DE2108939A1 - Photoconductive recording medium and method for image generation - Google Patents

Description

Photo-conductive recording medium and method for Image generation

The invention relates to a photoconductive recording medium and a method of electrophotographic image formation using this recording medium.

In electrophotography, an electrophotographic recording medium is used that is covered with a photoconductive insulating material layer is provided, electrostatically charged evenly on its surface. Then he will come up with a picture pattern activating electromagnetic radiation, for example with light, irradiated, whereby its charge in the irradiated Sections of the area of the föt öle it is derived from the insulating layer that is due and forming an electrostatic latent image of the non-irradiated areas. This latent electrostatic Image can then be obtained by applying finely divided electroscopic drawing particles to the surface of the photoconductive insulation layer to a visible image to be developed.

A photoconductive layer for use in electrophotography For example, a homogeneous layer of vitreous selenium consisting of a single component can be furthermore, a layer with a photoconductor and a

203838 / QÖS2

BATH ORIGINAL

further components can be provided. A multi-part photoconductive layer for electrophotography is known from US Pat. No. 3,121,006, it consists of several binder layers, which are fine distributed particles of a photoconductive and inorganic Compound dispersed in an electrically insulating organic resin binder. Commercially available In the mold, the binder layer contains particles of zinc oxide uniformly dispersed in a resin binder. This layer is applied to a paper backing.

In the case of the known binder plates, as they are also known from the above-mentioned patent, this exists Binder made from a material that contains injected charge carriers generated by the photoconductive particles, can not transport. Therefore, the portions of the layer, i.e. the photoconductive particles, must be in mutual contact be distributed in the layer in order to allow a charge dissipation, as it is for the cyclical use of a recording medium is required. The known uniform dispersion of the photoconductive particles is normally a relatively high volume concentration of the photoconductor of up to 5O> 6 or more is required to achieve a sufficient mutual contact of the photoconductive particles to ensure rapid discharge. However, it has shows that high levels of photoconductors in the synthetic resin binder layers interfere with physical uniformity of the synthetic resin, which significantly worsens the mechanical properties of the binder layer will. Layers with a high proportion of photoconductors are often characterized by a brittle structure with little or no flexibility the end. If, on the other hand, the photoconductor concentration is reduced significantly below approximately 50 percent by volume, this results a slower discharge rate which allows cyclic or repeated imaging at the higher rate difficult or impossible.

BATH ORIGINAL

209838/0962

Another photoconductive one is disclosed in US Pat. No. 3,121,007 Record carrier is known which has a photoconductive middle layer formed from two phases. This contains photoconductive insulating material particles that are in dispersed in a homogeneous, photoconductive matrix of insulating material are. The photoconductor is in the form of a particulate, photoconductive, inorganic and crystalline pigment, the proportion of which is indicated quite generally as 5 to 80 percent by weight. The discharge from exposure to light is said to be through the combination of charge carriers takes place, which are generated on the one hand in the matrix, on the other hand from the fctoconductive, crystalline pigment in the photoconductive insulating matrix injected.

From US Pat. No. 3,037,861 it is known that polyvinylcarbazole has a certain sensitivity to long-wave Has ultraviolet light and that its sensitivity spectrum in the visible range by the addition of sensitizing dyes can be expanded. Other additives such as zinc oxide or titanium dioxide can also be used together with polyvinyl ^ carbazole can be used. The polyvinyl carbazole is used as a photoconductor, regardless of whether additional substances are used are available to enlarge its sensitivity spectrum »

In addition to those described above, special layer structures have also been known which are primarily used for reffex imaging are determined. According to US Pat. No. 3,165,405, a binder structure formed from two layers with zinc oxide can be used for reflective imaging. There are two separate and adjacent ones Photoconductive layers with different sensitivity spectra are provided to a specific imaging sequence to be carried out according to the reflex method. With this arrangement, the properties of several become more photoconductive Used to take advantage of the common benefits of different layers To realize the sensitivity of several layers,

209838/0952

BATHROOM LOCATION.

From the above explanation of the known compound photoconductive layers shows that with a layer structure the photoconductivity when exposed to light through charge transport caused through the photoconductive layer becomes, as is the case, for example, with vitreous selenium (and other homogeneous types of layers). With photoconductive Binder structures containing inactive, electrically insulating resins, such as those described in U.S. Patent 3 121 006 are known, the photoconductivity or the charge transport results from high proportions of the photoconductive Pigment so that the photoconductive particles touch each other. When in a photoconductive matrix dispersed photoconductive particles according to US Pat. No. 3,121,007, photoconductivity occurs by generation of charge carriers in the llatrix and in the photoconductive ones Pigment particles on,

The known arrangements require a certain lifting mechanism the discharge in the photoconductive layer, in general however, have the common disadvantage that the photoconductive layer surface is exposed to environmental influences during image formation is exposed. In cyclic xerography in particular, there are frictional influences, chemical influences, Exposure to heat and multiple exposure to light as a result of cyclical application. These effects have a gradual deterioration in the electrical properties of the photoconductive ones Layer as a result, whereby surface defects and scratches of the recording medium are reproduced in the images will. Furthermore, local areas of permanent conductivity are formed which no longer store any electrostatic charge ' can, in addition, a high dark discharge occurs.

In addition to the problems identified above, it is with these Photoconductive layers require that the photoconductor make up either the entire layer, as is the case with vitreous Selenium is the case, or that preferably a high proportion photoconductive material is present in a binder.

209838/0962

BATH ORIGINAL

210 & 939

Because a photoconductive layer must consist entirely or for the most part of photoconductive material, the physical properties of a drum-shaped or tape-shaped recording medium in particular are further restricted, since, for example, the flexibility and adhesion of the photoconductor to a supporting base, primarily due to the physical properties of the photoconductor are determined, but not by the synthetic resin or the matrix material, which is preferably present in only a small proportion.

Another type of multi-component photosensitive Layer has a layer of photoconductive material covered with a relatively thick layer of plastic and is applied as a layer structure to a supporting base.

