JP2002182423A - Toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner giving an excellent image even on recycled paper. SOLUTION: Organic fine particles having 0.05-1 μm average particle diameter, spherical fine silica particles having 0.03-1 μm average particle diameter and inorganic fine particles having 5-40 nm average particle diameter made hydrophobic by treatment with a siloxane compound are added as additives to colored particles.

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 pulverizing method toner that obtains colored particles by classification, or a colorant, a charge control agent, a releasing agent or the like in a polymerizable monomer that is a binder resin raw material is dissolved or dispersed, and after adding a polymerization initiator, Polymerized toners are generally used, which are heated to a polymerization temperature, and after polymerization, are filtered, washed, dehydrated, and dried to obtain colored particles. By this method, it is possible to produce a toner having excellent properties to some extent, but it is necessary to obtain a higher image quality and to provide a stable image even in a poor environment such as high temperature, high humidity and low temperature and low humidity. The demand is only growing.

[0003] In response to such demands, proposals have been made to cope with the design of a binder resin and to include functional components such as a charge control agent and a release agent in the colored particles. Alternatively, there is a proposal to improve the image quality of the toner by adding an external additive represented by inorganic fine particles. For example, JP-A-6-194864 discloses that by using silica fine particles and organic fine particles together as an external additive, sufficient flowability and chargeability of the polymerized toner can be ensured and good image quality can be obtained. Has been disclosed. Japanese Patent Application Laid-Open No. 4-186251 discloses a flow improver such as titanium oxide or alumina, organic fine particles, and a weight average particle size of 0.2 to 2.5 as external additives.
It has been proposed to use a silicon-containing compound of μm.
In the examples of the publication, a two-component toner obtained by adding such a three-component external additive to a polyester-based pulverized toner obtains a color image using an organic semiconductor (OPC) photoconductor by an electrophotographic method. In this case, it has been shown that continuous printing of clear images is possible without damaging the photoreceptor. Also, in JP-A-11-327194,
Particle size 20-50n as external additive to non-magnetic pulverized toner
It has been reported that a good image quality can be formed even when there is a change in temperature or humidity when a spherical oxide fine particle such as silica or titanium oxide having a particle diameter of m and a spherical oxide fine particle having a particle diameter of 50 to 300 nm are used in combination. I have.

[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 It is an object of the present invention to provide a high print quality without fogging, blurring, filming, etc., even when recycled paper is used as a transfer material and continuous printing is performed for a long time in various environments. It is an object of the present invention to provide a toner capable of obtaining an image having a high density, in particular, a toner which does not generate fogging during replenishment.

[0006]

Means for Solving the Problems The present inventor has conducted intensive studies to achieve this object. As a result, organic fine particles and silica fine particles having a specific particle size, and inorganic fine particles having a specific particle size treated with a siloxane compound have been obtained. It has been found that the above object is achieved by using an external additive containing, and the present invention has been completed based on this finding. Thus, according to the present invention, there is provided a toner comprising at least colored particles and an external additive, wherein the external additive comprises organic fine particles having an average particle size of 0.05 to 1 μm and organic fine particles having an average particle size of 0.03 to 1 μm. A toner characterized by containing spherical silica fine particles and inorganic fine particles having an average particle diameter of 5 to 40 nm subjected to a hydrophobic treatment with a siloxane compound 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 comprises at least colored particles and an external additive.

The colored particles used in the present invention contain a colorant and a binder resin. For example, a colorant, a charge control agent, a release agent, etc. are contained in a thermoplastic resin as a binder resin component. After melt-mixing and uniformly dispersing the composition into a composition, the composition is pulverized, a pulverization method of obtaining colored particles by classifying, a coloring agent in a polymerizable monomer as a binder resin raw material, a charge, Control agent, dissolve or disperse the release agent, etc., after adding the polymerization initiator, suspended in an aqueous dispersion medium containing a dispersion stabilizer, heated to a predetermined temperature to start polymerization, after the polymerization is completed A polymerization method of obtaining colored particles by filtration, washing, dehydration, and drying, binding of particles of a binder resin obtained by emulsion polymerization or suspension polymerization, and particles containing a colorant and a charge control agent, The particles associated by stirring at a temperature higher than the glass transition temperature of the resin are filtered. Association method to obtain the colored particles by drying, a hydrophilic group-containing resin as a binder resin,
It can be produced by a phase inversion emulsification method or the like in which a colorant or the like is added and dissolved in an organic solvent, and then the resin is neutralized and phase inversion is carried out, followed by drying to obtain colored particles.
It is preferable to use a toner obtained by a polymerization method from the viewpoint of obtaining a toner giving an image quality with good dot reproducibility. Further, the colored particles may have a capsule structure (hereinafter, sometimes referred to as a core-shell structure) obtained by combining different polymers.

