DE1290428B - Photoconductive layer with an organic photoconductor - Google Patents

Description

The invention relates to a photoconductive layer with an organic photoconductor, optionally a sensitizer and optionally a binder.

It is known that imidazoles, pyrazolines, imidazolones, Furans or triazoles can be used as organic photoconductors.

The disadvantage of this is that the photoconductors have a distinctive color, mostly yellow.

It is also known to use organic photoconductors, for example anthracene, for photoconductive layers and related aromatic compounds with condensed rings.

The disadvantage of these layers is that their sensitivity to light is too low.

The object of the invention is to provide a photoconductive layer which can be used both in the case of a wave

length from 3500 to 4200A a low dark conductivity as well as in the visible range of the spectrum when using sensitizing dyes, high sensitivity, i. H. a big Ability to become conductive even in low light, has and both for manufacturing of planographic printing forms as well as for use in table-top copiers. The invention relates to a photoconductive layer with an organic one Photoconductor, optionally a sensitizer and optionally a binder and is thereby characterized in that they are Ν, Ν, Ν ', Ν'-tetrabenzyl-p-phenylenediamine or a photoconductor contains a derivative thereof substituted on the phenyl groups. The formula for Ν, Ν, Ν ', Ν'-tetrabenzylp-phenylenediamine reads:

^H / =

Ν, Ν, Ν ', Ν' - tetrabenzyl - ρ - phenylenediamine the most preferred because of its ease of manufacture and excellent properties Photoconductor. Other photoconductors are in the p-position of the benzyl radicals through methyl groups or substituted by halogen. The benzyl radicals are preferably only substituted once. Of the Phenylene ring is not substituted as substitution would reduce photoconductivity because of steric hindrance (plane configuration).

The TBPDs can be made by condensing the alkyl halide with paraphenylenediamine will. The alkyl chlorides are preferred. The TBPDe are thus through the reaction of a primary Aryldiamine with an alkyl halide and not by reaction of a secondary diarylamine with an aryl halide. The latter response yields, in addition to being difficult and is expensive, vinyl instead of benzyl derivative.

The invention achieves that a photoconductive layer has available which both when illuminated with light with a wavelength between 3500 and 4200 Å a low dark conductivity as well as in the visible region of the spectrum when using sensitizing dyes has a great ability to become conductive even in a low light. the Tetrabenzyl-p-phenylenediamines are white and leave photoconductive layers produced with them can be used for the production of planographic printing forms as well as in table-top copiers. The photoconductive layer holds a charge of 100 to 400 volts for at least 5 minutes.

According to one embodiment of the invention, the photoconductive layer contains 1 part by weight of binder and 0.5 to 0.1 part by weight of tetrabenzylp-phenylenediamine.

The coating liquid contains 4 to 10 parts by weight of solvent. Suitable solvents are benzene, toluene, methyl ethyl ketone, methyl isobutyl ketone, chloroform or methylene chloride. All usual binders are used. The coating solutions are coated on a support and when dried form a solid, transparent solution.

The sensitivity in the visible range of the spectrum is determined in a known manner by sensitizing dyes, such as crystal violet, crypto7yanine, pinacyanol, orthochrome T (C. J. No. ...), rhodamine B or sulforhodamine. Water-soluble quaternary ammonium and oxonium dyes are used preferred.

example 1

76 g benzyl chloride and 10.8 g p-phenylenediamine are mixed in a 500 ml Erlenmeyer glass flask with a solution of 9 g KOH in ethanol. The glass flask is heated on a steam bath, causing a stormy but controllable reaction. When the reaction slows down, a further 27 g of KOH in ethanol and, if necessary, further ethanol are added within 15 minutes in order to keep the reaction under control. The reaction product is ^{obtained in crystallized form after boiling for 3} hours and adding water. The crystals are filtered off and washed thoroughly with water and petroleum ether (30 to 6O ⁰ C). The washed crystals are dried, dissolved in chloroform, shaken with charcoal and filtered through a Celite filter body. The solution is then heated and treated with ethanol to precipitate the compound as white needles (mp 145.5 to 146.0 ⁰ C). Yield 36.3 g, that is 77.6% of theory.

1 part by weight of TBPD, 0.0007 part by weight of rhodamine B base, 3 parts by weight of a polyvinyl butyral and 20 parts by weight of CHCl3 are mixed. This coating solution is applied to a Paper applied. The applied amount is 2.2 kg (dry weight) per ream (500 sheets 63.5 · 96.5 cm). The coated paper is air dried.

The coated paper is charged either positively or negatively under a spray discharge and then imagewise exposed with a 60 watt tungsten lamp. After exposure, red light is used to develop a toner that adheres to the unexposed parts of the image and results in a positive toner image. The toner image is ^{heated to 100 to 130 °} C. for a short time in order to fix it.

RRN ^ N'-tetra ^ -chlorobenzyl-p-phenylenediamine (M.p. 141.5 to 143 ° C) and N, N, N ', N'-tetra-2-chlorobenzyl-p-phenylenediamine (M.p. 142 to 145 ° C) are produced in the same way and result in photoconductive ones Layers with equally good properties.

Example 2

A sheet of paper, which has a hydrophilic titanium dioxide, a carboxymethyl-hydroxyethyl cellulose or a melamine-formaldehyde resin layer, is coated with a solution of 1 g TBPD, 2.5 g polyvinyl butyral, 50 mg rhodamine B and 50 ml chloroform. The sheet is dried and provided as in Example 1 with a toner image. The latter is fixed between 140 and 160 ^{° C.} Then it is washed with methanol, ethanol, isopropanol or mixtures thereof, whereby the hydrophilic layer support is exposed on the hydrophobic image parts not covered with toner. The planographic printing form formed in this way can be used in all customary planographic printing processes.

Claims (2)

Patent claims: 1. Photoconductive layer with an organic photoconductor, optionally a sensitizer and optionally a binder, characterized in that they as photoconductors Ν, Ν, Ν ', Ν'-tetrabenzyl-p-phenylenediamine or a derivative thereof substituted on the phenyl groups. 2. Photoconductive layer according to claim 1, characterized in that it is 1 part by weight Binder and 0.5 to 0.1 part by weight of tetrabenzyl-p-phenylenediamine contains.