Toner, developer, toner storage unit, image formation apparatus and image formation method

Abstract

To provide toner excellent in low temperature fixability and capable of achieving both filming control in high temperature and high humidity and releasability during fixation.SOLUTION: Toner includes toner particles including a polyester resin, a mold lubricant and an aromatic petroleum resin. The acid number of the toner is 6 mgKOH / g or more and 12 mgKOH / g or less; and when observing the cross section of the toner particle by a scanning electron microscope, the aromatic petroleum resin exists in the interface part of the domain of the mold lubricant, and in the matrix of the polyester resin, the domain of the aromatic petroleum resin exists in a dispersed state.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a toner, a developer, a toner storage unit, an image forming apparatus, and an image forming method. [Background technology]

[0002] Conventionally, in electrophotographic devices, electrostatic recording devices, and the like, electric latent images or magnetic latent images are visualized by electrostatic latent image developing toner (also referred to as "toner" in the present invention). For example, in electrophotography, an electrostatic latent image is formed on an electrostatic latent image carrier, and then the electrostatic latent image is developed with toner to form a toner image. The toner image is usually transferred onto a recording medium such as paper and fixed by a method such as heating.

[0003] In recent years, there has been a demand for low-temperature fixing of toners in order to save energy by reducing the energy required for fixing. Furthermore, due to the demand for faster speeds and higher image quality of image forming apparatuses, coupled with the diversification of the purposes of use of image forming apparatuses, there is an increasing demand for low-temperature fixing of toners. As a method for low-temperature fixing of toners, a technique using a combination of an amorphous polyester resin and a crystalline polyester resin is known.

[0004] For example, a pulverized toner has been disclosed that aims to provide a toner with excellent grindability during production and excellent fixing stability, and is produced by pulverizing and classifying a composition in which a styrene resin with a mass average molecular weight (Mw) of more than 3,000 is internally added to a mixture of a binder resin and a colorant (see, for example, Patent Document 1). Also, a pulverized toner has been disclosed that aims to provide a pulverized toner that can achieve both low-temperature fixing properties and heat-resistant storage stability, in which the maximum peak ratio of the polyester resin to the styrene resin measured by FT-IR has been specified (see, for example, Patent Document 2). Also, a toner has been disclosed that aims to provide a toner that can achieve both good release properties of fixed images and suppression of image density reduction during continuous printing in a low-temperature, low-humidity environment, in which the ratio of the total cross-sectional area of ​​the toner particles to the major axis of the domain of the release agent has been specified (see, for example, Patent Document 3). Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional toners, including those described in Patent Documents 1 to 3, have been known to have problems such as image defects caused by filming, in which wax or polyester resin with low heat resistance exposed on the toner surface adheres to the electrostatic latent image carrier. This problem is particularly pronounced in high-temperature, high-humidity environments, and image defects become even more pronounced when the printing area is small. Meanwhile, when the amount of wax used is reduced, hot offset resistance becomes an issue. Achieving both filming suppression and hot offset resistance in such high-temperature, high-humidity environments has been an issue. An object of the present invention is to provide a toner that has excellent low-temperature fixability, and is capable of suppressing filming in a high-temperature, high-humidity environment while also providing good releasability during fixation. [Means for solving the problem]

[0006] The toner of the present invention that solves the above problems is as described below. A toner comprising toner particles containing a polyester resin, a release agent, and an aromatic petroleum resin, the toner has an acid value of 6 mgKOH / g or more and 12 mgKOH / g or less; When a cross section of the toner particle is observed with a scanning electron microscope, the aromatic petroleum resin is present at the interface between domains of the release agent, and the domains of the aromatic petroleum resin are present in a dispersed state in a matrix of the polyester resin. A toner characterized by: [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a toner that has excellent low-temperature fixing properties, and is capable of suppressing filming in a high-temperature, high-humidity environment while also providing good releasability during fixing. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional image of a toner according to the present invention. [Figure 2] 1 is a cross-sectional image of a toner according to the present invention. [Figure 3] 1 is a schematic view showing an example of an electrophotographic developing device according to the present invention. [Figure 4] FIG. 2 is a schematic view showing an example of a developing device used in the present invention. [Figure 5] 4 is a diagram showing an example of an image forming apparatus having the developing device of FIG. 3. [Figure 6] FIG. 10 is a diagram illustrating another example of an image forming apparatus used in the present invention. [Figure 7] FIG. 10 is a diagram illustrating another example of an image forming apparatus used in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The toner of the present invention will be described in detail below.

[0010] (toner) The toner of the present invention is a toner containing toner particles containing a polyester resin, a release agent, and an aromatic petroleum resin. The acid value of the toner is 6 mgKOH / g or more and 12 mgKOH / g or less. Furthermore, when the cross section of the toner particle is observed with a scanning electron microscope, as shown in Figures 1 and 2, the aromatic petroleum resin is present at the interface between the domains of the release agent, and the domains of the aromatic petroleum resin are present in a dispersed state in the matrix of the polyester resin.

[0011] When release agent particles are present alone in a polyester resin (hereinafter sometimes referred to as "binder resin"), the release agent present on the toner surface or a fine toner powder with a high release agent component contaminates the carrier and electrostatic latent image carrier, causing toner scattering due to a decrease in charge caused by carrier spent, worsening background scumming, and filming on the electrostatic latent image carrier. In particular, when continuous printing is performed under conditions of a small image area and low toner balance, problems such as filming on the electrostatic latent image carrier due to the release agent component adhering to the electrostatic latent image carrier have occurred.

[0012] In the toner of the present invention, by having an aromatic petroleum resin present around the release agent particles, or by having a portion of the aromatic petroleum resin present alone, adhesion of the release agent components to the electrostatic latent image carrier during actual image formation can be suppressed, and carrier spent and filming on the electrostatic latent image carrier can be suppressed.

[0013] <Binder resin> The toner particles of the present invention contain a polyester resin as a binder resin. The weight average molecular weight (Mw) is preferably 7,000 to 10,000, more preferably 7,500 to 9,500, and even more preferably 8,000 to 9,000. The weight average molecular weight (Mw) / number average molecular weight (Mn) ratio is preferably 5 or less, and more preferably 4 or less.

[0014] The polyester resin used in the present invention may be any of those obtained by a polycondensation reaction between a generally known alcohol and an acid. For example, examples of alcohols include diols such as polyethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-propylene glycol, neopentyl glycol, and 1,4-butenediol; etherified bisphenols such as 1,4-bis(hydroxymethyl)cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylenated bisphenol A; and saturated or unsaturated bisphenols having 3 to 22 carbon atoms. dihydric alcohol units substituted with hydrocarbon groups, other dihydric alcohol units, sorbitol, 1,2,3,6-hexanetetrol, 1,4-salbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, and other trihydric or higher alcohol monomers.

[0015] Examples of carboxylic acids used to obtain polyester resins include monocarboxylic acids such as palmitic acid, stearic acid, and oleic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, and malonic acid, divalent organic acid monomers obtained by substituting these with saturated or unsaturated hydrocarbon groups having 3 to 22 carbon atoms, anhydrides of these acids, dimers of lower alkyl esters and linoleic acid, and 1,2,4-benzotriazoles. Examples of suitable carboxylic acid monomers include tricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, embolic trimer acid, and anhydrides of these acids.

[0016] <Release agent> The release agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the waxes include vegetable waxes such as carnauba wax, cotton wax, and wood wax / rice wax; animal waxes such as beeswax and lanolin; mineral waxes such as ozokerite and cerusine; and natural waxes such as petroleum waxes such as paraffin, microcrystalline, and petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax, polyethylene, and polypropylene; and synthetic waxes such as esters, ketones, and ethers can also be used.

[0017] Furthermore, fatty acid amide compounds such as 12-hydroxystearic acid amide, stearic acid amide, phthalimide anhydride, and chlorinated hydrocarbons; low-molecular-weight crystalline polymer resins, such as homopolymers or copolymers of polyacrylates as poly-n-stearyl methacrylate and poly-n-lauryl methacrylate (for example, copolymers of n-stearyl acrylate and ethyl methacrylate); and crystalline polymers having long alkyl groups in their side chains can also be used. Among these, hydrocarbon waxes such as paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, and polypropylene wax are preferred from the viewpoint of being able to suppress the occurrence of filming.

