JP2002139862A - Electrostatic image developing toner - Google Patents

Abstract

(57) [Problem] To provide a toner capable of obtaining an image having a high print density without fog even when the number of prints is increased in various environments, particularly under high temperature and high humidity. An external additive containing silica fine particles (A) hydrophobically treated with a siloxane compound, wherein the number average primary particle size of the particles is 5 to 30 nm and the amount of the siloxane compound extracted with tetrahydrofuran is 1% by weight or less. The agent is added to the colored particles to obtain an electrostatic image developing toner.

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. In particular, the present invention relates to a toner free from fogging, blurring and filming even when transferred to a transfer material such as paper or OHP.

[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 pulverized toner that obtains colored particles by classification, a colorant, a charge control agent, and a release agent are dissolved or dispersed in a polymerizable monomer that is a binder resin raw material, and after adding a polymerization initiator,
Suspension polymerized toner obtained by suspending in an aqueous dispersion medium containing a dispersion stabilizer, heating to a predetermined temperature to initiate polymerization, and filtering, washing, dehydrating and drying after polymerization to obtain colored particles, emulsification Particles of a binder resin containing a polar group obtained by polymerization, and particles containing a colorant and a charge control agent are stirred at a temperature higher than the glass transition temperature of the binder resin to associate the particles. Emulsion polymerization toners that obtain colored particles by filtration, drying and drying are used.

In recent years, there has been a growing demand for higher image quality, such as higher image quality, and stable image quality even in poor environments such as high temperature, high humidity, and low temperature, low humidity. ing. In response to such demands, it has been proposed to design binder resins and to include functional components such as charge control agents and release agents.
There is also a proposal to improve the image quality of the toner by adding an external additive such as organic or inorganic fine particles to the obtained colored particles.
Among the above-mentioned inorganic fine particles, silica fine particles, particularly silica fine particles whose particle surfaces have been subjected to a hydrophobic treatment, are widely used from the viewpoint of cost and effects on toner physical properties.

For example, Japanese Patent Application Laid-Open No. 46-5782 discloses
Has an organic group having 1 to 3 carbon atoms (specifically,
Silica fine particles (treated with tildichlorosilane, etc.)
JP-A-55-120041 discloses trimethylsilo.
Silica fine particles treated with a xyl group are disclosed in
Japanese Patent No. 32,575 discloses that a saturated metal having 5 or more carbon atoms is used.
Or unsaturated aliphatic organic groups or at least one hydrocarbon
Having an organic group having an elementary ring and having 8 or more carbon atoms (component
Physically, it was treated with dihexyldichlorosilane etc.)
Silica fine particles are disclosed in JP-A-4-231318.
Treated with fluorine-containing silane coupling agent (specific
Typically, CHF₂-CF₂-O- (CH) ₂-Si-
(OCH₃)₃Etc.) Silica fine particles are disclosed. I
However, these silica fine particles are added to the toner as an external additive.
Even when added, fog is high, especially under high temperature and high humidity.
Could not obtain enough images.

On the other hand, JP-A-59-45457 discloses that after treatment with a silane coupling agent (specifically, γ-aminopropyltriethoxysilane), a silicone oil (specifically, dimethyl silicone) is added. Oil) treated with silica fine particles described in JP-A-61-2779.
No. 64 discloses silica fine particles having a degree of hydrophobicity of 90% or more treated with silicone oil (specifically, dimethyl silicone oil or the like). However, although a certain improvement effect on fog can be seen, as the number of printed sheets increases, the effect of suppressing the occurrence of fog decreases, and the image quality deteriorates.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner which is free from fog and can provide a high print density image in various environments, especially under high temperature and high humidity. Is to do.

[0007]

Means for Solving the Problems The present inventor has made intensive studies to achieve this object, and as a result, has a specific range of particle size, a specific particle size, and a small amount of siloxane compounds extracted with tetrahydrofuran. It was found that the above object was achieved by using silica fine particles treated with a siloxane compound as an external additive, and the present invention was completed based on this finding.

