JP2003177571A - Toner and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner having a narrow particle size distribution, capable of keeping the particle shape essentially spherical, capable of reliably forming recesses in the particle surfaces, excellent in suitability to cleaning with a cleaning blade and excellent also in an initial image and a permanent image after continuous printing and to provide a method for manufacturing the toner. <P>SOLUTION: A polymerizable monomer composition comprising at least a polymerizable monomer, a colorant and metal oxide particles is dispersed in an aqueous medium containing a slightly water-soluble metal hydroxide, toner particles are obtained by polymerizing the composition and metal oxide particles exposed to the surfaces of the toner particles are removed by a chemical method to manufacture the objective toner. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner, and more specifically, a method for producing a toner by a polymerization method for developing an electrostatic latent image formed by an electrophotographic method, an electrostatic recording method or the like. It is about the method.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, an electrostatic latent image formed on a photoconductor is first developed with toner. Next, the formed toner image is transferred onto a transfer material such as paper, if necessary,
It is fixed by various methods such as heating, pressurization, and solvent vapor. As the toner used in the apparatus, a pulverized toner produced by melting and mixing a thermoplastic resin containing a colorant, a charge control agent, etc., and then pulverizing and classifying the resin is the mainstream. In recent years, in the image forming apparatus, higher resolution of images and higher speed of image formation have been demanded, but it is difficult to meet these demands because pulverized toner has a wide particle size distribution of obtained particles. Met. In order to overcome the problem of the pulverized toner, a polymerized toner produced by polymerizing a polymerizable monomer composition containing a colorant and a polymerizable monomer has been proposed. The polymerized toner can be made to have a small particle size by adjusting the polymerization conditions, and the particle size distribution can be narrowed. Therefore, the polymerized toner satisfies the requirement of a toner having excellent melting characteristics accompanying the speeding up of the printer. .

Since the polymerized toner is spherical, it has good fluidity and excellent transferability to a transfer material, but on the other hand, it may have insufficient cleaning performance. In order to solve this, JP-A-62-266557
The publication discloses a method for producing an amorphous toner in which a polymerizable monomer containing poorly water-soluble inorganic fine particles is polymerized, and the inorganic fine particles exposed on the surface of the obtained toner are removed by a chemical method. ing. However, JP-A-62-26
As a result of the present inventors' investigation according to the production method described in Japanese Patent No. 6557, when poorly water-soluble inorganic fine particles such as zinc carbonate and calcium carbonate are used, these particles have stronger hydrophilicity than the polymerizable monomer. Therefore, most of them are present in the aqueous dispersion medium without being included in the polymerizable monomer, and even if polymerization is performed in this state, the hardly water-soluble inorganic fine particles present on the formed toner surface are Due to the small amount, it may not be possible to obtain an irregular toner. Further, if the silica particles described in the examples are used as a dispersion stabilizer, the particle size distribution of the toner may be widened and fog may easily occur.

Further, in Japanese Patent Application Laid-Open No. 7-114212, it is difficult to increase the affinity for a polymerizable monomer by subjecting the polymerizable monomer and an aluminum coupling agent to a hydrophobic treatment with a coupling agent. A monomer phase containing water-soluble inorganic fine particles, in a state of being suspended and dispersed in an aqueous dispersion medium in a droplet form, after polymerizing a polymerizable monomer to obtain toner particles, the surface of the toner particles A method for producing an electrophotographic toner by chemically removing inorganic fine particles to form recesses is disclosed. However, this method is difficult to control the degree of affinity to the polymerizable monomer, and if the affinity is high,
In some cases, the poorly water-soluble inorganic fine particles may be buried inside the toner particles to produce a toner having concave portions,
It was found that when the coupling treatment described in the examples is carried out, the unreacted coupling agent affects the physical properties of the toner and the image characteristics deteriorate. On the other hand, if the affinity is too low, then the method disclosed in JP-A-6-6
As described in JP-A-2-266557, since the inorganic fine particles are not contained in the polymerizable monomer and most of them are present in the aqueous dispersion medium, it becomes impossible to form recesses in the toner obtained by the polymerization. There was an occasion. Further, when the tricalcium phosphate described in the examples is used as the dispersion stabilizer, the particle size distribution of the toner is widened, and fog is likely to occur.

[0005]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to have a narrow particle size distribution, to keep the particle shape basically spherical, and to reliably form recesses on the particle surface. It is an object of the present invention to provide a toner and a method for producing the toner, which have excellent cleaning properties with a cleaning blade and are excellent in initial images and durable images after continuous printing.

