toner

Abstract

To provide a toner that achieves both high image gloss and image loading 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 a specific structure. The ester compound A is an ester compound represented by a specific structure. The absolute value of the difference between the SP value of the styrene-acrylic resin, SPb(J / cm3)1 / 2 and the SP value of the ester compound A, SPw1(J / cm3)1 / 2 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 recording methods utilizing electrophotography, electrostatic recording, and toner jet recording. [Background technology]

[0002] In recent years, the application of electrophotographic image formation has expanded from office use to commercial printing. The image quality required for commercial printing applications is diverse, but in the field of photo printing in particular, high print coverage and high gloss images must be output at high speed. To output high-gloss images at high speed with a high printing rate, the toner is required to have excellent melting properties that allow it to have a sufficiently low viscosity even when heated for a short period of time. In order to meet such demands, various studies have been conducted on binder resins used in toners, including styrene-acrylic resins incorporating long-chain alkyl (meth)acrylates as binder resins with excellent melting properties.

[0003] Patent Document 1 discloses a toner for developing electrostatic images, characterized in that the binder resin contains 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 also contains a crystalline ester compound. It also discloses that pentaerythritol tetrabehenate can be used as a wax. Patent Document 1 uses a styrene-acrylic resin to control the affinity between the crystalline ester compound and the binder resin, thereby improving the melting characteristics of the toner. However, when images with high print rates are continuously output using the toner of Patent Document 1, the images stick to each other, revealing an issue with image buildability. Furthermore, when pentaerythritol tetrabehenate is used as a wax in the toner of Patent Document 1, no improvement in image buildability is observed.

[0004] Meanwhile, Patent Document 2 discloses a binder resin for toners containing a vinyl copolymer obtained by copolymerizing a monomer component containing 10 to 30 mass % of a (meth)acrylic acid alkyl ester monomer having an alkyl group with 8 or more carbon atoms and 0.2 to 2 mass % of an alkyldiol diacrylate monomer having an alkylene group with 6 or more carbon atoms, and Fischer-Tropsch wax. The binder resin disclosed in Patent Document 2 has a crosslinked structure formed by the alkyldiol acrylate monomer having 6 or more carbon atoms, which increases the viscosity of the image surface after fixing, thereby suppressing image sticking. However, the method disclosed in Patent Document 2 has the problem that sufficient image gloss cannot be obtained in a high-speed process.

[0005] As described above, toners using styrene-acrylic resins incorporating long-chain alkyl acrylates as binder resins can produce high image gloss, but they have issues with image loading, and there has been a demand for a toner that can achieve both at a high level. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-035506 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-322477 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a toner that achieves both high image gloss and image loading capacity. [Means for solving the problem]

[0008] The present invention provides a toner having toner particles containing 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 SP value of the styrene-acrylic resin, SPb (J / cm 3 ) 1 / 2 and the SP value of the ester compound A, SPw1 (J / cm 3 ) 1 / 2 The absolute value of the difference between is 1.00 or more and 2.00 or less. The present invention relates to a toner characterized by the above-mentioned. [ka] In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 represents a linear alkyl group having 10 to 14 carbon atoms. [ka] [ka] In formula (2) and formula (3), R 11 ~R 14 and R 21 ~R 26 are each independently a linear alkyl group having 15 to 21 carbon atoms. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a toner that achieves both high image gloss and image loading properties. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the present invention, unless otherwise specified, the description "XXX to XX" representing a numerical range means a numerical range including the lower and upper limits, which are the endpoints.

[0011] The toner of the present invention is a toner having toner particles containing 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 formula (2) or formula (3), The SP value of the styrene-acrylic resin, SPb (J / cm 3 ) 1 / 2 and the SP value of the ester compound A, SPw1 (J / cm 3 ) 1 / 2 The absolute value of the difference between the two is 1.00 or more and 2.00 or less. [ka] In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 represents a linear alkyl group having 10 to 14 carbon atoms. [ka] [ka] In formula (2) and formula (3), R 11 ~R 14 and R 21 ~R 26 are each independently a linear alkyl group having 15 to 21 carbon atoms.

[0012] The reason why the toner of the present invention can achieve both high image gloss and image loading capacity is not clear, but the present inventors speculate as follows. The unit represented by formula (1) (hereinafter also referred to as the "long-chain acrylate moiety") has high molecular chain mobility. Therefore, resins having long-chain acrylate moieties have a high degree of freedom when melted and are easily reduced in viscosity. Therefore, 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 moiety present on the image surface after fixing has high molecular chain mobility, the part that comes into contact with the next printed paper tends to stick to it, which can cause image sticking, especially when outputting at high speed with a high printing rate.

[0013] In general, reducing the mobility of molecular chains is an effective way to prevent image sticking. Specifically, a method of reducing the mobility of molecular chains by crosslinking the main chains of a resin with a crosslinking agent is known.

[0014] However, because resins with long-chain acrylate moieties have high side chain mobility, even if the main chain is crosslinked, the mobility of the side chains does not decrease, and sufficient image buildability may not be achieved. Furthermore, if image sticking is suppressed by crosslinking between the main chains of the resin, the mobility of the molecular chains decreases regardless of the temperature range, which tends to hinder low viscosity during fixing. Therefore, it was found that there is a trade-off between image gloss and image buildability. To resolve this trade-off, it is believed that an effective configuration is one in which the degree of freedom of the molecular chain is high during fixing and decreases after fixing.

[0015] In the present invention, the above-mentioned problems are solved by a toner containing 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 having 10 to 14 carbon atoms, and the ester compound A is an ester compound having 4 to 6 linear alkyl groups having 15 to 21 carbon atoms in the molecule. In addition, the SP value of the styrene-acrylic resin, SPb (J / cm 3 ) 1 / 2 and the SP value of ester compound A, SPw1 (J / cm 3 ) 1 / 2 The absolute value of the difference between is 1.00 or more and 2.00 or less.

[0016] In the above configuration, the affinity between the styrene-acrylic resin and ester compound A is increased by controlling the SP values ​​of the styrene-acrylic resin and ester compound A. Therefore, the linear alkyl group in ester compound A can interact with the linear alkyl group in the long-chain acrylate moiety. Because the linear alkyl groups in the long-chain acrylate moiety and the linear alkyl group in ester compound A have similar structures, at room temperature the linear alkyl groups are oriented to each other, 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, thereby reducing the mobility of the main chain. On the other hand, at high 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, by adopting the configuration of the present invention, the mobility of the linear alkyl groups in the long-chain acrylate moiety is high at high temperatures and low at room temperature. That is, it is possible to control the mobility of the linear alkyl group in the long-chain acrylate moiety by changing the temperature.

[0017] As described above, in the present invention, during fixation at high temperatures, the linear alkyl group in the long-chain acrylate moiety has high mobility, resulting in a low viscosity of the entire resin. This makes it possible to obtain high image gloss. On the other hand, when the temperature is lowered after fixation, the linear alkyl group in the long-chain acrylate moiety aligns with the linear alkyl group in ester compound A, reducing the mobility of both the linear alkyl group and the main chain. This prevents images from sticking together, improving image loading.

[0018] Next, the configuration of the present invention will be described in more detail below. <Binder 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 enables low viscosity during fixing and improves image gloss. In addition, by combining it with the ester compound A described below, image sticking can be suppressed and image loading properties can be improved.

