JPH0246470A - Carrier for developing electrostatic image - Google Patents

Abstract

PURPOSE:To increase a film strength of the title carrier, to stabilize charging characteristic of the carrier, and to prevent scattering of toner by providing a layer for controlling frictional electricity contg. fine silicone resin particles interposing an intermediate layer formed in a core material. CONSTITUTION:A frictional electricity controlling layer (D) contg. fine silicone resin particles (C) is formed on a core material (A) interposing an intermediate layer (B). It is preferred that the mean particle size of the particle (C) is smaller than the thickness of the layer (D) and <=3mum. Particles of a magnetic body such as ferrite particles may be used for the core (A), and a styrenic and/or (meth)acrylic (co)polymer having high adhesion to the material for the core (A) and the material of the layer (D) may be used for the layer (B). Further, fine particles of three-dimensionally setting polysiloxane, etc. may be used for the particles (C), and a fluorovinylidene-tetrafluoroethylene type copolymer and/or fluoroalkyl (meth)acrylate type copolymer may be used for the layer (D).

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a carrier for developing an electrostatic image used when a charged electrostatic image is visualized with toner particles. The present invention relates to a carrier for electrostatic image development, in which a triboelectric charge control layer containing fine silicone resin particles is provided on the intermediate layer.

[Background of the Invention] A two-component developer consisting of a toner and a carrier can control the charge polarity and charge amount of the toner to a considerable extent, and also has a wide range of colors that can be applied to the toner. There is an advantage.

In this type of developer, the core material of the carrier is coated with resin in order to control the triboelectricity of the toner, prevent deterioration of the carrier, prevent damage to the surface of the photoreceptor, extend the life of the developer, and maintain recorded image quality. There are many things. As one of them,
In order to properly and stably impart electric charge to toner particles, there is a coated carrier in which a triboelectric charge control layer is coated on a core material.

This type of coated carrier has conventionally been known as a single-layer carrier in which a triboelectric charge control layer is directly coated on a core material. Furthermore, in recent years, multilayer coated carriers coated with a plurality of layers have been developed and put into practical use in place of single-layer carriers in order to improve the charging characteristics of carriers, adhesion with core materials, and the like.

When a resin having a low surface energy is used as the triboelectric charge control layer, the toner is not adsorbed to the carrier surface, and the charging characteristics of the carrier can be more stabilized, so its use has been desired.

Fluororesins and silicone resins are known as such low surface energy resins.

[Problems to be Solved by the Invention] However, since fluororesins and silicone resins do not have sufficient film strength, when used as the outermost triboelectric charge control layer, they wear out with repeated use. For this reason, the coverage of the triboelectric charge control layer decreases, the charging characteristics of the carrier change, and the toner scatters outside the developing device when the developer is transported and comes into contact with the photoreceptor, leading to contamination inside the device. Therefore, when using these resins, it is necessary to increase the film strength.

By the way, as a conventionally known carrier using a silicone resin, there are the following although it is a single layer.

JP-A-50-2543 discloses a carrier using a halogen-substituted silicone polymer.

However, this silicone resin has extremely low film strength, and if the carrier is used repeatedly, the silicone resin film on the surface will wear out.

JP-A-55-127569 discloses a carrier made of a room-temperature curing silicone resin and a positively chargeable nitrogen-containing resin. This attempts to improve the film strength by using a room-temperature curing type, but a film strength sufficient for practical use has not been obtained.

JP-A No. 58-184951 discloses that in order to coat the uncured portion of the carrier surface with 30% by weight or less of silicone resin, heating is performed at 200 to 300°C to carry out a curing reaction. has been done. Since the curing reaction is actively progressing, the film strength is sufficient.

However, this method requires a heat treatment process,
As the number of manufacturing steps increases, granulation tends to occur during the heat treatment process, and a loosening process is required to loosen the granules.

Furthermore, the amount of triboelectrification of silicone resins varies greatly due to slight fluctuations in the temperature conditions in which the curing reaction proceeds, so it is extremely difficult to produce carriers with stable performance.

On the other hand, in a multi-layer coated carrier, a technique for containing a low surface energy fluororesin and/or silicone resin in the outermost triboelectric charge control layer was disclosed in JP-A-61-1.
No. 10159, No. 61-110160, No. 6
It is disclosed in 2-39879 and 62-39880.

Since the materials disclosed in these documents are multilayer coated carriers, they have excellent adhesion between the triboelectric charge control layer and the core material.
Furthermore, since the triboelectric charge control layer contains a low surface energy resin, the image quality is high at the initial stage of running, and the charging characteristics are also stabilized.

However, in all of these, since the resin is not actively cured, the film strength is insufficient, and as the number of running sheets increases, the resin wears out and the performance at the initial stage of running cannot be maintained.

As described above, conventionally, when realizing an electrostatic image developing carrier having a triboelectric charge control layer made of a low surface energy resin, there have been various problems to be solved in terms of quality and manufacturing.

