JPH117149A - Electrostatic charge image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner having excellent fluidity, triboelectric property, toner supplying property and cleaning property and therefore, which does not cause decrease or irregular image density or damages on a photoreceptor. SOLUTION: This toner is prepared by mixing at least one external additive and color resin particles containing a binder resin and a coloring agent and is used to develop an electrostatic charge image. At least one external additive consists of hydrophobic alumina which has 1:1 to 1:1.5 ratio of minor diameter to major diameter and is treated with a hydrophobic agent. It is preferable to compound the hydrophobic alumina by 0.01 to 10 pts.wt. to 100 pts.wt. of the color resin particles of the toner.

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 for developing an electrostatic latent image in electrophotography, electrostatic recording, and electrostatic printing.

[0002]

2. Description of the Related Art As a developing method applied to an electrophotographic method or an electrostatic recording method, a two-component developer using a toner and a carrier and applying a charge to the toner by frictional charging between the toner and the carrier is used. Method and method for applying electric charge to toner by frictional charging between toner and toner carrier without using a carrier or frictional charging between blade and toner for regulating the thickness of toner layer contacting toner and toner carrier There is a one-component development method. Either method makes it possible to visualize the electrostatic latent image on the photoreceptor or electrostatic recording medium and obtain a copy. The toner is conveyed by a developer carrier or a toner carrier (so-called sleeve) onto a development area on a photoconductor or an electrostatic recording medium, that is, on an electrostatic latent image, and the toner adheres to the electrostatic latent image to form an electrostatic latent image. Is visualized, and the visualized toner image is transferred and fixed onto a transfer receiving body such as paper to obtain a copy. on the other hand,
The toner remaining on the photoconductor or the electrostatic recording medium without being transferred is cleaned in preparation for the next copying process.

In recent years, the electrophotographic method, the electrostatic recording method, and the electrostatic printing method as described above require increasingly higher image quality, higher definition, and coloration. , Light weight, low power consumption, etc. are required.

In order to meet the demand for higher definition and higher image quality in electrophotography, various fine powders are added to a base toner in order to further improve various image characteristics such as resolution, uniformity of density, and fog. It has been conventionally studied to improve the chargeability and fluidity of the toner by adding the toner.

For example, Japanese Patent Publication No. 53-39307,
JP-A-60-238849, JP-A-64-885
No. 54, JP-A-2-1090589, JP-A-5-19528 and JP-A-6-19186 propose toners containing surface-treated titanium oxide. Since titanium oxide is used, the fluidity is insufficient, so that a satisfactory triboelectric charge amount cannot be obtained, resulting in a decrease in image density and fogging, and an increase in the amount of toner required to form one copy. In the case of a large number (for example, when copying a document having a large solid portion), the stability of the supply of the toner onto the toner carrier and the transportability of the toner to the developing area are not sufficient, so that the image density decreases and the image becomes uneven. Had the problem of causing Further, there has been a problem that the photoreceptor is finely scratched when a large number of copies are made.

Japanese Patent Application Laid-Open No. 4-40467 proposes a method for improving the chargeability and fluidity by adding hydrophobic spherical titanium oxide fine particles to a toner. However, such titanium oxide has fine pores inside the primary particles and has a large specific surface area, so that the density of the hydrophobic group is increased and the triboelectrification is improved. As a result, there is a problem in that toner aggregates and sleeve filming in which the toner electrostatically adheres to the sleeve occurs, resulting in a decrease in image density and unevenness. Further, when the above-described titanium oxide and the base toner are mixed to obtain a toner,
As a result of the improved triboelectricity of the external additive titanium oxide itself, the titanium oxide itself tends to charge up, so that the external additive titanium oxide aggregates, and a predetermined amount of titanium oxide is applied to the surface of the base toner. In order to make the predetermined amount of titanium oxide adhere to the base toner while making it difficult to uniformly adhere to the base toner, a predetermined amount or more of titanium oxide must be used in consideration of the amount of aggregation and non-adhesion to the base toner. However, there is a problem in that the loss of expensive additives is large both economically and in the production process.

Particularly, in the case of a color toner, development and transfer are repeated for each color, and the amount of toner of each color is larger than when only one color toner is used. However, when titanium oxide having a non-round shape and hydrophobic spherical amorphous titanium oxide fine particles having a large specific surface area were used, the results were extremely inadequate.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its main objects the following (1) to (3). (1) To provide a toner for developing an electrostatic charge image capable of providing a stable image without a decrease in image density or unevenness by improving fluidity, triboelectricity, toner supply property, and toner transportability. . (2) To provide a toner for developing an electrostatic image in which aggregation of toner due to charge-up and sleeve filming of the toner hardly occur even when a large number of copies are made. (3) To provide a toner for developing an electrostatic charge image having excellent cleaning properties without damaging the photosensitive drum even after many cleanings.