Thus, according to the present invention, there is provided (1) a siloxane containing colored particles and an external additive, wherein the external additive has a number average particle diameter of primary particles of 5 to 30 nm and is extracted with tetrahydrofuran. Silica fine particles (A) having a compound amount of 1% by weight or less and subjected to a hydrophobic treatment with a siloxane compound.
An electrostatic image developing toner, characterized by containing
(2) A siloxane containing colored particles and an external additive, wherein the external additive has a number average particle diameter of primary particles of 5 to 30 nm and an amount of a siloxane compound extracted with tetrahydrofuran is 1% by weight or less. Silica fine particles (A) hydrophobized with a compound, and number average particle diameter of primary particles of 30 to 10
An electrostatic image developing toner containing 0 nm silica fine particles (B); (3) containing colored particles and an external additive, wherein the external additive has a number average particle diameter of primary particles of 5 to 30 nm.
Containing silica fine particles (A) hydrophobized with a siloxane compound, wherein the amount of the siloxane compound extracted with tetrahydrofuran is 1% by weight or less, and organic fine particles having an average particle size of 0.1 to 0.5 μm. And (4) a colored particle and an external additive, wherein the external additive has a number average particle diameter of primary particles of 5 to 30.
silica fine particles (A) hydrophobically treated with a siloxane compound and having a number average particle size of 30 to 100 nm (B), wherein the amount of the siloxane compound extracted with tetrahydrofuran is 1% by weight or less. And (5) the colored particles have an area of a circle having a diameter corresponding to the absolute maximum length of the particles (Sc). ) Divided by the effective projected area (Sr) of the particles (sphericity (Sc
/ Sr)) is a core / shell particle having 1 to 1.3, wherein the electrostatic image developing toner according to (1) to (4) is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The electrostatic image developing toner of the present invention contains colored particles and an external additive. The colored particles contain a colorant and a binder resin.

The colored particles used in the present invention include, for example,
In a thermoplastic resin as a binder resin component, a colorant, a charge control agent, a release agent, and the like are melt-mixed and uniformly dispersed to form a composition, and then the composition is pulverized and colored by classification. A pulverization method for obtaining particles, a colorant, a charge controlling agent, a releasing agent or the like is dissolved or dispersed in a polymerizable monomer as a binder resin raw material, and after adding a polymerization initiator, a dispersion stabilizer is contained. It is suspended in an aqueous dispersion medium, heated to a predetermined temperature to start polymerization, and after the polymerization is completed, a suspension polymerization method for obtaining colored particles by filtration, washing, dehydration, and drying, or emulsion polymerization or suspension polymerization The particles obtained by aggregating the particles of the binder resin and the particles containing the colorant and the charge control agent by stirring at a temperature higher than the glass transition temperature of the binder resin are filtered and dried. An association method of obtaining colored particles by a hydrophilic group-containing resin as a binder resin, After adding a coloring agent and the like to dissolve it in an organic solvent, the resin is neutralized, phase inversion is performed, and then dried to obtain colored particles. It is preferable to use a toner obtained by a suspension polymerization method from the viewpoint of obtaining a toner that gives an image with good reproducibility. Further, the colored particles may have a capsule structure (hereinafter, sometimes referred to as a core-shell structure) obtained by combining different polymers.

[0011] 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.

Specific examples of the binder resin include resins widely used in toners, for example, polymers of styrene such as polystyrene, poly-p-chlorostyrene, and 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-chloromethacrylic acid Methyl copolymer, styrene-acrylonitrile copolymer, Len-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,
Phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins and the like can be mentioned, and these can be used alone or in combination.

As a preferred polymerizable monomer used for producing a binder resin, a monovinyl monomer can be used. Specifically, styrene, vinyl toluene,
Aromatic vinyl monomers such as α-methylstyrene; acrylic acid, methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, isobonyl acrylate, methacrylic Cyclohexyl acrylate, isobonyl methacrylate, dimethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methacrylic acid 2
-Derivatives of acrylic acid or methacrylic acid such as ethylhexyl, dimethylaminoethyl methacrylate, acrylamide, methacrylamide; ethylene, propylene,
Monoolefin monomers such as butylene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone and methyl isopropenyl ketone; 2-vinylpyridine; Vinyl pyridine,
Monovinyl monomers such as nitrogen-containing vinyl compounds such as N-vinylpyrrolidone; Monovinyl monomer is
A single monomer may be used, 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.

In producing the binder resin, 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; 1,4-butanediol, 1,9 -(Meth) acrylates derived from aliphatic both terminal alcohols such as nonanediol; N, N-
Other divinyl compounds such as divinylaniline and divinyl ether; compounds having three or more vinyl groups; The crosslinkable polymer is a polymer having two or more vinyl groups in the polymer, and specifically, a polymer having two or more hydroxyl groups in the molecule (a hydroxyl group-containing polyethylene, a hydroxyl group-containing polypropylene, Polyethylene glycol, polypropylene glycol, etc.)
And esters with ethylenically unsaturated carboxylic acids such as acrylic acid and methacrylic acid. 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.

