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 or 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
  • G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
  • G03G5/0664—Dyes
  • G03G5/0666—Dyes containing a methine or polymethine group
  • G03G5/0668—Dyes containing a methine or polymethine group containing only one methine or polymethine group
  • G03G5/067—Dyes containing a methine or polymethine group containing only one methine or polymethine group containing hetero rings

Definitions

• the process of xerography employs an electrophotographic element comprising a support material bearing a coating of a normally insulating material whose electrical resistance varies with the amount of incident actinic radiation it receives during an imagewise exposure.
• the element commonly termed a photoconductive element, is first given a uniform surface charge, generally in the dark after a suitable period of dark adaptation. It is then exposed to a pattern of actinic radiation which has the effect of differentially reducing the potential of the surface charge in accordance with the relative energy contained in various parts of the radiation pattern. The differential surface charge or electrostatic charge image remaining on the electrophotographic element is then made visible by contacting the surface with a suitable electroscopic marking material.
• marking material or toner whether contained in an insulating liquid or on a dry carrier, can be deposited on the exposed surface in accordance with either the charge pattern or the absence of charge pattern as desired.
• the deposited marking material may then be either permanently fixed to the surface of the sensitive element by known means such as heat, pressure, solvent vapor, or the like, or transferred to a second element to which it may similarly be fixed.
• the electrostatic charge image can be transferred to a second element and developed there.
• Various photoconductive insulating materials have been employed in the manufacture of electrophotographic elements. For example, vapors of selenium and vapors of selenium alloys deposited on a suitable support and particles of photoconductive zinc oxide held in a resinous, film-forming binder have found wide application in present-day document copying applications.
• organic photoconductors comprising the materials described are inherently light sensitive, their degree of sensitivity is usually low and in the short wavelength portion of the spectrum so that it is common practice to add materials to increase the speed and to shift the sensitivity toward the longer wavelength portion of the visible spectrum.
• Increasing the speed and shifting the sensitivity of such systems into the visible region of the spectrum has several advantages; it makes available inexpensive and convenient light sources such as incandescent lamps; it reduces exposure time; it makes possible the recording of a wide range of colors in proper tonal relationship, and allows projection printing through various optical systems.
• sensitizers By increasing the speed through the use of sensitizers, photoconductors which would otherwise have been unsatisfactory are useful in processes where high speeds are required such as document copying.
• sensitizing dyes because they are highly colored, they impart undesirable discoloration to the entire photoconductive element.
• an image developed directly on the surface of the element can be viewed only with great difficulty because of low visual contrast.
• such an element bearing a developed image is generally unsuitable for use as a master for the making of additional reproductions.
• photoconductive compositions containing a photoconductor and a dinitroarylmethine dye as a sensitizer for the photoconductive composition.
• the methine dye is generally terminated by a fiveto six-membered heterocyclic nucleus containing at least one oxygen, sulfur, selenium or nitrogen atom.
• This terminal heterocyclic nucleus can be substituted by various groups such as alkyl, aryl, alkenyl, halogen, nitro, etc., or can have other cyclic groups fused to one side thereof.
• dinitroarylmethine dyes are incorporated into photoconductive compositions, an enhanced sensitization effect is realized.
• Photoconductive compositions which do not contain the sensitizers of this invention frequently do not produce good quality images when used in element form in an electrophotographic process.
• the sensitizing dyes of this invention are rapidly photobleachable by actinic radiation such as radiation from a cool light source.
• Fluorescent sources and incandescent tungsten sources are substantially equally effective.
• a light exposure of at least l0 foot-candle-seconds is sufficient to cause substantial bleaching (i.e., an increase in transmittance of at least 25 percent). Little or no practical advantage is obtained in using light exposures in excess of 10'' foot-candle-seconds.
• the preferred dinitroarylmethine-sensitizing dyes of this invention have the following formula:
• aralkyl e.g., benzyl, phenethyl, etc.