[0009]

According to a first aspect of the present invention, there is provided a toner for developing an electrostatic charge image comprising a mixture of colored resin particles containing a binder resin and a colorant and at least one external additive. ,
At least one type of external additive has a ratio of the minor axis to the major axis of 1: 1 to 1
A toner for developing an electrostatic image, wherein the toner is a hydrophobized alumina obtained by surface-treating alumina having a ratio of 1: 1.5 with a hydrophobizing agent.

According to a second aspect of the present invention, there is provided a toner for developing an electrostatic image according to the first aspect, wherein 0.01 to 10 parts by weight of hydrophobic alumina is mixed with 100 parts by weight of the colored resin particles. is there.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, hydrophobized alumina obtained by surface-treating alumina with a hydrophobizing agent and having a ratio of minor axis to major axis of 1: 1 to 1: 1.5 is used as an external additive. is important. That is, the ratio of the minor axis to the major axis is 1:
When the ratio exceeds 1.5 and the shape of a stick or rice grain is obtained, the fluidity is remarkably poor, and the photoreceptor is easily damaged. The ratio of the minor axis to the major axis is preferably 1: 1.3.

In the present invention, examples of the hydrophobizing agent used for hydrophobizing alumina include a compound which reacts with a hydroxyl group on the surface of alumina or a compound which physically adsorbs. Specific examples include an organic silicon compound and an organic titanium compound. Compounds, organoaluminum compounds and the like are used, and silane compounds, silicone oils and silicone varnishes are preferably used, and a plurality of types of hydrophobizing agents may be used in combination.

Specific examples of silane compounds include alkoxysilanes, halosilanes, isocyanate silanes, hydrosilanes, alkyl silanes, aryl silanes, vinyl silanes, acrylic silanes, epoxy silanes, silyl compounds, siloxanes , Silyl ureas, silyl acetamides, and silane compounds having different substituents of these silane compounds at the same time.

Examples include alkoxysilanes represented by R _4-X Si (OR ¹ ) _X , wherein X is an integer of 1 to 3, and R ¹ is a methyl group, an ethyl group, a propyl group, or an isopropyl group. Butyl, isobutyl, t-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl and the like.

As R, for example, some or all of the hydrogen atoms may be substituted by fluorine atoms, and aryl groups such as phenyl, tolyl and naphthyl, and aralkyl groups such as benzyl and styryl. , Propenyl, butenyl, allyl, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl Group, nonyl group,
And alkyl groups such as decyl group, other ethynyl groups, vinyl groups and the like. When 4-X is not 1, a plurality of R
When they have the same group, they may be the same group or different groups. Further, in R, a part or all of the hydrogen atoms may be replaced by fluorine atoms. Alumina can be treated uniformly, the degree of hydrophobicity can be increased, and when the treated powder is used as an external additive, the fluidity of the toner is not impaired, and the chargeability, cleaning properties, and durability are excellent. Is preferably an alkyl group having 3 to 4 carbon atoms.

For example, trialkylalkoxysilane,
Dialkyl dialkoxy silane, alkyl trialkoxy silane and the like can be mentioned. Examples of the trialkylalkoxysilane include trialkylmethoxysilane such as trimethylmethoxysilane, triethylmethoxysilane, tripropylmethoxysilane, and tributylmethoxysilane, as well as various trialkylethoxysilanes, trialkylpropoxysilanes, and trialkylbutoxysilanes. No.

As the dialkyl dialkoxysilane,
Dialkyldimethoxysilane, such as dimethyldimethoxysilane, diethyldimethoxysilane, dipropyldimethoxysilane, diisopropyldimethoxysilane, dibutyldimethoxysilane, di-tert-butyldimethoxysilane, and dibutyldimethoxysilane, as well as various dialkyldiethoxysilanes and dialkyldipropoxysilanes And dialkyldibutoxysilane.

As the trialkylalkoxysilane,
In addition to alkyltrimethoxysilane such as methyltriethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isopropyltrimethoxysilane, butyltrimethoxysilane, and isobutyltrimethoxysilane, various alkyltriethoxysilanes and alkyltripropoxysilanes, Alkyl tributoxy silane and the like can be mentioned.

