JP7143151B2 - magnetic toner - Google Patents

Description

The present invention relates to a magnetic toner used in electrophotography.

2. Description of the Related Art In recent years, image forming apparatuses such as copiers and printers are required to be more energy efficient as the purposes and environments of use are diversifying. From the viewpoint of improving the energy saving performance of toners, toners with improved low-temperature fixability are first mentioned.
A crystalline material such as wax is used to improve the low-temperature fixability of the toner. The crystalline material melts at its own melting point, plasticizes the binder resin of the toner, and promotes melting deformation of the toner.
However, even with such a toner with improved fixability, there are cases where importance is attached to the performance of tape peeling, in which the toner is partly peeled off by a tape after printing. This is particularly likely to occur in areas such as line images where the amount of toner applied is small, and the reason for this is thought to be insufficient melting characteristics of the toner and insufficient releasability from the fixing member. be done.
In addition to the performance related to fixing as described above, there is a high demand for print image quality, and improvements in developability and transferability are still required.
To solve the above problems, many techniques have been disclosed (for example, see Patent Document 1, Patent Document 2, and Patent Document 3).

JP 2017-40845 JP 2015-118177 JP 2012-68623

However, even the toners proposed in Patent Documents 1 to 3 are inadequate in terms of tape peeling, fixing film contamination, and development and transferability, and improvements are desired.
An object of the present invention is to reduce the size and weight of printers and to reduce the size and weight of a printer. To obtain an image excellent in resistance to

The present invention provides a magnetic toner having toner particles containing a binder resin, wax, and a magnetic material,
The wax contains a hydrocarbon wax and behenyl stearate ,
The magnetic toner has a surface vicinity abundance index of 5 or more and 8 or less, and a standard deviation of the surface vicinity abundance of 0.7 or more and 2.5 or less, obtained by observing the magnetic toner with an SEM. and
70 area % or more and 100 area % or less of the magnetic material within 30% of the distance between the contour and the center point of the cross section from the contour of the cross section in the cross section of the magnetic toner observed with a transmission electron microscope. exist ,
The present invention relates to a magnetic toner characterized by:

According to the present invention, when the process cartridge is miniaturized, which is effective for miniaturizing and reducing the weight of the printer, the magnetic toner has a high level of developability and transferability, and is excellent in resistance to tape peeling. It is possible to obtain an image excellent in

1 is a schematic diagram showing an example of an image forming method and an image forming apparatus using the toner of the present invention; FIG. It is explanatory drawing of the ratio which a magnetic body exists in within 30% of the distance between center points of a cross section and a cross section. FIG. 4 is an explanatory diagram of a system in which a stirring device is incorporated in a circulation path; FIG. 4 is an explanatory diagram of a stirring device in FIG. 3;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail.

The magnetic toner of the present invention contains a binder resin, wax, and a magnetic substance, the wax contains a hydrocarbon wax, and the magnetic toner is a magnetic substance obtained by observing the magnetic toner with an SEM. The near-surface abundance index is 4 or more and 8 or less, and the standard deviation of the near-surface abundance is 0.7 or more and 2.5 or less. Furthermore, in the cross section of the magnetic toner observed with a transmission electron microscope, the magnetic substance is 70 area % or more and 100 areas within 30% of the distance between the contour and the center point of the cross section from the contour of the cross section. % or less.

Here, the tape peeling will be explained based on the study of the present inventors. Tape peeling is a test to see how long the image can withstand without damage when a tape with an adhesive is attached to the image and peeled off at a constant speed. Releasability from adhesives and adhesion to paper are effective. Therefore, a hydrocarbon wax with excellent releasability is an essential material for the present invention.

According to the studies of the present inventors, when the number of magnetic substances in the vicinity of the surface is reduced to a certain extent and the number of magnetic substances in the vicinity of the surface is extremely small due to variations, the fixability, especially the resistance to tape peeling, is dramatically improved. improve. It is believed that this is because the state of dispersion of the magnetic material affects the exudation of the wax component containing the hydrocarbon wax and the wetting and spreading properties of the magnetic toner.

In the magnetic toner of the present invention, the near-surface existence index of the magnetic substance is 4 or more and 8 or less. This near-surface existence index is an index corresponding to the number of magnetic substances that exist unevenly near the surface in the magnetic toner. A high index indicates a large number of magnetic bodies near the surface. If the number of magnetic bodies is large, the wax tends to be hindered from exuding during heat fixing, and the release effect from the adhesive is weakened as described above, resulting in a tendency to deteriorate resistance to tape peeling. Furthermore, since the vicinity of the surface of the magnetic toner is thermally hardened, it is difficult for the magnetic toner to spread by wetting, and the adhesion to paper is also difficult to increase. From the viewpoint of both exudation and spreading of the wax, a lower near-surface existence index is advantageous.

On the other hand, if the number is less than 4, the amount of magnetic material in the vicinity of the surface is small, so when the jumping development method is adopted, for example, the adhesion to the magnetic pole sleeve is reduced, and the developability tends to be deteriorated. . If the number exceeds 8, it is disadvantageous from the viewpoint of wax exudation and wet spreading, and the resistance to tape peeling is greatly deteriorated. In addition, when the number of magnetic bodies in the vicinity of the surface is large, it tends to become a leak point during the development and transfer processes, and the developability and transferability tend to be greatly deteriorated.

The near-surface presence index is preferably 4 or more and 7 or less, more preferably 4 or more and 6 or less.

The dispersion state of the magnetic material in the magnetic toner of the present invention needs to have some degree of variation, and the standard deviation of the abundance near the surface is 0.7 or more and 2.5 or less. If there is this variation, it means that particles with a small number of magnetic substances near the surface are included, and melting or wax exudation occurs starting from these particles during heat fixing. On the other hand, if there is no variation among the particles, the wax exudes and spreads out insufficiently at a temperature below a certain temperature control temperature, and the particles peel off at once. However, due to variations, for example, if particles that are very likely to exude wax are included, a component that dissolves before the whole melts can be included, and the magnetic toner binds from that component as a starting point. Therefore, when the tape is peeled off, a wide area does not peel off, and the tape tends to be excellent in resistance to peeling off. On the other hand, when it is less than 0.7, the variation becomes small, and the resistance to tape peeling tends to deteriorate. If it exceeds 2.5, the resistance to tape peeling will be good, but the dispersion state of the magnetic material will vary, so that the developability and the transferability will tend to deteriorate.

In the toner cross section of the magnetic toner observed with a transmission electron microscope, the toner of the present invention has 70 areas of the magnetic material within 30% of the distance between the contour and the center point of the cross section from the contour of the cross section. % or more and 100 area % or less. This means that the magnetic material is unevenly distributed near the surface. In the magnetic toner of the present invention, it is important that the number of magnetic bodies located near the surface is within an appropriate range and varies to some extent, even though the magnetic bodies are closer to the surface inside the toner, leading to the present invention. .

The toner of the present invention is obtained by unevenly distributing the magnetic bodies near the surface and controlling the number of the magnetic bodies and the variation thereof. Conventional techniques (eg, Patent Documents 1 to 3) cannot satisfy both the near-surface existence index and the degree of variation. According to studies by the present inventors, in order to increase the near-surface existence index, for example, when toner particles are produced in an aqueous medium, it is necessary to apply a large shearing force during granulation in water. On the other hand, in order to control the variation, it is necessary to create a configuration that intentionally produces variation. For example, it is necessary to granulate using multiple devices with significantly different shear forces, or to use multiple types of dispersants. . In the prior art, since the shear force applied during the preparation of toner particles is relatively weak and single compared to the technique used in the present invention, only a single magnetic substance dispersion state can be obtained. It was difficult to control within the range of the present invention even by adjusting.

Preferred embodiments of the toner of the present invention will be described below.

The wax used in the present invention preferably contains an ester wax release agent having a melting point of 60° C. or higher and 72° C. or lower. Since the ester wax described above has excellent plasticizing ability with respect to the binder resin, it is easy to achieve both good tape peeling resistance and toner storage stability.

Next, the total amount of wax contained in the magnetic toner of the present invention is preferably 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin. If the amount of wax is large, the amount of oozing out is large, so the resistance to tape peeling is improved. Because it is easy to develop, there is a tendency for the developability to decrease. When the amount exceeds 40 parts by mass, the developability tends to deteriorate, while when the amount is less than 10 parts by mass, the resistance to tape peeling tends to deteriorate.

The magnetic toner of the present invention preferably satisfies the following physical properties.

(i) In the DSC curve when the temperature of the magnetic toner is lowered from 100°C at a rate of 3°C/min, the maximum exothermic peak Tc observed at 60°C or higher is in the region of Tc-10°C to Tc-5°C. does not have an exothermic peak,
(ii) In the calorific value A [3] in the region of Tc ± 5 ° C. and the calorific value B [3] in the region of Tc - 10 ° C. to Tc - 5 ° C., C [3] represented by formula (1) and , In the DSC curve when the temperature of the magnetic toner is lowered from 180° C. at a temperature of 10° C./min, the heat generation amount A [10] in the region of Tc±5° C. and the heat generation in the region of Tc-10° C. to Tc-5° C. In the quantity B[10], C[10] represented by the formula (2) satisfies the formula (3),
(iii) The calorific value of A[3] is 0.5 J/g or more.
C[3]=B[3]/(A[3]+B[3]) (1)
C[10]=B[10]/(A[10]+B[10]) (2)
C[10]−C[3]>0.21 (3)
([3] in the formula indicates the case where the temperature is lowered at 3°C/min, and [10] indicates the case where the temperature is lowered at 10°C/min.)

