JP2548091B2 - Development method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method for developing an electrostatic charge image, and particularly to a number average particle size and DBP method (AST
M-D2414-65T) and the amount of oil absorption according to
Suspension polymerization is carried out from a monomer composition comprising a polymerizable monomer and a low softening point compound having a softening point of 40 to 130 ° C. (may be referred to as “low softening point wax” in the present specification). And a developing method using a non-magnetic black polymerized toner.

[0002]

2. Description of the Related Art When a developing toner is obtained by a conventional general suspension polymerization method, a monomer composition containing at least a colorant and a polymerizable monomer is used as a toner in an aqueous medium. Polymerized by polymerizing the polymerizable monomer by radicals generated when the polymerization initiator (or newly added polymerization initiator) added in advance is decomposed by heat. To form a polymerized toner. That is, since the pulverization step is not included in this method, the polymerized toner does not need to have brittleness, and since the shape thereof is spherical, the polymerized toner has excellent fluidity,
It has features such as uniform triboelectrification.

In recent years, improvements in image quality of copied images, speeding up of copying machines and / or energy saving have been aimed at, so that the developing characteristics of toner are further improved and blocking resistance, fluidity and abrasion resistance are not lowered. In addition, a toner capable of forming a good fixed image by lower temperature fixing and / or low pressure fixing is desired.

In order to obtain such a toner, production of a polymerized toner in which a monomer composition contains a solid paraffin wax having a shape-retaining property at room temperature or a low softening point compound such as a low molecular weight polyolefin. Is being attempted.

[0005]

However, it is not always easy to granulate carbon black into a suitable particle size while uniformly dispersing carbon black in a polymerizable monomer, and a low softening point compound ( In general, coexistence of (having a lower affinity for carbon black than that of the polymerizable monomer) tends to make it more difficult to uniformly perform the above dispersion and granulation. As a result, if a low-softening point compound is simply allowed to coexist in a system composed of a polymerizable monomer and carbon black (for example, in an aqueous medium) and granulated, the dispersion of carbon black is not uniform. Problems such as not being formed and carbon black being liberated from the toner binder have arisen, and when trying to improve the fixing properties of the toner, it was difficult to avoid deterioration of image quality such as image density and resolution.

A main object of the present invention is a developing method using a toner having improved image characteristics, that is, a non-magnetic black polymerized toner having good dispersibility of carbon black and giving proper image density and high resolution. To provide.

[0007]

Means and Actions for Solving the Problems As a result of intensive studies conducted by the present inventors for the above-mentioned purpose, the present inventors have found that a mixed system composed of carbon black and a polymerizable monomer is allowed to coexist with a low softening point wax. When granulating, it was found that the dispersion as a whole monomer composition containing all of these components and the dynamic characteristics (particularly the viscosity) during granulation are extremely important. In order to realize it, it was found that it is important to use carbon black having specific physical properties and to include a low softening point wax having a certain softening point.

The developing method of the present invention comprises: (A) (i) a polymerizable monomer containing at least a styrene monomer; and (ii)
Carbon black having a number average particle diameter of 40 to 300 mμ and an oil absorption of 100 (cc / 100 g) or less by the DBP method, (iii) a polar polymer, a polar copolymer or a cyclized rubber, and (iv) softening Non-magnetic black polymerized toner particles produced by a suspension polymerization method from a monomer composition containing a low softening point wax having a point of 40 to 130 ° C., and
(B) A magnetic brush is formed on a developer carrier with a two-component developer having insulating magnetic carrier particles, and an electrostatic charge image formed on the image carrier while applying an AC bias to the developer carrier. It is characterized by developing with non-magnetic black polymerized toner particles.

The reason why such an effect is obtained in the non-magnetic black polymerized toner used in the developing method of the present invention is not clear, but it is presumed as follows.

That is, when a toner is produced by a conventional suspension polymerization method, a mixed system comprising a polymerizable monomer and carbon black usually has a certain degree of viscosity, but in addition to this, a large amount of low The coexistence of the softening point compound significantly increases the viscosity of the monomer composition. Therefore, it becomes difficult to uniformly disperse the carbon black in such a monomer composition, and even if the carbon black can be uniformly dispersed, it is not possible to granulate to a particle size suitable as a toner. It will be extremely difficult.

