JP3771951B2 - Electrophotographic carrier and manufacturing method thereof, developing roll sleeve - Google Patents

Description

【００２９】
〔実施例３〕
ナイロン-12 （東レ社製、リルサンＡＭＮＯ） １０部
ケッチェンブラック（ライオンアクゾ社製、ＥＣ−ＤＪ５００） ２部
上記材料を２００℃に加熱したロールミルで２０分間混練し、冷却した。
上記混練物 １２部
スチレン・アクリロニトリル共重合体（共重合比７：３） ２０部
上記材料を２５０℃に加熱溶融して、富士ゼロックス社製レーザープリンター４１０５用現像ロールスリーブ（ステンレス製）表面に５０ｇ／ｍ² の厚さで被覆し、実施例３の帯電付与部材を得た。
得られた帯電付与部材の被覆層を透過型電子顕微鏡で観察すると、２種類の樹脂の界面を確認することができた。また、ナイロン-12 中にカボンブラックが分散していることが観察された。
【００３０】
〔比較例３〕
富士ゼロックス社製レーザープリンター４１０５用現像ロールスリーブ（ステンレス製）をそのまま使用した。
【００３１】
（トナー製造例２）
スチレン・ｎブチルアクリレート樹脂 ４４部
マグネタイト（戸田工業社製、ＥＰＴ−１０００） ５０部
帯電制御剤（保土谷化学社製、ＴＲＨ） ２部
ポリプロピレンワックス（三洋化成社製、６６０Ｐ） ４部
上記材料を用いて混練粉砕法で平均粒径７．５μｍのトナー粒子を得た。
上記トナー粒子１００部に、コロイダルシリカ（日本アエロシル社製、Ｒ９７２）０．８部を添加してヘンシェルミキサーで混合し、評価用トナーを得た。
【００３２】
（画質評価）
実施例３及び比較例３で得たスリーブを富士ゼロックス社製レーザープリンター４１０５に装着し、トナー製造例２のトナーを用いて画質評価を行った。結果は、表２に示した。実施例３の帯電付与部材は、比較例３に比べて、画質安定性が優れていた。
【００３３】
【表２】

【００３４】
【発明の効果】
本発明は、上記の構成を採用することにより、帯電維持性、環境安定性、画質維持性を大幅に向上させることができ、画像への濃度ムラや地汚れがなく、低電位潜像の再現性が良く、優れた画質を得ることができるようになった。[0001]
[Technical field to which the invention belongs]
The present invention relates to an electrostatic charge image developing carrier used when developing an electrostatic charge image formed by an electrophotographic method, an electrostatic recording method or the like with a two-component developer, a manufacturing method thereof, and a developing roll sleeve .
[0002]
[Prior art]
A method for visualizing image information through an electrostatic charge image such as electrophotography is currently used in various fields. In electrophotography, an electrostatic latent image is formed on a photoconductor in a charging and exposure process, the electrostatic latent image is developed with a developer containing toner, and visualized through a transfer and fixing process. The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer used alone such as a magnetic toner, but the two-component developer is a carrier in which the developer is stirred, conveyed, Since functions such as charging are shared and functions are separated as a developer, they are widely used for reasons such as good controllability.
[0003]
In particular, a developer using a resin-coated carrier has excellent charge controllability, and is relatively easy to improve environment dependency and stability over time. As a developing method, a cascade method has been used in the past, but at present, a magnetic brush method using a magnetic roll as a developer transport carrier is mainly used. Also in a developing method using a one-component developer, a charge imparting member such as a developing roll, a toner supply roll, or a charging blade is incorporated with a specific resin or a charge control agent to improve image quality and maintainability.
[0004]
In the magnetic brush method using a two-component developer, a decrease in image density due to developer charge deterioration, significant background stains, image roughness due to carrier adhesion to the image, carrier consumption, and image density There are problems such as unevenness. Further, due to charging deterioration of the developer, there is a tendency for background stains to occur when the environment changes such as humidity and temperature, or when toner is added or when the toner concentration is high.
