JP3226962B2 - Carrier for two-component developer and two-component developer containing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier for a dry two-component developer used in electrophotography, electrostatic printing and the like.
And a two-component developer containing the same .

[0002]

2. Description of the Related Art Conventionally, a so-called two-component dry developer comprising a mixture of carrier particles and toner particles is well known. In this two-component dry developer, fine toner particles are held on a relatively large particle surface by an electric force generated by friction between the two particles, and when the electrostatic latent image comes close to the electrostatic latent image, the electrostatic latent image is formed. The attraction force in the latent image direction on the toner particles due to the electric field to be formed overcomes the bonding force between the toner particles and the carrier particles, and the toner particles are attracted and adhered on the electrostatic latent image to visualize the electrostatic latent image. Things. The developer is used repeatedly while replenishing the toner consumed by the development.

[0003] Generally, metal oxides such as magnetite and ferrite are widely used as carrier materials for two-component developers, and have a smaller apparent density than iron powder carriers and the like and can be reduced in weight as a developer. Therefore, when the developer is stirred in the developing device, there is an advantage that the stirring resistance is reduced. Further, compared to the iron powder carrier, the magnetic powder has characteristics that the residual magnetic flux density is low, the coercive force is small, and as a result, the area of the hysteresis loop is small. The magnetite, ferrite, etc. are chemically stable for an oxide, ozone generated in the copying machine, chemical change does not occur easily due to NO _X, and the like.

However, such oxide carriers such as ferrite and magnetite also cause mechanical collisions such as collisions between developer particles due to high-speed development and multiple-sheet copying, or collisions between developer particles and a developing machine, or the like. There is a drawback that a toner film is formed on the carrier surface by the heat generated by the action, that is, so-called spent occurs, and the charging characteristics of the carrier are reduced with use time, and toner scattering, ground fogging and the like occur.

In order to prevent such spent,
Conventionally, a method of coating the surface of the core particles with various resins has been proposed. As a result, there is an advantage that the life of the developer can be extended. Sometimes it will not work as a developing electrode,
Particularly, it is difficult to obtain a uniform image, for example, an edge effect appears in a solid black portion. Therefore, as a technique for reducing the electric resistance of a coating carrier, a technique for containing conductive fine particles in a resin coating layer has been conventionally proposed.
(Japanese Unexamined Patent Publication (Kokai) No. 58-220245 and 57-4026.
However, in a coating carrier having a resin coating layer containing conductive fine particles, the conductive fine particles existing on the surface of the resin coat layer are easily detached. There are problems that the separated conductive fine particles adhere to the toner to deteriorate the triboelectric charging property of the toner and that the low surface energy characteristics are not sufficiently exhibited by the conductive fine particles present on the surface. As described above, if the triboelectric charging property of the coated carrier does not change or low surface energy characteristics are not exhibited, it becomes difficult to impart stable triboelectric charging to the toner as a result, and the coating carrier must be replaced early. Inconvenience occurs.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a carrier for a two-component developer having a stable triboelectric charging property. Another object is to provide a carrier for a two-component developer capable of preventing a decrease in charge amount when a copied image is formed for a long period of time and maintaining sufficient durability , and containing the carrier.
The object is to provide a two-component developer .

[0007]

In order to solve the above-mentioned problems, a structure of the present invention comprises an aminosilane coupling agent containing a primary and / or secondary amino group on the surface of a carrier core particle and a conductive polymer material. An internal resin layer and a surface resin layer covering the internal resin layer. The internal resin layer has a thickness L ₁ of 0.5 <L ₁ <1.0 and a thickness L ₂ of the surface resin layer.
Is 0.1 <L ₂ <0.5, wherein the surface resin layer is formed of a resin having a low surface energy. Carrier and Nisei containing it
Minute developer .

That is, according to the present invention, the resin coating layer has a two-layer structure of an inner layer and an outer layer, and in particular, the inner layer is selected and a conductive polymer material is contained therein, so that the surface of the resin coating layer has high conductivity. The conductive polymer material is prevented from being detached by not exposing the molecular material, and even if the conductive polymer material exists in the inner layer, the effect of reducing the electric resistance of the entire coating carrier is sufficiently obtained. It is confirmed that it is completed. Further, in the present invention, by particularly selecting the inner layer and dispersing the aminosilane coupling agent in the inner layer, it is possible to prevent a decrease in the charge amount when a copied image is formed for a long period of time and to maintain sufficient durability. Further, in the present invention, the thickness L of the inner layer
₁ (μm) is 0.5 <L ₁ <1.0, and the thickness L of the surface resin layer is
₂ (μm) is 0.1 <L ₂ <0.5. L ₁ <0.5 and 0.5 <L ₂ , or 1.0 <L
_{When 1} and 0.5 <L ₂ , an edge effect due to an increase in resistance occurs. On the other hand, when L ₂ <0.1, uniform coating with a coating becomes difficult, the inner layer containing the conductive fine particles is exposed, low surface energy characteristics are not sufficiently exhibited, and the change in triboelectric charging becomes remarkable.