Such a configuration of a recording medium is, for example known from U.S. Patent 3,041,166, they consists of one arranged on a layer of vitreous selenium transparent plastic material, this double layer is arranged on a supporting base. The plastic material should have a large penetration depth for charge carriers of the desired polarity. When generating the image, the The free surface of the transparent plastic material is electrostatically charged with a predetermined polarity. then the arrangement is exposed to activating radiation, which generates a hole-slektron pair in the photoconductive layer. The electron moves through the plastic layer and neutralizes a positive charge on its free surface, thereby creating an electrostatic image is created. However, US Pat. No. 3,041,166 does not list any plastics, which enable such a function, the examples given are limited to structures in which a photoconductor is used for the upper class. The French patent specification 1 577 855 is a special purpose, composite photoconductive recording arrangement known,

209030/0962

BATH ORIGINAL

which is particularly suitable for generating reflective images with polarized light. One embodiment has one layer dichromatic, organic photoconductive particles that Are arranged in a certain orientation. This layer is located on a supporting surface and is provided with a layer of polyvinyl carbazole. When charging and Exposure to light that is polarized perpendicular to the orientation of the dichromatic layer is the dichromatic layer Layer and the polyvinyl carbazole layer permeable to this light. When the polarized light on the white background of a document to be copied falls, it is depolarized, reflected through the layer structure and through the dichroic photoconductive material absorbs. At a In another embodiment, the dichromatic photoconductor is dispersed in an oriented arrangement in the polyvinyl carbazole layer.

In view of the special training and the limited application possibilities of the known recording medium easy to see that there is a need for a generally applicable There is a recording medium which has acceptable photoconductive properties and in addition an exceptional one has physical strength and flexibility, so that it can also be used rapidly and cyclically without increasing Deterioration in imaging properties due to wear and tear, chemical influences and photoaging are applied can be.

The object of the invention is to provide a record carrier to create, which has these properties and in particular an effective generation of charge carriers by Light exposure as well as the transport of such charge carriers enables. Furthermore, a method for image generation with such a recording medium is to be created.

A recording medium with a photoconductive insulating material layer is designed according to the invention to achieve this object in such a way that

20933Ö / 09S2

'BAD ORIGINAL

that the photoconductive insulating material layer is a binder layer which is converted into an electrically active organic Matrix material consists of dispersed and non-oriented photoconductive parts, which when exposed to light Formation of defect electrons are stimulated and these into the matrix that accepts them and enables them to be transported. «Inject aterial, and that the proportion of photoconductive Particles 0.1 to 5 percent by volume of the binder layer amounts to.

A recording device according to the invention thus has a light-sensitive layer which consists of non-oriented, photo-conductive particles in an electrically active organic binder or matrix material. The photoconductive particles must be able to generate defect electrons when excited by light and to inject them into the electrically active organic material. As matrix material can be a transparent organic ₉ polymeric "or non-polymeric material can be provided that does not absorb the radiation of each of the applied radiation range but is active in the look, that the injection enables duroh light excitation generated holes from the fotoleltffihigen part away and transported · In In a preferred embodiment of the invention, the photoconductive particles are dispersed in the active matrix material.

The active, organic matrix material should be used for irradiation applied Yellenllngembercleh does not act as a photoconductor. As already stated, by excitation of light in the photoconductive parts hole-electron pairs are generated and in injects the active matrix material that transports them.

An embodiment of a recording medium according to the invention has a supporting base, for example on one conductive material and a binder layer applied to it. The binder layer can, for example, be particles made of trigonalam selenium within a transparent, polymeric

209838/0982 bad original

-β- 2108933

Layer containing the injection tob defect electrons as well which enables them to be transported. The transparent, active «(polymer) Matrix material enables the 'use of the gate part of an extremely low photoconductor proportions, as was previously not possible with known recording media. There can also be certain Matrix materials are used that have a high degree of efficiency with regard to charge carrier injection and its transport * Furthermore, a listing carrier according to the invention repeated cyclically. Such an application is, for example, xerography »in which the usual an imaging cycle consists of charge, optical projection and image development · An imaging process can be designed, for example, so that the free surface of the binder layer is uniformly electrostatic charged and irradiated with image-wise distributed activating radiation, which is absorbed by the photoconductive "" particles and which the matrix material does not absorb, so that defects created by light excitation in the photocellular particles * electrons are injected into the matrix material and transported therein and a latent electrostatic image is created on the free surface.

The invention is described below with the aid of the exemplary embodiment of recording triggers as well as illustrated in the figures whose properties are described · Show it

1 shows a graph of the photosensitivity

depending on the electric field for an active material alone and in connection with a photoconductor,

FIG. 2 shows a representation similar to FIG. 1 for a second active one Material,

Fig. 3 is a graph of the absorption spectrum of Polyvinyl carbazole,

Flg. 4 a gray representation of the absorption spectrum of the pyran,

5 shows the sensitivity spectra of three photoconductive devices

Fabrics,

BATH ORIGINAL

209838/0952

6 shows the absorption spectrum of the perylene,

Flg. 7 shows an exemplary embodiment of a recording medium according to the invention,

Flg. 8 is a graph showing the discharge property

a record carrier according to the invention with positive and negative coron * ~ charge,

Flg. Ά 9 is a graph "τ Eatladungseigensehaftan another Ausftihruagaforn a erfinrtwgifgemgften recording medium for positive and negative corona charging and *

Flg. 10 shows the properties of a recording medium according to the invention with repeated cyclical use and different irradiation wavelengths.

A photoconductor is a material »which is in a ventilated ZdchtwellenlSngenbereh is electrical light sensing. this means »that its electrical conductivity is due to absorption electromagnetic radiation within a wavelength range oerklleh increases. This definition is necessary because a great number of arceatic, organic Compounds exist »which are known or presumably when exposed to strongly absorbed ultraviolet radiation» X-rays or Gejaaetrade show photoconductivity. The photoconductivity of organic substances is a common one Appearance. Practically rush strongly conjugated organic Compounds show some (trad of photoconductivity when the appropriate conditions are set. Most of these organic substances are primarily sensitive to ultraviolet radiation. However, this will only be commercial marginally exploited »the sensitivity of these substances to short wavelength is for copying or writing documents Not particularly suitable for farreproduction «Since the organic compounds are mainly photoconductive when excited by short-wave radiation, it is necessary that the term "photoconductor * or" photoconductive "only applies to substances that are actually required for an enteprachment

209838/0962

BATH ORIGINAL

in that ¥ e21enlgngenbereleh “own, which is to be applied to your function as a recording medium”.

