JP2001281915A - Toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner with which an excellent image can be obtained even on recycled paper. SOLUTION: The toner contains amorphous silica spheric fine particles having <=1.0 ppm metal impurity content except for silicon and 10 to 300 m2/g specific surface area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic latent image formed by an electrophotographic method, an electrostatic recording method, or the like.

[0002]

2. Description of the Related Art Conventionally, an electrostatic latent image formed in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus is first developed with toner, and then the formed toner image is used as required. After being transferred onto a transfer material such as paper, it is fixed by various methods such as heating, pressing, and solvent vapor.
As a toner, generally, a colorant, a charge control agent, a release agent, and the like are melt-mixed and uniformly dispersed in a thermoplastic resin serving as a binder resin component to form a composition, and then the composition is pulverized. ,
A colorant, a charge control agent, a release agent and the like are dissolved or dispersed in a pulverized toner by a pulverization method of obtaining colored particles by classifying, or a polymerizable monomer which is a binder resin raw material,
Polymerized toners are generally used, in which a polymerization initiator is added, heated to a polymerization temperature, and after polymerization, filtered, washed, dehydrated, and dried to obtain colored particles. By such a method, it is possible to produce a toner having excellent properties to some extent, but it relates to improvement of image quality such as higher image quality and stable image quality even under poor environment such as high temperature and high humidity and low temperature and low humidity. The demand is only growing.

[0003] In response to such demands, proposals have been made to address such demands by designing a binder resin and incorporating functional components such as a charge control agent and a release agent. There is also a proposal to improve the image quality of the toner by adding an external additive typified by fine particles. In using such inorganic fine particles as an external additive, studies have been made to improve the image quality and the storage stability by hydrophobic treatment or controlling the particle size (JP-A-61-27796).
No. 4, JP-A-2-167559, etc.).

[0004] In recent years, from the viewpoint of environmental protection, recycled paper has been widely used mainly in offices. In offices, there are many opportunities for continuous printing, and high-speed printing machines tend to be used. Therefore, recently, even when printing continuously on recycled paper using a high-speed printing machine, good image quality is required.

[0005]

SUMMARY OF THE INVENTION The present inventor has found that when a conventional toner is applied to recycled paper, only an image having a lot of fog and blurring and a low print density can be obtained. Therefore, as a result of intensive studies to obtain a good image even on recycled paper, it was found that when certain kinds of silica fine particles having a specific range of specific surface area with a small content of metal impurities were used as external additives for spherical colored particles, this problem was solved. Have been found, and the present invention has been completed.

[0006]

According to the present invention, there is provided amorphous silica spherical fine particles having a metal impurity content other than silicon of 1.0 ppm or less and a specific surface area of 5 to 100 m ² / g. A toner is provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The toner of the present invention is composed of colored particles and specific spherical silica fine particles.

[0008] The colored particles used in the present invention are, for example, melt-kneaded with a binder resin, a coloring agent, and other additives as required, and then cooled and pulverized and classified so as to have a desired particle size distribution. Even when produced by a pulverization method, for example, a polymerizable monomer containing a polymerizable monomer and a colorant, which are raw materials of a binder resin, and other additives as necessary is polymerized in an appropriate aqueous medium. It may be manufactured by the following polymerization method. From the viewpoint of obtaining a toner that gives good image quality even with recycled paper, it is preferable to use one manufactured by a polymerization method. Production by a polymerization method is usually performed by a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, or the like.

[0009] The colored particles may have a capsule structure obtained by combining different polymers, such as a capsule structure and a core-shell structure. The colored particles having a capsule structure (hereinafter, sometimes referred to as capsule toner) may be obtained by a pulverization method or may be obtained by a polymerization method.

[0010] The particle size of the colored particles is determined by the volume average particle size (dv).
Is 3 to 12 μm, preferably 4 to 10 μm, and the ratio (dv / dn) of the volume average particle diameter to the number average particle diameter (dn) is desirably in the range of 1 to 1.3.

