magnetic toner

Abstract

To provide a toner that can have an excellent low-temperature fixation property and a high resistance to abrasion in a fixed image.SOLUTION: The toner is a magnetic toner having toner particles containing a binder resin and a magnetic body, the binder resin containing a styrene-acrylic resin, the styrene-acrylic resin having a monomer unit of a long-chain alkylate unit with a straight alkyl group of the carbon number CB, the magnetic body having an alkyl group of the carbon number CM in a surface of the magnetic body, the CB and CM satisfying the following formula (a) of |CM-CB|≤10. The variation coefficient of the occupation area rate of the magnetic body in the square grid is not larger than 80.0% when a cross section of the magnetic toner is divided at the square grid with a 0.8 μm-side in an observation of a cross section of the magnetic toner using a transmission electron microscope.SELECTED DRAWING: None

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates to magnetic toners for use in copiers and printers using electrophotography and electrostatography. [Background technology]

[0002] In recent years, there has been an increasing demand for energy conservation in electrophotographic image forming apparatuses, and improvements in the low-temperature fixability of toners are required to reduce the amount of heat used to fix the toner. To improve the low-temperature fixability of toners, various studies have been conducted on binder resins used in toners. Among these, styrene-acrylic resins incorporating long-chain alkyl (meth)acrylates, which are esters of (meth)acrylic acid and alcohols with linear alkyl groups, have been investigated as binder resins with excellent melting properties. Styrene-acrylic resins incorporating long-chain alkyl (meth)acrylates are characterized by high molecular chain mobility and high compatibility with plasticizers. As a prior example aiming at improving low-temperature fixing properties, Patent Document 1 proposes a toner containing a styrene-acrylic resin having a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group with 8 to 22 carbon atoms.

[0003] Styrene-acrylic resins incorporating long-chain alkyl (meth)acrylates are also being investigated for magnetic toners. Patent Document 2 proposes a toner containing a styrene-acrylic resin having a structural unit derived from a (meth)acrylic acid alkyl ester monomer in which the alkyl group has 12 or more carbon atoms, and a magnetic material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-035506 [Patent Document 2] Japanese Patent Application Publication No. 08-320596 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as a result of the inventors' investigation of Patent Document 2, it became clear that the toner described in Patent Document 2 has a low resistance to rubbing on the surface of the fixed image, and that when multiple printed materials, such as direct mail, are transported in a stacked state, the toner contaminates other printed materials, resulting in problems with abrasion resistance. The present disclosure has been made in view of the above problems, and provides a magnetic toner that can have excellent low-temperature fixability and that provides a fixed image with excellent abrasion resistance. [Means for solving the problem]

[0006] The present disclosure provides a magnetic toner having toner particles containing a binder resin and a magnetic material, the binder resin contains a styrene-acrylic resin, The styrene-acrylic resin has a monomer unit represented by the following formula (1): R in the formula (1) 1 represents a hydrogen atom or a methyl group, R in the formula (1) 2 is the number of carbon atoms, C B represents a linear alkyl group of the formula The C B is an integer between 10 and 15, The magnetic material has a carbon number C M and having an alkyl group of the formula: The C M is an integer between 4 and 20, The C B and the C M satisfies the following formula (3), |C M -C B |≦10 (3) When a cross section of the magnetic toner is observed using a transmission electron microscope and the cross section is divided into square grids with sides of 0.8 μm, the coefficient of variation of the occupied area ratio of the magnetic material in the square grid is 80.0% or less. the law of nature , the toner particles further contain an ester compound, The ester compound is at least one ester compound selected from the group consisting of an ester compound represented by the following formula (6), an ester compound represented by the following formula (7), and an ester compound represented by the following formula (8), [ka] R in the formula (6), the formula (7) and the formula (8) 31 and R 41 each independently represents an alkylene group having 2 to 8 carbon atoms, R in the formula (6), the formula (7) and the formula (8) 32 、R 33 、R 42 、R 43 、R 51 and R 52 each independently represents a linear alkyl group having 14 to 24 carbon atoms; Characterized by magnetic Regarding toner.

[0007] [ka]

[0008] In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 is the number of carbon atoms, C B represents a straight chain alkyl group of C B is an integer between 10 and 15 inclusive. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a toner that has excellent low-temperature fixing properties and provides fixed images with excellent abrasion resistance. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this disclosure, unless otherwise specified, the expressions "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. Furthermore, the term "monomer unit" refers to the reacted form of a monomer substance in a polymer, and one section of a carbon-carbon bond in the main chain of a polymer in which a vinyl monomer is polymerized is defined as one unit. A vinyl monomer can be represented by the following formula (Z): [ka] [In formula (Z), Z1 represents a hydrogen atom or an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group), and Z2 represents an arbitrary substituent.]

[0011] The present inventors speculate as follows why the abrasion resistance of the magnetic toner according to Patent Document 2 is likely to decrease. As mentioned above, toners containing a styrene-acrylic resin incorporating a long-chain alkyl (meth)acrylate as a binder resin have excellent melting properties. On the other hand, resins incorporating a long-chain alkyl (meth)acrylate have a linear alkyl group, which makes the molecular chain highly mobile and easily deforms under external forces. Therefore, when such a styrene-acrylic resin is used in a magnetic toner, it is thought that the magnetic material present on the image surface will have poor adhesion to the toner particles after fixing. The toner proposed in Patent Document 2 is a pulverized toner that uses a styrene-acrylic resin incorporating a long-chain alkyl (meth)acrylate as the binder resin and untreated iron oxide as the magnetic material, but no effort is made to improve the adhesion between the binder resin and the magnetic material. Therefore, it is presumed that when papers are stacked and transported, the image surface is rubbed, causing the magnetic material to detach from the toner, contaminating other papers.

[0012] Therefore, the present inventors have investigated a toner that has high adhesion of a magnetic material to a binder resin on the surface of a fixed image and has excellent abrasion resistance. As a result of extensive investigation, they have found that the above-mentioned effects can be obtained by designing the binder resin and magnetic material contained in the toner as follows.

[0013] That is, the present disclosure provides a magnetic toner having toner particles containing a binder resin and a magnetic material, the binder resin contains a styrene-acrylic resin, The styrene-acrylic resin has a monomer unit represented by the following formula (1): R in the formula (1) 1 represents a hydrogen atom or a methyl group, R in the formula (1) 2 is the number of carbon atoms, C B represents a linear alkyl group of the formula The C B is an integer between 10 and 15, The magnetic material has a carbon number C M and having an alkyl group of the formula: The C M is an integer between 4 and 20, The C B and the C M satisfies the following formula (3), |C M -C B |≦10 (3) When a cross section of the magnetic toner is observed using a transmission electron microscope, the coefficient of variation of the occupied area ratio of the magnetic material in a square grid having a side length of 0.8 μm is 80.0% or less. The present invention relates to a toner characterized by the above-mentioned. |C M -C B |≦10 (3) The present disclosure also provides a magnetic toner having toner particles containing a binder resin and a magnetic material, the binder resin contains a styrene-acrylic resin, The styrene-acrylic resin has a monomer unit represented by the following formula (1): R in the formula (1) 1 represents a hydrogen atom or a methyl group, R in the formula (1) 2 is the number of carbon atoms, C B represents a linear alkyl group of the formula The C B is an integer between 10 and 15, The magnetic material has a carbon number C M a surface-treated product that has been surface-treated with a compound having an alkyl group of The C M is an integer between 4 and 20, The C B and the C M satisfies the following formula (3), |C M -C B |≦10 (3) When a cross section of the magnetic toner is observed using a transmission electron microscope, the coefficient of variation of the occupied area ratio of the magnetic material in a square grid having a side length of 0.8 μm is 80.0% or less. The present invention relates to a toner characterized by the above-mentioned.

[0014] [ka]

[0015] In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 is the number of carbon atoms, C B represents a straight chain alkyl group of C B is an integer between 10 and 15 inclusive.

