JPS6019151A - Composite type electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To form a composite type electrophotographic sensitive body sufficiently sensitive to the wavelength region of beams of a semiconductor laser, and superior in resolution and durability by using an electrostatic charge generating layer contg. metal-free phthalocyanine and a charge transfer layer contg. a specified resin. CONSTITUTION:An electrophotographic sensitive body is obtained by laminating on a conductive substrate a charge generating layer contg. (A) a kind of metal- free phthalocyanine selected from tau, tau', eta, and eta' types on a conductive substrate in a thickness of 0.1-3mum, and a 10-30mum thick charge transfer layer composed of a 1/2-1/5weight ratio mixture of (B) a charge transfer compd. represented by formula I (Y is one of formulae II-V; Z is O or S; n is 0, 1, or 2; and R3, R4 are each <4C alkyl), and a resin having repeating units, each represented by formula VI, VII in which R1, R2 are each <=8C alkylene, (cyclo) alkylidene, or allylene.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a composite electrophotographic photoreceptor having high sensitivity in a long wavelength region, which is formed by forming a charge generation layer and a charge transport layer on a conductive support. In particular, the present invention relates to a composite electrophotographic photoreceptor having high resolution and outstanding durability.

[Background of the invention]

An electrophotographic photoreceptor has an inorganic or organic photoconductor layer provided on a conductive support, and in the Seiko photocopier that uses such a photoreceptor, the surface of the photoreceptor is first corona charged. A post-imagewise exposure is performed to create an electrostatic latent image, and then toner is attached to the electrostatic latent image to create a toner powder image, which is transferred to paper or the like to perform copying.

Organic photoconductors generally have lower photosensitivity than inorganic photoconductors, so various sensitization methods have been devised, but the most effective method is to attach a photoreceptor to a charge generation layer that generates charges when irradiated with light. This is to form a groove with a charge transport layer that efficiently transports the charges generated in the charge generation layer. Such a compound m
Electrophotographic photoreceptors generally use monoazo dyes as charge-generating substances.

Organic materials such as disazo dyes, squaric acid dyes, quino-7-anine pigments, metal-free or metal phthalo/anine pigments, or inorganic materials such as tellurium-arsenic-selenium pigments are used, and the charge transport material is poly-N-vinyl. Carbazole, Shidrazoge compound, Hirazoline compound, Oxadiazole compound + F-linitrofluorenone, various nitro- and /ano-substituted compounds are used to form a conductive support either alone or in a dispersed or dissolved state in a resin. It has been used in layers on the body.

Incidentally, in recent years, a method has been devised as a type of high-speed printer that uses a laser as a light source and performs printing using the Nariko photo method. In particular, when a semiconductor laser is used as a light source, the light source section can be made very small, making it possible to make the printer more compact and also to significantly reduce power consumption. However, since the oscillation wavelength of a semiconductor laser is usually a long wavelength of 770 nm or more, the sensitivity of the conventional electrophotographic photoreceptor described above is insufficient, and the resolution required to obtain clear images and the need for repeated use are limited. Safety of various electrophotographic properties (ltl)
There were also various problems with the durability.

[Purpose of the invention]

An object of the present invention is to provide a composite electrophotographic photoreceptor that has sufficient sensitivity even in the oscillation wavelength range of a semiconductor laser, and particularly has excellent resolution and durability.

[Summary of the invention]

The composite electrophotographic photoreceptor of the present invention uses τ-type metal-free phthalo/anine as a charge-generating substance and an oxazole compound as a charge-transporting substance, and in particular, the charge-transporting substance and resin component of the charge-transporting layer have a weight ratio of It is characterized in that it is used at a blending ratio of 1/2 to i15.

