DE1522596A1 - Electrophotographic photosensitive material - Google Patents

Description

W ₀ 12 475/66

Ii ■

Dr. Expl

Fuji Shashin Film Kabushiki Kaisha Kanagawa (Japan)

Electrophotographic, photosensitive material

The invention relates to an electrophotographic photosensitive material, and more particularly to the light-sensitive component used for electrophotography «,

In particular, the invention relates to providing one suitable for repeated use photosensitive component, - which is an insulating, photoelectric layer with high hardness and great mechanical and chemical resistance.

Some photoelectric, inorganic compounds and elements are known to be insulating, photoelectric Layers for electrophotography can be used. Examples are sulfur, selenium, oxides, Sulphides and selenides of zinc, cadmium, mercury, antimony,

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Bismuth and Lead and Titanium Oxide “These materials will usually in the form of layers on base plates or bases or supports made of metal, paper or plastics applied. In some cases these materials will dispersed in electrically insulating, film-forming binders and formed into insulating, photoelectric layers. Among these materials are selenium and zinc oxide best known and most generally put to practical use «, The other materials are scarcely used used and are hardly described,

In the production of elektrophotograchischen image using such a material are electrostatic charges of the coated surface, for example by means of a corona discharge, issued, whereby it is given a photosensitivity ₀ Then, this is sensitized in this way or sensitized, coated layer, _o h _o the insulating photoelectric layer, exposed in the usual way. An electrostatic latent image is developed into a visible image by the application of finely divided, charged, colored resin particles, the latent

Image obtained by exposure was «The finely colored

parts / heart particles are directly on the photoelectric, insulating layer or after transferring the resin particles to another suitable carrier by means of heat,

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Solventi print or protective coating fixed. In the case of transmission that is fine, away _r on the surface of the insulating, photo-electric layer after transfer residual powder and the insulating, photo-electric layer can be reused = The process described above for the preparation of an electrophotographic image is typically and most other procedures are derived from this accordingly. However, the electrophotographic photosensitive material according to the invention is not limited to use for only a particular electrophotographic process »

The well-known and practically used selenium is in the form of a vitreous selenium layer on a metal plate, particularly applied to an aluminum plate and is used as an electrophotographic photosensitive material suitable for repeated use It has the highest sensitivity of electrophotographic light-sensitive materials according to ASA 2-10 »Vitreous selenium has a high hardness and is due to its mirror surface is particularly suitable for repeated use. The other well known and practical In contrast, the zinc oxide used is dispersed in an electrically insulating resin binder on paper applied and dried to form an electrophotographic material, namely a photosensitive paper » This photosensitive paper has a

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Sensitivity from ASA 0.01 - 0.2 and leads to direct

of formation of images fixed on it, which / practically knows can be obtained. This layer containing zinc oxide in dispersed form can be applied to a metal substrate. However, since the hardness and sensitivity are low, this material is below the photosensitive component Use of selenium is greatly inferior and has not been of practical use as a photosensitive material for for repeated use * In addition to the low hardness and the low sensitivity, the

Deterioration of its properties or characteristics, associated with exposure, a further weakening or decrease in resistance to repeated Use, In addition to selenium and zinc oxide, only titanium oxide has recently been considered with regard to its usability, while the remainder are far removed from practical application in spite of the reports available in the literature are ο

Although the photosensitive ^u elenkomponente which is suitable for repeated use, has excellent properties in terms of sensitivity, hardness of the photosensitive layer and the Vorbelichtungseffektes, the drawbacks listed below are inevitable, "^ ie manufacture is very difficult. That intended for an insulating, photoelectric layer for sheet metal photography or a photosensitive layer

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and suitable selenium is vitreous and is applied in the form of a uniform layer on a base, e.g. on aluminum ", applied by vacuum vapor deposition" Therefore, a large facility is required for their manufacture, resulting in low production efficiency other properties should be added, which result from the vapor deposition under vacuum _β In addition, the deterioration of the properties is promoted and the useful life is shortened at high temperature and high humidity, since vitreous selenium belongs to a solid phase of selenium obtainable under supercooling conditions and tends to crystallize when contaminated with moisture or other materials or under the influence of heat In the case of zinc oxide, a coloring agent is often added to sensitize it, but this coloring agent is so thermally unstable that the deterioration in properties due to repeated w Repeated corona discharge and the irradiation with light during exposure rapidly assumes considerable proportions and the useful life or service life is significantly shorter than that of a photosensitive selenium material