• alkylaminoalkyl e.g., methylaminopropyl
• methylaminoethyl, etc, and also including dialkylaminoalkyl e.g., diethylaminoethyl, dimethylaminopropyl, dipropylamino-octyl, etc., gv arylaminoalkyl, e.g., phenylaminoalkyl, di-phenwherein R is hydroxy, etc., hydrogen, aryl, e.g., phenyl, naphthyl, etc., lower alkyl having one to eight carbon atoms e.g., methyl, ethyl, propyl, etc., amino including substituted amino e.g., diloweralkylamino, lower alkoxy having one to eight carbon atoms e.g., butoxy, methoxy, etc., aryloxy, e.g., phenoxy, naphthoxy, etc.,
• a cycloalkyl group having four to eight carbon atoms in the cyclic nucleus e.g., cyclobutyl, cyclohexyl, cyclopentyl, etc., including a substituted cycloalkyl group such as a. alkoxycycloalkyl e.g., ethoxycy'clohexyl, methoxycyclobutyl, propoxycyclohexyl, etc.,
• aryloxycycloalkyl e.g., phenoxycyclohexyl, naphthoxycyclohexyl, phenoxycyclopentyl, etc.
• aminocycloalkyl e.g., aminocyclobutyl
• hydroxycycloalkyl e.g., aminocyclohexyl, hydroxycyclopentyl, hydroxycyclobutyl, etc.
• arylcycloalkyl e.g., phenylcyclohexyl, phenylcyclobutyl, etc.
• alkylaminocycloalkyl e.g., methylaminocyclohexyl
• methylaminocyclopentyl, etc. and also including dialkylaminocycloalkyl e.g., diethylaminocyclohexyl, dimethylaminocyclobutyl, dipropylaminocyclooctyl, etc.,
• arylaminocycloalkyl e,g., phenylaminocyclohexy
• nitrocycloalkyl e.g., nitrocyclobutyl, nitrocyclohexyl
• cyanocycloalkyl e.g., cyanocyclohexyl, cyanocyclobutyl, cyanocyclopentyl, etc.
• halocycloalkyl e.g., chlorocyclohexyl, bromocyclopen' tyl, chlorocyclooc'tyl, etc.
• a hcterocyclic group including a substituted heterocyclic group containing fiveto six-members in the heteronucleus and including at least one sulfur, selenium, oxygen or nitrogen atom such as a thienyl group e.g., a benzothienyl group, a pyrrolyl group, eg, a nitropyrrolyl group, a pyrrolidinyl group e.g., a prolyl group, a pyrrolinyl group, a benzopyrrolyl group e.g., an indolyl group, a carbazolyl group, a furyl group e.g., a furfuryl group, a benzofuryl group etc., a pyridyl group, e.g., a halopyridyl group, an aminopyridyl group, a hydroxypyridyl group,
• an aryl group e.g., phenyl, naphthyl, anthryl, fluorenyl,
• aryl group such as a. alkoxyaryl, e.g., ethoxyphenyl, methoxyphenyl,
• aryloxyaryl e.g., phenoxyphenyl, naphthoxyphenyl,
• hydroxyaryl e.g., hydroxyphenyl, hydroxynaphthyl
• alkylaminoaryl e.g., methylaminophenyl
• methylaminonaphthyl, etc. and also including dialkylaminoaryl, e.g., diethylaminophenyl, dipropylaminophenyl, etc.,
• arylaminoaryl e.g., phenylaminophenyl, diphenylaminophenyl, N-phenyl-N-ethylaminophenyl, N- phenyl-N-chloroaminophenyl, naphthylaminophenyl,
• nitroaryl e.g,, nitrophenyl, nitronaphthyl, nitroanthryl,
• cyanoaryl e.g., cyanophenyl, cyanonaphthyl
• haloaryl e.g., chlorophenyl, bromophenyl,
• alkaryl e.g., totyl, ethylphenyl, propyl, naphthyl, etc.;
• an unsaturated alkyl group having two to 18 carbon atoms such as a. alkenyl e.g., vinylidene, propylidene, butyl-idene, etc.,
• alkynyl e.g., ethynyl, l-propynyl, l-butynyl, l-isopentynyl,etc.
• alkadienyl e.g., butadienyl (1,3), pentadienyl (1,3)
• aralkenyl e.g., styryl, 3-phenylpropylidene, 4-phenylbutylidene, etc.
• aralkynyl e.g., phenethynyl, 3-phenylpropynyl, 4-phenylbutynyl, etc.