Although the sphericity of the colored particles is not particularly limited, it is usually from 1 to 1.3. When the sphericity is in this range, the fluidity is improved, the developability is improved (the toner easily moves to the photoreceptor), and the transferability is improved (fogging is less likely to occur). The volume average particle size (dv) of the colored particles is 3 to 12 μm, preferably 4 to 10 μm.
And the ratio of the volume average particle diameter to the number average particle diameter (dn) (d
v / dn) is preferably in the range of 1 to 1.3. Here, the sphericity (Sc / Sr) referred to in the present invention is:
This is a value obtained by dividing the area (Sc) of a circle having the diameter based on the absolute maximum length of the particle by the substantial projected area (Sr) of the particle.

As the binder resin, resins widely used in toners such as polystyrene and polyp
-Styrene such as chlorostyrene and polyvinyltoluene and its 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 Styrene copolymers such as a copolymer, a styrene-butadiene copolymer, a styrene-isoprene copolymer, a styrene-acrylonitrile-indene copolymer, a styrene-maleic acid copolymer, and a 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 Resins, aromatic petroleum resins and the like can be used, and these can be used alone or in combination.

As a preferable 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 a binder resin, the use of a crosslinkable compound such as a crosslinkable monomer or a crosslinkable polymer together with a polymerizable monomer is effective in 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; N, N-divinylaniline, divinyl ether and the like And other divinyl compounds having two vinyl groups; pentaerythritol triallyl ether, trimethylolpropane triacrylate, and other 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 an ethylenically unsaturated carboxylic acid (eg, acrylic acid or 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.

Examples of the polymerization initiator used for producing the binder resin 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-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 soluble in the polymerizable monomer to be used, and if necessary, a water-soluble polymerization initiator may 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 other than carbon black and titanium white can be used. 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, 112, 11
4, 122, 123, 144, 146, 149, 16
3, 170, 184, 185, 187, 202, 20
6, 207, 209, 251, C.I. I. Pigment Violet 19 and the like. As the cyan colorant,
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, 1
5: 3, 15: 4, 16, 17, and 60, and the like. The amount of the colorant used is 1 to 10 parts by weight based on 100 parts by weight of the binder resin or the polymerizable monomer.

In order to improve the performance of the toner, a release agent, a charge control agent and the like can be added. As the release agent, for example, low molecular weight polyethylene, low molecular weight polypropylene,
Low molecular weight polyolefin waxes such as low molecular weight polybutylene, low molecular weight oxidized polypropylene with molecular terminal oxidation, low molecular weight terminal modified polypropylene in which the molecular terminal is substituted with an epoxy group and block polymers of these and low molecular weight polyethylene, molecular terminal oxidized low molecular weight polyethylene, molecular terminal -Modified polyolefin waxes such as low-molecular-weight polyethylenes substituted with an epoxy group and block polymers of these and low-molecular-weight polypropylene; natural plant-based waxes such as candelilla, carnauba, rice, wood wax, jojoba; paraffin, microcrystalline, petrolactam Petroleum waxes and modified waxes thereof; mineral waxes such as montan, ceresin and ozokerite; synthetic waxes such as Fischer-Tropsch wax; Lithol tetra myristate, pentaerythritol monopalmitate, such as a polyfunctional ester compounds such as dipentaerythritol hexa myristate and the like. These can be used alone or in combination of two or more.

