JP3344211B2 - Electrostatic latent image developer and image forming method - 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 latent image developer used for developing an electrostatic latent image formed by an electrophotographic method, an electrostatic recording method or the like, and an image forming method using the same. .

[0002]

2. Description of the Related Art Conventionally, as an electrostatic latent image developer for visualizing an electrostatic latent image formed on an electrostatic latent image carrying roll, polystyrene, styrene-butadiene copolymer, polyester and the like have been used. A binder resin and a one-component developer composed of a toner obtained by melt-kneading a pigment or a dye such as carbon black or phthalocyanine blue and then pulverizing the toner, or having an average particle diameter substantially the same as that of the toner. A two-component developer in which a toner is mixed with a carrier composed of particles of glass beads, iron, nickel, ferrite or the like having a size of up to 500 μm or a carrier obtained by coating these with various resins is generally used. In particular, two-component developers
Carriers share functions such as agitating, transporting, and charging the developer, and are separated in function as a developer. Therefore, they are widely used at present because of good controllability and the like. In particular, a developer using a resin-coated carrier is excellent in charge controllability, and it is relatively easy to improve environmental dependency and stability over time.

Further, as a developing method, a cascade method or the like has been used in the past, but a magnetic brush method using a magnetic roll as a developer carrier is now mainstream.

[0004] The magnetic brush method using a two-component developer includes:
There are problems such as a reduction in image density due to deterioration of the charge of the developer, generation of remarkable background stains, roughening of the image due to the adhesion of the carrier to the image, consumption of the carrier, and occurrence of uneven image density.

The deterioration of the charge of the developer is apt to occur due to the adhesion (spent) of the toner component to the resin coating layer of the carrier or the peeling of the resin coating layer. At the time of environmental changes such as humidity, at the time of toner addition, and at the time of high toner density, there is a tendency for background stains to occur.

[0006] In order to prevent such charge deterioration, the hardness of the coating resin is increased to make it difficult to peel off, or the surface energy of the coating resin is lowered to prevent the toner component from sticking to the resin coating layer of the carrier. Efforts have been made to combine methods. For example, JP-A-54-92244 proposes a negatively chargeable carrier using polyacrylonitrile and an acrylonitrile copolymer for the purpose of charging stability and preventing carrier deterioration. A combination of a negatively chargeable carrier and an epoxy-based positively charged toner is described. This Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 92244/92 discloses an AB in which acrylonitrile as a monomer is polymerized while being coated on the surface of a core material, or an acrylonitrile is copolymerized with styrene and butadiene.
A method of dissolving S resin in chloroform and coating the core material is adopted. However, with these methods, it is difficult to form a uniform and stable resin coating layer, and a long-life carrier cannot be obtained.

On the other hand, JP-A-61-80161, JP-A-61-80162 and JP-A-61-80163 disclose copolymers of a nitrogen-containing fluorinated alkyl (meth) acrylate and a vinyl monomer, It describes that a resin-coated carrier having a relatively long life is obtained by coating a carrier core material surface with a copolymer of a fluorinated alkyl (meth) acrylate and a nitrogen-containing vinyl monomer.
Further, a polyamide resin is disclosed in JP-A-1-118150, and a melamine resin is coated on the surface of a carrier core material in JP-A-2-79862, and further cured to obtain a resin-coated carrier having a relatively hard coating. Is described. However, these carriers cannot sufficiently prevent toner components from adhering to the carrier surface, and are not satisfactory.

In order to prevent such spent,
It is preferable to use a silicone resin as described in JP-A-60-186844 and a fluorine-based resin as described in JP-A-64-13560. However, even if these resins are used at the same time as the above-mentioned polymer or resin to coat the carrier core material surface, since there are many silicone resins and fluorine-based resins having a lower specific gravity in the upper layer of the resin coating layer, long-term use is not possible. Due to the wear of the resin coating layer from the carrier surface, the silicone resin and the fluorine-based resin are eventually lost. For this reason, even if the carrier described in the above-mentioned publication is used, spent cannot be sufficiently prevented continuously.

[0009]

On the other hand, additives are often externally added to the toner in order to prevent the toner from sticking to the surface of the carrier particles and extend the life of the developer. Examples of the additives include hydrophobic silica fine powder (Japanese Patent Application Laid-Open No. 52-30437), silica fine particles to which aluminum oxide or titanium oxide fine particles are added (Japanese Patent Application Laid-Open No. 60-238847), and vapor-phase titanium oxide. (JP-A-59-52255), anatase-type titanium oxide (JP-A-60-112052), and titanium oxide coated with aluminum oxide (JP-A-57-52255).
-79961) and the like. Further, titanium oxide fine particles that have been surface-treated with a coupling agent (JP-A-4-40607, JP-A-3-13704)
No. 8) and the like, surface treatment of an inorganic compound used as an external additive has also been proposed.