• aralkadienyl e.g., 4-phenyl-butadienyl (1,3), Spentadienyl (1,3), etc., or
• Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus containing five to six atoms in the heterocyclic ring, which nucleus can contain at least one additional hetero atom such as oxygen, sulfur, selenium or nitrogen, Le, a nucleus of the type used in the production of cyanine dyes, such as the following representative nuclei: a thiazole nucleus, e.g., thiazole,4methylthiazole, 3-ethylthiazole, 4-phenylthiazole, S-methylthiazole, S-phenylthiazole, 4,5- dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)thiazole,
• benzothiazole 4-chlorobenzothiazole, 4- or 5- nitrobenzothiazole, S-chlorobenzothiazole, 6- chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenzothiazole, 6-methylbenzothiazole, 6-nitrobenzothiazole, 5-bromobenzothiazole,
• 6-bromobenzothiazole 5-chloro-6-nitrobenzothiazole, 4- phenylbenzothiazole, 4-m ethoxybenzothiazole, S-methoxybenzothiazole, o-methoxybenzothiazole, 5-
• iodobenzothiazole (a-iodobenzothiazole, 4-ethoxybenzothiazole, 5 -ethoxybenzothiazole, a tetrahydrobenzothiazole nucleus, 5 ,6-dimethoxybenzothiazole, 5,6-methylenedioxybenzothiazole, S-hydroxybenzothiazole, o-hydroxybenzothiazole, a-naphthothiazole, B-naphthothiazole, B,B-naphthothiazole, S-methoxy-fiL/inaphtho-thiazole, 5-ethoxy-B-naphthothiazole, 8-methoxy-anaphthothiazole, 7-methoxy-a-naphthothiazole, 4 -methoxythianaphtheno-7',6',4,5-thiazole, 3-ethyl-2,3-
• Typical compounds which belong to the herein described general class of sensitizing dyes include the following:
• Electrophotographic elements of the invention can be prepared with any photoconductive compound and the sensitizers of this invention in the usual manner, i.e., by blending a dispersion or solution of the photoconductive compound together with a binder, when necessary or desirable, and coating or forming a self-supporting layer with the photoconductive composition.
• a suitable amount of the sensitizing compound is mixed with the photoconductive coating composition so that, after thorough mixing, the sensitizing compound is uniformly distributed throughout the desired layer of the coated element.
• the amount of sensitizer that can be added to a photoconductor-incorporating layer to give ef fective increases in speed can vary widely. The optimum concentration in any given case will vary with the specific photoconductor and sensitizing compound used.
• an appropriate sensitizer is added in a concentration range from about 0.000] to about 30 percent by weight of the film-forming coating composition.
• a sensitizer is added to the coating composition in an amount from about 0.005 to about 5.0 percent by weight of the total coating composition.
• the sensitizers of this invention improve the electrical speeds of compositions containing a wide variety of photoconductors, including inorganic photoconductors such as zinc oxide, titanium dioxide, cadmium sulfide and the like, organic photoconductors including organometallic photoconductors and mixtures thereof. Also, polymeric photoconductors can be used.
• photoconductors including inorganic photoconductors such as zinc oxide, titanium dioxide, cadmium sulfide and the like, organic photoconductors including organometallic photoconductors and mixtures thereof.
• polymeric photoconductors can be used.
• Arylamine photoconductors including substituted and unsubstituted arylamines, diarylamines, nonpolymeric triarylamines and polymeric triarylamines such as those described in U.S. Pats. Nos. 3,240,597 and 3,180,730.
• Z represents a mononuclear or polynuclear monovalent aromatic radical, either fused or linear (e.g., phenyl, naphthyl, biphenyl, etc.); or a substituted monovalent aromatic radical wherein said substituent can comprise a member, such as an acyl group having from one to about six carbon atoms (e.g., acetyl, propionyl, butyryl, etc.), an alkyl group having from one to about six carbon atoms (e.g., methyl, ethyl, propyl, butyl, etc.), an alkoxy' group having from one to about six carbons atoms (e.g., methoxy, propoxy, pentoxy, etc.), or a nitro group; O can represent a hydrogen atom or an aromatic amino group, such as ZNH; b represents an integer from one to about 12, and L represents a hydrogen atom, a monon
• Polyarylalkane photoconductors including leuco bases of diaryl or triarylmethane dye salts, 1,1 ,l-triarylalkanes wherein the alkane moiety has at least two carbon atoms and tetraarylmethanes having an amino group substituted in at least one of the aryl nuclei attached to the alkane and methane moieties of the latter two classes of photoconductors which are nonleuco base materials; and also other polyarylalkanes included by the formula:
• each of D, E and G is an aryl group and J is a hydrogen atom, an alkyl group, or an aryl group, 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 one to eight carbon atoms, hydroxy, halogen, etc., in the ortho, meta or para positions, ortho-substituted phenyl being preferred; the aryl groups can also be joined together or cyclized to form a fluorene moiety, for example; the amino substituent can be represented by the formula wherein each R can be an alkyl group typically having one to eight carbon atoms, a hydrogen atom, an aryl group, or together the necessary atoms to form a heterocyclic amino group typically having five to six atoms in the ring such as morpholino,
• R and R are each phenyl radicals including substituted phenyl radicals, R preferably having the formula:
• R and R are each aryl radicals, aliphatic residues of one to 12 carbon atoms such as alkyl radicals preferably having one to four carbon atoms, or hydrogen; particularly advantageous results being obtained when R is a phenyl radical including a substituted phenyl radical and where R is diphenylaminophenyl, dimethylaminophenyl or phenyl, these materials being more fully described in Fox U.S. application, Ser. No. 613,846, filed Feb. 3, 1967, now U.S. Pat. No. 3,526,501.