(Binder Resin) Specific examples of the binder resin include:
Conventionally widely used resins for toner, for example,
Polymers of styrene such as polystyrene, poly p-chlorostyrene, polyvinyltoluene and their substituted polymers; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene Copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-
Octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-
Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile- Indene copolymer,
Styrene copolymers such as styrene-maleic acid copolymer and styrene-maleic acid ester copolymer; polymethyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral , Polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, etc., and these can be used alone or in combination. .

(Polymerizable monomer) As a preferable polymerizable monomer used for producing colored particles by a polymerization method, a monovinyl monomer can be exemplified. Specifically, styrene monomers such as styrene, vinyltoluene and α-methylstyrene; acrylic acid, methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylic Cyclohexyl acrylate, isobonyl acrylate, cyclohexyl methacrylate, isobonyl methacrylate, dimethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dimethylaminoethyl methacrylate, acrylamide Derivatives of acrylic acid or methacrylic acid such as methacrylamide; monoolefinic monomers such as ethylene, propylene and butylene; vinyl esters such as vinyl acetate and vinyl propionate Vinyl methyl ether, vinyl ethers such as vinyl ethyl ether, vinyl methyl ketone, vinyl ketones such as methyl isopropenyl ketone; 2-vinylpyridine,
Monovinyl monomers such as nitrogen-containing vinyl compounds such as 4-vinylpyridine and N-vinylpyrrolidone; The monovinyl-based monomer may be used alone, or a plurality of monomers may be used in combination. Of these monovinyl monomers, a styrene monomer or a combination of a styrene monomer and a derivative of acrylic acid or methacrylic acid is preferably used.

(Crosslinkable Compound) In the production of colored particles by the polymerization method, the use of a crosslinkable compound such as a crosslinkable monomer or a crosslinkable polymer together with the polymerizable 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 derivatives thereof;
Diethylenically unsaturated carboxylic esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; (meth) derived from alcohols having both aliphatic terminals such as 1,4-butanediol and 1,9-nonanediol
Acrylate; divinyl compounds such as N, N-divinylaniline and divinyl ether; and compounds having three or more vinyl groups. The crosslinkable polymer is
Examples include polyethylene, polypropylene, polyester, and polysiloxane-derived (meth) acrylates having two or more hydroxyl groups in the molecule. These crosslinkable monomers and crosslinkable polymers can 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 polymerizable monomer. Such a polymerizable monomer or a crosslinkable compound is polymerized to form a binder resin.

(Polymerization Initiator) Examples of the polymerization initiator used for producing colored particles by the polymerization method include persulfates such as potassium persulfate and ammonium persulfate; 4,4'-azobis (4-
Cyanovaleric acid), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis-2-methyl-
N-1,1′-bis (hydroxymethyl) -2-hydroxyethylpropioamide, 2,2′-azobis (2,
Azo compounds such as 4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, and 1,1′-azobis (1-cyclohexanecarbonitrile); methyl ethyl peroxide, di-t-butyl peroxide, Acetyl peroxide, dicumyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-butyl perbutyl neodecanoate, t-hexyl peroxy-2-ethyl hexa Noate, t-butylperoxypivalate, t-hexylperoxypivalate, di-isopropylperoxydicarbonate, di-t-butylperoxyisophthalate, 1,1 ', 3,3'-tetramethylbutyl Peroxy-2-ethylhexanoate, t-
Peroxides such as butyl peroxyisobutyrate can be exemplified. Further, a redox initiator obtained by combining these polymerization initiators and a reducing agent can be exemplified.

Among these, it is particularly preferable to select an oil-soluble polymerization initiator soluble in the polymerizable monomer to be used, and if necessary, a water-soluble polymerization initiator can be used in combination therewith. . The polymerization initiator comprises a polymerizable monomer 10
0.1 to 20 parts by weight, preferably 0.3 to 15 parts by weight, more preferably 0.5 to 10 parts by weight, based on 0 parts by weight. The polymerization initiator can be added in advance to the polymerizable monomer composition, but in some cases, can be added to the suspension after the completion of the granulation step.

