DE2001905A1 - Electrophotographic process - Google Patents

Description

Patentenvrölti \. 0-1 Inn.F ^ r ^ m-nn, ■ "* UU I

.A.tV: ^ ν

S Hfinchen 27, Mähisir. 22nd

Söh / GI. P 78ΰ /? Χ 320

s-iilt Xerox Limited, London / England

Electrophotographic technology

The present invention relates to an electropjiotographi-] Such a method and an electrO-light-sensitive image-constricting element and relates in particular to an electrophotosensitive layer of photoconductive zinc oxide, an electrically insulating resinous binder and a sensitizing substance.

The generation of a positively colored image by "electrophotograph! *." Is an example of the difficulties encountered in image generation. In ₁

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cases - in which υine white electrical photosensitive layer (for example, a non-sensibilioiertes' Δχχϊ) ί ~ oxide and a binder) is used, is not panchromatic diu-sensitive layer. To obtain a color print by electrophotography, a resolved monochromatic positive is therefore required, which is produced from a colored positive image (a resolved monochromatic Iiegative is required if the development is accompanied by so-called solarization). Jk In order to produce such a chromatically resolved positive, a troublesome treatment using a silver halide film must be carried out. On the other hand, the use of a white, non-sensitized, electrosensitive layer to obtain a color print has the advantage that the base surface (the surface to which the toner particles do not adhere) has a v / eisso color. This means that a color print with a high contrast can be obtained. However, a white non-sensitized electrophotographic sensitive layer generally has a lower degree of sensitivity.

"Furthermore, since the zone of photosensitivity is not j η that visible spectrum falls, a special optical system is required. For these reasons, white people are non-sensitized Electrophotosensitive layers are not suitable for producing enlarged prints from smaller originals. Therefore, according to this method, only one contact is generally used:; t ^ printing carried out with a resolved positive.

■ The disadvantages outlined above can be considerable Dimensions by using: an electrophotosensitive one Layer of the type which has a certain extent of a pan-

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chromatic sensitivity can be eliminated. Of the The reason is that "such a layer is quite a ^ has high sensitivity, and in addition it does not longer is required. to distribute a broken-up film. ",. At the time of irradiation, it is sufficient · to · use. A ■ color filter in front of the sensitized layer. Therefore, a color print on the electrophotographic graph of a colored: Positive image .be obtained, - namely, by tripling; -v the process, which is carried out in an electrostatic charge, irradiation with a chromatically resolved image and there is a development. "-.",:

Electrophotographic processes "are broadly divided into two Subdivided into major classes. One class is through the Xerox (registered trademark) process, when carried out, an image transfer takes place so that, a photosensitive layer can be used repeatedly. the other class is represented by the Electrofax process, when this is carried out, the photosensitive layer itself is used as a support for the image in the finished print.

In the case of a procedure which involves an image transmission takes place is the unpictured Area (corresponding to the .s.-strongly exposed point) in the obtained Naturally white printing, provided that white transfer paper is used, regardless of whether the color of the photosensitive layer. In the case of image transmission, however, the image torture becomes unavoidable Way worsened. Especially when you are on a Falls back on fluid development, it is difficult to find a to carry out perfect image transmission,

Ia case of the EleetrofaX ^ failure, in its

no image transfer takes place because the photosensitive Layer is converted to print, there is no deterioration the image quality as a result of a transmission stage. If a pigment-sensitized photosensitive If the layer is used, the photosensitive layer, which is colored by the sensitizing pigment, is then used is irradiated at the non-image bearing areas of the print. Therefore, the highly exposed area is in the one obtained Print discolored or darkened. For this reason, the obtained image is poor in contrast.

If an image is to be reproduced from black lines, for example in an office copier, then this phenomenon does not pose any serious problems, 'unless that one is bothered that the copies are not particularly pleasant to look at. However, if you want color printing with a continuous tint are reproduced, then the picture quality is considerably deteriorated by this phenomenon, so that this phenomenon is extremely undesirable.

To overcome this disadvantage, it has been proposed to remove the sensitizing pigment from the photosensitive layer after development. For example, there is a method for chemically converting the sensitizing pigment into a colorless substance. However, this decolorizing treatment tends to destroy the toner particles deposited on the image. Even if it is possible to coat the area not provided with an image with a white substance, such a method is nevertheless hardly feasible in practice. j

The invention therefore aims to provide an electrophotographic Process by which one prints with

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of a good quality, these prints non- * discolored areas that do not have a picture.