[0010] However, sufficient properties cannot be obtained only by externally adding the external additive alone. For example, the use of hydrophobic fine powder of silica, which is often used at present, significantly improves storage stability, transportability, developability, transferability, and the like. This causes a problem that the chargeability is adversely affected and the charge amount is increased by repeated copying. That is, with respect to the chargeability, the developer is required to satisfy the requirements such as the charge amount, the charge speed, the charge amount distribution, the toner admixability, and the environmental stability of the charge. This has an adverse effect on charging speed, distribution of charging amount, toner admixability, and environmental stability of charging.

When rutile-type or anatase-type titanium oxide is used as an external additive, it is hardly charged if it is not treated. Therefore, coating treatment with alumina or the like, hydrophobic treatment with various coupling agents, etc. are performed. Must be used. However, those treated with alumina are not always effective in preventing the aggregation of titanium oxide particles, and have poor dispersibility when added to toner. Further, those subjected to a hydrophobic treatment with a coupling agent are effective to some extent in improving the chargeability. However, if added alone, the initial charge amount becomes too low and the toner is scattered. Not yet enough.

In order to make use of the advantage of having both properties of the hydrophobic silica and the hydrophobic titanium oxide, a developer containing both of them in a predetermined weight ratio (1: 5 to 1: 1) (Japanese Patent Publication No. 2-27664). However, the contribution of the increase in the amount of charge by the hydrophobic silica is large, and is not satisfactory.

The present invention has been made in view of the above problems in the prior art, and has as its object
It is an object of the present invention to provide a developer for reducing a change in charging characteristics due to a change in humidity, improving its maintainability by combining with an electrostatic latent image developing carrier having a very long life, and obtaining high image quality. .

[0014]

Means for Solving the Problems The present inventors have intensively studied and studied an electrostatic latent image developer and an image forming method in order to improve the above-mentioned drawbacks in the prior art. By adopting the above, the above problem was successfully solved. (1) In an electrostatic latent image developer comprising a toner containing a binder resin and a colorant, and a carrier having a core material and a resin coating layer covering the core material, the toner has a weight of 100% by weight of the toner. Parts by weight of 0.05 to 2.0 parts by weight of hydrophobic silica surface-treated with silicone oil and 0.05 to 2.0 parts by weight of surface-treated titanium dioxide. Is 1: 5.
The resin coating layer is a resin coating layer in which thermosetting resin fine particles are dispersed and contained in a matrix resin, and the thermosetting resin fine particles contain nitrogen atoms and have a critical surface tension of 40. An electrostatic latent image developer comprising a resin of about 70 dyne / cm and the thermosetting resin fine particles having an average particle diameter of 0.1 to 2 μm. (2) In an image forming method for developing an electrostatic latent image on an electrostatic latent image carrier using a developer layer on the developer carrier,
The developer layer is composed of a carrier and a toner, and the toner contains 0.05 to 2.0 parts by weight of hydrophobic silica surface-treated with silicone oil and 100 parts by weight of the toner based on 100 parts by weight of the toner. 0.05 to 2.0 parts by weight are added, the weight ratio of the silica to the titanium dioxide is 1: 5.5 to 1:20, and the carrier is a core material and a resin coating the core material. A thermosetting resin fine particle is dispersed and contained in the resin coating layer, and the thermosetting resin fine particle contains a nitrogen atom and has a critical surface tension of 40 to 70.
An image forming method comprising a dyne / cm resin, and wherein the thermosetting resin fine particles have an average particle size of 0.1 to 2 μm.

By adopting the above-described structure, the present inventors increase the charging potential of the toner itself, improve the charge retention and environmental stability, and provide a good charge-giving ability to the toner during continuous use for a long time. And succeeded in providing an electrostatic latent image developer and an image forming method which maintain the image quality.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The electrostatic latent image developer of the present invention contains a toner and a carrier. The toner contains a binder resin and a colorant, and the colorant is dispersed in the binder resin.

Examples of the binder resin used in the toner include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene and isobutylene; vinyl acetate, vinyl propionate, vinyl benzoate and butyric acid. Vinyl esters such as vinyl; α- such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and dodecyl methacrylate; Esters of methylene aliphatic monocarboxylic acid; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; mono-esters such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone Can be exemplified homopolymers or copolymers of over, particularly typical binder resin, polystyrene, styrene - alkyl acrylate copolymer,
Styrene-alkyl methacrylate copolymer, styrene-
Examples include acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, and polypropylene. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin and the like can also be used.

