Resin particle, toner, and image forming apparatus

Abstract

To provide resin particles that well reproduce fine lines, provide high-quality images without image roughness, reduce the occurrence of passing of toner, and can maintain good cleanability over a long period.SOLUTION: Resin particles include at least a polyester resin as a binder resin. The volume average particle diameter of the resin particles is 4.5 μm or more and 6.0 μm or less. When the loose apparent density of the resin particles is defined as Y (g / cm3), and the circularity as X, the X and the Y satisfy the following relational expressions (1)-(3). The adhesive force of the resin particles is 150 gf or less. (1) 0.930≤X≤0.980, (2) Y<0.5, and (3) Y≥1.5X-1.04.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to resin particles, toner, and an image forming apparatus. [Background technology]

[0002] In recent years, toners with small particle diameters and nearly spherical shapes formed by polymerization methods or the like (hereinafter sometimes referred to as "polymerized toners") have been used to meet the demand for high image quality approaching that of offset printing. Polymerized toners have features such as higher transfer efficiency than conventional pulverized toners, making them capable of meeting the demand. However, polymerized toners are difficult to remove sufficiently from the surface of an image carrier using a cleaning blade, resulting in poor cleaning performance. This is because polymerized toners, with their small particle diameters and excellent sphericity, slip through the small gaps formed between the cleaning blade and the image carrier. Patent Document 1 discloses a toner that suppresses the occurrence of fogging and is resistant to pulverization even when stirred for a long period of time. Summary of the Invention [Problem to be solved by the invention]

[0003] The toner described in Patent Document 1 was insufficient to achieve both high image quality and cleaning properties. The present invention aims to provide resin particles that serve as base particles for toner, which have good reproducibility of fine lines, provide high-quality images without image shading, and are less likely to cause toner to slip through, and can maintain good cleaning properties for a long period of time. [Means for solving the problem]

[0004] The resin particles of the present invention, which are a means for solving the above problems, are as described below. Resin particles containing at least a polyester resin as a binder resin, The resin particles have a volume average particle size of 4.5 μm or more and 6.0 μm or less, The loose apparent density of the resin particles is defined as Y (g / cm 3 ) and the circularity is X, the X and the Y satisfy the following relational expressions (1) to (3), The resin particles have an adhesive strength of 150 gf or less. 0.930≦X≦0.980 (1) Y<0.5 (2) Y≧1.5X-1.04 (3) [Effects of the Invention]

[0005] The present invention makes it possible to provide high-quality images with good fine line reproducibility and no image blurring, and to provide resin particles that are less likely to slip through and can maintain good cleaning properties for a long period of time. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram showing an example of an image forming apparatus according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0007] The resin particles of the present invention are used as base particles for toner. For example, polymerized toner, which has a small particle size and a spherical shape, can produce high-quality images with good reproducibility of fine lines, but has a problem with cleaning properties. In the prior art described in Patent Document 1, the durability of the toner is improved by reducing the amount of toner particles of 5 μm or less and including a cyclic olefin copolymer, and the toner is prevented from being pulverized. However, the large particle size raises concerns about the reproducibility of fine lines. In order to improve the cleaning performance of small particle size toner, it is necessary to thoroughly remove the toner from the surface of the image carrier using a cleaning blade.

[0008] As a result of extensive research, the inventors have found that for small particle size toners with a volume average particle size of 4.5 μm or more and 6.0 μm or less, by controlling the circularity and loose apparent density within appropriate ranges, appropriate dam formation occurs not only in the external additives but also in the toner during cleaning, making it possible to improve cleaning performance. Furthermore, the volume average particle size is more preferably 4.6 μm or more and 5.6 μm or less.

[0009] The resin particles of the present invention do not contain magnetic particles, and therefore the toner having the resin particles of the present invention as base particles is a non-magnetic toner. Hereinafter, the "resin particles" may be referred to as "toner." In non-magnetic toner, the relationship between circularity and loose apparent density is usually expressed as follows: circularity is X, and the loose apparent density of the toner is Y (g / cm 3 ), the value of Y is generally lower than Y=1.5X-1.04, but the value of Y can be controlled by the BET, which is the shape and surface physical property of the toner. By making the loose apparent density Y higher than usual, it becomes possible to effectively form a dam on the cleaning blade. In the following, the unit of the numerical value indicating the loose apparent density is "g / cm 3 " However, the units are omitted.

[0010] If the loose apparent density is 0.5 or more, the toner dam layer becomes too large, increasing the load on the cleaning blade and causing the cleaning blade to turn over. If the loose apparent density is too small, the toner dam layer is not formed sufficiently, allowing the toner to slip through the small gap between the cleaning blade and the toner. If the toner has a low circularity, the toner does not roll easily, so a small dam layer is acceptable. However, if the toner has a high circularity, the toner easily slips through, so a large dam layer is required. The loose apparent density is more preferably 0.40 to 0.48, and even more preferably 0.42 to 0.45.

[0011] In addition, by keeping the toner adhesion force at 150 gf or less, it is possible to maintain an appropriate dam layer size, which also reduces excessive toner aggregation in terms of image quality and makes it possible to suppress image unevenness such as graininess. If the circularity of the toner is less than 0.930, the reproducibility of fine lines in the image deteriorates, and if the circularity exceeds 0.980, the cleaning ability deteriorates. When the polyester resin contains a large amount of polyester resin derived from an aliphatic monomer, blending PET is preferable because it increases the mechanical strength and makes the dam formation during cleaning stronger.

[0012] Furthermore, adding sulfonate groups to the binder resin improves the charging property, prevents toner aggregation, increases transfer efficiency, and is an effective means of suppressing the occurrence of blurred images. Furthermore, improving the viscoelasticity of the outermost surface also increases the mechanical strength, which is effective in forming dams during cleaning.

[0013] In order to produce a toner having a target circularity and loose apparent density, a production method including the steps of: preparing a solution in which a binder resin and a colorant are dissolved or dispersed in an organic solvent; adding water to the solution to invert the phase from a water-in-oil dispersion to an oil-in-water dispersion; and aggregating fine particles in the oil-in-water dispersion is effective as it makes it easier to control the shape.

[0014] The resin particles according to the present invention and the toner having the resin particles as base particles will be described below. The present invention is not limited to the following embodiments, and can be modified, added, modified, deleted, or otherwise altered within the scope of what a person skilled in the art can conceive. Any embodiment that achieves the functions and effects of the present invention is within the scope of the present invention.

[0015] <Resin particles> The resin particles of the present invention contain a polyester resin as a binder resin. The volume average particle size of the resin particles of the present invention is 4.5 μm or more and 6.0 μm or less, and the loose apparent density of the resin particles is Y (g / cm 3) and the circularity is X, the X and Y satisfy the following relational expressions (1) to (3), and the adhesive force of the resin particles is 150 gf or less. 0.930≦X≦0.980 (1) Y<0.5 (2) Y≧1.5X-1.04 (3)

[0016] The resin particles of the present invention can be produced by gradually adding components such as a resin and a colorant to an organic solvent while stirring, dissolving or dispersing them to prepare an oil phase, then adding an aqueous phase to this oil phase, and passing through a phase inversion emulsification process, a solvent removal process, an aggregation process, and a fusion process. The components used in this oil phase preparation step are described below.

[0017] <Amorphous polyester resin> The polyester resin is preferably an amorphous polyester resin, and more preferably a linear polyester resin, and more preferably an unmodified polyester resin. The unmodified polyester resin is a polyester resin obtained using a polyhydric alcohol and a polycarboxylic acid or a derivative thereof, such as a polycarboxylic acid, a polycarboxylic acid anhydride, or a polycarboxylic acid ester, and is not modified with an isocyanate compound or the like. The amorphous polyester resin preferably contains a dicarboxylic acid component as a constituent, and the dicarboxylic acid component preferably contains 50 mol % or more of terephthalic acid, which is advantageous in terms of heat-resistant storage stability.

[0018] Examples of the polyhydric alcohol include diols. Examples of the diol include alkylene (carbon number 2 to 3) oxide (average number of added moles 1 to 10) adducts of bisphenol A such as polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane and polyoxyethylene(2.2)-2,2-bis(4-hydroxyphenyl)propane; ethylene glycol, propylene glycol; hydrogenated bisphenol A, and alkylene (carbon number 2 to 3) oxide (average number of added moles 1 to 10) adducts of hydrogenated bisphenol A. These may be used alone or in combination of two or more.

[0019] Examples of the polycarboxylic acid include dicarboxylic acids. Examples of the dicarboxylic acid include adipic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid; and succinic acids substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, such as dodecenylsuccinic acid and octylsuccinic acid. These may be used alone or in combination of two or more. Furthermore, for the purpose of adjusting the acid value and hydroxyl value, the amorphous polyester resin may contain at least one of a trivalent or higher carboxylic acid and a trivalent or higher alcohol at the end of the resin chain.

[0020] Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, and acid anhydrides thereof. Examples of the trihydric or higher alcohol include glycerin, pentaerythritol, and trimethylolpropane.

[0021] The molecular weight of the amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose. As measured by GPC (gel permeation chromatography), the weight average molecular weight (Mw) is preferably 3,000 to 10,000. The number average molecular weight (Mn) is preferably 1,000 to 4,000. The Mw / Mn ratio is preferably 1.0 to 4.0. When the molecular weight is equal to or greater than the lower limit, it is possible to prevent the toner from having a deterioration in heat-resistant storage stability and durability against stress such as stirring in a developing machine, etc. When the molecular weight is equal to or less than the upper limit, it is possible to prevent the toner from having an increase in viscoelasticity when melted, and to prevent the toner from having a deterioration in low-temperature fixability. The weight average molecular weight (Mw) is more preferably 4,000 to 7,000. The number average molecular weight (Mn) is more preferably 1,500 to 3,000. The Mw / Mn ratio is more preferably 1.0 to 3.5.