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The object of the invention is to provide an electrophotographic, photosensitive material in which the above-mentioned disadvantages, the difficulties in the production of photosensitive selenium materials and their low resistance to heat and impurities and the low sensitivity, low hardness exhibited by zinc oxide photosensitive materials Lichtemf / pindlichen layer and film and the shortcomings related to the Yor exposure effect and in the thermal Stability are avoided »In particular, the object of the invention is to create an insulating, photoelectric Layer, especially an electrophotographic photosensitive component of equal or higher value Sensitivity than that of selenium photosensitive materials and a great hardness in the photosensitive Layer which is thermally very stable, has essentially no pre-exposure effect, when repeated Use is persistent and can be easily generated ο

The electrophotographic photosensitive material according to the invention is characterized in that a insulating, photoelectric layer that is dispersed by applying an electrically insulating binder, finely divided, photoelectric material was obtained on a carrier and a thin layer mit'er

Thickness of less than 5 microns, consisting only of the same or a similar binder as the electrically insulating binder specified above, or a thin layer of a thickness of less than 5 microns, which consists of the same or a similar binder as the above specified electrically insulating binders with a content of the finely divided, photoelectric material in a smaller amount than the amount present in the insulating, photoelectric layer, the latter layer being formed on the surface of the insulating, photoelectric layer «As a finely divided, photoelectric material and electrically insulating binder is in particular a combination of a finely divided, photoelectric oadmium sulfide with an average grain size of below 1.5 microns and a hardening or solidifying resin binder with a specific resistance of at least 10 slam. suitable and preferred However, other combinations can also be used, albeit with somewhat reduced effectiveness, which consist of zinc oxide, zinc sulfide, titanium oxide or selenium powder and a thermoplastic resin, thermosetting resin, resin of the catalyst hardening type or resin of the oxide hardening type "

The insulating, photoelectric layer has no, or if at all, only a small one in the dark room electrical conductivity, and has a certain

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electrical conductivity if ed. · with light or another Type of radiation is irradiated «As a method of identification the insulating, photoelectric layer, the following procedure is explained, for example. By the corona discharge in a dark room will generate electrostatic charges on the free surface of the insulating, photoelectric layer, which is formed on an electrically conductive support, applied, the here given electrostatic Charges can be sustained in the dark for a considerably long period of time. The polarity of electrostatic charges depends on the material, which in accordance with the difference in sensitivities, which vary with the rectifier property and polarity should be used »A light sensitive Selenium material is generally positively (plus) charged and a photosensitive zinc oxide material negative (minus). The time for the retention of electrostatic charges on the insulating, photoelectric The layer in the dark room depends on the electrical insulation properties, i.e. the higher the layer, the larger it is Insulating property or ability is generally preferred. The length of time required for the decrease in the surface charges to half the value is generally within several tens to several thousand Seconds. If the insulating, photoelectric layer, which carries electrical charges on its surface, with

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is exposed to suitable light radiation or another suitable radiation, the electrical conductivity becomes increased * and the surface charges are quickly dissipated The decay or damping speed (speed desinpftcens to zero) of the surface charges during the Exposure is generally determined by the length of time required for the charges to decrease to half the value “When exposed to a tungsten lamp of 100 lux, it is about 0.1 to 0.2 seconds for light-sensitive Materials of the selenium type and 2 to 20 seconds for photosensitive materials of the zinc oxide type, whereby / themselves this value changes with the extent of color sensitization «

There are some cases where Joe! Exposure prior to application of charges onto the surface of the photosensitive material, the capacity is decreased to maintain electrostatic charges _t and promoted the fall to zero of the electrostatic charges during the exposure or delayed, "This is a disadvantage of the generally" Vorbelichtungseffekt "is designated and should be avoided in order to obtain a uniformly stable image"

According to the invention, an electrophotographic, photosensitive component with a capacity for retaining electrostatic charges in a dark room and a The speed of the surface charges falling or falling during irradiation or exposure is created, which is cheap and advantageous compared to selenium type photosensitive materials, 9098 38/1185

furthermore, according to the invention, an e lek tr ojipjpto to graphic, created photosensitive material that can be repeatedly applied with a low Yor exposure effect with the formation of consistently stable images »

it also creates the invention an electrophotographic /

photosensitive material which is heat-resistant, provides excellent coating strength and is suitable for repeated use for a long period of time ₉ and is technically and economically advantageously produced at a low cost ,,

Finally, has the manufactured according to the invention insulating, photoelectric layer such an electrical resistance, which is so high in a dark room that only weak electrical conductivity is shown, and during exposure or irradiation with other rays is lowered so that electrical conductivity occurs.

