JPH07191473A - Production of electrophotographic imaging member - Google Patents

Abstract

PURPOSE: To manufacture the imaging member which contains a charge generation layer having low dark decay and high sensitivity by using a mixture that comprises X-form nonmetallo-phthalocyanine particles dispersed in a coating film forming polymer solution consisting of a specific polymer and a specific ketone solvent. CONSTITUTION: In this manufacture, a mixture which consists of a pigment dispersion comprising X-form nonmetallo-phthalocyanine particles dispersed in a coating film forming polymer solution consisting of a polymer represented by the formula and a solvent that comprises a ketone having a boiling point within the range of 75 to about 160 deg.C, is used. In the formula: (x) is a numerical value equivalent to a polyvinyl butyral component ratio in the range of about 50 to 75mol%; (y) is a numerical value equivalent to a polyvinyl alcohol component ratio in the range of about 12 to 50mol%; and (z) is a numerical value equivalent to a polyvinyl acetate component ratio in the range of about 0 to 15mol%. The X-form nonmetallo-phthalocyanine particles dispersed in the coating film forming polymer solution are applied to a substrate to form a coating film on the substrate and then, the coating film is dried to form a charge generation layer and further, a charge transfer layer is formed to manufacture the objective imaging member.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates generally to electrophotographic imaging members, and more particularly to a method of making an electrophotographic imaging member having an improved charge generating layer.

[0002]

BACKGROUND OF THE INVENTION Conventional techniques for coating cylindrical or drum photoreceptor substrates include the step of immersing the substrate in a coating bath. The liquid tank used for making the photoconductive layer is
It is prepared by dispersing photoconductive pigment particles in a solvent solution of a film-forming binder. Unfortunately, some organic photoconductive pigment particles are not applicable for forming high quality photoconductive layers by dip coating. For example, organic conductive pigment particles, such as vanadyl phthalocyanine pigments or metal-free phthalocyanine pigments, tend to form "marbled" photoconductive coatings. As used herein, a marbled coating is defined as a coating consisting of a series of horizontal lines, fine lines and patterns on a coating without pigmentation.
A photoconductive coating with a marbled pattern is undesirable for electrophotography because such imperfections manifest as unwanted patterns in the final print.

In addition, some dispersions are not preferred as they are very thixotropic and shear thinning, and may show up as photoreceptor defects or marble patterns on the coated surface. This type of dispersion has
Marble pattern defects are more likely to occur because they rely on the shear forces created in the dip coating process to deposit the charge generating coating on the photoreceptor substrate.

Also, the photoconductive pigment milling process using a medium such as steel is inefficient, labor intensive, and the presence of milling media for particle milling creates the potential for pigment contamination. To increase.

Thus, in general, the process of making charge generating layer dispersions for coating applications is complicated, time consuming, and involves rolling milling with media to reduce particle size, and large particles. , Steps such as centrifugation steps to separate particles of about 1 micron and larger. In this way, the process of preparing a known charge generation layer dispersion is labor intensive and costly.

US Pat. No. 5,168,022 discloses a process for making a photoconductive pigment having a small particle size, wherein a polymorphic pigment is produced by a conversion process,
That is, in the process, a specific amount of the required polymorphic pigment, such as X-form metal-free phthalocyanine, and a large amount of another polymorphic pigment, are treated in a liquid jet interaction process. A preferred device for performing the liquid jet interaction process is a Microfluidizer (Microfluidizer).
This is an emulsifying machine. The particle size obtained from this step can be as small as 0.05-0.1 micron. The preferred solvents for this slurry are methyl ethyl ketone and cyclohexanone. The pigment can be further processed to obtain a pigment well dispersed in the binder coating the photoreceptor. At this stage, the liquid jet interaction chamber redisperses the pigment by using a solvent that can add a binder during processing as a slurry liquid, or the binder itself as a slurry liquid to disperse the coating agent. It can be used to directly produce the contained pigments. Various polymeric binders can be selected for the X-foam metal-free phthalocyanine photogenerating layer, such as polycarbonate, polyester, polyvinyl butyral, polyvinyl acetate, polyvinyl carbazole, polyacrylic acid ester, polystyrene, and copolymers thereof. .

