Developing device, process cartridge and electrophotographic image forming apparatus

Abstract

A developing device with high charging stability that uses toner with excellent low-temperature fixing properties. The developing device has a developing roller and a toner, and the toner has toner particles containing a crystalline material, and the resistivity of the toner at a frequency of 0.01 Hz obtained by AC impedance measurement is 2.00×10 14 Ω·m or less, the developing roller having a substrate with a conductive outer surface and a resin layer on the outer surface of the substrate, and a frequency obtained by AC impedance measurement of the developing roller is 1.0×10 2 Impedance Z in Hz is 1.00 x 10 4 Ω or more, and the frequency obtained by measuring the AC impedance of the developing roller is 1.0 × 10 2 Hz, the phase θ1 is −40° to −10°, and the frequency obtained by measuring the AC impedance of the developing roller is 1.0×10 4 The phase θ2 of Hz is −60° or less.

Description

[Technical Field]

[0001] The present disclosure relates to a developing device, a process cartridge, and an electrophotographic image forming apparatus. [Background technology]

[0002] Image forming apparatuses such as copiers and printers are required to be compact and easy to maintain, and from this viewpoint, a one-component development system is preferably used.

[0003] Furthermore, with environmental awareness on the rise these days, there is a greater demand for energy-saving products than ever before. To contribute to energy conservation through toner, studies have been underway to lower the fixing temperature of toner, and in particular, technological studies have been conducted that apply the sharp melting properties of crystalline materials and crystalline resins. For example, Patent Document 1 proposes a toner containing a large amount of crystalline resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2017 / 0131653 [Patent Document 2] Japanese Patent Publication No. 2022-080159 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-206777 Summary of the Invention [Problem to be solved by the invention]

[0005] Toners containing a large amount of crystalline resin have a low fixing temperature, but the large amount of crystalline material causes the toner to have low resistance, which can result in the toner not being able to obtain a sufficient charge amount, resulting in problems such as image fogging.

[0006] Here, a method for ensuring that the toner has a sufficient charge amount is disclosed, for example, in Patent Document 2. Furthermore, a method for improving image fogging caused by a low charge amount of the toner is disclosed, for example, in Patent Document 3.

[0007] However, according to the inventors' investigations, in Patent Document 2, the resistance design of the developing roller is insufficient, which can cause toner on the developing roller to leak through the developing roller when passing through the nip of the regulating member on the developing roller, resulting in problems such as fogging and toner scattering.

[0008] In addition, in Patent Document 3, the resistance value of the developing roller is increased to maintain the charge of the toner on the developing roller. However, simply increasing the resistance value can lead to significant charge-up on the surface of the developing roller during continuous printing, which can cause the toner to adhere too strongly to the developing roller. As a result, when high-density image printing is performed continuously, problems such as low image density can occur.

[0009] As described above, there is still room for further study regarding the charge stabilization in a developing device of a toner containing a large amount of crystalline material and having excellent low-temperature fixing properties. The present disclosure provides a developing device with high charging stability that uses a toner with excellent low-temperature fixability. [Means for solving the problem]

[0010] The present disclosure provides a development device having a development roller and toner, the toner has toner particles containing a crystalline material; The resistivity of the toner at a frequency of 0.01 Hz obtained by AC impedance measurement is 2. 00×10 14 Ω·m or less, the developing roller has a substrate having a conductive outer surface and a resin layer on the outer surface of the substrate, The frequency obtained by measuring the AC impedance of the developing roller is 1.0 x 10 2 Impedance Z in Hz is 1.00 x 104 is greater than or equal to Ω, The frequency obtained by measuring the AC impedance of the developing roller is 1.0 x 10 2 The phase θ1 of Hz is -40° to -10°, The frequency obtained by measuring the AC impedance of the developing roller is 1.0 x 10 4 The phase θ2 of the Hz is −60° or less.

[0011] The present disclosure relates to a process cartridge configured to be detachably attached to a main body of an electrophotographic image forming apparatus, The present invention relates to a process cartridge comprising the above-mentioned developing device.

[0012] The present disclosure relates to an electrophotographic image forming apparatus, The present invention relates to an electrophotographic image forming apparatus comprising the above-mentioned developing device. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to provide a developing device with high charging stability that uses a toner with excellent low-temperature fixability. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of a developing roller. [Figure 2] FIG. 10 is a schematic cross-sectional view showing another example of the developing roller. [Figure 3] FIG. 2 is a schematic diagram of a process cartridge. [Figure 4] FIG. 1 is a schematic diagram of an electrophotographic image forming apparatus. [Figure 5] FIG. 10 is a schematic diagram showing a state in which a measurement electrode is formed on a developing roller. [Figure 6] FIG. 2 is a cross-sectional view of a developing roller and a measurement electrode. [Figure 7] FIG. 1 is a schematic diagram of an impedance measurement system. [Figure 8] FIG. 1 is a schematic diagram showing an example of an apparatus for measuring the surface potential of a developing roller. [Figure 9] FIG. 10 is a schematic diagram of a circuit for measuring leakage current flowing from the toner to the developing roller. [Figure 10] FIG. 1 is a schematic diagram of an electrophotographic image forming apparatus for image evaluation. DETAILED DESCRIPTION OF THE INVENTION

[0015] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints, unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. Note that when XX is a group, multiple XXs may be selected, and the same applies to YY and ZZ.

[0016] A "monomer unit" refers to the reacted form of a monomer substance in a polymer. For example, one section of carbon-carbon bond in the main chain of a polymer formed by polymerizing a vinyl monomer is considered to be one unit. A vinyl monomer can be represented by the following formula (6): [ka]

[0017] In formula (6), R A represents a hydrogen atom or an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group), and R B represents an optional substituent. In addition, in the present disclosure, a crystalline resin refers to a resin that shows a clear endothermic peak in differential scanning calorimetry (DSC) measurement.

[0018] To satisfy the low-temperature fixing property, the resistivity of the toner obtained by the AC impedance measurement method of the toner described later must be 2.00 x 1014 The resistivity of the toner must be Ω·m or less. As mentioned above, crystalline materials have lower electrical resistance than amorphous materials due to their regular arrangement. If the resistivity of the toner is 2.00×10 14 If the resistivity exceeds Ω·m, the crystalline material in the toner is insufficient, and good low-temperature fixability cannot be achieved. The resistance value of the above toner is 1.00 x 10 12 ~2.00×10 14 Ω m is preferred, and 1.00×10 13 ~6.00×10 13 It is more preferable that the resistance is Ω·m. The resistance of the toner can be controlled by the amount of crystalline material and the dispersion state of the crystalline material. It can also be controlled by the resistance of the external additive and the amount of external additive coated on the toner surface.

[0019] On the other hand, 2.0 × 10 14 Toner with a low resistivity of Ω·m or less does not easily retain charge. As a result of extensive research by the present inventors, in order to retain the charge of toner that does not easily retain charge, it was found that the toner has a low resistivity of Ω·m or less and a high resistivity of Ω·m or less. 4 We found that it is important that the phase θ2 of the Hz is -60° or less. By keeping the phase θ2 below -60°, it is possible to suppress the leakage of charge between the toner and the developing roller, thereby improving image fogging.

[0020] The phase of each frequency obtained by AC impedance measurement method represents the insulating and conducting characteristics of the object being measured at that frequency. The phase represents the deviation of the output current waveform from the input current waveform, with a phase of -90° indicating the behavior of a capacitor, a phase of 0° indicating the behavior of a resistor, and a phase of +90° indicating the behavior of an inductor. The phase between 0° and -90° indicates an equivalent circuit that includes elements of a resistor and a capacitor. In a typical single-component development system, the voltage ON-OFF cycle is 1.0 x 10 4 The time around Hz corresponds to the time during which the toner on the developing roller is rubbed when passing through the regulating member.

[0021] Therefore, the frequency of the developing roller is 1.0 x 10 4 The more the electrical characteristics at Hz behave like a capacitor, the less likely the charge on the toner surface to leak to the developing roller. When the phase θ2 range exceeds -60°, the resistance-like behavior becomes stronger, the developing roller becomes more likely to leak charge, and the toner charge, which was previously difficult to retain, easily leaks to the developing roller, causing image fogging.

[0022] From the viewpoint of further suppressing image fogging, the value of the phase θ2 is preferably equal to or less than −70°, and the phase θ2 is preferably −90 to −60°, more preferably −85 to −70°, and further preferably −82 to −75°. The value of the phase θ2 can be increased by, for example, increasing the amount of conductive fine particles added, and can be decreased by, for example, decreasing the amount of conductive fine particles added or using an ionic conductive agent.

[0023] In addition, to prevent charging of the developing roller due to continuous printing, the frequency obtained by measuring the AC impedance of the developing roller is 1.0 x 10 2 It is necessary that the phase θ1 of the frequency band is between -40° and -10°. In the present disclosure, it is important to control the phase θ1 within the range of -40° to -10° while keeping the phase θ2 within the above range. The more resistance-like the behavior on the low frequency side, the more charge accumulation in the developing roller can be alleviated, thereby suppressing charge-up of the developing roller due to continuous printing. As a result, it is possible to improve the reduction in image density caused by insufficient toner development amount on the photosensitive member.

[0024] In addition, the frequency is 1.0 × 10 2 The reason for using Hz is that it corresponds to the time it takes for the toner carried on the developing roller to pass through the regulating blade portion, and therefore corresponds to the ON-OFF time of the circuit. From the viewpoint of improving image density, the phase θ1 is preferably −37° to −13°, more preferably −32° to −20°, and even more preferably −32° to −25°.

[0025] The value of the phase θ1 can be increased, for example, by controlling the dispersibility of the conductive fine particles. The value of the phase θ1 can also be decreased, for example, by reducing the amount of conductive fine particles added or by using ionic conductive particles instead of conductive fine particles. By setting Rc, σc / Rc, d, and σd / d within the preferred ranges described below, the phase θ1 can be easily controlled within the above range.

[0026] While satisfying the above two conditions, the frequency is 1.0 × 10 2 The value of impedance Z in Hz is 1.00 x 10 4 Ω or more is necessary to realize the characteristics due to the phases θ1 and θ2. The higher the value of the impedance Z, the better. There is no particular upper limit, but for example, 1.00×10 8 Ω or less. The impedance Z is, for example, 1.00×10 4 ~1.00×10 8 Ω, preferably 1.00×10 5 ~5.00×10 7 Ω, and more preferably 5.00×10 5 ~1.00×10 7 It is Ω. The impedance Z can be controlled by, for example, conductive fine particles in the resin layer, as will be described in detail later.

[0027] As described above, by using a toner with low resistivity and a high content of crystalline material and by setting the phase θ1, phase θ2, and impedance Z within specific ranges, it is possible to obtain a developing device that suppresses image fogging and image density reduction and has high charging stability. The present disclosure will be further described below.

[0028] <Toner> The toner has an endothermic heat quantity obtained by differential scanning calorimetry, which will be explained in the measurement method section, of, for example, 18 to 70 J / g, preferably 20 to 70 J / g, in terms of improving low-temperature fixability, hot offset, and heat-resistant storage stability. The endothermic heat quantity is more preferably 20 to 40 J / g. The endothermic heat quantity of the toner can be controlled by adjusting the amount of crystalline material added and the compatibility of the crystalline material with the resin.

[0029] In order to efficiently plasticize the binder resin during fixing, it is preferable that the melting temperature of the crystalline material is low. Therefore, the endothermic peak temperature obtained by differential scanning calorimetry of the toner is preferably 40 to 75°C, and more preferably 60 to 75°C. The endothermic peak temperature can be controlled by the melting point of the crystalline material.

[0030] Furthermore, the more the toner melts and exerts its effect, the better the low-temperature fixability can be. Therefore, the endothermic heat amount at 30 to 80°C obtained by differential scanning calorimetry of the toner is preferably 20 to 70 J / g, more preferably 22 to 50 J / g. The endothermic heat amount at 30 to 80°C depends on the melting point of the crystalline material and the annealing treatment conditions for growing the crystals of the crystalline material. You can have more control.

[0031] Such a crystalline material is preferably used in combination with an amorphous resin. Therefore, from the viewpoint of compatibility with the amorphous resin when melted, the crystalline material preferably contains at least one selected from the group consisting of a crystalline resin and an ester wax.

[0032] It is preferable that the amorphous resin and the crystalline material form a sea-island structure in the cross section of the toner. When an ester wax is used as the crystalline material, the effect of plasticizing the amorphous resin can be enhanced by increasing the contact area between the ester wax and the amorphous resin, so it is preferable that the ester wax forms a sea-island structure in which it is dispersed in the form of islands in the cross section of the toner, as described below. The islands in this sea-island structure should preferably be as small as possible.

[0033] That is, it is preferable that the crystalline material contains an ester wax, and the toner particles further contain an amorphous resin. When a cross section of the toner is observed with a scanning transmission electron microscope, it is preferable that the amorphous resin and the ester wax form a sea-island structure in the cross section of the toner. For example, the sea-island structure is such that the amorphous resin forms a continuous sea in the cross section of the toner, and the crystalline material (e.g., ester wax) is dispersed in the amorphous resin to form islands.

[0034] When a crystalline resin is used as the crystalline material, the crystalline resin preferably contains a monomer unit represented by the following formula (1). The toner particles preferably further contain an amorphous resin. A crystalline resin containing a monomer unit represented by formula (1) is likely to phase separate from the amorphous resin when the crystalline material crystallizes and is likely to be compatible with the amorphous resin when melted, and is therefore preferred from the viewpoints of low-temperature fixability and hot offset resistance. [ka] In formula (1), R 4 represents a hydrogen atom or a methyl group, and n represents an integer of 15 to 35.

[0035] An example of a method for introducing the monomer unit represented by formula (1) into a crystalline resin is a method of polymerizing the following (meth)acrylic acid esters: stearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, heneicosanyl (meth)acrylate, behenyl (meth)acrylate, lignoceryl (meth)acrylate, ceryl (meth)acrylate, octadecyl (meth)acrylate, and myricyl (meth)acrylate.

[0036] The crystalline resin may have only one type of monomer unit represented by formula (1), or may have two or more types. The content of the unit in the crystalline resin is preferably 40.0% by mass to 90.0% by mass, more preferably 45.0% by mass to 85.0% by mass, and even more preferably 50.0% by mass to 80.0% by mass. Within this range, a better balance between low-temperature fixability and hot offset resistance is achieved.

[0037] The crystalline resin may have, in addition to the monomer unit represented by formula (1), another monomer unit other than the monomer unit represented by formula (1). A method for introducing another monomer unit into the crystalline resin includes, for example, polymerizing the above-mentioned (meth)acrylic acid ester with another vinyl monomer.

[0038] Examples of other vinyl monomers include the following: (meth)acrylic acid esters such as styrene, α-methylstyrene, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0039] Monomer having a urea group: for example, a monomer obtained by reacting an amine having 3 to 22 carbon atoms [primary amine (normal butylamine, t-butylamine, propylamine, isopropylamine, etc.), secondary amine (di-normal ethylamine, di-normal propylamine, di-normal butylamine, etc.), aniline, cycloxylamine, etc.] with an isocyanate having 2 to 30 carbon atoms and an ethylenically unsaturated bond by a known method, etc.

[0040] Monomers having a carboxy group; for example, methacrylic acid, acrylic acid, and 2-carboxyethyl (meth)acrylate. Monomers having a hydroxy group; for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc. Monomers having an amide group: for example, acrylamide, a monomer obtained by reacting an amine having 1 to 30 carbon atoms with a carboxylic acid having 2 to 30 carbon atoms and an ethylenically unsaturated bond (acrylic acid, methacrylic acid, etc.) by a known method. Monomer with lactam structure; N-vinyl-2-pyrrolidone.

[0041] Among these, a monomer having a lactam structure is preferred, and N-vinyl-2-pyrrolidone is more preferred. By containing a monomer unit having a lactam structure, the affinity between the crystalline resin and paper is improved, and the abrasion resistance of the fixed image is easily improved. That is, the crystalline resin preferably contains a monomer unit having a lactam structure, and more preferably contains a monomer unit having a five-membered ring lactam structure.

[0042] The monomer unit having a lactam structure is preferably represented by the following formula (L) (more preferably formula (L-1)). [ka] In formulas (L) and (L-1), R2 represents a hydrogen atom or a methyl group, and n is an integer of 1 to 4 (preferably 1 to 3).

[0043] The content of monomer units having a lactam structure in the crystalline resin is 2.0%. It is preferable that the content is 15.0 mass % or more and 15.0 mass % or less.

