Image forming system

Abstract

The invention relates to an image forming system. The image forming system includes a fixing means. The fixing means has an endless belt. A heating member; and an opposing member that fixes the toner on the recording medium conveyed by the endless belt at an opposing position. In the carbon number distribution obtained by gas chromatography, the mold release agent contains at least one minimum value of the carbon number in the range of 45-55 inclusive in the carbon number distribution, and the mold release agent contains at least one minimum value of the carbon number in the range of 45-55 inclusive in the carbon number distribution. When A1 is the minimum value and B1 is the maximum value in the range of 45 to 55 (inclusive) of carbon atoms, A1 / B1 is 0.70 or less.

Description

Technical Field

[0001] The present invention relates to an image forming system. Background Art

[0002] In recent years, among electrostatic image developing toners used in electrophotographic image forming apparatuses, the safety of carbon black contained in black electrostatic image developing toners has been considered a problem, and therefore black electrostatic image developing toners that do not contain carbon black are required. In addition, electrostatic image developing toners are required to have low-temperature fixing properties and paper discharge adhesion, and technologies for improving these properties have been disclosed (for example, refer to Patent Documents 1 and 2).

[0003] Patent Document 1 describes an image forming apparatus having a fixing device including a fixing belt, a heater, and a pressure roller. The fixing device is configured such that a heater as a heating member is disposed inside an endless fixing belt, and the pressure roller is pressed against the heater via the fixing belt. When a medium is passed through a nip formed between the outer circumferential surface of the fixing belt and the pressure roller, heat and pressure are applied to the toner image, thereby fixing the toner image to the medium.

[0004] Patent Document 2 describes a toner using two types of waxes. The toner described in Patent Document 2 contains an ester wax having high plasticity with respect to a binder resin during fixing, and a hydrocarbon wax having high releasability with respect to a fixing belt during fixing.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2022-01921

[0008] Patent Document 2: Japanese Patent Application Publication No. 2022-77719 Summary of the invention

[0009] Technical problem solved by the invention

[0010] The toner described in Patent Document 2 contains an ester wax with a relatively short carbon chain, and therefore is easily vaporized by the heat during fixing. Therefore, the wax vaporized by the heat during fixing solidifies in the air and may become particles (UFP: Ultra-Fine Particle) with a diameter of 100 nm or less.

[0011] It is believed that when the image forming apparatus described in Patent Document 1 uses the toner described in Patent Document 2, a heater is present near the nip portion, and therefore the wax solidified when the fixing air is cooled due to the generation of UFP adheres to the vicinity of the heater. As a result, the sliding property between the heater and the fixing belt is deteriorated, the driving of the fixing belt becomes unstable, and the fixing belt is damaged.

[0012] An object of the present invention is to provide an image forming system which suppresses the generation of UFP and has improved low-temperature fixing property and belt durability.

[0013] Technical means of solving problems

[0014] An image forming system according to one embodiment of the present invention is an image forming system for forming an image by fixing a colorant containing a release agent on a recording medium by a fixing means, wherein the fixing means comprises: an endless belt; a heating component arranged on the inner circumferential surface side of the endless belt; and an opposing component arranged on the outer circumferential surface side of the endless belt in a manner opposing the heating component via the endless belt, the fixing means fixing the colorant on the recording medium transported by the endless belt at the opposing position, and the release agent, in a carbon atom number distribution when the carbon atom number is set as the horizontal axis and the content as the vertical axis based on the results obtained by gas chromatography, contains at least one minimum value of the content within the range of carbon atoms greater than 45 and less than 55 in the carbon atom number distribution, and when the smallest of the minimum values ​​is set as A1 and the maximum value within the range of carbon atoms greater than 45 and less than 55 is set as B1, A1 / B1 is less than 0.70. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram used to illustrate the distribution of carbon atom numbers.

[0016] Figure 2 It is a cross-sectional view showing the structure of an image forming apparatus according to one embodiment of the present invention.

[0017] Figure 3 It is a cross-sectional view showing the structure of other fixing means. DETAILED DESCRIPTION

[0018] Hereinafter, an image forming system according to an embodiment of the present invention will be described in detail. First, a toner for developing an electrostatic image (toner) used in the image forming system will be described.

[0019] [Constitution of Toner for Electrostatic Image Development]

[0020] The colorant (toner) for electrostatic image development may be a one-component developer or a two-component developer. The toner in the case of a one-component developer is composed of toner particles. In addition, the toner in the case of a two-component developer is composed of toner particles and carrier particles. The toner particles are composed of toner matrix particles and external additives attached to the surface thereof. In the present embodiment, the toner is preferably a two-component developer.

[0021] Examples of carrier particles when the toner is used as a two-component developer include magnetic particles made of conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead. The carrier particles are preferably ferrite particles.

[0022] Examples of carrier particles include resin-coated carriers having a core material and a resin coating layer on the surface of the core material, and magnetic dispersion type carriers. In addition, the carrier particles may be resin dispersion type carriers in which a conductive material or the like is dispersed in a matrix resin.

[0023] Examples of the coating resin forming the resin coating layer used in the carrier particles include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid copolymer, straight silicone resin containing an organic siloxane bond or its modified product, fluororesin, polyester resin, polycarbonate, phenolic resin, epoxy resin.

[0024] In addition, examples of the core material of the carrier particles include: magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. The core material of the carrier particles is preferably a magnetic material in order to use the carrier particles in the magnetic brush method. The volume average particle size of the core material of the carrier particles is preferably in the range of 10 to 200 μm, and more preferably in the range of 25 to 100 μm.

[0025] In addition, the method of coating the surface of the core material of the carrier particles with resin includes: a method of coating by dissolving the coating resin and various additives as needed in a coating layer forming solution in an appropriate solvent. The solvent is not particularly limited and can be appropriately selected in consideration of the coating resin used, coating adaptability, etc.

[0026] The average particle size of the carrier particles is preferably 15 to 150 μm, more preferably 15 to 100 μm, and particularly preferably 25 to 80 μm in terms of volume-based median particle size. The volume-based median particle size of the carrier particles can be measured, for example, by a laser diffraction particle size distribution measuring device (HELOS; SYMPATEC) equipped with a wet disperser.

[0027] The mixing ratio (mass ratio) of the toner particles and the carrier particles is not particularly limited, but is preferably toner particles:carrier particles=1:100 to 30:100, more preferably 3:100 to 20:100, from the viewpoint of charging properties and storage stability.

[0028] The toner parent particle in this embodiment has a core portion arranged inside and a shell portion arranged so as to cover the surface of the core portion. The core portion has a continuous layer and a dispersion layer dispersed in the continuous layer. The continuous layer is a binder resin, and the dispersion layer contains a release agent. The toner parent particle has a core-shell structure, so that low-temperature fixability and heat-resistant storage performance can be ensured.

[0029] (Binder resin)

[0030] The binder resin preferably includes a polyester resin (crystalline resin). In the present embodiment, the binder resin includes a polyester resin and an amorphous resin. The polyester resin is preferably a crystalline polyester resin. Here, the crystalline polyester resin includes both a modified resin consisting only of a polyester polymer segment and a modified resin in which other components are combined at a ratio of 50% by mass or less. In addition, the other components combined with the polyester polymer segment are preferably vinyl polymer segments.

[0031] The crystalline polyester resin is a known polyester resin obtained by a polycondensation reaction of a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyol), and is a resin having no step-like endothermic change and a clear endothermic peak in differential scanning calorimetry (DSC) of the crystalline resin or toner base particles. Specifically, the clear endothermic peak refers to a peak whose half-value width of the endothermic peak is within 15°C when measured at a heating rate of 10°C / min in DSC.

[0032] The melting point (Tmc-A) of the crystalline polyester resin is preferably in the range of 60 to 90°C, and more preferably in the range of 70 to 80°C, from the viewpoint of obtaining sufficient low-temperature adhesion and good heat-resistant storage properties. When the melting point of the crystalline polyester resin is in the range of 60 to 90°C, low-temperature fixability is not hindered, and heat-resistant storage properties are improved. The melting point (Tmc-A) can be measured by DSC. DSC measurement is performed by differential scanning calorimetry analysis using a differential scanning calorimeter (DSC7000X; Hitachi, Ltd.) and a thermal analyzer controller (AS3 / DX; Hitachi, Ltd.). Specifically, 5 mg of the measurement sample is placed in a sample container for an AL automatic sampler. H2.5mm (Hitachi, Ltd.), sealed with AL autosampler cover (Hitachi, Ltd.), installed in the sample holder of the thermal analysis device controller, under the measurement conditions of 0-100°C, heating rate 10°C / min, cooling rate 10°C / min, heating-cooling-heating (Heat-Cool-Heat), the analysis was performed based on the data in the first heating (1st.heat). An empty aluminum pan was used for control measurement. The peak top temperature of the peak appearing on the lowest temperature side of the wax-derived exothermic peak in the first heating is set as Tcp-A1 (°C), and the other peak top temperature is set as Tcp-A2 (°C).