A film-forming binder of polyvinyl butyral copolymer (BM-S available from Sekisui Chemical Co., Ltd.) was dissolved in cyclohexanone, X-form metal-free phthalocyanine and cyclohexanone were added, and the resulting mixture was then mixed. It is also known to make dispersions by grinding in a horizontal grinder using glass beads. After centrifuging the resulting dispersion and collecting the supernatant, a dispersion containing the pigment having an average particle size of about 0.3 to 0.4 micron can be obtained.
This solution can be filtered or further diluted to form a charge generating layer using dip coating equipment. After coating with a charge transport layer, these photoreceptors have been found to have relatively high dark color attenuation and low sensitivity.

[0008]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved method of overcoming the above deficiencies.

[0009]

SUMMARY OF THE INVENTION The present invention uses 75 ° C. and about 1 ° C.
From a pigment consisting essentially of a solvent consisting essentially of a ketone having a boiling point between 60 ° C. and X-form metal-free phthalocyanine particles in a solution of a film-forming polymer consisting essentially of a polymer represented by the general formula: Providing a mixture composed of:

[Chemical 2] Where x is a number such that the polyvinyl butyral component is a mole percent between about 50 and about 75 and y is
A number such that the polyvinyl alcohol component is between about 12 and about 50 mole percent, and z is such that the polyvinyl acetate component is between about 0 and 15 mole percent, and A shearing force is applied to the X
Substantially grinding all of the foam metal-free phthalocyanine particles to an average size of less than about 2 microns, forming the mixture into at least one stream, high pressure and high velocity of the stream from at least one nozzle. And with sufficient force to grind the particle size of the X-foam metal-free phthalocyanine particles to an average size of less than about 0.6 microns dispersed in the solution of the solvent and the film-forming polymer. Bombarding the jet stream of the target with a target, providing a substrate to be coated, and applying the dispersed X-form metal-free phthalocyanine particles to the substrate to form a coating. Drying the coating to remove substantially all of the cyclohexanone solvent to form a dried charge generating layer, and forming a charge transport layer. It is achieved by Rukoto.

Electrostatographic imaging members are well known in the art.
Generally, a substrate having a conductive surface is provided. At least one photoconductive layer is then applied to this conductive surface. A charge blocking layer may be applied to the conductive surface prior to applying the photoconductive layer. If desired, an adhesive layer can be used between the charge blocking layer and the photoconductive layer. In the case of multilayer photoreceptors, a charge generating binder layer is usually applied on the blocking layer and a charge transport layer is formed on the charge generating layer. However, if desired, the charge generation layer may be applied to the charge transport layer.

The substrate can be opaque or substantially transparent and can be composed of many suitable materials with the required mechanical properties. Thus, the substrate can be composed of layers of conductive or non-conductive materials such as inorganic or organic formulations. As non-conductive materials, various resins known for this purpose can be used, including flexible polyesters such as rigid or thin webs, polycarbonates, polyamides, and polyurethanes.

Since the thickness of the substrate layer depends on many factors, including beam strength and economic considerations, this layer for flexible belts should be used as long as it does not adversely affect the final electrostatographic device. , Can be of considerable thickness, for example about 125 microns thick, or a minimum thickness of less than 50 microns. In one flexible belt embodiment, the thickness of this layer is in the range of about 65 microns to about 150 microns, and has optimal flexibility when circulating around small diameter rollers, such as 19 millimeter diameter rollers. Preferably in the range of about 75 microns to about 100 microns so that Substrates in the form of drums or cylinders can be constructed of metal or plastic of suitable thickness, or a combination of metal and plastic, depending on the degree of rigidity required.

The conductive layer can vary in thickness over a substantially wide range depending on the optical transparency and tortuosity required for the electrostatographic member. Therefore, in the case of a bendable photo-responsive imaging device, the thickness of the conductive layer is between about 20 angstrom units and about 750 angstrom units.
It is more preferably in the range of about 100 angstrom units to about 200 angstrom units when the conductivity, flexibility and light transmittance are optimally combined. The bendable conductive layer may be a conductive metal layer formed, for example, on a substrate by a suitable coating technique such as a vacuum deposition technique. If the substrate is metallic, such as a metal drum, then its outer surface is usually electrically conductive in nature and no separate electrically conductive layer need be applied.