[0044] The crystalline resin can be synthesized by copolymerizing a (meth)acrylic acid ester for introducing the unit with another vinyl monomer, followed by further reaction with another vinyl monomer via a hydrogen abstraction reaction. The hydrogen abstraction reaction is a reaction in which a hydrogen atom bonded to a carbon atom is abstracted to generate a radical, and the generated radical can then be reacted with another vinyl monomer. This allows the units in the crystalline vinyl resin to form a more aggregated state within the molecule, making it easier to increase crystallinity.

[0045] The content of the crystalline material in the toner particles is, for example, 15 to 55% by mass, preferably 20 to 50% by mass, and more preferably 22 to 45% by mass. The content of the crystalline resin in the toner particles is, for example, 15 to 50% by mass, preferably 20 to 45% by mass, and more preferably 30 to 40% by mass. The content of the ester wax in the toner particles is, for example, 5 to 35% by mass, and preferably 5 to 30% by mass.

[0046] In toners containing a large amount of any of the above-described crystalline materials, the increase in the amount of crystalline material in the toner may cause a percolation phenomenon within the toner, resulting in a decrease in resistance. As an approach to increasing the resistance from the toner side, when the cross section of the toner is observed using a scanning transmission electron microscope, the area ratio of the crystalline material in the cross section of the toner is, for example, 34% or less, preferably 30% or less. The area ratio is, for example, 10 to 34%, preferably 10 to 30%, and more preferably 20 to 30%.

[0047] Each component constituting the toner and the method for producing the toner will be described in more detail below. <Binder resin> The toner particles may contain a binder resin, and the above-mentioned crystalline resin and / or amorphous resin may be the binder resin. Examples of binder resins include polyester resins, vinyl resins, and other binder resins such as the following resins or polymers: styrene acrylic resins, polyester resins, epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and mixed or composite resins thereof.

[0048] The binder resin is preferably a polyester resin, a styrene-acrylic resin, or a hybrid resin thereof, more preferably a styrene-acrylic resin, because these resins are inexpensive, easily available, and have excellent low-temperature fixing properties. The amorphous resin is preferably a styrene-acrylic resin.

[0049] The polyester resin can be obtained by selecting and combining suitable compounds from polycarboxylic acids, polyols, hydroxycarboxylic acids, etc., and synthesizing them using a conventionally known method such as transesterification or polycondensation.

[0050] Polycarboxylic acids are compounds containing two or more carboxy groups in one molecule, and among these, dicarboxylic acids are compounds containing two carboxy groups in one molecule and are preferably used.

[0051] Examples of dicarboxylic acids include oxalic acid, succinic acid, glutaric acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-carboxylic acid, hexacarboxylic acid, Examples include hydroterephthalic acid, malonic acid, pimelic acid, suberic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediacetic acid, o-phenylenediacetic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, and cyclohexanedicarboxylic acid.

[0052] Examples of polycarboxylic acids other than dicarboxylic acids include trimellitic acid, trimesic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, pyrenetetracarboxylic acid, itaconic acid, glutaconic acid, n-dodecylsuccinic acid, n-dodecenylsuccinic acid, isododecylsuccinic acid, isododecenylsuccinic acid, n-octylsuccinic acid, n-octenylsuccinic acid, etc. These may be used alone or in combination of two or more.

[0053] Polyols are compounds containing two or more hydroxyl groups in one molecule, and among these, diols are compounds containing two hydroxyl groups in one molecule and are preferably used.

[0054] Specifically, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene 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, 1,14-eicosanedecanediol, diethylene glycol, Examples of the alkylene oxide include triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-butenediol, neopentyl glycol, 1,4-cyclohexanediol, polytetramethylene glycol, hydrogenated bisphenol A, bisphenol A, bisphenol F, bisphenol S, and alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts of the above bisphenols.

[0055] Among these, alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols are preferred, and alkylene oxide adducts of bisphenols and their combined use with alkylene glycols having 2 to 12 carbon atoms are particularly preferred.

[0056] Examples of trivalent or higher polyols include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine, sorbitol, trisphenol PA, phenol novolac, cresol novolac, and alkylene oxide adducts of the above trivalent or higher polyphenols. These may be used alone or in combination of two or more. The polyester resin may also be a polyester resin containing a urea group. It is preferable that the carboxyl groups of the polyester resin, such as terminal groups, are not capped.

[0057] Examples of the styrene-acrylic resin include homopolymers made of the following polymerizable monomers, copolymers obtained by combining two or more of these, and mixtures thereof.

[0058] Styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methyl styrene-based monomers such as p-butylstyrene, p-methylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-hexylstyrene, p-octylstyrene, p-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene and p-phenylstyrene; (meth)acrylic monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, dimethyl phosphate ethyl (meth)acrylate, diethyl phosphate ethyl (meth)acrylate, dibutyl phosphate ethyl (meth)acrylate, and 2-benzoyloxyethyl (meth)acrylate, (meth)acrylonitrile, 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid, and maleic acid; Vinyl ether monomers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketone monomers such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; Polyolefins such as ethylene, propylene, and butadiene.

[0059] The styrene-acrylic resin may contain a polyfunctional polymerizable monomer, if necessary. Examples of the polyfunctional polymerizable monomer include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2'-bis(4-((meth)acryloxydiethoxy)phenyl)propane, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.

[0060] In order to control the degree of polymerization, it is also possible to further add a known chain transfer agent and polymerization inhibitor.

[0061] Examples of the polymerization initiator for obtaining the styrene-acrylic resin include organic peroxide-based initiators and azo-based polymerization initiators. Examples of organic peroxide initiators include benzoyl peroxide, lauroyl peroxide, di-α-cumyl peroxide, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, bis(4-t-butylcyclohexyl)peroxydicarbonate, 1,1-bis(t-butylperoxy)cyclododecane, t-butylperoxymaleic acid, bis(t-butylperoxy)isophthalate, methyl ethyl ketone peroxide, tert-butylperoxy-2-ethylhexanoate, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and tert-butylperoxypivalate.

[0062] Examples of the azo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobismethylbutyronitrile, and 2,2'-azobis-(methyl isobutyrate).

[0063] Furthermore, a redox initiator, which is a combination of an oxidizing substance and a reducing substance, can also be used as the polymerization initiator. The oxidizing substances include inorganic peroxides such as hydrogen peroxide, persulfates (sodium, potassium and ammonium salts) and oxidizing metal salts such as tetravalent cerium salts.

[0064] Examples of reducing substances include reducing metal salts (divalent iron salts, monovalent copper salts, and trivalent chromium salts), ammonia, lower amines (amines having approximately 1 to 6 carbon atoms, such as methylamine and ethylamine), amino compounds such as hydroxylamine, reducing sulfur compounds such as sodium thiosulfate, sodium hydrosulfite, sodium hydrogensulfite, sodium sulfite, and sodium formaldehyde sulfoxylate, lower alcohols (having 1 to 6 carbon atoms), ascorbic acid or a salt thereof, and lower aldehydes (having 1 to 6 carbon atoms).

[0065] The polymerization initiator is selected based on its 10-hour half-life temperature and is used alone or in combination. The amount of polymerization initiator added varies depending on the desired degree of polymerization, but is generally 0.5 to 20.0 parts by mass per 100.0 parts by mass of polymerizable monomer.

[0066] <Crystalline materials> As a crystalline material for improving the sharp melting property of the toner, in addition to the crystalline resin having the monomer unit represented by formula (1) and ester wax, a crystalline polyester resin can also be used. The ester wax is not particularly limited, and known ester waxes used in toners such as those listed below can be used.

[0067] Esters of monohydric alcohols and fatty carboxylic acids, or esters of monohydric carboxylic acids and fatty alcohols, such as behenyl behenate, stearyl stearate, behenyl stearate, and palmityl palmitate; esters of dihydric alcohols and fatty carboxylic acids, or esters of dihydric carboxylic acids and fatty alcohols, such as ethylene glycol distearate, dibehenyl sebacate, and hexanediol dibehenate; esters of trihydric alcohols and fatty carboxylic acids, or esters of trihydric carboxylic acids and fatty alcohols, such as glycerin tribehenate; pentaerythritol tetate Esters of tetrahydric alcohols and aliphatic carboxylic acids, such as distearate and pentaerythritol tetrapalmitate, or esters of tetrahydric carboxylic acids and aliphatic alcohols; esters of hexahydric alcohols and aliphatic carboxylic acids, such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate, or esters of hexahydric carboxylic acids and aliphatic alcohols; esters of polyhydric alcohols and aliphatic carboxylic acids, such as polyglycerol behenate, or esters of polyhydric carboxylic acids and aliphatic alcohols; and natural ester waxes, such as carnauba wax and rice wax. These may be used alone or in combination. Among these, ethylene glycol distearate, behenyl stearate, and dipentaerythritol hexastearate are preferred.

[0068] As the crystalline polyester resin, for example, a condensation product of an aliphatic diol and an aliphatic dicarboxylic acid can be used.

[0069] <Crosslinking agent> In order to control the molecular weight of the binder resin constituting the toner particles, a crosslinking agent may be added during polymerization of the polymerizable monomer. For example, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, Ethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, divinylbenzene, bis(4-acryloxypolyethoxyphenyl)propane, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol #200, #400, #600 diacrylates, dipropylene glycol diacrylate, polypropylene glycol diacrylate, polyester diacrylate (MANDA Nippon Kayaku), and those in which the above acrylates have been replaced with methacrylates.

[0070] The amount of the crosslinking agent added is preferably 0.001 parts by mass or more and 15,000 parts by mass or less relative to 100 parts by mass of the polymerizable monomer.

[0071] <Release agent> The toner may contain a known wax as a release agent. Specific examples include petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum and their derivatives, montan wax and its derivatives, hydrocarbon waxes produced by the Fischer-Tropsch process and their derivatives, polyolefin waxes such as polyethylene and polypropylene and their derivatives, and natural waxes such as carnauba wax and candelilla wax and their derivatives. Derivatives also include oxides, block copolymers with vinyl monomers, and graft-modified products.

[0072] Other examples include alcohols such as higher aliphatic alcohols, fatty acids such as stearic acid and palmitic acid or their acid amides, esters, and ketones, hydrogenated castor oil and its derivatives, vegetable waxes, and animal waxes.These may be used alone or in combination.

[0073] Among these, polyolefin, hydrocarbon wax produced by the Fischer-Tropsch method, or petroleum wax is preferably used, as it tends to improve the developability and transferability. Note that these waxes may contain an antioxidant to the extent that it does not affect the properties of the toner. The content of the release agent is preferably 1.0 part by mass or more and 30.0 parts by mass or less relative to 100.0 parts by mass of the binder resin. The content of the release agent in the toner particles may be, for example, 1 to 30% by mass, or 2 to 15% by mass.

[0074] The melting point of the release agent is preferably 30° C. or higher and 120° C. or lower, and more preferably 60° C. or higher and 100° C. or lower. By using a release agent with a melting point of 30° C. or higher and 120° C. or lower, the release effect is efficiently exerted and a wider fixing area is ensured.

[0075] <Coloring agent> The toner particles may contain a colorant. Known pigments and dyes can be used as the colorant. Pigments are preferred as the colorant because they have excellent weather resistance. Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and basic dye lake compounds. Specific examples include: CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62 and 66.

[0076] Magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzyl compounds, and the like. Examples include imidazolone compounds, thioindigo compounds, and perylene compounds. Specific examples include CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221 and 254, and CI Pigment Violet 19.

[0077] Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specific examples include the following: CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185, 191 and 194.

[0078] Examples of black colorants include those toned to black using the above yellow, magenta, and cyan colorants, as well as carbon black. These colorants can be used alone or in mixture, or further in the state of a solid solution. The colorant is preferably used in an amount of 1.0 part by mass or more and 20.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0079] <Charge control agents and charge control resins> The toner particles may contain a charge control agent or a charge control resin. Known charge control agents can be used, and charge control agents that have a high triboelectric charging speed and can stably maintain a constant triboelectric charge amount are particularly preferred. Furthermore, when the toner particles are produced by a suspension polymerization method, charge control agents that have low polymerization inhibition properties and are substantially free of solubilized substances in aqueous media are particularly preferred.

[0080] Examples of substances that control the toner to be negatively charged include monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic and dicarboxylic acid-based metal compounds, aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid-based compounds, metal-containing naphthoic acid-based compounds, boron compounds, quaternary ammonium salts, calixarene, and charge control resins.

[0081] Examples of the charge control resin include polymers or copolymers having sulfonic acid groups, sulfonate salt groups, or sulfonate ester groups. As the polymer having sulfonic acid groups, sulfonate salt groups, or sulfonate ester groups, a polymer containing 2% by mass or more, more preferably 5% by mass or more, of a sulfonate group-containing acrylamide monomer or a sulfonate group-containing methacrylamide monomer in copolymerization ratio is preferred.

[0082] The charge control resin preferably has a glass transition temperature (Tg) of 35°C or higher and 90°C or lower, a peak molecular weight (Mp) of 10,000 or higher and 30,000 or lower, and a weight average molecular weight (Mw) of 25,000 or higher and 50,000 or lower. When used, it can impart desirable triboelectric charging properties without affecting the thermal properties required of the toner particles. Furthermore, when the charge control resin contains sulfonic acid groups, the dispersibility of the charge control resin itself and the dispersibility of colorants, etc., in the polymerizable monomer composition is improved, thereby further improving coloring power, transparency, and triboelectric charging properties.

[0083] These charge control agents or charge control resins may be added singly or in combination of two or more kinds. The amount of the charge control agent or charge control resin added is preferably 0.01 to 20.0 parts by mass, more preferably 0.5 to 10.0 parts by mass, relative to 100.0 parts by mass of the binder resin.

[0084] <External additives> The toner may contain an external additive. For example, in order to improve the fluidity, chargeability, cleaning properties, etc., a fluidizing agent, a charging aid, a cleaning aid, etc. may be added to the toner particles to obtain the toner.

[0085] Examples of external additives include inorganic oxide fine particles such as silica fine particles and alumina fine particles, positively charged particles such as hydrotalcite and melamine resin, and inorganic stearic acid compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles. These may be used alone or in combination of two or more. The external additive preferably contains inorganic oxide fine particles. The content of the external additive is, for example, 0.1 to 5.0 parts by mass, and preferably 0.5 to 3.0 parts by mass, relative to 100 parts by mass of the toner particles.

[0086] <Method of manufacturing toner particles> The toner particles preferably have core particles containing a binder resin (e.g., an amorphous resin) and a shell on the surface of the core particles. The method for producing the toner particles is not particularly limited, and known means can be used, such as a kneading and pulverization method or a wet production method. Examples of wet production methods include a suspension polymerization method, a solution suspension method, an emulsion polymerization aggregation method, and an emulsion aggregation method. From the viewpoints of achieving uniform particle size, shape controllability, and ease of obtaining toner particles with a core-shell structure, a wet production method is preferred, and among these, a suspension polymerization method and an emulsion aggregation method are preferred. The suspension polymerization method will be described below as an example.

[0087] <Suspension polymerization method> In the suspension polymerization method, first, a polymerizable monomer for producing a binder resin, a colorant, and other additives as needed are uniformly dissolved or dispersed using a disperser such as a ball mill or an ultrasonic disperser to prepare a polymerizable monomer composition (polymerizable monomer composition preparation step). At this time, a multifunctional monomer, a chain transfer agent, a wax as a mold release agent, a charge control agent, a plasticizer, and the like can be appropriately added as needed.

[0088] Next, the polymerizable monomer composition is poured into a previously prepared aqueous medium, and droplets of the polymerizable monomer composition are formed into the desired toner particle size using a stirrer or disperser with high shear force (granulation process).

[0089] It is preferable that the aqueous medium used in the granulation process contains a dispersion stabilizer in order to control the particle size of the toner particles, sharpen the particle size distribution, and prevent the coalescence of toner particles during the manufacturing process. Dispersion stabilizers are generally broadly classified into polymers that exhibit repulsive forces due to steric hindrance and poorly water-soluble inorganic compounds that stabilize dispersion by electrostatic repulsive forces. Fine particles of poorly water-soluble inorganic compounds are preferably used because they dissolve in acid or alkali and can be easily removed by washing with acid or alkali after polymerization.

[0090] As the dispersion stabilizer of the poorly water-soluble inorganic compound, one containing any of magnesium, calcium, barium, zinc, aluminum, and phosphorus is preferably used. More preferably, one containing any of magnesium, calcium, aluminum, and phosphorus is desired. Specific examples include the following.

[0091] Magnesium phosphate, tricalcium phosphate, aluminum phosphate, zinc phosphate, magnesium carbonate, calcium carbonate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide Sodium, calcium metasilicate, calcium sulfate, barium sulfate, hydroxyapatide.