The polymerization initiator used for producing the binder resin includes 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-hydroxyethylpropionamide, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (1 -Cyclohexanecarbonitrile) and the like; 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-ethylhexanoate, t- Butylperoxypivalate, t-hexylperoxypivalate, di-isopropylperoxydicarbonate, di-t-butylperoxyisophthalate, 1,1 ′, 3,3′-tetramethylbutylperoxy-2- Peroxides such as ethylhexanoate and t-butylperoxyisobutyrate 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 which is 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. In producing the binder resin, a molecular weight modifier and the like can be further added.

As the colorant contained in the colored particles, any pigment and / or dye can be used in addition to carbon black and titanium white. A black carbon black having a primary particle size of 20 to 40 nm is used. If it is less than 20 nm, dispersion of carbon black cannot be obtained, resulting in a toner with much fog. On the other hand, 40 nm
If it is larger, the amount of the polyvalent aromatic hydrocarbon compound increases, which may cause environmental safety problems.

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.

In order to improve the performance of the toner, a releasing agent or a negatively chargeable charge control agent can be 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 oxidized polypropylene, and low-molecular-weight terminal-modified polypropylene having a molecular terminal substituted with an epoxy group. And terminal-modified polyolefin waxes such as block copolymers of these and low-molecular-weight polyethylene, molecular-end-oxidized low-molecular-weight polyethylene, low-molecular-weight polyethylene having a molecular terminal substituted by an epoxy group, 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; mineral waxes equal pentaerythritol myristate, pentaerythritol monopalmitate, polyfunctional ester compounds such as dipentaerythritol hexa myristate and the like are being mentioned. These can be used alone or in combination of two or more.

Of these, synthetic waxes (particularly Fischer-Tropsch wax), terminal-modified polyolefin waxes, petroleum waxes, and polyfunctional ester compounds are preferred. Among the polyfunctional ester compounds, in a DSC curve measured by a differential scanning calorimeter, the endothermic peak temperature at the time of temperature rise is 30 to 200 ° C, preferably 40 to 200 ° C.
Polyester compounds such as pentaerythritol ester having a temperature in the range of 160 ° C., more preferably in the range of 50 to 120 ° C., and dipentaerythritol ester having the endothermic peak temperature in the range of 50 to 80 ° C., are fixed and released as toner It is particularly preferable from the viewpoint of the balance of properties. Among them, it has a molecular weight of 1,000 or more, dissolves at least 5 parts by weight at 25 ° C. in 100 parts by weight of styrene, and has an acid value of 10 mg / KO
Those having a value of H or less are more preferable because they have a remarkable effect on lowering the fixing temperature. The endothermic peak temperature is ASTM D341
It is the value measured by 8-82. The release agent,
It is used in an amount of 0.5 to 50 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the binder resin or the polymerizable monomer used to obtain the binder resin.

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.), Spiron Black TRH (Hodogaya Chemical Co., Ltd.), T-77 (Hodogaya Chemical Co., Ltd.), Bontron S-34 (Orient Chemical Co., Ltd.), Bontron E-8
1 (manufactured by Orient Chemical), Bontron E-84 (manufactured by Orient Chemical), Bontron E-89 (manufactured by Orient Chemical), Bontron F-21 (manufactured by Orient Chemical), COPY CHRGE NX (manufactured by Clariant), COPY CHRGE NEG (Clariant), TNS-4-1 (Hodogaya Chemical), TNS
Charge control agents such as -4-2 (Hodogaya Chemical Co., Ltd.) and LR-147 (Nippon Carlit Co., Ltd.);
No. 2, JP-A-3-175456, JP-A-3-175
Copolymers containing quaternary ammonium (salt) groups described in JP-A-243954, JP-A-3-243954, JP-A-1-217664, JP-A-3-158.
A charge control agent (charge control resin) such as a sulfonic acid (salt) group-containing copolymer described in JP-A-58-58, etc. 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 0.01 to 10 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the binder resin or the polymerizable monomer.
It is used in a proportion of 7 parts by weight.

The colored particles may contain a magnetic material. The materials used in this case are magnetite, γ
Iron oxides such as iron oxides, ferrites, and iron-rich ferrites; metals such as iron, cobalt, and nickel; or these metals and aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth,
Cadmium, calcium, manganese, selenium, titanium,
Examples include alloys with metals such as tungsten and vanadium, and mixtures thereof.