After forming the conductive surface, the hole blocking layer can be applied thereto. Electron blocking layers for photoreceptors, which are generally positively charged, move holes from the imaging surface of the photoreceptor towards the conductive layer. Any suitable blocking layer that can form an electronic barrier to holes between the adjacent photoconductive layer and the underlying conductive layer can be utilized. Blocking layers are well known and are described, for example, in US Pat. Nos. 4,291,110, 4,3.
38,397, 4,286,033 and 4,
No. 291,110. U.S. Pat. No. 4,3
38,397, 4,286,033 and 4,
The disclosure of No. 291,110 is incorporated herein in its entirety. The blocking layer can consist of an oxidized surface that inherently forms on the outer surface of most metal substrate surfaces when exposed to air. The blocking layer can be applied as a coating by any suitable conventional technique such as spraying, dip coating, drawbar coating, gravure coating, screen printing, air knife coating, reverse roll coating, vacuum deposition and chemical treatment. For convenience in obtaining a thin layer, the blocking layer is preferably applied in the form of a dilute solution, with the solvent removed by conventional techniques such as vacuum and heating after deposition of the coating. Drying of the deposited coating can be carried out by any suitable conventional technique such as oven drying and air drying. The blocking layer should be continuous and should be less than about 0.2 microns in thickness, as a large thickness can result in an undesirably high residual voltage.

An optional adhesive layer can be applied to the hole blocking layer. Any suitable adhesive layer known in the art may be utilized. Satisfactory results are obtained with an adhesive layer having a thickness of between about 0.05 micron (500 angstroms) and about 0.3 micron (3,000 angstroms). Conventional techniques for applying the adhesive layer coating mixture to the charge blocking layer include spraying, dip coating, roll coating, wire wound rod coating, gravure coating and bird applicator coating. Drying of the deposited coating can be carried out by any suitable conventional technique such as oven drying, infrared radiation drying and air drying.

The photogenerating layer of the present invention is dispersed in a solution of polyvinyl butyral copolymer of the film-forming polymer of the present invention which is soluble in a solvent consisting of cyclohexanone, about 0.
It can be prepared by coating a coating dispersion of a photoconductive pigment of X-form metal-free phthalocyanine having an average particle size of less than 6 microns. This dispersion can be applied to an adhesive blocking layer, a suitable conductive layer or a charge transport layer. When used in combination with a charge transport layer, the photoconductive layer may be provided between the charge transport layer and the substrate, or the charge transport layer may be provided between the photoconductive layer and the substrate.

X-form metal-free phthalocyanines have been described in the technical literature as well as in US Pat. No. 3,357,989.
It is a well-known photoconductive pigment widely described in patent documents such as 3,594,163 and 3,168,022. The pigment is substantially insoluble in the cyclohexanone used to dissolve the charge generating layer coating forming the polyvinyl butyral copolymer binder.

Satisfactory when the dried photoconductive coating comprises between about 20 weight percent and about 90 weight percent X-foam metal-free phthalocyanine, based on the total weight of the dried photoconductive coating. The result is obtained. When the pigment concentration is less than about 20 weight percent,
As a result of the particle-to-particle contact not being achieved, the sensitivity of the resulting photoreceptor is reduced. When the pigment concentration exceeds about 90 weight percent, the toner image formed on the photoreceptor produced by dip coating has excessively high dark color attenuation. The photoconductive coating formulation of the present invention comprises hydroxygallium phthalocyanine and titanyl phthalocyanine (TiOPc).
It should be substantially free of other types of phthalocyanine particles such as. This is because these other types of phthalocyanine pigment particles require milling to achieve particle reduction and dispersibility, and cannot be well dispersed by the liquid jet interaction process. Preferably, the proportion of X-form metal-free phthalocyanine utilized is between about 20 weight percent and about 90 weight percent. Since the properties of the photoconductor are affected by the relative amount of pigment per square centimeter coated, low pigment loading can be utilized if the dried photoconductive coating layer is thick. Conversely, when thinning the dried photoconductive layer,
High pigment loading is desirable.

In general, when the photoconductive coating is applied by dip coating, satisfactory results are obtained with an average particle size of the photoconductive particles of less than about 0.6 microns. Preferably, the photoconductive particles have an average particle size of less than about 0.4 microns.
However, when other types of coating techniques are utilized, such as roll coating techniques for webs, the photoconductive particles also have an average particle size of less than about 0.6 microns. Preferably, the particle size of the photoconductive particles is also less than the thickness of the dried photoconductive coating layer in which it is dispersed.

