Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G13/00—Electrographic processes using a charge pattern
  • G03G13/14—Transferring a pattern to a second base
  • G03G13/18—Transferring a pattern to a second base of a charge pattern
• • 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 or to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/02—Charge-receiving layers
• • 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
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
  • Y10T428/264—Up to 3 mils
  • Y10T428/265—1 mil or less

Definitions

• a receiving element which also has a low Sheffield Smoothness value.
• the smooth surfaced member is then placed in face-to-face contact with the receiving element in the presence of a thin layer of an electrically insulating isoparafiinic hydrocarbon transfer liquid having a boiling point in the range of 105 to 260 C. During contact, the charge pattern is transferred to the receiving element in the absence of external pressure or electrical bias potential. The transferred image is then developed to form a high resolution visible image.
• This invention relates to electrostatic imaging procedures and more particularly to procedures for transferring and developing electrostatic charge patterns.
• a sensitive element which is typically in the form of an electrophotographic element.
• Suitable elements comprise a conductive support having thereon a layer of a photoconductive composition generally comprising a resinous binder and a photoconductor which may be organic or inorganic and which will accept and retain an electrostatic charge when in darkness.
• a suitable electrostatic charge is placed on the sensitive element by, for example, subjecting the element to a corona discharge. After charging, such an element is given an imagewise exposure by any suitable means. The exposure results in a variation in the charge on the element in accordance with the relative energy received by the element during exposure. This charge pattern is usually referred to as an electrostatic charge pattern.
• the charge pattern can now be rendered visible by the application of a suitable developer containing electrostatically attractable marking particles which are drawn to the element in accordance with the charge pattern thereon.
• the visible pattern thus formed is typically transferred to a receiver sheet and permanently afiixed thereto.
• Transfer processes of this type have several disadvantages where it is desired to reuse the photoconductor. If the image is developed with dry materials, the developing and transferring steps can result in considerable abrasion to the photoconductive surface. Abrasion is undesirable as it causes a reduction in image quality. If the electrostatic charge pattern is developed using liquid developers, the surface of the photoconductor often becomes coated with an uneven scum of dried developer. Unwanted deposits of this type adversely affect the electrical properties of the sensitive element. Attempts to remove these deposits may result in abrasion damage or solvent attack of the surface of the element.
• a further disadvantage of the materials and process described in the above patent is that high resolutions are not attainable. In fact, when the invention is practiced according to the patent resolutions of only 30 to 60 lines per millimeter are obtained. Such low resolution capability makes such a process entirely unsuited where high resolution is required as, for example, in microimage recording and reproduction.
• the minimum resolution requirement for Class I (negative camera microimage) at 16X reduction ratio is 101 line pairs/mm. At a 30X reduction ration, the minimum requirement is line pairs/ mm.
• a further object of this invention is to provide a new method of transferring electrostatic charge patterns which is rapid and simple.
• Another object of this invention is to provide a novel process for transferring and developing electrostatic charge patterns to obtain images of high resolution.
• charge-image-bearing members and receiving elements having extremely smooth surufaces.
• a charge pattern is formed on an image-bearing member which is then wetted with certain electrically insulating liquids.
• a smooth surfaced receiving element is then placed in contact with the wetted member and the charge pattern is transferred to the element without the application of any pressure or external electrical connections.
• the transferred pattern is then developed to form a visible image.
• an electrostatic charge pattern is produced on an image-bearing member by any of the suitable techniques known in the art of electrography.
• One particularly useful means of producing such charge patterns is by electrophotographic techniques.
• Electrophotography involves the use of a sensitive element typically comprising a conducting support having coated thereon a layer of a photoconductive composition.
