JP3109922B2 - Toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing toner used in electrophotography, electrostatic recording and magnetic recording.

[0002]

2. Description of the Related Art Conventionally, electrophotography has been disclosed in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910.
Many methods are known as described in Japanese Patent Publication No. JP-A-Heisei, 43-24878 and Japanese Patent Publication No. 43-24748. Generally, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means. Forming and then developing the latent image with toner,
After transferring the toner image to a transfer material such as paper as necessary,
The toner is fixed by heating, pressure, heat and pressure, or solvent vapor to obtain a copy, and the toner remaining on the photoreceptor without being transferred is cleaned by various methods, and the above steps are repeated.

In recent years, such copying apparatuses have begun to be used not only as office work copying machines for simply copying original documents, but also as printers as personal computer outputs or personal copying machines for individuals. .

[0004] For this reason, smaller, lighter, faster, and more reliable devices have been strictly pursued, and machines have become simpler in various respects. As a result, the performance required of the toner has become higher, and if the performance of the toner cannot be improved, a better machine cannot be realized.

As a developing method for developing an electrostatic charge image, various developing methods using a one-component developer consisting of toner alone have been proposed. Among them, a method using a developer consisting of magnetic toner particles has been proposed. Many are excellent.

[0006] However, such a developing method is characterized by a simple, light and small developing device, and conversely, the toner used in this method has excellent image quality unless the charged state is more stable than that of the conventional toner. Durability and stability cannot be obtained. That is, the performance of the magnetic material is often directly reflected on the performance of the toner.

[0007] Among the materials used for the magnetic toner, the magnetic substance is particularly 20 to 70% by weight based on the whole magnetic toner.
The content greatly affects the performance of the magnetic toner.

Japanese Patent Application Laid-Open No. Sho 56-104336 discloses a magnetic toner using a cubic magnetic material.
Japanese Patent Application Laid-Open No. 9-64852 discloses a magnetic toner using a spherical or rounded magnetic material.

Japanese Patent Application Laid-Open Nos. 3-101743 and 3-101744 disclose reducing the size of magnetic particles to make the magnetic toner particles uniform.

However, even if such a magnetic material is used, a sufficient effect cannot be obtained unless it is uniformly dispersed in the toner particles. Further, when the magnetic material particles become smaller, the amount of the magnetic material exposed on the toner surface increases, and the polishing action of the toner particles increases. Therefore, when an organic photoreceptor is used, there is a problem that the shaving amount of the photosensitive drum is increased, and the life may be shortened.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner for developing an electrostatic image, which solves the above-mentioned problems.

That is, an object of the present invention is to provide a toner for developing an electrostatic image, which is excellent in developability and durability.

It is a further object of the present invention to provide a toner for developing an electrostatic charge image which prevents abrasion of an organic photoreceptor and gives a stable image.

It is still another object of the present invention to provide an electrostatic image developing toner which does not cause filming or fusion.

[0015]

The object of the present invention is achieved by the following constitution.

That is, the present invention provides at least a binder resin,
In a toner for developing an electrostatic image containing a wax and a magnetic substance, the magnetic substance has an average particle diameter of 0.2 μm or less, the wax has a penetration of 4 or less, and a density of 0.93 or more. And a wax having a melt viscosity at 140 ° C. of 200 cP or less and a ratio (Mw / Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) of 3 or less. The present invention relates to a toner for developing a charge image.

The average particle size of the magnetic material as used herein refers to a value obtained by magnifying a 10,000-fold photograph of a magnetic material obtained by a transmission electron microscope four-fold to obtain a 40,000-fold photograph. To 30
Zero magnetic bodies are selected, their diameters are actually measured by a digitizer, and the number average is determined from the diameters and the numbers.
The diameter is a horizontal fly diameter.

As a result of diligent research conducted by the present inventors, the particle size of the magnetic material was determined to be stable in toner charging during development,
It has been found that it is related to the selectivity of the toner for development and the fixing property.