Generally, the wavelength range to which a photoreceptor is sensitive depends on the absorption wavelength range of the charge-generating material, as long as the charge-transporting layer used does not interfere with the light absorbed by the charge-generating material. Many studies have been conducted on long-wavelength absorbing charge-generating materials, such as Se.
, CdS, etc., a method has been found to increase the sensitivity of the sensitizer in the long wavelength range, but this method does not have sufficient environmental resistance against temperature and humidity, and there are also problems in terms of toxicity. . Among organic photoconducting materials, various phthalocyanine compounds are known to have good sensitivity in relatively long wavelength ranges, and the present inventors have found that among them, τ-type, τ′-type, η-type, η-type
'-type gold metal phthalonanine τ-type metal-free phthalocyanine, which exhibits high sensitivity in the long wavelength range, is defined as follows. −
That is, the Bragg angle (2θ±0.2 degrees) is 7. Gold, 9
．． It has a strong X-ray diffraction pattern at 2.16.8.17.4°20.4 and 20.9. In particular, the infrared absorption spectrum is 751±2o between 700 and 7Gθm-1.
The four absorption bands with the strongest n-' are 1320 to 1340.
cm-', two absorption bands of approximately the same intensity, 328
It is desirable to have a characteristic absorption at 8±3 cm-'.

τ′ type gold metal phthalocyanine ring defined as follows.

be done. That is, 1,54 of C11K4-/l'J+
Bragg angle (20±0.2 degrees) for one person's X-ray
is 7.5°9.1. 16.8. 17.3. 20.
3. 20.8. It is made of a new metal-free phthalonanine crystal polymorph having strong X-ray diffraction patterns of 21.4 and 27.4. In particular, two absorption bands of approximately the same intensity between 1320 and 1340 cm-' in the infrared region are observed at 3297±3Cy++.
-' is desirable.

η quasi-focal metal phthalocyanine is defined as follows. That is, metal-free phthalocyanine loo part by weight, metal-free phthalocyanine having a substituent on the benzene nucleus, a hephthalonanine nitrogen isomer or metal phthalocyanine which may have a substituent on the benzene nucleus, or one or more types of metal phthalocyanine. The mixture crystal with 50 parts by weight or less of the mixture has an infrared absorption spectrum of 753±1 c between 700 and 760 cm-'.
The four absorption bands with the strongest m-' are 1320 to 1340.
cm-', two absorption bands of approximately the same intensity, 328
It has a characteristic absorption at 5±5cn+-'.

According to the study of the present inventor, l-type gold metal phthalocyanine 9.
Those with X-ray diffraction patterns showing strong peaks at 2.16.8, 17.4 and 28.5, and those with X-ray diffraction patterns showing strong peaks at 7.6.9.2°1
Examples include those having an X-ray diffraction pattern showing strong peaks at 6.8.17.4.21.5 and 27.5.

η′ type metal phthalocyanine/ is defined as follows.

That is, a mixture of 7,100 parts by weight of thermometallic phthalo-7ani, metal-free phthalonanine having a substituent on the benzene nucleus, a phthalonanine nitrogen isomer or metal phthalocyanine which may have a substituent on the benzene nucleus, or a mixture of two or more of them. It is a mixture crystal with 50 parts by weight or less, and the infrared absorption spectrum has four absorption bands with the strongest 753±1 line-1 between 700 and 760 cm-'. 3297±
This is a novel metal-free phthalonanine crystal polymorph having a characteristic absorption of 5on-'. According to the inventor's study, η
' type metal phthalocyanine, especially Bragg angle (2θ 10.2 degrees) is 7.5, 9.1, 16.8 degrees 17.3, 2
Those with X@ diffraction patterns showing strong peaks at 0.3, 20.8, 21.4 and 27.4, and those with ? ,5,9.1,
16.8, 17.3, 20.3, 20.8°21.4,
X showing strong peaks at 22.1, 27.4 and 28.5
A material having a line diffraction pattern is desirable.

In addition, all of the τ type, τ' type, η type, and η' type metal-free phthalonanine have a maximum photosensitive wavelength range of 790 to 810 nm.
It is in the range of m.

The τ type and τ' type gold metal phthalo/anine according to the present invention are prepared in the following manner. J-, that is, 50 to 180 tons of α-type gold phthalocyanine, preferably 60 to 130C
f-form τ by milling with stirring or mechanical strain for a time sufficient to convert the crystals at a temperature of
A gold-free partial phthalocyanine having a typical crystalline form is produced.

