JPH06149071A - Electrode type donor developing device - Google Patents

Abstract

PURPOSE: To obtain an improved resistant coating having a wider forming allowance range and a long cycle operating life by including an overcoating contg. charge implantation particles and a charge transfer material. CONSTITUTION: The resistant coating includes the overcoating contg. the charge implantable particles (particles allowing charge implantation) which can be dispersed into a binder resin and the charge transfer molecules. The binder material is an arbitrary material which can hold the charge transfer molecules in a solid soln. or as a molecule dispersion. The solid soln. is defined as a compsn. in which at least one component dissolves in another component and exists as a homogeneous solid phase. The charge transfer molecules are capable of transporting the charge carriers implanted by the charge implantable particles. As a result, the respective electrodes of the electrode type donor device are protected against wear and the shorting and destruction of the donor developing device are prevented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrode type donor developing device.
(electroded donor development system), and more particularly, to an improved overcoating for an electroded donor device and a method of making the same.

[0002]

2. Description of the Prior Art Electrode donor developing devices rely on statically deposited imaging surfaces to be deposited on the electrically insulating imaging surface as it passes through the development zone (ie, the area where toner particles are transferred from the donor device to the imaging surface). Used in an electrostatographic processor for developing a latent image. For example, the imaging surface can be a photoconductive layer coated on a conductive imaging member that is held at a predetermined reference potential, such as a grounding conductor. The electroded donor developing device has a housing supporting at least one donor device adjacent to the developing zone. The donor device is positioned a predetermined short distance from the imaging surface and is driven to carry toner near the imaging surface as it moves through the development zone. The toner on the electrode type donor device is supplied by a magnetic brush developing device. The developer can be a mixture of triboelectrically charged toner and carrier particles. Examples of suitable toner particles that can be used in magnetic brush developers are described in US Pat. No. 3,977,871.

One of the main purposes of magnetic brush developers is to transport the developer into or through the toner loading area under the influence of a magnetic field, which causes the developer to reach the donor device surface. Formed into a bristle-like stream that is brushed. These bristles or streams are, in any event, within a relatively narrow region (hereinafter referred to as the "loading nip" region) centered on the line where the donor device is closest to the magnetic brush developer. Proceed only.
The magnetic brush developing device carries the magnetically-entrained developer from a pick-up point located upstream of the nip area to a discharge point located downstream of the nip area. Electrode donor developer devices are known in xerographic development systems.
Electrode donor devices are also described in US Pat. Nos. 3,996,892 and 4,568,955. These electrode-type devices include electrically disconnected conductors embedded in an insulating layer. An AC / DC voltage is applied to activate each electrode using a conductive contact brush or roll at one end of the donor. In the device disclosed in U.S. Pat. No. 4,568,755, a voltage is applied to a conductive brush to form a coating of toner on the surface of the activated electrode zone to charge the toner development. Going on the image receiver.

US Pat. No. 3,996,892 discloses 1 to 25 mils (25.4 to 635) doped with carbon black for coating electrodes on a developer roll.
μm) thick conductive rubber insulation layer is disclosed. This coating has a resistance value of 10 ⁷ to 10 ⁹ ohm-cm as reported. The overcoating on the electroded roll provides a resistive layer to protect the electrode from wear. The overcoating also prevents shorting and destruction of the device during the toner loading process, such as when in contact with conductive magnetic brush carrier beads.
Destruction can also occur during toner charging, metering and development when other AC / DC voltages are applied. Overcoatings used in donor devices are based on conductive particles such as carbon black dispersed in a binder. The desired resistance value is obtained by adjusting the filling amount of the conductive material. However, very small changes in the loading of conductive material near the percolation threshold cause dramatic changes in resistance. Also, these coatings are often not sufficiently durable, and resistance heat is often observed when activating the electrodes, causing coating burnouts, short circuits, and device failure.

[0005]

Although resistive coatings for the electrodes of donor devices exist, improved resistive coatings with wider fabrication latitude and longer cycle operating life for electroded donor developers. Is still required.