[0022] The acid value of the amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose. It is preferably 1 mgKOH / g or more and 50 mgKOH / g or less, and more preferably 5 mgKOH / g or more and 30 mgKOH / g or less. When the acid value is 1 mgKOH / g or more, the toner tends to be negatively charged, and further, when fixed to paper, the affinity between the paper and the toner is improved, thereby improving low-temperature fixability. When the acid value is 50 mgKOH / g or less, it is possible to suppress a decrease in charging stability, particularly charging stability against environmental fluctuations.

[0023] The hydroxyl value of the amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 mgKOH / g or more. The glass transition temperature (Tg) of the amorphous polyester resin is preferably 40° C. or higher and 80° C. or lower, more preferably 50° C. or higher and 70° C. or lower. When the glass transition temperature is 40° C. or higher, the toner has sufficient heat-resistant storage stability and durability against stress such as stirring in a developing machine, and also has good filming resistance. When the glass transition temperature is 80° C. or lower, the toner is sufficiently resistant to deformation due to heat and pressure during fixing, and has good low-temperature fixability.

[0024] The molecular structure of the amorphous polyester resin can be confirmed by NMR measurement using a solution or a solid, as well as by X-ray diffraction, GC / MS, LC / MS, IR measurement, etc. -1 and 990±10cm -1 One example is a method for detecting amorphous polyester resins that do not have absorption due to δCH (out-of-plane bending vibration) of olefins.

[0025] The content of the amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 50 to 90 parts by mass, more preferably 60 to 80 parts by mass, relative to 100 parts by mass of the toner. When the content is 50 parts by mass or more, deterioration of the dispersibility of the pigment and release agent in the toner can be suppressed, and the occurrence of fogging and distortion of the image can be suppressed.

[0026] <Repeating units derived from polyethylene terephthalate (PET)> In addition to the above components, the polyester resin of the present invention may contain repeating units derived from so-called polyethylene terephthalate (PET), which is a condensate of terephthalic acid and ethylene glycol. In this specification, "repeating units derived from polyethylene terephthalate (PET)" may also be referred to as "PET repeating units."

[0027] The polyester resin containing the PET repeating unit is suitable for use because of its excellent mechanical durability. Furthermore, from the viewpoint of reducing the environmental impact, such as reducing the consumption of petroleum resources, it is preferable to use recycled PET as the raw material. The polyester resin containing the PET repeating unit can be obtained by polycondensation with the above-mentioned polyester resin material while causing an ester exchange reaction.

[0028] (crystalline resin) It is preferable to add a crystalline resin to the toner of the present invention in order to improve low-temperature fixability. The crystalline resin is not particularly limited as long as it has crystallinity and can be appropriately selected depending on the purpose. Examples include polyester resin, polyurethane resin, polyurea resin, polyamide resin, polyether resin, vinyl resin, modified crystalline resin, etc. These may be used alone or in combination of two or more.

[0029] (crystalline polyester resin) The crystalline polyester resin will be described below. The crystalline polyester resin (hereinafter, sometimes referred to as "crystalline polyester resin C") has high crystallinity and therefore exhibits heat melting properties that show a sudden change in viscosity near the fixing start temperature. By using the crystalline polyester resin C having such properties together with the amorphous polyester resin, a toner having both good heat-resistant storage stability and low-temperature fixability can be obtained. For example, when used together, the heat-resistant storage stability is good due to the crystallinity up to just before the melting start temperature, and at the melting start temperature, the crystalline polyester resin C melts, causing a sudden decrease in viscosity (sharp melt property), which in turn causes it to become compatible with the amorphous polyester resin B described above, and both resins rapidly decrease in viscosity, allowing for good fixation.

[0030] Crystalline polyester resins are obtained from polyhydric alcohols and polycarboxylic acids such as polycarboxylic acids, polycarboxylic anhydrides, and polycarboxylic esters, or derivatives thereof. Note that, in the present invention, the crystalline polyester resin refers to a resin obtained using a polyhydric alcohol and a polycarboxylic acid such as polycarboxylic acids, polycarboxylic anhydrides, and polycarboxylic esters, or derivatives thereof, as described above, and modified polyester resins, such as prepolymers and resins obtained by subjecting the prepolymers to crosslinking and / or elongation reactions, do not fall under the category of crystalline polyester resins.

[0031] <<Polyhydric alcohol>> The polyhydric alcohol is not particularly limited and can be appropriately selected depending on the purpose. Examples include diols and trihydric or higher alcohols. Examples of the diol include saturated aliphatic diols. Examples of the saturated aliphatic diol include linear saturated aliphatic diols and branched saturated aliphatic diols. Among these, linear saturated aliphatic diols are preferred, and linear saturated aliphatic diols having 2 to 12 carbon atoms are more preferred. If the saturated aliphatic diol is branched, the crystallinity of the crystalline polyester resin may decrease, resulting in a lower melting point. Furthermore, if the saturated aliphatic diol has more than 12 carbon atoms, it may be difficult to obtain a practical material.

[0032] Examples of the saturated aliphatic diol include ethylene glycol, 1,3-propanediol, 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, etc. Among these, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol are preferred in terms of the high crystallinity and excellent sharp melt properties of the crystalline polyester resin. Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc. These may be used alone or in combination of two or more.

[0033] <<Polycarboxylic Acids>> The polycarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples include dicarboxylic acids and tricarboxylic or higher carboxylic acids. Examples of the dicarboxylic acid include saturated aliphatic dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid; and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, and mesaconic acid. Further examples include anhydrides of these compounds and lower (C1 to C3) alkyl esters of these compounds. Among these, plant-derived saturated aliphatic fatty acids having 12 or less carbon atoms are preferred from the viewpoint of carbon neutrality. Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc., as well as anhydrides thereof and lower (C1 to C3) alkyl esters thereof, etc. These may be used alone or in combination of two or more.

[0034] The crystalline polyester resin is preferably composed of a linear saturated aliphatic dicarboxylic acid having 4 to 12 carbon atoms and a linear saturated aliphatic diol having 2 to 12 carbon atoms, which results in high crystallinity and excellent sharp melting properties, allowing the resin to exhibit excellent low-temperature fixability. Another method for controlling the crystallinity and softening point of a crystalline polyester resin is to design and use a non-linear polyester obtained by condensation polymerization of a trivalent or higher polyhydric alcohol such as glycerin as the alcohol component or a trivalent or higher polycarboxylic acid such as trimellitic anhydride as the acid component during polyester synthesis.

[0035] The molecular structure of the crystalline polyester resin of the present invention can be confirmed by NMR measurement of a solution or a solid, as well as X-ray diffraction, GC / MS, LC / MS, IR measurement, etc., but it can be easily confirmed by infrared absorption spectroscopy at 965±10 cm -1 Or 990±10cm -1 Examples include those that have absorption based on the δCH (out-of-plane bending vibration) of olefins.

[0036] Regarding molecular weight, from the viewpoint that a narrow molecular weight distribution and a low molecular weight provide excellent low-temperature fixability, while a high content of low-molecular weight components deteriorates heat-resistant storage stability, extensive research has revealed that, in a molecular weight distribution diagram by GPC of the o-dichlorobenzene soluble fraction, the horizontal axis is log(M) and the vertical axis is weight %, the peak position is in the range of 3.5 to 4.0, the half-width of the peak is 1.5 or less, the weight-average molecular weight (Mw) is 3,000 to 30,000, the number-average molecular weight (Mn) is 1,000 to 10,000, and the Mw / Mn is 1 to 10. Furthermore, the weight-average molecular weight (Mw) is 5,000 to 15,000, the number-average molecular weight (Mn) is 2,000 to 10,000, and the Mw / Mn is 1 to 5.

[0037] From the viewpoint of affinity between paper and resin, the acid value of the crystalline polyester resin is preferably 5 mgKOH / g or more to achieve the desired low-temperature fixability, and more preferably 7 mgKOH / g or more to prepare fine particles by phase inversion emulsification, while 45 mgKOH / g or less is preferred to improve hot offset resistance. Furthermore, the hydroxyl value of the crystalline polymer is preferably 0 mgKOH / g or more and 50 mgKOH / g or less, more preferably 5 mgKOH / g or more and 50 mgKOH / g or less, to achieve the desired low-temperature fixability and good charging characteristics.

[0038] (coloring agent) Known dyes and pigments can be used as colorants in the present invention, such as carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ochre, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Balkan fast yellow (5G, R), tartrazine lake, quinoline yellow lake, anthrazan yellow BGL, isoi Indrinone Yellow, Bengala, Red Lead, Cinnabar, Cadmium Red, Cadmium Mercury Red, Antimony Vermilion, Permanent Red 4R, Para Red, Faise Red, Parachlor Orthonitroaniline Red, Lithol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Kanmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Lithol Rubin GX, Permanent Red F5R, Brilliant Tocarmine 6B, Pogment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal-free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine, Prussian Blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Chromium Oxide, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake,Malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc oxide, lithopone, and mixtures thereof can be used.

[0039] (organic solvent) The organic solvent is preferably volatile with a boiling point of less than 100° C., since this facilitates subsequent removal of the organic solvent. Examples of such organic solvents that can be used include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, and isopropyl alcohol, which can be used alone or in combination. When the resin to be dissolved or dispersed in the organic solvent is a resin having a polyester skeleton, it is preferable to use an ester-based solvent such as methyl acetate, ethyl acetate, or butyl acetate, or a ketone-based solvent such as methyl ethyl ketone or methyl isobutyl ketone, as these solvents have high solubility. Among these, methyl acetate, ethyl acetate, and methyl ethyl ketone, which have high solvent removability, are particularly preferred.

[0040] (prepolymer) The oil phase in the process for producing the resin particles of the present invention may contain a prepolymer. The prepolymer is subjected to suspension polymerization to produce a polyester resin (referred to as "Polyester Resin D"). The reactive precursor may be a polyester having a group capable of reacting with an active hydrogen group. Examples of the group capable of reacting with an active hydrogen group include an isocyanate group, an epoxy group, a carboxylic acid, and an acid chloride group. Among these, an isocyanate group is preferred because it can introduce a urethane bond or a urea bond into the amorphous polyester resin. The reactive precursor may have a branched structure imparted by at least one of a trivalent or higher alcohol and a trivalent or higher carboxylic acid.

