toner

Abstract

To provide a toner that achieves both high image glossiness and image stacking properties.SOLUTION: A toner has toner particles having a binder resin and an ester compound A. The binder resin contains a styrene-acrylic resin having a unit represented by the following formula (1). The ester compound A is an ester compound represented by the following formula (2) or the following formula (3). The absolute value of the difference between SPb (J / cm3)1 / 2 that is the SP value of the styrene-acrylic resin and SPw1 (J / cm3)1 / 2 that is the SP value of the ester compound A is 1.00 or more and 2.00 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a toner used in a recording method using an electrophotographic method, an electrostatic recording method, and a toner jet recording method.

Background Art

[0002] In recent years, the application area of electrophotographic image formation has been expanding from offices to commercial printing. Although the image quality required for commercial printing applications is diverse, particularly in the field of photo printing, it is required to output high-printing-rate and high-gloss images at high speed. In order to output high-printing-rate and high-gloss images at high speed, excellent melting characteristics that sufficiently reduce the viscosity even with short-time heating are required for the toner. In order to meet such requirements, various studies have been conducted on the binder resin used in the toner. Among them, as a binder resin having excellent melting characteristics, studies on styrene-acrylic resins incorporating long-chain alkyl (meth) acrylates have been conducted.

[0003] Patent Document 1 discloses an electrostatic charge image developing toner containing a styrene-acrylic resin having a structural unit derived from a (meth) acrylic acid alkyl ester monomer having 8 to 22 carbon atoms in the alkyl group and a structural unit derived from a (meth) acrylic acid alkyl ester monomer having 1 to 7 carbon atoms in the alkyl group, and containing a crystalline ester compound. It is also disclosed that pentaerythritol tetrabehenate can be used as the wax. Patent Document 1 controls the affinity between the crystalline ester compound and the binder resin by using a styrene-acrylic resin, and improves the melting characteristics of the toner. However, when high-printing-rate images are continuously output using the toner of Patent Document 1, problems with image stacking, where the images stick together, became apparent. Also, when pentaerythritol tetrabehenate is used as the wax in the toner of Patent Document 1, no improvement in image stacking was observed.

[0004] On the other hand, Patent Document 2 discloses a toner binder resin containing a vinyl copolymer formed by copolymerizing monomer components, which include 10 to 30% by mass of an alkyl (meth)acrylate monomer with 8 or more carbon atoms in the alkyl group and 0.2 to 2% by mass of an alkyldiol diacrylate monomer with 6 or more carbon atoms in the alkylene group, and Fischer-Tropsch wax. The binder resin described in Patent Document 2 has a crosslinked structure formed by the alkyldiol acrylate monomer with 6 or more carbon atoms, which increases the viscosity of the image surface after fixing and suppresses the adhesion of images to each other. However, the method described in Patent Document 2 has the problem that sufficient image gloss cannot be obtained in a high-speed process.

[0005] Thus, toners using styrene-acrylic resins incorporating long-chain alkyl acrylates as the binder resin can achieve high image gloss, but they have issues with image stacking, and there was a need to achieve a high level of both. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2014-035506 [Patent Document 2] Japanese Patent Publication No. 2007-322477 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This invention provides a toner that achieves both high image gloss and image stacking performance. [Means for solving the problem]

[0008] The present invention relates to a toner having toner particles having a binder resin and an ester compound A, The binder resin contains a styrene-acrylic resin having a unit represented by the following formula (1), The ester compound A is an ester compound represented by the following formula (2) or the following formula (3), SPb (J / cm 3 ), which is the SP value of the styrene-acrylic resin 1 / 2 and SPw1 (J / cm 3 ), which is the SP value of the ester compound A 1 / 2 and the absolute value of the difference therebetween is 1.00 or more and 2.00 or less relates to a toner characterized thereby.

Chemical formula

Chemical formula

Chemical formula

Advantages of the Invention

[0009] According to the present invention, a toner capable of achieving both high image gloss and image loadability can be provided.

Embodiments for Carrying Out the Invention

[0010] In the present invention, the description of "〇〇 to ××" representing a numerical range means a numerical range including the lower limit and the upper limit, which are the endpoints, unless otherwise specified.

[0011] The toner of the present invention is a toner having toner particles containing a binder resin and an ester compound A, where the binder resin contains a styrene-acrylic resin having a unit represented by the following formula (1), The ester compound A is an ester compound represented by formula (2) or formula (3), The SP value of the styrene-acrylic resin is SPb (J / cm²). 3 ) 1 / 2 and the SP value of the ester compound A is SPw1 (J / cm²). 3 ) 1 / 2 The absolute value of the difference between the two is characterized by being between 1.00 and 2.00. [ka] In formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 This represents a linear alkyl group having 10 to 14 carbon atoms. [ka] [ka] In equations (2) and (3), R 11 ~R 14 and R 21 ~R 26 Each of these independently represents a linear alkyl group having 15 to 21 carbon atoms.

[0012] Although the exact factors that enabled the toner of this invention to achieve both high image gloss and image stacking performance are unclear, the inventors speculate as follows. The unit represented by equation (1) (hereinafter also referred to as the "long-chain acrylate moiety") has high molecular chain mobility. Therefore, resins containing long-chain acrylate moieties have a high degree of freedom during melting and are easily made low-viscosity. Consequently, when used as a binder resin for toner, the image surface after fixing tends to be smooth, and high image gloss can be obtained. On the other hand, because the long-chain acrylate moieties present on the image surface after fixing have high molecular chain mobility, the parts that come into contact with the next printed paper tend to stick, and this can cause image sticking, especially when printing at high print density and high speed.

[0013] Generally, reducing the mobility of molecular chains is effective in suppressing image adhesion. Specifically, a known method involves crosslinking the main chains of a resin with a crosslinking agent to reduce molecular chain mobility.

[0014] However, resins containing long-chain acrylate moieties have high side-chain mobility, so even if the main chain is crosslinked, the mobility of the side chains may not decrease, and sufficient image loading may not be obtained. Also, when image adhesion is suppressed by crosslinking the main chains of the resin, the mobility of the molecular chains decreases regardless of the temperature range, which tends to hinder the reduction of viscosity during fixing. Therefore, it was found that there is a trade-off relationship between image gloss and image loading. To resolve the trade-off relationship, a configuration in which the molecular chain has a high degree of freedom during fixation and a decrease in the degree of freedom after fixation is considered effective.

[0015] In this invention, the above problem is solved by a toner having a specific styrene-acrylic resin having a long-chain acrylate moiety and a specific ester compound A. The long-chain acrylate moiety is a unit having a linear alkyl group with 10 to 14 carbon atoms, and ester compound A is an ester compound having 4 to 6 linear alkyl groups with 15 to 21 carbon atoms in its molecule. Furthermore, the SP value of the styrene-acrylic resin is SPb (J / cm²). 3 ) 1 / 2 The SP value of ester compound A is SPw1 (J / cm²). 3 ) 1 / 2 The absolute value of the difference between these two values ​​is between 1.00 and 2.00.

[0016] In the above configuration, controlling the SP values ​​of the styrene-acrylic resin and ester compound A increases the affinity between the styrene-acrylic resin and ester compound A. Therefore, the linear alkyl groups of ester compound A can interact with the linear alkyl groups of the long-chain acrylate moiety. Since the linear alkyl groups of the long-chain acrylate moiety and the linear alkyl groups of ester compound A have similar structures, at room temperature they adopt an oriented structure, resulting in low mobility of the linear alkyl groups. Furthermore, because ester compound A has multiple linear alkyl groups, the styrene-acrylic resin forms a pseudo-crosslinked structure via ester compound A, reducing the mobility of the main chain. On the other hand, at temperatures above the melting point of ester compound A, the orientation of the linear alkyl groups is released, resulting in high mobility of the linear alkyl groups. Thus, the configuration of the present invention allows for high mobility of the linear alkyl groups of the long-chain acrylate moiety at high temperatures and low mobility of the linear alkyl groups of the long-chain acrylate moiety at room temperature. In other words, it becomes possible to control the mobility of the linear alkyl group in the long-chain acrylate moiety by controlling the temperature.

[0017] As described above, in this invention, during fixing at high temperatures, the mobility of the linear alkyl groups in the long-chain acrylate moiety is high, resulting in a decrease in the viscosity of the entire resin. Therefore, it is possible to obtain high image gloss. On the other hand, when the temperature is lowered after fixing, the linear alkyl groups in the long-chain acrylate moiety orient with the linear alkyl groups in ester compound A, thereby reducing the mobility of both the linear alkyl groups and the main chain. Therefore, adhesion between images can be suppressed, and image stacking performance is improved.

[0018] Next, the configuration of the present invention will be described in more detail below. <Binding resin> The binder resin contained in the toner particles contains a styrene-acrylic resin having a unit represented by formula (1). [ka]

[0019] The inclusion of a styrene-acrylic resin allows for lower viscosity during fixing, improving image gloss. Furthermore, when combined with ester compound A, described later, image adhesion can be suppressed, improving image loading performance.

[0020] In formula (1), R 1 R is a hydrogen atom or a methyl group. Also, in formula (1), R 2 R is a linear alkyl group having 10 to 14 carbon atoms. 2 Because the linear alkyl group is linear, the viscosity of the resin is reduced, and it becomes possible to orient with the linear alkyl group in ester compound A. Therefore, the effects of improved image gloss and improved image stacking are obtained. Furthermore, if the number of carbon atoms is 10 or more, the effect of reducing the viscosity of the resin is easier to obtain, and the image gloss is improved. If the number of carbon atoms is 14 or less, the orientation of the linear alkyl group in the resin and the linear alkyl group in ester compound A occurs preferentially over the orientation of linear alkyl groups in the resin with each other, thus improving image stacking. 2 The linear alkyl group represented by is more preferably 12 carbon atoms.