The production by the polymerization method is usually carried out by a suspension polymerization method,
It is performed by an emulsion polymerization method, a dispersion polymerization method, or the like. In order to stably perform the polymerization, a dispersion stabilizer can be added to the reaction solution. 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; Metal compounds and metal hydroxides such as aluminum hydroxide, magnesium hydroxide and ferric hydroxide; water-soluble polymers such as polyvinyl alcohol, methylcellulose and gelatin; anionic surfactants, nonionic surfactants and amphoteric Surfactants and the like can be mentioned. Among them, a dispersion stabilizer containing a metal compound, particularly a colloid of a sparingly water-soluble metal hydroxide, can narrow the particle size distribution of the polymer particles, and the persistence of the dispersant after washing is low. This is preferable because the influence of the image is small and the bad influence of the image is small.

The dispersion stabilizer containing a colloid of a poorly water-soluble metal hydroxide is not limited by its production method, but the poorly water-soluble polyhydric metal compound obtained by adjusting the pH of an aqueous solution of a polyvalent metal compound to 7 or more can be used. Colloidal metal hydroxide,
In particular, it is preferable to use a colloid of a poorly water-soluble metal hydroxide formed by a reaction of a water-soluble polyvalent metal compound and an alkali metal hydroxide in an aqueous phase. The reaction ratio between the water-soluble polyvalent metal salt and the alkali metal hydroxide is such that the chemical equivalent ratio A of the alkali metal hydroxide to the water-soluble polyvalent metal salt is in the range of 0.4 ≦ A ≦ 1.0.

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 generally used in a proportion of 0.1 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer. If this ratio is too low, agglomerates of polymer particles are likely to be formed. Conversely, if this ratio is too high, the distribution of toner particle diameters is widened, and the classification reduces the yield.

The colored particles can be particles having a structure obtained by combining two different polymers inside (core layer) and outside (shell layer) of the particles, so-called core-shell structure (also called capsule structure). In the core-shell structure particles, the balance between the lowering of the fixing temperature and the prevention of agglomeration during storage can be achieved by encapsulating the material having a lower softening point inside (core layer) with a material having a higher softening point. It is preferred. The colored particles having a core-shell structure may be obtained by a pulverization method, or may be obtained by a suspension polymerization method or an emulsion polymerization method.

In the case of core-shell particles, the volume average particle size of the core particles is not particularly limited, but is usually 2 to 10 μm, preferably 2 to 9 μm, more preferably 3 to 8 μm.
The volume average particle diameter (dv) / number average particle diameter (dp) is not particularly limited either, but is usually 1.7 or less, preferably 1.
5 or less, more preferably 1.3 or less.

The weight ratio of the core layer to the shell layer of the core-shell particles is not particularly limited, but is usually 80/20 to 99.
Used at 9 / 0.1. When the ratio of the shell layer is smaller than the above ratio, the storage stability is deteriorated. On the other hand, when the ratio is larger than the above ratio, fixing at a low temperature may be difficult.

The average thickness of the shell layer of the core-shell particles is as follows:
Usually 0.001 to 1.0 μm, preferably 0.003 to
It is 0.5 μm, more preferably 0.005 to 0.2 μm. When the thickness is large, the fixability is reduced, and when the thickness is small, the storability may be reduced. Note that the core particles forming the colored particles having the core-shell structure do not need to be entirely covered with the shell layer, and only a part of the surface of the core particles may be covered with the shell layer. When the core particle diameter of the core-shell particles and the thickness of the shell layer can be observed by an electron microscope, it can be obtained by directly measuring the size and the shell thickness of the particles randomly selected from the observation photograph. When it is difficult to observe the core and the shell, it can be calculated from the particle size of the core particles and the amount of the monomer forming the shell used in producing the toner.

The method for producing the core-shell particles is as follows.
Methods such as a spray drying method, an interface reaction method, an in situ polymerization method, and a phase separation method can be adopted. In particular, an in situ polymerization method or a phase separation method is preferable from the viewpoint of production efficiency.

A method for producing a capsule toner by an in situ polymerization method will be described below. In an aqueous dispersion medium containing a dispersion stabilizer, a polymerizable monomer composition containing at least a polymerizable monomer (core-use polymerizable monomer), a colorant, and the above-described release agent according to the present invention. The product (monomer composition for core) is suspended and polymerized using a polymerization initiator to produce core particles. Further, a polymerizable monomer (single monomer for shell) for forming a shell is prepared. ) And a polymerization initiator, followed by polymerization to obtain a capsule toner. The core particles can be obtained in the same manner as the toner obtained by the above-mentioned suspension polymerization method.