[0041] Examples of the polyester resin containing an isocyanate group include a reaction product of a polyester resin having an active hydrogen group with a polyisocyanate. The polyester resin having an active hydrogen group can be obtained, for example, by polycondensation of a diol, a dicarboxylic acid, and at least one of a trivalent or higher alcohol and a trivalent or higher carboxylic acid. The trivalent or higher alcohol and the trivalent or higher carboxylic acid impart a branched structure to the polyester resin containing an isocyanate group.

[0042] Examples of the diol include aliphatic diols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and 1,12-dodecanediol; diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylolpropanediol; Examples of suitable diols include diols having an oxyalkylene group such as ethylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A; alicyclic diols to which alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide have been added; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; and alkylene oxide adducts of bisphenols, such as bisphenols to which alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide have been added. Among these, from the viewpoint of controlling the glass transition temperature of the polyester resin D to 20° C. or lower, it is preferable to use aliphatic diols having 3 to 10 carbon atoms, such as 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, and 3-methyl-1,5-pentanediol, and it is more preferable to use 50 mol% or more of the alcohol component in the resin. These diols may be used alone or in combination of two or more.

[0043] The polyester resin obtained by elongating the prepolymer is preferably the amorphous polyester resin, and by providing steric hindrance to the resin chain, the melt viscosity during fixing is reduced, making it easier to achieve low-temperature fixability. For this reason, the main chain of the aliphatic diol preferably has a structure represented by the following general formula (1): [ka] [In the formula, R1 and R2 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an odd number from 3 to 9. However, in the n repeating units, R1 and R2 may be the same or different.]

[0044] Here, the main chain of the aliphatic diol in the present invention refers to the carbon chain that connects two hydroxyl groups of the aliphatic diol with the shortest number of carbon atoms. The main chain preferably has an odd number of carbon atoms, since the odd-even nature of the main chain reduces crystallinity. Furthermore, the main chain preferably has at least one alkyl group having 1 to 3 carbon atoms in the side chain, since the interaction energy between the main chain molecules is reduced due to the stericity.

[0045] Examples of the dicarboxylic acid include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, dodecanedioic acid, maleic acid, and fumaric acid; and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. Furthermore, anhydrides, lower (C1 to C3) alkyl esters, and halides of these may also be used. Among these, from the viewpoint of controlling the Tg of the polyester resin D to 20°C or less, aliphatic dicarboxylic acids having from 4 to 12 carbon atoms are preferred, and it is more preferred to use them in an amount of 50% by mass or more of the carboxylic acid components in the resin. These dicarboxylic acids may be used alone or in combination of two or more.

[0046] Examples of the trihydric or higher alcohols include trihydric or higher aliphatic alcohols such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and sorbitol; trihydric or higher polyphenols such as trisphenol PA, phenol novolac, and cresol novolac; and alkylene oxide adducts of trihydric or higher polyphenols, such as those obtained by adding alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to trihydric or higher polyphenols.

[0047] Examples of the trivalent or higher carboxylic acid include trivalent or higher aromatic carboxylic acids, and particularly preferred are trivalent or higher aromatic carboxylic acids having 9 to 20 carbon atoms, such as trimellitic acid and pyromellitic acid. Furthermore, anhydrides, lower (1 to 3 carbon atoms) alkyl esters, and halides of these may also be used.

[0048] Examples of the polyisocyanate include diisocyanates and tri- or higher valent isocyanates. The polyisocyanate is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include 1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), crude MDI [crude diaminophenylmethane [condensation product of formaldehyde and aromatic amine (aniline) or a mixture thereof; diaminodiphenylmethane and a small amount (for example, 5 to 20% by mass) of a trifunctional or more functional group], Phosgenates of the above polyamines and their mixtures: polyallyl polyisocyanate (PAPI), aromatic diisocyanates such as 1,5-naphthylene diisocyanate, 4,4',4"-triphenylmethane triisocyanate, m- and p-isocyanatophenylsulfonyl isocyanate; ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, Aliphatic diisocyanates such as isocyanates, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate; isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis(2-isocyanato Examples of the diisocyanate include alicyclic diisocyanates such as m- and p-xylylene diisocyanate (XDI) and α,α,α',α'-tetramethylxylylene diisocyanate (TMXDI); trivalent or higher polyisocyanates such as lysine triisocyanate and diisocyanate-modified products of trivalent or higher alcohols; and modified products of these isocyanates, and mixtures of two or more of these may also be used.Examples of the modified isocyanate include modified products containing a urethane group, a carbodiimide group, an allophanate group, a urea group, a biuret group, a uretdione group, a uretoimine group, an isocyanurate group, and an oxazolidone group.

[0049] <Core-shell structure> The resin particles have a core-shell structure consisting of a core layer and a shell layer. The shell resin constituting the shell layer is preferably amorphous polyester resin A described below, and the amorphous polyester resin contained in the core is preferably amorphous polyester resin B described below.

[0050] In this specification, "having a core-shell structure" means a structure having a core layer and a shell layer, "shell layer" means a layer made of a resin present in the outermost layer of the resin particle, and "core layer" means a region within the resin particle excluding the shell layer. The core layer and the shell layer are not completely compatible with each other and are formed heterogeneously. In the core-shell structure, the surface of the core layer is preferably covered with the shell layer.

[0051] In the core-shell structure, the surface of the core layer may be completely covered with the shell layer, or may not be completely covered with the shell layer. Examples of a form in which the surface of the core layer is not completely covered with the shell layer include a form in which the core layer is covered with the shell layer in a mesh-like pattern, and a form in which the core layer is partially exposed from the shell layer. Among these, from the viewpoint of heat-resistant storage stability, it is preferable that the surface of the core layer is completely covered with the shell layer.

[0052] In one embodiment of the resin particles of the present invention, the resin particles contain an amorphous polyester resin as a binder resin, form a core-shell structure, and the shell layer contains a polyester resin containing at least a sulfonate group. The resin particles of the present invention have a core-shell structure consisting of a core layer and a shell layer, thereby ensuring heat-resistant storage stability.

[0053] By using a polyester resin containing sulfonate groups for the shell layer, high charging performance can be achieved due to the charging effect of the sulfonate groups. In addition, the viscoelasticity of the sulfonate groups can be used to supplement the strength of the toner, enabling low-temperature fixability and storage stability to be achieved while maintaining high carbon neutrality.

[0054] (Sulfonate group-containing polyester resin) The alcohol and carboxylic acid used in the synthesis of the sulfonate group-containing polyester resin are not particularly limited, and examples of the constituent components include the polyhydric alcohols and polyhydric carboxylic acids exemplified in the section on the amorphous polyester resin.

[0055] (Sulfonic acid-containing monomer) The sulfonate group-containing polyester resin is synthesized using a monomer containing a sulfonate group. Examples of the sulfonate group-containing monomer include aromatic sulfonate group-containing monomers and aliphatic sulfonate group-containing monomers. Among these, aromatic sulfonate group-containing monomers having a divalent or higher carboxylic acid are preferred.

[0056] Examples of aromatic dicarboxylic acids having a sulfonate group include sulfonates of 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfo-2,6-naphthalenedicarboxylic acid, and ester-forming derivatives thereof [lower alkyl (C1-4) esters (methyl esters, ethyl esters, etc.), acid anhydrides, etc.]. Examples of aliphatic dicarboxylic acids having a sulfo group include sulfonates of sulfosuccinic acid and its ester-forming derivatives [lower alkyl (C1-4) esters (methyl ester, ethyl ester, etc.), acid anhydrides, etc.].

[0057] Examples of sulfonates include salts of alkali metals (lithium, sodium, potassium, etc.), salts of alkaline earth metals (magnesium, calcium, etc.), ammonium salts, amine salts such as mono-, di-, and tri-amines having a hydroxyalkyl (C2-4) group (organic amine salts such as mono-, di-, and tri-ethylamine, mono-, di-, and tri-ethanolamine, diethylethanolamine, etc.), quaternary ammonium salts of these amines, and combinations of two or more of these. Among these, 5-sulfoisophthalic acid salts are preferred, and 5-sulfoisophthalic acid sodium salt and 5-sulfoisophthalic acid potassium salt are particularly preferred.

[0058] A charge control agent or the like may be added to the oil phase. (Charge control agent) Any known charge control agent can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxyamines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus simple substance or compounds, tungsten simple substance or compounds, fluorine-based activators, metal salicylate, and metal salts of salicylic acid derivatives. Specifically, these include the nigrosine dye Bontron 03, the quaternary ammonium salt Bontron P-51, the metal-containing azo dye Bontron S-34, the oxynaphthoic acid metal complex E-82, the salicylic acid metal complex E-84, and the phenol condensate E-89 (all manufactured by Orient Chemical Industry Co., Ltd.), the quaternary ammonium salt molybdenum complexes TP-302 and TP-415 (both manufactured by Hodogaya Chemical Co., Ltd.), the quaternary ammonium salt Copy Charge PSY VP2038, the triphenylmethane derivative Copy Blue PR, and the quaternary ammonium salt Copy Charge NEG VP2036 and Copy Charge NX. Examples of suitable charge control agents include VP434 (manufactured by Hoechst), LRA-901, the boron complex LR-147 (manufactured by Nippon Carlit), copper phthalocyanine, perylene, quinacridone, azo pigments, and other polymeric compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts. The charge control agent may be used in an amount that allows the agent to exhibit its performance without interfering with fixability, etc., and is contained in the toner in an amount of 0.5 to 5% by mass, and preferably 0.8 to 3% by mass.

[0059] (mold release agent) The release agent is not particularly limited and can be selected appropriately depending on the purpose, but a release agent with a low melting point of 50° C. to 120° C. is preferred. The low-melting release agent, when dispersed in the resin, acts effectively between the fixing roller and the toner interface, thereby improving hot offset resistance even in an oil-less case (where no release agent such as oil is applied to the fixing roller).