The active material, which is also referred to as active cathode ray when used as a matrix for a blind face, is a material that is photoconductive, which is an injection of defect electrons generated by lightning or from the photoconductive layer of a minimum of approx · 2 χ 1Cr volts / cm torqued. J ^ amta material also enables the charge carriers to be transported over the air. In addition, it is transparent to radiation of the applied Ythen length range.

Bas active material _# the geaSß the invention on the fcrfco "leltfShlgen Sriäiölit be Place-Name ^ t TZT _t is Insoirsit applied as a leolator sti l ^ selenn @ n" as eiisa © electrostatic charge on F @ 2ilen a S ^ aMiSBgaelmrirkung not derived is "zufiladsEt & l @ lit ait a Geeciartüdlgkeit, which the explanation and ^ wiiel ^ itasg mimts electrostatic view of the latent image prevents · litg cond ^ otst »that the specific · resistance this Haterl & ls iiMisiitst ®m · 10 ¹⁰ Otasssx should be ·

How fivis den ^^ Festandeii Asmfia & nm ^ n emerges the fleleten -fi'i * di @ dcfeiTö Sdhleht of an erf iiktMaggesifien runs-

usable «]! Substances as a tremor too

FntcsleltfSMjgtcelt when they absorb a ray , whose VellenUBge is suitable for electronic excitation

is. Such a termite b®l kssrseß ¥ ellen3Bngen _y which lie outside the spectrum »* for the vesrwandAtesi photoconductor» is insignificant for the function of the iufzelshnisigstrSgere Material for the radiation used is assumed, it came the Lichtaapftadliahkelt des Gers in the .used radiation area is not essential

209838/0962

The reason the active material must be transparent is evident from the fact that in all practical conditions the effectiveness of photoinjection from the photoconductor In the active material as a result of a through the photoconductor absorbed visible radiation the own photosensitivity of the active material in each Yellenlangenbereich is he, visible or invisible, by far surpasses «Dies 1st shown in Figs. 1 and 2, a comparison of the Dependency of the injection sensitivity of the photoconductor Selenium In connection with typical active substances and the own photoconductor of two active substances, polyvinyl carbazole and polyvinyl pyrene from the electric field The curves for polyvinyl carbazole and polyvinyl pyrene in Flg. 1 and 2 received one with samples of 20 microns thick on an aluminum backing made according to the method given in Example 1. The curves for the layer structures of the same Materials with a 0.4 micron thick glassy selenium layer between the active material and the substrate correspond to the structure shown in FIG. 9 and result in the following Method according to Example 3. The curves shown in FIGS. 1 and 2 represent the xerographic gain G as a function of the adjacent field. The xerographic gain is with The following formula is calculated from the initial discharge rate ί

<dv / * t)

Here X is the incident "* · photon flux, 4 the gap in the layer, £ the electrical" dielectricity ccastant and e the electronic "τ **" | _τ El * xerographic gain alters the value gives SlCh ₉ whoever excites one charge carrier per photon and moves it through the layer. It can be seen from FIGS. 1 and 2 that the inherent photoconductivity of the active materials at the wavelength of their peak absorption (ultraviolet excitation) Gewlm results, which are much lower than that of the Kweiphaslgen structure of old photocellular substances

209838/0952 bad ORiGtNAL

1st Bel ictnurctures with thin selenium layers and suitable active materials are gains of approx. 0.7 at a field of approx. 10 volts / cm, with an excitation wavelength in the visible spectrum (4000 to 6000 Angstrom units) being used. It can also be seen from FIGS. 3 and 4 that the above-mentioned active materials show at most a negligible discharge when they are irradiated with a length that is sometimes used in xerography, for example 4000 to 8000 Angstrom units. The improvement in performance possible with a two-phase structure can best be realized if the active material is transparent to the radiation in an area in which the photoconductor is to be used. Any absorption of this desired radiation by the active material prevents the action of this radiation on the photo-capable layer, i.e. at a point where it is to be used. This means that only those active substances should advantageously be used that are in the wavelength range in which the photoconductor has its main sensitivity and is therefore used should be, are permeable.

Amrendungsfälle in a & nen complete transparency in the visible region of the spectrum for the active material is not required, the selective recording schmalbandlger radiations such as, for example, lasers »evaluation vm Spcktraluiustern and possibly color xerography such as the reproduction color coded

Forms.

In the Flg. 3 »4 and 6 is the well-known absorption effect the active substances polyvinylcarbazole * pyrer * and ferylene Fig. 5 shows the xerographic sensitivity spectra for three typical combinations of photoconductor and active matrix, the Fiipfinölichkelt for a combination of amorphous selenium and polyvinylcarbazole is for a 0/4 hikrcn thick layer of amorphous selenium depicted »the ajf one

BAD ORlGfNAL

,,.;,.:, ', 209838/0982

21Q8939

- 13-

ZQ Hikron strong layer of polyvinyl carbazole is arranged. A polyvinyl carbazole binder contains the X-form "metal-free phthalocyanines and trigonal selenium" in a concentration of approx. 3051 (volume fraction phthylocyanine) and approx. The binder structures with the X-shape of metal-free phthalocyanines and trigonal selenium in polyvinyl carbazole are described in more detail elsewhere. Both binder layers have a thickness of approx. 20 microns. As can be seen from FIGS. 3, 4, 5 and 6, certain combinations of active materials and different photoconductors are particularly suitable for the selective use of the sensitivity spectrum.