[0019] As the silane compound used in the present invention, halosilanes represented by R _4-X SiA _X can be mentioned. In the formula, X and R are the same as in the case of the alkylalkoxysilane, and A represents halogen. Such halosilanes include trimethylchlorosilane, dimethyldichlorosilane, benzylmethyldichlorosilane, chloromethyldimethylchlorosilane, bromomethyldimethylchlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, methyltrichlorosilane, α
Chlorosilanes such as -chloroethyltrichlorosilane and β-chloroethyltrichlorosilane, as well as various bromosilanes and iodosilanes.

Other examples of the silane compound used in the present invention include isocyanate silane represented by R _4-x Si (NCO) _x , hexamethyldisilazane,
There are triorganosilyl mercaptan, trimethylsilyl mercaptan, hexamethyldisiloxane and the like. In the above formula, X and R are the same as in the case of the above-mentioned alkylalkoxysilane.

The silicone oil used in the present invention includes, for example, reactive silicones such as epoxy-modified, carboxyl-modified, carbinol-modified, phenol-modified, methacryl-modified, mercapto-modified and heterofunctional-group-modified.
Non-reactive silicones such as polyether-modified, methylstyryl-modified, alkyl-modified, fatty acid-modified, alkoxy-modified, and fluorine-modified; straight silicones such as dimethyl silicone, methylphenyl silicone, diphenyl silicone, and methyl hydrogen silicone.

Among these silicone oils, non-reactive silicones and straight silicones are preferably used. Specific examples include dimethyl silicone and polyether-modified silicone. By using these silicone oils, lubricity is enhanced and cleaning properties are improved, and the degree of hydrophobicity is increased and humidity resistance is improved.

In the present invention, the ratio of the minor axis to the major axis is 1:
Alumina of 1-1: 1.5 (hereinafter abbreviated as spherical alumina)
Preferably, 100 parts by weight are treated with 1 to 40 parts by weight of a hydrophobizing agent, more preferably with 2 to 30 parts by weight. If the amount is less than 1 part by weight, the environmental resistance becomes insufficient, and
If the amount is more than 10 parts by weight, the hydrophobized spherical alumina tends to agglomerate and the fluidity tends to deteriorate.

When the hydrophobizing agent is a silane compound, the amount is preferably 1 to 30 parts by weight, more preferably 5 to 25 parts by weight, based on 100 parts by weight of spherical alumina.
If the amount is less than 1 part by weight, hydrophobization is insufficient, so that satisfactory environmental resistance and triboelectricity cannot be obtained. On the other hand, when the amount exceeds 30 parts by weight, the hydrophobic treatment becomes non-uniform, and on the contrary, the degree of hydrophobicity becomes smaller than when the treatment amount is small, and the environmental resistance is lowered. Minutes adhere and cause agglomeration, resulting in poor fluidity.

When the hydrophobizing agent is a silicone oil compound, the amount is preferably 2 to 40 parts by weight, more preferably 5 to 30 parts by weight, per 100 parts by weight of spherical alumina. If the amount is less than 2 parts by weight, satisfactory hydrophobicity cannot be obtained due to insufficient hydrophobicity. On the other hand, when the amount exceeds 40 parts by weight, the hydrophobizing treatment becomes non-uniform, and aggregation is easily caused.

It is also possible to use a silane compound and a silicone oil in combination as a hydrophobizing agent. In such a case, the combined treatment amount is preferably 3 to 40 parts by weight, particularly preferably 5 to 40 parts by weight. 30 parts by weight. As described above, the hydrophobization treatment becomes non-uniform, and aggregation is easily caused.

When a silane compound and a silicone oil are used in combination as a hydrophobizing agent, it is preferable that spherical alumina is first treated with a silane compound and then treated with silicone oil. That is, if the silicone oil is adsorbed on the spherical alumina surface and covers the surface, the coupling reaction between the silane compound and the hydroxyl group on the surface of the (base) of the spherical alumina is impaired. After the coupling reaction with the silane compound, the unreacted hydroxyl groups on the surface of the base material are allowed to adsorb the silicone oil, whereby the degree of hydrophobicity can be further improved, and the environmental resistance stability can be improved.

The degree of hydrophobicity in the present invention is determined by methanol titration as follows. Float 0.2 g of the sample in 50 cc of ion-exchanged water in a beaker, and titrate the methanol with a burette while stirring. The point where the sample floating on the liquid surface completely disappears is determined as the end point. Ask for degrees. Hydrophobicity (%) = [titration (cc) / (titration (cc) +50 (c
c))) × 100 The hydrophobicity of the hydrophobized alumina used in the present invention is 30 to
It is preferably 95%, more preferably 40 to 85%, particularly preferably 50 to 75%. If it is less than 30%, the hydrophobicity is insufficient and the moisture resistance becomes poor, and the developability under high humidity and the stability over time are liable to deteriorate. On the other hand, if it exceeds 95%, aggregation of the fine particles is liable to occur, and it is difficult to uniformly disperse the particles on the surface of the colored resin particles (base toner), and it is difficult to obtain a desired effect.