The α-type phthalocyanine used in the present invention is a “phthalonanine compound” by Moser and Tokes (M□ser
and Thomas “pHthalocyanin”
For example, metal-free phthalocyanines include metal phthalocyanines that can be demetalized with acids such as sulfuric acid, such as lithium phthalocyanine, sodium phthalocyanine, and calcium phthalocyanine. Phthalocyanines, those made directly from phthalodinitriles, aminoiminoindolenine or alcoquiniminoisoindolenine, etc., are used by acid treatment of phthalocyanine, phthalocyanine, etc. The metal-free phthalocyanine obtained by the already well-known method is preferably dissolved in sulfuric acid at 5C or less or made into a sulfate salt, and then poured into water or ice water and reprecipitated or hydrolyzed to obtain α-type free phthalocyanine. Metal phthalonanine is obtained.

At this time, if an inorganic pigment dissolved or dispersed in sulfuric acid or a reprecipitation solution is used, an α-type metal-free phthalocyanine containing an inorganic pigment can be obtained. The inorganic pigment may be a water-insoluble powder that can be used as a coloring filler, such as titanium white, zinc white carbon, calcium carbonate, etc., and can be used in the form of a powder in a variety of ways.

Examples include gold powder, alumina, iron oxide powder, and kaolin.

The α-type metal-free phthalonanine containing this inorganic pigment is much easier to grind and can be easily made into fine particles when it is made into a pigment than one that does not contain this inorganic pigment, and is effective in saving labor and energy. ``The α-type phthalo/anine treated in this manner is preferably used in a dry state, but a water paste form can also be used. The medium used for stirring and kneading may be those normally used for pigment dispersion, emulsification, etc., such as glass peas, steel beads, alumina balls, and flint stones. However, distributed media is not necessarily required. As the grinding aid, those commonly used as grinding aids for pigments may be used, and examples of the grinding aid include common salt, sodium bicarbonate, and sulfur salt. However, a grinding aid with is also not necessarily required.

If a solvent is required during stirring, mixing, and grinding, stirring,
It may be liquid at the temperature during kneading, such as alcoholic solvents, such as glycerin, ethylene glycol, diethylene glycol or polyethylene glycol solvents, seronlube solvents such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, and ketones. It is preferable to select one or more types from the group of solvents such as ester-based solvents and ester-ketone-based solvents.

Typical devices used in the crystal transition process include general stirring devices, homomixers,
There are dispersers, agitators, stirrers or niegu, Banbury mixers, ball mills, sand mills, attritors, etc.

The temperature range in the crystal transition step of the present invention is 50 to 1so
t:, preferably within a temperature range of 60 to 130C. It is also effective to use crystal nuclei as in the usual crystal transition process.

α-type phthalonanine and be/ze/anine used in producing η-type and η′-type gold metal phthalo/anine according to the present invention.
Metal-free phthalocyanine having a substituent on the nucleus, or a siphthalodianine nitrogen isomer or metal phthalocyanine having a substituent on the benzene nucleus is described in the above-mentioned "phthalocyanine compound j" by Moser and Torts.
r andThomes” pl+thalocya
For example, α-type metal-free phthalocyanine can be obtained by the same formulation as described above, and it contains other inorganic pigments. Also, as a phthalo/anine nitrogen isoconstruct,
There are various porphins, such as copper tetraviridinoborphyrane, which has one or more of the benzene nuclei of phthalo-7anine replaced with a quinoline nucleus, and metal phthalo/anines such as copper, nickel, cobalt, and zinc. , tin, aluminum and the like.