[0006]

Thus, according to the present invention, (1) a polymerizable monomer composition containing at least a polymerizable monomer, a colorant and metal oxide particles is added to a slightly water-soluble metal water. A method for producing a toner, wherein toner particles are obtained by dispersing in an aqueous medium containing an oxide and then polymerizing, and the metal oxide particles exposed on the surface of the toner particles are removed by a chemical method, (2) Poorly water-soluble metal hydroxide and metal oxide particles are composed of the same metal element (1)
A method for producing the toner described above. (3) Volume average particle size (Dv)
Is 1 to 10 μm, volume average particle diameter and number average particle diameter (Dp)
A toner having a particle size distribution (Dv / Dp) of 1.2 or less, an average circularity of 0.90 to 0.99, and toner particles having concave portions on the particle surface and an external additive, Will be provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The polymerizable monomer composition used in the method for producing a toner of the present invention contains at least a polymerizable monomer, a colorant and metal oxide particles.

Examples of the polymerizable monomer include monovinyl monomer, crosslinkable monomer, macromonomer and the like. Specific examples of the monovinyl monomer include aromatic vinyl monomers such as styrene, vinyltoluene, and α-methylstyrene; (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, ( Propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, (meth) acrylamide, etc. (Meth) acrylic acid derivatives of the above; monoolefin monomers such as ethylene, propylene and butylene; and the like. The monovinyl monomer may be used alone or in combination of a plurality of monomers. Among these monovinyl monomers, it is preferable to use the aromatic vinyl monomer alone or the aromatic vinyl monomer and the (meth) acrylic acid derivative in combination.

The use of a crosslinkable monomer and a crosslinkable polymer together with a monovinyl monomer is effective for improving hot offset. The crosslinkable monomer is a monomer having two or more polymerizable carbon-carbon unsaturated double bonds. Specifically, aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and their derivatives; diethylenically unsaturated carboxylic acid esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; N,
Examples thereof include compounds having two vinyl groups such as N-divinylaniline; divinyl ether; and compounds having three or more vinyl groups such as pentaerythritol triallyl ether and trimethylolpropane triacrylate. The crosslinkable polymer is a polymer having two or more vinyl groups in the molecule, and specifically, it is 2 in the molecule.
An ester obtained from a polymer having at least one hydroxyl group and an unsaturated carboxylic acid monomer such as acrylic acid or methacrylic acid can be mentioned. These crosslinkable monomers and crosslinkable polymers may be used alone or in combination of two or more. The amount used is usually 10 parts by weight or less, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the monovinyl monomer.

Further, it is preferable to use a macromonomer together with the monovinyl monomer because a good balance between storability and low-temperature fixability can be obtained. The macromonomer has a vinyl polymerizable functional group at the end of the molecular chain, and is usually an oligomer or polymer having a number average molecular weight of 1,000 to 30,000. If the number average molecular weight is too small, the surface portion of the polymer particles becomes soft and the storage stability is deteriorated. On the other hand, if the number average molecular weight is too large, the meltability of the macromonomer deteriorates and the fixability and storability deteriorate. Examples of the vinyl polymerizable functional group at the end of the macromonomer molecular chain include an acryloyl group and a methacryloyl group, and a methacryloyl group is preferable from the viewpoint of ease of copolymerization.

The macromonomer preferably has a glass transition temperature higher than the glass transition temperature of the polymer obtained by polymerizing the monovinyl monomer. Specific examples of the macromonomer that can be used in the present invention include polymers obtained by polymerizing styrene, styrene derivatives, methacrylic acid esters, acrylic acid esters, acrylonitrile, methacrylonitrile, etc., alone or in combination of two or more kinds,
Examples thereof include macromonomers having a polysiloxane skeleton, and among them, hydrophilic polymers, particularly polymers obtained by polymerizing methacrylic acid esters or acrylic acid esters alone or in combination thereof are preferable. If a macromonomer is used, its amount is
It is usually 0.0 with respect to 100 parts by weight of the monovinyl monomer.
It is 1 to 10 parts by weight, preferably 0.03 to 5 parts by weight, and more preferably 0.05 to 1 part by weight. If the amount of macromonomer is small, the storage stability will not be improved. If the amount of macromonomer becomes extremely large, the fixability will decrease.

As the colorant, carbon black, titanium black, magnetic powder, oil black, titanium white, or any pigment and / or dye can be used. Black carbon black has a primary particle size of 20-
Those having a thickness of 40 nm are preferably used. If it is less than 20 nm, the carbon black aggregates and is not uniformly dispersed in the toner, which may result in a toner with a large amount of fog. On the other hand, when it is larger than 40 nm, a large amount of polyvalent aromatic hydrocarbon compounds such as benzpyrene produced during the production of carbon black may remain in the toner, which may cause environmental safety problems.