7 shows a recording medium 10 in the form of a disk, which has a binder layer on a supporting base 11 12 contains »on which an active layer 15 is arranged. The pad 11 preferably consists of one conductive material. Suitable substances are, for example Aluminum, steel, brass, etc., The base can be rigid or flexible and (have any suitable bead, for example it can be used as a flexible tape or sleeve, as a sheet »strip, Plate »cylinder and drum designed to be» Me bearing A backing can consist of several components, for example a thin, conductive one can be placed on a paper backing Layer can be provided, and a thin and conductive layer of aluminum can also be provided on a plastic base or copper iodide can be provided, finally also Ulms can be used with a thin and conductive splint is made of chrome or tin oxide.

Dia binder layer 12 contains photoconductive © Teilehen 30 » which are dispersed in the binder 14 at will and without orientation. The photoconductive particles can be anything suitable inorganic or organic photoconductors and mixtures of such photoconductors exist. To the inorganic Substances include inorganic crystalline compounds and inorganic ones photoconductive © Slasarten »Typiaohe inorganic

2098 3 8/0952

BATH ORIGINAL

- 14 - ■.

Crystalline compounds are Cadmiwunilfoselenld, Csdrnii •• ltiiid _f Cadmium sulfide and mixtures of these substances. Typical inorganic photoconductive egg types are amorphous selenium, and also selenium alloys such as selenium-tellurium and selenium-arsenic. Can selenium in a crystalline Fox "are -Uses, known as trigonal selenium * Typical © organic fotoleitflhige materials are Phthalocyaninpigmentstoffe, such as the X-form aetallfreien phthalocyanines, besehrieben in ά" τ US Patent 3,357,989 "Metallphthalooyanine as Kirpferphthalocyenln , quinacridones "erhitltlieh under the designation Honastral Red, Konastral Violet and Monaetral Red T from DuPont, substituted 2 _# 4-Diaminatrie * ine, besehrieben in US Patentschrijft 3445227" triphenodioxazines, described in is U.S. Patent No. 3,442,731 * Scarlet aromatic quinones, sold by the Allied Chesioal Corporation under the name of Xndofast Double Scarlet _? Indofaet Tiolet Lake B, Indofast Brilliant Scarlet and 2nd @ fast Ormng ». The above-mentioned photoconductors are only examples of more related substances that could be of concern. Do not restrict substances in any way. The work of the photographic part is particularly critical, but the results are particularly good, but particles sit at a risk to whom, e *. O ₉ OI to 1.0 micron «

As already stated, the photoconductive * material is used an inventive recording medium in non-oriented? Arrangement used. This means that the Pigaentstoff or the volatile material with regard to the exciting electromagnetic radiation is isotropic, i.e. it is equally sensitive to every polarization of the stimulating radiation. The active matrix material 14 may contain any suitable transparent organic polymeric or non-polymeric material that allows transport of the injected and generated by X-ray excitation and from the defect electrons emitted by photoconductive pigment permitted »so that they can selectively unload the problem surface. Polymers «it df, f» contain s * n properties Repeatedly appearda lüinlisites of a polynuclear aromatic

i, ' ^: "■ 20983S / 0952" ad original

2108933

Hydrocarbon, which can also contain foreign atoms, for example Nitrogen, oxygen or sulfur. Typical polymers are polyvinyl carbazole (FRP), poly-1 «vinyl pyrene (PYP), Polymethylene pyrene and N-substituted polymeric aeryl acid aides of the Pyrenees. Typical non-polymer substances are carbazoles N-Ethyrearbazole, H-Phenylearbazole, Pyrene, Tetraphene, 1-Acetylpyrene, 2,3-Benzoehrysen, 6,7 ~ Benzopyrene, 1-Broraopyrene, 1-ethylpyrene »1-methylpyrene, perylene, 2-phenylindole, tetracene, Picene, 1,3,6,8-tetraphenylpyrene, chrysene, fluorene, fluorenone, Phenathrene, TriphenylenjV ^ e-Dibeiizanthraoen, 1,2,3,4-Dibenzanthraoen, Benzopyrene, Benzochrysen, Anthraquinone, Dibenzothiophene and naphthalene, besides these substances are also Appropriate coating of active polymeric substances and / or active non-polymeric fabrics can be used

Any suitable polymer (a polymer is a large molecule with repeating small, similar chemical Units) whose repeating unit contains the appropriate aromatic hydrocarbon such as carbazole and the injection of defect electrons and their transport can be used. The one for the active layer The polymers used are not restricted by the invention Polyesters, polysiloxanes, polyamides, polyurethanes, epoxy resins and copolymers in block form, more random Form or compound form (with the aromatic repeating unit) are various examples of the polymers usable as the active material · Further, suitable Mixtures of active polymers with inactive polymers or non-polymeric substances can be used.

The active layer is transparent or generally ni <5ht absorbing in at least a distinct part of the spectrum "between approximately 4000 and 8000 Angströmeiiüieiten, in this" area it allows the InSektioa and transportation of holes which corresponding to a radiation wavelength by the photoconductive pigment particles were generated

209838/0962 BAO original

An upper limit value for the volume concentration of the photoconductor is determined by various factors! 1. Through a stage in which the physical properties of the polymer are severely impaired, 2. through a stage in which there is pronounced transport of the dirt carrier through mutual contact between the particles, and 3. through a stage in which the use of permeable pigment substances such as selenium trigosttalen an excessive scattering of electrons during defect aer charge occurs. The last two factors often lead r repeated cyclical AnwendungsaHgllehkeit au deterioration a ». To achieve inter alia the best combination of physical and electrical properties, the maximum proportion to the photoconductive pigment substance or amr particles do not "ore than approximately be 5 'by volume of the Bindeaittelschicht · A lower limit for the photoconductive particles γοη about 0.1 percent by volume of the binder “Middle layer is required” to ensure that the light absorption coefficient has a value sufficient for the generation of charge carriers. In order to achieve a correspondingly equivalent discharge rate for both types of charging, it is necessary to work with an ice volume filling in which the mean penetration depth of the light is close to the middle of the layer. For the two in FIG. 8 and 9, there is an equivalent discharge in the range of about 1 part by volume of phthalocyanine in 84 parts by volume and about 1 part by volume of trigonal selenium in 190 By volume, it should be noted that these values depend on the respective sohichtatkrke. They also show that even with a positive charge there is a steady increase in the rate of discharge with an increasing proportion of pigment, since the light absorption rate is increased. Even with proportions in the order of 1 percent by volume, the performance is still very high.

