JP4856985B2 - toner - Google Patents

Description

  The present invention relates to a toner used in a recording method using an electrophotographic method or an electrostatic recording method. More specifically, the electrostatic latent image formed on the electrostatic latent image carrier is developed with toner to form a toner image on the electrostatic latent image carrier, and the toner image on the electrostatic latent image carrier is formed. It relates to toner used in copying machines, printers or fax machines that transfer a toner image onto a transfer material with or without an intermediate transfer member and fix the toner image on the transfer material to form a fixed image. is there.

Conventionally, in toners used for electrophotographic methods and electrostatic recording methods, inorganic fine particles are added to toner particles for the purpose of obtaining good developability, cleaning properties, and transferability by adjusting the chargeability and fluidity of the toner. It is generally known to add externally.
The characteristics of the toner greatly depend on the characteristics of the external additive itself, the amount of the external additive added to the toner particles, the presence state of the external additive in the toner, and the like. In particular, since the characteristics of the external additive itself greatly affect the characteristics of the toner, many investigations and proposals have been made on the external additive itself.

  As inorganic fine particles used as external additives, metal oxides are frequently used, and silica, titanium oxide, alumina, zinc oxide, strontium titanate, etc. are common. Among such external additives, use of magnesium oxide is disclosed (see, for example, Patent Documents 1 to 4). In particular, Patent Document 1 shows that the use of magnesium oxide as an external additive improves fogging and toner scattering.

  However, in the above conventional example, stable developability was confirmed in an environment where the temperature was 10 ° C. to 30 ° C. and the humidity was about 5 to 80%. However, in a continuous print test under a high temperature and high humidity environment, Due to the deterioration of the charging property, fogging, low density, and toner scattering occurred, and the developability was not at a satisfactory level. Further, it has been found that when continuous printing is alternately repeated in a high humidity environment and a low humidity environment, filming (the toner adheres to the surface of the latent electrostatic image bearing member) occurs.

The reason for this is considered as follows.
(1) When continuous printing is performed in a high temperature environment, the inside of the apparatus becomes hot. In particular, the heat generated inside the apparatus increases as the printing speed increases. On the other hand, the heat generated inside the apparatus is less likely to be dissipated due to the downsizing of the apparatus. For this reason, the tendency of the inside of the apparatus to become high temperature is remarkable, and the toner is deteriorated by this heat. In particular, when passing through the development area, the heat from the electrostatic latent image bearing member is also received. Therefore, when the toner returns to the developing unit without being developed, the toner deteriorates in chargeability, and again. It is considered that fogging, thin density, toner scattering, filming, etc. occur during development.
(2) Magnesium oxide absorbs moisture in a high humidity environment and the surface partially changes to magnesium hydroxide. For this reason, it is considered that the good developability inherent to magnesium oxide is impaired. Further, since the Mohs hardness of magnesium oxide is as high as 6.5 (hard), external additives attached to the surface of the latent electrostatic image bearing member can be removed by continuous printing for a long time. This effect cannot be expected when is changed to magnesium hydroxide. This is considered to be because the Mohs hardness of magnesium hydroxide is as low as 2.5 (soft).

In addition, about the manufacturing method of the forsterite mentioned later, the method (refer patent document 5 and patent document 6) which manufactures from the solution which contains magnesium and silicon in the molar ratio 2: 1, respectively is proposed.
JP-A-5-216269 JP-A-8-36271 JP-A-8-137125 JP 11-327194 A JP 2003-2640 A JP 2003-327470 A

  Accordingly, an object of the present invention is to provide a toner that solves the above-mentioned problems. That is, an object of the present invention is to provide a toner that can produce a good image without fogging, low density and toner scattering even in an environment exposed to high temperature and high humidity. Furthermore, an object of the present invention is to provide a toner that does not cause filming and can provide a good image even when continuous printing is repeated alternately in a high-humidity environment and a low-humidity environment.

The above object is achieved by the present invention described below. That is, the present invention
(1) and the toner base particles containing at least a binder resin and a magnetic material, a magnetic toner comprising an inorganic fine particle, the magnetic toner or at least one inorganic fine particles are characterized in that the forsterite.
(2) The ratio of the peak intensity of 26.5 deg and 42.9 deg to the peak intensity of Bragg angle (2θ ± 0.2 deg) of 36.4 deg in CuKα characteristic X-ray diffraction of the forsterite is 0.1. The magnetic toner according to (1), wherein:
(3) The magnetic toner according to (1) or (2), wherein the primary particle diameter of the forsterite is 0.05 μm or more and 0.50 μm or less.
(4) The magnetic toner according to any one of (1) to (3), wherein the surface of the forsterite is hydrophobized.
(5) The ratio of the peak intensity of 26.5 deg and 42.9 deg to the peak intensity of Bragg angle (2θ ± 0.2 deg) of 36.4 deg in CuKα characteristic X-ray diffraction of the forsterite is 0.001. The magnetic toner according to any one of (1) to (4), wherein:
(6) The amount of the forsterite added is 0.05 to 5.00 parts by mass with respect to 100 parts by mass of the toner base particles. The magnetic toner described in 1.