The invention provides an electrophotographic process available, when it is carried out an electrostatic latent image is formed and developed on an electr Zinc oxide, an electrically insulating resinous binder and a sensitizing substance. This method is characterized in that the sensitizing substance used consists of a. Link , ; of the general formula (I) given below:.

CH-CH.

O = T

NO,

CHO

consists, in which.R _{1 stands} for a hydrogen atom, a halogen atom, OR or R (where R is an alkyl group with 1 - 7 carbon atoms), R ₂ and R ^ each independently of one another. represent an alkyl group having 1-7 carbon atoms and R ^. represents either, (-CH ₂ -) _n SO ₅ H or (-CH ₂ -) _n COOH, 'where η. _; is an integer from 1 to 7. The .used senslb.il.isie-. Rende substance may further include a, .The compound of the general s, _vt - "^ formula (II).

ORiQINAL ttoSPECTED

where R ,, Hp, R- * and R. have the definitions given above, R ₁ - and R- each independently represent a V / water atom, NOp, a halogen atom, CN, OR or COOR, and R is an alkyl group of 1-7 carbon atoms, provided that both R. and R ^ are not] hydrogen atoms at the same time. After the electrostatic latent image has been developed on this electrophotosensitive layer, the surface of this photosensitive layer is uniformly irradiated with visible light to remove the color of the photosensitive layer due to the above-mentioned compound.

The present invention also provides an electrophotosensitive An imaging member comprising an electrophotosensitive layer composed of photoconductive dome zinc oxide, an electrically insulating resinous A binding agent and a sensitizing substance. This element is characterized in that the sensitizing substance. from a compound of the general formula (i)

CH-CH

CHO

consists, where R ^ stands for a hydrogen atom, a halogen atom, OR or R (where R is an alkyl group with 1-7 carbon atoms), R2 and R, each independently represent an alkyl group with 1 - 7 carbon atoms and H.

009130/1114

PAGINAL IN ^ ECTjED

represents either (-CH ₂ -) _n SO ~ H or (-GH ₂ -) _n COOH, where η is an integer from 1 - 7, or a compound of the following general formula (II)

indicated above in each case independently of wherein R ₁ , R ₂ ,

have nen definitions, R ₁ - and

each other for a hydrogen atom, NO ₂ , a halogen atom GN / OR or COOK, and R is an alkyl group with 1-7 hollow "st off atoms, provided that both Rc and a'uclV'RA" do not mean hydrogen atoms at the same time . ; -> ·

Some of the spiropyran type compounds are known to be substances showing photochromism. It has been found that "if the spiropyran-type compounds of the above formulas (I) or (II) are adsorbed by a photoconductive substance such as zinc oxide, they are deposited into a chromatic state so that the photoconductive Substance is made photoconductively sensitive to light adsorbed by the coloring material. The color which is assumed by the electrolessensitive layer by means of the sensitizing substance of one of the above-mentioned formulas (I) or (II) can be in a simple manner . by irradiation _:. removed with visible light.

, Λ

i-t'i ■

QRfGlfsJAL

The above-mentioned embodiments and characteristic Points of the present invention can be summarized as follows:

1. The sensitizing substance of the general formulas (I) or (II) is adsorbed by the photoconductive substance such as zinc oxide. As a result of this' treatment the photoconductive substance is sensitized to light with wavelengths that are determined by the sensitizing Substance to be adsorbed.

2. The photoconductive substance used is one which adsorbs visible light as little as possible shows. The photoconductive substance obtained by the treatment according to 1. is suitable with a insulating resin mixed and kneaded, whereupon the resulting mixture in the form of a layer on an electrically conductive Underlay or underlay that has been treated in such a way that it conducts electricity has accepted. In this way, the «electrolight sensitivity» Borrowed imaging element created. j

3. The light-sensitive layer produced in this way is uniformly charged, irradiated with light in image configuration, whereupon the latent image obtained is developed. In the case of multi-color printing, the same process is used with different combinations of resolution filter and 5? One repeated.

4. The sensitive layer, development as under 3., is] irradiated in an intense manner with visible light. The irradiation removes the color that is within the sensitive Layer has been generated by the sensitizing substance represented by the general formula (I) or (II). The consequence

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of which is' that the optical density at the non-image bearing Position is reduced. The finished print therefore has excellent image quality because it is white Background and thus has a high contrast.

