JP2001281918A - Toner and method for forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner with which an excellent image can be obtained even on recycled paper. SOLUTION: The toner containing substantially spheric color particles having 1 to 1.3 sphericity and silicate compound particles having 30 to 90% hydrophobicity, 0.03 to 1 μm volume average particle size and 1 to 1.3 sphericity is used to form an image in a developing device which simultaneously performs development and cleaning. The device is used for the method for development including the following processes. (1) A developing roll carrying the developer electrified into the same polarity as that of an electrostatic latent image on a photoreceptor is disposed in contact with the photoreceptor, (2) the rotation direction of the photoreceptor and the developing roll in the contact part is made identical, (3) the photoreceptor and the developing roll are rotated in such a manner that the circumferential speed of the developing roll is >=1.5 times that of the photoreceptor, and (4) while the exposed region of the photoreceptor is developed, the residual developer depositing on the unexposed region of the photoreceptor is sucked to the developing roll and removed to clean the photoreceptor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

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

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

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

[0005]

SUMMARY OF THE INVENTION The present inventor has found that when a conventional toner is applied to recycled paper, only an image having a lot of fog and blurring and a low print density can be obtained. Accordingly, as a result of intensive studies to obtain a good image even on recycled paper, it was found that this problem could be solved by using specific silicate compound particles as external additives for spherical colored particles, and the present invention was completed. I came to.

[0006]

According to the present invention, colored particles having a sphericity of 1 to 1.3, a hydrophobicity of 30 to 90%, a volume average particle diameter of 0.03 to 1 μm, A toner containing silicate compound particles having a sphericity of 1 to 1.3; and developing the toner by (1) carrying a developer charged to the same polarity as the electrostatic latent image on the photoreceptor. The roll is placed in contact with the photoconductor, (2) the rotation direction at the contact portion between the photoconductor and the developing roll is the same direction, and (3) the peripheral speed of the developing roll is 0.8 to less than the peripheral speed of the photoconductor. Rotate the photoconductor and the developing roll so that the magnification becomes 1.5 times. (4) Develop the exposed area of the photoconductor, and at the same time, remove the residual developer attached to the non-exposed area of the photoconductor by suction to the developing roll side. Cleaning that is performed simultaneously with development. Used in the apparatus, a method for forming an image is provided. In the present invention, the sphericity is a value (Sc / Sr) obtained by dividing the area (Sc) of a circle whose diameter is the absolute maximum length of the particle by the substantial projected area (Sr) of the particle, and the degree of hydrophobicity is determined by a methanol method. It is a measured value.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The toner of the present invention has a coloring particle and a hydrophobicity of 30 to 90.
%, Volume average particle size is 0.03-1 μm, sphericity is 1
It has an external additive composed of 1.3 silicate compound particles.

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

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

[0010] The particle size of the colored particles is determined by the volume average particle size (dv).
Is 3 to 12 μm, preferably 4 to 10 μm, and the ratio (dv / dn) of the volume average particle diameter to the number average particle diameter (dn) is desirably in the range of 1 to 1.4.

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

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

(Crosslinkable Compound) In the production of colored particles by the polymerization method, the use of a crosslinkable compound such as a crosslinkable monomer or a crosslinkable polymer together with the polymerizable monomer is effective for improving hot offset. The crosslinkable monomer is a monomer having two or more polymerizable carbon-carbon unsaturated double bonds. Specifically, aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof;
Diethylenically unsaturated carboxylic esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; (meth) derived from alcohols having both aliphatic terminals such as 1,4-butanediol and 1,9-nonanediol
Acrylate; divinyl compounds such as N, N-divinylaniline and divinyl ether; and compounds having three or more vinyl groups. The crosslinkable polymer is
Examples include polyethylene, polypropylene, polyester, and polysiloxane-derived (meth) acrylates having two or more hydroxyl groups in the molecule. These crosslinkable monomers and crosslinkable polymers can be used alone or in combination of two or more. The amount used is usually 10 parts by weight or less, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the polymerizable monomer. Such a polymerizable monomer or a crosslinkable compound is polymerized to form a binder resin.

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

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

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

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

As the magenta colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I.
I. Pigment Red 48, 57, 58, 60, 63,
64, 68, 81, 83, 87, 88, 89, 90, 1
12, 114, 122, 123, 144, 146, 14
9, 163, 170, 184, 185, 187, 20
2, 206, 207, 209, 251, C.I. I. Pigment Violet 19 and the like.