  According to the present invention, even in an environment exposed to high temperature and high humidity, a good image can be obtained without fogging, low density and toner scattering. Even when continuous printing is repeated alternately in a high humidity environment and a low humidity environment, filming does not occur and a good image can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.

The present invention is a toner comprising toner base particles containing at least a binder resin and a colorant, and inorganic fine particles, wherein at least one of the inorganic fine particles is forsterite (2 (MgO) SiO ₂ ). The toner is characterized by the above.

  The method for producing toner base particles used in the toner of the present invention is not particularly limited, and suspension polymerization, emulsion polymerization, association polymerization, and kneading and pulverization may be used.

  Hereinafter, a method for producing toner base particles by suspension polymerization will be described.

  A colorant, a low softening point material such as wax, a polar resin, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and if necessary, the solution is uniformly dissolved or dispersed by a homogenizer or an ultrasonic disperser. The monomer composition is dispersed in an aqueous phase containing a dispersion stabilizer by a stirrer, a homogenizer or a homomixer. At this time, granulation is preferably performed by adjusting the stirring speed and time so that the droplets of the monomer composition have the desired toner base particle size. The size of the toner base particles is preferably 3 μm to 9 μm, more preferably 4 μm to 7 μm. After that, stirring may be performed to such an extent that the particle state of the monomer composition is maintained by the action of the dispersion stabilizer and precipitation of the particles of the monomer composition is prevented.

  The polymerization temperature is preferably set to 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the second half of the polymerization reaction, and in order to remove unreacted polymerizable monomers and by-products that cause odor during toner fixing, some water may be added in the second half of the reaction or at the end of the reaction. Alternatively, a part of the aqueous medium may be distilled off. After completion of the reaction, the produced toner base particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3,000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition.

  The particle size distribution control and particle size control of the toner base particles can be controlled by adjusting the pH of the aqueous medium during granulation, changing the type and amount of the hardly water-soluble inorganic salt and the dispersing agent acting as a protective colloid, This can be achieved by controlling the peripheral speed of the rotor of the apparatus, the number of passes, the shape of the stirring blade, the stirring conditions, the container shape or the solid content concentration in the aqueous solution.

  Examples of the polymerizable monomer used for suspension polymerization include styrene; styrene derivatives such as o- (m-, p-) methylstyrene and m- (p-) ethylstyrene; methyl (meth) acrylate, (meta ) Propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, (meth) acrylate-2-ethylhexyl, Examples include (meth) acrylic acid ester monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; butadiene, isoprene, cyclohexene, (meth) acrylonitrile, and acrylamide.

  As the polar resin used for suspension polymerization, a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a polyester resin, and an epoxy resin are preferably used. A preferable addition amount of the polar resin is 0.5 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Low softening point materials such as waxes used for suspension polymerization include paraffin waxes, polyolefin waxes, Fischer-Tropsch waxes, amide waxes, higher fatty acids, ester waxes and derivatives thereof, or graft / block compounds thereof. . A preferable addition amount of the low softening point substance such as wax is 1 to 30 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  As the charge control agent used for the suspension polymerization, known charge control agents can be used, but a charge control agent having no polymerization inhibition and no soluble component in an aqueous medium is particularly preferable. Examples of the charge control agent include negative charge control agents and positive charge control agents. Specific examples of the negative compound include salicylic acid, naphthoic acid, dicarboxylic acid, metal compounds of derivatives thereof, polymer compounds having sulfonic acid in the side chain, boron compounds, urea compounds, silicon compounds, calixarene. . Examples of the positive system include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, and an imidazole compound. The amount of the charge control agent used is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  As polymerization initiators used for suspension polymerization, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1- Carbonitrile), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo-based polymerization initiators such as azobisisobutylnitrile; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroxyperoxide, 2 And peroxide polymerization initiators such as 1,4-dichlorobenzoyl peroxide and lauroyl peroxide. Although the addition amount of this polymerization initiator changes with the target degree of polymerization, generally the ratio of 0.5-20 mass parts (polymerizable monomer reference | standard) with respect to 100 mass parts of polymerizable monomers. Used in The kind of the polymerization initiator is slightly different depending on the polymerization method, but may be used alone or mixed with reference to the 10-hour half-life temperature.

