Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
  • C09B23/10—The polymethine chain containing an even number of >CH- groups
  • C09B23/105—The polymethine chain containing an even number of >CH- groups two >CH- 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
  • G03G5/06—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
  • G03G5/0672—Dyes containing a methine or polymethine group containing two or more methine or polymethine groups
  • G03G5/0674—Dyes containing a methine or polymethine group containing two or more methine or polymethine groups containing hetero rings

Definitions

• ABSTRACT A novel sensitizer effectively sensitizing an organic photoconductor for electrophotography comprising the dimerized cyanine dye having a carbazole nucleus represented by the following general formula SENSITIZERS FOR ELECTROPHOTOGRAPHY [75] Inventors: Syu Watarai; Yoshio Seoka;
• R represents a hydrogen atom; an alkyl group having 1-5 carbon atoms; an alkyl group substituted by a halogen atom, a hydroxyl group or a cyano group; or an acyl group substituted by a halogen atom, a hydroxyl group, or a cyano group;
• R represents -(CH (where n is a positive integer of 2 to 6) or CH R represents a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1-5 carbon atoms.
• OR, or COOR where R is an alkyl group having 1-5 carbon atoms); andX represents an anion residue.
• the present invention relates to a sensitizer for an electrophotograhic photosensitive material comprising 5 an organic compound as the photoconductor.
• polyvinyl heterocylic compounds typified by poly-n-vinylcarbazole, polynuclear aromatic vinyl polymers such as polyvinyl anthracene; and other low molecular weight compounds having a heterocyclic ring such as an oxazole nucleus, a thiazole nucleus, and the like have been used as photoconductors for electophotography, but they themselves have sufficient sensitivity.
• the present invention has as its object the provision of a novel sensitizer capable of improving the sensitivity and the sensitive wave length region of such organic photoconductors by additon thereto.
• the sensitizer of this invention is a dimerized cyanine dye having a carbazole nucleus represented by the following general formula I:
• R represents a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1-5 carbon atoms, OR, or -COOR (where R is an alkyl group having l-5 carbon atoms); representative of these alkyl groups being methyl, ethyl, propyl butyl or pentyl groups; representatives of the halogen atoms being a chrorine, bromine or iodine atom; and representative of the acyl groups, are those of the formula R CO- (wherein R is an alkyl group having 1 to 3 carbon atom, benzyl or toluyl group); and X represents an anion residue, i.e., an anion residue capable of forming a cyanine salt as is generally used in the cyanine dye art.
• X can be organic or inorganic. Typical representatives of X are halogen atoms such as Cl, Br, 1, materials such as BF ClO 5 5 and the like. X is not
• an acyl group substituted by a halogen atom, a hydroxyl two cyanine structures in one molecule has not been known.
• the inventors succeeded in synthesizing a dye having two cyanine structures in one molecule by dimerizing an indoline derivative which is the nucleus group, or a cyano group; R represents CH (n is 45 forming a yanine dye.
• R R and K have the same significance as in general formula 1, R being a bonding group having the action of forming the dimer by bonding the nitrogen atom.
• the 2,3,3-trimethylindolenine derivative used as a raw material in the above reaction are know and largely produced as intermidates for cyanine dyes and other dyes.
• the alkyl dihalide and xylylene halide (X-R- -X) used in the above reaction is readily available.
• two mols of a compound of group I can be reacted with one mol of an alkyl dihalide at a temperature of from about 80 to 150C at normal pressure for about 2 to hours.
• the neutralization then is performed with an alkali material, most commonly sodium hydroxide.
• the dimerized quaternary salt is insoluble in water, it is dissolved by heating to about 80C and after the dissolution the alkali (basic) material is added to raise the pH to greater than 7.
• the exact conditions of neutralization merely follow neutralization conditions for similar materials known in the prior art.