Therefore, when a low-softening point compound is simply allowed to coexist using the conventional manufacturing method, carbon black particles not bound with a resin or resin particles containing no carbon black are generated, and the blackness of the entire toner is lowered. It is presumed that a toner having uniform fixing characteristics and image characteristics and good toner cannot be obtained due to non-uniform electric characteristics and variations in particle size and specific gravity.

On the other hand, when the toner used in the present invention is manufactured, carbon black having an average particle diameter and an oil absorption amount by the DBP method within a specific range is mixed with a polymerizable monomer.
Even when dispersed in a mixed system with a low softening point compound, the viscosity of the monomer composition consisting of these components is suppressed within a certain range, so that in this monomer composition, uniform dispersion of carbon black It is presumed that the property and suitable granulation property can be obtained.

Therefore, according to the present invention, not only good low temperature fixing property and / or low pressure fixing property of the toner based on the inclusion of the low softening point compound can be obtained, but also the carbon black is uniformly and satisfactorily with respect to the binder resin. It is presumed that a dispersed toner is obtained, and the above-mentioned drawbacks of the conventional polymerization toner are eliminated.

According to the present invention, the encapsulation of such a low softening point compound and the high dispersibility of carbon black are characteristics of a suspension polymerization toner (for example, deterioration of a binder resin is prevented, and almost all of them are prevented). In addition to the above-mentioned characteristics, by being combined with spherical toner particles),
High fluidity, good chargeability due to friction with insulating magnetic carrier particles, etc., good separation from developer layer during development, selective adsorption to electrostatic image, etc. A toner having various excellent image characteristics that a developed toner image is easily transferred to a recording medium such as paper, and further excellent in storability and durability can be obtained.

The present invention will be described in more detail below. In the following description, “%” and “part” representing the quantitative ratio are based on weight unless otherwise specified.

The non-magnetic black polymerized toner used in the present invention comprises (i) a polymerizable monomer containing styrene and (i)
A single compound containing i) carbon black having a specific particle size and oil absorption, (iii) a polar polymer, a polar copolymer or a cyclized rubber, and (iv) a low softening point compound having a softening point of 40 to 130 ° C. The polymer composition is suspension-polymerized.

The non-magnetic black polymerized toner used in the present invention usually has a volume average particle diameter of about 0.1 to about 30 μm.

The polymerized toner is excellent in blocking resistance as compared with the conventional polymerized toner even if it contains a large amount of the low softening point compound. This is because the low softening point compound is well encapsulated in the polymer obtained by polymerizing the polymerizable monomer, and the low softening point compound is not exposed on the surface of the polymerized toner particles.

Whether or not the low softening point compound is substantially encapsulated in the polymer is confirmed as follows. That is, the obtained polymerized toner is melt-kneaded, cooled and solidified, then pulverized, and then classified to prepare a pulverized powder having an average particle size similar to that of the polymerized toner, and the prepared pulverized powder has an anti-blocking property. By comparing the property and the blocking resistance of the polymerized toner used as the raw material, the presence or absence of the inclusion is confirmed.

This blocking resistance is obtained by, for example, putting 1 to 5 g of a sample in a 100 ml container having a diameter of about 5 cm and applying a temperature of 5
It can be measured by the presence or absence of aggregates with a long particle size of about 1 mm or more remaining on a 20-mesh sieve (Taylor mesh) after being left for one day in an environment of 0 ° C. and a relative humidity of about 60 ± 5%.

In the present invention, the carbon black has a number average particle size of 40 to 300 mμ (preferably 50).
~ 200 mμ) and DBP method (ASTM D2414)
An oil absorption of −65T) of 100 (cc / 100 g) or less, preferably 70 (cc / 100 g) or less is used.

The number average particle size of the carbon black is 4
If it is less than 0 mμ, the surface area of carbon black is large,
Since aggregation easily occurs, good dispersibility of carbon black in the low softening point compound cannot be obtained.

On the other hand, although carbon black having a particle size of more than 300 mμ has good dispersibility, it is not suitable as a toner for electrostatic charge development because the blackness of carbon black itself is low.

The particle size is large to some extent as described above (4
(0 to 300 mμ) By using carbon black, it becomes possible to disperse carbon black even in a mixture of a polymerizable monomer and a low softening point compound,
Even in the toner obtained by suspension polymerization, good dispersibility of carbon black can be obtained.

