JPS6255140B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a photoconductive element and a method of manufacturing an electrophotographic light-sensitive material using such a photoconductive element. Electrophotography involves uniformly charging an electrostatic charge onto a layer of photoconductive material, applying an imagewise exposure to discharge the electrostatic charge in the exposed areas, and then producing an image of the residual charge (an electrostatic latent image). ) is developed with colored particles (toner) having the opposite polarity to record a visible image, and is a well-known method. Conventionally, photoconductive substances used in electrophotographic materials include:
Known materials include inorganic substances such as amorphous selenium and compound semiconductors, organic polymers such as polyvinyl carbazole, organic dyes and pigments, and materials using these as sensitizers in combination with various organic compounds.
Of these, amorphous selenium is most frequently used. Electrophotographic materials using amorphous selenium are typically produced by vapor depositing selenium onto a conductive support. However, with this method, continuous production is difficult and production costs are high. Further, the vapor-deposited amorphous selenium layer has the disadvantage that it tends to crystallize during manufacture or use, and therefore its properties as a photosensitive material tend to deteriorate. In order to eliminate these drawbacks, a method has been proposed in which a layer in which selenium particles are dispersed is provided on a conductive support by a coating method. i.e. UK patent
No. 1,506,929 describes a photoconductor in which selenium element crystals are mechanically crushed and dispersed in a polymer capable of transporting charge carriers, and U.S. Pat. No. 3,787,208 describes an amorphous selenium solid. A photoconductor is described in which a photoconductor is mechanically pulverized in liquid nitrogen and dispersed in a polymer. However, it is difficult to produce a photoconductive layer in which fine selenium particles are uniformly dispersed by such mechanical pulverization. On the other hand, a method of manufacturing a dispersed layer of fine selenium element particles using light irradiation has also been proposed. That is, as described in U.S. Pat. No. 3,994,791, a layer of an organic selenium compound dispersed in an insulating polymer (e.g., poly-N-vinylcarbazole) capable of transporting charge carriers is formed on a conductive support. It is applied on top using a coating method, and is uniformly irradiated with light.
This is a method of decomposing an organic selenium compound to produce a layer in which elemental selenium is dispersed in a polymer. However, this method has disadvantages, such as that organic selenium compounds are generally unstable and expensive, and that organic selenium compounds, their decomposition products, or synthetic compounds in the process of synthesis are often toxic or have a bad odor. Furthermore, when an organic selenium compound is photodecomposed in a polymer, the absorption of light is nonuniform, so the closer it is to the surface of the layer, the more it is decomposed.As a result, a photoconductor layer with selenium elements uniformly dispersed throughout the layer is formed. Difficult to manufacture. Another major limitation is that the polymer is limited to insulating polymers with charge carrier transport ability. Further, US Pat. No. 4,115,115 describes a method for producing a layer in which selenium element is dispersed in a polymer by reacting an organic selenium compound and dibenzoyl peroxide in a polymer. However, like the above-mentioned method, this method has the disadvantage of using an organic selenium compound, and furthermore, dibenzoyl peroxide is explosive and must be handled with great care. Therefore, the object of the present invention is to produce colloidal selenium by a chemical method rather than a vapor deposition method or a photodecomposition method, and by a method that eliminates the various drawbacks of the method using the above-mentioned organic selenium compounds. It is an object of the present invention to provide a means for making photoconductive elements in which elemental particles are dispersed in a polymer. Another object of the present invention is to provide a method for producing electrophotographic materials using the photoconductive elements obtained thereby and having higher photosensitivity using less selenium than those using vapor-deposited amorphous selenium. That's true. Other objects of the invention will become apparent from the description below. Basically, the object of the present invention is to obtain a photoconductive element in which elemental selenium is finely dispersed in a polymer by chemically reducing an inorganic selenium compound in the presence of an insulating polymer. achieved by. That is, according to the present invention, by reducing an inorganic selenium compound by chemical means in a liquid phase or solid phase containing an insulating binder polymer to liberate selenium element, fine colloidal A photoconductive element is obtained in which selenium particles are dispersed in a polymer. Here, the selenium particles have the function of generating charge carriers upon irradiation with light. The photoconductive element thus obtained is used as a light guiding conversion element for photovoltaic cells, electrophotographic photosensitive materials, and the like. According to one embodiment of the present invention, the photoconductive element comprises (a) an inorganic selenium compound and (b) an insulating polymer dissolved or dispersed in a solvent capable of dissolving at least (b) and reduced. It is produced by finely precipitating and dispersing the selenium element liberated from (a) into (b). The method for manufacturing the photoconductive element according to the invention will now be described in detail. The inorganic selenium compound used in the method for producing a photoconductive element according to the present invention may be any inorganic selenium compound as long as it can liberate elemental selenium through a ring atom. Among these inorganic selenium compounds, those that are solid at room temperature, relatively stable, and soluble in solvents, particularly organic solvents, are useful. Examples of inorganic selenium compounds having such characteristics include selenium dioxide, selenite, selenium oxybromide (), selenium tetrachloride, and selenium tetrabromide.