(Colorant) As the colorant contained in the colored particles, various pigments and / or dyes can be used in addition to carbon black and titanium white. It is preferable to use black carbon black having a primary particle size of 20 to 40 nm. If the primary particle size is small, dispersion of carbon black cannot be obtained, resulting in a toner with much fog. On the other hand, when carbon black having a large primary particle size is used, the amount of the polyvalent aromatic hydrocarbon compound increases, and environmental safety may decrease.

When a full-color toner is obtained, a yellow colorant, a magenta colorant and a cyan colorant are usually used. Compounds such as azo pigments and condensed polycyclic pigments are used as the yellow colorant. Specifically, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17,
62, 65, 73, 83, 90, 93, 97, 120,
138, 155, 180 and 181.

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, 90, 1
12, 114, 122, 123, 144, 146, 14
9, 163, 170, 184, 185, 187, 20
2, 206, 207, 209, 251, C.I. I. Pigment Violet 19 and the like.

As the cyan coloring agent, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds and the like can be used. Specifically, C.I. I. Pigment Blue 2,
3, 6, 15, 15: 1, 15: 2, 15: 3, 15:
4, 16, 17, and 60, and the like. The amount of such a coloring agent used is 100 parts by weight of the binder resin or the polymerizable monomer.
It is 1 to 10 parts by weight with respect to parts by weight.

(Other Additives) In order to improve the performance of the toner, a release agent, a charge control agent and the like can be added. During the production by the polymerization method, a molecular weight modifier and the like can be further added.

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, low molecular weight polypropylene having oxidized molecular terminals, and low molecular weight terminal modified polypropylene having a molecular terminal substituted by an epoxy group. And terminal-modified polyolefin waxes, such as block polymers of low-molecular-weight polyethylene, low-molecular-weight oxidized polyethylene with low molecular weight, epoxy-terminated low-molecular-weight polyethylene and block polymers of these and low-molecular-weight polypropylene; candelilla, carnauba, rice Wax, wood wax, jojoba, etc .; plant natural wax; petroleum wax such as paraffin, microcrystalline, petrolactam and its modified wax; montan, ceresin, ozokerai Synthetic waxes such as Fischer-Tropsch wax; polyfunctional ester compounds such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, dipentaerythritol hexamyristate; distearyl phthalate, dibehenyl phthalate, and isophthalic acid Aromatic polycarboxylic acid alkyl ester compounds such as distearyl, dibehenyl isophthalate, and distearyl monobehenyl trimellitate (the alkyl moiety has 15 or more carbon atoms);
One type or two or more types are exemplified. These are used alone or in combination of two or more.

Of these, synthetic waxes, end-modified polyolefin waxes, petroleum waxes, and polyfunctional ester compounds are preferred. Among the polyfunctional ester compounds, pentaerythritol esters having an endothermic peak temperature in the range of 30 to 200 ° C., preferably 50 to 180 ° C., preferably 60 to 160 ° C. in a DSC curve measured by a differential scanning calorimeter. And the endothermic peak temperature is 5
A polyester compound such as dipentaerythritol ester in the range of 0 to 80 ° C. is used for fixing as a toner.
It is particularly preferable in terms of the releasability balance. In particular, the molecular weight is 1000 or more, and 25 parts per 100 parts by weight of styrene.
The dipentaerythritol ester having an acid value of not more than 10 mg / KOH or an aromatic polycarboxylic acid alkyl ester compound (having an alkyl portion having 15 or more carbon atoms) dissolved at 5 ° C. or more and having an acid value of 10 mg / KOH or less was significantly reduced in fixing temperature. Shows the effect. Endothermic peak temperature is a value measured by ASTM D3418-82. The release agent is 0.1 to 20 parts by weight based on 100 parts by weight of the binder resin or the polymerizable monomer,
Preferably, 1 to 15 parts by weight is used.