[0018] Hydrocarbon waxes have low compatibility with common polyester resins, so they tend to seep out onto the surface during fixing, providing high release properties and ensuring high gloss and low-temperature fixability. The melting point of the release agent is not particularly limited and can be appropriately selected depending on the purpose, but the melting point is preferably 80° C. or higher and 100° C. or lower. If the melting point is lower than 80° C., the heat-resistant storage stability deteriorates, and if the melting point is higher than 100° C., the low-temperature fixability deteriorates.

[0019] The content of the release agent is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 2 to 6 parts by weight, more preferably 3 to 5 parts by weight, per 100 parts by weight of the toner. If the content is less than 2 parts by weight, the release agent does not bleed to the surface during fixing, resulting in poor release properties and reduced low-temperature fixability and high-temperature offset resistance. If the content is more than 6 parts by weight, the amount of release agent precipitated on the toner surface increases, reducing the storage stability and fluidity of the toner, worsening filming on electrostatic latent image carriers and reducing the transportability of residual toner.

[0020] <Toner acid value> The toner of the present invention preferably has an acid value of 6 mgKOH / g or more and 12 mgKOH / g or less. During fixing, the acidic groups in the polyester resin and the aromatic petroleum resin described below have a moderate affinity with each other, allowing the aromatic petroleum resin to exist at the interface between the binder resin and the domains of the release agent particles. If the acid value exceeds 12 mgKOH / g, the aromatic petroleum resin becomes miscible, and the release agent particles tend to exist independently, which may result in poor filming of the electrostatic latent image carrier.If the acid value is below 6 mgKOH / g, the affinity of the aromatic petroleum resin decreases, and the release agent particles tend to exist independently, which may result in poor filming of the electrostatic latent image carrier.

[0021] The acid value of the toner is measured under the following conditions in accordance with the measurement method described in JIS K0070-1992. Sample preparation: Add 0.5 g of toner (0.3 g of ethyl acetate-soluble components) to 120 mL of toluene and dissolve by stirring at room temperature (23°C) for approximately 10 hours. Add 30 mL of ethanol to make a sample solution. The acid value can be determined in accordance with the above-mentioned JIS K0070-1992, and specifically, it is determined as follows. Titrate with a pre-standardized N / 10 caustic potassium alcohol solution, and calculate the acid value using the following formula based on the amount of potassium alcohol solution consumed. Acid value = KOH (mL) x f x 56.1 / sample mass (where f is the factor N / 10KOH)

[0022] Specifically, the acid value of the toner is determined using the following equipment under the following conditions. Measurement device: Potentiometric automatic titrator DL-53 Titrator (Mettler-Toledo) Electrode used: DG113-SC (Mettler-Toledo) Analysis software: LabX Light Version 1.00.000 Calibration of the instrument: Use a mixed solvent of 120 mL of toluene and 30 mL of ethanol. Measurement temperature: 23℃ The measurement conditions are as follows. Stirring conditions Stirring speed [%]:25 Stirring time [s]: 15 Equilibrium titration conditions Titrant: CH3ONa Concentration [mol / L]:0.1 Electrode:DG115 Measurement unit: mV Titrant drop before measurement Dripping amount [mL]: 1.0 Wait time [s]: 0 Titrant drip mode: Dynamic dE(set)[mV]:8.0 dV(min)[mL]:0.03 dV(max)[mL]:0.5 Measurement mode: equilibrium titration dE[mV]:0.5 dt[s]:1.0 t(min)[s]:2.0 t(max) [s]20.0 Recognition conditions Threshold: 100.0 Maximum rate of change only: No Range: No Frequency: None Measurement end condition Maximum dripping amount [mL]: 10.0 Electric potential: No Gradient: No After equivalence point: Yes Number of n: 1 End condition combination: No Evaluation conditions Procedure: Standard Potential 1: No Potential 2: No Suspension for reassessment: No

[0023] <Hydroxyl value of toner> The hydroxyl value of the toner of the present invention is preferably 25 mgKOH / g or more and 45 mgKOH / g or less, and more preferably 30 mgKOH / g or more and 40 mgKOH / g or less. If the hydroxyl value is higher than 45 mgKOH / g, the toner will adsorb moisture in a high-temperature, high-humidity environment, reducing the charge amount and causing abnormal images such as background scumming and toner scattering. If the hydroxyl value is lower than 25 mgKOH / g, the fixation between the resin and paper will be reduced, and low-temperature fixation and offset resistance will be reduced.

[0024] The hydroxyl value of the toner is measured under the following conditions in accordance with the measurement method described in JIS K0070-1992. Sample preparation: (1) Preparation of 0.5 mol / L potassium hydroxide titration solution Dissolve 40g of potassium hydroxide in 50ml of ion-exchanged water. Discard 10ml of the supernatant of the potassium hydroxide solution, then add methanol to make up to 1000ml. (2) Preparation of methanol-acetone mixed solution Mix 1 L of methanol and 1 L of acetone, add 1 drop of BTB reagent and 30 ml of PP indicator, then add 0.1 mol / L potassium hydroxide methanol solution until the color becomes slightly reddish-purple. (3) 5 g of toner is weighed accurately into an Erlenmeyer flask, 5 ml of a mixture of acetic anhydride and pyridine (1:4) is added using a volumetric pipette, and 25 ml of pyridine is added using a measuring cylinder. A condenser is attached to this, and the mixture is reacted in an oil bath at 98°C for 1.5 hours. (4) Add 3 ml of ion-exchanged water from the top of the condenser tube and heat in the oil bath for an additional 10 minutes. (5) Remove the Erlenmeyer flask from the oil bath and allow it to cool to room temperature. Then, rinse the condenser with acetone and remove it. (6) Add 50 ml of tetrahydrofuran using a measuring cylinder, add 10 drops of PP indicator, and titrate with the 0.5 mol / L potassium hydroxide titrant prepared in (1). Near the end point, add 25 ml of the methanol-acetone mixed solution prepared in (2) and continue titrating. The end point is the point at which a slight pink color persists for 30 seconds, and the titration volume is determined. (7) Repeat steps (3) to (6) above without a sample to perform a blank test. (8) Calculate the hydroxyl value using the following formula. Hydroxyl value = [(BA) × f × 28.05 / S] + acid value A: Titration volume of 0.5 mol / L potassium hydroxide titrant required for this test B: Titration volume of 0.5 mol / L potassium hydroxide titrant required for blank test f: Factor of 0.5 mol / L potassium hydroxide titrant ·S: Sample collection amount (g)

[0025] <Aromatic petroleum resin> The aromatic petroleum resin used in the present invention is preferably a styrene-based resin, and examples thereof include polymers of styrene and its substitution products, such as polystyrene, poly-p-styrene, and polyvinyltoluene; styrene-based copolymers such as styrene-α-methylstyrene copolymer, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer.

[0026] The glass transition temperature of the aromatic petroleum resin used in the present invention is preferably 70 to 90° C., and more preferably 75 to 85° C. If the glass transition temperature is lower than 70° C., the heat-resistant storage stability of the toner decreases, and if it is higher than 90° C., the low-temperature fixability deteriorates.

[0027] The glass transition point (Tg) in the present invention was determined by using a differential scanning calorimeter (DSC210, manufactured by Seiko Instruments Inc.) to measure 0.01 to 0.02 g of a sample into an aluminum pan, heating the sample to 150°C, and then cooling the sample from that temperature at a rate of 10°C / min to 20°C. The sample was then heated again at a rate of 10°C / min, and the glass transition point was determined as the temperature at the intersection of an extension of the baseline below the highest endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the peak apex.

[0028] The content of the aromatic petroleum resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 to 15 parts by mass, more preferably 5 to 10 parts by mass, and even more preferably 7 to 10 parts by mass, relative to 100 parts by mass of the toner. If the content is less than 5 parts by mass, the pulverizability during toner pulverization decreases, and the productivity of the pulverized toner decreases. If the content is more than 15 parts by mass, the low-temperature fixability deteriorates.