These release agents have an endothermic peak temperature at the time of temperature rise in a DSC curve measured by a differential scanning calorimeter, usually 30 to 200 ° C., preferably 40 to 160 ° C. Among the release agents described above, synthetic waxes (particularly Fischer-Tropsch wax), terminal-modified polyolefin waxes, petroleum waxes, and polyfunctional ester compounds are preferred. Among these, polyfunctional ester compounds such as pentaerythritol ester having an endothermic peak temperature in the range of 50 to 120 ° C. and dipentaerythritol ester having the same end temperature in the range of 50 to 80 ° C. reduce the fixing temperature of the toner. It is more preferable because it can be set low and the toner hardly adheres to the fixing roll. Further, it has a molecular weight of 1000 or more, and styrene 1
5 parts by weight or more with respect to 00 parts by weight, acid value is 10 m
Those having a value of not more than g / KOH are particularly preferable because they have a remarkable effect on lowering the fixing temperature. The endothermic peak temperature is ASTM D
3418-82. The release agent is 0.5 to 50 parts by weight, based on 100 parts by weight of the binder resin or the polymerizable monomer used to obtain the binder resin.
Preferably, 1 to 20 parts by weight is used.

The charge controlling 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 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 these, the dispersion stabilizer containing a metal compound, particularly a colloid of a poorly water-soluble metal hydroxide, can narrow the particle size distribution of the polymer particles, and the residual amount of the dispersion stabilizer after washing. This is preferable since the influence on 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 the aqueous solution of the 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 represented by the chemical equivalent ratio of the alkali metal hydroxide to the water-soluble polyvalent metal salt.
Then, the range is 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 usually 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 may 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 between the core layer and 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 μm, preferably 0.003 to 0.
It is 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 (polymerizable monomer for a core), a colorant, and a release agent (a single monomer for a core) Body composition) is suspended and polymerized using a polymerization initiator to produce core particles,
Further, a polymerizable monomer for forming a shell (monomer for shell) and a polymerization initiator are added and polymerized 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.

Examples of the core monomer include the same as the above-mentioned polymerizable monomers. 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 selected from the above-mentioned monovinyl monomers or crosslinkable compounds, and one or more of them can be used in combination.

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 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 layer is formed by adding a shell monomer to the obtained core particles and polymerizing again. 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.

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.

In the present invention, the external additive has an average particle size of 0.05 to
It contains 1 μm organic fine particles, silica fine particles having an average particle size of 0.03 to 1 μm, and inorganic fine particles having an average particle size of 5 to 40 nm which have been hydrophobized with a siloxane compound.

The organic fine particles have a volume average particle size of 0.0
It is 5 to 1 μm, preferably 0.1 to 0.8 μm. The sphericity is not particularly limited, but is usually 1 to 1.3, preferably 1 to 1.2. If the volume average particle size is too small, the occurrence of filming may not be prevented, whereas if it is too large, the fluidity may decrease. When the sphericity is in this range, the fluidity is improved, the developability is improved (the toner easily moves to the photoreceptor), and the transferability is also improved (the fog hardly occurs).

Although the glass transition temperature of the organic fine particles is not particularly limited, the glass transition temperature of the compound constituting the fine particles is usually from 60 to 250 ° C., preferably from 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 methyl methacrylate polymer and styrene-methyl methacrylate copolymer, and among these, core-shell type particles in which the core is formed of a styrene polymer and the shell is formed of a methacrylate copolymer are preferable. .

The 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.

The silica fine particles have a volume average particle size of 0.1.
It is from 0.3 to 1 μm, preferably from 0.05 to 0.5 μm. The sphericity is not particularly limited, but is usually 1 to 1.3, preferably 1 to 1.2. If the volume average particle size is too small, the occurrence of filming may not be prevented, whereas if it is too large, the fluidity may decrease. When the sphericity is in this range, the fluidity is improved, the developability is improved (the toner easily moves to the photoreceptor), and the transferability is improved (fogging is less likely to occur).

The above silica fine particles have a degree of hydrophobicity, as measured by the methanol method, of usually 30 to 90%, preferably 50 to 80%. If the degree of hydrophobicity is small, the influence of the environment is large, and particularly, the charge may decrease under high temperature and high humidity, and fog may easily occur. May occur. The hydrophobization treatment can be performed by a known method, for example,
-5782, a method of treating with a silane compound having an organic group having 1 to 3 carbon atoms.
No. 1, the method of treating with a trimethylsiloxyl group; Japanese Unexamined Patent Publication (KOKAI) Showa No. 58-132775, a saturated or unsaturated aliphatic organic group having 5 or more carbon atoms or a carbon having at least one hydrocarbon ring. A method of treating with a silane compound having an organic group having 8 or more atoms can be given. In addition, the method of treating with a non-volatile polydimethylsiloxane (silylating agent) end-blocked with a trimethylsiloxy group described in JP-A-7-330324 suppresses the generation of fog even under high temperature and high humidity, and has a high efficiency. This is preferable because an image having a print density can be obtained.

