JPH01566A - Electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a specific diethyl aromatic compound in its photosensitive layer.

Conventionally, inorganic materials such as selenium, cadmium sulfide, and zinc oxide have been used as photoconductive materials for photoreceptors used in electrophotography. What is the "electrophotographic method" mentioned here?

In general, a photoconductive photoreceptor is first charged in the dark, for example, by corona discharge, and then imagewise exposed to selectively dissipate the charge only in the exposed areas to obtain an electrostatic latent image. This is an image forming method in which images are developed and visualized using electrostatic fine particles (toner) made of colorants such as dyes and pigments and binders such as polymeric substances to form images.

The basic characteristics required of a photoreceptor in such an electrophotographic method are (1) ability to be charged to an appropriate potential in a dark place, (2) less dissipation of charge in a dark place,
(3) The charge can be quickly dissipated by light irradiation.

By the way, it is true that each of the above-mentioned inorganic substances has many advantages, but also various disadvantages.For example, selenium, which is currently widely used, has the above-mentioned (1) to (3). Although the above conditions are fully satisfied, the manufacturing conditions are difficult, the manufacturing cost is high, and there is no flexibility.

It also has drawbacks such as it is difficult to separately fabricate it into a belt shape, and it is sensitive to heat and mechanical shock, so care must be taken when handling it. Cadmium sulfide and zinc oxide are used as photoreceptors by being dispersed in a resin as a binder, but they cannot be used as is because of mechanical drawbacks such as smoothness, hardness, tensile strength, and abrasion resistance. cannot be used.

In recent years, electrophotographic photoreceptors using various organic materials have been proposed in order to eliminate these drawbacks of inorganic materials, and some of them have been put into practical use.

For example, poly-N-vinylcarbazole and 2,4°7-
A photoreceptor consisting of donitrofluoren-9-one (described in U.S. Pat. No. 3,484,237), poly-
Photoreceptor made by sensitizing N-vinylcarbazole with a pyrylium salt dye (described in Japanese Patent Publication No. 48-25658)
, a photoreceptor whose main component is an organic pigment (Japanese Patent Application Laid-Open No. 47-375
43 (described in Japanese Patent Application Laid-open No. 10735), and a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (described in Japanese Patent Application Laid-open No. 10735/1983). Although these photoreceptors have excellent properties and are considered to be of high practical value, considering the various requirements for photoreceptors in electrophotography, it is still difficult to fully meet these requirements. The reality is that we have not been able to obtain anything that satisfies us.

However, all of the photoreceptors mentioned so far differ depending on the purpose or manufacturing method, but generally speaking, good characteristics can be obtained by using excellent photoconductive materials. .

OBJECT It is an object of the present invention to provide a photoreceptor that overcomes the various drawbacks of the conventional photoreceptors mentioned above and fully satisfies the conditions required in electrophotography. Another object of the present invention is to provide an electrophotographic photoreceptor that is easy to manufacture, relatively inexpensive, and has excellent durability.

(2) - One Precept As a result of research and consideration on many photoconductive substances, the inventors have found the following general formula (1)% formula % () [In the above formula, Ar" is substituted or unsubstituted. represents an aromatic hydrocarbon group or a heterocyclic group, A is a substituted or unsubstituted N-substituted rubazolyl group or an unsubstituted aromatic hydrocarbon group or a heterocyclic group,
R1 and R2 represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group] It has been shown that the diethyl aromatic compound represented by I found it. Yet again. It has also been discovered that this diethyl aromatic compound can be used in combination with various materials to create photoreceptors with unexpected effects, as will be apparent from the description below. The present invention was completed based on these findings.

That is, the present invention provides an electrophotographic photoreceptor in which a photosensitive layer is provided on a conductive support.
) is characterized in that it contains a diethyl aromatic compound represented by the following as an active ingredient.