The following is a more detailed description of the method of operation according to the invention and of the method according to the invention. materials used. In order to prevent the photoconductive substance from introducing color into the sensitive layer in which it ^; is concentrated, the photoconductive substance should appropriately "absorb as little visible laughs as possible * With regard to" this requirement, photoconductive zinc oxide or photoconductive titanium oxide have proven to be particularly suitable " of the sensitizer depends on the temperature of the surface, the photoconductive substance. If this point of view is also taken into account, then zinc oxide is the most suitable. The reason for this is that zinc oxide is on his; The surface is comparatively basic and therefore adsorbs a sensitizer with an acidic residue in a satisfactory manner, while titanium oxide is acidic on its surface compared to zinc oxide and therefore tends to adsorb a basic sensitizer. according to the invention is the use of zinc oxide as a photoconductive. Substance just a characteristic.

Examples of sensitizing substances which fall under the formulas (I) and (II) given above are - ■> .- ■ - ·. given below. It is to be noted that the invention not · .on \ using the following · .aufge-- ■ - "- ■ led substances is limited .- .- · ■?." ■ · - - ^ ^3v.: : ■ "- ■ · ■:" ·

- · 10 -

Sensitizing substance IJr. 1:

CH,

CH-, - ^ CH - CH

CH ₉

CH ₉

CH ₉ ι * -

CH ₉

ι ^ -

V_ NO,

CaO

Sensitizing substance Mr. 2:

CH

COOH

Sensitizing substance no.3:

CH,

CH,

CH-CH

ν:

. ^ ₂

/ CHO

COOII

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Sensitizing Substance No. 4; • ίο

.0H

(CHo)

■ 2'4

Sensitizing substance no ", 5:

SO, H

Sensitizing substance Mr. 6:

(CH ₂ ) ₂ GOOH

0 0 9830 / 169A

SensibJ e substance —Λ No. 7: • "fTT
'"I ^H 5 K Λ ) - 2 ^ 2
t dance OH Sensibili. .. de Subs Wr. 8th: ^CH;

NO,

Sensitive

Substance ITr. 9:

^{/ n} 3

-ITO,

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S / -ff «'

ii. -Öfcfrgiääg Hi

* ^m i

Silitliil fei f 11,

i im

% φΐ

Sensitizing substance No. 13 ί
CH,

ÖOOH
Sonic sensitizing substance ilr, 14:

VaQhB sharing a method according Velciier is described ^ the öensibilisierönde substance preceding fOrmelä (ίj barren (II) is added to the photoconductive substance. Üiö serisibiiisiörende substance may be dissolved in a geeigneteri iröötiügsiaittei äiif -werdenί -What the photoconductive Zinko ± yd the erttaltenen solution added so that I have the sensitive

Deposit substance on the photoconductive substaüa Optionally, the photoconductive substance can be one

be venaischt iööli © rSnden resin and knotted ^ Ito tjäüi the sensibiiisierenden the substance dei erhalteüeii Hi is added. ,

Apart from the fact that the 4-way sensitizer ^ roped ^ art »0 v _r he ~ is esr ^ zitäckmäB & xg, ali ^ ^ ehandluiigeÄ to dissolve the sensitizer in the dark.

-BADORtGJNAL

'... ", .- - ■■": ■ - ■■ - "■■ - 15 -; ' .- '■ ■' ■ .- ■ ■.;.

The sensitizing substance will appear on the zinc oxide mixing and kneading the insulating resin with the zinc oxide adsorbed, then the solvent should for the sensitizing substance in an expedient manner also be a good solvent for the resin. This is therefore, because the resin is immediately after adsorption the sensitizing substances are mixed and kneaded can «Is the solvent for the sensi'ixlizing Substance is not a good solvent for the resin, then it is advisable to use the mother liquor after adsorption. the sensitizing substance accrues through a good one To replace the solvent for the resin before "adding the resin"

The sensitizing substances of those given above Formulas (1) or (II) lose their color when visible light is absorbed. The amount of visible Light required for discoloration is far greater than the amount of light that is usually used for irradiation used in electrophotography. Therefore, this irradiation with light in the image configuration does not discolor the light-sensitive layer and does not prevent sensitization. · "'' '

In general, a substance exhibiting photoefiroinism is characterized in that the reversible color change is very rapid. In the case of sensitizing substances falling within the above-mentioned ordinances - (I) and (II), the color becomes After it has been removed once, it is only recovered with considerable "" ^ ch'wie ^ i-glEÖ ^^ 'äf'-The layer must be heated or with ultraviolet rays; b ^ stbsnaf ⁱ wefi ^ en '. * IM Malier ^ a ie' color · in the elelctropliotogräph'iScHen ^ß em§ £ xä '& McfieT ^ SchieKt ta

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the stage of development by irradiation with an intense visible light has been removed, then no new color formation takes place under the usual storage conditions instead of. If the color reappears under unfavorable storage conditions, it can in turn by renewed. Irradiation of the layer with visible light can be removed.