• Suitable supporting materials for use in elements of the type described above can include any of a wide variety of electrically conducting supports, for example, paper (at a relative humidity above 20 percent), aluminum foil-paper laminates; metal foils such as aluminum foil, zinc foil, etc.; metal plates, such as aluminum, copper, zinc, brass and galvanized plates; vapor deposited metal layers such as silver, nickel, aluminum and the like coated on paper or conventional photographic film bases such as cellulose acetate, polystyrene, poly(ethylene terephthalate), etc.
• electrically conducting supports for example, paper (at a relative humidity above 20 percent), aluminum foil-paper laminates; metal foils such as aluminum foil, zinc foil, etc.; metal plates, such as aluminum, copper, zinc, brass and galvanized plates; vapor deposited metal layers such as silver, nickel, aluminum and the like coated on paper or conventional photographic film bases such as cellulose acetate, polystyrene, poly(ethylene terephthalate), etc.
• Such conducting materials as nickel can be coated by vacuum deposition on transparent film supports in sufficiently thin layers to allow electrophotographic elements prepared therewith to be exposed from either side of such be-preparedbycoating a'su'pport material such" as poly (ethylene terephthalate) witlra conducting layer containing a semiconductor such as cuprous iodide dispersed in a resimSuch conducting layers both with and Without insulating barrier layers are described in U.S.Pats. 3,245,833 and 3,428,451.
• a suitable conducting coating can be prepared from the sodium salt of a carboxyeste'r lactone of maleic anhydride and a vinyl acetate polymer.
• the photoconductive compositions which'can be coated on the above supports include a wide variety of materials.
• Useful compositions typically comprise a photoconductive compound in an electrically insulating, filmforming resin binder.
• Both inorganic and organic photoconductors can be used in the present invention as well as mixtures of two or more photoconductors. Suitable inorganic photoconductors would include zinc oxide, cadmium sulfide, cadmium selenide, titanium dioxide and others;
• Useful organicphotoconductors include the following materials.
• Arylamine photoconductors including substituted and unsubstituted arylamines, diarylamines, nonpolymeric triarylamines and polymeric triarylamines such as those described in U.S. Pats. 3,240,597 and 3,180,730.
• Z represents a mononuclear or polynuclear. divalent aromatic radical, either fused or linear (e.g., phenyl, naphthyl, biphenyl, 'binaphthyl, etc.), or a substituted divalent aromatic radical of these types wherein said substituent can comprise a member such as an acyl group having from 1 to about 6 carbon atoms (e.g., acetyl,'propionyl, butyryl, etc.), an alkyl group having from -lto about 6 carbon atoms (e.g., methyl, ethyl, propyl, butyl, etc.), an alkoxy group having from 1 to about 6 carbon atoms (e.g., methoxy, ethoxy, propoxy, pentoxy, etc.) or a nitro group; Z represents a mononuclear or polynuclear monovalent or polynuclear monovalent aromatic-radical, either fused or linear (e.