BATH ORIGINAL

-.- = ■ - ■ '> 209838/0952

Aue from the above it appears that a critical Air part of the photoconductor »ve» approx. 0.1 to 5 percent by volume » is required to take advantage of the invention kunnes. The preferred range in terms of optimal mechanical properties is between approx. 0.1 and 1.0 Toluene percent feto conductor part "

The thickness of the binder layer is not particularly critical. Layer thicknesses of it. « 2. Here 100 Kikren show TPfrl e nsto ll cmle results, preferably a layer of approx. 5 htm 50 microns is used for particularly good results,

Another embodiment of the arrangement shown in FIG. 7 is provided with a barrier layer with a 4 mm boundary layer between the substrate and the binder layer. The barrier layer prevents the injection of charge carriers from the substrate into the photoconductive layer. Any suitable barrier agent can be used. Typical materials of this type are nylon, oxy resins and aluminum oxide.

The active material can be any suitable polyamide or non-polar material with the required properties, polymeric substances are preferably used because their physical properties, * .B, the fileability, compared to the physical properties of non-polymeric substances are better.

The invention has been described above on the basis of a preferred example of a binder structure However, it can also have other forms. For example, a layer structure can also be used, which is more detailed described elsewhere 1st »An execution forest The visual structure consists, for example, of a support with a photoconductive eye applied to it, on which again a relatively thick layer of an active »organic material is provided. Various modifications to the rail * structure and the binder structure are "grasped" by the basic idea of the present invention,

209838/0952 BADOR ₁ G ₁ NAL

know structural changes of the * layer- structure or the Blndeslttel structure as well as combinations these two recording media usfassaii ·

To demonstrate the improvements possible by the invention over the recording media according to US Pat. No. 3,121,006, the following acts are carried out. Three typical synthetic resin binders of the type described in US Pat. No. 5,121,006 are examined more or less in order to compare the properties of these synthetic resins with the active materials of the present invention. As resins "ground polystyrene, Polyieobutylae-Üiarerylat and a silicone resin, erhültllch 82 SR-General Electric, used under the name · show Testergebaisse that this Barzfcindemittel old connection sit a glassy selenium layer no practical nutsbare T ^ tfw g g yertfri.I ₁ V ^ g possible. Da * Polyiaobutylsiethacrylathars and that Resin bits of a S * Msht structure are tested "meanwhile" a thin bylon "p * rrs" Mcht -ron "κ · 0.1 micron thickness on • iner 10 χ 10 © λ grsiea Alw" iniianmt "r layer from a liquid JJSmmg naoh A 1.0 m thick layer of a 3 "den earxes is then formed on top of the two flats. Up to 0.5 m thick layer of glassy selenium is then formed on the bargain ^ aaetäk Takuuss ^ ifdasjßfuBg formed »laeh of the vorstafeeaden process a third Flatt · produced, at dft? Polystyrene as Strssehie & t al »· Rylcnsperrschicht is vergeeaHes.

The “three plates” were each tested by charging and illuminating el · on a · known · spanmmg ”. Then they sit down sparingly. If there is no charge accumulation in the plastic layer, the residual stress can be determined from the known “Sigasseiiafta” of the synthetic resin, the thickness of the layers, the difference in risk between the materials and the initial stress * calculated residual voltage should correspond to urned R "* t" pannuBg except for a *, peri "mtellen error,

209838/0952 »ad oriqihal

until the electrical flashover point reaches the plastic layer is · aan assumes that the initial field distribution is capacitive the residual stress TT _ is calculated according to the following

rea

Formula"

1+

If no charge is transported through the synthetic resin layer, the course of the experimentally determined residual stress Tres P ² * ⁰ ! * ⁰¹ *** · ⁰¹¹ *! de »curve of the voltage V ₀ (Jtafangsspanmmg), the gradient being designed as follows

In the above formula, k ^ is the dielectric constant of the bar, d ^ the thickness of the resin layer, kg the dielectric constant of selenium, Ö £ * ^ ^e biske of the selenium layer. The AnTange voltage is V _Q.

The reasoning is carried out using a single-colored light source with a wavelength of 4000 angular units and an intensity ταη Z χ 10 photons / oa / eek. "Each plate will have" more "selected voltages" know about 0.1 and 100 volts (approx S3 Yolt / Kikron) charged «The residual voltage is not limited by the incident ade light, since under all conditions a sufficient amount of light is available to generate a sufficient number of charge carriers in the selenium, reducing the field on the selenium layer practically to the value 0 χα . The thickness of the layers is intentionally kept low, even when thin samples cause prob reading with regard to the measurement. This realizes the actual situation of the recording media with a binder structure in which the electrical properties are thinner

' ^Ä '" ^w " 5Q9838 / 09S2 bad original

Films of plastic between the pigment parts of Influence are «The results of these calculations and experiments are listed in the following table I *

Table X

Electrical properties of layer structures

Polystyrene 2.4 1.0 0.77 (+) 0.01 0.83

Polyisobutylene etherylate 2.7 1.0 0.79 C +) 0.02 0.82

Silicone resin 2.8 1.0 0.70 (+) 0.02 0.81

Selenium 6 0.5

The values for the experimental slope are calculated using the least squares method from the experimentally determined points , 1955 t. The small normal error of the slopes shows that the individual points do not vary significantly compared to the best straight line. The comparison between our experimental values and the calculated or theoretical positions must then be carried out. Although the experimental and calculated slopes do not exactly match, they correspond well to one another if all errors are taken into account. Although the random errors of the measurements are small (i.e. the standard error of the slope), large systematic errors can also thaw because it is difficult to measure the layer thickness correctly

Based on the experimental data given in Table 1 , it can therefore be concluded that a negligible charge

BATH ORIGINAL

209838/0952

Displacement occurs in the three resin layers, even if theirs Thickness is only 1 micron »which for field strengths Me is approx. 45 volts / micron applies. At field strengths above approx. 45 volts / ktkren these thin layers show a dielectric breakdown. This experimental fixed does not show “whether the charge storage in an inability to take over the indicated defect electrons from the smooth selenium or in an "ore" Penetration depth or at a bad transport porter for the charge carrier lies * If all error limits are taken into account, it can be said earlier that these plastics act as insulators under the conditions of the thermoset tests, i.e. the charge is either not injected into the layer from the selenium or it is not injected through the layer is transported at the field strengths mentioned.