Preferably, the sensitizing substance corresponding to one of the above formulas (i) or (II) is applied to the photoconductive zinc oxide in an amount of 0.1 mg to 100 mg of the former per 10 g of the latter. The application is preferably carried out in an amount of from 1 mg to 20 mg of the sensitizer per 10 g of zinc oxide. The sensitizing substances represented by the general formulas (I) or (II) given above can be used either alone or in combination. ^{! ;}

The insulating resin, which is used as a binder for the erfindungsgeiiiäss The photoconductive substance used is of the type that is used in the usual way for production used by electrophotographic sensitive layers. This resin is not particularly limited. In particular, alkyd resins, styrene / butadiene copolymer resins and silicone resins give favorable results. Additionally For example, polymethacrylic acid ester resins can be used for this purpose and epoxy ester resins can be used.

The binder for the photoconductive substance used in the present invention used, should be such that it does not detrimentally affect the sensitizing Affects substance which corresponds to one of the formulas (I) or (II) given above. Besides, it should

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- · ■■ "■■ - ¹⁷ - ■■ '■;" .. ■'.

not. the removal of the color of the sensitizing sub-:. punch after, prevent development. -It is therefore necessary A suitable binding agent for each of the sensitizing agents used To select substance. .....- ■.

The photoTeitende substance which has adsorbed the sensitizing substance, which corresponds to one of the 'general formulas given above (I) or (ίΐ), is thoroughly-mi _T t. the insulating resin serving as a binder is mixed and kneaded. The obtained mixture becomes

. - in the form of a {Sxchieht on a conductive surface or a document that has been treated in such a way, " that it has assumed a conductivity. It is of course advisable to use a good solvent for the insulating resin to add to facilitate mixing and kneading. The. Produced in this way The electrophotographic sensitive layer is dried and then stored in the dark so that it is adapted to the dark. The electrophoto-

- The graphic sensitive layer decreases as a result of the sensitizing Substance which: -any of the-above

• corresponds to general formulas (I) or (II) and on which zinc oxide is deposited, color on. The electrostatic latent image "is formed on this electrophotographic sensitive layer by an electrophotographic process" _: - ■ ■ - ■ - '■ - ■■ "■. ·

In carrying out a typical such process, the electrostatic latent image becomes; gebil- in the manner of ^"1 '■' ■■ det, - that a uniform loading · ^ ^and: · -ansciilieösende irradiation with a · Mchtbild carried ν · One can j'e'doch ¹ -on any method '-. s back cross, with its · ^Help; the '* * ^{r> r} ·'^·; latent image generated ^r can Die'Entwicklung Täss ^ t si chi.

0P9830 / 1694

carry out according to one of the various known methods, for example according to the cascade method, the magnetic brush method, your liquid method or the powder cloud development method. The liquid process as well as the powder servoXken development process, which are especially suitable for The reproduction of a graduated tint are suitable, are particularly suitable for the development according to the present Invention. After the development, the toner image is fixed. The fixing of the toner image can, for example P done by a Y / heat setting method. As a result of this process, the toner is fixed directly to the substrate is, learner can a uniform painting of the developed Image. The invention is not dependent on the developing and fixing method used .

The removal of the color from the sensitive layer by irradiation with visible light can take place before or after the fixation take place. The sensitive layer is irradiated with visible light in the same way as the layer open to the action of intense light radiation emitted by a suitable light source becomes, v / ob with the irradiation for a short period of time he follows. This is done, for example, by irradiation with sunlight or with light from a tungsten light source.