On the other hand, when the oil absorption of carbon black by the DBP method exceeds 100 (cc / 100 g), the viscosity of the monomer composition mixed with the polymerizable monomer containing the low softening point compound (carbon black Since it rises (more than when not mixed), it becomes difficult to carry out suspension granulation of the monomer composition in an aqueous medium or the like to a particle size of a toner level. Therefore, due to the relationship between the dispersibility of carbon black and the viscosity of the monomer composition, the carbon black to be used in the suspension-polymerized toner preferably used in the present invention is limited by its number average particle size and oil absorption. To be done.

In the present invention, by using the carbon black limited by such a number average particle diameter and the oil absorption amount, the dispersion of the carbon black in the monomer composition becomes uniform and the carbon black is Less resin particles not included. Therefore, particularly in the present invention,
Even in the case of a toner having a number average particle diameter of 5 μm or less, which has conventionally generated a large amount of resin containing no carbon black, it is possible to extremely reduce the generation of resin particles containing no carbon black.

The carbon black that can be used in the present invention is
Examples of commercially available products include the following, but the products are not limited to the following as long as they have the above number average particle diameter and oil absorption.

For example, legal (R
EGAL) SRF-S, STERING
SO, Stelling V, Stelling R, Stelling NS,
CSX-238; Columbia Carbon Japan Co., Ltd. RAVEN H20, RAVEN MT-P, RAVEN 410, RAVEN 420, RAVEN 430, RAVEN 450, RAVEN 500; Printex 25, Special made by Degussa of West Germany. Black (S
specific Black) 100, Printex G; manufactured by Mitsubishi Kasei Co., Ltd., CF9, # 10B, # 5
B; etc. are mentioned.

These carbon blacks may be used alone or in combination of two or more in various compositions.

The amount of carbon black contained in the toner is usually 3 with respect to 100 parts of the toner binder resin composed of the polymer of the polymerizable monomer and the low softening point compound.
-30 parts (more preferably 5-20 parts) are preferred.

In the non-magnetic black polymerized toner used in the present invention, carbon black, which is a colorant, is present during or before the polymerization of the binder polymer. Therefore, a pigment is added to the polymer later. It is presumed that it is not necessary to melt and knead the polymer, and therefore there is no alteration due to the breakage of the molecular chain during the kneading of the polymer, and a toner having excellent properties can be obtained.

Further, since the toner used in the present invention is a spherical toner which has not undergone the pulverizing step, it has better fluidity than the irregular toner which has undergone the pulverizing step, and the carbon black is dispersed uniformly as described above. Therefore, the triboelectric chargeability of the toner is uniform and stable.

When the toner used in the present invention is manufactured, the viscosity of a monomer composition containing at least a polymerizable monomer, a low softening point compound having a softening point of 40 to 130 ° C. and carbon black is excessively high. Since it does not occur, dispersion in the dispersion medium,
By suspending, the monomer composition can be easily suspended to a particle size equal to or smaller than the conventional toner particle size, and the particle size distribution can be narrowed.

Even when the number average particle diameter of the polymerized toner used in the present invention is 5 μm or less, the electrophotographic image using such toner has excellent resolving power,
Further, since the dispersibility of carbon black in the toner is also good, a sufficient image density can be obtained and a high quality image can be obtained.
When the number average particle diameter of the toner is larger than 5 μm, there is a tendency that the resolving power is deteriorated due to popping and the like.

As the polymerizable monomer constituting the binder resin of the non-magnetic black polymerized toner used in the present invention, a polymerizable monomer can be used without particular limitation.

Examples of such a polymerizable monomer include styrene, o-methylstyrene, m-methylstyrene,
p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert. Styrene and derivatives thereof such as -butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene; ethylene, propylene, Ethylene unsaturated monoolefins such as butylene and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; methacrylic acid Methyl, ethyl methacrylate, propyl methacrylate, metac Α-Methylene such as n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate. Aliphatic monocarboxylic acid esters; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate,
Acrylic acid esters such as 2-chloroethyl acrylate and phenyl acrylate; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N -Vinylpyrrole, N-vinylcarbazole,
N such as N-vinylindole and N-vinylpyrrolidone
-Vinyl compounds; vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

These monomers may be used alone or in combination of two or more in various compositions as required.

On the other hand, the low softening point compound means a softening point of 40 to 130 ° C., preferably 50 to 120 ° C. measured by a ring and ball method.
Is to have. If the softening point is less than 40 ° C, the blocking resistance of the toner is insufficient, and if it exceeds 130 ° C, the effect of lowering the fixing temperature of the toner is small.

