JP2012189815A - Toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner which can obtain excellent material dispersibility even with low-viscosity resin and does not cause drum filming even over long-term use.SOLUTION: The toner comprises toner particles containing at least magnetic iron oxide particles as a colorant, and a binder resin. In a DSC curve measured with a differential scanning calorimeter, the binder resin exhibits a first endothermic peak at temperature 55-75°C, and a second endothermic peak at temperature 80-120°C. The magnetic iron oxide particles have the oil absorption amount of 15-40 ml/100 g.

Description

  The present invention relates to a toner used in an image forming method for visualizing an electrostatic charge image in electrophotography.

Conventionally, a number of methods are known as electrophotographic methods. Generally, a charging process for charging an electrostatic charge image carrier using a photoconductive substance, and electrostatic charging on the charged electrostatic charge image carrier. A step of forming a latent image, a developing step of transferring the toner carried on the toner carrier onto the electrostatic latent image for visualization, and a transfer for transferring the developed image to a transfer material by a transfer means Through the process and the fixing process of heating and fixing the transferred image transferred onto the transfer material, the target fixed matter is obtained.
In recent years, there has been a great demand for energy saving, and various toners have been proposed in order to improve the low-temperature fixing performance of the toner. In particular, in recent years, for example, a toner that improves low-temperature fixability by adding a low-melting crystalline polyester as shown in Patent Document 1 has been proposed. However, in order to further improve the low-temperature fixability, it is necessary to lower the melting point of the crystalline polyester. In such a case, for example, in a so-called “pulverized toner” that can be obtained by hot-melt kneading a material containing a binder resin and a colorant, cooling and solidifying, and then pulverizing and classifying, the viscosity is too low at the time of melt-kneading. A large share cannot be given, and the mixing property (dispersibility) between the binder resin and other materials such as a colorant tends to be remarkably lowered. As a result, the material is localized, and so-called “empty balls” that do not contain a colorant, for example, are generated in the toner particles.
If this empty ball exists in a magnetic one-component developing device using magnetic iron oxide particles as a colorant, for example, the magnetic binding force will not be exerted. It is rubbed by the member, and drum filming and the like are likely to occur. This phenomenon is particularly remarkable in a toner using a low viscosity resin.
In order to eliminate such localization of raw materials, proposals for improving the raw material dispersibility have been made. For example, Patent Document 2 proposes magnetic iron oxide particles for a magnetic toner using a binder resin having a weight average molecular weight of 150,000 or less. According to this proposal, there is a description that the dispersibility of the magnetic iron oxide particles is improved if the oil absorption amount and the compressibility of the magnetic iron oxide particles are set within a specific range. However, in the evaluation of the examples, only evaluation with two types of binder resins having a weight average molecular weight of 110,000 and 300,000 is performed. Therefore, when a lower molecular weight binder resin is used, further optimization of both the binder resin and the magnetic iron oxide particles is necessary.

Japanese Patent No. 3963673 Japanese Patent No. 3148311

  An object of the present invention is to provide a toner that solves the above problems. That is, an object of the present invention is to provide a toner that can obtain good material dispersibility even when a low-viscosity resin is used, and that does not cause drum filming even after long-term use. .

The present invention for solving the above problems is a toner having toner particles containing at least a binder resin and magnetic iron oxide particles as a colorant,
The binder resin has a first endothermic peak at a temperature of 55 ° C. to 75 ° C. and a second endothermic peak at a temperature of 80 ° C. to 120 ° C. in a DSC curve measured by a differential scanning calorimeter. The magnetic iron oxide particles are toners having an oil absorption of 15 ml / 100 g or more and 40 ml / 100 g or less.

  According to the present invention, even when a low-viscosity resin is used, good material dispersibility can be obtained, and a toner that does not cause drum filming even over a long period of use can be provided.

It is the schematic of the kneading machine used for this invention

The present inventors diligently studied the dispersibility of the material in the melt-kneading step during the production process of the magnetic toner using the pulverization method.
In the melt-kneading step, the conditions for uniformly dispersing the raw materials are as follows: the initial dispersibility of uniformly dispersing the various raw materials into the binder resin in the molten state is accelerated, and the raw materials are reused in the subsequent melt-kneading step. It is necessary to stably obtain the final dispersion which is in the final state without being agglomerated.
For that purpose, it is necessary to create an optimal molten state of the binder resin, which is the main binder, and to knead it with a mechanical share.
However, when a binder resin having a low melt viscosity is used, it is difficult to sufficiently apply the kneading share, and it is difficult to adjust the balance of the kneading share. In particular, when a binder resin that is softened at a low temperature is used with the aim of improving low-temperature fixability, the melt viscosity is likely to drop sharply, and the tendency of material dispersion to become non-uniform becomes strong.
Therefore, the present inventors, even when using a resin that softens at a low temperature and has a low viscosity, takes a sufficient kneading share, and the state of the binder resin in which the raw materials, particularly the magnetic iron oxide particles as the colorant, are well dispersed. Was examined.
As a result, in the melt-kneading process, in the process where the temperature rises, that is, before the binder resin is completely melted, there is a point where the melting characteristics change in the binder resin, so that a share is applied. It was found that the raw materials were kneaded and good dispersibility was obtained.
The fact that the resin has an endothermic peak indicates that a molten state is generated in a part of the molecule of the binder resin. By being in a molten state, a mixed state with other materials can be created. Further, at this melting point, since the binder resin is not completely melted, it is considered that a sufficient kneading share is applied and a good dispersion state can be obtained.
Furthermore, the present inventors have studied the colorant that is more effectively dispersed at the melting point of the binder resin, here, the magnetic iron oxide particles, and the optimum melting state.
In order to uniformly disperse the magnetic iron oxide particles in the binder resin, it is important that the magnetic iron oxide particles become familiar with the binder resin at the melting point. To that end, we considered that it is necessary to control the surface properties of the magnetic iron oxide particles and proceeded with the study.
And as a result of examining the surface characteristics of magnetic iron oxide particles, the present inventors have found that there is a relationship between the oil absorption and dispersibility of magnetic iron oxide particles.
Oil absorption is an index for knowing the degree of structure, which is a complex aggregation due to chemical and physical bonding of magnetic iron oxide particles, but it was considered that it could also be an index that represents the familiarity with oil components. That is, at the two melting points of the binder resin, the melted binder resin was regarded as a pseudo oil component, and an optimum oil absorption amount of the magnetic iron oxide particles that were easily adapted to the binder resin was examined.
As a result, it has been found that the oil absorption amount of the magnetic iron oxide particles is controlled to 15 ml / 100 g or more and 40 ml / 100 g or less, so that the binder resin can be effectively adapted to the melting point.
As described above, as a condition for uniformly dispersing the raw material, it is necessary to speed up the progress of initial dispersibility and stably obtain the final dispersion without reaggregation in the subsequent melt-kneading step. ,
The fact that the magnetic iron oxide particles become familiar with the binder resin indicates that the progress of initial dispersion is fast.
Furthermore, in order to stabilize the state of the final dispersion without causing re-aggregation, it is necessary to optimize the melting point of the binder resin, and the present inventors have determined the number of binder resin melting points and the temperature thereof. The area was examined.
When the melting point of the binder resin is one, the progress of dispersion of the material is not sufficient, the raw material is liable to re-aggregate, and a sufficient dispersion state cannot be obtained.
On the other hand, when the melting point of the binder resin is two, it has been found that the formation of the molten state and the kneading share can be most balanced, and the state of the final dispersion is stabilized without causing re-aggregation. Here, in the DSC curve measured by the differential scanning calorimeter of the binder resin, it has a first endothermic peak (first melting point) at a temperature of 55 to 75 ° C., and a temperature of 80 to 120 ° C. It has been found that it is necessary to have a second endothermic peak (second melting point) below.
Further, when the melting point of the binder resin is 3 or more, the viscosity of the binder resin is excessively lowered, so that the melted state and the kneading share cannot be achieved, and a sufficient dispersed state cannot be obtained.
From the above examination results, the toner of the present invention has a first endothermic peak at a temperature of 55 ° C. to 75 ° C. and a temperature of 80 ° C. to 120 ° C. in a DSC curve measured by a differential scanning calorimeter. By using toner particles containing a binder resin having an endothermic peak of 2 and magnetic iron oxide particles having an oil absorption of 15 ml / 100 g or more and 40 ml / 100 g or less, formation of a molten state in the toner particle production process And kneading that took a lot of share. As a result, it is possible to provide a toner that does not cause drum filming even over a long period of use.
That is, the present invention is a toner having toner particles containing at least a binder resin and magnetic iron oxide particles as a colorant,
The binder resin has a first endothermic peak (hereinafter also referred to as an endothermic peak P1) at a temperature of 55 ° C. to 75 ° C. (preferably a temperature of 55 ° C. to 70 ° C.) in a DSC curve measured by a differential scanning calorimeter. And a second endothermic peak (hereinafter also referred to as an endothermic peak P2) at a temperature of 80 ° C. or higher and 120 ° C. or lower (preferably a temperature of 85 ° C. or higher and 115 ° C. or lower). The oil absorption is 15 ml / 100 g or more and 40 ml / 100 g or less (preferably 24 ml / 100 g or more and 36 ml / 100 g or less).