[0060] Suitable examples of release agents include waxes. Examples of waxes include natural waxes such as plant-based waxes (e.g., carnauba wax, cotton wax, Japan wax, and rice wax); animal-based waxes (e.g., beeswax and lanolin); mineral waxes (e.g., ozokerite and ceresin); and petroleum waxes (e.g., paraffin, microcrystalline wax, and petrolatum). In addition to these natural waxes, synthetic hydrocarbon waxes (e.g., Fischer-Tropsch wax and polyethylene wax); synthetic waxes (e.g., esters, ketones, and ethers); and other synthetic waxes. Other examples include fatty acid amides (e.g., 12-hydroxystearic acid amide, stearic acid amide, phthalimide anhydride, and chlorinated hydrocarbons); low-molecular-weight crystalline polymer resins such as polyacrylate homopolymers and copolymers (e.g., n-stearyl acrylate-ethyl methacrylate copolymers); and crystalline polymers having long alkyl groups in their side chains. These may be used alone or in combination of two or more.

[0061] The melt viscosity of the wax, as measured at a temperature 20°C higher than the melting point of the wax, is preferably 5 cps to 1,000 cps, and more preferably 10 cps to 100 cps. A melt viscosity of 5 cps or higher can prevent a decrease in releasability, while a melt viscosity of 1,000 cps or lower can sufficiently exhibit the effects of hot offset resistance and low-temperature fixability. The content of the wax in the toner is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0% by mass to 40% by mass, and more preferably 3% by mass to 30% by mass.

[0062] <Method of manufacturing resin particles> The resin particles are preferably granulated in an aqueous medium. Methods for granulating in an aqueous medium include suspension polymerization, emulsion polymerization aggregation, phase inversion emulsion aggregation, and dissolution suspension methods, with the phase inversion emulsion aggregation method being preferred. A method for producing resin particles according to an embodiment will be described. The method for producing resin particles according to an embodiment includes an oil phase preparation step, an aqueous phase preparation step, a phase inversion emulsification step, a solvent removal step, an aggregation step, and a fusion step, and may further include other steps such as a shell formation step, a washing step, a drying step, an annealing step, and an external addition step, as necessary.

[0063] (Oil phase preparation process) In the oil phase preparation step, the raw materials of the toner, such as a resin (amorphous polyester resin, crystalline polyester resin, etc.), and, if necessary, materials such as a colorant, a prepolymer, and a wax are first dissolved or dispersed in an organic solvent to prepare the oil phase. Note that some of the materials may be added in the aggregation step described below. The method for preparing the oil phase is not particularly limited and can be appropriately selected depending on the purpose. For example, a method in which raw materials such as a resin are gradually added to an organic solvent while stirring, and dissolved or dispersed therein, can be mentioned. For dispersion, known dispersing machines such as a bead mill and a disk mill can be used.

[0064] The raw materials used in the oil phase preparation step can be those described above in the description of the components used in the oil phase preparation step. These may be used alone or in combination of two or more. The organic solvent is not particularly limited and can be appropriately selected depending on the purpose, but a volatile solvent with a boiling point of less than 100° C. is preferred because it makes it easier to remove the organic solvent later. Examples of such organic solvents include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, and isopropyl alcohol. These may be used alone or in combination of two or more.

[0065] When the resin to be dissolved or dispersed in an organic solvent is a resin having a polyester skeleton, the organic solvent is preferably an ester solvent such as methyl acetate, ethyl acetate, or butyl acetate, or a ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone, because of its high solubility. Among these, methyl acetate, ethyl acetate, or methyl ethyl ketone is preferred as the organic solvent, because of its high solvent removability.

[0066] The amount of organic solvent used is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 40 parts by mass or more and 300 parts by mass or less, more preferably 60 parts by mass or more and 140 parts by mass or less, and even more preferably 80 parts by mass or more and 120 parts by mass or less, per 100 parts by mass of the raw material for the resin particles.

[0067] (Aqueous phase preparation process) In the aqueous phase preparation step, an aqueous phase (aqueous medium) is prepared. The aqueous medium is not particularly limited and can be appropriately selected from known ones, and examples thereof include water, a solvent miscible with water, and a mixture thereof. From the viewpoint of granulation properties, the concentration of the organic solvent is preferably equal to or less than the saturation concentration in ion-exchanged water. The water-miscible solvent is not particularly limited and can be appropriately selected from known solvents, such as alcohol, dimethylformamide, tetrahydrofuran, cellosolves, lower ketones, and esters. Examples of alcohols include methanol, isopropanol, and ethylene glycol. Examples of lower ketones include acetone and methyl ethyl ketone. An example of the esters is ethyl acetate. These may be used alone or in combination of two or more.

[0068] (Phase inversion emulsification process) In the phase inversion emulsification step, the oil phase obtained in the oil phase preparation step is atomized. After neutralizing the oil phase, ion-exchanged water is added to the neutralized oil phase, and a microparticle dispersion is obtained by phase inversion emulsification, which inverts the water-in-oil dispersion into an oil-in-water dispersion. The phase inversion emulsification is carried out by uniformly mixing and dispersing the ingredients using a conventional stirrer or dispersing device. The stirring blade is not particularly limited and can be appropriately selected depending on the viscosity of the solution. Examples include low-viscosity stirring blades such as paddles and propellers, medium-viscosity stirring blades such as anchors and maxblends, and high-viscosity stirring blades such as helical ribbons. The dispersion device is not particularly limited and examples include ultrasonic dispersers, bead mills, ball mills, roll mills, homomixers, ultramixers, disperser mixers, penetrating-type high-pressure dispersion devices, collision-type high-pressure dispersion devices, porous high-pressure dispersion devices, ultrahigh-pressure homogenizers, and ultrasonic homogenizers. A conventional stirrer and dispersion device may be used in combination. Among these, paddle and anchor are preferred in that they can control the volume average particle size of the dispersion (oil droplets) within the above-mentioned preferred range.

[0069] The base used to neutralize the oil phase may be either a basic inorganic compound or a basic organic compound. Examples of basic inorganic compounds include sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, and ammonia. Examples of basic organic compounds include N,N-dimethylethanolamine, N,N-diethylethanolamine, triethanolamine, tripropanolamine, tributanolamine, triethylamine, n-propylamine, n-butylamine, isopropylamine, monomethanolamine, morpholine, methoxypropylamine, pyridine, vinylpyridine, and isophoronediamine.

[0070] When using a stirring blade, the conditions such as the rotation speed, stirring time, and stirring temperature are not particularly limited and can be appropriately selected depending on the purpose. The rotation speed is not particularly limited, but is preferably 100 rpm to 1,000 rpm, and more preferably 200 rpm to 600 rpm. The stirring time and stirring temperature are not particularly limited and may be appropriately selected depending on the purpose.

[0071] A dispersant may also be used if necessary. The dispersant is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include surfactants, poorly water-soluble inorganic compound dispersants, and polymeric protective colloids. These may be used alone or in combination of two or more. Among these, surfactants are preferred. The surfactant is not particularly limited and can be appropriately selected depending on the purpose. For example, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc. can be used. The anionic surfactant is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, etc. Among these, those having a fluoroalkyl group are preferred.

[0072] (solvent removal) In order to remove the organic solvent from the obtained colored fine particle dispersion, a method can be employed in which the temperature of the entire system is gradually increased while being stirred, and the organic solvent in the droplets is completely evaporated and removed. Alternatively, the obtained colored particle dispersion can be sprayed into a dry atmosphere while stirring to completely remove the organic solvent from the droplets. Alternatively, the colored particle dispersion can be stirred while reducing the pressure to evaporate and remove the organic solvent. The latter two methods can be used in combination with the first method. The drying atmosphere in which the colored fine particle dispersion is sprayed is generally a gas such as air, nitrogen, carbon dioxide, or a heated combustion gas, particularly a gas stream heated to a temperature equal to or higher than the boiling point of the highest boiling point solvent used. The desired quality can be obtained sufficiently by short-term treatment using a spray dryer, belt dryer, rotary kiln, or the like. By the above method, a colored particle dispersion can be obtained.

[0073] (Agglutination process) Next, the obtained colored fine particle dispersion is agglomerated while being stirred until the particles reach a desired particle size. To achieve flocculation, existing methods can be used, such as adding a flocculant or adjusting the pH. When adding a flocculant, it can be added directly, but it is preferable to use an aqueous solution of the flocculant, as this can prevent localized high concentrations. It is also preferable to gradually add the flocculating salt while monitoring the particle size of the colored particles. The temperature of the dispersion during aggregation is preferably near the Tg of the resin used. If the liquid temperature is too low, aggregation does not proceed very well, resulting in poor efficiency, while if the liquid temperature is too high, the aggregation rate increases, resulting in the generation of coarse particles and a deterioration in particle size distribution. When the target particle size is reached, aggregation is stopped by adding a salt or chelating agent with a low ionic valence, adjusting the pH, lowering the temperature of the dispersion, or adding a large amount of aqueous medium to dilute the concentration. By the above method, a dispersion of colored aggregated particles can be obtained. In the aggregation step, a release agent or a crystalline polyester resin may be added. In this case, the material to be added is mixed with a dispersion liquid in which the material is dispersed in an aqueous medium or the colored fine particle dispersion liquid, and then the material is aggregated to obtain aggregated particles in which the release agent or the crystalline resin is uniformly dispersed.

[0074] (flocculant) Known flocculants can be used, such as metal salts of monovalent metals such as sodium and potassium, metal salts of divalent metals such as calcium and magnesium, and metal salts of trivalent metals such as iron and aluminum.

[0075] (fusion process) The resulting aggregated particles are then fused by heat treatment to reduce irregularities and to form spherical particles. Fusion can be achieved by heating the dispersion of the colored aggregated particles while stirring. The temperature of the dispersion is preferably near a temperature above the Tg of the resin used.