To obtain a full color toner, yellow colorants, magenta colorants and cyan colorants are usually used. As the yellow colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17,
62, 65, 73, 83, 90, 93, 97, 120,
138, 155, 180, 181, 185 and 186
Etc. As the magenta colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Red 48, 57, 58, 60,
63, 64, 68, 81, 83, 87, 88, 89, 9
0, 112, 114, 122, 123, 144, 14
6, 149, 163, 170, 184, 185, 18
7, 202, 206, 207, 209, 251, C.I.
I. Pigment Violet 19 and the like. As the cyan colorant, a copper phthalocyanine compound and its derivative, an anthraquinone compound, etc. can be used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 1
5: 1, 15: 2, 15: 3, 15: 4, 16, 17,
And 60 and the like. The amount of such a colorant is usually 1 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

As the metal oxide particles, those which can be removed by a chemical method after polymerization, for example, those which can be dissolved with an acid or an alkali are used. Specific examples of the metal oxide particles include magnesium oxide, aluminum oxide, iron oxide, and the like, but when using a sparingly water-soluble metal hydroxide as a dispersion stabilizer described later, a sparingly water-soluble metal is used. The metal element forming the hydroxide and the metal element forming the metal oxide particles are preferably of the same type, of which magnesium oxide is particularly preferable. The particle size is usually 0.1
It is 20 μm, preferably 0.5 to 10 μm. The addition amount is usually 0.1 with respect to 100 parts by weight of the polymerizable monomer.
-30 parts by weight, preferably 0.5-20 parts by weight.

In addition to the above-mentioned polymerizable monomer, colorant and metal oxide particles, a charge control agent, a release agent and the like may be added to the polymerizable monomer composition. As the charge control agent, a charge control agent conventionally used for toner can be used. For example, Bontron N01 (manufactured by Orient Chemical Industry Co., Ltd.), Nigrosine Base EX (manufactured by Orient Chemical Industry Co., Ltd.), Spiron Black TRH (manufactured by Hodogaya Chemical Co., Ltd.), T-77 (manufactured by Hodogaya Chemical Co., Ltd.), Bontron S-34. (Manufactured by Orient Chemical Industry Co., Ltd.), Bontron E-
81 (Orient Chemical Co., Ltd.), Bontron E-84
(Made by Orient Chemical Industry), COPY CHARGE
NX (Clariant), COPY CHARGE
Charge control agents such as NEG (manufactured by Clariant Co., Ltd.) may be mentioned, and JP-A No. 63-60458 and JP-A No. 3-6043.
-175456, JP-A-3-243954, JP-A-11-15192, etc., a quaternary ammonium (salt) group-containing copolymer produced according to the description, JP-A-1-217464, A sulfonic acid (salt) group-containing copolymer produced according to the description in, for example, Kaihei 3-15858 can also be used as a charge control agent (charge control resin).

Among these, it is preferable to use the charge control resin. The charge control resin is preferable because it has high compatibility with the binder resin, is colorless, and can provide a toner having stable chargeability even in continuous color printing at high speed. The glass transition temperature of the charge control resin is usually 40 to 8
0 ° C, preferably 45 to 75 ° C, more preferably 45
~ 70 ° C. If it is lower than this range, the storage stability of the toner deteriorates, and conversely if it is higher, the fixing property may deteriorate. The amount of the charge control agent is usually 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer.

Examples of the release agent include low molecular weight polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; plant-based natural waxes such as candelilla, carnauba, rice, and wax; paraffin, microcrystalline, Petroleum waxes such as petrolactam; synthetic waxes such as Fischer-Tropsch wax; and polyfunctional ester compounds such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, and dipentaerythritol hexamyristate. These can be used alone or in combination of two or more.

Of these, synthetic waxes (particularly Fischer-Tropsch wax), petroleum waxes, polyfunctional ester compounds and the like are preferable. Among the polyfunctional ester compounds, in the DSC curve measured by a differential scanning calorimeter, the endothermic peak temperature at the time of temperature rise is 30 to 120 ° C,
Preferably 40 to 100 ° C., more preferably 50 to 80
A polyvalent ester compound such as a pentaerythritol ester having a temperature range of 50 ° C. or a dipentaerythritol ester having an endothermic peak temperature of 50 to 80 ° C. is particularly preferable in terms of fixing-releasing balance as a toner,
Among them, styrene 1 has a molecular weight of 1000 or more.
It is more preferable to dissolve 5 parts by weight or more at 25 ° C. with respect to 00 parts by weight and to have an acid value of 10 mg / KOH or less, since a remarkable effect in lowering the fixing temperature is exhibited. Endothermic peak temperature is AST
It is the value measured by MD3418-82. The amount of the release agent is 100 parts by weight of the polymerizable monomer,
Usually, 0.5 to 50 parts by weight, preferably 1 to 20 parts by weight is used.

