Abstract: An electrophotographic photoreceptor comprising a conductive substrate having provided thereon a photosensitive layer, wherein said photosensitive layer contains, as charge transporting material (i) at least one triarylamine compound represented by formula (I) ##STR1## wherein the definition of Ar.sub.1, Ar.sub.2 are described in the present specification; and (ii) at least one benzidine compound represented by formula (II) ##STR2## wherein the definition of R.sub.1, R.sub.1 ', R.sub.2, R.sub.2 ', R.sub.3, R.sub.3 ', m and n is described in the specification. The photoreceptor maintains its electrical characteristics stably on repeated use.

Abstract: A novel dichlorotin phthalocyanine crystal having distinct diffraction peaks at 8.5.degree., 11.2.degree., 14.5.degree., and 27.2.degree. of the Bragg angles (2.theta..+-.0.2) in the X-ray diffraction spectrum; a process for producing the dichlorotin phthalocyanine crystal, comprising mechanically grinding a known dichlorotin phthalocyanine crystal together with an inorganic salt, followed by, if desired, a solvent treatment; an electrophotographic photoreceptor containing, in the photosensitive layer thereof, the dichlorotin phthalocyanine crystal; and a coating composition for producing an electrophotographic photoreceptor, comprising the dichlorotin phthalocyanine crystal, a binder resin, and an acetic ester solvent. The photoreceptor exhibits high sensitivity and excellent durability. The coating composition maintains the dichlorotin phthalocyanine crystal in its desired form either while being prepared or after being coated.

Abstract: An electrophotographic photoreceptor comprising a conductive substrate having formed thereon a photosensitive layer containing at least a charge generating material, a charge transporting material, and a binder resin, wherein said charge transporting material comprises a benzidine compound and/or a low-molecular weight charge transporting material having a molecular weight of from 200 to 400 and said binder resin mainly comprises a polycarbonate resin comprising a recurring unit represented by formula (I): ##STR1## and having a viscosity-average molecular weight ranging from 50,000 and 100,000, said charge transporting material and said binder resin being at a weight ratio of from 25:75 to 60:40. The photoreceptor exhibits improved abrasion resistance and improved peeling resistance while retaining excellent electrical and image characteristics.

Abstract: A dichlorotin phthalocyanine crystal showing, in the X-ray diffractometry using a CuK.sub..alpha. ray, a peak at a Bragg angle (2.theta..+-.0.2.degree.) of 28.2.degree. with any other peak(s) observed at a Bragg angle(s) between 25.degree. and 30.degree. having an intensity of not more than 30% of that of the peak at 28.2.degree.. The crystal is useful as a photoconductive material having sensitivity in the longer wavelength region. The electrophotographic photoreceptor containing the crystal exhibits high sensitivity and excellent durability.

Abstract: An electrophotographic photoreceptor comprising an electroconductive support having thereon a light-sensitive layer. At least the outermost layer of the light-sensitive layer contains (1) fine grains of at least one of a melamine-formaldehyde condensate and a benzoguanamine-formaldehyde condensate, and, as a binder resin, a polycarbonate resin comprising a constitutive unit represented by formula (II); or (2) fine grains of a benzoguanamine-melamine-formaldehyde condensate having an average grain size of from 0.03 to 4 .mu.m.

Abstract: Crystals of hydroxygallium phthalocyanine, a method of preparing the crystals, a photoconductive material containing the crystals, and an electrophotographic photoreceptor having the material. The photoreceptor has excellent electrophotographic characteristics. The crystals of hydroxygallium phthalocyanine have distinct diffraction peaks at (i) 7.5.degree., 9.9.degree., 12.5.degree., 16.3.degree., 18.6.degree., 25.1.degree. and 28.3.degree., or (ii) 7.7.degree., 16.5.degree., 25.1.degree. and 26.6.degree., or (iii) 7.9.degree., 16.5.degree., 24.4.degree. and 27.6.degree., or (iv) 7.0.degree., 7.5.degree., 10.5.degree., 11.7.degree., 12.7.degree., 17.3.degree., 18.1.degree., 24.5.degree., 26.2.degree. and 27.1.degree., or (v) 6.8.degree., 12.8.degree., 15.8.degree. and 26.0.degree. or (vi) 7.4.degree., 9.9.degree., 25.0.degree., 26.0.degree., and 28.2.degree. of the Bragg angle (2.theta..+-.0.2) in the X-ray diffraction spectrum.