  Examples of the dispersant used for suspension polymerization include inorganic oxides and organic compounds. Inorganic oxides include calcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite , Silica, alumina, magnetic material, and ferrite. Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, and starch. These dispersants are preferably used in a proportion of 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

A commercially available dispersant may be used as it is, but in order to obtain a dispersant having a fine and uniform particle size, it can also be obtained by producing an inorganic compound in a dispersion medium under high-speed stirring. For example, in the case of calcium phosphate, a dispersant preferable for the suspension polymerization method can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high-speed stirring.
In order to refine these dispersants, 0.001 to 0.1 parts by mass of a surfactant may be used in combination with 100 parts by mass of the suspension. Specifically, commercially available nonionic, anionic and cationic surfactants can be used. Examples of the surfactant include sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, and calcium oleate.

The following are mentioned as a coloring agent used for suspension polymerization.
As the black colorant, carbon black, a magnetic material, and a color toned to black using a yellow / magenta / cyan colorant shown below are used.

  As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complex methine compounds, and allylamide compounds are used as pigments. Specifically, C.I. I. Pigment Yellow 3, 7, 10, 12, 13, 14, 15, 17, 23, 24, 60, 62, 74, 75, 83, 93, 94, 95, 99, 100, 101, 104, 108, 109, 110 111,117,123,128,129,138,139,147,148,150,166,168,169,177,179,180,181,183,185,191: 1,191,192,193,199 Are preferably used. Examples of the dye system include C.I. l. solventYellow33, 56, 79, 82, 93, 112, 162, 163, C.I. I. disperse Yellow 42.64.2011.211.

As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254, C.I. I. Pigment Bio Red 19 is particularly preferable.

  As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, and 66 are particularly preferably used.

  Next, an example of a method for producing toner base particles by a pulverization method will be described.

  Binder resin, mold release agent, charge control agent, colorant, etc. are thoroughly mixed by a mixer such as a Henschel mixer or ball mill, and then melt-kneaded using a heat kneader such as a heating roll, kneader or extruder. , Disperse or dissolve the charge control agent and colorant in the resin compatible with each other, cool and solidify, then mechanically pulverize to the desired particle size, and further sharpen the particle size distribution of the finely pulverized product by classification To do. Alternatively, after cooling and solidification, a finely pulverized product obtained by colliding with a target under a jet stream is spheroidized by heat or mechanical impact force.

  Examples of the binder resin used in the pulverization method include polystyrene, poly-α-methylstyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, and styrene-vinyl acetate copolymer. Styrene-acrylic acid ester copolymer, styrene-methacrylic acid acrylic copolymer, vinyl chloride resin, polyester resin, epoxy resin, phenol resin, polyurethane resin. These are used alone or in combination. Of these, styrene-acrylic copolymer resins, styrene-methacrylic copolymer resins, and polyester resins are preferred.

Examples of the charge control agent used in the pulverization method include the following. The charge control agent for controlling the toner base particles to be positively charged includes a modified product of a fatty acid metal salt; quaternary ammonium such as tributylbenzidylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate. Salts; phosphonium salts such as tributylbenzidylphosphonium-1-hydroxy-4-naphthosulfonate, tetrabutylphosphonium tetrafluoroborate; amine and polyamine compounds; metal salts of higher fatty acids; acetylacetone metal complexes; dibutyltin oxide, dioctyltin Diorganotin oxides such as oxide and dicyclohexyltin oxide; and diorganotin borates such as dibutyltin borate, dioctyltin borate and dicyclohexyltin borate As the charge control agent for controlling the toner base particles to be negatively charged, organometallic complexes and chelate compounds are effective, and examples include metal complexes of monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acids. .
The amount of these charge control agents used is 0.1 to 15 parts by mass, preferably 0.1 to 10 parts by mass, with respect to 100 parts by mass of the binder resin.

A low softening point substance such as a release agent can be added to the toner base particles produced by the pulverization method, if necessary. Low softening point substances include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, paraffin wax, and Fischer-Tropsch wax or their oxides; aliphatic esters such as carnauba wax and montanate wax. And wax obtained by deoxidizing a part or all of the wax. Furthermore, saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brandic acid, eleostearic acid, and valinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvyl alcohol, and seryl alcohol Saturated alcohols such as melisyl alcohol; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide; saturated fatty acid bisamides such as methylenebisstearic acid amide; unsaturated fatty acid amides such as ethylene bisoleic acid amide Aromatic bisamides such as N, N′-distearylisophthalamide; fatty acid metal salts such as zinc stearate; waxes grafted to aliphatic hydrocarbon waxes using vinyl monomers such as styrene; Examples include partially esterified products of fatty acids such as behenic acid monoglyceride and polyhydric alcohols; methyl esterified products having hydroxyl groups obtained by hydrogenation of vegetable oils and fats. The addition amount of the low softening point substance is 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

Examples of the colorant used in the pulverization method include the following.
As the black colorant, carbon black, a magnetic material, and a color toned to black using a yellow / magenta / cyan colorant shown below are used.