In order to demonstrate the advantages of the invention over ά & η known arrangements with combinations of at least two or more light-sensitive materials, using the excess sludge Patentscbriften 3,121,007 and 3,037,861 "be carried out further tests. If the active matrix material provided according to the invention absorbs part of the incident radiation during use, the recording beam becomes less sensitive, regardless of whether it consists of particles diapered in a binder or has a special photo-injecting rail. Apart from a decrease in the sensitivity to discharge, the utilization of the photoconductive properties of the active matrix material leads to serious problems with continuous use of the recording medium * for example in * Ib8V cyclically operating reproduction machines * It is normally desirable for the recording medium to have stable or stable electrical properties during cyclical use, in order to enable a corresponding construction of other components of the, for example the developing device, exposure device and the underground control. If these conditions cannot be maintained in an essentially constant manner, it becomes difficult and even impossible to build an automatically and reliably working copier machine which

209838/0952 BAD ORlQiNAL

2: 08939

-U-

No permanent maintenance and adjustment is required.Usa show this critical factor of the recording medium according to the invention only for iron levels in which the charge carriers are generated by the photoconductor and for which the surrounding matrix or the active material is transparent, the following test is carried out.

An adhesive bit is made of a quartz base on which a conductive tin oxide layer is provided. A 0.1 Huron thick barrier layer of epoxy resin is formed on the tin oxide layer, on which a 0 * 5 micron thick layer of amorphous selenium is created by vacuum evaporation. A 10 micron thick coating of polyvinyl carbazole is formed on the selenium layer.

The Platt "is olt charged to a negative voltage of approx · ¥ 200 and tested with four versoliiedenen wavelengths" by άβτ by the surface PolyvinylcarbazolseMcht is irradiated "Upon irradiation of the recording medium shows a characteristic" electrical discharge "curve" The xeregraphische Eapflnälichkeit of absorbing calibration Nungs - tvSgßvm can be judged * indaa the slope is Sntladungskurve la moment of Eeleueihtung gFaphiseh is eraittalt "ie the value" J | at t »o. The slope is normalized to the thickness of the sample and an irradiance of 1 × 10 photons / eir / sec ·. The calculation gives the discharge sensitivity listed in Table II below

BATH ORIGINAL

209838/0952

Table II

Dependence of the discharge rate on the Absorption with polyvinyl carbazole

wavelength ^V o (Angström ») (VoI 4000 205 3550 185 3340-3370 200 3150-3180 200 2720-2740 195

(Yolt / eek)

157 83 75 45 49

As can be seen from Table II, for 4000 angstrom units for which the polyvinyl carbazole is practically transparent, the discharge susceptibility (| g L _{mo is} relatively high. However, when exposed to wavelengths of 3550 angstrom units or less, some charge carriers are generated in the polyvinyl carbazole and the sensitivity is significantly reduced.

To the critical influence of the ongoing and repeated To show the use of the recording medium and the requirement To clarify the transparency of the active matrix material for the radiation used, further tests are carried out A 10 χ 10 om large aluminum underlay gets old at first a 0.2 micron thick epoxy layer is provided as a barrier layer »then a 0.5 micron thick layer of glassy Selenium formed on the barrier layer by vacuum absorption » on top of which a 12 micron thick polyvinyl arbazole layer is then applied. This plate is then placed on an aluminum oven drawn up with a diameter of 20 ca and charged to a negative! voltage of 900 ToIt We get a counter potential of 200 ToIt asu.

20983870952

The plate is then set to a negative voltage of 40 volts or less cleared by using a quartz iodine lamp is irradiated. Then it is charged again to a negative voltage of 900 volts. The cycle is then at a peripheral speed the drum repeated at approx * 15 em / sec. For all tests the initial voltage is set to 900 volts, by setting the corona current at the start of the test. The experiments are carried out with radiations of 4000, 3450 and 2537 angstrom units wavelength performed. In iodem Trap, the radiation intensity is adjusted at the beginning to generate 200 volts of contrast potential. The test results are shown in FIG.

As shown in Fig. 10, the structure is at one wavelength of 4000 Angstrom units, for which the polyvinyl carbazole is transparent and does not act as a photoconductor, in their electrical Properties stable for more than 1000 cycles. At a wavelength of 3450 and 2537 Angstrom units, their Radiation is strongly absorbed by the polyvinyl carbazole layer and in which the polyvinyl carbazole layer acts as a photoconductor acts, the initial voltage drops with cyclical use of the recording medium, and results from extrapolation that the recording medium was apparently after approx. 10 000 cycles no longer accept charge. Outside the range of these experiments, the potential drops after irradiation proportional to the drop in the initial voltage, resulting in a constant contrast potential. Developing a Such an image is possible to use the PotentialMndenmg Bit However, constant contrast leads to difficulties in development and background position, so that such Application in automatic electrophotographic reproduction machines is disadvantageous.

The above tests are readily applicable to structures in which the photoconductive particles are in an active binder matrix are dispersed or in which layered elements are provided, because the layer structures can

209838/0952

used in the same way to represent the processes that all around each Pigoentstofftellehen within an * active matrix occur.

The following examples serve to further specifically explain the invention and a recording medium a binder layer consisting of an active organic matrix and photoconductive particles dispersed therein, Percentages are by weight unless otherwise stated. The following examples represent some preferred Embodiments of the invention.

Example I.