In particular, even in a situation where a developing sleeve which is a charging member for toner is strongly frictionally charged,
Control can be performed so that the charge amount does not increase more than necessary. This is more than conventionally used.
By using a magnetic substance having a small particle size and having a uniform particle size distribution, more magnetic substance particles are present near the surface of the toner than the conventional toner, so even if the toner surface is viewed microscopically, This is to make them even. In other words, when the toner is frictionally charged with the developing sleeve, in the conventional toner, if the portion in contact with the sleeve is a place where there is no magnetic material on the toner surface, the charge on the toner surface is increased accordingly, and the toner with uneven charge is Becomes If the same effect is to be obtained by increasing the content of the magnetic substance, the magnetic force of one toner also increases, so that the toner hardly separates from the developing sleeve, resulting in a decrease in image density and a deterioration in fixability, and the like. Not preferred.

Therefore, in the present invention, the magnetic material is 0.2
It is necessary to have an average particle diameter of 0.1 μm or less, preferably 0.10 to 0.20 μm, and more preferably 0.14 μm to 0.19 μm.
It preferably has an average particle size of μm.

When the average particle size of the magnetic material is larger than 0.2 μm, the particle size distribution becomes wide, and the distribution of the magnetic material in the toner tends to be non-uniform. It is difficult to stably maintain image density and fog prevention for a long period of time. Also, when the average particle size of the magnetic material is extremely small, the color of the magnetic material tends to be reddish, and the cohesive force is large and it is difficult to loosen. Etc. may be a problem.

The magnetic material according to the present invention preferably has a bulk density of 1.0 g / cm ³ or less, more preferably 0.9 g / cm ³ or less, and even more preferably 0.2 g / cm ³ or less.
0.8 g / cm ³ , even more preferably 0.3 to 0.7
g / cm ³ is good.

When the bulk density of the magnetic material is greater than 1.0 g / cm ³ , the magnetic material is unevenly distributed due to the difference in bulk density between the magnetic material and the binder resin powder when mixed with the binder resin powder before melt-kneading. Easy to happen.

If the magnetic material is unevenly distributed during the mixing before the melt-kneading, toner particles having different magnetic material contents are generated, and as a result, fog increases.

The bulk density of the magnetic material is measured according to JIS-K51.
Perform according to 01.

The magnetic material according to the present invention is 16 cc / 1.
It preferably has an oil absorption of 00 g or more, more preferably 18 cc / 100 g.

When the oil absorption of the magnetic material is less than 16 cc / 100 g, the dispersibility in the binder resin tends to decrease.

For measuring the oil absorption of the magnetic material, linseed oil is dropped by taking a fixed amount of sample as a glass plate, and the minimum linseed oil amount when the sample becomes a paste is defined as the oil absorption.

Further, the magnetic material according to the present invention is 6.0 m ^2.
/ G or more, and more preferably 6.5 m ² / g or more.

The BET specific surface area of the magnetic material is 6.0 m ² / g
If it is less than 3, the density tends to decrease due to excessive charging under low humidity.

The BET specific surface area can be determined by a BET multipoint method using nitrogen as an adsorbed gas, and the sample is degassed at 100 ° C. for one hour as a pretreatment (for example, a product made by Yuasa Ionics, Inc.). An automatic gas adsorption amount measuring device, Autosorb 1, can be used).

The magnetic material used in the present invention is selected from ferromagnetic metal particles such as iron, cobalt and nickel, or ferromagnetic iron oxide particles such as magnetite, maghemite and ferrite, iron, cobalt, nickel and manganese. There are two or more ferromagnetic alloy particles.

From among such magnetic materials, magnetite will be described.

Magnetite is prepared by mixing a ferrous salt solution and an alkaline aqueous solution to form a suspension containing ferrous hydroxide at a temperature of 70 to 100 ° C. and a pH of 10 or more. Obtained by venting gas. The shape of magnetite particles can be adjusted by selecting the production conditions.
A polyhedral magnetic material such as a sphere, hexahedron, and octahedron can be obtained.