[0006]

According to the present invention, charge-injecting particles that can be dispersed in a binder resin (that is, particles that can perform charge injection, charge injection enabling part).
The present invention provides an electrode-type donor device that includes an overcoating that includes particles) and charge transport molecules. This dielectric overcoating protects each electrode of the electroded donor device from wear and prevents shorting and destruction of the donor developing device. The present invention relates to an improved overcoating for electroded donor devices. Resistive overcoatings on these devices include charge transporting molecules and charge injecting particles that can be dispersed in a binder resin. These resistive overcoatings do not rely on particle-to-particle contact for charge transport through the overcoating layer, and thus the% charge-injecting particles within the overcoating that will reduce the mechanical strength of the binder. Capacity can be reduced. While not intending to limit the invention to a particular theory, for example, when an electric field is generated in the overcoating layer during the electrode activation process, the charge injectable particles are polarized and charge is injected into the transport medium. It is thought to be done. The injected charge is driven through the overcoating by charging an electric field that is actually neutral. Thus, the space charge within the bulk of the overcoating is mitigated by charge ejection. The developing field created during the toner loading or image development process is not strong enough to cause charge redistribution and destruction during electrode-type donor overcoating.

Toner jar in the above overcoating
The threshold value depends on the toner load.
However, about 200 to about 1,000 V_ACIs in the range. these
The limit value is that the toner should be ejected from the surface of the donor device.
Is the minimum value of the AC amplitude. The lower the electric field amplitude, the more
Since the possibility of electrical breakdown of the bar coating is reduced,
More desirable. Toner jumping limit value
Is about 500-800V _ACIs the range. Above over
The electric resistance value of the coating layer is about 10^Ten-10 ¹⁸Oh
Mu-cm, preferably about 10¹²~ About 10¹⁶Ohm-cm
Is the range. Dielectric strength of the above coating
Causes damage even with a conductive magnetic brush of about 500V.
Negatively put toner on the overcoating layer without slipping
High enough to load. The relative permittivity is about 3 to about 12
It is preferably in the range of about 3 to about 8. That is, the above
The bar coating covers the toner loading zone and the development zone.
AC / DC voltage is applied to the electrode type donor device at
The toner load and band without causing damage.
Enables charging, weighing and development.

Any suitable insulating film forming binder having high dielectric strength and good electrical insulation may be used in the continuous charge transport phase of the overcoating of the present invention. The binder material can be any material that can hold the charge transport molecules in solid solution or as a molecular dispersion. Solid solution is defined as a composition in which at least one component is dissolved in another and is present as a homogeneous solid phase. A molecular dispersion is defined as a composition in which particles of at least one component are dispersed in another component, the dispersion of the particles being molecular scale. Typical film forming binders (not charge transporting materials) suitable in the practice of the present invention include, but are not limited to, polycarbonates, polyesters as disclosed in US Pat. No. 4,515,882. , Polyamide, polyurethane, polystyrene, polyaryl ether, polyaryl sulfone, polybutadiene, polysulfone, polyether sulfone, polyethylene, polypropylene, polymethylpentene, polyphenylene sulfide, polyvinyl acetate, polysiloxane, polyacrylate, polyvinyl acetal, polyimide, amino Resin, phenylene oxide resin, terephthalic acid resin, epoxy resin, phenol resin, polystyrene-acrylonitrile copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copoly Chromatography, acrylate copolymers, alkyd resins, cellulosic film formers, poly (amide - imide), styrene - butadiene copolymer, vinylidene chloride - vinyl chloride copolymers, vinyl acetate - polyvinylidene chloride copolymer, styrene - and alkyl resins. The binder material may comprise about 10 to about 90% by weight of the overcoating layer, preferably about 25 to about 75%.

Any suitable film forming polymer having charge transport capability may be used as the binder in the continuous phase of the overcoating of the present invention. The charge transporting binder may be a hole transporting or electron transporting film forming polymer. Suitable charge transporting film forming polymers include, but are not limited to, the following materials or mixtures thereof: polyvinylcarbazole, and Lewis acid derivatives described in US Pat. No. 4,302,521. Vinyl aromatic polymers such as polyvinyl anthracene and polyacenaphthylene; condensation products of formaldehyde and various aromatic compounds such as condensation products of formaldehyde and 3-bromopyrene; US Pat.
72,717, 2,4,7-trinitro-fluorene and 3,6-dinitro-N-t.
-Butyl naphthalimide. Poly-1-vinylpyrene, poly-9-vinylanthracene, poly-9- (4-pentyl) -carbazole, poly-9- (5-hexyl) -carbazole, polymethylenepyrene, poly-1- (pyrenyl) -butadiene Poly-3-aminocarbazole,
Polymers such as alkyl, nitro, amino, halogen and hydroxy substituted polymers such as 1,3-dibromo-poly-N-vinylcarbazole and 3,6-dibromo-poly-N-vinylcarbazole; and US Pat. Other transportable materials such as a number of other organic polymeric transportable materials such as those described in US Pat.