The core material used for the carrier of the present invention may be a conventionally known material, for example, a ferromagnetic metal such as iron, cobalt and nickel; an alloy or a compound such as magnetite, hematite and ferrite; glass beads; Can be The average particle size of these core particles is usually 10 to 1000.
μm, preferably 30 to 500 μm.

As the coating resin for forming the internal resin layer of the carrier of the present invention, a conventionally known resin can be used as the carrier coating resin. Specifically, a styrene resin, an acrylic resin, a styrene-acryl copolymer resin, a vinyl resin, an ethylene resin, a rosin-modified resin, a polyamide resin, a polyester resin, or the like can be used. Among these, those having good adhesiveness with the magnetic particles are preferable from the viewpoint of increasing the film strength,
From the viewpoint of enhancing the dispersibility of the conductive polymer material, a material having high compatibility with the conductive polymer material is preferable. Specifically, a styrene resin such as a styrene-butadiene resin, a styrene-acrylic resin, an acrylic resin, or the like can be preferably used.

As the conductive polymer material contained in the inner layer, a highly anisotropic polymer material is doped,
A conductive material can be used. For example, the polymer doped with fluoride arsenic (AsF ₅₎ to a stretched polyacetylene, stretched polyacetylene iron chloride (Fe
Cl ₃₎ polymer doped with perchlorate ions polypyrrole (ClO ₄ ^-) can be mentioned doped polymer or the like. The content ratio of the conductive polymer material is particularly preferably from 5 to 30 parts by weight based on 100 parts by weight of the internal resin in view of the effect of reducing the electric resistance and the film strength. Is reduced.
On the other hand, if it exceeds 30 parts by weight, the mechanical strength becomes weak and the durability in long-term continuous use becomes insufficient.

The resin constituting the surface of the resin coat layer is preferably a resin having low surface energy characteristics from the viewpoint of effectively preventing the adhesion of the toner substance. In particular,
Polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-ethylene tetrafluoride copolymer, ethylene tetrafluoride / ethylene hexafluoride copolymer, polytetrafluoroethylene chloride, ethylene tetrafluoride / perfluoroalkyl A vinyl ether copolymer, a vinylidene fluoride-tetrafluoroethylene copolymer, a fluorinated resin having a group in which a fluorine atom is substituted in a side chain, a condensation-curable silicone resin, or the like can be used. Among the fluorine-containing resins, acrylic acid-1,1,3-trihydroperfluoro-
Preferred are n-propyl and 1,1-dihydroperfluoroethyl acrylate polymers.

As a method for forming a resin layer using the coating resin as described above, a resin solution in which a silane coupling agent and a surfactant are dispersed is applied by means of a spraying method, a dipping method or the like, as in the prior art. Similarly, only the resin solution may be applied.

In the present invention, the silane coupling agent dispersed in the internal resin layer is a compound represented by the formula X—Si (OR) ₃ , where X is a functional group that reacts with organic substances, and R is a hydrolyzate. A possible group. In particular, an aminosilane coupling agent having an amino group is desirable, and 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight is added to 100 parts by weight of the internal resin. If the amount is less than 0.5 part by weight, the effect of reducing the decrease in charge amount due to long-term copying cannot be sufficiently obtained. Conversely, if the amount exceeds 5 parts by weight, the risk of excessive increase in charge amount and color development The risk of exceeding the upper limit of the resistance value required to prevent the edge effect when used as a carrier is increased. Examples of the aminosilane coupling agent include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethylmethoxysilane, γ
-Aminopropyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride and the like.

Hereinafter, the present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.

The amounts (parts) of the components described in the examples are parts by weight.

Carrier Production Example 1 Composition of Internal Resin Layer Forming Solution Styrene-Acrylic Resin 60 parts Polymer (conductive polymer material, average particle diameter 1 μm) obtained by doping expanded polyacetylene with iron chloride (FeCl ₃ ) 2 parts Aminosilane Coupling agent [γ- (2-aminoethyl) aminopropyltrimethoxysilane] 4.0 parts Methyl ethyl ketone 300 parts The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was prepared by
An inner resin layer was formed by coating the surface of 5000 μm spherical ferrite with a fluidized bed coating device.

Composition of Surface Resin Layer Forming Solution Styrene-Acrylic Resin 20 parts Methyl ethyl ketone 100 parts Materials having the above composition were dispersed with a homomixer for 30 minutes to prepare a coating layer forming solution. The coating layer forming liquid was applied on the ferrite particles on which the internal resin layer was formed by using a fluidized bed type coating apparatus to form a surface resin layer and obtain carrier A.