As the binder resin used for the toner, a polyester resin is particularly preferable. This polyester resin
It comprises a polyhydric hydroxy compound and a polycarboxylic acid or a reactive acid derivative thereof such as a lower alkyl ester, an acid anhydride and an acid halide.

As the colorant used in the toner, any known colorant can be used. For example, carbon black, 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, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Yellow 12, C.I.
I. Pigment Yellow 17, C.I. I. Pigment
Yellow 97, C.I. I. Pigment Blue 15: 1,
C. I. Pigment Blue 15: 3 and the like.

The content of the coloring agent is preferably in the range of 1 to 20 parts by weight based on 100 parts by weight of the binder resin. When the content of the colorant is less than 1 part by weight, the coloring power is weakened, and when the content is more than 20 parts by weight, the fixability of the toner is deteriorated.

In the present invention, for the purpose of charge control, electric resistance control, and the like, the toner may contain various substances such as a fluorosurfactant, salicylic acid, and chromium complex, in addition to the binder resin and the colorant. It may contain a chromium dye, maleic acid, a charge control resin such as a copolymer containing a vinyl monomer having an amino group as a monomer component, a quaternary ammonium salt, and an azine dye such as nigrosine.

Further, the toner may contain a release agent for more complete offset resistance. Examples of the release agent include polyolefins represented by low-molecular-weight polyethylene and low-molecular-weight polypropylene, and the like. Paraffin wax, candelilla wax, carnauba wax,
Natural waxes such as montan wax and derivatives thereof can be used.

The average particle size of the toner is preferably 5 to 12 μm, since the smaller the particle size, the higher the image quality.
More preferably, it is 10 to 10 μm.

In order to improve fluidity, cohesion and environmental stability, silica which has been surface-treated with silicone oil is added to the toner.

Representative examples of the silicone oil include dimethyl silicone oil, methylphenyl silicone oil, and alkyl-modified silicone oil substituted with an ethyl group or a propyl group.

The amount of silicone oil to be treated is 10% silica.
It is preferably from 1.0 to 50.0 parts by weight, more preferably from 5.0 to 40.0 parts by weight, based on 0 parts by weight. The silica preferably has a particle size of 16 nm or less.

The amount of the silica is preferably 0.05 to 2.0 parts by weight, more preferably 0.1 to 1.0 part by weight, and further preferably 0.1 to 100 parts by weight, based on 100 parts by weight of the toner. It is 2 parts by weight to 0.8 parts by weight. When the added amount of the silica is less than 0.05 part by weight, the charge amount is raised and the effect of fluidity is small. When the added amount of the silica exceeds 2.0 parts by weight, the image density is reduced due to an increase in the charge amount. Malfunctions such as In addition, you may use together the silica surface-treated with other than silicone oil.

Also, in the present invention, under high temperature and high humidity,
While maintaining the amount of toner charge required for development, the charge on the toner particle surface is made uniform, the charge exchange between toner particles is accelerated, the charge speed is improved, and the charge distribution is sharpened. In order to greatly improve the environmental dependence of the charge amount of the toner composition, surface-treated titanium dioxide is added to the toner.

As the titanium dioxide, a titanium dioxide produced by a wet method and having a water-soluble component content of less than 0.2% by weight and surface-treated is used.

Here, the wet method is a method of producing a compound through a chemical reaction in a solvent, and the main production methods include a sulfuric acid method and a hydrochloric acid method.

In the sulfuric acid method, the liquid phase proceeds by the following reaction, and becomes insoluble hydrous titanium oxide. FeTiO ₃ + 2H ₂ SO ₄ → FeSO ₄ + TiOSO ₄ + 2H ₂ O TiOSO ₄ + 2H ₂ O → TiO (OH) ₂ + H ₂ SO _{4 In the} hydrochloric acid method, titanium tetrachloride is first dissolved in water.
At this time, the aqueous solution becomes an aqueous hydrochloric acid solution. Next, a strong base such as caustic soda is added to generate titanium hydroxide Ti (OH) ₄ , thereby precipitating titanium hydroxide.

Both the titanium oxide hydroxide and the titanium hydroxide are subjected to a sintering step to become titanium dioxide fine particles.

The water-soluble components include K ⁺ , Na ⁺ , Li ⁺ , and M contained in the conditioning agent and coagulant used in the production process.
g ²⁺ , PO ₄ ²⁻ , SO ₄ ²⁻ , Cl ^{− and the} like. For the measurement of the water-soluble component, 5 g of titanium dioxide was added to 250 ml of water.
This is carried out by evaporating 100 ml of the filtrate obtained by cooling, filtering after cooling, and then weighing the remaining amount. The details are described in JIS K5116-1973 {Titanium dioxide (pigment)}, and the amount of water-soluble component of the present invention is in accordance with this JIS, and the above-mentioned remaining amount is represented by% by weight based on the original titanium dioxide. Things.