As the core monomer, the same as the above-mentioned polymerizable monomers can be exemplified. Above all, the glass transition temperature is usually 60 ° C or lower, preferably 40 to 60 ° C.
Those which can form a polymer at ℃ are suitable as the core monomer. 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.

In the case of a capsule toner, the volume average particle size of the core particles is usually 2 to 10 μm, preferably 2 to 9 μm,
More preferably, it is 3 to 8 μm. The ratio of volume average particle diameter (dv) / number average particle diameter (dp) is usually 1.7 or less, preferably 1.5 or less, and 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 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 pump such as a plunger pump.

The monomer for shell desirably provides 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, styrene, acrylonitrile, methyl methacrylate and the like have a glass transition temperature of 8
Monomers that form polymers having a temperature exceeding 0 ° C. can be used alone or in combination of two or more. 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 by the shell monomer is to improve the storage stability of the polymerized toner.
Usually, it is 50 to 130 ° C, preferably 60 to 120 ° C, more preferably 80 to 110 ° C. 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 is usually 10 ° C. or more, preferably 2 ° C.
The temperature is 0 ° C or higher, more preferably 30 ° C or higher.

When the shell monomer 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.

The external additive used in the present invention is a siloxane compound wherein the external additive has a number average particle size of primary particles of 5 to 30 nm and the amount of the siloxane compound extracted with tetrahydrofuran is 1% by weight or less. It contains silica fine particles (A) that have been subjected to a hydrophobic treatment.

The preferred average particle size of the primary particles of the silica fine particles (A) subjected to the hydrophobic treatment with the siloxane compound is 5 to 2
It is 5 nm, more preferably 5 to 20 nm. If the number average particle size of the primary particles is small, the fluidity becomes too good, and fogging is likely to occur. Conversely, if the number average particle size is large, the fluidity is deteriorated and fuzziness is liable to occur. The amount of the siloxane compound extracted with tetrahydrofuran is 1% by weight or less, preferably 0.5% by weight. If the amount of the siloxane compound to be extracted is more than 1% by weight, fogging tends to occur.
The amount of extraction was determined by the method described below.

The silica fine particles (A) have a degree of hydrophobicity of usually 30 to 90%, preferably 40 to 80%, as measured by a method called a methanol method. If the degree of hydrophobicity is small, the influence of the environment is great, and fogging may easily occur particularly under high temperature and high humidity conditions.

As the silica fine particles (A) which have been hydrophobized with a siloxane compound used in the present invention, commercially available silica fine particles can be used. For example, the method described in JP-A-7-330324, specifically, Is a non-volatile polydimethylsiloxane (silylating agent) end-blocked with trimethylsiloxy groups on silicic acid (silica) obtained by a pyrolysis method.
Is mixed in the form of a liquid, finely sprayed aerosol,
After stirring at 80 ° C. for 15 minutes, 1 hour at 300 ° C. in a dryer.
It can be obtained by purifying for 20 minutes while flowing a slight amount of nitrogen. It is not clear why the use of silica fine particles treated by this method as an external additive improves fog, but it is probably possible to bring such a specific siloxane compound into specific reaction conditions, The highly water-absorbing silanol groups present on the surface of the silica fine particles react efficiently with the silylating agent (chemically fixed), and the siloxane groups are introduced to increase the hydrophobicity. ), It is estimated that fog can be improved.

The amount of the silica fine particles (A) to be added is usually 0.1 to 3.0 parts by weight, preferably 0.2 to 2.0 parts by weight, per 100 parts by weight of the colored particles. If the addition amount is small, the fluidity is reduced, and scumming is apt to occur. Conversely, if the addition amount is large, the fluidity is too good and fog is liable to occur.

In the present invention, it is preferable that the silica fine particles (B) are contained in the external additive. The number average particle size of the primary particles is usually 30 to 100 nm, preferably 30 to 60 n.
m, more preferably 30 to 50 nm. When the number average particle diameter of the primary particles is small, the polishing effect is reduced, and the occurrence of filming cannot be suppressed. Conversely, when the number average particle size is large, the fluidity is deteriorated and fuzz is likely to occur.

The silica fine particles (B), like the silica fine particles (A), have a degree of hydrophobicity measured by a methanol method of usually 30 to 90%, preferably 40 to 80%. If the degree of hydrophobicity is small, the influence of the environment is great, and fogging may easily occur particularly under high temperature and high humidity conditions. The silica fine particles (B) subjected to the hydrophobic treatment are not particularly limited, but it is preferable to use those treated with a silane coupling agent or a siloxane compound.