[0021] The styrene-acrylic resin is preferably a styrene-acrylic resin having 1% to 15% by mass of the unit represented by formula (1). When the content of the unit represented by formula (1) is 1% to 15% by mass, a sufficient viscosity reduction effect is obtained, improving image gloss. In addition, the orientation of the linear alkyl groups of the long-chain acrylate moieties is suppressed, improving image stacking performance. The styrene-acrylic resin is more preferably a styrene-acrylic resin containing 2% to 10% by mass of the unit represented by formula (1).

[0022] The styrene-acrylic resin contains the unit shown in formula (7) in addition to the unit shown in formula (1). The styrene-acrylic resin preferably contains the unit shown in formula (7) in an amount of 1% by mass or more and 99% by mass or less, and more preferably 50% by mass or more and 90% by mass or less. [ka] In formula (7), R 61 This represents a hydrogen atom or a methyl group.

[0023] SP value of styrene-acrylic resin: SPb (J / cm 3 ) 1 / 2 In this case, an SPb of 19.50 to 20.40 is preferable from the viewpoint of easily increasing affinity with ester compound A, which will be described later. More preferably, it is 19.80 to 20.10. SPb can be controlled by the type and amount of units constituting the styrene-acrylic resin.

[0024] The weight-average molecular weight of the styrene-acrylic resin is preferably between 10,000 and 500,000. The weight-average molecular weight can be controlled by factors such as the reaction temperature and the amount of initiator used during the production of the styrene-acrylic resin.

[0025] The glass transition temperature of styrene-acrylic resins is preferably between 40°C and 60°C. The glass transition temperature can be controlled by the type and amount of units that make up the styrene-acrylic resin.

[0026] The binder resin preferably contains 80% by mass or more of a styrene-acrylic resin. In addition, as the binder resin of the present invention, conventionally known resins can be used simultaneously with the styrene-acrylic resin without any particular limitations as needed. Examples of binder resins that can be used simultaneously with the styrene-acrylic resin include vinyl resins other than styrene-acrylic resins, polyester resins, polyurethane resins, polyamide resins, and the like.

[0027] <polymerizable monomers> Styrene-acrylic resins may also be obtained by polymerization. Examples of polymerizable monomers that form the unit represented by formula (1) of the styrene-acrylic resin include acrylic acid esters and methacrylic acid esters such as decyl acrylate, decyl methacrylate, lauryl acrylate, lauryl methacrylate, myristyl acrylate, and myristyl methacrylate. Among these, the use of lauryl acrylate or lauryl methacrylate is preferred.

[0028] Furthermore, the polymerizable monomers that form the unit represented by formula (7) of the styrene-acrylic resin are styrene and α-methylstyrene. Among these, styrene is preferred.

[0029] In addition to the units represented by formulas (1) and (7), the styrene-acrylic resin may also have units derived from conventionally known polymerizable monomers without any particular limitations. Examples of polymerizable monomers include monofunctional monomers having one polymerizable unsaturated bond in the molecule, such as acrylic acid esters like methyl acrylate and n-butyl acrylate (n-butyl acrylate); methacrylic acid esters like methyl methacrylate, 2-hydroxyethyl methacrylate, t-butyl methacrylate, and 2-ethylhexyl methacrylate; unsaturated carboxylic acids like acrylic acid and methacrylic acid; unsaturated dicarboxylic acids like maleic acid; unsaturated dicarboxylic acid anhydrides like maleic anhydride; nitrile vinyl monomers like acrylonitrile; halogen-containing vinyl monomers like vinyl chloride; and nitro vinyl monomers like nitrostyrene; as well as polyfunctional monomers having multiple polymerizable unsaturated bonds in the molecule, such as divinylbenzene, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, and trimethylolpropane tri(meth)acrylate. Among these, it is preferable to use acrylic acid esters or methacrylic acid esters, and it is even more preferable to use n-butyl acrylate.

[0030] <Ester compound A> The toner particles have an ester compound A represented by formula (2) or formula (3). [ka] [ka] In equations (2) and (3), R 11 ~R 14 and R 21 ~R 26 Each of these independently represents a linear alkyl group having 15 to 21 carbon atoms.

[0031] By combining ester compound A with a styrene-acrylic resin, it is possible to suppress image adhesion and improve image loading performance.

[0032] The SP value of ester compound A is SPw1 (J / cm²). 3 ) 1 / 2 In this case, the SP value of the styrene-acrylic resin is SPb (J / cm²). 3 ) 1 / 2 The SP value of ester compound A is SPw1 (J / cm²). 3 ) 1 / 2 The absolute value of the difference between SPw1 and SPb is 1.00 or more and 2.00 or less. When the absolute value of the difference is 1.00 or more and 2.00 or less, the affinity between ester compound A and styrene-acrylic resin increases, allowing ester compound A to interact with the styrene-acrylic resin, thus improving image loading performance. It is more preferable that the absolute value of the difference between SPw1 and SPb is 1.50 or more and 1.90 or less. On the other hand, if the absolute value of the difference between SPw1 and SPb is less than 1.00, the affinity between ester compound A and styrene-acrylic resin is too high, so ester compound A may not separate during fixing, and the effect of reducing viscosity may be insufficient. Also, if the absolute value of the difference between SPw1 and SPb exceeds 2.00, ester compound A and styrene-acrylic resin do not interact, so the effect of improving image loading performance cannot be obtained. For this reason, it is preferable that SPw1 is 18.00 or more and 18.50 or less. More preferably, SPw1 is 18.10 or more and 18.40 or less. SPw1 can be controlled by the number of carbon atoms in the linear alkyl group and the number of ester bonds in ester compound A.

[0033] When the number of carbon atoms in the linear alkyl group of ester compound A is C1, and the number of carbon atoms in the linear alkyl group of the unit represented by formula (1) is C2, it is preferable that the following formula (a) is satisfied. 4≦C1-C2≦10 Formula (a)

[0034] By satisfying formula (a), even if ester compound A is oriented with the styrene-acrylic resin before fixing, the orientation is easily released during the heating process during fixing, and the effect of lowering viscosity can be fully obtained. Therefore, the effect of improving image gloss is easily obtained. In addition, orientation during cooling is also more likely to occur, so the image stackability is further improved. It is more preferable that C1 and C2 satisfy the following formula (a'). 6≦C1-C2≦10 Formula (a')

[0035] Ester compound A is preferably an ester compound represented by formula (2') or formula (3'). [ka] [ka] In equations (2') and (3'), R 11 ~R 14 and R 21 ~R 26 Each of these independently represents a linear alkyl group having 17 to 21 carbon atoms.

[0036] If ester compound A is the ester compound represented by formula (2') or formula (3'), then during fixing, ester compound A partially separates and functions as a release agent, thereby improving the release properties of the image. Furthermore, it is more preferable that ester compound A is the ester compound represented by formula (2'). Because the ester compound represented by formula (2') has high mobility, the dispersibility of the ester compound in the image from fixing to cooling is improved. Therefore, the styrene-acrylic resin can form a more uniform pseudo-crosslinked structure via the ester compound represented by formula (2'). As a result, the uniformity of the image gloss is improved.

[0037] Examples of ester compound A include pentaerythritol tetrapalmitate, pentaerythritol tetrastearate, pentaerythritol tetraeicosanate, pentaerythritol tetrabehenate, dipentaerythritol hexapalmitate, dipentaerythritol hexastearate, dipentaerythritol hexaeicosanate, and dipentaerythritol hexabehenate.

[0038] The melting point of ester compound A is preferably 70°C or higher and 90°C or lower, more preferably 75°C or higher and 90°C or lower, and even more preferably 75°C or higher and 85°C or lower. The molecular weight of ester compound A is preferably between 1000 and 2200, and more preferably between 1200 and 2200. The content of ester compound A is preferably 1.0 part by mass or more and 20.0 parts by mass or less, more preferably 2.0 parts by mass or more and 15.0 parts by mass or less, and even more preferably 3.0 parts by mass or more and 12.0 parts by mass or less, per 100.0 parts by mass of the binder resin.

[0039] <Ester compound B> Toner particles are represented by the following formulas (4), (5), or (6), and the SPb (J / cm) of the styrene-acrylic resin. 3 ) 1 / 2 The SP value of ester compound B is SPw2 (J / cm²). 3 ) 1 / 2It is preferable to contain ester compound B, the absolute value of the difference between the two compounds is 2.10 or less. [ka] [ka] [ka] In equations (4), (5), and (6), R 31 and R 41 Each independently represents an alkylene group with 2 to 8 carbon atoms, R 32 , R 33 , R 42 , R 43 , R 51 and R 52 Each of these independently represents a linear alkyl group having 14 to 24 carbon atoms.

[0040] Because ester compound B has high compatibility with styrene-acrylic resin, it can achieve a lower viscosity at lower temperatures. Therefore, even when fixed at lower temperatures, a high image gloss can be obtained.