Any suitable charge transport molecule that can act as a film-forming binder or that is soluble or molecularly dispersible in the film-forming binder can be used in the overcoating of this invention. The charge transport molecule must be able to transport the charge carriers injected by the charge injecting particles at a given electric field. The charge transport molecule can be a hole transport molecule or an electron transport molecule. When the charge transport molecule can also act as a film-forming binder as described above, if necessary, it serves as an insulating binder for the charge injecting particles, and as a solid solution or a molecular dispersion, different charge transport molecules. It can be used to function both as a continuous charge transporting phase that does not require the use of molecules. Other suitable non-film forming charge transport materials other than the polymers having charge transport capability described above include, but are not limited to:

Diamine transport molecules include, but are not limited to, compounds having the following general formula:

[Chemical 1] (In the formula, X is selected from the group consisting of an alkyl group having about 4 to about 4 carbon atoms and chlorine.) This compound is N, N ^, -diphenyl-N, N ^, -bis (3 "- Methylphenyl)-[1,1 ^, -biphenyl] -4,4 ^,
-Diamine, N, N ^, -diphenyl-N, N ^, -bis (4-methylphenyl)-[1,1 ^, -biphenyl]-
4,4 ^, -diamine, N, N ^, -diphenyl-N, N ^,
-Bis (2-methylphenyl)-[1,1 ^, -biphenyl] -4,4 ^, -diamine, N, N ^, -diphenyl-
N, N ^, -bis (3-ethylphenyl)-[1,1 ^, -
Biphenyl] -4,4 ^, -diamine-like N, N ^, -
Diphenyl-N, N ^, -bis (alkylphenyl)-
[1,1 ^, -biphenyl] -4,4 ^, -diamine (wherein alkyl is, for example, methyl, ethyl, propyl,
n-butyl and the like) or the compound is N, N ^, -diphenyl-N, N ^, -bis (chlorophenyl)-, as disclosed in U.S. Pat. No. 4,515,882. It may be [1,1 ^, -biphenyl] -4,4 ^, -diamine and the like.

Pyrazoline transport molecules include, but are not limited to, 1- [repidyl- (2)]-3- (p-diethylaminophenyl) as disclosed in US Pat. No. 4,515,882. -5- (p-diethylaminophenyl) pyrazoline, 1- [quinolyl- (2)]-3-
(P-Diethylaminophenyl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl-
(2)]-3- (p-Diethylaminostyryl) -5-
(P-Diethylaminophenyl) pyrazoline, 1- [6
-Methoxypyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl)
Pyrazoline, 1-phenyl-3- (p-dimethylaminostyryl) -5- (p-dimethylaminostyryl) pyrazoline, 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazolin, etc. There is. Exemplary fluorene charge transport molecules include, but are not limited to, US Pat. No. 4,515,882.
9- (4′-dimethylaminobenzylidene) fluorene, 9- (4′-methoxybenzylidene) fluorene, 9- (2 ′, 4′-dimethoxybenzylidene) fluorene, 2-nitro-9. -Benzylidene-fluorene, 2-nitro-9- (4'-diethylaminobenzylidene) fluorene and the like.

Oxadiazole charge transport molecules include, but are not limited to, 2,5-bis (4-diethylaminophenyl-1,3, as disclosed in US Pat. No. 4,515,882. 4-oxadiazoles, pyrazolines, imidazoles, triazoles, etc. Hydrazones as described in US Patent No. 4,515,882. Preferred hydrazones are compounds having the general formula:

[Chemical 2] In the above formula, R ₁ is

[Chemical 3] R ₂ is —OCH ₂ CH ₃ , —CH ₃ or —
H is; R ₃ is

[Chemical 4] It is -CH ₃ or _{-CH 2 CH 2 CH 2 CH 3} ; R
₄ is

[Chemical 5] Or -CH _3.