Among these compounds, selenium dioxide and selenite are superior in that they are resistant to hydrolysis, have no bad odor, and are easy to handle, and are particularly preferably used in the present invention. The insulating polymer used in the method for producing a photoconductive element according to the present invention acts as a protective colloid or binder for finely dispersing the selenium element liberated from the inorganic selenium compound by reduction. As an insulating binder polymer,
Many synthetic, semi-synthetic and natural polymeric dielectric materials having sufficient molecular weight to form a film (approximately 10,000 or greater) are suitable;
Those that do not significantly decompose even when heated for about 10 minutes at temperatures up to about 250°C are useful. It may or may not have electrical activity, ie the ability to transport charge carriers. Polymers that are generally used as insulating binders in electrophotographic light-sensitive materials are used. Specific examples of suitable insulating binder polymers include polycarbonate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymers,
Vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, polystyrene, poly-α-methylstyrene, polymethyl methacrylate, polymethyl acrylate, polybutyl acrylate, polyvinyl butyral, polyvinyl formal, polyvinyl pyrrolidone, polyvinyl alcohol, polyacrylamide, poly Acrylonitrile, diacetyl cellulose, triacetyl cellulose, cellulose acetate phthalate, cellulose acetate butyrate, ethyl cellulose, cyanoethyl cellulose, poly-
N-vinylcarbazole, polyvinylpyrene, polyester, polyamide, styrene-butadiene copolymer, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, vinylidene chloride-vinyl acetate copolymer, chlorinated polyethylene, chlorinated polypropylene, phenol-formaldehyde resin, etc. be. Note that in the case of a copolymer, the monomer content ratio is not particularly limited. Among these insulating binder polymers, particularly preferred in terms of their high charge carrier generation efficiency are polymethyl methacrylate, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polycarbonate, and the like. The inorganic selenium compound and the insulating polymer are dissolved or dispersed in a solvent that can dissolve at least the insulating polymer. The solvent used here can be selected from a wide variety of solvents as long as it can dissolve at least the binder polymer used. Considering the handling of the photoconductive element solution or dispersion prepared and the removal of the solvent, a solvent having a boiling point of about 30 to about 200°C is preferred. Suitable solvents include, for example, methanol,
Alcohols such as ethanol and isopropanol,
Aliphatic ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, ethers such as dimethyl sulfoxide, tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, methyl acetate, and acetic acid. Esters such as ethyl, chloroform, methylene chloride, ethylene dichloride, carbon tetrachloride, halogenated hydrocarbons such as trichlorethylene, benzene, toluene,
Examples include hydrocarbons such as xylene and ligroin, and water. These solvents may be used alone or in combination of two or more. Among these, solvents that also dissolve the inorganic selenium compound are particularly preferred. There are no particular limitations on the proportions of each component in the solvent or dispersion for photoconductive elements according to the present invention. Generally, however, the inorganic selenium compound is present in an amount of from about 10 ^-4 to about 10 ^-2 moles, especially 5 moles per gram of insulating polymer.
It is preferable to use the ^insulating polymer in an amount of about ^0.005 to about
It is preferred to use 0.5 g, especially 0.01 to 0.1 g. A photoconductive element solution or dispersion prepared by appropriately mixing each component such as an inorganic selenium compound, an insulating polymer, and a solvent can be molded into any shape depending on the purpose and use to form a photoconductive element. It can be done. For example, a layered photoconductive element is formed by coating on a suitable support and removing the solvent (drying). Drying can be carried out at any temperature, generally from room temperature (approximately 10 to 30 degrees Celsius) to approximately 250 degrees Celsius.
The temperature range up to The precipitation of elemental selenium by reduction of the inorganic selenium compound proceeds in the state of a solution or dispersion or during drying after molding. Therefore, if it is desired to promote the precipitation of selenium element, it is preferable to perform drying under heating conditions of about 50° C. or higher. In addition, when processed at a temperature of approximately 80℃ or higher,
Changes in properties presumed to be due to the formation of crystalline selenium were observed. That is, it has been found that the photosensitivity of an electrophotographic material having a photoconductive element subjected to such heat treatment is significantly improved. Therefore, good results are often obtained when drying is carried out in the temperature range of about 50 to about 200°C. An appropriate temperature can be selected by considering the type of binder polymer and solvent used. Note that it is also possible to perform drying at a relatively low temperature and then heat it again at a higher temperature to promote or complete the precipitation of the selenium element. The drying time varies widely depending on the drying temperature, but is usually about 5
minutes to about 5 hours is appropriate. According to the present invention, precipitation of elemental selenium occurs to some extent even without the addition of a particular reducing agent, and photoconductive elements may be obtained with considerable charge carrier generation efficiency. This is thought to be due to the fact that even though the inorganic selenium compound alone is stable, reduction of the inorganic selenium compound occurs due to interaction with the insulating binder polymer and/or solvent, especially during heat drying. In particular, if the insulating polymers or solvents used are themselves reducing, or even if they are not themselves reducing, some reducing substance is generated during the manufacturing process of the photoconductive element, and even if the insulating polymers or solvents used are When a reducing substance is present as an impurity in the polymer or solvent, the reduction of the inorganic selenium compound proceeds. for example,
Ketone solvents such as acetone often contain reducing substances such as aldehydes. However, in order to efficiently and sufficiently precipitate the selenium element, it is preferable to use a reducing agent intentionally. Thus, according to one preferred embodiment of the invention, the photoconductive element comprises (a) an inorganic selenium compound;
(b) An insulating polymer and (c) a reducing agent are dissolved or dispersed in a solvent that can dissolve at least (b), and the selenium element liberated from (a) by reduction is finely dispersed into (b). Manufactured by precipitation and dispersion. The inorganic selenium compound, insulating polymer, solvent, manufacturing conditions, etc. used here are basically the same as those described above. Now, the ring-forming agent used in the present invention may be any substance that can reduce the inorganic selenium compound to liberate the selenium element, and a wide range of organic or inorganic ring-forming substances are effective.
As the reducing agent, a single compound may be used, or two or more compounds may be used as a mixture in an appropriate quantitative ratio. In general, the reducing power of two or more compounds as a whole is not necessarily the simple sum of the reducing powers when each is used alone, and often shows a greater reducing power, and this is due to superaddition. This is also known as superadditivity. Therefore, even if a compound does not have sufficient reducing power alone, it may be sufficiently usable in a mixed system. A useful reducing agent (a single compound or a mixture of two or more compounds) used in the present invention can be easily selected by the following method. Selection of reducing agent Test method: 10 mg of selenium dioxide and twice the molar amount of the reducing agent to be tested (if the reducing agent is tested as a mixture of two or more compounds, the total number of moles of them is mixed with 10 mg of selenium dioxide) (2 times the molar amount of 20%) were separately dissolved in 1ml each of a solvent selected from ethanol, N,N-dimethylformamide, or tetrahydrofuran in which selenium dioxide and a reducing agent are soluble, and then this The two solutions are mixed uniformly in a test tube, sealed, and placed in a hot bath at 100°C ± 5°C. If orange to red coloring due to precipitation of elemental selenium is observed in the solution or on the vessel wall within 30 minutes thereafter, the reducing agent (or mixture of reducing agents) is a reducing agent useful in the present invention. . The above selection test method is one way to determine the lower limit of the reducing agent's ability; if the reducing power of the reducing agent is below the lower limit of this test, the amount of selenium element precipitated will decrease, and therefore the photoconductivity will decrease. In an electrophotographic light-sensitive material using a reactive element, its photosensitivity is lower than when a reducing agent above this lower limit is used.