Next, the polymerizable monomer composition is added to an aqueous medium containing a sparingly water-soluble hydroxide, dispersed with a usual stirrer or a homogenizer, and then polymerized to obtain toner particles. obtain. If necessary, an aggregating agent may be added to the toner particles produced by the polymerization so that the particles are associated with each other.
The polymerization temperature is usually 40 to 120 ° C., preferably 50 to 120 ° C.
It is 100 ° C.

Examples of the poorly water-soluble metal hydroxide include aluminum hydroxide, magnesium hydroxide, ferric hydroxide and the like. The dispersion stabilizer containing a colloid of sparingly water-soluble metal hydroxide is not limited by its production method,
A colloid of a poorly water-soluble metal hydroxide obtained by adjusting the pH of an aqueous solution of a water-soluble polyvalent metal compound to 7 or more, particularly by a reaction between a water-soluble polyvalent metal compound and an alkali metal hydroxide in an aqueous phase. It is preferable to use a hardly water-soluble colloid of a metal hydroxide that is produced. As the poorly water-soluble metal hydroxide, it is preferable to use the same metal as the metal oxide particles as described above, and magnesium hydroxide is particularly preferable.

The slightly water-soluble metal hydroxide colloid has a number particle size distribution D50 (50% cumulative value of the number particle size distribution) of 0.
D90 (90% cumulative value of number particle size distribution) at 5 μm or less
Is preferably 1 μm or less. If the particle size of the colloid becomes large, the stability of polymerization will deteriorate and the storage stability of the toner will also deteriorate.

The dispersion stabilizer is usually used in a proportion of 0.1 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer. If this ratio is less than 0.1 part by weight, it is difficult to obtain sufficient polymerization stability, and polymer aggregates are easily generated. On the other hand, if it exceeds 20 parts by weight, the toner particle size after polymerization becomes too fine, which is not practical.

As the polymerization initiator, a persulfate such as potassium persulfate; 4,4'-azobis (4-cyanovaleric acid),
2,2'-azobis (2-methyl-N- (2-hydroxyethyl) propionamide, 2,2'-azobis (2
-Methyl-N- (1,1'-bis (hydroxymethyl)
Ethyl) propioamide, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (2,2
Azo compounds such as 4-dimethylvaleronitrile) and 2,2′-azobisisobutyronitrile; lauroyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy- 2-ethylhexanoate, t-butylperoxypivalate, di-isopropylperoxydicarbonate, 1,1,3,3-tetramethylbutylperoxy-
Examples thereof include peroxides such as 2-ethylhexanoate and t-butylperoxyisobutyrate.

Among these, it is particularly preferable to select an oil-soluble polymerization initiator that is soluble in the polymerizable monomer used, and a water-soluble polymerization initiator can be used in combination therewith if necessary. . The polymerization initiator is a polymerizable monomer 10
0.1 to 20 parts by weight, preferably 0.3 to 15 parts by weight, and more preferably 0.5 to 10 parts by weight, relative to 0 parts by weight.
Use parts by weight. The polymerization initiator can be added in advance to the polymerizable monomer composition, but in the case of suspension polymerization, it can also be added directly to the suspension after the granulation step or during the polymerization reaction.

Further, it is preferable to add a molecular weight modifier during the polymerization. As the molecular weight modifier, for example,
t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, 2,2,4,6,6-
Mention may be made of mercaptans such as pentamethylheptane-4-thiol. These molecular weight modifiers can be added before the start of the polymerization or during the polymerization.
The molecular weight modifier is 100 parts by weight of the polymerizable monomer,
Usually, it is used in a proportion of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight.

In the production method of the present invention, so-called core-shell type (also referred to as capsule type) toner particles can be obtained by combining two different polymers inside (core layer) and outside (shell layer) of the particles. preferable. In the core-shell type toner particles, by encapsulating a low softening point substance inside (core layer) with a substance having a higher softening point, it is possible to balance the lowering of the fixing temperature and the prevention of aggregation during storage. It is preferable because it is possible.

The core-shell type toner particles are continuously polymerized by adding a polymerizable monomer for forming a shell (polymerizable monomer for shell) to the reaction system after the polymerization of the core particles. It can be manufactured by The polymerizable monomer for shell may be added to the reaction system all at once, or may be added continuously or intermittently using a pump such as a plunger pump.

As the shell polymerizable monomer, a monomer such as styrene, acrylonitrile or methyl methacrylate which forms a polymer having a glass transition temperature of higher than 80 ° C. may be used alone or in combination of two or more kinds. be able to.

When the polymerizable monomer for shell is added, it is preferable to add a water-soluble radical initiator because it facilitates obtaining core-shell type toner particles. When the water-soluble radical initiator is added during the addition of the shell polymerizable monomer, the water-soluble radical initiator enters near the outer surface of the core particle to which the shell polymerizable monomer has migrated, and the core particle surface It is considered that the polymer (shell) is easily formed in the above.