Examples of the low softening point compound include paraffin, low molecular weight polyolefin, modified wax having an aromatic group, hydrocarbon compound having an alicyclic group, natural wax, and long chain having a long hydrocarbon chain having 12 or more carbon atoms. Examples thereof include carboxylic acid and its ester.

Specifically, as the low-softening point compound, paraffin wax (manufactured by Nippon Oil Co., Ltd.), paraffin wax (manufactured by Nippon Seiro Co., Ltd.), microwax (manufactured by Nippon Oil Co., Ltd.), microcrystalline wax (manufactured by Nippon Seiro Wax Co., Ltd.) PE- Thirteen
0 (manufactured by Hoechst); Mitsui High Wax 110P, Mitsui High Wax Chair 220P, Mitsui High Wax 660P, Mitsui High Wax 210P, Mitsui High Wax 320P,
Mitsui High Wax 410P, Mitsui High Wax 420
P, Highlets T-100X, Highlets T-200
X, Highlets T-300X (Mitsui Petrochemical Co., Ltd.);
Petrosin 80, Petrosin 100, Petrosin 12
0, Tack Ace A-100, Tack Ace F-10
0, Tuck Ace B-60, modified wax JC-141
1, modified wax JC-2130, modified wax JC-
4020, modified wax JC-1142, modified wax JC-5020 (all manufactured by Mitsui Petrochemical Co., Ltd.); beeswax, carnauba wax, montan wax and the like. The addition amount of these low softening point compounds is preferably 50 to 3000 parts, and more preferably 50 to 1000 parts, relative to 100 parts of the polymerizable monomer.

A toner obtained by suspension polymerization of a monomer composition containing the above-mentioned polymerizable monomer, carbon black, a polar polymer, a low softening point compound, etc.
The number of white toner particles (toner particles containing no carbon black or toner particles containing a small amount of carbon black) W and black toner particles (containing carbon black When the number B of the toner particles having high blackness) is measured,

[0042]

[Equation 1] Value (hereinafter referred to as "carbon black dispersion rate") is 8
It is preferably 0% by number or more, and more preferably 85% by number or more.

In obtaining the toner used in the present invention,
As a polymerization initiator used for polymerizing the above-mentioned monomer composition, an initiator used in a usual polymerization reaction can be used without particular limitation.

The polymerization initiator is soluble in the polymerizable monomer, and can be satisfactorily converted into the polymerizable monomer in the amount range usually used (2 to 5 parts of the polymerization initiator to 100 parts of the monomer). It preferably has the property of dissolving.

As the polymerization initiator usable in the present invention,
2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,
Azo-based or diazo-based such as 1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and other azobisisobutyronitrile (AIBN) Polymerization initiators: Examples include peroxide type polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide and lauroyl peroxide. You may mix and use 2 or more types of these polymerization initiators.

It is generally sufficient to use about 0.1 to 10% (more preferably 0.5 to 5%) of the total weight of the monomers in the monomer composition.

Further, the following crosslinking agent may be present in the monomer composition and polymerized to obtain a toner containing a crosslinked polymer.

Examples of such a cross-linking agent include divinylbenzene, divinylnaphthalene, divinyl ether, divinyl sulfone, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate,
Ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate,
1,3-butylene glycol dimethacrylate, 1,6
-Hexane glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) propane, 2,2'-bis (4-acryl) Roxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, dibromoneopentyl glycol dimethacrylate, diallyl phthalate and the like can be appropriately used.

If the amount of these cross-linking agents used is too large, the polymer is unlikely to dissolve or melt, resulting in poor fixability. If the amount of the cross-linking agent used is too small, the properties such as blocking resistance and durability required for the toner deteriorate, and during heat roll fixing, part of the toner does not adhere completely to the paper and adheres to the roller surface. , It becomes difficult to prevent the offset phenomenon of transferring to the next paper.

Therefore, these crosslinking agents are preferably contained in 0.001 to 15 parts (more preferably 0.1 to 10 parts) per 100 parts of the monomer composition.