Substituents include amino groups, nitro groups, alkyl groups, alkoxy groups, cyano groups, mercapto groups, halogen atoms, and sulfonic acid groups, carboxylic acid groups or their metal salts, ammonium salts, amine salts, etc. can be exemplified as a relatively simple example. Furthermore, a fullkylene group, a sulfonyl group, a carbonyl group,
Various substituents can be introduced via imino groups, etc., and these are those known as anti-aggregation agents or crystal conversion inhibitors in the technical field of phthalocyanine pigments (for example, US Pat. No. 3,973,981, No. 4,088).
507) or unknown ones. Known methods for introducing each substituent will be omitted. In addition, things that are not publicly known are described as reference examples in the examples.

In the present invention, the mixing ratio of the α-type metal-free phthalocyanine and the metal-free phthalocyanine having 14 substituents on the benzene nucleus, or the phthalonanine nitrogen isoform or metal phthalocyanine which may have a substituent on the benzene nucleus is 100.
It may be 150 (weight ratio) or more, but preferably 10
The weight ratio is 0/30 to 10010.1 (weight ratio). If the ratio exceeds this ratio, the resulting η-type and η′′ phthalocyanines tend to bleed, reducing their suitability as pigments.

In the present invention, mixing in the above-mentioned ratio may be done by simply mixing or by stirring the mixture thus mixed, which may be done before acid pasting the α-type metal-free phthalocyanine. Alternatively, the milling method may be one normally used for dispersing, emulsifying, or mixing pigments, and examples of dispersion media for stirring and kneading include glass beads, snar beads, alumina balls, and flint stones, but the dispersion media is not necessarily do not need.

The grinding aid, the solvent during kneading, the materials used twice in the crystal transition step, and the equipment are the same as those for the τ type and τ' type gold metal phthalo/anine field pieces described above.

The temperature range in the η-type and η'-type gold metal phthalo/anine crystal transition step is 30 to 220C, preferably 60 to 1
Perform within a temperature range of 30C. At higher temperatures, it is easy to transform to the β type, and at lower temperatures, it takes time to transform to the η and η' types. It is also an effective method to use crystal nuclei as in the usual crystal transition process.

Incidentally, a charge generating substance generates ttm due to light passing through the charge transport layer, and the generated charges must be efficiently injected into the charge transport layer by an electric field. Therefore, the charge-generating material must be formed on the conductive support to have appropriate thickness and adhesion. Specifically, the τ-type metal-free phthalocyanine must be uniformly dispersed and used as necessary. It is formed by applying an organic solvent in which a resin component is dissolved onto a conductive support and drying it. In this case, various thermoplastic and thermosetting resins can be used as the resin component, but care must be taken to prevent the charge-generating scales from swelling, peeling, or eluting when applying the charge transport coating. In order to obtain a photoreceptor with good electrophotographic properties, phenolic resin and unsaturated polyester resin are used.

Acrylic resin, urethane resin 7 epoxy resin or/
It is preferable to use a thermosetting resin such as Ricone 1 resin.

On the other hand, fluctuations in the resolution of the photoreceptor, resolution during repeated use, and various electrophotographic properties are mainly affected by the surface physical properties of the charge transport layer, the corona ions of the charge transport material and resin components during repeated use, and the stability against light. Gender has a big influence.

The present inventors conducted various studies on these characteristics of photoreceptors, and found that a compound of the following structural formula and 几4 [wherein Y is at least one heterocyclic group selected from the group consisting of and (
However, Z represents 0 or S, and the heteojJj group is! ! ), n represents 0.1 or 2, and R3 and 几. is an alkyl group having 3 or less carbon atoms. ] A compound with a resin having a repeating unit represented by the general formula ren group, alkylidene group, arylene group, or cycloalkylidene group)
It has been found that a photoreceptor with high resolution and excellent durability can be obtained by forming 4.

Conventionally, charge transport materials used in charge transport layers with large ionization potentials (Ip) do not allow smooth carrier transport, making it impossible to obtain highly sensitive photoreceptors. Since the Ip is small at 6.66 V or less, high sensitivity can be obtained.

In addition, the resin component having 9 repeating units represented by the above general formula is various polycarbonate resins, polyarylate resins, and modified resins thereof obtained by reacting various bisphenols with phosgene, and has excellent transparency. A resin with surface hardness, heat resistance, etc.