[0016] <Mechanism by which the effect is manifested> The present inventors speculate as follows about the mechanism by which this effect is exerted. The monomer unit represented by formula (1) (hereinafter also referred to as the long-chain acrylate unit) has a linear alkyl group, which gives the resin a high degree of molecular chain mobility. Therefore, resins containing long-chain acrylate units have high mobility when melted and are easily made low-viscosity. Therefore, when used as a binder resin for toner, they have excellent low-temperature fixing properties. Furthermore, the binder resin and magnetic material of the toner of the present disclosure have alkyl groups with a specific number of carbon atoms. The fact that the carbon numbers of these alkyl groups satisfy formula (3) indicates that the structures of the alkyl groups are similar to each other. Because the structures of the alkyl groups are similar to each other, it is thought that orientation of the alkyl groups occurs after fixing. This orientation is thought to occur particularly easily in resins having long-chain acrylate units with high molecular chain mobility, and is an effect that takes advantage of high mobility, which is disadvantageous in terms of abrasion resistance when used alone. It is presumed that the orientation improves the adhesion between the binder resin and the magnetic material and suppresses detachment of the magnetic material. Furthermore, when the toner of the present disclosure is observed in cross section using a transmission electron microscope, the coefficient of variation (CV) of the occupied area ratio of the magnetic material when the cross section of the magnetic toner is divided into square grids with sides of 0.8 μm is 80.0% or less. This indicates that the magnetic material is uniformly dispersed in the binder resin. It is believed that uniform dispersion of the magnetic material in the binder resin reduces the amount of magnetic material that does not achieve the adhesion improvement effect due to orientation, thereby improving abrasion resistance.

[0017] The toner particles contain a binder resin and a magnetic material. Each of the components will be described below. <Binder Resin> The binder resin contains a styrene-acrylic resin having a monomer unit represented by the following formula (1). [ka]

[0018] In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 is the number of carbon atoms, C B represents a straight chain alkyl group of C B is an integer between 10 and 15 inclusive.

[0019] The long-chain acrylate unit represented by formula (1) is a straight-chain alkyl group R 2 The long-chain acrylate unit has a linear alkyl group R 2 By having the linear alkyl group R 2 The linear alkyl group R 2 The high mobility of the binder resin when melted also results in high mobility and a low viscosity of the binder resin, thereby improving low-temperature fixability and abrasion resistance.

[0020] Also, C B When C is 10 or more, the effect of reducing the viscosity of the binder resin is easily obtained, and low-temperature fixability is improved. B When C is 15 or less, the alignment of the linear alkyl groups in the binder resin with the alkyl groups on the surface of the magnetic material occurs preferentially over the alignment of the linear alkyl groups with each other in the binder resin, improving the adhesion between the binder resin and the magnetic material, and improving the abrasion resistance. B is preferably 12 or more and 14 or less, and more preferably 12.

[0021] The content of the monomer unit represented by formula (1) in the styrene-acrylic resin is preferably 1.0% by mass or more and 15.0% by mass or less. When the content of the monomer unit represented by formula (1) is 1.0% by mass or more and 15.0% by mass or less, the viscosity is further reduced, thereby improving low-temperature fixability. In addition, the orientation of the linear alkyl groups in the monomer unit represented by formula (1) with each other is suppressed, and the orientation with the alkyl groups on the surface of the magnetic material is promoted, thereby improving the adhesion between the binder resin and the magnetic material and improving abrasion resistance. The content of the monomer unit represented by formula (1) in the styrene-acrylic resin is more preferably 2.0% by mass or more and 10.0% by mass or less.

[0022] The styrene-acrylic resin may have a monomer unit represented by the following formula (5) in addition to the monomer unit represented by formula (1). [ka]

[0023] In formula (5), R 61 represents a hydrogen atom or a methyl group.

[0024] The content of the monomer unit represented by formula (5) in the styrene-acrylic resin is preferably 1.0 mass% or more and 99.0 mass% or less, more preferably 50.0 mass% or more and 90.0 mass% or less, and even more preferably 65.0 mass% or more and 85.0 mass% or less.

[0025] 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, since this facilitates enhancing affinity with the magnetic material and ester compound 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.

[0026] 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.

[0027] 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.

[0028] The content of the styrene-acrylic resin in the binder resin is preferably 90.0% by mass or more. When the content of the styrene-acrylic resin is 90.0% by mass or more, the long-chain acrylate units of the styrene-acrylic resin are uniformly dispersed in the binder resin. This allows sufficient interaction between the long-chain acrylate units and the magnetic material, improving abrasion resistance. There is no particular upper limit to the content of the styrene-acrylic resin, but it is usually 100.0% by mass or less.

[0029] In addition, as the binder resin, conventionally known resins can be used simultaneously with the styrene-acrylic resin without any particular limitation, as needed. 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.

[0030] <Polymerizable monomer> The styrene-acrylic resin may be obtained by polymerization. Examples of polymerizable monomers that form the monomer unit represented by formula (1) include decyl acrylate, decyl methacrylate, lauryl acrylate, lauryl methacrylate, myristyl acrylate, myristyl methacrylate, pentadecyl acrylate, and pentadecyl methacrylate. Examples include acrylic acid esters and methacrylic acid esters having a linear alkyl group of 10 to 15. Among these, it is preferable to use lauryl acrylate, lauryl methacrylate, myristyl acrylate or myristyl methacrylate, and it is more preferable to use lauryl acrylate or lauryl methacrylate.

[0031] Examples of polymerizable monomers that form the monomer unit represented by formula (5) include styrene and α-methylstyrene, and among these, it is preferable to use styrene.

[0032] The styrene-acrylic resin may contain, in addition to the monomer unit represented by formula (1), monomer units of other known polymerizable monomers without any particular limitation. Other polymerizable monomers include monofunctional monomers having one polymerizable unsaturated bond in the molecule, such as acrylic acid esters such as methyl acrylate and n-butyl acrylate (n-butyl acrylate); methacrylic acid esters such as methyl methacrylate, 2-hydroxyethyl methacrylate, t-butyl methacrylate, and 2-ethylhexyl methacrylate; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; unsaturated dicarboxylic acids such as maleic acid; unsaturated dicarboxylic acid anhydrides such as maleic anhydride; nitrile-based vinyl monomers such as acrylonitrile; halogen-containing vinyl monomers such as vinyl chloride; and nitro-based vinyl monomers such as nitrostyrene; and 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.

[0033] Among these, it is preferable to use an acrylic acid ester or a methacrylic acid ester (preferably having an alkyl group with 1 to 8 carbon atoms (more preferably 1 to 4 carbon atoms)), and it is even more preferable to use n-butyl acrylate. The content of monomer units of (meth)acrylic acid esters having an alkyl group with 1 to 8 carbon atoms (more preferably 1 to 4 carbon atoms) in the styrene-acrylic resin is preferably 0.0% by mass to 45.0% by mass, more preferably 5.0% by mass to 35.0% by mass. The content of monomer units of n-butyl acrylate in Resin A is preferably 0.0% by mass to 25.0% by mass.

[0034] <Magnetic material> Examples of magnetic materials include iron oxides such as magnetite, maghemite, and ferrite; metals such as iron, cobalt, and nickel; alloys of these metals with metals such as aluminum, cobalt, copper, magnesium, zinc, antimony, beryllium, bismuth, calcium, manganese, selenium, titanium, tungsten, and vanadium; and mixtures thereof. Among these, magnetite is preferred.

[0035] The magnetic material has a carbon number C M and has an alkyl group of C M is an integer between 4 and 20 inclusive.

[0036] C M When C is 4 or more, the alkyl groups on the surface of the magnetic material are easily oriented with the long-chain acrylate units of the styrene-acrylic resin. This improves the adhesion between the binder resin and the magnetic material, improving the abrasion resistance. M is preferably 6 or more, more preferably 8 or more. M When C is 20 or less, coalescence of the magnetic particles is suppressed, and dispersion of the magnetic particles in the binder resin is improved. M is preferably 16 or less, and more preferably 14 or less. Furthermore, "a magnetic body having an alkyl group on its surface" includes a mode in which a compound having an alkyl group is physically adsorbed to the surface of the magnetic body, and a mode in which a chemical reaction occurs between a compound having an alkyl group and the surface of the magnetic body to form a chemical bond.