[0041] Compounds represented by formula (4) include ethylene glycol dipalmitate, ethylene glycol distearate, ethylene glycol dieicosanate, ethylene glycol dibehenate, ethylene glycol ditetracosanate, butanediol distearate, butanediol dibehenate, hexanediol distearate, hexanediol dibehenate, octanediolic acid distearate, and octanediolic acid dibehenate. Compounds represented by formula (5) include distearyl succinate, dibehenyl succinate, distearyl adipate, dibehenyl adipate, distearyl suberate, dibehenyl suberate, distearyl sebacate, and dibehenyl sebacate. Compounds represented by formula (6) include palmityl palmitate, stearyl palmitate, behenyl palmitate, palmityl stearate, stearyl stearate, behenyl stearate, palmityl behenate, stearyl behenate, and behenyl behenate.

[0042] Ester compound B is preferably an ester compound represented by formula (4) or formula (5) because it easily enhances compatibility with styrene-acrylic resins having the unit represented by formula (1). Because the ester compound represented by formula (4) or formula (5) has a linear structure, it exhibits sharp melting characteristics, and because it has multiple ester bonds in its molecule, it is easy to control the difference in SP value with styrene-acrylic resins. Therefore, the effect of reducing the viscosity of the toner is further enhanced.

[0043] Ester compound B is more preferably an ester compound represented by formula (4') or formula (5'). [ka] [ka] In equations (4') and (5'), R 31 and R 41 This indicates an ethylene group, R 32 , R 33 , R42 , R 43 Each of these independently represents a linear alkyl group having 16 to 22 carbon atoms.

[0044] SPb (J / cm²) of styrene-acrylic resin 3 ) 1 / 2 The SP value of ester compound B is SPw2 (J / cm²). 3 ) 1 / 2 The absolute value of the difference between SPb and SPw2 is preferably 2.10 or less. When the absolute value of the difference between SPb and SPw2 is 2.10 or less, the ester compound B becomes more compatible with the styrene-acrylic resin, so that high image gloss can be obtained even when fixed at low temperatures. The absolute value of the difference between SPb and SPw2 is more preferably 2.00 or less. An SPw2 of 17.90 to 18.50 is preferable from the viewpoint of easily increasing affinity with styrene-acrylic resins. More preferably, an SPw2 of 18.00 to 18.20 is preferable.

[0045] Furthermore, it is preferable that the SP value of ester compound B, SPw2, is lower than the SP value of ester compound A, SPw1. When SPw2 is lower than SPw1, the linear alkyl group of the long-chain acrylate moiety is oriented preferentially to ester compound A rather than ester compound B during cooling after fixing, making it easier to obtain the effect of improved image stacking. SPw2 can be controlled by the number of carbon atoms in the linear alkyl group of ester compound B and the number of ester bonds.

[0046] The melting point of ester compound B is preferably 65°C to 90°C, and more preferably 70°C to 85°C. Furthermore, it is preferable that the melting point of ester compound B is lower than that of ester compound A. Because the melting point of ester compound B is lower than that of ester compound A, ester compound B melts first during the heating process during fixing, thus enhancing the effect of lowering viscosity, and during the cooling process after fixing, the mobility of ester compound A decreases first, thus enhancing the effect of improving image loading.

[0047] The molecular weight of ester compound B is preferably 500 to 900, and more preferably 550 to 850. For the reasons stated above, it is more preferable to use ethylene glycol distearate as the ester compound B.

[0048] The content of ester compound B is preferably 1.0 part by mass or more and 40.0 parts by mass or less, more preferably 3.0 parts by mass or more and 30.0 parts by mass or less, and even more preferably 5.0 parts by mass or more and 25.0 parts by mass or less, per 100.0 parts by mass of the binder resin.

[0049] Next, we will describe in detail the internal additives other than those mentioned above, which can be used in toner particles. <Release agent> The toner particles may contain known waxes as release agents in addition to the binder resin, ester compound A, and ester compound B. Examples of mold release agents include paraffin wax, microcrystalline wax, petroleum-based waxes such as petrolatum and their derivatives, montan wax and its derivatives, hydrocarbon waxes produced by the Fischer-Tropsch process and their derivatives, polyolefin waxes such as polyethylene and their derivatives, natural waxes such as carnauba wax and candelilla wax and their derivatives. Derivatives also include oxides, block copolymers with vinyl monomers, and graft-modified products. These can be used alone or in combination.

[0050] <Coloring agent> Toner particles may contain colorants. As colorants, conventionally known black, yellow, magenta, and cyan pigments and dyes, magnetic materials, and other colors can be used without particular limitations. Examples of black colorants include black pigments such as carbon black.

[0051] Examples of yellow colorants include yellow pigments and dyes such as monoazo compounds, disazo compounds, condensed azo compounds, isoindolinone compounds, benzimidazolon compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specifically, examples include CI Pigment Yellow 74, 93, 95, 109, 111, 128, 155, 174, 180, 185, and CI Solvent Yellow 162.

[0052] Examples of magenta colorants include magenta pigments and dyes such as monoazo compounds, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolon compounds, thioindigo compounds, and perylene compounds. Specifically, examples include CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221, 238, 254, 269, and CI Pigment Violet 19.

[0053] Examples of cyanide colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and cyanide pigments and dyes such as basic dye lake compounds. Specifically, examples include CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.

[0054] The colorant content is preferably 1.0 part by mass or more and 20.0 parts by mass or less per 100.0 parts by mass of the binder resin or polymerizable monomer.

[0055] Furthermore, toner can also be made into magnetic toner by incorporating magnetic materials. In this case, the magnetic material can also serve as a coloring agent. Examples of magnetic materials include iron oxides such as magnetite, hematite, and ferrite; metals such as iron, cobalt, and nickel; and alloys and mixtures of these metals with metals such as aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium. When a magnetic material is used as a coloring agent, the magnetic material content is preferably 30.0 parts by mass or more and 100.0 parts by mass or less per 100.0 parts by mass of the binder resin.

[0056] <Charge control agent> The toner particles may contain a charge control agent. Any known charge control agent can be used without any particular limitations.

[0057] Examples of negative charge control agents include metal compounds of aromatic carboxylic acids such as salicylic acid, alkyl salicylic acid, dialkyl salicylic acid, naphthoic acid, and dicarboxylic acid, or polymers or copolymers having such metal compounds; polymers or copolymers having sulfonic acid groups, sulfonic acid bases, or sulfonic acid ester groups; metal salts or metal complexes of azo dyes or azo pigments; boron compounds, silicon compounds, calixarenes, and the like.

[0058] On the other hand, examples of positive charge control agents include quaternary ammonium salts, polymeric compounds having quaternary ammonium salts in their side chains, guanidine compounds, nigrosine compounds, and imidazole compounds. As polymers or copolymers having a sulfonic acid base or sulfonic acid ester group, monopolymers of sulfonic acid group-containing vinyl monomers such as styrene sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, vinyl sulfonic acid, and methacrylic sulfonic acid, or copolymers of vinyl monomers and sulfonic acid group-containing vinyl monomers as described in the section on binder resins, can be used. The charge control agent content is preferably 0.01 parts by mass or more and 5.0 parts by mass or less per 100.0 parts by mass of the binder resin.

[0059] <External Additives> The toner of the present invention may contain external additives. There are no particular restrictions on the use of conventionally known external additives. External additives include raw silica nanoparticles such as wet-process silica and dry-process silica, or surface-treated silica nanoparticles obtained by surface-treating these raw silica nanoparticles with treatment agents such as silane coupling agents, titanium coupling agents, and silicone oil; metal oxide nanoparticles such as titanium oxide nanoparticles, aluminum oxide nanoparticles, and zinc oxide nanoparticles, or metal oxide nanoparticles obtained by hydrophobizing metal oxides; fatty acid metal salts such as zinc stearate, calcium stearate, and zinc stearate; metal complexes of aromatic carboxylic acids such as salicylic acid, alkyl salicylic acid, dialkyl salicylic acid, naphthoic acid, and dicarboxylic acid; clay minerals such as hydrotalcite; and fluorine-based resin nanoparticles such as vinylidene fluoride nanoparticles and polytetrafluoroethylene nanoparticles.

[0060] In particular, it is preferable to use clay minerals such as hydrotalcite. Because clay minerals have high water retention, their presence on the image surface after fixing can suppress deterioration due to drying of the image surface, which is especially noticeable in high-print-rate images. This effect is particularly easily obtained when a highly hydrophobic resin, such as the styrene-acrylic resin of the present invention, is used as the binder resin.

[0061] Furthermore, from the viewpoint of fluidity and electrostatic stability, it is preferable to use silica nanoparticles obtained by treating raw silica nanoparticles with silicone oil.

[0062] The content of the external additive in the toner of the present invention is preferably 0.1 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of toner particles.

[0063] <Average circularity of toner> The average circularity of the toner is preferably between 0.940 and 0.995. When the average circularity of the toner is within this range, the image surface after fixing tends to be smoother, and the gloss of the fixed image is further improved. The average circularity of the toner is more preferably between 0.950 and 0.995. The method for measuring the average circularity of the toner will be described later.

[0064] Next, the method for obtaining the toner of the present invention will be described in detail below. <Manufacturing of toner particles> The method for producing toner particles of the present invention can utilize known means, including kneading and grinding methods and wet manufacturing methods. From the viewpoint of uniform particle size and shape control, wet manufacturing methods are preferably used. Furthermore, examples of wet manufacturing methods include suspension polymerization, dissolution and suspension, and emulsification and agglutination methods, and emulsification and agglutination methods are preferably used because they can improve the dispersion state of ester compound A.

[0065] A specific example of producing the toner particles of the present invention by an emulsification agglutination method is a production example having the following steps (1) and (2). (1) A resin fine particle dispersion preparation step, in which a binder resin fine particle for core particles is formed by polymerization of a binder resin in an aqueous medium, and a dispersion is prepared in which the binder resin fine particle is dispersed. (2) A toner particle formation step in which binder resin fine particles are aggregated in an aqueous medium to form toner particles.