The amount of the silica fine particles (B) to be added is usually 0.05 to 1.0 part by weight, based on 100 parts by weight of the colored particles.
Preferably, 0.1 to 0.5 part by weight is used. If the amount is small, the polishing effect is small, and it is not possible to suppress the occurrence of filming. On the other hand, if the amount is large, the fluidity is deteriorated and fuzz is easily generated.

The external additive of the present invention preferably contains organic fine particles, and the number average particle diameter is usually 0.1 to 0.8 μm, preferably 0.2 to 0.6 μm. If the number average particle size is small, filming may not be prevented, whereas if it is large, the fluidity may be reduced.

Although the glass transition temperature of the organic fine particles is not particularly limited, the compound constituting the fine particles generally has a glass transition temperature of 60 to 250 ° C., preferably 80 to 200 ° C., from the viewpoint of suppressing blocking between the particles. is there.
As a compound constituting the organic fine particles, acrylate polymer, methacrylate polymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, urethane polymer, polyamide polymer,
Examples thereof include a vinyl chloride polymer, a vinylidene chloride polymer, and cellulose. Among these, a methacrylate polymer and a styrene-methacrylate copolymer are preferable. Specific examples include a methyl methacrylate polymer and a styrene-methyl methacrylate copolymer, and core-shell particles having a styrene polymer as a core and a methacrylate copolymer as a shell are preferable.

The addition amount of the organic fine particles is not particularly limited, but is usually 0.05 to 1 based on 100 parts by weight of the colored particles.
Parts by weight, preferably 0.1 to 0.5 parts by weight. If the amount is small, filming is likely to occur, and if the amount is large, the fluidity is deteriorated and the film is likely to be worn.

In the present invention, inorganic fine particles can be added as external additives in addition to the above-mentioned silica fine particles and organic fine particles. Examples of the inorganic fine particles include titanium oxide, aluminum oxide, zinc oxide, tin oxide, barium titanate, strontium titanate, and the like. These are 20% by weight or less, preferably 10% by weight or less of the total amount of external additives. Can be used in combination.

The toner for electrophotographic development of the present invention can be obtained by mixing the colored particles and the external additive with a high-speed stirrer such as a Henschel mixer.

[0057]

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. In the present example, evaluation was made by the following method.

[Evaluation Method] (Volume Average Particle Size and Particle Size Distribution) The volume average particle size (dv) of the colored particles and the particle size distribution, ie, the ratio (dv / d) of the volume average particle size to the number average particle size (dp). dp) was measured with a Multisizer (manufactured by Beckman Coulter). The measurement with this multisizer was performed with an aperture diameter of 100 μm.
m, medium: Isoton II, concentration 10%, number of measured particles:
The test was performed under the condition of 100,000 pieces. (Number average particle diameter) The number average particle diameter of silica and organic fine particles was determined by taking an electron micrograph of each particle and photographing the photograph with an image processing analyzer Luzex IID (manufactured by Nireco Corporation). Area ratio: up to 2%
The circle equivalent diameter was calculated under the condition of the total number of treated particles: 100, and the average value was calculated.

(Sphericity) The sphericity (Sc / Sr) of the value obtained by dividing the area (Sc) of a circle whose diameter is the absolute maximum length of a particle by the actual projected area (Sr) of the particle is represented by an electron microscope. A photograph is taken, and the photograph is taken by an image processing / analysis apparatus Luzex IID (manufactured by Nireco Co., Ltd.).
It is an average value of 100 measured and calculated on 0 conditions.

(Degree of Hydrophobicity) The degree of hydrophobicity by the methanol method is determined according to the following measuring method. 0.2 g of the treated inorganic fine particles were weighed into a 500 ml beaker, and purified water 5
Add 0 ml, and add methanol below the liquid level while stirring with a magnetic stirrer. The point at which no sample is observed on the liquid surface is defined as the end point, and the degree of hydrophobicity is calculated by the following equation. Degree of hydrophobicity (%) = (X / (50 + X)) × 100 X; Methanol usage (ml) (THF extraction) 25 g of silica fine particles were put in 100 g of tetrahydrofuran (THF), and stirred and ultrasonically treated. Thereafter, the filtrate is collected by pressure filtration. The silicon compound content was measured by atomic absorption analysis of the filtrate. On the other hand, the filtrate is concentrated 10 times with a rotary evaporator, and the content of the siloxane compound is measured using gas chromatography. From the content of the siloxane compound, the ratio to the silica fine particles used as the sample is calculated.