The charge control agent is preferably contained in the colored particles in order to improve the chargeability of the toner. Various charge control agents can be used as the charge control agent. As the charge control agent, for example, Bontron N01
(Orient Chemical Co., Ltd.), Nigrosine Base EX (Orient Chemical Co., Ltd.), Spiro Black TRH (Hodogaya Chemical Co., Ltd.), T-77 (Hodogaya Chemical Co., Ltd.), Bontron S-34 (Orient Chemical Co., Ltd.), Bontron E -81
(Orient Chemical Co.), Bontron E-84 (Orient Chemical Co.), Bontron E-89 (Orient Chemical Co.), Bontron F-21 (Orient Chemical Co.),
COPY CHRGE NX (manufactured by Clariant), C
OPY CHRGE NEG (Clariant),
TNS-4-1 (manufactured by Hodogaya Chemical Co., Ltd.), TNS-4-2
Charge control agents such as (Hodogaya Chemical Co., Ltd.) and LR-147 (Nippon Carlit Co., Ltd.), JP-A-11-15192, JP-A-3-175456, JP-A-3-243.
No. 954, etc., quaternary ammonium (salt) group-containing copolymers, JP-A-3-243954, JP-A-1
A charge control agent (charge control resin) such as a sulfonic acid (salt) group-containing copolymer described in JP-A-217264 and JP-A-3-15858 can be used. The charge control resin is preferable because it has high compatibility with the binder resin, is colorless, and can obtain a toner having stable chargeability even in continuous color printing at high speed. The charge control agent is usually used with respect to 100 parts by weight of the binder resin or the polymerizable monomer.
It is used in a proportion of 0.01 to 10 parts by weight, preferably 0.1 to 7 parts by weight.

(Magnetic Material) The colored particles may contain a magnetic material. In this case, as a material to be used, magnetite, γ-iron oxide, ferrite, iron oxide such as iron-rich ferrite; metals such as iron, cobalt, nickel, or these metals and aluminum, cobalt, copper,
Examples include alloys with metals such as lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

(Dispersion Stabilizer) For example, when producing colored particles by a suspension polymerization method, it is preferable to use a dispersion stabilizer. Specific examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide; Such as metal compounds, aluminum hydroxide,
Metal hydroxides such as magnesium hydroxide and ferric hydroxide;
Water-soluble polymers such as polyvinyl alcohol, methyl cellulose, and gelatin; anionic surfactants, nonionic surfactants, and amphoteric surfactants. Among these, dispersion stabilizers containing metal compounds, especially colloids of poorly water-soluble metal hydroxides, are preferred because they can narrow the particle size distribution of polymer particles and improve the sharpness of images. is there.

The dispersion stabilizer containing a colloid of a poorly water-soluble metal hydroxide is not limited by its production method, but is difficult to obtain by adjusting the pH of an aqueous solution of a water-soluble polyvalent metal salt compound to 7 or more. It is preferable to use a colloid of a water-soluble metal hydroxide, particularly a colloid of a poorly water-soluble metal hydroxide formed by a reaction of a water-soluble polyvalent metal salt compound with an alkali metal hydroxide in an aqueous phase.

The colloid of the poorly water-soluble metal compound has a number particle size distribution D50 (50% cumulative value of the number particle size distribution) of 0.5.
It is preferable that D90 (90% cumulative value of the number particle size distribution) be 1 μm or less. When the particle size of the colloid is large, the stability of polymerization is lost, and the storage stability of the toner is reduced.

The dispersion stabilizer is usually used in a proportion of 0.1 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer.
If the ratio is too low, it is difficult to stably disperse the droplets of the polymerizable monomer composition, and an aggregate of polymer particles is likely to be generated. Conversely, if this ratio is too high, the viscosity in the aqueous dispersion medium increases, and the distribution of the polymerized toner particle size is widened, so that the yield decreases.

When the capsule toner is used as the colored particles, a method such as a spray drying method, an interfacial reaction method, an in situ polymerization method, and a phase separation method can be employed. In particular, the in situ polymerization method and the phase separation method are preferable because of high production efficiency.

The production method of the capsule toner is in situ.
This will be described below by taking a polymerization method as an example. In an aqueous dispersion medium containing a dispersion stabilizer, a polymerizable monomer composition containing at least a polymerizable monomer (polymerizable monomer for a core), a colorant, and a release agent (a single monomer for a core) Body composition),
Capsule toner is produced by polymerizing using a polymerization initiator to produce core particles, further adding a polymerizable monomer (monomer for shell) for forming a shell and a polymerization initiator, and polymerizing. Can be obtained. The core particles can be obtained in the same manner as the toner obtained by the above-mentioned suspension polymerization method.