[0029] <Coloring agent> Examples of colorants include carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ochre, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Balkan fast yellow (5G, R), tartrazine lake, quinoline yellow lake, anthrazan yellow BGL, isoindolinone yellow, red iron oxide, red lead, vermilion, Cadmium Red, Cadmium Mercury Red, Antimony Vermilion, Permanent Red 4R, Para Red, Faise Red, Parachlor Orthonitroaniline Red, Lithol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belcan Fast Rubin B, Brilliant Scarlet G, Lithol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bol Daw 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkali Blue Lake, Peacock Blue Lake, Victoria Blue Lake Metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, indanthrene blue (RS, BC), indigo, ultramarine, Prussian blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green,Anthraquinone green, titanium oxide, zinc oxide, lithopone, and mixtures thereof can be used. The amount used is generally 0.1 to 80 parts by mass per 100 parts by mass of the binder resin.

[0030] <External additives> Examples of external additives include abrasives such as silica, Teflon (registered trademark) resin powder, polyvinylidene fluoride powder, cerium oxide powder, silicon carbide powder, and strontium titanate powder, fluidity-imparting agents such as titanium oxide powder and aluminum oxide powder, anti-aggregation agents, resin powders, and conductivity-imparting agents such as zinc oxide powder, antimony oxide powder, and tin oxide powder, as well as white and black fine particles of opposite polarity that can be used as developability improvers. These can be used alone or in combination, and are selected so as to provide resistance to development stresses such as idle spin.

[0031] The toner of the present invention preferably has an average circularity of 0.93 or more and 0.96 or less.

[0032] <Developer> When using a two-component developer, magnetic particles used in the magnetic carrier can be magnetite, spinel ferrites such as gamma iron oxide, spinel ferrites containing one or more metals other than iron (e.g., Mn, Ni, Zn, Mg, Cu), magnetoplumbite ferrites such as barium ferrite, or iron or alloy particles with an oxide layer on the surface. The shape may be granular, spherical, or acicular. Ferromagnetic particles such as iron are preferred when particularly high magnetization is required. Furthermore, considering chemical stability, magnetite, spinel ferrites containing gamma iron oxide, and magnetoplumbite ferrites such as barium ferrite are preferred. By selecting the type and content of ferromagnetic particles, a resin carrier with the desired magnetization can be used. The magnetic properties of the carrier in this case preferably have a magnetization strength of 30 to 150 emu / g at 1,000 oersteds.

[0033] Such a resin carrier can be produced by spraying a molten mixture of magnetic fine particles and an insulating binder resin using a spray dryer, or by reacting and curing a monomer or prepolymer in an aqueous medium in the presence of magnetic fine particles to produce a resin carrier in which magnetic fine particles are dispersed in a condensation type binder.

[0034] The chargeability can be controlled by adhering positively or negatively chargeable particles or conductive particles to the surface of the magnetic carrier, or by coating the surface with a resin. As the surface coating material, silicone resin, acrylic resin, epoxy resin, or fluorine-based resin can be used, and the coating can further include positively or negatively charged particles or conductive particles, but silicone resin and acrylic resin are preferred. The mixing ratio of the toner of the present invention and the magnetic carrier is preferably 2% by mass or more and 10% by mass or less in terms of toner concentration. The weight average particle size of the toner is preferably 2 μm or more and 10 μm or less.

[0035] The particle size of the toner is measured by various methods, for example, using a Coulter Counter Multisizer III. The measurement sample is prepared by adding the toner to be measured to an electrolyte solution containing a surfactant, dispersing the toner for 1 minute using an ultrasonic disperser, and measuring 50,000 particles. To prepare the toner of the present invention, a fixing resin, a lubricant, and optionally a colorant, and a fixing resin in which a charge control agent, lubricant, and additives are uniformly dispersed, are combined and thoroughly mixed in a mixer such as a Henschel mixer or a super mixer, and then melt-kneaded using a heat-melting kneader such as a heated roll, kneader, or extruder to thoroughly mix the materials, and then cooled and solidified, followed by fine pulverization and classification to obtain the toner. The pulverization method used here may include a jet mill method in which the toner is immersed in a high-speed air stream and collided with a collision plate to be pulverized by the energy generated, an inter-particle collision method in which toner particles collide with each other in the air stream, or a mechanical pulverization method in which the toner is supplied between a narrow gap and a rotor rotating at high speed to be pulverized.

[0036] <Image forming apparatus and image forming method> The image forming apparatus of the present invention includes an electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier using the toner of the present invention to form a toner image, transfer means for transferring the toner image formed on the electrostatic latent image carrier to the surface of a recording medium, and fixing means for fixing the toner image transferred to the surface of the recording medium, and may further include other means such as a static eliminating means, a cleaning means, a recycling means, and a control means, as necessary.

[0037] The image forming method of the present invention includes an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier, a developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier using the toner of the present invention to form a toner image, a transfer step of transferring the toner image formed on the electrostatic latent image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium, and may further include other steps such as a static eliminating step, a cleaning step, a recycling step, and a control step, as necessary.

[0038] -Electrostatic latent image forming process and electrostatic latent image forming means- The electrostatic latent image forming step is a step of forming an electrostatic latent image on an electrostatic latent image bearing member. The electrostatic latent image forming means is a means for forming an electrostatic latent image on an electrostatic latent image carrier. The electrostatic latent image forming step can be suitably carried out by the electrostatic latent image forming means.

[0039] The latent image carrier (hereinafter, sometimes referred to as "electrophotographic photoreceptor" or "photoreceptor") is not particularly limited in terms of material, shape, structure, size, etc., and can be appropriately selected from known ones. A preferred shape is a drum, and examples of the material include inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors such as polysilane and phthalopolymethine. Examples of the organic photoreceptor include a laminated photoreceptor having a laminated structure in which a layer (charge generation layer) in which a charge generation material such as metal-free phthalocyanine or titanyl phthalocyanine is dispersed in a binder resin and a layer (charge transport layer) in which a charge transport material is dispersed in a binder resin are stacked on a support such as an aluminum drum, and a single-layer photoreceptor having a single-layer photosensitive layer in which both a charge generation material and a charge transport material are dispersed in a binder resin on a support. In the single-layer type photoreceptor, a hole transport material and an electron transport material can be added to the photosensitive layer as charge transport materials. An undercoat layer may be provided between the support and the multilayer charge generating layer or the single-layer photosensitive layer.

[0040] The electrostatic latent image can be formed, for example, by uniformly charging the surface of the electrostatic latent image bearing member and then exposing it to light in an imagewise manner.

[0041] The electrostatic latent image forming means preferably has at least a charging means (charger) for uniformly charging the surface of the electrostatic latent image carrier, and an exposure means (exposure device) for imagewise exposing the surface of the electrostatic latent image carrier.

[0042] The charging can be carried out, for example, by applying a voltage to the surface of the electrostatic latent image bearing member using the charger. The charger is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a known contact charger equipped with a conductive or semiconductive roll, brush, film, rubber blade, etc., and a non-contact charger utilizing corona discharge such as a corotron or scorotron. The charger is preferably one that is arranged in contact or non-contact with the electrostatic latent image carrier and charges the surface of the electrostatic latent image carrier by applying a superimposed DC and AC voltage to it, or one that is a charging roller that is arranged in close proximity to the electrostatic latent image carrier but not in contact with it via a gap tape and charges the surface of the electrostatic latent image carrier by applying a superimposed DC and AC voltage to the charging roller.

[0043] The exposure can be carried out, for example, by exposing the surface of the electrostatic latent image bearing member to light in an imagewise manner using the exposure unit. The exposure device is not particularly limited as long as it can expose the surface of the electrostatic latent image bearing member charged by the charger in the form of an image to be formed, and can be appropriately selected depending on the purpose. Examples of the exposure device include various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system. In the present invention, a backlight system may be employed in which exposure is performed imagewise from the back side of the electrostatic latent image bearing member.

[0044] -Developing process and developing means- The developing step is a step of developing the electrostatic latent image formed on the electrostatic latent image carrier with the toner to form a toner image. The developing unit is a unit that develops the electrostatic latent image formed on the electrostatic latent image carrier with the toner to form a toner image. The developing step can be suitably carried out by the developing means.

