer group is composed of at least three or more kinds of carboxylic acids. The second monomer group is composed of at least three or more kinds of alcohols. The ratio of the carboxylic acid having 18 or less carbon atoms in the first monomer group is 5% by mass or less based on 100% by mass of the first monomer group. The ratio of the alcohol having 18 or less carbon atoms in the second monomer group is 20% by mass or less based on 100% by mass of the second monomer group. The maximum carbon number C in the first monomer group n The ratio of the carboxylic acid in the first monomer group is 70 to 95% by mass relative to 100% by mass of the first monomer group. m The proportion of the alcohol is 70 to 90% by mass with respect to 100% by mass of the second monomer group. The content of silica A is 0.1 to 0.8 parts by mass with respect to 100 parts by mass of the toner base particles. The content of silica B is 0.3 to 1.2 parts by mass with respect to 100 parts by mass of the toner base particles. The ratio of the content of silica B to the content of silica A is 1.0 to 5.0. The residual rate X of silica A calculated by the following formula (1) is 70% or more. The residual rate Y of silica B calculated by the following formula (2) is 30% or more. The ratio of the residual rate X to the residual rate Y is 1.0 to 3.0. Survival rate X=(N a2 / N a1 )×100...Equation (1) Survival rate Y=(N b2 / N b1 )×100...Equation (2) In formula (1), N a1 is the number of silica A particles attached to the toner of the embodiment; N a2 is the number of silica A particles attached measured on particles z obtained by the following method Z. In formula (2), N b1 is the number of silica B particles attached to the toner of the embodiment; N b2 is the number of silica particles B attached, measured for particles z obtained by the following method Z. Method Z: An aqueous liquid containing the toner of the embodiment, water, and a surfactant is subjected to ultrasonic treatment under conditions of 20°C, 1000 Hz, and 10 minutes, and then centrifuged under conditions of 20°C, 1000 rpm, and 15 minutes, the separated external additives are removed, and then the particles obtained by drying are designated as particles z. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a schematic structure of an image forming apparatus according to an embodiment; [Diagram 2] FIG. 2 is a perspective view of a developing device of the image forming apparatus of FIG. [Diagram 3] 2 is a side view of a developing device of the image forming apparatus of FIG. 1. [Figure 4] FIG. 13 is a diagram illustrating an example of a schematic structure of an image forming apparatus according to another embodiment. [Diagram 5] 5 is a perspective view of a modified example of the developing device of the image forming apparatus in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The toner according to the embodiment will be described below. The toner of the embodiment includes toner base particles and an external additive. The toner base particles contain a crystalline polyester resin, an ester wax, and a colorant. The external additive contains silica A and monodispersed silica B. The average primary particle diameter D of silica A is 50 The average primary particle diameter D of monodispersed silica B is 10 to 14 nm. 50 is 90 to 150 nm.

[0009] The crystalline polyester resin will now be described. The crystalline polyester resin functions as a binder resin. In the embodiment, a polyester resin having a ratio of softening temperature to melting temperature (softening temperature / melting temperature) of 0.8 to 1.2 is defined as a "crystalline polyester resin". Moreover, a polyester resin whose ratio of the softening temperature to the melting temperature (softening temperature / melting temperature) is less than 0.8 or exceeds 1.2 is defined as a "non-crystalline polyester resin".

[0010] Examples of the crystalline polyester resin include condensation polymers of divalent or higher alcohols and divalent or higher carboxylic acids. Examples of the dihydric or higher alcohol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-butenediol, polyoxypropylene, polyoxyethylene, glycerin, pentaerythritol, trimethylolpropane, etc. As the dihydric or higher alcohol, 1,4-butanediol and 1,6-hexanediol are preferred. Examples of the divalent or higher carboxylic acid include adipic acid, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, azelaic acid, succinic acid substituted with an alkyl group or an alkenyl group, cyclohexanedicarboxylic acid, trimellitic acid, pyromellitic acid; acid anhydrides thereof; and esters thereof. Examples of succinic acid substituted with an alkyl or alkenyl group include succinic acid substituted with an alkyl or alkenyl group having 2 to 20 carbon atoms. Examples include n-dodecenyl succinic acid, n-dodecyl succinic acid, etc. As the divalent or higher carboxylic acid, fumaric acid is preferred. However, the crystalline polyester resin is not limited to the condensation polymer of the divalent or higher alcohol and the divalent or higher carboxylic acid exemplified here. The crystalline polyester resin may be used alone or in combination of two or more kinds.

[0011] The mass average molecular weight of the crystalline polyester resin is 6×10 3 ~18×10 3 is preferred, 8×10 3 ~14×10 3 When the mass average molecular weight of the crystalline polyester resin is equal to or more than the lower limit, the toner has excellent low-temperature fixing property, and when the mass average molecular weight of the crystalline polyester resin is equal to or less than the upper limit, the toner has excellent offset resistance. In this specification, the mass average molecular weight is a value calculated as polystyrene by gel permeation chromatography.

[0012] The melting point of the crystalline polyester resin is preferably 60 to 120° C., more preferably 70 to 115° C., and even more preferably 80 to 110° C. When the melting point of the crystalline polyester resin is equal to or higher than the lower limit, the toner has better heat resistance. When the melting point of the crystalline polyester resin is equal to or lower than the upper limit, the toner has better low-temperature fixing property. The melting point of the crystalline polyester resin can be measured, for example, by a differential scanning calorimeter (DSC).

[0013] The toner base particles may further contain a binder resin other than the crystalline polyester resin, as long as the effects disclosed in the embodiment can be obtained. Examples of other binder resins include non-crystalline polyester resins, styrene-based resins, ethylene-based resins, acrylic-based resins, phenol-based resins, epoxy-based resins, allyl phthalate-based resins, polyamide-based resins, maleic acid-based resins, etc. Among these, non-crystalline polyester resins are preferred. However, the other binder resins are not limited to these examples. In addition, the other binder resins may be used alone or in combination of two or more.

[0014] Examples of the non-crystalline polyester resin include condensation polymers of divalent or higher carboxylic acids and divalent alcohols. Examples of divalent or higher carboxylic acids include divalent or higher carboxylic acids, acid anhydrides of divalent or higher carboxylic acids, esters of divalent or higher carboxylic acids, etc. Examples of esters of divalent or higher carboxylic acids include lower alkyl (carbon number 1 to 12) esters of divalent or higher carboxylic acids. Examples of dihydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, hydrogenated bisphenol A, and alkylene oxide adducts of bisphenol A. However, the dihydric alcohol is not limited to these examples. Examples of the alkylene oxide adduct of bisphenol A include compounds in which an average of 1 to 10 moles of alkylene oxide having 2 to 3 carbon atoms is added to bisphenol A. Examples of the alkylene oxide adduct of bisphenol A include polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (3.3)-2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene (2.0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (2.0)-polyoxyethylene (2.0)-2,2-bis(4-hydroxyphenyl)propane, and polyoxypropylene (6)-2,2-bis(4-hydroxyphenyl)propane. The dihydric alcohol is preferably an alkylene oxide adduct of bisphenol A. The dihydric alcohol may be used alone or in combination of two or more kinds.

[0015] The mass average molecular weight of the amorphous polyester resin is 6×10 3 ~18×10 3 is preferred, 8×10 3 ~14×10 3 When the mass average molecular weight of the non-crystalline polyester resin is equal to or more than the lower limit, the toner has excellent low-temperature fixing property, and when the mass average molecular weight of the non-crystalline polyester resin is equal to or less than the upper limit, the toner has excellent offset resistance.

[0016] The melting temperature of the non-crystalline polyester resin is preferably 60 to 120°C, more preferably 70 to 115°C. When the melting temperature of the non-crystalline polyester resin is equal to or higher than the lower limit of the above-mentioned range, the toner is less likely to adhere to the roller during fixing. As a result, the toner has excellent offset resistance at high temperatures. In addition, the toner has even better heat resistance. When the melting temperature of the non-crystalline polyester resin is equal to or lower than the upper limit of the above-mentioned range, the toner has even better low-temperature fixing property. The melting temperature of the non-crystalline polyester resin can be measured, for example, by a constant test force extrusion type capillary rheometer (flow tester).

[0017] The other binder resins can be obtained, for example, by polymerizing a single or multiple kinds of vinyl polymerizable monomers. Examples of the vinyl polymerizable monomer include aromatic vinyl monomers, ester monomers, carboxylic acid-containing monomers, and amine monomers. Examples of aromatic vinyl monomers include styrene, methylstyrene, methoxystyrene, phenylstyrene, chlorostyrene, and derivatives thereof. Examples of the ester monomer include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and derivatives thereof. Examples of the carboxylic acid-containing monomer include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and derivatives thereof. Examples of the amine monomer include aminoacrylate, acrylamide, methacrylamide, vinylpyridine, vinylpyrrolidone, and derivatives thereof.

[0018] Other binder resins may be obtained by polycondensation of a polymerizable monomer component consisting of an alcohol component and a carboxylic acid component. In polymerizing the polymerizable monomer component, various assistants such as a chain transfer agent, a crosslinking agent, a polymerization initiator, a surfactant, a flocculating agent, a pH adjuster, and a defoaming agent may be used.

[0019] The ester wax will be described. The ester wax is made of two or more ester compounds with different carbon numbers. Because the toner base particles contain the ester wax, the toner has excellent heat resistance.

