DE2361336A1 - ELECTROPHOTOGRAPHIC COPY MATERIAL FOR THE TAKING OF X-RAY IMAGES - Google Patents

Description

K ²²⁸⁰ FP-Dr.N.-ih November 27, 1973

Description for the registration of the KALLE AKTIENGESELLSCHAFT Wiesbaden-Biebrich for a patent

Electrophotographic copying material for recording

of X-ray images

The invention relates to an electrophotographic copying material for the recording of X-ray images, which consists of a carrier made of a transparent plastic film, a conductive intermediate layer, a transparent one Photoconductor layer and at least one * X-ray intensifier layer consists.

X-ray electrophotographic recording materials are known. They usually contain as photoconductors. Elements with a higher atomic number or their compounds, since only such photoconductors have sufficient absorption capacity for X-rays. Such materials

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are e.g. in the German Offenlegungsschriften I 954 634, 1 956 668 and 2 055 773. It is also known, for example from DT-OS 1 905 329, the recording material add phosphors to increase the sensitivity. It is also known in this context by X-ray excitable fluorescence1 fluorescent substances use that are also photoconductors (DT-OS 1 622 346),

All of these known X-ray electrophotographic Materials have the property that they are not transparent to visible light or that this light is strong to sprinkle.

They are also electrophotographic ones that are sensitive to visible light Copy materials based on organic Photoconductors known in the visible spectral range are transparent or practically transparent (DT-OS 1 906 and 2 015 257). However, these materials are for recording not suitable for X-rays, since the atoms contained in the known organic photoconductors due to their low atomic number have only a low absorption capacity for X-rays.

On the other hand, the consumer and user of X-ray material, i.e. the radiologist or materials tester, when evaluating the recordings of the predominantly used halogen silver materials on the use

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more transparent materials set in transmitted light to be viewed as. It would therefore be highly desirable to have an X-ray electrophotographic material that which has a transparency comparable to that of silver film at the background areas.

The object of the invention was to propose an electrophotographic copy material for recording X-ray images, with which one obtains pictures, their background points are transparent in the visible spectral range.

The invention is based on an electrophotographic Copy material for the recording, from Röntgenbi 1 dem, the a transparent support, a conductive intermediate layer, a photoconductor layer and at least one X-ray intensifier layer contains.

The copying material according to the invention is characterized in that that the conductive intermediate layer is optically homogeneous and has a surface resistance of less than 10 ohms, that the photoconductor layer is optically homogeneous and contains an organic photoconductor, preferably the Combination of carrier, conductive intermediate layer and

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Photoconductor layer has a transparency in the visible spectral range of at least 50 % , and that the X-ray intensifier layer bzvi. the X-ray intensifying layers are in the form of foils which can be separated from the combination of carrier, conductive intermediate layer and photoconductor layer.

The copying material according to the invention preferably has a separable layer on each side of the combination of carrier, conductive intermediate layer and photoconductor layer X-ray intensifier layer.

The separable x-ray intensifier layers can either designed as self-supporting foils or suitable Carrier films can be applied, which do not necessarily have to be transparent to visible light.

According to the invention, a method for producing transparent X-ray recordings by electrophotographic means is proposed, which consists in electrostatically charging an electrophotographic copying material of the type described above, irradiating it image-wise with X-rays, separating the X-ray intensifying layer or the X-ray intensifying layers from the remaining material ¹ and the Developed and optionally fixed charge image contained on the exposed photoconductor layer.

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The material and method according to the invention allow transparent x-ray images on electrophotographic Paths without complex transmission methods and devices by direct irradiation and developing a recording material.