[0005]
In order to speed up the rise of charge during development, eliminate the occurrence of carrier adhesion, and improve the reproducibility of halftones, it has been proposed to reduce the resistance of the carrier. For example, carbon black is added to the surface of magnetic particles coated with a silicone resin or the like to lower the resistance of the carrier (see JP-A-6-148952), a dispersion of fluoropolymer particles, a dispersion of carbon black, The mixture is coated with magnetic particles to prevent halftone reproducibility and carrier adhesion (see Japanese Patent Application Laid-Open No. 5-34993). It has been proposed to reduce the resistance (see JP-A-6-202382). However, when the electric resistance of the carrier is lowered by these methods, there is a problem that the charge amount is lowered and the image quality maintenance property is deteriorated.
[0006]
[Problems to be solved by the invention]
Accordingly, the present invention is intended to solve the above-described problems and provide an electrophotographic carrier having the following characteristics, a manufacturing method thereof, and an electrophotographic charging member.
(1) High image quality can be ensured even during long-term use.
(2) Improve background stains when adding toner and extend the life of the developer and the charge imparting member.
(3) Improve image quality maintenance against changes in chargeability due to environmental fluctuations.
(4) An image quality excellent in reproducing solid black and fine lines can be provided.
(5) A low potential latent image can be developed efficiently.
[0007]
[Means for Solving the Problems]
As a result of intensive studies on the resin-coated carrier and the chargeability-imparting member in which the conductive powder is dispersed, the present inventors have used at least two types of resins that are incompatible with each other, and the conductive powder is applied only to one of the resins. It was found that the above-mentioned problems can be solved by dispersing the resin and coating the resin with a core material to form a resin layer.
That is, the present invention uses two or more types of resins that are incompatible with each other as a resin layer covering the core material, and disperses the conductive powder in one of them, so that an effective conductive property can be obtained with a small amount of conductive powder. The resin layer that can form a path and does not disperse the conductive powder makes it possible to maintain chargeability and solve the problems of the invention.
That is, this invention consists of the following structures.
[0008]
(1) In an electrophotographic carrier formed by coating a resin on a core material, the resin is made of at least two types of resins that are incompatible with each other, and conductive powder is dispersed in one resin. An electrophotographic carrier characterized by the above.
[0009]
(2) A method for producing an electrophotographic carrier, comprising a step of dispersing conductive powder in a resin, and a step of coating the dispersion and a resin incompatible with the resin on a core material.
[0010]
(3) A developing roll sleeve in which a core is coated with a resin, wherein the resin is made of at least two types of resins that are incompatible with each other, and conductive powder is dispersed in one resin. A developing roll sleeve .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The coating resin used in the present invention is not particularly limited as long as it is a combination of incompatible resins, and any of thermoplastic and thermosetting resins can be used. Specifically, the following resins can be used.
Copolymers of vinyl-based fluorine-containing monomers such as vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, monochlorotrifluoroethylene, monochloroethylene, trifluoroethylene;
Styrenes such as styrene, chlorostyrene and methylstyrene;
Α-methylene aliphatic monocarboxylic acids such as methyl methacrylate, methyl acrylate, propyl acrylate, lauryl acrylate, methacrylic acid, acrylic acid, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate;
Nitrogen-containing acrylics such as dimethylaminoethyl methacrylate;
Nitriles such as acrylonitrile and methacrylonitrile;
Vinylpyridines such as 2-vinylpyridine and 4-vinylpyridine;
Vinyl ethers; vinyl ketones: olefins such as ethylene, propylene, butadiene;
Main chain nitrogen-containing resins such as polyamide, polyimide and melamine;
Silicones such as methyl silicon and methyl phenyl silicon;
Polyesters containing bisphenol, glycol, etc .;
These homopolymers or copolymers can be used.