The present invention has been made to solve the above-mentioned problems caused by using a low surface energy resin in a triboelectric charge control layer in a multilayer electrostatic image developing carrier.

A first object of the present invention is to provide a carrier for electrostatic image development that has strong film strength. Therefore, since the coverage of the triboelectric charge control layer does not change even after repeated use, it is possible to provide a carrier for electrostatic image development that has stable charging performance and has a long life without toner scattering.

A second object of the present invention is to provide a carrier for electrostatic image development that does not require heat treatment to cure the resin constituting the triboelectric charge control layer. Therefore, the process can be simplified and granulation does not occur. Further, it is possible to provide an electrostatic image developing carrier whose triboelectric charging performance does not change during heat treatment and whose manufacturing quality is stable.

In addition to these, the third object of the present invention is to improve the adhesion between the triboelectric charge control layer and the core material by adopting a multilayer coating structure, so that the electrostatic image that the triboelectric charge control layer is difficult to peel off from the core material is obtained. The purpose of the present invention is to provide a carrier for development. In addition, the characteristics of the core material do not affect the carrier surface.
A carrier for electrostatic image development with excellent charging properties can also be provided.

[Means for Solving the Problems] As a means for solving the above problems, the present invention provides a carrier for electrostatic image development comprising an intermediate layer on a core material, in which triboelectric charging is controlled on the intermediate layer. It is characterized in that it has a triboelectric charge control layer made of resin, and the triboelectric charge control layer contains silicone resin fine particles.

In the electrostatic image developing carrier, the average particle size of the silicone resin particles is preferably smaller than the thickness of the triboelectric charge control layer.

In the carrier for developing an electrostatic image, it is preferable that the average particle size of the silicone resin particles is 3 μm or less.

In order to increase the film strength of silicone resin and fluororesin, which are preferably used as the triboelectric charge control layer of the multilayer coated carrier, so that they can withstand repeated use,
We have been conducting intensive research. As a result, they came up with the idea that the film strength could be increased by dispersing and containing silicone resin fine particles in the triboelectric charge control layer.

It has been known that three-dimensional crosslinking can be carried out by heat treatment in order to increase the film strength of silicone resins and fluororesins, but this method increases the number of heat treatment steps and tends to cause granulation. The present invention does not have such drawbacks and can increase the film strength.

In the electrostatic image developing carrier of the present invention, silicone resin fine particles are embedded on the surface and/or near the surface of the triboelectric charge control layer.

The film thickness of the triboelectric charge control layer in the present invention is calculated from the resin coating amount and the average particle diameter of the carrier. Specifically, the thickness of the resin coating layer is expressed by:

In the present invention, the average particle size of the silicone resin fine particles is
0.05 g of silicone fine particles are ultrasonically dispersed in an aqueous surfactant solution. The dispersion liquid was placed in a measurement cell (1an x 1
■Put it in a centrifugal automatic particle size distribution analyzer CAPA-500 (manufactured by Horiba, Ltd.), and
The rotation speed was measured in pm.

The average particle diameter of the silicone resin fine particles used in the present invention is preferably 3 μm or less, and more preferably 0.05 to 3 μm.
0.5 μm is preferred. In the commonly used carrier for electrostatic image development, the layer thickness of the triboelectric charge control layer is 3 μm or less, so if the average particle size of the silicone resin particles is 3 μm or more, they protrude from the layer surface and are missing. It's easy to do.

The content of the silicone resin fine particles relative to the resin constituting the triboelectric charge control layer is preferably 5 to 50% by weight, more preferably 10 to 20% by weight.

If the content is less than 5% by weight, the film strength will not increase enough to achieve the objective of the present invention, and if the content is more than 50% by weight, the film will become brittle.

The silicone resin fine particles preferably used in the present invention will be specifically described below, but the present invention is not limited thereto.

Repeating units include vinyltrichlorosilane, vinyltris(βmethoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-(methafluroxypropyl)trimethoxysilane, β-(3,4epoxycyclohexyl)ethyltrimethoxy Silane, γ-
Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyljethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N
-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-7minoprobyltriethoxysilane,
Silicone resins made of N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, polysiloxane, and copolymers containing two or more of these repeating units may also be used.

Further, curable silicone fine particles are preferably used because they can impart suitable hardness and wear resistance to the carrier. In particular, silicone fine particles having an uncured content of 30% or less are preferred.

Core materials for the carrier used in the present invention include inorganic powders such as glass peas, metal powders such as aluminum powder, iron powder and nickel powder, metal oxide powders such as iron oxide, ferrite and magnetite, and carbonium iron powders. Materials used as the core material of conventional coat carriers can be used, such as organic metal powders.

Among these, the present invention is particularly effective when using magnetic particles such as iron powder and ferrite powder.

Note that ferrite herein is a general term for magnetic oxides containing iron, and is not limited to spinel type ferrite shown by the chemical formula MO-Fe203.

In addition, in the above chemical formula, M represents a divalent metal, and specifically represents nickel, copper, zinc, manganese, magnesium, lithium, etc.