In the composite electrophotographic photoreceptor of the present invention, a charge transport layer may be first formed on a conductive support, and a charge generation layer may be formed thereon, but in particular, in order to improve the durability of the photoreceptor, It is desirable to first form a charge generation layer on a conductive support and then form a charge transport layer thereon. In that case, the mixing ratio of the above-mentioned compound used for the charge transport layer and one finger of wood is 1/2 by weight.
It is desirable to have a mixture in the range of 1/5 to 1/5, preferably 1/3 to 1/4. Conventionally, in order to provide a photoreceptor with high sensitivity, a charge transporting material was generally mixed in the charge transporting layer in an amount of about 50% by weight. However, as a result of detailed studies by the present inventors, we found that although it is true that the photosensitivity of the photoreceptor is good when the proportion of the charge transport material in the charge transport layer is high, it has a negative effect on the charging characteristics and resolution of the photoreceptor. Furthermore, it has become clear that electrophotographic properties (particularly a decrease in resolution) are significantly affected when the photoreceptor is used repeatedly.

Therefore, the present invention has high sensitivity to long wavelength light,
Moreover, in order to obtain a long-life composite electrophotographic photoreceptor in which electrophotographic properties such as resolution do not deteriorate due to repeated portions, the blending ratio of the oxazole compound and resin in the charge transport layer should be adjusted as described above. The important point is to set it within a reasonable range.

In addition, the blending ratio of the above compound in the charge transport layer is 115
If the amount is below, the photosensitivity of the photoreceptor will drop sharply and it will become unusable, so the blending ratio cannot be drastically reduced.

Next, a method for forming the charge generation layer and the charge transport layer on the conductive support will be described. First, the charge generation layer is prepared by thoroughly dispersing the metal-free phthalo-7-anine and mixing it well with an organic solution that dissolves the component well, such as tetrahydrofuran, ethyl acetate, acetone, methyl ethyl ketone, etc.
The conductive support is immersed in this solution, or this solution is dropped onto the conductive support and coated using a bar coater, roll coater, applicator, casting method, etc., and the organic solvent is removed by heating and drying. On the other hand, the charge transport layer is made by adding the compound and resin weighed in a predetermined ratio to tetrahydrofuran, methylene chloride, dichloroethane, trichloroene, etc.
Tetrachloroethane.

Dissolve it in a chlorinated organic solvent such as chlorobenzene,
Using this solution, a charge transport layer is further formed on the conductive support on which the charge generation layer has been formed by the same method as above.

When producing a composite electrophotographic photoreceptor using the above method,
The thickness of one layer of charge generation varies depending on the particle size of the metal-free phthalocyanine used, but basically the phthalo-7anine particles are arranged in a single layer and most densely (0.1 to 3 μm).
) is desirable. If the charge generation layer is extremely thin, the photosensitivity of the photoreceptor will be extremely low, while if it is too thick, the charging characteristics will deteriorate. On the other hand, the thickness of the charge i general transport layer is preferably in the range of 10 to 30 μm. When the charge transport layer has an i' oh value, there is a problem in the stability of the photoreceptor (bistability of various electrophotographic properties upon repeated use), and on the other hand, when the thickness exceeds 30 μm, the photosensitivity decreases.

In addition, the photoreceptor formed by the above method may be used in combination with a known charge-generating substance or charge-transporting substance, and the film-forming properties of the coating liquid may be adjusted to the extent that the object of the present invention is not impaired.

Various additives can be added to improve adhesion, abrasion resistance, etc.

