US3241958A - Electrophotographic recording members and processes of preparing same - Google Patents

Electrophotographic recording members and processes of preparing same Download PDF

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US3241958A
US3241958A US241008A US24100862A US3241958A US 3241958 A US3241958 A US 3241958A US 241008 A US241008 A US 241008A US 24100862 A US24100862 A US 24100862A US 3241958 A US3241958 A US 3241958A
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weight
coat
photo
substrate
coating layer
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US241008A
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Bornarth Dennis Michael
Berka Roman
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AB Dick Co
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Multigraphics Inc
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Priority to BE639812D priority Critical patent/BE639812A/xx
Priority to NL300364D priority patent/NL300364A/xx
Application filed by Multigraphics Inc filed Critical Multigraphics Inc
Priority to US241008A priority patent/US3241958A/en
Priority to DEP1272A priority patent/DE1272123B/de
Priority to GB43884/63A priority patent/GB1059137A/en
Priority to NL63300364A priority patent/NL139211B/xx
Priority to FR955588A priority patent/FR1388789A/fr
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/142—Inert intermediate layers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers

Definitions

  • This invention relates to electrophotographic recording members and to processes of producing such members. More particularly this invention relates to electrophotographic recording members useful for producing positive reproductions and which can also be used advantageously in reversal electrophotographic printing procedures.
  • a reversal image is produced by projecting light through the nega tive onto a charged photo-conductive recording member to form a latent electrostatic image, commonly referred to as a reversal image.
  • This image is developed by the application of electroscopic developed powder by any of several well known techniques, such as cascade developers, magnetic brush developers, and liquid developers, and the developer powder is thereafter fixed to form the finished copy.
  • the latent electrostatic image is produced by exposing to light the charge in the non-image or background areas, thus discharging these areas in proportion to the light intensity.
  • the image areas are not exposed to light and hence retain their original charge.
  • the electroscopic developer powder applied bears a charge of a polarity opposite to that on the image areas and is thus attracted to and held onto these areas.
  • the charge in the image areas is exposed to light leaving the non-image or background areas with their original charge and electroscopic developer powder is applied having a charge of a polarity the same as that on the nonimage areas.
  • the charged non-image areas thus repel the developer powder onto the image areas, leaving the nonimage or background areas free of the developer powder.
  • the non-image areas retain a high residual charge, after exposure, of the image areas, at least during the development so that the developer powder will be deposited on the image areas leaving the nonimage or background areas free of developer powder.
  • Known elect-rophotographic recording members have employed precoats between the substrate, usually paper but which can be cloth, film, metal foil or other suitable substrate, and the top coating layer of insulating film forming resin containing the photo-conductor particles embedded therein, to increase the electrical conductivity of the recording member when the charged member is exposed to light.
  • Increasing the conductivity invariably results in an increase in the dark decay properties of the recording members.
  • the rate at which the charge is dissipated in darkness is referred to herein as the dark decay of the recording member.
  • Electrophotographic copies, and particularly those made by reversal printing, as hereinabove disclosed are frequently use as lithographic masters to produce multiple copies from the electrophotographic copy.
  • To condition the electrophotographic copy for use as a lithographic master it is the practise to apply a so-called wetout solution to the electrophotographic copy to render the non-image areas hydrophilic, the image areas being hydrophobic due to the use of a hydrophobic resin developer powder.
  • the reversal image be of high density to provide a good ink receptive base.
  • Such reversal images of high density cannot be obtained employing heretofore known electrophotographic recording members having a high dark decay as above noted, because the non-image areas during the interval between exposure and development lose too much of their charge.
  • the surface photo-conductive layer be uniform in composition and be capable of receiving an adequate electrostatic charge say at least 400 volts and desirably from 400 to 800 volts when charged by a corona discharge from a 6200 volt D.C. source.
  • Still another object of this invention is to provide a process of producing such recording members.
  • the electrophotographic recording members embodying this invention comprise a substrate, which can be any of the known substrates used, such as electrically conductive paper, including high wet strength paper of 3 to 6 mils thickness and having, if desired, a seal coat on its undersurface, cloth, plastic film including cellophane, metallic foils, e.g., aluminum or copper foils, and a precoat on the top face of this substrate, which precoat consists essentially of the reaction product of a water soluble aminoplast precondensate and a film forming polymeric material having at least one reactive carboxyl or hydroxyl group which reaction product is insoluble in water and in the organic solvent, usually toluene, employed for the film forming resin constituent of the top coat.
  • a substrate which can be any of the known substrates used, such as electrically conductive paper, including high wet strength paper of 3 to 6 mils thickness and having, if desired, a seal coat on its undersurface, cloth, plastic film including cellophane, metallic foils, e.g.
  • This precoat completely covers the face of the substrate and has a relatively high electrical resistivity, at least 10 ohms/ cm., preferably from 10 to 10 ohms/cm.
  • the photoconductive layer or top coat covers this precoat layer or film.
  • the photo-conductive layer consists essentially of a homogeneous mixture of film forming resin containing the photo-conductor particles which can be any known photo-conductor such as the oxides of zinc, antimony, aluminum, bismuth, cadmium, mercury, molybdenum, and lead; the iodides, selenides, sulfides or tellurides of these metals; selenium; arsenic trisulfide; lead chromate and cadmium arsenide.