The alkaline aqueous solution includes sodium hydroxide,
Alkali metal hydroxides such as potassium hydroxide and alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide can be used.

In a suspension containing ferrous hydroxide, a water-soluble silicate such as sodium silicate or potassium silicate (0.1 to ₂ .
0% by weight) is preferable because the particle size of the generated magnetite can be further improved.

A temperature containing 70 to 100 ° C. containing ferrous hydroxide obtained by mixing an aqueous alkaline solution and an aqueous ferrous salt solution;
When an oxygen-containing gas is passed through a suspension having a pH of 10 or more while heating, small magnetite particles having a fine particle size and a sharp particle size distribution can be obtained.

The amount of the magnetic substance contained in the toner is preferably about 20 to 200 parts by weight, particularly preferably 40 to 150 parts by weight, per 100 parts by weight of the resin component.

The magnetic characteristics when a 10 K Oersted is applied have a coercive force (Hc) of 20 to 300 Oersted saturation magnetization (σ
s) 50-200 emu / g, residual magnetization (σr) 2-2
Those having 0 emu / g are preferred.

It is also preferable to subject the magnetic material to compaction and pulverization in order to obtain an appropriate bulk density and oil absorption.

The wax used in the present invention is obtained from the following wax.

Paraffin wax and its derivatives, montan wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives, polyalkylene wax and its derivatives, etc. The derivatives include oxides and vinyl monomers. Including block copolymers and graft-modified products.

In addition, alcohols, fatty acids, acid amides,
Esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, animal waxes, mineral waxes, petrolactam and the like can also be used.

Among them, waxes which are particularly preferably used include a low-molecular-weight alkylene polymer obtained by radical polymerization of alkylene under high pressure or a Ziegler catalyst under low pressure, and an alkylene polymer obtained by thermally decomposing a high-molecular weight alkylene polymer. A wax obtained from the distillation residue of hydrocarbons obtained from the synthesis gas consisting of carbon monoxide and hydrogen by the Age method, or from a synthetic hydrocarbon obtained by hydrogenating them, and an antioxidant is added. It may be.

According to the present invention, a wax obtained by separating a wax from these waxes by molecular weight using a press sweating method, a solvent method, vacuum distillation, fractional crystallization (for example, melt liquid crystal precipitation and crystal filtration can be used) or the like. Used for After fractionation, oxidation, block copolymerization, or graft modification may be performed.

That is, those obtained by removing low molecular weight components by these methods, those obtained by extracting low molecular weight components, and those obtained by removing low molecular weight components therefrom.

The most preferred wax as a base is a metal oxide-based catalyst (often a multicomponent system of two or more types).
Those synthesized by the reaction of carbon monoxide and hydrogen, for example, the carbon number obtained by the Zintall method, the hydrochol method (using a fluidized catalyst bed), or the Age method (using a fixed catalyst bed) that yields a large amount of waxy substances Of hydrocarbons (particularly preferred are those obtained by hydrogenation to obtain the target product) or hydrocarbons obtained by polymerizing alkylenes such as ethylene with a Ziegler catalyst, having a small number of branches and a long, saturated linear hydrocarbon. Hydrogen. In particular, a hydrocarbon wax synthesized by a method that does not rely on the polymerization of alkylene is preferable because of its structure and a molecular weight distribution that can be easily separated.

By using a wax fractionated from such a wax by molecular weight, it is possible to improve the dispersibility of the magnetic substance and reduce the adverse effect on the blocking resistance.

This is because more components that effectively exert the effects described below can be used as wax.

The wax according to the present invention has a number average molecular weight (Mn) and a weight average molecular weight (Mw) in the molecular weight distribution.
(Mw / Mn) must be 3 or less, preferably 2.5 or less, and more preferably 2.0 or less. The number average molecular weight (Mn) is 300 to 120.
0, more preferably 350 to 10
00 and a weight average molecular weight (Mw) of 50
It is preferably 0 to 3600, more preferably 5
It is good to be 50-3000. By giving such a molecular weight distribution, wax can be given favorable physical characteristics.