(Monomer for core) As the monomer for core, the same as the above-mentioned polymerizable monomer can be exemplified. Among them, those capable of forming a polymer having a glass transition temperature of usually 60 ° C or lower, preferably 40 to 60 ° C are desirable as the monomer for the core. If the glass transition temperature is too high, the fixing temperature increases, and if the glass transition temperature is too low, the storage stability decreases. Usually, the core monomer is often used alone or in combination of two or more.

Here, the glass transition temperature (Tg) of the polymer
Is a calculated value (referred to as calculated Tg) calculated by the following formula according to the type of the monomer used and the usage ratio. 100 / Tg = W1 / T1 + W2 / T2 + W3 / T3 +
..., where Tg: glass transition temperature (absolute temperature) of the copolymer W1, W2, W3 ...: wt% of monomers constituting the copolymer T1, T2, T3 ...: constituting the copolymer The glass transition temperature (absolute temperature) of a homopolymer composed of the respective monomers described below indicates that the numbers assigned to W and T are numerical values for the same monomer.

In the case of a capsule toner, the core particles have a volume average particle size of usually 2 to 10 μm, preferably 2 to 9 μm,
More preferably, it is 3 to 8 μm. The volume average particle diameter (dv) / number average particle diameter (dp) is usually 1.7 or less,
Preferably it is 1.5 or less, more preferably 1.3 or less. A toner having such a particle size and a particle size distribution can be obtained by the above-described suspension polymerization.

A shell monomer is added to the obtained core particles, and the resulting mixture is polymerized again to form a shell layer of the encapsulated toner. As a specific method of shell formation, a method of continuously polymerizing by adding a monomer for shell to a reaction system of a polymerization reaction performed to obtain the core particles, or a core obtained by another reaction system A method in which particles are charged, a monomer for a shell is added thereto, and polymerization is performed in a stepwise manner can be exemplified. The monomer for the shell component can be added all at once to the reaction system, or can be added continuously or intermittently using a plunger pump or the like.

(Monomer for Shell) The monomer for shell desirably gives a polymer having a glass transition temperature higher than the glass transition temperature of the polymer constituting the core particles. As monomers constituting the shell monomer, monomers that form a polymer having a glass transition temperature of more than 80 ° C., such as styrene and methyl methacrylate, may be used alone or in combination of two or more. it can. Here, the glass transition temperature is a value calculated in the same manner as in the above method.

It is necessary to set the glass transition temperature of the polymer composed of the monomer for shell at least higher than the glass transition temperature of the polymer composed of the monomer for core particles. The glass transition temperature of the polymer obtained from the shell monomer is generally higher than 50 ° C. and 120 ° C. or lower, preferably higher than 60 ° C. and 110 ° C. or lower, more preferably 80 ° C. in order to improve the storage stability of the polymerized toner. Exceed 105 ° C or less. The difference in glass transition temperature between the polymer composed of the monomer for core particles and the polymer composed of the monomer for shell,
It is usually at least 10 ° C, preferably at least 20 ° C, more preferably at least 30 ° C.

(Radical Initiator for Shell) When a monomer for shell is added, it is preferable to add a water-soluble radical initiator in order to easily obtain a capsule toner.
When the water-soluble radical initiator is added during the addition of the shell monomer, the water-soluble radical initiator enters near the outer surface of the core particle to which the shell monomer has migrated, and the polymer ( It is considered that this is because a shell is easily formed.

Examples of the water-soluble radical initiator include persulfates such as potassium persulfate and ammonium persulfate;
Azobis (4-cyanovaleric acid), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis-2-methyl-N-1,1′-bis (hydroxymethyl) -2 Azo initiators such as hydroxyethylpropioamide; combinations of oil-soluble initiators such as cumene peroxide with a redox catalyst; The amount of the water-soluble radical initiator is usually 0.0
0.01 to 1% by weight.