In the present invention, the colored resin particles (base toner) contain a binder resin and a colorant.
As the binder resin, a resin exemplified below can be used. For example, polystyrene, a homopolymer of styrene such as polyvinyl toluene and a substituted product thereof; styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-butadiene copolymer,
Styrene-based copolymers such as styrene-isoprene copolymer, phenolic resin, acrylic resin, methacrylic resin,
Silicone resin, epoxy resin, polyester resin, polyol resin and petroleum resin can be used. Preferred binder resins include styrene-based copolymers, polyester resins, and epoxy resins, and particularly include epoxy resins, polyester resins, polyol resins, and graft copolymers thereof.

Examples of comonomers for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, and the like. Monocarboxylic acid having a double bond such as butyl methacrylate or a substituted product thereof, vinyl esters, ethylene-based olefins,
Vinyl monomers such as vinyl ketones are used alone or in combination of two or more.

The styrenic polymer or styrenic copolymer may be cross-linked, or may be a mixed resin. Examples of the crosslinking agent for the styrene-based polymer or the styrene-based copolymer include divinylbenzene, divinylnaphthalene, and ethylene glycol diacrylate.

Polyester resins, epoxy resins, polyol resins and the like are binder resins which are preferably used because of their excellent fixability, especially in full-color toners.
There is a problem that the charging property is easily affected by environmental changes. However, since the hydrophobized spherical alumina as described above has a good chargeability balance, by using it for a colored resin particle (base toner) using such a binder resin, a favorable triboelectric chargeability and high fluidity can be achieved. Even if the environment changes, a stable image can be obtained due to its excellent developability and transferability, and a beautiful image having further excellent cleaning properties can be obtained.

As the polyester, for example, a bisphenol derivative represented by a bisphenol A-alkylene oxide adduct such as bisphenol A-ethylene oxide adduct or bisphenol A-propylene oxide adduct as a diol component, or a substituted product thereof is used alone. Or the above bisphenol derivative in combination with an aliphatic dialcohol such as ethylene glycol, diethylene glycol, etc.
Or higher carboxylic acids (eg, fumaric acid, maleic acid, phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, etc.), and its acid anhydrides (eg, maleic anhydride, phthalic anhydride, etc.), or Polyester resins obtained by condensing or co-condensing with a carboxylic acid component such as a lower alkyl ester are mentioned, and those having sharp melting characteristics are preferable.

The coloring agents for obtaining the colored resin particles used in the present invention include aniline blue, calcoyl blue, chrome yellow, ultramarine blue, methylene blue chloride, phthalocyanine blue, malachite green oxalate, rhodamine lake, and lake red. , Permanent red, quinacridone, chrome yellow, quinoline yellow, permanent yellow, hansa yellow, benzidine yellow, lamp black,
Rose bengal, carbon black and the like can be exemplified as typical ones. The colorant as described above is preferably used in an amount of 1 to 12 parts by weight, more preferably 1.5 to 10 parts by weight, based on 100 parts by weight of the binder resin.

When a chromatic organic pigment is used as the colorant, the toner of the present invention can be used as a non-magnetic one-component color toner in a non-magnetic one-component printer or fax machine. As a non-magnetic two-component color toner used by mixing with a carrier, the non-magnetic two-component development type digital or analog copying machine can be suitably used.

When an achromatic pigment represented by carbon is used as the colorant, the toner of the present invention is
It can also be used in printers and faxes as a non-magnetic one-component black toner. Further, when used in a mixture with a carrier, it can be suitably used as a non-magnetic two-component black toner in the above-mentioned various copying machines.

If a colorant having magnetism is used, it can play a role as a magnetic material and can be used as a magnetic toner. Examples of such magnetic coloring agents include iron oxides of magnetite, hematite, and ferrite;
Metals such as iron, cobalt and nickel or alloys of these metals such as aluminum, copper, zinc and manganese, and mixtures thereof are used. As the shape of the magnetic powder, polyhedrons such as hexahedron, octahedron, decahedron, dodecahedron, and tetrahedron, needles, scales, spheres, and irregular shapes can be used. The content of the magnetic powder is 10 to 200 parts by weight, preferably 20 to 170 parts by weight, based on 100 parts by weight of the binder resin.
Particularly preferred is 30 to 150 parts by weight.