Therefore, this lower limit is not strict, and if a reducing agent slightly below this limit is used, the electrophotographic material produced using it will not show no photosensitivity at all, but will continue to Only the light sensitivity is reduced. Therefore, the above limits are only a guideline for providing electrophotographic materials with desirable and sufficient photosensitivity, and depending on the purpose of use,
It is possible to use it outside the above limits. Useful reducing agents can be selected by the above test method, so it is not necessary to specify a specific type of compound, but in general, reducing compounds used as developing agents for silver halide photographic light-sensitive materials, for example, Appropriate. Examples of such reducing compounds are, for example, CEK Mees and TH James,
“The Theory of the Photographic Process”
(3rd edition, 1966, Macmillan Company)
Described in Chapter 13 of Some examples of compounds used as reducing agents in the present invention include aromatic compounds such as benzene, naphthalene, and anthracene substituted with at least one hydroxyl group and/or amino group or substituted amino group. Organic compounds such as group hydrocarbons (e.g., hydroquinone derivatives, aminophenol derivatives, aniline derivatives, P-phenylenediamine derivatives, etc.), hydrazine derivatives, ascorbic acid derivatives, pyrazolone and pyrazolidone derivatives, urea derivatives, oxalates, aldehydes, etc. and hydrochloric acids of metals in low valence states (e.g. iron (), tin (),
Salts such as titanium (), chromium (), etc. Some specific examples of reducing agents that have characteristics exceeding the lower limit as a result of the above-mentioned reducing agent selection test and are therefore suitably used in the present invention include trimethylhydroquinone, tetramethylhydroquinone, 2,
5-di-tert-butylhydroquinone, methoxyhydroquinone, (1,1-dimethyl-3,3-
dimethylbutyl)hydroquinone, 2-(α,α
-dimethylbenzyl)-5-tert-butylhydroquinone, 2-(α,α-dimethylbenzyl)-5
-(1,1-dimethyl-3,3-dimethylbutyl)hydroquinone, 2,5-di(1,1-dimethylbutyl)hydroquinone, 2,5-dimethylhydroquinone, P-N-benzylaminophenol, P-N -Methylaminophenol, 2-phenylhydroquinone, N-ethyl-N-hydroxyethyl-2-methyl-paraphenylenediamine, N,N-dimethylparaphenylenediamine,
N,N,N',N'-tetramethylparaphenylenediamine, acetohydrazine, O-aminobenzoylhydrazine, acetylphenylhydrazine,
Salicilloylhydrazine, 1-methyl-1-phenylhydrazine, L-ascorbic acid, L-ascorbyl monopalmitate, L-ascorbyl monostearate, 3-pyrazolidone, 1-phenyl-3-pyrazolidone, 1-phenyl- 4-Methyl-3-pyrazolidone, 1-P-tolyl-4-hydroxymethyl-4-methyl-3-pyrazolidone, thiourea, dimethylolthiourea, tetramethylthiourea, thiouracil, 4-methoxy-1
-naphthol, 4-ethoxy-1-naphthol,
4-aminodiphenylamine, N, N, N',
N'-tetramethyl-P,P'-diaminodiphenylamine, iron oxalate (), tin chloride (), and the like. For reference, specific examples of selection tests for some representative compounds among the reducing agents exemplified above are shown below. Reference Example 10 mg of selenium dioxide was placed in a test tube with an outer diameter of approximately 15 mm, and 1 ml of N,N-dimethylformamide was added and shaken to completely dissolve the selenium dioxide. Next, take twice the molar amount of 10 mg of selenium dioxide of each of the reducing agents listed in Table 1 below into another similar test tube,
1 ml of N,N-dimethylformamide was added to dissolve the reducing agent. Mix the two solutions in a test tube,
After shaking well and sealing, it was immersed in a boiling water bath and allowed to stand for 30 minutes. As shown in Table 1, red to black precipitation of elemental selenium was observed on the inner wall of the test tube and/or in the solution in all cases.

[Table] The amount of reducing agent used (in the case of a mixture, the total amount) varies depending on the strength of its reducing ability, etc., but in general, it is approximately
It is preferred to use from 0.1 to about 10 mol, especially from 1 to 5 mol. Even in the method of manufacturing a photoconductive element that intentionally uses a reducing agent, other factors such as the inorganic selenium compound, insulating polymer, solvent, and manufacturing conditions are
This system is basically the same as the system described above in which no reducing agent is intentionally used. However, some modifications, such as those described below, often yield favorable results. That is, the solvent used can be appropriately selected from the above-mentioned solvents. Among these, those that dissolve not only the insulating binder polymer but also at least one of an inorganic selenium compound and a reducing agent, especially both at the same time, are preferred. Such solvents are
Depending on the type of inorganic selenium compound, reducing agent, and binder polymer, a solvent can be selected from the above-mentioned solvents by suitably conducting a dissolution test. By way of example, ethanol, acetone, methyl ethyl ketone, N,N-dimethylformamide, tetrahydrofuran, etc. are most useful as common solvents. Even in a system using a reducing agent, if the reducing power of the reducing agent is relatively small, sufficient precipitation of selenium element may not occur in the solution or dispersion. In such a case, it is preferable to carry out the drying at a temperature of about 50° C. or higher to promote and complete the precipitation of the selenium element. On the other hand, if a reducing agent with relatively high reducing power is used, most of the inorganic selenium compound in the solution or dispersion may be reduced and elemental selenium may be precipitated. Drying conditions can therefore vary considerably depending on the type of ingredients used. In any case, drying should be carried out at a temperature and time such that at least the reduction of the inorganic selenium compound is completed. In addition, even if precipitation of selenium element has already occurred in the solution or dispersion, in the present invention, since the binder polymer coexists, the selenium element will not rapidly aggregate or precipitate.
A photoconductive element is produced that is dispersed as fine colloidal particles. According to the method for producing a photoconductive element of the present invention, elemental selenium is released into a binder polymer, compared to the method described in the above-mentioned US Pat. It has the advantage that it is possible to obtain a layer in which selenium is uniformly dispersed, and that it can be manufactured using an inorganic selenium compound which is more stable, safer and cheaper than an organic selenium compound. Furthermore, binder polymers are not limited to polymers with charge carrier transport ability.