[0076] (Shelling process) If necessary, a shelling step may be carried out in which a shell layer is formed on the particles obtained in the aggregation step. The method for forming the shell layer is not particularly limited and can be appropriately selected depending on the purpose. For example, the method for forming the shell layer includes a method in which spherical particles having a desired particle size are produced in an aggregation step, an amorphous resin is added, and the aggregation step and the fusion step are repeated to form the shell layer.

[0077] (Washing and drying process) The toner particle dispersion obtained by the above method contains not only toner particles but also secondary materials such as coagulating salts, so washing is performed to extract only the toner particles from the dispersion. Methods for washing toner particles include centrifugation, vacuum filtration, and filter press, but the method is not particularly limited in the present invention. While any of these methods produces a cake of toner particles, if the toner particles cannot be sufficiently washed in one operation, the resulting cake may be dispersed again in an aqueous solvent to form a slurry, and the process of extracting the toner particles by one of the above methods may be repeated. Alternatively, if washing is performed by vacuum filtration or filter press, a method may be used in which the aqueous solvent is passed through the cake to wash away the secondary materials absorbed by the colored resin particles. The aqueous solvent used for this washing is water or a mixed solvent of water and an alcohol such as methanol or ethanol. However, considering the cost and the environmental impact of wastewater treatment, water is preferred.

[0078] Since the washed toner particles contain a large amount of aqueous medium, they can be dried to remove the aqueous medium and obtain only the toner particles. Drying methods that can be used include dryers such as spray dryers, vacuum freeze dryers, reduced-pressure dryers, stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers, and agitator dryers. It is preferable to dry the dried toner particles until the moisture content is less than 1%. If the colored resin particles after drying are soft and agglomerated, which can cause inconvenience during use, they may be crushed using a device such as a jet mill, Henschel mixer, super mixer, coffee mill, Oster blender, or food processor to loosen the agglomerates.

[0079] (Annealing process) When a crystalline resin is added, annealing the toner after drying causes phase separation between the amorphous and crystalline resins, improving fixability. Specifically, this can be achieved by storing the toner at a temperature near its Tg for 10 hours or more.

[0080] (External addition process) Toner particles obtained in the present invention may be added or mixed with inorganic fine particles, polymeric fine particles, cleaning aids, etc. in order to provide them with fluidity, chargeability, cleaning properties, etc. Specific mixing methods include applying an impact force to the mixture with blades rotating at high speed, or throwing the mixture into a high-speed air current, accelerating it, and causing the particles or composite particles to collide with an appropriate collision plate. Examples of equipment include an Ang Mill (manufactured by Hosokawa Micron Corporation), a modified I-type Mill (manufactured by Nippon Pneumatic Co., Ltd.) with reduced grinding air pressure, a Hybridization System (manufactured by Nara Machinery Works), a Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), and an automatic mortar.

[0081] (external additives) The primary particle diameter of the inorganic fine particles is preferably 5 nm to 2 μm, and more preferably 5 nm or more and 500 nm or less. 2 / g or more 500m 2 / g or less. The proportion of these inorganic fine particles used is preferably 0.01% by mass or more and 5% by mass or less of the toner. Specific examples of inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

[0082] Examples of polymeric fine particles include polymer particles made of polystyrene, methacrylate ester or acrylate ester copolymers obtained by soap-free emulsion polymerization, suspension polymerization, or dispersion polymerization, or polycondensation systems such as silicone, benzoguanamine, or nylon, or polymer particles made of thermosetting resins.

[0083] Such fluidizing agents can be surface-treated to increase their hydrophobicity and prevent deterioration of flow properties and charging properties even under high humidity. Examples of preferred surface treatment agents include silane coupling agents, silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oils, and modified silicone oils.

[0084] Examples of cleaning improvers for removing the developer remaining on the photosensitive member or primary transfer medium after transfer include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, and polymer fine particles produced by soap-free emulsion polymerization of, for example, polymethyl methacrylate fine particles, polystyrene fine particles, etc. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 μm to 1 μm.

[0085] The resin particles according to one embodiment have the above-described properties, and therefore can be effectively used as a material for image formation, such as a toner, a developer, a toner set, a toner storage unit, and an image forming apparatus.

[0086] <Toner> The toner according to an embodiment includes the resin particles according to an embodiment, and may be made of the resin particles according to an embodiment. By using the resin particles according to one embodiment in a toner, the environmental impact can be reduced, and even if a plant-derived resin is used, it is possible to provide an image having excellent low-temperature fixability and chargeability, and excellent image quality.

[0087] <Developer> The developer according to an embodiment includes the toner according to an embodiment, and may optionally include other appropriately selected components such as a carrier, etc. This allows for excellent transferability, chargeability, etc., and enables stable formation of high-quality images. The developer may be a one-component developer or a two-component developer, but when used in high-speed printers that correspond to the recent improvements in information processing speed, a two-component developer is preferable in terms of extending the developer life. When the toner according to one embodiment is used in a one-component developer, even if the toner is balanced, there is little variation in the particle size of the toner, and toner filming on the developing roller and toner fusion to components such as blades that thin the toner layer are minimized, resulting in high-quality images being obtained in the developing device.

[0088] When the developer according to an embodiment is used as a two-component developer, it can be mixed with a carrier and used as a developer. When the toner according to an embodiment is used as a two-component developer, the particle size of the toner changes little even when the toner is balanced over a long period of time, and good and stable developability and images can be obtained even when the toner is stirred for a long period of time in a developing device. The content of the carrier in the two-component developer can be appropriately selected depending on the purpose, but is preferably 90 to 98 parts by mass, and more preferably 93 to 97 parts by mass, relative to 100 parts by mass of the two-component developer. The developer according to one embodiment can be suitably used for image formation by various known electrophotographic methods such as a magnetic one-component development method, a non-magnetic one-component development method, and a two-component development method.

[0089] [Career] The carrier is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable that the carrier has a core material and a resin layer (coating layer) that coats the core material.

[0090] (Core material) The core material is not particularly limited and can be selected appropriately depending on the purpose. Examples include manganese-strontium-based materials with a density of 50 emu / g to 90 emu / g and manganese-magnesium-based materials with a density of 50 emu / g to 90 emu / g. To ensure image density, it is preferable to use high-magnetization materials such as iron powder with a density of 100 emu / g or more, or magnetite with a density of 75 emu / g to 120 emu / g. It is also preferable to use low-magnetization materials such as copper-zinc-based materials with a density of 30 emu / g to 80 emu / g, as this can reduce the impact of the developer in a standing state on the photoreceptor and is advantageous for achieving high image quality. These materials may be used alone or in combination of two or more. The volume average particle diameter of the core material is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 10 μm to 150 μm, and more preferably 40 μm to 100 μm. If the volume average particle diameter is 10 μm or more, the amount of fine powder in the carrier increases, which effectively prevents the problem of reduced magnetization per particle and carrier scattering. On the other hand, if the volume average particle diameter is 150 μm or less, the specific surface area decreases, which can cause toner scattering, effectively preventing the problem of poor reproduction of solid areas, especially in full-color printers with many solid areas.

[0091] (resin layer) The resin layer can contain a resin and, if necessary, other components. The resin used in the resin layer can be a known material that can impart the necessary electrostatic property. Specifically, it is preferable to use a silicone resin, an acrylic resin, or a combination of these. Furthermore, it is preferable that the composition for forming the resin layer contains a silane coupling agent. The average thickness of the resin layer is preferably 0.05 μm to 0.50 μm.

[0092] (Measurement method) <Volume average particle size of resin particles> The volume average particle size (Dv) of the resin particles was measured using a Coulter Multisizer III (aperture diameter 100 μm, manufactured by Beckman Coulter) and analysis software Beckman Coulter Multisizer 3 (version 3.51, manufactured by Beckman Coulter). 10 mg of the measurement sample was added to 5 mL of 10 mass % surfactant (alkylbenzene sulfonate, Neogen SC-A, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the mixture was dispersed for 1 minute using an ultrasonic disperser. After that, an arbitrary amount of 25 mL of an electrolyte, Isoton III (manufactured by Beckman Coulter), was added, and the mixture was dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion. Next, 100 mL of the electrolyte and an appropriate amount of the sample dispersion were added to a beaker, and 30,000 particles were measured at a concentration that allowed the particle size of 30,000 particles to be measured in 20 seconds, and the volume average particle size (Dv) was calculated from the particle size distribution.

[0093] <Average circularity of resin particles> The average circularity of the resin particles was measured using a flow particle image analyzer, FPIA-3000 (manufactured by SYSMEX Co., Ltd.). A 1% aqueous solution of NaCl was prepared using grade 1 sodium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and then 50 to 100 ml of the solution was passed through a 0.45 μm filter. 0.1 to 5 mL of alkylbenzene sulfonate (Neogen, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added as a dispersant, and 1 to 10 mg of the sample was added. This was subjected to dispersion treatment for 1 minute using an ultrasonic disperser, and measurements were carried out using a dispersion liquid in which the particle concentration was adjusted to 5000 particles / μl to 15000 particles / μl.

[0094] <Loose apparent density of resin particles> The loose apparent density of resin particles is 10 g of toner in 50 cm 3 The solution was placed in a stoppered measuring cylinder, vigorously shaken up and down 10 times, left for 10 minutes, and then the scale was read and calculated using the following formula.

number

[0095] <Adhesion of resin particles> The adhesive force of the resin particles was measured using an Agrobot manufactured by Hosokawa Micron Corporation. The measurement procedure is as follows. After storing the toner for 24 hours in an environment of 32°C / 54% (with the lid open), 5 g of the toner was filled into a 25 mm diameter, two-partable cell for the agrobot, and after compression, the tensile breaking stress Ft [gf] was measured, which was taken as the adhesive force [gf] of the resin particles. The measurement conditions are as follows: Compression conditions: 0.1 mm / sec, maximum compression force 32 kgf, holding time after compression 60 seconds Tensile conditions: spring linearity 1 mm, tension speed 0.6 mm / sec, tension data sampling start time 0 sec, tension data sampling time 20 s Additional conditions: cell temperature 32℃

[0096] <Specific surface area BET> The specific surface area of ​​the resin particles was calculated by the BET method, which calculates from the amount of nitrogen adsorption. In the present invention, the measurement was performed using a Macsorb HM model-1208 (Mountec Co., Ltd.).

