Classifications

• • 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
  • G03G5/02—Charge-receiving layers
  • G03G5/0202—Dielectric layers for electrography
  • G03G5/0205—Macromolecular components
• • 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
  • G03G5/02—Charge-receiving layers
  • G03G5/0202—Dielectric layers for electrography
• • 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
  • G03G5/02—Charge-receiving layers
  • G03G5/0202—Dielectric layers for electrography
  • G03G5/0217—Inorganic components
• • 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
  • G03G5/10—Bases for charge-receiving or other layers
  • G03G5/101—Paper bases
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
  • Y10T428/258—Alkali metal or alkaline earth metal or compound thereof
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/31935—Ester, halide or nitrile of addition polymer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31971—Of carbohydrate
  • Y10T428/31993—Of paper

Definitions

• Electrostatic recording paper is made by applying three successive aqueous coats to the machine glazed side of a paper web.
• the first coat contains titanium dioxide and an electroconductive water dispersible polymer of a vinylbenzyl quaternary ammonium compound.
• the second coat is oxidized starch and calcium carbonate.
• the third coat contains calcium carbonate and a carboxylated polyvinyl acetate in ammoniacal solution. The web is dried between successive coatings and may be finally steam treated.
• This invention relates to a composite paper product suitable for electrostatic printing, and a method of making such product. More particularly, this invention relates to a coated electrographic paper wherein all coatings comprise an aqueous medium and are applied by conventional coating equipment.
• Electrographic printing broadly comprises the formation of a latent electrostatic image on a suitable sheet of material, followed by development of the image by application of a toner.
• a paper web having a dielectric or insulating surface while being carried upon a grounded support, is passed into close proximity with styli that may be electrically energized as desired.
• Energizing of selective styli results in a corresponding group of charged spots on the surface of the paper, whereby the desired image is formed.
• the charged spots are then treated or developed with an oppositely charged, colored resinous powder dispersed in a volatile solvent, which selectively clings to the charged areas. Heat or pressure is then applied to the paper, thereby fusing the resinous powder to the paper and forming a permanent print.
• electrographic recording paper has been made by applying a dielectric coating on a relatively conductive sheet.
• Various compounds, such as salts and other compounds capable of retaining or attracting conductive moisture in the sheet may be incorporated into the paper to enhance conductive properties.
• the conductive layer is applied on one side of the sheet and the dielectric is applied to the other side. In other cases, the dielectric is applied over the conductive layer.
• electrographic paper Some types have previously been made by applying a dielectric film of plastic material, such as polyethylene or polystyrene to the paper surface, either by extrusion or by deposition from a volatile organic solvent, such as toluene. These methods have been found to be impractical because of high expense, and because of the difliculties, including fire hazards and toxicity, of using a volatile solvent in a coating operation.
• a dielectric film of plastic material such as polyethylene or polystyrene
• An object of this invention is to provide multiple coat electrostatic printing paper and method for its production wherein the dielectric coat remains distinct from, and does not interact with, the base coat.
• Another object of this invention is the provision of an electrographic paper of low gloss and having smooth surface which is receptive to writing instruments.
• a further object of this invention is to provide an improved method for producing electrographic paper wherein all coatings are applied in an aqueous medium and the resulting product has excellent solvent holdout characteristics and good handling properties.
• the process of the present invention is preferably carried out on a conventional coating apparatus having means for applying an aqueous mixture of solids onto a web moving at high speeds, as well as means for drying, steaming and winding the coated paper.
• a paper web having a machine finish is suitable for the purposes of the invention, a machine glazed paper, such as that produced on a Yankee machine, is preferred.
• the first step of the process comprises applying a conductive base coat to the paper by applying an aqueous mixture of finely divided titanium dioxide and a water soluble conductive compound, such as a vinylbenzyl quaternary ammonium compound, preferably polymerized vinylbenzyl trimethyl ammonium chloride (Dow -ECR-34).