• a solvent can be used if desired, but it is not necessary.
• a solvent is used, excellent results are obtained when the solvent is from about one half to five times the weight of the reactants.
• the crystals have an absorption at 1635 cm based on an exo-methylene group (shown by infrared absorption spectra).
• N,N'-xylylenebis-( 3 ,3-dimethyl-2- methyleneindoline) is prepared, in another example, by 1 heating compound No. l, (2,3,3-trimethylindolenine) and compound No. 21, (xylylene chloride) in toluene to quaternarize the former.
• the quaternary salt is new tralized with alkali.
• the compound has a melting point of 137C.
• the formylation is preferably conducted at a pressure of 1 atm. pressure, a temperature of 40100C and over a time of 1-10 hours.
• I to 3 mols of POCL is preferred to 1 mol of carbazole, in combination with l.520 mols of DMF being preferred to 1 mol of carbazole.
• a solvent is not necessary when DMF is used, but a solvent is used when N-MFA is used, for example as described in Experiment 1 below.
• EXPERIMENT 2 The case of R C 14 127 g of phosphorus oxychloride was placed in a three-necked flask and 100 ml of N,N-dimethylformamide was added dropwise thereto at 15C with stirring. A solution of 122 g of N- ethylcarbazole in 100 ml of N,N-dimethylformamide was added dropwise to the mixture at room temperature. Then, after stirring the resultant mixture while heating for 5 hours at 50C, the mixture was allowed to stand overnight. When the reaction product was poured into a large amount of water and the solution was neutralized with an aqueous NaHCO solution, a yellow-white precipitate was formed. By recrystallizing the precipitate from ethyl alcohol, 9-ethyl-3- formylcarbazole having a melting point of 89C. was obtained. All of the above procedures were performed at normal pressure.
• the dye having two cyanine structures in one molecule which is the dye used in this invention can be produced by any one of the following two methods:
• the dye is prepared by heating the dimer (bisindolenium salt) quaternarized by the reaction of an indolenine and the alkyl dihalide as described above together with formylated carbazole in a dehydrated solvent such as acetic anhydride.
• a dehydrated solvent such as acetic anhydride.
• dimer bisindolenium salt
• a solvent can be used in an amount of about 5 to by weight, based on the total weight of reactants. Additional examples of the solvents used in this reaction are N,N-dimethyl formamide, dimethyl sulfoxide and hexmethylphosphoamide.
• the dye is prepared by treating the bisindolenium salt with an alkali to form a Z-methyleneindoline dimer and the dimer then reacted in the presence of formylcarbazole and an acid.
• alkali materials are sodium and potassium hydroxide,
• the alkali should be used in a molar excess with respect to the bisindolenium salt.
• 1 mol of the dimer to 2 mols of the carbazole permits the reaction to proceed smoothly, especially when more than 2 mols of acid is present per mol of dimer.
• the reaction proceeds smoothly at normal pressure and at a temperature of from about 50C to the boiling point of the solvent used, with about 1 to about 6 hours insuring complete reaction.
• Typical of the acids used are hydrogen halide, such as hydrogen chloride, hydrochloric acid, hydrogen bromide, boron fluoride, perchloric acid, p-toluene sulfonic acid and the like.
• solvents include cyclic ethers such as tetrahydrofran diorxanes, alcohols having from 1 to 4 carbon atoms such as methanol, ethanol propanol, butanols; aromatic hydrocarbons such as benzene, toluene, etc.
• reaction product was poured into an aqueous 10% by weight perchloric acid solution in slight excess over the carbazole (generally in an amount of 1-1.2 mol to the carbazole) and then recovered as the perchlorate to give 1.2 g of the dye.
• the absorption maximum wave length of the product was at 533 my. in chloroform.
• the compound thus produced corresponds to the compound of general formula I wherein R is an ethyl group, R is CH R is H, and X is C10 SYNTHESIS II
• the dye corresponding to the compound of general formula I wherein R is an ethyl group, R is R is H and X is C10 was produced from N,N'- xyly1enebis(3,3-dimethyl-2-methyleneindoline) and N-ethyl-3-formylcarbazole.
• the absorption maximum wave length of the dye was at 544 mp. in chloroform.