  • the preferred photo-conductor is zinc oxide such, for example, as the photo-conductive zinc oxide sold by the New Jersey Zinc Co., as Florence Green Seal 8.
  • the preferred pre-coat is the reaction product of watersoluble aminoplast precondensate, such for example as melamine formaldehyde or urea-formaldehyde precondensate and a film forming polymeric material produced by polymerization of ethylenically unsaturated monomer or monomers, which polymeric material contains reactive carboxyl or hydroxyl groups, applied to the substrate in an aqueous medium, and reacted in the proportions of from 1 to 5 parts by weight of polymeric solids to 1 part by weight of aminoplast solids at a temperature of from 250 to 360 F.
  • watersoluble aminoplast precondensate such for example as melamine formaldehyde or urea-formaldehyde precondensate
  • a film forming polymeric material produced by polymerization of ethylenically unsaturated monomer or monomers, which polymeric material contains reactive carboxyl or hydroxyl groups
  • polymeric materials which can be reacted with the water-soluble aminoplast precondensate are interpolymers of styrene, hexylacrylate, acrylonitrile and methacrylic acid disclosed in US. Patent 2,767,153, sold by the Monsanto Chemical Co., under their trade name Lytron 680; polyvinyl alcohol; carboxylated styrene maleic anhydride coplymers; carboxylated ethylene maleic anhydride copolymers; hydroxyethyl cellulose; and crotonic acid vinyl acetate copolymers.
  • the aminoplast precondensate can be any of the watersoluble aminoplasts such as dimethylol melamine, dimethyl trimethylol melamine, trimethylol melamine, tetramethylol melamine, tetramethyl pentamethylol melamine,
  • tetramethyl hexamethylol melamine pentamethyl pentamethylol melamine, pentamethyl hexamethylol melamine, other alkylated melamine formaldehyde resins, or mixtures of such resins, urea formaldehyde, aniline formaldehyde, thiourea formaldehyde, and cyanamide formaldehyde.
  • the recording members are prepared by coating the substrate, preferably in web form, with an aqueous coating composition containing from 60 to by weight of water, having dissolved therein the aminoplast precondensate and the polymeric material, when a water soluble polymeric material is used.
  • an aqueous coating composition containing from 60 to by weight of water, having dissolved therein the aminoplast precondensate and the polymeric material, when a water soluble polymeric material is used.
  • the latex is mixed with the solution of aminoplast precondensate.
  • this coating composition can contain a small amount of a stabilizing agent to prevent premature reaction of the aminoplast and polymeric material.
  • a plasticizer or fiexibilizing agent such as polyvinyl acetate which imparts greater flexibility to the precoat, is also incorporated.
  • the coating composition is applied to the substrate using any known coating equipment such as spray or roll type coaters which apply the coating to one surface of the substrate in amount to provide a layer or film, which when dry weighs about 4 pounds per 3,000 square feet of substrate.
  • the coating composition can be applied employing immersion type coating equipment.
  • the coated substrate is passed through a curing oven, e.g., a hot air drying chamber at a temperature of from 250 to 360 F., preferably about 350 F., for a residence time of from 30 seconds to 5 minutes.
  • Reaction takes place between the aminoplast and the polymeric material forming a continuous uniform fil'm securely bonded to the substrate which film is water-insoluble and insoluble in the organic solvent for the resin or resins employed in the top coat, of high electrical resistivity and surprisingly imparts to the final product improved photo-conductive and dark decay properties.
  • the top coat is applied to the pre-coat using any known coating equipment.
  • a homogeneous dispersion of the photo-conductor particles in a solution of the resinous film forming vehicle such for example as the silicone resins of the alkyl aryl type (GE. No. 81,182 or Sr-82 or Dow-Corning No. 803) or styrenebutadiene copolymers in an organic solvent, e.'g., toluene or trichloroethylene, the ratio of photo-conductor particles to resin being from 1 to l to 5 to 1.
  • the top coat may be formed by applying a dispersion containing from 35% to 50% by weight of photoconductor particles, such as zinc oxide, from 10% to 30%, preferably 25% to 30%, by weight of resin and from 35% to 55% by weight of solvent.
  • the coated substrate is passed through a drying oven maintained at a temperature of 200 F. to 250 F. for a residence time of from 30 seconds to 5 minutes, to remove the volatiles, i.e., the solvent; the solvent can be otherwise evaporated.
  • the resultant top coat contains from 35 to 50 parts by weight of the photo-conductor particles such as zinc oxide and from 10 to 30 preferably 25 to 30 parts by weight of resin.
  • Typical formulations on a weight basis, useful in producing the pre-coat are:
  • the substrate is a commercial bleached sulfite paper.
  • Example I The pre-coat formulation is: Percent Dimethyl-trimethylol-melamine resin precondensate (Pa-rez 613) 13.5 Water 70.5 Ammonium hydroxide 0.5 Styrene-hexyl acrylate-acrylonitrile-methacrylic acid (Lytron 680) 16.0
  • the dimethyl-trimethylol-melamine resin is dissolved in the water.