Another great advantage is that electrically inactive insulating polymers can be used. Photoconductive elements according to the invention are useful as photoconductive layers in electrophotographic materials. That is, as mentioned earlier
A solution or dispersion for photoconductive elements in which (a) an inorganic selenium compound, (b) an insulating polymer, and optionally (c) a reducing agent are dissolved or dispersed in a solvent that can dissolve at least (b). The selenium element dispersed layer obtained by coating and drying the liquid is used in electrophotographic photosensitive materials.
A layer that generates charge carriers by light irradiation (Carrier
Generation Layer (hereinafter abbreviated as CGL). If satisfactory electrophotographic properties cannot be obtained with such a selenium element dispersed layer (CGL) alone, charge carriers generated in the CGL by light irradiation may be efficiently injected and transported to form a conductive support or photoconductive layer. layer capable of discharging to the surface of the carrier, i.e. the carrier transport layer.
(hereinafter abbreviated as CTL) in combination with the selenium element dispersed layer according to the present invention. In this case, it is preferable to provide the CGL and CTL adjacent to each other to form a photoconductive layer having a laminated (or multilayer) structure of two layers. The CGL and CTL may be stacked in any order on the conductive support. On the other hand, when a single photoconductive layer is formed by mixing a CGL component and a CTL component, its sensitivity is significantly inferior to that of a photoconductive layer having a laminated structure. To provide a CGL comprising a selenium element dispersed layer, which is a photoconductive element according to the present invention, the photoconductive element solution or dispersion described above is applied to a conductive support or a CGL provided on a conductive support. Apply on top of
Just dry it. Coating can be carried out using methods known to those skilled in the art, such as rod coaters, roller coaters, curtain coaters, dip coaters, spinner coaters, whirler coaters, and the like.
The appropriate coating temperature is usually about 0 to about 80°C, more preferably 20 to 50°C. For drying, the conditions described above for the photoconductive element can be applied. For drying purposes only, the temperature is usually about 200℃ from room temperature.
C., particularly in the temperature range of 50 to 100.degree. C. for about 5 minutes to about 5 hours, particularly preferably 10 minutes to 2 hours. The coating amount should be determined so that the CGL film thickness after drying is approximately 0.1 to approximately 10
It is preferable to adjust the thickness to be in the range of .mu.m, more preferably in the range of 0.5 to 5 .mu.m. When providing the CGL according to the present invention, if the above-mentioned photoconductive element solution or dispersion intentionally containing a reducing agent is used as the coating liquid for the CGL, a sufficient amount of selenium element can be deposited. has been achieved,
An electrophotographic material with excellent photosensitivity can be obtained. The conductive support used in the present invention may be one that is generally used in electrophotographic light-sensitive materials, such as various metal plates or foils; metals such as aluminum, nickel, chromium, silver, gold, copper, palladium, or oxidized materials. Suitable examples include a plastic film on which a semiconductor such as indium or tin dioxide is vacuum-deposited; or a layer in which a conductive substance such as cuprous iodide or carbon black is dispersed in a binder polymer is provided on the plastic film. Next, in the electrophotographic light-sensitive material according to the present invention,
Explain CTL. In the present invention, generally known CTLs can be used. For example, photoconductive polymers such as poly-N-vinylcarbazole (US3037861), polyvinylpyrene (Brit1506929), and charge transfer complexes of these and trinitrofluorenone (Japanese Patent Publication No. 50-10496),
It may also be a layer in which a low-molecular organic charge carrier transport material (sometimes referred to as an organic photoconductive material or an organic electroactive material) is dispersed in an insulating polymer. Many compounds are known as charge carrier transport substances used in the latter case, and are suitably used in the present invention. For example, triarylmethanes (US3542547), triarylalkanes and tetraarylmethanes (US3542544), diarylalkanes (US3615402), N,N-dibenzylaniline derivatives (US3767393), aniline derivatives (Brit1316994), distyryl-containing Aromatic compounds (US3873311), polyaryl hydrocarbons (US4045220), tritolylamine (US3732554), arylamines (US3240597,
Same 3180730, Same 3567450, Same 3658520, Same
3615414), tetraphenyldiaminobiphenyls (US4047948, 4047949), 4-diarylamino substituted chalcones (US3615414), trinitrofluorenones (US3615414), pyrazolines (US3837851, 3180729), oxadiazoles ( US3189447), thiadiazoles (Brit1004929), 5-aminothiadiazoles (US3161505), triazoles (US3112197,
3122435, Brit951106, Brit952906), imidazolones (US3097095), oxazoles (Brit874634), thiazoles (Brit1008631), imidazoles (Brit938434), bisimidazolidines (US3127266), pyrazines (Brit1004461) ,1,2, 4-triazines (US3130046), arylideneoxazolones (US3072479), benzothiazoles, benzimidazoles, benzoxazoles (Brit895001,
1008632), quinazolines (US3139339), benzofurans (US3140946), acridine and phenazines (US3224516), carbazoles (US3206306), ethylene derivatives (US3246983),
Examples include benzylideneanilines (Brit836151), polyenes (Brit964874), aminostilbenes (US3158475), and arylketones (Brit1008633), and at least one of these is used. Note that here, US stands for US patent and Brit stands for British patent. Among these substances that can be used for CTL, some examples of substances that are particularly useful for the electrophotographic light-sensitive material of the present invention are listed below. 1,3,5-triphenylpyrazoline, 1-phenyl-3-(P-dimethylaminostyryl)-5
-(P-dimethylaminophenyl)-pyrazoline,
1-phenyl-3-(P-methoxystyryl)-5
Pyrazolines such as -(P-methoxyphenyl)-pyrazoline, 1-phenyl-3-styryl-5-phenylpyrazoline, 1-phenyl-3-phenyl-5-(P-dimethylaminophenyl)-pyrazoline ; Triaryl or diarylmethanes such as leucomalachite green, leuco crystal violet, tetrabase; 4,4'-benzylidenebis(N,N-diethyl-m-toluidine), 2',2''-dimethyl-4 , 4′,4″-tris(dimethylamino)triphenylmethane, etc.; 2,2-bis(4-N,N-dimethylaminophenyl)propane, 1 ,1-bis(4-N,
Diarylalkane compounds described in US Pat. No. 3,615,402 such as N-dimethylaminophenyl) cyclohexane; bis(4-dimethylamino)-1,
Tetraarylmethane or triarylalkane compounds described in US Pat. No. 3,542,544 such as 1,1-triphenylethane, 4-dimethylaminotetraphenylmethane; 4-N,N-dimethylaminophenyl-4'-N, N-dimethylaminostyryl ketone, 1-(P-N,N-dimethylaminobenzoyl)-4-(P-N,N-dimethylaminophenyl)-butadiene-1,3, di(P-N,N- dimethylaminostyryl)ketone, di(P-N,N
Chalcone and diaryl ketones such as -diethylaminophenyl)ketone; P-N,N-dimethylaminostilbene, P-P'-N,N,N',
Aminated hydrocarbons such as N'-tetramethyldiaminostilbene; low molecular weight photoconductive (charge carrier transport) materials such as trinitrofluorenone; and poly-N-vinylcarbazole, poly-N-vinylcarbazole and trinitrofluorenone; These include polymeric photoconductive substances such as charge transfer complexes of fluorenone (molar ratio of carbazole ring to trinitrofluorenone of 5/1 to 1/2). When using a polymeric photoconductive substance as a CTL, it is dissolved in a solvent and used as a conductive support or
Apply on top of CGL and let dry. The ratio of polymeric photoconductive material to solvent is approximately 0.5 to 1 ml of solvent.