By the way, many materials having an endothermic peak as described above exist as materials used for toner. For example, waxes which are release agents, crystalline resins (crystalline polyester, etc.) and the like can be mentioned. These materials are generally added separately from the binder resin as an additive. Therefore, for example, when a release agent having an endothermic peak in the same temperature range as the binder resin used in the present invention, or a crystalline resin is added to a conventionally known binder resin, the additive itself has a predetermined content. Although it melts at temperature, the binder resin itself does not melt. Therefore, although a molten state is created in the vicinity of the release agent and the crystalline resin, it is difficult to obtain a uniform dispersed state as a whole including the binder resin as the main binder.
On the other hand, the binder resin of the present invention has two melting points in the same molecule in the binder resin. Therefore, at each melting temperature, starting from the melting point, the entire binder resin is temporarily in a semi-molten state and is expected to obtain uniform dispersion as a whole by mixing with other materials. That is, it is possible to achieve both the formation of the molten state and the kneading by multiplying the kneading share. The above is the skeleton of the present invention.

Hereinafter, the present invention will be described in more detail.
In the binder resin of the present invention, the endothermic amount of the first endothermic peak in the DSC curve measured by the differential scanning calorimeter is ΔH1, and the endothermic amount of the second endothermic peak in the DSC curve measured by the differential scanning calorimeter. Is preferably ΔH2, ΔH1 and ΔH2 preferably satisfy the relationship ΔH1 ≦ ΔH2.
Since the endothermic amount of the endothermic peak represents the amount of change when the molecule changes, the larger the endothermic amount, the easier the whole molecule moves. By making the endothermic amount ΔH1 at the first endothermic peak in the lower temperature region smaller than the endothermic amount ΔH2 at the second endothermic peak, the orientation of the magnetic iron oxide particles is also aligned. For this reason, magnetic iron oxide particles are preferable because they exhibit good dispersibility and, as a result, improve the blackness of the toner.
Furthermore, in the binder resin of the present invention, the endothermic amount ΔH1 of the first endothermic peak is preferably 0.20 J / g or more and 1.50 J / g or less, more preferably 0.25 J / g or more, 1.20 J / g or less. The endothermic amount ΔH2 of the second endothermic peak is preferably 0.20 J / g or more and 2.00 J / g or less, more preferably 0.50 J / g or more and 1.80 J / g or less. .
Moreover, in the said endothermic peak, it is preferable that a 1st endothermic peak is a peak derived from the phenomenon (enthalpy relaxation) which eases the energy which the high molecular body which occurs after the glass transition temperature of binder resin had excessively. .
Enthalpy relaxation indicates the force by which the molecules try to move immediately after the binder resin undergoes a phase transition from the glassy state to the supercooled liquid. Therefore, it is preferable to have an endothermic peak due to enthalpy relaxation at the first endothermic peak because it becomes easier to achieve both the formation of the molten state and the kneading with the share.
The numerical values of the first endothermic peak, the second endothermic peak, and the endothermic amounts ΔH1 and ΔH2 can be adjusted by changing the monomer composition ratio and molecular weight of the binder resin.
In addition, it is preferable to set the endothermic amount of each endothermic peak in the above range because the blackness of the toner becomes more stable.

On the other hand, the magnetic iron oxide particles of the present invention preferably have a BET specific surface area (hereinafter also simply referred to as BET) of 7.0 m ² / g or more and 13.0 m ² / g or less, more preferably 9.0 m. ^{It is 2} / g or more and 11.0 m ² / g or less. By controlling the BET specific surface area of the magnetic iron oxide particles within the above range, the number of magnetic iron oxide particles present on the surface of the toner particles becomes appropriate, the charging property is stable, and the fog due to durability is improved, which is preferable. .
The shape of the magnetic iron oxide particles used in the present invention is preferably a polyhedron. It is preferable to make the shape of the magnetic iron oxide particles polyhedral so that the adhesion to the binder resin is increased and the release of the magnetic iron oxide particles from the toner particles can be suppressed even in a high-speed development system.
In addition, the number average primary particle size (hereinafter sometimes simply referred to as particle size) of the magnetic iron oxide particles used in the present invention is preferably 0.10 μm or more and 0.50 μm or less, preferably 0.10 μm or more, More preferably, it is 0.30 μm or less. By making it in the same range, the chargeability becomes more stable, which is preferable.
In addition, in order for the magnetic iron oxide particles of the present invention to make the developability more stable, the saturation magnetization (σs) at a measurement magnetic field of 795.8 kA / m is 70 Am ² / kg or more and 95 Am ² / kg or less. Is more preferable, and 80 Am ² / kg or more and 90 Am ² / kg or less are more preferable.

Further, the physical properties of the toner of the present invention preferably have the following viscoelastic properties.
That is, in the viscoelastic characteristics measured at a toner frequency of 6.28 rad / sec, the storage elastic modulus (G′40) at a temperature of 40 ° C. is preferably 7.0 × 10 ⁸ Pa or more and 2.0 × 10 ^9. The storage elastic modulus (G′70) at a temperature of 70 ° C. is preferably 1.0 × 10 ⁵ Pa or more and 1.0 × 10 ⁷ Pa or less, more preferably 1.0 × 10 ^5. Pa to 5.0 × 10 ⁶ Pa or less.
The storage elastic modulus of the toner indicates the so-called elastic component, which is the ability of the toner to retain the stress stored therein at that temperature. The binder resin used in the present invention has endothermic peaks in two temperature ranges, but the storage elastic modulus (G′40) at a temperature of 40 ° C. and the storage elastic modulus (G′70) at a temperature of 70 ° C. are constant. By controlling in this range, it is preferable because a better dispersion state can be stably maintained for a long time.

The binder resin used in the present invention, that is, the binder resin having two endothermic peaks in a predetermined temperature range is obtained by, for example, orienting a part of a molecular chain and creating a crystalline part in the same molecule. Can be produced. In this respect, the binder resin used in the present invention is preferably a polyester resin, and among them, a linear polyester is particularly preferable. The components of the linear polyester resin particularly preferably used in the present invention are as follows.
Examples of the divalent acid component constituting the polyester resin include the following dicarboxylic acids or derivatives thereof. Benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride or their anhydrides or lower alkyl esters thereof; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, azelaic acid or their anhydrides or lower thereof Alkyl esters; alkenyl succinic acids or alkyl succinic acids such as n-dodecenyl succinic acid, n-dodecyl succinic acid, or anhydrides thereof or lower alkyl esters thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, itaconic acid Or its anhydride or its lower alkyl ester.
Since the binder resin used in the present invention is characterized in that it has crystallinity by orienting a part of the polymer chain, it has a solid planar structure as an acid component constituting the polyester resin, and π Aromatic dicarboxylic acids that are easily molecularly oriented by π-π interaction are preferred due to the abundance of electrons delocalized by the electron system. Particularly preferred are terephthalic acid and isophthalic acid, which are easily linear. From the viewpoint of controlling the temperature of the endothermic peak, the content of the aromatic dicarboxylic acid is preferably 50 mol% or more, more preferably 70 mol% or more, in 100 mol% of all acid components constituting the polyester resin. More preferably, it is 90 mol% or more.
On the other hand, the following are mentioned as a bivalent alcohol component which comprises a polyester resin. Ethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanedimethanol (CHDM) Hydrogenated bisphenol A, bisphenol represented by the following formula (1) and derivatives thereof: and diols represented by the following formula (2).

（式中、Ｒはエチレンまたはプロピレン基であり、ｘ、ｙはそれぞれ０以上の整数であり、かつ、ｘ＋ｙの平均値は０乃至１０である。）

(In the formula, R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x + y is 0 to 10.)

Among these, a straight chain aliphatic alcohol having 2 to 6 carbon atoms, which can easily form a straight chain structure, is preferable from the viewpoint of aligning a part of the molecule and imparting crystallinity. The content of the linear aliphatic alcohol is preferably 40 mol% or more, and more preferably 50 mol% or more, in 100 mol% of all alcohol components constituting the polyester resin.
However, this alone increases the crystallinity and the amorphous nature is lost. Therefore, in order to partially destroy the crystal structure of the polyester resin obtained by the combination of the acid and the alcohol and to have two endothermic peaks in the same molecule, the crystallinity is destroyed sterically while taking a linear structure. At least one selected from the group consisting of neopentyl glycol, 2-methyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, and the like having a substituent in the side chain capable of However, in 100 mol% of all the alcohol components which comprise a polyester resin, Preferably it is 10 mol% or more, More preferably, it is 20 mol% or more.
The polyester resin used in the present invention is a monovalent carboxylic acid component, a monovalent alcohol component, a trivalent or higher carboxylic acid component, a trivalent or higher, in addition to the above divalent carboxylic acid component and divalent alcohol component. The alcohol component may be contained as a constituent component.
Examples of the monovalent carboxylic acid component include aromatic carboxylic acids having 30 or less carbon atoms such as benzoic acid and p-methylbenzoic acid, and aliphatic carboxylic acids having 30 or less carbon atoms such as stearic acid and behenic acid. .
Examples of the monovalent alcohol component include aromatic alcohols having 30 or less carbon atoms such as benzyl alcohol, and aliphatic alcohols having 30 or less carbon atoms such as lauryl alcohol, cetyl alcohol, stearyl alcohol, and behenyl alcohol. It is done.
Although it does not restrict | limit especially as a trivalent or more carboxylic acid component, Trimellitic acid, trimellitic anhydride, pyromellitic acid, etc. are mentioned.
Examples of the trivalent or higher alcohol component include trimethylolpropane, pentaerythritol, and glycerin.
Here, as the binder resin used in the present invention, in addition to the polyester resin, a binder resin constituting a known toner can be contained to the extent that the effects of the present invention are not impaired.