Typical examples of hydrazone transport molecules included in the above formula include, for example, US Pat. No. 4,150,9.
No. 87, p-diethylaminobenzaldehyde- (diphenylhydrazone), o-ethoxy-p.
-Diethylaminobenzaldehyde- (diphenylhydrazone), o-methyl-p-diethylaminobenzaldehyde- (diphenylhydrazone), o-methyl-p-
Dimethylaminobenzaldehyde- (diphenylhydrazone), p-dipropylaminobenzaldehyde- (diphenylhydrazone), p-diethylaminobenzaldehyde- (benzylphenylhydrazone), p-dibutylaminobenzaldehyde- (diphenylhydrazone), p-dimethylaminobenzaldehyde- ( Diphenylhydrazone) and the like. Other hydrazone transport molecules include 1-naphthalenecarbaldehyde-1-methyl-1.
Compounds such as -phenylhydrazone, 1-naphthalenecarbaldehyde-1,1-phenylhydrazone, 4-methoxynaphthalene-1-carbaldehyde 1-methyl-1-phenylhydrazone; and, for example, U.S. Pat. No. 4,385,106. There are other hydrazone transport molecules disclosed in Nos. 4,338,388; 4,387,147, 4,399,208 and 4,339,207.

Another preferred charge transport molecule is carbazole phenylhydrazone having the general formula:

[Chemical 6] (In the formula, R ₁ is a methyl, ethyl, 2-hydroxyethyl or 2-chloroethyl group; R ₂ is methyl,
It is an ethyl, benzyl or phenyl group. ) Typical examples of transport molecules included in the above formula include 9-methylcarbazole-3-carbaldehyde-1,1-diphenylhydrazone, 9-ethylcarbazole-3-carbaldehyde-1-methyl-1. -Phenylhydrazone, 9-
Ethylcarbazole-3-carbaldehyde-1-ethyl-1-phenylhydrazone, 9-ethylcarbazole-3-carbaldehyde-1-ethyl-1-benzyl-
1-phenylhydrazone, 9-ethylcarbazole-3
-Carbaldehyde-1,1-diphenylhydrazone,
And there are other suitable carbazole phenyl transport molecules described in, for example, US Pat. No. 4,256,821. Similar hydrazone transport molecules are described, for example, in US Pat. No. 34,297,426.

US Pat. Nos. 4,150,987; 4,
The invention can also be practiced with other suitable charge transporting molecules described in 256,821 and 3,820,989. Other typical transport materials include many organic non-polymeric transport materials described in US Pat. No. 3,870,516, and nonionics described in US Pat. No. 4,346,157. There are sex compounds. Other suitable transport materials include, but are not limited to, poly-1-vinylpyrene, poly-9-vinylanthracene, poly-9.
-(4-Pentenyl) -carbazole, poly-9- (5
-Hexyl) -carbazole, polymethylenepyrene, poly-1- (pyrenyl) -butadiene; poly-3-aminocarbazole, 1,3-dibromo-poly-N-vinylcarbazole and 3,6-dibromo-poly-N- There are alkyl, nitro, amino, halogen and hydroxy substituted polymers such as vinylcarbazole; and many other organic polymeric or non-polymeric transportable materials such as those described in US Pat. No. 3,870,516. . The charge transport molecules are mixed with the insulating film forming binder using an insulating film forming binder to charge transport molecule ratio of about 10 to about 90 parts by weight, preferably about 25 to about 75 parts by weight. The charge transport molecules make up about 10 to about 90% by weight of the overcoating layer, preferably about 25 to about 75%.