[0066] The following describes steps (1) and (2) in detail. (1) Resin particle dispersion preparation process In the resin fine particle dispersion preparation process, binder resin fine particles are formed, which are then used in the toner particle formation process. Specifically, the binder resin microparticles are produced by adding a monomer solution to an aqueous medium containing a surfactant, in which a polymerizable monomer and ester compound A for forming the binder resin, along with optional internal additives such as ester compound B, a mold release agent, and a charge control agent, are dissolved or dispersed. Mechanical energy is then applied to form droplets of the monomer solution, and then a water-soluble radical polymerization initiator is added to allow the polymerization reaction to proceed within the monomer solution droplets. Note that the monomer solution droplets may also contain an oil-soluble polymerization initiator. In this polymerization of the binder resin, a process of forcibly emulsifying by applying mechanical energy may be carried out. Means of applying such mechanical energy include strong stirring such as a homomixer or ultrasound, or means of applying ultrasonic vibration energy. When polyester resin microparticles are used as the binder resin microparticles, it is preferable to synthesize the polyester resin by a normal polycondensation reaction and then microparticleize it. Methods for preparing a dispersion of polyester resin fine particles include pulverizing the polyester resin by mechanical means and dispersing it in an aqueous medium using a surfactant, and a phase inversion emulsification method; either method may be used.

[0067] When obtaining a resin fine particle dispersion by emulsion polymerization, the polymerizable monomers listed in the section on polymerizable monomers above can be used. For the polymerization initiator, known polymerization initiators can be used. Further details will be provided later.

[0068] When a surfactant is used in the resin fine particle dispersion preparation process, any known surfactant can be used. Details will be described later.

[0069] In addition to the binder resin and ester compound A, the toner particles may optionally contain internal additives such as ester compound B, colorants, release agents, and charge control agents. Such internal additives can be introduced into the toner particles, for example, by dissolving or dispersing them in a monomer solution for forming the binder resin beforehand during the lipid microparticle dispersion preparation process.

[0070] Furthermore, such internal additives can also be introduced into toner particles by preparing a dispersion of internal additive microparticles consisting solely of the internal additive, and then agglomerating the internal additive microparticles together with resin microparticles and colorant microparticles during the toner particle formation process. The above materials can be used as internal additives.

[0071] (2) Toner particle formation process In this toner particle formation process, if necessary, fine particles of other toner components such as ester compound B, colorants, release agents, and charge control agents can be aggregated together with the binder resin fine particles and ester compound A fine particles.

[0072] The following method is a specific method for agglomerating and fusing binder resin microparticles, ester compound A microparticles, and other internal additive microparticles. A flocculant is added to an aqueous medium to a concentration above the critical flocculation concentration, and then heated to a temperature above the glass transition temperature of the binder resin microparticles and ester compound A microparticles, and below the melting peak temperature of the mixture. This promotes salting out of the binder resin microparticles, ester compound A microparticles, and other toner component microparticles such as colorant microparticles, while simultaneously promoting fusing. Once the desired particle size is reached, a flocculation inhibitor is added to stop particle growth. Furthermore, heating is continued as needed to control the particle shape.

[0073] In the toner particle formation process, it is preferable to minimize the standing time after adding the flocculant and quickly heat the mixture to a temperature above the glass transition point of the binder resin fine particles and ester compound A fine particles, and below the melting peak temperature of these mixtures. The reason for this is not entirely clear, but it is thought that depending on the standing time after salting out, the aggregation state of the particles may fluctuate, leading to an unstable particle size distribution or fluctuations in the surface properties of the fused particles. The time to raise the temperature is usually preferably within 30 minutes, and more preferably within 10 minutes. Furthermore, the heating rate is preferably 1°C / min or higher. There is no particular upper limit to the heating rate, but from the viewpoint of suppressing the generation of coarse particles due to the rapid progression of fusion, it is preferable to keep it at 15°C / min or lower. In addition, it is important to maintain the temperature of the reaction system for a certain period of time after the reaction system reaches a temperature above the glass transition point to continue the fusion. This allows for effective progression of core particle growth and fusion, and ultimately improves the durability of the toner particles obtained.

[0074] As a flocculant, known metal salts containing divalent or higher metal ions can be used. Details will be described later. When surfactants are used in the toner particle formation process, known surfactants can be used. Details will be described later.

[0075] <Polymerization initiator> When using emulsion polymerization in the resin fine particle dispersion preparation process, any known polymerization initiator can be used without any particular restrictions. Polymerization initiators include hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetraline hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetate-tert-hydroperoxide, tert-butyl performate, tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, and perN-(3-toluyl)palmitate-tert-butylbenzoylperoxa. Examples of peroxide-based polymerization initiators include t-butyl peroxy 2-ethyl hexanoate, t-butyl peroxypivalate, t-butyl peroxyisobutyrate, t-butyl peroxyneodecanoate, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and lauroyl peroxide; and azo-based or diazo-based polymerization initiators include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitride), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile.

[0076] <Surfactants> As surfactants used in the toner particle formation process, known anionic surfactants, cationic surfactants, and nonionic surfactants can be used.

[0077] Examples of anionic surfactants include alkyl sulfate esters such as sodium lauryl sulfate, polyoxyethylene alkyl ether sulfate salts such as sodium polyoxyethylene lauryl ether sulfate, sulfonates such as sodium dodecylbene residue sulfonate and sodium alkylnaphthalene sulfonate, and higher fatty acid salts such as sodium stearate and sodium laurate.

[0078] Cationic surfactants include quaternary ammonium salts such as dodecylammonium bromide, dodecyltrimethylammonium bromide, dodecylpyridinium chloride, dodecylpyridinium bromide, hexadeciyltrimethylanonium bromide, lauryltrimethylammonium chloride, and alkylbenzyldimethylammonium chloride.

[0079] Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether, polyoxyalkylene derivatives such as polyoxyethylene alkylene alkyl ether, sorbitan fatty acid esters such as sorbitan monolaurate and sorbitan monostearate, glycerin fatty acid esters such as glycerol monostearate, and polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate.

[0080] Next, examples of measurement methods used in this specification will be described in detail below. <Method for calculating solubility parameters (SP values)> The SP values ​​of ester compound A (SPw1) and ester compound B (SPw2) of the present invention were determined according to the calculation method proposed by Fedors, as follows. For example, the SP value (SPw1) (J / cm²) of ester compound A. 3 ) 1 / 2When calculating the vapor volume, the evaporation energy (Δei) (J / mol) and molar volume (Δvi) (cm³) are obtained from the table in "Polym.Eng.Sci.,14(2),147-154(1974)" for the atoms or groups of atoms in the molecular structure of the ester compound. 3 Determine the value of ( / mol) and calculate it using the following formula (8). Equation (8): SPw1 = (ΣΔei / ΣΔvi) 1 / 2

[0081] The SP value, SPb, of the styrene-acrylic resin of the present invention was determined according to the calculation method proposed by Fedors, as follows. First, the SP value of the repeating units constituting the styrene-acrylic resin is determined as follows. Here, the repeating units constituting the styrene-acrylic resin refer to the molecular structure in which the double bond of the styrene-acrylic monomer used to obtain the styrene-acrylic resin by polymerization has been cleaved by polymerization. For example, the SP value of a repeating unit (σ m )(J / cm 3 ) 1 / 2 When calculating this, for each atom or group of atoms in the molecular structure of the repeating unit, the evaporation energy (Δei) (J / mol) and molar volume (Δvi) (cm³) are taken from the table in "Polym.Eng.Sci.,14(2),147-154(1974)". 3 Determine the value of ( / mol) and calculate it using the following formula (9). Equation (9): σ m =(ΣΔei / ΣΔvi) 1 / 2

[0082] The SP value (SPb) of a styrene-acrylic resin is calculated by determining the evaporation energy (Δei) and molar volume (Δvi) of each repeating unit that makes up the resin. Then, the product of the product of each repeating unit and its molar ratio (j) in the resin is calculated, and the sum of the evaporation energies of each repeating unit is divided by the sum of the molar volumes to obtain the SP value, which is then calculated using the following formula (10). Equation (10): σ p={(Σj×ΣΔei) / (Σj×ΣΔvi)} 1 / 2 For example, assuming that the resin is composed of two types of repeating units, X and Y, and if the composition ratio of each repeating unit is Wx and Wy (mass%), the molecular weights are Mx and My, the evaporation energies are Δei(X) and Δei(Y), and the molar volumes are Δvi(X) and Δvi(Y), then the molar ratio (j) of each repeating unit will be Wx / Mx and Wy / My, respectively, and the solubility parameter value (σ) of this resin will be p ) is given by equation (11) below. Equation (11): σ p =[{(Wx / Mx)×Δei(X)+Wy / My×Δei(Y)} / {(Wx / Mx)×Δvi(X)+Wy / My×Δvi(Y)}] 1 / 2 Furthermore, if two or more types of resin are mixed, the SP value (σ) of the mixture M The product of the mass composition ratio (Wi) of the mixture and the SP value (σi) of each resin is given by the following formula (12). Equation (12): σ M =Σ(Wi×σi)

[0083] <Method for separating binder resin and ester compounds from toner> The toner is dissolved in tetrahydrofuran (THF), and the solvent is removed from the resulting soluble matter under reduced pressure to obtain the tetrahydrofuran (THF) soluble component of the toner. The obtained tetrahydrofuran (THF) soluble component of the toner is dissolved in chloroform to prepare a sample solution with a concentration of 25 mg / ml. 3.5 ml of the obtained sample solution is poured into the following apparatus, and under the conditions shown below, the low molecular weight component derived from the release agent (molecular weight less than 2000) and the high molecular weight component derived from the binder resin (molecular weight 2000 or more) are separated. Preparative GPC device: Preparative HPLC (product name: LC-980 model, manufactured by Nippon Analytical Industry Co., Ltd.) Preparative columns: JAIGEL 3H, JAIGEL 5H (manufactured by Nippon Analytical Industry Co., Ltd.) Eluent: Chloroform Flow rate: 3.5mL / min After separation, the solvent is removed by distillation under reduced pressure, and the mixture is further dried under reduced pressure in a 90°C atmosphere for 24 hours.