[0097] <Glass transition temperature (Tg)> The glass transition temperature (Tg) of the binder resin can be measured using, for example, a DSC system (differential scanning calorimeter) ("Q-200" manufactured by TA Instruments). Specifically, the glass transition temperature of the target sample can be measured by the following procedure. First, approximately 5.0 mg of the target sample is placed in an aluminum sample container, which is then placed on a holder unit and set in an electric furnace. Next, in a nitrogen atmosphere, the sample is heated from -80°C to 150°C at a heating rate of 10°C / min (first heating). Thereafter, the sample is cooled from 150°C to -80°C at a heating rate of 10°C / min, and further heated to 150°C at a heating rate of 10°C / min (second heating). During each of the first and second heatings, a DSC curve is measured using a differential scanning calorimeter ("Q-200" manufactured by TA Instruments). From the obtained DSC curves, the DSC curve at the first temperature rise can be selected using the analysis program in the Q-200 system, and the glass transition temperature (Tg) of the target sample at the first temperature rise can be determined. Similarly, the DSC curve at the second temperature rise can be selected, and the glass transition temperature (Tg) of the target sample at the second temperature rise can be determined. Unless otherwise specified, the glass transition temperature (Tg) of the binder resin is the glass transition temperature (Tg) at the time of the second temperature rise.

[0098] [Molecular weight measurement] The molecular weight of each component of the binder resin can be measured, for example, by the following method. Gel permeation chromatography (GPC) measurement device: GPC-8220GPC (Manufactured by Tosoh Corporation) Column: TSKgel SuperHZM-H 15cm triple column (Tosoh Corporation) ·Temperature: 40℃ Solvent: THF ·Flow rate: 0.35mL / min Sample: 100 μL of 0.15% by mass sample injected Sample pretreatment: Resin particles are dissolved in tetrahydrofuran (THF) (containing stabilizers, manufactured by Wako Pure Chemical Industries, Ltd.) at 0.15% by mass, then filtered through a 0.2 μm filter. The filtrate is used as the sample. 100 μL of the THF sample solution is injected and measured.

[0099] When measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithm of the calibration curve prepared using several monodisperse polystyrene standard samples and the count number. The standard polystyrene samples used to prepare the calibration curve are Showdex STANDARD (Showa Denko K.K.), Std. Nos. S-7300, S-210, S-390, S-875, S-1980, S-10.9, S-629, S-3.0, and S-0.580. An RI (refractive index) detector is used.

[0100] (Image forming device) Next, regarding one embodiment of the method for forming an image using the image forming apparatus of the present invention, The description will be made with reference to Figure 1. Although a printer is shown as an example of the image forming apparatus of this embodiment, the image forming apparatus is not particularly limited as long as it is capable of forming an image using toner, such as a copier, facsimile, or multifunction machine.

[0101] The image forming apparatus includes a paper feed unit 210 , a conveying unit 220 , an image forming unit 230 , a transfer unit 240 , and a fixing unit 250 . The paper feed section 210 includes a paper feed cassette 211 in which paper sheets P to be fed are stacked, and a paper feed roller 212 that feeds the paper sheets P stacked in the paper feed cassette 211 one by one. The conveying section 220 includes a roller 221 that conveys the paper P fed by the paper feed roller 212 toward the transfer section 240, a pair of timing rollers 222 that hold the leading end of the paper P conveyed by the roller 221 and wait, sending the paper to the transfer section 240 at a predetermined timing, and a paper discharge roller 223 that discharges the paper P with the fixed color toner image onto a paper discharge tray 224.

[0102] The image forming section 230 includes, at predetermined intervals from left to right in the figure, an image forming unit Y that forms an image using a developer containing yellow toner, an image forming unit C that uses a developer containing cyan toner, an image forming unit M that uses a developer containing magenta toner, an image forming unit K that uses a developer containing black toner, and an exposure device 233.

[0103] Image forming unit Image forming unit 180 (180Y, 180C, 180M, 180K) is arranged to be rotatable clockwise in the figure, and includes photosensitive drum 231 (231Y, 231C, 231M, 231K) on which an electrostatic latent image and a toner image are formed, chargers 232 (232Y, 232C, 232M, 232K) that uniformly charge the surface of photosensitive drum 231 (231Y, 231C, 231M, 231K), and cleaners 236 (236Y, 236C, 236M, 236K) that remove toner remaining on the surface of photosensitive drum 231 (231Y, 231C, 231M, 231K).

[0104] Here, the photoreceptor drum is not particularly limited in terms of structure, size, etc., and can be appropriately selected from known photoreceptors. The material of the photoreceptor drum is also not particularly limited and can be appropriately selected depending on the purpose, and examples include inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors (OPCs) such as polysilane and phthalopolymethine. Examples of the organic photoreceptor include a laminated photoreceptor having a laminated structure in which a layer (charge generation layer) in which a charge generation material such as metal-free phthalocyanine or titanyl phthalocyanine is dispersed in a binder resin and a layer (charge transport layer) in which a charge transport material is dispersed in a binder resin are stacked on a support such as an aluminum drum, and a single-layer photoreceptor having a single-layer photosensitive layer on a support in which both a charge generation material and a charge transport material are dispersed in a binder resin. In the single-layer type photoreceptor, a hole transport material and an electron transport material can be added to the photosensitive layer as charge transport materials. An undercoat layer may be provided between the support and the multilayer charge generating layer or the single-layer photosensitive layer.

[0105] Furthermore, the image forming units 180 (180Y, 180C, 180M, 180K) are equipped with toner bottles 234 (234Y, 234C, 234M, 234K) that contain toner of each color, and sub-hoppers 160 (160Y, 160C, 160M, 160K) that replenish the toner supplied from the toner bottles 234 (234Y, 234C, 234M, 234K). Note that when referring to any of the image forming units 180 (180Y, 180C, 180M, 180K), the term "image forming unit" is used.

[0106] The exposure device 233 irradiates the photosensitive drum 231 with laser light L emitted from a light source 233a based on image information, by reflecting the light on a polygon mirror 233b (233bY, 233bC, 233bM, 233bK) that is driven to rotate by a motor.

[0107] The developer contains toner and carrier. The four image forming units 180 (180Y, 180C, 180M, and 180K) have substantially the same mechanical configuration, except for the developer used therein.

[0108] The transfer unit 240 includes a drive roller 241 and a driven roller 242, an intermediate transfer belt 243 that can rotate counterclockwise in the figure as the drive roller 241 is driven, primary transfer rollers (244Y, 244C, 244M, 244K) that are arranged opposite the photosensitive drum 231 across the intermediate transfer belt 243, and secondary opposing rollers 245 and 246 that are arranged opposite each other across the intermediate transfer belt 243 at the position where the toner image is transferred to the paper. In this embodiment, an elastic intermediate transfer belt can also be used as the intermediate transfer belt 243. As the elastic intermediate transfer belt, for example, one in which a flexible elastic layer is laminated on a rigid base layer that can provide relatively flexibility can be used. In order to prevent the intermediate transfer belt 243 from meandering, a guide member for preventing the intermediate transfer belt 243 from shifting may be provided on the inner peripheral surface of the intermediate transfer belt 243 .

[0109] The fixing unit 250 has a heater installed inside and is equipped with a fixing belt 251 that heats the paper P, and a pressure roller 252 that forms a nip by rotatably applying pressure to the fixing belt 251. This applies heat and pressure to the color toner image on the paper P, fixing the color toner image. The paper P with the fixed color toner image is discharged to a paper discharge tray 224 by a paper discharge roller 223, completing the series of image formation processes. [Example]

[0110] The present invention will be specifically explained below with reference to Production Examples, Synthesis Examples, Preparation Examples, Examples, and Comparative Examples, but the present invention is not limited to these Production Examples, Synthesis Examples, Preparation Examples, and Examples. In the Production Examples, Synthesis Examples, Preparation Examples, Examples, and Comparative Examples, unless otherwise specified, "%" indicates "% by mass" and "parts" indicates "parts by mass." Furthermore, the blending amounts in the Examples and Comparative Examples indicate the blending amounts of solids in each raw material.

[0111] <Preparation of amorphous polyester resins A-1 to A-4 for core> The raw materials shown in Table 1 were added to a reactor equipped with a condenser, a stirrer, and a nitrogen inlet tube so that the hydroxyl group to carboxylic acid molar ratio (OH / COOH) was 1.2. Tetrabutoxy titanate (1,000 ppm relative to the total monomer amount) was also added as a condensation catalyst. The mixture was heated to 200°C over 2 hours under a nitrogen stream, then further heated to 230°C over 3 hours, and reacted for 5 hours while distilling off the resulting water. The mixture was then reacted for 3 hours under a reduced pressure of 5 to 15 mmHg. After cooling to 200°C, trimellitic anhydride (as shown in Table 1) was added and reacted for 1 hour at 200°C under normal pressure. The mixture was then further reacted under a reduced pressure of 5 to 20 mmHg until the desired molecular weight was reached, yielding [Core Amorphous Polyester Resins A-1] to [Core Amorphous Polyester Resins A-4].

[0112] <Preparation of amorphous polyester resins B-1 to B-4 for shell> The raw materials shown in Table 1 were added to a reactor equipped with a condenser, a stirrer, and a nitrogen inlet tube so that the molar ratio of hydroxyl groups to carboxylic acid (OH / COOH) was 1.2. Tetrabutoxy titanate (1,000 ppm relative to the total monomer amount) was also added as a condensation catalyst. The mixture was heated to 200°C over 2 hours under a nitrogen stream, then further heated to 230°C over 3 hours, and reacted for 5 hours while distilling off the resulting water. The mixture was then reacted for 3 hours under a reduced pressure of 5 to 15 mmHg. After cooling to 200°C, trimellitic anhydride (as shown in Table 1) was added and reacted for 1 hour at 200°C under normal pressure. The mixture was then further reacted under a reduced pressure of 5 to 20 mmHg until the desired molecular weight was reached, yielding [Shell Amorphous Polyester Resins B-1] to [Shell Amorphous Polyester Resins B-4].