In general, prints are kept in light trees. Does not need to be removed at once, the color of the photosensitive layer ^itself}, then the object of the invention can be i: achieve a sufficient degree in such a manner that the fixed pressure in a bright room is-left. Light absorbed by the sensitizer can remove its color. Is a

009830/1694

Immediate removal of the ParbB is required, hj this can be done, for example, by irradiating with a "light whose luminosity exceeds 10 OQD Lux" where such light is separated from piner wolfrani light rays, the one has color temperature door of 2800 ⁰ K It is needless to mention that the Bestrahiüng $ dit with increasing ^ more expectant;. Liohtguelle comparable Κν & ψΐ v (erderi kaiiti If the sensitive layer ßonntenlipht ließtrahlti then reiqht example, a Beistrahluhgaaeit from 1 to 5 minutes. for the stated purpose. |

IiieYerf ahrens stuf ene (Sehsibirisierung means of a sensibiliöiereriden SübstahZj which a -der. Above formulas (1) or (Il) corresponds, as well as the removal of]? Ar _t be yon the non-imaged (highly exposed) i? Areas of the light-sensitive layer (by irradiation with siphtable light after the development stage), which characterize the electrophotographic process according to the invention, can also be applied to other electrophotographic processes. For example, the process steps can be applied to an electrophotographic process in which no loading occurs. In addition, an application to an electrolytic electrophotographic process is possible.

The following examples illustrate the invention.

6 mg of the previously sewn sensitizing substance Kr. · T are dissolved in 40 ml of methanol. 5 g of a photoconductive zinc oxide (manufactured by Sakai Chemical) 'are added to the obtained I-ösjung'"before thoroughly stirred"

will, .- ". ■ ..

The dispersion obtained is then centrifuged, a zinc oxide being separated off on which the above mentioned sensitizing substance No. 1 is deposited. The zinc oxide on which the moist sensitizing Substance is located, is then a resin solution added to the following composition:

Styresol 4400 (manufactured by Nippon Reichhold) (as a non-volatile component) 0.6 g

"Desmodule L (manufactured by Bayer)

(as a non-volatile component) 0.4 g

Styresol 4400 is a styrene-containing alkyd resin. It is marketed as a 5.0 # toluene solution. Desmodule 1 is a product obtained by reacting 1 mole of trimethylolpropane with 3 moles of tolylene diisocyanate. It is marketed as 'Ib /' igö ethyl acetate solution. The substances are weighed out in the amounts mentioned above and dissolved in a suitable added amount of butyl acetate. The resin solution obtained and the treated zinc oxide are thoroughly stirred using a ball mill. The ψ obtained dispersion is spread in a dry thickness of 6 u on a paper which has been treated in such a way that it has become electrically conductive. After propagation, the layer is dried and in a luftthermostatoad nit a temperature of 40 ⁰ G during a 24 hour period stored.

All treatments are performed in a dark room carried out. The electrophotosensitive one obtained in this way Layer has a light blue color due to the sensitizing substance No. 1, Die

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reflective optical density is 0.52. "j

'■' ■ ^v I

This light-sensitive layer is uniformly medium ;;
a negative corona discharge of -7000 volts, "
It assumes a surface tension of -5: 2.0 volts,. - 'In this state, the sensitive layer is directly in
Maintained contact with a positive original and through there. _;
Original with light from a tungsten light source, with 1000 Li *
- irradiated for a period of 0.4 seconds ·. Immediately " ¹
The sensitive layer is removed immediately after the irradiation winds, namely ■ by introducing it into a.liquid rope · ..- ^? winder of the following composition:.

Commercially available blue offset ink 1 g. - '; * -: Cyclohexane · ■ 1 liter

After the development, the arch, which is the most sensitive ":
Containing layer in a bath of clean isoparaffin ges · - "., The ground toner particles dm wash After the startup": closing drying the image in such a manner fixing '"is \ sprayed that a commercially available clarifier lacquer - ^l | the paint is thoroughly dried, after which the entire upper-j * surface of the sheet during a period of 5 minutes bestrahlt'wird "sunlight.....

The sunlight sets the color as a result of the ^ sensitisie "j; j

Substance # 1 down. Therefore the refl ective, ορ'φ falls. ■ see density on 0.24 at the places that are no image 't {; "" ί · (corresponding to the highly exposed places). The electro- 'i. light-sensitive layer of this example has a V " ^: ■ '

spectral sensitivity, as shown by FIG. 1 wii; ;

is given. The lines dashed by the oblique lines ^ | J reproduced 'area corresponds to the sensitized' F "

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Example 2

The above-mentioned sensitizing substance No. 2 becomes used in a quantity of 2 mg per 5 g of zinc oxide. in the rest are 'the amounts described in Example 1 and Measures used or observed.