The above physical properties will be explained. Consider the image after the fusing process. When the toner that has been plasticized during fixing is allowed to cool, it remains in a softened state that maintains a compatible state with the wax up to a certain temperature. It is controlled to a phase separation state that precipitates in. Maintaining a compatible state improves the wetting and spreadability of the toner on the paper fibers, and when the temperature drops below a certain level, the toner enters a phase-separated state, which rapidly solidifies the toner and firmly attaches to the paper. Stick.

The requirements for obtaining the solidification behavior of the wax during cooling required for the toner of the present invention will be described below.

When the toner is heated to 100° C. and the temperature is slowly lowered at 3° C./min, the wax undergoes phase separation and solidifies as a single substance in a large proportion. At this time, since the wax generates heat as it crystallizes, a crystallization peak (Tc) corresponding to that of the wax alone is obtained in DSC. At this time, the calorific value (A[3]) in the region of Tc±5° C. can be given as a guideline for the content of the wax alone.

On the other hand, when the toner is heated to 100° C. and the temperature is rapidly lowered at 10° C./min, the rate at which the wax solidifies as a single substance decreases, and after maintaining the compatible state up to a certain temperature, the temperature is lower than Tc. More crystals precipitate at higher temperatures. At this time, since there is no time for crystal growth, the precipitated crystals are microcrystals having a size of μm or less. At this time, the calorific value (B[10]) in the region of Tc-10°C to Tc-5°C can be mentioned as a guideline for the content of the microcrystalline wax.

Using this concept, the following C[3] and C[10] can be defined as the susceptibility to generation of microcrystalline wax when the toner is cooled at 3° C./min or 10° C./min. .
C[3]=B[3]/(A[3]+B[3]) (1)
C[10]=B[10]/(A[10]+B[10]) (2)

Note that C[3] and C[10] cannot be defined accurately if there is a peak derived from another material in the region of Tc-10°C to Tc-5°C when the temperature is lowered at 3°C/min. is required.

From these examination results, the present inventors found that the calorific value in the Tc-10 ° C. to Tc-5 ° C. region when cooled quickly; C [10], and the calorific value in the same region when cooled slowly; C [ 3] is considered to indicate the easiness of obtaining a crystallized state in the state of being mixed with wax microcrystals or resin. According to the study results of the present inventors, when C[10]−C[3]>0.21 is satisfied, the wax crystallizes in large amounts while taking not only a single substance but also the above-mentioned crystalline state. , the adhesion to paper tended to be greatly improved.

Also, the size of the crystallization peak of the wax when the temperature is lowered at 3° C./min indicates the amount of wax that can be converted into microcrystalline wax. When this is small, even if the cooling rate is changed, the amount of finely dispersed wax generated is difficult to change. According to the study by the present inventors, it was confirmed that the amount of finely dispersed wax changes favorably when A[3] is 0.5 J/g or more.

Next, the material configuration and manufacturing method that can be used for the toner of the present invention will be described in detail.

First, toner particles and toner that can be used in the present invention will be described in detail.

Toner particles that can be used in the present invention can be produced by any known dry method, emulsion polymerization method, solution/suspension method, suspension polymerization method, and the like. Further, when the image forming method is a cleanerless system, the toner is preferably spherical, the dry method is preferably a surface modification treatment such as thermal spheroidization, and the polymerization method is preferably a suspension polymerization method. Particularly preferably, it is produced by a suspension polymerization method in which a polymerizable monomer composition is granulated in an aqueous medium to form particles of the polymerizable monomer composition.

A particularly preferred suspension polymerization method will be described in detail below.

As the polymerizable monomer, a radically polymerizable vinyl-based monomer is used. A monofunctional monomer or a polyfunctional monomer can be used as the vinyl-based monomer.

Monofunctional monomers include styrene; styrene derivatives such as α-methylstyrene, β-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene; Acrylic polymerizable monomers such as acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, dibutyl phosphate ethyl acrylate, 2-benzoyloxyethyl acrylate; methyl methacrylate, ethyl methacrylate, dibutyl Methacrylic polymerizable monomers such as phosphate ethyl methacrylate; methylene aliphatic monocarboxylic acid esters; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropyl ketone;

Among the above, the polymerizable monomer preferably contains styrene or a styrene derivative.

Polyfunctional monomers include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tetramethylolmethane tetramethacrylate, divinylbenzene, divinyl ether and the like.

The above-described monofunctional monomers may be used singly or in combination of two or more, or the above-described monofunctional monomers and polyfunctional monomers may be used in combination. Polyfunctional monomers can also be used as crosslinkers.

As the polymerization initiator that can be used in the present invention, an oil-soluble initiator and/or a water-soluble initiator are used. Preferably, the half-life at the reaction temperature during the polymerization reaction is 0.5 hours or more and 30 hours or less. Further, when the polymerization reaction is performed in an amount of 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer, a polymer having a maximum molecular weight between 10,000 and 100,000 is usually produced. It is preferable because it can obtain toner particles having suitable strength and fusing properties.

Examples of polymerization initiators include the following 2,2′-azobis-(2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis(cyclohexane-1-carbohydrate nitrile), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo or diazo polymerization initiators such as azobisisobutyronitrile; benzoyl peroxide, t-butylperoxy 2- Ethylhexanoate, t-butyl peroxypivalate, t-butyl peroxyisobutyrate, t-butyl peroxyneodecanoate, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4- Examples include peroxide-based polymerization initiators such as dichlorobenzoyl peroxide and lauroyl peroxide.

In the present invention, in order to control the degree of polymerization of the polymerizable monomer, a known chain transfer agent, polymerization inhibitor, etc. may be further added and used.

In the present invention, the polymerizable monomer composition may contain a polyester resin.

Polyester resins that can be used in the present invention include the following.

Divalent acid components include the following dicarboxylic acids and derivatives thereof. Benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and phthalic anhydride or their anhydrides or their lower alkyl esters; Alkyldicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid or their anhydrides or their lower Alkyl esters; alkenyl succinic acids such as n-dodecenyl succinic acid and n-dodecyl succinic acid or alkyl succinic acids, or anhydrides or lower alkyl esters thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid or its anhydride or its lower alkyl ester.

Examples of dihydric alcohol components include the following. Ethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol (CHDM), hydrogenated bisphenol A, bisphenol and its derivative.

Polyester resins that can be used in the present invention include, in addition to the above-described divalent carboxylic acid compounds and divalent alcohol compounds, monovalent carboxylic acid compounds, monovalent alcohol compounds, trivalent or higher carboxylic acid compounds, 3 An alcohol compound having a higher valence may be contained as a constituent component.

Examples of monovalent carboxylic acid compounds 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 monohydric alcohol compounds 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. be done.

Examples of trivalent or higher carboxylic acid compounds include, but are not limited to, trimellitic acid, trimellitic anhydride, and pyromellitic acid.

Trimethylolpropane, pentaerythritol, glycerin, etc., can be mentioned as trihydric or higher alcohol compounds.

The method for producing the polyester resin that can be used in the present invention is not particularly limited, and known methods can be used.

The crystalline material that can be used in the present invention may be a crystalline polyester resin.

As the alcohol component used as the raw material monomer of the crystalline polyester resin, it is preferable to use an aliphatic diol having 6 or more and 18 or less carbon atoms from the viewpoint of improving the crystallinity. Among these, aliphatic diols having 6 or more and 12 or less carbon atoms are preferable from the viewpoint of fixability and heat resistance stability. Aliphatic diols include 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1, 12-dodecanediol and the like. From the viewpoint of further increasing the crystallinity of the crystalline polyester resin, the content of the aliphatic diol is preferably 80.0 mol % or more and 100.0 mol % or less in the alcohol component.

The alcohol component for obtaining the crystalline polyester resin may contain a polyhydric alcohol component other than the above aliphatic diol. For example, polyoxypropylene adducts of 2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene adducts of 2,2-bis(4-hydroxyphenyl)propane, etc. represented by the above formula (I) aromatic diols such as alkylene oxide adducts of bisphenol A; trihydric or higher alcohols such as glycerin, pentaerythritol and trimethylolpropane.

As the carboxylic acid component used as the raw material monomer of the crystalline polyester resin, it is preferable to use an aliphatic dicarboxylic acid compound having 6 or more and 18 or less carbon atoms. Among these, aliphatic dicarboxylic acid compounds having 6 to 12 carbon atoms are preferable from the viewpoint of toner fixability and heat resistance stability. Examples of aliphatic dicarboxylic acid compounds include 1,8-octanedioic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,11-undecanedioic acid, and 1,12-dodecanedioic acid. be done. The content of the aliphatic dicarboxylic acid compound having 6 to 18 carbon atoms is preferably 80.0 mol % to 100.0 mol % in the carboxylic acid component.

The carboxylic acid component for obtaining the crystalline polyester resin may contain a carboxylic acid component other than the above aliphatic dicarboxylic acid compound. Examples thereof include aromatic dicarboxylic acid compounds and aromatic polyvalent carboxylic acid compounds having a valence of 3 or more, but are not particularly limited thereto. Aromatic dicarboxylic acid compounds also include aromatic dicarboxylic acid derivatives. Specific examples of the aromatic dicarboxylic acid compound preferably include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid, anhydrides of these acids, and alkyl (1 to 3 carbon atoms) esters thereof. . Alkyl groups in the alkyl ester include methyl, ethyl, propyl and isopropyl groups. Trivalent or higher polyvalent carboxylic acid compounds include aromatic carboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid and pyromellitic acid, and these Derivatives such as acid anhydrides and alkyl (having 1 to 3 carbon atoms) esters can be mentioned.

