DE1572371C3 - Electrophotographic recording material - Google Patents

Description

contains, wherein X and Y are each equal to a hydrogen atom or an alkyl group, the total number of carbon atoms in X + Y being at most 12 and η being 2 or a greater number.

2. Recording material according to claim 1, characterized in that the charge transfer complex as an electron donor a polyphenylene oxide of the formula

contains, wherein η is equal to 50 or a greater number.

3. Recording material according to claim 1, characterized in that the charge transfer complex from 1 to 100 parts by weight of electron donor per part by weight of electron acceptor consists.

The invention relates to an electrophotographic recording material having a photoconductive one Layer that contains a charge transfer complex as a photoconductor.

Electrophotographic reproduction is known and for example in US-PS 23 57 809 and 91 011 and 30 79 342. It is also known for making electrophotographic Recording materials, photoconductive insulating materials, such as anthracene, sulfur, selenium or mixtures thereof to use. Of the substances mentioned, selenium has the most favorable properties, albeit the sensitivity spectrum of selenium only to the ultraviolet, blue and green spectral ranges is limited and the production of recording materials with vitreous selenium cost-intensive and requires procedural steps that are technically difficult to master.

It is also already known to use inorganic photoconductive layers to make photoconductive insulating layers To produce pigments, these pigments being dispersed in suitable binders. Furthermore are already eiekirophotographic recording materials in use comprised of organic photoconductive dyes as well as a large number of polycyclic Connections exist together with a suitable synthetic resin.

An electrophotographic recording material of the type mentioned, in which the Photoconductor containing a charge transfer complex is already known from DT-AS 11 97 325. This known recording material consists of

ίο a support and a photoconductive layer with a photoconductor made from a condensation product of an aldehyde and an optionally substituted aromatic amine, with a high molecular weight condensation product as a photoconductor the aldehyde and the optionally substituted aromatic amine is provided, which photoconductor contains small amounts of activators to increase its sensitivity to light. As activators organic compounds are provided in the known recording material, which in molecular complexes of the donor-acceptor type act as electron acceptors serve. These activators are compounds with a high electron affinity and Acids as defined by Lewis. These activators are the high molecular weight condensation product of an aldehyde and an optionally forming the known recording material substituted aromatic amine added in small amounts.

A disadvantage of this known recording material is that during production at least one already photoconductive starting material must be used and that the In addition to their high production price, recording materials produced in this way are also unsatisfactory Have adhesiveness of the photoconductive layer to a metal substrate. Furthermore, the known recording materials to warp even at relatively low temperatures, see above that they are sometimes considerable in commercial duplicating machines because of the prevailing in them cannot be used at high temperatures. In addition, these show known recording materials often suffer from the disadvantage that they rapidly decrease their electrophotographic properties age and also have relatively uneven surfaces, making cleaning difficult. The guarantee optimum electrophotographic and physical properties are used in the manufacture of the known recording materials limited in that only insulating materials can be used are self-photoconductive.

The object of the invention is to provide an electrophotographic To create recording material of the type mentioned, which is based on Can produce economically advantageous manner, a high mechanical resistance and a relative has a high deformation temperature.

According to the invention, this object is achieved in that the charge transfer complex acts as an electron donor a polyphenylene oxide of the formula

contains, wherein X and Y are each equal to a hydrogen atom or an alkyl group, the total number of carbon atoms in X + Y being at most 12 and η being 2 or a greater number.

The electrophotographic recording material according to the invention allows the production of a self-supporting and binder-free photoconductive layer, which is surprisingly characterized by that it consists of initially non-photoconductive substances. Another advantage of the invention Recording material can be seen in the fact that the transparent self-supporting photoconductive obtained Layer even without the use of a conductive base for electrophotographic reproduction suitable is.

In the electrophotographic recording material of the invention, serves in the charge transfer complex the polyphenylene oxide with the given structural formula as an electron donor and a Lewis acid as an electron acceptor.

According to one embodiment of the invention it is provided that the charge transfer complex as Electron donor a polyphenylene oxide of the formula

contains, wherein η is equal to 50 or a greater number.

Furthermore, it has been found to be particularly advantageous that the charge transfer complex from FIG up to 100 parts by weight of electron donor per part by weight of electron acceptor.

It should be underlined that neither said electron donor nor said electron acceptor inherently has photoconductive properties. The Lewis acid serving as an electron acceptor contains strongly polarizing groups that bind or attract the electrons involved in the Formation of a chemical compound or, as in the present case, a charge transfer complex from the electron donor such as a Lewis base.