The core material is usually formed by coating the core material with an intermediate layer and a triboelectric charge control layer, and the particle size of the carrier particles is 10 to 500 μm.
The particle size is determined such that m. The core material preferably has a particle size within a certain range. Usually, the above-mentioned core materials are used after being classified. Also,
There are no particular restrictions on the shape of the particles of the core material. However, in consideration of the powder characteristics of the resulting carrier, a spherical or ellipsoidal carrier is preferable.

The size of the magnetic particles such as iron powder and ferrite powder is preferably in the range of 20 to 200 μm, with a weight average particle diameter of 30 μm.
It is more preferable if it is in the range of ~120 μm. If it is smaller than 20 μm, development in which the carrier adheres to the latent image carrier is likely to occur.

On the other hand, if it is larger than 200 μm, the image will be coarse-grained.

Considering the powder properties of the resulting carrier, it is desirable that the magnetic particles be spherical or ellipsoidal. More specifically, it is preferable that the magnetic particles have a circularity of 0.70 or more. When such magnetic particles with high circularity are used, the obtained coated carrier has high circularity, so the fluidity of the carrier increases,
As a result, it becomes possible to stably convey an appropriate amount of toner to the developing space, and more excellent developing performance is exhibited.

Here, the circularity is defined by the following formula.

This circularity can be measured using, for example, an image analysis device (manufactured by Nippon Avionics Co., Ltd.).

A preferred exploitation of the invention is a two-layer structure. That is,
This carrier has one intermediate layer on a core material, and one triboelectric charge control layer containing silicone resin fine particles as the outermost layer on the intermediate layer.

The intermediate layer is required to have good film formability. That is, since the core material and the triboelectric charge control layer containing fine silicone resin particles are firmly bonded by the intermediate layer, the layer thickness of the triboelectric charge control layer containing fine silicone resin particles becomes uniform. Therefore, the carrier to be prepared has a narrow particle size distribution and a uniform particle size.

Further, the intermediate layer is required to have a shielding effect that prevents the characteristics of the core material from becoming apparent on the carrier surface.

This shielding effect provides the carrier with significantly improved imaging performance in continuous use.

In the present invention, it is preferable that the specific resistance of the core material to which the intermediate layer is adhered and fixed is I x 1012 Ω·mark or more,
It is more preferable that this value is 1×10 13 Ω·■ or more.

Setting the specific resistance to the above value means that the core material is completely covered with the intermediate layer. Therefore, the characteristics of the core material are completely shielded, and electrical conductivity etc. do not affect the carrier surface.

In order to make the resistivity higher than the above value, it is desirable to form a uniform intermediate layer on the surface of the core material. By forming a triboelectric charge control layer containing silicone resin fine particles (described later) on such a uniform intermediate layer, the core material and the triboelectric charge control layer containing silicone resin fine particles are firmly bonded by the intermediate layer. It is from. Furthermore, the triboelectric charge control layer containing fine silicone resin particles also becomes uniform. Therefore, the electrostatic latent image developer prepared using the carrier of the present invention has a narrow particle size distribution during production and has a uniform particle size. Moreover, it has good mechanical durability and good durability during continuous use.

As the resin component forming the intermediate layer, a resin having good adhesion to the core material and the triboelectric charge control layer containing silicone resin fine particles, which is the outer layer thereof, and having high electrical insulation properties is used. In the case of the present invention, resins that do not dissolve in solvents can also be used.

Examples of resins that form such an intermediate layer include styrenic resins (styrene homopolymer, styrene and alkyl (styrene homopolymer),
Copolymers with meth)acrylates, etc.) Epoxy resins (
Copolymers of bisphenol A and epichlorohydrin, etc.), acrylic resins (polymethyl methacrylate, etc.), polyolefin resins (polyethylene resins, LLDPE, etc.)
, polybutadiene resin, etc.), polyurethane resin (polyurethane resin, polyester/polyurethane resin, etc.)
, nitrogen-containing vinyl copolymers (polyvinylpyridine, etc.),
Polyester resins (polymers manufactured from diols such as ethylene glycol and divalent organic carboxylic acids such as maleic acid or phthalic acid, etc.), polyamide resins (6-nylon, 6-6 nylon, etc.), polycarbonates (polymers manufactured from phthalic acid, etc.) Polyethylene, etc.), cellulose derivatives such as trocellulose, alkyl cellulose, etc.) and silicone resins.

In particular, styrene and acrylic resins are preferred as the resin forming the intermediate layer of the carrier.

Styrene and acrylic resins have good adhesion with fluororesins that are sometimes used for core materials and triboelectric charge control layers, so they improve the mechanical strength of the resulting carrier and can be used with other resins. The charge imparting properties are more stable than in the case where the Furthermore, even if the carrier for electrostatic latent image developer is stored or used for a long time under high-temperature conditions (e.g., temperature: 30"C, humidity: 80%), there is almost no change in the charge imparting properties of the carrier. , Furthermore, there is little deterioration in powder properties.