The crystalline polyester preferably has a weight average molecular weight (Mw) of 10,000 to 60,000, more preferably 25,000 to 45,000. This is because the crystalline polyester tends to be phase-separated from the binder resin in the toner manufacturing process, and the developability tends to be excellent.

The weight average molecular weight (Mw) of the crystalline polyester can be controlled by various manufacturing conditions and monomer composition of the crystalline polyester. In particular, when a monoalcohol or monocarboxylic acid is used together as a monomer, the molecular weight tends to decrease. When it is desired to adjust the molecular weight to 50,000 or more, it is preferable not to use a monoalcohol or a monocarboxylic acid together.

Regarding the acid value (mgKOH/g) of the crystalline polyester, it is preferable to keep it low from the viewpoint of enhancing the plasticity of the crystalline polyester. Specifically, it is 8.0 or less. It is more preferably 5.0 or less, still more preferably 4.5 or less.

A crystalline polyester and an amorphous polyester can be used in combination in the toner of the present invention. This is expected to be effective not as a binder resin but as, for example, a shell layer. The amorphous polyester is preferably contained in an amount of 1.0 parts by mass or more, more preferably 1.0 parts by mass or more and 20.0 parts by mass or less based on 100 parts by mass of the binder resin.

The toner of the present invention contains at least hydrocarbon wax. Low-molecular-weight polyethylene, low-molecular-weight polypropylene, microcrystalline wax, and paraffin wax are preferable from the viewpoint of high releasability. Moreover, waxes other than hydrocarbon waxes represented by fatty acid esters may be used in combination.

Specific examples of waxes include the following. Sasol H1, H2, C80, C105, C77 (Schumann Sasol), HNP-1, HNP-3, HNP-9, HNP-10, HNP-11, HNP-12, HNP-51 (Nippon Seiro Co., Ltd.) ).

In the present invention, when a wax containing fatty acid ester as a main component (hereinafter referred to as ester wax) is used in combination as a release agent, the binder resin can be easily plasticized and the low-temperature fixability can be easily improved. Furthermore, in a specific manufacturing method, it is easy to form microdomains and to easily control the shape suitable for the present invention, which is preferable.

In the present invention, it is preferred that the crystalline material contains a monoester compound. A monoester compound means an ester wax in which the number of ester groups contained in one molecule is one.

Examples of fatty alcohols include 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, undecyl alcohol, lauryl alcohol, myristyl alcohol, 1-hexadecanol, stearyl alcohol, arachidyl alcohol. , behenyl alcohol, and lignoceryl alcohol. Examples of aliphatic carboxylic acids include pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid. mentioned.

The number of carbon atoms contained in one molecule of the monoester compound is preferably 36 or more and 42 or less. A monoester compound having 36 or more carbon atoms tends to increase the electrical conductivity of the lamellar structure due to its relatively long alkyl chain. Further, a monoester compound having 42 or less carbon atoms is preferable because the monoester compound can sufficiently plasticize the binder resin when the toner is subjected to heat.

As the monoester wax, a condensate of an aliphatic alcohol having 6 to 24 carbon atoms and a long-chain carboxylic acid, or a condensate of an aliphatic carboxylic acid having 4 to 24 carbon atoms and a long-chain alcohol can be used. Any long-chain carboxylic acid or long-chain alcohol can be used here, but it is necessary to combine monomers that satisfy the melting point of the present invention.

It is preferable that the total carbon number of the monoester wax is 36 or more and 44 or less, because it is easy to achieve both the ability to plasticize the resin and the storage stability.

For the toner of the present invention, a differential scanning calorimeter (DSC) was used to raise the temperature to 180° C. and then lower the temperature. If C is the calorific value in the range of ±5°C, and D is the calorific value in the temperature range lower than the maximum exothermic peak temperature by 5°C or more and 15°C or less, D/C is 0.5 or more and 4.0 or less. preferable.

In the toner of the present invention, fine domains of the crystalline material are present in a cross section of the toner observed with a transmission electron microscope, and the number average length of the fine domains is preferably 50 nm or more and 350 nm or less. Furthermore, it is preferable that 60% or more and 100% or less of the minute domains exist within 25% of the distance between the contour and the center point of the cross section from the contour of the cross section.

In the present invention, the crystalline material preferably contains a hydrocarbon wax from the viewpoint of controllability of the microdomain formation.

Hydrocarbon waxes are known to crystallize in a form in which linear hydrocarbon chain portions are stacked, and examples thereof include paraffin wax and Fischer-Tropsch wax.

In the suspension polymerization method, which is a preferable method for producing the toner in the present invention, the hydrocarbon wax tends to form a large domain near the center of the toner. For this reason, it becomes easier to locally unevenly distribute the microdomains in the vicinity of the surface of the toner, making it easier to control.

The toner of the present invention is a magnetic toner using magnetic powder. The magnetic powder is mainly composed of magnetic iron oxide such as triiron tetroxide and γ-iron oxide, and may contain elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum and silicon. . These magnetic powders preferably have a BET specific surface area of 2 m ² /g or more and 30 m ² /g or less, more preferably 3 m ² /g or more and 28 m ² /g or less, as determined by the nitrogen adsorption method. Moreover, those having a Mohs hardness of 5 or more and 7 or less are preferable. The shape of the magnetic powder includes polyhedrons, octahedrons, hexahedrons, spheres, needles, scales, and the like. It is preferable in terms of enhancement.

The magnetic powder preferably has a number average particle size of 0.10 μm or more and 0.40 μm or less. In general, the smaller the particle size of the magnetic powder, the higher the coloring power, but the magnetic powder tends to aggregate.

The number average particle diameter of the magnetic powder can be measured using a transmission electron microscope. Specifically, the toner particles to be observed are sufficiently dispersed in an epoxy resin, and then cured in an atmosphere at a temperature of 40° C. for 2 days to obtain a cured product. The obtained cured product is treated with a microtome as a flaky sample, and the particle size of 100 magnetic powder particles in the field of view is measured with a transmission electron microscope (TEM) at a magnification of 10,000 to 40,000 times. Then, the number average particle diameter is calculated based on the equivalent diameter of a circle equal to the projected area of the magnetic powder. It is also possible to measure the particle size with an image analyzer.

Magnetic powder used in the toner of the present invention can be produced, for example, by the following method. An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide in an amount equal to or greater than that of the iron component to the ferrous salt aqueous solution. While maintaining the pH of the prepared aqueous solution at pH 7 or higher, air is blown in, and while the aqueous solution is heated to 70° C. or higher, the ferrous hydroxide is oxidized, and the seed crystals that form the core of the magnetic iron oxide powder are first removed. Generate.

Next, an aqueous solution containing about 1 equivalent of ferrous sulfate based on the amount of alkali previously added is added to the slurry containing the seed crystals. While maintaining the pH of the liquid at 5 to 10 and blowing in air, the reaction of ferrous hydroxide is promoted to grow magnetic iron oxide powder with the seed crystal as the core. At this time, it is possible to control the shape and magnetic properties of the magnetic powder by selecting arbitrary pH, reaction temperature, and stirring conditions. Although the pH of the liquid shifts to the acidic side as the oxidation reaction progresses, it is preferable not to make the pH of the liquid less than 5. A magnetic powder can be obtained by filtering, washing and drying the magnetic material thus obtained by a conventional method.

Further, in the present invention, when the toner is produced in an aqueous medium, it is very preferable to subject the surface of the magnetic powder to hydrophobic treatment. In the case of dry surface treatment, the magnetic powder that has been washed, filtered and dried is treated with a coupling agent. In the case of wet surface treatment, after the oxidation reaction is completed, the dried product is redispersed, or after the oxidation reaction is completed, the iron oxide body obtained by washing and filtering is placed in another aqueous medium without drying. re-dispersed to , and subjected to coupling treatment. In the present invention, either the dry method or the wet method can be appropriately selected.

Examples of coupling agents that can be used in the surface treatment of the magnetic powder in the present invention include silane coupling agents and titanium coupling agents. Silane coupling agents are more preferably used, and are represented by general formula (I).
_{Rm SiYn} (I)
[Wherein, R represents an alkoxy group, m represents an integer of 1 or more and 3 or less, Y represents a functional group such as an alkyl group, a vinyl group, an epoxy group, or a (meth)acrylic group, and n represents 1 or more and 3 Indicates the following integers. However, m+n=4. ]

In the present invention, those in which Y in general formula (I) is an alkyl group can be preferably used. Of these, alkyl groups having 3 to 6 carbon atoms are preferred, with 3 or 4 being particularly preferred.

When using the silane coupling agent, it is possible to treat alone or to use a plurality of types in combination. When multiple types are used in combination, each coupling agent may be treated individually or simultaneously.

The total processing amount of the coupling agent used is preferably 0.9 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the magnetic powder. It is important to adjust the amount of treatment agent accordingly.

In the present invention, other coloring agents may be used together with the magnetic powder. Colorants that can be used in combination include the above-described known dyes and pigments, as well as magnetic or non-magnetic inorganic compounds. Specifically, ferromagnetic metal particles such as cobalt and nickel, or alloys obtained by adding chromium, manganese, copper, zinc, aluminum, and rare earth elements to these. Particles such as hematite, titanium black, nigrosine dyes/pigments, carbon black, phthalocyanines, and the like. These are also preferably used after surface treatment.

The magnetic powder content in the toner can be measured using a thermal analyzer TGA7 manufactured by PerkinElmer. The measuring method is as follows. The toner is heated from room temperature to 900° C. at a heating rate of 25° C./min in a nitrogen atmosphere. The weight reduction mass % between 100° C. and 750° C. is taken as the binder resin amount, and the residual mass is approximately taken as the magnetic powder amount.