[0084] <Molecular weight measurement of ester compounds by mass spectrometry> • Separation of ester compounds from toner The molecular weight of ester compounds in toner can be determined by measuring the toner itself, but it is more preferable to measure it after the separation procedure. The toner is dispersed in ethanol, which is a poor solvent for toner, and the temperature is raised to a level above the melting point of the ester compound. Pressure may be applied as needed during this process. This operation causes the ester compound, above its melting point, to melt and be extracted into the ethanol. If pressure is applied in addition to heating, the ester compound can be separated from the toner by solid-liquid separation while maintaining the pressure. Next, the extract is dried and solidified to obtain an ester compound. The obtained ester compounds can be identified and their molecular weight measured by thermal decomposition GC-MS using, for example, the apparatus and measurement conditions shown below. Mass spectrometer: ThermoFisher Scientific ISQ GC system: ThermoFisher Scientific FocusGC Ion source temperature: 250℃ Ionization method: EI Mass range: 50-1000 m / z Column: HP-5MS [30m] Pyrolysis apparatus: JPS-700, manufactured by Nippon Analytical Industry Co., Ltd. A small amount of the ester compound separated by extraction and 1 μL of tetramethylammonium hydroxide (TMAH) are added to a pyrofoil heated to 590°C. The prepared sample is then subjected to pyrolysis GC-MS analysis under the above conditions to obtain peaks for the alcohol and carboxylic acid components derived from the ester compound. At this time, the alcohol and carboxylic acid components are detected as methylated products due to the action of the methylating agent TMAH. By analyzing the obtained peaks and identifying the structure of the ester compound, the molecular weight of the ester compound can be determined.

[0085] Furthermore, when identifying and measuring the molecular weight of ester compounds by direct introduction, this can be done, for example, using the following apparatus and measurement conditions. Mass spectrometer: ThermoFisher Scientific ISQ Ion source temperature: 250℃, Electron energy: 70eV Mass range: 50-1000 m / z (CI) Reagent Gas: Methane (CI) Ionization method: ThermoFisher Scientific Direct Exposure Probe (DEP), 0mA (10 sec) - 10mA / sec - 1000mA (10 sec) The ester compounds separated by the extraction process are placed directly onto the filament portion of the DEP unit and measured. The molecular ions of the mass spectra of the principal component peaks around 0.5 to 1 minute of the resulting chromatogram are identified, and the molecular weight is determined.

[0086] <Method for measuring the ester compound content in toner> The ester compound content in the toner can be measured using a thermal analyzer (product name: DSC Q2000, manufactured by TA Instruments Japan Co., Ltd.). Approximately 5.0 mg of toner sample is placed in an aluminum pan (KIT NO. 0219-0041) sample container, the container is placed on a holder unit, and set in an electric furnace. Under a nitrogen atmosphere, the sample is heated from 30°C to 200°C at a heating rate of 10°C / min, and the DSC curve is measured using a differential scanning calorimeter (DSC) to calculate the endothermic amount of the ester compound in the toner sample. The endothermic amount is also calculated using the same method with approximately 5.0 mg of a single ester compound sample. Then, using the endothermic amounts of the ester compounds obtained from each measurement, the wax content is determined by the following formula. Toner content (mass%) = (Endothermic heat absorption of ester compounds in toner sample (J / g)) / (Endothermic heat absorption of individual ester compounds (J / g)) × 100

[0087] <Compositional analysis of the binding resin> • Method for separating the binder resin from the toner Dissolve 100 mg of toner in 3 mL of chloroform. Then, remove insoluble matter by aspirating and filtering using a syringe fitted with a sample processing filter (pore size 0.2 μm to 0.5 μm, for example, a Myshori Disc H-25-2 (manufactured by Tosoh Corporation)). The chloroform-soluble components obtained above are introduced into a preparative HPLC (apparatus: LC-9130 NEXT manufactured by Nippon Analytical Industry Co., Ltd., preparative column (60 cm), exclusion limits: 20000, 70000, 2 columns linked together), and chloroform is used as the eluent. Once peaks are confirmed on the resulting chromatograph, fractions with retention times of 2000 or more molecular weight using monodisperse polystyrene standard samples are separated. The solution of the obtained fractions is dried and solidified to obtain a binder resin.

[0088] • Measurement of composition ratio and weight ratio by nuclear magnetic resonance spectroscopy (NMR) 20 mg of toner is mixed with 1 mL of deuterated chloroform, and the NMR spectrum of the protons in the dissolved binder resin is measured. From the obtained NMR spectrum, the molar ratio and weight ratio of each monomer can be calculated, and the content of units derived from styrene can be determined. For example, in the case of a styrene-acrylic copolymer, the composition ratio and weight ratio can be calculated based on the peak around 6.5 ppm derived from the styrene monomer and the peak around 3.5-4.0 ppm derived from the acrylic monomer. The following apparatus and measurement conditions can be used for nuclear magnetic resonance spectroscopy (NMR). NMR spectrometer: RESONANCE ECX500, manufactured by JEOL Ltd. Observed nucleus: proton Measurement mode: Single pulse

[0089] <Method for measuring the glass transition temperature (Tg) of styrene-acrylic resins> The glass transition temperature (Tg) of the binder resin is measured according to ASTM D3418-82 using a differential scanning calorimetry analyzer (product name: Q1000, TA Instruments). The temperature correction of the instrument's detection unit uses the melting points of indium and zinc, and the heat correction uses the heat of fusion of indium. Specifically, 5 mg of styrene-acrylic resin is accurately weighed and placed in an aluminum pan, with an empty aluminum pan used as a reference. Measurements are taken within the measurement range of 30 to 200°C at a heating rate of 1°C / min. During this heating process, a change in specific heat is obtained in the temperature range of 40°C to 100°C. The intersection point of the line midway between the baseline before and after the specific heat change and the differential heat curve is defined as the glass transition temperature (Tg) of the styrene-acrylic resin.

[0090] <Method for measuring the average circularity of toner and toner particles> The average circularity of toner and toner particles is measured and analyzed using a flow-type particle image analyzer (product name: FPIA-3000, manufactured by Sysmex Corporation) under the following conditions. The specific measurement method is as follows: First, 20 ml of deionized water, from which impurities and other solids have been removed, is placed in a glass container. To this, 0.2 ml of a diluted solution of (product name: Contaminon N, manufactured by Wako Pure Chemical Industries, Ltd.: a 10% by mass aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments consisting of a nonionic surfactant, anionic surfactant, and organic builder) is added, diluted three times by mass with deionized water, as a dispersant. Furthermore, 0.02 g of the sample to be measured is added, and the mixture is dispersed for 2 minutes using an ultrasonic disperser to obtain the dispersion for measurement. During this process, the dispersion is cooled as appropriate so that its temperature is between 10°C and 40°C. As the ultrasonic disperser, a tabletop ultrasonic cleaner disperser with an oscillation frequency of 50 kHz and an electrical output of 150 W (for example, "VS-150" (manufactured by Velvo-Clear)) is used, and a predetermined amount of deionized water is placed in the water tank, to which approximately 2 ml of the aforementioned Contaminon N is added.

[0091] For the measurement, a flow-type particle image analyzer equipped with a "UPlanApro" objective lens (magnification 10x, numerical aperture 0.40) was used, and a particle sheath (product name: PSE-900A, manufactured by Sysmex Corporation) was used as the sheath solution. The dispersion solution prepared according to the above procedure was introduced into the flow-type particle image analyzer, and 3000 toner particles were measured in HPF measurement mode and total count mode. Then, the binarization threshold for particle analysis was set to 85%, and the analyzed particle size was limited to a circular equivalent diameter of 1.985 μm or more and less than 39.69 μm, and the average circularity of the toner and toner particles was determined.

[0092] Before starting the measurement, autofocus adjustment is performed using standard latex particles (for example, Duke Scientific's "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A" diluted with deionized water).

[0093] <Method for measuring weight-average particle size (D4)> The weight-average particle size (D4) of the toner particles is calculated as follows: The measuring device used is a precision particle size distribution analyzer using the pore electrical resistance method equipped with a 100 μm aperture tube (product name: Coulter Counter Multisizer 3®, manufactured by Beckman Coulter, Inc.). Setting the measurement conditions and analyzing the measurement data are done using the included dedicated software (product name: Beckman Coulter Multisizer 3 Version 3.51, manufactured by Beckman Coulter, Inc.). The measurement is performed with an effective measurement channel count of 25,000. The electrolytic aqueous solution used for measurement is prepared by dissolving special grade sodium chloride in deionized water to a concentration of 1.0%, for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.).