• acyl group having from 1 to about 6 .carbon atoms (e.g.,
• acetyl, propionyl, butyryl, etc. an alkyl group-having from 1 to about 6 carbon atoms (e.g., methyhethyl, propyl, butyl, etc.), an alkoxy group having from 1,to about 6 carbon atoms (e.g., methoxy, propoxy, Collaborationoxy,
• Q can represent ahydrogen atom or an aromatic amino group, such as Z'NH ;
• ,b represents ,an integer from 1 to about 12, and Lreplesents a hydrogen atom, a mononuclear or polynuclear, aromatic radical, either fused or linear (e.g.,.phenyl, naphthyl, bi-
• phenyl, etc. a substituted aromatic radical whereim fii substituted in at least one of the aryl nucle i;attached to the alkane and methane moieties of the lattertwoclasses of photoconductors which are non-leuco base materials; and also other polyarylalkanes includesby the formula:
• each of D, E and G is an aryl group and J a 'Hydro'gefi'atom,afi*alkyl rnupg'or' an aryl grou at least one of D, E and G containing an amino substituent
• the aryl groups attached to the central carbon atom being preferably phenyl groups, although naphthyl groups can also be used including substituted aryl groups containing substituents such as alkyl and alkoxy typically having 1 to 8 carbon atoms, hydroxy, halogen; ,etc.," in the ortho, meta or para positions, ortho-substitutedphenyl being preferredj
• the taryl groups can also .be joined together or cyclized to form a fluorene moiety, for example;
• the amino substituent can be represented by the formula I t x LflRz'I' wherein each R can be' an alkyl grouptypically having 1 to 8 carbonatomspa hydrogenatom, an aryl-
• v I .a (D) Photocouductors' comprising 4-diarylamino substituted chalcones having the formula:
• R and R are each phenyl radicals including substituted phenyl radicals, R2 preferably having the formula:
• Rt wherein R and R are each aryl radicals, aliphatic residues of 1 to 12 carbon atoms such as alkyl radicals pr'eferably having lto 4 carbon atoms, or hydrogen; particularly advantageous results being obtained wnenR, is a phenyl radical including a substituted phenyl. radical and where R, is diphenylaminophenyl, dijmethylamiriophe'nyl or phenyl, these materials being more fullydescribe m Fox'application U.S. Ser. No. 613,846, new U.S. Pat. 3,525,501.
• Non-ionic cycloheptenyl compounds' which maybe substitutedwith substituents such as: 2 (1) an aryl radical including substituted as well as "uni substituted aryl radicals, 1 (2) a hydroxy radical,
• D can be any of the substituents defined for E and G above and is attached to a carbon atom in the cycloheptenyl nucleus having a double bond; (R and R (R and R (R and R and (R and R are together the necessary atoms to complete a benzene ring fused to the cycloheptenyl nucleus; these compounds being more fully described in U.S. Ser. No. 654,091 filed July 18, 1967, now U.S. Pat. 3,533,786.
• a phenyl radical including a substituted phenyl radical such as a naphthyl, an aminophenyl or a hydroxyphenyl radical,
• a heterocyclic radical such as a-pyrazolyl, carbazolyl or a pyridyl radical
• D E G and 1 are each either: 1
• Y (a) a substituted phenyl radical such as a naphthyl I Especially preferred are those tetra-substituted hydrazines wherein both D and G are either substituted phenyl radicals or heterocyclic radicals. These compounds are more fully described in U.S. Ser. No. 673,962 filed Oct. 9, 1967.
• (G) Organic compounds having a 3,3'-bis-aryl-2-pyrazoline nucleus which is substituted in either five-member ring with the same or different substituents.
• the 1 and 5 positions on both pyrazoline rings can be substituted by an aryl moiety including unsubstituted as well as substituted aryl substituents such as alkoxyaryl, alkaryl, alkaminoaryl, carboxyaryl, hydroxyaryl and haloaryl.
• the 4 position can contain hydrogen or unsubstituted as well as substituted alkyl and aryl radicals such as alkoxyaryl, alkaryl, alkaminoaryl, haloaryl, hydroxyaryl, alkoxyalkyl, aminoalkyl, carboxyaryl, hydroxyalkyl and haloalkyl.
• aryl radicals such as alkoxyaryl, alkaryl, alkaminoaryl, haloaryl, hydroxyaryl, alkoxyalkyl, aminoalkyl, carboxyaryl, hydroxyalkyl and haloalkyl.
• Other photoconductors in this class are represented by the following structure:
• D D 1;, and 1; can be either a phenyl radical includmg a substituted phenyl radical such as a tolyl radical or a naphthyl radical including a substituted naphthyl radical,
• E E G G L and L can be any of the substitu ents set forth above and in addition can be either a hydrogen atom or an alkyl radical containing 1 to 8 carbon atoms.
• vinylene radical includes substituted as well as unsubstituted vinylene radicals and also includes those radicals having at least one and as many as three repeating units of vinylene groups such as wherein n is an integer of from 1 to 3.