  • the ammonium hydroxide is then added; it serves as a stabilizing agent to prevent the premature reaction between the resin with the styrene-hexyl aorylateacrylonitrile-methacrylic acid polymeric material, which is thereafter added as a latex or dispersion.
  • the mixture is stirred until it is homogeneous requiring about 5 to 7 minutes.
  • the ratio of aminoplast solids to solid carboxylate inter-polymer in the resultant dispersion is 1 to 1.20; the pre-coat dispersion has a viscosity of 16-20 centipoise at room temperature.
  • the dispersion is coated on a continuous web of the paper substrate at a rate which gives a final dry coating 'weight of 5 lbs. per 3,000 sq. ft.
  • the coated web is passed through a forced hot air drying chamber maintained at 350 F., the residence time in this oven is about 1 minute. During this time the resin and polymer react and are cured into a continuous uniform film securely bonded to the paper.
  • the photo-conductive layer having the following composition:
  • the silicone resin is mixed with a portion of the toluene until it is completely dissolved. The remainder of the solvent is added gradually while stirring the batch. Once the zinc oxide is uniformly dispersed and the mixture is homogeneous, which may require from 2-24 hours ball milling, the solution is applied at room temperature to the pro-coated side of the paper to yield a final dry coating weight of 20 lbs. per 3,000 sq. ft.
  • the thus coated paper is passed through a forced hot air drying chamber which is maintained at a temperature in the range of 200 F. to 250 F. in order to remove the volatiles (eifected in 6 about 1 minute) and to lay down a uniform photo-coriductive layer.
  • Example II The pre-coat formulation is: Percent Dimethyl-trimethylol-melamine 1.6 Water 85.5
  • the weight ratio of polyvinyl alcoholthe polymer having the reactive hydroxyl functional groups, as solids, to the weight of solids of aminoplast is 4:1.
  • the polyvinyl alcohol is added under constant stirring to the water heated to a temperature of F. to 200 F. Stirring continues until a clear, homogeneous solution results which is then allowed to cool to room temperature.
  • the polyvinyl acetate copolymer is then added to the cooled solution while agitating the mixture.
  • the completed formulation is stirred for an additional 5 minutes after addition of all of the polyvinyl acetate copolymer and the resultant composition applied to the paper as in Example I.
  • a photo-conductive layer is then applied having the following composition:
  • Example III The pre-coat formulation is:
  • This dispersion is applied to the paper, the coated paper cured and the top coat applied thereto, all as in Example I.
  • Example IV This example differs from Example II in the substitution of hydroxyethyl cellulose (Natrasol 250, Hercules Powder Co.) for the polyvinyl alcohol, employing substantially the same amount by weight of the hydroxyethyl cellulose as the polyvinyl alcohol.
  • the procedure followed in curing the precoat and applying and curing the top coat is the same as in Example I.
  • Example V This example differs from Example I chiefly in the substitution of the crotonic acid vinyl acetate copolymer (Gelva C3, Shawinigan Chemical Co.) in amount approximately the same as the amount of interpolymer used in Example I. All other conditions are the same as in Example I.
  • the crotonic acid vinyl acetate copolymer (Gelva C3, Shawinigan Chemical Co.) in amount approximately the same as the amount of interpolymer used in Example I. All other conditions are the same as in Example I.
  • Example VI This example differs from Example I only in the utilization of a formulation for the pre-coat, containing a ratio of solids of aminoplast to the carboxylated interpolymer of approximately 1 to 5; the formulation for the pre-coat used in Example VI contained 5.0% by weight of the aminoplast solids and 24.0% by weight of polymer (Lytron 680) solids. All other conditions are substantially the same.
  • Example VII This example differs from Example III only in the substitution of a carboxylated copolymer of styrene and maleic anhydride for the copolymer used in Example III.
  • the amount of the respective copolymers are approximately the same in both examples.
  • FIGURE 1 is a vertical section through an electrophotographic recording member embodying this invention; this figure shows the thickness of the paper and the coating layers thereon enlarged as compared with their actual thicknesses, for the sake of clarity of illustration; and
  • FIGURE 2 is a plot showing dark decay curves of the recording members of the examples of this invention, and for comparative purposes two other recording members not embodying the present invention.
  • the substrate preferably paper such as a commercial grade of paper which has good electrical conductivity properties.
  • substrate 10 if desired, has a base seal coat 11 which can be of the same composition as the pre-coat 12 on the opposite side of the substrate 10.
  • the pre-coat 12, as hereinabove disclosed, is a water-laid, water-insoluble, organic-solvent-insoluble reaction product of the aminoplast precondensate with the polymeric material having reactive carboxyl or hydroxyl groups, which layer 12 is of relatively high electrical resistivity, i.e., has a resistivity of at least about 10 and desirably within the range of 10 to 10 ohms/cm.
  • the precoat of Example I has a resistivity of l.52 l0 ohms/cm; and those of Examples II and III have a resistivity of l.27 10 ohms/cm.
  • the organic solvent laid photo-conductive layer 13 consisting essentially of the photo-conductive particles 14 uniformly distributed throughout and embedded in the resin binder which with the photo-conductive particles forms the layer 13.