Examples of the styrenic resin forming the intermediate layer include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene,
Alkylstyrenes such as triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene and octylstyrene, halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dipromostyrene and iodostyrene, nitrostyrene, acetylstyrene and methoxy Homopolymers of styrene monomers such as styrene, homopolymers of alkyl (meth)acrylate monomers consisting of methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and copolymers thereof One example is merging.

The carrier of the present invention has a triboelectric charge control layer containing silicone resin fine particles on the above-mentioned intermediate layer.

The resin that forms the triboelectric charge control layer containing silicone resin fine particles may be not limited to those soluble in solvents, such as (meth)acrylate resins, styrene resins, nitrogen-containing vinyl resins, and fluorine-based resins. Resin, silicone resin, etc. can be used.

Preferred embodiments of the fluororesin will be described below, but the invention is not limited thereto.

As the fluororesin, vinylidene fluoride-tetrafluoroethylene copolymers and/or fluorinated alkyl (meth)acrylate copolymers are suitable. These fluororesins can be used alone or in combination.

However, when using a fluororesin, repeating units having fluorine atoms in this layer (for example, when using a vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride repeating units and tetrafluoroethylene repeating units) (in addition, when using a fluorinated alkyl (meth)acrylate copolymer, a fluorinated alkyl (meth)acrylate repeating unit)
It is preferable that the content of is more than 50% by weight,
More preferably, it is 55% by weight or more.

The content of repeating units containing fluorine atoms is 50% by weight.
By increasing the amount, the initial charge amount of the toner can be generally within the range of +10 to +40 μc/g, and the chargeability of the carrier is further stabilized.

In the carrier of the present invention, the content of the fluororesin to the core material is preferably 0.2 to 5% by weight, and 0.5 to 3% by weight.
% by weight is more preferred, and 1-3% by weight is most preferred.

The thickness of the triboelectric charge control layer containing silicone resin fine particles is preferably 0.5 μm or more, more preferably 1 μm or more.
．． It is 0 to 2.0 μm.

When using a fluorinated alkyl (meth)acrylate polymer as the fluororesin, examples of the fluorinated alkyl (meth)acrylate repeating unit, which is a repeating unit containing a fluorine atom, include the repeating unit represented by the following formula [1] Can list units.

-(-CI-12-CR" -) 0=C-R2...[1] However, in formula [1], R1 represents a hydrogen atom or a methyl group, and R2 represents a hydrogen atom in which at least one hydrogen atom is fluorine. It is a residue obtained by removing hydrogen from the hydroxyl group of an alcohol compound containing an alkyl group substituted with an atom.

Examples of alcohol compounds that can form a residue represented by R2 include perfluoroalcohols having 1 to 18 carbon atoms (perfluoromethanol, perfluoroethanol, perfluoropropanol, perfluorobutanol, perfluoropentanol, perfluoro 1,1-dihydroperfluoroalcohol or trihydroperfluoroalcohol represented by the following formula, CF2X (CF2), CH20H (However, n is usually 0 or an integer from 1 to 16, and X is either a hydrogen atom or a fluorine atom. Specific examples include ■, 1-dihydroperfluoroethanol, ■, 1- dihydroperfluoropropanol,
1,1-dihydroperfluorohexanol, 1.1-
Dihydroperfluorooctyl alcohol, 1,1-dihydroperfluorolauryl alcohol and 1,1-
Difluorostearyl alcohol and 1,1,2-
Trifluoroethanol, 1,1,3-trifluoropropanol.

1.1.4- Trifluorobutanol, 1,1.5-
Mention may be made of trifluoropentanol and 1,1,18-trifluorostearyl alcohol. ); Tetrahydroperfluoroalcohol CH3 (CF2), (CH2Cl+2) (CF2) □ represented by the following formula
011 (However, usually, n is O or an integer from 1 to 15, and m is 0 or 1. As a specific example,
1,1,2.2-tetrahydroperfluoroethanol, 1,1,2.2-tetrahydroperfluoropropanol, 1,1,2.2-tetrahydroperfluorohexanol, 1,1,2.2-tetrahydroperfluoro Octyl alcohol, 1,1,2.2-tetrahydroperfluorolauryl alcohol, 1,1,2.2-tetrafluorostearyl alcohol and 2,2,3.3
-Tetrafluoropropanol. ); Other fluoroalcohols (2,2,3,3,4.4
-tetrafluoropropanol, 1,1,ω-trihydroperfluorohexanol, 1,1,ω-trihydroperfluorooctatool, 1,1,1,3,3.3-
hexafluoro-2-propatur, etc.); acetylnarcol fluoride (3-perfluorononyl-2-acetylpropatur, 3-perfluorolauryl-2-acetylpropatur, etc.); N-fluoroalkylsulfonyl-N- Alkylamino alcohol (N-perfluorohexylsulfonyl-N-methylaminoethanol, N-
Perfluorohexylsulfonyl-N-butylaminoethanol, N-perfluorooctylsulfonyl-N-
Methylaminoethanol, N-perfluorooctylsulfonyl-N-ethylaminoethanol, N-perfluorooctylsulfonyl-N-butylaminoethanol, N-perfluorodecylsulfonyl-N-methylaminoethanol, N-perfluorodecylsulfonyl- Ethylaminoethanol, N-perfluorodecylsulfonyl-N-butylaminoethanol, N-perfluorolaurylsulfonyl-N-methylaminoethanol, N
-Perfluorolaurylsulfonyl-N-ethylaminoethanol and N-perfluorolaurylsulfonyl-
N-butylaminoethanol, etc.).