Any suitable organic or inorganic charge injectable particles may be used in the overcoating of this invention. The charge injecting particles can be hole injecting particles or electron injecting particles. Any particle can function as a charge injecting particle as long as the concentration of particles and the overall electric field cause the charge injecting particles to rapidly polarize and charge carriers to be injected during the continuous phase of the overcoating layer. In general,
Charge injecting particles having an electrical resistance value of about 10 ¹² ohm-cm or less are suitable. Typical inorganic charge injectable particles include, but are not limited to, US Pat. No. 5,063,
128; No. 5,063,125 and No. 4,51
Molybdenum disulfide, silicone, carbon black, graphite, tin oxide, antimony oxide, chromium dioxide, zinc oxide, titanium dioxide, magnesium oxide, manganese dioxide, aluminum oxide, other metal oxides as disclosed in 5,882. , Colloidal silica, silanized colloidal silica, tin, aluminum, nickel, steel, silver, gold, other metals, their oxides, sulfides, halides, and other salt forms.

Typical examples of organic charge injecting particles include, but are not limited to, fluorinated carbon particles; phthalocyanine pigment particles; quinacridone pigment particles; tetracyanoquinodimethane (TCNQ) and polymeric quaternary. Ammonium salt,
Conductive composites with poly (2-vinylpyridene), poly (4-vinylpyridene), poly (N-vinylimidazole), poly (4-dimethylaminostyrene) and ionene polymers; black brominated poly (cyclopentadiene); Polymer reaction product of poly (alkyl vinyl ketone) and phosphoryl chloride; metal polyphthalocyanine; tetranitrile prepared at about 200 ° C. from tetracyanoethylene solution phase deposited on metal surface; Ziegler-Natta catalyst [Ti ( _{OC 4 H 9 -n) 4 -Al} (C 2 H 5) polyacetylene trans isomer prepared by exposing acetylene to the film of a concentrated solution of _3]; poly (p-
Phenylene oxide); polypyrrole prepared by electrolysis of pyrrole; poly (2,5-thienylene); poly (phenylacetylene), polyyne (200-600 ° C.)
Thermal decomposition), poly (acyl acetylene) (400-87
Conductive polymer prepared by thermal decomposition of 0 ° C), high molecular Schiff base (500 ° C) or polyaminoquinone (500 ° C); Cu ²⁺ Ni (S ₂ C ₂ (C
N) ₂ ) ₂ ^2- ; Copper tetracyanoquinodimethane; Potassium tetracyanoquinodimethane; Sodium tetracyanoquinodimethane; Lithium tetracyanoquinodimethane; Complex of anthracene and tetracyanoquinodimethane; Pyrene and Complex with tetracyanoquinodimethane; polystyrene sulfonic acid with a high degree of sulfonation [Versa-TL available from National Starch and Chemical Co.
Other organic pigment particles; polypyrroles as disclosed in US Pat. Nos. 5,063,128; 5,063,125 and 4,515,882; There are polyaniline, polyaromatic conductive polymers, and polythiotenes.

Fullerene carbon can also be used as charge injecting particles. Other charge injecting species are copper (I) compounds such as cuprous iodide described in US Pat. No. 5,120,628. Examples of other charge injection particles are listed in Table 1 below:

Table 1 Charge injecting particle compound Charge transporting salt Cu TCNQ K TCNQ Li TCNQ Fe (phen) ₃ ⁺⁺ (TCNQ) ₂ Fe (phen) ₃ ⁺⁺ (TCNQ) ₂ (phen) ₃ CH ₃ P ( TCNQ) Complex Anthracene TCNQ Pyrene TCNQ Macrocyclic compound (n = 2 to 25) [Si (phthalocyaninato) O] _n [Sn (phthalocyaninato) O] _n [Ge (phthalocyaninato) P ] _n [t-Bu ₄ phthalocyaninate GeO] _n [t-Bu ₄ phthalocyaninate SnO] _n [(bipy) phthalocyaninate iron] _n Dithiolene compound and complex Cu ²⁺ Ni (S ₂ C ₂ (CN) ₂ ) ₂ ^2- H ²⁺ Cu (S ₂ C ₂ (CN) ₂ ) ₂ Ni ²⁺ Cu (S ₂ C ₂ (CN) ₂ ) ₂ ^2- Co ²⁺ Co ₂ (S ₂ C ₂ (CN) ₂ ) ₄ ^2- Co ²⁺ Cu (S ₂ C ₂ (CN) ₂ ) ₂ ^2- Ni (S ₂ C ₂ Ph) ₂ Ni (S ₂ C ₂ Me ₂ ) ₂ Fe ₂ (S ₂ C ₂ Ph ₂ ) ₄ Fe ²⁺ Fe ₂ (S ₂ C ₂ (CN) ₂ ) ₄ ^2- (NMe ₄ ⁺ ) ₂ Cu (S ₂ C ₂ (CN) ₂ ) ₂ ^2- Mo (S ₂ C ₂ H ₂ ) ₃ H ⁺ Fe ₂ (S ₂ C ₂ (CN) ₂ ) ₄ W (S ₂ C ₂ Ph ₂ ) ₃ NMe ₄ ⁺ Fe ₂ (S ₂ C ₂ (CN) ₂ ) ₄ ^2- Mo (CO ) ₂ (S ₂ C ₂ Me ₂ ) ₂