For multilayer photoreceptors consisting of a charge generating layer and a charge transport layer, a coating thickness of the dried photoconductive layer of between about 0.1 micron and about 10 microns can give satisfactory results. it can. Preferably, the thickness of the photoconductive layer is
It is between about 0.2 and about 4 microns. However, these thicknesses also depend on the pigment loading. Thus, high pigment loading allows the use of thin photoconductive layer coating thicknesses. Thicknesses outside these ranges can be selected as long as the object of the invention is achieved.

The film-forming polymer utilized as the binder in the photoconductive coating of the present invention is the reaction product of polyvinyl alcohol and butyraldehyde in the presence of a sulfuric acid catalyst. The hydroxyl groups of polyvinyl alcohol react to give a random butyral structure, which can be controlled by varying the reaction temperature and time. The acid catalyst is neutralized with potassium hydroxide. Polyvinyl alcohol is synthesized by hydrolyzing polyvinyl acetate.
The resulting hydrolyzed polyvinyl alcohol may contain some polyvinyl acetate component. Partially or completely hydrolyzed polyvinyl alcohol is a butyl alcohol under conditions where some of the hydroxyl groups of polyvinyl alcohol are reactive, but under conditions where some of the other hydroxyl groups of polyvinyl alcohol remain unreacted. Reacts with aldehydes. For use in the photoconductive layer of the present invention, the reaction product comprises between about 50 mole percent and about 75 mole percent polyvinyl butyral component, about 12 mole percent.
It is necessary to have between about 50 and about 50 mole percent polyvinyl alcohol component and up to about 15 mole percent polyvinyl acetate component. These film-forming polymers are commercially available, eg, about 88 weight percent polyvinyl butyral component, 12 percent polyvinyl alcohol component, less than about 1.5 weight percent polyvinyl acetate component, and about 50,000 and about 50,000. Butvar B-79 resin (available from Monsanto Chemical Company) having a weight average molecular weight between 80,000 and about 80 weight percent polyvinyl butyral component, 19 weight percent polyvinyl alcohol component, about 2.5. Butvar having less than weight percent polyvinyl acetate component and a weight average molecular weight between about 90,000 and about 120,000.
B-76 resin (available from Monsanto Chemical Company),
And a BMS resin (available from Sekisui Chemical) having a polyvinyl butyral component of about 72 percent, a vinyl acetate group component of about 5 weight percent, a polyvinyl acetate component of 0 percent, and a weight average molecular weight of about 93,000. is there. Preferably, the weight average molecular weight of the polyvinyl butyral utilized in the process of the present invention is about 5
It is between 50,000 and about 250,000.

The solvent for the film-forming polymer consists essentially of cyclohexanone, or 75 ° C and about 160 ° C.
It should consist of other suitable ketones such as methyl ethyl ketone or methyl isoamyl ketone or mixtures thereof having a boiling point between ° C. Solvents other than cyclohexanone that dissolve the film-forming binder tend to form dispersions that exhibit instability or other undesirable properties.

A multi-step high energy dispersion technique is necessary to sufficiently disperse the X-form metal-free phthalocyanine pigment in a solution of the polyvinyl butyral copolymer in cyclohexanone solvent and to prevent the marble pattern. This multi-stage high energy dispersion process is fast and efficient, obviating the need for media and media cleaning, and subsequent filtration to remove large particles. The high energy dispersion process is performed in at least two stages. The first step is to apply a sufficiently high shear force by suitable means, such as a high speed rotor / stator stirrer, to eliminate large pigment aggregates having an average size of about 2 microns or more. Including. That is, all pigment particles after application of sufficiently high shear force will have an average particle size of less than about 2 microns. Generally, the rotor of a rotor / stator high-speed agitator consists of a main shaft that is rotatable within a fixed housing called the stator. This fixed part consists of a screen with square holes that provide high speed shear as the dispersion is propelled by the rotor at high speed through the screen. High speed rotor / stator stirrers are commercially available, for example, from Silverson Ma
Chinese Ltd. ) (Silverso, Buckinghamshire, UK)
n) There is a model # L4R. The expression "fast shear" as used herein is defined as the application of dispersing force by the rotor-stator combination in a high speed agitator.