Examples of the aromatic hydrocarbon group for A r 1 and Ar" in the above general formula (1) include substituted or unsubstituted phenylene group, naphthylene group, biphenylene group, anthranylene group, N-substituted rubazole group, etc. Examples of R1 and R2 include a chenylene group, examples of the alkyl group for R1 and R2 include a lower alkyl group, a benzyl group, etc., and examples of the aryl group include a phenyl group.
, R'' include a lower alkyl group, an alkoxy group, a halogen atom, a phenyl group, a cyano group, etc. Ar'' and Ar2 have a substituent such as a lower alkyl group, a lower alkoxy group, or a halogen. You may do so.

The diethyl aromatic compound represented by the general formula (I) used in the present invention is obtained by reacting a phosphonic acid ester compound or a triphenylphosphonium salt compound with an aldehyde compound. It is obtained by reducing a bisstyryl compound synthesized by a so-called modified Wittig reaction or Wittig reaction.

Specific examples of the diethyl aromatic compound represented by the general formula (I) thus obtained are illustrated below.

(Left below) A-CH, CH, -@-C1 (2CH2-A (
T ) ^-CH, CH2-4 lesson CH, CH, -A
(1') (However, -A=-Ar2-N) (Left below is blank space) A-CH, CH, -Ar''-CH, CH2-A
(I)A -CH,CH2-Ar1- CH2CH2-
ARl (where -A=-Ar"-N) The photoreceptor of the present invention contains one or more diethyl aromatic compounds of general formula (1) as described above in the photosensitive layer 2 (2' ,2
', 2'', or 21, but depending on the application of these compounds, they can be used as shown in Figure 1, Figure 2, Figure 3, Figure 4, or Figure 5. Can be done.

The photoreceptor shown in FIG. 1 has a photosensitive layer 2 comprising a diethyl aromatic compound, a sensitizing dye, and a binder (binder resin) on a conductive support 1. The photoreceptor shown in FIG. The diethyl aromatic compound here acts as a photoconductive substance, and the generation and transfer of charge carriers necessary for light attenuation take place via this compound. However, diethyl aromatic compounds have almost no absorption in the visible region of light, so
For the purpose of forming an image using visible light, it is necessary to sensitize by adding a sensitizing dye that absorbs in the visible region.

The photoreceptor shown in FIG. 2 has a photosensitive layer 2' provided on a conductive support 1, in which a charge generation layer 3 is dispersed in a charge transport medium 4 made of a diethyl aromatic compound and a binder. be. The diethyl aromatic compound here together with the binder (or binder and plasticizer) forms the charge transport medium, while the charge generating substance 3 (charge generating substance such as an inorganic or organic pigment) generates the charge carriers. do. In this case, the charge transport medium 4 is mainly responsible for receiving charge carriers generated by the charge generating substance 3 and transporting them. In this photoreceptor, the basic condition is that the absorption wavelength regions of the charge generation layer and the diethyl aromatic compound do not overlap each other, mainly in the visible region. This is because in order to efficiently generate charge carriers in the charge generation material 3, it is necessary to transmit light to the surface of the charge generation material.

The diethyl aromatic compound represented by the general formula (I) has almost no absorption in the visible region, generally absorbs light in the visible region, and when combined with the charge generation layer 3 that generates charge carriers, particularly effectively transports charges. Its characteristic is that it works as a substance.

The photoreceptor in FIG. 3 has a photosensitive layer 2 consisting of a conductive support 1, a charge generation layer 5 mainly composed of a charge generation substance 3, and a charge transport layer 4 containing a diethyl aromatic compound.
# is provided. In this photoreceptor, light transmitted through the charge transport layer 4 reaches the charge generation layer 5, and charge carriers are generated in that region, while the charge transport layer 4 receives charge carriers and transports them. The generation of charge carriers necessary for light attenuation is performed by a charge generation substance 3, and the transport of charge carriers is performed by a charge transport layer 4 (mainly a diethyl aromatic compound acts). This mechanism is similar to the explanation given for the photoreceptor shown in FIG.

