US3586532A - Electrostatic copy sheet of increased speed - Google Patents

Electrostatic copy sheet of increased speed Download PDF

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Publication number
US3586532A
US3586532A US719744A US3586532DA US3586532A US 3586532 A US3586532 A US 3586532A US 719744 A US719744 A US 719744A US 3586532D A US3586532D A US 3586532DA US 3586532 A US3586532 A US 3586532A
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US
United States
Prior art keywords
glycol
zinc oxide
photoconductive
speed
electrostatic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US719744A
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English (en)
Inventor
Robert Freed
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AB Dick Co
Original Assignee
AB Dick Co
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Filing date
Publication date
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Publication of US3586532A publication Critical patent/US3586532A/en
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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
    • G03G5/0503—Inert supplements
    • G03G5/051—Organic non-macromolecular compounds
    • G03G5/0514—Organic non-macromolecular compounds not comprising cyclic groups
    • 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
    • G03G5/09—Sensitisors or activators, e.g. dyestuffs

Definitions

  • This invention relates to electrophotography copy systems and to copy sheets having photoconductive coatings for use in electrostatic image development and it relates more particularly to the improvement in photoconductive compositions which are sensitive to visible light for use in the production of copy.
  • An electrostatic printing process is one capable of producing a visible image by electrostatic technique.
  • a process of the type described is referred to in the art as the Xerox process, which makes use of a selenium drum, or Electrofax process, which makes us of a photoconductive coated paper and includes the steps of converting a light image or electrical signal into an electrostatic charge pattern on the photoconductive electrically insulating layer. The pattern is developed into a visible image with the resultant production of visible copy.
  • a typical electrostatic process conventionally includes the preparation of an electrophotographic recording element, for example by coating the surface of a base sheet such as paper with a photoconductive insulating material, such as zinc oxide dispersed in an electrically insulating film forming vehicle, such as a silicone resin.
  • the recording element is subjected to corona discharge at high voltage to produce an electrostatic charge on the photoconductive surface.
  • corona discharge at high voltage to produce an electrostatic charge on the photoconductive surface.
  • the portions irradiated by the light rays are discharged to leave the remainder of the surface in a charged condition to define a latent electrostatic image.
  • This image is rendered visible in a conventional manner, such as by applying a developing powder or a developer liquid whereby the pigment adheres electrostatically to the charged areas of the sheet and the image is subsequently fixed directly to the photoconductive coating as by heat, adhesive, vapor or the like.
  • a developing powder or a developer liquid whereby the pigment adheres electrostatically to the charged areas of the sheet and the image is subsequently fixed directly to the photoconductive coating as by heat, adhesive, vapor or the like.
  • a detailed description of a typical electrostatic printing process is set forth in the Greig Pat. No. 2,874,063, issued on Feb. 17, 1959. The patent describes a process in which a sheet of paper having a coating containing relatively pure zinc oxide is charged by corona discharge to a potential of approximately 600 to 800 volts.
  • a latent image is formed by photographic exposure and the image is developed by contacting the paper with a developer composition such as iron particles mixed with a powder of carbon pigmented resin.
  • An electrostatic recording element of the type described is ordinarily prepared by first mixing a finely divided photoconductor and the electrically insulating film forming vehicle with a volatile solvent such as by mixing zinc oxide and the silicone resin with toluene. The mixture is coated onto the base sheet and dried and the coated sheet is then cut to size.
  • the light sensitivity of the charged zinc oxide layer is normally at its greatest in the ultraviolet region of the spectrum, whereas the source of exposure may have its maximum output in a region of the spectrum which lies within the visible range, such as an ordinary tungsten lamp.
  • the term speed is used to define light sensitivity of the electrophotographic coating and it is measured by the amount of light in foot candle seconds required to decay the charge to a stable residual potential. Thus the lower the numerical value, the faster the light sensitivity or speed of the coating.
  • the term dark decay, measured in volts/ second, relates to the loss of charge of the electrophotographic coating in the dark. Another property used to measure electrophotographic coatings is charge acceptance which is measured in volts.
  • Electrophotographic coatings employed in present practice are formulated, as described, of photoconductive material, such as zinc oxide, of the type marketed by the New Jersey Zinc Company under the trade name Photox Zinc Oxide, or of the type marketed "by the American Zinc Company under the trade name Azo ZZZ-661 Zinc Oxide, and an insulating resinous binder such as styreneethyl acrylate, silicone resins (Silicone SR-82), modified urethane oil, modified urethaneoil-silicone resin, polyvinyl acetate, polyvinyl acetate-alkyd resin mixtures, modified polyvinyl acrylate, or other film forming insulating resin and photoconductive pigment as described in US. Patents Nos. 3,052,539; 3,121,006; 3,121,- 007; 3,132,941, and the aforementioned Greig Patent No. 2,874,063.