About the manufacturing method of the said polyester resin, it does not restrict | limit in particular, A well-known method can be used. For example, the above-mentioned carboxylic acid component and alcohol component are charged together and polymerized through an esterification reaction or a transesterification reaction and a condensation reaction to produce a polyester resin. In the polymerization of the polyester resin, for example, a polymerization catalyst such as titanium tetrabutoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium dioxide or the like can be used. The polymerization temperature is not particularly limited, but is preferably in the range of 180 to 290 ° C.
The softening point of the binder resin used in the present invention is a constant load extrusion type capillary rheometer from the viewpoint of low temperature fixability, and the softening point temperature (Tm) calculated by the method described later is 70 ° C. As mentioned above, it is preferable that it is 120 degrees C or less. Furthermore, the binder resin used in the present invention has at least one peak in the molecular weight region of 5000 to 10,000 in the molecular weight distribution measured by gel permeation chromatography (GPC) soluble in tetrahydrofuran (THF). Is preferred.

The magnetic iron oxide particles used in the present invention are not particularly limited as long as the oil absorption is controlled within a specified range, but iron oxides such as magnetite, maghemite, and ferrite are preferably used. The method for producing magnetic iron oxide particles used in the present invention is not particularly problematic even if a general production method is used, but a preferred production method will be specifically described below.
The magnetic iron oxide particles used in the present invention are a method of producing magnetic iron oxide particles by oxidizing a ferrous hydroxide slurry obtained by neutralizing and mixing a ferrous salt aqueous solution and an alkaline solution. .
What can be utilized as a ferrous salt will not be specifically limited if it is water-soluble salt like ferrous sulfate or ferrous chloride.
Next, the ferrous hydroxide aqueous solution and the alkali solution are neutralized and mixed to produce a ferrous hydroxide slurry. Here, an alkali hydroxide aqueous solution such as sodium hydroxide or potassium hydroxide aqueous solution can be used as the alkaline solution. What is necessary is just to adjust the amount of alkali solutions at the time of producing | generating a ferrous hydroxide slurry according to the shape of the magnetic iron oxide particle to obtain | require. In order to obtain magnetic iron oxide particles from the ferrous hydroxide slurry thus obtained, an oxidation reaction is performed while blowing a conventional oxygen-containing gas, preferably air, into the slurry. Here, if necessary, a coating layer containing various metal elements may be formed on the surface of the obtained core particles.
The obtained slurry of magnetic iron oxide particles is subjected to conventional filtration, washing, drying, and pulverization to obtain magnetic iron oxide particles.
In particular, in the present invention, the oil absorption of the magnetic iron oxide particles can be adjusted by controlling the shape of the magnetic iron oxide particles, the surface treatment of the magnetic iron oxide particles, and the like. In addition, since the oil absorption of the magnetic iron oxide particles also reflects the structure of the magnetic iron oxide particles, the magnetic iron oxide particles are compressed, sheared, and spatulated using a mix muller or a raking machine. The amount of oil absorption can be adjusted by loosening.
In the present invention, the content of the magnetic iron oxide particles is preferably 20 parts by mass or more and 150 parts by mass or less, more preferably 40 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the binder resin. .

In the present invention, a release agent (wax) can be used as necessary to give the toner releasability. As the wax, hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, and paraffin wax are preferably used because of easy dispersion in toner particles and high releasability. If necessary, one or two or more kinds of waxes may be used in combination. Examples include the following:
Oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax, or block copolymers thereof; waxes based on fatty acid esters such as carnauba wax, sazol wax, and montanate ester wax; deacidified carnauba Deoxidized part or all of fatty acid esters such as wax. Furthermore, the following are mentioned. Saturated linear fatty acids such as palmitic acid, stearic acid and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid and valinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvyl alcohol, seryl alcohol, Saturated alcohols such as sil alcohols; long-chain alkyl alcohols; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide, lauric acid amide; methylene bis stearic acid amide, ethylene biscapric acid amide , Saturated fatty acid bisamides such as ethylene bislauric acid amide and hexamethylene bis stearic acid amide; ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid Amides, unsaturated fatty acid amides such as N, N-dioleyl sebacic acid amide; m-xylene bisstearic acid amide, aromatic bisamides such as N, N-distearylisophthalic acid amide; calcium stearate, calcium laurate, Fatty acid metal salts such as zinc stearate and magnesium stearate (generally called metal soap); waxes grafted with aliphatic hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid; behenine A partially esterified product of a fatty acid such as an acid monoglyceride and a polyhydric alcohol; a methyl ester compound having a hydroxyl group obtained by hydrogenation of a vegetable oil.
Examples of waxes that are particularly preferably used in the present invention include aliphatic hydrocarbon waxes. Examples of such aliphatic hydrocarbon waxes include the following. Low molecular weight alkylene polymer obtained by radical polymerization of alkylene under high pressure or Ziegler catalyst under low pressure; alkylene polymer obtained by thermally decomposing high molecular weight alkylene polymer; synthesis containing carbon monoxide and hydrogen Synthetic hydrocarbon waxes obtained from the distillation residue of hydrocarbons obtained from the gas by the age method and synthetic hydrocarbon waxes obtained by hydrogenating them; press sweating method, solvent method, vacuum Wax separated by use of distillation or fractional crystallization.
Examples of the hydrocarbon as the matrix of the aliphatic hydrocarbon wax include the following. Carbonization synthesized by the reaction of carbon monoxide and hydrogen using a metal oxide catalyst (often a multi-component system of two or more types) (for example, the Gintor method, Hydrocol method (using a fluidized catalyst bed)) Hydrogen compounds); hydrocarbons having up to about several hundred carbon atoms obtained by the age method (using an identified catalyst bed) in which a large amount of waxy hydrocarbons can be obtained; hydrocarbons obtained by polymerizing alkylene such as ethylene with a Ziegler catalyst. Among such hydrocarbons, in the present invention, it is preferable that the hydrocarbon is a linear hydrocarbon having a small number of branches and a long saturation, and particularly a hydrocarbon synthesized by a method not based on polymerization of alkylene has a molecular weight distribution. Is also preferable.
Specific examples that can be used include the following. Biscol (registered trademark) 330-P, 550-P, 660-P, TS-200 (Sanyo Chemical Industry Co., Ltd.); High Wax 400P, 200P, 100P, 410P, 420P, 320P, 220P, 210P, 110P (Mitsui Chemicals) Sazol H1, H2, C80, C105, C77 (Sazol Corporation); HNP-1, HNP-3, HNP-9, HNP-10, HNP-11, HNP-12 (Nippon Seiwa Co., Ltd.), Unilin (registered trademark) 350, 425, 550, 700, Unicid (registered trademark) 350, 425, 550, 700 (Toyo Petrolite); wood wax, beeswax, rice wax, candelilla wax, carnauba wax (Co., Ltd.) Celerica NODA).
The release agent (wax) is preferably added in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the binder resin.

In the toner of the present invention, it is preferable to use a charge control agent in order to stabilize the charging property. Although the charge control agent varies depending on the type and physical properties of other toner particle constituent materials, it is generally preferable that the toner particles are contained in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the binder resin. More preferably, it is contained in an amount of 0.1 to 5 parts by mass. As such a charge control agent, an organometallic complex or a chelate compound in which an acid group or a hydroxyl group present at the terminal of the binder resin used in the present invention and a central metal are likely to interact is effective. Examples thereof include monoazo metal complexes; acetylacetone metal complexes; metal complexes or metal salts of aromatic hydroxycarboxylic acids or aromatic dicarboxylic acids.
Specific examples that can be used include Spiron Black TRH, T-77, T-95 (Hodogaya Chemical Co., Ltd.), BONTRON (registered trademark) S-34, S-44, S-54, E-84, E- 88, E-89 (Orient Chemical). Moreover, charge control resin can also be used together with the above-described charge control agent.