• substituents such as:
• heterocyclic radical having five to six atoms in the heterocyclic nucleus and at least one hetero nitrogen atom, and including substituted and unsubstituted heterocyclic radicals, and
• an oxygen containing radical having a structure such that the resultant cycloheptenyl compound is a sym metrical ether
• 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
• an amino radical including substituted as well as unsubstituted amino radicals such as an alkylamino or a phenylalkylamino radical,
• a heterocyclic radical such as a pyrazolyl, carbazolyl or a pyridyl radical
• tetra-substituted hydrazines include those having the following formula:
• D, E, G and J are each either:
• a substituted phenyl radical such as a naphthyl radical, an alkyl phenyl radical, a halophenyl radical, a hydroxyphenyl radical, a haloalkylphenyl radical or a hydroxyalkylphenyl radical, or
• J and E can also be c. an unsubstituted phenyl radical.
• 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 oneand fivepositions 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 J and J can be either a phenyl radical including a substituted phenyl radical such as a tolyl radical or a naphthyl radical including a substituted naphthyl radical, E E G 6;
• L and L can be any of the substituents set forth above and in addition can be either a hydrogen atom or an alkyl radical containing one to eight carbon atoms.
• H Triarylamines in which at least one of the aryl radicals is substituted by either a vinyl radical or a vinylene radical having at least one active hydrogen-containing group.
• 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.
• active hydrogen-containing group includes those compounds encompassed by the discussion in the textbook 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 radical 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 is coumarin derivatives
• amido radicals wherein R is a hydrogen atom, an alkyl group or an aryl group).
• Other active hydrogen-containing groups include substituted and unsubstituted alkylidyne oximido radical s.
• Photoconductors included in this class can be represented by the following structure:
• an active hydrogen-containing group such as a carboxy radical, an acyl halide radical, an amido radical, a carboxylic acid anhydride radical, an ester radical, a cyano radical, a hydroxy radical, a semicarbazono radical, an ethynyl radical, or a methylidyne oximido radical, or
• n is an integer of l to 3.
• the arylene nucleus can be substituted in any position by the vinyl or vinylene moiety. However, when Ar; is phenylene, particularly good results are obtained if the substitution occurs in the para position.
• Triarylamines in which at least one of the aryl radicals is substituted by an active hydrogen-containing group.
• active hydrogen-containing group has the same meaning as set forth above and again includes those compounds encompassed by the discussion in the textbook and additionally includes those compounds which contain groups which are hydrolyzable to active hydrogen-containing groups.
• Typical active hydrogen-containing groups which are substituted on an aryl radical of the triarylamine include:
• lower alkylidyne oximido radicals having one to eight carbon atoms including substituted alkylidyne oximido radicals (e.g., (IJ NOH wherein Rzu R is hydrogen or a lower alkyl radical),
• arylene carboxy radicals including substituted arylene carboxy radicals wherein D and E are phenyl or lower alkyl radicals.
• Photoconductors included in this class can be represented by the following structure:
• Ar and Ar are each a phenyl radical including a substituted phenyl radical such as a halophenyl radical,'an alkyl phenyl radical or an amino phenyl radical,
• Ar is an arylene radical including a substituted arylene radical such as a phenylene radical or a naphthylene radical, and
• X is an active hydrogen-containing group such as a carboxy radical, an acyl halide radical, an amido radical, a carboxylic acid anhydride radical, an ester radical, a cyano radical, a semicarbazono radical, a hydroxy radical, an ethynyl radical, a methylidyne oximido radical or a phenylene carboxy radical.