As the surface treatment agent, various coupling agents such as a silane coupling agent, a titanate coupling agent, and an aluminum coupling agent, and silicone oil can be used. It is preferable to use a silane coupling agent because it prevents a reduction in the charge of titanium dioxide, improves its maintainability and hydrophobicity, and provides a high charge exchangeability and high image quality with less fogging.

Examples of the silane coupling agent include methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane. , Tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O-bis (trimethylsilyl) acetamide, N, N-bis (trimethylsilyl) urea, ter
t-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyl Typical examples thereof include trimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

The addition amount of the silane coupling agent is preferably 2 to 50 parts by weight, more preferably 10 to 30 parts by weight, per 100 parts by weight of titanium dioxide. When the amount of the silane coupling agent is less than 2 parts by weight, the effect of the silane coupling agent becomes insufficient, and when the amount of the silane coupling agent exceeds 50 parts by weight, the silane coupling agent is easily peeled. Carrier contamination is likely to occur. In addition, the resistance of the toner increases, and the initial chargeability decreases.

The addition amount of the surface-treated titanium dioxide is preferably 0.0
5 parts by weight to 2.0 parts by weight, more preferably 0.5 parts by weight to 1.5 parts by weight, still more preferably 0.7 parts by weight to 1.
1 part by weight. When the amount of the titanium dioxide is less than 0.05 part by weight, the effect of improving the charge exchange property is small, and when the amount of the titanium dioxide is more than 2 parts by weight, the image quality is deteriorated due to the impact of the carrier.

In the present invention, these silica fine particles and titanium dioxide fine particles are added to the toner at a predetermined weight ratio. The weight ratio of the silica fine particles to the titanium dioxide fine particles is preferably 1: 5.5 to 1:20, more preferably 1: 1.
5.5 to 1:10, more preferably 1: 5.5 to 1:
7 If the titanium dioxide particles are less than 5.5 with respect to the silica particles 1, the contribution of the silica particles is large and the charge amount increases. Further, when the titanium dioxide fine particles exceed 20 with respect to the silica fine particles 1, the image quality is deteriorated due to the impact of the carrier.

In order to make these silica fine particles and titanium dioxide fine particles adhere to the toner particle surface as an additive,
For example, a high-speed mixer can be used. Specifically, using a Henschel mixer or a V-type blender,
What is necessary is just to mix a toner particle and an additive.

The carrier used in the present invention is a resin-coated carrier in which a resin coating layer is formed on a core material, and the resin coating layer comprises a matrix resin and thermosetting resin fine particles dispersed in the matrix resin. Is formed.

The thermosetting resin fine particles preferably have a critical surface tension of 20 dyne / cm or more. When the critical surface tension is 20 dyne / cm or more, the dispersion stability of the thermosetting resin fine particles in the matrix resin is excellent, and the fine particles can be dispersed particularly uniformly in the matrix resin. From this viewpoint, the critical surface tension is 40 to 70 dyne / cm.
It is preferable that

Examples of the thermosetting resin usable for the thermosetting resin fine particles include a phenol resin; an amino resin such as a urea-formaldehyde resin, a melamine resin, a benzoguanamine resin, a urea resin, a polyamide resin; an epoxy resin; and diallyl phthalate. Resins; unsaturated polyester resins; polyimide resins; alkyd resins; xylene resins; petroleum resins; Further, these resins may be crosslinked. The thermosetting resin particles may be used alone or in combination of two or more.

The thermosetting resin particles used in the present invention preferably contain an N atom as a component thereof in order to impart a negative charge to the toner, and a crosslinked or non-crosslinked melamine resin is preferred. Used for

The average particle size of the thermosetting resin particles is 0.1 to
It is preferably 2 μm. More preferably 0.2 to
1 μm. The average particle size of the thermosetting resin particles is 0.1
If it is smaller than μm, dispersion in the resin coating layer is very poor, and if the average particle size of the thermosetting resin fine particles is larger than 2 μm, it will easily fall off from the resin coating layer and the original function cannot be maintained.

Further, the thermosetting resin fine particles are preferably contained in the range of 5% by weight to 50% by weight, particularly preferably in the range of 5% by weight to 30% by weight based on the total amount of the resin in the resin coating layer. When the content of the thermosetting resin fine particles is less than 5% by weight, the toner cannot be sufficiently charged, and when the content of the thermosetting resin fine particles is more than 50% by weight, the amount of the thermosetting resin fine particles from the carrier surface is reduced. It becomes easy to fall off.