The multilayer material can consist of a cohesive There are structures in which the X-ray intensifying films are solid but separable 'adhere to the transparent support and / or the photoconductor layer. It can also come from a loose superimposed combination of X-ray intensifying foils and photoconductive material made of transparent support, conductive layer and photoconductor layer exist, the are only placed on top of each other immediately before exposure. The X-ray intensifying foils can therefore be reused be. They can contain fluorescent or non-fluorescent pigments as reinforcing substances fluorescent pigments are preferred. Appropriate the fluorescent luminescent pigments are chosen so that their emission spectrum is based on the absorption spectrum of the photoconductor used is matched. Suitable fluorescent and non-fluorescent enhancers are customary in the trade. As the organic photoconductor layer itself practically does not absorb any X-rays, it is particularly advantageous to each have an X-ray intensifier film

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the front and back of the ph-oto.lei tfä'hi gen combination to be placed in a sandwich arrangement, reducing the sensitivity of the material compared to X-rays is increased considerably

As transparent carrier materials for the intermediate and Photoconductor layers are used in a known manner, colorless, transparent plastic films. Foils, for example, are suitable from cellulose esters, e.g., cellulose acetate; Polycarbonates, Polyimides, polystyrenes, polyesters and polyolefins. Polyester films, especially those made from polyethylene terephthalate are preferred because they are commercially available in a suitable quality.

A surface of the carrier film is connected to an electrical conductive coating. This can be done, for example, by vapor deposition suitable metal oxides, such as tin dioxide or indium oxide, or by applying a thin layer of a conductive one Polymers made. Examples of suitable conductive interlayers are printed in the Dutch Patent applications 7 007 058, 7 007 059, 7 007 060, 7 007 and 7 007 062, the German Auslegeschrift 1 522 635 or the German Offenlegungsschrift I 906 969 described.

The conductive layer is said to have a surface resistance

1Π 8

of less than 10 ohms, preferably of less than 10 ohms. Surface conductivity is measured by placing electrodes on opposite sides of a square patch of any side . The measuring procedure is in the VDE regulation 0303,

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Part 3, and described in ASTM regulation D-257-61.

The conductive intermediate layer must be optically homogeneous and have sufficient transparency so that the. Total transparency of the bi-supporting material, as stated above, greater than 50% _; is preferably greater than 7G % .

In order to improve the adhesion of the intermediate layer, the surface of the film can be in a suitable manner, for example. Trichloroacetic acid solution , be pretreated. .

On the conductive intermediate layer is the transparent photoconductor layer. This can either be colorless, or, due to the sensitization, be slightly tinted. The tint may only be so strong that the finished, toned and fixed image can be viewed through it is not affected ". In any case, this layer must be optically homogeneous, i.e. it must have the same refractive index at every point. ■ ■ V -

Suitable organic photoconductors are derivatives of certain: especially five-membered heterocycles, e.g. from Drazolen, Triazoles, oxazoles, oxdiazoles, thiazoles or thiadiazoles, in which the heterocyclic ring is substituted and or or carries fused aromatic rings, which optionally themselves carry substituents. Examples of such photoconductors

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are in German patents 1 058 836, 1- 060 260, 1 120 875 and 1 137 625. Other suitable Photoconductors are polyvinyl carbazole and its complexes with suitable electron acceptors (DT-PS 1 068 115 and T 111 935) and complexes of electron acceptors and formaldehyde condensate! on products of polynuclear aromatics (DT-OS 2 137 288 and 2 228 446). ' The latter types. of photoconductor complexes, especially those made from halo aromatics Formaldehyde condensates and acceptors are used because of them good transparency and high light sensitivity especially preferred. The light sensitivity of the layer to the fluorescence emission spectra can be determined by a suitable choice of the acceptor substance match the luminous pigment used.

As polynuclear »carbocyclic aromatics, pyrene and its substitution products or derivatives of perylene in question, which are polycondensed on their own or in a mixture together with formaldehyde or paraformaldehyde. From these aromatics the ones derived from pyrene are derived Halogen derivatives because of their good solubility properties and their relatively higher electrophotographic sensitivity as expressed in the polycondensate proved particularly suitable. Suitable activators are, for example: Mono-, "Di-, Tri- and Tetranitrof1uorenon, 9-dicyanomethylene fluorene, 9-dicyanomethylene mono-, ö-DicyanomethyUn-di-, and 9-Di cyanomethylen -tri η i trof 1 uoren

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Bi-ndemi ttel can also be added to the photoconductor layers be. "For-the preferred complex photoconductors will be e.g. polyester made from terephthalic and / or isophthalic acid and certain. -Diols preferred. Otherwise are natural and synthetic resins and polymers as indicated in DT-PS 1,058,836, column 3, lines 15-38 ',. " suitable as a binder.