[0092] The dispersion stabilizer may be used in combination with an organic compound such as polyvinyl alcohol, gelatin, methyl cellulose, methylhydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, or starch. These dispersion stabilizers are preferably used in an amount of 0.01 to 2.00 parts by mass per 100 parts by mass of the polymerizable monomer.

[0093] Furthermore, to refine the dispersion stabilizer, a surfactant may be used in an amount of 0.001 to 0.1 parts by mass per 100 parts by mass of the polymerizable monomer. Specifically, commercially available nonionic, anionic, and cationic surfactants can be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, and calcium oleate are preferably used.

[0094] After the granulation step, or while the granulation step is being carried out, the temperature is preferably set to 50°C or higher and 90°C or lower to polymerize the polymerizable monomers contained in the polymerizable monomer composition, thereby obtaining a toner particle dispersion (polymerization step).

[0095] In the polymerization step, it is preferable to perform stirring so as to achieve a uniform temperature distribution in the vessel. When adding a polymerization initiator, it can be added at any timing and for any required time. The temperature may be raised in the latter half of the polymerization reaction in order to obtain a desired molecular weight distribution. Furthermore, in order to remove unreacted polymerizable monomers, by-products, etc. from the system, a portion of the aqueous medium may be distilled off in the latter half of the reaction or after completion of the reaction. The distillation operation may be performed under normal pressure or reduced pressure.

[0096] In the suspension polymerization method, an oil-soluble initiator is generally used as the polymerization initiator, and a water-soluble initiator may be used in combination with the oil-soluble initiator, if necessary. These polymerization initiators can be used alone or in combination, and a chain transfer agent, a polymerization inhibitor, etc. can also be added to control the degree of polymerization of the polymerizable monomer.

[0097] After the polymerization step, a cooling step is preferably carried out in which the temperature of the obtained toner particle dispersion is cooled to a temperature lower than the crystallization temperature or glass transition temperature of the binder resin by controlling the cooling rate. The cooling rate is, for example, 1 to 300°C / sec, preferably 2 to 200°C / sec, and more preferably 5 to 100°C / sec. The cooling step solidifies the binder resin before crystal growth of the crystalline material, thereby enabling the crystal nuclei of the crystalline material to be dispersed in the binder resin.

[0098] After cooling, an annealing step may be carried out. The annealing temperature is preferably 45°C to 65°C. The annealing time is preferably 1 to 15 hours, and more preferably 2 to 12 hours. The annealing step allows crystal growth of the crystalline material that is compatible with the binder resin, starting from the crystal nuclei.

[0099] The particle size of the toner particles is preferably a weight average particle size of 3.0 μm or more and 10.0 μm or less, from the viewpoint of obtaining high-definition, high-resolution images. The volume average particle size of the toner can be measured by the pore electrical resistance method. For example, it can be measured using a Coulter Counter Multisizer 3 (manufactured by Beckman Coulter, Inc.). The toner particle dispersion thus obtained is sent to a filtration process for solid-liquid separation of the toner particles and the aqueous medium.

[0100] The solid-liquid separation for obtaining toner particles from the obtained toner particle dispersion can be carried out by a general filtration method. Then, in order to remove any foreign matter that has not been completely removed from the surface of the toner particles, It is preferable to further wash the toner by reslurrying or by washing with washing water. After sufficient washing, solid-liquid separation is again performed to obtain a toner cake. Thereafter, the toner cake is dried by a known drying means, and if necessary, particle groups having particle sizes other than the specified particle size are separated by classification to obtain toner particles. The particle groups having particle sizes other than the specified particle size separated at this time may be reused to improve the final yield.

[0101] <Toner manufacturing method> The mixer for externally adding the external additive to the toner particles is not particularly limited, and any known mixer, whether dry or wet, can be used. Examples include FM Mixer (manufactured by Nippon Coke & Engineering Co., Ltd.), Super Mixer (manufactured by Kawata Corporation), Nobilta (manufactured by Hosokawa Micron Corporation), and Hybridizer (manufactured by Nara Kikai Co., Ltd.). To control the coating state of the external additive, the toner can be prepared by adjusting the rotation speed, processing time, and water temperature and amount in the jacket of the external addition device.

[0102] In addition, examples of sieving devices used to sift out coarse particles after external addition include Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonaseave, Gyrosifter (Tokuju Kogyo Co., Ltd.); Vibrasonic System (manufactured by Dalton Co., Ltd.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); Turbo Screener (manufactured by Turbo Kogyo Co., Ltd.); and Microsifter (manufactured by Makino Sangyo Co., Ltd.).

[0103] <Developing roller> A developing roller according to at least one aspect of the present disclosure has a conductive substrate and a resin layer on the outer peripheral surface of the substrate. An example of a developing roller is shown in Fig. 1. The developing roller 10 shown in Fig. 1 has a resin layer 12 laminated on the outer peripheral surface of a columnar or hollow cylindrical substrate 11. The layer configuration of the developing roller is not limited to the form shown in Fig. 1. As another form of the developing roller, as shown in Fig. 2, an elastic layer 13 may be provided between a base 11 and a resin layer 12 provided on the outer peripheral surface thereof.

[0104] When the outer surface of the developing roller is charged with a corona discharger and the potential of the outer surface is measured 0.06 seconds after the end of charging, the maximum value of the potential is preferably less than 20.0 V. The surface potential of the electrophotographic roller indicates the residual charge on the surface of the electrophotographic roller. If the potential is less than 20.0 V, the toner can be appropriately charged, which is preferable in terms of image fogging, and the toner can be prevented from sticking to the developing roller, which is preferable in terms of preventing a decrease in image density. The maximum value of the potential is preferably 15.0 V or less, and more preferably 10.0 V or less. The lower the maximum value of the outer surface potential, the better, and there is no particular lower limit. A preferred range for the maximum potential of the outer surface is, for example, 0 V or more and less than 20.0 V, particularly 0 V or more and 15.0 V or less, and further preferably 0 V or more and 10.0 V or less.

[0105] The impedance characteristics of the developing roller are 1.0×10 -1 Hz to 1.0 x 10 6 It is preferable that the number of elementary processes obtained from AC impedance measurements up to 100 Hz is one. By using one elementary process, charge-up of the developing roller can be further suppressed. In order to control the above physical properties, the following resin layer materials, conductive fine particle materials, and additives may be used to improve the dispersibility of the conductive fine particles. Specifically, methods for unifying the elementary processes include using conductive materials with similar conductive properties in combination, or combining conductive means such as ionic conductivity and electronic conductivity into one.

[0106] [Base] The substrate has a conductive outer surface and functions as a support member for the developing roller and, in some cases, as an electrode. Specific examples of the substrate preferably have a solid columnar or hollow cylindrical shape.

[0107] The material for the substrate can be appropriately selected from those known in the field of electroconductive members for electrophotography and materials usable for such developing rollers, and examples thereof include metals or alloys such as aluminum and stainless steel, carbon steel alloys, conductive synthetic resins, iron, and copper alloys.

[0108] Furthermore, the material constituting the substrate may be subjected to an oxidation treatment or a plating treatment with chromium, nickel, or the like. Either electroplating or electroless plating can be used as the type of plating. Electroless plating is preferred from the viewpoint of dimensional stability. Examples of electroless plating that can be used here include nickel plating, copper plating, gold plating, and various other alloy platings. The plating thickness is preferably 0.05 μm or more, and considering the balance between work efficiency and rust prevention ability, the plating thickness is preferably 0.1 to 30 μm.

[0109] A primer may be applied to the surface of the substrate to improve adhesion between the substrate and the resin layer. A known primer can be selected and used depending on the rubber material for forming the conductive layer and the material of the support. Examples of primer materials include thermosetting resins and thermoplastic resins, and specific examples of materials that can be used include phenolic resins, polyurethanes, acrylic resins, polyester resins, polyether resins, and epoxy resins.

[0110] [Resin layer] The developing roller has a resin layer on the outer surface of the substrate. For example, the resin layer is present on the outer surface of the developing roller. The resin layer may contain a binder resin. As the binder resin of the resin layer in the developing roller, polyurethane is preferably used to suppress charge leakage from the toner to the developing roller. The polyurethane preferably has at least one selected from the group consisting of a polyether structure and a polycarbonate structure, and more preferably has a polycarbonate structure. That is, the resin layer preferably contains polyurethane, and more preferably contains polyurethane having a polycarbonate structure. The polycarbonate structure provides high surface strength and good electrical resistance, making it easier to maintain the properties of the developing roller throughout its durability.

[0111] The structure of the polymer contained in the resin layer of the developing roller can be confirmed by, for example, pyrolysis GC / MS, FT-IR, or NMR analysis.

[0112] Polyurethane can be produced using (A) a polyol compound and (B) a polyisocyanate compound. Polyurethane is usually synthesized by the following methods (1) and (2). (1) A one-shot method in which a polyol component and a polyisocyanate component are mixed and reacted. (2) A method in which an isocyanate-terminated prepolymer obtained by reacting a portion of a polyol with an isocyanate is reacted with a chain extender such as a low-molecular-weight diol or low-molecular-weight triol.

[0113] In the present disclosure, polyurethane may be synthesized by any of the above methods, but a method of subjecting a hydroxyl-terminated prepolymer obtained by reacting a raw material polyol with an isocyanate to a thermal curing reaction with an isocyanate-terminated prepolymer obtained by reacting a raw material polyol with an isocyanate is more preferred.

[0114] Polyurethane contains hydroxyl-terminated prepolymer and isocyanate-terminated prepolymer. The polyurethane is preferably a reaction product of a mixture containing a hydroxyl-terminated prepolymer, an isocyanate-terminated prepolymer, a conductive filler, and an additive. The mixture can be used as a coating liquid for forming a resin layer. The polyurethane is more preferably a reaction product of a mixture containing a hydroxyl-terminated prepolymer, an isocyanate-terminated prepolymer, a conductive filler, and an additive.

[0115] When the polyurethane contains a large number of hydroxyl groups, isocyanate groups, or urea bonds, allophanate bonds, isocyanurate bonds, etc., the amount of polar functional groups present in the polyurethane increases, which can increase the water absorption of the polymer and reduce the volume resistivity of the resin layer. On the other hand, by thermally curing the hydroxyl-terminated prepolymer and the isocyanate-terminated prepolymer, a polyurethane with less unreacted polyol and polar functional groups can be obtained without using an excessive amount of isocyanate. This is therefore preferable from the viewpoint of further suppressing charge leakage from the toner to the developing roller.

[0116] (A) Polyol compound The polyol compound may be any polyol known for or usable in the synthesis of urethane resins. Examples of polyol compounds include polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols such as polybutadiene polyols and polyisoprene polyols, so-called polymer polyols obtained by polymerizing ethylenically unsaturated monomers in polyols, and polyester-polycarbonate copolymer polyols.

[0117] Among these, the polyol compound is preferably at least one selected from the group consisting of polycarbonate polyols and polyester polycarbonate copolymer polyols.

[0118] Examples of polycarbonate polyols include polynonamethylene carbonate diol, poly(2-methyl-octamethylene) carbonate diol, polyhexamethylene carbonate diol, polypentamethylene carbonate diol, poly(3-methylpentamethylene) carbonate diol, polytetramethylene carbonate diol, polytrimethylene carbonate diol, poly(1,4-cyclohexanedimethylene carbonate) diol, poly(2-ethyl-2-butyl-trimethylene) carbonate diol, and random / block copolymers thereof.

[0119] Examples of polyester polycarbonate copolymer polyols include the following: copolymers obtained by polycondensing the above-mentioned polycarbonate polyols with lactones such as ε-caprolactone, and copolymers of polyesters obtained by polycondensing diols such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentanediol, and neopentyl glycol with dicarboxylic acids such as adipic acid and sebacic acid.

[0120] (B) Polyisocyanate compound The polyisocyanate may be selected from commonly used and known polyisocyanates, such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, hydrogenated MDI, polymeric MDI, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). Among these, aromatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, and polymeric MDI are more preferably used. Other polyisocyanates may also be used as long as they do not affect the impedance value and surface potential.

[0121] The ratio of the number of isocyanate groups to the number of hydroxyl groups (hereinafter also referred to as "NCO / OH ratio") is preferably 1.0 to 2.0. If this NCO / OH ratio is 1.0 to 2.0, the crosslinking reaction proceeds, and the bleeding of unreacted components and low-molecular-weight polyurethane, known as "bleeding," is suppressed. The NCO / OH ratio is more preferably 1.0 to 1.6. If this NCO / OH ratio is 1.0 to 1.6, bleeding is suppressed and the hardness of the polymer can be reduced.

[0122] The content of polyurethane in the resin layer is not particularly limited, but is preferably 50 to 95% by mass, more preferably 60 to 80% by mass, and even more preferably 65 to 75% by mass.

[0123] (Conductive filler) The resin layer preferably contains a conductive filler to obtain conductivity. It is more preferable to use an electronic conductive agent as the conductive filler in the resin layer. The electronic conductive agent is preferably a conductive particle that exhibits electronic conductivity and has a surface functional group that can interact with a functional group present in the additive described below. Examples of electronic conductive agents that exhibit these properties include at least one selected from the group consisting of carbon black such as furnace black, thermal black, acetylene black, and ketjen black; metal oxide-based conductive particles such as titanium oxide whose surfaces have been treated with acidic functional groups; and metal-based conductive particles such as aluminum and iron whose surfaces have been treated with acidic functional groups.

[0124] The resin layer preferably contains conductive fine particles as the conductive filler. The conductive fine particles are preferably at least one selected from the group consisting of carbon black, indium-tin oxide, and antimony-titanium oxide. The conductive fine particles more preferably include carbon black. Furthermore, to achieve the desired impedance value and surface potential, the number-average diameter of the primary particles is 30 nm or less, which allows for high dispersion in the resin layer. Carbon black, which is likely to form a structure, is particularly preferably one with a DBP absorption of 90 ml / 100 g or less and a pH of 4.0 or less.

[0125] When the number average diameter of the primary particles of the conductive fine particles is 30 nm or less, conductive paths due to chains of conductive fine particles are unlikely to be formed, making it easier to obtain a sufficiently high impedance Z. The primary particle diameter of the conductive fine particles can be calculated using a transmission electron microscope (TEM). The lower the number average diameter, the better, and there is no particular lower limit. For example, the number average diameter of the primary particles of the conductive fine particles is, for example, 5 to 55 nm, preferably 5 to 30 nm, and more preferably 20 to 28 nm.

[0126] However, even if the number-average diameter of the primary particles of carbon black, DBP absorption, and pH are within the above ranges, when polycarbonate urethane is used as the binder resin, the carbon black may not be sufficiently dispersed, making it impossible to obtain the desired impedance.The reason why carbon black, which has the desired raw material properties, cannot be dispersed when polycarbonate urethane is used as the binder resin is not clearly understood, but it is speculated as follows.

[0127] The hydroxyl groups, which are surface functional groups of carbon black, tend to interact with the terminal hydroxyl groups of polycarbonate diol. On the other hand, the structure of the carbonate bond and hydrocarbon group bonded between the two hydroxyl groups of polycarbonate diol is hydrophobic due to the presence of the hydrocarbon group, making it less likely to interact with carbon black. Since the structure is more stable when hydrophobic and hydrophilic materials are close together, hydrophilic carbon black will be found in the vicinity of hydrophilic carbon black. As a result, carbon black tends to aggregate and become difficult to disperse.

[0128] In order to sufficiently disperse carbon black having the number average diameter of primary particles, DBP absorption amount, and pH within the above-mentioned ranges when using polycarbonate urethane as a binder resin, it is more preferable to add the additives described below.

[0129] In designing the developing roller to have a desired impedance Z, the resistance of the conductive fine particles is preferably 1 Ω·m or more and 1000 Ω·m or less, and more preferably 1 Ω·m or more and 10 Ω·m or less.

[0130] The content of the conductive fine particles is preferably added so as to achieve the desired impedance Z, and is preferably 30 parts by mass or less relative to 100 parts by mass of the polyurethane forming the resin layer, more preferably 10 to 30 parts by mass, and even more preferably 15 to 25 parts by mass.

[0131] When the content is 30 parts by mass or less, the distance between the conductive fine particles in the coating liquid is maintained at an appropriate level, the probability of collisions between the conductive fine particles due to Brownian motion, etc. is reduced, and the conductive fine particles are less likely to aggregate. This makes the conductive fine particles more easily dispersible and improves dispersion stability. As a result, the conductive fine particles are well dispersed in the resin layer formed by coating the coating liquid.