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

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

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

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

The charge control agent is preferably contained in the colored particles in order to improve the chargeability of the toner. Various charge control agents can be used as the charge control agent. As the charge control agent, for example, Bontron N01
(Orient Chemical Co., Ltd.), Nigrosine Base EX (Orient Chemical Co., Ltd.), Spiro Black TRH (Hodogaya Chemical Co., Ltd.), T-77 (Hodogaya Chemical Co., Ltd.), Bontron S-34 (Orient Chemical Co., Ltd.), Bontron E -81
(Orient Chemical Co.), Bontron E-84 (Orient Chemical Co.), Bontron E-89 (Orient Chemical Co.), Bontron F-21 (Orient Chemical Co.),
COPY CHRGE NX (manufactured by Clariant), C
OPY CHRGE NEG (Clariant),
TNS-4-1 (manufactured by Hodogaya Chemical Co., Ltd.), TNS-4-2
Charge control agents such as (Hodogaya Chemical Co., Ltd.) and LR-147 (Nippon Carlit Co., Ltd.), JP-A-11-15192, JP-A-3-175456, JP-A-3-243.
No. 954, etc., quaternary ammonium (salt) group-containing copolymers, JP-A-3-243954, JP-A-1
A charge control agent (charge control resin) such as a sulfonic acid (salt) group-containing copolymer described in JP-A-217264 and JP-A-3-15858 can be used. Among these, the charge control resin has high compatibility with the binder resin,
It is colorless and is preferable in that a toner having stable chargeability can be obtained even in high-speed color continuous printing. The proportion of the charge control resin in the resin such as a structural unit having a positive or negative chargeability, for example, a structural unit having an ammonium group or a sulfonate group, is preferably 1 to 10% by weight. It is relatively difficult to obtain sufficient chargeability when the proportion of the structural unit having such a charge-providing group is small, and conversely, when the proportion of the structural unit is too large, the charge amount becomes too high and good. There is a tendency that image quality cannot be obtained. The charge control agent is generally used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 100 parts by weight, based on 100 parts by weight of the binder resin or the polymerizable monomer.
It is used in a proportion of up to 7 parts by weight.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

(External Additive) Silicate compound particles as an external additive are added to the above-mentioned colored particles and mixed to obtain a toner. The silicate compound particles used in the present invention have a hydrophobicity of 3
0 to 90%, preferably 50 to 90%, and the number average particle size is 0.03 to 1 μm, preferably 0.05 to 0.8.
μm and a sphericity of 1 to 1.3, preferably 1 to 1.
2. If the degree of hydrophobicity is too low, fogging may occur when printing under high temperature and high humidity. If the degree of hydrophobicity is too high, fog may occur when printing under low temperature and low humidity. If the number average particle size is too small, filming may not be prevented, while if too large, the fluidity may be reduced. If the sphericity is too large, the transferability may be reduced, and blurring may occur. Since such a silicate compound is spherical, there is an advantage that the photoreceptor is hardly damaged.

As the silicate compound particles, high purity ultrafine silica particles containing 99% or more of silica are particularly preferable. Silica may be obtained by any method such as a gas phase decomposition method, a combustion method, and a deflagration method. For example, silica obtained by cooling a vapor-like silicon oxide produced by burning metallic silicon powder has a high sphericity and is desirable (Japanese Patent Application Laid-Open Nos. 60-255602 and 2-28).
9404, JP-A-3-170319). In this production method, the particle size of the silica obtained by controlling the combustion and cooling conditions can be changed as appropriate, and usually the average primary particle size (hereinafter sometimes simply referred to as the particle size) is from 1 nm to 10 nm. It is possible to obtain spherical fine particles of any size having a uniform size between 2,000 nm. Silica prepared by such a method has a substantially spherical shape and does not have pores, so that the content of SiOH groups affecting the charging characteristics of the toner is higher than that of silica prepared by a normal gas phase method. Therefore, there is an advantage that the amount used as an external additive can be reduced. Even if a surface treating agent is not used, or even if it is used, the amount of the external additive used can be reduced, which is economically advantageous. Also, because of the large particle size,
It is possible to contribute to prevention of deterioration in chargeability and transferability without being buried during toner durable printing. Further, by using together with silica having a relatively small average particle diameter of 5 nm or more, a decrease in fluidity can be relatively suppressed.

In the present invention, organic or inorganic fine particles generally used as an external additive of a toner can be used in addition to the spherical silica. Organic fine particles include methacrylate polymer particles, acrylate polymer particles, styrene-methacrylate copolymer particles, styrene-acrylate copolymer particles, zinc stearate, calcium stearate, and a core of methacrylic acid. Core-shell type particles in which a shell is formed of a styrene polymer in an ester copolymer are exemplified. As the inorganic fine particles, silicate compounds other than the above-mentioned spherical silica,
Aluminum oxide, zinc oxide, tin oxide, barium titanate, strontium titanate, or the like can also be used. It is desirable that such fine particles other than spherical silica be used together in a range of 50% by weight or less, preferably 45% by weight or less based on the total amount of the external additives.