In the method of producing toner particles by the suspension polymerization method, in addition to the materials described above, known charge control agents, conductivity-imparting agents, lubricants, abrasives, and the like may be added.

The method for producing toner particles by suspension polymerization includes a dissolving step of uniformly dissolving or dispersing these additives to form a polymerizable monomer composition, a dissolving step of dissolving the polymerizable monomer composition, and adding a dispersion stabilizer. A granulation step of dispersing and granulating in the containing aqueous medium using a suitable stirrer, and if necessary, a polymerization reaction step of adding an aromatic solvent and a polymerization initiator to carry out a polymerization reaction, crystallinity Toner particles having a desired particle size are obtained through a cooling process for controlling the location and size of minute domains of the material, and a holding (annealing) process for controlling the degree of crystallinity of the crystalline material.

A method for producing toner particles that can be used in the present invention includes adding 0.1% by mass or more and 1.0% by mass or less of magnesium chloride to an aqueous medium containing a dispersion stabilizer, based on the polymerizable monomer composition. is preferable for controlling the near-surface existence index of the magnetic material. In addition, by containing a predetermined amount of magnesium chloride in the aqueous medium, it is possible to suppress the monomer of the polymerizable monomer from dissolving into the aqueous medium from the particles of the polymerizable monomer composition due to its salting-out effect. . If the polymerizable monomer dissolves in the aqueous medium, the dispersion stabilizer adheres to the monomer, resulting in formation of fine particles such as so-called emulsified particles. Moreover, starting from the emulsified particles, the particles of the polymerizable monomer composition having a desired particle size may be adhered to each other to form coalesced particles.

In the magnetic toner of the present invention, it is preferable to add the above-described magnesium chloride as means for imparting dispersion to the magnetic material. The dispersant is mainly composed of hydroxyapatite, but it also contains a mixture in which calcium in the apatite is replaced with magnesium. Therefore, it becomes a system containing multiple kinds of dispersants, and it is easy to intentionally create and control variations.

Further, in the present invention, it has a step of mixing the polymerizable monomer composition obtained in the granulation step and a second aqueous medium, the second aqueous medium is based on the first dispersion stabilizer A It is preferable to contain the second dispersion stabilizer B in an amount of 5.0% by mass or more and 60% by mass or less.

The dispersion stabilizer A is preferably prepared by mixing an aqueous calcium chloride solution and an aqueous sodium phosphate solution.

FIG. 3(a) shows a system in which the agitator having high shear force is incorporated in the circulation path, and FIG. 3(b) shows a side view of the main body of the agitator. However, the stirring device used in the present invention is not limited to this. 4(a) and 4(b) are cross-sectional views of the main body of the agitator, respectively, taken along AA' cross-section in FIG. 3(a) and BB' cross-section in FIG. 3(b). It is a diagram. Moreover, FIG.4(c) and FIG.4(d) respectively show the perspective view of the rotor of a stirring apparatus, and the perspective view of a stator. The stirring device will be specifically described below.

In FIG. 3(a), a polymerizable monomer and at least a magnetic material are put into a holding tank A8 to obtain a prepared solution. The charged prepared liquid is supplied from the inlet of the mixing device through the circulation pump A10, passes through the slits of the rotor A25 and the stator A22 provided inside the casing A2 in the agitation device, and flows in the centrifugal direction. discharged to When the prepared liquid passes through the agitator, the prepared liquid is mixed and dispersed due to the centrifugal compression caused by the displacement of the slits of the rotor and stator, the impact due to discharge, and the impact due to shearing between the rotor and stator. , to obtain a magnetic substance-containing polymerizable monomer (magnetic substance dispersion step). Further, a release agent and a crystalline polyester are added to the magnetic substance-containing polymerizable monomer in the holding tank A8, and similarly circulated between the stirring device and the holding tank A8 to mix and disperse, and the polymerizable monomer is mixed and dispersed. A polymer composition is obtained (polymerizable monomer composition preparation step).

The shape of the rotor and stator is such that ring-shaped protrusions having a plurality of slits are formed in multiple stages on concentric circles, and the rotor and stator are kept at regular intervals and mesh with each other. It is preferably installed coaxially with the Since the rotor and the stator are installed so as to mesh with each other, the short path is reduced and the prepared liquid can be sufficiently dispersed. In addition, since the rotors and stators alternately exist in multiple stages in the concentric direction, the prepared liquid receives a lot of shear and impact when it advances in the centrifugal direction, so the dispersion level can be further increased. Since the holding tank A8 has a jacket structure, it is possible to cool and heat the processed material.

The peripheral speed of the rotor and stator is the peripheral speed of the maximum diameter of the rotor and stator. In the present invention, if the peripheral speed of the rotor A25 is G (m/s), it is preferable to rotate the rotor A25 at 20≤G≤60 to stir the prepared liquid. More preferably, the peripheral speed G of the rotor is 30≦G≦40. If the peripheral speed G of the rotor is 20 ≤ G ≤ 60, the centrifugal compression of the prepared liquid caused by the displacement of the slits of the rotor and stator, the impact due to discharge, and the impact due to shear between the rotor and stator. increases and a high degree of dispersion is achieved. As a result, dispersion unevenness of the prepared liquid is much less than before, and a uniform dispersion state can be achieved. A specific example of the stirring device described above is Cavitron (manufactured by Eurotech).

In addition to the stirring device described above, a stirring device having a stirring blade having a high shearing force, which is generally used for emulsification and dispersion, may be used. Specific examples of stirring blades having a high shear force include CLEARMIX dissolver (manufactured by M-Technic Co., Ltd.) and Disper (manufactured by Tajima Chemical Kikai Co., Ltd.).

In particular, in order to control the near-surface index of the present invention, it is preferable to dispose the Cavitron in the above-described circulatory system and to perform stirring with CLEARMIX at the same time. By promoting the dispersion of the magnetic material with Cavitron, which can impart a strong shearing force, and adding CLEARMIX, which has a relatively weak shearing force, it is possible to create a system that easily produces moderate variations.

After completion of polymerization, the toner particles obtained as described above are subjected to filtration, washing, and drying by a known method. can be obtained.

As the inorganic fine powder, known ones can be used. Preferred are silica fine particles such as titania fine particles, wet-process silica and dry-process silica, and inorganic fine powder obtained by surface-treating these silica with a silane coupling agent, a titanium coupling agent, silicone oil, or the like. The surface-treated inorganic fine powder preferably has a hydrophobicity of 30 or more and 98 or less as determined by a methanol titration test.

Next, an image forming apparatus using an image forming method that can be used in the present invention will be described in detail.

FIG. 1 is a schematic diagram showing an example of an image forming apparatus using an image forming method that can be used in the present invention.

The electrostatic latent image carrier 100 is charged by a roller-shaped charging member (charging roller) 117 and exposed by being irradiated with a laser beam 123 by a laser generator 121 . An electrostatic latent image corresponding to the desired image is formed on the surface. The electrostatic latent image carrier 100 and the toner carrier 102 rotate in the directions of the arrows. Toner is stored in the developing device 140 and supplied to the toner carrier 102 by the toner stirring member 141 . The supplied toner is regulated at the nip portion between toner carrier 102 and toner regulating member 142, conveyed to a development area where electrostatic latent image carrier 100 and toner carrier 102 face each other, and developed. The developed toner image is conveyed to the transfer area where the electrostatic latent image carrier 100 and the transfer member 114 face each other, transferred to the transfer material P, and heat-fixed by the fixing device 126 . Further, the toner remaining on the electrostatic latent image carrier 100 without being transferred is conveyed to the cleaning area where the electrostatic latent image carrier 100 and the cleaning member 116 face each other, and is scraped off by a cleaning blade or the like.

In the charging process, the electrostatic latent image carrier 100 and the charging roller 117 are brought into contact with each other by forming an abutment portion, and a predetermined charging bias is applied to the charging roller 117 to charge the surface of the electrostatic latent image carrier 100 to a predetermined level. It is preferable to use a contact charging method in which the film is charged to the polarity and potential of . By performing contact charging in this manner, stable and uniform charging can be performed, and further, the generation of ozone and the like can be reduced. Further, it is more preferable to use a charging roller 117 that rotates in the same direction as the electrostatic latent image carrier 100 in order to maintain uniform contact with the electrostatic latent image carrier 100 and perform uniform charging.

As preferable process conditions when the charging roller is used, the contact pressure of the charging roller is 4.9 N/m or more and 490.0 N/m or less, and a DC voltage or a DC voltage superimposed with an AC voltage can be exemplified. It is preferable that the AC voltage is 0.5 kVpp or more and 5.0 kVpp or less, the AC frequency is 50 kHz or more and 5 kHz or less, and the DC voltage has an absolute value of 400 V or more and 1,700 V or less. Further, it is preferable that the peripheral speed difference of the charging roller with respect to the electrostatic latent image bearing member is 100% or more and 150% or less.

Materials for the charging roller include the following materials for the elastic layer, but are not limited to these. Ethylene-propylene-diene polyethylene (EPDM), urethane, butadiene acrylonitrile rubber (NBR), silicone rubber, isoprene rubber, etc., in which conductive substances such as carbon black and metal oxides are dispersed to adjust electrical resistance. , and foamed versions of these. It is also possible to adjust the electrical resistance by using an ion-conducting material without dispersing the conductive substance or in combination with the conductive substance.

Further, aluminum, SUS, and the like can be used as the core metal used for the charging roller. The charging roller is placed in contact with a member to be charged, which is an electrostatic latent image carrier, with a predetermined pressing force against elasticity, and is a contact portion between the charging roller and the electrostatic latent image carrier. A charging contact portion is formed.