Accordingly, the insulating photoelectric layer can be used in the electrophotographic photosensitive one Member according to the invention not only for electrophotography but also for devices for converting Lieh * or radiation signals or light or radiant energy can be used in electrical signals or energy.

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It is well known that cadmium sulfide is used as a photoelectric Material "is particularly good, but its electrical Resistance in the room as low as 10 - 10 -Π. cm, and is thus far below that for insulating, photoelectric Materials for electrophotography extended values of 10-10-cm · Therefore, it became despite its properties as a photoelectric material are practical not used · A series of studies on cadmium sulfide were directed towards the manufacture of its large single crystal and sintered body, which essentially under the Romans has no unevenness in electrical properties · This has resulted in practical use in photocells in which the characteristics of cadmium sulfide can be effectively exploited. In contrast, there was according to the present invention, the need to reduce the size of the crystals to primary particles or increase their surface area by a number of to form electrical barriers and to increase the electrical resistance in the dark room. Although the correctness the assumption is not yet confirmed, was ee according to the invention in each case for the achievement of an electrophotographic, photosensitive material intended for repeated use. the way successful, in which a finely divided, photoelectric cadmium sulfide with an average grain size of 1.5 microns

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«12 -

or less dispersed in a synthetic resin binder, applying the resulting dispersion to a carrier and forming an insulating, photoelectric Layer from the system of resin and photoelectric ^, fine Powder-containing dispersion dries «Because the electrical conductivity of the insulating, photoelectric layer is determined by the contacts or points of contact between the grains, the mixing ratio must of the binder and the finely divided cadmium sulfide powder be precisely regulated »The optimal mixing ratio of

Other binders and gadmium sulphide powder are within the range of 32 to 42 vol .-% oadmium sulphide powder and 58 to 68 vol .- £ of the binder. It has been found that in a particular case 20 to 60 # of the cadmium sulfide and 80 to 40% of the binder can be used. This mixing ratio depends to a large extent on the type of binder. Synthetic resins with a specific electrical volume resistance of over 10 ./tem are preferably used as binders in order to maintain the electrical resistance of the insulating, photoelectric layer.

As described above, the finely divided photoelectric material and the binder should thus be combined be that the photo and electrical properties of the insulating, photoelectric layer obtained from it is, can be retained in an advantageous manner, with a particularly difficult problem the simultaneous Satisfaction and fulfillment of photo and electrical

'Properties and film strength represents »According to the

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Invention, this difficult problem can be solved by adding an insulating, Iichi electrical layer for the electrophotographic photosensitive component, which consists of two layers, of which the a view of the photo and electrical properties in the maximum amount and the other layer a high one ^ film resistance and especially high wear resistance owns »

The structure of the electrophotographic, photosensitive material according to the invention is explained in more detail with reference to the drawing, in which FIGS. 1 and 2 show schematic sectional images. Referring to Fig. 1, a layer consisting only of the electrically insulating binder which is the same or similar to that used in the insulating photoelectric layer or a layer consisting of the aforesaid binder and the photoelectric powder in a smaller amount is provided formed according to the surface. 2, a layer of the electrically insulating binder which is the same or similar to the binder used in the insulating photoelectric layer containing the photoelectric powder in an amount less than the insulating photoelectric layer is formed on the surface, the content of the photoelectric powder gradually from the insulating photoelectric layer towards