  • the pre-coat layer 12 renders the paper or fibrous substrate 10 resistant to solvent penetration, i.e., prevents penetration into the substrate by the toluene solvent employed as the solvent medium for the film forming resin binder of layer 13, thus resulting in the formation of a smooth uniform photo-conductive layer 13. It also acts as a barrier layer to inhibit moisture or chemical migration through the substrate into the photo-conductive layer 13, and thus results in an electrophotographic recording member of improved properties, particularly from the standpoint of ability to receive a charge at a relatively high saturation level and its dark decay properties.
  • the electrophotographic recording member of this invention has a combination of desirable properties and is unique and outstanding particularly for use as a recording member in reversal techniques and for the production of copies which are employed as lithographic masters.
  • the recording members have relatively high saturation levels for electrostatic charges applied thereto by corona discharge at a given voltage.
  • their saturation level when charged by corona discharge from a 6200 volt D.C. source of a negative potential with respect to ground, is from 600 to 800 volts, as shown in FIG- URE 2.
  • the dark decay properties of the recording members of the examples are shown in FIGURE 2.
  • the curves identified by the legends Ex. I, Ex. II, Ex. III, and Ex. IV-VII are the dark decay curves for the recording members of the respective examples. These curves were obtained by measuring the voltage of the respective recording members (1) at saturation level and when charged in all cases with a corona discharge at 6200 volts from a DC. source at negative potential relative to ground, and (2) at periodic intervals thereafter by means of a suitable probe wrich picked up the charge level at the surface of the respective recording members and fed the resulting signals into a calibrated oscilloscope. The voltage levels of the respective recording members were read from the oscilloscope and curves were made from the data thus obtained.
  • the curve marked comparative curve A is the dark decay curve obtained as hereinabove described on a recording member made with the same paper base as used in the examples having the same top coat and having a pre-coat which differs from that employed in Example II only in the elimination of the dimethylol-trimethylol-rnelamine and the polyvinyl acetate copolymer from the formulation for the precoat of Example II.
  • the pre-coat of the recording member the dark decay characteristics of which are shown by curve A, differs from that of Example II in that the precoat consists of polyvinyl alcohol alone (applied in a water solution having a concentration of about 6.5%) and not the reaction product of polyvinyl alcohol and dimethylol-trimethylol-melamine.
  • the curve marked comparative curve B is a dark decay curve of an electrophotographic recording member made with the same paper substrate, having a photo-conductive layer of the same composition, and produced in the same manner as the examples, differing from the recording members of the examples only in the elimination of the pre-coat.
  • Such electrophotographic recording elements are typical of present available commercial products.
  • comparative product B which is typical of currently known commercial electrophotographic recording members having the photo-conductive insulating layer consisting of silicone resin and zinc oxide photo-conductor FORMULATION 2 Dimethyl-trimethylol-melamine 1.0-3 .0 Water 65.0-86.0
  • the substrate is a commercial bleached sulfite paper.
  • Example I The pre-coat formulation is: Percent Dimethyl-trimethylol-melamine resin precondensate (Parez 613) 13.5 Water 70.5 Ammonium hydroxide 0.5 Styrene-hexyl acrylate-acrylonitrile-methacrylic acid (Lytron 680) 16.0
  • the dimethyl-trimethylol-melamine resin is dissolved in the water.
  • the ammonium hydroxide is then added; it serves as a stabilizing agent to prevent the premature reaction between the resin with the styrene-hexyl aorylateacrylonitrile-methacrylic acid polymeric material, which is thereafter added as a latex or dispersion.
  • the mixture is stirred until it is homogeneous requiring about 5 to 7 minutes.
  • the ratio of aminoplast solids to solid carboxylate inter-polymer in the resultant dispersion is 1 to 1.20; the pre-coat dispersion has a viscosity of 16-20 .centipoise at room temperature.
  • the dispersion is coated on a continuous web of the paper substrate at a rate which gives a final dry coating weight of 5 lbs. per 3,000 sq. ft. through a forced hot air drying chamber maintained at 35 0 E, the residence time in this oven is about 1 minute. During this time the resin and polymer react and are cured into a continuous uniform film securely bonded to the paper.
  • the photo-conductive layer having the following composition:
  • the silicone resin is mixed with a portion of the toluene until it is completely dissolved. The remainder of the solvent is added gradually while stirring the batch. Once the zinc oxide is uniformly dispersed and the mixture is homogeneous, which may require from 2-24 hours ball milling, the solution is applied at room temperature to the pre-coated side of the paper to yield a final dry coating weight of 20 lbs. per 3,000 sq. ft.
  • the thus coated paper is passed through a forced hot air drying chamber which is maintained at a temperature in the range of 200 F. to 250 F. in order to remove the volatiles (elfected in The coated web is passed a about 1 minute) and to lay down a uniform photo-con ductive layer.
  • Example II The pre-coa-t formulation is: Percent Dimethyl-trimethy-lol-melamine 1.6 Water 85.5
  • the weight ratio of polyvinyl alcohol-the polymer having the reactive hydroxyl functional groups, as solids, to the weight of solids of aminoplast is 4:1.