In the development process, the electrostatic latent image carrier and the toner carrier form an abutting portion and contact each other, and a predetermined developing bias is applied to the toner carrier to develop the electrostatic latent image on the electrostatic latent image carrier. It is preferable to use a contact development system in which the image is a toner image. By performing such contact development, a high-definition toner image can be obtained, and a high-quality output image can be obtained. Further, since contact development is performed, the toner carrier preferably has an elastic layer on the surface of the substrate.

The developing step is preferably a step of applying a developing bias to the toner bearing member to turn the electrostatic latent image on the electrostatic latent image bearing member into a toner image. A voltage on which an alternating electric field is superimposed may be used.

As the waveform of the alternating electric field, a sine wave, rectangular wave, triangular wave, or the like can be appropriately used. Alternatively, it may be a pulse wave formed by periodically turning on/off a DC power supply. As described above, a bias whose voltage value changes periodically can be used as the waveform of the alternating electric field. Further, in the developing process, when magnetic toner is used, it is necessary to arrange a magnet inside the toner carrier. In this case, the toner carrying member preferably has a fixed magnet having multiple poles inside, and preferably has 3 to 10 magnetic poles.

Further, in the developing process, it is preferable that the toner layer thickness on the toner carrier is regulated by bringing the toner regulating member into contact with the toner carrier through the toner. By doing so, high image quality without fog can be obtained. A regulating blade is generally used as the toner regulating member that abuts on the toner carrier, and can be suitably used in the present invention as well.

Rubber elastic bodies such as silicone rubber, urethane rubber, and NBR; synthetic resin elastic bodies such as polyethylene terephthalate; metal elastic bodies such as phosphor bronze plates and SUS plates; It can be. Further, an elastic support such as rubber, synthetic resin, or metal elastic body is coated with a charge control substance such as resin, rubber, metal oxide, or metal so as to come into contact with the toner carrier for the purpose of controlling the chargeability of the toner. You can also use the one attached to . Among these, it is particularly preferable to bond a resin or rubber to a metal elastic body so as to contact the contact portion of the toner carrier.

As the material of the member to be attached to the metal elastic body, it is preferable to use a material that is easily positively charged, such as urethane rubber, urethane resin, polyamide resin, or nylon resin.

The upper side of the regulating blade is fixed to the developing device, and the lower side of the regulating blade is bent in the forward or reverse direction of the toner carrier against the elastic force of the blade. It is brought into contact with the surface with an appropriate elastic pressing force.

The contact pressure between the regulating blade and the toner carrier is preferably 1.30 N/m or more and 245.0 N/m or less, more preferably 4.9 N/m or more and 118.0 N/m, as linear pressure in the toner carrier generatrix direction. The following are more preferred. When the contact pressure is 1.30 N/m or more, uniform application of toner is facilitated, and fogging and scattering are less likely to occur. When the contact pressure is 245.0 N/m or less, a large pressure is not applied to the toner, and deterioration of the toner is not caused.

As the transfer process, a contact transfer method using a transfer member such as a transfer roller is preferable. In the contact transfer method, a toner image is electrostatically transferred onto a recording medium while an electrostatic latent image bearing member is in contact with a transfer member to which a voltage having a polarity opposite to that of the toner is applied through the recording medium. The contact pressure of the transfer member is preferably a linear pressure of 2.9 N/m or more, more preferably 19.6 N/m or more. When the linear pressure as the contact pressure is 2.9 N/m or more, the recording medium is less likely to be conveyed out of alignment or to have poor transfer.

As the cleaning process, a blade cleaning system having a cleaning blade is preferable. The cleaning blade is generally held at the tip of a support made of sheet metal. One end of the cleaning blade in the short direction is fixed to the leading end of the support so that the longitudinal direction of the cleaning blade is substantially parallel to the longitudinal direction of the electrostatic latent image carrier, and the other end in the short direction is fixed to the tip of the support. The free end, which is the portion, is disposed so as to abut against the electrostatic latent image carrier in the counter direction.

As the material of the cleaning blade, a rubber material is suitable from the viewpoint of followability to the surface of the electrostatic latent image carrier and difficulty in scratching the surface of the electrostatic latent image carrier. Among them, polyurethane rubber is the most suitable in terms of physical properties and chemical durability. The rubber material constituting the cleaning blade preferably has a rubber hardness of 60 degrees or more and 90 degrees or less in International Rubber Hardness (IRHD) from the viewpoint of stability in cleaning the toner from the electrostatic latent image carrier.

The cleaning performance is greatly affected by the setting of the contact angle and contact line pressure of the cleaning blade. As for the contacting method of the cleaning blade, the rubber blade is fixed to a support which is inclined by 15° or more and 45° or less with respect to the tangential line of the electrostatic latent image carrier at the contacting position of the cleaning blade, and is brought into contact with the counter. is preferred.

The contact linear pressure of the cleaning blade is preferably set to about 10 N/m or more and 100 N/m or less from the viewpoint of preventing the toner from slipping through. The contact line pressure can be measured by providing a load transducer (load cell) at the portion where the cleaning blade is fixed. As a measuring method, a cleaning device in the main body of the image forming apparatus may be modified to install a load converter, or a HEIDON friction tester manufactured by Shinto Kagaku Co., Ltd. (tribostation TYPE32 modified machine) may be used.

A known fixing method can be used for the fixing process. A halogen heater, an IH heater, or the like is preferably used as a heat source when a heated fixing member is used. The shape of the fixing member may be a roller or an endless belt.

Next, methods for measuring the physical properties of the toner particles, the toner, and the toner carrying member are as follows. Also in the examples described later, the physical properties are measured based on these methods.

<Method for measuring weight average particle size (D4) and number average particle size (D1)>
The weight-average particle diameter (D4) and number-average particle diameter (D1) of the toner were measured by a precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, Beckman Co., Ltd.) by the pore electrical resistance method equipped with a 100 μm aperture tube. (manufactured by Coulter, Inc.) and the attached dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.) for setting measurement conditions and analyzing measurement data. It was measured in the channel, and the measurement data was analyzed and calculated.

As the electrolytic aqueous solution used for measurement, a solution obtained by dissolving special grade sodium chloride in ion-exchanged water to a concentration of about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.) can be used.

Prior to the measurement and analysis, the dedicated software was set as follows.

In the "change standard measurement method (SOM) screen" of the dedicated software, set the total count number in control mode to 50000 particles, set the number of measurements to 1, and set the Kd value to "standard particle 10.0 μm" (Beckman Coulter Co., Ltd. (manufactured) to set the value obtained using By pressing the threshold/noise level measurement button, the threshold and noise level are automatically set. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the flash of aperture tube after measurement.

In the "pulse-to-particle size conversion setting screen" of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range from 2 μm to 60 μm.

A specific measuring method is as follows.
1. About 200 ml of the electrolytic aqueous solution is placed in a 250 ml round-bottomed glass beaker exclusively for Multisizer 3, set on a sample stand, and stirred counterclockwise at 24 rpm with a stirrer rod. Then, use the analysis software's "flush aperture" function to remove dirt and air bubbles inside the aperture tube.
2. About 30 ml of the electrolytic aqueous solution was placed in a 100 ml flat-bottomed glass beaker. About 0.3 ml of a diluted solution obtained by diluting a 10% by mass aqueous solution of a neutral detergent (manufactured by Wako Pure Chemical Industries, Ltd.) with ion-exchanged water by 3 times by mass is added.
3. A predetermined amount of ions was placed in a water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetora 150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two oscillators with an oscillation frequency of 50 kHz built in with a phase shift of 180 degrees. Replaced water is put in, and about 2 ml of the contaminon N is added to this water tank.
4. 2. above. is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker is maximized.
5. 4 above. 10 mg of toner is added little by little to the electrolytic aqueous solution in a beaker and dispersed therein while the electrolytic aqueous solution is irradiated with ultrasonic waves. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. In the ultrasonic dispersion, the temperature of the water in the water tank is appropriately adjusted to 10°C or higher and 40°C or lower.
6. The above 1. installed in the sample stand. The toner was dispersed in the round-bottomed beaker of 5. using a pipette. is added dropwise to adjust the measured concentration to about 5%. Then, the measurement is continued until the number of measured particles reaches 50,000.
7. The measurement data is analyzed by the dedicated software attached to the apparatus, and the weight average particle size (D4) and number average particle size (D1) are calculated. When graph/number% and graph/volume% are set in the dedicated software, the "arithmetic diameter" on the analysis/number statistical value (arithmetic mean) and analysis/volume statistical value (arithmetic mean) screens is the number average. Particle size (D1) and weight average particle size (D4).

<Method for calculating the number average grain size of the long axis of the microdomain of the crystalline material>
The number average diameter of the major axis of the microdomain of the crystalline material means the number average diameter obtained from the major axis of the domain of the crystalline material based on the toner cross-sectional image observed with a transmission electron microscope (TEM). .

A toner cross section observed with a transmission electron microscope (TEM) is prepared as follows.

When the toner is dyed with ruthenium, the crystalline material is not dyed, so the domains of the crystalline material appear black when viewed with a TEM, thus distinguishing the domains. In calculating the domain diameter, cross sections of 100 or more toner particles are observed. All domains are measured and the number average diameter is calculated. The obtained number-average diameter is taken as the number-average diameter of the major axis of the domain of the crystalline substance.

<Method for calculating the ratio of the magnetic material present within 30% of the distance between the contour of the cross section and the center point of the cross section>
As in the method for calculating the number average particle size of the long axis of the microdomain of the crystalline material, the result of observation with a transmission electron microscope is used. As shown in FIG. 2, first, draw a center point in the TEM image, measure the distance to the contour, and draw a circle connected by a length of 70% of the distance. Count the number of magnetic substances present in the area painted in gray in FIG. 2 and calculate the ratio to the total number. The state in FIG. 2 is 70%. Note that the magnetic material on the boundary line is added according to the area within the gray area. For example, if half is in the gray area, count as 0.5.