The photoreceptor shown in FIG. 4 is obtained by reversing the stacking order of the charge generation layer 5 shown in FIG. 3 and the charge transport layer containing a diethyl aromatic compound, and the mechanism of charge carrier generation and transport is as described above. It can be done in the same way as explained. In this case, in consideration of mechanical strength, a protective layer 6 may be provided on the charge generation layer 5 as shown in FIG.

To actually produce the photoreceptor of the present invention, in the case of the photoreceptor shown in FIG. 1, one or more diethyl aromatic compounds are dissolved in a solution containing a binder, and then added to the solution. The photosensitive layer 2 may be formed by preparing a liquid containing an infectious agent, coating the liquid on the conductive support 1, and drying it.

The thickness of the photosensitive layer 2 is 3 to 50 μm, preferably 5 to 20 μm.
m is appropriate. The amount of the diethyl aromatic compound in the photosensitive layer 2 is 30 to 70% by weight, preferably about 50% by weight, and the amount of the sensitizing dye in the photosensitive layer 2 is 0.1 to 70% by weight.
5% by weight, preferably 0.5 to 3% by weight. As a sensitizer, triarylmethane dyes such as brilliant green, Victoria blue B, methyl violet, crystal violet, acid violet 6B, rhodamine B, rhodamine 6G, rhodamine G extra, eosin S, erythrosin, rose bengal,
Xanthine dyes such as fluorescein, thiazine dyes such as methylene blue, cyanine dyes such as cyanine, 2,6-diphenyl-4-(N,N-dimethylaminophenyl)thiapyrylium verchlorate, benzopyrylium salts (especially Examples include biryllium dyes such as those described in Publication No. 48-25658). Note that these sensitizing agents may be used alone or in combination of two or more.

In addition, in order to produce the photoreceptor shown in FIG. The photosensitive layer 2' may be formed by coating it on the support 1 and drying it.

The thickness of the photosensitive layer 2' is 3 to 50 μm, preferably 5 to 20 μm.
μm is appropriate. The amount of the diethyl aromatic compound in the photosensitive layer 2' is 10 to 95% by weight, preferably 30 to 90% by weight.
% by weight, and the amount of the charge generating substance 3 in the photosensitive layer 2' is 0.1 to 50% by weight.

Preferably it is 1 to 20% by weight. Examples of the charge generating substance 3 include inorganic pigments such as selenium, selenium-tellurium, cadmium sulfide, cadmium-selenium sulfide, and α-silicon; examples of organic pigments include CI Pigment Blue 25 (color index Cl21180) and CI Pigment Red 41 ( CI21200), C.I. Acid Red 52 (CI45100), C.I. Hesic L/2 Do 3 (CI45210), Azo pigment having a carbazole skeleton (described in JP-A-53-95033), Azo pigment having a distyrylbenzene skeleton (described in JP-A-53-133445), an azo pigment having a triphenylamine skeleton (described in JP-A-53-133-132),
347), an azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728),
Azo pigments having an oxadiazole skeleton
12742), an azo pigment having a fluorenone skeleton (described in JP-A No. 54-22834), an azo pigment having a bisstilbene skeleton (described in JP-A-54-17)
733), azo pigments having a distyryloxadiazole skeleton (described in JP-A-54-2129), azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-2129),
Azo pigments such as CI Pigment Blue 16 (CI7410)
0), indigo pigments such as C.I. Butt Brown 5 (CI73410), C.I. Butt Dye (CI73030), Argo Scarlet B (manufactured by Bayer), Indanthrene Scarlet R (manufactured by Bayer), etc. Examples include perylene pigments. Note that these charge generating substances may be used alone or in combination of two or more types.

Furthermore, in order to produce the photoreceptor shown in FIG. 3, a charge-generating substance is vacuum-deposited on a conductive support 1, or fine particles 3 of a charge-generating substance are deposited in a suitable solvent in which a binder is dissolved, if necessary. Apply the dispersion liquid dispersed inside and dry it,
Furthermore, if necessary, the surface is finished by methods such as puff polishing.