[0037] Also, C B and C M satisfies the following formula (3). |C M -C B |≦10...Equation (3)

[0038] C B and C M satisfies formula (3), the linear alkyl group R 2Since the structure of C is similar to the structure of the alkyl groups in the magnetic material, the alignment of the alkyl groups is facilitated. This improves the adhesion between the binder resin and the magnetic material, suppresses the detachment of the magnetic material, and improves the abrasion resistance. B and C M However, it is preferable that the following formula (4) is satisfied. |C M -C B |≦8...Equation (4)

[0039] The magnetic material is preferably a surface-treated product that has been surface-treated with a compound having an alkyl group. The surface treatment agent having an alkyl group is not particularly limited, but examples thereof include a silane coupling agent, an alkyl-modified silicone, a fatty acid, and a titanium coupling agent. The surface treatment method for the magnetic material is not particularly limited as long as it is a treatment method using a compound having an alkyl group. Examples of such methods include a wet method in which a powder to be treated is dispersed in a solvent such as water or an organic solvent using a mechanochemical mill such as a ball mill or sand grinder, followed by mixing with a surface treatment agent, and then removing the solvent and drying; a dry method in which the powder to be treated and the surface treatment agent are mixed using a Henschel mixer, super mixer, Mix Marler, or the like, followed by drying; and a method in which the powder to be treated is brought into contact with the surface treatment agent in a high-speed airflow such as in a jet mill to perform the treatment. Among these, the dry method using a Mix Marler is preferred. The form of the surface-treated product is not particularly limited, but examples include a form in which a compound having an alkyl group is physically adsorbed to the surface of the magnetic material, and a form in which a chemical reaction occurs between the compound having an alkyl group and the surface of the magnetic material to form a chemical bond.

[0040] The SP value of the surface treatment agent is SPm (J / cm 3 ) 1 / 2In this case, SPm is preferably 17.00 or more and 19.00 or less, since this facilitates enhancing affinity with the styrene-acrylic resin and the ester compound described below. Furthermore, SPm is more preferably 17.40 or more and 18.20 or less. The SP value of the surface treatment agent refers to the SP value in the state after the surface treatment agent has reacted with the magnetic material surface. The method for calculating the SP value will be described later.

[0041] The absolute value of SPb-SPm is preferably 3.00 or less. When the absolute value of SPb-SPm is 3.00 or less, the alkyl group of the surface treatment agent and the linear alkyl group R 2 The absolute value of the difference between SPb and SPm is more preferably 2.10 or less.

[0042] The number average particle size of the primary particles of the magnetic material is preferably 50 nm or more and 500 nm or less, more preferably 100 nm or more and 300 nm or less, and even more preferably 150 nm or more and 250 nm or less. Furthermore, the standard deviation of the number-average particle size is preferably 50 nm or more and 90 nm or less, and more preferably 60 nm or more and 80 nm or less. Having the standard deviation of the number-average particle size of the primary particles of the magnetic material within the above range results in a good balance between magnetic material with relatively large particle size, which has good dispersibility and increases the thermal conductivity of the toner, and magnetic material with relatively small particle size, which is advantageous for low-temperature fixability, thereby improving the fixability of images with a high toner coverage, such as full-area solid images, where heat is not easily transferred to the entire toner. The standard deviation of the number-average particle size of the primary particles of the magnetic material can be freely controlled by adjusting the conditions of the oxidation reaction during magnetic material production.

[0043] The content of the magnetic material in the toner is preferably 40 parts by mass or more and 120 parts by mass or less, and more preferably 50 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the binder resin. It's nice. When the content of the magnetic material is within the above range, it becomes easier to achieve both low-temperature fixability and control of the dispersibility of the magnetic material.

[0044] <Dispersion state of magnetic material in toner> When a cross section of the magnetic toner is observed using a transmission electron microscope and the cross section is divided into square grids with sides of 0.8 μm, the coefficient of variation (CV) of the occupied area ratio of the magnetic material in the square grid is 80.0% or less. The coefficient of variation of the occupied area ratio of the magnetic material is more preferably 60.0% or less. There is no particular restriction on the lower limit of the coefficient of variation of the occupied area ratio of the magnetic material, but it is usually 0% or more. The fact that the coefficient of variation of the occupied area ratio of the magnetic material is within the above range indicates that the magnetic material is uniformly dispersed in the toner. Uniform dispersion of the magnetic material in the toner reduces the amount of magnetic material that does not achieve the adhesion improvement effect due to orientation, improving abrasion resistance.

[0045] When observing the cross section of a magnetic toner using a transmission electron microscope, the average area ratio of the magnetic particles in the square grid, when divided into sections with a side length of 0.8 μm, is preferably 10.0% or more and 50.0% or less. It is more preferably 20.0% or more and 40.0% or less. When the average area ratio is within the above range, the magnetic particles are properly dispersed in the toner, and the amount of magnetic particles that do not achieve the effect of improving adhesion due to orientation with the binder resin is reduced. This improves abrasion resistance.

[0046] The dispersion state of the magnetic material in the toner can be controlled by the combination of the resin material and magnetic material used in the toner, the toner manufacturing conditions, and the like.

[0047] <Thermal conductivity of toner> The thermal conductivity of the magnetic toner, measured by the hot disk method, is preferably 0.190 W / mK or higher, and more preferably 0.200 W / mK or higher. By keeping the thermal conductivity of the toner within this range, it becomes possible to efficiently transfer heat from the fixing device to the toner on the media in the fixing nip, improving the fixability of images with a high toner coverage, such as full-surface solid images, where heat is difficult to transfer to the entire toner. There is no particular upper limit for the thermal conductivity of the magnetic toner, but it is usually 0.300 W / mK or lower. The thermal conductivity of the magnetic toner can be controlled by adjusting the content and dispersion state of the magnetic material. Generally, the thermal conductivity tends to increase as the content of the magnetic particles increases and as the dispersibility increases.

[0048] <Ester compounds> The toner preferably contains at least one ester compound selected from the group consisting of ester compounds represented by the following formulas (6), (7), and (8). [ka]

[0049] In formula (6), formula (7) and formula (8), R 31 and R 41 each independently represents an alkylene group having 2 to 8 carbon atoms, and R 32 , R 33 , R 42 , R 43 , R 51 and R 52 are each independently a linear alkyl group having 14 or more and 24 or less carbon atoms (preferably 16 or more and 24 or less, more preferably 17 or more and 22 or less).

[0050] The above ester compounds have high compatibility with styrene-acrylic resins, and therefore, by using the above ester compounds, it is possible to obtain the effect of lowering the viscosity at lower temperatures, thereby improving the low-temperature fixability.

[0051] The SP value of the ester compound is SPw (J / cm 3 ) 1 / 2 In this case, SPw is preferably 17.50 or more and 18.50 or less, since this facilitates enhancing affinity with the styrene-acrylic resin and the magnetic material. More preferably, SPw is 17.90 or more and 18.30 or less, and even more preferably, SPw is 18.00 or more and 18.20 or less. SPw can be controlled by the number of carbon atoms in the linear alkyl group of the ester compound and the number of ester bonds.

[0052] The absolute value of SPb-SPw is preferably 2.50 or less. When the absolute value of SPb-SPw is 2.50 or less, the ester compound is easily compatible with the styrene-acrylic resin, improving low-temperature fixability. In addition, the ester compound does not bleed onto the toner surface in a high-temperature environment due to the linear alkyl group R 2 The absolute value of SPb-SPw is more preferably 2.10 or less, and even more preferably 2.00 or less.

[0053] The absolute value of SPm-SPw is preferably 1.10 or less. When the absolute value of SPm-SPw is 1.10 or less, the ester compound becomes more compatible with the alkyl group of the magnetic material, and the magnetic material surface is more likely to be coated with the ester compound. This reduces friction on the magnetic material surface, making it less likely for the magnetic material on the fixed image surface to come off when rubbed. This significantly improves abrasion resistance. The absolute value of SPm-SPw is more preferably 0.70 or less, and even more preferably 0.60 or less.

[0054] The ester compounds represented by formulas (6) to (8) have a linear structure, which allows them to exhibit sharp melting characteristics. In addition, the presence of multiple ester bonds in the molecule makes it easy to control the difference in SP value with styrene-acrylic resins, further enhancing the effect of reducing the viscosity of the toner.

[0055] Examples of the ester compound represented by formula (6) 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, and octanediol dibehenate.

[0056] Examples of the ester compound represented by formula (7) include distearyl succinate, dibehenyl succinate, distearyl adipate, dibehenyl adipate, distearyl suberate, dibehenyl suberate, distearyl sebacate, and dibehenyl sebacate.

[0057] Examples of the ester compound represented by formula (8) include palmityl palmitate, stearyl palmitate, behenyl palmitate, palmityl stearate, stearyl stearate, behenyl stearate, palmityl behenate, stearyl behenate, and behenyl behenate.

[0058] Among these, it is preferable to use the ester compound represented by formula (6) or formula (7), and it is more preferable to use ethylene glycol distearate, because it is easy to improve compatibility with the styrene-acrylic resin having the long-chain acrylate unit represented by formula (1).