When the above-described colorant having magnetism is used, the toner of the present invention can be used as a magnetic one-component toner in a copier, a printer or a facsimile machine of a magnetic one-component developing system. Can be used as a magnetic two-component toner in various magnetic two-component developing system copying machines.

The coloring resin particles (base toner) used in the present invention may contain the following waxes to improve the releasability from the fixing member at the time of fixing and to improve the fixing property to the material to be transferred. It is preferably contained in the toner. For example,
Paraffin wax and its derivatives, montan wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, carbana wax and its derivatives.

Further, the colored resin particles (base toner) used in the present invention may contain a charge control agent. The charge amount can be controlled by controlling the type and amount of the compound to be added for each constituent material of the colored resin particles (base toner). Those which positively charge the colored resin particles (base toner) include, for example, modified products such as nigrosine and fatty acid metal salts, quaternary ammonium salts such as tetrabutylammonium tetrafluoroborate, triphenylmethane dyes and lake pigments thereof. There is. Azo-metal complexes, polymeric quaternary ammonium salts, salicylic acid derivative metal complexes, and the like can be used to negatively charge the colored resin particles (base toner). It is preferable to blend a colorless or light-colored charge control agent for the color toner. Note that the binder resin, the colorant, the charge control agent, and the like are not limited to those described above.

The colored resin particles (base toner) used in the present invention are kneaded using a kneader such as a hot roll kneader or an extruder after sufficiently mixing the above-mentioned various materials with a Henschel mixer or other mixer. A method of mechanically pulverizing and classifying the kneaded material after cooling and individualizing the kneaded material is preferable. Alternatively, a toner manufacturing method by a polymerization method in which a predetermined colorant or the like is mixed with a monomer to constitute a binder resin to form an emulsion suspension and then polymerized to obtain a toner may be used.

As the colored resin particles (base toner) used in the present invention, it is preferable to use a toner having a small particle size for high definition and high image quality.
It is more preferably 2 μm, more preferably 6 to 10 μm.

The toner of the present invention can be obtained by sufficiently mixing a specific hydrophobized spherical alumina and colored resin particles (base toner) with a mixer such as a Henschel mixer.

The toner of the present invention is obtained by adding various external additives to colored resin particles (base toner) in order to improve developability and durability, in addition to the specific hydrophobized spherical alumina. There may be. For example, metal oxides such as magnesium, zinc, titanium, cerium, iron, cobalt, zirconium, manganese, strontium, tin, antimony; composite metal oxides such as calcium titanate, strontium titanate, magnesium titanate; kaolin such as kaolin Clay minerals; phosphorus oxides such as apatite; silica;
Silicon compounds such as silicon nitride and silicon carbide are exemplified. Among them, aluminum oxide, calcium titanate and magnesium titanate are preferred. Further, the above external additives can be used in combination.

For the same purpose, the following organic particles or composite particles can be added. For example, polyamide resin particles,
Resin particles such as silicone resin particles and acrylic resin particles; and composite particles composed of rubber, wax, and fatty acid compound resin and inorganic particles such as metal, metal oxide, salt, and carbon black.

Further, lubricant powders can be added, for example, fluorine compounds such as Teflon and polyvinylidene fluoride; metal salts of fatty acids such as zinc stearate; fatty acid derivatives such as fatty acids and fatty acid esters; molybdenum sulfide, amino acids and amino acid derivatives Is mentioned.

When the two-component developer is prepared by mixing the toner of the present invention with a carrier, the toner is used in an amount of 1 to 15% by weight.
A suitable result is obtained with a concentration of. The carrier that can be used in combination with the toner of the present invention has an average particle diameter of 30 to 250 μm, particularly preferably 40 to 120 μm.
m, a magnetic powder of iron, nickel, cobalt, iron oxide, ferrite, or the like, that is, a so-called non-coated carrier, or a magnetic material such as a core material, and a surface of which is coated with an insulating resin, for example, a styrene resin or an acrylic resin. So-called coating carrier coated with resin, silicone resin, fluorine resin or the like, or having an average particle size of 3 to 20 μm
A so-called magnetic powder-dispersed resin carrier obtained by dispersing about 60 to 95% by weight of a magnetic powder of about m in styrene-acrylic resin, polyester resin or the like is included.

Examples of the coating resin for the coating carrier include a silicone resin, a fluorine resin and an acrylic resin. Silicone resins include, for example, straight silicone varnish and modified silicone varnish,
It is preferable to use an organopolysiloxane having a weight-average molecular weight of about 10 ³ to 10 ⁶ as a main agent and coat the core material with a polymer containing an organopolysiloxane having a three-dimensional network structure having a siloxane bond as a main chain. If a coating carrier coated with such a resin is used, the chargeability of the toner is stabilized, and high image quality and high image density can be maintained for a long time.