The method for producing thermosetting resin fine particles is as follows.
Polymerization manufacturing methods such as suspension polymerization, emulsion polymerization, suspension polymerization, etc., a method in which monomers or oligomers are dispersed in a poor solvent and granulated by surface tension while performing a crosslinking reaction, and a low-molecular component and a crosslinking agent are melt-kneaded. And the like, followed by pulverization to a predetermined particle size by wind force and mechanical force.

The thermosetting resin fine particles are used in a matrix to maintain the same surface composition as when not used and to maintain a good charge-imparting ability to the toner even when worn from the surface of the coating layer due to long-term use. It is preferable that the resin is uniformly dispersed in the resin.

As the matrix resin of the resin coating layer of the carrier used in the present invention, polyolefin resins,
For example, polyethylene, polypropylene; polyvinyl and polyvinylidene-based resins, for example, polystyrene, styrene-acrylic resin, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol,
Polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin having organosiloxane bond or a modified product thereof; For example, polytrifluoroethylene, polytetrafluoroethylene, polyhexafluoropropylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, a copolymer of vinylidene fluoride and an acrylic monomer, vinylidene fluoride-fluoride Fluoroterpolymers such as fluorinated vinyl copolymers, terpolymers of tetrafluoroethylene-vinylidene fluoride-non-fluorinated monomers; polyesters; polyurethanes; polycarbonates;
Phenolic resins; amino resins such as urea-formaldehyde resins, melamine resins, benzoguanamine resins,
Urea resin, polyamide resin, epoxy resin and the like. These resins may be used alone or in combination of two or more. Further, the matrix resin and the resin of the thermosetting resin fine particles may be the same or different.

Examples of the carrier core material used in the present invention include magnetic metals such as iron, steel, nickel and cobalt; magnetic oxides such as ferrite and magnetite; and glass beads. From the viewpoint of using a magnetic brush method. Is
Preferably, it is a magnetic carrier. The average particle size of the carrier core material is generally 10 μm to 500 μm, and preferably 30 μm to 100 μm.

As a method for forming a resin coating layer containing thermosetting resin fine particles and a matrix resin on the surface of a carrier core material, for example, powder of the carrier core material is prepared by mixing a matrix resin, thermosetting resin fine particles and a solvent. Dipping method in which a resin coating layer forming solution is immersed in a resin coating layer forming solution, spray method in which the resin coating layer forming solution is sprayed on the surface of a carrier core material, and a resin coating layer forming method in which the carrier core material is suspended by flowing air. A fluidized bed method of spraying a solution, a kneader coater method of mixing a carrier core material and a resin coating layer forming solution in a kneader coater and removing a solvent may be mentioned.In the present invention, a kneader coater method is particularly preferably used. Can be

The solvent used for the solution for forming the resin coating layer is as follows:
There is no particular limitation as long as it dissolves the matrix resin. For example, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ethyl ketone, and ethers such as tetrahydrofuran and dioxane can be used.

The coating amount of the resin coating layer is 0.05 to 10 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the core material.
The range is 5 parts by weight.

On the other hand, the carrier is insulated along with the resin coating, and it becomes difficult for the carrier to function as a developing electrode at the time of development. A conductive material may be dispersed in the resin coating layer for the purpose of improving the reproducibility of the solid.

Examples of conductive materials usable in the present invention include metals such as gold, silver and copper; carbon black; titanium oxide; zinc oxide; semiconductive oxides; titanium oxide, zinc oxide, barium sulfate and boric acid. There is a material in which the surface of aluminum, potassium titanate powder, or the like is covered with tin oxide, carbon black, or a metal. Among the above, carbon black is preferred from the viewpoint of production stability, cost, and conductivity.
As such carbon black, known ones can be used, and the DBP oil absorption with good production stability is 50 to 250 m.
Carbon black in the range of 1/100 g is particularly preferred.

The electrostatic latent image developer having the above configuration charges the electrostatic latent image carrying roll, and then exposes the charged electrostatic latent image carrying roll with a light source such as a flash lamp to form the electrostatic latent image. It is applied to an image forming method in which a toner image (a visible image) is formed by moving toner adhered on a developer carrying roll to an electrostatic latent image on an electrostatic latent image carrying roll in the next developing step. can do.