  • the polyvinyl alcohol is added under constant stirring to the water heated to a temperature of F. to 200 F. Stirring continues until a clear, homogeneous solution results which is then allowed to cool to room temperature.
  • the polyvinyl acetate copolymer is then added to the cooled solution while agitating the mixture.
  • the completed formulation is stirred for an additional 5 minutes after addition of all of the polyvinyl acetate copolymer and the resultant composition applied to the paper as in Example I.
  • a photo-conductive layer is then applied having the following composition:
  • Example III The pre-coat formulation is:
  • This dispersion is applied to the paper, the coated paper cured and the top coat applied thereto, all as in Example I.
  • Example IV This example differs from Example 11 in the substitution of hydroxyethyl cellulose (Natrasol 250, Hercules Powder Co.) for the polyvinyl alcohol, employing substantially the same amount by weight of the hydroxyethyl cellulose as the polyvinyl alcohol.
  • the procedure followed in curing the precoat and applying and curing the top coat is the same as in Example I.
  • Example V This example differs from Example I chiefly in the substitution of the crotonic acid vinyl acetate copolymer (Gelva C-3, Shawinigan Chemical Co.) in amount approximately the same as the amount of interpolymer used in Example I. All other conditions are the same as in Example 1.
  • the crotonic acid vinyl acetate copolymer (Gelva C-3, Shawinigan Chemical Co.) in amount approximately the same as the amount of interpolymer used in Example I. All other conditions are the same as in Example 1.
  • Example VI This example differs from Example I only in the utilization of a formulation for the pre-coat, containing a ratio of solids of aminoplast to the carboxylated interpolymer of approximately 1 to 5; the formulation for the pre-coat used in Example VI contained 5.0% by weight of the aminoplast solids and 24.0% by weight of polymer (Lytron 680) solids. All other conditions are substantially the same.
  • Example VII This example differs from Example III only in the substitution of a carboxylated copolymer of styrene and maleic anhydride for the copolymer used in Example 111.
  • the amount of the respective copolymers are approximately the same in both examples.
  • FIGURE 1 is a vertical section through an electrophotographic recording member embodying this invention; this figure shows the thickness of the paper and the coating layers thereon enlarged as compared with their actual thicknesses, for the sake of clarity of illustration; and
  • FIGURE 2 is a plot showing dark decay curves of the recording members of the examples of this invention, and for comparative purposes two other recording members not embodying the present invention.
  • the substrate preferably paper such as a commercial grade of paper which has good electrical conductivity properties.
  • substrate 10 if desired, has a base seal coat 11 which can be of the same composition as the pre-coat 12 on the opposite side of the substrate 10.
  • the pre-coat 12, as hereinabove disclosed, is a water-laid, Water-insoluble, organic-solvent-insoluble reaction product of the aminoplast precondensate with the polymeric material having reactive carboxyl or hydroxyl groups, which layer 12 is of relatively high electrical resistivity, i.e., has a resistivity of at least about 10 and desirably within the range of 10 to 10 ohms/cm.
  • the precoat of Example I has a resistivity of 1.52 10 ohms/cm; and those of Examples II and III have a resistivity of 1.27 l0 ohms/cm.
  • the organic solvent laid photo-conductive layer 13 consisting essentially of the photo-conductive particles 14 uniformly distributed throughout and embedded in the resin binder which with the photo-conductive particles forms the layer 13.
  • the pre-coat layer 12 renders the paper or fibrous substrate 10 resistant to solvent penetration, i.e., prevents penetration into the substrate by the toluene solvent employed as the solvent medium for the film forming resin binder of layer 13, thus resulting in the formation of a smooth uniform photo-conductive layer 13. It also acts as a barrier layer to inhibit moisture or chemical migration through the substrate into the photo-conductive layer 13, and thus results in an electrophotographic recording member of improved properties, particularly from the standpoint of ability to receive a charge at a relatively high saturation level and its dark decay properties.
  • the electrophotographic recording member of this invention has a combination of desirable properties and is unique and outstanding particularly for use as a recording member in reversal techniques and for the production of copies which are employed as lithographic masters.
  • the recording members have relatively high saturation levels for electrostatic charges applied thereto by corona discharge at a given voltage.
  • their saturation level when charged by corona discharge from a 6200 volt D.C. source of a negative potential with respect to ground, is from 600 to 800 volts, as shown in FIG- URE 2.
  • the dark decay properties of the recording members of the examples are shown in FIGURE 2.
  • the curves identified by the legends Ex. I, Ex. II, Ex. III, and Ex. IV-VII are the dark decay curves for the recording members of the respective examples. These curves were obtained by measuring the voltage of the respective recording members (1) at saturation level and when charged in all cases with a corona discharge at 6200 volts from a DC. source at negative potential relative to ground, and (2) at periodic intervals thereafter by means of a suitable probe wrich picked up the charge level at the surface of the respective recording members and fed the resulting signals into a calibrated oscilloscope. The voltage levels of the respective recording members were read from the oscilloscope and curves were made from the data thus obtained.
  • the curve marked comparative curve A is the dark decay curve obtained as hereinabove described on a recording member made with the same paper base as used in the examples having the same top coat and having a pre-coat which differs from that employed in Example II only in the elimination of the dimethylol-trimethylol-melamine and the polyvinyl acetate copolymer from the formulation for the precoat of Example II.