[0132] In order to achieve the above-mentioned specific impedance and surface potential, it is preferable to control the dispersion of the conductive fine particles. As for the dispersed particle size of the conductive fine particles, the arithmetic mean value Rc of the equivalent circle diameter of the conductive fine particles in the resin layer is preferably 60 nm or less. Furthermore, when the standard deviation of the equivalent circle diameter is σc [nm], it is more preferable that σc / Rc is 0.00 to 0.65.

[0133] The distance between the conductive particles is, for example, 60 to 150 nm, preferably 80 to 150 nm, and when the standard deviation of the distance between the wall surfaces is σd [nm], σd / d is, for example, 0.00 to 0.65, more preferably 0.00 to 0.60.

[0134] The reason why high impedance and low surface potential are more easily achieved when the equivalent circle diameter and wall-to-wall distance are within the above-mentioned ranges is presumed to be as follows. When the dispersed particle size is large, there are areas where the wall distance is close, making it easier for conductive paths to form, resulting in lower impedance Z and surface potential. On the other hand, when the dispersed particle size is small, the wall distance becomes more uniform, making it harder for conductive paths to form and increasing resistance, resulting in higher impedance Z. With regard to surface potential, localized charge accumulation is less likely to occur, making it possible to lower the surface potential. It should be noted that multiple types of conductive particles may be used in combination as long as they do not affect the impedance Z and the surface potential.

[0135] The arithmetic mean value Rc of the equivalent circle diameter is, for example, 40 to 102 nm, preferably 40 to 60 nm, and more preferably 50 to 60 nm. σc / Rc is, for example, 0.50 to 0.80, preferably 0.50 to 0.65, and more preferably 0.55 to 0.65.

[0136] The arithmetic mean value Rc and standard deviation σc of the equivalent circle diameter can be changed, for example, by the dispersion state in a mill when preparing the coating liquid for forming the resin layer. Weaker dispersion tends to increase Rc and σc, while stronger dispersion tends to decrease Rc and σc. Normally, Rc converges, so once a certain dispersion state is exceeded, σc can be reduced while Rc remains almost constant, and σc / Rc can be reduced.

[0137] The arithmetic mean value d of the distance between the wall surfaces is more preferably 90 to 120 nm, and even more preferably 95 to 115 nm. σd / d is more preferably 0.50 to 0.60, and even more preferably 0.54 to 0.59.

[0138] The arithmetic mean value d and standard deviation σd of the wall-to-wall distance can be changed, for example, by the dispersion state in a mill or the like when preparing the resin layer-forming coating liquid. Weaker dispersion tends to make d smaller and σd larger, while stronger dispersion tends to make d larger and σd smaller. Therefore, weaker dispersion tends to make σd / d larger, and stronger dispersion tends to make σd / d smaller.

[0139] (additives) One preferred embodiment involves the use of an additive to further improve the dispersibility of carbon black in a binder resin using polycarbonate urethane. Here, for example, at least one compound selected from the group consisting of a compound having a structure represented by the following formula (2), a compound having a structure represented by the following formula (3), and a compound having a structure represented by the following formula (4) can be suitably used as the additive. One method for incorporating the additive into the surface layer is to incorporate a dispersant into a coating liquid for forming a surface layer. Note that in a surface layer formed using a coating liquid for forming a surface layer containing at least one compound selected from the group consisting of a compound having a structure represented by formula (2) and a compound having a structure represented by formula (3), the compound may be incorporated at the end of the polyurethane polymer chain. Even in such cases, the effect of improving the dispersibility of carbon black can be expected; however, it is preferable that the additive be present in the surface layer independently of the polyurethane.

[0140] Among the compounds having the structures represented by formulas (2) to (4), the compound having the structure represented by formula (2) is more preferably used because it has particularly excellent dispersibility of carbon black and affinity with polycarbonate urethane. [ka]

[0141] In structural formula (2), R51 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms (preferably 3 to 12). t and u represent the average number of moles added, and each independently represents a number of 1 or more (preferably 5 to 30, more preferably 10 to 25). In the structural formula (3), R61 represents a monovalent hydrocarbon group having 1 to 8 carbon atoms (preferably 1 to 4 carbon atoms). v and w are the average number of moles added, and each independently represents a number of 1 or more (preferably 1 to 30, more preferably 5 to 30). In structural formula (4), R71 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms. x represents the average number of moles added and is a number of 1 or more (preferably 1 to 30, more preferably 4 to 15).

[0142] Formula (2) is polyoxyethylene polyoxypropylene alkyl ether, a polyether monool with a block-type addition polymerization structure of ethylene oxide and propylene oxide. The terminal hydroxyl groups of this polyether monool interact with the surface functional groups of the conductive filler carbon black through hydrogen bonding, acting as a dispersant for the carbon black. Furthermore, to enhance its effectiveness as a dispersant for carbon black, the structure is also compatible with polycarbonate urethane.

[0143] Ethylene oxide is introduced into the structure to ensure uniform distribution of the additive in the polycarbonate urethane. This is thought to be because the ethylene group in ethylene oxide is compatible with the hydrophobic hydrocarbon group in the polycarbonate urethane. Propylene oxide is introduced into the structure to improve the dispersibility of the conductive filler dispersed in the resin layer. This is thought to be because the side-chain methyl group of propylene oxide interacts with the conductive filler, improving the dispersibility of the conductive filler.

[0144] R51, a monovalent hydrocarbon group having 1 to 12 carbon atoms, is introduced into the structure to allow the additive to be distributed uniformly throughout the polycarbonate urethane. Being a monovalent hydrocarbon group improves compatibility with the hydrophobic hydrocarbon groups in the polycarbonate urethane, allowing the additive to be distributed uniformly throughout the polycarbonate urethane. Having 12 or fewer carbon atoms reduces steric hindrance with the polycarbonate urethane, making it easier for the additive to be distributed uniformly. Furthermore, since the compound of formula (2) has a mono-ol structure, it is less reactive than a diol and is less likely to be incorporated into the urethane reaction caused by the reaction of isocyanate with a polyol, which makes it less likely to lead to a decrease in the resistance of the polyurethane due to the introduction of an ether structure into the polycarbonate urethane.

[0145] The polyoxyethylene polyoxypropylene alkyl ether can be a commercially available product or can be obtained by synthesis. The synthesis of polyoxyethylene polyoxypropylene alkyl ether can be carried out by carrying out the following step (A) followed by step (B). Note that step (B) may also be carried out on a commercially available product whose structure has already been completed up to step (A).

[0146] Step (A): Reaction of alcohol with ethylene oxide Step (B): Reaction of the product obtained in step (A) with propylene oxide In step (A), the reaction can be carried out by adding ethylene oxide to an alcohol in the presence of a catalyst at 50 to 200°C, more preferably 100 to 160°C. Since ethylene oxide has a boiling point of 10.7°C and is in a gaseous state at this temperature, the reaction is preferably carried out in a pressurized environment in a sealed container. The pressure is preferably 0.1 MPa to 1.0 MPa. The reaction time is not particularly limited, but is preferably about 1 to 3 hours in order to reduce the amount of unreacted ethylene oxide.

[0147] The catalyst may be an acid catalyst or an alkali catalyst, but an alkali catalyst is preferred to facilitate purification after the reaction. Examples of alkali catalysts include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide, ammonium hydroxide, and tertiary amines. In view of the ease and efficiency of the reaction, sodium hydroxide and potassium hydroxide are particularly preferred. Examples of acid catalysts include Bronsted acids such as sulfuric acid and phosphoric acid, and Lewis acids such as stannic chloride and boron trifluoride.

[0148] The amount of catalyst used is preferably 0.1 to 5 mol % per 1 mol of alcohol in the case of sodium hydroxide or potassium hydroxide. Since ethylene oxide reacts with water to produce ethylene glycol, it is important to prevent water from entering the reaction system as much as possible, and a dehydration treatment may be carried out before the reaction in step (A) as necessary.

[0149] Step (B) can be carried out under the same conditions as step (A). Propylene oxide has a boiling point of 34.2°C and is in a gaseous state at reaction temperatures of 50 to 200°C, so the reaction is preferably carried out in a pressurized environment in a sealed container. The catalyst used in step (A) may be used as is, or a new catalyst may be added. When a new catalyst is added, the catalyst used in step (A) is preferred.

[0150] Formula (3) is a polyetheramine (monoamine) with a block-type addition polymerization structure of ethylene oxide and propylene oxide. The amino groups at the terminals of this polyetheramine interact with the surface functional groups of the conductive filler carbon black through hydrogen bonding, acting as a dispersant for the carbon black. Furthermore, to enhance its effectiveness as a dispersant, R61, a monovalent hydrocarbon group with 1 to 8 carbon atoms, is introduced, resulting in a structure that is highly compatible with the hydrophobic functional groups of polycarbonate urethane, resulting in a structure that is also highly compatible with polycarbonate urethane.

[0151] The polyether monoamine can be a commercially available product or can be obtained by synthesis. The synthesis of the polyether monoamine can be carried out by carrying out the following step (C) followed by step (D).

[0152] Step (C): Oxidation reaction of the compound of structural formula (2), which is a secondary alcohol Step (D): Reductive amination of the product obtained in step (C) Step (C) is the oxidation of a secondary alcohol to produce a ketone. The synthesis of ketones by oxidation of a secondary alcohol can be carried out using heavy metal salts such as chromic acid or manganese dioxide or their derivatives, or by non-heavy metal salt oxidation using dimethyl sulfoxide (DMSO) or hypohalous acids such as hypochlorous acid.

[0153] Although either method can be used for synthesis, oxidation reactions using hypohalous acids such as dimethyl sulfoxide (DMSO) or hypochlorous acid are preferred due to the environmental impact of heavy metals. Furthermore, dimethyl sulfoxide (DMSO) can undergo explosive reactions at room temperature depending on the electrophilic activating reagent used, requiring temperatures as low as -60°C, making the method using hypohalous acids more preferable. Examples of hypohalous acids include hypochlorites such as sodium hypochlorite and calcium hypochlorite (bleaching powder). Ketones can be obtained by reacting these hypochlorites with secondary alcohols in acetic acid.

[0154] When using dimethyl sulfoxide (DMSO), an electrophilic activating reagent is required. The electrophilic activating reagent increases the electrophilicity of the sulfur in DMSO, allowing it to undergo nucleophilic attack by the alcohol's hydroxyl group. This nucleophilic attack generates a dimethylalkoxysulfonium salt, which decomposes to yield a ketone and dimethyl sulfide. Examples of electrophilic activating reagents include dicyclohexylcarbodiimide (DCC), acetic anhydride, phosphorus pentoxide, sulfur trisulfide-pyridine complex, trifluoroacetic anhydride, oxalyl chloride, and halogens.

[0155] Step (D) is a reductive amination reaction that converts a ketone to an amine. The reaction is divided into two steps. First, a carbonyl group reacts with an amine to generate an iminium cation. Next, a hydride reducing agent attacks the iminium cation with a nucleophilic reaction, producing the amine. An iminium cation is produced. A borohydride reagent is preferably used as the reducing agent. Examples of borohydride reagents include sodium cyanoborohydride, sodium triacetoxyborohydride, and 2-picoline borane. Among these, sodium triacetoxyborohydride and 2-picoline borane are preferred due to their low toxicity. In the reductive amination reaction using a borohydride reagent, if the reagent has a bulky structure, steric hindrance makes it difficult to produce an iminium cation. Therefore, R61 in structural formula (3) is preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms.

[0156] Formula (4) is polyoxyethylene alkyl ether acetic acid. The terminal carboxylic acid in formula (4) interacts with the surface functional groups of the conductive filler carbon black through hydrogen bonding, acting as a dispersant for the carbon black. In addition, to enhance its effectiveness as a dispersant, R71, a monovalent hydrocarbon group with 1 to 12 carbon atoms, is introduced, resulting in a structure that is easily compatible with the hydrophobic functional groups of polycarbonate urethane, resulting in a structure that is also compatible with polycarbonate urethane.

[0157] Polyoxyethylene alkyl ether acetic acid can be obtained by synthesis or commercially available products. Polyoxyethylene alkyl ether acetic acid can be synthesized by carrying out the following step (E) followed by step (F). Note that step (F) may also be carried out on a commercially available product whose structure has been completed up to step (E). Step (E): Reaction of alcohol with ethylene oxide Step (F): Oxidation reaction of the primary alcohol, which is the product of step (E) Step (E) is the same as step (A) and can be prepared by the same method as step (A).

[0158] Step (F) is the oxidation of a primary alcohol to produce a carboxylic acid. Because the oxidation of a primary alcohol produces an aldehyde, followed by further oxidation to produce a carboxylic acid, it is necessary to select a reaction method and conditions that do not stop at the aldehyde. Methods for obtaining a carboxylic acid by oxidation of a primary alcohol include oxidation with an oxidizing agent and catalytic dehydrogenation using a catalyst. Oxidizing agents include permanganate, chromic acid, ruthenium tetroxide, and hypochlorite. Dehydrogenation catalysts include palladium, platinum, iridium, rhodium, and manganese.

[0159] The compounds represented by formulas (2) to (4) function as dispersants for conductive microparticles and have high affinity with polycarbonate urethane. Surfactants are typically used to improve the dispersibility and dispersion stability of conductive microparticles. However, the compounds represented by formulas (2) to (4) have a small number of functional groups that act on the surface functional groups of the conductive microparticles, so their surfactant effect is weak and they are not commonly used. Coupling agents and nonionic surfactants are commonly used as dispersants for microparticles.

[0160] Silane coupling agents, titanate coupling agents, and aluminum coupling agents are used as coupling agents, while polyester and polyether-based nonionic surfactants are used. However, adding these dispersants to polycarbonate urethane to a level that sufficiently enhances the dispersibility of carbon black (50 to 100% by mass relative to the carbon black) inhibits the conductivity of the carbon black and binder resin. Conversely, adding them in an amount that does not inhibit the conductivity of the carbon black and binder resin (10 to 40% by mass relative to the carbon black) does not result in sufficient dispersibility of the carbon black.

[0161] The amount of the compound represented by formulas (2) to (4) added is preferably 3.0 to 7.0 mass %, more preferably 3.0 to 5.0 mass %, based on the solid content in the coating material for forming the surface layer. %. The total content is preferably 18.9 to 46.0 parts by mass relative to 100 parts by mass of carbon black in the coating material for forming the surface layer. By ensuring that the content of the additive in the coating material for forming the surface layer is within the above range, the dispersibility of the conductive fine particles in the polyurethane is further improved, and the desired impedance value and surface potential can be more easily achieved.

[0162] The presence of additives in the resin layer can be confirmed and quantitatively evaluated by the following method. The resin layer of the developing roller is cut out, and the cut piece is subjected to, for example, 1 H-NMR, 13 Analysis is performed using CNMR, XPS, and FT-IR. This allows the carbonate structure of the binder resin, and the ether structure, amine structure, and carboxylic acid structure of the additives to be detected in the resin layer, and the ratio can be calculated from the peak ratios, etc.

[0163] Alternatively, sections can be extracted by immersing them overnight in an organic solvent such as 2-butanone (methyl ethyl ketone; MEK), and the extract and the extracted sections can be analyzed. 1 H-NMR, 13 Analysis using C-NMR, XPS, and FT-IR allows us to calculate the proportion of additives that were incorporated into the resin during the polymerization reaction and those that were not.

[0164] [Roughening particles] The resin layer may contain roughening particles. The roughening particles may be, for example, spherical particles. The particle diameter of the roughening particles is, for example, preferably in the range of 1 μm to 150 μm, and more preferably in the range of 5 μm to 30 μm. For example, at least one spherical particle selected from the following particles may be used. Urethane resin particles, acrylic resin particles, phenolic resin particles, silicone resin particles, polyacrylonitrile resin particles, polystyrene resin particles, polyurethane resin particles, nylon resin particles, polyethylene resin particles, polypropylene resin particles, preferably urethane resin particles. The content of the roughening particles in the resin layer is preferably 1 to 20% by mass, more preferably 5 to 15% by mass.

[0165] The developing roller may have an elastic layer on the outer surface of the substrate. The developing roller has the elastic layer between the substrate and the resin layer, for example. The elastic layer is not particularly limited, and any known elastic layer for developing rollers may be used. For example, a cured product of an addition-curing liquid silicone rubber mixture may be used.

[0166] (Manufacturing method) The method for forming the resin layer is not particularly limited, but examples include spraying with a paint, dip coating, and roll coating. For example, a resin layer can be formed by applying a resin layer-forming coating liquid to the substrate or an elastic layer formed on the outer surface of the substrate using a known method, and then heating and drying the applied coating liquid. The heating and drying conditions are not particularly limited, and examples include a method of drying at 120 to 200°C. The thickness of the resin layer is also not particularly limited, and is preferably 1 to 50 μm, and more preferably 5 to 20 μm.