As the water-soluble radical initiator, persulfates such as potassium persulfate and ammonium persulfate; 4,4'-
Azobis (4-cyanovaleric acid), 2,2'-azobis (2-methyl-N- (2-hydroxyethyl) propionamide, 2,2'-azobis (2-methyl-N-)
Azo initiators such as (1,1′-bis (hydroxymethyl) ethyl) propioamide and 2,2′-azobis (2-amidinopropane) dihydrochloride; oil-soluble initiators such as cumene peroxide and redox catalysts Combinations; and the like. The amount of the water-soluble radical initiator is usually 1 to 50% by weight, preferably 2 to 20% by weight, based on 100 parts by weight of the shell monomer.

The metal oxide particles existing on the surface of the toner particles obtained by the polymerization are removed by a chemical method. For example, it is treated with an acid or an alkali to dissolve the metal oxide particles and then filtered to remove them from the toner particles. If necessary, after repeating acid or alkali treatment, the toner is washed with ion-exchanged water or water diluted with an aqueous medium used for polymerization, if necessary, with water, filtered, and dried to obtain a toner. obtain.

By the method for producing a toner of the present invention, a toner having a volume average particle diameter (dv) of usually 1 to 10 μm, preferably 3 to 8 μm can be obtained. In addition, the particle size distribution, that is, the ratio of the volume average particle size to the number average particle size (dp) (dv /
dp) is usually 1.7 or less, preferably 1.5 or less,
It is more preferably 1.3 or less, and particularly preferably 1.2 or less. The circularity of toner particles is usually 0.
It is 8 to 1.00, preferably 0.85 to 0.99, and more preferably 0.90 to 0.99. This circularity is
It is a value obtained by a flow type particle analyzer.

If necessary, the toner produced by the method of the present invention may be mixed with an external additive to obtain a developer. Examples of the external additive include inorganic particles and organic resin particles. These particles added as an external additive have a smaller average particle size than the toner particles. For example, as the inorganic particles, silicon dioxide, aluminum oxide, titanium oxide,
Examples thereof include zinc oxide, tin oxide, barium titanate, and strontium titanate. As the organic resin particles, methacrylic acid ester polymer particles, acrylic acid ester polymer particles, styrene-methacrylic acid ester copolymer particles, styrene- Examples thereof include acrylic acid ester copolymer particles, core-shell type particles in which the core is a methacrylic acid ester polymer and the shell is a styrene polymer.
Of these, silicon dioxide particles and titanium oxide particles are preferable, and particles whose surface is hydrophobized are preferable,
Hydrophobized silicon dioxide particles are particularly preferred. The amount of the external additive is not particularly limited, but is usually 0.1 to 6 parts by weight with respect to 100 parts by weight of the toner. The attachment of the external additive is usually carried out by placing the external additive and the toner in a mixer such as a Henschel mixer and stirring the mixture.

[0034]

EXAMPLES The production method of the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples. Parts and% are based on weight unless otherwise specified. The methods for measuring physical properties in Examples and Comparative Examples are as follows. (1) Volume average particle diameter Toner volume average particle diameter (dv) and particle diameter distribution (dv / d)
p) is a Multisizer (Beckman Coulter)
It was measured by. The measurement with this Multisizer was performed under the conditions of an aperture diameter: 100 μm, a medium: Isoton II, a concentration of 10%, and the number of measured particles: 100,000. (2) Circularity The average circularity is the flow type particle image analyzer FPIA-210.
0 (manufactured by Sysmex Corporation), 1.5 μm to 15 μm
It was measured in the range of 0 μm.

(3) Three types of sieves having fluidity openings of 150 μm, 75 μm and 45 μm are stacked in this order from the top, and 4 g of the developer to be measured is precisely weighed and placed on the top sieve. Then, the three types of sieves thus piled up were vibrated for 15 seconds under the condition of a vibration strength of 4 using a powder measuring machine (manufactured by Hosokawa Micron Co., Ltd .; trade name "Powder Tester"), and then remained on each sieve. Measure the weight of the developer. The liquidity value is calculated by putting each measured value into the following equations and. One sample was measured three times, and the average value was calculated. Calculation formula: a = (weight of developer remaining on 150 μm sieve (g)) / 4
g × 100 b = (weight of developer remaining on 75 μm sieve (g)) / 4 g
× 100 × 0.6 c = (weight of developer remaining on 45 μm sieve (g)) / 4 g
× 100 × 0.2 Fluidity (%) = 100− (a + b + c)

(4) Cleanability and image evaluation Commercially available non-magnetic one-component developing system printer (24-sheet machine)
Was modified, a cleaning blade was attached, copy paper was set on this as a transfer material, and the developer to be evaluated was put in the developing device of this printer.
0 sheets were continuously printed. Regarding the clinability,
The photoreceptor and the charging roll were observed every 1,000 sheets, and the number of sheets where black streaks were generated due to poor cleaning was counted. In addition, regarding image evaluation, at the beginning of printing and 20,000
The image of the transfer material after printing 0 sheets was visually observed and evaluated according to the following criteria. ◯: The image density is high and no stain is observed on the transfer material. Δ: The image density is low, but no stain is observed on the transfer material. □: The image density was low and stains were observed on the transfer material.