In particular, the toner of the present invention comprises: (1) a developing roll carrying a developer charged to the same polarity as the electrostatic latent image on the photoreceptor is disposed in contact with the photoreceptor; The rotation direction at the contact portion with the developing roll is the same direction,
(3) The peripheral speed of the developing roll is 0.8 to 1.
The photosensitive member and the developing roll are rotated so that the ratio becomes 5 times, preferably 0.8 to 1.3 times. (4) The exposed region of the photosensitive member is developed and, at the same time, the residual material adhered to the non-exposed region of the photosensitive member. It is suitable for a developing device (hereinafter, referred to as a cleaner-less device) that performs cleaning at the same time as developing, which is employed in a developing method of cleaning by suctioning and removing a developer toward a developing roll. When only a general external additive is used, the repetition of printing lowers the fluidity, causes toner filming on the surface of the photoreceptor and the developing blade, and adversely affects printing (fogging). This tendency is particularly remarkable when recycled paper is used.

As a specific example of the cleanerless device, there is a device having a schematic sectional view as shown in FIG. When developing and cleaning using this device,
The residual toner on the photoconductor 1 after the transfer process is collected in the developing device 5 according to the following principle. That is, the photoconductor 1
The surface potential of the unexposed area (non-latent image area) is Vo, the exposed area of the exposed area (latent image area) is Vq, the developing bias voltage applied to the developing roll 8 is Vb, and the surface of the developing roll 8 is The potential Ve is equal to the developing bias voltage Vb. The electrostatic latent image on the photoconductor 1 is reversely developed with toner charged to the same polarity as the electrostatic latent image.

In particular, when the colored particles are obtained by a polymerization method, the transfer efficiency to transfer paper becomes as high as 90% or more, and in order to satisfy both the image density and the cleaning property, each surface potential Vo, Ve And Vq, the thickness of the toner layer formed on the developing roll, and the setting range of appropriate conditions for the rotation ratio between the photoconductor and the developing roll are preferably widened.

[0048]

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 The volume average particle size (dv) of the colored particles (toner particles) and the particle size distribution, that is, the ratio (dv / dp) of the volume average particle size to the number average particle size (dp). ) Is a value measured by a multisizer (manufactured by Beckman Coulter). The measurement by this multisizer was as follows: aperture diameter: 100 μm, medium:
Isoton II, concentration 10%, number of measured particles: 10000
Performed under zero conditions. -Number average particle diameter The particle diameter of the external additive is determined by taking an electron micrograph of each particle and using the photograph as an image processing / analyzing device Luzex IID [Co., Ltd.]
This is an average value measured and analyzed under the conditions that the area ratio of particles to the frame area is 2% at the maximum and the total number of particles processed is 100.・ Sphericality The sphericity (Sc / Sr) is obtained by taking an electron micrograph of each particle and using the photograph as an image processing / analyzing device Luzex IID.
This is an average value measured and analyzed under the conditions that the area ratio of particles to the frame area is 2% at the maximum and the total number of particles processed is 100, according to [manufactured by Nireco Corporation]. -Degree of hydrophobicity 0.2 g of inorganic fine powder is weighed into a 200 ml beaker,
50 ml of pure water was added, and methanol was gradually added below the liquid level while stirring with a magnetic stirrer.
The point at which no powder is recognized on the liquid surface is defined as the end point, and is a value calculated by the following equation. Degree of hydrophobicity (%) = X / (50 + X) × 100 X; Methanol usage (ml)

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

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

(Reference Example) Synthesis of quaternary ammonium base-containing copolymer (positive charge control resin) 85% styrene, 9% n-butyl acrylate, and N
-Benzyl-N, N-dimethyl-N- (2-methacryloxyethyl) ammonium chloride (100 parts) is charged into a mixed solvent of toluene (500 parts) and methanol (400 parts). The reaction was carried out at 80 ° C. for 8 hours in the presence of 4 parts of dimethylvaleronitrile. After the reaction, the solvent was distilled off to obtain a quaternary ammonium base-containing copolymer (hereinafter, referred to as charge control resin A).
The obtained charge control resin A had a weight average molecular weight of 2.3 × 1.
0 ⁴ was ammonium salt of 6 wt%.