  • photoconductive material such as zinc oxide, of the type marketed by the New Jersey Zinc Company
  • Dyestuffs capable of use for increasing the light sensitivity of the described electrophotographic coatings include: Brom Phenol Blue, Dibromofluorescein, Erythrosine B, Rose Bengal, Sulpho Rhodamine, Rhodamine B Extra, Eosin OJ concentrate, Auromine O concentrate, Quinaline Yellow, Brom Cresol Purple, Phloxine B, Acradine Orange, Fushin, Methylene Blue, Kiton Blue, Tartrazine concentrate, or others of the dyestuffs described in the aforementioned list of patents.
  • the sensitivity and speed of electrophotographic coatings on conductive base sheets can be increased by formulation of the photoconductive coating to include a glycol as a component thereof. It has been found that such glycol is especially effective to increase the speed of electrophotographic coatings of photoconductive zinc oxide in a suitable insulating resinous binder which also embodies a sensitizing dye or dyes and that such increase in speed can be effected without increase in the concentration of sensitizing dyestuffs. In fact, a synergistic effect is indicated in that the combination of dye sensitization and glycol provide speeds incapable of being reached by use of the dystuff alone, even at higher concentrations, and that the increase in speed can be achieved even with a decrease in dye concentration. It has been found that the increase in speed is maximized when a monohydroxy alcohol is employed as the diluent for the dye blend in the coating composition formulated of the glycol, photoconductive zinc oxide, insulating resinous binder and sensitizing dyestuff.
  • glycol use can be made of mono-, diand triethylene, propylene, butylene and up to hexylene glycols with best results being secured with propylene glycol and triethylene glycol.
  • the amount of glycol when calculated on the basis of a 1% solution of dyestuff or dye blend, may range from 0.05 ml. to 2.0 ml. of glycol per 3.5 ml. of the solution of dyestuff or, when calculated on the solids basis, the glycol may range from 0.05 to 2.0 ml. of glycol per 0.035 gram of dyestuff in the electrophotographic coating composition, with the preferred range being 0.4 to 0.8 ml. of glycol per 0.01 gram of dyestuif.
  • EXAMPLE 1 206 grams styrene-acrylate copolymer resin, solids (DeSoto Resin 15104-028) 134 grams polyethylene-orthophthalate polystyrene blend,
  • the dye blend is a mixture of 0.4 gram of the sodium salt of Brom Phenol Blue, 0.4 gram of the sodium salt of fluorescein and 0.2 gram of Vietnameserysine GGA concentrate, all dissolved in ml. of methanol.
  • the dye blend is incorporated in an amount corresponding to 1 cc. of the solution per 100 grams of zinc oxide.
  • the glycol is incorporated in Example 1 in an amount to correspond to /2 cc. per 100 grams of zinc oxide.
  • compositions of Examples 1 to 3 are coated by conventional coating technique onto suitable base paper in coating weights of from 10-20 pounds per 3,000 square feet of surface area and then air dried or dried at elevated temperature at less than 350 F.
  • the speed or light decay of the electrophotographic coating produced by Example 1 measures 3.08 foot candle-seconds.
  • the electrophotographic sheet produced by Example 2 has a light decay (speed) of 3.81 foot candle-seconds.
  • Example 4 is the same as Example 1 but without the glycol.
  • Example 5 is the same as Example 1 but with the propylene glycol added in an amount to correspond to 0.05 ml. per 3.5 ml. of dye blend.
  • Example 6 is the same as Example 1 but with 2.0 ml. of propylene glycol per 3.5 ml. of the dye blend.
  • Example 7 is the same as Example 1 but with 0.05 ml. of triethylene glycol per 3.5 ml. of dye blend.
  • Example 8 is the same as Example 1 but with 2.0 ml. of triethylene glycol per 3.5 ml. of dye blend.
  • Electrofax paper having the zinc oxide, photoconductive, dye sensitized coating.
  • Examples 9 .to 15 show that an increase in speed is secured by the addition of propylene glycol with each alcohol dye blend but that the increase in speed was more favorable with the lower alcohols with best results being provided by methanol.
  • glycol as a sensitizer in the manner described oflers a number of advantages in that glycols can be added to the dye blend or coating mix withoutin any way disturbing the stability of the coating or the coatability of the composition in fabrication of the electrophotographic element. This effectiveness of the glycols .to increase the speed of the paper is achieved without impairing dark decay, charge acceptance, light sensitivity or color of the electrophotographic coating.
  • An electrostatic copy sheet formed of a base sheet and a photoconductive coating on the surface of the base sheet formed of a composition containing an alkylene glycol containing 1-6 carbon atoms in combination with particles of a photoconductive material and insulating resinous binder.
  • An electrostatic copy sheet as claimed in claim 2 which contains in addition a sensitizing dyestufi or dyestuffs.
  • An electrostatic copy sheet as claimed in claim 3 in which the sensitizing dyestutf is introduced in solution with a monohydroxy alcohol.
  • An electrostatic copy sheet is claimed in claim 4 in which the alcohol is a lower alcohol.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Photoreceptors In Electrophotography (AREA)
US719744A 1968-04-08 1968-04-08 Electrostatic copy sheet of increased speed Expired - Lifetime US3586532A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US71974468A 1968-04-08 1968-04-08