• the dye is purified by extraction, e.g., the cyanine dye from which insoluble matter in chloroform has been removed is generally used, although a small amount of impurities may be contained in the dye.
• the impurities may be those having only one cyanine structure due to the incomplete of reaction and having an acid moiety at the unreacted 2- methylene indoline moiety.
• the dimer cyanine dye having a carbazole nucleus thus obtained shows an effective sensitizing effect for various organic photoconductors.
• the amount of the dimer cyanine dye can be about 0.01 to about by weight, based on the organic photoconductor weight.
• the most preferred range is from 0.1 to 0.5% by weight, based on the organic photoconductor weight.
• the dye is usually dissolved in a solvent and then mixed with the organic photoconductor.
• the organic photoconductors to which the sensitizer of this invention is added can be treated by an ordinary electrophotographic method, e.g., the photoconductors described in US. Pat. Nos. 2,221,776; 2,297,691; 2,907,674; 3,081,263; 3,241,998; 3,189,447 (1,3,4- oxadiazole); 3,1 12,197 (1,3,4-triazole); 3,097,095 (imidazoline); 3,180,729 (pyrazoline); 3,037,861 (polyvinyl carbazole); 3,180,730 (triphenylamine); 3,162,532 (aromatic vinyl polymers), and the like. It is to be specifically noted that the organic photoconductors with which the present invention find particular application are not especially limited, but can be freely chosen from appropriate organic photoconductors as are known in the art.
• One especially preferred organic photoconductor is poly-N-vinyl carbazole, preferably having a molecular weight of from about 5,000 to about 500,000.
• EXAMPLE 1 A solution prepared by dissolving g of poly-N- vinyl-carbazole having a molecular weight of 300,000 and 50 mg of the dye prepared in Synthesis 1 in 200 ml of methylene chloride was coated in a dry thickness of about 10 microns on a paper which had been subjected to a conductive treatment (polyvinyl benzyl trimethyl ammonium chloride was coated in an amount of 2-4 g/m on the paper).
• the photosensitive material thus obtained was statically charged in the dark by an ordinary electrophotographic process (corona discharge) and then image- 'wise exposed to white light in an exposure amount of 31 lux-second.
• an electrophotograhic developer or a toner prepared by adsorbing a 5:5 weight parts kneaded mixture of carbon black and polystyrene on glass beads 0.5 mm in diameter a sharp image was reproduced.
• the results of testing the relationship of the proper exposure amount and the amount of the sensitizer are shown in the following table.
• EXAMPLE 2 The dye obtained in Synthesis II was added to 20g 'of poly-N-vinylcarbazole and the sensitization-effect rosin modified phenol-formaldehyde resin, 55 parts by weight;- boiled linseed oil, 13 parts by weight.
• R represents a hydrogen atom; an alkyl group having 1-5 carbon atoms; an alkyl group substituted by a halogen atom, a hydroxyl group, or a cyano group; or an acyl group substituted by a halogen atom, a hydroxyl group, or a cyano group;
• R represents CH where n is a positive integer of 2 to 6 or CHZQCHZ R represents a hydrogen atom, a halogen atom, a nitro group, an alkyl group, OR, or -COOR', wherein R is an alkyl group having l-5 carbon atoms; and X repi a R (R llut a.
• X is Cl, Br, I, BF4, C10 or 3.
• the sensitizer as claimed in claim 1 wherein said acyl group is selected from those of the formula i l I R CO, where R, is a C alkyl group, benzyl or toluyl.
• the electrophotographic photosensitive material as set forth in claim 5 in which the amount of the dimerized cyanine dye is from about 0.01 to about 10% by weight of the organic photoconductor.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Indole Compounds (AREA)
• Photoreceptors In Electrophotography (AREA)

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Citations (2)

• 1972
  • 1972-05-31 JP JP5449672A patent/JPS5531463B2/ja not_active Expired
• 1973
  • 1973-05-29 US US364263A patent/US3874943A/en not_active Expired - Lifetime
  • 1973-05-30 FR FR7319654A patent/FR2186678B1/fr not_active Expired
  • 1973-05-31 GB GB2612773A patent/GB1406766A/en not_active Expired
  • 1973-06-01 DE DE2328028A patent/DE2328028A1/de active Pending

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