The second stage of the high energy dispersion process involves a liquid jet interaction process. An example of a liquid jet interaction process is described in US Pat. Nos. 4,533,254 and 4,
168,022. A preferred apparatus for performing the liquid jet interaction process is Microfluidics Corpo, Newtown, Mass.
is a Microfluidizer homogenizer available from Ration. The device consists of a liquid jet interaction chamber block consisting of a submerged nozzle with elongated orifices arranged to jet a thin sheet of liquid system under pressure. The nozzles are arranged to carry out a turbulent jet interaction of the sheet along a common liquid jet interaction, and the sheet is jetted by the nozzle into a liquid-filled low-pressure zone, Turbulent jet interactions also occur with the mixture therein and along a common boundary essentially formed by the sheets jetted into the low pressure zone. The device further comprises an inlet channel for delivering the liquid system to the nozzle under pressure and a delivery channel for removing the liquid.

The liquid jet interaction device has a high pressure (up to about 1
A pump of 265 kg / cm ² (18,000 psi)) can be used which forces a mixture of materials in a non-aqueous medium into the chamber where it is split into at least two streams. , Passing through at least two slits at high speed and colliding, so that the particles of the mixture become small particles. Generally, the reaction mixture is 8,000 psi and about 1265 kg / cm.
^The device is passed once with a pressure of between ² (18,000 psi). Orifice opening is typically about 50 microns and high pressure is typically about 1000 atmospheres. The multi-passage reduces the average particle size and narrows the range of particle size distribution.

The liquid mixture of the present invention is pumped into the chamber at high speed and pressure when processed in such a liquid jet interaction process. Then the liquid mixture
Sprayed under pressure through multiple elongated nozzles,
Form a plurality of thin sheets of liquid mixture. The thin sheet is then forced to impinge along the common liquid jet interaction front in the zone of liquid. The leading edge of one of the thin sheets can be considered the target against which one or more other sheets collide. Recirculation of at least a portion of the liquid mixed product through the nozzle can be performed to reduce particle size and / or to make particles more uniform.

This liquid jet interaction process produces a relatively small particle size having a higher uniformity than that achieved by prior art ball milling. The particle size can be adjusted by controlling the strength of the above interactions (eg velocity, pressure and temperature). As a result of the particles of the liquid mixture moving relative to each other, effective grinding is possible. The combination of small orifices and very high pressure is such that they pass through the same or different orifices one to about six times to mill the X-form metal-free phthalocyanine particles to an average particle size of less than about 0.6 microns. Must be sufficient. Larger particle sizes tend to produce unstable dispersions. Preferably, the high shear force applied by the multi-step process is about 0.
Average particle size less than 4 microns, more preferably about 0.3
Sufficient to form X-form metal-free phthalocyanine pigment particles having an average particle size of less than micron. The dispersion prepared by this multistage high energy process is stable to sedimentation and can be effectively used to form a charge generating layer on a drum by dip coating.

If desired, the liquid jet interaction process can alternatively include using a single stream of liquid mixture directed to a solid fixed target. As in the multi-flow process described above, the particle size can be adjusted by controlling the strength of interaction (eg, velocity, pressure and temperature). The resulting movement of the particles of the liquid mixture relative to the solid immobilization target allows for effective grinding. The equipment for performing this single-flow step is a commercially available model, eg, from Gaulin Corp in Everett, Massachusetts.

The solids content of the mixture to be ground does not appear to be significant and can be selected from a wide range of concentrations. A Silverson stirrer that applies sufficient high shear in the first processing stage, and a Microfluidics (Microfl) for liquid jet interaction process.
The time to use the uidics ™ grinder is generally between 30 minutes and 1 hour. The concentrated mixture of photoconductive particles and binder solution may be first dispersed and then diluted with another binder solution for coating mixture preparation purposes.

Any suitable technique of applying the treated coating mixture to the substrate to be coated can be utilized. Common coating techniques include dip coating, roll coating, spray coating and rotary atomizers. These coating techniques can be used for a wide range of solids concentrations. Preferably, the solids content is
Between about 2 weight percent and about 8 weight percent, based on the total weight of the dispersion. The expression "solid" means
Refers to the components of the pigment particles and binder of the coating dispersion. These solids concentrations are useful in dip coating, roll coating, spray coating and the like. Generally, more concentrated coating dispersions are preferred for roll coating.

Drying of the deposited coating is oven drying,
It can be carried out by any suitable conventional technique such as infrared radiation drying and air drying.