[0020] In formula (1), R 1 is a hydrogen atom or a methyl group. 2 is a linear alkyl group having 10 to 14 carbon atoms. 2 When R is a linear alkyl group, the viscosity of the resin is reduced and it is possible for it to be oriented with the linear alkyl group in the ester compound A. This results in improved image gloss and image loading capacity. Furthermore, if the carbon number is 10 or more, the viscosity of the resin is reduced more easily, and image gloss is improved. If the carbon number is 14 or less, the linear alkyl group in the resin and the linear alkyl group in the ester compound A are oriented preferentially over the alignment of the linear alkyl groups with each other in the resin, improving image loading capacity. 2 It is more preferable that the linear alkyl group represented by the formula (I) has 12 carbon atoms.

[0021] The styrene-acrylic resin is preferably a styrene-acrylic resin having 1% by mass or more and 15% by mass or less of the unit represented by formula (1). When the content of the unit represented by formula (1) is 1% by mass or more and 15% by mass or less, a sufficient viscosity-lowering effect is obtained, thereby improving image gloss. In addition, the orientation of the linear alkyl groups possessed by the long-chain acrylate moiety is suppressed, thereby improving image loading ability. The styrene-acrylic resin is more preferably a styrene-acrylic resin having 2% by mass or more and 10% by mass or less of the unit represented by formula (1).

[0022] The styrene-acrylic resin contains a unit represented by the following formula (7) in addition to the unit represented by formula (1): The styrene-acrylic resin preferably contains the unit represented by 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 represents a hydrogen atom or a methyl group.

[0023] The SP value of styrene-acrylic resin is SPb (J / cm 3 ) 1 / 2 In this case, SPb is preferably 19.50 or more and 20.40 or less, from the viewpoint of easily increasing affinity with the ester compound A described below. It is more preferably 19.80 or more and 20.10 or less. 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 10,000 or more and 500,000 or less. The weight average molecular weight can be controlled by the reaction temperature, the amount of initiator, etc. when producing the styrene-acrylic resin.

[0025] The glass transition temperature of the styrene-acrylic resin is preferably 40° C. or higher and 60° C. or lower. The glass transition temperature can be controlled by the type and amount of units constituting 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, as needed, without any particular restrictions. Examples of binder resins that can be used simultaneously with the styrene-acrylic resin include vinyl resins other than the styrene-acrylic resin, polyester resins, polyurethane resins, and polyamide resins.

[0027] <Polymerizable monomer> The styrene-acrylic resin may 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, it is preferable to use lauryl acrylate or lauryl methacrylate.

[0028] The polymerizable monomers that form the unit of the styrene-acrylic resin represented by formula (7) are styrene and α-methylstyrene, and among these, it is preferable to use styrene.

[0029] The styrene-acrylic resin may have, in addition to the units represented by formula (1) and formula (7), units derived from conventionally known polymerizable monomers without any particular limitation. Examples of polymerizable monomers include monofunctional monomers having one polymerizable unsaturated bond in the molecule, such as acrylic esters (e.g., methyl acrylate, n-butyl acrylate, etc.); methacrylic esters (e.g., methyl methacrylate, 2-hydroxyethyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate); unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid); unsaturated dicarboxylic acids (e.g., maleic acid); unsaturated dicarboxylic anhydrides (e.g., maleic anhydride); nitrile vinyl monomers (e.g., acrylonitrile); halogen-containing vinyl monomers (e.g., vinyl chloride); and nitro vinyl monomers (e.g., nitrostyrene). Examples of polymerizable monomers include 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, acrylic esters or methacrylic esters are preferred, and n-butyl acrylate is even more preferred.

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

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

[0032] The SP value of ester compound A is SPw1 (J / cm 3 ) 1 / 2 When this is the case, the SP value of styrene-acrylic resin, SPb (J / cm 3 ) 1 / 2 and the SP value of ester compound A, SPw1 (J / cm 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 the ester compound A and the styrene-acrylic resin is increased, allowing the ester compound A to interact with the styrene-acrylic resin, thereby improving image buildability. The absolute value of the difference between SPw1 and SPb is more preferably 1.50 or more and 1.90. On the other hand, when the absolute value of the difference between SPw1 and SPb is less than 1.00, the affinity between the ester compound A and the styrene-acrylic resin is too high, so the ester compound A does not separate during fixing, and the effect of reducing viscosity may be insufficient. Furthermore, when the absolute value of the difference between SPw1 and SPb exceeds 2.00, the ester compound A does not interact with the styrene-acrylic resin, making it impossible to obtain the effect of improving image buildability. Therefore, 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 of the ester compound A and the number of ester bonds.

[0033] When the number of carbon atoms in the linear alkyl group of the 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 the ester compound A is oriented with the styrene-acrylic resin before fixing, the orientation is easily released during the temperature rise process during fixing, and the effect of reducing viscosity can be fully achieved. This makes it easier to achieve the effect of improving image gloss. Furthermore, orientation is also more likely to occur during temperature drop, further improving image loading properties. It is more preferable that C1 and C2 satisfy the following formula (a'). 6≦C1-C2≦10 Formula (a')

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

[0036] When ester compound A is an ester compound represented by formula (2') or formula (3'), the ester compound A partially separates during fixation and functions as a release agent, improving the releasability of the image. Furthermore, ester compound A is more preferably an 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 fixation to temperature drop is improved. Therefore, the styrene-acrylic resin can form a more uniform pseudo-crosslinked structure via the ester compound represented by formula (2'). This improves the uniformity of image gloss.

[0037] Examples of the 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 the 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 the ester compound A is preferably 1,000 or more and 2,200 or less, and more preferably 1,200 or more and 2,200 or less. The content of the ester compound A is preferably 1.0 to 20.0 parts by mass, more preferably 2.0 to 15.0 parts by mass, and even more preferably 3.0 to 12.0 parts by mass, relative to 100.0 parts by mass of the binder resin.

[0039] <Ester compound B> The toner particles are represented by the following formula (4), formula (5), or formula (6), and the SPb (J / cm) of the styrene-acrylic resin is 3 ) 1 / 2 and the SP value of ester compound B, SPw2 (J / cm 3 ) 1 / 2It is preferable that the ester compound B contains an ester compound B having an absolute value of the difference between the above and the above of 2.10 or less. [ka] [ka] [ka] In formula (4), formula (5) and formula (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 are each independently a linear alkyl group having 14 to 24 carbon atoms.

[0040] Ester Compound B has high compatibility with styrene-acrylic resins, so it can achieve low viscosity at lower temperatures, resulting in high image gloss even when fixed at lower temperatures.

[0041] Examples of 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, octanediol distearate, octanediol dibehenate, etc. Examples of compounds represented by formula (5) include distearyl succinate, dibehenyl succinate, distearyl adipate, dibehenyl adipate, distearyl suberate, dibehenyl suberate, distearyl sebacate, dibehenyl sebacate, etc. Examples of the compound 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 (5) because it is easy to improve compatibility with styrene-acrylic resins having a unit represented by formula (1). Ester compounds represented by formula (4) or (5) have a linear structure, which allows them to exhibit sharp melting characteristics. Furthermore, the presence of multiple ester bonds in the molecule makes it easy to control the difference in SP value with styrene-acrylic resins. This further enhances the effect of reducing the viscosity of the toner.