In the toner of the present invention, it is preferable to externally add fine silica powder to the toner particles in order to improve charging stability, developability, fluidity and durability.
A fine silica powder used in the present invention has a specific surface area of 30 m ² / g or more (more preferably 50 m ² / g or more and 400 m ² / g or less) according to the BET method by nitrogen adsorption. . Silica fine powder is used in an amount of 0.01 to 8.00 parts by weight, preferably 0.10 to 5.00 parts by weight, based on 100 parts by weight of toner particles. The BET specific surface area of the silica fine powder is silica using, for example, a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics), GEMINI 2360/2375 (manufactured by Micrometric), or Tristar 3000 (manufactured by Micrometric). Nitrogen gas is adsorbed on the surface of the fine powder, and calculation can be performed using the BET multipoint method.
In addition, the silica fine powder used in the present invention is optionally modified with an unmodified silicone varnish, various modified silicone varnishes, unmodified silicone oil, various modified silicone oils, silane cups for the purpose of hydrophobization and tribocharging control. It is preferable to treat with a treating agent such as a ring agent, a silane compound having a functional group, or another organosilicon compound, or in combination with various treating agents.
Furthermore, other additives may be externally added to the toner of the present invention as necessary. Examples of such additives include charging aids, conductivity-imparting agents, fluidity-imparting agents, anti-caking agents, release agents at the time of heat roller fixing, lubricants, abrasives, etc. A fine powder is mentioned. For example, examples of the lubricant include polyfluorinated ethylene powder, zinc stearate powder, and polyvinylidene fluoride powder. Examples of the abrasive include cerium oxide powder, silicon carbide powder, and strontium titanate powder. Of these, strontium titanate powder is preferable.

In order to produce the toner of the present invention, a binder resin, magnetic iron oxide particles as a colorant, and, if necessary, a wax, a charge control agent, other additives, etc. are mixed in a mixer such as a Henschel mixer or a ball mill. Then, the mixture is melt-kneaded using a thermal kneader such as a twin-screw kneading extruder, heating roll, kneader, and extruder to make the resins compatible with each other. The toner particles according to the present invention can be obtained by dispersing or dissolving the metal compound, cooling and solidifying, and then performing pulverization and classification.
Furthermore, the toner according to the present invention can be obtained by sufficiently mixing a desired external additive with a mixer such as a Henschel mixer, if necessary.
The following are mentioned as a mixer. Henschel mixer (made by Mitsui Mining); Super mixer (made by Kawata); Ribocorn (made by Okawara Seisakusho); Nauta mixer, turbulizer, cyclomix (made by Hosokawa Micron); Spiral pin mixer (made by Taiheiyo Kiko) A Ladige mixer (manufactured by Matsubo).
Examples of the kneader include the following. KRC kneader (manufactured by Kurimoto Tekkosho); Bus co-kneader (manufactured by Buss); TEM type extruder (manufactured by Toshiba Machine); TEX twin-screw kneader (manufactured by Nippon Steel); PCM kneader (Ikegai) Steel mill); three roll mill, mixing roll mill, kneader (manufactured by Inoue Seisakusho); kneedex (manufactured by Mitsui Mining); MS-type pressure kneader, nider ruder (manufactured by Moriyama Seisakusho); Banbury mixer (Kobe Steel) (Made by the company).
Examples of the pulverizer include the following. Counter jet mill, micron jet, inomizer (manufactured by Hosokawa Micron); IDS type mill, PJM jet crusher (manufactured by Nippon Pneumatic Industrial Co., Ltd.); cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); SK; jet mill (manufactured by Seishin Enterprise Co., Ltd.); kryptron (manufactured by Kawasaki Heavy Industries, Ltd.); turbo mill (manufactured by Turboe Corporation); super rotor (manufactured by Nisshin Engineering Co., Ltd.).
Examples of the classifier include the following. Classifier, Micron Classifier, Spedic Classifier (manufactured by Seishin Enterprise); Turbo Classifier (manufactured by Nissin Engineering); Micron Separator, Turboplex (ATP), TSP Separator (manufactured by Hosokawa Micron); Elbow Jet (Japan) Iron Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Engineering Co., Ltd.); YM Microcut (manufactured by Yaskawa Corporation).
Examples of the sieving apparatus used for sieving coarse particles include the following. Ultrasonic (manufactured by Sakae Sangyo Co., Ltd.); Resonator Sheave, Gyroshifter (Tokusu Kosakusha Co., Ltd.); Vibrasonic System (manufactured by Dalton Co.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); Micro shifter (manufactured by Hadano Sangyo Co., Ltd.); circular vibrating sieve.
In particular, in the present invention, in order to uniformly disperse the magnetic iron oxide particles in the binder resin, it is important that the magnetic iron oxide particles are sufficiently mixed during melt kneading at the time of toner production. In the present invention, a twin-screw extrusion kneader is preferably used.
In the biaxial extrusion kneader, two rotating shafts called paddles pass through a heating cylinder that keeps the temperature constant. The raw material is supplied from one end of the heating cylinder, heated and melted while being kneaded by the rotation of the paddle and extruded from the other end. A vent hole mainly for degassing may be installed along the way. FIG. 1 shows a schematic view of an extrusion kneader preferably used in the present invention.
In order to satisfactorily perform this mixing and dispersion, it is preferable to adjust the heating set temperature during kneading. In this invention, it is preferable that the ultimate temperature of a kneaded material is 100 degreeC or more and 200 degrees C or less. If it is this temperature range, a uniform dispersion state can be obtained stably and it is preferable.

The physical property measuring method according to the present invention is as follows. Examples described later are also based on this method.
<Measurement of endothermic peak and endothermic amount of binder resin>
The peak temperatures of the first and second endothermic peaks and the endothermic amounts of the first and second endothermic peaks in the DSC curve of the binder resin are measured by the following methods. First, the peak temperature of the endothermic peak of the binder resin is measured according to ASTM D3418-82 using a differential scanning calorimeter “Q1000” (manufactured by TA Instruments).
The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium.
Specifically, about 5 mg of binder resin is precisely weighed, placed in an aluminum pan, and an empty aluminum pan is used as a reference, and the temperature is raised within a measurement temperature range of 30 to 200 ° C. Measurement is performed at a rate of 10 ° C./min. In the measurement, the temperature is once raised to 200 ° C., subsequently lowered to 30 ° C., and then the temperature is raised again. A specific heat change is obtained in this temperature rising process. At this time, the intersection of the intermediate point line of the baseline before and after the change in specific heat and the differential heat curve is defined as the glass transition temperature (Tg) of the binder resin.
The endothermic peak obtained immediately after the glass transition temperature (Tg) in the temperature range of 30 to 200 ° C. in the second temperature raising process is the first endothermic peak P1, and the endothermic peak obtained by further raising the temperature is the first endothermic peak. An endothermic peak P2 of 2. The peak temperatures of the first and second endothermic peaks are referred to as temperature P1 and temperature P2, respectively. On the other hand, the endothermic amount ΔH of the first and second endothermic peaks can be obtained by obtaining the integrated value of the endothermic peaks.

<Measurement of softening point of binder resin>
The softening point of the binder resin is measured using a constant-load extrusion type capillary rheometer “Flow Characteristic Evaluation Device Flow Tester CFT-500D” (manufactured by Shimadzu Corporation) according to the manual attached to the device. In this device, while applying a constant load from the top of the measurement sample with the piston, the measurement sample filled in the cylinder is heated and melted, and the melted measurement sample is pushed out from the die at the bottom of the cylinder. A flow curve showing the relationship between temperature and temperature can be obtained.
In the present invention, the “melting temperature in the 1/2 method” described in the manual attached to the “flow characteristic evaluation apparatus Flow Tester CFT-500D” is the softening point. The melting temperature in the 1/2 method is calculated as follows. First, ½ of the difference between the piston lowering amount (Smax) at the time when the outflow ends and the piston lowering amount (Smin) at the time when the outflow starts is obtained (this is assumed to be X. X = (Smax). -Smin) / 2). The temperature of the flow curve when the amount of piston descent in the flow curve is the sum of X and Smin is the melting temperature (Tm) in the 1/2 method.
As a measurement sample, about 1.0 g of a sample is compression-molded at about 10 MPa using a tablet molding compressor (for example, NT-100H, manufactured by NPA System) in an environment of 25 ° C. for about 60 seconds. A cylindrical shape having a diameter of about 8 mm is used.
The measurement conditions of CFT-500D are as follows.
Test mode: Temperature rising start temperature: 50 ° C
Achieving temperature: 200 ° C
Measurement interval: 1.0 ° C
Temperature increase rate: 4.0 ° C./min
Piston cross-sectional area: 1.000 cm ²
Test load (piston load): 10.0 kgf (0.9807 MPa)
Preheating time: 300 seconds Die hole diameter: 1.0 mm
Die length: 1.0mm

<Measurement of peak molecular weight (Mp) of binder resin>
The measurement of the peak molecular weight (Mp) of the binder resin is performed as shown below using GPC (gel permeation chromatography).
The column is stabilized in a heat chamber at 40 ° C., THF is flowed through the column at this temperature as a solvent at a flow rate of 1 ml / min, and about 100 μl of the THF sample solution is injected and measured.
In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count value. As a standard polystyrene sample for preparing a calibration curve, for example, a standard polystyrene sample having a molecular weight of about 1 × 10 ² to 1 × 10 ⁷ manufactured by Tosoh Corporation or Showa Denko is used. Is appropriate. The detector uses an RI (refractive index) detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, combinations of shodex GPC KF-801, 802, 803, 804, 805, 806, 807, 800P manufactured by Showa Denko KK, or manufactured by Tosoh Corporation of _{TSKgel G1000H (H XL), G2000H} (H XL), G3000H (H XL), G4000H (H XL), G5000H (H XL), G6000H (H XL), G7000H (H XL), TSKgurd
A combination of columns can be given.
Moreover, a sample is produced as follows.
Place the sample in THF and leave it at 25 ° C. for several hours, then shake it well, mix well with THF (until the sample is no longer integrated), and let stand for more than 12 hours. At that time, the standing time in THF is set to 24 hours. After that, a sample processed filter (pore size 0.2 to 0.5 μm, for example, Mysori Disc H-25-2 (manufactured by Tosoh Corporation) can be used) is used as a GPC sample. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.