  As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complex methine compounds, and allylamide compounds are used as pigments. Specifically, C.I. I. Pigment Yellow 3, 7, 10, 12, 13, 14, 15, 17, 23, 24, 60, 62, 74, 75, 83, 93, 94, 95, 99, 100, 101, 104, 108, 109, 110 111,117,123,128,129,138,139,147,148,150,166,168,169,177,179,180,181,183,185,191: 1,191,192,193,199 Are preferably used. Examples of the dye system include C.I. l. solventYellow33, 56, 79, 82, 93, 112, 162, 163, C.I. I. disperse Yellow 42.64.2011.211.

  As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254, C.I. I. Pigment Bio Red 19 is particularly preferable.

  As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, and 66 are particularly preferably used.

  The toner of the present invention is obtained by externally adding at least one or more types of forsterite to the toner base particles thus obtained.

The amount of forsterite added is preferably 0.05 to 5.00 parts by mass with respect to 100 parts by mass of toner base particles. If the amount added is less than 0.05 parts by weight, the effect that fogging, low density, toner scattering, and filming do not occur may be small. If the amount exceeds 5.00 parts by weight, the contamination of the charging member may be somewhat worsened. There is.

As described above, when continuous printing is performed in a high temperature environment, the toner deteriorates due to this heat. In particular, it is considered that the influence of heat upon passing through the development area is large. Although the time required to pass through the development area is very short, the thermal conductivity of magnesium oxide is about 35 W / mK, which is easy to transfer heat, so the heat is conducted to the inside of the toner base particles to control the charging of the toner resin or toner. Heat is applied to the charge control agent and the like, and the toner cannot exhibit desired chargeability. For this reason, it is considered that fogging, density reduction, toner scattering, and filming deteriorate.

  The thermal conductivity of forsterite used in the present invention is as small as about 5 W / mK, and the thermal conductivity of titanium oxide, alumina, zinc oxide, strontium titanate and the like generally used as external additives (about 12 to 50 W / mK) is also small. Therefore, when the time which receives the influence of heat is short as mentioned above, the outstanding heat insulation effect is exhibited.

  Forsterite has a high Mohs hardness of 6.5. Furthermore, the stability is high and there is no change due to moisture absorption like the magnesium oxide described above. For this reason, it is possible to satisfactorily remove external additives and the like attached to the surface of the latent electrostatic image bearing member even in continuous printing for a long time that is alternately repeated in a high and low humidity environment.

Forsterite is expressed by 2 (MgO) SiO ₂ , but when magnesium oxide (MgO) is present instead of a single phase, it absorbs moisture in a high humidity environment as described above and turns into magnesium hydroxide. It is not preferable because it changes.

Therefore, the forsterite used in the present invention has a ratio of the peak intensity of 26.5 deg and 42.9 deg to the peak intensity of 36.4 deg in Bragg angle (2θ ± 0.2 deg) in CuKα characteristic X-ray diffraction. It is preferable that it is 0.1 or less.
The peak at a Bragg angle of 36.4 deg in CuKα characteristic X-ray diffraction is a peak specific to forsterite. Similarly, 26.5 deg is a SiO ₂ peak and 42.9 deg is a MgO peak. The ratio of the peak intensity at 26.5 deg and the peak intensity at 42.9 deg with respect to the peak intensity at 36.4 deg is 0.1 or less, so that moisture is absorbed in a high humidity environment and changed to magnesium hydroxide. However, there is no significant influence on the toner characteristics.

  Forsterite is highly stable and does not change due to moisture absorption as in the case of magnesium oxide described above, but a decrease in the chargeability of forsterite itself due to the adsorption of moisture on the surface is observed. In this case, forsterite is liberated from the surface of the toner base particles, and the above-described heat insulation effect may be reduced. Therefore, the forsterite used in the present invention preferably has a hydrophobic surface.

  Although it does not specifically limit as a hydrophobization processing agent, A silane coupling agent, a silylating agent, a titanium coupling agent, a silicone oil etc. are mentioned, These may be used together.

In addition, when hydrophobizing the surface of forsterite, since the surface treatment may become non-uniform when magnesium oxide (MgO) or silica (SiO ₂ ) is present instead of a single phase, the forsterite of the present invention is It is more preferable that the ratio of the peak intensity of 26.5 deg and 42.9 deg to the peak intensity of Bragg angle (2θ ± 0.2 deg) of 36.4 deg in CuKα characteristic X-ray diffraction is 0.001 or less.