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

[0044] SPb (J / cm) of styrene-acrylic resin 3 ) 1 / 2 and the SP value of ester compound B, SPw2 (J / cm 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, ester compound B becomes more compatible with styrene-acrylic resins, making it possible to obtain high image gloss even when fixed at low temperatures. The absolute value of the difference between SPb and SPw2 is more preferably 2.00 or less. SPw2 is preferably 17.90 or more and 18.50 or less from the viewpoint of easily increasing affinity with styrene-acrylic resins, and more preferably 18.00 or more and 18.20 or less.

[0045] Furthermore, SPw2, which is the SP value of ester compound B, is preferably lower than SPw1, which is the SP value of ester compound A. When SPw2 is lower than SPw1, the linear alkyl group in the long-chain acrylate moiety is preferentially oriented toward ester compound A rather than ester compound B during temperature reduction after fixing, making it easier to obtain the effect of improving image loading ability. SPw2 can be controlled by the number of carbon atoms in the linear alkyl group in ester compound B and the number of ester bonds.

[0046] The melting point of the ester compound B is preferably 65°C or higher and 90°C or lower, more preferably 70°C or higher and 85°C or lower. Furthermore, the melting point of ester compound B is preferably lower than that of ester compound A. When the melting point of ester compound B is lower than that of ester compound A, ester compound B melts first during the temperature rise process during fixation, thereby enhancing the effect of reducing viscosity, and the mobility of ester compound A decreases first during the temperature fall process after fixation, thereby enhancing the effect of improving image loading ability.

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

[0048] The content of the ester compound B is preferably 1.0 parts 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, relative to 100.0 parts by mass of the binder resin.

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

[0050] <Coloring agent> The toner particles may contain a colorant, which may be any of conventionally known pigments and dyes of black, yellow, magenta, cyan, and other colors, magnetic materials, and the like, without any particular limitation. Examples of black colorants include black pigments such as carbon black.

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

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

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

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

[0055] The toner can also be made magnetic by adding a magnetic material. In this case, the magnetic material can also serve as a colorant. 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 the colorant, the content of the magnetic material is preferably 30.0 parts by mass or more and 100.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0056] <Charge control agent> The toner particles may contain a charge control agent. As the charge control agent, any known charge control agent can be used without any particular limitation.

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

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

[0059] <External additives> The toner of the present invention may contain external additives. The external additives are not particularly limited and any known external additives can be used. Examples of external additives include raw silica microparticles such as wet-process silica and dry-process silica, or surface-treated silica microparticles obtained by surface-treating such raw silica microparticles with a treating agent such as a silane coupling agent, a titanium coupling agent, or silicone oil; metal oxide microparticles such as titanium oxide microparticles, aluminum oxide microparticles, and zinc oxide microparticles, or metal oxide microparticles 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 microparticles such as vinylidene fluoride microparticles and polytetrafluoroethylene microparticles.

[0060] Among these, it is preferable to use clay minerals, such as hydrotalcite. Clay minerals have high water retention properties, so their presence on the surface of a fixed image can suppress deterioration due to drying of the image surface, which is particularly noticeable in images with high printing rates. This effect is particularly easily achieved when a highly hydrophobic resin, such as the styrene-acrylic resin of the present invention, is used as the binder resin.

[0061] From the viewpoint of fluidity and charging stability, it is preferable to use silica fine particles obtained by treating the original silica fine particles 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 with respect to 100 parts by mass of the toner particles.

[0063] <Average circularity of toner> The average circularity of the toner is preferably 0.940 or more and 0.995 or less. When the average circularity of the toner is in this range, the surface of the image after fixing tends to be smooth, and the gloss of the fixed image is further improved. The average circularity of the toner is more preferably 0.950 or more and 0.995 or less. 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. <Production of toner particles> The toner particles of the present invention can be produced by known means, such as a kneading and pulverization method or a wet production method. From the viewpoint of uniform particle size and shape controllability, a wet production method is preferably used. Further examples of the wet production method include a suspension polymerization method, a solution suspension method, and an emulsion aggregation method. The emulsion aggregation method is preferably used because it can enhance the dispersion state of the ester compound A.

[0065] A specific example of the production of the toner particles of the present invention by the emulsion aggregation method includes a production example having the following steps (1) and (2). (1) a resin particle dispersion preparation step of forming binder resin particles for core particles by polymerization in an aqueous medium using a binder resin to prepare a dispersion in which the binder resin particles are dispersed; (2) A toner particle forming step in which binder resin particles are aggregated in an aqueous medium to form toner particles.

[0066] Steps (1) and (2) are described in detail below. (1) Resin particle dispersion preparation process In the resin particle dispersion preparation step, binder resin particles are formed, and these are then subjected to the toner particle formation step. Specifically, binder resin microparticles are prepared by adding a monomer solution containing a surfactant-containing aqueous medium, in which a polymerizable monomer and ester compound A for forming the binder resin, and optionally internal additives such as ester compound B, a release agent, and a charge control agent, are dissolved or dispersed. Mechanical energy is applied to the monomer solution to form droplets, and a water-soluble radical polymerization initiator is then added to cause a polymerization reaction in the monomer solution droplets. An oil-soluble polymerization initiator may also be contained in the monomer solution droplets. In this polymerization of the binder resin, a forced emulsification process may be performed by applying mechanical energy. Examples of means for applying such mechanical energy include a homomixer, ultrasonic waves, or other means for applying strong stirring or ultrasonic vibration energy. When polyester resin microparticles are used as the binder resin microparticles, it is preferable to synthesize a polyester resin by a conventional polycondensation reaction and then microparticulate the polyester resin. Methods for preparing a resin particle dispersion of a polyester resin include a method in which a polyester resin is pulverized by a mechanical method and dispersed in an aqueous medium using a surfactant, and a phase inversion emulsification method, but either method may be used.

[0067] When a resin particle dispersion is obtained by emulsion polymerization, the polymerizable monomers shown in the section on polymerizable monomers above can be used. Known polymerization initiators can be used as the polymerization initiator. Details will be described later.

[0068] When a surfactant is used in the resin particle dispersion preparation step, a known surfactant can be used, as will be described in detail later.

[0069] The toner particles may contain, as necessary, internal additives such as an ester compound B, a colorant, a release agent, and a charge control agent in addition to the binder resin and ester compound A. Such internal additives can be introduced into the toner particles, for example, by dissolving or dispersing them in advance in a monomer solution for forming the binder resin in the step of preparing the oil microparticle dispersion.

[0070] Alternatively, such an internal additive can be introduced into the toner particles by separately preparing a dispersion of internal additive fine particles consisting only of the internal additive, and aggregating the internal additive fine particles together with the resin fine particles and the colorant fine particles in the toner particle formation process. As the internal additive, the above-mentioned materials can be used.

[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, a colorant, a release agent, and a charge control agent can also be aggregated together with the fine particles of binder resin and the fine particles of ester compound A.

[0072] Specific methods for aggregating and fusing the binder resin particles, ester compound A particles, and other internal additive particles include the following: An aggregating agent is added to an aqueous medium to a concentration equal to or greater than the critical aggregating concentration, and the mixture is then heated to a temperature equal to or greater than the glass transition point of the binder resin particles and ester compound A particles, but less than the melting peak temperature of the mixture. This allows salting-out of the binder resin particles, ester compound A particles, and particles of other toner components, such as colorant particles, to proceed while simultaneously fusing them. When the particles have grown to the desired particle size, an aggregation terminator is added to stop particle growth. Furthermore, heating is continued as necessary to control the particle shape.