The wax used in the present invention is 200 c
It is characterized by having a melt viscosity at 140 ° C. of not more than P, preferably not more than 100 cP, more preferably not more than 50 cP.
cP or less.

Since the wax of the present invention has a low melt viscosity, the magnetic material of the present invention can be well dispersed in a binder resin during melt kneading. That is, since the particle diameter of the magnetic material is small, aggregates are easily formed, but the molten wax is absorbed into the aggregates, so that the wettability to the binder resin is increased, and the wax is easily loosened. Therefore, when the melt viscosity of the wax is small and the oil absorption of the magnetic substance is large, the dispersibility becomes the best. 140 of wax
If the melt viscosity at 200 ° C. exceeds 200 cP, the absorption efficiency in the agglomerate will be poor, and it will be difficult to exhibit the dispersion effectively.

That is, the magnetic material of the present invention is sufficiently dispersed in the binder resin, and the developability and durability of the magnetic toner can be improved. However, when the magnetic material having a small particle diameter is sufficiently dispersed, a large amount of the magnetic material is uniformly exposed on the surface of the toner, so that the polishing action becomes strong and the organic photoconductor is easily scraped.
The wax of the present invention is characterized by having a penetration of 4 or less, preferably 3 or less, and a density of 0.93 or more, preferably 0.94 or more.
The cleaning property can be improved, and the shaving of the organic photoreceptor can be reduced. Further, it preferably has a crystallinity of 80% or more, more preferably 85%.
That is all.

When the wax has a density of at least 0.93, preferably at least a crystallinity of at least 80%, the wax can be dispersed so as to effectively give the toner a slippery property. That is, it is considered that the particles are dispersed with an appropriate size on the toner surface. Also, if the penetration exceeds 4,
If the density is less than 0.93 or the degree of crystallinity is less than 80%, it is not preferable because not only the effect is hardly obtained but also the fusion easily occurs on the photoreceptor.
Further, the wax preferably has a softening point of 130 ° C or lower, more preferably 120 ° C or lower. When the softening point of the wax exceeds 130 ° C., the offset resistance is affected.

Further, the wax used in the present invention is:
In the DSC curve measured by the differential scanning calorimeter, the onset temperature of the endothermic peak at the time of temperature rise is 50 to 110 ° C.
Is preferably within the range.

At the time of raising the temperature, the change when heat is applied to the wax can be seen, and an endothermic peak accompanying the transition melting of the wax is observed. Peak onset temperature is 50-11
When the temperature is within the range of 0 ° C., developability, blocking resistance, and low-temperature fixability can be satisfied. When the peak onset temperature is less than 50 ° C., the change temperature of the wax is too low, the blocking resistance is poor, and the toner tends to be poor in developability at the time of temperature rise. Is too high, and sufficient fixability cannot be obtained.

In the DSC measurement according to the present invention, since the exchange of heat of the wax is measured and its behavior is observed, it is preferable to measure with a highly accurate internal heating input compensation type differential scanning calorimeter from the measurement principle. DSC-7 manufactured by Perkin Elmer, Inc. can be used.

The measuring method is ASTM D3418-82.
Perform according to. The DSC curve used in the present invention is obtained by raising and lowering the temperature once, taking a pre-history, and then setting the temperature rate to 10 ° C./mi.
The DSC curve measured when the temperature is raised at n is used. The definition of each temperature is defined as follows.

Onset temperature of endothermic peak The temperature at the intersection of the tangent of the curve and the base line at the point where the differential value of the DSC curve at the time of temperature rise is first maximized.

In the present invention, the molecular weight distribution of the hydrocarbon wax is determined by gel permeation chromatography (G
PC) under the following conditions.