A charge control agent, various colorants, and a fluidity modifier may be added to the toner used in the present invention, if necessary. The charge control agent and the fluidity modifier may be used as a mixture (external addition) with toner particles. Examples of the charge control agent include metal-containing dyes and nigrosine, and examples of the fluidity modifier include colloidal silica and fatty acid metal salts. Further, for the purpose of increasing the amount, a filler such as calcium carbonate or fine powder silica may be blended in the toner in an amount of 0.5 to 20% by weight. Further, in order to prevent the mutual aggregation of the toner particles and improve the fluidity, a fluidity improver such as Teflon fine powder may be added.

When a hydrocarbon compound or carnauba wax, which improves releasability at the time of heat roll fixing, is used as a low softening point compound, for example, since the hydrocarbon compound is hydrophobic and has a low molecular weight, polymerization is performed. It is less likely to mix with the polymer produced by, and is less likely to be exposed on the surface than the polar polymer, and will be pushed into the polymerized toner. As a result, even if a large amount of the low softening point compound is contained, since it is encapsulated, the toner has excellent durability and blocking resistance. Then, at the time of fixing, the low-softening point compound comes out of the inside of the toner and remarkably improves the fixing property and the offset property. At this time, the hydrocarbon compound is considered to act as a plasticizer, a lubricant, and an oil-like function.

When the monomer is polymerized, a polar polymer having a polar group, a polar copolymer, or a cyclized rubber is added as an additive to polymerize the monomer to obtain a preferable polymerized toner. . In this case, a polar polymer having a polar group, a polar copolymer, or a monomer composition containing a cyclized rubber is suspended in an aqueous phase in which a dispersant having an opposite charge to the polar polymer is dispersed. It is preferable to polymerize.

That is, the cationic or anionic polymer, copolymer or cyclized rubber contained in the monomer composition is
The oppositely charged anionic or cationic dispersant dispersed in the aqueous medium is electrostatically attracted to the toner particle surface, and the dispersant covers the particle surface, preventing coalescence of particles and stabilization. At the same time, since the added polar polymer or the like gathers on the surface layer of the particles to be the toner, a kind of shell-like morphology is formed, and the obtained particles become pseudo capsules.

When a relatively high molecular weight polar polymer, copolymer or cyclized rubber is used, the polymerized toner particles are provided with excellent blocking resistance, developability and abrasion resistance. The polar polymer (including the polar copolymer) and the reverse charge dispersant which can be used in the present invention are exemplified below.
The polar polymer preferably has a weight average molecular weight of 5,000 to 500,000 as measured by GPC (gel permeation chromatography).

(1) Examples of the cationic polymer include polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl acrylate, or copolymers of styrene, unsaturated carboxylic acid ester and the like with the nitrogen-containing monomers. There is a polymer.

(2) Examples of the anionic polymer include nitrile monomers such as acrylonitrile, halogen-containing monomers such as vinyl chloride, unsaturated carboxylic acids such as acrylic acid, unsaturated dibasic acids and unsaturated monomers. There are dibasic anhydride polymers.

(3) Colloidal silica such as Aerosil # 200, # 300 (manufactured by Nippon Aerosil Co., Ltd.) is used as the anionic dispersant.

(4) Examples of the cationic dispersant include aluminum oxide, magnesium hydroxide, fine hydrophilic hydrophilic silica powder such as aminoalkyl-modified colloidal silica, and the like.

A cyclized rubber having an anionic property may be used instead of the polar polymer.

In addition, in the monomer composition, chain transfer agents such as lauryl mercaptan, various plasticizers, charge control agents, magnetic particles, modifying polymers, prepolymers, oligomers, conductive particles, Organic / inorganic pigments and dyes may be included.

In producing the toner used in the present invention,
The suspension polymerization reaction is usually carried out at a polymerization temperature of 50 ° C. or higher,
The upper limit temperature is set in consideration of the decomposition rate of the polymerization initiator. If the set polymerization temperature is too high, the polymerization initiator will be rapidly decomposed, which is not preferable.

Therefore, when the softening point temperature of the low-softening point compound used is high (usually 70 ° C. or higher), granulation at a temperature suitable for polymerization cannot be performed because the viscosity of the monomer composition increases. Therefore, the temperature of the dispersion medium (for example, an aqueous dispersion medium) is kept above the softening point, and after granulating the monomer composition without adding the polymerization initiator first, the temperature of the dispersion system is set to the polymerization temperature. A special method of adding a polymerization initiator to a polymerization system (for example, in an aqueous medium) after lowering to a temperature range below a suitable upper limit temperature is required.