[Embodiments of the invention]

Reference Example 1 α-type metal-free phthalocyanine (Monolite Fast Pull GS manufactured by ICI) was extracted and purified 93 times with heated dimethyl formaldehyde. By this operation, the crystal form becomes β
It transferred to the mold. Next, 1 of this β-type metal-free phthalocyanine
A portion was dissolved in concentrated sulfuric acid, and this solution was poured into ice water to cause reprecipitation, thereby converting it to the α form. This reprecipitate was washed with aqueous ammonia, methanol, etc., and then dried at 70C. Next, the α-type metal-free phthalonanine purified above was placed in a sand mill together with a grinding aid and a dispersant, and kneaded at a temperature of 100±200 for 15 to 25 hours. After confirming that the crystal form has changed to the τ type by this operation, it is taken out from the container, the grinding aid 2 dispersion medium is sufficiently removed with water and methanol, etc., and it is dried to give a clear greenish τ. Blue crystals of type-free metal phthalo-7-anine were obtained. α, β obtained in this way
Table 1 shows the infrared absorption spectra of the and τ-type gold metal and ringphthalocyanine. In the table, the units of numbers are low 1, absorption strength is weak...W, intermediate...m5, strong...S, and Sh indicates shoulder. As is clear from Table 1, the absorption wave number of the τ type metal-free phthalocyanine at 700 to 800 cm-'' is different from that of the α and β types.

Table 1 Example 1 1 part by weight of the τ-type metal-free phthalocyanine (average particle size: φ0.3×1 μm) obtained in the above reference example, 0.005 parts of methylphenylsiloxane compound KP-323 (manufactured by Shin-Etsu Chemical Co., Ltd.)
Parts by weight and 30 parts by weight of methylene chloride were kneaded in a ball mill for about 5 hours to prepare a coating liquid for a charge generation layer. This coating liquid was applied onto Atsube foil having a thickness of 100 μm using an automatic applicator (manufactured by Toyo Seiki Co., Ltd.), and dried at 80 C for 30 minutes to form a charge generation layer. The thickness of this layer is 0.5 μm. Next, 1 part by weight of an oxazole compound having the following structural formula is used as a charge transport substance in the present invention, and this is mixed with 4 parts by weight of a polycarbonate resin (Lexan 141-111 manufactured by GE) and a methylphenylsiloxane compound K P =323 0 .004
A coating liquid for a charge transport layer was prepared by dissolving each part by weight in a mixed solution of 10 parts by weight of methylene chloride and 15 parts by weight of 1,2-dichloroethane. This coating tL was applied on the charge generation layer using an automatic applicator, and the temperature was 30°C at 90C.
The charge transport layer was formed by drying for a minute. The thickness of this layer is 1
It is 5 μm.

Ratio Examples 1 and 2 A charge generation layer and a charge transport layer were formed on aluminum foil in exactly the same manner as in Example 1 except that the α and β type metal-free phthalonanine obtained in the above reference example were used.

Next, the electrophotographic characteristics of the composite electrophotographic photoreceptors prepared in Embroidery Example 1 and Comparative Examples 1 and 2 were measured. For measurement, electrostatic recording paper tester 5P-428 (manufactured by Kawaguchi Electric)
Using the dynamic mode, charge the corona charger for 10 seconds with the power supply voltage set to -5 kV, leave it in the dark for 30 seconds, and then irradiate it with 107 ux (measured value when stationary) using a tungsten lamp. During this time, the surface potential of the photoreceptor was recorded with a recorder, and the potential after charging was Vo minus the potential after being left for 30 seconds, V3G, and the half-decreased exposure amount F: 5o (V3o was V30/
The amount of exposure required to reach 2 (unit: zux = S) was read. Furthermore, in a similar measurement system, the light source...
Using a Rogen lamp (600W), the problem of 800±
The half-decrease exposure amount ES:0 for light with a wavelength of 1 nm was also measured, and the sensitivity was determined to be 1/E5o. When 800 nm monochromatic light is used as a light source, the illuminance is about 20 nW/m2. The results are shown in Table 2. As is clear from Table 2, the photoreceptor using τ-type phthalocyanine of Example 1 has a particularly long wavelength of 8Q Q II m compared to the photoreceptor using α- and β-type phthalocyanine of Comparative Examples 1 and 2. It has excellent sensitivity to light.