The active charge transport layer can consist of an activating formulation useful as an additive dispersed in the electrically inactive polymeric material to render it electrically active.
These formulations can be added to polymeric materials that cannot sustain the injection of photogenerated holes from the generating material and cannot transport these holes through themselves. This allows the electrically inactive polymeric material to maintain the injection of photogenerated holes from the generating material and transport these holes through the active layer to discharge the surface charge on the active layer. Can be made. A particularly preferred transport layer for use in one of the two electroactive layers in the multilayer photoreceptor of the present invention is from about 25 percent to about 75 weight percent of at least one charge transport aromatic amine formulation and
And from about 75 to about 25 weight percent aromatic amine soluble polymeric film-forming resin.

The charge transport layer forming mixture preferably comprises an aromatic amine formulation of one or more formulations having the general formula:

[Chemical 3] Here, R ₁ and R ₂ are aromatic groups selected from the group consisting of a substituted or unsubstituted phenyl group, a naphthyl group and a polyphenyl group, and R is a substituted or unsubstituted aryl group, 1 Selected from groups consisting of alkyl groups having from 1 to 18 carbon atoms and cycloaliphatic compounds having from 3 to 18 carbon atoms. This substituent must be a free-form electron withdrawing group such as NO ₂ and CN groups.

As an example of a charge-transporting aromatic amine represented by the above structural formula for a charge-transporting layer capable of maintaining the injection of photo-generated holes in the charge-generating layer and transporting holes through the charge-transporting layer. Is triphenylmethane, bis (4-diethylamine-2-methylphenyl) phenylmethane, 4'-, dispersed in an inert resin binder.
4 "-bis (diethylamino) -2 ', 2" -dimethyltriphenylmethane, and N, N'-bis (alkylphenyl) -1,1'-biphenyl-4,4'-diamine, where alkyl is For example, methyl, ethyl, propyl, n-butyl, etc., N, N′-diphenyl-N, N′-bis (chlorophenyl) -1,1 ′
-Biphenyl-4,4'-diamine, and N, N'-
Diphenyl-N, N'-bis (3 "-methylphenyl)
-(1,1'-biphenyl) -4,4'-diamine and the like.

Any suitable inert resin binder soluble in methylene chloride or other suitable solvent can be used in the process of the present invention. Common inert resin binders soluble in methylene chloride include polycarbonate resins, polyvinylcarbazoles, polyesters, polyarylates, polyacrylates, polyethers and polysulfones. The molecular weight is about 20,000 to about 150,000.
It can be up to 0.

After mixing, any suitable conventional technique can be utilized to apply the charge transport layer coating mixture to the coated or uncoated substrate. Common coating techniques include spraying, dip coating, roll coating and wire wound rod coating. Drying of the deposited coating can be carried out by any suitable conventional technique such as oven drying, infrared radiation drying and air drying.

Generally, the thickness of the hole transport layer is between about 10 and about 50 microns, although thicknesses outside this range can be used. The hole transport layer is an insulating layer to the extent that electrostatic charges on the hole transport layer are not conducted in the absence of irradiation at such a rate as to prevent the formation and retention of an electrostatic latent image thereon. There is a need. Generally, the thickness ratio of the hole transport layer to the charge generating layer is preferably from about 2: 1 to 200 :.
It is maintained up to 1 and in some cases even 400: 1.

The preferred electrically inert resin material is a polycarbonate resin having a molecular weight of about 20,000 to about 150,000, more preferably about 50,000 to about 120,000. The most preferred electrically inactive resin material is poly (4,4'-dipropylidene-diphenylene carbonate) available from General Electric Company as Lexan 145 and having a molecular weight of from about 35,000 to about 40,000. , General Electric from Lexan
Available as 141, about 40,000 to about 45,
Poly (4,4′-isopropylidene-diphenylene carbonate) having a molecular weight of up to 000, Farben
Fabricken Bayer A. G. To Mak
Available as rolon, about 50,000 to about 1
Polycarbonate resins having a molecular weight of up to 20,000, and Mobay Chemical Compa
about 20,000, available as Merlon from ny
It is a polycarbonate resin having a molecular weight of 0 to about 50,000. Methylene chloride solvent is a preferred component of the charge transport layer coating mixture because of its good solubility in all compositions and its low boiling point.