The suspension and granulation of the monomer composition in the dispersion medium are preferably carried out, for example, as follows. That is, a polymerizable monomer (such as an additive as necessary) is uniformly dissolved or dispersed in a dispersion of a colorant (carbon black) and a low softening point compound to obtain a monomer composition, This monomer composition is dispersed in a dispersion medium (eg, polymerization temperature) substantially incompatible with the above monomer containing 0.1 to 50% by weight of a suspension stabilizer (eg, a sparingly soluble inorganic dispersant). In an aqueous medium heated to a temperature of 5 ° C. or higher, preferably 10 ° C. or higher, by a usual stirrer, homomixer, homogenizer or the like. Preferably, the stirring speed, time and liquid temperature of the aqueous medium are adjusted so that the monomer droplets have a desired toner particle size, generally 30 μm or less (for example, a volume average particle size of 0.1 to 20 μm). . After that, the liquid temperature of the dispersion medium is lowered to the polymerization temperature while stirring is performed to such an extent that the sedimentation of the particles is prevented so that the state is almost maintained by the action of the dispersion stabilizer.

The polymerization temperature is 50 ° C. or higher, preferably 55 to
Set to a temperature of 80 ° C, particularly preferably 60-75 ° C,
The polymerization is carried out by adding a substantially water-insoluble polymerization initiator to the polymerization system (for example, in an aqueous medium) while stirring. After the completion of the reaction, the produced toner particles are collected by an appropriate method such as washing, filtration, decantation, centrifugation and the like, and dried to obtain a polymerized toner. In the suspension polymerization method, water 200 to 3 is usually added to 100 parts of the polymerizable monomer.
It is preferred to use 000 parts as the aqueous dispersion medium.

Suitable stabilizers such as polyvinyl alcohol, gelatin, methyl cellulose, methyl hydropropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and salts thereof, starch, gum alginate, zein, casein, Tricalcium phosphate, talc, clay, silicic acid, barium sulfate, calcium sulfate, barium carbonate, magnesium carbonate, bentonite, aluminum hydroxide,
Ferric hydroxide, titanium hydroxide, thorium hydroxide, metal oxides, etc. may be contained alone or in admixture in an aqueous medium to such an extent that they do not adversely affect the production method of the toner of the present invention. You may also use the one.

Further, in order to disperse the inorganic dispersant uniformly, it is also possible to use a surfactant to such an extent that it does not adversely affect. This is for promoting the intended action of the above dispersion stabilizer, and specific examples thereof include sodium dodecylbenzenesulfonate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, and allyl-alkyl-poly. Sodium ether sulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, 3,3-disulfone diphenylurea-
4,4-diazo-bis-amino-8-naphthol-6-
Sodium sulfonate, ortho-carboxybenzene-
Azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-
Naphthol-sodium disulfonate and the like can be mentioned.

Further, since a water-soluble monomer causes emulsion polymerization in water at the same time and pollutes the resulting suspension polymer with small emulsion-polymerized particles, a water-soluble polymerization inhibitor such as a metal salt may be added. It is also possible to prevent emulsion polymerization in the aqueous phase. It is also possible to add glycerin, glycol, etc. to water in order to increase the viscosity of the aqueous medium and prevent coalescence of particles during polymerization. It is also possible to add salts such as NaCl, KCl and Na ₂ SO ₄ in order to reduce the solubility of the easily soluble monomer in water, or to add Bronsted acid such as hydrochloric acid to the aqueous medium in order to increase the ionicity of the polar group. It is possible.

In the present invention, as will be apparent from Examples and Comparative Examples described later, a two-component developer having non-magnetic black polymerized toner particles and insulating magnetic carrier particles is used, and an AC bias is applied to the developer carrier. By developing the electrostatic charge image formed on the image bearing member while applying, a toner image with high image density and high resolution can be formed.

[0070]

EXAMPLES The present invention will be described in more detail below based on examples.

Example 1 Styrene monomer 2000 parts by weight Cyclized rubber 400 parts by weight (Alvex CR450, manufactured by Hoechst Japan) Bontron E81 (charge control agent, manufactured by Orient Chemical Co., Ltd.) 80 parts by weight carbon black (CSX-238, Made by US Cabot Corporation) 600 parts by weight Paraffin wax 155 ° F (softening point 69 ° C) 3500 parts by weight

The above components were heated at a temperature of 80 with an attritor.
A monomer composition was prepared by mixing at 4 ° C. for 4 hours. 254 parts by weight of the obtained monomer composition, 20 parts by weight of amino-modified silica (100 parts by weight of Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.) treated with 5 parts by weight of aminopropyltriethoxysilane) , 0.1N hydrochloric acid (25 parts by weight) and distilled water (1200 parts by weight) were added to an aqueous medium heated to 85 ° C. under stirring by a TK homomixer, and stirred at 10,000 rpm for 15 minutes after the addition. Then, dispersion granulation was performed.