(GPC measurement conditions) Apparatus: GPC-150
C (Waters) Column: GMH-HT 30 cm 2 columns (manufactured by Tosoh Corporation) Temperature: 135 ° C Solvent: o-dichlorobenzene (0.1% ionol added) Flow rate: 1.0 ml / min Sample: 0.15% sample 0.4 ml injection

Measurement is performed under the above conditions, and the molecular weight of the sample is calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample. In addition, Mark-Hou
It is calculated by performing a conversion according to the wax such as a polyethylene conversion using a conversion formula derived from the win viscosity formula.

The penetration of waxes in the present invention is J
It is a value measured according to IS K-2207. Specifically, it is a numerical value representing the penetration depth when a needle having a conical tip having a diameter of about 1 mm and a vertex angle of 9 ° is penetrated with a constant load in a unit of 0.1 mm. The sample conditions in the present invention are a sample temperature of 25 ° C., a load of 100 g, and a penetration time of 5 seconds.

The melt viscosity is a value measured using a Brookfield type viscometer.
40 ° C., shear rate 1.32 rpm, sample 10 ml. The softening point is a value measured according to JIS K2207.

The crystallinity is determined by X-ray diffraction.
The diffraction pattern by the crystal becomes a sharp peak, and the scattering by the amorphous becomes a very broad halo. When both crystalline and amorphous are present, the ratio of crystalline to the entire sample is referred to as crystallinity. The total X-ray scattering intensity (intensity of coherent scattering excluding Compton scattering) is always constant irrespective of the quantitative ratio between crystalline and amorphous. Therefore, the crystallinity χ (%) is obtained by the following equation.

Χ (%) = Ic / (Ic + Ia) × 100 Ic: peak area of scattering intensity of crystalline portion of unknown sample Ia: peak area of scattering intensity of amorphous portion of unknown sample

The content of these hydrocarbon waxes is within 20 parts by weight based on 100 parts by weight of the binder resin.
It is effective to use 0.5 to 10 parts by weight, and it may be used in combination with other waxes.

As the binder resin used in the toner of the present invention, the following binder resins can be used.

For example, homopolymers of styrene such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene and their substituted products; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene Copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer -Based copolymer; polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin , Xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin and the like can be used. Preferred binders include styrene copolymers or polyester resins.

Examples of comonomers for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and the like.
Double such as dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. A monocarboxylic acid having a bond or a substituted product thereof;
For example, dicarboxylic acids having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and the like;
Vinyl esters such as vinyl acetate and vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; vinyl methyl ether and vinyl Vinyl monomers such as ethyl ether, vinyl isobutyl ether and the like; and vinyl monomers such as one or two or more are used.

The styrene-based polymer or styrene-based copolymer may be cross-linked, or may be used as a mixture with another resin.

As a crosslinking agent for the binder resin, a compound having two or more polymerizable double bonds may be mainly used, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene, etc .; Carboxylic acid esters having two double bonds such as diacrylate, ethylene glycol dimethacrylate, 1,3-butadiol dimethacrylate; divinylaniline, divinyl ether, divinyl sulfide;
A divinyl compound such as divinyl sulfone; and a compound having three or more vinyl groups are used alone or as a mixture.

In the toner of the present invention, it is preferable that a charge control agent is blended (internally added) to toner particles or mixed (externally added) with toner particles. The charge control agent makes it possible to control the amount of charge optimally according to the development system. In particular, in the present invention, the balance between the particle size distribution and the charge can be further stabilized. Examples of the positive charge controlling agent include denatured products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonic acid and tetrabutylammonium tetrafluoroborate, and analogs thereof. Onium salts such as phosphonium salts and the like, lake pigments thereof, triphenylmethane dyes and these lake pigments, (phosphorus tungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic Acid, ferricyanide, ferrocyanide, etc.) Metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borane DOO, diorgano tin borate such as dicyclohexyl tin borate; can be used in combination singly or two or more kinds. Among these, charge control agents such as nigrosine, quaternary ammonium salts, and triphenylmethane pigments are particularly preferably used.

Further, the general formula

[0075]

[Outside 1] [R ₁ : H, CH ₃ R ₂ , R ₃ : a substituted or unsubstituted alkyl group (preferably C ₁ -C ₄ )] homopolymer of a monomer: styrene, acrylate, methacrylic acid described above A copolymer with a polymerizable monomer such as an ester can be used as a positive charge control agent. In this case, these charge control agents also act as (all or part of) the binder resin.

As the negative charge control agent, there are the following substances.

For example, organic metal complexes and chelate compounds are effective, and examples thereof include monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

The above-mentioned charge control agent (having no function as a binder resin) is preferably used in the form of fine particles. In this case, the number average particle size of the charge control agent is
Specifically, it is preferably 4 μm or less (more preferably 3 μm or less).

When internally added to the developer, such a charge control agent is preferably used in an amount of 0.1 to 20 parts by weight (more preferably 0.2 to 10 parts by weight) based on 100 parts by weight of the binder resin. .

In the toner of the present invention, charging stability,
In order to improve developability, fluidity and durability, it is preferable to add silica fine powder.

The silica fine powder used in the present invention is BE
The specific surface area by nitrogen adsorption measured by the T method is 30 m ² / g
Those within the above range (particularly 50 to 400 m ² / g) give good results. It is preferable to use 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight of silica fine powder with respect to 100 parts by weight of the toner.

The silica fine powder used in the present invention is:
Silicon varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, silane coupling agents having functional groups, and other organosilicon compounds for purposes such as hydrophobicity and charge control, if necessary It is also preferable that the composition is treated with such a treating agent or in combination with various treating agents.

As other additives, lubricant powders such as, for example, Teflon powder, zinc stearate powder, and polyvinylidene fluoride powder, among which polyvinylidene fluoride is preferable.
Alternatively, abrasives such as cerium oxide powder, silicon carbide powder, and strontium titanate powder, among which strontium titanate is preferred. Or, for example, titanium oxide powder,
Fluidity-imparting agents such as aluminum oxide powder, particularly hydrophobic ones are preferred. A small amount of a caking inhibitor, a conductivity imparting agent such as a carbon black powder, a zinc oxide powder, an antimony oxide powder, a tin oxide powder, and the like, and fine particles of white and black having opposite polarities can also be used as a developing property improver.

To prepare the toner for developing an electrostatic image according to the present invention, a binder resin, a wax, a metal salt or a metal complex, a pigment or dye as a colorant, a magnetic substance, a charge control agent if necessary, While the other additives, etc. were thoroughly mixed by a mixer such as a Henschel mixer, a ball mill, and then melt-kneaded using a heat kneader such as a heating roll, a kneader, or an extruder to make the resins compatible with each other. The toner according to the present invention can be obtained by dispersing or dissolving a metal compound, a pigment, a dye, and a magnetic substance, and performing cooling and solidification followed by pulverization and classification.

Further, if necessary, desired additives are sufficiently mixed with a mixer such as a Henschel mixer to obtain a toner for developing an electrostatic image according to the present invention.

[0086]

The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples. First, the magnetic substance and wax used in the present invention will be described.

Various magnetic materials were obtained by changing the magnetite generation conditions and post-treatment conditions, and the physical properties are shown in Table 1.

A wax A and a wax B were obtained by fractional crystallization from the wax synthesized by the Age method. Using a Ziegler catalyst, ethylene was subjected to low pressure polymerization to obtain a wax having a relatively low molecular weight, and a low molecular weight fraction was removed to some extent by molecular weight fractionation to obtain wax C. Wax D was obtained from the thermal decomposition of the polyalkylene. These physical properties are shown in Tables 2 and 3.

[0089]

[Table 1]

[0090]

[Table 2]

[0091]

[Table 3]

Example 1 100 parts by weight of styrene-butyl acrylate copolymer 80 parts by weight of magnetic substance (1) 2 parts by weight of nigrosine 4 parts by weight of wax (A) Melt kneading was performed by a shaft kneading extruder. After cooling, the kneaded material was coarsely pulverized, finely pulverized by a pulverizer using a jet stream, and further classified using an air classifier to obtain a toner having a weight average particle diameter of 8 μm. 0.6 part by weight of positively charged hydrophobic colloidal silica was externally added to 100 parts by weight of the above toner.

Various evaluations were performed using the toner obtained in a commercially available electrophotographic copying machine NP-1215 (manufactured by Canon Inc.). The results are shown in Table 4.

(Durability test) A durability test was performed on 20,000 sheets in an environment of 10% humidity and a temperature of 15 ° C, and the image density, fogging, filming and fusing of external additives, the amount of scraping of the photosensitive drum (film thickness) If the difference is 4.0 μm or less per 20,000 sheets, it can be practically used).

(Blocking Test) Approximately 20 g of the developer was placed in a 100 cc plastic cup, left at 50 ° C. for 3 days, and evaluated visually.

Excellent: No aggregates were observed Good: Aggregates were observed but easily collapsed Good: Aggregates were observed but collapsed when shaken Impossible: Aggregates could be grasped and not easily collapsed

Example 2 100 parts by weight of styrene-butyl acrylate copolymer 80 parts by weight of magnetic substance (2) 2 parts by weight of nigrosine 4 parts by weight of wax (B) Using the above materials, a toner was prepared in the same manner as in Example 1. It was prepared and evaluated, and the results are shown in Table 4.

Example 3 100 parts by weight of styrene-butyl acrylate copolymer 80 parts by weight of magnetic substance (3) 2 parts by weight of nigrosine 4 parts by weight of wax (C) Using the above materials, a toner was prepared in the same manner as in Example 1. It was prepared and evaluated, and the results are shown in Table 4.

Example 4 100 parts by weight of styrene-butyl acrylate copolymer 80 parts by weight of magnetic substance (4) 2 parts by weight of nigrosine 4 parts by weight of wax (A) Using the above materials, a toner was prepared in the same manner as in Example 1. It was prepared and evaluated, and the results are shown in Table 4.

Example 5 100 parts by weight of styrene-butyl acrylate copolymer 80 parts by weight of magnetic substance (5) 2 parts by weight of nigrosine 4 parts by weight of wax (B) Using the above materials, a toner was prepared in the same manner as in Example 1. It was prepared and evaluated, and the results are shown in Table 4.

Comparative Example 1 100 parts by weight of styrene-butyl acrylate copolymer 80 parts by weight of magnetic material (6) 2 parts by weight of nigrosine 4 parts by weight of wax (C) Using the above materials, a toner was prepared in the same manner as in Example 1. It was prepared and evaluated, and the results are shown in Table 4.

Comparative Example 2 100 parts by weight of styrene-butyl acrylate copolymer 80 parts by weight of magnetic substance (1) 2 parts by weight of nigrosine 4 parts by weight of wax (D) Using the above materials, a toner was prepared in the same manner as in Example 1. It was prepared and evaluated, and the results are shown in Table 4.

[0103]

[Table 4]

[0104]

According to the present invention, there is provided a toner for developing an electrostatic charge image which does not cause filming or fusion while preventing shaving of the organic photoreceptor, has excellent developability and durability, and is always sharp. Image can be given.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Kawakami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masaji Fujiwara 3-30-2 Shimomaruko, Ota-ku, Tokyo (56) References JP-A-56-29249 (JP, A) JP-A-3-139664 (JP, A) JP-A-3-91764 (JP, A) JP-A-3-1311863 (JP) , A) JP-A-56-27156 (JP, A) JP-A-3-131864 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (1)

(57) [Claims] 1. An electrostatic image developing toner containing at least a binder resin, a wax and a magnetic material, wherein the magnetic material has an average particle size of 0.2 μm or less, and the wax has a particle size of 4 or less. Penetration, density above 0.93 and 200c
Has a melt viscosity at 140 ° C. of P or lower, and
Ratio between number average molecular weight (Mn) and weight average molecular weight (Mw)
(Mw / Mn) is a wax having a molecular weight of 3 or less .