In the context of the present invention, the term "Lewis acid" is to be understood as meaning any substance which binds or attracts the electrons supplied by a reaction partner.

To produce the electrophotographic of the present invention Recording material is the non-photoconductive electron acceptor with the as Electron donor polyphenylene oxide of the formula given mixed or otherwise brought together, thereby forming an excellent photoconductive layer with good insulating properties is carried out either as a self-supporting layer or applied to a suitable base can be.

Under a charge transfer complex is a composition of neutral electron donor and To understand acceptor molecules, which are characterized by the fact that an internal electron transfer through photoexcitation is caused, which causes a temporarily excited state in which the donor is more positive and the acceptor is more negative than in the initial state.

It is believed that the non-photoconductive polyphenylene oxide is caused by the formation of the charge transfer complex becomes photoconductive with the help of electron acceptors or Lewis acids and that such complexes represent the photoconductive elements of the recording material after their formation.

Generally speaking, charge transfer complexes are loose assemblies of electron donors and acceptors, often in stoichiometric proportions, which are present as follows:

a) The donor-acceptor interaction is weak in the neutral initial state; h., neither The donor and the acceptor influence each other significantly in the absence of photoexcitation.

b) The donor-acceptor interaction is relatively strong in the photoexcited state; h., the Components are at least partially ionized by photoexcitation.

c) When the complex is formed, one or more new absorption bands appear in the near ultraviolet or visible range (wavelengths between 3200 and 7500 angstrom units), which neither in the donor nor in the acceptor alone

are present, but a property of the donor-acceptor complex represent.

The self-absorption bands of the donor and the charge transfer bands of the complex can both can be used to stimulate photoconductivity.

Under the designation "photoconductive insulating material" is the practical use in electrophotographic Understand image production. It is generally assumed that any isolator through Excitation can be made "photoconductive" by means of sufficiently intense radiation of short wavelength can. This definition applies generally to inorganic and organic substances, including neutral ones Binder resins for recording materials bound by binding agents and electron-binding materials Activators and aromatic resins used in the present invention. However, the sensitivity to short-wave radiation is not useful in practical image production, because sufficiently strong radiation sources with wavelengths below 3200 angstrom units are not are available and such radiation that human eye is destroyed and absorbed by the glass of optical systems. Therefore relates the designation "photoconductive insulating material" for the present invention only applies to those substances marked as follows: You are

1. Can be used to form continuous films which, in the absence of activating radiation, produce a Store electrostatic charge, and it is

2. the sensitivity of these films to exposure at wavelengths greater than 3200 angstrom units, being with an overall exposure

at least a 50% discharge is achieved by a maximum of 10 ¹⁴ quanta / cm ^{a of absorbed radiation.}

This definition defines the electron donors and acceptors of the present invention differentiated from the general term »photoconductive insulating materials«.

Any suitable may be used in the present invention

5 6

Polyphenylene oxide resin can be used. An opnaphthenquinone dichloride, anisil, 2,2-pyridil and furil. maximum sensitivity is obtained when a resin is used. Other Lewis acids are mineral acids, such as the is used, which by catalytic oxidation of hydrohalic acids, sulfuric acid and phosvone 2,6-xylene is made with copper. As a result, phosphoric acid, carboxylic acids such as acetic acid and their the result is a resin which, as components X and Y, contains 5 substitution products, monochloroacetic acid, dichloro General formula given above, methyl acetic acid, trichloroacetic acid, phenylacetic acid and contains groups. For optimal physical proper 6-methylcoumarinyl acetic acid (4); Maleic acid, cinnamon is a molecular weight between 25000 acid, benzoic acid, l- (4-diethylaminobenzoyl) -ben- and 30,000 cheap. In addition to the preferred 2-carboxylic acid, phthalic acid and tetrachlorophthalic acid 2,6-Xylenol can be any other suitable io acid, «, / S-dibromo-ß-formylacrylic acid (mucobromo-phenol used to make resins. acid), dibromomaleic acid, 2-bromobenzoic acid, GaI-typical Phenols are phenol, 2-methylphenol, lussic acid, 3-nitro-2-hydroxy-l-benzoic acid, 2-nitro-2-propylphenol, 2-isobutylphenol, 2,6-diethylphenol, phenoxyacetic acid, 2-nitrobenzoic acid, 3-nitroben-2,6-diisopropylphenol, 2-ethyl-6-methylphenol etc.zoic acid, 4-nitrobenzoic acid, 3-nitro-4-ethoxyben-