A light sensitive recorder is made of the idle medium structure of the type shown in FIG. 7, non-oriented photoconductive particles of the X-form, metal-free phthalocyanine, which are photoconductive in a polyvinyl carbazole binder (FfE) with a weight ratio of 43 parts PVC to 1 part Pigment parts (volume ratio 60 t 1) are present. The recording medium is formed in the following way: 31 g of a 16.7-percent polyvinyl carafezol solution are formed, while a corresponding amount of Luvioan M170, a poly-N-Vlnyloarbazel from BASF _{9 is dissolved} in 180 g of toluene and 20 g of cyelohexanone. This J solution is added to 0.25 g of the X-form metal-free phthalocyanines and 10 g of toluene. This mixture is ground with Stahlsohrot for about 15 to 15 minutes until a well-dispersed suspension results. A layer is then formed on an aluminum backing using a coating device (Bird Applicator from Gardner Laboratory). The final layer thickness after air drying at 110 ° C for 1 to 24 hours is 24 microns.

“AD ORIGINAL

2Ü9838 / 0952

Example ΣΙ

Three record carriers are made according to the procedure described in Example I, the difference being that the bits Phthaloeyaninconientration has the following ratios ι

a) Weight ratio 72 ι 1 (volume ratio 90 t 1) of FVS to phthalocyanine with a layer thickness of approx.

20 microns,

b) Weight ratio 24 t 1 (volume ratio 30 H) of PTK to phthalocyanine, one layer is thicker than the above. 20 microns,

e) Weight ratio 96 s 1 (volume ratio 120 t 1) of PVC to phthalocyanine with a layer thickness of oa · 20 microns.

Example III

Three record carriers are produced according to the method described in Example I, the difference being that Instead of the phthalocyanine, a round, aromatic one Quinone is used, which is available from the Allied Chemical Corporation under the name Indofast Orange «This Pigaentstoff is present in the following proportions

a) Weight ratio 24 ι 1 (volume ratio 30 t 1) of

PVC to Plgsentstoff at a maximum thickness of approx. 13 microns,

b) Weighted seams 48 t 1 (volume ratio 60 ι 1) of PVC to Pigaentstoff with a layer thickness of approx. 15 microns,

c) Weight ratio 72 t 1 (volume ratio 72/1) of PVC to Pigaentetoff with a layer thickness of oa. 14 microns.

Example IV

Two recording media are prepared according to the method described in Example I with the difference that the pigment of I trigonal selenium is used in the following proportions

BAD ORIGINAL 209838/09 5 2

a) Weight / ratio 24 t 1 (volume ratio 96 ι 1) of PVC to trigonal selenium with a layer thickness of approx. 30 microns,

b) Weight ratio 48 s 1 (voltaic ratio 192: 1) of PVC to trigonal selenium with a layer thickness of about 12 microns.

Example V

A record carrier is made according to that described in Example I. Process produced with the difference that the pigment foselenide with a weight ratio of 24 ι 1 (volume *

ratio 105 J 1) of PVC to cadmium sulfoselenide used will. The thickness of the layer is approx. 10 microns.

Example VI

A record carrier is made according to that described in Example X. Process produced old the difference that as a pigment substance trigonal selenium with a weight ratio of 24 ι 1 (yoIumen ratio 96 t 1) is used by PVC to trigonal selenium. The layer thickness is approx. 10 microns. Furthermore is a 0.2 micron nylon barrier on the surface of the Blinder layer and at the interface between binders and underlay provided. The Kylon barrier is made by immersing the plate in a Hylon solution in methyl alcohol (available from DuPont under the name Zytel) formed ·

Example VII

A record carrier is prepared by the process described in Example 1 with the difference da0 as Pigsent "toff trigonal selenium with a weight ratio of 24 t 1 {Volu * ·" - relationship 9β ι is 1) is used from PVK to tr5.goTialeni selenium. The layer thickness is approx. 9 hikron.

209838/0952 "ADOR _{lelNA (} .

Example TXXX

A recording medium is produced according to the method described in Example X, with the difference that the pigment substance used is trigonal selenium with a weight ratio of 6 s 1 (volume ratio 24 t 1) of FRP to trigonal selenium. The layer thickness is approx. 10 microns

Each of the recording media described in Examples X to VIII has excellent electrical properties show themselves by a good charge absorption capacity and a good photosensitivity. The profit or the maximum The efficiency for seven of the recording media formed according to the preceding examples is shown in Table XXX.

The recording media listed in Table XXX are electrostatically charged to a positive voltage with the specified field strength (a field strength of 50 10 volts / approx. Corresponds to a voltage of 50 χ 10 volts for every centimeter of the wire thickness), for which a corona discharge device is used . Each sample is then exposed to a monochromatic light source whose wavelength is close to the peak absorption of the photoconductive pigment used in each case. The resulting discharge (voltage over time) is recorded. From this data, the xerographic gain can be calculated using the formulas given above.

Table XXX

Profit or performance (per absorbed

Plate wavelength Photon flux El.field Photon collected from (Angstrom) (Photons / (1O ⁴ V / cm) charge carriers) Example car / sec)

I 6200 6.5 x 10l | 50 0.26 IXa 6200 6.5 x 10Jf 50 0.23 lib 6200 8.0 χ 10 ^Ί * 8- 95 0.35

209838/0952

BAD ORlQl ^ L

ZV a 4000 IVa 4000 IVb 4000 VIII 4000

3 * 8 x 1o1 | 10-70 0.25

2.0 ζ 1OiX 25 0.20

5.9 x 104 | 30 0.22

5.9x10 ^7Z 30 ₀

In addition to the tests listed in Table III, three of the recording media are subjected to image reproduction. XMLe plate atm example IVa is electrostatically charged positively to about 800 volts, for which purpose a corona discharge charge is used The electrostatic latent image produced is then developed, for which a liquid development is carried out in which electrostatically negatively charged toner particles, which are dispersed in kerosene, are moved over the latent image. The electrostatically charged areas of the latent image attract the toner particles and create a visible image.

The plate from Example VI is described as described above The process is provided with a »picture, but it is charged to a voltage of approx. 500 volts.