In particular, as the fluorinated alkyl (meth)acrylate repeating unit, those described below are desirable.

- (-C12-CR'-) 0=COCH2CF3 - (-CH2-CR''-) 0 = COCH2 (CF2)Z H- (-C
H2-CR''-) - 〇=COC■2CF2CF3 However, in the above formula, R1 is the same as above.

(Left below) The fluororesin used in the carrier of the present invention is a vinylidene fluoride-tetrafluoroethylene copolymer consisting only of the above vinylidene fluoride repeating units and tetrafluoroethylene repeating units, or Alkyl (
The copolymer may contain a single meth)acrylate repeating unit, or may contain other repeating units. However, the content of the above-mentioned fluorine atom-containing repeating units (total of vinylidene fluoride repeating units and tetrafluoroethylene repeating units) in the fluororesin is preferably 50% by weight or more, more preferably 55% by weight or more. % by weight or more.

If the content of the above repeating units in the fluororesin is lower than 50% by weight, the charge imparting properties of the carrier may vary depending on the types of other repeating units.

In the present invention, examples of other repeating units that can form a vinylodane fluoride-tetrafluoroethylene copolymer together with the vinylidene fluoride repeating unit and tetrafluoroethylene repeating unit, and alkyl(meth)fluoride Examples of other repeating units that can form a fluorinated alkyl (meth)acrylate polymer with the acrylate repeating unit include the following.

Repeating units derived from aliphatic olefins (ethylene, propylene, butene-1, etc.), repeating units derived from halogenated aliphatic olefins, vinyl chloride, vinyl bromide, vinyl iodide, 1,2-dichloroethylene ,
1,2-dibromoethylene, 1,2-diiodide ethylene, isopropenyl chloride, allyl chloride, allyl bromide, etc.),
Repeating units derived from conjugated diene aliphatic diolefins (1,3-butadiene, 1,3-pentadiene,
2-methyl 1,3-butadiene, 2,3-dimethyl-1
, 3-butadiene, 2,4-hexadiene, 3-methyl-2,4-hexadiene, etc.), repeating units derived from aromatic vinyl compounds (styrene, methylstyrene, etc.), and nitrogen-containing vinyl compounds. Repeating units derived (2-vinylpyridine, 4-vinylpyridine, 2-vinyl-6-methylpyridine, 2-vinyl-5-methylpyridine, 4-butenylpyridine, 4-pentylpyridine, N-vinylpyridine, 4-vinylpyridine, vinylhydropiperidine,
4-vinyldihydropiperidine, N-vinylhydropiperidine, N-vinylpyrrole, 2-vinylpyrroline, N
-vinylpyrrolidine, 2-vinylpyrrolidine, N-vinyl-2-pyrrolidone, N-vinylcarbazole, etc.). These can be used alone or in combination of two or more.

The above-mentioned repeating unit is preferably a repeating unit derived from an aromatic vinyl compound, a styrene repeating unit, a methylstyrene repeating unit, or a methyl (meth)acrylate repeating unit.

The electrostatic image developing carrier of the present invention can be produced, for example, by the following method.

A coating solution prepared by dissolving the resin forming the intermediate layer in an organic solvent is applied onto the core material to form the intermediate layer. Further, a resin constituting the triboelectric charge control layer is dissolved in a liquid obtained by ultrasonically dispersing silicone fine particles in an organic solvent. The coating liquid prepared in this manner is applied onto the core material on which the intermediate layer is formed.

The method of applying the intermediate layer and the triboelectric charge control layer is not particularly limited. Further, after dissolving the triboelectric charge control layer in an organic solvent, the silicone fine particles may be dispersed by ultrasonic waves.

Dry coating can also be used as a method for producing the intermediate layer and/or triboelectric charge control layer of the carrier for electrostatic image development of the present invention.

First, magnetic particles and resin particles are mixed and stirred uniformly using, for example, a normal stirring device, and the resulting mixture is transferred to, for example, a device that is an improved version of a normal impact-type crushing device, and then, for example, By repeatedly applying an impact force for 1 to 20 minutes, the resin particles forming the intermediate layer are adhered and fixed to the surface of the magnetic particles, thereby obtaining the carrier intermediate of the present invention.