[0020] The ester wax is a condensation polymer of a first monomer group and a second monomer group. The first monomer group will be described. The first monomer group is composed of at least three or more kinds of carboxylic acids. Therefore, the toner is less likely to aggregate and has excellent heat resistance. The number of kinds of carboxylic acids in the first monomer group is preferably seven or less, and more preferably five or less, in view of the ease of obtaining ester wax.

[0021] Maximum carbon content C n The proportion of the carboxylic acid is 70 to 95% by mass, preferably 80 to 95% by mass, and more preferably 85 to 95% by mass, based on 100% by mass of the first monomer group. n Since the ratio of the carboxylic acid is equal to or greater than the lower limit, the maximum peak of the carbon number distribution of the ester wax is located sufficiently on the high carbon number side, resulting in excellent fluidity of the toner (transportability of the developer). Carbon number C n Since the ratio of the carboxylic acid is equal to or less than the upper limit, the toner has excellent offset resistance at low temperatures. In addition, the ester wax is easily available.

[0022] The ratio of the carboxylic acid having 18 or less carbon atoms in the first monomer group is 5% by mass or less, preferably 0 to 5% by mass, and more preferably 0 to 1% by mass, based on 100% by mass of the first monomer group. When the ratio of the carboxylic acid having 18 or less carbon atoms is equal to or more than the lower limit, the ester wax is easily available. Since the ratio of carboxylic acids having 18 or less carbon atoms is equal to or less than the upper limit, the offset resistance at low temperatures is excellent.

[0023] The content of carboxylic acids with each carbon number in the first monomer group can be measured, for example, by performing mass analysis by FD-MS (Field Desorption Mass Spectrometry) on the product after methanolysis reaction of ester wax. The sum of the ionic intensities of carboxylic acids with each carbon number in the product obtained by measurement with FD-MS is set to 100. The relative value of the ionic intensity of carboxylic acids with each carbon number to the total is calculated. This relative value is the content of carboxylic acids with each carbon number in the first monomer group. In addition, the number of carbon atoms in the carboxylic acid with the largest relative value is set to C n Let us assume that.

[0024] As the carboxylic acid in the first monomer group, a long-chain carboxylic acid is preferable from the viewpoint of easy availability of the ester wax, and a long-chain alkyl carboxylic acid is preferable. The long-chain carboxylic acid is appropriately selected so that the ester wax satisfies a predetermined requirement. The long-chain carboxylic acid is preferably a long-chain carboxylic acid having 19 to 28 carbon atoms, and more preferably a long-chain carboxylic acid having 20 to 24 carbon atoms. When the carbon number of the long-chain carboxylic acid is equal to or more than the lower limit, the toner has better heat resistance. When the carbon number of the long-chain carboxylic acid is equal to or less than the upper limit, the toner has better low-temperature fixability. Examples of long-chain alkyl carboxylic acids include palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, and montanic acid.

[0025] The second monomer group will now be described. The second monomer group is composed of at least three types of alcohols. Therefore, the toner is less likely to aggregate and has excellent heat resistance. The number of types of alcohols in the second monomer group is preferably five or less because ester wax is easily available.

[0026] Maximum carbon content C m The proportion of the alcohol is 70 to 90% by mass, preferably 80 to 90% by mass, and more preferably 85 to 90% by mass, based on 100% by mass of the second monomer group. m Since the proportion of the alcohol is equal to or greater than the lower limit, the maximum peak of the carbon number distribution of the ester wax is located sufficiently on the high carbon number side, resulting in excellent toner fluidity (transportability of the developer). Carbon number C m Since the alcohol content is equal to or less than the upper limit, the toner has excellent offset resistance at low temperatures. In addition, the ester wax is easily available.

[0027] The proportion of the alcohol having 18 or less carbon atoms in the second monomer group is 20% by mass or less, preferably 10 to 20% by mass, and more preferably 15 to 20% by mass, relative to 100% by mass of the second monomer group. When the proportion of the alcohol having 18 or less carbon atoms is equal to or more than the lower limit, the ester wax becomes easy to obtain. Since the proportion of alcohols having 18 or less carbon atoms is equal to or less than the upper limit, the toner has excellent offset resistance at low temperatures.

[0028] The content of alcohols with each carbon number in the second monomer group can be measured, for example, by performing mass analysis by FD-MS on the product after methanolysis reaction of ester wax. The sum of the ion intensities of alcohols with each carbon number in the product obtained by measurement with FD-MS is set to 100. The relative value of the ion intensity of the alcohol with each carbon number to the total is calculated. This relative value is the content of alcohols with each carbon number in the second monomer group. In addition, the carbon number in the alcohol with the carbon number with the largest relative value is set to C m Let us assume that.

[0029] As the alcohol in the second monomer group, a long-chain alcohol is preferred because the ester wax is easily available, and a long-chain alkyl alcohol is more preferred. The long-chain alcohol is appropriately selected so that the ester wax meets certain requirements. As the long-chain alcohol, a long-chain alcohol having 19 to 28 carbon atoms is preferred, and a long-chain alcohol having 20 to 22 carbon atoms is more preferred. When the carbon number of the long-chain alcohol is equal to or greater than the lower limit, the heat resistance of the ester wax is improved, and the toner has even better heat resistance. When the carbon number of the long-chain alcohol is equal to or less than the upper limit, the toner has even better low-temperature fixability. Examples of long-chain alkyl alcohols include palmityl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, ceryl alcohol, and montanyl alcohol.

[0030] The content of the ester compound of each carbon number in the ester wax can be measured, for example, by mass spectrometry using FD-MS. The sum of the ion intensities of the ester compounds of each carbon number in the ester wax obtained by measurement using FD-MS is taken as 100. The relative value of the ion intensity of the ester compound of each carbon number to the total is calculated. This relative value is taken as the content of the ester compound of each carbon number in the ester wax. In addition, the number of carbon atoms in the ester compound of the carbon number with the maximum relative value is taken as C l Let us assume that.

[0031] A method for preparing the ester wax will now be described. The ester wax can be prepared, for example, by esterifying a long-chain carboxylic acid with a long-chain alcohol. In the esterification reaction, it is preferable to use at least three or more long-chain alkyl carboxylic acids and at least three or more long-chain alkyl alcohols, since it is easy to obtain an ester wax that meets certain requirements. By adjusting the amount of each of the at least three long-chain alkyl carboxylic acids and the at least three long-chain alkyl alcohols used, the carbon number distribution of the ester compound contained in the ester wax can be adjusted. The esterification reaction is preferably carried out while heating under a nitrogen stream. The esterification reaction product may be dissolved in a solvent containing ethanol, toluene, etc., and further purified by adding a basic aqueous solution such as an aqueous sodium hydroxide solution to separate the product into an organic layer and an aqueous layer. The aqueous layer can be removed to obtain an ester wax. It is preferable to repeat the purification operation several times.

[0032] The colorant will now be described. The colorant is not particularly limited, and examples thereof include carbon black, cyan, yellow, and magenta pigments, dyes, and the like.

[0033] Examples of carbon black include aniline black, lamp black, acetylene black, furnace black, thermal black, channel black, and ketjen black. Examples of pigments and dyes include Fast Yellow G, Benzidine Yellow, Chrome Yellow, Quinoline Yellow, India Fast Orange, Irgazin Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Lithol Red 2G, Lake Red C, Rhodamine FB, Rhodamine B Lake, DuPont Oil Red, Phthalocyanine Blue, Pigment Blue, Aniline Blue, Chalcone Blue, Ultramarine Blue, Brilliant Green B, Phthalocyanine Green, Malachite Green Oxalate, Methylene Blue Chloride, Rose Bengal, and Quinacridone.

[0034] Colorants are indicated by color index numbers, for example, CI Pigment Black 1, 6, 7, CI Pigment Yellow 1, 12, 14, 17, 34, 74, 83, 97, 155, 180, 185, CI Pigment Orange 48, 49, CI Pigment Red 5, 12, 31, 48, 48:1, 48:2, 48:3, 48:4, 48:5, 49, 53, 53:1, 53:2, 53:3 , 57, 57:1, 81, 81:4, 122, 146, 150, 177, 185, 202, 206, 207, 209, 238, 269, CI Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:5, 15:6, 75, 76, 79, CI Pigment Green 1, 7, 8, 36, 42, 58, CI Pigment Violet 1, 19, 42, CI Acid Red 52, etc. However, the colorant is not limited to these examples. The colorants may be used alone or in combination of two or more.

[0035] The toner base particles may further contain other components in addition to the binder resin, ester wax, and colorant, as long as the effects disclosed in the embodiment are obtained. Examples of other components include additives such as charge control agents, surfactants, basic compounds, flocculants, pH adjusters, and antioxidants. However, the additives are not limited to these examples. In addition, the additives may be used alone or in combination of two or more.

[0036] The charge control agent will now be described. When the toner base particles contain a charge control agent, the toner is easily transferred onto a recording medium such as paper. Examples of the charge control agent include a metal-containing azo compound, a metal-containing salicylic acid derivative compound, a hydrophobic metal oxide, and a polysaccharide clathrate compound. As the metal-containing azo compound, a complex or complex salt in which the metal is iron, cobalt, or chromium, or a mixture thereof is preferable. As the metal-containing salicylic acid derivative compound and the metal oxide hydrophobic metal, a complex or complex salt in which the metal is zirconium, zinc, chromium, or boron, or a mixture thereof is preferable. As the polysaccharide clathrate compound, a polysaccharide clathrate compound containing aluminum (Al) and magnesium (Mg) is preferable.