[0167] <Process cartridge and electrophotographic image forming apparatus> The developing roller according to the present disclosure can be suitably used as a developing roller in a process cartridge. The process cartridge is equipped with the developing device according to the present disclosure. FIG. 3 is a schematic cross-sectional view of an example of a process cartridge according to one embodiment of the present disclosure. The process cartridge 22 is configured to be detachably mountable to the main body of an electrophotographic image forming apparatus. The process cartridge 22 is an integrated unit of a developing device 18 including a developing roller 14 and a developing blade 15, a photosensitive member 19, a charging roller 20, and a cleaning blade 21. The developing device 18 is further filled with toner 16. The toner 16 is supplied to the developing device 18 by a toner supply roller 17. The toner is supplied to the surface of the developing roller 14 by the developer, and a developing blade 15 forms a layer of toner 16 of a predetermined thickness on the surface of the developing roller 14 .

[0168] The developing roller 14 is in contact with the photosensitive member 19 and is driven to rotate at a predetermined peripheral speed ratio relative to the photosensitive member 19. A predetermined bias is applied to the developing roller 14, and the electrostatic latent image on the photosensitive member 19 is developed with the toner 16 to be visualized.

[0169] The toner supply roller 17 comes into contact with the developing roller 14, penetrates a predetermined amount, and rotates in the same direction as or opposite to the rotation direction of the developing roller 14. A predetermined bias is applied to the toner supply roller 17.

[0170] One end of the developing blade 15 is fixed to the developing device 18, and the other free end is arranged in contact with the developing roller 14 in the counter direction to the rotational direction. By arranging the developing blade 15 in contact with the developing roller 14, the amount of toner on the developing roller 14 is regulated, making the layer thinner and forming a toner layer of uniform thickness. In addition, a predetermined bias is applied to the developing blade 15, imparting an electric charge to the toner 16.

[0171] The developing device has a developing roller 14 and toner 16. The developing device also has a developing blade 15 that contacts the developing roller 14 and regulates the thickness of the layer of toner 16 carried on the developing roller 14, and a contact point electrically connected to the developing blade 15. When the developing device is mounted in the main body of an electrophotographic device, the contact point electrically connects to the main body contact point of the main body of the electrophotographic device, making it possible to apply a predetermined voltage to the developing blade 15. The volume resistivity of the developing blade 15 is 1.0×10 6 It is preferable that the resistivity is Ω·cm or less. This allows the developing blade 15 to form a layer of toner 16 of uniform thickness on the developing roller 14, while at the same time enabling charge injection from the developing blade 15 into the toner, making it easier to uniformly control the amount of charge on the toner.

[0172] An electrophotographic image forming apparatus is provided with the developing device of the present disclosure. Figure 4 is a schematic cross-sectional view showing an example of an electrophotographic image forming apparatus provided with a contact-type developing device using one-component toner. The developing device 18 includes toner 16 as a single-component toner, a developing roller 14, a toner supply roller 17 that supplies toner to the developing roller 14, and a developing blade 15 that regulates the thickness of the toner layer on the developing roller 14. The developing roller 14 is located in an opening extending in the longitudinal direction within the developing device 18 and is installed in contact with the photoconductor 19. Note that the photoconductor 19, charging roller 20, and cleaning blade 21 may be provided in the main body of the electrophotographic image forming apparatus. The developing device 18 is equipped with toner of each color: black, cyan, magenta, and yellow, enabling color printing.

[0173] The printing operation of an electrophotographic image forming apparatus will now be described. Photoconductor 19 rotates in the direction of the arrow and is uniformly charged by charging roller 20, which charges photoconductor 19. Next, an electrostatic latent image is formed on the surface of photoconductor 19 by laser light 23, which serves as exposure means. The electrostatic latent image is visualized as a toner image (developed) by developing device 18, which applies toner 16 from developing roller 14, which is placed in contact with photoconductor 19. Development is what is known as reversal development, in which a toner image is formed in the exposed area.

[0174] The toner image formed on the photosensitive member 19 is transferred onto an intermediate transfer member 25 in the form of an endless belt by a transfer roller 24 which is a transfer member. Paper 26, which is a recording medium, is fed into the device by a paper feed roller 27 and a secondary transfer roller 28, and is transported together with intermediate transfer body 25 carrying a toner image to the nip between secondary transfer roller 28 and driven roller 29, where the toner image is transferred to paper 26. Intermediate transfer body 25 is driven by driven roller 29, drive roller 30, and tension roller 31. The toner remaining on the surface 5 is removed by a cleaning device 32.

[0175] A voltage is applied to the developing roller 14, developing blade 15, transfer roller 24, and secondary transfer roller 28 from a bias power supply 33. The paper 26 onto which the toner image has been transferred is fixed by a fixing device 34 and then ejected outside the device, completing the printing operation. Meanwhile, residual toner remaining on the photoreceptor 19 without being transferred is scraped off by a cleaning blade 21, which is a cleaning member for cleaning the surface of the photoreceptor. The cleaned photoreceptor 19 repeats the above printing operation.

[0176] The methods for measuring the physical properties of each material, toner, and developing roller will be described below. <Method for measuring toner impedance and calculating conductivity> The capacitance and conductivity of air and powder are measured by impedance measurement using the parallel plate capacitor method. The equipment used is a toner measurement jig consisting of a four-terminal sample holder SH2-Z (manufactured by Toyo Corporation) and a torque wrench adapter SH-TRQ-AD (optional), and a material testing system ModuLab XM MTS (manufactured by Solartron Corporation). In addition, a noise-cutting transformer NCT-I3 1.4kVA (manufactured by Denken Seiki Kenkyusho Co., Ltd.) is used to suppress commercial power supply noise, and a shielding box is used to suppress electromagnetic noise.

[0177] The powder measurement jig uses a four-terminal sample holder and the optional torque wrench adapter SH-TRQ-AD, and uses the upper electrode (Φ25mm solid electrode) SH-H25AU and the lower electrode for liquids / powder (center electrode Φ10mm; guard electrode Φ26mm) SH-2610AU as parallel plate electrodes, and is configured to be able to measure resistances of 0.1Ω to 1TΩ for electrical signals of up to 500Vp-p and DC to 1MHz.

[0178] In addition, to adjust the pressure of the toner sample, a torque wrench adapter SH-TRQ-AD (manufactured by Toyo Corporation) was attached to the micrometer used to measure the film thickness between the upper and lower electrodes provided on the four-terminal sample holder. The torque driver used for pressure control is the RTD15CN torque driver (manufactured by Tohnichi Manufacturing Co., Ltd.) with a 6.35 mm square bit, configured to be able to control the tightening torque to 6.5 cN·m.

[0179] The electrical AC characteristics are measured by impedance measurement using a material testing system ModuLab XM MTS (manufactured by Solartron). The ModuLab XM MTS consists of the control module XM MAT 1MHz, the high-voltage module XM MHV100, the femtocurrent module XM MFA, and the frequency response analysis module XM MRA 1MHz, and the control software is the company's own XM-studio MTS Ver.3.4.

[0180] The measurement conditions are Normal Mode, which only performs measurement, with an AC level of 7 Vrms, a DC bias of 0 V, and a sweep frequency of 1 MHz to 0.01 Hz (12 points / decade or 6 points / decade). Furthermore, in consideration of noise suppression and shortening of measurement time, the following settings are added for each sweep frequency. Sweep frequency 1MHz~10Hz Measurement integration time 64 cycles Sweep frequency 10Hz to 1Hz Measurement integration time 24 cycles Sweep frequency 1Hz to 0.01Hz Measurement integration time 1 cycle Under the above measurement conditions, the impedance characteristics, which are the electrical AC characteristics of the toner, are measured.

[0181] By performing measurements under the above conditions, a powder measurement jig based on the parallel plate capacitor method is used, and the impedance characteristics of the air and sample at the film thickness d according to the pressure torque and a measurement electrode S of 10 mm in diameter can be obtained.

[0182] From the obtained impedance characteristics of the air and sample, data correction processing for the measurement system is performed to obtain highly reliable capacitance C and conductance (conductivity) G. From the obtained capacitance C, conductance (conductivity) G, and the geometric shape of the toner measurement jig (parallel plate electrode size S and sample film thickness), the electrical properties of relative permittivity and conductivity are calculated.

[0183] When using the 4-terminal sample holder SH2-Z for the first time, two verifications must be carried out to find the optimal measurement conditions, since there are individual differences in the 4-terminal sample holder SH2-Z used in powder measurement jigs.

[0184] The first verification is the film thickness dependency characteristics of the four-terminal sample holder. The dependency on air thickness (distance between the upper and lower electrodes) is measured, the error between the theoretical value of capacitance and the measured value is confirmed, and the optimal range or film thickness at which the measurement error is minimized is identified.

[0185] The second verification is the measurement of mechanical error. When measuring toner samples, a torque-controlled load is applied to maintain a constant volume density. In contrast, when measuring air, no load is applied. At this time, film thickness errors occur due to the influence of dimensions such as mechanical processing accuracy. Therefore, the offset value when the tightening torque control value (6.5 cN m in this jig) is loaded and unloaded is confirmed, and this is used as the offset correction value.

[0186] The specific sample preparation and measurement procedures are as follows. (1) Toner is piled up on the central electrode portion of the lower electrode and formed into a trapezoidal shape with a height of 5 mm. (2) The lower electrode with the toner piled up is attached to the four-terminal sample holder SH2-Z, and the upper electrode is lowered. (3) At this time, the upper electrode is lowered to the top edge of the toner while being kept constant so as not to rotate accidentally. (4) While rotating the upper electrode left and right, a smoothing process is performed to make the toner smooth. (5) Using a micrometer, adjust the film thickness to a predetermined value while maintaining the rotation direction of the upper electrode in a uniform, constant direction. (6) Apply pressure using a torque driver. (7) Measure the sample film thickness using a micrometer. (8) Impedance measurement is carried out under the above conditions. (9) After the measurement is completed, raise the upper electrode and remove the lower electrode. At this time, remove the lower electrode carefully so that toner does not get into the contact terminal for the lower electrode of the four-terminal sample holder, and protect it with masking tape. (10) Clean the upper and lower electrodes. (11) Remove the masking tape and attach the lower electrode. (12) The sample film thickness d obtained in step (7) is adjusted to the air thickness t, taking into account offset correction in the no-load state, and the rotation direction of the upper electrode is kept constant. (13) Conduct air impedance measurements. (14) If the measurement data (dielectric tangent; tanδ) of the air measured in step (13) is 0.002 or more in the frequency range of 100 Hz to 0.01 Hz, the cleaning is insufficient, so the work is to be started again from the cleaning step (10). The measurement is carried out at 25°C.

[0187] The specific data processing procedure is as follows. (15) From the measured impedance characteristics of air, the error of the phase characteristics relative to the theoretical value is calculated, and phase correction data for the material testing system ModuLab XM MTS (manufactured by Solartron) is obtained. (16) The phase correction data calculated in step (15) is applied to the impedance characteristics of the air measured in step (13) to obtain the phase-corrected impedance characteristics of the air. (17) The capacitance Ca is calculated from the admittance Ya=Ga+jωCa of the phase-corrected impedance characteristic of air, and the error from the theoretical value is calculated to obtain correction data α for the film thickness error. (18) The phase correction process obtained in step (15) is applied to the impedance characteristics of the toner sample measured in step (8). (19) By calculating the complex admittance Ym = Gm + jωCm of the characteristics that have been subjected to the phase correction processing in step (18) using the capacitance Ca of the air obtained in step (17) and its correction data α, the highly reliable relative permittivity and conductivity of the toner sample can be obtained. The resistivity of the toner in this disclosure is the reciprocal of the conductivity at a frequency of 0.01 Hz.

[0188] <Measurement of endothermic peak temperature and endothermic amount of crystalline material in toner> The endothermic peak temperature and endothermic amount of the crystalline material in the toner are measured using a differential scanning calorimeter "Q1000" (manufactured by TA Instruments). The melting points of indium and zinc are used to correct the temperature of the detector, and the heat of fusion of indium is used to correct the amount of heat. Specifically, 3 mg of toner is weighed out and placed in an aluminum pan, with an empty aluminum pan used as a reference. Using modulation measurement mode, measurements are taken in the range of 0°C to 120°C with a temperature rise rate of 1°C / min and temperature modulation conditions of ±0.6°C / 60 seconds. The maximum endothermic peak of the DSC curve in the temperature range of 30 to 200°C during the temperature rise process is taken as the maximum endothermic peak of the endothermic curve in the DSC measurement of the toner, and the temperature of this peak value is taken as the endothermic peak temperature. The endothermic amount is the area of ​​the endothermic peak calculated using the temperature of the shoulder of the endothermic peak occurring at the lowest temperature and 120°C as the baseline. Change the 120°C used in the baseline setting above to 80°C and calculate the endothermic heat from 30 to 80°C.

[0189] <Measurement of the area ratio of crystalline material in the cross section of the toner> The state of the sea-island structure in the cross section of the toner is confirmed by observing the cross section of the toner using a scanning transmission electron microscope. The cross section of the toner is observed after ruthenium staining. The procedure for observing the cross section of the toner is as follows. The toner is dispersed as much as possible, and the sample is embedded in a visible light curable resin (D-800, manufactured by Nissin EM Co., Ltd.), and cut to a thickness of 100 nm using an ultrasonic ultramicrotome (UC7, manufactured by Leica).

[0190] The obtained thin section sample was stained for 15 minutes in a 500 Pa RuO4 gas atmosphere using a vacuum staining device (VSC4R1H, Filgen), and STEM images were taken using a scanning transmission electron microscope (JEM2800, JEOL). Under the above staining conditions, there is a difference in the degree of staining between the crystalline material and the amorphous resin, and the presence of the sea-island structure can be confirmed from this contrast difference.

[0191] Crystalline materials are stained with ruthenium more than amorphous resins. The amount of ruthenium atoms varies depending on the strength of the staining, so areas that are stained strongly have a large amount of these atoms, and the electron beam does not pass through, so they appear black in the observation image, while areas that are stained weakly allow the electron beam to pass through easily, so they appear white in the observation image. In this way, a contrast difference occurs between the crystalline material and the amorphous resin. Therefore, the existence status can be confirmed.

[0192] The observation conditions are set as follows: acceleration voltage 200 kV, STEM probe size 1 nm, image size 1024 × 1024 pixels, magnification 30000, and dark field (STEM-DF) images are acquired. Contrast and Brightness are adjusted so that the brightness when the maximum number of pixels in the area mainly composed of resin components is 150 in the brightness histogram by IMAGE J shown below. If the brightness is between 140 and 160, you can adjust the brightness using Microsoft Photos. If the brightness is other than the above, change the staining conditions again and obtain a new STEM image.

[0193] In this case, when selecting the cross-sectional image of the toner, the weight average particle diameter (D4) of the toner is measured by the measurement method described later, and then 10 cross-sections of toner particles having a major axis diameter 0.8 to 1.1 times the D4 are selected. In addition, the image is acquired so that two or more toner particles do not fit within the field of view of one image.

[0194] The brightness histogram is obtained by analyzing the STEM image of the toner cross section obtained by the above method using the image processing software Image J (developed by Wayne Rashand). In other words, the brightness histogram is a brightness histogram obtained when a 256-level brightness spectrum is measured for the image obtained from the image analysis of the toner cross section. The specific procedure is shown below.

[0195] First, convert the backscattered electron image to be analyzed to 8-bit using Type in the Image menu. Next, the analysis range is specified to be only the area inside the toner outline. Here, the boundary of the toner outline is the interface between the visible light curable resin and the toner cross section. Clear the area outside the analysis range by selecting Clear Outside from the Edit menu. From the Filters menu in the Process menu, set the Median diameter to 2.0 pixels to reduce image noise.

[0196] Next, select "Threshold" from "Adjust" in the "Image" menu, set the position of the bottom bar to 150, and select "Apply." Display the list and calculate the white ratio from the number of 0 pixels to the total number of pixels. This white ratio is the area ratio of crystalline material. The same image analysis is performed on 10 STEM images of the cross section of each toner, and the above values ​​are calculated. The arithmetic mean of the obtained values ​​for the 10 images is taken as the physical property value of each toner.

[0197] <How to confirm the sea-island structure and measure the dispersion diameter> The sea-island structure is, for example, a state in which, in a toner cross-sectional image, seas are connected within the image and islands are separated by seas. In the STEM image of the toner cross section, the black-stained, connected areas are identified as islands of crystalline material. The major and minor axes of these islands of crystalline material are measured, and the average of the major axis values ​​for all the observed toner particles is taken as the average particle size of the crystalline material.