Abstract: An electrophotographic photoreceptor comprising a conductive substrate having formed thereon a photosensitive layer containing, as binder resins, (A) a polycarbonate resin comprising a recurring unit represented by formula (I): ##STR1## and (B) a polycarbonate resin comprising a recurring unit represented by formula (II) or (III): ##STR2## wherein X.sub.1 and X.sub.2 each represent a hydrogen atom or an alkyl group, or (B') a copolycarbonate resin comprising a recurring unit represented by formula (II) and a recurring unit represented by formula (IV): ##STR3## said polycarbonate resin (B) or copolycarbonate resin (B') having a lower molecular weight than that of said polycarbonate resin (A). The photoreceptor had high film strength against abrasion and causes no toner filming or adhesion of any other foreign substances and is therefore excellent in electric characteristics and image characteristics.

Abstract: Crystals of chlorogallium phthalocyanine, having distinct diffraction peaks at (i) 7.4.degree., 16.6.degree., 25.5.degree. and 28.3.degree., (ii) 6.8.degree., 17.3.degree., 23.6.degree. and 26.9.degree., or (iii) 8.7.degree. to 9.2.degree., 17.6.degree., 24.0.degree., 27.4.degree. and 28.8.degree. of the Bragg angle (2.theta..+-.0.2) to a CuK.alpha. characteristic X-ray; a photoconductive material for electrophotographic photoreceptor comprising the chlorogallium phthalocyanine; and an electrophotographic photoreceptor comprising an electroconductive support having thereon a light-sensitive layer containing at least one or more of chlorogallium phthalocyanine crystals. The electrophotographic photoreceptor has excellent sensitivity and durability.

Abstract: A novel dichlorotin phthalocyanine crystal having distinct diffraction peaks at 8.5.degree., 11.2.degree., 14.5.degree., and 27.2.degree. of the Bragg angles (2.theta..+-.0.2) in the X-ray diffraction spectrum; process for producing the dichlorotin phthalocyanine crystal, comprising mechanically grinding a known dichlorotin phthalocyanine crystal together with an inorganic salt, followed by, if desired, a solvent treatment; an electrophotographic photoreceptor containing, in the photosensitive layer thereof, the dichlorotin phthalocyanine crystal; and a coating composition for producing an electrophotographic photoreceptor, comprising the dichlorotin phthalocyanine crystal, a binder resin, and an acetic ester solvent. The photoreceptor exhibits high sensitivity and excellent durability. The coating composition maintains the dichlorotin phthalocyanine crystal in its desired form either while being prepared or after being coated.

Abstract: A dichlorotin phthalocyanine crystal showing, in the X-ray diffractometry using a CuK.sub..alpha. ray, a peak at a Bragg angle (2.theta..+-.0.2.degree.) of 28.2.degree. with any other peak(s) observed at a Bragg angle(s) between 25.degree. and 30.degree. having an intensity of not more than 30% of that of the peak at 28.2.degree.. The crystal is useful as a photoconductive material having sensitivity in the longer wavelength region. The electrophotographic photoreceptor containing the crystal exhibits high sensitivity and excellent durability.

Abstract: Crystals of hydroxygallium phthalocyanine, a method of preparing the crystals, a photoconductive material containing the crystals, and an electrophotographic photoreceptor having the material. The photoreceptor has excellent electrophotographic characteristics. The crystals of hydroxygallium phthalocyanine have distinct diffraction peaks at (i) 7.5.degree., 9.9.degree., 12.5.degree., 16.3.degree., 18.6.degree., 25.1.degree. and 28.3.degree., or (ii) 7.7.degree., 16.5.degree., 25.1.degree. and 26.6.degree., or (iii) 7.9.degree., 16.5.degree., 24.4.degree. and 27.6.degree., or (iv) 7.0.degree., 7.5.degree., 10.5.degree., 11.7.degree., 12.7.degree., 17.3.degree., 8.1.degree., 24.5.degree., 26.2.degree. and 27.1.degree., or (v) 6.8.degree., 12.8.degree., 15.8.degree. and 26.0.degree. or (vi) 7.4.degree., 9.9.degree., 25.0.degree., 26.0.degree., and 28.2.degree. of the Bragg angle (2.theta..+-.0.2) in the X-ray diffraction spectrum.