• the metallic substituents of this class of organic photoconductors are Group No or Group Va metals in accordance with the Periodic Table of the Elements (Handbook of Chemistry and Physics, 38th edition, pp. 394-) and include silicon, germanium, tin and lead from Group [Va 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 moiety is a phenyl radical having the amino group in the 4 or para position.
• Typical substituents attached to the metal nucleus include the followl. a hydrogen, sulfur or oxygen atom,
• an aryl radical including unsubstituted as well as substituted aryl radicals such as aminoaryl, alkylaryl and haloaryl,
• an oxygen-containing radical such as an alkoxy or aryloxy radical
• an amino radical including unsubstituted and substituted amino radials such as monoand diarylamino and monoand dialkylamino radicals,
• Photoconductors included in this class can be represented by the following structures:
• 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 dialkylaminophenyl radical, or a diarylaminophenyl radical,
• R and R can be hydrogen atoms or alkyl radicals having one to eight carbon atoms, or
• a heterocyclic radical having five to six 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 lVa 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 N11 organometallic radical or, when taken with E, an oxygen atom or a sulfur atom;
• .l can be any of the substituents set forth above for E G L and Q and in addition can be when taken with E, an oxygen atom or a sulfur atom.
• organic photoconductors useful in this invention include the compounds listed below:
• Materials of this type comprise styrene-butadiene copolymers; silicone resins; styrene-alkyd resins; silicone-alkyd resins; soya-alkyd resins; poly(vinyl chloride); poly(vinylidene chloride); vinylidene chloride-acrylonitrile copolymers; poly(vinyl acetate); vinyl acetate-vinyl chloride copolymers; poly(vinyl acetals), such as poly(vinyl butyral); polyacrylic and methacrylic esters, such as poly(methy methacrylate), poly(n-butyl methacrylate), poly(isobuty] methacrylate), etc.; polystyrene; nitrated polystrene; polymethylstyrene; isobutylene polymers; polyesters, such as copoly[ethylene-co-alkylenebis(alkyleneoxyaryl)phenylenedicarboxylate];
• styrene-alkyd resins can be prepared according to the method described in US. Pat. Nos. 2,361,019 and 2,258,423.
• Suitable resins of the type contemplated for use in the photoconductive layers of the invention are sold under such tradenames as Vitel PE-lOl, Cymac, Piccopale 100, Saran. F220, Lexan and Lexan 145.
• Other types of binders which .can be used in the photoconductive layers of the invention include such materials as paraffin, mineral waxes, etc. Also, mixtures of these binders can be used.
• Solvents useful for preparing coating compositions with the photoconductors of the present invention can include a wide variety of organic solvents for the components of the coating composition.
• organic solvents for the components of the coating composition.
• benzene; toluene; acetone; 2-butanone; chlorinated hydrocarbons such as methylene chloride; ethylene chloride; and the like; others, such as tetrahydrofuran and the like or mixtures of such solvents can advantageously be employed in the practice of this invention.
• the photoconductor substance is an amount equal to at least about 1 weight percent of the coating composition.
• the upper limitinthe amount of photoconductor substance present can be widely varied'in accordance with usual practice, In those cases where a binder is employed, it is normally required that the photoconductor substance be present in an amount from about 1 weight percent of the coating composition to about 99 weight percent of the coating composition.
• a preferred weight range for the photoconductor substance in the coating composition is from about weight percent to about 60 weight percent.
• Coating thicknesses of the photoconductive composition on a support can vary widely. Normally, a coating in the range of about 0.001 inch to about 0.01 inch before drying is useful for the practice of this invention. The preferred range of coating thickness was found to be in the range from about 0.002 inch to about 0.006 inch before drying although useful results can be obtained outside of this range.
• Suitable supporting materials for the photoconductive layers of the present invention can include any of a wide variety of electrically conducting supports, for example, various conducting papers; aluminum-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 or aluminum on conventional film supports such as cellulose acetate, poly(ethylene terephthalate), polystyrene and the like conducting supports.
• An especially useful conducting support can be prepared by coating a support material such as poly(ethylene terephthalate) with a layer containing a semiconductor dispersed in a resin. Such conducting layers both with and without insulating barrier layers are described in US. Pat. No. 3,245,833.
• a suitable conducting coating can be prepared from the sodium salt of a carboxyester lactone of a maleic anhydride-vinyl acetate copolymer.