The reflective optical density of the electrophotosensitive layer itself is 0.37. Will the photosensitive Layer irradiated with light from a tungsten light source at 60,000 lux for a period of 4 minutes and then developed, before the electrostatic the latent image is fixed on the sensitive layer, then the reflective optical density drops to 0.20. the electrophotosensitive layer of this example has a spectral sensitivity as a function of the wavelength, as can be seen from FIG. The part shown by the oblique lines corresponds to the sensitized Area.

Example 3

A methanol solution of the above-mentioned sensitizing substance (4) is adsorbed on photoconductive zinc oxide. When absorbed, the sensitizer is red in color. After exposure to visible light the color is removed.

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Claims (1)

Claims Biektrophotographisqhes method, "in its implementation an electrostatic latent image on an electric light. sensitive ^ layer is generated and developed from that a photoconductive zinc oxide, an electrically insulating one resinous binder and a sensitizing substance ' is characterized by the fact that the used serifjibilizing Substance of a compound represented by the following general formula (I) -ν /
I. • -
; CH-CH } .- 'BO ₀ 'Ν.' '
I. egg "γ Rv CIIO . ,, "iür _; a. V / asserstoxfaton, a Haioger.utoir ;, OPi or ^f er / R stands (vrohei Ii is an alky ^ group -with 1 - 7! Foal.L \ rutO- - men is) v ~ ~ &n; ^ ⁿ ü ^ .3 Jewells independently, an alicy ppe ^ - with T -, 7 carbon atoms mean mid R. entv . ^: edei- g ^ SevH osier ^ -eH ₂ -) _n C (j0H, ■ -where- η is an integer vy.öji- T- -7 or from a combination of the following general i? ormel (II) ■ '"' ■ _ * ™ 009830/1694 BAO consists, in which R., R ₂ , R ~ and R, have the definitions given above, Rp- and Rg each independently represent a hydrogen atom, I ¹ TOp, a halogen atom, CN, OR or GOOR, and R an alkyl group with 1 - 7 carbon atoms., provided that both R ^ and Rg are not hydrogen atoms at the same time, and after the development of the electrostatic latent image on this electrophotosensitive layer, the surface of the sensitive layer is uniformly applied with visible light to remove the color of the sensitive layer , which can be attributed to the compound mentioned, is irradiated. 2. The method according to claim 1, characterized in that as a sensitizing compound one of the sensitizing ones Substance No. 1-14 is used according to the description. 3. The method according to claim 1 or 2, characterized in that the compounds used in the layer in an amount from 0.1 to 100 mg of the compound per 10 g of zinc oxide. 4. The method according to claim 3, characterized in that the compound used in the layer in an amount of 1 - 20 mg of the compound is present per 10 g of zinc oxide. 5. Elelriroliciiteupi'indliches imaging element from one electrolight sensitive layer consisting of a photoconductive zinc oxide, an electrically insulating resinous binder and a sensitizing substance, thereby ' characterized that the sensitizing substance consists of a Connection of the following more general. Formula 1) 009830/16 4, · HO where R ₁ - represents a hydrogen atom, a halogen atom, OR or R (where R is an alkyl group with 1 - 7 carbon atoms), Rp and R, each independently of one another, represent an alkyl group with 1 - 7 carbon atoms and R, either (- GH ₂ -) _n SO ^ H or (-G ^ - ^ COOH, where ή is an integer from 1 - 7 or from a compound of the following general formula (II) consists in what , and R. Own definitions, Rc and each of the above independently of one another which represents a hydrogen atom, NOp, a halogen atom, CN, OR or GOOR, and R is an alkyl group with 1-7 carbon atoms, provided that both R ₅ and Rg are not hydrogen atoms at the same time. /. 009830/1694 % ■■: · S ₀ imaging element according to claim 5, characterized in that the sensitizing compound is a substance 1-14, as indicated in the description. 7. Imaging element according to claim 5 or 6, characterized in that the compound in the layer in in an amount of 0.1 to 100 mg of the compound per 10 g of zinc oxide. ^r 8. Biiderzeugungselement according to claim 7, characterized in · that the compound in the layer in an amount of 1 - .20 mg of the compound per 10 g zinc oxide is present. 008830/1694 BAÖ ORIGINAL