Approximately 0.005 g, particularly 0.1-0.02 g is preferred. Also
When using a low molecular weight charge carrier transport material for CTL, it is dissolved in a common solvent together with an insulating polymer, coated on a conductive support or CGL, and dried. In that case, the proportion of charge carrier transport material (or total in the case of a mixture) to insulating polymer is from about 10 ^-4 to about 5 x 10 ^-3 mol per gram of polymer;
In particular, 3×10 ^-4 to 3×10 ^-3 mol is preferable, and the ratio of the insulating polymer to the solvent is as follows:
About 0.5 to about 0.005 g, especially 0.1 to 0.01 g is preferred.
As the insulating polymer, the above-mentioned insulating polymers used for manufacturing photoconductive elements are preferably used. Among these insulating polymers, the present invention
When used in CTLs, polycarbonate, polymethyl methacrylate, polyvinyl butyral, and the like are particularly preferred in terms of their high charge carrier transport efficiency and high mechanical strength. Further, the solvent is appropriately selected from among the solvents used in the photoconductive surface solution or dispersion described above. The coating amount is approximately 1 to 100 mm thick after drying.
It is preferable to adjust the thickness to be in the range of μm, more preferably in the range of 5 to 30 μm. Apply and dry as described above.
This can be done in the same way as for CGL. The charge carrier transport materials used in CTLs are themselves generally photoconductive materials, but most are only photosensitive to ultraviolet light and either have no absorption in the visible light region or have no absorption in the visible light region. It only shows absorption in a relatively short wavelength range. So on top of CGL
Even if a CTL is provided, there is no problem because most of the actinic light, that is, visible light required to generate charge carriers in the CGL passes through the CTL. Regardless of the stacking order of CTLs and CGLs on the support, visible light is primarily absorbed by the CGLs, and charge carriers are also generated exclusively within the CGLs. A structure in which CTL is simply provided on a conductive support without using CGL exhibits little or no photosensitivity to visible light. In this way, an electrophotographic light-sensitive material is produced in which a photoconductive layer consisting of a laminated layer of CGL and CTL is provided on a conductive support. By the way, we have discovered that when such an electrophotographic light-sensitive material is heat-treated at a temperature of about 80° C. or higher, the photosensitivity of the electrophotographic light-sensitive material can be dramatically improved, that is, about 10 times or more. This improvement in photosensitivity is mainly due to the fact that the colloidal selenium element (mainly considered to be amorphous) formed in CGL by the end of drying is caused by heat treatment. It is presumed that this is based on rearrangement, aggregation, or crystallization, especially crystallization. That is, before heat treatment, the photoconductive layer generally exhibits a yellow to orange color, but upon heat treatment, the color gradually disappears and changes to gray to dark red. Note that these considerations regarding the improvement of photosensitivity are mere speculations and do not limit the present invention. It should be noted that the improvement in photosensitivity due to this heat treatment will only occur if the temperature of the drying process after application of CGL is high enough.
It can happen to a certain extent. In addition, during the heat treatment process,
It is possible that the reduction is not completed by the time the drying of the CGL is completed, and the remaining unreacted inorganic selenium compound is further reduced and contributes to a certain degree of improvement in photosensitivity. The appropriate temperature for the heat treatment is about 80 to about 250℃, preferably 100 to 200℃, and the heat treatment time is about 10 to 250℃.
The time period is from seconds to about 1 hour, more preferably from 30 seconds to 10 minutes. If the heat treatment temperature is low, the improvement in photosensitivity will be small; on the other hand, if the heat treatment temperature is too high, the selenium element will aggregate too much, and the increase in photosensitivity will not be as high.
Heat treatment can be accomplished by applying heat-rich radiation, such as infrared radiation, to a uniformly heated hot plate, or by applying heat to a heated inert (i.e., does not dissolve or react with the photoconductive layer) This can be carried out by a method such as immersion in a liquid medium (for example, silicone oil, etc.). In addition, in the method for producing an electrophotographic light-sensitive material of the present invention, the heat treatment is performed mainly on CGL and CTL.