[0073] In the toner particle formation process, it is preferable to minimize the time allowed to stand after adding the aggregating agent and quickly heat the mixture to a temperature above the glass transition temperature of the binder resin particles and the ester compound A particles, but below the melting peak temperature of the mixture. While the reason for this is unclear, it is believed that the time allowed to stand after salting out can cause problems such as fluctuations in the particle aggregation state, resulting in unstable particle size distribution and variations in the surface properties of the fused particles. The time required for this temperature increase is typically preferably within 30 minutes, more preferably within 10 minutes. Furthermore, the temperature increase rate is preferably 1°C / min or more. While there is no particular upper limit for the temperature increase rate, it is preferably 15°C / min or less to prevent the generation of coarse particles due to rapid fusion. Furthermore, it is important to maintain the reaction temperature for a certain period of time after the reaction system reaches a temperature above the glass transition temperature to continue fusion. This effectively promotes the growth and fusion of core particles, thereby improving the durability of the final toner particles.

[0074] As the flocculant, known metal salts having divalent or higher valent metal ions can be used, as will be described in detail later. When a surfactant is used in the toner particle forming step, a known surfactant can be used, as will be described in detail later.

[0075] <Polymerization initiator> When emulsion polymerization is used in the resin particle dispersion preparation step, any known polymerization initiator can be used without any particular limitation. Examples of 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, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid tert-hydroperoxide, tert-butyl performate, tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetic acid, tert-butyl permethoxyacetate, and N-(3-toluyl)perbenzoyl peroxo-tert-butyl palmitate. peroxide-based polymerization initiators typified by butyl peroxide, t-butyl peroxy 2-ethylhexanoate, 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- or diazo-based polymerization initiators typified by 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile.

[0076] <Surfactant> As the surfactant used in the toner particle forming step, known anionic surfactants, cationic surfactants and nonionic surfactants can be used.

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

[0078] Examples of cationic surfactants include quaternary ammonium salts such as dodecylammonium bromide, dodecyltrimethylammonium bromide, dodecylpyridinium chloride, dodecylpyridinium bromide, hexadecyltrimethylammonium 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 ethers, 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 the measurement methods used in this specification will be described in detail below. <How to calculate the solubility parameter (SP value)> SPw1, which is the SP value of ester compound A of the present invention, and SPw2, which is the SP value of ester compound B, were determined as follows according to the calculation method proposed by Fedors. For example, the SP value (SPw1) of ester compound A (J / cm 3 ) 1 / 2When calculating the evaporation energy (Δei) (J / mol) and molar volume (Δvi) (cm) of the atom or atomic group in the molecular structure of the ester compound, refer to the table in "Polym. Eng. Sci., 14(2), 147-154 (1974)." 3 / mol) and calculate 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 as follows according to the calculation method proposed by Fedors. First, the SP value of the repeating unit constituting the styrene-acrylic resin is determined as follows: Here, the repeating unit constituting the styrene-acrylic resin refers to a molecular structure in which the double bond of the styrene-acrylic monomer used to obtain the styrene-acrylic resin by polymerization is cleaved by polymerization. For example, the SP value of the repeating unit (σ m )(J / cm 3 ) 1 / 2 When calculating the evaporation energy (Δei) (J / mol) and molar volume (Δvi) (cm) for the atom or atomic group in the molecular structure of the repeating unit, refer to the table in "Polym. Eng. Sci., 14(2), 147-154 (1974)". 3 / mol) and calculate 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 calculating the evaporation energy (Δei) and molar volume (Δvi) of each repeating unit constituting the resin, calculating the product of each repeating unit and the molar ratio (j) of each repeating unit in the resin, and then dividing the sum of the evaporation energies of each repeating unit by the sum of the molar volumes, using the following formula (10): Equation (10): σ p={(Σj×ΣΔei) / (Σj×ΣΔvi)} 1 / 2 For example, assuming that a resin is composed of two types of repeating units, X and Y, the composition ratio of each repeating unit is Wx and Wy (mass%), the molecular weight is Mx and My, the evaporation energy is Δei(X), Δei(Y), and the molar volume is Δvi(X), Δvi(Y), the molar ratio (j) of each repeating unit is Wx / Mx and Wy / My, respectively, and the solubility parameter value (σ p ) is expressed as the following equation (11). Equation (11): σ p =[{(Wx / Mx)×Δei(X)+Wy / My×Δei(Y)} / {(Wx / Mx)×Δvi(X)+Wy / My×Δvi(Y)}] 1 / 2 Furthermore, when two or more types of resin are mixed, the SP value of the mixture (σ M ) is calculated as the product of the mass composition ratio of the mixture (Wi) and the SP value (σi) of each resin, as shown in the following formula (12). Equation (12): σ M =Σ(Wi×σi)

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

[0084] <Molecular weight measurement of ester compounds by mass spectrometry> Separation of ester compounds from toner The molecular weight of the ester compound in the toner can be determined by measuring the toner, but it is more preferable to measure it after carrying out a separation operation. The toner is dispersed in ethanol, a poor solvent for the toner, and the temperature is raised to a temperature above the melting point of the ester compound. Pressure may be applied at this time if necessary. By this operation, the ester compound exceeds its melting point and is melted and extracted into the ethanol. If pressure is applied in addition to heating, the ester compound can be separated from the toner by performing solid-liquid separation while still under pressure. The extract is then dried and solidified to obtain the ester compound. The resulting ester compound can be identified and its molecular weight measured by pyrolysis GCMS using, for example, the following apparatus and measurement conditions. Mass spectrometer: ISQ manufactured by ThermoFisher Scientific GC equipment: ThermoFisher Scientific FocusGC Ion source temperature: 250℃ Ionization method: EI Mass range: 50-1000m / z Column: HP-5MS [30 m] Pyrolysis equipment: Japan Analytical Industry Co., Ltd. JPS-700 A small amount of the ester compound separated by extraction and 1 μL of tetramethylammonium hydroxide (TMAH) are added to a pyrofoil at 590°C. The resulting sample is subjected to pyrolysis GCMS measurement under the above conditions, yielding peaks for the alcohol and carboxylic acid components derived from the ester compound. The alcohol and carboxylic acid components are detected as methylated products due to the action of the methylating agent TMAH. The molecular weight of the ester compound can be determined by analyzing the peaks obtained and identifying its structure.

[0085] When the ester compound is identified and its molecular weight is measured by the direct introduction method, the following apparatus and measurement conditions can be used. Mass spectrometer: ISQ manufactured by ThermoFisher Scientific Ion source temperature: 250°C Electron energy: 70 eV Mass range: 50-1000 m / z (CI) Reagent Gas: Methane (Cl) Ionization method: ThermoFisher Scientific Direct Exposure Probe (DEP), 0mA (10sec) - 10mA / sec - 1000mA (10sec) The ester compounds separated by extraction are placed directly on the filament of the DEP unit and measured. The molecular ions in the mass spectrum of the main component peak between 0.5 and 1 minute of the resulting chromatogram are confirmed to identify the ester compounds and determine their molecular weights.