To form the electrophotographic record- 15 zoic acid, 2-chloro-4-nitro-1-benzoic acid, 2-chloro-4-nitro

tion material according to the invention or the inventio-1-benzoic acid, 3-nitro-4-methoxybenzoic acid,

appropriate photoconductive layer can be any 4-nitro-l-methylbenzoic acid, 2-chloro-5-nitro-l-ben-

suitable Lewis acid with the above-mentioned silicone-zoic acid, 3-chloro-6-nitro-1-benzoic acid, 4-chloro-3-ni-

resins are brought together. The mechanism tro-1-benzoic acid, S-chloro-B-nitro ^ -hydroxybenzoe-

the chemical interaction with the inventive 20 acid, 4-chloro-2-hydroxybenzoic acid, 2,4-dinitro

according to the manufacturing process is not completely 1-benzoic acid, 2-bromo-5-nitrobenzoic acid, 4-chloro

clarified. It is believed that a charge super- phenylacetic acid, 2-chlorocinnamic acid, 2-cyano cinnamic acid,

carrying complex is formed, the absorption of which is 2,4-dichlorobenzoic acid, 3,5-dinitrobenzoic acid,

bands none of the two starting materials individually 3,5-dinitrosalicylic acid, malonic acid, mucic acid,

correspond. The mixture of the two non-photo- 25 acetosalicylic acid, benzilic acid, butane-tetracarboxylic acid,

conductive substances seem to have an effect, citric acid, cyanoacetic acid, cyclohexanedicarboxylic

which goes far beyond an additive effect. acid, cyclohexenecarboxylic acid, 9,10-dichlorostearic

The best results will be with the following acid, fumaric, itaconic, levulinic, apple Lewis acids obtained: 2,4,7-trinitro-9-fluorenone; Te- acid, succinic acid, α-bromostearic acid, citracontrachlorophthalic anhydride, 9- (dicyanomethylene) -2,4,7-tri- 30 acid, dibromosuccinic acid, pyrene-2,3,7,8-tetracarnitrofluorenone; 2,3-dichloro-1,4-naphthoquinone and boric acid and tartaric acid, organic sulfonic acids, their mixtures. such as 4-toluenesulfonic acid, benzenesulfonic acid, 2,4-di-

Other typical Lewis acids are quinones, such as nitro-l-methylbenzene-6-sulfonic acid, 2,6-dinitro-l-hy-

p-benzoquinone, 2,5-dichlorobenzoquinone, 2,6-dichloro-droxybenzene-4-sulfonic acid, 2-nitro-1-hydroxybenzene-

benzoquinone, chloranil, naphthoquinone- (1,4), 2-Me- 35 4-sulfonic acid, 4-nitro-1-hydroxy-2-benzenesulfonic acid,

thylanthraquinone, 1,4-dimethylanthraquinone, 1-chloro- 3 - nitro - 2 - methyl -1 - hydroxybenzene - 5 - sulfonic acid,

anthraquinone, anthraquinone-2-carboxylic acid, 1,5-di- 6 - nitro - 4 - methyl -1 - hydroxybenzene - 2 - sulfonic acid,

chloranthraquinone, l-chloro-4-nitroanthraquinone, phen- 4 - chlorine -1 - hydroxybenzene - 3 - sulfonic acid, 2 -chloro-

anthrenequinone, acenaphthenquinone, pyranthrene-3-nitro-1-methylbenzene-5-sulfonic acid and 2-chloro

non, chrysenequinone, thionaphthenquinone, anthra- 40 l-methylbenzene-4-sulfonic acid.

quinone-1,8-disulfonic acid and anthraquinone-2-aldehyde, the following examples serve to further Er-triphthaloylbenzene, aldehydes, such as bromal, 4-nitro refinement of the present invention. Proportions and benzaldehyde, 2,6-dichlorobenzaldehyde-2, ethoxy percentages relate to the weight, unless 1-naphthaldehyde, anthracene-9-aldehyde, pyrene-3-aldehyde is stated otherwise. The examples show some hyd, oxindole-3-aldehyde, pyridine-2,6-dialdehyde, Bi- 45 preferred production methods of the phenyl-4-aldehyde according to the invention, organic phosphonic acids, such as electrophotographic recording material.
4-chloro-3-nitrobenzenesophosphonic acid; Nitrophenols, in each example the substance produced is in such as 4-nitrophenol and picric acid; Acid anhydrides, dissolved form with suitable devices on a z. B. acetic anhydride, succinic anhydride, Ma- conductive pad applied and dried. The linic anhydride, phthalic anhydride, tetrachloride recording material produced in this way is gephthalic anhydride, perylene-S ^^. 10-tetracarbon-earthed and the layer is described in the dark by means of an acid and chrysene ^^ S ^ -tetracarboxylic anhydride, corona discharge device; Metal halides of the s o η in US-PS 25 88 699) charged to saturation chip metals and metalloids of groups IB, II to VIII voltage. For this purpose a radiation discharge of the periodic system, e.g. B. aluminum chloride, 55 scorotron is used, which is fed by a high-voltage zinc chloride, iron (TII) chloride, tin tetrachloride, ar device, which supplies a voltage of 7 KiIosentrichlorid, tin (II) chloride, antimony pentachloride, volt. The control electrode voltage is magnesium chloride, magnesium bromide, calcium bromide 0.9 kilovolt and is generated by a regulated equilibrium, calcium iodide, strontium bromide, chromium (III) voltage device (0 to 1500 volts). The charging time bromide, manganese (II) chloride, cobalt (II) chloride, Ko-60 is 15 seconds.