Carrier Production Example 2 Composition of Internal Resin Layer Forming Solution Styrene-Acrylic Resin 60 parts Polymer (conductive polymer material, average particle size 1 μm) obtained by doping expanded polyacetylene with iron chloride (FeCl ₃ ) 2 parts Aminosilane Coupling agent [γ- (2-aminoethyl) aminopropyltrimethoxysilane] 0.2 parts Methyl ethyl ketone 300 parts The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was prepared by
It was applied to the surface of 5000 μm spherical ferrite using a fluidized bed coating apparatus to form an internal resin layer.

Composition of Surface Resin Layer Forming Liquid Polyvinylidene fluoride resin (low surface energy resin) 60 parts Methyl ethyl ketone 100 parts The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was applied on the ferrite particles on which the internal resin layer was formed by using a fluidized bed type coating apparatus to form a surface resin layer and obtain carrier B.

Carrier Production Example 3 Composition of Internal Resin Layer Forming Solution Styrene-Acrylic Resin 60 parts Polymer (conductive polymer material, average particle size 1 μm) obtained by doping polypyrrole with perchlorate ion (ClO ₄ ⁻ ) 10 parts Aminosilane coupling agent [γ- (2-aminoethyl) aminopropyltrimethoxysilane] 0.2 parts Methylethylketone 300 parts The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was prepared by
An inner resin layer was formed by coating the surface of 5000 μm spherical ferrite with a fluidized bed coating device.

Composition of Surface Resin Layer Forming Solution Styrene-Acrylic Resin 20 parts Methyl ethyl ketone 100 parts Materials having the above composition were dispersed with a homomixer for 30 minutes to prepare a coating layer forming solution. This coating layer forming liquid was applied onto the ferrite particles on which the internal resin layer was formed by using a fluidized bed type coating apparatus to form a surface resin layer and obtain carrier C.

Carrier Production Example 4 Composition of Internal Resin Layer Forming Solution Styrene-Acrylic Resin 60 parts Polymer (conductive polymer material, average particle diameter 1 μm) obtained by doping polypyrrole with perchlorate ion (ClO ₄ ⁻ ) 2 parts Aminosilane coupling agent [γ- (2-aminoethyl) aminopropyltrimethoxysilane] 1 part Methyl ethyl ketone 300 parts The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was prepared by
An inner resin layer was formed by coating the surface of 5000 μm spherical ferrite with a fluidized bed coating device.

Composition of Surface Resin Layer Forming Solution Styrene-Acrylic Resin 20 parts Methyl ethyl ketone 100 parts Materials having the above composition were dispersed with a homomixer for 30 minutes to prepare a coating layer forming solution. The coating layer forming liquid was applied to the ferrite particles on which the internal resin layer was formed by using a fluidized bed type coating apparatus to form a surface resin layer and obtain carrier D.

Carrier Production Example 5 Composition of Internal Resin Layer Forming Solution Styrene-Acrylic Resin 60 parts Polymer (conductive polymer material, average particle size 1 μm) obtained by doping polypyrrole with perchlorate ion (ClO ₄ ⁻ ) 10 parts Aminosilane coupling agent [γ- (2-aminoethyl) aminopropyltrimethoxysilane] 1.0 part Methyl ethyl ketone 300 parts The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was prepared by
An inner resin layer was formed by coating the surface of 5000 μm spherical ferrite with a fluidized bed coating device.

Composition of Surface Resin Layer Forming Liquid Polyvinylidene fluoride resin (low surface energy resin) 20 parts Methyl ethyl ketone 100 parts The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was applied onto the ferrite particles on which the internal resin layer was formed by using a fluidized bed type coating apparatus to form a surface resin layer, thereby obtaining a carrier E.

The thickness of the resin layers of the carriers A to E was 0.6 μm for the inner layer and 0.2 μm for the surface layer.

Comparative Example 1 for Carrier Production Composition of Resin Layer Forming Solution Styrene-Acrylic Resin 60 parts Polymer (conductive polymer material, average particle size 1 μm) obtained by doping expanded polyacetylene with iron chloride (FeCl ₃ ) 10 parts Aminosilane Coupling agent [γ- (2-aminoethyl) aminopropyltrimethoxysilane] 2 parts Methyl ethyl ketone 300 parts The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was prepared by
The surface of 5000 μm spherical ferrite was coated using a fluidized bed type coating apparatus to obtain a carrier F having a resin layer of 0.6 μm.

Carrier Production Comparative Example 2 Composition of Internal Resin Layer Forming Solution Styrene-Acrylic Resin 60 parts Polymer (conductive polymer material, average particle diameter 1 μm) obtained by doping expanded polyacetylene with iron chloride (FeCl ₃ ) 2 parts 300 parts of methyl ethyl ketone The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was prepared by
An inner resin layer was formed by coating the surface of 5000 μm spherical ferrite with a fluidized bed coating device.