[0198] In addition, in the STEM image of the toner cross section, the divided parts that are not stained black are assumed to be a sea of ​​amorphous resin. Regarding the sea-island structure, specifically, when two or more islands separated by a sea are observed in the 10 STEM images of the toner cross section, as described above, it is determined that the toner has a sea-island structure.

[0199] <Measuring method for volume average particle size (Dv)> The volume average particle size (Dv) of the toner is calculated as follows. The measurement device used is a particle counting analyzer "CDA-1000X" (manufactured by Sysmex Corporation) equipped with a 100 μm aperture tube and employing the pore electrical resistance method. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software "CDA-1000X (manufactured by Sysmex Corporation)." The aqueous electrolyte solution used for the measurement may be, for example, "Cell Pack" (manufactured by Sysmex Corporation). Before carrying out the measurements and analysis, the dedicated software was set up as follows. On the "measurement condition setting" screen of the dedicated software, set the total count number to 50,000, the number of repeated measurements to 1, and the measurement mode to total count (no limit).

[0200] The specific measurement method is as follows. (1) Pour approximately 150 ml of the electrolyte solution into a dedicated glass round-bottom beaker, set it on the sample stage, and stir with the stirring propeller at 500 rpm. Then, click "Blank Check Measurement" in the dedicated software to start the measurement and confirm that the count is less than 500. If the count is 500 or more, repeatedly clean the beaker and aperture tube. (2) 30 ml of the above-mentioned electrolyte solution is placed in a 100 ml flat-bottom glass beaker, and 0.3 ml of a solution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) three times by weight with ion-exchanged water is added as a dispersant. (3) Prepare an ultrasonic disperser "Ultrasonic Dispension System Tetra150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two built-in oscillators with an oscillation frequency of 50 kHz and a phase difference of 180 degrees. Place approximately 3.3 L of ion-exchanged water in the ultrasonic disperser's water tank and add 2 mL of Contaminon N to this water tank. (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized. (5) While ultrasonic waves are irradiated into the electrolyte solution in the beaker from (4), 10 mg of toner is added little by little and dispersed. Then, the ultrasonic dispersion process is continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted so that it is between 10°C and 40°C. (6) Using a pipette, the electrolytic solution (5) containing the dispersed toner is dropped into the round-bottom beaker (1) placed in the sample stand, and the measurement concentration is adjusted to 6%. Then, measurements are continued until the number of particles measured reaches 50,000. (7) The measurement data is analyzed using the dedicated software provided with the device to calculate the volume average particle size (Dv).

[0201] <Toner composition analysis> Separation of toner particles from toner The toner particles obtained by separating the toner particles from the external additives by the following method can be used for each analysis. Add 160 g of sucrose (Kishida Chemical) to 100 mL of ion-exchanged water and dissolve in a hot water bath to prepare a sucrose solution. Place 31 g of the sucrose solution and 6 mL of Contaminon N (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a centrifuge tube to prepare a dispersion. Add 1 g of toner to this dispersion and break up any clumps of toner with a spatula or similar.

[0202] The centrifuge tube is placed in a KM Shaker (model V.SX) manufactured by Iwaki Sangyo Co., Ltd. and shaken for 20 minutes at 350 strokes per minute. After shaking, the solution is transferred to a glass tube (50 mL) for a swing-out rotor and centrifuged at 3500 rpm for 30 minutes in a centrifuge (H-9R manufactured by Kokusan Co., Ltd.). After centrifugation, the toner particles are in the top layer of the glass tube, and external additives such as silica microparticles are in the aqueous solution below. The toner particles in the top layer are collected and filtered, then washed with 2 L of ion-exchanged water heated to 40°C, and the washed toner particles are removed.

[0203] A method for separating chloroform-soluble matter and chloroform-insoluble matter (crystalline resin) from toner particles 1.5 g of toner particles are weighed out and placed in a pre-weighed cylindrical filter paper (product name: No. 86R, size 28 × 100 mm, manufactured by Advantec Toyo Co., Ltd.) and set in a Soxhlet extractor. Extraction is performed for 18 hours using 200 mL of chloroform as the solvent, with the reflux speed set so that the solvent extraction cycle occurs approximately once every 5 minutes. After the extraction is complete, the thimble is removed and air-dried, and then vacuum-dried at 40°C for 8 hours. The mass of the thimble containing the extraction residue is weighed and subtracted from the mass of the thimble to confirm the mass of the extraction residue (chloroform-insoluble matter (crystalline resin)). This confirms that the insoluble matter has been recovered. The chloroform-soluble matter can be recovered by thoroughly distilling off the chloroform from the soluble matter in the chloroform using an evaporator.

[0204] ·Method for separating amorphous resin and wax from chloroform soluble matter The amorphous resin and wax are separated using recycle HPLC, with components with a molecular weight of 2000 or less considered to be wax. The measurement method is as follows: First, the chloroform-soluble components are separated using the method described above and dissolved in chloroform. The resulting solution is then filtered through a solvent-resistant membrane filter "Myshoridisc" (manufactured by Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of chloroform-soluble components is 1.0 mass%. This sample solution is used to perform measurements under the following conditions.

[0205] ·Equipment: LC-Sakura NEXT (manufactured by Japan Analytical Industry Co., Ltd.) Column: JAIGEL 2H, 4H (Japan Analytical Industry Co., Ltd.) Eluent: Chloroform ·Flow rate: 10.0mL / min Oven temperature: 40.0℃ Sample injection volume: 1.0 mL The molecular weight of the sample is calculated using a molecular weight calibration curve prepared using standard polystyrene resins (for example, trade names "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500" manufactured by Tosoh Corporation). From the molecular weight curve thus obtained, components with a molecular weight of 2000 or less are repeatedly separated, and the amorphous resin component and wax component in the chloroform-soluble matter of the toner are separated.

[0206] -Identification of components and mass ratios of amorphous resins and crystalline materials using nuclear magnetic resonance spectroscopy (NMR) Add 1 mL of deuterated chloroform to 20 mg each of amorphous resin, wax, and crystalline resin. 1 H-NMR was performed under the following conditions.

[0207] Measuring device: FT NMR device JNM-EX400 (manufactured by JEOL Ltd.) Measurement frequency: 400MHz Pulse condition: 5.0 μs Frequency range: 10500Hz Accumulation count: 64 times Measurement temperature: 30℃ Sample: Prepared as follows: 50 mg of the measurement sample is placed in a sample tube with an inner diameter of 5 mm, deuterated chloroform (CDCl3) is added as a solvent, and the sample is dissolved in a thermostatic bath at 40°C to prepare the sample.

[0208] obtained 1 The H-NMR chart is analyzed to identify the structure of each unit. When a monomer that does not contain a hydrogen atom in any component other than the vinyl group is used, 13 Measured nuclei using C-NMR 13 C, and measurements were taken in single pulse mode. 1 The content of each unit can be converted to mass % by multiplying the proportion (mol %) of each unit calculated by the above method by the molecular weight of each unit.

[0209] <Measurement of the impedance of the developing roller> The impedance of the developing roller was measured as follows. First, as a pretreatment, a measurement electrode was created by vacuum vapor deposition of platinum onto the developing roller while it was rotating. Vacuum deposition was performed using a vacuum deposition device with a mechanism for gripping the base of the roller (the object to be deposited) and rotating it circumferentially. The roller rotation speed, deposition distance, and deposition time were controlled to deposit a film thickness of 100 nm or more. A 1.5 cm wide electrode was created using masking tape. By forming the electrode with a thickness of 100 nm or more, the contribution of the contact area between the measuring electrode and the developing roller, which is caused by the surface roughness of the developing roller, can be minimized.

[0210] Next, an aluminum sheet was wrapped tightly around the electrode, and the aluminum sheet was connected to the measurement electrodes of an impedance measuring device (product names: Solartron 1260 and Solartron 1296, manufactured by Solartron Corporation) and a high-voltage system (product names: 6792 and HVA-500, manufactured by Toyo Corporation).

[0211] Figure 5 shows a schematic diagram of the state in which the measurement electrodes are formed on the developing roller. In Figure 5, 51 is a conductive substrate, 52 is a resin layer, 53 is a platinum vapor deposition layer, and 54 is an aluminum sheet. In this figure, the elastic layer is not shown, but it exists between the substrate 51 and the resin layer 52.

[0212] Figure 6 shows a cross-sectional view of the developing roller with the measurement electrode formed on it. 61 is the conductive substrate, 62 is the elastic layer, 63 is the resin layer, 64 is the platinum vapor deposition layer, and 65 is the aluminum sheet. As shown in Figure 6, it is important to sandwich the resin layer between the conductive substrate and the measurement electrode.

[0213] The aluminum sheet was then connected to the measurement electrodes of an impedance measurement device (Solatron 1260 and Solartron 1296, manufactured by Solartron) and a high-voltage system (product names: 6792 and HVA-500, manufactured by Toyo Corporation). Figure 7 shows a schematic diagram of this measurement system. Impedance measurements were performed using the conductive substrate and the aluminum sheet as the two electrodes for measurement.

[0214] The impedance was measured at a temperature of 23°C and a relative humidity of 50%, with a DC voltage of 50V and an AC voltage of 50V applied, and a frequency of 1.0 x 10 -1 ~1.0×10 5 The absolute value of the impedance was obtained in Hz. And, at a frequency of 1.0 x 10 2 Impedance Z in Hz, frequency 1.0 x 10 2 Phase θ1 and frequency 1.0×10 Hz 4 The phase θ2 in Hz was obtained.

[0215] <Surface potential> In an environment with a temperature of 23°C and a relative humidity of 50%, a corona discharger with a 3.0 mm wide grid was placed so that the distance between the grid and the outer surface of the developing roller was 1.0 mm and the width direction of the grid was aligned with the axial direction of the developing roller. A voltage of 8 kV was applied to the grid, and the corona discharger was moved relative to the developing roller in the axial direction at a speed of 400 mm / s to charge the outer surface of the developing roller. The potential of the outer surface 0.06 seconds after passing the grid was measured, and the degree of overcharging (charge-up) of the toner was evaluated.

[0216] The surface potential of the developing roller can be measured, for example, using the device shown in Figure 8. Both ends of substrate 82 of developing roller 81 are held by chucks 83, and a measuring unit 86, which includes a corona discharger 84 and a surface electrometer 85 arranged in parallel with a 25 mm gap between them, is positioned facing the surface of developing roller 81 at a distance of 1.0 mm. With developing roller 81 stationary, a voltage of 8 kV is applied to the grid portion of corona discharger 84, and measuring unit 86 is moved in the axial direction of developing roller 81 at a speed of 400 mm / sec. The surface potential is measured by surface electrometer 85 0.06 seconds after passing through corona discharger 84.

[0217] A voltage of 8 kV is applied to the grid portion, and the corona discharger is moved relatively along the axial direction of the developing roller at a speed of 400 mm / sec. The potential of the outer surface of the developing roller is checked 0.06 seconds after the grid portion of the corona discharger has passed. If the maximum value of the potential of the outer surface is less than 20.0 V, the time it takes for the toner charged by the developing blade to be transported to the photosensitive member is shorter, and the occurrence of image defects due to excessive charging of the toner can be suppressed even in electrophotographic image forming apparatuses with high process speeds. Note that 0.06 seconds after passing through the grid part of the corona discharger simulates a model with high process speed.

[0218] <Measurement of the number average diameter of primary particles of conductive fine particles> The number-average diameter of the primary particles of the conductive fine particles dispersed in the resin was measured using a transmission electron microscope (TEM). First, a thinned sample was prepared. A known method can be used for thinning. For example, the sample can be thinned using an ion beam or a diamond knife. In this disclosure, a 40 nm thick thinned sample for observation was prepared using an ultramicrotome (product name: ULTRACUT-S, manufactured by Leica Microsystems). Then, a TEM image was obtained using a transmission electron microscope (product name: H-7100FA, manufactured by Hitachi High-Technologies Corporation) under measurement conditions of TE mode and an accelerating voltage of 100 kV. Then, using image analysis software (product name: WinROOF, manufactured by Mitani Shoji Co., Ltd.) for the obtained TEM image, the circular equivalent diameters of 50 primary particles of the selected conductive microparticles were measured, and the number average value of the 50 particles was taken as the number average diameter of the primary particles.

[0219] <Measurement of DBP absorption amount of carbon black> The DBP absorption amount of carbon black was measured for carbon black powder in accordance with Japanese Industrial Standards (JIS) K6217-4.

[0220] <Measurement of pH of carbon black> The pH of the carbon black was measured on the carbon black powder according to ASTM D1512.

[0221] <Calculation of various physical properties such as the equivalent circle diameter and wall distance of conductive particles dispersed in a resin layer> The equivalent circle diameter and wall-to-wall distance of the conductive fine particles dispersed in the resin layer were measured by the following method. First, use a razor to cut out a section (0.5 to 1.0 mm thick) so that the cross section perpendicular to the longitudinal direction of the developing roller can be observed. If the adhesion between the substrate and the resin layer is high and it is difficult to cut out with a razor, cut out the entire substrate with a hacksaw or similar tool, and then use FIB (Focused Ion Beam). d) Cross-section processing is performed using an Ion Beam (focused ion beam) device.

[0222] Next, the slice is platinum-deposited, and the resin layer is photographed at 15,000x magnification using a scanning electron microscope (trade name: JSM-7800F, manufactured by JEOL Ltd.) to obtain a cross-sectional image. Furthermore, to quantify the cross-sectional images obtained by SEM observation, the cross-sectional images were converted to 8-bit grayscale using image processing software (product name: Luzex AP, manufactured by Nireco Corporation) to obtain a monochrome image with 256 gradations. Next, the black and white of the image were inverted so that the carbon black in the cross-sectional image appeared white, and then a binarization threshold was set for the brightness distribution of the image based on the algorithm of Otsu's discriminant analysis method, obtaining a binarized image in which the conductive particles appeared white and the binder resin appeared black.

[0223] Then, using image processing software (product name: Luzex AP, manufactured by Nireco Corporation) on the obtained binary image, the equivalent circle diameter and the distance between adjacent wall surfaces of the whitened conductive particle parts are calculated. The equivalent circle diameter and the distance between adjacent wall surfaces are calculated. In order to eliminate the uncertainty of the calculated values ​​for conductive particles that are divided at the top, bottom, left, and right edges of the image, the image area is set to an area 0.075 μm inside in actual image dimensions (if there is a text area describing the SEM measurement conditions, etc., it is set to 0.075 μm inside from where the actual image begins), and the equivalent circle diameter and the distance between adjacent wall surfaces are calculated for all conductive particles within the specified image area.

[0224] Then, the arithmetic mean value and standard deviation are calculated for the distribution of the obtained circle equivalent diameter and the distance between adjacent wall surfaces. In order to eliminate the influence of differences in the longitudinal direction of the conductive fine particles dispersed in the resin layer of the developing roller, the developing roller was divided into 10 equal sections in the longitudinal direction, and the arithmetic mean of the circle-equivalent diameters and the distances between adjacent wall surfaces of the 10 sections was used as the circle-equivalent diameter and the distances between adjacent wall surfaces in the present disclosure.

[0225] <Measurement of weight average molecular weight (Mw) and number average molecular weight of raw materials> The apparatus and conditions used to measure the weight average molecular weight (Mw) and number average molecular weight (Mn) of raw materials such as resins are as follows. Measuring device: HLC-8120GPC (Tosoh Corporation) Column: TSKgel Super HZMM (Tosoh Corporation) x 2 Solvent: tetrahydrofuran (THF) (20 mmol / l triethylamine added) Temperature: 40℃ THF flow rate: 0.6 ml / min The measurement sample was a 0.1% by mass THF solution. Furthermore, the measurement was carried out using an RI (refractive index) detector as the detector. A calibration curve was created using TSK standard polystyrenes A-1000, A-2500, A-5000, F-1, F-2, F-4, F-10, F-20, F-40, F-80, and F-128 manufactured by Tosoh Corporation as standard samples for creating a calibration curve. Based on this calibration curve, the weight average molecular weight and number average molecular weight were calculated from the retention times of the obtained measurement samples. [Example]

[0226] The following examples are provided for a more detailed explanation. In the following formulations, "parts" refers to "parts by mass" unless otherwise specified.