the surface steadily assumes,
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According to Mg ₀ 1, the electrophotographic photosensitive material comprises a support 1 and an electrophotographic photosensitive layer 4 "consisting of an insulating photoelectric layer 2 and a low-content layer 3", the low-content layer 3 is formed only from the binder which is the same or similar to that in the insulating photoelectric layer 2, or from this binder containing a smaller amount of the photoelectric powder than the layer 2. According to Pig and an electrophotographic photosensitive layer V '* i * ^{1 in} which the content of photoelectric powder is steadily changed from the photoelectric insulating part 6 toward the low-content part 7. In each - "' all there is the feature that the Content of photoelectric powder in the vicinity ;? the surface of the electrophotographic photosensitive layer is reduced to a lower amount than that of the inside, thereby improving the wear resistance of the sensitive layer. With the reference number 3 in! 1 and 7 in J ¹ Ig. 2, the surface layers of the photosensitive layer are indicated below, while the reference numerals 2 in ^ 'igo 1 and 6 in fig. 2 denote the inner layer of the light-sensitive layer. The surface layer is inferior to the inner layer in light and electrical properties, and accordingly the former should be possible

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be thin and kept within such a range * that the wear resistance or durability is not lost. that the optimum thickness is 0.5 to 5 microns. A photoelectric powder is preferably incorporated in the surface layer to such an extent that the wear resistance is not impaired, but in certain cases a fine powder having a high wear resistance and low electrical resistance is added to improve the electrical properties. Moreover, it is preferred that the binder for the surface layer and the Innenechicht are the same _t where necessary, similar binders may be used.

The invention is explained in more detail below with the aid of examples

example 1

The dispersed solution was made of a thermosetting acrylic resin (Magicron No. 200, manufactured by Kansai Paint Co.) as the binder and cadmium sulfide as the photoelectric Powder prepared using the following amounts :;

Dadmium sulfide powder 150 g "

Magicron No. 200 clear 125 g (solid «

content 62.5 g)

Magicron No. 200 "thinner-200 (Thinner) medium

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The dispersed solution was applied to a metal tube by the cold spray method and left to stand at room temperature for 10 minutes, whereupon MAgicrpn No. ₀ 200 Klar was applied to it alone. The metal pipe thus coated was subjected to a heat treatment at 150 ^° C. for 30 minutes to cure the resin. The inner layer and the surface layer were 30 microns and 2 microns thick, respectively, after curing. The properties of the resulting electrophotographic photosensitive material or member were as follows. Electrically charged by minus corona discharge gave a surface tension of 800 VaIt; the surface tension sank on exposure to a tungsten lamp of 20 lux for about 3 seconds. no surface layer bearing layer.

Example 2

The. dispersed solution of Example 1 was applied on an aluminum tube by the spray method, "was applied followed by a more dispersed solution having the following composition The thus coated tube was subjected to a heat treatment at 15O ⁰ O for 30 minutes, the photosensitive around a cylindrical electrophotographic Body to form,

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Oadmium sulfide powder 150g

Magicren No. 200 clear 250 g (solids content

125 g)

Magicron No. 200 Thinner 400 ml

The thickness of the coating was in each case: for the inner layer about 50 microns, 2.5 microns, the surface layer, the boundary between the surface layer and the inner layer was not sharp and the content ^of cadmium sulfide _w ^ _r continuously changed "

Example 3

The dispersion of Example 1 was on a - ^ isenrohr applied and then a further dispersion with the following 'composition according to the Spray method applied over it, whereupon the thus treated tube subjected to a heat treatment at 200 0 for 15 minutes was to form a cylindrical electrophotographic photosensitive body " Oadmium sulfide powder 150 g

Magicron No. 500 clear 275 g

Magicron No. 500 thinner 400 ml

Example 4

The dispersion of Example 1 was applied to an aluminum panel and the coated Pla.tte was subjected to heat treatment at 150 ⁰ O for 30 minutes "After cooling, the dispersed solution was prepared according to Example 3

applied over it and the plate covered in this way with a white 909838/1185

subjected to further heat treatment at 200 ° G for 30 minutes, being an electrophotograph! see photosensitive leaf was obtained

Magicron No. 500 is a hardening acrylic resin that is similar to _{Magicron No. 0 200.} In Example 3 and Example 4, the application of the coatings was carried out so that a thickness of about 1.5 microns was obtained, the

photosensitive bodies resulting in high hardness had excellent wear resistance or durability and were similar in appearance to soldering products. In addition, the resistance to moisture, oil, chemicals and solvents was particularly good. »These bodies could be used repeatedly without losing their properties as an insulating, photoelectric layer.