[0012]
Preferred among the above are coating resins for charge control that do not disperse conductive powder, such as copolymers of styrene-containing vinyl monomers such as vinylidene fluoride homopolymer, methyl methacrylate homopolymer, acrylonitrile, dimethylaminoethyl methacrylate, and styrene. Is mentioned. Examples of the conductive powder dispersing resin include polyamide, melamine, polyimide, polyester, and the like having high polarity. The incompatibility can be easily confirmed by observing the cross section of the carrier with a transmission electron microscope (hereinafter referred to as TEM) and checking whether an interface exists in the coating resin. Further, the incompatible resin, SP value (solubility parameter) that away.
[0013]
As the core particles used in the present invention, those having a substantially spherical shape such as iron powder, ferrite particles and granulated magnetite are suitable. A normal average particle diameter is about 20 to 120 μm.
[0014]
The amount of coating resin is image quality, secondary obstacles (decrease in fluidity due to high coating amount, poor developer transport, carrier adhesion to the photoreceptor due to high charging, and generation of low resistance carrier due to low coating amount, In consideration of leakage to the photoreceptor, carrier scattering due to charge injection, etc.) and chargeability, the total amount of the carrier core particles is 0.1 to 10% by weight, preferably 0.5 to 7% by weight, more preferably A range of 1 to 6% by weight is suitable. The mixing ratio of the resin for dispersing the conductive powder is suitably in the range of 1 to 99% by weight, preferably 3 to 97% by weight, more preferably 5 to 95% by weight, based on the total amount of the coating resin. If the amount is less than 1% by weight, the conductive path cannot be formed reliably. If the amount exceeds 99% by weight, the conductive powder is dispersed throughout the coating layer, so that the charge amount is reduced.
[0015]
The conductive powder used in the present invention is not particularly limited as long as it is an inorganic fine particle exhibiting conductivity. Specifically, a metal oxide such as carbon black, various metal powders, titanium oxide, tin oxide, magnetite, and ferrite is used. It can be illustrated. Among these, carbon black is easy to disperse in a highly polar resin and is suitable for being selectively dispersed in one resin layer.
The conductive powder can be selectively dispersed in one resin layer even after coating on the core particle surface by dispersing it in the most polar resin of two or more incompatible resins. The
[0016]
The addition amount of the conductive powder is suitably in the range of 1 to 100 parts by weight, preferably 2 to 80 parts by weight, more preferably 5 to 60 parts by weight with respect to the total amount of the coating resin. When the addition amount is less than 1 part by weight, the conductivity cannot be exhibited, and when it exceeds 100 parts by weight, it is difficult to disperse the conductive powder.
[0017]
The method of carrier preparation present invention, after mixing the most highly polar coating resin and conductive powder, after mixing with other coating resins, mixed with karyoplast particles, heating under reduced pressure, kneaded to a solvent After volatilizing and coating the core particles, or without using a solvent, the coating resin and the core particles are mixed and then heated and kneaded to a temperature higher than the melting point of the coating resin to melt the coating resin. Cover body particles. Examples of the manufacturing apparatus used for coating include a heating kneader, a heating Henschel mixer, a UM mixer, and a planetary mixer.
[0018]
As a method for dispersing the conductive powder, when coating with a solvent solution, the conductive powder can be added to the resin solution for dispersing the conductive powder and dispersed by a ball mill, a sand mill or the like. When the resin is melt-coated, the conductive powder-dispersed resin and the conductive powder can be melt-kneaded with a roll mill, a bamber mixer, an extruder, a pressure kneader, or the like, and then pulverized and used as necessary.
[0019]
The carrier of the present invention is mixed with toner and used as a two-component developer. The toner is obtained by dispersing a colorant or the like in a binder resin. Examples of the binder resin used in the toner include styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl (meth) acrylate, Α-methylene aliphatic monocarboxylic acid esters such as (meth) ethyl acrylate, n-propyl (meth) acrylate, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate; (meth) acrylonitrile, etc. Vinyl nitriles; vinyl pyridines such as 2-vinyl pyridine and 4-vinyl pyridine; vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone: ethylene, Unsaturated hydrocarbons such as propylene, isoprene and butadiene, and A polymer of a monomer such as a halogenated unsaturated hydrocarbon such as chloroprene, a copolymer obtained by combining two or more of these monomers, a mixture thereof, Non-vinyl condensation resins such as rosin-modified phenol formalin resin, epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, and polyether resin, or a mixture of these with the above vinyl resins. .