[0059] The content of the ester compound 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.

[0060] The melting point of the ester compound is preferably 65°C or higher and 90°C or lower, and more preferably 70°C or higher and 85°C or lower.

[0061] <Release agent> The toner particles may contain a known wax as a release agent in addition to the above specific ester compound. As a release agent, hydrocarbon wax is preferred because it has high phase separation properties with respect to styrene-acrylic resins and therefore has a high release effect. Examples of hydrocarbon waxes include aliphatic hydrocarbon waxes such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax or block copolymers thereof; and waxes obtained by grafting aliphatic hydrocarbon waxes with vinyl monomers such as styrene and acrylic acid. The content of the release agent other than the ester compound is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the binder resin.

[0062] <Charge control agent> The toner may contain a charge control agent to stabilize the chargeability. The charge control agent is not particularly limited, but is preferably an organometallic complex or chelate compound in which the central metal easily interacts with the acid group or hydroxyl group present at the end of the binder resin. Specific examples include monoazo metal complexes; acetylacetone metal complexes; and metal complexes or metal salts of aromatic hydroxycarboxylic acids or aromatic dicarboxylic acids.

[0063] <Average circularity of toner> The average circularity of the toner is preferably 0.910 or more and 0.995 or less. When the average circularity of the toner is in the above range, the image surface after fixing tends to be smooth, and the abrasion resistance is further improved. The average circularity of the toner is more preferably 0.930 or more and 0.995 or less, and more preferably 0.940 or more and 0.995 or less. The method for measuring the average circularity of the toner will be described later.

[0064] The method for producing the toner of the present disclosure will be described in detail below. The method for producing the magnetic toner is not particularly limited, and known production methods such as pulverization, suspension polymerization, solution suspension, emulsion aggregation, dispersion polymerization, etc. Among these, pulverization is preferred because it allows for high control of the dispersibility of the magnetic material.

[0065] <Crushing method> The pulverization method will be described in detail below. (i) The binder resin and magnetic material that constitute the toner particles, as well as wax and other additives as necessary, are thoroughly mixed in a mixer such as an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) to prepare a mixture containing the binder resin and the magnetic material. (ii) The resulting mixture is melt-kneaded using a thermal kneader such as a TEX twin-screw kneader (manufactured by The Japan Steel Works, Ltd.) to make the resins compatible with each other, and the magnetic material and other additives are dispersed or dissolved therein to prepare a kneaded mixture. (iii) The resulting kneaded product is cooled and solidified, and then pulverized to prepare a pulverized product. (iv) The resulting pulverized product is subjected to classification or the like to obtain toner particles.

[0066] In order to control the shape and surface properties of the toner particles, a surface treatment step may be included in which the toner particles obtained by classification or the like are passed through a surface treatment device that continuously applies a mechanical impact force to the toner particles. By controlling the treatment time of this surface treatment step, it is also possible to control the surface shape of the toner particles.

[0067] The mixers include the following: FM Mixer (manufactured by Nippon Coke Engineering Co., Ltd.); Super Mixer (manufactured by Kawata Co., Ltd.); Ribocone (manufactured by Okawara Manufacturing Co., Ltd.); Nauta Mixer, Turbulizer, Cyclomix (manufactured by Hosokawa Micron Co., Ltd.); Spiral Pin Mixer (manufactured by Pacific Kiko Co., Ltd.); Lödige Mixer (manufactured by Chuo Kiko Co., Ltd.).

[0068] Examples of the kneading machine include the following: KRC kneader (manufactured by Kurimoto Iron Works); Buss-Co kneader (manufactured by Buss); TEM type extruder (manufactured by Shibaura Machinery); TEX twin-screw kneader (manufactured by The Japan Steel Works); PCM kneader (manufactured by Ikegai Corporation); three-roll mill, mixing roll mill, kneader (manufactured by Inoue Seisakusho); Kneadex (manufactured by Mitsui Mining Co., Ltd.); MS-type pressure kneader, Niderruder (manufactured by Moriyama Seisakusho); Banbury mixer (manufactured by Kobe Steel, Ltd.).

[0069] The crushers include the following: Counter jet mill, Micron Jet, Innomizer (manufactured by Hosokawa Micron Corporation); IDS type mill, PJM jet pulverizer (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); Cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); Urmax (manufactured by Nisso Engineering Co., Ltd.); SK Jet-O-Mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries Co., Ltd.); Turbo mill (Turbo Boe Industry Co., Ltd.); Super rotor (manufactured by Nisshin Engineering Co., Ltd.).

[0070] The classifiers include the following: Cruseal, Micron Classifier, Spedic Classifier (manufactured by Seishin Enterprises); Turbo Classifier (manufactured by Nisshin Engineering); Micron Separator, Turboplex (ATP), TSP Separator (manufactured by Hosokawa Micron); Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Industry Co., Ltd.); YM Microcut (manufactured by Yaskawa Shoji Co., Ltd.).

[0071] Examples of surface modification devices include the following: Faculty (manufactured by Hosokawa Micron Corporation), Mechanofusion (manufactured by Hosokawa Micron Corporation), Nobilta (manufactured by Hosokawa Micron Corporation), Hybridizer (manufactured by Nara Machinery Co., Ltd.), Innomizer (manufactured by Hosokawa Micron Corporation), Theta Composer (manufactured by Tokuju Kogyosho Co., Ltd.), Mechanomill (manufactured by Okada Seiko Co., Ltd.).

[0072] Examples of sieving devices used to sift out coarse particles include the following: Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonaseave, Gyroshifter (Tokuju Kogyosho Co., Ltd.); Vibrasonic system (manufactured by Dalton Co., Ltd.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); Turboscreener (manufactured by Turbo Industry Co., Ltd.); Microshifter (manufactured by Makino Sangyo Co., Ltd.); circular vibrating sieve.

[0073] <External addition process> The toner preferably contains an external additive (external additive). When the toner contains an external additive, the fluidity, chargeability, and blocking properties are improved. The external addition step is not particularly limited as long as the external additive can be attached to the surface of the toner particles. For example, the external additive and the toner particles can be placed in a mixing device such as an FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) and thoroughly mixed.

[0074] As the external additive, any known external additive can be used without any particular limitation. Examples of external additives include raw silica fine particles such as wet process silica and dry process silica, or surface-treated silica fine particles obtained by surface-treating such raw silica fine particles with a treating agent such as a silane coupling agent, a titanium coupling agent, or silicone oil; metal oxide fine particles typified by titanium oxide fine particles, aluminum oxide fine particles, zinc oxide fine particles, and tin oxide fine particles, or metal oxide fine particles obtained by hydrophobizing metal oxides; fatty acid metal salts typified by zinc stearate, calcium stearate, and zinc stearate; metal complexes of aromatic carboxylic acids typified by salicylic acid, alkyl salicylic acid, dialkyl salicylic acid, naphthoic acid, and dicarboxylic acid; clay minerals typified by hydrotalcite; fluorine-based resin fine particles typified by vinylidene fluoride fine particles and polytetrafluoroethylene fine particles; inorganic fine particles such as calcium carbonate, calcium phosphate, and cerium oxide; and organic fine particles such as polymethyl methacrylate resin, silicone resin, and melamine resin.

[0075] Among these, it is preferable to use surface-treated silica fine particles treated with silicone oil. Since silicone oil has a large friction reduction effect, being present on the surface of the external additive for toner can suppress toner fusion (hereinafter also referred to as drum fusion) to the photosensitive drum, which becomes prominent during continuous use in a high-temperature and high-humidity environment. Drum fusion mainly occurs due to the pressure at the contact portion between the photosensitive drum and the cleaning blade. Therefore, the above effect is particularly easily obtained when a resin that is easily deformed by an external force, such as the styrene-acrylic resin of the present disclosure, is used as the binder resin. In addition, the silicone oil-treated silica reduces the frictional force on the image surface by being present on the image surface after fixing, and improves the abrasion resistance.

[0076] As the silicone oil, conventionally known silicone oil can be used without particular limitation. For example, dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, etc. can be mentioned. The viscosity of the silicone oil is preferably 10 cs or more and 500 cs or less. The content of the external additive is preferably 0.1 part by mass or more and 5.0 parts by mass or less with respect to 100.0 parts by mass of the toner particles.