Next, this intermediate (magnetic particles to which resin particles are adhered and fixed), the resin constituting the triboelectric charge control layer, and the silicone resin fine particles are mixed and stirred, for example, in the same manner as above, using a normal stirring device or the like. Mix uniformly, and the resulting mixture
For example, by transferring a normal impact crushing device to an improved device and applying impact force repeatedly over a period of 1 to 20 minutes, the surface of the intermediate is coated with a triboelectric charge control layer containing fine silicone resin particles. The final object, the coated carrier, is obtained by fixing the coated carrier.

An example of an apparatus preferably used in the dry manufacturing method is shown in FIG.

In the figure, 11 is a raw material input valve, 12 is a raw material input chute, 13 is a product discharge valve, 14 is a product discharge chute, 1
5 is a rotating disk (rotor), 16 is a blade provided on the rotating disk 15, 17 is a stator, 18 is a recycling pipe, 19 is a jacket (can be cooled or heated), 2
0 is a casing, and 21 is a temperature needle using a chromel-alumel thermocouple as a temperature measuring probe. Further, the recycling piping 18 and the input and discharge chutes 12 and 14 may have a jacket structure to cool or heat them.

In this apparatus, for example, in coating the triboelectric charge control layer, intermediates (magnetic particles to which resin particles are adhered and fixed) sealed from the raw material input valve 11, resin particles constituting the triboelectric charge control layer, The mixture of fine particles of silicone resin is rotated and dispersed by the rotary disk 15 and blades 16, and is subjected to impact force by collisions with the rotary disk 15, blades 16, and stator 17, and collisions between the particles, and the frictional charge control layer is The constituent resin particles and silicone resin fine particles are attached and spread on the surface of the intermediate, and are further subjected to such impact force repeatedly while circulating through the recycling pipe 18, thereby achieving dry coating. In the figure, arrows indicate trajectories of raw material particles and the like.

Furthermore, the apparatus shown in FIG. 1 above can also be used when coating an intermediate layer.

The total layer thickness of the intermediate layer of the carrier of the present invention and the triboelectric charge control layer containing fine silicone resin particles is arbitrary depending on the type of carrier, but is preferably 3 μm or less. In the case of dry coating, the resin particles to be coated are preferably 1 μm or less in size.

The toner particles used with the carrier of the present invention are positively or negatively charged toner particles containing a positively or negatively charged resin and/or a colorant.

The mixing weight ratio of the carrier and toner particles of the present invention is arbitrary, but the ratio of toner particles:carrier 1:99 to 10:
90 is preferable, and 2:98 to 8:92 is more preferable.

The carrier and toner particles can be mixed according to conventional methods.

The toner of the present invention is preferably used in combination with inorganic fine particles such as a fluidity improver.

The inorganic fine particles used in the present invention include -
The secondary particle size is 5 nm to 2 μm, preferably 5 nm to 2 μm.
The particle size is 500 nm. Further, the specific surface area determined by the BET method is preferably 20 to 500+rr/g.

The proportion mixed in the toner is 0.01 to 5% by weight,
Preferably it is 0.01 to 2.0% by weight.

Examples of such inorganic fine powder include fine silica powder, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite,
Examples include diatomaceous earth, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride, and silica fine powder is particularly preferred.

The silica fine powder referred to herein is a fine powder having a Si-0-Si bond, and includes both those manufactured by a dry method and a wet method. Further, in addition to anhydrous silicon dioxide, any of aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, zinc silicate, etc. may be used, but those containing 85% by weight or more of SiO□ are preferable.

=31- Specific examples of these fine silane powders include various commercially available silicas, but those having hydrophobic groups on the surface are preferred;
For example, AERO3IL R-972, R-974°R
-805, R-812 (manufactured by Aerosil), Taranox 500 (manufactured by Talco), and the like.

Other silane coupling agents, titanium coupling agents,
Silica fine powder treated with silicone oil, silicone oil having an amine in its side chain, etc. can be used.

[Operations and Effects] The present invention is characterized in that an intermediate layer is provided on the core material, and the triboelectric charge control layer on the intermediate layer further contains silicone resin fine particles.

According to the present invention, since the cured silicone resin particles are on the surface and/or near the surface of the triboelectric charge control layer, it is possible to increase the film strength, and even when subjected to impact force, the triboelectric charge control layer is not damaged. does not occur.

Therefore, there is no change in coverage, the amount of triboelectric charge is stable, there is no toner scattering, and the life of the carrier can be extended.

Furthermore, no heat treatment step is required to increase the film strength of the carrier. Therefore, no granulation occurs and no granulation loosening step is required. Furthermore, since the triboelectric charging performance does not fluctuate during heat treatment, manufacturing quality is stable.

Since the electrostatic image developing carrier of the present invention has a multilayer coating structure, the adhesion between the triboelectric charge control layer and the core material is improved.
The triboelectric charge control layer is difficult to peel off from the core material. Furthermore, since the properties of the core material do not affect the surface of the carrier, the triboelectric charging performance can be more stabilized.

[Examples] Examples of the present invention will be described below. Note that the present invention is not limited to these examples.