[0037] The composition of the toner base particles will be described. The content of the crystalline polyester resin is preferably 5 to 25% by mass, more preferably 5 to 20% by mass, and even more preferably 5 to 15% by mass, based on 100% by mass of the toner base particles. When the content of the crystalline polyester resin is equal to or more than the lower limit, the toner has better low-temperature fixing properties. When the content of the crystalline polyester resin is equal to or less than the upper limit, the toner has better offset resistance.

[0038] The content of the ester wax is preferably 3 to 15% by mass, more preferably 3 to 13% by mass, and even more preferably 5 to 10% by mass, based on 100% by mass of the toner base particles. When the content of the ester wax is equal to or more than the lower limit, the toner has better heat resistance. When the content of the ester wax is equal to or less than the upper limit, the toner has better low-temperature fixing property. In addition, the charge amount is easily maintained.

[0039] When the toner base particles contain a non-crystalline polyester resin, the content of the non-crystalline polyester resin is preferably 60 to 90% by mass, more preferably 65 to 85% by mass, and even more preferably 70 to 80% by mass, based on 100% by mass of the toner base particles. When the content of the non-crystalline polyester resin is equal to or more than the lower limit, the toner has excellent offset resistance. When the content of the non-crystalline polyester resin is equal to or less than the upper limit, the toner has even more excellent low-temperature fixing property.

[0040] The content of the colorant is preferably 2 to 13% by mass, more preferably 3 to 8% by mass, based on 100% by mass of the toner base particles. When the content of the colorant is equal to or more than the lower limit, the toner has excellent color reproducibility. When the content of the colorant is equal to or less than the upper limit, the dispersibility of the colorant is excellent. In addition, the charge amount of the toner is easily controlled.

[0041] The external additives will be described. Silica A is usually a secondary particle of silica in which two or more silica particles are coalesced or aggregated. The secondary particle of silica is irregular in shape. The specific shape of the secondary particle is not particularly limited. The shape of the secondary particle may be a polygonal column, a polyhedron, or an ellipsoid. On the other hand, Silica B is composed of single silica particles. In other words, Silica B is a primary particle of silica. Silica B adheres to the surface of the toner base particle in a monodispersed state. A primary particle of silica means a single particle made of silica. The primary particle of silica is preferably spherical, and more preferably a true sphere. Average primary particle size D of silica A 50 is a value measured for composite particles in which two or more silica particles are coalesced or aggregated. Also, the average primary particle diameter D of silica B is 50 is a value measured for a single silica particle.

[0042] The toner of the embodiment has good fluidity and chargeability because the external additive contains silica A. The fluidity and chargeability of the recycled toner are also improved. Average primary particle size D of silica A 50The average primary particle diameter D of silica A is 10 to 14 nm, preferably 11 to 13 nm, and more preferably 11 to 12 nm. 50 Since the amount of silica A adheres to the surface of the toner base particles is equal to or greater than the lower limit, silica A adheres to the surface of the toner base particles appropriately and sufficiently. As a result, silica A exerts a charge imparting effect, improving the chargeability of the toner. This reduces the contamination of the inside of the machine caused by the scattering of recycled toner. Average primary particle size D of silica A 50 Since the amount of silica A is equal to or less than the upper limit, the silica A is less likely to be embedded in the surface of the toner base particles, and the toner has excellent fluidity. Therefore, the contamination of the inside of the machine due to scattering of recycled toner is reduced.

[0043] The content of silica A is 0.1 to 0.8 parts by mass, preferably 0.3 to 0.6 parts by mass, and more preferably 0.4 to 0.5 parts by mass, based on 100 parts by mass of the toner base particles. Since the content of silica A is equal to or more than the lower limit, the fluidity of the toner is improved. Therefore, the developer has excellent transportability. In addition, since the chargeability of the toner is improved, the contamination of the inside of the machine caused by the scattering of recycled toner is reduced. Since the content of silica A is equal to or less than the upper limit, the toner charge amount does not become excessively high, and therefore sufficient image density is ensured in image formation using recycled toner.

[0044] The external additive contains silica B, which provides a spacing effect between toner particles. Therefore, the toner of the embodiment is less likely to aggregate and has good flowability. In addition, soft caking of the toner is less likely to occur. Average primary particle size D of silica B 50 The average primary particle diameter D of silica B is 90 to 150 nm, preferably 100 to 140 nm, and more preferably 115 to 130 nm. 50 Since the ratio is equal to or greater than the lower limit, the spacing effect is exhibited, and as a result, the toner is less likely to aggregate, and the heat resistance and fluidity are improved. Average primary particle size D of silica B 50Since the content of the silica A in the toner particles is equal to or less than the upper limit, the improvement in the chargeability of the toner particles is not easily hindered. As a result, the contamination of the inside of the machine caused by the scattering of recycled toner particles is reduced.

[0045] The content of silica B is 0.3 to 1.2 parts by mass, preferably 0.5 to 1.0 part by mass, and more preferably 0.7 to 0.9 parts by mass, based on 100 parts by mass of the toner base particles. Since the content of silica B is equal to or more than the lower limit, a spacing effect is exhibited, and as a result, the toner is less likely to aggregate, and the heat resistance and flowability are improved. Since the content of silica B is equal to or less than the upper limit, the improvement in the chargeability due to silica A is not easily hindered. As a result, contamination inside the machine due to scattering of recycled toner is reduced.

[0046] The recycled toner at the time of reuse includes toner from which external additives have been removed from the surface, such as transfer residual toner and fog toner. In addition, low-temperature fixing toner is softened at low temperatures and is therefore prone to aggregation. Therefore, compared with normal toner, the fluidity, chargeability, and heat resistance are likely to decrease. As a result, when forming an image using low-temperature fixing toner recycled toner, contamination inside the machine due to toner scattering and a decrease in image density are likely to occur. To solve this problem, the toner of the embodiment has an average primary particle diameter D 50 Therefore, the flowability and chargeability of the recycled toner are improved. In addition, the toner of the embodiment has an average primary particle diameter D 50 It contains silica B, which has a relatively large size. Therefore, the surface of the toner base particles contains silica with a relatively large size. As a result, blocking caused by the coalescence of toner particles due to heat or stress can be prevented. Therefore, the fluidity of the recycled toner and the transportability of the developer in a high-temperature environment are improved. In this manner, in the toner of the embodiment, since the external additive contains two types of silica A and silica B, the toner properties are improved when it is reused.

[0047] The ratio of the content of silica B to the content of silica A (content of silica B / content of silica A) is 1.0 to 5.0, preferably 1.5 to 4.0, and more preferably 2.0 to 3.0. Since the ratio is equal to or greater than the lower limit, the toner charge amount does not become excessively high. Therefore, sufficient image density is ensured in image formation using recycled toner. When the ratio is equal to or less than the upper limit, the chargeability of the toner is improved, and as a result, contamination of the inside of the machine due to scattering of recycled toner is reduced.

[0048] The total content of silica A and silica B is preferably 0.5 to 1.7 parts by mass, more preferably 0.8 to 1.4 parts by mass, per 100 parts by mass of the toner base particles. When the total content of silica A and silica B is equal to or more than the lower limit, the toner has better storage stability. When the total content of silica A and silica B is equal to or less than the upper limit, the toner is easily melted sufficiently during fixing.

[0049] In the toner of the embodiment, the residual rate X of silica A is 70% or more, preferably 75 to 100%, and more preferably 85 to 95%. Since the residual rate X is equal to or more than the lower limit, the chargeability of the toner is improved. As a result, contamination of the inside of the machine due to scattering of recycled toner is reduced. When the residual rate X is equal to or less than the upper limit, the toner is easy to manufacture.

[0050] In the toner of the embodiment, the residual ratio Y of silica B is 30% or more, preferably 40 to 90%, and more preferably 50 to 80%. Since the residual ratio Y is equal to or more than the lower limit, a spacing effect is exhibited. As a result, the toner is less likely to aggregate and has good fluidity. When the residual ratio Y is equal to or less than the upper limit, the toner is easy to manufacture.

[0051] The ratio of the residual rate X to the residual rate Y (residual rate X / residual rate Y) is 1.0 to 3.0, preferably 1.3 to 2.7, and more preferably 1.6 to 2.4. The ratio is equal to or greater than the lower limit, so that the chargeability of the toner is improved. As a result, contamination of the inside of the machine due to scattering of recycled toner is reduced. Since the ratio is equal to or less than the upper limit, the toner charge amount does not become excessively high, and therefore sufficient image density is ensured in image formation using recycled toner.

[0052] The residual rate X is calculated by the following formula (1). Survival rate X=(N a2 / N a1 )×100...Equation (1) In formula (1), N a1 is the number of silica A particles attached to the toner of the embodiment; N a2 is the number of silica A particles attached measured on particles z obtained by the following method Z. Method Z: An aqueous liquid containing the toner of the embodiment, water, and a surfactant is subjected to ultrasonic treatment under conditions of 20°C, 1000 Hz, and 10 minutes, and then centrifuged under conditions of 20°C, 1000 rpm, and 15 minutes, the separated external additives are removed, and then the particles obtained by drying are designated as particles z.

[0053] The residual rate Y is calculated using the following formula (2). Survival rate Y=(N b2 / N b1 )×100...Equation (2) In formula (2), N b1 is the number of silica B particles attached to the toner of the embodiment; N b2 is the number of silica particles B attached, measured for particles z obtained by the following method Z. Method Z: An aqueous liquid containing the toner of the embodiment, water, and a surfactant is subjected to ultrasonic treatment under conditions of 20°C, 1000 Hz, and 10 minutes, and then centrifuged under conditions of 20°C, 1000 rpm, and 15 minutes, the separated external additives are removed, and then the particles obtained by drying are designated as particles z.