[0033] "Polycarboxylic acid" means a compound containing two or more carboxyl groups in one molecule. Examples of divalent carboxylic acids containing two carboxyl groups in one molecule include oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydro Terephthalic acid, malonic acid, pimelic acid, tartaric acid, mucic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, terephthalic acid, m-phenylene diglycolic acid, p-phenylene diglycolic acid, o-phenylene diglycolic acid, diphenylacetic acid, diphenyl-p,p′-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, dodecenylsuccinic acid.

[0034] Examples of the polyvalent carboxylic acid other than the divalent carboxylic acid include trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.

[0035] “Polyol” means a compound containing two or more hydroxyl groups in one molecule. Examples of divalent polyols containing two hydroxyl groups in one molecule include ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, ethylene oxide addition products of bisphenol A, and propylene oxide addition products of bisphenol A. In addition, examples of polyols other than divalent polyols include glycerol, pentaerythritol, hexamethylolmelamine, hexamethylolmelamine, tetramethylolbenzoguanamine, and tetramethylolbenzoguanamine.

[0036] The method for producing the crystalline polyester resin is not particularly limited, and the crystalline polyester resin can be produced by polycondensing (esterifying) a polycarboxylic acid and a polyol using a known esterification catalyst. Examples of the esterification catalyst include: titanium acetate, titanium propionate, titanium caproate, titanium octanoate and other aliphatic titanium monocarboxylates; titanium oxalate, titanium succinate, titanium maleate, titanium adipate, titanium sebacate and other aliphatic titanium dicarboxylates; titanium hexane tricarboxylates, isooctane tricarboxylates and other aliphatic titanium carboxylates; titanium octane tetracarboxylates, titanium decane tetracarboxylates and other aliphatic titanium carboxylates; titanium aromatic monocarboxylates such as titanium benzoate; titanium phthalate, titanium terephthalate, titanium isophthalate, titanium naphthalene dicarboxylates, titanium biphenyl dicarboxylates, titanium anthracene dicarboxylates and other aromatic titanium dicarboxylates. Titanium carboxylates; aromatic titanium tricarboxylates such as titanium trimellitate and titanium naphthalene tricarboxylate; aromatic titanium carboxylates such as titanium benzene tetracarboxylate and titanium naphthalene tetracarboxylate; aliphatic titanium carboxylates, oxytitanium compounds of aromatic titanium carboxylates and their alkali metal salts; titanium halides such as titanium dichloride, titanium trichloride, titanium tetrachloride, titanium tetrabromide; tetraalkoxy titanium such as tetrabutoxytitanium (titanium tetrabutoxide), tetraoctyloxytitanium, tetrastearateoxytitanium, titanium acetylacetonate, diisopropyl diacetylacetonate titanate, titanium triethanolamine and other titanium-containing catalysts.

[0037] The content of the crystalline polyester resin relative to the binder resin is preferably in the range of 3 to 30% by mass, and more preferably in the range of 5 to 20% by mass. When the content of the crystalline polyester resin relative to the binder resin is less than 3% by mass, there is a risk that the low-temperature fixability becomes insufficient. On the other hand, when the content of the crystalline polyester resin relative to the binder resin is higher than 30% by mass, there is a risk that it becomes difficult to crystallize in the toner, the heat-resistant storage property is reduced, and the effect of suppressing the discharge adhesion cannot be fully exerted.

[0038] Amorphous resin is the main component of the binder resin. Examples of amorphous resins include vinyl resins such as olefin resins, styrene resins, acrylic resins, and styrene acrylic copolymer resins, amorphous polyester resins, polyamide resins, polycarbonate resins, polyether resins, polyvinyl acetate resins, polysulfone resins, epoxy resins, polyurethane resins, and urea-formaldehyde resins. As for amorphous resins, amorphous polyester resins are preferred from the viewpoints of fixability, heat-resistant storage of toners, and heat resistance of fixed images. Amorphous resins can be used alone or in combination of two or more.

[0039] Monomers for forming vinyl resins such as styrene resins, acrylic resins, and styrene acrylic copolymer resins include vinyl monomers. Examples of vinyl monomers include styrene monomers, (meth)acrylate monomers, vinyl esters, vinyl ethers, vinyl ketones, N-vinyl compounds, and other vinyl compounds. The vinyl monomers may be used alone or in combination of two or more.

[0040] Examples of the styrene-based monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, and derivatives thereof.

[0041] The content of styrene monomers in the toner is preferably 0.2% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less. In addition, with respect to the content of styrene monomers in the toner, by the presence of a small amount of styrene monomers having a higher hydrophobicity than the polyester resin, the hydrophobic wax can be uniformly dispersed in the toner and exists in the state of particles. In the case where the content of styrene monomers in the toner is small, the hydrophilicity in the toner is high, and the short-chain length and long-chain length waxes (release agents) volatilized during fixing cannot be mixed, and the generation of UFP cannot be suppressed. On the other hand, in the case where the content of styrene monomers in the toner is large, the hydrophobicity in the toner becomes high, and the waxes (release agents) become easy to exist with each other, and exist as larger particles. Therefore, it becomes difficult to melt during fixing, especially in the case where the long-chain length wax does not melt and the effect of the present application cannot be exerted.

[0042] The styrene content in the toner can be measured by a known method. The styrene content in the toner can be measured using thermal decomposition GC / MS. Specifically, a chloroform solution of 2000 mg / L of the toner is used in the measurement. The peak of St at 8.5 min in the obtained chromatogram can be quantified by an absolute calibration curve method. At this time, the thermal decomposition temperature is 600°C, and the column can use UA-5 (MS / HT)-30M-0.25F (30m×0.25mm×0.25μm).

[0043] Examples of (meth)acrylate monomers include: methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, phenyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and derivatives thereof.

[0044] Examples of vinyl esters include vinyl propionate, vinyl acetate, and vinyl benzoate. Examples of vinyl ethers include vinyl methyl ether and vinyl ethyl ether. Examples of vinyl ketones include vinyl methyl ketone, vinyl ethyl ketone, and vinyl hexyl ketone. Examples of N-vinyl compounds include N-vinyl carbazole, N-vinyl indole, and N-vinyl pyrrolidone. Examples of other vinyl compounds include vinyl naphthalene and vinyl pyridine. In addition, examples of other amorphous resins include acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.

[0045] The vinyl monomer is preferably a monomer having an ionic dissociative group such as a carboxyl group, a sulfonic acid group, or a phosphoric acid group. Examples of monomers having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl esters, and itaconic acid monoalkyl esters. In addition, examples of monomers having a sulfonic acid group include styrene sulfonic acid, allyl sulfosuccinic acid, and 2-acrylamide-2-methylpropane sulfonic acid. Examples of monomers having a phosphoric acid group include acid phosphoxy ethyl methacrylate.

[0046] In addition, as the vinyl monomer, a multifunctional vinyl is used, and a vinyl resin having a cross-linked structure may also be used. Examples of the multifunctional vinyl include divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, and neopentyl glycol diacrylate.

[0047] The amorphous polyester resin is a known polyester resin obtained by a polycondensation reaction of a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyol), and does not show a clear endothermic peak in differential scanning calorimetry (DSC).

[0048] The polycarboxylic acid means a compound containing two or more carboxyl groups in one molecule. Examples of the polycarboxylic acid include saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene dicarboxylic acid; unsaturated aliphatic dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, isododecenylsuccinic acid, n-dodecenylsuccinic acid, and n-octenylsuccinic acid; and trivalent or higher polycarboxylic acids such as trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid. The polyvalent carboxylic acid can be used alone or in combination of two or more.

[0049] Polyol means a compound containing two or more hydroxyl groups in one molecule. Examples of polyols include aliphatic diols such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosandiol; bisphenols such as bisphenol A and bisphenol F and their ethylene oxide addition products, propylene oxide addition products and other alkylene oxide addition products of bisphenols; and trivalent or higher polyols such as glycerol, pentaerythritol, hexamethylolmelamine, hexamethylolmelamine, tetramethylolbenzoguanamine, and tetramethylolbenzoguanamine. The polyol can be used alone or in combination of two or more.

[0050] Regarding the ratio of the polycarboxylic acid to the polyol, the equivalent ratio [OH] / [COOH] of the hydroxyl group (-OH) of the polyol to the carboxyl group (-COOH) of the polycarboxylic acid is preferably in the range of 1.5 / 1 to 1 / 1.5, more preferably in the range of 1.2 / 1 to 1 / 1.2.

[0051] The number average molecular weight of the amorphous polyester resin is preferably in the range of 2000 to 10000. In addition, the glass transition temperature of the amorphous polyester resin is preferably in the range of 20 to 70° C. The glass transition temperature of the amorphous polyester resin can be measured in the same manner as the glass transition temperature of the amorphous vinyl resin.

[0052] The amorphous polyester resin may be a mixed resin modified by a styrene-acrylic resin. In the case of the amorphous polyester resin as a mixed resin, the styrene-acrylic resin part has high compatibility with the amorphous vinyl resin, and the amorphous polyester resin can be uniformly dispersed in the toner matrix particles. In the case where the toner particles have a core-shell structure and the shell layer contains the amorphous polyester resin, it is easy to aggregate on the surface of the core particles containing the amorphous vinyl resin, and it becomes easy to cover the entire surface.

