JP2001318486A - Toner for nonmagnetic single-component development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for nonmagnetic single-component development which causes little fogging, which is excellent in reproducibility for a black solid and in image characteristics with good transferrability when the toner is used for a device for nonmagnetic single-component development. SOLUTION: The toner for nonmagnetic single-component development contains alumina particles having >=90 wt.% Al2O3 content depositing on the surfaces of toner particles containing at least a binder resin and a coloring agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic one-component developing toner used for developing an electrostatic latent image formed on a photoreceptor by electrophotography or the like.

[0002]

2. Description of the Related Art Conventionally, developing methods used in electrophotography and the like include insulating fine powder mainly composed of a binder resin,
That is, a two-component developing method in which an insulating toner and a magnetic carrier are charged by friction to develop an electrostatic latent image formed on a photoreceptor with a magnetic brush, and a magnetic one-component developing with a one-component toner consisting of only magnetic toner A so-called non-magnetic one-component developing method in which a developing method and a toner are formed in a thin layer on a developing sleeve and developed with or without contact with a photoreceptor is known. In the non-magnetic one-component developing method, it is necessary to impart a sufficient amount of charge to the toner, as in the two-component developing method, in order to obtain a good visible image, and the thickness of the toner on the developing sleeve is reduced. It is essential to have uniform control. In order to obtain such characteristics, a rubber or metal blade member is often used by pressing against the developing sleeve for the purpose of regulating the toner layer and imparting charge to the toner. It has also been proposed that the toner is provided with a relatively high charge by including a charge control agent such as a gold-containing azo dye.

However, if the pressing force of the blade member pressed against the developing sleeve is low, there is a problem that sufficient charge is not applied to the toner and a sufficient image density cannot be obtained, or that fog is large and the toner consumption is large. I was Conversely, if the pressure contact force is high, the surface of the blade member and the developing sleeve becomes significantly worn during repeated development, and irregularities are generated on those surfaces. The amount of charge required by the toner becomes insufficient due to the uneven force applied when passing through, or the developer layer becomes partially thicker, causing density unevenness and fog on the image. I was letting it. Further, a phenomenon in which the toner is fused to the developing sleeve by a pressing force or heat, that is, so-called sleeve fusion may occur. Also, if a large amount of untransferred toner remains on the photoconductor on which the latent image is formed, the pressing force of the cleaning member that presses against the photoconductor increases, and a filming phenomenon occurs in which the toner is fused to the photoconductor surface. There was something.

In recent years, environmentally friendly organic semiconductors are frequently used for the above-mentioned photoreceptors when they are disposed of. In this case, in a printer using a negative polarity organic photoreceptor, a negative polarity corona discharge based on reversal development and a negative polarity toner are used,
Positive polarity toners are often used for positive polarity photoconductors. Conventionally, in a non-magnetic one-component developing method based on reversal development using such an organic photoreceptor, image density,
There were problems such as fogging, chargeability, transfer efficiency, reproducibility of solid black in continuous printing, and fusion of a sleeve. JP-B-53-22447 uses aminosilane-treated metal oxide fine powder to assist in imparting polarity to toner. JP-A-58-216252 discloses metal oxide fine powder treated with aminosilane and a hydrophobizing agent. Japanese Patent Laid-Open No. 2-1
Japanese Patent No. 35461 discloses a technique such as toner using a fine silica powder treated with an aminosilane coupling agent having a specific tertiary amino group.
There has been proposed a technology for a high-quality toner free from fog and ghost by using silica particles having different particle diameters in combination. However, at present, practically sufficient characteristics have not yet been obtained by the above-mentioned conventional technology.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem of the conventional non-magnetic one-component developing system. In the non-magnetic one-component developing system, image density unevenness and fog are reduced. It is an object of the present invention to provide a non-magnetic one-component developing toner having a small toner consumption and a high transfer efficiency.

[0006]

According to the present invention, alumina particles having an Al ₂ O ₃ content of 90% by weight or more adhere to the surface of toner particles containing at least a binder resin and a colorant. And a non-magnetic one-component developing toner.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The alumina particles used in the non-magnetic one-component developing toner of the present invention must have an Al ₂ O ₃ content of 90% by weight or more. With alumina particles having an Al ₂ O ₃ content of less than 90% by weight, it is not possible to obtain a non-magnetic one-component developing toner having less image density unevenness and fog. Further, alumina particles having an Al ₂ O ₃ content of 99% by weight or more are preferable in order to obtain a non-magnetic one-component developing toner having a lower toner consumption and a higher transfer efficiency.