[0057]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, “parts” means parts by weight. (Production of toner) Polyester resin (synthesized from bisphenol A-ethylene oxide 2 adduct, bisphenol A-propylene oxide 2 adduct, terephthalic acid, trimetritic acid, Mw = 14000, Tg = 62 ° C.) 87 parts by weight carbon black ( 7 parts by weight of BPL manufactured by Cabot Corporation 6 parts by weight of polypropylene wax (Viscol 660P manufactured by Sanyo Chemical Co., Ltd.) 6 parts by weight The above-mentioned raw materials are premixed with the above composition, and 3 parts by weight of water are added by a twin screw extruder. Was melt-kneaded while keeping the temperature at 110 ° C., rolled and cooled, and preliminarily pulverized by a hammer mill or the like. Thereafter, the mixture is finely pulverized by a jet mill, and fine and coarse powders are cut by an air classifier to obtain a volume average particle diameter of 9.
3 μm-sized toner particles were produced. For particle size measurement, use a Coulter Counter TA-II (aperture diameter 100μ)
m). (Production of Titanium Dioxide Additive) In the production of the following additives a and b, an average particle diameter of 15
nm rutile-type titanium dioxide (MT manufactured by Teica Co., Ltd.)
-150A) was used. In addition, titanium dioxide is 0.3
It contained 0% by weight of a water-soluble component. Titanium dioxide additive a To a mixed solvent of methanol-water (95: 5) in which 1.0 g of decyltrimethoxysilane is dissolved, add 10 g of titanium dioxide fine powder obtained by washing with water and reducing the amount of water-soluble components to 0.11% by weight. And ultrasonically dispersed. Next, after the methanol and the like in the dispersion were evaporated and dried by an evaporator, the dispersion was heat-treated in a dryer set at 120 ° C., pulverized in a mortar, and titanium dioxide a surface-treated with decyltrimethoxysilane was obtained.

Titanium dioxide additive b Titanium dioxide fine powder obtained by washing with a mixed solvent of methanol-water (95: 5) in which 2.0 g of decyltrimethoxysilane was dissolved to reduce the amount of water-soluble components to 0.11% by weight. 1
0 g was added and ultrasonically dispersed. Thereafter, the same treatment as in the production of the titanium dioxide additive a was performed to obtain titanium dioxide b. (Manufacture of carrier) Carrier A Ferrite particles (Average particle size: 45 μm) 100 parts by weight Toluene 14 parts by weight Perfluorooctylethyl methacrylate-methyl methacrylate copolymer (copolymerization ratio 8: 2, weight average molecular weight Mw: 40000, criticality) Surface tension: 24 dyne / cm 1.6 parts by weight Carbon black (Vulcan XC72, manufactured by Cabot Corporation, DBP oil absorption: 174 ml / 100 g) 0.16 parts by weight Melamine resin fine particles (critical surface tension: 60 dyne / cm, average particle) 0.3 μm) 0.3 parts by weight The above components except for the ferrite particles are dispersed with a stirrer for 10 minutes to prepare a solution for forming the resin coating layer, and the solution for forming the resin coating layer and the ferrite particles are further degassed in vacuum. After stirring in a mold kneader at a temperature of 60 ° C for 30 minutes,
The toluene was distilled off under reduced pressure to obtain Carrier A. Carrier B Ferrite particles (average particle size: 45 μm) 100 parts by weight Toluene 14 parts by weight Styrene-methyl methacrylate copolymer (copolymerization ratio 7: 3, weight average molecular weight Mw: 30,000, critical surface tension 30 dyne / cm) 5 parts by weight The above-mentioned components excluding the ferrite particles were dissolved by a stirrer for 10 minutes to prepare a resin coating layer forming solution. The resin coating layer forming solution and the ferrite particles were further placed in a vacuum degassing type kneader. After stirring at 30 ° C. for 30 minutes,
The toluene was distilled off under reduced pressure to obtain Carrier B. Example 1 100 parts of the above toner particles were treated with silicone oil-treated silica (TS72, manufactured by Cabot Corporation).
0.2) and 1.2 parts of the titanium dioxide additive a produced in the above example were added and mixed with a Henschel mixer to obtain a toner having silica fine particles and titanium dioxide fine particles adhered to the surface. .

6 parts of the toner and 94 parts of the carrier A manufactured in the above example were mixed to obtain a developer 1.

Example 2 100 parts of toner particles were treated with silicone oil-treated silica (manufactured by Cabot Corporation, T
S720) was added in an amount of 0.3 part, and the titanium dioxide additive b prepared in the above example was added in an amount of 2 parts, to thereby obtain a developer 2 in the same manner as in Example 1.

(Comparative Example 1) Silicone oil-treated silica (manufactured by Cabot Corporation, T
S720) was added and mixed with a Henschel mixer to obtain a toner having silica fine particles adhered to the surface.

6 parts of the toner and 94 parts of the carrier A manufactured in the above example were mixed to obtain a developer 3.