[0045] The toner image can be formed, for example, by developing the electrostatic latent image with the toner. The developing means preferably includes at least a developing device that contains the toner and can apply the toner to the electrostatic latent image in a contact or non-contact manner, and more preferably includes a developing device that includes a toner container. The developing device may be a single-color developing device or a multi-color developing device, and a suitable example is one having an agitator that charges the toner by frictional agitation and a rotatable magnetic roller.

[0046] -Transfer process and transfer means- The transfer step is a step of transferring the toner image formed on the electrostatic latent image carrier onto the surface of a recording medium. The transfer means is a means for transferring the toner image formed on the electrostatic latent image carrier onto the surface of a recording medium. The transfer step can be suitably carried out by the transfer means.

[0047] The transfer step is preferably carried out using an intermediate transfer body, where a toner image is primarily transferred onto the intermediate transfer body, and then the toner image is secondarily transferred onto the recording medium. A more preferred embodiment includes a first transfer step in which two or more colors, preferably full-color toner, are used as the toner, and the toner image is transferred onto the intermediate transfer body to form a composite transfer image, and a second transfer step in which the composite transfer image is transferred onto the recording medium.

[0048] The transfer means (primary transfer means and secondary transfer means) preferably includes at least a transfer device that peels and charges the toner image formed on the electrostatic latent image carrier (photosensitive member) onto the recording medium. The number of transfer devices may be one or more. Examples of the transfer device include a corona transfer device that uses corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.

[0049] The recording medium is not particularly limited and can be appropriately selected from known recording media (recording paper).

[0050] - Fixing process and fixing means - The fixing step is a step of fixing the toner image transferred onto the surface of the recording medium. The fixing unit is a unit for fixing the toner image transferred onto the surface of the recording medium. The fixing step can be suitably carried out by the fixing means.

[0051] The fixing step may be carried out each time the developer of each color is transferred to the recording medium, or may be carried out simultaneously with the developers of each color stacked together. The fixing device as the fixing means is not particularly limited and can be appropriately selected depending on the purpose, but known heating and pressurizing means are suitable, such as a combination of a heating roller and a pressure roller, or a combination of a heating roller, a pressure roller and an endless belt.

[0052] -Static removal process and static removal means- The charge removal step is a step of removing electricity by applying a charge removal bias to the electrostatic latent image bearing member. The charge removing unit is a unit that applies a charge removing bias to the electrostatic latent image bearing member to remove electricity. The charge removal step can be suitably carried out by the charge removal means.

[0053] The discharging means is not particularly limited as long as it can apply a discharging bias to the electrostatic latent image bearing member, and can be appropriately selected from known discharging devices, such as a discharging lamp.

[0054] -Cleaning process and cleaning means- The cleaning step is a step of removing the toner remaining on the electrostatic latent image bearing member. The cleaning means is a means for removing the toner remaining on the electrostatic latent image carrier. The cleaning step can be suitably carried out by the cleaning means. The cleaning means is not particularly limited as long as it can remove the toner remaining on the electrostatic latent image carrier, and can be appropriately selected from known cleaners, such as a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, a brush cleaner, and a web cleaner.

[0055] -Recycling process and means- The recycling step is a step of recycling the toner removed in the cleaning step to the developing means. The recycling unit is a unit for recycling the toner removed by the cleaning unit to the developing unit. There are no particular limitations on the recycling unit, and examples of the recycling unit include known transport units. The recycling step can be suitably carried out by the recycling means.

[0056] -Control process and control means- The control step is a step of controlling each of the steps. The control means is a means for controlling each of the means. The control step can be suitably carried out by the control means. The control means is not particularly limited as long as it can control the movement of each of the means, and can be appropriately selected depending on the purpose. Examples of the control means include devices such as a sequencer and a computer.

[0057] (Manufacturing method of printed matter) The method for producing a printed matter of the present invention forms a printed matter on a recording medium using an image forming apparatus including: an electrostatic latent image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the electrostatic latent image carrier; a developing unit that develops the electrostatic latent image formed on the electrostatic latent image carrier with the toner to form a toner image; a transfer unit that transfers the toner image formed on the electrostatic latent image carrier to the surface of a recording medium; and a fixing unit that fixes the toner image transferred to the surface of the recording medium. The method may include other steps as necessary. The printed matter has an image formed on the recording medium using the toner of the present invention. Each step in the method for producing a printed matter can be the same as that in the image forming method, and therefore a duplicated description will be omitted.

[0058] An example of an electrophotographic developing apparatus according to the present invention is shown in FIG. In FIG. 3, reference numeral 101A denotes a drive roller, 101B denotes a driven roller, 102 denotes a photosensitive belt, 103 denotes a charger, 104 denotes a laser writing unit, 105A to 105D denote developing units containing toner of each color, yellow, magenta, cyan, and black, respectively, 106 denotes a paper feed cassette, 107 denotes an intermediate transfer belt, 107A denotes a drive shaft roller for driving the intermediate transfer belt, 107B denotes a driven shaft roller for supporting the intermediate transfer belt, 108 denotes a cleaning device, 109 denotes a fixing roller, 109A denotes a pressure roller, 110 denotes a paper discharge tray, and 113 denotes a paper transfer roller.

[0059] In this color image forming apparatus, a flexible intermediate transfer belt 107 is used for the transfer drum. The intermediate transfer belt 107, which is an intermediate transfer body, is stretched around a drive shaft roller 107A and a pair of driven shaft rollers 107B and is circulated and transported clockwise, with the belt surface between the pair of driven shaft rollers 107B being in horizontal contact with the photosensitive belt 102 on the outer periphery of the drive roller 101A. During normal color image output, the toner images of each color formed on the photosensitive belt 102 are transferred to the intermediate transfer belt 107 as they are formed, to combine color toner images, which are then transferred all at once by the paper transfer roller 113 onto the transfer paper transported from the paper feed cassette 106. After transfer, the transfer paper is transported between the fixing roller 109 and pressure roller 109A of the fixing device, and after being fixed by the fixing roller 109 and pressure roller 109A, it is discharged to the paper discharge tray 110. When the developing units 105A to 105E develop toner, the toner concentration of the developer contained in the developing unit decreases. The decrease in toner concentration of the developer is detected by a toner concentration sensor (not shown). When the decrease in toner concentration is detected, a toner supply device (not shown) connected to each developing unit operates to supply toner and increase the toner concentration. At this time, the toner supplied may be a developer for a so-called trickle development method in which carrier and toner are mixed, as long as the developing unit is equipped with a developer discharge mechanism.

[0060] In FIG. 2, an image is formed by superimposing toner images on an intermediate transfer belt, but the electrophotographic image forming apparatus of the present invention can also be a system in which transfer is performed directly from a transfer drum to a recording medium without using an intermediate transfer belt.

[0061] FIG. 4 is a diagram showing an example of a developing device used in the present invention, and modified examples such as those described below also fall within the scope of the present invention. In FIG. 4, the developing device 40, which is disposed opposite the photosensitive member 20 serving as a latent image carrier, is mainly composed of a developing sleeve 41 serving as a developer carrier, a developer accommodating member 42, a doctor blade 43 serving as a regulating member, a support case 44, etc. A toner hopper (45) is attached to a support case 44 having an opening on the photoreceptor 20 side, and serves as a toner storage section for storing toner 21 inside. A developer storage section 46, adjacent to the toner hopper 45, for storing a developer made up of toner 21 and carrier 23, is provided with a developer stirring mechanism 47 for stirring the toner 21 and carrier 23 and imparting friction / peel-off charge to the toner 21. A toner agitator 48 as a toner supply means rotated by a driving means (not shown) and a toner supply mechanism 49 are disposed inside the toner hopper 45. The toner agitator 48 and the toner supply mechanism 49 agitate and send the toner 21 in the toner hopper 45 toward the developer container 46.

[0062] A developing sleeve 41 is disposed in the space between the photoreceptor 20 and the toner hopper 45. The developing sleeve 41 is rotated in the direction of the arrow in the figure by a driving means (not shown). In order to form a magnetic brush with the carrier 23, the developing sleeve 41 has a magnet (not shown) disposed therein in a fixed position relative to the developing device 40 as a magnetic field generating means. A doctor blade 43 is integrally attached to the developer accommodating member 42 on the side opposite to the side attached to the support case 44. In this example, the doctor blade 43 is disposed with a certain gap maintained between its tip and the outer circumferential surface of the developing sleeve 41.