[0094] Before performing measurements and analysis, configure the dedicated software as follows. In the dedicated software's "Change Standard Measurement Method (SOMME)" screen, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (manufactured by Beckman Coulter, Inc.). Press the "Measure Threshold / Noise Level Button" to automatically set the threshold and noise level. Also, set the current to 1,600 μA, the gain to 2, the electrolyte to ISOTON II, and check "Flush aperture tube after measurement". In the dedicated software's "Pulse to Particle Size Conversion Settings" screen, set the bin spacing to logarithmic particle size, the particle size bins to 256 particle size bins, and the particle size range from 2 μm to 60 μm.

[0095] The specific measurement method is as follows: (1) Place 200.0 mL of electrolytic solution into a 250 mL round-bottom glass beaker specifically designed for the Multisizer 3, set it on the sample stand, and stir the mixture with the stirrer rod at 24 revolutions per second in a counterclockwise direction. Then, use the "Aperture Tube Flash" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube.

[0096] (2) Place 30.0 mL of the electrolytic solution into a 100 mL flat-bottomed glass beaker. Add 0.3 mL of a diluted solution of "Contaminon N" (a 10% aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted three times by mass with deionized water as a dispersant.

[0097] (3) Prepare an "Ultrasonic Dispersion System Tetra150" (manufactured by Nikko Bios Co., Ltd.) with an electrical output of 120W, which incorporates two oscillators with an oscillation frequency of 50kHz, with their phases shifted by 180 degrees. Add 3.3L of deionized water to the water tank of the ultrasonic disperser, and add 2.0mL of Contaminon N to this water tank.

[0098] (4) Place the beaker from (2) above into the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution inside the beaker is maximized.

[0099] (5) While irradiating the electrolytic aqueous solution in the beaker described in (4) above with ultrasound, add 10 mg of toner particles to the electrolytic aqueous solution in small amounts and disperse them. Continue the ultrasonic dispersion treatment for another 60 seconds. During ultrasonic dispersion, adjust the water temperature in the tank to be between 10°C and 40°C as appropriate.

[0100] (6) Using a pipette, add the electrolytic aqueous solution (5) containing the dispersed toner particles to the round-bottom beaker (1) placed in the sample stand, adjusting the concentration to 5%. Continue measuring until the number of particles reaches 50,000.

[0101] (7) The measurement data is analyzed using the dedicated software provided with the device, and the weight-average particle size (D4) is calculated. Note that the "Average Diameter" on the "Analysis / Volume Statistics (Arithmetic Mean)" screen when the dedicated software is set to Graph / Volume % is the weight-average particle size (D4). [Examples]

[0102] In the following examples, the number of parts is based on parts by mass. <Example of resin particle dispersion preparation process> <Preparation of Resin Microparticle Dispersion 1> • Styrene 81.0 parts n-butyl acrylate 13.0 parts • Lauryl acrylate 6.0 parts • 3.2 parts n-lauryl mercaptan The above materials were mixed and dissolved. To this solution, an aqueous solution of 1.5 parts Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) dissolved in 150 parts ion-exchanged water was added and dispersed. Furthermore, while slowly stirring for 10 minutes, an aqueous solution of 0.3 parts potassium persulfate dissolved in 10 parts ion-exchanged water was added. After purging the system with nitrogen, emulsion polymerization was carried out at 70°C for 6 hours. After polymerization was complete, the reaction solution was cooled to room temperature and ion-exchanged water was added to obtain resin fine particle dispersion 1 with a solid content concentration of 20.0% by mass and a median diameter by volume of 0.2 μm. The SP value (SPb) of the obtained styrene-acrylic resin was 20.00 (J / cm²). 3 ) 1 / 2 The glass transition temperature (Tg) was 56°C.

[0103] <Preparation of resin particle dispersions 2-11> Resin fine particle dispersions 2 to 11 were obtained in the same manner as the production example of resin fine particle dispersion 1, except that the materials used were changed as shown in Table 1 below.

[0104] [Table 1] In Table 1, St represents styrene, n-BA represents n-butyl acrylate, LA represents lauryl acrylate, n-OA represents n-octyl acrylate, n-DA represents n-decyl acrylate, MA represents myristyl acrylate, and PA represents palmityl acrylate. The numerical values ​​for these compounds represent parts.

[0105] <Example of preparation steps for ester compound A dispersion> <Preparation of Ester Compound A Dispersion 1> Pentaerythritol tetrabehenate 100.0 parts • Neogen RK 15.0 • Ion-exchanged water 385.0 parts The above materials were mixed and dispersed for approximately 1 hour using a wet jet mill (product name: JN100, manufactured by Jokoh Co., Ltd.) to obtain ester compound A dispersion 1. The concentration of ester compound A dispersion 1 was 20% by mass.

[0106] <Preparation of Ester Compound A Dispersion 2-6> Ester compound A dispersions 2 to 6 were obtained in the same manner as the preparation example of ester compound A dispersion 1, except that the materials used were changed as shown in Table 2 below. The concentration of all dispersions was 20% by mass.

[0107] [Table 2]

[0108] <Preparation of Ester Compound B Dispersions 1-5> Ester compound B dispersions 1 to 5 were obtained in the same manner as the preparation example of ester compound A dispersion 1, except that the materials used were changed as shown in Table 2 below. The dispersion concentration for all was 20% by mass.

[0109] [Table 3]

[0110] <Example of preparation of paraffin wax dispersion> In the example of the preparation of ester compound A dispersion 1, the paraffin wax dispersion was prepared in the same manner as in the example of the preparation of ester compound A dispersion 1, except that pentaerythritol tetrastearate was replaced with HNP-51 (manufactured by Nippon Seiro Co., Ltd.).

[0111] <Example of preparation of a colorant dispersion> As a coloring agent, 100.0 parts of carbon black (product name: Nipex35, manufactured by Orion Engineered Carbons) and 15 parts of Neogen RK were mixed with 885.0 parts of deionized water, and the mixture was dispersed for approximately 1 hour using a wet jet mill (product name: JN100, manufactured by Jokoh Co., Ltd.) to obtain a coloring agent dispersion.

[0112] <Example of toner particle formation process> <Example of toner particle 1 formation> ·Resin particle dispersion 1 100.0 parts • 1 8.0 parts of ester compound A dispersion • Ester compound B dispersion 1 12.0 parts • Colorant dispersion 8.0 parts Using a homogenizer (product name: Ultra-Turrax T50, manufactured by IKA), the above materials were stirred while the temperature inside the container was adjusted to 30°C, and a 1 mol / L sodium hydroxide aqueous solution was added to adjust the pH of the dispersion to 8.0. As a coagulant, an aqueous solution of 0.3 parts magnesium sulfate dissolved in 10 parts deionized water was added to the dispersion over 10 minutes while stirring at 30°C. After standing for 3 minutes, the temperature was raised to 60°C to generate associated particles. In this state, the particle size of the associated particles was measured using a "Coulter Counter Multisizer 3" (manufactured by Beckman Coulter). When the weight-average particle size (D4) of the associated particles reached 6.5 μm, 0.9 parts sodium chloride and 5.0 parts Neogen RK were added to stop particle growth and obtain toner particle dispersion 1.

[0113] Hydrochloric acid was added to the obtained toner particle dispersion 1 to adjust the pH of the dispersion to 1.5 or less, and after stirring and letting it stand for 1 hour, solid-liquid separation was performed using a pressure filter to obtain toner cake. This was re-slurred with deionized water to become a dispersion again, and then solid-liquid separation was performed using a pressure filter. The re-slurrying and solid-liquid separation were repeated until the electrical conductivity of the filtrate was 5.0 μS / cm or less, and finally solid-liquid separation was performed to obtain toner cake. The obtained toner cake was dried using an airflow dryer, a flash jet dryer (manufactured by Seishin Corporation). The drying conditions were an inlet temperature of 90°C, a dryer outlet temperature of 40°C, and the toner cake supply rate was adjusted according to the moisture content of the toner cake so that the outlet temperature did not deviate from 40°C. Furthermore, fine and coarse powder was cut using a multi-partition classifier utilizing the Coanda effect to obtain toner particles 1. When the weight-average particle size (D4) and average circularity of toner particle 1 were measured using the method described above, the weight-average particle size (D4) was 6.5 μm and the average circularity was 0.965.

[0114] <Examples of toner particle formation 2-18 and 20-27> In the example of toner particle 1 formation, toner particles 2-18 and 20-27 were formed in the same manner as in the example of toner particle 1 formation, except that the materials used were changed to those listed in Table 4. In the example of toner particle 18 formation, the associated particles were generated by raising the temperature to 75°C. The weight-average particle size (D4) and average circularity of toner particles 2-18 and 20-27 were measured using the method described above. The weight-average particle size (D4) of toner particles 2-17 and 20-27 was 6.5 μm, and the average circularity was 0.965. The weight-average particle size (D4) of toner particle 18 was 6.5 μm, and the average circularity was 0.980.