(Comparative Example 2) 5 parts of titanium dioxide additive a was added to 100 parts of toner particles and mixed with a Henschel mixer to obtain a toner to which fine particles of titanium dioxide had adhered.

6 parts of the toner and 94 parts of the carrier A manufactured in the above example were mixed to obtain a developer 4.

Comparative Example 3 0.2 parts of silica (R972 manufactured by Nippon Aerosil Co., Ltd.) not treated with silicone oil was added to 100 parts of toner particles. Two parts were added and mixed with a Henschel mixer to obtain a toner having silica fine particles and titanium dioxide fine particles adhered to the surface.

6 parts of the toner and 94 parts of the carrier A manufactured in the above example were mixed to obtain a developer 5.

(Comparative Example 4) Silica treated with silicone oil (manufactured by Cabot Corporation, T
S720) and 1.2 parts of rutile-type titanium dioxide (MT-150A manufactured by Teica Co., Ltd.) having an average particle size of 15 nm, which has not been treated with decyltrimethoxysilane, and mixed with a Henschel mixer. A toner having silica fine particles and titanium dioxide fine particles adhered to the surface was obtained.

6 parts of the toner and 94 parts of the carrier A manufactured in the above example were mixed to obtain a developer 6.

Comparative Example 5 0.2 part of silica (TS720, manufactured by Cabot Corporation) treated with silicone oil was added to 100 parts of the toner particles, and 1.2 parts of the titanium dioxide additive a produced in the above example was used. Were added and mixed with a Henschel mixer to obtain a toner having silica fine particles and titanium dioxide fine particles adhered to the surface.

6 parts of this toner and 94 parts of the carrier B manufactured in the above example were mixed to obtain a developer 7.

(Comparative Example 6) To 100 parts of the toner particles, 0.04 part of silica (TS720, manufactured by Cabot Corporation) treated with silicone oil and 1.2 parts of the titanium dioxide additive a produced in the above example were used. Were added and mixed with a Henschel mixer to obtain a toner having silica fine particles and titanium dioxide fine particles adhered to the surface.

6 parts of this toner and 94 parts of the carrier A manufactured in the above example were mixed to obtain a developer 8.

(Comparative Example 7) To 100 parts of the toner particles, 2.2 parts of silica (TS720, manufactured by Cabot Corporation) treated with silicone oil and 2.0 parts of the titanium dioxide additive a produced in the above Example were used. Were added and mixed with a Henschel mixer to obtain a toner having silica fine particles and titanium dioxide fine particles adhered to the surface.

6 parts of the toner and 94 parts of the carrier A manufactured in the above example were mixed to obtain a developer 9.

(Comparative Example 8) 100 parts of the toner particles were treated with 1.0 part of silica (TS720, manufactured by Cabot Corporation) treated with silicone oil, and 0.02 parts of the titanium dioxide additive a produced in the above example. Were added and mixed with a Henschel mixer to obtain a toner having silica fine particles and titanium dioxide fine particles adhered to the surface.

A developer 10 was obtained by mixing 6 parts of the toner and 94 parts of the carrier A manufactured in the above example.

Comparative Example 9 0.1 part of silica (TS720, manufactured by Cabot Corporation) treated with silicone oil was added to 100 parts of the toner particles, and 2.2 parts of the titanium dioxide additive a produced in the above example. Were added and mixed with a Henschel mixer to obtain a toner having silica fine particles and titanium dioxide fine particles adhered to the surface.

6 parts of the toner and 94 parts of the carrier A manufactured in the above example were mixed to obtain a developer 11.

(Evaluation Tests) These developers were used with Vivace 55 manufactured by Fuji Xerox Co., Ltd.
Perform an image quality evaluation test using a remodeling machine.
0 ° C, 90% RH) and low temperature / low humidity (10 ° C, 20%)
% RH), the image density (ID measurement by X-Rite) and fog level (limit sample) were evaluated at the initial stage, after 30,000 copies and 100,000 copies. The results are shown in Tables 1 and 2.

[0080]

[Table 1]

[0081]

[Table 2]

Tables 1 and 2 show that the image density after copying 30,000 sheets and 100,000 sheets in a high temperature / high humidity, low temperature / low humidity environment
At the fog level, the developers 1 and 2 are more
It turns out that it is superior to 11. Also, developer 1,
2 and Developers 8 and 9 having different addition amounts of silica surface-treated with silicone oil, the addition amount of silica is in the range of 0.05 to 2.0 parts by weight based on 100 parts by weight of toner. It can be seen that developers 1 and 2 can obtain more favorable results.