<Measurement of oil absorption of magnetic iron oxide particles>
In the present invention, the linseed oil absorption of magnetic iron oxide particles is a value measured according to the method described in JIS K 5101-1978 (pigment test method).

<Measurement of shape and average primary particle diameter of magnetic iron oxide particles>
The average primary particle diameter was determined by observing magnetic iron oxide particles with a scanning electron microscope (magnification 40000 times), measuring the ferret diameter of 200 particles, and determining the number average primary particle diameter. Further, the shape of the magnetic iron oxide particles was judged from the observed image. In this example, S-4700 (manufactured by Hitachi, Ltd.) was used as the scanning electron microscope.

<Measurement of BET specific surface area of magnetic iron oxide particles>
The BET specific surface area of the magnetic iron oxide particles is measured according to JIS Z8830 (2001). A specific measurement method is as follows.
As a measuring device, an “automatic specific surface area / pore distribution measuring device TriStar 3000 (manufactured by Shimadzu Corporation)” which employs a gas adsorption method by a constant volume method as a measuring method is used. Setting of measurement conditions and analysis of measurement data are performed using dedicated software “TriStar3000 Version 4.00” attached to the apparatus, and a vacuum pump, a nitrogen gas pipe, and a helium gas pipe are connected to the apparatus. The value calculated by the BET multipoint method using nitrogen gas as the adsorption gas is defined as the BET specific surface area in the present invention.
The BET specific surface area is calculated as follows.
First, nitrogen gas is adsorbed on the magnetic iron oxide particles, and the equilibrium pressure P (Pa) in the sample cell and the nitrogen adsorption amount Va (mol · g ⁻¹ ) of the magnetic iron oxide particles are measured. The relative pressure Pr that is a value obtained by dividing the equilibrium pressure P (Pa) in the sample cell by the saturated vapor pressure Po (Pa) of nitrogen is taken as the horizontal axis, and the nitrogen adsorption amount Va (mol · g ⁻¹ ) is taken as the vertical axis. The adsorption isotherm is obtained. Next, the monomolecular layer adsorption amount Vm, which is the adsorption amount necessary to form a monomolecular layer on the surface of the magnetic iron oxide particles
(Mol · g ⁻¹ ) is obtained by applying the following BET equation.
Pr / Va (1-Pr) = 1 / (Vm * C) + (C-1) * Pr / (Vm * C)
(Here, C is a BET parameter, which is a variable that varies depending on the measurement sample type, adsorbed gas type, and adsorption temperature.)
The BET equation is interpreted as a straight line with an inclination of (C-1) / (Vm × C) and an intercept of 1 / (Vm × C), where Pr is X axis and Pr / Va (1-Pr) is Y axis. Yes (this line is called a BET plot).
Straight line slope = (C-1) / (Vm × C)
Straight line intercept = 1 / (Vm × C)
When the measured value of Pr and the measured value of Pr / Va (1-Pr) are plotted on a graph and a straight line is drawn by the least square method, the slope and intercept value of the straight line can be calculated. Vm and C can be calculated by solving the above slope and intercept simultaneous equations using these values.
Furthermore, the BET specific surface area S (m ² · g ⁻¹ ) of the magnetic iron oxide particles is calculated from the calculated Vm and the molecular occupation cross-sectional area (0.162 nm ² ) of the nitrogen molecule based on the following formula. .
S = Vm × N × 0.162 × 10 ⁻¹⁸
(N is Avogadro's number (mol ⁻¹ ).)
The measurement using this apparatus follows the “TriStar 3000 Instruction Manual V4.0” attached to the apparatus, and specifically, the measurement is performed according to the following procedure.
Thoroughly weigh the tare of a dedicated glass sample cell (stem diameter 3/8 inch, volume about 5 ml) that has been thoroughly cleaned and dried. Then, about 1.5 g of magnetic iron oxide particles are put into this sample cell using a funnel.
The sample cell containing magnetic iron oxide particles is set in a “pretreatment device Bacrepep 061 (manufactured by Shimadzu Corporation)” connected to a vacuum pump and a nitrogen gas pipe, and vacuum degassing is continued at 23 ° C. for about 10 hours. To do. During vacuum deaeration, the gas is gradually deaerated while adjusting the valve so that the magnetic iron oxide particles are not sucked into the vacuum pump. The pressure in the cell gradually decreases with deaeration and finally becomes about 0.4 Pa (about 3 mTorr). After completion of vacuum degassing, nitrogen gas is gradually injected to return the inside of the sample cell to atmospheric pressure, and the sample cell is removed from the pretreatment device. Then, the mass of the sample cell is precisely weighed, and the exact mass of the magnetic iron oxide particles is calculated from the difference from the tare. At this time, the sample cell is covered with a rubber stopper during weighing so that the magnetic iron oxide particles in the sample cell are not contaminated by moisture in the atmosphere.
Next, a dedicated “isothermal jacket” is attached to the stem portion of the sample cell containing the magnetic iron oxide particles. Then, a dedicated filler rod is inserted into the sample cell, and the sample cell is set in the analysis port of the apparatus. The isothermal jacket is a cylindrical member having an inner surface made of a porous material and an outer surface made of an impermeable material capable of sucking liquid nitrogen to a certain level by capillary action.
Subsequently, the free space of the sample cell including the connection tool is measured. The free space is measured by measuring the volume of the sample cell using helium gas at 23 ° C., and then measuring the volume of the sample cell after cooling the sample cell with liquid nitrogen using helium gas. It is calculated by converting from the difference in volume. Further, the saturated vapor pressure Po (Pa) of nitrogen is automatically measured separately using a Po tube built in the apparatus.
Next, after performing vacuum deaeration in the sample cell, the sample cell is cooled with liquid nitrogen while continuing the vacuum deaeration. Thereafter, nitrogen gas is gradually introduced into the sample cell to adsorb nitrogen molecules on the magnetic iron oxide particles. At this time, the adsorption isotherm is obtained by measuring the equilibrium pressure P (Pa) as needed, and the adsorption isotherm is converted into a BET plot. Note that the points of the relative pressure Pr for collecting data are set to a total of 6 points of 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30. A straight line is drawn from the obtained measurement data by the least square method, and Vm is calculated from the slope and intercept of the straight line. Further, using the value of Vm, the BET specific surface area of the magnetic iron oxide particles is calculated as described above.

<Measurement of magnetic properties of magnetic iron oxide particles>
Using a vibrating sample magnetometer VSM-P7 manufactured by Toei Industry Co., Ltd., measurement was performed at a sample temperature of 25 ° C. and an external magnetic field of 795.8 kA / m.

<Measurement of viscoelasticity of toner>
The storage elastic modulus (G′40) at a temperature of 40 ° C. and the storage elastic modulus (G′70) at a temperature of 70 ° C. are measured as follows.
As a measuring apparatus, a rotating plate type rheometer “ARES” (manufactured by TA INSTRUMENTS) is used.
As a measurement sample, a sample obtained by press molding a toner into a disk shape having a diameter of 7.9 mm and a thickness of 2.0 ± 0.3 mm using a tablet molding machine in an environment of 25 ° C. is used.
The sample is mounted on a parallel plate, heated from room temperature (25 ° C.) to 100 ° C. over 15 minutes to adjust the shape of the sample, then cooled to the measurement start temperature of viscoelasticity, and measurement is started. At this time, the sample is set so that the initial normal force becomes zero. Further, as described below, in the subsequent measurement, the effect of normal force can be canceled by performing automatic tension adjustment (Auto Tension Adjustment ON).
The measurement is performed under the following conditions.
(1) A parallel plate having a diameter of 7.9 mm is used.
(2) The frequency (Frequency) is 6.28 rad / sec (1.0 Hz). (3) The applied strain initial value (Strain) is set to 0.1%.
(4) A temperature between 30 and 200 ° C. is measured at a ramp rate of 2.0 ° C./min. In the measurement, the following automatic adjustment mode setting conditions are used. Measurement is performed in an automatic strain adjustment mode (Auto Strain).
(5) The maximum applied strain (Max Applied Strain) is set to 20.0%.
(6) The maximum torque (Max Allowed Torque) is set to 200.0 g · cm, and the minimum torque (Min Allowed Torque) is set to 0.2 g · cm.
(7) Set the distortion adjustment as 20.0% of Current Strain. In the measurement, an automatic tension adjustment mode (Auto Tension) is adopted.
(8) Set automatic tension direction (Auto Tension Direction) as compression (Compression).
(9) An initial static force (Initial Static Force) is set to 10.0 g, and an automatic tension sensitivity (Auto Tension Sensitivity) is set to 40.0 g.
(10) The operating condition of the automatic tension is that the sample modulus is 1.0 × 10 ³ (Pa) or more.