[0077] Hereinafter, the method for measuring each physical property value of the toner according to the present disclosure will be described. <Calculation method of SP value> Follow the calculation method proposed by Fedors. For atoms or atomic groups in the molecular structure, the evaporation energy (Δei) (cal / mol) and molar volume (Δvi) (cm 3 / mol) are obtained from the table described in "polym.Eng.Sci., 14(2), 147-154(1974)". (4.184×ΣΔei / ΣΔvi) 1 / 2 is taken as the SP value (J / cm 3 ) 1 / 2 SPb is calculated from the composition of the monomer units of the styrene-acrylic resin. SPm is calculated from the form after the surface treatment agent reacts with the magnetic body surface. SPw is calculated from the composition of the acid and alcohol of the ester compound.

[0078] <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 under reduced pressure 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 with a molecular weight of less than 2000 are separated as ester compounds, and high-molecular-weight components with a molecular weight of 2000 or more are separated as binder resins. Preparative GPC device: Preparative HPLC (product name: LC-980 model, manufactured by Nippon Analytical Industry Co., Ltd.) Preparative column: JAIGEL 3H, JAIGEL 5H (manufactured by 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.

[0079] (Separation of toner particles from toner) If necessary, the measurement can be carried out using toner particles from which external additives have been removed by the following method. Add 160 g of sucrose (Kishida Chemical) to 100 mL of ion-exchanged water and dissolve in a hot water bath to prepare a sucrose concentrate. Add 31 g of the sucrose concentrate and 6 mL of Contaminon N (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of nonionic surfactants, anionic surfactants, and organic builders, manufactured by Wako Pure Chemical Industries, Ltd.) to a centrifuge tube (50 mL). Add 1.0 g of toner and break up any clumps with a spatula. Shake the centrifuge tube at 300 strokes per minute (spm) for 20 minutes using a shaker (AS-1N, AS ONE Corporation). After shaking, transfer the solution to a 50 mL glass tube for a swing-out rotor and separate it in a centrifuge (H-9R, Kokusan Corporation) at 3500 rpm for 30 minutes. This operation separates the toner particles from the external additives. Visually confirm that the toner particles and aqueous solution have been sufficiently separated, and collect the toner particles that have separated to the top layer with a spatula or similar. The collected toner particles are filtered through a vacuum filter and then dried in a dryer for at least one hour to obtain a sample for measurement. This operation is repeated multiple times to ensure the required amount.

[0080] <Molecular weight measurement of ester compounds by mass spectrometry> Separation of ester compounds from toner The molecular weight of the ester compound can be measured in the toner as it is, but it is difficult to measure it after separation. As the separation operation, a method for separating the binder resin and the ester compound from the toner may be used, or the following method may be used. 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 has exceeded 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 ester compound can be identified and its molecular weight measured by pyrolysis GCMS using the following equipment and measurement conditions.

[0081] Identification and molecular weight measurement of ester compounds by pyrolysis-GCMS 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. Due to the action of the methylating agent TMAH, the alcohol and carboxylic acid components are detected as methylated products. The molecular weight can be determined by analyzing the peaks obtained and identifying the structure of the ester compound.

[0082] 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. Identification and molecular weight measurement of ester compounds by direct injection method 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.

[0083] <Method for measuring the glass transition temperature (Tg) of binder 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 to correct the temperature of the detector, and the heat of fusion of indium is used to correct the heat quantity. Specifically, 5 mg of binder resin is precisely weighed and placed in an aluminum pan. An empty aluminum pan is used as a reference, and measurement is performed in the measurement range of 30 to 200°C at a temperature increase rate of 1°C / min. During this temperature increase process, the specific heat change is obtained 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 appears and the differential thermal curve is taken as the glass transition temperature (Tg) of the binder resin.

[0084] <Binder resin composition analysis> - Binder resin separation method The molecular weight of the binder resin can be measured in the toner itself, but it is more preferable to measure it after a separation operation. The separation operation may be a method of separating the binder resin and the ester compound from the toner, or the following method may be used. Dissolve 100 mg of toner in 3 mL of chloroform. Next, remove the insoluble matter by suction filtration using a syringe equipped with a sample processing filter (pore size 0.2 μm to 0.5 μm, such as Myshoridisk H-25-2 (Tosoh Corporation)). The soluble matter is introduced into a preparative HPLC (apparatus: Japan Analytical Industry Co., Ltd. LC-9130 NEXT preparative column [60 cm], exclusion limits: 20,000 and 70,000, two columns connected), and chloroform eluent is pumped. Once a peak is confirmed in the resulting chromatographic display, fractionate the retention time with a molecular weight of 2,000 or higher using a monodisperse polystyrene standard sample. The resulting solution is dried and solidified to obtain the binder resin. Measurement of composition ratio and weight ratio by nuclear magnetic resonance spectroscopy (NMR), and C B Identification of 1 mL of deuterated chloroform was added to 20 mg of the binder resin obtained above, and the proton NMR spectrum of the dissolved binder resin was measured. The molar ratio and weight ratio of each monomer were calculated from the obtained NMR spectrum, and the content of units derived from styrene could 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 the styrene monomer and the peak at around 3.5-4.0 ppm derived from the acrylic monomer. Furthermore, in the case of a polyester resin, which is commonly used as a binder resin for toner, the molar ratio and weight ratio can be calculated based on the peaks derived from each monomer constituting the polyester resin and the peak derived from the styrene-acrylic copolymer, and the content of units derived from styrene can be determined. Furthermore, by identifying the monomer unit represented by formula (1) contained in the styrene-acrylic resin from the obtained NMR spectrum, C B is required. 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

[0085] <C M Identification of 100 mg of toner is mixed with 10 mL of chloroform and homogenized for 10 minutes to dissolve the binder resin. The magnetic material is then collected using a magnet. This process is repeated several times to isolate the magnetic material. The obtained magnetic material is subjected to pyrolysis GCMS under the following conditions. From the measurement results, the pyrolysis product of the compound having alkyl groups present on the surface of the magnetic material is obtained. By analyzing the peaks derived from the main components of the pyrolysis product and identifying the structure of the alkyl groups, C M The pyrolysis products are detected as alkyl-substituted compounds of compounds having alkyl groups present on the surface of the magnetic material, or their double bond-modified products, alkylsilanes, etc. Mass spectrometer: ThermoFisherScinetificsha ISQ GC equipment: ThermoFisher Scientific FocusGC Ion source temperature: 250℃ Ionization method: EI Mass range: 50-1000m / z Column: HP-5MS [30 m] Pyrolysis device: Japan Analysis Industry Co., Ltd. JPS-700

[0086] <Method for measuring average circularity of toner> 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, and 0.2 mL of a solution prepared by diluting 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, anionic surfactant, and organic builder) three times by weight with ion-exchanged water is added. 0.02 g of the sample to be measured 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 cooled appropriately so that the 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" (Velvoclear)) is used as the ultrasonic disperser. A predetermined amount of ion-exchanged water is placed in the water tank, and 2 mL of Contaminon N is added to the water tank.

[0087] For the measurement, a flow-type particle image analyzer equipped with an "UPlanApro" objective lens (magnification 10x, numerical aperture 0.40) 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-type 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 circle-equivalent diameter of 1.985 μm or more and less than 39.69 μm, and the average circularity of the toner particles was determined. 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).

[0088] <Method of calculating the occupied area ratio of magnetic material in toner and its coefficient of variation (CV)> The occupied area ratio of the magnetic material in the toner and its coefficient of variation (CV) are calculated as follows. First, a cross-sectional image of the toner is obtained using a transmission electron microscope (TEM). The obtained cross-sectional image is then subjected to a division method to obtain a frequency histogram of the occupied area ratio of the magnetic material in each division grid. Furthermore, the coefficient of variation of the occupied area ratio for each division grid is calculated and used as the coefficient of variation of the occupied area ratio. Specifically, magnetic toner was first compressed into a tablet. 100 mg of magnetic toner was loaded into an 8 mm diameter tablet former and left to stand for 1 minute under a force of 35 kN to obtain a tablet. The resulting tablet was then cut using an ultrasonic ultramicrotome (Leica, UC7) to obtain a 250 nm thick slice sample. STEM images of the resulting slice sample were taken using a transmission electron microscope (JEOL, JEM2800). The probe size used for STEM imaging was 1.0 nm, and the image size was 1024 x 1024 pixels. By adjusting the contrast on the Detector Control panel for bright-field images to 1425, brightness to 3750, and contrast to 0.0, brightness to 0.5, and gamma to 1.00 on the Image Control panel, only the magnetic material portion was captured darkly. These settings allowed for the generation of STEM images suitable for image processing. The obtained STEM images are digitized using an image processing device (Nireco Corporation, LUZEX AP). Specifically, a frequency histogram of the occupied area ratio of the magnetic material in a square grid with a side length of 0.8 μm is obtained using the division method. The histogram class interval is set to 5%. Furthermore, the coefficient of variation (CV) is calculated from the obtained occupied area ratio of each division grid and the average value of the occupied area ratios. The average occupied area ratio is also calculated by averaging the occupied area ratios of each division grid.