Alumina particles having an Al ₂ O ₃ content of 90% by weight or more are obtained by obtaining aluminum hydroxide or transition alumina from bauxite, which is a raw material, and calcining the aluminum hydroxide or transition alumina in the air to obtain alumina particles. Bayer method for obtaining particles, hydrothermal treatment method for hydrothermally treating aluminum hydroxide to obtain alumina particles, flux method for adding and melting flux of aluminum hydroxide to obtain alumina particles, mineralization of aluminum hydroxide And baking in the presence of an agent to obtain alumina particles. In the Bayer method, when sintering aluminum hydroxide or transition alumina in the atmosphere, high-concentration hydrogen chloride gas or the like is used to sinter at a high temperature to obtain alumina particles containing a large amount of Al ₂ O _3. Can be. The Al ₂ O ₃ content of the alumina particles can be measured by a fluorescent X-ray quantitative analysis method or the like. The volume average particle size of the alumina particles is 0.2 to 5μ.
m is preferable. The surface of the alumina particles may be treated with a surface treating agent used for hydrophobic silica particles described below. It is preferable that the alumina particles be attached in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the toner particles. When the amount is less than 0.01 part by weight, it is difficult to make the frictional charging properties of the individual toner particles uniform, so that it is difficult to obtain a toner for non-magnetic one-component development with a small amount of toner consumption and good transfer efficiency. It is difficult to obtain the effect of reducing unevenness and fog.

In the present invention, it is preferable that hydrophobic silica particles and magnetic powder adhere to the surface of the toner particles together with the alumina particles. By adhering the hydrophobic silica particles and the magnetic powder to the surface of the toner particles together with the alumina particles, the triboelectrification of the individual toner particles is made uniform, and as a result, image density unevenness and fog are reduced, and toner consumption is reduced. It is possible to obtain a non-magnetic one-component developing toner having a small amount and high transfer efficiency.

The hydrophobic silica particles are silica particles which have been surface-treated with a surface treatment agent such as aminosilane, silicone oil having an amine in a side chain, a silane coupling agent, a titanium coupling agent and the like. The aminosilane may be represented by the following formula: X _m SiY _n (where X is an alkoxy group or a halogen atom, and m is 1
An integer of 1 to 3, Y is a hydrocarbon group having a primary to amino group, n is an integer of 1 to 3, and m + n is 4 or less. ) And the following compounds can be exemplified.

Embedded image Or a polyaminoalkyl trialkoxysilane can be exemplified, and these may be used alone or in a mixture of two or more.

The silicone oil having an amine in the side chain is represented by the following formula:

Embedded image (In the formula, R ₁ represents a hydrogen, an alkyl group, an aryl group or an alkoxy group, R ₂ represents an alkylene group or a phenylene group, and R ₃ and R ₄ represent a hydrogen, an alkyl group or an aryl group, provided that the alkyl is The group, the aryl group, the alkylene group and the phenylene group may contain an amine, and may have a substituent such as halogen as long as the chargeability is not impaired.) Silicone oil having an amine in the side chain can be obtained as a commercial product, for example, the following structural formula

Embedded image(Where R₁And R_FiveAre independently of each other an alkyl group or
Represents an aryl group; _TwoIs an alkylene group, phenylene
A group or an alkyl group containing an amine,_ThreeIs hydrogen,
Represents an alkyl group or an aryl group, and m and n are 1 or more
Indicates the above integer. ) Is modified silicone oil
It is preferably used.

A silane coupling agent is an organosilicon monomer having two or more different reactive groups in a molecule. One of the two reactive groups is a reactive group that chemically bonds to an inorganic substance (for example, a methoxy group). , An ethoxy group, a cellosolve group, etc.)
The other is a reactive group (for example, an amino group) that chemically bonds to the organic material. Amino group-containing silane coupling agents are particularly preferred, and examples of these compounds include the following. N-β (aminoethyl) -γ aminopropyltrimethoxysilane, N-β (aminoethyl) -γaminopropylmethyldimethoxysilane, γaminopropyltriethoxysilane, N-phenyl-γaminopropyltrimethoxysilane and the like. The following are examples of manufacturers and trade names that are commercially available as silica surface-treated with the above-mentioned surface treating agent. RA200 manufactured by Aerosil Japan
HS, HVK2115, HVK2150 manufactured by Hoechst
etc.