<Evaluation of toner blackness>
To evaluate the blackness of the toner, the L value in CIE Lab measurement of a solid black image was measured.
Measurement can be performed using Spectrolino manufactured by GretagMacbeth. Specific measurement conditions are shown below.
(Measurement condition)
Observation light source: D50
Observation field: 2 °
Concentration: DIN
White standard: Abs
Filter: No

Although the basic configuration and features of the present invention have been described above, the present invention will be specifically described based on examples. However, the present invention is not limited to these. Note that “parts” and “%” in the following formulations are based on mass unless otherwise specified.

<Example of production of binder resin (A-1)>
[Acid component]
-100 mol parts of terephthalic acid (TPA) [alcohol component]
-Ethylene glycol (EG) 65 mol part-Neopentyl glycol (NPG) 40 mol part The monomer for comprising the said polyester was prepared to the 5L autoclave with the esterification catalyst (dibutyltin oxide). A reflux condenser, a water separator, an N ₂ gas introduction tube, a thermometer, and a stirring device were attached thereto, and a polycondensation reaction was performed at 230 ° C. while introducing N ₂ gas into the autoclave. The progress of the reaction was monitored while monitoring the viscosity, and when the reaction approached late, trimellitic anhydride: 5 mol parts was added. After completion of the reaction, the reaction product was taken out from the container, cooled and pulverized to obtain a binder resin (A-1). Various physical properties of the binder resin are as shown in Table 2 (indicated as “Resin A-1” in the table).

<Examples of production of binder resins (A-2) to (A-11)>
The monomers shown in Table 1 together with an esterification catalyst (dibutyltin oxide) were charged to a 5L autoclave, reflux condenser, water separator, a N ₂ gas inlet, denoted a thermometer and a stirrer, a N ₂ gas into the autoclave While introducing, a polycondensation reaction was carried out at 230 ° C. At this time, the monomers described in Table 1 as “post-addition” were added in the latter stage of the polycondensation reaction. After completion of the reaction, the reaction mixture was taken out from the container, cooled and pulverized to obtain binder resins (A-2) to (A-11). The various physical properties of these binder resins are as shown in Table 2.

<Example of production of magnetic iron oxide particles (B-1)>
10 L of an aqueous solution containing 0.23 mol / L of Si ⁴⁺ as a water-soluble silicate is added to 50 L of an aqueous solution containing 2.0 mol / L of Fe ²⁺ , and stirred and mixed with 42 L of an aqueous solution containing 5.0 mol / L of NaOH. A ferrous hydroxide slurry was obtained. The pH of the ferrous hydroxide slurry was adjusted to 12, and air was blown at 30 L / min at a temperature of 90 ° C. until the core particles were formed to 50%, and then until the core particles were formed to 75%. 20 L / min of air was blown, then 10 L / min of air was blown until 90% of the core particles were formed, and then 5 L / min of air was blown to complete the oxidation reaction, thereby obtaining a core particle slurry. 120 g of sodium silicate aqueous solution (Si grade 13.4%) and 380 g of aluminum sulfate aqueous solution (Al grade 4.2%) were simultaneously added to the magnetic iron oxide particle slurry of the obtained core particles, and the pH was 5 or more. Thus, a magnetic iron oxide particle slurry having a surface formed with a coating layer containing silicon and aluminum was obtained. The obtained slurry containing magnetic iron oxide particles was filtered, dried and pulverized in a conventional manner to obtain magnetic iron oxide particles (B-1). Table 3 shows the physical property values of the magnetic iron oxide particles (B-1) measured by the measurement method.