[0089] <Method for calculating the number average particle size and its standard deviation of magnetic particles in toner> The number average particle diameter of the magnetic particles in the toner and its standard deviation are calculated as follows. The magnetic material obtained by the above isolation method is heated in an electric furnace at 800°C for 30 minutes to decompose any remaining organic components. The remaining magnetic material is recovered and observed with a scanning electron microscope (SEM) and analyzed with an energy dispersive X-ray analyzer (EDX). Observation is performed at a magnification of 10,000x, and EDX analysis confirms that the particles are composed of iron and oxygen (including trace elements such as Si, if necessary), and the long diameter of the particles is determined using image processing software. 200 particles are measured, and the number-average particle size is calculated from the average value, and the standard deviation is also calculated. SEM: JEOL JSM7800 EDX: ThermoFisher Scientific Talos F200X Image processing software: Nireco image analyzer (Luzex AP)

[0090] <Measurement of thermal conductivity of toner> (1) Preparation of measurement samples The measurement sample is made by compressing approximately 5 g of toner (this varies depending on the specific gravity of the sample) for 60 seconds at 20 MPa using a tablet compression machine in an environment of 25°C, and creating two cylindrical pieces with a diameter of 25 mm and a height of 6 mm. (2) Measurement of thermal conductivity Measurement equipment: Hot disc method thermophysical property measurement equipment TPS2500S Sample holder: Room temperature sample holder Sensor: Standard (RTK) sensor Software:Hot disk analysis 7 Place the measurement sample on the mounting table of the room temperature sample holder and adjust the height of the table so that the surface of the measurement sample is at the same height as the sensor. Place the second measurement sample on top of the sensor, followed by the included metal piece, and apply pressure using the screw above the sensor. Adjust the pressure to 10 cN·m with a torque wrench. Make sure that the centers of the measurement sample and sensor are directly below the screw. Start Hot disk analysis and select Bulk (Type Select I). Enter the following into the input fields: Available Probing Depth: 6mm Measurement time: 40 seconds Heating Power: 60mW Sample Temperature: 23℃ TCR:0.004679K-1 Sensor Type:Disk Senor Material Type: Kapton Sensor Design: 5465 Sensor Radius: 3.189 mm After entering the above, start the measurement. After the measurement is completed, select the Calculate button, enter Start Point: 10 and End Point: 200, select the Standard Analysis button, and calculate the Thermal Conductivity [W / mK]. [Example]

[0091] The toner of the present disclosure will be described in detail below using examples and comparative examples, but the present disclosure is not limited to these examples. In the following description of the examples, "parts" are based on mass unless otherwise specified.

[0092] <Production example of binder resin A1> Styrene 81.00 parts n-Butyl acrylate 13.00 parts n-Lauryl acrylate 6.00 parts The above materials were uniformly dispersed and mixed using an attritor (Nippon Coke and Engineering Co., Ltd.). The obtained monomer composition was heated to a temperature of 60° C., and the following materials were mixed and dissolved therein to prepare a polymerizable monomer composition. Polymerization initiator 10.00 parts (t-Butyl peroxypivalate (25% toluene solution)) On the other hand, 450 parts of a 0.1 mol / L Na3PO4 aqueous solution was added to 720 parts of ion-exchanged water and heated to a temperature of 60°C, and then 67.7 parts of a 1.0 mol / L CaCl2 aqueous solution was added to obtain an aqueous medium containing a dispersion stabilizer.

[0093] The polymerizable monomer composition was added to the aqueous medium obtained above, and the mixture was mixed for 200 seconds at 60°C under a nitrogen atmosphere using a TK homomixer (Tokushu Kika Kogyo Co., Ltd.). -1 The mixture was stirred with a paddle impeller for 15 minutes at 70°C for granulation, and the polymerization reaction was carried out for 300 minutes at 70°C. Thereafter, the resulting suspension was cooled to room temperature at a rate of 3° C. per minute, hydrochloric acid was added to dissolve the dispersant, and the suspension was filtered, washed with water, and dried to obtain a binder resin A1.

[0094] <Production Examples of Binder Resins A2 to A13> Binder resins A2 to A13 were obtained in the same manner as in the production example of binder resin A1, except that the monomer formulation was changed to that shown in Table 1. [Table 1] In Table 1, St represents styrene, n-BA represents n-butyl acrylate, LA represents lauryl acrylate, LMA represents lauryl methacrylate, n-DA represents n-decyl acrylate, MA represents myristyl acrylate, PDA represents pentadecyl acrylate, PA represents palmityl acrylate, n-OA represents n-octyl acrylate, and AA represents acrylic acid, and the numerical values ​​for these compounds represent the number of parts of each monomer.

[0095] <Manufacturing example of magnetic material B1> An aqueous solution containing ferrous hydroxide was prepared by mixing 1.0 equivalent of caustic soda solution (containing 1% by mass of sodium hexametaphosphate, calculated as P relative to Fe) with an aqueous ferrous sulfate solution. While maintaining the pH of the aqueous solution at 9, air was blown in and an oxidation reaction was carried out at 75°C until the ferrous hydroxide was completely consumed, preparing a slurry solution for producing seed crystals. Next, an aqueous solution of ferrous sulfate was added to the slurry in an amount equivalent to 1.0 relative to the initial alkali amount (sodium content of caustic soda). The pH of the slurry was maintained at 8, and air was blown into the slurry to carry out an oxidation reaction at 75°C until the ferrous sulfate was completely consumed. The pH was adjusted to 6, washed with water, and dried to obtain magnetic iron oxide spherical magnetite particles with a number average particle size of 200 nm for primary particles and a standard deviation of the number average particle size of 72 nm. 10.0 kg of the magnetic iron oxide obtained above was added to a Simpson Mix Mara (manufactured by Shin-Nitto Kogyo Co., Ltd., model MSG-0L) and crushed for 30 minutes. Thereafter, 95 g of n-decyltrimethoxysilane was added as a silane coupling agent to the apparatus, and the apparatus was operated for 1 hour to surface treat the surface of the magnetic iron oxide particles with the silane coupling agent, thereby obtaining magnetic material B1.

[0096] <Manufacturing examples of magnetic materials B2 to B6 and B9> Magnetic substances B2 to B6 and B9 were obtained in the same manner as in the production example of magnetic substance B1, except that the type of surface treatment agent used was changed as shown in Table 2. [Table 2] In the table, carbon number C M is a value determined by carrying out the above-mentioned method for identifying alkyl groups on the surface of each magnetic material on each magnetic material.

[0097] <Manufacturing example of magnetic material B7> Magnetic substance B7 was obtained in the same manner as in the production example of magnetic substance B1, except that the temperature of the oxidation reaction was changed to 85°C.

[0098] <Manufacturing example of magnetic material B8> Magnetic body B8 was obtained in the same manner as in the manufacturing example of magnetic body B1, except that a Henschel mixer (model FM-10, manufactured by Nippon Coke & Engineering Co., Ltd.) was used instead of a Simpson-Mixmar as the equipment for the crushing and hydrophobic treatment, and alkyl-modified silicone oil was used instead of alkylalkoxysilane as the surface treatment agent.