(Fog) Copy paper is set in a commercially available non-magnetic one-component developing system printer (20 sheets), and a developer to be evaluated is put in a developing device of the printer. (N / N) environment, temperature (35 ° C.) and humidity 80% (H / H) environment, temperature 10 ° C. and humidity 2
5% after standing all day and night under each environment of 0% (L / L) environment
Continuous printing is performed at the print density, printing is stopped halfway after the initial printing (when printing 10 sheets) and after printing 30,000 sheets, and the toner in the non-image area on the photoreceptor after development is adhered to an adhesive tape (Sumitomo 3M Co., Ltd.). Scotch Mending Tape 810-3-1
8). It was attached to a printing paper, and its whiteness (B) was measured with a whiteness meter (manufactured by Nippon Denshoku). Similarly, only the adhesive tape was stuck on the printing paper, and its whiteness (A) was measured. The fog value is expressed as fog (%) = (A−
It was calculated by the calculation formula of B). A smaller value indicates less fog.

(Outline of Commercially Used Silica Used) Silica-A1 Hydrophobized with octamethylcyclotetrasiloxane, primary particle size: 14 nm, degree of hydrophobicity: 75%, amount of siloxane compound extracted by THF: 0.1% Silica (product name: R-104) manufactured by Nippon Aerosil Co., Ltd. Silica-A2 Silica manufactured by Nippon Aerosil Co., Ltd. having a primary particle diameter of 7 nm, a hydrophobicity of 65%, and a siloxane compound amount of 0.05% extracted with THF, which has been subjected to hydrophobic treatment with octamethylcyclotetrasiloxane (product name: R -106). Silica-B1 Hydrophobized with polydimethylsiloxane and hexamethyldisilazane, primary particle size 40 nm, hydrophobicity 77
%, The amount of siloxane compound extracted with THF is 0.08%
% Silica manufactured by Clariant (product name: HDK-H05)
TX). Silica-B2 Silica (trade name: RX50) manufactured by Nippon Aerosil Co., Ltd., having a primary particle size of 40 nm, a hydrophobicity of 67%, and a siloxane compound amount of 0% extracted with THF, having been subjected to hydrophobic treatment with hexamethyldisilazane. Silica-C1 Silica (trade name: RX300) manufactured by Nippon Aerosil Co., Ltd., having a primary particle diameter of 7 nm, a hydrophobicity of 67%, and a siloxane compound amount of 0% extracted with THF, having been subjected to hydrophobic treatment with hexamethyldisilazane. Silica-C2 Hydrophobized with silicone oil, primary particle size 14n
m, a degree of hydrophobicity of 64%, and a siloxane compound amount extracted with THF of 2.6%, silica manufactured by Degussa (product name: R-2).
02).

REFERENCE EXAMPLE 1 100 parts of styrene, 2.5 parts of sodium styrenesulfonate, 1.5 parts of sodium chloride and 4000 parts of ion-exchanged water were added to a nitrogen-replaced reaction vessel equipped with a stirrer and mixed. To 80 ° C. After heating, 2,2'-azobis [2-methyl-N-
(2-Hydroxyethyl) propionamide] (trade name: "VA-80", manufactured by Wako Pure Chemical Industries, Ltd.) 3% aqueous solution 50
0 parts were added to initiate the polymerization. On the way, while measuring the polymerization conversion, when the conversion reached 30%, 0.1 part of t-dodecyl mercaptan was added, and the conversion was measured 7 hours after the start of the polymerization, and was 98%. Next, 400 parts of methyl methacrylate was added over 15 minutes, and further 3 parts were added.
After the polymerization was continued for a period of time, the polymerization was stopped by cooling with water to obtain an aqueous dispersion of core-shell type organic fine particles. At this time, the polymerization conversion was 97%, and the number average particle diameter of the organic fine particles was 0.3.
8 μm, sphericity was 1.13.

(Example 1) 83 parts of styrene, 17 parts of n-butyl acrylate, carbon black (trade name "# 2
5B ", manufactured by Mitsubishi Chemical Corporation; primary particle size: 40 nm) 6 parts, charge control agent (trade name:" Spiron Black TRH ", manufactured by Hodogaya Chemical Co., Ltd.) 0.5 parts, divinylbenzene 0.6 parts, t-
One part of dodecyl mercaptan and two parts of Sasol wax (trade name “Paraflint Spray 30”, manufactured by Sasol) were dispersed at room temperature by a bead mill to obtain a uniform mixed solution. While stirring the mixture, the polymerization initiator t-
Butyl peroxy 2-ethylhexanoate (trade name;
5 parts of "Perbutyl O" (manufactured by NOF Corporation) were added, and stirring was continued until the droplets became uniform.