• a vinylbenzyl quaternary ammonium compound preferably polymerized vinylbenzyl trimethyl ammonium chloride (Dow -ECR-34).
• the relative proportions of the vinylbenzyl compound and the titanium dioxide are not critical, and a 24 percent solids mixture in water containing from about 30% to about 70% by weight of the vinylbenzyl compound with the remainder as titanium dioxide has been found to give acceptable results.
• the mixture is applied in a conventional manner by means of a blade coater in weights ranging from about one to about two pounds per ream (3300 sq. ft.) to the glazed or polished surface of the unsized web in order to produce a smooth and even coating
• the titanium dioxide in the base coat is beneficial in imparting brightness to the paper and has been found to be fully compatible with the vinylbenzyl trimethyl ammonium chloride, in that conductivity of the deposited mixture is approximately the same as that of the vinylbenzyl compound alone.
• the vinylbenzyl compound serves primarily as a conductive medium, although it is believed that this compound also acts as a humectant and may form a partial barrier to solvents.
• a second coating is then applied over the dried base coat, the purpose of which is to form a relatively impenetrable but fully compatible layer between the conductive base and the dielectric top coating.
• the layer is preferably applied by a blade coater and consists essentially of an aqueous 40 to 45 percent solids mixture of oxidized or enzyme converted starch, such as a brand known as Clinton-X, and calcium carbonate, preferably Snowflake, calcium carbonate (Thompson, Weinman and Company) or its equivalent having particle sizes within the range of about one to about 24 microns.
• the relative proportions of calcium carbonate and starch are not critical and are largely determined by the nature of the coating equipment employed. At relatively high calcium carbonate levels (above 80% by weight), problems such as inadequate solvent holdout and excessive blade wear on blade coaters may occur. At relatively low calcium carbonate levels (below 20% by weight) problems may be encountered in applying the coating to the web by conventional methods.
• the preferred relative proportion of calcium carbonate in the coating mixture is within the approximate range of from about 30% to about 70%, with the remainder as starch.
• the coating weight is preferably maintained within the range of about from two to four pounds per ream, with three pounds being optimum.
• the calcium carbonate has been subjected to little or no surface treatment during processing, which would render this pigment conductive.
• the use of calcium carbonate, as compared to clay or other commercial coating agents such as titanium dioxide, has been found to be uniquely suitable for purposes of the present invention.
• the calcium carbonate not only serves as a bulk carrier for the solubilized starch and provides continuity to the coating, but also is entirely compatible with the other coats and aids in reducing overall gloss, without affecting Charge Acceptance of the product.
• the starch provides the necessary barrier between the conductive and dielectric coatings and aids in preventing penetration of toner solvents into the web.
• a dielectric coating composition consisting essentially f an aq cus mixture of calcium. arbonate and a water soluble dielectric.
• a suitable dielectric is carboxylated polyvinyl acetate such as that sold as Monsanto CSVlO, dissolved in an aqueous ammoniacal solution
• the aqueous mixture contains 27 to 30 percent solids in proportions of about from 50% to about by weight of polyvinyl acetate with the remainder as Snowflake calcium carbonate.
• the particle size of the calcium carbonate is very important and should range in the order of about one to about 24 microns, with a mean particle size of about 5 microns.
• Sufficient ammonium hydroxide is added to dissolve the polyvinyl acetate or until a pH of about 8.0 to 9.5 has been attained.
• the coat weight is preferably maintained in the order of from two to three pounds per ream.
• a base conductive coat may also be applied to the back or unglazed side of the web either by means of a blade or air knife coater.
• the coat applied is preferably identical in nature and proportions to the base coat previously described and consists essentially of an aqueous mixture of titanium dioxide and polymerized vinylbenzyl trimethyl ammonium chloride. Coating on the back side in this manner has been found to enhance electrostatic printing qualities as well as to minimize possible curl tendencies in the web.
• a second application of the dielectric coating composition may be made on the side previously coated with dielectric for the purpose of assuring uniformity.
• about one to one and one-half pounds of solids per ream are applied, such that a total of about four to four and one-half pounds of dielectric coating is applied to the web.