From the comparison between Developers 1 and 2 and Developers 10 and 11 having different addition amounts of the surface-treated titanium dioxide, the addition amount of the titanium dioxide is 0.05 to 2.0 to 100 parts by weight of the toner. Developer 1 contained in a range of 0 parts by weight,
It is understood that the result of 2 is more preferable. Further, in comparison with Developers 1 and 2 and Developer 5 containing silica and surface-treated titanium dioxide but not treating the silica with silicone oil, a developer using silica treated with silicone oil was used. 1 and 2 are hotter
After 100,000 copies in high humidity, low temperature and low humidity environment
Image density after 30,000 copies in low humidity environment
It can be seen that favorable results are obtained at a fog level after copying 30,000 or 100,000 copies in a high humidity, low temperature, low humidity environment.

In comparison with Developers 1 and 2 and Developer 6 containing silica and titanium dioxide treated with silicone oil but not having the titanium dioxide surface-treated, the surface-treated titanium dioxide was used. Developer 1,
2, 30,000 sheets in high-temperature, high-humidity, low-temperature, low-humidity environment
Image density after 10,000 copies, and after 100,000 copies in high-temperature, high-humidity, low-temperature, low-humidity environment, and 3 in high-temperature, high-humidity environment
It can be seen that favorable results can be obtained at the fog level after 10,000 copies.

Further, from the comparison between the developers 1 and 2 and the developer 7 using the carrier B containing no melamine resin fine particles, the developers 1 and 2 using the carrier A containing the melamine resin fine particles have higher temperatures and higher temperatures. It can be seen that favorable results are obtained in image density and fog level after copying 30,000 sheets and 100,000 sheets in a high humidity, low temperature, low humidity environment.

[0086]

According to the present invention having the above-described structure, the maintenance of high image quality can be greatly improved, and the image quality excellent in charge maintenance and environmental stability can be provided.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI G03G 15/08 507L (72) Inventor Susumu Yoshino 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Koichi Hamano 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. (72) Kaori Oishi Inventor: 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. (56) References JP-A-5-53369 (JP, A) JP-A-2-146606 (JP, A) JP-A-4-268573 (JP, A) JP-A-4-322257 (JP, A) JP-A-4-360158 (JP, A) JP-A-5-216281 ( JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/08 G03G 9/10

Claims (7)

(57) [Claims] 1. An electrostatic latent image developer comprising a toner containing a binder resin and a colorant, and a carrier having a core material and a resin coating layer covering the core material, wherein the toner includes the toner For 100 parts by weight, 0.05 to 2.0 parts by weight of hydrophobic silica surface-treated with silicone oil,
0.05 to 2.0 parts by weight of the surface-treated titanium dioxide is added, and the weight ratio of the silica to the titanium dioxide is 1: 5.5 to 1:20, and the resin coating layer is A resin coating layer in which thermosetting resin fine particles are dispersed and contained, wherein the thermosetting resin fine particles are made of a resin containing nitrogen atoms and having a critical surface tension of 40 to 70 dyne / cm , and the thermosetting resin is An electrostatic latent image developer characterized in that the fine particles have an average particle size of 0.1 to 2 μm. 2. The electrostatic latent image developer according to claim 1, wherein the amount of the resin coating layer is 0.5 to 5 parts by weight based on 100 parts by weight of the core material. 3. An average particle diameter of the carrier is 30 to 1
The electrostatic latent image developer according to claim 1, wherein the electrostatic latent image developer has a thickness of 00 μm. 4. The electrostatic latent image developer according to claim 1, wherein the titanium dioxide has been treated with a silane coupling agent. 5. The electrostatic latent image developer according to claim 4, wherein the amount of the silane coupling agent is 2 to 50 parts by weight based on 100 parts by weight of the titanium dioxide. 6. The toner has an average particle size of 5 to 12 μm.
The electrostatic latent image developer according to any one of claims 1 to 5, wherein m is m. 7. An image forming method for developing an electrostatic latent image on an electrostatic latent image carrier using a developer layer on a developer carrier, the developer layer comprising a carrier and a toner, To the toner are added 0.05 to 2.0 parts by weight of hydrophobic silica surface-treated with silicone oil and 0.05 to 2.0 parts by weight of surface-treated titanium dioxide with respect to 100 parts by weight of the toner. Wherein the weight ratio of the silica to the titanium dioxide is 1: 5.5 to 1:20, and the carrier has a core material and a resin coating layer covering the core material, wherein the resin coating layer has The thermosetting resin fine particles are dispersed and contained, and the thermosetting resin fine particles contain a nitrogen atom and have a critical surface tension of 40.
An image forming method comprising a resin of about 70 dyne / cm and a thermosetting resin fine particle having an average particle diameter of 0.1 to 2 μm.