It is recommended that the process be carried out after a laminate consisting of the above is provided on a conductive support. On the other hand, even if heat treatment is performed at the stage where CGL is provided on the conductive support and then CTL is laminated, the photosensitivity increases considerably compared to the case where no heat treatment is performed at all. However, it has been found that the photosensitivity of the final electrophotographic light-sensitive material is much higher when the laminate is heat-treated after being formed. This is thought to be because, as mentioned above, the sensitivity improvement due to heat treatment is mainly based on the crystallization of the selenium element, and the crystallization proceeds efficiently in a state where air is blocked. That is,
When CTL is stacked on top of CGL, CTL blocks air; on the other hand, when CGL is stacked on top of CTL, air can penetrate near the surface of CGL, but
Air is blocked near the interface with CTL, and selenium crystallization progresses sufficiently. If on a conductive support
If heating is performed at the stage where the CGL is provided, crystallization will proceed in areas close to the support, but crystallization in the surface layer will be inhibited by air. i.e. CTL
It is inferred that formation of a sufficient amount of crystalline selenium particles at the interface between CGL and CGL is necessary in order to achieve high photosensitivity. However, this is just speculation and does not limit the invention. The electrophotographic light-sensitive material of the present invention produced in this manner does not undergo ordinary copying, that is, a copying method that allows reuse of light-sensitive materials such as a toner image transfer method or an electrostatic latent image transfer method, and does not undergo reuse. It can also be used in conjunction with the method of fixing permanent toner images onto photosensitive materials. That is, in the electrophotographic photosensitive material of the present invention, with the conductive layer of the conductive support electrically grounded, the surface of the photoconductive layer is exposed to a corotron or scorotron in the dark to a surface potential of about 200 to about 1000 V. It is uniformly charged using a charging device such as the above. Next, it is exposed imagewise from the surface direction (if the conductive support is transparent to actinic light, through the support from the surface direction or from the rear direction). The surface electrostatic charge is discharged at the exposed area and an electrostatic latent image is formed. Next, the electrostatic latent image may be developed with toner, transferred to an image-receiving sheet and fixed, or fixed directly onto a photosensitive material to form a permanent image, or the electrostatic latent image is transferred to an image-receiving sheet and then applied with toner. Development and fixing may be performed. These image forming methods are described, for example, by John W.Weigl, Angew.Chem.
(International Edition), 16 374 (1977). The mechanism of formation of an electrostatic latent image is thought to be as follows. Charge carriers, possibly within or on the surface of the colloidal selenium element within the CGL upon exposure to light,
That is, pairs of electrons and holes are formed. These charge carriers are transported and discharged to the surface of the conductive support or photoconductive layer, respectively, based on the charges on the surface and the potential gradient applied between the supports, thus eliminating the static charge. However, this photodischarge process differs depending on the structure of the photoconductive layer and the polarity of the electrostatic charge on the surface. That is, when CGL is adjacent to a conductive support and an electrostatic charge is charged on the surface of CTL, if the electrostatic charge is negative,
Among the charge carriers generated in the CGL, electrons are transported to the conductive support and discharged, while holes are injected into the CTL and transported within the CTL to reach the surface and neutralize the surface static charge. . Conversely, if the electrostatic charge is positive, holes are transported to the conductive support and discharged, while electrons are injected into the CTL and discharged.
Transported within CTL and neutralized on the surface. accordingly
It is desirable that the charge carrier transport substance in the CTL be P-type in the former case and n-type in the latter case because the photodischarge rate and therefore the photosensitivity are higher. In addition, if the configuration of the photoconductive layer is reversed, that is, the CTL is adjacent to the conductive support and the surface of the CGL is charged with an electrostatic charge,
This is the opposite of the above. That is, in the case of negative charge,
It is preferable to use an n-type charge carrier transport substance in the CTL, or a p-type substance in the case of a positive charge. Among the charge carrier transport substances mentioned above, trinitrofluoronolenone and its charge transfer complex with poly-N-vinylcarbazole are n-type and suitable for transporting electrons, and most of the others are p-type, that is, effective for transporting holes. It is something. Especially transport efficiency (mobility) or
P-type cells often have good injection efficiency of charge carriers from CGL to CTL. When a CTL is formed using a P-type charge carrier transporting substance, the most preferred form of the electrophotographic material of the present invention is that when the surface is positively charged, the CTL is placed adjacent to a conductive support. When a CGL is used and is negatively charged, the structure is such that the CGL is placed adjacent to a conductive support, and almost the same photosensitivity can be obtained regardless of the polarity of the electrostatic charge. Furthermore, n
When forming a CTL using a type of charge carrier transport material, high photosensitivity can be obtained when the polarity of the charged charge is reversed. The main effects obtained by the present invention are as follows. First, an electrophotographic material with high photosensitivity can be obtained using only a small amount of selenium. for example,
Approximately the same photosensitivity can be obtained with a fraction of the amount of selenium used in the case of selenium vapor deposition. Second, the transmitted optical density of the photosensitive layer is quite low;
When a transparent conductive support is used, an electrophotographic light-sensitive material that is nearly transparent can be obtained. Thirdly, the electrophotographic photosensitive material is manufactured entirely through the coating process without using a vapor deposition process, and therefore can be manufactured continuously in large quantities and is expected to reduce manufacturing costs. . Fourthly, the photodischarge characteristics of the electrophotographic light-sensitive material obtained by the present invention are extremely excellent in the following points.
That is, if the type of CTL and the thickness of CGL are appropriately selected, fatigue of the photosensitive material due to photodischarge is extremely small, and therefore it can be used repeatedly in a short period of time. Further, since the residual potential is small and a sufficient amount of exposure can be applied, almost complete discharge can be achieved, so that copies with less fog can be obtained. The present invention also includes the following embodiments. 1. (a) An inorganic selenium compound and (b) an insulating polymer are dissolved or dispersed in a solvent that can dissolve at least (b), and the selenium element liberated from (a) by reduction is added to (b). 3. A method according to claim 1 or 2, comprising dispersing. 2. Dissolve or disperse (a) an inorganic selenium compound, (b) an insulating polymer, and c-reducing agent in a solvent that can dissolve at least (b), and remove the selenium element liberated from (a) by reduction. b) A method as claimed in claim 1 or 2, comprising dispersing in. 3. The method according to aspect 2, wherein the reducing agent has a reducing power specified in the selection test method described in the text. 4. Applying a liquid material obtained by dissolving or dispersing (a) an inorganic selenium compound and (b) an insulating polymer in a solvent that can dissolve at least (b) onto a substrate, and removing the solvent. The method according to aspect 1. 