2. Synthesis of sulfonic acid group-containing copolymer (negative charge control resin) 86% styrene, 9% n-butyl acrylate, and 2
-Acrylamide-2-methylpropanesulfonic acid 5%
Was added to 900 parts of toluene, and reacted at 80 ° C. for 8 hours in the presence of 4 parts of azobisdimethylvaleronitrile. After the reaction, the solvent was distilled off, and the sulfonic acid group-containing copolymer (hereinafter referred to as charge control resin B) was removed.
). The obtained charge control resin B had a weight average molecular weight of 1.6 × 10 ⁴ and a sulfonic acid group content of 5% by weight.

(Examples 1-2, Comparative Examples 1-6) 80 parts of styrene, 20 parts of n-butyl acrylate, carbon black (trade name "# 25B", manufactured by Mitsubishi Chemical Corporation; primary particle size: 4)
0 nm) 6 parts, the charge control resin described in Table 1 0.5 part, divinylbenzene 0.6 part, t-dodecyl mercaptan 1
Part and sasol wax (trade name "Paraflint"
Spray 30 "(manufactured by Sasol Co.) was dispersed in a bead mill at room temperature to obtain a uniform mixed solution. While stirring the mixture, 5 parts of a polymerization initiator “Perbutyl O” (trade name, manufactured by NOF Corporation) was added, and stirring was continued until the droplets became uniform to form a polymerizable monomer composition. Obtained.

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

While stirring the aqueous dispersion of the polymer particles obtained as described above, the pH of the system was adjusted to 4 or less with sulfuric acid, acid washing was performed, water was separated by filtration, and 500 parts of ion-exchanged water was newly added. In addition, the slurry was reslurried and washed with water. After that, dehydration and washing with water were repeated several times again, and the solid content was separated by filtration, followed by drying at 45 ° C. for 2 days and night with a drier to obtain colored particles.

The colored particles 10 obtained by the method described above
0 parts, external additives A to E, and inorganic fine particles (silica particles, trade name: RX-200, manufactured by Nippon Aerosil Co., Ltd.)
12 nm) and organic fine particles (particle diameter 0.4 μm, sphericity:
And a capsule structure having styrene as a shell with polymethyl methacrylate particles of 1.16 as a core), and mixing with a Henschel mixer for 10 minutes at 1400 rpm to obtain a toner. Printing evaluation was performed on the obtained toner. Table 1 shows the results.

[0058]

[Table 1]

The silicate compound particles used as the external additive are as follows. Spherical silica A: hydrophobicity 82%, volume average particle size 0.5μ
m, spherical silica having a sphericity of 1.2 spherical silica B: hydrophobicity: 24%, volume average particle diameter: 0.5 μm
m, spherical silica having a sphericity of 1.3 spherical silica C: hydrophobicity: 72%, volume average particle size: 0.01
μm, spherical silica having a sphericity of 1.2 spherical silica D: hydrophobicity: 77%, volume average particle diameter: 2 μm,
Spherical silica having a sphericity of 1.1 Spherical silica E: hydrophobicity 89%, volume average particle diameter 0.4 μm
m, spherical silica with a sphericity of 1.5

From the above results, in the example using the specific external additive, there was no fog on the photoreceptor, good printing was obtained, and the comparative example using the external additive outside the scope of the present invention was obtained. Then, after printing 7500 sheets, there is fog on the photoconductor,
It was found that the print was blurred and stained. Even if the print looks good, if there is fog on the photoconductor,
In a poor environment such as high temperature and high humidity, there is an adverse effect on printing, and such a toner cannot be said to be a good quality toner.

[0061]

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

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a cleanerless device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor 3 charging roll 4 exposure device 5 developing device 6 transfer roll 7 transfer paper 8 developing roll 9 developing roll blade 10 developer 11 casing 12 developer supply roll

Claims (2)

[Claims] 1. Colored particles having a sphericity of 1 to 1.3,
Hydrophobicity 30-90%, number average particle size 0.03-1
and a silicate compound particle having a sphericity of 1 to 1.3 μm. And (2) a developing roller carrying toner charged to the same polarity as the electrostatic latent image on the photoconductor is disposed in contact with the photoconductor, and (2) a contact portion between the photoconductor and the developing roller. (3) rotating the photoconductor and the developing roll so that the peripheral speed of the developing roller is 0.8 to 1.5 times the peripheral speed of the photoconductor; An image forming method using the toner according to claim 1 in a developing method for developing by removing an exposed area and removing a residual developer attached to a non-exposed area of a photoconductor by suction to a developing roll side for cleaning.