<Method for Calculating Near-Surface Existence Index>
In the magnetic toner of the present invention, it is important to control the existence index near the surface. The index is the number of magnetic substances present near the surface of the magnetic toner particles, and indicates the number per 1 μm ² of surface area.

The near-surface index is calculated using an image obtained by observing a backscattered electron image of S-4800.

The anti-contamination trap attached to the scope of the S-4800 is flooded with liquid nitrogen and left for 30 minutes. Start the "PC-SEM" of the S-4800 and perform flushing (cleaning of the FE chip, which is the electron source). Click the acceleration voltage display part of the control panel on the screen and press the [Flushing] button to open the flushing execution dialog. Confirm that the flushing intensity is 2 and execute. Confirm that the emission current due to flashing is 20 to 40 μA. Insert the sample holder into the sample chamber of the S-4800 scope. Press [Origin] on the control panel to move the sample holder to the observation position.

Click the acceleration voltage display to open the HV setting dialog, and set the acceleration voltage to [5.0 kV] and the emission current to [20 μA]. In the [Basic] tab of the operation panel, set the signal selection to [SE], select [Upper (U)] and [+BSE] for the SE detector, and select [ L. A. 100] to set the mode for observing backscattered electron images. Similarly, in the [Basic] tab of the operation panel, set the probe current in the electron optical system condition block to [Normal], the focus mode to [UHR], and the WD to [3.0 mm]. Press the [ON] button on the acceleration voltage display section of the control panel to apply the acceleration voltage.

In the magnetic toner of the present invention, the magnetic material is observed to glow white under the observation conditions described above. Focus on the glowing magnetic material and save the SEM image. Using the image analysis software image-J, the number of magnetic bodies is detected as a luminance peak from this image, and the number of magnetic bodies per unit area is calculated. In the present invention, the above analysis was performed on 100 particles, and the average value was taken as the presence index near the surface.

<Method for measuring C[3] and C[10] by DSC>
It is measured according to ASTM D3418-82 using a differential scanning calorimeter "Q2000" (manufactured by TA Instruments). The melting points of indium and zinc are used to correct the temperature of the device detector, and the heat of fusion of indium is used to correct the amount of heat. Specifically, about 2 mg of the sample was precisely weighed, placed in an aluminum pan, and an empty aluminum pan was used as a reference. Measurements are made at 0°C/min. In the measurement, the temperature is once raised to 180° C. and then lowered to 30° C. at a rate of 3.0° C./min. In the DSC curve obtained in this temperature-lowering process, the calorific value in the region of ±5 ° C. with respect to the maximum exothermic peak temperature (Tc) obtained using monoester alone, and the heat generation in the region of Tc-5 ° C. to Tc-10 ° C. Quantity is used to calculate C[3][J/g]. Next, the same operation as described above is performed again, and measurement is performed at a heating rate of 10.0° C./min. C[10] is calculated using the data of temperature programmed toxicity at 10.0° C./min to obtain C[10]−C[3].

<Method for measuring molecular weight of crystalline polyester, etc.>
The molecular weights of the crystalline polyester, amorphous saturated polyester resin and toner are measured by gel permeation chromatography (GPC) as follows.

First, a crystalline polyester, amorphous saturated polyester resin or toner is dissolved in tetrahydrofuran (THF) at room temperature. Then, the obtained solution is filtered through a solvent-resistant membrane filter "Maeshori Disk" (manufactured by Tosoh Corporation) having a pore diameter of 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of THF-soluble components is 0.8% by mass. This sample solution is used for measurement under the following conditions.
Apparatus: High-speed GPC apparatus "HLC-8220GPC" [manufactured by Tosoh Corporation]
Column: Duplicate LF-604 Eluent: THF
Flow rate: 0.6ml/min
Oven temperature: 40°C
Sample injection volume: 0.020 ml

In calculating the molecular weight of the sample, standard polystyrene resin (for example, trade name "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F- 10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500", manufactured by Tosoh Corporation).

<Method for measuring acid value of crystalline polyester>
The acid value is mg of potassium hydroxide required to neutralize the acid contained in 1 g of sample. The acid value of the crystalline polyester was measured according to JIS K 0070-1992. Specifically, it was measured according to the following procedure.

(1) Preparation of Reagent 1.0 g of phenolphthalein was dissolved in 90 ml of ethyl alcohol (95% by volume), and deionized water was added to make 100 ml to obtain a phenolphthalein solution.

7 g of special grade potassium hydroxide was dissolved in 5 ml of water, and ethyl alcohol (95% by volume) was added to make 1 L. It was placed in an alkali-resistant container so as not to come in contact with carbon dioxide gas, etc., and was left to stand for 3 days, followed by filtration to obtain a potassium hydroxide solution. The resulting potassium hydroxide solution was stored in an alkali-resistant container. The factor of the potassium hydroxide solution was obtained by taking 25 ml of 0.1 mol/L hydrochloric acid in an Erlenmeyer flask, adding a few drops of the phenolphthalein solution, and titrating with the potassium hydroxide solution. It was determined from the amount of potassium solution. The 0.1 mol/L hydrochloric acid used was prepared according to JIS K 8001-1998.

(2) Operation (A) Main test 2.0 g of a pulverized crystalline polyester sample was precisely weighed in a 200 ml Erlenmeyer flask, 100 ml of a mixed solution of toluene: ethanol (2: 1) was added, and dissolved over 5 hours. . Then, several drops of the phenolphthalein solution were added as an indicator, and titration was performed using the potassium hydroxide solution. The end point of the titration was defined as when the light red color of the indicator continued for about 30 seconds.

(B) Blank test Titration was performed in the same manner as described above except that no sample was used (that is, only a mixed solution of toluene:ethanol (2:1) was used).

(3) The acid value was calculated by substituting the obtained results into the following formula.
A = [(CB) x f x 5.61]/S

Here, A: acid value (mgKOH / g), B: added amount of potassium hydroxide solution for blank test (ml), C: added amount of potassium hydroxide solution for main test (ml), f: potassium hydroxide Solution factor, S: sample (g).

Examples are shown below. Examples 3 to 9 are reference examples.

A method for manufacturing toner will be described in detail.

<Production example of magnetic iron oxide>
50 liters of an aqueous solution of ferrous sulfate containing 2.0 mol/L of Fe ²⁺ was mixed with 55 liters of an aqueous solution of 4.0 mol/L of sodium hydroxide to obtain a ferrous salt aqueous solution containing a ferrous hydroxide colloid. got This aqueous solution was kept at 85° C. and an oxidation reaction was carried out while blowing air at 20 L/min to obtain a slurry containing core particles.

After filtering and washing the resulting slurry with a filter press, the core particles were re-dispersed in water and re-slurried. To this reslurry liquid, sodium silicate having a content of 0.20% by mass in terms of silicon per 100 parts by mass of the core particles is added, the pH of the slurry liquid is adjusted to 6.0, and the magnetic particles having a silicon-rich surface are stirred. Iron oxide particles were obtained. The resulting slurry was filtered by a filter press, washed, and reslurried with deionized water. To this reslurry liquid (solid content: 50 g/L), 500 g (10% by mass relative to the magnetic iron oxide) of ion exchange resin SK110 (manufactured by Mitsubishi Chemical) was added and stirred for 2 hours to perform ion exchange. Thereafter, the ion-exchange resin was removed by filtration through a mesh, filtered and washed with a filter press, dried and pulverized to obtain magnetic iron oxide having a number average diameter of 0.23 μm.

<Production of silane compound>
30 parts by mass of iso-butyltrimethoxysilane was added dropwise to 70 parts by mass of ion-exchanged water while stirring. Thereafter, this aqueous solution was maintained at pH 5.5 and temperature 55° C., and hydrolyzed by dispersing for 120 minutes at a peripheral speed of 0.46 m/s using a disper blade. After that, the pH of the aqueous solution was adjusted to 7.0, and the hydrolysis reaction was stopped by cooling to 10°C. An aqueous solution containing a silane compound was thus obtained.

<Production of Magnetic Body 1>
100 parts by mass of magnetic iron oxide was placed in a high-speed mixer (Model LFS-2, manufactured by Fukae Powtec Co., Ltd.), and while stirring at 2000 rpm, 8.0 parts by mass of an aqueous solution containing a silane compound was added dropwise over 2 minutes. . After that, the mixture was mixed and stirred for 5 minutes. Next, in order to increase the adhesion of the silane compound, it was dried at 40° C. for 1 hour to reduce the water content, and then the mixture was dried at 110° C. for 3 hours to allow the condensation reaction of the silane compound to proceed. After that, it was pulverized and sieved through a sieve with an opening of 100 μm to obtain a magnetic body 1 .

<Manufacturing Example of Magnetic Body 2>
In the ferrous sulfate aqueous solution, 1.00 to 1.10 equivalents of a caustic soda solution with respect to the iron element, P ₂ O ₅ in an amount that is 0.15% by mass in terms of phosphorus element with respect to the iron element, An aqueous solution containing ferrous hydroxide was prepared by mixing SiO ₂ in an amount of 0.50% by mass in terms of silicon element. The pH of the aqueous solution was adjusted to 8.0, and an oxidation reaction was carried out at 85° C. while blowing air into the solution to prepare a slurry containing seed crystals.