  • the pre-coat of the recording member the dark decay characteristics of which are shown by curve A, differs from that of Example II in that the precoat consists of polyvinyl alcohol alone (applied in a water solution having a concentration of about 6.5%) and not the reaction product of polyvinyl alcohol and dimethylol-trimethylol-rnelamine.
  • the curve marked comparative curve B is a dark decay curve of an electrophotographic recording member made with the same paper substrate, having a photo-conductive layer of the same composition, and produced in the same manner as the examples, differing from the recording members of the examples only in the elimination of the pre-coat.
  • Such electrophotographic recording elements are typical of present available commercial products.
  • comparative product B which is typical of currently known commercial electrophotographic recording members having the photo-conductive insulating layer consisting of silicone resin and zinc oxide photo-conductor particles
  • the recording member loses more than half its charge in seconds and loses almost the entire charge in from about 35 to 40 seconds.
  • the comparative recording member A having a polyvinyl alcohol precoat while superior to product B is markedly inferior to the recording members of this invention in that the recording member A loses in 30 to 40 seconds so much of the original charge that the residual voltage is not adequate for the production of good copies by reversal techniques.
  • the rate of dark decay is relatively slow and the products retain charges well above 400 volts after 30-40 seconds. For dense images produced by reversal procedures it is important that the charge in the non-image areas be at least 400 volts during development.
  • This table also contains data on the density of the developed electrostatic images produced on the recording members of the examples as well as on the comparative recording members A and B. These density determinations were made using a standard photovoltmeter. The results are truly comparative because the same equipment and techniques Were used in obtaining the values for all recording members, all of which were subjected to charging, exposing, and developing with the same developer powder under the same conditions and in the same equipment.
  • the value 2 in Photovolts units represents standard black; values above 1 are considered excellent for images produced with the developer powder employed in these comparative tests. Zero is the value for white.
  • the recording members of this invention show a truly surprising improvement in density of the developed images as compared with the recording members A and B.
  • An electrophotographic recording member consisting essentially of a substrate having thereon a coating layer covering and bonded to the face of said substrate, said coating layer consisting essentially of the waterinsoluble reaction product of a water-soluble aminoplast precondensate and a polymeric film-forming material having a reactive group from the group consisting of hydroxyl groups and carboxyl groups, and a top coating layer bonded to said first-mentioned coating layer, said top coating layer consisting essentially of photo-conductor particles uniformly distributed throughout an electrically insulating film-forming resinous binder.
  • An electrophotographic recording member consisting essentially of a paper substrate having thereon a water-laid coating layer covering and bonded to the face of the substrate, said coating layer consisting essentially of a water-insoluble reaction product of a watersoluble amino-plast precondensate and a polymeric film-forming material having a reactive group from the group consisting of hydroxyl and carboxyl groups and a top coating layer bonded to said first mentioned coating layer, said top coating layer consisting essentially of Zinc oxide photoconductor particles uniformly distributed throughout an electrically insulating film-forming resin binder for said zinc oxide particles, said binder bonding the said top coating layer directly to the first-mentioned coating layer.
  • An electrophotographic recording member consisting essentially of a paper substrate having thereon a waterlaid coating layer covering and bonded to the face of said substrate, said coating layer consisting essentially of the reaction product of dimethyl-trimethylol-melamine with an interpolymer of styrene-hexyl acrylate-acrylonitrile and methacrylic acid in the proportions of approximately 1 part by weight of melamine resin to 1.2 parts by weight of said interpolymer and a top coating layer bonded to said first-mentioned coating layer, said top coating layer consisting essentially of zinc oxide photo-conductor particles uniformly distributed throughout an electrically insulating film-forming resin binder for said zinc oxide particles, said binder bonding the said top coating layer directly to the first-mentioned coating.
  • An electrophotographic recording member consisting essentially of a paper substrate having thereon a waterlaid coating layer covering and bonded to the face of said substrate, said coating layer consisting essentially of the reaction product of dimethyl-trimethylol-melamine with polyvinyl alcohol in the proportions of approximately 1 part by weight of aminoplast to 4 parts by Weight of said polyvinyl alcohol and a top coating layer bonded to said first-mentioned coating layer, said top coating layer consisting essentially of zinc oxide photo-conductor particles in an electrically insulating film-forming resin binder in the proportions of approximately 10 to 30 parts by weight of resin to from 35 to 50 parts by weight of zinc oxide.
  • An electrophotographic recording member consisting essentially of a paper substrate having thereon a waterlaid coating layer covering and bonded to the face of the substrate, said coating layer consisting essentially of the reaction product of urea formaldehyde precondensate with a carboxylated ethylene maleic anhydride copolymer in the proportions of approximately 1 part by weight of urea formaldehyde to 4 parts by weight of said copolymer and a top coating layer bonded to said first-mentioned coating layer, said top coating layer consisting essentially of zinc oxide photo-conductor particles in an electrically insulating film-forming resin binder in the proportions of approximately 10 to 30 parts by Weight of resin to from 35 to 50 parts by weight of zinc oxide.