Example 2 1 part by weight of fresh phthalocyanine obtained in Reference Example 1, 6 parts by weight of modified silicone tree I 1% KR-5240 (manufactured by Shin-Etsu Chemical Co., Ltd., solid content 15% by weight), methylphenylsiloxane compound KP-3230,005 Parts by weight and 40 parts by weight of tetrahydrofuran were kneaded in a ball mill for about 5 hours to prepare a coating liquid for a charge generation layer. This coating liquid was applied onto a 100 μm thick aluminum foil using an automatic applicator and dried at 80 C for 30 minutes to form a charge generation layer 0.5 μm thick.

Next, 1 part by weight of an oxazole compound having the following structural formula was used as a charge generating substance, and this was mixed into a modified polycarbonate resin (Makloson KL-1-1142, manufactured by Bayer AG).
is dissolved in 20 to 30 parts by weight of 1,2-dichloroethane along with 1 to 6 parts by weight and methylphenylsiloxane compound KP-3230,005 parts by weight, so that the blending ratio of the oxazole compound and modified polycarbonate resin is 1/1.1.
/2.1'/3.1/4.115° 1/6 of six types of coating liquids for the charge transport layer were prepared. This coating solution was applied onto the charge generation layer prepared above and dried at 90C for 30 minutes to form a charge transport layer having a thickness of about 15 μm, thereby obtaining six types of composite type electrophotographic photoreceptors. The photographic characteristics of these photoconductors were measured in the same manner as described above, and each photoconductor was irradiated with a DC corona of -5 kV, and then a resolution evaluation pattern of AI R was closely exposed to electrostatic A latent image was formed.

Next, a positive donor was attached to this latent image, and a toner powder image was developed on the photoreceptor. A transfer paper was placed over the generated powder image, and a direct current corona of minus 5 kV was irradiated from the back side to perform transfer, and the resolution was evaluated after heat fixation. The results are shown in Table 3. Third
As can be seen from the table, when the proportion of the charge transport agent in the charge transport layer is high, the sensitivity is good, but the charging potential and resolution are low. Conversely, if the amount is too small, the charged potential and resolution will be high, but the sensitivity will be poor. In order to balance the charge transporting agent and resin properties, the blending ratio of charge transport agent and resin should be 1.
It is clear that the range of /2 to 115 is good.

Next, 50,000 copies were made on these photoreceptors using a copying machine, and the electrophotographic characteristics and resolution were evaluated after repeated corona irradiation and exposure corresponding to water. The results are shown in Table 3 as characteristics after the test.

As is clear from these results, the photoreceptor exhibits excellent durability without any change in characteristics or deterioration in resolution.

〔Effect of the invention〕

As described above, the composite type Seiko photographic photoreceptor of the present invention has high sensitivity not only to visible light but also to long wavelength light, and is also excellent in durability, making it particularly suitable as a photoreceptor for semiconductor laser beam printers. .

Continued from page 1 0 Inventor Manabu Sawada Toyo Ink Mfg. Co., Ltd. 2-3-13 Kyobashi, Chuo-ku, Tokyo Applicant Toyo Ink Mfg. Co., Ltd. 2-3-13 Kyobashi, Chuo-ku, Tokyo

Claims (1)

[Scope of Claims] 1. A composite electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer formed on a conductive support, in which the charge generation layer contains a τ type or τ' type charge generation material. , η-type and/or η′-type gold metal phthalocyanine, and the charge transport layer is a divalent group selected from the general formula alkylidene group, arylene group, and cycloalkylidene group). A composite electrophotographic photoreceptor characterized by comprising and. 2. The composite electrophotographic photoreceptor according to claim 1, wherein the charge transport layer uses a mixture of the charge transport substance of the formula below and the resin in a weight ratio of 1/2 to 115. . 4 [wherein Y is at least one heterocyclic group selected from the group consisting of and (
However, Z represents 0 or S, the heterocyclic group may be substituted), n represents o, 1 or 2, and
and R4 is an alkyl group having 3 or less carbon atoms. 3. The charge generation layer has a thickness of 0.1 to 3 μm, and the charge transport layer has a thickness of 10 to 30 μm. Composite electrophotographic photoreceptor.