Next, after adding an aqueous solution of ferrous sulfate to the slurry liquid so that the amount of alkali (sodium component of caustic soda) is 0.90 to 1.20 equivalents, the slurry liquid is maintained at pH 7.6, The oxidation reaction was proceeded while blowing air, and a slurry liquid containing magnetic iron oxide was obtained. After filtration and washing, this water-containing slurry liquid was once taken out. At this time, a small amount of water-containing sample was taken and the water content was measured. Next, the water-containing sample is put into another aqueous medium without drying, and re-dispersed with a pin mill while stirring and circulating the slurry, and the pH of the re-dispersed liquid is adjusted to about 4.8. Then, while stirring, 1.4 parts by mass of an n-hexyltrimethoxysilane coupling agent was added to 100 parts by mass of magnetic iron oxide (the amount of magnetic iron oxide was calculated by subtracting the water content from the water-containing sample). , hydrolysis was carried out. After that, the dispersion was sufficiently agitated, and the pH of the dispersion was adjusted to 8.6 to carry out the surface treatment. The produced hydrophobic magnetic material is filtered with a filter press, washed with a large amount of water, dried at 100° C. for 2 hours, and the obtained particles are pulverized to obtain a magnetic material having a volume average particle size of 0.26 μm. got 2.

<Manufacturing Example of Magnetic Body 3>
An aqueous solution was prepared by dropping 20 parts by mass of dodecyltrimethoxysilane into 80 parts by mass of ion-exchanged water while stirring. After that, the pH of this aqueous solution is set to 6.2, and while the temperature is kept at 61° C., hydrolysis is performed by dispersing at 0.46 m / s for 3 hours using a disper blade to obtain an aqueous solution containing a hydrolyzate. A silane compound was obtained.

After putting the magnetic iron oxide into a Henschel mixer (Nippon Coke Industry Co., Ltd. (formerly Mitsui Miike Kakoki Co., Ltd.)), a silane compound (3 .8 parts by mass) was added while spraying.Next, after being dispersed as it was for 10 minutes, the magnetic material with the silane compound adsorbed was taken out and left quietly at 160°C for 2 hours to dry the magnetic material. At the same time, the condensation reaction of the silane compound was allowed to proceed, and the magnetic material was passed through a sieve with an opening of 100 μm to obtain a magnetic material 3 as magnetic material 3 .

<Manufacturing Example of Magnetic Body 4>
An aqueous solution was prepared by dropping 20 parts by mass of methyltrimethoxysilane into 80 parts by mass of ion-exchanged water while stirring. After that, the pH of this aqueous solution is set to 5.3, and while the temperature is maintained at 40° C., hydrolysis is performed by dispersing at 0.46 m / s for 100 minutes using a disper blade to obtain an aqueous solution containing a hydrolyzate. A silane compound was obtained.

After putting the magnetic iron oxide into a Henschel mixer (Nippon Coke Industry Co., Ltd. (formerly Mitsui Miike Kakoki Co., Ltd.)), a silane compound (3 .8 parts by mass) was added while spraying.Next, after being dispersed as it was for 10 minutes, the magnetic material with the silane compound adsorbed was taken out and left quietly at 160°C for 2 hours to dry the magnetic material. At the same time, the condensation reaction of the silane compound was allowed to proceed, and the magnetic material was passed through a sieve with an opening of 100 μm to obtain a magnetic material 4 .

<Production example of polyester resin>
40 mol% of terephthalic acid, 10 mol% of trimellitic acid, and 50 mol% of bisphenol A-PO2 mol adduct were placed in a reactor equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and dibutyltin was added as a catalyst to the monomer. 1.5 parts by mass was added with respect to 100 parts by mass of the total amount. Then, the temperature was quickly raised to 180° C. under normal pressure in a nitrogen atmosphere, and then water was distilled off while heating from 180° C. to 210° C. at a rate of 10° C./hour to carry out polycondensation. After the temperature reached 210° C., the pressure in the reactor was reduced to 5 kPa or less, and polycondensation was carried out at 210° C. and 5 kPa or less to obtain an amorphous polyester resin. At that time, the polymerization time was adjusted so that the softening point of the resulting polyester resin was 120°C.

<Production example of crystalline polyester 1>
49 mol% of 1,9-nonanediol, 49 mol% of 1,10-decanedioic acid, and 2 mol% of n-octadecanoic acid were placed in a reactor equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and then 1 part by mass of tin dioctate as a catalyst was added to 100 parts by mass of the total amount of monomers, heated to 140° C. under a nitrogen atmosphere, and reacted for 6 hours under normal pressure while distilling off water. Next, the temperature was raised to 200° C. at a rate of 10° C./hour, and the reaction was allowed to proceed. After reaching 200° C., the reaction was allowed to proceed for 2 hours. A synthetic polyester 1 was obtained. The crystalline polyester had an acid value of 2.2 and a molecular weight (Mw) of 34,200.

<Production example of crystalline polyester 2>
Crystalline polyester 2 having an acid value of 5.0 and a molecular weight (Mw) of 12,000 was obtained by changing the reaction temperature, monomer ratio, reaction time, and amount of catalyst in the production example of crystalline polyester 1.

<Production example of crystalline polyester 3>
Using 1,6-hexanediol as the alcohol monomer and 1,12-dodecanedioic acid as the acid monomer, and further changing the reaction temperature, the monomer ratio, the reaction time, and the amount of the catalyst, in the same manner as in the production example of the crystalline polyester 1, A crystalline polyester 3 having an acid value of 7.9 and a molecular weight of 22,000 was obtained.

<Production Example of Magnetic Toner 1>
Toner particles and toner were produced by the following procedure.

(Preparation of first aqueous medium)
Add 2.9 parts by mass of sodium phosphate dodecahydrate to 353.8 parts by mass of ion-exchanged water and heat to 60°C while stirring using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). After that, an aqueous calcium chloride solution obtained by adding 1.7 parts by mass of calcium chloride dihydrate to 11.7 parts by mass of ion-exchanged water, and 0.5 parts by mass of magnesium chloride to 15.0 parts by mass of ion-exchanged water were added. An aqueous magnesium chloride solution was added and stirring was continued to obtain a first aqueous medium containing dispersion stabilizer A.

(Preparation of polymerizable monomer composition)
・Styrene 75.0 parts by mass ・n-Butyl acrylate 25.0 parts by mass ・1-6 Hexanediol diacrylate 0.5 parts by mass ・Magnetic substance 1 95.0 parts by mass ・Polyester resin 5.0 parts by mass After uniformly dispersing and mixing using an attritor (manufactured by Mitsui Miike Kakoki Co., Ltd.), the mixture was heated to 60°C, and 15.0 parts by mass of behenyl stearate wax (melting point: 68°C) as an ester wax was added thereto and carbonized. 8.0 parts by mass of paraffin wax (manufactured by Nippon Seiro Co., Ltd., HNP-9) as hydrogen wax was added and mixed and dissolved to obtain a polymerizable monomer composition.

(Preparation of second aqueous medium)
After adding 0.6 parts by mass of sodium phosphate dodecahydrate to 166.8 parts by mass of ion-exchanged water and heating to 60°C while stirring using a paddle stirring blade, 2.3 parts by mass of ion-exchanged water. A second aqueous medium containing dispersion stabilizer B was obtained by adding an aqueous calcium chloride solution to which 0.3 parts by mass of calcium chloride dihydrate was added and stirring was continued.

(granulation)
The polymerizable monomer composition is added to the first aqueous medium, and the granulation liquid is treated with Cavitron (manufactured by Eurotech) for 1 hour at a rotor peripheral speed of 29 m/s. Then, uniformly dispersed and mixed, 7.0 parts by mass of t-butyl peroxypivalate is added as a polymerization initiator, and the mixture is rotated at 60 ° C. under a _N atmosphere with Clearmix (manufactured by M Technic Co., Ltd.). The mixture was granulated with stirring at a speed of 22 m/s for 10 minutes to obtain a granulation liquid containing droplets of the polymerizable monomer composition.

(polymerization/distillation/drying/external addition)
The granulation liquid was added to the second aqueous medium, and the mixture was reacted at 74° C. for 3 hours while being stirred with a paddle stirring blade. After completion of the reaction, the mixture was heated to 98° C. and distilled for 3 hours to obtain a reaction slurry. Thereafter, as a cooling step, water of 0° C. was added to the reaction slurry, and after cooling the reaction slurry from 98° C. to 45° C. at a rate of 100° C./min, the temperature was further raised and held at 50° C. for 3 hours. After that, it was allowed to cool to 25°C at room temperature. The cooled reaction slurry was washed with hydrochloric acid, filtered and dried to obtain toner particles having a weight average particle diameter of 7.4 μm. The weight average particle size of the toner particles of Toners 2 to 21 below was 7.2 to 7.5 μm.

Toner 1 was obtained by mixing 100 parts by mass of the obtained toner particles with the following materials using a Henschel mixer (Model FM-10 manufactured by Mitsui Miike Kakoki Co., Ltd.).
・0.5 parts by mass of hydrophobic silica fine particles having a number average particle size of 20 nm of primary particles surface-treated with 25% by mass of hexamethyldisilazane ・Number average particle size of 40 nm of primary particles surface-treated with 15% by mass of hexamethyldisilazane 0.5 parts by mass of hydrophobic silica fine particles

Table 1 shows the physical properties of Toner 1 obtained.

<Manufacturing Examples of Magnetic Toners 2 to 8 and 10 to 19>
Magnetic Toners 2 to 8 and 10 to 19 were obtained in the same manner as in Production Example of Magnetic Toner 1, except that the material composition and production conditions shown in Table 2 were used. Table 1 shows the physical properties of the obtained magnetic toner.