Composition of Surface Resin Layer Forming Solution Styrene-Acrylic Resin 20 parts Methyl ethyl ketone 100 parts Materials having the above composition were dispersed with a homomixer for 30 minutes to prepare a coating layer forming solution. This coating layer forming liquid was applied on the ferrite particles on which the internal resin layer was formed by using a fluidized bed type coating apparatus to form a surface resin layer and obtain carrier G.

Carrier Production Comparative Example 3 Composition of Internal Resin Layer Forming Solution Styrene-Acrylic Resin 60 parts Aminosilane coupling agent [γ- (2-aminoethyl) aminopropyltrimethoxysilane] 1.0 part Methylethylketone 300 parts The raw materials were dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was prepared by
An inner resin layer was formed by coating the surface of 5000 μm spherical ferrite with a fluidized bed coating device.

Composition of Surface Resin Layer Forming Solution Styrene-Acrylic Resin 20 parts Methyl ethyl ketone 100 parts Materials having the above composition were dispersed with a homomixer for 30 minutes to prepare a coating layer forming solution. The coating layer forming liquid was applied on the ferrite particles on which the internal resin layer was formed by using a fluidized bed type coating apparatus to form a surface resin layer and obtain a carrier H.

Comparative Example 4 of Carrier Production Composition of Internal Resin Layer Forming Solution Styrene-Acrylic Resin 20 parts Polymer (conductive polymer material, average particle diameter 1 μm) obtained by doping expanded polyacetylene with iron chloride (FeCl ₃ ). Part Aminosilane coupling agent [γ- (2-aminoethyl) aminopropyltrimethoxysilane] 0.2 part Methylethylketone 100 parts The raw material having the above composition was dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. This coating layer forming liquid was prepared by
An inner resin layer was formed by coating the surface of 5000 μm spherical ferrite with a fluidized bed coating device.

Composition of Surface Resin Layer Forming Liquid Styrene-acrylic resin 60 parts Methyl ethyl ketone 300 parts The raw material having the above composition was dispersed for 30 minutes using a homomixer to prepare a coating layer forming liquid. This coating layer forming solution was applied on the ferrite particles on which the internal resin layer was formed by using a fluidized bed type coating apparatus to form a surface resin layer and obtain carrier I.

The thickness of the inner resin layer of the carriers G and H is 0.6 μm for the inner layer, and the thickness of the surface resin layer is 0.2 μm.
m. The thickness of the internal resin layer of I is 0.2 μm.
m, and the thickness of the surface resin layer was 0.6 μm.

Nine types of two-component developers were prepared by mixing 1000 parts of each of the obtained nine types of carriers with 35 parts of a commercially available polyester toner.

Next, each developer was set in a remodeled electrophotographic copying machine FT4060 manufactured by Ricoh Co., Ltd., and continuous copying was performed, and the edge effect and background fog of the copied image were examined. Table 1 shows the results. The evaluation of the edge effect was performed using a photographic chart and a developing potential of 300 to 400.
V, PG 0.7-0.8 mm, linear velocity ratio (Vs / Vp) =
Under the conditions of 1.5 to 3.5, not only a normal DC bias but also an AC bias was superimposed, and the level of white spots due to the edge effect at the boundary between the solid portion and the halftone portion of the copied image was evaluated. .

[0038]

[Table 1]

[0039]

The use of the carrier having the above structure prevents the conductive polymer material from being exposed on the surface, so that a change in triboelectric charging property is reduced and a desired resistance value is realized to achieve the edge effect. The result is a uniform, high-quality image without defects. Further, it is possible to prevent ground fogging due to a decrease in the amount of charge when a copied image is formed for a long time by using an aminosilane coupling agent in the internal resin layer, and to realize sufficient durability.

Continuation of front page (56) References JP-A-2-51167 (JP, A) JP-A-1-284862 (JP, A) JP-A-1-288865 (JP, A) JP-A-3-73967 (JP) JP-A-3-259157 (JP, A) JP-A-63-281173 (JP, A) JP-A-3-210569 (JP, A) JP-A-4-275560 (JP, A) 5-107816 (JP, A) JP-A-5-107817 (JP, A) JP-A-5-107818 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/113

Claims (3)

(57) [Claims] Claims: 1. A primary and / or secondary surface on a carrier core particle.
An internal resin layer containing an aminosilane coupling agent containing a secondary amino group, a conductive polymer material, and a surface resin layer covering the internal resin layer.
₁ (μm) is 0.5 <L ₁ <1.0, and the thickness L ₂ (μm) of the surface resin layer is 0.1 <L ₂ <0.5. . 2. The carrier for a two-component developer according to claim 1, wherein the surface resin layer is made of a resin having a low surface energy. 3. The carrier according to claim 1 or claim 2.
A two-component developer.