  • An electrophotographic recording member consisting essentially of a paper substrate having thereon a water-laid coating layer covering and bonded to the face of said substrate, said coating layer consisting essentially of the reaction product of dimethyl-trimethylol-melamine with hydroxyethyl cellulose in the proportions of approximately 1 part by weight of said melamine resin to l to 5 parts by Weight of said hydroxyethyl cellulose and a top coating layer bonded to said first-mentioned coating layer, said top coating layer consisting essentially of zinc oxide photo-conductor particles in a film-forming resin binder in the proportions of approximately to 30 parts by weight of resin to from 35 to 50 parts by weight of zinc oxide.
  • An electrophotographic recording member consisting essentially of a paper substrate having thereon a water-laid coating layer covering and bonded to the face of said substrate, said coating layer consisting essentially of the reaction product of dimethyl-trimethylol-melamine with an interpolymer of styrene-hexyl acrylate-acrylonitrile and methacrylic acid in the proportions of approximately 1 part by weight of said melamine to 1 to 5 parts by weight of said interpolymer and a top coating layer bonded to said first-mentioned coating layer, said top coating layer consisting essentially of zinc oxide photoconductor particles in a film-forming resin binder in the proportions of approximately 10 to 30 par-ts by weight of resin to from 35 to 50 parts by weight of zinc oxide.
  • a process of producing electrophotographic recording members which comprises coating a substrate with an aqueous coating composition containing a watersoluble aminoplast precondensate and a film-forming polymeric material having a reactive group from the group consisting of hydroxyl and carboxyl groups, heating the thus coated substrate to react said aminoplast precondensate and the polymeric material thus forming a precoat of high electrical resistivity which is water-insoluble bonded to the face of said substrate, thereafter applying to said precoa't a top coat consisting essentially of photoconductor particles, a film-forming resinous binder for said photo-conductor particles and a volatile solvent for said resinous binder, and evaporating to remove the solvent and bond said topcoat to said pre-coat.
  • a process of producing electrophotographic recording members which comprises coating a paper base with an aqueous coating composition containing dissolved in the aqueous medium an aminoplast precondensate and also containing a film-forming polymeric material produced by polymerization of ethylenically unsaturated monomers, said polymeric material having reactive groups from the group consisting of hydroxyl and carboxyl groups, heating the thus coated paper base to react said aminoplast precondensate and the polymeric material to form a pre-coat of high electrical resistivity which is waterinsoluble, and thereafter applying to said pre-coat a top coat consisting essentially of zinc oxide photo-conductor particles, a film-forming resinous binder for said photoconductor particles and a solvent, and heating the resultant coated material to a temperature of from 200 F. to 250 F. for from 30 seconds to 5 minutes to produce a photo-conductive topcoat bonded to said pre-coat.
  • a process of producing electrophotographic recording members which comprises coating a paper base with an aqueous coating composition containing dissolved in the aqueous medium a melamine formaldehyde resin precondensate and also containing a film-forming polymeric material produced by polymerization of ethylenically unsaturated monomers, said polymeric material having reactive groups from the group consisting of hydroxyl and carboxyl groups, heating the thus coated substrate to a temperature of from 250 F. to 360 F.
  • the process of producing electrophotographic recording members which comprises coating a web of paper with a coating composition consisting essentially of from 5% to 15% by weight of 'dimethyl-trimethylol melamine, from 10% to 25% by Weight of a styrenehexyl acrylate acrylonitrile, methacrylic acid interpolymer, a small amount of ammonium hydroxide, and the rest being substantially entirely water, subjecting the thus coated web to a temperature of from 250 F. to 360 F.
  • a coating composition consisting essentially of from 5% to 15% by weight of 'dimethyl-trimethylol melamine, from 10% to 25% by Weight of a styrenehexyl acrylate acrylonitrile, methacrylic acid interpolymer, a small amount of ammonium hydroxide, and the rest being substantially entirely water, subjecting the thus coated web to a temperature of from 250 F. to 360 F.
  • a coating composition consisting essentially of from 35% to 50% by weight of photo-conductive zinc oxide particles, from 35% to 55% by weight of solvent and from 10% to 30% by weight of insulating resinous binder, and subjecting the thus coated web to a temperature of from 200 F. to 250 F. for from 30 seconds to 5 minutes to eflect removal of the solvent.
  • a process of producing electrophotographic recording members which comprises coating a web of paper with a coating composition consisting essentially of from 1% to 3% by Weight of dimethyl-trimethylol melamine, from 5% to 10% by weight of a polyvinyl alcohol, from 5% to 10% by weight of polyvinyl acetate and the rest being substantially entirely water, subjecting the thus coated web to a temperature of from 250 F. to 360 F. for a residence time of from 30 seconds to 5 minutes, thereafter applying thereto a coating composition consisting essentially of from 35% to 50% by weight of photo-conductive zinc oxide particles, from 35 to 55% by weight of solvent and from 10% to 30% by weight of silicone resin, and subjecting the thus coated web to a temperature of from 200 F. to 250 F. for from 30 seconds to 5 minutes to effect removal of the solvent.