[0099] <Toner 1 manufacturing example> [Example of toner production using the pulverization method] Binder resin A1 100.0 parts ·Magnetic material B1 65.0 parts Ester compound 5.0 parts (Ethylene glycol distearate) Hydrocarbon wax 5.0 parts (Fischer-Tropsch wax, melting point 77°C) Charge control agent 1.0 parts (T-77: Manufactured by Hodogaya Chemical Industry Co., Ltd.) The above materials were premixed in an FM mixer (manufactured by Nippon Coke and Engineering Co., Ltd.) and then rotated at a speed of 3.33 s. -1 The temperature setting was adjusted so that the temperature of the kneaded mixture near the outlet of the kneaded mixture was 120°C, and the mixture was kneaded using a twin-screw kneading extruder (Model PCM-30 manufactured by Ikegai Iron Works Co., Ltd.) set at 40°C. The resulting kneaded material was cooled, coarsely pulverized with a hammer mill, and then crushed into powder using a mechanical pulverizer (Turbo Kogyo Co., Ltd. The powder was pulverized using a T-250 (manufactured by Hosokawa Micron Corporation), and the resulting finely pulverized powder was classified using a multi-division classifier utilizing the Coanda effect. Surface modification was then performed using a Faculty F-300 (manufactured by Hosokawa Micron Corporation). The operating conditions were a classifying rotor rotation speed of 130 s -1 , distributed rotor rotation speed 120s -1 As a result, toner particles having a weight average particle size (D4) of 8.0 μm and a circularity of 0.943 were obtained. For 100 parts of the toner particles, hydrophobic treated silica fine particles [BET specific surface area 150 m 2 1.2 parts of silica particles (100 parts per 100 parts of silica fine particles, hydrophobized with 30 parts of dimethyl silicone oil (100CS)) were externally added and mixed in an FM mixer (FM-75 model, manufactured by Nippon Coke & Engineering Co., Ltd.), and the mixture was sieved through a mesh with 150 μm openings to obtain Toner 1. The toner physical properties are shown in Table 4.

[0100] <Production examples of toners 2-5, 8-20, 23, 25-28, and 35> In the manufacturing example of Toner 1, the toner was manufactured in the same manner except that the formulation was changed as shown in Table 3. Toner physical properties are shown in Table 4.

[0101] <Production example of toners 6 and 7> In the production example of Toner 1, the rotation speed of the twin-screw kneading extruder was set to 2.5 s -1 The temperature was set to 150° C. and the temperature setting was adjusted so that the temperature of the kneaded product near the outlet was 150° C., and toners 6 and 7 were obtained in the same manner except for changing the formulation as shown in Table 3. The toner physical properties are shown in Table 4.

[0102] <Toner 21 manufacturing example> Toner 21 was obtained in the same manner as in the production example of Toner 1, except that the surface modification treatment was not carried out. Table 4 shows the physical properties of the toner.

[0103] <Toner 24 manufacturing example> Toner 24 was obtained in the same manner as in the production example of Toner 1, except that the external additive was changed to hydrophobized silica fine particles (BET specific surface area 150 m / g, hydrophobized with 20 parts of HMDS hexamethyldisilazane per 100 parts of silica fine particles). The toner physical properties are shown in Table 4.

[0104] <Production Example of Toners 29 to 34> In the manufacturing example of toner 1, no surface modification treatment was performed, and the external additive was hydrophobic treated silica fine particles [BET specific surface area 150 m 2 / g, hydrophobized with 20 parts of HMDS hexamethyldisilazane per 100 parts of silica fine particles], and toners 29 to 34 were obtained in the same manner except for changing the formulation as shown in Table 3. The toner physical properties are shown in Table 4. [Table 3] [Table 4] In Table 4, the unit of SP value is (J / cm 3 ) 1 / 2 and CV is the coefficient of variation of the occupied area ratio of the magnetic material.

[0105] <Production Example of Toner 22> [Example of toner production using emulsion aggregation method] (Preparation of binder resin dispersion) Binder resin A1 was dissolved in 150.0 parts of toluene and then added to 300 parts of ion-exchanged water, followed by the addition of 1.0 part of an anionic surfactant (Neogen RK, Daiichi Kogyo Seiyaku Co., Ltd.) and stirring with a homogenizer (IKA Ultra-Turrax T50). The toluene was then separated by distillation to obtain a binder resin dispersion. The solids concentration in resin particle dispersion D1 was adjusted to 25.0% by mass by adding ion-exchanged water. (Preparation of Wax Dispersion) Ester compound 25.0 parts (Ethylene glycol distearate) Hydrocarbon wax 25.0 parts (Fischer-Tropsch wax, melting point 77°C) Anionic surfactant 0.3 parts (NEOGEN RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 150.0 parts ion-exchanged water The above materials were mixed and heated to 95°C, and dispersed using a homogenizer (Ultra Turrax T50, manufactured by IKA).Then, a dispersion process was carried out using a Manton-Gaulin high-pressure homogenizer (manufactured by Gaulin) to prepare a wax dispersion (solid concentration: 25.0% by mass) in which wax particles were dispersed. (Preparation of magnetic material dispersion) ·Magnetic material B1 25.0 parts 75.0 parts ion-exchanged water The above materials were mixed and homogenized using a homogenizer (IKA Ultra Turrax T50) for 133.3 seconds. -1 The mixture was dispersed for 10 minutes at 40°C, to obtain a magnetic dispersion liquid with a magnetic fine particle concentration of 25.0% by mass.

[0106] (Toner manufacturing) ·Resin particle dispersion (solid content 25.0% by mass) 150.0 parts Wax dispersion (solid content 25.0% by mass) 15.0 parts ·Magnetic material dispersion (solid content 25.0% by mass) 97.5 parts The above materials were placed in a beaker, and the total amount of water was adjusted to 250 parts, and the temperature was adjusted to 30.0°C. Then, a homogenizer (Ultra Turrax T50, manufactured by IKA) was used to mix the materials at 83.3°C. -1 The mixture was mixed by stirring at RT for 1 minute. Furthermore, 10.0 parts of a 2.0 mass % aqueous solution of magnesium sulfate was gradually added as a flocculant. The raw material dispersion was transferred to a polymerization vessel equipped with a stirrer and a thermometer, and the mixture was heated to 50.0°C with a mantle heater and stirred to promote the growth of aggregated particles. After 60 minutes had elapsed, 200.0 parts of a 5.0 mass % aqueous solution of ethylenediaminetetraacetic acid (EDTA) was added to prepare aggregated particle dispersion 1. Subsequently, the pH of Aggregated Particle Dispersion 1 was adjusted to 8.0 using a 0.1 mol / L aqueous solution of sodium hydroxide, and then Aggregated Particle Dispersion 1 was heated to 80.0° C. and left for 180 minutes to allow the aggregated particles to coalesce. After 180 minutes, a toner particle dispersion liquid was obtained. After cooling at a temperature drop rate of 1.0°C / min, the toner particle dispersion liquid 1 was filtered and washed with ion-exchanged water. When the conductivity of the filtrate reached 50 mS or less, the toner particles that had formed into a cake were removed. Next, the cake-like toner particles were placed in ion-exchanged water in an amount 20 times the mass of the toner particles, stirred with a three-one motor, and once the toner particles were sufficiently loosened, filtered again and washed with water to separate the solid and liquid. The resulting cake-like toner particles were crushed in a sample mill and dried in an oven at 40°C for 24 hours. The resulting powder was then crushed in a sample mill and further vacuum dried in an oven at 40°C for 5 hours to obtain magnetic toner particles. For 100 parts of the magnetic toner particles, hydrophobic treated silica fine particles [BET specific surface area 150 m 2 / g, 100 parts of silica fine particles and 1.2 parts of hydrophobized dimethyl silicone oil (100CS) were externally added and mixed in an FM mixer (FM-75 model manufactured by Nippon Coke & Engineering Co., Ltd.), and the mixture was sieved through a mesh with 150 μm openings to obtain Toner 22. The toner physical properties are shown in Table 4.

[0107] <Toner 35 manufacturing example> Toner 35 was obtained in the same manner as in the production example of Toner 22, except that the prepared magnetic material dispersion was subjected to the following pre-aggregation process. The physical properties of the toner are shown in Table 4. (Pre-aggregation process) ·Magnetic material dispersion (solid content 25.0% by mass) 105.0 parts The above materials were placed in a beaker, the temperature was adjusted to 30.0°C, and then the mixture was mixed for 83.3 seconds using a homogenizer (IKA Ultra Turrax T50). -1 The mixture was stirred at RT for 1 minute, and then 1.0 part of a 2.0 mass % aqueous solution of magnesium sulfate was gradually added as a flocculant, followed by stirring for 1 minute.

[0108] <Examples 1 to 28 and Comparative Examples 1 to 7> The following evaluations were carried out using Toners 1 to 35. The evaluation results are shown in Table 5. For the evaluation, an HP LaserJet Enterprise M609dn was used with its process speed modified to 410 mm / sec. The evaluation paper was Vitality (Xerox, basis weight 75 g / cm 2 , letter size) was used. Hereinafter, Examples 25 to 28 will be referred to as Reference Examples 25 to 28, respectively.