[0063] Using such an apparatus, but not limited to it, the image forming method of the present invention is carried out as follows. That is, with the above-described configuration, the toner 21 sent out from inside the toner hopper 45 by the toner agitator 48 and the toner supply mechanism 49 is transported to the developer storage section 46, where it is agitated by the developer agitation mechanism 47, thereby giving it the desired friction / peel-off charge, and is then carried as a developer together with the carrier 23 by the developing sleeve 41 and transported to a position facing the outer peripheral surface of the photosensitive member 20, where only the toner 21 electrostatically bonds with the electrostatic latent image formed on the photosensitive member 20, thereby forming a toner image on the photosensitive member 20.

[0064] FIG. 5 shows an example of an image forming apparatus having the developing device shown in FIG. Around the drum-shaped photoconductor 20, a charging member 32, an image exposure system 33, a developing device 40, a transfer device 50, a cleaning device 60, and a discharging lamp 70 are arranged. In this example, the surface of the charging member 32 is in a non-contact state with the surface of the photoconductor 20, with a gap of approximately 0.2 mm between them. When the photoconductor 20 is charged by the charging member 32, a voltage application means (not shown) applies an electric field to the charging member 32, in which an AC component is superimposed on a DC component, thereby effectively reducing charging unevenness. The image forming method, including the developing method, is carried out as follows:

[0065] The image formation process can be explained as a negative-positive process. Photoconductor 20, typically a photoconductor (OPC) with an organic photoconductive layer, is discharged by discharge lamp 70, then uniformly charged negatively by charging member 32, such as a charger or charging roller, and a latent image is formed by laser light irradiated from image exposure system 33, such as a laser optical system (in this example, the absolute value of the potential of the exposed portion is lower than the absolute value of the potential of the unexposed portion). Laser light is emitted from a semiconductor laser and scanned across the surface of photoreceptor 20 in the direction of the rotation axis of photoreceptor 20 by a polygonal mirror (polygon) or the like rotating at high speed. The latent image formed in this way is developed with a developer consisting of a mixture of toner and carrier supplied onto developing sleeve 41, which is a developer carrier in developing device 40, to form a toner image. When developing the latent image, a voltage application mechanism (not shown) applies a DC voltage of an appropriate magnitude or a development bias formed by superimposing an AC voltage on this to developing sleeve 41 between the exposed and non-exposed areas of photoreceptor 20.

[0066] Meanwhile, a transfer medium (e.g., paper) 80 is fed from a paper feed mechanism (not shown) and is fed between the photosensitive member 20 and the transfer device 50 in synchronization with the leading edge of the image by a pair of upper and lower registration rollers (not shown), and the toner image is transferred. At this time, it is preferable that a potential of a polarity opposite to the polarity of the toner charge is applied to the transfer device 50 as a transfer bias. Thereafter, the transfer medium 80 is separated from the photosensitive member 20, and a transferred image is obtained. Furthermore, the toner remaining on the photoreceptor 20 is collected into a toner collection chamber 62 in the cleaning device 60 by a cleaning blade 61 serving as a cleaning member. The collected toner may be transported to the developer container 46 and / or the toner hopper 45 by a toner recycling means (not shown) and reused. The image forming apparatus may be an apparatus in which a plurality of the above-mentioned developing devices are arranged, and toner images are sequentially transferred onto a transfer medium, and then sent to a fixing mechanism where the toner is fixed by heat or the like, or an apparatus in which a plurality of toner images are first transferred onto an intermediate transfer medium, and then these are transferred to the transfer medium all at once and then fixed in the same manner.

[0067] Figure 6 shows another example of an image forming apparatus used in the present invention. Photoreceptor 20 has at least a photosensitive layer provided on a conductive support, and is driven by drive rollers 24a and 24b. The following steps are repeatedly performed: charging by charging member 32, image exposure by image exposure system 33, development by developing device 40, transfer using transfer device 50, pre-cleaning exposure by pre-cleaning exposure light source 26, cleaning by brush-like cleaning means 64 and cleaning blade 61, and discharging by discharging lamp 70. In Figure 6, pre-cleaning exposure is performed on photoreceptor 20 (of course, in this case the support is translucent) from the support side.

[0068] The image forming apparatus of the present invention has at least an electrostatic latent image carrier, an electrostatic latent image forming means, and a developing means, and may further have other means as required. The image forming method according to the present invention includes at least an electrostatic latent image forming step and a development step, and may further include other steps as required. The image forming method can be suitably performed by the image forming apparatus, the electrostatic latent image forming step can be suitably performed by the electrostatic latent image forming means, the developing step can be suitably performed by the developing means, and the other steps can be suitably performed by the other means.

[0069] More preferably, the image forming apparatus of the present invention includes an electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, developing means having toner for developing the electrostatic latent image formed on the electrostatic latent image carrier with toner to form a toner image, transfer means for transferring the toner image formed on the electrostatic latent image carrier to the surface of a recording medium, and fixing means for fixing the toner image transferred to the surface of the recording medium.

[0070] Furthermore, the image forming method of the present invention more preferably includes an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier, a developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier with toner to form a toner image, a transfer step of transferring the toner image formed on the electrostatic latent image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0071] Next, one embodiment of the image forming apparatus of the present invention will be described with reference to Fig. 7. The color image forming apparatus 100A shown in Fig. 7 includes a photosensitive drum 10 (hereinafter sometimes referred to as "photosensitive member 10") as the electrostatic latent image carrier, a charging roller 20 as the charging means, an exposure device 30 as the exposure means, a developing device 40 as the developing means, an intermediate transfer body 50, a cleaning device 60 as the cleaning means having a cleaning blade, and a discharging lamp 70 as the discharging means. The intermediate transfer body 50 is an endless belt that is designed to move in the direction of the arrow by three rollers 51 arranged inside and tensioning it. Some of the three rollers 51 also function as transfer bias rollers that can apply a predetermined transfer bias (primary transfer bias) to the intermediate transfer body 50. A cleaning device 90 having a cleaning blade is arranged near the intermediate transfer body 50. Also, a transfer roller 80 serving as the transfer means that can apply a transfer bias for transferring (secondary transfer) the developed image (toner image) to transfer paper 95 as a recording medium is arranged near the intermediate transfer body 50, facing the intermediate transfer body 50. A corona charger 58 for applying an electric charge to the toner image on the intermediate transfer body 50 is arranged around the intermediate transfer body 50, between the contact point between the photoreceptor 10 and the intermediate transfer body 50 and the contact point between the intermediate transfer body 50 and the transfer paper 95, in the direction of rotation of the intermediate transfer body 50.

[0072] In this embodiment, an elastic intermediate transfer belt can also be used as the intermediate transfer body 50. As the elastic intermediate transfer belt, for example, one in which a flexible elastic layer is laminated on a rigid base layer that is relatively flexible can be used. In order to prevent the intermediate transfer body 50 from meandering, a guide member for preventing deviation may be provided on the inner peripheral surface of the intermediate transfer body 50 . It is also possible to provide a collecting means for receiving the toner etc. removed by the intermediate transfer member cleaning device 90. A dish-shaped tray or the like can be used as the collecting means.

[0073] The developing device 40 is composed of a developing belt 41 as the developer carrier, and a black (Bk) developing unit 45K, a yellow (Y) developing unit 45Y, a magenta (M) developing unit 45M, and a cyan (C) developing unit 45C arranged around the developing belt 41. The black developing unit 45K includes a developer container 42K, a developer supply roller 43K, and a developing roller 44K. The yellow developing unit 45Y includes a developer container 42Y, a developer supply roller 43Y, and a developing roller 44Y. The magenta developing unit 45M includes a developer container 42M, a developer supply roller 43M, and a developing roller 44M. The cyan developing unit 45C includes a developer container 42C, a developer supply roller 43C, and a developing roller 44C. The developing belt 41 is an endless belt, rotatably stretched around a plurality of belt rollers, and is partially in contact with the electrostatic latent image carrier 10 .