[0053] The amorphous polyester resin modified by the styrene-acrylic resin means a resin in which the unit of the amorphous polyester resin and the unit of the styrene-acrylic resin are chemically bonded. Here, the "unit of the amorphous polyester resin" means the resin part derived from the amorphous polyester resin in the mixed resin, that is, the molecular chain having the same chemical structure as the amorphous polyester resin. In addition, the "unit of the styrene-acrylic resin" means the resin part derived from the styrene-acrylic resin in the mixed resin, that is, the molecular chain having the same chemical structure as the styrene-acrylic resin.

[0054] Styrene-acrylic resin is a polymer of a styrene monomer and a (meth)acrylic monomer. Examples of styrene monomers include: styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, 2,4-dimethylstyrene, 3,4-dichlorostyrene, and derivatives thereof. These styrene monomers may be used alone or in combination of two or more.

[0055] Examples of the (meth)acrylic monomer include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, 6-hydroxyethyl acrylate, γ-aminopropyl acrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. These (meth)acrylic monomers may be used alone or in combination of two or more.

[0056] Styrene-acrylic resins may use other monomers in addition to styrene monomers and (meth)acrylic monomers. Examples of other monomers that may be used include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl esters, itaconic acid monoalkyl esters, (meth) acrylate 2-hydroxyethyl, (meth) acrylate 2-hydroxypropyl, (meth) acrylate 3-hydroxypropyl, (meth) acrylate 2-hydroxybutyl, (meth) acrylate 3-hydroxybutyl, (meth) acrylate 4-hydroxybutyl, (meth) acrylate, polyethylene glycol mono(meth) acrylate, and the like.

[0057] Styrene-acrylic resin can be obtained by adding any commonly used polymerization initiator such as peroxide, persulfide, azo compound, etc. to the polymerization of the monomers, and polymerizing by known polymerization methods such as bulk polymerization, solution polymerization, emulsion polymerization, microemulsion polymerization, suspension polymerization, dispersion polymerization, etc. In addition, during polymerization, commonly used chain transfer agents such as alkyl mercaptan and mercapto fatty acid esters can be used from the viewpoint of regulating molecular weight.

[0058] The content of the styrene-acrylic resin unit in the mixed resin is preferably within a range of 1 to 30% by mass from the viewpoint of easily controlling the plasticity of the toner base particles.

[0059] The mixed resin can be obtained by reacting the amorphous polyester resin and the styrene-acrylic resin prepared separately to chemically bond. From the viewpoint of easy bonding, it is preferred to introduce a substituent capable of reacting with both the amorphous polyester resin and the styrene-acrylic resin into the amorphous polyester resin or the styrene-acrylic resin. For example, when the styrene-acrylic resin is produced, a compound having a substituent capable of reacting with the carboxyl group or hydroxyl group of the amorphous polyester resin and a substituent capable of reacting with the styrene-acrylic resin is added while adding the styrene monomer and the (meth) acrylic monomer as raw materials. Thus, a styrene-acrylic resin having a substituent capable of reacting with the carboxyl group or hydroxyl group in the amorphous polyester resin can be obtained.

[0060] In addition, the mixed resin can be obtained by carrying out a polymerization reaction to produce a styrene-acrylic resin in the presence of a pre-prepared amorphous polyester resin, or by carrying out a polymerization reaction to produce an amorphous polyester resin in the presence of a pre-prepared styrene-acrylic resin. In either case, when carrying out the polymerization reaction, a compound having a substituent that can react with both the amorphous polyester resin and the styrene-acrylic resin as described above can be added.

[0061] The number average molecular weight of the mixed resin is preferably in the range of 2000 to 10000 from the viewpoint of fixability. The content of the amorphous polyester resin in the toner base particles is preferably in the range of 1 to 50% by mass from the viewpoint of fixability and environmental stability of charging.

[0062] The content of the amorphous resin in the binder resin is preferably in the range of 70 to 95% by mass. When the content of the amorphous resin is in the above range, when used together with the crystalline polyester resin as a binder resin, sufficient low-temperature fixing property, sufficient heat-resistant storage property of the toner, and heat resistance of the fixed image can be ensured.

[0063] (Release Agent)

[0064] In the toner of the present invention, with respect to the release agent, based on the results obtained by gas chromatography, in the carbon number distribution when the horizontal axis is the carbon number and the vertical axis is the content, in the range of carbon number of 45 or more and 55 or less in the carbon number distribution, at least one minimum value of the content is included, the smallest minimum value is set as A1, and the maximum value in the range of carbon number of 45 or more and 55 or less is set as B1, A1 / B1 is 0.70 or less. Thus, an image forming system having low temperature fixability and belt durability while suppressing the generation of UFP can be provided. The mechanism of exerting the effect of the present invention is presumed as follows.

[0065] The easily plasticizable wax which is excellent in low-temperature fixing is easily vaporized by the heat of fixing when it is excessively heated at a relatively low melting temperature. The vaporized wax resolidifies in the air in the device to generate UFP.

[0066] In the case of a fixing machine with a heat source in the clamping part, the high-temperature heat energy in the colorant takes a certain amount of time, so it is excellent in fixing properties, but UFP is easily generated. The solidified wax adheres to the vicinity of the heat source during cooling during fixing, deteriorating the sliding properties of the heat source and the belt, making the belt drive unstable and causing the belt to be damaged.

[0067] The release agent contained in the toner of the present invention has a minimum value in the range of 45 to 55 carbon atoms when analyzed by gas chromatography. This means that release agents with different carbon atoms are contained. Release agents with smaller carbon atoms, i.e., shorter chain lengths, are excellent in low-temperature fixability, but are prone to UFP generation. Therefore, it is believed that by containing a release agent with a larger carbon number, i.e., a longer chain length, the chain portion of the release agent is entangled with the chain portion of the release agent with a smaller carbon number, and the gasification of the release agent with a smaller carbon number can be suppressed.

[0068] When A1 / B1 is 0.70 or less, the generation of UFP can be suppressed while ensuring low-temperature fixing properties.

[0069] The release agent is a wax contained in order to ensure the fixing separation property of the toner. The release agent may be an ester wax or a hydrocarbon wax. The release agent may be a synthetic one or a commercially available one purified one. An example of a method for purifying the release agent includes a method of dissolving in n-hexane or heptane and then recrystallizing. In addition, two or more release agents may be used in combination, or three or more release agents may be used in combination.

[0070] Examples of the ester wax include carnauba wax, montan wax, behenyl behenate, trimethylolpropane tribehenyl, pentaerythritol tetrabehenyl, pentaerythritol diacetate dibehenyl, glyceryl behenate, 1,18-octadecanediol distearate, tristearyl trimellitate, and distearyl maleate.

[0071] Examples of the hydrocarbon wax include polyolefin waxes such as polyethylene wax and polypropylene wax, petroleum-derived paraffin wax, microcrystalline wax, Fischer-Tropsch wax as a synthetic wax, and polyethylene wax.

[0072] The carbon chains of the two or more release agents are not particularly limited as long as the carbon number of the carbon atoms in the carbon atom number distribution is within the range of 45 to 55, and the minimum value A1 is 0.7 or less relative to the maximum value B1. In this way, the generation of UFP during the fixing of the toner can be suppressed by having a release agent with a longer carbon chain and a release agent with a shorter carbon chain.

[0073] The content of the release agent in the toner particles is preferably in the range of 7 to 15 mass %, more preferably in the range of 7.5 to 10 mass %. When the content of the release agent in the toner particles is in the above range, both the releasability and the heat-resistant storage property can be achieved.

[0074] The method of extracting the release agent from the toner can use a known method. Examples of the extraction method include: solid-liquid extraction method, a method of separating the toner by centrifugal separation after dissolving or swelling the toner, Soxhlet extraction method, and high-speed solvent extraction method. It can be selected according to the type of saturated hydrocarbon compound, the type of compound that becomes an impurity component such as the binder resin of the toner. As for the solvent used in the extraction, n-hexane is preferably used from the solubility of the extracted release agent. As for the solvent, polar solvents such as dichloromethane and ethanol can be used in combination according to the polarity and molecular weight of the binder resin in order to swell the binder resin and improve the efficiency of the extraction. GC / FID can be used for the determination of the carbon chain distribution in the release agent. A xylene solution of 500 to 1000 mg / L of the release agent can be used in the measurement. The analysis device can use GC-2010Plus FID (Shimadzu Corporation). The column that can be used is Ultra ALLOY-SIMDIS (HT) (5 m×0.53 mm×0.1 μm) (FRONTIER LABORATORIES Co., Ltd.), and the column temperature can be 50° C. to 400° C. (20° C. / min), or -400° C. (10 min).

[0075] Here, the analysis results of the toner containing the release agent in the present embodiment by gas chromatography will be described. The solid-liquid extraction method was used to extract the release agent from the toner.

[0076] Figure 1 This is a schematic diagram for explaining an example of the results of analyzing the release agent by gas chromatography. Figure 1 The horizontal axis represents the average number of carbon atoms per molecule of the release agent, and the vertical axis represents the content (μV). Figure 1 The solid line in shows a curve corresponding to the function representing the distribution of the number of carbon atoms, and the dotted line shows a base line. The results of analyzing the release agent by gas chromatography can be analyzed, for example, as follows.