<Production example of magnetic iron oxide particles (B-2)>
20 L of an aqueous solution containing 0.192 mol / L of Si ⁴⁺ as a water-soluble silicate was added to 50 L of an aqueous solution containing 2.0 mol / L of Fe ²⁺ and mixed with 42 L of an aqueous solution containing 5.0 mol / L of NaOH. Residual NaOH in the obtained slurry was 2.5 g / L. While maintaining the temperature of the slurry at 85 ° C., the air was passed through 65 L / min to oxidize to obtain core particles. Mixing of the resulting slurry with a first aqueous sulfuric acid solution, an aqueous zinc sulfate solution, and an aqueous sodium silicate solution containing Fe ²⁺ 1.30 mol / L, Zn ²⁺ 0.05 mol / L, and Si ⁴⁺ 0.26 mol / L 4.50 L of an aqueous solution was added, oxidation was performed by aeration of air again while maintaining the pH of the mixed slurry at 8.5 and a temperature of 85 ° C., and the surface was coated with composite iron oxide containing zinc and silicon. The obtained slurry of magnetic iron oxide particles was sheared, and then subjected to conventional filtration and washing, followed by pulverization to obtain magnetic iron oxide particles (B-2). Table 3 shows the physical property values of the magnetic iron oxide particles (B-2) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-3)>
5 L of 0.14 mol / L titanyl sulfate aqueous solution was mixed with 50 L of 2 mol / L ferrous sulfate aqueous solution under the conditions of pH 1 and temperature of 50 ° C., and sufficiently stirred. This titanium salt-containing ferrous sulfate aqueous solution and 43 L of 5 mol / L sodium hydroxide aqueous solution were mixed to obtain a ferrous hydroxide slurry. The pH of this ferrous hydroxide slurry was maintained at 12, and air was blown at 85 ° C. to carry out an oxidation reaction. The obtained slurry containing magnetic iron oxide particles was subjected to conventional filtration, washing, drying and pulverization to obtain magnetic iron oxide particles (B-3). Table 3 shows physical property values of the magnetic iron oxide particles (B-3) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-4)>
In the production example of magnetic iron oxide particles (B-1), the pH of the ferrous hydroxide slurry was changed to 13, and the pulverized magnetic iron oxide particles were put into a sand mill MPUV-2 manufactured by Yodocasting Co., Ltd. The magnetic iron oxide particles (B-4) are the same as the magnetic iron oxide particles (B-1) except that the compacting process is performed for 30 minutes at a line load of 140 kg / cm while adjusting the internal atmosphere temperature to 70 ° C. Got. Table 3 shows the physical property values of the magnetic iron oxide particles (B-4) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-5)>
Production of magnetic iron oxide particles (B-3) In the production example of magnetic iron oxide particles (B-3), except that the ferrous hydroxide slurry was changed to pH 13 and the reaction temperature was 80 ° C. Magnetic iron oxide particles (B-5) were obtained in the same manner as in the examples. Table 3 shows the physical property values of the magnetic iron oxide particles (B-5) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-6)>
In the production example of magnetic iron oxide particles (B-1), except that the amount of sodium silicate aqueous solution (Si grade 13.4%) added was 180 g, the production examples of magnetic iron oxide particles (B-1) Similarly, magnetic iron oxide particles (B-6) were obtained. Table 3 shows physical property values of the magnetic iron oxide particles (B-6) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-7)>
65 L of ferrous sulfate aqueous solution containing Fe ²⁺ 1.55 mol / L and 88 L of 2.37 mol / L sodium hydroxide aqueous solution were mixed and stirred. After adjusting so that the residual sodium hydroxide in the mixed aqueous solution is 2.1 g / L, 30 L / min of air is blown while maintaining the temperature at 80 ° C. and the pH at 6 to 8, and the first oxidation reaction is temporarily performed. Ended.
Next, 2.25 L of an aqueous solution containing zinc sulfate added to Zn ²⁺ 0.5 mol / L in a ferrous sulfate aqueous solution containing Fe ²⁺ 1.27 mol / L is prepared separately and added to the reaction slurry described above. While maintaining the pH at 6-8, air of 15 L / min was blown again to complete the second oxidation reaction.
Next, 2.3 L of an aqueous solution in which sodium silicate (No. 3) is added so as to be Si ⁴⁺ 0.44 mol / L in a sulfuric acid first aqueous solution containing Fe ²⁺ 1.01 mol / L is prepared separately. In addition to the reaction slurry, 15 L / min of air was blown again while maintaining the pH at 6 to 8 to complete the third oxidation reaction. The resulting product particles were processed by ordinary washing, filtration, drying, and pulverization processes to obtain magnetic iron oxide particles (B-7). Table 3 shows physical property values of the magnetic iron oxide particles (B-7) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-8)>
50 L of 1.8 mol / L ferrous sulfate aqueous solution, 45 L of caustic soda aqueous solution with a concentration of 3.8 mol / L, and 5 L of sodium silicate 3 of 0.3 mol / L in terms of Si were mixed, and ferrous hydroxide A slurry containing was obtained. While maintaining this slurry at 85 ° C. and pH 6-8, air was blown at a rate of 20 L / min to carry out an oxidation reaction (first stage reaction).
Here, once the air blowing was stopped, 1.9 L of a 1.8 mol / L ferrous sulfate aqueous solution and 1 L of a 0.7 mol / L zinc sulfate aqueous solution were added to the reaction slurry, resulting in a pH of 8. Thus, an appropriate amount of 10 mol / L aqueous caustic soda solution was added. After sufficiently stirring, the oxidation reaction in which air was blown at a rate of 20 L / min was resumed. And it adjusted so that the pH of the reaction slurry in oxidation reaction might be 8-9, and reaction was complete | finished (2nd stage reaction).
The slurry containing the magnetic iron oxide particles obtained in this way was filtered, dried, and crushed in the usual manner, and then put into a sand mill MPUV-2 manufactured by Yodocasting Co., while adjusting the atmospheric temperature in the apparatus to 70 ° C., a line load of 140 kg. Consolidation treatment was performed at / cm for 30 minutes to obtain magnetic iron oxide particles (B-8). Table 3 shows physical property values of the magnetic iron oxide particles (B-8) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-9)>
In a reaction vessel containing 20 L of 3.0 mol / L sodium hydroxide aqueous solution, 20 L of ferrous sulfate aqueous solution with Fe ²⁺ of 1.5 mol / L is added, and the temperature is set to 95 ° C. A ferrous salt suspension containing a colloid was produced.
To this, 0.2 L of an aqueous sodium silicate solution having 28 g of silicon was dropped over 60 minutes while 100 L of air was aerated. Thereafter, the mixture was stirred for 30 minutes to obtain a ferrous suspension containing magnetic iron oxide particles.
A 6.0 mol / L aqueous sodium hydroxide solution was added thereto to adjust the pH to 10.5. Further, 0.1 L of a sodium silicate aqueous solution having 28 g of silicon content was dropped over 30 minutes while 100 L of air was vented, and then stirred for 30 minutes to generate magnetic iron oxide particles.
After adding 150 ml of 0.5 mol / L aluminum sulfate aqueous solution and stirring sufficiently, magnetic iron oxide particles were separated by filtration. This was washed with water, dried and crushed, and then put into a sand mill MPUV-2 manufactured by Yodocasting. While adjusting the atmospheric temperature in the apparatus to 70 ° C., a compaction treatment was carried out for 30 minutes at a line load of 140 kg / cm. Particles (B-9) were obtained. Table 3 shows the physical property values of the magnetic iron oxide particles (B-9) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-10)>
65 L of ferrous sulfate aqueous solution containing Fe ²⁺ 1.54 mol / L and 88 L of 2.38 mol / L sodium hydroxide aqueous solution were mixed and stirred. After adjusting the residual sodium hydroxide in the mixed aqueous solution to 2.1 g / L, 30 L / min of air was blown while maintaining the temperature at 80 ° C., and the first oxidation reaction was once terminated.
Next, 2.25 L of an aqueous solution containing zinc sulfate added to Zn ²⁺ 0.5 mol / L in a ferrous sulfate aqueous solution containing Fe ²⁺ 1.27 mol / L is prepared separately and added to the reaction slurry described above. Then, 15 L / min of air was blown again to complete the second oxidation reaction.
Next, 2.3 L of an aqueous solution in which sodium silicate (No. 3) is added so as to be Si ⁴⁺ 0.60 mol / L in a sulfuric acid first aqueous solution containing Fe ²⁺ 1.01 mol / L is prepared separately. In addition to the reaction slurry, 15 L / min of air was blown again to complete the third oxidation reaction. The resulting product particles were processed by ordinary washing, filtration, drying and crushing steps to obtain magnetic iron oxide particles (B-10). Table 3 shows physical property values of the magnetic iron oxide particles (B-10) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-11)>
18.8 L of 1.6N ferrous sulfate aqueous solution was added to 31.2 L of 1.83 mol / L NaOH aqueous solution containing 2770 g of sodium silicate (No. 3) (SiO ₂ 29 wt%) Fe (
An aqueous ferrous sulfate solution containing OH) ₂ was obtained. At this time, the amount 2OH / Fe of alkali added to iron was 0.95, and the concentration of Fe ²⁺ (including Fe (OH) ₂ ) was 0.6 mol / L. The aqueous ferrous sulfate solution containing Fe (OH) ₂ was bubbled with 100 L of air at a temperature of 90 ° C. for 120 minutes to produce an aqueous solution containing magnetic iron oxide particles.
Subsequently, 1.58 L of a 6N NaOH aqueous solution (corresponding to 1.10 equivalent to Fe ²⁺ ), pH 11.9, temperature 90 ° C., 100 L / min of air was passed through for 60 minutes to produce magnetic iron oxide particles. Reaction was performed. In this alkaline suspension containing magnetic iron oxide particles, 1.56 L of 10% aqueous solution of aluminum sulfate (corresponding to 0.1 wt% with respect to magnetic iron oxide) was added and stirred for 30 minutes, and then 3N diluted sulfuric acid was added. The pH was adjusted to 7 by adding. The obtained black precipitate was filtered, washed with water, dried and crushed by a conventional method. Thereafter, it was put into a sand mill MPUV-2 manufactured by Yodo Casting Co., Ltd., and the compaction treatment was performed for 50 minutes at a linear load of 150 kg / cm while adjusting the atmospheric temperature in the apparatus to 70 ° C. to obtain magnetic iron oxide particles (B-11). It was. Table 3 shows physical property values of the magnetic iron oxide particles (B-11) measured by the measurement method.

<Example of production of magnetic iron oxide particles (B-12)>
65 L of ferrous sulfate aqueous solution containing Fe ²⁺ 1.54 mol / L and 88 L of 2.38 mol / L sodium hydroxide aqueous solution were mixed and stirred. After adjusting the residual sodium hydroxide in the mixed aqueous solution to 2.1 g / L, 30 L / min of air was blown while maintaining the temperature at 80 ° C., and the first oxidation reaction was once terminated.
Next, 2.25 L of an aqueous solution containing zinc sulfate added to Zn ²⁺ 0.5 mol / L in a ferrous sulfate aqueous solution containing Fe ²⁺ 1.27 mol / L is prepared separately and added to the reaction slurry described above. Then, 15 L / min of air was blown again to complete the second oxidation reaction. The resulting product particles were processed by ordinary washing, filtration, drying and crushing steps to obtain magnetic iron oxide particles (B-12). Table 3 shows physical property values of the magnetic iron oxide particles (B-12) measured by the measurement method.

[Example 1]
Binder resin (A-1) 100 parts by mass Magnetic iron oxide particles (B-1) 70 parts by mass Charge control agent-1 shown below 2 parts by mass

After the above materials were premixed with a Henschel mixer, the temperature was set and melt kneaded using a twin-screw kneading extruder shown in FIG.
The obtained kneaded product is cooled, coarsely pulverized with a hammer mill, then pulverized with a jet mill, and the resulting finely pulverized powder is classified using a multi-division classifier utilizing the Coanda effect to obtain a weight average particle size ( D4) 5.5 μm negatively chargeable magnetic toner particles were obtained. Hydrophobic silica fine powder 1 [100 parts by mass of silica fine powder having a BET specific surface area of 150 m ² / g with 30 parts by mass of hexamethyldisilazane (HMDS) and 10 parts by mass of dimethyl silicon oil with respect to 100 parts by mass of magnetic toner particles Hydrophobized one] and 1.0 part by mass of strontium titanate fine powder (particle size [D50]: 1.0 μm at which cumulative volume frequency of particle size distribution is 50%) are externally added and mixed. The toner (C-1) was obtained by sieving with a mesh having an opening of 150 μm. Table 4 shows the toner formulation and the physical properties obtained.
About the obtained toner (C-1), using a commercially available digital copying machine iR5075N (manufactured by Canon Inc.), a high temperature and high humidity environment [HH] (30 ° C., 80% RH), a normal temperature and normal humidity environment [NN ] (23 ° C., 50% RH) Using a test chart with a printing ratio of 5%, 100,000 sheets were continuously printed, and the following evaluation was performed. The results are shown in Table 4.
<Evaluation of drum filming [HH] and [NN]>
For filming on the electrostatic image carrier (photoreceptor drum), 5 halftone images are output continuously in each test environment ([HH], [NN]) after the printing of 100,000 sheets is completed. Then, by visually observing the state of image defects such as white spots and image streaks, the following criteria were used.
A (very good): no image defects B (good): very few image defects C (normal): some image defects D (bad): there are many image defects <fogging [HH] and Evaluation of [NN]>
The fog is measured using a reflectometer (reflectometer model TC-6DS manufactured by Tokyo Denshoku Co., Ltd.). The worst white background reflection density after image formation is Ds, and the average reflection density of the transfer material before image formation is calculated. The fog was evaluated using Dr as the amount of fog and Dr-Ds as the fog amount. Therefore, the smaller the value, the better the fog suppression. This evaluation was performed after 100,000 sheets were printed in each test environment ([HH], [NN]) and evaluated according to the following criteria.
A (very good): fog is less than 1 B (good): fog is 1 or more and less than 3 C (normal): fog is 3 or more and less than 5.
D (bad): fog is 5 or more.
<Color tone measurement (L value [NN])>
For the color tone measurement, a solid black image having a toner transmission density of 1.30 to 1.50 after subtracting paper after printing 100,000 sheets in a normal temperature and humidity environment (23 ° C., 50% RH) is used. The L value in CIE Lab measurement of this solid black image was measured. The smaller the value, the stronger the blackness. The measurement was performed using Spectrolino manufactured by GretagMacbeth.
As for Example 1, good results were obtained in any evaluation.