The plate from example V is also provided with an image according to the method described above, but is charged them to a voltage of 500 volts, then the development is done according to the Xerox 914 toner each of these three plates produces an excellent reproduction of an original image

In order to illustrate the properties of the recording media according to the invention with regard to cyclical and repeated use, the disks from Examples I, IIIa and IVa

BAD ORtGlNAt 20Ö838 / 0952

used cyclically · First of all, they are electrostatically charged in the dark with a field strength of approx. 30 volts / micron of the binding agent strength. The plates I, IXIa and ZTa «then ground bit wave lengths of 620O ₉ 4000 and 4000 Angstroms in units exposed * with a flow of photons for the discharge

12 2

approx. 2 χ 10 photons / cm / eek is generated · After that each Plate with white light to remove any residual charge lit · This entire cycle is repeated 200 times for plates I and IVa and 250 times for plate XIIa. Each plate shows excellent charge acceptance and discharge capability through the effects of light at the end of this cyclical testing · The Aefangsspanmsig, the contrast spaüanung and the residual voltage are practically the same at the end of the test like after the first cycle.

Example XX

CELas-shaped SelenkBraer bits with a purity of 99.999 % (obtainable from the American Smelting and Refining Co.) are worn in a transverse vessel and placed in a pressure chamber in which there is a pressure of approx. 10 ^-1 Torr. The selenium is approx. 16 Treated at up to 100 ° C for hours »to transform it from the glassy state into the crystalline trigonal · form ·

A mixture of 1 yoiumena & partially trigonal selenium and 1 volume part of poly-1 «viaylpyrene (FfP) is in 100 parts Reagent "chlorofrm dispersed" This envelope is used in a Paint mill for 1 hour with a steel rod 3 mm in diameter ground until the selenium particles have a maximum size of not more than approx. 1 micron Then as much FfP is added, until there is a ratio of PfP to selenium of 24 t 1 This flour is ground approx. 30 Kixnrfcen long and on three

applied as a layer, whose

dry starch amounts to 23 milligrams each. Every document is Bit of a 0.2 micron thick Spaaqre lock is provided on

209838 / 09S2 _B a _{& O} ri _S1 nal

which the binding post is applied

Each of these plates is electrically tested. «All plates show good electrical discharge capacity.

Although in the above description preferred embodiments of the invention, specific proportions and quantities of matter have been described, other suitable substances and types of processes, as listed above, with similar results can also be used Substances and modifications should be provided that create a synergistic, show improving or otherwise beneficial effect on the respective recording medium and its production. If, for example, a transparent base is used in the form of a plastic carrier provided with a thin conductive layer of aluminum or tin oxide, then a Exposure of the recording medium can take place through the substrate. An electrically insulating substrate can also be used In this case, the charge is applied to the record carrier by placing the insulating substrate and the surface of the record carrier at the same time with opposite polarity due to double corona discharge to be charged · Other modifications of an insulating or lack of a base can be provided, the recording medium or the plate being placed on a conductive base and then the surface of the recording medium being charged. After the image generation, the recording medium can then be removed from the conductive substrate.

BAD ORiGiNAL

209838/0952

Claims (14)

Claims 1. Drawing tiger with photoconductive «· insulating layer, characterized in that the photoconductive * insulating material layer (12) is a binder layer made of in one electrically active organic matrix material (14) dispersed and non-oriented photoconductive particles (13) exists which, when exposed to light, are excited to form defect electrons, and these are transferred to the one receiving them and inject matrix material (14) which enables their transport, and the proportion of photoconductive particles (13) 0.1 to 5 percent by volume of the binder layer (12). 2. Recording medium according to claim 1, characterized in that that the active matrix material (14) contains at least one of the following substances poly-1-vinylpyrene, polymethylpyrene, N-substituted polymeric acrylic acid amides of pyrene, pyrene, Tetraphene, 1-aoetylpyrene, 2,3-benzochrysene, 6,7-benzopyrene, 1-bromopyrene, 1-ethyl pyrene, 1-methyl pyrene, perylene, 2-phenylindole, tetraene, pleen, 1,3,6,8-tetraphenyl pyrene, Chrysene, fluorene, fluorenone, fhenanthrene, triphenylene, 1,2,5,6-Dlbenzanthraoen, 1,2,3,4-Dibenzanthracene, 2,3-Benzopyrene, 2,3-Benzoohrysene, Anthraquinone, Dibenzothiophene, Haphthalene 3. Aufzeichaungträger according to claim 1, characterized in, that the matrix material (14) is a polynuclear, aromatic Connection contains 4. Recording medium according to one of the preceding claims, characterized in that the photoconductive particles (13) with a proportion of the above. 0.1 to 1.0 percent by volume of the make coat (12) are present. 5. On recording medium according to one of the preceding claims, characterized in that the binder layer (12) is arranged on a base (11). 209838/0952 8AD ORIGINAL 6. Record carrier according to claim 5 »daduroh marked» dad the base (11) is electrically conductive. 7. Record carrier according to one of the preceding claims, characterized in that the binding sheet (12) is open a transparent base (11) is arranged. 8. Recording medium according to one of the preceding claims »characterized in that the photoleltbaren particles (15) contain at least one of the following substances! glassy uraiges selenium «selenium alloy, trlgonal ^ s selenium, Cadaiuasui foselenld, the X-Fora metal-free phthalocyanine * _β 9 · Image generation process using a recording medium designed as one of claims 1 to 3, characterized in that the free surface of the binding medium layer (12) is equally electrostatically charged and irradiated with old, imagewise distributed activating radiation which is emitted by the photoconductive layers ( is absorbed 13) and the matrix material (14) is not absorbed so that injected through Llchttnregtmg in the fotoleitfShigen part away (13) generated holes la the matrix material (14) and transported in "ground and u 'free ip surface a latent electrostatic MId arises * 10. The method according to claim 9, characterized in that »the latent image is developed to produce a visible image will. ^ 11. The method according to claim 9 or 10, characterized in that an activating radiation within the visible spectrum is used. 12. The method according to claim 9 or 1O ₉ daduroh characterized in that a radiation bit of a wavelength of about 4000 to 8000 is used· 13. The method according to one of claims 9 to 12, characterized in that a binding agent layer (12) is used on a transparent base (11) and that the action is taken the radiation takes place through the base (11). 14. A method according to one of claims 10 to 13 »characterized in that the charging t" irradiation and image development are repeated at least once. 209838/0952 SS Blank page