As further additions, the photo layers can be placed under other plasticizers, e.g. di butyl phthalate, wetting agents, e.g. silicone oils, and dyes "contain in such quantities, in which they do not make the transparency of the layer too strong. reduce.

The copying material according to the invention is used in the usual manner processed. That with at least one, preferably two X-ray intensifying foils covered electrophotographic Material is charged evenly and pictorially with it X-rays irradiated. By combining the front and back intensifying screen .ffirt "a transparent, You can use high-light tips with a photo layer get by with particularly low radiation doses, which is particularly advantageous in medical diagnostics. Then the. Intensifying screens removed, and the charge image is developed by concreting and, if necessary, fixed.

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- το -

Although the material and method according to the invention are preferably provided for recording X-rays, it is of course also possible to record other high-energy radiation such as corpuscular, electron or $ * radiation in the same way when using suitable reinforcing substances.

The following examples illustrate preferred embodiments of the .Kopiermateri al.s and method according to the invention. Quantities and percentages are, if nothing else given is to be understood in weight units.

Example 1 :

A solution of 2 g of bromopyrene resin, prepared according to Example 4 of German Offenlegungsschrift 2 137 288, 1 g of one Polyesters made from aromatic dicarboxylic acids and aliphatic Diols (PE 200 from Goodyear) and 0.3 g of dicyanomethylene-2,7-dinitro-fuels in 25 ml of tetrahydrofuran, is applied to the using Surface of a 50 .mu.m thick biaxially stretched polyethylene terephthalate film made conductive by vapor-deposited tin dioxide painted on. After drying, a well-transparent recording material with a slightly greenish tint is obtained. the maximum sensitivity of the photoconductor layer is in Wavelength range from 600 to 650 nm.

For the production of X-ray images, the above is described Recording material charged in the usual way by corona treatment and packed between two fluorescent light screens that

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-τι- '

a fluorescent red luminescent pigment of the composition Y _? O ~: Eu included. The emission maximum of the light emitted by this pigment is 610 nm. After the image-wise irradiation of the material with soft X-rays, the fluorescence intensifier films are removed and the 'latent; The charge image on the photoconductor layer is made visible by concreting with the toner described in German Patent 1,188,440, Example 2. The toner is fixed on the photoconductor layer by briefly heating it to 130-140 ° C , can be viewed in the review ..:.; '

Similar results are obtained when looking at the following Table specified acceptor substances with the same photoconductor resin combined.

Table :

1 fd. No. Acceptor substance -: color of the complex

1 . ν 2-nitro-fluorenone yellow

2 2,7-dinitro-fluorenone orange

3 2,4,7-Tri ni tro-f Tuorenon red-brown.

4 2, 4,5,7-tetranitro-f1üörenon green - ϊ

5 9-dicyanomethylene fuels light red;

6 S-dicyanomethylene-Z-ni tro- .. - red-brown

f1uoren;

7 9-dicyanomethylene-2,4,7- green

, tri ni tro-f 1 uoren ■ -; ;: _r

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Example, 2:.

_{On a 50 /} um made superficially conductive by polyvinylbenzyltrimethylammonium chloride according to DT-AS 1-522 635

thick polyester film as in example 1 becomes a coating solution applied in the following composition:

62.5 % ethylene glycol monomethyl ether, 15.5 % butyl acetate,
13.5 % butanone,

5 % 2,4-bis (4-diethylaminophenyl) -1, 3,4-oxdiazole and 3.5% of a maleic anhydride-styrene copolymer with an acid number of 180 and an average molecular weight of about 20,000.