[0077] For example, by analyzing the release agent by GC-FID (hydrogen flame ionization detector), the content of the release agent relative to the dissolution time is obtained. On the other hand, using a reference material with a known carbon number (for example, a hydrocarbon (alkane) mixed sample GL SCIENCES Co., Ltd. with a carbon number of 9-40), it is analyzed by GC-FID in the same manner. From the analysis results of the release agent and the analysis results of the reference material, the relationship between the carbon number and the dissolution time is obtained. Then, the dissolution time of the analysis results of the release agent is replaced by the carbon number. Thus, a chart with the horizontal axis as the carbon number and the vertical axis as the content can be obtained. It should be noted that the baseline is the value obtained by GC-FID without containing the sample. In addition, A1 and B1, as well as A2 and B2 below, can be obtained by subtracting the value of the baseline from the content.

[0078] Next, a method for obtaining the maximum value and the minimum value of the content in the carbon number distribution is described. The minimum value and the maximum value of the content can be obtained by, for example, the following method. The point where the slope of the tangent line in the curve changes from negative to positive represents the minimum value in the carbon number distribution.

[0079] That is, the point where the slope of the tangent line in the curve corresponding to the function representing the distribution of the number of carbon atoms changes from positive to negative represents the maximum point in the distribution of the number of carbon atoms.

[0080] In the present embodiment, the release agent, based on the results obtained by gas chromatography, sets the carbon number as the horizontal axis and the content as the vertical axis in the carbon number distribution, contains at least one minimum value of the content within the range of 45 to 55 carbon atoms in the carbon number distribution. And, when the smallest minimum value is set to A1 and the maximum value within the range of 45 to 55 carbon atoms is set to B1, A1 / B1 is less than 0.70, preferably less than 0.5. In this way, A1 / B1 is less than 0.70, which means that at least 2 release agents are included. Here, the 2 release agents are a release agent with a larger number of carbon atoms in the carbon chain and a release agent with a smaller number of carbon atoms in the carbon chain.

[0081] In addition, in the carbon number distribution, when the total value of the content in the range of 30 or more and less than 50 carbon atoms is set as A2, and the total value of the content in the range of 50 or more and 60 or less carbon atoms is set as B2, A2 / B2 is preferably 2.0 or more and 6.0 or less, and more preferably 2.0 or more and 4.0 or less. In this way, in the present embodiment, the content of the release agent with a larger number of carbon atoms is greater than that of the release agent with a smaller number of carbon atoms. When A2 / B2 is not within the range, the release agent with a larger number of carbon atoms and the release agent with a smaller number of carbon atoms cannot be properly mixed, so there is a risk of a large number of UFPs being generated.

[0082] In addition, in the carbon number distribution, in the range of less than 44 carbon atoms and more than 56 carbon atoms, it is preferred to have more than one maximum value. The number of maximum values ​​is not particularly limited. The number of maximum values ​​can be one or more. In the present embodiment, in the carbon number distribution, in the range of less than 44 carbon atoms and more than 56 carbon atoms, there is one maximum value. In the range of less than 44 carbon atoms and more than 56 carbon atoms, there is one maximum value, which means that there are two types of release agents.

[0083] The toner matrix particles are of a core-shell structure as described above. Here, "core-shell structure" means a structure having a core portion arranged inside and a shell portion covering the surface of the core portion. Here, "covering the core portion" means that the entire core portion does not necessarily have to be covered, and it is sufficient to cover it to the extent that the function of the conductive polymer can be exerted. The toner matrix particles of the core-shell structure have: a resin particle (core portion) with a relatively low glass transition temperature containing a colorant, a release agent, etc., and a resin region (shell portion) with a relatively high glass transition temperature on the surface of the core portion. In terms of the core-shell structure, the shell portion may completely cover the core portion, or the shell portion may not completely cover the core portion, and a portion of the core portion may be exposed. It should be noted that the shell portion may be condensed on the surface of the core portion and manufactured by fusing it. The cross-sectional structure of the core-shell structure can be confirmed by known means such as a transmission electron microscope (TEM: Transmission Electron Microscope) and a scanning probe microscope (SPM: Scanning Probe Microscope).

[0084] Examples of the resin constituting the shell include amorphous polyester resins and vinyl resins. The resin constituting the shell preferably has an alkyl unit derived from one or more compounds selected from aliphatic monocarboxylic acids having 10 to 30 carbon atoms or aliphatic monoalcohols having 10 to 30 carbon atoms.

[0085] The content of the shell part in the toner matrix particles is preferably 5 to 30% by mass. When the content of the shell part in the toner matrix particles is less than 5% by mass, there is a risk that the coverage of the core part is reduced, the conductive polymer is exposed on the surface of the toner, and the required charge amount as a developer cannot be maintained. In addition, when the content of the shell part in the toner matrix particles exceeds 30% by mass, there is a risk that the low-temperature fixability becomes low.

[0086] The toner matrix particles contain a colorant. The colorant may be a known dye or pigment. Examples of the colorant used to obtain a black toner include carbon black such as furnace black and channel black, magnetic materials such as magnetite and ferrite, dyes, and inorganic pigments including non-magnetic iron oxide.

[0087] As examples of the colorant for obtaining a color toner, any known colorant such as a dye and an organic pigment can be used. Specifically, examples of the organic pigment include CI Pigment Red 5, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 81:4, CI Pigment Red 122, CI Pigment Red 139, CI Pigment Red 144, CI Pigment Red 149, CI Pigment Red 166, CI Pigment Red 177, CI Pigment Red 178, CI Pigment Red 222, CI Pigment Red 238, CI Pigment Red 269, CI Pigment Yellow 14, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 138, CI Pigment Yellow 155, CI Pigment Yellow 180, CI Pigment Yellow 185, CI Pigment Orange 31, CI Pigment Orange 43, CI Pigment Blue 15:3, CI Pigment Blue 60, CI Pigment Blue 76.

[0088] Examples of dyes include CI Solvent Red 1, CI Solvent Red 49, CI Solvent Red 52, CI Solvent Red 58, CI Solvent Red 68, CI Solvent Red 11, CI Solvent Red 122, CI Solvent Yellow 19, CI Solvent Yellow 44, CI Solvent Yellow 77, CI Solvent Yellow 79, CI Solvent Yellow 81, CI Solvent Yellow 82, CI Solvent Yellow 93, CI Solvent Yellow 98, CI Solvent Yellow 103, CI Solvent Yellow 104, CI Solvent Yellow 112, CI Solvent Yellow 162, CI Solvent Blue 25, CI Solvent Blue 36, CI Solvent Blue 69, CI Solvent Blue 70, CI Solvent Blue 93, CI Solvent Blue 95.

[0089] The colorant used to obtain the toner of various colors may be used alone or in combination of two or more for each color. The content of the colorant is preferably in the range of 1 to 20 parts by mass, more preferably in the range of 4 to 15 parts by mass, relative to 100 parts by mass of the binder resin.

[0090] The external additive is used to improve the fluidity of the toner, the charging property of the toner, the cleaning property, etc. Examples of the external additive include so-called fluidizing agents and cleaning aids. As for the external additive, various external additives can be used in combination. The total addition ratio of the external additive is preferably in the range of 0.05 to 5 parts by mass, and more preferably in the range of 0.1 to 3 parts by mass, relative to 100 parts by mass of the toner particles.

[0091] As for the melting point (Tmc-B) of the colorant, from the viewpoint of obtaining sufficient low-temperature adhesion and good heat-resistant storage performance, it is preferably in the range of 60 to 90°C. When the melting point of the colorant is in the range of 60 to 90°C, it does not hinder the low-temperature fixability and improves the heat-resistant storage performance. The melting point (Tmc-B) can be measured by DSC. In the present embodiment, when the colorant is subjected to differential scanning calorimetry, two peaks (Tcp1 (°C), Tcp2 (°C)) are preferably present between 60 and 90°C. DSC measurement is performed using a differential scanning calorimeter (DSC7000X; Hitachi, Ltd.) and a thermal analyzer controller (AS3 / DX; Hitachi, Ltd.) and by differential scanning calorimetry analysis. Specifically, 5 mg of the measurement sample is placed in a sample container for an AL automatic sampler. H2.5mm (Hitachi, Ltd.), sealed with an AL autosampler cover (Hitachi, Ltd.), installed in the sample holder of the thermal analysis device controller, under the measurement conditions of 0-100°C, a heating rate of 10°C / min, and a cooling rate of 10°C / min, the temperature control of heating-cooling-heating (Heat-Cool-Heat) was performed, and the data in the first heating (1st.heat) was analyzed. An empty aluminum pan was used in the control measurement. The peak top temperature of the peak that appeared on the lowest temperature side of the exothermic peak derived from the release agent in the first heating was set as Tcp-B1 (°C), and the other peak top temperature was set as Tcp-B2 (°C).

[0092] [Characteristics of Toner for Electrostatic Image Development]

[0093] (Toner particle size)

[0094] The average particle size of the toner is preferably in the range of 3 to 10 μm, more preferably in the range of 5 to 8 μm, based on the volume-based median particle size. As for the average particle size, the volume-based median particle size that can be controlled according to the concentration of the coagulant used in the production, the amount of the organic solvent added, the welding time, the composition of the binder resin, etc. is within the above range, and very fine dot images at the 1200 dpi level can be faithfully reproduced.