(Example 1) 80.5 parts of styrene and n
-Polymer methacrylic acid ester macromonomer composed of 19.5 parts of butyl acrylate, polymethacrylic acid ester macromonomer (trade name "AA6", manufactured by Toagosei Co., Ltd., Tg = 94)
C) 0.3 part, divinylbenzene 0.5 part, t-dodecyl mercaptan 1.2 part, carbon black (manufactured by Mitsubishi Chemical Corporation, trade name "# 25B") 7 parts, charge control resin (manufactured by Fujikura Kasei Co., One copy of the product name "FCA-1001-NS"
Wet crushing using a media type wet crusher,
Magnesium oxide having an average particle size of 2 μm and a specific surface area of 1.5 m ² / g (Kyowa Chemical Co., Ltd., trade name “Pyrokissma 520
1 ") was added to obtain 10 parts of a polymerizable monomer composition for core. On the other hand, 1 part of magnesium chloride is added to 250 parts of ion-exchanged water.
An aqueous solution prepared by dissolving 6.2 parts of sodium hydroxide in 50 parts of ion-exchanged water was gradually added to an aqueous solution prepared by dissolving 0.2 parts under stirring to prepare a magnesium hydroxide colloidal dispersion. The particle size distribution of the produced colloid is SALD
When measured with a particle size distribution measuring device (manufactured by Shimadzu Corporation),
D50 (50% cumulative value of number particle size distribution) is 0.
At 35 μm, D90 (90% cumulative value of number particle size distribution) was 0.62 μm. On the other hand, methyl methacrylate 2
Parts and 65 parts of water were finely dispersed by an ultrasonic emulsifying machine to obtain an aqueous dispersion of the polymerizable monomer for shell. D90 of the droplets of the polymerizable monomer for shell was 1.6 μm.

The polymerizable monomer composition for core was added to the magnesium hydroxide colloidal dispersion obtained above (amount of colloid 4.0 parts) and stirred until the liquid droplets became stable. After adding 6 parts of butyl peroxy-isobutyrate (trade name "Perbutyl IB" manufactured by NOF CORPORATION),
Next, an Ebara Milder (trade name: MDN303V, manufactured by Ebara Corporation) rotating at 15,000 rpm was passed for a total residence time of 3 seconds, and the passed dispersion was jetted into the original stirring tank through an inner nozzle. The droplets of the monomer composition were granulated by circulating back at a speed of 0.5 m / s. The tip of the inner nozzle was adjusted so as to be located 50 mm below the surface of the dispersion liquid in the stirring tank, and granulation was performed with 10 circulations. A cooling jacket was attached around the Ebara Milder, and cooling water of about 15 ° C was circulated. The liquid mixture was supplied to granulate droplets of the core monomer composition.

1 part of sodium tetraborate decahydrate was added to the magnesium hydroxide colloidal dispersion in which the granulated core monomer composition was dispersed, and the mixture was placed in a reactor equipped with a stirring blade, and 85 After initiating the polymerization reaction at 0 ° C. and the polymerization conversion rate reaches almost 100%, a water-soluble initiator (manufactured by Wako Pure Chemical Industries, trade name “VA-0” is added to the aqueous dispersion of the polymerizable monomer for shell.
86 "= 2,2'-azobis (2-methyl-N- (2-
0.3 part of hydroxyethyl) -propionamide)) was dissolved and added to the reactor. After continuing the polymerization for 4 hours, the reaction was stopped to obtain an aqueous dispersion of core-shell type toner particles. While stirring the aqueous dispersion of toner particles obtained above, washing with sulfuric acid (25 ° C., 10 minutes),
The system pH was adjusted to 4.5 or lower. This aqueous dispersion was filtered, dehydrated and dried to give a volume average particle diameter (dv) of 7.2μ.
m, the particle size distribution (dv / dp) was 1.18, and the circularity by a flow type particle analyzer was 0.97. A scanning electron microscope image of the obtained toner is shown in FIG. As can be seen from FIG. 1, the obtained toner was spherical particles having concave portions on the surface of the particles. Hydrophobized colloidal silica (trade name "RX-10
0 "; manufactured by Nippon Aerosil Co., Ltd.) and mixed using a Henschel mixer to obtain a developer. The fluidity of this developer was 78. Table 1 shows the image evaluation results of the obtained developers.

[0040]

Example 2 The amount of magnesium oxide was adjusted to 10
A toner and a developer were obtained in the same manner as in Example 1 except that the number of parts was changed to one. The scanning electron microscope image of the obtained toner was spherical particles having concave portions on the surface of the particles, as in FIG. 1 of Example 1. Toner and developer characteristics,
Table 1 shows the image evaluation results of the developers.

(Example 3) The particle size of magnesium oxide was adjusted to 2
A toner and a developer were obtained in the same manner as in Example 1 except that the thickness was changed from 0.8 μm to 0.8 μm (trade name “Micromag 3-30” manufactured by Kyowa Chemical Co., Ltd.). The scanning electron microscope image of the obtained toner was spherical particles having concave portions on the surface of the particles, as in FIG. 1 of Example 1. Table 1 shows the characteristics of the toner and the developer and the image evaluation results of the developer.

(Comparative Example 1) Instead of magnesium oxide, magnesium hydroxide having an average particle size of 0.6 μm (Kyowa Chemical Co., Ltd., trade name “Magnesium hydroxide 200-06”)
H ”) was added, and a toner and a developer were obtained in the same manner as in Example 1. The scanning electron microscope image of the obtained toner is shown in FIG. 2, and the characteristics of the toner and the developer and the image evaluation result of the developer are shown in Table 1. As can be seen from FIG. 2, the obtained toner was spherical particles having no recess on the surface of the particles.

Comparative Example 2 80.5 parts of styrene and n
-Polymer methacrylic acid ester macromonomer composed of 19.5 parts of butyl acrylate, polymethacrylic acid ester macromonomer (trade name "AA6", manufactured by Toagosei Co., Ltd., Tg = 94)
C) 0.3 part, divinylbenzene 0.5 part, t-dodecyl mercaptan 1.2 part, carbon black (manufactured by Mitsubishi Chemical Corporation, trade name "# 25B") 7 parts, charge control resin (manufactured by Fujikura Kasei Co., One copy of the product name "FCA-1001-NS"
Wet crushing using a media type wet crusher,
10 parts of zinc carbonate powder (average particle size 1 μm) was added to obtain a polymerizable monomer composition. On the other hand, a dispersion was prepared by dispersing 2 parts of Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd.) in 300 parts of ion-exchanged water. On the other hand, 2 parts of methyl methacrylate and 65 parts of water were finely dispersed by an ultrasonic emulsifying machine to obtain an aqueous dispersion of a polymerizable monomer for shell. The particle size of the droplets of the polymerizable monomer for shell had a D90 of 1.7 μm.

The polymerizable monomer composition was added to the dispersion liquid obtained as described above, and droplets of the monomer composition were granulated in the same manner as in Example 1. The granulated monomer composition was placed in a reactor equipped with a stirring blade, the polymerization reaction was initiated at 85 ° C., and the polymerization conversion rate reached to about 100%. A water-soluble initiator (manufactured by Wako Pure Chemical Industries, Ltd., trade name “VA-086” = 2,2′-azobis (2
-Methyl-N- (2-hydroxyethyl) -propionamide)) 0.2 parts was dissolved and it was added to the reactor. After continuing the polymerization for 4 hours, the reaction was stopped to obtain an aqueous dispersion of core-shell type toner particles. The aqueous dispersion of toner particles obtained above is washed with an alkali, the aqueous dispersion is filtered and dehydrated to remove the dispersant, and the washing is again performed under acidic hydrochloric acid, and the aqueous dispersion is filtered and dehydrated. After doing
After drying, a toner was obtained. The scanning electron microscope image of the obtained toner was spherical particles having no recesses on the surface of the particles, as in FIG. 2 of Comparative Example 1. To 100 parts of toner,
Hydrophobized colloidal silica (trade name "RX-10
0 "; manufactured by Nippon Aerosil Co., Ltd.) and mixed using a Henschel mixer to obtain a developer. Table 1 shows the characteristics of the toner and the developer, and the image evaluation results of the developer.