balt (III) chloride, copper (II) bromide, cerium (IV) chloride, after charging the electrostatic chip is thorium chloride, Arsenic triiodide, boron halogen compound then with a transparent electrometer, z. B. boron trifluoride and boron trichloride, and ketones, probe measured without touching the layer or such as acetophenone, benzophenone, 2-acetylnaphthalene, affect the cargo. That in the probe through Benzil, benzoin, 5-benzoylacenaphthene, biacendione, 65 the signal generated by the charged layer is amplified 9-Acetylanthracen, 9-Benzoylanthracen, 4- (4-Dime- and fed to a scribe. Those with the scribe thylamino-cinnamoyl) -l-acetylbenzene, acetoacetic acid- directly recorded curve shows the size of the anilide, indanedione- (1,3), (1,3-diketohydrinden), Ace- charge on the layer and its drop over the

Time on. After about 15 seconds, the layer is exposed by shining through the transparent probe will. For this purpose, a microscope illumination is used with an incandescent lamp with a color temperature of 2800 ° K is working. The illuminance is measured with a light meter and entered in the table recorded. The discharge speed upon exposure will be for 15 seconds or up to Achieving a constant residual potential measured. The illuminance in each example is about 613 lux.

The numerical difference in the rate of discharge of the layer over time during exposure and the rate of discharge of the layer in the dark is a measure of the layer's sensitivity to light.

A test is also carried out on each material for photoconductivity. A Electrophotographic image is formed by charging by means of corona discharge, exposure by projection of a light-shadow image and cascading development of the electrostatic latent image Using the method described in US Pat. No. 2,618,551. Details of this process are given in example I.

Example I.

About 4 parts of a polyphenylene oxide resin with the general formula

Example II

A coating solution was prepared as described in Example I with the difference that 0.1 part of a triphenylmethane dye with the color index no. 662 were added to the solution. The solution was applied to an aluminum plate in the manner described and in an oven at a temperature of 100 ^° C. for about 30 minutes

ίο exposed.

The recording material was loaded, exposed and developed as described in Example I, and the image was carried through on the plate surface Meltdown fixed. The developed image corresponded to the original image.

Another part of the recording material was tested with the electrometer in the manner described, and the results are included in the table. As can be seen from this, the

ao sensitivity spectrum and light sensitivity of the recording material has been improved by adding the sensitizing dye.

Example III

A coating solution was prepared as described in Example I with the difference that the 2,4,7-trinitrofluorenone was absent. The solution was applied to an aluminum plate and exposed to ^{a temperature of 100 ° C. in an oven for about 30 minutes.} The recording material was charged, exposed and developed as described in Example I without an image being seen. Another part of the material was measured with the electrometer and the results were recorded in the table. As can be seen from this, the recording material shows no photosensitivity without the Lewis acid.

were dissolved in about 50 parts of dichlorobenzene. To this solution was added a solution which from one part of 2,4,7-trinitro-9-fluorenone dissolved in a mixture of about 10 parts of cyclohexanol and consisted of about 20 parts of dichlorobenzene. The solution was made to a thickness of about 5 microns 0.13 mm thick cast aluminum plate. The coating layer was dried and then about Exposed to a temperature of about 100 ° C for 30 minutes.

A portion of the recording material thus produced was turned negative to about 250 volts by means of a corona discharge device charged according to US-PS 25 88 "699 and then exposed for about 15 seconds, including an enlarger with optics and a tungsten filament lamp with a color temperature of 2950 ° K has been used. The exposure was approximately 2690 luxsec. The latent image was then created using the cascading process developed. The developed image was electrostatically transferred to an image base, for which the method described in US Pat. No. 2,576,047 was used. The one available on the pad The image was the same as the original projected image. The recording material was left with Toner cleaned and used repeatedly in the above manner.