Sensitization is achieved by adding the following substances achieved: basic shrine blue (CI. 51004) 1: 750, Acridine orange (CI. 46005) 1: 2250 and rhodamine FB (CI. 45170) 1: 1000,

in each case based on the amount by weight of Oxdiazo! derivative. The batch also contained 0.1% by volume of silicone oil (paint aid Dow Corning No. 6). After drying, the result is a colorless, clear, transparent recording material of im visible spectral range almost panchromatic sensitivity. Fluorescence intensifier films are used which have a yellow-green emitting luminous pigment of the composition (Zn, Cd) S: Ag contain, the emission maximum of which is 530 nm. After concreting and fixing as in Example 1, the result is X-rays that can be viewed easily,

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Example 3:

A transparent layer with a pale brownish tone manufactured as follows: ■ ■

2 g of 3-bromo-pyrene resin are mixed with 0.5 g of trinitro-tuoranthene activated and used together with that in Example 1 Polyester processed into a layer in the usual way. The trinitrofluoranthene is produced as follows:

.20 g of finely ground fluoranthene are dissolved in 200 ml of nitric acid, (d = 1, 4) refluxed for 7 hours. After that, will the precipitate filtered off, first with glacial acetic acid and then washed acid-free with water. There is no cleaning necessary. Yield 2 4g (70% of theory). Melting point 305 ° C (not corrected). Analysis: N calc .: 12.45%, N found: Ϊ2.4%,

A slightly reddish layer can be achieved by activating the same amount of bromopyrene resin with 0.2 g of tetranitroperylene while maintaining the remaining components can be obtained. The tetranitroperylene is obtained as follows: .- ■

60 g of powdered perylene are dissolved in 4.2 l of nitric acid entered with a density of 1.4 and refluxed for 1 hour cooked. After cooling, the precipitated tetranitroperyl is s sucked off, first with nitric acid of the same density and then washed acid-free with water. Another cleaning

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is not necessary. Yield: 70 g (70 % of theory).

Melting point over 360 ° C.

Analysis: N calc .: 12.95 %, N found: 12.7 %,

A layer that is particularly sensitive in the long-wave range of the spectrum and has a very slight green color can be achieved by using 9-dicyanomethylene-2,4,7-trinitro fluorene can be obtained as an acceptor, which is particularly suitable for a red-emitting intensifying screen. The layer is made from the following solution:

2 g of 3-bromo-pyrene resin,

0.1 g of 9-dicyanomethylene-2,4,7-trinitro-fluorene, 1 g polyester and

0.3 g chlorinated mixture of di- and terphenyl

(see DT-OS 1 906 969)

are dissolved in 25 ml of tetrahydrofuran and processed as in Example 1 to form a transparent layer.

The obtained electrophotographic materials are charged in the same way as in Example 1, irradiated together with X-ray intensifying films, concreted and fixed. It will be excellently recognizable when viewed through Get x-rays.

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Claims (6)

- 15 - '/'; '■ - Patent claims: 1J Electrophotographic copier material for recording X-ray images, which contains a transparent substrate, a conductive intermediate layer, a photoconductor layer and at least one X-ray intensifier layer,. . ' characterized in that the conductive intermediate layer is optically homogeneous and has a surface resistance of ---- '. less than 10 ohms, that the photoconductor layer is optically homogeneous and contains an organic photoconductor and that the X-ray intensifier layer or the X-ray intensifier layers in the form of Films are present which can be separated from the combination of carrier, conductive intermediate layer and photoconductor layer. " 2. Copy material according to claim 1, characterized in that the combination of carrier, conductive intermediate layer and photoconductor layer has a transparency in the visible spectral range of at least 50%. ■ ^; ■ 3. Copy material according to claim ■ -T, characterized in that / -.- ■ - ■■ that there was a separable X-ray intensifier film on each side wearing. . . - " 4. copying material according to claim * 1, characterized in that that it is a complex of an activator as an organic photo-pus and a polymer condensation product of formaldehyde with polynuclear aromatics. · - ■■ 5 0.982 5/0859 5. Copy material according to claim. 1, characterized in that that the conductive intermediate layer has a surface resistance less than 10 ohms. 6. Process for the production of transparent radiographs by electrophotographic means, characterized in that that an electrophotographic material according to claim 1 is electrostatically charged, imagewise with X-rays irradiated, the X-ray intensifying screen resp. the X-ray intensifying screens from the rest of the material separates and that on the exposed photoconductor layer The charge image contained is developed and, if necessary, fixed. 509825/0859