The hydrophobic silica particles may be those obtained by treating silica particles with an organosilane-based surface treating agent such as dimethyldichlorosilane, hexamethyldisilazane, octyltrimethoxysilane, or the like. Are R-972 and R-97 manufactured by Nippon Aerosil Co., Ltd.
4, R-976, R-811, R-812, R-80
5, R-202, RX-170, and the like, and those sold under the trade names such as Taranox 500 manufactured by Talco, H2000 manufactured by Hoechst, and TS-530 manufactured by Cabot. It is preferable that the hydrophobic silica particles are attached in an amount of 0.01 to 1.5 parts by weight based on 100 parts by weight of the toner particles. When the amount is less than 0.01 part by weight, the effect of reducing image density unevenness and fogging is hardly obtained, and when the amount is more than 1.5 parts by weight, it is difficult to make the triboelectrification of individual toner particles uniform, so that toner consumption is small and transfer efficiency is low. It is difficult to obtain a good non-magnetic one-component developing toner.

Preferably, the magnetic powder has a size of 0.3 to 3 μm as determined by particle analysis using an electron microscope. The magnetic powder having a particle diameter of 0.3 to 3 μm may be directly attached to the surface of the toner particles. Alternatively, a commercially available magnetic powder has a primary particle size of 0.1.
2 to 0.4 μm, and 5 to 1 depending on a plurality of primary particles.
Since an aggregate of 0 μm is formed, the magnetic powder forming the aggregate may be deflocculated by a mixer such as a Henschel mixer and then adhered to the surface of the toner particles.

The shape of the magnetic powder used in the present invention is preferably spherical so as not to damage the photosensitive drum when the magnetic powder separates from the toner particles. If the amount of the magnetic powder is too large, scratches on the photoreceptor drum will increase, and if the amount is small, it will not contribute to the improvement of the charging property. Preferably, there is. As such magnetic powder,
Compounds such as iron, cobalt, nickel, manganese, and zinc, such as magnetite, hematite, and ferrite, and specifically, EPT-500 and EPT manufactured by Toda Kogyo Co., Ltd.
-1000, BL-220 and BL-2 manufactured by Titanium Industry Co., Ltd.
00, KBC-100L manufactured by Kanto Denka Co., Ltd. and the like.

As a method for attaching the alumina particles, the hydrophobic silica particles and the magnetic powder to the toner particles, a method using a general stirrer such as a turbine type stirrer, a Henschel mixer, a super mixer, or an apparatus called a surface reformer is used. (Nara Hybridization System manufactured by Nara Machinery Co., Ltd., Angmill manufactured by Hosokawa Micron Corporation, etc.). The alumina particles, the hydrophobic silica particles, and the magnetic powder on the surface of the toner particles may be formed in a weakly adhered state called a glare to the toner particles, or each of the particles may be partially embedded in the toner particles. It may be formed in the adhered state and fixed.

The toner particles of the present invention contain at least a binder resin and a colorant, and further contain an anti-offset agent such as polypropylene and polyethylene, a charge controlling agent, a lubricant for improving fluidity, and the like as appropriate. The diameter is in the range of 5 to 20 μm, which is produced by a melt-kneading pulverization method or a polymerization method. Examples of the binder resin include styrenes such as styrene, α-methylstyrene, and chlorostyrene; and acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, and alkyl acrylate. Kind,
Methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, stearyl methacrylate, glycidyl methacrylate, alkyl methacrylate, acrylonitrile, maleic acid, maleic acid ester, methacrylic acid Homopolymerized vinyl monomers such as methyl, methyl acrylate, vinyl chloride, vinyl acetate, vinyl benzoate, vinyl methyl ketone, vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; Polymerized styrene resin, epoxy resin, polyester resin,
Polyurethane resins and the like can be mentioned.

As the coloring agent, carbon black,
Examples include aniline blue, calco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, and mixtures thereof. These colorants must be contained in a sufficient ratio to form a visible image having a sufficient concentration, and are contained in an amount of 1 to 2 with respect to 100 parts by weight of the binder resin.
The ratio is about 0 parts by weight. Examples of the charge control agent include a metal-containing complex dye, a nigrosine dye, a quaternary ammonium salt, a triphenylmethane control agent, and a resin control agent.

The non-magnetic one-component developing toner of the present invention can be used in a non-magnetic one-component developing apparatus using a positive or negative photosensitive member. In the case of a positive polarity photoreceptor, there are an organic photoreceptor, an amorphous silicon photoreceptor, a selenium photoreceptor and the like, and an organic photoreceptor and an amorphous silicon photoreceptor which are environmentally friendly such as disposal are preferable. Also,
The developing device has a rubber or metal developing sleeve having a surface that carries and transports the non-magnetic one-component developing toner, and a rubber or metal blade member provided with a surface close to or pressed against the developing sleeve. A developing sleeve for supplying a non-magnetic one-component developing toner to the developing sleeve, applying the applied toner so as to form a thin toner layer by a blade member, applying a charge, and holding an electrostatic latent image. Approach in contact or non-contact state, develop the electrostatic latent image,
Then, transfer to paper is performed. The non-magnetic one-component developing toner of the present invention may be a positive polarity toner or a negative polarity toner by selecting the material of the blade member and the charge control agent constituting the toner. Depending on this polarity, the present invention can be applied to both the forward development method and the reverse development method.