[0095] The volume-based median particle size can be measured using a measuring device connected to a computer system equipped with data processing software V3.51, MULTISIZER3 (BECKMAN COULTER). Specifically, 0.02 g of toner is added to 20 mL of a surfactant solution (for example, a surfactant solution prepared by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles) and mixed, and then subjected to ultrasonic dispersion treatment for 1 minute to prepare a toner dispersion. The toner dispersion is injected into a beaker containing ISOTONII (BECKMAN COULTER) in the sample stage through a pipette until the concentration indicated by the measuring device becomes 8%. By adjusting to this concentration, a reproducible measurement value can be obtained. Next, in the measuring device, the particle count is set to 25,000, the aperture is set to 100 μm, the measurement range of 2 to 60 μm is divided into 256 parts to calculate the frequency value, and the 50% particle size is determined as the volume-based median particle size from the side with the larger volume cumulative fraction.

[0096] (Average Circularity of Toner Particles)

[0097] The average circularity of the toner particles is preferably in the range of 0.930 to 1.000, and more preferably in the range of 0.950 to 0.995. If the average circularity is within the above range, each toner particle becomes difficult to break, the contamination of the friction charging imparting component is suppressed, the charging property of the toner is stabilized, and the image formed by the toner becomes high-quality.

[0098] The average circularity of the colorant can be measured, for example, in the following manner. In the same manner as in the case of measuring the median particle size, a dispersion of the colorant is prepared. The dispersion of the colorant is photographed in the HPF (high magnification photography) mode using FPIA-2100, FPIA-3000 (both from Sysmex) or the like within an appropriate concentration range of 3,000 to 10,000 HPF detection numbers, and the circularity of each colorant particle is calculated using the following formula (y). The average circularity is calculated by adding the circularity of each colorant particle and dividing the sum of the circularities by the number of each colorant particle. When the HPF detection number is within the appropriate concentration range, sufficient reproducibility can be obtained. It should be noted that, in the present embodiment, the average circularity of the colorant and the average circularity of the colorant particles are approximately the same value.

[0099] Formula(y)

[0100] Circularity = (circumference of a circle with the same projected area as the particle image) / (circumference of the particle projection image)

[0101] [Method for producing toner]

[0102] The method for producing the toner of the present invention is not particularly limited. Examples of the method for producing the toner include: a pulverization method, an emulsion dispersion method, a suspension polymerization method, a dispersion polymerization method, an emulsion polymerization method, an emulsion polymerization coagulation method, and other known methods. From the viewpoint of production cost and production stability, the method for producing the toner is preferably an emulsion polymerization coagulation method.

[0103] In a method for manufacturing a colorant based on an emulsion polymerization coagulation method, an aqueous dispersion in which binder resin particles (hereinafter also referred to as "binder resin particles") are dispersed in an aqueous medium and an aqueous dispersion in which colorant particles (hereinafter also referred to as "colorant particles") are mixed, and the binder resin particles and the colorant particles are coagulated / thermally melted to form colorant particles and prepare the colorant.

[0104] The adhesive resin particles may have a multilayer structure of more than two layers composed of adhesive resins of different compositions. For example, the adhesive resin particles having such a composition, having a two-layer structure, are obtained by the following method: adjusting the dispersion of the resin particles by polymerization treatment (first stage polymerization) according to a conventional method, adding a polymerization initiator and a polymerizable monomer to the dispersion, and subjecting the system to polymerization treatment (second stage polymerization).

[0105] Here, "aqueous dispersion" means that the dispersion (particles) are dispersed in an aqueous medium, and the aqueous medium means a medium whose main component (50% by mass or more) is water. Examples of components other than water include organic solvents soluble in water, including methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Components other than water are preferably alcohol organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin.

[0106] The emulsion polymerization coagulation method is a method of forming colorant particles by mixing a binder resin particle dispersion obtained by dispersing a binder resin in an aqueous medium and a colorant particle dispersion obtained by dispersing a colorant in an aqueous medium, thereby causing the binder resin particles and the colorant particles to coagulate and fuse in the aqueous medium.

[0107] (Step of Preparing Resin Particle Dispersion)

[0108] A non-crystalline resin (or crystalline resin as needed) is dispersed in an aqueous medium to prepare an amorphous resin particle dispersion (crystalline resin particle dispersion). An aqueous medium refers to a medium having a water content of 50% by mass or more. Examples of components other than water include organic solvents such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran that are soluble in water. Components other than water are preferably alcohol organic solvents such as methanol, ethanol, isopropanol, and butanol that are organic solvents that do not dissolve resins.

[0109] The method for manufacturing amorphous resin (crystalline resin) is not particularly limited, and an emulsion polymerization method can be used in which a monomer of the resin is added to an aqueous medium together with a polymerization initiator, the monomer is subjected to a polymerization reaction, and a dispersion of resin particles is obtained. In the emulsion polymerization method, the polymerization reaction can be carried out in multiple stages. For example, in the case of a polymerization reaction in three stages, a dispersion of resin particles is prepared by polymerization in the first stage, and a monomer of the resin and a polymerization initiator are further added to the dispersion to perform polymerization in the second stage. To the dispersion prepared by the second stage polymerization, a monomer of the resin and a polymerization initiator are further added to perform polymerization in the third stage. During the polymerization in the second and third stages, the resin particles in the dispersion obtained by the previous polymerization can be used as seeds, and the monomer newly added to the resin particles can be further polymerized to achieve uniformity of the particle size of the resin particles. In addition, during the polymerization reaction in each stage, by using different monomers, the structure of the resin particles can be made into a multilayer structure, and resin particles with target properties can be easily obtained.

[0110] The method for preparing the dispersion is not limited to the emulsion polymerization method. A phase inversion emulsification method can be used in which a resin is dissolved or dispersed in an organic solvent to prepare an oil phase liquid, and the oil phase liquid is subjected to phase inversion emulsification to disperse oil droplets of a target particle size in an aqueous medium.

[0111] (Polymerization initiator)

[0112] As a polymerization initiator that can be used for the polymerization reaction, a known substance can be used. Examples of polymerization initiators include persulfates such as ammonium persulfate, sodium persulfate, potassium persulfate, 2,2'-azobis(2-aminobispropane) hydrochloride, 2,2'-azobis-(2-aminobispropane) nitrate, 4,4'-azobis-4-cyanovaleric acid, poly(tetraethylene glycol-2,2'-azobisisobutyrate), peroxides such as hydrogen peroxide, etc. The amount of polymerization initiator added varies according to the target molecular weight and molecular weight distribution. Specifically, it is preferably within the range of 0.1 to 5.0% by mass relative to the amount of polymerizable monomer added.

[0113] (Chain transfer agent)

[0114] During the polymerization reaction, a chain transfer agent is added from the viewpoint of controlling the molecular weight of the resin particles. Examples of the chain transfer agent include mercaptans such as octyl mercaptan, mercaptopropionic acids such as n-octyl-3-mercaptopropionate, and the like. The amount of the chain transfer agent added varies depending on the target molecular weight and molecular weight distribution, and is preferably within the range of 0.1 to 5.0 mass % relative to the amount of the polymerizable monomer added.

[0115] (Surfactant)

[0116] During the polymerization reaction, a surfactant is added from the viewpoint of preventing the agglomeration of the resin particles in the dispersion and maintaining a good dispersion state. Examples of surfactants include well-known surfactants such as cationic surfactants such as dodecyl ammonium bromide and dodecyl trimethyl ammonium bromide, anionic surfactants such as sodium stearate, sodium lauryl sulfate (sodium dodecyl sulfate), and sodium dodecylbenzene sulfonate, and nonionic surfactants such as dodecyl polyoxyethylene ether and hexadecyl polyoxyethylene ether. These surfactants can be used alone or in combination of two or more.

[0117] The dispersion treatment can be performed using mechanical energy such as a homogenizer, a shearing disperser, a friction disperser, a high-pressure jet disperser, an ultrasonic disperser, and a high-pressure impact disperser.

[0118] (Method for preparing colorant particle dispersion)

[0119] The colorant particle dispersion is prepared by dispersing the colorant in an aqueous medium. It should be noted that, when preparing the colorant particle dispersion, the surfactant may be added to improve the dispersion stability of the colorant particles. In addition, the mechanical energy may be used for dispersion treatment.

[0120] The volume-based median diameter of the colorant particles in the dispersion is preferably in the range of 10 to 300 nm, more preferably in the range of 100 to 200 nm, and even more preferably in the range of 100 to 150 nm. The volume-based median diameter of the colorant particles can be measured using an electrophoretic light scattering photometer (ELS-800; OTSUKA ELECTRONICS CO., LTD.).

[0121] (Method for preparing release agent particle dispersion)

[0122] When a release agent is used, the release agent is dispersed in an aqueous medium in the same manner as in the preparation method of the resin particle dispersion to prepare a release agent particle dispersion.

[0123] (Method for Forming Toner Particles)

[0124] After the prepared amorphous resin particle dispersion (crystalline resin particle dispersion) and colorant particle dispersion are mixed, the amorphous resin particles (crystalline resin particles) and the colorant particles are agglomerated in an aqueous medium. In addition, the mixed solution is heated to fuse the particles to form toner particles. When a release agent is used, the release agent particle dispersion is also mixed and agglomerated and fused together with the release agent particles. During agglomeration and fusion, a coagulant having a concentration above the critical fusion concentration is added, and the mixed solution is heated to a temperature above the glass transition temperature (Tg) of the amorphous resin, thereby promoting agglomeration and fusion.