The core monomer and the shell monomer are usually used in a weight ratio of 80/20 to 99.9 / 0.1. If the proportion of the shell monomer is too small, the effect of improving the storage stability is small, and if it is too large, the effect of improving the reduction of the fixing temperature is small.

In the case of a capsule toner, the average thickness of the shell is usually 0.001 to 1.0 μm, preferably 0.001 to 1.0 μm.
3 to 0.5 μm, more preferably 0.005 to 0.2 μm
m. As the thickness increases, the fixability decreases, and as the thickness decreases, the storability decreases. In the present invention, it is not necessary that the entire core of the capsule toner is covered with the shell. The core particle diameter and shell thickness of the capsule toner can be obtained by directly measuring the particle size and shell thickness randomly selected from the electron micrograph. When it is difficult to observe the core and the shell with an electron microscope, the particle size of the core particles is directly measured immediately before the shell forming step, and the thickness of the shell is determined by the monomer used to form the shell used in the toner production. It can be calculated from the quantity.

The colored particles according to the present invention have a sphericity of from 1 to 1.
It is spherical in the range of 1.3. Also, the colored particles are
BET specific surface area (A) [m ² / g], number average particle size (d
n) Product of [μm] and true specific gravity (D) (A × dn × D)
Is preferably in the range of 5 to 10.

(External Additive) An external additive is added to the above-described colored particles.
Amorphous silica spherical fine particles (hereinafter referred to as spherical silica)
To obtain the toner of the present invention. Spherical silica
Can be used as an external additive, so that
A quality-imparting toner can be obtained.
^{The amount of the external additive is not particularly limited.
Usually 0.1 part by volume.
05 to 10 parts by weight, preferably 0.1 to 6 parts.}

The spherical silica according to the present invention has a metal impurity content other than silicon of 1.0 ppm or less, preferably 0.1 ppm or less.
It is 5 ppm or less. If the content of metallic impurities in the spherical silica is large, the charge amount under high temperature and high humidity is greatly reduced, which may cause a problem that fogging is likely to occur. The spherical silica according to the present invention has a specific surface area of 5 to 100 m ² / g, preferably 10 to 80 m ² / g, more preferably 10 to 50 m ² / g.
The particle size distribution is 10-500 nm in m ² / g. When the specific surface area is too small, there is a tendency that a problem occurs when printing on recycled paper at low temperature and low humidity. When the specific surface area is too high, there is a tendency that filming occurs.

The spherical silica according to the present invention is obtained, for example, by heating and evaporating high-purity alkoxysilane, introducing it into an inert gas (nitrogen gas, argon gas, etc.) stream, introducing it into an oxyhydrogen flame burner, It is obtained by burning and decomposing in a flame in which a combustible gas such as oxygen gas, nitrogen gas and methane gas is present. Kind of alkoxysilane,
Further, the specific surface area can be controlled by changing the types of various gases used in this step and their usage ratios.

The alkoxysilane has the general formula R ¹ _X Si
(OR ² ) A compound represented by _4-X . In this equation,
R ¹ and R ² are a linear or branched alkyl having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group and a tert-butyl group. Group, 2-propenyl group, 2-butenyl group, 1-methyl-2-propenyl group, 2-methyl-2
A straight-chain or branched alkenyl group having 3 to 4 carbon atoms such as a propenyl group, and x is an integer of 0 to 4;

Examples of such an alkoxysilane include methyltrimethoxysilane, tetramethoxysilane, ethyltrimethoxysilane, n-propyltriethoxysilane, methyltributoxysilane, diethyldipropoxysilane, and trimethylbutoxysilane. The spherical silica of the present invention can also be produced using such an alkoxysilane oligomer or polymer. The method for increasing the purity of the alkoxysilane is not particularly limited, but a general method such as distillation may be employed.

The spherical silica may be subjected to a hydrophobic treatment with a silane coupling agent or silicone oil. The spherical silica subjected to the hydrophobic treatment preferably has a hydrophobicity of 30 to 90% as measured by a methanol method.