Particle size of charge injection particles (volume average particle size)
Should be less than about 45 μm. About 100
We have found that a particle size of about 5000 Angstroms is suitable. Generally, the overcoating layer of the present invention should contain at least about 0.1% by weight of charge injectable particles, based on the total weight of the overcoating layer. At lower concentrations, a clear residual charge tends to occur. The upper limit of the amount of charge-injecting particles used depends on the relative amount of desired charge flow through the overcoating layer, the charge injection efficiency of the charge-injecting particles and the electric field applied to the overcoating. Satisfactory results are obtained in polycarbonate resin containing dissolved N, N ^, -diphenyl-N, N ^, -bis (3-methylphenyl) 1,1 ^, -biphenyl-4,4 ^, -diamine (charge transport molecule). In the case of relatively poor charge-injecting particles of silica particles dispersed in, 50 wt.
Obtained with charge injectable particle concentrations as high as weight percent.
The concentration of charge-injecting particles should be well below about 50% by weight, based on the total weight of the overcoating layer, when using efficient and highly conductive charge-injecting particles.
For example, the overcoating layer dissolves the above silica particles and is a polycarbonate resin containing N, N ^, -diphenyl-N, N ^, -bis (3-methylphenyl) 1,1 ^, -biphenyl-4,4 ^, -diamine. Dispersed in 50
Weight% concentration (based on total weight of overcoating layer)
When replaced with the carbon black charge injection particles of
Involuntarily becomes conductive in the applied electric field.

The components of the overcoating of the present invention may be mixed together by any suitable means. Typical mixing means include, for example, a stir bar, an ultrasonic vibrator, a magnetic stirrer, a paint shaker, a sand mill, a roll pebble mill, a sonic mixer, and a melt mixing device. However, it is important to note that if the insulating film-forming binder is a different material than the charge-transporting molecule, the charge-transporting molecule will either dissolve in the insulating film-forming binder or be dispersed in the insulating film-forming binder. It should be possible. Solvents or solvent mixtures for the film-forming binder and charge transport molecules can be used if desired. Preferably the solvent or solvent mixture should dissolve both the insulative film forming binder and the charge transport molecule. Examples of suitable solvents include, but are not limited to, methylene chloride, 1,1,2-trichloroethane, methyl ethyl ketone, toluene, xylene, tetrahydrofuran and the like. The overcoating of the present invention may be coated on any suitable electroded donor device. These electrode-type donor devices can be in the form of rolls, belts, drums, rods, scrolls or sheets. Examples of suitable electrode-type donor devices that may be used in practicing the present invention are US Pat. Nos. 3,996,892 and 4,568,95.
No. 5 is described.

The overcoating of the present invention may be applied to the electroded donor device by any suitable means. Typical methods of applying overcoating to donor devices include, for example, spray coating, dip coating, wire wound rod coating, powder coating, electrostatic spraying, sonic spraying, blade coating, web coating, fluidized extrusion and the like. There are various methods. When the overcoating of the present invention is applied by spraying, the spraying can be done with or without the aid of gas. Spraying may be aided by mechanical and / or electrical assistance as in electrostatic spraying. The overcoating of the present invention should be uniform, smooth and free of defects such as entrapped gas, bubbles, dirt, debris and the like. The overcoating of the present invention may be dried using any suitable conventional drying or curing method used in the art. Drying or curing conditions should be chosen to avoid damaging the underlying donor device. Typical drying temperatures are in the range of about 20 to about 150 ° C, preferably about 30 to about 130 ° C. The thickness of the overcoating layer of the present invention after drying or curing may preferably be from about 1 to about 50 μm. Generally about 1μ
Overcoating thicknesses less than m do not provide sufficient protection to the underlying electrode-type donor device. High protection is obtained with an overcoating thickness of at least about 3 μm. An overcoating thickness of about 3 to about 15 μm is preferred for optimal protection of the electroded donor device.