[0020]
Examples of the colorant used in the toner include carbon black, nigrosine dye, aniline blue, calcoyl blue, chrome yellow, ultramarine blue, methylene blue, rose bengal, phthalocyanine blue, or a mixture thereof.
[0021]
Examples of the toner component other than the colorant include a charge control agent, an offset preventing agent, a fluidity improving agent, and the like, and may contain magnetic fine powder as necessary.
The toner preferably has a smaller particle diameter for high image quality, and a toner having an average particle diameter of 5 to 12 microns, preferably 5 to 10 microns is preferable.
[0022]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited by this. In the examples, “parts” means parts by weight.
[Example 1]
Nylon-12 (Toray Industries, Rilsan AMNO) 10 parts Ketjen Black (Lion Akzo, EC-DJ500) 2 parts The above materials were kneaded in a roll mill heated to 200 ° C. for 20 minutes and cooled.
Cu-Zn ferrite (manufactured by Powder Tech Co., Ltd., average particle size 50 μm) 1000 parts Kneaded product 12 parts Styrene / acrylonitrile copolymer (copolymerization ratio 7: 3) 20 parts 1L small kneader equipped with a heater The temperature of the heating medium was raised to 250 ° C., and the mixture was stirred and kneaded for 60 minutes, and then the heater was turned off and cooled for 1 hour while stirring. Then, the carrier of Example 1 was obtained by sieving with a 105 μm sieve.
When the coating layer of the obtained carrier was observed with a transmission electron microscope, the interface between the two types of resins could be confirmed. It was also observed that carbon black was dispersed in nylon-12.
[0023]
[Example 2]
Polyester composed of bisphenol A / ethylene oxide adduct and terephthalic acid (acid value 14) 20 parts Ketjen black (manufactured by Lion Akzo, EC-DJ500) 6 parts Toluene 174 parts In a ball mill using the above materials as stainless steel media Dispersed for 15 hours.
Cu-Zn ferrite (manufactured by Powder Tech Co., Ltd., average particle size 50 μm) 1000 parts Dispersion 150 parts Polymethylmethacrylate toluene solution (solid content 10% by weight) 150 parts Toluene 300 parts In a 1 L small kneader equipped with the above, the temperature of the heating medium was raised to 100 ° C. and stirred while heating under reduced pressure to remove the solvent. Then, the carrier of Example 2 was obtained by sieving with a 105 μm sieve.
When the coating layer of the obtained carrier was observed with a transmission electron microscope, the interface between the two types of resins could be confirmed. It was also observed that carbon black was dispersed in the polyester.
[0024]
[Comparative Example 1]
Cu-Zn ferrite (Powder Tech Co., average particle size 50μ) 1000 parts Nylon-12 (Toray Co., Rilsan AMNO) 10 parts Styrene-acrylonitrile copolymer (copolymerization ratio 7: 3) 20 parts Weight of the above materials The carrier of Comparative Example 1 was obtained in the same manner as in% 1.
[0025]
[Comparative Example 2]
200 parts of polymethyl methacrylate in toluene (solid content 10% by weight) Ketjen Black (Lion Akzo, EC-DJ500) 6 parts The above materials were dispersed for 15 hours in a ball mill using stainless steel balls as media.
Cu-Zn ferrite (manufactured by Powdertech Co., Ltd., average particle size 50 μm) 1000 parts Dispersion 154.5 parts Polymethylmethacrylate toluene solution (solid content 10% by weight) 150 parts Toluene 300 parts The carrier of Comparative Example 2 was obtained by processing in the same manner.
When the obtained coating layer of the carrier was observed with a transmission electron microscope, the interface of the resin could not be confirmed and was uniform.
[0026]
(Toner Production Example 1)
Styrene / n-butyl acrylate resin 87 parts carbon black (Cabot, BPL) 8 parts charge control agent (Hodogaya Chemical, TRH) 1 part polypropylene wax (Sanyo Chemicals, 660P) 4 parts Using the above materials Toner particles having an average particle size of 7.5 μm were obtained by a kneading and pulverization method.
To 100 parts of the toner particles, 1 part of colloidal silica (manufactured by Nippon Aerosil Co., Ltd., R972) was added and mixed with a Henschel mixer to obtain a toner for evaluation.
[0027]
(Image quality evaluation)
The carriers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were mixed with the toner of Toner Production Example 1 so as to have a toner concentration of 5% to prepare a developer for evaluation. Using these Able1301α modified machines manufactured by Fuji Xerox Co., Ltd., development conditions were set so that the developer had a dark potential of 400 V, an exposure portion potential of 100 V, and a development bias potential of 350 V, and image quality evaluation was performed. The results are shown in Table 1. The carriers of Examples 1 and 2 were superior to Comparative Examples 1 and 2 in charge retention and environmental stability, had good low-potential latent image developability, and were able to obtain good image quality.
[0028]
[Table 1]

[0029]
Example 3
Nylon-12 (Toray Industries, Rilsan AMNO) 10 parts Ketjen Black (Lion Akzo, EC-DJ500) 2 parts The above materials were kneaded in a roll mill heated to 200 ° C. for 20 minutes and cooled.
12 parts of the kneaded product styrene / acrylonitrile copolymer (copolymerization ratio 7: 3) 20 parts The above material is heated and melted to 250 ° C. and 50 g on the surface of the developing roll sleeve (stainless steel) for the laser printer 4105 manufactured by Fuji Xerox Co., Ltd. A charge imparting member of Example 3 was obtained by coating with a thickness of / m ² .
When the coating layer of the obtained charging member was observed with a transmission electron microscope, the interface between the two types of resins could be confirmed. It was also observed that the carbon black was dispersed in the nylon-12.
[0030]
[Comparative Example 3]
A developing roll sleeve (made of stainless steel) for laser printer 4105 manufactured by Fuji Xerox Co., Ltd. was used as it was.
[0031]
(Toner Production Example 2)
Styrene / n-butyl acrylate resin 44 parts magnetite (Toda Kogyo Co., EPT-1000) 50 parts charge control agent (Hodogaya Chemical Co., TRH) 2 parts polypropylene wax (Sanyo Kasei Co., Ltd., 660P) 4 parts Thus, toner particles having an average particle diameter of 7.5 μm were obtained by a kneading pulverization method.
To 100 parts of the toner particles, 0.8 parts of colloidal silica (manufactured by Nippon Aerosil Co., Ltd., R972) was added and mixed with a Henschel mixer to obtain a toner for evaluation.
[0032]
(Image quality evaluation)
The sleeves obtained in Example 3 and Comparative Example 3 were mounted on a laser printer 4105 manufactured by Fuji Xerox Co., Ltd., and image quality evaluation was performed using the toner of Toner Production Example 2. The results are shown in Table 2. The charge imparting member of Example 3 was superior in image quality stability as compared with Comparative Example 3.
[0033]
[Table 2]

[0034]
【The invention's effect】
By adopting the above-described configuration, the present invention can greatly improve the charge maintaining property, environmental stability, and image quality maintaining property, and there is no density unevenness or background smearing on the image and reproduction of a low potential latent image. The quality is good and it has become possible to obtain excellent image quality.

Claims (3)

  An electrophotographic carrier comprising a core coated with a resin, wherein the resin is composed of at least two types of resins that are incompatible with each other, and conductive powder is dispersed in one resin. A carrier for electrophotography.   A method for producing an electrophotographic carrier, comprising: a step of dispersing conductive powder in a resin; and a step of coating the dispersion and the resin incompatible with the resin on a core material. In developing roll sleeve formed by coating the resin on the core material, developing said resin is at least two resins are incompatible with each other, and conductive powder is characterized by being dispersed in one resin Roll sleeve .