After granulation, the liquid temperature was lowered to 60 ° C., 3 parts by weight of 2,2′-azobis- (2,4-dimethylvaleronitrile) and 2,2′-azobisisobutyronitrile 1 were used as a polymerization initiator. 0.5 part by weight was added to the aqueous medium and stirred for 30 minutes. Further, the stirring was changed to paddle blade stirring, and stirring was carried out at 60 ° C. for 10 hours to complete the polymerization.

The obtained non-magnetic black polymerized toner particle-containing aqueous medium is cooled, dehydrated, washed with a sodium hydroxide solution to dissolve and remove the amino-modified silica, and then further washed with water, dehydrated and dried. (If necessary, fine particles of unnecessary component particles are removed by classification) Number average particle diameter 5 μm (100
A non-magnetic black polymerized toner (measured with a Coulter counter using a μm aperture) was obtained. The obtained non-magnetic black polymerized toner contained about 180 parts by weight of paraffin wax based on 100 parts by weight of polystyrene. Further, the obtained non-magnetic black toner did not cause blocking even if left in an environment of 50 ° C. for one day. From this, it was found that the paraffin wax was encapsulated inside the polymerized toner particles.

The non-magnetic black polymerized toner obtained was observed with an optical microscope to measure the carbon black dispersion ratio.

10 parts by weight of the non-magnetic black polymerized toner obtained above, 0.1 part by weight of zinc stearate powder, hydrophobic silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.)
0.1 part by weight, and 90 parts by weight of insulating magnetic carrier particles having an average particle size of 40 μm (magnetic substance dispersion type resin carrier particles formed by 75 parts by weight of iron trioxide fine powder and 25 parts by weight of epoxy resin). A two-component type developer was prepared by mixing and developed under the following conditions.

As the developing device, the one shown in the drawing was used. The image carrier 1 has a selenium photoconductor 12, the peripheral speed of the image carrier 1 was 100 mm / sec, and the maximum potential of the electrostatic charge image formed on the image carrier 1 was + 750V. The outer diameter of the sleeve (developer carrying member) 2 is 20 m.
m, the peripheral speed is 100 mm / sec, the magnetic flux density in the vertical direction on the sleeve surface of the N and S poles of the magnet roller 3 is 1000 gauss, the thickness of the developer layer (that is, the height of the magnetic brush) is 200 μm, The gap between the sleeve 2 and the image carrier 1 is 300 μm, the bias voltage applied to the sleeve is DC voltage component +200 V, AC voltage component 3.0 KHz, 14
It was 00 Vpp.

The electrostatic latent image is well developed, the developed toner image is electrostatically transferred to plain paper, and the toner image on the plain paper is fixed to a fixing roller having a silicone rubber surface layer under a pressure of 10 kg / cm ^2. And pressure roller fixing device (nip width 7mm, paper speed 150
(mm / sec), the toner image is
Good fixing was performed at a fixing temperature of 100 ° C. (fixing roller surface temperature).

In the developing device of the drawing, the toner T having the external additive is quantitatively supplied to the lower chamber by the supply roller 8 and the elastic member 7 and mixed with the carrier to form the developer 4. To do. A DC bias is applied from the DC bias power source 5 to the sleeve 2 including the magnet roller 3 and the doctor blade 10,
An AC bias is added from the AC bias power supply 6. The developer 4 is conveyed with the rotation of the sleeve 2 in the A direction, and is used for developing the electrostatic latent image on the image carrier 1 including the aluminum cylinder 11 and the selenium photoconductor 12. The developer layer regulating member 9 plays a role of an outer wall of the developing device.

The optical reflection density (Dmax) and the resolution of the image obtained by the above development and fixing are shown in Table 2 below.