[0074] Specific embodiments of the image forming method will be described below. Image data sent to an image processing unit (hereinafter referred to as "IPU") creates image signals for each of the four colors: Y (yellow), M (magenta), C (cyan), and K (black). Next, the image processing unit transmits the Y, M, C, and K image signals to the writing unit. The writing unit modulates and scans four laser beams for Y, M, C, and K, respectively, and creates electrostatic latent images on each photosensitive drum in sequence after the photosensitive drums are charged by the charging unit. In this example, for example, the first photosensitive drum corresponds to K, the second photosensitive drum to Y, the third photosensitive drum to M, and the fourth photosensitive drum to C. Next, a toner image of each color is formed on the photosensitive drum by a developing unit as a developing and adhering means. A transfer sheet fed by a paper feeder is transported on a transfer belt, and the toner image on the photosensitive drum is transferred sequentially onto the transfer sheet by a transfer charger. After the transfer process is completed, the transfer paper is transported to a fixing unit, where the transferred toner image is fixed onto the transfer paper. After the transfer process is completed, the toner remaining on the photosensitive drum is removed by a cleaning unit. [Example]

[0075] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples and comparative examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0076] Example 1 The present invention will be described in more detail below with reference to examples. It should be noted that those skilled in the art can easily make appropriate changes and modifications to the examples of the present invention shown below to create other embodiments, and these changes and modifications are included in the present invention. The following description is an example of a preferred embodiment of the present invention and does not limit the present invention. Unless otherwise specified, parts refer to parts by weight.

[0077] <Measurement of the glass transition temperature (Tg) of the binder resin> The glass transition point (Tg) in the present invention was determined by using a differential scanning calorimeter (DSC210, manufactured by Seiko Instruments Inc.) to measure 0.01 g to 0.02 g of a sample into an aluminum pan, heating the sample to 200°C, and then cooling the sample from that temperature at a rate of 10°C / min to 20°C. The sample was then heated again at a rate of 10°C / min, and the glass transition point was determined as the temperature at the intersection of an extension of the baseline below the highest endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the peak apex.

[0078] <Measurement of Acid Value of Toner and Binder Resin> The acid values ​​of the toner and binder resin were measured in accordance with JIS K0070-1992 by the method described above. In the following examples and comparative examples, one type of binder resin was used, so the acid value of the binder resin and the acid value of the toner were almost the same.

[0079] <Hydroxyl value of toner and binder resin> The hydroxyl values ​​of the toner and binder resin were measured in accordance with JIS K0070-1992 by the method described above.

[0080] <Measurement of molecular weight of binder resin> The number average molecular weight and weight average molecular weight of the binder resin were determined by measuring the molecular weight distribution of the THF-soluble portion using a GPC (gel permeation chromatography) measuring device GPC-150C (manufactured by Waters Corporation). Measurements were performed using a column (KF801-807, manufactured by Showdex) using the following method. The column was stabilized in a heat chamber at 40°C, and THF solvent was passed through the column at this temperature at a flow rate of 1 ml / min. 0.05 g of sample was thoroughly dissolved in 5 g of THF and then filtered through a pretreatment filter (0.45 μm pore size, Chromatodisk (manufactured by Kurabo Industries, Ltd.)). Finally, 50-200 μl of the resin THF sample solution, adjusted to a sample concentration of 0.05-0.6 wt%, was injected and measured. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the THF-soluble portion of the sample were measured by calculating the molecular weight distribution of the sample from the relationship between the logarithm of the calibration curve and the count number, prepared using several monodisperse polystyrene standard samples.

[0081] The standard polystyrene sample used to create the calibration curve was a polystyrene sample manufactured by Pressure Chemical Co. with a molecular weight of 6 x 10 2 , 2.1×10 2 , 4×10 2 , 1.75×10 4 , 5.1×10 4 , 1.1×10 5 , 3.9 × 10 5 , 8.6×10 5 , 2 × 106 , 4.48×10 6 (or a product manufactured by Toyo Soda Kogyo Co., Ltd.) and at least 10 standard polystyrene samples are suitable, so these samples were used. An RI (refractive index) detector was used as the detector.

[0082] <Measuring the melting point of wax> Using a differential scanning calorimeter (Seiko Instruments Inc., DSC210), 0.01 to 0.02 g of sample was weighed into an aluminum pan and heated to 150°C at a rate of 10°C / min, and the temperature of the highest endothermic peak was taken as the melting point.

[0083] [Production of Polyester Resins 1 to 4] [Production of polyester resin 1] A 4000g mixture of 40 mol% polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane (hereafter abbreviated as "BPA-PO"), 60 mol% ethylene glycol, 40 mol% adipic acid, 20 mol% terephthalic acid, 20 mol% isophthalic acid, and 20 mol% trimellitic acid was added to a 5-L autoclave equipped with a distillation column. The esterification reaction was carried out at atmospheric pressure at 170-260°C without a catalyst. Subsequently, 400 ppm of antimony trioxide (based on the total carboxylic acid components) was added to the reaction system, and polycondensation was carried out at 250°C under a vacuum of 3 Torr while removing glycol from the system, yielding [Polyester Resin 1]. The crosslinking reaction was continued until the stirring torque reached 10 kg cm (100 ppm). The reaction was then terminated by releasing the vacuum. The physical properties of the obtained [Polyester Resin 1] are shown in Table 1.

[0084] [Production of polyester resin 2] A total of 4000 g of the aromatic diol components (BPA-PO, 40 mol % ethylene glycol, 40 mol % adipic acid, 20 mol terephthalic acid, 20 mol % isophthalic acid, and 20 mol % trimellitic acid) was mixed in a 5-L autoclave equipped with a distillation column. The esterification reaction was carried out under atmospheric pressure at 170-260°C without a catalyst. After adding 400 ppm of antimony trioxide (based on the total carboxylic acid components) to the reaction system, polycondensation was carried out at 250°C under a vacuum of 3 Torr while removing glycol from the system, yielding [Polyester Resin 2]. The crosslinking reaction was continued until the stirring torque reached 10 kg·cm (100 ppm), at which point the reaction was terminated by releasing the vacuum. The properties of the resulting [Polyester Resin 2] are listed in Table 1.

[0085] [Production of polyester resin 3] A total of 4000 g of the aromatic diol components (BPA-PO, ethylene glycol, adipic acid, terephthalic acid, isophthalic acid, and trimellitic acid) was mixed in a 5-liter autoclave equipped with a distillation column. The monomers were mixed in a ratio of 60 mol% by mass of BPA-PO, 40 mol% by mass of ethylene glycol, 40 mol% by mass of adipic acid, 10 mol% by mass of terephthalic acid, 10 mol% by mass of isophthalic acid, and 40 mol% by mass of trimellitic acid. The esterification reaction was carried out at atmospheric pressure and 170-260°C without a catalyst. After this, 400 ppm of antimony trioxide (based on the total carboxylic acid components) was added to the reaction system, and polycondensation was carried out at 250°C under a vacuum of 3 Torr while removing glycol from the system, yielding [Polyester Resin 3]. The crosslinking reaction was continued until the stirring torque reached 10 kg·cm (100 ppm). The reaction was terminated by releasing the vacuum. The properties of the resulting [Polyester Resin 3] are listed in Table 1.

[0086] [Production of polyester resin 4] The monomers were mixed in the following mass ratios: 40 mol% BPA-PO (as the aromatic diol component), 20 mol% ethylene glycol, 40 mol% glycerin, 40 mol% adipic acid, 20 mol% terephthalic acid, 20 mol% isophthalic acid, and 20 mol% trimellitic acid. A total of 4000 g of these monomers was charged into a 5-L autoclave equipped with a distillation column. Esterification was carried out at atmospheric pressure and 170-260°C without a catalyst. After this, 400 ppm of antimony trioxide (based on the total carboxylic acid components) was added to the reaction system, and polycondensation was carried out at 250°C under a vacuum of 3 Torr while removing glycol from the system, yielding [Polyester Resin 4]. The crosslinking reaction was continued until the stirring torque reached 10 kg·cm (100 ppm). The reaction was terminated by releasing the vacuum on the reaction system. The physical properties of the resulting [Polyester Resin 4] are listed in Table 1.