Examples of the acrylic resin include, for example, methyl methacrylate-styrene copolymer, methyl methacrylate-styrene-2-ethylhexyl acrylate copolymer, methyl methacrylate-methyl acrylate copolymer, and methyl methacrylate-n-butyl acrylate copolymer. Examples of the combination include, but are not limited to, these.

Such a coating carrier can be produced by various known methods. For example, after dissolving the above-described silicone resin in an organic solvent, applying the solution onto a core agent by a dipping method, a spraying method or a fluidized bed method, and drying. , 100-250
The coating can be cured by heating at ℃.

The toner of the present invention can develop an electrostatic latent image formed on a photosensitive member or an electrostatic recording member. That is, selenium, zinc oxide, cadmium sulfide, an inorganic photoconductive material such as amorphous silicon, phthalocyanine pigment, an electrophotographic electrostatic latent image formed on a photoreceptor made of an organic photoconductive material such as bisazo face, or An electrostatic latent image is formed on an electrostatic recording medium having a dielectric material such as polyethylene terephthalate using a needle electrode or the like, and the electrostatic latent image is formed on the electrostatic latent image by a developing method such as a magnetic brush method, a cascade method, or a touch-down method. A toner image is formed by the developer of the present invention. The toner image is transferred to a transfer material such as paper and then fixed to form a copy, and the toner remaining on the surface of the photoreceptor or the like is cleaned. Cleaning methods include blade method, brush method,
Various methods such as a web method and a roll method can be used.

[0052]

EXAMPLES In the following production examples, examples and comparative examples,
% Means weight%, and parts means part by weight.

[0053]

[External additive production example 1] Hydrophobized alumina a1 (a1 fine particles) 10 g of base material a (manufactured by CI Kasei Co., Ltd .: alumina having a gamma-type crystal of 95% or more in spherical primary particles, particle size of 32 nm) is isobutyltrimethoxysilane 2.0 g was dissolved in a 95% aqueous solution of methanol and dispersed with a homogenizer.
It was reacted with hydroxyl groups on the surface of the substrate. After filtration, washing and drying, the mixture was pulverized in a mortar to obtain hydrophobic alumina a1 fine particles.

[0054]

[External additive production example 2] Hydrophobized alumina a2 (a2 fine particles) Substrate a (produced by C-I Kasei Co., Ltd .: alumina having a gamma-type crystal of 95% or more in spherical primary particles, particle size 32 nm) was treated with 10 g of C
The solution was placed in an ethyl acetate solution in which 2.0 g of H ₃ Si (NCO) ₃ was dissolved, dispersed with a homogenizer, and reacted on the surface of the substrate. After filtration, washing and drying, the mixture was pulverized in a mortar to obtain hydrophobic alumina a2 fine particles.

[0055]

[External additive production example 3] Hydrophobized alumina a3 (a3 fine particles) Substrate a (manufactured by C-I Kasei Co., Ltd .: alumina having a gamma-type crystal of 95% or more in spherical primary particles, particle size 30 nm) is 10 g
The solution was placed in a 95% aqueous solution of methanol in which 1.5 g of -propylethoxysilane was dissolved, and stirred with a homogenizer to react with hydroxyl groups on the surface of the substrate. Further, 1.0 g of dimethyl silicone was added and stirred, and allowed to adhere to the surface of the substrate.
Then, after filtration, washing and drying, the mixture was pulverized in a mortar to obtain hydrophobic alumina a3 fine particles.

[0056]

[External additive production example 4] Hydrophobized titanium oxide b1 (b1 fine particles) 10 g of base material b (manufactured by Nippon Aerosil Co., Ltd .: trade name P-25, anatase type crystal whose primary particles are rice granules, particle size 30 nm)
Was placed in a 95% aqueous solution of methanol in which 2.0 g of isobutyltrimethoxysilane was dissolved, dispersed with a homogenizer, and reacted with hydroxyl groups on the substrate surface. After filtration, washing and drying, the mixture was pulverized in a mortar to obtain hydrophobic titanium oxide b1 fine particles.

[0057]

[External additive production example 5] Hydrophobized titanium oxide c1 (c1 fine particles) Substrate c (manufactured by Teica Co., Ltd .: trade name: MT-150A, alumina of rutile type crystal whose primary particles are rice grains, particle size: 20 nm) 1
0 g was placed in a 95% aqueous solution of methanol in which 2.0 g of isobutyltrimethoxysilane was dissolved, dispersed with a homogenizer, and reacted with hydroxyl groups on the surface of the substrate. Filtration, washing,
After drying, the mixture was pulverized in a mortar to obtain hydrophobic titanium oxide c1 fine particles.