5 (a) Applying a liquid material obtained by dissolving or dispersing an inorganic selenium compound, b an insulating polymer, and c a reducing agent in a solvent that can dissolve at least b onto a substrate, and removing the solvent. The method according to aspect 2. 6. A method according to embodiment 4 or 5, comprising removing the solvent at a temperature from room temperature to about 250°C. 7 Applying a liquid material obtained by dissolving or dispersing (a) an inorganic selenium compound and (b) an insulating polymer in a solvent that can dissolve at least (b) onto a conductive support, and removing the solvent. A method according to claim 2, comprising: 8 A liquid material obtained by dissolving or dispersing (a) an inorganic selenium compound, (b) an insulating polymer, and (c) a reducing agent in a solvent that can dissolve at least b is applied onto a conductive support. 3. A method according to claim 2, which comprises removing the solvent. 9. The method of embodiment 7 or 8, wherein the solvent is removed at a temperature from room temperature to about 250°C. 10 In a method for producing an electrophotographic light-sensitive material having a charge carrier generation layer and a charge carrier transport layer on a conductive support, an inorganic selenium compound is reduced in the presence of an insulating polymer so that elemental selenium is dispersed in the polymer. A method comprising the step of forming a charge carrier generation layer comprising: 11. The method according to embodiment 10, wherein the charge carrier generation layer and the charge carrier transport layer are laminated in this order on the conductive support. 12. The method according to embodiment 10, wherein the charge carrier transport layer and the charge carrier generation layer are laminated in this order on the conductive support. 13 (a) An inorganic selenium compound and (b) an insulating polymer are dissolved or dispersed in a solvent that can dissolve at least (b), and the selenium element liberated from (a) by reduction is added to (b). Mode consisting of dispersing
10 to 12. 14 (a) Inorganic selenium compound, (b) insulating polymer, and (c) reducing agent are dissolved or dispersed in a solvent that can dissolve at least (b), and selenium element liberated from (a) by reduction. 13. A method according to embodiments 10 to 12, comprising dispersing in (b). 15. The method according to aspect 14, wherein the reducing agent has a reducing power specified in the selection test method described in the text. 16 Applying a liquid material obtained by dissolving or dispersing (a) an inorganic selenium compound and (b) an insulating polymer in a solvent that can dissolve at least (b) onto a conductive support or charge carrier transport layer. and removing the solvent. 17 A liquid material obtained by dissolving or dispersing (a) an inorganic selenium compound, (b) an insulating polymer, and (c) a reducing agent in a solvent that can dissolve at least (b) is used as a conductive support or a 15. The method according to embodiment 14, comprising applying onto the carrier transport layer and removing the solvent. 18. A method according to embodiment 16 or 17, comprising removing the solvent at a temperature from room temperature to about 250°C. 19. The method of embodiment 18, wherein the method is carried out at a temperature of about 50°C or higher. 20. The method of embodiment 19, which is carried out at a temperature of about 80°C or higher. 21 Remove the solvent at a temperature of 50 to 100 °C and further
Embodiment 18 including a step of heat treatment at a temperature of ℃ or higher
The method described in. 22 The method according to aspect 21, wherein the heat treatment is performed at a temperature of 100 to 200°C. 23 Claims 1 and 2, aspects 1 to 23
23. A photoconductive element or electrophotographic material produced by the method described in 22. The present invention will be explained in more detail below using Examples. However, the present invention is in no way limited to these examples. In the following examples, the photoconductive properties of the electrophotographic photosensitive materials were measured using an electrostatic charging tester Model SP-428 manufactured by Kawaguchi Electric. That is, the conductive support of the photosensitive material is grounded, the surface of the photoconductive layer is charged by corona discharge, and the light from the tungsten lamp (color temperature 2856〓) is attenuated by a diaphragm and an ND filter, and the upper surface of the photoconductive layer is more exposed,
The attenuation of the surface potential due to light, ie, the rate of photodischarge, was measured. From this result, the initial photodischarge rate, i.e. (dV/dt) _O /I・d (where, V is the surface potential (unit: V), t: time (unit: second), I: illuminance (unit: lux),
d is the thickness of the photoconductive layer (unit: μm), E〓 is the exposure energy required to discharge the surface potential to 1/2 of the initial potential V _O (unit: lux・sec), and V _R is the potential due to exposure. The so-called residual potential (unit: V), at which the decrease in voltage settles down to a substantially constant value, was determined. The illuminance was 0.1lux. Example 1 45 mg of selenium dioxide and 200 mg of polymethyl methacrylate (average molecular weight approximately 50,000) were added to 5 g of N,N-dimethylformamide and stirred for 5 hours to completely dissolve and form a colorless solution. Apply this solution to an aluminum vapor-deposited polyester film (trade name "Metal Me", manufactured by Toray) using a coating stick, and apply it for 60 minutes.
CGL was formed by drying for 1 hour under hot air blowing at ℃. The dry film thickness of CGL was approximately 1.5 μm, and its color was pale yellow. Next, 35 mg of 1-phenyl-3-(P-methoxystyryl)-5-(P-methoxyphenyl)pyrazoline (charge carrier transport material) and polycarbonate resin (trade name "Iupilon C-2000", average molecular weight: approx. 24000 (manufactured by Mitsubishi Gas Chemical) was dissolved in 1 g of chloroform, applied onto the above CGL using a coating stick, and dried for 1 hour under hot air blowing at 60°C.
A CTL was provided, thus providing a two-layer photoconductive layer on a conductive support. The dry film thickness of the entire two layers was approximately 10 μm. When the thus obtained electrophotographic light-sensitive material was heat-treated by closely contacting the support side on a hot plate at 150° C. for 5 minutes, the color of the photoconductive layer changed to pale yellow-gray. The initial photodischarge rate was 0.3. (V _O =-500V). In addition, when the same procedure was carried out except that CGL was not provided, almost no photodischarge was observed (initial photodischarge rate was 0.05 or less, V _O = -500V), and the same procedure was carried out except that selenium dioxide was not added. No photodischarge was observed when the test was carried out. (V _O =-500V). From the above, it can be seen that the selenium element-containing photoconductive element according to the present invention functions as a photoconductive layer of an electrophotographic photosensitive material. Examples 2 to 9 A solution of selenium dioxide and polymethyl methacrylate dissolved in N,N-dimethylformamide was prepared in the same manner as in Example 1, and the following second solution was added to this solution.
Add 8 x 10 ^-4 mol (twice the molar amount of 45 mg of selenium dioxide) of each of the reducing agents listed in the table, stir, mix uniformly, and immediately coat the aluminum-deposited polyester film (as in Example 1) with a coating rod. (same as used) and dried for 1 hour under hot air blowing at 60°C to form CGL. The color of the coating solution varied depending on the type of reducing agent, ranging from red to pale yellow, and the color of the CGL after drying was red to yellow. The dry film thickness of CGL was approximately 1.5 μm. Thereafter, a CTL was provided in the same manner as in Example 1, and heat treatment was performed. The color of the photoconductive layer after heat treatment was gray to dark red. The photoconductive properties of the obtained electrophotographic photosensitive material are shown in Table 2.