Abstract: Dichlorotin phthalocyanine crystals having distinct diffraction peaks at (i) 8.7.degree., 9.9.degree., 10.9.degree., 13.1.degree., 15.2.degree., 16.3.degree., 17.4.degree., 21.9.degree. and 25.5.degree., or (ii) 9.2.degree., 12.2.degree., 13.4.degree., 14.6.degree., 17.0.degree. and 25.3.degree. of the Bragg angle (2.theta..+-.0.2) to a CuK.alpha. characteristic X-ray; a method of preparing dichlorotin phthalocyanine crystals having the strongest diffraction peak at 28.2.degree. in the range of from 25.degree. to 30.degree. of the Bragg angle (2.theta..+-.0.2) in an X-ray diffraction spectrum; and an electrophotographic photoreceptor comprising an electroconductive support having thereon a light-sensitive layer containing the dichlorotin phthalocyanine crystals having distinct diffraction peaks at the particular angles or the dichlorotin phthalocyanine crystals prepared by the method.

Abstract: An electrophotographic photoreceptor is disclosed, which comprises an electrically conductive substrate having thereon a charge generating layer and a charge transporting layer, said charge generating layer containing a resin binder and a charge generating material (selenium or an alloy of selenium), and said resin binder being a polyvinyl acetal resin and preferably a partially acetallized polyvinyl butyral resin. The electrophotographic photoreceptor according to the present invention has a photosensitivity which is less dependent on surface voltage.

Abstract: An electrophotographic photoreceptor excellent in durability is disclosed, which has a conductive substrate having provided thereon a photosensitive layer, wherein said photosensitive layer contains a copolymerized polycarbonate resin comprising repeating units represented by structural formula (I) and repeating units represented by structural formula (II) as a binder resin: ##STR1## wherein m/(n+m) is from 0.1 to 0.9 by molar ratio.

Abstract: An electrophotographic photoreceptor comprising an electrically conductive substrate having thereon a photosensitive layer is disclosed, wherein the photosensitive layer contains, as a charge generating material, a dispersion of selenium or a selenium alloy and at least one squarylium compound represented by formula (I): ##STR1## wherein A represents a fluorine atom, a hydrogen atom or a hydroxyl group, with B representing a hydroxyl group; or A represents a hydrogen atom or a fluorine atom, with B representing a methyl group, in the same binder resin. The electrophotographic photoreceptor not only has broad spectral sensitivity from the visible to infrared region but is excellent in other electrophotographic properties.

Abstract: An electrophotographic photoreceptor is disclosed, which comprises an electrically conductive substrate having thereon a photosensitive layer comprising a resin binder in which the following two kinds of charge generating materials are dispersed: (i) selenium or an alloy of selenium and (ii) a phthalocyanine derivative represented by the formula: ##STR1## wherein M represents AlCl, Mg, VO, InCl or H.sub.2. The electrophotographic photoreceptor exhibits a broad spectral sensitivity extending from the visible to the infrared regions of the spectrum and, therefore, can be suited for printers which utilize such light sources as semiconductor lasers, light emitting diodes, etc.

Abstract: An electrophotographic photoreceptor is disclosed, comprising a light-sensitive layer on an electrically conductive substrate, wherein the light-sensitive layer comprises particles of selenium or a selenium alloy as the charge generating material, and at least one compound represented by formula (I), ##STR1## wherein R.sub.1 represents a hydrogen atom, an alkyl group or an alkoxyl group; R.sub.2 and R.sub.3, which may be the same or different, represent each a hydrogen atom, an alkyl group, an alkoxyl group, a halogen atom, an alkoxycarbonyl group or a substituted amino group; and at least one compound represented by formula (II), ##STR2## wherein R.sub.4, R.sub.5 and R.sub.6, which may be the same or different, represent each a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group or a substituted amino group, as the charge transporting materials.