The addition amount of the silica fine particles is not particularly limited, but is usually 0.05 to 1 with respect to 100 parts by weight of the colored particles.
Parts by weight, preferably 0.1 to 0.5 parts by weight. If the addition amount is small, the polishing effect is reduced, and the occurrence of filming cannot be suppressed. If the addition amount is large, the fluidity is deteriorated, and fuzziness may easily occur.

The inorganic fine particles hydrophobized with the siloxane compound used in the present invention have an average particle size of 5 to 40 nm,
Preferably it is 10 to 30 nm. The sphericity is not particularly limited, but is usually 1 to 1.3, preferably 1 to 1.
2, and the amount of the siloxane compound extracted with tetrahydrofuran is usually 1% by weight or less, preferably 0.5% by weight or less. If the average particle size is too small, the charge amount may increase at low temperature and low humidity and the printing density may decrease. Conversely, if the average particle size is too large, the charge amount may decrease at high temperature and high humidity and fog may increase. Further, when the sphericity is in this range, the fluidity is improved, the developability is improved (the toner easily moves to the photoreceptor), and the transferability is improved (fogging is less likely to occur). On the other hand, when the amount of the extracted siloxane compound is 1% by weight or less, generation of fog can be suppressed.
The amount of extraction was determined by the method described below.

As the inorganic fine particles which have been hydrophobized with the siloxane compound used in the present invention, commercially available inorganic fine particles can be used. For example, the method described in JP-A-7-330324, specifically, thermal decomposition The silicic acid (silica) obtained by the method is mixed with a non-volatile polydimethylsiloxane (silylating agent) end-blocked with a trimethylsiloxy group in the form of a liquid finely sprayed aerosol,
After stirring at 15 ° C for 15 minutes, 12 hours at 300 ° C in a dryer.
It can be obtained by purifying under a slight nitrogen flow for 0 minutes. In the siloxane compound used for the treatment, alkylcyclotetrasiloxane is preferable,
Among them, octamethylcyclotetrasiloxane is preferable. 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.

As such inorganic fine particles, for example,
Although silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, barium titanate, strontium titanate, and the like can be used, silica and titanium oxide are preferable in consideration of suppressing generation of fogging and blurring.

The inorganic fine particles usually have a degree of hydrophobicity of 30 to 90%, preferably 4 to 4, as measured by a method called a methanol method.
0 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 addition amount of the inorganic fine particles is not particularly limited, but is usually 0.05 to 1 with respect to 100 parts by weight of the colored particles.
Parts by weight, preferably 0.1 to 0.5 parts by weight. If the addition amount is small, the polishing effect is reduced, and the occurrence of filming cannot be suppressed, and if it is large, the flowability deteriorates,
Scratches are likely to occur.

The colored particles and the inorganic fine particles hydrophobically treated with the siloxane compound having an amount of 1% by weight or less of the siloxane compound extracted with the organic fine particles, the silica fine particles and the tetrahydrofuran as external additives are mixed with a Henschel mixer or the like. Mix with a high speed stirrer. At this time, it is preferable that the inorganic fine particles hydrophobically treated with the siloxane compound, in which the amount of the siloxane compound extracted with the organic fine particles, the silica fine particles and the tetrahydrofuran is 1% by weight or less, are previously crushed by a Henschel mixer or the like. , May be performed independently, or may be performed after mixing.

According to the image forming method of the present invention, the toner is adhered to the surface of the photoreceptor on which the electrostatic latent image is recorded to form a visible image, and the visible image is transferred to a transfer material to form an image. can do.

Hereinafter, the image forming method will be described in detail with reference to the drawings. Although the following description is for a non-magnetic one-component developing system, the image forming method of the present invention is not limited to this, and a magnetic one-component developing system, a non-magnetic two-component developing system, and a magnetic two-component developing system can be used. A method may be used. As shown in FIG. 1, a photosensitive drum 1 as a photosensitive member is mounted on the image forming apparatus so as to be rotatable in the direction of arrow A. The photosensitive drum 1 has a photoconductive layer provided on the outer peripheral surface of a conductive support drum. The photoconductive layer is made of, for example, an organic photoconductor, a selenium photoconductor, a zinc oxide photoconductor, an amorphous silicon photoconductor, or the like.