[0086] <Method for measuring the content of ester compounds in toner> The content of the ester compound in the toner can be measured using a thermal analyzer (trade name: DSC Q2000, manufactured by TA Instruments Japan, Inc.). Approximately 5.0 mg of toner sample was placed in a sample container in an aluminum pan (KIT No. 0219-0041), the sample container was placed on a holder unit, and set in an electric furnace. Under a nitrogen atmosphere, the sample was heated from 30°C to 200°C at a temperature increase rate of 10°C / min, and a differential scanning calorimeter (DSC) was used to measure the DSC curve, and the endothermic heat of the ester compound in the toner sample was calculated. The endothermic heat of the ester compound in the toner sample was also calculated in a similar manner using approximately 5.0 mg of a sample of the ester compound alone. The endothermic heat of the ester compound obtained in each measurement was then used to calculate the wax content using the following formula: Content of ester compound in toner (mass%) = (endothermic heat amount of ester compound in toner sample (J / g)) / (endothermic heat amount of ester compound alone (J / g)) × 100

[0087] <Binder resin composition analysis> -Method for separating binder resin from toner 100 mg of toner is dissolved in 3 mL of chloroform, and then the solution is suction filtered using a syringe equipped with a sample processing filter (pore size 0.2 μm to 0.5 μm, for example, Myshoridisc H-25-2 (manufactured by Tosoh Corporation)) to remove insoluble matter. The chloroform-soluble fraction obtained above is introduced into a preparative HPLC (apparatus: LC-9130 NEXT manufactured by Japan Analytical Industry Co., Ltd., preparative columns (60 cm) exclusion limits: 20,000 and 70,000, two columns connected), and chloroform is used as the eluent. When a peak is confirmed in the resulting chromatographic display, the fraction with a retention time of 2,000 or more molecular weight in a monodisperse polystyrene standard sample is collected. The solution of the obtained fraction is dried and solidified to obtain the binder resin.

[0088] Measurement of composition and weight ratios by nuclear magnetic resonance spectroscopy (NMR) 1 mL of deuterated chloroform is added to 20 mg of toner, and the NMR spectrum of the protons in the dissolved binder resin is measured. The molar and weight ratios of each monomer are calculated from the obtained NMR spectrum, and the content of styrene-derived units 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 at around 6.5 ppm derived from styrene monomer and the peak at around 3.5-4.0 ppm derived from acrylic monomer. The following equipment and measurement conditions can be used for nuclear magnetic resonance spectroscopy (NMR). NMR device: JEOL RESONANCE ECX500 Observed nucleus: proton Measurement mode: Single pulse

[0089] <Method for measuring the glass transition temperature (Tg) of styrene-acrylic resin> The glass transition temperature (Tg) of the binder resin is measured in accordance with ASTM D3418-82 using a differential scanning calorimeter (product name: Q1000, manufactured by TA Instruments). The melting points of indium and zinc are used for temperature correction of the detector, and the heat of fusion of indium is used for heat correction. Specifically, 5 mg of styrene-acrylic resin is precisely weighed and placed in an aluminum pan. Using an empty aluminum pan as a reference, measurements are performed at a heating rate of 1°C / min within a measurement range of 30 to 200°C. During this heating process, the specific heat change is measured in the temperature range of 40 to 100°C. The intersection of the line midway between the baselines before and after the specific heat change and the differential thermal curve is taken 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 the toner and toner particles is measured and analyzed under the following conditions using a flow particle image analyzer (product name: FPIA-3000, manufactured by Sysmex Corporation). The specific measurement method is as follows. First, 20 ml of ion-exchanged water, from which impurities such as solids have been removed, is placed in a glass container. 0.2 ml of a dilution of a dispersant (product name: Contaminon N, manufactured by Wako Pure Chemical Industries, Ltd.; a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder) diluted 3 times by weight with ion-exchanged water is added. 0.02 g of the measurement sample is then added, and the mixture is dispersed for 2 minutes using an ultrasonic disperser to obtain a dispersion for measurement. The dispersion is then appropriately cooled so that its temperature is between 10°C and 40°C. A tabletop ultrasonic cleaner disperser with an oscillation frequency of 50 kHz and an electrical output of 150 W (e.g., "VS-150" (manufactured by Vervoclear)) is used as the ultrasonic disperser. A predetermined amount of ion-exchanged water is placed in the water tank, and approximately 2 ml of the Contaminon N is added to the water tank.

[0091] For the measurements, a flow particle image analyzer equipped with an "UPlanApro" objective lens (10x magnification, 0.40 numerical aperture) was used, and Particle Sheath (product name: PSE-900A, manufactured by Sysmex Corporation) was used as the sheath liquid. The dispersion prepared according to the above procedure was introduced into the flow particle image analyzer, and 3,000 toner particles were measured in HPF measurement mode and total count mode. The binarization threshold for particle analysis was set to 85%, and the analyzed particle diameters were limited to those with 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, automatic focusing is performed using standard latex particles (for example, "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A" manufactured by Duke Scientific, diluted with ion-exchanged water).

[0093] <Method for measuring weight average particle size (D4)> The weight average particle diameter (D4) of the toner particles is calculated as follows. The measurement device used is a precision particle size distribution measurement device using a capillary electrical resistance method equipped with a 100 μm aperture tube (trade name: Coulter Counter Multisizer 3 (registered trademark), manufactured by Beckman Coulter, Inc.). Measurement conditions were set and measurement data was analyzed using the accompanying dedicated software (product name: Beckman Coulter Multisizer 3 Version 3.51, manufactured by Beckman Coulter, Inc.) Measurements were performed using an effective number of 25,000 measurement channels. The aqueous electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of 1.0%, for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.).

[0094] Before performing measurements and analysis, the dedicated software is set up as follows. On the "Change Standard Measurement Method (SOMME)" screen of the dedicated software, 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 Particles 10.0 μm" (Beckman Coulter, Inc.). Press the "Threshold / Noise Level Measurement 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." On the "Pulse to particle size conversion setting" screen of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin 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) Pour 200.0 mL of electrolyte solution into a 250 mL round-bottom glass beaker made specifically for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "Aperture Tube Flush" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube.

[0096] (2) 30.0 mL of the electrolyte solution is placed in a 100 mL flat-bottom glass beaker. 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 ion-exchanged water is added as a dispersant.

[0097] (3) Prepare an ultrasonic disperser "Ultrasonic Dispersion System Tetra150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two built-in oscillators with an oscillation frequency of 50 kHz and a phase shift of 180 degrees. Place 3.3 L of ion-exchanged water in the ultrasonic disperser's water tank and add 2.0 mL of Contaminon N to this water tank.

[0098] (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized.

[0099] (5) While the electrolyte solution in the beaker in (4) is being irradiated with ultrasonic waves, 10 mg of toner particles are added little by little to the electrolyte solution and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. During the ultrasonic dispersion process, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C.

[0100] (6) Using a pipette, the electrolytic solution (5) containing dispersed toner particles is dropped into the round-bottom beaker (1) placed in the sample stand, and the measurement concentration is adjusted to 5%. Then, measurements are continued until the number of particles measured reaches 50,000.