The charge generation layer 5 is formed by adjusting the film thickness, and then a solution containing one or more diethyl aromatic compounds and a binder is applied and dried to form the charge transport layer 4. The charge generating material used to form the charge generating layer 5 here is the same as that used in the description of the photosensitive layer 2'.

The thickness of the charge generation layer 5 is 5 μm or less, preferably 2 μm or less, and the thickness of the charge transport layer 4 is suitably 3 to 50 μm, preferably 5 to 20 μm. When the charge generation layer 5 is of a type in which charge generation substance fine particles 3 are dispersed in a binder, the proportion of the charge generation substance fine particles 3 in the charge generation layer 5 is 10 to 95% by weight, preferably 50-90
It is about % by weight. Further, the amount of the diethyl aromatic compound in the charge transport layer 4 is 10 to 95% by weight, preferably 3% by weight.
It is 0 to 90% by weight.

To make the photoreceptor shown in FIG.
A solution of a diethyl aromatic compound and a binder dissolved therein is applied and dried to form a charge transport layer 4. Then, fine particles of a charge generating substance are applied onto the charge transport layer, and if necessary, a binder is applied. The charge generation layer 5 can be formed by applying and drying a dispersion in a solvent by spray coating or the like.The thickness of the charge generation layer or the charge transport layer and the charge contained in these layers. The amount ratio of the generating substance or the charge transporting substance is the same as that explained in FIG. A protective layer 6 is further formed on the charge generation layer 5 of the photoreceptor thus obtained by spray coating or the like with a suitable resin solution, thereby producing the photoreceptor shown in FIG. 5. As the resin used here, the following binders can be used.

In any of these photoconductor productions, the conductive support 1 may be a metal plate or metal foil such as aluminum,
A plastic film coated with a metal such as aluminum, or paper treated with conductivity is used.

In addition, as a binder, polyamide, polyurethane, polyester, epoxy resin, polyketone 1. Condensation resins such as polycarbonate, vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide are used, but any insulating and adhesive resin can be used. Plasticizers are added to the binder if necessary, and such plasticizers include halogenated paraffins, polychlorinated biphenyls,
Examples include dimethylnaphthalene and dibutyl phthalate.

Furthermore, in the photoreceptor obtained as described above, an adhesive layer or a barrier layer can be provided between the conductive support and the photosensitive layer, if necessary. The materials used for these layers include polyamide, nitrocellulose, aluminum oxide, etc., and the film thickness is preferably 1 μm or less.

To make a copy using the photoreceptor of the present invention, the photoreceptor surface is charged and exposed, then developed and, if necessary, transferred to paper or the like. The photoreceptor of the present invention has excellent advantages such as high sensitivity and flexibility.

Examples are shown below. In the following examples, all parts are by weight.

Production example of diethyl aromatic compound 1 2.50 g of 1.4-bis(4-N,N-diphenylaminostyryl)benzene was dissolved in 50 m2 of tetrahydrofuran, 0.25 g of 5% palladium-carbon was added thereto, and the mixture was heated with hydrogen at 19°C. Hydrogenation was carried out in a large shaking hydrogenation apparatus at a pressure of 1 atm. After the hydrogenation was completed, the mixture was filtered with Celite, and tetrahydrofuran was distilled off under reduced pressure to obtain white crystals. This was subjected to column chromatography using silica gel-toluene, and ethanol-toluene.
Recrystallization from a mixed solvent of ethyl acetate yields white needle-like crystals (
2.18 g (yield 86.5%) of compound Nα22) was obtained. The melting point was 162.5-163.5°C.

Elemental analysis value (%) HN Actual value 88.95 6,64 4.
30 infrared absorption spectrum (KBr tablet method) showed that the c-Hffi external bending angle vibration absorption of the 963as-'' transolefin observed in the styryl compound as the starting material disappeared.