[0125] (Coagulant)

[0126] The coagulant is not particularly limited, and includes metal salts such as alkali metal salts and alkaline earth metal salts. Examples of metal salts include monovalent metal salts such as sodium chloride, potassium chloride, and lithium chloride, divalent metal salts such as calcium chloride, magnesium chloride, copper sulfate, and magnesium sulfate, and trivalent metal salts such as iron and aluminum. As for the coagulant, a divalent metal salt is preferred from the viewpoint that the coagulant can be coagulated in a smaller amount.

[0127] In addition, in the case of the toner, the toner base particles may be aged as necessary. The obtained dispersion of the toner base particles is heated and aged until toner base particles having a target circularity are obtained.

[0128] (Shelling)

[0129] In the case of forming a toner matrix particle with a core-shell structure, the toner matrix particle is used as a core particle, and a shell layer is formed on the surface of the core particle. Specifically, a resin particle dispersion in which a resin constituting the shell layer is dispersed in an aqueous medium is prepared, and the dispersion is added to the toner matrix particle dispersion, and the resin particles of the shell layer are condensed and welded on the surface of the toner matrix particle. Thus, a dispersion of toner matrix particles having a core-shell structure can be obtained. In order to more firmly condense and weld the resin particles of the shell layer on the core particle, a heat treatment can be performed. The heat treatment is performed until the toner matrix particles with a target circularity are obtained.

[0130] (cool down)

[0131] The dispersion of the toner base particles is cooled. The cooling rate is preferably in the range of 1 to 20°C / min. The cooling method is not particularly limited, and cooling may be performed by introducing a refrigerant from the outside of the reaction container or by directly injecting cold water into the reaction system.

[0132] (Filter cleaning)

[0133] The dispersion of the cooled toner matrix particles is filtered to separate the toner particles into solid and liquid, and the obtained wet toner cake (collection of toner particles in the form of cake) is washed to remove the surfactant, agglomerating agent, etc. As a method for solid-liquid separation, centrifugal separation, vacuum filtration using a suction filter, etc., filtration using a filter press, etc. can be used. When washing, water can be used until the conductivity of the filtrate reaches 10 μS / cm, for example.

[0134] (dry)

[0135] The toner cake after filtering and washing is dried. For drying, a spray dryer, a vacuum freeze dryer, a reduced pressure dryer, a static shed dryer, a mobile shed dryer, a fluidized bed dryer, a rotary dryer, a stirring dryer, etc. can be used. The moisture content of the dried toner particles is preferably 5% by mass or less, and more preferably 2% by mass or less. In the case where the dried toner particles are agglomerated by the weak inter-particle attraction, the agglomerate can be pulverized. As a pulverization device, a jet mill, a HENSCHEL MIXERS, a coffee grinder, a food processor, etc. can be used.

[0136] (Addition of external additives)

[0137] When adding the external additive to the toner base particles, the external additive is added to the dried toner particles and mixed in. As a mixing device for the external additive, a Henschel mixer, a coffee grinder, or the like can be used.

[0138] The reason why the colorant of the present embodiment exerts the effect of the present invention is presumed as follows. Vaporization is suppressed by mixing the wax with a shorter chain length to be vaporized with the melted wax with a longer chain length. In the fixing means of the present embodiment, a heat source exists near the clamping portion, so less heat energy is lost during the fixing of the colorant image, and the melting rate of the colorant is faster. For an image forming device having such a fixing means, if there is a toner with a distribution ratio of a release agent with a shorter carbon chain length and a release agent with a longer carbon chain length, vaporization can be suppressed by entanglement of the wax with a shorter chain length with the melted wax with a longer chain length before vaporization. When the ratio is 2 or more, low-temperature fixability is easily exhibited, and when it is 6 or less, the wax to be vaporized and the wax with a longer chain length can be fully fused.

[0139] (Configuration of Image Forming Apparatus)

[0140] Next, an image forming apparatus including the fixing means in this embodiment will be described.

[0141] Figure 2 It is a cross-sectional view showing an example of the configuration of the image forming apparatus in this embodiment.

[0142] like Figure 2 As shown, in the image forming apparatus of this embodiment, a charging brush 111 as a charging means for uniformly charging the surface of the photosensitive drum 10 to a given potential and a cleaner 112 for removing the toner remaining on the photosensitive drum 10 are arranged around the photosensitive drum 10 that is driven to rotate. In addition, the image forming apparatus is provided with a laser scanning optical system 20 as an exposure means for scanning and exposing the photosensitive drum 10 charged by the charging brush 111 with a laser beam.

[0143] The laser scanning optical system 20 contains a laser diode, a polygon mirror, and an fθ optical element (all not shown). In the control unit, each print data of yellow, magenta, cyan, and black is transferred by the host. In addition, the laser scanning optical system 20 outputs the print data of each color in sequence as a laser beam, scans and exposes the photosensitive drum 10, and forms electrostatic latent images of each color in sequence on the photosensitive drum 10.

[0144] The developing cartridge 30 is a developing means for supplying toners of various colors to the photosensitive drum 10 on which the electrostatic latent image is formed, thereby developing the full-color image. The developing cartridge 30 is provided with four different color developing cartridges 31Y, 31M, 31C, and 31Bk containing toners of yellow, magenta, cyan, and black, around a support shaft 33. The developing cartridge 30 rotates around the support shaft 33, and each of the developing cartridges 31Y, 31M, 31C, and 31Bk is guided to a position facing the photosensitive drum 10.

[0145] In each of the developing cartridges 31Y, 31M, 31C, and 31Bk, a toner regulating member is pressed (contacted) against the outer circumferential surface of the developer carrier (developing roller) 25 that rotates to convey toner. The toner regulating member regulates the amount of toner conveyed by the developing roller 25 and charges the conveyed toner.

[0146] The developing cartridge 30 rotates around the support shaft 33 whenever an electrostatic latent image of each color is formed on the photosensitive drum 10 by the laser scanning optical system 20. The developing cartridges 31Y, 31M, 31C, and 31Bk containing toners of corresponding colors are sequentially introduced at positions facing the photosensitive drum 10. By making the developing rollers 25 in the developing cartridges 31Y, 31M, 31C, and 31Bk contact or non-contact the photosensitive drum 10, the charged toners of the respective colors are sequentially supplied to the photosensitive drum 10 on which the electrostatic latent images of the respective colors are sequentially formed, and development is performed.

[0147] In addition, at a position closer to the downstream side of the photosensitive drum 10 in the rotation direction than the developing box 30, an endless intermediate transfer belt 40 is arranged as an intermediate transfer body. The intermediate transfer belt 40 is rotated synchronously with the photosensitive drum 10. In addition, the intermediate transfer belt 40 is pressed by a rotatable primary transfer roller 41 and contacts the photosensitive drum 10. A rotatable secondary transfer roller 43 is arranged in the portion of the support roller 42 that supports the intermediate transfer belt 40. In the secondary transfer roller 43, a transfer material such as recording paper is pressed against the intermediate transfer belt 40.

[0148] Furthermore, in the space between the developing cartridge 30 and the intermediate transfer belt 40 , a cleaner 50 for scraping off the toner remaining on the intermediate transfer belt 40 is arranged so as to be contactable and separable from the intermediate transfer belt 40 .

[0149] The paper feeding means 60 guides the transfer material to the intermediate transfer belt 40. The paper feeding means 60 includes a paper feeding tray 61 for accommodating the transfer material, a paper feeding roller 62 for feeding the transfer material accommodated in the paper feeding tray 61 one by one, and a timing roller 63 for feeding the fed transfer material to between the intermediate transfer belt 40 and the secondary transfer roller 43 in synchronization with the image formed on the intermediate transfer belt 40. The paper feeding means 60 presses the transfer material fed between the intermediate transfer belt 40 and the secondary transfer roller 43 to the intermediate transfer belt 40 through the secondary transfer roller 43, and the toner image is transferred from the intermediate transfer belt 40 to the transfer material by pressure.

[0150] The transfer material to which the toner image is transferred by pressure is introduced to the fixing means 70 by the conveying means 66 constituted by a suction belt or the like. After the toner image is SURF-fixed by the fixing means 70 , the transfer material is discharged on the upper surface of the apparatus main body 100 through the vertical conveying path 80 .

[0151] Fixing means 70 can also be used Figure 3 The fixing means 70 is shown. Figure 3 It is a schematic diagram showing the structure of other fixing means.

[0152] The fixing means 70 includes a fixing belt 71 (annular belt), a heater 72 (heating component), and a pressure roller 73 (opposing component). The heater 72 is arranged on the inner circumferential surface side of the fixing belt 71 so as to heat the fixing belt 71 from the inner circumferential side. The pressure roller 73 (opposing component) is arranged on the outer circumferential surface side of the fixing belt 71 so as to be opposed to the heater 72 via the fixing belt 71. A clamping portion is formed between the outer circumferential surface of the fixing belt 71 and the pressure roller 73. With respect to the fixing means 70, the toner on the transfer material transported by the fixing belt 71 is fixed at the opposing position. In other words, with respect to the fixing means 70, when the transfer material passes through the clamping portion, heat and pressure are applied to the toner image so as to be fixed to the transfer material. That is, the fixing means in this embodiment is also referred to as a SURF fixing method.