The X-ray diffraction measurement method of the present invention is performed by irradiating a sample surface with an X-ray beam as described in Basic Analytical Chemistry Course 24 “X-ray diffraction” (Kyoritsu Shuppan), etc. A method for identifying and quantifying crystalline substances by measuring the angle (2θ) and intensity of diffraction lines diffracted so as to satisfy the Bragg equation (nλ = 2dsinθ) on the lattice plane at the interval (d). is there. In the present invention, measurement was performed under the following conditions using CuKα rays.
Used measuring machine / Mach Science, full automatic X-ray diffractometer MXP18
X-ray tube / Cu
Voltage / 50KV
Tube current / 300mA
Scan method / 2θ / θ scan Scan speed / 4deg. / Min
Sampling interval / 0.020 deg.
Start angle (2θ) / 3deg.
Stop angle (2θ) / 60 deg.
Divergence slit / 0.5 deg.
Scattering slit / 0.5 deg.
Receiving slit / 0.3mm.
Uses curved monochromator

  The primary particle size of forsterite used in the present invention is preferably 0.05 μm or more and 0.50 μm or less. The effect of heat insulation described above becomes smaller as the primary particle size of forsterite is smaller. However, if the primary particle size is 0.05 μm or more, the heat insulation effect is more effectively exhibited. On the other hand, if the primary particle size of forsterite exceeds 0.50 μm, the forsterite cannot be retained on the surface of the toner base particles and the heat insulating effect is reduced. However, if the primary particle size is 0.50 μm or less as a result of investigation, It was found that stellite can be satisfactorily held on the surface of the toner base particles and exhibits a heat insulating effect.

  The primary particle size of forsterite was determined by measuring the major axis and minor axis of 100 particles from a photograph taken at a magnification of 50,000 with an electron microscope, and determining the average particle size.

Further, when the charging means of the electrostatic charge latent image carrier is a contact charging method in which a DC voltage superimposed on a direct current or an alternating current is applied by bringing the electrostatic charge latent image carrier into contact with a roller, blade, brush or the like. If a substance having a high dielectric constant exists between the charging member and the surface of the latent electrostatic image bearing member, the effective bias of that portion is lowered, and it is considered that charging failure occurs.
In the case of a non-contact charging means such as corona charging, if a substance having a high dielectric constant adheres to the wire of the charger, it is considered that the discharge of that portion is hindered and charging failure occurs.
In general, titanium oxide, alumina and magnesium oxide used as external additives have a high dielectric constant of about 10 to 100, whereas forsterite used in the present invention has a low dielectric constant of about 6. It is. Therefore, even if it adheres to the charging member, the influence on the charging of the latent electrostatic image bearing member can be reduced. For this reason as well, forsterite is preferred as the inorganic fine particles used in the present invention.

  The forsterite used in the toner of the present invention may be only one kind of forsterite or two or more kinds of forsterite having different physical properties such as particle diameter.

Although there is no restriction | limiting in particular about the manufacturing method of the forsterite used for this invention, For example, the manufacturing method currently disclosed by Unexamined-Japanese-Patent No. 2003-2640, Unexamined-Japanese-Patent No. 2003-327470, etc. can be used.
In the method for producing forsterite, it is preferable that the sintering temperature is 900 ° C. to 1000 ° C. and the sintering time is 1 hour to 5 hours. By appropriately adjusting the sintering temperature and the sintering time in this way, the forsterite is adjusted to a single phase, the particle size of the forsterite is controlled, and the peak intensity at a Bragg angle of 36.4 deg in CuKα characteristic X-ray diffraction. The ratio of the peak intensities of 26.5 deg and 42.9 deg is also controlled. The reason for this is not clear, but it is considered that the forsterite particle size is affected by the raw material SiO ₂ particle size. _The inventors consider that the _two particles are completely united (sintered) and cannot be crushed and the particle size becomes large. In addition, the inventors think that it is necessary to sinter at a low temperature for a long time because the surface is sintered before the reaction proceeds to the inside of the raw material at a high temperature, and only the surface has a forsterite structure. .

In the present invention, in order to improve developability and durability, the following inorganic fine particles can be further added to the toner base particles as long as the effects of the present application are not impaired. Examples of the inorganic fine particles include silicon, zinc, aluminum, titanium, cerium, cobalt, iron, zirconium, chromium, manganese, strontium, tin, and antimony oxides or composite oxides; barium sulfate, calcium carbonate, carbonic acid Metal salts such as magnesium and aluminum carbonate; clay minerals such as kaolin; phosphoric acid compounds such as apatite; silicon compounds such as silicon carbide and silicon nitride; and carbon powders such as carbon black and graphite.