• the web is then passed through a final drier and may be wound into a roll.
• the moisture level in the web may be increased to about 6 or 7 percent in order to decrease curl tendencies of and cockle in the web, as well as to improve conductivity of the base coat and hence imaging of the product.
• Moisture is preferably imparted to the web at this stage by passing only the back side of the web through a steam shower.
• the back side of the web was coated by an air knife with the same base coat as that applied to the glazed surface of the web.
• the web was then dried, and a dielectric coat was applied by a blade coater over the second coat on the glazed side.
• the dielectric coat was a 30% solids, aqueous, ammoniacal mixture containing two and one-half parts of a carboxylated polyvinyl acetate (Monsanto C5V10) to one part Snowflake calcium carbonate and was applied at a rate of about 3 pounds per ream.
• the web was then dried, and a second coating of about one pound of the dielectric was applied with a blade coater.
• a method of making an electrostatic recording paper comprising the steps of applying a first coat to one side of a web of paper, said first coat consisting essentially of an aqueous mixture of titanium dioxide and a vinylbenzyl quaternary ammonium compound, drying the web, then applying a second aqueous coat over said first coat, said second coat consisting essentially of starch and calcium carbonate, then drying said web, and then applying over said second coat a third coat consisting essentially of an aqueous mixture of calcium carbonate and carboxylated polyvinyl acetate.
• the first coat consists essentially of a 28 percent solids mixture of titanium dioxide and polyvinyl benzyl trimethyl ammonium chloride
• said second coat contains a 40 to 45 percent solids mixture of oxidized or enzyme converted starch and calcium carbonate
• said third coat contains 27 to 30 percent solids mixture of carboxylated polyvinyl, acetate dissolved in ammoniacal solution and calcium carbonate, the calcium carbonate in said second and third coat having a particle size of from about one to 24 microns.
• solids of said second coat comprise from about 30% to about 70% calcium carbonate, with the remainder as starch.
• a method for treating a web of paper to produce electrostatic recording paper comprising the steps of ap plying a first coat of about from one to two pounds per ream to one surface of the web containing an aqueous mixture of a water soluble conductive material and titanium dioxide, applying a second coat over said first coat of about from two to four pounds per ream of an aqueous mixture of starch and calcium carbonate having a particle size of about from one to 24 microns, applying a coat of about from one to two pounds per ream of an aqueous mixture of a conductive material and titanium dioxide to the other surface of the web, applying a third coat over said second coat of about from two to 4 and one-half pounds per ream of an aqueous mixture of a water soluble dielectric material and calcium carbonate having a particle size of from about one to 24 microns.
• the water soluble conductive material is polyvinyl benzyl trimethyl ammonium chloride
• the dielectric material is car- -boxylated polyvinyl acetate in ammoniacal solution.
• An electrostatic recording paper comprising a paper base having opposed surfaces, at first coating on a first surface of said base containing titanium dioxide and a conductive material, a second barrier coat over said first coat containing starch and calcium carbonate having a particle size of about from one to 24 microns, and a third coat over said second coat containing a dielectric material and calcium carbonate having a particle size of about from one to 24 microns.
• the conductive material is polyvinyl benzyl trimethyl ammonium chloride
• the dielectric material is the deposited residue of a polyvinyl acetate polymer.
• an electrostatic recording paper having a base sheet with a conductive coating containing titanium dioxide and an outer dielectric layer containing calcium carbonate, the improvement comprising a barrier layer between the base sheet and the: dielectric layer, said barrier layer being compatible. with said conductive coating and dielectric layer and consisting essentially of starch and calcium carbonate having a particle size up to about 24 microns.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Paper (AREA)
• Electrophotography Using Other Than Carlson'S Method (AREA)
• Photoreceptors In Electrophotography (AREA)
• Fax Reproducing Arrangements (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22639838

Family Applications (1)

Country Status (2)

Cited By (21)

• 1971
  • 1971-08-26 US US00175323A patent/US3759744A/en not_active Expired - Lifetime
• 1972
  • 1972-05-20 JP JP47050309A patent/JPS4831945A/ja active Pending

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