[0153] Next, the operation of forming a full-color image using the image forming apparatus will be described in detail.

[0154] First, the photoreceptor drum 10 and the intermediate transfer belt 40 are driven to rotate at the same peripheral speed, and the photoreceptor drum 10 is charged to a predetermined potential by the charging brush 111 .

[0155] Next, the charged photosensitive drum 10 is exposed to a yellow image by the laser scanning optical system 20, and an electrostatic latent image of a yellow image is formed on the photosensitive drum 10. Next, charged yellow toner is supplied to the photosensitive drum 10 from the developing cartridge 31Y via the toner control member, and the yellow image is developed. Next, the intermediate transfer belt 40 is pressed by the primary transfer roller 41 against the photosensitive drum 10 on which the yellow toner image is formed, and the yellow toner image formed on the photosensitive drum 10 is transferred to the intermediate transfer belt 40 by the primary transfer roller 41.

[0156] Next, the developing cartridge 30 is rotated about the support shaft 33, and the developing cartridge 31M containing magenta toner is introduced at a position facing the photosensitive drum 10. As in the case of the yellow image, the magenta toner image is transferred from the photosensitive drum 10 to the intermediate transfer belt 40. The same procedure is followed for the cyan toner and the black toner, and the cyan toner and the black toner images are sequentially superimposed to form a full-color toner image.

[0157] Next, the transfer material is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43 , and the full-color toner image formed on the intermediate transfer belt 40 is secondarily transferred onto the transfer material.

[0158] Next, the transfer material is sent to the fixing means 70 , where the full-color toner image is fixed on the transfer material. Finally, the transfer material is discharged from the upper surface of the device main body 100 through the vertical conveying path 80 .

[0159] As mentioned above, although embodiment of this invention is specifically described, embodiment of this invention is not limited to the said example, Various changes can be added.

[0160] [Example]

[0161] <Polyester resin particle dispersion>

[0162] (Preparation of polyester resin 1)

[0163] In a four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, 285.7 parts by mass of a 2-mol addition product of bisphenol A propylene oxide, 66.9 parts by mass of terephthalic acid, 47.4 parts by mass of fumaric acid, and 1.43 parts by mass of an esterification catalyst (tin octylate) were added, and polycondensation reaction was carried out at 230° C. for 8 hours, and at 8 kPa for 1 hour, and then cooled to 160° C. Next, a mixture of 3.3 parts by mass of acrylic acid, 26.4 parts by mass of styrene, 6.6 parts by mass of butyl acrylate, and 5.3 parts by mass of a polymerization initiator (di-tert-butyl peroxide) was added dropwise through a dropping funnel over 1 hour. Next, after the addition polymerization reaction was continued for 1 hour while being maintained at 160° C., the temperature was raised to 200° C., and after being maintained at 10 kPa for 1 hour, styrene and butyl acrylate were removed to obtain a polyester resin 1 having a mixed structure.

[0164] (Preparation of polyester resins 2 to 7)

[0165] Polyester resins 2 to 7 were obtained in the same manner as in Polyester Resin 1 except that the components of the polyester resin particle dispersion were as shown in Table 1 below.

[0166] It should be noted that, for polyester resin 5, 285.7 parts by mass of bisphenol A propylene oxide 2 mol addition product, 66.9 parts by mass of terephthalic acid, 47.4 parts by mass of fumaric acid, and 1.43 parts by mass of an esterification catalyst (tin octylate) were added to a four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and a polycondensation reaction was carried out at 230° C. for 8 hours and at 8 kPa for 1 hour, and then cooled to 160° C.

[0167] The composition of each polyester resin is shown in Table 1.

[0168] [Table 1]

[0169] Table 1

[0170]

[0171] (Preparation of Polyester Resin Particle Dispersion 1)

[0172] 1200 parts by mass of polyester resin was dissolved in 200 parts by mass of ethyl acetate, and then mixed with an aqueous solution in which sodium polyoxyethylene lauryl ether sulfate was dissolved in 800 parts by mass of ion exchange water so as to have a concentration of 1% by mass, and dispersed using an ultrasonic homogenizer. The ethyl acetate was removed from the solution under reduced pressure, and the solid content concentration was adjusted to 20% by mass. Thus, a polyester resin microparticle dispersion 1 in which microparticles based on polyester resin 1 were dispersed in an aqueous medium was prepared.

[0173] (Preparation of Polyester Resin Particle Dispersions 2 to 7)

[0174] Polyester resin particle dispersions 2 to 7 were obtained in the same manner as in the preparation example of the polyester resin particle dispersion 1.

[0175] <Release Agent Microparticle Dispersion>

[0176] (Preparation of Release Agent Fine Particle Dispersion Liquid 1)

[0177] 200 parts by mass of paraffin wax (Paraffin Wax-155; SO-NIX Co., Ltd.) as a release agent was heated to 95°C and dissolved. Then, the paraffin wax was added to 800 parts by mass of a surfactant aqueous solution in which sodium alkyl diphenyl ether disulfonate was dissolved in ion exchange water to a concentration of 3% by mass, and then dispersed using an ultrasonic homogenizer. The solid content concentration was adjusted to 20% by mass. Thus, a release agent fine particle dispersion 1 in which release agent fine particles were dispersed in an aqueous medium was prepared.

[0178] The volume-based median diameter of the release agent fine particles was measured using a Microtrac particle size distribution analyzer (UPA-150; Nikkiso Co., Ltd.) and was 190 nm.

[0179] (Preparation of Release Agent Fine Particle Dispersions 2 to 5)

[0180] Mold release agent particle dispersions 2 to 5 were obtained in the same manner as the mold release agent particle dispersion 1 except that the components of the mold release agent particle dispersion were changed as shown in Table 2 below. Mold release agent particle dispersion 2 used paraffin wax (Paraffin Wax-130; SO-NIX Co., Ltd.), mold release agent particle dispersion 3 used microcrystalline wax (Hi-Mic-2065; NIPPON SEIRO Co., Ltd.), mold release agent particle dispersion 4 used FT wax (FNP-0090; NIPPON SEIRO Co., Ltd.), and mold release agent particle dispersion 5 used FT wax (FT-0070; NIPPON SEIRO Co., Ltd.).

[0181] The components of each release agent fine particle dispersion are shown in Table 2.

[0182] [Table 2]

[0183] Table 2

[0184] Release agent microparticle dispersion number Colorant Type 1 Paraffin Wax-155 2 Paraffin Wax-130 3 Hi-Mic-2065 4 FNP-0090 5 FT-0070

[0185] (Preparation of Colorant Microparticle Dispersion Liquid)

[0186] 50 parts by mass of copper phthalocyanine (CI Pigment Blue 15:3) was added to a surfactant aqueous solution in which sodium alkyl diphenyl ether disulfonate was dissolved in 200 parts by mass of ion exchange water to a concentration of 1% by mass, and then dispersed using an ultrasonic homogenizer. The solid content concentration was adjusted to 20% by mass. Thus, a colorant particle microdispersion liquid in which colorant particles composed of copper phthalocyanine were dispersed in an aqueous medium was prepared.

[0187] The volume-based median diameter of the colorant fine particles in the colorant fine particle dispersion was measured using a Microtrac particle size distribution analyzer (UPA-150; Nikkiso Co., Ltd.) and was 150 nm.

[0188] <Toner>

[0189] (Preparation of Toner 1)

[0190] 461.8 parts by mass of a dispersion liquid 1 of polyester resin particles, 7 parts by mass of a mold release agent dispersion liquid 1 as WAX A, 3 parts by mass of a mold release agent dispersion liquid 3 as WAX B, and 0.5 part by mass of an aqueous solution of sodium lauryl polyoxyethylene ether were put into a reaction vessel equipped with a stirrer, a condenser, and a thermometer. While stirring, 0.1N hydrochloric acid was added and the pH was adjusted to 2.5. Next, 0.4 part by mass of an aqueous solution of polyaluminum chloride (10% aqueous solution in terms of AlCl3) was added dropwise over 10 minutes, and then while stirring, the temperature was raised at a rate of 0.05 °C / min, and the particle size of the aggregated particles was appropriately measured using "MULTISIZER3" (manufactured by BECKMAN·COULTER). After the median particle size based on volume of the aggregated particles reached 5.0 μm, the temperature increase was stopped, and 222.2 parts by mass of the dispersion liquid 1 of polyester resin particles was added dropwise over 1 hour. Further, the internal temperature was raised to 85 °C, and using a flow particle image analyzer (FPIA-2000; manufactured by SYSMEX Corporation), it was cooled to room temperature at a rate of 10 °C / min at the time point when the average circularity became 0.960. After the reaction liquid was repeatedly filtered and washed, toner particles 1 were obtained by drying. To the obtained toner particles 1, 1% by mass of hydrophobic silica (number average primary particle size = 12 nm, degree of hydrophobization = 68) and 1% by mass of hydrophobic titanium oxide (number average primary particle size = 20 nm, degree of hydrophobization = 63) were added and mixed using "HENSCHEL MIXERS" (manufactured by Mitsui Miike Chemical Machinery Co., Ltd.). Then, coarse particles were removed by using a sieve with a pore size of 45 μm, and toner 1 was obtained. The median particle size based on volume in toner 1 was 5.6 μm, and the average circularity was 0.965.