• Groups which contain active hydrogen are well known in the art, the definition of this term being set forth in several textbooks such as Advanced Organic Chemistry, R. C. Fuson, pp. 154-157, John Wiley & Sons, 1950.
• act ve hydrogen-containing group includes those compounds encompassed by the discussion in the text book cited above and in addition includes those compounds which contain groups which are hydrolyzable to active hydrogen-containing groups.
• Typical active hydrogen-containing groups substituted on the vinylene rad cal of the triarylamine include:
• R is alkyl or aryl
• cyclic ester radicals e.g.,
• R is a cyclic alkylene radical connected to a vinylene combination such as is found in coumarin derivatives
• carboxylic acid anhydride radicals e.g., a cyclic alkylene radical connected to a vinylene combination such as is found in coumarin derivatives
• carboxylic acid anhydride radicals e.g., a cyclic alkylene radical connected to a vinylene combination such as is found in coumarin derivatives
• amido radicals e.g.,
• R is a hydrogen atom, an alkyl group or an aryl group
• active hydrogen-Containing groups include sub.- stituted and unsubstituted alkylidyne oximadoradicals.
• Photoconductors included in this class canbe represented by the following structure; a
• Ar and Ar are each a phenyl radical including a substituted phenyl radical such as a halophenyl radical, an'alkyl-phenyl radical oran aminophenyl'radical;
• (2)-Ar is an arylene radical including asubstituted arylene radical such as a phenylene radical or a naphthylene radical,
• Rf, and R are each hydrogen, a phenyl radical in- I cludinga substituted'phenyl radical-or a lower alkyl radicalpreferably having 1' to 8 carbon atoms,
• an active hydrogen-containing group such' as a carboxy radical, an acyl halide radical,-- an amido radical,; .a ;carboxylic acid anhydridef radical, an ester radical, a cyanoradical, a hydroxyradical, a
• the arylene nucleus can be substituted in any position by the vinyl or vinylene moiety.
• Ar is phenylene, particularly good results are obtained. if the substitution occurs in the para position.
• Triarylamines in which at least one ofthe aryl radicals is substituted by an active hydrogen-eontaining group.
• active hydrogen-containing groupf' has the same meaning as set forth above and againincludes those compounds encompassedby the discussion in tlie textbook and additionally includes thosejv compounds which contain groups which are hydrolyzable to active hydrogen-containing group's.
• Typical active' hydrogen containing groups which are substituted on an aryl-radical of the triarylamine include: a
• ester radicals e.g.,
• R is an alkyl or an aryl group
• lower alkylene hydroxy radicals e.g., having 1 to 8 carbon atoms.
• carboxylic acid anhydride radicals 1 v (7) lower alkylene carboxy radicals (e.g., having 2to 8 carbon atoms).
• i cyano radicals, (9) acyl halide radicals (e.g.,
• amido radicals e.g.,
• R is a hydrogen atom, an alkylgroup or an y p), .i
• I Q (a) Ar, and Ar are 'ach' a phenyl adian including a substituted phenyl radical such as a halophe'nyl radical, an alkyl phenylradical or an amino phenyl radical
• Arg isan arylene radical including a substituted arylene'radical such as a phenylene radical or anaphthylene radical
• I (c) X is an active hydrogen-containinggroup such as a carboxy radical, anacyl halidefradical, an'amidoradical, acarbox'ylic acid anhydride radical, a'ri'ester radical, a cyano radical, a semicarbozono radical, a hyradical or a phenylene carbox'y' droxy radical, an ethynyl radical, "amethylidyneoximido UZ S. Ser. 0. 706,780 filed Feb. 20,
• tionfpp; 394-95-)1and includezsilicon, germanium, tin and lead-iror'n'Group-IVa and phosphorus, arsenic, antimony and'bismuth, from Group Va. .
• These materials can be substituted in the metallo nucleus with a wide variety of substituents but at least one of the substituents must be an amino-aryl radical.