Production example of diethyl aromatic compound 2 1.3-bis(4-N,N-diphenylaminostyryl)benzene 3. OOg to tetrahydrofuran 60ya
Dissolve in Q and add 0.60 g of 5% palladium-carbon to this.
was added and hydrogenated at 26° C. and a hydrogen pressure of 1 atm using a large shaking hydrogenator. After the hydrogenation was completed, the mixture was filtered with Celite, and tetrahydrofuran was distilled off under reduced pressure to obtain pale yellow crystals. This was subjected to column chromatography using silica gel as a packing material and toluene/n-hexane as a developing solvent (1/2 volume ratio), and recrystallized from a mixed solvent of ethanol/ethyl acetate to obtain 2.57 g of white needle-shaped crystals (compound Na269). (Yield 85.7%
) was obtained.

The melting point was 119.0-120.0°C.

Elemental analysis value (%) HN Actual value 89,13 6,46 4.
9601-1 in the styryl compound which is the starting material according to the infrared absorption spectrum (KBrBr method) of 50.
It was observed that the absorption based on the C-H out-of-plane bending vibration of the trans-olefin disappeared.

Example 1 76 parts of Diane Blue (CI Pigment Blue 25. Cl21180) as a charge generating substance, 1260 parts of a 2% tetrahydrofuran solution of polyester resin (Vylon 200.@Toyobo II) and 3700 parts of tetrahydrofuran were ground and mixed in a ball mill. The resulting dispersion was applied using a doctor blade onto the aluminum surface of a conductive support made of a polyester base coated with aluminum vapor, and air-dried to form a charge generation layer with a thickness of about 1 μm.

On the other hand, 2 parts of Na24 diethyl aromatic compound and polycarbonate resin (Panlite K 13
After mixing and dissolving 2 parts (manufactured by Denni Co., Ltd.) and 16 parts of tetrahydrofuran to form a solution, this was applied onto the charge generation layer using a doctor blade, and the mixture was heated at 80°C for 2 minutes.
Then, it was dried at 105° C. for 5 minutes to form a charge transport layer with a thickness of about 20 μm, thereby producing a photoreceptor Na 1.

Examples 2 to 27 Photoreceptors Na 2 to 27 were prepared in exactly the same manner as in Example 1, except that the charge generation substance and charge transport substance (diethyl aromatic compound) were replaced with those shown in Table 1 below. .

(Margin below) Table 1 Example 28 A charge generation layer was formed by vacuum evaporating selenium to a thickness of about 1 μm on an aluminum plate having a thickness of about 300 μm. Next, 2 parts of Nα24 diethyl aromatic compound, polyester resin (Polyester Adhesive 490 manufactured by DuPont)
00) Mix 3 parts and 45 parts of tetrahydrofuran,
A charge transport layer forming liquid is prepared by dissolving the liquid, which is applied onto the charge generating layer M (selenium vapor deposited layer) using a doctor blade, air dried, and then dried under reduced pressure to a thickness of approximately 10 mm.
The photoreceptor Nα of the present invention is formed by forming a charge transport layer of μm.
I got 28.

Example 29 The same procedure was carried out except that a perylene pigment was used instead of selenium to form the charge generation layer (however, the thickness was about 0.3 μm), and a diethyl aromatic compound of Nα22 was used instead of NcL24. A photoreceptor Nα29 was prepared in exactly the same manner as in Example 28.

Example 30 A mixture of 1 part of Diane Blue (same as that used in Example 1) and 158 parts of tetrahydrofuran was ground and mixed in a ball mill, and then 12 parts of a diethyl aromatic compound of Nα24 and a polyester resin ( A photosensitive layer forming solution obtained by adding 18 parts of Polyester Adhesive 49000 (manufactured by DuPont) and further mixing was applied onto an aluminum-deposited polyester film using a doctor blade, and dried at 100°C for 30 minutes to form a thick film. A photoreceptor Nα30 of the present invention was prepared by forming a photoreceptor layer having a thickness of approximately 16 μm.