  For the same purpose, the following organic particles and composite particles may be added to the toner base particles as long as the effects of the present application are not impaired. Resin particles such as polyamide resin particles, silicon resin particles, silicon rubber particles, urethane particles, melamine-formaldehyde particles, acrylic particles; rubbers, waxes, fatty acid compounds or resins, and inorganic particles of metals, metal oxides, and carbon black Composite particles comprising: Teflon (registered trademark), fluorine resin such as polyvinylidene fluoride; fluorine compound such as carbon fluoride; fatty acid metal salt such as zinc stearate; fatty acid derivative such as fatty acid ester; molybdenum sulfide, amino acid and amino acid Derivatives.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

<Forsterite Production Example 1>
The slurry of Mg (OH) ₂ powder and SiO ₂ powder (average primary particle diameter 12 nm) were weighed so as to be 2: 1 with MgO: SiO ₂ (molar ratio), MgO concentration 57.2 g / l, SiO ₂ concentration A slurry of 42.6 g / l and 150 l is used, and a sand grinder mill (Dyno mill: manufactured by Willy et Bacofen) uses 0.8 mmφ zirconia beads as the media, a media filling rate of 80%, and a liquid feeding speed of 4. Wet pulverization was performed under the conditions of 0 l / min and the number of slurry passes of 4 passes. The slurry was spray-dried with a spray dryer and fired at 980 ° C. for 3 hours in the air in an electric furnace. Thereafter, the fired product is slurried to 300 g / l, 50 l is sand grinder mill, 0.8 mmφ alumina silica-based beads are used as media, the media filling rate is 80%, and the liquid feeding speed is 5.6 l / The wet pulverization was performed under the condition of min and the number of slurry passes of 4 passes. The slurry was spray-dried with a spray dryer and pulverized with a sand mill to obtain forsterite powder. This is forsterite A.

<Forsterite Production Example 2>
In Production Example 1 of forsterite, the average primary particle size of the SiO ₂ powder used was 5
A forsterite powder was obtained in the same manner as in Forsterite Production Example 1 except that the thickness was changed to 0 nm. This is forsterite B.

<Forsterite Production Example 3>
In Forsterite Production Example 1, forsterite powder was obtained in the same manner as Forsterite Production Example 1 except that the number of slurry passes in the first wet grinding was changed to 7 passes. This is forsterite C.

<Forsterite Production Example 4>
In Forsterite Production Example 1, the average primary particle size of the SiO ₂ powder used is 1
A forsterite powder was obtained in the same manner as in Forsterite Production Example 1 except that the thickness was changed to 00 nm. This is forsterite D.

<Forsterite Production Example 5>
The following solutions were prepared.
(1) Magnesium nitrate aqueous solution: Prepared by dissolving 5.12 g of magnesium nitrate hexahydrate in 1 l of water.
(2) Ethyl silicate aqueous solution: prepared by adding 4.16 g of ethyl silicate and 0.63 g of nitric acid (concentration 60 mass%) to 800 ml of water and refluxing for 12 hours.

  The magnesium nitrate aqueous solution and the ethyl silicate aqueous solution were mixed at a ratio of 2: 1 to prepare a test solution. The prepared test solution was sprayed to form a mist, which was fired at 920 ° C. to obtain a forsterite powder. This is forsterite E.

<Forsterite Production Example 6>
In Forsterite Production Example 5, forsterite powder was obtained in the same manner as Forsterite Production Example 5 except that the firing temperature was changed to 1020 ° C. This is forsterite F.

<Forsterite Production Example 7>
In Forsterite Production Example 5, forsterite powder was obtained in the same manner as Forsterite Production Example 5 except that the firing temperature was changed to 870 ° C. This is forsterite G.

<Forsterite Production Example 8>
Forsterite A is placed in a sealed high-speed stirrer and stirred while purging with nitrogen. A treatment agent obtained by diluting 20 parts by mass of dimethyl silicone oil with methyl ethyl ketone (MEK) 10 times with respect to 100 parts by mass of forsterite A is sprayed into the stirrer. After spraying the entire amount of the treatment agent, the temperature inside the stirrer was raised to 180 ° C. while stirring and stirred for 3 hours. While stirring, the temperature in the stirrer was returned to room temperature, and then pulverized with a pin mill to obtain forsterite powder. This is forsterite H.

<Production Example 9 of Forsterite>
A forsterite powder was obtained in the same manner as in forsterite production example 8 except that forsterite F was used instead of forsterite A in forsterite production example 8. This is forsterite I.

  Table 1 shows the physical property values of each forsterite.

The degree of hydrophobicity was measured by the following method.
Take 1 g of forsterite in a 200 ml separatory funnel and add 100 ml of ion-exchanged water. A separatory funnel is set on a shaker (turbula shaker mixer T2C type: manufactured by Willy A. Bochofen Manufacturing Engineers) and dispersed at 90 rpm for 10 minutes. Thereafter, the mixture is allowed to stand for 10 minutes, and then 20 to 30 ml is extracted, and then taken into 10 mm cells. The turbidity of the water layer is measured with a spectrophotometer UV-210 (Shimadzu Corporation) using ion-exchanged water as a blank. The reading at a wavelength of 500 nm is defined as the degree of hydrophobicity.

<Example of production of toner base particles>
100 parts by mass of styrene acrylic resin (styrene-butyl acrylate copolymer ratio = 60: 40)
(Weight average molecular weight = 250,000, Tg = 58 ° C.)
Magnetic substance (EPT-1000 (manufactured by Toda Kogyo)) 80 parts by mass of salicylic acid metal compound 3 parts by mass (aluminum compound of 3,5-di-tert-butylsalicylic acid)
Paraffin wax (melting point = 95 ° C) 2.5 parts by mass The above was mixed using a Henschel mixer, melt-kneaded with a twin-screw extruder kneader, coarsely pulverized with a hammer mill, and finely pulverized with a jet mill. Mechanical pulverization was performed and further classified to obtain toner base particles having a weight average particle diameter of 6.3 μm.

<Example 1>
1 part by mass of hydrophobic silica (average particle size of primary particles 9 nm) treated with 15 parts by mass of hexamethyldisilazane per 100 parts by mass of silica and 100 parts by mass of toner base particles, and forsterite A 2 parts by mass with respect to 100 parts by mass of the base particles are externally added to the toner base particles with a Henschel mixer FM10B (manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 66 s ⁻¹ and a time of 5 minutes. got a.

The toner a was evaluated using a digital copying machine (Canon: GP405). GP
Reference numeral 405 denotes a digital copying machine using a laser beam. The outline of the apparatus is that an organic photoreceptor is used as an electrostatic charge latent image carrier, a charging roller is provided as a charging means for the electrostatic latent image carrier, and a cleaning member made of a non-woven pad member is used for cleaning the charging roller. Equipped with a one-component developing unit that employs a one-component jumping development method in which the toner on the developer carrier and the electrostatic latent image carrier are not in contact with each other as a developing unit, a charging roller as a transfer unit, and blade cleaning Means and pre-charging exposure means. The electrostatic charge latent image carrier charger, the cleaning means, and the electrostatic latent image carrier are an integral unit. The process speed is 210 mm / s, and A4 size allows 40 continuous copies per minute.

  The evaluation mode and the evaluation method were performed as follows.

(Evaluation mode 1)
Using the chart shown in FIG. 1, continuous copying of 20,000 sheets in A4 size is performed. The evaluation environment is 20
It is performed individually in each environment of ° C / 5% RH, 23 ° C / 60% RH, and 35 ° C / 90% RH.

(Evaluation mode 2)
With the cleaning member of the charging roller removed, continuous copying of 20,000 sheets in A4 size is performed using the chart shown in FIG. 1 in a 35 ° C./90% RH environment. The latent electrostatic image bearing member on which continuous copying of 20,000 sheets was completed was aged (acclimated) in a 20 ° C./5% RH environment for 24 hours, and then the density measured by a reflection densitometer RD918 (manufactured by Macbeth) was Sampling (copying) with a halftone chart of 0.2.

(Evaluation mode 3)
Using the chart shown in FIG. 1 in a 35 ° C./90% RH environment, continuous copying of 20,000 sheets in A4 size is performed. After the continuous copying of 20,000 sheets, the environment is changed to 23 ° C / 60% RH,
After aging for 24 hours, continuous copying of 20,000 sheets in A4 size is performed again using the chart shown in FIG. Similarly, after 20,000 continuous copies have been completed in a 35 ° C / 90% RH environment,
The environment is set to 20 ° C./5% RH and after aging for 24 hours, 20,000 continuous copies are performed again.

(Evaluation Method 1: Image Density Reduction)
The image density of the solid black portion of the 100th and 20,000th samples in the evaluation mode 1 is measured (each 9 points average), and the difference is obtained. Density measurement was performed with a reflection densitometer RD918 (manufactured by Macbeth). The ranking of evaluation was performed as follows.
A: Density difference less than 0.05 B: Density difference between 0.05 and less than 0.1 C: Density difference between 0.1 and less than 0.15 D: Density difference between 0.15 and less than 0.20 E: Density difference between 0.20 and more

(Evaluation method 2: Cover)
The reflectance of the solid white portion of the 100th and 20,000th samples in evaluation mode 1 is measured (each 9 points average), and the difference is obtained. The reflectance was measured with TC-6DS (manufactured by Tokyo Denshoku). In addition, measure the reflectance of unused paper in the same way. The ranking of evaluation was performed as follows.
A: Reflectance difference of less than 0.5 B: Reflectance difference of 0.5 to less than 1.0 C: Reflectance difference of 1.0 to less than 1.5 D: Reflectance difference of 1.5 to less than 2.0 E: Reflectance difference of 2.0 or more

(Evaluation method 3: Toner scattering)
At the end of evaluation mode 1, the toner (scattered toner) adhering to the bottom of the developing sleeve of the one-component developing device frame is collected with a tape and pasted on a white paper, and the density is measured with a reflection densitometer RD918 (manufactured by Macbeth). The density obtained by subtracting the blank paper was determined. The ranking of evaluation was performed as follows.
A: Concentration less than 0.05 B: Concentration from 0.05 to less than 0.1 C: Concentration from 0.1 to less than 0.15 D: Concentration from 0.15 to less than 0.20 E: Concentration from 0.20 or more