• the amino radical can be positioned anywhere on the aromatic nucleus, but best results are obtained if the aryl 'moietyis a phenyl radical having the F amino group in the 401 'paraposition.
• Typical substituents attached to the metalnucleus include thetfollowingz T QP Y J T F lIiP i si i Photoconductors included in this. class can be -repr esented by thefollowing structures; a
• E G L and Q can be:
• an aryl radical including unsubstituted as well as substituted aryl radicals such as a phenyl radical, a naphthyl radical, a dialkylamjnophenyl radical, or a diarylaminophenyl radical,
• a heterocyclic radical having 5 to 6 atoms in the hetero nucleus including at least one nitrogen atom such as a triazolyl, a pyridyl radical, etc.
• T is an amino radical such as an alkylamino radical having 1 to 8 carbon atoms or an arylamino radical such as a phenylamino radical;
• Ar is an aromatic radical such as phenyl or naphthyl
• M and M are the same or different Group IVa metals
• M is a Group Va metal
• D can be any of the substituents set forth above for E G L and Q and in addition can be a Group IVa organo-metallic radical or, when taken with E, an oxygen atom or a sulfur atom;
• J can be any of the substituents set forth above for E G L and Q and in addition can be when taken with B, an oxygen atom or'a sulfur atom. These materials are described in US. Ser. No. 650,664, filed July 3, 1967.
• organic photoconductors useful in this invention include the compounds listed below:
• the image-bearing members whether, comprised simply of a sheet of insulating'material or in-the form of an electrophotographic element, all have ,in common an extremely smooth surface towhich the electrostatic charge pattern is ,applied.
• the image-bearing member smoothness measurements is: made by thei'She'fiield Corporation of Dayton, Ohio.
• the components of the equipment are (I) a precision device in which a sheet sample is held against a smooth glass plate under an accurately weighed, precision-machined head th'ro'ughwhich a regulated stream of air flows, and (II) 'ajModular- Precisionaire Instrument which measures theflow ofair across the face of the sheet sample; Data are read in numerical units from O for extremesmoothness toi wo for rough surfaces.
• the electrostatic charge formed on the surface of the photoconductive is then selectively dissipated from the surface of the layer by imagewise exposure to light by means of a conventional exposure operation such as, for example, by a contact-printing techinque, or by lens projection of an image, and the like, to thereby form an electrostatic latent image in the photoconductive layer.
• Exposing the surface in this manner forms a pattern of electrostatic charge by virtue of the fact that light energy striking the photoconductor causes the electrostatic charge in the light struck areas to be conducted away from the surface in proportion to the intensity of the illumination in a particular area.
• the smooth surface of the image-bearing member is wetted with an electrically insulating particle-free transfer liquid.
• This liquid can be applied by any suitable means such as spraying, pouring, swabbing, squeegeeing, immersion and the like.
• Useful materials for wetting the image-bearing member include hydrocarbon liquids typically having a boiling point in the range of about 105 to 260 C. and a volume resistivity of at least about 10 ohm-cm.
• the transfer liquids should exhibit no substantial solvent action on either the image-bearing member or the receiving element. Similarly, the transfer liquid should be compatible with any liquid developing materials used to develop the transferred charge pattern.
• isoparaffinic hydrocarbons having a low dielectric constant preferably below about 2.5.
• Specific liquids which are useful include various solvents made by Humble Oil & Refining Co. and sold under the trade name of Isopar, such as Isopar C, Isopar E, Isopar G, Isopar H, Isopar K, Isopar L, Isopar M, etc. Mixtures of suitable liquids can also be utilized.
• the receiving element After application of the transfer liquid, the receiving element can be immediately placed in contact with the wetted member. However, to insure a uniform thickness of liquid over the whole surface of the element, it is often desirable to allow the liquid to partially dry for a brief period.