Around the photosensitive drum 1, along a circumferential direction thereof, a charging roll 3 as a charging unit, a laser beam irradiation device 4 as a latent image forming unit, a developing roll 7 as a developing unit, and a transfer roll as a transferring unit. A transfer roll 5 and a cleaning device (not shown) are provided.

The charging roll is for uniformly charging the surface of the photosensitive drum positively or negatively. By applying a voltage to the charging roll and bringing the charging roll into contact with the photosensitive drum, the surface of the photosensitive drum is charged. Is charged. The charging roll 3 can be replaced by charging means using corona discharge.

The laser beam irradiation device 4 irradiates the surface of the photosensitive drum with light corresponding to the image signal, and irradiates the uniformly charged surface of the photosensitive drum with light in a predetermined pattern.
The purpose is to form an electrostatic latent image on a portion irradiated with light (in the case of reversal development) or to form an electrostatic latent image on a portion not irradiated with light (in the case of regular development). As another latent image forming unit, there is a unit formed of an LED array and an optical system.

The developing roller is for applying toner to the electrostatic latent image on the photosensitive drum 1 to form a visible image.
In reversal development, toner is adhered only to the light irradiation part,
In normal development, a bias voltage is applied between the developing roll and the photosensitive drum so that the toner adheres only to the light non-irradiated portion.

A developing roll 7 and a supply roll 9 are provided in a developing device 11 in which the toner 10 is stored.
The developing roll is arranged close to and in contact with the photosensitive drum, and rotates in a direction B opposite to the photosensitive drum. The supply roll 9 contacts the development roll 7 and rotates in the same direction C as the development roll to supply toner to the outer periphery of the development roll. Normally, a voltage is also applied to the supply roll so that the toner can be supplied smoothly.

At a position between the point of contact with the supply roll and the point of contact with the photosensitive drum around the developing roll,
A developing roll blade 8 as a layer thickness regulating means is provided. This blade 8 is made of conductive rubber or stainless steel, and performs charge injection into toner.
A voltage of 200 V | to | 600 V | is applied. Therefore, the electrical resistivity of the blade 8 is 10 6 Ωcm.
The following is preferred.

The developing device 11 of the image forming apparatus contains the electrostatic image developing toner 10 described above. The transfer roll 5 is for transferring the toner image on the surface of the photosensitive drum formed by the developing roll to the transfer material 6. Examples of the transfer material include paper and OHP sheets. Examples of the transfer unit include a corona discharge device and a transfer belt in addition to the transfer roll.

The toner image transferred to the transfer material is fixed to the transfer material by the fixing unit 2. As fixing means,
Usually, it comprises a heating means and a pressure bonding means. The toner transferred to the transfer material is heated by heating means to melt the toner,
The melted toner is pressed and fixed to the surface of the transfer material by a pressing means.

The cleaning device is for cleaning the transfer residual toner remaining on the surface of the photosensitive drum.
For example, it is constituted by a cleaning blade or the like. Note that this cleaning device does not necessarily need to be installed when adopting a method of performing cleaning at the same time as development by the developing roll.

[0063]

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, that is, 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 substantial 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)

(Print Density and Fog) Recycled paper is set in a commercially available non-magnetic one-component developing system printer (12-sheet machine), and the toner to be evaluated in the developing device of the printer is 1
50g, left overnight in an environment of 23 ° C and 50% humidity (N / N), continuous printing was performed from the beginning at 5% printing density, and when the toner was reduced to about 50g, black solid printing was performed. The density and fog were measured. Next, a printing test was performed by adding 150 g of the toner,
A printing test was similarly performed with the number of sheets reduced to g. Further, 150 g of toner was added, and thereafter printing of 10,000 sheets was continued. Since about 5,000 sheets can be printed per 100 g of toner, 20,000 sheets were finally printed. During this time, 1
Black solid printing was performed every 000 sheets, and the print density and fog were examined. The print density was measured with a reflection densitometer (manufactured by Macbeth), and the fog was measured with a whiteness meter (manufactured by Nippon Denshoku) for fog in the non-image area of the photoconductor. Fog stops printing halfway, and after development, the toner in the non-image area on the photoreceptor is adhered to an adhesive tape (Scotch Mending Tape 810-3- manufactured by Sumitomo 3M Limited).
18). It was attached to a printing paper, and its whiteness (B) was measured. Similarly, only the adhesive tape was stuck on the printing paper, and its whiteness (A) was measured. The fog value was calculated by the following formula: fog (%) = (AB). A smaller value indicates less fog.
The replenishment fog was defined as the value at which the fog value became the maximum after two replenishments.