(Evaluation Method 4: Charging Roller Dirt)
On the halftone sample in evaluation mode 2, the density on the charging roller at the position corresponding to each of the solid black portion and solid white portion of the chart used for continuous copying of 20,000 sheets was measured and the difference was obtained. Density measurement was performed with a reflection densitometer RD918 (manufactured by Macbeth). The ranking of evaluation was performed as follows.
A: Density difference less than 0.05 B: Density difference between 0.05 and less than 0.1 C: Density difference between 0.1 and less than 0.15 D: Density difference between 0.15 and less than 0.20 E: Density difference between 0.20 and more

(Evaluation Method 5: Filming)
After the evaluation mode 3 is completed, the surface of the latent electrostatic image bearing member is observed with a digital high-vision microscope VQ-7000 (manufactured by Keyence Corporation) (magnification 300 times). A portion where filming occurs in the visual field is marked, an area is obtained, and an area ratio where filming occurs in the visual field is obtained. This was observed over 20 fields on the entire surface of the electrostatic latent image bearing member, and the average value was defined as the filming occurrence rate. The ranking of evaluation was performed as follows.
A: Filming occurrence rate less than 1% B: Filming occurrence rate 1% or more and less than 5% C: Filming occurrence rate 5% or more and less than 10% D: Filming occurrence rate 10% or more and less than 15% E: Filming occurrence More than 15%

  The evaluation results are shown in Table 2. In the evaluation, the A to C levels are acceptable levels, and the D and E levels are impractical levels.

<Example 2 to Example 9>
In Example 1, toners b, c, d, e, f, g, h, and i were obtained in the same manner except that forsterite B to I were used instead of forsterite A, respectively. The toner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Example 10>
A toner j was obtained in the same manner as in Example 1 except that forsterite A was changed to 0.04 parts by mass. The toner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Example 11>
Toner k was obtained in the same manner as in Example 1 except that forsterite A was changed to 4 parts by mass. The toner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Example 12>
In Example 1, the same procedure was followed except that 6 parts by mass of forsterite A was added.
Got. The toner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative Example 1>
100 parts by mass of silica and 15 parts by mass of hexamethyldisilazane surface-treated with hydrophobic silica (average particle size of primary particles 9 nm), 1 part by mass is rotated by Henschel mixer FM10B with respect to 100 parts by mass of toner base particles. The toner m was obtained by external addition under conditions of number: 66 s ⁻¹ , time: 5 minutes. The toner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative example 2>
Hydrophobic silica (average particle size 9 nm of primary particles) surface-treated with 15 parts by mass of hexamethyldisilazane on 100 parts by mass of silica, 1 part by mass and magnesium oxide (product name: Micromag A toner n was obtained by externally adding 2 parts by mass of Kyowa Chemical Co., Ltd. with a Henschel mixer FM10B under the conditions of a rotational speed of 66 s ⁻¹ and a time of 5 minutes. The toner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

<Comparative Example 3>
Hydrophobic silica (average particle size of primary particles 9 nm) surface-treated with 15 parts by mass of hexamethyldisilazane on 100 parts by mass of silica, 1 part by mass and titanium oxide (product name: JR) 2 parts by mass) were externally added with a Henschel mixer FM10B under the conditions of a rotational speed of 66 s ⁻¹ and a time of 5 minutes to obtain a toner o. The toner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

It is a chart used for evaluation.

Claims (6)

The toner base particles containing at least a binder resin and a magnetic material, a magnetic toner comprising an inorganic fine particles,
A magnetic toner, wherein at least one of the inorganic fine particles is forsterite. The ratio of the peak intensity of 26.5 deg and 42.9 deg to the peak intensity of Bragg angle (2θ ± 0.2 deg) of 36.4 deg in CuKα characteristic X-ray diffraction of the forsterite is 0.1 or less. The magnetic toner according to claim 1. The magnetic toner according to claim 1, wherein the forsterite has a primary particle size of 0.05 μm or more and 0.50 μm or less. The magnetic toner according to claim 1, wherein the surface of the forsterite has been subjected to a hydrophobic treatment. The ratio of the peak intensity of 26.5 deg and 42.9 deg to the peak intensity of Bragg angle (2θ ± 0.2 deg) of 36.4 deg in CuKα characteristic X-ray diffraction of the forsterite is 0.001 or less. The magnetic toner according to claim 1, wherein the toner is a magnetic toner. 6. The magnetic toner according to claim 1, wherein the forsterite is added in an amount of 0.05 to 5.00 parts by mass with respect to 100 parts by mass of the toner base particles. .

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