(Production of carrier) Example-1 Mixed solvent of toluene and methanol (weight ratio: 9:
1) 20g of methyl methacrylate-styrene copolymer (copolymerization molar ratio = 4:6゜Mw = 1) in 400mQ
34000. A coating liquid for forming an intermediate layer was prepared by dissolving Mw/Mn=1.9, elastic modulus at 40° C.=1.3×10”dyne/cJ).

Using this coating liquid, 2 kg of spherical ferrite core material (manufactured by Nippon Tetsuko Co., Ltd., F = 150. Volume average particle size 80 μm (
Hereinafter, D5o:=80 μm), specific resistance=
An intermediate layer was formed on the surface (7.4×10′Ω・all) using a fluid transfer coating device, Spira Coater (manufactured by Okada Seiko Co., Ltd.).

At this stage, a part of the core material on which the intermediate layer was formed was extracted and used as a sample for measuring electrical resistance (specific resistance of the core material on which the intermediate layer was formed = 9.OX, 1013Ω・an). The average thickness of the intermediate layer calculated from the surface area of the core material and the amount of methyl methacrylate-styrene copolymer used is 0.
It was 6 μm.

Next, 0.6 g of three-dimensional crosslinked polysiloxane resin particles (D5o=0.2 μm) represented by the compound (,) as silicone resin particles were added to 800 nIQ of acetone, and ultrasonic sound dispersion was performed for 10 minutes.

A coating liquid was prepared by dissolving 34.0 g of a fluorinated alkyl (meth)acrylate resin represented by compound (b) (D5o=0.2 μm) as a resin constituting the triboelectric charge control layer in this solution.

The obtained coating liquid was applied onto the intermediate layer using a fluid transfer coating device Spira Coater (manufactured by Okada Seiko Co., Ltd.).
A triboelectric charge control layer was formed and a carrier was manufactured.

(0-Si-0). -... Compound (a) 0=C-O
CH2-CF3 Example-2 Silicone resin fine particles composed of the same basic unit as compound (a) used in Example-1 had a particle size of Ds[l
A carrier was produced in the same manner as in Example-1, except that 4.0 g of silicone resin fine particles having a diameter of 0.5 μm and 36.0 g of the compound (b) used in Example-1 were used.

Example-3 12.0 g of silicone resin fine particles used in Example-1 and compound (b) as a resin constituting the triboelectric charge control layer
A carrier was produced in the same manner as in Example-1 except that 28.0 g was used.

Example-4 Ferrite carrier DFC-150 (manufactured by Dowa Iron Powder Co., Ltd., D
5. = 80 μm) 2000 parts by weight and methyl methacrylate-butyl methacrylate-1 copolymer (D, . = 0
．． (15 μm) and 20 parts by weight were mixed for 20 minutes using a YGG mixer (manufactured by Yayoi Co., Ltd.) to form an ordered mixture.

This mixture was prepared using a hybridizer-NHS-1 type ((
Nara Kikai Seisakusho Co., Ltd.) was modified as shown in Figure 1 to apply an impact force of 10 at a rotational speed of 700 rpm at room temperature.
The intermediate layer was applied repeatedly for several minutes, and the intermediate layer was adhered and fixed to the core material by dry coating.

Subsequently, 2 kg of the core material to which the intermediate layer was adhered and fixed, 34.0 g of the compound (b) used in Example-1, and Example-1
The three-dimensionally crosslinked polysiloxane resin fine particles (DS
. = 0.2 μm) 6.0 g in the same way as the intermediate layer,
A carrier with a triboelectric charge control layer adhered and fixed by dry coating was produced.

Comparative Example-1 Without using silicone resin fine particles in Example-1,
A carrier was produced in the same manner as in Example-1 except that the amount of compound (b) was changed to 4.0 g.

Comparative Example-2 After coating in the same manner as in Example-1 except that 35 g of silicone resin SR 2406 (manufactured by Tray Silicone) was used without using compound (b), it was placed in an electric oven at 250°C for 2 hours. The carrier was produced by firing.

Example-A Average particle size having the same basic unit as compound (a) is 0.8μ
6.0 g of silicone resin fine particles of m and compound (b)
A carrier with a triboelectric charge control layer having a thickness of 0.91 μm was produced in the same manner as in Example 1, except that 24.0 g of the triboelectric charge control layer was used.

Example-B Average particle size having the same basic unit as compound (a) is 2.8μ
18.0 g of silicone resin fine particles of m and a compound (
Using 72.0 g of b), the thickness of the triboelectric charge control layer was 3.
．． A carrier was manufactured in the same manner as in Example-1 except that the thickness was 0 μm.

Comparative Example-C Has the same basic unit as compound (,) and has an average particle size of 1.1
6.0g of μm silicone resin particles and compound (b)
) was used in the same manner as in Example 1, except that 24.0 g of carrier with a triboelectric charge control layer thickness of 0.91μ was used.
Manufactured.