[0020]

The present invention will be described below with reference to examples. (Example 1) 90% by weight of polyester resin 7% by weight of carbon black (trade name: # 40, manufactured by Mitsubishi Chemical Corporation) 1% by weight of metal-containing dye (trade name: Bontron S-3 manufactured by Orient Chemical Industry Co., Ltd.)
4) Low-molecular-weight polypropylene 2% by weight (trade name: Viscol 550P, manufactured by Sanyo Chemical Industry Co., Ltd.) After mixing the raw materials having the above mixing ratios with a super mixer, heat melting at a temperature of 165 ° C using a biaxial kneader. The mixture was kneaded, pulverized by a jet mill, and then classified by a dry air classifier to obtain toner particles having a volume average particle diameter of 9 μm. The polyester resin is a polycondensate of terephthalic acid, isophthalic acid, trimellitic acid, bisphenol A / polyoxyethylene adduct, bisphenol A / polyoxypropylene adduct, and ethylene glycol, and has a weight average molecular weight of 4 .28 × 10 ⁴ , number average molecular weight 0.434 × 10 ⁴ , acid value 6 mgKOH / g. Next, 100 parts by weight of the toner particles and alumina particles having an Al ₂ O ₃ content of 99.7% by weight (volume average particle diameter:
3 μm) 0.3 parts by weight and magnetite particles (spherical,
1 part by weight of an average particle diameter: 0.3 μm) was stirred and mixed with a Henschel mixer for 10 minutes, and then 0.5 part by weight of hydrophobic silica (trade name: TS-530, manufactured by Cabot Corporation) was added, followed by stirring and mixing for 2 minutes. Thus, a non-magnetic one-component developing toner of the present invention was obtained.

Example 2 The same procedure as in Example 1 was repeated except that 0.3 parts by weight of alumina particles having an Al ₂ O ₃ content of 99.9% by weight were used as the alumina particles. A component developing toner was obtained.

Comparative Example 1 A comparative non-magnetic one-component developing toner was obtained in the same manner as in Example 1, except that alumina particles were not used.

COMPARATIVE EXAMPLE 2 A comparative non-magnetic powder was prepared in the same manner as in Example 1, except that 0.3 parts by weight of alumina particles having an Al ₂ O ₃ content of 85.8% by weight were used as the alumina particles. A component developing toner was obtained.

The non-magnetic one-component developing toners obtained in Examples and Comparative Examples were set in a laser printer which is a non-magnetic one-component developing device having a negative organic photoreceptor, and the following characteristics were evaluated. The results are shown in Table 1. (1) Reproducibility of image density, fog and black solid image The image density of a black solid image portion is a reflection density meter RD manufactured by Macbeth.
The fog was measured with a color meter ZE2000 manufactured by Nippon Denshoku Industries Co., Ltd. The solid black reproducibility was evaluated by visually observing the solid black image portion, and those having no unevenness in the image density were evaluated as ○, those having a little unevenness as △, and those having many unevenness as x. These characteristics were evaluated after 10 copies (initial stage) and after continuous printing of 20,000 copies. (2) Toner Consumption and Transfer Efficiency Toner consumption and transfer efficiency were determined by the following formula after printing 20,000 sheets.

[0025]

(Equation 1)

[0026]

(Equation 2)

[0027]

[Table 1]

According to Table 1, the non-magnetic one-component developing toner of the present invention has an image density of 1.40 or more and a fog of 0.
When it was 32 or less, there was no problem in black solid reproducibility, the toner consumption was small, and the transfer efficiency was 87% or more. On the other hand, Comparative Examples 1 and 2 have problems in black solid reproducibility and fog, and toner consumption is also 1%.
30g or more per 000 sheets, transfer efficiency 80%
This is a result having a practical problem of less than the above.

[0029]

The non-magnetic one-component developing toner of the present invention is
When applied to a non-magnetic one-component developing device, image characteristics with little fog, excellent black solid reproducibility, and good transferability can be obtained.

Claims (3)

[Claims] 1. A non-magnetic monocomponent comprising alumina particles having an Al ₂ O ₃ content of 90% by weight or more attached to the surface of toner particles containing at least a binder resin and a colorant. Development toner. 2. The non-magnetic one-component developing toner according to claim 1, wherein the Al ₂ O ₃ content of the alumina particles is 99% by weight or more. 3. The non-magnetic one-component developing toner according to claim 1, wherein the hydrophobic silica particles and the magnetic powder are attached to the surface of the toner particles.