In the present invention, in addition to spherical silica, organic or inorganic fine particles generally used as an external additive of a toner can be used in combination. Organic fine particles include methacrylate polymer particles, acrylate polymer particles, styrene-methacrylate copolymer particles, styrene-acrylate copolymer particles, zinc stearate, calcium stearate, and a core of methacrylic acid. Core-shell type particles in which a shell is formed of a styrene polymer in an ester copolymer are exemplified. Silicon oxide, aluminum oxide, zinc oxide, tin oxide, barium titanate, strontium titanate, etc. other than spherical silica can also be used as the inorganic fine particles. Fine particles other than the spherical silica account for 50% by weight based on the total amount of the external additive.
Below, it is desirable to use together in the range of preferably 45% by weight or less.

[0049]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to these examples. In addition, parts and%
Are by weight unless otherwise specified.

(Evaluation Method) <Physical Properties of Colored Particles> Volume Average Particle Size The volume average particle size (dv) and the particle size distribution of the colored particles (toner particles), that is, the volume average particle size and the number average particle size (dp) The ratio (dv / dp) was measured with a Multisizer (manufactured by Beckman Coulter). The measurement by the 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. -Number average particle diameter The particle diameter of the external additive is determined by taking an electron micrograph of each particle and using the photograph as an image processing / analyzing device Luzex IID [Co., Ltd.]
This is an average value measured and analyzed under the conditions that the area ratio of particles to the frame area is 2% at the maximum and the total number of particles processed is 100.

<Spherical silica physical properties>-About 500 mg of silica was weighed and dissolved in a 100 ml plastic container with a mixed acid. After dissolution, the resultant was diluted with pure water, and a plasma emission analyzer (manufactured by Seiko Denshi Kogyo Co., Ltd .: Model SPS1200
AR), Na, K, Mg, Ca, Al, Cr, F
It is the total value (ppm) of the measured values (ppm) of the amounts of e, Cu, Mn and U. Specific surface area The specific surface area (A) is a value (m) measured by a BET method using an automatic specific surface area measuring apparatus Model 2200 manufactured by Shimadzu Corporation.
² / g). Degree of hydrophobicity 0.2 g of spherical silica powder was weighed into a 200 ml beaker, 50 ml of pure water was added, and methanol was gradually added under the liquid level while stirring with a magnetic stirrer. The point where powder is no longer recognized on the liquid surface is the end point,
This is a value calculated by the following equation. Degree of hydrophobicity (%) = X / (50 + X) × 100 X; Methanol usage (ml)

<Evaluation of image quality> Fog Commercially available non-magnetic one-component developing system printer (printing speed:
(12 sheets / minute), put the developer to be evaluated in the developing device of this printer, and apply 35 ° C. × 80 RH%
After standing overnight in an (H / H) environment, 7,500 sheets of continuous printing were performed from the beginning, and the fog of the non-image area of the photoreceptor was examined with a whiteness meter (manufactured by Nippon Denshoku). An adhesive tape (Scotch Mending Tape 81 manufactured by Sumitomo 3M Limited) to which printing is stopped during printing and toner of a non-image area on the photoreceptor after development is adhered thereto
0-3-18) is attached to printing paper, and its whiteness B,
Affix only the adhesive tape to the printing paper, and
Then, the fog value calculated by the formula of fog (%) = (AB) was used. The measurement was performed on the 10th sheet and the 7500th sheet. -7,500 sheets printing state The printing state of the 7,500 sheets printed by the measurement of fog was visually checked.

Surface potential A recycled paper is set in a commercially available printer (printing speed: 12 sheets / min), toner is added, and the image is left for a day and night at 23 ° C. and 50% relative humidity. This is a value obtained by printing, stopping in the middle of printing, and thereafter applying a surface voltmeter to the undeveloped toner portion on the developing roller at a fixed distance to measure the amount of surface potential. The measurement was performed on the 10th sheet and the 7500th sheet.