The photoreceptor comprises, for example, a charge generation layer sandwiched between the conductive surface and the above charge transport layer, or a charge transport layer sandwiched between the conductive surface and the charge generation layer. You can

[0040]

【Example】

Example I. A dispersion is prepared by dissolving a film-forming binder of polyvinyl butyral copolymer (B79 available from Monsanto) in cyclohexanone (CXN) solvent, followed by X.
Foam Made by adding metal-free phthalocyanine (xHPc) pigment. The weight ratio of pigment to binder is
68:32 at 4.4 percent solids level.
The dispersion was subjected to vigorous stirring and high shear for 30 minutes using a high speed stirrer (Silverson model # L4R available from Silverson Machines Ltd.). The next step is to obtain a mixture of polyvinyl butyral copolymer, X-form metal-free phthalocyanine and cyclohexanone with a fluid streamline of 560 kg / cm.
Homogenizer (Microfluidics Corporation, Newtown, Mass.).
Microfluidics M available from Corporation.
dl) pumping the feed stream into the chamber through a narrow orifice such as in MF110) to process the dispersion. This is about 200 to 40
Achieved with 6 passes through the homogenizer at a volumetric throughput of 0 ml / min. The average particle size of the milled pigment was 0.27 micron. The charge generating layer coating mixture was applied by a dip coating process in which a 1.5 micron thick nylon coating was coated,
A cylindrical aluminum drum having a diameter of 40 mm and a length of 310 mm is immersed in the charge generation layer coating mixture vertically at a speed of 160 mm / min along a path parallel to the drum axis and then withdrawn therefrom. It was The applied charge generating coating was oven dried at 160 ° C. for 10 minutes to form a layer having a thickness of about 0.2 micron. This coated charge generation layer is then coated with 36 percent N, N'- dissolved in a monochlorobenzene solvent.
Diphenyl-N, N'-bis (3-methylphenyl)-
Dip coated with a charge transfer mixture containing 1,1'-biphenyl-4,4'-diamine and polycarbonate. The applied charge transfer coating is applied for 118 minutes at 118.
Dried in a forced air oven at 0 ° C to form a layer having a thickness of 20 microns.

Example II. A dispersion was prepared by dissolving a film-forming binder of polyvinyl butyral copolymer (B79 available from Monsanto) in a solvent of n-butyl acetate (nBuOAc), followed by X-form metal-free phthalocyanine (xH).
Pc) made by adding a pigment. The pigment to binder weight ratio is 68: 3 at the 4.4 percent solids level.
It was 2. This dispersion is a high speed stirrer (Silver
Son model # L4R) was subjected to strong agitation and high shear for 30 minutes. The dispersion is then subjected to a fluid streamline of a mixture of polyvinyl butyral copolymer, X-foam metal-free phthalocyanine and n-butyl acetate.
It was pumped as a feed stream into the chamber through a narrow orifice so that it would interact at a pressure of 560 kg / cm. This is about 200 to 400 ml / min
Was achieved with 6 passes through the homogenizer. The average particle size of the ground pigment is 0.27
It was micron. The charge generation layer coating mixture was applied by a dip coating process in which a cylindrical aluminum drum 40 mm in diameter and 310 mm in length coated with a 1.5 micron thick nylon coating was used.
At a speed of 0 mm / min, it was immersed vertically in a charge generation layer coating mixture along a path parallel to the drum axis and then withdrawn from it. The applied charge generating coating was dried in an oven at 160 ° C. for 10 minutes,
A layer having a thickness of about 0.2 micron was formed. This coated charge generating layer is then coated with 36 percent N, N'-diphenyl-soluble in monochlorobenzene solvent.
Dip coated with a charge transfer mixture containing N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine and polycarbonate. The applied charge transport coating was dried in a forced air oven at 118 ° C for 55 minutes to form a layer having a thickness of 20 microns.