[Examples 2 to 15]
Toners (C-2) to (C-15) were produced in the same manner as in Example 1, except that the toner production example described in Example 1 was changed to the formulation shown in Table 4. These toners were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.
Regarding Example 2, since the first endothermic peak P1 temperature of the binder resin is near the lower limit of the specified value in the present invention, the drum filming evaluation is C rank in a high temperature and high humidity environment, and B rank in a normal temperature and normal humidity environment. It became.
Regarding Example 3, since the first endothermic peak P1 temperature of the binder resin is near the upper limit of the specified value in the present invention, the drum filming evaluation is C rank in a high temperature and high humidity environment, and B rank in a normal temperature and normal humidity environment. It became. Further, since the heat absorption amounts ΔH1 and ΔH2 of the binder resin are the same, the value of the L value increased. Further, since the BET specific surface area of the magnetic iron oxide particles is outside the above preferable range, the fog evaluation in a high temperature and high humidity environment is ranked B.
Regarding Example 4, since the second endothermic peak P2 temperature of the binder resin is near the lower limit of the specified value in the present invention, the drum filming evaluation is C rank in a high temperature and high humidity environment, and B in a normal temperature and normal humidity environment.
Rank.
Regarding Example 5, since the first endothermic peak P1 temperature of the binder resin is near the upper limit of the above preferable range and the second endothermic peak P2 temperature is near the upper limit of the above preferable range, Environmental evaluation became B rank.
Regarding Example 6, since the second endothermic peak P2 temperature of the binder resin is near the upper limit of the specified value in the present invention, the drum filming evaluation is C rank in a high temperature and high humidity environment, and B rank in a normal temperature and normal humidity environment. It became.
Regarding Example 7, because the oil absorption amount of the magnetic iron oxide particles was the lower limit of the above preferable range, the drum filming evaluation was ranked B in a high temperature and high humidity environment. In addition, since the BET specific surface area of the magnetic iron oxide particles is near the lower limit of the above preferred range, the fog evaluation was B rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment.
Regarding Example 8, since the oil absorption amount of the magnetic iron oxide particles was outside the above-mentioned preferable range, the drum filming evaluation was B rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment. Further, since the BET specific surface area of the magnetic iron oxide particles is near the lower limit of the more preferable range, the evaluation of the fog was B rank in the high temperature and high humidity environment.
Regarding Example 9, since the oil absorption amount of the magnetic iron oxide particles was the upper limit of the above preferable range, the drum filming evaluation was ranked B in a high temperature and high humidity environment. Further, since the BET specific surface area of the magnetic iron oxide particles is near the upper limit of the above preferable range, the evaluation of the fog was B rank in the high temperature and high humidity environment.
Regarding Example 10, since the oil absorption amount of the magnetic iron oxide particles was outside the above-mentioned preferable range, the drum filming evaluation was B rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment. Further, since the BET specific surface area of the magnetic iron oxide particles is outside the above-mentioned preferable range, the evaluation of the fog was C rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment.
Regarding Example 11, since the oil absorption amount of the magnetic iron oxide particles was outside the above preferred range, the drum filming was evaluated as B rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment. In addition, since the BET specific surface area of the magnetic iron oxide particles is near the upper limit of the above preferred range, the fog evaluation was B rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment.
Regarding Example 12, since the oil absorption of the magnetic iron oxide particles is the lower limit of the specified value in the present invention, the drum filming evaluation is C rank in a high temperature and high humidity environment, and B rank in a normal temperature and normal humidity environment. It was. Further, since the BET specific surface area of the magnetic iron oxide particles is outside the above-mentioned preferable range, the evaluation of the fog was C rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment.
Regarding Example 13, since the oil absorption of the magnetic iron oxide particles is the upper limit of the specified value in the present invention, the drum filming evaluation is C rank in a high temperature and high humidity environment and B rank in a normal temperature and normal humidity environment. It was. Further, since the BET specific surface area of the magnetic iron oxide particles is outside the above-mentioned preferable range, the evaluation of the fog was C rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment.
Regarding Example 14, since the first endothermic peak P1 temperature of the binder resin is near the upper limit of the specified value in the present invention, and the oil absorption amount of the magnetic iron oxide particles is the lower limit of the specified value in the present invention, Evaluation of Ming was C rank in both high temperature and high humidity environment and normal temperature and normal humidity environment. Further, since the BET specific surface area of the magnetic iron oxide particles is outside the above-mentioned preferable range, the evaluation of the fog was C rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment.
Regarding Example 15, since the second endothermic peak P2 temperature of the binder resin is near the lower limit of the specified value in the present invention, and the oil absorption amount of the magnetic iron oxide particles is the upper limit of the specified value in the present invention, Evaluation of Ming was C rank in both high temperature and high humidity environment and normal temperature and normal humidity environment. Further, since the BET specific surface area of the magnetic iron oxide particles is outside the above-mentioned preferable range, the evaluation of the fog was C rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment.

[Comparative Example 1-8]
Toners (C-16) to (C-23) were prepared in the same manner as in Example 1 with the formulation shown in Table 5. These toners were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 5.
Regarding Comparative Example 1, since the oil absorption of the magnetic iron oxide particles is outside the range of the specified value in the present invention, the drum filming evaluation is D rank in a high temperature and high humidity environment, and C rank in a normal temperature and normal humidity environment. It was.
Regarding Comparative Example 2, since the oil absorption of the magnetic iron oxide particles is outside the range of the specified value in the present invention, the drum filming evaluation is D rank in a high temperature and high humidity environment, and C rank in a normal temperature and normal humidity environment. It was. Further, since the BET specific surface area of the magnetic iron oxide particles is outside the above-mentioned preferable range, the evaluation of the fog was C rank in both the high temperature and high humidity environment and the normal temperature and normal humidity environment.
Regarding Comparative Example 3, since the first endothermic peak P1 temperature of the binder resin is outside the range of the specified value in the present invention, the drum filming evaluation is D rank in a high temperature and high humidity environment, and a normal temperature and normal humidity environment. It became C rank.
Regarding Comparative Example 4, since the first endothermic peak P1 temperature of the binder resin is outside the range of the specified value in the present invention, the drum filming is evaluated in D rank in a high temperature and high humidity environment and in a normal temperature and normal humidity environment. Rank C.
Regarding Comparative Example 5, since there is no first endothermic peak P1 of the binder resin and the second endothermic peak temperature is outside the range of the specified value in the present invention, the evaluation of drum filming is performed at high temperature and high humidity. D rank in the environment and C rank in the normal temperature and humidity environment.
Regarding Comparative Example 6, since the second endothermic peak P2 temperature of the binder resin is outside the range of the specified value in the present invention, the drum filming is evaluated in D rank in a high temperature and high humidity environment and in a normal temperature and normal humidity environment. Rank C.
Regarding Comparative Example 7, since there was no endothermic peak in the binder resin, the drum filming evaluation was D rank in a high temperature and high humidity environment and C rank in a normal temperature and normal humidity environment.
Regarding Comparative Example 8, since there is no endothermic peak in the binder resin and the oil absorption amount of the magnetic iron oxide particles is outside the range of the specified value in the present invention, the drum filming evaluation is performed in a high temperature and high humidity environment. Both the room temperature and humidity environment were ranked D.

1. 1. heating cylinder, Paddle, 3. Vent hole, 4. 4. Raw material supply port Product outlet, 6. Raw material hopper

Claims (3)

A toner having toner particles containing at least a binder resin and magnetic iron oxide particles as a colorant,
The binder resin has a first endothermic peak at a temperature of 55 ° C. to 75 ° C. and a second endothermic peak at a temperature of 80 ° C. to 120 ° C. in a DSC curve measured by a differential scanning calorimeter. And
The toner according to claim 1, wherein the magnetic iron oxide particles have an oil absorption of 15 ml / 100 g or more and 40 ml / 100 g or less.   When the endothermic amount of the first endothermic peak in the DSC curve measured by the differential scanning calorimeter is ΔH1, and the endothermic amount of the second endothermic peak in the DSC curve measured by the differential scanning calorimeter is ΔH2. The toner according to claim 1, wherein ΔH1 and ΔH2 satisfy a relationship of ΔH1 ≦ ΔH2. The toner according to claim 1, wherein the magnetic iron oxide particles have a BET specific surface area of 7.0 m ² / g or more and 13.0 m ² / g or less.

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