On the other hand, 4.8 parts of sodium hydroxide (alkali metal hydroxide) was added to 50 parts of ion-exchanged water 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. 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 polymer particles obtained as described above, sulfuric acid was added to adjust the pH to 4 or less, 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, volume average particle diameter (dv) / number average particle diameter (dp), which is an index of particle diameter distribution, was 1.25, and sphericity was 1.15.

Hydrophobic treatment with 100 parts of the obtained colored particles and octamethylcyclotetrasiloxane having a number average particle diameter of primary particles of 14 nm, a degree of hydrophobicity of 75%, and an amount of siloxane compound extracted with tetrahydrofuran of 0.1%. 0.5 parts of the prepared silica fine particles A1 (trade name “R-104”, manufactured by Nippon Aerosil Co., Ltd.) and the number average particle diameter of primary particles 40 n
m, silica fine particles B1 having a hydrophobicity of 77% (trade name “HD
(K-h05TX, Clariant) 2.0 parts and the organic fine particles 0.5 part obtained in Reference Example 1 were mixed with a Henschel mixer for 10 minutes at a rotation speed of 1400 rpm,
An electrostatic image developing toner was obtained. About the obtained toner,
Print evaluation was performed. Table 1 shows the results.

[0068]

[Table 1]

(Examples 2 and 3, Comparative Examples 1 and 2) Evaluations were made in the same manner as in Example 1 except that the external additives were changed as shown in Table 1. Table 1 shows the results.

From the evaluation results of the toners in Table 1, the following can be understood. The toner of Comparative Example 1 using silica fine particles hydrophobized with hexamethyldisilazane as an external additive is:
Fog is likely to occur. Although the external additive is subjected to a hydrophobic treatment with a siloxane compound, the toner of Comparative Example 2 using silica fine particles in which the amount of the siloxane compound extracted with tetrahydrofuran is more than 1% by weight tends to cause fog. In contrast, it can be seen that the toners of Examples 1 to 3 of the present invention hardly cause fogging even when the number of printed sheets increases.

[0071]

According to the present invention, there is no fog even when the number of printed sheets is increased in various environments, especially under high temperature and high humidity.
Provided is a toner capable of obtaining an image having a high print density.

Claims (5)

[Claims] Claims: 1. An external additive comprising colored particles and an external additive, wherein the external additive has a number average particle size of primary particles of 5 to 30 nm and an amount of a siloxane compound extracted with tetrahydrofuran is 1
An electrostatic image developing toner comprising, by weight or less, silica fine particles (A) hydrophobically treated with a siloxane compound. 2. The method according to claim 1, wherein the colorant contains an external additive, the external additive has a number average particle diameter of primary particles of 5 to 30 nm, and the amount of the siloxane compound extracted with tetrahydrofuran is 1
Weight% or less, silica fine particles (A) hydrophobized with a siloxane compound, and number average particle diameter of primary particles 3
An electrostatic image developing toner containing silica fine particles (B) of 0 to 100 nm. 3. The method according to claim 1, further comprising a coloring particle and an external additive, wherein the external additive has a number average particle diameter of primary particles of 5 to 30 nm, and an amount of the siloxane compound extracted with tetrahydrofuran is 1 to 3.
Weight% or less, silica fine particles (A) hydrophobized with a siloxane compound, and an average particle size of 0.1 to 0.5 μm
m. An electrostatic image developing toner containing m. organic fine particles. 4. It contains colored particles and an external additive, wherein the external additive has a primary particle number average particle size of 5 to 30 nm, and the amount of the siloxane compound extracted with tetrahydrofuran is 1
% By weight or less, silica fine particles (A) hydrophobized with a siloxane compound, number average particle diameter of primary particles 30 to
100 nm silica fine particles (B) and an average particle size of 0.1 to 0.1
An electrostatic image developing toner containing 0.5 μm of organic fine particles. 5. A value (sphericity (Sc / Sr)) obtained by dividing the area (Sc) of a circle of the colored particles whose diameter is the absolute maximum length of the particles by the substantial projected area (Sr) of the particles is 1 to 1. 3. Core / shell particles having a particle size of 0.3 to 3.
An electrostatic image developing toner as described in the above.