[0054] In the above formulas (1) and (2), N a1 , N a2 , N b1 , N b2 is determined by counting the number of silica particles adhering to the surface in a scanning electron microscope (SEM) image. In addition, in the method Z, it is preferable to stir the aqueous liquid containing the toner, water, and surfactant until the toner layer disappears before subjecting the aqueous liquid to ultrasonic treatment. The stirring method is not particularly limited. For example, a stirrer can be used. In the method Z, when removing the desorbed external additive, it is preferable to remove the supernatant liquid from the centrifuge tube by decantation. It is also preferable to add more ion-exchanged water and repeat the centrifugation and decantation again. The number of repetitions is not particularly limited, but it is preferable to repeat it twice. The particles z obtained by the method Z can also be said to be a toner in which at least a part of the external additive is released from the toner of the embodiment.

[0055] Silica A and silica B are not particularly limited. In general, silica particles can be roughly classified into wet silica and calcined silica depending on the manufacturing method. Wet silica can be manufactured, for example, by using sodium silicate made from silica sand as a raw material, neutralizing an aqueous solution containing sodium silicate to precipitate silica, and filtering and drying it (liquid phase method). Calcined silica (dry silica) can be obtained, for example, by reacting silicon tetrachloride in a high-temperature flame. Both wet silica and calcined silica are hydrophobic.

[0056] Silica A and silica B may be subjected to a hydrophobic treatment of the silanol groups on the particle surfaces with, for example, silane, silicone, etc. The hydrophobicity of the hydrophobic silica can be measured, for example, by the following method. Put 50 ml of ion-exchanged water and 0.2 g of sample into a beaker, and add methanol dropwise from a burette while stirring with a magnetic stirrer. Next, as the methanol concentration in the beaker increases, the powder gradually settles, and the volume percentage of methanol in the mixed solution of methanol and ion-exchanged water at the end point when the entire powder has settled is taken as the degree of hydrophobicity (%).

[0057] When the external additive is removed from the toner of the embodiment and the particle diameter of the external additive is measured to obtain a particle diameter distribution, it is believed that at least two maximum silica peaks derived from silica A and silica B are present. In the particle size distribution, it is preferable that at least one of the two maximum peaks is present within the range of 10 to 14 nm and at least one of the maximum peaks is present within the range of 90 to 150 nm. In this case, the average primary particle diameter D 50 can be a mode value (the most frequent value) in the range of 10 to 14 nm in the particle size distribution. 50 can be the mode value (the most frequent value) in the range of 90 to 150 nm in the particle size distribution. The particle size of each silica particle can be measured, for example, by a laser diffraction particle size distribution measuring device.

[0058] However, the external additive may further contain silica other than silica A and silica B, so long as the effects disclosed in the embodiment are obtained. In other words, the external additive may contain silica having an average primary particle diameter D 50 may contain silica having a size of more than 14 nm and less than 90 nm.

[0059] The external additive may further contain inorganic oxides other than silica particles, such as strontium titanate, titanium oxide, alumina, and tin oxide. The silica particles and the particles made of an inorganic oxide may be surface-treated with a hydrophobizing agent in order to improve stability. The inorganic oxide may be used alone or in combination of two or more kinds.

[0060] Average primary particle diameter D of the toner according to the embodiment 50 The volume average primary particle diameter D of the toner is preferably 5.8 to 10.0 μm, and more preferably 7.0 to 9.0 μm. 50 When the volume average primary particle diameter D of the toner is equal to or larger than the lower limit, the toner has excellent fluidity. 50 When it is equal to or less than the upper limit, a sufficient image density is easily ensured.

[0061] The toner production method will be described. The toner of the embodiment can be produced by mixing the toner base particles with the external additives. By mixing the toner base particles with the external additives, the external additives are attached to the surfaces of the toner base particles. The toner base particles of the embodiment can be produced by, for example, a kneading and pulverizing method or a chemical method.

[0062] The kneading and pulverizing method will be described. The kneading and pulverizing method may, for example, be a production method including the following mixing step, kneading step, and pulverizing step. The kneading and pulverizing method may further include the following classification step, if necessary. Mixing step: A step of mixing at least a crystalline polyester resin, an ester wax, and a colorant to obtain a mixture. Kneading step: a step of melt-kneading the mixture to obtain a kneaded product. Crushing step: a step of pulverizing the kneaded material to obtain a pulverized material. Classification step: a step of classifying the pulverized material.

[0063] In the mixing step, the raw materials of the toner are mixed to obtain a mixture. In the mixing step, a mixer may be used. The mixer is not particularly limited. In the mixing step, other binder resins and additives may be used as necessary. In the kneading step, the mixture obtained in the mixing step is melt-kneaded to obtain a kneaded product. A kneader may be used in the kneading step. The kneader is not particularly limited. In the pulverization step, the kneaded product obtained in the kneading step is pulverized to obtain a pulverized product. A pulverizer may be used in the pulverization step. As the pulverizer, various pulverizers such as a hammer mill may be used. In addition, the pulverized product obtained by the pulverizer may be further pulverized. As the pulverizer for further pulverizing the pulverized product, various pulverizers may be used. The pulverized product obtained in the pulverization step may be used as it is as toner base particles, or may be used as toner base particles after a classification step as necessary. In the classification step, the pulverized product obtained in the pulverization step is classified. A classifier may be used in the classification step. The classifier is not particularly limited.

[0064] The chemical method will now be described. In the chemical method, a mixture is obtained by mixing a crystalline polyester resin, an ester wax, a colorant, and, if necessary, other binder resins and additives. The mixture is then melted and kneaded to obtain a kneaded product. The kneaded product is then pulverized to obtain coarsely granulated medium-sized particles. The medium-sized particles are then mixed with an aqueous medium to prepare a mixture. The mixture is then subjected to mechanical shearing to obtain a fine particle dispersion. Finally, the fine particles are aggregated in the fine particle dispersion to form toner base particles.

[0065] A method for adding external additives will be described (external addition step). The external additive is stirred with the toner base particles, for example, by a mixer. The mixer is preferably equipped with a temperature control function. The temperature at which the external additive is attached to the toner base particles is not particularly limited, but is preferably, for example, 15 to 30°C. The higher the temperature at which the external additive is attached to the toner base particles, the more easily silica A and silica B are attached to the toner base particles. Therefore, the residual ratios X and Y tend to be high. There is no particular limitation on the order of deposition of silica A and silica B. In other words, silica A may be deposited first and then silica B, silica B may be deposited first and then silica A, or silica A and silica B may be simultaneously deposited while being stirred.

[0066] The stirring speed when silica A and silica B are attached to the toner base particles is not particularly limited. The stirring speed is appropriately set according to the scale of the manufacturing equipment. For example, 2000 to 3000 rpm is preferable for a laboratory-scale stirrer. The higher the stirring speed when the external additive is attached to the toner base particles, the easier it is for silica A and silica B to adhere to the toner base particles. Therefore, the residual rate X and residual rate Y tend to be higher. The stirring time for silica A and silica B is preferably 180 to 480 seconds. When the stirring time for silica A and silica B is within the above range, silica A and silica B tend to adhere to the toner base particles. Therefore, the residual ratios X and Y tend to be high.

[0067] The external additive before stirring may be sieved using a sieving device as necessary. The sieving device is not particularly limited. Various sieving devices can be used.

[0068] A toner cartridge according to an embodiment will be described. The toner cartridge of the embodiment contains the toner of the above-mentioned embodiment. For example, the toner cartridge has a container, and the toner of the embodiment is contained in the container. The container is not particularly limited, and various containers applicable to the image forming apparatus can be used. The toner of the embodiment may be used as a one-component developer, or may be used in combination with a carrier as a two-component developer.

[0069] Hereinafter, an image forming apparatus according to an embodiment will be described with reference to the drawings. Fig. 1 is a diagram showing an example of a schematic structure of an image forming apparatus capable of reusing collected toner. The copier body 101 shown in FIG. 1 comprises an image forming unit 101A provided on one side of the center; a document placement tray 135 provided on the upper surface; a scanner 136 provided below the document placement tray 135; and multiple-stage paper feed cassettes 142, 143 provided on the lower side.

[0070] Image forming unit 101A has a photosensitive drum 102 that is rotatable in the direction of the arrow; a charging charger 103 that charges the surface of photosensitive drum 102; a laser unit 104 that forms an electrostatic latent image on the surface of photosensitive drum 102; a developing device 105 that develops the electrostatic latent image on photosensitive drum 102 with toner; a transfer charger 106 that transfers the toner image on photosensitive drum 102 to paper; a cleaning device 107 that removes residual toner from photosensitive drum 102; and a supply container 108 provided above developing device 105. An electric charger 103, a laser unit 104, a developing device 105, a transfer charger 106, and a cleaning device 107 are provided around the periphery of the photosensitive drum 102 in this order along the direction of rotation of the photosensitive drum 102. The supply container 108 supplies the toner of the embodiment to the developing device 105. The supply container 108 stores the toner of the embodiment.

[0071] Scanner 136 exposes an original on original placement table 135. Scanner 136 has a light source 137 that irradiates light onto the original, a first reflecting mirror 138 that reflects the light reflected from the original in a predetermined direction, a second reflecting mirror 139 and a third reflecting mirror 140 that sequentially reflect the light reflected from first reflecting mirror 138, and a light receiving element 141 that receives the light reflected from third reflecting mirror 140. Paper feed cassettes 142 and 143 feed paper to image forming unit 101A. The paper is transported upward via transport system 144. Transport system 144 has a transport roller pair 145, a registration roller pair 146, a transfer charger 106, a fixing roller pair 147, and a discharge roller pair 148.