[0227] (Preparation of Crystalline Resin 1) The following materials were placed in a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube under a nitrogen atmosphere. Toluene 100.0 parts Monomer composition 100.0 parts (The monomer composition is a mixture of the following monomers in the ratio shown below.) (Behenyl acrylate 60.0 parts) (styrene 20.0 parts) (Methacrylonitrile 10.0 parts) (N-vinyl-2-pyrrolidone 10.0 parts) Polymerization initiator: 0.5 parts t-butyl peroxypivalate (NOF Corporation: Perbutyl PV) The materials were heated to 70°C in a reaction vessel while stirring at 200 rpm, and the polymerization reaction was carried out for 12 hours, resulting in a solution in which the polymer in the monomer composition was dissolved in toluene. The solution was then cooled to 25°C, and then poured into 1000 parts of methanol with stirring to precipitate the methanol-insoluble matter. The resulting methanol-insoluble matter was filtered, washed with methanol, and vacuum-dried at 40°C for 24 hours to obtain Crystalline Resin 1. The physical properties of Crystalline Resin 1 are shown in Table 1.

[0228] (Preparation of Crystalline Resins 2 and 3) Crystalline resins 2 and 3 were prepared in the same manner as in the preparation of crystalline resin 1, except that the amount of the monomer composition added was changed to that shown in Table 1. The physical properties of crystalline resins 2 and 3 are shown in Table 1.

[0229] [Table 1] Polymerization initiator: t-butyl peroxypivalate (NOF Corporation: Perbutyl PV)

[0230] [Toner manufacturing example] <Production of Toner 1> A mixture of the following materials was prepared: Styrene 45.0 parts 15.0 parts n-butyl acrylate Carbon black 6.5 parts Aluminum di-t-butyl salicylate 0.1 parts The mixture was placed in an attritor (manufactured by Nippon Coke and Engineering Co., Ltd.) and dispersed at 200 rpm for 2 hours using zirconia beads with a diameter of 5 mm, to obtain a raw material dispersion.

[0231] Meanwhile, 735.0 parts of ion-exchanged water and 16.0 parts of trisodium phosphate (12-hydrate) were added to a container equipped with a high-speed stirring device, a homomixer (manufactured by Primix Corporation), and a thermometer, and the temperature was raised to 60°C while stirring at 12,000 rpm. An aqueous calcium chloride solution prepared by dissolving 9.0 parts of calcium chloride (dihydrate) in 65.0 parts of ion-exchanged water was added thereto, and the mixture was stirred at 12,000 rpm for 30 minutes while maintaining the temperature at 60°C. 10% hydrochloric acid was added thereto to adjust the pH to 6.0, and an aqueous medium in which an inorganic dispersion stabilizer containing hydroxyapatite was dispersed in water was obtained.

[0232] Subsequently, the raw material dispersion was transferred to a container equipped with a stirrer and a thermometer, and the temperature was raised to 60° C. while stirring at 100 rpm. ·Crystalline resin 1: 45.0 parts Dipentaerythritol stearate wax, melting point 79°C, manufactured by Nisshin Oillio Group Co., Ltd.: 9.0 parts HDDA (hexanediol diacrylate): 0.2 parts After heating to 60°C, the above materials were added and stirred at 100 rpm for 30 minutes while maintaining the temperature at 60°C, and then 8.0 parts of t-butyl peroxypivalate (Perbutyl PV, manufactured by NOF Corporation) was added as a polymerization initiator and stirred for another minute, after which the mixture was poured into the aqueous medium being stirred at 12,000 rpm with the high-speed stirrer. Stirring was continued at 12,000 rpm with the high-speed stirrer while maintaining the temperature at 60°C for 20 minutes to obtain a granulation liquid.

[0233] The granulation liquid was transferred to a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube, and heated to 76° C. while stirring at 150 rpm under a nitrogen atmosphere. A polymerization reaction was carried out at 150 rpm for 6 hours while maintaining the temperature at 76° C., thereby obtaining a toner particle dispersion liquid.

[0234] The resulting toner particles were heated to 80°C and held there for 30 minutes. Then, they were cooled from 80°C to 50°C at a rate of 10°C / sec. They were then annealed for 10 hours while stirring at 150 rpm, maintaining the temperature at 50°C. After annealing, the mixture was slowly cooled to room temperature, and dilute hydrochloric acid was added with stirring until the pH reached 1.5 to dissolve the dispersion stabilizer. The solids were filtered, thoroughly washed with ion-exchanged water, and vacuum-dried at 30°C for 24 hours. They were then classified using an inertial classification elbow jet classifier (manufactured by Nittetsu Mining Co., Ltd.) to obtain toner particles 1 with a volume average particle size of 6.5 μm.

[0235] For 1:98.0 parts of the toner particles, silica fine particles (hydrophobized with hexamethyldisilazane, number average particle diameter of primary particles: 10 nm, BET specific surface area: 170 m) were used as an external additive. 2 2.0 parts of ethanol (1.0 parts / g) was added and mixed at 3000 rpm for 15 minutes using a Henschel mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) to obtain Toner 1. The physical properties of the obtained Toner 1 are shown in Table 4.

[0236] <Toner 2 and 3 manufacturing example> Toners 2 and 3 were obtained in the same manner as in the production example of Toner 1, except for the changes shown in Table 2. The physical properties of Toners 2 and 3 obtained are shown in Table 4.

[0237] [Table 2]

[0238] <Toner 4 manufacturing example> A mixture of the following materials was prepared: Styrene 75.0 parts 25.0 parts n-butyl acrylate Carbon black 6.5 parts Aluminum di-t-butyl salicylate 0.1 parts The mixture was placed in an attritor (manufactured by Nippon Coke and Engineering Co., Ltd.) and dispersed at 200 rpm for 2 hours using zirconia beads with a diameter of 5 mm, to obtain a raw material dispersion.

[0239] Meanwhile, 735.0 parts of ion-exchanged water and 16.0 parts of trisodium phosphate (12-hydrate) were added to a container equipped with a high-speed stirring device, a homomixer (manufactured by Primix Corporation), and a thermometer, and the temperature was raised to 60°C while stirring at 12,000 rpm. An aqueous calcium chloride solution prepared by dissolving 9.0 parts of calcium chloride (dihydrate) in 65.0 parts of ion-exchanged water was added thereto, and the mixture was stirred at 12,000 rpm for 30 minutes while maintaining the temperature at 60°C. 10% hydrochloric acid was added thereto to adjust the pH to 6.0, and an aqueous medium in which an inorganic dispersion stabilizer containing hydroxyapatite was dispersed in water was obtained.

[0240] Subsequently, the raw material dispersion was transferred to a container equipped with a stirrer and a thermometer, and the temperature was raised to 60° C. while stirring at 100 rpm. FCA-5 (product name, manufactured by Fujikura Kasei) 2.0 parts 35.0 parts dipentaerythritol stearate wax, melting point 79°C, manufactured by Nisshin Oillio Group Co., Ltd. HDDA (hexanediol diacrylate) 0.2 parts After heating to 60°C, the above materials were added and the mixture was stirred at 100 rpm for 30 minutes while maintaining the temperature at 60°C. After stirring for 1 minute, 10.0 parts of t-butyl peroxypivalate (Perbutyl PV, manufactured by NOF Corporation) was added as a polymerization initiator, and after stirring for another 1 minute, the mixture was poured into the aqueous medium being stirred at 12,000 rpm with the high-speed stirrer. Stirring was continued at 12,000 rpm with the high-speed stirrer for 20 minutes while maintaining the temperature at 60°C, to obtain a granulation liquid.

[0241] The granulation liquid was transferred to a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube, and heated to 76° C. while stirring at 150 rpm under a nitrogen atmosphere. A polymerization reaction was carried out at 150 rpm for 6 hours while maintaining the temperature at 76° C., thereby obtaining a toner particle dispersion liquid.

[0242] The resulting toner particles were heated to 80°C and held there for 30 minutes, then cooled from 80°C to 50°C at a rate of 10°C / sec. Then, while stirring at 150 rpm, they were annealed for 10 hours while maintaining the temperature at 50°C. After annealing, the mixture was slowly cooled to room temperature, and while stirring, dilute hydrochloric acid was added until the pH reached 1.5 to dissolve the dispersion stabilizer. The solids were filtered, thoroughly washed with ion-exchanged water, and then vacuum-dried at 30°C for 24 hours to obtain toner particles 4.

[0243] For 98.0 parts of the toner particles, silica fine particles (hydrophobized with hexamethyldisilazane, number average particle diameter of primary particles: 10 nm, BET specific surface area: 170 m) were used as an external additive. 2 2.0 parts of ethanol (1.0 parts / g) was added and mixed at 3000 rpm for 15 minutes using a Henschel mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) to obtain Toner 4. The physical properties of the obtained Toner 4 are shown in Table 3.

[0244] <Production example of toners 5 to 12> Toners 5 to 12 were obtained in the same manner as in the production example of Toner 4, except for the changes shown in Table 3. The physical properties of Toners 5 to 12 obtained are shown in Table 4.

[0245] [Table 3]

[0246] [Table 4] In the table, the resistivity of the toner indicates the resistivity at a frequency of 0.01 Hz obtained by AC impedance measurement. 13 " indicates that The crystalline material ratio of the toner cross section indicates the area ratio (%) of the crystalline material. The presence or absence of sea-island structures was recorded as "present" if the amorphous resin and ester wax formed a sea-island structure in the toner cross section, and "absent" if they did not. Note that the presence or absence of sea-island structures was not confirmed for toners 1 to 3.

[0247] <Developing roller manufacturing example> In this embodiment, a developing roller in which a resin layer is coated on an elastic roller having an elastic layer provided on the outer surface of a base body will be described, but the present disclosure is not limited to this configuration. <1. Preparation and manufacturing of raw materials for forming resin layer> <1-1. Preparation of raw polyol and manufacturing example> A synthesis example for obtaining a polyurethane resin layer will be shown below. [Preparing raw polyol] The five raw material polyols A-1 to A-5 shown in Table 5 below were purchased commercially.

[0248] [Table 5]

[0249] <1-2. Preparation of raw material isocyanates B-1 to B-3> The raw material isocyanates shown in Table 6 below were prepared.

[0250] [Table 6]

[0251] <1-3. Production Examples of Hydroxyl-Terminated Urethane Prepolymers C-1 to C-3> [Synthesis of hydroxyl-terminated urethane prepolymer C-1] The following materials were reacted under a nitrogen atmosphere by heating and stirring at 90°C for 3 hours. Raw material polyol A-1: ​​100 parts by mass Raw material isocyanate B-1: 6.3 parts by mass Thereafter, 2-butanone (MEK) was added to the resulting reaction product to prepare a solution with a solid content of 50 parts by mass, thereby producing hydroxyl group-terminated urethane prepolymer C-1.

[0252] [Synthesis of Hydroxyl-Terminated Urethane Prepolymers C-2 to C-3] Hydroxyl-terminated urethane prepolymers C-2 and C-3 were prepared in the same manner as C-1, using the starting materials listed in Table 7 below.

[0253] [Table 7]

[0254] <1-4. Production Examples of Isocyanate-Terminated Prepolymers D-1 to D-3> [Synthesis of isocyanate-terminated prepolymer D-1] The following materials were reacted under a nitrogen atmosphere by heating and stirring at 90°C for 3 hours. Raw material polyol A-4: 100 parts by mass Raw material isocyanate B-2: 33.5 parts by mass Thereafter, 2-butanone (MEK) was added to the obtained reaction product to prepare a solution with a solid content of 50 parts by mass, thereby producing an isocyanate group-terminated prepolymer D-1.

[0255] [Synthesis of isocyanate-terminated prepolymers D-2 to D-3] Isocyanate group-terminated prepolymers D-2 and D-3 were prepared using the types and amounts of starting materials shown in Table 8 below in the same manner as in the synthesis of isocyanate group-terminated prepolymer D-1.

[0256] [Table 8]

[0257] [2. Preparation and manufacturing of resin layer additive raw materials] <2-1. Preparation and Production Examples of Polyoxyethylene Polyoxypropylene Alkyl Ethers E-1 and E-2> [Preparation of polyoxyethylene polyoxypropylene alkyl ether] Additives E-1 and E-2 shown in Table 9 below, which are polyoxyethylene polyoxypropylene alkyl ethers, were purchased as commercially available products.

[0258] <2-3. Preparation of polyoxyethylene alkyl ether acetic acid, manufacturing example> [Preparation of polyoxyethylene alkyl ether acetic acid] E-3, which is a polyoxyethylene alkyl ether acetic acid as an additive, was synthesized as shown in Table 9 below.

[0259] [Synthesis of Polyoxyethylene Alkyl Ether Acetic Acid E-3] 55.0 g of polyoxyethylene methyl ether (trade name: Brownon MP-550, manufactured by Aoki Oil & Fat Chemicals Co., Ltd.; average molar addition of ethylene oxide to alcohol: 12 mol) was mixed with 510 ml of 1 mol / L aqueous sodium hydroxide solution, and 71.1 g of potassium permanganate was added and stirred at room temperature for 6 hours. Then, 760 ml of 2-propanol was added and stirred for 1 hour to quench the excess potassium permanganate. The by-product manganese oxide was filtered. The aqueous layer was extracted with dichloromethane and purified to obtain polyoxyethylene methyl ether acetate E-3.

[0260] [Table 9]

[0261] [3. Production examples of coating solutions F-1 to F-17 for forming resin layers] <3-1. Preparation of coating solution F-1 for forming resin layer> Hydroxyl group-terminated urethane polymer C-1: 100 parts by mass Isocyanate-terminated urethane polymer D-3: 54.7 parts by mass Additive E-1: 7 parts by weight Carbon black (product name: MA8, Mitsubishi Chemical Corporation): 35 parts by mass Roughening particles (product name: Art Pearl C-400T, Negami Industrial Co., Ltd.): 23 parts by weight The above materials were added to a reaction vessel and stirred. Next, 2-butanone (MEK) was added so that the total solids ratio was 30% by mass, and then the mixture was mixed using a sand mill. Next, 2-butanone (MEK) was added to adjust the viscosity of the liquid to within the range of 6 to 10 mPa·s, producing resin layer forming paint F-1.

[0262] <3-2. Preparation of coating solutions F-2 to F-17 for forming resin layer> Resin layer-forming coating solutions F-2 to F-17 were prepared in the following manner. First, the hydroxyl-terminated urethane prepolymer, isocyanate-terminated prepolymer, additives, carbon black, and roughening particles listed in Table 10 below were mixed in the same manner as in the preparation of resin layer-forming coating solution F-1. 2-Butanone (MEK) was then added to adjust the viscosity of the solution to within the range of 6 to 10 mPa·s, producing resin layer-forming coating solutions F-2 to F-17.

[0263] [Table 10] A-187 indicates a silane coupling agent (product name: A-187, manufactured by Momentive Corporation). vinegar.

[0264] <4. Manufacturing Example of Developing Roller 1> [4-1. Adjustment of the base] As a substrate, a 6 mm diameter core bar made of stainless steel (SUS304) was prepared by applying a primer (product name: DY35-051, manufactured by Dow Toray Industries, Inc.) to the circumferential surface and baking it.

[0265] [4-2. Preparation of Elastic Layer] Liquid silicone rubber (product name: SE6724A / B, Dow Toray Industries, Inc.) 100.00 parts by mass Carbon black (product name: Toka Black #4300, Tokai Carbon Co., Ltd.) 16.00 parts by mass Curing inhibitor (product name: 1-ethynyl-1-cyclohexanol, Tokyo Chemical Industry Co., Ltd.) 0.01 part by mass ·Platinum catalyst (product name: SIP6830.3, GELEST) 0.01 part by mass The substrate was placed in a mold, and an addition-type silicone rubber composition containing the above materials was poured into the cavity formed in the mold.

[0266] Next, the mold was heated to vulcanize and harden the silicone rubber at a temperature of 150°C for 15 minutes, and after demolding, it was further heated at a temperature of 180°C for 1 hour to complete the hardening reaction, resulting in an elastic roller with an elastic layer with a diameter of 11.5 mm on the outer periphery of the base body.

[0267] [4-3. Preparation of resin layer] The elastic roller was oriented with its longitudinal direction in the vertical direction, and its upper end was gripped and immersed (dipped) in the resin layer-forming coating solution F-1 to coat the surface of the elastic roller with the coating solution. The resulting coating was air-dried at room temperature for 30 minutes and then dried for 1 hour in a hot air circulating dryer set at 160°C. In this way, developing roller 1 was obtained, in which a resin layer with a thickness of 12 μm was formed on the elastic layer. The physical properties of the resulting developing roller 1 are shown in Table 11.

[0268] <Manufacturing Examples of Developing Rollers 2 to 17> Developing rollers 2 to 17 were produced in the same manner as in the manufacturing example of developing roller 1, except that the coating materials for forming the developing roller surface layer were changed to (F-2 to F-17). The physical properties of the resulting developing rollers 2 to 17 are shown in Table 11. The developing rollers 2 to 16 had one elementary process.