• Such kinds of conducting layers and methods for their optimum preparation and use are disclosed in US. Pat. Nos. 3,007,901, 3,245,833 and 3,267,807.
• the elements of the present invention can be employed in any of the well-known electrophotographic processes which require photoconductive layers.
• One such process is the aforementioned xerographic process.
• the electrophotographic element is given a blanket electrostatic charge by placing the same under a corona discharge which serves to give a uniform charge to the surface of the photoconductive layer. This charge is retained by the layer owing to the substantial insulating property of the layer, i.e., the low conductivity of the layer in the dark.
• the electrostatic charge formed on the surface of the photoconducting layer is then selectively dissipated from the surface of the layer by exposure to light through an image-bearing transparency by a conventional exposure operation such as, for example, by contact-printing technique, or by lens projection of an image, etc., to form a charge image in the photoconducting layer.
• a charge pattern is created by virtueof the fact that light causes the charge to be conducted away in proportion to the intensity of the illumination in a particular area.
• the charge pattern remaining after exposure is then developed, i.e., rendered visible, by treatment with a medium comprising electrostatically attractable particles having optical density.
• the developing electrostatically attractable particles can be in the form of a dust, e.g., powder, a pigment in a resinous carrier, i.e., toner, or a liquid developer may be used in which the developing particles are carried in an electrically insulating liquid carrier.
• a dust e.g., powder
• a pigment in a resinous carrier i.e., toner
• a liquid developer may be used in which the developing particles are carried in an electrically insulating liquid carrier.
• the present invention is not limited to any particular mode of use of the new electrophotographic materials, and the exposure technique, the charging method, the transfer (if any), the
• developing method, and the fixing method as well as the material used in these methods can be selected and adapted to the requirements of any particular technique.
• Electrophotographic materials according to the present invention can be applied to reproduction techniques wherein different kinds of radiation, i.e., electromagnetic radiations as well as nuclear radiations can be used. For this reason, it is pointed out herein that although materials according to the invention are mainly intended for use in connection with methods comprising an exposure, the term electrophotography wherever appearing in the description and the claims, is to be interpreted broadly and understood to comprise both xerography and xeroradiography.
• Example 1 A composition in the form of a dope consisting of the following materials is coated at a wet thickness of 0.004 inch on a poly(ethylene terephthalate) film support having a conducting layer of the sodium salt of butyl ester lactone made from a vinyl acetate-maleic anhydride copolymer as in Example 1 of US. Pat. No. 3,260,706;
• the surface of the photoconductive layer so prepared is charged to a potential of about +600 volts under a corona charger.
• the layer is then covered with a transparent sheet bearing a pattern of opaque and light-transmitting area and exposed to the radiation from an incandescent lamp with an illumination intensity of about 75 metercandles for 12 seconds.
• the resulting electrostatic charge image is developed by cascading over the surface of the layer negatively charged black thermoplastic toner particles on glass bead carriers.
• the background area of the reproduction is highly colored and is very difficult to view.
• the developed image bearing element is then exposed to the radiation from a 500 watt G.E. lamp (Number PH/RFL2) at a distance of ten inches for 25 seconds.
• the background color is bleached to a pale yellow and the developed image has a substantially improved visual contrast.
• Example 2 Several other sensitizing dyes are used in electrophotographic elements prepared in the manner described in Example 1. After exposure and development, the background area of each of the elements is of substantial coloration making the image portions difficult to view. The elements are then exposed to a 500watt source at a distance of 10 inches for the times set forth in the following Table. At the end of the exposure period substantially all of the background coloration is removed. Photoconductor A in the following Table is triphenylamine while Photoconductor B is the one employed in Example 1.
• Example 3 Example 1 is repeated except the photoconductive coating composition contains the following:
• the charge image is developed with a xerographic liquid developer.
• the resultant image is of very low contrast due to substantial coloration in background areas.
• the element is then bleached by subjecting it to a SOO-watt light source for 25 seconds at a distance of inches. The coloration in the background areas is virtually totally removed and the contrast is greatly improved.
• Example 4 Example 3 is repeated except the sensitizer is omitted. No developable electrostatic charge image is obtained.
• An electrophotographic element comprising a support having coated thereon a layer of a photoconductive composition comprising a photoconductor and as a sensitizer a dinitrophenylmethine dye terminated by a 5- to 6-membered heterocyclic nucleus of the type used in cyanine dyes containing at least one nitrogen atom.