[0072] In the image forming apparatus shown in FIG. 1, image formation is carried out, for example, as follows. First, light is irradiated from light source 137 onto an original placed on original placement table 135. The irradiated light is reflected from the original and transmitted in order through first reflecting mirror 138, second reflecting mirror 139, and third reflecting mirror 140 to be received by light receiving element 141, whereby the original image is read. Next, based on the read information of light receiving element 141, laser unit 104 irradiates laser light LB onto the surface of photoconductor drum 102. Here, the surface of the photoconductor drum 102 is negatively charged by an electrostatic charger 103. When the photoconductor drum 102 is irradiated with laser light LB from a laser unit 104, the photoconductor drum 102 is exposed, and the potential of the irradiated portion approaches 0. Therefore, in the area corresponding to the image portion of the document, the surface potential of the photoconductor drum 102 approaches 0 in accordance with the density of the image, and an electrostatic latent image is formed. As the photoconductor drum 102 rotates, the electrostatic latent image attracts toner at a position opposite the developing device 105, forming a toner image. When the toner image is formed, paper is supplied from paper feed cassettes 142 and 143 to a conveying system 144. The paper is aligned by registration rollers 146 and then fed between the transfer charger 106 and the photoconductor drum 102. The toner image on the photoconductor drum 102 is then transferred to the paper. The paper onto which the toner image has been transferred is transported to a pair of fixing rollers 147. In the pair of fixing rollers 147, the paper is pressurized and heated, and the toner image is fixed onto the paper. The toner of the embodiment has excellent low-temperature fixing properties. Therefore, fixing can be performed at, for example, about 140 to 170°C. After fixing, the paper is discharged onto a paper discharge tray 150 via a pair of paper discharge rollers 148. Meanwhile, the toner remaining on the surface of the photoconductor drum 102 without being transferred to the paper is removed by a cleaning device 107. The toner is then returned to the developing device 105 by a recovery mechanism 110 and reused. In the image forming apparatus shown in FIG. 1, when the toner in the developing device 105 is consumed, the toner of the embodiment is newly replenished as fresh toner from a replenishing container 108.

[0073] The developing device 105 will be described with reference to FIGS. The developing device 105 has a recovery mechanism 110 that recovers toner for reuse; a developing container 111 in which a developer including the toner of the embodiment is stored; a developing roller 112 that is rotatably arranged in the developing container 111; a first partition wall 114 and a second partition wall 115 that form a first chamber 116, a second chamber 117, and a third chamber 118 in the developing container 111; a first mixer 120 that is arranged in the first chamber 116; a second mixer 121 that is arranged in the second chamber 117; a third mixer 122 that is arranged in the third chamber 118; a fresh toner receiving section 123 that receives fresh toner supplied from a refill container; a recycled toner receiving section 124; and a toner concentration detector 129.

[0074] The developing device 105 is connected to the cleaning device 107 via a recovery mechanism 110. In the developing device 105, the recovery mechanism 110 is an auger to which the recycled toner is transported. However, the recovery mechanism 110 is not limited to an auger. The cleaning device 107 may be a cleaning blade or a cleaning brush. The developing roller 112 is disposed in a position facing the lower surface of the photosensitive drum. The developing roller 112 supplies developer to the photosensitive drum by rotating.

[0075] A first communication portion 125 is formed on the first end side of the first partition wall 114. A second communication portion 126 is formed on the second end side of the first partition wall 114. A third communication portion 127 and a fourth communication portion 128 are formed in the second partition wall 115. The inside of the developing container 111 is divided into a first chamber 116, a second chamber 117, and a third chamber 118 by a first partition wall 114 and a second partition wall 115. The first chamber 116, the second chamber 117, and the third chamber 118 are formed approximately in parallel along the axial direction of the photosensitive drum 102. Here, on the paper, the direction from the second communication portion 126 to the first communication portion 125 in the first partition wall 114 is defined as a first direction. Also, the direction opposite to the first direction, i.e., the direction from the first communication portion 125 to the second communication portion 126, is defined as a second direction.

[0076] The first mixer 120 rotates to agitate and transport the developer in a first direction and supply it to the developing roller 112. The second mixer 121 and the third mixer 122 agitate and transport the developer in a second direction and send it to the upstream side of the first mixer 120. The second mixer 121 and the third mixer 122 are rotationally driven by a driving means. In the developing device 105, the driving means includes a driving motor 162 as a single driving source, and a driving gear 163 rotated by the driving motor 162. The driving gear 163 is connected to the rotating shaft 151 of the third mixer 122 via a large-diameter power transmission gear 164. In addition, the rotating shaft 121a of the second mixer 121 is connected to the large-diameter power transmission gear 164 via a small-diameter power transmission gear 165.

[0077] In the developing device 105 having the configuration described above, the developer transport speed by the third mixer 122 is lower than the developer transport speed by the second mixer 121. Therefore, the developer transport time by the third mixer 122 is longer than the developer transport time by the second mixer 121. In another embodiment, the second and third mixers 121, 122 may be rotated and driven separately by a plurality of drive motors with different rotation speeds. Also, the third mixer 122 may be provided with a reverse feed blade that transports the collected toner in a direction opposite to the second direction. Whichever method is adopted, the transport speed of the collected toner by the third mixer 122 can be made lower than the transport speed of the developer by the second mixer 121.

[0078] Next, the developing operation of the developing device 105 will be described with reference to FIGS. In the developing container 111, the developer is stirred and transported in a first direction by the rotation of the first mixer 120, and is supplied to the developing roller 112. Thereafter, the developer is supplied to the electrostatic latent image on the photoconductor drum 102 by the rotation of the developing roller 112, and the electrostatic latent image is visualized.

[0079] The developer discharged from the first mixer 120 is guided into the second chamber 117 via the first communication portion 125. Thereafter, in the second chamber 117, the developer is transported in the direction of the arrow (second direction) by the rotation of the second mixer 121. The developer discharged by the second mixer 121 is sent to the upstream side of the first mixer 120 via the second communication portion 126, and is transported so as to circulate between the first mixer 120 and the developer.

[0080] A portion of the developer transported by the second mixer 121 is sent from the third communication part 127 into the third chamber 118 and transported in the direction of the arrow (second direction). The developer is sent again into the second chamber 117 from the fourth communication part 128 and is agitated and transported by the second mixer 121. The developer is then sent to the upstream side of the first mixer 120 via the second communication part 126. Here, the toner concentration of the developer stirred and transported by the second mixer 121 is detected by a toner concentration detector 129. When the toner concentration detected by the toner concentration detector 129 falls below a predetermined value, the toner of the embodiment is replenished from the replenishing container 108. This toner falls into a fresh toner receiving portion 123 of the developing container 111. The fresh toner is stirred and transported in the direction of the arrow (second direction) by the rotation of the second mixer 121, and is sent to the upstream side of the first mixer 120.

[0081] The recovered toner recovered from the cleaning device 107 by the recovery mechanism 110 falls into the recycled toner receiving section 124. The recovered toner is transported in the second direction by the rotation of the third mixer 122. Here, the developer guided from the third communicating section 127 into the third chamber 118 is once stirred and transported toward the recycled toner receiving section 124 side as shown by the arrow a by the rotation of the reverse feed blade 153 of the third mixer 122. Thereafter, the developer together with the recovered toner is stirred and transported in the second direction as shown by the arrow b by the rotation of the forward feed blade 152. The recovered toner is sent to the upstream side of the first mixer 120 via the fourth communicating section 128 and the second communicating section 126 in this order. Some of the developer and recovered toner are sent downstream in the transport direction without being sent into the second chamber 117 through the fourth communicating portion 128. Such developer and recovered toner are sent backwards by the rotation of the reverse feed blade 155 and returned to the fourth communicating portion 128, and are sent to the second chamber 117 through the fourth communicating portion 128.

[0082] Conventionally, when a developer containing a toner is reused, the external additives tend to peel off from the toner base particles due to physical stress, causing noticeable soft caking, which leads to problems such as a decrease in the transportability of the developer, and a decrease in the charge amount and scattering amount of the toner. In contrast, the toner of the embodiment has excellent storage stability in a high-temperature environment even when reused, and the charge amount is sufficiently maintained. Therefore, the charge amount and scattering amount of the toner are sufficiently maintained, and good development is performed.

[0083] FIG. 4 shows an example of an image forming apparatus to which a developer containing the toner of the embodiment is applied. The image forming apparatus shown in Fig. 4 is a type that fixes a toner image. However, the image forming apparatus according to the embodiment is not limited to this type. The image forming apparatus according to the other embodiment may be, for example, an inkjet type. The image forming apparatus 1 shown in Fig. 4 is a four-tandem color copier MFP. The image forming apparatus 1 includes a scanner unit 2, a paper discharge unit 3, a paper feed cassette 4, an intermediate transfer belt 10, four image forming stations 11Y, 11M, 11C, and 11K arranged along the running direction S of the intermediate transfer belt 10, a secondary transfer roller 27, a fixing device 30, and a manual feed mechanism 31.

[0084] The intermediate transfer belt 10 is wound around and supported by a driven roller 20 and a backup roller 21. In addition to the driven roller 20 and the backup roller 21, a desired tension is applied to the intermediate transfer belt 10 by a first tension roller 22, a second tension roller 23, and a third tension roller 24.