(Examples 1-2, Comparative Examples 1-2) 80 parts of styrene, 20 parts of n-butyl acrylate, carbon black (trade name "# 25B", manufactured by Mitsubishi Chemical Corporation; primary particle size: 4)
0 parts), 0.5 parts of a charge control agent (trade name “Spiron Black TRH”, manufactured by Hodogaya Chemical Co., Ltd.), 0.6 parts of divinylbenzene, 1 part of t-dodecyl mercaptan, and sasol wax (trade name “ Paraflint spray
30 "(manufactured by Sasol Co.) was dispersed in a bead mill at room temperature to obtain a uniform mixed solution. While stirring the mixture, 5 parts of a polymerization initiator “Perbutyl O” (trade name, manufactured by NOF Corporation) was added, and stirring was continued until the droplets became uniform to form a polymerizable monomer composition. Obtained.

On the other hand, in an aqueous solution obtained by dissolving 9.5 parts of magnesium chloride (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water, 4.8 parts of sodium hydroxide (alkali metal hydroxide) was added to 50 parts of ion-exchanged water. The aqueous solution in which was dissolved was gradually added under stirring to prepare a magnesium hydroxide colloid (poorly water-soluble metal hydroxide colloid) dispersion. The polymerizable monomer composition was charged into the colloid, and the mixture was subjected to high shear stirring at a rotation speed of 12000 rpm using a TK homomixer to granulate droplets of the polymerizable monomer mixture. The aqueous dispersion of the granulated polymerizable monomer mixture is put into a reactor equipped with a stirring blade, a polymerization reaction is started at 90 ° C., polymerization is performed for 8 hours, and then cooling is performed. I got

While stirring the aqueous dispersion of the polymer particles obtained as described above, the pH of the system was adjusted to 4 or less with sulfuric acid, acid washing was performed, water was separated by filtration, and 500 parts of ion-exchanged water was newly added. In addition, the slurry was reslurried and washed with water. After that, dehydration and washing with water were repeated several times again, and the solid content was separated by filtration, followed by drying at 45 ° C. for 2 days and night with a drier to obtain colored particles. The volume average particle size of the colored particles is 7.
8 μm, and a volume average particle diameter (d
v) / number average particle diameter (dp) was 1.25.

The colored particles 10 obtained by the method described above
0 parts, any one of spherical silicas A to E, and inorganic fine particles (silica particles, manufactured by Nippon Aerosil Co., Ltd .;
A number average particle size: 12 nm) and organic fine particles (having a capsule structure of styrene shell with polymethyl methacrylate particles as a core: number average particle size 0.4 μm, sphericity: 1.16) were mixed, and Henschel was mixed. 10 with a mixer
For 1 minute at a rotation speed of 1400 rpm to obtain a toner.
The quality of the obtained toner was evaluated. Table 1 shows the results
Shown in

[0058]

[Table 1]

The following spherical silicas A to E were used. Spherical silica A: metal impurity content 0.29 ppm, specific surface area 9.1 m ² / g: hydrophobically treated with hexamethyldisilazane Spherical silica B: metal impurity content 0.37 ppm, specific surface area 27 m ² / g: silicone Oil (Shin-Etsu Chemical Co., Ltd.
What was hydrophobized with "FK96-100" (trade name)) Spherical silica C: metal impurity content 5 ppm, specific surface area 39
m ² / g: hydrophobically treated with hexamethyldisilazane Spherical silica D: metal impurity content 0.26 ppm, specific surface area 4.5 m ² / g: silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.
"FK96-100" (trade name)) subjected to hydrophobic treatment Spherical silica E: metal impurity content 5 ppm, specific surface area 13
0 m ² / g: hydrophobically treated with hexamethyldisilazane

From the above results, in the example using the specific external additive, there was no fog on the photoreceptor, the good printing specified in the present invention was obtained, and the external additive out of the range of the present invention was obtained. It was found that, in the comparative example using No., after printing 7,500 sheets, there was fogging on the photoreceptor, and the print was blurred or stained. Even if the print looks good, fog on the photoreceptor adversely affects the print in a poor environment such as high temperature and high humidity, and thus such a toner cannot be said to be a good quality toner.

[0061]

According to the present invention, it is possible to obtain an image having high print density without fogging or blurring even on recycled paper.

Claims (1)

[Claims] 1. The content of metal impurities other than silicon is 1.0 p
pm or less and a specific surface area of 5 to 100 m ² / g.