Examples 31 to 57 Example 1 except that the charge generating substance and charge transporting substance (diethyl aromatic compound) were replaced with those shown in Table 2 below.
Photoreceptors Nα31 to Nα57 were prepared in exactly the same manner.

Table 2 Example 58 A photoreceptor Nα58 was obtained in exactly the same manner as in Example 28 except that Compound 269 was used as the charge transporting substance.

Example 59 A photoreceptor Nα59 was obtained in exactly the same manner as in Example 29 except that compound Nα430 was used as the charge transport material.

Example 60 A photoreceptor Nα60 was obtained in exactly the same manner as in Example 30, except that the compound Na269 was used as the charge transport substance.

Example 61 On a polyester film substrate coated with aluminum,
Compound Nα instead of compound &24 as charge transport substance
The same charge transport layer coating solution as in Example 1 was applied with a blade in the same manner as in Example 1, except that No. 269 was used, and then dried to form a charge transport layer having a thickness of about 20 μm. After pulverizing and mixing 13.5 parts of bisazo pigment (P-2), 5.4 parts of polyvinyl butyral (trade name: 1700 parts of ethyl cellosolve was added and mixed with stirring to obtain a charge generation layer coating solution. This coating solution was spray coated onto the above charge transport layer and dried at 100° C. for 10 minutes to form a charge generation layer with a thickness of about 0.2 μm. Furthermore, polyamide resin (product name: CM-80) is applied on top of this charge generation layer.
00, manufactured by Toshi) by spray coating and drying at 120°C for 30 minutes to a thickness of approximately 0.5 cm.
A photoreceptor Nα61 was prepared by forming a protective layer with a thickness of μm.

The photoreceptors Nα1 to Nα61 thus produced were tested using a commercially available electrostatic copying paper tester (5P42 manufactured by KK Kawaguchi Electric Seisakusho).
8 type) to perform a 16 KV or +6 KV (7):10 discharge for 20 seconds to charge it, leave it in a dark place for 20 seconds, and measure the surface potential Vpo (volts) at that time.
Then, the tungsten lamp light was applied to the surface of the photoreceptor with an illuminance of 2.
Calculate the time (seconds) until the surface potential becomes 1/2 of Vpo by irradiating it so that it becomes 0 lux, and calculate the exposure amount E1-2 (
lux seconds) was calculated. The results are shown in Table-2.

In addition, after each of the photoreceptors described above is charged using a commercially available electrophotographic copying machine, light is irradiated through the original image to form an electrostatic latent image, and the image is developed using a dry developer. When the image (toner image) was electrostatically transferred onto plain paper and fixed, a clear transferred image was obtained. A similarly clear transferred image was obtained when a wet developer was used as the developer.

(Leaving space below) Table 3 Table 3 (Continued) Table 3 (Continued) The photoreceptor of the present invention not only has excellent photosensitive properties, but also has high strength against heat and mechanical impact. Moreover, it can be manufactured at low cost.

[Brief explanation of drawings]

1, 2, 3, 4, and 5 are cross-sectional views enlarged in the thickness direction of the electrophotographic photoreceptor according to the present invention. 1... Conductive support 2. 2', 2', 2", 2"... Photosensitive layer 3... Charge generating substance 4... Charge transport medium or charge transport layer 5... Charge generation Layer 6...protective layer

Claims (1)

[Claims] 1. Compound A-CH_2CH_2-Ar^1-CH_2CH_2- represented by the following general formula (I) on a conductive support
A (I) [In the above formula, Ar^1 represents a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group, A is a substituted or unsubstituted N-substituted carbazolyl group, or ▲ mathematical formula, chemical formula, table, etc. There is▼(However, Ar^2
is a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group, R^1 and R^2 are a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group] 1. A photoreceptor for electrophotography, characterized in that it has a photosensitive layer containing one of these as an active ingredient.