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

[0102] In the following examples, the parts are based on parts by weight. <Example of resin particle dispersion preparation process> <Preparation of Resin Particle 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. An aqueous solution of 1.5 parts of Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) dissolved in 150 parts of ion-exchanged water was added to this solution and dispersed. An aqueous solution of 0.3 parts of potassium persulfate dissolved in 10 parts of ion-exchanged water was added while slowly stirring for another 10 minutes. After the system was purged with nitrogen, emulsion polymerization was carried out at 70°C for 6 hours. After polymerization was completed, the reaction solution was cooled to room temperature, and ion-exchanged water was added to obtain resin particle dispersion 1 with a solids concentration of 20.0 mass% and a volume-based median diameter of 0.2 μm. The SP value, SPb, of the resulting styrene-acrylic resin was 20.00 (J / cm 3 ) 1 / 2 The glass transition temperature Tg was 56°C.

[0103] <Preparation of Resin Particle Dispersions 2 to 11> Resin particle dispersions 2 to 11 were obtained in the same manner as in the production example of resin 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, and the numerical values ​​for these compounds represent the number of parts.

[0105] <Example of the process for preparing ester compound A dispersion> <Preparation of Ester Compound A Dispersion 1> Pentaerythritol tetrabehenate 100.0 parts · Neogen RK 15.0 parts 385.0 parts ion-exchanged water The above materials were mixed and dispersed for about 1 hour using a wet jet mill (trade name: JN100, manufactured by Joko 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 Dispersions 2 to 6> Ester Compound A Dispersions 2 to 6 were obtained in the same manner as in the production example for Ester Compound A Dispersion 1, except that the materials used were changed as shown in Table 2 below. The concentration of each dispersion was 20% by mass.

[0107] [Table 2]

[0108] <Preparation of Ester Compound B Dispersions 1 to 5> Ester Compound B Dispersions 1 to 5 were obtained in the same manner as in the production example for Ester Compound A Dispersion 1, except that the materials used were changed as shown in Table 2. The dispersion concentrations were all 20% by mass.

[0109] [Table 3]

[0110] <Example of preparation of paraffin wax dispersion> A paraffin wax dispersion was produced in the same manner as in Production Example of Ester Compound A Dispersion 1, except that pentaerythritol tetrastearate in Production Example of Ester Compound A Dispersion 1 was changed to HNP-51 (manufactured by Nippon Seiro Co., Ltd.).

[0111] <Preparation example of colorant dispersion> As a colorant, 100.0 parts of carbon black (trade name: Nipex35, manufactured by Orion Engineered Carbons) and 15 parts of Neogen RK were mixed with 885.0 parts of ion-exchanged water, and the mixture was dispersed for about 1 hour using a wet jet mill (trade name: JN100, manufactured by Joko Corporation) to obtain a colorant dispersion.

[0112] <Example of toner particle formation process> <Formation example of toner particle 1> ·Resin particle dispersion 1 100.0 parts Ester compound A dispersion 1 8.0 parts Ester compound B dispersion 1 12.0 parts Colorant dispersion 8.0 parts The above materials were stirred using a homogenizer (trade name: Ultra Turrax T50, manufactured by IKA), while the temperature inside the container was adjusted to 30°C. A 1 mol / L aqueous solution of sodium hydroxide was added to adjust the pH of the dispersion to 8.0. An aqueous solution of 0.3 parts magnesium sulfate dissolved in 10 parts ion-exchanged water was added to the dispersion over 10 minutes while stirring at 30°C. After leaving the mixture for 3 minutes, the temperature was raised to 60°C to form aggregated particles. The particle size of the aggregated particles was measured using a Coulter Counter Multisizer 3 (manufactured by Beckman Coulter). When the weight-average particle size (D4) of the aggregated particles reached 6.5 μm, 0.9 parts sodium chloride and 5.0 parts Neogen RK were added to stop particle growth, yielding Toner Particle Dispersion 1.

[0113] Hydrochloric acid was added to the resulting toner particle dispersion 1 to adjust the pH of the dispersion to 1.5 or less. The dispersion was stirred for 1 hour, then subjected to solid-liquid separation using a pressure filter to obtain a toner cake. This was reslurried with ion-exchanged water to create a new dispersion, which was then subjected to solid-liquid separation using a pressure filter. This reslurrying and solid-liquid separation were repeated until the electrical conductivity of the filtrate reached 5.0 μS / cm or less, and finally solid-liquid separation was performed to obtain a toner cake. The resulting toner cake was dried using a flash jet dryer (manufactured by Seishin Enterprises). The drying conditions were an inlet temperature of 90°C, an outlet temperature of 40°C, and the toner cake feed rate was adjusted depending on the moisture content of the toner cake so that the outlet temperature did not deviate from 40°C. Furthermore, fine and coarse particles were removed using a multi-division classifier utilizing the Coanda effect to obtain toner particles 1. The weight average particle diameter (D4) and average circularity of toner particles 1 were measured by the above-mentioned methods, and the weight average particle diameter (D4) was 6.5 μm and the average circularity was 0.965.

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

[0115] [Table 4]

[0116] <Formation Example of Toner Particles 19> Toner particles 19 were prepared using a pulverization method as follows. Binder resin: Styrene / n-butyl acrylate / lauryl acrylate copolymer (mass ratio of styrene: n-butyl acrylate: lauryl acrylate: 81:13:6, Tg = 56 ° C.): 100.0 parts Carbon black (trade name: Nipex 35, manufactured by Orion Engineered Carbons): 8.0 parts Ester compound A (dipentaerythritol hexabehenate, melting point 87°C): 8.0 parts Ester compound B (ethylene glycol distearate): 12.0 parts The above materials were premixed in an FM mixer (manufactured by Nippon Coke and Engineering Co., Ltd.), then melted and kneaded using a twin-screw kneader (trade name: PCM-30, manufactured by Ikegai Iron Works Co., Ltd.) to obtain a kneaded mixture. The resulting kneaded mixture was cooled, coarsely pulverized using a hammer mill (manufactured by Hosokawa Micron Corporation), and then pulverized using a mechanical pulverizer (trade name: T-250, manufactured by Turbo Kogyo Co., Ltd.) to obtain a finely pulverized powder. The resulting finely pulverized powder was classified using a multi-division classifier (trade name: EJ-L-3, manufactured by Nittetsu Mining Co., Ltd.) utilizing the Coanda effect to obtain toner particles 19. The weight average particle size (D4) of toner particles 19 was 6.5 μm. The average circularity of the toner particles 19 was measured by the above method and found to be 0.940.

[0117] <Formation Example of Toner Particles 28> Toner particles 28 were formed with reference to the examples of Patent Document 1. Details are given below. (1) Preparation of dispersion of core resin particles (First stage polymerization) A reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen inlet was charged with 4 parts of sodium polyoxyethylene (2) dodecyl ether sulfate and 3,000 parts of ion-exchanged water, and the internal temperature was raised to 80°C while stirring at a stirring speed of 230 rpm under a nitrogen stream. After the temperature was raised, a solution of 10 parts of potassium persulfate in 200 parts of ion-exchanged water was added, the liquid temperature was brought 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. The mixture was then heated and stirred at 75°C for 2 hours to polymerize, preparing a dispersion of resin microparticles b1.

