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
  • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
  • G03G5/05—Organic bonding materials; Methods for coating a substrate with a photoconductive layer; Inert supplements for use in photoconductive layers
  • G03G5/0528—Macromolecular bonding materials
  • G03G5/0557—Macromolecular bonding materials obtained otherwise than by reactions only involving carbon-to-carbon unsatured bonds
  • G03G5/056—Polyesters
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
  • C09D167/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S525/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S525/931—Blend of stated incompatibility

Definitions

• ABSTRACT OF THE DISCLOSURE A recording element for electrostatic-printing wherein the photoconductive coating contains zinc oxide dispersed in a film of two partially incompatible resins.
• This invention relates to electrostatic printing and particularly to improved recording elements for electrostatic printing and methods of producing these recording elements.
• An electrostatic printing process is a process for producing a visible image or copy by converting a light image or signal into an electrostatic charge pattern on an electrically insulating base. The charge pattern is then converted or developed into a visible image by the application thereto of electrically-attractable particles.
• a typical electrostatic printing proces utilizing a photoconducting insulating stratum includes first producing a blanket electrostatic charge on the surface of the photoconducting stratum. The electrostatic charge may be stored on the surface for a time in the dark. The rate at which this stored electric charge is dissipated when the stratum is maintained in darkness is referred to as the dark decay of the stratum.
• a light image is focused on the charged surface, discharging the portions of the surface irradiated with light, leaving the remainder of the surface in a charged condition, and thereby forming an electrostatic image thereon.
• the electrostatic image is rendered visible by applying to the electrostatic image a developer substance, such as a pigmented thermolastic resin powder, which is held electrostatically to the charged areas of the surface.
• the visible image thus formed may be fixed directly to the surface, for example, by fusing the image thereto.
• thermoplastic resin powder A proces of electrostatic printing in which the thermoplastic resin powder is fused directly to the surface of the stratum is described in US. Patents 3,052,539 and 3,052,540, both to H. G. Greig.
• the recording elements of this invention may be most effectively used in the process and .apparatus described in the Greig patents and represent improvements of the recording elements described in the Greig patents.
• the recording element used in the process of the Greig patents comprises a backing sheet, such as paper coated with photoconductive white zinc oxide particles of high purity suspended in an electrically-insulating film-forming binder.
• the photoconductive zinc oxide preferably has a surface photoconductivity higher than ohms square/watt/cm. when exposed to a Wavelength of about 3900 A. and is very pure, e.g., zinc oxide C.P. or U.S.P.
• the electrically insulating film may be of a wide variety of substances. Synthetic resinous materials having high dielectric strengths are most desirable. These are known in the art as dielectric resins.
• Examples are polyvinyl acetate, copolymers of vinyl chloride-vinyl acetate, polystyrene, styrene-butadiene copolymer resins, and silicone resins.
• Other resin-like materials such as cellulose ethers and esters as well as natural resins may also be used.
• coating of the recording element may further include one or more organic dyes which are capable of absorbing radiant energy in bands of wave lengths to which said zinc oxide particles are relatively insensitive and transferring said absorbed energy to said zinc oxide particles, thereby substantially increasing the total sensitivity of the photoconductive coating to light.
• a photoconductive surface of increased light sensitivity will display an increased rate of discharge in the irradiated areas. This may also be termed an increased light decay rate.
• the resins which are blended together may beaosen from the wide variety of resins conventionally used as the sole binder resins in electrostatic recording elements. Such resins are generally described in US. Patents 3,052,539 and 3,052,340.
• the resins known as dielectric resins have high dielectric strengths. Among these resins are included acrylic ester polymers, rubber resins, polyester resins, polyvinyl acetate, copolymers of vinyl chloride-vinyl acetate, polystyrene, silicone resins, cellulose ethers, cellulose esters and shellac.
• Other suitable resins as Well as some particularly desirable blends for the practice of this invention will be discussed in greater detail hereinafter.
• the percent haze is also calculated for the uncoated glass slide and the resulting percent haze is substracted from the percent haze .of the coated slide to give the actual percent haze of the film.
• the percent haze given will be the corrected or actual percent haze of the film.
• similar coated slides are prepared in which each of the two resins of the blend is used alone in an amount equal to total weight of the blend and percent haze is determined in each case.
• the film of partially incompatible blend will show a higher haze percentage than films in which the component resins are used alone.
• the film of the blend should appear to be continuous to the naked eye. There should be an absence of macroscopic discontinuities in the film.
• the haze on the slide containing the blend will be visible to the naked eye, giving the coating a milky white or frosted appearance.
• the haze percentage of dry films of the blend are preferably greater than 1% and less than 48%. At haze percentages over 48%, macroscopic discontinuities begin to appear in many cases.
• the photoconductor is preferably zinc oxide of the type described in U.S. Patent 3,052,539
• other finely divided conventional photoconductors may be used such as the oxides of antimony, aluminum, bismuth, cadmium, mercury, molybdenum and lead; the iodides, selenides, sulfides or tellurides of these metals including zinc; selenium; arsenic trisulfide; lead chromate and cadmium arsenide.
• the coating may also contain other conventional additives such as the waxes e.g., parafiin and carnauba and the plasticizers described in U.S. Patent 3,052,539 as well as sensitizing dyes such as those described in U.S. Patent 3,052,539.
• waxes e.g., parafiin and carnauba
• plasticizers described in U.S. Patent 3,052,539
• sensitizing dyes such as those described in U.S. Patent 3,052,539.
• the resins is a polyester resin comprising the condensation polymerization product of ethylene glycol and terephthalc acid.