Example III. The dispersion is a polyvinyl butyral copolymer (B available from Sekisui Chemical Co., Ltd.).
100 grams of a film-forming binder of M-S) was dissolved in 2400 grams of cyclohexanone. The resulting solution was added to a mixture of 246 grams of X-form metal free phthalocyanine and 4,200 grams of cyclohexanone, then the resulting mixture was placed in a horizontal mill having a mill chamber volume of 600 ml for 3 hours. The mixture was ground by circulating the mixture at a flow rate of 300 ml / min. The grinding chamber contains 700 grams of glass beads with a diameter of 1 mm and has a central spindle speed of 2,000.
It was rpm. Cooling was provided by a water jacket surrounding the grinding chamber. The resulting dispersion is then 43
Put 0 gram portion in a glass container, 7,000 rpm
Rotate for 30 minutes at room temperature to remove all supernatant from bottom to top 2.5
It was collected from cm and centrifuged. This step results in a dispersion of pigment having an average particle size of about 0.3 to 0.4 microns. The solution is then filtered,
In order to form the charge generation layer using the dip coating device,
It was further diluted with solvent to a solids content of 3.0 percent. The charge generation layer coating mixture was applied by a dip coating process in which a cylindrical aluminum drum 40 mm in diameter and 310 mm in length coated with a 1.5 micron thick nylon coating was 160 m
At a speed of m / min, it was immersed vertically into the charge generation layer coating mixture along a path parallel to the drum axis and then withdrawn from it. 1 charge generating coating applied
Dry in an oven at 160 ° C. for 0 minutes to give about 0.
A layer having a thickness of 2 microns was formed. This coated charge generation layer is then coated with 36 percent N, N'-diphenyl-N, N 'dissolved in a monochlorobenzene solvent.
Dip coated with a charge transfer mixture containing -bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine and polycarbonate. The applied charge transport coating was dried in a forced air oven at 118 ° C for 55 minutes to form a layer having a thickness of 20 microns.

Example IV. The electrophotographic imaging members prepared as described in Examples I, II and III were prepared by electrically charging them with an electric field of 350 V and electrically discharging them with light having a wavelength of 780 nm. Was inspected.
The photoreceptor was examined for visual defects in the coating, i.e., marbled or fine line structures in the charge generation layer. The results are shown in the table below.

[Table 1] The expressions shown in Table 1 are defined as follows. V ₀
Is the surface potential at which the photoreceptor is charged and is measured at the probe 0.16 seconds after charging. V
_LOW is the surface potential after exposure to 780 nm light with an intensity of 3 ergs / cm. % Dark decay is the loss of surface potential in dark color expressed as a percentage of V ₀ and is measured between 0.16 and 0.42 seconds after charging. By this comparison, electrical properties such as sensitivity as measured by V _LoW and percent dark decay are:
It is improved in a multi-stage high shear force dispersion process and it is demonstrated that marble pattern defects are prevented in this process using cyclohexanone rather than n-butyl acetate.

Example V. A vanadyl phthalocyanine dispersion prepared as described in Example I, but with a pigment to binder weight ratio of 35:65 was applied to an aluminum drum as described in Example I. Was done. Immersion under these conditions failed to produce a charge generating layer of sufficient density for electrical inspection. The results show that the multi-step fast shear / homogenization process of the present invention cannot be effectively used for metal phthalocyanines such as vanadyl phthalocyanine.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location // C08F 216/06 MKV 216/38 MLC C08L 29/14 LHA (72) Inventor Richard H. Nealy United States New York 14526 Penfield Coachman Drive 59

Claims (3)

[Claims] 1. An X-form metal-free in solution of a solvent consisting essentially of a ketone having a boiling point between 75 ° C. and about 160 ° C. and a film-forming polymer consisting essentially of a polymer represented by the general formula: Providing a mixture consisting of a pigment consisting essentially of phthalocyanine particles, and Where x is a number such that the polyvinyl butyral component is between about 50 and about 75 mole percent and y is such a number that the polyvinyl alcohol component is between about 12 and about 50 mole percent. , And z are numbers such that the polyvinyl acetate component is a mole percent between about 0 and 15 and a high shear force is applied to the mixture to reduce all of the X-form metal-free phthalocyanine particles to about 2 Substantially milling to an average size of less than micron, forming the mixture into at least one stream, ejecting the stream from at least one nozzle at high pressure and high velocity, the X-form metal-free phthalocyanine particles Particle size of about .0 dispersed in a solution of the solvent and the film-forming polymer.
Impinging the jet stream with a target with sufficient force to break up to an average size of less than 6 microns; providing a substrate to be coated; Applying metal phthalocyanine particles to the substrate to form a coating; drying the coating to substantially remove all of the cyclohexanone solvent to form a dried charge generating layer; A method of manufacturing an electrophotographic imaging member comprising the step of forming a transfer layer. 2. The mixture is formed into at least two streams, each of which is ejected from at least one nozzle at high pressure and high velocity, and at least one of the streams serves as the target. The method for manufacturing an electrophotographic imaging member according to claim 1. 3. The method for manufacturing an electrophotographic imaging member according to claim 1, wherein the target object is a fixed solid object.