[0115] [Table 4]

[0116] <Example of toner particle 19 formation> Toner particles 19 were prepared using a grinding method as follows. • Binding resin: Styrene / n-butyl acrylate / lauryl acrylate copolymer (Styrene:n-butyl acrylate:lauryl acrylate mass ratio of 81:13:6, Tg=56℃): 100.0 parts • Carbon black (product name: Nipex35, manufactured by Orion Engineered Carbons): 8.0 parts • Ester compound A (dipentaerythritol hexabenate, melting point 87°C): 8.0 parts • Ester compound B (ethylene glycol distearate): 12.0 parts The above materials were pre-mixed in an FM mixer (manufactured by Nippon Coke Industries Co., Ltd.), and then melt-kneaded in a twin-screw kneader (product name: PCM-30, manufactured by Ikegai Iron Works Co., Ltd.) to obtain a compound. The obtained compound was cooled, coarsely ground in a hammer mill (manufactured by Hosokawa Micron Corporation), and then ground in a mechanical pulverizer (product name: T-250, manufactured by Turbo Industries Co., Ltd.) to obtain a fine powder. The obtained fine powder was classified using a multi-part classifier utilizing the Coanda effect (product name: EJ-L-3, manufactured by Nippon Steel Mining Co., Ltd.) to obtain toner particles 19. The weight-average particle size (D4) of the toner particles 19 was 6.5 μm. When the average circularity of the toner particles 19 was measured using the method described above, the average circularity of the toner particles 19 was found to be 0.940.

[0117] <Example of toner particle 28 formation> The toner particles 28 were formed based on the example described in Patent Document 1. Details are shown below. (1) Preparation of dispersion of resin fine particles for core (First stage polymerization) In a reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device, 4 parts of sodium polyoxyethylene(2) dodecyl ether sulfate and 3000 parts of deionized water were charged, and the internal temperature was raised to 80°C while stirring at a stirring speed of 230 rpm under a nitrogen flow. After raising the temperature, 10 parts of potassium persulfate dissolved in 200 parts of deionized water was added to bring the liquid temperature to 75°C, and a monomer mixture consisting of 68 parts of styrene, 164 parts of n-butyl acrylate, and 68 parts of methacrylic acid was added dropwise over 1 hour. Polymerization was carried out by heating and stirring at 75°C for 2 hours, and a dispersion of resin fine particles b1 was prepared.

[0118] (Second stage polymerization) A reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device was charged with a solution prepared by dissolving 2 parts of sodium polyoxyethylene(2) dodecyl ether sulfate in 3000 parts of deionized water. 42 parts (solid content) of a dispersion of resin fine particles b1, heated to 80°C, 70 parts of pentaerythritol tetrabehenate, and 70 parts of ethylene glycol distearate were added to a monomer solution consisting of 195 parts styrene, 91 parts n-butyl acrylate, 20 parts methacrylic acid, and 3 parts n-octyl mercaptan, which were dissolved at 80°C. The mixture was then mixed and dispersed for 1 hour using a mechanical disperser (product name: CLEARMIX, manufactured by M-Technique Co., Ltd.) to prepare a dispersion containing emulsion particles (oil droplets). Next, an initiator solution prepared by dissolving 5 parts potassium persulfate in 100 parts deionized water was added to this dispersion, and polymerization was carried out by heating and stirring the system at 80°C for 1 hour to prepare a dispersion of resin fine particles b2.

[0119] (Third stage polymerization) To the dispersion of resin fine particles b2 described above, a solution of 10 parts potassium persulfate dissolved in 200 parts deionized water was added, and a monomer mixture consisting of 298 parts styrene, 137 parts n-butyl acrylate, 50 parts n-stearyl acrylate, 64 parts methacrylic acid, and 6 parts n-octyl mercaptan was added dropwise over 1 hour under a temperature of 80°C. After the dropwise addition was complete, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28°C to obtain a dispersion of core resin fine particles C1.

[0120] (2) Preparation of dispersion of resin microparticles for shells A surfactant solution, prepared by dissolving 2.0 parts of sodium polyoxyethylene dodecyl ether sulfate in 3000 parts of deionized water, was placed in a reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device. The internal temperature was raised to 80°C while stirring at a rate of 230 rpm under a nitrogen atmosphere. To this solution, an initiator solution prepared by dissolving 10 parts potassium persulfate in 200 parts deionized water was added, and a polymerizable monomer mixture consisting of 564 parts styrene, 140 parts n-butyl acrylate, 96 parts methacrylic acid, and 12 parts n-octyl mercaptan was added dropwise over 3 hours. After the addition, the system was heated and stirred at 80°C for 1 hour to carry out polymerization, thereby obtaining a dispersion of shell resin fine particles S1.

[0121] (3) Preparation of a dispersion of colorant fine particles 90 parts of sodium dodecyl sulfate were dissolved by stirring in 1600 parts of deionized water. While stirring this solution, 420 parts of carbon black (product name: Regal 330R, manufactured by Cabot Corporation) were gradually added, and then the mixture was dispersed using a stirring device (product name: Creamix, manufactured by M-Technique Co., Ltd.) to prepare a dispersion of colorant fine particles, Bk. The particle size of the colorant microparticles in the dispersion Bk of these colorant microparticles was measured using an electrophoretic light scattering photometer (product name: ELS-800, manufactured by Otsuka Electronics Co., Ltd.) and was found to be 110 nm.

[0122] (4) Formation of toner particles (Agglomeration / fusion process) In a 5L reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device, 360 parts (solid content equivalent) of a dispersion of core resin microparticles C1, 1100 parts of deionized water, and 200 parts of a dispersion of coloring agent microparticles Bk were charged. After adjusting the liquid temperature to 30°C, a 5N sodium hydroxide aqueous solution was added to adjust the pH to 10. Next, an aqueous solution of 60 parts magnesium chloride dissolved in 60 parts deionized water was added over 10 minutes at 30°C under stirring. After holding for 3 minutes, the temperature was raised, and the system was heated to 85°C over 60 minutes, and the particle growth reaction was continued while maintaining the temperature at 85°C. In this state, the particle size of the associated particles was measured using a "Coulter Multisizer 3" (manufactured by Beckman Coulter). When the volume-based median diameter reached 6 μm, an aqueous solution of 40 parts sodium chloride dissolved in 160 parts deionized water was added to stop particle growth. Furthermore, as a maturation process, the mixture was heated and stirred at a liquid temperature of 80°C for 1 hour to promote fusion between particles, thereby forming core particle 1.

[0123] (Shering process) Next, 40 parts (in terms of solid content) of a dispersion of shell resin fine particles S1 were added, and stirring was continued at 80°C for 1 hour to fuse the shell resin fine particles S1 to the surface of core particle 1 and form a shell layer. At this point, an aqueous solution of 150 parts sodium chloride dissolved in 600 parts deionized water was added, and a maturation treatment was performed at 80°C. The average circularity of the toner particles was measured during the maturation treatment, and when the desired average circularity was achieved, it was cooled to 30°C.

[0124] (Washing and drying process) The generated particles were subjected to solid-liquid separation using a basket-type centrifuge (product name: MARKIII, model number 60×40, manufactured by Matsumoto Machinery Co., Ltd.) to form a wet cake of toner particles. This wet cake was washed with ion-exchanged water at 40°C using the basket-type centrifuge until the electrical conductivity of the filtrate was 5 μS / cm, and then dried using a "Flash Jet Dryer" (manufactured by Seishin Enterprise Co., Ltd.) until the moisture content was 0.5% by mass to obtain toner particles 28. When the weight-average particle size (D4) and average circularity of the toner particles 28 were measured using the method described above, the weight-average particle size (D4) was 6.5 μm and the average circularity was 0.965.

[0125] <Example of toner particle formation 29> The toner particles 29 were formed based on the example described in Patent Document 2. Details are shown below.

[0126] (1) Manufacturing of binder resin for toner To 200 parts of deionized water, 0.2 parts of polyvinyl alcohol (PVA235, manufactured by Kuraray) was added as a dispersant. To this, 100 parts of monomer components consisting of 84.3 parts of styrene, 14.9 parts of lauryl methacrylate, 0.5 parts of 1,6-hexanediol diacrylate, and 0.3 parts of trimethylolpropane trimethacrylate were added, along with 3 parts of benzoyl peroxide as a polymerization initiator, to form a dispersion. To this dispersion, 9.9 parts of Fischer-Tropsch wax were added to 100 parts of vinyl copolymer formed by copolymerization of the monomer components. Suspension polymerization was carried out at 125°C for 4 hours, followed by cooling. Before cooling, a 25% sodium hydroxide aqueous solution was added to the dispersion to a volume of 2%, raising the pH of the solution to 5.5 or higher and neutralizing the benzoic acid residue of the polymerization initiator. Subsequently, the resin particles were filtered off to obtain a binder resin for toner.

[0127] (2) Manufacturing of toner particles 95 parts of the obtained toner binder resin, 5 parts of a coloring agent (product name: Carbon Black MA-100, manufactured by Mitsubishi Chemical), and 1 part of a charge control agent (product name: Bontron S-34, manufactured by Orient Chemical) were mixed in a small pulverizer and kneaded at 90°C for 10 minutes using a Laboplast Mill (manufactured by Toyo Seiki Seisakusho, capacity 100 ml, rotation speed 70 rpm). After that, the kneaded material was cooled to room temperature, pulverized using a LabJet Mill (manufactured by Nippon Pneumatic), and classified using an air classifier (manufactured by Nippon Pneumatic) to obtain toner with a weight-average particle size (D4) of 8.0 μm. When the average circularity of the toner particles 29 was measured using the method described above, the average circularity of the toner particles 29 was found to be 0.940.

[0128] <Examples of toner manufacturing> <Manufacturing of Toner 1> • Toner particles 1 100 copies • Hydrophobic silica 1.5 parts • Hydrotalcite (Product name: DHT-4A: Manufactured by Kyowa Chemical Industry Co., Ltd.) 0.3 parts The above materials were mixed and stirred at 3000 rpm for 10 minutes using an FM mixer (manufactured by Nippon Coke Industries). Toner 1 was then obtained by passing the mixture through a 200-mesh sieve. The obtained toner was analyzed according to the following methods: <Method for separating binder resin and ester compound from toner>, <Molecular weight measurement of ester compound by mass spectrometry>, <Method for measuring the ester compound content in toner>, <Compositional analysis of binder resin>, and <Method for measuring the average circularity of toner and toner particles>. As a result, the relative abundance of the unit shown in formula (1), ester compound A, and ester compound B in the toner was the same as the ratio in which they were added. The physical properties of Toner 1 are shown in Table 5.