Comparative example - has the same basic unit as compound (a) and has an average particle size of 3.2
18.0 g of μm silicone resin particles and a compound (
Using 72.0 g of b), the thickness of the triboelectric charge control layer was 3.
．． A carrier was manufactured in the same manner as in Example-1 except that the thickness was 0 μm.

Table 1 shows the film thicknesses of the carrier intermediate layer and triboelectric charge control layer and the average particle size of the silicone resin fine particles in the above Examples and Comparative Examples.

(Margin below) (Manufacture of toner) Styrene-methyl methacrylate-butyl methacrylate copolymer, (copolymerization ratio 50:20:30 molar ratio) 100 parts by weight, carbon black as Regal 660R (manufactured by Cabot) 10 parts by weight and 3 parts by weight of Viscol 4O-660P (manufactured by Sanyo Chemical Industries, Ltd.) as a low molecular weight polypropylene were mixed using a Henschel mixer, and mixed, pulverized, and classified.

Next, 0.8% by weight of hydrophobic silica fine particles (average particle size 12 nm) treated with ammonium salt-modified polysiloxane was added, and D5. =11 μm toner was obtained.

(Adjustment of Developer) A developer was prepared by mixing the carrier produced in the above Examples and Comparative Examples with the above toner particles so that the toner content was 4.0% by weight.

(Evaluation of developer) Among the carriers of the above Examples and Comparative Examples, Comparative Example-2
Developers using carriers other than
U-B 1x1550J (manufactured by Konica Corporation), the carrier of Comparative Example-2 was r U-B 1x507
A running experiment was conducted using 0 J (manufactured by Konica Corp.) under environmental conditions of a temperature of 30° C. and a relative humidity of 80%.

After the first sheet, 100,000 sheets, and 200,000 sheets, the toner triboelectric charge amount, upper layer coverage, and polishing specific resistance were examined.

Toner scattering was confirmed only after 200,000 copies.

Specifically, each experiment was conducted as follows.

Toner triboelectric charge amount: After an image for evaluation was actually photographed, the amount of toner triboelectric charge was determined by a conventional blow-off method from a developer sampled from the sleeve of a developing machine.

Upper layer coverage; 2. Approximately 15 cc of Og carrier is placed in a 20 cc sample tube and stirred for 20 minutes using a wave rotor. Next, while holding the carrier with a magnet, washing was repeated with methyl ethyl ketone to dissolve the intermediate layer and the triboelectric charge control layer. Furthermore, the carrier was dried on a hot plate, the amount of weight loss was determined, and the upper layer coverage was determined according to the following formula.

Apparent resistivity: 100 V was applied to a 1 cm carrier layer under the conditions of an electrode area of 1 d and a load of 1 kg, and the value was calculated from the current value flowing there. For the measurements, the manufactured carrier was used at the start of running, and after the start of running, the carrier from which the toner had been removed by blow-off was used.

The results are summarized in Table-2.

(Left below) Coverage rate a% of first intermediate layer Coverage rate ba=c% of upper layer triboelectric charge control layer As is clear from Table 2, the present invention contains silicone resin fine particles in the triboelectric charge control layer. With this carrier, the coverage does not decrease due to running, the toner triboelectric charge does not change, and the toner does not scatter.

However, as in Comparative Example-1, the triboelectric charge control layer does not contain silicone resin particles. With carriers made only of fluororesin, the coverage decreases due to running, the amount of triboelectric charge of toner changes, and toner scattering occurs.

As in Comparative Example 2, the toner using a silicone resin has a low toner triboelectric charging performance, so the amount of charge is extremely low. Therefore, fog is high and density is low. and,
The image was slightly reversed.

In addition, in the present invention, Examples-A, B and Comparative Examples-
As is clear from D, it is preferable that the average particle size of the silicone resin fine particles is smaller than the film thickness of the triboelectric charge control layer, and as is clear from Example-B and Comparative Example-D, the average particle size of the silicone resin fine particles is It is preferable that the diameter is 3 μm or less.

Furthermore, as is clear from Example-〇, if the average particle size of the silicone resin fine particles is 3 μm or less, even if the average particle size of the resin fine particles is larger than the resin coating layer, the electrostatic charge is at the limit of the practical use level. An image developer is obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of a modified dry coating apparatus. 11...Raw material input valve, 12...Raw material input chute, 1
3... Product discharge valve, 14... Product discharge chute, 1
5... Rotating disk, 16... Blade, 17... Stator, 18... Recycling piping, 19... Jacket, 20... Casing, 21... Thermometer.

Claims (3)

[Claims] (1) A carrier for electrostatic image development comprising an intermediate layer provided on a core material, which has a triboelectric charge control layer made of a resin that performs triboelectrification control on the intermediate layer, and the triboelectric charge control layer is made of silicone. A carrier for electrostatic image development characterized by containing fine resin particles. (2) The carrier for electrostatic image development according to claim 1, wherein the average particle diameter of the silicone resin fine particles is smaller than the thickness of the triboelectric charge control layer. (3) The average particle size of the silicone resin fine particles is 3 μm.
The carrier for electrostatic image development according to claim 1, characterized in that: