JP3143545B2 - Electrophotographic charging member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member for electrophotography, and more particularly to a charging member for electrophotography having a resin layer containing a specific conductive resin.

[0002]

2. Description of the Related Art In a charging process in an electrophotographic process using an electrophotographic photosensitive member, charging is performed by a corona generated by applying a high voltage (DC 5 to 8 kV) to a metal wire in most cases. However, the corona products such as ozone and NO _x generated during charging in this way will by alteration of the photosensitive member surface, or causing the image blurring or deterioration, contamination of the wire affects the image quality, image There were problems such as white spots and black streaks. In addition, the electric current flowing toward the photoconductor is only 5 to 30% of the whole electric power, and most of the electric current flows to the shield plate, so that the charging means is inefficient.

In order to solve such disadvantages, for example, Japanese Patent Application Laid-Open No. 57-104351 and Japanese Patent Application Laid-Open No.
No. 67, JP-A-58-40566 and JP-A-58-139156 disclose a so-called direct charging method in which a photosensitive member is charged by applying a voltage to a charging member arranged in contact with the photosensitive member. Is disclosed. However, in practice, there is a problem that spot-like image defects caused by uneven charging and streak-like or band-like image defects caused by dielectric breakdown of the photoreceptor occur.

Therefore, for example, JP-A-64-66674 and JP-A-64-66676 propose to use a nylon resin as a surface layer of a charging member. Kaihei 2-51
Japanese Patent Publication No. 562 proposes to use a pyrrole-based conductive resin for the charging member, but these resin layers have not been sufficiently satisfactory in terms of environmental stability.

[0005] Also, Japanese Patent Application Laid-Open No. Sho 63-170673,
JP-A-2-198470 and JP-A-4-867
No. 64, etc. disclose a charging member having a resin layer containing a conductive additive, but these methods can provide a uniform conductivity without the conductive additive being uniformly dispersed. There was nothing.

On the other hand, in general, a method of molding a polyurethane raw material containing a conductive compound is disclosed in
18490 and JP-A-2-40683. As conductive compounds, carbon, metals, electrolyte salts, and the like are known, but in the case of metals, there is a problem that metal precipitates in the raw materials. There is a problem that the property is lost and handling is difficult.
Further, in the case of an electrolyte salt, there is a problem that the humidity dependence of conductivity is large. Further, it is known to improve the dispersibility of carbon by grafting various monomers to carbon ("Polymer" p. 823, Vol. 17, No. 198, 1).
968). However, even if an attempt is made to obtain a conductive resin by dispersing the carbon obtained by this method in a polyol and reacting it with a polyisocyanate compound, the flowability is insufficient and casting is difficult.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and in an environment from high temperature and high humidity to low temperature and low humidity, the surface of the photoreceptor can be remarkably discharged without causing discharge breakdown. Another object of the present invention is to provide a charging member for electrophotography, which can uniformly charge the toner, and can provide an extremely excellent image as a result.

[0008]

That is, the present invention relates to an electrophotographic charging member having a resin layer on a conductive support, wherein the resin layer comprises a monomer having an ethylenically unsaturated group, such as carbon and polyol. And a conductive polyurethane resin obtained by reacting a polymer mixture obtained by polymerizing in the presence of a polyisocyanate with a polyisocyanate.

According to the present invention, a monomer having an ethylenically unsaturated group is polymerized in the presence of carbon and a polyol. A homopolymer is generated, and a polyurethane resin having excellent conductivity can be easily obtained by reacting the polymer mixture containing a large amount of carbon with a polyisocyanate compound.

Further, in the present invention, since carbon is grafted with a monomer having an ethylenically unsaturated group, the compatibility between carbon and polyol is increased, and carbon is very uniformly dispersed in polyol. As a result, a conductive polyurethane resin containing carbon dispersed very uniformly can be obtained.

Furthermore, in the case of urethane resin in which carbon is simply dispersed in a polyol, the resistance greatly varies depending on the dispersion state and the amount of carbon added, so that it is difficult to stably produce a resin having a resistance in a specific region. On the other hand, in the present invention, since the dispersion state is uniform and stable, the resistance does not fluctuate abruptly even with the addition amount of carbon, so that a resin having a resistance in a specific region can be stably prepared. . FIG. 10 shows the dependence of the resistance value of the conductive polyurethane resin of the present invention and the polyurethane resin dispersedly containing untreated carbon on the amount of carbon added (○: present invention, Δ: untreated). The vertical axis in FIG. 10 is the volume resistivity (Ω · cm).
The horizontal axis indicates the amount (% by weight) of carbon (Ketjen black) added to the polyurethane resin. From this figure, it can be seen that the conductive polyurethane resin of the present invention has excellent resistance value stability.

In addition, since the conductive polyurethane resin of the present invention has a relatively high resistance of the resin itself, and the adjustment of the resistance largely depends on the conductivity of carbon, the conductive polyurethane resin has almost no hygroscopicity and has a low environmental stability. Is also excellent.

The monomers having an ethylenically unsaturated group used in the present invention include hydrocarbon monomers, unsaturated nitriles, vinyls, acrylic acid and its derivatives, and (meth) acrylates. Is mentioned. Preferred specific examples are shown below, but the present invention is not limited thereto.

Examples of the hydrocarbon monomers include styrenes [styrene and alkylstyrene (α-methylstyrene, o-, m- or p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p- n-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, etc.)]
And aliphatic hydrocarbon-based vinyls (such as butadiene).

Examples of the unsaturated nitriles include nitriles (acrylonitrile, methacrylonitrile, etc.).

Examples of vinyls include vinyl esters (such as vinyl acetate and vinyl propionate), vinyl ethers (such as vinyl methyl ether and vinyl ethyl ether), vinyl ketones (such as vinyl methyl ketone and vinyl hexyl ketone), and N-vinyl. (Such as N-vinylpyrrole, N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone) and vinyl halides (such as vinyl chloride).

Acrylic acid and its derivatives include:
(Meth) acrylic acid and (meth) acrylic acid ester ｛alkyl (meth) acrylate [methyl (meth) acrylate, butyl (meth) acrylate and trifluoroethyl (meth) acrylate, etc.], heterocyclic (meth) acrylate [tetrahydro Furfuryl (meth) acrylate, etc.], hydroxyalkyl (meth) acrylate [hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate, etc.], hydroxypolyoxyalkylene (oxyalkylene group preferably has 2 to 4 carbon atoms) (Meth) acrylates [such as hydroxypolyoxyethylene (meth) acrylate and hydroxypolyoxypropylene (meth) acrylate] and alkoxy (alkoxy groups preferably have 1 to 4 carbon atoms) The number of carbon atoms of the Le group is preferably 2
~ 3) (meth) acrylate [methoxyethyl (meth)
Acrylate and ethoxyethyl (meth) acrylate etc.] and amino group-containing (meth) acrylate [dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate etc.]}.

(Meth) acrylic acid salts include (meth)
Examples thereof include sodium acrylate, calcium (meth) acrylate, and zinc (meth) acrylate.

Among these, particularly preferred are hydrocarbon monomers, unsaturated nitriles, acrylic acid and its derivatives, and (meth) acrylates. When the carbon is basic, the monomer having an ethylenically unsaturated group is preferably acidic.

The monomers having an ethylenically unsaturated group may be used alone or in combination of two or more. If necessary, a monomer having two or more vinyl groups can be used in combination.

There is no particular limitation on the production method of the carbon, and carbon produced by the furnace method, channel method and thermal method, and natural products (such as graphite) can be used. Among them, acetylene black, which can easily form a structure, is preferable. The main performance items of carbon used in the present invention include DBP adsorption amount, specific surface area and volatile matter. The DBP adsorption amount (DBP ml / 100 g) is preferably from 40 to 500, and particularly preferably from 80 to 50.
It is preferably 0. In addition, the specific surface area (BETm ²
/ G) is preferably from 40 to 2,000, and particularly preferably from 45 to 1500. Further, the volatile content (% by weight) is preferably from 0.1 to 2.0, and particularly preferably from 0.1 to 1.0. The volatile content is a ratio of weight that decreases when carbon is heated at a high temperature (950 ° C.).

As the polyol used in the present invention, those usually used for polyurethane are used.
Examples include polyether polyols, polyester polyols, silicone glycols, polybutadiene glycols, castor oil, acrylic polyols, fluorine-containing polyols, polyol polymers, and mixtures thereof.

Examples of the polyether polyol include compounds having at least 2 (preferably 2 to 8) active hydrogen atoms (eg, polyhydric alcohols, polyhydric phenols, amines, polycarboxylic acids and phosphoric acids). And compounds having a structure in which an alkylene oxide is added thereto, and mixtures thereof.

Examples of the polyhydric alcohol include alkylene glycols such as ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol and neopentyl glycol; Dihydric alcohols such as diols (for example, those described in JP-B-45-1474); trihydric alcohols such as glycerin, trimethylolpropane, trimethylolethane, hexanetriol, and triethanolamine;
Tetrahydric alcohols such as pentaerythritol, methyl glycoside and diglycerin; sugar alcohols having more functional groups (eg pentitols such as adonitol, arabitol and xylitol, and hexitols such as sorbitol, mannitol, iditol, talitol and dulcitol); Sugars (eg, monosaccharides such as glucose, mannose, fructose and sorbose, and oligosaccharides such as sucrose, crehalose, lactose and raffinose); glycosides {eg, polyols (eg, glycols such as ethylene glycol and propylene glycol, glycerin, triglycerides) Glucosides of alkane polyols such as methylolpropane and hexanetriol; polyalkane polyols such as triglycerin and Dipentaerythritol and poly pentaerythritol tri pentaerythritol; polyglycerin such as fine tetraglycerol and cycloalkanes polyols include, for example, tetrakis (hydroxymethyl) cyclohexanol}.

Examples of the polyhydric phenol include monocyclic polyphenols such as pyrogallol, hydroquinone, and phloroglucin; bisphenols such as bisphenol A and bisphenol sulfone; and a condensate of phenol and formaldehyde (novolak) (see, for example, US Pat. No. 3,265,641). And polyphenols described in this document).

The amines include ammonia;
Alkanolamines such as mono-, di-, and tri-ethanolamine, isopropanolamine and aminoethylethanolamine; C1-C20 alkylamines; C2-C6 alkylenediamines [e.g., ethylenediamine, propylenediamine, hexamethylenediamine and polyamines]. Alkylene polyamines (for example, aliphatic amines such as diethylenetriamine and triethylenetetramine); aromatic amines such as aniline, phenylenediamine, diaminotoluene, xylylenediamine, methylenedianiline and diphenyletherdiamine; isophoronediamine, cyclohexyleneamine and Alicyclic amines such as dicyclohexyl methanediamine; aminoethylpiperazine and other JP-B-55-2104
Heterocyclic amines described in JP-A No. 4 (Kokai) No. 4 are cited.

These active hydrogen atom-containing compounds may be used in combination of two or more.

As the alkylene oxide to be added to the active hydrogen atom-containing compound, ethylene oxide,
Propylene oxide, 1,2-, 1,3-, 1,4
-, 2,3-butylene oxide, styrene oxide and the like, and a combination of two or more of these (block and / or
Or random addition).

As the polyester polyol,
"Polyurethane Resin Handbook" by Keiji Iwata, pages 108 to 111 of Nikkan Kogyo Shimbunsha, condensation type, lactone type and polycarbonate type.

Examples of the silicone glycol include a reactive silicone oil containing an active hydrogen in the molecule.

The polybutadiene glycol includes:
Pages 112 to 113 of the book.

Examples of the acrylic polyol include those described on page 112 of the book.

As the fluorine-containing polyol, 4,
4 '-(hexafluoroisopropylidene) -diphenol and 3-perfluorooctylpropanediol.

Examples of the polymer of the polyol include those obtained by polymerizing an ethylenically unsaturated monomer in a polyol in the presence of a polymerization initiator.

Preferred among these polyols are polyether polyols, polyester polyols and silicone glycols.

The OH value of the polyol used in the present invention is not particularly limited, but is preferably from 10 to 2,000, and particularly preferably from 20 to 1,000.

In the present invention, the monomer having an ethylenically unsaturated group: carbon: polyol (weight ratio) is (5
To 60) :( 5 to 100): 100, more preferably (5 to 30) :( 5 to 60): 100. Outside this range, the viscosity and conductivity of the composition may not be compatible at the same time.

The polymer mixture used in the present invention comprises:
It is obtained by graft-polymerizing a monomer having an ethylenically unsaturated group in the presence of carbon and a polyol. This graft polymerization is usually performed in the presence of a polymerization initiator. Examples of the polymerization initiator include an azo-based polymerization initiator and a peroxide-based polymerization initiator.

Specific examples of the azo polymerization initiator include:
2,2'-azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,
2'-azobis (2-methylbutyronitrile), 1,
1'-azobis (cyclohexane-1-carbonitrile), 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 1-[(1-cyano-1-methylethyl) azo] formamide (2- (carbamoyl Azo)
Isobutyronitrile, 2,2'-azobis (2,4,4
-Trimethylpentane) azodi-tert-octane), 2,2'-azobis (2-methylpropane) (azodi-tert-butane), dimethyl 2,2'-azobis (2-methylpropionate) and 2,2 '-Azobis [2- (hydroxymethyl) propionitrile and the like.

Examples of the peroxide-based polymerization initiator include diacyl peroxides such as isobutyryl peroxide, 2,4-dichlorobenzoyl peroxide and lauroyl peroxide; t-butylperoxy-neodecanoate and t-butylperoxy. -Alkyl peresters such as pivalate; bis (4-t-
Butylcyclohexyl) peroxydicarbonate, di-3-methoxybutylperoxydicarbonate, di-
Peroxides such as percarbonates such as 2-ethylhexylperoxydicarbonate and di-sec-butylperoxydicarbonate; and JP-A-61-765.
Peroxides other than those described in JP-A-17 are mentioned.

The amount of the azo polymerization initiator to be added is 0.01 to 100 parts by weight of the monomer having an ethylenically unsaturated group.
To 5 parts by weight, particularly 0.05 to 2 parts by weight.
Parts by weight, more preferably 0.1 to
1 part by weight.

The amount of the peroxide-based polymerization initiator added is
The amount is preferably 0.01 to 3 parts by weight, particularly preferably 0.05 to 2 parts by weight, more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the monomer having an ethylenically unsaturated group. １．５1.5 parts by weight.

The method for producing the polymer mixture used in the present invention is not particularly limited, and it can be produced by a method of performing batch polymerization in a batch system, a method of performing graft polymerization in a continuous reaction apparatus, or the like. In the present invention, a continuous method in which graft polymerization is carried out in a continuous reaction apparatus is preferable, since the viscosity of the obtained polymer mixture can be reduced. In the continuous method, a reaction vessel equipped with a stirrer or a mixing / extruder (Brabender, static mixer, kneader, Banbury mixer, etc.) capable of continuous polymerization can be used as a graft polymerization apparatus. The polymerization method is not particularly limited. For example, a polymerization catalyst, a monomer having an ethylenically unsaturated group, carbon and a polyol are preliminarily mixed, and 60 to 1
The reaction is carried out at 50 ° C. with a residence time of 0.5 to 10 hours. If necessary, a monomer having an ethylenically unsaturated group or a polymerization catalyst may be polymerized by dividing it. Further, unreacted monomers may be removed under reduced pressure.

Examples of the polyisocyanate used in the present invention include polyisocyanates and derivatives thereof (prepolymers having terminal NCO) described in "Polyurethane Resin Handbook" by Keiji Iwata, pages 71-82 of Nikkan Kogyo Shimbun. Among them, tolylene diisocyanate, metaphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, derivatives of these diisocyanates, and terminal NCOs of these and polyols
Are preferred. The NCO% (% by weight of isocyanate groups present in the sample) is preferably from 5 to 48, and particularly preferably from 7 to 35.

In the present invention, an electron conductor and an ionic conductor may be added as necessary. Examples of preferred electron conductors include graphite, metals (such as copper, aluminum, nickel and silver) and conductive polymers (such as polyaniline, polypyrrole, polythiophene, polyacetylene, polypyridine, polyacene, polyazulene, polydiphenylbenzidine, polyvinylcarbazole, and the like). And poly-3-alkylthiophene). Of these, metals, polyaniline, polypyrrole and polythiophene are particularly preferred. Examples of preferred ionic conductors include metal salts and ammonium salts. Examples of the metal salt include salts of metals of Group I or Group II. Among them, Li, Na having a relatively small cation radius are used.
And salts of K are particularly preferred. As anions constituting these metal salts, halogen ions (F, Cl, B
r and I), thiocyanate ion, perchlorate ion, trifluoromethanesulfonate ion, fluoroborate ion and the like. Among these, particularly preferred are thiocyanate ion, perchlorate ion,
Trifluoromethanesulfonate ion and fluoroborate ion. Also, as the ammonium salt,
Examples include ammonium salts of acids such as carboxylic acids (such as adipic acid, phthalic acid, azelaic acid), phosphoric acid, boric acid, sulfonic acids (such as arylsulfonic acids) and borofluoric acid. Of these ammonium salts, ammonium carboxylate, ammonium phosphate and ammonium borate are particularly preferred. The electron conductor and the ionic conductor may be used as a mixture. These are usually mixed with the polyol.

The conductive polyurethane resin of the present invention is not limited to foams and non-foams, and may be obtained by mixing a monomer having an ethylenically unsaturated group with a polyisocyanate, if necessary, with a catalyst, a foaming agent and a foam stabilizer. By reacting in the presence of As a catalyst, "Polyurethane Resin Handbook" by Keiji Iwata, Nikkan Kogyo Shimbun, p. 118-1
The organic metal catalyst and the amine catalyst described on page 22 are exemplified. Examples of the foaming agent include water and physical foaming agents (such as methylene chloride) described on page 125 of the book. As a foam stabilizer, a stabilizer (polysiloxane-polyoxyalkylene block copolymer, etc.) described on page 124 of the book is used
Is mentioned.

The charging member of the present invention has a layer containing at least a resin on a conductive support. Examples of the structure are shown in FIGS. 1 to 6. In the case of the so-called contact charging in which the charging member and the photoconductor are in contact, a roller shape as shown in FIGS. 1 and 2 and a blade shape as shown in FIG. 3 are exemplified. More preferably, there is. Further, the distance between the charging member and the photoconductor is 1000
In the case of so-called non-contact-proximity charging, which is close to, but not in contact with, about 500 μm or less, and preferably about 500 μm or less, a concentric circle with the photoreceptor as shown in FIG. Although various shapes such as an arc shape as shown in FIG. 6 and a plate shape as shown in FIG. 6 can be adopted, a concentric or arc shape is particularly preferable among them. In each figure,
1 is a conductive support, 2 is an elastic layer, 3 is a conductive layer, and 4 is a resistance layer.

When the charging member of the present invention has a multilayer structure, the polyurethane resin of the present invention can be used for any of the layers.

As the conductive support, aluminum,
Metals and alloys such as iron, copper and stainless steel, conductive resins and the like dispersed carbon and metal particles and the like can be used,
Examples of the shape include a rod shape and a plate shape as described above.

The elastic layer contains the conductive polyurethane resin of the present invention or another rubber or resin. When the conductive polyurethane resin of the present invention is used, the above-mentioned other rubbers and other resins may be further added and mixed as long as the characteristics of the present invention are not impaired.

The rubber includes styrene-butadiene rubber, high styrene rubber, butadiene rubber, isoprene rubber, ethylene-propylene copolymer, nitrile butadiene rubber, chloroprene rubber, butyl rubber, silicon rubber, fluorine rubber, nitrile rubber, acrylic rubber , Epichlorohydrin rubber and norbornene rubber. Examples of the resins include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, and styrene. -Vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer) Styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene- Butyl methacrylate copolymer and styrene Styrene-based resins such as phenyl acrylate copolymer, styrene-α-methyl methyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer (a homopolymer or copolymer containing styrene or a styrene substituent) Unified), vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic resin, phenol resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, Examples include an ethylene-ethyl acrylate copolymer, a xylene resin, and a polyvinyl butyral resin.

The film thickness is preferably 1.5 mm or more, more preferably 2 mm or more, and particularly preferably 3 mm to 13 mm.

The conductive layer is a layer having a high electric conductivity, and has a volume resistivity of 10 ⁷ Ω · cm or less, and more preferably 10 ⁶ Ω · cm.
Hereinafter, it is particularly preferable that the resistivity is 10 ⁻² to 10 ⁶ Ω · cm. Further, the thickness of the conductive layer is preferably a thin layer for transmitting the flexibility of the lower elastic layer to the upper layer such as the resistance layer or to the surface of the photoreceptor, specifically 3 mm or less, more preferably 2 mm or less. In particular, it is preferably 20 μm to 1 mm.

Examples of the material used include, in addition to the above-mentioned conductive polyurethane resin of the present invention, a metal-deposited film, a conductive particle-dispersed resin, and a conductive resin. Specifically, as the metal deposition film, aluminum, indium,
Nickel, copper and metal such as iron are vapor-deposited, and as the conductive particle-dispersed resin, conductive particles such as carbon, aluminum, nickel, and titanium oxide are converted to urethane, polyester, vinyl acetate-vinyl chloride copolymer. And a resin dispersed in a resin such as polymethyl methacrylate. Examples of the conductive resin include quaternary ammonium salt-containing polymethyl methacrylate, polyvinylaniline, polyvinylpyrrole, polydiacetylene, and polyethyleneimine. Among these, a conductive particle-dispersed resin is preferred from the viewpoint of controlling the conductivity.

The resistance layer is formed so as to have a higher resistance than the underlying conductive layer, and has a volume resistivity that is one to six digits, especially two to five digits, greater than the volume resistivity of the conductive layer. It is preferably an order of magnitude higher, with a range of 10 ⁶ to 10 ¹² Ω · c
m, particularly preferably 10 ⁷ to 10 ¹¹ Ω · cm. The thickness of the resistive layer is 1 μm to 50 μm from the viewpoint of chargeability.
0 μm, particularly preferably 50 μm to 200 μm.

Examples of the material used include, in addition to the conductive polyurethane resin of the present invention, a semiconductive resin, a conductive particle dispersed resin, and the like. Specific examples of the semiconductive resin include resins such as ethyl cellulose, nitrocellulose, methoxymethylated nylon, ethoxymethylated nylon, copolymerized nylon, polyvinylpyrrolidone and casein, and mixtures of these resins. As the particle-dispersed resin, carbon, aluminum, conductive particles such as indium oxide and titanium oxide are contained in the above-mentioned semiconductive resin or urethane, polyester, an insulating resin such as a vinyl acetate-vinyl chloride copolymer and polymethacrylic acid. ,
Examples thereof include those in which the resistance is adjusted by dispersing a small amount.

In the present invention, an adhesive layer can be provided between each layer in order to form a two-layer resistive layer or to improve the adhesiveness of each of the above-mentioned layers.

Regardless of the constitution, the volume resistivity of the charging member of the present invention is preferably from 10 ² to 10 ¹⁰ Ω · cm, particularly preferably from 10 ⁴ to 10 ⁸ Ω · cm. . Further, at least the volume resistivity of the surface layer is preferably within these ranges.

When the charging member of the present invention is used, if the surface of the charging member is rough, regardless of whether the charging member and the photoreceptor are in contact or non-contact, the unevenness of the charging member causes slight charging unevenness. Failure may occur.
Therefore, it is preferable that the surface of the charging member is smoother,
The 10-point average roughness _Rz in the standard of JIS B0601 surface roughness is 5 μm or less, and the maximum height _Rmax is 10 or less.
μm or less, particularly preferably R _z is 2 μm or less, and R _max is 5 μm or less.

When the charging member is used in contact with the photoreceptor, the charging member is deformed (compression set) due to long contact with the photoreceptor, thereby distorting the discharge area where charging is performed. Since a difference occurs between a portion and a portion other than the portion, a difference occurs in charging, and as a result, an image defect may occur. Therefore, in the present invention, it is preferable that the compression set is 40% or less as measured after standing at 70 ° C. for 22 hours in a state of a compressibility of 25% according to JIS K6301 and further standing at room temperature for 30 minutes. In particular, it is preferably at most 30%.

Further, when the charging member is used in contact with the photoreceptor, if the surface hardness of the charging member is too high, contaminants such as toner on the photoreceptor are rubbed and beaten by the charging member. For example, the toner may be melted on the photoconductor due to mechanical factors such as the above-described process, that is, an image defect due to so-called fusion may occur. In particular, when the applied voltage is the AC superimposed bias, the above-described phenomenon is more likely to occur than when the DC voltage is applied because the charging member vibrates due to the AC voltage.

Therefore, in the present invention, the surface hardness of the charging member is 50 in A hardness specified in JIS K6301.
° or less, and particularly preferably 35 °.

In addition, when the applied voltage is an AC superimposed bias, the “charging noise” is generated by the vibration of the charging member due to the AC voltage.
In some cases, the sound may be uncomfortable to humans, and the hardness may be 10 ° or less in consideration of reducing the hardness of the charging member to absorb vibration and reduce charging noise. preferable.

The charging member of the present invention is manufactured, for example, as follows.

First, a metal rod is prepared as a conductive support for the charging member. An elastic layer is provided by molding the conductive urethane resin of the present invention on a metal rod by melt molding, injection molding, dip coating or spray coating.

Next, the conductive layer is formed by molding the material of the conductive layer on the elastic layer by melt molding, injection molding, dip coating or spray coating.

Finally, the resistance layer is provided by dip coating, spray coating, gravure coating, or the like on the conductive layer to coat the material for the resistance layer.

The charging member of the present invention can be used for any of primary charging, transfer charging and static elimination charging as described below. Of course, they may be used simultaneously.

The charging member of the present invention can be applied to, for example, an electrophotographic apparatus as shown in FIG. This device includes a charging member for primary charging (a charging member of the present invention) 5, an image exposure unit 6, a developing unit 7,
A transfer charging corona charger 8, a cleaning means 9, and a pre-exposure means 10 are provided.

An external voltage (for example, 20) is applied to the primary charging charging member 5 which is arranged in contact with the electrophotographic photosensitive member 11.
DC voltage between 0 V and 2000 V and peak-to-peak voltage 40
A pulsating voltage on which an AC voltage of 00 V or less is superimposed,
The surface of the electrophotographic photosensitive member 11 is charged, and an image on a document is image-exposed on the photosensitive member by the image exposure means 6 to form an electrostatic latent image. Next, the electrostatic latent image on the photoconductor is developed (visualized) by attaching the developer in the developing unit 7 to the photoconductor,
Further, the developer on the photoreceptor is transferred to the transfer member 12 such as paper by the transfer charging unit 8, and the developer remaining on the photoreceptor without being transferred to the paper at the time of transfer by the cleaning unit 11 is collected.

An image can be formed by such an electrophotographic process. However, if residual charge remains on the photoconductor, light is applied to the photoconductor by the pre-exposure means 10 before primary charging. It is better to remove the charge.

When the charging member of the present invention is used for transfer charging, it can be applied to, for example, an electrophotographic apparatus as shown in FIG. The apparatus includes a primary charging corona charger 13, an image exposure unit 6, a developing unit 7, a transfer charging member (a charging member of the present invention) 14 on a peripheral surface of an electrophotographic photosensitive member 11,
Cleaning means 9 and pre-exposure means 10 are arranged.

A voltage (for example, a DC voltage of 40) is applied to the charging member 14 for transfer charging, which is disposed in contact with the electrophotographic photosensitive member 11.
0 to 1000 V) to transfer the developer on the electrophotographic photosensitive member to a member to be transferred such as paper. When the charging member of the present invention is used for static elimination charging, it can be applied to, for example, an electrophotographic apparatus as shown in FIG. In this apparatus, a primary charging corona charger 13, an image exposure unit 6, a developing unit 7, a transfer charging corona charger 8, and a cleaning unit 9 are arranged on a peripheral surface of an electrophotographic photosensitive member 11.

A voltage (for example, an AC peak-to-peak voltage of 500 to 2,000 V) is applied to a charging member for static elimination charging (the charging member of the present invention) 15 which is arranged in contact with the electrophotographic photosensitive member 11 to charge the charge on the electrophotographic photosensitive member. Can be neutralized.

The installation of the charging member to be brought into contact with the photoreceptor in the present invention is not limited to a specific method, and the charging member may be fixed or moved in the same direction as the photoreceptor or rotated in the opposite direction. A method can also be used. Further, it is also possible for the charging member to function as a developer cleaning device on the photosensitive member.

The voltage applied to the charging member and the method of application in the direct charging of the present invention depend on the specifications of each electrophotographic apparatus. A method of increasing the applied voltage stepwise for the purpose of protection, or a method of applying a voltage in the order of DC → AC or AC → DC when applying in the form of superimposing AC on DC can be adopted.

When the charging member of the present invention is used for primary charging of an electrophotographic apparatus, it is possible to superimpose a DC voltage and an AC voltage on an electrophotographic photosensitive member in an image output area, or to apply only a DC voltage. It is. When used for transfer charging,
The DC voltage alone or the DC voltage and the AC voltage may be superimposed.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

[0079]

【Example】

Example 1 8 parts by weight of styrene, 8 parts by weight of Ketjen black and polypropylene glycol (weight average molecular weight 5,000
0) 100 parts by weight were mixed, and 0.2 parts by weight of 2,2'-azobisisobutyronitrile was further added to obtain a polymer mixture. In a vacuum, 18 parts by weight of 2,4-toluene diisocyanate was added to the mixture, and the defoamed mixture was poured into a roller-shaped mold and heated at 80 ° C. for 3 hours to form a conductive support (aluminum having a diameter of 6 mm). A conductive polyurethane resin layer of the present invention having a thickness of 12 mm was formed on the rod) to prepare a roller-shaped charging member.

The volume resistivity of the obtained charging member was measured by wrapping an aluminum foil in close contact with the outer periphery of the charging member, applying a DC voltage (250 V) between the support and the aluminum foil, and applying a DC voltage (250 V) to a tester (HIOKI 3116 DEGIAL MΩ HI).
TESTER). Table 1 shows the results.

Also, a copying machine (FC-2, FC-2, NP6030 (manufactured by Canon Inc.)) equipped with a charging member obtained as charging means for primary charging and a photoconductor of NP6030 (manufactured by Canon Inc.) as a photoconductor.
Using a Canon Co., Ltd.), a DC voltage of -1500 V is applied to perform image output.
The image was evaluated by visually observing an image defect caused by uneven charging due to resistance unevenness of the charging member. Table 1 shows the results. In the table, ◎ indicates that the obtained image was excellent, ○ indicates that it was good, Δ indicates that it was practical, and X indicates that it was not practical.

Further, the photosensitive member of the above-mentioned copying machine was replaced with one photosensitive layer.
mm ^{2 was} peeled off to obtain a defective photoreceptor exposing the aluminum drum, an image was displayed at an applied voltage of −1800 V, and the pressure resistance was evaluated by observing image whitening caused by dielectric breakdown. Table 1 shows the results.
In the table, ◎ is excellent (white spots are only defective portions of the photoreceptor),
は is good (white drop is within 15 mm in the longitudinal direction of the photoreceptor from the defective portion of the photoreceptor), Δ is practical (white drop is more than 15 mm and less than 30 mm in the longitudinal direction of the photoreceptor), and x is not practical (white drop out) Exceeds 30 mm in the longitudinal direction of the photoreceptor).

The above volume resistivity, image and pressure resistance were evaluated at 32 ° C., 85% RH (environment 1) and 10%.
C., 5% RH (environment 2).

Further, using the above copying machine, a superimposed voltage (AC: peak-to-peak voltage 1.9 kV, 450 Hz, DC: -7
00V) was applied to form an image, and the charging noise generated at that time was evaluated. Table 1 shows the results. In the table, ◎ is excellent (no charging noise is heard at all), ○ is good (the charging noise is hardly heard), △ is practical (the charging noise is hidden by noise of other machines), and × is practical Indicates that it is not possible (a harsh sound is heard).

The cartridge of the above copying machine is
After leaving for 1 month in an environment of 85 ° C. and 85% RH, the apparatus is mounted on a copying machine main body, an image is output by applying a DC voltage of −1500 V, and an image defect caused by distortion of the charging member is observed. The strain resistance was evaluated. Table 1 shows the results. In the table, ◎ indicates excellent (no image defects), ○ indicates good (slightly streaks occurred in halftone image), Δ indicates practical use (slightly slight streaks), and X indicates no practical use (streaks occurred). Is shown.

Further, the obtained charging member was mounted as a primary charging means of a laser beam printer (Laser Jet Si, manufactured by Hewlett-Packard) at 32 ° C. and 85 ° C.
Under a% RH environment, a 10,000-image endurance test was performed to evaluate the state of fusion after endurance. Table 1 shows the results. In the table, ◎ indicates excellent (no fusion), は indicates good (observed on the photoreceptor, but does not appear in the image), △ indicates practical use (slightly generated in the image), and × indicates practical use (image (Occurs on the entire surface).

Further, the surface roughness (R _z ), compression set and hardness of the obtained charging member were measured by the methods described above. Table 2 shows the results.

Example 2 A charging member was prepared and evaluated in the same manner as in Example 1 except that Ketjen black and styrene were used in an amount of 13 parts by weight. The results are shown in Tables 1 and 2.

Example 3 A charging member was prepared and evaluated in the same manner as in Example 1 except that Ketjen black and styrene were changed to 5 parts by weight. The results are shown in Tables 1 and 2.

Example 4 A charging member was prepared and evaluated in the same manner as in Example 1 except that 30 parts by weight of acetylene black and styrene were used without using Ketjen black. Table 1 shows the results
And Table 2.

Example 5 The surface of the charging member obtained in Example 1 was sanded (# 10
A charging member was prepared and evaluated in the same manner as in Example 1 except that the surface was mechanically roughened by rubbing in step 0). The results are shown in Tables 1 and 2.

Example 6 A charging member was prepared and evaluated in the same manner as in Example 1 except that the surface of the charging member obtained in Example 1 was polished to mechanically smooth the surface. . The results are shown in Tables 1 and 2.

Example 7 A charging member was prepared and evaluated in the same manner as in Example 1 except that the number average molecular weight of polypropylene glycol was changed to 1,000. The results are shown in Tables 1 and 2.

Example 8 A charging member was prepared and evaluated in the same manner as in Example 1 except that the polypropylene glycol was changed to polyethylene glycol and the number average molecular weight was changed to 1,000. The results are shown in Tables 1 and 2.

Example 9 A polyurethane resin (Nipporan 2302, manufactured by Nippon Polyurethane) was applied on the surface of the charging member obtained in Example 1.
A solution in which 100 parts by weight of titanium oxide was dispersed in parts by weight using a sand mill was applied by dip coating, and dried to form a surface layer having a thickness of 10 μm.

The obtained charging member was evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Example 10 A solution in which 60 parts by weight of N-methoxymethylated nylon and 60 parts by weight of titanium oxide were dispersed using a sand mill was applied to the surface of the charging member obtained in Example 1 by dip coating. By drying, a surface layer having a thickness of 10 μm was formed.

The obtained charging member was evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Example 11 Ketjen black and styrene were adjusted to 10 parts by weight,
0.8 part by weight of a silicone foam stabilizer (SRX-274) was added, and the mixture was poured into a mold and foamed to obtain a cell diameter of 300 μm.
A charging member was prepared and evaluated in the same manner as in Example 1 except that the conductive urethane resin layer of the present invention was formed. The results are shown in Tables 1 and 2.

Example 12 A polyurethane resin (Nipporan 2302, manufactured by Nippon Polyurethane) was applied on the surface of the charging member obtained in Example 11.
A solution in which 35 parts by weight of titanium oxide was dispersed in 0 part by weight using a sand mill was applied by dip coating, and dried to form a surface layer having a thickness of 80 μm.

The obtained charging member was evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Example 13 A 12 mm thick Ketjen black-containing SBR rubber layer was formed on the conductive support used in Example 1. On this layer, a surface layer having a thickness of 20 μm was formed using the same solution for the conductive polyurethane resin layer of the present invention as in Example 1.

The obtained charging member was evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Example 14 A polyurethane resin (Nipporan 2302, manufactured by Nippon Polyurethane) was coated on the surface of the charging member obtained in Example 13.
A solution in which 100 parts by weight of titanium oxide was dispersed in 0 part by weight using a sand mill was applied by dip coating, and dried to form a surface layer having a thickness of 15 μm.

The obtained charging member was evaluated in the same manner as in Example 13. Table 1 shows the results.

Example 15 A non-contact / proximity charging member as shown in FIG. 4 was prepared using the same solution for the conductive polyurethane resin of the present invention as in Example 1.

The obtained charging member was evaluated in the same manner as in Example 1. At this time, the distance between the charging member and the photoconductor is 5
It was set to 0 μm. The results are shown in Tables 1 and 2.

Example 16 A charging member was prepared and evaluated in the same manner as in Example 1 except that hexamethylene diisocyanate was used instead of 2,4-toluene diisocyanate. The results are shown in Table 1 and Table 2.

Example 17 A charging member was prepared and evaluated in the same manner as in Example 1 except that 2,4-toluene diisocyanate was changed to 1,5-naphthalenediisocyanate. The results are shown in Tables 1 and 2.

Example 18 A charging member was prepared and evaluated in the same manner as in Example 15 except that hexamethylene diisocyanate was used instead of 2,4-toluene diisocyanate. The results are shown in Tables 1 and 2.

Example 19 A charging member was prepared and evaluated in the same manner as in Example 15 except that 1,4-naphthalenediisocyanate was used instead of 2,4-toluene diisocyanate. Tables 1 and 2 show the results.
Shown in

Comparative Example 1 A charging member was prepared and evaluated in the same manner as in Example 1 except that styrene was not used and Ketjen Black was 3 parts by weight. The results are shown in Tables 1 and 2.

Comparative Example 2 A charging member was prepared and evaluated in the same manner as in Comparative Example 1 except that Ketjen Black was used in an amount of 5 parts by weight. The results are shown in Tables 1 and 2.

Comparative Example 3 A charging member was prepared and evaluated in the same manner as in Comparative Example 1 except that Ketjen Black was changed to 1 part by weight. The results are shown in Tables 1 and 2.

Comparative Example 4 A charging member was prepared and evaluated in the same manner as in Example 1 except that styrene and Ketjen black were not used.
The results are shown in Tables 1 and 2.

Comparative Example 5 A charging member was prepared and evaluated in the same manner as in Example 13 except that the surface layer was not formed. The results are shown in Tables 1 and 2.

[0117]

[Table 1]

[0118]

[Table 2]

[0119]

As described above, according to the present invention, the photoconductor has stable conductivity in an environment from high temperature and high humidity to low temperature and low humidity, and does not cause discharge breakdown of the photoconductor. It is possible to provide an electrophotographic charging member which can be charged very uniformly and, as a result, can supply an extremely excellent image.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a layer configuration of a charging member of the present invention used in a contact charging method.

FIG. 2 is a diagram illustrating an example of a layer configuration of a charging member of the present invention used in a contact charging method.

FIG. 3 is a diagram illustrating an example of a layer configuration of a charging member of the present invention used in a contact charging method.

FIG. 4 is a diagram illustrating an example of a layer configuration of a charging member of the present invention used in a non-contact charging method.

FIG. 5 is a diagram illustrating an example of a layer configuration of a charging member of the present invention used in a non-contact charging method.

FIG. 6 is a diagram illustrating an example of a layer configuration of a charging member of the present invention used in a non-contact charging method.

FIG. 7 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus having the charging member of the present invention.

FIG. 8 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus having the charging member of the present invention.

FIG. 9 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus having the charging member of the present invention.

FIG. 10 is a graph showing the relationship between the resistance value of the conductive polyurethane resin of the present invention and the polyurethane resin containing untreated carbon dispersed therein and the amount of carbon added.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive support 2 Elastic layer 3 Conductive layer 4 Resistive layer 5 Primary charging member of the present invention 6 Image exposure means 7 Developing means 8 Corona charger for transfer charging 9 Cleaning means 10 Pre-exposure means 11 Electrophotographic photosensitive member 12 Transferred member 13 Corona charger for primary charging 14 Charging member for transfer charging of the present invention 15 Charging member for static elimination charging of the present invention

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-270767 (JP, A) JP-A-58-100855 (JP, A) JP-A-59-50450 (JP, A) JP-A-59-50 91133 (JP, A) JP-A-5-88507 (JP, A) WO 88/3545 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/02 101 G03G 15 / 08 501 G03G 15/16 103 G03G 121/06 G03G 9/08-9/097 C08L 75/06

Claims (12)

(57) [Claims] 1. An electrophotographic charging member having a resin layer on a conductive support, wherein the resin layer is obtained by polymerizing a monomer having an ethylenically unsaturated group in the presence of carbon and a polyol. A charging member for electrophotography, comprising a polymer mixture and a conductive polyurethane resin obtained by reacting a polyisocyanate. 2. The charging member for electrophotography according to claim 1, wherein the electrophotographic photosensitive member is charged by applying a voltage to the charging member. 3. The charging member for electrophotography according to claim 2, wherein the applied voltage is a DC voltage only. 4. The charging member according to claim 2, wherein the applied voltage is a voltage obtained by superimposing a DC voltage and an AC voltage. 5. The charging member for electrophotography according to claim 1, wherein the charging member is a charging member for primary charging. 6. The charging member for electrophotography according to claim 1, wherein the charging member is a charging member for transfer charging. 7. The charging member for electrophotography according to claim 1, wherein the charging member is a charging member for static elimination charging. 8. The charging member having a volume resistivity of 10 ² to 10 ¹⁰
2. The charging member for electrophotography according to claim 1, wherein said charging member is Ω · cm. 9. A 10-point average surface roughness of the charging member surface of 5
2. The charging member for electrophotography according to claim 1, which has a thickness of not more than μm. 10. The charging member for electrophotography according to claim 1, wherein the charging member is in contact with the surface of the electrophotographic photosensitive member. 11. The charging member for electrophotography according to claim 10, wherein the compression set of the charging member is 40% or less. 12. The charging member for electrophotography according to claim 10, wherein the surface hardness of the charging member is 50 ° or less.