[0129] <Manufacturing of toners 2-18 and 21-24> In the manufacturing example of toner 1, toners 2-18 and 21-24 were obtained in the same manner as in the manufacturing example of toner 1, except that toner particle 1 was changed to toner particles 2-18 and toner particles 20-23. The obtained toners were analyzed according to <Method for separating binder resin and ester compound from toner>, <Molecular weight measurement of ester compound by mass spectrometry>, <Method for measuring the content of ester compound in toner>, <Compositional analysis of binder resin>, and <Method for measuring the average circularity of toner and toner particles>. As a result, the abundance ratio of the unit shown in formula (1), ester compound A, and ester compound B in the toner was the same as the ratio in which they were added. The physical properties of toners 2-18 and 21-24 are shown in Table 5.

[0130] <Manufacturing of Toner 19> • Toner particles 2, 100 copies • Hydrophobic silica 1.5 parts The above materials were mixed and stirred at 3000 rpm for 10 minutes using an FM mixer (manufactured by Nippon Coke Industries). Toner 19 was then obtained by passing the mixture through a 200-mesh sieve. The obtained toner was analyzed according to the following methods: <Method for separating binder resin and ester compound from toner>, <Molecular weight measurement of ester compound by mass spectrometry>, <Method for measuring the ester compound content in toner>, <Compositional analysis of binder resin>, and <Method for measuring the average circularity of toner and toner particles>. As a result, the relative abundance of the unit shown in formula (1), ester compound A, and ester compound B in the toner was the same as the ratio in which they were added. The physical properties of toner 19 are shown in Table 5.

[0131] <Manufacturing of Toner 20 and Toner 25-30> In the manufacturing example of toner 19, toners 20 and 25-30 were obtained in the same manner as in the manufacturing example of toner 19, except that toner particle 2 was replaced with toner particles 19 and 24-29. The obtained toners were analyzed according to the following methods: <Method for separating binder resin and ester compound from toner>, <Molecular weight measurement of ester compound by mass spectrometry>, <Method for measuring the ester compound content in toner>, <Compositional analysis of binder resin>, and <Method for measuring the average circularity of toner and toner particles>. As a result, the relative abundance of the unit shown in formula (1), ester compound A, and ester compound B in the toner was the same as the ratio in which they were added. Table 5 shows the physical properties of toner 20 and toners 25-30.

[0132] [Table 5]

[0133] In Table 5, under the "Binding Resin" column, "Y" indicates that the binding resin contains the unit shown in formula (1), and "N" indicates that the binding resin does not contain the unit shown in formula (1). Also, under the "Ester Compound A" and "Ester Compound B" columns, "Formula (2)" to "Formula (6)" refer to the compounds shown in formulas (2) to (6), respectively. "Y" indicates that the compounds shown in formulas (2) to (6) are included, and "N" indicates that the compounds shown in formulas (2) to (6) are not included. "Ratio of Formula (1)" indicates the ratio of the mass of the unit shown in formula (1) to the mass of the binding resin. Under the "Hydrotalcite" column, "Y" indicates that the toner contains hydrotalcite as an external additive, and "N" indicates that the toner does not contain hydrotalcite.

[0134] [Examples, Comparative Examples] Evaluations were conducted using toners 1-30 in the combinations shown in Table 6. The evaluation results are shown in Table 6. Examples 19 and 20 are provided for reference only. The evaluation method and evaluation criteria of the present invention are described below. As the image forming apparatus, a commercially available laser printer, the LBP-712Ci (manufactured by Canon), was modified to have a process speed of 300 mm / sec and variable fuser temperature control, and a commercially available process cartridge, the toner cartridge 040H (black) (manufactured by Canon), was used. The product toner was removed from inside the cartridge, cleaned with compressed air, and then 165 g of the toner of the present invention was filled in. In addition, the product toner was removed from each of the yellow, magenta, and cyan stations, and the yellow, magenta, and cyan cartridges with the toner level detection mechanism disabled were inserted for evaluation. Image gloss was evaluated under normal temperature and humidity conditions (temperature 25.0°C, relative humidity 50%). The fuser temperature was controlled in 5°C increments within a range of 160°C to 280°C, and the media used was gloss paper, specifically BROCHURE PAPER 150g GLOSSY (Hewlett-Packard: 150g / m²). 2 Using this method, 50 solid black images with a print ratio of 100% were output.

[0135] Image gloss was measured at five points in the first image: top left, top right, center, bottom left, and bottom right. The average image gloss value at the point where the average of the five points' image gloss values ​​was highest within the given temperature range was defined as the final image gloss. The temperature control temperature at which the average of the five image gloss values ​​was highest was defined as the fixing temperature. The standard deviation of the five image gloss values ​​was used as an indicator of image gloss uniformity. The evaluation criteria are shown below.

[0136] <Image gloss evaluation> A: Image gloss is 70 or higher B: Image gloss is between 60 and 70 C: Image gloss is between 50 and 60 D: Image gloss is less than 50

[0137] <Evaluation of low-temperature fixation> A: Fixing temperature is 190°C or lower B: Fixing temperature is above 190°C and below 200°C C: Fixing temperature is above 200°C and below 210°C D: Fixing temperature exceeds 210°C

[0138] <Evaluation of image gloss uniformity> A: The standard deviation of the image gross is 1.5 or less. B: The standard deviation of the image gross is greater than 1.5 and less than or equal to 3.0. C: The standard deviation of the image gross is greater than 3.0 and less than or equal to 4.5. D: The standard deviation of the image gross exceeds 4.5.

[0139] Furthermore, the adhesion between the first 50 images at the fixing temperature was checked and used as an indicator of image stacking performance. The evaluation criteria are shown below.

[0140] <Evaluation of image stacking capability> A: Image is not stuck. B: Slight sticking is observed between the 1st and 10th images. C: Slight sticking is observed between the 10th and 20th images. D: Minor sticking is observed from the 20th image onwards.

[0141] Furthermore, the offset state of the trailing edge of the image towards the non-image area was checked in images taken at temperatures up to 10°C higher than the fixing temperature, and this was used as an indicator of release properties. The evaluation criteria are shown below.

[0142] <Evaluation of mold release properties> A: No offset is visible. B: A slight offset is observed in images with a fixing temperature 10°C higher than the actual fixing temperature. C: A slight offset is observed in images with a fixing temperature 5°C higher than the actual fixing temperature. D: A slight offset is visible in the image of the fixing temperature.

[0143] Furthermore, images whose image gloss was confirmed were stored in a low-temperature, low-humidity environment (15°C / 10%RH) for 30 days. After storage, the images were observed using an optical microscope and visual inspection to determine their image preservation capabilities. The evaluation criteria are shown below.

[0144] <Evaluation of image preservation> A: No changes are visible in the image. B: Minor cracks can be seen under an optical microscope, but they are not visible to the naked eye. C: Cracks are visible under an optical microscope, but not visible to the naked eye. D: Cracks are visible to the naked eye.

[0145] [Table 6]

Claims

1. A toner having binder resin and ester compound A in toner particles and an external additive, The binder resin contains a styrene-acrylic resin having a unit represented by the following formula (1), The ester compound A is an ester compound represented by the following formula (2) or formula (3), The external additive contains hydrotalcite, The SP value of the styrene-acrylic resin is SPb (J / cm²). ３ ) １／２ and the SP value of the ester compound A is SPw1 (J / cm²). ３ ) １／２ The absolute value of the difference between the two is between 1.00 and 2.

00. A toner characterized by the following features. 【Chemistry 1】 (In formula (1), R １ R represents a hydrogen atom or a methyl group. ２ (This represents a linear alkyl group having 10 to 14 carbon atoms.) 【Chemistry 2】 【Transformation 3】 (In Formula (2) and Formula (3), R １１ ~R １４ and R ２１ ~R ２６ each independently represents a linear alkyl group having 15 to 21 carbon atoms.)

2. The toner according to claim 1, wherein the styrene-acrylic resin contains 1% by mass or more and 15% by mass or less of the unit represented by formula (1).

3. The toner particles contain ester compound B, The ester compound B is an ester compound represented by the following formula (4), formula (5), or formula (6), The SPb (J / cm ３ ) １／２ and the SP value of the ester compound B is SPw2 (J / cm²). ３ ) １／２ The absolute value of the difference between the two is 2.10 or less. The toner according to claim 1 or 2. 【Chemistry 4】 【Transformation 5】 【Transformation 6】 (In equations (4), (5), and (6), R ３１ and R ４１ Each independently represents an alkylene group having 2 to 8 carbon atoms, R ３２ , R ３３ , R ４２ , R ４３ , R ５１ and R ５２ Each of these independently represents a linear alkyl group having 14 to 24 carbon atoms.

4. The toner according to any one of claims 1 to 3, wherein the ester compound A is an ester compound represented by the following formula (2') or the following formula (3'). 【Transformation 7】 【Transformation 8】 (In equations (2') and (3'), R １１ ~R １４ and R ２１ ~R ２６ Each of these independently represents a linear alkyl group having 17 to 21 carbon atoms.

5. The toner according to claim 4, wherein the ester compound A is an ester compound represented by formula (2').

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