[0109] <Low temperature fixability evaluation> For the rubbing test, the fixing unit of the evaluation machine was taken outside, and an external fixing unit was used which was modified so that the temperature of the fixing unit could be set arbitrarily and the process speed was set to 410 mm / sec. Using the above device, the toner amount per unit area was set to 0.5 mg / cm under normal temperature and humidity conditions (temperature 25°C, humidity 50% RH). 2 The unfixed solid black image was passed through a fixing unit whose temperature was adjusted to the set temperature. The resulting fixed image was fixed at 4.9 kPa (50 g / cm 2 The image was rubbed back and forth five times with Silbon paper under a load of 1000 kJ / cm², and the temperature at which the density loss before and after the rubbing test was 10% or less was defined as the fixing temperature. A temperature of C or higher was considered to be good. Image density was measured using a Macbeth densitometer (manufactured by Macbeth) which is a reflection densitometer, with an SPI filter. (Evaluation criteria) A: Fixing temperature is less than 200°C B: Fixing temperature is 200°C or higher and less than 210°C C: Fixing temperature is 210°C or higher and less than 220°C D: Fixing temperature is 220°C or higher

[0110] <Abrasion resistance evaluation> For the evaluation of abrasion resistance, the fixing device of the above-mentioned evaluation machine was taken outside, and an external fixing device was used which was modified so that the temperature of the fixing device could be set arbitrarily and the process speed was set to 450 mm / sec. Fixing was performed at the fixing temperature of each toner obtained in the above-mentioned low-temperature fixability evaluation. Toner loading: 0.50mg / cm 2 After obtaining a solid black unfixed image, the external fixing device was set to the fixing temperature of each toner, and fixing was performed in a normal temperature and humidity environment (temperature 25°C, humidity 50% RH). The obtained fixed image was fixed at 4.9 kPa (50 g / cm 2 A portion of the blank evaluation paper was cut out (rubbing paper) and rubbed back and forth 10 times while applying a load of C or higher. The reflection density of the rubbing paper after rubbing and the blank evaluation paper remaining after cutting out the rubbing paper were measured using a reflectometer (Reflectometer Model TC-6DS, manufactured by Tokyo Denshoku Co., Ltd.), and the rub resistance of the fixed image was evaluated based on the difference in reflection density. A rating of C or higher was considered good. (Evaluation criteria) A: Reflection density difference is less than 1.0 B: Reflection density difference is 1.0 or more and less than 2.0 C: Reflection density difference is 2.0 or more and less than 3.0 D: Reflection density difference is 3.0 or more

[0111] <Evaluation of missing fixation spots> For the evaluation of fixing dropouts, the fixing unit of the evaluation machine was removed to the outside, and an external fixing unit was used which was modified so that the temperature of the fixing unit could be set arbitrarily and the process speed was set to 450 mm / sec. Using the above device, in a low temperature and low humidity environment (temperature 15°C, humidity 10% RH), the toner amount per unit area was set to 1.0 mg / cm 2The unfixed solid black images were passed through a fixing unit set to the fixing temperature of each toner. The resulting images were visually inspected, and the number of areas where the toner was not fixed properly and the toner spots were counted. The fixed spots were evaluated according to the following criteria. A grade of C or higher was considered good. (Evaluation criteria) A: The number of missing pieces is less than 4. B: The number of missing pieces is 4 or more and less than 8. C: The number of missing pieces is 8 or more and less than 12. D: The number of missing pieces is 12 or more.

[0112] <Drum fusion evaluation> The drum fusion evaluation was carried out using the above evaluation machine under a high temperature and high humidity environment (temperature 30°C, humidity 80% RH). After continuously printing 20,000 sheets of horizontal line patterns with a printing rate of 5%, the toner amount per unit area was adjusted to 1.0 mg / cm. 2 A solid black image was output, and the photosensitive drum surface and the solid black image were visually inspected. The drum fusion was evaluated according to the following criteria. A grade of C or higher was judged to be good. (Evaluation criteria) A: No toner fusion was observed on the photoreceptor. B: A slight amount of toner fusion is observed on the photosensitive member, but it does not appear on the image. C: White dots are missing from the image on a solid black image. D: Shooting star-shaped image voids are observed from white dots on a solid black image.

[0113] <Evaluation of heat-resistant storage stability> A 100 mL resin cup containing 5.0 g of the toner sample was left standing in a high-temperature environment (50°C, 50% RH) for three days. It was then transferred to a room-temperature, normal-humidity environment (25°C, 50% RH) and left standing for one hour. The remaining toner amount was measured using a "Powder Tester PT-X" (manufactured by Hosokawa Micron Corporation) with a 75 μm mesh sieve under a room-temperature, normal-humidity environment (23°C, 50% RH). The sieve amplitude was adjusted to 1.00 mm (peak-to-peak), and the toner sample was placed on the sieve and vibrated for 40 seconds. The heat-resistant storage stability was then evaluated based on the amount of toner aggregates remaining on the sieve. The heat-resistant storage stability was evaluated according to the following criteria. A rating of C or higher was considered good. (Evaluation criteria) A: The amount of toner remaining on the mesh is 0.20g or less. B: The amount of toner remaining on the mesh is more than 0.20 g and 0.40 g or less. C: The amount of toner remaining on the mesh is more than 0.40 g and 0.60 g or less. D: The amount of toner remaining on the mesh exceeds 0.60g. [Table 5] In Table 5, the low-temperature fixability values ​​indicate the fixation temperature (°C), the abrasion resistance values ​​indicate the reflection density difference, the fixation defect values ​​indicate the number of defected toner particles, and the heat resistance storage properties indicate the amount of toner remaining on the mesh (g).

Claims

1. A magnetic toner having toner particles containing a binder resin and a magnetic material, the binder resin contains a styrene-acrylic resin, The styrene-acrylic resin has a monomer unit represented by the following formula (1): 【Chemical 1】 R in the formula (1) １ represents a hydrogen atom or a methyl group, R in the formula (1) ２ is the number of carbon atoms C Ｂ represents a linear alkyl group of the formula The C Ｂ is an integer between 10 and 15, The magnetic material has a carbon number C Ｍ and having an alkyl group of the formula: The C Ｍ is an integer between 4 and 20, The C Ｂ and the C Ｍ satisfies the following formula (3), |C Ｍ -C Ｂ |≦10 ・・・(3) When a cross section of the magnetic toner is observed using a transmission electron microscope and the cross section is divided into square grids each having a side length of 0.8 μm, the coefficient of variation of the occupied area ratio of the magnetic material in the square grid is 80.0% or less; the toner particles further contain an ester compound, The ester compound is selected from the group consisting of an ester compound represented by the following formula (6), an ester compound represented by the following formula (7), and an ester compound represented by the following formula (8): at least one ester compound, 【Chemistry 2】 R 31 and R 41 in the formula (6), the formula (7), and the formula (8) each independently represent an alkylene group having from 2 to 8 carbon atoms; A magnetic toner characterized in that R 32 , R 33 , R 42 , R 43 , R 51 and R 52 in the formulas (6), (7) and (8) each independently represent a linear alkyl group having 14 to 24 carbon atoms.

2. 2. The magnetic toner according to claim 1, wherein the content of the monomer unit represented by formula (1) in the styrene-acrylic resin is 1.0% by mass or more and 15.0% by mass or less.

3. Said C Ｂ 3. The magnetic toner according to claim 1, wherein the molecular weight of the toner is 12.

4. Said C Ｍ and the above C Ｂ satisfies the following formula (4): |C Ｍ -C Ｂ |≦8 ・・・(4) The magnetic toner according to any one of claims 1 to 3.

5. 5. The magnetic toner according to claim 1, wherein the coefficient of variation is 60.0% or less.

6. 6. The magnetic toner according to claim 1, wherein the thermal conductivity of the toner measured by a hot disk method is 0.190 W / mK or more.

7. The magnetic toner contains an external additive, the styrene-acrylic resin has a monomer unit represented by the following formula (5) and a monomer unit corresponding to n-butyl acrylate, 【Chemistry 3】 In formula (5), R 61 represents a hydrogen atom or a methyl group; the content of the monomer unit represented by formula (1) in the styrene-acrylic resin is 1.0 mass% or more and 10.0 mass% or less, the average circularity of the magnetic toner is 0.940 or more and 0.995 or less; the external additive comprises silicone oil-treated silica, the magnetic material is a surface-treated product that has been surface-treated with a compound having an alkyl group having a carbon number of C M ; The magnetic toner according to any one of claims 1 to 6.

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