[0118] (Second stage polymerization) A solution of 2 parts of sodium polyoxyethylene (2) dodecyl ether sulfate dissolved in 3,000 parts of ion-exchanged water was placed in a reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device, and 42 parts (solids content equivalent) of a dispersion of resin microparticles b1 heated to 80°C, 70 parts of pentaerythritol tetrabehenate, and 70 parts of ethylene glycol distearate dissolved in a monomer solution consisting of 195 parts of styrene, 91 parts of n-butyl acrylate, 20 parts of methacrylic acid, and 3 parts of n-octyl mercaptan at 80°C was added. The mixture was mixed and dispersed for 1 hour using a mechanical disperser (product name: CLEARMIX, manufactured by M Technique Co., Ltd.) to prepare a dispersion containing emulsified particles (oil droplets). Next, an initiator solution prepared by dissolving 5 parts of potassium persulfate in 100 parts of ion-exchanged water was added to this dispersion, and the system was heated and stirred at 80°C for 1 hour to polymerize, thereby preparing a dispersion of resin microparticles b2.

[0119] (Third stage polymerization) A solution of 10 parts potassium persulfate dissolved in 200 parts ion-exchanged water was further added to the dispersion of resin microparticles b2, 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 at a temperature of 80° C. After the addition was completed, polymerization was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28° C. to obtain a dispersion of core resin microparticles C1.

[0120] (2) Preparation of dispersion of shell resin particles A surfactant solution prepared by dissolving 2.0 parts of sodium polyoxyethylene dodecyl ether sulfate in 3,000 parts of ion-exchanged water was placed in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, and the internal temperature was raised to 80°C while stirring at a stirring speed of 230 rpm under a nitrogen stream. To this solution was added an initiator solution prepared by dissolving 10 parts of potassium persulfate in 200 parts of ion-exchanged water, and a polymerizable monomer mixture containing 564 parts of styrene, 140 parts of n-butyl acrylate, 96 parts of methacrylic acid, and 12 parts of n-octyl mercaptan was added dropwise over 3 hours. After the dropwise addition, the system was heated and stirred at 80°C for 1 hour to polymerize, thereby obtaining a dispersion of shell resin particles S1.

[0121] (3) Preparation of colorant particle dispersion 90 parts of sodium dodecyl sulfate was dissolved in 1600 parts of ion-exchanged water with stirring. While stirring this solution, 420 parts of carbon black (Regal 330R, manufactured by Cabot Corporation) was gradually added, and then the mixture was dispersed using a stirring device (Clearmix, manufactured by M Technique Co., Ltd.) to prepare a dispersion Bk of colorant fine particles. The particle size of the colorant particles in the dispersion Bk of colorant particles 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) Toner particle formation (Agglomeration / fusion process) A 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen inlet was charged with 360 parts (solids equivalent) of a dispersion of core resin particles C1, 1,100 parts of ion-exchanged water, and 200 parts of a dispersion of colorant particles Bk. The liquid temperature was adjusted to 30°C, and then a 5 N aqueous solution of sodium hydroxide was added to adjust the pH to 10. Next, an aqueous solution of 60 parts of magnesium chloride dissolved in 60 parts of ion-exchanged water was added at 30°C over 10 minutes with stirring. After holding the temperature for 3 minutes, the temperature was raised 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, Inc.), and when the volume-based median diameter reached 6 μm, an aqueous solution of 40 parts of sodium chloride dissolved in 160 parts of ion-exchanged water was added to stop particle growth.Furthermore, as a maturation step, the solution was heated and stirred at a temperature of 80°C for 1 hour to promote fusion between the particles, thereby forming core particles 1.

[0123] (Shelling process) Next, 40 parts (solid content equivalent) of a dispersion of shell resin particles S1 was added, and stirring was continued for 1 hour at 80°C, causing the shell resin particles S1 to fuse to the surfaces of the core particles 1, forming a shell layer. Then, an aqueous solution of 150 parts of sodium chloride dissolved in 600 parts of ion-exchanged water was added, and aging treatment was carried out at 80°C. The average circularity of the toner particles was measured during the aging treatment, and when the desired average circularity was achieved, the mixture was cooled to 30°C.

[0124] (Washing and drying process) The produced particles were subjected to solid-liquid separation using a basket centrifuge (product name: MARKIII, model number 60x40, manufactured by Matsumoto Kikai Co., Ltd.) to form a wet cake of toner particles. This wet cake was washed with ion-exchanged water at 40°C until the electrical conductivity of the filtrate from the basket centrifuge reached 5 μS / cm, and then dried using a "Flash Jet Dryer" (manufactured by Seishin Enterprise Co., Ltd.) until the moisture content reached 0.5% by mass, thereby obtaining toner particles 28. The weight average particle diameter (D4) and average circularity of the toner particles 28 were measured by the above-mentioned methods, and the weight average particle diameter (D4) was 6.5 μm and the average circularity was 0.965.

[0125] <Formation Example of Toner Particles 29> Toner particles 29 were formed with reference to the examples in Patent Document 2. Details are given below.

[0126] (1) Manufacturing of binder resin for toner To 200 parts of ion-exchanged water, 0.2 parts of polyvinyl alcohol (PVA235, manufactured by Kuraray) as a dispersant was added. 100 parts of a monomer component 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, and 3 parts of benzoyl peroxide as a polymerization initiator, were added to prepare a dispersion. Fischer-Tropsch wax was added to this dispersion at a ratio of 9.9 parts per 100 parts of a vinyl copolymer copolymerized with the monomer components. The mixture was subjected to suspension polymerization at 125°C for 4 hours and then cooled. Prior to cooling, 25% aqueous sodium hydroxide was added to the dispersion at a volume of 2% to adjust the pH to 5.5 or higher, neutralizing the residual benzoic acid from the polymerization initiator. The resin particles were then filtered off to obtain a toner binder resin.

[0127] (2) Toner particle production 95 parts of the obtained toner binder resin, 5 parts of a colorant (trade name: Carbon Black MA-100, manufactured by Mitsubishi Chemical), and 1 part of a charge control agent (trade name: Bontron S-34, manufactured by Orient Chemical) were mixed in a small grinder and kneaded for 10 minutes at 90°C using a Labo Plastomill (manufactured by Toyo Seiki Seisakusho, capacity 100 ml, rotation speed 70 rpm). The kneaded mixture was then cooled to room temperature, pulverized using a Labo Jet Mill (manufactured by Nippon Pneumatic), and classified using an air classifier (manufactured by Nippon Pneumatic) to obtain a toner having a weight average particle size (D4) of 8.0 μm. The average circularity of the toner particles 29 was measured by the above method and was found to be 0.940.

[0128] <Toner manufacturing example> <Production of Toner 1> 100 parts of toner particles Hydrophobic silica 1.5 parts Hydrotalcite (trade name: DHT-4A, manufactured by Kyowa Chemical Industry Co., Ltd.) 0.3 parts The above materials were mixed and stirred at 3,000 rpm for 10 minutes using an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd.). The mixture was then passed through a 200-mesh sieve to obtain Toner 1. The resulting toner was analyzed according to the following methods: <Method for separating binder resin and ester compound from toner>, <Measurement of molecular weight 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>. The results showed that the ratios of the unit represented by formula (1), ester compound A, and ester compound B present in the toner were the same as those used. The physical properties of Toner 1 are shown in Table 5.