[0085] The image forming stations 11Y, 11M, 11C, and 11K each have a photoconductor drum 12Y, 12M, 12C, and 12K in contact with the intermediate transfer belt 10, respectively. Arranged around the photoconductor drums 12Y, 12M, 12C, 12K are electrostatic chargers 13Y, 13M, 13C, 13K; developing devices 14Y, 14M, 14C, 14K; photoconductor cleaning devices 16Y, 16M, 16C, 16K; and primary transfer rollers 18Y, 18M, 18C, 18K.

[0086] The electric chargers 13Y, 13M, 13C, and 13K negatively charge the surfaces of the photoconductor drums 12Y, 12M, 12C, and 12K. Between the electric chargers 13Y, 13M, 13C, and 13K and the developing devices 14Y, 14M, 14C, and 14K, the laser exposure device 17 irradiates the photoconductor drums 12Y, 12M, 12C, and 12K with exposure light. Then, electrostatic latent images are formed on the photoconductor drums 12Y, 12M, 12C, and 12K. The developing devices 14Y, 14M, 14C, and 14K each have a two-component developer consisting of yellow (Y), magenta (M), cyan (C), and black (K) toner and a carrier. The developing devices 14Y, 14M, 14C, and 14K supply the toner to the electrostatic latent images on the photoconductor drums 12Y, 12M, 12C, and 12K, respectively. In this manner, the image forming stations 11Y, 11M, 11C, and 11K form monochrome images of yellow (Y), magenta (M), cyan (C), and black (K), respectively.

[0087] The primary transfer rollers 18Y, 18M, 18C, and 18K are provided on the intermediate transfer belt 10 at positions facing the photoconductor drums 12Y, 12M, 12C, and 12K, respectively. The primary transfer rollers 18Y, 18M, 18C, and 18K are used to primarily transfer the toner images on the photoconductor drums 12Y, 12M, 12C, and 12K onto the intermediate transfer belt 10. The primary transfer rollers 18Y, 18M, 18C, and 18K are each a conductive roller, and a primary transfer bias voltage is applied to each of the primary transfer rollers 18Y, 18M, 18C, and 18K.

[0088] The secondary transfer roller 27 is disposed at a transfer position where the intermediate transfer belt 10 is supported by the backup roller 21. The backup roller 21 is a conductive roller. A predetermined secondary transfer bias is applied to the backup roller 21. When a sheet of paper to be printed passes between the intermediate transfer belt 10 and the secondary transfer roller 27, the toner image on the intermediate transfer belt 10 is secondarily transferred onto the sheet of paper. After the secondary transfer is completed, the intermediate transfer belt 10 is cleaned by a belt cleaner 10a.

[0089] The paper feed cassette 4 is provided below the laser exposure device 17. The paper feed cassette 4 supplies the sheet paper P1 toward the secondary transfer roller 27. Between the paper feed cassette 4 and the secondary transfer roller 27, a pickup roller 4a, a separation roller 28a, a conveyance roller 28b, and a registration roller pair 36 are provided. The manual feed mechanism 31 is provided on one side of the image forming apparatus 1. The manual feed mechanism 31 is for manually feeding the sheet paper P2. In the manual feed mechanism 31, a manual feed pickup roller 31b and a manual feed separation roller 31c are provided between a manual feed tray 31a and a pair of registration rollers 36.

[0090] A media sensor 39 that detects the type of sheet paper is disposed on the vertical transport path 35 along which the sheet paper is transported from the paper feed cassette 4 or the manual feed tray 31a. The image forming apparatus 1 can control the transport speed, transfer conditions, fixing conditions, etc. of the sheet paper based on the detection results of the media sensor 39. The sheet paper is transported along the vertical transport path 35 through a pair of registration rollers 36 and a secondary transfer roller 27 to the fixing device 30.

[0091] The fixing device 30 has a fixing belt 53 wound around a pair of a heating roller 51 and a driving roller 52, and an opposing roller 54 disposed opposite the heating roller 51 with the fixing belt 53 interposed therebetween. The fixing device 30 can heat the fixing belt 53 at a portion in contact with the heating roller 51. The fixing device 30 then applies heat and pressure to the sheet paper onto which the toner image has been transferred between the fixing belt 53 and the opposing roller 54, thereby fixing the toner image to the sheet paper. The toner of the embodiment has excellent low-temperature fixing properties, and can be fixed at temperatures of, for example, about 140 to 170°C.

[0092] A gate 33 is provided downstream of the fixing device 30. The sheet paper is distributed to the discharge rollers 41 or the re-conveying unit 32. The sheet paper distributed to the discharge rollers 41 is discharged to the discharge section 3. On the other hand, the sheet paper distributed to the re-conveying unit 32 is guided again toward the secondary transfer roller 27.

[0093] In the image forming apparatus 1 shown in Fig. 4, the image forming station 11Y has a photoconductor drum 12Y and a process member integrally, and is provided so as to be detachable from the main body of the image forming apparatus. The process members include a charger 13Y, a developing device 14Y, and a photoconductor cleaning device 16Y. However, in other embodiments, the image forming stations 11Y, 11M, 11C, and 11K may be detachable from the image forming apparatus individually, or may be detachable from the image forming apparatus as an integrated image forming unit 11.

[0094] The toner of the embodiment may be applied to an image forming apparatus in which the developing device 14Y of the image forming apparatus shown in Fig. 4 is modified. Fig. 5 shows an example of a modified developing device that can be applied to the image forming apparatus of Fig. 4. The developing device 64Y shown in FIG. 5 contains a two-component developer consisting of yellow toner and a carrier. The developing device 64Y has a toner concentration sensor Q. The toner concentration sensor Q detects a decrease in toner concentration. When the developing device 64Y detects a decrease in concentration, it replenishes yellow toner from a toner cartridge (not shown). In this way, the developing device 64Y can maintain a constant toner concentration. In addition, the developing device 64Y can be replenished with carrier from a toner cartridge (not shown) via a developer supply port 64Y1, and the developing device 64Y can discharge the developer by overflow from a developer discharge port 64Y2 in an amount equal to the amount of developer replenished. In this way, in the developing device 64Y, the amount of developer is maintained constant, and old, deteriorated carrier is gradually replaced with new carrier. Like developing device 14Y, developing devices 14M, 14C, and 14K in FIG. 4 may be modified to developing devices 64M, 64C, and 64K (not shown) similar to developing device 64Y, except that magenta toner, cyan toner, and black toner, respectively, are used instead of yellow toner.

[0095] The toner according to at least one of the embodiments described above has excellent low-temperature fixability, and even when reused, has excellent storage stability in a high-temperature environment, and sufficiently maintains the charge amount. EXAMPLES

[0096] The following examples are provided to more specifically explain the embodiments.

[0097] The preparation of the ester waxes A1 to A12 and B1 to B8 of the examples will be described below. Into a four-neck flask equipped with a stirrer, a thermocouple, and a nitrogen inlet tube, 80 parts by mass of at least three or more long-chain alkyl carboxylic acids and 20 parts by mass of at least three or more long-chain alkyl alcohols were added. Under a nitrogen stream, an esterification reaction was carried out at 220°C to obtain a reaction product. A mixed solvent of toluene and ethanol was added to the obtained reaction product to dissolve the reaction product. Furthermore, an aqueous sodium hydroxide solution was added to the flask and stirred at 70°C for 30 minutes. After standing for another 30 minutes, the contents of the flask were separated into an organic layer and an aqueous layer, and the aqueous layer was removed from the contents. Thereafter, ion-exchanged water was added to the flask and stirred at 70°C for 30 minutes. The flask was left standing for 30 minutes, the contents in the flask were separated into an aqueous layer and an organic layer, and the aqueous layer was removed from the contents. This operation was repeated five times. The solvent was distilled off from the organic layer of the contents in the flask under reduced pressure conditions to obtain an ester wax A1. Ester Waxes A2 to A12 were obtained in the same manner as Ester Wax A1, except that the types and amounts of long-chain alkyl carboxylic acid and long-chain alkyl alcohol used were changed. Ester Waxes B1 to B8 were also obtained by the same procedure.

[0098] The long-chain alkyl carboxylic acids used were as follows: Palmitic acid (C 16 H 32 O2) Stearic acid (C 18 H 36 O2) Arachidic acid (C 20 H 40 O2) Behenic acid (C 22 H 44 O2) Lignoceric acid (C 24 H 48 O2) Cerotin acid (C 26 H 52 O2) Montanic acid (C 28 H 56 O2)

[0099] The long-chain alkyl alcohols used were as follows: Palmityl alcohol (C 16 H 34 O) Stearyl alcohol (C 18 H 38 O) Arachidyl alcohol (C 20 H 42 O) Behenyl alcohol (C 22 H 46 O) Lignoceryl alcohol (C 24 H 50 O) Seryl alcohol (C 26 H 54 O) Montanyl alcohol (C 28 H 58 O)

[0100] The toner of Example 1 was prepared as follows. First, the raw materials of the toner base particles were put into a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) and mixed. The mixture of raw materials of the toner base particles was then melted and kneaded in a twin-screw extruder. After cooling the melted and kneaded product, it was coarsely pulverized in a hammer mill. The coarsely pulverized product was then finely pulverized in a jet pulverizer. The finely pulverized product was classified to obtain toner base particles. The composition of the raw materials for the toner base particles is shown below. Crystalline polyester resin 5 parts by mass Amorphous polyester resin 85 parts by weight Ester Wax A1 5 parts by weight Carbon black 4.5 parts by weight Charge control agent 0.5 parts by weight

[0101] Next, the temperature of the Henschel mixer with a temperature control function was set to 25°C. After the toner base particles were added to the stirring section, 0.5 parts by mass of titanium oxide was added to 100 parts by mass of the toner base particles, and the mixture was stirred for 6 minutes at 25°C and 2500 rpm. After that, the stirring was stopped, and 0.45 parts by mass of silica A was added to 100 parts by mass of the toner base particles, and the mixture was stirred for 360 seconds at 25°C and 2500 rpm. The stirring was stopped again, and 0.75 parts by mass of silica B and other necessary external additives were added to 100 parts by mass of the toner base particles, and the mixture was further stirred for 360 seconds at 25°C and 2500 rpm, to obtain the toner of Example 1.