[0058]

[External additive production example 6] Hydrophobized titanium oxide d1 (d1 fine particles) Substrate d (manufactured by Idemitsu Kosan Co., Ltd .: trade name IT-S, amorphous titanium oxide in which primary particles are in the form of porous balls, particle diameter 20 n)
m) Put 10 g in a reaction vessel,
C. and heated to n-propyltriethoxysilane.
0 g was heated and vaporized or atomized at 200 ° C. and introduced into the reaction vessel. The above operation was performed under a nitrogen stream, and the solution was collected with a filter to obtain hydrophobic titanium oxide d1 fine particles.

The physical properties of the substrates a to d and the physical properties of the hydrophobized aluminas a1 to a3, b1, c1, and d1 are shown in Table 1.
And 2.

[0060]

Example 1 100 parts of a polyester resin obtained by co-condensing propoxylated bisphenol with terephthalic acid and trimellitic acid 2.5 parts of a coloring agent (phthalocyanine pigment) was premixed with a Henschel mixer and melt-kneaded with an extruder. After cooling, crushed with a hammer mill,
Next, the mixture was finely pulverized by an air jet mill and classified to obtain toner particles having a volume average particle diameter of 8 μm.

The obtained toner particles (base toner particles) 1
Hydrophobized alumina a obtained in Production Example 1 as an external additive in 00 parts
0.8 parts of one fine particle was mixed with a Henschel mixer, and further subjected to a 150-mesh (plain weave) sieving process for the purpose of removing coarse particles to obtain a toner A1 (cyan toner) for electrostatic image development.

Next, a methyl methacrylate-styrene copolymer (45:55) having a weight average molecular weight of 70,000 and a glass transition temperature of 59 ° C. was diluted in a toluene solvent, and the obtained acrylic resin solution was mixed with copper-zinc-ferrite. The carrier core material is heated and stirred at 170 ° C. by an immersion method, and the solvent toluene is removed. The coated amount of the resin is 0.25% by weight based on the carrier weight, and the acrylic resin-coated carrier has an average particle size of 50 μm. I got A1 cyan toner 5
And 95 parts of the carrier were mixed to obtain a color developer.

Using this color developer, a continuous digital color electrophotographic copying machine was used to produce 100 continuous images at 23 ° C./50% RH using all solid image originals. Thus, an image excellent in cleaning properties without soiling was obtained. In addition, no toner was scattered in the machine. Next, when a 10,000-sheet image was produced instead of a 5% image area original, a high image with an average development / transfer efficiency of 83%, an image density of 1.60, no fog was obtained, and the toner consumption was low. The average was as small as 39 g per 1K. When the same image was formed under high temperature and high humidity (30 ° C./85% RH), the average development / transfer efficiency was 8%.
A high image density of 1%, a good image density of 1.61 and no fog were obtained, and the toner consumption was as small as 40 g per 1K on average. Further, when the same image was formed at a low temperature and a low humidity (10 ° C./20% RH), no filming due to toner charge-up occurred, the development / transfer efficiency was as high as 82% on average, and the image density was 1.57. Thus, a stable and good image without a decrease in density was obtained, and the toner consumption was as small as 38 g on average per 1 K. In addition, a multiple copy test (1
After (10,000 sheets), adhesion of toner filming and fusion of the developing sleeve were not confirmed.

Further, even if the toner is left in the toner replenishing box under high temperature and high humidity, and continuous copying is performed after one week, the toner does not absorb the moisture and cause cakeing (soft agglomeration), and the toner conveyance failure does not occur. A stable image without unevenness was obtained.

The development / transfer efficiency is ((toner consumption-recovered toner amount) / toner consumption) × 100%, and indicates the ratio of toner effectively consumed for image formation. A developer with low toner consumption, high development / transfer efficiency and high image density has a long life and is desirable.

[0066]

Example 2 a2 obtained in Production Example 2 instead of a1 fine particles
A toner A2 for developing an electrostatic image was prepared in the same manner as in Example 1 except that 0.8 parts of the fine particles were used. When an image was formed in the same manner as in Example 1 using the toner a2, the charge amount was stable without charging up under low temperature and low humidity, and the image density was 1.55. was gotten.

[0067]

Example 3 a3 obtained in Production Example 3 in place of a1 fine particles
A toner A3 for developing an electrostatic image was prepared in the same manner as in Example 1 except that 0.8 parts of the fine particles were used. When an image was formed in the same manner as in Example 1 using the toner A3, even when 100 continuous images were formed using a solid image original in the same manner as in Example 1, the toner supply property was improved without uneven image density. Excellent and good cleaning properties.