[0191] (Preparation of Toners 2 to 19)

[0192] Except that WAX A and WAX B were as shown in Table 3, the same procedure as for toner 1 was carried out to obtain toners 2 to 19. The median particle size based on volume of the obtained toners 2 to 19 was 5.6 μm, and the average circularity was 0.965.

[0193] The components of each toner are shown in Table 3.

[0194] [Table 3]

[0195] Table 3

[0196]

[0197] <Calculation Method of A1 / B1>

[0198] As described above, in the range of 45 or more and 55 or less carbon atoms in the carbon atom distribution when the number of carbon atoms is set as the horizontal axis and the content is set as the vertical axis based on the results obtained by gas chromatography, the point at which the slope of the tangent line in the curve corresponding to the function representing the carbon atom distribution changes from positive to negative is set as the minimum value (A1), and the maximum value in the range of 45 or more and 55 or less carbon atoms is set as B1, and A1 / B1 is calculated.

[0199] <Calculation method of A2 / B2>

[0200] As described above, in the carbon atom distribution, the total value of the content in the range of 30 or more and less than 50 carbon atoms is set as A2, and the total value of the content in the range of 50 or more and 60 or less carbon atoms is set as B2, and A2 / B2 is calculated.

[0201] Tcp1, Tcp2, and the amount of styrene were calculated as described above.

[0202] [Table 4]

[0203] Table 4

[0204]

[0205] <Evaluation machine>

[0206] As the evaluation machine, a commercially available printer (MAGICOLOR (registered trademark) 2300DL: Konica Minolta, Inc.) using the electrophotographic method was used. The fixing means was equipped with Figure 3 the fixing means shown. It should be noted that the fixing means of the evaluation machine uses a fixing means adopting a heat roller fixing method with respect to the toner of Comparative Example 3.

[0207] <Evaluation of low-temperature fixability>

[0208] The above-described evaluation machine in which the surface temperatures of the upper fixing belt and the lower fixing roller were modified to be changeable was used. On CF paper (A4 80 g / m 2 ; Konica Minolta, Inc.), while changing the fixing temperature at intervals of 5 °C, the toner adhesion amount of 8 g / m 2Trials were conducted on the output of solid images at a fixing temperature of 180 °C and a fixing speed of 250 mm / sec until cold offset occurred. The lowest surface temperature of the upper fixing belt where cold offset did not occur was studied and evaluated as the lower limit fixing temperature for low-temperature fixability. In each trial, the fixing temperature refers to the surface temperature of the upper fixing belt, and the surface temperature of the fixed roller is usually set 20 °C lower than that of the upper fixing belt. A lower lower limit fixing temperature indicates better low-temperature fixability. In this evaluation, cases where the lower limit fixing temperature (Under offset (U.O.)) is below 145 °C (using the following evaluation criteria ◎, ○, △, △△) are considered qualified.

[0209] [Evaluation Criteria]

[0210] ◎: Below 130 °C

[0211] ○: 130 °C or above and below 135 °C

[0212] △: 135 °C or above and below 140 °C

[0213] △△: 140 °C or above and below 145 °C

[0214] ×: 145 °C or above

[0215] [Evaluation of Belt Durability]

[0216] At a fixing temperature of 180 °C, after outputting 100,000 sheets of text charts equivalent to a printing rate of 5%, the fixing temperature was cooled until it reached room temperature. Then, a paper passing durability test was conducted, and the test was interrupted when breakage, cracking, or breaking of the fixing belt occurred, and the cumulative number of passed sheets at that time was recorded. In this evaluation, cases where the cumulative number of passed sheets is 200,000 sheets or more (using the following evaluation criteria ◎, ○, △, △△) are considered qualified.

[0217] [Evaluation Criteria]

[0218] ◎: 500,000 sheets or more

[0219] ○: 400,000 sheets or more and below 500,000 sheets

[0220] △: 300,000 sheets or more and below 400,000 sheets

[0221] △△: 200,000 sheets or more and below 300,000 sheets

[0222] ×: 100,000 sheets or more and below 200,000 sheets

[0223] [Evaluation of UFP Number]

[0224] The same evaluation machine as that for the evaluation of low-temperature fixability was used. A particle counter (Particle Sizer FMPS3091; TOKYO DYLEC Co., Ltd.) was installed at the exhaust port of the image evaluation device body. The 3C image with a printing area of ​​20% of A4-sized paper was evaluated by the number of UFPs when 250 sheets were output at a fixing temperature of 180°C. In this evaluation, a UFP number of less than 10×10 5 The case where there were ◎, ○, △, △△ (based on the following evaluation criteria) was considered acceptable.

[0225] ◎: Less than 5×10 4 indivual

[0226] ○:5×10 4 More than and less than 1×10 5 indivual

[0227] △: 1×10 5 More than and less than 5×10 5 indivual

[0228] △△:5×10 5 More than 10 and less than 10×10 5 indivual

[0229] ×: 10×10 5 More than

[0230] The evaluation results are shown in Table 5.

[0231] [Table 5]

[0232] Table 5

[0233]

[0234] As shown in Table 5, when fixed by a given fixing means, toners 1 to 16 having A1 / B1 of 0.70 or less were good in low-temperature fixing property, belt durability, and UFP number. On the other hand, in toner 19 (Comparative Example 3) using a fixing means other than the given fixing means, low-temperature fixing property was insufficient. In addition, in toner 17 (Comparative Example 1) having A1 / B1 of not less than 0.70, low-temperature fixing property was also insufficient. In addition, in toner 18 (Comparative Example 2) having A1 / B1 of not less than 0.70 and A2 / B2 of not less than 2.0 and less than 6.0, belt durability and UFP number were insufficient.

[0235] (Effect)

[0236] As described above, in the image forming system of the present embodiment, when a fixing means of the SURF fixing method is used and the ratio of the minimum value A1 to the maximum value B1 in the range of carbon atom number greater than 45 and less than 55 in the carbon atom number distribution is less than 0.70, the low-temperature fixing property, belt durability and UFP number become good.

[0237] Industrial Applicability

[0238] The image forming system of the present invention provides an image forming system that excels in many characteristics required for image formation and forms a good image.

[0239] Explanation of symbols

[0240] 10 Photoreceptor drum

[0241] 20 Laser scanning optical system

[0242] 25 Development roller

[0243] 30, 31Bk, 31C, 31M, 31Y developer cartridges

[0244] 33 Axis

[0245] 40 Intermediate transfer belt

[0246] 41 1st transfer roller

[0247] 42 Support roller

[0248] 43 2nd transfer roller

[0249] 50 Cleaner

[0250] 60 Paper supply means

[0251] 61 Paper feed tray

[0252] 62 Paper feed roller

[0253] 63 Timing roller

[0254] 66 Transportation Method

[0255] 70 Fixing means

[0256] 71 Fusing belt

[0257] 72 Heater

[0258] 73 Pressure roller

[0259] 80 Vertical conveyor

[0260] 100 Device body

[0261] 111 with brush

[0262] 112 Cleaner

[0263] S Transfer material

Claims

1. An image forming system, which is an image forming system for forming an image by fixing a toner containing a release agent on a recording medium by a fixing means, wherein: The fixing means has: Annular belt; a heating member disposed on the inner circumferential surface side of the endless belt; and an opposing member disposed on the outer circumferential surface side of the endless belt so as to oppose the heating member via the endless belt, The fixing means fixes the toner on the recording medium conveyed by the endless belt at the opposed position. The release agent has a carbon number distribution with the carbon number as the horizontal axis and the content as the vertical axis based on the results obtained by gas chromatography. In the range of carbon number of 45 or more and 55 or less in the carbon number distribution, at least one minimum value of the content is included, When the smallest local value is defined as A1 and the maximum value in the range of 45 to 55 carbon atoms is defined as B1, A1 / B1 is 0.70 or less.

2. The image forming system according to claim 1, wherein: In the carbon atom number distribution, When the total value of the content in the range of 30 to 50 carbon atoms is defined as A2, and the total value of the content in the range of 50 to 60 carbon atoms is defined as B2, A2 / B2 is 2.0 or more and 6.0 or less.

3. The image forming system according to claim 1 or 2, wherein: In the carbon atom number distribution, There are one or more local maximum values ​​in the ranges of 44 or less carbon atoms and 56 or more carbon atoms.

4. The image forming system according to any one of claims 1 to 3, wherein: The toner comprises a polyester resin, The content of the styrene-based monomer in the toner is 0.2% by mass or more and 20% by mass or less.

5. The image forming system according to claim 4, wherein: The content of the styrene-based monomer in the toner is 0.5% by mass or more and 10% by mass or less.

6. The image forming system according to claim 4, wherein: When the toner is measured by differential scanning calorimetry, two local maximum values ​​exist between 60° C. or higher and 90° C. or lower.

7. The image forming system according to any one of claims 4 to 6, wherein: The polyester resin is styrene-modified polyester.

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