[0269] [Table 11]

[0270] An entry such as "9.12+06" would be "9.12 x 10 6 The surface potential is The maximum value indicates the maximum potential when the outer surface of the developing roller is charged by a corona discharger and the potential of the outer surface is measured 0.06 seconds after the end of charging.

[0271] <Examples 1 to 28 and Comparative Examples 1 to 7> The above toners 1 to 12 and developing rollers 1 to 17 were used in the combinations shown in Table 12 to carry out the following toner evaluation and image evaluation. In each example and comparative example, the items for which an evaluation was carried out are marked with a circle.

[0272] [Table 12]

[0273] The evaluation methods and evaluation criteria of the present disclosure will be described below. <Method for Evaluating Toner Fixation> The toners of Example 1, Examples 15 to 25, and Comparative Example 1 were each evaluated as follows.

[0274] <Low temperature fixability> Toner filled process cartridge (Laser Beam Printer (LBP-71 A process cartridge for a Canon LBP-712Ci (manufactured by Canon Inc.) was left at 25°C and 40% RH for 48 hours. A modified Canon LBP-712Ci laser beam printer was used to print an unfixed image with an image pattern in which 10mm x 10mm square images were evenly spaced across the entire transfer paper at 9 points. The toner coverage on the transfer paper was 0.80mg / cm. 2 The transfer paper was A4 size paper (Prober Bond paper: 105 g / m 2 (Fox River) was used. The fixing unit used was an external fixing unit that had been modified so that the fixing unit of a laser beam printer (LBP-712Ci, manufactured by Canon Inc.) could be removed and operated outside the laser beam printer. The fixing temperature of the external fixing unit was increased in 5°C increments from 90°C, and fixing was performed at a process speed of 360 mm / s. The fixed image was visually inspected, and the lowest temperature at which cold offset did not occur was taken as the fixing initiation temperature, and the low-temperature fixability was evaluated.

[0275] <Hot offset resistance> The aforementioned <1> Under the same conditions as in the evaluation of 1), the highest temperature at which hot offset was not observed was taken as the maximum fixing temperature, and the difference Δ° C. between the maximum fixing temperature and the minimum fixing temperature was taken as the fixable range.

[0276] <Evaluation of heat-resistant storage stability of toner> 5.0 g of toner was placed in a 100 ml resin cup and left to stand at a temperature of 50° C. and a humidity of 10% RH for 10 days, after which the degree of cohesion of the toner was measured as follows. The measurement device used was a "Powder Tester" (Hosokawa Micron Corporation) with a digital display vibrometer "Digivro MODEL 1332A" (Showa Sokki Co., Ltd.) connected to the side of the vibration table. A sieve with a mesh size of 38 μm (400 mesh), a sieve with a mesh size of 75 μm (200 mesh), and a sieve with a mesh size of 150 μm (100 mesh) were placed on top of each other on the vibration table of the powder tester. Measurements were carried out in an environment of 23°C and 60% RH as follows.

[0277] (1) The vibration amplitude of the vibration table was adjusted in advance so that the displacement value on the digital display vibrometer would be 0.60 mm (peak-to-peak). (2) 5 g of the toner that had been left standing was precisely weighed and gently placed on the top sieve with 150 μm openings. (3) After the sieves were vibrated for 15 seconds, the mass of the toner remaining on each sieve was measured, and the degree of cohesion was calculated according to the following formula. Coagulation degree (%) = {(mass (g) of sample on a 150 μm sieve) / 5 (g)} x 100 + {(mass (g) of sample on a 75 μm sieve) / 5 (g)} x 100 x 0.6 + {(mass (g) of sample on a 38 μm sieve) / 5 (g)} x 100 x 0.2 The calculated degree of aggregation was used to evaluate the heat-resistant storage stability.

[0278] The results are shown in Table 13. For all of the toners of the examples, good results were obtained in terms of low-temperature fixability, hot offset resistance, and heat-resistant storage stability. On the other hand, for the toners of the comparative examples, sufficient low-temperature fixability was not obtained.

[0279] [Table 13]

[0280] <Evaluation of developing device> The developing devices of Examples 1 to 29 and Comparative Examples 1 to 7 were each evaluated as follows.

[0281] <Image evaluation> The image evaluation method will be explained below. The electrophotographic image forming apparatus used was a modified version of a commercially available laser printer, the LBP-7600C (manufactured by Canon Inc.). The configuration of the modified apparatus is shown in Figure 10. Modifications included connecting an external high-voltage power supply 20C in addition to power supplies 14C and 15C, allowing any potential difference to be set between the developing blade and the electrophotographic roller, and setting the output rate per unit time to 50 sheets per minute for A4 size paper in order to evaluate a high-speed process. The developing device in the process cartridge was also modified to use the combination of toner and developing roller shown in Table 12. The process cartridge used a commercially available toner cartridge 318 (black) (manufactured by Canon Inc.), and the developing roller was replaced with each developing roller to be evaluated. The product toner was also replaced with each toner to be evaluated. The toner loading amount was adjusted to 100 g. The product toner was removed from each of the yellow, cyan, and magenta stations, and the yellow, cyan, and magenta cartridges with their remaining toner detection mechanisms disabled were inserted for evaluation.

[0282] [Image fog evaluation] The prepared process cartridge was installed in the main body of an electrophotographic image forming apparatus and left in an environment of 30°C temperature and 80% relative humidity (HH) for 24 hours. Then, using an external high-voltage power supply, the potential difference between the development blade and the electrophotographic roller was set to -150V. In the same environment, images of a 4-point "E" letter were continuously printed on A4 evaluation paper (GF-C081, manufactured by Canon Inc.) with a print coverage of 2% of the A4 paper area. After printing 100 sheets, the apparatus was left for 24 hours. After leaving the apparatus for 24 hours, a solid white image was printed on the A4 evaluation paper according to the following evaluation method, and image fogging was evaluated.

[0283] Using a reflection densitometer (product name: TC-6DS / A, manufactured by Tokyo Denshoku Technology Center Co., Ltd.), the reflection density R1 of the recording material before image formation and the reflection density R2 of the recording material on which a solid white image was printed were measured, and the increase in reflection density (R2 - R1) was taken as the "fog value" of the image fog of the electrophotographic roller. The reflection density was measured over the entire image printing area of ​​the recording material, and the arithmetic mean value was used for the recording material before image formation, and the maximum value was used for the recording material on which a solid white image was printed.

[0284] [Image density stability evaluation] The prepared process cartridge was installed in the main body of an electrophotographic image forming apparatus and left for 24 hours in an environment (LL) at a temperature of 15°C and a relative humidity of 10%. Then, using an external high-voltage power supply, the potential difference between the developing blade and the electrophotographic roller was set to -300 V, and one solid black halftone image, 48 solid white images, and one solid black halftone image were printed in succession. The densities of the resulting halftone images on the first and 50th sheets were measured using a spectrodensitometer (product name: 508, manufactured by Xrite Corporation), and the density difference between the first and 50th sheets was determined. The smaller the density difference, the better. The evaluation results are shown in Table 14.

[0285] [Table 14]

[0286] Good development results were obtained with all of the toners of the examples. The toner of Comparative Example 1 gave good results in the development evaluation, but the low-temperature fixability was insufficient. In Comparative Examples 2 and 5, the electrical properties of the developing roller were more conductive than those of a conductor during the residence time between the regulating blade and the developing roller, so the toner charge leaked and image fogging occurred, resulting in unsatisfactory image quality. In Comparative Examples 3, 4, 6, and 7, the developing roller acted as a high dielectric, increasing the electrostatic adhesion between the toner and the developing roller. As a result, the amount of toner that could not be developed increased, and sufficient image density stability could not be obtained.

[0287] The present disclosure relates to the following configurations. (Configuration 1) A developing device having a developing roller and toner, the toner has toner particles containing a crystalline material; The resistivity of the toner at a frequency of 0.01 Hz obtained by AC impedance measurement is 2.00×10 14 Ω·m or less, the developing roller has a substrate having a conductive outer surface and a resin layer on the outer surface of the substrate, The frequency obtained by measuring the AC impedance of the developing roller is 1.0 x 10 2 Impedance Z in Hz is 1.00 x 10 4 is greater than or equal to Ω, The frequency obtained by measuring the AC impedance of the developing roller is 1.0 x 10 2 The phase θ1 of Hz is -40° to -10°, The frequency obtained by measuring the AC impedance of the developing roller is 1.0 x 10 4 The phase θ2 of Hz is -60° or less. A developing device characterized by: (Configuration 2) 2. The developing device according to claim 1, wherein the toner has an endothermic value of 20 to 70 J / g as measured by differential scanning calorimetry. (Configuration 3) the toner has an endothermic peak temperature of 40 to 75°C as measured by differential scanning calorimetry; 3. The developing device according to configuration 1 or 2, wherein the toner has an endothermic value of 20 to 70 J / g at 30 to 80° C. as determined by differential scanning calorimetry. (Configuration 4) 4. The developing device according to any one of configurations 1 to 3, wherein when a cross section of the toner is observed with a scanning transmission electron microscope, the area ratio of the crystalline material in the cross section of the toner is 30% or less. (Configuration 5) 5. The developing device according to any one of configurations 1 to 4, wherein the crystalline material contains at least one selected from the group consisting of a crystalline resin and an ester wax. (Configuration 6) the crystalline material contains an ester wax; the toner particles further contain an amorphous resin, when a cross section of the toner is observed with a scanning transmission electron microscope, the amorphous resin and the ester wax form a sea-island structure in the cross section of the toner; The developing device according to any one of configurations 1 to 5. (Configuration 7) the crystalline material contains a crystalline resin, the toner particles further contain an amorphous resin, The developing device according to any one of configurations 1 to 5. (Configuration 8) 8. The developing device according to claim 7, wherein the crystalline resin contains a monomer unit represented by the following formula (1): TIFF2026042381000020.tif52168 In formula (1), R 4 represents a hydrogen atom or a methyl group, and n represents an integer of 15 to 35. (Configuration 9) 9. The developing device according to claim 8, wherein the crystalline resin has a lactam structure. (Configuration 10) 10. The developing device according to claim 8 or 9, wherein the crystalline resin contains a monomer unit having a five-membered ring lactam structure. (Configuration 11) 11. The developing device according to any one of configurations 1 to 10, wherein when the outer surface of the developing roller is charged by a corona discharger and the potential of the outer surface is measured 0.06 seconds after the end of charging, the maximum value of the potential is less than 20.0 V. (Configuration 12) The developing roller, 1.0 × 10 -1 Hz to 1.0 x 10 6 12. The developing device according to any one of configurations 1 to 11, wherein the number of elementary processes obtained from AC impedance measurements up to 100 Hz is one. (Configuration 13) the developing roller has a conductive substrate and a resin layer on an outer peripheral surface of the substrate, 13. The developing device according to any one of configurations 1 to 12, wherein the resin layer contains conductive fine particles. (Configuration 14) When the arithmetic mean value of the circle-equivalent diameters of the conductive fine particles in the resin layer is Rc and the standard deviation of the circle-equivalent diameters is σc, Rc is 60 nm or less, 14. The developing device according to configuration 13, wherein σc / Rc is 0.00 to 0.65. (Configuration 15) When the arithmetic mean value of the distance between the wall surfaces of the conductive fine particles in the resin layer is d and the standard deviation of the distance between the wall surfaces is σd, d is 80 to 150 nm; 15. The developing device according to configuration 13 or 14, wherein σd / d is 0.00 to 0.60. (Configuration 16) 16. The developing device according to any one of Configurations 13 to 15, wherein the number average particle diameter of the primary particles of the conductive fine particles in the resin layer is 30 nm or less. (Configuration 17) 17. The developing device according to any one of Configurations 13 to 16, wherein the conductive fine particles are at least one selected from the group consisting of carbon black, indium-tin oxide, and antimony-titanium oxide. (Configuration 18) 18. The developing device according to any one of Configurations 13 to 17, wherein the resin layer further contains polyurethane. (Configuration 19) The polyurethane is selected from the group consisting of a polyether structure and a polycarbonate structure. 19. The developing device of claim 18, further comprising at least one developing unit. (Configuration 20) A process cartridge configured to be detachably mounted in a main body of an electrophotographic image forming apparatus, 20. A process cartridge comprising the developing device according to any one of configurations 1 to 19. (Configuration 21) An electrophotographic image forming apparatus, 20. An electrophotographic image forming apparatus comprising the developing device according to any one of Configurations 1 to 19.

Claims

1. A developing device having a developing roller and toner, the toner has toner particles containing a crystalline material; The resistivity of the toner at a frequency of 0.01 Hz obtained by AC impedance measurement is 2.00×10 １４ Ω m or less, the developing roller has a substrate having a conductive outer surface and a resin layer on the outer surface of the substrate, The frequency obtained by measuring the AC impedance of the developing roller is 1.0×10 ２ Impedance Z in Hz is 1.00 x 10 ４ is greater than or equal to Ω, The frequency obtained by measuring the AC impedance of the developing roller is 1.0×10 ２ The phase θ1 of Hz is −40° to −10°, The frequency obtained by measuring the AC impedance of the developing roller is 1.0×10 ４ The phase θ2 of Hz is −60° or less. A developing device characterized by:

2. 2. The developing device according to claim 1, wherein the toner has an endothermic amount of 20 to 70 J / g as measured by differential scanning calorimetry.

3. the toner has an endothermic peak temperature of 40 to 75°C as measured by differential scanning calorimetry; 2. The developing device according to claim 1, wherein the toner has an endothermic value of 20 to 70 J / g at 30 to 80° C. as measured by differential scanning calorimetry.

4. 2. The developing device according to claim 1, wherein when a cross section of the toner is observed with a scanning transmission electron microscope, the area ratio of the crystalline material in the cross section of the toner is 30% or less.

5. 2. The developing device according to claim 1, wherein the crystalline material contains at least one selected from the group consisting of a crystalline resin and an ester wax.

6. the crystalline material contains an ester wax; the toner particles further contain an amorphous resin, when a cross section of the toner is observed with a scanning transmission electron microscope, the amorphous resin and the ester wax form a sea-island structure in the cross section of the toner; The developing device according to claim 1 .

7. the crystalline material contains a crystalline resin, the toner particles further contain an amorphous resin, The developing device according to claim 1 .

8. 8. The developing device according to claim 7, wherein the crystalline resin contains a monomer unit represented by the following formula (1): In formula (1), R ４ represents a hydrogen atom or a methyl group, and n represents an integer of 15 to 35.

9. The developing device according to claim 8 , wherein the crystalline resin has a lactam structure.

10. 9. The developing device according to claim 8, wherein the crystalline resin contains a monomer unit having a five-membered ring lactam structure.

11. 2. The developing device according to claim 1, wherein when the outer surface of said developing roller is charged by a corona discharger and the potential of said outer surface is measured 0.06 seconds after the end of charging, the maximum value of said potential is less than 20.0 V.

12. 1.0×10 of the developing roller －１ Hz to 1.0 x 10 ６ 2. The developing device according to claim 1, wherein the number of elementary processes obtained from AC impedance measurements up to 100 Hz is one.

13. the developing roller has a conductive substrate and a resin layer on an outer peripheral surface of the substrate, 2. The developing device according to claim 1, wherein the resin layer contains conductive fine particles.

14. When the arithmetic mean value of the circle-equivalent diameters of the conductive fine particles in the resin layer is Rc and the standard deviation of the circle-equivalent diameters is σc, Rc is 60 nm or less, 14. The developing device according to claim 13, wherein σc / Rc is 0.00 to 0.

65.

15. When the arithmetic mean value of the distance between the wall surfaces of the conductive fine particles in the resin layer is d and the standard deviation of the distance between the wall surfaces is σd, d is 80 to 150 nm; 14. The developing device according to claim 13, wherein σd / d is 0.00 to 0.

60.

16. 14. The developing device according to claim 13, wherein the number average particle diameter of the primary particles of the conductive fine particles in the resin layer is 30 nm or less.

17. 14. The developing device according to claim 13, wherein the conductive fine particles are at least one selected from the group consisting of carbon black, indium-tin oxide, and antimony-titanium oxide.

18. The developing device according to claim 13 , wherein the resin layer further contains polyurethane.

19. 20. The developing device according to claim 18, wherein the polyurethane has at least one selected from the group consisting of a polyether structure and a polycarbonate structure.

20. A process cartridge configured to be detachably mounted in a main body of an electrophotographic image forming apparatus, A process cartridge comprising the developing device according to any one of claims 1 to 19.

21. An electrophotographic image forming apparatus, 20. An electrophotographic image forming apparatus comprising the developing device according to any one of claims 1 to 19.

Images