[0129] <Production of Toners 2 to 18 and Toners 21 to 24> Toners 2 to 18 and toners 21 to 24 were obtained in the same manner as in the production example of toner 1, except that toner particle 1 in the production example of toner 1 was changed to toner particles 2 to 18 and toner particles 20 to 23. The obtained toners were analyzed according to <Method for separating binder resin and ester compound from toner>, <Measurement of molecular weight of ester compound by mass spectrometry>, <Method for measuring content of ester compound in toner>, <Compositional analysis of binder resin>, and <Method for measuring average circularity of toner and toner particles>. As a result, the ratios of the unit represented by formula (1), ester compound A, and ester compound B present in the toner were the same as the ratios added. Table 5 shows the physical properties of toners 2 to 18 and toners 21 to 24.

[0130] <Production of Toner 19> 100 parts of toner particles Hydrophobic silica 1.5 parts The above materials were mixed and stirred at 3,000 rpm for 10 minutes using an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd.). The mixture was then passed through a 200-mesh sieve to obtain toner 19. The resulting toner was analyzed according to the following methods: <Method for separating binder resin and ester compound from toner>, <Measurement of molecular weight 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>. The results showed that the ratios of the unit represented by formula (1), ester compound A, and ester compound B present in the toner were the same as those used. The physical properties of Toner 19 are shown in Table 5.

[0131] <Production of Toner 20 and Toners 25-30> Toners 20 and 25-30 were obtained in the same manner as in the production example of toner 19, except that toner particle 2 in the production example of toner 19 was replaced with toner particle 19 and toner particles 24-29. The obtained toners were analyzed according to <Method for separating binder resin and ester compound from toner>, <Measurement of molecular weight 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 average circularity of toner and toner particles>. As a result, the ratios of the unit represented by formula (1), ester compound A, and ester compound B present in the toner were the same as the ratios added. Table 5 shows the physical properties of Toner 20 and Toners 25 to 30.

[0132] [Table 5]

[0133] In Table 5, in the binder resin section, "Y" indicates that the binder resin contains a unit represented by formula (1), and "N" indicates that the binder resin does not contain a unit represented by formula (1). In addition, in the ester compound A and ester compound B sections, "formula (2)" to "formula (6)" indicate compounds represented by formulas (2) to (6), respectively, and "Y" indicates that the compounds represented by formulas (2) to (6) are contained, and "N" indicates that the compounds represented by formulas (2) to (6) are not contained. "Ratio of formula (1)" indicates the ratio of the mass of the unit represented by formula (1) to the mass of the binder resin. In the hydrotalcite section, "Y" indicates that the toner contains hydrotalcite as an external additive, and "N" indicates that the toner does not contain hydrotalcite.

[0134] [Examples and Comparative Examples] Toners 1 to 30 were used and evaluated in the combinations shown in Table 6. The evaluation results are shown in Table 6. The evaluation method and evaluation criteria of the present invention will be described below. The image forming apparatus used was a commercially available laser printer, LBP-712Ci (manufactured by Canon), modified to have a process speed of 300 mm / sec and variable temperature control of the fixing unit, and a commercially available process cartridge, the toner cartridge 040H (black) (manufactured by Canon). The product toner was removed from the cartridge, cleaned with an air blower, and then filled with 165 g of the toner of the present invention. The evaluation was performed by removing the product toner from each of the yellow, magenta, and cyan stations, and inserting yellow, magenta, and cyan cartridges with the remaining toner amount detection mechanism disabled. The image gloss was evaluated in a normal temperature and humidity environment (temperature 25.0° C., relative humidity 50%). The temperature of the fixing unit was adjusted in 5°C increments within the range of 160°C to 280°C, and the media was glossy Brochure Paper 150g Glossy (Hewlett-Packard: 150g / m 2 ) and printed 50 sheets of solid black images with a printing ratio of 100%.

[0135] Image gloss was measured at five points on the first image: the upper left, upper right, center, lower left, and lower right. The average image gloss value at the five points when it was highest within the temperature range was taken as the image gloss. The temperature control temperature at which the average image gloss value at the five points was highest was taken as the fixing temperature. The standard deviation of the image gloss at the five points was taken as an index of image gloss uniformity. The evaluation criteria are as follows:

[0136] <Evaluation of image gloss> A: Image gloss is 70 or more B: Image gloss is between 60 and 70 C: Image gloss is 50 or more and less than 60 D: Image gloss is less than 50

[0137] <Evaluation of low-temperature fixability> A: Fixing temperature is 190°C or less B: Fixing temperature is over 190°C and is 200°C or less C: Fixing temperature is over 200°C and is 210°C or less D: Fixing temperature exceeds 210°C

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

[0139] Furthermore, at the fixing temperature, the adhesion of the images to the previous images was checked for the first 50 sheets, and this was used as an index of image loading ability. The evaluation criteria are as follows:

[0140] <Evaluation of image loading> A: The image is not attached B: Slight sticking is observed between the 1st and 10th sheets. C: Slight sticking is observed between the 10th and 20th sheets. D: Slight sticking is observed after the 20th sheet.

[0141] Furthermore, the offset state of the trailing edge of the image to the non-image area was checked for images up to a temperature 10° C. higher than the fixing temperature, and this was used as an index of releasability. The evaluation criteria are shown below.

[0142] <Evaluation of releasability> A: Offset is not visible B: Slight offset is observed in images with a fixing temperature 10°C higher than the fixing temperature. C: Slight offset is observed in images with a fixing temperature 5°C higher than the fixing temperature. D: Slight offset is observed in the image of the fixing temperature

[0143] Furthermore, the images for which the image gloss was confirmed were stored in a low-temperature, low-humidity environment (15°C / 10%RH) for 30 days, and the images after storage were observed with an optical microscope and visually to provide an index of image preservation. The evaluation criteria are as follows:

[0144] <Evaluation of image preservation> A: No change in the image is observed B: Minor cracks are visible under an optical microscope, but 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 toner particles containing a binder resin, an ester compound A, and an ester compound B, 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 ester compound B is an ester compound represented by the following formula (4), the following formula (5), or the following formula (6): The SP value of the styrene-acrylic resin, SPb (J / cm ３ ) １／２ and the SP value of the ester compound A, SPw1 (J / cm ３ ) １／２ the absolute value of the difference between The absolute value of the difference between the SPb (J / cm 3 ) 1 / 2 and the SP value of the ester compound B, SPw2 (J / cm 3 ) 1 / 2 , is 2.10 or less. A toner characterized by: 【Chemical 1】 (In formula (1), R １ represents a hydrogen atom or a methyl group, and R ２ represents a linear alkyl group having 10 to 14 carbon atoms. 【Chemistry 2】 【Chemistry 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. 【Chemistry 4】 【Chemistry 5】 【Chemistry 6】 (In formulas (4), (5), and (6), R 31 and R 41 each independently represent an alkylene group having 2 to 8 carbon atoms, and R 32 , R 33 , R 42 , R 43 , R 51 , and R 52 each independently represent a linear alkyl group having 14 to 24 carbon atoms.)

2. 2. The toner according to claim 1, wherein the styrene-acrylic resin contains the unit represented by formula (1) in an amount of 1% by mass to 15% by mass.

3. 3. The toner according to claim 1, wherein the ester compound A is an ester compound represented by the following formula (2') or (3'): 【Chemistry 7】 【Chemistry 8】 (In formula (2') and formula (3'), R １１ ~R １４ and R ２１ ~R ２６ each independently represents a linear alkyl group having 17 to 21 carbon atoms.

4. 4. The toner according to claim 3, wherein the ester compound A is an ester compound represented by the formula (2').

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