• An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising an organic photoconductor and a sensitizer for said photoconductive composition having the formula:
• R is selected from the group consisting of hydrogen, an alkyl group, an alkenyl group, an aryl group and a heterocyelic group having five to six atoms in the hetero nucleus including at least one atom selected from the group consisting of sulfur, selenium, oxygen, and nitrogen,
• Z represents the atoms necessary to complete a 5- to 6- membered heterocyclic nucleus, which nucleus includes at least one atom selected from the group consisting of sulfur, selenium, oxygen, and nitrogen, and
• n is an integer of l or 3.
• An electrophotographic element comprising a support having coated thereon a layer of a photoconductive composition comprising:
• a film-forming polymeric binder for said photoconductor b. a film-forming polymeric binder for said photoconductor and c. 0.005% to about 5% by weight based on said photoconductive composition of a sensitizer comprising 2(2.4- dinitrobenzylidene)-3-ethyl-2,3-dihydrothiazolo[4,5- ]quinoline.
• An electrophotographic element comprising a support having coated thereon a layer of a photoconductive composition comprising: i
• a film-forming polymeric binder for said photoconductor b. a film-forming polymeric binder for said photoconductor and c. 0.005 percent to about 5 percent by weight based on said photoconductive composition of a sensitizer comprising l,3-diallyl-6-ehloro-2-( 2,4dinitrobenzylidene)- l ,2- dihydroimidazol4,5-bl-quinoxaline.
• An electrophotographic element comprising a support having coated thereon a layer of a photoconductive composition comprising:
• a film-forming polymeric binder for said photoconductor b. a film-forming polymeric binder for said photoconductor and c. 0.005 percent to about 5 percent by weight based on said photoconductive composition of a sensitizer comprising 6-chloro-2-(2,4-dinitrobenzylidene)-l .3-diethyl-2.3- dihydro-lH-imidazol4,5-bl-quinoxaline.
• An electrophotographic element comprising a support having coated thereon a layer of a photoconductive composi-- tion comprising:
• a film-forming polymeric binder for said photoconductor and c. 0.005% to about 5% by weight based on said photoconductive composition of a sensitizer comprising 2-(2,4- dinitrobenzylidenc)-l ,3-diethyll ,2-dihydroimidazol4,5- b]quinoxaline.
• An electrophotographic element comprising a support having coated thereon a layer of a photoconductive composition comprising:
• a film-forming polymeric binder for said photoconductor b. a film-forming polymeric binder for said photoconductor and c. 0.005 percent to about 5 percent by weight based on said photoconductive composition of a sensitizer comprising 2-(2,4-dinitrobenzylidene)-1,3,3-trimethyl-l ,2-dihydro- 3H-pyrrolol2,3-bl-pyridine.
• a photoconductive composition comprising a photoconductor and as a sensitizer a dinitrophenylmethine dye terminated by a 5 to 6 membered heterocyclic nucleus of the type used in cyanine dyes containing at least one nitrogen atom.
• composition of claim 14 wherein the photoconductor is an organic compound.
• composition of claim 14 further comprising a polymeric film-forming binder.
• a process for bleaching an image-bearing electrophotographic element having a layer ofa photoconductive composition containing as a sensitizer a dinitrophenylmethine dye ter-- minated by a 5- to 6-membered heterocyclic nucleus of the type used in cyanine dyes containing at least one nitrogen atom comprising the step of subjecting the element to actinic radiation to which said dye is sensitive to substantially bleach said dye.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Photoreceptors In Electrophotography (AREA)
• Plural Heterocyclic Compounds (AREA)

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Cited By (16)

Citations (4)

• 0
  • BE BE757066D patent/BE757066A/fr unknown
• 1969
  • 1969-10-03 US US863691A patent/US3647433A/en not_active Expired - Lifetime
• 1970
  • 1970-09-04 CA CA092341A patent/CA934205A/en not_active Expired
  • 1970-09-25 DE DE2047383A patent/DE2047383C3/de not_active Expired
  • 1970-10-01 GB GB4682170A patent/GB1321678A/en not_active Expired
  • 1970-10-02 FR FR7035637A patent/FR2064910A5/fr not_active Expired
  • 1970-10-02 AU AU20652/70A patent/AU2065270A/en not_active Expired
  • 1970-10-03 JP JP45086554A patent/JPS492636B1/ja active Pending

Patent Citations (4)

Non-Patent Citations (1)

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