• the liquid layer can also be rapidly wiped with a squeegee or similar device to insure a uniform thickness of the liquid layer.
• the process of this invention can be rapidly accomplished without the drying or squeegeeing steps; however, these steps insure a greater degree of reprodncibility.
• the receiving elements useful in the present invention can be formed of a variety of sheet materials. Suitable receiving elements have an electrically insulating layer and an electrically conductive backing or support. These elements are preferably flexible and all have in common at least one electrically insulating surface which typically has a resistivity of at least about 10 ohm-cm. and which is extremely smooth. In general, this surface of the element has a Shefiield Smoothness value, as described above, in the range of O to 25 with preferred materials having a value in the range of to 10.
• Useful receiving elements can be formed using a variety of different conducting supports, for example, paper (at a relative humidity above 20 percent), aluminum foil-paper laminates; metal foils, such as aluminum foil, zinc foil, etc.; vapor deposited metal layers such as silver, nickel, aluminum and the like coated on paper or conventional photographic film bases such as cellulose acetate, polystyrene, poly(ethylene terephthalate), etc.
• Such conducting materials as nickel can be coated by vacuum deposition on transparent film supports in sufiiciently thin layers as to result in a transparent element.
• An especially useful conducting support can be prepared by coating a support material such as poly (ethylene terephthalate) with a conducting layer containing a semiconductor such as cuprous iodide dispersed in a resin. Such conducting layers are described in U.S. Pats.
• a suitable conduct ing coating can be prepared from the sodium salt of a carboxyester lactone of maleic anhydride and a vinyl acetate polymer. Conducting layers of this latter type and methods for their preparation and use are described in U.S. Pat. Nos. 3,007,901 and 3,267,807.
• the conducting support is then overcoated with a suitable electrically insulating resin to provide the requisite extremely smooth surface.
• Suitable resins for this purpose can include any of a wide variety of electrically insulating, film-forming resins.
• Typical resins useful in this invention would include polyesters, polyolfins, such as polyethylene and polypropylene, polycarbonates, polyamides, poly (alkyl methacrylates) and the like. Mixtures of various resins can be used as well as plasticized resins. The only requirements of the resins used are that they be electrically insulating, film-forming, reasonably flexible and capable of being coated so as to have the requisite surface smoothness.
• the receiving element can be opaque or transparent depending upon the type of final image desired.
• the receiving element can, of course, be wetted with the transfer liquid and then placed in contact with a dry image-bearing member. Regardless of which is wetted first, the member and element are always placed in face to face contact in the presence of an intermediate layer of transfer liquid. Intimate contact of the member and element is obtained without the application of any external pressure. In addition, no forward or reverse bias potentials are applied between the image-bearing member and the receiving element before, during or after transfer of the charge pattern. Also, the member and element do not have to be electrically grounded during transfer.
• the layer of transfer liquid is squeegeed, is allowed to partially dry or is otherwise treated or applied such that the layer is extremely thin, probably having a thickness in the range of about 1 to 5 microns. In this latter instance, images are obtainable which have a resolution of at least about lines/mm.
• An electrophotographic element is prepared by coating a layer of poly(vinyl-m-bromobenzoate-co-vinyl acetate) containing about 25% by Weight of 4,4-diethylamino-2,2'- dimethyltriphenylmethane photoconductor onto a conductive support comprising a curpous iodide conducting layer on a poly(ethylene terephthalate) film base which is coated with a terpolymer of itaconic acid, ethyl acrylate and vinylidene chloride.
• the conducting layer is overcoated with a barrier layer of cellulose nitrate.
• the photoconductive layer is coated at a wet thickness of 0.004 inch.
• the coating is allowed to dry at room temperature and further dried by placing the element in a hot-air oven with an air temperature of about 60 C. After complete drying, the element is examined and found to have an extremely smooth surface on the photoconductive layer. The Shefiield Smoothness value of this surface is about 5.