[0113] <Preparation of amorphous polyester resin solutions B-1 to B-4 for shell> 200 parts of [shell amorphous polyester resin B-1] and 200 parts of methyl ethyl ketone were placed in a container and mixed for 60 minutes at 5,000 rpm using a TK Homomixer (manufactured by Primix Corporation) to obtain [shell amorphous polyester resin solution B-1]. [Shell amorphous polyester resin B-2] to [Shell amorphous polyester resin B-4] were also obtained in the same manner as [Shell amorphous polyester resin solution B-1].

[0114] <Preparation of shell aqueous phase 1> 468 parts of water and 132 parts of methyl ethyl ketone were mixed and stirred to obtain a white transparent liquid, which was designated as [shell aqueous phase 1].

[0115] <Preparation of Amorphous Polyester Resin Dispersions B-1 to B-4 for Shell> 400 parts of the [Shell Amorphous Polyester Resin Solution B-1] solution were stirred at 8,000 rpm using a TK Homomixer (manufactured by Primix Corporation). 28% ammonia water was added at a neutralization rate of 100% equivalent to the acid value of [Shell Amorphous Polyester Resin Solution B-1]. After mixing for 10 minutes, 600 parts of [Shell Aqueous Phase 1] were gradually added dropwise to emulsify the [Shell Amorphous Polyester Resin Solution B-1]. The emulsion was then desolvated using an evaporator to obtain [Shell Polyester Resin Dispersion B-1]. The solids content of [Shell Amorphous Polyester Resin Dispersion B-1] was adjusted to 25%.

[0116] [Shell amorphous polyester resin solution B-2] to [Shell amorphous polyester resin solution B-4] were also subjected to the same treatment as that performed on [Shell amorphous polyester resin solution B-1] to obtain [Shell amorphous polyester resin dispersion B-2] to [Shell amorphous polyester resin dispersion B-4]. The solids content of [Shell amorphous polyester resin dispersion B-2] to [Shell amorphous polyester resin dispersion B-4] was adjusted to 25%.

[0117] <Synthesis of crystalline polyester resin C-1> In a reaction vessel equipped with a condenser, a stirrer, a dehydration tube, a thermocouple, and a nitrogen inlet tube, 1,12-dodecanedioic acid and 1,6-hexanediol were charged so that the molar ratio of hydroxyl groups to carboxyl groups (OH / COOH) was 1.2, and trimellitic anhydride was added at a molar ratio of 0.047. Together with titanium tetraisopropoxide (500 ppm relative to the resin components), the mixture was reacted at 180°C for 10 hours, then heated to 200°C and reacted for 3 hours, and then further reacted at a pressure of 8.3 kPa for 2 hours to obtain [Crystalline Polyester Resin C-1].

[0118] <Preparation of Crystalline Polyester Resin Dispersion C-1> A vessel equipped with a stirrer and thermometer was charged with 45 parts of [Crystalline Polyester Resin C-1] and 450 parts of ethyl acetate. The mixture was heated to 80°C under stirring, maintained at 80°C for 5 hours, then cooled to 30°C over 1 hour. The mixture was dispersed in a bead mill (Ultraviscomill, manufactured by Imex Co., Ltd.) at a feed rate of 1 kg / h, a disk peripheral speed of 6 m / s, 80% volumetric loading of 0.5 mm diameter zirconia beads, and 3 passes to obtain a [Crystalline Polyester Resin Dispersion C-1] with a median diameter of 550 nm. The solids concentration of the resulting crystalline polyester resin dispersion was adjusted to 20%.

[0119] <Preparation of Wax Dispersion W-1> A vessel equipped with a stirrer and thermometer was charged with 300 parts of ester wax (WE-11, NOF Corporation, synthetic wax made from plant-derived monomers, melting point 67°C) and 1200 parts of ethyl acetate. The mixture was heated to 80°C with stirring, held at 80°C for 5 hours, then cooled to 30°C. The mixture was then dispersed in a bead mill (Ultraviscomill, Aimex) at a feed rate of 1 kg / hr, a disk peripheral speed of 6 m / s, and 80% volumetric loading of 0.5 mm diameter zirconia beads. Wax dispersion W-1 with a median diameter of 500 nm was obtained. The solids concentration of the resulting wax dispersion was adjusted to 20%.

[0120] <<Measurement of the median diameter of crystalline polyester resin dispersions and wax dispersions>> The median diameters of [Crystalline Polyester Resin Dispersion C-1] and [Wax Dispersion W-1] were measured under the following measurement conditions by adding [Crystalline Polyester Resin Dispersion C-1] or [Wax Dispersion W-1] in the form of a dispersion to a laser diffraction / scattering particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.). [Measurement conditions] Solvent: Ethyl acetate Measurement cell: 10mL batch cell Circulation: Ultrasonic probe 30W, 22.5kHz Measurement sample volume: Transmittance 75% to 90% Measurement time: 20 seconds

[0121] <Preparation of Masterbatch MB-1> 1,200 parts of water, 500 parts of carbon black (Printex 35, manufactured by Dexa) [DBP oil absorption = 42 mL / 100 mg, pH = 9.5], and 500 parts of [amorphous polyester resin A-2] were added and mixed in a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd.). The mixture was kneaded using two rolls at 150°C for 30 minutes, then rolled and cooled, and pulverized in a pulverizer to obtain [masterbatch MB-1].

[0122] Example 1 <Preparation of oil phase> 570 parts of [Amorphous polyester resin for core A-1], 200 parts of [Masterbatch MB-1], 50 parts of [Crystalline polyester resin C-1], and 80 parts of [WAX dispersion W-1] were placed in a container, and the solid content was adjusted to 50% with ethyl acetate. The mixture was mixed at 5,000 rpm for 60 minutes using a TK Homomixer (manufactured by Primix Corporation) to obtain [Oil phase 1]. The above blending amounts indicate the blending amounts of solid content in each raw material.

[0123] <Preparation of aqueous phase> 990 parts of water, 20 parts of sodium dodecyl sulfate, and 90 parts of ethyl acetate were mixed and stirred to obtain a milky white liquid, which was designated as [aqueous phase 1].

[0124] <Emulsification> 900 parts of [Oil Phase 1] were stirred in a TK Homomixer at a rotation speed of 8,000 rpm, and 20 parts of 28% aqueous ammonia were added. After mixing for 10 minutes, 1,200 parts of [Aqueous Phase 1] were gradually added dropwise, and phase inversion emulsification was carried out to obtain [Emulsified Slurry 1].

[0125] <Solvent removal> [Emulsified slurry 1] was placed in a container equipped with a stirrer and a thermometer, and the solvent was removed at 30°C for 180 minutes to obtain [Desolvated slurry 1]. The solid content was adjusted to 25% with ion-exchanged water.

[0126] <Agglutination> 100 parts of [Desolvated Slurry 1] and ion-exchanged water were placed in a container and mixed, and 6 parts of a 20% aqueous magnesium sulfate solution was added dropwise and stirred for another 5 minutes. The mixture was then heated to 55°C and aggregated until the volume average particle size reached approximately 5.0 μm.

[0127] <Shelling process> When the particle size of the cores reached 5.0 μm in the aggregation process, 9.3 parts of [shell amorphous polyester resin dispersion B-1] was added, and 10 parts of a 20% aqueous magnesium sulfate solution was added dropwise and stirred for another 10 minutes, after which the temperature was raised to 65°C and stirring was continued for 30 minutes.

[0128] <Fusing and stopping process> 25 parts of sodium sulfate was added, and the [Agglomerated Slurry 1] was heated to 68°C while stirring, and cooled when the desired average circularity was achieved, to obtain [Dispersed Slurry 1].

[0129] <Annealing process, washing process, and drying process> [Dispersion Slurry 1] was stored at 45°C for 10 hours, filtered under reduced pressure, and washed and dried as follows. (1) 100 parts of ion-exchanged water was added to the filter cake, and the mixture was mixed with a TK homomixer (at 12,000 rpm for 10 minutes) and then filtered. (2): 100 parts of a 10% aqueous sodium hydroxide solution was added to the filter cake of (1), and the mixture was mixed in a TK homomixer (at 12,000 rpm for 30 minutes), followed by filtration under reduced pressure. (3): 100 parts of 10% hydrochloric acid was added to the filter cake of (2), and the mixture was mixed in a TK homomixer (at 12,000 rpm for 10 minutes) and then filtered. (4): 300 parts of ion-exchanged water is added to the filter cake of (3), mixed with a TK homomixer (at 12,000 rpm for 10 minutes), and then filtered. The above steps (1) to (4) were repeated twice to obtain [filter cake 1]. The filtered cake 1 was dried in a circulating air dryer at 45° C. for 48 hours and sieved through a mesh with 75 μm openings to obtain a resin particle matrix 1.

[0130] <External additive processing process> 100 parts of [Resin particle base 1] was mixed with 2.0 parts of hydrophobic silica (HDK-2000, manufactured by Clariant Co., Ltd.) as an external additive in a Henschel mixer, and the mixture was passed through a 500 mesh sieve to obtain [Resin particle 1].

[0131] (Examples 2 to 5, 8 to 14, Comparative Examples 1, 2, and 6) [Resin particles 2] to [Resin particles 5], [Resin particles 8] to [Resin particles 14] of the examples and [Resin particles 15], [Resin particles 16], and [Resin particles 20] of the comparative examples were obtained in the same manner as in Example 1, except that the [Amorphous polyester resin for core] and [Amorphous polyester resin for shell] were changed to those shown in Table 2.