Example 5

An amorphous selenium fine powder having an average grain size below 0.5 microns, which had been previously obtained by reduction of an aqueous solution of selenite at about 5 ⁰ C with sulfur dioxide was in a thermosetting acrylic resin (Magicron No clear prepared ₈₆₀₀ from Kansai Paint Co .) dispersed to form a dispersion «, The amounts given below were used:

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600 clear (D S. (II) G 600 dilution
middle 140 G 75 G Fine powder of amorphous selenium. 120 ml 125 m Magioron Kr 200 180 Magicron Ur.

The dispersion (I) was coated on an aluminum foil, and the dispersion (II) was then coated on the coating surface obtained above. forced) cooled «The resulting electrophotographic photosensitive sheet exhibited good flexibility, high resistance to bending (bond strength) and impact or impact, and was resistant to repeated uses. Under regulation of the coating thicknesses of the inner layer and the surface layer after solidification to 20 microns _e or 1.5 microns, the material was charged by the corona discharge to plus, wherein a surface tension of about Volt was granted. Exposure to a tungsten lamp of 100 lux resulted in a decrease in the surface potential to half that value for 0.4 seconds. The wear resistance was also excellent

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Example 6

A dispersed solution having the composition shown below was applied to an aluminum plate Formation of a photosensitive body applied:

Dispersion (I) dispersion (II)

Silicone coating KS 206 * 48 parts by weight 67 parts by weight cadmium sulfide powder 100 "81" Xylene 200 "250»

* manufactured by Shin-Etsu Chemical Industry

The aluminum plate was first coated with the dispersion (I) and then subjected to a heat treatment at 70 ^° C. for 30 minutes, whereupon the dispersion (II) was applied as a coating and a further heat treatment was carried out at 150 ^° C. for 75 minutes «

Example 7

An iron tube was charged with the dispersed solutions of the following compositions in the order of (i) '(II) and (III) coated by the spray coating method and then subjected to heat treatment at 160 ⁰ C during. Subjected to 20 minutes to obtain a photosensitive tube »

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»-21 -

(I) (H) (HD parts by weight

Cadmium sulfide powder 100 85 80 Amylac No. 2 clear * 42 57 62

Amylac Fr «2 thinner 200 200 200

* A paint base for the coatings that bake or harden at high temperatures Made of butylated melamine resin, non-drying Kijizöl type alkyd resins and epoxy resin by Kansai Paint Co ")

Example 8

An aluminum sheet was coated with diepergierten solutions of the following compositions in the order of (i) and (II), and dried at room temperature for 24 hours, to obtain a -elektrophotographisches light-sensitive material _D instead of an aluminum sheet was a sheet of paper used .

lii) (H)

Zinc Oxide Powder / 130 g ^ 70 g Million No. 1A "Clear 125 g 125 g

Million No. 1A hardener 12.5 g 12.5 g

Million Nr ₀ 1A diluent 200 ml 00 180 ml

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Claims (1)

Claims Electrophotographic, photosensitive material with a support, characterized in that it is an insulating material Inner layer formed of an insulating binder and photoelectric powder, and a has applied over it surface layer, which consists of the same or a similar binder as that used in the insulating photoelectric layer Binder, optionally with a content of dispersed therein photoelectric powder composed of the same powder as in the insulating photoelectric layer exists and is present in a smaller amount than in the insulating photoelectric layer, is formed * J ₀ material according to claim 1, characterized in that the proportions of the photoelectric powder in the insulating, photoelectric layer and in the surface layer are changed discontinuously or continuously, the amount decreasing in the direction of the upper side of the surface layer with continuous change. 3β material according to claim 1 or 2, characterized in that that the insulating binder consists of a curable resin binder 90 9838/1185 4. Material according to e ± * iem of claims 1 "to 3" characterized in that the photoelectric powder consists of a finely divided cadmium sulfide, zinc oxide, zinc sulfide, titanium oxide or selenium powder. 5 «material according to claim 4, characterized in that the photoelectric cadmium sulfide powder has an average Has a grain size of 1.5 microns, 6. Material according to one of claims 1-5 »characterized in that in the insulating, photoelectric layer the binder and the gadmium sulfide powder in a mixing ratio in the range of 32 to 42 vol .- $ cadmium sulfide powder and 58 to 68 vol .- # des Binders are present. 909838/1185 Blank page