• Excellent results may be effected by blending, as a first component, polyester resins which are polymers of ethylene terephthalate containing ethylene sebacate or ethylene adipate, preferably in minor amounts. (These polymers are produced by the condensation polymerization of ethylene glycol, terephthalic acid and sebacic or adipic acid), with, as a second component, polyester resins described in U.S. Patent 2,965,613 to Milone et al.
• polyester resins of this type are commercially available under the Vitel trademark, polyester resin Vitel PE207 being equivalent to the first component in the blend and polyester resins Vitel PE100 and Vitel PE200 being equivalent to the second component in the blend.
• polyester resins also give very good results when blended with other resins so as to be partially incompatible.
• blends of the polyester resins of Patent No. 2,965,613 having the higher ethylene isophthalate-content polyester resins as a second component with acrylic ester polymers as the first component have been found to be very good embodiments of this invention.
• acrylic ester polymers are preferably homopolymers and copolymers of esters of acrylic or methacrylic acids with lower alkyl alcohols.
• blends of the higher ethylene terephthalate-content polyester resins or the ethylene terephthalate-ethylene sebacate or adipate as a first component and styrene-butadiene rubber resins as a second component have been quite effective as have blends of acrylic ester copolymers and styrenebutadiene rubber resins.
• Example 1 The following mixture is ball milled to a smooth consistency:
• Lucite 2046 (a copolymer of n-butylmethacrylate and 50% isobutyl methacrylate) 7.3 Pliolite S-7 (a rubber resin consisting of a copolytrier of styrene and 30% butadiene) 1.8 Zinc oxide (Photox 801) 45.1 Toluene 41.0 Rose Bengal dye (a 0.12% solution in methanol) 6.0 Methylene Blue dye (a 0.12% solution in methanol) 2.0 Iosol Yellow dye (a 0.24% solution in toluene) 4.0
• the mixture is then coated on white bond paper using a doctor roller and the coated paper is air dried to a dry film thickness of 0.5 mil.
• each of the three sheets is negatively charged and exposed to a light image and then developed to form a copy.
• the sheet containing the blend of the two resins gives copies having images of equivalent intensity to those formed on the sheet containing Pliolite S7 alone but in almost onefourth the exposure time.
• the sheet containing the blend gives images of equivalent intensity to those containing Lucite 2046 alone in less than one-half the exposure time.
• compositions of the above resins in which the dyes and the zinc oxide have been eliminated are prepared. They have the following compositions:
• Percent of the total light scattered Percent of the total light transmitted the percent haze is determined in case to be:
• Example 2 Following the procedure of Example 1, a coated copying paper is prepared from the following composition:
• the sheet containing a coating of the blend gives copies having images of equivalent intensity to those formed on the sheets containing coating of either resin alone in about /a the exposure time.
• films on glass slides are prepared of the blend and of the component resins individually by eliminating the zinc oxide and the dyes from the compositions of this example.
• Example 3 Following the procedure of Example 1, a coated copying paper is prepared from the following composition:
• the haze in the blend film is also markedly visible to the naked eye.
• Example 4 Following the procedure of Example 1, a coated copying paper is prepared from the following composition:
• sheets are prepared with copolyester and polymethylmeth-acrylate alone in place of the resin blend.
• the sheets coated with compositions containing the blend give copies having images of equivalent intensity to those formed on the sheets containing coatings of either resin alone in about /2 the exposure time.
• the haze in the film of the blend is also markedly visible to the naked eye.
• Example 5 Fol-lowing the procedure of Example 1, a coated copying paper is prepared from the following composition:
• the haze .in the film of the blend is also markedly visible to the naked eye.
• a recording element for electrostatic printing comprising a base sheet carrying a photoconductive insulating layer comprising zinc oxide suspended in an electrically insulating film-forming vehicle which comprises a blend of two partially incompatible resins in such proportions that said resins are partially incompatible with each other to the extent that a dry film of the blend alone deposited from an organic solution has a greater haze than films of equivalent thickness containing either of the resins alone in an amount equal to the total resin content of the blend while having an absence of macroscopic discontinuities, said blend of resin being of the group (A) a blend of polyesters, wherein one of the resins is a polyester comprising the condensation polymerization product of ethylene glycol and an acid component comprising at least 25% of the total acid compound weight of isophthalic acid and the remainder terephthalic acid, and the other resin is a polyester comprising the condensation polymerization product of ethylene glycol and an acid component comprising terephthalic acid and sebacic acid, (B) a blend wherein one of the resins is a
• one of the resins is a copolyester comprising ethylene terephthalate and ethylene isophthalate, at least one part of ethylene isophthalate being present in the copolyester for each 3 parts of ethylene terephthalate, and the other resin is poly n-butylmethacrylate) 5.
• one of the resins is a copolyester of ethylene terephthalate and ethylene sebacate and the other resin is a copolymer of styrene and butadiene.
• one of the resins is a copolymer of n-butylmethacrylate and isobutylmethacryl-ate and the other resin is a copolymer of styrene and butadiene.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Polymers & Plastics (AREA)
• Medicinal Chemistry (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Photoreceptors In Electrophotography (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Priority Applications (8)

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Cited By (9)

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Citations (8)

• 1964
  • 1964-02-06 US US343152A patent/US3378370A/en not_active Expired - Lifetime
• 1965
  • 1965-01-26 GB GB3327/65A patent/GB1077053A/en not_active Expired
  • 1965-01-29 BE BE659027D patent/BE659027A/xx not_active IP Right Cessation
  • 1965-02-05 CH CH157965A patent/CH438946A/fr unknown
  • 1965-02-05 ES ES0309018A patent/ES309018A1/es not_active Expired
  • 1965-02-05 DE DE19651497157 patent/DE1497157A1/de active Pending
  • 1965-02-08 NL NL6501531A patent/NL6501531A/xx unknown

Patent Citations (8)

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