  • a coating composition consisting essentially of from 1% to 3% by Weight of dimethyl-trimethylol melamine, from 5% to 10% by weight of a polyvinyl alcohol, from 5% to 10% by weight
  • the process of producing electrophotographic recording members which comprises, coating a web of paper with a coating composition consisting essentially of from 1% to 3% by weight of urea formaldehyde precondensate, from 2.5% to 7% by weight of a carboxylated copolymer of maleic anhydride and an ethylenically unsaturated monomeric material, from 5% to 10% by weight of polyvinyl acetate and the rest being substantially entirely water, subjecting the thus coated paper web to a temperature of from 250 F. to 360 F.
  • a coating composition consisting essentially of from 1% to 3% by weight of urea formaldehyde precondensate, from 2.5% to 7% by weight of a carboxylated copolymer of maleic anhydride and an ethylenically unsaturated monomeric material, from 5% to 10% by weight of polyvinyl acetate and the rest being substantially entirely water, subjecting the thus coated paper web to a temperature of from 250 F. to 360 F.
  • a coating composition consisting essentially of from 35% to 50% by weight of photoconductive zinc oxide particles, from 35% to 55% by weight of solvent and from 10% to 30% by weight of silicone resin, and subjecting the thus coated web to a temperature of from 200 F. to 250 F. for from 30 seconds to 5 minutes to effect removal of the solvent.
  • a process of producing electrophotographic recording members which comprises coating a paper web with a coating composition consisting essentially of from 1% to 35 by weight of dimethyl-trimethylol melamine, from 2.5% to 7% by weight of a copolymer of crotonic acid and vinyl acetate, from 5% to 10% by weight of polyvinyl acetate and the rest being substantially entirely water, subjecting the thus coated Web to a temperature 13 of from 250 F. to 360 F.
  • a coating composition consisting essentially of from 35% to 50% by Weight of photo-conductive zinc oxide particles, from 35 to 55% by weight of toluene and from 10% to 30% by Weight of silicone resin, and subjecting the thus coated web to a temperature of from 200 F. to 250 F. for from 30 seconds to 5 minutes to effect removal of the toluene.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
US241008A 1962-11-29 1962-11-29 Electrophotographic recording members and processes of preparing same Expired - Lifetime US3241958A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
BE639812D BE639812A (de) 1962-11-29
NL300364D NL300364A (de) 1962-11-29
US241008A US3241958A (en) 1962-11-29 1962-11-29 Electrophotographic recording members and processes of preparing same
DEP1272A DE1272123B (de) 1962-11-29 1963-11-05 Verfahren zum Herstellen elektrophotographischer Aufzeichnungsmaterialien
GB43884/63A GB1059137A (en) 1962-11-29 1963-11-06 Electrophotographic recording members and processes of preparing same
NL63300364A NL139211B (nl) 1962-11-29 1963-11-11 Elektrofotografisch materiaal.
FR955588A FR1388789A (fr) 1962-11-29 1963-11-29 Procédé de fabrication de pièces pour enregistrement électrophotographique et produits conformes à ceux obtenus par le présent procédé ou procédé similaire

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US241008A US3241958A (en) 1962-11-29 1962-11-29 Electrophotographic recording members and processes of preparing same

Publications (1)

Publication Number Publication Date
US3241958A true US3241958A (en) 1966-03-22

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US241008A Expired - Lifetime US3241958A (en) 1962-11-29 1962-11-29 Electrophotographic recording members and processes of preparing same

Country Status (5)

Country Link
US (1) US3241958A (de)
BE (1) BE639812A (de)
DE (1) DE1272123B (de)
GB (1) GB1059137A (de)
NL (2) NL139211B (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3468660A (en) * 1963-02-15 1969-09-23 Azoplate Corp Electrophotographic material comprising a multilayer support having a barrier layer over a duplex paper base
US3489559A (en) * 1965-05-28 1970-01-13 Mead Corp Components for electrophotographic compositions and processes
US3652271A (en) * 1967-09-01 1972-03-28 Addressograph Multigraph Photoelectrostatic recording member
US4133684A (en) * 1976-03-22 1979-01-09 Konishiroku Photo Industry Co., Ltd. Electrophotographic material with intermediate layer
US4252883A (en) * 1972-04-28 1981-02-24 Canon Kabushiki Kaisha Process for producing electrophotographic photosensitive member

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3468660A (en) * 1963-02-15 1969-09-23 Azoplate Corp Electrophotographic material comprising a multilayer support having a barrier layer over a duplex paper base
US3489559A (en) * 1965-05-28 1970-01-13 Mead Corp Components for electrophotographic compositions and processes
US3652271A (en) * 1967-09-01 1972-03-28 Addressograph Multigraph Photoelectrostatic recording member
US4252883A (en) * 1972-04-28 1981-02-24 Canon Kabushiki Kaisha Process for producing electrophotographic photosensitive member
US4133684A (en) * 1976-03-22 1979-01-09 Konishiroku Photo Industry Co., Ltd. Electrophotographic material with intermediate layer

Also Published As

Publication number Publication date
DE1272123B (de) 1968-07-04
BE639812A (de)
NL300364A (de)
GB1059137A (en) 1967-02-15
NL139211B (nl) 1973-06-15

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