Comparative Example 3 80.5 parts of styrene and n
-Polymer methacrylic acid ester macromonomer composed of 19.5 parts of butyl acrylate, polymethacrylic acid ester macromonomer (trade name "AA6", manufactured by Toagosei Co., Ltd., Tg = 94)
C) 0.3 part, divinylbenzene 0.5 part, t-dodecyl mercaptan 1.2 part, carbon black (manufactured by Mitsubishi Chemical Corporation, trade name "# 25B") 7 parts, charge control resin (manufactured by Fujikura Kasei Co., One copy of the product name "FCA-1001-NS"
Wet crushing using a media type wet crusher,
10 parts of tricalcium phosphate (average particle size: 1.5 μm) and 0.1 part of an aluminum coupling agent (manufactured by Ajinomoto Fine-Techno Co., Inc., trade name “Planeact AL-M”) were added and stirred for 30 minutes. A polymerizable monomer composition was obtained.
On the other hand, 5 parts of tricalcium phosphate in 300 parts of ion-exchanged water
Parts and 0.1 part of sodium dodecylbenzene sulfonate were added to prepare a dispersion liquid. On the other hand, 2 parts of methyl methacrylate and 65 parts of water were finely dispersed by an ultrasonic emulsifying machine to obtain an aqueous dispersion of a polymerizable monomer for shell. D90 of the droplets of the polymerizable monomer for shell was 1.6 μm.

The polymerizable monomer composition was added to the dispersion liquid obtained above, and the droplets of the monomer composition were granulated in the same manner as in Example 1. The granulated monomer composition was placed in a reactor equipped with a stirring blade, the polymerization reaction was initiated at 85 ° C., and the polymerization conversion rate reached to about 100%. Water-soluble initiator (manufactured by Wako Pure Chemical Industries, Ltd., trade name "VA-086" = 2,2'-azobis (2
-Methyl-N- (2-hydroxyethyl) -propionamide)) 0.2 parts was dissolved and it was added to the reactor. After continuing the polymerization for 4 hours, the reaction was stopped to obtain an aqueous dispersion of core-shell type toner particles. The aqueous dispersion of toner particles obtained as described above was washed under acidic conditions with hydrochloric acid, the aqueous dispersion was filtered and dehydrated, and then dried to obtain a toner. The scanning electron microscope image of the obtained toner was spherical particles having no recesses on the surface of the particles, as in FIG. 2 of Comparative Example 1. To 100 parts of the obtained toner, 1 part of hydrophobized colloidal silica (trade name "RX-100"; manufactured by Nippon Aerosil Co., Ltd.) was added and mixed using a Henschel mixer to obtain a developer. Table 1 shows the characteristics of the toner and the developer, and the image evaluation of the developer.

The following can be seen from Table 1. The developer of Comparative Example 1, which uses a toner produced by using a metal hydroxide other than the metal oxide specified in the present invention as the metal fine particles, is inferior in the toner cleaning property, and the durable image after continuous printing is I found it bad. Comparative Example 2 using a toner produced by using metal carbonate other than the metal oxide defined in the present invention as the metal fine particles and silica other than the poorly water-soluble metal hydroxide defined in the present invention as the dispersion stabilizer. It was found that the developer was inferior in the cleaning property of the toner, the initial image was a little bad, and the durable image after continuous printing was bad. Comparison using a toner produced using a metal phosphate other than the metal oxide defined in the present invention as the metal fine particles and a tricalcium phosphate other than the poorly water-soluble metal hydroxide defined in the present invention as the dispersion stabilizer. It was found that the developer of Example 3 was slightly inferior in the toner cleaning property, the initial image was slightly bad, and the durable image after continuous printing was also bad.

On the other hand, it can be seen that the developers of Examples 1 to 3 using the toner obtained by the manufacturing method of the present invention have excellent toner cleaning properties and good initial images and durable images.

[0050]

According to the present invention, the particle size distribution is narrow, the particle shape can be maintained basically spherical, and the concave portion can be surely formed on the particle surface, and the cleaning property by the cleaning blade is excellent, It is possible to provide a toner that is excellent in an initial image and a durable image after continuous printing, and a method for producing the toner.

[Brief description of drawings]

FIG. 1 is a view showing a scanning electron microscope image of the toner manufactured in Example 1.

FIG. 2 is a view showing a scanning electron microscope image of the toner manufactured in Comparative Example 1.

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Claims (3)

[Claims] 1. A polymerizable monomer composition containing at least a polymerizable monomer, a colorant and metal oxide particles is dispersed in an aqueous medium containing a sparingly water-soluble metal hydroxide, followed by polymerization. A method for producing a toner, in which toner particles are obtained by doing so, and the metal oxide particles exposed on the surface of the toner particles are removed by a chemical method. 2. The method for producing a toner according to claim 1, wherein the poorly water-soluble metal hydroxide and the metal oxide particles are composed of the same metal element. 3. The volume average particle diameter (Dv) is 1 to 10 μm,
The particle size distribution (Dv / Dp), which is the ratio of the volume average particle size to the number average particle size (Dp), is 1.2 or less, and the average circularity is 0.9.
0 to 0.99, toner comprising toner particles having concave portions on the particle surface and an external additive