(Removal) A recycled paper is set in a commercially available non-magnetic one-component developing system printer (12-sheet machine), and a developer to be evaluated is put in a developing device of the printer.
After standing in a temperature and humidity (N / N) environment day and night, continuous printing was performed at a print density of 5%, and visual observation was performed every 500 sheets to count the number of sheets where blurring occurred. The final print number was 20,000 sheets. In the case where no number was described in the table, no blurring occurred even after continuous printing of 20,000 sheets.

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-086", manufactured by Wako Pure Chemical Industries) 3% aqueous solution 5
The polymerization was started by adding 00 parts. On the way, while measuring the polymerization conversion rate, when the conversion rate reached 30%, 0.1 part of t-dodecyl mercaptan was added, and 7 minutes from the start of polymerization.
After an hour, the conversion was measured to be 98%. Next, 400 parts of methyl methacrylate was added over 15 minutes,
After the polymerization was continued for 3 hours, the polymerization was stopped by water cooling 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 0.1%.
38 μm, sphericity was 1.13.

(Example 1) 80 parts of styrene, 20 parts of n-butyl acrylate, carbon black (trade name "# 2
5B ", manufactured by Mitsubishi Chemical Corporation; 7 parts by primary particle size; 1 part of a charge control agent (trade name" Spiron Black TRH "; manufactured by Hodogaya Chemical Co., Ltd.); 0.5 parts of divinylbenzene; t-dodecyl mercaptan 1. 2 parts and 10 parts of pentaerythritol tetrastearate were wet-pulverized at room temperature using a media-type wet pulverizer to obtain a polymerizable monomer composition for a core.

On the other hand, in an aqueous solution obtained by dissolving 10.2 parts of magnesium chloride (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water, 6.2 parts of sodium hydroxide (alkali metal hydroxide) in 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 particle size distribution of the produced colloid was measured with a Microtrac particle size distribution analyzer (manufactured by Nikkiso Co., Ltd.).
(50% cumulative value of number particle size distribution) is 0.35 μm, and D
90 (90% cumulative value of the number particle size distribution) was 0.84 μm. The measurement by the Microtrac particle size distribution analyzer was performed under the following conditions: measurement range = 0.12 to 704 μm, measurement time = 30 seconds, and medium = ion-exchanged water.

On the other hand, methyl methacrylate (calculated Tg =
(105 ° C.) 3 parts and 100 parts of water were finely dispersed by an ultrasonic emulsifier to obtain an aqueous dispersion of a polymerizable monomer for shell.
The particle size of the droplets of the polymerizable monomer for shell was determined by adding the obtained droplets to a 1% aqueous sodium hexametaphosphate solution at a concentration of 3% and measuring with a Microtrac particle size distribution analyzer. 0.6 μm.

The above polymerizable monomer composition was charged into the magnesium hydroxide colloidal dispersion obtained as described above, and the mixture was stirred until the droplets became stable, and t-butylperoxy-2-ethylhexanoate was added thereto. After adding 6 parts of Eat (trade name: "Perbutyl O", manufactured by NOF CORPORATION), the mixture was subjected to high shear stirring at 15,000 rpm for 30 minutes using an Ebara Milder to form droplets of the monomer mixture. Granulated. The aqueous dispersion of the granulated monomer mixture was put into a 10 L reactor equipped with a stirring blade, the polymerization reaction was started at 85 ° C., and when the polymerization conversion reached almost 100%, sampling was performed. The core particle size was measured. As a result, it was 7.2 μm.
2, as the polymerizable monomer for the shell and the water-soluble initiator,
2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide] (trade name; “VA-08
6 ", manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 65 parts of distilled water, and the solution was placed in a reactor. After continuing polymerization for 8 hours,
The reaction was stopped to obtain an aqueous dispersion of toner particles having a pH of 9.5. While stirring the aqueous dispersion of the core-shell type colored particles obtained above, the pH of the system was adjusted to 4 or less with sulfuric acid to perform acid washing (25 ° C., 10 minutes), and water was separated by filtration. The slurry was reslurried by adding 500 parts of exchanged water, and washed with water. After that, dehydration and water washing were repeated several times again, and the solid content was separated by filtration. The solid was dried at 45 ° C. for 24 hours to obtain colored particles. The volume average particle size of the colored particles is 7.2 μm, and the volume average particle size (dv) / number average particle size (dp), which is an index of the particle size distribution, is 1.2.
3. The sphericity was 1.16.