[0102] The toners of Examples 2 to 23 and Comparative Examples 1 to 22 were produced as follows. First, regarding the composition of the raw materials for the toner base particles, the toner base particles of Examples 2 to 23 and Comparative Examples 1 to 22 were produced in the same manner as in Example 1, except that ester wax A2 to A12 and B1 to B8 were used instead of ester wax A1 as shown in Tables 1, 2, 3, and 4. Next, the average primary particle diameter D of silica A 50 (r A ), the average primary particle size of silica B D 50 (r B ), silica A content w A , silica B content w B As shown in each column of Tables 1, 2, 3, and 4, and the external addition conditions of silica A and silica B were changed as shown in Tables 5, 6, 7, and 8, the external additives were mixed with the toner base particles of each example in the same manner as in Example 1, to produce the toners of Examples 2 to 23 and Comparative Examples 1 to 22.

[0103] [Table 1]

[0104] [Table 2]

[0105] [Table 3]

[0106] [Table 4]

[0107] [Table 5]

[0108] [Table 6]

[0109] [Table 7]

[0110] [Table 8]

[0111] The method for measuring the residual ratios X and Y will now be described. The residual rate X and the residual rate Y were calculated according to the following formula. Survival rate X=(N a2 / N a1 )×100...Equation (1) Survival rate Y=(N b2 / N b1 )×100...Equation (2)

[0112] In formula (1), N a1 is the number of silica A particles attached to the toner of each example; N a2 is the number of silica A particles attached measured on particles z obtained by the following method Z. In formula (2), N b1 is the number of attached particles of silica B measured for the toner of each example; N b2 is the number of silica particles B attached, measured for particles z obtained by the following method Z. N a1, N a2 , N b1 , N b2 The number of silica particles attached was counted in scanning electron microscope (SEM) images. Specifically, observations were performed at a magnification of 50,000 times using an SEM (ZEISS "ULTRA55"). A frame of 1 μm in length and width (1 μm 2 ) was set, and the number of silica particles present within this frame was measured for each type of silica.

[0113] Method Z: 11g of toner from each example, 56.8g of ion-exchanged water, and 12.8g of surfactant were added to a 100ml beaker, mixed, and stirred with a magnetic stirrer until there was no toner layer on the liquid surface, to prepare a dispersion. This is the toner dispersion process. Saraya's "Yashinomi detergent" was used as the surfactant. Next, the dispersion was subjected to ultrasonic treatment at 20° C., 1000 Hz, and 10 minutes using an ultrasonic cleaner (ASONE US-1R). This is the toner impact process. After this impact process, the dispersion was poured into two centrifuge tubes, and ion-exchanged water was added to each tube to make the volume 45 ml. The centrifuge tubes were centrifuged at 20°C, 1000 rpm, and 15 minutes. The centrifuge used was AS ONE's "HSIANGTAI CN-2060". After that, the supernatant liquid in the centrifuge tube was removed by decantation, and ion-exchanged water was added to make the volume 45 ml, and the mixture was stirred again. This procedure was repeated two more times. The external additives that had been removed were then separated, and filtered and washed by adding 100 ml of ion-exchanged water. ADVANTEC GC90 filter paper was used for the filtration. After washing, the mixture was vacuum-dried at 30°C for 8 hours to obtain particles z.

[0114] The crystalline polyester resins and non-crystalline polyester resins used in the examples are as follows. Crystalline polyester resin (mass average molecular weight: 9.5×10 3 , melting point: 100℃) Amorphous polyester resin (mass average molecular weight: 20×10 3 , Melting temperature: 110℃)

[0115] The method for measuring the melting point of the crystalline polyester resin will be described below. The crystalline polyester resin was measured using a DSC Q2000 (manufactured by TA Instruments) under the following measurement conditions: Sample size: 5 mg. Lid and pan: Alumina. Heating rate: 10℃ / min. Measurement method: The sample was heated from 20°C to 200°C. Then, the sample was cooled to below 20°C. The sample was heated again, and the maximum endothermic peak temperature measured in the temperature range of about 75 to 120°C was determined as the melting point of the crystalline polyester resin.

[0116] The method for measuring the melting temperature of the non-crystalline polyester resin will be described. The toner of each example was pressed with a pressure machine to form it into pellets. The melting temperature of the amorphous polyester resin of the pellets was measured using a flow tester "CFT-500D (manufactured by Shimadzu Corporation)" under the following conditions. Measurement start temperature: 30℃ End of measurement temperature: 200℃ Load: 10kgf Heating rate: 10℃ / min In the flow tester, the temperature corresponding to the midpoint (1 / 2) between the flow start temperature at which melting and flowing began and the flow end temperature at which the entire sample melted and flowed was defined as the melting temperature.

[0117] A method for measuring the carbon number distribution (proportion of ester compounds with each carbon number) of ester compounds constituting the ester wax will be described. 0.5 g of the toner of each example was weighed and placed in an Erlenmeyer flask. Next, 2 mL of methylene chloride was added to the Erlenmeyer flask to dissolve the toner. Furthermore, 4 mL of hexane was added to the Erlenmeyer flask to obtain a mixed liquid. The mixed liquid was filtered to separate into a filtrate and an insoluble matter. The solvent was distilled off from the filtrate under a nitrogen stream to obtain a precipitate. For this precipitate, the carbon number distribution of the ester compound in the ester wax extracted from the toner was measured.

[0118] The proportion of ester compounds with each carbon number was measured using an FD-MS "JMS-T100GC (manufactured by JEOL Ltd.)" under the following measurement conditions. Sample concentration: 1 mg / ml (solvent: chloroform). Cathode voltage:-10kv. Spectral recording interval: 0.4 s. Measurement mass range (m / z): 10 to 2000.

[0119] The total ionic strength of the ester compounds with each carbon number obtained in the measurement was set to 100. The relative value of the ionic strength of the ester compound with each carbon number to the total was calculated. The relative value was taken as the proportion of the ester compound with each carbon number in the ester wax. The number of carbon atoms in the ester compound with the maximum relative value was designated as C l It was decided.

[0120] The analytical methods for the first and second monomer groups will be described. Methanolysis reaction was carried out for 3 hours at 70°C for 1 g of each ester wax. Mass spectrometry was carried out on the products after the methanolysis reaction to determine the content of long-chain alkyl carboxylic acids with each carbon number and the content of long-chain alkyl alcohols with each carbon number.

[0121] A method for measuring the carbon number distribution (proportion of carboxylic acids with each carbon number) of the carboxylic acids constituting the first monomer group will be described. The proportion of carboxylic acids with each carbon number was measured using an FD-MS "JMS-T100GC (manufactured by JEOL Ltd.)" under the following measurement conditions. Sample concentration: 1 mg / ml (solvent: chloroform). Cathode voltage:-10kv. Spectral recording interval: 0.4 s. Measurement mass range (m / z): 10 to 2000.

[0122] The sum of the ionic intensities of the carboxylic acids with each carbon number obtained in the measurement was set to 100. The relative values ​​of the ionic intensities of the carboxylic acids with each carbon number to the total were calculated. The relative values ​​were taken as the proportions of the carboxylic acids with each carbon number in the ester wax. The number of carbon atoms in the carboxylic acid with the maximum relative value was designated as C n It was decided.

[0123] A method for measuring the carbon number distribution (proportion of alcohols with each carbon number) of the alcohols constituting the second monomer group will be described. The proportion of alcohols with each carbon number was measured using an FD-MS "JMS-T100GC (manufactured by JEOL Ltd.)" under the following measurement conditions. Sample concentration: 1 mg / ml (solvent: chloroform). Cathode voltage:-10kv. Spectral recording interval: 0.4 s. Measurement mass range (m / z): 10 to 2000.

[0124] The sum of the ion intensities of the alcohols with each carbon number obtained in the measurement was set to 100. The relative value of the ion intensity of the alcohol with each carbon number to the total was calculated. The relative value was taken as the proportion of the alcohol with each carbon number in the ester wax. The carbon number in the alcohol with the carbon number that gave the maximum relative value was designated as C m It was decided.

[0125] The ester waxes A1 to A12 and B1 to B8 used in each example will be explained below. For all of the ester waxes A1 to A12, the carbon number C of the ester compound with the maximum content l is 44, and the carbon number C of the carboxylic acid, which is the maximum content in the first monomer group, is n is 22, and the carbon number C of the alcohol with the maximum content in the second monomer group is m was 20. Moreover, for the ester waxes A1 to A12, the carbon number distribution of the ester wax had only one maximum peak in the region of 43 or more carbon atoms. The properties of the ester waxes A1 to A12 obtained from the results of the mass distribution measurements are shown in Table 9. The properties of the ester waxes B1 to B8 are shown in Table 10.