<Production Example of Magnetic Toner 9>
In Production Example of Magnetic Toner 1, a magnetic toner was produced in the same manner as in Production Example of Magnetic Toner 1, except that the material composition and production conditions were as shown in Table 2, and the cooling rate of the reaction slurry was changed to 1° C./min. Toner 9 was obtained. Table 1 shows the physical properties of the obtained magnetic toner.

<Production Example of Magnetic Toner 20>
After adding 450 parts by mass of 0.1 mol/L-Na ₃ PO ₄ aqueous solution to 720 parts by mass of ion-exchanged water and heating to 60° C., 67.7 parts by mass of 1.0 mol/L-CaCl ₂ aqueous solution was added. to obtain an aqueous medium containing a dispersion stabilizer.

・Styrene 78 parts by mass ・n-Butyl acrylate 22 parts by mass ・Divinylbenzene 0.5 parts by mass ・Polyester resin 3 parts by mass ・Negative charge control agent T-77 (manufactured by Hodogaya Chemical) 1 part by mass ・Magnetic substance 1 90 parts by mass The above formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Kakoki Co., Ltd.). This monomer composition was heated to a temperature of 60° C., and 15 parts by mass of paraffin wax (HNP-9: manufactured by Nippon Seiro Co., Ltd.) as a release agent and di-secondary butylperoxy as a polymerization initiator were added. 4 parts by mass of a dicarbonate (10-hour half-life temperature of 51° C.) was mixed and dissolved to obtain a polymerizable monomer composition.

The polymerizable monomer composition is added to the aqueous medium, and stirred at 10,000 rpm for 15 minutes with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) under _N2 atmosphere at a temperature of 60°C. Granulated. Thereafter, the mixture was stirred with a paddle stirring blade, and the polymerization reaction was carried out for 360 minutes at a reaction temperature of 70°C (a temperature 19°C higher than the 10-hour half-life temperature of the polymerization initiator). Thereafter, the suspension was cooled to room temperature at a rate of 3° C. per minute, and hydrochloric acid was added to dissolve the dispersant, filtered, washed with water, and dried to obtain toner particles.

After that, magnetic toner 20 was obtained in the same manner as in the manufacturing example of magnetic toner 1 .

<Production Example of Magnetic Toner 21>
After adding 451 parts by mass of 0.1M-Na ₃ PO ₄ aqueous solution to 720 parts by mass of ion-exchanged water and heating to 60°C, 67.7 parts by mass of 1.0M-CaCl ₂ aqueous solution was added to stabilize the dispersion. An aqueous medium containing the agent was obtained.

・Styrene 75.0 parts by mass ・n-Butyl acrylate 25.0 parts by mass ・1,6-Hexanediol diacrylate 0.50 parts by mass ・Iron complex of monoazo dye (T-77: manufactured by Hodogaya Chemical Co., Ltd.) 1.0 Parts by mass Magnetic substance 1 90.0 parts by mass Polyester resin 5.0 parts by mass (saturated polyester resin obtained by condensation reaction of 2.0 mol adduct of ethylene oxide of bisphenol A and terephthalic acid; number average molecular weight (Mn ) = 5000, acid value = 12 mg KOH / g, glass transition temperature (Tg) = 68 ° C.)
The above components were uniformly dispersed and mixed using an attritor (manufactured by Mitsui Miike Kakoki Co., Ltd.) to obtain a monomer composition. This monomer composition was heated to 60° C., and 15.0 parts by mass of behenyl behenyl wax (melting point: 73° C.) was mixed and dissolved therein. Part by mass was dissolved.

The monomer composition was added to the aqueous medium, and stirred at 18.8 m/s for 10 minutes at 60°C under a _N atmosphere with a TK-type homomixer (Tokushu Kika Kogyo Co., Ltd.). Grained.

Thereafter, while stirring with a paddle stirring blade, the mixture was stirred with a paddle stirring blade, and the reaction step was carried out at a temperature of 70°C (a temperature higher than the 10-hour half-life temperature of the polymerization initiator by 17°C). The reaction process was terminated when the reaction time was 300 minutes.

After completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve the dispersant, filtered, washed with water and dried to obtain toner particles.

After that, magnetic toner 21 was obtained in the same manner as in the manufacturing example of magnetic toner 1 .

Next, examples and comparative examples will be described in detail.

<Example 1>
A commercially available laser printer LaserJet Enterprise M506 (manufactured by Hewlett-Packard Co.) was used for image output evaluation in the examples. The cartridge was removed from the main body, the product toner was extracted from the cartridge, and 300 g of toner 1 was filled. The main body and the cartridge were left for 24 hours in a temperature-and-humidity-controlled environment, and then evaluated for image reproduction. Regarding the image output evaluation, the following evaluation was performed and judgment was made according to the following indices. Table 3 shows the evaluation results.

(1) Evaluation of developability under low temperature and low humidity (15°C and 10% RH) After passing 10 sheets of paper with a horizontal line image with a printing ratio of 1%, a solid white image is printed on both sides, and the image on the second side is used for white background. The fogging density (%) was calculated from the difference between the white background area of the non-passage area and the non-passage area. For the fog measurement, TC-6DS (manufactured by Tokyo Denshoku Co., Ltd.) was used, and the average value of 5 points was defined as the fog concentration (%), which was judged by the following index. As the durability evaluation paper, business 4200 (manufactured by Xerox) having a basis weight of 75 g/m ² was used. Table 3 shows the evaluation results.
A: Less than 1.5% B: 1.5% or more and less than 2.0% C: 2.0% or more and less than 2.5% D: 2.5% or more and less than 3.0% E: 3.0% or more

(2) Evaluation of transfer residual density under high temperature and high humidity conditions (32.5° C., 80% RH) The main body was modified so that it can be changed between 2 and 20 μA in increments of 2 μA. After passing 10,000 sheets of paper with a horizontal line image with a printing ratio of 1%, the transfer current is changed between 2 and 20 μA in increments of 2 μA, and a solid image is output at each time, and the solid image is transferred onto the photoreceptor after transfer. The residual toner was taped with Mylar tape and stripped off.

The tape with taping was attached to a white paper, and the transfer residual density (%) was calculated from the difference from the tape without taping. TC-6DS (manufactured by Tokyo Denshoku Co., Ltd.) was used to measure the residual transfer density, and the average value of 5 points was defined as the residual transfer density (%), which was judged according to the following index. As the durability evaluation paper, business 4200 (manufactured by Xerox) having a basis weight of 75 g/m ² was used. Among the values of 2 to 20 μA, the value of the one with the largest amount of transfer residue was ranked below and evaluated. Table 3 shows the evaluation results.
A: Less than 1.0% B: 1.0% or more and less than 2.0% C: 2.0% or more and less than 3.0% D: 3.0% or more and less than 4.0% E: 4.0% or more

(3) Evaluation of fixability under normal temperature and humidity (23°C and 50% RH) FOX RIVER BOND paper (110 g/m ² ) was used as the fixing medium, and LBP3410 (a monochrome laser beam printer manufactured by Canon Inc.) was used as the image forming apparatus. printer) modified so that the development bias can be adjusted. A line image is used as the evaluation image. The amount of toner on the image is increased by setting the reflection density of the image area high by swinging the development bias, and by using thick paper with a relatively large surface unevenness, the recesses of the paper and the lower layer of the toner layer in the fixing process Since the toner becomes difficult to melt, peeling can be evaluated severely. As for the evaluation environment, if the temperature is low, it is difficult for the fixing device to warm up, resulting in a severe evaluation.

The evaluation procedure is shown below. First, the image forming apparatus was left overnight in a low-temperature, low-humidity environment (temperature: 15° C., humidity: 10%). After that, using FOX RIVER BOND paper, a horizontal line image is printed with the development bias adjusted so that the line width becomes 180 μm. Further, after being left for 1 hour in a low-temperature and low-humidity environment, a polypropylene tape (Klebeband 19 mm×10 mm, manufactured by tesa) was attached to the horizontal line image and slowly peeled off. The image after peeling was visually and microscopically observed and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 3.
A: No defects B: Defects are slightly visible, but not visually noticeable C: Defects that can be visually recognized are slightly visible D: Defects are visually recognizable, and there is a part where the line is interrupted E: There are many breaks in the line

<Examples 2 to 9, Comparative Examples 1 to 12>
Evaluation was performed in the same manner as in Example 1, except that the toner was changed as shown in Table 2. Table 3 shows the evaluation results.

100: electrostatic latent image carrier (photoreceptor), 102: toner carrier, 114: transfer member (transfer roller), 116: cleaning member (cleaning blade), 117: charging member (charging roller), 121: laser generation Apparatus (Latent Image Forming Means, Exposure Device) 123: Laser 124: Pickup Roller 125: Conveyor Belt 126: Fixing Device 140: Developing Device 141: Toner Stirring Member 142: Toner Regulating Member A2: Casing , A8: holding tank, A10: circulation pump, A22: stator, A25: rotor

Claims (2)

A magnetic toner having toner particles containing a binder resin, wax, and a magnetic material,
The wax contains a hydrocarbon wax and behenyl stearate ,
The magnetic toner has a surface vicinity abundance index of 5 or more and 8 or less, and a standard deviation of the surface vicinity abundance of 0.7 or more and 2.5 or less, obtained by observing the magnetic toner with an SEM. and
70 area % or more and 100 area % or less of the magnetic material within 30% of the distance between the contour and the center point of the cross section from the contour of the cross section in the cross section of the magnetic toner observed with a transmission electron microscope. exist ,
A magnetic toner characterized by: 2. The magnetic toner according to claim 1, wherein the near-surface existence index is 5 or more and 6 or less.

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