• This element is then charged using a negative corona source until the surface potential reaches a value of minus 700 volts.
• the charged element is then exposed to a negative-appearing microimage having a maximum density of 1.5 and a maximum resolution of linepairs per millimeter. The exposure is made using an 85- watt Mercury light source.
• the exposed element is then placed in contact with a receiving element comprising a.
• polyester 49,000 is a polyester obtained from Du Pont Co. and is prepared from ethylene glycol and equal amounts of dimethyl terephthalate and dimethyl isophthalate with small amounts of adipic and sebacic acids. The element is charged, exposed and developed as in Example 1 and found to have similar resolution but with lower maximum density.
• Example 3 The procedure of Example 1 is repeated several times only using an electrical potential between the conductive layer of the receiving element and the conductive layer of the photoconductive element. Forward bias potentials of from 225 to 1000 volts are used during the transfer operation with the receiving element being positive with respect to the photoconductive element. The resulting images are similar to those obtained in Example 1 with no significant change in resolution. However, unwanted density is obtained in the background image areas.
• Example 4 The procedure of Example 3 is repeated using a reverse bias potential of 225 volts during transfer with the receiving element at a negative polarity. After development, the resulting image is found to have a lower resolution with only 60 line-pairs per millimeter being obtainable.
• Example 5 The procedure of Example 1 is generally followed except that, after exposure, the photoconductive film is wetted by dipping it into a bath of Isopar G.
• Isopar G is an isoparaflinic hydrocarbon solvent having a boiling point in the range of 150 to 185 C. (Humble Oil & Refining Co.).
• the wetted image-bearing member is placed in contact with a receiving element as before and the receiving element is then carefully peeled away and developed as in Example 1. During the transfer operation, no external pressure or electrical bias potentials are applied. After developing the transferred charge image, the resolution is found to be 135 line-pairs per millimeter.
• EXAMPLE 6 The procedure in Example 5 is repeated entirely except that the receiving element is first wetted and then placed in contact with the dry image-bearing member. Similar results are obtained.
• EXAMPLE 7 The procedure of Example 6 is repeated entirely except the receiver surface is allowed to dry partially for a period of l-minute after being immersed in the transfer liquid. The partially dried receiver element is then placed in contact with the image-bearing member and carefully peeled away. The resulting image has a higher and more uniform maximum density and has a resolution of at least 150 line-pairs per millimeter.
• EXAMPLE 8 The procedure of Example 5 is repeated several times using electrical bias potentials in the range of about 500 16 and 1200 volts with the conductive layer of the receiving element being positive and that of the image-bearing member being negative. This results in an increased maximum density; however, it also results in an increased minimum density above the desirable level. In addition, the resolution is adversely affected.
• Example 9 The procedure of Example 5 is followed again only in place of the isoparafiinic hydrocarbon transfer liquid, Dow Corning Fluid 200 Silicon Oil is used, which oil has a viscosity of about 2 centistokes. The resulting image has a resolution considerably below that obtained in Example 5.
• a process as described in claim 1 including the further step of allowing said liquid to partially dry prior to contact with said receiving element.
• liquid developer is a liquid developer comprised of marking particles dispersed in a carrier liquid which is compatible with said transfer liquid.
• a process as described in claim 3 wherein the gap between said member and said element during transfer is about 1 to 5 microns.

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Cited By (12)

• 1970
  • 1970-04-02 US US25246A patent/US3672930A/en not_active Expired - Lifetime
• 1971
  • 1971-03-10 CA CA107352A patent/CA937978A/en not_active Expired
  • 1971-03-29 FR FR7110868A patent/FR2092497A5/fr not_active Expired
  • 1971-03-30 BE BE765016A patent/BE765016A/xx unknown
  • 1971-04-01 AU AU27207/71A patent/AU2720771A/en not_active Expired
  • 1971-04-19 GB GB2591671*A patent/GB1329188A/en not_active Expired

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