[0087] [Table 1]

[0088] [Binder resin manufacturing example: Manufacturing of polyol resin 1] To prepare the polyol resin, 1000 g of low-molecular-weight bisphenol A epoxy resin (number-average molecular weight: approximately 1000), 50 g of terephthalic acid, 5 g of benzoic acid, and 300 g of xylene were added to a separable flask equipped with a stirrer, thermometer, nitrogen inlet, and condenser. The mixture was heated to 70-100°C under a nitrogen atmosphere, and 0.183 g of lithium chloride was added. The temperature was then raised to 160°C, and the xylene was distilled off under reduced pressure. The mixture was then polymerized at a reaction temperature of 180°C for 4-6 hours to obtain [Polyol Resin 1]. The glass transition temperature was 61.4°C, the acid value was 11.5 mg KOH / g, the molecular weight was 9,500 Mw, the molecular weight was 2,750 Mn, and the Mw / Mn ratio was 3.5.

[0089] [Toner manufacturing method] [Production of Toners 1 to 12] The toner raw materials were premixed using a Henschel mixer (FM20B, manufactured by Nippon Coke and Engineering Co., Ltd.) according to the formula shown in Table 2, and then melted and kneaded at a temperature of 100 to 130°C in a single-screw kneader (Ko-Kneader kneader, manufactured by Buss). The resulting kneaded mixture was cooled to room temperature and coarsely pulverized to 200 to 300 μm using a Rotoplex. Next, using a counter jet mill (100AFG, manufactured by Hosokawa Micron Corporation), the air pressure was appropriately adjusted to obtain a weight-average particle size of 6.5±0.3 μm. The mixture was then finely pulverized using an air classifier (EJ-LABO, manufactured by Matsubo Corporation) while appropriately adjusting the louver opening to obtain a weight-average particle size of 7±0.2 μm and a weight-average particle size / number-average particle size ratio of 1.25 or less, yielding toner base particles 1 to 12. Next, 1.0 part of additives (HDK-2000, manufactured by Clariant Co., Ltd.) and 1.0 part of additives (H05TD, manufactured by Clariant Co., Ltd.) were mixed with 100 parts of the toner base particles using a Henschel mixer to produce [Toner 1] to [Toner 12].

[0090] [Manufacturing of two-component developers] <Creating the carrier> Silicone resin (organo straight silicone) 100 parts Toluene 100 parts γ-(2-aminoethyl)aminopropyltrimethoxysilane 5 parts Carbon black: 10 parts The mixture was dispersed in a homomixer for 20 minutes to prepare a coating layer forming solution. This coating layer forming solution was applied to Mn ferrite particles with a weight average particle size of 35 μm as the material, and then dried using a fluidized bed coating device, with the temperature in the fluidized bed controlled at 70°C, so that the average film thickness on the surface of the core material became 0.20 μm. The obtained carrier was fired in an electric furnace at 180°C for 2 hours to obtain a carrier.

[0091] <Preparation of two-component developers 1 to 12> The prepared [Toner 1] to [Toner 12] and carrier were mixed uniformly and charged for 5 minutes using a Turbler mixer (manufactured by Willy & Bachofen (WAB)) at 48 rpm to prepare two-component developers 1 to 12. The toner and carrier mixing ratio was adjusted to match the toner concentration of the initial developer for the evaluation machine: 4% by mass.

[0092] [Evaluation of toner characteristics] <Volume average particle diameter of toner> The volume average particle diameter of the toner was measured using a Coulter Counter Multisizer III. The toner to be measured was added to an electrolyte solution containing a surfactant, and dispersed for 1 minute using an ultrasonic disperser. 50,000 particles were measured to calculate the volume average particle diameter of the toner. The results are shown in Table 3.

[0093] <Average circularity> Using a flow particle image analyzer (FPIA-3000, manufactured by Sysmex Corporation), 0.1 to 0.5 ml of alkylbenzene sulfonate salt was added as a dispersant to 100 ml to 150 ml of water in a container from which impurities had been removed in advance, and then approximately 0.1 g to 0.5 g of the measurement sample was added. The suspension with the dispersed sample was subjected to a dispersion treatment in an ultrasonic disperser for approximately 1 to 3 minutes, and the dispersion concentration was set to 3,000 particles / μl to 10,000 particles / μl, and the shape of the toner was measured using the above-mentioned device. The results are shown in Table 3.

[0094] <State of aromatic petroleum resin at the interface between release agent particle domains and state of aromatic petroleum resin> Using a scanning electron microscope SEM (cold) Hitachi SU8230 (manufactured by Hitachi High-Technologies Corporation), the toner was embedded in epoxy resin, cut out with a microtome, and stained with ruthenium. The cross section was observed and confirmed at 8,000 magnifications. The results of SEM observation of a cross section of the toner of Example 1 are shown in Fig. 1. In the image of Fig. 1, the black parts are the release agent, the gray parts are the aromatic petroleum resin, and the white parts are the binder resin, and it was confirmed that the aromatic petroleum resin was present at the interface between the release agent particle domains and that the aromatic petroleum resin was present in a dispersed state in the polyester resin matrix. FIG. 2 is an image obtained by processing the image of FIG. 1, and more clearly shows the presence of aromatic petroleum resin at the interface between the domains of the release agent particles. The results are shown in Table 2. [Evaluation criteria] ◯: Aromatic petroleum resin is present at the interface between the release agent particle domains, and the aromatic petroleum resin domains are present in a dispersed state in the polyester resin matrix. △: Aromatic petroleum resin is present only at the interface between the release agent particle domains. ×: Aromatic petroleum resin is not present at the interface between the domains of the release agent particles.

[0095] <Low temperature fixability> The obtained toner developer was placed in a modified RICOH IM 6000 copying machine (manufactured by Ricoh Co., Ltd.) (linear speed: 256 mm / sec), and an image was output. 2 The solid image was output onto a recording medium (Ricoh Co., Ltd., Type 6200) through exposure, development, and transfer processes. The fixing temperature was output in 5°C increments, and the lowest temperature at which cold offset did not occur (lower limit fixing temperature: low-temperature fixing ability) was measured. The low-temperature fixing ability was evaluated based on the following evaluation criteria, and the results are shown in Table 3. A rating of "△" or better was deemed sufficient for practical use. [Evaluation criteria] ◎: Less than 120℃ 〇: 120℃ or higher but less than 125℃ △: 125℃ or higher but lower than 130℃ ×: 130℃ or higher

[0096] <Hot offset resistance> Each developer was placed in a storage unit of a modified copy machine RICOH IM 6000 (linear speed: 256 mm / sec) manufactured by Ricoh Co., Ltd., and the amount of developer adhered was 0.4 mg / cm 2 A solid image was formed on a recording medium (Type 6200, manufactured by Ricoh Co., Ltd.) so that the image satisfies the following criteria. The fixing temperature was sequentially changed in 5°C increments, and the upper limit temperature at which hot offset did not occur (upper limit fixing temperature: hot offset property) was measured. The hot offset property was evaluated based on the following criteria, and the results are shown in Table 3. A rating of "△" or better was considered to be sufficient for practical use. [Evaluation criteria] ◎: Upper limit fixing temperature is 200℃ or more 〇: Upper limit fixing temperature is 190℃ or more and less than 200℃ △: Upper limit fixing temperature is 180℃ or more and less than 190℃ ×: Upper limit fixing temperature is less than 180°C

[0097] <Heat-resistant storage stability> The shelf life was measured using a needle penetration tester (manufactured by Nikka Engineering Co., Ltd.). Specifically, 10 g of each toner was weighed out and placed in a 30 ml glass container (screw vial) in an environment of 20 to 25°C and 40 to 60% RH, and the lid was then closed. The glass container containing the toner was tapped 100 times, and then left in a thermostatic chamber set at 50°C for 24 hours. After that, the penetration was measured with a penetration tester, and the heat-resistant storage stability was evaluated according to the following evaluation criteria. The larger the penetration value, the better the heat resistance storage property. The results are shown in Table 3, and a grade of "Fair" or better was judged to be sufficient for practical use. [Evaluation criteria] ◎: Penetration is 30mm or more ○: Penetration is 25mm or more and less than 30mm △: Penetration is 20mm or more and less than 25mm ×: Penetration less than 20 mm