[0068]

Example 4 An external additive was prepared in the same manner as in Example 1, except that 0.6 parts of the a1 fine particles used in Example 1 and 0.1 part of silica fine powder R972 (manufactured by Nippon Aerosil Co., Ltd.) were used. Was carried out in the same manner as in Example 1,
The transfer efficiency was stable at 80% or more, and an image was obtained with no unevenness in image density and good cleaning properties.

[0069]

Example 5 The toner for developing an electrostatic image (cyan toner) obtained in Example 4 was used as a developer in a commercially available non-magnetic one-component developing system printer, and 100 continuous solid images were evaluated. As a result, there was no unevenness in image density, the toner supply property was excellent, and the cleaning property was also good. Furthermore,
Good images were obtained even after 3,000 images were printed.

[0070]

Comparative Example 1 b1 obtained in Production Example 4 instead of a1 fine particles
A toner B for electrostatic image development was prepared in the same manner as in Example 1 except that 0.8 parts of the fine particles were used. When 100 continuous images were printed using a full solid image original in the same manner as in Example 1 using toner B, unevenness in image density occurred due to poor fluidity of the toner, and toner supply properties and cleaning properties were poor. It was not enough. In addition, fog occurred in each environment due to insufficient charge amount.

[0071]

Comparative Example 2 c1 obtained in Production Example 5 instead of a1 fine particles
A toner C for electrostatic image development was prepared in the same manner as in Example 1 except that 0.8 parts of the fine particles were used. When an image was formed using toner B in the same manner as in Example 1, continuous 100 images were formed using an all solid image original in the same manner as in Example 1. The cleaning properties and cleaning properties were also insufficient. Further, fog occurred in each environment due to insufficient charge amount. Further, when a large number of copies were made, fine scratches occurred on the photoreceptor, and black streaks appeared in the image.

[0072]

Comparative Example 3 d1 obtained in Production Example 6 instead of a1 fine particles
A toner D for developing an electrostatic image was prepared in the same manner as in Example 1 except that 0.8 parts of the fine particles were used. At this time, about 20% of the added amount of D fine particles remained in the toner sieving process, resulting in loss.
Therefore, the loss was further added and mixed so that the addition amount was substantially 0.8 parts. When a 10,000-sheet image was formed using a 5% original image area using toner D in the same manner as in Example 1, carrier jump occurred due to charge-up under low temperature and low humidity, and carrier adhered to the image, resulting in image defects. It became. Further, the magnetic restraining force of the carrier is weakened by the sleeve filming, and the carrier is spilled. Further, the film is formed on the cleaning blade, and the cleaning property is insufficient.

[0073]

COMPARATIVE EXAMPLE 4 The procedure of Example 4 was repeated except that 0.6 parts of silica fine powder was used without using a1 fine particles as an external additive. 21 and an image defect due to carrier jump was confirmed.

[0074]

COMPARATIVE EXAMPLE 5 The same evaluation as in Example 5 was performed using a printer using the electrostatic charge image developing toners B to D obtained in Comparative Examples 1, 2, and 3 as in Example 5. When all solid images were continuously photographed, image density unevenness occurred, so that not only could toner supply be delayed, but also toner scattering due to an insufficient charge amount occurred, further causing cleaning failure. The toner D causes sleeve filming, especially when 3,000 sheets are actually photographed under a low temperature and a low humidity, and the charged toner adheres strongly to the sleeve. Initial image density 1.50
To 1.24.

[0075]

[Table 1]

[0076]

[Table 2]

[0077]

As described above, the toner for developing an electrostatic image of the present invention can have high fluidity and a suitable charge amount by using spherical alumina as an external additive after hydrophobic treatment. As a result, there is no unevenness in image density, the toner supply property, the transport property, and the cleaning property are good, and the developing / transfer efficiency is stable even in each environment, and the toner consumption can be optimized. A stable image without fog can be obtained at a high image density for a long time.

Claims (2)

[Claims] 1. An electrostatic image developing toner comprising a mixture of colored resin particles containing a binder resin and a colorant and at least one external additive, wherein at least one external additive is A toner for developing an electrostatic image, wherein the toner is a hydrophobized alumina obtained by surface-treating alumina fine particles having a ratio of a major axis to a minor axis of 1: 1 to 1: 1.5 with a hydrophobizing agent. 2. The toner according to claim 1, wherein 0.01 to 10 parts by weight of the hydrophobic alumina is mixed with 100 parts by weight of the colored resin particles.