Another part of the recording material was measured in the manner described with the electrometer were measured and the results were recorded in the table.

Example IV

A coating solution was prepared as described in Example I with the difference that 9- (dicyanomethylene) -2,4,7-trinitrofluorenone was used in place of the 2,4,7-trinitrofluorenone. The solution was applied to an aluminum plate and exposed to ^{a temperature of 100 ° C. in an oven for about 1 hour.} Part of the recording material was charged, exposed and developed as described in Example 1. A good quality positive image was obtained. Another part of the material was measured with the electrometer and the results were recorded in the table.

B e i s ρ i e 1 V

A coating solution was prepared as in Example I with the difference that instead of the 2,4,7-trinitrofluorenone 2,3-dichloro-1,4-naphthoquinone was used. The mixture was placed on an aluminum pad applied and subjected to a heat treatment. The recording material was charged, exposed and developed as described in Example I. The result was a positive image of good quality.

Another portion of the material was measured with the electrometer and the results were entered into the Table added.

Example VI

About 2 parts of an ethyl methacrylate resin were dissolved in about 10 parts of methyl ethyl ketone. The solution

609 619/37

was applied to an aluminum plate about 5 microns thick and subjected to a heat treatment exposed. The recording material was measured in the manner described with the electrometer, and the results are included in the table.

This material served as a comparison material. As can be seen from the table, this resin possessed if it was used alone, no photosensitivity.

Example VIl

About 0.2 parts of 2,4,7-trinitrofluorenone were added added to the resin solution described in Example VI. This solution was on an aluminum plate applied to a thickness of about 5 microns and dried. The plate was made with the electrometer

10

measured, the results were recorded in the table.

The plate showed that the addition of a Lewis acid to a neutral resin did not show photosensitivity causes. This proves that Lewis acids alone are not photosensitive.

Example VIII

A recording material was produced according to Example VI, with the difference that about 0.1 part of the triphenylmethane dye with the color index no. 662 were added. The material was tested with the electrometer in the manner described and the results in the table recorded. This example shows that the sensitizing dye as used in Example II is not sensitive to light on its own.

example At first
voltage Healing discharge Dark
discharge Residual stress
after 15 seconds sensitivity
( ^(V) \ (Volt) (Volts / sec) (Volts / sec) (Volt) \ 100 lux sec / I. + 160
-300 16.0
64.0 6.0
1.8 + 90
- 70 1.637
10.15 II +205
-285 120
268 8.0
6.6 + 60
- 70 18.3
42.6 III +320
-200 0
0 0
0 + 320
-200 0
0 IV +440
-570 50.1
42.0 5.3
4.5 +215
-260 73.2
77.5 V +360
-410 8.0
8.8 4.0
4.0 +270
-300 0.669
0.715 VI +460
-500 4.4
5.2 4.4
5.2 +390
-410 0
0 VII +420
-460 0
0 0
0 +420
-450 0
0 VIII +310
-330 0
0 0
0 +310
-330 0
0

In the table above, the sensitivity denotes the initial discharge rate at Exposure in (volts / 100 lux.sec) corrected for dark discharge.

As can be seen from Examples I, II, IV and V, the mixture is a polyphenylene oxide resin and a Lewis acid photoconductive. Example III shows that a polyphenylene oxide resin alone is not conductive is. Example II shows that a substance consisting of polyphenylene oxide resin and a Lewis acid with can be sensitized to a dye. As can be seen in Example VI, this is ethyl methacrylate resin not photoconductive. Example VII shows that the Lewis acids used in Examples I and II in a neutral ethyl methacrylate resin binder are not photoconductive.

Although specific substances and conditions have been described in the preceding examples, the Invention not limited to this. Numerous other compositions, e.g. B. from the others above specified substances as well as numerous other manufacturing values can be used instead of those in the examples can be applied with similar results. The photoconductive layer according to the invention may contain further substances or coloring agents to improve the photoconductive properties to improve and / or a sensitization,

to achieve an adjustment or some other change. The photoconductive layer or the charge transfer complex according to the invention can also be used in other imaging processes.

Many other embodiments of the present invention will be apparent to those skilled in the art to the knowledge of Description possible within the scope of the invention.

Claims (1)

15 72 claims: 1. Electrophotographic recording material having a photoconductive layer, which as Photoconductor contains a charge transfer complex, characterized in that the charge transfer complex as electron donor is a polyphenylene oxide of the formula