[0126] [Table 9]

[0127] [Table 10]

[0128] In Tables 9 and 10, a1 is the number [mass%] of types of carboxylic acids in the first monomer group. a2 is the number [mass%] of types of alcohols in the second monomer group. b1 is the total ratio [mass%] of carboxylic acids having 18 or less carbon atoms to 100 mass% of the first monomer group. b2 is the total ratio [mass%] of alcohols having 18 or less carbon atoms to 100 mass% of the second monomer group. c1 is the ratio [mass%] of the number of carbon atoms C to 100 mass% of the first monomer group. n c2 is the ratio of the number of carbon atoms C to 100% by mass of the second monomer group. m is the percentage of alcohol by mass.

[0129] Average primary particle size D of Silica A and Silica B 50 The measurement method will be explained. A laser diffraction particle size distribution analyzer (Shimadzu Corporation (SALD7000)) was used.

[0130] The developer of the embodiment will be described. 8.5 parts by mass of the toner of each example was mixed with 100 parts by mass of the ferrite carrier in a Turbula mixer to obtain a developer of each example. The surface of the ferrite carrier was coated with a silicone resin having an average particle size of 40 μm.

[0131] The method for evaluating the low-temperature fixability will be described. The developer of each example was contained in a toner cartridge. This toner cartridge was placed in an image forming apparatus for evaluating low-temperature fixability. The image forming apparatus for evaluating low-temperature fixability was a commercially available e-studio5018A (manufactured by Toshiba Tec) that was modified so that the fixing temperature could be changed and set in increments of 0.1°C from 100°C to 200°C. Using the image forming apparatus for evaluating low-temperature fixability, the fixing temperature was set to 150°C, and the toner adhesion amount was set to 1.5 mg / cm. 2 Ten solid images of this type were obtained. If no offset or image peeling due to non-fixing occurred in any of the 10 solid images, the set temperature was lowered by 1°C, and a solid image was obtained in the same manner as above. This operation was repeated to determine the lowest fixing temperature at which image peeling did not occur in the solid image, and this lowest temperature was determined as the minimum fixing temperature of the toner. When the minimum fixing temperature was 120°C or lower, the low-temperature fixing property of the toner was evaluated as pass (◯). When the minimum fixing temperature was higher than 120°C, the low-temperature fixing property of the toner was evaluated as fail (×).

[0132] The method for evaluating the storage stability in a high-temperature environment will be described. If the evaluation results for all four items below, "heat resistance," "transportability," "toner scattering," and "image density," were passed (◯), the storage stability in a high-temperature environment was evaluated as excellent.

[0133] The evaluation method for "heat resistance" will be described. The toner of each example was left to stand at 55°C for 10 hours. After being left to stand at 55°C for 10 hours, 15 g of the toner was sieved through a mesh with 0.07 mm openings, and the toner remaining on the mesh was weighed. The smaller the amount of toner remaining on the mesh, the less coagulation there was and the better the heat resistance. When the amount of toner remaining on the mesh was 3 g or less, the heat resistance of the toner was evaluated as pass (○). When the amount of toner remaining on the mesh was more than 3 g, the heat resistance of the toner was evaluated as fail (×).

[0134] The method for evaluating the "transportability" will be described. Using a commercially available e-studio5018A (manufactured by Toshiba Tec), the temperature of the developer Dc-Sl was adjusted to saturate at 47°C. Then, while operating the recycle system, 30,000 double-sided prints of A4 size images with a print rate of 8% were printed in a hot and humid environment, and the temperature of the developer Dc-Sl was adjusted to maintain 47°C by adjusting the airflow of the cooling fan. The image density difference after printing 30,000 sheets was measured with a densitometer (X-Rite's "eXact"). The image density was measured by measuring the image density of a solid image every 1 cm in the main scanning direction with a densitometer, and the difference between the maximum and minimum values ​​of all these values ​​was calculated. When the image density difference was less than 0.8, the developer transportability was evaluated as pass (◯), and when the image density difference was 0.8 or more, the developer transportability was evaluated as fail (×).

[0135] The method for evaluating "toner scattering" will be described. Using a commercially available e-studio5018A (manufactured by Toshiba Tec), a document with a print rate of 8.0% was continuously copied onto 200,000 sheets of A4 paper. After that, the toner accumulated under the magnetic roller of the developing unit was sucked up with a vacuum cleaner, and the amount of accumulated toner was measured as the amount of scattered toner. When the amount of scattered toner was 170 mg or less, the charge amount of the toner was evaluated as pass (○). When the amount of scattered toner was more than 170 mg, the charge amount of the toner was evaluated as fail (×).

[0136] The evaluation method for "image density" will be described. Each developer was left in a thermostatic chamber at a temperature of 10°C and a humidity of 20% for 24 hours, and then housed in a toner cartridge. This toner cartridge was placed in a commercially available e-studio5018A (manufactured by Toshiba Tec). After printing 100 sheets of a chart with a printing rate of 10%, an A4-sized solid image was printed, and the image density at the four corners and the center of the image was measured with a densitometer (X-Rite's "eXact"), and the average value of these five points was calculated. When the average value of the image density was 1.0 or more, the image density was evaluated as pass (○). When the average value of the image density was less than 1.0, the image density was evaluated as fail (×).

[0137] The evaluation results of the low temperature fixing property, heat resistance, transportability, toner scattering, and image density of each example of toner are shown in Tables 1, 2, 3, and 4. The toners of Examples 1 to 23 were excellent in low-temperature fixing property and excellent in storage stability in a high-temperature environment. The e-studio5018A is an image forming apparatus that reuses toner. Therefore, the toners of Examples 1 to 23 have excellent storage stability in a high-temperature environment even when reused, and the charge amount is sufficiently maintained. In contrast, the toners of Comparative Examples 1 to 22 did not reach the pass standards simultaneously for all of low-temperature fixability, heat resistance, transportability, toner scattering, and image density.

[0138] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0139] 1...image forming apparatus, 2...scanner section, 3...paper discharge section, 4...paper feed cassette, 10...intermediate transfer belt, 11Y, 11M, 11C, 11K...image forming station, 12Y, 12M, 12C, 12K...photoconductor drum, 13Y, 13M, 13C, 13K...electric charger, 14Y, 14M, 14C, 14K...developing device, 30...fixing device, 31...manual feed mechanism, 64Y...developing device, 101...copying machine main body, 102...photoconductor drum, 103...electric charger , 104...laser unit, 105...developing device, 106...transfer charger, 107...cleaning device, 108...supply container, 110...recovery mechanism, 111...developing container, 112...developing roller, 114, 115...first and second partition materials, 116-118...first to third chambers, 120-122...first to third mixers, 123...fresh toner receiving section, 124...recycled toner receiving section, 125-128...first to fourth communicating sections, 129...toner concentration detector.

Claims

1. The toner comprises a toner base particle and an external additive attached to the surface of the toner base particle, the toner base particles contain a crystalline polyester resin, an ester wax, and a colorant, The external additive has an average primary particle diameter D ５０ Silica A having an average primary particle diameter D ５０ and monodispersed silica B having a particle size of 90 to 150 nm; the ester wax is a condensation polymer of a first monomer group consisting of at least three or more kinds of carboxylic acids and a second monomer group consisting of at least three or more kinds of alcohols, a ratio of carboxylic acids having 18 or less carbon atoms in the first monomer group is 5% by mass or less with respect to 100% by mass of the first monomer group, a ratio of alcohols having 18 or less carbon atoms in the second monomer group is 20% by mass or less with respect to 100% by mass of the second monomer group, The maximum carbon number C in the first monomer group ｎ the ratio of the carboxylic acid is 70 to 95% by mass relative to 100% by mass of the first monomer group, The maximum carbon number C in the second monomer group ｍ The ratio of the alcohol is 70 to 90% by mass relative to 100% by mass of the second monomer group, The content of silica A is 0.1 to 0.8 parts by mass relative to 100 parts by mass of the toner base particles, The content of silica B is 0.3 to 1.2 parts by mass relative to 100 parts by mass of the toner base particles, the ratio of the content of silica B to the content of silica A is 1.0 to 5.0; The residual rate X of silica A calculated by the following formula (1) is 70% or more, The residual rate Y of silica B calculated by the following formula (2) is 30% or more, A toner, wherein the ratio of residual ratio X to residual ratio Y is 1.0 to 3.

0. Survival rate X = (N ａ２ / N ａ１ )×100 ……Formula (1) Survival rate Y = (N ｂ２ / N ｂ１ )×100 ……Formula (2) In formula (1), N ａ１ is the number of silica A particles attached to the toner; N ａ２ is the number of silica A particles attached measured on particles z obtained by the following method Z. In formula (2), N ｂ１ is the number of silica B particles attached to the toner; N ｂ２ is the number of attached silica B particles measured for particles z obtained by the following method Z. Method Z: An aqueous liquid containing the toner of the embodiment, water, and a surfactant is subjected to ultrasonic treatment under conditions of 20°C, 1000 Hz, and 10 minutes, and then centrifuged under conditions of 20°C, 1000 rpm, and 15 minutes, the separated external additives are removed, and then the resulting particles are dried and designated as particles z.

2. The toner according to claim 1 , wherein the toner base particles further comprise a non-crystalline polyester resin.

3. 3. The toner according to claim 1, wherein the total content of the silica A and the silica B is 0.5 to 1.7 parts by mass per 100 parts by mass of the toner base particles.

4. A toner cartridge containing the toner according to any one of claims 1 to 3.

5. An image forming apparatus containing the toner according to any one of claims 1 to 3.

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