Example 2 Paraffin wax 140 ° F. (softening point 60) was used in place of 155 ° F. (3500 parts by weight) of paraffin of Example 1.
C.) 500 parts by weight and paraffin 155.degree. (Softening point 69.degree. C.) 2000 parts by weight, and using the same procedure as in Example 1 except that the liquid temperature of the aqueous medium during dispersion granulation is 90.degree. A polymerized toner having an average particle size of 5 μ was produced. The obtained polymerized toner contained about 125 parts by weight of paraffin wax based on 100 parts by weight of polyethylene. The toner image on plain paper obtained in the same manner as in Example 1 was fixed with the same fixing device as in Example 1 at a fixing temperature of 130 ° C., and a good fixed image was obtained. Dma of this toner
Similarly, x, resolution, and carbon dispersibility are shown in Table 2 below.

Comparative Example 1 Instead of the carbon black CSX-238 used in Example 1, RAVI N1 manufactured by Columbia Carbon Japan Co., Ltd.
4 (particle size 59 mμ, oil absorption by DBP method 111 (cc
The same treatment as in Example 1 was carried out except that 12 g was used, and a toner having a number average particle diameter of 8 μm was obtained, but the granulation conditions (agitation rotation speed, dispersant amount, etc.) were changed. Even if changed, a toner having the same particle size as in Example 1 could not be obtained because the viscosity of the monomer composition was high. Microscopic observation and image formation were carried out in the same manner as in Example 1 using the toner obtained above (fixing temperature was 100 ° C.). (Table 1,
(See 2)

Comparative Example 2 Instead of the carbon black CSX-238 used in Example 1, Printex 35 (particle size 3 made by Degussa, West Germany) was used.
1mμ, oil absorption 43 by DBP method (cc / 100g)
When the same treatment as in Example 1 was carried out except that 12 g was used, a toner having a number average of 5 μm was obtained. Using this toner, microscopic observation and image formation were performed in the same manner as in Example 1. (Fixing temperature was 100 ° C). (See Tables 1 and 2)

The results obtained are shown in Tables 1 and 2 below.

[0085]

[Table 1]

[0086]

[Table 2]

The "fixing temperature" was measured as follows.

<Fixability Test Method> 1) Paper speed 150 mm / sec, paper temperature 25 ± 1 ° C.

2) The pressure of the fixing device is 10 kg / cm ² .

3) Under the pressure of the fixing device, the surface temperature of the fixing roller is raised from 50 ° C. to 55 ° C., 60 ° C., 65 ° C. every 5 ° C. to fix the image.

4) The fixed image is tested by the Kosri test method.

That is, silbon crepe paper (20 g /
m ² ) (manufactured by Kojin Co., Ltd.) are stacked so that the light-selective surface faces downward, and the light-selective surface is pressed against the image surface to be tested with a pressure of 40 g / cm ² , and the crepe paper tear (fiber Indicates the direction)
5 times back and forth in the direction, the ratio of the concentration after the test to the concentration before the test {(concentration after the cost / concentration before the cost) ×
100} is the fixability.

5) The fixing temperature is the lowest temperature at which the fixing property is 80 or more.

[0094]

From the results shown in Tables 1 and 2, the developing method of the present invention uses a two-component developer having a specific non-magnetic black polymerized toner and insulating magnetic carrier particles. It will be understood, however, that by developing an electrostatic charge image while applying an AC bias to the developer carrying member, an image having good image density and resolution can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a specific example of a developing device for carrying out the developing method of the present invention.

[Explanation of symbols]

 1 Photosensitive drum 2 Sleeve 3 Magnet roller 4 Developer 5,6 Development bias power supply 10 Doctor blade

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03G 15/09 G03G 9/08 361 21/10 365 21/00 316

Claims (2)

(57) [Claims] 1. A polymerizable monomer containing (A) (i) at least a styrene monomer and (ii) a number average particle diameter of 40.
~ 300 mμ and 100 oil absorption by DBP method
Carbon black of (cc / 100 g) or less,
(Iii) a polar polymer, a polar copolymer or a cyclized rubber,
(Iv) non-magnetic black polymerized toner particles produced by a suspension polymerization method from a monomer composition containing a low softening point wax having a softening point of 40 to 130 ° C., and (B) insulating magnetic carrier particles. A magnetic brush is formed on the developer carrier with the two-component developer and the electrostatic charge image formed on the image carrier is developed with non-magnetic black polymerized toner particles while applying an AC bias to the developer carrier. A developing method characterized by the above. 2. The developing method according to claim 1, wherein the non-magnetic black polymerized toner particles further contain a charge control agent.