[0024]

【Example】

EXAMPLE 1 An overcoating layer was formed on 0.6 g of Merlon® M39 polycarbonate (available from Miles, Inc. of Pittsburgh, PA), 0.39 g of US Pat. No. 4,265,990. N, N ^, -diphenyl-N, N ^, -bis (3-methylphenyl)-[1,1 prepared as described.
^, -Biphenyl] -4,4 ^, -diamine, and 0.0
1 g of Black Pearls (registered trademark)
It was prepared by mixing 2000 carbon black (available from Cabot, Inc., Billerica, Mass.). The ingredients of these overcoating compositions were applied to the paint shaker Red Devil.
l) 3.2 mm in Model No. 5100X (available from Red Devil Corp. of Union, NJ, USA)
A dispersion was obtained by mixing with diameter stainless steel balls in methylene chloride for about 90 minutes. This overcoating composition was coated with a polyimide film sheet by a Gardner stretch bar coater equipped with a coating bar having a 0.002 inch (50.8 μm) gap for applying a wet film thickness that gives a coating thickness of about 5 μm when dried. The above axially oriented electrode was applied to a thickness of 1 mil (25.4 μm). The resulting overcoating was dried overnight at room temperature. The overcoated electrode film was laminated on an aluminum roll to obtain a donor roll.

The applicator donor roll was incorporated into a magnetic brush developer for an electrostatographic processor for developing an electrostatic latent image. The imaging surface was a conventional drum type xerographic photoreceptor well known in the art. The overcoating of the present invention prevents electrical shorts between the electrodes on the donor roll and the conductive magnetic brush used to feed the toner onto the donor roll. 10 mil (254 μm) gap and about 1.5K
At an AC bias of about 600 volts peak at Hz,
A uniform solid area was obtained with an insulating toner and a synchronized speed between the donor roll and the image receiver of 10 cm / sec. The highest developed toner M / A (mass density of toner developed from the donor onto the latent image) was about 0.45 mg / cm ² at a donor roll loading of about 0.50 mg / cm ² . This value indicates a developing efficiency of about 0.9, that is, about 90%.

[0026]

Example 2 The overcoating layer was applied as in Example 1 above.
Was prepared as described above, but 0.6 g of Lexan (L
ekan® 4701 Polyphthalate Carbonate Resin (General of Pittsfield, Mass.)
(Available from Electric Company) was used in place of Merlon M39 polycarbonate. This overcoating was applied to the axially oriented electrode material as described in Example 1 to give a dry overcoating thickness of about 6 μm. This applicator donor roll was incorporated into a magnetic brush development device for developing electrostatic latent images as in Example 1. This overcoating has a 10 mil (254 μm) gap between the photoreceptor and the donor roll and about 1.5
An AC bias of about 600 volts peak at KHz prevented electrical shorts between the electrodes on the donor roll and the conductive magnetic brush used to feed the toner onto the donor roll. A uniform solid area was obtained with red toner at a synchronized speed between the donor roll and the image receiver of 10.2 cm / sec. The maximum developed mass density of the toner developed on the latent image from the donor is about 0.42 mg / cm ² , which corresponds to a development efficiency of about 70%. The difference in development efficiency between the overcoating of Example 1 and Example 2 is due to the increased toner adhesion to the polyphthalate carbonate binder of the overcoating of Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Donald S. Sipra New York, USA 14526 Penfield Jackson Road Extension 138 (72) Inventor Merlin Escharf, New York, USA 14526 Penfield Valley Green Drive 273 (72) Inventor Paul Jay Blatch USA New York 14617 Rochester Oak Bend Lane 15 (72) Inventor Michael A. Morgan USA New York 14450 Fairport Covernet Circle 6 (72) Inventor Michael Dee Thompson USA New York 14620 Rochester Rockingham Street 112

Claims (1)

[Claims] 1. An electroded donor device comprising an overcoating comprising charge injecting particles and a charge transport material.