[Table] When charging and exposure were repeated 10 times in succession, initial photodischarge rate and E〓 values were always obtained. That is, no electrical fatigue was observed. Further, the electrophotographic photosensitive material produced in Example 6 was charged to a surface potential of -500V using a corotron, and then passed through a transparent positive original using a tungsten lamp (illuminance on the original surface was about 5 lux). When exposed for a second and immediately subjected to cascade development using positively charged toner, a clear positive image was obtained. Example 10 The same procedure as in Example 6 was carried out except that 52 mg of selenite was used instead of 45 mg of selenium dioxide. The initial photodischarge rate is 3, E = 9, and V _R is 100.
(V _O =-500V). Examples 11 to 17 In Example 6, instead of 200 mg of polymethyl methacrylate as the binder polymer for CGL, 200 mg each of the polymers shown in Table 3 below were used, and as the charge carrier transport material, 1-phenyl-3-
The same procedure was carried out except that 37 mg of 4,4'-benzylidenebis(N,N-diethyl-m-toluidine) was used instead of 35 mg of (P-methoxystyryl)-5-(P-methoxyphenyl)pyrazoline. . The results obtained are shown in Table 3 (V _O =-500V).

[Table] Examples 18 to 26 In Example 6, 1 was used as the charge carrier transport substance.
-Phenyl-3-(P-methoxystyryl)-5-
Instead of (P-methoxyphenyl)pyrazoline,
The same procedure was followed except that each of the compounds shown in Table 4 below was used in an amount of 1.6 x 10 ^-3 mol per gram of polycarbonate resin. The results obtained are shown in Table 4.

[Table] Examples 27 to 28 The same procedure as in Example 6 was carried out except that the solution shown in Table 5 below was applied as the CTL coating liquid. The results obtained are shown in Table 5.

[Table] Examples 29 to 30 In Example 6, the following 6th film was used instead of the aluminum vapor-deposited polyester film as the conductive support.
The test was carried out in exactly the same manner except that the films shown on the front (both were almost transparent) were used. The results shown in Table 6 were obtained (V _O =-500V).

[Table] Examples 31 to 34 Example 6 was carried out in exactly the same manner except that the amount of selenium dioxide was changed as shown in Table 7 below (Example 33 is the same as Example 6) .
The results obtained are shown in Table 7 (V _O =-500V).

[Table] Examples 35 to 38 Example 6 was carried out in exactly the same manner except that the amount of trimethylhydroquinone was changed as shown in Table 8 below (However, Example 37 is the same as Example 6. ). The results obtained are shown in Table 8 (V _O
= -500V).

[Table] Examples 39 to 42 The same procedure as in Example 6 was carried out except that the CGL coating thickness was changed to the value shown in Table 9 below (Example 40 was the same as Example 6). The results obtained are shown in Table 9 (V _O =-500V).

[Table] Example 43 Example 6 was carried out in exactly the same manner except that the order of application of CGL and CTL was reversed. Initial potential (V
_O ) is set to +500V, the initial photodischarge rate is
15, E〓 was 1.4, and V _R was 50. Example 44 45 mg of selenium dioxide, 0.4 g of polycarbonate resin (same as used for CTL in Example 1) and 4,4'-benzylidene bis(N,N-diethyl-
280 mg of m-toluidine) was dissolved in 5 g of N,N-dimethylformamide, then 145 mg of trimethylhydroquinone was added and dissolved, and immediately an aluminum-deposited polyester film (Example 1
(same as that used in )) and dried for 1 hour under hot air blowing at 60°C to form a photoconductive layer. The photoconductive layer was deep red in color and had a film thickness of 8 μm. This was heat treated in the same manner as in Example 1. The initial photodischarge rate was 0.7 (V _O =-350V (saturation potential)). Example 45 The same procedure as in Example 6 was carried out except that the electrophotographic material in which CGL and CTL were laminated was not subjected to heat treatment. The color of the photoconductive layer was yellow-orange. Initial photodischarge rate is 0.8, E〓 is 15, V _R
was 50 (V _O =-500V). Example 46 In Example 6, instead of laminating CGL and CTL and then heat-treating, CGL was applied and dried, and then the support side was placed in close contact with a hot plate at 150°C for 5 minutes and heat-treated. Then, the same procedure as in Example 6 was carried out except that CTL was applied and dried. The color (yellow-orange) of CGL hardly changed due to the heat treatment of CGL. The initial photodischarge rate was 3, E〓 was 7, and V _R was 50 (V _O =-
500V). Example 47 Polymethyl methacrylate (average molecular weight: approx.
50000) was dissolved in 5 g of acetone and then 45 mg of selenium dioxide was dissolved to make an orange solution. This was applied onto an aluminum vapor-deposited polyester film (same as that used in Example 1) using a coating rod without adding a reducing agent, and heated under hot air blowing at 60°C.
After drying for a while, a CGL was applied. The CGL color was orange and the film thickness was about 1.3 μm. Then 1-phenyl-
3-(P-methoxystyryl)-5-(P-methoxyphenyl)pyrazoline (charge carrier transport substance) 35
mg and 45 mg of polycarbonate resin (same as that used in Example 1) were dissolved in 1 g of chloroform,
It was coated onto the above CGL using a coating rod and dried for 1 hour under hot air blowing at 60°C to form a CTL, thus providing a two-layered photoconductive layer on the conductive support. The dry film thickness of the entire two layers was approximately 10 μm.
The initial photodischarge rate of the electrophotographic light-sensitive material thus obtained was 0.4 (V _O =-500V). Example 48 The electrophotographic light-sensitive material obtained in Example 47 was heat-treated by bringing its support side into close contact with a hot plate at 150° C. for 5 minutes. The color of the photoconductive layer after treatment was yellow-gray. Initial photodischarge rate is 7, E〓 is 3, V _R
was 30 (V _O =-500V).

Claims (1)

[Scope of Claims] 1. A method for producing a photoconductive element in which elemental selenium is dispersed in an insulating polymer, the method comprising reducing an inorganic selenium compound in the presence of an insulating polymer. 2. In a method for producing an electrophotographic photosensitive material having a photoconductive layer on a conductive support, an inorganic selenium compound is reduced in the presence of an insulating polymer to form a photoconductive layer in which senone elements are dispersed in the polymer. A method comprising the step of forming.