The colored particles 100 obtained by the method described above
Parts and an average particle size of 0.
38 parts of the organic fine particles obtained in the reference example having a sphericity of 1.13 and silica particles having an average particle diameter of 0.3 μm crushed by a Henschel mixer and having a sphericity of 1.12 and a hydrophobicity of 60%. A (trade name “KMPX100”, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.9 part, and the amount of siloxane compound extracted with THF hydrophobically treated with octamethylcyclotetrasiloxane as inorganic fine particles is 0.1%, average Particle size 14
nm, silica fine particles B having a hydrophobicity of 75% (trade name “R-
104 ", manufactured by Nippon Aerosil Co., Ltd.) using a Henschel mixer at a rotation speed of 1400 rpm for 10 minutes.
A toner was obtained. Printing evaluation was performed on the obtained toner. Table 1 shows the results.

[0075]

[Table 1]

(Examples 2 to 4, Comparative Examples 1 to 4) 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. In Examples 3 and 4 in Table 1, as inorganic fine particles, the amount of a siloxane compound hydrophobically treated with octamethylcyclotetrasiloxane and extracted with THF was 0.2%, and the average particle diameter was 20 n.
m, titanium oxide fine particles having a hydrophobicity of 64% (trade name “T-
805 "(manufactured by Nippon Aerosil Co., Ltd.) and Comparative Example 4, as the inorganic fine particles, silica fine particles C having an average particle diameter of 12 nm and a hydrophobicity of 65% (trade name" RX200 ", hydrophobicized with hexamethyldisilazane) as inorganic fine particles. Manufactured by Nippon Aerosil Co., Ltd.).

From the evaluation results of the toners in Table 1, the following can be understood. The toner of Comparative Example 1, in which the external additive does not contain the organic fine particles specified in the present invention, is liable to cause fogging and blurring on the photoconductor at the time of toner replenishment or after printing 20,000 sheets. The toner of Comparative Example 2 in which the external additive does not contain the silica fine particles having an average particle diameter of 0.1 to 1 μm as defined in the present invention causes fogging and blurring on the photoreceptor at the time of toner replenishment or after printing 20,000 sheets. Easy to do. The toner of Comparative Example 3 in which the external additive does not contain the inorganic fine particles specified in the present invention also has a low print density, and is liable to cause fogging and blurring on the photoconductor at the time of toner replenishment or after printing 20,000 sheets. In the toner of Comparative Example 4 using inorganic fine particles having an average particle diameter of 5 to 40 nm in which the hydrophobizing agent is hexamethyldisilazane, fogging and blurring during toner replenishment are liable to occur. In contrast, the toners of Examples 1 to 4 of the present invention
It can be seen that the print density is high, and fog and blurring on the photoreceptor hardly occur during toner replenishment or after printing 10,000 sheets.

[0078]

According to the present invention, even when recycled paper is used as a transfer material, an image having a high print density, a toner which is unlikely to cause fogging and blurring on the photoreceptor when replenishing the toner or after printing 10,000 sheets. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating one embodiment of an image forming apparatus used in an image forming method of the present invention.

[Explanation of symbols]

 1, photosensitive drum 3, charging roll 4, laser beam irradiation device 5, transfer roll 7, developing roll 8, developing roll blade 9, supply roll 10, toner 11, developing device

Claims (2)

[Claims] 1. A toner comprising at least colored particles and an external additive, wherein the external additive has an average particle size of 0.05 to 1 μm.
Characterized by comprising organic fine particles, silica fine particles having an average particle diameter of 0.03 to 1 μm, and inorganic fine particles having an average particle diameter of 5 to 40 nm which have been subjected to a hydrophobic treatment with a siloxane compound. 2. An image forming method, comprising: attaching the toner according to claim 1 to a surface of a photoreceptor on which an electrostatic latent image is recorded to form a visible image; and transferring the visible image to a transfer material. .