[0098] <Filming> Each developer was placed in a modified Ricoh IM 6000 copier (linear speed: 256 mm / sec), and a continuous running test was carried out using TANOSEE PPC Paper Type FW (A4) from Otsuka Shokai Co., Ltd., with a print rate of 1% image coverage. Filming on the photoreceptor and the presence or absence of abnormal images (uneven half-tone density) associated with filming were evaluated after 20,000, 50,000, and 100,000 sheets. The occurrence of filming was more detrimental the more sheets were run. The results are shown in Table 3, and a grade of "Fair" or better was judged to be sufficient for practical use. [Evaluation criteria] ○: Not generated even with 100,000 copies △: Occurs at 50,000 copies ×: Occurs at 10,000 sheets

[0099] <Developer characteristic evaluation> Each developer was placed in a modified RICOH IM 6000 copying machine (linear speed: 256 mm / sec) manufactured by Ricoh Co., Ltd., and a continuous running test was carried out using a Ricoh Co., Ltd. Type 6200 at an image area ratio of 5%, and the charge amount of the carrier was measured initially and after running 100,000 sheets, and the amount of decrease in charge amount was calculated. The initial carrier charge amount (Q1) was measured using a sample prepared by mixing each toner and carrier at a mass ratio of 96:4 and triboelectrically charging the mixture using a blow-off device TB-200 (manufactured by Toshiba Chemical Co., Ltd.) The carrier charge amount (Q2) after running was measured in the same manner as above, except that the carrier used was one from which the toner in the developer after running had been removed using a blow-off device. The results are shown in Table 3, and a grade of "Fair" or better was judged to be sufficient for practical use. [Evaluation criteria] ◎: Q1-Q2≦5 ○:5 <Q1-Q2≦10 △:10 <Q1-Q2≦20 ×:20 <Q1-Q2

[0100] [Table 2]

[0101] [Table 3]

[0102] The present invention can be embodied, for example, as follows. (1) A toner comprising toner particles containing a polyester resin, a release agent, and an aromatic petroleum resin, the toner has an acid value of 6 mgKOH / g or more and 12 mgKOH / g or less; When a cross section of the toner particle is observed with a scanning electron microscope, the aromatic petroleum resin is present at the interface between domains of the release agent, and the domains of the aromatic petroleum resin are present in a dispersed state in a matrix of the polyester resin. A toner characterized by: (2) The toner according to (1) above, wherein the toner has a hydroxyl value of 25 mgKOH / g or more and 45 mgKOH / g or less. (3) The toner according to (1) or (2) above, wherein the release agent is a hydrocarbon wax. (4) The toner according to any one of (1) to (3) above, wherein the amount of the aromatic petroleum resin added is 5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the toner. (5) The toner according to any one of (1) to (4) above, having an average circularity of 0.93 or more and 0.96 or less. (6) A developer comprising the toner according to any one of (1) to (5) above and a carrier. (7) A toner storage unit that stores the toner according to any one of (1) to (5) above. (8) an electrostatic latent image carrier; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier; a developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier with toner to form a toner image; a transfer means for transferring the toner image onto a transfer body, The toner is the toner according to any one of (1) to (5) above. An image forming apparatus characterized by: (9) a charging step of charging an electrostatic latent image carrier; forming an electrostatic image on the charged electrostatic latent image carrier; a developing step of developing the electrostatic image with toner to form a toner image; a transfer step of transferring the toner image onto a transfer body; a cleaning step of cleaning the surface of the electrostatic latent image carrier after transfer with a cleaning member; a fixing step of fixing the toner image. The toner is the toner according to any one of (1) to (5) above. An image forming method comprising: (10) The image forming method according to (9) above, further comprising a recycling system in which the toner recovered from the surface of the electrostatic latent image carrier in the cleaning step is used as developing toner in the developing step. [Explanation of symbols]

[0103] (About Figure 3) 101A Drive roller 101B driven roller 102 Photoconductor belt 103 Charger 104 Laser writing unit 105A to 105D: Developing units containing yellow, magenta, cyan, and black toner, respectively 106 Paper cassette 107 Intermediate transfer belt 107A Drive shaft roller for driving intermediate transfer belt 107B Driven shaft roller supporting intermediate transfer belt 108 Cleaning device 109 Fuser roller 109A Pressure roller 110 Paper output tray 113 Paper transfer roller

[0104] (About Figure 4) 20 Photoreceptor 21 Toner 23 Career 40 Developing device 41 Developing sleeve 42 Developer containing member 43 Developer supply regulating member 44 Support Case 45 Toner hopper 46 Developer storage section 47 Developer stirring mechanism 48 Toner agitator 49 Toner supply mechanism

[0105] (About Figure 5) 20 Photoreceptor 32 Charging member 33 Image exposure system 40 Developing device 41 Developing sleeve 45 Toner hopper 47 Developer stirring mechanism 50 Transcription device 60 Cleaning Device 61 Cleaning blade 62 Toner collection room 70 Static elimination lamp 80 Transfer Media

[0106] (About Figure 6) 20 Photoreceptor 24a Drive roller 24b Drive roller 26 Pre-cleaning exposure light source 32 Charging member 33 Image exposure system 40 Developing device 50 Transcription device 61 Cleaning blade 64 Brush-like cleaning means 70 Static elimination lamp

[0107] (About Figure 7) 10 Electrostatic latent image carrier (photosensitive drum) 20 Charging roller 30 Exposure equipment 40 Developing device 41 Developing belt 42K Developer compartment 42Y Developer storage unit 42M Developer compartment 42C Developer storage unit 42G Developer compartment 43K Developer supply roller 43Y Developer supply roller 43M Developer supply roller 43C Developer supply roller 44K developing roller 44Y developing roller 44M developing roller 44C Developing roller 45K Black Development Unit 45Y Yellow Development Unit 45M Magenta Development Unit 45C Cyan Development Unit 50 Intermediate transfer body 51 Laura 58 Corona charging device 60 Cleaning Device 70 Static elimination lamp 80 Transfer roller 90 Cleaning Device 95 Transfer paper 100A color image forming device [Prior art documents] [Patent documents]

[0108] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-62599 [Patent Document 2] Japanese Patent Publication No. 2021-144186 [Patent Document 3] Japanese Patent Application Publication No. 2023-047237

Claims

1. A toner comprising toner particles containing a polyester resin, a release agent, and an aromatic petroleum resin, the toner has an acid value of 6 mgKOH / g or more and 12 mgKOH / g or less; When a cross section of the toner particle is observed with a scanning electron microscope, the aromatic petroleum resin is present at the interface between domains of the release agent, and the domains of the aromatic petroleum resin are present in a dispersed state in a matrix of the polyester resin. A toner characterized by:

2. 2. The toner according to claim 1, wherein the hydroxyl value of the toner is 25 mgKOH / g or more and 45 mgKOH / g or less.

3. 2. The toner according to claim 1, wherein the release agent is a hydrocarbon wax.

4. 2. The toner according to claim 1, wherein the amount of the aromatic petroleum resin added is 5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the toner.

5. 2. The toner according to claim 1, wherein the average circularity is 0.93 or more and 0.96 or less.

6. A developer comprising the toner according to claim 1 and a carrier.

7. A toner storage unit containing the toner according to any one of claims 1 to 5.

8. an electrostatic latent image carrier; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier; a developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier with toner to form a toner image; a transfer means for transferring the toner image onto a transfer body, The toner is the toner according to any one of claims 1 to 5. An image forming apparatus characterized by:

9. a charging step of charging an electrostatic latent image carrier; forming an electrostatic image on the charged electrostatic latent image carrier; a developing step of developing the electrostatic image with toner to form a toner image; a transfer step of transferring the toner image onto a transfer body; a cleaning step of cleaning the surface of the electrostatic latent image carrier after transfer with a cleaning member; a fixing step of fixing the toner image. The toner is the toner according to any one of claims 1 to 5. An image forming method comprising:

10. 10. The image forming method according to claim 9, further comprising a recycling system in which the toner collected from the surface of the electrostatic latent image carrier in the cleaning step is used as developing toner in the developing step.

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