Publications (1)

Publication Number Publication Date
US3586532A true US3586532A (en) 1971-06-22

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US719744A Expired - Lifetime US3586532A (en) 1968-04-08 1968-04-08 Electrostatic copy sheet of increased speed

Country Status (8)

Country Link
US (1) US3586532A (enrdf_load_stackoverflow)
JP (1) JPS4825661B1 (enrdf_load_stackoverflow)
BE (1) BE731203A (enrdf_load_stackoverflow)
CH (1) CH518576A (enrdf_load_stackoverflow)
DE (1) DE1917820A1 (enrdf_load_stackoverflow)
FR (1) FR2005736A1 (enrdf_load_stackoverflow)
GB (1) GB1251869A (enrdf_load_stackoverflow)
NL (1) NL6905063A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3847661A (en) * 1971-12-20 1974-11-12 Wiggins Teape Res Dev Electrostatic imaging paper
US7038290B1 (en) * 1965-09-28 2006-05-02 Li Chou H Integrated circuit device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7038290B1 (en) * 1965-09-28 2006-05-02 Li Chou H Integrated circuit device
US3847661A (en) * 1971-12-20 1974-11-12 Wiggins Teape Res Dev Electrostatic imaging paper

Also Published As

Publication number Publication date
NL6905063A (enrdf_load_stackoverflow) 1969-10-10
FR2005736A1 (enrdf_load_stackoverflow) 1969-12-19
BE731203A (enrdf_load_stackoverflow) 1969-09-15
JPS4825661B1 (enrdf_load_stackoverflow) 1973-07-31
GB1251869A (enrdf_load_stackoverflow) 1971-11-03
DE1917820A1 (de) 1969-12-18
CH518576A (de) 1972-01-31

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