[0132] Example 6 [Resin particles 6] were obtained in the same manner as in Example 1, except that the [amorphous polyester resin for core] was changed to that shown in Table 2 and the amount of 20% magnesium sulfate aqueous solution added in the aggregation step was changed to 5 parts.

[0133] Example 7 [Resin particles 7] were obtained in the same manner as in Example 1, except that the [amorphous polyester resin for core] was changed to that shown in Table 2 and the amount of 20% magnesium sulfate aqueous solution added in the aggregation step was changed to 7 parts.

[0134] (Comparative Example 3) Resin particles 17 were obtained in the same manner as in Example 1, except that the temperature in the fusion step was changed to 70°C.

[0135] Comparative Example 4 [Resin particles 18] were obtained in the same manner as in Example 1, except that in Example 1, the [amorphous polyester resin for core] was changed to that shown in Table 2, the amount of 20% magnesium sulfate aqueous solution added in the aggregation process was changed to 5 parts, and the temperature in the fusion process was changed to 70°C.

[0136] (Comparative Example 5) [Resin particles 19] were obtained in the same manner as in Example 1, except that the acid monomers and alcohol monomers in Example 1 were changed to those shown in Tables 1 and 2, the [amorphous polyester resin for core] and [amorphous polyester resin for shell] in the aggregation step were changed to those shown in Table 2, the amount of 20% magnesium sulfate aqueous solution added in the aggregation step was changed to 7 parts, and the temperature in the fusion step was changed to 70°C.

[0137] (Comparative Examples 7 and 8) [Resin particles 21] and [Resin particles 22] were obtained in the same manner as in Example 1, except that the [Amorphous polyester resin for core] and [Amorphous polyester resin for shell] were those shown in Table 2 and the amount of [Amorphous polyester resin dispersion for shell] in the shell formation step was changed to 4.6 parts.

[0138] (Comparative Examples 9 and 10) [Resin particles 23] and [Resin particles 24] were obtained in the same manner as in Example 1, except that the amorphous polyester resin for core was as shown in Table 2 and the target particle sizes in the aggregation process and shell formation process were 4.4 μm and 6.2 μm, respectively.

[0139] The physical properties of the [Resin Particles 1] to [Resin Particles 24] obtained above are shown in Table 3, and the results of the image evaluation and cleaning property evaluation are shown in Table 4.

[0140] [Table 1]

[0141] [Table 2]

[0142] [Table 3]

[0143] [Table 4]

[0144] (Evaluation method) A carrier used in imagio MP C5503 (manufactured by Ricoh Co., Ltd.) and the resin particles obtained above were mixed so that the concentration of the resin particles was 7% by mass, to obtain a developer.

[0145] <Image fine line reproducibility> [Image fine line reproducibility] The developer was placed in an imagio MP C5503 (manufactured by Ricoh Co., Ltd.), and a printing test of 6-point and 10-point characters was carried out in an environment with a temperature of 30° C. and a relative humidity of 80%. The reproducibility of the printed characters was evaluated on a three-point scale based on the following evaluation criteria. (Evaluation criteria) 〇: 6-point characters are clear △: Some of the 6-point characters are crushed ×: 10-point characters are partially crushed

[0146] <Image blurred> The developer was placed in an imagio MP C5503 (manufactured by Ricoh Co., Ltd.), and 250 A4 size documents with a 25% image area ratio were printed in a single color continuously, and the uniformity of the halftone portion was evaluated. <Evaluation Rank> ◎: No problems at all ○: No problem △: Some problems but acceptable level ×: Problems

[0147] <Cleaning ability> The developer was placed in an imagio MP C5503 (manufactured by Ricoh Co., Ltd.), and a vertical band pattern (relative to the paper running direction) of 43 mm wide and three charts were printed on 20 sheets of A4 size landscape paper. The resulting images were visually observed, and the cleaning performance was evaluated based on the presence or absence of image abnormalities due to poor cleaning. [Evaluation criteria] ⊚: Toner that has slipped through due to poor cleaning cannot be visually confirmed on the printed paper or on the photosensitive member, and no streaks of toner can be confirmed even when observing the photosensitive member longitudinally with a microscope. ◯: Toner that has slipped through due to poor cleaning cannot be visually confirmed on the printed paper or on the photosensitive member. △: Toner that has slipped through due to poor cleaning cannot be visually confirmed on the printed paper, but can be slightly confirmed on the photosensitive drum. ×: Toner that has slipped through due to poor cleaning can be visually confirmed on the printed paper and on the photosensitive member.

[0148] The aspects of the present invention are as follows, for example. (1) Resin particles containing at least a polyester resin as a binder resin, The resin particles have a volume average particle size of 4.5 μm or more and 6.0 μm or less, The loose apparent density of the resin particles is defined as Y (g / cm 3 ) and the circularity is X, the X and the Y satisfy the following relational expressions (1) to (3), The resin particles have an adhesive strength of 150 gf or less. 0.930≦X≦0.980 (1) Y<0.5 (2) Y≧1.5X-1.04 (3) (2) Resin particles according to (1) above, wherein the loose apparent density Y of the resin particles satisfies the following relational expression (4): 0.40≦Y≦0.48 (4) (3) Resin particles according to (1) above, wherein the loose apparent density Y of the resin particles satisfies the following relational expression (5): 0.42≦Y≦0.45 (5) (4) Resin particles according to any one of (1) to (3) above, wherein the polyester resin contains repeating units derived from polyethylene terephthalate (PET), which is a condensate of terephthalic acid and ethylene glycol. (5) The resin particles according to any one of (1) to (4) above, wherein the polyester resin contains a sulfonate group. (6) The resin particles according to any one of (1) to (5) above, wherein the resin particles are granulated in an aqueous medium. (7) A toner comprising the resin particles according to any one of (1) to (5) above. (8) A toner characterized by containing the resin particles described in (6) above. (9) an electrostatic latent image carrier; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier; a developing unit provided with a toner for developing the electrostatic latent image formed on the electrostatic latent image carrier to form a toner image, An image forming apparatus, wherein the toner is the toner described in (7) or (8) above. (10) an electrostatic latent image carrier; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier; a developing unit having a toner for developing the electrostatic latent image formed on the electrostatic latent image carrier to form a toner image; a transfer means for transferring the toner image onto a recording medium; a fixing means for fixing the transferred image on the recording medium, An image forming apparatus, wherein the toner is the toner described in (7) or (8) above. [Explanation of symbols]

[0149] 160Y Sub Hopper (Yellow) 160C Sub Hopper (Cyan) 160M Sub Hopper (Magenta) 160K Sub Hopper (Black) 180Y Image Forming Unit (Yellow) 180C Image Forming Unit (Cyan) 180M Image Forming Unit (Magenta) 180K Image Forming Unit (Black) 210 Paper feed section 211 Paper cassette 212 Paper feed roller 220 Conveyor 221 Laura 222 Timing roller 223 Paper ejection roller 224 Paper output tray 230 Image creation section 231Y Photoconductor drum (yellow) 231C Photoconductor drum (cyan) 231M Photoconductor Drum (Magenta) 231K Photoconductor Drum (Black) 232Y Charger (Yellow) 232C Charger (cyan) 232M Charger (Magenta) 232K Charger (Black) 233 Exposure device 233a light source 233bY Polygon Mirror (Yellow) 233bC Polygon Mirror (Cyan) 233bM Polygon Mirror (Magenta) 233bK Polygon Mirror (Black) 234Y Toner Bottle (Yellow) 234C Toner Bottle (Cyan) 234M Toner Bottle (Magenta) 234K Toner Bottle (Black) 236Y Cleaning Device (Yellow) 236C Cleaner (cyan) 236M Cleaner (Magenta) 236K Cleaning Tool (Black) 240 Transcription Unit 241 Drive roller 242 driven roller 243 Intermediate transfer belt 244 Primary transfer roller 244Y Primary Transfer Roller (Yellow) 244C Primary transfer roller (cyan) 244M Primary Transfer Roller (Magenta) 244K Primary Transfer Roller (Black) 245 Secondary opposing roller 246 Secondary transfer roller 250 Fixing unit 251 Fixing belt 252 pressure roller L Laser P paper [Prior art documents] [Patent documents]

[0150] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-268479

Claims

1. Resin particles containing at least a polyester resin as a binder resin, The resin particles have a volume average particle size of 4.5 μm or more and 6.0 μm or less, The loose apparent density of the resin particles is defined as Y (g / cm ３ ) and the circularity is X, the X and the Y satisfy the following relational expressions (1) to (3), The resin particles have an adhesive strength of 150 gf or less. 0.930≦X≦0.980 (1) Y<0.5 (2) Y≧1.5X-1.04 (3)

2. The resin particles according to claim 1 , wherein the loose apparent density Y of the resin particles satisfies the following relational expression (4): 0.40≦Y≦0.48 (4)

3. The resin particles according to claim 1 , wherein the loose apparent density Y of the resin particles satisfies the following relational expression (5): 0.42≦Y≦0.45 (5)

4. 2. The resin particles according to claim 1, wherein the polyester resin contains repeating units derived from polyethylene terephthalate (PET), which is a condensation product of terephthalic acid and ethylene glycol.

5. The resin particles according to claim 1 , wherein the polyester resin contains a sulfonate group.

6. The resin particles according to claim 1 , wherein the resin particles are granulated in an aqueous medium.

7. A toner comprising the resin particles according to claim 1.

8. A toner comprising the resin particles according to claim 6.

9. an electrostatic latent image carrier; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier; a developing unit provided with a toner for developing the electrostatic latent image formed on the electrostatic latent image carrier to form a toner image, 9. An image forming apparatus, wherein the toner is the toner according to claim 7.

10. an electrostatic latent image carrier; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier; a developing unit having a toner for developing the electrostatic latent image formed on the electrostatic latent image carrier to form a toner image; a transfer means for transferring the toner image onto a recording medium; a fixing means for fixing the transferred image on the recording medium, 9. An image forming apparatus, wherein the toner is the toner according to claim 7.

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